KR101111687B1 - Easy Cleaning powder coatings composition - Google Patents

Abstract

The present invention relates to a powder coating composition excellent in fouling resistance, and more particularly, to an existing silicone oil by introducing an isocyanate group curing agent and an acrylic resin into a bifunctional polyester resin having a carboxyl group and a hydroxyl group to increase the crosslinking density of the coating film. The present invention relates to a body paint composition having excellent durability of fouling resistance over time than a powder coating composition imparting fouling resistance by using an additive such as polyethylene or polypropylene waxes.

Pollution resistance, powder coating, bifunctional polyester resin, isocyanate group, acrylic resin

Description

Powder coating composition with excellent stain resistance {Easy Cleaning powder coatings composition}

The present invention relates to a powder coating composition excellent in fouling resistance, and more particularly, to an existing silicone oil by improving the crosslinking density of a coating film by introducing an isocyanate curing agent and an acrylic resin into a bifunctional polyester resin having a carboxyl group and a hydroxyl group. The powder coating composition is more durable than the powder coating composition which gives the stain resistance by using additives such as polyethylene or polypropylene wax, and the efficiency of the coating process is improved due to less pollution to other paints. It is about.

In the past, various materials such as metals, inorganic materials, plastics and woods have been developed for the purpose of protecting products and improving the appearance. In addition, in the case of coatings installed indoors or outdoors, contamination by dust or graffiti becomes a problem, and many paints for improvement have been developed.

In the case of steel sheets used as interior and exterior materials of buildings, the surface is easily contaminated by dust, dust, and organic and inorganic materials, and the exterior is maintained through regular cleaning for continuous management. Thereby, there is a lot of problems to use as an exterior material due to the surface stains, there is also a problem that its function is degraded over time. In addition, when the general paint is used for the interior, when contaminated by a contaminant such as graffiti, dust, etc. by various writing instruments, there is a problem such that the residue of the contaminant remains after cleaning, thereby deteriorating aesthetics. Coatings applied to public transportation such as buses and trains are exposed to many kinds of pollution sources. Contaminated public transportation reduces safety, leading to fewer passengers, reducing revenues and increasing recovery costs for public transportation systems.

In the case of a composition in which an isocyanate curing agent is applied to an existing polyester resin having a hydroxyl group alone to impart fouling resistance, the color of the coating film is changed due to deterioration of storage property and by-products generated by excessive use of the curing agent.

In addition, in case of imparting pollution resistance using additives, problems with persistence have occurred, and in the case of using silicone-based reactive additives to improve such problems, contamination with other paints is caused due to compatibility problems due to additives. You can.

Therefore, to reduce costs, it is necessary to have a product having excellent pollution resistance, sustainability over time, and excellent appearance and storage.

Accordingly, the present inventors have studied to solve the above problems, as a result, by introducing an isocyanate hardener and an acrylic resin into a bifunctional polyester resin having a carboxyl group and a hydroxy group to form a functional coating film imparting non-pollution resistance, corrosion resistance and chemical resistance. The present invention has been completed by improving the contamination problem with other paints and preparing the powder coating composition having excellent storage properties and durability of the paint and excellent appearance.

Accordingly, the present invention relates to 5 to 25 parts by weight of an acrylic resin having a hydroxy group and an epoxy group, 3 to 10 parts by weight of an acrylic resin having an epoxy group, and a curing agent having an isocyanate group with respect to 100 parts by weight of a polyester resin having a carboxyl group and a hydroxyl group. An object of the present invention is to provide a powder coating composition excellent in fouling resistance, containing 0.1 part by weight to 5 parts by weight of a curing accelerator and 50 to 95 parts by weight of a pigment.

The present invention is based on 100 parts by weight of the polyester resin having a carboxyl group and a hydroxyl group, 5 to 25 parts by weight of an acrylic resin having a hydroxy group and an epoxy group, 3 to 10 parts by weight of an acrylic resin having an epoxy group, 10 to 40 parts by weight of a curing agent having an isocyanate group And a powder coating composition excellent in fouling resistance, containing 0.1 to 5 parts by weight of a curing accelerator and 50 to 95 parts by weight of a pigment.

Hereinafter, the present invention will be described in detail.                     

