JP2006159801A - Gas barrier laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas barrier laminate suitable as a material for packaging, which shows stable gas barrier property and humidity-resisting adhesion even when stored for a long time under a high humidity condition and which has higher moisture-proofness than the conventional product. <P>SOLUTION: In the gas barrier laminate having a gas barrier layer containing a silicic acid condensation product provided on one surface of a biaxially oriented polypropylene film, the surface roughness of the film on the gas barrier layer side is Rmax≤300 nm and Rz≤200 nm and that on the opposite side to the gas barrier layer, Rmax of 300-2,000 nm and Rz of 200-1,500 nm. In the gas barrier laminate, the above biaxially oriented polypropylene film has a three-layer structure of a skin layer A, a core layer and a skin layer B, the core layer contains a moisture proofness improving resin, the skin layer B contains a pigment, and the gas barrier layer is provided on the skin layer A side through an anchor layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas barrier laminate suitable as various packaging materials and molding materials.

In packaging materials used for packaging foods and the like, gas barrier properties, particularly oxygen, water vapor, carbon dioxide, and aroma (aroma, flavor) barrier properties are important qualities from the viewpoint of protecting the quality of the contents.
Packaging materials using such barrier materials include confectionery bags, bonito packs, retort pouches, meat packaging such as ham and sausage, seafood packaging, dairy packaging, miso packaging, tea and coffee packaging. It is used in many fields such as carbon dioxide beverage containers, cosmetics, agricultural chemicals and pharmaceutical packaging.
On the other hand, heat such as polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamide resins such as nylon 6 and nylon 66, polystyrene, and ethylene vinyl acetate copolymer Plastic resins are widely used as packaging materials because of their excellent strength, heat resistance, transparency, and the like.
However, when films made of these thermoplastic resins are used as packaging materials, the gas barrier properties are insufficient, so they are laminated with thermoplastic resins having gas barrier properties, aluminum foil, aluminum vapor deposited films, silicon vapor deposited films, etc. The method used as a material is common.

  Examples of the thermoplastic resin having a high gas barrier property include polyvinyl alcohol (hereinafter referred to as PVA), polyethylene vinyl alcohol (EVOH, saponified ethylene-vinyl acetate copolymer), polyalcohol (reduced product of polyketone), and polyvinylidene chloride (PVDC). However, high hydrogen bonding resins that exhibit barrier properties due to hydrogen bonding by hydroxyl groups such as PVA and EVOH have sharp barrier properties at high humidity (for example, 20 ° C. and 80% RH or more). There is a problem that decreases. PVDC is excellent in barrier properties under high humidity conditions, but has a large decrease in barrier properties at high temperatures. Moreover, since PVDC is a chlorinated compound, there is a possibility that problems such as the generation of dioxins may occur during incineration, and the recent situation is to refrain from using it as a packaging material as much as possible due to the increased awareness of global environmental problems. is there.

Further, there is a conventional technique for forming a gas barrier layer with an alkali metal silicate solution. For example, an aqueous liquid composed of an alkali metal silicate solution and a coupling agent is applied to the surface of a polymer molded article to form a thin film to obtain a gas barrier laminate (Patent Document 1), an aqueous solution of sodium silicate and silicic acid A method for mixing a lithium aqueous solution and obtaining a coating composition from this mixture (Patent Document 2), and further applying a liquid composition containing water glass and a water-soluble polymer having a plurality of acidic functional groups to form a gas barrier property (Patent Document 3).
All of these have the advantage that the gas barrier laminate can be produced at low cost without performing operations such as vapor deposition, but the gas barrier properties are still insufficient, and the problems of poor coating strength and water resistance remain. .
Patent Document 4 discloses a gas barrier coating mainly comprising an alkali metal polysilicate (silica condensate of alkali metal silicate) and a water-soluble polymer or nitrogen compound on at least one surface of a biaxially stretched polyolefin film having a multilayer structure. A technique for obtaining a gas barrier laminate by coating a metal is disclosed. However, the multi-layer structure of the base material in this method is a technique of laminating inexpensive polypropylene on one side or both sides of a highly permeable cyclic olefin copolymer layer, and the structure, physical properties and gas barrier properties of the base material are completely considered. Absent. As for the gas barrier property, no special measures are taken for the change with time, the whiteness phenomenon, the crack resistance, and the moisture resistance adhesion when exposed to a high humidity environment for a long time. Patent Document 4 discloses a technique for providing a gas barrier layer containing an alkali metal polysilicate and a water-soluble polymer or nitrogen compound, but has insufficient moisture-resistant gas barrier properties, white flower, crack resistance, and moisture-resistant adhesion. It is. A technique for providing an anchor layer made of an acrylic resin and an isocyanate compound is also disclosed, but it does not solve the above problem.

Patent Document 5 discloses a technology relating to a gas barrier film in which a primer layer made of colloidal silica and a water-based polyurethane resin, and a gas barrier layer made of a metal polysilicate and a water-soluble polymer are sequentially laminated on a substrate surface made of a polyolefin-based resin or the like. Is disclosed. However, even in this technique, an anchor layer (primer layer) is used only for an aqueous polyurethane resin, which is a general anchor agent, and the moisture resistance in a high humidity environment is similar to Patent Document 4. And other problems such as white flower have not been solved.
In Patent Document 6, an anchor coat layer made of an organic polymer having a urethane bond or urea bond and a gas barrier layer mainly composed of an alkali metal polysilicate are formed on the surface of a base material made of a polyolefin resin or the like. Sequentially laminated gas barrier films have been proposed. However, this method also uses a conventionally known technique in which the anchor coat layer is simply cross-linked to increase the strength of the film. Similarly to Patent Document 4, a gas barrier layer (condensate layer of alkali metal silicate) Problems such as moisture resistance and white flower due to the degree of condensation of the water cannot be solved.

In Patent Document 7, a gas barrier layer mainly composed of an alkali metal polysilicate, a nitrogen compound, and a water-soluble polymer is laminated on one side of a base material, and a metal alkoxide, a silane coupling agent, or the like is mainly contained in the gas barrier layer. A technique for providing a protective layer is disclosed. The protective layer is an attempt to prevent deterioration of gas barrier properties and decrease in adhesion strength due to exposure under high humidity conditions. As is clear from the results of oxygen permeability in Examples, the protective layer has some effect. Although it is recognized, the gas barrier property is greatly deteriorated by exposure to a high humidity environment. If the exposure is further performed for a long time, not only the gas barrier property is further deteriorated but also the adhesiveness is lowered.
In Patent Document 8, an anchor coat layer mainly composed of a silica sol such as an organic solvent-modified colloidal silica or a hydrolyzate of a silane coupling agent and a gas barrier layer containing an alkali metal polysilicate are sequentially laminated on one surface of a base material. Techniques relating to the laminated film made are disclosed. In the present invention, by adopting an organically modified silica sol film having strong water resistance for the anchor coat layer, the anchor layer is not dissolved by the barrier paint when the aqueous barrier paint is applied. Although it is described that it can be applied uniformly and exhibits good barrier properties, it has not yet prevented moisture resistance deterioration under high humidity conditions.
Patent Document 9 discloses a technique of sequentially laminating an anchor coat layer mainly composed of a polyvinyl acetal resin and an isocyanate compound and a gas barrier layer containing an alkali metal polysilicate on one surface of a base material. Similar to Document 8, it is described that the barrier layer can be applied uniformly and exhibits good barrier properties, but has not yet prevented moisture resistance deterioration under high humidity conditions.

In Patent Document 10, an anchor coat layer containing an organic polymer having a urethane bond or a urea bond, a gas barrier layer mainly composed of an alkali metal polysilicate, an organic polymer having a urethane bond or a urea bond on one surface of a substrate. And a technique of sequentially laminating an overcoat layer containing an organic polymer having both a urethane bond and a urea bond. Although the overcoat layer is provided for the purpose of preventing deterioration of the barrier layer due to thermal damage during melt lamination, it cannot prevent deterioration under a long-term high-humidity environment.
Patent Document 11 discloses a gas barrier layer based on a polyolefin having a surface roughness satisfying any one of the maximum height representing surface roughness: Ry <1.40 μm, 10-point average roughness Rz <0.80 μm. Although the technique regarding the laminated film which has is disclosed, it is only described that a gas barrier layer will become uniform and gas barrier property will become favorable when a base material is smooth.

Patent Document 12 discloses a technique in which a heat seal layer is provided on the outermost layer of a laminate having a gas barrier layer mainly composed of alkali metal polysilicate on one side of a substrate. Quality degradation during long-term storage in the environment is not considered at all, and cannot be used as an actual product.
In Patent Document 13, in a laminate having a gas barrier layer mainly composed of an alkali metal polysilicate on one side of a substrate, the intensity of fluorescent X-rays per unit area of the gas barrier layer is 2 kcps or more and 10 kcps or less for Si element. Techniques relating to certain laminates are disclosed. However, no consideration has been given to moisture adhesion and quality degradation during long-term storage in a high-humidity environment.

