KR20070033203A - Transparent multi-layered container manufactured from resin compound with excellent transparency and impact resistance - Google Patents

Abstract

A transparent multi-layered container made of resin with excellent transparency and impact resistance is provided to keep good transparency after sterilization by steaming, to remove eluate, and to secure good impact resistance. The transparent multi-layered container is composed of inner and outer layers containing ethylene-propylene copolymer resin; a middle layer containing ethylene-vinyl alcohol copolymer, polyester, or polyamide; and adhesive layers formed between the inner and outer layers and between the middle and outer layers. The ethylene-propylene copolymer resin is ethylene-propylene random copolymer resin containing ethylene of 0.5~15.0wt.% or ethylene-propylene random-block copolymer resin consisting of an ethylene-propylene random copolymer part of 65~95wt.% containing ethylene of 0.5~15.0wt.% and an ethylene-propylene block copolymer part of 5~35wt.% containing ethylene of 20~70wt.%.

Description

TRANSPARENT MULTI-LAYERED CONTAINER MANUFACTURED FROM RESIN COMPOUND WITH EXCELLENT TRANSPARENCY AND IMPACT RESISTANCE}

The present invention relates to a transparent multilayer container made of a resin having excellent transparency and impact resistance. More specifically, transparency, impact resistance and storage stability are characterized by using ethylene-propylene copolymer resin for the inner layer and the outer layer, and comprising the ethylene-vinyl alcohol copolymer, polyester or polyamide as an intermediate layer. It relates to the transparent multilayer container secured.

In order to be used as a container for fruit storage, first, it must be transparent enough to check the contents, and second, mechanical properties of the container are maintained through sterilization before and after, and third, securing impact resistance properties that are not damaged during handling / movement / use. shall.

In the storage of fruits that require freshness such as pineapple and orange, most of them have been manufactured using aluminum / iron cans or glass so far to avoid deterioration of contents during storage. However, the can container has a problem in that it is difficult to grasp the contents of the product to reduce the value of the product, and in the case of the glass container, there is a high risk of breakage during transportation and use, and replacement with other materials is required.

Among the polymer resins, polypropylene can be prepared transparently by using a copolymerization technique. Since the melting temperature is 145 ° C. or higher, the polypropylene is excellent in deformation stability even at 120 ° C. under steam sterilization, and is suitable for food containers because it is harmless to humans. Therefore, when used with a gas barrier (gas barrier) material can be used for long-term food storage.

In the present invention, the ethylene-propylene copolymer resin is used for the inner layer and the outer layer, and the ethylene-vinyl alcohol copolymer is formed as the intermediate layer, so that transparency after steam sterilization is maintained, there is no eluate, and excellent impact resistance. It is an object to provide a transparent multilayer container.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention is an inner layer and an outer layer made of ethylene-propylene copolymer resin; An intermediate layer comprising one of an ethylene-vinyl alcohol copolymer, polyester and polyamide; And a bonding layer between the inner layer and the intermediate layer and between the intermediate layer and the outer layer.

In the transparent multilayer container of the present invention, ethylene-propylene random copolymer resin or ethylene-propylene random-block copolymer resin may be mentioned as the ethylene-propylene copolymer resin contained in the inner layer and the outer layer.

In the case of the ethylene-propylene random copolymer resin, the ethylene content is preferably 0.5 to 10% by weight. If the content is less than 0.5% by weight, the degree of crystallinity of the copolymer is higher than necessary to reduce the transparency of the resulting composition. If it exceeds 10% by weight, the transparency is sharply improved, but the heat resistance is poor, which is not suitable as a general container material.

The ethylene-propylene random copolymer resin may be used alone in the inner layer and the outer layer, or may be used by blending 1 to 25% by weight of metallocene polyethylene, when the metallocene polyethylene is blended, If the content is less than 1% by weight, the impact resistance deteriorates. If the content is more than 25% by weight, the heat resistance and the transparency are lowered.

