JP2005186291A - Manufacturing method of laminate having thin film layer having high adhesion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a laminate excellent in gas barrier properties and having a thin film layer having a very high adhesion strength. <P>SOLUTION: The laminate is constituted by successively laminating a primer layer and the thin film layer with a thickness of 5-300 nm comprising an inorganic oxide at least on one side of a base material and heat-treated under a temperature condition higher than a temperature near to the glass transition temperature of the resin of the primer layer (e.g., 70°C×7 days) to relax the internal stress of the primer layer. By this method, the adhesion of the thin film layer of the laminate can be enhanced and the delamination of the laminate is not brought about even in a case used under a severe condition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a laminate for packaging used in various packaging fields such as foods, non-foods, and pharmaceuticals, and particularly relates to the packaging field where high adhesion is required.

Packaging materials used for packaging foods and non-foods contain oxygen, water vapor, or other gas that alters the contents that permeate the packaging materials in order to suppress the deterioration of the contents and maintain their functions and properties. It is necessary to prevent the influence, and it is required to have a gas barrier property that blocks these gases. Furthermore, since what is packaged is diversified in recent years, what has the strong adhesiveness in which adhesiveness does not fall with the content is requested | required. Therefore, conventionally, a packaging material using a metal foil made of a metal such as aluminum, which is less affected by temperature, humidity and the like and less deteriorated in adhesion due to various contents, has been generally used.
However, packaging materials using metal foils made of metal such as aluminum are excellent in gas barrier properties and adhesion, but the contents cannot be confirmed through the packaging materials. It is difficult to use because it has the disadvantage that it has to be processed as a metal detector and the use of metal detectors cannot be used. is there.
Accordingly, as a packaging material that overcomes these drawbacks, an inorganic oxide such as silicon oxide, aluminum oxide, tin oxide or the like as described in, for example, US Pat. No. 3,442,686 and Japanese Patent Publication No. 63-28017 is used as a polymer film. On top of this, a film in which a deposited film is formed by a forming means such as a vacuum deposition method or a sputtering method has been developed. These films have transparency and gas barrier properties such as oxygen and water vapor, and can be incinerated, so they are also environmentally friendly, both gas barrier properties and environmental properties that cannot be obtained with metal foil, etc. It is suitable as a packaging material having
These films are further laminated with sealant films and other resin films and used as various packaging materials.

  In use as such a packaging material, depending on the contents to be stored, the strength between the base material and the inorganic oxide thin film layer may decrease, and in order to improve the adhesion strength of this thin film layer, the base material A technique for forming a primer layer on the top has been proposed.

As this primer layer, it is known that suitable adhesion can be obtained by using a mixture of a polyester resin and an isocyanate resin. (Prior Art Document 1)
Japanese Patent Laid-Open No. 10-723

  By providing such a primer layer, the adhesion of the thin film layer is significantly improved.

  However, when the above-described laminate is used for a container having a shape or structure that is more permeable or physically stressed, the primer layer itself existing between the base material and the thin film layer is destroyed, and the laminate Has been found to cause delamination.

Accordingly, the present invention was made for the purpose of preventing delamination due to the destruction of the primer layer, and the invention according to claim 1 is characterized in that the primer layer, the thickness is formed on at least one surface of a base material made of a plastic material. A laminate comprising a thin film layer having high adhesion, characterized by heat-treating a laminate obtained by sequentially laminating a thin film layer having a thickness of 5 to 300 nm at a temperature close to the glass transition temperature of the resin of the primer layer It is a manufacturing method.

  In the invention according to claim 2 of the present invention, a resin film is further laminated on a thin film layer surface of a film in which a primer layer and a thin film layer having a thickness of 5 to 300 nm are sequentially laminated on at least one surface of a base material made of a plastic material. In the method for producing a laminate including a thin film layer having high adhesion, the laminate is heat-treated at a temperature near the glass transition temperature of the resin of the primer layer.

  Invention of Claim 3 of this invention is a manufacturing method of said laminated body characterized by the primer layer being formed with the composition containing the resin component which has a reactive functional group.