In Patent Document 14, an anchor coat layer made of an organic polymer having a urethane bond or a urea bond, a gas barrier layer mainly composed of an alkali metal polysilicate, and an organic polymer with excellent moisture resistance are provided on the surface of the substrate. There has been proposed a gas barrier film in which overcoat layers made of the above are sequentially laminated. However, this technology is a technology that physically protects the gas barrier layer from being damaged by a subsequent process such as laminating with an overcoat, and is completely considered for moisture resistance adhesion and quality deterioration during long-term storage in a high humidity environment. Not.
In Patent Document 15, an anchor coat layer made of an organic polymer having an isocyanate compound, a urethane bond or a urea bond, a gas barrier layer mainly composed of alkali metal polysilicate, a water-soluble polymer or a water-soluble polymer A gas barrier laminate obtained by sequentially laminating an overcoat layer mainly composed of molecules and an inorganic stratiform compound is disclosed. The purpose of this technique is to improve the durability against bending (Gelboflex test) by providing an overcoat layer having gas barrier properties, but the effect is small as apparent from the examples. I do not get. In addition, no consideration is given to moisture resistance adhesion and quality deterioration during long-term storage in a high humidity environment.

Patent Document 16 proposes an attempt to impart water resistance and crack resistance by introducing an organosilicon compound into an alkali metal polysilicate on a substrate that has been surface-modified by a method such as corona discharge or plasma treatment. Has been. In this patent document, by introducing an organic component derived from an organosilicon compound, the shrinkage of the film due to dehydration and condensation during drying that occurs during the formation of the inorganic oxide film is reduced, and a uniform film without cracks is formed. It is possible to obtain a highly flexible film that can withstand stress such as, and it has a hydrolyzable alkoxysilane terminal so that it can be uniformly dispersed and compatible without phase separation from alkali metal polysilicate. The amount of organic components introduced can be increased, and the water resistance due to adhesion between different components (strength deterioration due to moisture permeating the organic / inorganic component interface and prevention of coating cracks) There is a description that can be improved. However, as is clear from the examples, the oxygen permeability increased 20 times or more (the barrier property deteriorated) in a short period of 40 ° C. and 90% for 3 days, and the barrier property deteriorated under high humidity conditions. Has not been prevented.
Patent Document 17 proposes a technique of providing a base material with a vapor deposition layer made of an inorganic oxide on the surface of a gas barrier layer mainly composed of an alkali metal polysilicate. An inorganic oxide is formed on a film having poor moisture resistance. Even if an object vapor deposition layer is provided, the moisture resistance is not sufficiently improved.

Patent Document 18 discloses a film substrate made of a modified polyolefin to which a rosin introduced with a hydroxyl group is added, an anchor layer having excellent alkali resistance, a gas barrier layer mainly composed of alkali metal polysilicate, and an overcoat having excellent alkali resistance. A laminate in which a layer and a sealant layer are sequentially laminated is disclosed. It is a technology that attempts to improve the wettability of the surface of the substrate by adding a compound having a hydrophilic group to the substrate and to improve the adhesion to the anchor layer, and certainly adheres in a low humidity state (23 ° C., 50%). However, when stored at a high humidity, there is a problem that the rosin introduced with a hydroxyl group absorbs moisture and moisture permeates into the anchor layer and the substrate surface, resulting in a significant decrease in adhesion.
As described above, there are many attempts to produce a gas barrier laminate using an alkali metal silicate, but the oxygen barrier property, barrier property deterioration, and adhesion deterioration under high humidity conditions caused by the alkali metal silicate. At present, no solution technology has yet been found.

The present inventors have developed a technique for producing a gas barrier laminate by applying an alkali silicate aqueous solution to a substrate and drying it to form an alkali silicate condensation film.
In Patent Document 19, the outermost layer on at least one side of the support is a layer made of at least one resin selected from polyester resins, polyamide resins, and polycarbonate resins, and the support has a polyolefin resin layer, A gas barrier laminate in which a gas barrier layer containing a silicic acid condensate is provided on the outermost layer surface is disclosed. Although it is a technique for improving the adhesion of the gas barrier layer to the substrate, there is a problem that the moisture barrier resistance, moisture adhesion resistance and crack resistance of the gas barrier layer are insufficient.
In Patent Document 20, as a technique for improving crack resistance, the present inventors have proposed a laminate in which a gas barrier layer includes a silicic acid condensate such as an alkali metal silicate and a flat pigment. Although this technique improves the crack resistance of a gas barrier layer with a flat pigment, there exists a subject that moisture resistance barrier property and moisture-proof adhesion are inadequate.

Patent Document 21 proposes a laminate comprising a polypropylene-based film support made of a resin and a flat pigment as a first gas barrier layer, and a second gas barrier layer made of a silicic acid condensate and an inorganic compound. Improves barrier properties. However, it is difficult to say that the barrier property and moisture resistance in a high humidity state are sufficient.
Patent Document 22 proposes a laminate in which a gas barrier layer containing a silicic acid condensate and magnesium hydroxide fine particles is laminated on at least one side of a support, but still has insufficient moisture barrier properties and moisture resistance adhesion. It is.
Patent Document 23 proposes a laminate having a gas barrier layer containing a silicic acid condensate such as an alkali metal silicate, a nitrogen-containing compound, and a flat pigment in order to improve moisture resistance barrier properties. The present technology has found that the moisture resistance barrier property and moisture resistance adhesion are greatly improved, but the moisture resistance barrier property and moisture resistance adhesion when exposed to high humidity conditions for a long time are insufficient.

In Patent Document 24, the present inventors have proposed a laminate having a gas barrier layer containing an alkali metal silicate, a hydrolysis condensate of a metal alkoxide, a nitrogen-containing compound, and a flat pigment in order to improve moisture resistance barrier properties. Yes. However, the moisture barrier property and moisture adhesion when exposed to high humidity conditions for a long time are insufficient.
In Patent Document 25, a first layer containing a nitrogen-containing compound such as polyalkyleneimine, a second layer containing a silicic acid condensate such as an alkali metal silicate and a flat pigment, and a third layer containing a high hydrogen bonding resin are disclosed. The present inventors have proposed a laminate having these layers. In this technology, the silanol group contained in the second layer containing the silicic acid condensate and the functional group of the high hydrogen bonding resin contained in the third layer form ionic bonds or covalent bonds to form a strong film and resist This is a technology that greatly improves the whiteness resistance under bending and high humidity conditions. Although the technology of the present invention has made it possible to provide a gas barrier laminate that can withstand use under high humidity conditions, moisture barrier resistance and moisture resistance adhesion under further high humidity conditions have been demanded.
In Patent Document 26, a first gas barrier layer layer containing a high hydrogen bonding resin and a nitrogen-containing compound, and a second gas barrier layer containing a silicic acid condensate, a flat pigment, and boron are sequentially laminated on a support. The formed laminate has been proposed by the present inventors. The technology of the present invention has succeeded in greatly improving the moisture resistance barrier and moisture resistance adhesion by causing the first gas barrier layer and the second gas barrier layer to react with each other and to have the inclined structures. However, there has been a demand for moisture barrier resistance and moisture adhesion under further high humidity conditions.

In Patent Document 27, the present inventors have proposed a laminate having a gas barrier layer containing a silicic acid condensate such as an alkali metal silicate, a flat pigment, and a neutralized salt formed of an acidic substance other than silicic acid. The present invention neutralizes an excess alkali metal salt contained in an alkali metal silicate salt with an acidic substance, so that the gas barrier laminate is left to stand for a long time (72 hours) under high humidity conditions, and has white and white resistance. This is a technology that greatly improves However, there has been a demand for moisture barrier resistance and moisture adhesion under further high humidity conditions.
Patent Document 28 discloses a laminate in which a first gas barrier layer containing a silicic acid condensate such as an alkali metal silicate and a second gas barrier layer containing a high hydrogen bonding resin and an acidic substance are sequentially laminated on a support. Proposed. Although the moisture resistance barrier property is greatly improved by the present invention. There has been a demand for moisture barrier resistance and moisture adhesion under further high humidity conditions.
In Patent Document 29, the present inventors have proposed a laminate having a gas barrier layer composed of a silicic acid condensate such as an alkali metal silicate and a flat pigment, and an overcoat layer containing a hydrophobic resin formed thereon. Yes. Although the hydrophobic resin of the overcoat can improve the moisture resistance adhesion of the laminate, moisture resistance barrier resistance and moisture resistance adhesion under further high humidity conditions have been demanded.
Patent Document 30 describes a packaging material with improved water vapor barrier properties and oxygen barrier properties using a laminated polypropylene resin as a base material, but still has sufficient moisture resistance barrier and moisture resistance adhesion under high humidity conditions. It wasn't.

JP-A-8-238711 JP-A-7-18202 JP 05-295299 A JP 2001-071425 A JP 2001-096676 A JP 2001-129915 A JP 2001-162716 A JP 2001-301082 A JP 2002-011824 A JP 2002-0667214 A JP 2002-113826 A JP 2002-283482 A JP 2002-307599 A JP 2002-307601 A Japanese Patent Laid-Open No. 2002-316381 JP 2002-316382 A JP 2003-001745 A JP 2003-020368 A JP 2001-191444 A JP 2001-199016 A JP 2001-212917 A JP 2001-225410 A JP 2001-260264 A JP 2001-270023 A JP 2002-036417 A JP 2002-086610 A JP 2003-071971 A JP 2003-170522 A JP 2003-111578 A JP 2004-17615 A

  The present invention provides a gas barrier laminate that is suitable as a packaging material and exhibits stable gas barrier properties and moisture-resistant adhesion even when stored for a long time under high humidity conditions, and has higher moisture resistance than conventional products. is there.