The present invention introduces an isocyanate curing agent and an acrylic resin into a bifunctional polyester resin having a carboxyl group and a hydroxy group to improve crosslinking density of a coating film, thereby preventing contamination by using additives such as silicone oil, polyethylene or polypropylene wax. The present invention relates to a powder coating composition which is more durable in staining with time and less contaminant to other coatings than the powder coating composition to which the coating process is applied.

The composition of each powder coating composition according to the present invention will be described in detail as follows.

The bifunctional polyester resin having a carboxyl group and a hydroxyl group is a resin having excellent mechanical properties and durability. The carboxylic acid value is 5 to 60 mgKOH / g, the hydroxyl value is 5 to 60 mgKOH / g, and the melt viscosity is 2,000 to 5,000. cps (200 ° C.) and a glass transition temperature of 50 ° C. to 70 ° C., for example, fine clad A239X, M8405, M8407 (DAI Corporation), and the like. At this time, when the acid value of the carboxyl group is less than 5 mgKOH / g, the reactivity is poor, mechanical properties such as impact resistance, elongation, flexibility, and weather resistance is lowered, crosslinking density of the coating film is lowered, so that it is easier to penetrate into the coating film of the pollutant, it is contaminated. When it is lowered, when it exceeds 60 mgKOH / g, the reaction rate increases during curing, the appearance is degraded, causing poor storage. In addition, when the acid value of the hydroxyl group is also less than 5 mgKOH / g, there is a problem that the mechanical properties and fouling resistance is lowered, and when the acid value of the hydroxyl group exceeds 60 mgKOH / g, appearance and storage properties are lowered. If the melt viscosity of the polyester resin is less than 2,000 cps (200 ℃) may cause a problem in the curing of the paint, if it exceeds 5,000 cps (200 ℃) there is a problem of appearance degradation. If the glass transition temperature is less than 50 ° C, there is a problem of poor storage properties, and if the glass transition temperature exceeds 70 ° C, the melt dispersibility of the paint is lowered, which is not preferable.

The acrylic resin having a hydroxyl group and an epoxy group has a glass transition temperature of 40 to 80 ° C., an epoxy equivalent of 400 to 700 g / eq, a melt viscosity of 1,000 to 3,000 cps (200 ° C.), and a hydroxyl group acid value of 30 to 70 mgKOH / g. It is preferable to use what is. If the acid value of the hydroxyl group is less than 30 mgKOH / g, the mechanical properties and fouling resistance is lowered, and if it exceeds 70 mgKOH / g, the appearance and storage properties are lowered. In addition, when the epoxy equivalent of the acrylic resin exceeds 700 g / eq crosslinking density may be lowered, fouling resistance and solvent resistance may be lowered, and if the equivalent is less than 400 g / eq, the appearance may be reduced by increasing the reaction rate Can be. If the melt viscosity is less than 1,000 cps (200 ℃) may cause a problem during curing of the paint, if the 3,000 cps (200 ℃) there is a problem that the appearance of the coating is poor. In addition, the preferred content of the acrylic resin having a hydroxy group and an epoxy group is 5 to 25 parts by weight based on 100 parts by weight of the polyester resin, when the content is less than 5 parts by weight there is a problem that the fouling resistance is lowered, 25 weight If the portion is exceeded, there is a problem that the appearance of the coating film becomes poor.

The acrylic resin having an epoxy group preferably has a glass transition temperature of 40 to 60 ° C., an epoxy equivalent of 200 to 500 g / eq, and a melt viscosity of 1,000 to 3,000 cps (200 ° C.). When the epoxy equivalent of the resin is more than 500 g / eq crosslinking density may be reduced to reduce the fouling resistance and solvent resistance, and when the equivalent is less than 200 g / eq may increase the reaction rate may reduce the appearance. If the transition temperature is less than 40 ° C., there is a problem of storage stability, and if it exceeds 60 ° C., there is a problem of bendability, and if the melt viscosity is less than 1,000 cps (200 ° C.), there is a problem of poor appearance and 3,000 cps (200 ° C.). If it exceeds, there is a problem that the pollution resistance is lowered, which is not preferable.

