JP3287605B2 - Aqueous coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an aqueous coating composition, and more particularly, to an aqueous dispersion type coating composition such as a mastic paint, a soundproof paint, a vibration-proof paint, a caulking material, and more particularly,
It is used for protecting the sheet metal processing member from so-called "chipping", which is abrasion caused by a stepping stone of an outdoor sheet metal processing member such as a floor of a vehicle, especially an automobile floor, a tire house, a chassis, a gas tank, a suspension, etc. Excellent chipping properties, adhesion to metal workpieces, uniformity and smoothness of the coating, water resistance, gasoline resistance, impact resistance, soundproofing, etc., and at -30 ° C or below The present invention relates to a chipping-resistant aqueous coating composition based on synthetic rubber-based emulsion polymer particles, which also has excellent low-temperature properties such as chipping resistance.

[0002] Conventionally, as an aqueous chipping-resistant coating material used for an outdoor sheet metal processing member of vehicles such as automobiles, an aqueous resin dispersion such as a rubber-based latex or an acrylic copolymer emulsion has been used as a vehicle, and calcium carbonate has been used. And those containing an inorganic filler such as talc are known. For example, those based on an acrylic copolymer aqueous resin dispersion are disclosed in, for example, JP-A-53-64287.
JP, JP-A-59-75954, JP-A-62
230868, JP-A-63-10678,
It is disclosed in JP-A-63-172777 and the like.

However, the aqueous coating compositions for chipping resistance described in these publications have chipping resistance at room temperature (hereinafter, also referred to as "normal chipping resistance") and chipping resistance immediately after wetting with water ( Hereinafter, it may be referred to as “wet chipping resistance”), excellent adhesion to sheet metal processing members, impact resistance, particularly, for example, −
Various properties as a chipping-resistant coating agent such as impact resistance at cryogenic temperatures of 30 ° C. or less (hereinafter sometimes referred to as “low-temperature impact resistance”), and drying when forming a thick film such as 600 μm or more. It is not easy to satisfy both the anti-swelling properties in the process, and in order to improve the normal chipping resistance and the low-temperature impact resistance, if the amount of the inorganic filler in the coating material is reduced, the blisters in the baking process are reduced.
r) tends to occur, and when the amount of the filler is increased to prevent blistering, there is a problem that the normal-state chipping resistance and the low-temperature impact resistance are significantly reduced.

In recent years, in the production of automobiles and the like, in order to enhance the rust prevention properties, for example, a method of assembling a body, chassis, etc., and then performing cationic electrodeposition coating on the whole by "doping" is often adopted. However, when such a sheet metal processed member subjected to cationic electrodeposition coating is coated with the coating agent for chipping resistance described in the above publication, the adhesiveness of the coating agent tends to be insufficient, and the wet chipping resistance is significantly reduced. There is a tendency.

On the other hand, an aqueous coating agent for chipping resistance using a rubber-based latex as a vehicle is disclosed in, for example,
These are disclosed in JP-A-7-180617, JP-A-59-75954, JP-A-59-129213, and the like.

However, the aqueous coating composition for chipping resistance using a latex described in these publications has a problem that it is not always satisfactory in all of normal and wet chipping resistance and low-temperature impact resistance.

[0007] Further, an aqueous coating agent for chipping resistance using a rubber-based latex mixed with another copolymer as a vehicle is also known, for example, as disclosed in JP-A-54-521.
No. 39 proposes to use, as a vehicle, styrene-butadiene copolymer resin, a specific amount of each of vinyl chloride-vinyl acetate-unsaturated dibasic acid copolymer resin and low molecular weight liquid polymer. I have.

However, in the above publication,
Powdered vinyl chloride-vinyl acetate-unsaturated dibasic acid copolymer resin is usually used in powder form, but the copolymer resin powder is not easily dispersed, and the resulting coating is applied to a sheet metal processing member. It was found that the adhesiveness was insufficient and the chipping resistance was also insufficient.

Further, for example, in Japanese Patent Application Laid-Open No. 2-28269, as a base resin (vehicle component) in an aqueous coating agent for chipping resistance, a glass transition temperature formed by emulsion polymerization of styrene, butadiene and an acrylic monomer is used. It has been proposed to use a copolymer having a butadiene content of 5 to 50 parts by weight per 100 parts by weight of the copolymer at 0 ° C. or lower.

However, according to the examples of the above publication, the base resin is prepared by emulsion polymerization of an acrylic monomer in the presence of a styrene-butadiene rubber latex. When an attempt was made to prepare a copolymer according to the method described in the examples, the styrene-butadiene rubber latex was subjected to emulsion polymerization of an acrylic monomer in the presence of a residual double bond derived from a butadiene unit in the rubber latex. As a result, a copolymer having desired rubber elasticity could not be obtained, and only a hard and brittle copolymer could be obtained.

Further, the coating of the chipping-resistant coating agent on parts other than the body, such as shears, gasoline tanks, suspensions, etc., of the automobile parts is generally performed on a line different from the body coating line. For the purpose of reducing automobile manufacturing costs, attempts have been made to reduce the coating film baking temperature of the coating line to a relatively low temperature, for example, 100 ° C. or less. In this case, it is said that the problem of blistering can be almost avoided. Despite the advantages, it has also been found that there is the problem that the adhesion of the coating to these components is further reduced.

The present inventors have developed a coating for chipping resistance such as normal and wet chipping resistance, low-temperature impact resistance, adhesion to a substrate surface, uniformity and smoothness of a coating film, water resistance and solvent resistance. It has various properties as a material in a well-balanced manner.Moreover, even when forming a thick coating on a sheet metal processing member such as a car body that performs high-temperature baking, chipping resistance does not cause inconvenience such as blisters in the baking process. Intensive research was conducted for the purpose of providing a water-soluble coating composition.

A chipping-resistant aqueous coating composition mainly used for coating sheet metal working members such as parts other than the automobile body, wherein the coating film baking temperature is relatively low, for example, 100 ° C. or less. Even when it is used, it does not impair the adhesion of the coating film to the substrate surface, which tends to decrease, and also has a well-balanced chipping-resistant water-based coating which has the above other properties as a chipping-resistant coating agent. Further studies were conducted with the aim of providing a composition for use.

As a result, as a vehicle component of the aqueous coating composition, a synthetic rubber emulsion polymer having a glass transition temperature (hereinafter sometimes referred to as Tg) of 0 ° C. or lower;
It has been found that the above object can be achieved by using in combination with a specific emulsion polymer having a relatively high Tg of 20 ° C. or higher (hereinafter, sometimes referred to as a high Tg emulsion polymer). The present invention has been completed.
When a urethane emulsion polymer is used in combination as the vehicle component in addition to the above two emulsion polymers, the wet coating chipping resistance of the aqueous coating composition, the sheet metal processing member (base material), In particular, it has been found that the adhesion to a base material such as a cationic electrodeposition coated steel sheet is further improved.

Thus, one aspect of the present invention (aspect)
According to t), there is provided an aqueous coating composition comprising polymer fine particles dispersed in an aqueous medium and an inorganic filler, wherein the polymer fine particles contain (A) 30 to 90% by weight of a conjugated diolein unit. 50 to 95% by weight of synthetic rubber-based emulsion polymer particles having a glass transition temperature of 0 ° C. or less;

[0016]

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In the formula, R ¹ represents a hydrogen atom or a methyl group, and Q represents —COOR ² ,

[0018]

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Or --CN, wherein R ² represents a lower alkyl group, R ³ represents a hydrogen atom or a lower alkyl group, and has a glass transition temperature of 30 to 99.9% by weight. There is provided an aqueous coating composition comprising 5 to 50% by weight of emulsion polymer particles at at least 20 ° C.

According to another aspect of the present invention, the polymer fine particles may further comprise (C) a urethane emulsion polymer particle in addition to the emulsion polymer particles (A) and (B). The above aqueous coating composition is provided which contains 3 to 100% by weight based on the total amount of the polymer particles (A) and (B).

In the present specification, the expression "emulsion polymer particles" refers to fine particles of a polymer dispersed in an aqueous medium and has an average particle diameter of usually 1 micron or less, preferably 0.1 micron or less. It refers to dispersed particles of about 0.5 to 0.5 microns, and does not necessarily mean only polymer particles obtained by emulsion polymerization. In particular, the urethane emulsion polymer particles (C) can be produced without using emulsion polymerization as described later.

Hereinafter, the aqueous coating composition of the present invention will be described in more detail.

Synthetic Rubber Emulsion Polymer Particles (A) The synthetic rubber emulsion polymer particles (A) , which are one component of the vehicle in the aqueous coating composition of the present invention, contain a conjugated diolefine unit and a synthetic rubber polymer. Of rubber elasticity containing 30 to 90% by weight, preferably 40 to 80% by weight, and more preferably 45 to 75% by weight based on the weight of the rubber.

Such a synthetic rubber-based copolymer can be prepared, for example, by subjecting (a-1) a conjugated diolefin-based monomer to (a- 2) Aromatic vinyl monomer and / or vinyl cyanide monomer, preferably (a-3) carboxyl group-containing ethylenic monomer and further if necessary (a-4) other copolymerizable It can be formed by aqueous emulsion polymerization under pressure together with various monomers.

