KR101869203B1 - Uv-curable coating composition - Google Patents

Abstract

The present invention relates to a UV curable coating composition, and more particularly, to a UV curable coating composition comprising a urethane acrylate resin, a polyfunctional acrylate and a photopolymerization initiator component having a specific combination of absorption wavelengths, It is possible to diversify the application materials and to reduce the defective rate of the deposition process and to solve the problem of environmental pollution which is a disadvantage of the wet plating method The present invention relates to a UV curable coating composition capable of improving wastewater treatment problems.

Description

[0001] UV-CURABLE COATING COMPOSITION [0002]

The present invention relates to a UV curable coating composition, and more particularly, to a UV curable coating composition comprising a urethane acrylate resin, a polyfunctional acrylate and a photopolymerization initiator component having a specific combination of absorption wavelengths, It is possible to diversify the application materials and to reduce the defective rate of the deposition process and to solve the problem of environmental pollution which is a disadvantage of the wet plating method The present invention relates to a UV curable coating composition capable of improving wastewater treatment problems.

The surface coating having a metal texture on a plastic material is lighter than a metal and is widely used as a decorative material for automobiles, furniture, and home appliances due to its excellent appearance such as a metal.

A conventional surface coating method is a wet plating method in which a metal is closely adhered to the surface of a plastic molded article by chemical agents. However, although the wet plating method has a somewhat widened platable material, there is a limitation in the material that it can be applied only to a composite resin including an ABS resin or an ABS resin. In addition, since most of the chemical solutions used for wet plating contain heavy metals, the use of this solution has the potential to provide a direct source of environmental pollution due to industrial wastewater discharge, as well as overpopulation of overhead capital for wastewater purification And the like.

In order to solve the disadvantages of such a wet plating method, various UV-curable coating compositions for the purpose of application to metal or plastic substrates have been proposed (for example, Korean Patent Publication No. 1997-7003397).

It is an object of the present invention to provide a curable coating composition which is excellent in physical properties such as appearance, flowability, adhesion to various substrates, curability, heat resistance and re-coatability and can be applied to various materials, And it is an object of the present invention to provide a coating composition capable of solving environmental pollution problems and wastewater treatment problems which are disadvantages of the wet plating method.

The coating composition of the present invention comprises (A) a urethane acrylate resin, (B) a polyfunctional acrylate, (C) a photopolymerization initiator component, (D) an additive comprising a wetting / leveling agent, and (E) Wherein the photopolymerization initiator component has an absorption wavelength in the range of 250 to 270 nm and 320 to 340 nm, and the wetting / leveling agent is a combination of a polyether-based silicone compound and an acrylate-based silicone compound.

The coating composition according to the present invention can be recycled and can be painted by a coating method such as a showering (Curtain Flow coating), and is excellent in adhesion to BMC and PPS materials of automobile head lamps, Lt; / RTI >

Hereinafter, the present invention will be described in detail.

(A) Urethane Acrylate  Suzy

The urethane acrylate resin (A) contained in the coating composition of the present invention can be obtained, for example, by reacting a compound of an aliphatic isocyanate (for example, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, etc.) (For example, pentaerythritol triacrylate, dipentaerythritol triacrylate, and the like). The weight average molecular weight of the component (A) may be, for example, 1000 to 5000.

In the coating composition of the present invention, the component (A) may be contained in an amount of, for example, 20 to 40% by weight, more specifically 20 to 30% by weight, based on the total weight of the composition. If the content of the component (A) is less than 20% by weight of the total weight of the composition, formation of a cured coating film is difficult and curability and heat resistance may be deteriorated, and if it exceeds 40% by weight, cracks may be caused in the coating film due to excessive curing density.

(B) Multifunctional Acrylate

The polyfunctional acrylate (B) contained in the coating composition of the present invention is an acrylate monomer having two or more (for example, 2 to 6, more specifically, 2 to 3) polymerizable functional groups which are unsaturated groups capable of being polymerized Or oligomers. Examples of the polyfunctional acrylate (B) include 1,6-hexanediol diacrylate (HDDA), 1,6-hexanediol dimethacrylate, At least one selected from the group consisting of trimethylolpropane triacrylate, pentaerythritol triacrylate (PETA) and dipentaerythritol hexaacrylate (DPHA) can be used, , But is not limited thereto.

The coating composition of the present invention may contain the component (B) in an amount of, for example, 10 to 30% by weight, more specifically 10 to 20% by weight, based on the total weight of the composition. If the content of the component (B) is less than 10% by weight of the total weight of the composition, cracking or adhesion of the hard coat film may be caused. On the other hand, if it exceeds 30% by weight, a problem that the curing rate is slowed may occur.

(C) having an absorption wavelength in the range of 250 to 270 nm and 320 to 340 nm The photopolymerization initiator component

The photopolymerization initiator is a component used for curing the film forming component, and the photopolymerization initiator component (C) used in the present invention has an absorption wavelength in the range of 250 to 270 nm and 320 to 340 nm.

