KR100314827B1 - Oxygen barrier resin composition and product containing the same - Google Patents

Abstract

The present invention relates to an oxygen-blocking resin composition and a product containing the same, and more particularly, a) 20 to 80 weight of ethylene-vinyl alcohol copolymer, b) 5 to 79 weight of ethylene copolymer and c) ethylene-anhydride An oxygen-blocking resin composition comprising a random copolymer of maleic acid-alkyl (meth) acrylate and a reactant of 1 to 30% by weight of a polyamide oligomer having a molecular weight of about 1,000 to 5,000. Since the composition according to the present invention has excellent meltability and compatibility at the same time, the product using the composition as a barrier layer has excellent appearance (transparency, etc.), mechanical strength and oxygen barrier property.

Description

Oxygen barrier resin composition and product containing the same

The present invention relates to an oxygen barrier resin composition and a product containing the same, and more particularly, using a mixture of an ethylene-vinyl alcohol copolymer (hereinafter referred to as 'EVOH') and an ethylene copolymer, The present invention relates to a resin composition capable of producing a film, a sheet, a container having excellent mechanical properties and appearance, and an article including at least one layer composed of the composition.

Polyolefin resins such as polyethylene and polypropylene are widely used for various purposes because of their excellent moldability, mechanical properties, and moisture barrier properties.However, due to their high gas permeability, such as those for food packaging requiring oxygen and gas barrier properties. The use is limited to the use. For this reason, polyolefin resins are manufactured as food packaging films, sheets or containers having a multilayer structure by coextrusion, lamination or coating with EVOH, which is a polymer having excellent oxygen barrier property.

On the other hand, EVOH is a resin excellent in gas barrier properties and transparency, and is widely used as a resin for gas barrier layers when manufacturing multilayer molded articles, but its use is limited because the price is much higher than that of polyolefin. In this regard, the thickness of the multilayer molded article can be lowered by making the thickness of the EVOH layer as thin as possible. However, the thinning of the EVOH layer below a certain thickness has a great restriction in maintaining the uniformity of the molded article.

For this reason, a method of mixing EVOH with low-cost polyethylene is known as a method of lowering the price of the gas barrier layer. However, when preparing the composition for this purpose, it is difficult to prepare the two mixtures due to the lack of compatibility between EVOH and polyethylene, uneven appearance of the film or sheet using these mixtures as a barrier layer, and low mechanical strength. There is a problem. Therefore, when preparing the mixture, it is common to mix the compatibilizer components together as a third component in order to increase the compatibility of the EVOH and polyethylene, and the selection of the compatibilizer for making a composition having excellent mechanical strength and appearance of the molded article is difficult. It has been a major technical challenge.

For example, European Patent Nos. 15,556 (1980) and 210,725 (1987), US Pat. No. 4,971,864 (1990) and US Pat. No. 5,356,990 (1994) include compounds having polar groups such as maleic anhydride in polyethylene. It is disclosed that a film having improved oxygen barrier properties and mechanical properties can be prepared by using a graft polymerized compatibilizer. However, the barrier resin composition according to the above methods still has poor appearance such as transparency and thickness deviation of the molded article, and when the content of the compatibilizer is increased to increase the compatibility, the meltability is lowered and the oxygen barrier property is also increased. There are many problems that make it difficult to commercialize.

Accordingly, an object of the present invention is to provide an oxygen-blocking resin composition having excellent compatibility between the two resins in mixing EVOH and an ethylene copolymer, as well as excellent melt formability and excellent appearance and mechanical strength of the molded article. .

Another object of the present invention to provide a product comprising at least one layer of the resin composition.

The resin composition of the present invention for achieving the above object is a random copolymer of 20 to 80 weight of EVOH, 5 to 79 weight of ethylene copolymer and ethylene-maleic anhydride-alkyl (meth) acrylate and molecular weight of about 1,000 to 5,000 It consists of 1-30 weights of reactants of polyamide oligomer.

The product of the present invention for achieving the above another object is an oxygen barrier film or sheet comprising at least one layer of the composition.

Looking at the present invention in more detail as follows.

As described above, the present invention comprises a) a random copolymer of 20 to 80 weights of EVOH, b) 5 to 79 weights of ethylene copolymer, and c) ethylene-maleic anhydride-alkyl (meth) acrylate and a molecular weight of 1,000 to It consists of 1-30 weight of reactants of about 5,000 polyamide oligomer.

