JP2013144791A - Aqueous coating liquid, and multi-layered structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating liquid, obtainable of a gas barrier layer excellent in transparency, gas barrier property and adhesiveness to a hydrophobic anchor coat layer by applying it onto a plastic substrate material and drying.SOLUTION: This aqueous coating liquid includes (A) a polyvinyl alcohol-based resin as a main component and (B) an ethylene oxide adduct of an acetylene glycol-based compound expressed by general formula (1) [wherein, Rand Rare each independently 4-10C alkyl; Rand Rare each independently 1-3C alkyl; (m) and (n) are each independently an integer of ≥0; and the sum of (m) and (n) is 1 to 8].

Description

  The present invention relates to an aqueous coating liquid containing a polyvinyl alcohol-based resin as a main component, and more specifically, an aqueous coating liquid capable of forming a gas barrier layer by coating and drying on a substrate surface such as plastic, and The present invention relates to a multilayer structure obtained by coating and drying such an aqueous coating liquid on the surface of a substrate.

  As a method for imparting an oxygen gas barrier property to a molded article such as a plastic film, sheet, bottle, or cup, an aqueous solution of polyvinyl alcohol resin (hereinafter abbreviated as PVA resin) is applied and dried, and then a substrate is obtained. A technique for forming a gas barrier layer on the surface is useful.

However, PVA resin, which is a hydrophilic resin, has poor affinity for hydrophobic resin base materials such as polyolefin resin and polyester resin, and when a coating layer is formed directly on these base materials, interlayer adhesive strength is increased. Is insufficient. In such a case, it is useful to provide an anchor coat layer between the substrate and the surface layer, and various anchor coat agents have been proposed. (For example, refer to Patent Document 1.)
Especially, the anchor coat agent which has polyethyleneimine as a main component is widely used from the outstanding adhesiveness with respect to PVA-type resin.

Japanese Patent Application Laid-Open No. 2004-243763

However, the anchor coat agent mainly composed of polyethyleneimine has strong adhesiveness,
There is no problem when the anchor coat layer and the gas barrier layer are continuously formed. However, both processes are discontinuous, and handling becomes difficult when the anchor coat layer needs to be wound once after forming the anchor coat layer.
Hydrophobic anchor coating agents represented by polyurethane resins are known as anchor coating agents with relatively low tack suitable for such usage, but hydrophobic agents that can provide sufficient adhesion to PVA resins. There is no known anchor coating agent, and no PVA-based resin coating solution that can provide good adhesion to the hydrophobic anchor coating layer has been found.

  That is, the present invention aims to provide an aqueous coating liquid containing a PVA-based resin as a main component and capable of obtaining a gas barrier layer having excellent interlayer adhesion to a hydrophobic anchor coat layer. To do.

In the present invention, as a result of intensive studies in view of the above circumstances, an aqueous coating liquid obtained by blending an ethylene oxide adduct (B) of an acetylene glycol compound with a PVA resin (A) as a main component. The inventors have found that the object of the invention can be achieved and completed the present invention.
This is because the wettability of the aqueous coating liquid to the coated surface is improved by blending the ethylene oxide adduct (B) of the acetylene glycol compound with the PVA resin (A). As a result, the hydrophobic anchor coat It is presumed that the adhesion with the layer was improved and good adhesion was obtained.

  The aqueous PVA-based resin coating liquid of the present invention can be suitably used as a coating liquid for forming a gas barrier layer for plastic films, sheets, or various molded products, and also has an interlayer adhesive property for a hydrophobic anchor coat layer. Therefore, the range of selection of the anchor coating agent is widened. .

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.
Hereinafter, the present invention will be described in detail.

The aqueous coating liquid of the present invention is an aqueous coating liquid comprising a PVA resin (A) as a main component and an ethylene oxide adduct (B) of an acetylene glycol compound added thereto.
Hereinafter, each will be described in order.

