JPS6254351B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aqueous coating composition that provides a coating film with excellent water resistance, adhesion, and gloss. Most coating compositions currently in use can be broadly classified into solvent-based and aqueous-based, and aqueous-based ones can be further subdivided into emulsion-type and water-soluble types. Conventionally, solvent-based products have mainly been used, but solvent-based products have many problems such as the risk of fire and explosion, the negative impact on occupational safety and health due to their toxicity, and air pollution. There is. On the other hand, conventional water-based products have less of these problems, but emulsion-based products contain a large amount of emulsifier, resulting in poor water resistance and adhesion of the coating, and it is difficult to obtain a glossy coating. It was difficult. In addition, the molecular weight of the resin in the water-soluble type is lower than that of the emulsion type, and the water resistance and weather resistance of the coating film are inferior.Furthermore, when the resin concentration in the system is increased, the viscosity of the system increases significantly, and the coating Since the work was extremely difficult, it was not easy to obtain a coating film with a feeling of longevity. As a result of extensive studies to solve these drawbacks, the present inventors have discovered the advantages of water-soluble coating compositions and emulsion-type coating compositions, namely, the solid content concentration of coating compositions. A composition that has high and moderate viscosity, and has excellent gloss, smoothness, and adhesion, as well as water resistance, is used as a polymeric dispersion stabilizer and is made from derivatives of acrylic acid or methacrylic acid. The inventors have discovered that this problem can be obtained by crosslinking an emulsion obtained by dispersing and polymerizing monomers in water with a hydrophilic epoxy compound to eliminate low-molecular-weight substances from the resin forming the coating film. That is, (A); a hydrophilic epoxy compound having two or more epoxy groups per molecule. (B): An emulsion obtained by polymerizing a monomer () consisting of at least one derivative of acrylic acid or methacrylic acid in water in the presence of a polymeric dispersion stabilizer consisting of the following (C). In some cases, the emulsion has a functional group that reacts with the epoxy group of (A). (C); A polymer dispersion stabilizer containing a lipophilic polymer part and a hydrophilic polymer part in the same molecule, where the hydrophilic polymer part is made of acrylic acid or methacrylic acid of (B). Polymer dispersion stabilizer with good compatibility with polymers made from monomers () consisting of derivatives. The above (A) and (B) are equivalent of the epoxy group in the epoxy compound of (A)/(B)
The aqueous coating composition has excellent water resistance, characterized in that the equivalent of the functional group that reacts with the epoxy group in the emulsion composition is blended in a ratio of 0.05 to 2.5.
The present invention was completed based on the discovery that a coating film having adhesive properties and gloss can be provided. The particles of the emulsion (B) of the present invention are polymers with extremely high molecular weights, which surround the inside and surroundings of the particles and prevent particle agglomeration.Compared to the polymer inside the particles, the polymer has a low molecular weight and is stable in dispersion. It consists of a drug part. This polymeric dispersion stabilizer has a relatively lipophilic polymer portion that is highly compatible with the polymer constituting the inside of the emulsion particles, so the molecules are entangled with the polymer inside the emulsion particles. It is firmly fixed inside the particles, forming an extremely stable emulsion. this
