JP2005144978A - Gas barrier laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas barrier laminated film which shows excellent gas barrier property to oxygen and water vapor, has transparency, flexibility and humidity resistance, and can be easily manufactured. <P>SOLUTION: The gas barrier laminated film is obtained by laminating a covering layer containing an organic compound having two or more functional groups capable of reacting with a hydroxyl group and a hydroxyl group-containing organic resin as essential components on a base material composed of a polymer resin composition, and further laminating an inorganic thin layer on it. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas barrier laminate film used in the packaging field of foods, pharmaceuticals and the like.

  Packaging materials used for foods, pharmaceuticals, etc. are: 1) inhibition of oxidation of proteins and fats, 2) maintenance of taste and freshness, 3) property of blocking gases such as oxygen and water vapor in order to maintain the efficacy of pharmaceuticals, ie gas barrier It is required to have sex. Therefore, a polymer resin generally known to have a relatively high gas barrier property such as polyvinyl alcohol (hereinafter referred to as PVA), ethylene vinyl alcohol copolymer (EVOH), or polyvinylidene chloride resin (hereinafter referred to as PVDC). Films laminated with compositions have been used as packaging materials. Also, a film of a suitable polymer resin composition (even if it is a resin that does not have high gas barrier properties alone) is deposited with a metal such as Al, or an inorganic oxide such as alumina or silica. Things are also starting to be commonly used as packaging materials.

  However, since the gas barrier laminate film using the above-described PVA and EVOH polymer resin composition has large temperature dependency and humidity dependency, the gas barrier property is lowered at high temperature or high humidity. That is, when a boiling process or a retort process is performed, the gas barrier properties are significantly lowered. In addition, the gas barrier laminate film using the PVDC polymer resin composition has a small gas barrier humidity dependency, but has a high gas barrier property such as an oxygen barrier property of 10 ml / m 2 · day · Mpa or less. It is difficult to realize. In addition, since the coating contains a large amount of chlorine, there is a problem in terms of waste treatment such as incineration and recycling.

  In addition, the above-mentioned metal-deposited films and films deposited with inorganic oxides such as alumina and silica have very different physical properties such as mechanical properties, chemical properties, and thermal properties between the deposits and the resin films. Therefore, the inorganic thin film used for the gas barrier layer lacks flexibility and is weak against stagnation and bending. Moreover, since the adhesiveness with a base material is bad, handling is required and there exists a problem which a crack generate | occur | produces at the time of post-processing of packaging materials, such as printing, a laminate, and a bag making, and gas barrier property falls remarkably. Further, since the apparatus is formed using a vacuum process, the apparatus is expensive, the temperature is locally high in the forming process, the substrate is damaged, the low molecular weight part or the additive part such as a plasticizer is decomposed and removed Defects, pinholes, etc. may occur in the deposited layer due to gas or the like. That is, conventional vapor deposition films have problems that they cannot achieve high gas barrier properties and are expensive in cost.

In view of the above problems, a gas barrier material in which a metal alkoxide film is formed on a base material has been proposed (see, for example, Patent Document 1). Since this gas barrier material has a certain degree of flexibility and can be manufactured by a liquid phase coating method, it can be made inexpensive in terms of cost.
JP-A-62-295931

  However, the gas barrier material can be said to have improved gas barrier properties as compared with the case of a single substrate, but cannot be said to have high gas barrier properties.

  An object of the present invention is to provide a gas barrier laminated film that has excellent gas barrier properties against oxygen and water vapor, has flexibility, moisture resistance, and heat resistance and is easy to manufacture.

