JPH0454707B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a baking paint composition.
In more detail, it does not cause blistering or cracking when dried at temperatures above room temperature after being applied to a substrate such as a steel plate or ceramic, and its adhesion to the substrate after drying, the durability of the coating film, and its water resistance. The present invention relates to a method for producing a baking paint composition with excellent properties. Recently, there has been an active transition from solvent-based paints to water-based paints due to strict regulations on solvent emissions, improvements in paint application operations, and safety considerations. For example, chipping paint is applied to the lower part of the fender, the front end, or the lower part of the fuel tank to prevent damage caused by stones or rust while the car body is in motion. The switch from solvent-based paints to water-based paints is rapidly progressing. Furthermore, with the recent individualization of residential buildings, roof tiles have come to be coated with colored paints, and water-based baking paints are also used here. However, baking paints containing known aqueous polymer dispersions tend to produce blister or crevasse-like cracks during the drying (baking) process after being applied to the substrate, and also exhibit insufficient adhesion to the substrate after being made into a product. Due to these drawbacks, water-based baking paints are no longer available on the market. It had not yet become common. Until now, aqueous polymer dispersions have been applied to general paints using a multi-stage reaction method, but these paint films are difficult to apply because the polymer composition within the polymer particles is extremely non-uniform. It lacks resistance in terms of shock absorption, and has poor workability during seizure due to blistering. In addition, the properties required as a paint were also insufficient. In the so-called seed emulsion polymerization method, in which monomers are added to seed latex to prevent the formation of new particles, the seed polymer has specific properties, that is, the monomer composition is (a) ethylene. (b) conjugated diolefin 10-75% by weight, the balance being (c) aromatic vinyl monomer and (meth)acrylic acid ester having an alkyl group having 1 to 10 carbon atoms. A monomer mixture containing at least one monomer selected from Emulsion polymerization of the resulting polymer
(A) Take 0.1 to 10 parts by weight of the aqueous dispersion as a solid content and charge it in advance, and add (a) 0.5 to 15% by weight of an ethylenically unsaturated carboxylic acid and (d) a non-ethylenically unsaturated carboxylic acid. At least one monomer selected from copolymerizable monoethylenic monomers and conjugated diolefins is added in a proportion (d) such that the glass transition temperature of the resulting polymer is -60 to 30°C. Batchwise, sequentially or continuously, 100 parts by weight of the selected monomer mixture is added for emulsion polymerization, and the filler is added to the resulting aqueous dispersion of polymer (B) based on 100% by weight of the solid content. It has been found that a baking paint composition containing 50 to 1000 parts by weight solves the above-mentioned drawbacks. The present invention will be explained in detail below. (a) used in the first and second stages of emulsion polymerization;
Examples of ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid. Usage amount is 0.5-15
% by weight, particularly preferably 1 to 6% by weight.
If the amount used is less than 0.5% by weight, the manufacturing stability of the latex will be poor, coagulation will occur, and the mechanical stability of the paint will be poor, resulting in mechanical shearing force during paint formulation. Moreover, if it exceeds 15% by weight, the water resistance of the coating film will be poor. The conjugated diolefin (b) used in the present invention is a conjugated diolefin having 4 to 6 carbon atoms, specifically 1,3-butadiene, 2-methyl-1,3
-butadiene and its derivatives, 2-chloro-
Examples include 1,3-butadiene. The amount used is 10 to 75% by weight. If it is less than 10% by weight, the durability of the coating film will be poor, and if it exceeds 75% by weight, the final polymer will flow easily due to heat and will cause blisters during the baking process after paint application. becomes more likely to occur. Examples of aromatic vinyl monomers include styrene, p-methylstyrene, α-methylstyrene, chlorostyrene, etc., and examples of (meth)acrylic acid esters having an alkyl group having 1 to 10 carbon atoms include methyl acrylate and methacrylic acid. Methyl, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, acrylic acid n
-butyl, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, amyl acrylate, amyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, acrylic acid 2-
