KR20250049588A - Coating composition of pre-coated metal sheet for fabricating fuel pump cover of automotive vehicles - Google Patents

Abstract

The present invention relates to a paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, and comprises a polyester resin, a solvent, a crosslinking agent, a pigment, a curing catalyst, an interlayer adhesive, a leveling agent, and an antifoaming agent. In the paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, the polyester resin comprises an A resin for reinforcing flexibility and enhancing processability, and a B resin for improving adhesion, and the A resin has a molecular weight of 20,000 to 30,000, an hydroxyl value of 20 to 40 mgKOH/g, an acid value of 1 to 5 mgKOH/g, and a glass transition temperature of 5 to 15°C, and is contained in an amount of 30 to 40 wt% based on the total paint composition, and the B resin has an aromatic component of 40 to 60 wt%, a weight average molecular weight of 20,000 to 30,000, and an hydroxyl value of 10. It is characterized by having an acid value of 1 to 3 mgKOH/g, a glass transition temperature of 50 to 70°C, and being contained in an amount of 20 to 40 wt% with respect to the entire paint composition.

Description

{COATING COMPOSITION OF PRE-COATED METAL SHEET FOR FABRICATING FUEL PUMP COVER OF AUTOMOTIVE VEHICLES}

The present invention relates to a paint composition for a pre-coated metal (PCM) steel sheet for manufacturing an automobile fuel pump cover, and more specifically, to a paint composition for a PCM steel sheet for forming the cover by first painting a PCM paint on the steel sheet and then forming the cover, instead of performing electrodeposition painting after manufacturing the cover for an automobile fuel pump.

There are two types of steel plate coating methods: the post-coating method, in which the steel plate is painted after being shaped and processed, and the pre-coating method, in which the steel plate is painted before being shaped and processed.

The above post-coating method has low equipment costs and is advantageous for small-scale production, but has the disadvantage of making it difficult to produce uniform products and mass-produce them.

In comparison, the pre-coating method has the advantages of being able to produce uniform products, having less paint loss, and being able to mass-produce in a short period of time.

Steel sheets coated with the above-mentioned pre-coating method are commonly called PCM (Pre-Coated Metal) steel sheets, and the paint used for pre-coating is called PCM paint.

Meanwhile, when manufacturing a fuel pump cover for an automobile, the cover is usually molded and then electroplated.

The above-mentioned electrodeposition coating method places an automobile fuel pump cover, which is made by pressing a steel plate, into a tank containing a water-soluble resin paint, and passes an electric current to form a coating film on the surface of the processed cover.

However, the above-mentioned electroplating method has the problem that it increases the generation of waste because a large amount of paint must be injected into the tank, and the generation of a large amount of waste pollutes the environment.

In addition, the above-mentioned electroplating method has the disadvantage of increasing the work man-hours and reducing productivity.

Meanwhile, corporate ESG (Environment, Social, Governance) management has been emphasized recently, and there is a particular demand for minimizing environmental impact.

Accordingly, there is a demand for the development of a painting method that can replace the electrodeposition painting method that generates a large amount of waste when manufacturing automobile fuel pump covers.

The present invention is proposed to solve the problems of the above-mentioned prior art, and the purpose of the present invention is to provide a PCM paint composition that enables, when manufacturing an automobile fuel pump cover, to first apply paint to the steel plate and then form the fuel pump cover without performing electrodeposition painting after forming the steel plate.

Another purpose of the present invention is to minimize environmental pollution by minimizing the generation of waste during painting work.

Another object of the present invention is to reduce man-hours when manufacturing an automobile fuel pump cover, thereby lowering manufacturing costs and improving productivity.

Another object of the present invention is to increase the flexibility of a steel plate to improve processability and at the same time improve the adhesion of paint.

