JPH101855A - Biodegradable short fiber nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject fabric having required biodegradability, excellent in mechanical properties, also excellent in the cooling tendency, spinnability and drawability of delivered constituent yarns, and having heat-sealing function. SOLUTION: This biodegradable nonwoven fabric is made up of alternately laminating-type conjugate short fibers each made up from a high-melting component A consisting of a biodegradable 1st aliphatic polyester and a low-melting component B consisting of a biodegradable 2nd aliphatic polyester lower in melting point than the component A. Each of the conjugate short fibers has such structure that both the high-melting and low-melting components A and B are divided, respectively, and alternately laminated on the cross-section, and also lie continuous in the direction of fiber axis and are exposed onto the fiber surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable short-fiber nonwoven fabric having biodegradability and good thread-forming properties during production, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, biodegradable nonwoven fabrics include, for example, viscose short fiber nonwoven fabric obtained by dry method or solution immersion method, cupra rayon long fiber nonwoven fabric or viscose rayon long fiber nonwoven fabric obtained by wet method, chitin Nonwoven fabrics made of natural synthetic fibers such as collagen and collagen, and spunlace nonwoven fabrics made of cotton are known. However, since these biodegradable nonwoven fabrics have low mechanical strength and are hydrophilic, the mechanical strength at the time of water absorption / wetting is remarkably reduced. Furthermore, since these nonwoven fabrics are non-thermoplastic, they have no thermoformability and are inferior in workability.

As a biodegradable nonwoven fabric which solves such a problem, Japanese Patent Application Laid-Open No. 5-93318 or Japanese Patent Application Laid-Open No.
JP-195407 discloses a nonwoven fabric using a biodegradable thermoplastic polymer. However, in these, the spun yarn is inferior in the cooling property, spinnability, and stretchability, and is inferior in mechanical properties and flexibility of the obtained nonwoven fabric because it becomes a full-melt type in a hot pressing process and the like. there were.

[0004] Such a problem occurs in the process of producing a biodegradable nonwoven fabric because, in general, a polymer having biodegradability has a low melting point and a low crystallization temperature and a low crystallization rate. That is, in the cooling of the spun yarn discharged from the spinneret, in the winding step, adhesion occurs between the yarns, and only an undrawn yarn inferior in uniformity can be obtained,
In the subsequent drawing step, yarn breakage occurs, or even if drawing is possible, only short fibers having poor mechanical properties can be obtained. And the nonwoven fabric which consists of such a short fiber becomes inferior to a mechanical characteristic and formation.

In conventional biodegradable short fibers,
In general, the cross section of the fiber is a single type, a single hollow type or a composite core-sheath type, and only one component covers the entire surface of the fiber. Accordingly, if the cooling property and spinnability of the spun yarn are emphasized using a biodegradable polymer having a relatively high melting point and crystallization temperature, the resulting nonwoven fabric will be inferior in decomposition performance, and conversely, When biodegradation performance is emphasized using a biodegradable polymer having a relatively low melting point and crystallization temperature, the spun yarn has poor cooling, spinnability and stretchability.

[0006]

SUMMARY OF THE INVENTION The present invention solves such a problem and is excellent in biodegradability.
An object of the present invention is to provide a biodegradable short-fiber nonwoven fabric having excellent cooling property, spinnability, and stretchability of a spun yarn at the time of production and having a heat bonding function, and a method for producing the same.

[0007]

In order to achieve this object, the present invention has the following features. (1) Formed from a high melting point component composed of a first aliphatic polyester having biodegradability and a low melting point component composed of a second aliphatic polyester having a lower melting point than the high melting point component. The composite staple fiber comprises a plurality of high-melting point components and a plurality of low-melting point components alternately laminated in the fiber cross section. A biodegradable short-fiber nonwoven fabric, which is exposed on the surface.

(2) A high melting point component composed of a first aliphatic polyester having biodegradability and a low melting point component composed of a second aliphatic polyester having a lower melting point than the high melting point component. A plurality of high-melting-point components and low-melting-point components are alternately laminated in the cross section of the fiber, and the high-melting-point component and the low-melting-point component are continuous in the fiber axis direction and are exposed on the fiber surface. By melt-spinning, then drawing the spun yarn, applying mechanical crimp to the obtained drawn yarn, cutting it into a predetermined length to form short fibers, and carding the short fibers. A method for producing a biodegradable short fiber nonwoven fabric, comprising forming a short fiber web and holding the short fiber web in a predetermined form.

According to the present invention, a plurality of high-melting-point components and low-melting-point components are alternately arranged in a cross section of the short fibers constituting the nonwoven fabric.
Moreover, since the high melting point component and the low melting point component are continuous in the fiber axis direction and are exposed on the fiber surface, the high melting point component, which is inferior in biodegradability but excellent in cooling, spinnability and stretchability, is used. Along with being finely divided, a low-melting point component which is inferior in cooling property, spinnability and stretchability but excellent in biodegradability can be finely divided. This allows for cooling, spinnability,
A nonwoven fabric excellent in both stretchability and biodegradability can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the short fibers constituting the non-woven biodegradable nonwoven fabric of the present invention will be described. The short fiber applied in the present invention is composed of a high melting point component composed of a first aliphatic polyester having biodegradability and a low melting point composed of a second aliphatic polyester having a biodegradability having a lower melting point than the high melting point component. It is a conjugate short fiber formed from a melting point component.

The first and second biodegradable aliphatic polyesters constituting the high melting point component and the low melting point component include:
For example, poly (α) such as polyglycolic acid and polylactic acid
-Hydroxy acids) or copolymers composed of repeating unit elements constituting them. In addition, poly (ω-hydroxyalkanoate) such as poly (ε-caprolactone) and poly (β-propiolactone) further includes
Poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxycaproate, poly-3-hydroxyheptanoate, poly-3-
Poly (β-hydroxyalkanoates) such as hydroxyoctanoate, and the repeating unit elements constituting them, and poly-3-hydroxyvalerate and poly-4-
A copolymer with a repeating unit element constituting hydroxybutyrate is exemplified. Further, as the one consisting of a condensation polymer of a diol and a dicarboxylic acid, for example, polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene acetate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate , Polyhexamethylene sebacate, polyneopentyl oxalate, or copolymers composed of repeating units constituting these. Further, a plurality of these aliphatic polyesters can be blended and used. Among the above aliphatic polyesters, polybutylene succinate, polyethylene succinate and polybutylene adipate are particularly preferred from the viewpoints of spinnability and biodegradability.
More particularly, a copolymerized polyester obtained by copolymerizing ethylene succinate or butylene adipate with butylene succinate as a main repeating unit is preferable. In the present invention, of the two types of polymers selected from the above aliphatic polyesters, the polymer having a higher melting point is a high melting point component, and the polymer having a lower melting point is a low melting point component. .

