Membranes made of polyurethane-based materials containing polyol esters

The present invention relates to a polyurethane membrane based on a polyol polyester with limited gas diffusion through the membrane. Furthermore, the invention relates to a method for producing a laminated membrane with limited gas diffusion, usually present in the atmosphere.

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Membranes, or more precisely membranes suitable for the retention of liquids, including liquids and / or gases in a controlled manner have been used in many products for years, from inner tubes used in gas-filled objects, including e.g. vehicle tires and sporting goods, through shock absorbers used in heavy machinery, for cushioned inserts in footwear. Regardless of the intended application, the membranes must generally be flexible, resistant to environmental degradation and provide excellent control of gas passage. However, typically materials with adequate flexibility have an unsatisfactorily low level of gas permeability. On the other hand, materials showing an adequate level of resistance to gas penetration do not have sufficiently high flexibility.

In US Pat. No. 5,036,10 an attempt to reconcile the requirement of flexibility and gas impermeability is proposed by proposing elastic membranes for filling hydropneumatic shock absorbers. The described membrane is composed of a film made of a graft polymer, which is a reaction product of an aromatic thermoplastic polyurethane with a copolymer of ethylene and vinyl alcohol, which film is placed between the layers of thermoplastic polyurethane, forming a laminate. Although it has been possible to some extent to solve the problem of flexibility and gas impermeability, the significant disadvantage remains that the described film does not undergo treatment using traditional techniques such as e.g. sheet extrusion. In contrast, the present invention relates to membranes that are flexible, have good resistance to gas passage and can be processed, using traditional techniques such as sheet extrusion, into laminates that are very resistant to delamination.

The membranes of the present invention have a wide range of applications from blisters used in gas filled objects such as American footballs, basketballs, footballs, inner tubes; rigid floating equipment such as boat hulls; flexible floating equipment such as inflatable boats or rafts; as components of medical equipment such as balloon catheters; fuel lines and fuel tanks; various types of cushioning, being parts of footwear or clothing articles; parts of furniture, such as chairs and seats, parts of bicycles and saddles, parts of protective equipment including shin guards or helmets; elements of furniture backs, in particular loins; parts of prostheses and orthopedic equipment; parts of vehicle tires, in particular the outer layers of these tires; as well as being part of some type of recreational equipment, such as the components of roller skates and roller skates, to name some of the applications, while other applications are possible. For example, one particularly desirable application of the membranes of the invention is their use in the manufacture of shock absorbers capable of operating under high pressure conditions, such as hydraulic shock absorbers, described in more detail below.

For simplicity, without limiting the scope of the invention, the membranes are described below as shock absorbers or, because of yet another highly desirable application, as shock absorbers used in footwear. For a broader discussion of the use of membranes for cushioned insoles for footwear, general characteristics of footwear seem necessary.

The term footwear, or more specifically shoes, essentially includes two main components, namely the top of the shoe and the sole. In general, the top of the shoe is used to comfortably embrace the foot. Ideally, the top of the shoe should be made of an attractive, comfortable but durable material, or a combination of such materials. The sole, which can also be made of at least one durable material, is specifically designed to provide traction and protect the user's foot and body during use. Significant forces generated during sports exercises require that the sole of a sports shoe provides the user's feet, ankles and legs with increased protection and shock absorption. For example, running shocks can generate forces up to 2-3 times the weight of a person, while the forces generated during some other exercises, such as playing basketball, can reach values ​​about 6-10 times the weight the person's body '. Therefore, many types of shoes, in particular sports shoes, are currently equipped with some kind of elastic, shock-absorbing

187 071 material or with shock-absorbing ingredients to protect the user during strenuous sports activities. Such elastic, shock-absorbing materials or components are now commonly referred to as cushioning pads in the footwear industry.

For this reason, the focus of the footwear industry is focused on finding a solution filled with a fluid, either in the form of liquid or gas, or both. Examples of gas-filled structures used in the soles of shoes are described in patents: No. US 900.867 entitled Soft insole for shoes from 1908; US 1.069.001 entitled Cushioning sole and heel of the shoe '; US 1,304,915 entitled Pneumatic insert; Us 1.514.468, entitled Shock absorber supporting the instep; US 2.080.469, entitled Pneumatic foot support; US 2,645,865 entitled Cushioned insole; US 2,677,906, entitled Cushioning insole for a shoe sole and method of its production; US 4,183,156, entitled Design of insoles for footwear articles; US 4,219,945, entitled Footwear; US 4,722,131, titled Shoe Sole with cushioned insole, and US 4,864,738, titled Shoe Sole Structure. Those skilled in the art generally subdivide such gas-filled structures, often referred to as blisters in the footwear industry, into two broad categories, namely (1) systems permanently filled with fluid, such as those described in U.S. Patent Nos. 4,183,156 and 4,199,945 ) pump and valve controlled systems described in US Patent 4,722,131. By way of further example, sports shoes of the type described in U.S. Pat. No. 4,182,156 containing permanently inflated blisters are successfully sold under the trademark Air-Sole by Nike, Inc. from Beaverton, Oregon. To date, millions of pairs of sports shoes of this kind have been sold in the United States and around the world.

In the past, permanently inflated blisters were produced by methods that utilized flexible thermoplastic materials that were filled with gas with large molecules, with low solubility coefficient, referred to in this industry as super gas. For example, in US Patent 4,340,626 entitled Diffusion Pumping Apparatus describes selectively permeable film sheets that are formed into bubbles and then filled with a gas or gas mixture to the recommended pressure, which generally exceeds atmospheric pressure. The gas used should have a relatively low diffusion rate through this selectively permeable membrane to the external environment, while gases such as nitrogen, oxygen and argon, which are contained in the atmosphere and have a relatively high diffusion rate, are able to penetrate this bladder. This gives an increase in the total pressure in the bladder, by adding up the partial pressures of nitrogen, oxygen and argon from the atmosphere, with the partial pressures of the gas or gases initially injected into the bladder during their filling. The concept of relatively unidirectional gas addition to increase total bladder pressure is now known as diffusion pumping.

Regarding the systems used in the footwear industry before and shortly after the introduction of Air-Sole sports shoes, many of the cushioning pads consisted of a single-layer gas barrier film made of polyvinylidene chloride materials such as Sarni (a trademark of Dow Chemical Co .), which in their nature are rigid plastics, having relatively low bending strength, susceptibility to thermal welding and flexibility.

In addition, bladder films made by techniques such as lamination and coating, having one or more separating materials in combination with a flexible bladder material (e.g., thermoplastic), can potentially present a wide range of problems that need to be solved. Such problems associated with the use of composite systems include, but are not limited to, separation of layers, flaking, gas diffusion or capillary phenomena at the weld border, high elongation factor causing wrinkling of the gas-filled product, turbidity of finished blisters, reduced puncture resistance and tear resistance, difficulty in manufacturing by method

187 071 extrusion blow molding and / or hot sealing and high frequency welding, significant manufacturing costs and difficulties in closing pores and gluing.

Another issue concerning previously known multi-layer blisters is the use of binding materials or adhesives in the production of laminates. The use of binding materials or adhesives generally does not allow the milling and processing of waste generated in the process of forming the product into consumer products, thus contributing to high manufacturing costs and relatively large losses. These and other perceived disadvantages of prior art solutions are described in more detail in US Patent Nos. 4,340,266, US 4,936,029 and 5,042,176.

Regarding the previously known multilayer blisters in which adhesive binding layers have been intentionally eliminated, they are known to undergo separation or delamination. especially along the seams and edges. Therefore, recently industry attention has been focused on the development of laminated blisters with reduced or no delamination, preferably without the use of a tie layer. In this aspect, the devices described in U.S. Patent Application Nos. 08 / 299.286 and 08 / 299.297 eliminate adhesive bonding layers, resulting in membranes consisting of a first layer of thermoplastic urethane and a second layer consisting of a separation material such as a copolymer of ethylene vinyl alcohol and characterized by in that there is a hydrogen bond in the zone of these membranes between the first and second layers. Although the membranes described in the US Patent Application Series 08 / 299.287 and laminated flexible membranes from US Patent Application 08 / 299.286 are considered to be significant advances in this field, the present invention offers further improvement.

Along with the great commercial success of products such as Air-Sole® shoes, consumers could enjoy products with a long service life, better shock absorption and elasticity, a moderate price as well as pressure stability without having to resort to pumps and valves. Therefore, in view of the significant commercial success and acceptance achieved through the use of permanent gas-filled blisters, it is highly desirable to develop improvements for these products. One of the goals is therefore to provide flexible, permanently inflated gas-filled shoe pad components that match and optimally exceed the parameters obtained by products such as Air-Sole® sports shoes, offered by Nike, Inc.