Examples include ethylhexyl, 2-ethylhexyl methacrylate, octyl acrylate, isononyl acrylate, and decyl acrylate. The amount of aromatic vinyl monomer and/or (meth)acrylic acid ester (c) to be used will be determined once (a) and (b) are determined, but the amount of the seed polymer used in the subsequent polymerization will be determined. Even when the amount is small, the hardness (glass transition temperature) of the seed polymer (A) affects the toughness of the final polymer (B), so these monomers are
The amount and combination of (B) to be used should be selected so that the glass transition temperature of (B) is -60 to 30°C. Particularly preferred combinations of monomers from these include acrylic acid, methacrylic acid, and itaconic acid as ethylenically unsaturated carboxylic acids, 1,3-butadiene as conjugated diolefin, and styrene and (meth)acrylic acid esters as aromatic vinyl monomers. It is appropriately selected from n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, diethylamino (meth)acrylate, and dimethylaminoethyl (meth)acrylate. In addition, copolymerizable monoethylenically monomers other than ethylenically unsaturated carboxylic acids used in the subsequent emulsion polymerization include acrylonitrile, vinyl acetate, acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, β-hydroxyethyl acrylate,
Examples include β-hydroxyethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, vinyl chloride, and vinylidene chloride. The aqueous polymer (A) dispersion of these seeds is subjected to conventional emulsion polymerization. For example, per 100 parts by weight of the monomer, 65 to 200 parts by weight of water, 0.05 to 5.0 parts by weight of an emulsifier, 0.1 to 2.0 parts by weight of a polymerization initiator, 0.05 to 5.0 parts by weight of a chain transfer agent, and in some cases a chelating agent. , PH adjuster,
It is obtained by reacting with an electrolyte at 40°C to 90°C for 8 to 30 hours. It is preferable from the viewpoint of storage stability that the obtained aqueous polymer (A) dispersion is adjusted to pH 7 with an aqueous alkaline solution. Here, anionic, nonionic,
Anionic-nonionic combinations, amphoteric surfactants are used as appropriate. Examples of anionic surfactants include sodium salts of higher alcohol sulfates, sodium alkylbenzenesulfonates, sodium succinic acid dialkyl estersulfonates, and sodium alkylnaphthalenesulfonates, and polyoxyethylene as nonionic emulsifiers. Examples include alkyl ethers and polyoxyethylene alkyl phenol ethers, and examples of amphoteric surfactants include alkylpetaines and amine oxides. These emulsifiers are used in an amount of generally 0.05 to 5.0 parts by weight, particularly preferably 0.1 to 4.5 parts by weight, in order to control the average particle diameter of the aqueous polymer (A) dispersion to the required 0.05 to 0.5 μm. The average particle diameter of the aqueous polymer (A) dispersion liquid serving as a seed is preferably 0.05 to 0.3 μm, particularly preferably 0.1 to 0.25 μm.
If it is less than 0.05 μm, not only will the final polymer (B) dispersion obtained have a high viscosity, but also cracks will occur when the paint dries. If the average particle diameter exceeds 0.5 μm, the water resistance of the painted film after baking will be poor. As the polymerization initiator, water-soluble initiators are preferred, and examples include persulfates (for example, ammonium persulfate, potassium persulfate, sodium persulfate), hydrogen peroxide, cerium nitrate, etc. In some cases, a reducing agent may also be used in combination. can. Chain transfer agents include halogenated carbons (e.g. aromatic tetrachloride, chloroform, bromoform), mercaptans (n-dodecylmercaptan, t-
dodecyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-stearyl mercaptan), and xanthogens (eg, dimethyl xanthogen disulfide, diisopropyl xanthogen disulfide). These chain transfer agents are aqueous polymers (A) that serve as seeds.
Adjust the solubility of in toluene. Polymer (A)
The insoluble content in toluene must be 90% by weight or less; however, if it exceeds 90% by weight, the adhesion to the substrate will be poor, and when the coating is exposed to high humidity, it will peel or protrude from the interface between the substrate and the coating. This causes blistering and prevents rust, which is the original purpose of the paint. Here, what is the toluene-insoluble portion of the polymer? After adjusting the pH of the aqueous polymer dispersion to 7 with an aqueous ammonia solution, it was coated on a glass plate in a dry state to a thickness of 0.5 mm, and heated at 50°C. Leave it for 6 hours under constant temperature and humidity at 50% RH. Next, take out the dry film, weigh out 0.3g accurately, and immerse it in 100g of toluene for 24 hours. After this, it was wrapped in a wire mesh for 200 meshes,
The insoluble content of the polymer in toluene is calculated from the solid content contained in the liquid. The insoluble content of the polymer in toluene is particularly preferably 85% or less. The aqueous polymerization (A) dispersion obtained above is present in an amount of 0.1 to 10 parts by weight in terms of solid content to finally obtain a dispersion for baking paint. At this time, water is added to the aqueous polymer (A) dispersion.
