Nonwoven fabric and multilayer sheet including same, product for foods which includes said nonwoven fabric or multilayer sheet, and method for producing said product for foods

Abstract

The present invention relates to a nonwoven fabric comprising cellulose fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, wherein the water contact angle on one of the surfaces of the nonwoven fabric is 25° to 90° inclusive. In the case where the nonwoven fabric is a wet nonwoven fabric, a wet nonwoven fabric in which the water contact angle on one surface is 25° to 90° inclusive can be obtained by drying a wet sheet which contains, at a specified ratio, the poly(3-hydroxyalkanoate)-based fibers containing the poly(3-hydroxyalkanoate)-based resin at a specified temperature. Thus, a nonwoven fabric having good heat-sealing properties, a multilayer sheet including the nonwoven fabric, a product for foods which includes the nonwoven fabric or the multilayer sheet, and a method for producing the product for foods are provided.

Description

Nonwoven fabric, laminated sheet containing the same, food product containing them, and method for producing the same

[0001] The present invention relates to a biodegradable nonwoven fabric, a laminated sheet containing the same, a food product containing the same, and a method for producing the same.

[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, a food product containing them, and a method for producing the same.

[0006] One or more embodiments of the present invention relate to a nonwoven fabric comprising cellulosic fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, wherein one surface of the nonwoven fabric has a water contact angle of 25° or more and 90° or less.

[0007] One or more embodiments of the present invention relate to a laminate sheet including a layer comprising nonwoven fabric I and a layer comprising nonwoven fabric II, wherein nonwoven fabric I is the nonwoven fabric described above, nonwoven fabric II comprises cellulosic fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, and the cellulosic fiber content in nonwoven fabric II is greater than the cellulosic fiber content in nonwoven fabric I.

[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] One or more embodiments of the present invention relate to a method for producing a nonwoven fabric, the method including: Step I obtaining a wet sheet containing cellulosic fibers and poly(3-hydroxyalkanoate) fibers that contain a poly(3-hydroxyalkanoate) resin; and Step II drying the wet sheet in a dryer, wherein the wet sheet contains more than 20% by mass and less than 80% by mass of poly(3-hydroxyalkanoate) fibers and more than 20% by mass and less than 80% by mass of cellulosic fibers relative to the total mass of the cellulosic fibers and the poly(3-hydroxyalkanoate) fibers, and wherein the drying temperature in Step II is [Tmf - 41°C] or higher and [Tmf - 25°C] or lower, where Tmf is the melting point of the poly(3-hydroxyalkanoate) fibers.

[0011] The present invention can provide a nonwoven fabric having good heat-sealing properties, a laminated sheet containing the nonwoven fabric, a food product containing the nonwoven fabric or the laminated sheet, and a method for producing the food product.

[0012] The present inventors conducted extensive research to solve the above-mentioned problems. As a result, they discovered that in a nonwoven fabric (hereinafter referred to as nonwoven fabric I) comprising cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers (hereinafter also referred to as P3HA-based fibers) containing a poly(3-hydroxyalkanoate)-based resin (hereinafter also referred to as P3HA), by setting the water contact angle of one surface (hereinafter also referred to as the first surface) to be 25° or more and 90° or less, heat sealing properties are significantly improved when the first surface is used as the heat sealing surface. In one or more embodiments of the present invention, when the water contact angles of the two surfaces of nonwoven fabric I are different, the surface with the larger water contact angle is the first surface, and the surface with the smaller water contact angle is the second surface. Note that when the water contact angles of both surfaces of nonwoven fabric I are the same, either surface may be used as the first surface. However, in the case of a nonwoven fabric in which interfiber bonding is performed using a heated roll, the surface that contacted the heated roll is used as the first surface, and the other surface is used as the second surface. Thus, in one or more embodiments of the present invention, the water contact angle of at least one surface may be 25° or more and 90° or less, and the water contact angles of both surfaces may be 25° or more and 90° or less.

