JPS637226B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel electrodeposition coating composition, and more specifically to a novel cation composition that exhibits excellent performance in terms of throwing power during coating, coating film smoothness, adhesion, flexibility, corrosion resistance, water resistance, etc. The present invention relates to a composition for electrodeposition coating. Various studies have been carried out on cationic electrodeposition paints, and one example is epoxy resins that do not have olefinic unsaturated bonds, such as glycidyl ether type epoxy resins synthesized from bisphenol A and epichlorohydrin. After reacting a primary or secondary amino compound, it is neutralized with an acid to form a water-soluble or water-dispersible amine salt. A method of curing with a crosslinking agent such as an isocyanate compound has been developed (for example, Japanese Patent Publication No. 49-23807, Japanese Patent Application Laid-Open No. 48-51924, etc.). According to this method, it is possible to obtain a coating film that exhibits far superior performance in terms of corrosion resistance compared to anionic electrodeposition paints, but on the other hand, it has poor throwing power and smoothness of the coating film during electrodeposition coating. , flexibility and adhesion, and improvements have been desired. Recently, oils containing double bonds in their molecules (e.g. natural drying oils, liquid diene polymers, etc.) have been epoxidized, and the resulting epoxides have been converted into water-soluble or A method for producing a dispersible amine salt has also been developed (Japanese Patent Application Laid-Open No. 16048/1983). In this case, since double bonds that do not participate in the epoxidation reaction remain, there is an advantage that the material can be cured by an oxidative curing reaction without using a special crosslinking agent. However, although the coating film obtained by this method has excellent flexibility, it requires a high baking temperature, has low hardness, and has poor throwing power, adhesion, water resistance, alkali resistance, etc. It could not be said that it was sufficient in terms of both aspects. The inventors of the present invention conducted intensive studies to improve these drawbacks of the conventional technology, and as a result, discovered that a remarkable synergistic effect can be obtained by using a common epoxy resin and a specific liquid polymer epoxide in combination.
The present invention has now been completed. That is, an object of the present invention is to provide a novel composition for cationic electrodeposition paint that has excellent throwing power and can provide a coating film that is excellent in adhesion, flexibility, corrosion resistance, and smoothness. The purpose of the present invention is to react an epoxy resin component with a basic amino compound to open at least a portion of the epoxy group, and then neutralize it with an acid to produce a water-soluble or water-dispersible resin. In an electrodeposition coating composition containing as a vehicle component, the epoxy resin component is (a) an epoxy resin having no olefinic double bond and (b) a liquid butadiene-based polymer containing 15% or more of 1.4-bonds. This is achieved by using a mixture of epoxides. In the present invention, as an epoxy resin component,
The two components (a) and (b) above are used. Of these (a)
Any component may be used as long as it does not contain olefinic unsaturated bonds and has two or more epoxy groups per molecule. Specific examples include epoxy resin obtained from bisphenol A and epichlorohydrin, hydrogenated Epoxy resins obtained from bisphenol A and epichlorohydrin, polyglycidyl ethers of novolac resins and similar polyphenolic resins, ethylene glycol,
propylene glycol, diethylene glycol,
Examples include polyglycidyl ethers of polyhydric alcohols such as glycerin, and acrylic copolymers having epoxy groups. On the other hand, as component (b), an epoxide obtained by epoxidizing a liquid butadiene-based polymer is used. The liquid butadiene-based polymer used is a homopolymer of butadiene or a copolymer of butadiene and other comomates such as isoprene, 1,3-pentadiene, styrene, etc., and contains 1,4-bonds in an amount of 15% or more, preferably 20% or more. . In this case, if the 1.4 bond is less than 15%, the flexibility, smoothness, adhesion, corrosion resistance, etc. of the coating film will be poor, and as the butadiene unit content in the polymer decreases, the throwing power, flexibility, etc. Since this results in poor adhesion, corrosion resistance, etc., it is appropriate that the butadiene unit content in the copolymer be at least 50% by weight, preferably at least 70% by weight. Other properties of liquid butadiene-based polymers are not particularly limited, but usually the number average molecular weight
300-10000, preferably 500-5000 Iodine value 100-
500, preferably 150 to 480,
The molecular terminal may be either non-functional or terminal-functional having a hydroxyl group or a carboxyl group. The epoxidation reaction of a liquid butadiene-based polymer may be carried out according to a conventional method, and can be easily carried out, for example, by using hydrogen peroxide or a peracid. At that time, the degree of epoxidation of the double bonds in the polymer is as follows: the oxirane oxygen content is 1.5 to 15% by weight,
Preferably, it is appropriate to set it as 3 to 13% by weight,
If the oxirane oxygen content is too low, water solubility or water dispersion will be insufficient, and if it is too high, the curing reactivity of the coating material will decrease and it will not be able to exhibit sufficient performance. Also, during the epoxidation reaction, it is possible to convert some of the generated epoxy groups into hydroxyl groups and acyloxy groups, and methods for doing so include:
For example, hydrogen peroxide can be mixed with formic acid, acetic acid, propionic acid,
An example is a method of adding and reacting simultaneously with an organic monocarboxylic acid such as benzoic acid. When performing this reaction, a mineral acid such as sulfuric acid is present, and two hydroxyl groups are introduced into the double bond at the same time.
