KR102602457B1 - Coating Composition - Google Patents

Abstract

The present invention relates to a coating composition with excellent weather resistance.

Description

Paint composition {Coating Composition}

The present invention relates to a coating composition with excellent weather resistance.

PCM (Pre-Coated Metal) paint can secure excellent processability, hardness, and scratch resistance, so it is used for various purposes such as home appliances and building materials. In particular, when applied as an exterior material for building materials, the coating film is required to have excellent weather resistance, and research and development are being actively conducted to improve the weather resistance of the paint composition.

For example, Patent Publication No. 2019-0045165 contains core-shell fine particles that contain tetragonal titanium oxide solid solution particles containing a room temperature curable resin and tin and manganese as the nucleus, and have a shell of silicon oxide on the outside of the nucleus. A coating composition is disclosed. However, conventional paint compositions lack weather resistance to prevent deterioration in harsh environments, especially when used in areas with a lot of sunlight or heavy annual precipitation, causing color changes, loss of gloss, and chalking of the paint film. There is a problem where the degree of deterioration is severe.

The present invention provides a coating composition with excellent weather resistance.

The present invention provides a coating composition comprising a polyester resin, a silicone-modified polyester resin, and a melamine resin.

The paint composition according to the present invention has excellent weather resistance and exhibits excellent gloss retention and color retention even when exposed to ultraviolet rays for a long period of time. Therefore, the coating composition of the present invention can be applied to PCM steel sheets for outdoor exterior materials.

Hereinafter, the present invention will be described in detail. However, it is not limited to the following content, and each component may be variously modified or selectively mixed as needed. Accordingly, it should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

“Number average molecular weight” and “weight average molecular weight” used in this specification are measured by common methods known in the art, and can be measured, for example, by GPC (gel permeation chromatograph) method. “Glass transition temperature” ” is measured by a common method known in the art, and can be measured, for example, by differential scanning calorimetry (DSC). Functional groups such as “hydroxyl value” are measured by a common method known in the art. It is measured by, and can be measured by, for example, titration.

The coating composition according to the present invention includes polyester resin, silicone-modified polyester resin, and melamine resin. In addition, the coating composition according to the present invention may further include pigments, solvents, curing accelerators, and additives commonly used in the relevant technical field, if necessary.

polyester resin

The coating composition according to the present invention includes a polyester resin. Polyester resin reacts with a curing agent to form a coating film, provides gloss, and secures the basic properties of the coating film, such as weather resistance, corrosion resistance, processability, chemical resistance, hardness, and adhesion.

The polyester resin can be produced by polymerizing an acid monomer and an alcohol monomer.

The acid monomer may be an aliphatic acid, an aromatic acid, or a mixture thereof. For example, adipic acid, sebacic acid, succinic acid, isophthalic acid, phthalic anhydride, terephthalic acid, trimellitic anhydride. Trimellitic anhydride, benzenetricarboxylic acid anhydride, naphthalene tricarboxylic acid anhydride, etc. can be used, and these can be used alone or in a mixture of two or more types. For example, the acid monomer may be an aliphatic acid monomer.

The alcohol monomer may be a polyfunctional alcohol, an aliphatic alcohol, an aromatic alcohol, or a mixture thereof. For example, ethylene glycol, propylene glycol, 1,2-butylene glycol, neopentyl glycol, 1,6-hexanediol (1 ,6-Hexanediol), Trimethylol propane, Glycerol, Bisphenol-A (BPA), alkoxylated alcohol such as BA320TK, etc. can be used alone or in a mixture of two or more types. You can use it. For example, the alcohol monomer may be a dihydric or trihydric aliphatic alcohol.

The number average molecular weight of the polyester resin may be 1,000 to 4,000 g/mol, for example, 1,800 to 2,000 g/mol, and the weight average molecular weight may be 3,000 to 10,000 g/mol, for example, 5,000 to 7,000 g/mol. . If the number average molecular weight and weight average molecular weight of the polyester resin are less than the above-mentioned range, the coating film may brittle and adhesion and processability may be reduced, and if it exceeds the above-mentioned range, agglomeration may occur during the manufacture of the paint. Compatibility may be reduced.

