JP2002188039A - Gas barrier coating composition and gas barrier film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the original transparency and high gas barrier properties of polyvinyl alcohol, and to provide a high gas barrier property with good adhesion without requiring an anchor layer even when the base material is a polyolefin such as polypropylene. To form a coating film having SOLUTION: It is composed of the following components A, B, C and D, and a weight ratio (A / B) of the component A and the component B is 100/10 to 100.
/ 100, a gas barrier coating composition. A: Polyvinyl alcohol. B: An alkoxysilane having an epoxy group represented by the following general formula (1). Embedded image C: Acid catalyst. D: Water or water to which a lower alcohol is added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-barrier coating resin composition for forming a coating film having excellent gas-barrier properties, and a gas-barrier film using the same to form a gas-barrier layer.

[0002]

2. Description of the Related Art Conventionally, a gas-barrier coating composition comprises the following components a to d, and a / (b
+ C) = 9/1 to 1/99 is known (JP-A-9-255910). a: Polyvinyl alcohol. b: A (partial) hydrolyzate of an alkoxysilane having an epoxy group, a (partial) condensate thereof, and a mixture thereof. c: (partial) hydrolyzate, (partial) condensate of an alkoxysilane having an amino group and / or an imino group, and a mixture thereof. d: Water as a solvent.

[0003] However, since the above publication is mainly used for conductive films, it is used as a base material.
It is a polycarbonate that is not common as a packaging material, and the adhesion to a substrate when a polyester such as PET or a polyolefin such as PP commonly used as a packaging material is not disclosed.

On the other hand, Japanese Patent Application Laid-Open No. 10-296929 discloses a gas barrier film in which an easy-adhesion layer and a polyvinyl alcohol resin layer are sequentially laminated on at least one surface of a thermoplastic resin film. It is described that the layer contains an amino group-containing silane coupling agent.

[0005] However, the film has an easily adhesive layer (anchor layer) between the substrate and the polyvinyl alcohol resin layer.
Need to be provided, the process becomes complicated, there is a problem not only in terms of cost, but also when the anchor layer is not provided, there is also a problem that the adhesion between the base material and the polyvinyl alcohol resin layer is not sufficient. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and maintains the original transparency and high gas barrier properties of polyvinyl alcohol, and the base material is a polyolefin such as polypropylene. Even if
It is an object of the present invention to be able to form a coating film having good adhesion and high gas barrier properties without requiring an anchor layer.

[0007]

That is, the present invention comprises the following components A, B, C, and D, and the weight ratio (A / B) of the components A and B is 100/10 to 100/100. It is intended to provide a gas barrier coating composition characterized by the above.

A: Polyvinyl alcohol. B: An alkoxysilane having an epoxy group represented by the following general formula (1).

[0009]

Embedded image (Wherein, R ¹ is an alkylene group having 1 to 4 carbon atoms, R ² and R ³ are alkyl groups having 1 to 4 carbon atoms, X is a glycidoxy group or an epoxycyclohexyl group, and n is 1 or 0) ) C: Acid catalyst. D: Water or water to which a lower alcohol is added.

The component B in the present invention may be a mixture of an alkoxysilane having an epoxy group and a (partly) hydrolyzate and / or (partly) condensate thereof.
Further, the preferred embodiment includes that the C component is acetic acid. Further, the component A contains a modified polyvinyl alcohol, the modified polyvinyl alcohol is a polyvinyl alcohol having a silyl group in a molecule, the content of the silyl group is 0.01 to 5 mol%, This includes that the modified polyvinyl alcohol is a carboxyl group-modified polyvinyl alcohol.

Further, the present invention provides a gas barrier film having a coating film of the gas barrier coating composition of the present invention, wherein the coating film of the gas barrier coating composition is a polyolefin substrate. What is provided above is included as a preferred embodiment thereof.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The gas barrier coating composition of the present invention basically comprises the following components A, B, C and D.

A: Polyvinyl alcohol. B: An alkoxysilane having an epoxy group represented by the following general formula (1).

