KR101655621B1 - A clear coat composition with antipollution - Google Patents

Abstract

The present invention relates to a clear coating composition having excellent antifouling property, and a reactive silicone additive having compatibility with the polyol resin and an isocyanate curing agent at the same time is used as a subject, using a combination of an acrylic polyol resin having a specific hydroxyl value and a polyester polyol resin The present invention relates to a clear coating composition which is easy to clean and which has excellent water repellency and oil repellency by simultaneously imparting water repellency and oil repellency to the coating film and is free from pollution and which removes contaminants upon washing.

Description

[0001] The present invention relates to a clear coat composition with antipollution,

The present invention relates to a clear coating composition having excellent antifouling property, and a reactive silicone additive having compatibility with the polyol resin and an isocyanate curing agent at the same time is used as a subject, while using a blend of an acrylic polyol resin having a specific hydroxyl value and a polyester polyol resin as a subject The present invention relates to a clear coating composition which is easy to clean and which has excellent water repellency and oil repellency by simultaneously imparting water repellency and oil repellency to the coating film and is free from pollution and which removes contaminants upon washing.

In recent years, automobiles are becoming increasingly demanding for functional parts as a part of high-end. Especially, in the case of a bumper which is located nearest to the road surface (road) among the automobile parts and is greatly affected by pollution (mud, insect, etc.) during driving, the tendency to demand the antifouling function is increasing. In case that the pollution mark is not easily removed when the pollution is removed, there is a possibility that the scratch and damage of the coating film are likely to occur during the over-polish process. However, development of an antifouling paint Is required.

Currently, automotive parts are painted with 3-coat 1 baking method in which primer coating for attaching to the material, base coating for imparting color, and transparent coating are applied. In the present invention, the antifouling performance is to be imparted to the transparent paint (clear) which is the uppermost layer.

There are various ways to implement the antifouling performance at present, and each method and advantages and disadvantages are as follows.

First, there is a method of making a super water repellent body by giving a certain pattern of nano size by using inorganic particles on the surface with a lotus effect, thereby facilitating the removal of contaminants. [Patent Literature 1] According to the method of Patent Document 1, water repellency is excellent, but there are limitations in realizing a painting operation.

In addition, there is a method of preventing pollutants and / or smudges by imparting a hydrophilic performance, not a water repellency. [Patent Document 2] According to the method of Patent Document 2, there is a difficulty in satisfying the reliability (water resistance, weather resistance, etc.) required in a paint for plastic parts such as an automobile bumper.

In addition, there is a method of realizing contamination prevention by imparting water repellency by using a fluorine additive manufactured by 3M, Du Pont or the like as the most general method. [Patent Document 3] However, there is a limitation in the use amount due to compatibility with resins used in automotive parts paints, and even if the initial antifouling performance is implemented, the antifouling performance is deteriorated over time have.

Korean Patent Laid-Open No. 10-2012-0019545 "Method for producing superhydrophobic polymer film" Japanese Patent Laid-Open No. 09-124715 "Process for producing 2-hydroxyethyl methacrylate polymer and functional contact lens" Korean Patent Laid-Open No. 10-2005-0041035 "Fluorine-based amphoteric polymer for surface coating and method for producing the same" Korean Patent No. 10-0989353 "Water-repellent coating composition for wiper excellent in stability and yield"

It is an object of the present invention to provide a clear coating composition in which the initial antifouling performance is continuously maintained while having reliability (antifouling property, chemical resistance, weather resistance, etc.) and appearance required for a plastic part paint.

In order to solve the above problems,

In a clear coating composition comprising a polyol resin, a two-pack type isocyanate curing agent and a common additive,

Wherein the polyol resin comprises a mixture of an acrylic polyol resin and a polyester polyol resin,

And 0.5 to 3 parts by weight of a polyacrylate modified with a siloxane as a reactive silicon additive, based on 100 parts by weight of the solid content of the polyol resin.

The coating composition of the present invention is excellent in compatibility with a paint for plastic parts such as an automobile bumper. Accordingly, there is an effect of satisfying the reliability (resistance to oil, chemical resistance, weather resistance, etc.) required for a plastic part paint.

In addition, the coating composition of the present invention can realize the appearance (smoothness, gloss) possessed by the coating material for plastic parts, and does not lower the paint workability.

