JPS6216228B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a metal coating material characterized by containing a mixture of a polyhydroxy polyether containing a tertiary carboxylic acid ester group in the molecule and an alkyl etherified methylolated amino resin as a main vehicle component. The present invention provides a new and effective composition. Polymeric epoxy resins are widely used because of their excellent adhesion to metals and corrosion resistance. However, in recent years, due to the desire to reduce weight, rationalize the painting process, and save resources, there has been a growing trend to omit or reduce the painting process or improve workability, and the demand for high-performance paints has gradually increased. Ta. On the other hand, in recent years, the production of so-called pre-coated metal, known as coil coating, has increased, and it is widely used as a material for prefabricated construction methods, such as colored galvanized iron and colored aluminum, contributing to mass production methods. Precoated metal is generally produced by pre-treating a coiled or cut metal material, generally a steel plate, and then applying a base paint and a top coat. By the way, the paints used for these, especially the base paints, must have workability and corrosion resistance that can withstand strong deformation and impact during cutting and bending, as well as adhesion to top coat paints, fast curing during baking, and economical efficiency. It is necessary that all of the above are present. In particular, base paint is generally 3
The conditions are extremely harsh as it is used with a thin film of ~10μ. Conventionally, as the base paint, a mixture of a polymeric epoxy resin such as Epotote YD-019 (Toto Kasei Co., Ltd.) with an epoxy equivalent of 2,400 to 3,300 g/eq and a butylated melamine resin is used as the main vehicle. I came. However, with this composition, the corrosion resistance and impact resistance of the bent portion were not satisfactory. An improved version of these points is a mixture of a phenoxy resin, which is considered a polymer type of epoxy resin, and a resin with a viscosity average molecular weight of 35,000, such as Phenotote YD-50 (Toto Kasei Co., Ltd.), and a butylated melamine resin. It is used as the main vehicle. However, in the case of this composition, since the main vehicle phenoxy resin has a high molecular weight, a large amount of solvent is required to lower the viscosity during coating, an expensive solvent is required to prevent pigment sedimentation, and the high molecular weight It has the disadvantage of poor adhesion to top coats containing polyester as the main vehicle. The present invention provides an effective metal coating material that improves the disadvantages of epoxy resins and phenoxy resins without sacrificing their advantages. The present invention uses a mixture of one or more of polyhydroxy polyether (A) containing a tertiary carboxylic acid ester group in the molecule and alkyl etherified methylolated amino resin (B) as the main vehicle. The objective is to provide a covering material that "Polyhydroxypolyether (A) containing a tertiary carboxylic acid ester group in the molecule" as used in the present invention
It is preferable to have a tertiary carboxylic acid ester group at the end of the molecule, such as the following. general formula R ₁ is a C ₃ to C ₁₄ alkyl group, R ₂ and R ₃ are lower alkyl groups such as methyl or ethyl, and R ₄ and R ₅ are 2
Hydrolic alcohol or dihydric phenol residue, n is 0
Indicates an integer between ~15. same as below. or Methods for producing the polyhydroxypolyether compound used in the present invention include a method of reacting a corresponding epoxy compound with a tertiary carboxy compound, and a method of reacting a corresponding epoxy resin and a bisphenol compound in a molar ratio such that the terminal end is phenol. It is obtained by reacting and then reacting tertiary carboxylic acid glycidyl ester. The "corresponding epoxy resin" used in the present invention may be any epoxy resin having an average of more than one substituted or unsubstituted glycidyl group in the molecule, and may be of the glycidyl ether type, glycidyl ester type, or glycidyl amine type. Any of these may be used, and aromatic, aliphatic, or heterocyclic ring-containing substances may also be used. In addition, conventionally known epoxy resins such as those described in "Handbook of Epoxy Resins" (written by Henry Lee and Chris Neville, published by McGraw-Hill Book Company, USA) can be used. Among the above epoxy resins, particularly preferred ones have an epoxy equivalent of 170 to 2100 g/eq.
It is synthesized from bisphenol A and epichlorohydrin. From the viewpoint of corrosion resistance, it is preferable that the main component is an epoxy resin containing an aromatic ring in the molecule. It is preferred to contain an aliphatic diepoxy or tertiary carboxylic acid ester so that the epoxy moiety obtained from bisphenol and epichlorohydrin is greater than the aliphatic moiety, that is, the aliphatic epoxy, aliphatic carboxylic acid, and the ester moiety. The reaction between the tertiary carboxylic acid and the epoxy resin is carried out in the presence of a catalyst. Preferred catalysts include tertiary amines such as benzyldimethylamine, triethylamine, and pyridine, quaternary ammonium salts, halogenated lithium alkyl alcoholates, sulfuric acid, phosphoric acid, organic sulfonic acids, and urea. The reaction between bisphenol and epoxy is also carried out in the presence of a known catalyst. The reaction of the present invention is carried out in the presence or absence of a solvent, but by using an inert solvent with a relatively high boiling point, the reaction can be carried out while lowering the viscosity within the system, and side reactions such as branching can be avoided. It is preferable to use a solvent in order to reduce the amount of heat. Solvents suitable for this purpose include xylene, solvent naphtha, cyclohexanone, isophorone, and the like. As the tertiary