[PVA resin (A)]
First, the PVA resin (A) used in the present invention will be described.
The PVA resin (A) is a resin mainly composed of a vinyl alcohol structural unit obtained by saponification of a polyvinyl ester resin obtained by copolymerizing a vinyl ester monomer. Consists of alcohol structural units and vinyl ester structural units.
Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, versatic. Although vinyl acid acid etc. are mentioned, vinyl acetate is preferably used economically.

The average degree of polymerization (measured in accordance with JIS K6726) of the PVA-based resin (A) used in the present invention is usually 100 to 3000, particularly 200 to 1000, and more preferably 300 to 600.
If the average degree of polymerization is too small, the coating strength tends to be insufficient. If the average degree of polymerization is too large, the viscosity of the aqueous coating solution is increased, the coating property is decreased, and drying requires a high temperature and a long time. Tend to be.

The degree of saponification (measured in accordance with JIS K6726) of the PVA resin (A) used in the present invention is usually 80 to 100 mol%, particularly 90 to 99.9 mol%, particularly 98. Those of ˜99.9 mol% are preferably used.
If the degree of saponification is too low, water solubility is lowered, and it becomes difficult to obtain a good aqueous coating solution. Moreover, when a high oxygen gas barrier property is requested | required for the coating film by the aqueous | water-based coating liquid of this invention, it is preferable to use a saponification degree 99 mol% or more.

  In the present invention, as the PVA-based resin (A), various monomers are copolymerized at the time of producing the polyvinyl ester-based resin and saponified, and various functionalities are obtained by post-modifying unmodified PVA. Various modified PVA-based resins into which groups are introduced can be used.

  Monomers used for copolymerization with vinyl ester monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, 3-buten-1-ol, 4-pentene. Derivatives such as hydroxy group-containing α-olefins such as -1-ol, 5-hexen-1-ol, and 3,4-dihydroxy-1-butene and acylated products thereof, acrylic acid, methacrylic acid, crotonic acid, maleic acid , Unsaturated acids such as maleic anhydride and itaconic acid, its salts, monoesters or nitriles such as dialkyl esters, acrylonitrile and methacrylonitrile, amides such as diacetone acrylamide, acrylamide and methacrylamide, ethylene sulfonic acid, allyl Such as sulfonic acid, methallylsulfonic acid, etc. Refin sulfonic acids or salts thereof, alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerin monoallyl ether, 3 Vinyl compounds such as 1,4-diacetoxy-1-butene, substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate, vinylidene chloride, 1,4-diacetoxy-2-butene, and vinylene carbonate. .

In addition, PVA resins having a functional group introduced by a post-reaction include those having an acetoacetyl group by reaction with diketene, those having a polyalkylene oxide group by reaction with ethylene oxide, reaction with an epoxy compound, etc. Examples thereof include those having a hydroxyalkyl group or those obtained by reacting an aldehyde compound having various functional groups with PVA.
The content of the modified species in the modified PVA resin, that is, the constituent units derived from various monomers in the copolymer, or the functional group introduced by the post-reaction is largely different depending on the modified species. Although it cannot say, it is 1-20 mol% normally, and especially the range of 2-10 mol% is used preferably.

Among these various modified PVA resins, in the present invention, the PVA resin having a structural unit having a 1,2-diol structure in the side chain represented by the following general formula (2) is a stable aqueous coating solution. It is preferably used in that it is excellent in the properties and a coating film excellent in transparency is obtained.
In the general formula (2), R ⁵ , R ⁶ , and R ⁷ each independently represent a hydrogen atom or an organic group having 1 to 3 carbon atoms, X represents a single bond or a bonded chain, and R ⁸ , R 7 ⁹ and R ¹⁰ each independently represent a hydrogen atom or an organic group having 1 to 3 carbon atoms.

Among them, R ^{5 to} R ⁷ and R ^{8 to} R ¹⁰ in the 1,2-diol structural unit represented by the general formula (2) are all hydrogen atoms, and X is a single bond. A PVA resin having a structural unit represented by ') is most preferred.

In addition, R ^{5 to} R ⁷ and R ^{8 to} R ¹⁰ in the structural unit represented by the general formula (2) may be an organic group as long as the resin properties are not significantly impaired. Examples of the organic group include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. May have a functional group such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group, if necessary.

