JP2012246457A - Aqueous coating material for plastic substrate, coating and plastic molded product including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating material for plastic substrates having good adhesive property for plastic substrates especially for both an ABS substrate and a polypropylene substrate, and giving a coating that is excellent in water resistance.SOLUTION: The aqueous coating material includes an aqueous emulsion ( I ) having a weight average molecular weight of 80,000 or less, and a chlorinated polyolefin resin (II). The aqueous emulsion ( I ) is prepared by emulsion polymerization of an emulsion that is prepared by emulsion polymerization of a monomer mixture (A) that contains a cyano group-containing vinyl monomer (a1), a vinyl monomer (a2) that contains a hydroxy group having a carbon number of four or more, and another copolymerizable vinyl monomer (a3), and by adding to the emulsion another monomer mixture (B) that contains a cyano group-containing vinyl monomer (b1), a vinyl monomer (b2) that contains a hydroxy group having a carbon number of four or more, an acid-containing vinyl monomer (b3), and another copolymerizable vinyl monomer (b4) to further perform emulsion polymerization.

Description

 The present invention relates to an aqueous coating material for a plastic substrate, a paint containing the same, and a plastic molded product.

In general, a solvent-type coating material using an organic solvent as a medium has been used in order to maintain the surface protection and aesthetics of substrates such as metal, wood, paper, and plastic. In recent years, there has been a demand for a shift from a solvent-type coating material to an aqueous coating material using water as a medium in order to improve the painting work environment.
Solvent-type coating material, when applied to a plastic base material, the organic solvent in the coating material dissolves the surface of the base material very slightly, thereby exhibiting adhesion between the coating film and the base material. Have In the case of an aqueous coating material, such an effect cannot be expected, so that sufficient adhesion has not been obtained.
For this reason, various aqueous coating materials according to the material of the substrate have been studied for the purpose of improving adhesion.

In recent years, polypropylene (PP) base materials have been widely used from the viewpoint of cost reduction and recyclability, and chlorinated polypropylene resins are widely used as water-based coating materials in order to improve adhesion to PP base materials. For example, in order to improve adhesion to a PP base material, an aqueous coating composition for automobile interior materials including a single-layer resin emulsion containing a chlorinated polyolefin resin has been proposed (for example, Patent Document 1).
In order to improve the adhesion to the ABS substrate, a coating resin composition containing a resin emulsion having a so-called core-shell structure has been proposed (for example, Patent Document 2).

JP 2001-2777 A JP 2008-260851 A

However, the invention of Patent Document 1 does not have sufficient adhesion to the ABS substrate. On the other hand, the invention of Patent Document 2 does not have sufficient adhesion to the PP substrate.
In addition, the coating film formed of the aqueous coating material is required to have water resistance, which is its basic performance.
Accordingly, the present invention provides an aqueous coating for a plastic substrate, which has a good adhesion to a plastic substrate, particularly an ABS substrate and a PP substrate, and provides a coating film excellent in water resistance. Intended for materials.

 As a result of intensive studies, the present inventors have found that the use of a cyano group-containing vinyl monomer increases adhesion to a plastic substrate and water resistance. In addition, by using a hydroxyl group-containing vinyl monomer having 4 or more carbon atoms, it has been found that adhesion to both the ABS base material and the PP base material is improved, and the present invention has been achieved.

That is, the water-based coating material for a plastic substrate of the present invention comprises 3 to 30% by mass of a cyano group-containing vinyl monomer (a1) and a hydroxyl group-containing vinyl monomer (a2) 1 having 4 or more carbon atoms. 10% by mass and a monomer mixture (A) containing other copolymerizable vinyl monomers (a3) {however, the sum of (a1) to (a3) is 100% by mass} The emulsion thus obtained contains 5 to 50% by mass of a cyano group-containing vinyl monomer (b1), 1 to 30% by mass of a hydroxyl group-containing vinyl monomer (b2) having 4 or more carbon atoms, and an acid group. Monomer mixture (B) containing 1 to 30% by mass of the vinyl-containing monomer (b3) and the other copolymerizable vinyl monomer (b4) {provided that (b1) to (b4) The total is 100% by mass} and is obtained by emulsion polymerization, and the weight average molecular weight is 80,000 or less. And sex emulsion (I), characterized in that it contains a chlorinated polyolefin resin (II), the.
The mass ratio represented by the aqueous emulsion (I) / chlorinated polyolefin resin (II) is preferably 50/50 to 95/5.

  The paint of the present invention is characterized by including the aqueous coating material for the plastic substrate of the present invention.

  The plastic molding of the present invention is characterized in that the paint of the present invention is applied.

  According to the water-based coating material for a plastic substrate of the present invention, a coating film having good adhesion to a plastic substrate, particularly an ABS substrate and a PP substrate, and having excellent water resistance can be obtained. It is done.

