JPH01315475A - Production of cation-type electrodeposition paint - Google Patents

Abstract

PURPOSE:To obtain the subject paint with an excellent electrodeposition efficiency capable of forming a coating film excellent in corrosion resistance by adding a specified amount of water to a neutralized resin for a cation-type electrodeposition paint and dispersing the resin in water with stirring. CONSTITUTION:A neutralizing agent such as acetic acid or propionic acid is added to an organic solution of a resin for a cation-type electrodeposition paint to form a neutralized material. Water is then added to the neutralized material in an amount of 1-50 pts.wt. based on 100 pts.wt. solid resin component in the cation-type electrodeposition paint. The resultant mixture is stirred and then dispersed into water to provide the objective paint.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing a cationic electrodeposition paint.

(Prior art and its section M) Cationic rMIIi paints have excellent corrosion resistance and form a coating film on metal materials, and have good coverage and uniform coating on complex metal products or parts. Because it forms a film, it has been widely applied in fields related to automobiles, electrical equipment, and building materials.

In the cationic electrodeposition paint, it is widely known that hard (1') epoxy resins such as bisphenol to shrimp chlorohydrin type epoxy resins have excellent corrosion resistance and adhesion, and primary epoxy resins A method is already known in which an adduct of a resin and a primary or secondary amine is neutralized with an acid and dispersed in water. contains particles with a relatively large particle size, and the coarse particles settle at the bottom of the electrolyte paint bath, clogging the filter and causing line troubles, and causing horizontal problems of the object to be coated. There is a certain point that it settles in some parts, and baking may cause poor smoothness of the coating film.

As a method to improve such drawbacks, (1) increasing the amount of primary or secondary amine added to the epoxy resin;
<'bait, increasing the amount of neutralizing agent, (3) using surfactant, etc. have been conventionally practiced.

However, in methods (1) and (3) above,
A coating film with poor corrosion resistance is formed, and (in method 2, the coulomb yield during TLl coating decreases, and the throwing power and anti-corrosion copper plate coating properties deteriorate, so that it is still difficult to obtain a satisfactory electric koma paint. It has not been done.

The present invention overcomes the above-mentioned problems and provides cationic type t, I
The aim is to provide the manufacturing of f-paints.

(Next means for solving awA) The present invention is a method for producing a cationic electronic paint, in which water is added to a neutralized product of a resin for cationic electrocoating paint to reduce the solid content of the resin in the cationic electronic paint to 100%. 1 to 151 parts by weight
It relates to a method for producing a cationic electrolyte paint, which comprises adding i part of the compound and then dispersing it in water.

Examples of the cationic electrodeposition coating resin used in the present invention include cationic resins that have a water-dissociable cationic group in the resin and have been conventionally used in the field of cationic electrical coatings. Examples of the cationic resin include adducts of polyepoxide with primary mono- and polyamines, secondary polyamines, or mixed primary and secondary polyamines (see, for example, U.S. Pat. No. 3,984,299); polyepoxides; Once ketiminated with a secondary amino group having a primary amino group,
adducts with class mono- and polyamines (e.g. U.S. Pat.
．． 017.4388); a reaction product obtained by etherification of a polyepoxide with a hydroxyl compound having a ketiminated primary amino group (for example, JP-A-59-4
3013); cationic vinyl copolymer (see Publication No. 3013);
For example, see JP-A-61-293273) and their quaternary ammonium salts.

Among the above-mentioned polyepoxides, those which are particularly preferred from the point of view of price and anticorrosion properties have a number average molecular weight of at least 380, preferably 800 to 2.0 (in the range of 10) and an epoxy equivalent of 190 to 2,000, preferably 400 to 1.0 (10
Polyglycidyl ethers of polyphenols ranging from

The cationic resin used in the present invention has an amine value of 25 to 400, preferably 40 to 60. When the amine value is within this range, the dispersibility in water is excellent, the corrosion resistance of the resulting coating film is improved, and the electrodeposition efficiency is also good.

The cationic resin can be blocked with, for example, an alcohol and then cured with a polyisocyanate compound to form a l1-adhesive coating film.

The method for producing the cationic W-based paint of the present invention involves mixing a neutralized solution of the cationic resin in an organic solvent with a neutralizing agent or a blocked polyisocyanate compound before neutralization, without performing neutralization. After neutralization, a predetermined amount of water is added, stirred, and then this product is dispersed in water.

In addition to the above-mentioned method, it can also be carried out by adding a predetermined amount of water to a neutralized solution of an organic core solution of a cationic resin, and then dispersing a mixture of a blocked polyisocyanate compound in water.

As the organic solvent, any organic solvent that is inert to the cationic resin, dissolves or disperses the resin, and exhibits hydrophilicity can be used without any limitations. Specifically, organic solvents such as N, TTF alcohol type, ester type, ether type, ketone type, etc. may be mentioned.In addition to the above organic solvents, hydrophobic organic solvents such as aromatic hydrocarbon type, hydrophilic organic solvents, etc. Can be used in conjunction with The blending ratio of the organic solvent is usually about 25 to 60 1% by weight based on the cationic resin, which is considered to be sufficient.