carboxylic acid and tertiary carboxylic acid glycidyl ester used in the present invention, tertiary acids such as neodecanoic acid, versadecic acid, and pentanoic acid can be used, and the corresponding tertiary carboxylic acid can be prepared from these acids by known methods. Glycidyl esters can be synthesized. The reason why the present invention is limited to tertiary carboxylic acids or glycidyl esters thereof is that aliphatic primary carboxylic acid ester groups generally have poor alkali resistance and water resistance, making them impractical. On the other hand, in the case of tertiary carboxylic acid esters, these properties hardly deteriorate compared to conventional ones. Furthermore, it is possible to incorporate tertiary carboxylic acid glycidyl ester as a modifier, but this does not have a very large molecular weight and causes a decrease in chemical resistance and impact resistance. The amino resin in the alkyl etherified methylolated amino resin (B) in the present invention may be any of melamine resin, urea resin, and benzoguanamine resin, or may be a co-condensation resin of two or more types. As component (B), butyl etherified methylolmelamine resin is particularly preferred. The blending ratio of the polyhydroxy polyether and amino resin of the present invention is 5 to 5 in terms of amino resin content.
40% preferably 15-30%. This crosslinking reaction between the polyhydroxypolyether and the amino resin may be carried out without a catalyst, but if necessary, a catalyst such as phosphoric acid, para-toluenesulfonic acid and its morpholine salt may be added. In order to make the present invention more effective, it is preferable to blend coloring pigments, anti-rust pigments, extender pigments and other auxiliary materials. In particular, the use of anticorrosive pigments such as zinc chromate, strontium chromate, and condensed aluminum phosphate is effective in improving corrosion resistance. The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. In addition, "part" in the example
All numbers are parts by weight. Example 1 Into the separable flask of 1, add epoxy equivalent
Epoxy resin made from bisphenol A and epichlorohydrin with a softening point of 98°C and 944.2g/eq.
377.7 parts, 70.6 parts of neodecanoic acid having an acid equivalent of 180.2 g/eq, and 112 parts of xylene were added and dissolved by heating. Triethylamine as a catalyst when the internal temperature is 100℃
Added 0.3ml. After reacting for 9.5 hours at a reaction temperature of 138-140°C, the acid value reached 2 or less and the reaction was completed. 80 g of cellosolve acetate was added to obtain a varnish with a non-volatile content of 70%. Example 2 Same as Example 1, epoxy equivalent 1921g/eq
288.2 parts of epoxy resin made from bisphenol A and epichlorohydrin, 26.5 parts of neodecanoic acid with an acid equivalent of 180.2 g/eq, 79 parts of xylene, and 0.3 ml of triethylamine were added and reacted at 145-150°C for 8 hours to give an acid value of 1.2. Therefore, it was diluted with cellosolve acetate to obtain a varnish with a non-volatile content of 60%. Comparative Example 1 Epoxy equivalent used in Example 1 944.2g/eq
A varnish was prepared in the same manner as in Example 1 using 472.1 parts of epoxy resin, 146 parts of dehydrated castor oil fatty acid having an acid equivalent of 292 g/eq, 155 parts of xylene, and 0.3 ml of triethylamine. Example 3 Bisphenol A with epoxy equivalent weight 187.3 g/eq
and liquid epoxy resin from epichlorohydrin
218.3 parts, bisphenol A 177.1 parts, solvent naphtha 99 parts, lithium hydroxide 20ppm as catalyst
was added and reacted at 160°C for 3 hours. Next, 104.6 parts of versadectic acid glycidyl ester with an epoxy equivalent of 269.1 g/eq was added and reacted at the same temperature for 7 hours, and then diluted with solvent naphtha/cellosolve acetate (1/1) to a nonvolatile content of 60% to prepare a varnish. did. Example 4 Using the same liquid epoxy 374.6 parts, bisphenol A 342 parts, and versadectic acid glycidyl ester 269.1 parts as in Example 3, synthesis was carried out under the same conditions as in Example 3 to obtain a varnish with a non-volatile content of 60%. Example 5 Using the same liquid epoxy (136.8 parts), bisphenol A (166.6 parts), and versadectic acid glycidyl ester (196.6 parts) as in Example 3, synthesis was carried out under the same conditions as in Example 3 to obtain a varnish with a non-volatile content of 60%. Example 6 281 parts of the liquid epoxy resin of Example 3, 228 parts of bisphenol A, 200 ppm of 2-ethyl-4-methylimidazole, and 127 parts of solvent naphtha were heated at 160°C.
React for 3 hours, then add trimethylolpropane triglycidyl ether with an epoxy equivalent of 145 g/eq.
112 parts were added and reacted for 5 hours. Further, 85.6 parts of neodecanoic acid was added and reacted for 5 hours to obtain a varnish with a non-volatile content of 60% in the same manner as in Example 3. Example 7 139.1 parts of the liquid resin used in Example 3, 188.7 parts of bisphenol A, 20 ppm of lithium hydroxide, and 82 parts of solvent naphtha were added, and after reacting at 150°C for 3 hours, polyethylene glycol diglycidyl with an epoxy equivalent of 170 g/eq was obtained. Add 126.2 parts of ether and 30 parts of solvent naphtha and react at the same temperature for 4 hours. Next, add 45.9 parts of glycidyl glycidyl ester and react for 8 hours.
Get 50% varnish. Comparative Example 2 A varnish was prepared by adding 70 parts of an epoxy resin made from bisphenol A and epichlorohydrin with an epoxy equivalent of 2500 g/eq and a softening point of 132°C, 30 parts of glycidyl versadic acid ester, and 67 parts of cellosolve acetate/xylene (1:1). It became. Comparative Example 3 50 parts of an epoxy resin made from bisphenol A and epichlorohydrin having an epoxy equivalent of 2500 g/eq and a softening point of 132°C, 25 parts of solvent naphtha, and 25 parts of cellosolve acetate were added to form a varnish. Next, the physical properties of the varnishes obtained in the above Examples and Comparative Examples will be shown.

