JP2001288404A - Water-base coating composition and polyolefin resin molding prepared by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-base coating composition that can form a polyester resin film adherently on the surface of a polyolefin resin material, and a polyolefin resin molding having a polyester resin film. SOLUTION: The water-base coating composition comprises a polyester resin (A) having an acid value of 10-40 mg/KOH and a weight average molecular weight of 9,000 or more, and an oxazoline-group-containing polymer (B).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous coating composition which is applied to a substrate to form a film having excellent water resistance and solvent resistance. The present invention relates to an aqueous coating composition that can form a film having good adhesion even when the coating composition is used.

[0002]

2. Description of the Related Art A high molecular weight polyester resin composed of a polybasic acid component and a polyhydric alcohol component is used as a film-forming resin as a resin for forming a film, resistance to an organic solvent (solvent resistance), weather resistance, and the like. Because of its excellent adhesiveness to various substrates, it is used in large quantities as a binder component in the fields of paints, inks, adhesives, coatings and the like. Particularly in recent years, the use of organic solvents has tended to be restricted from the standpoint of environmental protection, resource saving, regulation of dangerous substances by the Fire Service Law, etc., and improvement of the workplace environment. Development of an aqueous dispersion of a polyester resin finely dispersed in an aqueous medium has been actively performed.

For example, Japanese Patent Application Laid-Open No. 9-296100 discloses an aqueous polyester resin dispersion in which a polyester resin having an acid value of 10 to 40 mg KOH / g and a weight average molecular weight of 9,000 or more is dispersed in an aqueous medium. It is proposed that a film excellent in processability, water resistance, solvent resistance and the like can be formed by using such an aqueous dispersion.

[0004]

The above-mentioned aqueous dispersion of polyester resin can be used as a coating agent for various substrates, and can form a high-performance polyester resin film with good adhesion. Depending on
In some cases, the adhesion was not sufficient. In particular, when coating a material molded from a polyolefin resin that is used in large quantities as a general-purpose resin, such as a polypropylene film or a polyethylene film, the polyolefin resin originally has a low affinity for other substances. The adhesion of the polyester resin film was not sufficient. In addition, the low affinity of the polyolefin resin makes it difficult to print a polyolefin resin film or to form a multilayer film with different materials, for example.

[0005]

[Problems to be solved by the invention]

[0006] The present invention has been made in view of the above situation, and an aqueous coating composition capable of forming a polyester resin coating on a polyolefin resin material surface with good adhesion, and a polyolefin resin molded article having a polyester resin coating. It is an object to provide

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve such problems, and as a result, have found that a polyester resin having a controlled acid value and a weight average molecular weight, a polymer having an oxazoline group-containing polymer, The present inventors have found that a polyester resin coating film can be formed with good adhesion by preparing an aqueous coating composition in combination with the above and coating the polyolefin resin film with the aqueous coating composition.

That is, the gist of the present invention is, first, a polyester resin (A) having an acid value of 10 to 40 mg / KOH and a weight average molecular weight of 9000 or more, and an oxazoline group-containing polymer (B). An aqueous coating composition characterized by containing:

Secondly, there is provided a polyolefin resin molded article having a coating formed from the above coating composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The aqueous coating composition of the present invention comprises, in an aqueous medium, a polyester resin (A) having an acid value of 10 to 40 mg / KOH and a weight average molecular weight of 9000 or more.
And a oxazoline group-containing polymer (B). First, the polyester resin (A) will be described.

The acid component of the polyester resin (A) includes aromatic polybasic acids, aliphatic polybasic acids, alicyclic polybasic acids and the like. Examples of aromatic dicarboxylic acids among the aromatic polybasic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and the like, and examples of the aliphatic dicarboxylic acids among the aliphatic polybasic acids Examples include oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecane diacid, saturated dicarboxylic acids such as hydrogenated dimer acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, anhydride Examples include unsaturated dicarboxylic acids such as itaconic acid, citraconic acid, citraconic anhydride, and dimer acid. Examples of alicyclic dicarboxylic acids among alicyclic polybasic acids include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid,
Examples thereof include 2,5-norbornene dicarboxylic acid and its anhydride, tetrahydrophthalic acid and its anhydride, and the like. If necessary, a small amount of 5-sodium sulfoisophthalic acid, 5-hydroxyisophthalic acid, or the like can be used as an acid component as long as the water resistance of the coating is not impaired.

