Coatings, films and laminated packaging materials

Abstract

A coating agent comprising: amine-modified polyvinyl alcohol; and at least one compound (A) selected from the group consisting of a compound (A1) represented by the following formula (1) and a compound (A2) represented by the following formula (2). 1 ~R 6 , R 11 ~R 18 Each R is independently any one of a carboxyl group, a sulfo group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom. 1 ~R 6 One of them is either a carboxyl group or a sulfone group, R 1 ~R 6 2 or 3 of them are hydroxyl groups. 11 ~R 18 One of them is either a carboxyl group or a sulfone group, R 11 ~R 18 Two or three of them are hydroxyl groups.

Description

Technical Field

[0001] The present invention relates to a coating agent, a coating film used as a gas barrier layer or the like, and a laminated packaging material having the coating film. Background Art

[0002] It is known that amine-modified polyvinyl alcohols such as vinyl alcohol-vinyl amine copolymers have high oxygen barrier properties as disclosed in Patent Document 1, and have excellent adhesiveness among polyvinyl alcohol-based resins, and can be coated on plastic films to form films without using a binder. Therefore, they are increasingly being used as gas barrier layers in food packaging applications.

[0003] Furthermore, it is conventionally known that, as disclosed in Patent Documents 2 and 3, for example, an inorganic layered compound is blended into a gas barrier layer containing a vinyl alcohol-vinylamine copolymer for the purpose of improving oxygen barrier properties under high humidity.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5669738

[0007] Patent Document 2: Japanese Patent No. 6592224

[0008] Patent Document 3: Japanese Patent Application Publication No. 2018-149779 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, since the basic skeleton of amine-modified polyvinyl alcohol is polyvinyl alcohol, it has low water resistance. Therefore, if water adheres to the coating film formed by amine-modified polyvinyl alcohol, or if a large amount of articles containing water are packaged, it is easy to peel off and swell, and loses its function as a packaging material. Therefore, in the food field, its use is limited to dry goods, cakes, etc. that do not contain much water and are not sterilized by boiling or steaming.

[0011] In addition, for example, in order to improve the water resistance of polyvinyl alcohol, the use of crosslinking agents such as titanium chelate, boric acid, epichlorohydrin, aldehydes, etc. has been studied. However, if these crosslinking agents are used in a coating agent containing amine-modified polyvinyl alcohol, the coating agent is prone to gelation, and it is also difficult to impart sufficient water resistance.

[0012] On the other hand, as disclosed in Patent Documents 2 and 3, when an inorganic layered compound is contained in a coating agent, oxygen barrier properties under high humidity are improved, but water resistance cannot be sufficiently imparted and transparency is also reduced.

[0013] Therefore, an object of the present invention is to provide a coating agent which improves the water resistance of a coating film formed from a coating agent containing amine-modified polyvinyl alcohol and which can maintain good gas barrier properties without peeling off the coating film even when used in various applications.

[0014] Methods for solving problems

[0015] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by blending a compound (A) having a specific structure into a coating agent containing amine-modified polyvinyl alcohol, thereby completing the following present invention. Specifically, the present invention provides the following [1] to

[22] .

[0016] [1] A coating agent comprising: an amine-modified polyvinyl alcohol; and at least one compound (A) selected from a compound (A1) represented by the following formula (1) and a compound (A2) represented by the following formula (2).

[0017]

[0018] In formula (1), R 1 ~R 6 are each independently a carboxyl group, a sulfo group, a hydroxyl group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom, and R 1 ~R 6 One of them is either a carboxyl group or a sulfone group, R 1 ~R 6 2 or 3 of them are hydroxyl groups. 11 ~R 18 are each independently a carboxyl group, a sulfo group, a hydroxyl group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom, and R 11 ~R 18 One of them is either a carboxyl group or a sulfone group, R 11 ~R 18 Two or three of them are hydroxyl groups.

[0019] [2] The coating agent according to the above [1], wherein the compound (A) is the compound (A1).

[0020] [3] The coating agent according to [2] above, wherein the compound (A) is at least one benzoic acid selected from dihydroxybenzoic acid and trihydroxybenzoic acid.

[0021] [4] The coating agent according to [3] above, wherein the benzoic acid is at least one selected from 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, and 2,4,6-trihydroxybenzoic acid.

[0022] [5] The coating agent according to any one of [1] to [4], wherein the compound (A) is contained in an amount of 30 parts by mass or less relative to 100 parts by mass of the polyvinyl alcohol-based resin contained in the coating agent.

[0023] [6] The coating agent according to any one of [1] to [5] above, wherein the compound (A) is contained in an amount of 30 parts by mass or less per 100 parts by mass of the amine-modified polyvinyl alcohol.

[0024] [7] The coating agent according to any one of [1] to [6] above, wherein the amine-modified polyvinyl alcohol is a vinyl alcohol-vinyl amine copolymer containing a vinyl amine residue and a vinyl alcohol residue.

[0025] [8] The coating agent according to any one of [1] to [7] above, wherein the polyvinyl alcohol-based resin contained in the coating agent is composed of the amine-modified polyvinyl alcohol, or is composed of the amine-modified polyvinyl alcohol and a polyvinyl alcohol-based resin other than the amine-modified polyvinyl alcohol.

