Method of producing laminated packaging material, and packaging containers produced from packaging material

The first method for producing a laminated packaging material and a packaging container made of the packaging material. Technical Field The present invention relates to a method for producing a laminated packaging material. The packaging material includes a central interlayer of paper or cardboard and a coating A barrier layer on one side of the center sandwich.

The invention also relates to a laminated packaging material manufactured according to the method and a packaging container manufactured from the laminated packaging material. It is particularly advantageous to provide a packaging laminate in which polyvinyl alcohol (or starch) mixed with nanoparticles is used as a barrier material.

Technical background It is well known that single-use laminated packaging materials for packaging and transporting liquid foods are used in the packaging industry. Generally, this laminated packaging material is made of a strong and foldable central interlayer. The central interlayer can be made of paper or cardboard, for example, in order to obtain good mechanical structural stability. The liquid-tight plastic coating is coated on the two sides of the center interlayer, thereby effectively protecting the center interlayer made of liquid-absorbing fibers from being penetrated by moisture. Usually, these outer layers are made of thermoplastic plastics (preferably polyethylene), which can give the packaging material good heat-sealing properties, so that the packaging material can be transformed into a packaging product with a specified geometric shape.

However, laminated packaging materials composed entirely of paper or cardboard and liquid-tight plastics have poor air-tightness to gases, especially oxygen. In the packaging of many foods, this is a major disadvantage. When in contact with oxygen, the storage life of such foods, such as fruit juices, will be significantly reduced. In order to add a barrier layer that prevents gases, especially oxygen, to the packaging material, a well-known method in the art is to coat the side of the center interlayer facing the inside of the package with a barrier layer that has excellent air-tightness to oxygen. A thin layer, such as aluminum foil or a thin layer of polyvinyl alcohol.

Compared with aluminum foil, polyvinyl alcohol has many desirable properties, so it is best to use it as a barrier material in many cases. Among these properties, what needs to be explained is the excellent strength properties of polyvinyl alcohol, its compatibility with food and its economic value, as well as its excellent oxygen barrier properties. In addition, in some cases, from the perspective of environment and reuse,

00815202.0 The first use of it to replace aluminum foil as a gas barrier material in food packaging is considered a suitable expedient.

Like many other conceivable barrier or viscous polymers such as ethylene glycol, starch, starch derivatives, carboxymethyl cellulose and other cellulose derivatives or mixtures thereof, polyvinyl alcohol is suitable for coating methods Coating, that is, coating is carried out in the form of a suspension or an aqueous solution. When coating, the solution is dispersed into a uniform thin layer on the substrate, and then it is dried. However, we have found that a disadvantage of this method is that, for example, a polyvinyl alcohol with EAA additive, an aqueous polymer suspension or polymer solution coated on the center sandwich of paper or cardboard, will penetrate Into the fluid-absorbent fibers of the center sandwich. In connection with the removal of moisture for drying and possible curing of the coated barrier layer, the center sandwich will also be exposed to the high temperatures used for drying, and therefore, the risk of harmful cracks in the cardboard or paper layer will be due to the difficult-to-adjust moisture content, respectively. And the drying that occurs in this layer increases.

Swedish patent 440519 proposes to include a thickener such as alginate to reduce the penetration of water into the cardboard. In the patent WO097/13639, it is proposed to use PVOH as a barrier material to be coated on a thin polymer layer in order to prevent the formation of cracks and smooth the surface of the cardboard.

One disadvantage of polyvinyl alcohol is that it is very sensitive to humidity and will quickly lose its barrier properties when exposed to a humid environment. This inconvenience can be achieved by combining polyvinyl alcohol with one or more known food-licensed polymers, such as ethylene acrylic acid copolymer (EAA) or styrene-butadiene copolymer, according to patent WO97/22536 Can be ruled out in advance. The combination of these polymers and polyvinyl alcohol advantageously forms a thin layer with good adhesion and good gas barrier properties, especially oxygen barrier properties. Moreover, the excellent gas barrier properties required by polyvinyl alcohol even It can be maintained in a humid environment.

Patent WO97/22536 discloses the following. First, polyvinyl alcohol mixed with EAA-ethylene copolymer or other similar materials is dispersed and coated on a cardboard coated with a polymer beforehand, and then the temperature is 170°C. Drying and curing at high temperature can form a laminated packaging material with very good barrier properties.

Without being limited by any specific theory, it has been suggested that improved oxygen and water barrier properties can be produced by the esterification reaction between PVOH and EAA under the condition of increasing curing temperature, whereby PVOH is hydrophobicized by EAA polymer The chain is cross-linked, so the polymer chain becomes

00815202.0 No.

An integral part of the PV0H structure.

Another disadvantage when using polyvinyl alcohol instead of aluminum foil as a barrier layer is that, for example, when storing photosensitive food, in many cases it is also necessary to incorporate a certain type of light barrier layer into the packaging material. Even paper or The central sandwich of the cardboard does not allow (that is, visible to the naked eye) any light to pass through, but light in the invisible wavelength range can still penetrate into the packaged food from the outside of the packaging container, and from the perspective of storage life, it may still be harmful. The food has a negative impact. The use of aluminum foil in the packaging material Hu has such advantages. The aluminum foil itself constitutes an excellent barrier layer that can block both gas and light. On the other hand, polyvinyl alcohol is good to be completely transparent even in mixtures with hydrophobic polymers such as ethylene acrylic acid copolymer or styrene butadiene copolymer. According to patent W097/22536, adding conventional light-blocking layer additives such as carbon black and titanium dioxide to any plastic layer in the laminated packaging material is feasible in terms of its operation itself, but in terms of aesthetics, it will be effective. The packaging leaves an unattractive appearance.

In laminated packaging materials, for example, including a barrier layer of polyvinyl alcohol that may be combined with another polymer, another inherent disadvantage is that this packaging material cannot be used in the production of packaging that uses aluminum foil as a barrier layer. The same production equipment as the material is used for production, so that the basic investment costs for new production equipment will need to be invested.

As mentioned above, PVOH has environmental benefits as a barrier material. In addition to these synthetic materials, the possibility of using natural and biodegradable polymers (biopolymers), such as starch and starch derivatives, as gas barrier materials has been studied.