Among the above acid components, aromatic polybasic acids are preferable, and the ratio of the aromatic polybasic acid in the acid component of the polyester resin (A) is preferably 50 mol% or more, and more preferably 60 mol% or more. It is more preferably at least 70 mol%, particularly preferably at least 80 mol%. By increasing the proportion of the aromatic polybasic acid, the proportion of the aromatic skeleton in the resin skeleton that is less likely to be hydrolyzed than the aliphatic and alicyclic ester bonds increases, so that the film formed from the coating composition ( Hereinafter, referred to as resin coating)
This is preferred because the hardness, water resistance, and solvent resistance of the coating composition are improved, and the storage stability of the aqueous coating composition is improved.
Furthermore, among the above-mentioned aromatic polybasic acids, terephthalic acid can be improved in workability, hardness, water resistance, solvent resistance, weather resistance, etc. while balancing the various properties of the resin film. Is particularly preferred.

The acid component may be a tribasic or higher polybasic acid such as trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride. , Trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), 1,2,3,4-butanetetracarboxylic acid, and the like. At this time, from the viewpoint of maintaining good workability of the resin film, the proportion of the trifunctional or higher polybasic acid in the acid component of the polyester resin (A) is preferably 10 mol% or less, more preferably 8 mol% or less. It is preferably at most 5 mol%.

The alcohol component of the polyester resin (A) includes aliphatic glycols having preferably 2 to 10 carbon atoms, alicyclic glycols having preferably 6 to 12 carbon atoms, and ether bond-containing glycols. Examples of such aliphatic glycols include ethylene glycol,
1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-
Propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, etc. Examples of the alicyclic glycol include 1,4-cyclohexanedimethanol, and examples of the ether bond-containing glycol include diethylene glycol, triethylene glycol, and dipropylene glycol. When the ether structure is increased, the water resistance of the polyester resin and the weather resistance may be reduced.Therefore, the amount of the ether bond-containing glycol used may be limited to a range where the water resistance and the weather resistance of the resin film are not impaired. preferable. Further, glycols obtained by adding one to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols, such as 2,2-bis (4-hydroxyethoxyphenyl) propane, and polyethylene. Glycol, polypropylene glycol, polytetramethylene glycol and the like can be used as an alcohol component if necessary.

Among the above alcohol components, ethylene glycol or neopentyl glycol is particularly preferred. The total ratio of ethylene glycol and neopentyl glycol in the alcohol component of the polyester resin A is preferably 50 mol% or more, and more preferably 60 mol% or more. % Or more, more preferably 70 mol% or more. Ethylene glycol and neopentyl glycol are inexpensive because they are industrially produced in large quantities, and the various properties of the resin film are balanced.Ethylene glycol improves the chemical resistance of the resin film, and neopentyl glycol is In particular, it is advantageous as an alcohol component of the polyester resin (A) because it has an advantage of improving the weather resistance of the resin film.

The alcohol component may be a trifunctional or higher functional trihydric or higher polyhydric alcohol such as glycerin.
It may contain trimethylolethane, trimethylolpropane, pentaerythritol and the like. At this time,
In terms of maintaining good workability of the resin film, the proportion of the trifunctional or higher polyhydric alcohol in the alcohol component of the polyester resin (A) is preferably 10 mol% or less, more preferably 8 mol% or less, and 5 mol% or less. Molar% or less is particularly preferred.

The polyester resin (A) may contain lauric acid, myristic acid, palmitic acid,
Fatty acids such as stearic acid, oleic acid, linoleic acid and linolenic acid and ester-forming derivatives thereof, benzoic acid, p-
tert-butylbenzoic acid, cyclohexanoic acid, high-boiling monocarboxylic acids such as 4-hydroxyphenylstearic acid, stearyl alcohol, high-boiling monoalcohols such as 2-phenoxyethanol, ε-caprolactone,
Hydroxycarboxylic acids such as lactic acid, β-hydroxybutyric acid, p-hydroxybenzoic acid and the like and ester-forming derivatives thereof may be copolymerized.

The acid value of the polyester resin (A) is as follows:
10 to 40 mg KOH / g, and 10 to 30 mg KO
H / g is preferable, and 10 to 25 mgKOH / g is more preferable. When the acid value exceeds 40 mgKOH / g, the water resistance and the solvent resistance of the resin film become insufficient. On the other hand, when the acid value is 1
If it is less than 0 mgKOH / g, it is difficult to disperse the polyester resin in the aqueous medium, and it is difficult to obtain a uniform aqueous coating composition. As a result, the water resistance and the solvent resistance of the resin film become insufficient.

The weight average molecular weight of the polyester resin (A) is at least 9,000, preferably at least 11,000, more preferably at least 13,000. If the weight average molecular weight is less than 9,000,
The water resistance and solvent resistance of the resin film are insufficient, and the workability of the resin film is insufficient. The upper limit of the weight average molecular weight is preferably 45,000 or less, and more preferably 40,000 or less, from the viewpoint that the polyester resin (A) is easily imparted with a sufficient acid value and the viscosity of the aqueous coating composition is appropriately maintained. More preferably, it is particularly preferably 35,000 or less.

