JPH03176122A - Manufacture of corrugated film - Google Patents

Abstract

PURPOSE:To enable formation of a favorable wave form on a raw fabric sheet or a film, by a method wherein at the time of roll stretching treatment of the raw fabric sheet or the film, the film is pressed against a stretching roll with nip rolls in a specific form. CONSTITUTION:A raw fabric film 1 is temperature-controlled to a temperature suitable for stretching with preheating rolls 2, 2', 2'' and stretched with differ ence between a number of revolutions of a feeding-in roll 3 and those of a take-off roll 4. A draw ratio is made at least 1.5 times, preferably at least 2 times. Shaping of a wave form is performed by a method wherein the surface of nip rolls 5 or 6 is formed into uneven state and the same is pressed against the film on a feeding-in roll 3 or the take-off roll 4. A difference between the maximum value and minimum value of the diameter of the rolls is made prefer ably at least 500 mum in relation to a change ratio of a widthwise direction of the surface of the nip rolls 5 or 6 and a matter comprised of an elastic material such as neoprene rubber or EPD rubber or silicone rubber is preferable as the quality of the material or the nip rolls 5 or 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing corrugated films. Specifically, the present invention relates to a method for producing a film in which the film itself is wavy (hereinafter referred to as a wavy film) using a thermoplastic resin.

[Conventional technology and its problems]

Conventionally, methods for producing corrugated films using thermoplastic resins include extruding molten resin through a T-shaped die and cooling it with a cooling drum having a corrugated die to form a corrugated film; There is a method of manufacturing a wavy film by making the die cap wavy. However, these methods require the preparation of a large number of molds or cooling drums depending on the shape of the film, and creating these molds requires a large amount of money, making it difficult to support high-mix, low-volume production. There was a problem.

In view of the above-mentioned problems, the inventors of the present invention have made extensive studies on a method for producing a corrugated film, and have found that when roll-stretching a raw sheet or film, the film can be pressed against a stretching roll using a specially shaped nip roll. Knowing that it is possible to form good corrugations on anti-sheets or films,
The present invention has been completed by finding a method that solves the conventional problems and easily provides a wavy film at low cost.

That is, the gist of the present invention is a method for producing a corrugated film from a thermoplastic sheet or film, in which a sheet or film in a heated state is stretched between rolls at a stretching ratio of 1.5 times or more, and during this stretching, A method for producing a wavy film, characterized in that a nip roll whose surface is uneven in the width direction is provided near a feeding stretching roll and/or a taking-off stretching roll, and the nip roll is pressed against a sheet or film. Exists.

A specific example of the method of the present invention will be explained using the drawings.

FIG. 1 is a schematic diagram of an example of the apparatus used to carry out the method of the invention.

In the figure, 1 is the original film, 2.2', 2'' is the preheating roll,
3 is a feed roll, 4 is a take-off roll, and 5.6 is a nip roll.

The raw film 1 is supplied either directly or once wound up as a film extruded from an extruder. The raw film 1 is temperature-controlled (heated) to a temperature suitable for stretching by preheating (temperature-controlling) rolls 2゜2', 2'', and stretched by the difference in rotational speed between the feed roll 3 and the take-up roll 4. be done.

A nip roll 5 or 6 is provided near the feed roll 3 or take-up roll 4 during this stretching, and corrugations are applied to the film before or after stretching.

The corrugation is achieved by forming the surface of the nip roll 5 or 6 into an uneven shape and pressing it against the film on the feed roll 3 or the take-up roll 4.

Examples of the shape of the nip roll 5 or 6 include those shown in FIG.

It is sufficient to press either one of the nip rolls 5 or 6 against the film, but it is also possible to press both. At this time, it is also possible to produce a complex waveform by using rolls of different shapes as the nip rolls 5 and 6, respectively.

The change rate in the width direction of the roll surface of the nip roll 5 or 6 is preferably such that the difference between the maximum value and the minimum value of the roll diameter is 50
The thickness is preferably 0 μ or more, preferably 1 mm or more. If it is smaller than 500μ, a uniform wave pattern may not be formed on the film, which is not desirable.