When only the emulsion (B) is made into a coating, the coating looks like a tiled floor. That is, the tile portion is a high molecular weight polymer inside the emulsion particles, and the binder portion is a polymeric dispersion stabilizer in the outer layer of the emulsion particles. This polymeric dispersion stabilizer has a large number of hydrophilic groups and has a relatively low molecular weight, so it has a high affinity for water, and is therefore the primary cause of negative effects on various physical properties such as water resistance of paint films. ing. In the present invention, by crosslinking this polymer dispersion stabilizer using a hydrophilic epoxy compound that reacts at a relatively low temperature, the molecular weight is substantially increased and the affinity for water is reduced. With this composition, a coating film exhibiting excellent water resistance and having various desirable properties can be obtained. (A) used in the present invention; as a hydrophilic compound having two or more epoxy groups per molecule, when 1 g of the compound is dissolved in 10 g of water, 50
Any polyepoxy compound may be used as long as it is soluble in water but substantially dispersed in water, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol poly These include, but are not limited to, compounds such as glycidyl ether, diglycerol polyglycidyl ether, polyglycerin polyglycidyl ether, sorbitol polyglycidyl ether, or ortho-cresol novolak type epoxy resin which is an aqueous dispersion. . The monomer () consisting of a derivative of acrylic acid or methacrylic acid used in the production of the emulsion (B) used in the present invention is an unsaturated monomer that can be obtained by ordinary radical polymerization. Any body can be used, such as the following: 1 General formula of acrylic acid or methacrylic acid derivatives

[Formula], R ₁ is hydrogen or a methyl group, R ₂ is a C _1-20 alkyl group, a C _5-6 cycloalkyl group, a methoxybutyl group, an ethoxybutyl group, a polyalkylene glycol residue , phenyl group, benzyl group, C _2-8 hydroxyalkyl group, glycidyl group, dicyclopentynyl group, -NH ₂ , -NHCH ₂ OH, -
_{NHCH2OC4H9 etc. _} It is sufficient to select and use at least one of these monomers () made of derivatives of acrylic acid or methacrylic acid.
No. 51-28188, Special Application No. 1983-3508, Special Application No. 1983-
The present invention includes the use of polymers such as cellulose derivatives in methods such as those presented in No. 93647. The polymeric dispersion stabilizer used as a dispersion stabilizer in the production of the emulsion (B) has a good compatibility with the polymer made from the monomer () consisting of a derivative of acrylic acid or methacrylic acid. A graft polymer or a block polymer in which the hydrophilic polymer portion and the hydrophilic polymer portion are bonded in the same molecule, and which has a functional group reactive with the epoxy group of (A). It is what you have. Here, the functional group reactive with the epoxy group (A) is, for example, a carboxyl group, an acid anhydride,
Carboxylic acid groups, alcoholic hydroxyl groups, phenolic hydroxyl groups, N-methylol groups, primary amino groups, secondary amino groups, tertiary amino groups, amide groups, sulfonic acid groups, mercaptan groups, urethane groups, etc. . Usually, these functional groups are often present in the hydrophilic polymer portion of the polymer dispersion stabilizer of the present invention, as will be described in detail later, and if they are not present, for example, a polymerizable polymer having the functional group In some cases, monomers are copolymerized when synthesizing a polymeric dispersion stabilizer, or acrylic acid or maleic anhydride is added to a polymer using a radical-generating compound such as benzoyl peroxide. The functional group may be introduced into the polymer dispersion stabilizer by such a method as described above. The molecular weight of the polymer dispersion stabilizer is 300 to 200,000, preferably 300 to 20,000, and the number average molecular weight of the polymer part is 300 to 200,000.
100,000, preferably 500 to 30,000.
