Biodegradable nonwoven fabric and method for producing the same

Abstract

The problem to be solved by the present invention is to provide a biodegradable nonwoven fabric having biodegradability and excellent flexibility and stretchability, and a method for producing the same. The biodegradable nonwoven fabric of the present invention is a nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin, and is characterized in that the elongation is 50% or more and the elongation recovery rate at 20% elongation is 60% or more.

Description

Technical Field

[0001] The present invention relates to a biodegradable nonwoven fabric containing a biodegradable thermoplastic resin and a method for manufacturing the same.

Background Art

[0002] Adhesives, bandages, etc. used in medical applications and the like need to follow the movement of the skin caused by moving joints and the like. In addition, in order to prevent fraying from the end during use and to obtain sufficient drug efficacy, a high bulk density is required.

[0003]

[0004] As a nonwoven fabric that can be used for such applications, Patent Document 1 discloses a long fiber nonwoven fabric composed of long fibers of a two-component composite spinning containing polyethylene terephthalate and a copolyester, having an apparent density of 0.1 g / cc or more and an elongation recovery rate of 10% of 65% or more.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] ​However, biodegradable resins are generally hard, and their uses are often limited to a range where flexibility and stretchability are not required as application characteristics. Also, for the purpose of imparting flexibility, when making a nonwoven fabric using a soft resin during raw material selection, the yarn strength tends to be low, and yarn breakage is likely to occur during yarn stretching in the production process, so problems with productivity are likely to arise.

[0007] In addition, in the nonwoven fabric disclosed in Patent Document 2, a biodegradable resin with a relatively low melt viscosity is used, which has favorable melt characteristics for enhancing moldability. However, in that case, the recovery rate during elongation, which is in a trade-off relationship with moldability, is poor. For example, there was room for improvement in stretchability for use as an adhesive material. Also, when using a biodegradable resin with a relatively low melt viscosity, yarn breakage is likely to occur during stretching, and it was necessary to further adjust the manufacturing conditions from the viewpoints of productivity and the like.

[0008] As described above, conventionally, nonwoven fabrics having followability and excellent recovery rate during elongation were known, but they were not biodegradable nonwoven fabrics (Patent Document 1). Also, while nonwoven fabrics with good moldability obtained using biodegradable resins are known (Patent Document 2), biodegradable nonwoven fabrics with excellent flexibility and stretchability have not been conventionally known.

[0009] The problem to be solved by the present invention is to provide a biodegradable nonwoven fabric having biodegradability and excellent flexibility and stretchability, and a manufacturing method thereof.

Means for Solving the Problem

[0010] The inventors of the present invention conducted intensive research to solve the above problems. As a result, by using a biodegradable thermoplastic resin with a relatively high melt viscosity and adopting favorable manufacturing conditions according to its melt characteristics, it was found that a biodegradable nonwoven fabric having biodegradability and excellent flexibility and stretchability can be stably obtained, and the present invention was completed.

[0011] That is, the present invention provides the following.

[0012] [1] A biodegradable nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin, wherein the elongation of the nonwoven fabric is 50% or more, and the elongation recovery rate before and after elongation at 20% elongation of the nonwoven fabric is 60% or more.

[0013] [2] The biodegradable nonwoven fabric according to [1], wherein the biodegradable thermoplastic resin is an aromatic-containing polyester.

[0014] [3] The biodegradable nonwoven fabric according to [1] or [2], wherein the crystal melting enthalpy of the biodegradable thermoplastic resin is in the range of 9 J / g or more and 50 J / g or less.

[0015] [4] The biodegradable nonwoven fabric according to any one of [1] to [3], wherein the melt flow rate of the biodegradable thermoplastic resin is in the range of 0.3 g / 10 min or more and 50.0 g / 10 min or less under the conditions of a temperature of 190 °C and a load of 2.16 kg.

[0016] [5] The biodegradable nonwoven fabric according to any one of [1] to [4], wherein the biodegradable thermoplastic resin has a melting point in the range of 70 °C or more and 200 °C or less.

[0017] [6] The biodegradable nonwoven fabric according to any one of [1] to [5], wherein the biodegradable thermoplastic resin contains, in a total amount of 70 mol% or more, an adipic acid component, a terephthalic acid component, and a butanediol component in 100 mol% of all components.

[0018] [7] The biodegradable nonwoven fabric according to any one of [1] to [6], wherein the biodegradable thermoplastic resin contains polybutylene adipate terephthalate.

[0019] [8] The biodegradable nonwoven fabric according to any one of [1] to [7], which is not subjected to mechanical entanglement treatment.

[0020] A method for manufacturing a biodegradable nonwoven fabric according to any one of [1] to [8] in [9], which comprises: Step A of discharging a molten biodegradable thermoplastic resin from a spinneret, cooling and solidifying it, and then pulling and stretching it with an ejector to form long fibers; Step B of collecting the long fibers obtained in Step A to form a long fiber web; and Step C of thermocompression bonding the long fiber web. A method for manufacturing a biodegradable nonwoven fabric, characterized by comprising these steps.

Advantages of the Invention

[0021] According to the present invention, it is possible to provide a nonwoven fabric having biodegradability and excellent flexibility and stretchability. Since the elongation at break is 50% or more, when used as an adhesive or a bandage, etc., it will not tear even when gently pulled, and it can have sufficient followability as a use because it easily deforms. Further, since the recovery rate at 20% elongation is 60% or more, it has excellent stretchability and a good feeling of use when used as an adhesive or a bandage, etc.

[0022] In order to obtain a nonwoven fabric having excellent flexibility and stretchability, it is effective to use a biodegradable thermoplastic resin having a relatively high melt viscosity and adopt preferable manufacturing conditions according to its melt characteristics. Although the details of the reason are unknown, it is presumed that by using a biodegradable thermoplastic resin having a higher molecular weight than before, appropriate crystal orientation occurs in the process of spinning and stretching, etc.