In addition, the ethylene-propylene random-block copolymer resin is 65 to 95% by weight of ethylene-propylene random copolymerization part having an ethylene content of 0.5 to 15.0% by weight, and ethylene-propylene block copolymerization part having an ethylene content of 20 to 70% by weight. It is preferable that it consists of 5 to 35 weight%. If the ethylene-propylene random copolymerization portion is less than 65% by weight or the ethylene-propylene block copolymerization portion is more than 35% by weight, mechanical properties such as strength are lowered, and the ethylene-propylene random copolymerization portion is more than 95% by weight If the ethylene-propylene block copolymerization portion is less than 5% by weight, the impact resistance is lowered, which is not preferable.

In addition, in the ethylene-propylene random-block copolymer, when the ethylene content of the ethylene-propylene random copolymer portion is less than 0.5% by weight, the degree of crystallinity of the copolymer becomes higher than necessary, thereby lowering the transparency of the resulting composition. , When it exceeds 15.0% by weight, the heat resistance is poor, so it is not suitable as a material for food containers, and when the ethylene content of the ethylene-propylene block copolymerization portion is less than 20% by weight, the elasticity of the copolymer decreases and the impact resistance is lowered. When it exceeds 70 weight%, mechanical properties, such as strength, fall, and are unpreferable.

The ethylene-propylene random-block copolymer resin first forms an ethylene-propylene random copolymerization portion by simultaneously introducing ethylene and propylene into the polymerization reactor, and additionally forms the ethylene-propylene block copolymerization portion in addition to the formed ethylene-propylene random copolymerization portion. As further formed, two polymerizations are made by sequentially proceeding in one reactor. Specifically, ethylene and propylene are simultaneously introduced into the polymerization reactor to form an ethylene-propylene random copolymerization portion having an ethylene content of 0.5 to 15.0% by weight first, and in the following series of reactions, the formed ethylene-propylene random copolymerization portion is formed. By further forming an ethylene-propylene block copolymerization portion having an ethylene content of 20 to 70% by weight, an ethylene-propylene random-block copolymer resin is finally produced.

The absolute viscosity of the ethylene-propylene random-block copolymer resin is preferably 0.5 to 2.5 dl / g. When the absolute viscosity is less than 0.5dl / g, the dispersibility is good immediately after the processing and molding of the composition, but as the crystallization of the ethylene-propylene random copolymerization proceeds, a phenomenon occurs that the block copolymerization part seeps into the product surface. The transparency is lowered and the appearance of the product is greatly damaged. On the other hand, when the absolute viscosity is greater than 2.5 dl / g, the dispersibility of the elastomeric copolymer component during molding of the composition is lowered and transparency is reduced.

In the transparent multilayer container of the present invention, 1 to 25 parts by weight of styrene-ethylene-butylene-styrene terpolymer may be further included with respect to 100 parts by weight of the ethylene-propylene copolymer resin contained in the inner layer and the outer layer. . If the content of the terpolymer is less than 1 part by weight, the expected effect may not be obtained by further including the terpolymer, and if the content of the terpolymer exceeds 25 parts by weight, the terpolymer is inexpensive due to the high cost.

In addition, in the transparent multilayer container of the present invention, the inner layer and the outer layer may further include 0.01 to 1.0 parts by weight of a nucleating agent based on 100 parts by weight of the resin component constituting the respective layers in order to improve the transparency of the container. have. When the content of the nucleating agent is less than 0.01 part by weight, the transparency of the film is not satisfactory, and when the content of the nucleating agent is more than 1 part by weight, the mechanical properties of the container are lowered.

As the nucleating agent, sorbitol-based nucleating agents such as benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol and 3,4-dimethylbenzylidene sorbitol, aluminum-based nucleating agents such as aluminum hydroxy-di-t-butylbenzoate, sodium 2 At least one selected from the group consisting of sodium-based nucleating agents such as 2'-methylenebis (4,6-di-t-butylphenyl) phosphate may be used.