The above conjugated diolefin monomer (a-1)
Examples thereof include one or more monomers selected from butadiene, isoprene, chloroprene, and the like, and butadiene is particularly preferred. Examples of the aromatic vinyl monomer (a-2) include styrene, α-methylstyrene, vinyltoluene, and ethylvinylbenzene. Examples of the vinyl cyanide monomer (a-2) include: For example, acrylonitrile, methacrylonitrile and the like can be exemplified. These aromatic vinyl monomers and / or vinyl cyanide monomers (a-2) can be used alone or in combination of two or more. Particularly, styrene and / or acrylonitrile are preferred.

Further, the carboxyl group-containing ethylenic monomer (a-3) used in a suitable case contains a carboxyl group, which may be in a free form or a salt or an anhydride form, in one or two per molecule. Α, β-ethylenically unsaturated monomers, for example, C _3-5 α, β-unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid; citraconic acid, itaconic acid, maleic acid acid,
C _4-5 α, β-unsaturated dicarboxylic acids such as fumaric acid or anhydrides or C _1-12 monoalkyl esters (eg, monoethyl ester, mono-n-butyl ester, etc.); Salts (for example, ammonium salts, alkali metal salts and the like) can be exemplified. These monomers can be used alone or in combination of two or more. Among these carboxyl group-containing ethylene monomers, particularly preferred ones that can be used include acrylic acid, methacrylic acid and itaconic acid.

The synthetic rubber-based emulsion polymer particles used in the present invention comprise the above-mentioned conjugated diolefin-based monomer (a-1) and an aromatic vinyl monomer and / or a vinyl cyanide monomer (a). a-2) may be used as an essential monomer component, and more preferably a carboxyl group-containing ethylene monomer may be used in combination and copolymerized. If necessary, as is often the case in manufacturing,
Other monomers can be copolymerized.

Such other copolymerizable monomers (a-
Examples of 4) include the following.

Esters of acrylic acid or methacrylic acid: for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, iso-nonyl acrylate, methyl _C1-18 alkyl esters of acrylic acid or methacrylic acid such as methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate and n-dodecyl methacrylate.

Radical polymerizable unsaturated monomer containing at least one crosslinkable functional group: for example, acrylamide, methacrylamide, diacetoneacrylamide, N
Amides or derivatives of α, β-unsaturated carboxylic acids such as -methylolacrylamide, N-methylolmethacrylamide and the like; of α, β-unsaturated carboxylic acids such as glycidyl acrylate and glycidyl methacrylate with saturated alcohols having an epoxy group Esters: 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc., esters of α, β-unsaturated carboxylic acid and polyhydric saturated alcohol; dimethylaminoethyl methacrylate Esters of an α, β-unsaturated carboxylic acid such as diethylaminoethyl methacrylate and a saturated alcohol having an amino group; divinylbenzene, diallyl phthalate, triallyl cyanurate,
Monomers having two or more radical polymer unsaturated groups such as ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol dimethacrylate, allyl methacrylate; and the like.

The proportion of the above-mentioned monomer components (a-1) to (a-4) can be used in a wide range depending on the physical properties required for the synthetic rubber emulsion polymer particles to be formed. Can be used, but usually, it can be used within the range shown below.

[0032]

Table 1 General range Preferred range More preferred monomer (% by weight) (% by weight) Range (% by weight) (a-1) 30 to 90 40 to 80 45 to 75 (a-2) 10 -70 15-55 20-50 (a-3) 0.1-10 0.5-5 1-4 (a-4) 0-200 0-100-5 Note: Weight% is the sum of monomers Percentage based on volume.

Synthetic rubber-based latex polymer particles (A)
Are the monomer components (a-1) to (a-
4) in an aqueous medium in the presence of a surfactant and, if necessary, in the presence of a protective colloid, at a temperature of about 30 to about 100 ° C. in the same manner as in a method for producing a synthetic rubber-based latex known per se.
Preferably at a temperature of about 40 to about 90 ° C, usually under pressure,
It can be produced by emulsion polymerization.

As the surfactant, any of nonionic, anionic, cationic and amphoteric surfactants can be used. Nonionic surfactants include, for example, polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyalkylene alkyl phenol ethers such as polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether Sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monostearate and sorbitan trioleate; polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate and polyoxyethylene mono Polyoxyalkylene fatty acid esters such as stearates; oleic acid monoglyceride, stearic acid monoglyceride, etc. And the like. Examples of anionic surfactants include fatty acid salts such as sodium stearate, sodium oleate and sodium laurate; dodecylbenzene sulfone Alkyl aryl sulfone hydrochlorides such as sodium oxalate; alkyl sulfates such as sodium lauryl sulfate; alkyl sulfosuccinates such as sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium polyoxyethylene lauryl sulfosuccinate and derivatives thereof; Polyoxyalkylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate; polyoxyethylene nonylphenol Polyoxyalkylene alkylaryl ether sulfate ester salts such as ether sodium sulfate; or the like can be exemplified, and as the cationic surfactant include alkylamine salts such as laurylamine acetate; lauryl trimethyl ammonium chloride,
Quaternary ammonium salts such as alkylbenzyldimethylammonium chloride; polyoxyethylalkylamine; and the amphoteric surfactants include, for example, alkyl betaines such as lauryl betaine. Further, those obtained by substituting a part of the hydrogen of the alkyl group of these surfactants with fluorine; so-called reactive surfactants having a radical copolymerizable unsaturated bond in the molecular structure of these surfactants; Can be used.

Among these surfactants, nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl phenol ethers, and the like, from the viewpoint of the generation of small aggregates during emulsion polymerization. Examples of the anionic surfactant include alkyl aryl sulfonates, alkyl sulfates, alkyl sulfosuccinates and derivatives thereof, polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl phenol ether sulfates, and the like. Is preferred. These surfactants can be used alone or in appropriate combination.

The amount of these surfactants can be varied depending on the type of surfactant used, etc., but generally, the total of the monomer components (a-1) to (a-4) is 100 parts by weight. The aqueous coating composition can be in the range of about 0.5 to about 10 parts by weight, based on the polymerization stability of the aqueous emulsion polymerization, the storage stability of the resulting synthetic rubber-based polymer emulsion, and the chipping-resistant aqueous coating composition. When used in the above, from the viewpoint of excellent adhesion to a substrate such as a sheet metal processing member, about 1 to 6
It is preferred to use it in parts by weight, especially in the range of about 1 to 4 parts by weight.

Examples of protective colloids that can be used in the production of synthetic rubber polymer emulsions include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; hydroxyethyl cellulose; Cellulose derivatives such as hydroxypropylcellulose and carboxymethylcellulose; natural polysaccharides such as guar gum; and the like.

The use amount of these protective colloids is not strictly limited, and can be changed according to the kind and the like. Usually, the amount of the monomer components (a-1) to (a-4) is not limited. The amount can be, for example, about 0 to 3 parts by weight based on 100 parts by weight in total.

The monomer components (a-1) to (a-
The emulsion polymerization of 4) is performed using a polymerization initiator. Examples of usable polymerization initiators include, for example, persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate; and organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide and p-menthane hydroperoxide. And hydrogen peroxide; and these can be used alone or in combination of two or more.

The amount of the polymerization initiator used is not strictly limited, and can be varied in a wide range depending on the type, reaction conditions, and the like. ) To (a-4), relative to a total of 100 parts by weight, about 0.05 to about 1 part by weight, more preferably about 0.1 to about 1 part by weight.
Amounts such as about 0.7 parts by weight, particularly preferably about 0.1 to about 0.5 part by weight, can be exemplified.

In the emulsion polymerization, a reducing agent can be used together if desired. Examples of the reducing agent that can be used include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, and glucose; and reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite. Examples can be given. The amount of these reducing agents is not particularly limited either, but is generally about 0.05 to 5 parts by weight based on a total of 100 parts by weight of the monomers (a-1) to (a-4).
A range of about 1 part by weight can be exemplified.

In the emulsion polymerization, a chain transfer agent can be used if desired. Such chain transfer agents include, for example, cyanoacetic acid;
_1-8 alkyl esters; bromoacetic acid; C of bromoacetic acid
_1-8 alkyl esters; polycyclic aromatic compounds such as anthracene, phenanthrene, fluorene and 9-phenylfluorene; p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p Aromatic nitro compounds such as -nitrotoluene; benzoquinone derivatives such as benzoquinone, 2,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride; One,
Halogenated hydrocarbons such as 2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane and 3-chloro-1-propene; aldehydes such as chloral and furaldehyde; for example, n-dodecyl C _{1 to 18} alkyl mercaptans such as mercaptan; thiophenol, aromatic mercaptans such as toluene mercaptan; mercaptoacetic acid; C _{1 to 10} alkyl esters of mercaptoacetic acid; 2-mercapto C _{1 to 12} hydroxy Le alkyl such as ethanol Mercaptans; terpenes such as binene and terpinolene; and the like.

When the above-mentioned chain transfer agent is used, the amount of the above-mentioned chain transfer agent is 10% in total of the monomers (a-1) to (a-4).
It is preferably in the range of about 0.005 to about 3.0 parts by weight, based on 0 parts by weight.

