JPH0645730B2 - Modified polyethylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a laminate of an ethylene vinyl alcohol copolymer resin, a polyamide resin or a polyester resin, and an ethylene polymer resin, and Specifically, it relates to the improvement of the adhesive resin used for producing the laminate.

[Conventional technology]

Of the so-called polar resin and polyolefin resin, which contains elements such as O, N and Cl in the molecule of ethylene vinyl alcohol copolymer resin or polyamide resin, has a larger surface energy than that of polyolefin and has a larger polarity. The laminate is a composite material that has features such as oil resistance, oxygen permeation resistance, and aroma retention, and water resistance, heat sealability, impact resistance, etc., and is widely used as various packaging materials such as containers and films. It is used. It is also common practice to use a polyolefin resin obtained by modifying the polyolefin resin with an unsaturated carboxylic acid or the like in order to achieve adhesion between the polar resin and the polyolefin resin, which are not bonded by ordinary laminating.

Modified polyethylene resin compositions using a mixture of polyethylenes having different characteristics are described in JP-B-50-33895, JP-A-50-5144, JP-A-52-33941 and the like.

Particularly, in JP-A-52-33941, a mixture of high-pressure polyethylene and medium- and low-pressure polyethylene is used for modification, or by individually modifying with unsaturated carboxylic acid or the like, metal corrosion protection is achieved. A preferred modified polyethylene is described, and Japanese Patent Publication No. 50-33895 describes a metal coating composition using a high-pressure process polyethylene and a medium- and low-pressure process polyethylene graft-modified with a polar monomer. Where is the adhesion with metal.

Further, JP-A-54-82 discloses that a specific ethylene / α-
A composition comprising a modified polyethylene obtained by grafting maleic anhydride onto an olefin copolymer and a crystalline polyolefin resin, and a laminate of nylon, a polyester resin, and an ethylene vinyl alcohol copolymer resin are disclosed. There has been a demand for a composition having improved properties.

[Object of the Invention]

The present inventors have made various studies in such a technical field on a modified polyethylene resin composition that favorably adheres an ethylene vinyl alcohol copolymer resin, a polyamide resin, and a polyester resin to a polymer mainly composed of ethylene. The present invention has found that a composition comprising a high-pressure low-density polyethylene resin having specific flow characteristics and a medium-low pressure method low-density polyethylene resin having specific physical properties has good moldability and excellent adhesiveness. Is completed.

[Structure of Invention]

That is, the gist of the present invention is (A) melt index (MI), and melt tension (MT)
The product (EC) of values of 20 and more, and the melt index (M
I) 0.1 g / 10 min <MI <50 g / 10 min 60 to 95 wt% high-pressure low-density polyethylene, and (B) density 0.880 to 0.910 g / cm ³ ethylene / α
A composition comprising 5 to 40% by weight of modified polyethylene obtained by grafting acrylic acid or maleic anhydride onto an olefin copolymer resin, the melt index (MI) of which is from 0.05 to
50 g / 10 minutes, 0.03 to 1% by weight of graft component in the composition
It exists in the modified polyethylene resin composition containing.

The high-pressure low-density polyethylene resin [component (A)] used in the present invention has a value of the tension {melt tension (MT)} of the molten polymer and a flow index value of the molten polymer {melt index (MI)}. } And the melt index (MI) is 0.1 g / 10 min <MI <50 g / 10
Is a high pressure low density polyethylene. The high-pressure low-density polyethylene resin (A) can be produced by either the tumbler method or the autoclave method,
In the case of manufacturing by the autoclave method, it can be easily manufactured by shifting the reaction conditions to high temperature and high pressure side. The density is preferably about 0.910 to 0.930 g / cm ³ . The crystallinity is preferably about 40 to 60%.
If the EC is less than 20, the desired adhesive strength cannot be obtained, and the upper limit is preferably 40 or less, more preferably 35 or less. If it exceeds 40, molding becomes difficult, and the economic merit is light.

Melt index (MI) is ASTM-D-1238-57T (19
Value (g / 10 minutes) according to the present invention, and in the present invention, high-pressure low-density polyethylene of more than 0.1 g / 10 minutes and less than 50 g / 10 minutes is used, preferably 0.5 g / 1.
Greater than 0 minutes and less than 30 g / 10 minutes are used.

