Biodegradable nonwoven fabric and method for manufacturing molded body

Abstract

A method for manufacturing a biodegradable nonwoven fabric and a molded body is provided, which exhibit excellent biodegradability, uniform formability, and shapeability (resulting in a molded body with less breakage / fuzzing / stretching unevenness and a neat shape in a shorter time), and also provides good dimensional stability after molding. The biodegradable nonwoven fabric of the present invention is characterized by being a nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin, with a basis weight of 10 g / m². 2 Above and 450g / m 2 The difference between the melting point and the crystallization initiation temperature of the nonwoven fabric is above 91°C, and the enthalpy of cold crystallization ΔH of the nonwoven fabric is above 1.0 J / g.

Description

Technical Field

[0001] This invention relates to biodegradable nonwoven fabrics. Background Technology

[0002] Previously, it was known that thermoforming of biodegradable nonwoven fabrics resulted in molded products that were used in various fields and had a wide range of applications. However, in the thermoforming of biodegradable nonwoven fabrics, it is difficult to obtain molded products that are free from cracks, have minimal stretching unevenness, and are neatly shaped according to the mold, thus making it difficult to achieve good dimensional stability as molded products.

[0003] Biodegradable molding nonwovens made of polylactic acid or polybutylene succinate are disclosed in the following references 1 and 2.

[0004] Furthermore, Patent Document 3 discloses a biodegradable long-fiber nonwoven fabric formed from a polylactic acid polymer and an aliphatic polyester copolymer. Patent Document 3 uses an island-type composite long fiber comprising a polylactic acid polymer forming a sea portion and an aliphatic polyester copolymer forming an island portion, with the aliphatic polyester copolymer forming the island portion exposed on the fiber surface, thereby obtaining a nonwoven fabric with improved thermal adhesion and shapeability.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 9-95848

[0008] Patent Document 2: Japanese Patent Application Publication No. 2000-136478

[0009] Patent Document 3: International Publication No. 2018 / 070490 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] However, the biodegradable nonwoven fabrics for molding described in Patent Documents 1 and 2 are formed by partially heat-pressing the constituent fibers together, resulting in excessively strong adhesion between the fibers, making it difficult to thermoform without breaking the bag. In addition, it is difficult to obtain a molded body with a deep initial molding depth.

[0012] In addition, the nonwoven fabric described in Patent Document 3 can produce a molded body with no cracks, less uneven stretching, and a neat shape that conforms to the shape of the molding die in a shorter time during thermoforming. However, in certain applications, higher dimensional stability of the molded body is required.

[0013] In view of the problems of the prior art, the object of the present invention is to provide a biodegradable nonwoven fabric and a method for manufacturing the molded article, which are biodegradable, have excellent uniformity and formability (to obtain a molded article with less breakage / fuzzing / stretching unevenness and a neat shape in a shorter time), and have good dimensional stability after molding.

[0014] Solution for solving the problem

[0015] To solve the aforementioned problems, the inventors conducted in-depth research and repeated experiments. Focusing on the characteristics of the nonwoven fabric before molding, they discovered that the nonwoven fabric, composed of fibers containing biodegradable thermoplastic resin, has a unit area weight of 10 g / m². 2 Above and 450g / m 2 Within the following range, the difference between the melting point and the crystallization initiation temperature of the nonwoven fabric is set to 91°C or higher, and the enthalpy of cold crystallization ΔH of the nonwoven fabric is set to 1.0 J / g or higher. This results in excellent uniformity and formability, and consequently, good dimensional stability after molding, thus completing the present invention.

[0016] That is, the present invention is as described below.

[0017] [1] A biodegradable nonwoven fabric, characterized in that it is a nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin, with a unit area weight of 10 g / m². 2 Above and 450g / m 2 The difference between the melting point and the crystallization initiation temperature of the nonwoven fabric is above 91°C, and the enthalpy of cold crystallization ΔH of the nonwoven fabric is above 1.0 J / g.

[0018] [2] The biodegradable nonwoven fabric described in [1] above, wherein the difference between the melting point and the crystallization initiation temperature of the aforementioned nonwoven fabric is below 159°C.

[0019] [3] The biodegradable nonwoven fabric described in [1] or [2] above, wherein the aforementioned enthalpy of cold crystallization ΔH is below 20.0 J / g.

[0020] [4] The biodegradable nonwoven fabric according to any one of [1] to [3] above, wherein the aforementioned fiber containing biodegradable thermoplastic resin contains more than 70% by weight and less than 99.5% by weight of the biodegradable thermoplastic resin as a main component, and contains more than 0.5% by weight and less than 30% by weight of a thermoplastic resin different from the main component as a secondary component.

[0021] [5] The biodegradable nonwoven fabric according to the above [4], wherein the aforementioned by-component is any one of the homopolymers or copolymers of one or more monomers selected from the group consisting of (meth)acrylic acid monomers, olefins, caprolactones, hydroxyalkanoates, alkylene glycols, dicarboxylic acids and diols.

[0022] [6] The biodegradable nonwoven fabric described in [5] above, wherein the aforementioned by-component is an aliphatic ester or an aromatic ester.

[0023] [7] The biodegradable nonwoven fabric according to [6] above, wherein the aforementioned by-component contains any one of polybutylene succinate, polybutylene adipate or polybutylene adipate.

[0024] [8] The biodegradable nonwoven fabric according to any one of [4] to [7] above, wherein the aforementioned fiber containing biodegradable thermoplastic resin is an island fiber in which the aforementioned main component forms a sea and the aforementioned secondary component forms an island.

[0025] [9] The biodegradable nonwoven fabric according to any one of [1] to [8] above, wherein the crimping area ratio of the aforementioned nonwoven fabric is 8% or more.

