Nonwoven fabric, layered sheet including same, and product for use with food including said nonwoven fabric and layered sheet

Abstract

The present invention relates to a non-woven fabric, including cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers that contain a poly(3-hydroxyalkanoate)-based resin, wherein the poly(3-hydroxyalkanoate)-based fiber is in compliance with JIS K 7210-1, has a melt flow rate, measured at a temperature of 160°C and a load of 5 kg (49 N), of at least 35 g / 10 minutes and no greater than 90 g / 10 minutes, and has a cellulose-based fiber content of at least 30% by mass and less than 70% by mass with respect to the total mass of the cellulose-based fibers and the poly(3-hydroxyalkanoate)-based fibers. Due to the foregoing, provided are: a non-woven fabric that has good heat-sealing properties; a layered sheet that includes the non-woven fabric; and a product for use with food that includes the non-woven fabric and the layered sheet.

Description

Nonwoven fabric, laminated sheet containing the same, and food product containing the same

[0001] The present invention relates to a biodegradable nonwoven fabric, a laminated sheet containing the same, and a food product containing either of them.

[0002] Plastics are an indispensable resource in modern daily life, widely used in industrial materials such as packaging and containers. However, plastic waste is often incinerated, which generates harmful gases during incineration, thereby placing a significant burden on the global environment, including impacting ecosystems and contributing to global warming due to the large amount of heat generated by combustion. This has become a global problem. As one solution, biodegradable plastics have been used in a wide range of fields. For example, Patent Document 1 describes a biodegradable staple fiber nonwoven fabric containing cellulose-based staple fiber A and staple fiber B containing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0003] JP 2022-114186 A

[0004] On the other hand, strength and heat sealability are often required for nonwoven fabrics used in containers for foods such as beverages, filters, etc. However, the heat sealability of the nonwoven fabric described in Patent Document 1 was not considered, and there was room for improvement in terms of heat sealability.

[0005] In order to solve the above-mentioned problems of the prior art, the present invention provides a nonwoven fabric having good heat-sealability, a laminated sheet containing the same, and a food product containing them.

[0006] One or more embodiments of the present invention relate to a nonwoven fabric comprising a cellulose-based fiber and a poly(3-hydroxyalkanoate)-based fiber containing a poly(3-hydroxyalkanoate)-based resin, wherein the poly(3-hydroxyalkanoate)-based fiber has a melt flow rate of 35 g / 10 min or more and 90 g / 10 min or less, measured in accordance with JIS K 7210-1 at a temperature of 160°C and a load of 5 kg (49 N), and the content of the cellulose-based fiber is 30 mass% or more and less than 70 mass% of the total mass of the cellulose-based fiber and the poly(3-hydroxyalkanoate)-based fiber.

[0007] One or more embodiments of the present invention relate to a laminate sheet including a layer containing the nonwoven fabric and a layer containing nonwoven fabric II, wherein the nonwoven fabric II contains cellulosic fibers and poly(3-hydroxyalkanoate)-based fibers that contain a poly(3-hydroxyalkanoate)-based resin, and the content of the cellulosic fibers in the nonwoven fabric II is 70% by mass or more and 100% by mass or less, relative to the total mass of the cellulosic fibers and the poly(3-hydroxyalkanoate)-based fibers.

[0008] One or more embodiments of the present invention relate to food-grade products comprising the nonwoven fabric.

[0009] One or more embodiments of the present invention relate to a food product comprising the laminate sheet.

[0010] The present invention can provide a nonwoven fabric having good heat-sealing properties, a laminated sheet containing the nonwoven fabric, and a food product containing the nonwoven fabric or the laminated sheet.

[0011] The present inventors conducted extensive research to solve the above-mentioned problems and found that, in a nonwoven fabric containing cellulose fibers and poly(3-hydroxyalkanoate) fibers containing a poly(3-hydroxyalkanoate) resin, the heat sealability of the nonwoven fabric at temperatures of 170°C or higher can be significantly improved by controlling the melt flow rate (hereinafter also referred to as MFR) of the poly(3-hydroxyalkanoate) fibers, measured in accordance with JIS K 7210-1 at a temperature of 160°C and a load of 5 kg (49 N), within a specific range, and controlling the blending amounts of the cellulose fibers and the poly(3-hydroxyalkanoate) fibers within specific ranges.

[0012] Specifically, the inventors have found that a nonwoven fabric (hereinafter also referred to as "nonwoven fabric I") containing cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, the poly(3-hydroxyalkanoate)-based fibers having an MFR of 35 g / 10 min or more and 90 g / 10 min or less, and containing 30% by mass or more but less than 70% by mass of the cellulose-based fibers relative to the total mass of the cellulose-based fibers and the poly(3-hydroxyalkanoate)-based fibers, exhibits significantly improved heat-sealability at temperatures of 170°C or higher. Specifically, the nonwoven fabric exhibits good adhesive strength and good peeling properties at heat-sealed portions at temperatures of 170°C or higher.

[0013] Hereinafter, poly(3-hydroxyalkanoate) resin will also be referred to as P3HA, and poly(3-hydroxyalkanoate) fiber will also be referred to as P3HA fiber. Furthermore, hereinafter, unless otherwise specified, MFR refers to the melt flow rate measured in accordance with JIS K 7210-1 under conditions of a temperature of 160°C and a load of 5 kg (49 N).

[0014] [Poly(3-hydroxyalkanoate)-Based Fibers] In one or more embodiments of the present invention, the poly(3-hydroxyalkanoate)-based fibers contain P3HA, preferably 80% by mass or more of P3HA, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. In one or more embodiments of the present invention, the P3HA-based fibers may be composed of 100% by mass of P3HA, if desired.

[0015] When the MFR of the P3HA fiber is 35 g / 10 min or more and 90 g / 10 min or less, the fluidity of the P3HA fiber falls within an appropriate range, which tends to improve the adhesive strength (hereinafter also referred to as heel sheet strength) of heat-sealed portions between nonwoven fabrics I containing the P3HA fiber and cellulose fiber, or between nonwoven fabric I and other materials, such as graft paper. The MFR of the P3HA fiber is preferably 38 g / 10 min or more, more preferably 40 g / 10 min or more, even more preferably 45 g / 10 min or more, and even more preferably 50 g / 10 min or more.

[0016] The mass average molecular weight (Mw) of the P3HA fiber is not particularly limited. However, from the viewpoint of fiber productivity and heat sealability of the nonwoven fabric, it is preferably 100,000 or more but less than 300,000, more preferably 120,000 or more but less than 290,000, even more preferably 140,000 or more but less than 280,000, and even more preferably 150,000 or more but less than 260,000. In this specification, the mass average molecular weight refers to a molecular weight distribution measured in terms of polystyrene using gel permeation chromatography (GPC) with a chloroform eluent. A column suitable for measuring the molecular weight may be used for the GPC.

[0017] The melting point of the P3HA fiber is not particularly limited, but from the viewpoint of stabilizing fiber production, it is preferably from 145° C. to 180° C., more preferably from 150° C. to 180° C., and even more preferably from 155° C. to 180° C. In this specification, the melting point can be measured as described in the examples.

[0018] The single fiber fineness of the P3HA fiber is not particularly limited, but from the viewpoint of nonwoven fabric quality, it is preferably 0.1 dtex or more and 100 dtex or less, more preferably 0.5 dtex or more and 50 dtex or less, even more preferably 1.0 dtex or more and 25 dtex or less, and even more preferably 1.0 dtex or more and 5 dtex or less. In this specification, the single fiber fineness of the P3HA fiber can be measured as described in the Examples.

[0019] The P3HA fibers may be long fibers (drawn filaments) or short fibers. When nonwoven fabric I is a short fiber nonwoven fabric, the fiber length of the P3HA fibers may be 1 mm or more and 176 mm or less, 2 mm or more and 138 mm or less, or 3 mm or more and 110 mm or less. When nonwoven fabric I is a wetlaid nonwoven fabric, from the viewpoint of dispersibility in water, the fiber length of the P3HA fibers may be 1 mm or more and 20 mm or less, 2 mm or more and 15 mm or less, or 3 mm or more and 12 mm or less.