Low molecular weight polymers with a number average molecular weight of less than 300 have little dispersion stabilizing effect, and
If it is larger than 100,000, the viscosity of the system becomes extremely high when used as a dispersion stabilizer, making it difficult to handle. Furthermore, it is important that the polymer portion has good compatibility with the oil-based substance, and especially when the oil-based substance is a radically polymerizable unsaturated monomer as in the present invention, the monomer is, of course, The dispersion stabilizer is immobilized on the dispersion particles by being compatible with the polymer formed therefrom, and the hydrophilic portion of the dispersion stabilizer, that is, the polymer portion, is in the aqueous phase and the dispersion particles coalesce. , is thought to prevent agglomeration. In order for this part of the polymer to have good compatibility with the polymer from the radically polymerizable unsaturated monomer () used in the preparation of the emulsion of (B), it is necessary to SP of both polymers
It is necessary that the (Solubility Parameter) value is within ±1.0, and preferably the compositions of both polymers are the same. Therefore, as monomers constituting the polymer portion, all monomers () consisting of derivatives of acrylic acid or methacrylic acid are suitable; The monomer () consisting of a derivative of acrylic acid or methacrylic acid may be selected and used so that the difference in SP value between the polymer and the polymer is within ±1.0, and preferably the monomer () consisting of a derivative of acrylic acid or methacrylic acid is completely the same. It is preferable to produce a polymeric portion of selected materials. Further, the polymer constituting the portion may be any hydrophilic polymer, and examples thereof include the following. (i) Water-soluble natural polymers For example, gelatin, alginic acid, alginates, starch paste, etc. (ii) Cellulose-modified water-soluble resin, such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, etc. (iii) Polyalkylene glycol and its derivatives, such as polyethylene glycol, polypropylene glycol, ethylene glycol propylene glycol copolymer, polyethylene glycol methacrylate monoester, and the like. (iv) Polymers from hydrophilic radically polymerizable unsaturated monomers For example, α,β-ethylenically unsaturated carboxylic acids (acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, acids), salts of α,β-ethylenically unsaturated carboxylic acids, styrene sulfonic acid, styrene sulfonates, vinyl sulfonic acid, (poly)alkylene glycol esters of acrylic acid or methacrylic acid, acrylic acid amide, methacrylic acid amide, vinyl pyridine,
A homopolymer or copolymer comprising at least one of N-vinyl-2-pyrrolidone, chloromethylstyrene/amine adduct, etc. (v) Copolymer of hydrophilic radically polymerizable unsaturated monomer and other radically polymerizable unsaturated monomer For example, at least one of the monomers constituting the polymer (iv) and A copolymer of a monomer other than the monomer and at least one radically polymerizable unsaturated monomer capable of radical copolymerization. (vi) Others Hydrolysates of vinyl acetate, acrylic esters, methacrylic esters, etc., or hydrolysates of copolymers consisting of vinyl acetate, acrylic esters, methacrylic esters, etc. and other monomers, anhydrous Maleic acid-modified polyethylene wax, etc. The method for producing the polymeric dispersion stabilizer used in producing the aqueous coating composition of the present invention is not particularly limited, but may be a method commonly known for obtaining a graft polymer or a block polymer, such as the method used by the Society of Polymer Science and Technology. Magazine "Komunshi" Vol. 28 March issue P.192-P.193 (Published in 1979), published by the Society of Polymer Science, "Experimental Polymer Science Vol. 6 High "Molecular Reactions" (published by Kyoritsu Publishing Co., Ltd. in 1978), pages 148 to 192, written by Fumio Ide, "Graft Polymerization and its Applications" (Kobunshi Publishing Co., Ltd., published in 1977), pages 5 to 148. In other words, using radical attacks on pre-existing polymers such as polymerization initiator radicals and propagating chain radicals,
Or by using a polymerization initiator such as a polymer peroxide, a polymer azobis compound, a combination of a polymer with a hydroxyl group and a cerium salt (iv), or by irradiating the polymer or polymerization system with light or radiation. A method based on a radical mechanism, such as the use of radicals in the generated polymer molecules or radicals generated in the polymer molecules cut by mechanical treatment. A method based on a mechanism that utilizes ion radicals generated in polymer molecules. α- for polymers with functional groups such as amino groups, hydroxyl groups, carboxylic acid groups, and carboxylic acid amides.
