JPS62230868A - Coating composition for chipping resistance - Google Patents

Abstract

PURPOSE:The titled composition suitable for coating the surface of gasoline tank of automobiles, forming a coating film having characteristics to protect metallic products from chipping, obtained by blending a water-dispersible acrylic resin with a powdery filler and a fibrous filler in a specific ratio. CONSTITUTION:(A) 100pts.wt. calculated as solid content of a water-dispersible acrylic resin is blended with (B) 10-60pts.wt. powdery filler (e.g. talc, calcium carbonate, etc., preferably having 1-50mu particle diameter) and (C) 10-100pts.wt. fibrous filler (e.g. carbon fiber, etc., preferably having 10-200mum single yarn length, 0.1-3mum maximum diameter of section and 50-200 aspect ratio) together with other components to give the aimed composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a chipping-resistant coating composition that is coated on the surface of a metal product to protect the metal product from chipping. The chipping-resistant coating '11 composition of the present invention is used, for example, to coat the surface of an automobile gasoline tank.

[Prior Art I] A steel material plated with a lead-tin alloy is called a turn sheet and is highly extensible. Therefore, since sheet metal workability is not compromised, it has been widely used for automobile gasoline tanks and the like. This lead-tin alloy plating has extremely excellent anti-rust properties. However, if the plated surface is damaged due to scratches or the like, corrosion will progress from that area.

To prevent scratches on the plating surface,
Conventionally, the plated surface is coated with a chipping-resistant coating composition as a protective layer.

This conventional chipping-resistant coating composition is
As seen in Japanese Patent Application No. 187469, paints are generally used in which a water-dispersible acrylic resin is used as a binder and powdered fillers such as talc and calcium carbonate are mixed therein. And 300μ~8 by airless painting etc.
It is coated with a thick film of 00μ, dried and coated.

[Problems to be Solved by the Invention] In the conventional chipping-resistant coating composition described above,
There is a problem that good chipping resistance cannot be obtained unless the coating film thickness is increased to 300 μm to 800 μm. As a result, workability is poor and a large amount of coating composition is required.
They were worried about rising costs.

One possible method for improving the depping resistance is to reduce the amount of powder filler blended. That is, the amount of water-dispersible acrylic resin blended may be relatively increased to provide strength. However, conventional anti-chipping coating compositions have been applied to gasoline tanks and the like and then dried at high temperatures of 80°C to 120°C.

Therefore, when there is a large amount of resin component as mentioned above, film formation occurs early and the surface dries quickly, and the water vapor evaporated by the heat during drying presses the resin film, causing swelling in the coating film. There was a problem like this.

That is, when the amount of powdery filler is small, chipping resistance is improved, but swelling occurs. On the other hand, if there is a large amount of powder filler, water that becomes steam can be easily handled from the inside of the coating film to the outside and no swelling will occur, but if the film thickness is not thick, the chipping resistance will be poor. .

The present invention has been made in view of the above problems, and an object of the present invention is to provide a chipping-resistant coating composition that suppresses the occurrence of swelling during drying and has excellent depping resistance even in a thin film.

[Means for solving the problems] The chipping-resistant coating composition of the present invention contains 100 parts by weight of a water-dispersible acrylic resin as a solid content, and 10 to 6 parts by weight of a powdery filler.
0 parts by weight of the male filler and 10 to 60 parts by weight of the male filler, which is coated on the surface of a metal product to protect the metal product from chipping.

The water-dispersible acrylic resin used in the present invention is one obtained by polymerizing various vinyl monomers by emulsion polymerization, and examples of the seven monomers include styrene, alkylstyrene, alkyl acrylic acid or methacrylate, and acrylonitrile. , acrylamide, N-methylol acrylamide, methacrylonitrile, hydrocarbon esters having an alicyclic or aromatic ring of acrylic acid or methacrylic acid, etc., and their homopolymers or copolymer resins can be used. can.

Preferred monomer combinations include, for example, ethyl acrylate, isopropyl acrylate, and acrylic flJ-
n-propyl, isobutyl acrylate, n-acrylate
-Butyl, acrylic! ! Examples include homopolymers or copolymers of monomers such as -2-ethylhexyl.

The chipping-resistant coating composition of the present invention may optionally contain other water-dispersible resins, such as styrene-butadiene rubber latex, nitrile-butadiene rubber latex, butyl rubber latex, vinyl acetate emulsion, vinyl acetate copolymer emulsion, It is also possible to use a resin such as a polyurethane water compound mixed with the water-dispersible acrylic resin.

