JP7289475B2 - Method for producing biodegradable fiber - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act [Publisher name] The Textile Machinery Society of Japan May 24 [Meeting name] The 71st Annual Conference of The Textile Machinery Society of Japan [Date] June 2, 2018 [Meeting name] Tokyo Institute of Technology, School of Materials Science and Engineering, Materials Science, Doctoral Internship, Interim Presentation of Master's and Doctoral Dissertations [Date] October 3, 2018 [Meeting] The Fiber Society's Fall 2018 Technical Meeting and Conference [Date] October 29, 2018 [Publisher] Japan Society for the Promotion of Science Textiles・120th Committee on Functional Polymer Processing [Publication name] ISDF2018 Abstracts [Date of issue] November 11, 2018 [Meeting name] ISDF2018 [Date] November 12, 2018 [Publisher name] General The Japan Society of Plastics Processing [Publication name] The 26th Autumn Meeting of the Society of Plastics Processing [Publication date] November 19, 2018 [Meeting name] The 26th Autumn Meeting of the Society of Plastics Processing [Date] November 26th and 27th, 2018 [Published by] Tokyo Institute of Technology, School of Materials Science and Technology, Materials Course [Publication] Tokyo Institute of Technology, School of Materials Science and Technology, Materials Course (Organic Materials) Master's Thesis Abstracts [ Publication date] February 5, 2019 [Meeting name] Tokyo Institute of Technology, School of Materials Science and Engineering, Materials course, Master's thesis presentation (organic materials) [Date] February 12, 2019

TECHNICAL FIELD The present invention relates to a method for producing biodegradable fibers using polyhydroxyalkanoate (hereinafter sometimes abbreviated as "PHA") as a raw material.

In recent years, there have been concerns that plastic waste is causing a great burden on the global environment, such as the impact on ecosystems, the generation of toxic gases when burned, and global warming due to the large amount of heat generated by combustion. The development of biodegradable plastics is gaining momentum as plastics that can solve the above problems.

In particular, when biodegradable plastics derived from plants are burned, the carbon dioxide released is originally in the air, and it is said that the amount of carbon dioxide in the atmosphere does not increase. This is called carbon neutrality, and is emphasized under the Paris Agreement, which imposes carbon dioxide reduction targets, and the active use of plant-derived biodegradable plastics is desired.

Recently, from the viewpoint of biodegradability and carbon neutrality, aliphatic polyesters have attracted attention as plant-derived biodegradable plastics. Among them, PHA, especially poly(3-hydroxybutyrate) homopolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer, poly(3-hydroxybutyrate-co-3 -hydroxyhexanoate) copolymer (hereinafter sometimes abbreviated as PHBH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer and the like are attracting attention.

These PHAs, especially PHBHs, are slow to crystallize and are difficult to form into fibers by ordinary melt spinning. Therefore, various attempts have been made to produce fibers having mechanical properties that satisfy market demands.

Patent Document 1 discloses that a polyester fiber having high tensile strength is produced by melt-spinning PHBH at a take-up speed of 1500 m/min or higher.

Further, in Patent Document 2, by blending a specific crystal nucleating agent and a specific lubricant with PHA to form a polyester fiber, the spinnability and productivity at a high take-up speed are improved, and the tensile strength of the fiber is improved. It is disclosed to increase

Although it is not intended for high strength, in Patent Document 3, after PHA such as PHBH is melt extruded, the fiber is rapidly cooled to 0 ° C., held at that temperature, and then continuously drawn. , disclose the production of PHA fibers with a stable fiber shape in the length direction.

On the other hand, in Patent Document 4, regarding the production of polyester fibers having polyethylene terephthalate as a main component instead of PHA, the polyester is discharged from a spinneret, passed through a heating device at 180°C, and then cooled at 40°C. It is disclosed to produce high strength polyester fibers by passing through.

WO2015/029316 WO2017/122679 JP 2018-159142 A JP 2006-328550 A

According to the methods described in Patent Documents 1 and 2, high-strength PHA fibers can be obtained, but high-speed spinning is required. Spinning at high speeds, however, carries the risk of yarn breakage during spinning and requires the use of special and expensive take-up equipment.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a production method capable of providing a polyhydroxyalkanoate fiber having high tensile strength without spinning at high speed.

The present inventors have made intensive studies to solve the above problems, and in the melt spinning of PHA, by passing a liquid phase at a specific temperature while winding the fiber discharged from the spinneret on a take-up roll, the low speed The present inventors have found that a polyhydroxyalkanoate fiber with high tensile strength can be produced by spinning the above, resulting in the present invention.

