KR20190035997A - Conductive shape memory sponge composition - Google Patents

Abstract

The present invention relates to a conductive shape memory sponge composition foamed by heat and recovered from a compressed state to an original shape at a specific temperature. The foaming sponge recovering to an original shape at a specific temperature, according to the present invention, is light with cells formed inside, easy to process, and can complement the assembly of complicated and tiny products. Further, according to the present invention, it is possible to discharge charged static electricity generated due to friction with the outside by having conductivity.

Description

[0001] CONDUCTIVE SHAPE MEMORY SPONGE COMPOSITION [0002]

TECHNICAL FIELD The present invention relates to a conductive shape memory sponge composition, and more particularly, to a conductive shape memory sponge composition which is electrically spontaneously foamed by heat and is recovered from a compressed state to an initial shape at a specific temperature.

Generally, a foam member is compressed and mounted on a required portion, and the thickness is restored by the elasticity of the material itself to fill the gap of the joint. However, since the conventional foam member is restored instantly when the pressure is released, It is necessary to mount the foam member while maintaining the state against the pressure of the gas. Further, when the foaming material is made thinner, the workability of the mounting improves, but there is a limitation that the performance such as sealing, soundproofing, and insulation is not sufficient because a gap is generated.

As described above, fluid sealing, soundproofing, heat insulating performance and mounting property are contradictory, and a sealing material satisfying each characteristic is required.

On the other hand, a thermally expandable material that thermally expandable resin composition containing a thermoplastic resin is disposed in a sealed portion and the sealing portion is foamed by heating to seal the gap is also used, but the manufacturing process is complicated, The rubber has a limitation in expanding all in the three-dimensional direction (thickness x width x length) at the time of foaming, and expanding only at a high temperature of 150 DEG C or higher.

Korean Patent Publication No. 10-0803869 Korean Patent Publication No. 10-2013-0068687

The present invention relates to a sponge material which is foamed by heat and which contains a crosslinked rubber, a crystalline thermoplastic resin, carbon black and a foaming agent and is expanded from a compressed state by heating at a relatively low temperature of 100 DEG C or less, To provide a shape memory sponge composition which is capable of restoring a shape in the form of a sponge and is easy to process by complementing the lightness and complexity of a complicated and minute product.

The present invention also provides a shape memory sponge composition which is different from the sponge rubber foamed in the conventional three-dimensional direction (thickness x width x length) and which is expanded only in the thickness direction to further improve the restoring force to the initial sponge shape.

The present invention also provides a conductive shape memory sponge composition which can discharge charge static electricity generated in friction with the outside by including conductive carbon black.

In order to achieve the above object, the conductive shape memory sponge composition according to the present invention is characterized in that it comprises an EPDM polymer, a crystalline thermoplastic resin, carbon black and a foaming agent, As the composition, the carbon black is characterized in that it comprises a furnace-based carbon black and a conductive carbon black.

The conductive shape memory sponge composition according to the present invention is a foam sponge that is restored to an initial shape at a specific temperature, and is formed as a cell in the interior thereof, which is light, easy to process, and can complement the assembling property of a complicated and fine product .

Further, according to the present invention, it is possible to discharge charged static electricity generated in friction with the outside by having conductivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a conductive shape memory sponge composition according to an embodiment of the present invention, according to the steps of foaming, compressing, and restoring. FIG.

Hereinafter, the conductive shape memory sponge composition according to the present invention will be specifically described.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of a conductive shape memory sponge composition according to an embodiment of the present invention, according to the steps of foaming, compressing, and restoring. As shown in FIG. 1, the conductive shape memory sponge composition according to the present invention is a composition capable of expanding by heating from a compressed state to be restored in shape, more specifically, a sponge foamed at a specific temperature of 100 to 180 ° C. The composition is compressed to a thickness of 200% or more by the external force, cooled and kept in a compressed shape, and the compressed material is expanded to 200% or more based on the thickness of the compressed state at a temperature of 60 to 120 캜, .

At this time, the conductive shape memory sponge composition according to the present invention is characterized in that the sponge composition expanded by heating is light with a specific gravity of 0.2 to 0.5 (test standard: KSM 3016 underwater substitution method) and has an electric resistance of 10 ⁷ ? Respectively.

The conductive shape memory sponge composition according to the present invention may contain an EPDM polymer, a crystalline thermoplastic resin, a carbon black and a foaming agent, wherein the carbon black may include furnace-based carbon black and conductive carbon black .

More specifically, the EPDM polymer is contained in an amount of 20 to 60% by weight, the crystalline thermoplastic resin is 10 to 50% by weight, the carbon black is 3 to 15% by weight based on the total weight of the composition of the present invention, 20% by weight.

