JP7622985B2 - Coatings and laminates - Google Patents

Description

The present invention relates to a coating agent that has excellent coatability and film-forming properties and forms a resin layer that has excellent heat sealability, waterproofness, and oil resistance.

Conventionally, aqueous adhesives for paper containing polyolefin resins have been known. For example, the aqueous adhesive for paper disclosed in Patent Document 1 is suitable as an adhesive between paper and various thermoplastic resin films.

JP 2003-213233 A

In light of the recent marine plastic problem, the use of paper, instead of thermoplastic resin films, has been promoted as a material for packaging materials, disposable food containers, etc. When using paper as such a material, the aqueous coating agent applied to the paper is required to have excellent coatability and film-forming properties.
However, the aqueous paper adhesive disclosed in Patent Document 1 sometimes has insufficient coatability and film-forming properties, and the resin layer formed from this adhesive sometimes has insufficient heat sealability, waterproofness, and oil resistance.
In view of the problems of the conventional techniques as described above, an object of the present invention is to provide a coating agent which has excellent coatability and film-forming properties for substrates such as paper or nonwoven fabric into which the coating agent is easily absorbed, and which forms a resin layer which has excellent heat sealability, waterproofness, and oil resistance.

Means for Solving the Problems The present inventors conducted intensive research to solve the above problems, and as a result, discovered that a coating agent comprising an aqueous coating agent containing an acid-modified polyolefin resin and one or more types selected from a urethane resin, an acrylic resin, and a hydroxyl group-containing compound solves the above problems, thereby arriving at the present invention.
That is, the gist of the present invention is as follows.

(1) an acid-modified polyolefin resin;
a urethane resin and/or an acrylic resin ;
A hydroxyl group-containing compound (excluding fibrous cellulose) ,
A coating agent comprising: an aqueous medium.
(2) The coating agent according to (1), characterized in that the content of the urethane resin and/or acrylic resin is more than 10 parts by mass and not more than 100 parts by mass per 100 parts by mass of the acid-modified polyolefin resin.
(3) A laminate comprising a paper base material and a resin layer,
The resin layer comprises an acid-modified polyolefin resin,
a urethane resin and/or an acrylic resin ;
A laminate comprising: a hydroxyl group-containing compound (excluding fibrous cellulose) ;
(4) A packaging material comprising the laminate described in (3) above.
(5) A paper container comprising the laminate described in (3) above.

The coating agent of the present invention is a compound of an acid-modified polyolefin resin and one or more selected from urethane resin, acrylic resin, and hydroxyl group-containing compound, and therefore has excellent coatability and film-forming properties for substrates such as paper or nonwoven fabric that are easily permeated by the coating agent, and the formed resin layer also has excellent heat sealability, waterproofness, and oil resistance.

The present invention will be described in detail below.
The coating agent of the present invention contains an acid-modified polyolefin resin, one or more resins selected from a urethane resin, an acrylic resin, and a hydroxyl group-containing compound, and an aqueous medium.

<Acid-modified polyolefin resin>
The acid-modified polyolefin resin constituting the coating agent of the present invention is preferably a copolymer containing an acid-modified component and an olefin component as copolymerization components. By modifying the polyolefin resin with an acid, the coating agent of the present invention has improved film-forming properties and coatability onto a substrate.

The acid-modified component is preferably an unsaturated carboxylic acid component, and is introduced by an unsaturated carboxylic acid or its anhydride. Specific examples of the unsaturated carboxylic acid component include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, etc., as well as half esters and half amides of unsaturated dicarboxylic acids. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred, with acrylic acid and maleic anhydride being particularly preferred.

The content of the acid-modified component in the acid-modified polyolefin resin is not particularly limited, but is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, and even more preferably 2 to 20% by mass. If the content of the acid-modified component is less than 1% by mass, the acid-modified polyolefin resin may not be able to be stably dispersed in an aqueous medium, and if it exceeds 40% by mass, the resin layer formed may have poor waterproofing.

Examples of the olefin components constituting the acid-modified polyolefin resin include alkenes having 2 to 6 carbon atoms, such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene, and mixtures of these can also be used. Among these, alkenes having 2 to 4 carbon atoms, such as ethylene, propylene, isobutylene, and 1-butene, are preferred, with ethylene being more preferred.

From the viewpoint of improving waterproofness and oil resistance, the content of the olefin component in the acid-modified polyolefin resin is preferably 50% by mass or more, and more preferably 70% by mass or more.