[0013] In one or more embodiments of the present invention, the water contact angle of the surface of nonwoven fabric I is a parameter that indicates the surface texture (degree of unevenness) of the nonwoven fabric surface and the presence of poly(3-hydroxyalkanoate)-based fibers. When the water contact angle of the surface of nonwoven fabric I is 25° or more and 90° or less, the heat sealability is significantly improved when this surface is used as a heat seal surface. Therefore, the water contact angle of the surface of nonwoven fabric I can be used as an indicator of the heat sealability of nonwoven fabric I. When the water contact angle of the surface of nonwoven fabric I is less than 25°, the presence of poly(3-hydroxyalkanoate)-based fibers on this surface is low or excessive, which is presumed to result in reduced heat sealability when this surface is used as a heat seal surface. When the water contact angle of the surface of nonwoven fabric I is more than 90°, the presence of poly(3-hydroxyalkanoate)-based fibers on this surface is too high, which is presumed to result in reduced heat sealability when this surface is used as a heat seal surface. The degree of unevenness of the nonwoven fabric surface is affected by the amount of poly(3-hydroxyalkanoate)-based fibers present; if the amount of poly(3-hydroxyalkanoate)-based fibers present is too small or too large, the unevenness of the nonwoven fabric surface will increase, resulting in a smaller water contact angle. For a given degree of unevenness of the nonwoven fabric surface, a larger amount of poly(3-hydroxyalkanoate)-based fibers present on the nonwoven fabric surface will increase the water contact angle. In one or more embodiments of the present invention, as described below, by adjusting the content of poly(3-hydroxyalkanoate)-based fibers in the web (fiber web) and the temperature during fiber bonding of the web with Samar Bond within predetermined ranges, a nonwoven fabric I having a water contact angle of 25° or more and 90° or less on the first surface can be obtained.

[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] The melt flow rate (hereinafter also referred to as MFR160) of the P3HA fiber measured in accordance with JIS K 7210-1 at a temperature of 160°C and a load of 5 kg (49 N) is not particularly limited, but is preferably 0 g / 10 min to 140 g / 10 min, more preferably 30 g / 10 min to 140 g / 10 min, even more preferably 37 g / 10 min to 100 g / 10 min, and even more preferably 50 g / 10 min to 87 g / 10 min. When the MFR160 of the P3HA fiber is in the above-mentioned range, the fluidity of the P3HA fiber becomes appropriate, and the adhesive strength (hereinafter also referred to as heel sheet strength) of the heat-sealed portion between nonwoven fabrics I containing the P3HA fiber and cellulose fiber, or between nonwoven fabric I and other materials, such as graft paper, is likely to be improved.

[0016] The melt flow rate (hereinafter also referred to as MFR175) of the P3HA fiber measured in accordance with JIS K 7210-1 at a temperature of 175°C and a load of 5 kg (49 N) is not particularly limited, but is preferably 20 g / 10 min to 250 g / 10 min, more preferably 40 g / 10 min to 200 g / 10 min, and even more preferably 60 g / 10 min to 150 g / 10 min. When the MFR175 of the P3HA fiber is in the above-mentioned range, the fluidity of the P3HA fiber becomes appropriate, and the heat seal strength between nonwoven fabrics I containing the P3HA fiber and cellulose fiber, or between the nonwoven fabric I and other materials, such as graft paper, is likely to be improved.

[0017] The mass average molecular weight (Mw) of the P3HA fiber is not particularly limited, but is preferably 100,000 or more but less than 300,000, more preferably 150,000 or more but 280,000 or less, and even more preferably 170,000 or more but 240,000 or less, from the viewpoint of fiber productivity and heat sealability of the nonwoven fabric. 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.

[0018] The melting point of the P3HA fiber 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. In this specification, the melting point can be measured as described in the examples.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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):

[0025]

[0026] 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 Examples of the alkyl group include linear or branched alkyl groups such as methyl, ethyl, propyl, methylpropyl, butyl, isobutyl, t-butyl, pentyl, and hexyl groups.

[0027] 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%.

[0028] 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).

[0029] 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.

[0030] 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 the 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.

[0031] 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.

[0032] The MFR160 of P3HA is not particularly limited as long as the MFR160 or MFR175 of the P3HA fiber satisfies the above-mentioned range, but for example, it is preferably 0 g / 10 min or more and 100 g / 10 min or less, more preferably 0.1 g / 10 min or more and 100 g / 10 min or less, even 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 MFR160 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.

