KR20060078973A - Two component under coating composition for automotive bumper - Google Patents

Abstract

The present invention provides an undercoat coating composition of elastomer modified polypropylene for an automobile bumper comprising a chlorinated polyolefin-modified acrylic resin, a chlorinated polyolefin resin, a polyester resin, titanium dioxide and barium sulfate, an additive and a solvent. It is useful as a bumper for automobiles because it has excellent adhesiveness when painting, has excellent filling property against defects of materials, and excellent polishing property when polishing after painting.

Description

Two component under coating composition for automotive bumper

The present invention relates to an undercoat composition for automobile bumpers, and more particularly, has excellent adhesion to elastomeric modified polypropylene (hereinafter referred to as EMPP) materials for automobile bumpers, and has excellent fillability and abrasiveness against defects of materials. It is a composition of the two-component undercoat film for automobile bumpers.

In Korea, bumpers for automobile bumpers are mostly applied with a one-component thin film paint. However, the one-component thin-film paint has a disadvantage in that it is impossible to fill the surface of the bumper material due to a drop in the injection technology of the bumper material or due to careless storage. Therefore, a two-component thick film paint is required when the technology of the material falls. .

The bumper material EMPP has low surface tension, which makes it difficult to attach the material. Therefore, conventional paints have secured adhesion by applying cloned polyolefin (hereinafter referred to as CPO) resin, but due to the characteristics of the CPO resin, the material content and abrasive properties This is very bad.

Therefore, the present inventors are trying to solve the problems of the conventional thin film type undercoat composition based on CPO resin, and as a result of using a mixture of CPO-modified acrylic resin, CPO resin, and polyester resin, as well as excellent adhesion and filling properties And it was found that the polishing property is excellent to complete the present invention.

Accordingly, it is an object of the present invention to provide an undercoat coating composition for automobile bumpers that can improve not only adhesion but also filling and polishing properties.

The undercoat composition for automobile bumpers of the present invention for achieving the above object is 20-40% by weight of chlorinated polyolefin-modified acrylic resin, 5-15% by weight of chlorinated polyolefin resin, 1-3% by weight of polyester resin, pigment A main body comprising 30-40 wt%, 15-25 wt% of a solvent, 1-3 wt% of an additive, and 1-3 wt% of a curing catalyst; And

It comprises a curing agent comprising a polyisocyanate, characterized in that the weight ratio of the curing agent to the main portion of 100: 1 ~ 10.

The present invention will be described in more detail as follows.

In the system coating for automobile bumpers, it consists of undercoat / coloredness / transparence, but the physical properties related to adhesion to the material depend on the physical properties of the undercoat. In Korea, there is no problem due to the development of the injection technology of bumper materials, but when the injection technology is poor or the management level of the material is low, many defects occur in the material, and the one-component thin film currently used cannot fill these defects.

Looking at the coating composition of the present invention for this purpose in detail as follows.

A. Topics

(1) CPO modified acrylic resin

In the undercoat composition for automobile bumpers of this invention, a CPO modified acrylic resin is used first. The CPO resin used in the past has excellent adhesion to the material, but has very poor compatibility with other resins, poor dispersibility, and high self-viscosity. Therefore, in the present invention, CPO modified acrylic resin is used to have excellent dispersibility and compatibility while having excellent adhesion to automobile bumper materials such as CPO resin.

The CPO-modified acrylic resin according to the present invention preferably has a hydroxyl value of 15-45 mgKOH, a molecular weight of 40000-100000 and a solid content of 35-65%. When the molecular weight is out of the above range, it is outside the viscosity range of the preferred resin, and when the hydroxyl value is less than 15 mgKOH, the degree of crosslinking of the coating film is lowered. If it exceeds 65%, the resin viscosity becomes high, making it difficult to use.

The content of such CPO-modified acrylic resin is 20-40% by weight, preferably 30-40% by weight of the total coating composition, when the content is less than 20% by weight, the adhesion to the material is poor, and when the content is 40% by weight or more, This separation does not compensate for defects in the material.                     

The CPO modified acrylic resin according to the present invention is particularly preferably used by mixing a CPO modified acrylic resin (type A) having excellent adhesion and a CPO modified acrylic resin (type B) having excellent flexibility. Type A is preferably CPO modified acrylic resin having a hydroxyl value of 25-35mgKOH, molecular weight of 40000-60000 and solid content of 40-50% to improve adhesion, and type B is 10-30mgKOH to improve the flexibility It is preferable to use a CPO modified acrylic resin having a hydroxyl value, a molecular weight of 70000-90000 and a solid content of 30-50%. When the A and B types are mixed, the use of the content ratio of A type: B type = 1: 0.8-1.2 indicates excellent physical properties in adhesion, flexibility, dispersibility, compatibility, and the like.