The synthetic rubber-based polymer emulsion (latex) formed by the emulsion polymerization described above generally contains 10 to 70% by weight, preferably 30 to 65% by weight,
More preferably, it can have a solids content in the range of 40 to 60% by weight, and can be measured by using a B-type viscometer.
The viscosity measured at 20 ° C. and 20 rpm is typically 1000
It is desirably 0 cps or less, particularly in the range of about 50 to about 5000 cps.

The above emulsion is generally used in an amount of 2 to 10, especially 5
It is desirable to have a pH in the range of -9, and the pH can be adjusted using, for example, aqueous ammonia, an aqueous amine solution, or an aqueous alkali hydroxide solution.

The synthetic rubber emulsion polymer particles (A) used in the aqueous coating composition of the present invention have a Tg
Is 0 ° C. or lower, preferably -10 ° C. or lower, more preferably -20 to −80 ° C. A coating film formed from an aqueous coating composition prepared using synthetic rubber emulsion polymer particles having a Tg higher than 0 ° C. generally has low chipping resistance and is not preferred.

In the present specification, the glass transition temperature (Tg) of the polymer particles is a value measured by the following method.

Glass transition point (Tg) : thickness about 0.05 m
m aluminum foil, inner diameter about 5mm, depth about 5mm
Approximately 10 mg of the (co) polymer emulsion sample was weighed into a cylindrical cell of No. 1, and dried at 100 ° C. for 2 hours to obtain a measurement sample, which was taken as a differential scanning calorimeter [Differentia
l Scanning Colorimeter: SSC-5000 type manufactured by Seiko Instruments Inc.]
The difference in specific heat capacity before and after the glass transition temperature of the sample is measured from 150 ° C. at a heating rate of 10 ° C./min, and Tg is determined from the result.

The synthetic rubber emulsion polymer particles desirably have a gel fraction in the range of generally 60 to 98% by weight, particularly preferably 70 to 95% by weight.

In this specification, the gel fraction of the synthetic rubber emulsion polymer particles (A) is a value measured by the following method.

Gel fraction : A film was prepared from a synthetic rubber-based polymer emulsion by drying at room temperature, and the film was dried for about 2 hours.
No. 00-800 times in toluene and left for 48 hours. 2 Filter using filter paper. Filtrate at 70 ° C
And then weighed to determine the toluene-soluble matter (% by weight) of the film from the polymer emulsion.
The value obtained by subtracting the above-mentioned toluene-soluble matter (% by weight) from the above, that is, the toluene-insoluble matter (% by weight) is defined as the gel fraction.

Further, the average particle size of the synthetic rubber polymer particles (A) dispersed in the emulsion produced as described above (hereinafter, may be simply referred to as the particle size) is as follows:
Generally, it is desirable to be in the range of 0.05-0.5 microns, especially 0.1-0.3 microns. The control of the particle size of the polymer particles in the emulsion can be performed, for example, by appropriately selecting the type and amount of the surfactant to be used, the polymerization temperature, and the like.

In the present specification, the average particle diameter of the polymer particles is described in “New Experimental Chemistry Course 4 Basic Technology 3 Light (II)”, edited by The Chemical Society of Japan, pp. 725-741 (July 1971). This is a value measured by the DLS method described in 20th Maruzen Co., Ltd.), and specifically, a value measured and determined by the method described below.

Average particle diameter : The (co) polymer emulsion was diluted 50,000 to 150,000 times with distilled water, mixed well with stirring, and about 10 ml was collected in a 21 mmφ glass cell using a Pasteur pipette. This is a dynamic light scattering photometer DLS
-700 [manufactured by Otsuka Electronics Co., Ltd.] is set at a predetermined position, and the measurement is performed under the following measurement conditions.

Measurement conditions Measurement temperature 25 ± 1 ° C. Clock rate (Clock Rete) 10 μsec Correlation channel (Corel. Channel) 512 Total number of measurements 200 times Light scattering angle 90 ° The measurement results are processed by computer to determine the average particle diameter.

Synthetic rubber emulsion polymer particles (A)
Are, in addition to those manufactured by the method described above, for example, L
X-407C [manufactured by Nippon Zeon Co., Ltd.], SN-318, S
N-534, SN-562, J-1666 [manufactured by Sumitomo Dow Co., Ltd.], SK-80 [manufactured by Takeda Pharmaceutical Co., Ltd.],
L-2001, L-2337 [or more, Asahi Kasei Industry Co., Ltd.
Styrene-butadiene-based synthetic rubber latex (hereinafter sometimes abbreviated as SBR) sold under trade names such as Polylac 707 (manufactured by Mitsui Toatsu Chemicals, Inc.); Nipol 1571, Nipol 1551; Acrylonitrile-butadiene-based synthetic rubber latex (hereinafter sometimes abbreviated as NBR) or the like, which is commercially available under a trade name such as Nipol 1562 [manufactured by Zeon Corporation], can also be used.

High Tg emulsion polymer particles (B) In the aqueous coating composition of the present invention, a high Tg emulsion polymer used as a vehicle component in combination with the synthetic rubber emulsion polymer particles (A) described above. The particle (B) has the formula

[0058]

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In the formula, R ¹ represents a hydrogen atom or a methyl group, and Q represents —COOR ² ,

[0060]

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Or --CN, wherein R ² represents a lower alkyl group, and R ³ represents a hydrogen atom or a lower alkyl group. 99.9% by weight, preferably 35-9
(Co) polymer containing 8.5% by weight, more preferably 40 to 96% by weight, and optionally containing one or more other monomer units. It is composed.

Here, the term “lower” means that the group or compound to which this term is attached has 6 or less, preferably 4 or less carbon atoms.

Suitable as such another monomer unit is a repeating unit derived from a carboxyl group-containing ethylenic monomer described later, and the (co) polymer preferably contains such a unit in an amount of 0%. 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. Further, the (co) copolymer may contain a repeating unit derived from a hydroxyl group-containing ethylenic monomer described later, preferably in an amount of 1 to 20% by weight, particularly preferably 3 to 15% by weight.

The (co) polymer is, for example, represented by the formula (b-1)

[0065]

Embedded image In the formula, R ¹ and Q are as defined above, an ethylene monomer represented by the formula: wherein the homopolymer of the monomer is hydrophobic and has a Tg of 40 ° C. or higher. And (b-2) a carboxyl group-containing ethylene monomer, preferably (b-3) a hydroxyl group-containing ethylene monomer and, if necessary, (b-4) another copolymerizable monomer. It can be produced by emulsion polymerization with a monomer.

As the monomer (b-1), for example,
Methyl methacrylate, ethyl methacrylate, iso
C _1-4 of methacrylic acid such as -butyl methacrylate
Alkyl esters; aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and ethylvinylbenzene; (meth) acrylonitrile; Among these, methyl methacrylate, styrene and acrylonitrile are preferred as the monomer (b-1) from the viewpoints of availability, ease of emulsion polymerization, and the like. These monomers can be used alone or in combination of two or more.

The carboxyl group-containing ethylene monomer (b)
-2) is a carboxyl group-containing ethylene monomer (a-
The same thing as 3) can be used. Preferred as the monomer (b-2) are acrylic acid, methacrylic acid and itaconic acid as in the monomer (a-3).

Further, a hydroxyl group-containing ethylene monomer (b-
3) includes α, β-ethylenically unsaturated monomers containing 1 to 4, preferably 1 hydroxyl group in one molecule, for example, 2-hydroxyethyl (meth) acrylate, Examples include _C2-4 hydroxyalkyl esters of (meth) acrylic acid such as -hydroxypropyl (meth) acrylate.

Further, other copolymerizable monomers that can be used as required include “other copolymerizable monomers (a-4)” in the production of the synthetic rubber-based copolymer. _C1-12 saturated fatty acid vinyl monomers such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate (trade name); ethylene, propylene, n-butylene, i -Monoolefin monomers such as butylene; butadiene, isoprene,
Conjugated diolefin-based monomers such as chloroprene; dibutyl malate, dioctyl malate, dibutyl fumarate,
Di-C _1-12 alkyl ester monomers of C _4-5 unsaturated α, β-dicarboxylic acids such as dioctyl fumarate, dibutyl itaconate and dioctyl itaconate; and the like can also be used. The above-mentioned monomers can be used alone or in combination of two or more. These monomers may have desired physical properties such as Tg
Can be appropriately selected according to the above, and among them, vinyl acetate, vinyl versatate (trade name), and butadiene are preferable.

The monomers (b-1) to (b-
4) can be produced by the same emulsion polymerization method as that described above for the method of producing the synthetic rubber-based latex polymer particles (A) (usually emulsion polymerization under atmospheric pressure).

