Biodegradable non-woven fabric and use thereof

Abstract

Provided is a biodegradable non-woven fabric which has biodegradability and has extremely excellent stretchability. A biodegradable nonwoven fabric comprising fibers containing a biodegradable thermoplastic resin is characterized in that an SS curve obtained by elongation in an atmosphere of 30 DEG C does not have a yield point within a displacement range of 0-40 mm.

Description

Technical Field

[0001] The present invention relates to biodegradable nonwoven fabric and use thereof. Background Art

[0002] Biodegradable nonwoven fabrics have traditionally been made from various biodegradable resins, typified by polylactic acid. However, in recent years, with growing awareness of sustainable development, they have been widely used in various fields and applications.

[0003] Patent Document 1 below discloses a biodegradable nonwoven fabric comprising polylactic acid-based latently crimped fibers. The polylactic acid-based latently crimped fibers are a fiber aggregate that is soft, has a sense of expansion, and exhibits practical stretchability. The fibers are parallel-type composite fibers formed by laminating two polymers, one of which is polylactic acid, and the other is a polymer obtained by copolymerizing 1 to 6 mol % of lactic acid with a polyalkylene succinate. The parallel-type composite fibers exhibit latent crimping properties of at least 30 spiral crimps / 25 mm after dry heat treatment at 90°C.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-270407 Summary of the Invention

[0005] Problems to be solved by the invention

[0006] However, the nonwoven fabric described in Patent Document 1 has limited stretchability, and thus a biodegradable nonwoven fabric having higher stretchability has been demanded.

[0007] In view of the above-mentioned conventional technical problems, the technical problem to be solved by the present invention is to provide a biodegradable nonwoven fabric having biodegradability and extremely excellent stretchability.

[0008] Solutions for solving problems

[0009] To solve the above-mentioned technical problems, the present inventors conducted in-depth research and repeated experiments. As a result, they unexpectedly discovered that the stretchability of a biodegradable nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin and having an SS curve obtained by stretching in an atmosphere of 30°C without a yield point in the displacement range of 0 to 40 mm was greatly improved, thereby completing the present invention.

[0010] That is, the present invention is as follows.

[0011] [1] A biodegradable nonwoven fabric characterized in that it is composed of fibers containing a biodegradable thermoplastic resin and that the SS curve obtained by stretching the nonwoven fabric in an atmosphere at 30°C does not have a yield point within the displacement range of 0 mm to 40 mm.

[0012] [2] The biodegradable nonwoven fabric according to [1], wherein the 3% modulus index (N / 30mm / (g / m 2 )) is greater than 0 and less than 0.225.

[0013] [3] The biodegradable nonwoven fabric according to [2], wherein the 3% modulus index in the machine direction (N / 30mm / (g / m 2 )) is less than 0.096.

[0014] [4] The biodegradable nonwoven fabric according to any one of [1] to [3], wherein the proportion of the high motility component measured by pulsed NMR at 30°C is 4.5 to 7.9%.

[0015] [5] The biodegradable nonwoven fabric according to any one of [1] to [4], wherein the Raman spectrum measured by polarized Raman spectroscopy of the fiber with polarized light parallel to the fiber axis is 1612 cm -1 The peak intensity I / / at 1612 cm-1 of the Raman spectrum measured with polarized light perpendicular to the fiber axis -1 The value of the ratio of the peak intensities I⊥ at I / / / I⊥ is 3.2 to 7.9.

[0016] [6] The biodegradable nonwoven fabric according to any one of [1] to [5], wherein the glass transition temperature of the biodegradable thermoplastic resin is 25°C or lower.

[0017] [7] The biodegradable nonwoven fabric according to any one of [1] to [6] above, wherein the biodegradable thermoplastic resin is at least one selected from the group consisting of polybutylene succinate adipate, polybutylene adipate terephthalate, polyhydroxybutyrate valerate, and polyhydroxybutyrate butyrate.

[0018] [8] The biodegradable nonwoven fabric according to [7] above, wherein the biodegradable thermoplastic resin is polybutylene adipate terephthalate.

[0019] [9] The biodegradable nonwoven fabric according to any one of [1] to [8], wherein the biodegradable nonwoven fabric contains at least one layer of spunbonded long fiber nonwoven fabric.

[0020]

[10] The biodegradable nonwoven fabric according to the above [8] is characterized in that the biodegradable nonwoven fabric has a three-layer structure of spunbond long fiber nonwoven fabric / meltblown ultrafine fiber nonwoven fabric / spunbond long fiber nonwoven fabric.

[0021]

[11] A diaper comprising the biodegradable nonwoven fabric according to any one of [1] to

[10] .

[0022]

[12] A wiping cloth comprising the biodegradable nonwoven fabric according to any one of [1] to

[10] .

[0023]

[13] A heating pad comprising the biodegradable nonwoven fabric described in any one of [1] to

[10] .

[0024]

[14] A lightweight packaging material comprising the biodegradable nonwoven fabric described in any one of [1] to

[10] .

[0025] Effects of the Invention

[0026] The biodegradable nonwoven fabric of the present invention is biodegradable and has extremely excellent stretchability, and therefore can be suitably used as diapers, wipes, heating pads, lightweight packaging materials, and the like. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described in detail.

[0028] This embodiment provides a biodegradable nonwoven fabric characterized in that it is composed of fibers containing a biodegradable thermoplastic resin, and the SS curve obtained by stretching the nonwoven fabric in an atmosphere at 30° C. has no yield point in the displacement range of 0 mm to 40 mm.