In the present invention, the EVOH is used alone or mixed with a copolymer of ethylene-vinyl alcohol obtained by saponifying ethylene-vinylacetate produced by copolymerization of ethylene and vinyl acetate. At this time, when the degree of saponification of the EVOH is less than 90, oxygen barrier property is not sufficient, and the higher the degree of saponification, the better the oxygen barrier property. In addition, when the ethylene content of EVOH is less than 10 moles, the workability is poor and melt molding is difficult, and when it exceeds 50 moles, the oxygen barrier property is not sufficient.

The ethylene copolymer is a linear low density polyethylene, preferably air of ethylene and α-olefin and copolymer (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), ethylene-vinylacetate copolymer and ethylene-unsaturated acid derivative. One or more mixtures selected from the group consisting of coalescing are used. The α-olefin is an α-olefin having 4 to 8 carbon atoms, at least one selected from the group consisting of butene-1, hexene-1, 4-methylpentene-1, and octene-1, and the unsaturated acid derivative is ( One or more are selected from the group consisting of methacrylic acid and alkyl (meth) acrylates.

The c) component is used as a compatibilizer component to increase the compatibility of the EVOH and the ethylene copolymer, polyamide oligomer 2 to 50 to 98 parts by weight of a random copolymer of ethylene-maleic anhydride-alkyl (meth) acrylate It can be prepared by melting and extruding by mixing -50 parts by weight. At this time, if the amount of the random copolymer of ethylene-maleic anhydride-alkyl (meth) acrylate is less than 50 parts by weight, an excessive amount of unreacted polyamide oligomer is present in the morphology and meltability of the composition. Oxygen permeability is rather lowered as it affects, and when it exceeds 98 parts by weight, the reaction with the polyamide oligomer does not sufficiently occur, so the effect of the present invention is not large. Here, it is judged that the part where the reaction proceeds is mainly an amine group which is an end group of the polyamide oligomer and an anhydride group of the ethylene-maleic anhydride-alkyl (meth) acrylate random copolymer, and the reaction is excellent in the present invention. It is believed that a compatibilizer is prepared. The compatibilizer thus prepared is in the form of a copolymer of ethylene-alkyl (meth) acrylate in which the main chain of polyamide is grafted instead of maleic anhydride. It is judged that it penetrates into the phase of EVOH and the main chain of ethylene-alkyl (meth) acrylate plays a role as a compatibilizer by penetrating onto the ethylene copolymer. In addition, this method minimizes the direct reaction between the compatibilizer and EVOH by modifying the maleic anhydride group which can react directly with EVOH, thereby inhibiting crosslinking reaction in the composition to the maximum, thereby forming meltability, appearance and mechanical properties of the molding. It seems to be excellent.

In the ethylene-maleic anhydride-alkyl (meth) acrylate random copolymer, the alkyl group means a hydrocarbon compound having 1 to 12 carbon atoms, and one or more thereof may be mixed and used. These copolymers can be produced by radical copolymerization of ethylene with maleic anhydride, which is a comonomer, and an alkyl (meth) acrylate.

At this time, the polymerization ratio of ethylene and the comonomer can be controlled, and in the copolymer suitable for use in the present invention, the weight ratio of the comonomer is 0.1 to 10 parts by weight of maleic anhydride, alkyl (meth) acrylrel About 3-30 weight part of wits are suitable. Maleic anhydride is an important functional group for causing a reaction with the polyamide oligomer in the present invention, when the content is less than 0.1 part by weight in the copolymer, the effect of the present invention is less likely to occur, and when it exceeds 10 parts by weight, the composition of the present invention. The crosslinking reaction tends to occur at the time of preparation, so that the meltability is deteriorated, so that the appearance of the molded product is deteriorated. On the other hand, alkyl (meth) acrylate not only improves the transparency by reducing the degree of crystallinity of the copolymer, but also has a lower melting temperature, so that the prepared compatibilizer has good flowability when melting in the composition excellent compatibility To indicate. In the present invention, when the content of the alkyl (meth) acrylate is less than 3 parts by weight, it is difficult to obtain such an effect, and when it exceeds 30 parts by weight, the prepared compatibilizer becomes poor in compatibility with the ethylene copolymer, and thus the effect as a compatibilizer Very low. (Illustrative examples of the copolymers that can be used currently for commercial may include Elf Atochem's Lotader ^R or Japan Polyolefin Corporation Adtex ^R.)