Adding 70 to 180 parts by weight, 0.1 to 1.0 parts by weight of a polymerization initiator, and 0 to 2.0 parts by weight of an emulsifier, the monomer mixture consisting of (a) and (b) can be added batchwise, sequentially, or continuously. preferable. In particular, it is preferable to add the emulsifier in a minimum amount that does not generate new particles, in accordance with the amount of the monomer mixture added. The amount of the aqueous polymer (A) dispersion present is 0.1 to 10 parts by weight, particularly preferably 0.3 to 5.0 parts by weight, in terms of solid content. More preferably, it is 0.5 to 3.0 parts by weight. If it is less than 0.1 part by weight, the particle size of the aqueous polymer (B) dispersion becomes large and the water resistance of the coating film becomes poor. If it exceeds 10 parts by weight, the blister resistance of the paint during baking and the durability of the paint film will deteriorate. The average particle diameter of the aqueous polymer (B) dispersion is 0.12~
0.5 μm is preferred, particularly preferably 0.15 to 0.25 μm
It is. If the average particle size is less than 0.12 μm, cracks or blisters will occur in the dried coating film, and if it exceeds 0.5 μm, water resistance will be poor. Furthermore, the aqueous polymer (B) dispersion is prepared by the above-mentioned method so that the insoluble content of the polymer in toluene is preferably 20 to 95% by weight, particularly
30-90% by weight is preferred. Further, the glass transition temperature of the polymer (B) is preferably -60 to 30°C, particularly preferably -50 to 20°C. If the glass transition temperature is lower than -60°C, the paint film will have poor baking properties, chipping resistance, and solvent resistance, and if it is higher than 30°C, the film forming properties of the paint will be undesirable. The aqueous polymer (B) dispersion obtained according to the present invention contains fillers, dispersants (sodium polyacrylate, ammonium polyacrylate, sodium hexametaphosphate, potassium pyrophosphate), thickeners (for example, hydroxyethyl cellulose, high molecular weight sodium polyacrylate), plasticizers (e.g. DOP,
DBP, epoxidized fatty acid ester), auxiliary agent (n-
Propyl alcohol, ethyl cellosolve, carbitol, ethylene glycol, diethylene glycol), curing agent (melamine-formalin resin,
Glyoxal resins, epoxy compounds, inorganic metal complexes, aziridine compounds), leveling agents (for example, rosin-modified polyester resins, styrene-maleic anhydride copolymer resins), etc. may be combined to create the desired formulation for the paint. The materials used as fillers include calcium carbonate, clay, carbon black, zinc oxide, asbestos, glass fiber, titanium oxide, and dolomite, and the amount used is based on 100 parts by weight of the solid content of the polymer (B). Preferably 50 to 1000 parts by weight, more preferably
50 to 500 parts by weight, particularly preferably 50 to 300 parts by weight. If the amount used is less than 50 parts by weight, the baking property of the paint
It has poor chipping resistance and requires a large amount of polymer, which increases costs. Furthermore, if the amount used exceeds 1000 parts by weight, the stability of the paint will decrease and the film forming properties will also be poor. Furthermore, the aqueous polymer (B) dispersion may be mixed with other water-soluble or aqueous polymer dispersions (e.g. polyethylene, ethylene/vinyl acetate copolymer, polyvinyl chloride,
Polyvinylidene chloride) may be mixed with the polyvinylidene chloride to the extent that the properties of the present invention are not impaired. The coating composition of the present invention is used as a substrate for baking steel plates, cement plates, and ceramic plates. Application can be done using a roller coater, air spray, curtain flow coater, overflow coater,
Application methods include airless spraying and brushing. Furthermore, alkyd resin paints, acrylic resin paints, epoxy resin paints, and melamine resin paints may be used as undercoats or top coats for paints using the paint composition of the present invention. The present invention will be explained in more detail below with reference to Examples and Comparative Examples. In each example, parts or percentages are based on weight. Examples 1 to 4, 7 150 parts of distilled water, 25 parts of 1,3-butadiene,
55 parts of styrene, 18 parts of methyl methacrylate, 2 parts of methacrylic acid, potassium persulfate as a polymerization initiator
0.5 parts, 0.3 parts of t-dodecyl mercaptan as a chain transfer agent, sodium alkyl diphenyl ether disulfonate (Newcol) as an emulsifier.