[0029] The biodegradable nonwoven fabric of this embodiment preferably has no yield point within the displacement range of 0 mm to 40 mm in an SS curve obtained by stretching the biodegradable nonwoven fabric at 30°C. The absence of a yield point within the displacement range of 0 mm to 40 mm allows elastic deformation to occur in response to the tensile force within this displacement range. Therefore, upon release of the force, the elongation recovery rate becomes very high (i.e., excellent elasticity is exhibited). The method for determining the presence of a yield point will be described later.

[0030] The SS curve approximation formula for the biodegradable nonwoven fabric of this embodiment in the displacement range of 0 mm to 40 mm is preferably y = 0.13x to y = 1.38x, more preferably y = 0.13x to y = 0.63x, and even more preferably y = 0.13x to y = 0.38x. If a yield point is present in the displacement range of 0 mm to 40 mm at 30°C and the SS curve approximation formula for this range is y = 0.13x or greater, a nonwoven fabric with excellent stretchability is likely to be formed. The method for determining the SS curve approximation formula will be described later.

[0031] The biodegradable nonwoven fabric of this embodiment is composed of fibers containing a biodegradable thermoplastic resin. Examples of biodegradable thermoplastic resins include polyhydroxybutyrate valerate, polyhydroxybutyrate butyrate, nylon 4, polyglycolic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polybutylene terephthalate succinate, polybutylene succinate carbonate, polybutylene adipate terephthalate, polyethylene succinate, polyethylene terephthalate succinate, and polyvinyl alcohol. From the perspective of high biodegradability and / or stretchability, polyhydroxybutyrate valerate, polyhydroxybutyrate butyrate, and polybutylene adipate terephthalate are preferred. In addition, from the perspective of easy home compostability and soil compostability, polycaprolactone, nylon 4, polybutylene succinate adipate, and polybutylene adipate terephthalate are preferred. From the perspective of easy ocean compostability, polyhydroxybutyrate valerate, polycaprolactone, and nylon 4 are preferred. It should be noted that the details of home compostability, soil compostability, and ocean compostability will be described later. In addition, from the perspective of easy separation of some materials as the final product, polycaprolactone and polybutylene succinate adipate, which are meltable with heat similar to that of hot water, are preferred.

[0032] The biodegradable nonwoven fabric of this embodiment may have a laminated structure, for example, a laminated structure of SS, SMS, SMMS, SMSM, etc. Here, S refers to a spunbond long-fiber nonwoven fabric, and M refers to a meltblown ultrafine nonwoven fabric. Alternatively, a biodegradable nonwoven fabric may be used as a base material, with a short-fiber nonwoven fabric layer laminated thereto.

[0033] The shape of the fibers constituting the biodegradable nonwoven fabric of this embodiment is not particularly limited, and may have irregular cross-sections such as round, flat, C-shaped, Y-shaped, or V-shaped, preferably a round cross-section. Furthermore, the fibers may have an island-in-the-sea structure and / or a core-sheath structure or a split fiber structure.

[0034] The fibers constituting the biodegradable nonwoven fabric of the present embodiment may further contain one or more other resins, flame retardants, inorganic fillers, softeners, plasticizers, pigments, antistatic agents, and the like, depending on the intended purpose.

[0035] The fibers constituting the biodegradable nonwoven fabric of this embodiment may also contain a thermoplastic resin as a secondary component other than the aforementioned biodegradable thermoplastic resin (hereinafter also referred to as "secondary component resin"). When the total mass of the nonwoven fabric is set to 100 mass%, the content of the secondary component resin is preferably 0.5 mass% to 50 mass%, more preferably 2 mass% to 50 mass%, further preferably 5 mass% to 30 mass%, and most preferably 5 mass% to 25 mass%. If the addition amount is 0.5 mass% or more, the crystallinity of the nonwoven fabric can be controlled, thereby facilitating the control of the stretchability of the nonwoven fabric.

[0036] Examples of the resin as the secondary component include polyhydroxybutyrate valerate, polyhydroxybutyrate butyrate, nylon 4, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polybutylene terephthalate succinate, polybutylene succinate carbonate, polybutylene adipate terephthalate, polyethylene succinate, polyethylene terephthalate succinate, polyglycolic acid, polyvinyl alcohol, polypropylene, polyethylene terephthalate, and polyethylene. Polyhydroxybutyrate valerate, polyhydroxybutyrate butyrate, and polybutylene adipate terephthalate are preferred from the perspective of good biodegradability and / or stretchability. From the perspective of easy separation as a partial material of the final product, polycaprolactone and polybutylene succinate adipate, which are meltable with heat similar to hot water, are preferred. In addition, although the resin as the auxiliary component may contain non-biodegradable resins such as polypropylene, polyethylene terephthalate, and polyethylene, the content of the non-biodegradable resin is preferably less than 10% by mass from the perspective of satisfying various biodegradability requirements described below.

[0037] From the perspective of exhibiting antistatic properties and water absorption, the biodegradable nonwoven fabric of this embodiment may also contain a surfactant. The surfactant can be any of nonionic, anionic, or cationic types, and can include carboxylic acid, sulfonic acid, sulfate, phosphate, ester, ether, ester-ether, alkanolamide, alkylamine, and quaternary ammonium types. Ester types are preferred, and among the ester types, sorbitan fatty acid esters, polyglycerol fatty acid esters, and polyoxyalkylene alkyl esters are particularly preferred. These surfactants can be used alone or in combination.

[0038] From the perspective of exhibiting sufficient antistatic and water-absorbing properties, the surfactant adhesion rate is preferably 0.1 wt% or more, and more preferably 2.0 wt% or less relative to the mass of the nonwoven fabric. If the surfactant adhesion rate is 0.1 wt% or more and 2.0 wt% or less, sufficient performance can be obtained.