[0033] The MFR175 of P3HA is not particularly limited as long as the MFR160 or MFR175 of the P3HA fiber satisfies the above-mentioned range, but is, for example, preferably 10 g / 10 min or more and 150 g / 10 min or less, more preferably 25 g / 10 min or more and 125 g / 10 min or less, and even more preferably 40 g / 10 min or more and 100 g / 10 min or less. When the MFR175 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Among the lubricants described above, compounds that have 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.

[0040] 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.

[0041] 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 singly or in combination of two or more.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 can also be determined appropriately depending on the contents of the other resin components and additive components in the P3HA-based fiber.

[0046] The MFR160 of the resin composition is not particularly limited as long as the MFR160 or MFR175 of the P3HA fiber satisfies the above-mentioned range, but is, for example, preferably 0 g / 10 min or more and 100 g / 10 min or less, more preferably 0.1 g / 10 min or more and 100 g / 10 min or less, even 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 MFR160 of the resin composition is within the above-mentioned range, the fluidity of the molten resin becomes an appropriate range, and fiberization becomes good.

[0047] The MFR175 of the resin composition is not particularly limited as long as the MFR160 or MFR175 of the P3HA fiber satisfies the above-mentioned range, but is preferably 10 g / 10 min or more and 150 g / 10 min or less, more preferably 25 g / 10 min or more and 125 g / 10 min or less, and even more preferably 40 g / 10 min or more and 100 g / 10 min or less. When the MFR175 of the resin composition is within the above-mentioned range, the fluidity of the molten resin becomes an appropriate range, and fiberization becomes good.

[0048] 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.

[0049] 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.

[0050] 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 (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 160 or MFR 175 of the P3HA-based fiber is 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The drawn filaments may be used as they are as long P3HA fibers, but may also be cut to a predetermined fiber length and used as short P3HA fibers.

[0055] (Cellulosic Fibers) The cellulose fibers are not particularly limited, and may be natural cellulose fibers or regenerated cellulose fibers.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] (Nonwoven fabric I and its manufacturing method) Nonwoven fabric I has a water contact angle of 25° or more and 90° or less. This provides high heat sealability when this surface is used as a heat seal surface, particularly at temperatures of 150° or more and 190° or less. From the viewpoint of further improving heat sealability when the first surface is used as a heat seal surface, the lower limit of the water contact angle of the first surface of nonwoven fabric I is preferably 30° or more, and more preferably 33° or more. From the viewpoint of further improving heat sealability when the first surface is used as a heat seal surface, the upper limit of the water contact angle of the first surface of nonwoven fabric I is preferably 85° or less, and more preferably 80° or less. In this specification, the water contact angle can be measured as described in the examples.

[0060] In nonwoven fabric I, it is sufficient that the water contact angle of the first surface satisfies the above-mentioned range, and the blending amounts of the P3HA fiber and the cellulose fiber are not particularly limited. However, from the viewpoint of easily making the water contact angle of the first surface satisfy the above-mentioned range, it is preferable that the content of the P3HA fiber is more than 20% by mass and less than 80% by mass, and the content of the cellulose fiber is more than 20% by mass and less than 80% by mass, relative to the total mass of the P3HA fiber and the cellulose fiber. It is also preferable that the content of the cellulose fiber is 25% by mass or more and 75% by mass or less, and the content of the P3HA fiber is 25% by mass or more and 75% by mass or less. The content of the cellulose-based fiber is preferably 5% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less of the P3HA-based fiber, even more preferably 30% by mass or more and 65% by mass or less and 35% by mass or more and 70% by mass or less of the P3HA-based fiber, and even more preferably 31% by mass or more and 60% by mass or less and 40% by mass or more and 69% by mass or less of the P3HA-based fiber. The P3HA-based fiber and the cellulose-based fiber are appropriately used as described above. When the nonwoven fabric I is a wetlaid nonwoven fabric, in order for the water contact angle of the first surface to satisfy the above-described range, the content of the P3HA-based fiber needs to be less than 80% by mass and the content of the cellulose-based fiber needs to be more than 20% by mass relative to the total mass of the P3HA-based fiber and the cellulose-based fiber. In other words, when nonwoven fabric I is a wet-laid nonwoven fabric, a configuration in which the water contact angle of the first surface is 25° or more and 90° or less includes a configuration in which the P3HA-based fiber content is less than 80% by mass and the cellulose-based fiber content is more than 20% by mass relative to the total mass of the P3HA-based fiber and the cellulose-based fiber.