In order to achieve the above object, a paint composition according to the present invention comprises a polyester resin, a solvent, a crosslinking agent, a pigment, a curing catalyst, an interlayer adhesive, a leveling agent, and an antifoaming agent, wherein, in the paint composition of a PCM steel sheet for manufacturing an automobile fuel pump cover, the polyester resin comprises an A resin for reinforcing flexibility and enhancing processability, and a B resin for improving adhesion, and the A resin has a molecular weight of 20,000 to 30,000, an hydroxyl value of 20 to 40 mgKOH/g, an acid value of 1 to 5 mgKOH/g, and a glass transition temperature of 5 to 15°C, and is contained in an amount of 30 to 40 wt% based on the total paint composition, and the B resin has an aromatic component of 40 to 60 wt%, a weight average molecular weight of 20,000 to 30,000, an hydroxyl value of 10 to 30 mgKOH/g, It is characterized by having an acid value of 1 to 3 mgKOH/g, a glass transition temperature of 50 to 70°C, and being contained in an amount of 20 to 40 wt% with respect to the entire paint composition.

In addition, it is characterized in that the molecular structure of the A resin contains 25 to 30 wt% of one monomer among propanediol, 1,6 hexanediol, and 1,4 butanediol.

In addition, the solvent is characterized in that it is contained in an amount of 10 to 20 wt% with respect to the entire paint composition.

In addition, the crosslinking agent is characterized in that it contains 5 to 10 wt% of a methyl etherified melamine resin having a methoxy group with respect to the entire paint composition.

In addition, the pigment is characterized in that it is a titanium oxide centered on carbon black and is contained in an amount of 2 to 5 wt% with respect to the entire paint composition.

In addition, the curing catalyst is characterized in that it is a neutralized product obtained by neutralizing any one sulfonic acid selected from p-toluene sulfonic acid (p-TSA), dinonylnaphthalene sulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA), and fluoro sulfonic acid with a secondary amine or epoxy, and is contained in an amount of 1 to 2 wt% with respect to the entire paint composition.

In addition, the interlayer adhesive is characterized in that it is contained in an amount of 0.5 to 2 wt% based on the total paint composition, and is a polysiloxane copolymer or a low molecular unsaturated polycarboxylic acid polymer.

In addition, the leveling agent and the antifoaming agent are each contained in an amount of 0.5 to 1 wt% with respect to the entire paint composition.

And the PCM steel sheet for manufacturing an automobile fuel pump cover according to the present invention is characterized by comprising a base steel sheet, a pretreatment layer formed on both sides of the base steel sheet, an undercoat layer formed on the pretreatment layers on both sides, and a topcoat layer formed on both sides of the basecoat layer.

According to the present invention, since electrodeposition painting is not performed as in the past when manufacturing an automobile fuel pump cover, there is an effect of minimizing the generation of waste.

In addition, it can minimize the generation of waste during painting work, thereby reducing environmental pollution and helping companies comply with ESG management.

In addition, compared to the existing electroplating method, it can reduce equipment costs and reduce labor costs, thereby lowering manufacturing costs.

Additionally, it has the effect of improving productivity by reducing labor costs.

In addition, the paint composition according to the present invention uses a mixture of Resin A, which maximizes the flexibility of the resin backbone, and Resin B, which maximizes the molecular weight.

This has the effect of improving processability while also improving the adhesion of paint.

In addition, by applying amorphous copolyester resin, there is an effect of improving the interlayer adhesion of the coating layer.

Figure 1 is a cross-sectional view of a PCM steel plate for manufacturing an automobile fuel pump cover according to the present invention.

Hereinafter, preferred embodiments of a PCM steel plate paint composition for an automobile fuel pump cover according to the present invention will be described in detail.

The polyester resin of the paint according to the present invention is composed of polyester A resin and polyester B resin (hereinafter simply referred to as ‘A resin’ and ‘B resin’).

It is preferable that the above resin A is contained in an amount of 30 to 40 wt% of the total composition, and the resin B is contained in an amount of 20 to 40 wt% of the total composition.

In addition to the above resin component, the composition contains 10 to 20 wt% of a solvent, 5 to 10 wt% of a crosslinking agent, 2 to 5 wt% of a pigment, 1 to 2 wt% of a curing catalyst, 0.5 to 2 wt% of an interlayer adhesive, 0.5 to 1 wt% of a leveling agent, and 0.5 to 1 wt% of an antifoaming agent.

In addition, it is preferable that the coating method of the PCM paint according to the present invention be a 2-coat method of base coat and top coat.

Below, the paint composition according to the present invention is described for each component.

<Polyester resin>

The polyester resin according to the present invention is composed of resin A, which is a flexibility-enhancing resin, and resin B, which is an adhesion-enhancing resin.