[0039] As the coating method of the surfactant, existing methods such as kiss coating, gravure coating, and spray coating can be used for coating, and can be appropriately selected according to the purpose. Specifically, when it is only necessary to show performance on one side, transfer methods such as kiss coating and / or gravure coating are preferred. When it is necessary to have the same performance on both sides, it is preferably coated using a spray coating method.

[0040] The biodegradable nonwoven fabric of this embodiment preferably has a weight per unit area of ​​10 g / m 2 Above and 450g / m 2 Below, more preferably 10g / m 2 ~250g / m 2 , more preferably 12g / m 2 ~70g / m 2 , most preferably 12g / m 2 ~40g / m 2 If the unit area weight is 10g / m 2 Above, the strength is sufficient, and if it is 450g / m 2 If the temperature is below 500°, sufficient stretchability can be maintained during normal heat treatment time such as calendering.

[0041] The shear viscosity of the biodegradable nonwoven fabric of this embodiment can be controlled by the molecular structure, molecular weight, viscosity of the resin, and / or the extrusion temperature, residence time, various water-containing additives, crystallinity and / or orientation of the nonwoven fabric during the production of the nonwoven fabric. For example, polybutylene terephthalate adipate and polybutylene succinate adipate are preferably used as the type of resin. It should be noted that when the nonwoven fabric is produced by the spunbond method, although the shear viscosity of the resulting nonwoven fabric is generally reduced by about 1% to 30% relative to the shear viscosity of the raw resin, the thermal decomposition properties of the resin, the water content of the resin, the thermal history until ejection, and / or the shear rate may vary.

[0042] The glass transition temperature of the biodegradable nonwoven fabric of this embodiment is preferably 25°C or lower, more preferably 10°C or lower, and even more preferably 0°C or lower. A glass transition temperature of 25°C or lower improves stretchability due to improved molecular chain mobility at room temperature. Furthermore, the SS curve obtained by stretching at 30°C is less likely to produce a yield point within the displacement range of 0 mm to 40 mm, further improving stretchability. Furthermore, even during the thermocompression bonding process, high molecular mobility reduces the risk of defects such as pinholes, even during embossing at high temperatures and high pressures, resulting in more elastic behavior. To achieve a glass transition temperature within the above range, the biodegradable nonwoven fabric of this embodiment preferably contains a biodegradable thermoplastic resin such as polyhydroxybutyrate valerate, polyhydroxybutyrate butyrate, polybutylene terephthalate adipate, polycaprolactone, or polybutylene succinate adipate.

[0043] The biodegradable nonwoven fabric of this embodiment combines biodegradability with excellent stretchability and is suitable for use in a wide range of fields, including medical / sanitary materials, industrial materials, vehicle interior / exterior materials, sound insulation and sound absorption materials, component transport trays, fruit and vegetable trays, food containers, seedling containers, agricultural materials such as mulch, lightweight packaging materials, and filters. It is particularly suitable for use as food filters such as coffee and / or tea bag filters, diapers, masks, agricultural materials, and lightweight packaging materials.

[0044] When the biodegradable nonwoven fabric of this embodiment is made of a biodegradable thermoplastic resin having a melting point of 100°C or less, the nonwoven fabric can be easily separated and recovered from products composed of multiple materials such as diapers by utilizing its property of melting and shrinking when exposed to hot water.

[0045] The biodegradable nonwoven fabric of this embodiment preferably has a high mobility component ratio of 4.5% or more and 7.9% or less, as measured by pulsed NMR at 30°C, more preferably 5.3% to 7.9%, and even more preferably 5.7% to 7.9%. If the high mobility component ratio is 4.5% or more, the proportion of amorphous mobility components at 30°C increases, resulting in more free, unconstrained molecular chains, making plastic deformation less likely to occur under tension. The method for determining the high mobility component ratio as measured by pulsed NMR at 30°C will be described later.

[0046] The 3% modulus index (N / 30mm / (g / m 2)) is greater than 0, preferably greater than 0.009, preferably less than 0.225, more preferably less than 0.212, even more preferably less than 0.096, and most preferably less than 0.080. A 3% modulus index of 0.225 or less facilitates maintaining sufficient flexural flexibility. The effect of a 3% modulus index greater than 0 and less than 0.212 is particularly pronounced when the glass transition temperature is 25°C or less.

[0047] When the biodegradable nonwoven fabric of the present embodiment has an embossed portion and a non-embossed portion, the thickness index (mm / (g / m) of the embossed portion) obtained by dividing the thickness of the embossed portion by the square root of the weight per unit area of ​​the biodegradable nonwoven fabric is 2 ) 0.5 ) is preferably 2.84 or more and 7.78 or less, more preferably 5.60 or less, and further preferably 4.04 or less. If the thickness index of the embossed portion is 2.84 or more, the embossed portion is not easily damaged, and pinholes caused by the process tension during the processing of the nonwoven fabric are not easily generated. If it is 7.78 or less, the crimping can fully play its role, and it is not easily damaged by forces in the tensile direction such as the process tension during the processing of the nonwoven fabric. In particular, when the glass transition temperature is 25°C or less, the effect of the thickness index of the embossed portion being 2.84 or more and 4.04 or less becomes higher. Generally speaking, when the thickness of the embossed portion is too thin, it will lead to a significant decrease in strength, but when the glass transition temperature is 25°C or less, a decrease in strength is not easily generated.