The polyamide may be selected from the group consisting of polyamide-6, polyamide-6 / 66, polyamide-12, and polyamide-6 / 12, wherein the polyamide oligomer is a primary amine in the process of preparing polyamide. It can be prepared by adding a molecular weight regulator such as. In the present invention, polyamide oligomers having a molecular weight of about 1,000 to 5,000 are mainly used. In this case, when the molecular weight of the polyamide exceeds 5,000, since there are less amine groups at the terminal and the flowability is poor during melt extrusion, the reaction with the copolymers containing maleic anhydride is less likely to occur. Same effect as in In addition, if the molecular weight of the polyamide is too small, less than 1,000, the reaction between the two components is less likely to occur when mixing with the ethylene-maleic anhydride-alkyl (meth) acrylate copolymer is not well mixed.

The composition according to the present invention may be mixed into an extruder after dry blending or melt blending according to the manufacturing conditions of the product, and then manufactured into a molding.

The composition of the present invention can be processed using processing equipment such as blown, cast extrusion molding, and when the composition of the present invention is A, the adhesive resin is B, the thermoplastic resin is C, A layer alone or A / B, A / B / C, B / A / B, C / B / A / B / C, C / A / C / B / C, C / B / C / A / C / It can be made into a multilayer film, sheet or container having various structures such as B / C. Representative adhesive resins may be used in which a polyolefin resin such as polyethylene or polypropylene is grafted with an unsaturated acid such as maleic acid. In the multilayer structure described above, typical thermoplastic resins include polyethylene, polypropylene, polystyrene, polyamide, and the like.

The composition of the present invention may be used additives such as processing aids, dyes, antioxidants, light stabilizers, plasticizers, if necessary, in particular when adding a plasticizer for EVOH, such as glycerol, p-toluenesulfonamides It can improve flexibility.

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

Oxygen barrier properties of all samples were measured using a gas permeability meter (Model name: Toyoseiki MC1, B-Type) after leaving them in a humid condition at a temperature of 23 ° C. and a relative humidity of 50 for 1 day. The unit of oxygen permeability is cc / m 2 · day · atm. Haze was measured using a haze meter (300A Turbidimeter by Nippon Denshoku) and the unit is.

The melt index of each resin was measured by applying a force of 2160 g at 190 ° C or 210 ° C by ASTM D1238, and the unit was g / 10 min. The density of each resin was measured by ASTM D-1505 method, and the unit is g / cm 3.

The types of EVOH and ethylene copolymers used in the experiment are shown in Table 1 below.

ingredient Resin Type Melt Accuracy (2,160g, g / 10min) 190 ℃ 210 ℃ EVOH E-1 44 mol of ethylene - 13 E-2 32 mol of ethylene - 12 Ethylene Copolymer P-1 Linear Low Density Polyethylene (LLDPE) 0.7 - P-2 Linear Low Density Polyethylene (LLDPE) 1.0 - P-3 Ethylene-vinylacetate copolymer (vinyl acetate content 15 weights) 1.5 -

The kind of c) component used for the experiment is shown in Table 2 below.

ingredient Resin type Melt viscosity Density (g / cm 3) 190 ℃ C-1 Ethylene-maleic anhydride-methylacrylate random copolymer ¹⁾ 10.9 0.937 C-2 Ethylene-maleic anhydride-methylacrylate random copolymer ²⁾ 13.7 0.935 C-3 Ethylene-maleic anhydride-butylacrylate random copolymer ³⁾ 7.6 0.943 C-4 Linear low density polyethylene polymerized with maleic anhydride ⁴⁾ 1.5 0.919 PAO Polyamide-6, Molecular Weight 2,000 - - C-5 C-1 / PAO = 90/10 parts by weight of reactant 5.7 - C-6 C-1 / PAO = 80/20 parts by weight of reactant 2.5 - C-7 C-2 / PAO = 90/10 parts by weight of reactant 6.5 - C-8 C-2 / PAO = 80/20 parts by weight of reactant 2.7 - C-9 C-3 / PAO = 90/10 parts by weight of reactant 2.1 -

1) Adtex ^R ET 182 from Japan Polyolefin.

2) Adtex ^R ET 184M from Japan Polyolefin.

3) Adtex ^R ER 615F from Japan Polyolefin.

4) Lotader ^R 3410 from Elf Atochem.