The polyester resin (A) may contain a hydroxyl group, and the hydroxyl value of the polyester resin (A) is preferably 30 mgKOH / g or less, more preferably 2 mgKOH / g or less.
0 mgKOH / g or less is more preferable, and 15 mgKOH / g
/ G or less is particularly preferred.

Further, the glass transition temperature (abbreviated as T _g ) of the polyester resin (A) is not particularly limited, but from the viewpoint that the hardness of the resin film and the workability are easily balanced. 0-90 ° C is preferred, and 30-
80 ° C. is more preferred.

The polyester resin (A) can be produced by usual polycondensation of at least one of the above-mentioned acid components and at least one of the alcohol components. Examples of known methods that can be used for the production of the polyester resin (A) are as follows: (a) All the monomer components and / or low polymers thereof are reacted at 180 to 250 ° C., 2.5
The esterification reaction is carried out by reacting for about 10 to 10 hours, and then the polycondensation reaction is advanced at 220 to 280 ° C. under a reduced pressure of 130 Pa or less at a temperature of 220 to 280 ° C. until a desired molecular weight is reached in the presence of a transesterification catalyst. (B) terminating the polycondensation reaction at a stage before the target molecular weight is reached, and converting the reaction product to a chain selected from an epoxy compound, an isocyanate compound, a bisoxazoline compound and the like in the next step (C) proceeding the polycondensation reaction to a stage at or above the target molecular weight, further adding a monomer component, and adding an inert atmosphere And a method of obtaining a polyester resin having a target molecular weight by performing depolymerization at a normal pressure to a pressure system.

It is preferable that the carboxyl group contributing to the aqueous conversion of the polyester resin (A) is unevenly distributed at the terminal of the resin molecular chain rather than in the resin skeleton from the viewpoint of the hot water resistance of the coating. As a method for obtaining such a polyester resin without a side reaction or gelation, a method in which a polybasic acid having three or more functional groups or an ester-forming derivative thereof is added after the start of the polycondensation reaction in the above method (a). Or a method in which an acid anhydride of a polybasic acid is added immediately before the end of the polycondensation reaction. In the above method (b), a low molecular weight polyester resin in which most of the molecular chain ends are carboxyl groups is used as a chain extender. Or a method in which a polybasic acid or an ester-forming derivative thereof is used as a depolymerizing agent in the above method (c).

Next, the oxazoline group-containing polymer (B) will be described. The oxazoline group-containing polymer (B) used in the present invention is not particularly limited as long as it is a polymer having an oxazoline group. Also,
As the oxazoline group-containing polymer (B), one kind may be used, or two or more kinds may be used in combination. The oxazoline group is a functional group represented by the following general formula (1).

[0025]

Embedded image (In the formula, R ₁ , R ₂ , R ₃ , and R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, a cycloalkenyl group, an aryl group, or a substituted aryl group. )

The oxazoline group-containing polymer can be easily obtained by polymerizing a monomer composition containing an oxazoline derivative, as described in, for example, JP-A-9-328656. As such oxazoline derivatives, for example, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-2-oxazoline,
Vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-
Methyl-2-oxazoline, 2-isopropenyl-5-
Methyl-2-oxazoline, 2-isopropenyl-5-
Ethyl-2-oxazoline and the like can be mentioned, and among these oxazoline derivatives, 2-isopropenyl-2-oxazoline is particularly preferable because it is industrially easily available.

The monomers other than the oxazoline derivative contained in the monomer composition containing the oxazoline derivative are copolymerized with the oxazoline derivative, and
Any compound that is inert to the oxazoline group may be used,
Although not particularly limited, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t- (meth) acrylate Butyl, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic acid-2- Hydroxyethyl, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monoester of (meth) acrylic acid with polypropylene glycol or polyethylene glycol, (meth)
2-aminoethyl acrylate and its salts, (meth)
(Meth) acrylic acid such as caprolactone-modified acrylic acid, (meth) acrylic acid-2,2,6,6-tetramethylpiperidine, (meth) acrylic acid-1,2,2,6,6-pentamethylpiperidine Acid esters; sodium (meth) acrylate, potassium (meth) acrylate,
(Meth) acrylic acid salts such as ammonium (meth) acrylate; unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth) acrylamide, N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) Unsaturated amides such as acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; and halogen-containing compounds such as vinyl chloride, vinylidene chloride and vinyl fluoride. α, β-unsaturated aliphatic hydrocarbon; α, β such as styrene, α-methylstyrene, sodium styrenesulfonate, etc.
β-unsaturated aromatic hydrocarbons; and the like.

In the oxazoline group-containing polymer (B), the proportion occupied by the structural unit derived from the oxazoline derivative is preferably 5% by mass or more.
When the proportion of the structural unit derived from the oxazoline derivative is 5% by mass or more, the hardness, water resistance, and water resistance of the resin film are increased by the reaction between the structural unit and a carboxyl group or a carboxylic anhydride group of the polyester resin (A). It is preferable because the solvent property can be improved.

