KR20110116691A - Chlorine-free primer coating composition for automotive parts - Google Patents

Abstract

The present invention relates to a non-chlorinated primer coating composition for automobile parts, and more particularly, using a mixture of non-chlorinated polyolefins, without affecting the compatibility with other components, and excellent coating properties, water resistance, high-pressure car wash The present invention relates to a primer coating composition for automobile parts that can be formed, is environmentally friendly, and can improve the arrival efficiency of the colored top coat and the transparent paint which are subsequently coated.

Description

Chlorine-free primer coating composition for automotive parts

The present invention relates to a non-chlorinated primer coating composition for automobile parts, and more particularly, using a mixture of non-chlorinated polyolefins, without affecting the compatibility with other components, and excellent coating properties, water resistance, high-pressure car wash The present invention relates to a primer coating composition for automobile parts that can be formed, is environmentally friendly, and can improve the arrival efficiency of the colored top coat and the transparent paint which are subsequently coated.

As most automotive exterior materials including bumpers, molded articles of polyolefin such as polyethylene and polypropylene are frequently used in place of metal molded articles in order to meet market requirements such as price, performance and recycling. However, these polyolefin materials have non-polarity and low surface tension characteristics, and are generally difficult to paint or adhere. Therefore, in the case of coating the coating on these molded articles, in order to improve the adhesion between the top coat and the molded article, a primer containing a chlorinated polyolefin with polarity is usually applied in advance.

In the polyolefin primer, the use of chlorinated polyolefin is considered essential from the viewpoint of compatibility with other components in the primer, adhesion of the formed coating film, etc., but from the viewpoint of environmental protection, the development of non-chlorinated primers containing no chlorine is strongly recommended. It is required. Chlorine is highly reactive due to the nature of the element and contains organic matter (PVC, disinfectant or disinfectant) or inorganic matter. Chlorine in the coating material is not only subject to environmental regulation but also to users, producers and the environment. Since it adversely affects, the development of dechlorination technology is urgently required.

In addition, recently, due to physical properties and cost, the rubber components (styrene butadiene rubber, isoprene rubber, etc.) or hydroxyl group-containing polyolefins that have been added to polyolefin molded products have been reduced or even not added at all. The problem that the adhesiveness with the existing primer containing this is degraded arises.

In order to solve this problem, Japanese Laid-Open Patent Publication No. 2002-121462 proposes a primer containing a specific chlorinated polyolefin and a specific block polyisocyanate together with a polyol resin. However, this technique also requires the use of chlorinated polyolefins, and still suffers from the chlorine problem described above.

Japanese Laid-Open Patent Publication No. 2002-121462

The present invention is to solve the problems of the prior art as described above, while using a mixture of non-chlorinated polyolefins without affecting the compatibility with other components, to form a coating film excellent in adhesion, water resistance, high-pressure car wash resistance, etc. It is a technical problem to provide a primer coating composition for automobile parts, in particular for automobile bumpers, which is environmentally friendly and can improve the arrival efficiency of subsequent colored topcoats and transparent paints.

The present invention to solve the above technical problem, (A) low molecular weight non-chlorinated polyolefin having a weight average molecular weight of 40,000 ~ 60,000, (B) high molecular weight non-chlorinated polyolefin having a weight average molecular weight of 60,000 ~ 100,000 or less, (C) A non-chlorinated primer coating composition comprising an acrylic resin, (D) a conductive pigment and (E) an organic solvent, wherein the content of the high molecular weight non-chlorinated polyolefin is greater than or equal to the low molecular weight non-chlorinated polyolefin. to provide.

On the other hand, according to another aspect of the present invention, there is provided an automobile part, preferably an automobile bumper, which has a primer coating layer formed by applying the non-chlorinated paint composition of the present invention on its surface.

According to the present invention, it is possible to form a coating film excellent in adhesion, water resistance, high-pressure car wash, etc., and is environmentally friendly, and can improve the arrival efficiency of the colored top coat and the transparent paint that are subsequently coated, and thus, especially for automobile parts A primer coating composition suitable for the purpose can be obtained.

1 is a view schematically showing an example of a multilayer coating structure in which a coating layer of a primer coating composition is formed on a substrate (polypropylene-based plastic material), and a base coat and a clear coat are sequentially formed thereon.

Hereinafter, the primer coating composition of the present invention will be described in detail.

(A) and (B) Dechlorination Polyolefin

In order to fundamentally prevent problems such as corrosion of metal pigments, environmental pollution and adverse effects on the human body in the existing chlorinated polyolefin resin, in the primer coating composition of the present invention, low molecular weight non-chlorinated polyolefin (A) and high A molecular weight non-chlorinated polyolefin (B) is used in combination. Such a combination of low molecular weight and high molecular weight non-chlorinated polyolefins is particularly effective in enhancing the adhesion performance of a primer to a bumper based on polypropylene.