In the aqueous coating composition of the present invention, the high Tg emulsion polymer particles (B) used in combination with the aforementioned synthetic rubber emulsion polymer particles (A) as a vehicle component have a Tg of Those that are at least 20 ° C. are used. The glass transition temperature (Tg) required for the polymer particles (B) is desirably adjusted according to the baking temperature of the coating film formed from the final coating composition. In the case of a coating composition for low temperature baking at about 100 ° C., the polymer particles (B) used
Conveniently, the Tg is in the range of from 20 ° C to less than 60 ° C, preferably from 30 ° C to 55 ° C,
In the case of a coating composition for high-temperature baking having a baking temperature of about 120 to about 160 ° C., the T of the polymer particles (B) blended therein is reduced.
g is generally above 60 ° C., especially above 70 ° C., more especially 8 ° C.
It is desirable that the temperature is 5 ° C. or higher. Thus, for the monomers (b-1) to (b-4) for producing the high Tg polymer particles (B), the type and use ratio of each monomer are selected so as to satisfy the above Tg. For emulsion polymerization. The following ranges can be exemplified as the general range of the usage ratio of these monomers.

Monomer (b-1): 30 to 99.9% by weight Monomer (b-2): 0.1 to 10% by weight Monomer (b-3): 0 to 30% by weight Monomer (b-4): 0 to 70% by weight Note:% by weight is a percentage based on the total amount of monomers.

The preferred proportion of each monomer component depends on the application (for low-temperature baking or high-temperature baking) of the aqueous coating composition into which the high Tg polymer particles (B) to be formed are blended. , Can be selected from the following range.

(1) In the case of the high Tg polymer particles (B) used in the aqueous coating composition for low-temperature baking:

[0075]

[Table 2] (2) In the case of the high Tg polymer particles (B) used in the aqueous coating composition for high temperature baking:

[0076]

[Table 3] The (co) copolymer emulsion formed by emulsion polymerization of these monomers (b-1) to (b-4) contains 10 to 70% by weight of the high Tg polymer particles (B) as a solid content. , Preferably 30 to 65% by weight, more preferably 40 to 60% by weight, and the viscosity measured at 25 ° C. and 20 rpm using a B-type rotational viscometer is usually Conveniently below 10,000 cps, especially in the range of about 10 to about 5000 cps.

The above emulsion is generally used in an amount of 2 to 10, especially 5
It is desirable to have a pH in the range of -9, and the pH can be adjusted using, for example, aqueous ammonia, an aqueous amine solution, or an aqueous alkali hydroxide solution.

The high Tg emulsion polymer particles (B)
Generally, it is desirable to have a weight average molecular weight of 500,000 or more, especially 800,000 or more. Further, high Tg polymer particles (B) dispersed in the formed polymer emulsion
Is preferably in the range of generally 0.05 to 0.5 micron, particularly preferably 0.1 to 0.3 micron,
The control of the particle size of the high Tg polymer particles (B) can be performed in the same manner as the control of the particle size of the synthetic rubber emulsion polymer particles (A).

Urethane Emulsion Polymer Particles (C) The urethane emulsion polymer particles (C) which can be appropriately blended with the aqueous coating composition of the present invention are known per se in the field of paints and adhesives. Can be used.

The urethane polymer emulsion is as follows:
According to a usual method, it can be prepared by reacting a chain extender with a urethane prepolymer having an isocyanate group at a terminal obtained from a polyisocyanate compound and a polyol compound, followed by emulsification.

Examples of the polyisocyanate compound which can be used in producing the urethane emulsion polymer (C) include 1,3- or 1,4-phenylenediisocyanate, 2,4- or 2,6-tolylenediisocyanate,
Aromatic polyisocyanate compounds such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, and 1,3-xylylene diisocyanate; 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-
Aliphatic polyisocyanate compounds such as 1,6-hexamethylene diisocyanate, 1,8-octamethylene diisocyanate, and 1,10-decamethylene diisocyanate;
1,3- or 1,4-cyclohexylene diisocyanate, 1-methylcyclohexane-1,3- or 1,4-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,3-isocyanomethylcyclohexane, etc. Aliphatic polyisocyanate compound; and the like. Among these polyisocyanate compounds, preferred are, for example, 2,4- or 2,6-tolylene diisocyanate,
Examples thereof include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and isophorone diisocyanate.

The polyol compound which can be reacted with the above-mentioned polyisocyanate compound includes polyester polyols, polyether polyols and polyester ether polyols. Examples of the polyol compound include polyester polyols, polyether polyols and polyester ether polyols. and so on. Examples of the polyester polyols include, for example, polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitan, and sorbitol; Polyvalents such as acid, adipic acid, sebacic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, icotanic acid, glutaric acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, trimellitic acid, dodecanedicarboxylic acid, etc. Examples thereof include condensates with carboxylic acids and lactone polymers. Examples of the polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethylene propylene glycol. Polyalkylene glycols such as coal may be mentioned.As the polyester ether polyols, those obtained by adding an alkylene oxide such as ethylene oxide to the above polyester polyols, and the above polyether polyols and the above polycarboxylic acids are condensed. Those having a hydroxyl group at the terminal can be exemplified.

As the chain extender, at least two functional groups containing an active hydrogen atom which reacts with an isocyanate group are used.
Compounds having two or more compounds can be used, and typical examples thereof include water, polyhydric alcohols, primary and secondary polyamines, hydrazine and derivatives thereof.

The above polyhydric alcohols include, for example,
Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2- or 1,3-propylene glycol, 1,2-, 1,3- or 1,4-butylene glycol, 2,2-dimethyl-1, 3-
Propylene glycol, 1,6-hexanediol, 2,
Aliphatic diols such as 2,4-trimethyl-1,3-pentanediol; alicyclic rings such as 2,2,4,4-tetramethylcyclobutanediol, 1,3-cyclopentanediol, and methylenebis (4-cyclohexanol) Diols; 1,4
-Phenylenebis (2-hydroxyethyl ether),
Aromatic diols such as 1,2-propylene glycol bis (2-hydroxyphenyl ether); Examples of polyvalent amines include ethylenediamine, hexamethylenediamine, isophoronediamine, diaminodiphenylmethane, diethylenetriamine, and the like. Examples of hydrazine derivatives include dimethylhydrazine and 1,6-hexamethylenebis Substituted hydrazines such as hydrazine; reaction products of dicarboxylic acids, disulfonic acids, lactones or polyhydric alcohols with hydrazine;

Other examples of the chain extender include those used for imparting ionicity to urethane prepolymers and urethane-based resins when emulsifying them, and specific examples thereof include: For example,
Dihydroxycarboxylic acids such as 2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid; 2,5-diaminobenzoic acid, α, ε-caproic acid (Lysine), diaminocarboxylic acids such as 2-amino-5-guanidinovaleric acid (arginine); alkyl dialkanolamines such as methyldiethanolamine; and the like.

The urethane prepolymer having an isocyanate group at the terminal can be prepared, for example, by using the polyisocyanate compound and the polyol compound in such a ratio that the isocyanate group is in excess equivalent to the hydroxyl group in a nitrogen atmosphere. About 25-110 with stirring in organic solvent
It can be produced by reacting at a temperature of ° C., if necessary, in the presence of a catalyst.

Examples of the organic solvent usable herein include ketones such as acetone and methyl ethyl ketone; ethers such as dioxane and tetrahydrofuran;
Esters such as ethyl acetate; aliphatic hydrocarbons such as heptane and octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Useful reaction catalysts include, for example, tertiary amines such as triethylamine; inorganic salts such as stannous chloride; di-n-
Organometallic compounds such as butyltin dilaurate; and the like.

The production of the urethane polymer emulsion from the urethane prepolymer and the chain extender prepared as described above can be carried out by various methods known per se.

The cationic emulsion may be produced, for example, by (1) polymerizing a urethane prepolymer having an isocyanate group at a terminal with a diol having a tertiary amino group as a chain extender, and then quaternizing the polymer. Or a method of cationizing with an acid or reacting with a diol having a quaternary amino group as a chain extender, (2) converting a urethane prepolymer having an isocyanate group at a terminal into a polyalkylene as a chain extender After polymerizing using a polyamine, a method of reacting epihalohydrin with an acid to cationize the compound may be used.

The anionic emulsion can be produced, for example, by (3) polymerizing a urethane prepolymer having an isocyanate group at a terminal using a dihydroxycarboxylic acid or a diaminocarboxylic acid as a chain extender, and then adding an alkaline solution. (4) Urethane prepolymer having terminal isocyanate groups obtained from a hydrophobic polyol and an aromatic polyisocyanate is sulfonated and neutralized with a tertiary amine to be anionized. Method and the like.

Further, as a method for producing a nonionic emulsion, for example, (5) a urethane prepolymer having an isocyanate group at a terminal is dispersed in an aqueous solution containing a diamine or the like as necessary using an emulsifier, and A method of extending the chain with a diamine, (6) reacting an alkylene oxide condensate of a long-chain alcohol (a type of nonionic surfactant) with an amine having a hydrophilic group such as a hydroxyl group on a urethane prepolymer having an isocyanate group at the terminal. Method,
(7) A method of reacting the above-mentioned chain extender with a urethane prepolymer having an isocyanate group at a terminal to form a urethane resin, and mechanically dispersing the resin in water using an emulsifier can be used.

