KR100884613B1 - Thermoplastic Resin Composition Having Excellent Thermal-Conductivity - Google Patents

Abstract

The present invention relates to a thermally conductive thermoplastic resin composition, and relates to a thermally conductive thermoplastic resin composition in which a graft copolymer, a vinyl cyanide compound-aromatic vinyl compound copolymer and a specific thermal conductive additive are blended in an appropriate ratio to improve thermal conductivity. The thermally conductive thermoplastic resin composition of the present invention may replace aluminum as an incase material of a kimchi refrigerator and may be applied to a dispenser portion and a lamp contact portion of a double door refrigerator.

ABS resin, low melting point metal, ceramic fiber, thermal conductivity

Description

Thermoplastic Resin Composition Having Excellent Thermal-Conductivity

Field of invention

The present invention relates to a thermally conductive thermoplastic resin composition. More specifically, the present invention relates to a thermally conductive thermoplastic resin composition in which a graft copolymer, a vinyl cyanide compound-aromatic vinyl compound copolymer, and a thermally conductive additive are blended in an appropriate ratio, thereby providing excellent thermal conductivity and various colors.

Background of the Invention

In general, the thermal conductivity of polymers or plastics is very low, such as 0.2 W / mK at room temperature has been frequently used for insulation applications. However, in recent years, thermally conductive plastics having a thermal conductivity of 1.0 W / mK or more have been developed by mixing high thermal conductivity reinforcing materials with commercial thermoplastics used for industrial purposes.

Thermally conductive plastics can be used as an alternative to materials using metals, plastics and ceramics. Advantages of thermally conductive plastics over ordinary plastics include the elimination of hot spots, lower component temperatures, improved device efficiency, reduced component warpage, and extended product life. And, due to the low use temperature, the mechanical strength can be improved. On the other hand, thermally conductive plastics have the advantages of being able to save weight (about 50% of aluminum), free design, low thermal expansion coefficient, excellent chemical resistance, and reduced post-processing compared to metals. .

Based on the above advantages, the thermally conductive resin can be mainly applied to a device requiring heat dissipation. Examples thereof include heat exchangers such as heat exchangers for automobile radiators, heat exchangers for refrigerators, heat exchangers for air conditioners, heat sinks, substrates, housings, and electrical connectors for electrical and electronic products. Another example of heat dissipation is industrial motors, spindle motors for hard disk drives, DVD motors, CD motors, and the like.

On the other hand, in recent years, the application has been tried in kimchi refrigerator in-case (IN-CASE), double door type refrigerator dispenser, lamp area and the like. Metals such as aluminum and copper have been mainly used as heat dissipating materials for these devices. These metals have very high thermal conductivity of 100W / mK or more at room temperature, and are not suitable for refrigerators. Accordingly, there is a need for thermally conductive plastics with adequate thermal conductivity. To this end, the development of a novel thermoplastic resin material for the production of excellent thermally conductive plastics and the study of the proper addition ratio of the thermally conductive additives are required.

On the other hand, in order to impart thermal conductivity to plastics having very low thermal conductivity, it is common to fill a thermally conductive additive. However, there is a problem that the physical properties of the resin is lowered depending on the amount of the thermally conductive additive added. Accordingly, the thermally conductive additives should be appropriately added according to the physical properties required by the product.

Conventionally, many carbon series thermally conductive additives have been used. By the way, carbon is well known as a material excellent in electrical and thermal conductivity, but when added to the resin has been a serious obstacle to the implementation of various colors other than black due to the intrinsic black.

In order to solve the above problems, the present inventors have added a thermally conductive additive in an appropriate ratio to a base resin composed of a graft copolymer and a vinyl cyanide compound-aromatic vinyl compound copolymer, thereby providing excellent thermal conductivity and thermoelectric capable of implementing various colors. It is early to develop a conductive thermoplastic resin composition.

An object of the present invention is to provide a thermoplastic resin composition excellent in thermal conductivity.

Another object of the present invention is to provide a thermally conductive thermoplastic resin composition capable of realizing various colors by excluding carbon black or graphite as a thermally conductive additive.