[0014]

Embedded image (Wherein, R ¹ is an alkylene group having 1 to 4 carbon atoms, R ² and R ³ are alkyl groups having 1 to 4 carbon atoms, X is a glycidoxy group or an epoxycyclohexyl group, and n is 1 or 0) ) C: Acid catalyst. D: Water or water to which a lower alcohol is added.

As the component A in the present invention, commercially available polyvinyl alcohol can be used. The polyvinyl alcohol used as the component A preferably has a polymerization degree of 100 to 5000 and a saponification degree of 70% or more, similarly to the polyvinyl alcohol used in the conventional gas barrier coating composition. If the degree of polymerization is too low, the adhesion to the substrate tends to decrease, and if the degree of polymerization is too high, the viscosity becomes too high and the coating properties tend to deteriorate. On the other hand, if the saponification degree is too low, the gas barrier properties tend to be insufficient.

As the component A, either modified or unmodified may be used. As the modified polyvinyl alcohol,
For example, carboxyl group, silyl group, sulfonic acid group, amino group, phosphoric acid group, isocyanate group, oxazoline group, methylol group, nitrile group, acetoacetyl group, modified polyvinyl alcohol with a cationic group, for example,
Examples include block copolymers and graft copolymers modified with acryl, urethane, polyester, epoxy, polyethylene, polypropylene, and the like. These modified polyvinyl alcohols and unmodified polyvinyl alcohols may be used alone or in combination of two or more. can do.

As the polyvinyl alcohol used as the component A in the present invention, a polyvinyl alcohol having a silyl group in a molecule and a carboxyl group-modified polyvinyl alcohol can be used.

Here, having a silyl group in the molecule means having a silyl group in the middle or at the terminal of the molecular chain of polyvinyl alcohol. It is preferable that the silyl group is bonded to the polyvinyl alcohol by a non-hydrolyzable bond. There is no particular limitation on the position and distribution state. The silyl group means a reactive silyl group represented by the following formula (2). However, in the following formula (2), R ⁴ is hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkali metal or an alkaline earth metal, R ⁵ is an alkyl group having 1 to 10 carbon atoms, and m is 1 to 3
Is an integer.

[0019]

Embedded image

The content of the silyl group in the polyvinyl alcohol having a silyl group in the molecule is preferably 0.01 to 5 mol%, more preferably 0.1 to 5 mol%.
1.0 mol%, optimally 0.1-0.6 mol%. When the content of the silyl group exceeds 5 mol%, the viscosity of the obtained gas barrier coating composition increases, and the gelation easily occurs. Conversely, when the content of the silyl group is less than 0.01 mol%, When the drying conditions for forming a dried and cured coating film are relaxed, when the film is stored under high humidity, the adhesion to the substrate tends to be reduced.

The carboxyl group-modified polyvinyl alcohol has a carboxyl group in the molecule and includes, for example, vinyl ester monomers such as vinyl acetate, vinyl formate, vinyl propionate, vinyl versatate, and vinyl piperate. The body is converted to, for example, acrylic acid, methacrylic acid, (phthalic anhydride),
After copolymerization with an ethylenically unsaturated carboxylic acid such as (anhydride) itaconic acid, a saponified random copolymer can be suitably used.

The carboxyl group modification amount is preferably from 0.1 to 50 mol%, more preferably from 0.5 to 1 mol%.
0 mol%, optimally 0.5 to 5 mol%.