The polymer used in the composition of the present invention is preferably an ethylene-propylene-diene copolymer (EPDM) rubber in terms of weather resistance and heat resistance, and is preferably used in an amount of 20 to 60% . When the content of the EPDM polymer which is an insulator is more than 60% by weight, it becomes an insulative material having little electrical conductivity, and the content of the polymer in the composition is increased and the workability is poor. When the content of the EPDM polymer is less than 20% There is a disadvantage that the content of carbon black to be added is increased and the foaming performance is deteriorated.

The EPDM polymer, which is an insulator used in the composition of the present invention, is a nonpolar rubber having excellent weatherability and heat resistance and excellent foamability. The content of EPDM polymer and the content of carbon black for conductive performance are mixed do.

The crystalline thermoplastic resin used in the composition of the present invention may be a polyolefin elastomer (POE), an ethylene vinyl acetate (EVA), or the like, depending on an expansion temperature condition, a processing condition, and the like required for the sponge composition according to the present invention. Etc. may be used.

More specifically, a resin having a melting point as an expansion temperature required for the sponge composition according to the present invention may be selected and used. The melting point of the crystalline thermoplastic resin may be 60 to 100 ° C.

In addition, the crystalline thermoplastic resin may be contained in an amount of 10 to 50% by weight based on the total weight of the composition for the intended effect. If the content of the crystalline thermoplastic resin is less than 10% by weight, it is difficult to maintain the compressed shape during cooling. If the content exceeds 50% by weight, the compressed material is hardly recovered to the initial shape.

The carbon black used in the composition of the present invention may include a furnace-based carbon black and a conductive carbon black. By mixing the furnace-based carbon black and the conductive carbon black in this way, it is possible to efficiently impart electrical conductivity to the composition while compensating for the problem of the reduction in the foaming efficiency due to the increase in viscosity that may occur when only conductive carbon black is used.

The furnace-based carbon black and the conductive carbon black may be contained in an amount of 1 to 10% by weight based on the total weight of the composition, respectively, for the desired effect, and the total content of the furnace- And is preferably 3 to 15% by weight based on the total weight of the composition in terms of foaming performance.

In addition, the conductive carbon black has a small particle size and a complicated molecular structure, and thus has excellent electrical conductivity as compared with a general furnace-based carbon black. However, the conductive carbon black has a small particle size, In the case of rubber, it is difficult to obtain a desired sponge rubber because of low foaming performance.

Therefore, in order to obtain a conductive sponge composition having excellent electric conductivity and excellent foaming performance, the furnace-based carbon black: conductive carbon black can be mixed in a ratio of more than 1: 1 and less than 1: 3 on the basis of weight, Can be mixed at a ratio of 1: 2.

As described above, the sponge composition according to the present invention contains the conductive carbon black, so that it is possible to provide the effect of discharging the charging static electricity generated in the friction with the outside.

As the foaming agent used in the composition of the present invention, azodicarbonamide (ADA) based foaming agent may be used. More preferably, azodicarbonamide modified at a decomposition temperature of 140 to 150 캜 can be used.

The foaming agent may be contained in an amount of 1 to 20% by weight based on the total weight of the composition for the purpose of effect. If the content of the foaming agent is less than 1% by weight, foaming can not be carried out and a foam cell in the form of a sponge can not be obtained. If it is more than 20% by weight, foaming reaction hinders rubber cross-linking and the degree of crosslinking is lowered and it is difficult to expect an elastic sponge rubber .

Hereinafter, the present invention will be described in more detail with reference to Examples and Test Examples. These examples and test examples are for further illustrating the present invention, and the scope of the present invention is not limited by these examples and test examples.

[Preparation Example 1] Preparation of shape memory sponge composition

The shape memory sponge materials of Example 1 and Comparative Examples 1 to 4 were prepared with the composition shown in Table 1 (unit: wt%). Specifically, the crystalline thermoplastic resin is sold under the trade name of Solumer 891 (SK General Chemicals), the furnace type carbon black is sold under the trade name N550S (OCI), the conductive carbon black is sold under the trade name Ketjen black J300 (Akzo Novel) The remaining EPDM, stearic acid, zinc oxide, calcium carbonate, sulfur, thiazole and dithio carbamate were sold on the market. The EPDM, stearic acid, zinc oxide, calcium carbonate, sulfur, thiazole and dithio carbamate were commercially available. Were purchased and used.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 EPDM 41 41 38 38 39 Crystalline thermoplastic resin 17 17 16 16 17 Stearic acid 0.5 0.5 0.5 0.5 0.5 Zinc oxide 6 6 6 6 6 Calcium carbonate 12 12 11 11 11 Furnace carbon black 6 0 6 3 3 Conductive carbon black 0 6 6 9 6 Paraffinic oil 8 8 7 7 8 blowing agent 7.5 7.5 7.5 7.5 7.5 brimstone One One One One One Thiazole 0.5 0.5 0.5 0.5 0.5 Dithio carbamate 0.5 0.5 0.5 0.5 0.5 TOTAL 100 100 100 100 100

 [Test Example 1] Evaluation of electric insulation and foaming performance of the shape memory sponge composition

The electrical insulating properties and presentation performance of the shape memory sponge compositions of Example 1 and Comparative Examples 1 to 4 prepared in Preparation Example 1 were evaluated.