The adopted method for measuring the relative permeance, permeability and diffusion of various films is described in the American standard ASTM D-1434-82-V. According to ASTM D-1434-82-V, permeance, permeability and diffusion are measured using the following formulas:

Permeancia (amount of gas) = ​​Permeance = cm³ (air) * (time) * (differential pressure) = (GTR) / (differential pressure) = (m²) (24 hours) (Pa)

Permeability (amount of gas) * (thickness of layers) = Permeability = (cm³) (mm) (above) * (time) * (differential pressure) (GTR) * (thickness layer) / (differential pressure) = (m²) (24 hours) (Pa)

Diffusion (gas quantity) = Gas Flow Rate = cm3 (area) * (time) GTR (m2) (24 hours)

Using the above equations, you can use the gas flow rate, in conjunction with the steel pressure difference and film thickness, to determine the gas flow under certain conditions. In this regard, the favorable gas transmission rate (GTR) for a membrane with an average thickness of about 0.05 mm, i.e. such as those that are suitable for forming a cushioning element used as part of a shoe, which is to meet stringent requirements regarding for endurance against fatigue caused by intense and repetitive strokes, it should preferably be 15.0 or

187 071 less for nitrogen according to ASTM D-1434-82-V. Even more preferably, these membranes should have a GTR of less than about 2.0 with an average thickness of 0.05 mm.

Therefore, one of the purposes of the invention is to obtain membranes, including both single-layer and multi-layer structures, giving greater flexibility, durability and resistance to undesirable passage of gases through them.

Another object of the invention is to obtain membranes, in particular those used as cushioning inserts, having a relatively high degree of transparency.

Still another object of the invention is to obtain single-layer membranes that can be easily processed into various products, and in some applications multi-layer membranes that can be recycled and repaired.

Still another object of the invention is to obtain membranes that could be processed into laminated objects, such as, inter alia, cushioning inserts or shock absorbers more resistant to delamination and at the same time not requiring a tie layer between these layers.

Still another object of the invention is to obtain membranes that do not allow gas to escape at the interface between the layers in the laminated joint, in particular along the seams, due to the capillary effect.

Still another object of the invention is to obtain membranes that enable the manufacture of footwear by incorporating the membrane in a moldable material.

Although the above-mentioned objectives give tips on possible applications and advantages of membranes, these objectives do not exhaust or limit other possible applications.

According to the invention, the polyurethane membrane based on a polyol polyester, with a limited diffusion rate, is made of a polyol based polyol polyurethane comprising a reaction product of a carboxylic acid containing not more than 6 carbon atoms and a diol containing not more than 6 carbon atoms in which repeating units Polyol polyester contain no more than 8 carbon atoms with a gas diffusion rate of not more than 15.0 with respect to nitrogen gas.

Preferably, in the membrane according to the invention, the polyol polyester is made from carboxylic acid from the group consisting of adipic acid, glutaric acid, succinic acid, malonic acid, oxalic acid and mixtures thereof, and from a diol from the group consisting of ethylene glycol, propanediol, butanediol, neopenthyldion, pentanediol, hexanediol and mixtures thereof.

In addition, said polyurethane further comprises at least one alcohol and amine extender, especially from the group consisting of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol and 1,6-hexanediol.

In this membrane, at least one of the extenders and at least one polyol polyester contain groups with active hydrogen atoms.

The ratio of polyester polyol to extender is generally in the range of 1: 0 to 1:12, preferably in the range of 1: 1 to 1: 8, while the ratio of isocyanate units contained in said polyurethane to groups containing active hydrogen atoms is preferably in the range from 0.95: 1 to 1.10: 1.

Said polyurethane in the membrane may further contain a hydrolytic stabilizer in an amount of up to 5.0% by weight, preferably from the group consisting of carbodiimides, polycarbodiimides and epoxidized soybean oil.

Further, said polyurethane may contain at least one plasticizer in an amount of up to 40% by weight, at least one ignition retarder in an amount of up to 40% by weight, at least one filler in an amount of up to 60% by weight, and at least one additive selected from the group consisting of antioxidants, UV stabilizers, light stabilizers, heat stabilizers, organic agents to facilitate mold removal, dyes, fungicides, release formers and glidants in an amount of up to 3.0% by weight.

In the membrane of the invention, said polyurethane may further comprise at least one triol, such as trimethylolpropane.

The membrane according to the invention may further comprise a barrier, being as matter! the barrier contains at least one polymer from the group consisting of ethylene vinyl alcohol copolymers, polyvinylidene chloride, acrylonitrile and methyl acrylate copolymer, polyethylene terephthalate

187 071 ethylene, aliphatic or aromatic polyamides, crystalline polymers and thermoplastic structural polyurethanes, the barrier being mixed with polyurethane before forming the membrane.

The membrane may contain a polyurethane based on a polyol polyester in an amount of up to 70% by weight. As a polymer, it contains at least one copolymer of ethylene and vinyl alcohol with 25-48 mole% ethylene.

A preferred membrane comprises at least one polyurethane having soft fragments from the group consisting of polyether polyethers and polyol polyesters formed by the reaction of carboxylic acid and diol, whose repeating units contain more than eight carbon atoms, and mixtures thereof. The polyurethane may contain up to 30% by weight of soft fragments selected from the group of polyol polyesters, polyol polyesters formed by the reaction of carboxylic acid and diol, whose repeating units contain more than eight carbon atoms, and mixtures thereof. Preferably, the polyol polyesters formed by the reaction of carboxylic acid and diol and containing more than eight carbon atoms are selected from the group consisting of ethylene glycol isophthalate, 1,4-butanediol isophthalate and 1,6 hexanediol isophthalate.

The membrane of the invention has a gas diffusion rate of less than 10.0, for example less than 7.5, preferably less than 5.0, more preferably less than 2.5, most preferably less than 2.0.

The membrane made of elastomeric material has an elongation at break of at least 250%, preferably from 250% to 700%, a tensile strength of at least 17,200 kPa. Further, it has 100% tensile modulus of 2400 to 20.700 kPa and has a hardness in Shora degrees from 60 A to 65 D, preferably from 80 A to 55 D, and from 85 A to 50 D, as determined by a hardness tester.

The preferred polyurethane used in the membrane of the invention is made of aromatic isocyanate, in particular diphenylmethane diisocyanate.

A preferred membrane contains not less than 50% by weight of at least one barrier material from the group consisting of ethylene vinyl alcohol copolymers, polyvinylidene chloride, copolymers of acrylonitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, crystalline polymers and thermoplastic polyurethane polyurethane, modified polyurethane before forming the membrane, from 1% to 50% by weight of at least one thermoplastic aliphatic polyurethane and up to 3% by weight of at least one thermoplastic aromatic polyurethane, based on the total composition of the mixed layer equal to 100% by weight.

The membrane as a thermoplastic aromatic polyurethane contains a polyurethane based on macroglycol from the group consisting of polyester, polyether, polycaprolactone, polyoxypropylene, polycarbonate and mixtures thereof. Preferably, said thermoplastic aromatic polyurethane is a polyurethane based on 1,4-diphenylmethane diisocyanate.

The membrane according to the invention forms the first layer of the multilayer structure. The multilayer structure further comprises, connected to the first layer, a second polymer layer from the group consisting of ethylene vinyl alcohol copolymers, polyvinylidene chloride, acrylonitrile and methyl acrylate copolymer, polyethylene terephthalate, aliphatic or aromatic polyamides, crystalline polymers and thermoplastic polyurethanes and their structural mixtures. The first and second layers are formed together so that a hydrogen bond exists between them.

The membrane is formed at least in part from a thermosetting polymer.

The resulting membrane has a durability of at least 200,000 cycles as analyzed by the KIM test, under conditions where the membrane is in the form of a closed container with an average wall thickness of 1.8 mm and is filled with nitrogen gas to a pressure of 138 kPa. Preferably the membrane has a durability of more than 750,000 cycles according to KIM test analysis.

The membrane has a yellowing index of less than 4.0, preferably not more than 1.6, with an average membrane wall thickness of 800 pm, has a light transmission degree of not less than 90.0% with an average membrane thickness of 800 pm.

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Generally, the membrane has an average thickness from about 125 pm to about 5000 pm, preferably, from about 375 pm to about 1000 µm.

The invention also includes a method for producing a laminated membrane designed to limit gas permeability, in which a first layer of polyurethane based on a polyol polyester is first extruded, then a second layer is extruded together with a first layer in which the material chosen for the second layer contains functional groups having hydrogen atoms capable of entering hydrogen bonds with the first polyurethane layer to form a membrane.

The membranes of the invention provide (1) the desired level of flexibility (or stiffness); (2) the desired level of resistance to moisture degradation; (3) an acceptable level of impermeability to liquids, which may be in the form of gases, liquids or both at the same time, depending primarily on the intended use of the product; and (4) delamination resistance when used in a multilayer structure. Regardless of the connection, each membrane according to the invention comprises a polyurethane layer based on a polyol polyester. This above-mentioned layer may also contain at least one separating material selected from the group consisting of ethylene vinyl alcohol copolymers, polyvinylidene chloride, copolymers of acrylonitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, crystalline polymers and thermoplastic polyurethane constructional blends polyurethane before making the membrane.