[0026] [9] The coating agent according to any one of [1] to [8] above, wherein the content of the polyvinyl alcohol-based resin is 50% by mass or more based on the total solid content.

[0027]

[10] The coating agent according to any one of [1] to [9] above, wherein the content of the amine-modified polyvinyl alcohol is 50% by mass or more based on the total solid content.

[0028]

[11] The coating agent according to any one of [1] to

[10] above, wherein the amount of amine modification of the polyvinyl alcohol-based resin contained in the coating agent is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the polyvinyl alcohol-based resin.

[0029]

[12] The coating agent according to any one of [1] to

[11] above, wherein in formula (1), R 1 ~R 6 One of them is a carboxyl group, R 1 ~R 6 Two or three of them are hydroxyl groups, and the rest are all hydrogen atoms.

[0030]

[13] The coating agent according to any one of [1] to

[12] above, wherein in formula (2), R 11 ~R 18 One of them is a carboxyl group, R 11 ~R 18 Two or three of them are hydroxyl groups, and the rest are all hydrogen atoms.

[0031]

[14] The coating agent according to any one of [1] to

[113] above, wherein the compound (A) is at least one selected from dihydroxybenzoic acid, trihydroxybenzoic acid, and dihydroxynaphthoic acid.

[0032]

[15] A coating film formed from the coating agent according to any one of [1] to

[14] above.

[0033]

[16] A laminate comprising a substrate and the coating film according to

[15] formed on at least one surface of the substrate.

[0034]

[17] The laminate according to

[16] above, further comprising a heat seal layer.

[0035]

[18] The laminate according to

[17] above, wherein the substrate, the coating film, and the heat seal layer are provided in this order.

[0036]

[19] The laminate according to any one of

[16] to

[18] above, wherein the peel strength when the substrate on which the coating film is formed is peeled from the heat seal layer provided on the coating film is 2 N / 15 mm or more.

[0037]

[20] The laminate according to any one of

[16] to

[19] above, wherein the oxygen permeability is 15.0 cc / m 2 ·day·MPa or less.

[0038]

[21] A laminated packaging material comprising the coating film according to

[15] above.

[0039]

[22] A laminated packaging material comprising the laminate according to any one of

[16] to

[20] above.

[0040] Effects of the Invention

[0041] According to the present invention, the water resistance of a coating film formed from a coating agent containing amine-modified polyvinyl alcohol is improved, and even when the coating film is used for various applications, it is possible to maintain good gas barrier properties without peeling. DETAILED DESCRIPTION

[0042] Hereinafter, the present invention will be described in detail with reference to embodiments.

[0043] <Coating agent>

[0044] The coating agent of the present invention contains an amine-modified polyvinyl alcohol and a compound (A).

[0045] [Amine-modified polyvinyl alcohol]

[0046] Amine-modified polyvinyl alcohol is a modified polyvinyl alcohol having an amino group. When the coating agent contains amine-modified polyvinyl alcohol, the gas barrier property of the coating film formed by the coating agent can be improved, and the adhesion to plastic films and the like can also be improved.

[0047] The amine-modified polyvinyl alcohol is typically a vinyl alcohol-vinyl amine copolymer containing a vinyl amine residue and a vinyl alcohol residue, and may be a block copolymer or a random copolymer thereof, or a combination thereof.

[0048] The method for producing the vinyl alcohol-vinyl amine copolymer is not particularly limited, and the copolymer can be obtained by copolymerizing N-vinyl amide and vinyl ester to obtain a copolymer composed of N-vinyl amide units and vinyl ester units, and hydrolyzing the obtained copolymer. The N-vinyl amide units and vinyl ester units are preferably hydrolyzed in a ratio of, for example, 70% or more, preferably 90% or more, and more preferably 95% or more.

[0049] Specific examples of N-vinylamide include N-vinylformamide and N-vinylacetamide, and among them, N-vinylformamide is preferred.

[0050] Specific examples of the vinyl ester include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl trimethylacetate, vinyl hexanoate, vinyl octanoate, vinyl neodecanoate, and the like. Among these, vinyl acetate is preferred.

[0051] In the vinyl alcohol-vinyl amine copolymer, the molar ratio of the vinyl amine residue and the vinyl alcohol residue (vinyl amine residue / vinyl alcohol residue) is not particularly limited, and is, for example, 1 / 99 or more and 50 / 50 or less, preferably 3 / 97 or more and 40 / 60 or less, and more preferably 5 / 95 or more and 25 / 75 or less. The vinyl alcohol-vinyl amine copolymer is easy to improve the adhesion to plastic films and the like by making the proportion of the vinyl amine residue high. In addition, by making the amount of the vinyl alcohol residue large, it is easy to show good gas barrier properties.

[0052] The vinyl alcohol-vinyl amine copolymer typically has the following structure.

[0053]

[0054] Here, based on all structural units, m is 0 mol% to 15 mol%, n is 50 mol% to 99 mol%, x is 0 mol% to 30 mol%, and y is 1 mol% to 50 mol%.

