JPH08158158A - Biodegradable resin fiber and its production - Google Patents

Abstract

PURPOSE: To obtain a biodegradable resin fiber having practical mechanical properties by melt-spinning the blend of poly β-hydroxybutyric acid with polycaprolactone, cooling the spun fiber, and subsequently subjecting the cooled fiber to a multistage drawing treatment and a relaxing treatment. CONSTITUTION: The pellets of highly pure poly β-hydroxybutyric acid in an amount of 10-80 pts.wt., and 90-20 pts.wt. of polycaprolactone are blended with each other, melted in a monoaxial extruder, spun through a spinneret, introduced into a -50 to 15 deg.C liquid bath whose liquid surface is placed below the spinneret, cooled and subsequently wound as a non-woven fiber. The formed fiber is subjected to a multi-stage drawing treatment comprising the first step having a drawing ratio of 2.0-10.0 times and the >=second steps having that of 1.1-3.0 times at a drawing temperature of 4-55 deg.C, and subsequently to a relaxation treatment of 0.01-15% to obtain the biodegradable resin fiber having mechanical properties such as tensile strength, elastic modulus and knot strength in practical levels.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to clothing, fishing nets and agriculture.
The present invention relates to a biodegradable resin fiber that can be used for ropes, strings, sheets, etc. for civil engineering.

[0002]

2. Description of the Related Art Generally, clothes, fishing nets, ropes, strings, sheets for agricultural and civil engineering use polyesters such as polyethylene terephthalate (PET), nylon 6
Polyamides represented by are mainly used.
However, in recent years, from the standpoint of environmental protection, the reuse of plastics has been called for, and in the field of applications where reuse is not possible, there is a strong social demand for the use of biodegradable resins that are completely decomposed by the action of microorganisms. ing.

Poly β-hydroxybutyric acid (hereinafter abbreviated as PHB) is generally manufactured by a fermentation method using a microorganism, and polycaprolactone (hereinafter abbreviated as PCL) is manufactured by a chemical synthesis. PHB and PCL have the biodegradability that they are completely decomposed by the action of microorganisms widely distributed in the natural world, and because they are thermoplastic, they are actively investigated for use in various applications by existing molding methods. Is being done.
However, it is known that PHB lacks thermal stability in a molten state and is difficult to mold, and the molded product obtained has a small elongation and is hard and brittle. In addition, PHB that has been sufficiently crystallized is difficult to draw, and it is difficult to produce a yarn having a practical opportunity property by melt spinning and drawing. On the other hand, PCL has a large elongation but a melting point of 60.
Since it is as low as ℃, it has the drawback of low heat resistance.
For this reason, PHB and PCL have excellent biodegradability to meet the social demands for environmental protection, but they are still insufficiently used in textiles for clothing and fishing nets. I haven't arrived.

[0004]

DISCLOSURE OF THE INVENTION The present invention aims to provide a fully biodegradable resin fiber which is stretched and has high practicality by mixing PHB, which has been difficult to be stretched, with PCL having a low melting point. Let's take that issue.

[0005]

The inventors of the present invention have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention relates to a biodegradable resin fiber composed of PHB and PCL, and having PHB in the range of 10 to 80 parts by weight, and when producing the biodegradable resin fiber, a melted yarn is used. The temperature of the liquid to be cooled is -50 to 15 ° C, preferably -50 to 10 ° C or lower, and the stretching bath temperature is 4 in the subsequent stretching step.
To 55 ° C., preferably 15 to 55 ° C.

Generally, as a method for stretching a resin,
(A) A method of stretching an amorphous portion of a resin to be stretched at a glass transition point or higher, and (b) a method of stretching a crystalline portion immediately below a melting point are known. Method (a) is polycaprolactam (nylon 6), polyhexamethylene adipamide (nylon 6)
6), PET and the like, and the method (b) is applied to polyolefin-based polymers such as polyethylene and polypropylene. When the PHB yarn is produced at room temperature, it seems that stretching just below the melting point is preferable because it has a high degree of crystallinity, but in practice, it is stretched and fractures before crystal orientation. Further, Japanese Patent Application Laid-Open No. 58-82723 discloses a method of applying a compressive force to reduce the thickness of the PHB sheet and then stretching, but in the case of fibers, it is very difficult to adopt this method. Therefore, we tried the following method when stretching the biodegradable resin obtained by mixing and melting PHB and PCL. The temperature of the liquid for cooling the melt spinning is -50 to 15 ° C,
PHB is preferably set to -50 to 10 ° C or less.
The crystallinity of PCL is lowered, and at the same time, PCL is a condition for promoting crystallization. On the other hand, the temperature of the stretching tank when stretching,
By setting the temperature to 4 to 55 ° C., preferably 15 to 55 ° C., the PHB portion is stretched above the glass transition point, and at the same time, PC
The L portion is stretched just below the melting point. As a result, the biodegradable resin fiber excellent in mechanical performance was produced without excessive breakage in the drawing step, and the present invention was completed.