That is, the present invention comprises a step of melting a resin material containing a polyhydroxyalkanoate and discharging it from a spinneret in the form of fibers, wherein the fibers made of the discharged resin material contain a water-soluble liquid other than water. The present invention relates to a method for producing biodegradable fibers, comprising a step of passing a liquid phase at a temperature of 20 to 60° C., and a step of winding the fibers that have passed through the liquid phase onto a roll.
Preferably, the water-soluble liquid contains at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, alkylene glycol, and alcohol. More preferably, the water-soluble liquid contains polyethylene glycol, and the polyethylene glycol has 2 to 4 oxyethylene chains.
Preferably, the depth of the liquid phase is 2-30 cm.
Preferably, the winding speed on the roll is 50 to 2000 m/min.
Preferably, the resin material contains at least one lubricant selected from the group consisting of behenic acid amide, stearic acid amide, erucic acid amide, and oleic acid amide.
Preferably, said polyhydroxyalkanoate is poly(3-hydroxybutyric acid), poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid), poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid), and poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid). More preferably, said polyhydroxyalkanoate comprises poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid). More preferably, the monomer ratio of 3-hydroxybutyric acid in the poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid) is 85.0 mol % or more and 99.5 mol % or less.

According to the present invention, polyhydroxyalkanoate fibers with high tensile strength can be produced without spinning at high speed.

Conceptual diagram showing one embodiment of the manufacturing method of the present invention

The present invention will be described in detail below.
TECHNICAL FIELD The present invention relates to a method for producing biodegradable fibers mainly composed of polyhydroxyalkanoate (PHA) (hereinafter also referred to as "PHA fibers"). The PHA used in the present invention _is a polyester having a _{hydroxyalkanoic} acid as a _monomer. and n is an integer of 1 or more and 15 or less.).

Specific examples of PHA in the present invention include PHB [poly(3-hydroxybutyrate) or poly-3-hydroxybutyric acid], PHBH [poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)], , or poly (3-hydroxybutyric acid-co-3-hydroxyhexanoic acid)], PHBV [poly (3-hydroxybutyrate-co-3-hydroxyvalerate), or poly (3-hydroxybutyric acid-co-3- hydroxyvaleric acid)], P3HB4HB [poly(3-hydroxybutyrate-co-4-hydroxybutyrate), or poly(3-hydroxybutyrate-co-4-hydroxybutyrate)], poly(3-hydroxybutyrate- co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), and the like. Among these, PHB, PHBH, PHBV, and P3HB4HB can be mentioned as those that are easy to produce industrially. In the present invention, it is preferable to use PHBH as the PHA from the viewpoint of strength of the obtained PHA fiber.

From the viewpoint of flexibility and strength, PHA preferably contains a 3-hydroxybutyrate unit. Among them, from the viewpoint of the balance between flexibility and strength, it is more preferable that the average composition ratio of 3-hydroxybutyrate units contained in PHA is 85.0 mol% to 99.5 mol%, and 85.0 mol. % to 97.0 mol % are more preferred. If the average compositional ratio of 3-hydroxybutyrate units is less than 85.0 mol %, the rigidity tends to be insufficient, and if it exceeds 99.5 mol %, the flexibility tends to be insufficient.

In the present invention, PHA may be used singly or in combination of two or more. When a copolymer such as PHBH is used as the PHA, two or more copolymers having different average composition ratios of monomer units such as 3-hydroxybutyrate units may be mixed and used.

The molecular weight of the PHA used in the present invention is not particularly limited as long as the final PHA fiber exhibits substantially sufficient physical properties for the intended use. However, when the molecular weight is low, the strength of the PHA fiber tends to decrease, and when the molecular weight is high, the workability decreases and fiberization may become difficult. From this point of view, the weight average molecular weight range of the PHA used in the present invention is preferably 50,000 to 3,000,000, more preferably 100,000 to 1,500,000. In addition, the weight average molecular weight here refers to the one measured from the polystyrene equivalent molecular weight distribution using gel permeation chromatography (GPC) using a chloroform eluent. As the column in the GPC, a column suitable for measuring the molecular weight may be used.

The PHA used in the present invention preferably has a melt flow rate of 0.1 to 100, more preferably 1 to 50, even more preferably 10 to 40, measured at 160° C. under a load of 5 kg. If the melt flow rate is too low, the fluidity of the molten resin will be insufficient, and if it is too high, the fluidity will be too high, making it difficult to pick up the fibers in either case.

Although the glass transition temperature of the PHA used in the present invention is not particularly limited, it is preferably -30 to 10°C. In the present invention, the glass transition temperature is measured by differential scanning calorimetry at a heating rate of 10° C./min.

