JPH01156062A - Translucent propylene resin multilayer composite film - Google Patents

Abstract

PURPOSE:To improve gloss and water resistance, by laminating a film composed of an olefinic resin having a specific composition and a surface layer composed of polypropylene to at least the single surface of a biaxially stretched resin film having a specific composition. CONSTITUTION:A biaxially stretched film consisting of 75-95wt.% of a propylene resin and 25-5wt.% of high density polyethylene is formed and a film formed from a composition consisting of 80-95wt.% of a propylene resin, 10-0wt.% of an olefinic resin such as high density polyethylene and 20-5wt.% of a fine inorg. powder is laminated to at least the single surface of said film. Further, a uniaxially stretched film composed of a propylene homopolymer or propylene random copolymer is laminated to said film to obtain a composite film. The opacity measured value of this composite film according to JIS.P.813 is 3-25%.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a translucent propylene film useful as a base material for book covers, translucent labels, illuminated signboards and posters, OHPs, thermal X-ray films, or thermal transfer recording materials. The present invention relates to a resin multilayer composite film.

The composite film of the present invention has excellent gloss, water resistance, and is translucent.

[Prior art]

Traditionally, book covers have been made of semi-transparent paraffin paper that has been sandblasted on one side.

However, since the strength is weak and easy to tear, a biaxially stretched film of polypropylene containing fine inorganic powder is used as the base layer, and an l-axis stretched film of polypropylene containing a larger amount of fine inorganic powder than the base layer is used as the surface layer. The opacity (JIS P-8138
) is 30-38%, surface gloss (JIS P-814
2) 5 to 7% is YUPO TP than egg oil synthetic paper■
It is sold and used as G (product name).

YUPO TPG is also used as tracing paper for illuminated signboards, posters, and drafting. Since this Yubo TPG is also intended for pencil writing, the surface layer contains a large amount of inorganic fine powder. Therefore, the glossiness is low at 5 to 7%, and further improvement in glossiness is desired for book covers.

In addition, it has an opacity of 30-38%, making it good as a tracing paper, convenient for copying, and easy to use. It is desired that the opacity be further reduced for water-resistant films used to seal transparent labels and box bodies containing confectionery such as cookies and chocolates.

[Means to solve problems]

In the present invention, the surface layer has a high crystallinity (50 to 8
5%) By using a propylene homopolymer or a propylene random copolymer, the transparency and gloss of the composite film are improved.

Even though the biaxially stretched film layer, which is the thickest base layer in the composite film, does not contain inorganic fine powder, it is transparent in an amount that has no substantial effect on opacity (3% or less in 3 layers). Improve your sexuality.

By containing an inorganic fine powder in the intermediate layer between the base material layer and the surface layer (uniform layer to be described later), the intermediate layer (A) is heated at a high temperature so that fine voids are not generated in the intermediate layer (A) during stretching. The opacity of the resulting composite film is adjusted to 8 to 20% by stretching the film (orienting the film).

That is, the present invention contains 75 to 95% by weight of propylene resin,
A biaxially stretched resin film made of 25 to 5% by weight of high-density polyethylene is used as the base material layer (4), and the base material layer (4)
(a) propylene resin 80-9 on at least one side of the
5% by weight, (b) 10-0% by weight of an olefin-based resin selected from high-density polyethylene, ethylene/vinyl acetate copolymer, and low-density polyethylene, and (e) 20-5% by weight of inorganic fine powder. A uniaxially stretched product of a laminate of a film (B) made of a resin composition and a film C) of a propylene homopolymer or a propylene random copolymer is formed such that the opening of the uniaxially stretched product of the latter propylene homopolymer film is A composite film laminated to form a surface layer, the composite film conforming to JISP-8
To provide a translucent propylene-based resin multilayer composite film having an opacity of 3 to 25% as measured in accordance with the JIS P-8142 standard, and a glossiness of the surface layer (from the Q side measured in accordance with the JIS P-8142 standard) as 65 to 95%. It comes out.

(Manufacture of Composite Film) The composite film of the present invention is produced by melt-kneading the resin composition forming the base layer (4) using an extruder, feeding it into a trap, and extruding it into a sheet.

