JPH09137124A - Coating resin composition and production of coating emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-base coating resin compsn. which forms a coating film excellent in resistances to water and staining, and a process for producing a coating emulsion excellent in production stability. SOLUTION: This water-base coating resin compsn. comprises an emulsion of a graft block copolymer which comprises polymer blocks comprising repeating dimethylsiloxane units, carbonylated polymer blocks comprising repeating vinyl monomer units, and silicon-contg. graft cross-linking units and an org. hydrazine compd. The emulsion is produced by subjecting a cyclic dimethylsiloxane oligomer and a graft cross-linking agent to emulsion polymn. in the presence of an acidic emulsifier, neutralizing the resultant product, and grafting onto the product a carbonylated polymerizable vinyl monomer in the presence of a free-radical-polymn. initiator.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous resin composition for paints and a method for producing an emulsion for paints used therefor. More specifically, it forms a coating film excellent in water resistance and stain resistance. The present invention relates to an aqueous resin composition for paints, and a method for producing an emulsion for paints excellent in production stability.

[0002]

2. Description of the Related Art Conventionally, solvent-based paints have been mainly used as paints. However, solvent-based paints may cause inflammation and poisoning and may cause environmental pollution. The transition to paint is progressing rapidly. However, water-based paints have lower coating film performances such as water resistance than solvent-based paints, and there are many problems to be solved under the present circumstances.

The improvement of coating performance of water-based paints has been extensively studied, and one of them is to have an emulsion of a resin containing a carbonyl group based on an aldehyde group or a keto group and two or more hydrazine residues. A resin composition comprising an organic hydrazine compound is disclosed in JP-A-54-144432. This resin composition has an excellent feature that a coating film can be formed at room temperature and can be used as a one-pack type, but has a drawback that the resulting coating film has insufficient water resistance, Contamination is not sufficient.

[0004]

On the other hand, various polysiloxane-based water-based paints have been developed as water-based paints. The polysiloxane resin used as a raw material of such a silicone-based water-based paint has excellent heat resistance, water repellency, and weather resistance, and has characteristics useful as a resin for a paint. However, there are still some problems in practical use of an aqueous paint containing a polysiloxane resin as a main component, and the present situation is that it has not yet been widely used for general paint applications.

For example, Japanese Examined Patent Publication (Kokoku) No. 63-23212 discloses a method for producing a water-soluble paint using a resin in which a plurality of alcoholic hydroxyl groups are introduced into a side chain of polysiloxane. However, a paint using a polysiloxane of the type that is completely soluble in water as described above requires a polysiloxane resin with a high molecular weight in order to improve coating properties, and in this case, the paint viscosity increases, It has the drawback that its coatability is reduced. Furthermore, the coating film formed from this coating material has a large amount of hydrophilic functional groups, and therefore has the drawback that the coating film has low water repellency and water resistance.

An object of the present invention is to provide a resin composition for paints, which forms a coating film excellent in water resistance and stain resistance, and a method for producing an emulsion for paints excellent in production stability.

[0007]

SUMMARY OF THE INVENTION The inventors of the present invention have achieved the present invention as a result of earnestly examining an aqueous resin composition for coating in view of the above-mentioned problems of the prior art.

That is, the gist of the present invention is to
A polymer block (A) having dimethylsiloxane as a repeating unit, a polymer block (B) having a vinyl-polymerizable monomer as a repeating unit and containing at least one carbonyl group based on an aldehyde group or a keto group, and the polymer block (A). An emulsion of a graft block copolymer (I) comprising a polymer block (A) and a silicon-containing graft crossing unit (C) copolymerized with the polymer block (B), and two or more hydrazine residues Organic hydrazine compound (II)
And a resin composition for coating material.

