Thermoplastic fuel tank having reduced fuel vapor emissions

ES 2 201 270 T3

DESCRIPTION

Thermoplastic fuel tank with reduced fuel vapor emissions.

The invention relates to an improved fuel tank, container or tank for a motor vehicle that contains a barrier to the passage of fuel vapor by permeation or diffusion from the interior of the container to the environment. The fuel vapor may comprise a vapor derived from an aromatic, aliphatic, olefinic liquid hydrocarbon, etc., fuel oxygenates, alcohol, etc. The motor vehicle fuel container can be made, in whole or in part, of thermoplastic materials such as polyethylene, polypropylene, polyester, and other useful thermoplastic materials. Such single-layer or component materials can be made or they can be made of laminated or laminated materials comprising a thermoplastic material, a metal component, and synthetic fibers, heat-set materials, etc. The fuel tanks of the invention incorporate a barrier component or barrier structure to reduce the tendency of fuel vapor to penetrate through the fuel container to the atmosphere. The thermoplastic fuel tank can be manufactured using a variety of known techniques.

Background of the invention

Motor vehicle fuel tanks have been in use for many years. Primarily, the typical fuel tank currently in use is substantially box-like, cylindrical or rectangular in shape and may contain from about 40 to 100 liters or more of a liquid fuel. Fuels can include diesel, gasoline, gasohol, etc. Typically, a fuel tank can be made by welding typically metallic half-shell portions to form a sealed tank system. Other metal forming and sealing systems are known. A filler neck or loading tube is often installed in the tank with a variety of sealing mechanisms. Such a fuel filler tube may also be closed with valve or vapor tight shutoff mechanisms to prevent the escape of fuel vapor during refueling and use. Current fuel tanks installed in motor vehicles are typically metallic in nature and are typically quite impervious to the passage of fuel vapor. Typically, vapor can be lost through gaskets between metal sections, an instrument sensor port, the fuel line that carries fuel to the engine, or the filler neck during vehicle refueling. Examples of fuel containment systems used during refueling are shown in US Patent No. 4,131,141 to Weissenbach, US Patent No. 4,977,936 to Thompson et al., And US Patent No. 4,598,741 to Johnson. et al.

Recently, much attention has been paid to improvements in fuel tank design. A large number of patents have been directed to the manufacture of fuel tanks of thermoplastic, composite or heat-set materials with the use of a variety of laminated or composite structures. Such structures can include layers derived from thermoplastic materials, thermosetting materials, natural and synthetic fibers, metallic fibers, metallic layers, cover layers derived from compositions dissolved in water and in solvents, etc. A problem that arises from the use of such materials in a fuel container is linked to the increased permeability of fuel vapor through the organic polymeric materials in the container as compared to metallic deposits. A fuel tank comprising a significant proportion of a thermoplastic resin such as polyethylene or polypropylene as the main structural component can have substantial fuel permeability. Such deposits can release significant proportions of smoke or vapor, typically comprising an aromatic, an aliphatic, an oxygenate, an alcohol, etc. or mixtures of these. Other thermoplastic or thermosetting materials, depending on their chemical constituents, can also release a certain proportion of the aromatic compound content of fuels, oxygenated materials such as methyl tertiary butyl ether, ethanol, methanol, etc.

An example of a plastic fuel tank consisting of a layer of a thermoplastic resin is disclosed in JP 63033252A, where the resin contains 20% by weight or less of regular cyclodextrin to reduce fuel permeability.

For any fuel tank using the improved technologies to be successful, it must have improved barrier properties to the passage of fuel vapor through the tank. One technique used to improve the barrier properties of fuel tanks involves the formation of a multilayer structure that includes one or more layers endowed with improved barrier properties. US Patent No. 3,616,189 to Harr teaches an improved container having multiple layers including a nylon barrier film. US Patent No. 5,102,699 to Beeson et al. Teaches a layered film that uses polyvinyl alcohol as a solvent barrier layer. US Patent No. 5,230,935 to Delimony et al. teaches a multilayer material that uses a variety of compositions to improve the barrier properties of the material. US Patent No. 5,398,729 to Spurgat teaches a fuel hose whose barrier properties are derived from layers of impermeable tape, metallic layers that helically wrap a tubular extrudate of rubber. These structures have achieved some degree of success in improving barrier properties. However, the manufacture of multilayer or laminated materials often involves complex and expensive process steps and expensive materials.

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Specific additive chemical barrier materials have been incorporated into fuel tank structures to improve barrier properties. US Patent No. 3,740,258 to Walles and US Patent No. 4,371,574 to Shefford teach that the addition of sulfonic acid or sulfonate groups to the surface of tank materials can improve barrier properties. These groups are formed by sulfonation of the polymer surface with gaseous sulfonating reagents. US Patent No. 4,719,135 to Gerdes et al. teaches the improvement of the barrier properties of fuel deposits through the use of a varnish layer comprising an epoxy resin, an amine, a curing agent, and a flexibilizer or plasticizer material. US Patent No. 4,938,998 to Stock teaches that a cellulosic derivative functionalized by phosphate, sulfate, carbonate or amino as a surface coating, in a polypropylene or polyethylene tank, can improve the barrier properties to the passage of fuel vapor. . US Patent No. 4,965,104 to Barton et al. teaches that closed thermoplastic containers based on carbon monoxide or sulfur dioxide copolymers can exhibit improved barrier properties. US Patent No. 5,006,377 to Delcorps et al. teaches that improved barrier membranes containing a chlorine-containing polymer and an adhesive layer consisting of a copolyamide exhibiting a specific degree of crystallization, in combination with a fluorine-containing polymer can form improved barrier layers. US Patent No. 5,244,615 to Hobbs teaches that improved barrier properties to the passage of hydrocarbon fuel vapor can be improved with the use of a fluoropolymer. In the Hobbs document, during blow molding of a fuel container, a measured amount of gaseous fluorine is introduced into the blown gas. During molding operations, gaseous fluorine reacts with the polymer composition at the elevated molding temperature to effectively fluorinate the surface, resulting in an improved barrier layer. US Patent No. 5,314,733 to Saito et al. teaches a multi-layer fuel container structure. The multilayer composite comprises a first structural layer, an adhesive layer, and a third structural layer.

While many of these systems that involve the use of chemical agents to improve barrier properties have utility in barrier systems, many of these systems involve corrosive chemical systems, complex laminated structures, and other aspects that would require a significant investment in the development of efficient manufacturing methods. A significant need for improvement in fuel vapor barrier systems is present in this fuel tank technology.

Brief description of the invention

The invention resides in an improved fuel tank that exhibits substantial barrier properties to the passage of fuel vapor from the interior of the tank, through the tank structure, to the environment. The fuel vapor barrier properties of the fuel tank arise from at least one layer comprising a thermoplastic material having a barrier additive cyclodextrin material substantially free of an inclusion compound dispersed in the thermoplastic material.

According to a first aspect of the present invention there is provided a fuel container exhibiting improved fuel vapor barrier properties, the reservoir comprising:

(a) a rigid shell comprising a thermoplastic polymer; and (b) having an effective fuel vapor absorbent amount of a cyclodextrin material uniformly dispersed throughout the polymeric shell;

characterized in that the cyclodextrin is free of a complex inclusion compound and cooperates with the thermoplastic polymer to provide fuel vapor barrier properties, where the cyclodextrin comprises an α-cyclodextrin, a / 1-cyclodexlrin, a γ-cyclodextrin or mixtures of these, having pendant portions or substituents of an acetyl or trimethylsilyl derivative that make the cyclodextrin compatible with the thermoplastic polymer.

The cyclodextrin material can be made more compatible with the thermoplastic by introducing at least one substituent on a primary or secondary hydroxyl (-OH) of the cyclodextrin. A substituent is selected to improve the compatibility between the modified cyclodextrin and the thermoplastic material. An effective amount of the modified cyclodextrin is introduced into the thermoplastic such that fuel molecules passing through the thermoplastic layer are trapped in the inner pore of the cyclodextrin material and are complexed and retained as a host molecule by the cyclodextrin. The compatible cyclodextrin or modified cyclodextrin material is a compound substantially free of an inclusion complex. For the purposes of this invention, the term "substantially free of an inclusion complex" means that the amount of cyclodextrin dispersed in the fuel tank structure contains a large effective barrier fragment of cyclodextrin having free rings of one molecule. permeant to the fuel within the cyclodextrin molecule or other inclusion complex molecule. A certain proportion of the cyclodextrin is inherently filled with a host molecule. The cyclodextrin can be added to the thermoplastic material without the complexed material. However, some degree of complexation of cyclodextrin can occur during manufacture due to degradation of the polymer or of the inks, coating components, or other materials used in conjunction with the thermoplastic material. The barrier properties arise from having a substantial fraction (greater than 50 mole% to 100 mole%) of the cyclodextrin molecules with an interior cavity vacated by any fuel permeant or other component.

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The fuel tank of the invention can be a single layer or structural shell of a thermoplastic material having a barrier additive cyclodextrin material uniformly distributed in the thermoplastic. Additionally, the tank may be a laminated or multilayer fuel tank comprising a structural layer and a barrier layer. The cyclodextrin may be in the structural layer, in any or all of the laminated layers, or in a single layer or intermediate film layer in a multilayer structure.

According to another aspect of the present invention there is provided a fuel tank for use in a motor vehicle, provided with improved fuel vapor barrier properties, the tank comprising a shell having at least two layers:

(a) a first layer comprising a structural thermoplastic material; and (b) a second layer comprising a thermoplastic film or cover layer comprising a continuous thermoplastic web having dispersed in the web, a fuel vapor effective barrier amount of a modified cyclodextrin having pendant or substituent portions of a derivative. acetyl or trimethylsilyl that make the cyclodextrin compatible with the thermoplastic polymer;

characterized in that the cyclodextrin is free of a complex inclusion compound and cooperates with the thermoplastic band to provide barrier properties.

Additionally, the fuel tank can be prepared by joining tank half sections at a joint edge and sealing the tank using heat welding, hot melt adhesives, hot-setting adhesives (e.g., epoxy or urethane), flange clamps, or other sealing technology. known sealed. In such a reservoir, the barrier material may be an additive in the structural polymer, an exterior coating, an interior bladder or balloon layer, an interior liner, or a blow-molded interior layer.