[0055] The viscosity of the aqueous solution of the amine-modified polyvinyl alcohol at 4 mass% concentration at 23°C is preferably 100 mPa·s or less, more preferably 50 mPa·s or less, and further preferably 20 mPa·s or less. In addition, it is preferably 2 m·sPa or more, preferably 3 mPa·s or more, and further preferably 4 mPa·s or more. The viscosity of the aqueous solution at 4 mass% concentration is measured by a B-type viscometer in accordance with JIS-Z-8803:2011 method.

[0056] In one embodiment, the amine-modified polyvinyl alcohol is preferably the main component in the coating agent. In this case, in the coating agent, the content of the amine-modified polyvinyl alcohol is based on the total solid content, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 75% by mass or more. By making the content of the amine-modified polyvinyl alcohol above the above lower limit, it is possible to impart appropriate gas barrier properties to the coating film formed by the coating agent. In addition, it is also easy to make the adhesion to plastic substrates etc. good. In addition, the so-called total solid content is the total amount of all components contained in the coating agent except the liquid medium.

[0057] In addition, the content of the amine-modified polyvinyl alcohol is preferably 94% by mass or less, more preferably 92% by mass or less, and further preferably 90% by mass or less based on the total solid content. By making the content of the amine-modified polyvinyl alcohol below the above upper limit, it is easy to make the coating agent contain the compound (A) described later in a desired amount.

[0058] In the coating agent of the present invention, as the polyvinyl alcohol-based resin, amine-modified polyvinyl alcohol may be used alone, or in addition to the amine-modified polyvinyl alcohol, a polyvinyl alcohol-based resin other than the amine-modified polyvinyl alcohol may be contained. The polyvinyl alcohol-based resin other than the amine-modified polyvinyl alcohol is preferably mixed with the amine-modified polyvinyl alcohol in a manner to obtain an amine-modified amount described later.

[0059] Therefore, regarding the coating agent involved in another preferred embodiment, it is better that the polyvinyl alcohol resin becomes the main component. In this case, in the coating agent, the content of the polyvinyl alcohol resin (that is, the total content of the amine-modified polyvinyl alcohol and the polyvinyl alcohol resin other than it) is based on the total solid content, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 75% by mass or more. By making the content of the polyvinyl alcohol resin above the above lower limit, it is easy to give appropriate gas barrier properties to the coating film, and it is also easy to make the adhesion to the plastic substrate etc. become good.

[0060] In addition, the content of the polyvinyl alcohol resin is preferably below 94% by mass, more preferably below 92% by mass, and further preferably below 90% by mass based on the total solid content. By making the content of the polyvinyl alcohol resin below the above upper limit, it is easy to make the coating agent contain the compound (A) described later in a desired amount.

[0061] The amine-modified amount of the polyvinyl alcohol-based resin contained in the coating agent is, for example, 1 mass part or more and 40 mass parts or less, preferably 2 mass parts or more and 30 mass parts or less, more preferably 3 mass parts or more and 20 mass parts or less, and further preferably 6 mass parts or more and 18 mass parts or less, relative to 100 mass parts of the polyvinyl alcohol-based resin. By adjusting the amine-modified amount to the above range, water resistance is improved, and it is easy to improve gas barrier properties and adhesion to plastic films, etc. In addition, the so-called amine-modified amount refers to the content of structural units (typically vinylamine residues) having an amine group relative to 100 mass parts of the polyvinyl alcohol-based resin.

[0062] [Compound (A)]

[0063] The compound (A) is at least one compound selected from the group consisting of a compound (A1) represented by the following formula (1) and a compound (A2) represented by the following formula (2).

[0064]

[0065] In formula (1), R 1 ~R 6 Each independently represents any one of a substituent such as a carboxyl group, a sulfo group (-SO3H), a hydroxyl group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom, and R 1 ~R 6 One of them is a carboxyl group or a sulfonyl group, R 1 ~R 6 2 or 3 of them are hydroxyl groups. 11 ~R 18 Each independently represents any substituent such as a carboxyl group, a sulfo group, a hydroxyl group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a halogen atom, and R 11 ~R 18 One of them is a carboxyl group or a sulfonyl group, R 11 ~R 18 Two or three of them are hydroxyl groups.

[0066] Compound (A) has a structure in which a plurality of hydroxyl groups and one carboxyl group or sulfonic group are bonded to an aromatic ring, thereby appropriately crosslinking the amine-modified polyvinyl alcohol. Therefore, since a crosslinking structure can be introduced into the coating film formed by the coating agent, water resistance is improved, and thus the coating film does not peel off even when used in an environment in contact with water, and good gas barrier properties can be maintained.

[0067] In addition, general cross-linking agents with high cross-linking effects sometimes produce ketone groups, etc., and yellowing and browning occur, but compound (A) is easy to suppress yellowing and browning during cross-linking, so it is easy to make the appearance of the coating formed by the coating agent good. Further, compound (A) has high safety, and can be used as a food additive according to the structure, and can be suitable for food applications. In addition, the coating agent containing amine-modified polyvinyl alcohol and compound (A) is less likely to gel, and the operability is also good.

[0068] R 1 ~R 6 and R 11 ~R 18 The alkyl group in the is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably an alkyl group having 1 or 2 carbon atoms.

