JP2021008605A - Modified hydroxycarboxylic acid polymer - Google Patents

Abstract

To provide a modified hydroxycarboxylic acid polymer that can form a fine fiber, and when formed into the fine fiber, exhibits excellent hydrolysis resistance, and a resin composition containing the modified hydroxycarboxylic acid polymer and a method for producing the same, and a fiber containing the same.SOLUTION: A modified hydroxycarboxylic acid polymer includes a terminal group which is an oxyhydrocarbon group having 6-30 carbon atoms.SELECTED DRAWING: None

Description

The present invention relates to a modified hydroxycarboxylic acid polymer, a resin composition containing the modified hydroxycarboxylic acid polymer, a method for producing the same, and a fiber containing these.

With the aggravation of environmental problems such as the treatment of plastic waste, applied research on biodegradable resins such as hydroxycarboxylic acid polymers is being actively conducted.

Fine-diameter fibers are used in various fields, and in recent years, further reduction in diameter of fibers and improvement of surface physical properties of fibers have been desired. Among them, the electric field spinning method has been developed and is attracting attention. This method is different from the conventional spinning method in that a potential difference is generated between the discharge port and the winding of the fiber, and this potential difference can be used to draw at high speed to obtain fine fibers having a diameter of submicron or less. Therefore, new application development is expected. Examples of electric field spinning include a method of spinning a resin solution in which a resin is dissolved in an appropriate solvent and a method of spinning a melt of the resin. In the former, since the fluidity of the resin solution can be adjusted by adjusting the amount of the solvent and the solvent type, fine fibers can be easily obtained, but the step of dissolving the resin in the solvent and the step of removing the solvent Is required. The latter has high productivity because the resin itself is melted, but it is necessary to suppress the molecular weight of the resin and secure the fluidity of the molten resin in order to miniaturize the fiber. In order to increase the fluidity of the molten resin, it is necessary to use a resin having a low molecular weight.

For example, Patent Document 1 discloses a method for reducing the molecular weight of a high molecular weight aliphatic polyester by alcoholesis. Further, Patent Document 2 discloses an ester-exchanged polylactic acid product that has been transesterified with diethylene glycol and natural oil.

Japanese Unexamined Patent Publication No. 5-1142 Special Table 2019-503428 Gazette

The hydroxycarboxylic acid polymer is excellent in biodegradability but inferior in hydrolysis resistance. The lower the molecular weight, the more pronounced the tendency. Therefore, fine fibers using a hydroxycarboxylic acid polymer as a molten resin are likely to be hydrolyzed in a wet state, and their use is limited to use in a dry state or the like. Therefore, hydroxycarboxylic acid weight has high stability even when used in products that are used wet with water, such as containers used in wet places such as washrooms, kitchens, and bathrooms, or cloths. Coalescence is required. However, Patent Document 1 only discloses a method for reducing the molecular weight of poly-3-hydroxybutyrate (P3HB) by alkolisis in which poly-3-hydroxybutyrate (P3HB) is reacted with propanol, and the improvement of hydrolysis resistance of the aliphatic polyester Is not mentioned at all. Further, Patent Document 2 merely discloses the glass transition temperature of the transesterified polylactic acid product transesterified with diethylene glycol and natural oil and the thermal stability around 200 ° C., and is hydrolyzable. There is no mention of improvement.

INDUSTRIAL APPLICABILITY According to the present invention, a modified hydroxycarboxylic acid polymer capable of obtaining fine fibers and having excellent hydrolysis resistance when made into fine fibers, a resin composition containing the modified hydroxycarboxylic acid polymer, and production thereof. With respect to methods and fibers containing them.

The present invention relates to the following [1] to [4].
[1] A modified hydroxycarboxylic acid polymer having an oxyhydrocarbon group having 6 to 30 carbon atoms as a terminal group.
[2] A resin composition containing the modified hydroxycarboxylic acid polymer according to [1].
[3] 0.01 part by mass or more and 5 parts by mass with respect to 100 parts by mass of the modified hydroxycarboxylic acid polymer and the modified hydroxycarboxylic acid polymer whose terminal group is an oxyhydrocarbon group having 6 or more and 30 or less carbon atoms. A resin composition containing the following lactones.
[4] A method for producing a resin composition containing a modified hydroxycarboxylic acid polymer, which comprises a step of alcoholic reaction of a hydroxycarboxylic acid polymer and an alcohol having 6 or more and 30 or less carbon atoms.
[5] A fiber containing the modified hydroxycarboxylic acid polymer according to [1] or the resin composition according to [2] or [3].