  According to a fourth aspect of the present invention, there is provided the method for manufacturing a laminate, wherein a protective layer for the thin film layer is formed on the thin film layer.

  According to the present invention described above, a laminate having excellent adhesion without deterioration of the laminate strength due to the influence of contents or physical stress can be obtained, so that it can be used as a packaging material used under extremely severe conditions. Useful.

Hereinafter, the present invention will be described in detail.
The 1st example of the laminated body of this invention consists of a structure by which the primer layer and the thin film layer were laminated | stacked in order on the base material which consists of a plastic material.

  The base material mentioned above is a plastic material, and becomes a base material in forming a primer layer or a thin film layer. For example, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, polyimide films, etc. are used for stretching Either unstretched or unstretched, and those having mechanical strength and dimensional stability are preferred. These are processed into a film and used. In particular, polyethylene terephthalate arbitrarily stretched in the biaxial direction is preferably used. In addition, various well-known additives and stabilizers such as an antistatic agent, an anti-ultraviolet agent, a plasticizer, and a lubricant may be used on the surface of the base material, in order to improve the adhesion to the thin film. As a pretreatment, a corona treatment, a low-temperature plasma treatment, an ion bombardment treatment may be performed, and a chemical treatment, a solvent treatment, or the like may be further performed.

  The thickness of the base material is not particularly limited, but it is practical considering the suitability as a packaging material, that other layers may be laminated, and the workability when forming a primer layer and a thin film layer. Is preferably in the range of 3 to 200 μm and preferably 6 to 30 μm depending on the application.

  In consideration of mass productivity, it is desirable to use a long film so that each layer can be formed continuously.

  The primer layer of the present invention is provided on a base material made of a plastic material, and is provided for the purpose of enhancing the adhesion between the base material and the thin film layer and suppressing a decrease in laminate strength due to the influence of the contents. It is.

  Any resin material can be used as the primer resin as long as it can improve the adhesion between the base material and the thin film layer, but the polyester resin alone or the resin and isocyanate resin, epoxy resin, It is preferably a mixture with one or more mixed resins selected from melamine resins. In particular, a composition containing these resins as components as the resin can firmly bond the base material and the thin film layer by the reaction of the functional group of each resin.

  Examples of the polyester resin include terephthalic acid, isophthalic acid, phthalic acid, methylphthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, Acid raw materials such as hexahydrophthalic acid and reactive derivatives thereof, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, 1 , 4-cyclohexanedimethanol, neopentyl glycol, isopentyl glycol, bishydroxyethyl terephthalate, hydrogenated bisphenol A, hydrogenated bisphenol A alkylene oxide adduct, trimethylolethane, trimethylo Trimethylolpropane, glycerol, pentaerythritol, 2,2,4-alcohol starting materials such as trimethyl-1,3-diol those produced by a known method but can be used is not particularly limited thereto.

The mixed resin added to the polyester resin is added to further improve the adhesion, and mainly acts as a crosslinking agent or a curing agent. To achieve this, mixed resins include isocyanate resins such as tolylene diisocyanate (TDI), xylene diisocyanate (XDI), and hexadiisocyanate (MDI), bisphenol A diglycine ether type epoxy, hydrogenated bisphenol type epoxy, etc. Epoxy resins, melamine resins, and mixtures of one or more of these can be used. Among them, the case of using an isocyanate-based resin (particularly TDI) is preferable because it has the best adhesion.

  As a mixing ratio of the polyester resin and the mixed resin, an isocyanate group, an epoxy group, an amino group, or the like may be contained in an equivalent amount or more with respect to the OH group or COOH group of the polyester resin. For example, when an isocyanate-based resin alone is used as a mixed resin, the blending ratio of the polyester resin and the isocyanate-based resin is an equivalent ratio of (OH group of polyester) :( NCO group of isocyanate) = 1: 0.5 to 1:20. A range is desirable. If it is equal to or less than the equivalent, there will be a problem in adhesion due to poor curing and insufficient crosslinking. However, adding too much is not preferred because the added resin does not react and adversely affects the remaining film. About the method of mixing, a well-known method can be used and it does not specifically limit.