Still another object of the present invention is to provide a thermally conductive thermoplastic resin composition having excellent balance of physical properties such as impact strength, flowability, and tensile strength.

It is another object of the present invention to provide a thermally conductive thermoplastic resin composition suitable for a heat dissipating material.

Still another object of the present invention is to provide a thermally conductive thermoplastic resin composition that can be applied to refrigerator parts, such as an in-case for kimchi refrigerator (IN-CASE), a double door type refrigerator dispenser, and a lamp part.

The above and other objects of the present invention can be achieved by the present invention described below.

Summary of the Invention

The thermally conductive thermoplastic resin composition of the present invention (A) 20 to 50 parts by weight of the graft copolymer resin; And (B) 50 to 80 parts by weight of a vinyl cyanide compound-aromatic vinyl compound copolymer; It contains 0.1-30 weight part of (C) heat conductive additives with respect to 100 weight part of basic resin which consists of a.

In one embodiment of the present invention, the graft copolymer (A) is a graft polymer of a rubbery polymer, an aromatic vinyl monomer and a vinyl cyanide monomer.

The rubbery polymer preferably has an average rubber particle diameter of 0.25 to 0.4 탆.

In another embodiment of the present invention, the graft copolymer (A) has a graft rate of 40 to 90% by weight.

In an embodiment of the present invention, the vinyl cyanide compound-aromatic vinyl compound copolymer (B) has a weight average molecular weight of 100,000 to 400,000.

In an embodiment of the present invention the thermally conductive additive (C) is selected from the group consisting of low melting point metals, alumina fibers and mixtures thereof.

In the embodiment of the present invention, the low melting point metal is a metal or an alloy having a melting point of 150 to 300 ° C, and preferably a metal or an alloy having a melting point of 190 to 230 ° C. The low melting point metal is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the base resin. It is preferable to use tin and a copper alloy or tin and an aluminum alloy as said alloy.

In an embodiment of the present invention, the alumina fiber is used in an amount of 10 to 20 parts by weight based on 100 parts by weight of the base resin.

The resin composition of the present invention may further include additives such as antioxidants, lubricants, impact modifiers, flame retardants, heat stabilizers, antioxidants, fillers, inorganic additives, pigments, dyes and the like.

In another embodiment of the present invention, a refrigerator component molded from the resin composition is provided.

Detailed Description of the Invention

(A) graft copolymer resin

The graft copolymer (A) used in the present invention is a graft polymer of a rubbery polymer, an aromatic vinyl monomer of styrene monomer and acrylonitrile, and a vinyl cyanide monomer, respectively.

The rubbery polymer may be a diene rubber such as polybutadiene, poly (styrene-butadiene), poly (acrylonitrile-butadiene), or the like; Saturated rubber hydrogenated to the diene rubber; Isoprene rubber; Alkyl acrylate rubbers; Ethylene-propylene-diene terpolymers (EPDM), ethylene-propylene rubbers and the like can be used, preferably double polybutadiene, poly (styrene-butadiene) rubber. The rubbery polymer may be used alone or in mixture of two or more thereof. In the present invention, the rubbery polymer may be 57 to 62% by weight, preferably 58 to 60% by weight based on 100% by weight of the graft copolymer resin (A). In one embodiment of the present invention, the rubbery polymer preferably has an average rubber particle diameter of 0.25 to 0.4 탆.

The aromatic vinyl monomers include styrene, alpha-methylstyrene, p-t-butylstyrene, 2,4-dimethylstyrene, vinyltoluene, and the like, and styrene monomer or alpha-methylstyrene is preferably used.

Examples of the vinyl cyanide monomer include methacrylonitrile and acrylonitrile, and acrylonitrile is preferably used.

The graft copolymer resin of the present invention may be prepared by a conventional emulsion graft polymerization method by adding the aromatic vinyl monomer and the vinyl cyanide monomer to the rubbery polymer. However, the graft polymerization method is not limited to the emulsion graft polymerization method.