The tanks can be manufactured with a port for a fuel pump or fuel line, a port for instrument installation, port for charge tube and mounting tabs or other mounting means. The tanks can be made in virtually any shape or configuration and can have a surface relief that provides added strength to the structure of the tank. Finally, the tank can hold virtually any volume of liquid fuel from 500 milliliters to 250 liters or more depending on the size of the vehicle and the engine. Preferably, fuel tanks for passenger cars can range from about 30 liters to 100 liters or more. Fuel tanks for larger vehicles such as trucks, delivery vehicles, buses, electric locomotives, etc. they can range from 120 liters to 300 liters or more. In aviation, fuel tanks can hold from approximately 100 to 20,000 kg or more of fuel.

Brief discussion of the drawings

Figure 1 is a graphical representation of the dimensions of the cyclodextrin molecule without derivatization. An α-, β- and γ-cyclodextrin are shown.

Detailed description of the invention

The cyclodextrin barrier material can be introduced into the bulk polymer used for the fabrication of the fuel tank or it can be incorporated into a barrier film or layer used in the production of a laminated or multilayer tank.

Wall or barrier film

The thermoplastic material and cyclodextrin can be configured in the form of the fuel tank wall, an inner or outer liner, or an inner balloon or bladder. A wall, film, or sheet is a flat, unsupported section of a thermoplastic resin whose thickness is much less than its width or length. Films are generally considered to have a thickness of 0.25 millimeter (mm) or less, typically 0.01 to 20 mm. The thickness of the sheet can range from about 0.25mm to several centimeters (cm), typically 0.3 to 3mm. The film or sheet can be used alone or in combination with other sheet, fabric or structural units by lamination, coextrusion or coating. The wall thicknesses of the fuel tanks range from approximately 2 mm to 3 cm. For the invention the term "web" includes semi-rigid and rigid film, sheet, sheet or wall and shaped rigid units. Important properties include tensile strength, elongation, stiffness, strength, and tear resistance; optical properties including haze, transparency; chemical resistance such as water absorption and transmission of a variety of permeable materials including water vapor and other permeants; electrical properties such as dielectric constant; and durability properties including shrinkage, cracking, weatherability, etc. In this application the term "barrier layer" includes a film, sheet, wall, liner, bladder or balloon.

Thermoplastic materials can be formed into barrier layer film using a variety of processes including thermoplastic blown extrusion, solvent casting, thermoforming, blow molding, injection molding, extrusion of linear biaxially oriented films, and casting from resin.

ES 2 201 270 T3 a molten thermoplastic, monomer or polymer dispersions (in water or organic solvent). These methods are well known manufacturing procedures. The characteristics of thermoplastic polymers that lead to the successful formation of barrier films are as follows. Thermoplastic polymer manufacturing experts have learned to tailor polymeric material for thermoplastic processing and end-use application determined by controlling molecular weight (melt index has been selected by the thermoplastic industry as a measure of molecular weight, the melt index is inversely proportional to molecular weight, density and crystallinity). Thermoplastic extrusion blown polyolefins (low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE)) are the most frequently used thermoplastic polymers, although polypropylene, nylon, nitriles , poly (ethylene-co-terephthalate) PETG and polycarbonate are sometimes used to make blown film. Polyolefins typically have a melt index of 0.2 to 3 grams / 10 min., A density of about 0.910 to about 0.940 grams / cm³ , and a molecular weight (mw) that can range from about 200,000 to 500,000. For the extrusion of biaxially oriented film, the most frequently used polymers are based on olefins - mainly polyethylene and polypropylene (the melt index of approximately 0.1 to 4, preferably 0.4 to 4 grams / 10 min. , and a molecular weight (mw) of about 200,000 to 600,000). Polyesters and nylons can also be used. For casting, molten thermoplastic resin or monomer dispersions are typically produced from polyethylene or polypropylene. From time to time, nylon, polyester, and PVC are sneaked in. For roll-applied coatings of aqueous acrylic, urethane and PVDC dispersions etc., they are polymerized to optimum crystallinity and molecular weight prior to coating. A variety of thermoplastic materials are used to make film and sheet products. Such materials include poly (acrylonitrile-co-butadiene-co-styrene) polymers, acrylic polymers such as polymethylmethacrylate, poly-n-butyl acrylate, poly (ethylene-co-acrylic acid), poly (ethylene-co-methacrylate). ), etc.; cellophane, cellulosics including cellulosic acetate, cellulosic acetate propionate, cellulosic acetate butyrate, and cellulosic triacetate, etc .; fluoropolymers including polytetrafluoroethylene (Teflon), poly (ethylene-co-tetrafluoroethylene) copolymers, (tetrafluoroethylene-co-propylene) copolymers, polyvinylfluoride polymers, etc., polyamides such as nylon 6, nylon 6,6, etc .; polycarbonates; polyesters such as poly (ethylene co-terephthalate), poly (ethylene co-1,4-naphthalene dicarboxylate), poly (butylene co-terephthalate); polyimidic materials; polyethylene materials including low-density polyethylene; linear low-density polyethylene, high-density polyethylene, high-molecular-weight high-density polyethylene, etc .; polypropylene, biaxially oriented polypropylene; polystyrene, biaxially oriented polystyrene; vinyl films including polyvinyl chloride, copolymers of (vinyl chloride-co-vinyl acetate), polyvinylidene chloride, polyvinyl alcohol, copolymers of (vinyl chloride-co-vinylidene dichloride), films special including polysulfone, polyphenylene sulfide, polyphenylene oxide, liquid crystal polyesters, polyether ketones, polyvinylbutyryl, etc.

Film and sheet materials are commonly manufactured using thermoplastic techniques including melt extrusion, calendering, solution casting, and chemical regeneration processes. In many manufacturing steps an axial or biaxial orientation step is employed. Most films and sheets are manufactured using melt extrusion techniques. In melt extrusion, the material is heated above its melting point in an extruder that typically has an introductory heating section, a melt zone, and an extrusion section. The melt is presented to a slit row that produces a thin flat profile that is rapidly cooled to a solid state and oriented. Typically the hot polymeric film after extrusion is rapidly cooled on a roller or drum or using an air jet. Finally, a cooling bath can be used. Thermoplastic materials can be blown too. The hot melt polymer is extruded in an annular die in a tubular form: The initial form is inflated with air to a diameter determined by the desired properties of the film and by practical maintenance considerations. As the hot melt polymer exits the annular spinneret, the extruded hot tube air blows up to 1.2 or four (4) times the initial spinneret diameter. At the same time the cooling air cools the web forming an extruded element with a hollow circular cross section. The tube of film is collapsed into a V-shaped frame and clamped at the end of the frame to trap air within the bubble thus formed. The rollers pull the film off the die while maintaining a continuous production of the extruded tube.

We have found that in the preparation of a biaxially oriented film and in the production of blown thermoplastic film that the melt temperature and the die temperature are important in obtaining the preferred permeability or permeant transmission rates for the films of the invention, to reduce melt fracture and improve film uniformity (reduce surface defects). The temperature of the melt in the melting zone should range from about 390-420 ° F (198.89-215.56 ° C), preferably 395415 ° F (201.67-212.78 ° C). The extrusion die temperature should be approximately 400-435 ° F (204.44223.89 ° C), preferably 410-430 ° F (210-221.11 ° C). The extruded polymer can be cooled using room temperature water baths or room air. The extruder can be operated at a production speed such that production rates can be maintained but that the polymer can be heated sufficiently to achieve the required melt and die temperatures. Producing the films of the invention at these temperatures ensures that the cyclodextrin material is fully compatible in the thermoplastic melt, is not degraded by high temperatures, and a transparent compatible useful barrier film is produced.

Two thermoplastic materials are often joined together in a coextrusion process to produce a custom made film, sheet or wall container type product adapted to a fuel tank. One or more types of polymer in two or more layers of melt are coextruded in a coextrusion die to obtain a film with versatile properties derived from both layers. Layers of different polymers or resins are combined

ES 2 201 270 T3 either by mixing the materials in the melt before extrusion or by parallel extrusion of the different thermoplastic materials. The melt flows in a laminar fashion through the die and into a cooled drum. The film is processed in a conventional way and can be oriented after cooling. The films can contain a variety of additives such as antioxidants, heat stabilizers, UV stabilizers, slip agents, fillers, and anti-seize agents without negative effects on barrier properties.

The barrier layer of the invention can also be made by casting an aqueous dispersion or organic solvent dispersion or solution of a film-forming polymer and the cyclodextrin derivative. The material dissolved in water or solvent can be formed by the current available processing of aqueous or solvent solutions of polymers, dispersions of polymers, solutions of commercially available polymers, or the technology of processing both polymers and of ordinary water or solvent processes. The derived cyclodextrin material can be combined with such aqueous or solvent dispersions or solutions to form an easily formed film-forming or coating material. Such barrier layers or barrier coatings can be formed using commonly available coating technology, including roll coating, doctor blade coating, spin coating, etc. Although coatings can be made on and removed from a preparative surface, the coatings are typically formed on a thermoplastic or heat-set polymer web and remain in place to act as a barrier layer on a polymer web used in the field. packing. Typical coatings can be made of the same thermoplastic polymeric materials used in film sheets or other structural layers using substantially similar fillers of the derived cyclodextrin material. The barrier layer or barrier coatings formed using the film-forming polymer and the cyclodextrin derivative can be used as a single coating layer or can be used in a multi-coating structure having a barrier layer or coating on one or both sides of a structural film or sheet that can be used with other overlay layers including print layers, clear coating layers and other layers conventionally used in packaging, packaging of food products, consumer products, etc.

Cyclodextrin materials can be incorporated into a cellulosic barrier web by coating the cellulosic web or similar structure containing a cellulosic layer with a liquid coating composition containing an effective amount of a cyclodextrin or substituted cyclodextrin. Such coating compositions are typically formed using a liquid medium. Liquid media can include aqueous media or organic solvent media. Aqueous media are typically formed by combining water with additives and components that can form a useful applicable aqueous dispersion. Solvent dispersions based on organic solvents can be made using the corresponding known basic solution coating technology.