PHB-containing bacterial cells used in the present invention are, for example, genus Alcaligenes, genus Azotobacter, genus Methylobacterium, genus Nocardia,
It can be produced by a known fermentation method using a bacterium of the genus Pseudomonas. Next, PHB
Are separated and purified from bacterial cells containing these PHBs.
Regarding the method for separating and purifying PHB from bacterial cells, for example, US Pat. Nos. 3,036,959, 4,101,533, and 3,
275610, EP 15123, pyridine, methylene chloride, 1,2-propylene carbonate,
A method using a solvent such as chloroform and 1,2-dichloroethane is described, and Japanese Patent Application No. 5-323019.
Describes a method in which bacterial cells are crushed with a high-pressure homogenizer, PHB is separated, and the separated PHB is treated with an oxygen-based bleaching agent. The PHB used in the present invention may be used in combination with a lipid compound such as triacetin as a plasticizer and an inorganic / organic compound such as boron nitride as a nucleating agent.

The cross-sectional shape of the fiber of the present invention is not particularly limited, but it is usually a round or flat cross-sectional shape.

The following method can be exemplified as one of the embodiments of the present invention. 10 to 80 parts by weight PHB
In contrast, after blending 90 to 20 parts by weight of PCL,
Melt spinning is performed using a normal screw type extruder. In melt spinning, the spinning temperature is 180 to 190 ° C., spinning is performed through a spinneret, and the liquid level is within 2.0 m below the spinneret surface −50 to 15 ° C., preferably in a cold water bath at 10 ° C. or lower, or After being taken up in an organic solvent and cooled, it is once wound to obtain an unstretched yarn, or continuously without once being wound, and stretched in one or two or more stages according to specific conditions, and then, The relaxation treatment is performed at a relaxation rate of 15% or less. As the liquid for cooling the melt spinning, water, glycerin, liquid paraffin, silicone oil, polyethylene glycol, diethylene glycol or the like is used.

The stretching process is carried out in the usual dry heat air bath, warm water bath,
A stretching means such as a steam bath or an organic solvent bath can be used. The first stage draw ratio is 2.0 to 10 times, the draw ratio after the second stage is about 1.1 to 3.0 times, the relaxation rate is 15% or less, and the total draw ratio is 2.2 to 30 times. To be The stretching temperature is in the range of 4 to 55 ° C, preferably 15 to 55 ° C. If the drawing temperature exceeds 55 ° C, the P
There is a risk that the CL portion will dissolve and stretching will not be possible, and if the stretching temperature is less than 4 ° C, PHB will not crystallize, and in this case also stretching will not be possible. For the relaxation treatment, a dry heat air bath or an organic solvent bath, a hot water bath or a steam bath kept at a temperature of 4 to 55 ° C. is used, and the relaxation rate is 15% or less. When the relaxation rate is larger than 15%, problems such as wrapping around the roller due to slack of the fiber occur and it is difficult to stably and continuously wind.

[0011]

EXAMPLES The present invention will be described below in greater detail by giving Examples, but the present invention is not limited thereto. still,
Properties such as the strength and elastic modulus of the fibers in the examples are JIS L 10
13 Measured in accordance with "Test method for chemical fiber filament yarn". However, the measurement temperature of Examples 1 to 3 and Comparative Example 1 was 23 ° C., and the measurement temperature of Example 4 was 50 ° C.
C., and the measurement temperature of Comparative Example 2 was 23.degree. C. and 50.degree.

