KR20210081469A - Imprinting pcm coating composition for household appliances and imprinting color sheet using the same - Google Patents

Abstract

The present invention relates to an imprinting pre-coated metal (PCM) coating composition for a home appliance and an imprinting color steel sheet for a home appliance manufactured thereby, and an objective of the present invention is to provide a coating composition capable of clearly and easily implementing an imprinting pattern on a surface of a coating film, and to provide an imprinting color steel sheet capable of maintaining a beautiful color and an outer appearance for a long time without deterioration of basic physical properties even after being used for a long time. To this end, the present invention provides the imprinting PCM coating composition for the home appliance, which is used for performing imprinting on a coating film formed on a base steel sheet by a pattern roll, wherein, based on a total composition, the coating composition includes: 40 to 60 wt% of a fluorine resin; 10 to 20 wt% of a thermoplastic acryl resin; 20 to 30 wt% of a solvent; 5 to 10 wt% of a pigment; and 5 to 10 wt% of an additive, and the fluorine resin is polyvinylidene difluoride (PVDF), which is a thermoplastic crystalline polymer including two or more fluorine atoms among atoms constituting the resin.

Description

Imprinting PCM paint composition for home appliance and imprinting color steel sheet for home appliance manufactured thereby {IMPRINTING PCM COATING COMPOSITION FOR HOUSEHOLD APPLIANCES AND IMPRINTING COLOR SHEET USING THE SAME}

The present invention relates to an imprinting PCM paint composition for home appliance and an imprinting color steel sheet for home appliance manufactured by the same, and more particularly, to an imprinting color steel sheet having a beautiful color and appearance while maintaining physical properties equivalent to that of an existing painting system. It relates to an imprinting PCM paint composition for home appliances that can be easily manufactured and the imprinted color steel sheet can maintain a beautiful appearance for a long time, and an imprinting color steel sheet for home appliances manufactured thereby.

In the coating method of the steel sheet, there are a post-coating method in which the steel sheet is formed and then coated, and a pre-coating method in which the steel sheet is coated before forming and processing.

The post-coating method has a disadvantage in that it is difficult to produce uniform products and mass production, although the equipment cost is low and it is advantageous for small-volume production.

On the other hand, the pre-coating method has advantages in that a uniform product can be produced, loss of paint is small, and mass production is possible within a short time.

A steel sheet coated with the above pre-coating method is usually referred to as a PCM (Pre-Coated Metal) steel sheet, and a paint used for pre-coating is referred to as a PCM paint.

Meanwhile, fluororesin is mainly used as a PCM paint for color steel sheets used as interior/exterior materials for home appliances or construction.

The fluororesin is a synthetic polymer containing fluorine in the carbon main chain constituting the resin, and has advantages in heat resistance, electrical insulation, and chemical resistance.

The paint to which the fluororesin is applied has been widely used as an interior/exterior material for home appliances or construction because it is thermally and chemically very stable and has excellent weather resistance, durability, and chemical resistance.

Recently, the fluororesin has been applied to topcoat paints for steel sheets used in highly corrosive environments, such as automobiles, communications, semiconductors, chemical plants, vehicles, and bridges, in addition to PCM paints.

Among them, the fluorine color steel sheet used for home appliances forms various patterns on the surface of the steel sheet by applying physical pressure to the panel itself.

On the other hand, there is an imprinting method among methods of forming a pattern pattern having irregularities on the coating layer of the steel sheet.

1 schematically shows a process of forming a pattern on the surface of a steel sheet by such an imprinting method.

In the above-described imprinting method, as shown in FIG. 1 , a paint is applied to the base steel sheet and passed through an oven 100 , and then a pattern roll 60 is pressed to form a certain pattern on the surface of the steel sheet. After forming, the imprinting color steel sheet is manufactured by passing it through the quenching device 200 .

However, when imprinting on a conventional fluorine paint film, it is difficult to implement a texture of a clear pattern due to the crystallization characteristics of fluorine, and there is a problem that the imprinted pattern is restored again.

Domestic Patent Publication No. 10-2018-0119188 (published on November 2, 2018) Domestic Registered Patent No. 10-1459359 (Registered on November 3, 2014) Domestic Registered Patent No. 10-14321750 (Registered on August 13, 2014)

The present invention is to solve the problems of the prior art, and provides an imprinting PCM paint composition for home appliances that can clearly and easily implement an imprinting pattern on the surface of a coating film while using the advantages of fluorine resin as it is but it has a purpose.