As the photopolymerization initiator component (C), a single photopolymerization initiator compound having an absorption wavelength in the range of 250 to 270 nm and 320 to 340 nm may be used. Alternatively, a photopolymerization initiator having an absorption wavelength in the range of 250 to 270 nm and a photopolymerization initiator A combination of a photopolymerization initiator having an absorption wavelength in the range of from 340 nm to 340 nm may be used. An example of a photopolymerization initiator having an absorption wavelength in the range of 250 to 270 nm is benzophenone, and an example of a photopolymerization initiator having an absorption wavelength in the range of 320 to 340 nm is 1-hydroxy-cyclohexylphenylketone. But is not limited thereto.

In the coating composition of the present invention, the component (C) may be contained in an amount of, for example, 1 to 5% by weight, more specifically 1 to 3% by weight, based on the total weight of the composition. If the content of the component (C) is less than 1% by weight of the total weight of the composition, it may lead to deterioration in appearance and poor physical properties due to lowering of the curability and unhardening. If the content exceeds 5% by weight, contamination due to unreacted photopolymerization initiator, It may cause deterioration of adhesiveness and cracking. When an initiator having an absorption wavelength at 250 to 270 nm and an initiator having an absorption wavelength at 320 to 340 nm are used in combination as the component (C), an initiator having an absorption wavelength of 250 to 270 nm The initiator may be used in an amount of, for example, 10 to 80 parts by weight, more specifically 20 to 70 parts by weight.

(D) wetting / Leveling agent  Containing Additives

The coating composition of the present invention comprises an additive component comprising a wetting / leveling agent, wherein the wetting / leveling agent is a combination of a polyether-based silicone compound and an acrylate-based silicone compound. Preferably, polyether-modified polydimethylsiloxane may be used as the polyether-based silicone compound, and silicone diacrylate or silicone polyacrylate may be used as the acrylate-based silicone compound.

When the additive is used singly, the smoothness and adhesion of the coating film are good depending on the kind, but the re-coatability and heat resistance can be lowered. Accordingly, the present invention uses a combination of a polyether-based silicone compound and an acrylate-based silicone compound as a wetting / leveling agent in an additive to improve re-coatability.

In the coating composition of the present invention, each of the polyether-based silicone compound and the acrylate-based silicone compound as the wetting / leveling agent may be contained in an amount of, for example, 0.1 to 1% by weight based on the total weight of the composition. If the content of each of these components is less than 0.1% by weight, there is a problem of poor appearance and poor adhesion. If the content is more than 1% by weight, adherence may deteriorate due to unreacted additives.

The component (D) may further contain components commonly added to the coating composition other than the above-mentioned mixed wetting / leveling agent such as an ultraviolet stabilizer (e.g., HALS), an antioxidant (e.g., phenolic antioxidant) . Each of these additional components may be used in an amount of 0.1 to 1% by weight based on 100% by weight of the total coating composition.

The total amount of the additive component (D) contained in the coating composition of the present invention may be, for example, 0.2 to 5 wt%, more specifically 0.2 to 3 wt%, based on the total weight of the composition.

(E) Solvent

Examples of the solvent (E) contained in the coating composition of the present invention include inert organic solvents commonly used in coating compositions such as alcohols such as methoxypropanol and isopropyl alcohol, ketones such as acetone, ethylacetate, Acetates, or aromatic compounds such as toluene may be used alone or in combination.

In the coating composition of the present invention, the component (E) may be contained in an amount of, for example, 40 to 60% by weight, more specifically 50 to 60% by weight, based on the total weight of the composition. If the content of the component (E) is less than 40% by weight of the total composition, the workability and leveling may be lowered. If the content is more than 60% by weight,

There is no particular limitation on the method for producing the coating composition of the present invention. For example, the components (A) to (E) as described above may be added to a mixing apparatus such as a dissolver or a stirrer, Followed by mixing at an appropriate temperature (for example, room temperature).

The photocurable coating composition of the present invention can be applied to various materials, particularly, but not limited to, a plastic substrate. According to the embodiment of the present invention, the coating composition of the present invention is coated on the surface of such material, dried, and then cured by ultraviolet irradiation to form a coating layer. According to the embodiment of the present invention, the coating composition of the present invention can be applied to automobile parts, for example, a car head lamp.

The present invention is described in more detail by the following examples. However, these embodiments are provided for the purpose of helping understanding of the present invention, but the present invention is not limited thereto.

[ Example ]

(1) Preparation of Coating Composition

A coating composition was prepared with the compositions shown in Tables 1-1 to 1-5 below.