The method for producing PHA is not particularly limited, but examples thereof include a method of producing PHA using a microorganism capable of producing PHA. Although such microorganisms are not particularly limited, examples of PHB-producing bacteria include Bacillus megaterium discovered in 1925, and Cupriavidus necator (former classification: Alcaligenes eutrophus, Ralstonia eutrophus). eutropha (Ralstonia eutropha), Alcaligenes latus (Alcaligenes latus), etc. Examples of copolymer-producing bacteria of 3-hydroxybutyrate and other hydroxyalkanoates include Aeromonas, which is a PHBV- and PHBH-producing bacterium. Aeromonas caviae, P3HB4HB-producing Alcaligenes eutrophus, etc. In particular, PHBH-producing bacteria include Alcaligenes into which PHA synthase group genes have been introduced in order to increase PHBH productivity. - Eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) (T. Fukui, Y. Doi, J. Bacteriol., 179, p4821-4830 (1997)).

PHA can be produced by culturing these microorganisms under appropriate conditions to accumulate PHA in the cells and recovering the PHA. Culture conditions, including the type of substrate, can be optimized according to the microorganism used. In addition to the microorganisms listed above, PHA can also be produced by culturing genetically modified microorganisms into which various PHA synthesis-related genes have been introduced according to the PHA to be produced.

In producing the biodegradable fiber in the present invention, PHA alone may be melt-extruded, or PHA may be melt-extruded with polymer components other than PHA and various additives. The amount of these components added is not particularly limited as long as it does not impair the properties of the PHA fiber.

As the polymer component other than PHA, a biodegradable polymer component is preferable. Examples include, but are not limited to, glycolic acid, unmodified starch, modified starch, cellulose acetate, chitosan, and the like. These may be used alone or in combination of two or more. When these other polymer components are blended, the blending amount is 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, more preferably 1 to 10 parts by weight per 100 parts by weight of PHA. It may be about parts by weight.

Additives that can be used in the present invention are not particularly limited. A nucleating agent or the like for

The lubricant is not particularly limited, but examples include fatty acid amides such as behenic acid amide, stearic acid amide, erucic acid amide and oleic acid amide, alkylene fatty acid amides such as methylenebisstearic acid amide and ethylenebisstearic acid amide, and polyethylene. Wax, oxidized polyester wax, glycerin monostearate, glycerin monobehenate, glycerin monolaurate and other glycerin monofatty acid esters, organic acid monoglycerides such as succinic acid saturated fatty acid monoglyceride, sorbitan behenate, sorbitan stearate, sorbitan laurate Sorbitan fatty acid esters such as diglycerin stearate, diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate, polyglycerin fatty acid esters such as decaglycerin laurate, higher alcohol fatty acids such as stearyl stearate and esters. These may be used alone or in combination of two or more. Among the above lubricants, fatty acid amides and polyglycerin fatty acid esters are preferred, and behenic acid amides, stearic acid amides, erucic acid amides, and oleic acid amides are more preferred in terms of availability and high effectiveness.

Although the above plasticizer is not particularly limited, examples include modified glycerin compounds such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate, and adipins such as diethylhexyl adipate, dioctyl adipate, and diisononyl adipate. acid ester compounds, polyether ester compounds such as polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, polyethylene glycol diisostearate, benzoic acid ester compounds, epoxidized soybean oil, epoxidized fatty acid 2-ethylhexyl, sebacic acid system monoesters, and the like. These may be used alone or in combination of two or more. Among the above plasticizers, modified glycerin-based compounds and polyether ester-based compounds are preferred in terms of availability and high effectiveness.

The above inorganic fillers are not particularly limited, but examples include titanium oxide, calcium carbonate, talc, clay, synthetic silicon, carbon black, barium sulfate, mica, glass fibers, whiskers, carbon fibers, magnesium carbonate, glass powder, and metals. Powder, kaolin, graphite, molybdenum disulfide, zinc oxide, etc. can be mentioned, and one or more of these can be contained. Among the above inorganic fillers, titanium oxide and calcium carbonate are preferable in terms of high effect.

The above-mentioned nucleating agent is not particularly limited, but examples include inorganic substances such as boron nitride, titanium oxide, talc, layered silicate, calcium carbonate, sodium chloride, and metal phosphate, erythritol, galactitol, mannitol, and arabitol. sugar alcohol compounds derived from natural products, pentaerythritol, polyvinyl alcohol, chitin, chitosan, polyethylene oxide, aliphatic carboxylic acid amides, aliphatic carboxylates, aliphatic alcohols, aliphatic carboxylic acid esters, dimethyl adipate, dibutyl adipate, Dicarboxylic acid derivatives such as diisodecyl adipate and dibutyl sebacate, cyclic compounds having functional groups selected from C=O and NH, S and O such as indigo, quinacridone, and quinacridone magenta in the molecule, bisbenzylidene sorbitol and bis( sorbitol derivatives such as p-methylbenzylidene) sorbitol, compounds containing nitrogen-containing heteroaromatic nuclei such as pyridine, triazine and imidazole, phosphate ester compounds, bisamides of higher fatty acids, metal salts of higher fatty acids, branched poly Lactic acid, low-molecular-weight poly-3-hydroxybutyric acid and the like can be mentioned. These may be used alone or in combination of two or more. Among the above nucleating agents, pentaerythritol, sugar alcohol compounds, polyvinyl alcohol, chitin, and chitosan are preferable, and pentaerythritol is particularly preferable, from the viewpoint of improving the crystallization speed and mixing with biodegradable fibers. These may be used alone or in combination of two or more.