Further, X in the 1,2-diol structural unit represented by the general formula (2) is most preferably a single bond in terms of thermal stability and stability under high temperature or acidic conditions. A bonded chain may be used as long as it does not inhibit the effects of the present invention. Examples of such a bonded chain include hydrocarbons such as alkylene, alkenylene, alkynylene, phenylene, and naphthylene (these hydrocarbons include fluorine, chlorine, bromine, etc. _other, -O of may be substituted by a _{halogen) -, - (CH 2 O} ) m -, - (OCH 2) m -, - (CH 2 O) m CH 2 -, - CO-, _{-COCO -, - CO (CH 2} ) m CO -, - CO (C 6 H 4) CO -, - S -, - CS -, - SO -, - SO 2 -, - NR -, - CONR-, -NRCO-, -CSNR-, -NRCS-, -NRNR-, _{HPO 4 -, - Si (OR} ) 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) 2 -, - OTi (OR) 2 -, - OTi (OR) ₂ O—, —Al (OR) —, —OAl (OR) —, —OAl (OR) O—, etc. (R is each independently an arbitrary substituent, preferably a hydrogen atom or an alkyl group, m is an integer of 1 to 5). Among them, an alkylene group having 6 or less carbon atoms, particularly a methylene group or —CH ₂ OCH ₂ — is preferable from the viewpoint of stability during production or use.

  A method for producing a PVA resin having a 1,2-diol structure in the side chain is not particularly limited, but (i) a copolymer of a vinyl ester monomer and a compound represented by the following general formula (3) is used. A method of saponification, (ii) a method of saponifying and decarboxylating a copolymer of a vinyl ester monomer and a compound represented by the following general formula (4), and (iii) a vinyl ester monomer and the following general formula A method of saponifying and deketalizing a copolymer with the compound represented by (5) is preferably used.

In the general formulas (3), (4) and (5), R ⁵ , R ⁶ , R ⁷ , X, R ⁸ , R ⁹ and R ¹⁰ are all the same as in the case of the general formula (1). . R ¹¹ and R ¹² are each independently a hydrogen atom or R ¹³ —CO— (wherein R ¹³ is an alkyl group having 1 to 6 carbon atoms). R ¹⁴ and R ¹⁵ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

As the methods (i), (ii), and (iii), for example, the method described in JP-A-2006-95825 can be used.
Among these, from the viewpoint of excellent copolymerization reactivity and industrial handleability, it is preferable to use 3,4-diasiloxy-1-butene as the compound represented by the general formula (3) in the method (i). In particular, 3,4-diacetoxy-1-butene is preferably used.

  The content of the 1,2-diol structural unit contained in the PVA resin (A) having a 1,2-diol structure in the side chain is usually 1 to 20 mol%, and further 2 to 10 mol%, Particularly, those having 3 to 8 mol% are preferably used. If the content is too low, it is difficult to obtain the effect of the side chain 1,2-diol structure. On the other hand, if the content is too high, the gas barrier property at high humidity tends to deteriorate significantly.

The content of the 1,2-diol structural unit in the PVA resin (A) is a ¹ H-NMR spectrum (solvent: DMSO-d6, internal standard: tetramethylsilane) of a completely saponified PVA resin. Specifically, from peak areas derived from hydroxyl protons, methine protons, and methylene protons in the 1,2-diol units, methylene protons in the main chain, hydroxyl protons linked to the main chain, etc. What is necessary is just to calculate.

  Further, the PVA resin (A) used in the present invention may be one kind or a mixture of two or more kinds. In that case, the above-mentioned unmodified PVA, unmodified PVA and general formula are used. PVA resin having the structural unit represented by (2), PVA resin having a structural unit represented by general formula (2) having different saponification degree, polymerization degree, modification degree, etc., unmodified PVA, or general formula A combination of a PVA resin having the structural unit represented by (2) and another modified PVA resin can be used.

[Acetylene glycol ethylene oxide adduct (B)]
Next, the ethylene oxide adduct (B) of the acetylene glycol compound used in the present invention will be described.