【table】

[Table] In order to evaluate the performance of the varnish obtained in the above example as a base paint, it was made into a paint using the following formulation. Resin of A-J formulation examples and comparative examples * 85 parts Butylated melamine resin * (commercial product) 15〃 Titanium oxide (rutile type) 50〃 Zinc chromate ZTO 50〃 Bentone #38 (manufactured by NL Industries) 1 part Cellosolve acetate/xylene = 1/1 Combination of K and L as appropriate Resin of examples and comparative examples * 70 parts Butylated melamine resin * 30〃 Strontium chromate 100〃 Bentone #38 2〃 Cellosolve acetate/xylene = 1/1
135〃 *Amount converted to solid content After dispersing the pigment at a solid content concentration of 50% to 60%, it was diluted as appropriate during painting and applied with a bar coater. The top coat paint is a commercially available polyester-based paint (Alumatex P-646 manufactured by Mitsui Toatsu Chemical Co., Ltd. and Yuban manufactured by the same company).
20SE60) was used. Painting conditions (1) Material: 0.3mm thick zinc phosphate chemical conversion treated galvanized steel sheet (2) Film thickness: Primer/top coat 5μ/15μ (3) Baking: 2 coats 2 bakes 230℃ x 60 seconds (Surface temperature)

【table】

[Table] The indications in the table are: ◎: Very good, 〇: Excellent, △: Average, ×: Poor, XX: Very poor.
Also, blister display is based on the Japan Paint Inspection Association standards.

Claims (1)

[Claims] 1. A metal coating material comprising a mixture of a polyhydroxy polyether containing a tertiary carboxylic acid ester group in the molecule and an alkyl etherified methylolated amino resin as a main vehicle component.