JP3043853B2 - Gas barrier multilayer laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer laminate having excellent anti-fogging properties and gas barrier properties, and further having an excellent interlayer adhesion strength between laminated films, and more particularly to adhesion of a multilayer laminate by transfer of an anti-fogging agent. To prevent the lowering of the interlayer adhesion strength of the agent layer,
The present invention relates to a gas-barrier multilayer laminate excellent in anti-fog performance.

[0002]

2. Description of the Related Art Conventionally, gas barrier multilayer laminates used for food packaging, cosmetic packaging, pharmaceutical packaging and the like are made of aluminum foil, saponified ethylene-vinyl acetate copolymer resin (hereinafter abbreviated as EVOH), polyvinylidene chloride, or the like. Generally, a laminated film in which a metal foil or a gas barrier resin film such as a copolymer resin, a polyamide resin, or a polyacrylonitrile copolymer resin is bonded is used. That is,
To give a heat-sealing property to a base film made by laminating a barrier resin film and cellophane, biaxially oriented polyethylene terephthalate, biaxially oriented polypropylene film, etc., a laminated film in which a polyolefin-based resin is in one outermost layer is used. Have been.

[0003] Adhesion between layers of these laminated films is performed by a dry lamination molding method using a so-called dry laminating adhesive such as urethane type or acrylic type, and an organic titanium type, polyethylene imine type, polyethylene imine type or isocyanate type is used as a base film. Extrusion lamination molding and coextrusion lamination methods in which low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, etc. are coated at high temperature by coating with an anchor coating agent (hereinafter abbreviated as AC). And the like, and by a co-extrusion molding method using a known adhesive resin without using an anchor coat agent.

[0004] A known adhesive resin (hereinafter abbreviated as AD).
For example, there is a resin obtained by graft polymerization or copolymerization of an unsaturated carboxylic acid, an unsaturated carboxylic anhydride or an ester monomer to a polyolefin resin. As a grafting method, the above-mentioned graft component is heated with an extruder or the like together with an organic peroxide to melt-graft-modify the polyolefin resin, or the polyolefin resin is dissolved in hot xylene and the above-mentioned graft component is grafted with an organic peroxide. Can be obtained in a way.

[0005] Examples of the grafting agent include monomers such as unsaturated carboxylic acids, acid anhydrides and esters. For example, methacrylic acid, acrylic acid, ethacrylic acid, glycidyl methacrylate, 2-hydroxyethyl acrylate, methacrylic acid 2
-Hydroxyethyl, diethyl maleate, monoethyl maleate, di-n-butyl maleate, maleic acid,
Maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, 5-norbornene-2,3-anhydride, citraconic acid, citraconic anhydride, crotonic acid, crotonic anhydride, acrylonitrile, methacrylonitrile, acrylic Sodium acrylate, calcium acrylate, magnesium acrylate and the like. These graft polymers are described in U.S. Pat. Nos. 4,026,967 and 3,953,655.
Specification, JP-A-51-98784, JP-B-44
These are described in detail in, for example, JP-A Nos. 15423 and 49-4822. Of these, maleic anhydride graft-modified to a polyolefin resin is generally used because of its cost and ease of modification.

In a package using such a multilayer laminate, a polyolefin resin is usually used as the innermost layer in consideration of heat sealability. However, since the polyolefin resin is generally a hydrophobic resin, when the inside of the package is in a humid atmosphere, or when the temperature for freezing or refrigeration reaches the dew point and the water vapor pressure inside the package becomes a saturated water vapor pressure, this occurs. Condensation of water vapor occurs at the boundary of the temperature, and in a remarkable case, condensed water droplets make it impossible to identify the contents or cause the contents to deteriorate due to falling water drops. To solve these problems, (1) apply or paste a coating layer of a polymer compound having a contact angle with water as small as possible, such as polyvinyl alcohol resin, polymethyl acrylate, or cellulose acetate, on the inner surface of the package. A method of adsorbing or absorbing moisture in the film layer (2) Coating or kneading a surfactant or the like to minimize the contact angle between the film substrate on the inner surface of the package and water. (3) Conversely, a method is used in which the contact angle is made as large as possible to form a film that repels water without forming water droplets (4) Automotive As is known for windshields and rear windows, there is a method of forcibly heating the surface to prevent dew condensation.

