JP7222923B2 - Nonwoven fabric manufacturing method - Google Patents

Description

The present invention relates to a method of making nonwoven fabrics comprising poly(3-hydroxyalkanoates), which are biodegradable polyesters.

In recent years, plastic waste has become a cause of 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 combustion heat. As one solution to such problems, the development of biodegradable plastics is gaining momentum.

Among them, biodegradable plastics derived from plants do not increase carbon dioxide in the atmosphere because the carbon dioxide released when they are burned is originally in the air. This is called carbon neutrality, and under the Kyoto Protocol, which imposes carbon dioxide reduction targets, it is emphasized, and active use of plant-derived biodegradable plastics is desired.

Recently, from the viewpoint of biodegradability and carbon neutrality, attention has been paid to aliphatic polyester-based resins as plant-derived plastics. Poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter referred to as P3HB3HH) ), poly(3-hydroxyalkanoate) such as poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (hereinafter sometimes referred to as P3HA), and polylactic acid are attracting attention. there is

However, the PHA is slow to crystallize and has a glass transition temperature (about 0 to 4°C) lower than room temperature. is bad. In particular, when trying to produce a nonwoven fabric by melt-spinning PHA, forming a web, and then pressurizing and heat-bonding it, the solidification of the resin is slow. Breakage, shrinkage of the web, etc. occur, making it difficult to produce a stable nonwoven fabric, and the quality of the nonwoven fabric obtained is also low.

As means for solving these problems, a method for producing a thermoplastic biodegradable polyester nonwoven fabric containing butylene succinate units to which a crystal nucleating agent is added has been disclosed (see Patent Documents 1 and 2). According to the method, the thermoplastic biodegradable polyester is melt-spun, and the web obtained by making the web is heated to a temperature of -5 ° C. or less (Patent Document 1), or the melting point (Tm) of the thermoplastic biodegradable polyester. Patent Document 2 describes that a nonwoven fabric that can retain its shape can be obtained by heat-pressing with rolls set to a temperature lower than 10° C. (Patent Document 2).

As another precedent example, a web of core-sheath composite fibers having a core component of P3HA resin and a sheath component of polybutylene succinate, polyethylene succinate, or a copolymer thereof was heated at a temperature 30° C. lower than Tm and at a temperature higher than Tm. A method of thermally bonding at a temperature of less than 100°C has been disclosed (see Patent Document 3).

JP-A-08-325916 JP-A-09-095848 JP-A-2000-160466

However, Patent Documents 1 and 2 do not specifically describe a nonwoven fabric using PHA as a thermoplastic biodegradable polyester. With this method, it is difficult to produce a nonwoven fabric. In addition, the method disclosed in Patent Document 3 has a problem that a nonwoven fabric composed only of P3HA such as P3HB3HV cannot be formed.

Therefore, the present invention provides good moldability of nonwoven fabrics containing poly(3-hydroxyalkanoate), and can also produce nonwoven fabrics containing essentially only poly(3-hydroxyalkanoate) as a resin component. Provide a possible manufacturing method.

The present inventor has made intensive studies to solve this problem, and according to a production method including a specific process, the moldability of a nonwoven fabric containing poly(3-hydroxyalkanoate) is good, and the resin component The inventors have found that it is also possible to produce a nonwoven fabric containing essentially only poly(3-hydroxyalkanoate) as the poly(3-hydroxyalkanoate), and completed the present invention.

That is, in one or more embodiments, the present invention provides, for example, the following method for producing a nonwoven fabric.

[1] Step A of obtaining fibers by melt-spinning a composition containing poly(3-hydroxyalkanoate) using a spinneret;
A step B of forming a web from the fibers obtained in step A to obtain a web;
and a step C of subjecting the web obtained in step B to pressure heat bonding,
A nonwoven fabric characterized in that the pressure heat bonding treatment temperature in the step C is (Tc-45) ° C. or higher and (Tc + 5) ° C. or lower [Tc: crystallization temperature of poly(3-hydroxyalkanoate)]. Production method.

[2] The method for producing a nonwoven fabric according to [1], wherein the temperature for the pressure heat-bonding treatment is (Tc-40)°C or higher and (Tc+0)°C or lower.

[3] The method for producing a nonwoven fabric according to [1] or [2], wherein the amount of the composition discharged per single hole from the spinneret in step A is 0.2 to 1.2 g/min.

[4] The method for producing a nonwoven fabric according to [3], wherein the amount of the composition discharged per single hole from the spinneret in step A is 0.2 to 0.7 g/min.

[5] The method for producing a nonwoven fabric according to any one of [1] to [4], wherein the web formation in step B is performed by a spunbond method.

[6] The method for producing a nonwoven fabric according to any one of [1] to [5], wherein the melt spinning temperature in step A is 145 to 190°C.

[7] The method for producing a nonwoven fabric according to any one of [1] to [6], wherein the composition further contains a crystal nucleating agent.

[8] The method for producing a nonwoven fabric according to [7], wherein the content of the crystal nucleating agent is 0.05 to 12 parts by weight per 100 parts by weight of poly(3-hydroxyalkanoate).

[9] The method for producing a nonwoven fabric according to any one of [1] to [8], wherein the composition further contains a lubricant.

[10] The method for producing a nonwoven fabric according to [9], wherein the content of the lubricant is 0.05 to 12 parts by weight per 100 parts by weight of poly(3-hydroxyalkanoate).