A method that utilizes a condensation reaction or ring-opening reaction between a monomer and a functional group in a polymer, such as reacting an epoxide to obtain a graft polymer. A method of copolymerizing a polymer with a polymerizable functional group at the end of the molecule, that is, a macromonomer, and other monomers. A method to obtain a grafted product by reacting polymers with active functional groups, living polymers, etc. between polymers. Examples include, but are not limited to, at least one of the aforementioned polymers and monomers constituting the polymers, and monomers constituting the polymers. The polymer dispersion stabilizer used in the present invention may be manufactured using at least one of the following. The polymer dispersion stabilizer produced in this way is subjected to a neutralization reaction with alkali metal hydroxides, amines, ammonia, etc., or carboxylic acids, etc., as necessary, to make the hydrophilic polymer portion water-soluble. can do. In order to obtain the emulsion (B) of the present invention, a monomer () consisting of a derivative of acrylic acid or methacrylic acid is dispersed in water using the above-mentioned polymer dispersion stabilizer in the presence of the polymer dispersion stabilizer. Perform emulsion polymerization. As a method for this emulsion polymerization, generally known emulsion polymerization methods may be used, and known radical polymerization initiators, chain transfer agents, etc. may be used, and if necessary, a solvent as a film-forming aid, Ordinary emulsion polymerization additives such as plasticizers may be added. The emulsion (B) obtained in this manner may be mixed with a film-forming agent, a plasticizer, a dye/pigment, an antifoaming agent, a rust preventive, a fungicide, etc., as required. The epoxy compound (A) and the emulsion (B) may be mixed at a compounding ratio of 0.05 to 2.5, preferably 0.2 to 1.2, as shown by the following formula. Blending ratio = Equivalent of epoxy group in epoxy compound (A)/Equivalent of functional group reacting with epoxy group of (A) in emulsion composition (B) If this blending ratio is less than 0.05, The crosslinking effect of the epoxy compound is small, and if the crosslinking value exceeds 2.5, the epoxy compound (A) that has not completed the reaction will remain in the coating film for a relatively long time, significantly reducing the water resistance of the coating film, and further reducing the This is because the hardness also decreases. The aqueous coating composition of the present invention thus obtained can be applied to an object by a conventional coating method, and the coating film is cured by heating at room temperature or a relatively low temperature. The aqueous coating composition of the present invention has the following industrial advantages. a) Because it is water-based, it is advantageous in terms of resource saving, environmental issues, fire prevention, and occupational safety and health. b Cures at room temperature, saving energy and resources. c. Since it hardens at room temperature, it does not require energy sources (equipment) such as heat sources and radiation, which is advantageous industrially. d) It is also possible to significantly increase the curing rate and increase work efficiency by heating using a simple heat source. e The aqueous coating composition obtained by the present invention has water resistance, solvent resistance, chemical resistance, weather resistance, adhesion,
It is highly economical and is suitable for various paints, especially metal paints and paints for objects that cannot be heated and dried at high temperatures. Next, the present invention will be explained by examples. In the Examples and Comparative Examples, parts and % indicate parts by weight and % by weight unless otherwise specified. Example 1 [Polymerization of hydrophilic polymer moiety] 29.3 parts of 2-butoxyethanol is charged into a reactor equipped with a stirrer, a reflux condenser, a thermometer, and a dropping device, and heated to 100°C. Add 10.5 parts of acrylic acid and ethyl acrylate to this under a nitrogen atmosphere.
7.5 parts, methyl methacrylate 16.9 parts, 2-ethylhexyl methacrylate 15.0 parts, methacrylic acid 2-
A mixture of 1.0 parts of hydroxyethyl, 1.1 parts of N-methylolacrylamide and 3.7 parts of α,α-azobisisobutyronitrile is added dropwise over 2 hours. One hour after the completion of the dropwise addition, 0.4 parts of α,α-azobisisobutyronitrile and 3.5 parts of 2-butoxyethanol were further added, and polymerization was carried out at 100°C for 6 hours. [Polymerization of a relatively lipophilic polymer portion with good compatibility with a polymer made from a monomer consisting of a derivative of acrylic acid or methacrylic acid] Then, the temperature in the system was lowered to 70°C, and n-butyl methacrylate was added. 10.1 parts, glycidyl methacrylate 0.3
A mixture of 0.5 parts of α,α-azobisisobutyronitrile and 0.2 parts of n-dodecylmercaptan is added dropwise over a period of 2 hours. Thereafter, the temperature was maintained at 70°C and a polymerization reaction was carried out for 8 hours. [As stated in the claims]
(C) Production method of polymer dispersion stabilizer = method of obtaining a graft polymer by reacting polymers having active functional groups between polymers] Next, the temperature of the system was raised to 140°C, and 2
Perform a time reaction. Thus solid content 62.4%, acid value
82 polymer dispersion stabilizer solution is obtained. [Polymerization of an emulsion reacting with the epoxy group of (A) described in the claims] The above polymer dispersion stabilizer solution is placed in a reactor equipped with a separate stirrer, reflux condenser, thermometer, and dropping device.
