JPH01110954A - Manufacture of laminated film or sheet - Google Patents

Abstract

PURPOSE:To obtain a laminated film or sheet which is superior in an external appearance or smoothness of the surface, by a method wherein polyolefine resin having specific physical properties and a base material are extruded and laminated. CONSTITUTION:A matter whose density and melt index are respectively 0.920-0.930g/cm<3> and 2-8g/10min. and a molecular weight distribution index to be shown by the product of (melt index value) and (melt tension value) falls within a range of 15-35 is used as polyolefin resin. Ramified state low-density polyethylene, linear low-density polyethylene, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer and ethylene-acrylic acid ester copolymer are mentioned as the polyolefine resin to be used. The polyolefine resin may be a matter obtained by modifying the sane by performing graft reaction with unsaturated carboxylic acid or its anhydride, for example, anhydrous maleic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a laminated film or sheet by extrusion laminating a polyolefin resin onto a base material.

More specifically, the present invention relates to a method for producing a laminated film with improved surface appearance (eg, transparency or gloss) and surface smoothness using a polyolefin resin having specific physical properties.

[Prior art]

Conventionally, a method for manufacturing a laminated film or sheet by extrusion laminating a polyolefin resin onto a base material is to extrude the molten polyolefin resin from a T-die attached to an extruder, and then press the extruder to extrude the polyolefin resin from a T-die attached to the extruder. This is done by bonding the molten resin to a base material via a pressure roll.

In the above extrusion lamination method, the molten film extruded from the T-die causes a so-called neck-in phenomenon in which the density of the molten resin film decreases with respect to the width of the T-die due to the surface tension of the molten resin. Furthermore, during extrusion lamination, the molten resin film causes wobbling or meandering in the drawing direction, which is the so-called draw resonance phenomenon, making it difficult to obtain a uniform film thickness and causing variations in the width of the molded product. was there.

As a method to avoid problems such as neck-in phenomenon and draw resonance phenomenon during extrusion lamination molding,
Generally, resins with a wide molecular weight distribution and many long chain branches are used, that is, resins with a large molecular weight distribution index, which will be described later.

[Problem that the invention seeks to solve]

However, resins with a large molecular weight distribution index have large melt elasticity (elastic rings in melting behavior), and when extruded from the lip of the die, they tend to cause rough skin due to melt fracture, resulting in a white band-like appearance on the surface of the laminate molded product. There is a problem in that a striped pattern appears and fine irregularities are formed on the surface, impairing the appearance (especially transparency or gloss) and surface smoothness of the surface of the molded product.

[Means for solving problems]

In order to solve the above-mentioned problems of the conventional extrusion lamination method using polyolefin resin, the inventors of the present invention have conducted extensive studies and found that low-density polyethylene with specific physical properties was used as the polyolefin resin to be extrusion laminated to the base material. By using, the appearance of the surface (especially transparency or gloss)
The inventors have also discovered that a material with significantly improved surface smoothness can be obtained, and have completed the present invention.

That is, the gist of the present invention is that when producing a laminated film or sheet by extrusion laminating a polyolefin resin onto a base material, the polyolefin resin has a density of 0.9.
20-0.930g/d1 melt index is 2~g
g7'io minutes, and (melt index value) x
The molecular weight distribution index expressed as (value of melt tension) is 15~
The present invention relates to a method for producing a laminated film or sheet, characterized in that a film or sheet having a molecular weight of 35 is used.

The polyolefin resins used in the present invention include branched low-density polyethylene (high-pressure low-density polyethylene), linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene- Examples include (meth)acrylic acid ester copolymers. Further, these polyolefin resins may be modified by grafting reaction with an unsaturated carboxylic acid or its anhydride, such as maleic anhydride.

The above polyolefin resin has a density of 0.920-
0.93017 cr&, preferably O0?22~O0
2g1i/cfl, melt index 2-19
710 minutes, preferably in g/10 minutes, and the molecular weight distribution index (hereinafter α ) is 15 to 35, preferably 20
~30.

If the density is less than the lower limit, the surface smoothness of the laminated product will be poor, and if it is higher than the upper limit, the surface smoothness of the laminated product will be poor, and the adhesion to the base material will also be poor, which is not preferable.

Further, if the melt index is less than the lower limit, high-speed moldability will be poor and the surface smoothness of the laminate product will be significantly reduced, and if it is higher than the upper limit, the surface smoothness of the laminate product will be poor, which is not preferable. Furthermore, if the molecular weight distribution index is below the lower limit, the neck-in will be excessive and a draw resonance phenomenon will occur, resulting in poor laminate formability, while if it is higher than the upper limit, the surface of the laminate molded product will become rough. This is not desirable.

In the present invention, the melt index is JIS-KA7
It is a value measured in accordance with the melt index measurement method of AO (polyethylene test method) at /9o'c1, /15kg, and the density is a value measured in accordance with JIS K&'140 [and further Melt tension is JI of resin
2! from the nozzle used in the method for measuring the melt index of S K 6760 when extruding at 140°C, O12 g/min, and pulling at a hull speed of 11 L/min! This is the tension measured at a distance of 'm.