It can also be converted into glycol. It is also possible to convert the added acyloxy group into a hydroxyl group by hydrolyzing it with an alkali catalyst and convert it into α-glycol. When a hydroxyl group or an acyloxy group is introduced using an epoxidation reaction in this way, it is appropriate to adjust the oxirane oxygen content to 1.5 to 15% by weight. The above (a) component constituting the epoxy resin component and the above
The usage ratio of component (b) is usually 97 to 3% by weight, preferably 95 to 5% by weight, and 3 to 97% by weight, preferably 5 to 95% by weight of the latter. A coating film with significantly improved running properties and adhesion and excellent flexibility, water resistance, and corrosion resistance can be obtained. In the present invention, a reaction product in which at least a portion of the epoxy group is ring-opened is formed by reacting the epoxy resin component with a basic amino compound. The basic amino compound to be subjected to the reaction is mainly a compound having a primary or secondary amino group, such as a) propylamine,
b) mono- and dialkylamines such as butylamine, diethylamine, dipropylamine; b) mono- and dialkanolamines such as ethanolamine, propanolamine, diethanolamine, dipropanolamine; c) alicyclics such as cyclohexylamine, pyrrolidine, morpholine. monoamines of the formula d) polyalkylene polyamines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, propylenediamine, dipropylenetriamine, butylenediamine, e) N-aminoethanolamine, diethylethylenediamine, Examples include polyamines such as diethylaminopropylamine, hydroxyethylaminopropylamine, piperazine, N-methylpiperazine, and N-aminoethylpiperazine. As a special example, amino acids having a tertiary amino group can also be used. Among these, water-soluble aliphatic amines are particularly preferred. The reaction between the epoxy resin component and the basic amino compound starts even when they are mixed at room temperature, but in order to complete the reaction, the reaction is preferably performed at 50-170°C.
It is best to heat it to 70-150℃. The amount of amino compound used in the reaction may be sufficient to solubilize or disperse the reaction product in water when finally treated with the acid, and the reaction between the two forms the epoxy resin component. Component (a), component (b) and the basic amino compound may be simultaneously placed in a reaction vessel, or the reaction between the component (a) and the basic amino compound, and the reaction of the component (b) The reactions between the components and the basic amino compound may be carried out independently. Further, a solvent may be added to reduce the viscosity of the reaction mixture and facilitate the reaction, but in this case, it is preferable to distill off the unreacted amine and the solvent by vacuum or extraction after the reaction. The reaction product of the epoxy resin component and the basic amino compound thus obtained is then converted into an organic compound such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, hydroxyacetic acid, phosphoric acid, and hydrochloric acid according to a conventional method. It is made into a water-soluble or water-dispersible salt by neutralization with an acid or an inorganic acid. At this time, the reaction product of component (a) in the epoxy resin component and the basic amino compound and the reaction product of component (b) in the epoxy resin component and the basic amino compound are separately neutralized and then mixed. Alternatively, both reaction products may be mixed and neutralized simultaneously. In addition, the amount of acid required for neutralization is preferably at least the amount necessary to solubilize or disperse the reaction product in water, and less than or equal to the equivalent amount of amino groups in the reaction product. It is appropriate that the pH of the system is 3 to 8, preferably 5 to 7. In addition, in the present invention, it is necessary to blend a crosslinking agent according to a conventional method, and specific examples thereof include water-soluble or water-dispersible melamine resin, water-soluble or water-dispersible phenol resin, and blocked isocyanate compound. Examples include. Examples of suitable melamine resins are urea, bensoguanamine or reaction products of melamine and aldehydes, which may also be etherified with alcohols. Specific examples of suitable phenolic resins include reaction products of phenols and aldehydes, which may be initial condensates or polymers as long as they contain reactive methylol groups. The amount of these melamine resins or phenolic resins to be used is selected as appropriate, and is usually 5 to 40% by weight, preferably 8% by weight based on the total binder solid weight.
