JPS6084345A - Preparation of trans-1,4-polyisoprene film - Google Patents

Abstract

PURPOSE:To prepare the titled film at an extremely high film-forming speed (about 10m/min or higher), by melt-extruding a raw polymer having specified organic compounds incorporated therein. CONSTITUTION:About 0.1-1pt.wt. one or more of 1,3:2,4-bis(methylbenzylidene) sorbitol, dibenzylidenesorbitol, and sodium bis(4-t-butylphenyl)phosphate are incorporated into 100pts.wt. trans-1,4-polyisoprene. The obtained composition is melt-extruded at about 180-220 deg.C using a T-die, etc., and immediately wound around a cooling roll to be cooled and solidified, thus forming a film. By the above-mentioned process, a thin film with a thickness of about 20mu or less can be manufactured easily at a high film-forming speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a film of trans-1,4-polyisoprene by melt extrusion.

Trans-1,4-polyisoprene has a structure as shown in formula 1 below, and is a well-known synthetic rubber.
-The type of polymerization is different from that of polyisoprene (formula ■).

However, in reality, products containing about 0.2 mol% of 3,4 bonds as shown in the following formula (■) are commercially available, and trans-1,
The number of 4 bonds is about 99 mol%.

-CH2-CH'.

CH, -C・・・・・・・・・・・・(Ill) H2 A film made of the above trans-1,4-polyisoprene, or mainly made of trans-1,4-polyisoprene, and preferably A film made of a mixture of 10 mol% or less (however, the proportion of monomers) of compatible resins, such as cis-1,4-polyinprene, polybutadiene, etc. (In the present invention, the meaning includes both of these films) Trans-1,4-polyisoprene film (also called trans-1,4-polyisoprene film) has the unique property of being able to be cross-linked with sulfur, and when heated, it shrinks more than other general-purpose films, causing it to shrink unnaturally. It can be used in applications where these properties can be advantageously utilized, such as films for shrink wrapping. however,
The production of trans-1,4-polyisoprene films is considerably more difficult than the production of films of other common film-formable thermoplastic JFT resins. That is, although trans-1,4-polyisoprene has a low melting point of 45°C, the viscosity of the melt is high, so when forming a film, it is necessary to reduce the viscosity to a level that allows extrusion molding, so the extrusion temperature is set at about 180°C. ~220
℃, but in addition to the fact that the resin is extruded at such a high temperature that the melting point rises slowly, the crystallization rate of this resin is quite slow, so it is difficult to form a film using a T-die film-forming stone. Then, the cooling capacity becomes insufficient. As a result, the formed film is difficult to peel off from the cooling roll and is prone to wrapping.

Therefore, in order to sufficiently promote cooling and crystallization and prevent the above-mentioned draught, the film take-up speed must be significantly reduced. For example, when producing a film with a thickness of 50 μm,
The take-off speed was limited to about 4.5+o/min (for other resins, such as polyethylene, about 21), but it is possible to take off at speeds of 0 m7 min or more. ). In addition, if the difference between the melting point of the resin and the extrusion temperature is large, it will take a long time for the molten resin film to solidify during extrusion, which may cause accidents due to deformation or cutting of the resin film before assimilation, especially in the case of thin films. easy. Therefore, the thickness of the formable film is typically 40
μ is the limit, and it was extremely difficult to manufacture a film thinner than that.

The present invention has succeeded in solving the problems associated with the production of trans-1,4-polyisoprene film as described above, and the molding raw material resin is 1,3:2,4.
- Bis(methylbenzylidene) sorbitol, dibenzylidene sorbitol or bis(4-t-butylphenyl) sodium phosphate are mixed.

When manufacturing a trans-1,4-polyisoprene film by the manufacturing method of the present invention, each of the above additives may be used alone or two or more types may be used in combination. The preferred usage amount (total amount when two or more types are used together) is 10 resins.
0 parts by weight, in each case, the range is from 0 to 1.0 parts by weight, particularly preferably from 1,2 to 0.7 parts by weight. In order to facilitate the process, it is desirable to first prepare a masterbatch of the resin and additives at a high (H) ratio before mixing.

trans-1,4-polyisoprene or cis-
The method for forming a film of a mixture with 1,4-polyisoprepevobutadiene and the like mixed with the above additives is arbitrary, but
Preferred is the method using T-gui. A suitable extrusion temperature is about 180 to 220°C. 170℃
Below, the melt viscosity of the resin is too high and it is difficult to form a film.
Furthermore, at temperatures above 230°C, the resin undergoes thermal decomposition. The molten resin film extruded from the T-Guy is immediately brought into contact with a cooling roll to be cooled and solidified.

According to the manufacturing method of the present invention using the above-mentioned additives, although the mechanism of action of the additives is not yet clear, the solidification of the molded 1#J fat film is rapid, and therefore the film formation rate can be reduced to approx. 10
It is possible to increase the speed up to m/min, and furthermore, it is easy to manufacture a thin film of about 20 μm, which was previously impossible to manufacture.

The present invention will be explained below with reference to Examples. Note that the "limit take-up speed" shown in the examples refers to the speed at which the formed film is
The "thickness limit" refers to the maximum take-up speed at which the film can be peeled off from the cooling roll without causing edge breakage or wrapping around the cooling roll, and the "thickness limit" refers to the maximum speed at which the film can be peeled off from the cooling roll without causing film breakage in the molten state. This means the thinnest film thickness that can be removed without any damage.

Example 1 Trans-1,4-polyisoprene with a Mooney viscosity of 30 (ML, +4.100'C) and a density of 0.96 was
1,3:2,4-bis(methylbenzylidene) sorbitol (hereinafter referred to as DTS) was extruded from a T-die through a 65mm diameter extruder and cooled on a cooling roll to obtain a 50μ thick film at 65°C. ), dibennolidene sorbitol (hereinafter abbreviated as DBS) or sodium bis(4-butylphenyl) phosphate (hereinafter SBP)
The influence of O (abbreviated as 1.0 parts per 100 parts of fat) on the maximum withdrawal speed and thickness was investigated. The results are shown in Table 1.

Table 1 Additives Limit withdrawal speed (+n/min) Limit -Yr
(, lsu DTS 11 23 SBP 10 20 DBS 9.5 25 None 4.0 4Ll Example 2 0.5 part of the two types of additives used in Example 1 were mixed at a ratio of 1:1. A test was conducted in the same manner as in Example 1 to produce a trans-1,4-polyisoprene film.

The results are shown in Table 2.

Table 2 Additives Limit take-up speed (7 minutes) Thickness limit (horn) D
TS+SBP 10 25 DTS+DBS 10 25 SBP+DBS 10 2'5 Example 3 As used in Example 1, 5 mol% of 1,2-polybutadiene with a density of 0.91 was added to trans-1,4-polyisoprene.
A trans-1,4-polyisoprene film was produced in the same manner as in Example 1, except that the mixture (ratio for seven months) was used as the raw material resin and 0.5 part of DTS was used as an additive. We conducted a test. The results are shown in Table 3.

Table 3 Additives Limit withdrawal speed (Kan/Momtsu Thickness limit (lJ) D
TS 12 18 None 4.5 40

Claims (1)

[Claims] In producing a film of trans-1,4 to polyisoprene by melt extrusion, the raw materials trans-1,
4-Polyisoprene with x, I3: 2.4-bis(methylbenzi'lidene) sorbitol, dibenzylidene sorbitol or bis(4-t-butylphenyl) sodium phosphate is mixed with trans-1.
, 4-Production method of polyisoprene film.