(2) CPO resin

The undercoat composition for automobile bumpers of the present invention uses CPO resin to enhance adhesion to EMPP.

The CPO resin according to the present invention preferably has a solid content of 10-40% and a molecular weight of 50000-100000, more preferably a solid content of 15-35% and a molecular weight of 50000-80000. When the molecular weight is out of the above range, it is out of the viscosity range of the preferred resin, and if the solid content is less than 15%, the solid content is low, making it difficult to construct a paint, and if it exceeds 35%, the resin viscosity is high, making it difficult to use.

In addition, the content is 5 to 15% by weight of the total coating composition, if the content is less than 5% by weight, the adhesive force is lowered, and when the content exceeds 15% by weight, the total solid content is lowered, the filling properties are lowered.

(3) polyester resin

The undercoat composition for automobile bumpers of the present invention uses a polyester resin for impact reinforcement and flexibility of the undercoat composition.

The polyester resin according to the present invention has a solid content of 60-90% and a molecular weight of 1000-5000, more preferably 75-85% solids and a molecular weight of 1000-5000. In addition, the content is 1-3% by weight of the total coating composition, if the content is less than 1% by weight, the flexibility of the coating is weakened and the hardness of the coating is increased, so that the cracking phenomenon occurs. And a phenomenon in which water resistance is poor.

(4) pigment

The undercoat composition for automobile bumpers of the present invention uses at least one pigment selected from the group consisting of titanium dioxide, barium sulfate and talc. Titanium dioxide has excellent concealability and dispersibility, while talc or barium sulfate has excellent fillability and abrasiveness, and may be used by mixing one or more of these pigments in a required ratio. The content is 30-40% by weight of the total coating composition, if the content is less than 30% by weight, the fillability and abrasiveness is inferior; when the content is more than 40% by weight, the adhesion to the material or adhesion to the color Flexibility and impact resistance deteriorate.

(5) solvent

The undercoat coating composition for automobile bumpers of the present invention can be used a conventional solvent used in the coating composition, preferably an aromatic hydrocarbon. The aromatic hydrocarbon solvent includes benzene, toluene, xylene, cocosol (KOCOSOL) or mixtures thereof. The content is 10-30 wt%, preferably 15-25 wt% in the total coating composition. If the solvent is used excessively, the relative solid content in the coating composition is lowered, so that the filling and salvage properties of the coating are lowered, and when the amount of the solvent used is small, the solvent dissolves in the paint, which causes dust phenomenon or poor appearance. May occur.

(6) additive

The undercoat coating composition for automobile bumpers of the present invention may use a sedimentation inhibitor that prevents the settling of the dispersant and pigment to improve the dispersibility as an additive and to improve the stability of the paint.

Dispersants and anti-settling agents are used in the dispersing process, which is the manufacturing process of the paint, to stabilize the pigments in the paint and to prevent the settling of the pigments during storage. In the present invention, a known general dispersant may be used, and preferably, an alkyl ammonium salt-based dispersant of a block copolymer having an acidic group is used. The antisettling agent may also use a known general dispersant, and preferably a denatured nucleite-based antisettling agent. The amount of the dispersant and the anti-settling agent used is 1-3% by weight of the total coating composition, which is reduced when the content exceeds 3% by weight, and when the content is less than 1% by weight, precipitation of the pigment occurs during storage.

(7) curing catalyst

The coating composition of the present invention uses a curing catalyst for promoting the curing by promoting the urethane reaction which is a bond between the hydroxyl group of the resin and the isocyanate of the curing agent. The composition of the present invention preferably uses at least one curing catalyst selected from the group consisting of tetramethylbutanediamine, bicyclooctane, dibutyltindilaurate, triethylenediamine, zinc octoate and calcium octoate. The amount of the curing catalyst used is 1-3% by weight of the total coating composition diluted to 0.5% in the solvent. If the content is less than 1% by weight, the curing and drying are poor, and if the content exceeds 3% by weight, the pot life (that is, workable) Time) may be shortened and the paint may gel.

B. Curing agent part: polyisocyanate

The undercoat coating composition for automobile bumpers of the present invention uses polyisocyanate for the purpose of curing the composition. The isocyanate functional group of the polyisocyanate reacts with the hydroxyl group of the CPO modified acrylic resin and the polyester resin to form a urethane bond.

Polyisocyanates according to the invention have solids of 80-100% and NCO values of 10-15%. Most preferred polyisocyanates include hexamethylene diisocyanate, xylene diisocyanate and isophorone diisocyanate which are excellent in yellowing resistance and light resistance.