In order to solve the above problems, the present invention takes the following means.
That is, in the first aspect of the present invention, in the gas barrier laminate in which a gas barrier layer containing a silicic acid condensate is provided on one side of a biaxially stretched polypropylene film, the film has a surface roughness of Rmax 300 nm or less and Rz 200 nm or less on the gas barrier layer side. There is a gas barrier laminate having Rmax 300 to 2000 nm and Rz 200 to 1500 nm on the side opposite to the gas barrier layer.

  In the second aspect of the present invention, the biaxially stretched polypropylene film has a three-layer structure of a skin layer A, a core layer, and a skin layer B. The gas barrier laminate according to the first aspect of the present invention, wherein the gas barrier layer is provided on the skin layer A side via an anchor layer.

  3rd of this invention is a gas barrier laminated body as described in 2nd of this invention whose pigment is an organic pigment.

  4th of this invention is the gas barrier laminated body in any one of 1st-3rd this invention which provided the overcoat layer containing colloidal silica on a gas barrier layer.

  According to the present invention, it is possible to provide a gas barrier laminate that has an excellent gas barrier property even when it has been in air for a long period of time under high humidity conditions, prevents white bloom, and is suitable as a packaging material. It became.

The present invention is described in detail below.
As a result of repeated examinations of gas barrier laminates using silicic acid condensates, the present inventors have found that the moisture resistance of the substrate and the surface properties of the substrate, particularly the surface properties on the side where the gas barrier layer is laminated, are gas barrier properties and moisture resistance. Has been found to have a significant impact on

In the case of a gas barrier laminate using a silicic acid condensate, the adhesion between the gas barrier layer containing the silicic acid condensate and the biaxially stretched polypropylene film (hereinafter referred to as the OPP film) as a base material, particularly moisture-resistant adhesion, under high humidity conditions It has been clarified that gas barrier properties are greatly affected.
When the moisture resistance of the gas barrier laminate provided on the OPP film has been examined, if the gas barrier laminate is stored under high humidity conditions for a long period of time, the gas barrier property and the adhesion are deteriorated. A detailed examination of the gas barrier laminate stored for a long period of time revealed that the humidity was deteriorated between the OPP / anchor layers or inside the anchor layers.
Therefore, the inventors of the present invention have studied the moisture resistance while paying attention to the substrate, and it has been found that the nanometer-order unevenness of the substrate greatly affects the moisture resistance barrier property and the moisture resistance adhesion.
OPP film is added with anti-blocking agents such as silica, zeolite, calcium carbonate, talc, mica, stearic acid compounds, plastic pigments to prevent blocking, improve the appearance of wound products (prevent rolling) and control slipperiness. The surface is uneven. When a gas barrier laminate is produced by applying a barrier layer to such an OPP film, the gas barrier laminate surface of the OPP film is made as smooth as possible to increase the effective thickness of the gas barrier layer or eliminate the defects of the layer. Improvements in gas barrier properties and cost reduction are being carried out.

However, the conventional smoothing is a level said to be “sufficiently smooth” if the surface roughness is on the order of 300 nm to 1000 nm (submicron region) as described in the prior document (Patent Document 11).
However, when the present inventors examined, gas barrier property and adhesiveness under dry conditions have been achieved with the above-mentioned smoothness of 300 to 1000 nm, but the smoothness is 300 nm or less, preferably 200 nm or less, It has been found that when the level is more preferably 150 nm or less, the performance under high humidity conditions, that is, moisture adhesion and moisture barrier properties are remarkably improved.

Hereinafter, the surface roughness of the biaxially stretched polypropylene film of the present invention will be described in detail.
The surface roughness of the OPP film, which is the base material used in the present invention, on the gas barrier layer side (hereinafter referred to as the front side) is Rmax 300 nm or less, and Rz is 200 nm or less. More preferably, Rmax is 250 nm or less and Rz is 150 nm or less.
The surface roughness opposite to the gas barrier layer (hereinafter referred to as the back surface) is Rmax of 300 to 2000 nm and Rz of 200 nm to 1500 nm. More preferably, Rmax is 400 nm to 1500 nm, Rz is 300 nm to 1250 nm, most preferably Rmax is 500 nm to 1250 nm, and the surface roughness Rz is 400 nm to 1000 nm.

When the surface roughness Rmax of the front surface exceeds 300 nm or Rz exceeds 200 nm, the moisture resistance barrier property and the moisture resistance adhesion are deteriorated.
Further, when the surface roughness Rmax of the back surface exceeds 2000 nm or Rz exceeds 1500 nm, the unevenness of the back surface is transferred to the front surface when the OPP film is wound, and as a result, the front surface Smoothness decreases. Moreover, after manufacturing a gas barrier laminated body, since a gas barrier layer is damaged by the unevenness | corrugation of a back surface, gas barrier property falls.
In addition, when the surface roughness of the back surface is Rmax less than 300 nm or Rz is less than 200 nm, blocking occurs or the winding of the gas barrier laminate is displaced.

The surface roughness is a value measured by a method in accordance with JIS B0610, and the surface roughness Rmax is the maximum height of a portion from which the reference length is extracted, and peaks and valleys that are clearly regarded as flaws. The distance between the highest peak and the deepest valley, that is, the maximum unevenness difference on the substrate surface is shown.
Further, the surface roughness Rz is an average height of 10 points, and the average value of the altitude of the highest mountain peak from the highest part of the portion where the reference length is extracted and the average value of the altitude of the valley bottom from the deepest to the fifth. The difference value is shown.
Rmax and Rz in the present invention are values measured with an atomic force microscope capable of measuring nano-order unevenness.
An example of the atomic force microscope is NANOPICS1000 manufactured by Seiko Instruments Inc.

The present inventors consider as follows the mechanism by which the moisture resistance of the gas barrier layer is dramatically improved by controlling the surface smoothness of the film substrate to the nano-order level.
That is, since the base material has nano-order level smoothness, when an anchor layer or gas barrier layer coating is applied, the anchor layer or barrier layer follows the irregularities on the nano-order level and is very uniform and strong. It is thought that a film is formed. In addition, since the unevenness is nano-order, the number of unevenness becomes very large, and the "throwing effect" in so-called adhesion science has become very large, resulting in improved adhesion between the base material and the anchor layer, particularly moisture-resistant adhesion .
In addition, the anchor layer absorbs moisture and swells, thereby reducing the adhesion and barrier properties of the anchor layer. It is thought that moisture is trapped in the anchor layer and the anchor layer is difficult to swell.
When an OPP film is provided with a coating layer made of an aqueous coating solution, surface treatment such as corona treatment or plasma treatment is usually performed so that hydrophilic functional groups such as carboxylic acid groups, carbonyl groups, and hydroxyl groups are exposed on the surface. However, when the unevenness of the surface is large, discharge such as corona treatment or plasma treatment occurs only on the convex portion where the electric charge is concentrated, so that the functional group is formed only on the convex portion. For this reason, the reaction and bonding with the gas barrier layer or anchor layer to be coated thereon become non-uniform, and the moisture-resistant adhesion and moisture-resistant barrier properties are lowered. However, if the unevenness on the surface of the film is at the nano-order level, the surface is treated uniformly, so that the reaction and bonding between the functional groups on the film surface and the coating layer become uniform. It is thought that a construction layer is formed.

The polypropylene resin that can be used for the OPP film as the base material in the present invention is preferably an isotactic polypropylene resin (homopolypropylene), an ethylene-modified isotactic polypropylene resin (random copolymer or block copolymer), a metallocene polypropylene resin, or the like. it can. Also, atactic polypropylene and syndiotactic polypropyne can be used. Further, two or more kinds of these polypropylenes can be mixed and used.
Among these resins, isotactic polypropylene resin (homopolypropylene) can be most suitably used in terms of smoothness and moisture resistance. Since isotactic polypropylene has high crystallinity, the molecular chains are packed tightly so that it has excellent moisture resistance, and since its thermal shrinkage rate is low, it can be stretched uniformly during stretching, resulting in smoothness. Further, when an amorphous component such as atactic polypropylene is increased, atactic polypropylene is precipitated on the surface at the time of stretching, and the surface property is lowered.

  The melt flow rate (hereinafter referred to as MFR) at 210 ° C. of the polypropylene resin used in the present invention is preferably 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / min, most preferably 1 to 10 g. / 10 min. When the MFR is less than 0.1 g / 10 min, it is difficult to produce a biaxially stretched OPP film. When the MFR exceeds 100 g / 10 min, the heat resistance is reduced, and the heat shrinkage becomes severe due to the heat of coating drying when forming the gas barrier layer. It becomes difficult to form a uniform gas barrier layer.