The gas barrier laminate film according to claim 1 is a coating comprising, as essential components, an organic compound containing two or more hydroxyl-reactive functional groups and an organic resin containing a hydroxyl group on a substrate made of a polymer resin composition. It is characterized by laminating layers and further laminating an inorganic thin film layer thereon.
The gas barrier laminate film according to claim 2, wherein the organic compound containing a hydroxyl-reactive functional group in the gas barrier laminate film according to claim 1 is a methylol melamine in which some or all of the methylol groups are alkyl etherified. It is characterized by being.
The gas barrier laminate film according to claim 3 is the gas barrier laminate film according to claim 1 or 2, wherein the organic resin containing a hydroxyl group is a polyvinyl alcohol polymer.
The gas barrier laminate film according to claim 4 is the gas barrier laminate film according to claims 1 to 3, wherein the weight ratio of the organic compound containing a hydroxyl-reactive functional group / the organic resin containing a hydroxyl group is more than 20/80. It is characterized by laminating a large covering layer.

  According to the present invention, an oxygen barrier property, water vapor barrier property, flexibility, moisture resistance, and heat resistance are excellent, and dioxin and hydrogen chloride gas are not contained in the incineration exhaust gas, and a film effective for environmental conservation is provided. it can.

Hereinafter, embodiments of the gas barrier laminate film and the method for producing the same according to the present invention will be described.
The base material layer used in the present invention is, for example, a film obtained by melt-extruding an organic polymer and stretching, cooling, and heat setting in the longitudinal direction and / or the width direction as necessary. Polyester represented by nylon 4,6, nylon 6, nylon 6,6, nylon 12, etc., represented by polyamide, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, etc., polyester, polyethylene, polypropylene, polybutene In addition to polyolefins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, polystyrene, and polylactic acid.

  The base material layer according to the present invention may be of any film thickness depending on the desired purpose such as mechanical strength and transparency. Although not particularly limited, it is usually recommended to be 5 to 250 μm, and when used as a packaging material, it is preferably 10 to 60 μm.

  The base material layer in the present invention may be a laminated film. There are no particular limitations on the type of laminate, the number of laminations, the lamination method, and the like in the case of a laminated film, and any one of known methods can be selected according to the purpose.

  A specific coating layer is laminated on at least one surface of such a base material layer. As the coating layer, an organic compound containing two or more hydroxyl-reactive functional groups and an organic resin containing a hydroxyl group are essential components. The organic compound containing a hydroxyl-reactive functional group needs to contain two or more hydroxyl-reactive functional groups in order to crosslink the organic resin containing a hydroxyl group.

Such organic compounds containing two or more hydroxyl-reactive functional groups include dialdehyde compounds such as glyoxal and glutaraldehyde, dicarboxylic acids such as succinic acid and adipic acid, and diisocyanate compounds such as diphenylmethane diisocyanate and hexamethylene diisocyanate. And methylol compounds such as epoxy compounds, methylol urea, and methylol melamine. Of these, methylol melamine, in which some or all of the methylol groups are alkyl etherified, is preferred from the standpoint of gas barrier properties.
The methylol melamine, in which part or all of the methylol group is alkyl etherified, has at least a part of hydrogen atoms of three amino groups bonded to the triazine ring substituted with a methylol group, and the number of methylol groups Is generally 3 to 6, and some or all of the methylol groups are alkyl etherified. The alkyl moiety of the alkyl etherified methylol melamine is a linear or branched chain having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. For example, methyl, ethyl, n- or iso-propyl, n-, iso- or tert-butyl. Specific examples of methylol melamine used in the present invention include hexakismethoxymethyl melamine, hexamethylol melamine pentamethyl ether, hexamethylol melamine tetramethyl ether, pentamethylol melamine pentamethyl ether, pentamethylol melamine tetramethyl ether, penta Examples include methylol melamine trimethyl ether, tetramethylol melamine tetramethyl ether, tetramethylol melamine trimethyl ether, trimethylol melamine trimethyl ether, and trimethylol melamine dimethyl ether. From the point of compatibility with polyvinyl alcohol polymers, trimethylol melamine Trimethyl ether and trimethylol melamine dimethyl ether are preferably used. The methylol melamine may contain a part of a condensate such as a dimer.

