Gas barrier coating agent, gas barrier coating layer, and laminate

Abstract

To provide a gas barrier coating agent using biomass that can increase a solid content concentration.SOLUTION: A gas barrier coating agent contains a carboxyl group-containing polysaccharide, a hydrolytic condensate of an alkoxysilane compound, an alcohol, a basic compound, and water. In the gas barrier coating agent, the total percentage of the carboxyl group-containing polysaccharide and the hydrolytic condensate of the alkoxysilane compound is preferably 3 mass% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a gas barrier coating agent, a gas barrier coating layer, and a laminate. [Background technology]

[0002] In packaging materials used for food, medicine, electronic parts, etc., coating agents with gas barrier properties that block gases such as oxygen and water vapor are used to protect the contents. From the viewpoint of environmental conservation, coating agents with gas barrier properties that utilize natural resources (biomass) are also known (Patent Documents 1-3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-334600 A [Patent Document 2] JP 2008-49606 A [Patent Document 3] International Publication No. 2011 / 118520 Summary of the Invention [Problem to be solved by the invention]

[0004] It has been found that the above-mentioned coating agents having gas barrier properties that utilize natural resources (biomass) have problems such as thickening and gelling of the coating agent when the solid content concentration is increased.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a gas barrier coating agent that utilizes biomass and is capable of increasing the solid content concentration.

[0006] Another object of the present invention is to provide a gas barrier coating layer formed from the gas barrier coating agent, and a laminate having the coating layer. [Means for solving the problem]

[0007] That is, the present invention relates to a gas barrier coating agent containing a polysaccharide having a carboxyl group, a hydrolysis condensate of an alkoxysilane compound, an alcohol, a basic compound, and water.

[0008] The present invention also relates to a gas barrier coating layer formed from the gas barrier coating agent.

[0009] The present invention also relates to a laminate having a substrate and the gas barrier coating layer. Effect of the Invention

[0010] Although the details of the mechanism of action of the gas barrier coating agent of the present invention are unclear, it is presumed as follows, however, the present invention is not limited to this mechanism of action.

[0011] The gas barrier coating agent of the present invention contains a polysaccharide having a carboxyl group, a hydrolysis condensate of an alkoxysilane compound, an alcohol, a basic compound, and water. It is presumed that the polysaccharide having a carboxyl group is neutralized with the basic compound to improve its solubility in alcohol and suppress gelation, thereby increasing the solid content concentration of the gas barrier coating agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The gas barrier coating agent of the present invention contains a polysaccharide having a carboxyl group, a hydrolysis condensate of an alkoxysilane compound, an alcohol, a basic compound, and water.

[0013] <Polysaccharides with carboxyl groups> The polysaccharide having a carboxyl group may be a known one, and examples thereof include polysaccharides (natural polysaccharides) that originally have a carboxyl group, such as pectin, alginic acid, and hyaluronic acid. The polysaccharide having a carboxyl group may be one in which at least a part of the functional groups (e.g., hydroxyl group, amino group, etc.) in the molecule of a polysaccharide such as starch, amylose, amylopectin, dextrin, glycogen, cyclodextrin, cellulose, agarose, inulin, glucomannan, chitin, or chitosan is chemically modified to introduce a carboxyl group. Among these, polysaccharides that originally have a carboxyl group are preferred from the viewpoint of increasing the biomass degree of the solid content contained in the gas barrier coating agent, and pectin is more preferred from the viewpoint of increasing the coating film strength such as water resistance. The polysaccharide having a carboxyl group may be used alone or in combination of two or more kinds.

[0014] <Hydrolysis and condensation products of alkoxysilane compounds> The hydrolysis condensate of the alkoxysilane compound may be any product obtained by hydrolysis and condensation of an alkoxysilane compound. Examples of the alkoxysilane compound include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, and tetrabutoxysilane; methyltrimethoxysilane, methyltriethoxysilane, methyltripoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, and isopropyltriethoxysilane. Trialkoxysilanes such as methoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, and 3,4-epoxycyclohexylethyltrimethoxysilane; dialkoxysilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, and diethyldiethoxysilane; and the like. Among these, tetraalkoxysilanes and trialkoxysilanes are preferred from the viewpoint of improving gas barrier properties. The alkoxysilane compounds can be used alone or in combination of two or more.

