JPH021868B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a composition for a matte finish electrodeposition coating. (Prior Art) Conventionally, methods for creating a so-called satin finish that creates a decorative effect by forming relatively uniform and fine irregularities on a metal surface to diffusely reflect light and create a decorative effect include (1) liquid honing method, sandblasting method, Methods such as mechanically processing the surface using wet blasting, etc., and (2) chemically processing the surface using etching with alkali or acid are being implemented. However, with either method, after finishing with a satin finish, it is necessary to thoroughly wash the product and then apply anodizing, chromate coating, or clear paint to prevent corrosion and strengthen the surface, making the process complicated. Met. For this reason, there has been a demand for the development of a paint that forms a paint film with a satin appearance just by applying it. (Problems to be Solved by the Invention) An object of the present invention is to provide an electrodeposition coating composition that forms a coating film having a matte appearance by coating, which has not been practiced in the past. (Means for Solving the Problems) To summarize the present invention, (a) the secondary transition point is −10 to 20;
°C α,β-ethylenically unsaturated polycarboxylic acid resin and (b) amino resin as coating film-forming components, and (c) pigment in an amount of 2.0 to 30% by weight based on the coating film-forming components.
The present invention relates to a composition for a satin-like electrodeposition paint, which is obtained by adding and blending. To explain in detail the unique points of the present invention, the α,β-ethylenically unsaturated polycarboxylic acid resin used in the present invention is composed of α,β-ethylenically unsaturated polycarboxylic acid and copolymerizable with this. It is obtained by reacting with a monomer, and its secondary transition point is -10 to 20°C, and the pigment content is 2.0 to 30% by weight of the coating film forming components. is the requirement. In the present invention, the reason why the secondary transition point of α,β-ethylenically unsaturated polycarboxylic acid resin is defined as -10 to 20°C is that when electrodeposition coating is performed, large irregularities on the surface of the deposited resin coating occur. This is to cause the formation. Conventionally, when the secondary transition point of α,β-ethylenically unsaturated polycarboxylic acid resin is 50°C or higher, when the deposited electrodeposited resin coating is heated and baked, the resin melts and the coating surface becomes flat. When the secondary transition point is less than 50°C,
It is known that there is a tendency for the gloss of electrodeposited coatings to improve. (Refer to Japanese Patent Application Laid-Open No. 59-4720) In the present invention, α, β
- Focusing on the use of ethylenically unsaturated polycarboxylic acid resin, we examined it from various angles and found that carbon black is a film-forming component of electrodeposition paint.
The above object was achieved by setting the content to 2.0 to 30% by weight, preferably 5 to 20% by weight. In the present invention, the reason for specifying the amount of carbon black added as described above is that if it is less than 2.0% by weight, a satin-like appearance cannot be obtained, whereas if it exceeds 30% by weight, pinholes will occur in the coating film due to gas. This is not preferable because it may cause problems such as adhesion and other properties of the coating film. Suitable α,β-ethylenically unsaturated polycarboxylic acid resins have an acid value of about 10 to 200.
Those with an acid value of less than 10 cannot be sufficiently dispersed in water,
In addition, it is unstable when used as a coating material, and on the other hand, if the acid value exceeds 200, the electrodeposited coating film will re-dissolve, and the coverage of the coating film will be poor, which is undesirable. Examples of suitable α,β-ethylenically unsaturated carboxylic acids include alluric acid, α-chloroacrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, fumaric acid, crotonic acid, citraconic acid and mesaconic acid. or their functional derivatives having at least one carboxyl group, such as unsaturated polymerizable di-
or partial esters or amides of poly-carboxylic acids. Examples of monomers copolymerizable with α,β-ethylenically unsaturated carboxylic acids include esters of α,β-ethylenically unsaturated carboxylic acids, such as alkyl and oxyalkyl esters, and derivatives such as amides; There are derivatives of unsaturated di- or poly-carboxylic acids that do not contain free carboxyl groups, such as diethyl maleate and dibutyl maleade. Other polymerizable vinyl or vinylidene compounds such as styrene, alkylstyrenes and acrylonitrile may also be used. Examples of alkyl esters of α,β-ethylenically unsaturated carboxylic acids include methyl acrylate,
Methyl metal acrylate ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, acrylamide, diethylene glycol monoacrylate, diethylene glycol methacrylate, methacrylamide, methylol acrylamide, methylol methacrylamide , diacetone acrylamide, diacetone methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, hexyl acrylate, 2-ethylhexyl methacrylate, heptyl acrylate, and heptyl methacrylate. Further, as derivatives of hydroxyalkyl or alkoxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids and α,β-ethylenically unsaturated carboxylic acid amides or amides of α,β-ethylenically unsaturated carboxylic acids, for example, 2 -Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate and 3
-Hydroxypropyl methacrylamide, etc. A copolymer having a secondary transition point of -10 to 20°C can be produced by adjusting the combination and ratio of the monomer with an unsaturated substance having a carboxyl group and other monomers. On the other hand, as the amino resin, melamine resin, benzoguanamine resin, acetoguanamine resin, etc. can be used.
In the present invention, among melamine resins, methylol melamine, which is poorly water-soluble and has been at least partially etherified with one or more monohydric alcohols such as methanol, ethanol, propanol, and butanol, is particularly suitable. The above α and β in the electrodeposition coating composition of the present invention
- The composition ratio of ethylenically unsaturated polycarboxylic acid resin and amino resin can be used in the range of 5 to 95 parts by weight of α,β-ethylenically unsaturated polycarboxylic acid resin and 95 to 5 parts by weight of amino resin. . The electrodeposition coating composition of the present invention can be produced, for example, by the following method. In a container equipped with a stirrer and a thermometer, (a) an α,β-ethylenically unsaturated polycarboxylic acid resin with a secondary transition point of -10 to 20°C, (b) an amino resin and an organic solvent were placed. After that, stir to mix thoroughly. Examples of organic solvents include methanol, ethanol, n-propanol, isopropanol, n-
Alcohols such as -butanol, isobutanol, sec-butanol, t-butanol, pentanol, etc., cellosolves such as methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, sec-butyl cellosolve, etc. are used. The amount of organic solvent in the electrodeposition coating composition depends on the secondary transition point and amount of the α,β-ethylenically unsaturated polycarboxylic acid resin. Generally, it is used in an amount of 1 to 5% by weight of the coating film-forming components. When the composition of the present invention is used as an electrodeposition coating, an organic amine and/or ammonia is added to make the α,β-ethylenically unsaturated polycarboxylic acid resin water-dispersible, and then deionized water is added to form an appropriate coating. Use after diluting to the resin solid content concentration. The ammonia or organic amine used to make the α,β-ethylenically unsaturated polycarboxylic acid resin water-dispersible includes ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, and monoisopropylamine. Alkylamines, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, dimethylamino, such as diisopropylamine, triisopropylamine, monobutylamines, dibutylamine acid and tributylamine, etc. alkanolamines such as ethanol and diethylaminoethanol etc., alkylene polyamines such as ethylene diamine, propylene diamine, diethylene triamine and triethylene tetramine etc., alkylene imines such as ethylene imine and propylene imine etc.
Examples include piperazine, morpholine, pyrazine and pyridine. Carbon black can be in the form of either powder or water dispersion. If it is a powder, it is mixed and dispersed in the electrocoating paint stock solution, and if it is an aqueous dispersion, it is added to the electrocoating paint stock solution or diluted electrocoating paint solution. Just mix. The electrodeposition coating composition of the present invention can be applied directly on a conventional electrodeposition coating line using the same method, and forms a uniform and beautiful satin-like coating film. Furthermore, the coating film obtained by electrodepositing the electrodeposition coating composition of the present invention has excellent adhesion to the object to be coated, and also has excellent coating film performance in salt water spray resistance, acid resistance, and alkali resistance. There is something. (Example) Examples will be shown below to more specifically explain the present invention. However, the present invention is not limited to these examples. All parts in the examples are by weight unless otherwise specified. [Synthesis Examples of Polycarboxylic Acid Resins A to F] Polycarboxylic acid resins A to F were prepared by copolymerizing the monomer compositions shown in Table 1 under the conditions shown below. In a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, 24 parts of butyl cellosolve, 30 parts of isopropyl alcohol, and 1.5 parts of azobisisobutylonitrile were charged as the monomer composition and organic solvent, and the mixture was stirred at reflux temperature for 6 hours. A polycarboxylic acid resin was prepared. The acid value and secondary transition point of the polycarboxylic acid resin are shown in Table 1.