On the other hand, examples of the organic resin containing a hydroxyl group used in the present invention include a resin containing a hydroxyl group at a side chain or a terminal. Specifically, acrylic polymers, fluoroolefin polymers, vinyl ester polymers, aromatic vinyl polymers, polyolefin polymers, polyester polymers, alkyd polymers, polyurethane polymers, etc. Polyester resins, polyurethane resins, acrylic resins, polyvinyl alcohol polymers, cellulose and derivatives thereof, starch, and the like. Especially, it is preferable to use a polyvinyl alcohol-type polymer at the point of expression of the gas barrier property which is the objective of this invention.
The polyvinyl alcohol polymer has a vinyl alcohol unit as a main component, and the polymerization degree and saponification degree of the polyvinyl alcohol polymer are determined from the target gas barrier properties and the viscosity of the aqueous coating solution. The degree of polymerization is preferably 2600 or less from the viewpoint of coating workability because the aqueous solution viscosity is high and gelation tends to be difficult. If the saponification degree is less than 90%, sufficient oxygen gas barrier properties under high humidity cannot be obtained, and if it exceeds 99.7%, it is difficult to prepare an aqueous solution, and gelation tends to occur, which is not suitable for industrial production. Therefore, the saponification degree is preferably 90 to 99.7%, more preferably 93 to 99%. Various copolymerized or modified polyvinyl alcohol polymers such as a polyvinyl alcohol polymer copolymerized with ethylene and a polyvinyl alcohol polymer modified with silanol can also be used.

  In the present invention, the weight ratio of the organic compound containing two or more hydroxyl-reactive functional groups and the organic resin containing a hydroxyl group can be arbitrarily selected. From the viewpoint of gas barrier properties, a methylolmelamine / polyvinyl alcohol polymer is used. The weight ratio is preferably 20/80 to 95/5, more preferably 50/50 to 90/10. If this ratio is smaller than 20/80 or larger than 95/5, the target oxygen barrier property and water vapor barrier property will not be sufficiently exhibited.

  The coating layer containing, as essential components, an organic compound containing two or more hydroxyl-reactive functional groups and an organic resin containing a hydroxyl group used in the present invention is usually formed by coating with a solvent. As a solvent for the coating liquid, it is preferable to use 100% water or a water / lower alcohol mixed solvent from the viewpoint of solubility. The lower alcohol is an alcoholic compound having a linear or branched aliphatic group having 1 to 3 carbon atoms, and specific examples include methanol, ethanol, ethylene glycol, n- or iso-propyl alcohol. Iso-propyl alcohol is particularly preferable. Further, the total solid concentration of the coating liquid of the present invention is preferably 2 to 35%, and usually 5 to 30%. Further, the coating solution may contain a curing catalyst.

  Examples of the catalyst include acidic catalysts such as benzenesulfonic acid, its amine salt and its ammonium salt, naphthalenesulfonic acid derivative, its amine salt and its ammonium salt, phosphoric acid, its amine salt and its ammonium salt. Specifically, dodecylbenzenesulfonic acid and its amine salt, ammonium salt, dinonylnaphthalenesulfonic acid and its amine salt, ammonium salt, p-toluenesulfonic acid and its amine salt, ammonium salt, phosphoric acid, dihydrogen phosphate Examples thereof include ammonium, ammonium monohydrogen phosphate, catalyst 500 (manufactured by Mitsui Cyanamid), catalyst 600 (same), catalyst 4040 (same), and the like. A neutral catalyst such as magnesium chloride can also be used.

  Furthermore, if necessary, it is optional to add various known inorganic and organic additives such as an antistatic agent, a slipping agent and an antiblocking agent to the coating layer as long as the object of the present invention is not impaired.