As such a non-chlorinated polyolefin resin, a resin obtained by (co) polymerizing an unsaturated olefin monomer having 3 to 8 carbon atoms may be used. Preferably, a propylene monomer is used to increase the adhesion performance of a primer to a bumper containing polypropylene as a main component. Resin obtained as a main component and copolymerized with other monomers is used. The resin in which propylene and other monomers are copolymerized is preferable because it can lower the crystallinity compared to the propylene homopolymer, increase the solubility and increase the adhesion to the substrate by using propylene as the main component. In the case of such a propylene copolymer resin, crystallinity and solubility can be controlled by controlling other monomer contents.

Examples of such non-chlorinated polyolefin resins include polypropylene-polyethylene copolymer resins, polypropylene-polystyrene copolymer resins, and the like.

In the composition of this invention, such a non-chlorinated polyolefin resin is divided and used for each molecular weight. That is, in the present invention, (A) a low molecular weight non-chlorinated polyolefin having a weight average molecular weight of 40,000 or more and less than 60,000 and (B) a high molecular weight non-chlorinated polyolefin having a weight average molecular weight of 60,000 or more and 100,000 or less, together, the high molecular weight non-chlorinated It is characterized in that the content of the polyolefin is greater than or equal to the low molecular weight non-chlorinated polyolefin. The preferred average solids content of the low molecular weight non-chlorinated polyolefin (A) is 13 to 17% by weight, and the preferred average solids content of high molecular weight non-chlorinated polyolefin (B) is 18 to 22% by weight.

In the coating composition of the present invention, the low molecular weight non-chlorinated polyolefin (A) is preferably contained in an amount of 10 to 20% by weight, more preferably 12 to 15% by weight, based on 100% by weight of the total composition. If the content is less than 10% by weight, the pigment dispersibility may deteriorate, and if it exceeds 20% by weight, the coating film adhesion may be lowered. Moreover, the weight average molecular weights of low molecular weight non-chlorinated polyolefin (A) are 40,000 or more and less than 60,000, More preferably, they are 45,000 or more and 55,000 or less. When this weight average molecular weight is less than 40,000, pigment dispersibility deteriorates.

On the other hand, the coating composition of the present invention is preferably contained 15 to 30% by weight, more preferably 15 to 25% by weight based on 100% by weight of the total amount of the non-chlorinated polyolefin (B) composition. If the content is less than 15% by weight, the coating film adhesion may be lowered. If the content is more than 30% by weight, the composition may have a high viscosity and may be difficult to work with. The weight average molecular weight of the high molecular weight non-chlorinated polyolefin (B) is 60,000 or more and 100,000 or less, and more preferably 60,000 or more and 80,000 or less. When this weight average molecular weight exceeds 100,000, atomization will fall remarkably and spray will be difficult.

(C) acrylic resin

The acrylic resin component included in the non-chlorinated primer composition of the present invention is used for high-pressure car wash reinforcement, securing interlayer adhesion after water resistance, and improving the appearance of the coating film. The acrylic resin preferably has a solid content of 40 to 60% and is compatible with other components in the paint, in particular, non-chlorinated polyolefin resin. The coating composition of the present invention preferably contains 2 to 7% by weight of the acrylic resin (C) based on 100% by weight of the total composition. If the acrylic resin content is less than 2% by weight, the coating film hardness is weakened, and the high-pressure car wash property is easily lowered. If the acrylic resin content is more than 7% by weight, the adhesion to the substrate can be reduced.

(D) conductive pigment

The electroconductive pigment (D) contained in the non-chlorinated primer composition of this invention is used in order to electrostatically coat the composition of this invention to a plastic material, and to electrostatically coat the following top coat on it. If electroconductivity can be provided to the coating film formed, there will be no restriction | limiting in particular in electroconductive pigment, Any shape, such as particle shape, a flake shape, a fiber shape, may be sufficient. For example, carbon powder, such as electroconductive carbon black, and metal powder, such as silver, nickel, steel, graphite, aluminum, etc. can be used. In addition, tin oxide coated with antimony, tin oxide doped with phosphorus, antimony oxide, titanium oxide, coated with tin oxide or the like on a whisker surface of carbon or graphite, or tin oxide or nickel coated on a flake-shaped mica surface It can also be used. These can be used individually or in combination of 2 or more types, respectively, It is preferable to use electroconductive carbon black among these especially from an economic viewpoint. In the coating composition of the present invention, the conductive pigment (D) is preferably contained 1 to 3% by weight based on 100% by weight of the total composition. If the content of the conductive pigment is less than 1% by weight, there may be a lack of securing the conductivity required for electrostatic coating. If the content of the conductive pigment is more than 3% by weight, adhesion failure of the coating film may be caused.