[0020] The tensile strength of the P3HA fiber is not particularly limited, but from the viewpoints of mechanical strength and practicality, it is preferably 0.3 cN / dtex to 6.0 cN / dtex, more preferably 0.5 cN / dtex to 5.0 cN / dtex, and even more preferably 0.8 cN / dtex to 4.0 cN / dtex. In this specification, the tensile strength of the P3HA fiber can be measured as described in the Examples.

[0021] The breaking elongation of the P3HA fiber is not particularly limited, but from the viewpoint of practicality, it is preferably 10% or more and 150% or less, more preferably 20% or more and 140% or less, and even more preferably 30% or more and 130% or less. In this specification, the breaking elongation of the P3HA fiber can be measured as described in the examples.

[0022] The initial elastic modulus of the P3HA fiber is not particularly limited, but from the viewpoint of stable production of nonwoven fabrics, it is preferably 0.1 GPa or more and 5.0 GPa or less, more preferably 0.2 GPa or more and 3.0 GPa or less, and even more preferably 0.4 GPa or more and 2.0 GPa or less. In this specification, the initial elastic modulus of the P3HA fiber can be measured as described in the Examples.

[0023] P3HA can be a resin having a 3-hydroxyalkanoate unit. Specific examples of the 3-hydroxyalkanoate unit include those represented by the following general formula (1):

[0024]

[0025] However, in the general formula (1), R 1 represents an alkyl group having 1 to 15 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 8 carbon atoms. 1 Specific examples of the alkyl group include linear or branched alkyl groups such as methyl, ethyl, propyl, methylpropyl, butyl, isobutyl, t-butyl, pentyl, and hexyl.

[0026] P3HA preferably contains 3-hydroxyalkanoate units in an amount of 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, or may consist of 100 mol%.

[0027] From the viewpoint of excellent marine degradability, P3HA preferably contains 50 mol% or more of 3-hydroxybutyrate (hereinafter also referred to simply as "3HB") units relative to all monomer units (100 mol%), more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, and may even consist of 100 mol%. That is, P3HA may be a homopolymer consisting of only 3-hydroxybutyrate units, or a copolymer consisting of 3-hydroxybutyrate units (b1) and other hydroxyalkanoate units (b2) (hereinafter also referred to as P3HB-based copolymer).

[0028] Examples of the other hydroxyalkanoate units (b2) include 3-hydroxyalkanoate units other than 3-hydroxybutyrate units, and 4-hydroxyalkanoate units. More specific examples include 3-hydroxyvalerate units, 3-hydroxyhexanoate (hereinafter also simply referred to as "3HH") units, 3-hydroxyoctanoate units, and 4-hydroxybutyrate units. The other hydroxyalkanoate units (b2) may be of one type or two or more types.

[0029] From the viewpoint of the balance between flexibility and strength, the P3HB copolymer preferably contains more than 24 mol% and 99 mol% or less of 3-hydroxybutyrate units (b1), and more preferably 25 mol% or more and 98 mol% or less of 3-hydroxybutyrate units (b1), relative to the total 100 mol% of 3-hydroxybutyrate units (b1) and other hydroxyalkanoate units (b2). From the viewpoint of mechanical properties, the P3HB copolymer is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter also referred to as "P3HB3HH") and / or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and more preferably P3HB3HH.

[0030] P3HA can be produced by any known method without any particular limitation, but from the viewpoint of easily obtaining P3HA with high marine degradability, it is preferable to produce it by a production method using a microorganism. Any known method can be used for the production method using a microorganism. The microorganism is not particularly limited as long as it has the ability to produce P3HA. Examples of microorganisms capable of producing P3HA include Aeromonas caviae, Cupriavidus necator, Ralstonia eutropha, and Alcaligenes latus. Furthermore, in order to increase the productivity of P3HA, Alcaligenes eutrophus AC32 strain (FERM BP-6038) (J. Bateriol., 179, pp. 4821-4830 (1997)) into which genes encoding poly(3-hydroxyalkanoate) synthases have been introduced may be used. Furthermore, commercially available P3HA products such as the biodegradable polymer Green Planet (registered trademark) manufactured by Kaneka Corporation may also be used.

[0031] The MFR of P3HA is not particularly limited as long as the MFR of the P3HA-based fiber satisfies the above-mentioned range, but for example, it is preferably 0.1 g / 10 min to 100 g / 10 min, more preferably 1 g / 10 min to 50 g / 10 min, and even more preferably 10 g / 10 min to 40 g / 10 min. When the MFR of the P3HA used as a raw material is within the above-mentioned range, the fluidity of the molten resin becomes an appropriate range, and fiberization becomes good.

[0032] The mass average molecular weight of P3HA is not particularly limited, but may be 50,000 or more and 1,000,000 or less, or 100,000 or more and 500,000 or less, from the viewpoint that the mass average molecular weight of the P3HA-based fiber is likely to fall within the above-mentioned preferred range.

[0033] The melting point of P3HA is not particularly limited, but from the viewpoint of stabilizing fiber production, it is preferably 145°C or higher and 180°C or lower, and more preferably 150°C or higher and 180°C or lower.

[0034] In addition to P3HA, the P3HA-based fiber preferably further contains a nucleating agent from the viewpoints of productivity and fiber properties. The nucleating agent is not particularly limited as long as it is a compound that has the effect of promoting the crystallization of P3HA. For example, from the viewpoint of improving the crystallization rate and being contained in the fiber, the nucleating agent is preferably a sugar alcohol compound, polyvinyl alcohol, chitin, chitosan, etc., more preferably a sugar alcohol compound, and even more preferably pentaerythritol. One type of nucleating agent may be used alone, or two or more types may be used in combination.

[0035] In P3HA-based fibers, the content of the nucleating agent is not particularly limited, but from the viewpoint of productivity and fiber properties, it is, for example, preferably from 0.05 parts by mass to 12 parts by mass, more preferably from 0.1 parts by mass to 10 parts by mass, even more preferably from 0.5 parts by mass to 8 parts by mass, and particularly preferably from 1 part by mass to 5 parts by mass, per 100 parts by mass of P3HA.

[0036] From the viewpoint of productivity, it is preferable that the P3HA-based fiber further contains a lubricant. The lubricant is not particularly limited as long as it is a compound that has the effect of imparting lubricity to the P3HA. Examples of the lubricant include fatty acid amides, alkylene fatty acid amides, glycerin monofatty acid esters, organic acid monoglycerides, sorbitan fatty acid esters, polyglycerin fatty acid esters, and higher alcohol fatty acid esters.

[0037] Among the above-mentioned lubricants, compounds having the effect of imparting external lubrication, specifically fatty acid amides and glycerin fatty acid esters, are particularly preferred. Examples of fatty acid amides include fatty acid monoamides and bisamides. The fatty acid (fatty acid moiety) constituting the fatty acid amide preferably has 12 to 30 carbon atoms, more preferably 18 to 22 carbon atoms, from the viewpoint of providing a resin composition with a moderately high melting point and preventing a decrease in processability during melt processing. Specific examples of fatty acid amides include behenamide, erucamide, palmitamide, oleamide, stearamide, methylenebisstearamide, ethylenebisstearamide, ethylenebisoleamide, and ethylenebiserucamide. Examples of glycerin fatty acid esters include glycerin monoesters, glycerin diesters, and glycerin triesters (e.g., glycerin diacetomonoesters such as glycerin diacetomonolaurate, glycerin diacetomonooleate, glycerin diacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate). These may be used alone or in combination of two or more.