By the way, aliphatic polyesters are generally
The higher the melting point, the better the cooling, spinnability, and stretchability of the spun yarn, but the higher the crystallinity, the poorer the biodegradability. Conversely, the lower the melting point, the better the spun yarn. Although inferior in cooling, spinnability and stretchability, it has excellent biodegradability due to low crystallinity. For example, in the case where the fiber cross section is a single phase of a high melting point component having a relatively high melting point, the desired biodegradability cannot be obtained although the spinning property and the formation of a nonwoven fabric are excellent. On the other hand, when the fiber cross section is a single phase of a low melting point component having a relatively low melting point, the spun yarn is inferior in the cooling property during melt spinning, and a nonwoven fabric cannot be obtained.

According to the present invention, as described below, the biodegradability is inferior in the cross section of the fiber, but the cooling property and spinnability,
Along with subdividing the high-melting-point component with excellent stretchability, the low-melting-point component, which is inferior in the cooling and spinnability and stretchability of the spun yarn but has excellent biodegradability, is subdivided. By alternately laminating in the fiber cross section,
It is possible to obtain a nonwoven fabric excellent in all of the cooling property and spinnability, stretchability and biodegradability of the spun yarn.

Therefore, in the present invention, the difference in melting point between the high melting point component and the low melting point component is preferably 5 ° C. or more, more preferably 10 ° C. or more. If the difference in melting point between the high melting point component and the low melting point component is less than 5 ° C., the fiber cross section approaches a full fusion type as in the case of a single phase. Cannot satisfy the cooling effect, spinnability, stretchability and biodegradability of the present invention.

[0015] From this fact, polybutylene succinate is used as the high melting point component, and ethylene succinate or butylene succinate is used as the low melting point component such that the copolymerization ratio of butylene succinate is 70 to 90 mol%. It is preferable to use a copolymerized polyester obtained by copolymerizing butylene adipate. If the copolymerization ratio of butylene succinate is less than 70 mol%, the biodegradability is excellent, but the cooling property, spinnability and stretchability of the spun yarn are poor, and the desired short fiber can be obtained. It will not be. Conversely, if it exceeds 90 mol%, the spun yarn has excellent cooling properties, spinnability and stretchability, but is inferior in biodegradability and is not the object of the present invention.

In the present invention, the above-mentioned aliphatic polyester applied to the high melting point component and the low melting point component includes:
The number average molecular weight is about 20,000 or more, preferably 40,
Those having a molecular weight of 000 or more, more preferably 60,000 or more are good in terms of the spinning properties and the properties of the obtained yarn. Further, in order to increase the degree of polymerization, a chain extended with a small amount of diisocyanate or tetracarboxylic dianhydride may be used.

In the present invention, for example, a matting agent, a pigment, a light stabilizer and an antioxidant may be added to both or one of the high melting point component and the low melting point component, if necessary. It can be added within a range that does not impair the effect.

In particular, in the short fibers used in the present invention, it is preferable that a nucleating agent is added to at least the low melting point component among the constituent components. Addition of a nucleating agent can prevent adhesion between spun yarns even for a low-crystalline polymer that is hard to solidify after melt spinning.

Here, the crystal nucleating agent is not particularly limited as long as it is not a powdered inorganic substance and does not dissolve in a melt, but talc, calcium carbonate, titanium oxide, boron nitride, silica gel, Magnesium oxide or the like is usually used, and among them, talc, titanium oxide or a mixture thereof is particularly preferably used.

As for the nucleating agent, the amount of the nucleating agent added to the high melting point component was QA (% by weight) and the amount of the nucleating agent added to the low melting point component was QB (% by weight). sometimes,
It is preferable that it is added so as to satisfy the formulas (1) and (2). [(ΔTA + ΔTB) / 100] −2 / 3 ≦ QA + QB ≦ [(ΔTA + ΔTB) / 100] +4 (1) QA ≦ QB (2) where ΔTA = melting point of high melting point component−high melting point component Crystallization temperature ≧ 35 ΔTB = melting point of low melting point component−crystallization temperature of low melting point component ≧
If the total amount of the crystal nucleating agent QA + QB (% by weight) exceeds the upper limit defined by the formula (1), the spun yarn has a high cooling effect, but the spinnability is reduced and the obtained short fibers are obtained. As a result, the mechanical performance of the nonwoven fabric is inferior, which is not preferable. Conversely, if the total amount of the crystal nucleating agent QA + QB (% by weight) is lower than the lower limit defined by the formula (1), the cooling property of the spun yarn is reduced, and adhesion between the spun yarns occurs. Then, it becomes difficult to obtain the target nonwoven fabric. Also, when the addition amount QA (% by weight) of the nucleating agent in the high melting point component is larger than the addition amount QB (% by weight) of the nucleating agent in the low melting point component, the cooling property of the high melting point component is reduced. Although it is further improved, the cooling property of the low-melting point component is lowered, and this is not preferable because adhesion between spun yarns is likely to occur.

In the formula (1), ΔT is the difference between the melting point and the crystallization temperature of each component. In the spinning process, the smaller the ΔT, the better the cooling of the spun yarn. In the polymer of the present invention, ΔT is usually as large as 35 or more. However, the cooling of the spun yarn can be effectively promoted by adding a nucleating agent.