It has been known before that starch has certain gas barrier properties when used in relatively thick coatings, for example, with a coating thickness of about 2 Opm to 30 pm. However, such thick coatings of starch materials are not suitable for use in packaging laminates, because they will easily become brittle during processing, such as lamination and when the laminate is folded into packaging. And there is a tendency to crack and break. In addition to the inability to handle flexibly during manufacture and sale, laminates with thick coatings such as starch may also absorb moisture and cause delamination between the starch layer and its adjacent layers.

It is known from patent WO97/16312 that the very thin coating applied on the center sandwich is used at least in combination with an adjacent plastic layer. At this time, the plastic layer has been extruded and coated with a plastic material. The combination of starch barrier layers can provide some gas barrier properties. Two very thin starch layers were respectively coated on the paper with a dry weight of 0.5 g/m and lg/n?

00815202.0 On the opposite side of the center sandwich layer of the first plate, each thin layer extruded and coated with a plastic layer can provide an oxygen barrier of 289 cm7ni every 24 hours under a standard atmospheric pressure. Similarly, the two starch layers are separated by lg/m? and 1.5g/m' respectively, the oxygen barrier that can be provided every 24 hours under a standard atmospheric pressure is the result obtained can be compared with, for example, the gas barrier performance of a 12-gauge oriented PET film In contrast, therefore, it represents a "medium performance barrier" material.

However, the packaging laminate of patent WO97/16312 is only a medium-performance gas barrier material. This means that the material can only be used to package liquid foods with a short refrigeration period. So far, in the prior art, people still do not know how to produce packaging laminates with high performance gas barrier properties from starch or starch derivative barrier materials. Packaging materials with sufficient gas barrier properties that can be used for long-term storage of liquid foods, that is, extended storage life (ESL) when used for refrigeration, or even for aseptic refrigeration, would be highly desirable. The order of magnitude of this ideal high-performance oxygen barrier performance is about 50cm7m of oxygen barrier that can be provided every 24 hours under a standard atmospheric pressure (23°C, 50% relative humidity)²Or higher, for example up to 30 cm7m per 24 hours²That is, when the order of thickness used is about 5 μιη, these oxygen barrier properties can be compared with PVOH, EVOH (polyethylene glycol copolymer) or polyamide (PA) used when the order of thickness is 5 μιη.

Patent FR-A-2684922 discloses the following, first coat a layer of polymer such as a polyester film with a suspension of amylose containing surfactant, and then at the highest temperature of 1801, the starch Dry it. At the coating level, for example, 0.7 g/m²(Dry weight), good gas barrier performance can be obtained. However, it has not been shown that the same performance can be obtained in laminated packaging materials with a central sandwich of paper or cardboard.

However, although the above-mentioned gas-barrier polymer materials can provide good gas-barrier properties in packaging laminates, they can still be permeated by oxygen to a certain extent, while the oxygen of metal or glass materials used in canned or bottled food The permeability is basically zero. In order to further improve the gas barrier properties, a polymer gas barrier material can be mixed with an inorganic layered compound. Such a gas barrier resin mixture is described, for example, in patent EP-A-590263, in which an extremely good gas and moisture barrier level can be obtained. Patent EP-A-590263 discloses a molded article for producing a gas barrier resin mixture or including a layer of film. The mixture includes a resin and an inorganic layered compound, the compound having 5 μm or less The particle size and the aspect ratio of 50 to 5000, the method includes: dispersing the inorganic layered compound in a resin or resin solution and in

00815202.0 The first state in which the inorganic layered compound swells or cracks together with the solvent/dispersant. The solvent is removed from the suspension, if necessary, in the form of a film, while keeping the layered compound in a swollen state.

SUMMARY OF THE INVENTION We have now discovered that laminated packaging materials with excellent barrier properties, especially gas barriers, can be manufactured using a method that is suitable for the use of such conventional production equipment used in the production of packaging materials using aluminum foil as a barrier layer.

We have now confirmed that in the paper packaging laminate for liquid food packaging, a high-performance oxygen barrier can be obtained by using a gas barrier component including a dispersible or soluble polymer and an inorganic layered compound. performance.

In addition, by avoiding coating the liquid gas barrier component on the central sandwich layer connected to the laminate of the packaging material, when drying the coated paper or cardboard central sandwich, we have eliminated excess water absorption into the central sandwich And this causes the danger of crack formation.

According to the first aspect of the present invention, there is provided a method for producing a laminated packaging material, the packaging material comprising a central interlayer of paper or cardboard and a barrier layer coated on one side of the central interlayer, which is characterized by It consists in that a liquid gas resin barrier composition comprising a polymer suspension (or solution) and an inorganic layered compound is applied as a barrier layer on at least one side of the carrier layer, and is dried during heating to drive off the dispersant or solvent After that, the carrier layer with the coated barrier layer after drying is combined with one side of the center interlayer, and is permanently combined with the side.

Preferably, the inorganic layered compound or the so-called nanoparticulate compound is dispersed in a state of exfoliation and delamination, that is, the thin layers of the inorganic layered compound are separated from each other by a liquid medium. Therefore, the layered compound can preferably be swelled or split by the polymer suspension or solution that has penetrated into the layered structure of the inorganic material during suspension. The inorganic layered compounds can also be swelled with a solvent before they are added to the polymer solution or polymer suspension. Therefore, the inorganic layered compound is dispersed into a delamination state in the liquid gas barrier component and in the dried barrier layer.

The term clay minerals respectively include kaolinite, antiserpentine, smectite smectite, vermiculite minerals or mica-type minerals. Specifically, synthetic hectorite, kaolinite, geostone, perlite, halloysite, antirhodolite, chrysotile, pyrophyllite, montmorillonite, hectorite, sodium tetrasilicate Mica, sodium banded mica, muscovite, pearl mica, vermiculite, phlogopite, green brittle cloud

00815202.0 The first class is considered to be suitable clay minerals.

The best aspect ratio of inorganic layered compound or clay mineral is 50-5000, and its particle size is about 5μιη in the exfoliated state.₀ Preferably, the barrier layer is coated by a liquid film coating method using an aqueous component of a suspension or solution of a barrier polymer containing an inorganic layered compound. For example, PVOH or PVOH and EAA can be applied in the state of an aqueous solution in a mixture with inorganic layered compounds, while starch can be partially dispersed and/or dissolved in a mixture with inorganic layered compounds. Coating is carried out in a hydrated state.