[0038] In P3HA-based fibers, the content of the lubricant is not particularly limited, but is preferably 0.05 parts by mass or more and 12 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less, even more preferably 0.5 parts by mass or more and 8 parts by mass or less, and particularly preferably 1 part by mass or more and 5 parts by mass or less, per 100 parts by mass of P3HA.

[0039] The P3HA-based fiber may contain, as necessary, other resin components in addition to P3HA, as long as the effects of the present invention are not impaired. The other resin components are preferably biodegradable resins. The content of the other resin components may be 20 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less per 100 parts by mass of P3HA. The other resin components may be used alone or in combination of two or more.

[0040] The P3HA-based fiber may optionally contain other additive components such as plasticizers, inorganic fillers, organic fillers (e.g., cellulose), antioxidants, ultraviolet absorbers, colorants such as dyes and pigments, and antistatic agents, within the range that does not impair the effects of the present invention. The content of the other additive components may be 5 parts by mass or less, 3 parts by mass or less, or 1 part by mass or less per 100 parts by mass of P3HA.

[0041] The P3HA-based fibers can be obtained, for example, by fiberizing a resin composition containing P3HA, preferably P3HA, a crystal nucleating agent, and a lubricant.

[0042] The resin composition is not particularly limited, but preferably contains 80% by mass or more of P3HA, more preferably 85% by mass or more, and even more preferably 90% by mass or more. Meanwhile, the upper limit of the P3HA content in the resin composition may be 100% by mass, but may be, for example, 98% by mass or less or 95% by mass or less. By setting the P3HA content to 80% by mass or more, the biodegradability of the nonwoven fabric I tends to be further improved. The nucleating agent and lubricant described above can be used as appropriate. The amounts of the nucleating agent and lubricant used can also be determined appropriately depending on the content of the nucleating agent and lubricant in the P3HA-based fiber.

[0043] The resin composition may contain other resin components and additive components as needed, as long as the effects of the present invention are not impaired. The amounts of the other resin components and additive components used in the resin composition can be determined appropriately depending on the contents of the other resin components and additive components in the P3HA-based fiber.

[0044] The MFR of the resin composition is not particularly limited as long as the MFR of the P3HA fiber satisfies the above-mentioned range, but is preferably 0.1 g / 10 min or more and 100 g / 10 min or less, more preferably 1 g / 10 min or more and 50 g / 10 min or less, and even more preferably 10 g / 10 min or more and 40 g / 10 min or less. When the MFR of the resin composition is within the above-mentioned range, the fluidity of the molten resin becomes an appropriate range, and fiberization becomes good.

[0045] The mass average molecular weight of the resin composition is not particularly limited, but may be 50,000 or more and 1,000,000 or less, or 100,000 or more and 500,000 or less, from the viewpoint that the mass average molecular weight of the P3HA-based fiber is likely to fall within the above-mentioned preferred range.

[0046] The melting point of the resin composition is not particularly limited, but is preferably 145°C or higher and 180°C or lower, and more preferably 150°C or higher and 180°C or lower, from the viewpoint of stabilizing fiber production.

[0047] More specifically, P3HA-based fibers can be obtained by melt spinning the resin composition. First, the pellet-shaped resin composition obtained by melt-kneading the resin composition is melted using a melt extruder and continuously extruded from a spinning nozzle (also called a spinneret) to form fibers, thereby producing undrawn filaments. The melt-kneading and melt-spinning temperatures are not particularly limited as long as they are equal to or higher than the melting point and lower than the thermal decomposition temperature of the resin composition. For example, when the melting point of the resin composition is Tmc, it is preferably [Tmc + 3 ° C] or higher [Tmc + 18 ° C] or lower, and more preferably [Tmc + 5 ° C] or higher [Tmc + 15 ° C] or lower. By setting the melt-kneading and melt-spinning temperatures within the above-mentioned ranges, spinning is easily stabilized, the physical properties of the obtained fiber tend to be further improved, and the MFR of the P3HA-based fiber is more likely to satisfy the above-mentioned range. Note that the melt-spinning temperature refers to the highest temperature range among the temperatures applied during the fiberization of the resin composition.

[0048] The ambient temperature during extrusion from the spinneret is not particularly limited and can be adjusted as appropriate, for example, within the range of 5°C to 40°C. It is preferable to apply rectified air to the fibers (undrawn filaments) extruded from the spinneret. The rectified air is also called quench air and serves to stabilize the flow of the yarn. It is also possible to cool the spun filaments by using cooled gas as quench air. The temperature of the quench air is preferably 5°C to 40°C, more preferably 10°C to 30°C. A temperature of 5°C or higher tends to prevent residual stress from occurring in the fibers. A temperature of 40°C or lower allows sufficient solidification of the resin, making it easy to prevent the fibers from sticking together. The wind speed of the quench air is not particularly limited, but is preferably, for example, 0.1 m / s to 3.0 m / s. When the speed is 0.1 m / sec or more, the effect of straightening the flow is easily exhibited, and when the speed is 3.0 m / sec or less, the quench air is not too strong, the yarn is not disturbed, and sticking of the fibers together and yarn breakage are suppressed.

[0049] Next, the undrawn filament is drawn to obtain a drawn filament (multifilament). Drawing not only allows for the production of a fiber with the desired fineness, but also increases the fiber strength. The drawing method is not particularly limited, and may be a two-stage spinning / drawing method or a direct spinning / drawing method. In the two-stage spinning / drawing method, drawing is performed after the spun filament is wound. In the direct spinning / drawing method, spinning and drawing are performed continuously without winding the spun filament. The drawing process may also be performed in multiple stages, such as by combining multiple roll pairs. The surface temperatures and speeds of the multiple rolls may be the same or different. The drawing temperature, specifically the roll surface temperature, is not particularly limited, but may be, for example, 30°C or higher and 100°C or lower, or 40°C or higher and 90°C or lower. The draw ratio may be, for example, 1.5 times or higher and 20 times or lower. A draw ratio of 1.5 times or higher can further increase the fiber strength. If necessary, after drawing, the filaments may be subjected to heat relaxation at a temperature of 80°C to 100°C at a relaxation rate of 1% to 20%. Before drawing, an oil may be applied to the undrawn filaments as necessary. Known oils for synthetic fibers may be used as the oil.

[0050] The tensile strength of the drawn filament is preferably 0.3 cN / dtex or more and 6.0 cN / dtex or less, more preferably 0.5 cN / dtex or more and 5.0 cN / dtex or less, and even more preferably 1.0 cN / dtex or more and 4.0 cN / dtex or less.

[0051] The drawn filaments may be used as they are as long P3HA fibers, or may be cut to a predetermined fiber length and used as short P3HA fibers.

[0052] (Cellulosic Fibers) The cellulose fibers are not particularly limited, and may be natural cellulose fibers or regenerated cellulose fibers.

[0053] The natural cellulose fibers may be of plant or animal origin. Examples of plant-derived fibers include plant-derived pulp. Examples of pulp include those obtained by pulping plant materials chemically, mechanically, or by a combination of both. Examples of plant-derived fibers include wood, cotton, bamboo, hemp, shoots, and kenaf. The pulp may also be recycled pulp obtained from waste paper or the like. The average fiber length of the pulp is not particularly limited, but when the nonwoven fabric I is a wet-laid nonwoven fabric, it may be 1 mm to 20 mm, 2 mm to 15 mm, or 3 mm to 12 mm in terms of water dispersibility. The average fiber diameter of the pulp is not particularly limited, but may be 7 μm to 20 μm, or 10 μm to 18 μm in terms of miscibility with P3HA-based fibers.

[0054] Examples of regenerated cellulose fibers include rayon, polynosic, cupra, and lyocell. The fiber length of the regenerated cellulose fibers is not particularly limited, but when the nonwoven fabric I is a staple fiber nonwoven fabric, it may be 1 mm to 176 mm, 2 mm to 138 mm, or 3 mm to 110 mm. When the nonwoven fabric I is a wet-laid nonwoven fabric, from the viewpoint of water dispersibility, the fiber length of the regenerated cellulose fibers may be 1 mm to 20 mm, 2 mm to 15 mm, or 3 mm to 12 mm.