[0069] The alkyl group may be a straight chain, a branched chain, or a cyclic structure. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and cyclohexyl. Among them, methyl and ethyl are more preferred, and methyl is further preferred.

[0070] R 1 ~R 6 and R 11 ~R 18 The aryl group in is preferably an aryl group having 6 to 9 carbon atoms. The aryl group may be a phenyl group or a naphthyl group, or may be an alkyl-substituted aryl group such as a tolyl group, a xylyl group, an ethylphenyl group, or a methylnaphthyl group.

[0071] R 1 ~R 6 and R 11 ~R 18 The halogen atom in ] includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0072] In formula (1), preferably R 1 ~R 6 One of them is a carboxyl group or a sulfonyl group, R 1 ~R 6 2 or 3 of them are hydroxyl groups, and the rest are all hydrogen atoms. Suitable specific examples of compound (A1) include dihydroxybenzenesulfonic acid, trihydroxybenzenesulfonic acid, dihydroxybenzoic acid, and trihydroxybenzoic acid. In formula (1), more preferably R1 ~R 6 Since one of them is a carboxyl group, dihydroxybenzoic acid or trihydroxybenzoic acid is more preferable.

[0073] In formula (2), R 11 ~R 18 One of them is a carboxyl group or a sulfonyl group, R 11 ~R 18 2 or 3 of them are hydroxyl groups, and the rest are all hydrogen atoms. Among them, R 11 ~R 18 Two of them are hydroxyl groups. 11 ~R 18 More preferably, one of them is a carboxyl group.

[0074] Examples of the compound (A2) represented by the formula (2) include dihydroxynaphthalenesulfonic acid and dihydroxynaphthoic acid, and among them, dihydroxynaphthoic acid is preferred.

[0075] Moreover, as a specific compound of compound (A2), 1, 4- dihydroxy-2-naphthoic acid, 3, 5- dihydroxy-2-naphthoic acid, 3, 7- dihydroxynaphthoic acid, etc. are mentioned.

[0076] Furthermore, from the viewpoint of improving crosslinking properties, the dihydroxynaphthoic acid is preferably a compound having two hydroxyl groups and one carboxylic acid group on the same ring, and a specific example of the compound is 1,4-dihydroxy-2-naphthoic acid.

[0077] Compound (A) is preferably compound (A1) shown in formula (1), wherein at least one benzoic acid selected from dihydroxybenzoic acid and trihydroxybenzoic acid is more preferably used. By using dihydroxybenzoic acid and trihydroxybenzoic acid, it is easy to make the water resistance of the film formed by the coating agent better. In addition, these benzoic acids are highly safe and can also be suitable for food applications. Further, there is a tendency that yellowing or browning of the coating film and gelation of the coating agent are not easy to occur.

[0078] Dihydroxybenzoic acid and trihydroxybenzoic acid vary in performance such as water resistance depending on the positions of the hydroxyl group and the carboxyl group. Preferred specific examples of compound (A) include 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,4,6-trihydroxybenzoic acid, and 3,4,5-trihydroxybenzoic acid from the viewpoint of water resistance.

[0079] Among the above, 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, and 2,4,6-trihydroxybenzoic acid are preferred. Among them, from the viewpoint of suppressing yellowing and browning and improving water resistance, 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, and 2,4,6-trihydroxybenzoic acid are more preferred, and 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, and 2,4,6-trihydroxybenzoic acid are particularly preferred.

[0080] Furthermore, from the viewpoint of further suppressing yellowing and browning, dihydroxybenzoic acid is preferred.

[0081] The compound (A) may be used alone or in combination of two.

[0082] In the coating agent involved in one embodiment, the compounding amount of compound (A) is preferably 30 parts by mass or less relative to 100 parts by mass of amine-modified polyvinyl alcohol. By making the compounding amount of compound (A) less than 30 parts by mass, gelation, yellowing and browning are not easily occurred, and water resistance can be made good at the same time. From these viewpoints, the compounding amount of compound (A) is more preferably 28 parts by mass or less relative to 100 parts by mass of amine-modified polyvinyl alcohol, more preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.

[0083] In addition, the compounding amount of the compound (A) is preferably 6 parts by mass or more relative to 100 parts by mass of the amine-modified polyvinyl alcohol. By being 6 parts by mass or more, it is easy to make the water resistance good. The compounding amount of the compound (A) is more preferably 8 parts by mass or more, and further preferably 10 parts by mass or more relative to 100 parts by mass of the amine-modified polyvinyl alcohol.

[0084] As described above, in another embodiment, the coating agent, in addition to amine-modified polyvinyl alcohol, also includes a polyvinyl alcohol-based resin other than amine-modified polyvinyl alcohol as a polyvinyl alcohol-based resin. Therefore, in another preferred coating agent, it is not easy to gel, yellow and brown, and the water resistance is good. Considering that the compounding amount of compound (A) is 30 mass parts or less relative to 100 mass parts of polyvinyl alcohol-based resin contained in the coating agent, it is good, more preferably 28 mass parts or less, more preferably 25 mass parts or less, and more preferably 20 mass parts or less. In addition, from the viewpoint of being easy to make water resistance good, the compounding amount of compound (A) is preferably 6 mass parts or more relative to 100 mass parts of polyvinyl alcohol-based resin, more preferably 8 mass parts or more, and more preferably 10 mass parts or more.