[0026]

[10] The biodegradable nonwoven fabric according to any one of [1] to [9] above, wherein the dimensional change rate in the MD direction at 80°C to 140°C obtained by thermomechanical analysis is less than -4.0%.

[0027]

[11] The biodegradable nonwoven fabric according to any one of [1] to

[10] above is a spunbond nonwoven fabric.

[0028]

[12] A method for manufacturing a molded body, comprising a step of thermoforming the biodegradable nonwoven fabric described in any one of [1] to

[11] above.

[0029]

[13] According to the manufacturing method described above

[12] , the deformation speed in the aforementioned thermoforming is 32 mm / s or more and 320 mm / s or less.

[0030]

[14] According to the manufacturing method described above

[12] , the deformation speed in the aforementioned thermoforming is 105 mm / s or more and 140 mm / s or less.

[0031]

[15] According to the manufacturing method described in

[12] or

[14] above, wherein the aforementioned nonwoven fabric is a spunbond nonwoven fabric in which the difference between the melting point and the crystallization initiation temperature of the aforementioned nonwoven fabric is less than 159°C, the aforementioned enthalpy of cold crystallization ΔH is less than 20.0 J / g, and the dimensional change rate in the MD direction at 80°C to 140°C obtained by the aforementioned thermomechanical analysis is less than -4.0%.

[0032] The effects of the invention

[0033] The biodegradable nonwoven fabric of the present invention is biodegradable and has excellent uniformity and formability (to obtain molded articles with less breakage / fuzzing / stretching unevenness and neat shape in a shorter time), and thus the dimensional stability of the molded articles is extremely good. Detailed Implementation

[0034] The embodiments of the present invention will be described in detail below.

[0035] The biodegradable nonwoven fabric of this embodiment is characterized in that it is a nonwoven fabric composed of fibers containing a biodegradable thermoplastic resin, with a unit area weight of 10 g / m². 2 Above and 450g / m 2 The difference between the melting point and the crystallization initiation temperature of the nonwoven fabric is above 91°C, and the enthalpy of cold crystallization ΔH of the nonwoven fabric is above 1.0 J / g.

[0036] The biodegradable nonwoven fabric of this embodiment is composed of fibers containing a biodegradable thermoplastic resin (hereinafter also referred to as "the resin of the main component"). Examples of biodegradable thermoplastic resins include polylactic acid (PLA) polymers, polyhydroxyalkanoates, polyhydroxybutyrate valerate, polyhydroxybutyrate hexanoate, nylon 4, polycaprolactone, polybutylene succinate (PBS), polybutylene adipate, polybutylene terephthalate succinate, polybutylene carbonate succinate, polybutylene adipate terephthalate, polyethylene succinate, polyethylene terephthalate succinate, polyglycolic acid, and polyvinyl alcohol. From the viewpoint of spinnability and processability, polylactic acid polymers are preferred.

[0037] Polylactic acid (PLA) polymers include polymers selected from the group consisting of D-lactic acid polymers, L-lactic acid polymers, copolymers of D-lactic acid and L-lactic acid, copolymers of D-lactic acid and hydroxycarboxylic acid, copolymers of L-lactic acid and hydroxycarboxylic acid, and copolymers of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or mixtures of two or more of these polymers. The D / L ratio of the PLA polymer can be set within a range that does not hinder spinnability or nonwoven fabric properties. The D-body ratio in the total weight of PLA is preferably 0 to 15%, more preferably 0.1 to 10%, and even more preferably 0.1 to 6%. If the D-body ratio is within these ranges, spinnability is good, and nonwoven fabrics can be stably obtained. Furthermore, the melting point, crystallinity, etc., are within appropriate ranges, making it easy to obtain nonwoven fabrics with the desired properties.

[0038] The melt flow rate (MFR) of polylactic acid polymers is preferably 20–120 g / 10 min at 210 °C, more preferably 30–70 g / 10 min. If the MFR at 210 °C is 20 g / 10 min or higher, the melt viscosity is appropriate, making it easy to refine fibers during the spinning process, thus resulting in good spinnability. On the other hand, if the MFR at 210 °C is 120 g / 10 min or lower, the melt viscosity is appropriate, thus reducing the occurrence of monofilament breakage during the spinning process, and improving spinnability.

[0039] The manufacturing method of the biodegradable nonwoven fabric in this embodiment is not limited, and known methods such as spunbonding, meltblowing, air-laid fabrication, carding, and papermaking can be used. The biodegradable nonwoven fabric of this embodiment is preferably integrated by bonding. As bonding methods, embossing, thermal bonding, columnar flow weaving, mechanical weaving, and needle punching can be used. From the viewpoint of efficient production and suppression of post-forming fuzzing, long-fiber nonwoven fabrics are preferred, and spunbonding is even more preferred.

[0040] In the spunbond process, resin is heated and melted, then extruded from a spinning spinneret. The resulting spun filaments are cooled using a known cooling device and then drawn and refined using a suction device such as an air suction pipe. The filaments discharged from the suction device are then split and piled onto a conveyor belt to form a web. Next, the web formed on the conveyor belt is partially heat-bonded using a partially heat-bonding device such as a heated embossing roller, thereby obtaining a spunbond nonwoven fabric. Nonwoven fabrics obtained using the spunbond method possess characteristics such as high fabric strength and no short fiber shedding due to breakage of the bonded portion, and are also low in cost and have high productivity.

[0041] The biodegradable nonwoven fabric of this embodiment can be laminated with other nonwoven fabrics, such as a layer within a multilayer laminated nonwoven fabric like SS, SMS, SMMS, or SMSM. Here, S refers to spunbond long-fiber nonwoven fabric, and M refers to meltblown ultrafine nonwoven fabric. Alternatively, a biodegradable nonwoven fabric can be used as a substrate, with short-fiber nonwoven fabric layers laminated on top.

