KR20080046911A - Oxigen barrier resin composition comprising ethylene-acrylate copolymer and articles therefrom - Google Patents

Abstract

An oxygen barrier resin composition, and an oxygen barrier film and an oxygen barrier container comprising the composition are provided to improve melt molding property, compatability, transparency and oxygen barrier property. An oxygen barrier resin composition comprises 40-90 wt% of an ethylene-acrylate copolymer comprising 10-50 mol% of ethylene and 50-90 mol% of acrylate; 5-55 wt% of a polyolefin; and 1-20 wt% of an ethylene-(meth)acrylic acid copolymer. Preferably the ethylene-(meth)acrylic acid copolymer has a mass average molecular weight of 30,000 g/mol or more; and the polyolefin is at least one selected from LLDPE, LDPE, HDPE, polypropylene, polybutene, polyhexene, polypentene and polyoctene.

Description

Oxygen barrier resin composition comprising ethylene-acrylate copolymer and product using same {OXIGEN BARRIER RESIN COMPOSITION COMPRISING ETHYLENE-ACRYLATE COPOLYMER AND ARTICLES THEREFROM}

The present invention relates to an oxygen barrier resin composition and an article comprising the same, in particular an oxygen barrier resin composition comprising a) an ethylene-acrylate copolymer, b) polyethylene, and c) an ethylene-acrylic acid copolymer and It relates to a produced film, a container and the like. The oxygen barrier resin composition according to the present invention is not only excellent in melt formability and compatibility, but also excellent in appearance (transparency and the like) and oxygen barrier property, and can be used for the production of films, sheets, containers, and the like.

In general, polyolefin resins such as polyethylene (PE) and polypropylene (PP) are used in various applications due to their excellent moldability, mechanical properties and moisture barrier properties. However, its specific use, such as for food packaging, has a high gas permeability, particularly an oxygen permeability, which limits its use. For this reason, a method of increasing the oxygen barrier property by compounding a nanocomposite in a polyolefin resin has been studied, but has a problem in that the barrier property is not improved and mechanical properties are inferior. In general, polyolefin resin is a food packaging film by producing a multilayer film through co-extrusion and lamination (ethylene vinyl alcohol (EVOH) copolymer, nylon, polyvinylidene chloride, etc.) having excellent oxygen barrier properties, It is used to manufacture a container and the like.

EVOH is a polymer material having excellent gas barrier properties and transparency, but is used in food or chemical packaging, but its use is limited because its price is extremely high and disadvantages in terms of flexibility and stretchability.

As described above, in order to overcome the low oxygen barrier property of the polyolefin resin and to impart flexibility and stretchability to the EVOH, a technique of blending the polyolefin resin and the EVOH is also known, but commercialization between the polyolefin resin and the EVOH is performed. There is a problem in that mechanical properties are inferior because of poor compatibility and a non-uniform mixture is obtained during film or sheet manufacture. Therefore, it is a major technical problem to select a suitable compatibilizer in the preparation of such a mixture to increase the uniformity of the mixture.

EP 0,015,556 (published Sep. 17, 1980) and 0,210,725 (published Feb. 04, 1987) and US Pat. No. 4,971,864 (registered Nov. 20, 1990) are compatibilizers in which a compound having a polar group is grafted onto polyethylene. It is disclosed that by using the film to improve the uniformity of the mixture of the polyolefin-based and EVOH to improve the oxygen barrier properties and mechanical properties. In addition, US Pat. No. 5,310,788 (registered May 10, 1994) discloses a reaction product of a polyolefin and a polyamide (or polyamide oligomer) in which a compound having a polar group is grafted onto polyethylene in order to increase the compatibility between polyolefin and EVOH. A method of improving the stretchability and flexibility of a mixture is disclosed. However, the film produced by the above patents, the melt moldability and oxygen barrier properties are lowered when the content of the compatibilizer is increased to increase the compatibility, and the transparency and mechanical properties of the film when the compatibilizer content is decreased There is a problem falling.

U.S. Patent No. 5,356,990 (registered on Oct. 18, 1994) discloses a technique for melting EVOH and adding an ethylene copolymer to improve the mechanical properties of EVOH and the appearance of the product. Equipment is required. In addition, Korean Patent Application No. 1996-001657 discloses a multilayer film in which a partial saponification resin of an ethylene-vinylacetate copolymer is mixed with a polyolefin resin and EVOH and then coated on both surfaces of the polyolefin resin using EV as a compatibilizer. There is a limit in compatibility between polyolefin-based resin and EVOH, and there is a need to manufacture a multilayer film.

Research into the film that can substantially solve this problem has been continued.