If the polyurethane-based urethanes used are not commercially available, they can preferably be prepared as a reaction product of (a) one or more carboxylic acid having six or fewer carbon atoms with one or more diols having six or fewer carbon atoms; (b) at least one isocyanate and / or diisocyanate; and (c) optionally but preferably one or more extension cords. The polyol polyester may also contain a relatively small amount of one or more polyfunctional materials, such as triols, which form part of the reaction products. In addition to the aforementioned, polyurethane-based polyols may optionally contain one or more of the following: (d) hydrolytic stabilizers; (e) plasticizers; (f) fillers; (g) flame retardants; and (h) ancillary measures. The resulting polyol polyesters formed as a result of the reaction of one or more carboxylic acids with one or more diols, preferably have repeating units having eight or fewer carbon atoms.

Unless otherwise specified, specify the carboxylic acid primarily carboxylic acid, or more specifically Zicarbexylic acid, having no more than six carbon atoms, capable of reacting with dieam, the repeat units of the polyol polyester formed in the above said reaction have no more than eight carbon atoms.

Unless stated), refer to PioI for all diols, not more than six carbon atoms capable of reacting with carboxylic acid, with the repeat units of the polyol polyester formed in the above-mentioned reaction having no more than eight carbon atoms.

The term polyester polyol means primarily oolymeric polyol polyesters having a molecular weight (determined by the ASTM D-4274 method) in the range from about 300 to about 4000; preferably from about 400 to about 2000; and even more preferably between about 500 to about 1500.

The term thermoplastic generally means that the material softens as a result of heating and hardens upon cooling in the characteristic temperature range, and that in the softened state it can be shaped into various products using various techniques.

The thermally crosslinked refining used generally means polymeric material, which, when fully reacted, does not flow under the influence of heat and pressure.

The term extender or bifunctional extension cord is used primarily in the generally accepted sense and includes glycols, diamines, aminealkeholes and the like. First of all, any such extension cord or bifunctional extension cord used in accordance with the invention will have a molecular weight generally in the range of from about 60 to about 400.

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The term "soft fragment" is used in general to mean a component of the composition having a molecular weight of from about 300-400, having, prior to the reaction, approximately two or more groups having active hydrogen atoms in the molecule, giving the resulting polymers elastomer properties.

It is desirable that the membranes described in the present invention are suitable for use as footwear components. For such applications, it is desirable that the membranes be able to keep the gas closed for a relatively long period of time. In a particularly preferred case, for example, the membrane should not lose more than about 20% of the gas pressure initially created within about two years. In other words, products initially filled with gas to a constant pressure between 135 kPa and 145 kPa should maintain pressures in the range of about 110 to 125 kPa for at least two years.

In addition, materials used for products such as sports shoe components should be flexible, relatively soft and flexible, and should have high fatigue strength and be weldable, giving effective welds, usually obtained by high frequency or thermal welding . Such material should be able to withstand high load variability without failure, especially when the material used is between about 5 millimeters to about 200 millimeters thick.

Another desirable characteristic of membranes is their susceptibility to processing into various shapes by means of large-scale production techniques. These techniques include, but are not limited to, extrusion, blow molding, injection molding, vacuum molding, stamping, pressure molding, thermal welding, casting, low pressure casting, vortex casting, reaction injection and high frequency welding.

As discussed above, a desirable feature of membranes with both single-layer and multi-layer structure is their susceptibility to processing into gas-filled products (such as cushioning inserts for footwear) and which limit gas diffusion through these membranes. Thanks to the invention, due to the properties of materials, not only super gases can be used as closed gases, but also nitrogen and air, among others.

Another advantage of the single-layer membranes of the invention is the elimination of many processing problems specific to multi-layer fittings. Single-layer membranes generally do not require special mechanical attachments for processing equipment or other process control components.

Regarding multilayer fittings, another advantage of the invention is the improvement of bonding between adjacent layers, potentially eliminating the need for adhesive layers. This so-called improved bonding is generally achieved by close contact between the first and second layers as a result of traditional techniques in which the material of both layers has functional groups with hydrogen atoms that can participate in hydrogen bonds, such as hydrogen atoms in hydroxyl groups or hydrogen atoms associated with atoms nitrogen in urethane groups and various receptor groups such as, for example, oxygen atoms in hydroxyl groups, carbonyl oxygen atoms in urethane groups and ester groups and chlorine atoms in PVDC. It is believed that a feature of this type of laminated membrane is that hydrogen bonding occurs between the first and second layers. For example, the theoretically described hydrogen bond occurs when the first layer contains a urethane based on a polyester polyol and the second layer consists of copolymers of ethylene and vinyl alcohol, polyvinylidene chloride, copolymers of acrylonitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, polymers crystalline and thermoplastic structural polyurethanes. In addition to the presence of hydrogen bond, theory predicts the presence of some covalent bonds between the first and second layers when, for example, adjacent layers contain polyurethanes or when one of the layers contains polyurethane and the adjacent layer contains a separating material such as ethylene vinyl alcohol copolymers.

The present invention has many advantages that will become more apparent upon consideration of the various forms and moldings. Similarly, although the fittings shown in the accompanying drawings are an illustration of fittings obtained from the membranes that are the subject of this

187 071 of the invention, it should be obvious that the possibilities of using these membranes are wider and the detailed description below should not be considered as limiting the invention.

The accompanying drawings show embodiments of the invention.

Figure 1 is a side elevational view of a sports shoe in which a fragment of the inner part of the sole has been cut out to show a cross section; Figure 2 is a bottom view of the vertical view of the sports shoe of Figure 1, part of which has been cut off to show the cross section; figure 3 is a section view along line 3-3 in figure 1.

Figure 4 is a partial perspective view of a tubular shaped body of a two-layer cushioning insert; figure 5 is a section view along line 4-4 in figure 4; Figure 6 is a partial perspective view of another tubular three-layer cushioning insert; Figure 7 is a side cross-sectional view taken along line 6-6 of Figure 6; Figure 8 is a perspective view of a membrane body according to the invention formed as a shoe cushioning insert; Fig. 9 is a side view of the membrane shown in Fig. 8; Figure 10 is a perspective view of a membrane body according to the invention formed as a shoe cushioning insert; Figure 11 is a side elevational view of a membrane molded article of the invention formed as a cushioning insert disposed in a shoe; Fig. 12 is a perspective view of the membrane of Fig. 11; Fig. 13 is a top plan view of the membrane shown in Fig. 11 and Fig. 12.

Figure 14 is a side elevational view of a membrane shaped body formed as a cushion insert placed in the shoe; Figure 15 is a perspective view of the membrane of Figure 14; Fig. 16 is a top view of the membrane shown in Fig. 14 and Fig. 15.

Figure 17 is a perspective view of a membrane shaped body according to the teachings of the invention formed as a cushioning shoe; Figure 18 is a side view of the membrane of Figure 17.

Figure 19 is a cross-sectional view of a product formed of the laminated membrane according to the invention; Fig. 20 is a cross-sectional view of another product made of the laminated membrane of the invention.

Figure 21 is a side elevational view of the plate coextrusion device; Figure 22 is a cross-sectional view of a manifold portion of the plate coextrusion device of Figure 21; Figure 23 is a side elevational view of the pipe coextrusion device.

Figure 24 is a cross-sectional view of a single-layer tubular membrane; and Fig. 25 is a cross-sectional view of a product formed from a single-layer membrane according to the invention.

Embodiments of the invention are set out below.

In Figs. 1-3, a sports shoe is shown, including the sole structure and the cushioning insole, as one example of a product made of the membrane of the invention. Shoe 10 has a top 12, to which a sole 14 is attached. Top 12 can be made of various traditional materials, including leather, vinyl, nylon and other, usually woven textiles. In a typical arrangement, the top 12 has reinforcements located around the toes 16, holes for laces 18, the top of the shoe 20 and around the heel 22. As with most sport shoes, the sole 14 extends substantially along the entire length of the shoe 10, from the toe area 20 through the area instep 24 and then to heel 22.

The illustrated sole structure 14 includes one or more selectively permeable cushioning pads or membranes 28, which are typically located in the middle of the sole structure. The membranes 28 according to the invention can be formed into articles of various geometrical shapes, for example, various tubular elements arranged separately, parallel to each other in the heel zone 22 of the middle part of the sole 26, as shown in Figs. 1-3. These tubular elements are embedded and contain injected trapped gas. The barrier properties of the membrane 28 are preferably provided by the single or single-layer 30A shaped body shown in Fig. 24 or by the layer 30 shown in Figs. 4-5 arranged along the inner surface of the thermoplastic outer layer 32. As shown in Figs. 8-18, membranes 28 according to the invention.

187 071 both single-layer and multi-layer fittings can be formed into a variety of products with multiple configurations or shapes. At this point, it should be noted that the membranes 28, formed into cushioning inserts used in footwear, can be fully or partially enclosed in the middle or outer part of the shoe sole.