According to the present invention, a modified hydroxycarboxylic acid polymer capable of obtaining fine fibers and having excellent hydrolysis resistance when made into fine fibers, the modified hydroxycarboxylic acid polymer composition, and a method for producing the same. In addition, fibers containing these can be provided.

It is a schematic diagram of the molten electric field spinning apparatus used for electric field spinning in each Example and comparative example.

The present inventors have newly found that by introducing a specific oxyhydrocarbon group into the polyester chain terminal of a hydroxycarboxylic acid polymer, it is excellent in hydrolysis resistance even when it is made into fine fibers. Although this mechanism is not clear, it does not work as an acid because the carboxyl group terminal at the end of the polyester chain is blocked by an ester bond with alcohol, and it is hydrophobized with a hydrocarbon group having 6 to 30 carbon atoms. Therefore, it is presumed that the cause is that it is difficult for water to approach the ester bond formed at the end of the polyester chain.

[Modified hydroxycarboxylic acid polymer]
The modified hydroxycarboxylic acid polymer of the present invention is a modified hydroxycarboxylic acid polymer having an oxyhydrocarbon group having 6 to 30 carbon atoms as a terminal group. The terminal oxyhydrocarbon group is preferably bonded to a group obtained by removing a hydroxyl group from the carboxy group of the hydroxycarboxylic acid polymer.

The hydroxycarboxylic acid polymer according to the modified hydroxycarboxylic acid polymer of the present invention may be a homopolymer or a copolymer containing two or more kinds of monomer units. For example, homopolymers such as polylactic acid (PLA), polyglycolic acid, and poly-3-hydroxybutyric acid, and poly-3-hydroxybutyric acid-co-3-hydroxyvaleric acid, which is a poly-3-hydroxybutyric acid copolymer. (PHBV), poly-3-hydroxybutyric acid-co-4-hydroxybutyric acid and other copolymers can be mentioned. The homopolymer is preferably a polymer of an aliphatic hydroxycarboxylic acid, more preferably a polymer of hydroxyalkanoic acid, and further preferably carbon, from the viewpoints of improving biodegradability and moldability and ease of spinning. It is a polymer of number 2 to 6 of hydroxyalkanoic acid, more preferably polylactic acid, polyglycolic acid, polycaprolactone or polyhydroxybutyric acid, and further preferably polylactic acid, polyglycolic acid, polycaprolactone, poly-3- It is hydroxybutyrate or poly-4-hydroxybutyric acid, more preferably polylactic acid or polycaprolactone, and even more preferably polylactic acid. As the copolymer, one or 2 selected from the group consisting of a lactic acid unit, a caprolactone unit, a glycolic acid unit and a hydroxybutyric acid unit is preferable from the viewpoint of improving biodegradability and moldability and ease of spinning. A copolymer containing one or more species, more preferably one or more species, more preferably a lactic acid unit, selected from the group consisting of a lactic acid unit, a caprolactone unit, a 3-hydroxybutyric acid unit and a 4-hydroxybutyric acid unit.

The hydrocarbon group constituting the oxyhydrocarbon group is preferably a linear or branched saturated or unsaturated hydrocarbon group from the viewpoints of availability of raw materials, improvement of moldability, and ease of spinning. , More preferably a straight chain or branched alkyl group, and even more preferably a straight chain alkyl group. The number of carbon atoms of the oxyhydrocarbon group is 6 or more, preferably 8 or more, more preferably 12 or more, and the same, from the viewpoint of availability of raw materials, improvement of moldability, and ease of spinning. From the viewpoint of, it is 30 or less, preferably 22 or less, more preferably 18 or less, and further preferably 16 or less.

The mass ratio of the oxyhydrocarbon group to the hydroxycarboxylic acid unit (oxyhydrocarbon group / hydroxycarboxylic acid unit) in the modified hydroxycarboxylic acid polymer of the present invention is such that production stability is ensured, moldability is improved, and spinning is performed. From the viewpoint of ease of use, it is preferably 0.001 or more, more preferably 0.003 or more, further preferably 0.01 or more, still more preferably 0.02 or more, still more preferably 0.03 or more, and also. From the same viewpoint, it is preferably 0.4 or less, more preferably 0.1 or less, still more preferably 0.08 or less.