[0085] [Other ingredients]

[0086] The coating agent of the present invention may contain additives other than the compound (A), for example, an inorganic layered compound. The inorganic layered compound is an inorganic compound in which extremely thin unit crystal layers are stacked to form a single layered particle.

[0087] Representative substances of the inorganic layered compounds include hydrated silicates such as phyllosilicate minerals, for example, kaolinite group clay minerals such as halloysite, kaolinite, hydrohaloysite, dickite, and nacrite, antigorite group clay minerals such as antigorite and chrysotile, smectite group clay minerals such as montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and spheneite, vermiculite group clay minerals such as vermiculite, muscovite, phlogopite, nacral mica, tetrasilicon mica, taenia mica, and other mica or mica group clay minerals, and the like.

[0088] These inorganic layer compounds may be used alone or in combination of two or more. Among these inorganic layer compounds, smectite clay minerals such as montmorillonite and mica clay minerals such as water-swellable mica are preferred.

[0089] The content of the inorganic layered compound in the coating agent is, for example, 5 mass % to 35 mass %, and preferably 8 mass % to 30 mass %, based on the total solid content.

[0090] As long as the effect of the present invention is not impaired, the coating agent may contain substances other than the inorganic layered compound as additives other than compound (A). Such additives include, for example, antioxidants, weathering agents, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet light absorbers, plasticizers, antistatic agents, colorants, fillers other than the inorganic layered compound, defoamers, silane coupling agents, surfactants and other additives.

[0091] In addition, the resin component constituting the coating agent may be a single amine-modified polyvinyl alcohol, but may contain resin components other than amine-modified polyvinyl alcohol, for example, a hydroxyl-containing resin other than amine-modified polyvinyl alcohol, as long as the effect of the present invention is not impaired. Specifically, polyvinyl alcohol-based resins other than amine-modified polyvinyl alcohol may be mentioned.

[0092] The polyvinyl alcohol-based resin other than the amine-modified polyvinyl alcohol is not particularly limited, and may be unmodified polyvinyl alcohol. Unmodified polyvinyl alcohol is obtained by saponifying polyvinyl ester, and preferably consists of a vinyl alcohol residue, or a vinyl alcohol residue and a vinyl ester residue.

[0093] [Liquid medium]

[0094] The coating agent of the present invention contains a liquid medium such as water or an organic solvent, and is preferably diluted by the liquid medium. The components constituting the coating agent are preferably dissolved or dispersed in the liquid medium.

[0095] As the organic solvent used as the liquid medium, for example, monohydric alcohol, diol, dimethylformamide, dimethyl sulfoxide, acetone, etc. can be mentioned. As the monohydric alcohol, for example, methanol, ethanol, propanol, isopropanol, butanol, etc. can be mentioned. As the organic solvent, ethanol and isopropanol are preferred. By using ethanol and isopropanol, the drying of the amine-modified polyvinyl alcohol and compound (A) becomes faster, and in addition, it is highly safe and can be suitable for food applications.

[0096] The coating agent is preferably an aqueous coating agent using water as a liquid medium. If water is used as a liquid medium, it is easy to dissolve the amine-modified polyvinyl alcohol and the like in the liquid medium, and it is highly safe and can also be suitably used for food applications.

[0097] In the water-based coating agent, water can be used alone as the liquid medium, but from the viewpoints of the drying time of the coating agent, the stability of the coating agent, the solubility of each component in the coating agent, etc., water and an organic solvent can be used together to form a mixed medium. At this time, the organic solvent used in combination is not particularly limited, but is preferably a monohydric alcohol, and ethanol is more preferably used. The mass ratio of water to the organic solvent in the mixed medium (water / organic solvent) is not particularly limited, for example, it is 30 / 70 or more and 95 / 5 or less, preferably 50 / 50 or more and 90 / 10 or less.

[0098] In addition, from the viewpoints of film-forming properties, workability, solubility of each component, etc., the solid content concentration in the coating agent is, for example, 0.5 mass % to 20 mass %, preferably 1 mass % to 12 mass %, and more preferably 2 mass % to 8 mass %.

[0099] The coating agent of the present invention can be produced by a general coating agent production method, for example, by adding amine-modified polyvinyl alcohol, compound (A), and other components as required to a liquid medium and mixing them.

[0100] <Coating>

[0101] The coating of the present invention is formed by the above-mentioned coating agent. The coating of the present invention can be formed, for example, by applying the coating agent to a substrate and drying appropriately as needed. In the coating, the amine-modified polyvinyl alcohol contained in the coating agent reacts with the compound (A) to be cross-linked. The compound (A) and the amine-modified polyvinyl alcohol may have reacted in the coating agent before being applied to the substrate, or may react after the coating. The coating of the present invention has a low oxygen transmittance and can be suitable for use as a gas barrier layer.

[0102] The coating method of the coating agent to the substrate is not particularly limited, and known methods can be used. As the coating method, for example, a gravure coating method, a roll coating method, a doctor blade method, a die coating method, a rod coating method, a dipping method, a spray coating method, a curtain coating method, a spin coating method, a flexographic coating method, a screen coating method, a coating method using a brush, etc. can be mentioned.