Returning to Figures 1-3, the membrane 28 according to the invention is shown in the form of a cushion insert constituting a component of footwear. Membrane 28, in accordance with the shaped body shown in Fig. 24, comprises a single layer 30A formed of a urethane based on at least one polyol polyester. These polyol based urethanes are preferably formed as a reaction product of (a) one or more carboxylic acids having six or fewer carbon atoms with at least one diol having six or fewer carbon atoms; (b) at least one isocyanate or diisocyanate; and (c) optionally, but preferably, one or more extension cords. Optionally, the polyurethane-based urethanes may also contain one or more of the following: (d) hydrolytic stabilizers; (e) plasticizers; (f) fillers; (g) flame retardants; and (h) ancillary measures. As already mentioned, the polyol polyester is preferably formed as a reaction product of at least one carboxylic acid with at least one diol, the number of carbon atoms contained in the polyol polyester repeating units in the reaction product being eight or less. In addition to at least one diol, the reaction product may also contain small amounts of one or more polyfunctional materials, such as triols, i.e. not more than 5,0% equivalent, calculated on the sum of the reaction product and groups containing active hydrogen atoms.

Among the carboxylic acids believed to be useful in the formation of urethanes based on the polyol polyesters of the invention, mention may be made of adipic, glutaric, succinic, malonic, oxalic acid and mixtures thereof are considered particularly useful.

Among the diols believed to be useful in the formation of urethanes based on the polyol polyesters of the invention, mention may be made of ethylene glycol, propanediol, butanediol, neopentyl diol, pentanediol and hexanediol, and mixtures thereof are considered particularly useful. Among the triols considered to be useful in the formation of urethanes based on the polyols polyesters of the invention, mention may be made of trimethylolpropane.

In a preferred embodiment, the polyurethane-based urethanes used in forming the 30A layer. For single-layer applications and for multi-layer applications include ethylene glycol adipate. In this aspect, some commercially available ethylene glycol adipates such as FOMREZ⁰ 22-112 and 22-225, produced by Witco Chemical are considered useful.

Among the isocyanates, especially the diisocyanates used in accordance with the invention, mention may be made of isophorone diisocyanate (IPDI), methylene (bis 4-cyclohexyl) isocyanate (HnMDI), cyclohexyl diisocyanate (CHDl), hexamethylene diisocyanate (HDI) m-tisocyanate , p-tetra-methyloxylene diisocyanate (p-TMXDI) and xylene xylene diisocyanate (XDI) are considered useful; diphenylmethane diisocyanate (MDi) is particularly useful. Preferably, the isocyanate or isocyanates are used in a proportion such that the overall ratio of isocyanate equivalents to equivalents of materials containing active atoms in the water is in the range from 0.95: 1 to 1.10: 1, and more preferably 0.98: 1 to 1 04: 1. As is known, in the urethane chemistry the term groups containing active hydrogen atoms usually refers to groups including both amines and alcohols, capable of reacting with isocyanate groups.

Optionally, but often preferably, the polyurethanes based on the polyol polyesters of the invention contain hydrolytic stabilizers. For example, two commercially available carbodiimide based hydrolysis stabilizers, known as STABAXOL P and STABAXOL P-100, from Rhein Chemie, Trenton, New Jersey, have been shown to be effective in reducing material susceptibility to hydrolysis. Still other hydrolytic stabilizers, such as those based on carbodiimide or polycarbodiimide or based on epoxidized soybean oil, are considered useful. The total amount of hydrolytic stabilizer used is usually less than 5.0% by weight of the total composition.

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In addition to hydrolytic stabilizers, various plasticizers are usually added to increase the flexibility and durability of the final product, as well as to facilitate the processing of the material from the resin form into a membrane or sheet. For example, but without the intention of limiting, plasticizers which are based on butyl benzoylphthalate are particularly useful. Regardless of the type of plasticizer or mixture of plasticizers used, if used, their total amount is usually less than 40.0% by weight of the total composition.

The polyurethane-based polyurethanes of the present invention may also contain fillers, especially when single layers are produced where hydrogen bonding between layers is not critical. The class of materials typically referred to as fillers include porous and granular materials, non-polar polymeric materials, and inorganic anti-caking agents. Examples of such materials include, but are not limited to, glass and carbon fibers, glass flakes, silica, calcium carbonate, clay, mica, talc, carbon black, granular graphite and metal flakes. Typically, when fillers are used, their total amount is less than 60.0% by weight of the total weight of the composition.

Still another class of ingredients that can be used in the polyol polyester urethane compositions of the invention are flame retardants. Although the amount of retardant used generally depends on the intended use of the final product, the total amount of these agents considered regardless of the application is 40.0% or less based on the total weight of the total composition. Of the various flame retardants considered particularly useful are those based on antimony oxide compositions and phosphates or halogenated compounds.

Regarding the use of auxiliaries, otherwise known as processing aids, small amounts of antioxidants, UV stabilizers, thermal and light stabilizers, organic anti-caking agents, dyes, fungicides, demoulding agents and lubricants can be used, with the total content of all these auxiliaries in processing is usually less than 3.0% by weight.

It may also be expedient to add a catalyst to the reaction mixture for preparing the membrane composition of the invention. Any catalyst commonly used in this field may be used for this purpose to catalyze the reaction of the isocyanate with a compound containing reactive hydrogen atoms; see, e.g., Saunders et al., Polyurethanes, Chemistry and Technology, Part I, Interscience, New York, pp. 228-232; see also Britain et al. J. Applied Polymer Science, 4, 207-211, 1960. Such catalysts include salts of organic and inorganic acids, and organometallic derivatives of bismuth, lead, tin, iron, antimony, uranium, cadmium, cobalt, thorium, aluminum, mercury, zinc, nickel, cerium , molybdenum, vanadium, copper, manganese and zirconium, as well as phosphines and tertiary organic amines. Examples of organotin catalysts are stannous octoate, stannous oleate, dibutyltin dioctoate, dibutyltin dilaurate, etc. Examples of tertiary organic amines are triethylamine, triethylenediamine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetraethylethylenediamine, N-methylmorpholine, N-methylmorpholine, N, N, N ', N' -tetramethylguanidine and N, N, N ', N'-tetramethyl-1,3-butanediamine.

Regardless of the catalyst (s) used (if used), the amount of these materials is usually less than half a percent by weight (0.5% by weight) based on the total weight of the polyester polyol based thermoplastic urethane mixture.

Among the extenders which are optionally but preferably used are alcohols and amines. For example, alcohol-based extenders may include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and the like; and dihydroxyalkyl aromatic compounds such as bis (2-hydroxyethyl) hydroquinone ethers and resorcinol; a, a'-diol of p-xylene, bis (2-hydroxyethyl) ether a, a'-diol of p-xylene; a, a'-diol of m-xylene and its bis (2-hydroxyethyl) ether and mixtures thereof. Examples of amine extenders are aromatic diamines such as p-phenylenediamine, m-phenylenediamine, benzidine, 4,4'-methylenedianiline, 4,4'-methylene bis (2-chloro

187 071 roaniline) and the like. Examples of amino alcohols are ethanolamine, propanolamine, butanolamine etc.

Preferred extenders include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol and the like.

In addition to the extensions described above, a small amount of tri-functional extenders such as trimethylolpropane, 1,2,6-hexanetriol and glycerin may also be present. The amount of trifunctional extender used is preferably 5.0% or less equivalent, based on the total weight of the reaction product and the active hydrogen containing groups used.

In general, the ratio of polyol polyester to extension can vary within a relatively wide range, depending primarily on the desired hardness of the final polyurethane elastomer. Thus, the equivalent ratio of polyol polyester to extender should range from 1: 0 to 1:12, and more preferably from 1: 1 to 1: 8.

In addition to at least one polyol-based urethane, layer 30A of Figure 24 may include one of the following, and layer 30 of Figures 4 and 5 preferably also contain one or more materials selected from the group consisting of ethylene vinyl alcohol copolymers, polyvinylidene chloride, copolymers of acrylonitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, crystalline polymers and thermoplastic structural polyurethanes. Such materials are preferably mixed with a polyester polyol urethane component prior to forming the membrane, using traditional mixing techniques.

With respect to single-layer bodies 30A, it is preferred that the total amount of one or more of the above-mentioned materials is up to 30.0% by weight, since for larger quantities the resulting product is somewhat inflexible. However, in the case of multilayer moldings, the total amount of one or more of the above-mentioned materials in a given layer mix may be up to about 95.0% by weight. Therefore, for multilayer structures, layer 30, preferably comprising blends of at least one polyester polyol urethane and one or more of the above materials will generally contain up to 70.0% of a polyester polyol thermoplastic urethane, but will more preferably contain between about 1.0% to about 50.0% by weight of thermoplastic urethanes based on polyol polyols. In particularly preferred shaped bodies, the content of the thermoplastic polyester polyurethane urethane in the layer 30 is in the range between about 5.0% to about 25.0% by weight.