The oxazoline group-containing polymer (B) is preferably aqueous (water-soluble or water-dispersible). Specific examples of preferred aqueous oxazoline group-containing polymers that can be used in the present invention include Nippon Shokubai Co., Ltd., Epocross WS-500, Epocross WS-700, Epocross K1010E, Epocross K1020E, Epocross K1030E, Epocross K2010E, Epocross K2010E. K2020E, Epocross K
It can be obtained under brands such as 2030E.

When the oxazoline group-containing polymer (B) is contained in the aqueous coating composition of the present invention, the adhesion of the resin film to the polyolefin resin material is improved, although the reason is not clear. In addition, by reacting with the carboxyl group or carboxylic anhydride group of the polyester resin (A) as described above, there is also an effect of improving the performance of the resin film. In addition, even when the unreacted oxazoline group-containing polymer (B) remains in the resin film, the performance of the resin film is not significantly reduced because the polymer is a polymer.

In the aqueous coating composition of the present invention, the polyester resin (A) and the oxazoline group-containing polymer (B) are dispersed or dissolved in an aqueous medium. Here, the aqueous medium is a medium composed of a liquid containing water as a main component, and may contain a basic compound or an organic solvent described later.

In the aqueous coating composition of the present invention, the total content of the content of the polyester resin (A) and the content of the oxazoline group-containing polymer (B) is determined by the film forming conditions and the purpose. It can be appropriately selected depending on the thickness and performance of the resin film, and is not particularly limited,
From the viewpoint of appropriately maintaining the viscosity of the coating composition and expressing good film-forming ability, 1 to 60% by mass is preferable,
3 to 55% by mass is more preferable, 5 to 50% by mass is more preferable, and 10 to 45% by mass is particularly preferable.

The mass ratio (A) / (B) between the polyester resin (A) and the oxazoline group-containing polymer (B) in the aqueous coating composition of the present invention is defined as the properties of the polyester resin (A), It may be appropriately determined according to the properties of the group-containing polymer (B), and also the properties of other components to be blended as necessary, and is not particularly limited. The range represented by the following formula (2) is preferable from the viewpoint of improving workability and expressing good workability, and the following formula (3)
Is more preferable, and the range expressed by the following formula (4) is particularly preferable.

(A) / (B) = 95/5 to 60/40 (2) (A) / (B) = 92/8 to 63/37 (3) (A) / (B) = 90/10 ~ 65/35 (4)

In the aqueous coating composition of the present invention, the carboxyl group of the polyester resin (A) is preferably neutralized by a basic compound, and aggregation between fine particles is caused by electric repulsion between generated carboxyl anions. To provide stability to the aqueous coating composition. As the basic compound used for such a purpose, an organic amine having a boiling point of 250 ° C. or lower, more preferably 160 ° C. or lower, or ammonia is preferable because it is easily volatilized at the time of film formation. Specific examples of preferably used organic amines include triethylamine, N, N-diethylethanolamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N
-Diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine, 3
-Ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine, Morpholine, N-methylmorpholine, N-ethylmorpholine and the like.

The amount of the basic compound to be used is, according to the amount of the carboxyl group contained in the polyester resin (A), an amount capable of at least partially neutralizing the carboxyl group, that is, 0.1 to the carboxyl group. 2-1.5 equivalents are preferable, and 0.4-1.3 equivalents are more preferable. When the use amount of the basic compound is 0.2 equivalent or more, dispersion stability can be sufficiently imparted, and when the use amount is 1.5 equivalent or less, the aqueous coating composition is not remarkably thickened.

In dispersing or dissolving the polyester resin (A) in an aqueous medium (hereinafter referred to as “water-based”), when water-soluble organic solvent is used in addition to water and the above-mentioned basic compound, water-based conversion is achieved. This is preferable because it is performed promptly. Here, the water-soluble organic solvent refers to an organic solvent having a solubility in water at 20 ° C. of 5 g / L or more, preferably 10 g / L or more. The boiling point of the water-soluble organic solvent is preferably 250 ° C. or lower, more preferably 150 ° C. or lower, since the lower the boiling point, the easier it is to volatilize from the resin film by drying.

In the present invention, the polyester resin (A)
Specific examples of the organic solvent preferably used for making the compound aqueous include ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-
Alcohols such as 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 , Methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, ketones such as isophorone,
Ethers such as tetrahydrofuran and dioxane, ethyl acetate, -n-propyl acetate, isopropyl acetate, -n-butyl acetate, isobutyl acetate, -sec-butyl acetate, -3-methoxybutyl acetate, methyl propionate,
Ester such as ethyl propionate, diethyl carbonate, dimethyl carbonate, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether Glycol derivatives such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, and propylene glycol methyl ether acetate;
-Methoxy-3-methylbutanol, 3-methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate, and the like.
A mixture of more than one species may be used.