  In this manner, a coating layer containing an organic compound containing two or more hydroxyl-reactive functional groups and an organic resin containing a hydroxyl group as essential components is formed on the substrate. As a method for forming the coating layer on the substrate, a method of coating the substrate with an aqueous solution is usually employed as described above. The coating method is not limited, but an optimal method may be selected depending on the coating amount and viscosity of the coating liquid to be used. A reverse roll coating method, a roll knife coating method, a die coating method, or the like may be employed.

The drying and heat treatment conditions during coating depend on the coating thickness and equipment conditions, but they can be sent immediately to the stretching process in the perpendicular direction without any drying process and dried in the preheating zone or stretching zone of the stretching process. preferable. In such a case, it is normally performed at about 50 to 250 ° C. If necessary, before forming the oxygen gas barrier layer, the substrate film may be subjected to corona discharge treatment, other surface activation treatment or an anchor treatment using a known anchor treatment agent.
Although the thickness of the coating layer of the present invention varies depending on the base material layer, the minimum thickness for exhibiting the gas barrier property is good, and it is usually 1 μm or less in terms of transparency, handleability, and economical efficiency. Is preferable.

  It is necessary to laminate an inorganic thin film layer on the laminate of such a coating layer. Metals such as aluminum and titanium, oxides such as silicon, aluminum, titanium, zirconium, tin, and magnesium, nitrides, fluorides alone, or a composite thereof can be vacuum-deposited, sputtering, plasma vapor deposition It is formed by a vacuum process such as (CVD method) or a wet process such as a sol-gel method. Among them, the method of vacuum-depositing a composite of alumina and silica is preferable from the viewpoints of the gas barrier property and economic efficiency targeted by the present invention.

  Since the gas barrier laminate film of the present invention is usually used as a packaging material, a heat sealable resin layer called a sealant is formed on an inorganic thin film layer. The heat-sealable resin layer is usually formed by an extrusion lamination method or a dry lamination method. The thermoplastic polymer for forming the heat-sealable resin layer may be any one that can sufficiently exhibit sealant adhesive properties, such as polyethylene resins such as HDPE, LDPE, and LLDPE, PP resin, and ethylene-vinyl acetate copolymer. , Ethylene-α-olefin random copolymer, ionomer resin, and the like can be used.

  According to the present invention, oxygen barrier properties, water vapor barrier properties, flexibility, moisture resistance, and heat resistance are extremely excellent, and dioxin and hydrogen chloride gas are not included in incineration exhaust gas. And effective film can be provided.

  Hereinafter, the present invention will be described in detail by way of examples. The film properties obtained in each example were measured and evaluated by the following methods.

1) Measurement of oxygen barrier The oxygen permeability of the prepared film was measured using an oxygen permeability measuring device (OX-TRAN100 manufactured by Modern Controls) under the condition of 85% RH.

2) Measurement of water vapor barrier The water vapor permeability of the prepared film was measured using a measuring device (PARMATRAN-W) manufactured by MOCON, USA under the conditions of 40 ° C. and 90% RH.

3) Gelbo treatment As a flexible evaluation, a gelbo flex tester (manufactured by Rigaku Corporation) was used. Twist treatment was performed 50 times under the conditions of 20 ° C., 65% RH, 50 twists / minute.