[0055] The regenerated cellulose fibers are not particularly limited, but from the viewpoint of excellent miscibility with P3HA-based fibers, for example, the single fiber fineness is preferably 0.1 dtex or more and 100 dtex or less, more preferably 0.5 dtex or more and 50 dtex or less, even more preferably 1.0 dtex or more and 25 dtex or less, and even more preferably 1.0 dtex or more and 15 dtex or less.

[0056] (Nonwoven fabric) Nonwoven fabric I contains P3HA fibers and cellulose fibers, and the content of cellulose fibers is 30% by mass or more and less than 70% by mass, and the content of P3HA fibers is more than 30% by mass and 70% by mass or less, relative to the total mass of the P3HA fibers and cellulose fibers. This provides nonwoven fabric I with good heat sealability and excellent physical properties such as tensile strength. In nonwoven fabric I, the content of cellulose fibers is preferably 35% by mass or more and 65% by mass, and the content of P3HA fibers is preferably 35% by mass or more and 65% by mass or less, relative to the total mass of the P3HA fibers and cellulose fibers. As the P3HA fibers and cellulose fibers, those described above are used as appropriate.

[0057] From the viewpoint of biodegradability, nonwoven fabric I preferably contains the P3HA-based fibers and the cellulose-based fibers in a total amount of 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. Nonwoven fabric I may contain other biodegradable fibers in addition to the P3HA-based fibers and the cellulose-based fibers, as long as the effects of the present invention are not impaired. Nonwoven fabric I may contain 20% by mass or less, 10% by mass or less, or 5% by mass or less of the other biodegradable fibers.

[0058] From the viewpoints of heat-sealing properties and strength, nonwoven fabric I is preferably a mixed fiber nonwoven fabric. Furthermore, from the viewpoint of cost, nonwoven fabric I is preferably a staple fiber nonwoven fabric. Depending on the intended use, nonwoven fabric I may be a dry-laid or wet-laid nonwoven fabric. When used in food products, nonwoven fabric I is preferably a wet-laid nonwoven fabric.

[0059] The method for producing nonwoven fabric I is not particularly limited, and can include a web-forming process and an interfiber bonding process, similar to the process for producing a general nonwoven fabric. In the web-forming process, the mixing ratio of the P3HA fiber and the cellulose fiber is set to satisfy the content ratio of the P3HA fiber and the cellulose fiber in nonwoven fabric I, and in the interfiber bonding process, the fibers can be thermally bonded with a samar bond, specifically, the P3HA fiber. When nonwoven fabric I is a wetlaid nonwoven fabric, the wetlaid nonwoven fabric can be produced, for example, by a wetlaid papermaking method as described below.

[0060] First, the above-mentioned P3HA fiber and cellulose fiber (e.g., pulp) are mixed, the mixed fiber is dispersed in water, and the resulting fiber slurry is paper-made to obtain a wet sheet (wet fiber web). The concentration of the mixed fiber in the fiber slurry is not particularly limited, but from the viewpoint of water dispersibility, it is preferably 0.01% by mass or more and 0.5% by mass or less. The mixing ratio of the P3HA fiber and cellulose fiber in the mixed fiber may be determined so that the content of the P3HA fiber and cellulose fiber in the nonwoven fabric I falls within the above-mentioned range. For papermaking, for example, a cylinder wire paper machine, a long wire paper machine, a short wire paper machine, an inclined short wire paper machine, or a combination inclined short wire, cylinder wire, and former type paper machine can be appropriately used. When dispersing the mixed fiber in water, a dispersant or a dispersion aid may be used as needed.

[0061] Next, the obtained wet sheet is dried in a dryer to bond the fibers together, thereby obtaining a wetlaid nonwoven fabric (mixed fiber nonwoven fabric). As the dryer, a dryer generally used in wet papermaking methods, such as a Yankee dryer, can be used as appropriate. The drying temperature (for example, the temperature of the heat roll) is not particularly limited as long as it can bond the fibers together. For example, from the viewpoint of stable production, when the melting point of the P3HA fiber is Tmf, it is preferably [Tmf - 40°C] or more and [Tmf - 25°C] or less.

[0062] The basis weight of the nonwoven fabric I is not particularly limited and may be determined appropriately depending on the application, purpose, etc. For example, when used for food products such as food filters and food packaging materials, the basis weight of the nonwoven fabric I is preferably 10 g / m 2 More than 100g / m 2Below, 15g / m 2 85g / m or more 2 or less than 20 g / m 2 80g / m or more 2 In this specification, the basis weight of a nonwoven fabric can be measured as described in the examples.

[0063] The thickness of the nonwoven fabric I is not particularly limited and may be determined appropriately depending on the application, purpose, etc. For example, when used in food products such as food filters and food packaging materials, the thickness of the nonwoven fabric I may preferably be 0.03 mm or more and 0.2 mm or less, 0.045 mm or more and 0.19 mm or less, or 0.06 mm or more and 0.18 mm or less. In this specification, the thickness of the nonwoven fabric can be measured as described in the examples.

[0064] The density of the nonwoven fabric I is not particularly limited and may be determined appropriately depending on the application, purpose, etc. For example, when used in food products such as food filters and food packaging materials, the density of the nonwoven fabric I is preferably 0.1 g / cm 3 1.0g / cm or more 3 Below, 0.15g / cm 3 0.9g / cm or more 3 or less, or 0.2 g / cm 3 0.8g / cm or more 3 In this specification, the density of the nonwoven fabric can be measured as described in the examples.

[0065] The tensile strength of the nonwoven fabric I is not particularly limited and may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the tensile strength of the nonwoven fabric I in the machine direction (MD) is preferably 1.0 N / 15 mm to 50 N / 15 mm, 1.5 N / 15 mm to 40 N / 15 mm, or 2.0 N / 15 mm to 30 N / 15 mm. Furthermore, when used in food products such as food filters and food packaging materials, the tensile strength of the nonwoven fabric I in the cross direction (CD) is preferably 1.0 N / 15 mm to 30 N / 15 mm, 1.5 N / 15 mm to 25 N / 15 mm, or 2.0 N / 15 mm to 20 N / 15 mm. In this specification, the tensile strength of the nonwoven fabric can be measured as described in the examples.

[0066] The breaking elongation of the nonwoven fabric I is not particularly limited, but may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the breaking elongation of the nonwoven fabric I in the machine direction (MD) may preferably be 0.5% to 10%, 1.0% to 8.0%, or 2.0% to 5.0%. Furthermore, when used in food products such as food filters and food packaging materials, the breaking elongation of the nonwoven fabric I in the cross direction (CD) may preferably be 0.5% to 10%, 1.0% to 8.0%, or 2.0% to 5.0%. In this specification, the breaking elongation of the nonwoven fabric can be measured as described in the examples.

[0067] The heat seal strength between the nonwoven fabrics I is not particularly limited and may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the heat seal strength between the nonwoven fabrics I is preferably 1000 mN / 15 mm or more, more preferably 2000 mN / 15 mm or more, or 3000 mN / 15 mm or more, at temperatures in the range of 140°C to 240°C, 150°C to 240°C, or 150°C to 190°C, or any temperature within these ranges. Furthermore, when used in food products such as food filters and food packaging materials, it is preferable that the peeling mode of the heat-sealed adhesion between the nonwoven fabrics I is not substrate destruction at temperatures in the range of 170°C or more, 170°C to 240°C, or 170°C to 200°C, or any temperature within these ranges. If the peeling mode of the heat-sealed bond between the nonwoven fabrics I is substrate destruction, this means that the strength of the nonwoven fabric I after heat sealing is low and it cannot be used for heat-sealed products. In this specification, the heat-seal strength between the nonwoven fabrics and the peeling mode of the bond after heat sealing can be measured and evaluated as described in the examples.