Of the various materials considered to be useful in blends with polyol polyester urethanes, ethylene vinyl alcohol copolymers and materials containing ethylene vinyl alcohol copolymer mixtures are generally preferred.

Commercially available products based on ethylene vinyl alcohol copolymers such as SOARNOL have proved effective⁰, from Nippon Gohsei Co., Ltd. (UAS) from New York, NY or EVAL °, from the Eval Company of America, Lisie, Illinois. The average ethylene content of particularly preferred commercially available ethylene vinyl alcohol copolymers such as EVAL ° LCF101A is generally between about 25 mol% and about 48 mol%.

Other materials suitable for use in the mixtures described above with one or more urethane based on polyester polyol, commercially available include BAREX ° 210, a copolymer of acrylonitrile and methyl acrylate, from British Petroleum Co. and ISOPLAST⁰, a thermoplastic structural polyurethane, from Dow Chemical Co.

In addition to mixing the materials selected from the group described above consisting of copolymers of ethylene and vinyl alcohol, polyvinylidene chloride, copolymers of acrylic nitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, crystalline polymers and thermoplastic structural polyurethanes with polyurethane-based materials these can be used to produce separate layers for lamination in multi-layer fittings.

Although generally recommended. that polyurethanes used in both single-layer and multi-layer fittings are based on aromatic isocyanates, such

187 071 like diphenylmethylene diisocyanate (MDI), in some multilayer structures it may be desirable to use aliphatic polyurethanes in combination with the barrier materials described above. More specifically, polyurethanes based on aliphatic isocyanates are preferred where it is believed that above a certain concentration aromatic isocyanates could react with the barrier material used. For example, when the mixed layer contains copolymers of ethylene and vinyl alcohol in a concentration of 5.0% by weight, polyurethanes based on aliphatic isocyanates are preferred. However, the addition of a relatively small amount of at least one thermoplastic aromatic polyurethane (i.e. obtained from aromatic isocyanates) as viscosity modifiers may also be advantageous. Thus, a preferred mixed layer composition comprising at least 5.0% by weight of at least one copolymer of reactive barrier material, such as a copolymer of ethylene and vinyl alcohol, can be defined as comprising: (a) at least 50% by weight of at least one barrier material selected from the group consisting of ethylene vinyl alcohol copolymers, polyvinylidene chloride, copolymers of acrylonitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, crystalline polymers and ternoplastic polyurethanes; (b) 1% by weight to 5.0% by weight of at least one thermoplastic aliphatic urethane; and (c) up to about 3.0% by weight of thermoplastic aromatic urethanes, wherein the total blend constitutes 100% by weight. Typically, thermoplastic aromatic urethanes are also selected from the group consisting of materials based on polyesters, polyethers, polycaprolactone, polyoxypropylene and glycol and high molecular weight polycarbonates and mixtures thereof.

In addition, it may be desirable in some applications to include polyurethane blends to form layers 30A and 30, especially considering hydrolysis susceptibility. For example, a polyurethane containing soft segments of polyol polyethers or polyol polyesters obtained from a carboxylic acid and diol reaction mixture in which reaction units of the reaction product have more than eight carbon atoms can be mixed with polyurethanes containing polyol polyesters having eight or fewer atoms coal. Preferably, polyurethanes other than those containing polyol polyester repeat units having eight carbon atoms or less will be present in the blends in an amount not exceeding about 30% by weight (i.e., 70.0% by weight of urethane based on ethylene glycol polyadipate, 30.0 % urethane based on polyol polyisophthalate). Specific examples of polyol polyesters in which the reaction product has more than eight carbon atoms include poly (ethylene glycol isophthalate), poly (1,4-butanediol isophthalate) and poly (1,6-hexanediol isophthalate).

In addition, instead of using mixtures of different thermoplastic urethanes, it is also possible to use a single polyurethane in which various soft segments are embedded. Again, without being intended to be limiting, these soft segments may include, in addition to soft segments having a total of eight or fewer carbon atoms, polyether polyethers, polyol polyesters having a total of more than eight carbon atoms, or mixtures thereof. It is believed that the total amount of soft segment components, including the carboxylic acid and diol reaction product, having a total number of carbon atoms above eight, can be present in an amount of up to about 30% by weight of the total weight of the soft segments contained in this polyurethane. Thus, at least 70.0% by weight of the soft segment repeating units will be carboxylic acid and diol products for which the total number of carbon atoms in this reaction product is eight or less.

It should also be noted that there are many ways to add polyurethanes with up to 30% by weight polyesters having repeat units containing more than eight carbon atoms to the polyurethanes of the invention. 30% or less of polyurethane obtained from polyol polyesters containing repeating units having more than eight carbon atoms may be mixed in the form of a finished polymer with 70% by weight or more of polyurethanes obtained from polyol polyesters containing repeating units having eight or fewer carbon atoms, or one polyurethane can be made from a mixture of polyol polyesters in which 70% or more by weight contains repeat units with eight or fewer carbon atoms, while the difference includes units

187 071 repeatable with more than eight carbon atoms, as previously described. The polyurethane can be prepared from one polyol obtained by the reaction of dicarboxylic acids and diols so that 70% by weight of the polyol polyester repeat units contain eight carbon atoms or less. Combinations of these methods are also possible. Among the acids with more than six carbon atoms that can be used are isophthalic and phthalic acids.

As mentioned, the membranes 28 of the invention may also be in the form of multilayer structures. For example, the membranes 20 and 28A of Figs. 4-7 include a layer 32 formed of a flexible, elastic elastomer that is preferably resistant to expansion over a predetermined maximum volume when the membrane is exposed to gas pressure.

Layer 32 is preferably formed of a material or combination of materials that provides excellent thermal welding capability, flexural fatigue strength, appropriate modulus of elasticity, tensile and tear strength and abrasion resistance. It was found that among the available materials corresponding to this characteristic, thermoplastic elastomers from the urethane family, otherwise referred to as thermoplastic urethanes or simply TPU, are strongly recommended due to their excellent processability.

Among the numerous thermoplastic urethanes useful in forming the outer layer 32, urethanes such as PELLETHANE proved to be particularly useful⁰ 2355-ATP, 2355-95AE and 2355-85A (registered trademarks of Dow Chemical Company of Midland, Michigan), ELASTOLLAN0 (registered trademark of BASF Corporation) and ESTANE0 (registered trademark of BFGoodrich Co.), all of which are either based on esters or ethers. It is also possible to use other thermoplastic urethanes based on polyesters, polyethers, polycaprolactone and high molecular weight polycarbonates of glycols. In addition, it should also be noted that in addition to commercially available polyurethanes, layer 32 of Figure 4 and layers 32 and 34 of membrane 28a shown in Figure 7 can also be made of polyurethanes based on polyol polyesters containing soft segments in which the reaction product has eight or fewer carbon atoms. Typically, this resulted in a reduction in GTR, because much of the gas diffusion resistance in the multilayer structure is derived from the barrier layer.

As previously mentioned, the membranes described in the present invention can be formed by various processing techniques, including, but not limited to, extrusion, blow molding, injection molding, vacuum molding, thermal welding or high frequency welding of pipes and sheets of compressed film materials. With respect to the multilayer membranes described in the present invention, they can be made of films formed by coextrusion of the materials forming the layer 30 together with the material forming the layer 32. After the formation of the multilayer film, the materials forming this film are heat-welded or by high frequency current creating fill gas with highly elastic membranes.

These membranes, whether in the form of a sheet, a permanently closed container, cushioning pads, shock absorbers or other structures, will preferably have a tensile strength of at least about 17.25 MPa, a module of 100% stretch between about 2.4-20.7 MPa and / or elongation at break from at least about 250% to about 700%.

Figures 6 and 7 show an alternative membrane body 28A in the form of an elongated, multilayer tube-shaped portion. This modified membrane 28A is essentially the same as the membrane 28 shown in Figs. 4 and 5, except that the third layer 34 adheres to the inner surface of the layer 30, so that the layer 30 lies between the outer layer 32 and extremely inner layer 34. It is preferred that this extremely inner layer 34 is also made of thermoplastic urethane material. In addition to the expected benefit of better protecting layer 30 against degradation, layer 34 promotes high quality welds, which

187 071 makes it easy to give three-dimensional shapes to products such as cushioning inserts used in footwear.

Membranes such as those shown in Figs. 1-7 and 24 are preferably made of extruded tubes. The lengths of these tubes usually range from about 30 cm to about 150 cm. These membranes can then be inflated to the desired initial pressure ranging from 7 kPa overpressure to 700 kPa, preferably in the range from 35 to 350 kPa, it being preferred that the closed gas is nitrogen. The pipe sections are then welded thermally or by high frequency current to the desired length. Individual membranes, produced by thermal welding or by high frequency current, are then separated by cutting along the welded surfaces between adjacent membranes. It should also be noted that membranes can be made of so-called '. flat extruded pipes.