(Water-based coating material for plastic substrates)
The aqueous coating material for a plastic substrate of the present invention (hereinafter sometimes simply referred to as an aqueous coating material) contains an aqueous emulsion (I) and a chlorinated polyolefin resin (II).

<Water-based emulsion (I)>
The aqueous emulsion (I) of the present invention is obtained by emulsion polymerization of the monomer mixture (B) in an emulsion obtained by emulsion polymerization of the monomer mixture (A).

≪Monomer mixture (A) ≫
The monomer mixture (A) includes a cyano group-containing vinyl monomer (a1), a hydroxyl group-containing vinyl monomer (a2) having 4 or more carbon atoms, and other copolymerizable vinyl monomers. (A3) is included (however, the sum of (a1) to (a3) is 100% by mass).

[Cyano group-containing vinyl monomer (a1)]
Examples of the cyano group-containing vinyl monomer (a1) (hereinafter sometimes referred to as monomer (a1)) include acrylonitrile and methacrylonitrile.

 Content of the monomer (a1) in a monomer mixture (A) is 3-30 mass%, and 10-20 mass% is more preferable. When the content of the monomer (a1) is not less than the above lower limit, the adhesion of the coating film to the ABS substrate is increased and the water resistance of the coating film is also increased. Moreover, if content of a monomer (a1) shall be below the said upper limit, the water resistance of a coating film will increase.

[Hydroxyl-containing vinyl monomer having 4 or more carbon atoms (a2)]
Examples of the hydroxyl group-containing vinyl monomer (a2) having 4 or more carbon atoms (hereinafter sometimes referred to as monomer (a2)) include 4-hydroxybutyl (meth) acrylate and 5-hydroxypentyl (meth). Acrylate, 6-hydroxyhexyl (meth) acrylate, 7-hydroxyheptyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 9-hydroxynonyl (meth) acrylate, allyl alcohol, methacryl alcohol, and lactones ( β-propiolaclone, dimethylpropiolactone, butyllactone, γ-valerolactone, ε-caprolactone, γ-caprolactone, γ-caprolactone, crotolactone, δ-valerolactone, δ-caprolactone, etc.) Etc., among others, adhesion and From the viewpoint of an aqueous, 4-hydroxybutyl (meth) acrylate. These can be used alone or in combination of two or more.

 Content of the monomer (a2) in a monomer mixture (A) is 1-10 mass%, and 1-5 mass% is more preferable. When the content of the monomer (a2) is at least the above lower limit, the adhesion of the coating film to the PP base material is increased. Moreover, if content of a monomer (a2) shall be below the said upper limit, the water resistance of a coating film will become high.

[Other copolymerizable vinyl monomers (a3)]
Other copolymerizable vinyl monomers (a3) (hereinafter sometimes referred to as monomer (a3)) are monomers (a1) except for monomer (a1) and monomer (a2). ) Or the monomer (a2), for example, an alkyl (meth) acrylate, an acid group-containing vinyl monomer, a maleimide derivative, an aldehyde group or a carbonyl group-containing vinyl monomer, Amide group-containing vinyl monomers, aromatic vinyl monomers, olefin monomers, monomers having two or more polymerizable unsaturated double bonds in the molecule (hereinafter referred to as polyfunctional monomers) Among them, alkyl (meth) acrylates and aromatic vinyl monomers are preferable from the viewpoint of further improving adhesion and water resistance.

 Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl ( Examples include meth) acrylate, n-lauryl (meth) acrylate, n-stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, and isobornyl (meth) acrylate. From the viewpoint of properties, methyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate are preferable.

 Examples of the acid group-containing vinyl monomer include (meth) acrylic acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, monobutyl maleate, monomethyl itaconate, monobutyl itaconate, vinyl benzoic acid, and oxalic acid. Monohydroxyethyl (meth) acrylate, monohydroxyethyl (meth) acrylate of tetrahydrophthalate, monohydroxypropyl (meth) acrylate of tetrahydrophthalate, monohydroxyethyl (meth) acrylate of 5-methyl-1,2-cyclohexanedicarboxylic acid, phthalate Acid monohydroxyethyl (meth) acrylate, monohydroxypropyl (meth) acrylate phthalate, monohydroxyethyl (meth) acrylate maleate, hydroxypropyl (meth) acrylate maleate , Tetrahydrophthalic acid mono-hydroxybutyl (meth) acrylate.

  Examples of maleimide derivatives include N-cyclohexylmaleimide and N-butylmaleimide.

Examples of the aldehyde group or carbonyl group-containing vinyl monomer include acrolein, diacetone acrylamide, formyl styrene, vinyl alkyl ketone, (meth) acrylamide pivalin aldehyde, diacetone (meth) acrylate, acetonyl acrylate, 2 -Hydroxypropyl acrylate acetyl acetate, acetoacetoxyethyl (meth) acrylate, butanediol-1,4-acrylate-acetyl acetate, acrylamide methyl anisaldehyde and the like.
Examples of the amide group-containing vinyl monomer include (meth) acrylamide, crotonamide, N-methylolacrylamide and the like.

