KR20150124814A - Primer for color steel sheet and method of manufacturing color steel sheet using the same - Google Patents

Abstract

Disclosed are a paint for a high weather resistance color steel plate having an excellent heat-insulting property and a method for manufacturing a color steel plate using the same. A paint for a color steel plate according to the present invention comprises a solid and a solvent, wherein the solid comprises an inorganic paint of 5 to 40 parts by weight and an ultraviolet ray absorbent of 1 to 5 parts by weight based on a polyester resin of 100 parts by weight having average molecular weight of 20,000 or more.

Description

TECHNICAL FIELD [0001] The present invention relates to a paint for a color steel plate, and a method for manufacturing a color steel plate using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002]

More particularly, the present invention relates to a paint for a high-weathering color steel sheet excellent in heat-insulating performance when applied to a roofing material, and a method for manufacturing a color steel plate using the same.

Colored steel sheets are widely used in construction materials such as construction materials such as household appliances such as washing machines, refrigerator, freezing facilities, food processing facilities, and roofs.

The color steel sheet is produced by a method of sequentially forming a pretreatment layer, a subbing layer and a top layer on the surface of a steel sheet, and usually includes a pigment exhibiting a target color on the upper layer.

The pretreatment layer is a pretreatment agent containing chromium or a pretreatment agent containing no chromium.

The undercoat layer is mainly formed for improving the adhesion and corrosion resistance, and the oil-based undercoat is mainly used.

The top layer is formed for corrosion resistance and color development, and oily or water-based paints containing pigments are used.

Background art related to the present invention is a colored steel sheet for household appliances disclosed in Korean Patent Laid-Open Publication No. 10-2007-0025223 (published on Mar. 3, 2007) and a method for manufacturing the same.

It is an object of the present invention to provide a paint for a color steel plate capable of producing an ultra-high weatherability color steel sheet excellent in heat shielding performance.

Another object of the present invention is to provide a method of manufacturing an ultra-weatherproof color steel sheet having excellent heat shielding performance by using the paint.

In order to accomplish the above object, there is provided a paint for a color steel plate according to an embodiment of the present invention, comprising 100 parts by weight of a polyester resin having a solid content and a solids content of 20,000 or more and a weight average molecular weight of 20,000 or more, 5 to 40 parts by weight of pigment and 1 to 5 parts by weight of UV absorber.

At this time, the paint for a color steel plate may have a solid content of 60 to 75% by weight and a solvent of 25 to 40% by weight.

In addition, the UV absorber may be selected from benzophenone, benzotriazole, oxanilide, and benzoate.

According to another aspect of the present invention, there is provided a method of manufacturing a color steel sheet, including: forming a pretreatment layer on a base steel sheet; Forming a primer layer on the pretreatment layer; And forming an upper layer on the lower layer, wherein at least one of the upper layer forming step and the lower layer forming step comprises a solid content and a solvent, and the solid content of the polyester resin having a weight average molecular weight of 20,000 or more 5 to 40 parts by weight of an inorganic pigment coated with chromium-containing hematite, and 1 to 5 parts by weight of a UV absorber are applied and dried, based on 100 parts by weight of the composition.

At this time, it is preferable that the undercoat layer is formed to a thickness of 3 to 7 mu m, and the uppermost layer is formed to a thickness of 15 to 25 mu m.

According to the method for producing a color steel sheet using a paint for a color steel plate according to the present invention, the heat-shrinking performance is excellent by including an inorganic pigment and a UV absorbent having a weight-average molecular weight of 20,000 or more super polyester as a main component and excellent in heat- , A colored steel sheet which can exhibit excellent weather resistance can be produced.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a paint for a color steel sheet according to the present invention and a method for manufacturing a color steel sheet using the same will be described in detail.

Coating for color steel plate

The paint for a color steel sheet according to the present invention includes a solid content and a solvent. More specifically, the paint for a color steel sheet according to the present invention comprises 60 to 75% by weight of a solid content and 25 to 40% by weight of a solvent.

At this time, the paint for a color steel plate according to the present invention contains a polyester resin having a weight-average molecular weight of 20,000 or more as a main component, and 100 parts by weight of a polyester resin having a weight average molecular weight of 20,000 or more. The chromate-containing hematite- To 40 parts by weight and 1 to 5 parts by weight of UV absorber.

Hereinafter, the role and content of the components included in the paint for a color steel sheet according to the present invention will be described.