In addition to the conductive pigments, color pigments, extender pigments and the like may be further used as necessary. Examples of the coloring pigment include titanium dioxide, aluminum paste, azo type, phthalocyanine type and the like, and examples of the extender pigment include talc, silica, calcium carbonate, barium sulfate, zinc oxide and the like. These pigment components can also be used individually or in combination of 2 or more types, respectively.

(E) solvent

As a solvent component (E) contained in the non-chlorinated primer composition of this invention, the normal solvent used for a coating composition can be used, Preferably an aromatic hydrocarbon can be used. The aromatic hydrocarbon solvent includes toluene, xylene, cocosol or mixtures thereof. The coating composition of the present invention preferably contains 10 to 50% by weight, more preferably 15 to 45% by weight, based on 100% by weight of the total composition of the solvent component (E). If the solvent content is less than 10% by weight may result in a defect that the appearance is poor when forming the coating film, when the content exceeds 50% by weight can not only lower the solid content of the paint but also to lower the viscosity of the paint to accelerate the pigment settling.

(F) other additives

In addition to the above components, the non-chlorinated primer composition of the present invention, if necessary, additives such as a wetting dispersant which improves dispersibility and enhances the stability of the paint and prevents sedimentation of the pigment and adjusts the rheology of the paint. It may further include.

Wetting dispersant and anti-settling agent are added together with the pigment in the dispersing process, which is the manufacturing process of the paint, to stabilize the pigment in the final paint and to prevent the sedimentation of the pigment during the storage period, as well as to impart rheology to the paint to make the coating process and coating after painting Stability can be imparted. In the present invention, a known general dispersant may be used, and preferably, a polymer dispersant having a weight average molecular weight of 5000 to 30000 having a polyurethane or polyacrylate structure may be used. The sedimentation inhibitor may also use a known general sedimentation inhibitor, preferably a modified hectorite-based sedimentation inhibitor. In particular, when fumed silica is used together in the dispersing process, it is possible to prevent the settling of the pigment and impart thixotropy to the paint. These additives may be added independently about 0.1 to 3 parts by weight per 100 parts by weight of the coating composition, but is not limited thereto.

The non-chlorinated primer coating composition of the present invention can be prepared according to a conventional coating composition production method by using the components as described above in the content as described above. According to one embodiment of the present invention, after the pigment dispersion is carried out according to a separate process, the dispersed pigment components are mixed with a non-chlorinated polyolefin resin, an acrylic resin, a solvent, and the like, stirred sufficiently, and then filtered, and then chlorinated. A primer coating composition can be obtained. In the separate pigment dispersion process, for example, a polyurethane dispersant in the form of a polyurethane is added to xylene as an aromatic solvent to wet the pigment, a non-chlorinated polyolefin resin is added and sufficiently stirred, and then a dispersing bead is added thereto. And disperse in a disperser. The criterion of completion of dispersion may be based on the particle size (eg, 10 μm or less) of the pigment.

The coating composition of the present invention thus obtained is suitable for automobile parts, particularly bumpers, of plastic material. Therefore, according to another aspect of the present invention, there is provided an automobile part, preferably an automobile bumper, which has a primer coating layer formed by applying the coating composition of the present invention on its surface.

There is no particular limitation on the coating method of the coating composition, and a conventional coating composition coating method (for example, spray coating) may be utilized. There is no particular limitation on the coating thickness, and for example, the coating may be coated with a thickness of about 5 to 10 μm. After the primer coating, the colored basecoat paint and the clearcoat are sequentially electrostatically coated on them, if necessary, followed by heat drying.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, these examples are only to aid the understanding of the present invention, and the present invention is not limited thereto.

Example  1-4 and Comparative example  1-2

Preparation of Paint Composition

To the coating composition was prepared in a composition as shown in Table 1 below. Here, the pigment dispersing process was carried out separately. Specifically, xylene was added as an aromatic solvent to a 1L tin can, and a polymer dispersant in the form of a polyurethane was added thereto to wet the pigment, and a non-chlorinated modified polyolefin resin was added thereto. Stirred. After stirring, dispersing beads were added 1: 1 (weight ratio) to the mixed solution, followed by dispersion for about 1 hour in a red devil. Dispersion was terminated when the particle size of the pigment is less than 10㎛, wherein the particle size of the pigment was measured using a particle size meter of Sheen.

The components of the composition shown in Table 1 were added to the dispersed pigment mill base thus prepared, and the mixture was sufficiently stirred for 30 minutes or more. After the preparation of the composition was completed, the filter was used as a primer for the bumper.