The acid-modified polyolefin resin preferably contains a (meth)acrylic acid ester component to improve adhesion to the substrate. The content of the (meth)acrylic acid ester component in the acid-modified polyolefin resin is preferably 0.5 to 40% by mass, more preferably 1 to 35% by mass, even more preferably 3 to 30% by mass, particularly preferably 5 to 25% by mass, and most preferably 10 to 25% by mass.

The (meth)acrylic acid ester component includes esters of (meth)acrylic acid and alcohols having 1 to 30 carbon atoms, and among these, from the viewpoint of ease of availability, esters of (meth)acrylic acid and alcohols having 1 to 20 carbon atoms are preferred. Specific examples of such compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate. Mixtures of these may also be used. Among these, from the viewpoint of improving adhesion to the substrate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl acrylate, and octyl acrylate are more preferred, ethyl acrylate and butyl acrylate are more preferred, and ethyl acrylate is particularly preferred. Note that "(meth)acrylic acid or more" means "acrylic acid or methacrylic acid or more".

In addition to the above components, the acid-modified polyolefin resin may contain other components in an amount of about 10% by mass or less of the acid-modified polyolefin resin. Examples of other components include alkenes and dienes having more than 6 carbon atoms, such as 1-octene and norbornenes, maleic acid esters, such as dimethyl maleate, diethyl maleate, and dibutyl maleate, (meth)acrylic acid amides, alkyl vinyl ethers, such as methyl vinyl ether and ethyl vinyl ether, vinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and vinyl versatate, as well as vinyl alcohol obtained by saponifying vinyl esters with a basic compound, 2-hydroxyethyl acrylate, glycidyl (meth)acrylate, (meth)acrylonitrile, styrene, substituted styrene, carbon monoxide, and sulfur dioxide, and mixtures of these may also be used.

The acid-modified component constituting the acid-modified polyolefin resin may also contain an N-substituted amide structure in which the hydroxyl group of the carboxyl group is replaced with an N,N-dimethylamino group, an N,N-diethylamino group, or the like.

Examples of acid-modified polyolefin resins include ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid-maleic anhydride copolymers, acid-modified polyethylene, acid-modified polypropylene, acid-modified ethylene-propylene resins, acid-modified ethylene-butene resins, acid-modified propylene-butene resins, acid-modified ethylene-propylene-butene resins, and ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid copolymers in which these acid-modified resins are further acrylic-modified with (meth)acrylic acid esters or the like. Among these, ethylene-(meth)acrylic acid-maleic anhydride copolymers are preferred. Furthermore, the acid-modified polyolefin resins may be chlorinated in the range of 5 to 40% by mass.

As acid-modified polyolefin resins, commercially available products such as the Bondine series manufactured by Arkema, the Bestplast series manufactured by Evonik Japan, the Primacol series manufactured by Dow Chemical, the Umex series manufactured by Sanyo Chemical, the Admar series manufactured by Mitsui Chemicals, and the Toyotack series manufactured by Toyobo can be used. Commercially available water-based products can also be used, such as the Superclone series manufactured by Nippon Paper Chemicals, the Zaixen series manufactured by Sumitomo Seika Chemicals, the Chemipearl series manufactured by Mitsui Chemicals, and the Hardlen series manufactured by Toyobo.

<Urethane resin, acrylic resin, hydroxyl group-containing compound>
The coating agent of the present invention must contain at least one type selected from the group consisting of urethane resins, acrylic resins and hydroxyl group-containing compounds.
The coating agent of the present invention contains one or more selected from urethane resins, acrylic resins, and hydroxyl group-containing compounds, thereby improving the surface coatability and film-forming properties of substrates such as paper and nonwoven fabrics into which the coating agent is easily absorbed. In addition, the resin layer formed from the coating film can be ensured to have a sufficient thickness, and furthermore, the coating agent has excellent heat sealability, waterproofness, and oil resistance.
Furthermore, the coating agent of the present invention can adjust its viscosity by containing a hydroxyl group-containing compound, which makes it difficult for the coating agent to penetrate into the substrate, thereby ensuring a sufficient thickness of the coating film.

The coating agent of the present invention contains a urethane resin and/or an acrylic resin as a resin component other than the acid-modified polyolefin resin, and thus can form a resin layer that is superior in waterproofness and oil resistance compared to when other resins such as polyester resins are contained. The glass transition temperature of the urethane resin and the acrylic resin is preferably 0°C or higher, more preferably 10°C or higher, and even more preferably 30°C or higher.