~30% by weight. On the other hand, when using a blocked isocyanate compound (i.e., a polyisocyanate compound having an average of one or more blocked isocyanate groups and an average of one or less free isocyanate groups in one molecule) as a crosslinking agent, It is preferable to allow the reaction product of the epoxy resin component and the basic amino compound to react in advance prior to the crosslinking reaction, and this method provides a particularly superior effect compared to the use of other crosslinking agents. can get. In the present invention, an electrodeposition coating composition can be obtained by blending other formulation examples in accordance with a conventional method with a binder component consisting of a water-soluble or water-dispersible salt and a crosslinking agent as described above. In this case, the concentration of the binder component is usually 3 to 30% by weight, and color pigments such as titanium white and carbon black, anticorrosion pigments made of metal compounds such as chromium, lead, barium, and aluminum, and even clay. ,
It is appropriate to mix extender pigments such as talc and calcium carbonate in an amount of 400 parts by weight or less per 100 parts by weight of the binder component. Other anti-aging agents, stabilizers, etc. may also be added if desired. The cationic electrodeposition coating composition of the present invention thus prepared has excellent throwing power during electrodeposition, and also exhibits excellent performance in the flexibility, smoothness, adhesion, and corrosion resistance of the coating film. The present invention will be explained in more detail with reference to Examples below. Note that all parts and percentages in Examples and Reference Examples are based on weight. Reference Example Test A; Dissolve 500 parts of bisphenol A type epoxy resin (trade name Epicote 1001, manufactured by Ciel Chemical Co., Ltd.) having an epoxy equivalent of 500 in 250 parts of butyl acetate,
63 parts of diethanolamine was gradually added dropwise to this solution, and after the addition was completed, the reaction was carried out at 80° C. for 2 hours. Next, 168 parts of tolylene diisocyanate (a mixture of 80% 2.4-tolylene diisocyanate and 20% 2.6-tolylene diisocyanate) and n-
246 parts of blocked isocyanate prepared by reacting 78 parts of butanol at 80°C or lower for 2 hours was added, and after the reaction was carried out at 70 to 90°C for 2 hours, the solvent was distilled off under reduced pressure to form a pale yellow transparent blocked polyester. A reaction product containing isocyanate groups was obtained. Sample B: Liquid polybutadiene (number average molecular weight 1100, viscosity at 30°C 800 centipoise, 53% cis-1,4 bond content, 9% trans-1,4 bond content, and 38% 1,2 bond content by infrared absorption spectrum)
300 parts were dissolved in 300 parts of toluene, and 9 parts of sodium acetate was added thereto. After slowly adding 500 parts of peracetic acid (41%) to this mixture over 1 hour, the mixture was further reacted at 30°C for 4 hours. Thereafter, the reaction product was washed with water, an aqueous solution of caustic soda, and water in this order, and finally the solvent was removed under reduced pressure to obtain epoxidized polybutadiene with an oxirane oxygen content of 10.1%. 52 parts of diethanolamine and 10 parts of xylene were mixed with 100 parts of this epoxidized polybutadiene and reacted at 150° C. for 9 hours to obtain a product with no oxirane oxygen content. Sample C: Instead of the polybutadiene used in the production of sample B, commercially available liquid cis-1,4-polybutadiene (trade name Polyoil 110, manufactured by Hyulus, number average molecular weight 1600, cis-1,4 = 74%,
The reaction was carried out in the same manner as in Sample B except that trans-1,4 (25%, vinyl = 1%) was used to obtain epoxidized polybutadiene containing oxirane and oxygen at 7.8%. This epoxidized polybutadiene and diethanolamine were reacted to obtain an adduct containing 0.5% residual oxirane oxygen. Sample D: Commercially available epoxidized 1,2-polybutadiene (manufactured by Nippon Soda Co., Ltd., number average molecular weight 1000, vinyl 90
1,2-polybutadiene (1,2-polybutadiene epoxidized with an oxygen content of 7.7%) was reacted with diethanolamine to obtain an adduct with a residual oxirane oxygen content of 0.7%. Sample E: Liquid polypentadiene (number average molecular weight 3200, iodine value
347, cis (1,4 + 1,2) = 75.9%, trans (1,4 + 1,2) = 24.1%) was used in place of the polybutadiene in Sample B. 9.0
% epoxidized product, which was then reacted with diethanolamine to give a residual oxirane oxygen content of 0.3
% adduct was obtained. Sample F: Commercially available epoxidized soybean oil (manufactured by Asahi Denka Kogyo Co., Ltd.,
100 parts of oxirane (5% oxygen) was reacted with diethanolamine under the same conditions as in the production of Sample B to obtain an adduct with no residual oxirane oxygen. Sample G: A reaction product was obtained in exactly the same manner as Sample A except that blocking isocyanate was not used. Sample H: 250 parts of sample G and 250 parts of sample B were mixed with 200 parts of toluene.