[0023] Hereinafter, embodiments of the present invention will be described in detail.

Modes for Carrying Out the Invention

[0024] The biodegradable nonwoven fabric of the present invention is composed of fibers containing a biodegradable thermoplastic resin. The biodegradable thermoplastic resin preferably has a crystal melting enthalpy of 9 J / g or more. By having a crystal melting enthalpy of 9 J / g or more, the recovery property during elongation of the biodegradable nonwoven fabric can be improved. The crystal melting enthalpy is more preferably 14 J / g or more, still more preferably 18 J / g or more, still more preferably 19 J / g or more, even more preferably 20 J / g or more, and particularly preferably 21 J / g or more. On the other hand, the crystal melting enthalpy is preferably 50 J / g or less. Thereby, the flexibility of the biodegradable nonwoven fabric is improved, and the generation of noise during compression and recovery can be reduced. The crystal melting enthalpy can be more preferably 28 J / g or less, and still more preferably 26 J / g or less.

[0025] The crystal melting enthalpy (J / g) of the biodegradable thermoplastic resin can be determined from the integrated value of the endothermic peak (melting peak) of the endothermic and exothermic curve measured at a heating rate of 20 °C / min under a nitrogen atmosphere using a differential scanning calorimeter with a sample mass of 2.0 mg ± 0.1 mg. The integrated value is obtained by taking the point where the curve related to the endothermic peak (melting peak) starts to deviate from the baseline on the low-temperature side as the starting point, the point where it starts to contact the baseline on the high-temperature side as the end point, drawing a straight line connecting the starting point and the end point, and integrating the portion surrounded by the straight line and the curve.

[0026] The weight average molecular weight (g / mol) of the biodegradable thermoplastic resin is preferably 35,000 or more. Thereby, the recovery property during elongation after compression can be improved. The weight average molecular weight is more preferably 37,000 or more, and still more preferably 40,000 or more. Also, it is preferably 150,000 or less. When it is 150,000 or less, the flexibility can be improved. Further, when the weight average molecular weight is 120,000 or less, the polymer melt viscosity can be reduced. The weight average molecular weight is more preferably 120,000 or less. The weight average molecular weight can be determined by gel permeation chromatography (GPC) or the like.

[0027] The melt flow rate (MFR) of the biodegradable thermoplastic resin can be in the range of 0.3 g / 10 min to 50 g / 10 min under the conditions of a temperature of 190 °C and a load of 2.16 kg. Preferably, it is 0.4 g / 10 min to 20 g / 10 min, and more preferably 0.5 g / 10 min to 15 g / 10 min. Even more preferably, it is 3 g / 10 min to 13 g / 10 min, even more preferably 6 g / 10 min to 12 g / 10 min, and even more preferably 8 g / 10 min to 10 g / 10 min. When fiberizing thermoplastic resins including the spunbond method, a thermoplastic resin with an MFR of around 100 g / 10 min is often used due to the ease of yarn forming during melting. However, in the case of such an MFR, the yarn strength is often weak during the fiberization of the biodegradable thermoplastic resin, and the yarn is likely to break during the stretching process. Therefore, especially when the MFR is 15 g / 10 min or less, the single yarn strength of the nonwoven fabric is improved, and there is a tendency to prevent yarn breakage during the stretching process. When it is 10 g / 10 min or less, the yarn breakage property tends to be better. Also, when the MFR is 0.3 g / 10 min or more, the viscosity during melting does not become too high, and it becomes easy to form into yarn. The MFR of the biodegradable thermoplastic resin can be measured by the method described in the examples below. The MFR of the biodegradable thermoplastic resin can be adjusted by the type, copolymer composition, molecular weight, melting point, etc. of the biodegradable thermoplastic resin.

[0028] The melting point of the biodegradable thermoplastic resin is preferably 70 °C to 200 °C. More preferably, it is 100 °C to 170 °C, and even more preferably 110 °C to 130 °C. When the melting point is less than 70 °C, the single yarn strength of the fibers constituting the nonwoven fabric decreases, and yarn breakage is likely to occur in the stretching process. On the other hand, when the melting point exceeds 200 °C, the ratio of the hard segment in the molecular structure becomes too high, and the flexibility and stretchability of the nonwoven fabric are likely to be lost.

[0029] Examples of the biodegradable thermoplastic resin include polylactic acid, polylactic acid / polycaprolactone copolymer, polylactic acid / polyether copolymer, polyethylene terephthalate succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyglycolic acid, polycaprolactone, polyvinyl alcohol, cellulose acetate, etc. Among them, aromatic-containing polyesters such as polyethylene terephthalate succinate and polybutylene adipate terephthalate are more preferred, and polybutylene adipate terephthalate-based resins are particularly preferred. When the biodegradable thermoplastic resin is an aromatic-containing polyester, better stretchability can be obtained. When the biodegradable thermoplastic resin is a copolyester containing structural units derived from an aromatic carboxylic component and an aliphatic carboxylic component, even better stretchability can be obtained. When the biodegradable thermoplastic resin contains a polybutylene adipate terephthalate-based resin, it may also contain the above-mentioned other biodegradable thermoplastic resins. For details of these, reference may be made to the positive list of Classification No. A-1 of Green Plastics (biodegradable plastics) of the Japan Bioplastics Association. The fibers constituting the biodegradable nonwoven fabric may contain resins other than the biodegradable thermoplastic resin. Examples of such resins include thermoplastic resins such as polyurethane and polyester.