When the coating agent contains a urethane resin and/or an acrylic resin, the content is preferably more than 10 parts by mass, more preferably more than 10 parts by mass and not more than 100 parts by mass, even more preferably 12 to 70 parts by mass, and even more preferably 13 to 60 parts by mass, relative to 100 parts by mass of the acid-modified polyolefin resin. If the content of the urethane resin and/or the acrylic resin is 10 parts by mass or less, the coating agent may have poor film formation and the formed resin layer may have poor heat sealability, and if the content exceeds 100 parts by mass, the coating agent may have poor coatability.

Examples of hydroxyl group-containing compounds include celluloses such as carrageenan, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose; polysaccharides such as xanthan gum, guar gum, pectin, and modified starch; and polyvinyl alcohol. Among these, carboxymethyl cellulose and polysaccharides are preferred because the viscosity of the coating agent can be easily controlled, and polysaccharides are more preferred because they form a resin layer with excellent oil resistance.

When the coating agent contains a hydroxyl group-containing compound, the content is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the acid-modified polyolefin resin. If the content of the hydroxyl group-containing compound is less than 0.2 parts by mass, the viscosity of the coating agent cannot be adequately controlled, and the resin layer formed may have poor heat sealability, and if the content exceeds 5 parts by mass, the stability of the coating agent may decrease.

The coating agent of the present invention preferably contains a urethane resin and/or an acrylic resin in combination with a hydroxyl group-containing compound in order to further improve the waterproofness and oil resistance of the resin layer formed.

<Aqueous medium>
The aqueous medium constituting the paper coating agent of the present invention is water or a liquid mainly composed of water, and may contain a basic compound and a hydrophilic organic solvent. When the aqueous medium contains a hydrophilic organic solvent, the coating agent exhibits the effect of improving the wettability to the substrate, and improving the coatability and film-forming property.

The content of the hydrophilic organic solvent is preferably 1 to 50% by mass, more preferably 3 to 30% by mass, and even more preferably 5 to 25% by mass, based on the total amount of the aqueous medium in order to provide the substrate with adequate wettability.

Examples of hydrophilic organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, and cyclohexanone; ethers such as tetrahydrofuran and dioxane; ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, and 3-methoxybutyl acetate. Examples of suitable glycerols include esters such as ethyl ether, methyl propionate, ethyl propionate, diethyl carbonate, and dimethyl carbonate; glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and ethylene glycol ethyl ether acetate; and further, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methoxy-3-methyl-1-butanol, methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate, 1,2-dimethylglycerin, 1,3-dimethylglycerin, and trimethylglycerin.

Examples of basic compounds include ammonia, triethylamine, N,N-dimethylethanolamine, isopropylamine, aminoethanol, dimethylaminoethanol, diethylaminoethanol, ethylamine, diethylamine, isobutylamine, dipropylamine, 3-ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, pyrrole, and pyridine.

<Additives>
The coating agent of the present invention may contain additives such as other polymers and crosslinking agents in order to further improve the performance depending on the purpose.
The other polymers are not particularly limited, and examples thereof include polyvinyl acetate, ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, styrene-maleic acid resins, styrene-butadiene resins, butadiene resins, acrylonitrile-butadiene resins, poly(meth)acrylonitrile resins, (meth)acrylamide resins, chlorinated polyethylene resins, chlorinated polypropylene resins, tackifier resins such as modified nylon resins and rosin, phenolic resins, silicone resins, and epoxy resins, and a plurality of these may be used in combination as necessary.

The crosslinking agent is not particularly limited, and examples thereof include a crosslinking agent having self-crosslinking properties, a compound having multiple functional groups in the molecule that react with a carboxyl group, and a metal having a polyvalent coordination site. Specifically, isocyanate compounds, melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, oxazoline group-containing compounds, zirconium salt compounds, silane coupling agents, and the like are preferred. Furthermore, multiple of these crosslinking agents may be used simultaneously.

The content of the crosslinking agent is preferably 0.01 to 80 parts by mass, more preferably 0.1 to 50 parts by mass, and even more preferably 0.5 to 30 parts by mass, per 100 parts by mass of the acid-modified polyolefin resin. If the content of the crosslinking agent is less than 0.01 parts by mass, the performance of the resin layer formed tends not to improve, and if it exceeds 80 parts by mass, performance such as processability may decrease.

The coating agent of the present invention may further contain various chemicals such as leveling agents, defoamers, anti-popping agents, pigment dispersants, UV absorbers, weather resistance agents, and flame retardants, as necessary.

