JPS63270777A - Electrodeposition coating composition - Google Patents

Abstract

PURPOSE:To obtain an electrodeposition coating compsn. capable of forming a coating film excellent in applicability to the edge of an article to be coated without adversely affecting the surface smoothness of a general face, by adding an acicular substance and a rust preventive pigment to a coating compsn. CONSTITUTION:An electrodeposition coating compsn. is obtd. by adding to a coating mixture comprising a base resin, a pigment, a solvent, various additives, etc. an acicular substance and a rust-preventive pigment in respective amts. of 1-40 and 0.1-5pts.wt. per 100pts.wt. whole nonvolatile components of the mixture. The acicular substance may be either org. or inorg. Examples of the inorg. substances include ceramic whisker, metal whisker, and metal fibers. Examples of the org. substances include org. fibers, such as acrylic fibers and fluorofibers. With respect to the morphology of the acicular substance, it is pref. that the diameter be 0.01-1.0mu, the length be 0.1-10mu, and the ratio of the length to the diameter be at least 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrodeposition coating composition used for rust prevention of automobile bodies and the like.

[Conventional technology]

Electrodeposition paints have excellent corrosion resistance and can be applied to the inner surfaces of structures, so they are widely applied to automobile bodies and the like that have many single-bag structures. however,
Electrodeposition paints currently in use are designed to have a three-pigment volume concentration (PVC) of 25% or less because they place more emphasis on ensuring the smoothness of the film surface than on the appearance of car bodies and the like.

For this reason, when the coating film is baked after electrodeposition coating.

There is a problem in that the paint on the edges of cut parts of the material, punched holes, etc. flows, and the edges are easily exposed, resulting in poor corrosion resistance at the edges.

On the other hand, when using electrodeposition paint with PVC 30% or more, 8
Although the corrosion resistance of the abutment part is improved, the pigment tends to settle, and the surface smoothness of the female surface is poor.

Cannot be used due to high appearance.

Currently, the rust prevention of this edge part is done after applying electrodeposition paint.
This problem is dealt with by applying an organic sealer made of vinyl chloride with a plasticizer added. but.

The edge portion is structurally difficult to coat and requires a large number of man-hours.

As described above, conventional electrodeposition paints have problems in that the coating on the edges is not always sufficient and the rust prevention properties are poor.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems of the prior art. An object of the present invention is to provide an electrodeposition coating composition that can form a coating film with excellent paintability.

[Means for solving problems]

The electrodeposition coating composition of the present invention contains a basic resin and a pigment.

In coating compositions consisting of solvents and various additives,
The coating composition contains 1 to 40 parts by weight of acicular substances and 0.1 to 0.1 to 40 parts by weight of a rust preventive pigment based on 100 parts by weight of total nonvolatile components.
It is characterized by containing 5 parts by weight.

The needle-like substance that is the most distinctive feature of the present invention is:

It may be an inorganic substance or an organic substance, and is not particularly limited. For example, alumina is an inorganic substance.

Ceramic whiskers such as beryllia, boron carbide, silicon carbide, and graphite; metal whiskers such as S-5 iron and ninkel; and glass fibers.

Ceramic fiber, carbon fiber, rock wool, potassium titanate fiber, alumina fiber, zirconia fiber,
Inorganic fibers such as metal fibers are used. Further, as the organic substance, organic fibers such as acrylic fibers, acetate 1AIi fibers, nylon, vinylon, polyester fibers, and fluorine fibers are used.

The shape of this needle-like substance is 0.01 μm to 1 μm in thickness.
．． It is desirable to use a material with a length of 0 μm, a length of 0.1 pm to 1 Opm, and a ratio of length to thickness of 10 or more. If the thickness exceeds 1.0 μm or the length exceeds 0 μm, the smoothness of the coating film will not be obtained and the quality of the appearance will be significantly reduced. Moreover, when the ratio of length to thickness is less than 10,
The effect on the flowability of the coating film at the edge portion of the needle-like substance is reduced.

The acicular substance is present in the paint composition in an amount of 1 to 40 parts by weight per 100 parts by weight of total nonvolatile matter.

If this amount is less than 1 part by weight, the effect on the flowability of the coating film at the edge portions will not be sufficient.

If it exceeds 40 parts by weight, the pvc (pigment volume concentration) will increase and the physical properties of the coating will deteriorate. In addition.

Particularly preferred is 3 to 20 parts by weight.

Another feature of the present invention is that, in addition to the above-mentioned acicular substance, it contains 1 to 5 parts by weight of a rust preventive pigment. This anti-rust pigment includes lead powder, lead oxide, red lead, cyanamide lead,
Lead-based pigments such as calcium leadate, chromate-based pigments such as zinc chromate, strontium chromate, and basic lead chromate.