[0048] The polarized Raman spectroscopy of the fibers constituting the biodegradable nonwoven fabric of the present embodiment measures the Raman spectrum at 1612 cm-1 using polarized light parallel to the fiber axis. -1 The peak intensity I / / at 1612 cm-1 of the Raman spectrum measured with polarized light perpendicular to the fiber axis -1 The value of the ratio of the peak intensity I⊥ at I / / / I⊥ is preferably 3.2 or more and 7.9 or less, more preferably 4.9 to 7.9, and even more preferably 5.6 to 7.9. When I / / / I⊥ is 7.9 or less, excessive orientation can be prevented, and the thickness of the hot embossed part can be easily made thinner. When I / / / I⊥ is 3.2 or more, the molecules constituting the fiber are fully oriented, the stress relative to stretching is improved, and thus the stretchability is improved. The detailed measurement method of I / / / I⊥ will be described later.

[0049] The method for producing the biodegradable nonwoven fabric of this embodiment is not particularly limited, and known methods such as spunbonding, meltblowing, air-laid, carding, and papermaking can be employed. The biodegradable nonwoven fabric of this embodiment is preferably integrated by bonding. Examples of bonding methods include embossing, thermal bonding, columnar flow interlacing, mechanical interlacing, and needle punching. Long-fiber nonwoven fabrics are preferred due to their high production efficiency and the suppression of post-molding fuzzing. Furthermore, spunbonding is preferred.

[0050] In the spunbond process, the resin is heated and melted, then ejected from a spinning spinneret. The resulting spun yarn is cooled using a known cooling device and then drawn and thinned using a suction device such as an air suction pipe. The yarns discharged from the suction device are then unraveled and deposited on a conveyor belt to form a web. The web formed on the conveyor belt is then partially heat-bonded using a heated embossing roller or other partial heat-bonding device to produce a spunbond nonwoven fabric. Nonwoven fabrics produced using the spunbond process exhibit physical properties such as high fabric strength and the absence of short fibers that may fall out due to damage to the bonded areas. Furthermore, they are low-cost and highly productive.

[0051] In the spunbond method, a high-speed airflow traction device using an air jet is usually used, and the traction force can be adjusted by the amount of air introduced into the traction device. For the traction force, two silk fibers (fishing lines) with a diameter of 0.235 mm and the same length as the full length of the traction device (in this specification, nylon silk fibers "Silver Scale (No. 2 / Natural / 50m roll monomer) manufactured by Toray Industries, Ltd. are used.) are put into the traction device, and the stress is measured by a spring balance connected to the silk fibers, and then divided by the length of the silk fibers put in to calculate the traction force (mN / m). The traction force is preferably greater than 27mN / m and less than 125mN / m, more preferably 38mN / m to 93mN / m, and most preferably 70mN / m to 93mN / m. If the traction force is less than 125mN / m, the breakage of the yarn during spinning can be fully suppressed, and the excessive increase in birefringence Δn after hot pressing and / or fixed-length heat treatment can be suppressed by suppressing excessive oriented crystallization. When the pulling force is 27 mN / m or more, oriented crystallization can be appropriately promoted, thermocompression bonding can be enabled, and a nonwoven fabric having sufficient strength can be obtained.

[0052] The biodegradable nonwoven fabric of the present embodiment may have a three-layer structure of spunbond (S) / meltblown (M) / spunbond (S). The aforementioned resins can be used as the material constituting the meltblown layer.

[0053] The average fiber diameter of the meltblown layer is 0.3 μm to 7 μm, preferably 0.6 μm to 4 μm. A fiber diameter of 0.3 μm or greater allows for spinning under mild conditions using the meltblowing method, which tends to suppress fiber breakage during spinning. An average fiber diameter of 7 μm or less allows the meltblown layer to function as fine fibers, filling the gaps in the spunbond layer and tending to form a dense structure.

[0054] The meltblown layer preferably has a weight per unit area of ​​1.0 g / m 2 Above and 100.0g / m 2 Below, more preferably 1.0g / m 2 Above and 60.0g / m 2 Below, more preferably 1.2g / m 2 Above and 16.0g / m 2 Below, most preferably 1.5g / m 2 Above and 10.0g / m 2 The unit area weight of the meltblown layer is 1.0 g / m 2 When the above is achieved, sufficient repair performance can be obtained as a filter. The unit area weight of the meltblown layer is 100.0g / m 2 When the viscosity is less than 50%, the nonwoven fabric structure can be suppressed from becoming dense, and the pressure loss does not increase.

[0055] The method of thermocompression bonding in the production of the biodegradable nonwoven fabric of this embodiment is not limited. It can be performed using a combination of an embossing roll with a concave-convex pattern on its surface and a flat roll without concave-convex patterns, or using a pair of embossing rolls with both having concave-convex patterns on their surfaces. Furthermore, the material of the roll surface is also not limited and can be made of metal, rubber, resin, etc. When using an embossing roll with a concave-convex pattern on its surface, thermocompression bonding is performed at a roll temperature preferably at least 10°C lower than the melting point of the resin of the nonwoven fabric, a linear pressure preferably between 5 N / mm and 100 N / mm, more preferably between 20 N / mm and 80 N / mm, and a bonding area ratio preferably between 3% and 50%, more preferably between 6% and 40%. By performing thermocompression bonding within an appropriate range, both the stretchability of the nonwoven fabric and the bonding performance can be achieved. It should be noted that the "melting point of the resin of the nonwoven fabric" can be measured using a differential scanning calorimeter (DSC) as described below. When multiple melting peaks are present, the peak with the largest area is taken as the melting point.

