JPS5835133B2 - NETSUKASOSEIKOBUNSIFIRUMUNOSEIZOUHOU - Google Patents

Description

[Detailed description of the invention] The present invention is a method for producing a thermoplastic polymer film.

More specifically, it suppresses the reduction in width, non-uniformity of thickness, precipitation of white powder on the surface of the casting drum, etc. that occur when the molten thermoplastic polymer is cooled and solidified on the surface of the casting drum and formed into a film. The aim is to provide a method for reducing the deterioration of the working environment when

Methods for producing films by applying organic substances to the surface of a casting drum are known.

For example, Japanese Patent Application Laid-open No. 49-99160 discloses that the surface tension of the casting drum is 5 at boiling point of 150 to 220°C.
It has been proposed to apply alcohol with a boiling point of 150 to 220°C and a surface tension of 50 dynes/cm or less, and an organic liquid other than alcohol to the surface of the casting drum. It is proposed to apply.

However, these alcohols and other organic liquids have a strong odor and are often flammable, which not only significantly deteriorates the working environment but also makes them uneconomical.

Furthermore, JP-A-50-76173 proposes applying an oily substance to the surface of the casting drum, but it is difficult to completely remove the oily substance from the film in subsequent steps, and Post-processing of film
For example, it is not preferable because it brings about disadvantageous results when applying magnetic paints, photosensitive agents, adhesives, laminating adhesives, etc.

As a result of extensive research into a method that does not have these drawbacks and suppresses the reduction in width during film formation, non-uniformity in thickness, precipitation of white powder on the surface of the casting drum, etc.
A mixture of "organic liquid at a temperature of 00°C or more and 230°C or less" and water, in which water accounts for 10 weight upwind of 90 weight φ or less, and the contact angle of the mixture with the casting drum is 40° or less The inventors have discovered that it is sufficient to apply a liquid mixture having the following properties onto the surface of a casting drum, and have arrived at the present invention.

That is, in the present invention, when a thermoplastic polymer melt extruded from a die is cooled and solidified on a rotating casting drum whose surface is coated with a liquid to form a film, the liquid has a boiling point of 100°C. A mixture of an organic liquid with a temperature of at least 230°C or less and water, the water being 10% of the mixture.
This is a method for producing a thermoplastic polymer film characterized by using a mixture having a weight of 90 degrees or less on the upwind side and a contact angle of the mixture with respect to a casting drum of 40 degrees or less.

The thermoplastic polymer used in the method of the present invention may be any polymer as long as it can be melt-formed into a film, including polyolefin,
Polyamide, polyester, polycarbonate, etc. are preferred1
Polyethylene terephthalate is particularly preferred.
It is often used.

In the method of the present invention, a liquid is applied to the surface of a rotating casting drum used to cool and solidify a thermoplastic polymer melt extruded from a goo.

This is to suppress reduction in the width of the film, non-uniformity in thickness, and precipitation of white powder on the surface of the casting drum during film formation.

In the method of the present invention, the liquid distributed on the surface of the casting drum is a mixture of "an organic liquid with a boiling point of 100°C or more and 230°C or less" and water, and the water is 10% of the mixture.
A material having a weight upwind of 90 φ or less and a contact angle of the mixture with the casting drum of 40° or less is used.

If the boiling point of the organic liquid is lower than 100° C., it tends to evaporate faster than water, which is undesirable because it tends to reduce wetting of the drum and film.

In the past, when the boiling point of the organic liquid was higher than 230°C, the organic liquid that adhered to the formed film could not be sufficiently removed even after it was made into a product through post-processes such as stretching and heat treatment. I don't like it because it remains.

The organic liquid preferably has a boiling point of 200° C. or lower.

Regarding the mixing ratio of water and the organic liquid, if the content of water in the mixture is less than 10% by weight, the amount of organic liquid will inevitably be too much, resulting in strong odor and flammability, which will deteriorate the working environment. On the other hand, if the amount of water exceeds 90% by weight, it becomes impossible to sufficiently suppress the decrease in the width of the film during film formation, which is not preferable.

In particular, it is preferable that the water content be 85 gw leeward.

Preferably, the mixture is a solution in which water and the organic liquid are well mixed.

Furthermore, the mixture must have a contact angle of 40° or less with respect to the casting drum.

If the contact angle is larger than 40°, it is difficult to uniformly apply the coating onto the casting drum, resulting in uneven coating, which is not preferable.

Since the contact angle is preferably small, a small amount (approximately 0.1 weight coefficient or less) of a surfactant may be added to the mixture.

Moreover, two or more kinds of the organic liquids may be used in combination.

Examples of organic liquids preferably used in the method of the present invention include methyl cellosolve, ethyl cellosolve, improvir cellosolve, n-propyl cellosolve, isobutyl cellosolve, n-butyl cellosolve, isoamyl cellosolve, and diethylene tallicol ethyl ether.