[11] The poly(3-hydroxyalkanoate) is poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co- 3-hydroxyhexanoate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) [1] to [ 10], the method for producing a nonwoven fabric according to any one of

Since the present invention has the above structure, the nonwoven fabric containing poly(3-hydroxyalkanoate) has good moldability, and the nonwoven fabric containing essentially only poly(3-hydroxyalkanoate) as a resin component. Fabrication is also possible.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the apparatus used for manufacture of the nonwoven fabric in an Example.

DETAILED DESCRIPTION OF THE INVENTION One or more embodiments of the invention are described below in detail. In addition, this invention is not limited to the following embodiment.

The method for producing a nonwoven fabric of the present invention is a method including the following steps A to C as essential steps. The nonwoven fabric manufacturing method of the present invention may include other steps.
Step A: A step of melt-spinning a composition containing poly(3-hydroxyalkanoate) using a spinneret to obtain a fiber Step B: A step of forming a web from the fibers obtained in Step A to obtain a web Step C : A step of subjecting the web obtained in step B to pressure heat bonding treatment

[Step A]
In step A, a composition containing poly(3-hydroxyalkanoate) (hereinafter sometimes referred to as a P3HA composition) is melt-spun to obtain fibers composed of the P3HA composition.

(P3HA composition)
The above P3HA composition is a composition containing P3HA as an essential ingredient. P3HA used in the present invention is a polymer containing 3-hydroxyalkanoic acid (3HA) as an essential monomer component. Among them, P3HA preferably has the formula (1): [--CHR--CH ₂ --CO--O--] (in formula (1), R is an alkyl group represented by C _n H _2n+1 , n is 1 is an integer of 15 or less).

P3HA is generally classified into P3HA produced by microorganisms and chemically synthesized P3HA obtained by chemical synthesis such as ring-opening polymerization of lactone. These P3HAs have different structures. Microorganism-produced P3HA has only D-isomer (R-isomer) monomer structural units and has optical activity, whereas chemically synthesized P3HA has D-isomer (R-isomer) and L-isomer It is optically inactive because the monomeric structural units derived from the (S-form) are randomly combined.

The P3HA is preferably a P3HA containing 3-hydroxybutyrate units. Such PHAs include, for example, poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxy valerate) (P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) noate) (P3HB3HH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxy Butyrate-co-3-hydroxyoctadecanoate) and the like are preferable from the viewpoint of easy industrial production. Among these, P3HB, P3HB3HV, P3HB3HV3HH, P3HB3HH and P3HB4HB are particularly preferred, and P3HB3HH is more preferred.

When the P3HA is a P3HA containing a 3-hydroxybutyrate unit structure, the average composition ratio of the repeating units (monomer structural units) is not particularly limited, but from the viewpoint of the balance between flexibility and strength, poly(3-hydroxybutyrate rate) is preferably 80 to 99 mol%, more preferably 85 to 97 mol%.

P3HA can be produced by a known or commonly used method. When the P3HA is microbially-produced P3HA, the microorganism used for the production of the P3HA is not particularly limited as long as it has the ability to produce P3HAs. For example, Bacillus megaterium, which was discovered in 1925, was the first P3HB-producing fungus. Natural microorganisms such as Alcaligenes latus are known, and P3HB is accumulated in these microorganisms.

Examples of bacteria producing copolymers containing hydroxybutyrate units and other hydroxyalkanoate units include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes, which produces P3HB4HB. eutrophus) and the like are known. In particular, regarding P3HB3HH, in order to increase the productivity of P3HB3HH, Alcaligenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) (T.Fukui, Y.Doi, J.Bateriol) into which the gene of the P3HA synthase group was introduced. ., 179, pp. 4821-4830 (1997)) are more preferred, and microbial cells obtained by culturing these microorganisms under appropriate conditions and accumulating P3HB3HH in the cells are used. In addition to the above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced may be used according to the PHA to be produced, or culture conditions including the type of substrate may be optimized.

The molecular weight of P3HA is not particularly limited as long as it substantially exhibits sufficient physical properties for the intended use. If the molecular weight is too low, the strength of the resulting molded article may be lowered. On the other hand, if it is too high, the workability will deteriorate, and molding may become difficult. Taking these into consideration, the weight average molecular weight range of P3HA 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 that measured from polystyrene conversion 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 melt flow rate of P3HA measured at 160° C. under a load of 5 kg is preferably 0.1 to 100 g/10 minutes, more preferably 1 to 50 g/10 minutes, and 10 to 40 g/10 minutes. is more preferred. If the melt flow rate is too low, the fluidity of the molten resin is insufficient, and if it is too high, the fluidity is too high.

P3HA may be used alone or in combination of two or more of the above P3HAs. Further, for example, in the case of P3HB3HH, only one type of P3HB3HH may be used, or P3HB3HH may be a mixture of two or more types of 3HB having different composition percentages.

The content of P3HA in the P3HA composition of the present invention is not particularly limited, but is preferably 80% by weight or more, more preferably 85% by weight or more, and still more preferably 90% by weight or more, while the upper limit is 100% by weight. However, for example, it may be 98% by weight or less or 95% by weight or less. A P3HA content of 80% by weight or more tends to further improve the biodegradability of the resulting nonwoven fabric. According to the nonwoven fabric production method of the present invention, even when the P3HA content is as high as 80% by weight or more, the nonwoven fabric can be produced with excellent formability, which is very beneficial.

The proportion of P3HA in the resin component contained in the P3HA composition of the present invention is not particularly limited, but is preferably 80 to 100 wt%, more preferably 90 to 100 wt%, still more preferably 95 to 100 wt%. . According to the method for producing a nonwoven fabric of the present invention, it is possible to produce a nonwoven fabric with good moldability even when the proportion of P3HA in the resin component is high (for example, 80% by weight or more).