The above A resin has enhanced flexibility to improve processability, and preferably has a molecular weight of 20,000 to 30,000, an acid value of 20 to 40 mgKOH/g, an acid value of 1 to 5 mgKOH/g, and a glass transition temperature of 5 to 15°C.

And the above A resin is contained in an amount of 30 to 40 wt% with respect to the entire composition.

If the content of the above A resin exceeds 40 wt%, workability deteriorates, and if it is less than 30 wt%, it becomes difficult to maintain the workability and durability of the coating film.

In addition, in order to maintain the processability of the coating, the molecular structure of the A resin contains 25 to 30 wt% of one monomer among propanediol, 1,6 hexanediol, and 1,4 butanediol.

If the content of the above monomer exceeds 30 wt%, workability deteriorates, and if it is less than 25 wt%, it becomes difficult to maintain the processability and durability of the coating film.

In addition, the B resin contains an aromatic component in an amount of 40 to 60 wt% relative to the B resin to increase adhesion.

If the content of the above aromatic monomer exceeds 60 wt%, workability deteriorates, and if it is less than 40 wt%, it becomes difficult to maintain the adhesion of the coating film.

And the B resin has a weight average molecular weight of 20,000 to 30,000, an acid value of 10 to 30 mgKOH/g, an acid value of 1 to 3 mgKOH/g, a glass transition temperature of 50 to 70°C, and is contained in an amount of 20 to 40 wt% with respect to the entire composition.

If the content of the above B resin exceeds 40 wt%, there is a problem that the resin content in the paint increases excessively and the drying rate of the paint film decreases.

In addition, if the content of the above B resin is less than 20 wt%, there is a problem of reduced processability and adhesion of the coating film.

[Table 1] below shows the properties of examples and comparative examples of resin A according to the present invention, [Table 2] shows examples and comparative examples of resin B according to the present invention, and [Table 3] compares the properties of resin A and resin B according to the present invention and conventional top-coat resins.

Examples and comparative examples of A resin according to the present invention division Example 1 Example 2 Example 3 Example 4 Comparative example
alcohol EG 5.0 5.0 3.0 3.0 - NPG 14.0 12.0 12.0 9.0 34.0 1.6HD 26.0 - - 30 6/0 PD - 28.0 30.0 - -
mountain IPA 32.0 37.0 25.0 35.0 35.0 TPA 15.0 18.0 20.0 23.0 5.0 AA 8.0 - 10.0 - Additive (DBTO) 0.1 0.1 0.1 0.1 0.1 specific gravity 1.05 1.05 1.05 1.05 1.05 viscosity W X W X X Solid content 35.3 36.7 37.1 38.0 51.5 Mountain 2.5 2.1 2.1 5.0 5.0 Molecular weight 21,000 21,500 23,000 24,000 10,000 Hydroxyl value 29 28 27 26 40 NPG: neopentyl glycol, EG: ethylene glycol, 1,6HD: 1,6 hexanediol, PD: propanediol
IPA: isophthalic acid, TPA: terephthalic acid, AA: adipic acid
Viscosity: 50% solution (25℃ Gardner), Molecular weight: Weight average molecular weight (GPC)

Examples and comparative examples of B resin according to the present invention division Example 1 Example 2 Example 3 Example 4 Comparative example
alcohol EG 2.0 - 2.0 2.0 - NPG 10.0 14.0 13.0 20.0 - 1.6HD 27.0 25.0 25.0 18.0 - TMP 1.0 1.0 1.0 - -
mountain IPA 33.0 34.0 30.0 35.0 - TPA 20.0 21.0 23.0 19.0 - AA 7.0 5.0 7.0 6.0 - Additive (Fascat 4100) 0.1 0.1 0.1 0.1 - specific gravity 1.05 1.05 1.05 1.05 - viscosity Z3 Z4 Z3 Z4 - Solid content 38.5 37.2 40.1 40.5 - Mountain 1.5 1.6 1.1 1.2 - Molecular weight 24,200 25,400 26,400 27,000 - Hydroxyl value 18 20 19 20 - NPG: neopentyl glycol, EG: ethylene glycol, 1,6HD: 1,6 hexanediol, TMP: trimethylolpropane
IPA: isophthalic acid, TPA: terephthalic acid, AA: adipic acid
Viscosity: 40% solution (25℃ Gardner), Molecular weight: Weight average molecular weight (GPC)

Comparison table of properties of A resin and B resin according to the present invention and conventional top-coat resin division A Suzy B resin Conventional commercial resin Solid content (%) 35 40 60 viscosity W-Y Z3-Z5 V-X Molecular weight 20,000 - 30,000 20,000 - 30,000 11,000 -13,000 Hydroxyl value 20-40 10-30 10-60 Glass transition temperature (Tg) 10-20℃ 50-70℃ 20-40℃

<Solvent>

The paint composition according to the present invention contains 10 to 20 wt% of an organic solvent with respect to the entire composition, taking into consideration the characteristics during handling and coating work.