18.5 parts, 1.5 parts of 28% aqueous ammonia, methacrylic acid n [as a monomer () consisting of a derivative of acrylic acid or methacrylic acid according to claim (B)]
-Add 28.8 parts of butyl and 44.2 parts of water and disperse with sufficient stirring. An aqueous solution of 0.1 part of potassium persulfate dissolved in 6.9 parts of water is added to the obtained aqueous dispersion under a nitrogen atmosphere, and a polymerization reaction is carried out at 80°C for 3 hours. [Reaction between (B) and (A) described in the claims]
The solids content thus obtained is 40.2% and the viscosity is 230CPS.
Add and mix 4.8 parts of the hydrophilic epoxy compound Denacol EX-313 (manufactured by Nagase Sangyo Co., Ltd.) to 100 parts of emulsion at (30℃), and coat it on a mild steel plate using a No. 30 bar coater. Table 1 shows the performance of the coating film obtained after three days of drying. Example 2 [Polymerization of a relatively lipophilic polymer moiety with good compatibility with a polymer made from a monomer () consisting of a derivative of acrylic acid or methacrylic acid=polymer having a polymerizable functional group at the molecular end Polymerization] 71.9 parts of xylene was placed in a reactor equipped with a stirrer, reflux condenser, thermometer, and dropping device, and the temperature was heated to 100°C.
Heat to. This product was mixed with 13.4 parts of methyl methacrylate, 5.8 parts of 2-ethylhexyl acrylate, 1.5 parts of thioglycolic acid and α,α'-
1.4 parts of azobisisobutyronitrile is added dropwise over 2 hours. Three hours after the completion of the dropwise addition, 0.3 parts of α,α'-azobisisobutyronitrile and 3.3 parts of xylene were added, and a polymerization reaction was carried out at 100°C for 6 hours. Next, the temperature inside the system was raised to 140℃, and 1.5% of hydroquinone was added.
% glycidyl methacrylate was added dropwise over 30 minutes, and the mixture was further reacted at 140°C for 4 hours. Thereafter, a portion of the xylene was removed by vacuum distillation to obtain a polymer xylene solution with a solid content of 67.4%. [Polymer dispersant obtained by copolymerizing a polymer having a polymerizable functional group at the molecular end with another monomer:
A polymer composed of other monomer parts corresponds to the hydrophilic polymer part] 17.1 parts of 2-butoxyethanol was charged into another reactor of the same type as above, heated to 100°C, and heated under a nitrogen atmosphere. Then, 23.5 parts of the polymer xylene solution, 11.8 parts of methyl methacrylate, 8.7 parts of 2-ethylhexyl acrylate, 7.1 parts of acrylic acid, and 1.9 parts of α,α'-azobisisobutyronitrile were added dropwise over 2 hours. One hour after the completion of the dropwise addition, 0.3 parts of α,α'-azobisisobutyronitrile and 2.9 parts of 2-butoxyethanol were added, and the reaction was carried out at 100°C for 7 hours. After that, 26.7 parts of water was added and part of the water and part of the organic solvent were removed by distillation, resulting in a solid content of 50.4%.