The alkoxysilane having an epoxy group represented by the above general formula (1) used as the component B in the present invention includes, for example, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, glycidoxymethyltrimethoxysilane. Propoxysilane, glycidoxymethyltributoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 2-glycidoxyethyltripropoxysilane, 2-glycidoxyethyltributoxysilane , 1-
Glycidoxyethyltrimethoxysilane, 1-glycidoxyethyltriethoxysilane, 1-glycidoxyethyltripropoxysilane, 1-glycidoxyethyltributoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- Glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane,
3-glycidoxypropyltributoxysilane, 2-glycidoxypropyltrimethoxysilane, 2-glycidoxypropyltriethoxysilane, 2-glycidoxypropyltripropoxysilane, 2-glycidoxypropyltributoxysilane, 1-glycidoxypropyltrimethoxysilane, 1-glycidoxypropyltriethoxysilane, 1-glycidoxypropyltripropoxysilane, 1-glycidoxypropyltributoxysilane,
(3,4-epoxycyclohexyl) methyltrimethoxysilane, (3,4-epoxycyclohexyl) methyltriethoxysilane, (3,4-epoxycyclohexyl) methyltripropoxysilane, (3,4-epoxycyclohexyl) methyltributoxy Silane, 2-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltripropoxysilane, 2- (3
4-epoxycyclohexyl) ethyltributoxysilane, 3- (3,4-epoxycyclohexyl) propyltrimethoxysilane, 3- (3,4-epoxycyclohexyl) propyltriethoxysilane, 3- (3,4-
Epoxy (cyclohexyl) propyltripropoxysilane, 3- (3,4-epoxycyclohexyl) propyltributoxysilane, 4- (3,4-epoxycyclohexyl) butyltrimethoxysilane, 4- (3,4-epoxycyclohexyl) butyltrisilane Ethoxysilane, 4
-(3,4-epoxycyclohexyl) butyltripropoxysilane, 4- (3,4-epoxycyclohexyl) butyltributoxysilane, diethoxy-3-glycidoxypropylmethylsilane and the like.

As the component B, one or more of the above-mentioned alkoxysilanes having an epoxy group can be used. Particularly preferred as the B component are 3-glycidoxypropyltrimethoxysilane, 2- (3,4
-Epoxycyclohexyl) ethyltrimethoxysilane.

The acid catalyst used as the component C in the present invention is not particularly limited as long as it can make the composition weakly acidic. Examples thereof include carboxylic acids such as formic acid, acetic acid, propionic acid and butyric acid. Acetic acid is preferred from the viewpoint of volatility. As the C component, one of the acid catalysts described above is used.
Species or two or more can be used.

The water (distilled water) in the component D is a solvent, and a lower alcohol can be added to the solvent and used.
This makes it easier to prevent the occurrence of pinholes when the coating film is dried. Examples of the lower alcohol to be added to water include methyl alcohol, ethyl alcohol, and isopropyl alcohol. When the lower alcohol and water are mixed, the mixing ratio is preferably 10/90 to 30/70 by weight (lower alcohol / water). If the amount of the lower alcohol is too small, pinholes are apt to be generated when the coating film is dried. Conversely, if the amount of the lower alcohol is too large, the coatability tends to deteriorate.

Next, the mixing ratio of the above components A, B, C, and D will be described.

The component A is a component serving as a base for obtaining gas barrier properties, and the component B is a component for improving the adhesion between the obtained coating film and the substrate. The mixing ratio of the component A and the component B is 100/10 to 100/10 in weight ratio (A / B).
0, preferably 100/40 to 100/60. If the compounding amount of the component A is too large (the compounding amount of the component B is too small), particularly when the substrate is a polyolefin, the adhesion between the coating film and the substrate is reduced, and the adhesion is maintained. Drying conditions may be limited. Conversely, if the amount of the component A is too small (the amount of the component B is too large), the gas barrier properties of the obtained coating film will be insufficient.

The component C is a component for improving the wettability to the substrate, and its mixing ratio is not particularly limited.
The amount is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the components. If the amount of the component C is too large, the coating environment is likely to be deteriorated due to acidic odor. If the amount of the component C is too small, wettability to the substrate is poor, and a uniform coating film is difficult to form.

The mixing ratio of the component D may be appropriately selected according to the coating conditions and the like, but it is preferable that the solid content of the obtained gas barrier coating composition is 1 to 20% by weight. Can be appropriately selected according to the coating method and the like. If the amount of the D component is too large, it is difficult to obtain a coating film having a required thickness, and if the amount of the D component is too small, the coatability tends to deteriorate.

In the present invention, since water is used as a solvent, a part of the alkoxysilane having an epoxy group as the component B is slowly hydrolyzed into a (partly) hydrolyzed product. May change,
In some cases, this hydrolyzate is further transformed into a (partially) condensate. Even when such a change occurs, the effect of the present invention can be similarly obtained. Therefore, the component B in the present invention may be a mixture of an alkoxysilane having an epoxy group and a (partly) hydrolyzate and / or (partly) condensate thereof.