[0042] The shape of the fibers constituting the biodegradable nonwoven fabric of this embodiment is not particularly limited. Different cross-sections such as round, flat, C-shaped, Y-shaped, and V-shaped are used, with round cross-sections being preferred. Furthermore, island-shaped, core-sheath, and split fiber structures are also possible.

[0043] The fibers constituting the biodegradable nonwoven fabric of this embodiment may, as needed, contain one or more of the following: other resins, copolymers other than aliphatic polyester copolymers, flame retardants, inorganic fillers, softeners, plasticizers, pigments, antistatic agents, etc.

[0044] The biodegradable nonwoven fabric in this embodiment has a unit area weight of 10 g / m². 2 Above and 450g / m 2 The following is preferred: 20-400g / m 2 More preferably 20-250 g / m 2 If the weight per unit area is 10g / m² 2 The above results in sufficient strength; on the other hand, if it is 450g / m²... 2 The following process ensures sufficient heat transfer to the nonwoven fabric during molding, making it easy to obtain molded bodies with high dimensional stability.

[0045] For the biodegradable nonwoven fabric of this embodiment, the difference between the melting point of the nonwoven fabric and its crystallization initiation temperature is 91°C or more. Preferably, the difference between the melting point and the crystallization initiation temperature of the nonwoven fabric is 95°C or more, more preferably 103°C or more, and even more preferably 160°C or less. If this temperature difference is less than 91°C, even if the molding process temperature is increased, crystallization will not be sufficient, and a molded body with high dimensional stability cannot be obtained.

[0046] The enthalpy of crystallization ΔH of the biodegradable nonwoven fabric in this embodiment is 1.0 J / g or more, preferably 1.2 J / g or more, more preferably 3.3 J / g or more, and even more preferably 8.6 J / g. If the enthalpy of crystallization ΔH is 1.0 J / g or more, sufficient crystallization can be achieved during the molding process, easily resulting in a molded body with high dimensional stability. Furthermore, from the viewpoint of obtaining a molded body with high dimensional stability by reducing the amorphous portion after molding, the enthalpy of crystallization is preferably 20.0 J / g or less, more preferably 17.5 J / g or less, and even more preferably 15.0 J / g or less.

[0047] Specific methods for achieving a melting point and crystallization initiation temperature difference of 91°C or higher for the aforementioned nonwoven fabric include, for example, adjusting the type of biodegradable thermoplastic resin, the mixing of secondary thermoplastic resins (type of secondary thermoplastic resins, mixing ratio with the main resin, etc.), spinning conditions (resin temperature, ejection rate, filament traction, cooling, etc.), hot pressing conditions (roller temperature, pressure, speed, embossing pattern, etc.), fixed-length heat setting conditions, and curing conditions (storage conditions, etc.). These conditions will be explained in detail below. It should be noted that the same method applies to achieving an enthalpy of ΔH at the cold crystallization peak of the aforementioned nonwoven fabric of 1.0 J / g or higher.

[0048] For the biodegradable nonwoven fabric of this embodiment, the dimensional change rate in the MD direction at 80°C to 140°C, obtained by thermomechanical analysis, is preferably less than -4.0%, more preferably less than -4.5%, and even more preferably less than -5.0%. A small dimensional change rate in the nonwoven fabric, meaning it is easy to shrink, implies sufficient amorphous portions. If the aforementioned dimensional change rate is less than -4.0%, crystallization is promoted by heat and stretching during thermoforming, thereby improving formability and dimensional stability of the molded article.

[0049] [Mixing of thermoplastic resins as secondary components]

[0050] The fibers constituting the biodegradable nonwoven fabric of this embodiment may contain, in addition to the aforementioned biodegradable thermoplastic resin, a secondary thermoplastic resin (hereinafter also referred to as "secondary component resin"). When the total amount of resin is set to 100% by weight, the content of the aforementioned secondary component resin is preferably more than 0% by weight and less than 30% by weight, more preferably 0.5% to 30% by weight, further preferably 3% to 27% by weight, and most preferably 5% to 25% by weight. If the addition amount is 0.5% by weight or more, the crystallization initiation temperature of the nonwoven fabric can be lowered, and crystallization can be promoted at a lower temperature during molding. On the other hand, if the addition amount is 30% by weight or less, crystallization is not inhibited, and sufficient crystallization occurs during molding.

[0051] Resins used as by-products can include aliphatic esters, aromatic esters, or homopolymers or copolymers of one or more monomers selected from the group consisting of (meth)acrylic acid monomers, olefins, caprolactones, hydroxyalkanoates, alkylene glycols, diacids, and glycols. Furthermore, resins used as by-products can be a mixture of various biodegradable polymers. From the viewpoint of compatibility with biodegradable thermoplastic resins and spinnability, aliphatic esters and aromatic esters are preferred; more specifically, polybutylene succinate, polybutylene adipate terephthalate, and polybutylene adipate succinate are preferred.

[0052] The melt flow rate (MFR) of the secondary component resin is preferably 100 g / 10 min or less, more preferably 20 to 80 g / 10 min, and even more preferably 30 to 70 g / 10 min, to achieve good stretchability during the spinning process. Furthermore, the melt flow rate ratio of the main component resin to the secondary component resin is preferably 0.2 ≤ [melt flow rate of secondary component resin / melt flow rate of main component resin] ≤ 1.5, more preferably 0.3 to 1.4. When the melt flow rate ratio is within these ranges, the spinnability is good, and the dispersibility of the secondary component resin becomes good, thus resulting in stable thermal adhesion.