[0068] The heat seal strength between the nonwoven fabric I and the kraft paper is not particularly limited and may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the heat seal strength between the nonwoven fabric I and the kraft paper is preferably 500 mN / 15 mm or more, more preferably 1000 mN / 15 mm or more, or 2000 mN / 15 mm or more, at temperatures in the range of 140°C to 240°C, 140°C to 200°C, 150°C to 200°C, 160°C to 200°C, 170°C to 200°C, or 170°C to 190°C, or any temperature within these ranges. In this specification, the heat seal strength between the nonwoven fabric and the kraft paper can be measured as described in the Examples.

[0069] (Laminated Sheet) In one or more embodiments of the present invention, the laminated sheet includes a layer including nonwoven fabric I and a layer including nonwoven fabric II. Similar to nonwoven fabric I, nonwoven fabric II also includes cellulosic fibers and P3HA fibers, except that the content of cellulosic fibers in nonwoven fabric II is different from the content of cellulosic fibers in nonwoven fabric I. As the cellulosic fibers and P3HA fibers, those described above can be used as appropriate.

[0070] In nonwoven fabric II, the content of cellulose-based fibers is 70% by mass or more and 100% by mass or less, preferably 80% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 100% by mass or less, based on the total mass of cellulose-based fibers and P3HA-based fibers.

[0071] From the viewpoint of biodegradability, nonwoven fabric II preferably contains a total of 80% by mass or more of P3HA-based fibers and cellulose-based fibers, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. Nonwoven fabric II may contain other biodegradable fibers in addition to the P3HA-based fibers and cellulose-based fibers, as long as the effects of the present invention are not impaired. Nonwoven fabric II may contain 20% by mass or less, 10% by mass or less, or 5% by mass or less of the other biodegradable fibers. Furthermore, nonwoven fabric II may be composed of 100% by mass of P3HA-based fibers and cellulose-based fibers, and the content of the cellulose-based fibers may be 100% by mass relative to the total mass of the cellulose-based fibers and P3HA-based fibers. That is, nonwoven fabric II may be composed solely of cellulose-based fibers, without including P3HA-based fibers.

[0072] Nonwoven fabric II may be a staple fiber nonwoven fabric or a wet-laid nonwoven fabric. When nonwoven fabric II is a wet-laid nonwoven fabric, the laminated sheet can be produced by a wet papermaking method. The wet papermaking can be performed in the same manner as the wet papermaking of nonwoven fabric I described above, except that the fiber slurry constituting nonwoven fabric I and the fiber slurry constituting nonwoven fabric II are laminated as two layers.

[0073] The basis weight of the laminated sheet is not particularly limited and may be determined appropriately depending on the application, purpose, etc. For example, when used for food products such as food filters and food packaging materials, the basis weight of the laminated sheet is preferably 10 g / m 2 More than 100g / m 2 Below, 15g / m 2 85g / m or more 2 or less than 20 g / m 2 80g / m or more 2 In the laminate sheet, the basis weight of nonwoven fabric I and the basis weight of nonwoven fabric II may be the same or different. In this specification, the basis weight of the laminate sheet can be measured as described in the examples.

[0074] The thickness of the laminate sheet is not particularly limited and may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the thickness of the laminate sheet may preferably be 0.03 mm or more and 0.2 mm or less, 0.045 mm or more and 0.19 mm or less, or 0.06 mm or more and 0.18 mm or less. In the laminate sheet, the thicknesses of nonwoven fabric I and nonwoven fabric II may be the same or different. In this specification, the thickness of the laminate sheet can be measured as described in the examples.

[0075] The density of the laminate sheet is not particularly limited and may be appropriately determined depending on the application, purpose, etc. For example, when used in food products such as food filters and food packaging materials, the density of the laminate sheet is preferably 0.1 g / cm 3 1.0g / cm or more 3 Below, 0.15g / cm 3 0.9g / cm or more 3 or less, or 0.2 g / cm 3 0.8g / cm or more 3 In the laminate sheet, the densities of nonwoven fabric I and nonwoven fabric II may be the same or different. In this specification, the density of the laminate sheet can be measured as described in the examples.

[0076] The tensile strength of the laminate sheet is not particularly limited and may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the tensile strength in the machine direction (MD) of the laminate sheet is preferably 5 N / 15 mm to 50 N / 15 mm, 10 N / 15 mm to 45 N / 15 mm, or 15 N / 15 mm to 40 N / 15 mm. Furthermore, when used in food products such as food filters and food packaging materials, the tensile strength in the cross direction (CD) of the laminate sheet is preferably 5 N / 15 mm to 30 N / 15 mm, 10 N / 15 mm to 25 N / 15 mm, or 14 N / 15 mm to 20 N / 15 mm. In this specification, the tensile strength of the laminate sheet can be measured as described in the examples.

[0077] The breaking elongation of the laminate sheet is not particularly limited, but may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the breaking elongation in the machine direction (MD) of the laminate sheet may preferably be 0.5% to 5.0%, 1.0% to 4.0%, or 1.5% to 3.0%. Furthermore, when used in food products such as food filters and food packaging materials, the breaking elongation in the cross direction (CD) of the laminate sheet may preferably be 0.5% to 5.0%, 1.0% to 4.5%, or 1.5% to 4.0%. In this specification, the breaking elongation of the laminate sheet can be measured as described in the examples.

[0078] The heat seal strength between the nonwoven fabrics I in the laminated sheets is not particularly limited, but may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the heat seal strength between the nonwoven fabrics I in the laminated sheets is preferably 500 mN / 15 mm or more, or even 1000 mN / 15 mm or more, or 1500 mN / 15 mm or more, at temperatures in the range of 140°C to 240°C, 150°C to 240°C, or 150°C to 190°C, or any temperature within these ranges. Furthermore, when used in food products such as food filters and food packaging materials, it is preferable that the peeling mode of the heat seal adhesion between the nonwoven fabrics I in the laminated sheets does not result in substrate destruction at temperatures in the range of 170°C or more, 170°C to 240°C, or 170°C to 200°C, or any temperature within these ranges. In this specification, the heat seal strength between the nonwoven fabrics I in the laminated sheets and the peeling state of the heat-sealed adhesion can be measured and evaluated as described in the Examples.

[0079] The heat seal strength between the nonwoven fabric I and the kraft paper in the laminate sheet is not particularly limited and may be determined appropriately depending on the application and purpose. For example, when used in food products such as food filters and food packaging materials, the heat seal strength between the nonwoven fabric I and the kraft paper in the laminate sheet is preferably 500 mN / 15 mm or more, or even 1000 mN / 15 mm or more, or 1400 mN / 15 mm or more, at temperatures in the range of 140°C to 240°C, 140°C to 200°C, 150°C to 200°C, 160°C to 200°C, 170°C to 200°C, or 170°C to 190°C, or any temperature within these ranges. In this specification, the heat seal strength between the nonwoven fabric I and the kraft paper in the laminate sheet can be measured as described in the Examples.

[0080] (Food Products) The nonwoven fabric I and the laminate sheet can be used for various materials such as industrial materials, household materials, and agricultural materials, and are particularly suitable for use in food products such as beverages that require heat-sealing properties. Food products are not particularly limited, but examples include food filters and food packaging materials. Examples of food filters include beverage filters such as coffee bags and tea bags. Examples of food packaging materials include food packaging bags, food packaging paper, and lids for food packaging containers.

[0081] Since the nonwoven fabric I and the laminated sheet are biodegradable, the nonwoven fabric I, the laminated sheet, and food products made therefrom will biodegrade if left in an environment where microorganisms are present after use, so no special disposal treatment is required and they are environmentally friendly.

