JPS6119647A - Modified polyethylene composition and multilayer laminate prepared by using it - Google Patents

Abstract

PURPOSE:A modified polyethylene composition having excellent adhesiveness, made by mixing two kinds of modified polyethylenes and a (modified) elastomer. CONSTITUTION:A modified polyethylene composition which comprises 100pts.wt. modified polyethylene (A) obtained by grafting a high-pressure polyethylene (having a density of about 0.915-0.93g/cm<3>, an MI of about 0.05-20g/10min, and a melting point of about 95-115 deg.C) with (0.01-0.5)X10<-4>mol of an alpha,beta-unsaturated carboxylic acid (anhydride) per 1g of the polyethylene, about 5-200pts.wt. modified polyethylene (B) obtained by graft-modifying an linear low-density polyethylene (having a density of about 0.915-0.93g/cm<3>, a MI of about 0.5-20g/10min, a melting point of about 115-130 deg.C, and a molecular weight distribution of about 2-10) similarly, and about 5-200pts.wt. elastomer (e.g. an ethylene-propylene copolymer rubber having a density of about 0.88-0.9g/cm<3> and an MI of about 0.1-15g/10min) or product obtained by graft-modifying it similarly.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a modified polyethylene composition with excellent adhesive properties and a multilayer laminate using the same. molded into
It is used alone or laminated with a polyolefin or hydrophilic thermoplastic resin film or sheet as a packaging film, etc. It is also used as an adhesive in the form of a powder, film, or sheet.

[Conventional technology]

Multilayer laminates are known in which two or more resin films or sheets are laminated to take advantage of the advantages of each resin.

In addition, polyethylenes such as low-density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) with one or more α,β-unsaturated carboxylic acids or their anhydrides added (modified polyethylene) and nylon It is known that a certain degree of adhesive strength can be obtained by laminating films and the like.

[Problem that the invention seeks to solve]

However, the modified polyethylene mentioned above is used in fields such as frozen packaging films, which require strong adhesive strength and excellent transparency, film gloss, shell, mechanical strength, and durability. The existing multilayer laminates were still insufficient.

[Means for solving problems]

In view of the above-mentioned points, the present inventors have provided a polyethylene that can be laminated with other resin films to obtain a multilayer laminate that can be satisfactorily used in the field of frozen packaging films and the like. As a result of careful consideration,
A modified polyethylene composition is a blend of two types of modified polyethylene in which specific unsaturated carboxylic acids are grafted onto two specific types of polyethylene, and an elastomer or a modified elastomer in which specific unsaturated carboxylic acids are grafted onto an elastomer. It has been found that when laminated with a resin film, a multilayer structure film with excellent adhesion at low temperatures, durable adhesive strength, and improved transparency, shell, and mechanical strength can be obtained.

The present invention was made based on the above findings, and the present invention has been made based on the above findings.
Two types of modified polyethylenes (modified high-pressure polyethylene and modified linear low-density polyethylene) grafted with one or more β-unsaturated carboxylic acids or their anhydrides, and elastomers or elastomers with α,β-unsaturated carboxylic acids or their anhydrides. A modified polyethylene composition comprising a modified elastomer grafted with one or more types of compounds, and a multilayer laminate comprising a layer made of this modified polyethylene composition and a layer made of a polyolefin and/or a thermoplastic resin having hydrophilic properties. It provides:

The modified polyethylene composition of the present invention and the multilayer laminate using the same will be explained in detail below.

Modified high-pressure polyethylene, which is one of the modified polyethylenes used in the present invention, is α-, β-
It is produced by grafting one or more unsaturated carboxylic acids or their anhydrides (unsaturated carboxylic acids).

As the high-pressure polyethylene, in addition to ethylene homopolymers, copolymers with other monomers such as ethylene-vinyl acetate copolymer (EVA) can be used. In particular, high-pressure polyethylene having the following physical properties can be used. Preferably, density polyethylene is used.

Melt index: [), 05-20 g/10 min, preferably 0.5-5 g/10 min, density: 0.9
15-0.930g/c+a.

Melting point: 95-115°C.

In addition, the unsaturated carboxylic acids mentioned above include maleic acid,
Examples include α, β-unsaturated carboxylic acids such as itaconic acid and citraconic acid, and anhydrides of these acids.

The amount of the unsaturated carboxylic acids grafted onto the high-pressure polyethylene is 0.01 x 10 to 0.5 x 10
--4 mole/g ((vs. high pressure polyethylene), especially 0.05 x 10 ~ 0.3 x 10-4 mole/g
It is preferable to set it so that -+.