 Examples of the aromatic vinyl monomer include epoxy group-containing vinyl monomers such as allyl glycidyl ether and glycidyl (meth) acrylate, styrene, and α-methylstyrene.

Examples of the olefin monomer include butadiene.
Examples of the polyfunctional monomer include divinylbenzene that undergoes an internal crosslinking reaction, diallylbenzene, diallyl maleate, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6- Hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, Examples include methylenebis (meth) acrylamide and triallyl cyanurate.

You may use these individually by 1 type or in combination of 2 or more types.
Moreover, content of the monomer (a3) in a monomer mixture (A) is 60-96 mass%. When the monomer (a3) is at least the above lower limit, the adhesion of the coating film to the substrate is increased and the water resistance of the coating film is increased. Moreover, if content of a monomer (a3) shall be below the said upper limit, the adhesiveness of the coating film to a base material will become high, and the water resistance of a coating film will also become high.

≪Monomer mixture (B) ≫
The monomer mixture (B) includes a cyano group-containing vinyl monomer (b1), a hydroxyl group-containing vinyl monomer (b2) having 4 or more carbon atoms, and an acid group-containing vinyl monomer (b3). ) And other copolymerizable vinyl monomers (b4) {provided that the sum of (b1) to (b4) is 100% by mass}.

[Cyano group-containing vinyl monomer (b1)]
Examples of the cyano group-containing vinyl monomer (b1) (hereinafter sometimes referred to as monomer (b1)) include those similar to monomer (a1).

 Content of the monomer (b1) in a monomer mixture (B) is 5-50 mass%, and 20-40 mass% is more preferable. When the content of the monomer (b1) is not less than the above lower limit value, the adhesion of the coating film to the ABS substrate is enhanced. When the content of the monomer (b1) is not more than the above upper limit value, the water resistance of the coating film is increased.

[Hydroxyl-containing vinyl monomer having 4 or more carbon atoms (b2)]
Examples of the hydroxyl group-containing vinyl monomer (b2) having 4 or more carbon atoms (hereinafter sometimes referred to as the monomer (b2)) include those similar to the monomer (a2). 4-hydroxybutyl (meth) acrylate is preferable from the viewpoint of water resistance and water resistance.

 Content of the monomer (b2) in a monomer mixture (B) is 1-30 mass%, and 5-20 mass% is preferable. When the content of the monomer (b2) is at least the above lower limit, the adhesion of the coating film to the PP base material is increased. When the content of the monomer (b2) is not more than the above upper limit value, the water resistance of the coating film is increased.

[Acid group-containing vinyl monomer (b3)]
Examples of the acid group-containing vinyl monomer (b3) (hereinafter sometimes referred to as monomer (b3)) include (meth) acrylic acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, and maleate. Monobutyl acid, monomethyl itaconate, monobutyl itaconate, vinylbenzoic acid, monohydroxyethyl (meth) acrylate oxalate, monohydroxyethyl (meth) acrylate tetrahydrophthalate, monohydroxypropyl (meth) acrylate tetrahydrophthalate, 5-methyl -1,2-cyclohexanedicarboxylic acid monohydroxyethyl (meth) acrylate, phthalate monohydroxyethyl (meth) acrylate, phthalate monohydroxypropyl (meth) acrylate, maleate monohydroxyethyl (meth) acrylate Maleic acid hydroxypropyl (meth) acrylate, tetrahydrophthalic acid mono-hydroxybutyl (meth) acrylate, and the like. Among these, from the viewpoint of improvement in adhesion and water resistance, (meth) acrylic acid are preferred. In addition, these can be used individually by 1 type or in combination of 2 or more types.

 Content of the monomer (b3) in a monomer mixture (B) is 1-30 mass%, and 10-20 mass% is preferable. When the content of the monomer (b3) is at least the above lower limit, the adhesion and water resistance of the coating film to the ABS base material and the PP base material are increased. When the content of the monomer (b3) is not more than the above upper limit value, the water resistance of the coating film is increased.

[Other copolymerizable vinyl monomers (b4)]
Other copolymerizable vinyl monomers (b4) are those that can be polymerized with at least one of the monomers (b1) to (b3) except for the monomers (b1) to (b3). For example, alkyl (meth) acrylates, maleimide derivatives, aldehyde or carbonyl group-containing vinyl monomers, amide group-containing vinyl monomers, aromatic vinyl monomers, olefin monomers, Examples thereof include functional monomers. Among these, alkyl (meth) acrylates and aromatic vinyl monomers are preferable from the viewpoints of adhesion and water resistance.