Specifically, the compositions of Example 1 and Comparative Examples 1 to 4 were heated in an oven at 180 ° C for 20 minutes to foam, compressed at 4.0 to 6.0 kgf / cm ² pneumatic pressure, left at 80 ° C for 5 minutes or more Lt; / RTI >

Electrical insulation was measured based on JIS C 1302. The evaluation results are shown in Table 2 below.

Test Items Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Electrical Insulation (500V, Ω) 1.6 x 10 ^ 14 3.3 x 10 ^ 12 4.0 x 10 ^ 5 1.0 x 10 ^ 5 1.0 x 10 ^ 7 Foaming weight (KSM 3016) 0.338 0.395 0.439 0.47 0.4 Compression Thickness (mm) One 1.2 1.7 2 1.1 Expansion Thickness (mm) 3.2 3.11 3.4 2.9 3.5 Expansion ratio 320 259 200 145 318

In the results of Table 2, Comparative Examples 1 and 2 including only conductive carbon black or furnace based carbon black exhibited low foam specific gravity and high expansion efficiency. However, conductive carbon black and furnace based carbon black It was confirmed that the electrical insulating properties were remarkably higher than those of Comparative Examples 3 and 4 and Example 1, which contain both of them.

Therefore, when only conductive carbon black or furnace based carbon black alone is used, it is confirmed that it is difficult to exhibit conductivity.

In the case of Comparative Examples 3 and 4 in which both of the conductive carbon black and the furnace based carbon black were contained but the furnace based carbon black and the conductive carbon black were contained at a weight ratio of 1: 1 and 1: 3, respectively, the furnace type carbon black: The expansion ratio was reduced as compared with Example 1 in which the conductive carbon black was contained at a weight ratio of 1: 2, so that it was confirmed that foam performance and resilience were remarkably poor.

Therefore, in the case of the shape-memory sponge composition of Example 1 according to the present invention, Comparative Examples 1 and 2 including conductive carbon black or furnace-based carbon black alone, and conductive carbon black and furnace-based carbon black according to the present invention It was confirmed that the furnace-based carbon black and the conductive carbon black were contained together at a specific ratio in addition to the comparative examples 3 and 4, which contained outside of a specific ratio, and had conductivity with maintaining a light specific gravity and excellent foaming efficiency.

Claims (10)

1. A shape memory sponge composition comprising an ethylene-propylene-diene copolymer (EPDM) polymer, a crystalline thermoplastic resin, carbon black and a foaming agent,
Wherein the carbon black comprises furnace based carbon black and conductive carbon black. The method according to claim 1,
Wherein the EPDM polymer is contained in an amount of 20 to 60 wt%, the crystalline thermoplastic resin is contained in an amount of 10 to 50 wt%, the carbon black is contained in an amount of 3 to 15 wt%, and the foaming agent is contained in an amount of 1 to 20 wt% ≪ / RTI > the conductive shape memory sponge composition. The conductive shape memory sponge composition of claim 1, wherein the crystalline thermoplastic resin is a polyolefin elastomer (POE) or ethylene vinyl acetate (EVA). The method according to claim 1,
Wherein the furnace-based carbon black is contained in an amount of 1 to 10% by weight, and the conductive carbon black is contained in an amount of 1 to 10% by weight based on the total weight of the composition. The method according to claim 1,
Wherein the mixing ratio of the furnace-based carbon black and the conductive carbon black (furnace-based carbon black: conductive carbon black) is greater than 1: 1 and less than 1: 3 based on weight. The conductive shape memory sponge composition according to claim 1, wherein the foaming agent is azodicarbonamide. The conductive shape memory sponge composition according to claim 1, wherein the crystalline thermoplastic resin has a melting point of 60 to 100 캜. The conductive shape memory sponge composition of claim 1, wherein the expanded sponge composition by heating has a specific gravity of 0.2 to 0.8. The conductive shape memory sponge composition according to claim 1, wherein the conductive foam is expanded by 200% or more based on the thickness of the compressed state by heating. The conductive shape memory sponge composition of claim 1, wherein the composition has an electrical resistance of 1.0 x 10 < ⁷ >

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