In forming the barrier layers of the invention, the coatings can be formed either on a film which is then laminated with a film which is subsequently laminated on the cellulosic web or can be applied to form a film on the cellulosic web. Such coating processes involve the application of a liquid to a moving cellulosic web. Such coating processes commonly use machines having an application section and a metering section. Careful control of the amount and thickness of the coating results in optimized barrier layers without wasted material. Various coating machines are known such as tension sensitive coaters, for example coaters using a measuring stick, tension insensitive coating stations that can maintain the weight of the layer even as web tensions vary, the methods brush coating machines, air knife coaters, etc. Such coating machines can be used to cover one or both sides of a flexible film or one or both sides of a cellulosic web.

The above-described coating machines commonly apply a liquid composition containing a film-forming material, additives that can help form and maintain the coating composition along with the effective amount of the cyclodextrin material or substituted cyclodextrin material. Film-forming materials are often called binder. Such binders exist in the final layer as a high molecular weight polymer. Both thermoplastic polymers and crosslinking polymers can be used. Such binders are grouped into certain overlapping classes including acrylic, vinyl, alkyl, polyester, etc. Additionally, the compositions described above which are materials that can be used in the formation of the polymeric films, also have corresponding materials that can be used in the formation of coating compositions in aqueous solutions and in solvents. Such coating compositions can be made by combining the liquid medium with solid materials containing the polymer, cyclodextrin, and a variety of useful additives. Typically, cyclodextrin materials are added to the coating composition as part of the solid component. The solids present in the coating composition may contain from about 0.01 to about 10% by weight of the cyclodextrin compound, preferably from about 0.1% by weight to 5% by weight, more preferably from about 0%. , 1% by weight to about 2% by weight of the cyclodextrinic material based on the total solids in the solvent dispersion composition.

Structural bands including a barrier layer

The fuel tank of the invention may take the form of a single layer or single component structural member made from a thermoplastic material having the cyclodextrin barrier material uniformly dispersed throughout the single component structure. Typical structural shapes and materials can be used in the fabrication of such a reservoir. Virtually all of the above-described film materials can be formed into structural members in a non-flexible structural reservoir component.

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Such deposits can be made by forming or casting a single unit or they can be made by joining two or more sections into a finished unit. Such bonding can be achieved by employing heat or thermal welding, adhesives (both thermoplastic and heat-set), mechanical clamps or otherwise, etc. Additionally, tanks may be formed having ports for the installation of sensors and for the fuel inlet pipes. The barrier properties of such a reservoir can be enhanced by using an outer coating formed on the reservoir by employing the technology of the invention or by inserting a flexible bag-like bladder or container into the interior of the reservoir.

Cyclodextrin

The thermoplastic containers of the invention contain a cyclodextrin or a modified cyclodextrin material that have pendant portions or substituents that make the cyclodextrin material compatible with the thermoplastic polymer. For this invention, the term "compatible" means that the cyclodextrinic material can be uniformly dispersed in the polymer in the melt, can retain the ability to trap or complex the permeable materials or impurity of the polymer, and can reside in the polymer without substantially reducing the characteristics of the polymer. Compatibility can be determined by measuring polymer characteristics such as tensile strength, tear resistance, etc., permeability or transmission rates for permeants, surface smoothness, transparency, etc. Incompatible derivatives will produce substantially reduced polymer properties, very high permeability or transmission rates, and a poorly transparent rough film. A qualitative classification of compatibility can be obtained by preparing a few small batches (100 grams to one kilogram of thermoplastic material and substituted cyclodextrin). The mixed material is extruded at production temperatures as an extruded linear strand having a diameter of approximately one to five mm. Incompatible cyclodextrin materials will not be uniformly dispersed in the melt and can be seen immediately in the transparent melt polymer as it is extruded from the extrusion head. We have found that incompatible cyclodextrin can degrade at extrusion temperatures and can produce a characteristic "burnt flour" odor in an extrusion. Additionally, we have found that incompatible cyclodextrin can cause substantial melt fracture in the extrudate which can be detected by visual inspection. Finally, the extrudate can be cut into small pieces, sectioned, and examined using an optical microscope to find the incompatible cyclodextrin clearly visible in the thermoplastic matrix. Cyclodextrin is a cyclic oligosaccharide consisting of at least six glucopyranose units linked by α (1 ^ 4) bonds. Although cyclodextrins of up to twelve glucose residues are known, the three most common homologues (α-cyclodextrin, / t-cyclodexlrin and γ-cyclodextrin) having 6, 7 and 8 residues have been used.

Cyclodextrin is produced by highly selective enzymatic synthesis. They consist of six, seven, or eight glucose monomers arranged in a donut-shaped ring denoted α-, β-, or γ-cyclodextrin respectively (see Figure 1). Specific coupling of glucose monomers gives cyclodextrin a rigid frustoconical molecular structure with a hollow interior of a specific volume. This internal cavity, which is lipophilic (that is) attracts hydrocarbon materials (in aqueous systems it is hydrophobic) compared to the exterior, is an important structural feature of cyclodextrin, providing the ability to complex molecules (eg aromatics , alcohols, hydrogen halides and halides, carboxylic acids and their esters, etc.). The complexed molecule must meet the size criteria of at least partially fitting into the inner cavity of the cyclodextrin, resulting in an inclusion complex.

Typical properties of cyclodextrin

<td>Properties</td><td>CD α-CD</td><td>£ -CD</td><td>γ-CD</td>

<td>Degree of polymerization (n =)</td><td> 6</td><td> 7</td><td> 8</td>

<td colspan="4">Molecular size (¿A)</td>

<td>inside diameter</td><td> 5,7</td><td> 7,8</td><td> 9,5</td>

<td>external diameter</td><td> 13,7</td><td> 15,3</td><td> 16,9</td>

<td>height</td><td> 7,0</td><td> 7,0</td><td> 7,0</td>

<td>Specific rotation [a]²⁵D</td><td> +150,5</td><td> +162,5</td><td> +177,4</td>

<td>Color of the iodine complex</td><td>Blue</td><td>Yellow</td><td>Brown yellowish</td>

Solubility in water (g / 100 ml) 25 ° C

Distilled water 14.50 1.85 23.20

The oligosaccharide ring forms a torus, frustoconical in configuration, with the primary hydroxyl groups of each glucose moiety located at a narrow end of the torus. Secondary glucopyranosic hydroxyl groups are at the broad end. The parent cyclodextrin molecule, and useful derivatives, can be represented by

ES 2 201 270 T3 following formula (ring carbons show conventional numbering) in which free bonds represent the rest of the cyclic molecule:

<img file="ES2201270T3_D0001.tif" />

where R1 and R2 are the primary or secondary hydroxyls as shown.

Cyclodextrin molecules have available for reaction with a chemical reagent the primary hydroxyl at position six, of the glucose moiety, and at the secondary hydroxyl at positions two and three. Due to the geometry of the cyclodextrin molecule, and the chemistry of the ring substituents, all hydroxyl groups are not equal in reactivity. However, with care and efficient reaction conditions, the cyclodextrin molecule can be reacted to obtain a derivatized molecule having all hydroxyl groups derivatized with a single type of substituent. One such derivative is a persubstituted cyclodextrin. Cyclodextrin with selected substituents (ie) substituted only on the primary hydroxyl or selectively substituted only on one or both of the secondary hydroxyl groups can also be synthesized if desired. A further directed synthesis of a molecule derivatized with two different substituents or three different substituents is also possible. These substituents can be randomly placed or they can be targeted to a specific hydroxyl. For the purposes of this invention, the cyclodextrin molecule must contain sufficient substituent groups compatible with the thermoplastic in the molecule to ensure that the cyclodextrin material can be uniformly dispersed in the thermoplastic and when already formed into a transparent rigid film, sheet or structure. and does not impair the physical properties of the polymer.

Apart from the introduction of the substituent groups on the hydroxyl of the cyclodextrin, other modifications of the molecule can be used. Other carbohydrate molecules can be incorporated into the cyclic backbone of the cyclodextrin molecule. Primary hydroxyls can be replaced using SN2 displacement, oxidized dialdehyde, or acid groups can be formed for further reaction with the derivatizing groups, etc. Secondary hydroxyls can be reacted and can be removed leaving an unsaturated group to which a variety of known reagents can be added that can add or cross a double bond to form a derivatized molecule.

Additionally, one or more oxygens on the ring of the glycan moiety can open to produce a reactive center. These techniques and others can be used to introduce compatibilizing substituent groups into the cyclodextrin molecule.

The preferred preparatory scheme for producing a derivatized cyclodextrin material having a functional group compatible with the thermoplastic polymer involves one or more reactions at the primary or secondary hydroxyls of the cyclodextrin molecule. Generally speaking, we have found that a wide range of pendant substituent moieties can be used in the molecule. These derivatized cyclodextrin molecules may include acylated cyclodextrin, alkylated cyclodextrin, cyclodextrin esters such as the tosylates, mesylates, and other related sulfo derivatives, hydrocarbyl-amino-cyclodextrin, alkylphosphonocyclodextrin and alkylphosphatoci-clodextrin-substituted cyclodextrin, cyclodextrid-substituted cyclodextrin-functional cyclodextride groups, cyclodextrid-substituted cyclodextrin-functional groups. containing hydrocarbyl sulfur, Cyclodextrin substituted with silicon-containing functional groups, substituted cyclodextrin carbonate and carbonate, and carboxylic acid substituted cyclodextrin and related and others. The substituent portion must include a region that provides compatibility to the derivatized material.

Acyl groups that can be used as compatibilizing functional groups include acetyl, propionyl, butyryl, trifluoroacetyl, benzoyl, acryloyl, and other well-known groups. The formation of such groups on either the primary or secondary hydroxyls of the ring of the cyclodextrin molecule involves well known reactions. The acylation reaction can be conducted using the appropriate acid anhydride, the appropriate acid chloride, and well known synthesis protocols. A perazylated cyclodextrin can be prepared. Additionally, cyclodextrin having less than all available hydroxyls substituted with such groups can be made with one or more of the rest of the available hydroxyls substituted with other functional groups.