Of these, the hydrophilic polymer compound (1) is inferior in compatibility with the polyolefin resin, so that it is difficult to apply or bond it and the lamination strength is weak. Not valid. A well-known resin used in the method (3) is a polyvinylidene fluoride resin, but this resin is not only expensive but also inferior in compatibility with the polyolefin resin, and has a higher heat resistance than the polyolefin resin. There are problems such as poor sealing characteristics. The method (4) cannot be used for a laminated film for applications such as food containers.

Accordingly, the method of (2) is used as a laminated film for packaging containers of foods and the like that require anti-fogging properties. As a more specific method for these, for example, Japanese Patent Publication No. 60-34460 discloses a method in which an adhesive layer made of an adhesive or an anchor coat agent is provided on a surface of a base film including a printing layer, and the polyolefin layer is further provided. There is disclosed an antifogging film for food packaging comprising a polyolefin layer kneaded with a nonionic surfactant such as a sorbitan fatty acid ester, a polyoxyethylene sorbitan fatty acid ester, or a polyoxyethylene fatty acid ester. JP-A-2-289634 discloses a method of adding a mixture of a glycerin-mixed fatty acid ester and diethanolamide to a polyolefin resin in an amount of 0.05 to 2.0% by weight, and further discloses a "functional composite film / sheet" (processing). Technical Research Society February 25, 1986) 26
On page 6, "Anti-fogging composite film / sheet" introduces conventional techniques.

However, in these conventional multilayer laminates, the antifogging agent added and kneaded to the polyolefin layer migrates with time to polar substances such as an adhesive layer and a gas barrier layer,
The anti-fogging property is reduced and water vapor is condensed on the inner surface of the multilayer laminate,
Transparency deteriorated, the commercial value declined, and water droplets were locally aggregated, causing decay. In addition, the transfer of these antifogging agents has a problem that the interlayer adhesion strength between the gas barrier layer and an adhesive layer such as an anchor coating agent or an acid anhydride-modified polyolefin resin is extremely reduced.

For example, by a co-extrusion molding, a multilayer laminate comprising polypropylene (hereinafter abbreviated as PP) and EVOH and a polyethylene resin having an antifogging property (hereinafter referred to as AF-PE)
Abbreviated. ) And PP / AD (1) / EVO
In order to impart anti-fog properties to the gas barrier coextruded film composed of H / AD (2) / PP,
PP in which C is applied, and a polyethylene resin (hereinafter abbreviated as PE) is extruded and laminated at high temperature between AF-PE films.
/ AD (1) / EVOH / AD (2) / PP / AC / P
EVOH / AD in the multilayer laminate composed of E / AF-PE
There is a problem that the portion (2) and the AC / PE portion are easily peeled off.

[0011]

In the prior art, an antifogging agent which causes a reduction in antifogging property and interlayer adhesion strength, etc., is applied to a polar substance or a polar resin such as an adhesive layer or a gas barrier layer over time. There was a problem of easy migration. Accordingly, it is an object of the present invention to prevent a decrease in adhesive strength due to migration of an antifogging agent and to obtain an excellent gas barrier antifogging multilayer laminate without a reduction in antifogging properties.

[0012]

According to the present invention, there is provided a composition comprising (a) a base film having a transparent gas barrier resin layer as a constituent layer and (c) a polyolefin antifogging layer containing a nonionic surfactant. The above problem was solved by developing a gas-barrier multilayer laminate characterized by further providing at least (b) an adhesive layer made of a polymer of a siloxane compound directly in contact with the base film.

As the nonionic surfactant used in the present invention, those having an HLB of 3 to 18 are preferably used. When the HLB of the nonionic surfactant exceeds 18, the antifogging effect is improved, but the tendency of bleeding to the film surface is increased, and the persistence of the antifogging effect is extremely reduced. On the other hand, the lower the HLB, the lower the bleeding property and the longer the sustainability, but the lower the antifogging effect. Therefore, an HLB of 7.0 or more and 9.5 or less is a particularly preferable range from the balance between antifogging property and sustainability.