[0061] 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.

[0062] 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.

[0063] 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 2 Below, 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The heat seal strength between nonwoven fabrics 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 heat seal strength between nonwoven fabrics I at temperatures in the range of 150°C to 190°C, or any temperature within this range, is preferably 1000mN / 15mm or more, or even 1500mN / 15mm or more, or 2000mN / 15mm or more. Furthermore, when used in food products such as food filters and food packaging materials, the peeling mode of the heat-sealed adhesion between nonwoven fabrics I at temperatures in the range of 150°C to 190°C, or any temperature within this range, preferably does not result in substrate failure. In this specification, the heat seal strength between nonwoven fabrics can be measured as described in the examples.

[0069] Nonwoven fabric I, whose first surface has a water contact angle of 25° or more and 90° or less, can be obtained by adjusting the content of poly(3-hydroxyalkanoate)-based fibers in the web (fiber web) and the temperature when bonding the fibers of the web with Samar Bond within predetermined ranges. Specifically, the method for producing nonwoven fabric I includes a web-forming step and a fiber-to-fiber bonding step using a Samar bond. In the web-forming step, a web is produced in which the P3HA fiber content is more than 20% by mass but less than 80% by mass, and the cellulosic fiber content is more than 20% by mass but less than 80% by mass, relative to the total mass of the P3HA fiber and the cellulosic fiber. In the fiber-to-fiber bonding step using a Samar bond, the web is dry-heat treated at a temperature in the range of [Tmf - 41°C] or more and [Tmf - 25°C] or less, preferably at a temperature in the range of [Tmf - 40°C] or more and [Tmf - 25°C] or less, where Tmf is the melting point of the P3HA fiber, to thermally bond the fibers with the P3HA fiber, thereby obtaining nonwoven fabric I having a water contact angle of 25° or more and 90° or less on the first surface. If the P3HA fiber content in the web is too low, even if the dry heat treatment is performed within the above-mentioned range, the unevenness of the first surface will be large and the water contact angle of the first surface will be less than 25°. If the P3HA fiber content in the web is too high, even if the dry heat treatment is performed within the above-mentioned range, the water repellency derived from the P3HA fiber will be strong and the water contact angle of the first surface will exceed 90°. If the P3HA fiber content in the web is high and the dry heat treatment temperature is too high, the unevenness of the first surface will be large and the water contact angle of the first surface will be less than 25°. Even if the P3HA fiber content in the web is within the above-mentioned range, if the dry heat treatment temperature is low, the unevenness of the first surface will be large and the water contact angle of the first surface will be less than 25°. Even if the P3HA fiber content in the web is within the above-mentioned range, if the dry heat treatment temperature is high, the unevenness of the first surface will be large and the water contact angle of the first surface will be less than 25°.

[0070] The nonwoven fabric I can be preferably produced by a wet papermaking method, which includes a step I (web-forming step) of obtaining a wet sheet containing cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, and a step II (fiber-to-fiber bonding step) of drying the wet sheet in a dryer, and in the step I, the content of the P3HA-based fibers is more than 20% by mass relative to the total mass of the P3HA-based fibers and the cellulose-based fibers. A wet sheet (wet fiber web) is prepared having a P3HA fiber content of less than 80% by mass and a cellulosic fiber content of more than 20% by mass but less than 80% by mass, and in step 2, where Tmf is the melting point of the P3HA fiber, the wet sheet is dried (heat-treated) at a temperature in the range of [Tmf - 41°C] or more and [Tmf - 25°C] or less, preferably at a temperature in the range of [Tmf - 40°C] or more and [Tmf - 25°C] or less, thereby obtaining nonwoven fabric I having a water contact angle of 25° or more and 90° or less on the first surface.