[0030] In addition, the classification number of the Green Plastics (biodegradable plastics) of the Japan Bioplastics Association is as follows according to the positive list (Ver.2023.4 (Sep.)) of Category A-1: Hydroxyl group-modified starch manufactured by Kuraray, Mater-Bi® NF01U and Mater-Bi® ZF03U / A manufactured by GSI Creos (Novamont), which are starch polyesters, cellulose acetate (diacetate) manufactured by Daicel, NatureWorks 2000 series, 3000 series, 4000 series, 6000 series, 7000 series, 8000 series, Ingeo® 5061A, and Ingeo® 5061B manufactured by NatureWorks Japan. Furthermore, as for polylactic acid, Kaneparl® B100 manufactured by Kaneka, Bioloop® BE-400, BE-410, HYD-006 manufactured by Toray Industries, REVODE® 100 series, 200 series manufactured by Daisan Pharmaceutical (Zhejiang Hisun Biomaterials Co., Ltd.), PLA manufactured by Pliith Biotechnology, Luminy L-series, Luminy LX-series, Luminy D-series manufactured by TotalEnergies Corbion, CKBP-PLLA-F01 manufactured by Mitokharness, FY200 series, FY400 series, FY600 series, FY800 series manufactured by Highchem (Anhui Fengyuan Futailai Polylactic Acid Co., Ltd.) are listed. As for the polylactic acid / polycaprolactone copolymer, Bioloop® BE-450, HYD-306, BE-910 manufactured by Toray Industries, AONILEX® manufactured by Kaneka as poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), Cresage® and Credax® manufactured by Kreha as polyglycolic acid, EcoDear® L4E6 series manufactured by Toray as the polylactic acid / polyether copolymer, Placcel® H1P, H5C, H8C manufactured by Daicel, Capa6500, Capa6500D, Capa6800, Capa6800D manufactured by Invista Japan as polycaprolactone, PHACT manufactured by CJ CHEIL JEDANG as poly(3-hydroxybutyrate-co-4-hydroxybutyrate). TMA1000P, PHACT TM S1000P, Mater - Bi® CS series manufactured by Novamont (GSI Creos) which is a copolymer of butanediol and long - chain dicarboxylic acid, EcoFlex® manufactured by BASF Japan which is polybutylene adipate / terephthalate, EcoFlex® FS manufactured by BASF Japan as an aliphatic - aromatic polyester, Origo - BiES01G manufactured by Novamont (GSI Creos) as polytetramethylene adipate - co - terephthalate, EastarBio, Ultra, BioPBS FZ71, BioPBS FZ91, BioPBS FZ78 manufactured by PTT MCC as polybutylene succinate, TUNHEPBS manufactured by BLUERIDGE, ECO - B manufactured by Changchun Japan. As polybutylene succinate adipate, BioPBS FD92 manufactured by PTT MCC, A400 (ECOPON DKD1024) manufactured by KINGFA as polybutylene adipate terephthalate, TUNHEPBAT manufactured by BLUERIDGE, CKBP - PBAT - 01 manufactured by Mitokharnes, ECO - A manufactured by Changchun Japan, HF101 manufactured by Haike Mu (Zhejiang Huafeng Environmental Protection Materials), Ecoworld Biodegradable Polymer manufactured by JinHuiZhaoLong High - Tech, Biodegradable Resin KHB21 manufactured by Kanghui New Material Technology, HF901 manufactured by Chori as polypropylene carbonate, As polyvinyl alcohol, Gosenol® manufactured by Mitsubishi Chemical, Gosenex® T, Gosenex® WO, Nichigo® G polymer, fully saponified Kuraray Poval® (registered trademark), medium - saponified Kuraray Poval® (registered trademark), partially saponified Kuraray Poval® (registered trademark), low - saponified Kuraray Poval® (registered trademark), Kuraray Exceval® (registered trademark) are mentioned.

[0031] As a monomer for synthesizing a biodegradable thermoplastic resin, a petroleum-derived monomer may be used, but it is preferable to use a biomass-derived monomer because it can reduce the environmental load. For biomass-derived monomers, for example, monomers described in the positive list of the classification number A (biomass plastic) of the Japan Bioplastics Association may be referred to.

[0032] In 100 mol% of all components constituting the biodegradable thermoplastic resin, the total content of the adipic acid component, terephthalic acid component, and butanediol component is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, still more preferably 95 mol% or more, and particularly preferably 99 mol% or more. In 100 mol% of all components constituting the biodegradable thermoplastic resin, it is more preferably 100 mol%. Further, the fibers constituting the biodegradable nonwoven fabric preferably consist only of the biodegradable thermoplastic resin in terms of biodegradability and environmental friendliness.

[0033] The polybutylene adipate terephthalate-based resin is a biodegradable resin and is a copolymer of adipic acid, terephthalic acid, and butanediol. Since the polybutylene adipate terephthalate-based resin is a biodegradable resin, it is expected to be a solution to the problems of waste disposal and microplastics. Adipic acid, terephthalic acid, and butanediol do not need to be copolymerized simultaneously and may be copolymerized in multiple steps.

[0034] The molar ratio (adipic acid component / terephthalic acid component) of the adipic acid component and terephthalic acid component in the polybutylene adipate terephthalate-based resin is preferably 35 / 65 or more and 60 / 40 or less, more preferably 40 / 60 or more and 55 / 45 or less, from the viewpoint of enhancing the elongation recovery rate at 20% elongation of the nonwoven fabric while exhibiting biodegradability.

[0035] When synthesizing polybutylene adipate terephthalate resin, in addition to adipic acid, terephthalic acid, and butanediol, a small amount of other copolymerization components may be added. Examples of other copolymerization components include dicarboxylic acids other than terephthalic acid and adipic acid, and modifiers for the purpose of chain extension or end capping. These may be used alone or in combination of two or more.

[0036] Examples of other dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, etc. These may be used alone or in combination of two or more.

