JPS60242055A - Laminated film - 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 colored laminated film mainly used for packaging and the like.

Conventionally, packaging films include polypropylene (hereinafter referred to as PP), low-density polyethylene produced by high-pressure process (hereinafter referred to as LDFB), straight-line low-density polyethylene produced by low-pressure process (hereinafter referred to as LLDPFi), and high-pressure polyethylene (hereinafter referred to as LLDPFi). Single-layer films such as HDIE (hereinafter referred to as HDIE) are often used.

However, although the above PP film is strong and has good gloss,
LDPJ has poor low temperature impact strength and heat seal strength.
C, LLDPK film has (fj impact strength, heat seal strength is strong but has weak elasticity, HDPK film has strong elasticity and high impact strength, but heat seal strength is low and has almost no gloss.) In addition, when the monolayer film is colored, it is necessary to mix the coloring agent into the entire film, resulting in the inconvenience that a large amount of expensive coloring agent is used.

The present invention hastened to address the above-mentioned circumstances, and was developed by using a coextrusion method to glue PP and polyethylene, which are generally considered not to bond together. The object of the present invention is to provide a laminated film that is vividly colored, has a gloss, has a high elasticity, and has good impact strength and heat seal strength.

The present invention will be explained below.

The PP used in the laminated film of the present invention is a propylene-based polymer such as a propylene monopolymer, an ethylene-propylene random copolymer, an ethylene-propylene block copolymer, or a mixture thereof. In addition, polyethylene with a density of 0.9301/cc or less,
Low-density polyethylene with long chain branches (L
LLDPJ) or directly exposed polyethylene (Ll, DPI) with short chain branching produced by a low-pressure process is used, but because of its good coloring, LLDPJ! i is preferable.

In addition, the melt flow index of the above PP (hereinafter referred to as MF■
It is called. , rTS, 6758) is 129/lO
M or less is preferable, and the melt index of LDPE (hereinafter referred to as MTζ.6760 in 5-8) is lOp/mm
The following is preferable, and Mr of LL and DPJC is 4 fl
/10 RAW or less is preferable, and if it exceeds this, film forming becomes difficult.

In addition, titanium white, titanium white,
#Blue, carbon black, etc. - can be widely used.

The laminated film according to the present invention is made by first mixing polyethylene and a colored tin with pure gold using a masterbatch method or a tri-blend method, and then mixing this with propylene.
It is manufactured by a coextrusion method such as a die method or an inflation method.

The above-mentioned coextrusion may be performed by adhesion inside the die or by adhesion outside the die.

However, in the extrusion lamination method, if the cooling roll used is mirror-finished, it will fuse, so a satin-finished roll must be used. As a result, the surface of the film becomes rough and loses its luster, making it impossible to produce a film that is sharp and brittle.

The laminated film formed by the above-mentioned coextrusion preferably has a thickness of 10 μm or less because the thinner the colored polyethylene layer is within the range that can be coextruded, the more the color shine is maintained and the stiffness becomes stronger.

In addition, in the above-mentioned method, the polypropylene is not colored, but it may be slightly colored to form a katahiro film. However, if the coloring of the polypropylene J- is stronger than the color of the polyethylene layer, the color of the entire laminated film will not be bright, so it is preferable to remove only the polyethylene layer.

Next, the present invention will be specifically explained by showing examples and comparative examples.

Example 1゜vigL: 0.8811/cc, MFr: 9g/
l Ortrm's uncolored PP (propylene homopolymer) and density: 0.918 fl/CC, MT:
1. OJ/l LLDPI in O order! As a coloring factor for i,
Using titanium white pigment, rutile type R-680 (trade name), pure gold with LLDpg/pigment: 100 10.7 parts, die diameter = 100, die mk: 20
Coextruded by inflation method at 0°C, blow-up ratio = 2.5, pPom thickness: 15μ, LLPDP
A laminated film having an E layer thickness of 15 μm was prepared.

Example 2゜As polyethylene'Mk-: 0.9201i/
cc.

A laminated film was produced using exactly the same operations and conditions as in Example 1, except that LDPB of Mr:2p/lO was used.

Comparative Example 1゜aIi::0.88&/cc, Myr:9. og7
The same material as in Example 1 was made of pure gold in four proportions as a color chain for PP of cc, and GM was carried out by the inflation method at a die diameter of 100 mm and a die temperature of 180°C, and the thickness was 30 mm.
Comparative Example 2 in which a single layer film of μ was prepared: 0.918 Ji' / C'C1M D
1-0. ! A single-layer film was produced using the same operations and conditions as in Comparative Example 1, except that LLDPE of //10 ttup was used and the die temperature was 190°C.

Comparative Example 3 Density L: 0.920 i/cc, M T: 3 g/
Using LDPffi of l 0urs, die temperature: 190
A single-layer film was produced using the same operations and conditions as in Comparative Example 1, except that the temperature was changed to ℃.

Comparative Example 4゜density: 0.95p/cc, MT: 0.05J/10 using HDPK, die mat: 20oC.
A single layer film was produced using the same operations and conditions as in Comparative Example 1.

The physical property values of the above-mentioned fire example, comparative example & scrap film, and single layer film were measured and shown in Table 1.

Table 1) 1) L L D p z side 2) LDPFi side 3)
2y/d/sec, single side heating m degree 2t Example 1, Comparative example 2...190°CExample 2, Comparative example 3...170°C Comparative example 1...230'C Comparative example 4 ...200°C 4) Comrade L L D P v 5) Comrade 1 of LDPK
From the table, it can be seen that the laminated film of the present invention has no physical defects and is vague. In addition, the amount of pigment used for a single no film is only about 50 cm.

As mentioned above, the laminated film according to the present invention has good area reduction gloss, is strong, has poor low temperature strength and heat seal strength, and if pigments are mixed into polyethylene, a colored film can be produced. This product has many advantages, such as requiring less coloring. Applicant: 1964 Denko Co., Ltd.

Claims (1)

[Claims] TL characterized by being formed by co-extruding polypropylene and polyethylene having a density of 0.930, lit/cc or less and containing a colorant at a higher concentration than the polypropylene.
T-layer film.