As the urethane polymer emulsion usable in the present invention, in addition to those described above, a hydroxyl group-containing vinyl monomer such as 2-hydroxyethyl acrylate is introduced into a urethane prepolymer. An emulsion copolymerization of the urethane prepolymer and the (meth) acrylic monomer; one part of the isocyanate group of the urethane prepolymer having an isocyanate group at the terminal is blocked with various blocking agents, By reacting a urethane prepolymer or a urethane-based polymer with a urethane prepolymer in which one part of an isocyanate group is blocked, the urethane prepolymer or urethane-based polymer containing a blocked isocyanate in the molecule is obtained. Emulsified in the same manner as described above; Wear.

Among these, the urethane polymer emulsion is prepared by mixing the synthetic rubber-based emulsion polymer particles (A) and the high Tg emulsion polymer particles (B) with each other. It is preferable to use an anionic or nonionic emulsion from the viewpoints of ease of preparation, storage stability of the final coating composition, and the like.

The average particle size of the polymer particles in the urethane polymer emulsion produced as described above is generally 0.05 to 0.5 μm, preferably 0.1 μm.
Desirably, it is in the range of ~ 0.3 microns.

Further, the urethane emulsion polymer particles (C) are used in view of the degree of improvement in the prevention of blistering at the time of baking of a coating film formed using the final coating composition, the wet chipping resistance, and the like. Of a film formed from a urethane-based polymer emulsion containing the polymer particles (C).
The stress at the time of extension at 100% or less, sometimes 100% modulus, or the yield value before 100% extension, whichever is greater, is generally 20 kg / cm ² or more, preferably 3 kg / cm ² or more.
0 kg / cm ² or more, more preferably 40 to 300 k
It is desirably within the range of g / cm ² .

In this specification, the 100% modulus and the yield value of a film formed from a urethane polymer emulsion are values measured by the following methods.

100% modulus and yield value of the film
Measurement method : A urethane polymer emulsion is applied on a release paper fixed horizontally by a doctor blade to a dry thickness of 50 to 100 μm, dried at room temperature, and then dried at 120 ° C. by a hot air circulation type dryer. Heat treatment for 10 minutes to form a urethane polymer film. After leaving the obtained film under a constant temperature and humidity condition of 23 ° C. and 65% RH for 3 hours or more, a stress-elongation curve is measured under the same condition, and a required numerical value is read from the curve.

For the measurement, "Tensilon UTM-4-10
0 "[manufactured by Toyo Baldwin Co., Ltd.]
m, gripping interval 10 mm and pulling speed 100 mm / mi
Used for n.

Aqueous coating composition : The aqueous coating composition of the present invention is prepared by adding an inorganic filler to the synthetic rubber polymer emulsion (A) and the high Tg polymer emulsion (B) prepared as described above. Can be prepared.

The above polymer emulsions (A) and (B)
Of the polymer particles (A) in these emulsions
And (B) (i.e., the solid content),
50 to 95 for synthetic rubber emulsion polymer particles (A)
%, Preferably 55 to 90% by weight, more preferably 60 to 85% by weight, and the high Tg emulsion polymer particles (B) comprise 5 to 50% by weight, preferably 10 to 50% by weight.
To 45% by weight, more preferably 15 to 40% by weight.

The above-mentioned aqueous coating composition may optionally contain the urethane polymer emulsion (C) described above.
Which can significantly improve the wet chipping resistance of a coating film formed from the coating composition and the adhesion to a substrate, especially a cationic electrodeposition coated steel sheet. The amount is in the range of 3 to 100% by weight based on the solid content, that is, urethane emulsion polymer particles, based on the total amount of synthetic rubber emulsion polymer particles (A) and high Tg emulsion polymer particles (B). In the case of the aqueous coating composition for low temperature baking, the content is preferably in the range of 20 to 90% by weight, particularly 30 to 80% by weight, while the composition for aqueous coating for high temperature baking is preferred. In this case, the content is preferably in the range of 4 to 70% by weight, particularly 5 to 50% by weight.

On the other hand, the aqueous medium used in the aqueous coating composition of the present invention is derived from the above-mentioned emulsion, and is usually water. In some cases, water and a water-miscible organic solvent may be used. May be used as a mixed solvent.

Further, in the aqueous coating composition of the present invention, the inorganic filler is added to the composition for the purpose of increasing the amount of the filler, adjusting the hardness of the coating, preventing the generation of blisters, and the like. Possible inorganic fillers include inorganic solid powders substantially insoluble or hardly soluble in water, for example, calcium carbonate, silica, alumina, kaolin, clay, talc, diatomaceous earth, mica, aluminum hydroxide, glass powder,
Examples thereof include barium sulfate and magnesium carbonate.

The blending amount of these inorganic fillers can be varied in a wide range depending on the kind and physical properties desired for the coating composition, but the fine polymer particles contained in the composition can be varied. [Namely, the total of the synthetic rubber-based emulsion polymer (A), the high Tg emulsion polymer particles (B), and the urethane-based emulsion polymer particles (C) contained as required] is generally 100 parts by weight. It can be in the range of 100 to 390 parts by weight, preferably 120 to 380 parts by weight, more preferably 150 to 300 parts by weight.

The above-mentioned inorganic filler is generally used in an amount of about 0.1.
It is desirable to have an average particle size in the range of 5 to about 50 microns, especially 1 to about 30 microns.

The coating composition of the present invention may optionally contain
As in the ordinary coating composition, it can contain a rust preventive pigment, a coloring pigment, a crosslinking agent and the like.

Examples of the above rust-preventive pigments include lead red; metal chromate salts such as zinc chromate, barium chromate and strontium chromate; zinc phosphate, calcium phosphate, aluminum phosphate, titanium phosphate, and silicon phosphate. ,
Or metal phosphates such as ortho or condensed phosphates of these metals; molybdenum such as zinc molybdate, calcium molybdate, zinc calcium molybdate, zinc potassium molybdate, zinc potassium phosphomolybdate, calcium potassium phosphomolybdate Acid metal salts; metal borate salts such as calcium borate, zinc borate, barium borate, barium metaborate, and calcium metaborate; and the like. Among these rust preventive pigments, non-toxic or low-toxic rust preventive pigments such as metal phosphates, metal molybdates and metal borates are preferred.

The amount of the rust preventive pigment is, for example, from 0 to 100 parts by weight of the polymer fine particles in the coating composition.
An example is 50 parts by weight, preferably 5 to 30 parts by weight.

Examples of the coloring pigment include organic or inorganic coloring pigments such as titanium oxide, carbon black, red iron oxide, Hansa Yellow, Benzidine Yellow, Phthalocyanine Blue, and quinacridone red. The mixing amount of these coloring pigments is, for example, from 0 to 1 based on 100 parts by weight of the polymer fine particles in the coating composition.
0 parts by weight, preferably in the range of 0.5 to 5 parts by weight.

The particle size of the rust-preventive pigment and the color pigment is preferably in the range of 1 to 50 μm from the viewpoint of the smoothness of the formed film of the coating composition to be obtained.

Further, as a crosslinking agent which can be appropriately compounded,
(A) water-soluble polyvalent metal salts, for example, zinc salts such as zinc acetate, zinc formate, zinc sulfate, and zinc chloride; aluminum salts such as aluminum acetate, aluminum nitrate, and aluminum sulfate; calcium acetate, calcium iodate, calcium chloride; Calcium salts such as calcium nitrate and calcium sulfite; barium salts such as barium acetate, barium chloride and barium sulfite; magnesium acetate, magnesium formate;
Magnesium salts such as magnesium chloride, magnesium sulfate, magnesium nitrate and magnesium sulfite; lead acetate;
Lead salts such as lead formate; nickel salts such as nickel acetate, nickel chloride, nickel nitrate and nickel sulfate; manganese salts such as manganese acetate, manganese chloride, manganese sulfate and manganese nitrate; (B) an aziridine compound, for example, a reaction product of a polyisocyanate compound and ethyleneimine;
(C) polyisocyanate compounds such as m- or p-phenylenediisocyanate, 2,4- or 2,6-
Aromatic diisocyanate compounds such as tolylene diisocyanate, m- or p-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate; hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated aromatic diisocyanate compounds,
Aliphatic or alicyclic diisocyanate compounds such as dimer acid diisocyanate; dimers or trimers of these isocyanates; adducts of these isocyanates with divalent or trivalent polyols such as ethylene glycol and trimethylolpropane (E) a water-soluble melamine resin such as glycerol diglycidyl ether; and (e) a water-soluble melamine resin such as methylol melamine; at least a part of the hydroxyl group of the methylol melamine is methyl alcohol, ethyl alcohol, n-
Such as those etherified with butyl alcohol, etc.
(F) Water-dispersible blocked isocyanates, for example, trimethylolpropane tolylene diisocyanate methyl ethyl ketoxime adduct; adducts of the above polyisocyanate compounds and volatile low molecular weight active hydrogen-containing compounds.

Examples of the compound containing a volatile active hydrogen molecule include methyl alcohol, ethyl alcohol, and the like.
aliphatic, alicyclic or aromatic alcohols such as n-butyl alcohol, cyclohexyl alcohol, benzyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and phenol; hydroxy tertiary amines such as dimethylaminoethanol and diethylaminoethanol; And ketoximes such as acetoxime and methylethylketoxime; for example, active methylene compounds such as acetylacetone, acetoacetate and malonate; lactams such as ε-caprolactam; and the like.