Regarding the extrusion of the multilayer moldings described herein, as the material forming layers 30, 32 and possibly layer 34 moves towards the extruder outlet in separate flow channels, as soon as it reaches the mouthpiece outlet, the alloy streams are combined and flow together, entering the extruder head in layers characteristic of laminam flow. For optimum wetting for maximum adhesion between adjacent parts of layers 30, 32 and 34, respectively, and as a result of increasing the amount of hydrogen bonds between those layers in which the material used promotes the formation of hydrogen bonds, it is preferable that the materials be joined at a temperature between about 140 ° C and about 240 ° C, at a pressure of at least about 1.4 MPa. For multilayer laminates, it is preferable that the polyol polyesters used in the polyurethanes of layers 30, 32 and 34 have a significant proportion of aliphatic compounds because it is hardened that aliphatic urethanes can easily be processed by traditional techniques such as plate extrusion.

It is believed that the bonds of the water-bond occur between the respective layers as a result of the availability of functional groups with hydrogen atoms that can participate in the hydrogen bond, such as hydrogen atoms in hydroxyl groups or hydrogen atoms associated with nitrogen atoms in hydroxyl groups, and various acceptor groups, for example such as oxygen atoms in hydroxyl groups, oxygen atoms of carbonyl groups in urethanes and ester groups, and chlorine atoms in PvDc.

The following reaction illustrates the theoretical surface bonding considered to occur between layers 32 and 34 with the membrane layer 30 over the entire contact surface:

<img file="PL187071B1_D0001.tif" />

<img file="PL187071B1_D0002.tif" />

_ &lt;CHCHI - (CHC Η I_

2 n 2 _ (CHCH) - IC H, CH) _ ¹ 2 2 ni

AND

OH

AND

Γ ¹¹ _ | _N HCO - &lt;

ABOUT

II

R-NHCO _R'-OC

187 071 where R is an aromatic group: -C6H4-, -CH2-C6H4a R 'is a short chain of diol, such as (CH2) 4

It is believed that in addition to the hydrogen bonds described above, a certain amount of covalent bonds, to a more limited extent, is formed between the second and third layers, 32 and 34, respectively, with the first layer 30. It is also believed that the interaction force between adjacent thermoplastic urethane layers and the main layer is influenced by other factors, such as directional and inductive forces, otherwise known as van der Waals forces, resulting from London interactions occurring between any two molecules and dipole interactions. dipole that occur between polar molecules.

The hydrogen bond described above, in contrast to earlier solutions of shaped bodies, in which due to disregarding the existence and / or strength of such bond, in order to obtain bond between different layers, generally required the use of adhesive layers, such as Bynel⁰.

As mentioned above, although the share of fillers in single-layer fittings up to 60% by weight is allowed, their share in the processing of multi-layer membranes in which hydrogen bonds are desired should be limited, or should not be used at all, because fillers have a negative effect on the so-called the ability to form hydrogen bonds in multi-layer fittings.

Figures 12-16 show membranes in the form of air-filled blisters produced by blow molding. In order to form these bubbles, single-layer preforms are extruded or those formed of two- or three-layer films are coextruded as shown in Figs. 21-23. The preforms are then blown and molded using traditional blow molding techniques. The resulting blisters, examples of which are shown in Fig. 12 and 15, are filled with the desired gas to the selected initial pressure, after which the inlet gap, e.g. the inlet gap 38 is closed by welding with high frequency current.

Still other fittings formed from the membranes described are shown in Figs. 8-10. The films or sheets or extruded single-layer films or co-extruded double-layer or three-layer films are given the desired thickness. For example, the thickness range of coextruded sheets or films is preferably between 0.0127 mm and 0.25 mm for layer 30 and between 0.1 mm and about 2.5 mm for layers 32 and 34, respectively. Generally, in the case of single-layer cushioning moldings, the average layer thickness is between 0.13 mm and about 0.15 mm, and more preferably between about 0.5 mm and about 1.02 mm.

Still another formed from the membrane of the invention is shown in Figs. 17 and 18. The bladder was formed by forming a single-layer or co-extruded multi-layer tube of the desired thickness range. The tube is flattened and the opposite walls are welded at selected points and at each end, by traditional techniques: thermal welding or using high frequency current. The cushioning pad was then filled with gas through the formed mouthpiece 38 to the desired pressure, which ranges from 7 kPa overpressure to 700 kPa, preferably 35 to 350 kPa, the trapped gas being nitrogen.

In addition to the use of the membranes of the invention as the above-described cushion pads or inner tubes, another preferred use of the membranes of the invention is the shock absorbers shown in Figures 19, 20 and 25.

Fig. 25 shows a shock absorber formed from the single-layer membrane described above. Similarly, in Figures 19 and 20 two alternative shock absorber shapes formed from the multilayer membrane according to the invention are shown. Shock absorbers, or more precisely hydraulic shock absorbers, are used in vehicle suspension systems, vehicle braking systems, industrial hydraulic shock absorbers or in applications where there is a pressure difference between two potentially different liquid media. The membrane 124 divides the hydraulic shock absorber into two compartments or chambers, one of which contains gas such as nitrogen and the other containing liquid. Membrane 124 has

187 071 the annular collar 126 and the flexible body 128. The annular collar 126 is adapted to be attached over its entire circumference to the inner surface of the spherical battery, such that the body 128 divides the shock absorber into two separate chambers. The flexible body 128 slides substantially diagonally inside the spherical shock absorber, and its position at a given moment depends on the gas pressure on one side in relation to the liquid pressure on the other side.

As another example, Fig. 20 shows an article in the form of a hydraulic shock absorber whose first layer 114 is made of the materials described above in connection with layers 30A and 30. In addition, the article has layers 112 and 116 formed of one or more thermoplastic urethanes and barrier material described above in connection with layers 32 and 34. As can be seen, the first layer 114 extends only along a portion of the entire shock absorber body. The use of such moldings, otherwise known as discontinuous structures, may be desirable in conditions where the possibility of delamination along certain segments of the product is greatest. One such location is along the annular collar 126 of the multi-layer bladder body or hydraulic shock absorber diaphragm. Thus, while the multilayer membranes of the invention are generally more resistant to delamination and better perform the role of preventing gas leakage due to capillary action along boundaries between layers, such as those occurring along the annular flange, it should be noted that the membranes 110 described in the present invention may contain segments not containing layer 114.

For the production of membranes 110, which in turn are formed into the products shown in Fig. 19, 20 and 25, a variety of processes may be used including, but not limited to, extrusion, coextrusion, continuous extrusion blow molding, batch extrusion using (1) reciprocating screw systems; (2) battery-type slider systems; and (3) battery-type head systems, co-injection elastic blow molding, extruded or co-extruded sheets, blown film, pipes or profiles. In relation to multilayer processes, it was found that using coextrusion and conductive materials, products having the aforementioned hydrogen bond between the respective layers 114 and 112 and 116, respectively, are obtained. To form a product such as a hydraulic damper bladder or diaphragm using a multi-layer process such as blow molding, any of the commercially available machines, such as Bekum BM502, with a coextrusion head model No. BKB95-3B1 (not shown) can be used or Krup model KEB-5, with coextrusion head model No. VW60 / 35 (not shown).

As noted previously, the production of single-layer membranes generally resembles the production of multi-layer membranes, but requires much less process control elements, for example, single-layer membranes only require a single extruder without a feed block. Sheets can be made by forcing the molten polymer formed in the extruder through a flat die. Flattened pipes and fittings used in blow molding are produced by forcing the molten polymer formed in the extruder through an annular die.

The following is a brief description of the preferred multilayer processing techniques. Initially, the resinous extrusion materials are dried according to the manufacturer's specifications (as needed) and fed to the extruder. In general, the materials are fed into the extruder in the order in which the layers are to be arranged. For example, in the case of a three-layer molding, material containing a polyol-urethane is fed into an external extruder, material such as TPU and / or one or more barrier material is fed into the middle extruder, and material such as TPU is fed to the internal extruder. The extruder thermal profile is selected to ensure the best processing of individual materials. Preferably, the temperature difference at the outlet of each extruder should not exceed -6 ° C. As the material is moved in each extruder, the heat profile is selected to obtain the best molten mass. Generally, the heat profile is selected between 145 ° C to about 240 ° C, with the feed zone having the lowest setting, and all other settings increase gradually by approximately

187 071 dosing has the lowest setting, and all other settings increase in steps of approximately 5 ° C until the desired alloy is obtained. After leaving the extruder, the material is directed, sometimes through a pipe section, to a multi-layer head (i.e. three or more heads). This is the point where any temperature difference adjustments can be made. The pumping action of the extruders not only directs the material to the channels of individual heads or to the flow paths, but also determines the thickness of each layer. For example, if the first extruder has a diameter of 60 mm, the second extruder has a diameter of 35 mm and the third extruder has a diameter of 35 mm, the time needed to produce a 1.3 liter bladder or diaphragm, requiring 2 mm for the outer layer, 0.8 mm for the middle layer and 2 mm for the inner layer for various extruders it will be about 26 seconds for the first extruder at a screw rotation speed of about 10 rpm, the screw rotation speed of the second extruder is about 5 rpm and the third is about 30 rpm. When the material enters the head channels or flow paths, its temperature is generally kept constant or lowered to take into account the thermal strength of the alloy. Individual head channels or flow paths keep melted masses separately, directing them downwards and shaping them pre-blow.