271A (Nippon Nyukazai Co., Ltd.) and 0.2 parts of potassium carbonate as a PH adjuster were added and reacted at a reaction temperature of 45°C for 15 hours, and further reacted at 55°C for 10 hours. Next, the pH was adjusted to 6 with aqueous ammonia, steam was passed under reduced pressure to remove unreacted monomers, the pH was adjusted to 7 again with aqueous ammonia, and the mixture was filtered through a 180 mesh cloth. The average particle size of the obtained aqueous polymer (A) dispersion was
0.12 μm (measured by Nanosizer; used by Coulter) The insoluble content in toluene was 50%. Next, in the presence of 2.0 parts of aqueous polymer (A) dispersion adjusted to pH 7 in terms of solid content, 100 parts of water and 0.3 parts of potassium persulfate as a polymerization initiator were added to a cooler, a stirrer, a thermometer, and a monomer. The mixture was placed in a flask reactor equipped with a pump, and the temperature was raised to 70°C using a heater.
At this time, from a separate container, 65 parts of n-butyl acrylate, 27 parts of methyl methacrylate, 5 parts of acrylonitrile,
A monomer mixture of 3 parts of methacrylic acid was added continuously over a period of 3 hours. After the addition of the mixed monomers was completed, the mixture was further aged for 3 hours, cooled, and then adjusted to pH 7 with an aqueous ammonia solution. It was then washed with 80 mesh cloth. The average particle size of the resulting polymer (B) dispersion was 0.18 μm. Next, 100 parts (solid content equivalent) of the obtained aqueous polymer (B) dispersion, 250 parts of calcium carbonate (Super SS; Maruo Calcium Co., Ltd.) and 50 parts of clay (K clay; Katsumitsuyama Mining Co., Ltd.) as fillers, SN- as a dispersant
Dispersant 5044 (Nopco) 2.0 parts, ethylene glycol 1.0 parts, hydroxyethyl cellulose (A-5000; Fuji Chemical) 0.2 parts as a thickener,
Preservative (Nopco) SN-215, 0.05 part, antifoaming agent (Nopco) Foamas-ter AP 0.5 part, 2-amino-2-methyl-1-propanol 2.0 parts, zinc oxide 1.0 part, zinc chromate 0.5 part, carbon black
After adding 1.0 part of hydroxyethyl cellulose (A-500; Fuji Chemical Co., Ltd.) as a thickener and adjusting the solid content to 75% with water, the viscosity of the paint was adjusted.
Adjusted to 10000cps (BH type viscometer).