[0037] Examples of the modifier include polyisocyanate compounds, glycol compounds, etc. Examples of polyisocyanate compounds include diisocyanate compounds. Examples of diisocyanate compounds include hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, carbodiimide-modified MDI, polymethylene polyphenyl polyisocyanate, etc. These may be used alone or in combination of two or more. Examples of glycol compounds include diols other than butanediol and polyalkylene glycols. Examples of other diols include methanediol, ethanediol, propanediol, pentanediol, hexanediol, etc. Examples of polyalkylene glycols include polymethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol (polytetramethylene glycol), etc. These may be used alone or in combination of two or more.

[0038] Examples of polybutylene adipate terephthalate resins include biodegradable synthetic polymer compounds listed on the positive list of the Japan Bioplastics Association's GreenPla (biodegradable plastic) classification number A-1. Specific examples include ECO-A20 manufactured by CHANG CHUN PLASTICS CO., LTD., Ecoflex (registered trademark) manufactured by BASF Japan Ltd., EastarBio GP and EastarBo Ultra manufactured by GSI Creos Co., Ltd. (Novmont), A40 (ECPONDKD1024) manufactured by KINGFA Co., Ltd., and TUNHEP BATTH-801T manufactured by XINJIANG BLUERIDGETUNHE CHEMICAL INDUSTRY JOINTSTOCK CO., LTD.

[0039] The biodegradable nonwoven fabric is composed of fibers containing a biodegradable thermoplastic resin. The fibers constituting the biodegradable nonwoven fabric preferably contain 80% by mass or more of the biodegradable thermoplastic resin, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

[0040] The shape of the fibers constituting the biodegradable nonwoven fabric is not particularly limited, but may have a circular, flat, C-shaped, Y-shaped, V-shaped or other irregular cross section, preferably a circular cross section, and may also have a sea-island structure, a sheath-core structure, or a split fiber structure.

[0041] The fibers constituting the biodegradable nonwoven fabric may further contain one or more other resins, flame retardants, inorganic fillers, softeners, plasticizers, pigments, antistatic agents, etc., depending on the purpose.

[0042] The fiber diameter of the fibers constituting the biodegradable nonwoven fabric is preferably 5 to 60 μm, more preferably 10 μm to 50 μm, and even more preferably 12 μm to 40 μm. When the fiber diameter is 5 μm or more, the spinnability in the spunbond method becomes better, and stable production becomes possible. Further, when the fiber diameter is 60 μm or less, the uniformity of the nonwoven fabric is less likely to decrease, and when used as an adhesive, bleeding of the medicinal ingredient can be suppressed.

[0043] The basis weight and thickness of the biodegradable nonwoven fabric are not particularly limited, but the basis weight can be in the range of 10 to 200 g / m 2 and the thickness can be in the range of 0.05 to 6.0 mm.

[0044] The apparent density of the biodegradable nonwoven fabric is preferably 0.1 g / cc or more, more preferably 0.11 g / cc or more, and even more preferably 0.13 g / cc or more. Further, although the larger the apparent density is, the more preferable it is, for example, it can be 0.3 g / cc or less, 0.28 g / cc or less, etc. Since the apparent density is 0.1 g / cc or more, when used as an adhesive or a bandage, even if rubbing occurs with clothing or the like, it is difficult to receive friction, and it is possible to prevent fraying during use.

[0045] It is preferable that the biodegradable nonwoven fabric is not subjected to mechanical entanglement treatment. Examples of the mechanical entanglement treatment include entanglement treatment by the needle punching method or the water punching method. When the mechanical entanglement treatment is not performed, it is preferable in terms of being able to be manufactured at low cost. Further, it is preferable in terms of being able to avoid risks such as the mixing of needle needles that may occur when the needle punching method is adopted. Further, the water punching method uses a large amount of water and requires a huge amount of energy. Therefore, from the viewpoints of environmental conservation and energy saving, it is preferable that the mechanical entanglement treatment is not performed.

[0046] The biodegradable nonwoven fabric can have a stress at 5% elongation of 0.1 to 100 (N / 2.5 cm), preferably 0.3 to 2.0 (N / 2.5 cm). Particularly when it is 1.0 (N / 2.5 cm) or less, there is less feeling of stiffness, and the usability when used as a base fabric for an adhesive material is good. In this specification, "the stress at 5% elongation is 0.1 (N / 2.5 cm) or more" means that the stress at 5% elongation in the MD (machine direction) is 0.1 (N / 2.5 cm) or more and the stress at 5% elongation in the CD (cross direction) is 0.1 (N / 2.5 cm) or more.

[0047] The biodegradable nonwoven fabric can have a mechanical strength of 1 to 200 (N / 2.5 cm), preferably 5 to 100 (N / 2.5 cm). Particularly when it is 8 (N / 2.5 cm) or more, it is possible to suppress easy breakage when used as a base fabric for an adhesive material. In this specification, "the mechanical strength is 1 (N / 2.5 cm) or more" means that the mechanical strength in the MD (machine direction) is 1 (N / 2.5 cm) or more and the mechanical strength in the CD (cross direction) is 1 (N / 2.5 cm) or more.

[0048] The biodegradable nonwoven fabric has an elongation of 50% or more. An elongation of 60% or more is preferable, more preferably 70% or more, and even more preferably 100% or more. When the elongation is 50% or more, when used as an adhesive or a bandage, etc., it does not tear even when gently pulled, and it can have sufficient followability as a use by easily deforming. Also, the elongation is preferably 500% or less, more preferably 300% or less. In this specification, "the elongation is 50% or more" means that the elongation in the MD (machine direction) is 50% or more and the elongation in the CD (cross direction) is 50% or more. To improve the elongation of the biodegradable nonwoven fabric, it is effective to use a biodegradable thermoplastic resin having a relatively small melt flow rate (MFR) and adopt preferable manufacturing conditions according to its melting characteristics.