[0009] Furthermore, another point is that
A cyclic dimethyl siloxane oligomer and a graft-linking agent consisting of a polyfunctional alkoxysilane containing a vinyl-polymerizable functional group and / or a mercapto group are emulsion-polymerized in the presence of an acidic emulsifier and neutralized to form an aldehyde group or keto group. Vinyl polymerizable monomer containing a carbonyl group based on
And another vinyl-polymerizable monomer, which is graft-copolymerized in the presence of a radical polymerization initiator.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition for coating of the present invention (hereinafter referred to as a resin composition) is an emulsion obtained by emulsifying and dispersing a graft block copolymer (I) in an aqueous medium in which a surfactant is present. Further, the organic hydrazine compound (II) having two or more hydrazine residues is contained therein.

The graft block copolymer (I) constituting the resin composition of the present invention comprises a polymer block (A) containing dimethylsiloxane as a repeating unit (hereinafter referred to as polymer block (A)), vinyl polymerizability. A polymer block (B) containing a monomer as a repeating unit and containing at least one carbonyl group based on an aldehyde group or a keto group (hereinafter referred to as polymer block (B)) and a silicon-containing graft crossing unit (C) ( Hereinafter referred to as graft crossover unit (C))
The graft crossing unit (C) is copolymerized with both the polymer block (A) and the polymer block (B) through one or more siloxane bonds.

The copolymerization of the graft crossing unit (C) and the polymer block (B) is carried out by polymerizing the vinyl polymerizable functional group and / or mercapto group in the graft crossing agent which is a raw material of the graft crossing unit (C) with the polymer. It can be achieved by radical copolymerization with a vinyl polymerizable monomer that is a raw material of the block (B).

Graft block copolymer (I) of the present invention
Is a dimethyldialkoxysilane such as dimethyldimethoxysilane and dimethyldiethoxysilane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexa. Siloxane, tetradecamethylcycloheptasiloxane,
It can be synthesized using dimethylsiloxane cyclic oligomers such as dimethylcyclics (a mixture of dimethylsiloxane cyclic oligomers 3 to 7-mer), dimethyldichlorosilane and the like as raw materials. Considering performance such as raw material price and heat stability of the obtained resin, polymer block (A)
Most preferred as a raw material for the dimethyl siloxane cyclic oligomer.

Graft block copolymer (I) of the present invention
The polymer block (B) constituting the above is characterized in that it contains at least one carbonyl group based on an aldehyde group or a keto group. This functional group can be introduced into the polymer block (B) by using a vinyl polymerizable monomer having a carbonyl group based on an aldehyde group or a keto group.

The carbonyl group based on the aldehyde group or keto group contained in the polymer block (B) does not include a carboxyl group, an ester group and an amide group. Examples of the vinyl polymerizable monomer having a carbonyl group based on an aldehyde group or a keto group used as a constituent component of the polymer block (B) include, for example, acrolein, diacetone acrylamide, formyl styrene, vinyl methyl ketone, vinyl. Vinyl alkyl ketones having 4 to 7 carbon atoms such as ethyl ketone and vinyl isobutyl ketone, diacetone acrylate, diacetone methacrylate
, Acetonyl acrylate, acryloxyalkylpropenal, methacryloxyalkylpropenal, etc., but diacetone acrylamide, acrolein, vinyl methyl ketone are preferable in view of polymerization reactivity, crosslinking reactivity, cost and the like. . These components can be used alone or in combination of two or more as necessary.

The content of the vinyl polymerizable monomer having a carbonyl group based on an aldehyde group or a keto group is preferably in the range of 1 to 30% by weight in the polymer block (B). This is because the content of vinyl polymerizable monomer is 1% by weight.
If it is less than 30% by weight, water resistance and solvent resistance of the resulting coating film tend to be deteriorated, which is not preferable, and if it exceeds 30% by weight, the effect of improving coating film performance cannot be obtained any more, and conversely it is obtained. The water resistance of the coating film tends to decrease, which is not preferable.
More preferably, it is in the range of 1 to 10% by weight. Within this range, the water resistance and solvent resistance of the coating film are particularly good.