Just before entering the lower nozzle or sleeve and the lower drum, the head channels or flow paths connect with each other under pressure created as a result of the creation of one common surface now the flow path, the gap between the lower sleeve and the drum and the pressure exerted on individual layers by appropriate extruders . This pressure must be at least 1.38 kPa, and generally, under the conditions described, exceeds 5.52 kPa. In the place where the materials come together, one molded material is prepared for blowing, which is a laminate composed of three layers. The upper pressure limit is generally limited only by the physical strength of the head. After leaving the head, the laminate is closed at each end by two halves of the mold and gas, such as air, is blown into the mold, causing the laminated mold to expand to the dimensions of the mold. This continues until it cools down (i.e. in the case of the sample mentioned above about 16 seconds), after which the gas is discharged from the mold. The shaped body is then removed from the mold and allowed to cool to allow cutting off the seams or further processing required for some parts. It should be obvious to those skilled in the art that, before being fully melted and pre-formed into a tube, the layers must be separated from each other until they are bound together under the influence of temperature and pressure.

Experts in the plastics processing industry know that the three essential parts of a blow molding machine, namely extruders, nozzle heads and closed molds, come in a variety of sizes and solutions to meet customer demand for size and production schedule.

Another useful technique for forming membranes according to the invention is a process called sheet coextrusion. Coextrusion of sheets essentially involves the simultaneous extrusion of two or more polymeric materials through a single die, where the materials combine to form separate, well-bonded layers, resulting in one extruded article.

The equipment needed to produce coextruded sheets consists of one extruder for each type of resin, which are connected to the coextrusion feeder block as shown in Figures 21 and 23, and are available from many companies, including Cloreon Company of Orange, Texas and Production Components, Inc. from Eau Claire, Wisconsin.

The coextrusion feeder block 150 consists of three sections. The first section 152 is the feed input section, connecting individual extruders and individual resin streams (round section) with the programming section 154. Next, the programming section 154 gives each resin stream a rectangular section with dimensions corresponding to the desired thickness of the individual layers. Transition section 156 combines separate single layers with a rectangular cross-section in one square-channel. The melt temperature of each TPU layer should generally be between 145 ° C and 240 ° C. In order to optimize the adhesion between adjacent layers, the actual temperature of each melt stream should be selected so that the viscosities of these streams are similar. Connected

187 071 laminame melt streams are then formed into one rectangular cross-section extruded stream in a flat nozzle 158, which is preferably in the form of a coat hanger, as shown in Fig. 22, currently widely used in the plastics industry. The extrusion is then cooled by means of drums to form a rigid sheet either by casting or calendering.

As with sheet extrusion, the equipment necessary for making coextruded pipes consists of one extruder for each type of resin, each of these extruders connected to a branched tubular nozzle. The alloy from each extruder enters a multi-hole nozzle, such as that shown in Figure 23, commercially available from many different sources, such as, for example, Canterberry Engineering, Inc. from Atlanta, Georgia and Genca Corporation of Clearwater, Florida, and flows through separate circular channels 172A and 172B for each alloy. The flow channels then take the shape of circular rings, the size of which is proportional to the desired thickness of each layer. The individual alloys are then combined to form one common melt stream just before nozzle inlet 174. The alloy then flows through a channel 176 formed by a ring between the outer surface 178 of the cylindrical stem 180 and the inner surface 182 of the cylindrical nozzle body 184. Then, the rut-shaped extrudate leaves the nozzle and is cooled in this form by means of various traditional methods of pipe calibration and pipe fittings. Although in fig. 23 a two-component pipe is shown, it is understood by those skilled in the art that additional layers can be introduced using separate flow channels.

Regardless of the processing used, it is desirable for the resulting alloy of materials to be homogeneous to achieve bonding between layers over the intended length or section of the laminated article. Therefore, the multilayer processes used should be carried out at a controlled temperature from about 145 ° C to about 240 ° C. In addition, it is important to maintain an appropriate pressure of at least 1.4 kPa at the point where the layers join and where the hydrogen bond described above is to be formed.

As previously emphasized, in addition to the excellent bonding that can be achieved with the laminated membrane moldings of the invention, another purpose, especially for membranes used as shoe cushioning inserts, is to provide membranes that are able to retain entrapped gas for a longer period of time. In general, membranes that provide a gas permeation rate of 15.0 or less, measured in accordance with ASTM D-1434-82, for membranes with an average thickness of 0.05 mm, are suitable for long-term applications. Thus, although the membranes according to the invention may have varying thicknesses, depending mainly on the intended use of the final product, the membranes according to the invention will have a gas permeation value of 15.0 or less when normalized to a thickness of 0.05 mm, regardless of the actual thickness membrane. Similarly, although nitrogen is the preferred gas trapped for many fittings and serves as a comparative factor in the analysis of gas permeation rates according to ASTM D-1434-82, membranes may contain a variety of different gases and / or liquids.

Therefore, due to the excellent properties of urethanes based on polyol polyesters in terms of flexibility, resistance to moisture degradation and resistance to undesirable gas permeability, the membranes of the invention can be used, among others, as single-layer or multi-layer fittings. For preferred fittings, the membranes of the invention have a gas transmission rate of 10.0, and even more preferably have a gas transmission rate of 7.5 or less, for nitrogen, with a layer thickness of 0.05 mm. Even more preferably, the membranes of the invention have a gas passage rate of 5.0 or less, and even more preferably, a gas passage rate of 2.5 or less for nitrogen at 0.05 mm thick. For the most preferred fittings, the membranes of the invention have a gas passage rate of 2.0 or less for nitrogen, for membranes with an average thickness of 0.05 mm.

To prepare samples 1-12 as described in Table I for the analysis of the gas permeation rate; a polyol based urethane was prepared by adding to a 2000 mL reaction flask one or more of the following: (1) a polyol polyester (e.g. a commercial product, or a dicarboxylic acid and diol reaction product as described above); (2) a dual-function extension cord; and (3) auxiliary agents such as waxes and antioxidants. The hydroxyl component was then heated to a temperature between about 95 ° C-115 ° C (depending on composition) and mixed to dissolve and homogenize the ingredients. In turn, the pressure was lowered below 0.2 mi under constant stirring to control foaming of the mixture. After foaming, the flask was degassed for about 30 minutes until bubble formation ceased completely.

The isocyanate component was then prepared by placing the diisocyanate in a 250 ml polypropylene beaker and placing it in a heater at a temperature between 50-65 ° C. When the temperature reached 50-65 ° C, the desired amount of the isocyanate component was weighed and, if necessary, the catalyst was added with continuous stirring.

To obtain polymerization, after complete mixing of the catalyst, the desired amount of hydroxyl component was added to the isocyanate component. When the polymerization began and the viscosity increased (usually between about 7-12 seconds after the addition), the reaction product was poured onto plates, coated with a suitable release agent and set aside to cool completely. After cooling, the freshly formed polymer was cut into granules and dried for about 2-4 hours at a temperature between 85 and 100 ° C. Then, for analysis of gas permeability, samples 1-10 were prepared, as shown in Table I, by pressing molten plastic granules into sheets.

Regarding sample 11, as shown in Table I, after preparing the polyol based urethane as described above, 70.0% by weight of the material was mixed and extruded together with 30.0% by weight BARJEX ° 210, supplied by BP Chemical, Inc., at about 215 ° C to prepare a mixed sample for gas permeability analysis. In turn, regarding sample 12, a membrane for gas permeability analysis was prepared by mixing 70.0% by weight of a polyol based urethane prepared in sample 12 with 30.0% by weight BAREX 210 at a temperature of about 215 ° C.

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TABLE I^x

Gas transmission rates for single layers

<img file="PL187071B1_D0003.tif" />

All values ​​given in Table I / are expressed as weight percent.