The amount of the crosslinking agent to be used is, for example, from 0 to 100 parts by weight of the polymer fine particles in the composition for coating obtained from the viewpoint of suppressing the change of the viscosity of the coating composition with time.
The range is 10 parts by weight, preferably 0.5 to 10, particularly preferably 1 to 5 parts by weight.

The aqueous coating composition of the present invention may further contain an inorganic dispersant [eg, sodium hexametaphosphate, sodium tripolyphosphate, etc.] and an organic dispersant [eg, Nopcosperse 44C (trade name, Polycarbonate)] Dispersants such as silicon-based defoamers; thickeners and viscosity improvers such as polyvinyl alcohol, cellulose derivatives, polycarboxylic acid-based resins, and surfactants; ethylene; Organic solvents such as glycol, butyl cellosolve, butyl carbitol, and butyl carbitol acetate; antioxidants; preservatives and fungicides; ultraviolet absorbers; antistatic agents;

The aqueous coating composition of the present invention is generally, but not limited to, about 40 to about 90% by weight,
Preferably about 50 to about 85% by weight, particularly preferably about 6
It contains solids in the range of 0-80% by weight,
11, preferably having a pH in the range of 8 to 10 and from about 3,000 to about 100,000 cps, preferably about 5,
It can have a viscosity in the range of 000 to about 50,000 cps (B-type rotational viscometer, at 25 ° C., 20 rpm).

The substrate to which the aqueous coating composition of the present invention can be applied is not particularly limited. For example, a steel sheet; for example, a lead-tin alloy plated steel sheet (tan sheet steel sheet), a tin plated steel sheet, an aluminum plated steel sheet And various types of plated steel sheets such as lead-plated steel sheets, chromium-plated steel sheets, and nickel-plated steel sheets; coated steel sheets such as electrodeposited coated steel sheets;

The coating composition of the present invention is, in particular, one obtained by molding such a base material into various shapes by a sheet metal press or the like, or one obtained by welding them as various automotive members.
For example, it can be suitably used for coating an electrodeposition-coated surface, a middle-coated surface, or a top-coated surface of a sheet metal processing member outside a vehicle cabin such as a gasoline tank of an automobile, an under floor, a tire house, a front apron, and a rear apron. it can.

The coating composition of the present invention can be applied by a coating method known per se, for example, brush coating, spray coating, roller coating, etc., but airless spray coating is generally preferred.

The coating thickness at this time varies depending on the use of the base material and the like, but is usually in the range of about 200 to about 800 microns, especially about 300 to about 600 microns. The coating film can be dried by natural drying, heat drying, or the like. In general, in the case of an aqueous coating composition for low-temperature baking, baking is performed in a heating furnace at a temperature of about 60 to about 100 ° C. In the case of an aqueous coating composition for high temperature baking, it is preferable to pre-dry at a temperature of about 60 to about 100 ° C. and then bake in a heating furnace at a temperature of about 120 to about 160 ° C. It is convenient.

Hereinafter, the present invention will be described more specifically with reference to examples.

The preparation of test samples used in the examples and comparative examples and the test method are as follows.

(1) Preparation of Test Specimen Each sample was coated on a predetermined steel plate having a thickness of 0.8 × 100 × 200 mm by an airless spray coating method so that a dry coating film had a predetermined thickness, and was heated with hot air. Heat treatment is performed under predetermined conditions using a circulation dryer.

(2) Limiting film thickness of blister In the spray coating in the preceding paragraph (1), coating was performed by changing the thickness of the dried coating film, and the maximum film thickness that would not cause blistering during drying was determined. Thickness.

(3) Adhesion test In the preceding paragraph (1), a test piece obtained by coating so as to have a dry film thickness of about 300 μm was obtained using a Goban tester (manufactured by Suga Test Instruments Co., Ltd.). 1m vertically and horizontally from the painted surface
1cm ²
Create 100 Goban eyes inside. 2
A 4 mm wide cellophane tape (manufactured by Nichiban Co., Ltd.) is adhered, and 180 ° peeling is quickly performed by hand. The number of eyes remaining on the coating film is counted and indicated as “number of remaining coating films / 100”.

(4) Normal chipping resistance test The test piece obtained by coating the dried film thickness of about 300 μm in the previous section (1) was subjected to a constant temperature condition of about 25 ° C. for 16 hours.
After leaving for a period of time, an office cutter is used to make a cut line of about 5 cm in length at a depth reaching the substrate from the coating film surface.

The test piece was fixed upright at an angle of 60 ° with respect to the horizontal plane, and a nut (M-6) was cut on the coated surface using a 25 mmφ PVC pipe from a height of 2 m in the vertical direction. Drop it continuously against the cross section, ED
The evaluation is based on the total weight of the dropped nuts when the base of the plate is exposed.

(5) Wet chipping resistance test In the above item (1), a test piece obtained by coating so as to have a dry film thickness of about 300 μm was placed in deionized water at about 40 ° C.
After immersion for a day, take out and wipe off the moisture, then (4)
A cut line marked with “x” is made in the same manner as described in the section, and after leaving it at 25 ° C. for 3 hours, a chipping resistance test is performed in the same manner as in the above section (4), and the same evaluation is made.

(6) Low-Temperature Impact Resistance Test In the preceding paragraph (1), the test piece was allowed to stand at a constant temperature of -30 ° C. for 3 hours or more and then JIS K-5400 at the same temperature.
Perform a DuPont type impact resistance test according to.

The condition at this time is that the tester has a radius of 6.35 ±
Attach a 0.33 mm shooting die and a pedestal, sandwich the test piece with the coating surface facing upward, drop a weight of 500 ± 1 g onto the shooting die from a height of 50 cm, and damage the coating surface Is visually evaluated according to the following evaluation criteria.

◎ ・ ・ ・ ・ ・ ・ ・ No change at all ○ ・ ・ ・ ・ ・ ・ ・ Slight crack generation △ ・ ・ ・ ・ ・ Small crack generation ×× ・ ・ ・ ・ Large crack generation

[0131]

EXAMPLES Reference Example 1 2000 ml equipped with a stirrer, a reflux condenser and a thermometer
A separable flask was charged with 250 parts by weight of deionized water, and heated to 80 ° C. while flowing nitrogen. Next, 233 parts by weight of deionized water and 10 parts by weight of sodium dodecylbenzenesulfonate (ABS) are placed in another container and stirred to form a uniform aqueous solution.
A monomer mixture obtained by uniformly mixing 5 parts by weight and 15 parts by weight of acrylic acid (AA) is dropped and stirred to form a monomer pre-emulsion. The pre-emulsion and a polymerization initiator aqueous solution of ammonium persulfate ( 30 parts by weight of a 5% by weight aqueous solution of APS) were continuously added over 3 hours, and then maintained at the same temperature for 1 hour.
The resulting mixture was added to obtain a styrene copolymer emulsion.

In the polymerization, the monomer composition, the solid content of the obtained copolymer emulsion, pH, viscosity, particle size,
Table 1 shows the Tg of the copolymer particles.

Reference Examples 2 to 3 Styrene copolymer emulsions having different particle diameters were obtained in substantially the same manner as in Reference Example 1 except that the amount of ABS used was changed. The monomer composition during these polymerizations, the solid content of the obtained copolymer emulsion, pH,
Table 1 shows the viscosity, particle diameter, and Tg of the copolymer particles.

REFERENCE EXAMPLES 4-5 In Reference Example 1, instead of using St485 parts by weight, St460 parts by weight and 2-hydroxyethyl methacrylate (HEMA) 25 parts by weight or St435 parts were used.
Reference Example 1 except that parts by weight and 50 parts by weight of HEMA were used.
In the same manner as in the above, a styrene copolymer emulsion was obtained. Table 1 shows the monomer composition, solid content, pH, viscosity, particle size, and Tg of the copolymer particles obtained during the polymerization.

Reference Examples 6 to 8 In Reference Example 1, instead of using St485 parts by weight, 485 parts by weight of methyl methacrylate (MMA),
An acrylic copolymer emulsion was obtained in the same manner as in Reference Example 1 except that 325 parts by weight of MA and 160 parts by weight of iso-butyl methacrylate (iBMA) or 335 parts by weight of MMA and 150 parts by weight of acrylonitrile (AN) were used. Table 1 shows the monomer composition, solid content, pH, viscosity, particle size, and Tg of the copolymer particles obtained during the polymerization.

Reference Example 9 A styrene-acrylic copolymer was prepared in the same manner as in Reference Example 1, except that 420 parts by weight of St and 65 parts by weight of 2-ethylhexyl acrylate (EHA) were used instead of using 485 parts by weight of St. A polymer emulsion was obtained. Table 1 shows the monomer composition, solid content, pH, viscosity, particle size, and Tg of the copolymer particles obtained during the polymerization.

Reference Examples 10 to 12 Styrene / acrylic copolymer emulsions were obtained in the same manner as in Reference Example 9 except that the ratio of St to EHA was changed. Monomer composition during this polymerization,
The solid content, pH, viscosity,
Table 1 shows the particle size and Tg of the copolymer.