Alternatively, conventionally used antirust pigments such as zinc pigments can be used as they are. This anti-rust pigment is added in a range of 0.1 to 100 parts by weight per 100 parts by weight of the total non-volatile components in the coating composition.
5 parts by weight are placed. If it is less than 0.1 parts by weight, sufficient rust prevention performance cannot be obtained, and if it exceeds 5 parts by weight, no improvement in rust prevention performance is observed even if it is blended. Furthermore, these anti-rust pigments are known to be harmful to the human body, and it is desirable to reduce their blending amount as much as possible. A particularly desirable range is 1 to 3 parts by weight.

The mixing amount of the acicular substance and anti-corrosion pigment is 50% or less for PVC in order not to deteriorate the physical properties of the coating film.

In particular, in order to obtain sufficient smoothness of the coating film surface, it is desirable that the PVC content be 25% or less.

The basic resin used in the electrodeposition coating composition of the present invention can be either a resin for anionic electrodeposition coatings or a resin for cationic electrodeposition coatings. Resins for anionic electrodeposition coatings include those that have acidic polar groups such as carboxyl groups in their skeletons and are made water-soluble by neutralizing them with inorganic or organic bases.

For example, maleated oils, polybutadiene resins, epoxy esters, acrylic resins, phenolic resins.

Examples include polyester resin (alkyd resin) and mixtures thereof. In addition, as resins for cationic electrodeposition coatings, there are resins that have basic polar groups such as amino groups in their skeletons and are made water-soluble by partially neutralizing them with inorganic or organic acids. Epoxy resin, epoxy urethane resin,
Examples include polyamide, acrylic resin, polybutadiene resin, and mixtures thereof.

Furthermore, the electrodeposition coating composition of the present invention may optionally contain 1
Various additives such as commonly used color pigments, extender pigments, suspending agents, dispersants, antifoaming agents, plasticizers, dryers, etc. can be added and mixed.

Examples of metal materials that can be coated with the electrodeposition coating composition of the present invention include metals 9 that are generally coated by electrodeposition.

Iron, steel, galvanized steel, etc. may be used, and chemically treated steel may also be used.

In order to apply the electrodeposition coating composition of the present invention, conventional coating methods can be applied as is, and a coating film thickness of 10 to 30 μm exhibits sufficient antirust performance. Also.

The method for drying the coated film after painting can also be carried out in the same manner as in the past.

[Operation and effects of the invention]

The electrodeposition coating composition according to the present invention forms a coating film with excellent coating properties such as corrosion resistance on the edge portions of objects to be coated.

Furthermore, the surface smoothness of the general surface other than the edge portions is not affected. That is, compared to the properties of the coating film produced by conventional electrodeposition coating compositions, it is completely comparable in terms of the quality of the coating film appearance after baking and the corrosion resistance on a flat plate.

Excellent paintability on edges.

This is because the pigments contained in conventional electrodeposition paint compositions are spherical and the paint film tends to flow from the edges during baking, whereas the pigments contained in the paint composition of the present invention have an acicular shape. This is because the substance prevents the coating film from flowing.

Furthermore, the thickness of the needle-like substance is 0.01 to 1 μm.

Length 0.1 to 10 μm and length to thickness ratio of 1
If 0 or more is used, the amount can be increased without further deteriorating the appearance of the coating film, and the rust prevention performance will be even more excellent.

Furthermore, in the electrodeposition coating composition of the third invention, the antirust performance is improved due to the synergistic effect of the acicular substance and the antirust pigment. Therefore, compared to conventional rust-preventing paint compositions, the amount of rust-preventive pigment can be reduced, which is superior in terms of pollution.

〔Example〕

Hereinafter, this will be explained in detail using examples. In addition.

All percentages shown below are percentages by weight.

(1) Paint manufactured by 11 [Example 1] Resin for anionic electrodeposition paint (Watersol 5141
A mixture of LP and Watersol 5193LPA in a ratio of 2:l, manufactured by Dainippon Ink Chemical Industries, Ltd., non-volatile content 78%), 73%, silicon carbide whiskers as needle-shaped substances (5CW manufactured by Tateho Chemical Industries, Ltd.) 3%, strontium chromate 1%, carbon black 1%, kaolin 1%.

A mixture of 0.1% dispersant, 0.1% antifoaming agent, 11% isopropyl alcohol, 2% triethylamine, 4% acetone, and 3.8% ion-exchanged water was dispersed in a sand mill to obtain the same composition as in Example 1. An anionic electrodeposition coating composition was prepared.

[Comparative Example 1] Comparative Example 1 was carried out in the same manner as in Example 1, except that silicon carbide whiskers and strontium chromate were not blended, and 9 carbon black and kaolin were blended at 3% each.
An anionic electrodeposition coating composition was prepared.

[Comparative Example 2] An anionic electrodeposition coating composition of Comparative Example 2 was prepared in the same manner as in Example 1 except that strontium chromate was not blended and 1.5% each of carbon black and kaolin were blended.

[Comparative Example 3] Example 1 except that silicon carbide whiskers were not blended and 2.5% each of carbon black and kaolin were blended.
An anionic electrodeposition coating composition of Comparative Example 3 was prepared in the same manner as in Comparative Example 3.