In the transparent multilayer container of the present invention, in order to impart gas barrier properties to the intermediate layer, ethylene-vinyl alcohol copolymer, polyester or polyamide is used, and the adhesion between the polymers and the ethylene-propylene copolymer resin Since it is not good, a bonding layer is used between each layer. The bonding layer is a polypropylene grafted with an acid anhydride, such as maleic anhydride, which is adhesive with an ethylene-vinyl alcohol copolymer, polyester or polyamide used as the intermediate layer, and is also adhesive with polypropylene. (anhydride grafted polypropylene) or ethylene vinyl acetate copolymer (anhydride grafted ethylene vinyl acetate) and the like can be used.

In the transparent multi-layered container of the present invention, each layer includes an antioxidant, a catalyst residue neutralizing agent (hereinafter, 'catalyst neutralizing agent'), in addition to the above components, in order to prevent the degradation of physical properties during processing, sterilization, movement and transport. And an additive such as an anti-slip agent or an anti-blocking agent, and when the additive is added, its type and content may be used as known in the art.

For example, tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrosilylate as an antioxidant used to prevent eluate generation and physical property degradation by high temperature / high pressure steam sterilization ) And phenolic antioxidants such as 1,3,5-trimethyl-tris (3,5-di-t-butyl-4-hydroxybenzene), and tris (2,4-di-t-butylphenol) force It is preferable to use 0.01-0.5 weight part with respect to 100 weight part of resin components which are selected from the group which consists of phosphite type antioxidants, such as a pit, and comprises each layer.

In addition, the catalyst neutralizing agent that can be used in the present invention is added to neutralize the catalyst used in the synthesis of the polymer when it remains in the polymer and remains as a catalyst residue, and is based on 100 parts by weight of the resin component constituting each layer. It is preferable to use 0.01-0.5 weight part, and the catalyst neutralizing agent generally used in a resin composition can be used. Preferred catalytic neutralizing agents include calcium stearate or synthetic hydrotalcite.

In the transparent multilayer container of the present invention, the melt index of each layer is preferably in the range of 0.5 to 10 g / 10 minutes under a load of 230 ° C. and 2.16 kg, and the melt index is less than 0.5 g / 10 minutes or 10 g / 10. If it is more than minutes, workability will fall and the surface characteristic and transparency of a transparent multilayer container will worsen.

In the transparent multi-layered container of the present invention, the manufacturing process first produces a resin composition constituting each layer, and then the resin composition is extruded blown, injection blowed, injection stretch blow It is possible to produce a five-layer container having an inner layer, an outer layer, an intermediate layer, and a bonding layer between each layer by a conventional multilayer blow manufacturing method.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to Examples.

[ Example ]

For Examples 1 to 2 and Comparative Examples 1 to 2, the raw material components were mixed with the ingredients and contents shown in Table 1, and then melt mixed through a twin screw extruder to pelletize the resin compositions. It was. Melt index was measured using the prepared pellets, and the results are shown in Table 1.

The resin compositions obtained above are applied to an inner layer and an outer layer, an ethylene-vinyl alcohol copolymer is applied to an intermediate layer, and ethylene vinyl acetate in which maleic anhydride is grafted between the inner layer and the intermediate layer and between the intermediate layer and the outer layer. By applying a bonding layer made of a copolymer, a transparent multilayer container was produced by a blow molding method. Formability was observed during container molding, and the results are shown in Table 1.

In addition, the haze, the impact test result, the heat resistance at the steam sterilization condition were measured for the transparent multilayer container obtained as described above, and the measurement results are shown in Table 1.

Property measurement method

1) Melt index: measured at 230 ° C. and 2.16 kg based on ASTM D1238.

2) haze: Measured according to ASTM D1003.

3) Impact test: After freezing storage for 2 days at -20 ℃, the degree of cracking when falling at 2m height was measured. There was no break at all, or 90% or more of the specimens had no breakage, and the other case was "failure."

5) Heat resistance: It was judged by the deformation and cloudiness of the container after steam sterilization. "Good" is the case where there is no deformation and blurring of the container, and "normal" is the case where there is slight deformation of the deformation and the blurring degree of the container. .