In order to apply the mixture of water and the organic liquid to the surface of the rotating casting drum in the method of the present invention, the mixture is cast on the area where the molten polymer film or the solidified film is not attached. The coating may be applied to the entire surface of the drum (gold mine) or the surface to which the thin film is to be adhered (width to which the thin film is to be adhered) using a known coating means such as spraying, a doctor knife, a brush, or the like.

Alternatively, a considerable effect can be obtained by applying the mixture only to the portions of the drum surface where the left and right ends (both ends in the direction perpendicular to the extrusion direction) of the film are attached.

The method of the invention includes known means for helping the polymer melt adhere to the casting drum, such as blowing a uniform stream of air onto the melt, suctioning air interposed between the melt and the drum, Alternatively, means such as electrostatically applying an attractive force between the melt and the drum can be used in combination.

According to the method of the present invention, when a polymer melt is extruded from a die and cooled and solidified on the surface of a casting drum to produce a film, the film width is reduced, the film thickness becomes uneven, and white powder is formed on the drum surface. It has the advantage of suppressing the adhesion of dirt, etc., is safe and economical, and does not worsen the working environment.

The value of the contact angle employed in the method of the present invention is based on the measurement method shown below.

[Measurement method of contact angle] Place the liquid to be measured on a flat target solid held horizontally with a contact circle diameter of 1 to 2 mm.
Drip so that

A goniometer captures this droplet image as seen from the horizontal direction, and adjusts it so that one end of the arc is at the center of the goniometer.

The contact angle should be read with a protractor 1 minute after dropping.

The ambient conditions at the time of measurement were a temperature of 20°C and a relative humidity of 60%.

Example 1 Polyethylene terephthalate with an intrinsic viscosity (measured at 25°C using O-chlorophenol as a solvent) of 0.620 was melted by heating at 280°C in an extruder, extruded through an extrusion die with a width of 320 mm, and the surface temperature was 40°C. It was rapidly cooled on the surface of a casting drum (diameter 634 m) and made into a 170 μ thick film at 15 m/ffl? I picked it up at a speed of 7+.

At this time, a cloth pad impregnated with a mixed solution of 50 parts by weight of water and 50 parts by weight of ethyl cellosolve is brought into contact with the entire surface (kanayama) of the rotating casting drum, so that the mixed solution is applied to the surface of the casting drum. It was applied to.

As a result, the width of the formed film was 275, and the thickness variation rate was ±17.

Even after one hour of continuous operation, no white powder was observed on the surface of the casting drum.

There was only a slight odor of the solvent.

After the obtained unstretched film was heat-treated for 10 seconds at a longitudinal stretching temperature of 85° C., a longitudinal stretching ratio of 3.4 times, and a transverse stretching temperature of 100° C., no water or organic liquid remained on the film surface.

Example 2 Water 9 was used as the liquid applied to the surface of the casting drum.
Film formation, biaxial Stretching and heat treatment were performed.

The width of the produced unstretched film was 252 rran, and the thickness variation rate was 21.8%.

Even after one hour of continuous operation, no white powder was observed on the surface of the casting drum.

Moreover, no odor of the solvent was detected.

Water and organic liquid remained on the film surface after the biaxial stretching heat treatment, causing unevenness, and no difference was observed between the film surface and the film surface to which no liquid was attached.

Comparative Example 1 Film formation, biaxial stretching, and heat treatment were performed in the same manner as in Example J except that no liquid was applied to the surface of the casting drum.

The width of the formed unstretched film was 182 mm, and the thickness variation rate was -JH2.5%.

From this result, it can be seen that in this example, the width of the unstretched film relative to the width of the extrudate was significantly reduced, and the rate of variation in the thickness of the film was also large, compared to the example.

Furthermore, white powder was observed to adhere to the surface of the casting drum 5 minutes after the start of continuous operation.

Comparative Example 2 Film formation, biaxial stretching, and heat treatment were performed in the same manner as in Example 1 except that n-decane was used as the liquid applied to the surface of the casting drum.

The width of the formed unstretched film was 255 mm, and the thickness variation rate was ±18%.

Even after one hour of continuous operation, no white powder was observed on the surface of the casting drum.

It was observed that a small amount of organic liquid remained on the film surface after the biaxial stretching heat treatment.

In addition, the odor of n-decane was very strong during the film forming process, and even though the casting drum was forcibly evacuated from above, the odor was still quite strong.

Claims (1)

[Claims] 1. When the thermoplastic polymer melt extruded from a die is cooled and solidified on a rotating casting drum with liquid distributed on its surface and formed into a film, the liquid has a boiling point of 100°C or higher and 230°C or lower. of an organic liquid and water, the water being present in the mixture on a
1. A method for producing a thermoplastic polymer film, characterized in that the mixture has a weight of φ or less of 0 and a contact angle of the mixture with a casting drum of 40° or less.