Examples of the alkyl (meth) acrylate include those similar to the alkyl (meth) acrylate exemplified as the monomer (a3).
Examples of the maleimide derivative include the same maleimide derivatives as the monomer (a3).
Examples of the aldehyde group- or carbonyl group-containing vinyl monomer include the same aldehyde group- or carbonyl group-containing vinyl monomers listed as the monomer (a3).
Examples of the amide group-containing vinyl monomer include the same amide group-containing vinyl monomers listed as the monomer (a3).
Examples of the aromatic vinyl monomer include the same aromatic vinyl monomers listed as the monomer (a3).
Examples of the olefin monomer include the same olefin monomers as the monomer (a3).
As a polyfunctional monomer, the same thing as the polyfunctional monomer quoted as a monomer (a3) is mentioned.
You may use these individually by 1 type or in combination of 2 or more types.

 Content of the monomer (b4) in a monomer mixture (B) is 1-93 mass%, and 1-65 mass% is preferable. When the content of the monomer (b4) is at least the above lower limit, the adhesion of the coating film to the substrate is increased and the water resistance of the coating film is also increased. By making content of a monomer (b4) below the said upper limit, the adhesiveness of the coating film to a base material becomes high, and the water resistance of a coating film also becomes high.

The weight average molecular weight (Mw) of the aqueous emulsion (I) is 80,000 or less, preferably 10,000 to 50,000. If the weight average molecular weight (Mw) of aqueous emulsion (I) is below the said upper limit, the adhesiveness of the coating film to a base material will increase. If the weight average molecular weight (Mw) of aqueous emulsion (I) is more than the said lower limit, water resistance will increase more.
A weight average molecular weight can be adjusted by using a chain transfer agent in the manufacturing method of aqueous emulsion (I) mentioned later.

 The weight average molecular weight of the aqueous emulsion (I) is a value measured using, for example, gel permeation chromatography (GPC) HLC-9120 (trade name, manufactured by Tosoh Corporation). First, a sample liquid is prepared by dispersing the aqueous emulsion (I) in tetrahydrofuran (THF) so as to be 0.4 mass%. About 100 microliters of this sample liquid, it measures at 40 degreeC using column: TSKgel G5000HXL * GMHXL-L (brand name, Tosoh Corporation make). From this measurement result and a calibration curve prepared in advance using TSK standard polystyrene (F288 / F80 / F40 / F10 / F4 / F1 / A5000 / A1000 / A500 (trade name, manufactured by Tosoh Corporation)) and styrene. The weight average molecular weight (Mw) of the aqueous emulsion (I) can be determined.

The volume average particle size of the aqueous emulsion (I) is preferably 20 to 500 nm, more preferably 30 to 300 nm, and further preferably 40 to 200 nm. When the volume average particle diameter is set to the above lower limit or more, the solid content of the paint at the time of coating increases and the workability is improved. When the volume average particle diameter is set to the upper limit or less, the appearance of the coating film is improved. Furthermore, if the volume average particle diameter is 200 nm or less, the film forming property of the coating film is improved.
The volume average particle diameter is a volume average particle diameter measured using a laser diffraction / scattering particle size distribution measuring apparatus.

From the viewpoint of the storage stability of the aqueous coating material, the aqueous emulsion (I) preferably has a constitutional unit derived from a polyfunctional monomer. Among them, diallyl maleate, ethylene glycol di (meth) acrylate, allyl It is more preferable to have a unit derived from (meth) acrylate, and it is more preferable to have a structural unit derived from diallyl maleate.
The content of the polyfunctional monomer in the total of the monomer mixture (A) and the monomer mixture (B) (hereinafter sometimes referred to as all monomers) is 0.1 to 5% by mass. Is preferable, and 1 to 5 mass% is more preferable. If the content of the polyfunctional monomer is not less than the above lower limit, the storage stability of the aqueous coating material is increased, and if it is not more than the above upper limit, the adhesion of the coating film to the substrate becomes higher, The water resistance of the coating film is also increased.

≪Method for producing aqueous emulsion (I) ≫
In the production method of the aqueous emulsion (I), the monomer mixture (A) is emulsion-polymerized to obtain an emulsion (hereinafter sometimes referred to as a primary emulsion) (first polymerization step), and a single amount in the primary emulsion. The body mixture (B) is subjected to emulsion polymerization (second polymerization step). That is, in the first polymerization step, the monomer mixture (A) is polymerized as the first stage polymerization reaction monomer, and in the second polymerization step, the monomer mixture (B) is polymerized in the second stage. An aqueous emulsion (I) having a multilayer structure is prepared by a multistage polymerization method in which polymerization is performed as a monomer. By having a specific amount of an acid group-containing vinyl monomer as the second-stage polymerization reaction monomer, compatibility with the chlorinated PP resin is improved, and adhesion with the PP base material is improved. . This water-based coating material can exhibit adhesion and water resistance to various substrates, which cannot be obtained with a single layer resin.