Cyclodextrin materials can also be reacted with alkylating agents to produce an alkylated cyclodextrin. Alkylating groups can be used to produce peralkylated cyclodextrin by employing sufficient reaction conditions to exhaustively react the available hydroxyl groups with the alkylating agent. Furthermore, depending on the alkylating agent, and the cyclodextrin molecule used under the reaction conditions, a cyclodextrin substituted in less than all available hydroxyls can be produced. Typical examples of alkyl groups useful to form the alkylated cyclodextrin include methyl, propyl, benzyl, isopropyl, tertiary butyl, allyl, trityl, alkylbenzyl, and other common alkyl groups. Such alkyl groups can be made using conventional preparative methods, such as reacting the hydroxyl group under appropriate conditions with an alkyl halide, or with an alkylating alkyl sulfate reagent.

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Tosyl (4-methylbenzenesulfonyl), mesyl (methanesulfonyl), or other related alkyl- or arylsulfonyl-forming reagents can be used in the manufacture of compatibilized cyclodextrin molecules for use in thermoplastic resins.

The primary -OH groups of cyclodextrin molecules react more easily than secondary groups. However, the molecule can be substituted in virtually any position to form useful compositions.

Such sulfonyl-containing functional groups can be used to derivatize any of the secondary hydroxyl groups or the primary hydroxyl group of any of the glucose moieties in the cyclodextrin molecule. Reactions can be conducted with the use of a sulfonyl chloride reagent that can react effectively with both the primary and secondary hydroxyl. Sulfonyl chloride is used with appropriate molar ratios depending on the number of target hydroxyl groups in the molecule that require substitution. Both symmetric (compounds persubstituted with a single sulfonyl moiety) and asymmetric compounds (the primary and secondary hydroxyls substituted with a mixture of groups including the sulfonyl derivatives) can be prepared using known reaction conditions. Sulfonyl groups can be combined with acyl or alkyl groups generically and selected to the taste of the experimenter. Lastly, a monosubstituted cyclodextrin can be made where a single glucose portion on the ring contains between one and three sulfonyl substituents. The remainder of the cyclodextrin molecule remains unreacted.

Amino derivatives and other azido derivatives of cyclodextrin having pendant portions containing the thermoplastic polymer can be used in the sheet, film or container of the invention. The sulfonyl derivatized cyclodextrin molecule can be used to generate the amino derivative from the sulfonyl group substituted cyclodextrin molecule by nucleophilic displacement of the sulfonate group by an azide ion (N3^-1). The azido derivatives are subsequently converted to substituted amino compounds by reduction. Large quantities of these azido or amino derivatives of cyclodextrin have been manufactured. Such derivatives can be made on symmetric substituted amine groups (those derivatives with two or more amino or azido groups arranged symmetrically on the cyclodextrin backbone) or as a derivatized cyclodextrin molecule symmetrically substituted with amine or azide. Due to the nucleophilic displacement reaction that produces the nitrogen-containing groups, the primary hydroxyl group at the 6-carbon atom is the most likely center for the introduction of a nitrogen-containing group. Examples of nitrogen containing groups that may be useful in the invention include acetylamino (-NHAc), alkylamino groups including methylamino, ethylamino, butylamino, isobutylamino, isopropylamino, hexylamino, and other alkylamino substituents. The amino or alkylamino substituents can also be reactive with other compounds that react with the nitrogen atom to produce more derivatives of the amine group. Other possible nitrogen containing substituents include dialkylamino such as dimethylamino, diethylamino, piperidino, piperizino, alkyl or aryl substituted quaternary ammonium chloride substituents, halogen derivatives of cyclodextrin can be made as a matrix mass for the manufacture of a cyclodextrin molecule substituted with a compatibilizing derivative. In such compounds the primary or secondary hydroxyl groups are substituted with a halogen group such as fluorine, chlorine, bromine, iodine or other substituents. The most likely position for the halogen substitution is the primary hydroxyl at the 6-position.

Hydrocarbyl substituted phosphono groups or hydrocarbyl substituted phosphate groups can be used to introduce compatible derivatives on the cyclodextrin. At the primary hydroxyl, the cyclodextrin molecule can be substituted with alkylphosphate or arylphosphate groups. The secondary hydroxyls at 2 and 3 can be branched using an alkyl phosphate group.

The cyclodextrin molecule can be substituted with heterocyclic nuclei including pendant imidazole groups, histidine, imidazole groups, pyridine and substituted pyridine groups.

Cyclodextrin derivatives can be modified with sulfur-containing functional groups to introduce compatibilizing substituents on the cyclodextrin. Aside from the acylating sulfonyl groups found above, sulfur containing groups made on the basis of sulfhydryl chemistry can be used to derivatize cyclodextrin. Such sulfur containing groups include methylthio (-SMe), propylthio (-SPr), t-butylthio (-SC (CH3) 3), hydroxyethylthio (-S-CH2CH20H), imidazolylmethylthio, phenylthio, substituted phenylthio, aminoalkylthio, and others. . Based on the ether or thioether chemistry discussed above, cyclodextrin can be prepared having substituents ending with a hydroxylaldehyde or carboxylic acid ketone functionality. Such groups include hydroxyethyl, 3-hydroxypropyl, methyloxylethyl and corresponding oxemo isomers, formylmethyl and its oxemo isomers, carbylmethoxy (-O-CH2-CO2H), carbylmethoxymethyl ester (-O-CH2CO2-CH3). Derivative cyclodextrin formed using silicone chemistry can contain compatibilizing functional groups.

Cyclodextrin derivatives with silicone-containing functional groups can be prepared. Silicone groups generally refer to groups with a single substituted silicon atom or a repeating silicone-oxygen backbone with substituent groups. Typically, a significant proportion of silicone atoms in the silicone substituent carry hydrocarbyl (alkyl or aryl) substituents. Silicone substituted materials typically have increased thermal and oxidative stability and chemical inertness. Additionally, the silicone groups increase weatherability, add dielectric strength, and improve surface tension. The molecular structure of the silicone group can be varied because the silicone group can have a single silicon atom or two to twenty silicon atoms in the silicone portion, it can be linear or branched, have a large number of groups

ES 2 201 270 T3 silicone-oxygen repetitive and can further be substituted with a variety of functional groups. Simple silicone-containing substituent moieties including trimethylsilyl, mixed methylphenylsilyl groups, etc. are preferred for the purposes of this invention. We are aware that certain / 1CD and acetylated and hydroxyalkyl derivatives are available from American Maize-Products Co., Corn Processing Division, Hammond, IN.

The above explanation of the nature of cyclodextrin derivatives, thermoplastic films, manufacturing details of bulk materials with respect to film production, and cyclodextrin processes for making derivatives compatible provides a basis for understanding the technology involved. in incorporating compatible cyclodextrin into thermoplastic structures for fuel vapor barrier purposes. The following examples, film preparation and permeation data provide an additional basis for understanding the invention and include the best mode.

After our work in the production of cyclodextrin and in the incorporation of cyclodextrins into thermoplastic films, we have found that it is easy to derivatize cyclodextrins using a variety of known chemical protocols. The cyclodextrin material can be melt blended into the thermoplastic materials smoothly resulting in transparent extrudable thermoplastic materials with the cyclodextrin materials evenly distributed throughout the thermoplastic. Additionally, we have found that cyclodextrin derivatives can be combined with a wide variety of thermoplastic films and structures. Cyclodextrin materials can be incorporated into films in a wide range of cyclodextrin concentrations. The thermoplastic materials containing the cyclodextrin can be blown to form films or can be formed into structures of varying thickness and can be made free from melt fracture or other variation of the film or sheet. We have found in our experimentation that the barrier properties, that is, the reduction of the vapor transmission rate of aromatic hydrocarbons, aliphatic hydrocarbons, ethanol and water can be achieved using derivatized cyclodextrin technology. In early work we have also found (1) that several modified cyclodextrin candidates are compatible with LLDPE resin and provide good complexation of residual volatile contaminants from LLDPE as well as reduction of organic permeants diffusing through the film. . (2) Selected derivatives of modified / 1CD (acetylated and trimethylsilyl ether) have no effect on transparency and thermal stability. The machinability of the extruded plastic material suffers some effect, causing some surface defects, thereby reducing the barrier properties of the film. (3) Films containing a modified / / CD composition (1% by weight) reduce aromatic pernetrants by 35% at 72 ° F (22.22 ° C) and by 38% at a temperature of 105 ° F (40.56 ° C); aliphatic pants are reduced by only 9% at 72 ° F (22.22 ° C). These results would be significantly improved if the worst shelf life test conditions were not used to test the films. (4) The complexation regimes were different between aromatic and aliphatic permeants. Films containing modified / 1CD have better complexation rates for aromatics (gasoline-type compounds) than for aliphatics (printing ink-type compounds). In contrast, film coating exhibits significantly better complexation for aliphatic compounds than for aromatic compounds. (5) ¿/ CD container acrylic coatings are the flagship products, reducing aliphatic pernents by 46% to 88%, while aromatics are reduced by 29%.

Qualitative preparation

Initially, we prepared four experimental test tube films as a template for the barrier layers. Three of the films contain / -cyclodextrin, / CD at loading levels of 1%, 3% and 5% (by weight) while the fourth is a control film made from the same batch of resin and additives but without the / CD. The 5% / CD filled film is tested for complexation of residual organics in the test film. The / CD is found to complex the residual organics effectively in linear low-density polyethylene (LLDPE).

We have evaluated nine modified / -cyclodextrins and one ground / -cyclodextrin (granulometry 5 to 20 microns). The different modified cyclodextrins are acetylated, octanyl succinate derivative, ethoxyhexylglycidyl ether derivative, quaternary amine derivative, tertiary amine derivative, carboxymethyl derivative, succinylate, amphoteric and trimethylsilyl ether derivative. Each experimental cyclodextrin (1% loading by weight) is mixed with low density polyethylene (LLDPE) using a Littleford mixer and then extruded using a Brabender twin screw extruder.

LLDPE profiles with the nine modified cyclodextrins and ground cyclodextrin are examined under a light microscope at 50X and 200X magnifications. Microscopic examination is used to visually verify the compatibility between LLDPE resin and cyclodextrin. Of the ten cyclodextrin candidates tested, three (acetylated, octanyl succinate, and trimethylsilyl ether) are visually found to be compatible with the LLDPE resin.

