JPH0583108B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Purpose of the invention <Field of industrial application> The present invention relates to a coating composition applied to the surfaces of various articles such as metals, and the coating composition of the present invention has corrosion resistance, water resistance, It provides a coating film with excellent properties such as durability and solvent resistance, and is widely used in industries that handle metal products such as the automobile industry and electrical equipment manufacturing, and industries that handle wood products such as furniture woodworking. It is. <Prior Art> Conventionally, various water-soluble resins and emulsion-type resins have been coated on the surfaces of various articles to impart corrosion resistance, water resistance, and the like. However, all of these resins have major problems. In other words, water-soluble resins have many hydrophilic groups and relatively low molecular weight, so unless they are cross-linked by adding melamine or the like, they have poor corrosion resistance and solvent resistance, and emulsion-type resins have poor corrosion resistance for metals due to the emulsifier they contain. properties and adhesion of the coating,
Water resistance cannot be expected. On the other hand, in order to improve corrosion resistance, water resistance, and solvent resistance, for example, compounds having two or more ethylenically unsaturated groups are copolymerized to have a high molecular weight.
A method has been adopted in which ethylenically unsaturated monomers having epoxy groups, amide groups, methylolamide groups, etc. are copolymerized and crosslinked during polymerization, film formation, or after film formation. However, even with these methods, if a large amount of the monomer is used in emulsion polymerization, it becomes difficult to proceed smoothly with the polymerization, and as the crosslinking density increases, the film becomes harder than necessary, and other There is a limit to the improvement in physical properties that can be obtained, such as hindering the physical properties of . Furthermore, many crosslinking agents exist as additives, but their high reactivity causes poor liquid stability and limits their practical use in order to exhibit excellent properties. <Problems to be Solved by the Invention> The present inventors have solved the above-mentioned problems of conventional coating compositions, and have developed a coating composition that provides excellent corrosion resistance and excellent solvent resistance, water resistance, etc. Various studies were conducted in order to find a coating composition that would provide a coating film with a high quality coating. (b) Structure of the invention <Means for solving the problem> The present inventors have developed a specific acrylate having a urethane bond (hereinafter referred to as urethane acrylate).
The present invention was completed based on the discovery that a coating composition comprising an emulsion polymer having as a constituent component satisfies the above requirements. That is, the present invention uses the following monomer (A) in an amount of 1 to 80% by weight.
The present invention relates to a coating composition comprising an emulsion polymer containing 20 to 99% by weight of the following monomer (B) as a constituent component. Monomer (A)

[Chemical formula] (However, R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkyl group having 1 to 8 carbon atoms, and R ₃ is an alkylene group having 2 to 4 carbon atoms.) Monomer (B) Ethylenically unsaturated monomer Γ urethane acrylate copolymerizable with monomer (A) Urethane acrylate used in the present invention is
It is represented by the structural formula below.

[Chemical formula] (However, R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkyl group having 1 to 8 carbon atoms, and R ₃ is an alkylene group having 2 to 4 carbon atoms.) These urethane acrylates Among these, those in which R ₂ has 1 carbon atom are preferred for the present invention.