The technical problem to be achieved by the present invention is a resin composition which can be used in the manufacture of a film, sheet, container, etc., as well as excellent in meltability and compatibility, as well as excellent appearance (transparency, etc.) and oxygen barrier properties It is to provide a used product.

The present inventors have earned a lot of research to achieve the technical problem as described above, and succeeded in the production of a composition comprising a copolymer having a new component composition other than the EVOH-based mainstream of the prior art to complete the present invention It became.

The present invention provides an oxygen barrier resin composition comprising a) an ethylene-acrylate copolymer, b) a polyolefin, and c) an ethylene-acrylic acid copolymer. The resin composition provided by this invention is a) 40-90 weight% of ethylene-acrylate copolymers which consist of 10-50 mol% of ethylene and 50-90 mol% of acrylate; b) 5-55 weight percent polyolefin; And c) 1 to 20% by weight of ethylene-acrylic acid copolymer.

The present invention also provides an oxygen barrier film and a container comprising the resin composition according to the present invention.

As used herein, "copolymer" refers to a polymer made of two or more comonomers, and "comonomer" refers to monomers that make up the copolymer. In addition, the term "acrylate" in the "ethylene-acrylate copolymer" herein refers to acrylic acid compounds such as acrylic acid esters and acrylic acid salts inclusively. In addition, the term "film" as used in the present invention is a generic term that is made of a thin film form, it is a concept that includes all commonly called sheets (sheets), wrap (wrap).

As described above, in the prior art, a technique for improving physical properties by using a blending between a polyolefin and a polymer containing a polar group has been proposed, but in this case, problems of compatibility between resins and difficulty in selecting an appropriate compatibilizer are difficult. There was a technical limit to this. In addition, it has been a technical problem to solve the problem of uniformity of the film by applying a polyolefin containing a polar group to the barrier film without blending between resins. General methods for introducing polar groups into polyolefins include high temperature, high pressure, and catalytic methods, but difficulties in the manufacturing process and the amount of polar groups introduced are limited. However, the ethylene-acrylate copolymer used as a constituent of the film according to the present invention is a random copolymer of ethylene and a polar monomer, and has a high content of polar groups and can be prepared by freely adjusting the content, polyethylene, and ethylene-acrylic acid. When used in combination with the copolymer, the compatibility is excellent, so there is no problem of compatibility or selection of a compatibilizer, and excellent meltability, transparency, and oxygen barrier properties. It can be applied to industrial fields.

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

a) ethylene-acrylate copolymer

The first component of the composition according to the invention is an ethylene-acrylate copolymer. The content of the ethylene-acrylate copolymer in the composition according to the invention is preferably 40 to 90% by weight. At this time, if the content is less than 40% by weight, the oxygen barrier property is sharply lowered, so that the effect of the invention is less likely to appear.

In addition, the ethylene-acrylate copolymer is preferably ethylene content of 10 to 50 mol%, acrylate content of 50 to 90 mol%, ethylene content of 15 to 40 mol%, acrylate content of 60 ~ It is more preferable that it is 85 mol%. The ethylene content in the ethylene-acrylate copolymer is an important factor in improving mechanical properties such as flexibility and stretchability, and the acrylate content is an important factor in determining the oxygen barrier property and transparency of the film. Therefore, by appropriately adjusting the content between the monomers in the ethylene-acrylate copolymer, it is possible to have a transparency, mechanical properties and oxygen barrier effect at the same time. When the ethylene content is less than 10 mol%, it is disadvantageous in terms of flexibility and stretchability, and thus it is not suitable for use as a film. When the ethylene content is higher than 50 mol%, it is advantageous for mechanical strength, but the transparency of the film is lowered and Reactivity is significantly lower than acrylate reactivity, making technical implementation difficult from a polymerization standpoint. In particular, if the ethylene content in the range of 15 to 40 mol%, not only technically easy to implement, but also the mechanical strength is further improved.

In addition, the ethylene-acrylate copolymer preferably has a mass average molecular weight of 30,000 g / mol or more, and particularly preferably 70,000 g / mol or more. When the mass average molecular weight of the ethylene-acrylate copolymer is less than 30,000 g / mol, the mechanical strength of the composition and the article made of the composition is lowered, and when it is 70,000 g / mol or more, mechanical strength such as tensile strength is further improved. The higher the mass average molecular weight of the ethylene-acrylate copolymer is, the more preferable, so the upper limit is not particularly limited.