In the present invention, the viscosities of the high melting point component and the low melting point component are not particularly limited, but the viscosity of the high melting point component is preferably lower than that of the low melting point component. this is,
Generally, in composite spinning of a thermoplastic resin, this is because a low-viscosity component acts to cover a high-viscosity component. That is, in the present invention, by lowering the viscosity of the high melting point component having a high degree of crystallinity, which is inferior in biodegradability, the exposure ratio of the low melting point component segment on the fiber surface is reduced, and the spun yarn is removed. Adhesion can be prevented and spinnability and stretchability can be improved. However, if the viscosity is too low, the high melting point component will cover most of the low melting point component segment, so that the adhesion can be improved but the biodegradation performance is inferior, and the object of the present invention. Not something.

Accordingly, the melt flow rate value (hereinafter referred to as MFR value) of the polymer applied in the present invention is 20 to 70 g / 10 min for the high melting point component and 15 to 70 g / 10 min for the low melting point component.
It is preferably 50 g / 10 minutes. However, the MFR value in the present invention is measured according to the method described in ASTM-D-1238 (E). MF of high melting point component
When the R value is less than 20 g / 10 min and / or the MFR value of the low melting point component is less than 15 g / 10 min, the spun yarn is not smoothened smoothly because the viscosity is too high, resulting in poor operability. As a result, the resulting fibers have a large fineness and poor uniformity. Conversely, MF of high melting point component
MF with R value of 70 g / 10 min and / or low melting point component
If the R value exceeds 50 g / 10 minutes, the viscosity is so low that not only the composite cross section becomes unstable, but also yarn breakage occurs in the spinning process, impairing operability and mechanical properties of the obtained nonwoven fabric. Is inferior. For these reasons, the MFR value of the high melting point component is 25 to 65 g / 10
More preferably, the low melting point component has an MFR value of 18 to 45 g / 10 minutes.

Next, the fiber cross-sectional shape of the conjugate short fiber applied to the present invention will be described. In the alternate lamination type composite section of the present invention, a plurality of high-melting point components and low-melting point components are alternately laminated in the cross section of the fiber, and the high melting point component and the low melting point component are continuous in the fiber axis direction and the fiber surface. Must be exposed. By laminating a plurality of high-melting-point components and low-melting-point components, for example, even if the low-melting-point component is a polymer inferior in cooling, spinnability and stretchability, it is spun by an adjacent high-melting-point component. It is possible to improve the cooling property, spinnability and stretchability of the spun yarn. In addition, even if the high melting point component is a polymer with poor biodegradability, the biodegradability of the adjacent low melting point component is excellent, so if the low melting point component decomposes over time, the high melting point component is left as a flake with very small fineness. This results in excellent biodegradability as a nonwoven fabric.
Further, it is necessary that both the high melting point component and the low melting point component are continuous in the fiber axis direction in order to enhance the stability of the fiber cross section, the spinning property, and the mechanical properties of the fiber.
In addition, it is necessary that both of the two components are exposed on the fiber surface in order to improve the cooling property, spinnability and stretchability of the spun yarn and to promote and control the biodegradability.

In the fiber cross section of the conjugate short fiber applied to the present invention, the total number of laminations of the high melting point component and the low melting point component is 4 or more, and the single fiber fineness of the conjugate short fiber is 1.5 to 1.5.
It must be 10 denier. If the total number of layers is less than 4, the spun yarn is inferior in cooling property, spinnability, stretchability and decomposition performance. That is, in the alternate lamination section of the present invention, the larger the individual layers, the worse the cooling property, spinnability, stretchability and decomposition performance of the spun yarn. In addition, the total number of layers needs to be controlled based on the fineness of the conjugate short fibers. That is,
In the case of a fineness of 1.5 d (denier) or the like, it is not preferable that the total number of laminations is too large because not only the cross-sectional shape becomes unstable but also yarn breakage easily occurs during the yarn making process. Conversely, in the case of a fineness of 10d or the like, if the total number of laminations is too small, the cooling and stretching properties of the spun yarn are inferior, and since the size of each component is large, the decomposition performance is inferior. Becomes For this reason, the total number of layers is more preferably 4 to 16. The size of the laminated pieces may be individually different. Further, when the single fiber fineness of the conjugate short fiber is less than 1.5 d, instability of resin flow in the spinneret, frequent occurrence of yarn breakage in the spinning process, decrease in production amount, instability of fiber cross-sectional shape, etc. It is not preferable because it occurs. On the other hand, if it exceeds 10d, the spun yarn is inferior in cooling performance and poor in decomposition performance. For this reason, it is more preferable that the single yarn fineness is 2d to 8d.

The composite fiber applied to the present invention preferably has a composite ratio of the high melting point component / low melting point component of 1/3 to 3/1 (weight ratio). If the compounding ratio is out of this range, the cooling properties, spinnability, stretchability, and biodegradability of the spun yarn cannot all be satisfied, and further, instability of the fiber cross-sectional shape is induced. Is not preferred. For example, when the composite ratio of the high-melting-point component / low-melting-point component exceeds 1/3, the resulting biodegradability is excellent, but the cooling property and the opening property of the spun yarn are poor. Conversely, when the composite ratio of the high melting point component / the low melting point component exceeds 3/1, the spun yarn is excellent in the cooling property and the spreadability, but is inferior in the biodegradability. Further, for example, if the high melting point component is a polymer having poor biodegradability, the biodegradation rate can be promoted by increasing the composite ratio of the low melting point component. For this reason, the ratio is more preferably 1/2 to 2/1 (weight ratio).

Next, a method for producing the biodegradable nonwoven fabric of the present invention will be described. Production of the biodegradable nonwoven fabric of the present invention,
It can be carried out using an ordinary composite spinning device. First, the above-mentioned aliphatic polyester having biodegradability, that is, polybutylene succinate as a high-melting component and butylene succinate having a copolymerization ratio of butylene succinate as a low-melting component of 70 to 90 mol% are mainly repeated. The copolymerized polyester as a unit is melted separately as a suitable material, and individually weighed so that the composite ratio of the high melting point component / low melting point component becomes 1/3 to 3/1 (weight ratio). The spun yarn is discharged from a composite spinneret capable of forming an alternately laminated fiber cross-sectional structure that satisfies the number of segments of each component and the fineness of a single yarn.