 Examples of the polymerization method in the first polymerization step include a known method in which the monomer mixture (A) is supplied into the polymerization reaction system in the presence of a surfactant and emulsion polymerization is performed using a radical polymerization initiator. For example, a primary emulsion can be prepared by mixing and stirring water, which is a dispersion medium, a monomer mixture (A), a radical polymerization agent, and a surfactant at an arbitrary temperature.

Examples of the radical polymerization initiator include those generally used for radical polymerization. For example, persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate, and oil solubility represented by azobisisobutyronitrile. Organic peroxides such as azo compounds, benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide and the like can be mentioned. These radical polymerization initiators can be used singly or in combination of two or more.
When acceleration of the polymerization rate and low temperature polymerization at 70 ° C. or lower are desired, for example, a reducing agent such as sodium bisulfite, Rongalite, ferrous sulfate, ascorbate is used in combination with the radical polymerization catalyst. And is advantageous.
The addition amount of the radical polymerization initiator is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of all monomers, and more preferably 0.05 to 5 parts by mass from the viewpoint of the progress and control of the polymerization reaction.

Examples of the surfactant include various anionic, cationic or nonionic surfactants or polymer emulsifiers. Moreover, the reactive emulsifier which has an ethylenically unsaturated bond in surfactant component may be sufficient. Especially, it is preferable to use a reactive emulsifier from a viewpoint of improving the water resistance of a coating film more.
The preferable addition amount of the surfactant is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of all monomers. If it is more than the said lower limit, the polymerization stability and storage stability of a primary emulsion will improve. If it is below the said upper limit, the mixing | blending stability at the time of forming a coating material and temporal stability can be maintained, without impairing water resistance.

A chain transfer agent can be used in the first polymerization step. By using the chain transfer agent, the weight average molecular weight of the aqueous emulsion (I) can be adjusted.
Examples of the chain transfer agent include known chain transfer agents such as n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan, and n-dodecyl mercaptan. Is preferred.
0.1-5 mass parts is preferable with respect to 100 mass parts of all monomers, and, as for the addition amount of a chain transfer agent, 0.1-3 mass parts is more preferable. If the addition amount of the chain transfer agent is not less than the above lower limit value, the adhesion of the coating film to the substrate becomes higher. Moreover, if the addition amount of a chain transfer agent shall be below the said upper limit, the water resistance of a coating film will become higher.

 Although the polymerization rate of the monomer mixture (A) in a 1st polymerization process is not specifically limited, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable.

 The reaction temperature in the first polymerization step can be determined in consideration of the polymerization rate of the monomer mixture (A) and the like, for example, 40 to 85 ° C.

 In the second polymerization step, the monomer mixture (B) is added to the primary emulsion obtained in the first polymerization step, and this is mixed and stirred at an arbitrary temperature to polymerize the monomer mixture (B). To obtain an aqueous emulsion (I).

  The amount of the monomer mixture (B) added to the primary emulsion can be determined in consideration of the amount of the monomer (A) used in the first polymerization step. For example, the monomer mixture (A) / single amount The mass ratio represented by the body mixture (B) (hereinafter sometimes referred to as (A) / (B) ratio) is preferably 50/50 to 95/5, more preferably 60/40 to 95/5, and further Preferably, it is set to 70/30 to 95/5. This is because the adhesiveness to the ABS base material becomes better if the above lower limit value or more, and the adhesiveness to the ABS base material and PP base material becomes better if the upper limit value or less.

 In the second polymerization step, a chain transfer agent may be further added as necessary. The total amount of the chain transfer agent and the chain transfer agent added in the first polymerization step is preferably 0.1 to 5 parts by mass, more preferably 0. The amount is 1 to 3 parts by mass.

 The reaction temperature in the second polymerization step can be determined in consideration of the types of the monomers (b1) to (b4) and is, for example, 40 to 85 ° C.

After polymerizing the monomer mixture (B), a basic compound may be added to the aqueous emulsion (I) to adjust the pH (pH adjusting operation).
The pH of the aqueous emulsion (I) is preferably pH 4 to 10 from the viewpoint of enhancing the stability of the emulsion, and more preferably pH 5 to 10 from the viewpoint of enhancing the freeze-thaw stability.

 Examples of the basic compound include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, sodium hydroxide, potassium hydroxide and the like. It is done.