The glass transition temperature of the polyester resin may be 10 to 45°C, for example, 20 to 30°C. If the glass transition temperature of the polyester resin is less than the above-mentioned range, the flexibility of the resin may increase and chemical resistance and water resistance may be reduced, and if it exceeds the above-mentioned range, the flexibility of the resin may be reduced and the processability of the paint may be reduced.

The hydroxyl value of the polyester resin may be 50 to 75 KOH mg/g, for example, 55 to 70 KOH mg/g, and the solid content may be 50 to 95%, for example, 60 to 80%. If the hydroxyl value of the polyester resin is less than the above-mentioned range, the bonding force may decrease due to a lack of OH groups in the resin, which may reduce water resistance and curability, and if it exceeds the above-mentioned range, OH groups remain in the paint, resulting in excessive bonding in the paint. As this occurs, processability and moldability may decrease.

The content of the polyester resin may be 30 to 60% by weight, for example, 30 to 40% by weight, based on the total weight of the paint composition. When the content of the polyester resin falls within the above-mentioned range, the basic physical properties of the coating film are good, excellent corrosion resistance, chemical resistance, and appearance characteristics can be exhibited, and adhesion to other base layers can be improved.

Silicone modified polyester resin

The coating composition according to the present invention includes a silicone-modified polyester resin. The silicone-modified polyester resin serves to improve the weather resistance of the coating film.

The silicone-modified polyester resin can be produced by copolymerization of a silicone intermediate and a polyester resin. The silicone intermediate may be a polysiloxane resin having a reactive group such as a siloxane group or a methoxy group in the molecule.

The silicone-modified polyester resin has a number average molecular weight of 1,000 to 4,000 g/mol, for example, 1,600 to 2,000 g/mol, and a weight average molecular weight of 5,000 to 12,000 g/mol, for example, 7,000 to 9,000 g/mol. You can. If the number average molecular weight and weight average molecular weight of the silicone-modified polyester resin are less than the above-mentioned range, the coating film may brittle and adhesion to the substrate and processability may be reduced, and if it exceeds the above-mentioned range, agglomeration phenomenon may occur. This may cause compatibility to deteriorate.

The silicone-modified polyester resin may have a glass transition temperature of 5 to 40°C, for example, 10 to 20°C. If the glass transition temperature of the silicone-modified polyester resin is less than the above-mentioned range, chemical resistance and water resistance may be reduced, and if it exceeds the above-mentioned range, the flexibility of the resin may be lowered and the processability of the paint may be reduced.

The silicone-modified polyester resin has a hydroxyl value of 90 to 200 KOHmg/g, for example, 100 to 180 KOHmg/g, a solid content of 50 to 95%, for example, 60 to 80%, and a silicone content (based on solid content) ) may be 15 to 45% by weight, for example 25 to 35% by weight. If the hydroxyl value of the silicone-modified polyester resin is less than the above-mentioned range, reactivity may be reduced and water resistance and curability may be reduced, and if it exceeds the above-mentioned range, processability and moldability may be reduced due to over-bonding. Additionally, if the silicone content is outside the above-mentioned range, compatibility with polyester resin may be reduced.

The content of the silicone-modified polyester resin may be 0.2 to 10% by weight, for example, 0.5 to 2% by weight, based on the total weight of the paint composition. If the content of the silicone-modified polyester resin is outside the above-mentioned range, the compatibility of the paint may decrease, which may result in a decrease in weather resistance (color retention rate, gloss retention rate, and chalking resistance).

melamine resin

The coating composition according to the present invention contains melamine resin. The melamine resin serves to form a stable coating film by causing a curing reaction with the polyester resin component described above.