[0049] The biodegradable nonwoven fabric has an elongation recovery rate before and after elongation at 20% elongation of 60% or more, preferably 70% or more, more preferably 80% or more. Also, the elongation recovery rate at 20% elongation is preferably as large as possible, but can be, for example, 99.5% or less, 99.0% or less, etc. Since the elongation recovery rate at 20% is 60% or more, it has excellent stretchability and a good feel when used as an adhesive or a bandage. For example, when attached to a joint such as an elbow, it can follow the movement of the skin at the bent part and suppress the generation of wrinkles. As a result, peeling caused by the location of the wrinkles can be prevented. In this specification, "the elongation recovery rate at 20% is 60% or more" means that the elongation recovery rate at 20% in the MD (machine direction) is 60% or more and the elongation recovery rate at 20% in the CD (cross direction) is 60% or more. To improve the elongation recovery rate at 20% of the biodegradable nonwoven fabric, it is effective to use a biodegradable thermoplastic resin with a relatively small melt flow rate (MFR) of the biodegradable thermoplastic resin and adopt preferable manufacturing conditions according to its melting characteristics.

[0050] The biodegradable nonwoven fabric can have a stiffness-flexibility of 5 to 150, preferably 10 to 100, more preferably 12 to 80, and even more preferably 13 to 50. In particular, when the stiffness-flexibility is 50 or less, there is less a feeling of stiffness when used as a base fabric for an adhesive material, and the feel when used as a base fabric for an adhesive material is good.

[0051] The manufacturing method of the biodegradable nonwoven fabric is not limited, but known spunbond methods, meltblown methods, airlaid methods, card methods, papermaking methods, etc. can be adopted. The biodegradable nonwoven fabric of this embodiment is preferably integrated by adhesion, and as the adhesion method, embossing, thermal bonding, etc. can be used. Since it can be produced efficiently and the fuzzing etc. after molding can also be suppressed, a long fiber nonwoven fabric is preferable, and more preferably it is produced by the spunbond method.

[0052] When using the spunbond method, the resin is heated and melted, discharged from a spinneret, the obtained spun yarn is cooled using a known cooling device, and drawn and thinned by a suction device such as an air sucker. Subsequently, after the yarn group discharged from the suction device is opened, it is deposited on a conveyor to form a web. Next, the web formed on this conveyor is partially thermocompression-bonded using a partial thermocompression-bonding device such as a heated embossing roll, whereby a spunbond nonwoven fabric is obtained. The nonwoven fabric obtained by the spunbond method has physical properties such as strong fabric strength and no shedding of short fibers due to damage of the bonding part, and also has low cost and high productivity.

[0053] The biodegradable nonwoven fabric can be manufactured, for example, by a manufacturing method having the following steps A to C. Step A of discharging the molten thermoplastic resin from a spinneret, cooling and solidifying it, and then drawing and stretching it with an ejector to form fibers, step B of collecting the long fibers obtained in step A to form a long fiber web, and step C of thermocompression-bonding the long fiber web, whereby a nonwoven fabric is obtained.

[0054] <Step A> In the manufacturing method of the biodegradable nonwoven fabric according to the present embodiment, first, the molten thermoplastic resin is discharged from a spinneret, cooled and solidified, and then drawn and stretched with an ejector to form fibers (step A).

[0055] At this time, it is preferable to adjust the spinning temperature and spinning speed when discharging the molten biodegradable thermoplastic resin from the spinneret according to the MFR (melting characteristics) of the biodegradable thermoplastic resin. For example, when using a biodegradable thermoplastic resin having a smaller MFR value than before, it is effective to increase the spinning temperature or reduce the spinning speed.

[0056] This step A can be carried out using a spinning machine including a conventionally known spunbond spinning machine.

[0057] In the step A, it is preferable to spin from a spinneret having an orifice diameter of 0.1 to 0.5 mm and supply dry air at a pressure (jet pressure) of 0.5 to 4.0 kg / cm 2 to perform stretching. The orifice diameter of the spinneret is more preferably 0.15 to 0.5 mm, and even more preferably 0.18 to 0.45 mm. By controlling the orifice diameter within the above range, it becomes easier to control the fiber diameter. Further, by controlling the supply pressure (jet pressure) of the dry air within the above range, it becomes easier to control the spinning speed constantly and to dry appropriately.

[0058] <Step B> Next, the long fibers obtained in the step A are collected to form a long fiber web (step B). For example, the long fibers may be opened and collected on a lower conveyor to form a long fiber web.

[0059] <Step C> Next, the long fiber web obtained in the step B is thermocompression bonded (step C). The thermocompression bonding is performed within a temperature range in which the long fiber web does not shrink. Thereby, it becomes possible to convey suitably. As the temperature at the time of the thermocompression bonding, it is preferably at a temperature 10°C or more lower than the melting point of the resin of the nonwoven fabric, the linear pressure is preferably 5 to 100 N / mm, more preferably 20 to 80 N / mm, and the pressure bonding area ratio is preferably 3 to 50%, more preferably 6 to 40%, and thermocompression bonding can be performed. By performing thermocompression bonding within an appropriate range, it becomes possible to achieve both the flexibility and stretchability of the nonwoven fabric and the pressure bonding.

Example

[0060] Hereinafter, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited to the examples.

[0061] Examples 1 to 5 and Comparative Examples 1 to 5 below were measured based on the following methods. The properties such as physical properties in this specification are specifically measured by the following methods.

[0062] (Intrinsic viscosity) Weighed 0.1 g of the resin, dissolved it in 25 ml of a mixed solvent of phenol / tetrachloroethane (60 / 40 (weight ratio)), measured it 3 times at 30 °C using an Ostwald viscometer, and obtained the average value.

[0063] (Specific gravity) Prepared a density gradient liquid using calcium nitrate tetrahydrate in a density gradient tube. 1.20 - 1.5 g / cm 3 Using the specific gravity float range, the fiber after jet stretching was put into the density gradient tube, allowed to float stably for 4 hours or more, the memory of the floating position was read, and the specific gravity was obtained from the calibration curve of the float.