The polyisocyanate according to the present invention may be diluted with a suitable solvent and stored in a separate container, followed by sufficient stirring just before use. The polyisocyanate diluent is hereinafter referred to as curing agent. The dilution ratio of the polyisocyanate dilution solution can be determined by calculating the urethane reaction in equivalent weight equivalents by combining the hydroxyl group of the resin and the isocyanate functional group of the curing agent when the main mixture mixture and the polyisocyanate dilution solution are mixed. If the mixing ratio is more or less than the equivalent weight equivalents, poor coating properties due to crosslinking failure, and durability is not guaranteed. The mixing ratio of 100: 1 to 10 is appropriate based on the weight ratio of the hardener to the main portion. If it is out of the mixing ratio range, the coating film properties decrease due to poor crosslinking.

Hereinafter, the present invention will be described in detail with reference to the following Examples, which are not intended to limit the scope of the present invention.

Examples 1-4 and Comparative Examples 1-2

Next, a coating composition was prepared in a composition as shown in Table 1 below. Here, the pigment dispersing process was carried out separately. Specifically, a dispersing agent in the form of alkylammonium salt was added to xylene as an aromatic solvent in a 1 L tin can, and the pigment was wetted, and CPO-modified acrylic resin was added and stirred sufficiently. After stirring, the mixed solution and the dispersing beads were added at a volume ratio of 1: 1 (volume ratio), and then dispersed in the disperser (RED DEVIL) for at least 1 hour. The end of dispersion was terminated when the particle size of the pigment is 5㎛ or less, wherein the particle size of the pigment was measured using a particle size meter of Sheen.

The CPO-modified acrylic resin, polyester resin, additives, solvents, and the like were added to the mill base prepared as described above in Table 1, followed by stirring for 30 minutes or more. After the preparation of the composition was completed, the filter was used as the bumper.

Experimental Example

The coating composition obtained according to Examples 1 to 4 and Comparative Examples 1 to 2 was mixed with a curing agent to apply the coating composition to a coating material (car bumper material) using a spray gun, followed by baking at 80 ° C. for 30 minutes, followed by filling. Performance and abrasiveness were measured, and the gloss, appearance, adhesiveness, bendability, impact resistance, and water resistance were measured by applying color and transparent paint thereon, and the results are shown in Table 2 below.

Specific measurement method of the physical properties is as follows.

(1) Gloss: Measured at 60 using BYK GARDNER measuring instrument.

(2) Appearance: Visually determined.

(3) Adhesion: Draw a checkerboard scale 1010 by 2mm and perform transparent tape compression test.

(4) Flexibility: Measured by bending 180 degrees around a 13mm round bar.

(5) Impact resistance: Measured by dropping the weight of 1kg from the height of 50cm with a dupont impactor.

(6) Water resistance: Measured by dipping in water at 40 ° C. for 240 hours.

(7) Filling property: # 200 Sandpaper painted on the material scratched to observe the appearance.

(8) Grindability: Grind with # 1000 sandpaper and observe the degree of grinding.                     

As described in detail above, the two-component coating composition comprising a mixture of two kinds of CPO-modified acrylic resins according to the present invention as a main resin, wherein the two-component coating composition comprising a pigment such as titanium dioxide and barium sulfate in an appropriate ratio is used for the EMPP for bumper. As it has excellent adhesion to the material and at the same time has a filling and polishing property against the material defects, it is useful as an undercoat for automobile bumpers.

Claims (6)

20-40 wt% chlorinated polyolefin modified acrylic resin, 5-15 wt% chlorinated polyolefin resin, 1-3 wt% polyester resin, 30-40 wt% pigment, 15-25 wt% solvent, additive 1- A main body comprising 3% by weight and 1-3% by weight of a curing catalyst; And A coating composition comprising a curing agent portion comprising a polyisocyanate, wherein the weight ratio of the curing agent portion to the main portion is from 100: 1 to 10. The coating composition according to claim 1, wherein the polychlorinated polyolefin modified acrylic resin has a hydroxyl value of 15-45 mgKOH, a molecular weight of 40000-100000, and a solid content of 35-65%. The chlorinated polyolefin-modified acrylic resin according to claim 2, wherein the chlorinated polyolefin-modified acrylic resin has a molecular weight of 40000-60000, a solid content of 40-50%, and a hydroxyl value of 25-35 mgKOH. A coating composition, characterized in that the mixture is a mixture of a chlorinated polyolefin-modified acrylic resin (B) having a molecular weight, a solid content of 30-50% and a hydroxyl value of 10-30 mgKOH. The method of claim 1. The coated polyolefin resin has a solid content of 10-40% and a molecular weight of 50000-100000. The method of claim 1, wherein the curing catalyst is one or more selected from the group consisting of 0.01 to 1% by weight of tetramethylbutanediamine, bicyclooctane, dibutyltin dilaurate, triethylenediamine, zinc octoate and calcium octoate Coating composition characterized by the above-mentioned. The coating composition according to claim 1, wherein the curing agent is a diluent of polyisocyanate selected from hexamethylene diisocyanate, xylene diisocyanate and isophorone diisocyanate.