EXAMPLE 1 Protomonas e, a bacterium, which has been deposited at the Institute of Biotechnology, Institute of Biotechnology, AIST
xtorquens) K (consignment number: FERM BP-354
Using 8), continuous culture was performed aerobically using methanol as a carbon source. The culture conditions are a culture temperature of 32 ° C. and a culture pH of 6.
5. The average residence time was 40 hours, and continuous culture was performed so that the nitrogen supply rate was the rate-determining factor for bacterial cell growth. According to recent literature, this bacterium is methylobacterium (Methylobact
erium) (IJ Bousfield and P.
N. Green; Int. J. Syst. Bacteriol., 35,209 (1985), T. Ur
akamiet al .; Int.J.Syst.Bacteriol., 43,504-513 (199
3)). The bacterial cells obtained by continuous culturing are the above-mentioned Japanese Patent Application No. 5-3.
According to the method for separating and purifying PHB described in 23019, after crushing with a high-pressure homogenizer, PHB was centrifuged, and the separated PHB was first treated with protease and then treated with hydrogen peroxide to obtain high-purity PHB. The PHB was pelletized using a screw type extruder. The PHB pellets thus obtained and PCL (Placcel H-7 manufactured by Daicel Chemical Co., Ltd.) were blended so as to be PHB 20 parts by weight, and melted using a single-screw extruder. Spinning temperature is 1
It was spun through a spinneret at 87 ° C., taken up in a water bath at a temperature of 8.4 ° C. having a liquid surface at a position 50 mm below the surface of the spinneret, wound once, and stretched. Stretching is carried out in two stages of stretching and one stage of relaxation. As a stretching means, a warm water bath with a temperature of 30 ° C. is used in the first stretching region, a dry hot air bath of 50 ° C. is used in the second stretching region and a relaxation region of 50 ° C. is used. A dry heat air bath was used, and the stretching conditions were a first stretching ratio of 4.0, a second stretching ratio of 1.17, and a total stretching ratio of 4.5. Manufacturing speed is 53.3m
/ Min. 161 denier monofilament was obtained by the above method. Table 1 shows the tensile performance of the obtained biodegradable resin fiber at 23 ° C.

Example 2 The PHB pellets and PCL shown in Example 1 were mixed with PHB4.
Blending was carried out so as to be 0 parts by weight, and the mixture was melted using a single-screw extruder. The spinning temperature was set to 185 ° C., the product was spun through a spinneret, taken up in a water bath at a temperature of 8.8 ° C. having a liquid level 35 mm below the surface of the spinneret, wound once, and stretched. Stretching is carried out in two stages of stretching and one stage of relaxation,
As the stretching means, a warm water bath at a temperature of 30 ° C. is used in the first stretching region, a dry heat air bath of 50 ° C. is used in the second stage stretching region, and a dry heat air bath of 50 ° C. is used in the relaxation region. Draw ratio 2.
5, the second draw ratio was 1.85, and the total draw ratio was 4.5. The production speed was 53.9 m / min. A 202 denier monofilament was obtained by the above method. Table 1 shows the tensile performance of the obtained biodegradable resin fiber at 23 ° C.

Example 3 The PHB pellets and PCL shown in Example 1 were mixed with PHB7.
Blending was carried out so as to be 0 parts by weight, and the mixture was melted using a single-screw extruder. The spinning temperature was set to 185 ° C., the product was spun through a spinneret, taken up in a water bath at a temperature of 9.0 ° C. having a liquid level 35 mm below the surface of the spinneret, wound once, and stretched. Stretching is carried out in two stages of stretching and one stage of relaxation,
As the stretching means, a warm water bath at a temperature of 30 ° C. is used in the first stretching region, a dry heat air bath of 50 ° C. is used in the second stage stretching region, and a dry heat air bath of 50 ° C. is used in the relaxation region. Draw ratio 2.
0, the second draw ratio was 2.28, and the total draw ratio was 4.5. The production speed was 54.2 m / min. By the above method, 315 denier monofilament was obtained. Table 1 shows the tensile performance of the obtained biodegradable resin fiber at 23 ° C.

