JPH0535192B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating method using a coating composition with excellent adhesion, impact resistance, chemical resistance, and salt spray resistance. Traditionally, epoxy resins have been widely used in paints, electricity, and other products due to their excellent mechanical, chemical, and electrical properties.
Used in civil engineering, architecture, and adhesive fields. Among these uses, coatings for metals are used for coatings because of their excellent adhesion to substrates, chemical resistance, salt spray resistance, moisture resistance, impact resistance, abrasion resistance, flexibility, and gloss. It is used as a resin component in paints, metal and concrete primers, etc. However, in recent years, the performance requirements for these applications have become more sophisticated, and further drastic improvements in performance have been desired. In view of these circumstances, the present inventors have made extensive studies to improve the basic properties of coating compositions using bisphenol A-type epoxy resins that are suitable for a wide range of applications. By using a coating composition containing an epoxy resin in which part of the A skeleton is replaced with dihydroxybenzene, the adhesion of the coating film to the substrate can be improved.
We have completed the present invention by discovering that basic physical properties such as impact resistance, chemical resistance, and salt spray resistance can be greatly improved. That is, the present invention provides (A) general formula [] (In the formula, R ₁ is a bisphenol A residue and R ₂ is a dihydroxybenzene residue. n is 1 to 2
indicates an integer. ) epoxy resin,
and (B) a coating method using a coating composition containing a curing agent and, if necessary, a curing accelerator. The epoxy resin represented by the above general formula used in the present invention is, for example, (In the formula, R ₁ is as described above.) A diepoxy compound represented by the general formula (In the formula, R ₂ is as described above) is reacted appropriately in the presence of a catalyst, if necessary. It can be prepared by reacting at a temperature of 60°C to 160°C. As dihydroxybenzene, resorcinol, hydroquinone, and catechol are used. Among these, resorcinol is particularly preferred. In addition, the number of repeating units n is
Must be 12 or less. That is, n is
If it exceeds 12, it is disadvantageous in terms of manufacturing or work. Therefore, in the present invention, the number of repeating units must be 1 to 12. In addition, the coating composition of the present invention may optionally contain known epoxy resins, such as polyglycidyl ethers of polyhydric phenols or polyhydric alcohols, polyglycidyl esters obtained from polycarboxylic acids, or glycidyl ether esters. Furthermore, a glycidylamine compound obtained from a polyamine may also be contained. (B) As the curing agent, a conventionally known epoxy resin curing agent is used. For example, aliphatic polyamines such as polyethylene polyamine and aminoethylpiperazine, polyamide resins obtained from dimer acid or trimer acid and ethylene amines, aromatic polyamines such as phenylene diamine and diaminodiphenylmethane, or the above compounds and known epoxy Examples include adducts with compounds, so-called modified products, acid anhydrides such as phthalic anhydride, methyltetrahydrophthalic anhydride, pyromellitic anhydride, and methylnadic anhydride, and dicyandiamide. As curing accelerators, tertiary amines such as 2,4,6-tris(dimethylaminomethyl)phenol and N,N-dimethylbenzylamine, imidazoles, BF _8s , and 1,8-diazabicyclo Known curing accelerators such as (5,4,0) undecene-7 (DBU) or salts thereof are exemplified. The amount of these curing agents or curing accelerators used is not particularly limited and falls within the range commonly used. In the case of a curing agent, it is used in an amount of 0.5 to 2.0 equivalents based on the epoxy equivalent of the epoxy resin. Regarding curing accelerators, epoxy resin (a)
It is used in a range of 0.1 to 10 parts by weight per 100 parts by weight. The coating composition used in the present invention may contain pigments, fillers, extenders, reactive diluents, flexibility agents, solvents, plasticizers, viscosity modifiers, colorants, etc. as necessary. No problem. In a coating method using such a coating composition, the coating composition is dissolved in a solvent or the like and brushed onto the object to be coated.
Apply with a roller or spray method and cure at room temperature or by heating, or use dry blending or melt blending without turning into a solution with a solvent, etc. as a powder coating and fluidly immerse it on the object to be coated. Apply by method, electrostatic spray method, etc. at 120°C to 130°C.
There is a method of curing by heating to ℃. Examples of the object to be coated include iron, aluminum, aluminum alloy, brass, copper, zinc, plastic, wood, and concrete. As described above, the coating method of the coating composition according to the present invention can provide a coating film with excellent adhesion, impact resistance, chemical resistance, and salt spray resistance, and can be used as a coating material for metals, a primer for metals, Can be used as a lacquer for metal substrates, etc. The present invention will be explained below with reference to Examples. In addition,
In the examples, parts indicate parts by weight. Synthesis Example 1 Diglycidyl ether of bisphenol A (epoxy equivalent: 187 g/eq, viscosity: 12,700 CPat, 25°C) was placed in a reactor equipped with a stirrer, a thermometer, and a reflux condenser.
100 parts, 165 parts of resorcin, and 397 parts of methyl isobutyl ketone (hereinafter abbreviated as MIBK).
After adding 0.4 parts of tri-n-butylamine at the same temperature, the mixture was heated to reflux temperature and kept under reflux for 7 hours. Then, MIBK was distilled off from the reaction mixture. Softening point 94
An epoxy resin with an epoxy equivalent of 950 was obtained. Synthesis Example 2 Diglycidyl ether of bisphenol A (epoxy equivalent 187g/eq, viscosity 12700CPat25℃) 908
1 part, 200 parts of hydroquinone, 474 parts of MIBK, and 0.5 part of tri-n-butylamine, and kept warm for 5 minutes.
An epoxy resin having a softening point of 95°C and an epoxy equivalent of 940 was obtained in the same manner as in Synthesis Example 1 except for the time. Synthesis Example 3 Diglycidyl ether of bisphenol A (epoxy equivalent 187g/eq, viscosity 12700CPat25℃) 908
Department, Catechol 196 Department, MIBK 478 Department and Tree n
- A softening point of 88 was carried out in the same manner as in Synthesis Example 1, except that 0.5 part of butylamine was used and the incubation time was 11 hours.
An epoxy resin with an epoxy equivalent of 950 was obtained. Comparative Example 1 Diglycidyl ether of bisphenol A (epoxy equivalent 187g/eq, viscosity 18700CPat25℃) 992
An epoxy resin with a softening point of 101°C and an epoxy equivalent of 960 was obtained in the same manner as in Synthesis Example 1, except that 430 parts of bisphenol A, 609 parts of MIBK, and 0.5 parts of tri-n-butylamine were used, and the incubation time was 6 hours. Ta. Comparative Example 2 773 parts of diglycidyl ether of resorcin (epoxy equivalent: 131 g/eq, 433 CPat 25°C), 264 parts of resorcin, 440 parts of MIBK, and 0.6 part of tri-n-butylamine were used, except that the incubation time was 6 hours.
In the same manner as in Synthesis Example 1, an epoxy resin having a softening point of 88°C and an epoxy equivalent of 1010 was obtained. Example 1 143 parts of a 70% methyl ethyl ketone solution of the epoxy resin obtained in Synthesis Examples 1 to 3 and Comparative Example 1 and 13 parts of Sumikiure P-725 (Sumitomo Chemical Co., Ltd., polyamide resin, amine value 300 mgKOH/g) , and 25 parts of toluene, and applied it to a mild steel plate (JISG3141SPCC-D) using a brush.
After curing for 7 days at room temperature, the physical properties of the coating film were evaluated. The results are shown in Table-1. Example 2 In Example-1, Syoamine was used instead of Sumikiure-P-725, which is an epoxy resin curing agent.
The physical properties of the coating film were evaluated in the same manner except that 5.7 parts of 9000 (manufactured by Showa Denko, modified aliphatic polyamine, amine value 530 mgKON/g) was used. The results are shown in Table-2.