The powder filler referred to in the present invention can be the same as those conventionally used, such as talc, calcium carbonate, diatomaceous earth, mica, phosphoric acid, barium sulfate, graphite, alumina, iron oxide. , titanium oxide, silica, rubber powder, glass flakes, etc., may be used alone or in combination of two or more.

The shape of this powder filler is not particularly limited, but if the particle size becomes too large, clogging may occur during coating or unevenness may occur on the surface after coating. is preferred.

The above powder filler is water't>dispersible acrylic resin solid content 10
It is used at a ratio of 10 to 60 parts by weight to 0 parts by weight. If the formulation is less than 10 times, swelling will occur during drying,
When the weight exceeds 60 parts, the chipping resistance decreases.

The fibrous filler referred to in the present invention is not particularly limited as long as it has an m-fiber shape, and examples thereof include carbon fiber, rock wool, fibrous potassium titanate, fibrous magnesium sulfate, attapulgite, A-lastonite, and Ill-like filler. Barium sulfate asbestos or the like can be used.

The mN filler is mixed in an amount of 10 to 100 parts by weight based on 100 parts by weight of the solid content of the water-dispersible acrylic resin. If the amount of this fibrous filler is less than 10 parts, swelling may occur during drying.
If more than 10% is added, the chipping resistance will decrease and the appearance of the coating will also deteriorate.

The shape of the single fibers of this fibrous filler is not particularly limited, but the length is 10 to 200 μm and the maximum diameter of the cross section is 0.5 μm.
The thickness is preferably 1 to 3 μm.

If the cross-sectional diameter and quality are within this range, prevention of swelling during drying, chipping resistance, and surface appearance of the coating film can be maintained particularly well. In particular, it is preferable to use one having an aspect ratio of 50 to 200. Asbek! - If the ratio is within this range, the above performance can be maintained particularly high.

The total amount of the powder filler and the fibrous filler is desirably 50 to 160 parts by weight, or 16 parts by weight, based on 100 parts by weight of the solid content of the water-dispersible acrylic resin. If the total amount is less than 70 parts by weight, swelling tends to occur, and if it is more than 160 parts by weight, the chipping resistance will decrease when forming a thin film.

In addition to the above ingredients, the chipping-resistant coating composition of the present invention includes carbon black, color pigments such as organic pigments, rust preventive pigments such as metal chromates, metal phosphates, and metal metaborates, dispersants, Additives such as thickeners and organic solvents such as ethylene glycol and butyl cellosolve can also be mixed.

In order to coat the surface of the gold DM product with the chipping-resistant coating composition of the present invention, it is applied to the surface of the gold DM product using airless coating, air spray coating, or the like. After that, for example, 80℃~1
The film is cured by drying for 10 to 30 minutes at a temperature of 20°C. do. In addition, if the chipping-resistant coating composition of the present invention is used, there is no need to make a film as thick as 70 μm.
Even a thin film of ~200μ has sufficient chipping resistance.

Further, as in the conventional case, the film can be made thicker than 300 parts.

[Function] The chipping-resistant coating composition of the present invention contains a powdery filler and a 1111-type filler as fillers. Here, the fibrous filler is oriented in a nearly layered manner in the coating film, and together with the powder filler, it is in a nearly close-packed state. Therefore, even if the total amount of fillers blended is larger than the conventional one, the same chipping resistance as the conventional one can be obtained. In addition, the increase in the amount of filler prevents the occurrence of swelling. Therefore, even if the total amount of the coating composition is approximately the same as the conventional one, the film thickness can be made thinner while maintaining the same chipping resistance, and the swelling can be prevented to the same or greater extent. 3) It is possible to reduce the number of times of painting, and it is possible to reduce costs.Since the rough fibrous filler is oriented in a layered manner between the powder fillers, it is possible to reduce the impact force of pebbles etc. is dispersed, further improving chipping resistance.

[Example] The following is a concrete explanation using Examples. In addition, all parts mentioned below mean parts by weight.

180 parts (manufactured by Rubber Co., Ltd., solid content 55%), 5 parts of Boyz 530 (manufactured by Kao Corporation) as a dispersant, 10 parts of barium metaborate as a rust preventive agent, and 70 parts of water were added, and while stirring with a disper, I- ) 60 parts of tM calcium, 1 part of carbon black, and 10 parts of a fibrous magnesium compound (MOS, manufactured by Ube Industries, Ltd., diameter 1 μm, length 10 to 100 μm) as a fibrous filler were gradually added, and the mixture was thoroughly stirred. Thus, the chipping-resistant coating composition of Example 1 was obtained.