Another object of the present invention is to provide an imprinting PCM paint composition for home appliances capable of producing a color steel sheet having excellent color and appearance as well as excellent basic physical properties such as weather resistance and corrosion resistance.

Another object of the present invention is to manufacture an imprinting color steel sheet for home appliances that can maintain a beautiful color and appearance for a long time without deterioration in basic physical properties even after long-term use.

In order to achieve the above object, the present invention provides an imprinting PCM paint composition for home appliances used for imprinting a coating film formed on a base steel sheet by a pattern roll, wherein the paint composition is a fluororesin based on the entire composition. 40 to 60% by weight, 10 to 20% by weight of a thermoplastic acrylic resin, 20 to 30% by weight of a solvent, 5 to 10% by weight of a pigment, 5 to 10% by weight of an additive, the fluororesin contains the resin It is characterized in that it is polyvinylidene difluoride (PVDF), which is a thermoplastic, crystalline polymer containing two or more fluorine atoms among constituent atoms.

In addition, the fluororesin has a weight average molecular weight of 200,000 to 400,000, a melting point of 140 to 180° C., a specific gravity of 1.7 to 1.8, and a solid content of 20 to 70% by weight.

In addition, the thermoplastic acrylic resin has a glass transition temperature (Tg) of 60°C, a weight average molecular weight (Mw) of 80,000 to 100,000, a non-volatile (N/V) of 25%, a viscosity of 0.4, and an acid value of 2 It is characterized by the following.

In addition, the pigment is used by mixing an organic pigment and a metallic pigment, and the metallic pigment is characterized in that it contains an aluminum silicate component.

In addition, the solvent includes an isophorone component, and the isophorone is characterized in that it is contained in an amount of 50 to 80% by weight based on the solvent.

In addition, the additive includes an interlayer adhesive, and the interlayer adhesive includes a polysiloxane copolymer and a low molecular weight unsaturated polycarboxylic acid polymer.

And the imprinting color steel sheet according to the present invention is composed of a base steel sheet 10, a pretreatment layer 20, a primer layer 30, a base layer 40 and a clear layer 50, and the primer layer 30 A paint containing a polyester-based resin containing a rust preventive pigment is applied, and the coating composition according to the present invention is applied to the base layer 40 and the clear layer 50 .

According to the present invention, there is an effect that the imprinting pattern can be clearly and easily implemented on the surface of the coating film while using the advantages of the fluororesin as it is.

In addition, it has the effect of manufacturing color steel sheets with excellent color and appearance as well as excellent basic physical properties such as weather resistance and corrosion resistance.

In addition, even if the color steel sheet is used for a long period of time, the basic properties are not deteriorated and the beautiful color and appearance can be maintained for a long time.

1 is a view schematically showing a process of manufacturing a color steel sheet by an imprinting process;
2 is a schematic cross-sectional view of an imprinting color steel sheet according to the present invention.
3 is an enlarged photograph of the imprinting pattern of the color steel sheet manufactured according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The imprinting PCM paint composition for home appliances according to the present invention is a paint applied to a base layer and a clear layer of a color steel sheet for imprinting on a dry film with a pattern roll, and the paint composition is a fluororesin based on the entire composition. 40 to 60% by weight, 10 to 20% by weight of a thermoplastic acrylic resin, 20 to 30% by weight of a solvent, 5 to 10% by weight of a pigment, and 5 to 10% by weight of additives.

The present inventors tried to prepare a paint composition in which an acrylic resin was added to an existing fluororesin paint to improve pigment dispersion and adhesion, and to use it in an imprinting process.

However, a clear pattern could not be obtained by grafting a conventional acrylic resin to the existing fluororesin paint.

The reason was analyzed to be because the fluororesin is a non-reactive, non-crosslinkable resin, and the glass transition temperature of the conventional acrylic resin itself is high, and thus the time to remain in the free state during heating is short.

Accordingly, the present inventors were able to solve the above problem by grafting a thermoplastic acrylic resin having a low glass transition temperature and flexible bonding strength to polyvinylidene difluoride (PVDF) as a fluororesin.

According to the present invention, the imprinting PCM paint coating material satisfies the same workability and the same physical properties as compared to the existing fluororesin paint, and the imprinting pattern can be clearly and easily implemented in the imprinting process compared to the existing fluororesin paint. could have

Hereinafter, each component of the paint composition for imprinting PCM according to the present invention will be described.

<Fluorine resin>

As a fluororesin used in the coating composition of the present invention, polyvinylidene difluoride (hereinafter 'PVDF'), which is a thermoplastic and crystalline polymer containing two or more fluorine atoms among atoms constituting the resin, is ') is used.