<Coating agent>
The coating agent of the present invention contains the above-mentioned acid-modified polyolefin resin, one or more compounds selected from a urethane resin, an acrylic resin, and a hydroxyl group-containing compound, and an aqueous medium, and it is preferable that the acid-modified polyolefin resin is dispersed in the aqueous medium.
The content of the resin component in the coating agent of the present invention can be appropriately selected depending on the coating conditions, the desired thickness and performance of the coating film, etc., and is not particularly limited. From the viewpoint of maintaining an appropriate viscosity and exhibiting good film-forming properties, the content is preferably 1 to 60 mass%, more preferably 3 to 55 mass%, even more preferably 5 to 50 mass%, and particularly preferably 10 to 45 mass%.
In order to suppress penetration into the substrate, the viscosity of the coating agent of the present invention is preferably 5 to 3000 mPa·s, more preferably 10 to 2000 mPa·s, and even more preferably 50 to 1500 Pa·s. If the viscosity of the coating agent is less than 5 mPa·s, it may be difficult to apply the coating agent, and if the viscosity exceeds 3000 mPa·s, it may also be difficult to apply the coating agent.

The coating agent of the present invention has excellent coatability and film-forming properties for substrates that are easily permeated, such as paper or nonwoven fabric, and can be uniformly applied to the substrate surface by a known coating method, such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, brush coating, etc., and then subjected to a heat treatment for drying, thereby forming a uniform resin layer in close contact with the substrate surface. As a heating device, a normal hot air circulating oven or an infrared heater, etc., can be used. The heating temperature and heating time are appropriately selected taking into consideration economic efficiency, etc.

The coating agent of the present invention has excellent coatability and is therefore capable of forming a resin layer with a sufficient thickness by a single coating step.
In addition, since the coating agent of the present invention has excellent film-forming properties, it is possible to suppress problems such as cracking and coating gaps (the occurrence of uncoated areas when coating a substrate), and to obtain a resin layer with excellent waterproofing and oil resistance. Furthermore, even when the formed resin layer is curved, the occurrence of problems such as cracking and coating gaps is suppressed.
Furthermore, since the resin layer formed from the coating agent of the present invention is excellent in both heat sealability and blocking resistance, the laminate described below has improved processability during molding.

<Laminate>
The laminate of the present invention is formed by laminating a paper substrate and a resin layer, and the resin layer contains an acid-modified polyolefin resin and one or more selected from a urethane resin, an acrylic resin, and a hydroxyl group-containing compound. The resin layer can be obtained by applying the coating agent of the present invention to the paper substrate and drying it.

The resin layer constituting the laminate of the present invention preferably has a thickness of 0.1 to 100 μm, more preferably 0.5 to 50 μm, and even more preferably 1 to 20 μm. A resin layer formed to have a thickness within the above range has excellent thickness uniformity.

To adjust the thickness of the resin layer, it is preferable to use a coating agent with a concentration suitable for the desired thickness, in addition to appropriately selecting the coating device and operating conditions. The concentration of the coating agent can be adjusted by the charge composition at the time of preparation, or it may be adjusted by appropriately diluting or concentrating the coating agent once prepared.

The paper substrate constituting the laminate of the present invention is manufactured by intertwining natural fibers such as those from plants, and examples of such substrates include fine paper, medium-quality paper, recycled paper, art paper, craft paper, roll paper, processed base paper, cloth paper, cardboard, and corrugated cardboard. The paper substrate may be surface-treated, and may have, for example, barrier properties or design properties imparted to the surface.

In order to impart required performance to the laminate of the present invention, a substrate such as a nonwoven fabric, or a layer such as a sealant layer, a printing layer, or a topcoat layer may be provided on the paper substrate surface or the resin layer surface of the laminate.
Examples of methods for providing these substrates and layers include known methods such as dry lamination via an adhesive layer, thermal lamination, heat sealing, and extrusion lamination.
Examples of the adhesive include one-liquid type urethane adhesives, two-liquid type urethane adhesives, epoxy adhesives, and aqueous dispersions of acid-modified polyolefin resins. The coating agent of the present invention may be used as the adhesive.