As a method for grafting the above-mentioned unsaturated carboxylic acids onto high-pressure polyethylene, for example, a mixture of high-pressure polyethylene and unsaturated carboxylic acids is used in an extruder or the like in the presence of a polymerization initiator such as t-butyl hydroperoxide. Examples include a method of melt-kneading.

In addition, modified linear low density polyethylene, which is another modified polyethylene used in the present invention, is a linear low density polyethylene containing α,β-unsaturated carboxylic acid or its anhydride (
It is produced by grafting one or more types of unsaturated carboxylic acids).

The linear low density polyethylene is a copolymer of ethylene and α-olefin. This linear low density polyethylene includes ethylene, butene-1, hexene-1,4
- It is preferable to use a copolymer with an α-olefin selected from the group consisting of methylpentene-1 and octene-1, which has the following physical properties.

Melt index: 20.5-20 t/10 min, preferably 2-15 g/10 min, density: 0.915-0.
930g/cd, melting point: 115-130℃, molecular weight distribution (L/Pro): 2-10゜', preferably 3
~6° Furthermore, as the unsaturated carboxylic acids used to obtain the modified linear low-density polyethylene, there may be mentioned those similar to those exemplified as those used in the production of the modified high-pressure polyethylene, and As for the method of grafting these onto linear low density polyethylene, the same method as in the case of producing the modified high-pressure polyethylene described above can be adopted.

The amount of the unsaturated carboxylic acids grafted onto the linear low density polyethylene is 0. I ×10-4～0.5×10
-4mole/g (pair-linear low density polyethylene)
It is preferable to do so. The adhesiveness improves as modified linear low-density polyethylene containing a larger amount of unsaturated carboxylic acids is used than modified high-pressure polyethylene.

In particular, the best adhesion is achieved when modified linear low-density polyethylene grafted with about three times the amount of unsaturated carboxylic acids added to the modified high-pressure polyethylene is used.

In addition, the elastomers used in the present invention include ethylene-propylene copolymer rubber, butyl rubber, polyisobutylene, ethylene-butene-1 copolymer rubber, and styrene-1 copolymer rubber.
Examples include butadiene copolymer rubber, especially with a density of 0.88
~0.90 g/cJ, melt index 0.1-1
Ethylene-propylene copolymer rubber having physical properties of 5 g/10 min, particularly 0.5 to 10 g/10 min, is preferable.

Furthermore, the modified elastomer used in the present invention is produced by grafting one or more α, β to unsaturated carboxylic acids or their anhydrides (unsaturated carboxylic acids) onto the above elastomer.

Examples of the unsaturated carboxylic acids used to obtain the above-mentioned modified elastomer include those similar to those exemplified as those used in the production of the above-mentioned modified high-pressure polyethylene, and there are also methods for grafting these onto the elastomer. The same method as in the case of producing the modified high-pressure polyethylene described above can be employed.

It is preferable that the amount of unsaturated carboxylic acids grafted onto the nilastor is 0.5 XIO, mole/g (based on the elastomer) or less.

In the modified polyethylene composition of the present invention, the blending ratio of the modified high-pressure polyethylene, the modified linear low-density polyethylene, and the elastomer or modified elastomer is as follows:
5 to 200 parts by weight, especially 10 to 1 part by weight of modified linear low density polyethylene per 100 parts by weight of modified high pressure polyethylene
00 parts by weight, elastomer or modified elastomer 5~
It is preferably 200 parts by weight, particularly 10 to 100 parts by weight.

The production of the modified polyethylene composition of the present invention involves adding unsaturated carboxylic acids to high-pressure polyethylene and linear low-density polyethylene and modifying them separately (
(This method is most preferred), or by adding unsaturated carboxylic acid to a mixture of high-pressure polyethylene and linear low-density polyethylene to simultaneously modify them, and then blending the elastomer or modified elastomer. Alternatively, it may be carried out by adding unsaturation force or rubonic acid granules to a mixture of high-pressure polyethylene, linear low-density polyethylene, and elastomer to simultaneously modify them. This may be carried out by adding unsaturated carboxylic acids to a mixture of the above and modifying them simultaneously, and then separately blending modified linear low-density polyethylene modified with unsaturated carboxylic acids.

The above-mentioned modified polyethylene 4 composition of the present invention can be molded into a film or sheet by a method similar to that used for ordinary polyethylene, such as extrusion molding, and can be used alone or with a polyolefin and/or a hydrophilic thermoplastic resin. It is laminated with other films or sheets and used as a packaging film, etc. It is also used as an adhesive in the form of powder, film, or sheet.