Next, this resin sheet is cooled to a temperature lower than the melting point of the propylene resin of the base layer, for example, 40 to 85 ° C., and heated again to the softening point of the propylene resin of the base layer.
Stretch 3 to 10 times in the machine direction. By this stretching, the base layer film is oriented in the longitudinal direction.

Subsequently, using separate extruders, the intermediate layer forming resin composition (A) and the surface layer forming resin O are melt-kneaded, fed to a die with a 1-stand, and then co-extruded into a sheet to form the above-mentioned vertical Melt lamination (laminate) on both sides or one side of stretched resin sheet
, f3) at least 10 times lower than the melting point of the propylene resin in the layer.
The film is stretched 4 to 12 times in the transverse direction at a temperature higher than 0.degree.

], the composite film of the present invention is manufactured by subjecting it to an annealing treatment if necessary, and then slitting the edges.

The layer structure of this composite film is as shown in FIG. (A)/(8)-4
Layer and groove structure is typical, but if necessary, other resin layers, such as adhesive layer (S) or gas barrier layer, may be placed between each layer.
Alternatively, it may be provided on the surface layer. For example, a film layer of gas barrier polyamide, polyethylene terephthalate, or saponified ethylene/vinyl acetate copolymer may be provided between the intermediate layer and the adhesive layer, or one of the surface layers (usually called the back layer depending on the application). This means laminating a low-temperature heat-sealable film on top.

(Composition of each layer) (N base layer (a) Propylene resin 75-95% by weight High density polyethylene 25-5% by weight (B) Intermediate layer (a) Propylene resin 80-95% by weight (b)
High-density polyethylene, ethylene/vinyl acetate copolymer,
Olefin resin selected from low density polyethylene 1
0-0 weight f1% (e) Inorganic fine powder 5-2
0 weight i% 0 surface layer propylene homopolymer (homopolymer 1?-) Note that an adhesive layer with the following composition may be provided between the base layer and the intermediate layer (mepropylene resin). 8-94.5% by weight C) High-density polyethylene 5-15% by weight (C') Inorganic fine powder 0.5-5% by weight.

However, the base material layer (4) is oriented to increase the stiffness of the waist. In order to prevent the formation of fine voids due to stretching, the base material layer does not contain substantially (3% by weight or less) inorganic fine powder. .

High density polyethylene, low density polyethylene, ethylene
Compared to vinyl acetate copolymers and the like, propylene resins have a higher melting point, higher rigidity, and higher crystallinity.

The composition of the adhesive layer is mainly composed of propylene resin in order to improve the adhesive strength between the base material layer and the intermediate layer (A). Preferably high density polyethylene, low density polyethylene,
The adhesion strength is further improved when the ethylene/vinyl acetate copolymer is contained in an amount of 5 to 15% by weight.

The content of the inorganic fine powder in the composition of the intermediate layer (@) is a major factor in determining the opacity of the resulting composite film along with the thickness of each layer. Therefore, the inorganic fine powder is contained in a proportion of 5 to 20% by weight. Propylene resin provides rigidity, and polyethylene resin provides stretchability.

The surface layer (C) preferably uses a crystalline propylene homopolymer in order to impart gloss to the composite film. High gloss cannot often be obtained with propylene-ethylene block copolymers.

Moreover, this layer does not substantially contain inorganic fine powder. The propylene-based random copolymer is mainly composed of propylene (over 800% by weight), with ethylene and butene.
Examples include random copolymers having a crystallinity of 50 to 85% obtained by copolymerizing one or more monoolefins such as 1,4-methylpentene-11hexene.

As the propylene resin constituting the base layer, adhesive layer, and intermediate layer, propylene homopolymers, the above-mentioned random copolymers, propylene/ethylene block copolymers, maleic anhydride kraft polypropylene, and the like can be used.

In addition, as an inorganic fine powder, the average particle size is 0.03 to 16
Micron heavy calcium carbonate, calcined diatomite, clay, silica, talc, zeolite, titanium oxide, barium sulfate, etc. can be used.

(Physical Properties of Composite Film) The opacity of this composite film is 3 to 25%, preferably 5 to 20%, and the gloss is 65 to 95%. When the opacity is less than 3%, the appearance is no different from that of a transparent film made of stretched polypropylene film, and there is no decorative effect for book covers, labels, etc. In addition, for thermal print films, it is necessary to place an opaque object on the back side in order to view the image.

