JPS59138278A - Paint composition for electrodeposition matte coating - Google Patents

Abstract

PURPOSE:To provide the titled composition for the coating of an electrically conductive metal, etc., giving a uniform matte coating surface without introducing a matte-finishing process, and giving an easily controllable coating bath, by mixing an anionic electrodeposition paint with a specific epoxy-containing compound and a resin. CONSTITUTION:The objective composition is prepared e.g. by mixing (A) an anionic electrodeposition paint obtained by mixing (i) 100pts.wt. of a copolymer resin for electrodeposition coating with (ii) 100-3pts.wt. of an aminoplast resin (e.g. melamine-formaldehyde reaction product) with (B) a compound having >=2 epoxy groups per one molecule and having an epoxy equivalent of <=500 (reduced to non-volatile component) and a resin (e.g. ethylene glycol). The weight ratio of the non-volatile components of the component (A) to (B) is 3/1-60/1. USE:Coating of anodized or boehmite-processed aluminum, iron treated with zinc phosphate, iron phosphate, etc., and other metals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a matte electrodeposition coating composition for coating conductive objects. A composition for a matte electrodeposition paint that does not require the introduction of a matte process, can easily control the paint bath, and provides a uniform matte coating surface in a firing method (hereinafter referred to as the electrodeposition coating method). It is about things.

The purpose of coloring an object can be broadly divided into protecting the surface with water resistance, chemical resistance, etc., and improving the aesthetic appearance.

By coating a conductive substance using an electrodeposition coating method,
It is generally known that it imparts corrosion resistance and at the same time gives gloss to the surface, improving its commercial value. However, by reducing the gloss of the coating material, it actually improves its commercial value in a different sense. can do. In recent years, there has been an increasing demand for products coated with such matte coatings by electrodeposition coating.

Generally, when a matte coating is applied by electrodeposition coating, a powdery substance containing particles of an inorganic compound such as an inorganic pigment that is incompatible with the resin is mixed in the electrodeposition coating bath to roughen the surface of the coating and make it matte. A method of increasing the effect, and a method of roughening the coated surface using methods such as chemical treatment before and after baking the object coated with the electrodeposition using a conventional method have been proposed.

Although the latter method provides a relatively stable matte coating surface, it requires a matting process in addition to the normal electrodeposition coating process, making the process complicated; Additional personnel and chemicals will be required.

On the other hand, the 111J process is no different from ordinary electrodeposition coating, but in the case of matte inorganic pigments, they essentially have poor compatibility with the coating phase for E-coating, and have a large specific gravity. Since it has no solubility and dispersibility in water, which makes up the majority of the paint bath, it settles to the bottom of the electrocoating bath over time, so the paint film obtained by electrocoating cannot maintain a stable matte state. In other words, when a paint bath is stirred to prevent settling of matte pigments, the settled pigments roll up, causing, for example, the upper and lower surfaces of a workpiece placed horizontally in the bath.
There is a problem that there is a difference in the matte state. Therefore, controlling the dispersibility of the matte pigment in the bath becomes important and complicated.

Therefore, an object of the present invention is to provide a coating composition for matte electrodeposition coating that does not require the introduction of such a gloss coating process, can be easily controlled in an electrodeposition bath, and provides a uniform matte coating surface. It is.

That is, in the present invention, the anionic electrodeposition paint contains 2
This is a coating composition for matte electrodeposition coating, which is prepared by mixing a compound or resin having at least three epoxy groups and an epoxy equivalent (in terms of non-volatile content, hereinafter the same) of 500 or less. It should be noted that although the technique of adding a compound having an epoxy group to general compounded paints for the purpose of improving corrosion resistance has been known in the past, the present invention differs from this in that it aims at matting electrodeposition coatings.
Epoxy equivalents are also much smaller.

The anionic electrodeposition paint (hereinafter referred to as (I)) in the present invention is essentially water-soluble or water-dispersible;
It is necessary that it has the property of becoming insoluble on the surface of the conductive coating that becomes the electrode during anionic electrodeposition coating and precipitating to form a coating film. That is, any paint used in conventional anionic electrodeposition coating may be used.