[0064] (Crystal melting enthalpy) Weighed 2.0 mg ± 0.1 mg of the resin, used a differential scanning calorimeter Discovery DSC25 manufactured by TA Instruments, and measured the endothermic / exothermic curve under the conditions of a heating rate of 20 °C / min and a nitrogen atmosphere. The crystal melting enthalpy (J / g) was obtained from the integral value of the endothermic peak (melting peak). Specifically, the integral value of the endothermic peak (melting peak) was obtained by starting from the point where the curve related to the endothermic peak (melting peak) begins to deviate from the baseline on the low-temperature side as the starting point, ending at the point where it begins to contact the baseline on the high-temperature side, drawing a straight line connecting the starting point and the ending point, and integrating the part surrounded by the straight line and the curve. The above operation was performed 3 times to obtain the average value (n = 3) of the crystal melting enthalpy. Also, the starting point was defined as the melting onset temperature (°C).

[0065] (Melting point) Weighed the resin so that the mass was 2.0 mg ± 0.1 mg. Then, using a differential scanning calorimeter (Discovery DSC25 manufactured by TA Instruments), the endothermic peak (melting peak) temperature was obtained from the DSC curve measured at a heating rate of 20 °C / min under a nitrogen atmosphere. The above operation was performed 3 times to obtain the average value (n = 3) of the melting point.

[0066] (Melt flow rate (MFR)) After drying the resin in vacuo at 80 °C for 2 hours or more, the melt flow rate (MFR) was quickly measured so as to contain as little moisture in the air as possible. Using a melt indexer F-F01 machine manufactured by Toyo Seiki Seisakusho Co., Ltd., the melt flow rate was measured in accordance with ISO 1133. The measurement temperature was 190 °C and the load was 2.16 kg. This operation was performed 3 times to obtain the average value (n = 3) of the melt flow rate.

[0067] (Weight average molecular weight) The resin was dissolved in a small amount of chloroform to obtain a sample solution. The sample solution was further diluted with chloroform to adjust the concentration of the sample solution to 0.05 mass%. After filtering with a 0.2 μm membrane filter, GPC analysis of the obtained solution was performed under the following conditions. The molecular weight was calculated in terms of standard polystyrene.

[0068] Apparatus: TOSOH HLC-8320GPC Column: TSKgel Super HM-H × 2 + TSKgel Super H2000 (TOSOH) Solvent: Chloroform

[0069] (Basis weight) In accordance with JIS L1913(2010) 6.2, the mass per unit area was measured.

[0070] (Thickness, apparent density (bulk density)) Based on the above basis weight and thickness determined in accordance with JIS-L1913(2010) 6.2 and 6.1, the weight per 1 cm 3 was converted to obtain the bulk density. Specifically, the thickness was measured using a thickness gauge with a terminal of 0.5 g / cm 2 and the bulk density was obtained by dividing the basis weight by the thickness.

[0071] (Fiber diameter) Five arbitrary points of the sample (long fiber web before thermocompression) were selected, and the diameter of single fibers was measured with n = 20 using an optical microscope, and the average value was obtained.

[0072] (Fineness (dtex)) Five points were selected at arbitrary locations on the sample (long fiber web before thermocompression bonding), and the single fiber diameter was measured 20 times using an optical microscope to obtain the average single fiber diameter. Five fibers at the same location were taken out, and the specific gravity of the fibers was measured 5 times using a density gradient tube to obtain the average specific gravity. Then, the fineness [dtex], which is the fiber weight per 10,000 m, was obtained from the single fiber cross-sectional area determined from the average single fiber diameter and the average specific gravity.

[0073] (Spinning speed (m / min)) The spinning speed V (m / min) was determined based on the following formula from the above fineness T (dtex) and the set single-hole discharge amount Q (g / min). V = (10000 × Q) / T

[0074] (Stress at 5% elongation) A 25 × 100 mm sample (non-woven fabric) was prepared. Using a constant speed elongation type tensile testing machine with a self-recording device, it was attached at a grip interval of 50 mm in a state where it was pulled firmly by hand, and the initial load was set to 0.02 N / 25 mm. Then, it was stretched at a tensile speed of 10 mm / min to 5% of the grip interval. The value of the load at this time was determined as the stress at 5% elongation. It was measured 5 times each in the longitudinal and transverse directions, and the second decimal place of the average value was rounded off.

[0075] (Mechanical strength) A 25 × 100 mm sample (non-woven fabric) was prepared. Using a constant speed elongation type tensile testing machine with a self-recording device, it was attached at a grip interval of 50 mm in a state where it was pulled firmly by hand, and the initial load was set to 0.02 N / 25 mm. Then, it was stretched at a tensile speed of 10 mm / min until it broke. The value of the maximum load at this time was determined as the mechanical strength. It was measured 5 times each in the longitudinal and transverse directions, and the first decimal place of the average value was rounded off.

[0076] (Elongation) A 25×100 mm sample (non-woven fabric) was prepared. Using a constant-speed elongation type tensile testing machine equipped with a self-recording device, it was attached at a gripping interval of 50 mm while being pulled firmly by hand, and the initial load was set to 0.02 N / 25 mm. Then, it was stretched at a tensile speed of 10 mm / min until it broke. The value of the maximum elongation rate at this time was determined as the average elongation. Measurements were taken n = 5 times each in the longitudinal and transverse directions, and the first decimal place of the average value was rounded off.