Other vinyl polymerizable monomers used for constituting the polymer block (B) include, for example,
Methacrylates such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, n-lauryl methacrylate, n-stearyl methacrylate, cyclohexyl methacrylate and the like. Acid alkyl ester, methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, acrylic acid t
-Butyl, 2-ethylhexyl acrylate, n-lauryl acrylate, n-stearyl acrylate, alkyl acrylates such as cyclohexyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxy methacrylate. Methacrylic acid hydroxyalkyl ester such as hexyl, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxyalkyl acrylate such as 6-hydroxyhexyl acrylate, aromatic vinyl unit such as styrene and α-methylstyrene Body, methacrylamide,
Amide group-containing vinyl monomers such as acrylamide, crotonamide, N-methylolacrylamide, methacrylic acid, acrylic acid, crotonic acid, fumaric acid, maleic acid,
Examples include carboxyl group-containing vinyl monomers such as itaconic acid and sorbic acid, and nitrile group-containing vinyl monomers such as acrylonitrile. These components can be used alone or in combination of two or more as necessary.

The polymer block (B) is preferably contained in the graft block copolymer (I) in an amount of 50 to 98% by weight. When the content of the polymer block (B) is 5
When it is less than 0% by weight, the hardness and strength of the coating film formed from the resin composition tend to be lowered, which is not preferable, and when the content of the polymer block (A) exceeds 98% by weight. However, the stain resistance and flexibility of the coating film tend to decrease, which is not preferable. More preferably, it is in the range of 70 to 95% by weight.

The graft block copolymer (I) of the present invention
Is a constituent unit necessary for ensuring the transparency of the resulting coating film, and contains the graft-crossing unit (C) in the graft block copolymer (I) of the present invention. The amount is preferably in the range of 1 to 50 mol%, based on the silicon atoms in the graft block copolymer (I) of the present invention. This is because when the content of the graft crossing unit (C) is less than 1 mol%, the transparency of the obtained resin coating film tends to decrease, and when it exceeds 50 mol%, it becomes disadvantageous in terms of raw material cost. In addition, by-products such as alcohol that are eliminated during condensation tend to deteriorate the emulsion stability and handleability, and further the coating film performance, which is not preferable. More preferably 1.5 to 15
Mol% range. When the content is 1.5 mol% or more, the transparency of the coating film obtained is extremely good, and when the content is 15 mol% or less, the latex stability during emulsion polymerization is good. .

The graft crossing agent constituting the graft crossing unit (C) of the present invention contains at least one hydrolyzable silyl group and at least one vinyl polymerizable functional group or mercapto group in the molecule. A compound can be mentioned.
As the hydrolyzable silyl group, an alkoxysilyl group is preferable in consideration of polymerization reactivity, ease of handling, cost, and the like. Specific examples of the graft crossing agent include vinylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane and other vinylsilanes, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxy. Methacryloxyalkylsilanes such as propyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, acryloxyalkylsilanes such as 3-acryloxypropyltriethoxysilane, 3-mercaptopropyl Mercaptoa such as trimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropylmethyldiethoxysilane. Although Kirushiran ethers. Among them, vinyl-polymerizable, consider a methacryloxy alkyl silanes such as cost and acryloxy alkylsilanes and mercaptoalkyl silanes are particularly preferred. These components can be used alone or in combination of two or more as necessary.

The resin composition of the present invention further comprises two or more hydrazine residues in an emulsion obtained by emulsifying and dispersing the graft block copolymer (I) in an aqueous medium in which a surfactant is present. Having an organic hydrazine compound (I
By containing I), it can be used as a coating emulsion.

The organic hydrazine compound (II) used in the present invention is the same as the number of moles (i) of the carbonyl group based on the aldehyde group or keto group in the graft block copolymer (I) and the organic hydrazine compound (II). The ratio of the number of moles of hydrazine residues (ii) is 0.05 ≦ (ii) /
It is preferable to add (i) so that the range is ≦ 5.

If (ii) / (i) is less than 0.05, the progress of the crosslinking reaction tends to be inadequate, and the water resistance and solvent resistance of the coating film formed tend to be inadequate. When it exceeds 5, the residual unreacted organic hydrazine compound tends to adversely affect the appearance and water resistance of the coating film. More preferably, the range is 0.5 ≦ (ii) / (i) ≦ 2. Within this range, the appearance, water resistance and solvent resistance of the coating film will be extremely good.