The ethylene oxide adduct (B) of the acetylene glycol compound is represented by the following formula (1).

R ¹ and R ² in the general formula (1) each independently represent an alkyl group having 4 to 10 carbon atoms, particularly preferably 4 to 8 carbon atoms, particularly preferably 5 to 7 carbon atoms. Preferably used. Specific examples include 2-methylpropyl group, butyl group, 3-methylbutyl group, pentyl group, 4-methylpentyl group, hexyl group, 5-methylhexyl group, 2-ethylhexyl group, and the like. Methylbutyl is preferably used.
R ³ and R ⁴ each independently represent an alkyl group having 1 to 3 carbon atoms. Specifically, a methyl group and an ethyl group are preferred, and a methyl group is particularly preferred.
R ¹ and R ² , and R ³ and R ⁴ may be the same or different, but those having the same structure are preferably used.

Moreover, n and m in Formula (1) are respectively independently an integer greater than or equal to 0, and the sum of m and n is 1-8. Among them, those having m + n of 2 to 7, particularly 3 to 6 are preferably used.
When the sum of m and n is too small or too large, the adhesion between the PVA resin layer and the anchor coat layer tends to be insufficient.
In addition, since the ethylene oxide adduct (B) of the acetylene glycol compound is usually produced by an addition reaction of ethylene oxide to the acetylene glycol compound, m and n in the general formula (1) are independently and precisely determined. It is difficult to control. Therefore, m, n, and m + n are obtained as average values.

Specific examples of the ethylene oxide adduct (B) of the acetylene glycol compound include those in which R ^{1 to} R ⁴ are the above-mentioned various alkyl groups.
Examples include ethylene oxide adducts of 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol in which R ¹ and R ² are 3-methylbutyl groups and R ³ and R ⁴ are methyl groups. it can.

[Water-based coating solution]
The aqueous coating liquid of the present invention comprises the PVA resin (A) described above as a main component and an ethylene oxide adduct (B) of an acetylene glycol compound.
The content of the ethylene oxide adduct (B) of the acetylene glycol compound in the aqueous coating solution of the present invention is usually 0.005 to 1% by weight, particularly 0.01 to 0.1% by weight. Preferably used.
Moreover, content with respect to PVA-type resin (A) of the ethylene oxide adduct (B) of the acetylene glycol type compound in this aqueous coating liquid is 0.05 to 5 weight% normally, Especially 0.1-1 A range of% by weight is preferably used.
If the blending amount of the ethylene oxide adduct (B) of the acetylene glycol compound is too small, the adhesion to the anchor coat layer tends to be insufficient, and conversely if too large, the ethylene oxide addition of the acetylene glycol compound is insufficient. The solubility and dispersibility of the product (B) in water may be reduced, and precipitates may be generated, and the gas barrier properties of the obtained gas barrier layer tend to be insufficient.

The ethylene oxide adduct (B) of the acetylene glycol-based compound is preferably used as a solution in order to improve handling properties such as transfer, weighing, and addition, and as a solvent at that time, water, methanol, isopropanol, A monohydric alcohol such as butanol, a polyhydric alcohol such as ethylene glycol, propylene glycol and glycerin, a polymer of polyhydric alcohol such as polyglycerol, and a mixed solvent thereof are preferably used.
The concentration at that time is not particularly limited, but is usually 20 to 60% by weight, and particularly preferably 30 to 50% by weight.

  In the aqueous coating solution of the present invention, it is a more preferable embodiment to further blend an ethylene glycol-propylene glycol block copolymer (C).

The ethylene oxide-propylene oxide block copolymer (C) can be represented, for example, by the following general formula (6), and x and y in the general formula (6) are x / y = 2/8. Those having a ratio of ˜8 / 2, particularly 3/7 to 7/3 are preferably used. Moreover, what has a polymerization degree of 400-8000 is used preferably.