The mixture was sufficiently mixed using a disper stirrer and then transferred to a vacuum degassing machine for defoaming. The obtained paint was cleaned with xylene and an alkaline detergent on an iron plate (JIS-G3141 SPCCD, 0.8
×70×150〓) using an airless sprayer so that the film thickness after drying was 800 μm. The coated iron plate was dried at 130°C for 30 minutes. However, the blister resistance and cracking resistance were tested under different conditions. The coated plates were subjected to the following tests. (1) Blister resistance: The presence or absence of blisters in the paint film after drying was determined visually. condition is
It was carried out at 130°C for 30 minutes and at 150°C for 20 minutes. 〇; No blisters occur △; 1 to 10 blisters on the paint film ×; Blisters occur on the entire surface (2) Cracking resistance; The thickness of the paint film is 800μm and
It was coated to a thickness of 1000 μm and the condition of the coated surface was visually judged. (Drying conditions 130℃, 30
minute) 〇; No cracking △; Fine cracks on the paint film surface ×; “Cracks” occurred on the entire surface of the paint film (3) Adhesion; Judging the condition when the adhesive tape was peeled off after cross-cutting the paint film surface ( 2mm square 10
×10 pieces) 〇; Number of remaining pieces on the cut painted surface 100-90 △; 〃 89-50 was determined. (The paint film thickness is
800μm) 〇; No change at all △; Paint film softened ×; Peeling or blistering occurred (5) Durability: A nut (M-6 ) was continuously dropped, and the weight when the substrate was exposed was evaluated. (Paint film thickness is 800μm
○; 50Kg or more △; 49-30Kg ×; 29Kg or less (6) Mechanical stability of paint; Maron test method Paint 100
The g conditions are the percentage of coagulated matter after passing through 80 meshes in the paint after high-speed shearing at 1000 rpm for 5 minutes under a load of 10 kg. (7) Corrosion resistance: Salt spray test according to JIS-Z2371
The condition of the iron plate after 500 hours was judged visually. (Paint film thickness is 800 μm) ○: Rust occurred within 1 mm from the cross-cut line △: Less than 3 mm ×: 2 mm or more The test results are shown in Table 1. As is clear from the results, the test results of the coating film were excellent. Similarly, Examples 2, 3, 4, and 7 of Table 1
is an example using an aqueous polymer dispersion in which the monomer composition of polymer (A), the amount of t-dodecyl mercaptan in polymer (A), and the charged amount of polymer (A) were varied, respectively.
The object of the present invention has been obtained. Example 5 As in Example 1, 150 parts of distilled water was placed in a pressure-resistant reaction vessel.
25 parts of 1,3-butadiene, 55 parts of styrene, 18 parts of methyl methacrylate, 2 parts of methacrylic acid, 0.5 part of potassium persulfate as a polymerization initiator, 0.3 part of t-dodecylmercaptan as a chain transfer agent, and sodium alkyl diphenyl as an emulsifier. 1.0 part of ether disulfonate, 0.6 potassium carbonate as PH regulator
of the mixture was added and reacted for 15 hours at a reaction temperature of 43℃, and then
The reaction was carried out at 55°C for 10 hours. Next, adjust the pH to 6 with ammonia water, remove unreacted monomers by passing steam under reduced pressure, and then adjust the pH to 7 with ammonia water again.
It was adjusted to 180 mm and passed through a 180 mesh cloth. The average particle size of the obtained aqueous polymer (A) dispersion was
At 0.20 μm, the insoluble content in toluene was 55%. Thereafter, the same reaction as in Example 1 was carried out to obtain an aqueous polymer (B). It is listed as Example 5 in Table 1, and the same paint formulation was implemented and the test was conducted. Example 6 As in Example 1, 250 parts of distilled water was placed in a pressure-resistant reaction vessel.
25 parts of 1,3-butadiene, 55 parts of styrene, 18 parts of methyl methacrylate, 2 parts of methacrylic acid, 0.3 part of potassium persulfate as a polymerization initiator, 0.3 part of t-dodecylmercaptan as a chain transfer agent, alkylbenzenesulfonic acid as an emulsifier. sodium salt
4.0 parts were added and the mixture was reacted for 20 hours at a reaction temperature of 50°C.
Next, the pH was adjusted to 6 with aqueous ammonia, water vapor was introduced under reduced pressure to remove unreacted monomers, the pH was adjusted to 7 again with aqueous ammonia, and the mixture was filtered through a 180 mesh cloth. The average particle size of the obtained aqueous polymer (A) was 0.08 μm, and the insoluble content in toluene was 60
It was %. Thereafter, the same reaction as in Example 1 was carried out to obtain an aqueous polymer (B). A test similar to Example 1 was conducted. It is listed as Example 6 in Table-1. Examples 1 to 7 Comparative Examples 1 to 7 were conducted in the same manner as in Example 1 to determine the composition of the polymer (A) (Comparative Examples 1 to 5) and the amount of the polymer (A) dispersion (Comparative Examples 6, 7) Change polymer (B)
A dispersion liquid was prepared and the same test as in the example was conducted using the same paint formulation. The results are shown in Table 2 as Comparative Examples 1 to 7. Comparative Example 8 150 parts of distilled water was placed in the same pressure-resistant reaction vessel as in Example 1.