The n-heptane index (= n-heptane extraction residue, hereinafter HI) of the polypropylene resin used in the present invention is preferably 94.0 to 99.9%, more preferably 95.0 to 99.5%. Most preferably, it is 96.0 to 99.0%.
When the HI is less than 94.0%, the smoothness of the surface of the obtained polypropylene film is lowered, and as a result, the moisture barrier property of the gas barrier layer is lowered, which is not preferable. On the other hand, if the HI is larger than 99.9%, problems such as breakage occur in the stretching process during the production of the OPP film, which is not preferable.
The molecular weight of the polypropylene resin is preferably 400,000 to 700,000 in terms of mass average molecular weight, more preferably 450,000 to 650,000, and still more preferably 500,000 to 600,000. The sum average molecular weight is preferably 80,000 to 140,000, more preferably 90,000 to 130,000, and still more preferably 100,000 to 120,000. If the molecular weight is too small (mass average molecular weight of less than 400,000 or number average molecular weight of less than 80,000), blocking is likely to occur or moisture resistance is lowered, which is not preferable. On the other hand, if the molecular weight is too large (the mass average molecular weight exceeds 700,000, or the number average molecular weight exceeds 120,000), the stretchability at the time of forming the OPP film is deteriorated, and the smoothness of the OPP film surface is deteriorated. This is not preferable because the moisture-resistant gas barrier property is lowered.
Further, the ratio Mw / Mn of the mass average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 3.0 to 6.0.

In addition, the OPP film in this invention can contain well-known additives normally used, such as antioxidant, as needed.
Antioxidants that can be used include hindered phenol compounds, phenol compounds, phosphorus processing stabilizers, phosphorus antioxidants, and the like. As a hindered phenol type, Irganox 1010 (compound name: pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], melting point 110-125 °) manufactured by Ciba Geigy, phenol type BHT (2,6-di-t-butyl-4-methylphenol, melting point 69 ° C.) as a compound, Irgafos 168 (Tris (2,4-di-t-butylphenyl) manufactured by Ciba Geigy as a phosphorus processing stabilizer Examples of phosphite, melting point 183 to 186 ° C.) and phosphorus antioxidant include ADK STAB HP-10 manufactured by Asahi Denka.
In the present invention, the thickness of the OPP film used is preferably 5 to 100 μm, more preferably 10 to 80 μm, and further preferably 15 to 60 μm.

In order to further improve the moisture resistance of the gas barrier laminate, the present inventors studied to add a moisture resistance improving resin such as petroleum resin to the polypropylene resin to the OPP film as the base material. In addition to improving the moisture resistance, the intrusion of moisture into the anchor layer was prevented, and the moisture resistance of the gas barrier laminate (gas barrier layer) was also improved.
However, when an anchor layer is provided on the surface of an OPP film made of a polypropylene resin containing a moisture-proof improving resin, the moisture-proof improving resin inhibits the adhesion between the anchor layer and the OPP film, so that the moisture resistance of the anchor layer is lowered. In addition, it is difficult to uniformly form the anchor layer, and the gas barrier property may be lowered.
Therefore, the layer made of the polypropylene resin containing the moisture proof improving resin is used as the core layer of the OPP film, and the polypropylene layer not containing the moisture proof improving resin is provided as the skin layer A on the side of the front side of the OPP film. It was found that when an anchor layer and a gas barrier layer were provided on the skin layer A in such a manner that the property improving resin was not deposited, a gas barrier laminate having excellent moisture gas barrier resistance and moisture resistance adhesion was obtained.
Further, it is desirable to provide a skin layer B that does not contain the moisture-proof improving resin on the back surface of the OPP film in order to prevent bleeding out of the moisture-proof improving resin. When the moisture proof improving resin bleeds out (deposits) on the back side, when the biaxially stretched OPP film is wound up, the petroleum resin is transferred to the skin layer A, and the surface roughness of the skin layer A becomes large. It is not preferable because the forming coating is repelled, the coating layer becomes uneven, the moisture resistance is lowered, and the adhesion is lowered.

In addition, as a moisture-proof improvement resin used for the core layer of this invention, petroleum resin, terpene resin, rosin resin, hydrogenated rosin resin, etc. are mentioned.
Petroleum resin refers to those obtained by polymerizing an aromatic hydrocarbon having a polymerizable double bond in the side chain of a petroleum fraction as a main component. As a polymerizable aromatic hydrocarbon, specifically, , Styrene, α-methylstyrene, vinyltoluene, vinylxylene, propenylbenzene, indene, methylindene, ethylindene, coumarone and the like. Petroleum resins include aromatic hydrocarbons having a polymerizable double bond as well as olefins such as butene, pentene, hexene, heptene, octene, butadiene, pentadiene, cyclopentadiene, dicyclopentadiene, octadiene and the like. Or what is obtained by superposing | polymerizing 2 or more types is also included. Furthermore, petroleum resins include those obtained by thermal polymerization of cyclopentadiene or dicyclopentadiene.
Terpene resins are sometimes called terpenoids, and typical compounds include pinene, dipentene, karen, myrcene, oschimen, limonene, terpinolene, terpinene, sabinene, tricyclene, bisabolen, gingipeperene, santalen. Terpene resins obtained by cationic polymerization of α-pinene, β-pinene, dipentene, etc. using Friedel-Crafts catalysts such as aluminum chloride and boron trifluoride have improved moisture resistance. This is preferable. Alternatively, a copolymer composed of these terpene fractions and styrenes may be used.
The petroleum resin or terpene resin is preferably hydrogenated because the odor of the petroleum resin or terpene resin is eliminated and the heat resistance is excellent. The hydrogenation rate is preferably 90% or more, and more preferably 95% or more.
Further, the petroleum resin is a petroleum resin having no polar group composed of a hydroxyl group, a carboxyl group, a halogen group, a sulfone group, and a modified product thereof, that is, a cyclopentadiene series directly using a petroleum unsaturated hydrocarbon, or Resins mainly composed of higher olefinic hydrocarbons are more preferred because they are excellent in moisture proofing.
Further, the glass transition temperature (hereinafter abbreviated as Tg) of the petroleum resin is preferably 60 ° C. or higher. If Tg is less than 60 ° C., the effect of improving moisture resistance is small.
As the most preferable hydrogenated petroleum resin, for example, a high Tg fully hydrogenated alicyclic petroleum resin such as polydicyclopentadiene having a Tg of 70 ° C. or more and a hydrogenation rate of 99% or more can be mentioned.
The terpene resin is a terpene resin having no polar group composed of a hydroxyl group, an aldehyde group, a ketone group, a carboxyl group, a halogen group, a sulfone group, and a modified product thereof, that is, a carbonized composition having a composition of (C ₅ H ₈ ) n. Hydrogen and a modified compound derived therefrom are preferable because of their excellent effect of improving moisture resistance.

  As a compounding quantity of the said moisture-proof improvement resin, 1-100 mass parts is preferable with respect to 100 mass parts of polypropylene resins, More preferably, it is 5-75 mass parts, More preferably, it is 10-50 mass parts. When the blending amount of the moisture-proof improving resin is less than 1 part by mass, the moisture-proof improving effect is insufficient. On the other hand, if it exceeds 100 parts by mass, the stretchability is lowered, and the production of the biaxially stretched OPP film becomes difficult, which is not preferable.

The polypropylene resin used for the core layer of the present invention is preferably a highly stereoregular resin. In the present invention, a highly stereoregular resin refers to a resin having a content of isotactic polypropylene resin of 90% or more. Preferably, 93% or more, more preferably 95% or more is used.
Alternatively, an ethylene-polypropylene copolymer having an ethylene mass ratio of 5% or less, preferably 3% or less, more preferably 1% or less can be suitably used. If the ethylene polymerization ratio exceeds 5%, the moisture-proof property is lowered, which is not preferable.

  The polypropylene resin used for the core layer preferably has a HI of 96.0% to 99.0% from the viewpoint of moisture resistance. If the HI is less than 96%, the moisture resistance and heat resistance are inferior, which is not preferable. If the HI exceeds 99%, the stretchability is deteriorated, which is not preferable.

99.50-99.99 mass% is suitable for the ratio of the polypropylene resin contained in the skin layer A in this invention, 99.60-99.97 mass% is more preferable, and 99.70-99.95 mass is preferable. % Is more preferable. When the proportion of the polypropylene resin is less than 99.50%, the moisture-resistant gas barrier property and the moisture-resistant adhesion are deteriorated, which is not preferable. Moreover, when the ratio of a polypropylene resin exceeds 99.99 mass%, since the stability at the time of OPP film manufacture will worsen, it is unpreferable.
The content of the antioxidant contained in the skin layer A is preferably 100 to 10,000 ppm. More preferably, it is 200-5000 ppm, More preferably, it is 300-2500 ppm. When the content of the antioxidant is less than 100 ppm, the oxidative degradation of polypropylene is severe, which is not preferable because the productivity during the production of the OPP film is lowered. On the other hand, when the content of the antioxidant exceeds 10,000 ppm, the surface property of the skin layer A is deteriorated or the adhesion between the anchor layer and the skin layer A is unfavorable.

In addition, when the present inventors manufacture such a gas barrier laminate and make it into a wound product, the gas barrier layer surface and the back surface of the gas barrier laminate may cause blocking, or the winding end face may become uneven. May occur.
In order to solve the above problem, by providing a skin layer B with a layer containing a pigment as an anti-blocking agent on the back surface of the OPP film, a gas barrier laminate having excellent blocking resistance and excellent winding appearance. Can be able to provide.