The P3HA composition of the present invention preferably further contains a crystal nucleating agent. The crystal nucleating agent is not particularly limited as long as it is a compound having an effect of promoting the crystallization of P3HA. Examples include boron nitride, titanium oxide, talc, layered silicate, calcium carbonate, chloride minerals such as sodium and metal phosphates; sugar alcohol compounds derived from natural sources such as erythritol, galactitol, mannitol and arabitol; pentaerythritol; polyvinyl alcohol; chitin; carboxylic acid salts; aliphatic alcohols; aliphatic carboxylic acid esters; dicarboxylic acid derivatives such as dimethyl adipate, dibutyl adipate, diisodecyl adipate and dibutyl sebacate; and a cyclic compound having a functional group selected from and O in the molecule; sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene) sorbitol; phosphate compounds; higher fatty acid bisamides and higher fatty acid metal salts; branched polylactic acid; low-molecular-weight poly-3-hydroxybutyric acid. Among these, pentaerythritol, sugar alcohol compounds, polyvinyl alcohol, chitin, chitosan, etc. are preferred, and pentaerythritol is more preferred, from the viewpoint of improving the crystallization rate and being mixed with fibers. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Pentaerythritol is not particularly limited as long as it is generally available, and reagents or industrial products can be used. Examples of reagents include those manufactured by Wako Pure Chemical Industries, Ltd., manufactured by Sigma-Aldrich, manufactured by Tokyo Chemical Industry Co., Ltd., and manufactured by Merck. Pentalit) and products of Toyo Chemicals Co., Ltd., but not limited to these.

Some commonly available reagents and products contain, as impurities, oligomers such as dipentaerythritol and tripentaerythritol formed by dehydration condensation of pentaerythritol. The above oligomers have no effect on the crystallization of polyhydroxyalkanoates, but do not inhibit the crystallization effect of pentaerythritol. Therefore, it may contain an oligomer.

The content of the crystal nucleating agent in the P3HA composition is not particularly limited, but is preferably 0.05 to 12 parts by weight, more preferably 0.1 to 10 parts by weight, and 0.5 to 8 parts by weight with respect to 100 parts by weight of P3HA. more preferably 1 to 5 parts by weight. By setting the content of the crystal nucleating agent to 0.05 parts by weight or more, a more excellent effect of promoting crystallization can be obtained, so that the productivity of the nonwoven fabric tends to be improved. On the other hand, by setting the content of the crystal nucleating agent to 12 parts by weight or less, there is a tendency not to cause adverse effects such as a decrease in viscosity during processing and a decrease in fiber physical properties while maintaining a sufficient crystallization rate acceleration effect. be.

Preferably, the P3HA composition further comprises a lubricant. The lubricant is not particularly limited as long as it is a compound having the effect of imparting lubricity to the PHA. For example, fatty acid amides such as behenamide, stearamide, erucamide and oleamide; alkylene fatty acid amides such as methylenebisstearicamide and ethylenebisstearic acid amide; polyethylene waxes; oxidized polyester waxes; glycerin monostearate. , glycerin monobehenate and glycerin monolaurate; organic acid monoglycerides such as succinic saturated fatty acid monoglyceride; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate and sorbitan laurate; diglycerin stearate , polyglycerin fatty acid esters such as diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate and decaglycerin laurate; and higher alcohol fatty acid esters such as stearyl stearate. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Among the above lubricants, fatty acid amides and polyglycerin fatty acid esters are specifically preferred as compounds having the effect of imparting external lubricity. Examples of fatty acid amides include fatty acid monoamides and bisamides. The fatty acid (fatty acid portion) constituting the fatty acid amide has a moderately high melting point and is preferably a fatty acid having 12 to 30 carbon atoms, more preferably 18 to 18 carbon atoms, from the viewpoint of suppressing deterioration of processability during melt processing. 22 fatty acids, and examples thereof include higher fatty acids such as erucic acid, palmitic acid, and oleic acid. Specific examples of fatty acid amides include behenic acid amide, erucic acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis and erucic acid amide. Polyglycerin fatty acid esters include, for example, glycerin monoester, glycerin diester, glycerin triester (e.g., glycerin diacetomonolaurate, glycerin diacetomonooleate, glycerin diacetomonostearate, glycerin diacetomonocaprylate, glycerin diaceto glycerine diacetomonoesters such as cetomonodecanoate, etc.). Commercially available polyglycerol fatty acid esters include, for example, Rikemal PL-012 (manufactured by Riken Vitamin) and DAIFATTY (manufactured by Daihachi Chemical Industry). Fatty acid amides and polyglycerin fatty acid esters are more preferable in terms of availability and high effectiveness.

The content of the lubricant in the P3HA composition is not particularly limited as long as it can reduce the friction between the polyhydroxyalkanoate and the metal surface of the extruder or spinning machine and prevent mutual adhesion between fibers. 0.05 to 12 parts by weight is preferred, 0.1 to 10 parts by weight is more preferred, 0.5 to 8 parts by weight is even more preferred, and 3 to 10 parts by weight is particularly preferred. By setting the content of the lubricant to 0.05 parts by weight or more, the friction in the extruder or spinning machine is suppressed, the decomposition of P3HA due to shear heat generation is suppressed, and the fibers discharged from the nozzle are prevented from sticking to each other. tend to be On the other hand, by setting the lubricant content to 12 parts by weight or less, the P3HA in the extruder melts more efficiently, and as a result, fiber breakage is suppressed without making the fiber too hard, further improving productivity. tend to

The P3HA composition further contains other ingredients such as plasticizers, inorganic fillers, organic fillers (such as cellulose), antioxidants, UV absorbers, colorants such as dyes and pigments, and antistatic agents. may be

Although the plasticizer is not particularly limited, for example, adipate compounds such as diethylhexyl adipate, dioctyl adipate and diisononyl adipate; polyether ester compounds such as polyethylene glycol dibenzoate, polyethylene glycol dicaprylate and polyethylene glycol diisostearate compounds; benzoic acid ester compounds; epoxidized soybean oil; epoxidized fatty acid 2-ethylhexyl; sebacic acid monoesters; These may be used individually by 1 type, and may be used in combination of 2 or more type.