[0056] In the manufacture of the biodegradable nonwoven fabric of the present embodiment, regardless of whether the aforementioned hot pressing step is included, a fixed-length heat treatment can be performed. Fixed-length heat treatment refers to heat treatment performed under a state in which the nonwoven fabric dimensions in the length and width directions are controlled to remain unchanged during the heat treatment. The nonwoven fabric obtained by hot pressing the nonwoven fabric web just after spinning and then performing a fixed-length heat treatment has good surface smoothness and excellent elongation in a hot environment. Therefore, it is not easy to be damaged during the molding process, and a molded body with an aesthetically pleasing shape can be easily obtained. As a method for performing fixed-length heat treatment, conventional methods can be adopted, and hot air drying, needle chain tenter drying, hot plate, calender processing, felt drum flatting processing, air permeability processing, hot pressing, etc. can also be adopted. As the temperature range for fixed-length heat setting, as long as it is a temperature at which the resin constituting the nonwoven fabric does not adhere to the device and the fibers of the nonwoven fabric are moderately bonded, it can be sufficient.

[0057] The biodegradable nonwoven fabric of this embodiment can improve its crystallinity and suppress its thermal shrinkage by aging under specific conditions. Specific aging conditions include storage at 40°C for 10 days or more, which can easily achieve the above-mentioned effects.

[0058] Example

[0059] Hereinafter, the present invention will be described in detail with reference to examples.

[0060] First, the measurement methods, evaluation methods, etc. used in Examples and Comparative Examples are described.

[0061] (1) The presence or absence of a yield point in the displacement range of 0 mm to 40 mm in the SS curve obtained by stretching the biodegradable nonwoven fabric at 30°C

[0062] Using a Shimadzu Autograph AG-X plus (load cell: 1 kN), a 30 mm wide specimen was stretched under the conditions of a strain origin of 0.1% FS, a grip length of 100 mm, and a tensile speed of 300 mm / min to generate an SS curve. This elongation test was repeated 10 times, and the SS curve with the breaking stress closest to the average value was selected. If the curve showed an upward convexity (the SS curve was above the straight line connecting the points of displacement 0 mm and 40 mm), it was determined to have a yield point.

[0063] (2) Approximate formula for the displacement range of 0 mm to 40 mm in the SS curve obtained by stretching the biodegradable nonwoven fabric at 30°C

[0064] For the SS curve selected in (1) above, a graph was plotted within the 40 mm displacement range using Microsoft Excel. For this graph, the approximate equation was obtained by linear function approximation using the "Add Approximate Curve" option in Excel.

[0065] (3) Weight per unit area (g / m 2 )

[0066] According to JIS L-1913, the total area should be 1500cm 2 The nonwoven fabric sample is cut into three pieces (20 cm wide x 25 cm long) and converted to the mass per unit area. It should be noted that the weight per unit area is generally measured using the above method, but if a sufficient sample size is not available, it can be measured using any size, such as a 5 cm square.

[0067] (4) Average fiber diameter (μm)

[0068] Using a VHX-700F microscope manufactured by KEYENCE, photographs were taken at a magnification of 500 times, and the average value of 10 fibers in focus in the observation field was used to determine the value.

[0069] (5) Glass transition temperature (℃)

[0070] Using a differential scanning calorimeter DSC6000 manufactured by PerkinElmer, approximately 5.0 mg of the nonwoven fabric was heated in a nitrogen atmosphere at a heating rate of 10°C / min from -50°C to a temperature near the melting point (Tm) + 60°C. The glass transition temperature (Tg) was determined as the starting temperature of the secondary transition of heat in the secondary transition region corresponding to the transition region from the glass state to the rubber state.

[0071] (6) Melting point of nonwoven resin (°C)

[0072] Using a PerkinElmer DSC6000 differential scanning calorimeter, approximately 5.0 mg of the nonwoven fabric was heated from -50°C to 350°C in a nitrogen atmosphere at a heating rate of 10°C / min. The endothermic peak detected was defined as the melting peak, and the peak apex was defined as the melting point. It should be noted that multiple melting peaks may be observed depending on the type and / or amount of resin constituting the nonwoven fabric.

[0073] (7) 3% modulus index in the machine direction ((N / 30mm) / (g / m 2 ))

[0074] Using an Autograph AG-X plus (load cell: 1 kN) manufactured by Shimadzu Corporation, a 30 mm wide specimen was stretched under the conditions of a strain origin of 0.1% FS, a clamp length of 100 mm, and a tensile speed of 300 mm / min. The tensile strength per 30 mm width obtained at an extension of 3 mm was defined as the 3% modulus. Ten measurements were performed in the machine (length) direction of the nonwoven fabric, and the average value was determined. The value obtained by dividing this average by the weight per unit area was used as the 3% modulus index in the machine direction.

[0075] (8) Ratio of high-mobility components measured by pulsed NMR at 30°C (V, %)

[0076] The ratio (V, %) of the high mobility component obtained by pulse NMR can be calculated according to the following method. As a measuring device for pulse NMR, Minispec MQ20 ​​manufactured by BRUKER was used, 1H was used as the measuring nucleus, the solid echo method was used as the measuring method, and the cumulative number of times was set to 256 times for measurement. Specifically, a glass tube with an outer diameter of 10 mm in which a measuring sample cut to a height of 1.0 cm was placed was placed in a device controlled at a temperature of 30°C, and the T2 relaxation time of 1H was measured by the solid echo method 5 minutes after the setting. During the measurement, the repetition waiting time during the measurement was set to more than 5 times the T1 relaxation time of the sample. According to the magnetization decay curve obtained as above (a curve indicating the change of magnetization intensity over time), when the signal intensity at the start of the measurement at the start of signal acquisition is set to 100%, the signal intensity at 0.4 msec is used as the ratio (V, %) of the high mobility component in this embodiment.