The gas-barrier coating composition according to the present invention basically comprises the above-mentioned components A to D, but is not more than 10 parts by weight based on 100 parts by weight of the total of components A to D. In order to improve the coating properties within a range that does not impair the effects of the present invention, a thickener, an antifoaming agent, a curing catalyst, a wettability improver, a plasticizer, and the like can be added and used.

The gas barrier coating composition according to the present invention is applied to a substrate to form a gas barrier coating film.

The coating on the substrate may be performed, for example, by dip coating,
Conventional methods such as spray coating, flow coating, roll coating, bar coating, spin coating, and gravure coating can be used. The thickness of the coating film is 0.2 to 7 μm, desirably, so as to obtain a good gas barrier property without complicating the coating operation and maintaining the adhesion strength with the substrate at a practical level. 0.3-1.
Preferably it is 5 μm.

It is preferable that the drying and curing of the coated film after application is performed in a heated atmosphere at an atmospheric temperature exceeding 50 ° C. If the atmosphere temperature during the drying and curing is too low, the adhesive strength between the substrate and the coating film tends to decrease, particularly when the obtained gas barrier film is stored under high humidity. The upper limit of the ambient temperature during the drying and curing depends on the heat resistance of the substrate, but is generally about 120 ° C.

As the substrate, for example, a synthetic resin such as polyolefin such as polypropylene or polyester is preferable, and a film or sheet having a coating film formed of the gas barrier coating composition of the present invention on the substrate, or a film with this coating film A film or sheet obtained by further laminating a heat seal layer or another layer on a sheet or sheet can be suitably used for gas barrier packaging. In particular, the gas barrier coating composition according to the present invention can form a coating film with good adhesion on a substrate of polyolefin, particularly polypropylene, which is frequently used for packaging, and a film or sheet suitable for gas barrier packaging. Is easy to obtain.

[0037]

The present invention will be described in more detail with reference to the following examples.

[0038] Examples 1-2, Comparative Examples 1-2 PVA and (A ₁ component: polyvinyl alcohol manufactured by Kuraray Co., "Poval 105"), EPTMS (B component: glycidoxypropyltrimethoxysilane methyltrimethoxysilane) and acetic acid ( C component)
Using IPA and H ₂ O (D component: isopropyl alcohol and water), a gas barrier coating resin composition was prepared at the mixing ratio shown in Table 1.

First, PVA was converted to IPA / H ₂ O = 20/8.
0 (weight ratio) to make a 5% by weight solution, acetic acid was added to 100 g of this PVA solution at the mixing ratio shown in Table 1, and EPTMS was mixed at the mixing ratio shown in Table 1 and stirred to obtain a gas barrier property. A coating composition was prepared.

The obtained gas barrier coating composition was coated with an OPP (stretched polypropylene) film having a thickness of 20 μm (gas barrier property: 2000 ml / m ² · atm · da).
y) A bar coat was applied on the substrate at a thickness of about 1 μm at 80 ° C.
The coating film was dried and cured by holding for 15 seconds in an atmosphere of.
The following evaluation was performed using the obtained base material with a coating film.

The results are shown in Table 1. In addition, about Comparative Example 1, since wettability was bad and a coating film could not be formed, evaluation was not performed.

(1) Wettability When the composition was applied on a substrate, the condition was visually evaluated. The case where no repelling occurred was evaluated as ○, and the case where repelling occurred was evaluated as x.

(2) Transparency Evaluation was made by comparing the base material before the formation of the coating film and the base material with the coating film with the naked eye. The case where there was almost no difference in the transparency between the two was evaluated as ○, and the case where the substrate with the coating film was slightly inferior in transparency was evaluated as △.

(3) Gas Barrier Property Oxygen permeability was measured under an atmosphere of dry room temperature in an oxygen permeability measuring apparatus (“OX-TRANTWIN” manufactured by MOCON).
It measured using.