Preparation of Polyamide Oligomers (PAO):

170 g of caprolactam (ε-Caprolactam), 10.9 g of dodecylamine and 3.9 g of water were sealed in a 500 ml pressurized reactor, and reacted with stirring at 260 ° C. for 2 hours. At this time, the pressure of the pressure reactor increased to 4.5 kg / ㎠. The pressure control valve was opened to normal pressure, and then reacted at 260 ° C. for 2 hours, and then the temperature was lowered to room temperature to obtain a solid component. The solid components were pulverized in a pulverizer, made into a powder, put into boiling water, stirred for 2 hours, filtered, and dried in a vacuum oven at 80 ° C. for 8 hours. The melting temperature of the polyamide oligomer obtained as a result of the measurement by the thermal analysis equipment was 220 degreeC.

Preparation of Compatibilizers C-5 to C-9 of the Invention:

After dry blending with each weight part described in Table 2, pellets were melt-extruded at 130-180-210-220-210 ° C using a twin screw extruder having a diameter of 19 mm. pallet).

Examples 1-5 and Comparative Examples 1-5

E-2 50 weights, P-1 40 weights, and 10 weights of compatibilizers, respectively, in a total amount of 2 kg each dry mixed using a tumble mixer, and then the mixture was 190-200-210-210 using a twin screw extruder with a diameter of 19 mm. Pellets were prepared by melt extrusion at −210 ° C. FIG. After drying the prepared pellets at 60 ℃ for 12 hours, using a five-layer casting film equipment using a barrier film to prepare a five-layer film having a structure of polyethylene / adhesive layer / barrier layer / adhesive layer / polyethylene. In this case, the polyethylene is a linear low density polyethylene having a melt index of 2.8 (190 ° C., 2.16 kg) and a maleic anhydride modified (graft) linear low density polyethylene having a melt index of 3.5 (190 ° C., 2.16 kg) as an adhesive layer (MAH-g -LLDPE) was used. Each layer was prepared to have a thickness of 30/10/15/10/30 μm. The results are shown in Table 3 below.

Compatibilizer Barrier Layer Pellets 5-layer film properties Melt Index (190 ℃, 2.16㎏) Thickness deviation Haze Oxygen transmittance (cc / ㎡. Day. Barometric pressure) Example 1 C-5 1.06 ○ 12 2.8 Example 2 C-6 1.50 ○ 13 2.0 Example 3 C-7 1.20 ◎ 13 1.8 Example 4 C-8 1.60 ○ 14 1.7 Example 5 C-9 0.36 ◎ 11 2.5 Comparative Example 1 C-1 0.08 × 16 2.9 Comparative Example 2 C-2 0.11 × 17 2.7 Comparative Example 3 C-3 0.04 × 30 3.8 Comparative Example 4 C-4 1.00 △ 22 3.1

* ◎; Within ± 10, ○; ± 10-15, △; ± 15-20, ×; ± 20 or more

As shown in the above Examples and Comparative Examples, the composition of the present invention is excellent in the melt-molding can be produced a film excellent in thickness deviation and transparency (low haze), it can be seen that also excellent oxygen barrier properties.

Examples 6-9 and Comparative Examples 5-7

The EVOH, compatibilizer and ethylene copolymer were dry mixed using a tumble mixer in a total amount of 20 kg each in the weight ratios shown in Table 4 below, and then the mixture was mixed with a 3-layer blown film machine manufactured by Kiefel, Germany. Company name: Rotex 40S / 30S / 40S) into the middle layer extruder, and inside and outside extruder, the adhesive resin maleic anhydride-graft-polyethylene is added to the width A three-layer film of 500 mm and a thickness of 55 µm was prepared. In this case, a screw having a screw compression ratio of 3.3: 1 was used, and the temperature of the interlayer extruder was maintained at 210 ° C. The average thickness of each layer was 20/15/20 µm as measured by an electron microscope (Shimen 515 SEM).

Each weight ratio of EVOH / compatibilizer / polyethylene Haze () Oxygen transmittance (cc / ㎡. Day. Barometric pressure) Example 6 E-2 / C-5 / P-1 = 60/7/33 11.2 2.0 Example 7 E-1 / C-8 / P-1 = 60/10/30 9.4 12.5 Example 8 E-2 / C-8 / P-1 = 50/7/43 12.8 4.9 Example 9 E-2 / C-9 / P-2 = 60/5/35 11.6 2.3 Comparative Example 5 E-2 / C-1 / P-1 = 60/5/35 23.6 10.1 Comparative Example 6 E-1 / C-2 / P-1 = 60/10/30 27.5 45.4 Comparative Example 7 E-2 / C-4 / P-2 = 60/7/35 27.3 12.5

As shown in the above Examples and Comparative Examples, when the blown film is prepared using the composition of the present invention as a barrier layer, not only the transparency but also the oxygen barrier property is excellent.