The multilayer laminate obtained using the modified polyethylene composition of the present invention can be produced by forming a film or a polyolefin by extruding the modified polyethylene composition of the present invention and a polyolefin and/or a thermoplastic resin having hydrophilic properties, respectively. It is manufactured by forming sheets into sheets and stacking them. In order to obtain a three-layer laminate of a film or sheet of the modified polyethylene composition of the present invention and a film or sheet of polyolefin and/or a thermoplastic resin having hydrophilic properties, an adhesive is used for the film or sheet of the modified polyethylene composition. The layer may be interposed between two films or sheets of polyolefin and/or hydrophilic thermoplastic resin.

Preferred examples of the hydrophilic thermoplastic resin include polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, and 6-66 copolymerized nylon, and saponified ethylene-vinyl acetate copolymers (partially saponified products). ).

Moreover, polyethylene is mentioned as the said polyolefin.

The above polyamide has a melting point of 195 to 225°C.

Preferably 200-210°C, number average molecular weight 20,00
Nylon having physical properties of 0 to 40,000, particularly 6-66 copolymer nylon having a low melting point, is preferred because it provides a multi-N laminate with good transparency and less curling.

The saponified ethylene-vinyl acetate copolymer (saponified EVA) has a melt index of 1 to 6. Those having physical properties with a glass transition point of 55 to 75°C are preferred.

Lamination of a film or sheet of the modified polyethylene composition of the present invention and a film or sheet of the above-mentioned thermoplastic resin (including polyolefin; hereinafter referred to as "intermediate") can be performed, for example, by laminating a film or sheet of the modified polyethylene composition and a film of the thermoplastic resin. This can be carried out by a method of superimposing them and heating and pressing them, or by a method of simultaneously extruding a modified polyethylene composition film and a thermoplastic resin film and joining them.

The following are production examples of modified high-pressure polyethylene, modified linear low-density polyethylene, and modified elastomer, which are ingredients of the modified polyethylene composition of the present invention, Examples of the present invention,
The present invention will be explained in more detail by showing and comparative examples.

Melt index (MI) 2. (l g/1
Maleic anhydride 0.3
10 mole/g (relative to polyethylene), t-butyl hydroperoxide 0.096 XIOmole/g
After tri-blending (versus polyethylene) with a ribbon blender, the resin temperature was adjusted to 240°C.
The high-pressure polyethylene was modified by melt-kneading using an extruder with a screw i-thread of 65 mmφ and L/D 22 for a residence time of about 1 minute (modified sample A).

Production example 2 Melt index (MT) 2.0 g/10
min, density 0.926 g/cJ, VA content 6% by weight
Ethylene-vinyl acetate copolymer (EVA) (Ube Industries, Grade V 206) was modified in the same manner as in Production Example 1 (modified sample B).

Production Example 3 Ethylene-propylene copolymer rubber (BP rubber) with 80% by weight of the high-pressure polyethylene used in Production Example 1 and a melt index (MI) of 5.0 g/10 min. After melting and kneading a 20% by weight mixture (manufactured by Kagaku, Grade Tafmer P0180) to form a compound, 0.3% of maleic anhydride was added to the compound.
XIOmole/g (pair mixture), t-butyl hydroperoxide 0.096 X 10 mole/
g (pair mixture) was tri-blended using a ribbon blender, and then melt-kneaded in the same manner as in Production Example 1 to modify the mixture (modified sample C).

Production Example 4 A mixture of 80% by weight of the EVA used in Production Example 2 and 20% by weight of the EP rubber used in Production Example 3 was made into a compound, and then maleic anhydride 0.3XIO14mole/
g (versus mixture), t-butyl hydroperoxide 0
．． 096 x 10 mole/g (pair mixture) was tri-blended using a ribbon blender, and then melt-kneaded in the same manner as in Production Example 1 to modify the mixture (modified sample D).

Production Example 5 0.5 maleic anhydride was added to the EP rubber used in Production Example 3.
×10--4mole/g (vs. BP rubber), t-
Butyl hydroperoxide 0.16X10-4mole
/g (vs. EP rubber) using a ribbon blender, and then melt-kneaded in the same manner as in Production Example 1 to modify the EP rubber (modified sample E).