In addition, the coating composition of the present invention has an easy-clean performance in which an antifouling performance is imparted and is not easily contaminated, and a contaminated coating film is easily cleaned.

The present invention is applied to the uppermost transparent coating (clear paint) in a 3-coat 1 baking (3 Coat 1 Baking) coating in which a primer coating for attachment to component materials, a base coating for imparting hue, and a clear coating are applied To a clear coating composition.

The coating composition of the present invention comprises a combination of an acrylic polyol resin and a polyester polyol resin as a main resin and includes a specific reactive silicone additive excellent in compatibility with the polyol resin to activate the reaction with an isocyanate curing agent, The water repellent performance is imparted by giving hydrophobicity, and the isoclinic performance for easily removing contaminants at the time of washing is given at the same time.

Each composition constituting the clear paint composition according to the present invention will be described in more detail as follows.

1) Polyol resin

The coating composition of the present invention comprises a polyol resin as a main resin. In the present invention, an acrylic polyol resin having a different molecular weight and hydroxyl value from the polyester polyol resin is mixed at a predetermined ratio.

Specifically, the polyol resin of the present invention is an acrylic polyol resin A having a weight average molecular weight of 3,000 to 3,500 and an OH value of 135 to 145 mg KOH / g; An acrylic polyol resin B having a weight average molecular weight of 10,000 to 12,000 and an OH value of 70 to 80 mg KOH / g; And a mixture of a polyester polyol resin having a weight average molecular weight of 2,000 to 3,000 and an OH value of 110 to 120 mg KOH / g is used. As a result, the reliability (water resistance, weather resistance, etc.) required for the clear paint is satisfied, and appearance and painting workability are improved. Preferably, the polyester polyol resin has a linear structure, rather than a polyester polyol resin having a net-like network structure such as an acrylic polyol, which is excellent in cracking, bending property, chipping resistance, It is better to give a surname.

More specifically, the polyol resin of the present invention is mixed with 40 to 60% by weight of an acrylic polyol resin A, 10 to 30% by weight of an acrylic polyol resin B and 20 to 40% by weight of a polyester polyol resin. In the present invention, by limiting the hydroxyl value of the acrylic polyol resins A and B and the polyester polyol resin contained in the main resin to a specific range and by limiting the content of the polyol resin, an isocyanate curing agent is reacted to obtain an appropriate level of strength Lt; RTI ID = 0.0 > urethane < / RTI > bonds. If the content of the acrylic polyol resin A is less than 40 wt%, the hardness and durability (reliability) of the dried coating film may deteriorate. If the content of the acrylic polyol resin A exceeds 60 wt%, the coating film may crack and the chipping resistance may deteriorate . When the content of the acrylic polyol resin B is less than 10% by weight, there is a problem that appearance (leveling) is lowered. When the content is more than 30% by weight, the acrylic polyol A is relatively decreased in weight and the hardness is lowered. If the content of the polyester polyol resin is less than 20% by weight, there is a problem that the chipping resistance is lowered due to the formation of a hard coating film. If the content is more than 40% by weight, the dry composition is deteriorated and the initial dry coating film becomes dry and sticky.

2) Hardener

The coating compositions of the present invention comprise conventional aliphatic or aromatic isocyanate curing agents in order to react with the polyol resin to form urethane.

Specifically, the isocyanate curing agent is selected from the group consisting of hexamethylene diisocyanate (HDI), hexamethylene diisocyanate trimer (HDT), isophorone diisocyanate (IPDI), cyclohexylmethane diisocyanate (H12MDI) At least one non-sulfur-modified polyisocyanate selected from methylene diphenyl diisocyanate (MDI), and toluene diisocyanate (TDI) can be used. More preferably, the hexamethylene diisocyanate trimer (HDT) is used as the curing agent in consideration of the OH value of the coating material, the compatibility, the drying speed, and the like.

The isocyanate curing agent stoichiometrically reacts with the polyol resin at an equivalent ratio of 1: 1 to form a urethane bond. In order to allow the hydroxyl groups (OH) present in the polyol resin to react, an excess of isocyanate (NCO) good. That is, the equivalent ratio of [OH]: [NCO] is preferably kept in the range of 1: 1.05-1.1.