The weight average molecular weight of the modified hydroxycarboxylic acid polymer of the present invention is preferably 5,000 or more, more preferably 10,000 or more, still more preferably 15,000 or more, while being moldable, from the viewpoint of improving hydrolysis resistance. From the viewpoint of improvement and ease of spinning, it is preferably 100,000 or less, more preferably 90,000 or less, still more preferably 50,000 or less, still more preferably 40,000 or less. The weight average molecular weight is measured by the method described in Examples below.

[Resin composition containing a modified hydroxycarboxylic acid polymer]
The resin composition of the present invention contains the modified hydroxycarboxylic acid polymer of the present invention. The content of the modified hydroxycarboxylic acid polymer in the resin composition of the present invention is preferably 95% by mass or more, more preferably 98% by mass or more, still more preferably, from the viewpoint of improving hydrolysis resistance and moldability. Is 99% by mass or more, more preferably 99.5% by mass or more, and preferably 99.9% by mass or less from the viewpoint of improving productivity.

The resin composition of the present invention may contain a by-product of the production of the hydroxycarboxylic acid copolymer or a lactone as an unreacted raw material. Lactone is a general term for cyclic compounds containing -C (= O) -O- in the ring, and the lactone is an intramolecular ester cyclized by esterification between a carboxy group and a hydroxy group in the same molecule. Cyclic compounds having a lactic acid, lactide such as dilactide and glycolide, and the like can be mentioned. The content of the lactone in the resin composition of the present invention is preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, still more preferably, from the viewpoint of improving hydrolysis resistance. Is 0.5% by mass or less, and from the viewpoint of improving productivity, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.3% by mass or more. The lactone content is measured by the method described in Examples below.

The content of the lactone in the resin composition of the present invention is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, based on 100 parts by mass of the resin composition, from the viewpoint of improving hydrolysis resistance. It is more preferably 1 part by mass or less, further preferably 0.5 part by mass or less, and from the viewpoint of improving productivity, it is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, still more preferably. Is 0.3 parts by mass or more.

The content of the lactone in the resin composition of the present invention is preferably 5 parts by mass or less, more preferably 2 parts by mass, based on 100 parts by mass of the modified hydroxycarboxylic acid polymer from the viewpoint of improving hydrolysis resistance. Parts or less, more preferably 1 part by mass or less, still more preferably 0.5 part by mass or less, and from the viewpoint of improving productivity, preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more. More preferably, it is 0.3 parts by mass or more.

The resin composition of the present invention preferably contains an inorganic salt from the viewpoint of improving the productivity of the resin composition. The inorganic salt according to the resin composition of the present invention is preferably an oxophosphate, more preferably a phosphate, still more preferably an orthophosphate, still more preferably Group 2 from the viewpoint of improving the productivity of the resin composition. One or more phosphates selected from the group consisting of Group 4, Group 12, Group 13 and Group 14 metals, more preferably composed of Ti, Sn, Zn, Al, Zr, Mg, Hf and Ge. One or more phosphates selected from the group, more preferably tin phosphate.

The content of the inorganic salt in the resin composition of the present invention is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, still more preferably 0, from the viewpoint of improving the productivity of the resin composition. It is 0.01% by mass or more, and from the same viewpoint, it is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and further preferably 0.03% by mass or less.

The content of the inorganic salt in the resin composition of the present invention is preferably 0.001 part by mass or more with respect to 100 parts by mass of the modified hydroxycarboxylic acid polymer from the viewpoint of improving the productivity of the resin composition. It is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, and from the same viewpoint, preferably 0.1 parts by mass or less, more preferably 0.05 parts by mass or less, still more preferably. It is 0.03 part by mass or less.

The acid value of the resin composition of the present invention is preferably 50 mgKOH / g or less, more preferably 10 mgKOH / g or less, still more preferably 1 mgKOH / g or less, still more preferably 0.1 mgKOH, from the viewpoint of improving hydrolysis resistance. It is less than / g. The acid value is measured by the method described in Examples below.

