KR101787535B1 - Coating Composition of Transparent Color-Painted Stainless Steel Sheet for Pre-Coating Metal and Stainless Steel Sheet Therof - Google Patents

Abstract

The present invention relates to a coating composition for a transparent colorless coated stainless steel coated steel sheet for PCMC and a coated steel sheet produced thereby, The goal is to make the texture visible to the outside.
The present invention provides a paint composition for producing a stainless steel coated steel sheet coated with a stainless steel material for PCM (Pre-Coated Metal), comprising a main resin, a hardener, a pigment, a solvent and an additive (Acrylic Resin) having an OH value of 0 to 6.0, a molecular weight (Mn) of 3,000 to 150,000 and a glass transition temperature (Tg) of 50 to 110 ° C as the main resin, By weight based on the total coating composition, and 35% by weight of the pigment. The colorant comprises a pigment dispersed in a nano-sized pigment as a main component in an amount of 1.0 to 7.0% by weight based on the total coating composition.

Description

Technical Field The present invention relates to a coating composition for a transparent colorless coated stainless steel re-coated steel sheet for PCM and a coated steel sheet produced by the method.

The present invention relates to a coating composition for a transparent colorless coated stainless steel coated steel sheet for PCM (Pre-Coated Metal) used for manufacturing housings of various home appliances such as a refrigerator, a washing machine, a microwave oven, and a stainless steel coated steel sheet More particularly, the present invention relates to a colorant which uses a colorant mainly composed of nano-sized dispersed pigments in an acrylic resin and an amino resin, And it is possible to satisfy the harsh processing conditions by making the hair line (Metal) texture of the stainless steel material to be exposed to the outside well and being excellent in moldability and physical properties. The present invention relates to a coating composition for a steel sheet and a coated steel sheet produced thereby.

In the steel plate coating method, there are a post-coating method in which a steel plate is molded and then a pre-coating method in which a steel plate is coated before molding.

The post coating method is disadvantageous in that it is inexpensive in facility cost and is advantageous in small quantity production but it is difficult to produce uniform product and mass production.

On the other hand, the precoating method has an advantage that a uniform product can be produced, loss of paint is small, and mass production can be performed in a short time.

The steel sheet coated with the above-described pre-coating method is referred to as a pre-coated steel sheet, and the coating used for precoating is called a PCM coating.

The PCM steel sheet painted by the above-mentioned PCM paint is subjected to a separate processing step after coating.

Accordingly, the PCM paint should satisfy conditions such as excellent processability, hardness of the coating film, adhesion, weatherability, corrosion resistance and curability.

On the other hand, stainless steel is mainly used as a housing material of household appliances such as a refrigerator, a washing machine, and a microwave oven, and a PCM coated steel plate having a color coating on the surface of stainless steel is widely used.

However, the conventional stainless steel coated steel sheet for PCM has a disadvantage in that the coating film is not transparent and translucent.

That is, according to the conventional PCM paint, the coating film is in a translucent state which is not transparent, and there is a problem that the hair line texture and the metal texture inherent to the stainless steel material formed by the polishing process are not expressed externally.

Further, according to the conventional PCM paint, there is a problem in that it can not satisfy severe molding conditions and physical properties in the manufacture of housings of home appliances.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, and to provide a stainless steel sheet for PCM that can impart color to the steel sheet while maintaining transparency of the coated film.

Another object of the present invention is to make the colored coating film of the stainless steel coated steel sheet for PCM to maintain transparency and to make the fine hair lines (the hair line and the metal texture) formed by the polishing process well visible to the outside.

Still another object of the present invention is to satisfy harsh molding conditions when manufacturing a household appliance housing with a stainless steel coated steel sheet for PC.

It is another object of the present invention to provide a stainless steel coated steel sheet for PCM capable of maintaining high mechanical strength and high mechanical strength.

In order to achieve the above-mentioned object, the present invention provides a method of manufacturing a colorless stainless steel coated steel plate for a PCM (Pre-Coated Metal), which comprises a main resin, a curing agent, a pigment, a solvent and an additive, (Acrylic Resin) having OH of 0 to 6.0, a molecular weight (Mn) of 3,000 to 150,000, and a glass transition temperature (Tg) of 50 to 110 캜 is used as the main resin, The colorant is contained in an amount of 15 to 35% by weight based on the composition, and the pigment is contained in an amount of 1.0 to 7.0% by weight based on the total coating composition, the colorant comprising a pigment dispersed in a nano size as a main component .