If the content of the isocyanate curing agent is limited to a weight, the isocyanate curing agent is included in a range of 50 to 70 parts by weight based on 100 parts by weight of the solid content of the polyol resin. If the content of the isocyanate curing agent is less than the above range, there is a problem that the stain resistance of the paint is deteriorated due to the presence of the unreacted polyol resin. If the content of the isocyanate hardener exceeds the above range, the curing proceeds rapidly, A phenomenon may occur or a coating film may be shrunk.

3) Reactive silicone

The coating composition of the present invention comprises a polyacrylate modified with a siloxane as a reactive silicone additive.

Specifically, the reactive silicone additive has a chemical structure in which a side chain of a polysiloxane is bonded to an acrylate back bone as shown in the following structural formula, and the hydroxyl value (OH value) is 20 to 40 mg KOH / g.

[constitutional formula]

As can be seen from the structural formula, the siloxane-modified polyacrylate has the hydrophilic and lipophilic groups at the same time in the molecular structure, so that the water repellency and oil repellency of the coating film can be simultaneously improved.

That is, since the polyacrylate modified with the siloxane contains a hydroxyl group (OH) in the molecular structure, the siloxane modified polyacrylate is excellent in compatibility with a polyol resin or an isocyanate curing agent. Further, the polyacrylate floats on the surface of the coating film, Slip) is applied to the surface of the film, so that foreign matter contaminated with the film is easily removed together with water. In addition, by incorporating the siloxane-modified polyacrylate into the coating composition, it is possible to improve the wetting property, the leveling property, the surface slip property, the water resistance (whitening prevention), the tack resistance, the weather resistance, the graffiti prevention and the tape releasing Can be obtained.

The polyacrylate modified with the siloxane as the reactive silicone additive may be contained in an amount of 0.5 to 3 parts by weight based on 100 parts by weight of the solid content of the polyol resin. If the content of the reactive silicone is less than 0.5 parts by weight, the effect obtained by the incorporation of the polyacrylate modified with the siloxane can not be expected at all. If the amount exceeds 3 parts by weight, the compatibility with other component ingredients is lowered, have.

4) Other additives

The coating composition of the present invention may contain a curing catalyst, a thickener, a leveling agent and a UV stabilizer as conventional additives.

The curing catalyst helps the urethane bond to be formed by the reaction of hydroxyl group and isocyanate in the course of thermosetting, and a urethane curing catalyst widely known in the art can be used. Examples of the curing catalyst include organotin-based catalysts such as methyltin, butyltin, and octyltin. The curing catalyst may be used in an amount of 0.005 to 0.01 part by weight based on 100 parts by weight of the solid content of the polyol resin.

The thickener may be used to prevent sagging of the coating film during coating and to improve coating workability. As the thickener, it is preferable to select and use it without affecting the performance of the coating film such as yellowing and gloss dropout, and a urea type thickener can be used preferably. The thickener may be used in an amount of 1 to 2 parts by weight based on 100 parts by weight of the solid content of the polyol resin.

The leveling agent is used to prevent orange peel. Since the coating composition of the present invention has a high gloss specification, when the orange peel occurs on the surface of the coated film, the linearity of the coating film may be deteriorated, so that the orange peel is prevented by lowering the surface tension. The leveling agent may be, for example, a polyether-modified methylpolysiloxane type, and may be used in an amount of 0.2 to 0.5 parts by weight based on 100 parts by weight of the solid content of the polyol resin.

The UV stabilizer is used to prevent premature thermal curing by ultraviolet rays. As the UV stabilizer, for example, hydroxyphenylbenzotriazole, hydroxyphenyltriazine and the like may be used as the UV absorber (first stabilizer). Also, as the UV stabilizer, a hindered amine light stabilizer (HALS) may be used as a radical scavenger (second stabilizer). Preferably, a UV absorber (first stabilizer) and a radical scavenger (second stabilizer) may be mixed in a weight ratio of 2: 1 as the UV stabilizer. The UV stabilizer may be used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the solid content of the polyol resin.

5) Solvent

The coating composition of the present invention includes a solvent to improve the adhesion to the clear and intermediate color coating by controlling the dissolving power and the evaporation rate at the time of coating, and to make the appearance and coating workability good. The solvent may be appropriately selected from alcohols, ketones, esters, hydrocarbons, and the like as an organic solvent ordinarily used in the art. The solvent may be used in an amount of 50 to 60 parts by weight based on 100 parts by weight of the solid content of the polyol resin.