Residual complexed film volatiles are measured using the cryocapture procedure to test the film sample with 5% / CD and three extruded profiles containing acetylated / CD, octanyl succinate / CD, and 1% trimethylsilyl ether (by weight ). The method consists of three separate stages; the first two are carried out simultaneously while the third, an instrumental technique to separate and detect volatile organic compounds, is carried out after the first and second. In the first stage, a pure, inert, dry gas is used to remove the volatiles from the sample. During the gas scrubbing step, the sample is heated to 120 ° C. The sample is primed with a substitute (benzene-d₆) immediately before analysis. Benzene-d₆ it serves

ES 2 201 270 T3 as a substitute for inner QC to correct each set of test data for retrieval. In the second stage, the volatiles separated from the sample are concentrated by freezing the compounds in the scrubber gas in a capped ampoule immersed in a liquid nitrogen trap. At the end of the gas wash step, an inner standard (toluene-d8) is injected directly into the capped vial and the vial is closed immediately. Method and system controls are interspersed with samples and treated in the same way as samples to monitor contamination. The concentrated organic components are then separated, identified and quantified by high performance gas chromatography / mass spectrometry (HRGC / MS) on the heated head. The results of the residual volatiles analysis are presented in the table below:

TABLE 1% complexation of volatiles

Identification of sample compared to control

Blown film with / 1CD 5% 80

Profile with 1% acetylated / 1CD 47

Profile with / ICD with 1% octanyl succinate 0

Profile with 1% trimethylsilyl ether 48

Profile with /! (')) Ground at 1% 29

In these preliminary classification tests, the derivatives of /! (')) Are shown to efficiently complex the traces of volatile organics inherent in the low-density polyethylene resin used to make the experimental film. In the LL) PE film with 5% β (), approximately 80% of the organic volatiles are complexed. However, all the films with β () (1% and 5%) show coloration (light brown) and odor. The color and odor problem is believed to be the result of direct decomposition of the () or impurities in the (). Two active odor compounds (2-furaldehyde and 2-furanmethanol) are identified in blown film samples.

) In the three candidates of modified compatible () (acetylated, octanylsuccinate and trimethylsilyl ether), it is shown that acetylated and trimethylsilyl ether () efficiently complex the traces of organic volatiles inherent in the LLDPE resin. With a 1% load of the acetylated / ICD and with trimethylsilyl ether (TMSE) the complexation of approximately 50% of the volatile organic compounds in the L) PE is shown, while the () with octanyl succinate does not complex the residual volatile compounds of LLDPE resin. Ground /! (')) Is found to be less effective (28%) than acetylated and TMSE-modified / 1CD.

A combination of permeants is used to measure DC function and performance. A combination is used to be realistic, as gasoline (mainly a mixture of aromatic hydrocarbons) and printing ink solvents (mainly a mixture of aliphatic hydrocarbons) are not made up of a single compound but are a mixture of compounds.

The aromatic permeant contains ethanol (20 ppm), toluene (3 ppm), p-xylene (ppm), o-xylene (1 ppm), trimethylbenzene (0.5 ppm), and naphthalene (0.5 ppm). The aliphatic permeant, a commercial paint solvent blend containing approximately twenty (20) individual compounds, is 20 ppm.

The permeation tester consists of two glass permeation cells or flasks with 1200 ml cavities (ambient cell or feed side) and 300 ml (sample cell or permeation side).

The performance of the experimental film is measured in the closed volume permeation device. The High Performance Gas Chromatograph (HRGC) powered by a Flame Ionization Detector (FID) is used to measure the change in cumulative penetrating concentration as a function of time. Compound concentrations on the sampling side are calculated from the response factor for each compound. The concentrations are recorded in parts per million (ppm) by volume. The cumulative penetrating concentration is plotted on the sampling side of the film as a function of time.

We prepared four experimental test tube films. Three of the films contain the / ICD with loadings of 1%, 3% and 5% (by weight) while the fourth is a control film made from the same batch of resin and additives but without the)? CD.

A second experimental technique is also followed to determine if the / ICD sandwiched between two control films will complex the organic vapors that permeate the layer. The experiment is performed by lightly dusting the / ICD between two sheets of control film.

The tests show that the control film performs better than the ICD loaded films. The results of the permeation tests also show that at a given concentration point, the higher the / 1CD loading, the poorer the barrier performance of the film. Test results for sandwiching / ICD between two control films show that / 1CD is twice as effective in reducing permeation vapors than control samples without / 1CD. This experiment supports the thesis that

ES 2 201 270 T3

CD does complex the permeable organic vapors in the film if the barrier qualities of the film are not modified during the manufacturing process, making the film a less effective barrier.

1% ySCD and TMSE film is slightly better than 1% acetylated / 1CD film (24% vs. 26%) at removing aromatic permeants at 72 ° F (22.22 ° C), but the addition of a larger quantity of modified CD does not seem to provide any further improvement.

For aromatic perneants at 105 ° F (40.56 ° C), both / 1CD with 1% TMSE and 1% acetylated / 1CD are approximately 13% more effective at removing aromatic perneants than at 72 ° F (22.22 ° C). In this case too, the 1% TMSE film is slightly better than the 1% acetylated conySCD film (36% vs. 31%) in removing aromatic permeants.

1% TMSE film is more effective initially at removing aliphatic permeants than 1% acetylated jSCD film at 72 ° F (22.22 ° C). But over the duration of the trial, the / 1CD with 1% TMSE is worse than the control while the 1% acetylated / ICl) removes only 6% of the aliphatic perneants.

We prepared two experimental aqueous coating solutions. One solution contains hydroxyethylated ySCD (35% by weight) and the other solution contains hydroxypropylated ySCD (35% by weight). Both solutions contain 10% acrylic emulsion comprising a polyacrylic acid dispersion of molecular weight of approximately 150,000 (Polysciences, Inc.) (15% by weight solids) as a film-forming adhesive. These solutions are used to hand coat test tube film samples by laminating two LLDPE films. Two different coating techniques are used. In the first technique, the two film samples are flattened with a slight stretch, then the coating is applied using a hand roller, and then the two films are laminated while they are stretched flat. Samples Rev. 1 they do not stretch during the layering process. Finally, all the coated samples are placed in a vacuum laminating press to remove air bubbles from between the sheets of film. The thickness of the film coatings is approximately 0.0005 inch (0.0127 mm). Subsequently, tests are carried out with these CD-coated films and hydroxymethylcellulose-coated control films.

The reduction of aromatic and aliphatic vapors by the hydroxyethylated / 1CD coating is greatest during the first several hours of vapor exposure and then decreases during the next 20 hours of testing. A greater elimination of aliphatic vapors than aromatic vapors is achieved by the coating of hydroxyethylated ySCD, it is believed that it is a function of the difference in their molecular size (that is, aliphatic compounds are smaller than aromatic compounds). Aliphatic permeants are reduced by 46% compared to the control over the 20 hour test period. The reduction of aromatic vapors is 29% compared to the control over the test period of 17 hours.

Rev. 1 coated hydroxyethylated jSCD reduces aliphatic perneants by 87% compared to control over the 20 hour test period. It is not known whether the method of coating the film is responsible for the additional 41% reduction over the other hydroxyethylated ySCD coated film.

The hydroxyethylated ySCD coating performs slightly better at removing aromatic perneants than the hydroxypropylated / ICD coating (29% vs. 20%) at 72 ° F (22.22 ° C).

Large-scale film experimentation section

Preparation of cyclodextrin derivatives

Example I

Acetyl ester of β-cyclodextrin

An acetylated jS-cyclodextrin is prepared containing 3.4 acetyl groups per cyclodextrin in the primary hydroxyl group (-OH).

Example II

Trimethylsilyl ether of β-cyclodextrin

Three liters of dimethylformamide are placed in a rotary evaporator fitted with a 4000 milliliter round bottom flask and under a nitrogen atmosphere, introduced at a rate of 100 milliliters of N2 per minute. 750 grams of jS-cyclo-dextrin are placed in the dimethylformamide. The jS-cyclodextrin is rotated, and dissolved in the dimethylformamide at 60 ° C. Once dissolved, the flask is removed from the rotary evaporator and the contents are cooled to approximately 18 ° C. To the flask, located on a magnetic stirrer and fitted with a stir bar, 295 milliliters of hexamethyldisilylazine (HMDS-Pierce Chemical # 84769) are added followed by the careful addition of 97 milliliters of trimethylchlorosilane (TMCS-Pierce Chemical # 88531). The careful addition is accomplished by the careful dropwise addition of an initial 20 milliliter charge and after the reaction has calmed down the careful dropwise addition of other 20 milliliter portions etc., until the addition is complete. Finished adding TMCS, and calm

In the reaction, the flask and its contents are placed on the rotary evaporator, heated to 60 ° C while maintaining an inert nitrogen atmosphere flow of 100 milliliters of N2 per minute through the rotary evaporator. The reaction continues for four hours followed by removal of the solvent, leaving 308 grams of dry material. The material is removed from the flask by filtration, the filtrate is washed with deionized water to remove the silylation products, dried in a vacuum oven (75 ° C at 0.3 inch Hg) and stored as powdered material and it is kept for later mixing with a thermoplastic material. Subsequent spectrographic inspection of the material shows that β-cyclodextrin contains approximately 1.7 trimethylsilyl ether substituents per molecule of β-cyclodextrin. The substitution appears to be usually located on a primary 6-carbon atom.

Example III

A β-cyclodexlrin is prepared, hydroxypropylated with 1.5 hydroxypropyl groups per glucose molecule on the primary 6-OH group of the βCD.

Example IV

A β-cyclodextrin is prepared, hydroxyethylated with 1.5 hydroxyethyl groups per glucose molecule on the primary 6-OH group of βCD.

Film Preparation

To test the barrier properties of a barrier layer, we prepared a series of films using linear low-density polyethylene resin, βCD and derived βCD such as the acetylated or trimethylsilyl derivative of a β-cyclodextrin. Dry polymer particles are mixed with the β-cyclodextrin, and β-cyclodex-thermal material powder, a fluoropolymeric lubricant (3M) and the antioxidant until uniform in the dry mixture. The dry blended material is mixed and extruded into pellets in a Haake System 90 3/4 inch conical extruder. The resulting granules are collected for film preparation.