[Table] Example Polycarboxylic acid resin 11 prepared in Synthesis Examples A to F
and 3 parts of melamine resin (trade name: Cymel 285J, manufactured by Mitsui Toatsu) in a container, add 2 parts of triethylamine, mix thoroughly, and then add deionized water to make an electrodeposition paint with a resin solid content of 10%. did. To 100 parts by weight of this electrodeposition paint, an aqueous dispersion of carbon black (trade name: SA Black G-2, manufactured by Mikuni Shikiryo Co., Ltd.) was added in the proportions shown in Table 2 to prepare a black electrodeposition paint. Experimental Example Using black electrodeposition paints, a steel plate treated with iron phosphate in each paint was connected as an anode, a stainless steel plate was connected as a counter electrode, and DC current was applied at a voltage of 60 volts for 2 minutes. Next, the steel plate was taken out of the paint, thoroughly washed with water, and baked at 90°C for 30 minutes. As shown in Table 2, the black electrodeposition paints I to N and C had a uniform and beautiful satin-like appearance. A paint film was formed.

【table】

[Table] (Effects of the Invention) As is clear from the results of the Examples and Experimental Examples described above, the electrodeposition paint prepared from the composition for a satin-like electrodeposition paint of the present invention has a uniform and beautiful appearance of the matte finish coating. The coating film was also excellent in adhesion, salt spray resistance, acid resistance, alkali resistance, etc.

Claims (1)

[Claims] 1 The coating film-forming components (a) have a secondary transition point of -10 to 20°C
(b) 5 to 95 parts by weight of an α,β-ethylenically unsaturated polycarboxylic acid resin and 95 to 5 parts by weight of an amino acid resin, or an aqueous emulsion of the mixture;
(c) A composition for a satin-like electrodeposition paint, which contains carbon black in an amount of 2.0 to 30% by weight based on 100 parts by weight of the coating film-forming component.