-4 lower alkyl group, especially butyl group, R ₃
is an ethylene group. These urethane acrylates are
It can be easily produced by the method described in JP-A No. 60-155276 and JP-A-58-79063, and commercially available butylcarbamoyloxy ethyl acrylate, butylcarbamoyloxy ethyl methacrylate, etc. are also used in the present invention. It can be used for. The amount of urethane acrylate in the emulsion polymer is 1
~80% by weight, and if it is less than 1% by weight, it is insufficient to impart corrosion resistance, solvent resistance, water resistance, etc., and if it is more than 80% by weight, it will gel during emulsion polymerization and cause the polymer to deteriorate. difficult to obtain. A particularly preferred range is 2 to 50% by weight. Γ Ethylenically unsaturated monomer Examples of the ethylenically unsaturated monomer used in the present invention include the following. These are selected depending on the purpose, copolymerizability, etc., and one or more types are used. 1 α/β-unsaturated carboxylic acid esters, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-methacrylate Alkyl esters of acrylic acid or methacrylic acid such as butyl, isobutyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, hydroxyalkyl acrylates and methacrylates such as hydroxypropyl acrylate, amino group-containing esters of dimethylaminoethyl methacrylate, Glycidyl group-containing esters such as glycidyl methacrylate, and esters of maleic acid, fumaric acid, and itaconic acid. 2 Amides of α/β-unsaturated acids, such as acrylamide, methacrylamide, maleic acid amide and maleic imide. 3 Substituted amides of unsaturated carboxylic acids, e.g. N-
Methylol acrylamide and methacrylamide, diacetone acrylamide, N-butoxymethyl acrylamide, etc. 4 Vinyl esters such as vinyl acetate, vinyl propionate and vinyl chloride. 5 Nitriles of α/β-unsaturated carboxylic acids, such as acrylonitrile, methacrylonitrile, etc. 6 Vinyl ethers, such as vinyl ethyl ether. 7 Vinyl ketones, such as vinyl methyl ketone. 8 vinylamide, e.g. vinylformamide,
Vinylacetamide etc. 9 Aromatic vinyl compounds, such as styrene, vinyltoluene, etc. 10 Heterocyclic vinyl compounds, such as vinylpyridine, vinylpyrrolidone, etc. 11 Vinylidene halides compounds, such as vinylidene chloride, vinylidene fluoride, etc. 12 Divinyl compounds, such as divinylbenzene,
butanediol dimethacrylate etc. 13 α-Olefins, such as ethylene, propylene, etc. 14 Diolefins, such as butadiene, isoprene, etc. 15 Allyl compounds such as allyl acetate, allyl alcohol and diallyl phthalate. 16 Unsaturated monobasic acids such as acrylic acid and methacrylic acid and their salts, unsaturated dihydrochloric acids such as itaconic acid, fumaric acid and maleic acid, their half esters and their salts, etc. By combining various types of these monomers, for example, acrylic esters that give soft polymers, and methacrylic esters and styrene that give hard polymers, it is possible to change resins from hard to soft, from room temperature drying to drying. Various types of resins can be obtained, including heat-dried types. Preferred ethylenically unsaturated monomers for the present invention include common acrylic acids such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Alternatively, a monomer or a monomer mixture whose main component is one or more monomers selected from alkyl esters of methacrylic acid and aromatic vinyl compounds such as styrene is preferable. More preferred ethylenically unsaturated monomers for the present invention include monomers in which the monomer or monomer mixture has a carboxyl group shown in 16) above, such as acrylic acid and methacrylic acid.
0.5 to 15% by weight, particularly preferably 1% by weight in the total monomers
The content is 8% by weight. By neutralizing the polymer obtained using these monomers with a base, a very stable emulsion polymer can be obtained, which is preferred for the present invention. Furthermore,
Copolymerization of monomers having carboxyl groups or hydroxyl groups can further improve corrosion resistance, water resistance, and solvent resistance by incorporating melamine resins, epoxy resins, etc. On the other hand, the amount of the monomer having such a hydrophilic functional group is desirably 20% by weight or less based on the total monomers. Also,
If a reactive monomer is used, it can be made into a bake-curable resin, and various properties can be achieved. Γ Emulsion Polymerization Method The coating composition of the present invention may be produced by a method similar to a known method. For example, a reactor is charged with deionized water and an emulsifier. Next, the mixture is degassed with nitrogen gas, and a mixture of monomers is sequentially charged while heating and stirring, and a polymerization reaction is carried out according to a conventional method. Further, the monomer mixture may be emulsified in advance with deionized water and an emulsifier, if necessary. At this time, the monomers may be added all at once, divided, or continuously. As the emulsifier here, ordinary emulsifiers such as anionic, nonionic, cationic, and amphoteric emulsifiers can be used, but the amount should be kept as low as possible since using too much will reduce corrosion resistance and water resistance.
Preferably, it is used in an amount equivalent to 2% by weight or less of the total monomers. In addition, a method of polymerization without using an ordinary emulsifier is a preferable method, for example,
A method in which the monomer is polymerized using only a polymerization initiator such as ammonium persulfate, a method in which the monomer is polymerized in a water-soluble or water-dispersible polymer resin, etc. can be employed. When polymerizing in water-soluble or water-dispersible polymer resins, various modified epoxy resins,
Modified polyolefin resins, copolymers of styrene and maleic acid, copolymers of isobutylene and maleic acid, polyacrylic acid, etc. are used. In the preferred method of polymerization in a water-soluble or water-dispersible polymer resin, a preferred method for particularly improving water resistance and corrosion resistance is disclosed in JP-A-57-145102.