Examples 10-11 and Comparative Examples 8-9

EVOH, ethylene copolymer and compatibilizer were dry mixed using a tumble mixer in a total amount of 50 kg each at a weight ratio shown in Table 5 below, and then the mixture was 190-200-210-210 using a twin screw extruder having a diameter of 40 mm. Pellets were prepared by melt extrusion at −210 ° C. FIG. The prepared pellets were dried at 60 ° C. for 12 hours and then five air-cooled blown films with five extruders (A / B / C / D / E) each 50/50/60/50/60 mm in diameter. It was put in the C-extruder of the extruder to prepare a film having a width of 1,200 mm.

Layers A and E: linear low density polyethylene (melt index 1.0, density 0.919)

Layers B and D: Maleic Acid Modified Linear Low Density Polyethylene (MI 1.2, Density 0.90)

Processing temperature; -A, B, D, E Extruder: 190-200-210-215 ℃

C extruder: 200-210-215-220 ℃

Adapter: 225 ℃

-Die: 220 ℃

Extrusion amount; 200 kg / hour

The film thickness was made into 62 micrometers with A / B / C / D / E being 15/10/12/10/15 micrometers, respectively.

Each weight ratio of EVOH / compatibilizer / ethylene copolymer Haze Oxygen transmittance (율 / ㎡, work, atmospheric pressure) Tensile Strength at Break (㎏ / ㎠) (ASTM D638) Example 10 E-2 / C-8 / P-1 = 60/7/33 12.6 2.7 218/175 Example 11 E-1 / C-9 / P-2 = 50/10/30 13.4 15.3 210/184 Example 12 E-2 / C-5 / P-3 = 60/7/33 10.5 3.4 223/190 Comparative Example 8 E-2 / C-2 / P-1 = 60/7/33 30.5 25.8 169/113 Comparative Example 9 E-1 / C-3 / P-2 = 50/10/30 33.2 83.2 185/117 Comparative Example 10 E-2 / C-1 / P-3 = 60/6/34 25.3 11.2 206/115

As shown in the above Examples and Comparative Examples, when the compatibilizer of the present invention is used, a mixed composition of EVOH and an ethylene copolymer which can be used as an oxygen barrier layer of a film excellent in appearance, oxygen barrier property and mechanical strength is prepared. It can be seen that.

As described above, since the resin composition using the compatibilizer of the present invention has excellent meltability and compatibility at the same time as the conventional compatibilizer, the molded article using the composition according to the present invention as a barrier layer. It is possible to produce a film or sheet excellent in appearance (transparency, etc.), mechanical strength and oxygen barrier property.

Claims (12)

a) 20 to 80 weights of ethylene-vinyl alcohol copolymer, b) 5 to 79 weights of ethylene copolymer, and c) a random copolymer of ethylene-maleic anhydride-alkyl (meth) acrylate and a polyolefin having a molecular weight of about 1,000 to 5,000. An oxygen barrier resin composition comprising 1 to 30 wt% of a reactant of an amide oligomer. The resin composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer is a resin obtained by saponifying at least 90 or more of the ethylene-vinylacetate copolymer having a ethylene content of 10 to 50 mol. The resin of claim 1, wherein the ethylene copolymer is selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene-vinylacetate copolymer and copolymers of ethylene-unsaturated acid derivatives. Composition. The resin composition according to claim 3, wherein the linear low density polyethylene is a copolymer of ethylene and α-olefin. The resin composition according to claim 1, wherein the reaction ratio of the random copolymer of ethylene-maleic anhydride-alkyl (meth) acrylate and the polyamide oligomer is 98: 2 to 50:50 parts by weight. The resin composition according to claim 1 or 5, wherein the alkyl (meth) acrylate is selected from the group consisting of (meth) acrylates having an alkyl group having 1 to 12 carbon atoms. The resin composition according to claim 4, wherein the α-olefin is selected from the group consisting of butene-1, hexene-1, 4-methylpentene-1 and octene-1. The resin composition according to claim 3, wherein the unsaturated acid derivative is selected from the group consisting of (meth) acrylic acid and alkyl (meth) acrylate. The resin of claim 1, wherein the polyamide oligomer is selected from the group consisting of polyamide-6, polyamide-6 / 66, polyamide-12, and polyamide-6 / 12 oligomers. Composition. An oxygen barrier film comprising at least one layer of the composition of claim 1. An oxygen barrier sheet comprising at least one layer of the composition of claim 1. An oxygen barrier container comprising at least one layer of the composition of claim 1.