A polymer dispersion stabilizer-containing liquid with an acid value of 64 was obtained. [Polymerization of an emulsion that reacts with the epoxy group of (A) described in the claims] 48.0 parts of water is added to 21.1 parts of the polymer dispersion stabilizer-containing solution.
part, 0.4 part of 28% ammonia water, Claims (B)
Methyl methacrylate as a monomer () consisting of a derivative of acrylic acid or methacrylic acid as described in
20.2 parts of acrylate, 8.7 parts of 2-ethylhexyl acrylate, and 0.1 part of divinylbenzene were added and dispersed with thorough stirring. An aqueous solution of 0.1 part of potassium persulfate dissolved in 1.4 parts of water is added to the obtained aqueous dispersion, and a polymerization reaction is carried out at 80° C. for 3 hours in a nitrogen atmosphere.
[Reaction between (B) and (A) described in the claims] To 100 parts of the thus obtained emulsion having a solid content of 39.9% and a viscosity of 160 cps (30°C), a hydrophilic epoxy compound Denacol EX-313 (Nagase Sangyo Co., Ltd. ) was added and mixed, and then coated on a mild steel plate using a No. 30 bar coater. Table 1 shows the performance of the coating film obtained by drying at 60°C for 100 minutes. Example 3 [Polymerization of hydrophilic polymer moiety] 39.9 parts of 2-butoxyethanol is charged into a reactor equipped with a stirrer, a reflux condenser, a thermometer, and a dropping device, and heated to 100°C. This was added to 8.1 parts of ethyl acrylate, 18.2 parts of methyl methacrylate, and 2-ethylhexyl methacrylate under a nitrogen atmosphere.
16.2 parts, 2-hydroxyethyl methacrylate 1.1
1.2 parts of N-methylolacrylamide, 11.3 parts of acrylic acid and 4.0 parts of α,α'-azobisisobutyronitrile were added dropwise over 2 hours. After the dropwise addition was completed, the temperature was raised to 120°C and the reaction was carried out for 6 hours. A carboxylic acid group-containing polymer solution with a solid content of 59.4% and an acid value of 88 was thus obtained. [Polymerization of a relatively lipophilic polymer portion with good compatibility with a polymer made from a monomer () consisting of a derivative of acrylic acid or methacrylic acid] 40.1 parts of xylene was charged in another reactor of the same type. Heat to 80℃. A mixture of 54.9 parts of n-butyl methacrylate, 1.7 parts of glycidyl methacrylate, 0.8 parts of n-dodecylmercaptan and 2.5 parts of α,α-azobisisobutyronitrile was added dropwise to this mixture over 2 hours under a nitrogen atmosphere. 80℃ after completion of dripping
The reaction was carried out for 8 hours. Thus, an epoxy group content polymer solution with a solids content of 58.3% was obtained. [Production of polymer dispersant according to claim (C)] 83.0 parts of the above carboxylic acid group-containing polymer solution and 17.0 parts of the epoxy-containing polymer solution were subjected to an intermolecular reaction at 130°C for 3 hours, and then Part of the xylene and 2-butoxyethanol is removed by distillation,
A polymer dispersion stabilizer solution with a solid content of 70.3% and an acid value of 73 was obtained. [Polymerization of an emulsion that reacts with the epoxy group of (A) described in the claims] 16.2 parts of the polymer dispersion stabilizer solution, 8.5 parts of 30% water-moist nitrocellulose (SS1/4), [Claims] (B) radically polymerizable unsaturated monomer described in]
() as n-butyl methacrylate 23.6 parts, water
Add 46.7 parts and 1.4 parts of 28% aqueous ammonia and disperse with thorough stirring. An aqueous solution of 0.1 part of potassium persulfate dissolved in 3.5 parts of water is added to the resulting aqueous dispersion under a nitrogen atmosphere, and a polymerization reaction is carried out at 80°C for 3 hours. [Reaction between (B) and (A) described in the claims] Solid content 40.1% and viscosity 170 cps thus obtained
Hydrophilic epoxy compound Denacol EX-313 (manufactured by Nagase Sangyo Co., Ltd.) was added to 100 parts of the emulsion composition at 30°C.