An example is the copolymerization of a monomer having an ethylenically unsaturated bond that can be copolymerized with a small amount of one or more types of polymerizable unsaturated organic carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid. Add aminoplast resin to the product, add pigment paste if necessary, and then add one or more hydroxides of amine, alkali metal, alkali gold, etc. This is coating 1, which is partially or completely neutralized and whose water solubility increases by the same amount as its water dispersibility. The anionic electrodeposition paint (1) needs to be thoroughly mixed with an epoxy compound or resin (hereinafter referred to as (11)), so it must be mixed with an epoxy compound or resin (hereinafter referred to as (11)). It is important that the viscosity is 1 void or more when measured at °C.

In addition, the aminoplast resin used at this time may be urea-formaldehyde, melamine or pensoquanamine-formaltehyde reaction product, or a partial or complete alcohol modification product of these, especially melamine-formaltehyde reaction product. Preferably, a partially distilled or completely notyl ether compound or a butyl ether compound is used.

The preferred mixing ratio is 100 parts by weight of the aminoplast resin to 100 parts by weight of the non-volatile content of the above-mentioned copolymer resin for electrodeposition coatings.

In the present invention, the compound or resin (n) having two or more epoxy groups per molecule and having an evoquino equivalent of 500 or less refers to polyhydric alcohol glyc/dyl ethers, such as ethylene glycol, zoglyciple ether, Examples include glycerol polyglycyl ether, glycerol polyglycyl ether, sorbitol polyglycidyl ether, and acrylic resins made by copolymerizing glycerol polyglycrylate or methacrylate with other copolymerizable monomers. Any substance having two or more epoxy groups and an epoxy equivalent of 500 or less can be used. Epoxy equivalents of 500 or more are not preferred because a homogeneous mixture with the anionic electrodeposition paint (I) cannot be obtained and it takes a long time at high temperature to prepare a microkeloid of the mixture.

The composition according to the present invention comprises an electrodeposition coating material (I) and an epoxy compound or resin (II) in a combination of (I)/(II).
-3/1 to 60/1 (nonvolatile weight ratio, same below)
It is obtained by mixing in the ratio of , diluting with pure water so that the non-volatile content becomes ~50%, and leaving it at room temperature for one month. (Hereinafter, this composition will be referred to as side)/ζ After diluting with pure water, it is better to heat it at 40 to 85°C for 24 to 1 hour to shorten the time. (IJ ト(II
) When the mixing ratio force (I) / (If) -3/ 1 or more, the composition GID is not a uniform dispersion liquid size or a solution, but the liquid containing sediment is still The entire product becomes a gel, making it unsuitable for use as a paint. When (i)/(II) = 60/1 or more, a matte coating film cannot be obtained when used for matte electrodeposition purposes. Diluting the mixture of (I) and (II) with pure water g4.
This can be done by the usual method of adding pure water little by little using a normal stirring device, and then adding the remaining pure water all at once when the viscosity of the mixture has decreased or when the mixture has been dispersed in water. Diluting with pure water to reduce the non-volatile content to less than 10% is uneconomical due to increased transportation costs; on the other hand, if it is more than 50%, the entire system will be damaged during the heating process in the next step, which is necessary to shorten the reaction time. It does not look good if it is in a gel state.

The composition obtained as described above is a homogeneous liquid containing no sediment, and when dried on a glass plate at 50° C. for 30 minutes, 4 volumes of acetone remain. Therefore, the composition (III) is a homogeneous material containing microgel, and the anionic electrodeposition paint (1) is applied around the microgel.
It is presumed that the particles act similarly to surfactants and envelop them, making it possible to provide a water-retaining bath paint containing sedimentary substances. It is assumed that when the electrodeposited coating is heated above 100'C, the contained microgel material can prevent flow and provide a matte coating.

The composition side can be used alone, but it can also be used in combination with (r) to obtain the desired gloss value. When the composition side and the electrodeposition paint (1) are mixed and used, the mixing ratio is Tsukuda)/(I) -1/9 to 110 (non-volatile content weight ratio, the same applies hereinafter), preferably 1 Mix at a ratio of /4 to 9/1. When GID/(1)=1/9 or less, it is not possible to produce a matting effect on the electrodeposition coating. The method of mixing the book and (1) is to mix them so that the above blending range is achieved, regardless of the non-volatile content, and add each sweet to the electrodeposition coating bath and dissolve it to achieve the above blending ratio. You can do it like this.