(4) Cellophane tape peeling A 1 mm length and width was applied to the coating surface of the obtained coated substrate with a knife.
Cuts are made at intervals, 100 grids are formed, and cellophane tape (trade name: Cellophane, manufactured by Nichiban Co., Ltd.) is pasted thereon. Was evaluated for adhesion. When the coating film was not peeled off, it was evaluated as ○, and when the coating film was peeled, it was evaluated as x.

(5) Adhesion A 25 μm-thick CPP was applied to the coating surface of the obtained coated substrate by dry lamination using a polyurethane-based adhesive.
(Unstretched polypropylene) Laminated film, 40
After aging at 48 ° C for 48 hours, cut into 15mm width,
The peel strength was determined by T-shaped peeling between the CPP film and the substrate with the coating. A sample having a peel strength of 490 mN / 15 mm or less was rated as “x”, and a substrate having a broken substrate and a peel strength of 1960 mN / 15 mm or more was rated as “○”.

(6) High Humidity Storage The laminated film on which the same dry lamination was performed as in the evaluation of the adhesion was left in an atmosphere at a temperature of 20 ° C. and a humidity of 90% RH for 2 weeks, and then cut to a width of 15 mm. The peel strength was determined by T-shaped peeling between the film and the substrate with the coating.
Those having a peel strength of 490 mN / 15 mm or less are designated as x,
The base material is broken and the peel strength is 1960m
A sample having a diameter of N / 15 mm or more was marked with a circle.

[0048]

[Table 1]

[0049]

The present invention has been described above, and has the following effects.

(1) It is possible to form a gas barrier coating film with good adhesion to a substrate of polyolefin such as polypropylene without an anchor layer. Since polypropylene is frequently used as a packaging material, a packaging material having a high gas barrier property is easily obtained.

(2) It is excellent in transparency and moisture resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 183/06 C09D 183/06 // C08L 23:06 C08L 23:06 (72) Inventor Satoshi Fukaya Tokyo 4-14-12 Koishikawa, Bunkyo-ku, Kyodo Printing Co., Ltd. (72) Inventor Yumiko Hagio 4-14-12, Koishikawa, Bunkyo-ku, Tokyo Kyodo Printing Co., Ltd.F-term (reference) 4F006 AA12 AB20 AB34 AB39 BA05 CA07 4F100 AH02A AH02H AH06A AH06H AK03B AK07 AK21A AL05A BA02 CC00A EH46 EH462 EJ08 EJ082 EJ86 EJ862 GB15 JD02A JL08A JL11 YY00A 4J038 CE021 DL052 GA06 GA15 HA156 JA19 JA37 JC34 KA07

Claims (9)

[Claims] 1. A composition comprising the following components A, B, C and D, wherein the weight ratio (A / B) of the components A and B is 100/10 to 100
/ 100, a gas barrier coating composition. A: Polyvinyl alcohol. B: An alkoxysilane having an epoxy group represented by the following general formula (1). Embedded image (Wherein, R ¹ is an alkylene group having 1 to 4 carbon atoms, R ² and R ³ are alkyl groups having 1 to 4 carbon atoms, X is a glycidoxy group or an epoxycyclohexyl group, and n is 1 or 0. ) C: Acid catalyst. D: Water or water to which a lower alcohol is added. 2. The method according to claim 1, wherein the component B is a mixture of an alkoxysilane having an epoxy group and a (partly) hydrolyzate and / or a (partly) condensate thereof.
The gas barrier coating composition according to item 1. 3. The gas barrier coating composition according to claim 1, wherein the C component is acetic acid. 4. The gas barrier coating composition according to claim 1, wherein the component A contains a modified polyvinyl alcohol. 5. The gas barrier coating composition according to claim 4, wherein the modified polyvinyl alcohol is a polyvinyl alcohol having a silyl group in a molecule. 6. The content of the silyl group is 0.01 to 5 mol%.
The gas barrier coating composition according to claim 5, wherein 7. The gas barrier coating composition according to claim 4, wherein the modified polyvinyl alcohol is a carboxyl group-modified polyvinyl alcohol. 8. A gas barrier film having a coating film of the gas barrier coating composition according to any one of claims 1 to 7. 9. The gas barrier film according to claim 8, wherein the coating film of the gas barrier coating composition is provided on a polyolefin substrate.