[0103] Furthermore, in order to improve the adhesion between the substrate and the coating film, the surface of the substrate coated with the coating agent may be subjected to surface treatment such as corona treatment, ozone treatment, electron beam treatment, or coating of a bonding coating agent.

[0104] There is no particular limitation on the drying of the applied coating agent, and known means can be used. Drying is preferably performed in a manner that the liquid medium contained in the coating agent evaporates. Examples of drying include drying by heating, drying by non-heating means such as decompression, and drying by a combination thereof. The drying temperature by heating is, for example, 30 to 150° C., preferably 40 to 100° C., and the drying time is, for example, 1 second to 24 hours, more preferably 10 seconds to 60 minutes.

[0105] The coating amount of the coating film formed by the coating agent is, for example, 0.5 to 5.0 g / m 3 , preferably 1.0 to 2.0 g / m 3 When the coating amount is within the above range, the gas barrier properties and the like can be improved without excessively increasing the thickness of the coating film.

[0106] The substrate is not particularly limited, but is preferably a resin film. Specifically, the resin used in the resin film includes, for example, polyethylene resins such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene resins such as homopolypropylene and random polypropylene, ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, ethylene-octene copolymers, poly-4-methylpentene-1, cyclic olefin resins, ethylene-vinyl acetate copolymers, ethylene-methyl (meth)acrylate copolymers, ethylene-(meth)acrylic acid ester copolymers, Olefin resins such as olefin copolymers and ionomer resins, ester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate, amide resins such as polyamide 6, polyamide 66, meta-xylylenediamine-adipic acid condensate, and polymethyl methacrylimide, acrylic resins, styrene resins, polyacrylonitrile resins, cellulose resins such as cellophane, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinylidene fluoride resins, polycarbonate resins, and the like.

[0107] In the resin film, the above resin can be used alone or in combination of two or more resins. In addition, the resin film can be a multilayer film, for example, a multilayer film in which each layer is formed by different types of resins. In addition, as the resin film, it can be non-stretched or stretched film. As the stretched film, stretched propylene resin film (OPP film), stretched PET film, stretched amide resin film, etc. can be cited as preferred specific examples.

[0108] As the resin film, among the above, an olefin resin film, an ester resin film, and an amide resin film are preferable.

[0109] The thickness of the substrate is not particularly limited, but is, for example, 1 to 500 μm, preferably 5 to 200 μm.

[0110] In addition, the substrate can be used as a heat seal layer bonded to other members by heat fusion by appropriately selecting the type of thermoplastic resin used as the thermoplastic resin layer. In such a case, the resin constituting the substrate is preferably an olefin resin.

[0111] <Laminate>

[0112] The present invention also provides a laminate having a substrate and the above-mentioned coating formed on at least one side of the substrate. The coating is formed by a coating agent as described above. The coating can be laminated on the surface of the substrate via other layers such as a bonding coating layer and a printing layer, or it can be directly formed on the surface of the substrate. In the laminate, the coating can be arranged only on one side of the substrate, or it can be arranged on both sides of the substrate. In addition, a resin film and a printing layer can be further laminated on the above-mentioned laminate.

[0113] Such a laminate having a substrate and a coating film can be used as a gas barrier film because the coating film has excellent gas barrier properties.

[0114] In addition, the laminate preferably has a heat seal layer as a layer different from the above-mentioned substrate. The heat seal layer is a layer that can be bonded to other layers by heat fusion, and is preferably a thermoplastic resin layer. The thermoplastic resin used as the heat seal layer is preferably an olefin resin. As the olefin resin, the substances listed as resins that can be used in the above-mentioned substrate can be used, but polyethylene resins such as LDPE and LLDPE are more preferred. The thickness of the heat seal layer as a layer different from the substrate is not particularly limited, and is, for example, 10 to 500 μm, preferably 20 to 200 μm. By making the thickness of the heat seal layer within the above-mentioned range, it is possible to impart appropriate heat sealability to the heat seal layer without making the thickness of the laminate excessively large.

[0115] The heat seal layer may be provided on the side of the substrate opposite to the surface on which the coating film is formed, but is preferably provided on the surface of the substrate on which the coating film is formed. That is, the laminate preferably has a layer structure in which the substrate, the coating film, and the heat seal layer are provided in sequence. By having such a layer structure, the laminate can protect the coating film from both sides by the substrate and the heat seal layer, and can be bonded to other films or the like by heating via the heat seal layer.

[0116] An adhesive layer may be provided between the heat seal layer and the coating film, and the heat seal layer is preferably bonded to the surface of the substrate on which the coating film is formed via the adhesive layer. The adhesive layer is preferably formed of a known adhesive such as an adhesive for dry lamination. From the viewpoint of improving adhesion, the surface of the heat seal layer on the side to be bonded to the substrate may be subjected to surface treatment such as corona treatment, ozone treatment, electron beam treatment, or application of a bonding coating agent.