[0014] Surfactants used as antifogging agents include sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene fatty acid esters, polyglycerin fatty acid esters, oxyethylene / oxypropylene block polymers, polyoxyethylene. Alkyl ethers, polyoxyethylene alkylphenol ethers, or a mixture thereof can be mentioned.

The mixing ratio of the nonionic surfactant to the polyolefin resin is 0.05 to 8% by weight, preferably 0.1 to 5% by weight. When the amount of the nonionic surfactant is more than 8% by weight, it is suitable for maintaining the antifogging property for a long period of time, but the film becomes sticky and adversely affects the heat sealing property at the time of bag making after film formation. In an extreme case, the nonionic surfactant bleeds on the surface of the multilayer laminate, and the films adhere to each other during bag making, making it extremely difficult to open the bag. Further, the antifogging property expected to be less than 0.05% by weight cannot be exhibited. The method of mixing the anti-fogging agent may be either a method in which the mixture is melt-blended with a polyolefin resin in advance using a Banbury mixer or the like and a master batch is formed to a predetermined mixing ratio, or a method of directly mixing with the polyolefin.

Conventionally, a film to be laminated is previously coated with a titanium-based coupling agent, a polyethyleneimine or an isocyanate-based anchor coating agent by a gravure roll method, a dropping method, a barcode method, or the like, and then the polyethylene-based resin is heated to 240 ° C. Heating and laminating with the base film by heating as described above, or changing to polyethylene resin, ethylene-vinyl acetate copolymer resin or ethylene-ethyl acrylate-
Laminated using maleic anhydride terpolymer resin or the like.

In the present invention, a siloxane compound is applied and laminated as an adhesive layer which does not require the use of an anchor coat agent instead of the conventional adhesive layer using an anchor coat agent. In the present invention, the siloxane compound may be a polymer (oligomer) obtained by hydrolysis of an organic silane or a silane coupling agent. Ethylene; a silane having a polymerizable unsaturated group such as vinyl, acryl, or allyl; a vinyl compound, an acryl compound Hydro-crosslinked product of a copolymer derived from an ethylenically unsaturated compound such as a compound; a copolymer of an olefin and a siloxane compound having a polymerizable unsaturated group; a graft copolymer of a siloxane compound having a polymerizable unsaturated group with a polyolefin; Examples of the polymer include a polymer or an oligomer having a siloxane group in a main chain or a branched chain such as a polymer.

If the thickness of the adhesive composed of these siloxane compounds is 2 μm or less, migration of the antifogging agent cannot be prevented, and delamination and deterioration of the antifogging performance are not preferred. Meanwhile, 1
When the thickness is 5 μm or more, the multilayer laminate becomes too rigid and causes bending fatigue resistance, which is not preferable. More preferably 4
It is good to apply so that it may be up to 13 μm.

Ethylene: Copolymers of a silane compound having an olefinically unsaturated group and an ethylenically unsaturated compound obtained by water-crosslinking are disclosed in JP-B-62-23779, JP-B-62-15580, and JP-A-62-15580. 23797
JP-A-57-26696 and JP-A-63-3942.
No. 7, No. 61-155412, etc., and further, as described in WO 89/00501, a method of copolymerizing a polyolefin resin and a siloxane compound at high pressure in the presence of a radical polymerization initiator. The presence of an organic peroxide (radical polymerization initiator) using an extruder described in JP-A-63-172712, JP-B-48-1711 and JP-A-47-8389. There is a proposal on a method of grafting a siloxane compound to a polyolefin resin below. In addition, a silane coupling agent typified by a glass fiber treating agent is well known as one utilizing a siloxane monomer.