As the above organic solvent, it is preferable to use an appropriate mixture of aromatic hydrocarbon solvents, glycol ester solvents, glycol ether solvents, alcohol solvents, etc.

As the above aromatic hydrocarbon solvent, SK's Cocosol #100 and Cocosol #150 can be used.

And as the above glycol ester solvent, ethyl acetate, n-butyl acetate, cellosolve acetate, propylene glycol monomethyl acetate, 3-methoxy butyl acetate, etc. from Union Carbide can be used.

And as the above glycol ether solvent, Union Carbide's methyl cellosolve, ethyl cellosolve, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, etc. can be used.

And as the alcohol solvent, ethanol, isopropanol, n-butanol, amyl alcohol, cyclohexanol, etc. can be used.

<Bridge>

The paint composition according to the present invention uses melamine resin as a crosslinking agent for forming a coating film with the above-mentioned resin component.

When the above melamine resin is applied alone, the coating strength is excellent, but the processability and adhesion of the coating are relatively low.

To overcome these shortcomings, a resin with high flexibility is used and the ratio of monomers in the resin with excellent adhesion is adjusted.

That is, a methyl etherified melamine resin having a methoxy group is used as the crosslinking agent, and is contained in an amount of 5 to 10 wt% with respect to the entire composition.

<Pigment>

The paint composition according to the present invention contains a coloring pigment.

As the above coloring pigment, it is preferable to use titanium oxide centered on carbon black, which is used in the field of coating compositions.

Here, it is preferable that the pigment is contained in an amount of 2 to 5 wt% with respect to the entire paint composition.

<Curing catalyst>

As a curing catalyst, one sulfonic acid (p-TSA) selected from p-toluene sulfonic acid (p-TSA), dinonylnaphthalene sulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA), and fluoro sulfonic acid is used by diluting it in isopropanol.

It is preferable that the above-mentioned curing catalyst be contained in an amount of 1 to 2 wt% with respect to the entire paint composition.

If the content of the above curing catalyst exceeds 2 wt%, the curing density within the paint increases, which reduces processability, and if it is less than 1 wt%, there is a problem in that the degree of curing of the coating film decreases.

<Interlayer adhesive>

The paint composition according to the present invention uses a polysiloxane copolymer or a low molecular weight unsaturated polycarboxylic acid polymer to improve interlayer adhesion.

It is preferable that the interlayer adhesive be contained in an amount of 0.5 to 2 wt% with respect to the entire paint composition.

Here, if the content of the interlayer adhesive exceeds 2 wt%, it causes a phenomenon of thickening or seeding during use, which reduces storage stability, and if it is less than 0.5 wt%, the interlayer adhesive effect becomes minimal.

<Leveling agent and foaming agent>

The paint composition according to the present invention contains 0.5 to 1.0 wt% of an acrylic, vinyl or silicone leveling agent and defoaming agent, respectively, to maintain the smoothness of the coating film and improve the defoaming property during painting.

As the above leveling agent and defoaming agent, Disparon L-1980, Disparon L-1984, Disparon AP-30 from Kusumoto Chemical Co., Ltd., BYK356, BYK410, etc. can be used.

<Other additives>

The paint composition of the present invention may further contain talc, clay, silica, mica, alumina, etc.

Below, the specimen specifications and painting conditions for testing the paint composition according to the present invention are described.

First, a 0.8 mm thick non-chromium (NON-CR) zinc-magnesium-aluminum alloy plated steel sheet was used as the test plate.

And the dry film thickness was 7 ㎛ for the primer and 18 ㎛ for the top coating, and the primer was dried at 216℃ and the top coating was dried at 232℃ to prepare a material property test specimen.