The PVDF is prepared by polymerization of vinylidene difluoride, and is preferably contained in an amount of 40 to 60 wt % based on the total coating composition.

When the content of the PVDF is less than 40% by weight, workability in the imprinting process is reduced, and problems occur in the appearance of the coating film, workability, and pattern implementation.

On the other hand, when the content of PVDF exceeds 60% by weight, the imprinting pattern implementation becomes easy, but the pigment content is reduced, so that it is difficult to implement color, and weather resistance and adhesion are also reduced.

And it is preferable that the PVDF has a weight average molecular weight of 200,000 to 400,000, a melting point of 140 to 180° C., a specific gravity of 1.7 to 1.8, and a solid content (based on the coating composition) of 20 to 70% by weight.

The above-described physical properties are a range in which a clear imprinting pattern can be realized, which the present inventors have discovered through numerous imprinting experiments.

<Thermoplastic acrylic resin>

As the acrylic resin according to the present invention, a solid thermoplastic acrylic resin provided in the form of pellets is used.

The thermoplastic acrylic resin is preferably contained in an amount of 10 to 20% by weight based on the total composition.

When the content of the thermoplastic acrylic resin is less than 10% by weight, the flexibility of the coating film is lowered, so that the pattern is not well realized, and when it exceeds 20%, the clarity of the pattern is deteriorated.

In addition, the thermoplastic acrylic resin has a glass transition temperature (Tg) of 60°C, a weight average molecular weight (Mw) of 80,000 to 100,000, a non-volatile (N/V) of 25%, a viscosity of 0.4, and an acid value of 2 It is preferable that it is below.

The above-described physical property values are optimal values for clearly realizing the imprinting pattern.

The thermoplastic acrylic resin has excellent weather resistance and hardness, has flexibility, is easily soluble in organic solvents such as ketones and esters, and is well compatible with cellulose, epoxy resin, vinyl resin, and the like.

In particular, when mixed with PVDF, stability can be improved, and drying properties and color diffusivity can be improved.

The present inventors paid attention to this point, and by mixing PVDF with a thermoplastic acrylic resin having a low glass transition temperature and flexible bonding strength, the imprinting pattern could be clearly and easily implemented.

<solvent>

The solvent serves to lower the viscosity by diluting it appropriately for painting when the paint has no fluidity at room temperature or it is difficult to paint due to its high viscosity.

The solvent of the present invention is preferably contained in an amount of 20 to 30% by weight based on the total composition.

In addition, the solvent includes an isophorone component, and the isophorone is preferably contained in an amount of 50 to 80% by weight based on the solvent.

When the content of isophorone in the solvent component is less than 50% by weight, the dissolving power for the fluororesin is lowered, and when it exceeds 80% by weight, there is a problem in that imprinting workability is reduced.

<Pigment>

Pigments play a role in realizing color and providing hiding power in the paint.

The pigment of the present invention is made by mixing an organic pigment and a metallic pigment.

In addition, the metallic pigment preferably includes an aluminum silicate component for the purpose of improving scratch resistance and coating film hardness.

The pigment is preferably contained in an amount of 5 to 10% by weight based on the total composition.

<Additives>

Additives are used to improve the physical properties of paints, and although their blending amount is small, they play a very important role in paints.

In the present invention, an interlayer adhesive is added to improve interlayer adhesion, and the interlayer adhesive preferably includes a polysiloxane copolymer and a low molecular weight unsaturated polycarboxylic acid polymer.

The interlayer adhesive is preferably contained in an amount of 0.5 to 2.0% by weight based on the total composition of the additive.

When the content of the interlayer adhesive is less than 0.5% by weight, the interlayer adhesion effect is insignificant, and when it exceeds 2.0% by weight, there is a problem in that the storage stability is reduced by inducing seeding.

In addition, additives such as a leveling agent, a dispersing agent, an antifoaming agent, and a thixotropic agent may be additionally added.

On the other hand, the imprinting color steel sheet for home appliances according to the present invention, as shown in FIG. 2 , a base steel sheet 10 , a pretreatment layer 20 , a primer layer 30 , a base layer 40 and a clear layer 50 . is composed of

Here, the primer layer 30 is coated with a paint containing a polyester-based resin containing a rust preventive pigment, and the paint according to the present invention is applied to the base layer 40 and the clear layer 50 .