There are no particular restrictions on the base material used in the present invention, and all base materials used in normal extrusion lamination can be used, including thermoplastic resins with film-forming ability, paperboard, kraft paper, and thin paper. Paper such as, metal foil such as aluminum foil, copper foil, tin foil, etc. can be used. Examples of the thermoplastic resin include high density polyethylene, medium and low density polyethylene, polypropylene, polybutene-11 ethylene-propylene copolymer, ethylene-
Polyolefin resins such as vinyl acetate copolymer, propylene-butene-ethylene terpolymer, polyvinyl chloride,
Polyvinylidene chloride, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymer, styrene resins such as polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene ternary copolymer, nylon 6, nylon 6- 6. Nylon b-10. Nylon II
, amide resins such as nylon 12, ester resins such as esters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate resins, and thermoplastic resins such as vinylon. These base materials can be appropriately selected depending on the purpose and use. For example, industrial materials include cloth sheets, kraft paper, and polystyrene sheets; materials for light packaging include polyethylene, polypropylene, nylon, etc., and gas barrier base materials include nylon, polyethylene terephthalate, Examples include ethylene-vinyl acetate copolymer and polyethylene. In addition, transparent and rigid substrates such as biaxially stretched polyethylene terephthalate sheets, polycarbonate sheets, polypropylene sheets, and polystyrene sheets are also used for applications that require optical properties such as parts of optical equipment and special photosensitive materials. /-) etc. are used.

If the base material is a thermoplastic resin, it may be uniaxially or biaxially stretched.

In the present invention, in order to extrusion-laminate the polyolefin resin described above on the base material, it is possible to directly extrusion-laminate the base material, or to increase the adhesive strength between the base material and the polyolefin resin, corona is applied to the adhesive surface of the base material. Extrusion lamination may be performed after performing known surface activation treatments such as surface treatment, flame treatment, and anchor coating treatment. The anchor coating treatment may be carried out by applying a known anchor coating agent such as polyurethane-based alkyl titanate-based, polyethyleneimine-based, isocyanate-based, etc. to the surface of the base film or sheet.

The above-mentioned extrusion lamination molding can be carried out using a known method and apparatus. For example, the polyolefin resin is heated from the extruder to the resin temperature.

The molten thin film is formed into a molten thin film by extrusion at ~3'1O<0>C, and the molten thin film is guided to a pressure roll, and the above-mentioned base film whose adhesive surface is untreated or subjected to the above-mentioned surface activation treatment and also drawn to the pressure roll. This is done by crimping and laminating the sheet.

[Examples] Hereinafter, the present invention will be described in detail by way of Examples, but the present invention is not limited thereto unless it departs from the gist thereof.

Example 1 / 0.3 μm on the adhesive surface of a biaxially stretched polyethylene terephthalate sheet with a thickness of 0.3 μm! r KW/rr? /m, and subjected the adhesive surface of this base material to M I = 3.
．． Evening/i/10 minutes, density = o, q a 6i/cnl
sMolecular weight distribution index = 2S1 Melting point = /l''t'C high pressure low density polyethylene resin at resin temperature 315℃, 110μ
Made of thick extruded laminate. Neck-in during molding,
Table 1 shows the results of measuring draw resonance, transparency and smoothness of the obtained film.

Example 7 The same procedure as Example 7 was carried out except that the polyethylene resin shown in Table 1 was used. The results are shown in Table 1.

Comparative Examples 1 to 5 High-pressure low density polyethylene (Comparative Examples -/ and -5), linear low density polyethylene (Comparative Example -3, S), and medium density polyethylene (Comparative Example -2) shown in Table 1 as polyethylene resins ) was used in the same manner as in Example 1.

The results are shown in Table 1.

Note that neck-in, presence or absence of draw resonance, transparency, and smoothness in the above Examples and Comparative Examples were evaluated by the following methods.

■ Neck-in 1000m wide T-die is squeezed into the OO group by decker Shear gap / 1OIII + 1 take-up speed 100m /
- The length of the narrowing in the θθ order of the laminate width of the extrusion laminated product was measured.

(2) Draw Resonance Extrusion lamination was carried out under the above conditions, and the presence or absence of citroresonance was determined by observing the presence or absence of deflection of the molten web over an evening period.

■Transparency The haze value was measured by the method of ASTM D-1003.

■Smoothness A rod-shaped fluorescent lamp 2 m away was seen through the molded product so that the flow direction of the fluorescent lamp and the molded product were perpendicular to each other, and the degree of undulation of the image was ranked as follows.

A: Hardly any waving is observed B: Waving is clearly observed C: Severe waving [Effects of the Invention] According to the present invention, by extrusion laminating a polyolefin resin having specific physical properties and a base material, A laminated film or sheet with excellent surface appearance (particularly transparency or gloss) or surface smoothness can be obtained.

Therefore, the laminated sheet obtained using the method of the present invention using a transparent and rigid base material, such as biaxially stretched polyethylene teletumerate sheet or polycarbonate, can be used as parts of optical equipment, special photosensitive materials, and photographic paper. It is suitably used for applications such as , and the surface layer of Goshin printing substrates.

Claims (1)

[Claims] (1) When manufacturing a laminated film or sheet by extrusion laminating a polyolefin resin onto a base material, the density of the polyolefin resin is 0.920 to 0.930 g.
/cm^3, a melt index of 2 to 8 g/10 minutes, and a molecular weight distribution index expressed by (melt index value) x (melt tension value) in the range of 15 to 35. A method for manufacturing laminated films or sheets.