  The solvent for dissolving the primer resin is not particularly limited as long as it can dissolve the resin. For example, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, toluene In addition, aromatic hydrocarbons such as xylene can be used alone or arbitrarily blended. Preferably, a one-to-one mixture of toluene and methyl ethyl ketone is preferable in terms of coating film processing and odor.

  Various additives such as tertiary amines, imidazole derivatives, carboxylic acid metal salt compounds, quaternary ammonium salts, quaternary borophonium salts, etc., primer-based, sulfur-based, phosphite-based, etc. Antioxidants, leveling agents, flow regulators, catalysts, crosslinking reaction accelerators, fillers and the like can be added.

  Although the thickness of a primer layer will not be specifically limited if a coating film can be formed uniformly, Generally it is preferable that it is the range of 0.01 micrometer-1.0 micrometer. If the thickness is less than 0.01 μm, it is difficult to obtain a uniform coating film, and the adhesion may be partially reduced. On the other hand, when the thickness exceeds 1.0 μm, flexibility cannot be maintained in the coating film, and cracks may occur in the coating film due to external factors. Considering safety, it is particularly preferable that the thickness is in the range of 0.1 to 1.0 μm.

  As a method for forming the primer layer, for example, a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a known coating method such as roll coating, knife edge coating, or gravure coating can be used. About drying conditions, generally used conditions may be used.

  Next, the thin film layer is formed by forming a metal such as aluminum or an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof on a substrate by a known method described later. It is. The thin film layer is preferably one that can be incinerated from the viewpoint of environmental suitability and has gas barrier properties such as oxygen and water vapor. Among them, aluminum oxide and silicon oxide are particularly preferable for use as a packaging material because they are excellent in physical properties and transparent. However, the thin film layer of the present invention is not limited to the inorganic oxide described above, and any material that meets the above conditions can be used.

  Although the optimum conditions for the thickness of the thin film layer vary depending on the type and configuration of the metal or inorganic compound used, it is generally desirable that the thickness be in the range of 5 to 300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. Further, when the film thickness exceeds 300 nm, it becomes difficult to maintain flexibility in the thin film. Therefore, there is a possibility that the thin film is cracked due to external factors such as bending and pulling after the film formation. Preferably, it is in the range of 10 to 150 nm.

There are various methods for forming a thin film layer on a primer layer, which can be formed by a normal vacuum deposition method, but other thin film formation methods such as sputtering, ion plating, and plasma vapor deposition (CVD). ) Etc. can also be used.
However, considering productivity, the vacuum deposition method is the best at present. As the heating means of the vacuum evaporation apparatus by the vacuum evaporation method, it is preferable to use an electron beam heating method, a resistance heating method, or an induction heating method. In order to improve the adhesion between the thin film and the substrate and the denseness of the thin film, plasma assist It is also possible to use an ion beam assist method. In addition, in order to increase the transparency of the deposited film, it is possible to carry out reactive deposition by blowing oxygen gas or the like during deposition.

  In the present invention, a heat treatment at a temperature equal to or higher than the glass transition temperature (Tg) of the resin of the primer layer is performed on the laminate obtained by sequentially laminating the base material, the primer layer, and the thin film layer.

  When forming a primer layer using a composition containing a resin having a reactive functional group such as the isocyanate resin described above, a composition in which the resin is dissolved in an appropriate solvent is applied onto the substrate. Then, after evaporating the solvent, aging treatment (heating treatment) is performed at 50 ° C. for about 3 days to promote the reaction. The heat treatment of the present invention is performed after the thin film layer is formed on the primer layer. It means the heat treatment performed again.

  The second feature of the heat treatment of the present invention is that the heat treatment is performed at a temperature equal to or higher than the glass transition temperature (Tg) of the resin of the primer layer.