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1. FOMREZ® 44-56 from the company Witco Chem ^ al

2. FOMREZ® 44-160 from Witco Chemical

3. FOMREZ® 22-112 from Witco Chemical

4. FOMREZ® 22-225 from Witco Chemical

5. FOMREZ® 8066-120 - 50 parts 1,6-haksanodiou adipate and 50 parts HD Isophthalate polyol polyester from Witco Chemical

6. UrethHan® 2050 from the CPHall Company

7. DESMODUR W from the company BAYER AG (America)

8. ISONATE® 2125M from DeWcChemica Co.

9. A mixture of 80 parts ISONATE⁰ 2125 and 20 parts ISONATE® 2143 from Dow Chemical Co.

10. IRGANOX® 1010 from Ciba-Geigy Chemical Co.

11. ADVAWAX® 280 from Morton Plastics, Inc.

12. Mixture of 50 parts stannous octoate and 50 parts dioctyl phthalate

13. Montana wax ester

14. Kamamidy W-40 (ethylene bis stearamidewy wax) from Witco Chemical

15. PELLETHANE0 2355-85 ATP from Dow Chem ^ al Co.

16. Pellethane⁵ 2355-95 AE from Dow Chemical Co.

Table II

<td>Sample No.</td><td>Average thickness</td><td>GTR (cm³/ m²* atm * Zzień)</td><td>GTR (Cm3 / m² * atm * day) normalized to a thickness of 0.5 mm</td>

<td> 1</td><td>0.413 mm</td><td> 30,95</td><td> 25,15</td>

<td> 2</td><td>0.386 mm</td><td> 11,71</td><td> 8,9</td>

<td> 3</td><td>0,435mm</td><td> 9,13</td><td> 7,82</td>

<td> 4</td><td>0,493mm</td><td> 6,58</td><td> 6,08</td>

<td> 5</td><td>0.446 mm</td><td> 7,07</td><td> 6,19</td>

<td> 6</td><td>0.506 mm</td><td> 9,22</td><td> 9,19</td>

<td> 7</td><td>0.506 mm</td><td> 6,19</td><td> 6,17</td>

<td> 8</td><td>0.465 mm</td><td> 1,20</td><td> 1,10</td>

<td> 9</td><td>0.438 mm</td><td> 3,47</td><td> 2,93</td>

<td> 10</td><td>0.367 mm</td><td> 17,92</td><td> 12,96</td>

<td> 11</td><td>0.488 mm</td><td> 1,24</td><td> 1,19</td>

<td> 12</td><td>0.434 mm</td><td> 2,73</td><td> 2,33</td>

<td> 13</td><td>0.507 mm</td><td> 36,42</td><td> 36,33</td>

<td> 14</td><td>0.464 mm</td><td> 24,12</td><td> 22,01</td>

As shown in Table II, each of Samples 2-12 showed a higher gas permeability rate than Control Samples 13-14, which were prepared from commercially available thermoplastic methane resins. Each of the samples, namely samples 2-10, relating to urethanes based on ooliaZinate ethylene glycol and ethylene glycol and samples 11-12, referring to mixtures of urethanes based on ooliaZeethylene glycolate, together with BAREX ° 20, generally showed better values ​​of gas permeation rate than polyurethane based urethane b ^ a ^ dio ^ from sample 1. As you can see,

187 071 each of samples 2-12 had a gas flow rate below 15.0 for N2 at a thickness of 0.5 mm.

A multilayer sample was also prepared by laminating a polyol urethane based on sample 11 of Table I, with a third layer of commercially available material known as ISOPLAST®. When laminating the multilayer sample, a 0.13 mm thick ISOPLAST film was placed⁵ between two layers of polyol based urethane, 0.48 mm thick each. Then the multilayer sample was compressed using a hydraulic press whose upper and lower plate were heated to a temperature of about 215 ° C. The films were pressed together under a pressure of about 13.8 MPa, obtaining a sample with a total thickness of about 0.464 mm.

After analyzing the gas transmission rate on a multilayer sample, it was found that this sample had a GTR of 8.87 for nitrogen at a thickness of 0.464 mm, and after normalization to 0.5 mm had a GTR of 8.09. Thus, this multilayer sample also achieved an assumed gas transmission rate of less than 15.0.

Finally, in addition to the monolayer and multilayer membrane samples discussed above, a gas-permeable, thermally cross-linked version of a urethane based on a polyol polyester was prepared and analyzed.

This sample, as shown below in Table III, was prepared by dehydrating and degassing the polyol polyester under vacuum for two hours at 100 ° C and cooling to 60 ° C, after which catalyst was added. Simultaneously, Isonate® 2143L was heated to 45 ° C and degassed for 20 minutes before being added to the polyester component. The polyol polyester and polyisocyanate were then mixed and carefully mixed in a polypropylene beaker to avoid air introduction. After mixing, the mixture was poured into a warm, flat mold, where it was allowed to react for two hours at ambient temperature and atmospheric pressure before removing the sample from the mold. Before testing, the resulting membrane was left under ambient conditions for seven days.

Table 111

<td>Ethylene glycol adipate (a) 1000 MW^{1 2 3}</td><td> 77,36</td>

<td>MDI2</td><td> 22,34</td>

<td>Catalyst</td><td> 0,30</td>

<td></td><td> 100,0</td>

1. FOMREZ ™ 22-225 supplied by Witco Chemical

2. ISONATE ™ 2143L, a liquid MDI supplied by Dow Chemical Co. from Midland, MI

3. COCURE ™ 55, supplied by Caschem Inc., from BAyonne, NJ

The thermosetting urethane version based on polyol polyols, shown in Table III, showed a gas transmission rate of 3.07 for a thickness of 1.85 mm. After normalization, the gas transmission rate was calculated to be 11.2 for nitrogen at a layer thickness of 0.5 mm. Thus, both thermoplastic and thermally crosslinked material have proved useful.

In addition to the better gas permeability provided by the various molded articles of the polyol polyester urethanes described herein, the articles made of polyol polyester urethanes also showed a significant improvement in durability compared to thermoplastic urethanes containing no polyol polyesters.

For example, as shown in Table IV below, samples were prepared and analyzed for stability using a test method known as the KIM test. In accordance with the KIM test procedure, two sheets of different materials were extruded, each sheet formed into identical shape cushioning pads with an average wall thickness of 0.457 mm. The material used for the A cushioning insert is the same as composition No. 11 shown in Table I. B cushioning pads are made of a material such as Pellethane 2355-85A,

187 071 thermoplastic urethane, not containing any soft segments of ethylene glycol polyadipate.

After inflation of the cushioning pads with nitrogen to 138 kPa, each sample was compressed periodically with a piston with a pressure plate of 4.0 inches, reciprocating. The stroke of each piston was calibrated to correspond to a height that compresses each sample to an average of 25% of the initial height at maximum stroke. The pistons then operated until part damage was found. Part damage, as used herein, is defined as sufficient nitrogen leakage and deformation of the cushion insert, causing the lever located in identical locations of each cushion insert to contact the microswitch, causing the reciprocating stop of the piston. At this point, the total number of cycles is recorded for each sample, with more cycles representing a more durable material. Preferably, for use as footwear components, permanently inflated cushion pads should be able to withstand at least about 200,000 cycles.

As can be seen from Table IV, type A cushioning pads made of polyol based urethane are more than three times higher than the cushioning pads formed from type B aromatic thermoplastic urethane. Thus, the polyurethane-based urethanes according to the invention not only provide better resistance to undesirable gas flow, but also have been shown to provide greater durability compared to thermoplastic urethanes that do not contain the soft polyester polyol segments in which the repeat units have eight or less carbon atoms.

Table IV

<td>Sample No.</td><td>Average number of cycles</td>

<td>AND*</td><td> 754111</td>

<td>B</td><td> 217797</td>

<td>* Average of 9 tests</td><td></td>

<td>** Average of 10 tests</td><td></td>

In addition to a high degree of durability, it is often desirable to produce products with relatively high transparency, i.e. products that meet certain criteria regarding the level of yellow color and light transmission through the material. For example, product transparency is often taken into account for shock absorbers, such as those used in footwear in which the cushion insert is visible.

In this regard, cushioning pads made of Pellethane 2355-87 ATP, an aromatic thermoplastic urethane, have proved useful as footwear components, since this material has been found to provide acceptable values ​​both in terms of the level of yellow found and the transmission of light through the material. Thus, polyester polyol urethanes preferably have similar, and even more preferably, better transparency characteristics compared to aromatic thermoplastic urethanes, such as Pellethane 2355-87ATP, among others.

Samples of both Pellethane 2355-87ATP and urethane based on polyester polyol were prepared, containing: 50.96% by weight FOMREZ 22-122 (1000 MW); 9.11% by weight of 1,4-butanediol; 38.81% by weight ISONATE 2125M, 0.50% by weight lRGANOX 1010; 0.15% by weight ADVAWAX 280; 0.30% by weight montana wax ester; and 0.02% by weight of the catalyst, in the form of smooth-walled, flattened tubes with an average wall thickness of 0.81 mm. Then, using a Hunter Lab Color QUEST® spectrocolorimeter and according to the instructions for use of this instrument, the yellowness index and total light transmission of these samples were determined for each sample.

Readings of the yellowness index, tested in the reflection coefficient window, were normalized in the form {rsin}. Total permeability measurements were also normalized and the results read in a window for measuring permeability, without using glass plates.

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The yellowness index for Pellethane 2355-87ATP was 4.00 and the total light transmission was 90.85% compared to a maximum transmittance of 100%. Polyol-urethane based on polyol had a yellow index of 1.52 and total light transmission of 91.75%. Thus, urethane based on polyester polyol not only proved to be more durable than aromatic thermoplastic urethanes, but also provides more favorable values ​​in terms of both yellowness index and light transmission. The improvement in terms of both lowering the yellowness index and increasing light transmittance should increase the aesthetic value of many end products.

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