<Packaging materials, paper containers>
The laminate of the present invention can be used as a packaging material or a molding material for paper containers.
The laminate of the present invention can be molded by folding or rolling it into a cylindrical shape, overlapping the ends, and heat sealing, since the resin layer has excellent heat sealability. Since the laminate is made of a coating agent with excellent adhesion, the occurrence of cracks is suppressed even when it is bent or rolled into a cylindrical shape. Furthermore, even if the resin layers of the laminate overlap and come into contact with each other during processing, there is no blocking. The occurrence of is suppressed, that is, the moldability is excellent.
The resin layer of the laminate of the present invention has excellent moldability, and therefore food packaging materials and paper containers for containing food molded using the laminate of the present invention have excellent waterproof and oil resistance. It will be superior to
The form of the paper container is not particularly limited, and examples thereof include paper packaging, paper plates, paper cups, etc. The bottom of the paper cup is folded and the joint is fixed to form pleats, and the top The edges are rounded and glued during production, and the resin layer formed using the coating agent of the present invention can conform to such shapes and provide good heat sealing.

The present invention will be described in detail below with reference to examples, although the present invention is not limited to these.
Various characteristics were measured or evaluated by the following methods.

1. Melting point and glass transition temperature A 10 mg sample of the resin was measured using a DSC (differential scanning calorimetry) device (PerkinElmer, DSC7) at a heating rate of 10° C./min.

2. Viscosity of Coating Agent The rotational viscosity at a temperature of 25° C. was measured using a digital viscometer (DV2T, manufactured by Brookfield).

3. Coatability on Paper Substrate The thickness of the resin layer of the laminate was measured using a gauge sensor (GS-3813B, manufactured by Ono Sokki Co., Ltd.), and the coatability was evaluated according to the following criteria.
◯: Resin layer thickness is 5 μm or more △: Resin layer thickness is 3 μm or more and less than 5 μm ×: Resin layer thickness is less than 3 μm

4. Film-Forming Property The surface of the resin layer of the laminate was observed at a magnification of 200 times using an electron microscope (tabletop scanning electron microscope manufactured by Thermo Fisher Scientific), and the film-forming property was evaluated according to the following criteria.
○: No cracks or uncoated areas on the paper base. △: Cracks or uncoated areas on the paper base (not across the entire surface).
×: Cracks and uncoated areas on the paper base material are present over the entire surface.

5. Heat sealability (bonding strength)
The coating agent was applied to the paper substrate using a bar coater (No. 20) and then dried. The coated surfaces were then bonded together and heat-sealed for 5 seconds at a temperature of 150°C and a pressure of 0.2 MPa. The bonded surfaces of the bonded paper substrates were then peeled off in a 180° direction, and the heat-sealability was evaluated according to the following criteria.
○: Adheres well, and the paper is damaged when peeled off. △: Adheres, but can be easily peeled off. ×: Not adhered.

Water containing 0.3% by mass of blue pigment (EP-700 Blue GA, manufactured by Dainichi Seika Chemicals Co., Ltd.) was dropped onto the surface of the resin layer of the laminate, and the surface was wiped off after 5 minutes. The degree of coloring of the paper at that time was visually confirmed, and the waterproofness was evaluated according to the following criteria.
◎: No water droplets at all ○: Very few water droplets ×: Water droplets (water has penetrated)

7. Oil resistance A kit test was carried out according to the following method based on JAPAN TAPPI T599cm-02 paper pulp test method.
Test solutions (kit numbers 1 to 12) in which castor oil, toluene and n-heptane were mixed in different volume ratios were dropped onto the resin layer surface of the laminate. If spots were formed due to penetration of the oil droplets 15 seconds after dropping, the sample was judged as failing. The highest kit number that did not produce spots was regarded as the oil resistance of that sample, and the oil resistance was evaluated according to the following criteria.
◎: Oil resistance 10 or more ○: Oil resistance 8 to 9
△: Oil resistance level 5 to 7
×: Oil resistance level 4 or less

8. Blocking Resistance The resin layer surfaces of the laminates were brought into contact with each other and left to stand for one day under a load of 1 MPa in an atmosphere of 25° C. Thereafter, the samples were peeled off, and the blocking resistance was evaluated according to the following criteria.
◎: No blocking (no peeling resistance or peeling noise)
○: No force is required to peel off, but there is a peeling noise. △: Force is required to peel off (not adhered).
×: Adhered

The following materials were used as the coating agent raw materials and the paper base material.
1. Production of aqueous dispersion (E-1) of acid-modified polyolefin resin Using a stirrer equipped with a sealable pressure-resistant glass container equipped with a heater, 100 g of acid-modified polyolefin resin (ethylene-ethyl acrylate-maleic anhydride copolymer, maleic anhydride 2 mass%, melting point 105 ° C., glass transition temperature less than 0 ° C.), 100 g of isopropanol, 4.0 g of triethylamine, and 296 g of distilled water were charged into a glass container and heated to 120 ° C. with stirring to obtain a milky white polyolefin resin aqueous dispersion E-1 (solid content concentration about 20 mass%, viscosity 60 mPa s, isopropanol ratio in aqueous medium 25 mass%).