[0053] If the biodegradable nonwoven fabric constituting this embodiment is an island fiber in which the resin, as the main component, forms a sea and the resin, as the secondary component, forms an island, then the effect of reducing the crystallization initiation temperature is significant, and therefore preferred.

[0054] [The pulling force of the filament during spinning]

[0055] In spunbond bonding, a high-speed airflow traction device utilizing air jets is typically used. The traction force can be adjusted by the amount of air introduced into the traction device. For this traction force, two strands of 0.235mm diameter nylon silk (fishing line) of the same length as the total length of the traction device (in this specification, TORAY INDUSTRIES, INC.'s "Silver Scale (No. 2 / Natural / 50m single roll)") are inserted into the traction device. The stress is measured using a spring scale connected to the nylon silk, and the traction force (mN / m) is measured by the proportionate return of the inserted nylon silk. The preferred traction force is 82–125 mN / m, more preferably 82–105 mN / m, and most preferably 87–100 mN / m. By controlling the traction force within an appropriate range, the crystallization initiation temperature and cold crystallization peak are easily kept within suitable ranges, thus reducing shrinkage due to preheating during molding and exhibiting sufficient tensile strength.

[0056] [Hot pressing conditions]

[0057] In the manufacture of the biodegradable nonwoven fabric according to this embodiment, when hot bonding is performed, a pair of embossing rollers with a textured surface on at least one surface can be used. The hot bonding is performed under the following conditions: roller temperature preferably 25–85°C, more preferably 40–70°C; linear pressure preferably 5–100 N / mm, more preferably 20–70 N / mm; and bonding area ratio preferably 4–50%, more preferably 8–40%. By performing hot bonding within the appropriate range, the bond will not detach during molding, resulting in a nonwoven fabric with good dimensional stability obtained by sufficient crystallization through short-term heating.

[0058] [Fixed-length heat setting conditions]

[0059] In the manufacture of the biodegradable nonwoven fabric of this embodiment, a fixed-length heat setting can be performed after embossing. The nonwoven fabric web, freshly spun, is heat-pressed under tension to obtain a nonwoven fabric with good surface properties and thermal elongation. This results in a molded body that does not break during molding and has a neat shape, which is therefore preferable. As for the method of performing fixed-length heat setting, conventional methods can be used, such as hot air drying, needle chain tenter drying, hot plate drying, calendering, felting roller finishing, air permeation, hot pressing, etc. As for the temperature range for performing fixed-length heat setting, it is not particularly limited to a temperature at which the resin constituting the nonwoven fabric does not adhere to the apparatus and the fibers of the nonwoven fabric are properly bonded. Preferably, it is 50°C to 95°C, more preferably 70°C to 90°C, and even more preferably 70°C to 80°C. If the temperature for fixed-length heat setting is below 95°C, the orientation crystallization of the nonwoven fabric is appropriately suppressed, the crystallization initiation temperature can be lowered, and the enthalpy heat ΔH of the cold crystallization peak can be increased. Furthermore, if the temperature for fixed-length heat setting is above 50°C, the effects achieved by the above-mentioned fixed-length heat setting are fully realized.

[0060] [Cooking]

[0061] The biodegradable nonwoven fabric of this embodiment can lower the crystallization initiation temperature and suppress thermal shrinkage during molding and processing (especially during the preheating process) by using specific curing conditions. Specifically, the above effects are easily obtained by storing the fabric at 40°C for more than 10 days.

[0062] The following describes the molded body formed by thermoforming the biodegradable nonwoven fabric of this embodiment.

[0063] The biodegradable nonwoven fabric of this embodiment can be processed by thermoforming to form a molded body. There are no particular limitations on the shape of the molded body; it can be semi-circular, cylindrical, elliptical, triangular, square, etc., depending on the intended use. If a molded body with a larger area (surface area) than the nonwoven fabric before molding is desired, the molding die can be appropriately enlarged by selecting a mold that further increases the area of ​​the nonwoven fabric before and after molding.

[0064] The molding method for biodegradable nonwoven fabric in this embodiment is not particularly limited if it includes a thermoforming process. A preheating process may be included before thermoforming, and a shape-maintaining process to maintain capacity may be included after thermoforming.

[0065] By including a preheating process before thermoforming, the temperature of the nonwoven fabric before molding can be controlled, allowing the nonwoven fabric's properties, such as storage modulus, to reach values ​​suitable for molding. The preferred temperature range for the nonwoven fabric before molding is 30–70°C, more preferably 40–60°C, and even more preferably 40–50°C. If the temperature of the nonwoven fabric before molding is above 30°C, the nonwoven fabric becomes sufficiently soft, resulting in good follow-through of the molding die during molding, thus reducing the likelihood of molding defects such as bag breakage and uneven molding. Conversely, if the temperature before molding is below 70°C, the nonwoven fabric will not shrink due to heat, making it easier to process.

[0066] In this embodiment, the biodegradable nonwoven fabric contains polylactic acid-based polymers, resulting in a very slow crystallization rate. Therefore, during molding, the shrinkage of the molded body due to residual stress from stretching the nonwoven fabric occurs before crystallization, easily leading to the formation of molded bodies with small capacity. Therefore, to achieve rapid cooling and solidification of the molded body while maintaining its shape, a shape-maintaining process is included after molding to obtain molded bodies with large capacity.

[0067] The degree of molding of the biodegradable nonwoven fabric in this embodiment is expressed by the molding index. The molding index is a value defined by the following formula (1), which is obtained by dividing the surface area of ​​the molded body by the area of ​​the planar nonwoven fabric used in the molded body before molding (the area of ​​the opening in the case of a container shape).