The method for producing biodegradable fibers of the present invention relates to a method for producing fibers by continuous melt spinning, and includes at least a melt extrusion step (first step), a liquid passing step (second step), and a winding step (second step). three steps) in this order, thereby continuously producing a biodegradable fiber from a PHA-containing resin material.

First, in the first step, an extruder is used to melt a resin material containing polyhydroxyalkanoate, and the fiber is extruded from a spinneret connected to the tip of the extruder to obtain a molten polyester fiber (hereinafter referred to as , also called molten filaments). As the extruder to be used, a general single-screw extruder or twin-screw extruder commonly used in the melt spinning method can be used. The cylinder temperature and die exit temperature of the extruder may be adjusted according to the molecular weight and monomer composition of the PHA to be used so that the melt viscosity of the PHA is appropriately maintained. The melt viscosity of the molten filament extruded from the extruder is preferably within a range in which tension suitable for fiber winding is maintained and cooling and crystallization and solidification are possible.

The temperature during melt extrusion in the first step may be adjusted from the viewpoint of the melt viscosity of the melt filament, and is not particularly limited, but is preferably 145°C to 200°C, more preferably 150°C to 190°C. is. Here, the temperature during melt extrusion includes both the extruder cylinder temperature and the die exit temperature. If the temperature during melt extrusion is lower than 145°C, spinning may become unstable due to the presence of unmelted components in the molten filaments. On the other hand, when the temperature is higher than 200°C, the resin tends to be thermally decomposed, so the spinning becomes unstable and the physical properties of the resulting fiber may be impaired.

The spinneret used to extrude the molten resin material into fibrous form may be selected with an appropriate opening area in consideration of the diameter of the fiber to be produced. In addition, depending on the shape of the spinneret opening, fibers having various cross-sectional shapes can be obtained. The cross-sectional shape of the opening is not particularly limited, but in addition to a general round shape, a mouthpiece having a cross-sectional shape such as oval, Y-shaped, X-shaped, H-shaped, multi-lobed, etc. can be used. .

In the second step, the fibers discharged from the spinneret as described above are passed through a liquid phase. Passing the liquid phase through can impart stress to the fibers, thereby orienting the resin in the fibers and, as a result, improving the tensile strength of the fibers.

In the present invention, a water-soluble liquid other than water is used as the liquid used for the liquid phase. By using a water-soluble liquid, the liquid can be easily removed from the fibers by washing the fibers after passing through the liquid phase.

Any liquid can be used as the water-soluble liquid, and for example, polyethylene glycol, polypropylene glycol, alkylene glycol, or alcohol can be preferably used. Examples of alkylene glycol include ethylene glycol and propylene glycol. Alcohols include methanol, ethanol, n-propanol, iso-propanol and the like. As the water-soluble liquid, only one type may be used, or two or more types may be mixed and used.

As the water-soluble liquid, polyethylene glycol or polypropylene glycol is preferable, and polyethylene glycol is more preferable, because it is excellent in the effect of improving the tensile strength of the fiber. At this time, it is particularly preferable that the polyethylene glycol has 2 to 4 oxyethylene units.

The liquid phase preferably has a certain degree of viscosity from the viewpoint of imparting stress to the fibers as the liquid phase passes through. Specifically, the preferred viscosity of the liquid phase is in the range of 10 to 60 mPa·s, more preferably in the range of 15 to 50 mPa·s, and even more preferably in the range of 20 to 40 mPa·s. The viscosity of the water-soluble liquid is temperature dependent and changes with temperature. For example, when polyethylene glycol having 2 to 4 oxyethylene unit chains is used as the water-soluble liquid, the temperature may be set so that the viscosity of the polyethylene glycol falls within the above viscosity range. preferable.