FIG. 1 is a schematic view of a spinneret for obtaining such an alternately laminated conjugate fiber. Here, reference numeral 1 denotes an intermediate plate having an introduction hole 2 for a high melting point component and an introduction hole 3 for a low melting point component. Reference numeral 4 denotes a base. The base 4 joins the high-melting-point component and the low-melting-point component discharged from the introduction holes 2 and 3 at the portion 5 to form a composite flow. Then, the bonded composite flow is introduced into the guide hole 7 in which the stationary kneading element 6 is provided, and is spun from the discharge hole 8 as an alternately laminated composite flow. The number of layers in the fiber cross section of the obtained conjugate fiber is determined by the number of stationary kneading elements 6. The spinneret for obtaining the alternately laminated conjugate fibers is not limited to such a configuration.

FIGS. 2, 3, and 4 illustrate the cross-sectional structure of the alternately laminated conjugate fiber according to the present invention. Here, A indicates a high melting point component, and B indicates a low melting point component.

The spun fibers are cooled by a known cooling device. Next, the undrawn yarn is wound up by a take-up roll, and the undrawn yarn is drawn at a predetermined draw ratio between drawing rolls having different peripheral speeds. Here, the number of stretching rolls and the stretching temperature in the stretching step may be appropriately selected. For example, when stretching is performed with a large fineness, it is necessary to increase the number of stretching rolls and further perform thermal stretching. Then
After the obtained drawn yarn is crimped by a stuffer box, it can be cut into a predetermined length to obtain short fibers.
Although the above-described method is a two-step method, short fibers can also be obtained by a one-step method, that is, a so-called spin draw method in which undrawn yarn is continuously drawn without being wound up.

In the present invention, as described above,
It is preferable to add a nucleating agent to the polymer used. Thereby, the cooling property of the spun yarn during the melt spinning can be improved. The nucleating agent is added in the polymerization step or the melting step. In this case, it is preferable to disperse the yarn as uniformly as possible in order to improve the mechanical performance and uniformity of the obtained yarn.

Next, the obtained short fibers are carded by a card machine to prepare a short fiber web having a predetermined basis weight.
Depending on the degree of arrangement of the constituent fibers, the web may be any one of a parallel web arranged in the traveling direction of the card machine, a web in which the parallel webs are cross-laid, a random web arranged randomly, or a semi-random web arranged in the middle of both. It may be. In particular, for those used for clothing, the strength of
It is preferable to use a card web having a lateral strength ratio of approximately 1/1.

The short fiber web thus formed is subjected to a partial heat-pressing treatment or a three-dimensional entanglement treatment at a temperature not higher than the melting point of the low-melting point component, thereby maintaining the short fiber web in a predetermined form. The biodegradable short-fiber nonwoven fabric of the present invention can be obtained.

In the case of maintaining the form of a short fiber web by a partial hot pressing treatment, a method of forming a point fusion zone between fibers using a heated embossing roll and a metal roll having a smooth surface. Alternatively, a method is employed in which a high-frequency ultrasonic wave is applied on a pattern roll using an ultrasonic fusion device to form a point fusion area between fibers in the pattern portion. The term "partial thermal pressure welding" as used herein means that the low-melting-point components are hot-pressed between the constituent fibers to maintain the form of the web, and at least the high-melting-point components are not fused and the constituent fibers are completely fused. It refers to thermal pressure welding that can prevent wearing, and by making such partial thermal welding,
Biodegradability and flexibility can be exhibited while maintaining a predetermined nonwoven fabric form.

When using a heated embossing roll,
The surface temperature of the roll, that is, the processing temperature, must be lower than the melting point of the low melting point component. If the melting point of the low melting point component is exceeded, not only the polymer adheres to the heat-welding apparatus and the operability is remarkably impaired, but also the texture of the nonwoven fabric becomes hard and a flexible nonwoven fabric cannot be obtained. More preferably, the processing temperature is (Tm-25) when the melting point of the low melting point component is (Tm) ° C.
C. to (Tm) .degree. C.

When using an ultrasonic welding device, an ultrasonic oscillator called a normal horn having a frequency of about 20 kHz,
An apparatus comprising a pattern roll having a point-like or band-like convex protrusion on the circumference is employed. The pattern roll is disposed below the ultrasonic oscillator, and the short fiber web can be partially heat-sealed by passing the short fiber web between the ultrasonic oscillator and the pattern roll. The number of convex protrusions provided on the pattern roll may be one or more, and when the number of the protrusions is plural, any of parallel or staggered arrangement may be used.

The partial heat-pressing treatment may be performed in either a continuous step or a separate step. Further, for the heat-pressing treatment, any of the above-described heated embossing roll or ultrasonic fusing device may be selected, but depending on the use application of the nonwoven fabric, a medical / hygiene material or the like which particularly requires flexibility is used. When an ultrasonic fusion device is used as a general living related material such as a wiping cloth, a nonwoven fabric having excellent performance can be obtained.

On the other hand, in the present invention, when the short fiber web is formed into a nonwoven fabric by a three-dimensional entanglement treatment, a known method using a pressurized column water flow or a needle can be applied. In the case of the three-dimensional confounding treatment, since heating is not performed, a nonwoven fabric having more excellent flexibility can be obtained.

[0039]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

In the following examples, each physical property value was measured by the following method.

Melt flow rate (MFR) value (g /
10 minutes); measured at a temperature of 190 ° C. according to the method described in ASTM-D-1238 (E).

Melting point (° C.): extreme value of a melting endothermic curve obtained by using a differential scanning calorimeter DSC-2 manufactured by Perkin Elmer, measuring the sample weight at 5 mg and the heating rate at 20 ° C./min. Was given as the melting point (° C.).

Crystallization temperature (° C.): Using a differential scanning calorimeter DSC-2 manufactured by PerkinElmer, and weighing a sample of 5 m
g, the crystallization temperature (° C.) was defined as the temperature at which the extreme value of the solidification heat generation curve obtained by measuring the temperature drop rate at 20 ° C./min.

Weight per unit area (g / m ² ): Ten sample pieces each having a sample length of 10 cm and a sample width of 10 cm were prepared from the sample in the standard condition, and the water content was equilibrated. Then, the weight (g) of each sample piece was weighed. And convert the average of the obtained values to unit area,
The basis weight (g / m ² ) was used.