[0082] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0083] The measurement and evaluation methods used in the examples and comparative examples are as follows: (1) Basis weight, thickness, and density of nonwoven fabric or laminated sheet The basis weight of a nonwoven fabric or laminated sheet is calculated based on the unit area (m 2The thickness of the nonwoven fabric or laminate sheet was measured with a thickness gauge. The density of the nonwoven fabric or laminate sheet was calculated based on the basis weight and thickness. (2) Tensile strength and breaking elongation of nonwoven fabric or laminate sheet The load value (g) at break was measured in the longitudinal direction (machine direction, MD, in which the nonwoven fabric flows during continuous production) and the transverse direction (direction perpendicular to the MD direction, CD) of the nonwoven fabric or laminate sheet in accordance with the nonwoven fabric interlining test method of JIS L 1085 using a sample piece 5 cm wide and 20 cm long at a grip interval of 10 cm and a pulling speed of 30 cm / min, and the measured load value was calculated as the mass per unit area (g / m 2) and calculated in 15 mm width units to determine the tensile strength. The elongation at break (the elongation relative to the gripping distance) was determined as the breaking elongation. (3) Mass-average molecular weight (Mw) 10 mg of sample was dissolved in 10 mL of chloroform, and insoluble matter was removed by filtration. The resulting solution (filtrate) was subjected to molecular weight measurement using a Shimadzu GPC system equipped with a Shodex K805L (300 x 8 mm, two connected tubes) (Showa Denko K.K.) and chloroform as the mobile phase. Commercially available standard polystyrene was used as the molecular weight standard sample. (4) Composition ratio of poly-(3-hydroxybutyrate-co-3-hydroxyhexanoate) Approximately 20 mg of the sample was added to 2 mL of a sulfuric acid-methanol mixture (15:85) and 2 mL of chloroform, sealed, and heated at 100°C for 140 minutes to obtain the methyl ester of the polyester decomposition product. After cooling, 1.5 g of sodium bicarbonate was added little by little to neutralize the mixture, and the mixture was left to stand until the evolution of carbon dioxide gas ceased. 4 mL of diisopropyl ether was added, mixed thoroughly, and then centrifuged. The composition of the hydroxyalkanoic acid methyl ester of the polyester decomposition product in the supernatant was analyzed by capillary gas chromatography to determine the composition ratio (monomer ratio) of the P3HB3HH monomer unit. The gas chromatograph used was a GC-17A manufactured by Shimadzu Corporation, and the capillary column used was a NEUTRA BOND-1 manufactured by GL Sciences (column length 25 m, column inner diameter 0.25 mm, liquid film thickness 0.4 μm). The temperature conditions were as follows: initial temperature 100 ° C. to 200 ° C. at a rate of 8 ° C. / min, and further temperature increase from 200 ° C. to 290 ° C. at a rate of 30 ° C. / min. (5) Melt flow rate (MFR) Measured in accordance with JIS K 7210-1 under conditions of a temperature of 160°C and a load of 5 kg (49 N). (6) Single fiber fineness, tensile strength, elongation at break, and initial modulus of fiber The single fiber fineness of staple fibers was measured in accordance with JIS L 1015. The tensile strength, elongation, and elongation modulus of elasticity (when stretched to 3% of the length when the initial load was applied) of staple fibers were measured in accordance with JIS L 1015, and were defined as the tensile strength, elongation at break, and initial modulus, respectively. The single fiber fineness and tensile strength (tensile strength) of drawn yarns were measured in accordance with JIS L 1013.(7) Melting Point: A differential scanning calorimeter (DSC) [Seiko Instruments Inc., DSC6200] was used. Specifically, 5 to 6 mg of sample was melted by heating from 40°C to 180°C at a heating rate of 10°C / min, then crystallized by cooling from 180°C to 40°C at a heating rate of 10°C / min, and then heated from 40°C to 180°C at a heating rate of 10°C / min. The melting point was determined as the melting peak temperature in the DSC curve obtained during the second heating. (8) Heat Sealability (Nonwoven Fabric / Laminated Sheet and Nonwoven Fabric, Nonwoven Fabric / Laminated Sheet and Kraft Paper) (a) Adhesion Strength of Heat Seal Portion (Heat Seal Strength) Test pieces for evaluating heat seal strength were prepared as follows. Two sheets of nonwoven fabric (or laminate sheet), or one sheet of nonwoven fabric (or laminate sheet) and one sheet of kraft paper, were overlapped in the MD direction during the production of nonwoven fabric I, with the heat roll contact surfaces facing each other, to prepare a sample before heat sealing. Next, the top and bottom surfaces of the overlapping set of samples were sandwiched between polyimide films, and the sample was sandwiched between the upper and lower heating plates of a heat sealing device. Thermocompression bonding (heat sealing) was performed for 1 second at a load of 0.30 MPa. After completion, the overlapping set of samples was promptly pulled out and left for 1 day before measuring the heat seal strength. When preparing the overlapping set of samples, the upper and lower heating plates of the heat sealing device were adjusted so that heat sealing was performed perpendicular to the MD direction of nonwoven fabric I. The hot platen temperatures during thermocompression bonding were set at 140°C to 190°C in 10°C increments and 240°C for heat sealing between nonwoven fabrics (or between nonwoven fabric I of laminated sheets), and at 150°C to 200°C in 10°C increments for heat sealing between nonwoven fabrics (or nonwoven fabric I of laminated sheets) and kraft paper. A set of overlapping samples after heat sealing was used as a test piece for measurement, and T-peel strength was measured using a Tensilon universal testing machine RTG-1210 (manufactured by A&D Co., Ltd.) under the following conditions in accordance with JIS K 6854-2 (Adhesives - Peel adhesion strength test method - Part 2: 180-degree peel). The maximum load test force at the time of peeling of the test piece was measured and used as the heat seal strength.Initial length of test piece for evaluating 180-degree T-peel: 20 mm Tensile speed: 20 mm / min Load cell: ORIENTEC load cell, model UR-50N-D (rated capacity: 50 N) (b) Peel morphology of adhesiveness This test piece was used to measure the heat seal strength between nonwoven fabrics (or between nonwoven fabrics I of laminated sheets), and the test piece after peeling (heat seal temperature 170°C or higher, specifically 180°C) was observed and the peel morphology of adhesiveness was qualitatively evaluated according to the following evaluation criteria. <Evaluation criteria> The peel morphology of adhesiveness of the test piece after measuring the heat seal strength was scored as shown below, and the average of five measurements was calculated and evaluated according to the following four-level criteria. 0 points: Substrate failure (no peeling or failure in the heat-sealed portion, but failure of the nonwoven fabric member) 2 points: Interfacial delamination (no failure in the nonwoven fabric layer in the heat-sealed portion, but peeling at the interface between the nonwoven fabrics) 5 points: Material failure (no peeling observed at the interface between the nonwoven fabrics in the heat-sealed portion, but failure at the inner layer of the nonwoven fabric) A: Peeling morphology score of 3 to 5, excellent as a heat-sealed product B: Peeling morphology score of 2.5 to less than 3, applicable to heat-sealed products C: Peeling morphology score of 2 to less than 2.5, applicable to heat-sealed products depending on the application D: Peeling morphology score of 0 to less than 2, not applicable to heat-sealed products (9) Strength of nonwoven fabric / laminated sheet after heat sealing The same test as in (8) (b) Adhesion peeling morphology was conducted and evaluated according to the following evaluation criteria. <Evaluation criteria> After measuring the heat seal strength, the peeling mode of the adhesive of the test piece was classified into substrate failure, interfacial peeling, or material failure, and the presence or absence of substrate failure was evaluated after five measurements. None: The strength of the nonwoven fabric / laminate sheet after heat sealing is sufficient and it can withstand use. Yes: The strength of the nonwoven fabric / laminate sheet at the heat seal part is insufficient and it cannot be used.