Specifically, the viscosity of polyethylene glycol having three oxyethylene chains is 10-15 mPa·s at 20°C, 21-27 mPa·s at 40°C, and 52-58 mPa·s at 60°C. In this case, at temperatures below 20° C., the viscosity of the liquid phase becomes too high, and at temperatures above 60° C., the viscosity of the liquid phase becomes too low. If the viscosity of the liquid phase is too high, too much stress will be applied to the fiber during spinning, causing yarn breakage. On the other hand, if the viscosity of the liquid phase is too low, stress cannot be applied to the fibers, resulting in insufficient orientation of the fibers.

It is desirable to adjust the viscosity of the liquid phase with temperature so that the viscosity of the liquid phase is within the above viscosity range. In addition, increasing the number of oxyethylene chains possessed by polyethylene glycol also increases the viscosity, so it is also effective to change the type of polyethylene glycol to be used so as to obtain an appropriate viscosity. Moreover, in order to adjust the viscosity to an appropriate level, polyethylene glycol may be mixed with propylene glycol, polypropylene glycol, water-soluble alcohol, or the like to form a liquid phase.

The temperature of the liquid phase is preferably in the range of 20 to 60°C, although it depends on the type of water-soluble liquid to be used and its viscosity characteristics. Within this temperature range, it is preferred that the viscosity of the liquid phase be within the range described in the preceding paragraph. During melt spinning, the temperature of the liquid phase is preferably adjusted to be maintained within this range. If the temperature of the liquid phase is less than 20°C or more than 60°C, it is out of the optimum temperature range for crystallization, and the tensile strength of the PHA-based fiber cannot be sufficiently improved. The lower limit of the temperature of the liquid phase is preferably 25°C, more preferably 30°C. Moreover, the upper limit is more preferably 50°C, still more preferably 45°C, and particularly preferably 40°C.

Patent Document 4 describes that in the production of polyester fibers containing polyethylene terephthalate as a main component, fibers discharged from a spinneret are passed through a heating device at 180°C and then passed through a cooling device at 40°C. However, in the present invention, it is not necessary to pass through a heating device at 180°C, and the fibers discharged from the spinneret may be directly passed through a liquid phase at 20 to 60°C.

The depth of the liquid phase is not particularly limited, but if it is too shallow, the effects of the liquid phase cannot be sufficiently obtained. Also, even if the depth is too deep, a corresponding effect cannot be obtained, and the size of the liquid tank is increased, which is not preferable. From this point of view, 2 to 30 cm is preferable. The lower limit of the depth is more preferably 5 cm, still more preferably 10 cm. The upper limit of the depth is more preferably 25 cm, still more preferably 20 cm.

The third step is to wind the fibers on a roll after passing through the liquid phase. A normal take-up roll may be used as the roll. The take-up roll is arranged outside the liquid phase. It is also possible to place a take-up roll between the liquid phase and the take-up roll. By installing the take-up roll, the load on the take-up roll is reduced and the winding is stabilized. It is also possible to install a water tank for removing the water-soluble liquid adhering to the fibers between the take-up roll and the winding roll, and to install a drying process after washing the fibers.

The speed at which the fiber is wound onto the roll can be appropriately set by those skilled in the art, but in the present invention, it is preferably 50 to 2000 m/min from the viewpoint of improving the tensile strength of the fiber. In the present invention, if the winding speed exceeds 2000 m/min, the tensile strength of the fiber may not improve. The lower limit of the winding speed is preferably 100 m/min, more preferably 200 m/min, still more preferably 300 m/min, particularly preferably 400 m/min, most preferably 500 m/min. The upper limit of the winding speed is preferably 1500 m/min, more preferably 1400 m/min, still more preferably 1300 m/min, even more preferably 1200 m/min, particularly preferably 1100 m/min, and most preferably 1000 m/min. .

Next, the present invention will be specifically described with reference to the drawings.
FIG. 1 is a conceptual diagram showing one embodiment of the present invention. In this embodiment, fibers 3 are extruded from a spinneret 2 connected to the tip of an extruder 1 . The discharged fibers 3 travel linearly and are wound up by a winding roll 4 arranged vertically downward. Between the spinneret 2 and the take-up roll 4 the fibers 3 pass through a liquid phase 6 in a bath 5 . The temperature of the liquid phase 6 is kept at 30° C., for example. The bottom surface of the liquid tank 5 holding the liquid phase 6 is provided with a hole 7 having a diameter that allows the fibers 3 to pass through. The fibers 3 enter the liquid phase 6 from the surface of the liquid phase 6 , exit the liquid phase 6 through the holes, and are wound up on the winding roll 4 .