The content of the water-soluble organic solvent in the aqueous coating composition is preferably 30% by mass or less, more preferably 25% by mass or less, and 20% by mass or less.
% By mass or less is more preferable. When the content of the organic solvent is in the above range, the film-forming ability, viscosity, and storage stability of the aqueous coating composition can be favorably maintained.
The content of the water-soluble organic solvent may be adjusted to a desired content by removing the water-soluble organic solvent by azeotropy or the like in the process after converting the polyester resin (A) into an aqueous solution. At this time, by using a water-soluble organic solvent having a boiling point of 100 ° C. or less or an azeotrope with water,
It is preferable because the organic solvent can be easily removed from the aqueous coating composition.

Further, a compound having a protective colloid action may be added to the aqueous coating composition of the present invention, if necessary. The protective colloid action means that the resin particles are adsorbed on the surface of the resin particles in the aqueous medium, exhibiting the so-called "mixing effect", "osmotic pressure effect", and "volume limiting effect". Refers to the action of preventing. Compounds having such a protective colloid action include polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, modified starch, polyvinylpyrrolidone, polyacrylic acid, acrylic acid and / or vinyl monomer having methacrylic acid as one component. Polymer, polyitaconic acid,
Gelatin, gum arabic, casein, swellable mica and the like can be exemplified.

The aqueous coating composition of the present invention may further contain, if necessary, various agents such as a leveling agent, an antifoaming agent, an anti-bake agent, a pigment dispersant, an ultraviolet absorber, titanium oxide, zinc oxide, and carbon dioxide. A pigment or dye such as black may be added.

In the present invention, the method for producing the aqueous coating composition is not particularly limited, and the polyester resin (A) and the oxazoline group-containing polymer (B) are charged together in an aqueous medium. May be carried out, and the polyester resin (A) may be made aqueous first, and the oxazoline group-containing polymer (B) may be added thereto in two steps.

Hereinafter, a preferred method for performing the above two steps will be described in detail. First, a device is provided which is provided with a tank into which a liquid can be charged and which can appropriately stir a mixture of the aqueous medium and the resin powder or the granular material charged into the tank. As such a device, a device widely known to those skilled in the art as a solid / liquid stirring device or an emulsifying device can be used. Usually, a simple lid is provided and used under normal pressure or slight pressure. However, if necessary, a device capable of applying a pressure of 0.1 MPa or more can be used. An aqueous medium comprising water, a basic compound and a water-soluble organic solvent, and a granular or powdery polyester resin (A) are charged into a tank of this apparatus, and the mixture is preferably stirred and mixed at a temperature of 40 ° C. or lower to obtain a crude mixture. Disperse. At this time, when the shape of the polyester resin is a sheet or a large lump in which coarse dispersion is difficult, the process may be shifted to the following heating step. Next, the temperature in the tank was set to be equal to or higher than Tg of the polyester resin or 40 ° C.
The polyester resin (A) is made sufficiently water-soluble by maintaining stirring at the above temperature, preferably for 15 to 120 minutes, and then cooled preferably to 40 ° C. or lower under stirring.

After this, a jet pulverizing process may be further performed if necessary. The jet crushing process here means that a fluid such as a polyester resin dispersion is ejected from a fine hole such as a nozzle or a slit under high pressure, and resin particles or resin particles collide with a collision plate or the like. This is to further reduce the size of the resin particles by mechanical energy. P. V.
GAULIN's “homogenizer”, Mizuho Industry's “Microfluidizer M-110E / H” and the like. Further, if necessary, the organic solvent added above can be removed by azeotropic distillation or the like. As described above, an aqueous dispersion or solution of the polyester resin (A) is obtained.

Then, while stirring the aqueous dispersion or solution of the polyester resin (A), a predetermined amount of the oxazoline group-containing polymer (B) and, if necessary, other additives are added and mixed. The aqueous coating composition of the present invention can be produced. In this case, when it is difficult to uniformly disperse the whole by low-speed stirring, a stirrer such as a homomixer to which a high shear force is applied at a high speed may be used.
If necessary, an organic solvent or water can be added for the purpose of lowering the viscosity of the system and improving the dispersibility of the oxazoline group-containing polymer (B) and the additives.

As described above, the aqueous coating composition of the present invention is prepared by dispersing or dissolving the polyester resin (A) and the oxazoline group-containing polymer (B) in an aqueous medium to prepare a uniform liquid. can get. Here, the term “homogeneous liquid” means that, in appearance, a portion where the solid content concentration is locally different from other portions, such as precipitation, phase separation or skinning, is not found in the aqueous coating composition. Say that. Further, it is preferable that coarse particles are not contained in the aqueous coating composition immediately after preparation. Here, the coarse particles specifically mean that the aqueous coating composition is subjected to pressure filtration (air pressure 0.2MP) using a 300 mesh stainless steel filter (wire diameter 0.035mm, plain weave).
The particles that remain on the filter when a) is performed. For the purpose of preventing coarse particles from being mixed into the aqueous coating composition, the above-described filtration or the like may be performed during the production process.