Reference Example 13 An acrylic / styrene copolymer emulsion was obtained in the same manner as in Reference Example 1, except that St185 polymer and 300 parts by weight of iBMA were used instead of the St485 polymer. The monomer composition during this polymerization, the solid content of the obtained copolymer emulsion, p
Table 1 shows H, viscosity, particle size, and Tg of the copolymer.

Reference Examples 14 and 15 Styrene / acrylic copolymer emulsions having different particle diameters were obtained in substantially the same manner as in Reference Example 10 except that the amount of ABS used was changed. The monomer composition during the polymerization, the solid content, pH, viscosity, particle size, and T of the copolymer particles obtained in the obtained copolymer emulsion
g is shown in Table 1.

Reference Examples 16 and 17 In Reference Example 10, St360 parts by weight and EHA12
Instead of using 5 parts by weight, St340 parts by weight, EHA
120 parts by weight and 25 parts by weight of HEMA or St3
In the same manner as in Reference Example 10 except that 20 parts by weight, 115 parts by weight of EHA and 50 parts by weight of HEMA were used, styrene.
An acrylic copolymer emulsion was obtained. The monomer composition, the solid content, the pH, the viscosity, the particle size, and the Tg of the obtained copolymer emulsion during the polymerization are obtained.
Are shown in Table 1.

Reference Examples 18 to 19 In Reference Example 10, St360 parts by weight and EHA12
Instead of using 5 parts by weight, 370 parts by weight of St and 115 parts by weight of butyl acrylate (BA) or MMA3
A styrene-acrylic copolymer emulsion and an acrylic copolymer emulsion were obtained in the same manner as in Reference Example 10 except that 35% by weight and 150 parts by weight of HEMA were used. Table 1 shows the monomer composition, solid content, pH, viscosity, particle size, and Tg of the copolymer particles obtained during the polymerization.

[0142]

[Table 4]

Example 1 Commercially available SBR polymer emulsion SN-562 [manufactured by Sumitomo Dow Co., Ltd., Tg-40 ° C., viscosity 170 cps, pH
7.1, solids content 52.5% by weight, particle size 0.16μ] 13
3 parts by weight (about 70 parts by weight of solid content), 60 parts by weight of the styrene copolymer emulsion of Reference Example 1 (about 30 parts by weight of solid content), and Nopcopers 44C [manufactured by San Nopco Co., Ltd. Acid type] 2.0 parts by weight (solid content: about 0.88 parts by weight), as an inorganic filler, powdered calcium carbonate [SL-700, average particle size 4.5 µ, manufactured by Takehara Chemical Industry Co., Ltd.] 218 parts by weight , 3 parts by weight of carbon black and 12 parts by weight of barium metaborate are uniformly dispersed using a disperser, and then 0.5 part by weight of ADECANOL UH-472 (manufactured by Asahi Denka Co., Ltd.) as a thickener is added, followed by further stirring. Then, the ratio of the total pigment (total amount of powdered calcium carbonate, carbon black and barium metaborate) (hereinafter abbreviated as PWC) in the coating film is 70% by weight and the solid content is 70% by weight. 8 created a weight percent of chipping-resistant aqueous coating composition.

Various physical property tests were performed using the obtained aqueous coating composition. Table 2 shows the composition of the composition and the measurement results of various physical properties. The substrate of the test piece was Nippon Steel Corporation whose surface was cleaned with thinner.
Steel sheet, or a steel sheet (ED board) electrodeposited using a cationic electrodeposition paint “U-600” manufactured by Nippon Paint Co., Ltd., and the coating film is formed using a hot air circulation dryer. A high temperature baking treatment (preliminary drying at 80 ° C. for 15 minutes, followed by baking at 120 ° C. for 20 minutes) was performed.

Examples 2-3 and Comparative Examples 1-2 In Example 1, the SBR polymer emulsion SN-
Example 5 except that the use ratio of 562 and the styrene copolymer emulsion of Reference Example 1 was changed, or that only the SBR polymer emulsion SN-562 was used and the styrene copolymer emulsion of Reference Example 1 was not used. In the same manner as in Example 1, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Various physical property tests were performed using the obtained aqueous coating composition. Table 2 shows the composition of the composition and the measurement results of various physical properties. In addition, as the base material of the test piece, the same tan sheet steel plate as used in Example 1 was used,
The coating film was subjected to high-temperature baking in the same manner as in Example 1.

Examples 4 to 5 In the same manner as in Example 1 except that the amount of SL-700 used was changed, compositions for a chipping-resistant aqueous coating having different PWC were prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 2 and various physical property tests were performed. Table 2 shows the composition of the composition and the measurement results of various physical properties.

Examples 6 to 14 In Example 1, the SBR polymer latex SN-5 was used.
Instead of using S62, SBR polymer latex S
N-534, J-1666 [all manufactured by Sumitomo Dow Co., Ltd.],
SK-80 [manufactured by Takeda Pharmaceutical Co., Ltd.], L-2001, L
-2337 [manufactured by Asahi Kasei Kogyo Co., Ltd.], Polyrac 707 [manufactured by Mitsui Toatsu Chemicals, Inc.], LX-407C [manufactured by Zeon Corporation], or NBR-based polymer latex Nipol 1571, Nipol Using 1551 (all manufactured by Nippon Zeon Co., Ltd.), a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 1.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 2 and various physical property tests were performed. Table 2 shows the composition of the composition and the measurement results of various physical properties.

Examples 15 to 23 The same procedures as in Example 1 were carried out except that the copolymer emulsions of Reference Examples 2 to 9 or 13 were used instead of the styrene copolymer emulsion of Reference Example 1. In substantially the same manner, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 2, and various physical property tests were performed. Table 2 shows the composition of the composition and the measurement results of various physical properties. In addition, about Examples 17-18, Example 1
In the same manner as above, a tan sheet steel plate or E
A high temperature baking treatment was similarly performed using a D plate.

[0153]

[Table 5]

[0154]

[Table 6]

[0155]

[Table 7]

[0156] In Example 24-25 Example 1, SU-125 F as further crosslinking agent
[Aziridine compound manufactured by Meisei Chemical Industry Co., Ltd.] PWC was 70% by weight in substantially the same manner as in Example 1 except that 4 parts by weight (about 1 part by weight of solid content) or 2 parts by weight of zinc oxide was used.
Was prepared.

Various physical properties tests were performed using the obtained aqueous coating composition. Table 3 shows the composition of the composition and the measurement results of various physical properties. The same ED plate as that used in Example 1 was used as the base material of the test piece, and the coating film was subjected to high-temperature baking treatment in the same manner as in Example 1.

Examples 26 to 27 Example 24 or Example 25 was repeated, except that the styrene copolymer emulsion of Reference Example 5 was used instead of the styrene copolymer emulsion of Reference Example 1. In substantially the same manner as in Example 25, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Example 28 The procedure of Example 1 was repeated except that the SBR polymer emulsion SN-
Instead of using 133 parts by weight of 562 (about 70 parts by weight of solid content) and 60 parts by weight of the styrene-based copolymer emulsion of Reference Example 1 (about 30 parts by weight of solid content), SBR-based polymer emulsion SN-562 114 Parts by weight (about 60 parts by weight of solid content), 60 parts by weight of the styrene copolymer emulsion of Reference Example 1 (about 30 parts by weight of solid content) and a commercially available urethane resin emulsion M-589 [Toyo Polymer Co., Ltd.] Manufactured by the same method as in Example 1 except that 33 parts by weight (about 10 parts by weight in terms of solid content) were used.
Of 70% by weight of a chipping-resistant aqueous coating composition.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Examples 29 to 35 and Comparative Examples 3 and 4 In Example 28, the SBR polymer latex SN-
562, the use ratio of the copolymer emulsion of Reference Example 1 and the urethane resin emulsion M-589 was changed, or the copolymer emulsion of Reference Example 1 or the copolymer emulsion of Reference Example 1 and the urethane resin emulsion M-589 were used. A chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 28 except that 589 was not used.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Examples 36 to 37 Chipping resistant aqueous coating compositions having different PWCs were prepared in substantially the same manner as in Example 28 except that the amount of SL-700 used was changed.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Examples 38 to 46 In Example 28, the SBR polymer latex SN-
Instead of using 562, SBR-based polymer latex SN-534, J-1666, SK-80, L-2001,
Example 2 except that L-2337, Polylac 707, LX-407C, or NBR-based polymer latex Nipol 1571 or Nipol 1551 were used, respectively.
In substantially the same manner as in Example 8, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Examples 47 to 55 Example 2 was repeated except that the copolymer emulsion of Reference Example 2 to 9 or Reference Example 13 was used instead of the styrene copolymer emulsion of Reference Example 1.
In substantially the same manner as in Example 8, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Example 56 In Example 28, the urethane resin emulsion M-
A chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 28 except that urethane resin emulsion M-437 [manufactured by Toyo Polymer Co., Ltd.] was used instead of 589. did.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

Examples 57 to 60 Example 28 or Example 50 was repeated except that 4 parts by weight of SU-125 F (about 1 part by weight of solid content) or 2 parts by weight of zinc oxide were used as the crosslinking agent. In substantially the same manner as in Example 50, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 24, and various physical property tests were performed.
Table 3 shows the composition of the composition and the measurement results of various physical properties.