FIG. 1 shows the case where the fiber 3 runs straight, but the present invention is not limited to this, and the fiber 3 moves from the spinneret 2 to the liquid phase 6 or from the liquid phase 6 to the take-up roll 4. Another roll (not shown) may be provided in between to change the direction of the travel path of the fibers 3 . In addition, by providing another roll (not shown) in the liquid phase 6 and reversing the traveling path of the fibers 3 in the liquid phase 6, the fibers that have entered the liquid phase from the liquid surface of the liquid phase 6 are Similarly, from the liquid surface of the liquid phase 6, it may be made to go out of the liquid phase. In this case, it is not necessary to provide the holes 7 in the bottom surface of the liquid tank 5 .

According to the present invention, biodegradable fibers can be continuously produced by melt spinning, and the obtained biodegradable fibers are mainly composed of PHA and have good tensile strength. can. In addition, by selecting the conditions for melt spinning within the range described above, it is possible to achieve a high level of tensile strength that could not be achieved by the production methods described in Patent Documents 1 and 2, for example, using conventional high-speed spinning. is also possible.

Further, in the present invention, a drawing step after melt spinning may be performed as described in Patent Document 3, but the effects of the present invention can be achieved without performing the drawing step. Since PHA has a low glass transition temperature of around 0° C. and crystallizes at room temperature, it is usually difficult to carry out a drawing process after spinning. Therefore, according to the present invention, there is a great advantage that a high-strength PHA fiber can be obtained without performing a drawing step.

Biodegradable fibers obtained by the present invention, like known fibers, can be used in agriculture, fisheries, forestry, clothing, non-clothing textile products (for example, curtains, carpets, bags, etc.), sanitary products, gardening, automobile parts, building materials, medical products, etc. , food industry, and other fields.

EXAMPLES The present invention will be specifically described below with reference to examples, but the technical scope of the present invention is not limited by these examples.

<Production Example 1> Production of PHBH KNK-005 strain (see US Pat. No. 7,384,766) was used for culture production.

The composition of the seed medium is 1 w/v% Meat-extract, 1 w/v% Bacto-Tryptone, 0.2 w/v% Yeast-extract, 0.9 w/v% Na ₂ HPO ₄ ·12H ₂ O, 0.15 w. /v% KH ₂ PO ₄ , (pH 6.8).

The composition of the pre-culture medium is 1.1 w/v% _{Na2HPO4-12H2O} , 0.19 _{w /} v% _KH2PO4 , _1.29 w/v% ( _NH4 ) _2SO4 , _0.1 w/v% v% _MgSO4.7H2O , 0.5 v/v% trace metal _salt solution (1.6 _w / _v % _FeCl3.6H2O , 1 w/v% _CaCl2.2H2O in 0.1N hydrochloric acid, 0 .02 w/v% CoCl ₂ .6H ₂ O, 0.016 w/v% CuSO ₄ .5H ₂ O, and 0.012 w/v% NiCl ₂ .6H ₂ O dissolved therein). As a carbon source, palm oil was added all at once at a concentration of 10 g/L.

_The composition of _the production medium is 0.385 w/v% _{Na2HPO4-12H2O} , 0.067 w/v% _KH2PO4 , 0.291 _w /v% ( _NH4 ) _2SO4 , _0.1 w/v. % _MgSO4.7H2O , 0.5 v/v % trace metal salt solution (1.6 _{w /} v % _FeCl3.6H2O , 1 w _/ v % _CaCl2.2H2O , 0.1 N hydrochloric acid in 02 w/v% CoCl ₂ .6H ₂ O, 0.016 w/v% CuSO ₄ .5H ₂ O, 0.012 w/v% NiCl ₂ .6H ₂ O.), 0.05 w/v% BIOSPUREX200K (Antifoaming agent: Cognis Japan Co., Ltd.).

First, the KNK-005 strain glycerol stock (50 μl) was inoculated into a seed medium (10 ml) and cultured for 24 hours for seed culture. Next, 1.0 v/v % of the seed culture was inoculated into a 3 L jar fermenter (MDL-300 manufactured by Marubishi Bioengineering Co., Ltd.) containing 1.8 L of preculture medium. The operating conditions were culture temperature of 33° C., agitation rate of 500 rpm, aeration rate of 1.8 L/min, and pH was controlled between 6.7 and 6.8 for 28 hours of culture for pre-culture. A 14% ammonium hydroxide aqueous solution was used for pH control.

Next, 1.0 v/v % of the preculture was inoculated into a 10 L jar fermenter (MDS-1000 manufactured by Marubishi Bioengineering Co., Ltd.) containing 6 L of production medium. Operating conditions were culture temperature of 28° C., stirring speed of 400 rpm, aeration rate of 6.0 L/min, and pH was controlled between 6.7 and 6.8. A 14% ammonium hydroxide aqueous solution was used for pH control. Palm oil was used as the carbon source. Cultivation was carried out for 64 hours. After completion of the cultivation, the cells were collected by centrifugation, washed with methanol, freeze-dried, and the dry cell weight was measured.