The coating composition of the present invention includes:
A small amount of precipitate or precipitate may occur during storage after preparation. It is considered that this precipitate or precipitate is generated by a partial reaction between the polyester resin (A) and the oxazoline group-containing polymer (B). You can remove it.

Next, a method for using the aqueous coating composition of the present invention will be described. Since the aqueous coating composition of the present invention is excellent in film forming ability, it can be uniformly formed on various substrate surfaces by a known film forming method, for example, a dipping method, a brush coating method, a spray coating method, a curtain flow coating method, or the like. After coating and setting as necessary at around room temperature, a uniform resin film can be formed in close contact with the surface of various substrates by subjecting it to heat treatment for drying or drying and baking. As a heating device at this time, a normal hot air circulation type oven, an infrared heater, or the like may be used. The heating temperature and the heating time are appropriately selected depending on the characteristics of the oxazoline group-containing polymer (B) and the characteristics of the substrate to be coated. Is preferably 30 to 250 ° C, more preferably 60 to 200 ° C, particularly preferably 90 to 160 ° C, and the heating time is preferably 1 second to 20 minutes, more preferably 5 seconds to 10 minutes, and more preferably 10 seconds. Especially preferred is -5 minutes. When the above-mentioned precipitates and precipitates are generated in the coating composition before use, it is preferable to use the coating composition in a state where these are removed.

The thickness of the resin film formed by using the aqueous coating composition of the present invention is appropriately selected depending on the use, but is preferably 0.01 to 100.
μm is preferable, and 0.1 to 50 μm is more preferable.
Particularly preferred is 0.5 to 25 μm. If the film is formed so that the thickness of the resin film is in the above range, a resin film having excellent uniformity can be obtained. In addition, in order to adjust the thickness of the resin film, in addition to appropriately selecting an apparatus to be used for the coating and its use conditions, an aqueous coating composition having a concentration suitable for the intended thickness of the resin film is used. Is preferred. As a method of adjusting the concentration at this time, the concentration may be adjusted to a desired concentration according to the charged composition at the time of preparation, or the aqueous coating composition once prepared may be diluted to a desired concentration.

The aqueous coating composition of the present invention does not require a high temperature exceeding 150 ° C. for heat treatment at the time of film formation and has excellent affinity with polyolefin resin materials. For example, it is particularly suitable for coating films and sheets made of polypropylene resins and polyethylene resins and modified products thereof. It is preferable that the surface of the polyolefin resin molded article to be coated be subjected to corona treatment in advance, since the adhesion of the resin film is further improved.

By forming a resin film on a polyolefin resin molded article as described above using the aqueous coating composition of the present invention, a polyolefin resin molded article having the film of the present invention can be obtained. The polyolefin resin molded article having the coating of the present invention has improved printability and affinity with other materials due to the action of the resin coating on the surface,
Multilayering with other materials is also easy.

[0052]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In addition, various characteristics were measured or evaluated by the following methods.

(1) Composition of polyester resin 1 Determined by ¹ H-NMR analysis (Varian, 300 MHz). In addition, the resin containing the constituent monomer having no peak that can be assigned or determined on the ¹ H-NMR spectrum is subjected to methanol decomposition in a sealed tube at 230 ° C. for 3 hours, and then subjected to gas chromatogram analysis and quantitative analysis. Was done.

(2) Acid value of polyester resin 0.5 g of polyester resin is dissolved in 50 ml of water / dioxane = 10/1 (volume ratio), titrated with KOH using cresol red as an indicator, and consumed for neutralization. KO
The value obtained by converting the mg number of H per 1 g of the polyester resin was determined as the acid value. (3) Hydroxyl value of polyester resin 3 g of the polyester resin was precisely weighed, 0.6 ml of acetic anhydride and 50 ml of pyridine were added, and the mixture was stirred and reacted at room temperature for 48 hours. Subsequently, 5 ml of distilled water was added. 6 more
By continuing stirring for a period of time at room temperature, all acetic anhydride not used in the above reaction was also changed to acetic acid. 50 ml of dioxane is added to this solution, and cresol red
Titration with KOH using thymol blue as an indicator. The amount of KOH consumed for neutralization (W ₁ ) and the amount of acetic anhydride initially charged did not react with the polyester resin. From the amount of KOH required for the sum (calculated value: W ₀ ), the difference (W ₀ -W ₁ ) was determined by the number of mg of KOH, and this value was divided by the number of g of the polyester resin to obtain a hydroxyl value. And

(4) Weight average molecular weight of polyester resin The weight average molecular weight was determined by GPC analysis (using a liquid sending unit LC-10ADvp type and a UV-visible spectrophotometer SPD-6AV type manufactured by Shimadzu Corporation), detection wavelength: 254 nm, Solvent: tetrahydrofuran, converted to polystyrene). (5) Glass transition temperature of polyester resin 10 mg of polyester resin was used as a sample, and a DSC (differential scanning calorimetry) device (DSC manufactured by PerkinElmer) was used.
The measurement is performed under the condition of a heating rate of 10 ° C./min using 7),
The intermediate value of the temperatures at the two bending points derived from the glass transition in the obtained temperature rise curve was determined and defined as the glass transition temperature (T _g ).