In one embodiment of the present invention, the graft copolymer resin has a graft ratio of 40 to 90% by weight. When the graft ratio is less than 40% by weight, it is difficult to obtain a white powder having a uniform particle size distribution during solidification and drying, as well as fisheye, pinhole or sand as unplasticized particles on the surface of a molded product during extrusion or injection. A phenomenon such as a sand surface may occur and surface glossiness may be lowered. If the graft ratio exceeds 90% by weight, physical properties such as impact strength, fluidity, and surface gloss may be reduced.

In the present invention, the graft copolymer (A) is preferably used in 20 to 50 parts by weight. If the content is less than 20 parts by weight, it is difficult to show the impact resistance more than a predetermined level required by the present invention, and if it exceeds 50 parts by weight, the fluidity may be reduced.

(B) Vinyl Cyanide Compound-Aromatic Vinyl Compound Copolymer

The vinyl cyanide compound-aromatic vinyl compound copolymer (B) of this invention is manufactured by the conventional polymerization method using 20-40 weight% of vinyl cyanide compounds and 60-80 weight% of aromatic vinyl compounds.

The vinyl cyanide compound is not particularly limited, but acrylonitrile, methacrylonitrile, and the like may be used alone or in combination.

The aromatic vinyl compound includes styrene, alpha-methylstyrene, p-t-butylstyrene, 2,4-dimethylstyrene, vinyltoluene, and the like, but is not necessarily limited thereto. The aromatic vinyl compounds may be used alone or in combination.

In addition, these may be copolymerized with N-phenylmaleimide, N-cyclohexyl maleide, maleic anhydride and the like.

The vinyl cyanide compound-aromatic vinyl compound copolymer (B) may be prepared by emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, and the like, and the polymerization method may be prepared by those skilled in the art. It can be easily carried out by a ruler.

In one embodiment of the present invention, the vinyl cyanide compound-aromatic vinyl compound copolymer (B) has a weight average molecular weight of 100,000 to 500,000, preferably 100,000 to 400,000. If the weight average molecular weight is less than 100,000, the fluidity is increased, but mechanical properties such as tensile strength and impact strength are not sufficient, and if the weight average molecular weight is higher than 500,000, the fluidity may be difficult to process the molded article.

In the present invention, the vinyl cyanide compound-aromatic vinyl compound copolymer (B) may be used in the range of 50 to 80 parts by weight. If the amount is less than 50 parts by weight, the fluidity is lowered, and when used in excess of 80 parts by weight, impact resistance may be reduced.

(C) thermally conductive additive

The thermally conductive additive of the present invention may be a low melting point metal and various types of ceramic series, preferably a fiber type ceramic series. Most preferably it is alumina fiber.

The thermally conductive additive may be a low melting point metal, alumina fiber or a mixture thereof. Preferably it is a mixture of the said low melting metal and alumina fiber.

The low melting point metal is a metal which is melted at a temperature significantly lower than a melting point of a general metal, and may be used as long as the product melts to some extent at the melting temperature of a resin which is a parent. If the melting point of the low melting point metal is too high, it cannot be used because it is a solid state such as lump when processing with the resin. If the melting point of the melting point metal is too low, there is a problem in kneading with the resin because the metal becomes a liquid such as water. . Therefore, a careful approach considering the processing temperature range is required. In the present invention, the low melting point metal may be a metal or an alloy having a melting point of 150 to 300 ° C., and a metal or an alloy having a melting point of 190 to 230 ° C. is preferable. The low melting point metal is preferably an alloy of tin and copper or a tin and aluminum alloy.

The low melting point metal is used in an amount of 0.1 to 10 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the base resin. When the low melting point metal is used in excess of 10 parts by weight, the appearance is not good, and the thermal conductivity improvement effect is insignificant while the price increases.

The alumina fiber of the present invention serves as a heat pathway so as to realize the basic high thermal conductivity of the metal well. This is because alumina acts as a bridge in the pores between the low melting point metals while maintaining physical properties, thereby expanding the heat transfer path.