The material of the nip roll 5 or 6 is neoprene rubber, EPD.
Preferably, it is made of an elastic material such as M rubber or silicone rubber. In particular, elastic materials with a hardness of JIS K6301A of 65" or more, preferably 75° or more are preferably used. If the hardness is less than 65°, the roll made of the elastic material will be severely worn, and the elastic material will be too soft, so the This makes nipping difficult and the entire width of the film is nipped, resulting in a wavy film.

The raw film may be any thermoplastic resin that is commonly used for making films, such as polyolefin resins, polyamide resins, and polyester resins.

The stretching ratio is 1.5 times or more, preferably 2 times or more.

If the stretching ratio is small, the difference in deformation between the nipped portion and the non-nipped portion of the film will be small, and a wavy film will not be obtained.

It is preferable that the stretching gap between the rolls be narrow in order to obtain a clear waveform. The higher the deformation speed of the film, the better the corrugated film will be. Preferably, the stretching is performed at a rate of 500%/min or more. The stretching temperature may be any general condition normally employed in the stretching treatment of the resin film used. The original thickness of the film may be any thickness as long as it can be stretched, but is preferably 2 mm.
It is about ~50μ.

Although the stretched film may be wound up as is, it is preferable to heat-set it by heat treatment (annealing) at a temperature higher than the stretching temperature, from the viewpoint of dimensional stability of the film.

[Examples] Examples are shown below, but the present invention is not limited to the following examples unless the gist of the invention is exceeded.

Example 1 Linear low density polyethylene (L-LDPE)
(Melt index: 1g/10min, density: 0.92
Og/cm' ) 80 parts, branched low density polyethylene (LDPE) (Mll, 5 g/10 min, ρ: 0.921
g/cm3) 20 parts peresotobrentoshi, 50 parts
Using a mm (screw diameter) extruder, the resin temperature was 250°C.
A film having a width of 800 mm and a thickness of 300 microns was obtained by T-die molding.

This film was stretched three times at a preheating temperature of 80° C. and by changing the circumferential speeds of rolls 3 and 4 based on the stretching process flow shown in FIG.

The nip roll was made of EPDM rubber and had a hardness of 70°, and was used as the nip roll 5 of the feed roll.

The nip roll 5 used had the shape shown in FIG. 2 (a).

In order to evaluate the waving state of the film, the film obtained in Example 1 was slit to a width of 5001 mm, one end of the film was fixed, the film was hung between two rolls (1 m), and the other end was slit. A weight was attached to the end and a tension of 20 g/cm was applied. The difference between the maximum and minimum unevenness values in the width direction of the film was obtained and the degree of waviness was determined. The results are shown in Table-1.

Example 2 The same raw materials as those used in Example 1 were used, and the diameter was 250 m.
A tubular film with a thickness of 100 μm and a fold width of 1200 mm was obtained by extrusion from a circular die with an annular slit of m and a gap of 1.2 mm. Using a nip roll made of EPDM rubber with a rubber hardness of 80'' in the shape shown in Figure 2 (C),
It was stretched 2.5 times at a temperature of 85°C. The nip roll was provided on the feed roll.

The wavy state is shown in Table 1.

Comparative Example 1 A film was stretched in the same manner as in Example 1 except that the film was stretched by 2° and 5 times using nip rolls having a uniform diameter and a hardness of 65°. The results are shown in Table 1.

Comparative Example 2 A stretched film was obtained in the same manner as in Example 1 except that the stretching ratio was changed to 1.2 times. The results are shown in Table 1.

Table 1 [Effects of the Invention] According to the method of the present invention, a corrugated film can be obtained stably and with high efficiency without requiring expensive equipment, and it is suitable for producing a wide variety of small quantities of corrugated films. is very good in practice.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of an apparatus used to carry out the method of the present invention, and FIG. 2 shows an example of the shape of a nip roll. In the figure, 1 is the original film, 2.2' and 2'' are the preheating rolls, 3 is the feeding roll, 4 is the take-up roll, and 5.6 is the nip roll.

Claims (1)

[Claims] (1) A method for producing a corrugated film from a thermoplastic sheet or film, in which a heated sheet or film is stretched between rolls to a stretching ratio of 1.5 times or more, and a feeding stretching roll and a A method for producing a corrugated film, comprising: providing a nip roll whose surface is uneven in the width direction near a drawing roll for taking-off, and pressing the nip roll against a sheet or film.