[0117] From the viewpoint of achieving good gas barrier properties, the above-mentioned laminate preferably has an oxygen permeability of 15 cc / m 2 ·day·MPa or less, more preferably 12cc / m 2 ·day·MPa or less, more preferably 10cc / m 2 ·day·MPa or less. The lower the oxygen permeability, the better, but as long as it is 0cc / m 2 ·day·MPa or above.

[0118] The oxygen permeability is a value measured in an atmosphere of 23° C. and 0% RH in accordance with JIS-K-7126-2 (isobaric method).

[0119] When the laminate has a heat seal layer and the heat seal layer is arranged on the side of the substrate on which the coating film is formed, the adhesion of the coating film to the substrate, the adhesive layer, etc. becomes higher, and the lamination strength also becomes higher. The lamination strength in such a case is specifically preferably more than 2N / 15mm, more preferably more than 4N / 15mm. The higher the lamination strength, the better, and its upper limit is not particularly limited, for example, less than 30N / 15mm. In addition, the lamination strength is the peel strength when the substrate on which the coating film is formed is peeled off from the heat seal layer arranged on the coating film. The determination of the peel strength is carried out under the conditions described in the embodiments as well.

[0120] <Laminated packaging materials>

[0121] In the present invention, the laminated packaging material is a packaging material having the above-mentioned coating film. The laminated packaging material is preferably constituted by a laminate having the coating film and the substrate as described in detail above.

[0122] The laminated packaging material is preferably a packaging material used by being laminated on components such as films. From such a viewpoint, the laminated packaging material preferably has a heat-sealing layer. Therefore, the laminated packaging material is preferably a laminate having a base material, a coating film, and a heat-sealing layer. In addition, a printed layer may be provided on the coating film.

[0123] The laminated packaging material can be used for packaging of various articles, but is preferably used for food. As described above, the laminated packaging material (laminated body) of the present invention has low oxygen transmittance and good gas barrier properties, so it can be used for food applications to maintain the freshness of the packaged food for a long time. In addition, the coating film has good water resistance as described above, so the laminated packaging material can also be suitably used for applications where water is easy to adhere, for boiling sterilization, and for packaging of foods containing a large amount of water.

[0124] The laminated packaging material is not particularly limited, and can be used in a bag or pouch shape, for example. In addition, the laminated packaging material can be prepared in two sheets, or one sheet can be folded back so that the heat sealing layers overlap each other, and the heat sealing layers are heated and fused together for use, or it can be overlapped with other components and heated and fused together for use. The laminated packaging material is preferably made into a pouch or bag shape by heating and fusing the heat sealing layers together, or by heating and fusing the heat sealing layers with other components.

[0125] Example

[0126] The present invention will be described in further detail by way of examples, but the present invention is not limited to these examples at all.

[0127] [Example 1]

[0128] To 100 parts by mass of a vinyl alcohol-vinylamine copolymer (manufactured by Seiki Spacer Chemicals Co., Ltd., trade name "Ultiloc (registered trademark) 5003", amine modification amount 12 parts by mass) as a polyvinyl alcohol-based resin, 25 parts by mass of 2,3-dihydroxybenzoic acid (primary reagent) as a compound (A) was added, and the mixture was diluted with a mixed solvent of water and ethanol (water / ethanol (mass ratio) = 2 / 1) to adjust to a 5% by mass solution, thereby obtaining a coating agent.

[0129] The coating agent obtained was passed through a liquid state to a coating amount of 20 g / m 2 The wire rod was set in the right and left directions, and the corona-treated surface of a biaxially stretched polyamide film ("Hadeen N1102" manufactured by Toyobo Co., Ltd.) having one surface subjected to corona treatment was coated with a coating amount of 1.0 g / m after drying. 2 The mixture was applied in a manner of 1000 μm and dried in an oven at 80° C. for 2 minutes to form a coating film.

[0130] Then, a dry lamination adhesive (product name: Mitsui Chemicals, Inc., main agent: Takluck A-616 curing agent: Takluck A65) was applied to the coating film forming surface of the substrate. The substrate with the adhesive applied to the coating film forming surface was attached to the corona-treated surface of an LLDPE film (thickness: 70 μm, Toyobo Co., Ltd. "Ricks L4102") with one side corona-treated via the adhesive to obtain a laminated packaging material. The obtained laminated packaging material was placed in an environment of 40°C for 72 hours for curing. Then, the produced laminated film was cut into a certain size, the LLDPE surfaces that could be heat-fused were overlapped, one side was used as the opening, and the remaining three sides were heat-sealed to produce a test bag.

[0131] [Examples 2 to 12, 16, Comparative Examples 1 to 3]

[0132] The same procedures as in Example 1 were carried out except that the type and addition amount of the compound (A) were changed as shown in Tables 1 to 4. In addition, a primary reagent was used as the compound (A) in each of the Examples and Comparative Examples.

[0133] [Examples 13 to 15, 17]

[0134] As the polyvinyl alcohol-based resin, instead of a single vinyl alcohol-vinylamine copolymer, a product obtained by mixing a polyvinyl alcohol-based resin (manufactured by Seiki Spacer Chemicals Co., Ltd., trade name "SELVOL103") with a vinyl alcohol-vinylamine copolymer ("Ultiloc (registered trademark) 5003") in such a manner as to achieve the amine modification amount described in Tables 3 and 4 was used, and the same procedures as in Example 1 were performed except that the type and addition amount of compound (A) were changed as described in Tables 3 and 4.