[0084] (Production Example 1) P3HB3HH was a copolymer (manufactured by Kaneka Corporation, biodegradable polymer Green Planet (registered trademark)) having a molar composition ratio of 3HB units / 3HH units of 94 / 6, Mw of 450,000, MFR of 0.5 g / 10 min, and melting point of 155 ° C. Pentaerythritol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., "Neuraizer P") was used as the nucleating agent, and erucic acid amide (lubricant 1) and behenic acid amide (lubricant 2) were used as the lubricants. 100 parts by mass of P3HB3HH, 1.0 part by mass of the nucleating agent, 0.5 parts by mass of lubricant 1, and 0.5 parts by mass of lubricant 2 were dry-blended, and the mixture was melt-kneaded at 160 ° C. using an extruder and pelletized to obtain a pellet-shaped resin composition. The resulting pellet-shaped resin composition had an Mw of 370,000, an MFR of 11 g / 10 min, and a melting point of 153 ° C. The resin composition (pellets) was melted in a single-screw extruder with a screw diameter of 40 mm, the flow rate was adjusted with a gear pump, and the resin composition (pellets) was extruded at a melt spinning temperature of 155 ° C. from a spinning nozzle (hole diameter 0.5 mm, outlet hole shape: circular) into a space (quenching farm) where air (quench air) was blown at 20 ° C. and 1.0 m / s, and an oil agent was added, and the filament was taken up at a spinning speed of 280 m / min with a roll heated to 40 ° C. to obtain an undrawn filament. Subsequently, the undrawn filament was stretched 2.0 times with a roll heated to 30 ° C., and then relaxed 10% with a heated roll (about 100 ° C.) to obtain a drawn yarn. The drawn yarn had a single fiber fineness of 4.5 dtex, a tensile strength of 1.21 cN / dtex, a melting point of 151° C., and an MFR of 53 g / 10 min. The drawn yarn obtained above was cut to a fiber length of 5 mm, to obtain P3HB3HH short fiber 1.

[0085] (Production Example 2) A pellet-shaped resin composition was obtained in the same manner as in Production Example 1, except that a copolymer (manufactured by Kaneka Corporation, biodegradable polymer Green Planet (registered trademark)) having a molar composition ratio of 3HB units / 3HH units of 94 / 6, a Mw of 240,000, an MFR of 55 g / 10 min, and a melting point of 152 ° C. was used as P3HB3HH. The obtained pellet-shaped resin composition had an Mw of 190,000, an MFR of 76 g / 10 min, and a melting point of 151 ° C. A drawn yarn was obtained in the same manner as in Production Example 1, except that the obtained resin composition (pellets) was used. The obtained drawn yarn had a single fiber fineness of 4.5 dtex, a tensile strength of 1.22 cN / dtex, a melting point of 149 ° C., and an MFR of 87 g / 10 min. The drawn yarn obtained above was cut to a fiber length of 5 mm to obtain P3HB3HH short fiber 2.

[0086] (Production Example 3) A pellet-shaped resin composition was obtained in the same manner as in Production Example 1, except that a copolymer (manufactured by Kaneka Corporation, biodegradable polymer Green Planet (registered trademark)) having a molar composition ratio of 3HB units / 3HH units of 94 / 6, Mw of 500,000, MFR of 0.2 g / 10 min, and melting point of 159 ° C. was used as P3HB3HH. The obtained pellet-shaped resin composition had an Mw of 450,000, an MFR of 0.2 g / 10 min, and a melting point of 157 ° C. The resulting resin composition (pellets) was melted in a single-screw extruder with a screw diameter of 25 mm, the flow rate was adjusted with a gear pump, and the melt spinning temperature was 165 ° C. The extrusion was performed from a spinning nozzle (hole diameter 0.5 mm, outlet hole shape: circular) into a space (quenching farm) where air (quench air) was blown at 20 ° C. and 1.0 m / s, and an oil solution was added. The filament was taken up at a spinning speed of 280 m / min with a roll heated to 40 ° C. to obtain an undrawn filament. Subsequently, a drawn yarn was obtained in the same manner as in Production Example 1. The obtained drawn yarn had a single fiber fineness of 4.5 dtex, a tensile strength of 1.84 cN / dtex, a melting point of 153 ° C., and an MFR of 28 g / 10 min. The drawn yarn obtained above was cut to a fiber length of 5 mm to obtain P3HB3HH-based short fiber 3.

[0087] (Production Example 4) P3HB3HH staple fiber 4 was obtained in the same manner as in Production Example 3, except that the melt spinning temperature was changed to 170°C.

[0088] (Production Example 5) P3HB3HH staple fiber 5 was obtained in the same manner as in Production Example 2, except that the melt spinning temperature was changed to 160°C.

[0089] The single fiber fineness, tensile strength, elongation at break, initial modulus of elasticity, melting point, Mw and MFR of the P3HB3HH staple fibers 1 to 5 of Production Examples 1 to 5 were measured as described above, and the results are shown in Table 1 below.

[0090]

[0091] Example 1 A nonwoven fabric was produced by a wet papermaking method. 50% by mass of pulp (average fiber length 6 mm, average fiber diameter 10 μm) as a cellulose-based fiber and 50% by mass of P3HB3HH staple fiber 1 as a P3HA-based fiber were mixed, and the mixed fibers were dispersed in water to a fiber concentration of 0.01 to 0.5% by mass. The resulting fiber slurry was made into paper using a combination inclined short wire, cylinder, and former papermaking machine. The resulting wet fiber web was dried by passing it through a heated roll of a Yankee dryer at a temperature of 110 to 120°C, thereby thermally bonding the fibers together, and a staple fiber nonwoven fabric (mixed fiber nonwoven fabric) having the basis weight shown in Table 2 was obtained.

[0092] Example 2 A staple fiber nonwoven fabric (mixed fiber nonwoven fabric) having the basis weight shown in Table 2 was obtained in the same manner as in Example 1, except that P3HB3HH staple fiber 2 was used instead of P3HA fiber.

[0093] (Example 3) A staple fiber nonwoven fabric (mixed fiber nonwoven fabric) having the basis weight shown in Table 2 was obtained in the same manner as in Example 1, except that the blending ratio was changed to 35% by mass / 65% by mass of pulp / P3HB3HH-based staple fiber 1.

[0094] (Example 4) A staple fiber nonwoven fabric (mixed fiber nonwoven fabric) having the basis weight shown in Table 2 was obtained in the same manner as in Example 1, except that the mixing ratio of pulp / P3HB3HH staple fiber 1 was changed to 45% by mass / 55% by mass.

[0095] (Example 5) A staple fiber nonwoven fabric (mixed fiber nonwoven fabric) having the basis weight shown in Table 2 was obtained in the same manner as in Example 1, except that the mixing ratio of pulp / P3HB3HH staple fiber 1 was changed to 60 mass% / 40 mass%.

[0096] Example 6 A staple fiber nonwoven fabric (laminate sheet) having the basis weight shown in Table 2 was obtained in the same manner as in Example 1, except that the blending ratio of pulp / P3HB3HH staple fiber 1 was changed to 60% by mass / 40% by mass, and a staple fiber web containing 100% by mass of pulp was also combined. When passing through the heated rolls, the fiber sheet composed of pulp and P3HB3HH staple fiber 1 was made to come into contact with the heated rolls.

[0097] Example 7 A staple fiber nonwoven fabric (mixed fiber nonwoven fabric) having the basis weight shown in Table 2 was obtained in the same manner as in Example 1, except that P3HB3HH staple fiber 4 was used instead of the P3HA fiber.

[0098] Comparative Example 1 A staple fiber nonwoven fabric having the basis weight shown in Table 3 was obtained in the same manner as in Example 1, except that P3HB3HH staple fiber 3 was used instead of the P3HA fiber.

[0099] Comparative Example 2 A staple fiber nonwoven fabric having the basis weight shown in Table 3 was obtained in the same manner as in Example 1, except that the blending ratio of pulp / P3HB3HH staple fiber 1 was changed to 70% by mass / 30% by mass.