  The ethylene oxide-propylene oxide block copolymer (C) is a nonionic surfactant as in the ethylene oxide adduct (B) of the acetylene compound described above, but the ethylene oxide-propylene oxide block copolymer ( Even when C) is used alone, the adhesiveness to the substrate which is the effect of the present invention cannot be sufficiently obtained. However, by blending the ethylene oxide-propylene oxide block copolymer (C), the appearance of the aqueous coating liquid is improved (suppressing the formation of insoluble matter), so that an ethylene oxide adduct of an acetylenic compound ( It is presumed that it functions as a compatibilizer between B) and the PVA resin (A).

The blending amount of the ethylene oxide-propylene oxide block copolymer (C) is usually 0.005 to 1% by weight in the aqueous coating solution as in the case of the ethylene oxide adduct (B) of the acetylene compound, particularly 0. 0.01 to 0.1% by weight, usually 0.05 to 5% by weight with respect to the PVA-based resin (A), and particularly preferably 0.1 to 1% by weight.
The content ratio of the ethylene oxide adduct (B) of acetylene glycol and the ethylene oxide-propylene oxide block copolymer (C) is usually from 8/2 to 2/8, particularly from 7/3 to 3/7. In particular, the range 6/4 to 4/6 is used.

  The aqueous coating liquid of the present invention contains a nonionic surfactant (C) other than the above-mentioned ethylene oxide adduct (B) of an acetylene glycol compound and an ethylene oxide-propylene oxide block copolymer (C). It is also possible to do. Specific examples of such nonionic surfactants include ethylene oxide adducts of acetylene alcohol, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene Ether compounds such as ethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether; polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, Sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene Ester compounds such as Teareto; silicon compound of the dimethylpolysiloxane; fluoroalkyl ester, and the like fluorine-containing compounds such as perfluoroalkyl carboxylic acid salt.

  In addition, the aqueous coating liquid of the present invention includes an antifoaming agent, a surfactant, an ultraviolet absorber, an antioxidant, a colorant, a fluorescent dye, an antiseptic, and an antifungal material within a range not impairing the effects of the present invention. A conventionally known additive such as an agent or a layered inorganic compound for further improving gas barrier properties may be blended. Further, it may contain an organic solvent other than water for the purpose of improving the wettability to the substrate or adjusting the drying speed, and specifically, an alcohol having 1 to 4 carbon atoms that is miscible with water. And ketones.

The concentration of the aqueous coating solution of the present invention is usually 0.1 to 30% by weight, particularly 1 to 20% by weight, particularly 5 to 15% by weight.
If the concentration is too high, bubbles generated when coating on the substrate are difficult to escape, workability during coating is reduced, and it is difficult to obtain a uniform coating layer. Conversely, if the concentration of the aqueous coating solution is too low, it may take a long time to dry or it may be difficult to obtain a coating layer with a desired thickness, which may necessitate multiple coatings. is there.

  As a method for producing the aqueous coating liquid of the present invention, a known method for preparing an aqueous liquid containing a plurality of water-soluble compounds can be employed. For example, (1) each aqueous solution is prepared and mixed. And (2) an ethylene oxide adduct (B) of an acetylene glycol compound and other additives in an aqueous solution of the PVA resin (A), and a method of mixing them.

[Base material / anchor coat layer]
The aqueous coating liquid of the present invention is applied to the surface of a substrate such as plastic and dried to form a gas barrier layer. Usually, an anchor coat layer is formed on the surface of the base material and coated thereon.
Such a plastic substrate is not particularly limited as long as it is a thermoplastic resin. If the aqueous coating liquid of the present invention can be applied, it is preferably a transparent resin when used for packaging purposes.
Specific examples of such thermoplastic resins include homopolymers such as polyethylene and polypropylene, block or random copolymers of α-olefins such as ethylene, propylene, 1-butene, 1-pentene and 1-hexene, and ethylene. Polyolefin resins such as vinyl acetate, ethylene and acrylic acid derivatives; Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; Nylon 6, nylon 66, nylon 11, nylon 610, nylon 6/66, MXDA nylon, etc. Polyamide-based resin; acrylic resin such as polymethyl methacrylate; polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-acrylonitrile-butadiene copolymer What polystyrene resins, and the like.