The preferred content of the acrylic resin having the epoxy group is 3 to 10 parts by weight based on 100 parts by weight of the polyester resin, when the content thereof is less than 3 parts by weight, there is a problem that the fouling resistance is lowered, when the content exceeds 10 parts by weight There is a problem of this deterioration.

In this invention, it is preferable that an isocyanate group equivalent is 260-300 g / eq and glass transition temperature is 35-60 degreeC as a hardening | curing agent. If the isocyanate group equivalent is smaller than the above range, there is a problem that the appearance is poor, and if more than the above range, there is a problem that the fouling resistance is lowered. If the glass transition temperature is less than 35 ℃ has a problem of poor storage stability, if it exceeds 60 ℃ there is a problem that the flexibility is reduced. Preferable content of the said hardening | curing agent is 10-40 weight part with respect to 100 weight part of said polyester resins. If the content is less than the above range, the fouling resistance is lowered, but there is a problem that the residue remains after washing with soapy water after standing at room temperature for 24 hours in the state of graffiti with oily magic. And yellowing during baking is undesirable.

The curing accelerator can be selected from dibutyltin dilorate, dibutyltin dilorate impregnated on silica, tinoctoate, dibutyltin diacetate, dibutyltin oxide and tin 2-ethylhexanoate. The preferred amount of the curing accelerator is 0.1 to 5 parts by weight based on 100 parts by weight of the polyester resin, when the content thereof is less than 0.1 parts by weight, there is a problem that the curing of the coating film is poor, if the content exceeds 5 parts by weight the appearance of the coating film There is a problem of this deterioration.

Among the pigments, extender pigments may be aluminum hydroxide, silica, barium sulfate, and the like, and any pigment may be used if it is a conventionally pigmented pigment. Preferably, titanium dioxide, anatase, zinc oxide, etc. Use The preferred content of the pigment is 50 to 95 parts by weight based on 100 parts by weight of the polyester resin, when the content thereof is less than 50 parts by weight, there is a problem that the hiding power is lowered, and when the content exceeds 95 parts by weight, the mechanical properties are deteriorated have.

 As other additives, all additives commonly used in powder coating may be used. Preferably, at least one selected from among ultraviolet absorbers, leveling agents, flow improvers, and pinhole inhibitors may be used in an amount of 1 to 5% by weight. As a flow improver, acrylic type, silicone type, etc. are preferable. If the content of the additive is less than 1% by weight may cause a problem in the appearance of the coating film, if the content of more than 5% by weight there is a problem that the hardness of the coating film falls.

The coating composition as described above is put into a mixing tank, premixed, and melt-dispersed at 70 to 130 ° C. in a disperser to prepare chips. The chip is then crushed with a high-speed mixer and filtered to 100-200 mesh to complete the paint preparation.                     

The powder coating prepared in this way increases the crosslinking density of the coating film, thereby preventing contamination of sources such as dust, dust, acid rain, graffiti caused by various writing instruments, etc. from penetrating into the coating film. Improve chemical resistance.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Examples 1-4 and Comparative Examples 1-4

After mixing the composition as shown in Tables 1 and 2, it was mixed to be uniformly mixed using a container mixer. Next, the uniformly mixed composition was melt mixed at 70 to 130 ° C. through an extruder of an extruder and a kneader (PLK-46, PCM-30, ZSK-25), and then an average particle size was 30 using a grinder. Powder coating with ~ 60 ㎛, particle distribution 10 ~ 100 ㎛, and then cured in 0.7 mm cold rolled steel sheet pretreated with zinc phosphate at 200 ℃ × 10 minutes (based on metal surface temperature), the film thickness of 60 ~ 100 A micrometer coated film specimen was prepared.