Among the above plasticizers, polyether ester compounds are preferable in terms of availability and high plasticizing effect. The content of the plasticizer in the P3HA composition is not particularly limited, and can be appropriately selected, for example, within the range of 3 to 25 parts by weight with respect to 100 parts by weight of P3HA.

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, metal powder, and kaolin. , graphite, molybdenum disulfide, zinc oxide, and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Among the above inorganic fillers, titanium oxide and/or calcium carbonate are preferable from the viewpoint of high strength-increasing and biodegradability-promoting effects. The content of the inorganic filler in the P3HA composition is not particularly limited, and can be appropriately selected, for example, in the range of 1 to 10 parts by weight with respect to 100 parts by weight of P3HA.

The P3HA composition may contain resin components other than P3HA (other resin components). Other resin components include biodegradable resins such as petroleum-derived resins such as polylactic acid, polybutylene adipate terephthalate, polybutylene succinate adipate, and polybutylene succinate, and natural polymers such as starch and cellulose. be done. Also, known thermoplastic resins (polyvinyl chloride resin, polystyrene resin, ABS resin, etc.) and thermosetting resins (epoxy resin, etc.) can be added. In addition, general-purpose engineering plastics such as polyethylene terephthalate-based resins, polybutylene terephthalate-based resins, polycarbonate-based resins, and polyamide-based resins are also used as other resin components. The content of other resin components is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 5% by weight or less with respect to the total amount (100% by weight) of the resin components. Other resin components can be used singly or in combination of two or more.

The method for producing a nonwoven fabric of the present invention includes a step A of melt-spinning a composition containing at least poly(3-hydroxyalkanoate), a step B of forming a web from the fibers obtained in step A, and a step B. A step C of subjecting the obtained web to pressure heat bonding treatment is included in this order, thereby producing a biodegradable nonwoven fabric using PHA. As a method of applying these processes to process nonwoven fabrics, there is a general method such as the spunbond method (fibers coming out of a spinneret pass through a suction device called an ejector and are stretched into a web. (a method of forming a web), a meltblown method (a method of ejecting fibers from a spinneret to form a web), and the like.

First, in step A, for example, using a melt extruder, the P3HA composition is melted and continuously extruded through a spinneret (also called a spinning die) to form fibers composed of the P3HA composition. The melt extruder may be a general device as long as it is possible to maintain the molecular weight and melt viscosity of the P3HA to be used appropriately. Either extrusion device may be used. The former is suitable for small-scale production, and the latter is suitable for industrial production.

The cylinder temperature and the die exit temperature of the melt extruder may be adjusted according to the molecular weight and monomer composition of the P3HA used so that the melt viscosity of the P3HA is appropriately maintained. Also, the melt spinning temperature of the fiber is preferably 145 to 190°C, more preferably 150 to 190°C, still more preferably 150 to 180°C. By setting the spinning temperature to 145° C. or higher, the PHA composition can be sufficiently dissolved, so spinning tends to be further stabilized. On the other hand, by setting the spinning temperature to 190° C. or lower, thermal decomposition of the resin is suppressed, spinning is further stabilized, and the physical properties of the obtained fiber tend to be further improved. The melt spinning temperature refers to the temperature in the highest temperature range among the temperatures applied during fiberization of the P3HA composition.

The P3HA composition is melted and extruded through a spinning die while adjusting the flow rate to keep the discharge rate ^constant . By setting the opening area to 0.15 mm ² or more, breakage during spinning tends to be further suppressed. On the other hand, by setting the opening area to 3.5 mm ² or less, the fiber does not become too thick and the time required for solidification does not become too long. It tends to get better.

The discharge rate can be arbitrarily selected based on the final required fiber diameter and the spinning speed during production. 2 to 1.2 g/min is preferred, and 0.2 to 0.7 g/min is more preferred. By setting the discharge rate to 0.2 g/min or more, the fibers tend to be not too thin and yarn breakage is further suppressed. On the other hand, by setting the discharge rate to 1.2 g/min or less, the yarn does not become too thick, the solidification of the fibers proceeds rapidly, and mutual adhesion of the fibers tends to be suppressed.

In order to suppress decomposition of the resin due to heat during extrusion, the residence time of the resin inside the spinning machine is preferably 30 minutes or less, more preferably 15 minutes or less.

The ambient temperature for extrusion from the spinneret is not particularly limited, and can be adjusted appropriately within the range of 5 to 40°C, for example.

[Step B]
Next, in step B, the fibers composed of the P3HA composition extruded from the spinneret in step A, ie, the fibers obtained by melt-spinning the P3HA composition, are formed into a web to obtain a web. In this process, the fibers (spun filaments) made up of the P3HA composition are drawn and thinned (to become drawn filaments) to the desired fineness, and placed on a collecting surface such as a conveyor moving in the machine direction (MD). deposited on top to form a long fiber web.