[0071] Specifically, step 1 can be performed as follows. First, the above-described P3HA fiber and cellulose fiber (e.g., pulp) are mixed, the mixed fiber is dispersed in water, and the resulting fiber slurry is papermade 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 wet sheet falls within the above-mentioned range. For papermaking, for example, a cylinder wire papermaking machine, a long wire papermaking machine, a short wire papermaking machine, an inclined short wire papermaking machine, or a combination inclined short wire / cylinder wire / former papermaking machine can be appropriately used. When dispersing the mixed fiber in water, a dispersant or a dispersion aid may be used as necessary.

[0072] In step 2, a dryer commonly used in wet papermaking methods can be used as appropriate. From the viewpoint of productivity, etc., it is desirable to use a Yankee dryer. In the case of a Yankee dryer, the temperature of the heat roll is adjusted to between [Tmf - 41°C] and [Tmf - 25°C], preferably between [Tmf - 40°C] and [Tmf - 25°C], and the fibers are thermally bonded with the P3HA fiber. When a Yankee dryer is used in the drying step, the water contact angle of the surface in contact with the heat roll of the Yankee dryer is between 25° and 90°.

[0073] (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. Nonwoven fabric II also includes cellulosic fibers and P3HA fibers, similar to nonwoven fabric I, except that the content of the cellulosic fibers in nonwoven fabric II is greater than the content of the cellulosic fibers in nonwoven fabric I. As the cellulosic fibers and P3HA fibers, those described above can be used as appropriate.

[0074] In the nonwoven fabric II, the content of the cellulosic fibers is preferably 40% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 100% by mass or less, even more preferably 60% by mass or more and 100% by mass or less, still more preferably 70% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less, based on the total mass of the cellulosic fibers and the P3HA fibers. This tends to improve the strength of the laminate sheet.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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 at temperatures in the range of 150°C to 190°C, or any temperature within this range, is preferably 500 mN / 15 mm or more, 1000 mN / 15 mm or more, 1500 mN / 15 mm or more, or 2000 mN / 15 mm or more. Furthermore, when used in food products such as food filters and food packaging materials, the peeling mode of the heat seal adhesion between the nonwoven fabrics I in the laminated sheets at temperatures in the range of 150°C to 190°C, or any temperature within this range, preferably does not result in substrate failure. In this specification, the heat seal strength between the nonwoven fabrics I in the laminated sheets can be measured as described in the Examples.

[0082] Nonwoven fabric II may be a staple fiber nonwoven fabric or a wet-laid nonwoven fabric. The laminate sheet may be produced by laminating nonwoven fabric I and nonwoven fabric II, or by laminating the web constituting nonwoven fabric I with the web constituting nonwoven fabric II, and then bonding the fibers of the web constituting nonwoven fabric I and the web constituting nonwoven fabric II. When nonwoven fabric II is a wet-laid nonwoven fabric, the laminate sheet can be produced by a wet papermaking method. The wet papermaking can be carried out 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 together as two layers. When a Yankee dryer is used as the dryer, the temperature of the heat roll is adjusted to between [Tmf - 41°C] and [Tmf - 25°C], preferably between [Tmf - 40°C] and [Tmf - 25°C], and the laminate web is dried so that the wet sheet constituting nonwoven fabric I comes into contact with the heat roll.

[0083] (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.

[0084] 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, eliminating the need for special disposal treatment and making them environmentally friendly.

