KR100571035B1 - Ethylene-propylene copolymer resin composition with gamma-ray stability - Google Patents

Abstract

The present invention relates to a gamma-resistant ethylene-propylene copolymer resin composition, and more particularly, an ethylene-propylene copolymer having a melt index of 0.1 to 20 g / 10 min and an ethylene content of 0.5 to 50 wt% at 230 ° C., The present invention relates to an anti-gamma resistant ethylene-propylene copolymer resin composition comprising an amine light stabilizer and a non-phenolic antioxidant. The resin composition of the present invention exhibits excellent gamma-ray resistance such as physical property deterioration of the resin even after gamma-irradiation, transparency is maintained, and discoloration is suppressed. In particular, the material of various medical instruments to be sterilized by irradiation with radiation Suitable for use as

Gamma-Resistance, Ethylene-Propylene Copolymer, Biphenol Antioxidant

Description

Gamma-ray-resistant ethylene-propylene copolymer resin composition {ETHYLENE-PROPYLENE COPOLYMER RESIN COMPOSITION WITH GAMMA-RAY STABILITY}

The present invention relates to a gamma-resistant ethylene-propylene copolymer resin composition, and more particularly, an ethylene-propylene copolymer having a melt index of 0.1 to 20 g / 10 min and an ethylene content of 0.5 to 50 wt% at 230 ° C., The present invention relates to an anti-gamma resistant ethylene-propylene copolymer resin composition comprising an amine light stabilizer and a non-phenolic antioxidant.

In order to solve the problem of bacterial or virus infection through medical devices and devices, the demand for disposable medical devices using polymer materials is rapidly increasing in the field of medical devices. Interest is also increasing. Since disposable medical devices have a basic purpose of preventing infection, they must be sanitized in various sanitary or sterilized conditions before or after their manufacture so that they can be safely used in a special environment where infection is particularly careful. Therefore, it is required that the polymer material used in the production of these disposable medical instruments has no or no change in physical properties and general characteristics even under such various sterilization or sterilization conditions.

Radiation sterilization is a method of sterilizing microorganisms by irradiating a medical device with radiation, and is widely used because it is a fairly simple and reliable sterilization method. However, when a medical device made of a polymer material is treated by radiation sterilization, it is irradiated radiation and affects the inside of the molecular material, resulting in the decomposition and crosslinking of the polymer chains, resulting in physical and chemical properties of the polymer material. It can cause a change.

Polypropylene has excellent transparency, mechanical properties, and the like compared to other general-purpose resins, but has been limited in its application to medical instruments requiring sterilization because of its great property of decomposition due to oxidation by irradiation. In order to improve the radiation-induced degradability of such polypropylene, there have been attempted blending with other polymers, copolymerization, control of crystallinity and molecular weight distribution, addition of stabilizers such as antioxidants and radical scavengers, and the like. In particular, many attempts have been made to improve radiation-induced degradability by adding various stabilizers. Among them, in the early method of adding a small amount of phenolic antioxidant to homopolypropylene, there is a problem of discoloration after irradiation. It was. To solve this problem, a specific amine compound and a phosphite compound are added to polypropylene together with a phenolic antioxidant (US Pat. No. 4,666,959), or various amine compounds and phenol and phosphorus compounds are added to the resin composition. (US Pat. No. 5,041,483), but the physical property degradation of the product still occurred after irradiation. On the other hand, Korean Patent Publication No. 1997-0011464 discloses a polypropylene resin composition using phosphorus antioxidants, phenolic antioxidants and amine light stabilizers that can reduce the degree of discoloration without severe degradation of properties after irradiation. have. However, when attempting to improve the radiation stability of the resin composition only by using the additives as in the related arts, the amount of the additives may be excessively increased, which may lead to regulation. Development of a resin composition is calculated | required.

The present invention is to solve the problems of the prior art as described above, an object of the present invention, ethylene-propylene is maintained after the radiation is not deteriorated in physical properties, almost no discoloration due to deterioration, the existing transparency It is to provide a copolymer resin composition.

According to the present invention, the melt index at 230 ° C. is from 0.1 to 20 g / 10 min and the ethylene content of 95 to 97.7 wt% of the ethylene copolymer of 0.5 to 50 wt%, the amine light stabilizer from 0.01 to 1 wt% and the biphenol Provided is a gamma-resistant ethylene-propylene copolymer resin composition comprising 0.01 to 1% by weight of a non-phenolic antioxidant.