Specific examples of the organic hydrazine compound (II) include dicarboxylic acid dihydrazides containing 2 to 10, especially 4 to 6 carbon atoms, for example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide and glutar. Acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide and itaconic acid dihydrazide, and aliphatic water-soluble dihydrazine having 2 to 4 carbon atoms, for example, ethylene-1,2-di Hydrazine,
Propylene-1,3-dihydrazine, butylene-1,4
-Dihydrazine and the like can be mentioned. Of these, adipic dihydrazide, isophthalic dihydrazide, sebacic dihydrazide and succinic dihydrazide are preferred. These may be used in combination of two or more.

In the resin composition of the present invention, the graft block copolymer (I) exists as emulsion particles. This emulsion particle size can be arbitrarily changed by selecting the production conditions, but the usual average particle size is 0.01 to
It is about 1.0 μm.

The content of the resin component in the resin composition of the present invention can be arbitrarily selected, but a content of 30 to 60% by weight is preferable in consideration of coating workability and coating performance.

The resin composition of the present invention can be obtained by adding the organic hydrazine compound (II) having two or more hydrazine residues to the emulsion of the graft block copolymer (I).

A production method by which an emulsion of the graft block copolymer (I) can be suitably produced will be explained below, but the production method is not particularly limited.

The method for producing a graft block copolymer emulsion of the present invention comprises a cyclic dimethylsiloxane oligomer and a graft crossing agent comprising a polyfunctional alkoxysilane having a vinyl polymerizable functional group and / or a mercapto group, in the presence of an acidic emulsifier. After emulsion polymerization and neutralization,
It can be suitably produced by graft-copolymerizing a vinyl-polymerizable monomer having a hydrolyzable silyl group and another vinyl-polymerizable monomer in the presence of a radical polymerization initiator.

The ratio between the total amount of the cyclic dimethylsiloxane oligomer and the graft crossing agent and water can be arbitrarily selected, but the weight ratio is preferably in the range of 1: 1 to 1: 9.

The acidic emulsifier is not particularly limited as long as it can open the cyclic dimethylsiloxane oligomer, but an example of the acidic emulsifier suitable for polymerization is dodecylbenzenesulfonic acid. The preferable amount of the acidic emulsifier used varies depending on the particle size of the intended emulsion, the solid content, the polymerization temperature and the combined use of other surfactants, but in order to accelerate the polymerization of the siloxane, the cyclic dimethylsiloxane oligomer and It is preferable to use 0.5% by weight or more based on the total amount of the graft crossing agent.

The emulsion polymerization temperature of the cyclic dimethylsiloxane oligomer and the graft crossing agent is not particularly limited, but in order to increase the reaction rate and accelerate the polymerization more quickly,
It is preferable to receive a heat history of at least 60 ° C. at least once, more preferably at least 75 ° C.

The particle size of the obtained siloxane polymer emulsion can be controlled by the degree of preliminary dispersion of the raw material, the amount of emulsifier, the polymerization temperature and the method of supplying the raw material. Emulsions having a smaller particle size are prepared by preliminarily emulsifying the raw material and water with a high shear generator such as a homogenizer in the presence of an emulsifier, dropping the raw material or pre-emulsion into water, increasing the emulsifier, or polymerizing. It can be obtained by any method of raising the temperature or by appropriately combining these methods.

Since the obtained siloxane polymer emulsion is strongly acidic, it is necessary to neutralize it after the siloxane polymerization is completed. The basic compound used for neutralization is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, ammonia, and triethylamine. Neutralization is performed by adding these basic compounds directly or in an aqueous solution to the emulsion.

When the vinyl-polymerizable monomer contains an acid component such as methacrylic acid, the storage stability of the emulsion can be enhanced by neutralizing after the polymerization.