[0085] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0086] The measurement and evaluation methods used in the examples and comparative examples are as follows. (1) Water Contact Angle of Nonwoven Fabric: In an environment conditioned to room temperature of 23°C and humidity of 50%, a nonwoven fabric was cut to A4 size, spread on a horizontal, flat table, and pressed down on the four corners with weights to prevent sagging or wrinkles. A drop (0.05 mL) of pure water was vertically dropped onto the center of the nonwoven fabric using a micropipette from a height of approximately 30 cm, and the droplet pooling on the nonwoven fabric was observed from the horizontal direction. During observation, an image was taken with a camera, and the angle between the droplet and the nonwoven fabric was calculated from the vertical to horizontal dimensional ratio to obtain the contact angle. The image was taken after the droplet had been held for 10 seconds after dropping to confirm penetration of the droplet into the nonwoven fabric and eliminate the influence of evaporation of the droplet itself. (2) Basis weight, thickness, and density of nonwoven fabric or laminate sheet The basis weight of a nonwoven fabric or laminate sheet is calculated by dividing 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. (3) 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 defined as the breaking elongation. (4) 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. (5) 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. (6) Melt flow rate (MFR) Measured in accordance with JIS K 7210-1 at a temperature of 160°C or 175°C and a load of 5 kg (49 N). (7) 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.(8) 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 run. (9) Heat Sealability: (a) Adhesion Strength of Heat Sealed Portions (Heat Seal Strength). A test piece for evaluating heat seal strength was prepared as follows. Two nonwoven fabrics (or laminated sheets) were overlapped, aligned in the MD direction during the production of nonwoven fabric I, with the surfaces in contact with the heated rolls 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 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 the heat seal was performed perpendicular to the MD direction of the nonwoven fabric I. The heating plate temperature during thermocompression bonding was set between 150°C and 190°C in 10°C increments for heat sealing between nonwoven fabrics (or between nonwoven fabrics I of laminated sheets). A set of overlapping samples after heat sealing was used as a test piece for measurement, and T-peel strength was measured in accordance with JIS K 6854-2 (Adhesives -- Test method for peel adhesion strength -- Part 2: 180-degree peel) using a Tensilon universal material testing machine RTG-1210 (manufactured by A&D Co., Ltd.) under the following conditions to measure the maximum load test force when the test piece was peeled. The number of tests was n=5, and the average value of the measured values ​​of the five maximum load test forces was taken as the heat seal strength.Initial length of test piece for evaluating 180-degree T-shaped peel: 20 mm Tensile speed: 20 mm / min Load cell: Load cell manufactured by ORIENTEC Corporation, model number UR-50N-D (rated capacity: 50 N) (b) Evaluation of heat sealability Based on the heat seal strength, the heat sealability was qualitatively evaluated according to the following evaluation criteria, and the heat seal strength value was scored as shown below. The total score at each heat seal temperature (temperatures in 10°C increments from 150°C to 190°C) was calculated and evaluated on the following four-point scale. 0 points: 0mN / 15mm 1 point: 1 to 500mN / 15mm 3 points: 501 to 1000mN / 15mm 5 points: 1001 to 1500mN / 15mm 7 points: 1501 to 2000mN / 15mm 9 points: 2001 to 2500mN / 15mm 11 points: 2501 to 3000mN / 15mm 13 points: 3001 or more mN / 15mm <Evaluation criteria> A: 46 points or more, excellent as a heat-sealed product B: 26 to 45 points, suitable for heat-sealed products C: 1 point to 25 points, suitable for heat-sealed products depending on the application D: 0 points, not suitable for heat-sealing.

[0087] (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, MFR160 of 0.5 g / 10 min, and a 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 MFR160 of 11 g / 10 min, an MFR175 of 42 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 from a spinning nozzle (hole diameter 0.5 mm, outlet hole shape: circular) at a melt spinning temperature of 155 ° C. 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., an MFR160 of 53 g / 10 min, and an MFR175 of 95 g / 10 min. The drawn yarn obtained above was cut to a fiber length of 5 mm, to obtain P3HB3HH staple fiber 1.

[0088] The single fiber fineness, tensile strength, elongation at break, initial modulus, melting point, Mw, MFR160 and MFR175 of P3HB3HH staple fiber 1 of Production Example 1 were measured as described above, and the results are shown in Table 1 below.

[0089]

[0090] 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 short 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 wire, and former papermaking machine. The resulting wet sheet (wet fiber web) was dried by passing it through a hot roll of a Yankee dryer at a temperature of 110°C, whereby the fibers were thermally bonded to each other, resulting in a basis weight of approximately 40 g / m. 2 A short fiber nonwoven fabric (mixed fiber nonwoven fabric) was obtained.

[0091] Examples 2 to 4 Staple fiber nonwoven fabrics (mixed fiber nonwoven fabrics) were obtained in the same manner as in Example 1, except that the temperature of the heat roll of the Yankee dryer was changed as shown in Table 2 below.

[0092] Example 5 A short fiber nonwoven fabric (mixed fiber nonwoven fabric) was obtained in the same manner as in Example 4, except that the mixing ratio of pulp and P3HB3HH short fiber I was changed as shown in Table 2 below.