[0015] <Alcohol> The alcohol may be any known alcohol, for example, an alcohol having about 1 to 10 carbon atoms, but from the viewpoint of improving the drying property of the coating agent and the stability of the hydrolysis condensate of the alkoxysilane compound, it is preferable to include a lower alcohol having 2 to 4 carbon atoms, such as ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, etc. The alcohol may be used alone or in combination of two or more kinds.

[0016] <Basic compounds> The basic compound may be a known one, for example, an inorganic basic compound such as sodium hydroxide or potassium hydroxide; an organic basic compound such as ammonia, methylamine, ethylamine, monoethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, diethanolamine, N-methyldiethanolamine, triethanolamine, morpholine, N-methylmorpholine, or N-ethylmorpholine. Among these, ammonia is preferred from the viewpoint of improving the water resistance of the gas barrier coating layer. The basic compound may be used alone or in combination of two or more kinds.

[0017] The total ratio of the polysaccharide having a carboxyl group and the hydrolysis condensate of the alkoxysilane compound in the gas barrier coating agent can be 3% by mass or more by including at least a basic compound in the gas barrier coating agent.The total ratio of the polysaccharide having a carboxyl group and the hydrolysis condensate of the alkoxysilane compound in the gas barrier coating agent is preferably 4% by mass or more, more preferably 5% by mass or more, from the viewpoint of improving the water resistance and barrier property of the gas barrier coating layer, and is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, from the viewpoint of improving the water resistance and barrier property of the gas barrier coating layer.

[0018] The mass ratio of the polysaccharide having a carboxyl group to the hydrolysis condensate of the alkoxysilane compound (polysaccharide having a carboxyl group / hydrolysis condensate of the alkoxysilane compound) is preferably 0.2 or more, and more preferably 0.4 or more, from the viewpoint of improving the water resistance and barrier properties of the gas barrier coating layer, and is preferably 1.2 or less, more preferably 0.9 or less, and even more preferably 0.7 or less, from the viewpoint of improving the water resistance and barrier properties of the gas barrier coating layer.

[0019] The proportion of the alcohol in the gas barrier coating agent is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoint of improving the coatability, storage stability, etc. of the gas barrier coating agent and preventing precipitation of the hydrolysis condensate of the alkoxysilane compound, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of improving the coatability, storage stability, etc. of the gas barrier coating agent and preventing gelation of the polysaccharide having a carboxyl group. The alcohol also includes alcohol generated by hydrolysis of the alkoxysilane compound.

[0020] The proportion of water in the gas barrier coating agent is preferably 45% by mass or more, more preferably 50% by mass or more, from the viewpoint of adjusting the viscosity so that the gas barrier coating agent has good handleability, and is preferably 75% by mass or less, more preferably 70% by mass or less, from the viewpoint of preventing gelation of polysaccharides having carboxyl groups and preventing precipitation of hydrolysis condensation products of alkoxysilane compounds. The water also includes water used in the hydrolysis condensation reaction of alkoxysilane compounds.

[0021] The gas barrier coating agent may contain additives such as disaccharides such as sucrose; polysaccharides other than polysaccharides having a carboxyl group, such as starch, amylose, amylopectin, dextrin, glycogen, cyclodextrin, cellulose, agarose, inulin, glucomannan, chitin, and chitosan; gas barrier resins such as polyvinyl alcohol resins and ethylene-vinyl alcohol resins; ultraviolet absorbers, antistatic agents, leveling agents, defoamers, preservatives, and fillers, as necessary.

[0022] In the solid content of the gas barrier coating agent (excluding the basic compound), the total proportion of the polysaccharide having a carboxyl group and the hydrolysis condensate of the alkoxysilane compound is preferably 50 mass% or more, more preferably 60 mass% or more, and even more preferably 70 mass% or more.