And the primer layer 30 is formed in the range of PMT (Peak Metal Temperature) 200 ~ 220 ℃ in the continuous PCM line, the dry film thickness is preferably 3 ~ 10㎛, it is 4 ~ 6㎛ more preferably.

This is because when the dry coating film thickness of the primer layer 30 is less than 3 μm, rust prevention and adhesion are reduced, and when it exceeds 10 μm, the appearance of the surface becomes poor and it is uneconomical.

In addition, it is preferable to apply a non-toxic rust preventive pigment to the paint forming the primer layer 30 .

3 is an enlarged photograph of the imprinting pattern of the color steel sheet manufactured according to the present invention, and it can be seen that the imprinting pattern is clearly implemented in the dry coating film.

Hereinafter, the test results of the color steel sheet manufactured using the coating composition according to the present invention will be described.

First, the specimen specifications and coating conditions used in the test of the present invention are as follows.

A test steel sheet was prepared so that the dry coating film thickness was 5 μm for the primer layer 30, 15 μm for the PVDF base layer 40, and 15 μm for the PVDF clear layer 50 on a non-chromium 0.45T GI (hot-dip galvanized steel sheet). .

Then, the primer layer 30 was baked at 216° C., the base layer 40 at 241° C., and the clear layer 50 at 241° C.

[Table 1] below shows the composition of the paint used to form the base layer 40 and the clear layer 50.

Composition of the paint applied to the specimen (wt%) ingredient comparative example Example 1 Example 2 Example 3 Example 4 Example 5 PVDF
(KYNAR 500) 35.91 40.81 25.65 30.78 35.91 40.81 acrylic resin
(A resin)
15.39
10.5
-
-
-
- thermoplastic
acrylic resin
(B resin)
-
-
25.65
20.52
15.39
10.5 solvent 25.8 25.8 25.8 25.8 25.8 25.8 leveling agent 0.5 0.5 0.5 0.5 0.5 0.5 adhesion promoter 1.6 1.6 1.6 1.6 1.6 1.6 dispersant 0.5 0.5 0.5 0.5 0.5 0.5 inorganic pigment 8 8 8 8 8 8 metallic pigment 0.6 0.6 0.6 0.6 0.6 0.6 antifoam One One One One One One thixotropic agent 0.1 0.1 0.1 0.1 0.1 0.1

Here, in Comparative Examples and Example 1, PVDF according to the present invention and a conventional acrylic resin (resin A) were used, and in Examples 2 to 5, PVDF and a thermoplastic acrylic resin (resin B) according to the present invention were used.

The thermoplastic acrylic resin (resin B) according to the present invention has a glass transition temperature (Tg) of 60°C, a weight average molecular weight (Mw) of 100,000, a non-volatile (N/V) of 25%, a viscosity of 0.4, and an acid value (Acid). value) of 2 was used.

Then, the following physical property test was performed on the above specimen.

<Pencil hardness>

The results of the limit values to withstand scratching were observed using "Uni Pencil" manufactured by Mitsubishi, Japan.

<C.E.T>

A cross cut was made at intervals of 1 mm to make 100 graduations, and a taping peel test was performed after extruding 6 mm.

<Impact test>

After the impact weight was dropped under the conditions of 1/2 inch in diameter, 0.5 kg of drop load, and 50 cm in height, the presence of cracks in the deformed part was checked.

<Gloss>

The glossiness of 60 degrees was measured with a gloss meter.

<Boiling water resistance>

After immersion in boiling water of 98°C or higher for 1 hour, the state of the coating film was evaluated.

<Processability>

After processing with a vise at room temperature, the occurrence of cracks in the processing area was evaluated.

<Chemical resistance>

5% HCL and 5% NaOH solution was dropped on the coating film, a cap was placed on it and left at 20 degrees for 72 hours, and then washed with water to evaluate the appearance of the coating film.

<Corrosion resistance>

Salt spray test was performed at 35°C, and after immersion in 5% NaCl and 1000 hours, the occurrence of blisters in the flat part and the X-cut part was evaluated.

<weather resistance>

The blister of the X-cut part was evaluated.

<weather resistance>

After standing for 3000 hours in QUV-A, the appearance, discoloration and chalking were evaluated.

<Imprinting pattern implementation>

Imprinting patterns were formed by pressing with a pattern roll immediately after topcoating, and then the appearance was evaluated.

[Table 2] below shows the results of the physical property comparison test.