[Example of a method for producing a resin composition containing a modified hydroxycarboxylic acid polymer]
Specific examples of the method for producing the resin composition of the present invention include a production method having a step of performing an alcoholic reaction between a hydroxycarboxylic acid polymer and an alcohol having 6 or more and 30 or less carbon atoms. More specifically, a hydroxycarboxylic acid polymer, an alcohol having 6 to 30 carbon atoms, and a catalyst are combined to form a reaction mixture, and the temperature of the reaction mixture is raised to a temperature sufficiently high for the alcoholesis to proceed. The resin composition can be produced by recovering the resin composition when the alcoholism is completed to a desired degree. An oxyhydrocarbon group is introduced at the terminal on the carboxylic acid side of the hydroxycarboxylic acid polymer by alcoholesis. The hydrocarbon groups of the oxyhydrocarbon groups introduced are derived from alcohols, as shown in the outline of the alcoholic reaction below.
R-OH + H- (hydroxycarboxylic acid unit) -C (O) OH → H-OH + H- (hydroxycarboxylic acid unit) -C (O) OR

As the hydroxycarboxylic acid polymer used as a raw material in the production method of this embodiment, a hydroxycarboxylic acid monomer may be polymerized by a known method, or a commercially available product may be used. Moreover, you may use the hydroxycarboxylic acid polymer which introduced the hydrolysis inhibitor as a raw material.

When a hydrolysis inhibitor is introduced into a hydroxycarboxylic acid polymer, examples of the hydrolysis inhibitor include carbodiimide compounds. Examples of the carbodiimide compound include a polycarbodiimide compound and a monocarbodiimide compound, and a polycarbodiimide compound is preferable from the viewpoint of improving hydrolysis resistance.

From the viewpoint of improving hydrolysis resistance, the amount of the hydrolysis inhibitor added is preferably 0.01 part by mass or more, more preferably 0.1 part by mass, based on 100 parts by mass of the hydroxycarboxylic acid polymer used as a raw material. It is by mass or more, more preferably 1 part by mass or more, and from the viewpoint of improving moldability and ease of spinning, it is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, still more preferably 5 parts by mass. It is less than a part.

Examples of the hydroxycarboxylic acid constituting the modified hydroxycarboxylic acid polymer include aliphatic hydroxycarboxylic acid, aromatic hydroxycarboxylic acid, phenylacetic acid derivative, and silicic acid derivative, and biodegradation of the modified hydroxycarboxylic acid polymer. Aliphatic hydroxycarboxylic acid is preferable from the viewpoint of excellent properties.

Examples of the aliphatic hydroxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyhexanoic acid, 6-hydroxyhexanoic acid, 3-hydroxypropionic acid, 3-. Examples thereof include hydroxyvaleric acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, leucic acid, ricinolic acid, ricineraidic acid, and celebronic acid.

The hydroxycarboxylic acid constituting the modified hydroxycarboxylic acid polymer is preferably more than hydroxyalkanoic acid, more preferably lactic acid, glycolic acid, hydroxybutyric acid and hydroxyhexanoic acid from the viewpoint of ensuring availability of raw materials and stable productivity. One or more selected from the group consisting of, more preferably one or more selected from the group consisting of lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid and 6-hydroxyhexanoic acid, still more preferably. Is lactic acid. In the production method of this embodiment, the lactone composed of the hydroxycarboxylic acid may be used as a raw material.

The hydrocarbon group of the alcohol used in the production method of this embodiment has 6 or more and 30 or less carbon atoms. The hydrocarbon group in the alcohol is preferably a linear or branched saturated or unsaturated hydrocarbon group from the viewpoint of availability, improved moldability, and ease of spinning, and more preferably straight. It is a chain or branched alkyl group, more preferably a straight chain alkyl group. The number of carbon atoms of the hydrocarbon group in the alcohol is 6 or more, preferably 8 or more, more preferably 12 or more, and the same, from the viewpoint of easy availability, improved moldability, and ease of spinning. From the viewpoint, it is 30 or less, preferably 22 or less, and more preferably 18 or less. Specific examples of such alcohols include, for example, a group consisting of hexanol, octanol, decanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), octadecanol (stearyl alcohol), and docosanol (behenyl alcohol). One or more selected from the above can be mentioned. The boiling point of the alcohol used in the production method of this embodiment is preferably equal to or higher than the melting point of the hydroxycarboxylic acid polymer used as a raw material, more preferably 150 ° C. or higher, further preferably 150 ° C. or higher, from the viewpoint of ensuring stable productivity. Is 200 ° C. or higher, more preferably 300 ° C. or higher, and from the viewpoint of availability, it is preferably 400 ° C. or lower, more preferably 350 ° C. or lower.

