KR20100023654A - Styrenic resin composition with paintability and good impact resistance - Google Patents

Abstract

PURPOSE: A styrenic resin composition is provided to ensure excellent paintability and impact resistance, to be broadly applied in the molding of various products, especially materials for motorcycle requiring relatively little demands of heat resistance. CONSTITUTION: A styrenic resin composition comprises (A) 20-40 weight% of styrenic graft resin graft-polymerized with a rubber polymer of which average particle size is 0.25-0.4 micron; and (B) 60-80 weight% of vinyl cyanide compound-aromatic vinyl compound copolymer which has 60,000-100,000 of average molecular weight and contains 30-45 weight% of vinyl cyanide compound. The styrenic graft resin is prepared by performing emulsion graft polymerization of a vinyl cyanide compound and an aromatic vinyl compound in the presence of a rubbery polymer.

Description

Styrene-based resin composition excellent in paintability and impact resistance {STYRENIC RESIN COMPOSITION WITH PAINTABILITY AND GOOD IMPACT RESISTANCE}

The present invention relates to a styrene resin composition, and more particularly to a styrene resin composition excellent in paintability and impact resistance.

Acrylonitrile-butadiene-styrene copolymer resin (hereinafter referred to as 'ABS resin') is prepared by graft polymerization of an styrene monomer, an aromatic vinyl compound, and an acrylonitrile monomer, an unsaturated nitrile compound, in the presence of a butadiene rubbery polymer. . Butadiene-based rubbery polymers impart flexibility and impact resistance, and styrene monomers and acrylonitrile monomers provide excellent processability and chemical resistance, respectively. Accordingly, acrylonitrile-butadiene-styrene copolymer resins have been widely used for various purposes by adjusting the respective contents according to the purpose, and the range is gradually expanded for coating of automobiles, motorcycles, and the like.

As the use of ABS resins for painting is expanded, the types of solvents used for painting are also diversified. However, when the coating process is performed with a solvent with strong solvent properties, the rubber component deformed by the stress during injection swells and the solvent is absorbed unevenly into the resin, resulting in irregularities on the surface of the resin and irregular pigments. There is a problem that the coating properties are rapidly deteriorated.

Therefore, lubricants are introduced as additives as a method for solving the above problems during coating. However, it may lead to peeling of the molded product according to the use of the lubricant, and also to reduce the weld strength. In addition, when a small amount of the crystalline polymer is used to increase the chemical resistance of the resin by the solvent, the adhesion of the coating is reduced.

The present invention is to solve the above problems, and to optimize the graft copolymer prepared by the emulsion polymerization method in the presence of a rubbery polymer having an optimized particle size, and a vinyl copolymer having an optimized weight average molecular weight It is intended to provide a styrene resin composition excellent in paintability and impact resistance by using in the content range.

The present invention also provides a molded article produced using the styrene resin composition.

However, technical problems to be achieved by the present invention are not limited to the above-mentioned problems, and other technical problems will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, according to one embodiment of the present invention (A) 20 to 40% by weight of a styrenic graft resin graft polymerized rubbery polymer having an average particle size of 0.25 to 0.4 ㎛; And (B) 60 to 80 wt% of a copolymer of a vinyl cyanide compound-aromatic vinyl compound having a weight average molecular weight of 60,000 or more and less than 100,000 and containing 30 to 45 wt% of a vinyl cyanide compound in the polymer. To provide.

According to another embodiment of the present invention provides a molded article manufactured using the styrene-based resin composition.

Other specific details of embodiments of the present invention are included in the following detailed description.

Styrene-based resin composition according to the present invention has excellent paintability and impact resistance can be widely applied to the molding of various products requiring impact resistance and paintability, and particularly useful for motorcycle materials having a low heat resistance requirement Can be used.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The present invention relates to a styrenic resin composition excellent in paintability and impact resistance, the styrene resin composition according to an embodiment of the present invention (A) graft polymerized rubbery polymer having an average particle size of 0.25 to 0.4 ㎛ 20 to 40% by weight of styrenic graft resin; And (B) 60 to 80 wt% of a copolymer of a vinyl cyanide compound-aromatic vinyl compound having a weight average molecular weight of 60,000 or more and less than 100,000 and containing 30 to 45 wt% of a vinyl cyanide compound in the polymer.

Hereinafter, each component included in the styrene-based resin composition according to one embodiment of the present invention will be described in detail.

(A) styrene Graft resin

The styrene graft resin may be prepared by emulsion graft polymerization of a monomer mixture of a vinyl cyanide compound and an aromatic vinyl compound in the presence of a rubbery polymer.

