JPS59120454A - Laminate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminate, in particular a layer made of low density polyethylene with a specific melt flow ratio (MF
Laminated layers of high density polyethylene with R). The present invention relates to a laminate having excellent physical properties such as moisture resistance and mechanical strength, and suitable for packaging bags, containers, etc.

Conventionally, bags and containers made of high-density polyethylene and low-density polyethylene have been used in packaging fields that require moisture resistance, such as copy paper packaging bags, food packaging bags, and packaging containers.

However, low-density polyethylene does not have sufficient mechanical strength or moisture resistance, and in order to meet these requirements, a thick film or sheet must be used to meet the requirements for resource conservation. The disadvantage is that it cannot be used. For this reason, attempts have been made to use high-density polyethylene, which has excellent strength, to make the wall thinner, but ordinary high-density polyethylene for films with high impact resistance has a moisture resistance rating of
Special high-density polyethylene with excellent moisture resistance can withstand more than 1 minute! Both Y strength and tear strength were low, and it was not possible to meet the demand for thinner films.

Moreover, the moldability of the film was poor, and it was difficult to obtain high-quality film products with good productivity.

The present invention eliminates the drawbacks of the prior art as described above, and has a moisture-proof property of 1.
The object of the present invention is to provide a laminate having excellent mechanical strength, good moldability, high productivity, and suitable for packaging bags, containers, etc.

That is, the present invention provides various layers of low density polyethylene (
A) through 7 and on both sides melt flow ratio (MFR) 10
The present invention provides a laminate formed by laminating layers (B) of 60 to 60 high-density polyethylenes.

Here, low-density polyethylene is used as the layer (A), and its properties are not particularly limited, but it usually has a melt index (MI) of 0.1 to 1 Og/10 minutes, preferably 0.
．． 2~5+1? /10 minutes, density 0.91.0-0940
g/cm" is used.

The low-density polyethylene constituting the layer (A) includes homopolymers of ethylene, copolymers of ethylene and other α-olefins, and evaporated ethylene-7.
0 robylene co-m copolymer, edylene-zotene=l copolymer,
Examples include ethylene-4-methylbenzone-1 copolymer, which includes linear low-density polyethylene (LLDPE). Further examples include ethylene-unsaturated ester copolymers such as ethylene-vinyl acetate copolymers and ethylene-acrylic acid ester copolymers, and mixtures thereof. Note that the content of the component copolymerized with ethylene, i.e., α j-17 fin and unsaturated ester, in the copolymer is 1 to 30 mol%, preferably 1
The range is 15% to 15%.

This layer (A) made of low-density polyethylene has excellent mechanical strength such as impact strength and tear strength. Also, this low-density polyethylene has excellent moldability,
Either it cannot be stably molded, or it has poor moisture resistance. Therefore, in the present invention, the (B) layer is laminated on both sides of the (8) layer (~) to improve moisture resistance, etc.

As this layer (I3), high-density polyethylene having an MFR of 10 to 60, preferably 15 to 50 is used. Note that this MFR is defined as the ratio of the met index (MI2, +61y) of 7 to the load 2L6, that is, M I2.+6ky, and serves as an index of molecular weight distribution.

The high-density polyethylene constituting the layer (I3) above is "-
It has an MFR of 5,000 g/cm3, and its density is usually in the range of 0.945 to 0.970 g/cm3. As, 0.1 to 2 0, !i'/10 minutes,
Preferably it is 0.2 to 5 v]O minutes. Such high-density polyethylene includes not only ethylene homopolymers, but also copolymers of ethylene and other α-olefins (α-olefin unit content of 10 mol% or less), such as ethylene loop O pyrene. Copolymers, ethylene-butene-1 copolymers, etc. can be used. If necessary, an appropriate amount of another tree, rubber, etc. can be added to this (B) layer.

This (I3) layer made of high-density polyethylene has somewhat poor moldability and extremely low mechanical strength, particularly tear strength in one direction, but has excellent moisture resistance. Therefore, in the present invention, the layer (B) is laminated on both sides of the layer (A), which has excellent mechanical strength such as impact strength and tear strength, but is inferior in moisture resistance, to achieve moisture resistance. As a result, a laminate with excellent mechanical strength can be obtained.

In addition, in the present invention, the layer (I3) laminated on both sides of the layer (A) does not need to be exactly the same as long as it is made of high-density polyethylene with an MFR l O~6033. The body is basically written as (A
) layer and (B) layer on both sides, or if necessary, an additional layer of low density polyethylene may be provided on the outer layer of (B) layer. enemy,
It is possible to aim for two things in the direction of transparency.

In addition, in the present invention, if desired, face *-1 and dye.

Stabilizers, slip agents, etc. may be added.

Various methods can be applied to produce the laminate of the present invention using low density polyethylene and high density polyethylene, which are the materials for the above (A) layer and (B) layer. Coextrusion inflation molding/
The carcass can be obtained in film form by molding or coextrusion T-die molding.

The ratio of the thicknesses of the (A) layer and the (f3) layer in this laminate is not particularly limited, but usually for (A) layers 2 to 5,
(13) It should be 8 to 5 layers (which is the thickness of two layers).

As described above, the laminate of the present invention is composed of two or three polyethylene layers that are different from each other in terms of materials and materials and complement each other's shortcomings. 4. This laminate has good moldability, high productivity, and is of high quality. Since I-7 also has sufficient mechanical strength, it can be made thinner and resource saving can be achieved.

Therefore, the laminate of the present invention can be effectively used as various packaging bags and containers, especially as moisture-proof packaging bags or containers for copy paper and dry foods that are sensitive to moisture.

Next, the present invention will be explained in more detail with reference to Examples. .

Examples 1 to 5 The predetermined resins shown in Table 1 were melt-kneaded using an extruder, introduced into a three-layer inner adhesive type modular die, and then subjected to infusion molding at a blow ratio of 4.3 to obtain a thick Sa 40
Table 1 shows the results of the evaluation of moldability for each of the three-layer laminated soil 1 and the obtained fill 7, each having a thickness of 1/l.

Comparative Examples 1 to 3 In Table 1, the same measurements as in Example 1-5 were carried out on the laminated film. The results are shown in Table 1.

7/ //' //' / 7/ , /′ *1 Indicates the ratio of inner layer/intermediate layer/outer layer.

*2 Film impact method (The film was fixed in a ring shape and punched out using a pendulum with a 1-inch impact type, and the energy/L energy required was measured. Used.)) *3 Based on JIS Z 1702.

*4 JIS Z 0208 (400C, 90% J Ml) (Based on 4, *5 Ml: 1.5,
Density: 0.956. MFR, :24*6 Ml
: 5.8, Density: 0.967, MFR:
20*7 Ml: ]', 0, density: 0.
965. At MFI: 30*8 Ml: 0.0
5. Density: 0.955. MFR: 100*1
0 Ml: 3.0, Density: 0.920 Here, Ml, density, and MFR are JIS K 67
60.

248-

Claims (1)

[Scope of Claims] 1. A laminate comprising a layer (A) made of low-density polyethylene and a layer (B) made of high-density polyethylene having a melt flow ratio of 10 to 60 laminated on both sides thereof. 2. High-density polyethylene has a melt index of 0.1
~2oy/lo min, density 0', 945~0, 970g
/cnr3.