Examples of the shape of the plastic substrate include a film shape, a sheet shape, and various molded products such as bottles and cups.
In particular, in the case of a film having a wide application range as a packaging application, a known method can be used as its production method. Specifically, a solution casting method, a T-die method, a tubular method, a calendar method, etc. are appropriately employed. Is done. Further, for the purpose of improving mechanical properties and various properties, those subjected to stretching treatment are preferable.
Also, those plastic surfaces whose surfaces have been activated by discharge treatment such as corona treatment, plasma treatment, and glow discharge treatment, ionizing radiation treatment such as ultraviolet treatment and electron beam treatment, flame treatment, ozone treatment, etc. Preferably used.

  The thickness of the base material is not particularly limited, and a suitable material may be used according to the shape and purpose. However, in the case of the above-mentioned film shape, a range of usually 1 to 200 μm, particularly 5 to 100 μm is preferably used. .

In the laminate with the aqueous coating liquid of the present invention, a hydrophobic anchor coat layer is provided on the surface of the base film obtained as described above, and the aqueous coating liquid is coated thereon and dried. Thus, a gas barrier layer is formed. By providing such an anchor coat layer, the adhesion between the gas barrier layer and the substrate is improved.
The contact angle of water at 23 ° C. of the hydrophobic anchor coat layer is usually 65 to 120 degrees, and a range of 70 to 110 degrees is particularly preferably used.
Examples of the hydrophobic anchor coating agent used for forming such a hydrophobic anchor coat layer include, for example, polyester resins, polyurethane resins, polyacrylic resins, isocyanate resins, oxazoline resins, carbodiimide resins, and the like as main components. However, an anchor coating agent containing a polyurethane resin as a main component is preferably used as one that can achieve the effects of the present invention more remarkably.

  Such a polyurethane-based resin is produced by reacting a polyhydroxy compound and a polyisocyanate compound according to a conventional method, and a resin having a polar functional group such as a carboxyl group is preferably used.

The anchor coat layer is usually formed by applying a coating liquid containing an anchor coat agent on the surface of the substrate and drying it.
The anchor coating agent coating liquid may be either a solution type using an organic solvent as a main solvent or an aqueous emulsion type.
In addition, in such a coating solution, a crosslinking agent such as a silane coupling agent, inorganic fine particles, antifoaming agent, foaming agent, coating property improving agent, leveling agent, thickener, antistatic agent, antioxidant, Ultraviolet absorbers, dyes, pigments and the like can also be blended.

For applying the hydrophobic anchor coating agent, a known coating method can be appropriately used. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, a spray or a coating method using a brush can be used. After the application, a drying process is performed by a known method such as hot drying such as hot air drying or hot roll drying at a temperature of about 40 to 180 ° C. or infrared drying.
The thickness of the anchor coat is usually from 0.01 to 1 μm, and particularly preferably from 0.05 to 0.5 μm.

  The aqueous coating liquid of the present invention is applied to a substrate having a hydrophobic anchor coat layer on the surface thus obtained to form a gas barrier layer. The aqueous coating of the present invention is applied to such a substrate. As the method of coating the working liquid, gravure methods such as direct gravure method and reverse gravure method; roll coating methods such as two roll beat coating method and bottom feed three roll method, doctor knife method, die coating method, dip coating A known coating method such as a method or a bar coating method can be used.

  After the aqueous coating liquid of the present invention is applied to a substrate, moisture and other volatile components are removed by drying. The drying temperature at that time should be appropriately adjusted depending on the thickness of the coating layer, but is usually 10 to 200 ° C., and particularly preferably 20 to 150 ° C., particularly 30 to 120 ° C. . Further, the drying time is appropriately adjusted according to the above-mentioned drying temperature so that the volatile component is a predetermined amount or less, but is usually 0.1 to 120 minutes, and particularly 0.5 to 60. Done in minutes.