As the rubbery polymer, polybutadiene may be used, but is not necessarily limited thereto. Acrylic rubber, ethylene / propylene rubber, styrene / butadiene rubber, acrylonitrile / butadiene rubber, isoprene rubber, ethylene-propylene-diene terpolymer (EPDM), polyorganosiloxane / polyalkylmethacrylate rubber composites, and mixtures thereof can be used.

In addition, the rubbery polymer preferably has an average particle size of 0.25 to 0.4 m. When the average particle size of the rubbery polymer is less than 0.25 μm, impact strength and environmental stress resistance may be reduced, and when it exceeds 0.4 μm, rubber production time may be lengthened and gloss may be reduced.

Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, C ₁ -C ₈ methacrylic acid alkyl esters, C ₁ -C ₈ acrylic acid alkyl esters, maleic anhydride, C ₁ -C ₄ alkyl or phenyl nucleation. Maleimide or mixtures thereof can be used.

As the aromatic vinyl compound, styrene, α-methylstyrene, halogen or alkyl substituted styrene, C ₁ -C ₈ methacrylic acid alkyl esters, C ₁ -C ₈ acrylic acid alkyl esters or mixtures thereof may be used.

The rubbery polymer during the emulsion graft polymerization is preferably used in 40 to 70% by weight. Impact resistance is preferred when used in the above content range.

In addition, the ratio of the monomer mixture of the vinyl cyanide compound and the aromatic vinyl compound and the selection of the monomer may be easily carried out by those skilled in the art. The mixture of the vinyl cyanide compound and the monomer of the aromatic vinyl compound is preferably used in an amount of 60 to 30% by weight, and the vinyl cyanide compound and the aromatic vinyl compound are preferably mixed in a weight ratio of 20:80 to 30:70.

Styrene-based graft resin prepared by the above method is preferably included in 20 to 40% by weight, more preferably 25 to 35% by weight based on the total weight of the styrene-based resin composition. When the content of the styrenic graft resin is in the above range, it is preferable in view of the balance of physical properties of paintability and impact resistance.

(B) Vinyl Cyanide Compound-Aromatic Vinyl Compound Copolymer

The vinyl cyanide compound-aromatic vinyl compound copolymer is a vinyl copolymer having a weight average molecular weight of 60,000 or more but less than 100,000, preferably 70,000 to 90,000. When the weight average molecular weight of the vinyl cyanide compound-aromatic vinyl compound copolymer is less than 60,000, impact resistance may decrease, and when 100,000 or more, paintability may decrease.

Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, C ₁ -C ₈ methacrylic acid alkyl esters, C ₁ -C ₈ acrylic acid alkyl esters, maleic anhydride, C ₁ -C ₄ alkyl or phenyl nucleation. Maleimide or mixtures thereof can be used.

As the aromatic vinyl compound, styrene, α-methylstyrene, halogen or alkyl substituted styrene, C ₁ -C ₈ methacrylic acid alkyl esters, C ₁ -C ₈ acrylic acid alkyl esters or mixtures thereof may be used.

The vinyl cyanide compound-aromatic vinyl compound copolymer preferably further contains 30 to 45 wt% of the vinyl cyanide compound in the copolymer. When the vinyl cyanide compound is less than 30% by weight, the impact resistance may be lowered. When the vinyl cyanide compound is less than 45% by weight, the melt viscosity may be high, thereby decreasing workability.

The vinyl cyanide compound-aromatic vinyl compound copolymer as described above is preferably included in 60 to 80% by weight, more preferably 65 to 75% by weight relative to the total weight of the styrene-based resin composition. If the content of the vinyl cyanide compound-aromatic vinyl compound copolymer is less than 60% by weight, the fluidity may be lowered, thereby lowering productivity due to overload during extrusion, deteriorating the hardness of the product and causing discoloration during high temperature processing. If it exceeds 80% by weight, excellent paintability and appropriate impact strength are difficult to obtain.

(C) other additives

The styrene resin composition may further include other additives such as dyes, pigments, antioxidants, lubricants, impact modifiers, etc., according to necessity and purpose without departing from the object of the present invention. At this time, the additive may be included alone or in a mixture of two or more, the content thereof may be used in the range of 0.1 to 30 parts by weight based on 100 parts by weight of the total styrene-based resin composition.

The styrene-based resin composition having the composition as described above may be prepared by a known method for preparing a resin composition, for example, the components and other additives are mixed at the same time, and then melt-extruded in an extruder to form pellets. can do.