Although there is no restriction | limiting in particular as a pigment which can be used as an antiblocking agent in the said invention, It is preferable that it is a pigment with a particle diameter of 0.1 micrometer-10 micrometers.
Specific examples include inorganic particles such as silica particles, alumina, (synthetic) zeolite, calcium carbonate, kaolin, talc, mica, zinc oxide, magnesium oxide, quartz, magnesium carbonate, parium sulfate, titanium dioxide, polystyrene, polyacryl Particles, polymethyl methacrylate (PMMA) particles, crosslinked polyethylene particles, polyester, polyamide, polycarbonate, polyether, polyethersulfone, polyetherimide, polyphenylene sulfide, polyetheretherketone, polyamideimide, (crosslinked) melamine resin, Benzoguanamine resin, urea resin, amino resin, furan resin, epoxy resin, phenol resin, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, polyimide resin, etc. Pigments and the like. Among these, PMMA and silica particles are preferably used because they are excellent in blocking resistance and slipperiness.
In addition, since the organic pigment is soft and does not easily fall off from the resin layer, when the OPP film is produced and wound, the pigment is transferred and adhered to the front surface on the opposite side, causing surface defects. Further, it is particularly preferable because there is no fear of damaging the surface. Among organic pigments, polyacrylic particles are particularly preferable, and among them, polymethyl methacrylate (PMMA) is preferable in terms of blocking resistance.

  The content of the pigment in the skin layer B is preferably 300 to 5000 ppm, more preferably 400 to 4000 ppm, still more preferably 500 to 3000 ppm with respect to the polypropylene resin. When the pigment content is less than 300 ppm, the effect of blocking resistance is poor, and when it is 4000 ppm or more, the effect of blocking resistance reaches its peak, the surface smoothness of the skin layer A is lowered, and the gas barrier laminate The gas barrier layer may be damaged and the gas barrier property may be lowered.

  In the present invention, the skin layer A may also contain a pigment as an anti-blocking agent as necessary, but the content is preferably 200 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less. When the pigment exceeds 200 ppmm, the smoothness of the skin layer A is lowered, and the moisture-resistant gas barrier property and moisture-resistant adhesiveness are lowered.

In the present invention, the thickness of the skin layer A is preferably 0.5 to 40%, more preferably 1 to 30%, still more preferably 2 to 25% with respect to the thickness of the OPP film. If the skin layer A is thinner than 0.1%, the surface smoothness of the skin layer A is lowered, and the moisture resistance barrier property and moisture resistance adhesion property are lowered. If the thickness of the skin layer A exceeds 40%, the moisture resistance decreases, which is not preferable.
Further, the thickness of the core layer is preferably 20 to 99%, more preferably 40 to 98%, still more preferably 50 to 96% with respect to the thickness of the OPP film. When the thickness of the core layer is less than 20%, the effect of improving the moisture resistance is small, and when it exceeds 99%, the moisture-resistant gas barrier property and the moisture-resistant adhesion are deteriorated.
Further, the thickness of the skin layer B is preferably 0.5 to 40%, more preferably 1 to 30%, and further preferably 2 to 25% with respect to the thickness of the OPP film. If the thickness of the skin layer B is less than 0.1%, the effect of moisture-proof blocking is very small. If the thickness of the skin layer B exceeds 40%, the moisture-proof property is lowered, which is not preferable.

The silicic acid condensate used for the gas barrier layer of the present invention contains at least one kind of silicic acid condensate selected from alkali metal silicates or colloidal silica.
Among the silicic acid condensates, the alkali metal silicate is a compound represented by M ₂ O.nSiO ₂ (M is an alkali metal, n> 0). It is usually handled as a concentrated aqueous solution.
The alkali metal M is lithium, sodium, potassium or the like. In the present invention, a cationic ion such as ammonium is also included in the category of M. n is also called a molar ratio, and a range of about 0.5 to 10 is preferable. If the molar ratio is less than 0.5, the film-forming ability due to the condensation of silicic acid is lowered, or the content of alkali metal salt is too much, so the water resistance and moisture resistance are often lowered, and the white flower phenomenon tends to occur. On the other hand, when the molar ratio exceeds 10, there may be a problem in the coated surface such as the occurrence of cracks.

  Note that alkali metal silicates having a high molar ratio exceeding 10 are generally not commercially available, but a method of adding various alkali metal hydroxides to amorphous silica or colloidal silica and dissolving them, or commercially available silicic acid It can be prepared by a method of dissolving amorphous silica or colloidal silica in an alkali metal salt, and the alkali metal silicate prepared in this way can also be used in the present invention. When using alkali metal silicates with a high molar ratio, shrinkage in the thickness direction can be reduced by using very thin flat pigments with a specific shape or by forming ultrathin films of 0.5 μm or less. If the surface shrinkage is almost the same, cracks are less likely to occur.

Of the silicic acid condensates, colloidal silica can be obtained by neutralizing sodium silicate with an inorganic acid or hydrolyzing silicon ester or silicon halide. In addition, after passing an alkali metal silicate such as sodium silicate through the cation ion exchange resin layer, the pH is adjusted with an alkali, and then heated to produce a core of colloidal silica, and the cation exchange resin layer is further passed through the liquid. It is obtained by slowly dropping the sodium silicate solution. When the dropping speed is increased rapidly, the condensation proceeds rapidly, aggregation is generated, and a porous structure is obtained. By slowly dripping, the monomer deposits sequentially on the silanol groups on the surface of the nucleus to grow particles. Colloidal silica can be grown to an arbitrary size of several nm to several μm by adjusting pH appropriately and slowing the dropping rate. The particle diameter of the colloidal silica used in the present invention is preferably in the range of several nm to several hundred nm. Moreover, a filling rate can also be enlarged by using colloidal silica of a different particle diameter in combination.
Colloidal silica may be inferior in film-forming property and gas barrier property as compared with alkali metal silicate. In that case, the film formability and gas barrier properties can be improved by adding an alkali metal salt to the colloidal silica to cleave the siloxane bond on the surface of the colloidal silica.

As the silicic acid condensate used in the present invention, alkali metal silicates and colloidal silica are more preferably alkali metal silicates in view of only gas barrier properties.
Examples of the alkali metal silicate include sodium orthosilicate (Na ₂ O.1 / 2SiO ₂ or Na ₄ SiO ₄ ) having a molar ratio of 0.57 and sesquioxide having a molar ratio of 0.67 when the alkali metal is sodium silicate. sodium silicate _{(3Na 2} O · 2SiO 2 or _Na 6 _Si 2 _O 7), sodium metasilicate molar ratio 1 _{(Na 2} O · SiO 2 or _Na 2 _SiO 3), sodium disilicate molar ratio 2 _(Na 2 O・ 2SiO ₂ or Na ₂ Si ₂ O ₅ ), sodium tetrasilicate with a molar ratio of 4 (Na ₂ O.4SiO ₂ or Na ₂ Si ₄ O ₉ , also known as: sodium silicate No. 4), etc. Sodium silicate No. 1 (molar ratio 2), No. 2 (molar ratio 2.5), No. 3 (molar ratio 3), metasilicic acid defined in JIS-K-1408 One thorium, is sodium metasilicate two.

There are various compositions of potassium silicate in which the alkali metal is potassium, but examples include potassium metasilicate (K ₂ O · SiO ₂ ), potassium tetrasilicate (K ₂ O · 4SiO ₂ · H ₂ O, also known as Potassium dihydrogen silicate). Lithium silicate whose alkali metal is lithium is lithium orthosilicate (Li ₂ O · 1 / 2SiO ₂ ), lithium metasilicate (Li ₂ O · SiO ₂ ), 3.5 lithium silicate, 7.5 lithium silicate (Li ₂ O.7.5SiO ₂ ).
For example, ammonium salts such as ammonium silicate using tetramethylammonium ions as counter ions are also included in the category of alkali metal silicates in the present invention.

These alkali metal silicates have different degrees of condensation and different particle sizes depending on the molar ratio. The size cannot be clearly determined because the solubility in the liquid increases as the molar ratio decreases, but by analogy with the dynamic light scattering method, most of them are several nanometers or less, and as a gas barrier layer Can be packed densely.
These alkali metal silicates may be used as a mixture of two or more as required, or two or more kinds of alkali metal silicates and colloidal silica may be used as a mixture. Further, an alkali metal salt may be added to improve the film formability.

The gas barrier layer of the present invention preferably contains a boron compound for improving the moisture-resistant gas barrier property. Examples of the boron compound include boron oxide, ammonium tetraborate, sodium tetraborate, boric acid, and anhydrous boric acid.
The addition amount of the boron compound is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, and most preferably 1 to 10% by mass with respect to the silicic acid condensate. If the amount of boron compound added is less than 0.1% by mass, the effect of improving the moisture-resistant gas barrier property by adding the boron compound is small, and if it exceeds 20% by mass, the condensation of silicic acid condensate may be inhibited and the gas barrier property may be lowered. There is.

In the present invention, it is preferable to provide an anchor layer between the biaxially stretched polypropylene base material layer and the gas barrier layer from the viewpoint of moisture resistance, moisture resistance adhesion and the like.
The anchor layer in the present invention is preferably an anchor layer containing a nitrogen-containing compound. The reason for this is that the anchor layer is excellent in moisture resistance because the carboxylic acid group, carbonyl group or hydroxyl group-containing anionic functional group of the skin layer A subjected to corona treatment and a cationic nitrogen-containing compound form an ionic bond. Is formed. Furthermore, silicic acid (SiOH) and nitrogen-containing compounds contained in the silicic acid condensate in the gas barrier layer form an ion complex or promote cross-linking of the silicic acid condensate, thereby improving the moisture barrier gas barrier property of the gas barrier layer. .