The present invention will now be described in more detail with reference to the following examples, but the present invention is not limited thereto.

[Example]

Examples and Comparative Examples 1 to 4. Preparation of Clear Coating Composition

A clear coating composition was prepared by mixing a resin, a curing agent, a reactive silicone additive, and conventional additives in a composition ratio as shown in Table 1 below.

[Composition composition]

(1) Acrylic polyol-A: Mw of 3,400, hydroxyl value of 140 mg KOH / g, glass transition temperature (Tg) of 49.9 ° C, nonvolatile content (150 ° C, BAc)

(MIBK / Kocosol # 100) (2) Acrylic polyol-B: weight average molecular weight (Mw) 11,000, hydroxyl value 78 mg KOH / g, non- volatile matter content

(3) Polyester polyol: weight average molecular weight (Mw) 2,500, hydroxyl value 116 mg KOH / g, nonvolatile matter content (150 DEG C, 30 minutes) 80% (in BAc)

(4) Isocyanate Hardener: Hexamethylene diisocyanate trimer (HDT)

(5) Reactive silicone: acrylate modified polyacrylate modified with siloxane having side chains of polysiloxane bonded to the back bone, hydroxyl value of 30 mg KOH / g

(6) Curing catalyst: Organotin catalyst

(7) Thickener: urea type thickener

(8) Leveling agent: Leveling agent of polyether-modified methylpolysiloxane type

(9) UV stabilizer: a mixture of hydroxyphenylbenzotriazole and HALS (2: 1 weight ratio)

(10) Solvent: hydrocarbon type, ester type, ketone type

division Comparative example Example One 2 3 4 Suzy
(weight%) Acrylic polyol-A 50 45 40 30 50 Acrylic polyol-B 50 45 40 50 20 Polyester Polyol 0 10 20 20 30

additive*
(Parts by weight) Isocyanate curing agent 30 30 30 30 30 Reactive silicon 0 0 2 2 2 Curing catalyst 0.01 0.01 0.01 0.01 0.01 Thickener One One One One One Leveling agent 0.2 0.2 0.2 0.2 0.2 UV stabilizer 0.2 0.2 0.2 0.2 0.2 solvent 60 60 60 60 60 * Additive: The content of each additive is expressed in parts by weight based on 100 parts by weight of the solid content of the resin.

[Experimental Example]

Experimental Example 1. Measurement of Physical Properties of Coating Film

The coating compositions prepared in the above Examples and Comparative Examples 1 to 4 were spray coated on the surface of the base material and then allowed to stand at room temperature for 5 to 10 minutes and then dried in a drier at 85 to 5 ° C for 30 minutes to prepare test coating films .

The physical properties of each coating film were measured by the following experimental methods, and the results are shown in Table 2 below.

[Experimental Method]

(1) Flexibility: It is held for 24 hours under the condition of temperature (23 ㅁ 2 ℃) and humidity (50 ㅁ 5%), bending it against MANDRELL (round bar) and checking the surface condition of the film. (Diameter of round bar: 13.00 ㅁ 0.5 mm)

(2) Gloss: Measured at 60 이용 using a gloss meter manufactured by BYK GARDNER.

(3) Chipping resistance: Shooting Distance (100 ㎜), Shooting Angle (45 ㅀ), Shooting

Pressure (4.0 kgf), The test was carried out under the conditions of Test Temperature [room temperature (23 ℃), -40 ℃], granite [50 g (JIS Crushed gravel No 7 stone, 2.5 ~ 5 ㎜ 350 ~ 400, reusable up to 8 times) SAE J 400 standard) to measure chipping marks.

(4) Contact angle: The contact angle is measured after 10 seconds and 60 seconds after dropping DIW onto the coating film.

(5) Decontamination property: The stain test solution (KS A0090 + DIW 1: 1 mixture solution) was applied to the coating film and allowed to stand for 24 hours.