6) Forming of container: After processing, it was judged as parison deflection, unformed part and surface of container. "Good" for parison deflection, no unformed part and smooth surface condition after operation, "normal" for parison deflection, unformed part and container surface condition slightly worse, otherwise Was taken as "bad".

                (Composition Unit: Weight%) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 PL only 100 95 EL-PL random 100 95 EL-PL random-block 100 Metallocene EL 5 5 Layered Inner layer-bonding layer-middle layer-bonding layer-outer layer Experiment result Melt Index (g / 10min) 2 2 2 2 2 Cloudiness (%) 30 35 37 75 75 Impact test Pass Pass Pass failure failure Heat resistance Great Great Great Great Great Container formability Great Great Great usually usually

1) PL alone: Propylene homopolymer (HF11HP, Samsung Total Co., Ltd.)

2) EL-PL random: ethylene-propylene random copolymer (RB200, ethylene 2.5% by weight, Samsung Total Co., Ltd.)

3) PL-EL random-block: ethylene-propylene random-block copolymer (CS200, total ethylene 8.0% by weight (ethylene-propylene random copolymerization part) Ethylene content 2.0% by weight, ethylene content in the ethylene-propylene block copolymerization part 40% by weight), Samsung Total Co., Ltd.)

4) Metallocene EL: Ethylene copolymer made of metallocene catalyst (Mitsui)

As can be seen in Table 1, the transparent multilayer containers of Examples 1 to 3 were excellent in container formability, transparency, impact resistance, heat resistance, etc., in particular, to improve the value of the final product due to its excellent transparency and heat resistance. Suited.

As described above, according to the present invention, a transparent multilayer container having characteristics that are economical, transparent, and excellent in impact resistance can be obtained.

Claims (9)

An inner layer and an outer layer comprising ethylene-propylene copolymer resin; An intermediate layer comprising an ethylene-vinyl alcohol copolymer, polyester or polyamide; And a bonding layer between the inner layer and the intermediate layer and between the intermediate layer and the outer layer. The ethylene-propylene copolymer resin according to claim 1, wherein the ethylene-propylene copolymer resin is an ethylene-propylene random copolymer resin having an ethylene content of 0.5 to 15.0% by weight, or an ethylene-propylene random copolymer part 65 to 95 having an ethylene content of 0.5 to 15.0% by weight. A transparent multilayer container, characterized in that the ethylene-propylene random-block copolymer resin consists of 5% to 35% by weight of an ethylene-propylene block copolymerization portion having a ethylene content of 20 to 70% by weight. The transparent multilayer container according to claim 1 or 2, wherein the inner layer and the outer layer are formed by blending 1 to 25% by weight of polyethylene made of a metallocene catalyst with ethylene-propylene random copolymer resin. . The method according to claim 1 or 2, wherein the inner layer and the outer layer is 1 to 25 parts by weight of styrene-ethylene-butylene-styrene terpolymer further comprises 100 parts by weight of the ethylene-propylene copolymer resin The transparent multilayer container characterized by the above-mentioned. The transparent multilayer container according to claim 1 or 2, wherein the inner layer and the outer layer further comprise 0.01 to 0.5 parts by weight of a nucleating agent based on 100 parts by weight of the ethylene-propylene copolymer resin. 6. The transparent multilayer container of claim 5, wherein the nucleating agent is selected from the group consisting of a sorbitol nucleating agent, an aluminum nucleating agent, and a sodium nucleating agent. The transparent multilayer container according to claim 1 or 2, wherein the bonding layer is a polypropylene or ethylene vinyl acetate copolymer grafted with an acid anhydride. The transparent multilayer container according to claim 1 or 2, wherein each layer further comprises 0.01 to 0.5 parts by weight of antioxidant and 0.01 to 0.5 parts by weight of catalyst neutralizing agent based on 100 parts by weight of the resin component constituting each layer. The transparent multilayer container according to claim 1 or 2, wherein the melt index of the inner layer, the outer layer and the intermediate layer is in the range of 0.5 to 10 g / 10 minutes under a load of 2.16 kg at 230 ° C.