Examples of neutralizing agents include acetic acid, hydroxyacetic acid, formic acid,
Suitable examples include low-molecular weight organic acids such as propionic acid.The proportion of the neutralizing agent is usually about 0.1 to 0.5 equivalents, preferably about ( ), 2 to 0.3 equivalents.

The proportion of water added in advance to the neutralized cationic resin or the mixture of this and the blocked polyisocyanate compound is based on the solid content of the resin (the total amount of the cationic resin and the blocked isocyanate compound) in the paint 100 It is 1 to 15 parts by weight, preferably 3 to 10 parts by weight.

The ratio of water is 1! If it is less than 15 parts by weight, the particle size will be large, the filter will be clogged, and the smoothness of the horizontal part of the coating film will be poor due to baking.On the other hand, if the proportion of water is more than 15 parts by weight, The viscosity of the neutralized product solution increases, and water and neutralized product separate during storage, making it unusable. Also,
Even if this material is forcibly dispersed in water, the particle size increases, which may clog the filter and cause baking, which is undesirable since the smoothness of the horizontal parts of the coating film will be poor.

The method of dispersing the water-containing neutralized product in water can be carried out using a conventional dispersing machine (for example, a disperser) without any particular restrictions.The solid content of the resin thus obtained is About 20-45% by weight, preferably about 30-45% by weight
40% by weight is desirable.

A curing catalyst, a fluid G1 preparation, a brown plant, an extender pigment, an anti-corrosive base material, etc. can also be added to the cationic electronic sign paint produced by the method of the present invention.

(Operation and Effects of the Invention) In the method for producing the cationic FM electrodeposition paint of the present invention, conventionally, the cationic groups in the organic solvent solution of the resin neutralizer for cationic electrodeposition paint are rounded by association of the cationic groups. When dispersed in water in such an aggregated form, the water becomes hydrated before the ionic associations are sufficiently dissociated, resulting in the formation of particles with large diameters. If a specific range of water is added in advance to an organic solvent solution,
When water is hydrated with ions, dissociation of ionic associations takes place, and in this way - when carried ion dissociation takes place, these are further hydrated in water and easily dispersed in water to form fine particles. be done.

(Example) Next, the present invention will be explained in detail with reference to Examples.

Example Epoxy resin-amine adduct 70 heavy parts (i 5 (solid content) per epoxy resin 6 Epikote 500 parts was dissolved in 7300 parts of methyl isobutyl ketone, and diethylamine was added and reacted. (resin with amine value 40) Diphenylmethane dicyanate 301/t alcohol-blocked acetic acid 1.3η night ionized water 5 // After mixing the above-mentioned formulation with a stirrer, mix this with deionized water being stirred. (Lid with resin solid content of 30 @ f1%: 227
(parts by weight) to obtain a water-absorbing liquid of the example.

Comparison f111 A sample was produced in the same manner as in the example except that deionized water was not used at all.

Comparative Example 2 A sample was produced in the same manner as in Example except for using 20 parts by weight of deionized water instead of 5 parts by weight of deionized water.

The results are summarized in the table.

Table 7 Average particle diameter': Measured with a spectrophotometer and calculated from the following formula:
The average particle diameter (μ) was determined using the calibration curve described in J. ol., 42 P145-152 (1964)).

Dispersion liquid fine: Average particle diameter was measured and visually observed. Residue: 1 ton of aqueous dispersion was passed through a 400-mesh wire mesh. The passed-through wire mesh was dried at 50°C for 1 hour, then weighed, and the pass-cut residue was calculated using the following formula.

Metal mesh type t after filtration (w9) - Weight of wire mesh before filtration (wI9
) L effect: A stainless steel plate was used as an anode in a bath using the water absorption liquid of Examples and Comparative Examples as an electrodeposition paint, and Llu (ratio of horizontal part to vertical part was 1/1, horizontal part was the counter electrode (anode)). Using a zinc hypophosphate iron plate bent to face the side as a cathode, electrolytic coating was applied to a film thickness of 20 sK. After washing the electrolytically coated test plate with water, it was baked at 170° for 30 minutes, and baking on the vertical portions was visually observed on the appearance of the coating.

Evaluation criteria ○: Excellent smoothness.

68 Partial puttu occurs.

×: Spots occur on the entire surface.

Claims (1)

[Claims] 1. In the method for producing a cationic electrodeposition paint, 1 to 15 parts by weight of water is added to the neutralized resin for the cationic electrodeposition paint based on 100 parts by weight of the resin solid content in the cationic electrodeposition paint. A method for producing a cationic electrodeposition paint, which comprises dispersing this material in water.