[Table 4] below shows the paint composition of test specimens of Examples 1 to 4 according to the present invention.

Paint compositions of examples 1 to 4 according to the present invention Composition (weight%) Example 1 Example 2 Example 3 Example 4 A Suzy 20 25 30 35 B resin 40 35 30 25 Dispersing additives 1.0 1.0 1.0 1.0 Carbon Black 5 5 5 5 Other pigments 1 1 1 1 Silica 0.5 0.5 0.5 0.5 Melamine 6 6 6 6 Leveling agent 1.0 1.0 1.0 1.0 Acid catalyst 1.0 1.0 1.0 1.0 parcel 1.0 1.0 1.0 1.0 Adhesion enhancer 1.5 1.5 1.5 1.5 DBE 10 10 10 10 CYCLOHEXANONE 6 6 6 6 KOCOSOL 150 6 6 6 6

Next, the following tests were conducted on the test specimens of Examples 1 to 4.

<Gloss>

After setting the angle to be measured on the gloss meter and calibrating the value with a standard plate, foreign matter on the test specimen was removed and the gloss was measured.

<hardening degree>

The test specimen was placed horizontally and held in place with one hand, and an appropriate amount of solvent (METHYL ETHYL KETONE) was applied to a gauze wrapped around the finger with the other hand and the coating surface was rubbed up and down until the material was exposed, which ended the test and the number of times up to this point was measured.

<Pencil Hardness>

The test specimen was fixed to the pencil hardness tester, and the pencil was sharpened so that the tip was smooth and the angle was sharp so that the lead was exposed by about 3 mm, and then it was fastened to the hardness tester at a 45 degree angle.

Next, a load of 1 kg was applied, and a line was drawn 5 times to a length of 20 mm or more. The test area was erased with an eraser and observed with the naked eye.

<Processability>

After manufacturing the test specimen according to the EN 23270;1991 test method, 180-degree T-Bending was performed using a vice.

At this time, the processability was evaluated by attaching a transparent adhesive tape to the processing area and then removing it at a 60-degree angle at a uniform speed of 0.5 to 1 second.

<Adhesion>

After fixing the test specimen on a flat surface, the adhesion was evaluated by scratching the test specimen with a coin at an angle of 30 to 45 degrees for a distance of 20 mm or more.

<Pharmaceutical>

After wrapping the cut surface of the test specimen with a tape that can withstand the reagent and the test period, 5% HCl reagent was added to the beaker and the test specimen was completely immersed without contacting the beaker. After 24 hours, it was taken out, washed with water, dried, and observed for any abnormalities.

<Corrosion resistance>

The test was conducted according to the salt spray test standard of ASTM D B1117.

The cut surface of the test specimen was protected by sealing it with tape, and an X-shaped scratch was made on the flat surface with a cutter. After 2000 hours, the degree of white rust and blisters on the flat surface of the test specimen was observed.

<Water resistance>

The test specimen was immersed in distilled water at 40°C for 720 hours, then taken out and cross-cut to evaluate the peeling area.

<Paint storage>

As there is no standardized test method for paint storability, we conducted our own test in the following manner to suit the characteristics of this PCM paint.

First, the gloss, appearance, and degree of curing of the test specimen were checked, and after leaving it in a box oven at 50 degrees for 7 days, the degree of change in gloss, appearance, color difference, and degree of curing was observed.

[Table 5] below summarizes the test results for the test specimens of Examples 1 to 4.

Test results of examples 1 to 4 according to the present invention Composition (weight%) Example 1 Example 2 Example 3 Example 4 specific gravity 1.06 1.06 1.05 1.05 Solid content 37.0 37.0 36.5 36.5 Viscosity (sec/25'C) 100 100 100 100 Glossiness 50 50 50 50 Hardening degree 50 50 50 50 Pencil hardness HB HB HB HB Processability △ ○ ○ ◎ Adhesiveness ◎ ○ ○ ○ Pharmaceutical △ △ ○ ○ Corrosion resistance ○ ○ ◎ ◎ Water resistance △ △ ◎ ◎ Paint storage capacity ◎ ◎ ◎ ◎

(◎: Excellent, ○: Good, △: Average)

As can be seen from [Table 5] above, the test specimen of Example 4 was found to have the best properties.