Comparative Example 1 The PHB pellets shown in Example 1 were melted using a single screw extruder. The spinning temperature was set to 185 ° C., the product was spun through a spinneret, and the product was taken up in a water bath at a temperature of 6.3 ° C. having a liquid level at a position 65 mm below the surface of the spinneret, wound once, and stretched. Stretching is carried out in two stages of stretching and one stage of relaxation. As a stretching means, a warm water bath with a temperature of 30 ° C. is used in the first stretching region, a dry hot air bath of 50 ° C. is used in the second stretching region and a relaxation region of 50 ° C. is used. A dry heat air bath is used, and the stretching conditions are a first stretching ratio of 4.0,
The second draw ratio was 1.13 and the total draw ratio was 4.5.
The production speed was 54.2 m / min. 247 denier monofilament was obtained by the above method. Table 1 shows the tensile performance of the obtained biodegradable resin fiber at 23 ° C. The knot strength could not be measured because it was below the detection limit of the measuring machine.

Example 4 50% by weight of the PHB obtained in Example 1 was added to 50% of the monofilament.
The tensile performance at ° C was measured. The tensile performance is shown in Table 2.

Comparative Example 2 PCL (Placcel H-7 manufactured by Daicel Chemical Co., Ltd.) was melted using a single screw extruder. The spinning temperature was set to 185 ° C., the product was spun through a spinneret, taken up in a water bath at a temperature of 8.3 ° C. having a liquid level at a position 50 mm below the spinneret surface, once wound up, and then stretched. Stretching is carried out in two stages of stretching and one stage of relaxation. As a stretching means, a warm water bath with a temperature of 30 ° C. is used in the first stretching region, a dry hot air bath of 50 ° C. is used in the second stretching region and a relaxation region of 50 ° C. is used. A dry heat air bath was used, and the stretching conditions were a first stretching ratio of 4.0, a second stretching ratio of 1.17, and a total stretching ratio of 4.5. The production speed was 53.9 m / min. By the above method, 205 denier monofilament was obtained. Table 2 shows the tensile performance of the obtained biodegradable resin fiber at 50 ° C.

[0018]

[Table 1] Table 1 Tensile performance of biodegradable resin fiber at 23 ° C PHB / PCL Tensile strength Elastic modulus Knot strength Knot strength (weight part / weight part) (gf / D) (kgf / mm ² ) (gf / D) Retention (%) Example 1 20/80 5.7 205 205 5.1 89 Example 2 40/60 3.2 240 2.9 91 Example 3 70/30 1.5 180 180 1.4 93 Comparison Example 1 100/0 0.32 15 Not measurable-

[0019]

[Table 2] Table 2 Tensile performance of biodegradable resin fiber at 50 ° C PHB / PCL Tensile strength Tensile strength Elastic modulus Elastic modulus (weight part / weight part) (gf / D) Retention rate (%) (kgf / mm ² ) Retention rate (%) Example 4 20/80 1.8 32 82 40 Comparative Example 2 0/100 0.84 19 11 11

[0020]

EFFECTS OF THE INVENTION According to the present invention, it is possible to produce a biodegradable fiber having practical mechanical properties by the melt spinning method using an ordinary screw type extruder. This makes it possible to provide fibers that are used for applications that cannot be recycled and fibers that are used for disposable applications.

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Claims (4)

[Claims] 1. The biodegradable resin comprises poly β-hydroxybutyric acid and polycaprolactone, 10 to 80 parts by weight of poly β-hydroxybutyric acid and 9 parts of polycaprolactone.
Biodegradable resin fibers in the range of 0 to 20 parts by weight. 2. The temperature of the liquid for cooling the melted yarn in the melt spinning process for producing the undrawn yarn is -50 to 15 ° C.,
In the step of subsequently stretching the unstretched yarn, the stretching temperature is set to a range of 4 to 55 ° C., which is composed of poly β-hydroxybutyric acid and polycaprolactone and contains 10 to 80 parts by weight of poly β-hydroxybutyric acid. 9 caprolactone
A method for producing a biodegradable resin fiber in the range of 0 to 20 parts by weight. 3. The step of drawing an undrawn yarn is carried out by multi-step drawing of two or more steps, the first step draw ratio is 2.0 to 10 times, and the draw ratio of the second step and thereafter is 1.1 to 3. The method for producing a biodegradable resin fiber according to claim 2, which is carried out at a rate of 0.0 times. 4. A relaxation rate of 0.01 after drawing an undrawn yarn.
The method for producing a biodegradable resin fiber according to claim 2 or 3, wherein the relaxation treatment is performed at -15%.