KR102602456B1 - Polyester Paint Composition for PCM - Google Patents

Abstract

The present invention provides a polyester paint composition for PCM containing a polyester resin having a number average molecular weight of 1,000 to 5,000, a hydroxyl value of 20 to 150 mgKOH/g, and a glass transition temperature of 20 to 30°C.

Description

Polyester paint composition for PCM {Polyester Paint Composition for PCM}

The present invention relates to a polyester paint composition for PCM, and more specifically, to a polyester paint composition for PCM with ultra-high weather resistance that exhibits excellent weather resistance even in high temperature and high humidity areas.

Pre-Coated Metal (PCM) paint compositions require excellent weather resistance, corrosion resistance, scratch resistance, gloss, hardness, and flexibility, and are used for exterior building materials and home appliances. It is applied in various ways. In general, binder resins used in PCM paint compositions are diverse, including polyester-based, acrylic-based, urethane-based, epoxy-based, silicone-based, fluorine-based, and polyvinyl chloride-based. Most of the PCM paint compositions are thermosetting, and PCM paint compositions using polyester resins are most commonly used except for products requiring special physical properties.

Conventional polyester paint compositions for PCM had the problem of poor weather resistance, such as chalking, often occurring in areas with strong ultraviolet rays and high temperatures and humidity.

One object of the present invention is to provide an ultra-high weather resistance polyester paint composition for PCM that can exhibit excellent gloss retention, color retention, and chalking resistance even when exposed to a climate environment with strong ultraviolet rays and high temperature and humidity for a long period of time.

On the other hand, the present invention provides a polyester paint composition for PCM containing a polyester resin with a number average molecular weight of 1,800 to 2,200, a hydroxyl value of 65 to 75 mgKOH/g, and a glass transition temperature of 20 to 30°C.

In one embodiment of the present invention, the polyester paint composition for PCM is a polyester resin 30 to 40 having a number average molecular weight of 1,800 to 2,200, a hydroxyl value of 65 to 75 mgKOH/g, and a glass transition temperature of 20 to 30°C. weight%; 40 to 50% by weight of coloring agent; 5 to 10% by weight of hardener; 0.1 to 3% by weight of acid catalyst; 1 to 5% by weight of matting agent; and 3 to 20% by weight of solvent.

On the other hand, the present invention provides a coating film formed using the polyester coating composition for PCM.

On the other hand, the present invention provides a PCM steel sheet coated with a coating film formed using the polyester paint composition for PCM.

The polyester paint composition for PCM according to the present invention can form an ultra-high weather resistance coating film that can exhibit excellent gloss retention, color retention, and chalking resistance even when exposed to a climate environment with strong ultraviolet rays and high temperature and humidity for a long period of time.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention relates to a polyester paint composition for PCM containing a polyester resin having a number average molecular weight of 1,800 to 2,200, a hydroxyl value of 65 to 75 mgKOH/g, and a glass transition temperature of 20 to 30°C.

In one embodiment of the present invention, as described above, the polyester resin has a number average molecular weight of 1,800 to 2,200, a hydroxyl value of 65 to 75 mgKOH/g, and a glass transition temperature of 20 to 30°C. If the number average molecular weight, hydroxyl value, and glass transition temperature of the polyester resin are outside the above range, gloss retention, color retention, and chalking resistance may decrease when exposed to strong ultraviolet rays and high temperature and humidity conditions for a long period of time.

A polyester paint composition for PCM according to an embodiment of the present invention includes 30 to 40% by weight of the polyester resin; 40 to 50% by weight of coloring agent; 5 to 10% by weight of hardener; 0.1 to 3% by weight of acid catalyst; 1 to 5% by weight of matting agent; and 3 to 20% by weight of solvent.

In one embodiment of the present invention, the polyester resin may be used in an amount of 30 to 40% by weight based on the total 100% by weight of the polyester paint composition. If the polyester resin is included in less than 30% by weight, there may be disadvantages such as reduced processability, and if it is included in more than 40% by weight, there may be disadvantages such as reduced hiding power.

