COMPOSITION FOR GEL CUSHION, AND GEL CUSHION MANUFACTURED THEREFROM

Abstract

The present invention relates to a composition for a gel cushion and to a gel cushion manufactured therefrom, the composition for a gel cushion comprising 5-8 parts by weight of an additive based on 100 parts by weight of a mixture of an oil and a copolymer which is obtained by polymerization of a polystyrene-based polymer and polypropylene.

Claims

1. A composition for a gel cushion comprising 5 to 8 parts by weight of an additive with respect to 100 parts by weight of a mixture composed of an oil and a copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene.

2. The composition according to claim 1, wherein the polystyrene-based polymer has a triblock structure, and is a styrene-(ethylene/butylene)-styrene (SEBS) block copolymer or polystyrene-block-poly(ethylene-ethylene/propylene)-block-polystyrene (SEEPS).

3. The composition according to claim 1, wherein the mixture includes 30 to 40 wt % of the copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene and 60 to 70 wt % of the oil.

4. The composition according to claim 1, wherein the additive is dry silica or wet silica.

5. The composition according to claim 4, wherein the dry silica is fumed silica.

6. The composition according to claim 1, wherein the composition for a gel cushion has a hardness (Shore A) of 10 or less.

7. The composition according to claim 1, further comprising 0.3 to 0.7 parts by weight of a heat stabilizer with respect to 100 parts by weight of the mixture composed of the copolymer and the oil.

8. A gel cushion manufactured using the composition for a gel cushion according to any one of claims 1 to 7.

Description

DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is an image substituting for a plan view of a gel cushion manufactured using a composition for a gel cushion according to an embodiment of the present invention.

[0018] FIG. 2 is an image substituting for a partially perspective view of a gel cushion manufactured using a composition for a gel cushion according to an embodiment of the present invention.

[0019] FIG. 3 is an image after an oil blooming test for a gel cushion manufactured using a composition for a gel cushion according to an embodiment of the present invention.

[0020] FIG. 4 is an image illustrating the inside of a gel cushion manufactured using a composition for a gel cushion according to an embodiment of the present invention.

[0021] FIG. 5 is an image substituting for a plan view of a conventional gel cushion.

[0022] FIG. 6 is an image substituting for a partially perspective view of a conventional gel cushion.

[0023] FIG. 7 is an image after an oil blooming test for a conventional gel cushion.

[0024] FIG. 8 is an image illustrating the inside of a conventional gel cushion.

[0025] FIG. 9 is an image illustrating that gas is generated from a conventional gel cushion upon injection.

[0026] FIG. 10 is an image illustrating that a cushion is crushed due to degradation of properties of a conventional gel cushion.

MODES OF THE INVENTION

[0027] Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It should be understood by those skilled in the art that these embodiments are only exemplary for describing the present invention in more detail, and the present invention is not limited to the embodiments.

[0028] A composition for a gel cushion according to an embodiment of the present invention includes 5 to 8 parts by weight of an additive with respect to 100 parts by weight of a mixture composed of an oil and a copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene.

[0029] The polystyrene-based polymer has a triblock structure, and may be a styrene-(ethylene/butylene)-styrene (SEBS) block copolymer or polystyrene-block-poly(ethylene-ethylene/propylene)-block-polystyrene (SEEPS). In the specification, PP-SEBS, which is a copolymer prepared by copolymerizing SEBS as the polystyrene-based polymer and polypropylene, is described as an example, but the present invention is not limited thereto.

[0030] The mixture composed of an oil and a copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene preferably includes 30 to 40 wt % of the copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene and 60 to 70 wt % of the oil.

[0031] When a content of the oil is less than 60 wt %, hardness (Shore A) is increased and thus an effect of dispersing body pressure is decreased and a contraction rate is so high that ejecting is very difficult upon injection. On the other hand, when a content thereof is greater than 70 wt %, an oil and a copolymer are not easily mixed so that injection is not possible, and, even when injection is progressed, oil blooming is caused when it is used. For this reason, it is preferable that a content of the oil be within the above range.

[0032] In addition, 5 to 8 parts by weight of an additive is preferably included with respect to 100 parts by weight of the mixture composed of the copolymer and the oil. When a content of the additive is less than 5 parts by weight, an oil and a copolymer are not mixed and thus properties may be degraded. On the other hand, when a content thereof is greater than 8 parts by weight, hardness is increased. For this reason, it is preferable that a content of the additive be within the above range.

[0033] The additive is used to eliminate oil blooming and improve thermal resistance of a gel cushion, and dry silica or wet silica may be used. As dry silica, fumed silica is most preferably used.

[0034] In addition, the composition for a gel cushion according to an embodiment of the present invention may further include a heat stabilizer, as necessary, in order to prevent degradation caused by heating upon molding. In this case, 0.3 to 0.7 parts by weight of a heat stabilizer is preferably included with respect to 100 parts by weight of the mixture composed of the copolymer and the oil. As such a heat stabilizer, a heat stabilizer generally used in the art may be used without specific limitation, and may be organic phosphites such as triphenyl phosphite, tris-(2,6-dimethylphenyl)phosphite, tris-(mixed mono- and di-nonylphenyl)phosphite; phosphonates such as dimethyl benzene phosphonate; phosphates such as trimethyl phosphate; or a combination including at least one of the above-described heat stabilizers.

[0035] In addition, the composition for a gel cushion according to an embodiment of the present invention preferably has a hardness (Shore A) of 10 or less to meet performance of the gel cushion.

[0036] An optimum composition ratio according to hardness of the composition for a gel cushion according to an embodiment of the present invention is shown in the Table 1.

TABLE-US-00001 TABLE 1 Hardness (Shore A) 0 5 10 PP-SEBS copolymer 30 to 31 wt % 35 wt % 40 wt % White oil 69 to 70 wt % 65 wt % 60 wt % Fumed silica 7.5 to 8 pph 6.5 pph 5 pph Heat stabilizer 0.7 pph 0.5 pph 0.3 pph (antioxidant) * pph: Parts Per Hundred

[0037] A method of preparing the composition for a gel cushion consists of mixing an additive and a copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene (step 1), stirring the mixture prepared in step 1 and dropping an oil thereinto (step 2), and stirring the mixture prepared in step 2 using a mixer at an ultrahigh speed for 10 to 20 minutes to prepare a composition for a gel cushion (step 3). The composition for a gel cushion thus prepared is injected to manufacture a gel cushion.

[0038] More specifically, in step 1, an additive and a copolymer prepared by copolymerizing a polystyrene-based polymer and polypropylene are mixed, and an additive is mixed to eliminate oil blooming of a gel cushion. In step 2, the mixture prepared in step 1 is stirred and an oil is dropped thereinto for slightly adding an oil to mix an oil well. In step 3, the mixture into which an oil is dropped is stirred using a mixer at an ultrahigh speed for 10 to 20 minutes to prepare a composition for a gel cushion which is a gel-like raw material.

[0039] In step 3, the stirring is preferably performed in a bath at 40 to 50° C. at a speed of 5,000 to 6,000 rpm.

[0040] The composition for a gel cushion thus prepared is injected to manufacture a final product, a gel cushion. In this case, it is preferable that an injecting pressure be 15 kg/cm.sup.2 and a nozzle temperature be 250° C.

[0041] Hereinafter, a configuration of the present invention and effects according thereto will be described in more detail with reference to an example and comparative example. However, the example is for specifically describing the present invention in more detail, and the scope of the present invention is not limited to the example.

EXAMPLE

[0042] 14.3 parts by weight of fumed silica with respect to 100 parts by weight of PP-SEBS were mixed, 186 parts by weight of an oil (white oil) was added dropwise with stirring, and then the resulting mixture was stirred in a bath at 45° C. using a mixer at an ultrahigh speed of 5,200 rpm for 14 minutes to prepare a gel-like raw material. In this case, the hardness of a composition for a gel cushion was 5 Shore A (an optimum composition ratio according to hardness of 5 in Table 1). Afterward, a composition for a gel cushion which is the gel-like raw material was injected at an injecting pressure of 15 kg/cm.sup.2 and a nozzle temperature of 250° C. to manufacture a gel cushion.

Comparative Example

[0043] 186 parts by weight of an oil (white oil) with respect to 100 parts by weight of PP-SEBS were mixed with stirring to prepare a composition for a gel cushion, which was then prepared in a pellet form through extruding and pelletizing processes. Afterward, a raw material in a pellet form was injected at an injecting pressure of 15 kg/cm.sup.2 and a nozzle temperature of 250° C. to manufacture a gel cushion.

[0044] Gel cushions according to Example and Comparative Example were used to identify properties thereof as in the following Experimental Example. The results are shown in FIGS. 1 to 10.

Experimental Example

[0045] An oil blooming test according to an addition amount of fumed silica was performed. A cushion was covered with a cover, a weight of 10 kg was put thereon at 70° C., and then the cushion was left for 30 minutes.

[0046] Based on FIGS. 1, 2 and 4 illustrating an image substituting for a plan view of the gel cushion manufactured using the composition for a gel cushion according to an example of the present invention, an image substituting for a partially perspective view thereof and an image of the inside thereof, respectively, it was confirmed that the gel cushion according to Example exhibited no internal burrs and external burrs and had thermal resistance. In addition, based on FIG. 3 illustrating an image after an oil blooming test for the gel cushion manufactured using the composition for a gel cushion according to an example of the present invention, it was confirmed that the gel cushion did not exhibit oil blooming at all.

[0047] Meanwhile, based on FIGS. 5, 6 and 8 illustrating an image substituting for a plan view of a conventional gel cushion, an image substituting for a partially perspective view thereof and an image of the inside thereof, respectively, it was confirmed that the gel cushion according to Comparative Example exhibited both internal burrs and external burrs and did not have thermal resistance. In addition, based on FIG. 7 illustrating an image after an oil blooming test for the conventional gel cushion, it was confirmed that the gel cushion according to Comparative Example exhibited oil blooming. Additionally, based on FIG. 9 (the white part in the image represents an internal bubble caused by gas), it can be seen that gas was generated from the conventional gel cushion according to Comparative Example upon injection, and, based on FIG. 10, it was confirmed that a cushion was crushed due to degradation of properties.

[0048] Therefore, the composition for a gel cushion and the gel cushion manufactured therefrom according to the present invention has technological effects such as it is possible to prevent a pellet from sticking when a raw material is stored, to cause no oil blooming, to generate no internal burrs and external burrs, and to exhibit excellent thermal resistance.

[0049] In the specification, only a few examples of various examples conducted by the present inventors have been described, but the technological scope of the present invention is not limited thereto. It is clear to those skilled in the art that various modifications can be made.