Known radical polymerization initiators are used in the subsequent graft copolymerization of vinyl-polymerizable monomers containing a carbonyl group based on an aldehyde group or a keto group and other vinyl-polymerizable monomers. Is available. Specifically, azo compounds such as azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), inorganic peroxides such as ammonium persulfate, potassium persulfate and sodium persulfate, and peroxides. Organic peroxides such as benzoyl oxide, t-butyl hydroperoxide, di-t-butyl peroxide, cumene hydroperoxide,
A redox-based catalyst represented by a combination of potassium persulfate or ammonium persulfate and sodium bisulfite or rongalite, a combination of an organic peroxide such as t-butylhydroperoxide or cumene hydroperoxide and sodium bisulfate or rongalite, etc. Can be mentioned.

The addition amount of the radical polymerization initiator is usually in the range of 0.01 to 10% by weight based on the total amount of the vinyl-polymerizable monomer, but when the progress of the polymerization and the control of the reaction are taken into consideration, The range of 0.1 to 5% by weight is preferable. Further, a compound containing a divalent iron ion such as iron sulfate and a chelating agent such as disodium ethylenediaminetetraacetate can be used to impart the activity of the polymerization initiator.

The method of charging the vinyl-polymerizable monomer is not particularly limited, and may be any method such as batch charging, dropping, or preliminarily charging a part and dropping the rest. When dropping, it may be dropped as it is, or may be dropped after pre-emulsification in the presence of an emulsifier. Also,
An emulsifier may be additionally added at the time of graft copolymerization of the vinyl polymerizable monomer or at the end of the graft copolymerization. The polymerization temperature is not particularly limited, but is usually in the range of 40 to 90 ° C.

Known emulsifiers can be used for pre-emulsification or additional addition. Specific examples include anionic emulsifiers such as sodium dodecylbenzene sulfonate, sodium lauryl sulfonate and sodium lauryl sulfate, and polyoxyethylene groups. Examples thereof include anionic emulsifiers, nonionic emulsifiers such as polyoxyethylene nonylphenyl ether and polyoxyethylene lauryl ether, and reactive emulsifiers having a vinyl polymerizable double bond in the molecule.

If necessary, a cosolvent may be added to the resin composition of the present invention in order to improve the film-forming property. Specific examples include methanol, ethanol, 2-propanol, ethylene glycol, propylene glycol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol. Examples include mono-n-butyl ether.

The resin composition of the present invention may optionally contain various additives such as pigments, ultraviolet absorbers, antioxidants, heat resistance improvers, leveling agents, anti-sagging agents and matting agents. Well, other emulsion resins, water-soluble resins,
It may be used by mixing with a viscosity controlling agent and a curing agent such as melamines.

The resin composition of the present invention can be applied by a method such as brush coating, roll coating or spray coating, and can be cured by leaving it at room temperature or by heating it at 50 to 200 ° C.

[0043]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” are “parts by weight” and “%”.
Indicates "% by weight".

Further, the evaluation of the performance in the examples and comparative examples was carried out by the following method.

(1) Hardness Mitsubishi Pencil Uni was used (hardness was measured by scratching the coating at an angle of 45 degrees) (2) Water resistance After being immersed in warm water of 40 ° C. for 3 days, the appearance of the coating was visually judged. None x: Decrease in gloss and significant whitening (3) Contamination resistance A red oil-based ink (Magic ink, registered trademark) was applied to the coating film, dried at room temperature for 1 hour, and wiped with 1-butanol to decolorize the ink. Is visually judged. ○: Almost no trace is left. Δ: A trace is left. ×: No decolorization is possible. [Production Example 1] Dimethyl cyclics (hereinafter DMC, mixture of cyclic dimethylsiloxane oligomer 3 to 7 mer) 8
5 parts, 3-methacryloyloxypropyltrimethoxysilane (hereinafter KBM-503) (graft crossing agent) 15
Part, 300 parts of water and 0.7 part of sodium dodecylbenzenesulfonate (hereinafter DBSNa) (surfactant) are premixed with a homomixer and then sheared by a homogenizer at a pressure of 350 kg / cm ² and forced. This was emulsified to obtain a silicone raw material emulsion.