When the nonwoven fabric is produced by the spunbond method (that is, when the web formation in the step B is performed by the spunbond method), a sucking device such as an ejector is used to draw and thin the nonwoven fabric by air stretching. For example, when using an ejector 3 as shown in FIG. 1, it is possible to adjust the spinning speed by adjusting the pressure of the air traction. A higher air pressure increases the spinning speed. The air pressure is preferably 0.2-7.0 Kgf/cm ² , more preferably 0.5-5.0 Kgf/cm ² . If it is lower than 0.2 Kgf/cm ² , it is difficult to obtain a sufficient spinning speed, and if it is higher than 7 Kgf/cm ² , the spinning speed tends to exceed 7000 m/min, which is the spinning speed that enables stable spinning. The spinning speed by air drawing is preferably 500 to 7000 m/min, more preferably 700 to 7000 m/min, even more preferably 700 to 5000 m/min, particularly preferably 700 to 3000 m/min. In this spinning speed range, solidification of fibers made of the P3HA composition that can ensure spinnability is obtained. When the spinning speed is slow, the produced nonwoven fabric may shrink when cooled, and a homogeneous and good nonwoven fabric may not be obtained. The upper limit of the take-up speed is not particularly limited, but if it exceeds 7,000 m/min, the strength of the obtained fiber does not change, so it is not necessary to make it higher than 7,000 m/min. The longer the distance from the suction device to the collecting surface, the better, preferably 80 cm or more. When the length is 80 cm or more, the solidification of the fibers proceeds rapidly, the fibers are less likely to adhere to each other in the suction device, and there is a tendency to suppress yarn breakage. Also, by drawing suction from below the collecting surface, shrinkage of the web tends to be reduced.

In step B, before drawing and thinning the fibers (spun filaments) extruded from the spinneret in step A, rectified air is applied by a device that provides rectified air such as the quench 2 shown in FIG. Giving is preferred. The straightening air is also called a quenching air, and has a function of stabilizing the flow of yarn. It is also possible to cool the spinning filaments by using a cooled gas. The quenching wind is preferably emitted through a net or mesh and sent uniformly to the yarn. In the case of the web forming apparatus, the quenching air is preferably blown from the same direction as the web forming conveyor, and may be blown from one side or both sides of the yarn. The temperature of the quenching air is preferably 5-40°C, more preferably 10-30°C. If the temperature is lower than 5°C, residual stress may occur in the fibers, causing the fibers to crimp. If the temperature is higher than 40°C, the solidification of the resin becomes insufficient and the fibers stick together. The wind speed of the quench wind is preferably 0.1 to 1.5 m/sec. If it is lower than 0.1 m/sec, the rectifying effect tends to be low, and if it is higher than 1.5 m/sec, the quenching wind is too strong, which conversely causes turbulence in the yarn, causing the fibers to stick together or break. may occur.

The fibers (stretched filaments) air-pulled by the ejector 3 are collected on a conveyor 4, for example, as shown in FIG. 1, and the conveyor runs to form a sheet-like web. Suction from the inside of the collecting surface of the conveyor tends to reduce web shrinkage. By changing the line speed, which is the operating speed of the conveyor, the basis weight of the nonwoven fabric can be adjusted when the discharge amount during melt spinning is the same. By increasing the line speed, the fabric weight can be reduced, but if the line speed is increased too much, there is a risk of shrinkage or breakage of the web.

[Step C]
Next, in step C, the web obtained in step B is heat-bonded under pressure. As a method of pressurized heat bonding, for example, a thermal embossing roll in which the surfaces of a pair of upper and lower rolls are respectively engraved, or a roll in which one roll surface is flat (smooth) and the other roll surface is engraved. It is possible to apply thermal pressure bonding using various rolls such as a hot embossing roll consisting of a combination of rolls, a hot calender roll consisting of a pair of upper and lower flat (smooth) rolls, and an air through method that passes hot air in the thickness direction of the nonwoven web. I can. Among them, thermal bonding using a thermal embossing roll, which can maintain adequate air permeability while improving mechanical strength, can be preferably employed.

The pressure heat bonding treatment temperature in step C, that is, the surface temperature of the pressure heat bonding roll is (Tc-45) ° C. or higher and (Tc + 5) ° C. or lower, (Tc - 40) ° C. or higher and (Tc + 0) ° C. The following are preferred. Note that Tc is the crystallization temperature of P3HA measured by the method described later. By setting the temperature of the pressurized heat bonding treatment to this temperature range, the fibers made of the PHA composition can be crystallized and the fibers can be adhered to each other to maintain the shape of the nonwoven fabric, and at the same time, the peeling of the sheet and the generation of fluff can be prevented. can be suppressed. On the other hand, if pressure heat bonding is performed outside this temperature range, the fibers cannot be solidified, and in addition to sticking to the roll, the shape of the nonwoven fabric cannot be maintained, and the nonwoven fabric shrinks or breaks.

It is also effective to apply a constant pressure between the two rolls of the pressure heat bonding rolls. When using an embossing roll, it is common to use an embossing roll with an engraved roll surface and a rubber backup roll with a flat (smooth) roll surface. The pressure required for pressurization should be such that the engraving pattern can be imparted to the nonwoven fabric at the optimum temperature at which the crystallization of P3HA proceeds and the mechanical strength can be maintained. The effective pressure between the pressure hot bonding rolls is preferably 20-60 Kg/cm, more preferably 30-50 Kg/cm. When the pressure of the pressurized heat-adhesive roll is lower than 20 kg/cm, the engraving pattern is difficult to impart and the strength may be lowered. On the other hand, if it is higher than 60 Kg/cm, excessive stress is applied to the nonwoven fabric, and the nonwoven fabric may break.