It is preferable that the melt index in 230 degreeC of the said ethylene-propylene copolymer contained in the resin composition of this invention is 0.1-20 g / 10min, and it is preferable that the ethylene content in a copolymer is 0.5-50 weight%. If the melt index at 230 ° C. is less than 0.1 g / 10 min, the workability is inferior and there is a limit to the use for general purpose applications. In addition, when the ethylene content of the copolymer is less than 0.5% by weight, after the gamma irradiation, physical properties are lowered and discolored, transparency is worsened, and when it exceeds 50% by weight, heat resistance and mechanical properties are deteriorated.

The ethylene-propylene copolymer contains 65 to 95% by weight of the crystalline ethylene-propylene random copolymer component and 5 to 35% by weight of the elastic ethylene-propylene copolymer component, and has an isotactic index value. It is preferable that it is this ethylene-propylene block copolymer which is 92 to 99.7%. If the content in the block copolymer of the crystalline ethylene-propylene random copolymer component is less than 65% by weight, the thermal and mechanical properties deteriorate, and if it exceeds 95% by weight, the transparency deteriorates. Moreover, when content in the said block copolymer of the said elastic ethylene propylene copolymer component is less than 5 weight%, impact resistance will worsen, and when it exceeds 35 weight%, dispersibility will become low and transparency will worsen.

The block copolymer is prepared by first introducing ethylene and propylene into a polymerization reactor at the same time to produce a crystalline ethylene-propylene random copolymer, and then a part of the crystalline ethylene-propylene random copolymer is subjected to a series of reactions. Prepared by conversion to the propylene copolymer component. Therefore, in the block copolymer thus prepared, the crystalline ethylene-propylene random copolymer component and the elastic ethylene-propylene copolymer component are present together.

The ethylene content of the crystalline ethylene-propylene random copolymer component is preferably 0.5 to 15% by weight. If the ethylene content is less than 0.5% by weight, the degree of crystallinity of the copolymer becomes higher than necessary to decrease the transparency of the composition. If the content of the ethylene content exceeds 15% by weight, the degree of crystallinity decreases rapidly. It is not suitable for the material of.

In addition, the ethylene content of the elastic ethylene-propylene copolymer component is preferably 20 to 70% by weight, and the absolute viscosity is preferably 0.5 to 1.5 dl / g. If the ethylene content is less than 20% by weight or more than 70% by weight, the elasticity of the polymer is reduced to lower the impact resistance. In addition, if the intrinsic viscosity is less than 0.5 dl / g, the dispersibility is good immediately after molding during processing of the block copolymer composition, but as the crystallization of the ethylene-propylene random copolymer component proceeds, the elastic ethylene- The phenomenon that the propylene copolymer component crawls out on the surface of the molded product occurs, resulting in a decrease in transparency and greatly deteriorating the appearance of the product. On the other hand, when the absolute viscosity exceeds 1.5 dl / g, the dispersibility of the elastomeric copolymer component during molding of the block copolymer composition is lowered and the transparency is reduced.

The said amine light stabilizer contained in the resin composition of this invention is included in order to give ultraviolet stability to a resin composition, It is preferable that it is a hindered amine type compound, It is 0.01-1 weight in a resin composition It is preferred to include%. If the content is less than 0.01% by weight, the UV stability of the resin composition is lowered, and if the content is more than 1% by weight, the mechanical properties of the molded article are deteriorated, and the total amount of the additive is increased.

The non-phenolic antioxidant contained in the resin composition of the present invention is included to prevent physical degradation and discoloration caused by irradiation, and is preferably a hydroxyamine-based compound or a lactone-based (substituted benzofuranone-based) compound. It is more preferable that it is a hydroxyamine type compound, and it is preferable that 0.01-1 weight% is contained in a resin composition. If the content is less than 0.01% by weight, there is a disadvantage in that the reduction of physical properties and discoloration prevention effect due to radiation is reduced, and when the content is more than 1% by weight, the mechanical properties of the molded product deteriorate and the total amount of the additive is increased.