Next, 100 parts of water and 5 parts of dodecylbenzenesulfonic acid (DBSA) (acidic emulsifier) were charged into a flask equipped with a stirrer, a condenser, a temperature controller and a dropping pump, and the temperature inside the flask was kept at 85 ° C. Meanwhile, the above silicone raw material emulsion was added dropwise over 3 hours. After completion of the dropwise addition, heating and stirring were further continued for 1 hour, the obtained emulsion was cooled to room temperature, and dodecylbenzenesulfonic acid was neutralized with sodium hydroxide to obtain a silicone emulsion (hereinafter referred to as SEm-1). The solid content of the obtained emulsion was 18%.

[0047]

Example 1 SEm-1 (62 parts), water (75 parts) and potassium persulfate (0.6 parts) were placed in a flask equipped with a stirrer, a condenser, a temperature controller, a dropping pump and a nitrogen introducing tube, and the temperature was raised to 70 ° C. After warming, diacetone acrylamide (hereinafter DAAm) while stirring under nitrogen atmosphere
A mixture of 3 parts, 35 parts of methyl methacrylate (hereinafter MMA), 35 parts of n-butyl methacrylate (hereinafter BMA), 25 parts of 2-ethylhexyl acrylate (hereinafter EHA) and 2 parts of methacrylic acid (hereinafter MAA) for 4 hours. It was dropped and polymerized. After completion of the dropping, the temperature was maintained at 70 ° C. for 1 hour, further raised to 80 ° C. and maintained for 1 hour. The reaction solution was cooled to room temperature and neutralized with aqueous ammonia to obtain a graft block copolymer emulsion. The polymerization proceeded stably, and no formation of aggregates was observed. The solid content of the obtained emulsion was 46%. To the obtained emulsion, 20 parts of propylene glycol monomethyl ether (hereinafter PGM) and 1.8 parts of adipic acid dihydrazide (hereinafter ADH) were added to 100 parts of resin solid content, respectively, and after mixing well, A bar coater No. 40 was applied to this on a water-coated plate for electrocoating, dried at room temperature for 30 minutes, and then heated at 70 ° C. for 1 hour to prepare a test coating film. Table 2 shows the evaluation results of the test coating films.

[0048]

Examples 2 to 4 and Comparative Example 1 Graft block copolymer emulsions were obtained in the same manner as in Example 1 except that the composition was changed to the composition shown in Table 1. All the polymerizations proceeded stably. Further, Table 2 shows the evaluation results of the test coating film prepared by adding and mixing PGM and ADH so as to have the composition shown in Table 2.

[0049]

[Table 1]

[0050]

[Table 2]

1) Ratio (parts) to 100 parts of solid content (Note) The value in parentheses is the value obtained by dividing the number of moles of hydrazine residue by the number of moles of carbonyl group based on aldehyde group or keto group.

[0052]

EFFECT OF THE INVENTION The resin composition for coatings of the present invention has water resistance,
It provides a coating film having excellent stain resistance and can be used for various coating applications as a resin for aqueous emulsion coatings, and is industrially very useful. Further, the method for producing a coating emulsion of the present invention is excellent in production stability and is very useful industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location // C08G 77/442 NUK C08G 77/442 NUK (72) Inventor Atsushi Nagamine Miyuki Town, Otake City, Hiroshima Prefecture No. 20-1 Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A polymer block (A) having dimethyl siloxane as a repeating unit, a polymer block having a vinyl polymerizable monomer as a repeating unit and containing at least one carbonyl group based on an aldehyde group or a keto group (B). ), And an emulsion of a graft block copolymer (I) composed of the polymer block (A) and a silicon-containing graft crossing unit (C) copolymerized with the polymer block (A),
And a resin composition for paints, which comprises an organic hydrazine compound (II) having two or more hydrazine residues. 2. A graft crossing agent comprising a cyclic dimethylsiloxane oligomer and a polyfunctional alkoxysilane containing a vinyl-polymerizable functional group and / or a mercapto group is emulsion-polymerized in the presence of an acidic emulsifier and neutralized, and then an aldehyde is formed. Vinyl polymerizable monomer containing a carbonyl group based on a group or a keto group, and other vinyl polymerizable monomer, characterized in that graft copolymerization in the presence of a radical polymerization initiator, coating emulsion Production method.