(2) Conditions for making coated plates Prepare a turn-seed plate made of lead-tin plated steel plate, apply the coating composition obtained above in an airless manner, let it set for 10 minutes at room temperature, and then apply so'cxio. +1
It was baked and dried under the conditions of 20° C. for 20 minutes. Two scales were prepared with film thicknesses of 100μ and 200μ. The extent to which swelling occurred during drying when the film was coated with a large thickness was also investigated, and with the coating composition of this example, almost no swelling occurred when the coating was coated with a thickness of 500 μm.

(3) Chipping resistance test" Two types of coated plates having film thicknesses of 100μ and 200μ obtained in Section 2 were subjected to a chipping resistance test to measure chipping resistance performance. The test method is as follows:
At an angle of 60 degrees to the coating surface of the coating plate (M-6
) was continuously dropped from a height of 2 m, and the aSω of the fallen nut when the substrate was exposed was evaluated. The results are shown in the table.

(Example 2) A chipping-resistant coating composition was prepared in the same manner as in Example 1 except that 100 parts of a fibrous magnesium compound was blended, and a coated plate was similarly prepared and a chipping resistance test was conducted. The results are shown in the table. In the case of this example, no swelling occurred during baking even when 17 films of 800 μm or more were coated.

(Example 3) A coating composition was prepared in the same manner as in Example 1 except that calcium carbonate was changed to 10 parts and the fibrous magnesium compound was changed to 100 parts, and a coated plate was similarly prepared and a chipping resistance test was conducted. . The results are shown in the table. In this example, as in Example 2, no swelling occurred even when a thick film of 800 μm or more was coated.

(Comparative Example 1) An irradiated crude product was prepared in the same manner as in Example 1 except that the m-male magnesium compound was not blended, and a coated plate was prepared in the same manner and a depping resistance test was conducted.

The results are shown in the table. In the case of Comparative Example 1, the film thickness was 1
When it exceeded 80μ, swelling occurred.

(Comparative Example 2) A coating composition was prepared in the same manner as in Example 1 except that 70 parts of calcium carbonate and no fibrous magnesium compound were added, and a coated plate was prepared in the same manner and a chipping resistance test was conducted. . The results are shown in the table.

In the case of the coating composition of Comparative Example 2, calcium carbonate was 1
The film thickness is 80 parts, but the film thickness is 80 parts more than Comparative Example 1.
Even at 0μ, almost no swelling occurred.

(Comparative Example 3) A coating composition was prepared in the same manner as in Example 1, except that 120 parts of calcium carbonate and no mm-shaped magnesium compound were blended, and a coated plate was similarly prepared and a chipping resistance test was conducted. The results are shown in the table. In addition, with the coating composition of Comparative Example 3, almost no swelling occurred even when the film thickness was 800 μm or more.

(Evaluation) Clearly from the table! The coating composition of the example containing the 1lIi-form magnesium compound does not cause sagging during drying even when the film thickness is increased, and is far superior to the comparative example. On the other hand, the chipping resistance is 1IIJf is 100μ, 20
Even though it is as thin as 0μ, it shows a value of 9 in the range of 2.5 to 3.5, and has performance equivalent to or higher than that of the comparative example. It is clear that this effect is due to the inclusion of a fibrous magnesium compound.

Claims (4)

[Claims] (1) 100 parts by weight of water-dispersible acrylic resin in solid content, 10 to 60 parts by weight of powdery filler, and 10 to 60 parts by weight of fibrous filler.
100 parts by weight, and is coated on the surface of a metal product to protect the metal product from chipping. (2) The chipping-resistant coating composition according to claim 1, wherein the single fibers of the fibrous filler have a length of 10 to 200 μm and a maximum cross-sectional diameter of 0.1 to 3 μm. (3) The single fiber of the fibrous filler has an aspect ratio of 50 to 2.
00. The chipping-resistant coating composition according to claim 1, which is 00. (4) The chipping-resistant coating composition according to claim 1, wherein the powder filler and the fibrous filler are blended in a total of 50 to 160 parts by weight based on 100 parts by weight of the solid content of the water-dispersible acrylic resin. thing.