The amount of alcohol used is preferably 1 mass by mass with respect to 100 parts by mass of the hydroxycarboxylic acid polymer from the viewpoint of ease of spinning, improvement of moldability and ensuring production stability of the resin composition of the present invention. More than parts, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and from the same viewpoint, preferably 50 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less. Is.

The catalyst used in the production method of this embodiment is preferably from a group consisting of metals of Group 2, Group 4, Group 12, Group 13 and Group 14 of the Periodic Table, or a group of metal compounds thereof, from the viewpoint of advancing arcolisis. One or more selected, more preferably one or more selected from the group consisting of Ti, Sn, Zn, Al, Zr, Mg, Hf, Ge and their metal compounds, and further. It is preferably one or more selected from the group consisting of carboxylates and alkoxides of Ti, Sn, Zn, Al, Zr, Mg, Hf and Ge, and more preferably from Sn carboxylates and alkoxides. One or more selected from the above group, and more preferably tin 2-ethylhexanoate.

The amount of the catalyst used is preferably 1 ppm or more, more preferably 10 ppm or more, still more preferably 100 ppm or more in the reaction mixture from the viewpoint of advancing the alkolisis, and secures the hydrolysis resistance of the resin composition. From the viewpoint, it is preferably 10000 ppm or less, more preferably 1000 ppm or less, still more preferably 500 ppm or less.

A solvent may be used to mix each of the above components and perform alcoholesis. Examples of the solvent include aromatic compounds such as benzene, toluene and xylene, higher aliphatic compounds such as hexadecane, aromatic halides such as dichlorobenzene and chlorobenzene, and halogen-substituted aliphatic compounds such as dichloromethane, chloroform, dichloroethane and trichloroethane. Be done.

Alcolysis can be performed by heating and stirring a mixture containing each of the above components. The reaction temperature is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, still more preferably 190 ° C. or higher from the viewpoint of advancing arcolisis, and preferably from the viewpoint of preventing thermal decomposition of the hydroxycarboxylic acid polymer. It is 300 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 210 ° C. or lower. The reaction time is preferably 0.1 hour or more, more preferably 1 hour or more, still more preferably 2 hours or more, preferably 10 hours or less, more preferably 5 hours or less, still more preferably, from the viewpoint of advancing arcolisis. Is less than 4 hours.

The production method of this embodiment may further include a purification step, and can reduce lactones and residual monomers which are by-products in the resin composition. For example, a method of subjecting the molten resin composition to a reduced pressure treatment and a method of cleaning with a solvent can be mentioned.

In the method subjected to the reduced pressure treatment, the temperature during the reduced pressure treatment is preferably 150 ° C. or higher, more preferably 160 ° C. or higher, still more preferably 170 ° C. or higher, from the viewpoint of reducing the lactone content in the resin composition. From the same viewpoint, the temperature is preferably 200 ° C. or lower, more preferably 190 ° C. or lower. The pressure of the reduced pressure treatment is an absolute pressure of 1000 Pa or less, more preferably 100 Pa or less, still more preferably 60 Pa or less, from the viewpoint of reducing the lactone content in the resin composition. The time of the reduced pressure treatment is preferably 0.1 hour or more, more preferably 0.5 hours or more, still more preferably 1 hour or more, from the viewpoint of reducing the lactone content in the resin composition, and the same. From the viewpoint, it is preferably 10 hours or less, more preferably 5 hours or less, still more preferably 3 hours or less.

In the method of cleaning with a solvent, the solvent used is preferably an organic solvent, more preferably an ester having a total carbon number of 2 or more and 6 or less, and further preferably, from the viewpoint of reducing the lactone content in the resin composition. Is an acetic acid ester having a total carbon number of 2 or more and 6 or less, and more preferably ethyl acetate.

The resin composition of the present invention can obtain fine fibers having an average fiber diameter of 6 μm or less when made into fibers, and is excellent in hydrolysis resistance even when made into fine fibers. Can be suitably used as a raw material for.