In one embodiment of the present invention, the coloring agent is a component that imparts hiding power and/or coloring power to the paint film. As the colorant, those commonly used in polyester paint compositions for PCM can be used without limitation. Specifically, the coloring agent may be a pigment containing titanium oxide white, cyanine blue, iron oxide red, carbon black, chrome yellow, etc. The content of pigment in the colorant may be 30 to 70% by weight based on 100% by weight of the colorant. The coloring agent can be used alone or in combination to adjust the color of the paint film.

The colorant can be used in the range of 40 to 50% by weight based on the total 100% by weight of the polyester paint composition for PCM. If the content of the colorant is less than 40% by weight, there may be a problem of poor concealment, and if the content of the colorant is more than 50% by weight, there may be problems of reduced coating film properties and increased costs.

In one embodiment of the present invention, the curing agent serves to cure the polyester resin to form a stable coating film.

The curing agent generally used in polyester resin can be used without limitation. Specifically, melamine resin, etc. may be used as the curing agent.

The melamine resin may be methoxy melamine resin, or methoxy/butoxy mixed melamine resin. The methoxy melamine resin can be obtained by polymerizing methanol and formaldehyde, and the methoxy/butoxy mixed melamine resin can be obtained by polymerizing a mixture of methanol, iso-butanol, or normal-butanol, and formaldehyde. The molecular weight of the melamine resin may be 300 to 1,000.

Examples of commercially available products of the methoxy melamine resin include MR603 (CHANG CHUN PLASTIC), CYMEL-303, CYMEL-325, CYMEL-327, CYMEL-350, CYMEL-370 (CYTEC), RESIMINE-7550, RESIMINE-717. , RESIMINE-730, RESIMINE-747, RESIMINE-797 (SOLUTIA), BE-3717, BE-370, BE-3747 (BIP), etc. Examples of commercially available products of methoxy/butoxy mixed melamine resin include There are RESIMINE-755, RESIMINE-757, RESIMINE-751 (SOLUTIA), CYMEL-1168, CYMEL-1170, CYMEL-232 (CYTEC).

The curing agent may be used in an amount of 5 to 10% by weight based on 100% by weight of the polyester paint composition for PCM. If the content of the curing agent is less than 5% by weight, contamination resistance and solvent resistance may be reduced, and if the content of the curing agent is more than 10% by weight, the flexibility and impact resistance of the coating film may be reduced.

In one embodiment of the present invention, the acid catalyst serves to improve the density of the coating film by promoting curing of the polyester resin and the curing agent.

As the acid catalyst, p -toluenesulfonic acid, epoxy-shielded dinonylnaphthalenesulfonic acid (DNNSA), or dodecylbenzenesulfonic acid (DDBSA) can be used, and these can be used alone or in combination of two or more.

The acid catalyst may be included in an amount of 0.1 to 3% by weight based on 100% by weight of the total polyester paint composition for PCM. If the acid catalyst is included in less than 0.1% by weight, there may be a disadvantage in that the coating film is not cured, and if it is included in more than 3% by weight, there may be disadvantages such as deterioration in processability.

In one embodiment of the present invention, the matting agent serves to lower the gloss of the coating film, and any commonly used polyester paint composition for PCM can be used without limitation. Specifically, synthetic silica, etc. may be used as the matting agent.

The matting agent may be included in an amount of 1 to 5% by weight based on 100% by weight of the total polyester paint composition for PCM. If the matting agent is included in less than 1% by weight, the effect of lowering the gloss of the coating film may be minimal, and if it is included in more than 5% by weight, stain resistance may be reduced.

In one embodiment of the present invention, various organic solvents capable of dissolving polyester resin can be used as the solvent, for example, Cocosol #100 (Kocosol #100, K-100, SK Energy Co., Ltd.), Cocosol #150 (Kocosol #150, K-150, SK Energy Co., Ltd.), cyclohexanone, xylene, cellosolve acetate, toluene, methyl ethyl ketone, dibasic ester, or a mixed solvent thereof can be used.