The ethylene-acrylate copolymer in the composition according to the present invention may use a copolymer of ethylene with at least one acrylate comonomer selected from alkyl acrylate and alkyl methacrylate, which is alkyl acrylate or alkyl methacrylate. Particular preference is given to copolymers of at least one comonomer with ethylene. Suitable comonomers which may be copolymerized with ethylene include acrylic and methacrylic esters of straight or branched chain alcohols of 1 to 12 carbon atoms, preferably acrylic or methacrylic chains of straight or branched chain alcohols of 1 to 8 carbon atoms. Acid esters and the like. Examples of alkyl acrylates or alkyl methacrylates suitable for use as comonomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate , t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, and neo-isomer of 2-ethylhexyl (meth) acrylate and an alcohol having 5 to 12 carbon atoms Acrylic acid esters; Particularly preferred comonomers are n-alkyl methacrylates.

Alkyl acrylate or alkyl methacrylate monomers may be used alone or in mixtures. Moreover, you may include ethylene and 3rd monomers other than alkyl acrylate or alkyl methacrylate. Third monomers that may be used include vinyl esters such as vinyl acetate, partial esters of acrylic acid, methacrylic acid or maleic acid, and monomers such as carbon monoxide.

The ethylene content introduced into the ethylene-acrylate copolymer is suitably 10 to 50 mol%, more preferably 15 to 40 mol%. When the ethylene content is less than 10 mol%, it is disadvantageous in terms of flexibility and stretchability, and thus it is not suitable for use as a film. When the ethylene content is 50 mol%, it is advantageous for mechanical strength but the transparency of the film is lowered and the ethylene reactivity is reduced. Since it is significantly lower than the acrylate reactivity, technical implementation is impossible from the viewpoint of polymerization. In particular, when the ethylene content is 15 to 40 mol% or more, not only technically easy to implement, but also the mechanical strength is further improved, and thus more suitable for manufacturing into a film.

b) polyolefins

The second component in the composition according to the invention, the polyolefin, is one from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene, polybutene, polyhexene, polypentene, polyoctene Alternatively, you can select more than one. In addition, the amount of polyolefin used is 5 to 55% by weight, the content is less than 5% by weight, the effect of improving the flexibility is less, and when the content exceeds 55% by weight, the oxygen barrier property tends to decrease rapidly.

c) ethylene- (meth) acrylic acid copolymer

Examples of the ethylene- (meth) acrylic acid copolymer as the third component of the composition according to the present invention include ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers, and one or more thereof may be selected. . This copolymer may be prepared by radical copolymerization of ethylene and (meth) crylic acid, and it is preferably included 1 to 30% by weight based on the whole composition. If the content is less than 1% by weight, the effect of the present invention is hardly exhibited. If the content is more than 30% by weight, the oxygen barrier property is lowered. The ethylene- (meth) acrylic acid copolymer serves to improve the transparency of the molded article produced using the composition and the compatibility between the ethylene acrylate copolymer and the polyolefin.

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

However, the following examples are intended to illustrate the invention, and the invention is not limited thereto.

After the dry blending or melt blending of the composition according to the present invention can be mixed into an extruder to produce a molding, in the case of dry mixing can be carried out using equipment such as a tumbler mixer (Tumbler mixer) In the case of melt mixing, it may be manufactured using equipment such as a brabender mixer, a single-screw extruder, or a twin-screw extruder. In addition, the composition of the present invention can be processed using a processing device, such as blown (Cast), cast (extrusion), etc., the composition of the present invention can be made of a multi-layer film, sheet or container having a single or various structures Can be.

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.

Each component and the content used in each Example and the comparative example are shown in Table 1 below.

ingredient Mark a) ingredients A1 Ethylene-methylmethacrylate copolymer (PEMMA) with 20 mol% ethylene, melt index at 190 ° C. of 5 (g / 10 min, 2.16 kg) A2 Ethylene-methylacrylate copolymer (PEMA) having a melt index of 3.2 mol (g / 10 min, 2.16 kg) at 20 mol% of styrene and 160 ° C b) ingredients B1 Linear low density polyethylene (LLDPE) with a melt index of 0.6 (g / 10 min, 2.16 kg) at 190 ° C c) ingredients C1 Ethylene-acrylic acid copolymer containing 10% by weight of acrylic acid and a melt index of 1.5 (g / 10 min, 2.16 kg) at 190 ° C

Example 1

65 weight percent ethylene-methyl methacrylate having 20 mol% ethylene, 25 weight percent linear low density polyethylene (LLDPE), and 10 weight percent ethylene-acrylic acid copolymer having 10 weight percent acrylic acid content The mixture was dry mixed so that the total amount was 3 kg. The mixture was melt extruded at 140-150-170-190 using a single screw extruder having a diameter of 19 mm to prepare pellets. The prepared pellets were dried at 50 ° C. for 24 hours and then used as a barrier layer to prepare a 20 μm film using a single layer casting film equipment.