[0077] (9) 1612 cm of the Raman spectrum measured with polarized light parallel to the fiber axis -1 The peak intensity at 1612 cm-1 (I / / ) is relative to the peak at 1612 cm-1 of the Raman spectrum measured with polarized light perpendicular to the fiber axis. -1 The value of the ratio of the peak intensity (I⊥) at (I / / / I⊥)

[0078] Using a Raman spectrophotometer InViaReflex manufactured by Renishaw Co., Ltd., the polarization Raman spectrum of 1612 cm-1 was measured for any one fiber of the fiber layer (I) in the sample while the sample was set in a state where the polarization plane of the excitation light was parallel to the fiber axis. -1 Next, the sample was rotated 90° and the polarization Raman spectrum at 1612 cm was measured with the polarization plane of the excitation light perpendicular to the fiber axis. -1The peak intensity at (I⊥) is calculated using the average value of 10 fibers to determine the ratio of (I / / ) to (I⊥) (I / / / I⊥). A larger value of (I / / / I⊥) indicates a higher orientation of the molecular chains relative to the fiber axis. The polarized Raman spectrum was measured with the optical axis of the polarizer on the detection side parallel to the optical axis of the excitation light.

[0079] In addition, the measurement conditions using a Raman spectrophotometer are as follows.

[0080] (Measurement conditions)

[0081] Laser wavelength: 532nm

[0082] Excitation light intensity at the measurement position: 1.5mW

[0083] Objective lens: 20x (NA0.40)

[0084] Diffraction grating: 1800gr / mm

[0085] Exposure time: 2 seconds

[0086] Accumulated times: 4 times

[0087] (10) Thickness index of embossed part (mm / (g / m 2 ) 0.5 )

[0088] The nonwoven fabric sample was frozen and cut along the cross-sectional direction, and the thickness of the embossed portion was observed using a scanning electron microscope VE-8800 manufactured by KEYENCE. The magnification was set to ×200, and the thickness of the embossed portion was measured at a total of 5 locations: the center of the embossed portion, a position 20 μm on both sides of the center, and a position 20 μm outside. The values ​​of 3 locations after removing the maximum and minimum values ​​from the 5 locations were used as the data for each embossing, and the average value of the thickness of the 5 embossed locations, that is, a total of 15 locations, was used as the thickness (mm) of the embossed portion. Furthermore, the value obtained by dividing this value by the square root of the weight per unit area of ​​the nonwoven fabric was used as the thickness index.

[0089] (11) Biodegradability

[0090] The following four biodegradation tests are carried out. If at least one test passes, it is judged to be biodegradable.

[0091] Industrial compostability

[0092] In accordance with ISO 14855-1 (58±2°C) and JIS K 6953-1, under conditions simulating industrial composting (composting plant), the organic components of municipal solid waste were composted at 58±2°C. The biodegradation rate was calculated as the ratio of the amount of carbon dioxide produced to the theoretical amount of carbon dioxide produced. If the biodegradation rate reached 90% or more within 6 months, the product was judged as "pass" (0); if it failed, it was judged as "×".

[0093] <Home compostability>

[0094] In accordance with ISO 14855-1 (28±2°C) and JIS K 6953-1, a biodegradation test is conducted at 28±2°C. The biodegradation rate is calculated as the ratio of the amount of carbon dioxide produced to the theoretical amount of carbon dioxide produced. If the biodegradation rate reaches 90% or more within 6 months, it is judged as "pass" and "failed".

[0095] <Soil compostability>

[0096] In accordance with ISO 17556 (25±2°C), a biodegradation test is conducted at 25±2°C. The biodegradation rate is calculated as the ratio of the amount of carbon dioxide produced to the theoretical amount of carbon dioxide produced. If the biodegradation rate reaches 90% or more within 6 months, it is judged as "pass" and "failed".

[0097] Ocean compostability

[0098] Biodegradation tests were conducted at 30±1°C according to ASTM D6691 (30±1°C). The biodegradation rate was determined as the ratio of the amount of carbon dioxide produced to the theoretically produced carbon dioxide. If the biodegradation rate reached 90% or more within 6 months, it was judged as "pass" (0), and "failed" (×).

[0099] (12) Stretchability of nonwoven fabrics (elongation recovery) (%)

[0100] Using a Shimadzu Autograph AG-X plus (load cell: 1 kN), a 30 mm wide specimen was stretched to a desired displacement of A% at a strain origin of 0.1% FS, a grip length of 100 mm, and a stretching rate of 300 mm / min. Before stretching, a line was drawn at the 100 mm grip length. After stretching, the dimensions were re-measured using a vernier caliper. The dimensional change before and after stretching was designated B mm, and the following formula was used:

[0101] Shrinkage after elongation (%) = B / (100+100A-100)

[0102] The shrinkage after elongation is measured. The closer the shrinkage after elongation is to 100%, the closer it is to the length of the sample before stretching, and therefore the higher the stretchability is.

[0103] [Example 1]

[0104] A single-screw extruder was used to melt and mix polybutylene adipate terephthalate (abbreviated as PBAT in the table). The spunbond method was used to extrude the filaments at a discharge rate of 0.9 g / min·Hole and a spinning temperature of 210°C. The filaments were then pulled with a traction force of 93 mN / m by a high-speed airflow traction device using an air jet, and deposited on a moving collecting surface to prepare a biodegradable long fiber web (circular cross-section).

[0105] Next, a pair of embossing rollers, consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface, were used to perform heat pressing under the conditions of a pressing area ratio of 11%, a temperature of 105°C for both rollers, and a roller linear pressure of 30 N / mm, to obtain a unit area weight of 20 g / m 2 Biodegradable nonwoven fabrics.

[0106] [Examples 2 to 7]

[0107] A biodegradable nonwoven fabric was produced in the same manner as in Example 1 except that the line speed was changed so as to achieve the weight per unit area shown in the following table.