Division (g) Example 1 Example 2 Example 3 Example 4 Bifunctional polyester resin Finedic A-329-x ¹⁾ 85 85 70 70 Bifunctional acrylic resin Finedic A-241 ²⁾ 10 15 15 10 Acrylic resin Finedic A-272 ³⁾ 3 3 3 6 Isocyanate Curing Agent B-1530 ⁴⁾ 20 20 20 20 Hardening accelerator BT-71 ⁵⁾ One One One One Other additives Pinhole inhibitor Benzoin ⁶⁾ One One One One Flow improver PV-5 ⁷⁾ One One One One Polyethylene
Wax PE1544 ⁸⁾ One One One One White Pigment CR-80 ⁹⁾ 50 50 50 50 Sieving pigment BaSO ₄ 10 10 10 10 1) Hydroxy Acid Value: 22 mgKOH / g, Carboxylic Acid Value: 14 mgKOH / g, Melt Viscosity 4100cps (200 ℃), Glass Transition Temperature 63 ℃, DIC Corporation
2) Glass transition temperature 66 ℃, epoxy equivalent: 600 g / eq, hydroxyl acid value: 50 mgKOH / g, melt viscosity 2100cps (200 ℃), DIC Corporation
3) Glass transition temperature 51 ℃, Epoxy equivalent: 335 g / eq, Melt viscosity 1750cps (200 ℃), DIC Corporation
4) isocyanate group equivalent 280 g / eq
5) Dibutyltin dilorate, Estron
6) Estrone
7) Warrie Corp
8) Lubrizol
9) Titanium Dioxide, Ishihara

Division (g) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Difunctional ester resin Finedic A-329-x ¹⁾ 85 85 85 80 Bifunctional acrylic resin Finedic A-241 ²⁾ 10 0 10 10 Acrylic resin Finedic A-272 ³⁾ 0 3 3 25 Isocyanate Curing Agent B-1530 ⁴⁾ 20 20 5 20 Hardening accelerator BT-71 ⁵⁾ One One One One Other additives Pinhole inhibitor Benzoin ⁶⁾ One One One One Flow improver PV-5 ⁷⁾ One One One One Polyethylene
Wax PE1544 ⁸⁾ One One One One White Pigment CR-80 ⁹⁾ 50 50 50 50 Sieving pigment BaSO ₄ 10 10 10 10 1) Hydroxy Acid Value: 22 mgKOH / g, Carboxylic Acid Value: 14 mgKOH / g, Melt Viscosity 4100cps (200 ℃), Glass Transition Temperature 63 ℃, DIC Corporation
2) Glass transition temperature 66 ℃, epoxy equivalent: 600 g / eq, hydroxyl acid value: 50 mgKOH / g, melt viscosity 2100cps (200 ℃), DIC Corporation
3) Glass transition temperature 51 ℃, Epoxy equivalent: 335 g / eq, Melt viscosity 1750cps (200 ℃), DIC Corporation
4) isocyanate group equivalent 280 g / eq
5) Dibutyltin dilorate, Estron
6) Estrone
7) Warrie Corp
8) Lubrizol
9) Titanium Dioxide, Ishihara

Test Example

The physical properties of the powder coatings of Examples 1 to 4 and Comparative Examples 1 to 4 were measured as follows, and the results are shown in Tables 3 and 4 below.

[Measurement of physical properties]

1) Leveling: Visual judgment / film smoothness was determined by visual acuity.

2) Gloss: B.W.K Glossmeter / 60 degree reflectance

3) Impact resistance: Measured using an impact tester (DuPont).                     

4) Adhesion: 100 sheaths of 1 mm intervals were attached to the coating film to measure adhesion.

5) Flexibility: Measured using an Eriksen tester.

6) Flexibility: The test was performed using a Gardner Flexibility Tester (B.K.K), 3/16 'bar to check for cracks.

7) Solvent resistance: After 24 hours of immersion in xylene solution, the appearance of gloss deterioration and blistering were observed.

8) Alkali resistance: After 5 hours of aqueous solution of NaOH, the specimens were immersed for 120 hours and then visually observed for the presence of gloss and blisters.

9) Acid resistance: After 5 hours H ₂ SO ₄ aqueous solution, the specimen was immersed for 120 hours and the appearance of gloss, blister, etc. was observed.

10) Boiling water resistance: The appearance was observed after 1 hour infiltration into boiling water.

