KR100448144B1 - Composition of thermoplastic elastomer for powder-molding - Google Patents

Abstract

The present invention relates to an olefinic thermoplastic elastomer composition, and in particular, to a composition comprising a polypropylene, propylene-ethylene copolymer, hydrogenated butadiene rubber, ethylene-octene copolymer in a specific content, the composition of the present invention is melted It has excellent fluidity and powder molding, so it is easy to apply to interior materials and coating materials of automobiles, and has excellent tensile strength, fold recovery and physical properties.

Description

Composition of thermoplastic elastomer for powder molding {Composition of thermoplastic elastomer for powder-molding}

The present invention relates to an olefinic thermoplastic elastomer composition, and in particular, to a composition comprising a polypropylene, propylene-ethylene copolymer, hydrogenated butadiene rubber, ethylene-octene copolymer in a specific content, the composition of the present invention is melted It has excellent fluidity and powder molding, so it is easy to apply to interior materials and coating materials of automobiles, and has excellent tensile strength, fold recovery and physical properties.

In the case of the skin or covering material used for automotive interior materials such as instrument panels, door trims, console boxes, armrests, headrests, etc., products are required to be lighter in weight, improved in quality, and more complicated and refined in shape. In addition, in terms of environmental preservation, the need for environmentally friendly materials that can be easily recycled at the time of disposal of waste cars or that no acidic substances are generated during incineration has been greatly increased.

Conventionally known skin or coating materials for automobile interiors include vacuum of sheets made of vinyl chloride resin (hereinafter referred to as "PVC") and atrylonitrile-butadiene- styrene-copolymer (hereinafter referred to as "ABS"). Molded articles, powder molded articles made of PVC resin and plasticizer, and the like, sol molded articles made of emulsion PVC method, sol molded articles made of plasticizer and the like, and vacuum molded articles of sheets made of TPO.

In the case of the product using the PVC resin is not easy to regenerate, the acid is generated during incineration is insufficient in an environmentally friendly aspect, there is a disadvantage that it is difficult to achieve the product light weight due to the high specific gravity of the PVC resin itself. In the case of the product manufactured by vacuum molding using PVC sheet and TPO sheet, the surface hardness is high, so the feel is not good, the embossing pattern is weakened, it is difficult to manufacture in complicated shape, and it is used for a long time due to residual stress during molding. There is a disadvantage that the product is deformed after. In addition, sol molded products have a soft feeling, but there is a problem in that it is difficult to preserve raw materials for a long time due to variation in product thickness and flow marks and change in sol viscosity.

Therefore, the development of TPO composition capable of powder molding has recently been made. For example, Korean Patent Publication Nos. 95-12102 and 95-12106 include part of ethylene-alpha-olefin copolymer rubber and polyolefin resin containing mineral oil. Crosslinked elastomer compositions have been proposed. However, such a composition is poor in melt flowability, resulting in molded product appearance pinholes, and has disadvantages such as a lack of back surface smoothness. In addition, since the hardness is high for increasing mechanical properties such as tensile strength, there is a problem in that the soft touch of the molded product is insufficient and the molded product is hard, so that it is difficult to restore the folded part generated during product demoulding and handling of the molded product, and thus the fold marks remain severe. .

In order to solve the problems of the prior art, the present inventors have developed an elastomer composition based on an olefin-based thermoplastic resin and improving moldability by increasing melt flowability so that pinholes are less generated on the surface of the molded product and excellent in meltability at the rear side. It was.

As a result, an olefinic thermoplastic elastomer composition containing polypropylene, propylene-ethylene copolymer, hydrogenated butadiene rubber, and ethylene-octene copolymer in a specific content was developed. The present invention was completed by finding that it is easy to be applied to interior materials and coating materials, and has excellent characteristics of tensile strength and folded site restorability and physical properties.

Accordingly, it is an object of the present invention to provide an olefinic thermoplastic elastomer composition which is excellent in melt fluidity and capable of powder molding.

Specifically, the present invention provides an olefin-based thermoplastic elastomer composition containing a polypropylene, propylene-ethylene copolymer, hydrogenated butadiene rubber, and ethylene-octene copolymer in a specific content.

In addition, another object of the present invention is to provide a powder molding material in a powder state prepared using the olefinic thermoplastic elastomer composition.

The present invention relates to 100 parts by weight of a polypropylene resin having a melt index (Melt Index, ASTM D1238) of 50 to 300 g / 10 min at 230 ° C. and 2.16 kg load, and a melt index of 3 to 50 g / at 230 ° C. and 2.16 kg load. 5 to 150 parts by weight of propylene-ethylene copolymer resin, 10 minutes, Shore D hardness (ASTM D2240) 40 or less, hydrogenated styrene having a melt index of at least 5 g / 10 minutes and a styrene content of 5 to 20% under a load of 230 ° C. and 2.16 kg. 50 to 200 parts by weight of butadiene rubber, 50 to 200 parts by weight of ethylene-octene copolymer elastomer having a pattern viscosity (ML1 + 4, ASTM D 927) measured at 121 ° C of 1 to 10 and a Shore A hardness (ASTM D 2240) of 80 or less It comprises the thermoplastic olefin elastomer composition for powder molding containing it.