[0093] Example 6 A fiber web I in which the mixing ratio of pulp and P3HB3HH-based staple fiber I was pulp / P3HB3HH-based staple fiber 1 = 33 mass% / 67 mass% and a fiber web II in which the mixing ratio of pulp / P3HB3HH-based staple fiber 1 = 100 mass% / 0 mass% were combined, and a staple fiber nonwoven fabric (laminate sheet) having the basis weight shown in Table 2 below was obtained in the same manner as in Example 2, except that the fiber web I side was brought into contact with the heat roll of the Yankee dryer.

[0094] (Example 7) A staple fiber nonwoven fabric (laminate sheet) having the basis weight shown in Table 2 below was obtained in the same manner as in Example 6, except that the mixing ratio of pulp and P3HB3HH-based staple fiber I in fiber web I was set to pulp / P3HB3HH-based staple fiber 1 = 60 mass% / 40 mass%.

[0095] Comparative Examples 1 and 2 Staple fiber nonwoven fabrics (mixed fiber nonwoven fabrics) were obtained in the same manner as in Example 1, except that the temperature of the heat roll of the Yankee dryer was changed as shown in Table 3 below.

[0096] (Comparative Example 3) A short fiber nonwoven fabric (mixed fiber nonwoven fabric) was obtained in the same manner as in Example 1, except that the mixing ratio of pulp and P3HB3HH-based short fiber I was shown in Table 2 below and the temperature of the heat roll of the Yankee dryer was changed as shown in Table 3 below.

[0097] Comparative Example 4 A short fiber nonwoven fabric (mixed fiber nonwoven fabric) was obtained in the same manner as in Example 4, except that the mixing ratio of pulp and P3HB3HH short fiber I was changed as shown in Table 3 below.

[0098] In the examples and comparative examples, the water contact angle, basis weight, thickness, density, tensile strength, elongation at break, and heat sealability of the short-fiber nonwoven fabrics (wetlaid nonwoven fabrics) were measured and evaluated as described above, and the results are shown in the following Tables 2 and 3. In the following Table 2, the second surface in Examples 6 and 7 is the surface of nonwoven fabric II that is not in contact with nonwoven fabric I.

[0099]

[0100]

[0101] As can be seen from the data in Table 2, the wetlaid nonwoven fabrics of Examples 1 to 5 and the laminated sheets of Examples 6 and 7 had good heat sealability.

[0102] On the other hand, as can be seen from the data in Table 3, in Comparative Examples 1 and 2, the fiber web contains more than 20% by mass but less than 80% by mass of P3HA fiber, and more than 20% by mass but less than 80% by mass of cellulose fiber, relative to the total mass of the cellulose fiber and P3HA fiber, but the drying temperature (heat treatment temperature) is less than [Tmf - 41 ° C] or more than [Tmf - 25 ° C], so the resulting wetlaid nonwoven fabric has a water contact angle of less than 25 ° on the first surface and poor heat sealability. In Comparative Example 3, the drying temperature is in the range of [Tmf - 41 ° C] or more and [Tmf - 25 ° C] or less, but the fiber web contains 20% by mass or less of P3HA fiber and 80% by mass or more of cellulose fiber, relative to the total mass of the cellulose fiber and P3HA fiber, so the resulting wetlaid nonwoven fabric has a water contact angle of less than 25 ° on the first surface and poor heat sealability. In Comparative Example 4, the drying temperature was in the range of [Tmf - 41°C] or higher and [Tmf - 25°C] or lower, but since the fiber web contained 80% by mass or more of P3HA-based fibers and 20% by mass or less of cellulose-based fibers relative to the total mass of the cellulose-based fibers and P3HA-based fibers, the water contact angle of the first surface of the obtained wetlaid nonwoven fabric was less than 25° and the heat sealability was poor.

[0103] The present invention is not particularly limited, and may include, for example, one or more of the following embodiments.