[0068] Molding index = (Surface area of ​​the molded body (cm²)) 2 Area of ​​the nonwoven fabric before molding (cm²) 2 ))

[0069] In this embodiment, the forming index of the biodegradable nonwoven fabric during molding is preferably 1.1 or higher, more preferably 1.1 or higher and 20 or lower, even more preferably 1.5 to 10, and most preferably 2.5 to 6. A high forming index indicates that the nonwoven fabric is significantly elongated. On the other hand, a low forming index indicates that the nonwoven fabric elongates less. Because the biodegradable nonwoven fabric of this embodiment has a high elongation rate, it is possible to produce molded articles with a high elongation rate and a high forming index. On the other hand, if the forming index is 20 or lower, the bag will not break and can be molded; if the forming index is 1.1 or higher, the contents can be filled into the container to achieve an appropriate size.

[0070] When forming the biodegradable nonwoven fabric of this embodiment, from the viewpoint of balancing the improvement of the dimensional stability and productivity of the molded body, the deformation speed is preferably 32 mm / s or more, more preferably 40 mm / s or more, even more preferably 50 mm / s or more, most preferably 105 mm / s or more, and preferably 320 mm / s or less, more preferably 140 mm / s or less.

[0071] Example

[0072] The present invention will be specifically described below through examples.

[0073] First, the measurement methods and evaluation methods used in the examples and comparative examples will be explained.

[0074] (Characteristic evaluation of biodegradable nonwoven fabrics)

[0075] (1) Weight per unit area (g / m²) 2 )

[0076] According to JIS L-1913, the total area is 1500 cm². 2 (For example, cut a nonwoven fabric sample in the manner of width 20cm × (length 25cm 3 sheets), and convert it into the mass per unit to calculate.)

[0077] (2) Bulk density (g / cm³) 3 )

[0078] The thickness (mm) of the nonwoven fabric sample under a 100g load was measured using a thickness gauge manufactured by Mitsutoyo, and calculated using the following formula:

[0079] Bulk density (g / cm³) 3 = Weight per unit area (g / m²) 2 ) / thickness (mm) / 1000.

[0080] (3) Melting point (°C)

[0081] Using a PerkinElmer DSC6000 differential scanning calorimeter, the temperature was increased at a rate of 10°C / min to a temperature exceeding the melting point of the nonwoven fabric sample. The apex of the peak corresponding to the melting peak in the resulting graph was defined as the melting point. It should be noted that multiple melting peaks may be observed due to the polylactic acid (PLA) volume ratio or the mixing of secondary resin components. The melting point referred to here is the peak at the lower temperature side corresponding to the main resin component, with its apex defined as the melting point.

[0082] (4) Crystallization initiation temperature (°C)

[0083] The crystallinity change of the nonwoven fabric sample was measured by time-division wide-angle X-ray scattering (WAXS) at 20-second intervals. The temperature at which the crystallinity increased by more than 3% relative to room temperature (e.g., from 20.0% at room temperature to 20.6%) was defined as the crystallinity initiation temperature. When the addition of secondary resins and the increase in crystallinity were divided into two stages, the temperature originating from the primary resin was used. It should be noted that the measuring apparatus / conditions are as described below.

[0084] Device: NANOPIX manufactured by Rigaku Corporation

[0085] X-ray wavelength: 0.154nm

[0086] Optical system: Point collimation (1st: 1.40mmφ, 2nd: open, guard: 0.85mmφ)

[0087] Detector: HyPix-6000 (Two-dimensional semiconductor detector)

[0088] Camera length: 122.2mm

[0089] Exposure time / measurement cycle: 10 seconds / 20 seconds

[0090] Environment around the sample chamber: vacuum

[0091] Heating conditions for samples (non-woven fabric samples): The furnace was heated from room temperature. To stabilize the temperature in the furnace, the temperature was kept at 30°C for 5 minutes, and then increased at a rate of 1°C / minute (maximum temperature 150°C).

[0092] As part of the measurement procedure, the nonwoven fabric sample, mounted in the tank, is inserted into the furnace, and heating begins. Measurements are then taken at different times starting immediately after heating begins. For data processing, the scattering pattern I(2θ,φ) measured using a two-dimensional detector is expressed by the following formula:

[0093]

[0094] {In the formula, θ: Bragg angle, φ: azimuth angle, P: polarization factor.}

[0095] A circular averaging is performed to obtain a one-dimensional scattering pattern I(2θ).

[0096] In this study, to accurately capture the changes in crystallinity associated with temperature variations and shorten the measurement cycle, transmittance measurements of the samples were not performed. Therefore, empty cell scattering correction was not performed. The temperature history within the cell was pre-measured using an empty cell and thermocouples, and it was confirmed that the temperature change within the cell was consistent with the furnace setpoint at a heating rate of 1°C / min. The changes in crystallinity of the biodegradable thermoplastic resin associated with temperature variations were calculated for each sample. For crystallinity X, the one-dimensional scattering peaks were separated into crystalline peaks and amorphous halos, and calculated using the following formula.

[0097]

[0098] In the formula, I ci : Area of ​​the i-th crystallization peak, I aiArea of ​​the amorphous halo.

[0099] Peak separation can be achieved by ensuring that each peak is sufficiently separated. In the case of PLA, as a peak separation condition, for amorphous peaks, the baseline is drawn by connecting 2θ = 5° to 2θ = 28°, and the fitting range is set to 5° < 2θ < 28°. For crystalline peaks, diffraction peaks originating from PLA crystals, observed as a function of temperature, are used. The two diffraction peaks originating from the (110) / (200) and (203) planes are fitted using Gaussian functions as a constraint condition, with the amorphous peak position fixed at 2θ = 16.9° and the full width at half maximum (FWHM) at 9.5°.