[0108] [Example 8]

[0109] A biodegradable nonwoven fabric was produced in the same manner as in Example 1 except that the embossing temperature was changed.

[0110] [Example 9]

[0111] A single screw extruder was used to melt and mix polybutylene succinate adipate (PBSA in the table). The filament group was extruded toward the moving collection surface by a spunbond method with a discharge rate of 0.9 g / min·Hole, a spinning temperature of 140°C, and a pulling force of 93 mN / m to prepare a biodegradable long fiber mesh (circular cross-section). Next, a pair of embossing rollers consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface were used. The hot pressing was performed under the conditions of a pressing area rate of 11%, a temperature of 75°C for both rollers, and a roller line pressure of 30 N / mm to obtain a unit area weight of 20 g / m 2 Biodegradable nonwoven fabrics.

[0112] [Example 10]

[0113] A single-screw extruder was used to melt and mix polybutylene succinate (PBS in the table). The filament group was extruded toward the moving collection surface by the spunbond method at a discharge rate of 0.9 g / min·Hole, a spinning temperature of 210°C, and a pulling force of 93 mN / m to prepare a biodegradable long fiber mesh (circular cross-section). Next, a pair of embossing rollers consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface were used. The hot pressing was performed under the conditions of a pressing area rate of 11%, a temperature of 100°C for both rollers, and a roller line pressure of 30 N / mm to obtain a unit area weight of 20 g / m 2 Biodegradable nonwoven fabrics.

[0114] [Examples 11 and 12]

[0115] A biodegradable nonwoven fabric was produced in the same manner as in Example 1 except that polybutylene succinate and polycaprolactone were added as auxiliary components.

[0116] [Example 13]

[0117] A biodegradable nonwoven fabric was produced in the same manner as in Example 1 except that the pulling force was changed.

[0118] [Example 14]

[0119] As the short fibers, raw cotton of polybutylene adipate terephthalate with a single fiber diameter of 30 μm was used, and the raw cotton was carded to a weight of 20 g / m 2 The nonwoven fabric mesh was then placed on a 100-mesh wire mesh and treated with a high-pressure liquid flow treatment device equipped with a 0.08mm aperture spray hole with a pore size of 0.7mm to integrate the mesh. The liquid flow spraying condition was set to 60kg / cm 2 1 time under water pressure of 120kg / cm 2 1 time under water pressure of 1. In addition, from the opposite side at 120kg / cm 2 Afterwards, in order to remove excess moisture from the obtained web, a hot air dryer was used to dry it at 70° C. to obtain a biodegradable nonwoven fabric.

[0120] [Example 15]

[0121] The biodegradable nonwoven fabric obtained in Example 14 was heat-pressed using a pair of embossing rollers, one of which had a concave-convex pattern on its surface, at a pressure area ratio of 14%, a temperature of 105°C for both the upper and lower rollers, and a roller linear pressure of 30 N / mm to obtain a weight per unit area of ​​20 g / m 2 Biodegradable nonwoven fabrics.

[0122] [Example 16]

[0123] The biodegradable nonwoven fabric obtained in Example 14 was needle punched at a density of 400 needles / cm 2 The fiber mesh is interwoven by needle punching to obtain a unit area weight of 20g / m 2 Biodegradable nonwoven fabrics.

[0124] [Comparative Example 1]

[0125] A single-screw extruder was used to melt and mix polylactic acid (abbreviated as PLA in the table). The filament group was extruded toward the moving collection surface by a spunbond method with a discharge rate of 0.9 g / min·Hole, a spinning temperature of 230°C, and a pulling force of 93 mN / m to prepare a biodegradable long fiber mesh (circular cross-section). Next, a pair of embossing rollers consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface were used. The hot pressing was performed under the conditions of a pressing area rate of 11%, a temperature of 130°C for both rollers, and a roller line pressure of 20 N / mm, to obtain a unit area weight of 20 g / m 2 nonwoven fabrics.

[0126] [Comparative Example 2]

[0127] A single screw extruder was used to melt and mix polyethylene terephthalate (referred to as PET in the table). The filament group was extruded toward the moving collection surface by the spunbond method at a discharge rate of 0.9 g / min·Hole, a spinning temperature of 290°C, and a pulling force of 93 mN / m to prepare a biodegradable long fiber mesh (circular cross-section). Next, a pair of embossing rollers consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface were used. The hot pressing was performed under the conditions of a pressing area rate of 11%, a temperature of 220°C for both rollers, and a roller line pressure of 20 N / mm, to obtain a unit area weight of 20 g / m 2 nonwoven fabrics.

[0128] [Comparative Example 3]

[0129] A single screw extruder was used to melt and mix polypropylene (abbreviated as PP in the table). The filament group was extruded toward the moving collection surface by the spunbond method at a discharge rate of 0.9 g / min·Hole, a spinning temperature of 230°C, and a pulling force of 93 mN / m to prepare a biodegradable long fiber mesh (circular cross-section). Next, a pair of embossing rollers consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface were used. The hot pressing was performed under the conditions of a pressing area rate of 11%, a temperature of 140°C for both rollers, and a roller line pressure of 20 N / mm, to obtain a unit area weight of 20 g / m 2 nonwoven fabrics.

[0130] [Comparative Example 4]

[0131] A single screw extruder was used to melt and mix polycaprolactone (abbreviated as PCL in the table). The filament group was extruded toward the moving collection surface by the spunbond method at a discharge rate of 0.9 g / min·Hole, a spinning temperature of 110°C, and a pulling force of 93 mN / m to prepare a biodegradable long fiber mesh (circular cross section). Next, a pair of embossing rollers consisting of a roller with a concave-convex pattern on the surface and a roller with a smooth surface were used. The hot pressing was performed under the conditions of a pressing area rate of 11%, a temperature of 50°C for both rollers, and a roller line pressure of 30 N / mm to obtain a unit area weight of 20 g / m 2 Biodegradable nonwoven fabrics.