[0100] Comparative Example 3 A staple fiber nonwoven fabric having the basis weight shown in Table 3 was obtained in the same manner as in Example 1, except that the mixing ratio of pulp / P3HB3HH staple fiber 1 was changed to 20% by mass / 80% by mass.

[0101] Comparative Example 4 A staple fiber nonwoven fabric having the basis weight shown in Table 3 was obtained in the same manner as in Example 1, except that P3HB3HH staple fiber 5 was used instead of the P3HA fiber.

[0102] In the examples and comparative examples, the basis weight, thickness, density, tensile strength, elongation at break, heat sealability, and strength after heat sealing of the short-fiber nonwoven fabrics (wetlaid nonwoven fabrics) or laminated sheets were measured and evaluated as described above, and the results are shown in Tables 2 and 3 below.

[0103]

[0104]

[0105] As can be seen from the data in Table 2, the mixed fiber nonwoven fabrics of Examples 1 to 5 and 7 and the laminate sheet of Example 6 had high heat seal strength at a temperature of 170°C or higher, and the adhesion state of peeling after heat sealing was evaluated as C or higher, indicating good heat sealability.

[0106] On the other hand, as can be seen from the data in Table 3, the mixed fiber nonwoven fabric of Comparative Example 1, which uses P3HB3HH staple fibers having an MFR of less than 35 g / 10 min, has high heat seal strength at temperatures of 170°C or higher, but the evaluation of the adhesive form in peeling after heat sealing was D, making it unsuitable for heat-sealed products and poor in heat sealability. Also, Comparative Example 2, in which the content of cellulose fiber (A) is 70% by mass or more relative to the total mass of cellulose fiber (A) and poly(3-hydroxyalkanoate) fiber (B), not only has low heat seal strength at temperatures of 170°C or higher, but also the evaluation of the adhesive form in peeling after heat sealing was D, making it unsuitable for heat-sealed products and poor in heat sealability. Furthermore, Comparative Example 3, in which the content of cellulose fiber (A) was less than 30% by mass relative to the total mass of cellulose fiber (A) and poly(3-hydroxyalkanoate) fiber (B), had low heat seal strength at temperatures of 170°C or higher, and the bond state after peeling after heat sealing was evaluated as D, making it unsuitable for heat-sealed products and poor in heat sealability. Furthermore, the mixed fiber nonwoven fabric of Comparative Example 4, which used P3HB3HH staple fiber with an MFR of more than 90 g / 10 min, had high heat seal strength at temperatures of 170°C or higher, but the bond state after peeling after heat sealing was evaluated as D, making it unsuitable for heat-sealed products and poor in heat sealability.

[0107] The present invention is not particularly limited, and may include, for example, one or more of the following embodiments.

[0108] [1] A nonwoven fabric comprising a cellulose-based fiber and a poly(3-hydroxyalkanoate)-based fiber containing a poly(3-hydroxyalkanoate)-based resin, wherein the poly(3-hydroxyalkanoate)-based fiber has a melt flow rate of 35 g / 10 min or more and 90 g / 10 min or less, measured in accordance with JIS K 7210-1 at a temperature of 160°C and a load of 5 kg (49 N), and the content of the cellulose-based fiber is 30% by mass or more and less than 70% by mass, based on the total mass of the cellulose-based fiber and the poly(3-hydroxyalkanoate)-based fiber. [2] The nonwoven fabric according to [1], wherein the content of the cellulose-based fiber is 40% by mass or more and 65% by mass or less, based on the total mass of the cellulose-based fiber and the poly(3-hydroxyalkanoate)-based fiber. [3] The nonwoven fabric according to [1] or [2], wherein the poly(3-hydroxyalkanoate)-based fiber has a mass average molecular weight of 100,000 or more but less than 300,000. [4] The nonwoven fabric according to any one of [1] to [3], wherein the poly(3-hydroxyalkanoate)-based resin is a copolymer containing 3-hydroxybutyrate units and other hydroxyalkanoate units. [5] The nonwoven fabric according to any one of [1] to [4], wherein the content of the 3-hydroxybutyrate units is more than 24 mol% and not more than 99 mol%, relative to the total 100 mol% of the 3-hydroxybutyrate units and the other hydroxyalkanoate units. [6] The nonwoven fabric according to any one of [1] to [5], wherein the nonwoven fabric is a staple fiber nonwoven fabric. [7] The nonwoven fabric according to any one of [1] to [6], wherein the nonwoven fabric is a wetlaid nonwoven fabric. [8] The nonwoven fabric according to any one of [1] to [7], wherein the nonwoven fabric is a mixed fiber nonwoven fabric. [9] A laminated sheet comprising a layer containing the nonwoven fabric according to any one of [1] to [8] and a layer containing nonwoven fabric II, wherein the nonwoven fabric II contains cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, and the content of the cellulose-based fibers in the nonwoven fabric II is 70% by mass or more and 100% by mass or less relative to the total mass of the cellulose-based fibers and the poly(3-hydroxyalkanoate)-based fibers.

[10] The laminated sheet according to [9], wherein the nonwoven fabric II is a wet-laid nonwoven fabric.

[11] A food product comprising the nonwoven fabric according to any one of [1] to [8], or the laminated sheet according to [9] or

[10] .

[12] The food product according to

[11] , wherein the food product is a food filter or a food packaging material.

Claims

1. A nonwoven fabric comprising cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, wherein the poly(3-hydroxyalkanoate)-based fibers have a melt flow rate of 35 g / 10 min or more and 90 g / 10 min or less, measured in accordance with JIS K 7210-1 at a temperature of 160°C and a load of 5 kg (49 N), and the content of the cellulose-based fibers is 30% by mass or more and less than 70% by mass of the total mass of the cellulose-based fibers and the poly(3-hydroxyalkanoate)-based fibers.

2. The nonwoven fabric according to claim 1, wherein the content of the cellulosic fibers is 40% by mass or more and 65% by mass or less, based on the total mass of the cellulosic fibers and the poly(3-hydroxyalkanoate) fibers.

3. The nonwoven fabric according to claim 1, wherein the poly(3-hydroxyalkanoate) fiber has a mass average molecular weight of 100,000 or more and less than 300,000.

4. The nonwoven fabric according to claim 1, wherein the poly(3-hydroxyalkanoate) resin is a copolymer containing 3-hydroxybutyrate units and other hydroxyalkanoate units.

5. The nonwoven fabric according to claim 1, wherein the content of the 3-hydroxybutyrate units is more than 24 mol% and not more than 99 mol%, based on 100 mol% of the total of the 3-hydroxybutyrate units and the other hydroxyalkanoate units.

6. The nonwoven fabric according to claim 1, which is a staple fiber nonwoven fabric.

7. The nonwoven fabric according to claim 1, which is a wet-laid nonwoven fabric.

8. The nonwoven fabric according to claim 1, which is a mixed fiber nonwoven fabric.

9. A laminated sheet comprising a layer containing the nonwoven fabric according to any one of claims 1 to 8 and a layer containing nonwoven fabric II, wherein the nonwoven fabric II contains cellulosic fibers and poly(3-hydroxyalkanoate) fibers containing a poly(3-hydroxyalkanoate) resin, and the content of the cellulosic fibers in the nonwoven fabric II is 70% by mass or more and 100% by mass or less relative to the total mass of the cellulosic fibers and the poly(3-hydroxyalkanoate) fibers.

10. The laminated sheet according to claim 9, wherein nonwoven fabric II is a wet-laid nonwoven fabric.

11. A food product comprising the nonwoven fabric according to any one of claims 1 to 8.

12. The food product according to claim 11, wherein the food product is a food filter or a food packaging material.

13. A food product comprising the laminated sheet of claim 9.

14. The food product according to claim 13, wherein the food product is a food filter or a food packaging material.

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