(Example 1)
[Preparation of coating solution]
While stirring 920 g of water, 80 g of polyvinyl alcohol resin having no modification and a saponification degree of 98.5 mol% was gradually added. It heated to 90 degreeC, the polyvinyl alcohol resin was melt | dissolved completely, and 8% aqueous solution of polyvinyl alcohol resin was prepared. Next, 1000 g of this polyvinyl alcohol resin aqueous solution, methylated melamine M-30W (104 g manufactured by Sumitomo Chemical Co., Ltd., 756 g water, and 140 g isopropyl alcohol were mixed to prepare a coating solution having a solid content concentration of 8%.
[Evaluation of coating on film]
A PET having an intrinsic viscosity of 0.62 (30 ° C., phenol / tetrachloroethane = 60/40) is pre-crystallized and then dried, and is extruded at 280 ° C. using an extruder having a T die, and a drum having a surface temperature of 40 ° C. It was rapidly cooled and solidified to obtain an amorphous sheet. Next, the obtained sheet was stretched 4.0 times at 100 ° C. in the longitudinal direction between the heating roll and the cooling roll. And the said coating liquid was apply | coated to the single side | surface of the obtained uniaxially stretched film so that the resin solid content thickness before extending | stretching might be 0.2 micrometer by the fountain bar coat method. Dried to a tenter, preheated at 100 ° C, stretched 4.0 times transversely at 120 ° C, heat treated at 225 ° C with 6% transverse relaxation, and 12 µm thick biaxially stretched polyester A film was obtained.

Next, in order to deposit on this coated surface, electron beam deposition is performed using particulate SiO ₂ (purity 99.9%) and Al ₂ O ₃ (purity 99.9%) of about 3 mm to 5 mm as a deposition source. By the method, a mixed gas barrier layer of aluminum oxide and silicon dioxide was formed on the obtained coated film. The vacuum layer contains an unwinding part, a coating part, and a winding part, and can be continuously deposited on the film. The pressure during vapor deposition was adjusted to 1.0 × 10 ⁻⁴ Torr. SiO ₂ and Al ₂ O ₃ were divided into two without mixing. An electron gun (hereinafter referred to as an EB gun) was used as a heating source, and two types of raw materials were heated in a time division manner. At that time, the emission current of the EB gun was set to 1.2 A, and the heating ratio of SiO ₂ to Al ₂ O ₃ was heated at 1: 2. The film feed rate was 130 m / min, and a film having a thickness of 150 mm (angstrom) was formed. Moreover, the temperature of the roll for cooling the film at the time of vapor deposition was adjusted to -10 degreeC. Next, a polyurethane adhesive (TM-590 /, manufactured by Toyo Morton Co., Ltd.) was applied to the vapor deposition surface of the film at about 3 μm, heat treated at 80 ° C., and then a low-density polyethylene film (manufactured by Toyobo: L6102 / thickness 40 μm) ) Was dry laminated at a nip pressure of 490 kPa on a metal roll heated to 80 ° C. to obtain a laminated film.
The film was measured for 85% RH oxygen permeability, water vapor permeability, and 85% RH oxygen permeability after gelbo treatment. The results are shown in Table 1.

(Examples 2 to 6, Comparative Examples 2 and 3)
A sample was prepared and evaluated in the same procedure as in Example 1 except that the coating solution was changed as shown in Table 1. The results are shown in Table 1.

(Comparative Example 1)
Samples were prepared and evaluated in the same procedure as in Example 1 without coating. The results are shown in Table 1.

  According to the present invention, flexibility, moisture resistance, heat resistance, particularly oxygen barrier properties and water vapor barrier properties are excellent, and incineration exhaust gas does not contain dioxin and hydrogen chloride gas, which has been a problem in recent years. It is possible to provide various packaging films that are effective against the above.

Claims (4)

  A coating layer containing an organic compound containing two or more hydroxyl-reactive functional groups and an organic resin containing a hydroxyl group as essential components is laminated on a substrate made of a polymer resin composition, and an inorganic thin film is further formed thereon. A gas barrier laminate film comprising a laminate of layers.   2. The gas barrier laminate film according to claim 1, wherein the organic compound containing a hydroxyl-reactive functional group is methylol melamine in which part or all of the methylol group is alkyl etherified.   The gas barrier laminate film according to claim 1 or 2, wherein the organic resin containing a hydroxyl group is a polyvinyl alcohol polymer.   4. The gas barrier laminate film according to claim 1, 2 or 3, wherein a coating layer having a weight ratio of an organic compound containing a hydroxyl-reactive functional group / an organic resin containing a hydroxyl group is larger than 20/80. .