A-1: 6-functional urethane acrylate resin, molecular weight 1800, specific gravity 1.16

A-2: trifunctional urethane acrylate resin, molecular weight (MW) 2400, specific gravity 1.16

B-1: Trifunctional acrylate monomer [PETA]

B-2: 6-functional acrylate monomer [DPHA]

B-3: Bifunctional acrylate monomer [HDDA]

C-1: initiator [1-hydroxy-cyclohexyl phenyl ketone, absorption wavelength: 246, 280, 330 nm, molecular weight: 204, density: 1.18]

C-2: initiator [benzophenone, absorption wavelength: 260 nm, molecular weight: 182, specific gravity: 1.1108]

C-3: initiator [diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide, absorption wavelength: 295, 368, 380, 393 nm]

Molecular weight: 236.3, melting point:> 107.3 ° C

C-4: initiator [alpha amino ketone, absorption wavelength: 230, 304 nm, molecular weight: 279.4]

C-5: initiator [bisacylphosphine, absorption wavelength: 295, 370 nm, molecular weight: 418.5]

C-6: Initiator [alpha amino ketone, absorption wavelength: 233, 324 nm, molecular weight: 366.5]

D-1: wetting / leveling agent [silicone-based, BYK 3530]

D-2: wetting / leveling agent [polyether modified polydimethylsiloxane, OH of 250 mg KOH / g, density of 1.105 g / cm ³ BYK 3535]

D-3: wetting / leveling agent [polyacrylate type silicone compound, Density (20 ° C) 0.95 g / cm ³ , viscosity 117 mm ² / s at 40 ° C, BYK 358N]

D-4: Wetting / leveling agent [Acrylate type silicone compound, Density (20 ° C) 1.05 g / ml, Flash point:> 100 ° C BYK-356

D-5: Wetting / leveling agent [Acrylate type silicone compound, Density (20 ° C) 1.01 g / ml, Flash point: 45 ° C BYK-355

E: Solvent [100% butyl acetate]

(2) Evaluation of Physical Properties of Coating Composition

The ultraviolet curable coating compositions prepared in the above Examples and Comparative Examples were applied to the reflector of automobile headlamps by metal vapor deposition to evaluate their physical properties. A BMC material as a reflector material of a head lamp projection lamp was irradiated with energy of 2000 mj / cm 2 at a position of about 20 cm in air with a high pressure mercury lamp of 180 mW / cm 2 to UV-activate the BMC material, The photocurable coating composition thus prepared was applied to a thickness of 15 mu m by using a sprayer, followed by hot air drying for about 300 seconds at a temperature of 70 DEG C to remove the solvent. Then, the solvent was removed by a high pressure mercury lamp of 180 mW / / Cm < 2 > and cured, and then aluminum was vacuum deposited thereon under a vacuum of 10 < ^-4 > Then, on the surface of the aluminum deposited, the specimens for physical properties test were prepared by applying the examples and the comparative examples under the same UV curing conditions as above. Properties of the following items were evaluated for the prepared specimens, and the results are shown in Tables 2-1 to 2-5 below.

1) Compatibility: The haze of the solution was evaluated by visually observing the manufactured sample

2) Appearance: Evaluate the opacity, crack or smoothness of the coating film by visually checking the test piece.

3) Flowability: A sample is poured into a glass plate according to ASTM D 4400,

4) Adhesiveness: After the deposition, a cross cut tape test was performed according to ASTM D3359

5) Curing property: 500mj / ㎠ After 3PASS, toughening hardening confirmed

6) Heat resistance: Oven 180 ℃ X 24 hours after visual observation

7) Adhesiveness (heat resistance): After the heat resistance test, the cross cut tape test was carried out according to ASTM D3359

8) Re-coatability: After hardening, re-coat after painting

9) Adhesiveness (Recoating): Recoating after undercoating, check for painted, and perform cross-cut tape test according to ASTM D3359.

[X: poor,?: Normal,?: Good,?: Excellent]

CRACK: Crack occurs in hardened film after heat test at high temperature

RAINBOW: After the heat test at high temperature, the color changes depending on the angle of view of the film surface due to the internal uncured material or gas leaching from the material.

ㅡ: No film formation itself

Claims (3)

(A) a urethane acrylate resin,
(B) a polyfunctional acrylate,
(C) a photopolymerization initiator component,
(D) an additive comprising a wetting / leveling agent and
(E) a solvent,
Wherein the photopolymerization initiator component (C) is a combination of a photopolymerization initiator having an absorption wavelength in the range of 250 to 270 nm and a photopolymerization initiator having an absorption wavelength in the range of 320 to 340 nm,
10 to 80 parts by weight of a photopolymerization initiator having an absorption wavelength in the range of 250 to 270 nm is used relative to 100 parts by weight of the photopolymerization initiator having an absorption wavelength in the range of 320 to 340 nm,
Wherein the wetting / leveling agent is a combination of a polyether-based silicone compound and an acrylate-based silicone compound,
An ultraviolet curable coating composition for automobile headlamp reflector coating. The coating composition according to claim 1, wherein the photopolymerization initiator component (C) is a combination of benzophenone and 1-hydroxy-cyclohexyl phenyl ketone. The composition according to claim 1, which comprises 20 to 40 wt% of the urethane acrylate resin (A), 10 to 30 wt% of the polyfunctional acrylate (B), 1 to 5 wt% of the photopolymerization initiator component (C) 0.2 to 5% by weight of an additive (D), and 40 to 60% by weight of a solvent (E).