Preparation of aqueous dispersion (E-2) of acid-modified polyolefin resin 100 g of water and 2.0 g of dimethylethanolamine were added to 200 g of the aqueous dispersion (E-1) of acid-modified polyolefin resin, and then 102 g of the solvent was distilled off under reduced pressure using an evaporator to obtain an aqueous dispersion (E-2) of acid-modified polyolefin resin having an isopropanol ratio of less than 1 mass% in the aqueous medium (solid concentration of about 20 mass%, viscosity of 15 mPa·s).

2. Urethane resin/urethane resin emulsion: Mitsui Chemicals, Takelac W-6010, solid content concentration 30% by mass, glass transition temperature 90° C.

3. Acrylic resin/acrylic resin A emulsion: manufactured by DSM, NeoCryl A-6092, solid content concentration 43% by mass, glass transition temperature 56° C.
Acrylic resin B emulsion: NeoCryl A-1092, manufactured by DSM, solid content concentration 49% by mass, glass transition temperature 9°C

4. Hydroxyl-containing compound CMC: Carboxymethylcellulose, manufactured by Nippon Paper Industries Co., Ltd., Sunrose F350HC
Polysaccharides: Xanthan gum, manufactured by Danisco Japan, GRINDSTED Xanthan J
PVA: polyvinyl alcohol solution, 10% by mass solution of JMR-10L manufactured by Nippon Vinyl Polyvinyl Alcohol Co., Ltd. (solvent: water/isopropanol (mass ratio 40/60))

5. Paper base material: Nippon Paper Industries Co., Ltd., basis weight 230 g/ ^m2

Example 1
To 100 g of the acid-modified polyolefin resin aqueous dispersion (E-2), 20 g of the urethane resin emulsion (solid content mass ratio 100/30) and 7 g of isopropanol (isopropanol ratio in the aqueous medium 7% by mass) were added to prepare a coating agent.
The prepared coating liquid was applied onto a paper substrate using a bar coater (No. 20) and dried for 30 seconds in a hot air dryer set at 110°C to form a resin layer and prepare a laminate.

Examples 2 to 15, Comparative Examples 1 to 3
The types of the acid-modified polyolefin resin aqueous dispersion, the urethane resin, the acrylic resin, and the hydroxyl group-containing compound were changed, and the mass ratio of each solid content was also changed, as shown in Table 1. In addition, a coating agent was prepared by adding isopropanol to the aqueous medium so as to obtain the ratio shown in Table 1, and a laminate was prepared in the same manner as in Example 1.

The composition of the coating agents prepared in the examples and comparative examples, and the evaluation results of their various properties are shown in Table 1.

The coating agents obtained in Examples 1 to 15 were excellent in applicability to paper and film-forming properties, and the formed resin layers were excellent in heat sealability, waterproofness, and oil resistance.
In particular, in Examples 3 and 8, the types and contents of the urethane resin, acrylic resin and hydroxyl group-containing compound were preferable, and as a result, the formed resin layer had even more excellent properties such as waterproofness and oil resistance.

In Comparative Examples 1 to 3, the aqueous dispersions of acid-modified polyolefin resins that did not contain any of urethane resin, acrylic resin, or hydroxyl group-containing compounds were inferior in coatability and film-forming properties on paper, and the resin layers formed were inferior to those of the Examples in all of heat sealability, waterproofness, and oil resistance.

Claims (5)

An acid-modified polyolefin resin;
a urethane resin and/or an acrylic resin ;
A hydroxyl group-containing compound (excluding fibrous cellulose) ,
A coating agent comprising: an aqueous medium. The coating agent according to claim 1, characterized in that the content of the urethane resin and/or the acrylic resin is more than 10 parts by mass and not more than 100 parts by mass per 100 parts by mass of the acid-modified polyolefin resin. A laminate comprising a paper base material and a resin layer,
The resin layer comprises an acid-modified polyolefin resin,
a urethane resin and/or an acrylic resin ;
A laminate comprising: a hydroxyl group-containing compound (excluding fibrous cellulose) ; A packaging material comprising the laminate according to claim 3. A paper container comprising the laminate according to claim 3.