  The temperature near the glass transition temperature (Tg) of the resin of the primer layer is a temperature at which the effect of the present invention can be obtained and depends on the type of the resin, but refers to a temperature of about 5 ° C. lower than Tg. For example, in a suitable example of a primer using an isocyanate resin as a resin mixed with a polyester resin, the Tg of the resin is about 67 ° C., and the temperature of the heat treatment of the present invention is 62 ° C. or higher, preferably 67 ° C. or higher, which is Tg. More preferably, the temperature is preferably set to 70 ° C. slightly higher than Tg. The heat treatment time is preferably as long as possible. From the viewpoint of stress relaxation described later, the heat treatment time is at least 1 day, preferably 3 days or more, more preferably 5 days or more. It is preferable.

  The reason why the adhesiveness of the thin film layer is improved by performing the above heat treatment has not been fully clarified, but can be estimated as follows.

  The primer layer usually has internal stress for various reasons. For example, in general, a material to be formed is thermally damaged when forming a thin film layer. In the case of the present invention, since the thin film layer is formed on the primer layer, the primer layer receives thermal damage when the thin film layer is formed, and internal stress is generated in the primer layer due to this thermal damage.

  And it is thought that the said internal stress is relieve | moderated by performing heat processing after thin film layer formation like this invention, and the adhesiveness of a thin film layer improves.

  In addition, when the primer layer uses a reactive material, the unreacted reactive material that could not be reacted by the so-called aging treatment by the heat treatment of the present invention moves in the resin softened by heating, It is also conceivable that stronger adhesiveness is realized by reacting the reactive material that has moved to the substrate surface and the thin film layer surface with the substrate or the thin film layer.

  Furthermore, since the internal stress also exists in the base material, it is considered that the relaxation of the internal stress of the base material by the heat treatment also contributes to the improvement of the adhesion of the thin film layer.

  The effects of the present invention are considered to be related to the above factors.

  As a laminated body of this invention, in addition to the above-mentioned base material, a primer layer, and a thin film layer, it is also possible to laminate | stack another layer on a thin film layer. For example, a printing layer. The printed layer is formed for practical use as a packaging bag, etc., and various pigments are added to conventionally used ink binder resins such as urethane, acrylic, nitrocellulose, rubber and vinyl chloride. , A layer composed of an ink to which additives such as extender pigments, plasticizers, desiccants, stabilizers and the like are added, and characters, patterns, etc. are formed. As a forming method, for example, a known printing method such as an offset printing method, a gravure printing method, or a silk screen printing method, or a known coating method such as a roll coating, a knife edge coating, or a gravure coating can be used. The thickness may be 0.1 to 2.0 μm.

  Moreover, when using the laminated body of this invention as a packaging material, it is preferable to form the sealant layer which consists of a polyolefin-type thermoplastic resin in the side used as the innermost layer of a laminated body. In addition to forming the polyolefin-based thermoplastic resin on the thin film layer, an intermediate layer can be provided as necessary. This intermediate layer is provided to further functionalize the packaging material, such as imparting tearability and increasing the waist strength of the packaging material. Any material can be selected and used according to consumer requirements, suitability of contents, etc. be able to. For example, when imparting tearability, a uniaxially stretched nylon film, a uniaxially stretched polyethylene terephthalate film, a uniaxially stretched polypropylene film, or the like can be used. In order to increase waist strength, a biaxially stretched polyethylene terephthalate film or a biaxially stretched film can be used. A plastic material such as a polypropylene film can be used.

  The thickness of the intermediate layer is determined according to the material, required quality, required physical properties, etc., but is generally in the range of 10 to 30 μm. As a method for forming the intermediate layer, a known method such as a dry laminating method in which an adhesive such as a two-component curable urethane resin is bonded or an extrusion laminating method in which a heat-melted resin is extruded and bonded in a curtain shape is used. Although it can be laminated by using, generally a dry lamination method is often used.

  The polyethylene-based thermoplastic resin layer is used for an adhesive portion when forming a bag-like package body, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene. -Resins such as methacrylic acid ester copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, and their metal cross-linked products are used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm. As a forming method, a film-like product made of the above resin is bonded by using an adhesive such as a two-component curable urethane resin, a method of laminating by a non-solvent laminate, and the resin is heated and melted to form a curtain. Any of the extrusion laminating method, the extrusion method, and the knee laminating method can be laminated by a known method.