The present invention is further characterized by a powder molding material in a powder state prepared using the olefinic thermoplastic elastomer composition.

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an olefinic thermoplastic elastomer composition and a powder molding material, and is excellent in melt flowability, making it easy to manufacture a molded article by a powder molding method, and the molded article has suitable physical properties as a skin or coating material.

The polypropylene resin, propylene-ethylene copolymer resin, hydrogenated styrene-butadiene rubber, and ethylene-octene copolymer elastomer used in the present invention have excellent compatibility with each other and are easily kneaded without using a separate compatibilizer.

The polypropylene resin serves to maintain proper physical properties such as tensile strength of molded articles and to improve moldability by reducing melt viscosity during powder molding. It is preferable that the polypropylene resin has a melt index of 50 to 300 g / 10 minutes under a load of 230 ° C. and a 2.16 kg load. However, when the melt index is low, the formability is poor, pinholes are generated, and the back side melt state is lowered. In this case, there is a problem in that physical properties are lowered due to a decrease in molecular weight, and most preferably, a melt index of 100 to 250 g / 10 minutes is used.

The propylene-ethylene copolymer resin has a lower rigidity than the polypropylene resin, but has good flexibility, thereby reducing the content of expensive rubber components, and good melt flowability, which is effective for improving moldability. It is preferable to mix 5 to 150 parts by weight with respect to 100 parts by weight of polypropylene resin, but when it is added in a large amount, the physical properties are lowered, and when it is added in a small amount, the effect of improving flexibility is insufficient, and more preferably 20 to 100 parts by weight is used. In addition, the melt index of the propylene-ethylene copolymer resin at 230 ° C. and 2.16 kg load is 3 to 50 g / 10 min, preferably Shore D hardness of 40 or less, and the higher melt index is lower in molecular weight of the resin, resulting in reduced physical properties. If the melt index is low, the moldability is poor, and more preferably, the melt index is 5 to 40 g / 10 minutes. If the Shore D hardness is high, the flexibility is lowered, thereby reducing the rubber component reduction effect and increasing the hardness of the molded article. Therefore, the thing of Shore D hardness 35 or less is used more preferably.

Hydrogenated styrene butadiene rubber is added to give flexibility and elasticity of the composition. It is preferable to mix 50 to 200 parts by weight with respect to 100 parts by weight of polypropylene resin, but when it is added a lot, the melt fluidity is lowered and the back gelling state is lowered. And when the moldability, such as embossed pattern transfer state is lowered and less added, the molded article becomes hard, cold resistance and cold recovery resistance is lowered, more preferably 100 to 150 parts by weight. In addition, the melt index of the hydrogenated styrene butadiene rubber at 230 ° C. and a load of 2.16 kg is preferably 5 g / 10 minutes or more. However, when the melt index is low, moldability is lowered, so more preferably 7 g / 10 minutes or more. The styrene content of the hydrogenated styrene butadiene rubber is preferably 5 to 20%, but the styrene content is 7 to 15 is more preferable because the flexibility and elasticity is reduced when the styrene content is low and the melt fluidity is lower when the styrene content is low. % to be.

Ethylene-octene copolymer elastomer is added to give elasticity and soft feel of molded products due to its excellent flexibility. It is preferable to mix 50 to 200 parts by weight with respect to 100 parts by weight of polypropylene resin, but when added a lot, the physical properties are deteriorated. When less is added, the molded article becomes harder and the restorability is lowered, and more preferably 70 to 150 parts by weight. In addition, the ethylene-octene copolymer elastomer has a pattern viscosity (ML _{1 + 4} ) measured at 121 ° C of 1 to 10 and a Shore A hardness of 80 or less. When the viscosity is low, the physical properties are lowered, and more preferably, the pattern viscosity is 2 to 7, and when the Shoa A hardness is high, the flexibility and elasticity of the molded article are reduced, and more preferably, Shoa A hardness is 75 or less.

In addition, it is possible to add an additive to the composition for various purposes, the type and content thereof may be made by those skilled in the art.

The manufacturing method of the olefinic thermoplastic elastomer composition in this invention is as follows.

Specifically, the polypropylene resin, the propylene-ethylene copolymer resin, the hydrogenated styrene-butadiene rubber, the ethylene-octene copolymer elastomer by dry blending using a tumbling mixer or a high speed rotary mixer, and then a twin screw extruder or half heated to 150 to 240 ° C. Pellets are heated and kneaded with a vari mixer.

Provided is a powder molding material in a powder state prepared using the obtained olefinic thermoplastic elastomer composition.

The composition processed in the pellet state is frozen to cryogenic temperature below -190 ℃ using liquefied nitrogen, and then pulverized with a disk mill to prepare an olefin-based thermoplastic elastomer powder passing through a 40 mesh body of Taylor standard.