[0077] (20% elongation recovery rate) A 25×100 mm sample (non-woven fabric) was prepared. Using a constant-speed elongation type tensile testing machine equipped with a self-recording device, it was attached at a gripping interval of 50 mm while being pulled firmly by hand, and the initial load was set to 0.02 N / 25 mm. At this time, “(gripping interval) + (length elongated when the initial load was applied)” was defined as L0. Then, it was stretched at a tensile speed of 25 mm / min to 20% of the gripping interval. The length at this time was defined as L1. Then, immediately, the sample length after unloading to the initial load at the same speed was defined as L2. The 20% elongation recovery rate was determined by the following formula. Measurements were taken n = 5 times each in the longitudinal and transverse directions, and the first decimal place of the average value was rounded off. 20% elongation recovery rate (%) = [(L1 - L2) / (L1 - L0)] × 100

[0078] (Stiffness-flexibility) In accordance with JIS L1913 (2000) 6.7.3 (cantilever method), the stiffness-flexibility per unit area was measured.

[0079] (Thread breakage property) In Process A, the thread condition during stretching was visually confirmed, and the number of thread breaks per 5 minutes was judged as follows to evaluate the thread breakage property. 〇: 1 or less breaks / 5 min, △: 2 to 9 breaks / 5 min, ×: 10 or more breaks / 5 min

[0080] (Elasticity) The stretchability of the nonwoven sheet that had passed through Process C was evaluated by determining the recovery rates at 20% elongation in the longitudinal and transverse directions, respectively, as follows. 〇: The recovery rates at 20% elongation in both the longitudinal and transverse directions are 60% or more. △: Either of the recovery rates at 20% elongation in the longitudinal and transverse directions is 60% or more. ×: The recovery rates at 20% elongation in both the longitudinal and transverse directions are less than 60%.

[0081] (Biodegradability) It was determined whether the resin constituting the nonwoven sheet retained biodegradable properties. 〇: The substance name (resin name) is listed in the positive list of Classification No. A-1 of Green Pla (biodegradable plastic) of the Japan Bioplastics Association. ×: The substance name (resin name) is not listed in the positive list of Classification No. A-1 of Green Pla (biodegradable plastic) of the Japan Bioplastics Association.

[0082] (Example 1) Polybutylene adipate terephthalate shown in Table 1 (MFR: 4 g / min, melting point: 120°C, crystal melting enthalpy: 14 J / g, molar ratio (adipic acid component / terephthalic acid component) = 52.5 / 47.5) (abbreviated as PBAT) was melted and kneaded using a single-screw extruder, and then extruded at a discharge rate of 0.5 g / min·Hole and a spinning temperature of 230°C by the spunbond method, and the filament group was drawn by a high-speed air flow drawing device using an air jet (Process A), and these were deposited on a moving collection surface to prepare a biodegradable long fiber web (circular cross-section) (Process B).

[0083] Next, using a pair of embossing rolls consisting of a roll with an uneven pattern on the surface and a roll with a smooth surface, thermal pressing was performed under the conditions of a crimping area ratio of 12%, a temperature of 80°C for both rolls, and a roll linear pressure of 40 N / mm (Process C), and a biodegradable nonwoven sheet with a basis weight of 70 g / m 2 was obtained.

[0084] (Example 2) The PBAT shown in Table 1 (MFR: 6 g / min, melting point: 150 °C, crystal melting enthalpy: 27 J / g, molar ratio (adipic acid component / terephthalic acid component) = 52.5 / 47.5) was melted and kneaded using a single-screw extruder, and then extruded at a discharge rate of 0.5 g / min·Hole and a spinning temperature of 220 °C by the spunbond method. The filament group was drawn by a high-speed air flow drawing device using an air jet, and these were deposited on a moving collection surface to prepare a biodegradable long fiber web (circular cross-section).

[0085] Next, using a pair of embossing rolls consisting of a roll with an uneven pattern on the surface and a roll with a smooth surface, thermocompression bonding was performed under the conditions of a compression bonding area ratio of 12%, both rolls at a temperature of 110 °C, and a roll linear pressure of 30 N / mm to obtain a biodegradable nonwoven fabric sheet with a basis weight of 70 g / m 2 .

[0086] (Example 3) A biodegradable nonwoven fabric sheet was produced in the same manner as in Example 1, except that the PBAT shown in Table 1 (MFR: 9 g / min, melting point: 120 °C, molar ratio (adipic acid component / terephthalic acid component) = 52.5 / 47.5) was used.

[0087] (Example 4) A biodegradable nonwoven fabric sheet was produced in the same manner as in Example 1, except that the PBAT shown in Table 1 (CHANG CHUN PLASTICS CO., LTD., product number (MFR20): ECO-A20, MFR: 20 g / min, melting point: 120 °C, molar ratio (adipic acid component / terephthalic acid component) = 52.5 / 47.5) was used.

[0088] (Example 5) A biodegradable nonwoven fabric sheet was produced in the same manner as in Example 1, except that the PBAT shown in Table 1 (MFR: 42 g / min, melting point: 120 °C, molar ratio (adipic acid component / terephthalic acid component) = 52.5 / 47.5) was used.

[0089] (Comparative Example 1) Poly(lactic acid) (MFR: 65 g / min, melting point: 170 °C) (abbreviated as PLA) was melted and kneaded in a single-screw extruder, and then extruded at a discharge rate of 0.5 g / min·Hole and a spinning temperature of 210 °C by the spunbond method. The filament group was drawn by a high-speed air flow drawing device using an air jet, and these were deposited on a moving collection surface to prepare a biodegradable long fiber web (circular cross-section).

[0090] Next, using a pair of embossing rolls consisting of a roll with an uneven pattern on the surface and a roll with a smooth surface, thermocompression bonding was performed under the conditions of a compression bonding area ratio of 12%, both rolls at a temperature of 130 °C, and a roll linear pressure of 30 N / mm to obtain a biodegradable nonwoven fabric sheet with a basis weight of 70 g / m 2 .