  Typical nitrogen-containing compounds are those called imine compounds and amine compounds. Among these, as the imine compound, polyalkyleneimine is representative, polyethyleneimine, alkyl or cyclopentyl modified polyethyleneimine, imine adduct of ethylene urea, poly (ethyleneimine-urea) and ethyleneimine adduct of polyamine polyamide, or There are polyimine compounds selected from the group consisting of these alkyl-modified products, alkenyl-modified products, benzyl-modified products, or aliphatic cyclic hydrocarbon-modified products, polyamideimides, and polyimide varnishes.

  Examples of amine compounds include polyalkylene polyamines. For example, there are compounds such as polyethylene polyamine, ethylenediamine, diethylenetriamine, triethylenetetramine. In addition, examples of the same effect include polyamides such as polyamidoimide adducts of polyamides, hydrazine compounds, and epichlorohydrin adducts of polyamine polyamides (saturated dibasic carboxylic acids having 3 to 10 carbon atoms and polyamines). Polyamineamide compounds such as water-soluble and cationic thermosetting resins obtained by reacting polyamides with epichlorohydrin from alkylene polyamines, quaternary nitrogen-containing acrylic polymers, quaternary nitrogen-containing benzyl polymers, urethanes, carboxylate amines There are nitrogen-containing quaternary salt compounds such as compounds having a base, compounds such as methylolated melamine, and cationic polyurethane. Further, cationic resins such as cation-modified polyurethane resin, polyvinyl pyrrolidone, vinyl pyrrolidone-vinyl acetate copolymer, tertiary nitrogen-containing acrylic resin and the like can be mentioned (for cation resin, JP-A-8-90898, JP (Described in JP-A 63-162275, JP-A 62-148292, etc.). Among the nitrogen-containing compounds, polyalkylenimine is most preferable in terms of moisture gas barrier property and moisture adhesion resistance.

  As the polyalkyleneimine, polyethyleneimine and polypropyleneimine are preferable, and in particular, polyethyleneimine is most preferable in terms of moisture resistance. These polyalkyleneimines may be used alone or in the form of a salt with acetic acid, p-toluenesulfonic acid, sulfuric acid, hydrochloric acid or the like.

  The anchor layer of the present invention can contain a highly hydrogen-bonding water-soluble resin, colloidal silica, or a silane coupling agent. In particular, combining the three components of nitrogen-containing compounds, highly hydrogen-bonding water-soluble resins, and colloidal silica improves moisture-resistant gas barrier properties and moisture-resistant adhesion, and nitrogen-containing compounds, highly hydrogen-bonding water-soluble resins, colloidal silica, and silane. When the four components of the coupling agent are combined, the moisture-resistant gas barrier property and moisture-resistant adhesion are further improved.

The high hydrogen bonding resin serves to uniformly form the anchor layer, and further serves as a protective colloid of colloidal silica that prevents aggregation of the colloidal silica and the nitrogen-containing compound. Colloidal silica has the effect of imparting moisture resistance to the anchor layer. In particular, moisture resistance is enhanced by forming a complex in the anchor layer with a water-soluble resin having high hydrogen bonding properties. Furthermore, the coupling agent improves moisture resistance by reacting with the substrate surface, reacting with the silanol group on the colloidal silica surface or the functional group of the high hydrogen bonding resin, and crosslinking.
Examples of the high hydrogen bonding water-soluble resin include polyvinyl alcohol, starch, ethylene-vinyl alcohol copolymer, polyacrylic acid, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and the like. Among these, polyvinyl alcohol can be preferably used from the viewpoint of film formability. Among polyvinyl alcohols, polyvinyl alcohol modified with a silyl group is preferable because of its excellent compatibility with colloidal silica and silane coupling agents.

  As the colloidal silica, those having a particle diameter of 1 to 400 nm can be preferably used. More preferably, a film having a thickness of 2 to 200 nm, most preferably 3 to 100 nm can be used. From the viewpoint of water resistance, ammonia neutralized colloidal silica can be preferably used.

  Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxy. Propyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilanephenyltriethoxysilane, γ-fluoropropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, and the like can be given. Among these, amino group-containing silane coupling agents can be suitably used from the viewpoint of moisture-resistant gas barrier properties and moisture-resistant adhesion.

In the present invention, it is preferable to provide an overcoat layer containing colloidal silica on the gas barrier layer.
The gas barrier laminate of the present invention is a sealant obtained by printing on a gas barrier surface, then laminating with a CPP (non-stretched polypropylene) film or PE (polyethylene) film having excellent heat sealability, and laminating with a PE or PP melt extrusion laminate. After the layer is formed, the contents of foods and the like are packaged, and an overcoat layer can be provided in order to improve moisture adhesion and printability with the sealant layer.
As the colloidal silica contained in the overcoat layer, colloidal silica having a particle diameter of preferably 1 to 400 nm, more preferably 2 to 200 nm, and most preferably 3 to 100 nm can be used. From the viewpoint of water resistance, colloidal silica neutralized with ammonia can be preferably used. Further, the overcoat layer may contain a water-soluble resin having a high hydrogen bonding property that can be used for the anchor layer.

  The transparency of the gas barrier laminate in the present invention is 80% or more, more preferably 85% or more, and the haze is preferably in the range of 0.5 to 10% with a total light transmittance of a wavelength of 500 nm. . Such transparency can be suitably measured with, for example, a commercially available spectrophotometer (Shimadzu autograph spectrophotometer UV-3100PC type: manufactured by Shimadzu Corporation).

The oxygen permeability at 23 ° C. and 90% RH of the gas barrier laminate in the present invention is preferably 5 cc / m ² · day · atm or less after 144 hours from the start of measurement, more preferably 3 cc / m ² · day ·. atm, more preferably 1 cc / m ² · 24 hr or less.
In the present invention, additives such as a color adjusting agent, a viscosity adjusting agent, an inorganic pigment, an organic pigment, a curing agent, and a crosslinking agent are optionally added to each layer of the gas barrier layer, the anchor layer, and the overcoat layer. be able to.

In the gas barrier laminate of the present invention, the surface of the OPP film is subjected to corona treatment, plasma treatment, flame treatment, concentrated sulfuric acid treatment, and ozone gas treatment, and then an aqueous coating to be an anchor layer and gas barrier layer is applied and dried. Obtained.
Coating methods include direct gravure method, reverse gravure method, micro gravure method, roll roll coating method such as two roll beat coating method, bottom feed three reverse coating method, doctor knife method, die coating method, dip coating method, bar Coating methods, kiss coating, lip coating, blade coating, air knife coating, bar coating and the like can be arbitrarily used depending on the situation. Moreover, these coating methods can be used in combination. Moreover, it is not limited to these methods.

Moreover, as a drying method, the drying method using a hot air, dry air, infrared rays, a microwave, a gas burner etc. can be used arbitrarily. Moreover, although the drying method combining these 2 or more types can also be used, it is not limited to these methods.
Although there is no restriction | limiting in particular in drying temperature, Preferably it is 50-180 degreeC, More preferably, it is 60-150 degreeC, Most preferably, it is 70-140 degreeC. When the drying temperature is lower than 50 ° C., the silicic acid condensation reaction of the gas barrier layer may not sufficiently occur. Moreover, when it exceeds 180 degreeC, there exists a possibility that the thermal contraction of the OPP film which is a base material may become intense, and a wrinkle may enter.

Hereinafter, the present invention will be specifically described with reference to examples.
Numerical values indicating the blending, concentration, added amount, etc. are numerical values based on the solid content or the mass of the active ingredient.

<Example 1>
An OPP film is obtained as follows.
Polypropylene resin (trade name F300SP, MFR = 3.0, HI = 96.0, manufactured by Idemitsu Petrochemical Co., Ltd.) was used as the resin for skin layer A.
To 80 parts by mass of polypropylene resin (trade name PL400A, MFR = 2.0, HI = 98.0, manufactured by Sun Allomer), petroleum resin (trade name Alcon P125, manufactured by Arakawa Chemical) and polypropylene resin (PL400A) are 1: 1. A mixture obtained by dry blending 20 parts by mass of a petroleum resin master batch obtained by melt-kneading was used as a resin to be a core layer.
98 parts by mass of a polypropylene resin (F300SP) was dry blended with 2 parts by mass of an organic pigment master batch obtained by dispersing an organic pigment (PMMA powder having an average particle size of 3.0 μm) in a polypropylene resin (F300SP) at a concentration of 20%. The mixture was used as a resin for skin layer B.
The above three types of resins were extruded using a three-type three-layer T-die melt extrusion film forming apparatus. A 1000 μm thick film formed from a T-die was longitudinally stretched 5 times at 145 ° C. by a conventional sequential biaxial stretching apparatus, and then stretched 10 times at 150 ° C. to obtain an OPP film. The thickness of the film was 20 μm (skin layer A = 2 μm, core layer = 16 μm, skin layer C = 2 μm).
Further, the surface roughness Rmax of the skin layer A of this OPP film was 105 nm, and Rz was 86 nm. The surface roughness Rmax of the skin layer B surface was 634 nm, and Rz was 316 nm.