Also, as the above-mentioned curing agent, a hexamethoxymethylmelamine type resin having a solid content (NV: Non Volatile) of 98% or more is contained in an amount of 1.0 to 15.0% by weight based on the total coating composition.

Also, as the above-mentioned curing agent, benzoguanamine having a solid content of 80% or more is contained in an amount of 1.0 to 15.0% by weight based on the total coating composition.

Further, the solvent is characterized in that an aliphatic hydrocarbon-based or ester-based solvent is contained in an amount of 20 to 60% by weight based on the total coating composition.

According to the present invention, transparency of a coated film can be maintained while imparting hue to a stainless steel coated steel sheet for PCM, thereby realizing a transparent colored coating layer.

Further, since the colored coating film of the stainless steel re-coated steel sheet for PCM can maintain transparency, there is an effect that the fine hair lines ((Hair Line) and the metal texture on the surface of the stainless steel material formed by the polishing process are exposed to the outside.

In addition, it has an effect of satisfying harsh molding conditions in the manufacture of housings of various home appliances such as a refrigerator, a washing machine, and a microwave oven.

In addition, the coating film can maintain mechanical properties of high porosity and high hardness, so that it is possible to manufacture a stainless steel coated steel sheet for a high quality PFC.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic sectional view of a transparent color coated stainless steel coated steel sheet for PCM according to the present invention.
FIG. 2 is a photograph of an actual product coated with a paint according to the present invention on a hairline-treated stainless steel material. FIG.
FIG. 3 is a photograph of an actual product formed by a refrigerator door using a steel plate painted with a paint according to the present invention on a hairline-treated stainless steel material.

The inventors of the present invention have made efforts to develop coating compositions for painted stainless steel coated steel sheets for PCM which satisfy severe molding conditions in the production of household appliances housings and ensure transparency. As a result, they have been able to maintain transparency while imparting colors, A transparent and transparent coloring composition that allows the hairline texture and the metal texture of the linseed material surface to be exposed to the outside has been developed.

The coating composition of the transparent colorless coated stainless steel coated steel sheet for PCM according to the present invention comprises a main resin, a curing agent, a pigment, a solvent and an additive, and is coated with a stainless steel material for PCM (Pre-Coated Metal) A coating composition for producing a colorless coated stainless steel re-coated steel sheet, characterized in that an acrylic resin having an OH of 0 to 6.0, a molecular weight (Mn) of 3,000 to 150,000 and a glass transition temperature (Tg) of 50 to 110 ° C Acrylic Resin) is contained in an amount of 15 to 35% by weight with respect to the total paint composition, and the colorant comprising a pigment dispersed in a nano size as a main component is contained in an amount of 1.0 to 7.0 wt% %.

Accordingly, transparency of the coated film can be maintained while imparting color to the surface of the substrate steel, and the hairline and the metal texture of the surface of the stainless steel can be expressed externally.

In addition, since the high porosity is ensured, severe molding conditions can be satisfied in the manufacture of the housing of the household appliance, and the physical properties of the coating film are excellent, so that a high-quality appearance can be realized.

As the curing agent, a hexamethoxymethylmelamine resin having a NV (non volatile) of 98% or more, or a benzoguanamine having a NV (nonvolatile) of 80% By weight based on the total weight of the composition.

As the above-mentioned solvent, an aliphatic hydrocarbon-based or ester-based solvent is preferably contained in an amount of 20 to 60% by weight based on the total coating composition.

The acrylic additive may be contained in an amount of 1.0 to 2.0% by weight and the wax (WAX) may be contained in an amount of 0.01 to 0.5% by weight.

Each component of the coating composition according to the present invention will be described below.

<Acrylic Resin>

The main resin used in the present invention is preferably an acrylic resin having an OH of 0 to 6.0, a glass transition temperature (Tg) of 50 to 110 ° C and a molecular weight (Mn) of 3,000 to 150,000.

If the molecular weight of the acrylic resin is too small, the coating film breaks at the curved portion at the time of processing, and if the glass transition temperature is too low, the hardness of the coating film tends to be lowered.

[Table 1] below shows preferable physical properties of the acrylic resin applied to the present invention.

 The physical properties of the acrylic resin according to the present invention division Resin Properties Remarks Solid 15 to 35% OH Value 0 to 6.0 Molecular weight (Mn) 3,000 ~ 150,000 The glass transition temperature (Tg) 50 to 110 ° C

<Curing agent>

Hexamethoxymethylmelamine amino resin or benzoguanamine is contained in an amount of 1.0 to 15.0% by weight based on the total coating composition as a curing agent for curing an acrylic resin as a main resin.