25 parts of 1,3-butadiene, 55 parts of styrene, 18 parts of methyl methacrylate, 2 parts of methacrylic acid, 0.5 part of potassium persulfate as a polymerization initiator, 0.3 part of t-dodecylmercaptan as a chain transfer agent, and sodium alkyl diphenyl as an emulsifier. 0.5 parts of ether disulfonate, 1.0 part of potassium carbonate as a PH regulator
10 hours at a reaction temperature of 43℃ and 10 hours at a reaction temperature of 45℃.
The reaction was further carried out at 50°C for 10 hours. Next, the pH was adjusted to 6 with aqueous ammonia, steam was introduced under reduced pressure to remove unreacted monomers, the mixture was adjusted again with aqueous ammonia, and filtered through a 180 mesh cloth. The average particle size of the obtained aqueous polymer (A) dispersion was
At 0.35 μm, the insoluble portion of the polymer in toluene is
It was 45%. Next, as in Example 1, acrylic acid n was added from a separate container.
- A monomer mixture of 65 parts of butyl, 27 parts of methyl methacrylate, 5 parts of acrylonitrile, and 3 parts of methacrylic acid was reacted to obtain an aqueous polymer (B) dispersion. The average particle size of the resulting aqueous polymer (B) dispersion was 0.51 μm.
It was hot. The same physical property test was carried out using the same paint formulation as in Example 1, and this is shown in Table 2 as Comparative Example 8. Comparative Example 9 In a reaction vessel similar to Example 1, 250 parts of distilled water, 1,
25 parts of 3-butadiene, 55 parts of styrene, 18 parts of methyl methacrylate, 2 parts of methacrylic acid, 0.3 parts of potassium persulfate as a polymerization initiator, t as a chain transfer agent.
- 0.3 parts of dodecyl mercaptan, 6.0 parts of alkylbenzenesulfonate sodium salt as emulsifier
of the mixture was added, and the mixture was reacted for 20 hours at a reaction temperature of 50°C. Next, the pH was adjusted to 6 with ammonia water, steam was passed under reduced pressure to remove unreacted monomers, the pH was adjusted to 7 again with ammonia water, and the coagulated material was removed using a 180 mesh cloth. The average particle diameter of the obtained aqueous polymer (A) was 0.04 μm, and the insoluble content in toluene was 68%. Thereafter, the same monomer composition as in Example 1 (65 parts of n-butyl acrylate, 27 parts of methyl methacrylate, 5 parts of acrylonitrile, 3 parts of methacrylic acid) was polymerized to obtain a polymer (B) dispersion. The average particle diameter of the resulting polymer (B) dispersion was 0.11 μm. Example 1
Similar physical property tests were conducted using the same paint formulation as in Table 2. From the above, the baking paint composition of the present invention exhibits excellent performance, while Comparative Example 1, which has a polymer composition of the aqueous polymer (A) dispersion with a small amount of 1,3-butadiene, which is out of the technical scope of the present invention, has good performance. In Comparative Example 2, which had poor properties and conversely more properties, blisters occurred when the paint was drying. Furthermore, in Comparative Example 3, in which the amount of methacrylic acid in the polymer composition of the aqueous polymer (A) dispersion was small, the mechanical stability of the paint was extremely insufficient, and the workability of spraying onto the substrate was poor. Ta. In Comparative Example 4, which contained a large amount of methacrylic acid, the water resistance of the coating film was poor, and the corrosion resistance was also slightly poor. Comparative Example 5 in which the insoluble content in toluene of the aqueous polymer (A) dispersion exceeds 90%
However, the resulting coating film had poor adhesion to the substrate and poor corrosion resistance. In Comparative Example 6, in which the amount of water-based polymer (A) was small, the water resistance of the coating film was poor. Furthermore, in Comparative Example 7, which had a large amount of preparation, blisters were generated during drying of the coating film, and the durability was also poor. Furthermore, in Comparative Example 8, in which the average particle size of the aqueous polymer (B) dispersion obtained was large, the paint film had poor water resistance and corrosion resistance, and in Comparative Example 9, in which the average particle size was small, blistering occurred when the paint was baked on the substrate. occurs countless times,
Furthermore, when the paint film became thicker, severe cracking occurred, and the mechanical stability of the paint itself was also poor.