(6) Water resistance: Change in appearance (discoloration, cracking, swelling, etc.) after leaving the coating film in a 40 ° C chamber filled with water for 240 hours

(5) Weatherability: Appearance change after 2500kJ / ㎡ irradiation according to SAE J1960

division Comparative example Example One 2 3 4 Flexibility NG NG Good Good Good Gloss (60 °) 92 91 90 90 94 Chipping resistance NG NG NG Good Good Initial contact angle (°) 72-74 73-75 91-93 90-91 90-93 Decontamination property NG NG Good Good Good Water resistance Good Good Good Good Good Weatherability NG Good Good NG Good

Experimental Example 2 Car Washer Test

The coated film was mounted on a test stand, and the prescribed DUST liquid was stirred and continuously sprayed. A polystyrene brush was subjected to 10 cycles of reciprocating test at a moving speed of 5 m / min. After the evaluation, the specimen was cleaned with soapy water, left at room temperature, and then the surface foreign matter was removed with an organic cleaning agent. The color difference change, gloss retention ratio, and contact angle change ratio before and after the auto car wash test were respectively calculated and shown in Table 3 below.

[Experimental Method]

(1) Change in color difference: Measurement of ΔE after measuring the surface of the coating film with a spin sphere

(2) Gloss retention rate: It indicates the degree of gloss maintained at 60 이용 by using a gloss meter manufactured by BYK GARDNER.

(3) Contact angle retention rate: The degree of retention of the contact angle measured by the contact angle measuring instrument.

division Comparative example Example One 2 3 4 Auto washability Color difference change (ΔE) 0.03 0.14 0.04 0.21 0.05 Gloss retention (%) 90 84 88 84 92 Contact angle retention (%) 78 85 79 75 88 Auto washability after weathering test Color difference change (ΔE) 054 0.66 0.53 0.94 0.63 Gloss retention (%) 88 74 79 85 87 Contact angle retention (%) 58 65 60 65 86

According to the results shown in Tables 2 and 3, the Example shows a two-pack clear coating composition comprising a main resin composed of an acrylic polyol resin and a polyester polyol resin and a polyacrylate modified with siloxane in a predetermined composition ratio , Water resistance and weather resistance were good, and the decontamination performance was excellent. Also, the autochromic test showed excellent color difference change, gloss retention rate and contact angle retention ratio, and it showed a gloss retention ratio of 87% or more and a contact angle retention ratio of 86% or more even in the auto carburization test after weathering.

On the contrary, Comparative Examples 1 and 2 do not include a polyester polyol resin as the main resin (1), and do not include a reactive silicone additive of a polyacrylate modified with a siloxane. The coating composition is excellent in flexibility, (1) is poor, and the initial contact angle is low.

In addition, Comparative Examples 3 to 4 are coating compositions containing a reactive silicone additive of polyacrylate modified with a siloxane with an excessive content of an acrylic polyol resin B, and have poor chipping resistance (3) or weather resistance (4) It is confirmed that the contact angle retention ratio is low in the auto car wash test and the auto car wash test after the weathering test.

Claims (5)

In a clear coating composition comprising a polyol resin, a two-pack type isocyanate curing agent and a common additive,
40 to 60% by weight of an acrylic polyol resin A having a weight average molecular weight of 3,000 to 3,500 and an OH value of 135 to 145 mg KOH / g; 10 to 30% by weight of an acrylic polyol resin B having a weight average molecular weight of 10,000 to 12,000 and an OH value of 70 to 80 mg KOH / g; And 20 to 40% by weight of a polyester polyol resin having a weight average molecular weight of 2,000 to 3,000 and a hydroxyl value (OH value) of 110 to 120 mg KOH / g,
And 0.5 to 3 parts by weight of a reactive silicone additive in which a side chain of the polysiloxane is bonded to the acrylate main chain, based on 100 parts by weight of the solid content of the polyol resin.
delete The method according to claim 1,
Wherein the reactive silicone additive is a polyacrylate modified with a siloxane having a hydroxyl value (OH value) of 20 to 40 mg mg KOH / g.
The method according to claim 1,
The two-pack type isocyanate curing agent may be at least one selected from the group consisting of hexamethylene diisocyanate (HDI), hexamethylene diisocyanate trimer (HDT), isophorone diisocyanate (IPDI), cyclohexyl methane diisocyanate (H12MDI), methylene diphenyl diisocyanate ), And toluene diisocyanate (TDI).
The method according to claim 1,
Wherein the conventional additives further include at least one selected from the group consisting of a curing catalyst, a thickener, a leveling agent, and a UV stabilizer.