Cooling property: The spun yarn was visually observed and evaluated according to the following four grades. A: No cohesive yarn is observed. ；: A slight amount of cohesive yarn was observed.

Δ: Cohesive yarn is present, and fibers are partially bundled. X: Most adhered.

Spinnability: Evaluated by the following two steps. ；: No yarn breakage, and good spinning operability. X: Thread breakage occurs frequently and spinning operability is poor.

Stretchability: Evaluated by the following two steps. ；: No stretching fuzz is generated, and stretching operability is good. X: Stretching fuzz occurs frequently and stretching is impossible.

・ Strong (kg / 2.5cm width); JIS-
It was measured according to the method described in L-1096A. That is, a sample piece 1 having a sample length of 10 cm and a sample width of 2.5 cm
A zero point was created, and a tensile speed of 1 was set for each sample piece in the longitudinal direction of the nonwoven fabric using a constant-speed extension-type tensile tester (Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd.).
It was stretched at 0 cm / min, and the average value of the obtained load values at cutting was defined as the strength (kg / 5.0 cm width).

Biodegradability: embedded non-woven fabric in soil, 6
If the nonwoven fabric does not retain its shape after a month, or if the strength is reduced to 50% or less of the initial strength value before embedding even if it retains its shape, the biodegradation performance is The biodegradability was evaluated as poor (; x) if the strength was more than 50% of the initial strength before embedding. Example 1 As a high melting point component, polybutylene succinate having an MFR value of 30 g / 10 min and a melting point of 114 ° C. and a crystallization temperature of 75 ° C., and a low melting point component having an MFR value of 20 g / 10 min and a melting point of 99 ° C. Using a copolymer of butylene succinate / ethylene succinate = 85/15 mol% at a crystallization temperature of 49 ° C., alternately laminated conjugate fibers were melt-spun.

That is, the two components were individually weighed so that the composite ratio of the high-melting component / low-melting component was 1/1 (weight ratio), and then the temperature was adjusted to 180 using a separate extruder-type melt extruder. Using a spinneret having a fiber cross section (round shape, total number of laminations: 8) as shown in FIG. 2, which was melted at 0 ° C., alternately laminated conjugate fibers were melt-spun at a single hole discharge rate of 1.23 g / min. . After cooling the spun yarn with a known cooling device, the yarn was taken up by a winding roll so as to have a winding speed of 800 m / min, and wound up as an undrawn yarn. Then, a plurality of the undrawn yarns are aligned and drawn by a known drawing machine so that the drawing ratio becomes 3.6 times, crimped by a stuffer box, and then 51 mm in length. Then, short fibers having a single yarn fineness of 4.0 denier were obtained.

Next, the obtained short fibers were carded to form a web, and the web was hot pressed to obtain a biodegradable short fiber nonwoven fabric having a basis weight of 30 g / m ² . The hot pressing conditions were as follows: a hot embossing roll provided with an engraving pattern having an area of 0.6 mm ² , a pressing contact density of 20 points / cm ² , and a pressing area ratio of 15%, and a metal roll having a smooth surface. And the hot pressing temperature was 95 ° C. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time.

[0053]

[Table 1]

Example 2 A cross section of a round fiber as shown in FIG. 2 was used. In addition, the single hole discharge amount of the spinneret is set to 0.4
0 g / min. The film was drawn at a draw ratio of 3.1 times, and the cut length of the fiber was 38 mm. The other conditions were the same as in Example 1 to produce alternately laminated conjugate short fibers. The obtained short fibers had a single yarn fineness of 1.5 denier. Then, the short fiber was formed into a web under the same conditions as in Example 1 and subjected to hot pressing to give a basis weight of 30 g / m 2.
^Thus, a biodegradable nonwoven fabric of No. ² was obtained. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 3 The total number of laminations was 16 in a round fiber cross section as shown in FIG. In addition, the single hole discharge amount of the spinneret is 3.58 g.
/ Min. The film was drawn at a draw ratio of 4.2 times, and the cut length of the fiber was 101 mm. The other conditions were the same as in Example 1 to produce alternately laminated conjugate short fibers. The obtained short fibers had a single yarn fineness of 10.0 denier. Then, the short fiber was formed into a web under the same conditions as in Example 1 and subjected to hot pressing to give a basis weight of 30 g / m 2.
^Thus, a biodegradable nonwoven fabric of No. ² was obtained. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 4 Under the same conditions as in Example 1, an alternately laminated conjugate short fiber having a single yarn fineness of 4.0 denier was obtained. A nonwoven web was formed under the same conditions as in Example 1. Then, the nonwoven web was partially heat-pressed using an ultrasonic heat fusion machine to obtain a biodegradable short fiber nonwoven fabric. At the time of ultrasonic welding, a roll provided with an engraved pattern having an area of 0.6 mm ² , a press contact density of 20 points / cm ² , and a press contact area ratio of 15% was used.
The frequency was set to 9.15 kHz. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 5 Under the same conditions as in Example 1, a multi-layer conjugate short fiber having a single yarn fineness of 4.0 denier was obtained. A nonwoven web was formed under the same conditions as in Example 1. Then, the nonwoven web was formed into a nonwoven fabric using a high-pressure liquid flow treatment device. That is, the short fiber web was placed on a 70-mesh wire net moving at a moving speed of 20 m / min and subjected to a pressurized liquid flow treatment. In this pressurized liquid flow treatment, the injection holes having a hole diameter of 0.12 mm have a hole interval of 0.1 mm.
A columnar water flow was applied in two stages from a position 50 mm above the short fiber web using a pressurized liquid flow treatment device arranged in a line at 6 mm. In the first stage treatment, the pressure of the water stream was 30 kg / cm ² G, and in the second stage treatment, the pressure was 70 kg / cm ² G. The processing of the second stage is as follows.
First, after the web is applied four times from the front side, the web is inverted,
It was applied four times from the back side. Next, excess water was removed from the obtained nonwoven fabric using a mangle roll, and then dried using a hot air drier at a temperature of 90 ° C., and the fabric was densely and three-dimensionally entangled to a weight of 30 g / m ^2. Was obtained. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 6 Using the same high melting point component and low melting point component as in Example 1,
Using a spinneret having a fiber cross section as shown in FIG. 3 (hollow, total number of laminations: 8), the single-hole discharge amount was 1.13 g / min, and the composite ratio of the high melting point component / low melting point component was 1/1 ( (Weight ratio), alternately laminated conjugate fibers were melt-spun. Other spinning conditions were the same as in Example 1. After cooling the spun yarn with a known cooling device, it was wound up under the same conditions as in Example 1 to obtain an undrawn yarn. Then, a plurality of the undrawn yarns are drawn and aligned, drawn by a known drawing machine so that the drawing ratio becomes 3.3 times, crimped by a stuffer box, and then length of 51 mm. Then, short fibers having a single yarn fineness of 4.0 denier were obtained.