[0023] The gas barrier coating agent preferably has a biomass ratio of 25% or more, more preferably 30% or more, and even more preferably 40% or more, in the solid content contained in the gas barrier coating agent (excluding the basic compound).

[0024] The gas barrier coating agent contains the basic compound, and from the viewpoint of suppressing gelation of polysaccharides having carboxyl groups, the pH is preferably 2.0 or higher, and more preferably 2.5 or higher, and from the viewpoint of improving the storage stability of the gas barrier coating agent, the pH is preferably 8.0 or lower, and more preferably 7.0 or lower.

[0025] From the viewpoint of coatability, the gas barrier coating agent preferably has a viscosity (initial viscosity after production) of 1 to 1000 mPa·s, more preferably 5 to 500 mPa·s, and even more preferably 10 to 200 mPa·s.

[0026] The method for preparing the gas barrier coating agent is not particularly limited. For example, the above-mentioned components may be added in order or simultaneously and mixed with a stirrer or disperser.

[0027] <Gas barrier coating layer, laminate> The gas barrier coating layer of the present invention is a dry film formed from the gas barrier coating agent. The laminate of the present invention has a substrate and the gas barrier coating layer. The laminate is usually obtained by applying the gas barrier coating agent to the substrate. The method of applying the gas barrier coating agent is not particularly limited, and examples of the method include coating methods using various coating devices such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, a die coater, and a spray coater.

[0028] The coating amount (dry film thickness) of the gas barrier coating layer is usually 0.1 g / m 2 It is preferable that the content is 0.5 g / m or more. 2 More preferably, it is 10 g / m or more. 2 It is preferable that the thickness is less than 5 g / m 2 It is more preferable that:

[0029] Examples of the substrate include base paper such as pulp that has been conventionally used in paper barrier materials, various plastic films made of polyolefin, modified polyolefin, polyester, nylon, polystyrene, etc. that have been conventionally used in flexible packaging, and composite films made of two or more of these. The substrate may be subjected to metal vapor deposition treatment, corona discharge treatment, surface coating treatment, etc.

[0030] In addition to the above-mentioned substrate and gas barrier coating layer, the laminate may further include a thermoplastic resin layer that enables heat sealing, a printed layer, a protective layer, etc. In this case, each layer may be laminated by melt extrusion or by using an adhesive. EXAMPLES

[0031] The present invention will be described below with reference to examples, but the present invention is not limited to these.

[0032] <Preparation Example 1> <Preparation of an aqueous solution of polysaccharides having carboxyl groups> 90 parts of ion-exchanged water was added to 10 parts by mass of a pectin mixture (product name "LM-100AS-HP", manufactured by Sansho Co., Ltd.), and the mixture was stirred at 90°C for 1 hour to obtain an aqueous pectin solution (pectin concentration 5.5% by mass, sucrose concentration 4.5% by mass).

[0033] <Preparation of aqueous solution of polyvinyl alcohol> 90 parts by mass of ion-exchanged water was added to 10 parts by mass of polyvinyl alcohol (trade name "PVA-105", manufactured by Kuraray), and the mixture was stirred at 95°C for 1 hour to obtain an aqueous PVA solution (solid content 10% by mass).

[0034] <Preparation of hydrolysis condensation products of alkoxysilane compounds (1)> 41.7 parts by mass of ion-exchanged water was added to 43.3 parts by mass of tetraethoxysilane (product name "High-purity ethyl orthosilicate", manufactured by Tama Chemical Industry Co., Ltd.), and 14.7 parts by mass of ethanol and 0.3 parts by mass of 1 N hydrochloric acid as a hydrolysis catalyst were added with stirring, followed by heating at 50°C for 1 hour to obtain an aqueous solution of tetraethoxysilane (TEOS) hydrolysis condensate (solid content 12.5% ​​by mass).