The melt tension was measured at a temperature of 160 ° C., an extrusion rate of 0.25 g / min, and a take-up speed of 152 cm / min by attaching an orifice with a diameter of 2 mmφ, a length of 8 mm and an inflow angle of 180 to a melt tension meter manufactured by Toyo Seiki Co., Ltd. It is a value (g).

The low density polyethylene used in the production of the component (B) is a copolymer of ethylene and α-olefin which is usually polymerized by a Ziegler type catalyst and has a density of 0.880 to 0.910.
It is a linear low density polyethylene of g / cm ³ .

In order to obtain the effects of the present invention, it is desirable that the crystallinity is less than 30%, preferably 2% or more, and 10% or more lower than the crystallinity value of the component (A). .

In order to produce the modified polyethylene as the component (B), a commonly known method using a graft reaction can be used. That is, maleic anhydride or acrylic acid and a radical generator and the low-density polyethylene may be brought into contact with each other under conditions that effectively act as a radical generator. As a reaction condition, a melt-kneading method using an extruder or the like, a polymer in a solvent is used. Any of a solution method in which is dissolved and a slurry method in which polymer particles are suspended may be used.

The amount of acrylic acid or maleic anhydride grafted may be 0.03 to 1% by weight, based on the total composition.
If it is less than 0.03%, the adhesiveness is poor, and if it exceeds 1%, it may be accompanied by problems such as coloring and gel, and the adhesiveness will not be improved.

The compounding amounts of the component (A) and the component (B) are 60 to 95% by weight of the component (A) and 5 to 40% by weight of the component (B). The content of component (B) is 5
If it is less than 40% or more than 40%, the adhesive performance is deteriorated, which is not desirable. Desirably, the amount of component (B) is 15 to 35% by weight.

Additives such as stabilizers, pigments, fillers and the like usually used for polyolefin resins can be added to the composition of the present invention within a range that does not impair the effect. Further, a modifying material such as ethylene / α-olefin copolymer rubber may be added. Further, in some cases, other same or different polyolefin may be added to the composition to form a composition.

The composition obtained as a result of such blending has a melt index of 0.05 to 50 g / 10 min, preferably 0.5 to 30 g / min.
It is desirable to have a melting property of about 10 minutes, for this reason
It is necessary to appropriately select the components (A) and (B).

The composition of the present invention is laminated with a polar resin such as an ethylene vinyl alcohol copolymer resin or a polyamide resin or a polyethylene resin, or as an intermediate layer between the polar resin and an ethylene-based polymer resin, it is melt-laminated by multilayer coextrusion molding or the like. It can then be used to make a laminate.
The ethylene-based polymer resin as referred to herein is a homopolymer or copolymer containing ethylene monomer as a main component, and the comonomer component is α-olefin having about 3 to 12 carbon atoms, vinyl acetate, non-conjugated diene, butadiene or the like. Any diene, acrylic acid, methacrylic acid and their derivatives, and other ethylene-polymerizable comonomers may be used. Further, the mode of copolymerization is not limited to the random copolymer, and includes copolymerization in the form of graft or block.

The ethylene-vinyl alcohol copolymer is an ethylene-vinyl acetate copolymer obtained by partially or almost saponifying an acetic acid group to form an OH group, and the chemical composition thereof is not limited, and for example, an average molecular weight of 10,000 to A polymer having an ethylene content of 100,000 and an ethylene content of 10 mol% to 70 mol% is used, and an ethylene-vinyl acetate copolymer having an ethylene content of 50 to 30 mol% is used in consideration of gas barrier properties, film moldability and the like. Those obtained by saponification so that the saponification degree is 90% or more are preferable.

The polyamide resin is a linear polymer having an acid amide bond obtained by ring opening of a lactam, condensation of a diamine and a dicarboxylic acid, or the like, for example, an average molecular weight of 15,000 to 60,000.
[Η] = 1.0 to 6.0 dl / g is used, and specifically, nylon 6, nylon 6.6, nylon 6.10, nylon 11, nylon 6.11, nylon 6T, etc. are used. it can. The polyester resin is obtained by condensation of saturated dibasic acid and glycols, and has, for example, an average molecular weight of 15,000 to 45,000 and [η] = 1.0 to
About 6.0 dl / g is used, and specifically, a saturated dibasic acid such as polyethylene terephthalate obtained from ethylene glycol and terephthalic acid, adipic acid, azelaic acid, succinic acid, oxalic acid, phthalic acid, and isophthalic acid. Polyethylene terephthalate copolymers containing as a copolymer component can be used. Further, a copolymer such as a polyester amide in which an amide bond structure is partially introduced into the above polyester structure polymer can also be used in the present invention.