The solvent may be included in an amount of 3 to 20% by weight based on 100% by weight of the total polyester paint composition for PCM. If the solvent is included in less than 3% by weight, the adhesion of the coating film may decrease, and if it is included in more than 20% by weight, drying may take a long time.

The polyester paint composition for PCM according to an embodiment of the present invention may further include various additives such as anti-settling agents, light stabilizers, and curing aids, as needed.

In one embodiment of the present invention, the anti-settling agent is a component that complements the storage stability of the paint and improves workability and film properties. As the anti-settling agent, those commonly used in polyester paint compositions for PCM can be used without limitation. Specifically, silica, clay, etc. may be used as the anti-settling agent. The anti-settling agent can be used alone or in combination to control the physical properties of the coating film.

The light stabilizer may be a conventional light stabilizer, for example, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate.

The curing aid may be used to promote curing of the surface of the coating film, for example, triethylamine, etc. may be used.

One embodiment of the present invention relates to a coating film formed using the polyester coating composition for PCM.

The polyester paint composition for PCM according to the present invention can be applied to a metal plate using methods such as bar coating, curtain coating, roll coating, dip coating, and spray coating, and then dried to form a coating film.

At this time, the coating film thickness may be 5 to 25 ㎛, and baking may be performed for 35 to 40 seconds under conditions of, for example, 250 to 280°C.

The metal plate may be cold-rolled steel (CR), zinc hot-dipped steel (GI), electro-galvanized steel (EGI), alloy-plate steel (GA), copper sheet, or tin-plate steel.

Additionally, the metal plate may be pretreated with phosphate or chromate before painting. Additionally, for adhesion of the coating film, an epoxy type primer, a polyester type primer, an acrylic type primer, or a modified version thereof may be used as an undercoat.

Additionally, one embodiment of the present invention relates to a PCM steel sheet coated with a coating film formed using the polyester paint composition for PCM.

Hereinafter, the present invention will be described in more detail through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are only for illustrating the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

Example 1 to 5 and Comparative example 1 to 2: For PCM Preparation of polyester paint composition

A polyester paint composition for PCM was prepared with the composition shown in Table 1 below (unit: parts by weight).

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative example 2 Polyester resin 1 ^{1 )} 300 300 Polyester resin 2 ^{2 )} 300 300 300 Polyester resin 3 ^{3 )} 300 Polyester resin 4 ^{4 )} 300 MR603 ^{5 )} 50 75 75 75 75 50 50 AEROSIL 200 solution ^{6 )} 40 40 40 40 40 40 40 Triethylamine (TEA) solution ^{7 )} 5 5 5 TINUVIN 292 ⁸⁾ 5 5 5 5 BLACK TINTER ⁹⁾ 238 238 238 238 238 238 238 YELLOW TINTER ¹⁰⁾ 30 30 30 30 30 30 30 White coloring agent (WHITE TINTER) ¹¹⁾ 99 99 99 99 99 99 99 RED TINTER ¹²⁾ 35 35 35 35 35 35 35 Matting agent ^{13 )} 20 20 20 20 20 20 20 NACURE 2501 ¹⁴⁾ 5 5 5 B-CAT 0053 ¹⁵⁾ 8 8 8 8 8 8 CATA CFC-5019KC ^{16 )} 4 4 4 4 4 4 Kocosol #150 20 20 20 20 20 20 20 Cyclohexanone 30 30 30 30 30 30 30

1) Polyester resin (KCC), NV: 70%, Mn: 2,000, glass transition temperature: 24℃, hydroxyl value: 70

2) Polyester resin (KCC) NV: 68%, Mn: 2,200, glass transition temperature: 30℃, hydroxyl value: 75

3) Polyester resin (KCC), NV: 65%, Mn: 6,500, glass transition temperature: 15℃, hydroxyl value: 35

4) Polyester resin (KCC) NV: 63%, Mn: 1,600, glass transition temperature: 18℃, hydroxyl value: 80

5) Methoxy melamine resin (CHANG CHUN PLASTIC CO., LTD.), molecular weight: 1000 or less, NV: 98%

6) Fumed silica solution (GRACE)

7) Triethylamine solution (TAMINCO N.V.)