  The thickness of the gas barrier layer thus obtained is usually from 0.1 to 20 μm, particularly preferably from 0.5 to 15 μm, especially from 1 to 10 μm. If the thickness is too thin, sufficient gas barrier properties may not be obtained. On the other hand, if the thickness is too thick, the flexibility tends to be impaired when applied onto a flexible film substrate.

It is possible to further laminate other thermoplastic resins to the multilayer structure obtained in this manner. Furthermore, the surface of the gas barrier layer by the aqueous coating liquid of the present invention, or the interface of each layer, metal or It is also a preferred embodiment to provide a vapor deposition layer made of an inorganic component.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

Example 1
[Production of PVA resin (A1)]
A reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer was charged with 68.0 parts of vinyl acetate, 23.8 parts of methanol, and 8.2 parts of 3,4-diacetoxy-1-butene, and azobisisobutyronitrile. Was added in an amount of 0.3 mol% (compared with vinyl acetate), and the temperature was raised under a nitrogen stream while stirring to initiate polymerization. When the polymerization rate of vinyl acetate reaches 90%, m-dinitrobenzene is added to complete the polymerization, and then unreacted vinyl acetate monomer is removed out of the system by blowing methanol vapor. A combined methanol solution was obtained.

  Next, the methanol solution was further diluted with methanol, adjusted to a concentration of 45%, charged into a kneader, and a 2% methanol solution of sodium hydroxide was added to the vinyl acetate structural unit in the copolymer while maintaining the solution temperature at 35 ° C And saponification was performed by adding 10.5 mmol with respect to 1 mol of the total amount of 3,4-diacetoxy-1-butene structural units. As saponification progressed, when saponified substances were precipitated and formed into particles, they were separated by filtration, washed well with methanol, and dried in a hot air drier to prepare the intended PVA resin (A1).

The saponification degree of the obtained PVA-based resin (A1) was 99.2 mol% when analyzed by the alkali consumption required for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene. . The average degree of polymerization was 450 when analyzed according to JIS K 6726. The content of the 1,2-diol structural unit represented by the general formula (1) is ¹ H-NMR (300 MHz proton NMR, d6-DMSO solution, internal standard substance: tetramethylsilane, 50 ° C.). It was 6 mol% when computed from the measured integral value.

[Manufacture of aqueous coating solution]
To 100 parts by weight of the 10% aqueous solution of the obtained PVA resin (A1), 2,5,8,11-tetramethyl-6-dodecyne-5,8- as an ethylene oxide adduct (B) of an acetylene glycol compound was added. Add ethylene oxide adduct of diol (m + n = 5) (B1) 0.05 part by weight, ethylene oxide-propylene oxide block copolymer (C) (x = 1000, y = 1000) 0.05 part by weight, The aqueous coating solution of the present invention was used.

[Production of multilayer structure]
A polyurethane anchor coat agent (“Olivein EL-530A / B” manufactured by Toyo Morton Co., Ltd.) is applied to a polypropylene film (thickness 40 μm) with a corona treatment on the surface so that the thickness after drying becomes 1 μm. And dried in a hot air drier set at 80 ° C. for 10 minutes to form an anchor coat layer.
The contact angle of water at 23 ° C. of the anchor coat layer was 85 degrees.
On the anchor coat layer, the aqueous coating solution is coated with a bar coater so that the thickness after drying is 3 μm, and dried in a hot air drier set at 100 ° C. for 10 minutes to obtain a multilayer structure. Got.

<Appearance of aqueous coating solution>
The appearance of the obtained aqueous coating solution was visually observed, and the uniformity was evaluated according to the following criteria. The results are shown in Table 1.
○: Insoluble matter is not recognized.
Δ: Slight insoluble matter is observed.
X: Insoluble matter is observed on the entire surface.

<Adhesiveness>
Cut the cellophane tape (Sekisui "No. 252", width 15 mm) to a length of 6 cm, attach it to the gas barrier layer, peel off the tape 1 cm from the end, and peel this part at an angle of about 90 ° to the film surface. It peeled off vigorously. The state after repeating this operation 10 times was visually observed, and the adhesion was evaluated according to the following criteria. The results are shown in Table 1.
○: The gas barrier layer did not peel at all.
(Triangle | delta): The frequency | count that the gas barrier layer peeled 1-2 times.
X: The number of times the gas barrier layer was peeled off was 3 times or more.