The crystallization temperature of P3HA is the temperature measured by the following apparatus, conditions and method.
- Measurement method: Differential Scanning Calorimetry (DSC)
・Measuring device: Hitachi Hightex Science EXSTAR6000 series DSC6200
・Measurement sample: 5 to 10 mg of P3HA was placed in an aluminum pan, covered with a lid, and crimped.
- Measurement conditions: After raising the temperature from 25°C to 180°C at a rate of 10°C/min, the temperature is lowered at a rate of 10°C/min to 25°C. Nitrogen gas is flowed at 50 mL/min during the measurement.
・Specification of crystallization temperature: The exothermic peak seen in the temperature-lowering process is defined as the crystallization peak, and the peak top is defined as the crystallization temperature.

The shape of the engraving applied to the hot embossing roll is not particularly limited, and examples thereof include circles, ovals, squares, rectangles, parallelograms, rhombuses, regular hexagons and regular octagons.

When the fibers present in the embossed pattern portion are partially heat-bonded using a heated embossing roll, the pressure contact area ratio of the embossing roll is preferably 5 to 50%. By setting the pressure contact area ratio to 5% or more, the mechanical strength of the nonwoven fabric tends to be improved and good dimensional stability can be obtained because a certain amount of fused dots is secured. On the other hand, by setting the pressure contact area ratio to 50% or less, stiffening of the nonwoven fabric tends to be suppressed, and flexibility tends to be further improved.

Through step C, a nonwoven fabric composed of the P3HA composition is obtained. The nonwoven fabric manufacturing method of one or more embodiments of the present invention may include other steps in addition to steps A to C as described above, and the other steps include, for example, before step C , includes a step of temporarily fixing the web obtained in step B, and the like. For example, as shown in FIG. 1, by installing the temporary fixing roll 5 on the conveyor, the flow of the web is stabilized, and the web can be guided to the pressurized heat bonding roll 6 in that state.

In the nonwoven fabric manufacturing method of one or more embodiments of the present invention, Steps A to C may be performed continuously or discontinuously. In particular, it is preferable to continuously perform steps A to C in that the nonwoven fabric can be produced more efficiently. The speed of performing steps A to C is not particularly limited, but for example, the time from obtaining fibers in step A to completing step C is preferably 30 seconds to 3 minutes, more preferably 40 minutes. seconds to 1 minute.

In one or more embodiments of the present invention, nonwoven fabrics can be made, for example, with the apparatus shown in FIG.
First, in step A, a composition containing P3HA is melted and extruded from a spinneret 1 for melt spinning to obtain fibers a (spun filaments).
Next, in step B, the fibers a are formed into a web to obtain a web b. Specifically, first, a rectified air is applied to the fibers a by the quench 2 . Next, the fibers a are air-pulled by an ejector 3 to be pulled and thinned to a predetermined fineness (stretched filaments), and deposited on a conveyor 4 moving in the machine direction (MD) to form a long fiber web b. Form.
Next, before carrying out step C, the long fiber web b is passed through a temporary fixing roll 5 placed on a conveyor 4 and guided to a pressure bonding roll 6 .
Next, in step C, the long fiber web b is pressurized and heat-bonded at a predetermined temperature by the pressurizing and heat-bonding roll 6 to obtain a long-fiber nonwoven fabric c. One of the pressure heat bonding rolls 6 is an embossed roll with an engraved roll surface, and the other can be a rubber backup roll with a flat (smooth) roll surface.
After that, the obtained long-fiber nonwoven fabric c is taken up by the take-up roll 7 .

The tensile strength of the nonwoven fabric obtained by the manufacturing method of one or more embodiments of the present invention may be appropriately determined according to the application and purpose. The tensile strength in the direction is preferably 8 N/50 mm or more, more preferably 10 N/50 mm or more, still more preferably 15 N/50 mm or more, and particularly preferably 20 N/50 mm or more. In addition, the tensile strength in the CD direction measured according to JIS L 1096 is preferably 5 N/50 mm or more, more preferably 10 N/50 mm or more, further preferably 15 N/50 mm or more, and 20 N /50 mm or more is even more preferable, and 40 N/50 mm or more is particularly preferable.

The tear strength of the nonwoven fabric obtained by the production method of one or more embodiments of the present invention may be appropriately determined according to the application and purpose, but from the viewpoint of increasing the strength, the MD measured according to JIS L 1096 The directional tear strength is preferably 3 N/50 mm or more, more preferably 5 N/50 mm or more, still more preferably 10 N/50 mm or more, and particularly preferably 15 N/50 mm or more. In addition, the tear strength in the CD direction measured according to JIS L 1096 is preferably 2 N/50 mm or more, more preferably 5 N/50 mm or more, further preferably 10 N/50 mm or more, and 15 N /50 mm or more is particularly preferable.

The nonwoven fabric obtained by the method for producing a nonwoven fabric of the present invention can be used for various known or common applications, such as agriculture, fishery, forestry, clothing, non-clothing textile products (eg, curtains, carpets, bags, etc.), sanitary products, gardening, and automobiles. It can be suitably used in members, building materials, medicine, 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 P3HB3HH KNK-005 strain (see US Pat. No. 7,384,766) was used for culture production of P3HB3HH.

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 . 15 w/v% _KH2PO4 , (pH _6.8 ).

The composition of the pre-culture medium is 1.1 w/v% Na ₂ HPO ₄ .12H ₂ O, 0.19 w/v% KH ₂ PO ₄ , 1.29 w/v% (NH ₄ ) ₂ SO ₄ , 0.1 w /v% _{MgSO4.7H2O ,} 0.5v/v% trace metal salt solution (0.1N hydrochloric acid, 1.6w/ _{v % FeCl3.6H2O} , 1w/v% _CaCl2.2H2O , 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). Palm oil was used as a carbon source and added all at once at a concentration of 10 g/L.