Preferably, the barrier layer includes from about 1% to about 40%, more preferably from about 1% to about 30%, and most preferably from about 5% to about 20% by weight (based on the weight of the dry coating) Inorganic layered compound. If the weight is too small, the gas barrier performance of the coated barrier layer after drying is not significantly improved compared to when the inorganic layered compound is not used. If the weight is too large, the liquid component is more difficult to coat as a coating, and it is also more difficult to handle in the storage tanks and pipes of the coating device.

Preferably, the barrier layer comprises from about 99% to about 60%, more preferably from about 99% to about 70%, and most preferably from about 95% to about 80% by weight (based on the weight of the dry coating) of polymerization Things.

The gas barrier component may include an additive such as a dispersion stabilizer or the like, and the amount should preferably not exceed about 1% of the weight of the dry coating.

The barrier layer is preferably about 0.5 to 20 g/m² (Depending on the type of polymer), preferably about 1 to 10g/m²The dry weight is coated on the carrier layer. If the coating amount is too small, the gas barrier performance will become poor, if the coating amount is too large, there will be the formation of a barrier layer that cannot be deformed and the risk of cracks in it.

The polymer preferably adopts a high-hydrogen-bonding polymer having a hydrogen-bonding group or an ionic group whose weight can reach 20% or more of the polymer molecule. Preferably, the polymer has a coagulated functional group, and may be selected from polyethylene (PVOH), ethylene glycol (EVOH), polysaccharides (such as starch, starch derivatives), carboxymethyl cellulose and others, for example. A cellulose derivative, or a polymer selected from a mixture of two or more of the above-mentioned polymers. In addition, polymers having nitrogen-containing groups can also be used. Preferably, the polymer is a polymer that has gas barrier properties, to be precise, polyvinyl alcohol, starch or starch derivatives.

The aqueous polymer suspension or polymer solution coated as a barrier layer may be dried and optionally cured at a sheet temperature of about 80°C to 200°C. Correct

00815202.0 For non-curable materials, it is best to work at about 801C to 130C.

Preferably, the material including PVOH and inorganic layered compound is preferably dried at the sheet temperature of 8QC to 16°C (preferably 140C to 160°C) in the first process, and then dried in the second process During the process, the sheet is cured at a temperature of 170°C to 230°C, thereby producing a gas barrier layer with improved performance at a relative humidity of 80%. The carrier layer and the barrier layer can optionally be between the two processes Cool down.

It may also include a polymer with carboxylic acid functionality. The polymer can react with polymers with coagulant functional groups during drying/curing.

The polymer having a carboxylic acid functional group can be appropriately selected from ethylene acrylic acid copolymer and ethylene methyl acid copolymer or a mixture thereof.

A particularly preferred barrier layer mixture is a mixture of polyvinyl alcohol, ethylene acrylic acid copolymer (EAA) and inorganic layered compounds. The EAA copolymer is preferably included in the barrier layer at a dry coating weight of about 1% to 20%.

Another barrier mixture that is particularly worthy of preference is a mixture of starch or starch derivatives and inorganic layered compounds.

Optionally, the barrier layer can be dried first and then heated to a higher temperature so that the dried barrier layer can be cured at a temperature of up to 230°C (preferably about 170C). High temperature curing is curing for a short period of time, which may correspond, for example, to the sheet speed commonly used in the production of packaging laminates.

The carrier layer can be made of paper or plastic or paper coated with plastic. The preferred materials will be introduced below. When using paper, the paper is preferably thin paper. In one option, the carrier layer is preferentially used with 5-35 g/m² (E.g. 7-25 g/m²), it is best to be composed of paper with a number of grams of about 10-20 g/m?.

The carrier layer carrying the barrier material and the center sandwich can be combined in various ways.

The carrier layer and the center interlayer that carry at least one of the barrier layers can be combined with each other and bonded together by squeezing a thermoplastic layer therebetween.

Where the carrier layer carries the barrier layer on one side of the carrier layer, it can be combined with the center interlayer by squeezing a thermoplastic layer between the carrier layer and the center interlayer.

Then an outer layer of thermoplastic (preferably polyethylene) is coated on the barrier layer by extrusion.

00815202.0 First, when the carrier layer carries the barrier layer on one or both sides, it can be combined with the central sandwich layer by squeezing a thermoplastic layer between the central sandwich layer and the barrier layer.

If the carrier layer carries the barrier layer on its two sides, a thermoplastic layer can be coated on the outer layer of the barrier material by extrusion.

The plastic layer coated between the central interlayer and the carrier layer or one of the barrier layers may include a substance that acts as a light barrier. When the supporting layer is made of paper or other materials that are not transparent to the naked eye, this structure should be preferred.

We have now confirmed that in packaging laminates, high-performance oxygen barrier properties can be obtained by using a gas-barrier component that includes a suspension of starch and similar materials and inorganic layered compounds.

The gas barrier layer including starch and inorganic layered compound is preferably 0.5 to 5 g/nf, preferably 0.5 to 3 g/m² (E.g. 1.5 to 2 g/m²) Dry coating weight within the range of coating.

It is acceptable to include small amounts of other polymer materials that do not interfere with the desired properties of starch and inorganic layered compounds. For example, the gas barrier layer may also include a small amount of aqueous solution or water-dispersible polymer having a plug functional group, such as polyvinyl alcohol, and a small amount of carboxyl group containing polyolefin, such as ethylene acrylic polymer, and mixtures thereof. The weight percentage of these materials ranges from 0 to 30% (for example, 0 to 20%) or 0 to 10%.

Preferably, the packaging laminate including the deposition in the barrier layer includes a plastic polymer layer directly laminated with the gas barrier layer, and the plastic polymer is preferably a thermoplastic, such as polyethylene. Preferably, the polymer is LDPE. Other thermoplastics that may be used include all other types of polyethylene (including LLDPE, ULDPE, VLDPE, M-PE and HDPE), polypropylene and polyethylene terephthalate.

We have noticed that when polyethylene is coated on a starch-based thin layer at high temperatures (for example, higher than 200°C), the gas barrier performance can be improved, and under appropriate conditions, it can also achieve or Further enter the high-performance range. According to the present invention, the preferred method for obtaining the best performance is to coat the barrier component based on starch or starch derivatives on a thicker center sandwich (as described in patent WO97/16132 That way), but coated on a separate carrier layer. Then, correspondingly, the gas barrier layer is carried by a carrier layer made of paper or plastic.