A method using an alkaline aqueous solution of carboxyl group-containing polyolefin as a polymer resin disclosed in 2003, and a method of esterifying the terminal epoxy group of an epoxy resin with a phosphorus-containing acid as a polymer resin proposed in Japanese Patent Application No. 60-253578. A method of polymerizing in a water-soluble or water-dispersible modified epoxy resin which is then neutralized with a base can be mentioned. According to this emulsion polymerization method, the adverse effects caused by ordinary emulsifiers can be significantly reduced. Radical generating catalysts used in polymerization include:
Examples include hydrogen peroxide, t-butyl hydroperoxide, ammonium persulfate, potassium persulfate, etc., which are diluted with deionized water and added dropwise or all at once. The reaction temperature is preferably 100°C or less, more preferably 30 to 90°C,
Polymerize at that temperature for 2 hours or more. In this case, if a reducing agent such as soda sulfite, ferrous sulfate, or Rongarit is used in combination, the polymerization reaction can proceed smoothly even at low temperatures. After the polymerization is completed, if desired, neutralization is performed with a base to adjust the pH to 5 to 10 to obtain a stable milky white emulsion polymer. In this case, when aqueous ammonia or amine is used, the pH is preferably adjusted to 6 to 8 from the viewpoint of odor. The coating composition thus obtained can usually have a solids content of 60% or less. Γ Use The coating composition of the present invention is used for corrosion prevention of metals, paper and
For moisture and water resistance of fibers, wood, slate boards, etc.
It is useful for surface coating of glass and plastics, and as a binder for various slurries and pigments. The coating composition of the present invention may contain crosslinking agents such as urea resins and melamine resins, other water-soluble organic resins such as phenolic resins and epoxy resins, and water-dispersible or water-soluble inorganic substances such as colloidal silica. On the other hand, pigments such as titanium oxide and calcium carbonate, general rust preventive pigments, temporary rust preventive agents, inhibitors such as water-soluble chromium compounds, etc. may be added to improve the rust prevention properties. Further, thickeners, dispersants, film-forming aids, antifoaming agents, preservatives, freeze stabilizers, organic solvents, etc. may be added. As a method for coating various articles with the composition of the present invention thus prepared, conventional methods such as brush coating, spray coating, roll coating, and dip coating can be used. Drying after application is adjusted based on the composition or film thickness, and is usually kept at room temperature to 200°C.
Dry at a temperature of 5 seconds to 15 minutes. For example, when a crosslinking agent such as the above-mentioned urea resin or melamine resin is added, drying and baking hardening are performed at a temperature of about 100 to 200°C. The film thickness is not particularly limited depending on the purpose and use, but when used as a paint, the dry film thickness is usually adjusted to about 0.1 to 20 μm. <Function> How does the coating composition comprising the emulsion polymer containing urethane acrylate of the present invention provide the excellent corrosion resistance described herein, and improve solvent resistance, water resistance, etc.? It is unclear whether it can be used as a coating composition that provides an excellent coating film, and as previously described in JP-A-60-155276 and JP-A-58-79063, ultraviolet rays and other high-energy rays It is also unclear why urethane acrylate acid, which has been primarily used as a reactive diluent in resin compositions that are cured by polyurethane, can have such an effect. <Examples> The present invention will be described in more detail below with reference to Examples and Comparative Examples. Further, parts and percentages used below indicate parts by weight and percentages by weight unless otherwise specified. Example 1 35 parts of bisphenol A diglycidyl ether (epoxy equivalent: 250) was dissolved in 15 parts of methyl ethyl ketone, 3 parts of orthophosphoric acid was further mixed with the solution, and the reaction was carried out at 50°C for 3 hours, followed by 70°C. The temperature was raised to 100%, and the reaction was further carried out for 7 hours to obtain a phosphoric acid esterified epoxy resin. The epoxy resin had a solid content of 70%, a varnish acid value of 140, and a viscosity of 120 ps. After adding 7 parts of 25% ammonia water and stirring well, add 1183 parts of deionized water and continue stirring.