[fiber]
The fiber of the present invention contains the modified hydroxycarboxylic acid polymer of the present invention or the resin composition of the present invention. Regarding the fiber diameter of the fiber of the present invention, the average fiber diameter when expressed as a circle-equivalent diameter is preferably 6 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less from the viewpoint of functional expression as fine fibers. From the viewpoint of ensuring the durability of the fiber, it is preferably 0.1 μm or more, more preferably 0.5 μm or more. The average fiber diameter is measured by the method described in Examples below.

Since the fiber of the present invention has excellent biodegradability and hydrolysis resistance, it is suitable not only for products used in a dry state but also for products used in a wet state such as a washroom, kitchen, and bathroom. Can be used for.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The pressures listed are absolute pressures.

[Synthesis of Resin Composition Containing Modified Hydroxycarboxylic Acid Polymer]
Synthesis example 1
In a stainless steel reaction tank equipped with a stirring motor, a stainless steel stirring blade, a return tube and a cooling tube, 100 parts by mass of polylactic acid (manufactured by Nature Works: weight average molecular weight = 100,000) as a hydroxycarboxylic acid polymer and cetanol as an alcohol. (Manufactured by Kao Co., Ltd .: Calcol 6098) 9 parts by mass and 200 ppm of tin 2-ethylhexanoate were introduced into polylactic acid, and alcoholesis was performed at 200 ° C. for 3 hours. After completion of the reaction, 1.58 times mol of phosphoric acid was added to 2-ethylhexanoic acid. Subsequently, the temperature in the reaction vessel was adjusted to 180 ° C., and the pressure was reduced at 54 Pa for 2 hours to remove lactide. After pulverizing the solid obtained by cooling, as a lactide removal step, the solid is suspended in ethyl acetate having the same mass as the total mass of the alcohol and the hydroxycarboxylic acid polymer introduced as raw materials to obtain the solid. The operation of separating the alcohol was performed twice. The solid matter obtained by the lactide removing step was dried in a dehumidifying dryer at 80 ° C. and 1 kPa or less for 12 hours to obtain a resin composition. The analytical values are shown in Table 1.

Synthesis example 2
A resin composition was obtained under the same conditions as in Synthesis Example 1 except that the time of alcoholesis was 3.5 hours and lactide was not removed. The analytical values are shown in Table 1.

Synthesis example 3
A resin composition was obtained under the same conditions as in Synthesis Example 1 except that the amount of cetanol was 7.5 parts by mass. The analytical values are shown in Table 1.

Synthesis example 4
Polylactic acid (manufactured by Nature Works, weight average molecular weight = 100,000) is put into a constant temperature and humidity chamber (manufactured by ESPEC: PL-3KPH) and stored at 85 ° C. and 95 RH% at high temperature and high humidity for 24 hours. Hydrolysis was performed. The remaining water was removed with a dehumidifying dryer under the condition of 1 kPa or less over 12 hours to obtain a resin composition. The analytical values are shown in Table 1.

Synthesis example 5
A resin composition was obtained under the same conditions as in Synthesis Example 1 except that 2.7 parts by mass of lauryl alcohol (manufactured by Kao Corporation: Calcol 2098) was introduced as the alcohol. The analytical values are shown in Table 1.

Synthesis example 6
A resin composition was obtained under the same conditions as in Synthesis Example 1 except that 4.7 parts by mass of behenyl alcohol (manufactured by Higher Alcohol Industry: Behenyl alcohol 65) was introduced as the alcohol. The analytical values are shown in Table 1.

Synthesis example 7
Polycaprolactone (manufactured by Injevity: weight average molecular weight = 160,000) 100 parts by mass as a hydroxycarboxylic acid polymer, and cetanol (manufactured by Kao: Calcol 6098) 20 parts by mass and 200 ppm of tin 2-ethylhexanoate were introduced with respect to polycaprolactone, and alcoholesis was performed at 170 ° C. for 1.5 hours. After completion of the reaction, 1.58 times by mole of phosphoric acid was added to tin 2-ethylhexanoate. The solid obtained by cooling was pulverized and further dissolved in chloroform to prepare a 20% by mass chloroform solution. The precipitate obtained by adding 5% by mass of methanol to the chloroform solution was filtered off. The precipitate obtained by filtration was dried in a dehumidifying dryer at 40 ° C. and 1 kPa or less for 12 hours. The solid matter obtained by drying was pressed against a mesh having an opening of 1 mm and crushed to obtain a resin composition. The analytical values are shown in Table 2.