[0091] (Comparative Example 2) Using a side-by-side nozzle in a two-component spunbond spinning facility, polyethylene terephthalate (intrinsic viscosity (iv value): 0.63) and a copolymerized polyester (a copolymer in which the dicarboxylic acid component is terephthalic acid and the glycol component is 70 mol% ethylene glycol and 30 mol% neopentyl glycol, intrinsic viscosity (iv value): 0.75, Tg: 75 °C) were spun at a mass ratio of 5.5 (polyethylene terephthalate): 4.5 (copolymerized polyester). The spinning was performed at a single-hole discharge rate of 1.0 g / min from a spinneret with an orifice diameter of 0.36 mm. Thereafter, dry air was supplied at a pressure (jet pressure) of 3.5 kg / cm 2 to perform stretching in one step, and the fibers were collected while being opened on the lower conveyor to obtain a long fiber web. Next, the obtained long fiber web was thermocompression bonded. The conditions for thermocompression bonding were a thermocompression bonding roll temperature of 60 °C and a linear pressure of 5 kg / cm. As a result, a long fiber web with a basis weight of 25 g / m 2 was obtained.

[0092] Next, the obtained long fiber web was subjected to a crimping process while being conveyed by six heating rolls. Pressurization was performed using a rubber nip roll. The obtained nonwoven fabric sheet had a basis weight of 100 g / m 2 , a thickness of 0.8 mm, and an apparent density of 0.13 g / cc.

[0093] (Comparative Example 3) Polyethylene terephthalate (intrinsic viscosity (iv value): 0.63) (abbreviated as PET) was melted and kneaded using a single-screw extruder, and then extruded at a discharge rate of 0.5 g / min·Hole and a spinning temperature of 280°C by the spunbond method. The filament group was drawn by a high-speed air jet drawing device, and these were deposited on a moving collection surface to prepare a biodegradable long fiber web (circular cross-section).

[0094] Next, using a pair of embossing rolls consisting of a roll with an uneven pattern on the surface and a roll with a smooth surface, thermocompression bonding was performed under the conditions of a compression bonding area ratio of 12%, both rolls at a temperature of 240°C, and a roll linear pressure of 30 N / mm, to obtain a nonwoven fabric sheet with a basis weight of 70 g / m 2 .

[0095] (Comparative Example 4) Nylon (Ny) 66 (MFR: 100 g / min, melting point: 270°C) was melted and kneaded using a single-screw extruder, and then extruded at a discharge rate of 0.5 g / min·Hole and a spinning temperature of 280°C by the spunbond method. The filament group was drawn by a high-speed air jet drawing device, and these were deposited on a moving collection surface to prepare a biodegradable long fiber web (circular cross-section).

[0096] Next, using a pair of embossing rolls consisting of a roll with an uneven pattern on the surface and a roll with a smooth surface, thermocompression bonding was performed under the conditions of a compression bonding area ratio of 12%, both rolls at a temperature of 240°C, and a roll linear pressure of 30 N / mm, to obtain a nonwoven fabric sheet with a basis weight of 71 g / m 2 .

[0097] (Comparative Example 5) Polybutylene terephthalate (MFR: 100 g / min, melting point: 223°C) (PBT) was melted and kneaded using a single-screw extruder, and then extruded at a discharge rate of 0.5 g / min·Hole and a spinning temperature of 240°C by the spunbond method. The filament group was drawn by a high-speed air jet drawing device, and these were deposited on a moving collection surface to prepare a biodegradable long fiber web (circular cross-section).

[0098] Next, using a pair of embossing rolls consisting of a roll with an uneven pattern on the surface and a roll with a smooth surface, thermocompression bonding was performed under the conditions of a pressure-bonding area ratio of 12%, a temperature of 180 °C for both rolls, and a roll linear pressure of 30 N / mm to obtain a nonwoven fabric sheet with a basis weight of 76 g / m 2 .

[0099] The above results are shown in Table 1 together with the manufacturing conditions.

[0100]

Table 1

Claims

1. A nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin, wherein the biodegradable thermoplastic resin contains, in a total amount of 70 mol% or more, an adipic acid component, a terephthalic acid component, and a butanediol component, based on 100 mol% of all components, wherein the melt flow rate of the biodegradable thermoplastic resin is in the range of 10.0 g / 10 min or less under the conditions of a temperature of 190 °C and a load of 2.16 kg, wherein the elongation of the nonwoven fabric is 70% or more, and the elongation recovery rate before and after elongation at 20% elongation of the nonwoven fabric is 60% or more. A biodegradable nonwoven fabric characterized by the above.

2. The biodegradable nonwoven fabric according to Claim 1, wherein the crystal melting enthalpy of the biodegradable thermoplastic resin is in the range of 9 J / g or more and 50 J / g or less.

3. The biodegradable nonwoven fabric according to Claim 1, wherein the melt flow rate of the biodegradable thermoplastic resin is in the range of 0.3 g / 10 min or more and 10.0 g / 10 min or less under the conditions of a temperature of 190 °C and a load of 2.16 kg.

4. The biodegradable nonwoven fabric according to Claim 1, wherein the biodegradable thermoplastic resin has a melting point in the range of 70 °C or more and 200 °C or less.

5. The biodegradable nonwoven fabric according to Claim 1, wherein the biodegradable thermoplastic resin contains polybutylene adipate terephthalate.

6. The biodegradable nonwoven fabric according to Claim 1, characterized in that no mechanical entanglement treatment is performed.

7. A method for manufacturing a biodegradable nonwoven fabric, which is a method for manufacturing a biodegradable nonwoven fabric according to any one of Claims 1 to 6, comprising: Step A of discharging a molten biodegradable thermoplastic resin from a spinneret, cooling and solidifying it, and then pulling and stretching it with an ejector to form long fibers; Step B of collecting the long fibers obtained in Step A to form a long fiber web; and Step C of thermocompression bonding the long fiber web. A method for manufacturing a biodegradable nonwoven fabric characterized by the above.

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