When paper is used, the paper is preferably thin paper, for example, the carrier layer may have a surface

00815202.0 The weight range is 5 g/m? to 35 g/m² (Preferably 10 g/π? to 25 g/m²) Paper layer. The paper can be pre-coated with a layer of plastic.

After coating the liquid ingredients of starch and inorganic layered compound, the load-bearing layer can be combined with a thicker sandwich material so that the packaging laminate includes a central sandwich with the load-bearing layer on one side. There may be one or more thin layers including a heat-sealing layer on the other side of the center sandwich.

The surface of the carrier layer coated with starch or starch derivative components is preferably substantially impermeable to the liquid vehicle.

The degree of liquid impermeability to the surface can be measured by measuring the surface absorption rate, for example, using Cobb units ("Cobb" = grams (water)/meter-water absorbed on the surface after 60 seconds of exposure to liquid water). . The absorption rate of other liquids can also be measured in a similar way. The method of measuring Cobb absorption rate is specified in SCAN P12-64 and TAPPI T441. The surface absorption rate of plastic is usually about ICobb, while the absorption rate of smooth paper surface is usually about 20 to 30 Cobb. Correspondingly, in order to be used in the present invention, the surface of the substrate should have an absorption rate of 50 Cobb or less, a better absorption rate of 30 Cobb or less, and a best absorption rate of 10 Cobb or less, for example, less than 5 Cobb.

Preferably, the surface of the carrier layer on which the components of the polymer and the inorganic layered compound are coated has a smoothness of 200 Bendtsen or better. The method of measuring Bendtsen's smoothness is specified in SCAN (Scandinavian Technical Standard for Pulp and Paper) P21-67 and in TAPP UM535.

When the substrate is plastic or has a plastic surface, such as a plastic film or a paper carrier layer coated with plastic, the required smoothness can usually be obtained.

One reason why the high-performance barrier properties cannot be obtained in the patent WO97/16132 may be that the central interlayer of the cardboard lacks the necessary impermeability, so the starch aqueous solution used may have penetrated into the surface. This may have adverse effects in many ways. Since the penetration has entered the cardboard like this, the starch layer cannot be a smooth and complete surface. On the other hand, or in addition, drying the paperboard to dry the starch layer can also cause the surface of the paperboard to deform and thereby cause cracks in the starch layer. These problems can be avoided when starch is coated on a separate, smooth and impermeable carrier layer and then laminated on the center interlayer.

The cardboard used in WO97/16312 is generally scheduled to have a surface smoothness of 500-600 Bendtsen_oThis is enough by itself to prevent the starch layer from becoming smooth and intact or

00815202.0 The first generation of thin areas that provide access for oxygen transmission.

In order to avoid cracks, pores or deformation in the barrier layer of the mixture composed of starch or starch derivatives and inorganic layered compounds, it is best that the surface to be coated on it is smooth, that is, the surface of the substrate should have The smoothness is 200 Bendtsen or better (that is, smaller), for example, 150 Bendtsen or less, preferably about 100 Bendtsen or less.

The material used with starch as the carrier layer can also be used with other barrier materials used according to the first aspect of the present invention. However, generally, when starch is used, a plastic film carrier layer or a thin paper carrier layer coated with plastic should be preferentially used, and for the barrier material, for example, PVOH, which can be heated to much more than 100°C for drying and curing , Thin paper or a thin paper carrier layer coated with plastic should be used first.

Although under our conditions of use, certain starches can provide better results than others, the starch used in the present invention can still be any conventional type of starch. Improved potato starch may be preferred, such as Raisamyl 136 (Raiso), which is oxidized hypochlorite. Other qualified starches include cereal starch and its derivatives, such as Cerestar 05773, which is a propylated starch.

The starch derivatives suitable for use in the present invention include oxidized starch, cationic starch and propylated starch.

It goes without saying that when the gas barrier properties of the packaging laminate of the present invention are considered to be provided by a certain specific material such as a mixture of starch or starch derivatives and layered inorganic compounds, such a situation is not excluded here. That is, the gas barrier performance is the result of the interaction between the material and the adjacent layer in the laminate, rather than looking at the overall performance of the material in isolation.

It may be that the improved mechanism of barrier performance recorded when polyethylene is added to the starch layer at high temperature is due to the penetration of polyethylene molecules into the starch to replace the water in the starch grains. of. Other polymers that can produce similar effects can also be used.

The plastic layer can be coated on the mixture of starch (or starch derivative) and inorganic layered compound by melt extrusion, or can be coated by heat and pressure lamination (for example, using a heating radiation) A prefabricated film. Generally, any technique consistent with the preferred embodiment that can provide the desired improvement in the barrier properties of starch can be used.

The plastic layer is preferably fused at a temperature of at least 200°C, preferably 250°C to 350°C, and preferably 250°C to 330°C, in the form of starch (or starch derivatives) and inorganic layered

00815202.0 On a thin layer composed of the first compound.

According to the second aspect of the present invention, there is provided a laminated packaging material, which can be made according to the method of the present invention.

According to the third aspect of the present invention, a packaging container is manufactured by folding and forming a sheet-type or roll-type laminated packaging material obtained by the method of the present invention.

In an independent production process, a liquid component including a polymer suspension (or polymer solution) and an inorganic layered compound is applied as a barrier layer on at least one side of the carrier layer, and during heating The barrier layer is dried in order to drive off the liquid medium (preferably water), and then the carrier layer with the dried coated barrier layer is combined with one side of the center sandwich layer, and permanently combined with the side, so A laminated packaging material with a barrier layer with excellent barrier properties is obtained.

Since the barrier layer is not dried or cured at the high temperature related to the lamination of packaging materials, when the coated paper or cardboard center interlayer is dried, excess water is absorbed into the center interlayer and makes the center of the paper (or cardboard) The risk of dry interlayer and the consequent risk of cracks in the center interlayer are completely eliminated.

If the plastic layer coated between the center interlayer and the paper carrier layer can include a light-blocking substance (the ideal substance is carbon black), an unattractive appearance can be obtained to hide between the center interlayer and the carrier layer. The light blocking layer in a thin layer between the thin paper layers of the barrier layer.