100 ml of chloroform was added to 1 g of the obtained dry cells, and the mixture was stirred at room temperature for a whole day and night to extract PHBH in the cells. After removing the bacterial cell residue by filtration, it was concentrated with an evaporator until the total volume reached 30 ml, and then 90 ml of hexane was gradually added and allowed to stand for 1 hour while slowly stirring. After separating the precipitated PHBH by filtration, it was vacuum-dried at 50° C. for 3 hours to obtain PHBH.

The 3HH composition of the obtained PHBH was measured by gas chromatography as follows. 2 ml of a sulfuric acid-methanol mixture (15:85) and 2 ml of chloroform were added to 20 mg of dry PHBH, and the mixture was sealed and heated at 100° C. for 140 minutes to obtain a methyl ester of a PHBH decomposition product. After cooling, 1.5 g of sodium bicarbonate was added little by little to neutralize the mixture, and the mixture was allowed to stand until the generation of carbon dioxide ceased. After adding 4 ml of diisopropyl ether and mixing well, the mixture was centrifuged and the monomer unit composition of the polyester decomposed product in the supernatant was analyzed by capillary gas chromatography. Shimadzu GC-17A was used as the gas chromatograph, and NEUTRA BOND-1 manufactured by GL Sciences was used as the capillary column (column length: 25 m, column inner diameter: 0.25 mm, liquid film thickness: 0.4 μm). He was used as a carrier gas, the column inlet pressure was set to 100 kPa, and 1 μL of sample was injected. The temperature was raised from the initial temperature of 100° C. to 200° C. at a rate of 8° C./min, and further from 200° C. to 290° C. at a rate of 30° C./min. As a result of analysis under the above conditions, the PHBH was found to have a monomer ratio of 3-hydroxyhexanoate (3HH) of 5.4 mol %. The weight average molecular weight Mw measured by GPC was 350,000, the melting point was 141°C, and the glass transition temperature was 0°C.

(Measurement of weight average molecular weight)
The weight average molecular weight is determined by gel permeation chromatography ("Shodex GPC-101" manufactured by Showa Denko Co., Ltd.), using polystyrene gel ("Shodex K-804" manufactured by Showa Denko Co., Ltd.) as a column, using chloroform as a mobile phase, polystyrene. It was obtained as a molecular weight when converted. At this time, a calibration curve was prepared using polystyrene having weight average molecular weights of 31,400, 197,000, 668,000 and 1,920,000.

<Examples 1 to 9, and Comparative Examples 3 to 5>
PHBH (100 parts by weight) obtained in Production Example 1 was dry-blended with 0.5 parts by weight of behenic acid amide, and extruded at 130 to 160°C using a twin-screw extruder (TEM26SS) manufactured by Toshiba Machine Co., Ltd. It was melt-kneaded and pelletized. Then, the pellets are melted in a single-screw extruder with a screw diameter of 20 mm, the flow rate is adjusted with a gear pump, and the melt spinning temperature is 180° C., and the amount of resin discharged from a spinning die having one spinning hole with a diameter of 1 mm5. Continuous melt spinning was performed by extruding at 0 g/min and taking the fiber with a take-off roll at 25° C. at the take-up speed indicated in the table.

After fiber take-up stabilized, a constant temperature bath was placed between the spinning die and the take-up roll while continuous melt spinning was continued. A circular hole was provided in the bottom of the constant temperature bath, and the constant temperature bath was installed so that running fibers could pass through the hole. After installation, the constant temperature bath was filled with a liquid (polyethylene glycol: degree of polymerization = 4, viscosity: listed in Table 1) set at the temperature listed in the table to the liquid bath depth listed in the table. A liquid at a set temperature was circulated in the constant temperature bath from a separately installed constant temperature bath using a liquid feed pump, and the temperature of the liquid and the depth of the liquid bath were maintained at the values shown in the table. In this way, the fiber discharged from the spinning die is passed through a liquid phase at a specific temperature while being wound on the take-up roll. In this state, continuous melt spinning was continued at the take-up speed shown in the table to obtain fibers. The obtained fibers were washed with pure water, air-dried at room temperature for 1 day, and evaluated as follows.

<Comparative Examples 1 and 2, and Reference Examples 1 and 2>
PHBH (100 parts by weight) obtained in Production Example 1 was dry-blended with 0.5 parts by weight of behenic acid amide, and extruded at 130 to 160°C using a twin-screw extruder (TEM26SS) manufactured by Toshiba Machine Co., Ltd. It was melt-kneaded and pelletized. Then, the pellets are melted in a single-screw extruder with a screw diameter of 20 mm, the flow rate is adjusted with a gear pump, and the melt spinning temperature is 180° C., and the amount of resin discharged from a spinning die having one spinning hole with a diameter of 1 mm5. Fibers were obtained by continuous melt spinning by extruding at 0 g/min and taking off the fibers with take-off rolls at 25° C. at the take-up speeds listed in the table. The obtained fibers were washed with pure water and air-dried for 1 day in order to match the conditions with the samples using the constant temperature bath.