[0035] <Preparation of hydrolysis condensation products of alkoxysilane compounds (2)> 47.9 parts by mass of ion-exchanged water was added to 37.1 parts by mass of methyltrimethoxysilane (manufactured by Tama Chemicals Co., Ltd.), and 14.7 parts by mass of ethanol and 0.3 parts by mass of 1 N hydrochloric acid as a hydrolysis catalyst were added with stirring, followed by heating at 50°C for 1 hour to obtain an aqueous solution of methyltrimethoxysilane (MTMS) hydrolysis condensate (solid content 12.5% ​​by mass).

[0036] <Example 1> <Production of gas barrier coating agent> 30 parts by mass of the above pectin aqueous solution, 32 parts by mass of the above TEOS hydrolysis condensate aqueous solution, 20 parts by mass of ethanol, 1.5 parts by mass of ammonia water (25%), and 16.5 parts by mass of ion-exchanged water were mixed and stirred at room temperature for 10 minutes to produce the gas barrier coating agent of Example 1. The pH of the gas barrier coating agent was 5.1.

[0037] <Preparation of Laminate Having Gas Barrier Coating Layer> The gas barrier coating agent obtained above was applied to a polypropylene film (product name "P-2161", manufactured by Toyobo Co., Ltd.) using a No. 6 wire bar, dried using a dryer, and then aged at 60°C for one day to form a gas barrier coating layer (coating amount of about 0.6 g / m 2 ) was formed to prepare a laminate having a gas barrier coating layer.

[0038] <Examples 2-6, Comparative Examples 1-3> According to the formulations in Table 1, the gas barrier coating agents of the Examples and Comparative Examples were produced and laminates having a gas barrier coating layer were prepared by the same operations as in Example 1. However, the gas barrier coating agent of Comparative Example 1 gelled, so that a laminate having a gas barrier coating layer could not be produced.

[0039] The laminates having the gas barrier coating layer obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 1.

[0040] <Evaluation of gas barrier properties under high humidity conditions> The laminate having the gas barrier coating layer obtained above was left for 72 hours in an atmosphere of 25°C and 90% RH, and then the oxygen transmission rate (OTR value) (unit: (cc / m)) was measured using an oxygen transmission rate measuring device (manufactured by Mocon, product name "OX-TRAN1 / 50") in accordance with JIS 7126 B method. 2 The measurements were performed at 25°C and in an atmosphere of 90% RH. 2The passing criteria was 100 / day·atm or less.

[0041] <Water resistance evaluation> The coating layer surface of the laminate having the gas barrier coating layer obtained above was rubbed with a cotton swab moistened with water, and evaluated according to the following evaluation criteria. ○: It takes 4 or more strokes for the coating to melt or peel off. ×: The coating film melts or peels off within 3 strokes.

[0042] [Table 1]

Claims

1. The composition contains a polysaccharide having a carboxyl group, a hydrolysis condensate of an alkoxysilane compound, an alcohol as a solvent, a basic compound, and water, A gas barrier coating agent (not including cellulose) characterized in that the proportion of the alcohol is 15% by mass or more and 60% by mass or less.

2. A method for producing a cellulose ester polymer comprising the steps of: (a) preparing a cellulose ester polymer having a carboxyl group; (b) preparing a hydrolysis condensate of an alkoxysilane compound; (c) preparing an alcohol solvent; (d) preparing a basic compound; and (e) preparing water; A gas barrier coating agent (not including cellulose) characterized in that the proportion of the alcohol is 20% by mass or more and 60% by mass or less.

3. 3. The gas barrier coating agent according to claim 1, wherein the total proportion of the carboxyl group-containing polysaccharide and the hydrolysis condensate of the alkoxysilane compound in the gas barrier coating agent is 3 mass % or more.

4. 4. The gas barrier coating agent according to claim 1, wherein the polysaccharide having a carboxyl group is pectin.

5. 5. The gas barrier coating agent according to claim 1, wherein the solid content contained in the gas barrier coating agent has a biomass ratio of 25% or more.

6. A gas barrier coating layer formed from the gas barrier coating agent according to any one of claims 1 to 5.

7. A laminate comprising a substrate and the gas barrier coating layer according to claim 6.

8. 8. The laminate according to claim 7, wherein the substrate is a base paper or a plastic film.

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