<Chlorinated polyolefin resin (II)>
The chlorinated polyolefin resin (II) is not particularly limited. For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polybutene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer. A chlorinated polyolefin resin obtained by chlorinating modified polyolefins in which carboxyl groups, hydroxyl groups, acid anhydride groups, etc. are introduced into polyolefins such as polymers, styrene-isoprene copolymers, natural rubbers, and olefin rubbers by a known method. Etc.
The production method of the chlorinated polyolefin resin (II) is not particularly limited. For example, the polyolefin is dissolved or dispersed in an appropriate medium and then reacted with chlorine gas to easily obtain the desired chlorinated polyolefin resin. Can be obtained. As the medium, water is preferably used in consideration of the environment.
The chlorinated polyolefin resin (II) is preferably a chlorinated polyolefin resin obtained by chlorinating polypropylene and / or polyethylene, and an acid anhydride-modified chlorinated polyolefin obtained by modifying the chlorinated polyolefin resin with maleic anhydride or the like. Is more preferable.
Examples of commercially available products of chlorinated polyolefin resins include Supercron (trade name; manufactured by Nippon Paper Chemicals Co., Ltd.), Hardren (trade name; manufactured by Toyo Kasei Co., Ltd.), and the like.

 The chlorinated polyolefin resin (II) can be used in various forms such as a solid, a solution and a dispersion. The form of the chlorinated polyolefin resin (II) is not particularly limited, and for example, a chlorinated polyolefin resin in a solution form in which a solid is dissolved in a soluble medium, or a chlorinated polyolefin obtained by a method of dispersing in an aqueous medium An emulsion etc. are mentioned.

The chlorine content in the chlorinated polyolefin resin (II) is not particularly limited, but is preferably 10 to 40% by mass from the viewpoint of the storage stability of the aqueous coating material and the improvement in adhesion to difficult-to-paint plastic materials. 30 mass% is more preferable. If the chlorine content is not less than the above lower limit, the adhesion to difficult-to-paint plastic materials, the water resistance is further increased, and if not more than the above upper limit, the adhesion to difficult-to-paint plastic materials, Water resistance is further increased.
Although the weight average molecular weight of chlorinated polyolefin resin (II) is not specifically limited, 50,000-200,000 are preferable and 50,000-150,000 are more preferable. If a weight average molecular weight is more than the said lower limit, water resistance will increase more, if it is below the said upper limit, compatibility with aqueous emulsion (I) will increase and the adhesiveness of a coating film will increase more.

  As chlorinated polyolefin resin (II), Hardren EW-5303 (manufactured by Toyo Kasei Co., Ltd., active ingredient 30%, chlorine content 17% by mass), Supercron E-503 (manufactured by Nippon Paper Industries Co., Ltd., effective) Component 30%, chlorine content 20% by mass) and the like. These can be used alone or in combination of two or more.

<Method for producing aqueous coating material>
The manufacturing method of the aqueous coating material of this invention mixes aqueous emulsion (I) and chlorinated polyolefin resin (II) (mixing process).
The mixing method of water-based emulsion (I) and chlorinated polyolefin resin (II) is not specifically limited, The mixing method using a conventionally well-known mixing apparatus is mentioned.

  The compounding ratio of the aqueous emulsion (I) and the chlorinated polyolefin resin (II) is not particularly limited, and can be determined in consideration of the physical properties of the obtained aqueous coating material. The mass ratio represented by [solid content of aqueous emulsion (I)] / [solid content of chlorinated polyolefin resin (II)] (hereinafter sometimes referred to as (I) / (II) ratio) is, for example, 50 / 50 to 95/5 is preferable, and 60/40 to 80/20 is more preferable. This is because the adhesiveness to the ABS base material is better if it is above the lower limit value, and the adhesiveness to the PP base material is better if it is below the upper limit value.

(paint)
The paint of the present invention includes an aqueous coating material.
The content of the aqueous coating material in the paint is, for example, 10 to 80% by mass as the solid content of the aqueous coating material.
In paints, various pigments, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, matting agents, UV absorbers, antioxidants, and heat resistance improvers are used to develop advanced performance as coating materials. , Slip agents, preservatives, and the like may be included. Further, the paint may be used by mixing with other emulsion resins, water-soluble resins, viscosity control agents, melamines and other curing agents.

(Plastic molding)
The plastic molded product of the present invention is a product coated with the paint of the present invention.
The molded object (the object to be coated) to be painted may be made of a plastic base material for forming the surface to be painted (surface to be painted). For example, a polyolefin base material such as a polyethylene base material or a polypropylene base material , ABS base materials, styrene base materials and the like on which the surface to be coated is formed are mentioned. Among them, polypropylene base materials and ABS base materials on which the surface to be coated are formed are preferable.

 Examples of the method for applying a paint to a plastic substrate include conventionally known coating methods such as spray coating, roller coating, bar coating, brush coating, and dipping. Furthermore, the coating film which was excellent by adhesiveness, water resistance, oil resistance, and storage stability is obtained by heating at 50-90 degreeC for 5 to 30 minutes after the coating to a base material, for example.

 As described above, according to the aqueous coating material of the present invention, a coating film having good adhesion to a plastic substrate, particularly an ABS substrate and a polypropylene substrate, and excellent in water resistance can be obtained. .