Production example 6 Melt index (MI) 12.0g/10
min, density 0.926g/cJ, melting point 124℃ 1 molecular weight distribution (Ww/Kn) 5.7. Butene-1 concentration 4m
ole% of low pressure normal low density polyethylene, maleic anhydride 0.5%, mole/g (relative to polyethylene), t-butyl hydroperoxide 0.16X10-
-4 mole/g (versus polyethylene) was tri-blended using a ribbon blender, and the resin temperature was adjusted to 240°C. Screw diameter: 65 mmφ, L/D: 22
The low-pressure normal low-density polyethylene was modified by melt-kneading using an extruder with a residence time of about 1 minute (modified sample F).

Production Example 7 Melt index (MI) 2.0 g/10 min, density 0.919 g/ct, melting point 123°C 1 molecular weight distribution (Nw/πn) 3.3. Butene - 1g degree 4mo
le% low pressure normal low density polyethylene, maleic anhydride 0.3 x 10-4 mole/g (relative to polyethylene), t-butyl hydroperoxide 0.096 x
After tri-blending IOmole/g (versus polyethylene) with a ribbon blender, the resin temperature was adjusted to 220°C, screw diameter 65mmφ, L/D 22
The low-pressure normal low-density polyethylene was modified by melt-kneading using an extruder with a residence time of about 1 minute (modified sample G).

Production example 8 Melt index (MI) 2.8g/10
High-pressure normal low-density polyethylene with a density of 0.922 g/cl, a melting point of 116°C, a molecular weight distribution (L/Mn) of 45, and a butene-1 concentration of 4 mole% was modified in the same manner as in Production Example 7 (modified sample H). .

Production Example 9 The high-pressure polyethylene used in Production Example 1 was treated with 0.0% itaconic anhydride instead of maleic anhydride. I ×10−4mo
Modification was carried out in the same manner as in Production Example 1 except that le/g (relative to polyethylene) was used (modified sample I).

Production Example 10 The low pressure normal low density polyethylene used in Production Example 7 was modified in the same manner as Production Example 7 except that itaconic anhydride was used instead of maleic anhydride (Modified Sample J).

Modified samples A-J obtained in Production Examples 1 to 10
,.

The melt index (Ml), density, amount of maleic anhydride added or amount of itaconic anhydride added are summarized in Table 1 below.

Table-1 Note] *1 and *2: Measured by piercing JIS 6760.

*3: Measured by infrared absorption spectrum of a sheet compression molded to a thickness of 0.3±0.05 nvn.

- Modified samples A-H used maleic anhydride, and modified samples I and J used itaconic anhydride as unsaturated carboxylic acids.

Examples 1 to 9 Modified polyethylene compositions were obtained using the formulations shown in Table 3 below.

Using these modified polyethylene compositions, saponification was carried out by an air-cooled inflation method under the conditions shown in Table 2 below to form a two-layer structure film of a modified polyethylene composition film and a nylon film, and a modified polyethylene composition film. Two types of two-layered films with EVA film were prepared and tested at a speed of 50 mm/min using an Instron tensile tester in accordance with JIS K6854.
Mold peel strength (adhesion) was measured. In addition, regarding these two types of 2N structure films, the haze and 50°C
The adhesion properties after 0-hour hot water treatment and after 50-hour treatment at 80°C (measured only for the two-layer two-layer structure film with the nylon film) were also measured. Table the results.
Shown in 3.

Examples 10 and 11 Modified polyethylene compositions were obtained using the formulations shown in Table 5 below.

Using these modified polyethylene compositions, three types of three-layer structure films were created using a nylon film and a polyolefin film via a modified polyethylene composition film under the conditions shown in Table 4 below by an air-cooled inflation method, Peel strength etc. were measured in the same manner as in Examples 1 to 9. The results are shown in Table-5.

Examples 12 and 13 Modified polyethylene compositions were obtained using the formulations shown in Table 5 below.

Using these modified polyethylene compositions, three types of three-layer structure films were respectively created using a nylon film and a polyolefin film via a modified polyethylene composition film under the conditions shown in Table 6 below using a water-cooled inflation method. Peel strength etc. were measured in the same manner as in Examples 1 to 9. The results are shown in Table-5.

Comparative Examples 1 to 8 Modified polyethylene compositions were obtained using the formulations shown in Table 7 below.

Using these modified polyethylene compositions, a modified polyethylene composition film and a nylon film were formed in the same manner as in Examples 1 to 9 by the air-cooled inflation method.
A seed two-layer structure film and a two-type two-layer structure film of a modified polyethylene composition film and a saponified EVA film were respectively created, and peel strength etc. were measured in the same manner as in Examples 1 to 9. The results are shown in Table-7.