[Example 2] Resin for cationic electrodeposition paint (EC-1800-15010
, manufactured by Nippon Petrochemical Co., Ltd., 72% non-volatile content (90%), 4% carbon fiber, 1% lead silicate, 1% carbon black, 1% titanium dioxide, 0.1% dispersant, 0.1 antifoaming agent. %, dryer 0.3%, ethyl cellolub 14%, acetic acid 2%, and ion exchange water 4.5% were blended and dispersed in a sand mill to prepare the cationic electrodeposition coating composition of Example 2.

[Comparative Example 4] A cationic electrodeposition coating composition of Comparative Example 4 was prepared in the same manner as in Example 2, except that carbon fiber and lead silicate were not blended, and 3.5% each of carbon black and titanium dioxide were blended. was prepared.

[Comparative Example 5] Example 2 except that lead silicate was not blended and carbon black and titanium dioxide were blended at 1.5% each.
A cationic electrodeposition coating composition of Comparative Example 5 was prepared in the same manner as above.

[Comparative Example 6] A cationic electrodeposition coating composition of Comparative Example 6 was prepared in the same manner as in Example 2, except that carbon fiber was not blended and carbon black and titanium dioxide were blended at 3% each.

(2) Test A commercially available cold-rolled steel plate measuring 70 x 150 x 0.8 mm was used.

As shown in Figure 1, sandpaper (1
No. 000) 2 is attached, and this is fixed to the support stand 3. The test steel plate 4 is attached to the holder 5 having an inclination angle (θ) of 30° and 60°, and the edge portions are set at 30″ and 60＠.
Polished corners. Next.

A conventional immersion zinc phosphate treatment was performed.

Each of the coating compositions obtained above was mixed with a non-volatile component of 10
It was diluted with ion-exchanged water to a concentration of ~15%, and electrodeposited on the steel plate to a dry film thickness of 20 μm.
After washing with water, Example 1 and Comparative Examples 1 to 3 were heated at 170°C x 3
0 minutes, Example 2 and Comparative Examples 4 to 6 at 200°C x 30
The test was carried out after baking and drying under the conditions of 10 minutes.

In the test, a salt water spray test was conducted in which 5% salt water was sprayed at 35°C onto a test piece in which cross-cuts were made on the coating film using a knife. The results are shown in Tables 1 and 2. In the table, the number of black rusts is the number of black rusts generated per 10 cm of edge length, and the blister width is the maximum width of one side of the blisters from the cross-cut portion.

As is clear from Tables 1 and 2, Examples 1 and 2 are coating compositions of the present invention.

No abnormality of the coating film occurred at the edges in the salt spray test. Furthermore, in Examples 1 and 2, the width of the bulge at the flat cut portion was smaller than that in the comparative example, and it was found that it did not affect the surface smoothness of the general surface other than the edge portions.

In addition, in the coating composition of Example 1, strontium chromate was fixed at 1% and the amount of silicon carbide (SiC) whiskers was varied, and
Test pieces were prepared in the same manner as in Example 1, with the amount of whiskers fixed at 3% by weight and the amount of strontium chromate varied. Regarding the SiC whiskers in which the blended amount was changed, the salt water spray time required to cause spot rust on the edge part was determined in the same salt water spray test as in Example 1 (polishing inclination angle (θ) = 30°). and paint gloss immediately after dry baking (60
°Gross) was measured. Also.

Regarding the products with varying amounts of strontium chromate, in the same salt spray test as in Example 1 (oblique angle (θ) = 30° around polishing 1), the blistering width at the flat cut portion reached 3 mm. The salt water spray time was measured. The results are shown in Figures 2 and 3 (in Figure 2, curve 2 represents the salt water spray time).

The curves 1 and 1 indicate the gloss of the paint, and the curve 1 represents the practical limit of the gloss of the paint film. ).

It is clear from the figure that a coating film with excellent paintability at the edges can be obtained without affecting the surface smoothness of the general surface if the blending amount of the acicular substance and anti-corrosion pigment is within a certain range. .

[Brief explanation of drawings]

Figure 1 is a diagram showing the apparatus for polishing the paint film in Example 1, and Figures 2 and 3 are graphs showing the influence of the blending amounts of the acicular substance and antirust pigment on the coating performance. be.

Claims (4)

[Claims] (1) In a coating composition consisting of a basic resin, a pigment, a solvent, various additives, etc., the coating composition contains 1 to 40 parts by weight of acicular substances and an inhibitor based on 100 parts by weight of total nonvolatile components. Rust pigment is 0.1~
5 parts by weight of an electrodeposition coating composition. (2) The needle-like substance has a thickness of 0.01 to 1 μm and a length of 0.1
The electrodeposition coating composition according to claim 1, wherein the electrodeposition coating composition has a length to thickness ratio of 10 or more and a length to thickness of 10 μm or more. (3) The needle-like substance is an inorganic whisker or fiber;
Alternatively, the electrodeposition coating composition according to claim (1), comprising one or more types of fibers of organic substances. (4) The electrodeposition coating composition according to claim (1), wherein the anticorrosive pigment is one or more of chromate-based, lead-based, and zinc-based pigments.