In general, siloxane polymers are more permeable to gas components than polyolefin resins and other polymers. For example, as disclosed in Polymer Processing, Vol. 36, No. 3, page 11 (1987), use for gas permeation is considered. However, in the present invention, a uniform film is formed by using a siloxane compound, in particular, a silane coupling agent containing an amino group as an adhesive, and the uniform film is formed with a thickness of 2 to 15 μm.
m, the adhesive layer serves as a barrier layer for preventing migration of the antifogging agent (surfactant), preventing a decrease in the interlayer adhesion strength of the multilayer laminate and a decrease in the concentration of the antifogging agent. It is thought that antifogging property can be maintained.

The reason why a siloxane containing an amino group is particularly effective in the present invention is not completely understood, but one of the reasons is related to wetting the surface of the polyolefin film. It is believed that the negative surface charge above or just below the surface attracts the cationic amino-containing siloxane when in the methanol solution and wets the film surface. It is also conceivable that the carboxyl group on the surface of the polyolefin film attracts the amino group of the siloxane and moistens the surface of the polyolefin film, particularly in the laminate polyolefin film subjected to the corona discharge treatment. When a silane mixture containing an amino group is used as a precursor of a gas barrier resin as an antifogging agent on a polyolefin film, a siloxane compound obtained by hydrolyzing the silane needs to be a monomer in order to be able to wet the surface. Have to be mixed and then co-hydrolyzed. Preferred siloxane compounds include vinylbenzylaminosilane or a hydrolysis-polymer of vinylbenzylaminosilane and vinyltrimethoxysilane.

Examples of the method for producing the siloxane-containing adhesive of the present invention include US Pat. No. 4,803,126 and JP-A-2-286331. Specifically, for example, a solution obtained by dissolving a siloxane monomer in alcohols and adding a small amount of water to the portion of the polyethylene terephthalate resin layer is heated and heated to crosslink the siloxane portion. By extruding a low-density polyethylene resin at a high temperature between the polyolefin resin film and the polyolefin resin film into which the resin is kneaded, a gas-barrier multilayer laminate can be obtained.

The polyolefin mixed with the antifogging agent needs to be heat-sealable, and it is possible to use low-density polyethylene, linear low-density polyethylene,
Examples include high-density polyethylene and polypropylene.

The gas barrier resin used in the gas barrier multilayer laminate of the present invention includes saponified ethylene-vinyl acetate copolymer resin, polyvinylidene chloride copolymer resin, polyamide resin, and the like, which are generally used as gas barrier resins. Polyacrylonitrile copolymer resins can be used.

The substrate film may be a laminate of a gas barrier film and a biaxially oriented polyester film, a biaxially oriented polypropylene film, or the like. When laminating these substrate films and AF-PE, a siloxane compound is used. The present invention is effective as long as an adhesive is used. Therefore, a sufficient effect of the present invention can be obtained in a combination of a base film / adhesive / AF-PE or a base film / adhesive / (polyolefin or other resin) / AF-PE.

[0026]

In the multilayer laminate according to the present invention, a siloxane compound adhesive layer is provided between the AF-PE layer and the base film having the transparent gas barrier resin layer as a constituent layer, thereby preventing the multilayer laminate. It is thought that the fogging agent is blocked by the adhesive layer and the adhesive strength can be maintained at a high level, so that high gas barrier properties can be maintained, delamination is prevented, and antifogging performance can be maintained for a long time.

[0027]

Now, the present invention will be described in further detail with reference to specific examples. The evaluation of antifogging performance and the evaluation of delamination were performed by the following test methods.

[Anti-fogging performance] A multi-layer laminate having an anti-fogging agent-containing polyolefin film laminated thereon was prepared by mixing an anti-fogging layer with an anti-fogging agent mixed on the upper surface of a cylindrical vessel having a radius of 5 cm containing water at 70 ° C. (AF-PE layer) was covered without any gap so as to be on the water side, and after 30 minutes, the state of the film was visually evaluated. At this time, those whose transparency was inhibited by adhesion of water droplets and the like were represented by x, and those having no change in transparency were represented by ○. Further, as a long-term performance evaluation, the film was evaluated immediately after film formation, and after one month and six months after forming stored at 25 ° C. and a humidity of 65 RH%.