The mixture of (1) and the matte electrodeposition coating composition obtained as described above has a non-volatile content of 5 to 15% after adding an amine if necessary. Prepare the electrodeposition bath solution by diluting it with pure water.

Generally speaking, materials to be coated can be used without problems as long as they are electrically conductive, such as aluminum, aluminum treated with alumite or boehmite using known methods, iron treated with zinc phosphate or iron phosphate, and other metals. etc. can be used. There is no problem with the electrodeposition coating conditions that are normally used, and the baking and drying conditions can be carried out under the usual conditions.

Next, the effects of the present invention will be explained by examples, but the present invention is of course not limited to these.

Example 1 In a flask equipped with a condenser, a thermometer, and a stirrer, 30 parts of Impropatool, 10 parts of butyl cellosolve, 6 parts of acrylic acid, 40 parts of ethyl acrylate, ? - Charge 15 parts of hydroxyethyl methacrylate, 39 parts of methyl tutaacrylate, 15 parts of totinormercaptan, and 1 part of azobisinbutyronitrile, filter at 80°C for a while, then add 2 parts of azobisinbutyronitrile after 1 hour. The polymerization was then completed for another 3 hours, and the internal temperature was lowered to 60°C. Then, 76 parts of dinotylaminoethanol and 24.0 parts of pure water were added, and after stirring for 30 minutes, the internal temperature was lowered to 65°C. After the temperature was lowered, 446 parts of Nikalunk MX-40 (manufactured by Sanwa Chemical Co., Ltd.) was added and stirred for 20 minutes to prepare a No. 2 electrodeposition paint (I) with a non-volatile content of 71.0%. (I) 169 in a stainless steel beaker
．． Add 5 or 6 parts of "Tenacol" EX-612 (manufactured by Nagashio Sangyo ■, epoxy equivalent weight 170 nrbitol polygsocidyl ether) for 20 minutes using a stirrer equipped with a two-blade paddle type stirring bowl. , p, +η) mixed with pure water 55
．． 8 parts of 500 (p-lη) were added under stirring for 15 hours, then 856 parts of pure water were added and stirring was continued for 20 minutes.The contents were then placed in a flask equipped with a stirrer and stirred for 15 hours. Heat at 70°C for 8 hours to obtain a composition container (40% non-volatile content).Pour 250 parts of the composition container into a stainless steel beaker and add 750 parts of pure water so that the non-volatile content is 10%.
After adding 14 parts of ethylamine and stirring for 10 minutes, 14 parts of ethylamine was added and the mixture was stirred for 1 day under red sea bream tinksutara, then electrocoated on an alumite-treated aluminum plate and dried at 180°C for 14 minutes to give a gloss of 14. (film thickness 9μ
) A homogeneous coating film was obtained.

Sunda BT #144 treated steel gloss 6% (film thickness 25
A homogeneous coating film of μ) was obtained.

Example 2 70.4 parts of the electrodeposition coating (1) of Example 1 and 1 part of the composition container
Pour 25 parts into a stainless steel beaker, add 1.4 parts of triethylamine, stir for 10 minutes, and reduce the non-volatile content to 10%.
A uniform electrodeposition bath paint was prepared by gradually adding 805.2 parts of pure water so that was gotten.

Is it light when using Shoda BT#144 treated steel plate? R6% (film thickness 2
A homogeneous coating film of 7μ) was obtained.

Example 3 After adjusting the mark using epoxy compound resin (n) in place of ``Tenacol'' EX-612 in Example 1,
Evaluation was made by the method of Example 2. The results are shown in Table-1. Furthermore, ``Tenacol'' EX-320 and ``Bunacol''
``EX-622 is both manufactured by Nagashio Sangyo ■, and AX-86
This is a prototype resin bundled. AX-86 contains 38 parts of inpropanol, 40 parts of glyphnor methacrylate, 60 parts of butyl acrylate, 6 parts of totiflumercaptan, and 1 part of azobisin butyronitrile in a flask equipped with a condenser, thermometer, and stirrer. Prepare the mixture, stir at 80°C for a period of time, then add 02 parts of azobisisobutyronitrile every hour, and stir for an additional 2 hours.

Claims (1)

[Claims] A paint composition for matte electrodeposition coating, which is prepared by mixing an anionic electrodeposition paint with a compound or resin having two or more epoxy groups per molecule and having an epoxy equivalent of 7 (non-volatile fraction n) of 500 or less.