As the melamine resin, methoxy melamine resin, butoxy melamine resin, methoxy/butoxy mixed melamine resin, etc. can be used, and these can be used alone or in a mixture of two or more types.

The melamine resin may have a weight average molecular weight of 100 to 3,000 g/mol, for example, 300 to 1,000 g/mol, and a solid content of 70 to 100%, for example, 75 to 100%. If the weight average molecular weight of the melamine resin is less than the above-mentioned range, adhesion to the substrate and processability may be reduced, and if it exceeds the above-mentioned range, compatibility may be reduced.

The content of the melamine resin may be 10 to 30% by weight, for example, 15 to 20% by weight, based on the total weight of the paint composition. When the content of the melamine resin satisfies the above-mentioned range, the degree of curing of the coating film may increase and the physical properties of the coating film may be improved.

In the present invention, the mixing ratio (weight ratio) of the polyester resin, the silicone-modified polyester resin, and the melamine resin is 12.5 to 80: 1: 3.5 to 30, for example, 18 to 50: 1: 4 to 15, as another example. It may be 20 to 50:1:6 to 15. When the above three types of resins are mixed in the ratio within the above-mentioned range, an appropriate amount of silicone remains in the coating film, and the silicone-modified polyester resin has a high binding energy and is not easily broken by light, resulting in excellent weather resistance of the coating film. can be secured. If the mixing ratio of the polyester resin to the silicone-modified polyester resin is less than the above-mentioned range, the bond energy may become too strong and processability and weather resistance (color retention rate, gloss retention rate, chalking resistance) may be reduced, and if it exceeds the above-mentioned range, the paint The binding energy of is lowered, so if exposed to strong ultraviolet rays and high temperature and humidity conditions for a long period of time, the weather resistance (color retention rate, gloss retention rate, chalking resistance) of the coating film may deteriorate. In addition, if the mixing ratio of melamine resin to silicone-modified polyester resin is outside the above-mentioned range, weather resistance (color retention rate, gloss retention rate, chalking resistance) may decrease when exposed to strong ultraviolet rays and high temperature and humidity conditions for a long period of time.

pigment

The paint composition according to the present invention may further include pigment. As the pigment, conventional colored pigments known in the art can be used.

Colored pigments can be used to give the paint a desired color or to increase the strength or gloss of the paint film. Colored pigments include organic pigments, inorganic pigments, metallic pigments, aluminum-paste, pearl, etc., and these can be used alone or in combination of two or more. For example, titanium oxide white, cyanine blue, iron oxide red, carbon black, chrome yellow, etc. can be used, and these can be used alone or in combination of two or more.

The content of the pigment may be 1 to 40% by weight, for example, 5 to 35% by weight, based on the total weight of the paint composition. When the content of the pigment satisfies the above-mentioned range, the degree of curing and hiding power of the coating film can be improved.

solvent

The paint composition according to the present invention may further include a solvent. Solvents play a role in improving the workability of paint.

The solvent may be an aromatic hydrocarbon solvent, an ester solvent, an ether solvent, an alcohol solvent, or a mixture thereof. Non-limiting examples of usable solvents include cyclohexanone, xylene, toluene, cellosolve acetate, methyl ethyl ketone, dibasic ester, propylene glycol methyl ether acetate, butyl acetate, ethyl acetate, propylene glycol monomethyl acetate, 3- Methoxy butyl acetate, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, methanol, ethanol, isopropanol, n-butanol, amyl alcohol, butyl carbitol, isophorone or these There are mixed solvents, etc.

The content of the solvent may be a residual amount that satisfies 100% by weight of the total weight of the coating composition, for example, 1 to 30% by weight, for example, 3 to 20% by weight, based on the total weight of the coating composition. When the content of the solvent falls within the above-mentioned range, workability is improved and the coating film can exhibit excellent physical properties.

cure accelerator

The coating composition according to the present invention may further include a curing accelerator. The curing accelerator promotes the curing reaction and improves the cycle of high temperature reliability and continuous workability of the coating film.

