JPS6169431A - Stretching method of poly(beta-hydroxybutyric acid) molded product - Google Patents

Abstract

PURPOSE:To enable to stretch the titled molded product in the ordinary stretching method by a method wherein a molded product consisting of polymer, the main ingradient of which is beta-hydroxybutyric acid, is heated up to the specified temperature and, after that, cooled down and kept on cooling for the specified period of time. CONSTITUTION:beta-hydroxybutyric acid polymer is extracted from aqueous cellulose suspension with 1,2-dichloroethane and added to methanol/water solution in order to precipitate. The resultant precipitate is washed with methanol and dried and finally pressed at 190 deg.C into the shape of a preform. The preform is heated at a temperature, which is below but not lower by 40 deg.C than its melting point, or preferably at a temperature ranging from that lower by 5 deg.C than the melting point to that lower by 30 deg.C than the melting point, and cooled down to below 100 deg.C or preferably to a temperature ranging from 70 deg.C or below to 0 deg.C or higher and kept at the temperature for 1-120sec, preferably for 5-60sec. Finally, the preform is stretched by the percent of stretch of 120% or more, preferably 150% or more, more preferably 200% or more. The preform cooled after heat treatment can be stretched in the ordinary stretching method. The ordinary stretching operation is done normally under the temperature ranging from room temperature to 10 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION a) Technical Field The present invention relates to a method for stretching a molded product made of poly(β-hydroxyacetic acid) and/or a copolymer thereof.

b) Prior art poly(β-hydroxybutyric acid) and/or copolymers thereof (
Hereinafter, these may be collectively referred to as PH8), for example, E tlrODean ChelRicalN
As shown in EWS June 28, 1982, page 17, it has various uses as a polymer exhibiting unique properties such as microbial degradability and piezoelectricity.

Furthermore, since these polymers are not produced through petrochemistry but are produced using microorganisms, they are expected to be useful polymeric materials considering future petroleum shortages.

However, as shown in JP-A No. 58-82723, PHB is a melt-molding method applied to ordinary synthetic polymers.
Even if it is attempted to improve the physical properties of a product formed using a molding method such as wet molding by stretching it, it is difficult to do so using normal methods. For example, a special method is considered necessary, such as stretching the molded product after pressure rolling.

C) Solution The inventors of the present invention have repeatedly investigated the possibility of stretching using a normal stretching method rather than using such a special method. The inventors have discovered that stretching is possible using a normal stretching method, and have arrived at the present invention.

d) Structure of Hatsuro When stretching a molded product made of a polymer whose main component is β-hydroxyacetic acid, the molded product is heated to a temperature below its melting point and not lower than the melting point by 40°C or more. This is a method for stretching a poly(β-hydroxybutyric acid) molded product, which is characterized by heating, then holding at a temperature of 100° C. or lower for 1 to 120 seconds, and then stretching 1.2 times or more.

The PHB referred to in the present invention is, for example, JP-A No. 57-150393.
These are polymers or copolymers as shown in Japanese Patent Application Laid-open No. 58-69224 and the like. In other words, those having -0-G H+ CR3+CH2-G O- repeating units produced by microorganisms, or -0-0RI R
2soCR3R"-)n Co-(n is O or regular, ・
It is a copolymerized product selected from Ro, Ro, Ro, Ro number, hydrocarbon group, halo or hydroxy-substituted hydrocarbon group, hydroxy group, halogen atom, hydrogen atom), and this copolymerization ratio is usually less than 50 mol%.

In the present invention, such PH8 is made into a preform and then stretched. Any method may be used to produce this preform, such as a melt molding method, a wet molding method, a dry molding method, etc. However, when the melt molding method is used, the obtained preform must be crystallized. Uncrystallized preforms are not preferred because they deform or break during the practice of the present invention.

In the present invention, such a preform is heated to a temperature below the melting point and not more than 40°C below the melting point, preferably at a temperature of (melting point -5°C) to (melting point -30°C), and then heated for 10 minutes.
Cool to 0°C or lower, preferably 70°C or lower, and cool to 1°C or higher.
After holding for 120 seconds, preferably 5 to 60 seconds, it is stretched 1.2 times or more, preferably 1.5 times or more, more preferably 2 times or more. The heating time and heating temperature vary depending on the amount of copolymerization, the shape of the preform, etc., but it is desirable to adjust the heating time and temperature appropriately by preliminary tests. The same applies to the cooling temperature for 1 hour.

If the heating temperature is higher than the melting point, it will naturally melt, and if the heating temperature is 40° C. or more lower than the melting point, the stretching ratio cannot be increased, which is not preferable. Also, if the cold W temperature is too high or the cooling time is short,
So-called flow stretching occurs and strength cannot be increased. If the cooling time is not too long, the stretching ratio will not increase.

Heating is usually carried out under a constant length, but may be carried out with stretching less than 1.5 times. Cooling is also normally performed under no tension.

The preform cooled after heat treatment may be stretched by a normal stretching method, and the temperature at this time is usually room temperature to 100°C.
It is ℃.

e) Examples Example 1 Alcaiaenes eutrophus mutant strain (A1caiaenes eutrophus
mut'ant) S 801/C5 (NG I
β-Hydroxybutyric acid polymer produced by aerobic cultivation of 811599) was extracted from an aqueous cell suspension with 1,2-dichloroethane, precipitated by addition to a methanol/water solution, washed with methanol, and dried. was press-molded at 190°C to obtain a film-like preform with a thickness of 0.2 m.

After this preform was left at room temperature for one day, it was heat treated in silicone oil at 160°C for 5 seconds, and then at 25°C.
After being kept in air for 10 seconds, it was uniaxially stretched 8 times as it was. The resulting material had a strength of 190 MPa. Further, the melting point of this product was 174°C as a result of differential thermal analysis at a heating rate of 20°C/min. .

Comparative Example 1 An attempt was made to stretch the preform of Example 1 after leaving it at room temperature for one day, but it could only be stretched 1.1 times, and the strength was 25.
It was MPa. Further, even when heat treated at 130° C. for 5 seconds, the stretching was only 1.3 times, and the strength was 31 MPa.

Comparative Example 2 Immediately after the heat treatment in Example 1, an attempt was made to stretch the film 8 times, but the film was cut and could not be stretched.

Examples 2 and 3 The results of using the β-hydroxy archaic acid/copolymerized polyβ-hydroxybutyric acid obtained by using the glucose/propionic acid mixture in place of glucose in Example 1 are shown in the table.

(Left below) Example 4 The polymer of Example 1 was melted at 190°C, and 1#ll11
Thread extruded from a nozzle with a diameter of about 100 mm and dried for several days, and a film obtained by dissolving it in chloroform, casting it on a glass plate and drying naturally, were heat treated, cooled, and stretched in the same manner as in Example 1, resulting in a melt-extruded thread. The strength of the cast film was +50 MPa, and the strength of the cast film was +30 MPa.

Patent applicant: Teijin Kaisha Ltd.).

／、：＼ Representative Patent Attorney 1） Jun Hiroshi 1
1. ．． ．． j1. ．． ．． l：＼、：゛・ し

Claims (1)

[Claims] (1) When stretching a molded product made of a polymer whose main constituent is β-hydroxybutyric acid, the molded product is heated to a temperature below its melting point and no lower than 40°C below the melting point, and then heated to 100°C. A method for stretching poly(β-hydroxybutyric acid) molded articles, which comprises holding the following temperature for 1 to 120 seconds and then stretching 1.2 times or more.