[Analysis of Resin Composition Containing Modified Hydroxycarboxylic Acid Polymer]
(Amount of terminal oxyhydrocarbon groups, amount of lactide)
The resin composition obtained in each synthesis example or a polylactic acid resin that has not been denatured and has not been hydrolyzed (hereinafter, simply referred to as a polylactic acid resin) is dissolved in dehydrogenated chloroform, and NMR, manufactured by Agent Co., Ltd., The amount of oxyhydrogen group at the terminal and the amount of lactide were determined by proton NMR measurement using MR400.

(Weight average molecular weight)
The weight average molecular weight of the resin composition or polylactic acid resin obtained in each synthetic example was determined by gel permeation chromatography under the following conditions.
Sample: 0.1 volume% chloroform solution Equipment: HLC-8220GPC (manufactured by Tosoh Corporation)
Column GMHHR-H + GMHHR-H (manufactured by Tosoh)
Column temperature 40 ° C
Sample injection volume 100 mL,
Flow rate 1.0 mL / min
Eluent 1 mmol / L fermin DM20 / chloroform), RI detection standard: polystyrene

(Acid value)
0.5 g of the resin composition or polylactic acid resin obtained in each synthesis example was precisely weighed, dissolved in 10 mL of chloroform, and diluted with 10 mL of benzyl alcohol to prepare a sample. The resulting sample was titrated with a 0.002N KOH ethanol solution using phenol red as an indicator. The acid value (mgKOH / g) calculated from the dropping volume of a 0.002N KOH ethanol solution was used as the initial acid value.

[Spinning process]
Examples 1-5, Comparative Examples 1-2
(Preparation of raw materials for spinning)
A hydrolysis inhibitor (manufactured by Nisshin Spinning Chemical Co., Ltd .: carbodilite) so as to have 3 parts by mass with respect to 100 parts by mass of the hydroxycarboxylic acid polymer as a raw material with respect to the resin composition or polylactic acid resin obtained in each synthesis example. LA-1) was added and mixed at 170 ° C. using a twin-screw kneader (manufactured by Toyo Seiki Seisakusho Co., Ltd .: Labplast Mill Micro) to prepare raw materials for spinning and used in the spinning process.

(Electric field spinning)
The raw material for spinning was fibrized by the molten electric field spinning apparatus 10 shown in FIG. 1 under the following conditions.
Melting temperature: 170 ° C
Discharge rate of melt: 2 g / min
Applied voltage: -20kV
Distance between the intersection of the virtual straight line extending from the fluid injection unit 23 in the injection direction and the collection unit and the discharge nozzle tip 14: 600 mm

The molten electric field spinning apparatus 10 shown in FIG. 1 faces a molten resin supply unit provided with a discharge nozzle 12 for discharging the raw material resin and a hopper 19 for supplying the raw material resin in the housing 11 and is separated from the discharge nozzle 12. It has a charged electrode 21 arranged at a position to be formed and an electrode portion provided with a high voltage generator 22 connected to the charged electrode 21. The discharge nozzle 12 includes a nozzle base 13 and a discharge nozzle tip portion 14. Separation means that the tip portion 14 of the discharge nozzle and the charging electrode 21 are separated from each other. The tip portion 14 of the discharge nozzle is grounded and grounded. The device 10 includes a fluid injection unit 23 on the lower side of the drawing from the virtual straight line connecting the molten resin supply unit and the electrode unit, and is located above the virtual straight line and the fluid injection. A collecting portion for collecting the fibers of the raw material resin is provided at a position facing the portion 23, and forms an ultrafine fiber manufacturing apparatus as a whole. The collection unit is configured by arranging a collection sheet 24 on a transfer conveyor 25 and supplying the collection sheet 24 from a roll-shaped collection sheet original fabric 24a onto the transfer conveyor 25. Further, the collecting portion is connected to the high voltage generator 22 or is grounded to the ground and electrically connected. The evaluation results of the fibers are shown in Table 1.

[Evaluation of fiber]
(Average fiber diameter)
Randomly select 300 or more fibers from photographs obtained by photographing the sample surface at 1000x, 2000x, and 5000x magnification with a scanning electron microscope (JSM-6510 manufactured by JEOL Ltd.). The diameter was measured. The arithmetic mean of these measured values was calculated and used as the average fiber diameter.