[Evaluation of Peeling] The layers in which the antifogging agent was mixed were heat-sealed at 190 ° C. under a sealing pressure of 2 kg / cm ² , using Tensilon, UTMIII manufactured by Toyo Seiki Co., Ltd. 15 mm width peeling strength when peeling at a peeling rate of 300 mm / min. And peeling location (x if the peeling location is the adhesive layer or adhesive layer peeling of the base film, In the case of cohesive failure, it was represented by ○). In addition, immediately after film formation as a long-term performance evaluation as well as anti-fog performance evaluation,
And molding 1 stored at 25 ° C. and 65 RH% humidity
After 6 months and 6 months after molding, evaluations were also made.

(Example 1) Homopolypropylene (manufactured by Showa Denko KK, show aroma, MI = 7.0 g / 10 mi)
n), maleic anhydride-modified PP adhesive layer resin (manufactured by Mitsui Petrochemicals, Admer QF551), Nippon Gosei Kagaku Co., Ltd. having an ethylene content of 29 mol%, Soarnol DT (E
VOH) was formed by a co-extrusion molding method using a 65 φ 3 type 5-layer T-die apparatus manufactured by Toshiba Machine Co., Ltd. so as to have a layer configuration of PP / AD / EVOH / AD / PP (the die temperature was 21).
0 ° C). At this time, the thickness of each layer is 20 μm for the PP layer, 3 μm for the AD layer, and 12 μm for the EVOH layer.
μm (this film is referred to as a base film). On one surface, vinylbenzylaminosilane (Z-6032, manufactured by Dow Corning) was applied at 25 ° C for 24 hours.
Time-hydrolyzed 10vol% and methanol 90v
ol% was applied and heated by a bar coating method to obtain a coating layer having a thickness of 5 μm. On the other hand, H
A linear low-density polyethylene (Showa Denko, Shorex, MI = 5 g / M) mixed with 0.5% by weight of a diglycerin fatty acid ester having an LB of 7.3 using a super mixer SMV-20 manufactured by Kawada Seisakusho. 10 minutes, density = 0.
920 g / cm ³ ) was formed into a single-layer film having a thickness of 20 μm (die temperature: 210 ° C.) using a 40φ single-layer T-die forming machine manufactured by Yoshii Tekko Co., Ltd. Rex, MI = 7.5g
/ 10 min., Density = 0.917 g / cm ³ ), and bonded to the coating layer side of the base film by the sand lamination method to obtain a gas barrier multilayer laminate. At this time, the thickness of the low density polyethylene layer was 20 μm. This multilayer laminate was evaluated by the test method described above. The results are shown in Table 1.

Example 2 A gas-barrier multilayer laminate was obtained in the same manner as in Example 1, except that the amount of the antifogging agent was changed to 5% by weight. The obtained film was evaluated by the test method described above. The results are shown in Table 1.

Example 3 On one surface of the base film formed in Example 1, vinylbenzylaminosilane (Z-603, manufactured by Dow Corning Co., Ltd.) was used as a siloxane compound.
2) Performed in the same manner as in Example 1 except that a mixed solution of 2 vol% and 8 vol% of vinyltrimethoxysilane (manufactured by Toray Silicone Co., SZ-6300) was hydrolyzed by the method of Example 1 to obtain a coating layer having a thickness of 5 μm. A multilayer laminate was obtained by the method of Example 1. This laminated film was evaluated by the test method described above. The results are shown in Table 1.

(Comparative Example 1) The linear low-density polyethylene, adhesive resin, and EVOH used in Example 1 were replaced with PE / AD /
A multilayer laminate was obtained in the same manner as in Example 1 so as to have a layer configuration of EVOH / AD / PE so that the thickness was 20 μm for PE, 3 μm for AD, and 12 μm for EVOH. This laminate was evaluated by the test method described above. The results are shown in Table 1.

Comparative Example 2 The linear low-density polyethylene used in Example 1 was mixed with a polyglycerin fatty acid ester as an antifogging agent in an amount of 0.5% by weight according to Example 1 (this is referred to as PE / AF). ), PE-AF / AD / EVOH / AD / PE by 65φ3 class 5 layer multilayer T die manufactured by Toshiba Machine
-AF was formed so as to have a layer configuration (the die temperature was 2
10 ° C). At this time, the thickness of each layer was 2 for PE-AF.
0 μm, AD was 3 μm, and EVOH was 12 μm. The obtained film was evaluated by the test method described above. Table 1 shows the results.