The composition of the P3HB3HH production medium is 0.385 w/v% _{Na2HPO4-12H2O} , 0.067 _w /v% _KH2PO4 , 0.291 w/v% ( _NH4 ) _{2SO4 , 0.1} w _/ v. /v% _{MgSO4.7H2O ,} 0.5v/v% trace metal salt solution (0.1N hydrochloric acid, 1.6w _/ v _{% FeCl3.6H2O} , 1w/v% _CaCl2.2H2O , 0.02 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: manufactured by Cognis Japan).

First, the KNK-005 strain glycerol stock (50 μL) was inoculated into a seed medium (10 mL) and cultured for 24 hours to perform 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 culture temperature was 33° C., the agitation rate was 500 rpm, the aeration rate was 1.8 L/min, and the pH was controlled between 6.7 and 6.8 for 28 hours 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. The culture temperature was 28° C., the stirring speed was 400 rpm, the aeration rate was 6.0 L/min, and the 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, and after completion of the cultivation, the cells were collected by centrifugation and washed with methanol. It was then lyophilized.

100 mL of chloroform was added to 1 g of the dried cells obtained above, and the mixture was stirred at room temperature for a whole day and night to extract P3HB3HH in the cells. After removing the bacterial cell residue by filtration, it was concentrated with an evaporator until the total volume became 30 mL, then 90 mL of hexane was gradually added, and the mixture was allowed to stand for 1 hour while slowly stirring. After the precipitated P3HB3HH was separated by filtration, it was vacuum-dried at 50° C. for 3 hours to obtain polyhydroxyalkanoate A1 (P3HB3HH).

The 3HH composition of the obtained P3HB3HH was analyzed by gas chromatography as follows. 2 mL of sulfuric acid-methanol mixture (15:85) and 2 mL of chloroform were added to 20 mg of P3HB3HH, and the mixture was sealed and heated at 100° C. for 140 minutes to obtain methyl ester of P3HB3HH 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. Furthermore, 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. The gas chromatograph was GC-17A manufactured by Shimadzu Corporation, and the capillary column was NEUTRA BOND-1 manufactured by GL Science (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 conditions were such that the initial temperature was raised from 100 to 200°C at a rate of 8°C/min, and further from 200 to 290°C at a rate of 30°C/min. As a result of analysis under the above conditions, it was confirmed that the obtained P3HB3HH had a composition percentage of 3-hydroxyhexanoate (3HH) monomer of 5.4 mol %. Further, the weight average molecular weight Mw measured by GPC was 350,000, the melting point was 141°C, and the crystallization temperature (Tc) was 80°C.

The crystallization temperature (Tc) and melting point were measured by differential scanning calorimetry (DSC). As an apparatus, an EXSTAR6000 series DSC6200 manufactured by Hitachi Hightex Science was used. 5 to 10 mg of P3HB3HH was placed in an aluminum pan, which was covered and crimped to obtain a measurement sample. The temperature was raised from 25° C. to 180° C. at a rate of 10° C./min and then lowered to 25° C. at a rate of 10° C./min. Nitrogen gas was flowed at 50 mL/min during the measurement. The endothermic peak observed in the temperature rising process was taken as the melting peak, and the peak top temperature was taken as the melting point. An exothermic peak observed in the temperature-lowering process was defined as a crystallization peak, and the peak top temperature was defined as a crystallization temperature (Tc).

<Examples 1 to 11, Comparative Examples 1 to 3>
To P3HB3HH (100 parts by weight) obtained in Production Example 1, 3 parts by weight of pentaerythritol (Neuilizer P manufactured by Nippon Synthetic Chemical Co., Ltd.) as a crystal nucleating agent and erucamide (Nippon Seika Co., Ltd.) as a lubricant are added. 5 parts by weight of Nutron S manufactured by Toshiba Machine Co., Ltd. and 0.5 parts by weight of behenic acid amide (behenic acid amide, BNT-22H manufactured by Nippon Seika Co., Ltd.), which is a lubricant, are dry-blended. The mixture was melt-kneaded at 130 to 160° C. using an extruder (TEM26SS) and pelletized. The obtained pellets are melted in a single-screw extruder with a screw diameter of 20 mm, and the flow rate is adjusted with a gear pump. is extruded from a spinning die having 815 at the discharge rate shown in Tables 1 and 2, cooled with a cooling air flow at 25 ° C., stretched at the pressure shown in Tables 1 and 2 with an ejector, and moved on a conveyor deposited on top to form a web. Thereafter, this web was subsequently partially heat-bonded at the line speeds and pressure heat-bonding roll temperatures shown in Tables 1 and 2.
FIG. 1 shows a schematic diagram of the apparatus used for the production of the nonwoven fabric described above.