〔Example〕

One example of the method of the present invention will be described below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Production Example and Adhesive Strength Measurement Method [High Pressure Method Low Density Polyethylene Production Example] [Polyethylene
(A)] Using an autoclave type high pressure reactor, ethylene was polymerized using a radical initiator to obtain the following two types of polyethylene.

[Medium- and low-pressure method low-density polyethylene production example] [Polyethylene
(B)] <Polyethylene;b-1> Copolymerization of ethylene and butene-1 in ethylene dichloride using a catalyst composed of vanadium oxytrichloride and ethylaluminum sesquichloride according to the method of JP-B-55-30524. I went.

<Polyethylene;b-2> Magnesium chloride, titanium trichloride, and a catalyst component using tetrahydrofuran as an electron donor and triethylaluminum according to the method of JP-A-59-68306, and ethylene and butene using butane as a solvent. -1 was copolymerized.

<Polyethylene;b-3> Ethylene and butene-1 at 70 ° C using a titanium catalyst supported on a magnesium compound.
The copolymerization of

The polymer properties of each are as follows.

[Modified Polyethylene Production Example] b-1, b-2, b-3, 0.5 parts by weight of maleic anhydride to 100 parts by weight of each, and 0.025 parts by weight of α, α'-di-t-butylper. The copolymer was modified by mixing oxyparaisopropylbenzene, melt-kneading at 210 ° C. using a single screw extruder having an inner diameter of 30 mmφ and L / D = 24, and grafting.

The graft ratio was determined by infrared spectroscopy after removing unreacted monomers by extraction with acetone. The results are shown in Table-1.

[Modified polyethylene resin composition production example]

High-pressure low density polyethylene a-1, a-2 and modified polyethylene b-1, b-2, b-3 were mixed as shown in Table 1 to produce various modified polyethylene resin compositions. The mixing was performed by melt kneading at 210 ° C. using a single screw extruder having an inner diameter of 40 mmφ and L / D = 24. The results are shown in Table-1.

[Adhesive strength measurement method]

Modified polyethylene composition and ethylene-vinyl alcohol copolymer resin (ethylene content 39 mol%, saponification degree about 100%, melt index at 210 ° C. 8 g / 10
() Was coextruded in a die to prepare a composite inflation film having an adhesive polyethylene composition as an inner layer and an ethylene-vinyl alcohol resin as an outer layer. Co-extrusion was performed at a die inner diameter of 75 mmφ, a die temperature of 205 ° C., a polyolefin composition side extruder L / D = 26, a temperature of 205 ° C., an ethylene vinyl alcohol resin side extruder L / D = 26, and a temperature of 205 ° C. The winding speed is 6.2 m / min, the blow-up ratio is 2, the ethylene vinyl alcohol resin thickness is 25 μ, and the modified polyethylene thickness is 25 μ.

The T peel strength of this composite film complies with JIS K6854,
It was measured. The results are shown in Table-1.

Examples 1 to 5 high-pressure method low-density polyethylene a-1 and modified polyethylene b
A composite film of a modified polyethylene resin composition obtained by mixing -1, b-2 with each other and an ethylene / vinyl acetate copolymer saponified resin (EV-OH resin) was molded, and the adhesive strength was measured. . The results are shown in Table-1.

Comparative Examples 1 to 4 Adhesive strength was measured in the same manner as in Examples using a-2 as the high-pressure low-density polyethylene and b-1, b-2, and b-3 as modified polyethylene. The results are shown in Table-1.

[Effects of the Invention] The resin composition of the present invention is industrially useful because it has good moldability and excellent adhesiveness with polar resins.

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Claims (1)

[Claims] 1. A product (EC) of (A) melt index (MI) value and melt tension (MT) value is 20 or more, and melt index (MI) is 0.1 g / 10 min. <MI <50g
High-pressure low density polyethylene 60 to 95% by weight, which is / 10 minutes, and (B) ethylene 0.8 with a density of 0.880 to 0.910 g / cm ^3.
A composition comprising 5 to 40% by weight of a modified polyethylene obtained by grafting acrylic acid or maleic anhydride onto an olefin copolymer, wherein a melt index (MI) of 0.
05-50 g / 10 min, the graft component in the composition was adjusted to 0.
Modified polyethylene resin composition containing 03 to 1% by weight