An important advantage of the method proposed in this aspect of the present invention is that the barrier layer produced in a single process can be used in the production of laminated packaging materials when aluminum foil is used as an oxygen barrier layer. The same method and use the same production equipment for production.

Detailed description of the invention The following is a non-limiting example of the packaging laminate obtained by means of the method of the present invention, according to the best embodiment of the present invention, and with reference to the accompanying drawings. In the accompanying drawings: Figure 1 schematically shows a method of producing the carrier layer of the present invention coated with a barrier layer; Figure 2 schematically shows a method of producing the laminated packaging material of the present invention; Figure 3 is A cross-sectional view through the laminated packaging material of the present invention;

00815202.0 Figure 4 is a perspective view from above of a conventional packaging container with a stable configuration made of the laminated packaging material of the present invention; Figure 5 (a, b, c, d) schematically shows the relationship with the present invention The cross-sectional view of the four different packaging laminates corresponding to the specific embodiment; and Figure 6 (a, b, c, d) schematically shows the manufacture of the various packaging laminates illustrated in Figure 5 method.

Referring to the drawings, FIGS. 1 and 2 schematically show the method of the present invention selected as an example for producing the laminated packaging material 10 shown in FIG. 3. The sheet carrier layer 11 is preferably, for example, a thin paper coated with a thin layer of plastic, unwound from the feed roller 12, and guided through a coating device 13 (preferably a liquid film coating device) arranged near the sheet, At least one barrier layer 14 containing a polymer suspension or solution and an aqueous component of an inorganic layered compound is coated on one side of the carrier layer 11 in the form of a firmly bonded barrier layer 14 by the coating device. In the case of a paper carrier layer coated with plastic, the polymer suspension or solution is preferably coated on the side coated with plastic. The amount of the applied solution can be different, but it is preferably an amount that enables the formation of a completely bonded and substantially complete layer after drying, for example, the dry weight of which is about 0.5-20 g /m², Preferably 1-10 g/m²_o In the case of using PV0H and inorganic layered compound components, the supporting layer 11 is preferably composed of a thin paper layer, the thin paper having a thickness of about 5-35 g/m², Preferably 7-25 g/m², Preferably 10-20 g/m' of paper, but the supporting layer 11 can also be a plastic film. However, the thin paper layer has the advantage that the size does not change in the case of an increase in temperature due to drying and possible curing, while plastic does not have this advantage. Generally, when the polymer used needs to be cured at a temperature higher than about 130°C, it is recommended not to use plastic film as the carrier layer.

The barrier layer 14 is coated on the carrier layer 11X in the form of an aqueous component containing a polymer suspension or a polymer solution and an inorganic layered compound. This component includes those properties that need to be added to the packaging laminate in the form of a coating. The polymer, for example, a polymer having a stool functional group, such as polyvinyl alcohol, vinyl alcohol, starch, starch derivatives, carboxymethyl cellulose, and other cellulose derivatives or their mixtures.

The barrier layer 14 may also include a hydrophobic polymer described in patent WO97/22536, such as a styrene-butadiene copolymer.

The barrier layer 14 can also include a functional niche group that can be combined with the above-mentioned polymer.

00815202.0 The first functional group of the polymer, in order to obtain a cross-linked barrier layer 14. This type of polymer may be a polyolefin modified by an acid functional group or a graft copolymer obtained by grafting a monomer containing an acid functional group in an acrylic homopolymer or copolymer. Alternatively, such polymers are copolymers of randomly selected olefin monomers and monomers containing carboxylic acid functional groups, such as carboxylic acid, carboxylic acid liver, metal salt of carboxylic acid or derivatives thereof. Specific examples of suitable polyolefins include homopolymers or copolymers of polyethylene and polypropylene grafted with maleic acid, ethylene acrylic acid (EAA) or ethylene methacrylic acid (EMAA), or optionally selected copolymers. .

Preferably, the barrier layer 14 includes a mixture of polyvinyl alcohol, ethylene acrylic acid copolymer and inorganic layered compound. The mixing ratio of the polyvinyl alcohol and the ethylene acrylic acid copolymer in the barrier layer 14 should enable the polyvinyl alcohol to form a protective covering layer that prevents gas transmission in the packaging laminate. At the same time, the amount of the ethylene acrylic acid copolymer should be sufficient to form a A binder phase, which partially protects the polyvinyl alcohol and partially effectively reduces or prevents liquid migration of the polymer passing through the barrier layer 14.

According to another preferred embodiment of the present invention, the barrier layer 14 includes a mixture of starch and an inorganic layered compound.

After coating, the sheet of the carrier layer 11 is further guided through a drying device 15, such as an infrared (IR) dryer or a hot air dryer, which acts on the coated side of the carrier layer 11 so as to be on the surface of the sheet When the temperature is about 80-100°C (preferably 90-95°C), the water is driven off and the coated barrier layer 14 is dried, and it is used to make the mixture included in the coated polymer In the case of the curing temperature for cross-linking of functional groups, the surface temperature of the sheet can reach up to about 190°C, preferably 17LC.

Finally, the carrier layer 11 of the finished product with the coated barrier layer 14 is rolled up, and then stored, or directly applied to a conventional laminate packaging material 10 with excellent barrier properties. Used in the lamination process.

The carrier layer 11 with the coated barrier layer 14 can be used to produce the packaging material 10 by the same method and production equipment as those used in the production of packaging materials using aluminum foil as the barrier layer. Figure 2 shows a sturdy but foldable central sandwich sheet with a gram of about 100-500 g/m', preferably about 200-300 g/m. The central sandwich sheet can be conventional The fiber layer of paper or 's board with appropriate packaging quality. Guide the central sandwich layer 16 through the gap between the two rotating Feng Kun 17, and between the central sandwich layer 16 and the carrier layer 11 between one or more layers of extrudable thermoplastic 19 (preferably polyethylene ) To paint

00815202.0 During the first cloth, combined with the sheet of the carrier layer 11 with the dried or cured barrier layer 14. As shown in the figure, the barrier material 14 is preferably provided on the outer surface of the carrier layer, but it can also be provided on the inner surface.

Finally, in the process of applying extrudable thermoplastic (preferably polyethylene) thin layers 21, 22 to the two outer sides of the sheet using the extruder 23, the layered sheet is simultaneously guided through the There is a rolling gap between the two rotating spokes 20, so that the finished product of the laminated packaging material 10 of the present invention obtains a cross-sectional structure as shown in FIG. 3. Alternatively, the two extruders 23 may also be arranged sequentially, so as to sequentially extrude the thin layers of thermoplastic material 21 and 22 on the corresponding outer sides of the layered sheet.