(Examples 12-13)
To the P3HB3HH (100 parts by weight) obtained in Production Example 1, 1.5 parts by weight of pentaerythritol (Neurizer P manufactured by Nippon Synthetic Chemical Co., Ltd.) as a crystal nucleating agent and erucic acid amide (Nippon Seisaku Co., Ltd.) as a lubricant are added. Chemical Co., Ltd. Neutron S) 0.5 parts by weight and lubricant behenic acid amide (behenic acid amide, Nippon Seika Co., Ltd. BNT-22H) 0.5 parts by weight are dry blended, Toshiba Machine Co., Ltd. The mixture was melt-kneaded at 130 to 160° C. using a twin-screw extruder (TEM26SS) manufactured by the company and pelletized. The obtained 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 as shown in Table 1, at a melt spinning temperature of 170 ° C., 815 spinning holes with a diameter of 0.3 mm It is extruded from an individual spinning die at the discharge rate shown in the table, cooled using a cooling air flow at 25° C., stretched with an ejector at the pressure shown in Table 1, and deposited on a moving conveyor to form a web. formed. This web was then subsequently partially heat bonded at the line speed and pressure heat bond roll temperature shown in Table 1.
FIG. 1 shows a schematic diagram of the apparatus used for the production of the nonwoven fabric described above.

(Moldability of nonwoven fabric)
In the examples and comparative examples, the shrinkage of the web on the conveyor and the state of sticking to the pressure heat bonding roll were visually evaluated to evaluate the formability of the nonwoven fabric (whether or not the nonwoven fabric can be formed) according to the following criteria.
A (Extremely good formability): Nonwoven fabric can be removed without shrinkage on the conveyor and sticking to the pressurized heat bonding roll.
B (Good formability): The nonwoven fabric is removed without sticking to the pressurized heat bonding roll, although it shrinks a little on the conveyor.
C (Poor formability): The nonwoven fabric shrinks on the conveyor and sticks to the pressurized heat bonding roll, so that the nonwoven fabric cannot be removed.

(Tensile elongation, tensile strength, tear strength of nonwoven fabric)
Based on JIS L 1096, the obtained nonwoven fabric was cut into 5 × 30 cm test pieces in the MD direction (the direction in which the nonwoven fabric flows) and the CD direction (the direction in which the nonwoven fabric flows perpendicular to the flow). (manufactured by AUTOGRAPH AG2000A)), the breaking elongation and breaking strength were measured five times at a test speed of 100 mm/min, and the averaged values were taken as the tensile elongation and tensile strength. Moreover, based on the same standard, the tear strength was measured by the single tongue method. A 10 cm cut was made in the center of the short side of the test piece of the same size, and the tear strength was measured five times at a tensile speed of 200 cm/min, and the average value was taken as the tear strength.

(Thread diameter and basis weight of non-woven fabric)
Based on JIS L 1096, the obtained nonwoven fabric was cut into a test piece of 25×20 cm, the weight was measured, and the weight per area was measured five times, and the averaged value was used as the basis weight. The nonwoven fabric was observed with an optical microscope to measure the fiber diameter (thread diameter).

As can be seen from Table 1, in Examples, the nonwoven fabrics containing P3HA had good moldability, and nonwoven fabrics essentially containing only P3HA as the resin component could be produced with good moldability.

On the other hand, as can be seen from Table 2, in Comparative Examples 1 and 3, in which the pressure and heat bonding treatment temperature in step C is less than Tc-45°C, crystallization is insufficient because the temperature of the pressure and heat bonding roll is low. , the nonwoven fabric adhered to the pressurized heat bonding roll, and the nonwoven fabric could not be obtained. In Comparative Example 2, in which the pressure and heat bonding treatment temperature in step C is higher than Tc + 5 ° C., the temperature of the pressure and heat bonding roll is high, so the resin softens and the nonwoven fabric adheres to the pressure and heat bonding roll. could not get

a Fiber b Web c Nonwoven fabric 1 Spinneret 2 Quencher 3 Ejector 4 Conveyor 5 Temporary fixing roll 6 Pressurized heat bonding roll 7 Winding roll

Claims (11)

a step A of melt-spinning a composition containing poly(3-hydroxyalkanoate) using a spinneret to obtain a fiber;
A step B of forming a web from the fibers obtained in step A to obtain a web;
and a step C of subjecting the web obtained in step B to pressure heat bonding,
A nonwoven fabric characterized in that the pressure heat bonding treatment temperature in the step C is (Tc-45) ° C. or higher and (Tc + 5) ° C. or lower [Tc: crystallization temperature of poly(3-hydroxyalkanoate)]. Production method. 2. The method for producing a nonwoven fabric according to claim 1, wherein the temperature for the pressurized thermal bonding treatment is (Tc-40)° C. or higher and (Tc+0)° C. or lower. 3. The method for producing a nonwoven fabric according to claim 1 or 2, wherein the amount of the composition discharged per single hole from the spinneret in step A is 0.2 to 1.2 g/min. 4. The method for producing a nonwoven fabric according to claim 3, wherein the amount of the composition discharged per single hole from the spinneret in step A is 0.2 to 0.7 g/min. 5. The method for producing a nonwoven fabric according to any one of claims 1 to 4, wherein the web formation in step B is performed by a spunbond method. The method for producing a nonwoven fabric according to any one of claims 1 to 5, wherein the melt spinning temperature in step A is 145 to 190°C. The method for producing a nonwoven fabric according to any one of claims 1 to 6, wherein the composition further contains a crystal nucleating agent. The method for producing a nonwoven fabric according to claim 7, wherein the content of the crystal nucleating agent is 0.05 to 12 parts by weight per 100 parts by weight of poly(3-hydroxyalkanoate). The method for producing a nonwoven fabric according to any one of claims 1 to 8, wherein the composition further contains a lubricant. 10. The method for producing a nonwoven fabric according to claim 9, wherein the content of said lubricant is 0.05 to 12 parts by weight per 100 parts by weight of poly(3-hydroxyalkanoate). The poly(3-hydroxyalkanoate) is poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxy hexanoate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), which is at least one selected from the group consisting of any one of claims 1 to 10 A method for producing the nonwoven fabric according to item 1.

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