(6) Solid Content Concentration of Aqueous Dispersion of Polyester Resin An appropriate amount of the polyester dispersion was weighed and heated at 150 ° C. until the mass of the residue (solid content) reached a constant weight. I asked.

(7) Thickness of Resin Coating Thickness gauge (MICROFIN, manufactured by Union Tool Co., Ltd.)
E)), the thickness of the substrate (polypropylene film in the example) is measured in advance, and a resin film is formed on the substrate using the aqueous coating composition. Was measured in the same manner, and the difference was defined as the thickness of the resin film. (8) Adhesion of resin film The film film formed on the polypropylene film
Adhesive tape specified in IS Z1522 (width 18m
m) was adhered leaving an end portion, and rubbed with an eraser from above to sufficiently adhere the end portion. Then, the end portion of the adhesive tape was made perpendicular to the film and then instantaneously peeled off. The peeled adhesive tape surface is subjected to surface infrared spectroscopy (SYSTEM2000, Ge60 ゜ 5 manufactured by PerkinElmer).
By using a 0 × 20 × 2 mm prism), it was checked whether or not a resin film had adhered to the adhesive tape surface, and the adhesion of the resin film to the polypropylene film was evaluated according to the following criteria. ：: No peak derived from the resin film is observed on the adhesive tape surface. X: A peak derived from the resin film is observed on the surface of the adhesive tape.

The polyester resins used in Examples and Comparative Examples were obtained as follows.

[Polyester Resin A-1] A mixture of 1,578 g of terephthalic acid, 83 g of isophthalic acid, 374 g of ethylene glycol and 730 g of neopentyl glycol was heated in an autoclave at 260 ° C. for 2.5 hours to carry out an esterification reaction. went. Then, 0.262 g of germanium dioxide as a catalyst was added, and the temperature of the system was set to 3
The temperature was raised to 280 ° C. in 0 minutes, and then the pressure of the system was gradually reduced to 13 Pa after 1 hour. Under this condition, the polycondensation reaction was further continued. After 1.5 hours, the system was returned to normal pressure with nitrogen gas. When the temperature of the system was lowered to 250 ° C., 50 g of isophthalic acid and 38 g of trimellitic anhydride were added. ,
After stirring at 255 ° C. for 30 minutes, the resin was discharged in a sheet form. Then, after sufficiently cooling this to room temperature, the resin is pulverized with a crusher, and the opening is 1 to 6 mm using a sieve.
Was collected to obtain a granular polyester resin A-1.

[Polyester Resins A-2 and A-3] In the same manner as the above-mentioned polyester resin A-1, the composition of the acid component and the alcohol component was changed so as to be as shown in Table 1. And polyester resins A-2 and A-3.

Table 1 shows the results of analyzing and evaluating the type and amount of the depolymerizing agent used in the production and the characteristics of the obtained polyester resin for each of the polyester resins obtained as described above. Show.

[0062]

[Table 1]

Using the above polyester resin, an aqueous polyester resin dispersion was obtained by the following method.

[Polyester Resin Aqueous Dispersion E-1] 300 g of a stirrer (TK Robomix, manufactured by Tokushu Kika Kogyo Co., Ltd.) equipped with a jacketed and sealable 2 liter glass container was used. Polyester resin A-1,
150 g of isopropyl alcohol, 16.4 g of triethylamine and 534 g of distilled water were charged into a glass container, and the rotation speed of a stirring blade (homodisper) was set at 7,00.
When the mixture was stirred at 0 rpm, no sedimentation of resin particles was observed at the bottom of the container, and it was confirmed that the container was completely suspended. Then, while maintaining this state, the heated water was passed through the jacket after 10 minutes. Then, the temperature in the system was maintained at 73 to 75 ° C., and the mixture was further stirred for 30 minutes. After that, cool water was flown into the jacket, and the rotation speed was set to 4,000.
rpm and cooled to room temperature (about 25 ° C.) with stirring to obtain a milky white uniform aqueous dispersion of polyester resin E-1.
I got

[Polyester Resin Aqueous Dispersions E-2 and E-3] The same operation as that for obtaining the above polyester resin aqueous dispersion E-1 was carried out using the charged compositions shown in Table 2 below to obtain polyesters. Resin aqueous dispersions E-2 and E
-3 was obtained.