The purpose of the two plastic layers 21 and 22 is that, on the one hand, it can protect the packaging material 10 from the intrusion of moisture and moisture from the outside. In addition, it can also be sealed by conventional so-called heat sealing. The key function is that the plastic layers facing each other can be joined together by surface fusion while providing heat and pressure. The heat-sealing process uses a mechanical method to achieve a strong liquid-tight sealing joint during the transformation of the packaging material into the finished packaging container.

The outer plastic layer 22 on the side where the central sandwich 16 coated on the packaging material 10 can be used to face the outside in the finished packaging container may be provided with an appropriate imprint for identifying the decoration and/or information properties of the packaged product.

Using the laminated packaging material of the present invention, the existing packaging and filling machine can be used to produce liquid-tight, dimensionally stable packaging with excellent oxygen barrier properties. The machine can make the material in a continuous production process. The material is formed, filled and sealed into the packaged product 50. An example of such a conventional packaging container 50 is shown in FIG. 4.

By first merging the longitudinal edges of the roll-shaped laminated packaging material 10 into a tube filled with the articles intended to be contained, then each package 50 is sealed with the tube by repeated transverse sealing below the height of the article. The flakes are separated. The packages 50 are separated from each other by cuts in the transverse sealing area, and the required geometric shape is usually parallelepiped through the final folding forming and sealing process.

It should be noted that the various packaging laminates of the present invention may include multilayer laminates other than those shown in the drawings. Therefore, it is obvious to those skilled in the art that the number of layers can be changed, and the description of the illustrated embodiment should not be considered as a limitation to the present invention.

Figure 5a schematically shows a simple embodiment of the present invention with general reference numerals

00815202.0 No.

10a is a cross-section of the packaging laminate, and Figure 6a schematically shows the method used to manufacture the load-bearing layer structure used in the laminate 10a (indicated by the reference number 20a). The laminate 10a includes a load-bearing layer 11, the The surface of the carrier layer has a smooth and substantially non-hygroscopic tissue. The supporting layer 11 may be a plastic film or a thin paper having the surface properties. A tissue paper substrate with a surface weight of about 5-35 g/* cannot absorb much from the liquid barrier component, not only because it is very thin, but also because the tissue paper available on the market usually has very Flat and smooth hard surface. One type of paper that is particularly suitable for this purpose is called cellophane, but it is quite expensive compared to other papers available on the market. A more suitable paper is MG kraft paper (Munks j0) with a surface weight of about 5 to 35 g/nf. MG indicates that the paper is smooth on one surface, and it is best that the surface should be coated with starch. When the barrier component includes starch or starch derivatives, the supporting layer 11 is preferably a plastic film or a thin paper supporting layer coated with plastic because this thin paper supporting layer has the most excellent surface properties.

Coat a thin layer containing aqueous components of starch solution or suspension and inorganic layered compound on top of the sheet of the base layer 11, and guide the sheet from a feeding drum (not shown) in the direction of the arrow Go to coating station 13a. The water-containing component is preferably applied by a liquid film coating technique known in the prior art of aqueous solution and suspension coating, which is also called "suspension coating" or "wet coating". However, for the present invention, In other words, other coating techniques are also feasible, depending on the viscosity of the ingredient. The aqueous component including starch is preferably applied in such an amount that the barrier layer 14 after coating and drying has a thickness/surface weight in the range of about 0.5 to 3 g/n?.

The sheet coated with the aqueous solution is further directed to a drying station 15a, where the sheet is dried by removing water from the coated aqueous starch solution by means of a drying device. Drying can be performed by any conventional device, such as an infrared (IR) dryer or an air dryer. It is best to dry at a temperature of about 80-100°C.

After leaving the drying station, the dried flakes with the upper layer 14 of starch and inorganic layered compounds are further guided to an extrusion station 23a where the flakes and barrier layer are further laminated with a plastic layer twenty one. Laminating the starch surface on the plastic layer is achieved by fusing the surface between the plastic layer and the layer including the starch 14, and this melting is achieved by simultaneously applying heat and plastic. Preferably, while the sheet is guided through the gap between the two rotating cooling spokes 24a, the molten polymer is also squeezed onto the dried starch layer, thereby forming a packaging laminate Top three of 10a

00815202.0 The finished packaging laminate of the first layer, as shown in the cross-sectional view of FIG. 5a, has a plastic outer layer 21 laminated on the starch layer 14. The extruded plastic material (preferably) is a thermoplastic polymer, more preferably a polyethylene, most preferably low-density polyethylene (LDPE), which can effectively transform the packaging laminate 10a by heat sealing In a dimensionally stable, liquid-tight packaging. The extrusion temperature should be at least 200°C, preferably from about 250°C to about 330°C.

Another method is that the surface fusion between the starch layer 14 and the plastic layer 21 can be achieved by simultaneously applying heat and pressure to laminate a prefabricated thermoplastic film on the dried starch layer 14, preferably It is to make the starch-coated substrate and the plastic film pass through a thermal gap to achieve, whereby the temperature provided by the thermal radiation is at least 200 °C, up to 350 °C, preferably from about 250 Ό To about 330C.

The three-layer laminate thus made can then be laminated on the cardboard core 16 as shown in Figure 5a by extrusion compounding an intermediate layer 19 of a thermoplastic polymer, preferably polyethylene, to produce a packaging laminate. 10a.

Fig. 5b schematically shows a cross-sectional view of a packaging laminate 1 Ob according to another embodiment of the present invention, and Fig. 6b schematically shows a manufacturing method of the laminate 10b (indicated by the reference 2 Ob).

According to this embodiment of the invention, the substrate or carrier layer 11 is coated with a water-containing barrier composition on both sides thereof in the same manner as described in the embodiment of Figs. 5a and 6a.

Therefore, the packaging laminate 10b manufactured by the method of FIG. 6b includes a carrier layer 11 as described above, a barrier component layer (14, 14,) coated on each side of the base layer 11, and a laminate The outer plastic layer (21, 2U) on the outer side of the corresponding barrier layer. In the case of starch in the barrier layer, the outer plastic layer is coated by fusion with the surface of the starch barrier layer obtained by simultaneously applying heat as described above. Because of this layered structure, a double gas barrier effect can be obtained.