Table IA shows typical granulating extruder conditions. Films are blown into the apparatus as follows. A thermoplastic tube is extruded through a first row. The tube is then collapsed in a second row and roll laminated to form the film. The extruded tube is then inflated using pressurized air blown through an air inlet tube. The thermoplastic material is melted in the extruder. The temperature of the extruder in the mixing zone is taken. The temperature of the melt in the melting zone is taken at the same time that the temperature of the die is taken in the die. The extrudate is cooled using a stream of cooling air blown from a cooling ring. The above general description is representative of the Kiefel blown film extruder, with a 40mm diameter die, used in actual blown film preparation. The film is manufactured according to the protocol set forth above and the data is given in Table IB. The film is tested for transmission rates under a variety of environmental conditions. The environmental test conditions are given below in Table II.

TABLE IA

0.5% TMSE Granulation 1-19-94

<td>Test duration</td><td>0 min 13 sec</td><td>Twist Total twist</td><td colspan="3">4866 meter / gram 0.0 mkg / min</td><td>Rotor assistant</td><td>198 rpm 0%</td>

<td>Channels</td><td> -1-</td><td> -2-</td><td> -3-</td><td> -4-</td><td> -5-</td><td> -6-</td><td></td>

<td>Temp. of the melt</td><td> 37</td><td> 41</td><td> 41</td><td> 41</td><td> 41</td><td></td><td>° c</td>

<td>Temp. fixed</td><td> 150</td><td> 160</td><td> 160</td><td> 170</td><td> 0</td><td> 0</td><td>° c</td>

<td>Deviation</td><td> 0</td><td> 0</td><td> 0</td><td> 0</td><td> 0</td><td> 0</td><td>° c</td>

<td>Refrigeration</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td></td><td></td><td></td>

<td>Pressure</td><td> 0</td><td colspan="2"> 0 2739</td><td> 0</td><td> 0</td><td></td><td>psi</td>

ES 2 201 270 T3

<img file="ES2201270T3_D0002.tif" />

It also contains 500 ppm of the antioxidant Irganox 1010 and 1000 ppm of IrgaFos 168

TABLE IB

Extruded Films (Exxon LL3201) Produced with Low Density Polyethylene

ES 2 201 270 T3

The results of the tests show that the inclusion of a compatible cyclodextrin material in the thermoplastic films of the invention substantially improves the barrier properties by reducing the transmission rate of a variety of permeable fuel vapors. The data showing the improvement in the transmission rate is given below in the data tables below.

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient

<td></td><td></td><td>% improvement of</td><td>Regime</td><td>% improvement of</td>

<td>ID</td><td>Trans-</td><td>aromatics</td><td>transmission</td><td>total volatiles</td>

<td>of the sample</td><td>aromatics mission *</td><td>over control</td><td>total volatiles *</td><td>over control</td>

<td>Control film</td><td>3.35E-04</td><td> 0%</td><td>3.79E-04</td><td> 0%</td>

<td>1.0% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 2)</td><td>3.18E-04</td><td> 5%</td><td>3.61E-04</td><td> 5%</td>

<td>1.0% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 3)</td><td>2.01E-04</td><td> 40%</td><td>2.55E-04</td><td> 33%</td>

<td>1.0% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 5)</td><td>2.67E-04</td><td> 20%</td><td>3.31E-04</td><td> 13%</td>

<td>1.0% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 6)</td><td>3.51E-04</td><td> -5%</td><td>3.82E-04</td><td> -1%</td>

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient

<td>Sample identification</td><td>Aromatics transmission regime *</td><td>% improvement of gasoline over control</td>

<td>Control film (Roll # 1)</td><td>7.81E-03</td><td> 0%</td>

<td>0.5% CS-001 (Roll n ° 7)</td><td>7.67E-03</td><td> 2%</td>

<td>1% CS-001 (Roll n ° 5)</td><td>7.37E-03</td><td> 6%</td>

<td>2% CS-001 (Roll n ° 8)</td><td>6.53E-03</td><td> 16%</td>

* gm 0.001 in. 100 in.² · 24 h

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient

<td></td><td></td><td>% improvement of</td><td>Regime</td><td>% improvement of</td>

<td>ID</td><td>Trans-</td><td>aromatics</td><td>transmission</td><td>total volatiles</td>

<td>of the sample</td><td>aromatics mission *</td><td>over control</td><td>total volatiles *</td><td>over control</td>

<td>Control film</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 1)</td><td>5.16E-04</td><td> 0%</td><td>5.63E-04</td><td> 0%</td>

<td>1.0% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 5)</td><td>4.01E-04</td><td> 22%</td><td>5.17E-04</td><td> 8%</td>

<td>2.0% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 8)</td><td>2.91E-04</td><td> 44%</td><td>3.08E-04</td><td> 45%</td>

ES 2 201 270 T3

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient

<td>Identification of the sample</td><td>Aromatics transmission regime *</td><td>% improvement of gasoline over control</td>

<td>Control film (Roll # 1)</td><td>7.81E-03</td><td> 0%</td>

<td>0.5% CS-001 (Roll n ° 7)</td><td>7.67E-03</td><td> 2%</td>

<td>1% CS-001 (Roll n ° 5)</td><td>7.37E-03</td><td> 6%</td>

<td>2% CS-001 (Roll n ° 8)</td><td>6.53E-03</td><td> 16%</td>

* gm 0.001 in. 100 in.² · 24 h

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side: 0.25 Aw

Ambient side: 60% RH

<td>Sample identification</td><td>Aromatics transmission regime *</td><td>% improvement of aromatics over control</td><td>Total volatiles transmission rate ¹ *</td><td>% improvement in total volatiles over control</td>

<td>Control film (Roll # 1)</td><td>3.76E-04</td><td> 0%</td><td>3.75E-04</td><td> 0%</td>

<td>0.5% CS-001 (Roll n ° 7)</td><td>2.42E-04</td><td> 36%</td><td>2.41E-04</td><td> 36%</td>

<td>1% CS-001 (Roll n ° 5)</td><td>3.39E-04</td><td> 10%</td><td>3.38E-04</td><td> 10%</td>

<td>2% CS-001 (Roll n ° 8)</td><td>2.48E-04</td><td> 34%</td><td>2.47E-04</td><td> 34%</td>

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 105 ° F (40.56 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient% of improvement of% of improvement of

Identification Regime of aromatic trans-s Regime of transmission total volatiles of the sample aromatics mission * on control of total volatiles * on control

Control film

<td>(Roll n ° 1) 1% CS-001</td><td>1.03E-03</td><td> 0%</td><td>1.13E-03</td><td> 0%</td>

<td>(Roll n ° 2) 1% CS-001</td><td>5.49E-04</td><td> 47%</td><td>5.79E-04</td><td> 49%</td>

<td>(Roll n ° 3) 1% CS-001</td><td>4.74E-04</td><td> 54%</td><td>5.00E-04</td><td> 56%</td>

<td>(Roll n ° 4) 1% CS-001</td><td>6.41E-04</td><td> 38%</td><td>6.83E-04</td><td> 40%</td>

<td>(Roll n ° 5)</td><td>5.22E-04</td><td> 49%</td><td>5.54E-04</td><td> 51%</td>

1% CS-001

ES 2 201 270 T3 (Continued)

Temperature 105 ° F (40.56 ° C) Sampling side:% RH ambient

Ambient side:% RH ambient

<td>ID of the sample</td><td>Aromatics transmission regime *</td><td>% improvement of aromatics over control</td><td>Total volatiles transmission rate *</td><td>% improvement in total volatiles over control</td>

<td>(Roll n ° 6)</td><td>4.13E-04</td><td> 60%</td><td>4.39E-04</td><td> 61%</td>

<td>2% CS-001</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 8)</td><td>5.95E-04</td><td> 42%</td><td>6.18E-04</td><td> 45%</td>

<td>1% TMSE</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 12)</td><td>8.32E-04</td><td> 19%</td><td>8.93E-04</td><td> 21%</td>

* gm 0.001 in. 100 in.² · 24 h

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 105 ° F (40.56 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient

<td>ID of the sample</td><td>Aromatics transmission regime *</td><td>% improvement of aromatics over control</td><td>Total volatiles transmission rate *</td><td>% improvement in total volatiles over control</td>

<td>Control film (Roll # 1)</td><td>4.34E-04</td><td> 0%</td><td>4.67E-04</td><td> 0%</td>

<td>0.5% CS-001 (Roll n ° 7)</td><td>4.03E-04</td><td> 7%</td><td>4.41E-04</td><td> 6%</td>

<td>1.0% CS-001 (Roll n ° 5)</td><td>5.00E-04</td><td> -15%</td><td>5.33E-04</td><td> -14%</td>

<td>2.0% CS-001 (Roll n ° 8)</td><td>3.96E-04</td><td> 9%</td><td>3.94E-04</td><td> 16%</td>

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient% of improvement of% of improvement of

<td>ID of the sample</td><td>Aromatics transmission regime *</td><td>aromatics over control</td><td>Total volatiles transmission rate *</td><td>total volatiles over control</td>

<td>Control film</td><td>3.09E-04</td><td> 0%</td><td>3.45E-04</td><td> 0%</td>

<td>0.5% TMSE</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 13)</td><td>2.50E-04</td><td> 19%</td><td>2.96E-04</td><td> 14%</td>

<td>0.5% TMSE</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 14)</td><td>2.37E-04</td><td> 23%</td><td>2.67E-04</td><td> 33%</td>

<td>1% TMSE</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 9)</td><td>2.67E-04</td><td> 14%</td><td>3.05E-04</td><td> 12%</td>

1% TMSE

ES 2 201 270 T3 (Continued)

Temperature 72 ° F (22.22 ° C) Sampling side:% RH ambient Ambient side:% RH ambient

<td>Sample identification</td><td>Aromatics transmission regime *</td><td>% improvement of aromatics over control</td><td>Total volatiles transmission rate *</td><td>% improvement in total volatiles over control</td>

<td>(Roll n ° 10) 1% TMSE</td><td>4.85E-04</td><td> -57%</td><td>5.27E-04</td><td> -53%</td>

<td>(Roll n ° 11) 1% TMSE</td><td>2.58E-04</td><td> 17%</td><td>2.92E-04</td><td> 15%</td>

<td>(Roll n ° 12) 2% TMSE</td><td>2.15E-04</td><td> 31%</td><td>2.55E-04</td><td> 26%</td>

<td>(Roll n ° 15) 2% TMSE</td><td>2.54E-04</td><td> 18%</td><td>3.04E-04</td><td> 12%</td>

<td>(Roll n ° 16) 2% TMSE</td><td>2.79E-04</td><td> 10%</td><td>3.21E-04</td><td> 7%</td>

<td>(Roll n ° 17)</td><td>2.81E-04</td><td> 9%</td><td>3.24E-04</td><td> 6%</td>

* gm 0.001 in.