[0100] (5) Enthalpy and heat of cold crystallization ΔH (J / g)

[0101] Using a PerkinElmer differential scanning calorimeter (DSC6000), the temperature was increased at a rate of 10 °C / min to a temperature exceeding the melting point of the nonwoven fabric sample. For the exothermic peaks originating from crystallization in the resulting graphs, the peak areas were determined by differential curves in regions where thermal changes occurred.

[0102] (6) Dimensional change rate (%) in the MD direction at 80℃~140℃ obtained by mechanothermal analysis

[0103] Remove 5cm from both ends of the sample to cut out a 2mm wide and 25mm long sample with a unit area weight of ±10% as determined in (1). Use a TA Instruments TMAQ400 fixture with a film / fiber fixture on the upper part and an aluminum ball from TA Instruments on the lower part. The measurement is performed under the following conditions: initial load 0.005N, temperature rise from 30℃ to 160℃, heating rate 10℃ / min, and a holding length of 15mm. The following formula is used at 80℃ to 140℃:

[0104] Dimensional change rate (%) = Dimensional change (μm) / {Hand length (mm) × 1000} × 100

[0105] Calculate the dimensional change rate (%). Using N=3 as the reference, calculate the average value.

[0106] (7) Biodegradable (industrial compost)

[0107] Nonwoven fabric samples were composted for up to 12 weeks using the pilot-scale aerobic disintegration determination method according to ISO 16929 (JIS K 6952). Finally, the samples were passed through a 2 mm sieve, and the evaluation was based on the ratio of the weight remaining on the sieve to the weight before passing through the sieve, according to the following evaluation criteria.

[0108] [Evaluation Criteria]

[0109] ◎: Screen residue less than 5%

[0110] ○: Screen residue exceeding 5% but less than 10%

[0111] ×: Screen residue exceeds 10%.

[0112] (8) Uniform moldability (R / Ave)

[0113] A nonwoven fabric sample is installed on a molding machine with 10 columns of molding dies in the width direction. The temperature of the nonwoven fabric is set to 50°C using hot air. A cylindrical molding die (diameter 4.4cm, height 3.2cm) with a temperature of 120°C is used. The time from the moment the die contacts the nonwoven fabric until the specified depth is reached is set to 1.0 second to perform the pressing and molding. A PLA sheet is used as a cover material for heat sealing. 100 molded bodies are produced.

[0114] Cut off 1cm from the bottom of each of the molded bodies and measure their weight.

[0115] The value of R / Ave is defined using the following formula:

[0116] R(the maximum weight of 100 images minus the minimum weight) / Ave(the average weight of 100 images).

[0117] (9) Formability

[0118] Two types of cylindrical metal were used: one with a diameter of 4.4 cm and a height of 1.3 cm (13 mm), and the other with a diameter of 4.4 cm and a height of 3.2 cm (32 mm). The appearance of the molded bodies was observed when pressed using the same method as in (7), and evaluated according to the following evaluation criteria. It should be noted that the molding index is a value defined using the following formula, calculated by dividing the surface area of ​​the molded body by the area of ​​the planar nonwoven fabric used before molding (or the area of ​​the opening in the case of a container shape):

[0119] Molding index = (Surface area of ​​the molded body (cm²)) 2 Area of ​​the nonwoven fabric before molding (cm²) 2 )).

[0120] (Evaluation Criteria)

[0121] It should be noted that the number of surface fuzzes is determined by measuring the number of fuzz roots on the surface of the molded body and calculating the average value of N=10.

[0122] ◎: A molded body with a molding index of 1.9 or higher is obtained in a mold with a height of 1.3cm, and a molded body with a molding index of 3.4 or higher is obtained in a mold with a height of 3.2cm. Furthermore, out of 100 molded bodies, the number of bags broken is 1 or less, and the number of surfaces with fuzz is 3 or less.

[0123] ○: A molded body with a molding index of 1.9 or higher is obtained in a mold with a height of 1.3cm, and a molded body with a molding index of 3.4 or higher is obtained in a mold with a height of 3.2cm. However, out of 100 molded bodies, the number of broken bags is 2 or more but less than 5, or the number of surface fuzzing is 4 or more but less than 9.

[0124] △: A molded body with a molding index of 1.9 or higher was obtained in a mold with a height of 1.3cm, and a molded body with a molding index of 3.4 or higher was obtained in a mold with a height of 3.2cm. However, there are problems such as uneven surface of the molded body, uneven stretching, and more than 10 types of surface fuzzing.

[0125] ×: The object breaks and cannot be formed.

[0126] (10) Dimensional stability of the molded body (volume change during boiling water immersion)

[0127] The molded body prepared using the method described above (8) was immersed in boiling water for 1 minute and then air-dried. The volume change before and after immersion in boiling water was calculated, and the average value of N=5 was obtained. The volume change rate was used to determine the following evaluation criteria.

[0128] ◎: The volume variation of the molded body is within ±5%.

[0129] ○: The volume variation of the molded body is within ±10%.

[0130] △: The volume variation of the molded body is within ±20%.

[0131] ×: The volume variation of the molded body exceeds ±20%.

[0132] [Example 1]

[0133] Polybutylene succinate (melting point 110℃) of 10% by weight was added to polylactic acid (REVODE manufactured by Zhejiang Hisun Biotechnology Co., Ltd.) with an MFR of 15g / 10min at a temperature of 210℃. The mixture was melted and compounded using a single screw extruder. The filaments were then extruded onto a moving collecting surface using a spunbond method at a spray rate of 0.9g / min·Hole, a spinning temperature of 230℃, and a traction force of 93mN / m to produce a biodegradable long fiber mesh (circular cross section).