In the resin composition of the present invention, aluminum hydroxy di-tert-butyl benzoate, which is an aluminum-based nucleating agent, and sodium 2,2'-methylene bis (4,6-, which is a sodium-based nucleating agent, are used as nucleating agents for improving transparency of the resin composition. One or two or more compounds selected from di-tert-butylphenyl) phosphate or sorbitol-based nucleating agent benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, or 3,4-dimethylbenzylidene sorbitol may be further included. Preferably, the nucleating agent in an amount corresponding to 0.01 to 1% by weight of the total resin composition is further included in the resin composition. If the amount contained is less than 0.01% by weight of the total resin composition, the transparency of the resin composition does not improve. If the amount is more than 1% by weight, the mechanical properties of the molded article deteriorate, and the total amount of the additive is increased.

In addition to the components described above, the resin composition of the present invention may further include components generally added to the resin composition within the scope of achieving the object of the present invention. For example, in order to neutralize the catalyst residue remaining in the polymer after being used in polymer synthesis, 0.05 to 1.0% by weight of calcium stearate may be further included in the resin composition of the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1

As shown in Table 1 below, 99.5% by weight of an ethylene-propylene copolymer resin (trade name: RJ500, manufactured by Samsung Atopina Co., Ltd.), having a melt index of 10 g / 10 minutes and an ethylene content of 2.6% by weight, as a base resin. Amine light stabilizer (trade name: TINUVIN 770, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.1% by weight, 0.1% by weight of oxidized bis (hydrogenated tallowalkyl) amine as a biphenol-based antioxidant, and a nucleating agent 0.2 wt% of 3,3,4-bis-o- (3,4) -dialkyl benzylidene sorbitol-based nucleating agent and 0.1 wt% calcium stearate as catalyst residue neutralizer were mixed using a Henschel mixer, and then 2 The resin composition was prepared by melt extrusion through a screw extruder to pelletize.

Test specimens were prepared from the resin composition pellets prepared as described above to measure tensile strength, tensile elongation, haze and yellowness index (YI). Next, after irradiating gamma rays (2.5 × 10 4 Gy, 2.5 Mrad) to the test pieces, the items were measured again. Table 1 shows the results of measuring physical properties before and after gamma irradiation.

Example 2

As the basic resin, 99.5% by weight of an ethylene-propylene block copolymer resin (trade name: CS500, manufactured by Samsung Atopina Co., Ltd.) having a melt index of 10 g / 10 minutes, an ethylene content of 8.3% by weight, and an isotactic index value of 98% A resin composition was prepared in the same manner as in Example 1 except that it was used. The base resin contains 79 wt% of the crystalline ethylene-propylene random copolymer component (2.4 wt% of ethylene) and 20 wt% of the elastic ethylene-propylene copolymer component (32 wt% of ethylene, 1.1 kPa / g absolute viscosity). Was an ethylene-propylene block copolymer resin.

Using the prepared resin composition, a test piece was prepared in the same manner as in Example 1, and the physical properties of the same items as in Example 1 were measured in the same manner as in Example 1 before and after gamma-irradiation using the same, and the measurement results were listed in the table. 1 is shown.

Comparative Example 1

99.5% by weight of a propylene homopolymer (trade name: HJ700, manufactured by Samsung Atopina Co., Ltd.) having a melt index of 10 g / 10 minutes as a basic resin, and a phenolic antioxidant (trade name: IRGANOX 1010, Ciba instead of a non-phenolic antioxidant) A resin composition was prepared in the same manner as in Example 1, except that 0.1 wt% of (Ciba) Specialty Chemicals Co., Ltd. was used.

Using the prepared resin composition, a test piece was prepared in the same manner as in Example 1, and the physical properties of the same items as in Example 1 were measured in the same manner as in Example 1 before and after gamma-irradiation using the same, and the measurement results were listed in the table. 1 is shown.

Comparative Example 2

A resin composition was prepared in the same manner as in Example 1, except that 99.5% by weight of propylene homopolymer (trade name: HJ700, manufactured by Samsung Atopina Co., Ltd.) was used as the basic resin.

Using the prepared resin composition, a test piece was prepared in the same manner as in Example 1, and the physical properties of the same items as in Example 1 were measured in the same manner as in Example 1 before and after gamma-irradiation using the same, and the measurement results were listed in the table. 1 is shown.

Comparative Example 3

A resin composition was prepared in the same manner as in Example 1, except that 0.1 wt% of a phenolic antioxidant (trade name: IRGANOX 1010, manufactured by Ciba Specialty Chemicals, Inc.) was used instead of the nonphenolic antioxidant.