The take-up speed, liquid bath depth, and liquid temperature are shown in the table.

The obtained polyester fibers were evaluated as follows.

(tensile strength)
The tensile strength of the obtained fiber was measured under the following conditions using a tensile tester Autograph AG-I manufactured by Shimadzu Corporation. That is, the initial length of the sample was 20 mm, and the measurement was performed at a speed of 20 mm/min. The results are shown in the table.

(Diffraction intensity from specific crystal)
An X-ray diffractometer (RINT) manufactured by Rigaku was used to measure the diffraction intensity of the obtained fiber, and CuKα rays generated at a filament voltage of 45 kV and a filament current of 60 mA were used through a nickel filter. A two-dimensional diffraction pattern was measured using a Rigaku Mercury CCD, and the diffraction intensity distribution was calculated from the intensity in the equatorial direction. The sample-to-camera distance was 48.92 mm, and the diffraction angle was calibrated using the (111) reflection of a silicon crystal. In the diffraction angle range of 15° to 21° in the obtained diffraction intensity distribution, the straight line drawn from 15° to 21° was regarded as the intensity based on amorphous scattering, and that amount was subtracted from the diffraction intensity. After that, the maximum value between 15 ° and 18 ° is the crystallinity (α): the diffraction intensity from the α-type crystal, and the maximum value between 18 ° and 21 ° is the crystallinity (β): β. Diffraction intensity from the type crystal. The results are shown in the table.

From the table, in Examples 1 to 9 in which the fibers discharged from the spinning die were passed through a liquid phase set in the range of 20 to 60 ° C., the tensile strength equivalent to that of Reference Examples 1 and 2 in which high speed spinning was performed, or It can be seen that fibers with high tensile strength exceeding those of Reference Examples 1 and 2 were obtained.

On the other hand, it can be seen that in Comparative Examples 1 and 2 in which the same take-up speed as in Examples 1 to 9 was employed, but the fibers after ejection were not passed through the liquid phase, the tensile strength of the obtained fibers was low.

Further, in Comparative Examples 3 to 5, in which the same take-up speed as in Examples 1 to 9 was used and the fiber after ejection was passed through the liquid phase, the temperature of the liquid phase was as high as 80° C. or higher. It can be seen that the tensile strength was low.

REFERENCE SIGNS LIST 1 extruder 2 spinneret 3 fiber 4 take-up roll 5 liquid tank 6 liquid phase 7 holes

Claims (6)

Formula (1): represented by [-CHR-CH ₂ -CO-O-] (wherein R is an alkyl group represented by C _n H _2n+1 , and n is an integer of 1 or more and 15 or less) A step of melting a resin material containing polyhydroxyalkanoate, which is an aliphatic polyester containing repeating units , and discharging it into a fibrous form from a spinneret;
A liquid phase containing a water-soluble liquid containing at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, alkylene glycol, and alcohol and having a temperature of 20 to 60 ° C. and winding the fibers that have passed through the liquid phase onto a roll ,
the liquid phase has a depth of 2 to 30 cm;
The speed of winding on the roll is 50 to 2000 m / min,
A method for producing a biodegradable fiber, wherein the amount of polymer components other than the polyhydroxyalkanoate in the resin material is 50 parts by weight or less per 100 parts by weight of the polyhydroxyalkanoate. 2. The method for producing a biodegradable fiber according to claim 1 , wherein the water-soluble liquid contains polyethylene glycol, and the polyethylene glycol has 2 to 4 oxyethylene units. The biodegradable fiber according to claim 1 or 2 , wherein the resin material contains at least one lubricant selected from the group consisting of behenic acid amide, stearic acid amide, erucic acid amide, and oleic acid amide. Production method. The polyhydroxyalkanoates include poly(3-hydroxybutyric acid), poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid), poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid), and poly( 4. The method for producing a biodegradable fiber according to any one of claims 1 to 3 , comprising at least one selected from the group consisting of 3-hydroxybutyric acid-co-4-hydroxybutyric acid. The method for producing biodegradable fibers according to claim 4 , wherein the polyhydroxyalkanoate comprises poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid). The biodegradable fiber according to claim 5 , wherein the poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid) has a monomer ratio of 3-hydroxybutyric acid of 85.0 mol% or more and 99.5 mol% or less. manufacturing method.

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