The pH of the system was adjusted to 5.0 with 25% ammonia water, and the phosphoric acid esterified epoxy resin was dispersed in water. The above dispersion was transferred to a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65° C. while stirring. Then, while maintaining the temperature at 65°C, a mixed ethylenically unsaturated monomer consisting of 300 parts of ethyl acrylate, 330 parts of ethyl methacrylate, 35 parts of methacrylic acid, and 35 parts of butylcarbamoyloxyethyl acrylate, t-butyl hydroperoxide was added. An aqueous solution of 3.5 parts of Rongalit in 53 parts of deionized water and an aqueous solution of 3.5 parts of Rongalit in 53 parts of deionized water are each added dropwise through separate addition funnels over a period of 6 hours. After the dropwise addition was completed, stirring and heating were continued for 2 hours to complete the reaction, and an emulsion polymer having a pH of 5.0 and a solid content of 35% was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia to obtain a coating composition. Example 2 Same method as Example 1, but mixed ethylenically unsaturated monomers were mixed with 50 parts of ethyl acrylate, 50 parts of n-butyl acrylate, 110 parts of styrene, 315 parts of ethyl methacrylate, and 35 parts of methacrylic acid. , and 140 parts of butylcarbamoyloxyethyl acrylate to obtain an emulsion polymer with a pH of 5.0 and a solid content of 35%. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia to obtain a coating composition. Example 3 The same method as in Production Example 1 was used, but the mixed ethylenically unsaturated monomers were mixed with 50 parts of ethyl acrylate, 150 parts of n-butyl acrylate, and 115 parts of methyl methacrylate.
parts, 35 parts of acrylic acid, and 350 parts of butylcarbamoyloxyethyl acrylate,
An emulsion polymer with a pH of 5.0 and a solids content of 35% was obtained. after that
The pH of the system was adjusted to 7.5 with 25% aqueous ammonia to obtain a coating composition. Example 4 Zaixen A (ammonium salt of ethylene/acrylic acid copolymer, manufactured by Steel Chemical Industry Co., Ltd.) was placed in a flask equipped with a stirrer, a cooling tube, and a temperature control device.
1867 parts and 533 parts of deionized water were added, and the temperature was raised to 65°C while stirring. Then, while maintaining the temperature at 65°C, a mixed ethylenically unsaturated monomer consisting of 250 parts of ethyl acrylate, 275 parts of ethyl methacrylate, 35 parts of methacrylic acid, and 140 parts of butylcarbamoyloxyethyl acrylate, t-butyl hydroperoxide was added. An aqueous solution of 3.5 parts of Rongarit in 117 parts of deionized water and 3.5 parts of Rongarit in 117 parts of deionized water.
Each portion of the aqueous solution was added dropwise using a separate dropping funnel over a period of 6 hours. After the dropwise addition was completed, stirring and heating were continued for 2 hours to complete the reaction, and a coating composition containing an emulsion polymer having a pH of 8.5 and a solid content of 35% was obtained. Example 5 The same method as in Production Example 4 was used, but the mixed ethylenically unsaturated monomers were mixed with 50 parts of ethyl acrylate, 50 parts of n-butyl acrylate, 110 parts of styrene, 105 parts of ethyl methacrylate, and 35 parts of methacrylic acid. A coating composition containing an emulsion polymer having a pH of 8.3 and a solid content of 35% was obtained by replacing the mixture with 350 parts of butylcarbamoyloxyethyl acrylate. Example 6 700 parts of deionized water was placed in a flask equipped with a stirrer, a condenser, and a temperature control device, and the temperature was raised to 65° C. while stirring. Then, while maintaining the temperature at 65°C, a mixed monomer consisting of 200 parts of ethyl acrylate, 115 parts of ethyl methacrylate, 35 parts of methacrylic acid, and 350 parts of butylcarbamoyloxyethyl acrylate was added to polyoxyethylene, an anionic surfactant. Sodium alkyl ether sulfate 2
A monomer emulsion pre-emulsified in a homomixer, an aqueous solution of 3.5 parts of t-butyl hydroperoxide dissolved in 154 parts of deionized water, and 3.5 parts of Rongarit were deionized. Each aqueous solution in 154 parts of water is added dropwise over a period of 4 hours using separate addition funnels. After the dropwise addition was completed, stirring and heating were continued for 2 hours to complete the reaction, and an emulsion polymer with a pH of 5.0 and a solid content of 35% was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia to obtain a coating composition. Comparative Example 1 Same method as Example 1, but mixed ethylenically unsaturated monomers were mixed with 350 parts of n-butyl acrylate,
A mixed solution consisting of 315 parts of ethyl methacrylate and 35 parts of methacrylic acid was used to obtain an emulsion polymer having a pH of 3.5 and a solid content of 35%. Thereafter, the pH of the system was adjusted to 6.5 with 25% aqueous ammonia to obtain a coating composition. This comparative example is a case in which the same polymerization method as in Example 1 is used, and the amount of urethane acrylate in the mixed monomer is below the range of the present invention (0%). Comparative Example 2 The same method as in Example 1 was used, but the mixed ethylenically unsaturated monomer was replaced with a mixed solution consisting of 35 parts of n-butyl acrylate, 35 parts of methacrylic acid, and 630 parts of butylcarbamoyloxyethyl acrylate.