[0104] [1] A nonwoven fabric comprising cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, wherein one surface of the nonwoven fabric has a water contact angle of 25° to 90°. [2] The nonwoven fabric according to [1], wherein the content of the cellulose-based fibers is 30% by mass to 70% by mass, based on the total mass of the cellulose-based fibers and the poly(3-hydroxyalkanoate)-based fibers. [3] The nonwoven fabric according to [1] or [2], wherein the poly(3-hydroxyalkanoate)-based resin is a copolymer containing 3-hydroxybutyrate units and other hydroxyalkanoate units. [4] The nonwoven fabric according to any one of [1] to [3], wherein the content of the 3-hydroxybutyrate units is more than 24 mol% and 99 mol% or less, based on the total 100 mol% of the 3-hydroxybutyrate units and the other hydroxyalkanoate units. [5] The nonwoven fabric according to any one of [1] to [4], which is a staple fiber nonwoven fabric. [6] The nonwoven fabric according to any one of [1] to [5], which is a wetlaid nonwoven fabric. [7] The nonwoven fabric according to any one of [1] to [6], which is a mixed fiber nonwoven fabric. [8] A laminated sheet comprising a layer containing nonwoven fabric I and a layer containing nonwoven fabric II, wherein the nonwoven fabric I is the nonwoven fabric according to any one of [1] to [7], and 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 greater than the content of the cellulosic fibers in the nonwoven fabric I. [9] The laminated sheet according to [8], wherein the content of the cellulosic fibers in the nonwoven fabric II is 40% by mass or more and 100% by mass or less, based on the total mass of the cellulosic fibers and the poly(3-hydroxyalkanoate) fibers.

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

[11] A food product comprising the nonwoven fabric according to any one of [1] to [7] or the laminated sheet according to any one of [8] to

[10] .

[12] The food product according to

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

[13] A method for producing a nonwoven fabric, comprising: Step I obtaining a wet sheet containing cellulosic fibers and poly(3-hydroxyalkanoate) fibers containing a poly(3-hydroxyalkanoate) resin; and Step II drying the wet sheet in a dryer, wherein the wet sheet contains more than 20% by mass but less than 80% by mass of poly(3-hydroxyalkanoate) fibers and more than 20% by mass but less than 80% by mass of cellulosic fibers relative to the total mass of the cellulosic fibers and the poly(3-hydroxyalkanoate) fibers, and wherein the drying temperature in Step II is from [Tmf - 41°C] to [Tmf - 25°C], where Tmf is the melting point of the poly(3-hydroxyalkanoate) fibers.

[14] The method for producing a nonwoven fabric according to

[13] , wherein the dryer is a Yankee dryer.

Claims

1. A nonwoven fabric comprising cellulose-based fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, wherein the water contact angle on one surface of the nonwoven fabric is 25° or more and 90° or less.

2. The nonwoven fabric according to claim 1, wherein the content of the cellulosic fibers is 30% by mass or more and 70% by mass or less of 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) resin is a copolymer containing 3-hydroxybutyrate units and other hydroxyalkanoate units.

4. 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.

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

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

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

8. A laminated sheet comprising a layer containing nonwoven fabric I and a layer containing nonwoven fabric II, wherein said nonwoven fabric I is the nonwoven fabric described in any one of claims 1 to 7, and said nonwoven fabric II contains cellulosic fibers and poly(3-hydroxyalkanoate)-based fibers containing a poly(3-hydroxyalkanoate)-based resin, and the cellulosic fiber content in said nonwoven fabric II is greater than the cellulosic fiber content in said nonwoven fabric I.

9. A laminated sheet as described in claim 8, wherein the content of the cellulose-based fibers in the nonwoven fabric II is 40% 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 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 7.

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 8.

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

15. A method for producing a nonwoven fabric, comprising: Step I obtaining a wet sheet containing cellulosic fibers and poly(3-hydroxyalkanoate) fibers containing a poly(3-hydroxyalkanoate) resin; and Step II drying the wet sheet in a dryer, wherein the wet sheet contains more than 20% by mass but less than 80% by mass of poly(3-hydroxyalkanoate) fibers and more than 20% by mass but less than 80% by mass of cellulosic fibers relative to the total mass of the cellulosic fibers and poly(3-hydroxyalkanoate) fibers, and wherein the drying temperature in Step II is between [Tmf - 41°C] and [Tmf - 25°C], where Tmf is the melting point of the poly(3-hydroxyalkanoate) fibers.

16. The method for producing a nonwoven fabric according to claim 15, wherein the dryer is a Yankee dryer.

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