Next, the obtained short fibers were carded to form a web, and the web was hot-pressed to obtain a biodegradable nonwoven fabric having a basis weight of 30 g / m ² . The conditions of the heat pressing were the same as in Example 1. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 7 Using the same high melting point component and low melting point component as in Example 1,
Using a spinneret having a fiber cross section as shown in FIG. 4 (three leaves, total number of laminations: 8), the single hole discharge amount was 1.16 g / min, and the composite ratio of high melting point component / low melting point component was 1/1. As the weight ratio, alternately laminated conjugate fibers were melt-spun. Other spinning conditions were the same as in Example 1. After cooling the spun yarn with a known cooling device, it was wound up under the same conditions as in Example 1 to obtain an undrawn yarn. Then, a plurality of the undrawn yarns are aligned, drawn by a known drawing machine so that the drawing ratio becomes 3.4 times, and crimped by a stuffer box. Then, short fibers having a single yarn fineness of 4.0 denier were obtained.

Next, the obtained short fibers were carded to form a web, and the web was hot-pressed to obtain a biodegradable nonwoven fabric having a basis weight of 30 g / m ² . The conditions of the heat pressing were the same as in Example 1. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 8 The same polybutylene succinate as in Example 1 was used as the high melting point component, and the MFR value was 20 g / 1 as the low melting point component.
A nonwoven fabric composed of alternately laminated conjugate fibers was manufactured using a butylene succinate / butylene adipate = 80/20 (mol%) copolymer polyester having a melting point of 94 ° C. and a crystallization temperature of 48 ° C. in 0 minutes.

That is, the two components are melted at a spinning temperature of 170 ° C. so that the composite ratio of the high melting point component / low melting point component becomes 1/1 (weight ratio), and the fiber cross section shown in FIG. Using a spinneret having a round shape and a total of 8 laminated layers, alternately laminated conjugate fibers were melt-spun at a single hole discharge rate of 1.13 g / min. After cooling the spun yarn with a known cooling device,
It was wound up under the same conditions as in Example 1 to obtain an undrawn yarn. Then, a plurality of the undrawn yarns are drawn and aligned, drawn by a known drawing machine so that the drawing ratio becomes 3.3 times, crimped by a stuffer box, and then length of 51 mm. Then, short fibers having a single yarn fineness of 4.0 denier were obtained.

Then, the obtained short fibers were carded to form a web, and the web was hot-pressed to obtain a biodegradable nonwoven fabric having a basis weight of 30 g / m ² . The heat welding conditions are
The heat welding temperature was set to 87 ° C., and the other conditions were the same as in Example 1. The yarn operability at this time, the physical properties of the obtained nonwoven fabric,
Table 1 shows the biodegradation performance. Example 9 Using the same high melting point component and low melting point component as in Example 1,
Using a spinneret having a fiber cross section as shown in FIG. 2 (round shape, total number of laminations: 8), the single-hole discharge amount was 1.35 g / min, and the composite ratio of the high melting point component / low melting point component was 1/1. As the weight ratio, alternately laminated conjugate fibers were melt-spun. After the spun yarn is cooled by a known cooling device, hot drawing is performed at a draw ratio of 3.8 times between a winding roll having a speed of 800 m / min and a drawing roll having a speed of 3040 m / min. In other words, a drawn yarn was obtained by a so-called spin draw method. And
A plurality of the drawn yarns were aligned and crimped in a stuffer box, and then cut to a length of 51 mm to obtain short fibers having a single yarn fineness of 4.0 denier.

Next, the obtained short fibers were carded to form a web, and the web was hot-pressed to obtain a biodegradable nonwoven fabric having a basis weight of 30 g / m ² . The conditions of the heat pressing were the same as in Example 1. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Example 10 In the same manner as in Example 1 except that a nucleating agent was added to the high-melting point component and the low-melting point component and the stretching ratio was set to 3.5, a short-fiber nonwoven fabric composed of alternately laminated conjugate fibers was prepared. Manufactured. That is, a masterbatch containing 20% by weight of talc / titanium oxide = 1/1 (weight ratio) having an average particle size of 1.0 μm as a crystal nucleating agent is based on a high melting point polymer and a low melting point polymer. Create in advance,
The masterbatch and the corresponding polymer are blended, and the nucleating agent to be added to the high melting point component is 0.1%.
The raw material was prepared such that the nucleating agent added to the low melting point component was 2% by weight and the nucleating agent was 1.0% by weight. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Comparative Example 1 Under the same conditions as in Example 1, a short-fiber nonwoven web composed of alternately laminated conjugate fibers having a single-fiber fineness of 4 denier was formed. Then, this web was hot-pressed at a processing temperature of 105 ° C. which was equal to or higher than the melting point of the low melting point component, to obtain a biodegradable nonwoven fabric having a basis weight of 30 g / m ² . Table 2 shows the yarn operability at this time.

[0060]

[Table 2]

Comparative Example 2 The same polybutylene succinate as in Example 1 was used as the high melting point component, and the MFR value was 20 g / l as the low melting point component.
A copolymerized polyester of butylene succinate / butylene adipate = 60/40 (mol%) having a melting point of 84 ° C. and a crystallization temperature of 22 ° C. in 0 minutes was used. That is, the copolymerization molar ratio of butylene succinate / butylene adipate was out of the preferred range in the present invention.