4.5 parts were added and mixed and coated on a mild steel plate using a No. 30 bar coater. Table 2 shows the performance of the coating film obtained after drying at room temperature for 3 days. Example 4 [Polymerization of a relatively lipophilic polymer moiety with good compatibility with a polymer made from a monomer () consisting of a derivative of acrylic acid or methacrylic acid] In the reactor used in Example-1 , xylene
Prepare 67.1 part and heat to 100℃. To this mixture were added 28.2 parts of n-butyl methacrylate, 1.3 parts of thioglycolic acid and 0.3 parts of α,α'-azobisisobutyronitrile under a nitrogen atmosphere, and the polymerization reaction was further carried out at 100°C for 6 hours. [Terminal end of lipophilic polymer moiety - SH group]

[Synthesis of a lipophilic polymer having a terminal C=C bond by reacting [Formula]] Next, 1.8 parts of glycidyl methacrylate and 0.02 parts of hydroquinone
1 part was added and the reaction was carried out at 140°C for 4 hours. [Polymer with a polymerizable functional group at the molecular end, i.e., a polymer dispersion stabilizer obtained by copolymerizing a macromer with other monomers - a polymer consisting of other monomers] Polymerization of (backbone polymer) corresponding to a hydrophilic polymer] Solid content thus obtained
Add 17.1 parts of 2-butoxyethanol to 23.5 parts of the lipophilic polymer solution, maintain the system temperature at 100°C, and add 14.8 parts of methyl methacrylate under a nitrogen atmosphere.
7.1 parts of acrylic acid, 8.0 parts of 2-ethylhexyl methacrylate, 0.7 parts of dicyclopentynyl methacrylate, and 1.9 parts of α,α'-azobisisobutyronitrile were added dropwise over 2 hours. 3 hours after completion of dropping, α,α′-azobisisobutyronitrile 0.3
A mixture of 1 part and 4.9 parts of 2-butoxyethanol was added, and the polymerization reaction was further carried out for 6 hours. then water
23.7 parts were added, and part of the water and organic solvent was removed by distillation to obtain a polymeric dispersion stabilizer with a solid content of 55.8% and an acid value of 55. [Reaction of grafting an acrylic polymer onto CAB in order to improve the compatibility of CAB = Not directly related to the scope of claims] On the other hand, in another reactor of the same type, the epoxy group obtained in Example-3 was added. Containing polymer solution 5.5 parts, xylene
48.7 parts, cellulose acetate butyrate (CAB381-0.1, manufactured by Eastman Chemical Company) 7.8
1 part and 0.1 part of N,N-dimethylbenzylamine were charged, and the reaction was carried out at 130°C for 5 hours. Next, 37.9 parts of the above-mentioned polymeric dispersion stabilizer is added, and then a portion of the xylene and 2-butoxyethanol is removed by distillation to obtain a graft-modified cellulose derivative-containing liquid with a solid content of 64.2%. [Polymerization of an emulsion that reacts with the epoxy group of (A) described in the claims] A monomer consisting of the acrylic acid or methacrylic acid derivative described in the claims (B) is added to 29.3 parts of this containing liquid. 22.4 parts of n-butyl methacrylate, 1.5 parts of 28% aqueous ammonia, and 42.8 parts of water were added as the body (2), and dispersed with stirring.
Add 0.1 part of potassium persulfate to the resulting aqueous dispersion and add 3.9 parts of water.
Add an aqueous solution dissolved in one part and carry out a polymerization reaction at 80°C for 3 hours. [Reaction between (B) and (A) described in the claims] Solid content of 40.8% and viscosity obtained in this way
3.9 parts of the hydrophilic epoxy compound Denacol EX-313 (manufactured by Nagase Sangyo Co., Ltd.) was added to 100 parts of 560 cps emulsion, mixed, and coated on a mild steel plate using a No. 30 bar coater at 60°C for 100 minutes. Table 2 shows the performance of the coating film obtained by drying. Comparative Example 1 The emulsion obtained in Example 1 was coated on a mild steel plate using a No. 30 bar coater and dried at room temperature for 3 days. Table 1 shows the performance of the coating film. Comparative Example 2 Water was placed in the same type of reactor used in Example-1.