Example 2
In Example 1, the addition amount of the ethylene oxide adduct (B) of the acetylene glycol compound was 0.025 wt%, and the addition amount of the ethylene oxide-propylene oxide block copolymer (C) was 0.025 wt%. Except for the above, an aqueous coating solution and a multilayer structure were prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 1.

Example 3
In Example 1, ethylene oxide adduct of 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol (m + n = 5) was used without using ethylene oxide-propylene oxide block copolymer (C). ) An aqueous coating solution and a multilayer structure were prepared in the same manner as in Example 1 except that the addition amount of (B1) was changed to 0.1% by weight and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 1
In Example 1, an aqueous solution containing an ethylene oxide adduct (B) of an acetylene glycol compound and an ethylene oxide-propylene oxide block copolymer (C) was not mixed, and the aqueous solution was the same as in Example 1 A coating solution and a coating film were prepared and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 2
In Example 1, an ethylene oxide adduct of 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol (m + n = 11) was used as the ethylene oxide adduct (B) of an acetylene glycol compound. An aqueous coating solution and a coating film were prepared in the same manner as in Example 1 except that they were used, and evaluated in the same manner. The results are shown in Table 1.

（Ｂ）：アセチレングリコール系化合物のエチレンオキサイド付加物
（Ｃ）：エチレンオキサイド−プロピレンオキサイドブロック共重合体 [Table 1]

(B): Ethylene oxide adduct of acetylene glycol-based compound (C): Ethylene oxide-propylene oxide block copolymer

From the above results, the aqueous coating liquid in which the ethylene oxide adduct (B) of the acetylene glycol compound is blended with the PVA resin (A) of the present invention is used for the anchor coat layer containing a polyurethane resin as a main component. And showed good adhesion. Furthermore, in the aqueous coating liquid in which the ethylene oxide-propylene oxide block copolymer is blended, insoluble matters are not recognized, and it is possible to form a gas barrier layer having excellent appearance.

  Since the aqueous coating liquid of the present invention is excellent in transparency and gas barrier properties, a gas barrier layer excellent in adhesiveness with various anchor coat layers, particularly a hydrophobic anchor coat layer such as a polyurethane-based anchor coat, is obtained. The material of the anchor coat layer can be widened, and it is extremely useful industrially as a material that can easily give gas barrier properties to a plastic material.

Claims (6)

An aqueous coating liquid comprising a polyvinyl alcohol resin (A) as a main component and an ethylene oxide adduct (B) of an acetylene glycol compound represented by the following general formula (1).

[Wherein, R ¹ and R ² each independently represent an alkyl group having 4 to 10 carbon atoms, and R ³ and R ⁴ each independently represent an alkyl group having 1 to 3 carbon atoms. m and n are each independently an integer of 0 or more, and the sum of m and n is 1-8. ] The aqueous coating solution according to claim 1, wherein the content of the ethylene oxide adduct (B) of the acetylene glycol compound in the aqueous coating solution is 0.05 to 5% by weight with respect to the polyvinyl alcohol resin (A). The aqueous coating liquid according to claim 1 or 2, comprising an ethylene glycol-propylene glycol block copolymer (C). The aqueous coating liquid according to claim 3, wherein the content ratio of the acetylene glycol ethylene oxide adduct (B) and the ethylene glycol-propylene glycol block copolymer (C) is 8/2 to 2/8 (weight ratio). The aqueous coating liquid according to any one of claims 1 to 4, wherein the polyvinyl alcohol resin (A) is a polyvinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (2).

[Wherein R ⁵ , R ⁶ and R ⁷ each independently represents a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R ⁸ , R ⁹ and R ¹⁰ each independently represent hydrogen. Indicates an atom or an organic group. ] A multilayer structure obtained by applying the aqueous coating liquid according to any one of claims 1 to 5 to a hydrophobic anchor coat layer provided on the surface of a substrate and drying it.