[0174]

[Table 8]

[0175]

[Table 9]

[0176]

[Table 10]

[0177]

[Table 11]

[0178]

[Table 12]

[0179]

[Table 13]

Example 61 The procedure of Example 1 was repeated, except that, instead of using the styrene copolymer emulsion of Reference Example 1, the styrene-acrylic copolymer emulsion of Reference Example 10 was used. PWC is 70% by weight and solid content is 78.
A 0% by weight chipping resistant aqueous coating composition was prepared.

Various physical property tests were performed using the obtained aqueous coating composition. Table 4 shows the composition of the composition and the measurement results of various physical properties. In addition, as in Example 1, a tan sheet steel plate or an ED plate was used as the base material of the test piece, and the coating film was subjected to a low-temperature baking treatment (baking at 80 ° C. for 30 minutes) using a hot-air circulation dryer. Was.

Examples 62 to 63 and Comparative Examples 5 to 6 In Example 61, the SBR polymer emulsion SN
The use ratio of the styrene-acrylic copolymer emulsion of Example-562 and the styrene-acrylic copolymer emulsion of Reference Example 10 was changed, or only the SBR-based polymer emulsion SN-562 was used.
In the same manner as in Example 61 except that the styrene-acrylic copolymer emulsion was not used, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Various physical property tests were performed using the obtained aqueous coating composition. Table 4 shows the composition of the composition and the measurement results of various physical properties. In addition, as the base material of the test piece, the same tan sheet steel plate as used in Example 1 was used,
The coating film was subjected to a low-temperature baking treatment in the same manner as in Example 61.

Examples 64 to 65 In the same manner as in Example 61 except that the amount of SL-700 used was changed, a chipping-resistant aqueous coating composition having a different PWC was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 62, and various physical property tests were performed.
Table 4 shows the composition of the composition and the measurement results of various physical properties.

Examples 66 to 74 The procedure of Example 61 was repeated except that the SBR polymer latex SN-
Instead of using 562, SBR-based polymer latex SN-534, J-1666, SK-80, L-2001,
Using L-2337, Polylac 707, LX-407C, or NBR-based polymer latex Nipol 1571 and Nipol 1551, respectively, in the same manner as in Example 61, a composition for a chipping-resistant aqueous coating having a PWC of 70% by weight. Created things.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 62, and various physical property tests were performed.
Table 4 shows the composition of the composition and the measurement results of various physical properties.

Examples 75 to 81 and Comparative Example 7 In Example 61, instead of using the styrene / acrylic copolymer emulsion of Reference Example 10, reference Example 11 was used.
A chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 61 except that the copolymer emulsions of Comparative Examples 14 to 19 or Reference Examples 14 to 19 were used.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 62, and various physical property tests were performed.
Table 4 shows the composition of the composition and the measurement results of various physical properties. In addition, about Examples 78-79, similarly to Example 61, the low temperature baking process was performed similarly using the tan sheet steel plate or the ED plate as a base material of a test piece.

[0190]

[Table 14]

[0191]

[Table 15]

[0192]

[Table 16]

Examples 82 to 83 The same procedures as in Example 57 or 58 were repeated except that the styrene-based copolymer emulsion of Reference Example 17 was used instead of the styrene-based copolymer emulsion of Reference Example 1. A chipping resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 57 or Example 58.

Various physical property tests were performed using the obtained aqueous coating composition. Table 5 shows the composition of the composition and the measurement results of various physical properties. The same ED plate as that used in Example 1 was used as the base material of the test piece, and the coating film was subjected to low-temperature baking treatment in the same manner as in Example 61.

Example 84 The procedure of Example 61 was repeated except that the SBR polymer emulsion SN was used.
Instead of using 133 parts by weight (about 70 parts by weight of solid content) and 60 parts by weight of the styrene / acrylic copolymer emulsion of Reference Example 10 (about 30 parts by weight of solid content), SBR polymer emulsion SN -562 95
Parts by weight (about 50 parts by weight of solid content), 40 parts by weight of the styrene / acrylic copolymer emulsion of Reference Example 10 (about 20 parts by weight of solid content), and 100 parts by weight of a commercially available urethane resin emulsion M-589 ( PW was obtained in substantially the same manner as in Example 61 except that about 30 parts by weight of solid content was used.
A chipping-resistant aqueous coating composition containing 70% by weight of C was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed.
Table 5 shows the composition of the composition and the measurement results of various physical properties.

Examples 85-88 and Comparative Examples 8-9 In Example 84, the SBR polymer latex SN-
562, Styrene / acrylic copolymer emulsion and urethane resin emulsion M-589 of Reference Example 10
Or the copolymer emulsion of Reference Example 10 or the copolymer emulsion of Reference Example 10 and the urethane resin emulsion M-589 were not used, except that the PWC was 70%. weight%
Was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed.
Table 5 shows the composition of the composition and the measurement results of various physical properties.

Examples 87 to 88 In the same manner as in Example 84 except that the amount of SL-700 used was changed, chipping-resistant aqueous coating compositions having different PWCs were prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed.
Table 5 shows the composition of the composition and the measurement results of various physical properties.

Examples 89 to 97 In Example 84, the SBR polymer latex SN-
Instead of using 562, SBR-based polymer latex SN-534, J-1666, SK-80, L-2001,
Example 8 except that L-2337, Polyrac 707, LX-407C, or NBR-based polymer latex Nipol 1571 or Nipol 1551 were used, respectively.
In substantially the same manner as in Example 4, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed.
Table 5 shows the composition of the composition and the measurement results of various physical properties.

Examples 98 to 104 In Example 84, instead of using the styrene / acrylic copolymer emulsion of Reference Example 10, reference Example 11 was used.
A chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 84 except that the copolymer emulsions of Comparative Examples 14 to 19 or Reference Examples 14 to 19 were used.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed.
Table 5 shows the composition of the composition and the measurement results of various physical properties.

Example 105 In Example 84, the urethane resin emulsion M-
A chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared in substantially the same manner as in Example 84 except that urethane resin emulsion M-437 was used instead of 589. Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed. Table 5 shows the composition of the composition and the measurement results of various physical properties.

[0206] In Example 106-109 Example 84 or Example 102, further SU-125 F 4 parts by weight as a cross-linking agent (solid content of about 1 part by weight) or except for using zinc oxide, 2 parts by weight Example 84 or In substantially the same manner as in Example 102, a chipping-resistant aqueous coating composition having a PWC of 70% by weight was prepared.

Using the obtained aqueous coating composition, test pieces were prepared in the same manner as in Example 82, and various physical property tests were performed.
Table 5 shows the composition of the composition and the measurement results of various physical properties.

[0208]

[Table 17]

[0209]

[Table 18]

[0210]

[Table 19]

[0211]

[Table 20]

The properties of the synthetic rubber latex and urethane resin emulsion used in Examples and Comparative Examples are shown in Tables 6 and 7, respectively.

[0213]

[Table 21]

[0214]

[Table 22]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09D 133/04 C09D 133/04 135/00 135/00 175/04 175/04 (72) Inventor Ryo Kume Isogo, Yokohama-shi, Kanagawa Yokodai Ward 3-24-26 Japan Carbide Industry Co., Ltd. Yokohama Dormitory (56) References JP-A-63-304062 (JP, A) JP-A-58-187468 (JP, A) JP-A-57-141460 (JP, A) A) JP-A-63-68677 (JP, A) JP-A-62-11779 (JP, A) JP-A-57-119945 (JP, A) JP-A-3-227496 (JP, A) JP-A Sho 52 JP-A-62-117898 (JP, A) JP-A-52-38547 (JP, A) JP-A-53-128642 (JP, A) JP-A-55-60566 (JP, A) JP-A-57-14656 (JP, A) JP-A-53-144951 (JP, A) JP-A-51-76343 (JP, A) JP-A-61-171776 (JP, A) JP-B-48-2924 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 109/00 C09D 109/10 C09D 5/00 C09D 5/02 C09D 125/00 C09D 133/04 C09D 135/00 C09D 175/04

Claims (2)

(57) [Claims] 1. An aqueous coating composition comprising polymer fine particles dispersed in an aqueous medium and an inorganic filler, wherein the polymer fine particles are separately obtained by emulsion polymerization. ) 50-95% by weight of synthetic rubber emulsion polymer particles containing 30-90% by weight of a conjugated diolefin unit and having a glass transition temperature of 0 ° C. or less; In the formula, R ¹ represents a hydrogen atom or a methyl group, Q represents —COOR ² , Or represents -CN, wherein R ² represents a lower alkyl group, R ³ is a glass transition temperature of at least 30 ° C. containing represents a hydrogen atom or a lower alkyl group, in the units represented 30 to 99.9 wt% And the average particle size is 0.0
5 to 0.5 micron emulsion polymer particles 5 to 50
A chipping-resistant aqueous coating composition, which is a mixture by weight. 2. The polymer fine particles further comprise (C) urethane emulsion polymer particles in an amount of 3 to 3 based on the total amount of emulsion polymer particles (A) and (B).
The aqueous coating composition according to claim 1, comprising 100% by weight.