168 parts of tolylene diisocyanate and n-
After adding 246 parts of blocked isocyanate prepared by reacting 78 parts of butanol and reacting at 70 to 90°C for 2 hours, the solvent was distilled off under reduced pressure to obtain a yellow transparent reaction product containing blocked isocyanate groups. Ta. Example 1 (1) Preparation of water-soluble varnish 20 parts of butyl cellosolve was added to 100 parts of sample A, sample B, or a mixture of both, and lactic acid corresponding to 0.8 equivalents of amino groups was added and mixed well. Add distilled water to make solid concentration 40%, pH 3-7
A water-soluble or water-dispersible varnish was prepared. (2) Preparation of pigment dispersion 100 parts of water-soluble varnish prepared in (1), titanium oxide
25 parts, lead oleate 1 part, carbon black 0.3
The components were mixed and stirred for 1 hour using a pigment disperser to obtain a paste-like dispersion. (3) Preparation of paint composition 126 parts of the dispersion prepared in (2) and 150 parts of the water-soluble varnish obtained in (1) were mixed, and distilled water was added to adjust the solid content.
I made a 10% paint with a pH of 3 to 7. (4) Electrodeposition conditions The composition prepared in (3) was used as an electrodeposition solution, and a dull steel plate treated with iron phosphate was used as a cathode at a bath temperature of 25℃ and a distance between electrodes of 7cm under a voltage of 70 to 200V. Electricity was applied for a minute, and after the electricity was applied, the test piece coated with cathode electrodeposition was taken out, washed with water, air-dried, and then baked at 180°C for 30 minutes. The various performances of the obtained film were measured, and the first
The results shown in the table were obtained.

[Table] The results show that when a polybutadiene epoxy compound is blended with a normal epoxy resin, a remarkable improvement effect can be obtained in both electrodeposition coating performance and coating film performance. Example 2 An experiment was conducted in exactly the same manner as in Example 1, except that a mixture of equal amounts of Sample A and Samples C to F was used. The results are shown in Table 2.

[Table] This result shows that even if 1,2-polybutadiene, polypentadiene, or epoxidized soybean oil is used in combination, the synergistic effect as achieved in the present invention cannot be achieved. Example 3 The same experiment as in Example 1 was conducted on Sample H to obtain a paint having a pH of 5.4. This paint was then painted at 180V and baked at 180°C for 30 minutes to evaluate its performance. As a result, the throwing power,
21.5cm, film thickness 20μ, excellent smoothness, pencil hardness
2H, Erichsen test of 8 mm or more, 100% pass of tape peeling adhesion test of cross cut section after extrusion of 3 mm Excelin, no blisters were observed up to 500 hours in water resistance test, rust width was 1 mm even after 500 hours in salt spray test. Ta. Example 4 After mixing 50 parts of sample G and 50 parts of sample B, a water-soluble varnish with a solid content concentration of 40% and a pH of 4.9 was prepared according to Example 1, and water-soluble melamine resin was added to 100 parts of solid content of the varnish. (Cymel 303 manufactured by American Cyanamid Co.) was added, and the other operations were as in Example 1.
The experiment was conducted according to the method of
The temperature was 190V, and baking was carried out at 190℃ for 30 minutes). As a result, the throwing power was 19.5cm, the film thickness was 22μ, excellent smoothness, the pencil hardness was F, the Erichsen test was 8mm or more, and the tape was not peeled off after extruding the cross-cut part in a grid pattern by 3mm with Erichsen. The coating passed 100% in adhesion, no blisters were observed in the water resistance test up to 500 hours, and the rust width was 1.5 mm even after 500 hours in the salt spray test, indicating that the coating was very good.

Claims (1)

[Claims] 1. A binder component is a water-soluble or water-dispersible salt obtained by reacting an epoxy resin component with a basic amino compound to open at least a portion of the epoxy group, and then neutralizing it with an acid. In the electrodeposition coating composition containing as the epoxy resin component,
A composition for electrodeposition paint characterized by using a mixture of (a) an epoxy resin having no olefinic double bonds and (b) a liquid butadiene-based polymer epoxide containing 15% or more of 1.4-bonds. thing. 2 The epoxy resin component is 97 to 3% by weight of the component (a) above.
The composition according to claim 1, which is a mixture of 3 to 97% by weight of component (b).