The composition has a measured value of gloss 20 ° of 55 or more as measured by a gloss meter. In addition, the composition has an Rt value of 5.5 or less when measured at 6 times magnification surface roughness using an optical profiler NT2000 (Veeco) for evaluation of coating properties. In a specific example, the measured value of gloss 20 ° is 55 to 80, and the Rt value is 2 to 5.5.

Styrene-based resin composition according to the invention can be used in the molding of a variety of products that require impact resistance and paintability having excellent paintability and impact resistance, in particular can be applied to a wide range of motorcycle materials, such as less demanding heat resistance Do.

Hereinafter, the present invention will be described in more detail with reference to Examples, but these Examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example

The specifications of (A) g-ABS resin and (B) vinyl cyanide compound-aromatic vinyl compound copolymer used in the following examples and comparative examples are as follows.

(A) styrene Graft resin

(a1) A g-acrylonitrile butadiene styrene copolymer (g-ABS) resin having a core-shell form was used by emulsion graft polymerization of a rubbery polymer having an average rubber particle diameter of 0.31 μm.

(a2) The rubbery polymer having an average rubber particle diameter of 0.13 mu m was subjected to emulsion graft polymerization to use a g-ABS resin having a core-shell form.

(B) Vinyl Cyanide Compound-Aromatic Vinyl Compound Copolymer

(b1) Styrene Acrylonitrile Copolymers (SAN) resin having an acrylonitrile content of 35% by weight and a weight average molecular weight of 80,000 was used.

(b2) A SAN resin having an acrylonitrile content of 24.5 wt% and a weight average molecular weight of 90,000 was used.

(b3) A SAN resin having an acrylonitrile content of 32% by weight and a weight average molecular weight of 130,000 was used.

Example  1, 2 and Comparative example  1 to 4

Each of the components was added in an amount as shown in Table 1, followed by melting and kneading extrusion to prepare pellets. The extrusion was a twin screw extruder L / D = 29, 40 mm in diameter and the cylinder temperature was set to 220 ℃.

TABLE 1

Example (% by weight) Comparative Example (wt%) One 2 One 2 3 4 A (a1) 25 35 10 - 30 30 (a2) - - - 30 - - B (b1) 75 65 90 70 - - (b2) - - - - 70 - (b3) - - - - - 70

[Physical Evaluation Test]

Physical properties of the prepared pellets were injection molded to measure paintability and Izod impact strength. The results are shown in Table 2.

1) Paintability: 50mm × 200mm × 2mm specimens injected into the pin gate were spray-coated at a pressure of 3 to 5kgf / cm ² using a two-component urethane paint (manufactured by Aekyung P & C). Sprayed PBC # 2000 AK-2300 silvered with plate-shaped aluminum flakes and dried at 60 ° C. for at least 5 minutes, sprayed AKU CLEAR #A on top and dried at 60-70 ° C. for at least 40 minutes.

The paintability evaluation was performed by the following method.

① Gloss measurement : Gloss was measured by ASTM D-523 measuring method. When the gloss meter is measured, the incident light is scattered and reflected depending on the state of the surface, so the surface smoothness of the measured specimen can be seen. In the measurement, since the reflection angle is largely measured by the top coat and the discrimination power may be lowered after the treatment to the top coat, the measurement was performed after treating only a diluent (PBC # 2000 MP100: manufactured by MEK Co., Ltd.) which has a decisive effect on paintability. If the surface of the injection molded specimen is eroded irregularly by the diluent, the measured value is small, and if it is evenly eroded, the measured value is large. The measurement results are shown in Table 2 below.

② Surface Observation : The surface of the coated specimen was observed using the resin composition of Example 1 and Comparative Examples 1 and 3 at 100 times magnification using an optical microscope. The results are shown in FIGS. 1A-1C.

FIG. 1A is an optical microscope 100 times observation photograph of a coated specimen coated using the resin composition according to Example 1 of the present invention, and FIG. 1B is an optical image of the coated specimen coated using the resin composition according to Comparative Example 1. 100 times the observation photograph of the microscope, Figure 1c is an optical microscope 100 times observation photograph of the coated specimen coated using the resin composition according to Comparative Example 3.

③ Surface roughness measurement : 6x magnification surface roughness was measured in VSI mode using optical profiler NT2000 (Veeco). As with the Gloss measurement, the surface smoothness can be determined, and among the measured values, the Rt value can be assessed by the diluent with the difference between the highest point and the lowest point and how evenly eroded the specimen of the injection molded product is. The measurement results are shown in Table 2 below.

④ Visual judgment : The paintability was evaluated by visual evaluation of the painted specimens by the 3-point standard method as follows. The measurement results are shown in Table 2 below.

X: The coating erosion is severe and cannot be used.