(Molecular weight change rate)
Deionized water and the fibers of Examples 1 to 5, Comparative Examples 1 and 2 or the pulverized product of Example 6 were added so as to be 4% by mass, and a DL-malic acid 50% solution was added so that the pH was 5. After adjusting by adding liquid malic acid (manufactured by Fuso Chemical Industry Co., Ltd.), the mixture was stored at 50 ° C. for one month. The fiber or pulverized product taken out from the storage solution was washed with ethanol and then dried in a dehumidifying dryer at 80 ° C. and 1 kPa or less for 12 hours to be used for measuring the weight average molecular weight. The weight average molecular weight of the polylactic acid resin before and after storage was measured, and the rate of change before and after storage was calculated by the following formula.
Molecular weight change rate (%) = (Weight average molecular weight after storage-Weight average molecular weight before storage) / Weight average molecular weight before storage x 100

From Table 1, it can be seen that in Examples 1 to 5, all of them were made into fine fibers by molten electric field spinning and had excellent hydrolysis resistance. On the other hand, in Comparative Example 1 using the resin composition of Synthesis Example 4 in which only hydrolysis was carried out without introducing an oxyhydrocarbon group, although it was made into fine fibers, it was inferior in hydrolysis resistance. Further, in Comparative Example 2 using the polylactic acid resin which was not denatured and was not hydrolyzed, the average fiber diameter of the obtained fibers was large, although there was no problem in stability. Further, as shown in Example 6 of Table 2, it can be seen that even when polycaprolactone was used, the hydrolysis resistance was excellent. In Example 6, instead of pulverization, it is also possible to make fine fibers by molten electric field spinning. In Example 6, the hydrolysis resistance of the crushed resin composition is evaluated, but it is reasonably presumed that the crushed resin composition is also excellent in hydrolysis resistance even when it is made into fine fibers.

Synthesis Examples 8-12
The resin composition obtained under the same conditions as in Synthesis 1 except that the hydroxycarboxylic acid polymer and the alcohol shown in Table 3 are used can be subjected to, for example, the spinning process described in the present specification to withstand hydrolysis. Fine fibers having excellent properties can be obtained.

The modified hydroxycarboxylic acid polymer and resin composition of the present invention can be suitably used as raw materials for fine fibers and the like.

10 Molten electric field spinning device 11 Housing 12 Discharge nozzle 13 Nozzle base 14 Discharge nozzle tip 19 Hopper 21 Charging electrode 22 High voltage generator 23 Fluid injection unit 24 Collection sheet 24a Collection sheet Original fabric 25 Conveyance conveyor 26 High voltage generation Device 27 Collection electrode A Air flow R Raw material resin F Fiber

Claims (10)

A lactone having 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of a modified hydroxycarboxylic acid polymer and a modified hydroxycarboxylic acid polymer whose terminal group is an oxyhydrocarbon group having 6 or more and 30 or less carbon atoms. A resin composition containing. The resin according to claim 1, wherein the mass ratio of the oxyhydrocarbon group to the hydroxycarboxylic acid unit (oxyhydrocarbon group / hydroxycarboxylic acid unit) in the modified hydroxycarboxylic acid polymer is 0.001 or more and 0.4 or less. Composition. The resin composition according to claim 1 or 2, wherein the modified hydroxycarboxylic acid polymer has a weight average molecular weight of 5000 or more and 100,000 or less. The resin composition according to any one of claims 1 to 3, further containing an inorganic salt. The resin composition according to claim 4, wherein the content of the inorganic salt is 0.001 part by mass or more and 0.1 part by mass or less with respect to 100 parts by mass of the modified hydroxycarboxylic acid polymer. The resin composition according to any one of claims 1 to 5, wherein the modified hydroxycarboxylic acid polymer is an ester of a copolymer containing polylactic acid, polycaprolactone, or a lactic acid unit. The resin composition according to any one of claims 1 to 6, which has an acid value of 50 mgKOH / g or less. A method for producing a resin composition containing a modified hydroxycarboxylic acid polymer, which comprises a step of performing an alcoholic reaction between a hydroxycarboxylic acid polymer and an alcohol having 6 or more and 30 or less carbon atoms. The production method according to claim 8, further comprising a purification step. A fiber containing the resin composition according to any one of claims 1 to 7.