JPH0511030B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a multilayer laminate using a modified polyethylene composition with excellent adhesive properties, and this multilayer laminate is suitably used as a packaging film or the like. [Prior Art] Multilayer laminates are known in which two or more types of 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) to which one or more α,β-unsaturated carboxylic acids or their anhydrides are added (modified polyethylenes) and nylon films, etc. It is known that a certain degree of adhesive strength can be obtained when laminated together. [Problems to be solved by the invention] However, films for frozen packaging, etc., which are required to be bonded with strong adhesive strength, and to have excellent transparency, film gloss, gel, mechanical strength, and durability. In this field, multilayer laminates using the above-mentioned modified polyethylene are still insufficient. [Means for Solving the Problems] In view of the above points, the present inventors have developed a multilayer laminate that can be satisfactorily used in the field of frozen packaging films, etc. by laminating it with other resin films. As a result of intensive research in order to provide polyethylene that can be obtained, we have developed two types of modified polyethylene in which specific unsaturated carboxylic acids are grafted onto two specific types of polyethylene, and two types of modified polyethylene in which specific unsaturated carboxylic acids are grafted onto an elastomer or an elastomer. When a modified polyethylene composition blended with a grafted modified elastomer is laminated with another resin film, it has excellent adhesion at low temperatures, durable adhesive strength, and improved transparency, gelling, and mechanical strength. It was discovered that a multilayer structure film can be obtained. The present invention is based on the above findings,
Two types of modified polyethylene (modified high-pressure polyethylene and modified linear low-density polyethylene), each of which is a high-pressure polyethylene and a linear low-density polyethylene grafted with one or more α,β-unsaturated carboxylic acids or its anhydrides, and an elastomer. Alternatively, a modified elastomer in which one or more α,β-unsaturated carboxylic acids or its anhydrides are grafted to 100 parts by weight of modified high-pressure polyethylene,
A layer made of a modified polyethylene composition prepared by blending 5 to 200 parts by weight of modified linear low-density polyethylene and 5 to 200 parts by weight of an elastomer or modified elastomer, and a layer made of a polyolefin and/or a thermoplastic resin having hydrophilic properties. The present invention provides a multilayer laminate consisting of layers. A multilayer laminate using the modified polyethylene composition of the present invention will be described in detail below. Modified high-pressure polyethylene, which is one of the modified polyethylenes used in the present invention, is produced by grafting one or more α,β-unsaturated carboxylic acids or their anhydrides (unsaturated carboxylic acids) to high-pressure polyethylene. be done. As the high-pressure polyethylene mentioned above, in addition to ethylene homopolymers, copolymers with other monomers such as ethylene-vinyl acetate copolymer (EVA) can be used. Preferably, density polyethylene is used. Melt index: 0.05-20g/10min, preferably 0.5-5g/10min, density: 0.915-0.930g/
^cm3 , melting point: 95-115°C. In addition, the unsaturated carboxylic acids mentioned above include α,β- such as maleic acid, itaconic acid, and citraconic acid.
Included are unsaturated carboxylic acids and anhydrides of these acids. The amount of the unsaturated carboxylic acids grafted onto high-pressure polyethylene is 0.01×10 ^-4 to 0.5×
10 ^-4 mole/g (vs. high pressure polyethylene), especially
It is preferable to set the amount to 0.05×10 ⁻⁴ ×0.3×10 ⁻⁴ mole/g. 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 grafted with one or more α,β-unsaturated carboxylic acids or anhydrides thereof (unsaturated carboxylic acids). Manufactured by The linear low density polyethylene is a copolymer of ethylene and α-olefin. This linear low density polyethylene contains ethylene and butene.
It is preferable to use a copolymer with α-olefin selected from the group consisting of 1, hexene-1,4-methylpentene-1, and octene-1, which has the following physical properties. Melt index: 0.5-20g/10min, preferably 2-5g/10min, density: 0.915-0.930g/
^cm3 , melting point: 115-130℃, molecular weight distribution (w/