(Triangle | delta): When painting erosion is seen partially

○: When there is no coating erosion.

In addition, photographic images of the coated specimens coated with the resin compositions of Example 1 and Comparative Examples 1 and 3 were photographed. The results are shown in Figures 2a to 2c.

FIG. 2A is an observation photograph of a coated specimen coated using a resin composition according to Example 1 of the present invention, and FIG. 2B is an observation photograph of a coated specimen coated using a resin composition according to Comparative Example 1, FIG. 2c is an observation photograph of the coated specimen coated using the resin composition according to Comparative Example 3.

2) Izod impact strength: Izod impact strength (1/4 ", kgf · cm / cm) was measured according to ASTM D-256. The measurement results are shown in Table 2 below.

TABLE 2

Example Comparative example One 2 One 2 3 4 Dojang Castle Gloss 20 ° 63 67 31 36 49 33 Surface roughness 4.9 5.0 9.5 8.9 7.3 9.1 Visual judgment ○ ○ X X △ X Izod impact strength (1/4 ", kgfcm / cm) 32 38 16 13 32 35

As shown in Table 2, the styrene-based graft resin comprising a styrenic graft resin (a1) using less than the content range of the present invention, and a rubbery polymer having an average rubber particle diameter outside the range of the present invention. In the case of Comparative Example 2 using (a2), it can be confirmed that the physical property balance of the desirable coating properties and impact resistance cannot be obtained.

In addition, in the copolymer (B) of the vinyl cyanide compound-aromatic vinyl compound, the weight average of the comparative example 3 using the vinyl cyanide compound (b2) whose acrylonitrile content is less than 30 weight%, and the vinyl cyanide compound-aromatic vinyl compound copolymer Comparative Example 4 using the vinyl cyanide compound-aromatic vinyl compound copolymer (b3) whose molecular weight is outside the scope of the present invention can also confirm that excellent paintability cannot be obtained.

In addition, as shown in Figure 1a to 1c, the optical microscope observation results of the coating specimens coated with the resin compositions of Example 1, Comparative Examples 1 and 3, the surface of the specimen coated by the resin composition according to Example 1 is a pigment While the aluminum flakes (Al flake) used as is uniformly arranged, the coating specimens coated with the resin compositions of Comparative Examples 1 and 3 was uneven surface, the aluminum flakes were not evenly spread.

As shown in FIGS. 2A to 2C, coating surface observations of the coating specimens coated with the resin compositions of Examples 1 and Comparative Examples 1 and 3 showed that the surface of the specimens coated with the resin composition according to Example 1 was coated with erosion. On the other hand, coating specimens coated with the resin compositions of Comparative Examples 1 and 3 were found to be coated erosion, especially in Comparative Example 1 using styrene-based graft resin (a1) below the content range of the present invention. Erosion was found throughout.

From these results, the styrene resin composition prepared according to the method of the present invention is a copolymer of a styrenic graft resin having a rubbery polymer having a specific range of sizes with a specific vinyl cyanide compound-aromatic vinyl compound having a vinyl cyanide content and molecular weight. By using a sieve, excellent coating properties and impact resistance can be exhibited at the same time.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

1A to 1C are photographs of optical microscopes 100 times of coated specimens of Example 1, Comparative Example 1, and Comparative Example 3 of the present invention, respectively.

2A to 2C are photographs of coating specimens of Example 1, Comparative Example 1, and Comparative Example 3 of the present invention, respectively.

Claims (6)

(A) 20 to 40% by weight of a styrenic graft resin obtained by graft polymerization of a rubbery polymer having an average particle size of 0.25 to 0.4 m; And (B) 60 to 80 wt% of a vinyl cyanide compound-aromatic vinyl compound copolymer having a weight average molecular weight of 60,000 or more and less than 100,000 and containing 30 to 45 wt% of a vinyl cyanide compound in the polymer Styrene-based resin composition comprising a. The method of claim 1, The vinyl cyanide compound-aromatic vinyl compound copolymer has a weight average molecular weight of 70,000 to 90,000. The method of claim 1, The styrene-based graft resin is a styrene resin composition prepared by emulsion graft polymerization of a monomer mixture of a vinyl cyanide compound and an aromatic vinyl compound in the presence of a rubbery polymer. The method of claim 1, Said composition is a styrene resin composition having a measured value of gloss 20 ° measured by a gloss meter of 55 or more. The method of claim 1, The composition is a styrene-based resin composition having an Rt value of 5.5 or less when measured 6 times magnification surface roughness using an optical profiler NT2000 (Veeco) for the evaluation of coating properties. A molded article prepared from the styrene resin composition according to any one of claims 1 to 5.

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