Then, the mixture was melted at a spinning temperature of 160 ° C. by setting the composite ratio of the high melting point component / low melting point component to 1/1 (weight ratio),
Using a spinneret having a fiber cross section as shown in FIG. 2 (round shape, total number of laminations: 8), alternately laminated conjugate fibers were melt-spun at a single hole discharge rate of 1.23 g / min. After cooling the spun yarn with a known cooling device, the yarn was taken up by a winding roll so as to have a winding speed of 800 m / min, and wound up as an undrawn yarn. Table 2 shows the yarn operability at this time. Comparative Example 3 The same high melting point component and low melting point component as in Example 1 were used. However, the spinneret used had a core-sheath type having a round fiber cross-section unrelated to the present invention. Then, the high melting point component becomes the core portion and the low melting point component becomes the sheath portion, the composite ratio of both is set to 1/1 (weight ratio), and the core-sheath is discharged at a single hole discharge rate of 1.23 g / min. The composite fibers of the mold were melt spun. Other spinning conditions were the same as in Comparative Example 1.

After the spun yarn was cooled by a known cooling device, it was taken up by a take-up roll at a winding speed of 800 m / min and wound up as an undrawn yarn. Table 2 shows the yarn operability at this time. Comparative Example 4 The same high melting point component and low melting point component as in Example 1 were used. However, the spinneret used was such that the fiber cross-section unrelated to the present invention had a parallel type (round shape, total number of laminations: 2). Then, the composite ratio of both was set to 1/1 (weight ratio), and the parallel composite fibers were melt-spun at a single hole discharge rate of 1.23 g / min. Other spinning conditions were the same as in Comparative Example 1.

After the spun yarn was cooled by a known cooling device, it was taken up by a take-up roll at a winding speed of 800 m / min and wound up as an undrawn yarn. Table 2 shows the yarn operability at this time. Comparative Example 5 A single-phase nonwoven fabric was produced using only the high melting point component of Example 1 and a spinneret having a round fiber cross section. That is, the high melting point component was melted at 180 ° C., and a single-phase fiber was melt-spun under the condition of a single hole discharge rate of 1.30 g / min.

After the spun yarn was cooled by a known cooling device, it was taken up by a take-up roll at a winding speed of 800 m / min and wound up as an undrawn yarn. And
A plurality of these undrawn yarns are drawn and aligned, drawn by a known drawing machine so that the draw ratio becomes 3.8 times, crimped in a stuffer box, and then cut into a length of 51 mm. As a result, short fibers having a single yarn fineness of 4.0 denier were obtained.

Then, the obtained short fibers were carded to form a web, and the web was hot-pressed to obtain a biodegradable nonwoven fabric having a basis weight of 30 g / m ² . The heat welding conditions are
The heat welding temperature was 107 ° C., and the other conditions were the same as in Example 1. Table 1 shows the spinning operability, physical properties and biodegradability of the obtained nonwoven fabric at this time. Comparative Example 6 A single-phase nonwoven fabric was produced using only the low melting point component of Example 1 and a spinneret having a round fiber cross section. That is, the high melting point component was melted at 170 ° C., and a single-phase fiber was melt-spun under the condition of a single hole discharge rate of 1.13 g / min.

After the spun yarn was cooled by a known cooling device, it was taken up by a take-up roll at a winding speed of 800 m / min and wound up as an undrawn yarn. Table 2 shows the yarn operability at this time.

As is clear from Table 1 above, Example 1
Since the nonwoven fabric obtained in the above uses the alternately laminated conjugate fiber based on the present invention, the cooling property of the spun yarn, spinnability,
The stretchability was excellent, and the mechanical performance of the nonwoven fabric was excellent. Further, when this nonwoven fabric was buried in the soil for 6 months, excavated and observed thereafter, it was confirmed that the nonwoven fabric did not retain its form and had good biodegradability.

In Example 2, an alternately laminated conjugate fiber having a smaller number of layers but a smaller fineness than that of Example 1 is used. It was excellent in cooling property, spinnability, stretchability, and mechanical properties of the nonwoven fabric. The biodegradability of the nonwoven fabric was also good.

In Example 3, although the fineness is larger than that in Example 1, the spun yarn is used in the same manner as in Example 1 since the alternately laminated conjugate fiber having a larger number of layers is applied. The cooling and stretching properties of the strip were excellent. Although the mechanical performance of the nonwoven fabric was slightly inferior to that of Example 1, good results were obtained for the biodegradation performance.

In the fourth embodiment, the same web obtained in the first embodiment is integrated by using an ultrasonic welding machine.
Although the mechanical performance was slightly inferior, a nonwoven fabric having better flexibility than that of Example 1 was obtained. In addition, it was confirmed that it had good biodegradability.

In the fifth embodiment, the same web as that obtained in the first embodiment is integrated by high-pressure liquid flow treatment, so that the mechanical performance is slightly inferior, but the flexibility is higher than that in the first embodiment. An excellent non-woven fabric was obtained. In addition, it was confirmed that it had good biodegradability.

In Example 6, the same high melting point component and low melting point component as those in Example 1 were used, and a composite fiber having a hollow alternately laminated cross section was used. However, it was confirmed that the composition had better biodegradability. That is, the obtained nonwoven fabric is
When buried in the soil for months and dug out and observed, it did not retain its form as a nonwoven fabric,
Good biodegradability was observed.

In Example 7, the same high melting point component and low melting point component as those of Example 1 were used, and a composite fiber having an alternately laminated cross section of three leaves was applied. It was recognized that it had a better biodegradability despite its fineness.

In Example 8, the copolymerization ratio of the low melting point component was higher than that of Example 1, but the copolymerization ratio was within the preferred range in the present invention. Since the laminated conjugate fiber was used, the cooling and stretching properties of the spun yarn were good. Although the obtained nonwoven fabric was slightly inferior in mechanical performance to that of Example 1, it was recognized that it had better biodegradability.

In the ninth embodiment, a so-called spin draw method is adopted, in which the same high-melting point component and the low-melting point component as those in the first embodiment are used, and the drawing is performed without winding once as an undrawn yarn. The spun yarn has good cooling and drawing properties, and the obtained nonwoven fabric has excellent mechanical performance and good biodegradability. Admitted.

In Example 10, since the crystal nucleating agent is contained in the polymer, the cooling property, spinnability and stretchability of the spun yarn are as follows.
It was even better than in Example 1. This nonwoven fabric was also excellent in mechanical performance and biodegradability.