n): 2-10, preferably 3-6. Further, as the unsaturated carboxylic acids used to obtain the modified linear low-density polyethylene, the same unsaturated carboxylic acids as those exemplified as those used in the production of the modified high-pressure polyethylene can be mentioned. The same method as in the case of producing the above-mentioned modified high-pressure polyethylene can be adopted as the method for grafting onto the modified high-pressure polyethylene. The amount of the above unsaturated carboxylic acids to be grafted onto the linear low density polyethylene is 0.1 to 10 ^-4 to 0.5×
It is preferable to set the amount to 10 ⁻⁴ mole/g (pairwise low density polyethylene). The adhesiveness improves as modified linear density polyethylene having a larger amount of unsaturated carboxylic acids added than modified high-pressure polyethylene is used. 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. Further, examples of the elastomer used in the present invention include ethylene-propylene copolymer rubber, butyl rubber, polyisobutylene, ethylene-butene-1 copolymer rubber, and styrene-butadiene copolymer rubber, with a density of 0.88 to 0.90 g/ cm ³ , melt index 0.1-15g/10 min, especially 0.5-10g/10
Ethylene-propylene copolymer rubber having physical properties of 100% is preferred. Furthermore, the modified elastomer used in the present invention is produced by grafting one or more α,β-unsaturated carboxylic acids or anhydrides thereof (unsaturated carboxylic acids) onto the above-mentioned elastomer. Examples of the unsaturated carboxylic acids used to obtain the above-mentioned modified elastomer include the same ones as those used in the production of the above-mentioned modified high-pressure polyethylene, and methods for grafting these onto the elastomer are also available. The same method as in the case of producing the modified high-pressure polyethylene described above can be employed. The amount of unsaturated carboxylic acids grafted onto the elastomer is preferably 0.5×10 ⁻⁴ mole/g (based on the elastomer) or less. In the modified polyethylene composition used in 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 based on 100 parts by weight of the modified high-pressure polyethylene. 5-200 parts by weight of polyethylene, preferably 10-100 parts by weight, 5-200 parts by weight of elastomer or modified elastomer
200 parts by weight, preferably 10-100 parts by weight. The modified polyethylene composition used in the present invention can be produced by adding unsaturated carboxylic acids to high-pressure polyethylene and linear low-density polyethylene and modifying them separately (this method is most preferred), or by high-pressure This may be carried out by adding unsaturated carboxylic acids to a mixture of processed polyethylene and linear low-density polyethylene to simultaneously modify them, and then blending the elastomer or modified elastomer. Alternatively, high-pressure processed polyethylene, It may be carried out by adding unsaturated carboxylic acids to a mixture of linear low-density polyethylene and an elastomer to simultaneously modify them, or by adding unsaturated carboxylic acids to a mixture of high-pressure polyethylene and an elastomer. This may be carried out by simultaneously modifying these and then separately blending modified linear low-density polyethylene modified with unsaturated carboxylic acids. The multilayer device of the present invention obtained using the above-mentioned modified polyethylene composition is produced by forming the above-mentioned modified polyethylene composition and polyolefin and/or a hydrophilic thermoplastic resin into a film or a thermoplastic resin by a method such as extrusion molding. It is manufactured by forming sheets into sheets and laminating them. In order to obtain a three-layer laminate of the above-mentioned modified polyethylene composition film or sheet and a polyolefin and/or hydrophilic thermoplastic resin film or sheet, the modified polyethylene composition film or sheet is combined with an adhesive layer. As such, it 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 6-nylon, 66-nylon, 11-nylon, 12-nylon, 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 to 210°C, and a number average molecular weight of 20,000 to 40,000.
Nylon with physical properties, especially 6-66 with a low melting point
Copolymerized nylon is preferred because it provides a multilayer laminate with good transparency and less curling. The saponified ethylene-vinyl acetate copolymer (saponified EVA) preferably has physical properties of a melt index of 1 to 6 and a glass transition point of 55 to 75°C. Lamination of the film or sheet of the above-mentioned modified polyethylene composition and the film or sheet of the above-mentioned thermoplastic resin (including polyolefin; the same applies hereinafter) can be achieved by, for example, laminating a film of the modified polyethylene composition and a film of the thermoplastic resin. This can be carried out by a method of heating and pressurizing this, or a method of simultaneously extruding and bonding a film of a modified polyethylene composition and a film of a thermoplastic resin. The following are production examples, examples of the present invention, and comparative examples of modified high-pressure polyethylene, modified linear low-density polyethylene, and modified elastomer, which are the compounding components of the modified polyethylene composition used in the present invention. It will be explained in more detail. Production example 1 Melt index (MI) 2.0g/10 minutes, density