The alumina fiber is used in an amount of 0.1 to 20 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the base resin. When using more than 20 parts by weight of alumina fiber, there is a disadvantage that the physical properties are lowered, the appearance is not good, and the price is increased.

The thermally conductive additive is used in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the base resin. When used in excess of 30 parts by weight, the thermal conductivity is improved, but the physical properties and appearance are inferior.

In the present invention, as the thermally conductive additive, the low melting point metal alone and the alumina fiber may be used alone, and the low melting point metal may be used based on 100 parts by weight of the base resin for synergistic effects according to the heat pathway role of the alumina fiber. Preference is given to using a mixture of 0.1 to 10 parts by weight and 0.1 to 20 parts by weight of alumina fiber. In particular, it is more preferable to use 5-10 weight part of low melting metals, and 10-20 weight part of alumina fibers.

The thermoplastic resin composition of the present invention may be prepared by further adding additives such as antioxidants, lubricants, impact modifiers, flame retardants, heat stabilizers, fillers, inorganic additives, pigments, dyes, and the like, depending on the respective uses. The additives may be applied alone or in mixture of two or more.

In the present invention, by molding the resin composition can be applied to a device that requires heat radiation. Heat exchangers such as heat exchangers for automobile radiators, heat exchangers for refrigerators, heat exchangers for air conditioners and the like; Heat sinks, substrates, housings, electrical connectors for electrical and electronic products; Industrial motors, spindle motors for hard disk drives, DVD motors, CD motors, and the like.

In addition, the resin composition of the present invention can be preferably applied particularly to refrigerator parts. For example, the resin composition is molded by a conventional method such as extrusion, injection, vacuum molding, die casting, and the like, and is applied to parts for refrigerators such as an IN-CASE for kimchi, a double door refrigerator dispenser, a lamp part, and the like.

The present invention will be further illustrated by the following examples, which are merely illustrative of the present invention and are not intended to limit or limit the scope of the present invention.

Example

The specifications of each component used in the following Examples and Comparative Examples are as follows.

(A) Graft copolymer resin: g-ABS resin CHT of Cheil Industries Co., Ltd. was used.

(B) Styrene-acrylonitrile copolymer resin: HN-5540 and HN-5381 which are SAN resin of Cheil Industries Co., Ltd. were used.

(C) Low melting point metal: LLS225 manufactured by Solder Co., Ltd., Japan.

(D) Alumina fiber: The ALS of Mitsui Chemicals, Japan was used.

Example 1

Using the same ingredients as described in Table 1 below, melt, kneading and extrusion to prepare pellets. At this time, the extrusion was used L / D = 32, 45 mm diameter twin screw extruder and the cylinder temperature was set to 260 ℃. The injection molding was performed on the pellets to measure impact strength, flowability, thermal softening point temperature and tensile strength. Then, 100 mm × 100mm × 3mm specimens were injection molded to measure thermal conductivity. The results are shown in Table 1 below.

Example 2

The same procedure as in Example 1 was repeated except that 10 parts by weight of alumina fiber (C-2) was used instead of the low melting point metal (C-1).

Example 3

It carried out similarly to Example 1 except having used the low melting metal (C-1) 10 weight part, and the alumina fiber (C-2) 10 weight part.

Example 4

The same procedure as in Example 1 was carried out except that 10 parts by weight of the low melting point metal (C-1) and 20 parts by weight of the alumina fiber (C-2) were used.

Comparative Example 1

The same procedure as in Example 1 was carried out except that nothing was added.

Comparative Example 2

The same procedure as in Example 1 was carried out except that 20 parts by weight of the low melting point metal (C-1) and 30 parts by weight of the alumina fiber (C-2) were used.

division Example Comparative Example One 2 3 4 One 2 A 40 40 40 40 40 40 B 60 60 60 60 60 60 C-1 10 - 10 10 - 20 C-2 - 10 10 20 - 30 Impact strength 27 19 14 11 30 6 Flow index 5.5 5.2 5.3 4.7 5.7 3.6 Thermosoftening point temperature 98 98 98 98 98 98 The tensile strength 400 350 360 320 380 300 Thermal Conductivity (W / mK) 0.4 0.4 0.7 0.8 0.2 1.3

The physical property evaluation was measured under the following conditions.