Next, an anchor paint is obtained as follows.
To a solution obtained by adding 12 parts by mass of IPA to 100 parts by mass of water, 5 parts by mass of colloidal silica (trade name Snowtex N, solid content 20%, particle size 15 nm, ammonia neutralization, manufactured by Nissan Chemical), polyvinyl alcohol (trade name PVA) -R1130 (degree of saponification 99%, manufactured by Kuraray Co., Ltd.) 80 parts by mass of a 5% aqueous solution were sequentially added and stirred for 1 hour or more.
Then, polyethyleneimine (trade name Epomin P-1000, solid content 30%, molecular weight 70,000, specific gravity 1.04, amine value 18 (mgeq / g · solid), amine ratio primary / secondary / third grade = 25 11 parts by mass of a 5% aqueous solution of / 50/25, manufactured by Nippon Shokubai Co., Ltd. was added and stirred.
Furthermore, an amino-modified silane coupling agent (trade name KBM903, chemical name 3-aminopropyltrimethoxysilane, chemical formula: (CH ₃ O) ₃ SiCH ₂ CH ₂ CH ₂ NH ₃ , manufactured by Shin-Etsu Chemical Co., Ltd.) is made into a 5% aqueous solution, After stirring for 30 minutes or more and hydrolyzing, 33 parts by mass was added and stirred.
Thereafter, 0.022 parts by mass of acetylene diol (trade name Surfynol 104PA, active ingredient 50%, isopropyl alcohol solution, manufactured by Nissin Chemical Industry) was added to obtain an anchor coating material having a solid content of 3% (pH 10. 5. Dynamic surface tension 45 dyne / cm, static surface tension 41 dyne / cm).
After the corona treatment of the skin layer A surface of the OPP film, the anchor paint is coated with a gravure coater (normal gravure, 180 mesh, coating speed 100 m / min, drying temperature 95 ° C.) 0.12 g / m ² Coating was carried out so that (solid content conversion) was obtained, and an anchor layer was provided on the OPP film.

Next, a gas barrier paint is obtained as follows.
15 parts by mass of lithium silicate (trade name: lithium silicate 35, 23% as solid content Li ₂ O · SiO ₂ , manufactured by Nippon Chemical Industry Co., Ltd.) is added to 100 parts by mass of water. After stirring, boron oxide (B ₂ O ₃ , Wako Pure) After adding 3.4 parts of 3% aqueous solution (made by Yakuhin) and stirring, 0.014 parts by mass of acetylene diol (trade name Surfynol 104PA, active ingredient 50%, isopropyl alcohol solution, manufactured by Nissin Chemical Industry Co., Ltd.) A gas barrier paint having a solid content of 3% was prepared (pH 11.1, dynamic surface tension 55 dyne / cm, static surface tension 50 dyne / cm).
The obtained barrier coating was coated on the anchor layer with a gravure coater (normal gravure, 180 mesh, coating speed 100 m / min, drying temperature 95 ° C.) and a coating amount of 0.12 g / m ² (in terms of solid content) Coating was performed to produce a wound gas barrier laminate.

<Example 2>
To 100 parts by weight of water, 1.8 parts by weight of colloidal silica (Snowtex N) and 10 parts by weight of a 3% aqueous solution of silyl-modified polyvinyl alcohol (trade name PVA-R2105, saponification degree 88%, manufactured by Kuraray) are added and stirred. Thereafter, 0.65 parts by mass of a 3% aqueous solution of boron oxide (B ₂ O ₃ , manufactured by Wako Pure Chemical Industries, Ltd.) was added, and after stirring, 0.008 parts by mass of acetylenic diol (Surfinol 104PA) was added, and ammonia 5% The pH was adjusted to 10.0 with an aqueous solution to obtain an overcoat paint having a solid content of 3% (pH = 10.0, dynamic surface tension 53 dyne / cm, static surface tension 48 dyne / cm).
The obtained overcoat paint was applied to the surface of the barrier layer of the gas barrier laminate produced in Example 1 with a gravure coater (forward gravure, 180 mesh, coating speed 100 m / min, drying temperature 95 ° C.) at a coating amount of 0. Coating was carried out so as to be 04 g / m ² (in terms of solid content) to produce a wound gas barrier laminate having an overcoat layer.

<Example 3>
Dry 100 parts by mass of a polypropylene resin (F300SP) and 0.2 parts by mass of an inorganic pigment masterbatch obtained by melt-mixing an inorganic pigment (silica with a particle diameter of 3.5 μm) and a polypropylene resin (F300SP) 5:95. A gas barrier laminate was produced in the same manner as in Example 2 except that the blended mixture was used as a resin for skin layer A to obtain an OPP film.
The surface roughness Rmax of the skin layer A of this OPP film was 118 nm, and Rz was 82 nm. Further, the surface roughness Rmax of the skin layer B was 644 nm, and Rz was 323 nm.

<Example 4>
Except that 100 parts by mass of polypropylene resin (F300SP) and 0.3 parts by mass of polyethylene resin (trade name LC522, manufactured by Nippon Polychem) were used as a resin for skin layer A to obtain an OPP film. A gas barrier laminate was produced in the same manner as in Example 2.
The surface roughness Rmax of the skin layer A of this OPP film was 126 nm, and Rz was 98 nm. Further, the surface roughness Rmax of the skin layer B was 638 nm, and Rz was 320 nm.

<Example 5>
Dry 100 parts by mass of a polypropylene resin (F300SP) and 0.8 parts by mass of an inorganic pigment master batch obtained by melt-mixing an inorganic pigment (silica having a particle diameter of 3.5 μm) and a polypropylene resin (F300SP) at a ratio of 5:95. A gas barrier laminate was produced in the same manner as in Example 2 except that the OPP film was obtained using the blended mixture as a resin to be the skin layer A.
The surface roughness Rmax of the skin layer A of this OPP film was 195 nm, and Rz was 133 nm. Further, the surface roughness Rmax of the skin layer B was 630 nm, and Rz was 329 nm.

<Example 6>
Dry 100 parts by mass of a polypropylene resin (F300SP) and 1.6 parts by mass of an inorganic pigment master batch obtained by melt-mixing an inorganic pigment (silica with a particle diameter of 3.5 μm) and a polypropylene resin (F300SP) at a ratio of 5:95. A gas barrier laminate was produced in the same manner as in Example 2 except that the blended mixture was used as a resin for skin layer A to obtain an OPP film.
The surface roughness Rmax of the skin layer A of this OPP film was 257 nm, and Rz was 188 nm. Further, the surface roughness Rmax of the skin layer B was 655 nm, and Rz was 341 nm.

<Example 7>
100 parts by mass of polypropylene resin (F300SP) was dry blended with 4 parts by mass of an inorganic pigment master batch obtained by melt-mixing an inorganic pigment (silica with a particle diameter of 3.5 μm) and polypropylene resin (F300SP) at a ratio of 5:95. A gas barrier laminate was produced in the same manner as in Example 2 except that the OPP film was obtained using the mixture as a resin for the skin layer B.
The surface roughness Rmax of the skin layer A surface of this OPP film was 105 nm, and Rz was 123 nm. The surface roughness Rmax of the skin layer B surface was 712 nm, and Rz was 396 nm.

<Example 8>
98 parts by mass of a polypropylene resin (F300SP) was dry blended with 2 parts by mass of an organic pigment master batch obtained by dispersing an organic pigment (PMMA powder having an average particle size of 5.0 μm) in a polypropylene resin (F300SP) at a concentration of 20%. A gas barrier laminate was produced in the same manner as in Example 2 except that the OPP film was obtained using the mixture as a resin for the skin layer B.
The surface roughness Rmax of the skin layer A surface of this OPP film was 155 nm, and Rz was 122 nm. The surface roughness Rmax of the skin layer B surface was 997 nm, and Rz was 756 nm.

<Example 9>
98 parts by mass of a polypropylene resin (F300SP) was dry blended with 2 parts by mass of an organic pigment master batch obtained by dispersing an organic pigment (PMMA powder having an average particle size of 7.0 μm) in a polypropylene resin (F300SP) at a concentration of 20%. A gas barrier laminate was produced in the same manner as in Example 2 except that the OPP film was obtained using the mixture as a resin for the skin layer B.
The surface roughness Rmax of the skin layer A surface of this OPP film was 186 nm, and Rz was 144 nm. The surface roughness Rmax of the skin layer B surface was 1690 nm, and Rz was 1310 nm.

<Example 10>
As a core layer, 100 parts by mass of polypropylene resin (PL400A) and a mixture obtained by dry blending 10 parts by mass of a petroleum resin masterbatch obtained by dry blending petroleum resin (Alcon P125) and polypropylene resin (PL400A) 1: 1 are used. A gas barrier laminate was produced in the same manner as in Example 2 except that an OPP film was obtained.
The surface roughness Rmax of the skin layer A surface of this OPP film was 104 nm and Rz was 84 nm, and the surface roughness of the skin layer B surface was Rmax 628 nm and Rz 286 nm.