  Furthermore, another layer can be laminated on the surface of the substrate opposite to the surface on which the thin film layer is formed. For example, a printing layer and other functional layers. The printed layer is formed for practical use as a packaging bag, etc., and various pigments are added to conventionally used ink binder resins such as urethane, acrylic, nitrocellulose, rubber and vinyl chloride. In addition, it is a layer composed of ink to which additives such as extender pigments, plasticizers, desiccants, stabilizers, and the like are added, and letters, pictures, and the like are formed. As a forming method, for example, a known printing method such as an offset printing method, a gravure printing method, or a silk screen printing method, or a known coating method such as a roll coating, a knife edge coating, or a gravure coating can be used. The thickness may be 0.1 to 2.0 μm. Further, there are various other functional layers depending on the required quality, and the layer can be formed by any known method such as a dry laminating method or an extrusion laminating method.

  Furthermore, a protective layer for the thin film layer can be formed on the thin film layer as necessary. The thin film layer is a very thin film, and can be damaged relatively easily by physical stimuli such as rubbing and in some cases may fall off from the substrate. Therefore, after forming the thin film layer, before performing other processing It is meaningful to form a protective layer.

  As the protective layer, any resin may be formed by a method such as coating. For example, a protective layer is formed by forming a coating agent mainly composed of a water-soluble polymer such as polyvinyl alcohol on the thin film layer. Can do.

Next, the strong adhesion gas barrier laminate of the present invention will be further described with reference to specific examples.
<Example 1>
As a substrate, a resin having the following composition was formed as a primer layer on one side of a biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm by a gravure coating method.
Resin: Polyester / isocyanate-based compounding ratio: OH group (polyester) / NCO group (isocyanate) = 1/8 (equivalent ratio)
Thickness: 0.1μm
Solvent: Toluene / Methyl ethyl ketone = 1/1
Next, a thin film layer made of an inorganic oxide was formed on the primer layer by vapor deposition of silicon oxide to a thickness of about 40 nm using a resistance heating vacuum deposition apparatus.

  With the thin film layer formed, heat treatment was performed at 70 ° C. for 7 days. Specifically, the roll which made the long film of the said laminated body the winding shape was stored in the room | chamber interior of the said conditions.

  Next, a polyethylene film having a thickness of 50 μm is laminated as a polyolefin-based thermoplastic resin layer on the thin film layer surface of the laminate by a dry laminating method via a two-component curable urethane-based adhesive, and the gas barrier laminate of the present invention. Got the body.

When a laminated tube container was manufactured using the obtained laminate, no problems occurred in the content resistance, pressure strength, and the like.
<Comparative Example 1>
A gas barrier laminate obtained in the same manner as in Example 1 except that heat treatment at 70 ° C. for 7 days was not performed, and a laminate tube container similar to that in Example 1 was prepared.

  Although the obtained container showed no problem with respect to the content resistance, the container was broken during the pressure strength test. When the damaged container was observed, the primer layer was broken and delamination was generated between the base material and the thin film layer. The primer layer had a so-called zippering shape in which a part of the primer layer was present on the substrate side and another part was present on the thin film layer side.

Claims (4)

A laminate in which a primer layer and a thin film layer having a thickness of 5 to 300 nm are sequentially laminated on at least one surface of a base material made of a plastic material, is heat-treated at a temperature near the glass transition temperature of the resin of the primer layer. The manufacturing method of the laminated body provided with the thin film layer which has high adhesiveness to do. A primer layer resin glass is applied to a laminate obtained by further laminating a resin film on a thin film layer surface of a film obtained by sequentially laminating a primer layer and a thin film layer having a thickness of 5 to 300 nm on at least one surface of a base material made of a plastic material. A method for producing a laminate including a thin film layer having high adhesion, wherein the heat treatment is performed at a temperature equal to or higher than a transition temperature. The method for producing a laminate according to claim 1, wherein the primer layer is formed of a composition containing a resin component having a reactive functional group. The manufacturing method of the laminated body in any one of Claim 1 thru | or 3 which formed the protective layer of the thin film layer on the thin film layer.