[0134] Next, using a pair of embossing rollers with a raised or recessed pattern on one roller surface, hot pressing was performed under the conditions of a pressing area ratio of 14%, a temperature of 55°C for both upper and lower rollers, and a roller linear pressure of 40 N / mm, resulting in a unit area weight of 100 g / m². 2 Biodegradable nonwoven fabrics.

[0135] [Example 2]

[0136] The polylactic acid was replaced with polylactic acid (Ingeo manufactured by Nature Works) with an MFR of 15 g / 10 min at 210°C, and the biodegradable nonwoven fabric was otherwise manufactured in the same manner as in Example 1.

[0137] [Examples 3-7]

[0138] The ejection volume, embossing pressure, and linear speed were varied in a manner consistent with those in Example 1, except that the biodegradable nonwoven fabric was manufactured in the same manner as in Example 1.

[0139] [Examples 8-12]

[0140] By changing the traction force and the pressing area ratio (embossing ratio), the biodegradable nonwoven fabric is manufactured in the same manner as in Example 5.

[0141] [Examples 13-15]

[0142] The roller temperature (embossing temperature) during hot pressing was set to 40, 70, and 85°C. Otherwise, the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0143] [Examples 16-21]

[0144] The polybutylene succinate (PBS) addition rate was set to 1, 3, 5, 15, 20, and 30 wt%, and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0145] [Example 22]

[0146] The resin of the secondary component was set as polybutylene adipate (PBSA), and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0147] [Example 23]

[0148] The resin used as a secondary component was polybutylene adipate terephthalate (PBAT), and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0149] [Example 24]

[0150] The resin of the secondary component was set as polycaprolactone (PCL), and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0151] [Example 25]

[0152] The resin of the secondary component was set as polyhydroxybutyrate hexanoate (PHBH), and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0153] [Example 26]

[0154] The resin of the secondary component was set as ethylene-ethyl acrylate copolymer (EEA), and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0155] [Examples 27-30]

[0156] The hot-pressing area ratio (embossing ratio) during hot pressing was set to 4, 8, 10, and 40%, and the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0157] [Examples 31-33]

[0158] The embossing pattern during hot pressing is set to needle, oval, or flat pattern, and the biodegradable long fiber nonwoven fabric is manufactured in the same manner as in Example 5.

[0159] [Examples 34-36]

[0160] The biodegradable nonwoven fabric was manufactured in the same manner as in Example 5, except that the PBS addition rate was set to 0% and the traction force was changed.

[0161] [Example 37]

[0162] The main component resin was set to nylon 4 (PA4) with an MFR of 25 g / 10 min at a temperature of 210°C, and the embossing temperature was changed to 63°C. Otherwise, the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0163] [Example 38]

[0164] The main component resin was polyglycolic acid (PGA) with an MFR of 20 g / 10 min at a temperature of 210°C. The spinning temperature was changed to 260°C and the embossing temperature was changed to 48°C. Otherwise, the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0165] [Example 39]

[0166] Polylactic acid and polybutylene succinate were melted and mixed separately using a separate extruder to form a spinning spinneret. A sheath-core type spinning spinneret was used, with polylactic acid as the core component and polybutylene succinate as the sheath component. Otherwise, the biodegradable nonwoven fabric was manufactured in the same manner as in Example 5.

[0167] [Examples 40-43]

[0168] To confirm the formability during short-term thermoforming, the biodegradable nonwoven fabric of Example 5 was used to create molded bodies with the pressing temperature set to 120°C, 120°C, 140°C, and 140°C, and the pressing time set to 0.8 seconds, 0.6 seconds, 0.3 seconds, and 0.1 seconds, respectively, and various evaluations were performed.

[0169] [Example 44]

[0170] As a short fiber, raw cotton containing 10wt% polylactic acid and 30μm monofiber diameter polybutylene succinate is used, and it is processed by a carding machine to produce a unit area weight of 150g / m². 2 The nonwoven fabric mesh was then placed on a 100-mesh wire mesh and subjected to high-pressure liquid flow treatment using a high-pressure liquid flow treatment device with jet holes of 0.08 mm diameter spaced 0.7 mm apart, to integrate the mesh into a single unit. The liquid flow jetting conditions were set to 60 kg / cm². 2 One water pressure test at 120 kg / cm 2 The water pressure is applied once. Additionally, the pressure is set to 120 kg / cm² from the opposite side. 2 The mesh was subjected to water pressure once. Then, in order to remove excess moisture from the obtained mesh, it was dried at 100°C using a hot air dryer to obtain a biodegradable nonwoven fabric.

[0171] [Example 45]

[0172] The nonwoven fabric obtained in Example 44 was hot-pressed using a pair of embossing rollers with a raised or recessed pattern on the surface of one roller. The pressing area ratio was 14%, the temperature of both the upper and lower rollers was 55°C, and the roller linear pressure was 40 N / mm. The resulting fabric had a unit area weight of 150 g / m². 2 Biodegradable nonwoven fabrics.

[0173] [Example 46]

[0174] The nonwoven fabric obtained in Example 44 was needled at a density of 300 needles / cm. 2 The needle-punching process causes the fiber web to interweave, thereby achieving a weight of 150 g / m² per unit area. 2 Biodegradable nonwoven fabrics.

[0175] [Compare Examples 1 and 2]

[0176] With unit area weights of 5 and 500 g / m² respectively 2 The linear velocity was changed in the same way as in Example 1, except that the biodegradable nonwoven fabric was manufactured.

[0177] [Compare Examples 3 and 4]

[0178] The traction force was set to 79 and 137 mN / m, and the biodegradable long-fiber nonwoven fabric was manufactured in the same manner as in Example 5. It should be noted that in Comparative Example 3, the filaments in the traction device were clogged and could not be spun.