<Example 11>
A gas barrier laminate was produced in the same manner as in Example 2 except that only the polypropylene resin (PL400A) was used as the core layer to obtain an OPP film.
The Rmax of the surface of the skin layer A of this OPP film was 103 nm and Rz was 83 nm. The Rmax of the surface of the skin layer B was 611 nm and Rz was 297 nm.

<Comparative Example 1>
100 parts by mass of polypropylene resin (F300SP) and 1.0 part by mass of an organic pigment master batch obtained by dispersing an organic pigment (PMMA powder having an average particle size of 3.0 μm) in polypropylene resin (F300SP) at a concentration of 20% are dried. The mixture obtained by blending is used as the resin that becomes the skin layer A, only the polypropylene resin (PL400A) is used as the resin that becomes the core layer, and only the polypropylene resin (F300SP) is used as the resin that becomes the skin layer B. A gas barrier laminate was produced in the same manner as in Example 2 except that an OPP film was obtained. When this gas barrier laminate was finished by winding, the blocking was intense and the appearance was poor.
The surface roughness Rmax of the skin layer A surface of this OPP film was 630 nm and Rz 310 nm. The surface roughness of the skin layer B surface was 103 nm, and Rz was 83 nm.

<Comparative example 2>
Dry blend of 20 parts by mass of a petroleum resin master batch obtained by melt-mixing petroleum resin (Alcon P125) and polypropylene resin (PL400A) at a ratio of 1: 1 to 100 parts by mass of polypropylene resin (F300SP). The resulting mixture was obtained.
Organic pigment master batch obtained by dispersing organic pigment (PMMA powder having an average particle size of 3.0 μm) in polypropylene resin (F300SP) at a concentration of 20% in 98 parts by mass of polypropylene resin (F300SP) as the resin for layer B A mixture obtained by dry blending 2 parts by mass was obtained.
The above two types of resins were extruded using a two-type two-layer T-die melt extrusion film forming apparatus. A 1000 μm-thick film formed from a T-die was stretched 5 times at 145 ° C. by a conventional sequential biaxial stretching machine, and then 10-fold transverse stretching at 150 ° C. to obtain an OPP film.
The thickness of the obtained OPP film was 20 μm (layer A = 18 μm, layer B = 2 μm).
The surface roughness Rmax of the A layer of this OPP film was 330 nm, and Rz was 285 nm. The surface roughness Rmax of the B layer was 620 nm, and Rz was 309 nm.

Next, the same anchor paint as that obtained in Example 1 was subjected to corona treatment on the A layer side of the OPP film, and then a gravure coater (forward gravure, 180 mesh, coating speed 100 m / min, drying temperature). The anchor layer was formed by coating so that the coating amount was 0.12 g / m ² (in terms of solid content) at 95 ° C.).
Next, the same gas barrier paint as that obtained in Example 1 was applied on the anchor layer with a gravure coater (forward gravure, 180 mesh, coating speed 100 m / min, drying temperature 95 ° C.). Coating was carried out so as to be 0.12 g / m ² (in terms of solid content) to produce a wound gas barrier laminate.

<Comparative Example 3>
An OPP film is obtained as follows.
98 parts by mass of a polypropylene resin (F300SP) was dry blended with 2 parts by mass of an organic pigment master batch obtained by dispersing an organic pigment (PMMA powder having an average particle size of 3.0 μm) in a polypropylene resin (F300SP) at a concentration of 20%. The mixture was extruded using a single layer T-die melt extrusion film forming apparatus. A 1000 μm thick film formed from a T-die was longitudinally stretched 5 times at 145 ° C. by a conventional sequential biaxial stretching apparatus, and then stretched 10 times at 150 ° C. to obtain an OPP film. The thickness of the film was 20 μm.
The surface roughness of this OPP film is that Rmax on one side is 642 nm, Rz is 320 nm (this side is A plane), Rmax on the opposite side is 633 nm, and Rz is 316 nm. there were.

Next, the same anchor paint as that obtained in Example 1 was subjected to corona treatment on the A side of the OPP film, and then a gravure coater (forward gravure, 180 mesh, coating speed 100 m / min, drying temperature) The anchor layer was formed by coating so that the coating amount was 0.12 g / m ² (in terms of solid content) at 95 ° C.).
Next, the same gas barrier paint as that obtained in Example 1 was applied on the anchor layer with a gravure coater (forward gravure, 180 mesh, coating speed 100 m / min, drying temperature 95 ° C.). The gas barrier layer was formed by coating so as to be 0.12 g / m ² (in terms of solid content).
Next, the same overcoat paint as that obtained in Example 2 was applied to the surface of the gas barrier layer with a gravure coater (forward gravure, 180 mesh, coating speed 100 m / min, drying temperature 95 ° C.) and the coating amount was 0. A wound gas barrier laminate having an overcoat layer was produced by coating so that the amount was 0.04 g / m ² (in terms of solid content).

The gas barrier laminates obtained in Examples and Comparative Examples were measured and evaluated by the following methods. The results are shown in Tables 1 and 2.
<Test method>
1) Surface roughness of OPP film The surface roughness was determined with an atomic force microscope. Rmax represents the maximum height, and Rz represents the 10-point average height. Measurement equipment and measurement conditions are as follows.
Seiko Instruments Inc., Model: NANOPICS1000
Measuring head: AFM (NP1) Damping mode Scanner sensitivity: X / Y / Z = 5000/5000/1000 nm / V
Scanning mode: 1 screen measurement Scanning area / frequency: 100.3 × 100.3 μm / 0.67 Hz
Bias voltage: 1.000V
I gain / P gain: 14/10

2) Evaluation of moisture-resistant adhesion To 113 parts by mass of ethyl acetate, 100 parts by mass of urethane-based adhesive (Trademark Nipponran ID-816, solid content 60%, manufactured by Nippon Polyurethane Industry Co., Ltd.) is added and stirred with an isocyanate-based curing agent (product) 5.6 parts by mass (name hardener 300, solid content 100%, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to prepare an adhesive for dry lamination having a solid content of 30%.
On the gas barrier layer of the gas barrier laminate obtained in Examples and Comparative Examples, the adhesive was applied with a Meyer bar so that the solid content after drying was 3.5 g / m ^2, and at 80 ° C. for 30 seconds. It dried and the adhesive bond layer was formed.
The adhesive layer and the corona-treated surface side of a pre-corona-treated unstretched polypropylene film (trade name: Pyrene Film-OT, product number P-1128, 20 μm thickness, manufactured by Toyobo Co., Ltd.) are superposed on each other with a 40 ° C. incubator. Aging was performed for a day to obtain a dry laminate product.
From the dry laminate product, a strip-shaped test piece having a TD direction of 15 mm × MD direction of 200 mm was prepared.
The test piece was measured for 3 days in a constant temperature and humidity chamber at 23 ° C. and 90% RH, and then T-shaped peeling was performed at a tensile speed of 300 mm / min with a Tensilon type tensile tester. The peel strength was defined as adhesion. However, when the gas barrier laminate or unstretched polypropylene film was broken at the time of peeling, the strength at the time of the break was regarded as adhesion.
The adhesion is preferably 0.5 N / 15 mm or more, and more preferably 1 N / 15 mm or more.

3) Oxygen permeability After leaving the gas barrier laminates obtained in Examples and Comparative Examples for one week in a state where the coating layer is in contact with an atmosphere of 23 ° C. and 90% RH, JIS-K-7126 B method (isobaric method) Then, the coated surface was measured on the oxygen detector side at 23 ° C. and 90% RH conditions (oxygen permeability measuring device: OX-TRAN100 type, manufactured by MOCON). The oxygen permeability was a value 72 hours after setting the sample.
Oxygen permeability is preferably at most 20cc / ^{m 2} · 24hr, more preferably not more than 10cc / ^{m 2} · 24hr, more preferably not more than 5cc / ^{m 2} · 24hr.

4) Water vapor permeability Using the gas barrier laminates obtained in the examples and comparative examples, a water vapor gas permeability measuring device (PERMATRAN-W3 / 31, manufactured by Modern Control Co., Ltd.) in an environment of 40 ° C. and 90% RH. I went. If the moisture permeability is 10g / m ² · 24hr or less, there is practicality. If the moisture permeability is less than 6g / m ² · 24hr, the application is expanded. If the moisture permeability is less than 4g / m ² · 24hr, the use is further increased. It is suitable for enlargement.

Claims (4)

In the gas barrier laminate in which a gas barrier layer containing a silicic acid condensate is provided on one side of a biaxially oriented polypropylene film, the surface roughness of the film is Rmax 300 nm or less on the gas barrier layer side and Rz 200 nm or less, and the opposite side of the gas barrier layer is Rmax 300 to A gas barrier laminate having 2000 nm and Rz 200 to 1500 nm. The biaxially stretched polypropylene film has a three-layer structure of a skin layer A, a core layer, and a skin layer B. The core layer contains a moisture-proof improving resin, the skin layer B contains a pigment, and the skin layer A side. The gas barrier laminate according to claim 1, wherein the gas barrier layer is provided via an anchor layer. The gas barrier laminate according to claim 2, wherein the pigment is an organic pigment. The gas barrier laminate according to any one of claims 1 to 3, wherein an overcoat layer containing colloidal silica is provided on the gas barrier layer.