11) Pollution resistance: After graffiti on the specimen using oily magic, it was left at room temperature for 1 day, washed with soapy water, acetone, xylene, etc., and observed appearance.

division Example 1 Example 2 Example 3 Example 4 Exterior Leveling Good Good Good Good Polish 90 92 91 89 Mechanical properties Impact resistance 1kg / 50cm 1kg / 40cm 1kg / 50cm 1kg / 30cm Adhesion 100/100 100/100 100/100 100/100 flexibility 7 mm 7 mm 7 mm 7 mm Flexibility No cracks No cracks No cracks No cracks Chemical resistance Solvent resistance Good Good Good Good Alkali resistance Good Good Good Good Acid resistance Good Good Good Good Boiling water resistance 1 hour deposition Good Good Good Good Corrosion resistance 1000 hours 1.3 mm 0.4 mm 1.2 mm 0.9 mm Pollution resistance suds No trace No trace No trace No trace Xylene No trace No trace No trace No trace Acetone No trace No trace No trace No trace  Cold Rolled Steel Sheet, 0.7t Zinc Phosphate Coating

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Exterior Leveling Good Good Good Bad Polish 90 92 91 89 Mechanical properties Impact resistance 0.5kg / 20cm 0.5kg / 20cm 0.5kg / 30cm 0.5kg / 40cm Adhesion 100/100 100/100 100/100 100/100 flexibility 3 mm 4 mm 4 mm 4 mm Flexibility Crack Crack Crack Crack Chemical resistance Solvent resistance swelling swelling swelling swelling Alkali resistance Light degradation Light degradation Light degradation Light degradation Acid resistance Good Good Good Good Boiling water resistance 1 hour deposition bubble,
Light degradation bubble,
Light degradation bubble,
Light degradation bubble,
Light degradation Corrosion resistance 1000 hours 1.4 mm 1.2 mm 2.1 mm 2.2 mm Pollution resistance suds Residue generation Residue generation Residue generation No trace Xylene Coating film peeling Coating film peeling Color bleeding Color bleeding Acetone Coating film peeling Coating film peeling Color bleeding Color bleeding  Cold Rolled Steel Sheet, 0.7t Zinc Phosphate Coating

As shown in Table 3 and Table 4, mechanical properties, chemical resistance, boiling water resistance, fouling resistance, corrosion resistance of the powder coating compositions of Examples 1 to 4 are all excellent, while only one acrylic resin was used ( Comparative Examples 1 and 2) When the amount of the acrylic resin and the curing agent is out of the preferred range (Comparative Examples 3 and 4), the mechanical properties, chemical resistance, boiling resistance, contamination resistance and corrosion resistance of the powder coating composition are inferior. have.

As described above, the present invention introduces an isocyanate group curing agent and an acrylic resin into a bifunctional polyester resin having a carboxyl group and a hydroxy group, thereby improving crosslinking density of the coating film, thereby having an excellent effect on fouling resistance, boiling resistance, corrosion resistance, and the like. Powder coating composition can be prepared.

Claims (5)

5 to 25 parts by weight of an acrylic resin having a hydroxy group and an epoxy group, 3 to 10 parts by weight of an acrylic resin having an epoxy group, 10 to 40 parts by weight of an isocyanate curing agent and a curing accelerator of 0.1 to 100 parts by weight of a polyester resin having a carboxyl group and a hydroxyl group. 5 parts by weight, pigments 50 to 95 parts by weight, The acrylic resin having a hydroxyl group and an epoxy group has a glass transition temperature of 40 to 80 ° C., an epoxy equivalent of 400 to 700 g / eq, a melt viscosity of 1,000 to 3,000 cps (200 ° C.), and a hydroxyl group acid value of 30 to 70 mgKOH / g. , The acrylic resin having an epoxy group has a glass transition temperature of 40 to 60 ℃, epoxy equivalent 200 to 500 g / eq, melt viscosity of 1,000 to 3,000 cps (200 ℃) excellent powder coating composition, characterized in that. The bifunctional polyester resin having a carboxyl group and a hydroxyl group has a carboxylic acid value of 5 to 60 mgKOH / g, a hydroxyl group acid value of 5 to 60 mgKOH / g, and a melt viscosity of 2,000 to 5,000 cps (200 ° C.). , Glass transition temperature is 50 ~ 70 ℃ powder coating composition, characterized in that. delete delete The powder coating composition according to claim 1, wherein the curing agent has an isocyanate group equivalent of 260 to 300 g / eq and a glass transition temperature of 35 to 60 ° C.