As a result of measuring the physical properties of the composition prepared according to the present invention, the Shore A hardness (softness) is 75 to 85 levels and the tensile strength is 90 to 120 kg / cm ² level, instrument panel, door trim, console box, arm It is applied to the skin material or the cover material which is used for automobile interior materials such as the rest and the headrest, so that the product can be made light in weight, improved in quality and complicated and refined in shape. In addition, it is good in terms of tensile strength and flexibility, and the restoration of the folded part, and it is easy to regenerate and use the molded article, and since the acidic material is not generated during incineration disposal, there is an environmentally friendly effect.

Hereinafter, the present invention will be described in more detail with reference to Examples.

However, the following examples are merely to illustrate the content of the present invention is not limited to the scope of the present invention.

Examples 1-5 and Comparative Examples 1-8

The olefin-based thermoplastic elastomer composition was prepared by dry blending a polypropylene resin, a propylene-ethylene copolymer resin, a hydrogenated styrenebutadiene rubber, and an ethylene-octene copolymer elastomer using a high speed rotary mixer in the composition shown in Table 1 below.

Test example. Property measurement

In order to measure the physical properties of the compositions prepared in Examples and Comparative Examples was carried out as follows.

First, a powder in powder form prepared using the obtained olefinic thermoplastic elastomer composition was prepared. The composition processed in the pellet state was frozen to cryogenic temperature below -190 ° C using liquefied nitrogen, and then pulverized with a disk mill to prepare an olefinic thermoplastic elastomer powder passing through a 40 mesh body of Taylor standard.

Method for producing a molded specimen using the powder is as follows.

First, the powder is placed in a 20 × 20 cm powder supply box, and the 20 × 20 cm flat pole mold with an embossed pattern heated at 240 ° C. is fastened with the powder supply box, and then the mold and the powder supply box are clockwise together. And it rotated three times counterclockwise, and shaken off the excess powder stuck to the metal mold | die. Then, the mold was separated, heated in a heating furnace at 270 ° C. for 1 minute, and then cooled in water to form a molded specimen by demolding the molded sheet.

About the manufactured sheet, the pinhole generation state and the back side melt state were visually observed and scored, and the moldability was evaluated. Pinhole generation was evaluated by observing the pinhole generation distribution on the surface of the molded sheet and scoring the score from 5 to 1 point. Five points and a case where the pinholes were not severely generated were set at one point, and the intermediate degree was evaluated by dividing it into four to two points.

The back melting state was also evaluated by scoring from 5 to 1 point. If the back melting state of the molded sheet was smooth and smooth, 5 points were used, and if the unevenness was severe, 1 point was set and the middle was 4 to 2 points. It was evaluated separately.

In addition, Shore A hardness (ASTM D2240) and tensile strength (ASTM D638) were measured on the manufactured sheet to evaluate flexibility and physical properties.

Restoration test related to the fold occurrence is to fold the 2 × 10 cm molded sheet into 2 × 5 cm, press the folded part with a 5 kg weight for 1 minute, remove the weight, and measure the angle of the folded part with a protractor after 3 minutes to measure the degree of restoration. Evaluated.

The obtained physical properties are shown in Table 2 below.

According to the above Table 2, the composition of the Example is less pinhole generation than that of the comparative example, it can be seen that the back side melt state is also very good. Hardness and tensile strength have already satisfied the values required for the use of interior materials, as described above. In addition, the restoration angle is much superior to that of the comparative example, and it can be predicted that the problem of product folding marks remaining during the demolding process or the handling of the molded product can be improved.

Therefore, according to the present invention, an olefin-based thermoplastic elastomer composition including polypropylene, propylene-ethylene copolymer, hydrogenated butadiene rubber, and ethylene-octene copolymer having a good melt flowability and powder molding in a specific content was prepared. While exhibiting the high-quality texture and feel required for this automobile interior material, it was possible to improve the problem of product folds remaining during the demolding process or the handling of the molded product. In addition, it is easy to regenerate and use the molded article, and since the acidic material is not generated even when incinerated, there is an environmentally friendly effect.

Claims (3)

delete For 100 parts by weight of a polypropylene resin having a melt index (Melt Index, ASTM D1238) at 230 ° C. and a 2.16 kg load of 50 to 300 g / 10 min, 5 to 150 parts by weight of a propylene-ethylene copolymer resin having a melt index of 3 to 50 g / 10 minutes under a load of 230 ° C. and a 2.16 kg load and a Shore D hardness (ASTM D2240) of 40 or less; 50 to 200 parts by weight of hydrogenated styrenebutadiene rubber having a melt index of 5 g / 10 min or more and a styrene content of 5 to 20% under a load of 230 ° C. and a 2.16 kg, Powder molding characterized in that it comprises 50 to 200 parts by weight of an ethylene-octene copolymer elastomer having a pattern viscosity (ML1 + 4, ASTM D 927) measured at 121 ° C of 1 to 10 and a Shore A hardness (ASTM D 2240) of 80 or less. Thermoplastic olefin elastomer composition. Powder molding material prepared using the composition of claim 2.