As the curing accelerator, amine-based compounds, phosphorus-based compounds, acid compounds, tin-based compounds, etc. may be used. For example, the curing accelerator may be p-toluene sulfonic acid (p-TSA).

The content of the curing accelerator may be 0.1 to 10% by weight, for example, 0.3 to 2% by weight, based on the total weight of the coating composition. If the content of the curing accelerator is outside the above-mentioned range, workability and moldability may be reduced.

additive

The coating composition of the present invention may optionally further include additives commonly used in the paint field within the range that do not impair the inherent properties of the composition. Non-limiting examples of additives that can be used in the present invention include leveling agents, plasticizers, anti-settling agents, waxes, light stabilizers, gloss control agents, etc.

The leveling agent is used to improve the appearance characteristics of the paint film while improving adhesion within the composition by leveling the paint composition so that it is coated evenly and smoothly. The leveling agent may be any conventional leveling agent known in the art without limitation, and acrylic, silicone, polyester, or amine leveling agents may be used.

The antifoam agent plays a role in improving the appearance characteristics of the paint film by suppressing bubbles generated during painting. The antifoaming agent may be any conventional antifoaming agent known in the art without limitation, and a silicone-based or non-silicone-based antifoaming agent may be used.

In addition, anti-settling agents that prevent the paint from settling (e.g., silicon dioxide), waxes that provide slip properties to the surface of the coating film (e.g., paraffin wax), and light stabilizers that absorb radicals generated by ultraviolet rays ( Examples include HALS), curing accelerators that promote curing of the coating surface (e.g., triethylamine, N,N-diethylethanamine), and matting agents that control gloss (e.g., silicon dioxide) can be used.

The additives may be appropriately added within the content range known in the art, for example, they may be included in an amount of 0.1 to 20% by weight based on the total weight of the coating composition. When the content of the additive is within the above-described range, the appearance and hardness of the coating film can be improved.

The present invention will be described in more detail through examples below. However, the following examples are only intended to aid understanding of the present invention, and the scope of the present invention is not limited to the examples in any way.

[Experimental Example 1-12]

The paint compositions of each experimental example were prepared by mixing polyester resin, silicone-modified polyester resin, melamine resin, pigment, solvent, curing accelerator, and additives according to the compositions shown in Tables 1 and 2 below. The unit of usage of each ingredient in Tables 1 and 2 below is parts by weight.

Polyester Resin 1 (PE 1): Mn 2,000, Mw 6,600, Tg 21℃, OHV 60, NV 70%

Polyester Resin 2 (PE 2): Mn 1,800, Mw 5,600, Tg 25℃, OHV 64, NV 70%

Polyester Resin 3 (PE 3): Mn 4,800, Mw 10,000, Tg 15℃, OHV 25, NV 60%

Silicone modified polyester resin 1 (SMP 1): Mn 1,900, Mw 7,700, Tg 15℃, OHV 175.7, NV 70%, Silicon content 33% (wt%/solid)

Silicone modified polyester resin 2 (SMP 2): Mn 1,600, Mw 5,600, Tg 18℃, OHV 107.4, NV 70%, Silicon content 27% (wt%/solid)

Silicone modified polyester resin 3 (SMP 3): Mn 2,550, Mw 17,900, Tg 19℃, OHV 60, NV 62%, Silicon content 26% (wt%/solid)

Melamine Resin 1: Full Methoxy Melamine, Mw 2,000, NV 97%

Melamine Resin 2: Highly methylated melamine, Mw 1,000, NV 76%

Solvent 1: BLACK TINTER

Solvent 2: RED TINTER

Solvent 3: YELLOW TINTER

Solvent 4: WHITE TINTER

Solvent 5: Cyclo Hexanone

Solvent 6: Kocosol #150

Pigment 1: Fumed Silica Sol'N, Fumed Silica D200 (KCC Silicone)