[Examples 2 to 7 and Comparative Examples 1 to 9]

Each component and content were made the same as described in Table 2 and Table 3, to prepare a film according to the same method as in Example 1.

[Test Example]

The specimens prepared in Examples and Comparative Examples were fabricated in a horizontal and vertical 10 cm standard, and oxygen permeability was measured by a gas permeability meter (Mocon Oxtran) at a relative humidity of 0%. At this time, the supply oxygen was 99.9% oxygen and the oxygen supply pressure was 0.5 bar and the oxygen permeability was measured at least 1 hour intervals over 12 hours. Tensile strength and elongation were measured using a universal tensile tester (Instron, M 4202) according to ASTM D638. The measured results are shown in Tables 2 and 3 below.

Kinds A1 / B1 / C1 Oxygen Permeability (cc.30㎛ / ㎡.day.atm) The tensile strength Elongation TD MD TD MD Example 1 65/25/10 0.3034 654 634 158 143 Example 2 55/35/10 0.4521 623 601 196 187 Example 3 75/10/15 0.2153 644 623 123 111 Example 4 50/25/25 0.4214 665 645 167 153 Comparative Example 1 35/50/15 5.2443 616 601 234 212 Comparative Example 2 91/6 / 3 0.4324 634 611 76 69 Comparative Example 3 75 / 2/23 0.3524 645 631 45 37 Comparative Example 4 41/57/2 6.2541 639 625 243 211 Comparative Example 5 45/15/40 4.2563 629 605 157 139

Kinds A2 / B1 / C1 Oxygen Permeability (cc.30㎛ / ㎡.day.atm) The tensile strength Elongation TD MD TD MD Example 5 60/20/20 0.5435 589 567 279 259 Example 6 50/30/20 0.4765 547 527 301 287 Example 7 70/15/15 0.3546 598 570 255 244 Comparative Example 6 35/50/15 4.5476 547 533 254 230 Comparative Example 7 91/6/3 0.2999 567 555 77 69 Comparative Example 8 75 / 2/23 0.3145 573 560 39 29 Comparative Example 9 41/57/2 5.4150 599 576 277 256 Comparative Example 10 45/15/40 5.5549 555 535 201 193

In Table 2 and Table 3, it can be confirmed that the oxygen barrier properties, mechanical properties, etc. of the composition according to the present invention is very excellent. In particular, when the content of the components in the composition according to the present invention is out of range, it can be confirmed that the oxygen barrier property or elongation is significantly reduced as the result of the comparative example.

As described above, the oxygen barrier resin composition composed of a) ethylene-acrylate copolymer, b) polyolefin and c) ethylene- (meth) acrylic acid copolymer according to the present invention is excellent in melt formability and compatibility. In addition, there is a feature that the flexibility is superior to the case where the ethylene-acrylate copolymer is used alone as a barrier layer. In addition, it is excellent in appearance (transparency, etc.) and oxygen barrier property, and can be used as a food packaging film and a container, and can be used in various industrial fields.

Claims (11)

(a) 40 to 90% by weight of an ethylene-acrylate copolymer consisting of 10 to 50 mol% of ethylene and 50 to 90 mol% of acrylate; (b) 5-55 weight percent polyolefin; And, (c) 1 to 20% by weight of an ethylene- (meth) acrylic acid copolymer; Oxygen barrier resin composition. The method of claim 1, (a) Ethylene content of the ethylene-acrylate copolymer is 15 to 40 mol%, the acrylate content is characterized in that 60 to 85 mol% Resin composition. The method of claim 1, The mass average molecular weight of the ethylene-acrylate copolymer is characterized in that more than 30,000g / mol Resin composition. The method of claim 3, The mass average molecular weight is characterized in that more than 70,000g / mol Resin composition. The method of claim 1, (a) The ethylene-acrylate copolymer is a copolymer of ethylene and at least one acrylate comonomer selected from alkyl acrylates and alkyl methacrylates. Resin composition. The method of claim 5, The acrylate comonomer is one or more selected from acrylic acid and methacrylic acid esters of linear or branched C1-C12 alcohols. Resin composition. The method of claim 6, The acrylate comonomer is methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl At least one selected from acrylates and acrylic acid esters of neo-isomers of alcohols having 5 to 12 carbon atoms. Resin composition. The method of claim 1, (b) the polyolefin is selected from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene, polybutene, polyhexene, polypentene, polyoctene By Resin composition. The method of claim 1, (c) The ethylene- (meth) acrylic acid copolymer is produced by radical copolymerization, characterized in that Resin composition. An oxygen barrier film comprising the resin composition according to any one of claims 1 to 9. An oxygen barrier container comprising the resin composition according to any one of claims 1 to 9.