Charge 52.4 parts and 1.2 parts of sodium dodecylbenzenesulfonate and heat to 80°C. Add to this 1.4 parts of ethyl acrylate and methyl methacrylate.
3.2 parts, 2-ethylhexyl methacrylate 2.8 parts,
2-hydroxyethyl methacrylate 0.2 parts, acrylic acid 2.0 parts, n-butyl methacrylate 31.3 parts,
8.0 parts of a radically polymerizable monomer mixture consisting of 0.1 part of glycidyl methacrylate and 0.2 parts of N-methylol acrylamide, and 0.1 part of potassium persulfate were mixed with water.
1.0 part of an aqueous solution dissolved in 5.0 parts of each was separately charged and reacted for 1 hour under a nitrogen atmosphere. Next, the remaining 33.2 parts of the above radically polymerizable monomer mixture and 4.1 parts of the above potassium persulfate aqueous solution were each added dropwise over 2 hours, and further heated at 80°C for 3 hours.
Stir for an hour. The solid content thus obtained was 41.0%.
Add and mix 4.8 parts of a hydrophilic epoxy compound (Denacol EX-313) to an emulsion with a viscosity of 347 cps (30°C), coat it on a mild steel plate using a No. 30 bar coater, and dry for 3 days at room temperature. Table 1 shows the performance of the resulting coating film. Comparative Example 3 The emulsion obtained in Example 3 was coated on a mild steel plate using a No. 30 bar coater and dried at room temperature for 3 days. The performance of the coating film is shown in Table 2. Comparative Example 4 In a reactor similar to Example-1, 8.9 parts of 30% wet nitrocellulose (SS1/4), 3.6 parts of methyl methacrylate, 23.7 parts of n-butyl methacrylate, 2.3 parts of acrylic acid, and 2 parts of methacrylic acid were added. -Ethylhexyl
Add 4.1 parts of ethyl acrylate, 1.6 parts of ethyl acrylate, 1.3 parts of sodium dodecylbenzenesulfonate, and 1.3 parts of an anionic complex phosphate emulsifier (Gatac RE-610 manufactured by Toho Chemical Industry Co., Ltd.) and disperse while thoroughly stirring. . An aqueous solution of 0.1 part of potassium persulfate dissolved in 1.6 parts of water was added to the obtained aqueous dispersion, and polymerization was carried out at 80°C for 3 hours in a nitrogen atmosphere to reduce the solid content.
An emulsion of 43.6% and a viscosity of 120 cps (30°C) was obtained. 4.5 parts of the hydrophilic epoxy compound Denacol EX-313 (manufactured by Nagase Sangyo Co., Ltd.) was added to 100 parts of the emulsion, mixed, coated on a mild steel plate using a No. 30 bar coater, and dried at room temperature for 3 days. Table 2 shows the performance of the coating film obtained.

【table】

【table】

[Table] The evaluation results are expressed in five grades: ◎, ○, ○△, △, and ×. ◎ to ○△ are acceptable for use, and △ to × are not suitable for practical use.

Claims (1)

[Claims] 1 (A): A hydrophilic epoxy compound having two or more epoxy groups per molecule. (B): An emulsion obtained by polymerizing a monomer () consisting of at least one derivative of acrylic acid or methacrylic acid in water in the presence of a polymeric dispersion stabilizer consisting of the following (C). In some cases, the emulsion has a functional group that reacts with the epoxy group of (A). (C): A polymer dispersion stabilizer containing a lipophilic polymer part and a hydrophilic polymer part in the same molecule, where the hydrophilic polymer part is made of acrylic acid or methacrylic acid of (B). Polymer dispersion stabilizer with good compatibility with polymers made from monomers () consisting of derivatives. The above (A) and (B) were blended in a ratio of equivalent of epoxy group in epoxy compound (A)/equivalent of functional group reacting with epoxy group in emulsion composition (B) = 0.05 to 2.5. An aqueous coating composition characterized by: