KR100768633B1 - Thermoplastic elastomer resin composition for gasket of refrigerator - Google Patents

Abstract

The present invention relates to a thermoplastic elastomer resin composition for refrigerator gaskets, and more specifically, 5 to 25% by weight polypropylene, 5 to 20% by weight polyethylene, 20 to 40% by weight hydrogenated block copolymer, 10 to 40% by weight inorganic filler And a thermoplastic elastomer resin composition for a refrigerator gasket to which 1.0 to 10 parts by weight of a tackifier is added based on 100 parts by weight of the resin composition containing 15 to 35% by weight of the process oil. The non-halogen resin composition for refrigerator gaskets corresponding to the problem can be obtained.

Refrigerator, Gasket, Polyvinyl Chloride, Halogen, Thermoplastic, Elastomer

Description

Thermoplastic elastomer resin composition for refrigerator gaskets

The present invention relates to a thermoplastic elastomer resin composition for a refrigerator gasket, and more particularly, to have an environment similar to that of a conventional vinyl chloride resin, but does not contain chlorine, and thus does not contain harmful substances such as hydrogen chloride or dioxin when the gasket is incinerated. It relates to a resin composition.

In general, a soft vinyl chloride resin (hereinafter referred to as "PVC") is used to manufacture a refrigerator gasket. PVC can be produced using a relatively inexpensive equipment by the suspension polymerization method, and is a resin widely used because of excellent moldability and chlorine-containing flame retardancy and low material price. However, PVC generates hydrogen chloride gas upon combustion, which has a problem of damaging an incinerator because hydrogen chloride gas is not only harmful to the human body but also corrosive. Particularly when incinerated at low temperatures, the reaction pathway is not proven but is known to produce toxic dioxins. Chlorine is an ozone depleting substance, and as the use of vinyl chloride is increasingly regulated worldwide under the Environmental Protection Act, development of alternative materials is urgently required, and development competition is actively in progress.

An object of the present invention is to solve the problems of the prior art as described above, while exhibiting similar characteristics to the current soft vinyl chloride resin when used as a refrigerator gasket, environmental hormones such as dioxin and harmful at the time of disposal do not contain a halogen element It is to provide an environmentally friendly resin composition that does not generate a gas.

That is, the present invention is a resin composition comprising 5 to 25% by weight polypropylene, 5 to 20% by weight polyethylene, 20 to 40% by weight hydrogenated block copolymer, 10 to 40% by weight inorganic filler and 15 to 35% by weight process oil Provided is a thermoplastic elastomer resin composition for a refrigerator gasket to which 1.0 to 10 parts by weight of a tackifier is added per 100 parts by weight.

Hereinafter, the present invention will be described in more detail.

The polypropylene used in the present invention has an additional effect of imparting heat resistance and processing stability, and the kind thereof is not particularly limited as long as the object of the present invention is not impaired, and the melt index is 0.5 to 20 g / 10 minutes (ASTM D1238, 230). As polypropylene, isotactic polypropylene homopolymer, ethylene / propylene copolymer, or random polypropylene can be used. Among them, the isotactic polypropylene homopolymer is good in terms of heat resistance. If the melt index of the polypropylene is less than 0.5 g / 10 minutes, the flowability of the composition as a whole becomes poor and the moldability of the parts is not good, whereas if the melt index exceeds 20 g / 10 minutes, the other component of the composition is a hydrogenated block. Physical properties become unstable due to poor dispersion with the copolymer, which is not preferable.

The content of the polypropylene is 5 to 25% by weight in the resin composition before the pressure-sensitive adhesive is added. When the polypropylene content is less than 5% by weight, the heat resistance and fluidity of the final resin composition are lowered, while when the polypropylene content is higher than 25% by weight, the flexibility and the extrusion characteristics are lowered.

Polyethylene used in the present invention has the effect of improving the product melt properties and extrusion processability, low density polyethylene (LDPE) can be used, in particular the melt index is 0.1 ~ 5.0g / 10 minutes (190 ℃, 2.16kg) Preference is given to using low density polyethylene.

The content of polyethylene is 5 to 20% by weight in the resin composition before the pressure-sensitive adhesive is added. When the polyethylene content is less than 5% by weight, the melt properties and the extrusion properties of the final resin composition are lowered, whereas when the polyethylene content is more than 20% by weight, the heat resistance of the molded product is deteriorated.

The hydrogenated block copolymer used in the present invention includes at least one block A composed of homopolymer of styrene or a derivative thereof and one block B composed of homopolymer or copolymer of conjugated diene compound. At this time, the content of the block A is in the range of 5 to 60% by weight of the total block copolymer, and if it exceeds this range, the rigidity of the molded article becomes too high and flexibility cannot be maintained. Examples of the styrene derivatives constituting the block A include methyl styrene, 1,3-dimethyl styrene, vinyl naphthalene, propyl styrene, vinyl anthracene, and the like. Meanwhile, examples of the conjugated diene compound constituting the block B include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3 hexadiene, and the like. 70% or more are hydrogenated. If the hydrogenation rate is less than 70%, the weather resistance is sharply dropped, which is not preferable. The structure of the hydrogenated block copolymer having such a composition may be linear or branched.

The content of the hydrogenated block copolymer is 20 to 40% by weight in the resin composition before the pressure-sensitive adhesive is added. When the content of the hydrogenated block copolymer is less than 20% by weight, the flexibility of the molded article cannot be maintained, whereas when it exceeds 40% by weight, the fluidity is significantly reduced.

The inorganic filler used in the present invention serves as a reinforcement for the gasket holder, and it is possible to use any inorganic filler commonly used for this purpose, for example talc, calcium carbonate, clay, silica, alumina, carbon black , Magnesium hydroxide, carbon fiber, zeolite, barium sulfate and the like can be used.

The content of the inorganic filler is 10 to 40% by weight in the resin composition before the pressure-sensitive adhesive is added. When the inorganic filler content is less than 10% by weight, the strength of the molded article is inferior, whereas when the inorganic filler content is more than 40% by weight, the melt property and the extrusion characteristics of the resin composition are deteriorated.

Process oil used in the present invention is to increase the softening and fluidity of the resin composition, paraffin-based oil is preferred in terms of compatibility.                     

The content of the process oil is 15 to 35% by weight in the resin composition before the pressure-sensitive adhesive is added. If the process oil content is less than 15% by weight, the softening and flowability of the composition is lowered, while if the process oil content is more than 35% by weight, it is difficult to properly knead the kneading operation.

The pressure-sensitive adhesive used in the present invention may be a conventional petroleum resin known to be used with an elastomer to impart adhesion or adhesion to the elastomer as the thermoplastic petroleum resin, for example, piperylene and 2-methyl Diene-olefin copolymers of 2-butene, hydrogenated decyclopentadiene (DCPD) resins, and the like can be used. In particular, it is preferable to use a hydrogenated DCPD resin in order to obtain thermal stability.

The pressure-sensitive adhesive is added in a ratio of 1.0 to 10 parts by weight based on 100 parts by weight of the resin composition including all the components except the pressure-sensitive adhesive. If the amount of the pressure-sensitive adhesive added is less than 1.0 part by weight, a desired level of adhesive strength cannot be obtained. If the amount of the pressure-sensitive adhesive is more than 10 parts by weight, the fluidity of the composition is drastically lowered and extrusion molding is impossible.

In addition, various additives such as heat stabilizers, weather stabilizers, antistatic agents, lubricants, slip agents, antibacterial agents, nucleating agents, flame retardants, pigments, dyes, and the like may be added to the resin composition of the present invention without departing from the characteristics of the present invention. .

In the method for producing the resin composition of the present invention, a mechanical shearing method by material kneading using an extruder, a Benbury type mixer, or a brabender type mixer is used, and the compound is blended at a melting point of 170 to 250 ° C. or higher than a commonly known polypropylene melting point. It is possible to use processing conditions.

The molding obtained by extruding the resin composition thus prepared is cut to the front end, a magnet is inserted into the thread of the surface in contact with the iron plate of the refrigerator, and a foam is inserted into the corner portion to support the shape. You can get it.

The present invention can be understood in more detail by the following examples, the following examples are only examples for illustrating the present invention and are not intended to limit the protection scope of the present invention.

Examples and Comparative Examples

The content and physical property evaluation results of each component in the resin composition according to Example 1-2 are shown in Table 1 below. Detailed description of each component and the physical property evaluation method used in the Examples are as follows, a conventional PVC resin for refrigerator gaskets was used as a comparative example.

[ingredient]

1) Polypropylene: Polypropylene homopolymer with melt index 10 g / 10 min (230 ° C., 2.16 kg)

2) Polyethylene: Low Density Polyethylene with Melt Index of 1.0g / 10min (190 ℃, 2.16kg)

3) Hydrogenated block copolymer: Hydrogenated block copolymer having a styrene-ethylene / butylene-styrene structure (styrene / rubber content 33/67)

4) Inorganic filler: calcium carbonate with specific gravity of 2.7 and average particle size of 2.8 micrometers                     

5) Process oil: paraffinic hydrocarbon oil (viscosity 485 cSt 100 ℉)

6) Adhesive: Hydrogenated DCPD (decyclopentadiene) resin

[Property evaluation method]

1) Density: Measured at room temperature according to ASTM D792.

2) Hardness: Shore A value was measured at room temperature according to ASTM D2240.

3) Tensile strength: measured at room temperature at a rate of 150mm / min in accordance with ASTM D638.

4) Elongation: measured at room temperature at a rate of 150 mm / min according to ASTM D638.

5) Aging test: After leaving the sample in a thermostatic bath at 120 ° C. for 6 hours, hardness, tensile strength, and elongation were measured in the same manner as in 2) -4), and the respective rates of change were calculated.

6) Heat resistance: The length of the test piece was secured, and the dimensional change was measured after standing for 6 hours in a thermostatic bath at 100 ° C.

7) Cold resistance: The length of the test piece was secured, and the dimensional change was measured after standing for 6 hours in a 100 mm mark temperature -20 ° C in a thermostat.

8) Water resistance: The weight change was measured after leaving the sample in water at 100 ° C. for 6 hours.

9) Discoloration test: After half of the test piece was covered with a tape, the color change was measured after being left for 50 hours in ultraviolet light.

10) Restoration force: The sample was made into 200mm, and both sides were fixed by rotating 180 ° at 100mm point with φ30 round bar, and then restoring degree was measured after 30 minutes.

11) Welding force: After the heat treatment of the gasket corner, one side of the sample was fixed and the other side was fixed to the spring balance, and the pulling time was gradually measured while pulling the welded portion.

12) Extrusion: The extrusion characteristics and the appearance of the product to the extruder were visually and tactilely evaluated.

-○: There is no flaw by foreign material on the surface and it can be molded equally with PVC.

-X: There exists a fault by the foreign material on the surface, and it cannot shape | mold like PVC.

                                                           (Unit: parts by weight) division Example Comparative Example (PVC Gasket) One 2 One Polypropylene 70 70 Polyethylene 100 100 Hydrogenated Block Copolymer 280 280 Inorganic filler 300 300 Process oil 250 250 adhesive 20 50 Measurement result density 1.12 1.12 1.23 Shore A 65 64 67 Tensile Strength (kg / cm ² ) 1.00 1.03 1.08 % Elongation 675 617 232 Aging test (%) The tensile strength 4.1 6.4 7.1 Elongation 0.0 0.0 2.2 Hardness 5.6 3.4 6.0 Heat resistance (%) 0.3 1.0 0.8 Cold resistance (%) 0.8 0.3 0.7 Water resistance (%) 0.1 0.1 0.5 Fading test (ΔE) 1.2 1.3 1.8 dynamic stability(%) 98.0 98.6 98.3 Welding force (kg) 5.3 5.8 6.0 Extrusion Molding ○ ○ ○

As can be seen in Table 1, the thermoplastic elastomer resin composition according to the embodiment has a good second processability such as the surface of the molded article and the heat-sealing strength, and the existing PVC resin in heat resistance, weather resistance, water resistance, cold resistance, and other mechanical properties At least equivalent properties were demonstrated.

As described above in detail, the present invention can obtain a non-halogen resin composition for a refrigerator gasket corresponding to an environmental problem of a conventional PVC resin.

Claims (8)

5 to 25 weight percent polypropylene, 5 to 20 weight percent polyethylene, 20 to 40 weight percent hydrogenated block copolymer, 10 to 40 weight percent inorganic filler and 15 to 35 weight percent process oil A thermoplastic elastomer resin composition for a refrigerator gasket to which 1.0 to 10 parts by weight of a tackifier is added. The resin composition according to claim 1, wherein the polypropylene is an isotactic polypropylene homopolymer or a random polypropylene having a melt index of 0.5 to 20 g / 10 minutes (230 DEG C, 2.16 kg). The resin composition according to claim 1, wherein the polyethylene is a low density polyethylene having a melt index of 0.1 to 5.0 g / 10 minutes (190 DEG C, 2.16 kg). The resin according to claim 1, wherein the hydrogenated block copolymer comprises at least one block A consisting of a homopolymer of styrene or a derivative thereof and one block B consisting of a homopolymer or a copolymer of a conjugated diene compound. Composition. The said styrene derivative is 1 type chosen from the group which consists of methyl styrene, 1, 3- dimethyl styrene, vinyl naphthalene, propyl styrene, and vinyl anthrosene, The said conjugated diene compound is 1, 3- butadiene And isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3 hexadiene, wherein the resin composition is one or two or more selected from the group consisting of. The resin composition according to claim 1, wherein the inorganic filler is talc, calcium carbonate, clay, silica, alumina, magnesium hydroxide, carbon fiber, zeolite, or barium sulfate. The resin composition according to claim 1, wherein the process oil is a paraffinic oil. The resin composition according to claim 1, wherein the pressure-sensitive adhesive is a diene-olefin copolymer of piperylene and 2-methyl-2-butene or a hydrogenated decyclopentadiene (DCPD) resin.