[0132] [Comparative Example 5]

[0133] A biodegradable nonwoven fabric was produced in the same manner as in Example 1 except that the embossing temperature was changed.

[0134] [Comparative Example 6]

[0135] A biodegradable nonwoven fabric was produced in the same manner as in Example 1 except that the pulling force was changed.

[0136] [Example 17]

[0137] In addition to the unit area weight of 5.0g / m 2 A mesh (weight per unit area 5.0 g / m2) was prepared in the same manner as in Example 1 except that the line speed was adjusted in the same manner as in Example 1. 2 ) on the melt-blown nozzle, with a spinning temperature of 210 ° C, heated air 230 ° C, 1000Nm 3 / hr conditions directly sprayed to form a melt-blown mesh (weight per unit area 2.0g / m 2 , average fiber diameter 2.1 μm). At this time, the distance from the meltblown nozzle to the spunbond mesh was set to 110 mm, and the suction wind speed of the collecting surface directly below the meltblown nozzle was set to 7 m / sec. Then, a spunbond mesh of polylactic acid similar to the aforementioned spunbond mesh was formed on the obtained meltblown mesh. The obtained laminated mesh was heat-pressed in the same manner as in Example 1 to obtain a total unit area weight of 12.0 g / m 2 nonwoven fabrics.

[0138] [Example 18]

[0139] A biodegradable nonwoven fabric was produced in the same manner as in Example 18 except that the cross-sectional shape of the monofilament in the first spunbond layer was changed to a core-sheath ratio of 50 / 50 wt%, PBAT was used on the core side, and PBSA was used on the sheath side.

[0140] The physical properties and evaluation results of the nonwoven fabrics of Examples 1 to 18 and Comparative Examples 1 to 6 are shown in Tables 1 to 4 below. In the tables, in the SS curves obtained by stretching the biodegradable nonwoven fabric at 70°C, the case where the SS curve approximation formula for the displacement range of 0 to 40 mm is y = 0.13x to y = 1.38x is designated as "Condition A," the case where it is y = 0.13x to y = 0.63x is designated as "Condition B," and the case where it is y = 0.13x to y = 0.38x is designated as "Condition C."

[0141] [Table 1]

[0142]

[0143] [Table 2]

[0144]

[0145] [Table 3]

[0146]

[0147] [Table 4]

[0148]

Table 4

[0149]

[0150] Industrial applicability

[0151] The biodegradable nonwoven fabric of the present invention combines biodegradability with excellent stretchability and is therefore suitable for use in a wide range of fields, including medical / sanitary materials, industrial materials, vehicle interior / exterior materials, sound insulation materials, sound absorption materials, agricultural materials such as seedling containers and / or mulch films, lightweight packaging materials, and filters.

Claims

1. A biodegradable nonwoven fabric, characterized in that The fiber is composed of a fiber containing a biodegradable thermoplastic resin, and the SS curve obtained by stretching the fiber in an atmosphere at 30° C. has no yield point in the displacement range of 0 mm to 40 mm.

2. The biodegradable nonwoven fabric according to claim 1, wherein The 3% modulus index in the mechanical direction obtained by tensile test (N / 30mm / (g / m 2 )) is greater than 0 and less than 0.

225.

3. The biodegradable nonwoven fabric according to claim 2, wherein 3% modulus index in the machine direction (N / 30mm / (g / m 2 )) is less than 0.

096.

4. The biodegradable nonwoven fabric according to any one of claims 1 to 3, wherein The ratio of the high motility component determined by pulse NMR measurement at 30° C. was 4.5 to 7.9%.

5. The biodegradable nonwoven fabric according to any one of claims 1 to 3, wherein Polarized Raman spectroscopy of the fiber was used to measure the Raman spectrum with polarized light parallel to the fiber axis at 1612 cm -1 The peak intensity I / / at 1612 cm-1 of the Raman spectrum measured with polarized light perpendicular to the fiber axis -1 The value of the ratio of the peak intensities I⊥ at I / / / I⊥ is 3.2 to 7.

9.

6. The biodegradable nonwoven fabric according to any one of claims 1 to 3, wherein The glass transition temperature of the biodegradable thermoplastic resin is 25° C. or lower.

7. The biodegradable nonwoven fabric according to any one of claims 1 to 3, wherein The biodegradable thermoplastic resin is at least one selected from the group consisting of polybutylene succinate adipate, polybutylene adipate terephthalate, polyhydroxybutyrate valerate, and polyhydroxybutyrate butyrate.

8. The biodegradable nonwoven fabric according to claim 7, wherein The biodegradable thermoplastic resin is polybutylene adipate terephthalate.

9. The biodegradable nonwoven fabric according to any one of claims 1 to 8, characterized in that The biodegradable nonwoven fabric contains at least one layer of spunbonded long fiber nonwoven fabric.

10. The biodegradable nonwoven fabric according to claim 9, characterized in that The biodegradable nonwoven fabric has a three-layer structure of spunbond long fiber nonwoven fabric / meltblown ultrafine fiber nonwoven fabric / spunbond long fiber nonwoven fabric.

11. A diaper comprising the biodegradable nonwoven fabric according to any one of claims 1 to 3. 12 . A wiping cloth comprising the biodegradable nonwoven fabric according to claim 1 .

13. A heating pad comprising the biodegradable nonwoven fabric according to any one of claims 1 to 3.

14. A lightweight packaging material comprising the biodegradable nonwoven fabric according to any one of claims 1 to 3.

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