Table 2 below shows the charged composition for obtaining the above-mentioned aqueous polyester resin dispersion, and the solid concentration measured for the obtained aqueous polyester resin dispersion.

[0067]

[Table 2]

Example 1 100 g of the polyester resin aqueous dispersion E-1 was weighed,
While stirring this with a low-speed stirrer (MDS-NS, manufactured by EYELA), an aqueous solution containing an oxazoline group-containing polymer, Epocross WS-500 (manufactured by Nippon Shokubai Co., Ltd., solid content: about 40% by mass) Oxazoline equivalent: about 220 g · solid / eq) was gradually added, and the mixture was stirred and mixed at room temperature (about 25 ° C.) for about 5 minutes. Next, 100 g of distilled water was added, and the mixture was further stirred and mixed at room temperature (about 25 ° C.) for about 5 minutes to prepare and obtain an aqueous coating composition. The appearance of the aqueous coating composition was visually observed and found to be uniform without any precipitation or layer separation. Next, a 20 μm-thick stretched polypropylene film (OP-U1 manufactured by Tosello Co., Ltd.) whose surface was subjected to corona treatment was prepared, and the above aqueous coating composition was coated thereon with a tabletop type coating apparatus (Yasuda Seiki Co., Ltd .; Film applicator No. 542-A
After coating using B type, bar coater)
By heating for 2 minutes in an oven set at 110 ° C., a 1 μm thick resin film was formed on the polypropylene film.

Examples 2 to 6 Precipitation and layer separation were carried out in the same manner as in Example 1 except that the type and amount of the aqueous polyester resin dispersion and the amount of Epocros WS-500 were changed to the conditions shown in Table 3 below. Was prepared, and a 1 μm-thick resin film was formed on a polypropylene film.

Comparative Example 1 100 g of aqueous polyester resin dispersion B-1 was weighed,
While stirring this with a low-speed stirrer (manufactured by EYELA, MDS-NS), 100 g of distilled water was added, and the mixture was further stirred and mixed at room temperature (about 25 ° C.) for about 5 minutes to contain the oxazoline group-containing polymer. An aqueous coating composition was prepared. Using this, a resin coating having a thickness of 1 μm was formed on the polypropylene film by the same operation as in Example 1.

Comparative Examples 2 and 3 By changing the type of the aqueous dispersion of the polyester resin,
An aqueous coating composition containing no oxazoline group-containing polymer was prepared in the same manner as in Comparative Example 1 except that the composition shown in Table 1 was used, and a resin film having a thickness of about 1 μm was formed on a polypropylene film.

Table 3 below shows the composition of the aqueous coating compositions prepared in the above Examples and Comparative Examples, and the results of examining the adhesiveness of the resin film formed on the polypropylene film.

[0073]

[Table 3]

From the above Examples and Comparative Examples, it is understood that the aqueous coating composition of the present invention can form a high molecular weight polyester resin film having excellent adhesion to a polyolefin resin by the action of the oxazoline group-containing polymer. Was.

[0075]

The aqueous coating composition of the present invention can form a high molecular weight polyester resin film excellent in water resistance, solvent resistance and processability, so that it can be used for paints, adhesives, surface treatment agents, inks and fiber treatments. Agent, paper coating agent, various coating agents or binder components thereof. In particular, the coating formed from the aqueous coating composition of the present invention has excellent adhesion to the polyolefin resin.For example, a material having poor adhesion to a substrate made of a polyolefin resin such as a polypropylene resin film is used. The aqueous coating composition of the present invention can be suitably used as an anchor coating agent for laminating. Further, the polyolefin resin molded article having a coating formed from the coating composition of the present invention has improved printability and adhesion to other materials due to the action of the coating on the surface. It can be suitably used as various packaging materials by laminating with other materials.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // C08L 67:00 C08L 67:00 (72) Inventor Sachiko Kokuryo 23 Uji Kozakura, Uji City, Kyoto Unitika F-term in the Central Research Laboratories of Stock Company (reference) NA12 NA13 PA19 PB04 PB05 PB07 PC08

Claims (4)

[Claims] 1. An aqueous coating comprising a polyester resin (A) having an acid value of 10 to 40 mg / KOH and a weight average molecular weight of 9000 or more, and an oxazoline group-containing polymer (B). Composition. 2. The aqueous coating composition according to claim 1, wherein the polyester resin (A) is a polyester resin containing at least 50 mol% of an aromatic polybasic acid as a constituent acid component. 3. The aqueous coating composition according to claim 1, wherein the polyester resin (A) is a polyester resin mainly comprising neopentyl glycol and ethylene glycol as constituent alcohol components. 4. A polyolefin resin molded article having a coating formed from the aqueous coating composition according to claim 1.