【table】

[Table] Examples 8 and 9 Using the polymer (A) of Example 1, polymer (B) was polymerized in the same manner as in Example 1 using the monomer composition of the post-polymerization shown in Table 3, and evaluated. . The monomer composition in the latter stage was within the scope of the present invention, and the desired performance of the present invention was obtained. Examples 10 and 11 Using the polymer (A) of Example 3, a polymer (B) was obtained using the monomer composition of the latter stage polymerization shown in Table 3. The polymerization method and evaluation were carried out in the same manner as in Example 3, but the results were in line with the objectives of the present invention. Comparative Examples 10 and 11 Comparative Example 10 is an example in which the amount of ethylenically unsaturated carboxylic acid in the post-polymerization is outside the range of the present invention. , the mechanical stability of the paint is poor. Moreover, Comparative Example 11 is a case beyond the scope of the present invention, and is inferior in water resistance, durability, and corrosion resistance. Comparative Examples 12 and 13 are examples in which the Tg of polymer (B) is outside the scope of the present invention,
Comparative Example 12 is a case where Tg is low beyond the range, and the blister resistance is poor. Furthermore, Comparative Example 13, which has a Tg exceeding the range, is inferior in cold water resistance and durability.

[Table] Comparative Example 14 For the first stage polymerization, 200 parts of water, 02 parts of potassium persulfate, and Table 4 were added to the reactor shown in Example 1.
60% by weight of the monomer mixture shown in 1 was charged and reacted for 1 hour at a reactor jacket temperature of 70°C. The polymerization conversion rate was 98%. For the second stage polymerization, 40% by weight of the remaining monomer mixture and 10 parts of an aqueous solution of 1% potassium persulfate were each added separately and continuously to the above reactor over a period of 3 hours, and after the addition was complete, an additional 3 Time aged.
The final polymerization conversion rate was 99%. The following is Example 1
In the same manner as above, unreacted monomers were removed and pH was adjusted to obtain a polymer dispersion. The same amount of the same additive as in Example 1 was added to 100 parts of the obtained polymer dispersion to prepare a baking paint. Using the obtained baking paint, each test was carried out in the same manner as in Example 1, and the obtained results are shown in Table 4. This example is a two-step polymerization method that is generally used for copolymer latex polymerization, but the amount of polymer particles produced in the first step polymerization is extremely large compared to the amount of seed polymer particles of the present invention. As a result, blister resistance, cracking resistance, adhesion, durability, and corrosion resistance are poor.

【table】

【table】

Claims (1)

[Claims] 1 (a) 0.5-15% by weight of ethylenically unsaturated carboxylic acid, (b) 10-75% by weight of conjugated diolefin, the balance being (c)
A monomer mixture containing at least one monomer selected from an aromatic vinyl monomer and a (meth)acrylic acid ester having an alkyl group having 1 to 10 carbon atoms is added to a latex with an average particle diameter of 0.05 to 10. 0.5μm,
Emulsion polymerization is performed so that the toluene insoluble content measured by the method defined in the text is 90% by weight or less, and the resulting aqueous dispersion of polymer (A) is 0.1 to 10% in solid content.
(a) 0.5 to 15% by weight of ethylenically unsaturated carboxylic acid, (d) copolymerizable monoethylenic monomer other than ethylenically unsaturated carboxylic acid and conjugated diolefin. 100 parts by weight of a monomer mixture in which the ratio of (d) is selected such that the glass transition temperature of the resulting polymer is -60 to 30°C is added batchwise to at least one monomer selected from ,
A baking paint composition prepared by adding 50 to 1000 parts by weight of a filler per 100 parts by weight of solids to the aqueous dispersion of polymer (B) obtained by emulsion polymerization by adding them sequentially or continuously. Production method.