On the other hand, in Comparative Example 1, the same web as that of Example 1 was prepared by using 105 ° C. which was higher than the melting point of the low melting point component.
Since the heat-sealing was performed at ℃, the web adhered to the embossing roll, significantly impairing the operability, and the target nonwoven fabric could not be obtained.

In Comparative Example 2, since the copolymerization molar ratio of the low melting point component was beyond the preferred range in the present invention, the melting point and the crystallization temperature of the low melting point component were too low, and the alternate lamination according to the present invention was carried out. The spun yarns adhered to each other in spite of using the conjugated fiber, and the stretchability was deteriorated, so that the intended nonwoven fabric could not be obtained.

In Comparative Example 3, although the same high-melting-point component and low-melting-point component as in Example 1 were used, since the fiber cross-section was a core-sheath type irrelevant to the present invention, the cooling property was poor. Since the low melting point component was disposed on the sheath side, the cooling property, spinnability and stretchability of the spun yarn were all poor, and the desired nonwoven fabric could not be obtained.

Comparative Example 4 uses the same high-melting-point component and low-melting-point component as in Example 1, but has a fiber cross section outside the scope of the present invention (round type, total number of laminations: 2). Therefore, the cooling property, spinnability, and stretchability of the spun yarn were all poor, and the desired nonwoven fabric could not be obtained.

In Comparative Example 5, the same component as the high melting point component of Example 1 was used alone, and the fiber cross section was a single-phase type unrelated to the present invention. Although the cooling property, spinnability and stretchability of the sample were good, the biodegradability was remarkably inferior, and the desired nonwoven fabric could not be obtained.

In Comparative Example 6, the same component as the low melting point component of Example 1 was used alone, and the fiber cross section was a single-phase type unrelated to the present invention. Was inferior in cooling property, spinnability and stretchability, and the desired nonwoven fabric could not be obtained.

[0084]

According to the present invention, the required biodegradability can be achieved, and the mechanical properties of the nonwoven fabric, the cooling property of the spun yarn, the spinnability, the stretchability, and the heat bonding function can be improved. The present invention can provide a biodegradable nonwoven fabric having the same and a production method thereof.

The biodegradable nonwoven fabric of the present invention includes diapers, sanitary products and other medical and sanitary materials, wipes such as disposable towels and wiping cloths, disposable packaging materials,
It is suitable as a living-related material such as a household / business bag for collecting garbage and other waste treatment materials, or as an industrial material represented by agriculture, horticulture and civil engineering. Moreover, this nonwoven fabric has biodegradability and is completely decomposed and disappears after its use, which is beneficial from the viewpoint of protecting the natural environment, or it can be reused, for example, by composting it into fertilizer. Therefore, it is also useful from the viewpoint of resource reuse.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a spinneret for obtaining an alternately laminated conjugate fiber according to the present invention.

FIG. 2 is a model diagram of a fiber cross section of an example of an alternately laminated conjugate fiber according to the present invention.

FIG. 3 is a model diagram of a fiber cross section of another example of the alternately laminated conjugate fiber according to the present invention.

FIG. 4 is a model diagram of a fiber cross section of still another example of the alternately laminated conjugate fiber according to the present invention.

[Explanation of symbols]

 A High melting point component B Low melting point component

Claims (10)

[Claims] 1. A high melting point component comprising a biodegradable first aliphatic polyester and a low melting point component comprising a biodegradable second aliphatic polyester having a lower melting point than the high melting point component. This composite staple fiber has a plurality of high-melting point components and low-melting point components alternately laminated in the fiber cross section, and the high-melting point component and the low-melting point component are continuous in the fiber axis direction. And a biodegradable short-fiber nonwoven fabric, which is exposed on the fiber surface. 2. A high-melting-point component is polybutylene succinate, and a low-melting-point component is a copolyester having butylene succinate as a main repeating unit and a copolymerization ratio of butylene succinate of 70 to 90 mol%. The biodegradable short fiber nonwoven fabric according to claim 1, wherein 3. The non-woven biodegradable nonwoven fabric according to claim 1, wherein the low melting point component is a copolymerized polyester obtained by copolymerizing ethylene succinate or butylene adipate with butylene succinate. 4. The total number of layers of the high melting point component and the low melting point component is 4 or more, and the single fiber fineness of the composite fiber is 1.5 to 1.5.
The biodegradable short-fiber nonwoven fabric according to any one of claims 1 to 3, wherein the nonwoven fabric is 10 denier. 5. The composite ratio of a high melting point component / low melting point component is 1 /
2. The weight ratio is 3 to 3/1 (weight ratio).
5. The non-woven biodegradable nonwoven fabric according to any one of items 1 to 4. 6. The raw material according to claim 1, wherein a nucleating agent is added to at least the low melting point component of the low melting point component and the high melting point component. Degradable short fiber non-woven fabric. 7. A high melting point component comprising a first aliphatic polyester having biodegradability and a low melting point component comprising a second aliphatic polyester having a biodegradability having a lower melting point than the high melting point component. A plurality of high-melting-point components and low-melting-point components are alternately laminated on the fiber cross section, and the high-melting-point component and the low-melting-point component are continuous in the fiber axis direction and are exposed to the fiber surface. Melt spinning, then stretching the spun yarn, applying mechanical crimp to the obtained stretched yarn, cutting it into a predetermined length to form short fibers, and carding the short fibers to shorten them. A method for producing a biodegradable short fiber nonwoven fabric, comprising forming a fiber web and holding the short fiber web in a predetermined form. 8. The short fiber web is subjected to a partial heat pressing treatment with an embossing roll at a temperature not higher than the melting point of the low melting point component to maintain a predetermined form.
A method for producing the biodegradable short-fiber nonwoven fabric according to the above. 9. The method for producing a biodegradable short-fiber nonwoven fabric according to claim 7, wherein the short fiber web is subjected to an ultrasonic fusion treatment to maintain a predetermined form. 10. The short fiber web is subjected to a three-dimensional entanglement treatment to maintain a predetermined form.
A method for producing the biodegradable short-fiber nonwoven fabric according to the above.