When polymerization was carried out, it turned into a gel after 3 hours. This comparative example is a case where the amount of urethane acrylate in the mixed monomer is above the range of the present invention (90%). Comparative Example 3 700 parts of deionized water was placed in a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65° C. while stirring. Then, while maintaining the temperature at 65°C, a mixed monomer consisting of 350 parts of ethyl acrylate, 315 parts of ethyl methacrylate, and 35 parts of methacrylic acid was mixed with 2 parts of sodium polyoxyethylene alkyl ether sulfate, an anionic surfactant, and Add 273 parts of ionized water and pre-emulsify the monomer emulsion using a homomixer, add 3.5 parts of t-butyl hydroperoxide to 154 parts of deionized water, and add 3.5 parts of Rongarit to 154 parts of deionized water.
Each portion of the aqueous solution was added dropwise using a separate dropping funnel over a period of 4 hours. After the dropwise addition was completed, stirring and heating were continued for 2 hours to complete the reaction, and an emulsion polymer with a pH of 5.0 and a solid content of 35% was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% aqueous ammonia to obtain a coating composition. In this comparative example, the same polymerization method as in Example 6 was used, but the amount of urethane acrylate in the mixed monomer was below the range of the present invention (0%). Physical Property Test The coating compositions obtained in each of the Examples and Comparative Examples were applied to various substrates to form films, and the following physical property tests were conducted, and the results are shown in Table 1. 1 Corrosion resistance (salt spray test) JIS-Z-
A salt spray test using 2371 was conducted. The area where red rust occurred was evaluated using a 10-point scale. That is, a score of 10 indicates no occurrence of red rust, and a score of 9 indicates up to 10% of the area where red rust has occurred (the same criteria apply hereinafter). a. An SPCC board measuring 150 mm long x 70 mm wide x 0.8 mm thick was degreased and dried in a conventional manner, the coating composition was applied to the steel material, and the coating composition was dried at 70°C for 10 minutes to obtain a test board. The coating film thickness was approximately 10μ. b Bonde plate (#144) of length 150 x width 70 x plate thickness 0.8 mm
The steel material was degreased and dried in a conventional manner, and a coating composition was applied to the steel material, followed by drying at 70°C for 10 minutes to prepare a test plate. The coating film thickness was approximately 10μ. 2 Solvent Resistance It was coated on Bonde board #144 and dried at 70°C for 10 minutes to prepare a test board. The coating film thickness was approximately 10μ. The test plate was immersed in ethanol and the state of the membrane was observed. 〇...No change △...Swelling or slight elution ×...Elution 3 Water resistance It was painted on an aluminum plate and dried at 70°C for 10 minutes to make a test plate. The coating film thickness was approximately 10μ.
The test plate was immersed in water at room temperature for 24 hours and the state of the film was observed. 〇……No change △……Slight whitening ×……Whitening or blister

[Table] As is clear from Table 1, the corrosion resistance of the substrate coated with the composition of the present invention and the solvent resistance and water resistance of the coating film are both good. (C) Effects of the Invention According to the present invention, it is possible to impart excellent corrosion resistance to various products, and to obtain a coating film having excellent solvent resistance, water resistance, etc. It can be arbitrarily selected from flexible materials to hard materials, and can be widely used in a wide range of fields, and the effects brought about by the present invention are immeasurable.

Claims (1)

[Claims] 1 1 to 80% by weight of the following monomer (A) and 20% of the following monomer (B)
A coating composition comprising an emulsion polymer containing ~99% by weight as a constituent component. Monomer (A) [Chemical formula] (However, R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkyl group having 1 to 8 carbon atoms, and R ₃ is an alkylene group having 2 to 4 carbon atoms.) Monomer (B) An ethylenically unsaturated monomer that can be copolymerized with monomer (A).