Using the prepared resin composition, a test piece was prepared in the same manner as in Example 1, and the physical properties of the same items as in Example 1 were measured in the same manner as in Example 1 before and after gamma-irradiation using the same, and the measurement results were listed in the table. 1 is shown.

Comparative Example 4

A resin composition was prepared in the same manner as in Example 2, except that 0.1 wt% of a phenolic antioxidant (trade name: IRGANOX 1010, manufactured by Ciba Specialty Chemicals, Inc.) was used instead of the nonphenolic antioxidant.

Using the prepared resin composition, a test piece was prepared in the same manner as in Example 1, and the physical properties of the same items as in Example 1 were measured in the same manner as in Example 1 before and after gamma-irradiation using the same, and the measurement results were listed in the table. 1 is shown.

Property measurement method

① Melt Index

According to ASTM D1238 it was measured with a load of 2.16 kg at 230 ℃.

② Tensile strength and tensile elongation

A No. 4 specimen was prepared and measured according to ASTM D638.

③ Cloudiness

It measured according to ASTM D1003.

④ Yellow degree

It measured based on ASTMD1925.

TABLE 1

Example Comparative example One 2 One 2 3 4 Ethylene-propylene copolymer (RJ500) (% by weight) 99.5 - - - 99.5 - Ethylene-propylene block copolymer (CS500) (% by weight) - 99.5 - - - 99.5 Propylene Homopolymer (HJ700) (wt%) - - 99.5 99.5 - - Amine light stabilizer (wt%) 0.1 0.1 0.1 0.1 0.1 0.1 Biphenol-based antioxidant (wt%) 0.1 0.1 - 0.1 - - Phenolic antioxidant (% by weight) - - 0.1 - 0.1 0.1 Nucleating agent (% by weight) 0.2 0.2 0.2 0.2 0.2 0.2 Catalyst residue neutralizer (% by weight) 0.1 0.1 0.1 0.1 0.1 0.1 Melt Index [230 ℃] (g / 10min) 10 10 10 10 10 10 Tensile Strength (kg / ㎠) Before gamma irradiation 330 280 380 380 330 280 After gamma irradiation 330 280 350 360 320 280 Tensile Elongation (%) Before gamma irradiation > 600 > 600 500 500 > 600 > 600 After gamma irradiation > 600 > 600 310 460 > 600 > 600 Cloudiness (%) Before gamma irradiation 28 15 50 51 30 15 After gamma irradiation 29 15 54 54 32 16 Yellow road Before gamma irradiation 5 One 5 5 5 One After gamma irradiation 6 One 14 7 11 3

As can be seen in Table 1, the resin composition of the present invention exhibits excellent gamma-ray resistance such as physical property of the resin does not occur even after gamma-ray irradiation, transparency is maintained, discoloration is suppressed, and in particular, radiation is irradiated. It is suitable to be used as a material for various medical instruments to be sterilized.

Claims (5)

Melt index at 230 ° C. is 0.1-20 g / 10 min, ethylene content is 0.5-50% by weight, 65-95% by weight of crystalline ethylene-propylene random copolymer component and 5-35% by weight of elastic ethylene-propylene copolymer component 95% to 99.9% by weight of an ethylene-propylene block copolymer having an isotactic index value of 92 to 97.7%, an amine light stabilizer and 0.01 to 1% by weight of a nonphenolic antioxidant. Gamma-resistant ethylene-propylene copolymer resin composition which consists of. delete The method of claim 1, wherein the crystalline ethylene-propylene random copolymer component has an ethylene content of 0.5 to 15% by weight, the elastic ethylene-propylene copolymer component has an ethylene content of 20 to 70% by weight and an absolute viscosity of 0.5 to 1.5 dl / g, gamma-resistant ethylene-propylene copolymer resin composition. The gamma-ray-resistant ethylene-propylene copolymer resin composition according to claim 1, wherein the non-phenolic antioxidant is a hardoxyamine-based compound. The method of claim 1, 3 or 4, wherein the aluminum hydroxy di-tert-butyl benzoate, sodium 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate And one or two or more kinds of nucleating agents selected from benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, or 3,4-dimethylbenzylidene sorbitol by an amount corresponding to 0.01 to 1% by weight of the total resin composition. A gamma-resistant ethylene-propylene copolymer resin composition, characterized by the above-mentioned.