Comparative Example 3 The base film obtained in Example 1 was coated with a polyethyleneimine-based anchor coating agent, and a diglycerin fatty acid ester having an HLB of 7.3 was used as an antifogging agent in Example 1. 0.5% by weight of a polyethylene resin (manufactured by Showa Denko KK, Shorex, MI = 5 g / 10 min, density = 0.920 g /
cm ³ ) was formed into a single-layer film (referred to as PE-AF) using a 40φ single-layer T-die molding machine manufactured by Yoshii Iron Works, Ltd., polyethylene resin (Showa Denko, Shorex, MI = 7.5).
g / cm ³ , density 0.917 g / cm ³ , hereinafter PE. ) And extrusion lamination by the sand lamination method.
An antifogging film having a layer configuration of AC / PE / PE-AF was obtained. At this time, the thickness of PE was 20 μm. The obtained laminate was evaluated by the test method described above. Table 1 shows the results.

Comparative Example 4 A single-layer film of a linear low-density polyethylene resin obtained by mixing the anti-fogging agent obtained in Example 1 with the multilayer laminate obtained in Comparative Example 1 was used in Example 1. Sandwich was performed with the low-density polyethylene resin to obtain a new multilayer laminate. At this time, the thickness of the low density polyethylene layer was 20 μm. The newly obtained multilayer laminate was evaluated according to the test method described above. The results are shown in Table 1.

[0037]

[0038]

According to the present invention, the non-ionic surfactant which is an anti-fogging agent from AF-PE moves and penetrates into the gas barrier film in the base film to reduce the gas barrier property,
It adversely affects the adhesive to which the base film is adhered and lowers the interlayer adhesion strength.
-It is based on the finding that the adhesive layer comprising a siloxane compound can effectively prevent the decrease in the antifogging property due to the decrease in the antifogging agent concentration in the PE layer. As a result, the multilayer laminate of the present invention has excellent interlayer adhesive strength, can maintain gas barrier properties and anti-fog performance over a long period of time, has excellent mechanical strength and the like, and is excellent in food packaging materials, pharmaceutical packaging materials, and cosmetics. It is useful as a raw material for packaging materials and containers.

Even if the package does not matter transparency,
Even when an aluminum foil is used as the gas barrier layer, local wetting due to local aggregation of water droplets inside the package can be prevented, so that it is also useful as such a packaging material.

Claims (5)

(57) [Claims] 1. Between (a) a base film having a transparent gas barrier resin layer as a constituent layer and (c) an antifogging layer of a polyolefin containing a nonionic surfactant, at least directly on the base film. (B) A gas-barrier multilayer laminate comprising an adhesive layer (b) made of a polymer of a siloxane compound. 2. A gas barrier resin comprising ethylene-vinyl acetate copolymer saponified resin (EVOH), vinylidene chloride-
The gas barrier multilayer laminate according to claim 1, which is a vinyl chloride copolymer, a vinylidene chloride-methyl acrylate copolymer (PVDC), a polyamide resin, or polyacrylonitrile (PAN). 3. The gas barrier multilayer laminate according to claim 1, wherein the siloxane compound is a hydrolysis-polymer of vinylbenzylaminosilane or vinyltrimethoxysilane. 4. The gas barrier multilayer laminate according to claim 1, wherein the siloxane compound is used as an adhesive layer having a thickness of 2 to 15 μm. 5. The nonionic surfactant is selected from the group consisting of sorbitan fatty acid ester, polyoxyethylene sorbitan aliphatic ester, polyoxyethylene aliphatic ester, polyglycerin fatty acid ester, oxyethylene / oxypropylene block polymer, and polyoxyethylene alkyl. The gas-barrier multilayer laminate according to claim 1, wherein one or a mixture of two or more of ether and polyoxyethylene alkylphenol ether is mixed with the polyolefin resin in a range of 0.05 to 8% by weight.