Physical property comparison test result Item Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 pencil hardness F F H H F F C.E.T. 100/100 100/100 100/100 100/100 100/100 100/100 impact test Good Good Good Good Good Good Polish 30 25 75 75 70 70 boiling water resistance Good Good Good Good Good Good machinability 0T N/C 0T N/C 1T N/C 1T N/C 0T N/C 0T N/C chemical resistance Good Good Good Good Good Good corrosion resistance Good Good Good Good Good Good weather resistance Good Good Good Good Good Good fire resistance Good Good Good Good Good Good imprinting
pattern implementation usually usually usually usually Good Great

As can be seen from the above comparative test results, Comparative Example 1 and Example 1 using PVDF and the conventional acrylic resin (resin A) had almost no difference in physical properties and imprinting pattern implementation.

However, in Examples 2 to 5 using PVDF and a thermoplastic acrylic resin (resin B), as the content of PVDF increases and the content of the thermoplastic acrylic resin (resin B) decreases, the imprinting pattern implementation is excellent while maintaining the same level of physical properties it can be seen that

In particular, in the case of Example 5, it was found that the imprinting pattern implementation was the best.

However, it was found that as the content of PVDF increased and the content of the thermoplastic acrylic resin (resin B) decreased, the glossiness decreased slightly.

According to the present invention, by using PVDF as a basic paint, even when used for a long time in an external environment, the color of the coating film of the base layer and the clear layer does not discolor or deteriorate, and stable physical properties can be exhibited.

In addition, by using a thermoplastic acrylic resin (resin B) together with PVDF, the imprinting pattern can be clearly and easily implemented.

In the above, preferred embodiments of the present invention have been exemplarily described, and the scope of the present invention is not limited to the specific embodiments described above. Those of ordinary skill in the art will understand that various changes and modifications are possible without departing from the scope of the technical spirit of the present invention.

10: Soji steel plate
20: pretreatment layer
30: Primer layer
40: base (Base) layer
50: clear layer
60: pattern roll (Pattern Roll)
100: Oven
200: quencher

Claims (9)

In the imprinting PCM paint composition for home appliances used for imprinting by a pattern roll on a coating film formed on a base steel plate,
The paint composition is
Based on the total composition, 40 to 60% by weight of fluororesin, 10 to 20% by weight of thermoplastic acrylic resin, 20 to 30% by weight of solvent, 5 to 10% by weight of pigment, and 5 to 10% by weight of additives. ,
The fluororesin is
An imprinting PCM paint composition for home appliances, characterized in that it is polyvinylidene difluoride (PVDF), a thermoplastic, crystalline polymer containing two or more fluorine atoms in the atoms constituting the resin. The method of claim 1,
The fluororesin is
Imprinting PCM paint composition for home appliance, characterized in that it has a weight average molecular weight of 200,000 to 400,000, a melting point of 140 to 180° C., a specific gravity of 1.7 to 1.8, and a solid content of 20 to 70% by weight. The method of claim 1,
The thermoplastic acrylic resin has a glass transition temperature (Tg) of 60°C, a weight average molecular weight (Mw) of 80,000 to 100,000, a non-volatile (N/V) of 25%, a viscosity of 0.4, and an acid value of 2 or less. Imprinting PCM paint composition for home appliances, characterized in that The method of claim 1,
The pigment is used by mixing an organic pigment and a metallic pigment,
The metallic pigment is an imprinting PCM paint composition for home appliances, characterized in that it comprises an aluminum silicate component. The method of claim 1,
The solvent contains an isophorone component,
The imprinting PCM paint composition for home appliances, characterized in that the isophorone is contained in an amount of 50 to 80% by weight based on the solvent. The method of claim 1,
The additive includes an interlayer adhesive,
The interlayer adhesive is an imprinting PCM paint composition for home appliances, characterized in that it comprises a polysiloxane copolymer and a low molecular weight unsaturated polycarboxylic acid polymer. An imprinting color steel sheet for home appliances, characterized in that it is manufactured using the coating composition according to any one of claims 1 to 6. 8. The method of claim 7,
The imprinting color steel sheet,
Consists of a base steel plate 10, a pretreatment layer 20, a primer layer 30, a base layer 40 and a clear layer 50,
A paint containing a polyester-based resin containing a rust preventive pigment is applied to the primer layer 30,
An imprinting color steel sheet for home appliances, characterized in that the coating composition according to any one of claims 1 to 6 is applied to the base layer (40) and the clear layer (50). 9. The method of claim 8,
The primer layer 30 is formed in the range of PMT (peak metal temperature) 200 ~ 220 ℃ in the continuous PCM line, and the dry film thickness of the imprinting color steel sheet for home appliance, characterized in that 3 ~ 10㎛.

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