[Effects of the present invention]

The modified polyethylene composition of the present invention has excellent adhesion with other resins, so by forming it into a film or sheet and laminating it with other resin films or sheets, it has excellent adhesion at low temperatures and It has durable adhesive strength, has no risk of peeling, and has improved transparency, shell and mechanical strength, and can be used to obtain multilayer laminates that are particularly suitable for use in frozen packaging films, etc. In addition, it can be used as an adhesive in the form of powder, film, or sheet.Furthermore, the film, sheet, etc. formed from the modified polyethylene composition of the present invention has various advantages such as good printability and dyeability. It has a certain effect.

Claims (14)

[Claims] (1) Two types of modified polyethylenes, high-pressure polyethylene and linear low-density polyethylene grafted with one or more α,β-unsaturated carboxylic acids or their anhydrides, and an elastomer or an α,β-unsaturated carboxylic acid added to the elastomer. A modified polyethylene composition comprising a modified elastomer grafted with one or more acids or anhydrides thereof. (2) The amount of α,β-unsaturated carboxylic acid or its anhydride grafted onto high-pressure polyethylene is 0.01×10^-4 to 0.5×10^- with respect to the high-pressure polyethylene.
The modified polyethylene composition according to claim (1), which has a molecular weight of ^4 mole/g. (3) High-pressure polyethylene has a density of 0.915 to 0.9
30g/cm^3, melt index 0.05-20
The modified polyethylene composition according to claim 1, which is a high-pressure low-density polyethylene having physical properties of g/10 minutes and a melting point of 95 to 115°C. (4) α, β-grafted onto linear low-density polyethylene
The amount of unsaturated carboxylic acid or its anhydride is 0.1 x 10^-^4 to 0.5 x 1 to the linear low density polyethylene.
Claim No. (1) which is 0^-^4 mole/g
The modified polyethylene composition described in Section 1. (5) The linear low density polyethylene is a copolymer of ethylene and an α-olefin selected from the group consisting of butene-1, hexene-1, 4-methylpentene-1, and octene-1, and has a density of 0. 915-0.930g/cm^3, melt index 0.5-20g/10min, melting point 115
~130°C, molecular weight distribution (@M@w/@M@n) 2-1
The modified polyethylene composition according to claim (1), which has physical properties of 0. (6) The elastomer has a density of 0.88 to 0.90 g/c
The modified polyethylene composition according to claim 1, which is an ethylene-propylene copolymer rubber having physical properties of m^3 and a melt index of 0.1 to 15 g/10 min. (7) The amount of α,β-unsaturated carboxylic acid or its anhydride grafted to the elastomer is 0% relative to the elastomer.
．． The modified polyethylene composition according to claim (5), which has a molecular weight of 5×10^-^4 mole/g or less. (8) The blending ratio of modified high-pressure polyethylene, modified linear low-density polyethylene and elastomer or modified elastomer is 5 to 200 parts by weight of modified linear low-density polyethylene, elastomer or modified elastomer to 100 parts by weight of modified high-pressure polyethylene. The modified polyethylene composition according to claim (1), which contains 5 to 200 parts by weight of elastomer. (9) Two types of modified polyethylenes, in which one or more types of α,β-unsaturated carboxylic acids or their anhydrides are grafted to high-pressure polyethylene and linear low-density polyethylene, and elastomer or α,β-unsaturated carboxylic acid to the elastomer. A multilayer laminate comprising a layer made of a modified polyethylene composition blended with a modified elastomer grafted with one or more acids or anhydrides thereof, and a layer made of a polyolefin and/or a thermoplastic resin having hydrophilic properties. (10) Claim No. 1 consisting of a layer made of a modified polyethylene composition and two layers made of the same or different polyolefins or thermoplastic resins having hydrophilic properties disposed on both sides of the layer as an adhesive layer. 9) The multilayer laminate described in item 9). (11) The multilayer laminate according to claim (9) or (10), wherein the hydrophilic thermoplastic resin is a saponified product of polyamide or ethylene-vinyl acetate copolymer. (12) The multilayer laminate according to claim (9) or (10), wherein the polyolefin is polyethylene. (13) The multilayer laminate according to claim (11), wherein the polyamide is nylon having physical properties of a melting point of 195 to 225°C and a number average molecular weight of 20,000 to 40,000. (14) Saponified ethylene-vinyl acetate copolymer has a melt index of 1 to 6 g/10 minutes and a glass transition point of 55.
The modified polyethylene composition according to claim (11), which has physical properties at a temperature of -75°C.