When the content of the curing agent is less than 1.0% by weight based on the total coating composition, the curing is deteriorated. When the content of the curing agent is more than 15.0% by weight, the bending property of the coating film is deteriorated.

<Pigment>

The pigment used in the present invention is preferably a colorant containing a dispersed pigment as a main component in a nano size and is preferably contained in an amount of 1.0 to 7.0% by weight based on the total coating composition.

<Solvent>

An appropriate amount of an organic solvent is contained in consideration of the handling of the coating composition and the characteristics of the coating operation.

The organic solvent preferably contains an aliphatic hydrocarbon-based or ester-based solvent in an amount of 20 to 60% by weight based on the total coating composition.

Hereinafter, a test method and a test result using the paint according to the present invention will be described.

First, a 0.5 T stainless steel plate was degreased with KOH (degreasing agent), and after applying the pretreatment, the paint according to the present invention was made to have a dry film thickness of 6.5 탆 (including 1.5 탆 below). .

Table 2 below shows the composition ratios of the coating compositions applied to the test specimens.

Composition ratio of coating composition applied to test specimen division Composition ratio (% by weight) Remarks Acryl Resin 20 ~ 30 Hardener
(Hexamethoxymethylmelamine) 5 to 10 Pigment 4 to 7 solvent 55 ~ 65 additive 1-2

Then, the physical properties of the coating film on the following items were evaluated by the test specimens.

<Film Thickness>

The coating on the site to be measured was removed and a zero point was set on the work plane using a measuring device. Then, the thickness of the standard plate was set, and the average value was calculated by measuring five times in the circumferential direction near the coating removal area.

<Glossiness>

The angle to be measured was set on the gloss meter, the value was corrected using a standard plate, the foreign matter of the test plate was removed, and the gloss was measured.

<Pencil hardness>

The test plate was fixed to the pencil hardness tester, and the pencil was cut so that the core was exposed to about 3 mm, and the end was smooth and the angle was sharpened.

The pencil was bound to the hardness tester at an angle of about 45 °, and a line was repeatedly drawn five times so that the length was 20 mm or more by applying a load of 1 kg. The test area was erased with an eraser and observed with the naked eye.

<Processability>

According to the test method of EN 23270; 1991, T-Bending was performed at room temperature using a vise at 2T. Subsequently, using a transparent adhesive tape, a tape having a length of approximately 75 mm was stuck to the processing region and peeled off at a uniform angle of 60 ° between 0.5 and 1 second to evaluate the processability.

<C.CT>

100 checkerboard patterns were made at intervals of 1 mm using a cross cut on the surface of the test specimen. After wiping the coated film, a 25 mm cellophane tape was closely adhered to the test piece, and then quickly peeled off in the opposite direction (180 degrees) And it was observed whether or not it fell off. The cellophane tape used was NZIBAN CELLOPHANE TAPE NO.1125.

<C.E.T>

100 checkerboard patterns were made at intervals of 1 mm using a cross cut on the surface of the test specimen and operated to a length of 1 mm / sec with an Erichsen tester.

The cellophane tape was adhered to the coating film of the test part and then quickly peeled off in the opposite direction (180 °) to observe whether or not the coating film was peeled off. The cellophane tape used was NZIBAN CELLOPHANE TAPE NO.1125.

<Impact>

The impact weight was dropped in accordance with the conditions of the impact rod diameter 1/2 inch (12.7 mm), drop weight 1 kg, drop height 50 cm, and the presence of cracks in the deformation area was confirmed. In addition, the cellophane adhesive tape was adhered to the deformed part according to the test conditions, and then peeled off quickly to observe the peeling of the film.

<Contamination resistance>

After the coating was applied to the coating film, the test piece was observed for 24 hours at 30 ° C.

<Ultraviolet ray resistance>

The test specimens conforming to ASTM G154 were tested for 24 hours, and then the color difference of the test specimens was measured.

<Alkali resistance>

The cut surface of the specimen is fully protected with reagents and tape or paint to withstand the test period, the 5% Na2CO3 reagent is placed in the beaker, the specimen is fully immersed for 24 hours to avoid contact with the beaker, the specimen is taken out, And abnormalities were observed.

<Acid resistance>

The cut surface of the specimen was completely protected with reagents and tape or paint to withstand the test period, the 5% CH3COOH reagent was added to the beaker, the specimen was completely immersed for 24 hours so as not to contact the beaker, and the specimen was taken out, And abnormalities were observed.