1. Impact strength was measured by ASTM D256 (1/4 ", 23 ℃, unit = Kgf · cm / cm).

2. Flow index was measured by ASTM D1238 (10Kg, 220 ℃, unit = g / 10min).

3. The thermal softening point temperature was measured by ASTM D1525 (5Kg, 50 ℃ / hr, unit = ℃).

4. Tensile strength was measured by ASTM D638 (5mm / min, unit = kgf / ㎠).

5. Thermal conductivity was measured using KYOTO ELECTRONICS 'Thermal Conductivity Meter.

As shown in the results of Table 1, it can be seen that the thermal conductivity of Examples 1 to 4 is very excellent thermal conductivity compared to Comparative Example 1. In addition, it can be seen that the difference in thermal conductivity is large according to the interaction of the low melting point metal and the alumina fiber, which are thermally conductive additives. This is because alumina acts as a bridge in the pores between the low melting point metals while maintaining physical properties, thereby expanding the heat transfer path.

Comparative Example 2 is used outside the scope of the present invention, the thermal conductivity improvement effect is great, but the physical properties are remarkable. That is, as the thermal conductivity additive is used in excess, the thermal conductivity is improved, but there is a cost burden and the physical properties are greatly reduced. Therefore, the use of the low melting point metal and the alumina fiber at the same time has a more positive effect.

The present invention is excellent in thermal conductivity, by eliminating carbon black or graphite, it is possible to implement a variety of colors, excellent balance of physical properties such as impact strength, fluidity, tensile strength, heat dissipation materials and kimchi refrigerator in-case (IN-CASE ) And a thermally conductive thermoplastic resin composition that can be applied to refrigerator components such as a double door refrigerator dispenser and a lamp part.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (10)

(A) 20 to 50 parts by weight of a graft copolymer resin containing 57 to 62% by weight of a rubbery polymer and having a graft ratio of 40 to 90%; And (B) 50 to 80 parts by weight of the vinyl cyanide compound-aromatic vinyl compound copolymer; With respect to 100 parts by weight of the base resin consisting of, (C) 0.1 to 30 parts by weight of the thermally conductive additive; And the thermally conductive additive (C) is selected from the group consisting of low melting point metals, alumina fibers, and mixtures thereof. The thermally conductive thermoplastic resin composition according to claim 1, wherein the graft copolymer (A) is a graft polymer of a rubbery polymer, an aromatic vinyl monomer and a vinyl cyanide monomer. The thermally conductive thermoplastic resin composition according to claim 2, wherein the rubbery polymer has an average rubber particle diameter of 0.25 to 0.4 mu m. delete The thermally conductive thermoplastic resin composition according to claim 1, wherein the vinyl cyanide compound-aromatic vinyl compound copolymer (B) has a weight average molecular weight of 100,000 to 400,000. The thermally conductive thermoplastic resin composition according to claim 1, wherein the low melting point metal is a metal or an alloy having a melting point of 150 to 300 ° C. The thermally conductive thermoplastic resin composition according to claim 6, wherein the low melting point metal is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the base resin. The thermally conductive thermoplastic resin composition according to claim 1, wherein the alumina fiber is used in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the base resin. The thermally conductive thermoplastic resin composition according to claim 1, wherein the mixture is a mixture of 0.1 to 10 parts by weight of the low melting point metal and 0.1 to 20 parts by weight of the alumina fiber with respect to 100 parts by weight of the base resin. The resin composition according to any one of claims 1 to 3 and 5 to 9, wherein the resin composition is an antioxidant, a lubricant, an impact modifier, a flame retardant, a heat stabilizer, a filler, an inorganic additive, a pigment, a dye, and their A thermally conductive thermoplastic resin composition further comprising an additive selected from the group consisting of mixtures.