  EXAMPLES Hereinafter, although an Example is shown and demonstrated about this invention, this invention is not limited to an Example. In the following description, “part” and “%” are based on mass unless otherwise specified.

The abbreviations in the table indicate the following compounds.
n-DM: n-dodecyl mercaptan 2-ME: 2-mercaptoethanol AN: acrylonitrile 4HBA: 4-hydroxybutyl acrylate 2-HEMA: 2-hydroxyethyl methacrylate MMA: methyl methacrylate i-BMA: isobutyl methacrylate MDAL: diallyl maleate MAA: Methacrylic acid AA: Acrylic acid E-503: Supercron E-503 (chlorinated polyolefin resin, active ingredient 30%, manufactured by Nippon Paper Industries Co., Ltd.)
EW-5303: Hardren EW-5303 (chlorinated polyolefin resin, active ingredient 30%, manufactured by Toyo Kasei Co., Ltd.)

(Evaluation method)
<Adhesion test>
The aqueous coating material of each example is 20 μm in dry thickness on a 3 mm thick plate formed from ABS resin “3001M” (Mitsubishi Rayon Co., Ltd.) or polypropylene resin “TX-1810A” (Nihon Polychem Co., Ltd.). The sample was spray-coated and dried in an atmosphere at 80 ° C. for 30 minutes to obtain a test piece on which a coating film was formed.
Next, on the coating surface of the test piece, 11 cuts were made in each of the vertical and horizontal directions at intervals of 1 mm so as to reach the substrate, and 100 grids were made. After applying the cellophane adhesive tape on the grid, the adhesive tape was peeled off rapidly. The state of the coating film after peeling off the adhesive tape was observed and evaluated according to the following evaluation criteria.
≪Evaluation criteria≫
(Double-circle): 100 squares of coating films remain in 100 squares.
◯: 95 to 99 coating films remain in 100 squares.
(Triangle | delta): 1-94 squares of coating films remain in 100 squares.
X: All the coating films in 100 squares are peeled off.

<Water resistance test>
After immersing the test piece prepared in “<Adhesion Test>” in warm water at 40 ° C. for 7 days, the coating surface of the test piece was cut into 11 cuts of 11 mm in length and width so as to reach the substrate. I made individual grids. After applying the cellophane adhesive tape on the grid, the adhesive tape was peeled off rapidly. The state of the coating film after peeling off the adhesive tape was observed and evaluated according to the following evaluation criteria.
≪Evaluation criteria≫
(Double-circle): 100 squares of coating films remain in 100 squares.
◯: 95 to 99 coating films remain in 100 squares.
Δ: 1 to 94 squares remain in 100 squares.
X: All the coating films in 100 squares are peeled off.

Example 1
A flask equipped with a stirrer, a reflux condenser, a temperature controller and a dropping pump was charged with 125 parts of deionized water and Adekaria soap SR-10 (1.25 parts) as a surfactant, and the temperature was raised to 80 ° C. Keep warm. Next, monomer (a1): acrylonitrile (17.5 parts), monomer (a2): 4-hydroxybutyl (meth) acrylate (2.75 parts) and monomer (a3): methyl methacrylate (54 .75 parts) and isobutyl methacrylate (22.5 parts) and diallyl maleate (2.5 parts) (monomer mixture (A)) and the chain transfer agent n-dodecyl mercaptan (1.2 Part). Furthermore, 50 parts of deionized water and Adekari Soap SR-10 (1.25 parts) were added to prepare a first pre-emulsion solution. 25 parts of this first pre-emulsion liquid was sampled and put into a flask, and then ammonium persulfate (0.75 part) as a radical polymerization initiator was added. After 30 minutes, the remaining first pre-emulsion liquid (127.75 parts) was added dropwise over 3 hours to obtain a primary emulsion (first polymerization step).
Monomer (b1): acrylonitrile (30 parts), monomer (b2): 4-hydroxybutyl (meth) acrylate (11 parts), monomer (b3): methacrylic acid (15 parts), Monomer (b4): Methyl methacrylate (16.5 parts) and isobutyl methacrylate (27.5 parts) were mixed to obtain a monomer mixture (B). This monomer mixture (B), n-dodecyl mercaptan (0.12 parts) as a chain transfer agent, 50 parts of deionized water, and Adecalia Soap SR-10 (1.25 parts) are mixed. A second pre-emulsion solution was prepared.
One hour after the completion of the first polymerization step, the second pre-emulsion was dropped into the primary emulsion over 1 hour. Thereafter, the mixture was cooled to room temperature, and 28% aqueous ammonia (1.85 parts) was added to obtain an aqueous emulsion (I) (pH: 6.0, solid content: 30%) (second polymerization step).