Polyester resin

The polyester resin is a main component of the coating film. The polyester resin is excellent in corrosion resistance and adhesion.

In the present invention, a polyester having a weight average molecular weight of 20,000 or more is used. The polyester having such a condition has a strong bonding force in the molecule and can exhibit resistance to ultraviolet rays and moisture penetration, and is excellent in thermal stability, and the weather resistance of a color steel sheet can be greatly improved.

In order to improve the weather resistance, a paint mainly composed of a fluororesin has been used. However, in the case of a fluororesin, expensive resins have been a factor for increasing the cost of a colored steel sheet. In the case of a paint for a color steel plate, it is possible to significantly reduce the cost of manufacturing a color steel plate.

Inorganic pigments

Inorganic pigments are included to express the desired color. Particularly, in the present invention, the pigment provides a heat reflecting effect, so that cooling and heating energy saving effect of the building can be obtained. As the inorganic pigment having such a function, an inorganic pigment coated with chromium-containing hematite is used in the present invention.

In addition, the above inorganic pigments have a strong binding force as compared with the organic pigments. In the case of organic pigments, the carbon-carbon bonds may be broken in the visible light region to deteriorate the weatherability. However, the inorganic pigments do not inhibit the weatherability even if they are exposed to visible light for a long time through strong bonding force several times or more. In addition, organic pigments have a problem of reacting with a resin due to surface activity, but inorganic pigments are more stable than organic pigments because of their surface inertness.

The chromium-containing hematite-coated inorganic pigment is preferably included in an amount of 5 to 40 parts by weight based on 100 parts by weight of the polyester resin. When the content of the inorganic pigment is less than 5 parts by weight, the effect is insufficient. On the other hand, when the content of the inorganic pigment exceeds 40 parts by weight, the adhesion of the coating film may be deteriorated.

UV absorber

UV absorbers are materials that absorb high energy UV absorption and release the absorbed energy into non-destructive energy, contributing to the improvement of weatherability.

Such UV absorbers may be selected from benzophenone, benzotriazole, oxanilide and benzoate.

The UV absorber is preferably contained in an amount of 1 to 5 parts by weight based on 100 parts by weight of the polyester. When the content of the UV absorber is less than 1 part by weight, the effect of the addition is not sufficiently exhibited. On the contrary, when the content of the UV absorber is more than 5 parts by weight, weatherability may be deteriorated.

solvent

The solvent is used for securing the coating property through viscosity control, and one or more kinds of solvents such as alcoholic solvents such as isopropyl alcohol, ketone solvents such as cyclohexanone, and the like can be used.

The solvent is preferably contained in an amount of 25 to 40% by weight of the total weight of the coating material. When the content of the solvent is out of the above range, the viscosity becomes excessively high or low, which is not preferable from the viewpoint of coatability or productivity.

Color steel plate manufacturing method

A method of manufacturing a color steel sheet according to the present invention includes sequentially forming a pretreatment layer, a primer layer, and a top coat layer on a base steel sheet.

The base steel sheet may be a hot-rolled steel sheet having a thickness of about 0.2 to 1 mm, a cold-rolled steel sheet or a hot-dip galvanized steel sheet, a galvannealed galvanized steel sheet, or an electro-galvanized steel sheet.

As the pretreatment agent, any known trivalent chromate-based pretreatment agent or chromium-free pretreatment agent can be used without limitation.

At least one of the upper layer forming step and the lower layer forming step may be performed by applying and drying the above-mentioned coating material to form a primer layer or a top layer. Most preferably, both the upper layer and the lower layer use the above-mentioned paint, but when the above-mentioned paint is applied to only one of the layers, the other layer is a known paint or a resin of a known paint with a weight average molecular weight of 20,000 or more Ester can be applied.

On the other hand, it is preferable that the undercoat layer is formed to a thickness of 3 to 7 mu m and the uppermost layer is formed to a thickness of 15 to 25 mu m. It is easy to secure excellent adhesion and corrosion resistance in the above thickness range.

The drying for forming the top layer and the undercoat layer may be performed by a method of hot air drying at approximately 210 to 240 ° C for 3 to 7 seconds.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Preparation of specimens

Example 1

A trivalent chromate treatment agent was coated on the hot-dip galvanized steel sheet and hot-air dried at a temperature of 80 占 폚 for PMT (Peak Metal Temperature) to form a pretreatment layer having a thickness of about 2 占 퐉. Then, a solid content: solvent Hexanone 1: 1) at a weight ratio of 68:32 and a solid content of 100 parts by weight of a polyester resin having a weight average molecular weight of 40,000 was coated with a paint comprising 20 parts by weight of TiO2 and 2 parts by weight of benzophenone, Followed by hot air drying for 5 seconds to form a coating film having a thickness of 20 탆.