Therefore, using the method of FIG. 6b, a thin layer of water-containing barrier composition can be coated on each side of the sheet of the carrier layer 11, which is moved from a feed roller (not shown) in the direction of the arrow. Be guided to the coating station 13b. The water-containing components including starch and inorganic layered compounds are preferably coated on each side of the base layer 11 by suspension coating technology in such an amount that the starch layer 14 after coating and drying should be applied and dried. 14, each layer has a thickness/range from about 0.5 to about 3 g/m²The surface weight.

The water-containing components including PVOH and inorganic layered compounds are preferably coated in such an amount that each of the coated and dried starch layers 14, 14,

00815202.0 has a thickness/range from about 1 to about 10g/m²The surface weight.

The sheet coated with the aqueous solution is further directed to a drying station 15b where the sheet is dried by means of a drying device in order to remove water from the coating layer of the aqueous starch solution. As mentioned above, it is best to dry in a temperature range of about 80-100°C. Optionally, the subsequently dried barrier layer can be cured at a high temperature as described above.

After leaving the drying station, the dried sheet with an upper barrier layer 14 and a lower barrier layer 14 is further guided to an extrusion station 23b by a turning crane 25, where each side of the sheet is Another plastic layer 21, 21 is applied. Therefore, the plastic layers 21 and 2L are applied by corresponding extruders 26, 27 working on each side of the sheet. While the sheet is guided through the gap between the two rotating cooling cranes 24b, the molten polymer is also squeezed onto the dry barrier layer (the substrate is the same as described above), thereby forming A finished packaging laminate 10b, as shown in the cross-sectional view of Fig. 5b. The laminate 10b is combined with a center interlayer and forms a packaged product as shown in FIG. 4.

Fig. 5c schematically shows a packaging laminate 10c according to another embodiment of the present invention, and Fig. 6c schematically shows a manufacturing method of the laminate 10c (indicated by the reference number 20c).

The thickness of the paper or cardboard used in the present invention is usually in the range of about 100 μm to about 400 μm, and its surface weight is about 100-500 g/m², Preferably about 200-300 g/m\ According to method 20c, the first sheet of the center sandwich 16 is guided from the feed roller (not shown) to the extrusion laminating station 28 in the direction of the arrow, with coating The second sheet of the base layer 11 of the drying layer 14, 14 of the barrier composition on each side passes through a thermoplastic polymer, preferably polyethylene, preferably LDPE, in the middle of the melt extrusion at this station The thin layer 19 is stacked and laminated on the central interlayer.

The sheet 16 of the laminated center sandwich, barrier layer and load-bearing layer is further guided to the extrusion station 29, where the thermoplastic outer layers 21, 22, for example, preferably LDPE, are further extruded on the laminate 16 at this station^fOn each side of the base layer 11, the barrier layer on the outer side of the base layer 11 opposite to the side laminated on the upper side of the central sandwich and the opposite side of the central sandwich 16 are coated with extruded thermoplastic, thereby forming a layer 21 and 22.

Suitable thermoplastics for the outer layer 14 are polyolefins, more preferably polyethylene, preferably low-density polyethylene, such as LDPE, linear LDPE (LLDPE) or single-site catalyst metallocene polyethylene. Eventually will form the outer side of the packaging container made of packaging laminate

00815202.0 The first outer layer 22 may instead be coated on the sandwich sheet 16 in a step before the coating and drying steps of the barrier component are performed.

Fig. 5d schematically shows a packaging laminate 10d according to another embodiment of the present invention, and Fig. 6d schematically shows a manufacturing method of the laminate 10d (indicated by reference numeral 20d). The packaging laminate 1 Od is formed by coating and drying a thin layer of a water-containing barrier component including a suspension or solution of a polymer and an inorganic layered compound 14 on the supporting layer 11, and the supporting layer It is composed of a plastic film, as described in the initial process of Method 20a above.

According to the method 20d, the first sheet of the center sandwich 16 is guided from the feed roller (not shown) to the extrusion compounding station 28 along the direction of the arrow, with a dry layer coated with a barrier component on one side A second sheet of the carrier layer 11 is superimposed on the station so that the barrier layer 14 is aligned with the center sandwich and passed through a thermoplastic polymer, preferably polyethylene, preferably LDPE, melt-extruded The pressed middle layer is laminated on the center sandwich. The carrier layer 11, that is, the plastic film, can form an inwardly directed outer layer of the packaging laminate in the packaging container made from it, thereby providing the inner layer of the container. In the last extrusion station 29, inside, the outer thermoplastic layer 17 is coated by extrusion coating.

For the example described in the patent WO97/16312, a problem with the laminate is that during the lamination and conversion process, the manufacture of the laminate needs to be the same as the current general laminate paper that uses aluminum foil as a gas barrier layer. The machine is completely different from the machine. This packaging laminate is made by extruding a cardboard matrix onto a barrier film made of polyethylene. On the contrary, it can be seen from the above description that a carrier layer of plastic or tissue paper carries a barrier component coated on one or both of its surfaces. The barrier component includes a hydrogen-bonded polymer and an inorganic layered compound. Or no plastic has been coated on the starch layer or one or both of the barrier components. The plastic or tissue carrier layer can simply replace the aluminum foil with less adjustments in conventional machinery. If necessary, the preparation of the gas barrier layer carried on the carrier material can be done separately on another device, so that the existing retrofit production line in the factory can be easily adapted to use the new material.

Therefore, another important advantage of the preferred embodiment of the method that has been described is that the process of coating and drying the barrier component of the liquid gas can be carried out outside the lamination line, thus, in the manufacture of packaging with a central sandwich When laminating boards, it avoids the cost of transformation and renovation of expensive laminating equipment. By coating the barrier layer on a thin carrier layer, such as a plastic film or a thin paper with a smooth surface that is substantially non-hygroscopic, then

00815202.0 The other plastic layer and the center interlayer are laminated again. Therefore, the lamination operation can be carried out using the same equipment and methods as currently used when laminating aluminum foil and inner layer.