[0179] [Comparative Example 5]

[0180] The roller temperature during hot pressing was set to 90°C. Otherwise, the biodegradable nonwoven fabric was to be manufactured in the same manner as in Example 5. However, the nonwoven fabric shrank rapidly during hot pressing, making it impossible to manufacture a nonwoven fabric.

[0181] [Comparative Example 6]

[0182] The PBS addition rate during the manufacture of biodegradable long fiber nonwoven fabric was set to 35 wt%. Otherwise, the biodegradable nonwoven fabric was to be manufactured in the same way as in Example 5, but frequent breakage prevented spinning.

[0183] [Comparative Example 7]

[0184] Polybutylene succinate (melting point 110℃) of 10% by weight was added to polylactic acid (REVODE manufactured by Zhejiang Hisun Biotechnology Co., Ltd.) with an MFR of 15g / 10min at a temperature of 210℃. The mixture was melted and compounded using a single screw extruder. The filaments were then extruded onto a moving collecting surface using a spunbond method at a spray rate of 0.9g / min·Hole, a spinning temperature of 230℃, and a traction force of 87mN / m to produce a biodegradable long fiber mesh (circular cross section).

[0185] Next, a pair of embossing rollers with raised and recessed patterns on the surface of one roller are used for hot pressing under the conditions of a pressing area ratio of 14%, a temperature of 45°C for both the upper and lower rollers, and a roller linear pressure of 30 N / mm.

[0186] The temporary crimped mesh was then stored at 30°C for 72 hours, followed by heat treatment using a felt-wrapping roller polishing machine (roller diameter 2500mm, temperature 100°C, processing speed 10m / min) to obtain a biodegradable nonwoven fabric (weight per unit area 150g / m²). 2 (Fiber diameter 30μm).

[0187] [Comparative Example 8]

[0188] The temperature of the felt-covering roller smoothing machine was set to 135°C, and the biodegradable nonwoven fabric was manufactured in the same manner as in Comparative Example 7.

[0189] [Comparative Example 9]

[0190] Polybutylene succinate with an MFR of 30 g / 10 min at 210 °C was melted and compounded using a single-screw extruder. The filaments were then extruded onto a moving collecting surface using a spunbond method at a spray rate of 0.9 g / min·Hole, a spinning temperature of 220 °C, and a traction force of 93 mN / m to produce a biodegradable long fiber mesh (circular cross-section).

[0191] Next, a pair of embossing rollers with raised and recessed patterns on the surface of one roller are used to heat press the fabric under the conditions of a pressing area ratio of 12%, a temperature of 90°C for both the upper and lower rollers, and a roller linear pressure of 40 N / mm to produce a biodegradable nonwoven fabric.

[0192] The results of Examples 1-46 and Comparative Examples 1-9 are shown in Tables 1-5 below.

[0193] [Table 1]

[0194]

[0195] [Table 2]

[0196]

[0197] [Table 3]

[0198]

[0199] [Table 4]

[0200]

[0201] [Table 5]

[0202]

[0203] Industrial availability

[0204] The biodegradable nonwoven fabric of this invention, due to its biodegradability and excellent forming uniformity and moldability, is suitable for a wide range of applications, including containers for consumer materials, containers for industrial materials, vehicle interior / exterior materials, sound insulation materials, sound absorption materials, component transport pallets, fruit and vegetable trays, food containers, seedling containers, and filters. Furthermore, the biodegradable nonwoven fabric of this invention has high elongation, allowing it to be formed into containers of complex shapes. Moreover, because it can suppress thermal shrinkage of molded articles, it is also suitable for applications requiring design flexibility in containers.

Claims

1. A biodegradable spunbond nonwoven fabric, characterized in that, It is a spunbond nonwoven fabric composed of fibers containing biodegradable thermoplastic resin, with a unit area weight of 10 g / m². 2 Above and 450g / m 2 The nonwoven fabric has a melting point that is 91°C or higher and crystallization initiation temperature that is 159°C or lower, and the nonwoven fabric has a cold crystallization enthalpy ΔH that is 1.0 J / g or higher and 20.0 J / g or lower. Furthermore, the fiber containing the biodegradable thermoplastic resin contains polylactic acid, nylon 4, or polyglycolic acid as a single component of the biodegradable thermoplastic resin; or, the fiber containing the biodegradable thermoplastic resin contains more than 70% by weight and less than 99.5% by weight of any one or more selected from the group consisting of polylactic acid, nylon 4, and polyglycolic acid as a main component, and contains more than 0.5% by weight and less than 30% by weight of any one or more selected from the group consisting of polybutylene succinate, polybutylene adipate terephthalate, polybutylene adipate succinate, polycaprolactone, polyhydroxybutyrate hexanoate, and ethylene-ethyl acrylate copolymer as a secondary component, and the fiber containing the biodegradable thermoplastic resin, when containing the secondary component, is an island fiber in which the main component forms a sea and the secondary component forms an island. Furthermore, the nonwoven fabric has a bonding area ratio of 8% or more and 40% or less. Furthermore, the dimensional change rate of the nonwoven fabric in the MD direction at 80℃~140℃, obtained by thermomechanical analysis, is greater than -20.1% and less than -4.0%.

2. A method for manufacturing a molded article, comprising the step of thermoforming the biodegradable spunbond nonwoven fabric of claim 1.

3. The manufacturing method according to claim 2, wherein, The deformation speed in the thermoforming process is above 32 mm / s and below 320 mm / s.

4. The manufacturing method according to claim 3, wherein, The deformation rate in the thermoforming process is above 105 mm / s and below 140 mm / s.

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