0.922g/ ^cm3 high-pressure polyethylene (manufactured by Ube Industries,
Maleic anhydride 0.3×10 ^-4 mole/g (relative to polyethylene), t-butyl hydroperoxide to high pressure low density polyethylene grade F222N pellets)
After dry blending 0.096×10 ^-4 mole/g (to polyethylene) with a ribbon blender, the resin temperature
Screw diameter 65mm adjusted to 240℃
The high-pressure polyethylene was modified by melt-kneading using an extruder with a diameter of φ and L/D of 22 at a residence time of about 1 minute (modified sample A). Production example 2 Melt index (MI) 2.0g/10 minutes, density
Ethylene-vinyl acetate copolymer (EVA) with a weight of 0.926 g/cm ³ and a VA content of 6% (manufactured by Ube Industries, grade
V206) was denatured in the same manner as in Production Example 1 (modified sample B). Production example 3 High-pressure polyethylene used in production example 1 80% by weight
and melt index (MI) 5.0g/10min, density
A 20% by weight mixture of 0.88 g/cm ³ of ethylene-propylene copolymer rubber (EP rubber) (Mitsui Petrochemicals, Grade Tafmer PO180) was melt-kneaded to form a compound, and this was mixed with 0.3× maleic anhydride.
10 ^-4 mole/g (for the mixture) and t-butyl hydroperoxide 0.096 x 10 ^-4 mole/g (for the mixture) were dry blended using a ribbon blender, Production Example 1
The above mixture was modified by melt-kneading in the same manner as (modified sample C). Production Example 4 A mixture of 80% by weight of EVA used in Production Example 2 and 20% by weight of EP rubber used in Production Example 3 was made into a compound, and then 0.3× maleic anhydride was added to the compound.
10 ^-4 mole/g (for the mixture) and t-butyl hydroperoxide 0.096 x 10 ^-4 mole/g (for the mixture) were dry blended using a ribbon blender, Production Example 1
The above mixture was modified by melt-kneading in the same manner as (modified sample D). Production Example 5 Maleic anhydride was added to the EP rubber used in Production Example 3.
After dry blending 0.5×10 ^-4 mole/g (for EP rubber) and t-butyl hydroperoxide 0.16×10 ^-4 mole/g (for E rubber) using a ribbon blender,
EP rubber was modified by melt-kneading in the same manner as in Production Example 1 (modified sample E). Production example 6 Melt index (MI) 12.0 g/10 min, density 0.926 g/cm ³ , melting point 124°C, molecular weight distribution (w/
Mn) 5.7, maleic anhydride 0.5× in low pressure normal low density polyethylene with a buden-1 concentration of 4 mole%.
10 ^-4 mole/g (relative to polyethylene) and t-butyl hydroperoxide 0.16 x 10 ^-4 mole/g (relative to polyethylene) were dry blended in a ribbon blender, and the resin temperature was adjusted to 240°C. A low-pressure normal low-density polyethylene was modified by melt-kneading using an extruder with a diameter of 65 mm and a L/D of 22 at a residence time of about 1 minute (modified sample F). Production example 7 Melt index (MI) 2.0g/10 minutes, density
0.919g/cm ³ , melting point 123℃, molecular weight distribution (w/
n) 3.3, maleic anhydride 0.3× in low pressure normal low density polyethylene with butene-1 concentration 4 mole%
10 ^-4 mole/g (relative to polyethylene), t-butyl hydroperoxide 0.096 x 10 ^-4 mole/g (relative to polyethylene) was driven in a ribbon blender, and the screw diameter was adjusted so that the resin temperature was 220°C. The low-pressure normal low-density polyethylene was modified by melt-kneading using an extruder of 65 mmφ and L/D22 with a residence time of about 1 minute. (denatured sample G). Production example 8 Melt index (MI) 2.8g/10 minutes, density
0.922g/cm ³ , melting point 116℃, molecular weight distribution (w/
n) 4.5, high-pressure normal low-density polyethylene with 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 mixed with 0.1× itaconic anhydride instead of maleic anhydride.
Modification was carried out in the same manner as in Production Example 1 except that 10 ^-4 mole/g (based on 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). The melt index (MI), density, amount of maleic anhydride added or amount of itaconic anhydride added of the modified samples A to J obtained in Production Examples 1 to 10 are shown in Table 1 below.
are summarized in.