If the opacity exceeds 25%, problems may arise, such as making it difficult to see through the contents of a bottle or box, or making it difficult to see through the letters on the cover of a book.

If the gloss is less than 65%, the decorative effect will be poor when used as labels, book covers, etc. Furthermore, a gloss level exceeding 95% is difficult in terms of molding.

The thickness of the entire composite film is 40 to 500 microns, preferably 80 to 250 microns.
Accounts for 30-80% of the total thickness, the thickness of the adhesive layer (S) is 0.2-10 microns, and the thickness of the surface layer 0 is 0.5-80%.
lO micron, the intermediate layer Q3) is 40 to 40 times the thickness of the base material layer.
100% is common.

The surface layer 0 prevents the inorganic fine powder of the intermediate layer (A) from falling off from the composite film.

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

Production Example of Multilayer Film Example 1 (1) A mixture (g) of 900 weights of homopolypropylene (melting point 164°C) with a melt index (MI) of 0.8 and 8 weights of high-density polyethylene (g) was melted and mixed in an extruder. It was extruded into a sheet from a die and cooled by a cooling device to obtain a non-stretched sheet. This sheet was heated to 155° C. and then stretched 5 times in the machine direction.

(2) homopolypropylene 0 with M I 4.0;
Composition a), which is a mixture of 86.5% by weight of polypropylene with an MI of 4.0, 101 L of calcium carbonate with an average particle size of 1.5 units, and 3.5% by weight of high-density polyethylene, is melt-kneaded in a separate extruder. Then, the sheets that were laminated and coextruded in a die were laminated on both sides of the 5 times stretched sheet of (1) so that C) was on the outside, and then this five layer laminate was heated to 185°C and then extruded in the lateral direction. The film was stretched 7.5 times to obtain a five-layer film.

(3) The surface of this five-layer laminated film was subjected to corona discharge treatment, and the thickness of each film of C)/CB)/(A)/(B)/C) was 5/20/50/20/5.
A laminate with a five-layer structure of microns was obtained.

The physical properties of this five-layer laminated film having a wall thickness of 100 microns were determined as follows.

Opacity (JIS P-8138) 12% Glossiness (JIS P-8142) 79% Density
0.94 f/ad smoothness (TD
/MD) 1300 seconds/1900 seconds curl
None Examples 2 to 3, Comparative Examples 1 to 2 Five layers with the physical properties shown in Table 2 were prepared in the same manner as in Example 1, except that the composition of the intermediate layer forming composition (B) was changed as shown in Table 2. A composite film was obtained.

Table 2 Application example 1 Green content made of glass with an embossed surface Fill the translucent interior of 40CC with beer,
After the stopper was applied, a barcode was printed on the five-layer translucent composite film with a wall thickness of xoo microns obtained in Example 1 as a label, and a transparent acrylic solvent-based adhesive was applied to the body of the bottle. It was pasted together.

I was able to see through the label and see through the beer inside the bottle.

Application example 2 Transparent polyvinyl chloride hollow molded container (inner volume aoo
v) After filling a bottle with a liquid detergent colored pale green and capping it, use the 100 micron thick translucent composite film obtained in Example 3 as a label with a barcode and characters printed on it. It was attached to the body of the bottle using a transparent rubber emulsion type adhesive.

The liquid detergent inside the bottle could be seen through this label.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the composite film of the present invention.

Claims (1)

[Scope of Claims] 1) A biaxially stretched resin film made of 75 to 95% by weight of propylene resin and 25 to 5% by weight of high-density polyethylene is used as the base material layer (A); ) on at least one side of (a) propylene resin 8
0 to 95% by weight, (b) 10 to 0% by weight of an olefin resin selected from high density polyethylene, ethylene/vinyl acetate copolymer, and low density polyethylene, and (c) 20 to 5% by weight of inorganic fine powder. A uniaxially stretched product of a laminate of a film (B) made of an olefin resin composition and a film (C) of a propylene homopolymer or a propylene random copolymer is a uniaxially stretched film of the latter propylene homopolymer film. A composite film in which the material (C) is laminated as a surface layer, the composite film has an opacity of 3 to 25% as measured according to the standard of JISP-81 38, and the surface layer has an opacity of 3 to 25%. (
C) A translucent propylene-based resin multilayer composite film having a glossiness of 65 to 95% as measured from the side according to JISP-8142.