100 in.² · 24 h

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient

Ambient side:% RH ambient

Identification of Transmission Regime% improvement of the sample of aromatics * naphtha over control

Control Film (Roll # 1) 9.43E-03 0%

1% TMSE (Roll n ° 12) 1.16E-02 -23%

2% TMSE (Roll n ° 15) 1.56E-02 -65%

Comparison of Transmission Regimes in Modified β-Cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient Side:% RH ambient

<td></td><td></td><td>% improvement of</td><td></td><td>% improvement of</td>

<td>ID</td><td>Trans-</td><td>aromatics</td><td>Transmission regime</td><td>total volatiles</td>

<td>of the sample</td><td>aromatics mission *</td><td>over control</td><td>total volatiles *</td><td>over control</td>

<td>Control film</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 1)</td><td>8.36E-04</td><td> 0%</td><td>9.05E-04</td><td> 0%</td>

<td>0.5% TMSE</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 14)</td><td>6.77E-04</td><td> 19%</td><td>7.25E-04</td><td> 20%</td>

<td>2% TMSE</td><td></td><td></td><td></td><td></td>

<td>(Roll n ° 15)</td><td>6.36E-04</td><td> 24%</td><td>6.81E-04</td><td> 25%</td>

* gm 0.001 in. 100 in.² · 24 h

ES 2 201 270 T3

Comparison of Transmission Regimes in Modified / -cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side: 0.25 Aw Ambient side: 60% RH

<td>Sample identification</td><td>Aromatics transmission regime *</td><td>% improvement of aromatics over control</td><td>Total volatiles transmission rate *</td><td>% improvement in total volatiles over control</td>

<td>PVdC Control</td><td>6.81E-05</td><td> 0%</td><td>1.05E-04</td><td> 0%</td>

<td>PVdC w / 10% HP</td><td></td><td></td><td></td><td></td>

<td>B-CyD</td><td>1.45E-05</td><td> 79%</td><td>2.39E-05</td><td> 77%</td>

<td>PVdC w / 20% HP</td><td></td><td></td><td></td><td></td>

<td>B-CyD</td><td>9.71E-05</td><td> -42%</td><td>1.12E-04</td><td> -7%</td>

Comparison of Transmission Regimes in Modified / -cyclodextrin - LDPE Films

Temperature 72 ° F (22.22 ° C)

Sampling side:% RH ambient Side:% RH ambient

<td>Sample identification</td><td>Aromatics transmission regime *</td><td>% improvement of aromatics over control</td><td>Total volatiles transmission rate *</td><td>% improvement in total volatiles over control</td>

<td>Acrylic control</td><td>2.07E-06</td><td> 0%</td><td>2.10E-05</td><td> 0%</td>

<td>5% HP B-CyD /</td><td></td><td></td><td></td><td></td>

<td>Acrylic</td><td>1.50E-06</td><td> 27%</td><td>2.07E-05</td><td> 1%</td>

<td>10% HP B-CyD /</td><td></td><td></td><td></td><td></td>

<td>Acrylic</td><td>4.13E-06</td><td> -100%</td><td>4.30E-05</td><td> -105%</td>

* gm 0.001 in. 100 in.² · 24 h

We prepare a series of aqueous coatings containing hydroxypropylated / CD. One of the coatings is prepared from a 10% acrylic emulsion (a polyacrylic acid polymer with a molecular weight of approximately 150,000 purchased from Polysciences, Inc.). The 10% acrylic emulsion contains the hydroxypropylated / CD with a loading of 5% and 10% by weight. These solutions are used to hand coat test tube film samples by laminating two films. Coatings are applied to a sheet of linear low-density polyethylene film containing 0.5% acetylated CD (Roll # 7) and to a second sheet of film containing a / 2% acetylated CD (Roll # 8) using a hand roller and laminating the films next. Films do not stretch during lamination. All coated samples are placed in a vacuum laminating press to remove air bubbles from between the sheets of film. The thickness of the acrylic coating is approximately 0.0002 inches (0.0051 mm). A control coated with the acrylic emulsion is prepared identically but without hydroxypropylated / CD content. The multilayer structure is tested by looking at the 0.5% acetylated / CD film to the ambient flask side of the test cell.

A second coating is prepared from vinylidene chloride latex (PVDC, 60% by weight solids) purchased from Dagax Laboratories, Inc. The PVDC latex coating is prepared with two levels of hydroxypropylated / CD - 10% and 20% by weight of the derivatized cyclodextrin. These solutions are used to coat samples of linear low-density polyethylene test film by hand, joining the two films by laminating. Coatings are applied to two sheets of control film (rolled into one) using a hand roller and laminated together. Films will not stretch during the laminating process. All coated samples are placed in a vacuum laminating press to remove air bubbles from between the sheets of film. The thickness of the PVDC coating is approximately 0.0004 inch (0.01 mm). A PVDC coated control is prepared identically but without hydroxypropylated / CD.

We believe that films, coatings, and pattern laminates accurately predict the performance of fuel vapor barrier structures from CD-containing fuel containers.

ES 2 201 270 T3

The data presented below from the preparatory examples showing an improvement in the transmission rate are obtained using the following general test method.

Method summary

This method involves experimentation techniques designed to measure the permeability of selected organic molecules through food packaging films, using a static concentration gradient. The test methodology simulates accelerated shelf life test conditions by implementing various levels of warehouse humidity, product water activities, and temperature conditions and using concentrations of organic molecules found in previously tested food products to simulate organic vapors outside. -of-the-container in the permeation test cell. This procedure allows the determination of the following compounds: ethanol, toluene, p-xylene, o-xylene, 1,2,4-trimethylbenzene, naphthalene, naphtha solvent mixtures, etc.

TABLE 1

Permeation test compounds

<td>Environmental test compounds</td><td>Threshold odor concentration μ ^ ppm</td><td>Concentration in cell μ l / l ppm</td>

<td>ethanol</td><td> 5 - 5000</td><td> 20</td>

<td>toluene</td><td> 0,10 - 20</td><td> 3</td>

<td>p-xylene</td><td> 0,5</td><td> 2</td>

<td>o-xylene</td><td> 0,03 - 12</td><td> 1</td>

<td>1,2,3-trimethylbenzene</td><td>NA</td><td> 0,5</td>

<td>naphthalene</td><td> 0,001 - 0,03</td><td> 0,5</td>

<td>Naphtha Solvent Blend</td><td>NA</td><td> 40</td>

In a typical permeation experiment, three stages are involved. These are: (a) calibration of the sensitivity of the instruments, (b) tests of the films to measure the rates of transmission and diffusion and (c) the quality control of the permeation experiment.

Film samples are tested in a closed volume permeation device. High Performance Gas Chromatography (HRGC) powered by a Flame Ionization Detector (FID) is used to measure the change in cumulative penetrating concentration as a function of time.

The concentrations of the test compound on the sampling side and on the ambient side are calculated from the response factor or calibration curve for each compound. The concentrations for each specific set of permeation cells are then volume corrected if the mass of the permeant is desired.

Cumulative penetrating concentration versus time is plotted on both the upstream (ambient) and downstream (sampling) side of the film. The diffusion rate and transmission rate of the permeant are calculated from the permeation curve data.

1.0. Equipment and reagents

1.1 Equipment

Gas chromatograph (HP 5880) equipped with flame ionization detector, heated six port sampling valve with 1 ml sampling loop and data integrator.

J&amp;W capillary column. DB-5, 30M x 0.250mm ID 1.0 umdf.

Glass permeation test cells or flasks. Two glass bottles with cavities of approximately 1200 ml (ambient cell or feed side) and 300 ml (sampling bottle or permeation side).

Permeation cell holding rings (2).

Permeation cell aluminum sealing rings (2).

Natural rubber partitions: standard wall 8mm OD or 9mm OD (Aldrich Chemical Company, Milwaukee, WI).

Assortment of laboratory glassware and syringes.

ES 2 201 270 T3

Various laboratory consumables.

1.2 Reagents

Water for reagents. Water in which no interference is observed in the CDM of the chemical analytes of interest. A water purification system is used to generate reagent water that has been boiled to 80% volume, capped, and allowed to cool to room temperature before use.

Stock solution of ethanol / aromatic standard. Package of ethanol (0.6030 grams), toluene (0.1722 grams), p-xylene (0.1327 grams), o-xylene (0.0666 grams), trimethylbenzene (0.0375 grams) and naphthalene (0, 0400 grams) in 1 ml sealed glass ampoules. The standard naphtha blends is a commercial paint solvent blend containing approximately twenty (20) individual aliphatic hydrocarbon compounds, obtained from Sunnyside Corporation, Consumer Products Division, Wheeling IL.

Triton X-100. Nonylphenol nonionic surfactant (Rohm and Hass).

2.0 Preparation of the standards

2.1 Permeation working pattern

A stock solution of the permeant test tube standard is used. These standards are prepared by weight from certified undiluted reference compounds, actual weights and weight percentages are given.

The working ethanol / aromatic standard solution is prepared by injecting 250 μl of the stock standard solution into 100 ml of reagent water containing 0.1 grams of surfactant (Triton X-100). It is important that the Triton X-100 is completely dissolved in the reagent water before adding the permeant stock standard. This will ensure the dispersion of the test compounds in the water. Additionally, the working standard must be thoroughly mixed each time an aliquot is dispensed. It is advisable to transfer the working standard to rivet-neck vials with no clearance to minimize losses due to the large clearance in the volumetric flask used to prepare the standard.