The dimensionally stable, liquid-tight packaging of the disposable type can be prepared from the packaging layered board 10 according to the conventional "form-fill-seal" technique, preferably pre-folded and colored decorated sheet or tape type wool. After the embryo is manufactured, the packaging can be shaped, poured and sealed according to this technology through reasonable modern packaging and infusion machinery. For example, this kind of packaging can be manufactured from a sheet of packaging laminates by first transforming the sheet into a tube and connecting the two longitudinal edges of the tube by heat sealing in longitudinally overlapping seams. Together. The tube is then filled with suitable items, such as liquid food, and the tube is divided into several individual packages by repeated transverse sealing of the tube, which is sealed in the tube below the height of the article and transversely passes through the tube. Longitudinal axis. These packages can finally be separated from each other by a transverse cut along the transverse seal, thereby forming a pillow-shaped sealed package. The pillow-shaped package can be sold as such, or the package can first be given a desired geometric shape, usually a parallelepiped shape formed by an additional forming and heat-sealing process in a well-known manner.

Using the above-mentioned methods and materials, an aqueous barrier composition including a starch (or derivative) suspension/solution and an inorganic layered compound is coated on the base layer used to support the barrier layer, and the base layer is Composed of a specially selected material, combined with the subsequent drying and lamination of the plastic layer by heat fusion on the plastic surface, it is comparable to the packaging laminate described in the patent WO97/16312 The oxygen barrier performance inside the packaging laminate is greatly improved. The improvement in the gas barrier properties of the laminated barrier layer has completely reached the excellent level of the so-called high performance barrier layer. When the base layer is composed of polymer or has a polymer-coated surface, the best gas barrier effect can be achieved. Compared with the performance of previously known ingredients including starch, it has a surface weight of about A thin paper layer of 7-35 g/m, and having a smooth and substantially non-hygroscopic surface will provide improved gas barrier properties.

In the case of a barrier component including starch, when a plastic bearing layer or a bearing layer with a plastic surface is used, the best gas barrier performance can be obtained. It can be considered that the best performance is at least part of the surface quality, that is Smoothness and liquid resistance, the result. However, the mechanism of action obtained by using the fusion bonding interface between the starch polymer and the plastic layer is not yet fully understood. The best gas barrier performance may also be partly due to the formation of such a layer on the two sides of the starch-containing layer. As a result of the interface, due to the coating

00815202.0 The carrier layer of the first powder component is a plastic layer, so when heat is applied to the starch-containing layer and the plastic layer, the same phenomenon may occur at the interface.

It is advantageous for the coating amount of the starch-containing gas barrier layer of the present invention to be in the range of about 0.5 to 5 g/n? dry weight. When the amount is less than 0.5 g/n?, the allowable deviation of layer thickness and gas barrier performance will become less reliable. On the other hand, when the amount exceeds about 3 g/30, the risk of the starch-based barrier layer becoming brittle and non-deformable will increase. However, the amount is up to about 5 g/m^?Dry weight coating weights are possible, and for certain types of packaging and use, even larger coating weights are acceptable. The gas barrier properties of the starch component layer generally increase as the thickness increases. The best and preferred coating amount range of starch is about 1.5 to about 2 g/m. Preparation Example 1 The shape of the stripped flakes of about 1-5% by weight will have an aspect ratio of about 505,000 minerals. An aqueous suspension made of particles (natural materials, such as microcrystalline kaolin, or synthetic materials, such as laponite) and about 5%-30% by weight of PVOH (its molecular weight is 16000-200000g/mol, saponification rate 95-100%) Mix at 60-90°C for 2-8 hours. The mineral particle suspension of the exfoliated layered flakes can be stabilized by stabilizing additives. Another method is to strip the layered mineral particles in a PVOH solution at 60-90°C for 2-8 hours. The ethylene acrylic acid copolymer suspension is added to the water mixture of PVOH and mineral particles. The resultant synthetic mixture is about 1 to about 10g/m²The dry weight of the coating is dispersed and coated on the paper carrier layer coated with thin plastic. The wet coating is implemented in the form of a solution/suspension in water, and is dried when the surface temperature of the sheet is 100-150°C, and then cured at 170-190°C.

Preparation Example 2 When preparing the barrier material/carrying material composition, starch is also formed by mixing 10% by weight of starch with water at room temperature to form a suspension from a dry powder state to prepare it for coating use.

A water suspension made of mineral particles (natural materials, such as microcrystalline kaolin, or synthetic materials, such as laponite) with a peeled flake shape of about 1% to 5% by weight and an aspect ratio of about 505,000. The solution and the aqueous solution/suspension of starch are mixed for 2-8 hours at 60-90. The mineral particle suspension of the exfoliated layered flakes can be stabilized by additives

00815202.0 The first stabilization. Another method is to strip the layered mineral particles in a starch suspension at 60-90°C for 2-8 hours.

The synthetic suspension of starch and mineral particles was stirred and heated from 90°C to 95°C, and kept at this temperature for 30 minutes. During heating, starch swells.

If possible, for example for Raisamyl 306 (Raiso), the starch should be cooled to room temperature before use in painting. However, when doing so will cause the starch to become colloid, for example for CERESTAR, the starch should be heated (60Γ) for coating.

Using the liquid film coating/suspension coating method, a wet weight of about 10 times the required dry coating weight can be coated on the sheet-shaped carrier layer.

For ingredients containing starch, the first drying process in which IR is used to heat the surface temperature of the sheet to 80 to 100°C can speed up the drying process, and then the hot air drying process is carried out. In this process, the starch is coated It is dried by hot air under the condition of sheet speed of lm/min and temperature of 110U. Generally, the surface temperature of the sheet is 80 to 100C is appropriate and depends on the linear speed of the sheet.

Preferably, the dried starch layer is coated with LDPE by extrusion. As mentioned above, about 25 g/m? of LDGE is extruded onto the dried starch layer at 200m/min, 325C, and the cooling system is at 10-15°C. The distance between the extrusion die and the sheet is usually 1030 cm. The extruded LDPE hits the sheet just when it enters between the cooling rod and the balance pressure rod.

It is obvious to a person of ordinary skill in the art that the present invention is not limited by the illustrated embodiments, and various modifications can be made to the present invention as long as it does not deviate from the scope specified in the appended claims. Changes and changes. For example, the structure of the packaging material that has been described is naturally formed, and is not limited to the number of layers described (the number of layers may be more or less), and the number of layers can also be based on the given document using the packaging material. Change freely upon request.

00815202.0