【table】

[Table] Examples 1 to 9 Modified polyethylene compositions were obtained using the formulations shown in Table 3 below. Using these modified polyethylene compositions, two types of two-layer structure films, a modified polyethylene composition film and a nylon film, and a modified polyethylene composition film were produced under the conditions shown in Table 2 below by an air-cooled inflation method. Two kinds of two-layered films with a saponified EVA film were prepared, and their T-peel strength (adhesion) was measured using a tensile tester manufactured by Instron at a speed of 50 mm/min in accordance with JIS K6854. In addition, for these two types of two-layer structure films, the haze and adhesion after hot water treatment at 50℃ for 50 hours and the adhesion after treatment at 80℃ for 50 hours (measured only for the two types of two-layer structure films with nylon film) ) was also measured. The results are shown in Table-3.

【table】

[Table] 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-layered films were prepared using the air-cooled inflation method under the conditions shown in Table 4 below: a nylon film and a polyolefin-in film via a modified polyethylene composition film. Then, peel strength etc. were measured in the same manner as in Examples 1 to 9. The results are shown in Table-5.

[Table] 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 films were prepared using a water-cooled inflation method under the conditions shown in Table 6 below, including a nylon film and a polyolefin-in film via a modified polyethylene composition film. Then, peel strength etc. were measured in the same manner as in Examples 1 to 9. The results are shown in Table-5.

【table】

[Table] Comparative Examples 1 to 8 Modified polyethylene compositions were obtained using the formulations shown in Table 7 below. Using these modified polyethylene compositions, a two-layer structure film consisting of a modified polyethylene composition, a film, and a nylon film, and a modified polyethylene composition were prepared in the same manner as in Examples 1 to 9 by an air-cooled inflation method. Film and saponification
Two kinds of two-layer structure films with EVA film were respectively prepared, and peel strength etc. were measured in the same manner as in Examples 1 to 9. The results are shown in Table-7.

〔Effect of the invention〕

The multilayer laminate of the present invention has excellent adhesion to other resins, and therefore has excellent adhesion at low temperatures and durable adhesive strength. It is suitable for use in frozen packaging films, etc., because it has good properties, has no risk of peeling, and has improved transparency, gelling, and mechanical strength.

Claims (1)

[Claims] 1. Two types of modified polyethylenes, each of which is a high-pressure polyethylene and a linear low-density polyethylene grafted with one or more α,β-unsaturated carboxylic acids or anhydrides thereof, and an elastomer or an elastomer with α,β - A modified elastomer grafted with one or more types of unsaturated carboxylic acids or their anhydrides is added to 100 parts by weight of modified high-pressure polyethylene, 5 to 200 parts by weight of modified linear low density polyethylene, and 5 to 200 parts by weight of the elastomer or modified elastomer. A multilayer laminate comprising a layer made of a modified polyethylene composition blended in a proportion of 1.5 parts, and a layer made of a polyolefin and/or a hydrophilic thermoplastic resin. 2. Claim 1 comprising a layer made of a modified polyethylene composition and two layers made of the same or different polyolefins or hydrophilic thermoplastic resins arranged on both sides of the layer as an adhesive layer. multilayer laminate. 3. The multilayer laminate according to claim 1 or 2, wherein the hydrophilic thermoplastic resin is a saponified product of polyamide or ethylene-vinyl acetate copolymer. 4. The multilayer laminate according to claim 1 or 2, wherein the polyolefin is polyethylene. 5. The multilayer laminate according to claim 3, 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. 6 Saponified ethylene-vinyl acetate copolymer is
The multilayer laminate according to claim 3, having a melt index of 1 to 6 g/10 minutes and a glass transition point of 55 to 75°C. 7 α,β− grafted onto high-pressure polyethylene
The amount of unsaturated carboxylic acid or its anhydride is 0.01×10 ^-4 to 0.5× relative to the high-pressure polyethylene.
10 ^-4 mole/g of the multilayer laminate according to claim 1. 8 High-pressure polyethylene has a density of 0.915 to 0.930
g/cm ² , melt index 0.05-20g/10 minutes,
The multilayer laminate according to claim 1, which is a high-pressure low-density polyethylene having physical properties of a melting point of 95 to 115°C. 9 α grafted onto linear low density polyethylene,
The amount of β-unsaturated carboxylic acid or its anhydride is 0.1×10 ^0.4-0.5 × relative to the linear low density polyethylene.
10 ^-4 mole/g of the multilayer laminate according to claim 1. 10 Linear low density polyethylene contains butene-1,
A copolymer of ethylene and α-olefin selected from the group consisting of hexene-1, 4-methylpentene-1, and octene-1, with a density of 0.915 to 0.930.
g/ ^cm3 , melt index 0.5-20g/10 minutes,
Melting point 115-130℃, molecular weight distribution (w/n) 2-
A multilayer laminate according to claim 1 having physical properties of 10. 11 The elastomer has a density of 0.88 to 0.90 g/cm ³ ,
The multilayer laminate according to claim 1, which is an ethylene-propylene copolymer rubber having physical properties of a melt index of 0.1 to 15 g/10 min. 12. The multilayer laminate according to claim 1, wherein the amount of α,β-unsaturated carboxylic acid or its anhydride grafted onto the elastomer is 0.5×10 ⁻⁴ mole/g or less relative to the elastomer.