[0135] Each of the Examples and Comparative Examples was evaluated as described below.

[0136] [Oxygen permeability]

[0137] The laminated packaging materials obtained in each example and comparative example were measured for oxygen transmission rate (cc / (m2)) in an atmosphere of 23°C and 0% RH using an oxygen transmission rate measuring apparatus (trade name "OXTRAN", manufactured by MOCON) in accordance with JIS-K-7126-2 (isobaric method). 2 ·day·MPa)).

[0138] [Lamination strength]

[0139] The laminated packaging materials obtained in each example and comparative example were measured for lamination strength by a method in accordance with JIS-K-7127. Specifically, the laminated packaging materials were cut into strips with a width of 15 mm, and the polyamide film (substrate) on which the coating was formed was peeled off from the LLDPE film (heat-sealing layer) in a T-shape at a speed of 200 mm / min using a tensile tester "Tensilon" at room temperature (23°C), and the lamination strength (N / 15 mm) was measured.

[0140] [Water resistance evaluation]

[0141] The laminated packaging materials obtained in each example and comparative example were sandwiched between two paper wipers (trade name "Keyword", manufactured by Nippon Paper Manufacturing Co., Ltd.) fully impregnated with water, and then sandwiched between transparent A4-sized folders, and left at room temperature (20° C.). The wrinkle state and peeling state of the laminated packaging materials after 1 hour and 8 hours were observed and evaluated according to the following evaluation criteria.

[0142] A: No wrinkles or peeling occurs.

[0143] AB: Although wrinkles and peeling occurred slightly, it was judged to be at a level that would not cause any practical problems.

[0144] B: At least one of wrinkles and peeling occurs more frequently.

[0145] C: Large wrinkles were introduced, or the LLDPE film and the polyamide film were completely separated, which was a level that was completely unusable in practical use.

[0146] [Yellowing property]

[0147] The test bags obtained in each example and comparative example were compared with a blank group, and the yellowing property was evaluated by visual observation. Then, the bags were left at room temperature for 4 weeks, and the appearance after the leftovers was also observed. If there were changes, the evaluation after the leftovers was also shown in Tables 1 to 3. In addition, a test bag prepared in the same manner as in Example 1 except that the compound (A) was not mixed was used as a blank group.

[0148] A: The appearance is the same as that of the blank group.

[0149] B: Yellowing occurred slightly more than in the blank group, but it was at a level that did not cause problems in appearance.

[0150] C: Compared with the blank group, yellowing or browning occurred significantly more, and it was at a level that could not be used in terms of appearance and practicality.

[0151] [Table 1]

[0152]

[0153] [Table 2]

[0154]

[0155] [Table 3]

[0156]

[0157] [Table 4]

[0158]

[0159] * In Comparative Examples 1 to 3, water resistance evaluation after 8 hours was not performed.

[0160] ※The addition amount in Tables 1 to 4 is parts by mass of the compound (A) relative to 100 parts by mass of the polyvinyl alcohol-based resin.

[0161] As shown in Tables 1 to 4 above, in each example, by mixing a compound (A) having one carboxyl group and two or three hydroxyl groups bonded to an aromatic ring, the amine-modified polyvinyl alcohol is appropriately cross-linked, and the water resistance of the coating film becomes good. In addition, the lamination strength is high, the adhesion to the substrate is good, and the oxygen permeability is low, and the gas barrier property is also good.

[0162] On the other hand, in each of the comparative examples, since the compound (A) having the above-mentioned specific structure was not blended, the amine-modified polyvinyl alcohol was not appropriately cross-linked, and the water resistance did not become good.

Claims

1. A coating agent comprising: Amine-modified polyvinyl alcohol; and At least one compound (A) selected from the group consisting of a compound (A1) represented by the following formula (1) and a compound (A2) represented by the following formula (2), in, In formula (1), R 1 ~R 6 are each independently a carboxyl group, a sulfo group, a hydroxyl group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom, and R 1 ~R 6 One of them is either a carboxyl group or a sulfone group, and R 1 ~R 6 2 or 3 of them are hydroxyl groups; in formula (2), R 11 ~R 18 are each independently a carboxyl group, a sulfo group, a hydroxyl group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom, and R 11 ~R 18 One of them is either a carboxyl group or a sulfone group, and R 11 ~R 18 Two or three of them are hydroxyl groups. 2 . The coating agent according to claim 1 , wherein the compound (A) is the compound (A1). 3 . The coating agent according to claim 2 , wherein the compound (A) is at least one benzoic acid selected from dihydroxybenzoic acid and trihydroxybenzoic acid. 4 . The coating agent according to claim 3 , wherein the benzoic acid is at least one selected from the group consisting of 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, and 2,4,6-trihydroxybenzoic acid. 5 . The coating agent according to claim 1 , wherein the compound (A) is contained in an amount of 30 parts by mass or less relative to 100 parts by mass of the polyvinyl alcohol-based resin contained in the coating agent. 6 . A coating film formed from the coating agent according to claim 1 .

7. A laminated packaging material comprising the coating film according to claim 6.

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