A working naphtha mix standard is prepared by injecting 800 µl of the “undiluted” naphtha solvent mix into 100 milliliters of reagent water containing 0.2 grams of surfactant (Triton X-100).

An open stock standard solution should be transferred from the snap-cap glass vial to a rivet-top vial for short-term storage. The vials can be stored in an explosion-proof refrigerator or freezer.

2.2 Calibration standards

Calibration standards are prepared at a minimum of three concentration levels by adding volumes of the working standard to a volumetric flask and diluting to volume with reagent water. One of the standards is prepared at a concentration near, but above, the detection limit of the method. The other concentrations correspond to the expected range of concentrations found in the ambient and sample side cells.

3.0 Sample preparation

3.1 Preparation of film samples

The room bottle and sample bottle are washed in soapy water before use, rinsed thoroughly with deionized water, and oven dried. After cleaning, a rubber septum is applied to each bottle.

Cut the test film sample to the inside diameter of the aluminum sealing ring using a template. The diameter of the test film sample is important to prevent diffusion losses along the cut marginal circumference. The film sample, aluminum seals, and test bottle are assembled.

The test cell is prepared. First, the sample bottle and room bottle are flushed with dry compressed air to remove moisture from the sample and room bottles. This operation is performed by puncturing the septum of the sampling and ambient system with a needle and tube assembly that allows a controlled flow of dry air simultaneously through both vials. The clamping rings are loosely mounted on the jars to eliminate a pressure build-up on one side or the other of the film. After flushing both bottles for about 10 minutes, the needles are removed and the clamping rings are tightened, sealing the film between the two bottles. Rubber lined aluminum spacers are used to ensure a gas tight fit.

2 μl of water is injected per 300 ml of vial volume on the sampling side. Since the sampling flasks are of various volumes, the water varies to correspond to the variations in volume. The 2 μl of water in the 300 ml bottle volume is comparable to a product of water activity of 0.25 at 72 ° F (22.22 ° C). TO

ES 2 201 270 T3 40 μl of the ethanol / aromatic working standard or 40 μl of the working standard of the gasoline mixtures prepared as described in section 2.1 are then injected into the ambient flask. Any of these working standards will produce a relative humidity of 60% at 72 ° F (22.22 ° C) with a concentration of permeant (parts per million by volume) in the 1200 mL volume bottle indicated in Table I. Other moisture levels or permeant concentrations can be employed in the test method by using a psychrometric chart to determine moisture and using gas loss to calculate the permeant concentration. The time is noted and the permeation cell is placed in a thermostatically controlled oven. Samples can be spaced to suit the duration of the gas chromatography. Three identical permeation devices are prepared. Triplicate analyzes are used for QC purposes.

At the end of each time interval, a sample of the group is removed from the oven. The room flask is first analyzed using a heated six port sampler valve fitted with a 1 ml loop. The loop is flushed with a volume of 1 ml of the air from the ambient side or the sampling side. The loop is injected into the capillary column. The GC / FID system is started by hand following injection. Up to eight 1 ml sample injections can be taken from the sampling side and the ambient side of a single permeation experiment.

The sample-side and ambient-side test compound concentrations are calculated from the calibration curve or response factor for each compound (Equation 1 or 3). The volume concentrations for each specific set of permeation flasks are then corrected if the mass of the permeant is desired.

4.0 Sample analysis

4.1 Instrument parameters

Standards and samples are analyzed by gas chromatography using the following method parameters:

Column: J&amp;W column, DB-5, 30M, 0.25mm inner diameter, 1 umdf

Carrier: hydrogen

Split breather: 9.4 ml / min

Injection port temperature: 105 ° C

Flame detector temperature: 200 ° C Oven 1 temperature: 75 ° C

Program regime 1: 15 ° C

Oven 2 temperature: 125 ° C Regime 2: 20 ° C

Final oven temperature: 200 ° C

Final residence time: 2 min.

Set the temperature of the six port sampling valve to 105 ° C.

4.2 Calibration

A three-point calibration is prepared using standards in the range of the following test-tube compounds:

Test tube compounds

Calibration curve range ppm μl ethanol 2 - 20 toluene 0.3 - 3 p-xylene 0.2 - 2 o-xylene 0.1 - 1

1,2,4-trimethylbenzene 0.05 - 0.5

Naphthalene 0.05 - 0.5

Naphtha Solvent Blend 4.0 - 40

To prepare a calibration standard, an appropriate volume of the working standard solution is added to an aliquot of reagent water in a volumetric flask.

ES 2 201 270 T3

4.2.1 Secondary dilutions of working standards for the calibration curve

5 to 1 dilution: Put 5 ml of the working standard in a 25 ml volumetric flask, stopper, and then mix by inverting the flask.

2.5 to 1 dilution: Put 10 ml of the working standard in a 25 ml volumetric flask, stopper, and then mix by inverting the flask.

Analyze each calibration standard and tabulate the response of the compound peak area against the concentration of the test compound in the ambient side cell. The results are used to prepare a calibration curve for each compound. The Naphtha Solvent Blend is a commercial paint solvent containing approximately twenty (20) individual aliphatic hydrocarbon compounds. The response versus concentration is determined by summing the total of the areas under each of the twenty individual peaks. The least squares method is used to fit a line to the calibration curve. The slope of the calibration curve for each test compound is then calculated to determine the unknown concentration. The mean response factor can be used instead of the calibration curve.

The working calibration curve or response factor should be verified each business day by measurement of one or more of the calibration standards. If the response of any compound varies by more than 20%, the assay must be repeated using a new calibration standard. If the results still do not agree, generate a new calibration curve.

4.3 Analysis of the calibration curve and detection level samples of the method

The recommended chromatographic conditions are summarized above.

Calibrate the system daily, as above.

Check and adjust split breather rate and check rate with soap film flow meter.

To generate accurate data, the method's samples, calibration standards, and detection level samples must be run under identical conditions.

Calibration Standards and Method Detection Samples are prepared in the room bottle only. This is accomplished by using a 1/2-inch (12.7 mm) plastic disc and aluminum foil disc whose diameter is that of the environmental flange instead of the sampling bottle. A single sealing ring is placed on the flange of the glass room bottle followed by an aluminum foil, followed by the plastic disk.

The ambient flask is flushed with dry compressed air to remove moisture from the sampling and ambient flasks. This operation is performed by puncturing the septum of the room bottle with a needle and tube assembly that allows a controlled flow of dry air through the bottle. Clamping rings are loosely mounted on the bottle to eliminate pressure build-up. After flushing both vials for about 10 minutes, the needle is removed and the clamping rings are tightened, sealing the aluminum foil against the sealing ring.

40 μl of the ethanol / aromatic permeation working standard or secondary dilutions of the working standard are then injected into the room flask. Alternatively, 40 µl of the naphtha solvent mix or secondary dilutions of the working standard are injected into the room flask. The time is noted and the flask is placed in an oven equipped with a thermostatic control.

After 30 minutes, remove the ambient flask from the oven. The room flask is analyzed using a heated six port sampling valve fitted with a 1 ml loop. The loop is flushed with a volume of 1 ml of the air from the ambient side or the sampling side. The loop is injected into the capillary column. The GC / FID system is started manually following injection.

4.4 Calculation of results

4.4.1 Response factor of the test compound

The sample-side and ambient-side test compound concentrations are calculated for the slope of the calibration curve or response factor for each compound (RF). The volume concentrations for each specific set of permeation cells are then corrected if the mass of the permeant is desired.

Compound concentration in ppm =

Area under peak Slope of calibration curve (1)

ES 2 201 270 T3

Compound specific RF =

Compound concentration in ppm

Area under peak

Compound concentration in ppm = Area under peak x RF (2) (3)

Cumulative penetrating mass versus time is plotted on both the upstream (ambient) and downstream (sampling) side of the film. The diffusion rate and area transmission rate of the permeant are calculated from the permeation curve data.

4.4.2 Transmission regime

When a permeant does not interact with the polymer, the permeability coefficient, R, is usually characteristic of the permeant-polymer system. This is the case for the permeation of many gases, such as hydrogen, nitrogen, oxygen, and carbon dioxide, through many polymers. If a permeant interacts with polymer molecules, which is the case for the permeate test-tube compounds used in this method, P is no longer constant and may depend on pressure, film thickness, and other conditions. In such cases, a single value of P does not represent the characteristic permeability of the polymeric membrane and it is necessary to know the dependence of P of all possible variables to obtain the complete profile of the permeability of the polymer. In these cases, the transmission rate, Q, is often used for practical purposes, when the saturated vapor pressure of the permeant is applied at a specific temperature through the film. The permeability of films to water and organic compounds is often expressed as follows:

(Amount of permeant) (Film thickness) (Area) (Time) (Pressure drop through film) q = (Amount of permeant) (Film thickness) (Area) (Time)

In this application Q is represented in units of:

(4) (5) gm 0.001 inch (0.025mm)

100in.²(0.0645m²) · day

One of the main variables in determining the permeation coefficient is the pressure drop across the film. Since the transmission rate Q does not include either the pressure or the concentration of the permeant in its dimensions, it is necessary to know either the vapor pressure or the concentration of the permeant under the measurement conditions to correlate Q to P.

The pressure drop across the film from the ambient side to the sampling side is mainly due to the water vapor pressure. The water or moisture concentration does not remain constant and is not measured during the time intervals that organic compounds are analyzed, and therefore the pressure across the membrane is not determined.

The above examples of thermoplastic films containing a variety of compatible cyclodextrin derivatives show that the invention can be carried out on a variety of different thermoplastic films. In addition, a variety of different compatible derivatized cyclodextrin materials may be employed in the invention. Finally, films can be made using a variety of film-making techniques, including extrusion and aqueous dispersion coating to produce useful barriers. By any permeating fuel or other component.

In the foregoing specification, examples of substituted cyclodextrin, extruded thermoplastic materials containing the cyclodextrin, and test data showing structures provided with improved fuel vapor barriers provide a basis for understanding the technical aspects of the invention. However, since the invention can be practiced with a variety of embodiments, the invention resides in the claims appended below.