8) Bis(1-octyloxy-2,2,6-tetramethyl-4-piperidyl)sebacate (BASF)

9) Black coloring agent (KCC company, pigment content 35% by weight)

10) Yellow coloring agent (KCC company, pigment content 54% by weight)

11) White colorant (KCC company, pigment content 65% by weight)

12) Red coloring agent (KCC company, pigment content 54% by weight)

13) Synthetic silica (Schemtech)

14) p-TSA (KING INDUSTRIES)

15) Epoxy shielded DNNSA (FTC KOREA)

16) DDBSA (Cheongwoosa Temple)

Experiment example : Evaluation of coating film properties

The coating composition prepared in the above examples and comparative examples was applied to a steel sheet as a bar, and then baked at a temperature of 280°C for 30 seconds to prepare a steel sheet coated with a 20 ㎛ thick coating film.

The physical properties of the coating film were evaluated using WOM ASTM D7869-13, WOM ASTM D6695-08, and QUV-A EN 13523-10 evaluation methods, respectively, and the results are shown in Table 2 below. The evaluation items were gloss retention, color difference, and chalking.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative example 2 W-O-M ASTM D7869-13 1000 hours Gloss retention rate 38.3% 36.5% 24.8% 34.3% 42.4% 15.0% 18% color difference 0.32 0.71 0.45 0.65 0.46 1.17 1.2 Chalking 10 10 10 10 10 10 10 2000 hours Gloss retention rate 26.3% 16.4% 15.4% 15.9% 23.4% 3.6% 4.5% color difference 0.69 1.03 1.43 1.01 0.73 5.29 6.21 Chalking 10 10 10 10 10 6 5 W-O-M ASTM D6695-08 3000 hours Gloss retention rate 70.5% 74.8% 54.6% 66.1% 75.8% 53.3% 52.5% color difference 0.35 0.33 0.72 0.46 0.34 0.97 0.99 Chalking 10 10 10 10 10 8 7 5000 hours Gloss retention rate 56.2% 64.9% 34.8% 52.6% 67.9% 12.8% 14.8% color difference 0.41 0.42 0.89 0.46 0.36 0.83 0.85 Chalking 10 10 10 10 10 10 10 QUV-A EN 13523-10 3000 hours Gloss retention rate 78.1% 84.0% 66.9% 81.3% 89.1% 77.2% 76% color difference 0.4 0.32 1.18 0.42 0.4 1.62 1.82 Chalking 10 10 10 10 10 10 10 5000 hours Gloss retention rate 77.2% 87.4% 62.3% 77.4% 90.4% 10.8% 12.5% color difference 1.81 1.59 3.08 2.38 1.6 4.2 5.2 Chalking 10 10 10 10 10 8 8

As can be seen from the results in Table 2, the coating film formed from the polyester paint composition for PCM containing the polyester resin of Examples 1 to 5 has a number average molecular weight, hydroxyl value, and glass transition temperature outside the above range. It was found that compared to the coating film formed from the polyester paint composition for PCM of Examples 1 and 2, it can exhibit better gloss retention, color retention, and chalking resistance even when exposed to strong ultraviolet rays and a high temperature and high humidity environment for a long period of time.

As the specific parts of the present invention have been described in detail above, it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. do. Anyone skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (4)

30 to 40% by weight of a polyester resin having a number average molecular weight of 2,000 to 2,200 g/mol, a hydroxyl value of 70 to 75 mgKOH/g, and a glass transition temperature of 24 to 30°C;
40 to 50% by weight of coloring agent;
5 to 10% by weight of hardener;
0.1 to 3% by weight of acid catalyst;
1 to 5% by weight of matting agent; and
A polyester paint composition for PCM containing 3 to 20% by weight of a solvent. The polyester paint composition for PCM according to claim 1, further comprising one or more additives selected from the group consisting of anti-settling agents, light stabilizers, and curing aids. A coating film formed using the polyester coating composition for PCM of claim 1 or 2. A PCM steel sheet coated with a coating film formed using the PCM polyester paint composition of claim 1 or 2.