Table 1. Non-chlorinated primer composition formula (unit: parts by weight)

Polyolefin resin 1: weight average molecular weight about 50,000, average solids about 15%, non-chlorinated

Wetting Dispersant: Polymeric dispersant with molecular weight of 5000-30000 with polyurethane structure

(BYK-163: Examples 1-3 and Comparative Examples 1-2; EFKA-4015: Example 4)

Antisettling Agent: Aerosil Fumed Silica

Conductive Pigment: Conductive Carbon Black

Polyolefin resin 2: weight average molecular weight about 75,000, average solids about 20%, non-chlorinated

Acrylic resin: about 50% average solids, Tg = 50 degreeC, viscosity Y-Z1

Evaluation of Physical Properties of Prepared Coating Composition

The paint compositions prepared in Examples and Comparative Examples were applied as primers for automobile bumpers (material: EMPP) to evaluate physical properties.

The primer prepared in Table 1 was spray-coated onto a polypropylene molded with a bumper so as to have a dry coating thickness of about 5 to 10 μm, and after setting at room temperature for 5 to 10 minutes, UT5731 (manufactured by KCC) was used as a coloring base coat paint thereon. , Oil-based base coat paint) to electrostatic coating to dry film thickness of about 15-20㎛, and after setting at room temperature for 5-10 minutes, UT595-CLEAR (KCC, acrylic urethane solvent clear paint) as dry paint The electrostatic coating was made to be about 30 micrometers in thickness, and it heat-dried at 80 degreeC for 30 minutes, and produced the test coating material. The physical properties of the items shown in Table 2 were evaluated for the prepared coating specimens, and the results are shown in Table 2 below. The specific performance test method was as follows.

Performance test  Way

(1) Appearance: The projections and gloss of the coating film surface were visually evaluated. (Circle) shows that an external appearance is favorable, and x shows that abnormality of a processus | protrusion or glossiness was confirmed even if it is one point.

(2) Electrical resistance: The primer was spray-coated to a thickness of about 5 to 10 μm as a dry film thickness, and heated and dried at 60 ° C. for 10 minutes, and measured by a Lansberg resistance test instrument. , × indicates that the standard is out of specification.

(3) Initial adhesiveness: A perforation line is made with a cutter to reach the base on the coating film, 100 squares of 2 mm x 2 mm are made, adhered to the surface by adhesive cellophane tape, and rapidly peeled off at 20 ° C. The number of remaining coating films of the square was evaluated.

(4) Impact resistance: The weight of 1 kg was dropped into the coating film at a height of 50 cm with a DuPont impactor, and the state of the coating film was measured.

(5) Flexibility: A coating film test piece of constant size (25 × 1500 mm) was bent 180 ° around a 13 mm diameter round bar to measure the state of the coating film. (Circle) shows that a crack and a crack exist in a coating film, and x shows that a crack and a crack were confirmed even if it is one point.

(6) Water Resistance Adhesion: A part of the coated bumper was cut out, immersed in warm water at 40 ° C. for 10 days, taken out and dried, and then subjected to an adhesion test, and the coated surface was visually evaluated. ○ indicates no blister generation, and × indicates blister generation.

(7) High pressure car washability: The coating test piece was evaluated by confirming the degree of peeling of the coating film after spraying with a commercial high pressure car wash (at least 8500 kPa for 5 seconds in a nozzle gun having a gun tip angle of 15 ° or 25 °).

Table 2. Property Evaluation Results

Claims (7)

(A) low molecular weight non-chlorinated polyolefins having a weight average molecular weight of 40,000 to less than 60,000, (B) high molecular weight non-chlorinated polyolefins having a weight average molecular weight of 60,000 to 100,000 or less, (C) acrylic resins, (D) conductive pigments, and (E A non-chlorinated primer coating composition comprising an organic solvent, wherein the content of said high molecular weight non-chlorinated polyolefin is equal to or greater than said low molecular weight non-chlorinated polyolefin.
The non-chlorinated primer coating composition according to claim 1, wherein the low molecular weight non-chlorinated polyolefin (A) is contained in an amount of 10 to 20% by weight based on 100% by weight of the total composition.
The non-chlorinated primer coating composition according to claim 1, wherein the high molecular weight non-chlorinated polyolefin (B) is contained in an amount of 15 to 30% by weight based on 100% by weight of the total composition.
The non-chlorinated primer coating composition according to claim 1, wherein the acrylic resin (C) is contained in an amount of 2 to 7% by weight based on 100% by weight of the total composition.
The non-chlorinated primer coating composition according to claim 1, wherein the conductive pigment (D) is conductive carbon black.
An automotive part having a primer coating layer formed on the surface thereof by applying the non-chlorinated primer coating composition according to any one of claims 1 to 5.
The vehicle part according to claim 6, which is an automobile bumper.

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