In addition, when the PCM paint composition according to the present invention was applied to a 0.8 mm thick non-chromium (NON-CR) hot-dip zinc-magnesium-aluminum alloy plated steel sheet, it was confirmed that the workability, corrosion resistance, chemical resistance, adhesion, and water resistance were maintained at an equivalent or higher level compared to conventional electrodeposition coating.

Therefore, when the PCM paint composition according to the present invention is applied to a steel plate for manufacturing an automobile fuel pump cover, the amount of waste generated during the painting process can be significantly reduced since electrodeposition painting does not need to be performed.

This can reduce environmental pollution and actively contribute to the company's ESG management.

In addition, the paint composition according to the present invention can improve the adhesion of the paint and processability at the same time when manufacturing an automobile fuel pump cover by mixing and using resin A, which can increase flexibility as a main resin, and resin B, which can improve adhesion.

Accordingly, when an automobile fuel pump cover is manufactured using the paint composition according to the present invention, the manufacturing cost can be lowered by reducing the work man-hours, and productivity can be greatly improved.

The above has been described as an example of a preferred embodiment of the present invention, and the scope of the present invention is not limited to the specific embodiments described above.

Anyone skilled in the art will appreciate that various modifications and changes can be made without departing from the scope of the technical idea of the present invention.

10: Steel plate 20: Pretreatment layer
30: Lower coating layer 40: Upper coating layer

Claims (9)

A paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, comprising a polyester resin, a solvent, a crosslinking agent, a pigment, a curing catalyst, an interlayer adhesive, a leveling agent, and an antifoaming agent,
The above polyester resin is,
It is composed of A resin to enhance flexibility and improve processability, and B resin to improve adhesion.
The above A resin is,
The molecular weight is 20,000 to 30,000, the hydroxide value is 20 to 40 mgKOH/g, the acid value is 1 to 5 mgKOH/g, and the glass transition temperature is 5 to 15°C, and is contained in an amount of 30 to 40 wt% with respect to the entire paint composition.
The above B resin is,
A paint composition of a PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that the paint composition contains 40 to 60 wt% of an aromatic component, has a weight average molecular weight of 20,000 to 30,000, an acid value of 10 to 30 mgKOH/g, an acid value of 1 to 3 mgKOH/g, and a glass transition temperature of 50 to 70°C, and is contained in an amount of 20 to 40 wt% based on the total paint composition. In paragraph 1,
A paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that the molecular structure of the above A resin contains 25 to 30 wt% of one monomer selected from propanediol, 1,6 hexanediol, and 1,4 butanediol. In paragraph 1,
A paint composition for a PCM steel plate for manufacturing an automobile fuel pump cover, characterized in that the solvent is contained in an amount of 10 to 20 wt% with respect to the entire paint composition. In paragraph 1,
The above cross-linking agent is,
A paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that a methyl etherified melamine resin having a methoxy group is contained in an amount of 5 to 10 wt% with respect to the entire paint composition. In paragraph 1,
The above pigments are,
A paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that it contains 2 to 5 wt% of titanium oxide centered on carbon black with respect to the entire paint composition. In paragraph 1,
The above curing catalyst is,
A paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that the paint composition comprises 1 to 2 wt% of a neutralized product obtained by neutralizing any one sulfonic acid selected from p-toluene sulfonic acid (p-TSA), dinonylnaphthalene sulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA), and fluoro sulfonic acid with a secondary amine or epoxy, based on the total paint composition. In paragraph 1,
The above interlayer adhesive is,
A paint composition for a PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that it contains 0.5 to 2 wt% of a polysiloxane copolymer or a low molecular unsaturated polycarboxylic acid polymer based on the total paint composition. In paragraph 1,
A paint composition for a PCM steel plate for manufacturing an automobile fuel pump cover, characterized in that the leveling agent and the defoaming agent are each contained in an amount of 0.5 to 1 wt% with respect to the entire paint composition. A PCM steel plate to which a paint composition according to any one of claims 1 to 8 is applied,
A PCM steel sheet for manufacturing an automobile fuel pump cover, characterized in that it comprises a steel sheet (10), a pretreatment layer (20) formed on both sides of the steel sheet (10), a base coating layer (30) formed on the pretreatment layer (20) on both sides, and a top coating layer (40) formed on both sides of the base coating layer.