<Sea water, etc.>

The temperature of the hot water bath was maintained at 98 ± 2 ℃, and the specimens were placed in a constant temperature water bath. After 1 hour, the hot water bath was taken out and rinsed with water.

<Moisture resistance>

The conditions of the wet tester were set at 40 ° C. and at a relative humidity of 95% or more. The test pieces were fixed on a sample holder and maintained for 240 hours, and the degree of occurrence of blisters was observed.

<Corrosion resistance>

The test was carried out for 240 hours in a salt spray test standard conforming to ASTM D B1117. The cut surface of the test piece was sealed with tape and protected with a cutter on the flat portion. After 240 hours, the degree of occurrence of white rust and blister in the plane portion of the test piece was observed.

<Rubbing property>

First, the IPA solution was applied to the gauze, and a load of 1 kg was applied to the gauze. The surface of the gauze was rubbed up and down 50 times.

Next, using a wet tissue, a load of 2 ~ 2.5 kg was applied, and the surface of the coated film was rubbed 50 times.

<PE Bag property>

The size of the test piece, PE bag and styrofoam was cut to 70x150mm and the load was maintained at 55 ℃ and 95% RH for 12 hours.

[Table 3] below shows the results of the physical property test of the coating film.

 Results of physical property test division Test Methods Property Standard Physical Properties Remarks Film Thickness (㎛) Film thickness meter 5 ~ 7㎛ 6.5 Glossiness Polisher 20 ° / 60 ° 71/127 Pencil hardness Pencil hardness tester F or more F Processability Room temperature, 2T No Crack No Crack C.CT 100/100 100/100 100/100 C.E.T. 6 mm, 100/100 100/100 100/100 Impact ½ inch, 1 kg, 50 cm No Crack No Crack Stain resistance test Meteor Magic (black, blue, red),
30 ° C, 24hrs No abnormality Good UV resistance 15W * 20cm * 24hrs ? E = 1.5 or less 0.18 Chemical resistance 5% Na ₂ CO ₃ Room temperature, 24 hrs No Blister No Blister 5% CH ₃ COOH No Blister Abdominal aquatic 98 ± 2 ° C, 1 hr No abnormality Good Moisture resistance 40 [deg.] C, 95%, 240 hrs No abnormality Good Corrosion resistance 5% NaCl, 240 hrs No Blister Good Rubbing Castle IPA IPA, 1kg, 50 times No abnormality Good wet tissue 2 to 2.5 kg, 50 times Good PE Bag Castle 55 [deg.] C, 95%
2kg weight, 12hrs No abnormality Good

As can be seen from the above test results, the coating film formed by the coating composition according to the present invention showed good results in various properties tests.

Thus, according to the coating composition of the present invention, it is possible to produce a stainless steel coated steel plate for PCM that can satisfy severe processing conditions in the production of a household appliance such as a refrigerator, a washing machine, and a microwave oven.

FIG. 3 is a photograph of a product molded from a refrigerator door using stainless steel coated with a paint according to the present invention.

Further, according to the present invention, it is possible to realize a transparent colored coating layer, and the hair line texture and the metal texture formed on the surface of the stainless steel material can be exposed to the outside by the polishing process.

FIG. 2 is a photograph of a surface of a stainless steel material coated with a paint according to the present invention, which shows that the texture of the hairline is expressed intact.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention.

10: Substrate steel
20: Pre-treatment layer
30: Lower coating layer
40: top coat layer
50: backside layer

Claims (6)

A paint composition for producing a color coated stainless steel coated steel sheet for PCM (Pre-Coated Metal) by coating a stainless steel material and comprising a main resin, a hardener, a pigment, a solvent and an additive ,
Wherein the main resin is an acrylic resin having an OH of 0 to 6.0, a molecular weight (Mn) of 3,000 to 150,000 and a glass transition temperature (Tg) of 50 to 110 ° C in an amount of 15 to 35% &Lt; / RTI &
As the pigment, a colorant containing a pigment dispersed in a nano size is contained in an amount of 1.0 to 7.0% by weight based on the total paint composition,
Hexamethoxymethylmelamine resin having a solid content (NV: Non Volatile) of 98% or more or benzoguanamine having a solid content of 80% or more is contained in an amount of 1.0 to 15.0% by weight based on the total coating composition ,
Wherein the solvent is an aliphatic hydrocarbon-based or ester-based solvent in an amount of 20 to 60% by weight based on the total coating composition. delete delete delete delete A transparent color coated stainless steel coated steel sheet for PCM, which is produced by coating the coating composition of claim 1.

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