2. Property evaluation method

A method of evaluating the physical properties of a color steel plate specimen produced according to Example 1 is as follows.

(1) Abrasion resistance

The abrasion resistance of the gauze was evaluated by evaluating whether resin peeling or swelling occurred after MEK (Methyl Ethyl Ketone) was applied to the gauges and rubbed 100 times with 1 kgf force.

Good (O): No resin peeling or swelling

Defective (X): resin peeling or swelling occurs

(2) Hardness

The hardness was measured by measuring the pencil hardness.

(3) Impact resistance

The impact resistance was evaluated by whether or not a crack occurred after the surface impact by dropping the weights under the condition of 1/2? X 1 kg x 500 mm.

Good (O): No cracks

Bad (X): Cracked

(4) Processability

The T-bending test was carried out to determine whether the bending radius of the specimen occurred at twice the specimen thickness.

Good (O): No cracks

Bad (X): Cracked

(5) Corrosion resistance

The corrosion resistance of the specimens was evaluated by 500 hours and 1000 hours of neutral salt spray test after X-cutting, and then film peeling, corrosion of the plated surface, presence of rust, and blister size were confirmed. The evaluation criteria are as follows.

Good (O): Peeling of coating film, corrosion of plated surface, no rust, blister 3 mm or less

Defective (X): Exfoliation of coating film, peeling, corrosion of plated surface or rusting, blister exceeding 3mm

(6) Weatherability

Weatherability was measured by measuring G.R (%) and ΔE by WOM (weather ometer) and QUV (Quick Ultra Violet) test (1,000 hours, 2,000 hours, respectively) Good standards are as follows.

1,000 hours WOM test: G.R (%) Within 45 ± 5%, ΔE: Within 2.5

2,000 hours WOM test: G.R (%) Within 10 ± 1%, ΔE: Within 3.0

1,000 hours QUV test: G.R (%) within 80 ± 8%, E: below 0.8

2,000 hours QUV test: GR (%) within 70 ± 7%, ΔE: 1.5 or less

(7) Thermal performance

The thermal performance was measured by TSR (Total Solar Reflectance) and TE (Thermal Emittance) tests.

Good standards are as follows.

TSR: 25% or more

TE: 83% or more

3. Results of physical property evaluation

The evaluation results of the physical properties of Example 1 based on the evaluation criteria are shown in Table 1.

[Table 1]

Referring to Table 1, it can be seen that the coating film prepared according to Example 1 has a passing point in all properties such as abrasion resistance, workability, weather resistance, and heat resistance.

As described above, the conventional paint is manufactured on the basis of a high-priced fluororesin. However, even when manufactured on the basis of a polyester resin having a weight average molecular weight of 20,000 or more as described above, It is possible to greatly reduce the manufacturing cost of the weather-resistant colored steel plate.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of protection of the present invention should be defined by the following claims.

Claims (5)

And 5 to 40 parts by weight of an inorganic pigment coated with chromium-containing hematite and 1 to 5 parts by weight of a UV absorber, based on 100 parts by weight of a polyester resin having a solid content and a solid content of 20,000 or more in weight average molecular weight, Paint for color steel plate.
The method according to claim 1,
Wherein the UV absorber is selected from benzophenone, benzotriazole, oxanilide and benzoate.
The method according to claim 1,
The paint for the color steel plate
A solid content of 60 to 75% by weight and a solvent content of 25 to 40% by weight.
Forming a pretreatment layer on the base steel sheet;
Forming a primer layer on the pretreatment layer; And
Forming a top coat layer on the undercoat layer,
Wherein at least one of the upper layer forming step and the lower layer forming step is a step of forming an inorganic pigment layer containing chromium-containing hematite on the basis of 100 parts by weight of a polyester resin having a solid content and a weight average molecular weight of 20,000 or more, And 1 to 5 parts by weight of a UV absorber is applied and dried.
5. The method of claim 4,
The undercoat layer is formed to a thickness of 3 to 7 mu m,
Wherein the upper layer is formed to a thickness of 15 to 25 占 퐉.