The obtained aqueous emulsion (I) and Super Clone E-503, which is a chlorinated polyolefin resin (II), were blended according to the ratio (I) / (II) shown in Table 1. 2-Dimethylaminoethanol was added to 100 g (solid content) of a mixture of the aqueous emulsion (I) and the chlorinated polyolefin resin (II) to adjust the pH to 8.0. Furthermore, 12 g of diethylene glycol monobutyl ether was added as a film forming aid, and then stirred with a disper to obtain an aqueous coating material (mixing step).
The obtained aqueous coating material was evaluated for adhesion and water resistance, and the results are shown in the table.

(Examples 2-14, Comparative Examples 1-13)
Tables 1-3 show the chain transfer agent and monomer mixture (A) in the first polymerization step, the chain transfer agent and monomer mixture (B) in the second polymerization step, and the ratio (I) / (II). The aqueous coating material of each example was obtained like Example 1 except having followed the composition shown in these.
The obtained aqueous coating material was evaluated for adhesion and water resistance, and the results are shown in the table.

(Comparative Example 14)
An aqueous coating material was obtained in the same manner as in Example 1 except that all the monomers were polymerized in the first polymerization step and the second polymerization step was not provided.
The obtained aqueous coating material was evaluated for adhesion and water resistance, and the results are shown in the table.

As shown in Tables 1 to 3, in Examples 1 to 14 to which the present invention was applied, both the adhesion to the ABS base material and the PP base material, and the water resistance in the ABS base material and the PP base material were “◯. Or “「 ”.
Comparative Example 1 using a monomer mixture (A) having a monomer (a1) content of 2% by mass, and a monomer mixture (B) having a monomer (b1) content of 2% by mass In Comparative Example 5 using No., the evaluation of adhesion (ABS) and water resistance (ABS) was “x”.
Comparative Example 2 using a monomer mixture (A) having a monomer (a1) content of 40% by mass, and a monomer mixture (B) having a monomer (b1) content of 60% by mass In Comparative Example 6 using No., the water resistance (ABS and PP) was evaluated as “x”.
In Comparative Example 3 in which the monomer (a2) was not used and in Comparative Example 7 in which the monomer (b2) was not used, the evaluation of adhesion (PP) and water resistance (PP) was “x”.
In Comparative Example 11 using the comparative product 2-HEMA instead of the monomers (a2) and (b2), the evaluation of adhesion (ABS and PP) and water resistance (ABS and PP) was “x”. .
Comparative Example 4 using a monomer mixture (A) having a monomer (a2) content of 15.25% by mass, and a monomer mixture having a monomer (b2) content of 50% by mass ( In Comparative Example 8 using B), the water resistance (ABS and PP) was evaluated as “x”.
Comparative Example 9 using the monomer mixture (B) having a monomer (b3) content of 0.5% by mass has an evaluation of adhesion (ABS and PP) and water resistance (ABS and PP). X ".
In Comparative Example 10 using the monomer mixture (B) having a monomer (b3) content of 50% by mass, the water resistance (ABS and PP) was evaluated as “x”.
In Comparative Example 12 using the aqueous emulsion (I) having a weight average molecular weight of 100,000, the evaluation of adhesion (ABS and PP) and water resistance (ABS and PP) was “x”.
In Comparative Example 14 in which all the monomers were polymerized in the first polymerization step to form an aqueous coating material having a single layer structure, the evaluation of adhesion (PP) and water resistance (PP) was “x”. .
From the above results, it was found that the water-based coating material to which the present invention was applied had good adhesion to both the ABS base material and the polypropylene base material, and a coating film excellent in water resistance was obtained. .

Claims (4)

Cyano group-containing vinyl monomer (a1) 3 to 30% by mass, hydroxyl group-containing vinyl monomer (a2) 1 to 10% by mass having 4 or more carbon atoms, and other copolymerizable vinyl monomers Monomer mixture (A) containing the body (a3) {however, the sum of (a1) to (a3) is 100% by mass} to an emulsion obtained by emulsion polymerization of a cyano group-containing vinyl monomer (B1) 5 to 50% by mass, 1 to 30% by mass of a hydroxyl group-containing vinyl monomer (b2) having 4 or more carbon atoms, and 1 to 30% by mass of an acid group-containing vinyl monomer (b3) And a monomer mixture (B) containing other copolymerizable vinyl monomer (b4) {provided that the total of (b1) to (b4) is 100% by mass}, and then obtained by emulsion polymerization. An aqueous emulsion (I) having a weight average molecular weight of 80000 or less,
A water-based coating material for plastic substrates, comprising chlorinated polyolefin resin (II).   The aqueous coating material for plastic substrates according to claim 1, wherein the mass ratio represented by the aqueous emulsion (I) / chlorinated polyolefin resin (II) is 50/50 to 95/5.   A paint comprising the aqueous coating material for a plastic substrate according to claim 1 or 2. A plastic molded article coated with the paint according to claim 3.