【table】

【table】

[Table] Example 3 143 parts of the 70% methyl ethyl ketone solution of the epoxy resin obtained in Synthesis Example 1 and Comparative Examples 1 and 2,
S-tar LE (Kinki Tar Co., Ltd. product, anhydrous tar, viscosity
1100~1800CP/25℃) and 100 copies of Sumikiur.
ML-2 (Sumitomo Chemical, modified aromatic polyamine,
A mixture of 14.7 parts of amine value 230 mg/KOH/g) and 12 parts of ethyl cellosolve was applied to a mild steel plate (JISG3141SPCC-D) using a roller, and after curing at room temperature for 7 days, the physical properties of the coating film were evaluated. .
The results are shown in Table-3.

【table】

[Table] Example 4 100 parts of the epoxy resin obtained in Synthesis Example 1 and Comparative Example 1, 4 parts of dicyandiamide, and Kyuazole C ₁₁ Z (Shikoku Kasei Co., Ltd. product, 2-undecylimidazole, melting point 73°C) 0.3 parts of titanium oxide, 45 parts of titanium oxide, and Modaflow (Monsanto, USA).
After melt-kneading 0.1 part of Flow Control Agent) at 90°C for 5 minutes using a heating roll, the mixture was pulverized into 150 meshes to obtain a powder coating composition. This powder coating composition was applied using an electrostatic spray method using an electrostatic powder coating machine manufactured by GEMA at an applied voltage of 70 KV and a powder discharge rate of 100 g/min.
It was applied to a mild steel plate under the following conditions and heated at 180°C for 15 minutes to obtain a coating film. The physical properties of this coating film were evaluated. The results are shown in Table-4. Example 5 In Example-4, 60 parts of the epoxy resin obtained in Synthesis Example 1 and Sumiepoxy ESA-011 (manufactured by Sumitomo Chemical Co., Ltd., bisphenol A type epoxy resin) were used instead of the epoxy resin obtained in Synthesis Example 1. The physical properties of the coating film were evaluated in the same manner except that a mixture of 40 parts of epoxy equivalent (epoxy equivalent: 480 g/eq) was used. The results are shown in Table-4. Example 6 In Example-4, instead of the epoxy resin obtained in Synthesis Example 1, 70 parts of the epoxy resin obtained in Synthesis Example 1 and Sumiepoxy ESCN-220HH (Sumitomo Chemical Co., Ltd., 0-cresol novolak type) were used. The physical properties of the coating film were evaluated in the same manner except that a mixture of 30 parts of epoxy resin (epoxy equivalent: 220 g/eq) was used. The results are shown in Table-4.

[Table] From the above examples, it is clear that the coating method according to the present invention provides coating films with excellent adhesion, impact resistance, chemical resistance, and salt spray resistance.

Claims (1)

[Claims] 1 (A) General formula (In the formula, R ₁ is a bisphenol A residue and R ₂ is a dihydroxybenzene residue. n is 1 to 2
indicates an integer. ) epoxy resin,
and (B) a coating method using a coating composition containing a curing agent and, if necessary, a curing accelerator.