Pigment 2: Aerosil 200 Sol'N, Aerosil R972, Fumed Silica, EVONIK INDUSTRIES AG HERMANY

Cure Accelerator 1: p-TSA Cat 50% Sol'N

Cure accelerator 2: TEA Sol'N

Leveling agent: Thermo Plastic Acryl, NV 62-64%

Antifoam: Polyolefin (SPECTRANSYN 40)

Wax: PARAFFIN WAX

Light stabilizer: Tinuvin 123, HALS

Matting agent: Silicone dioxide

[Physical property evaluation]

The physical properties of the coating compositions prepared according to each experimental example were measured by the following method, and the results are shown in Tables 3 and 4 below.

Processability

According to ASTM D4145, the specimen was bent (0T, 1T, 2T) and tested by holding it in a VICE, and then the crack of the processed area was checked (15x magnifying glass).

Hardness (MEK Rubbing)

After soaking the GUAZE with solvent (MEK), the number of reciprocations with a 1 kg load was measured.

Adhesion (C.C.E.T.)

After making 100 cross cuts horizontally and vertically at 1 mm intervals on the specimen, they were press-fitted at 6 mm, removed with tape, and the peeling condition was evaluated.

pencil hardness

Measurements were made using Mitsubishi Pencil according to ASTM D3363.

(Pencil hardness - 3H > 2H > H > F > HB > B > 2B)

Chemical resistance

After immersion in 5% NaOH and 5% HCL for 24 hours, the appearance of the coating film was observed.

Accelerated Weathering (WOM)

After irradiation for 4,000 hours according to ASTM G155-1, color difference, gloss retention, and chalking were evaluated.

(Light source: 340 nm

Accelerated Weathering (QUV-A)

According to ASTM D4587, color difference, gloss retention, and chalking were evaluated after 4,000 hours of irradiation using Q-LAB's QUV-A TEST.

As confirmed from the results in Tables 3 and 4, the paint composition of Experimental Examples 1-8 using polyester resin, silicone-modified polyester resin, and melamine resin at the mixing ratio according to the present invention had excellent physical properties in all measurement items. indicated. On the other hand, the paint compositions of Experimental Examples 9 and 10 in which the mixing ratio of polyester resin, silicone-modified polyester resin and melamine resin is outside the scope of the present invention, and Experimental Examples 11 and 12 that do not contain polyester resin or silicone-modified polyester resin. In the case of the paint composition, the overall measurement items showed inferior physical properties compared to Experimental Example 1-8.

Claims (5)

A paint composition comprising a polyester resin, a silicone-modified polyester resin, and a melamine resin, wherein the mixing ratio (weight ratio) of the polyester resin, the silicone-modified polyester resin, and the melamine resin is 18 to 50:1:4 to 15. ,
The silicone-modified polyester resin has a glass transition temperature of 5 to 40° C., a hydroxyl value of 90 to 200 KOHmg/g, a solid content of 50 to 95%, and a silicone content (based on solids) of 15 to 45% by weight. Paint composition. The method of claim 1, wherein the polyester resin has a number average molecular weight of 1,000 to 4,000 g/mol, a weight average molecular weight of 3,000 to 10,000 g/mol, a glass transition temperature of 10 to 45° C., and a hydroxyl value of 50 to 50. A coating composition having 75 KOHmg/g and a solid content of 50 to 95%. The coating composition according to claim 1, wherein the silicone-modified polyester resin has a number average molecular weight of 1,000 to 4,000 g/mol and a weight average molecular weight of 5,000 to 12,000 g/mol. The coating composition according to claim 1, wherein the melamine resin has a weight average molecular weight of 100 to 3,000 g/mol and a solid content of 70 to 100%. The paint composition according to claim 1, comprising 30 to 60% by weight of the polyester resin, 0.2 to 10% by weight of the silicone-modified polyester resin, and 10 to 30% by weight of the melamine resin, based on the total weight of the paint composition.