JPH06212548A - Biodegradable latent-crimping conjugate short fiber and its nonwoven fabric - Google Patents

Abstract

PURPOSE:To provide biodegradable nonwoven fabric having excellent mechanical strength, dimensional stability, stretchability, bulkiness, flexibility and hot- bonding performance and suitable as a raw material for hygienic material and life-relating material. CONSTITUTION:The objective fiber is a biodegradable latent-crimping eccentric core-sheath conjugate short fiber having a core part composed of a biodegradable thermoplastic polymer component having high melting point and a sheath part composed of a biodegradable thermoplastic polymer component having a melting point lower than that of the core part. As an alternative, the conjugate fiber is a biodegradable latent-crimping side-by-side conjugate short fiber produced by bonding a biodegradable thermoplastic polymer component having high melting point to a biodegradable thermoplastic polymer component having low melting point in side-by-side state. The nonwoven fabric is composed of conjugate short fibers having a crimp number of >25/25mm and partly heat- bonded or three-dimensionally interlocked with each other.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention provides a non-woven fabric having biodegradability, excellent mechanical strength, dimensional stability, stretchability and bulkiness, rich flexibility, and thermal adhesiveness. The present invention relates to a suitable composite staple fiber and a nonwoven fabric thereof.

[0002]

2. Description of the Related Art Conventionally, viscose rayon short fiber non-woven fabric obtained by a dry method or a solution dipping method, Kyupra rayon long fiber non-woven fabric obtained by a wet spun bond method, viscose rayon long fiber non-woven fabric, chitin, atelocollagen, etc. Various biodegradable non-woven fabrics such as non-woven fabrics made of natural chemical fibers and spunlace non-woven fabrics made of Kotton are known. However, these conventional biodegradable non-woven fabrics have a low mechanical strength of the constituent material of the non-woven fabric and are hydrophilic, so that the mechanical strength is significantly decreased when they are absorbed by water and wet. There are various problems such as poor stability, poor flexibility, and lack of thermal adhesiveness because the material itself is non-thermoplastic.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above problems and has biodegradability, excellent mechanical strength, dimensional stability, stretchability and bulkiness, rich flexibility, and thermal bonding. The present invention is to provide a composite short fiber suitable for obtaining a nonwoven fabric having properties and a nonwoven fabric thereof.

[0004]

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems. That is, the present invention provides an eccentric core-sheath type composite short fiber in which the core portion is composed of a biodegradable thermoplastic polymer component having a high melting point and the sheath portion is composed of a biodegradable thermoplastic polymer component having a lower melting point than the polymer. The present invention also provides a biodegradable latent crimpable conjugate short fiber characterized by having latent crimping ability. The present invention also relates to a bonded type composite short fiber comprising a biodegradable thermoplastic polymer component having a high melting point and a biodegradable thermoplastic polymer component having a lower melting point than the polymer, which are bonded in a bonding type. It is a gist of a biodegradable latent crimpable conjugate short fiber characterized by having a latent crimping ability. In the present invention, the core part is made of a biodegradable thermoplastic polymer component having a high melting point, the sheath part is made of a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer, and the number of crimps is 25 / Two
It is a gist of a non-woven fabric, which is composed of eccentric core-sheath type composite short fibers having a crimp of 5 mm or more, and the constituent fibers are partially heat-bonded to each other. Further, the present invention comprises a biodegradable thermoplastic polymer component having a high melting point and a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer, which are bonded to each other in a bonding type, and the number of crimps is 25 / 25
It is a gist of a non-woven fabric characterized by being composed of laminated composite short fibers having a crimp of not less than mm, and the constituent fibers being partially heat-bonded to each other. Further, in the present invention, the core part is composed of a high melting point biodegradable thermoplastic polymer component, and the sheath part is composed of a biodegradable thermoplastic polymer component having a lower melting point than the above polymer, and the number of crimps is 25 / 25 mm
The gist of the present invention is a non-woven fabric comprising the eccentric core-sheath type composite staple fibers having the above crimps, and the constituent fibers being three-dimensionally entangled. further,
The present invention comprises a biodegradable thermoplastic polymer component having a high melting point and a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer, which are bonded to each other in a bonding type, and the number of crimps is 25/25 mm.
The gist of the present invention is a non-woven fabric, which is composed of the laminated composite short fibers having the above crimps, and the constituent fibers are three-dimensionally entangled.

Next, the present invention will be described in detail. The biodegradable thermoplastic polymer in the present invention is a thermoplastic aliphatic polyester polymer having biodegradability, and is made of polyglycolic acid or polylactic acid such as poly (α-hydroxy acid). Polymers or their copolymers, poly (ω-hydroxyalkanoates) such as poly (ε-caprolactone), poly (β-propiolactone), and poly-3-hydroxypropionate , Poly-3-hydroxybutyrate, poly-3-
Poly (s) such as hydroxycaprolate, poly-3-hydroxyheptanoate, poly-3-hydroxyoctanoate and copolymers thereof with poly-3-hydroxyvalerate and poly-4-hydroxybutyrate. β-hydroxyalkanoate). Examples of the polycondensate of glycol and dicarboxylic acid include polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, Examples thereof include polyhexamethylene sebacate, polyneopentyl oxalate, and copolymers thereof. Furthermore, the aliphatic polyester, polycapramide (nylon 6), polytetramethylene adipamide (nylon 4)
6), polyhexamethylene adipamide (nylon 6
6), polyundecanamid (nylon 11), polylaurolactamide (nylon 12), and the like aliphatic polyester amide-based copolymers which are copolycondensates with aliphatic polyamides. In the present invention, a thermoplastic polymer other than those described above can be used as the biodegradable thermoplastic polymer as long as it has biodegradability. In the present invention, in addition to the above-mentioned biodegradable thermoplastic polymer, various additives such as matting agents, pigments, light stabilizers, heat stabilizers, and antioxidants may be added as necessary. Can be added within a range that does not impair the effects of the present invention.

In the present invention, the composite staple fiber made of the biodegradable thermoplastic polymer has a melting point selected from the polymers different from 3 ° C. to 150 ° C. 2
Consisting of two polymer components, the core consisting of a high melting point biodegradable thermoplastic polymer component, and the sheath consisting of a lower melting point biodegradable thermoplastic polymer component To have an eccentric core-sheath type composite form in which both polymer components are arranged as described above, or a high melting point biodegradable thermoplastic polymer component and a lower melting point biodegradable thermoplastic polymer component. And are joined so as to have a composite structure of a pasting type and have latent crimping ability. In this composite short fiber, the difference in melting point between both polymer components is 3
It is preferable that a non-woven fabric is produced by using a fiber obtained by using a fiber having a temperature of less than 0 ° C. and is subjected to heat treatment to form a non-woven fabric because not only a low-melting point polymer component but also a high-melting point polymer component is softened and melted. Therefore, in the present invention,
The melting point difference is 3 ° C. or higher, preferably 5 ° C. or higher, more preferably 10 ° C. or higher. On the other hand, if the difference in melting point exceeds 150 ° C., the difference in melting point between both polymer components will be too different, and it will be difficult to control the spinning temperature in the spinning nozzle pack when composite spinning is performed using both polymers. . In the present invention, when the low melting point biodegradable thermoplastic polymer having a melting point of 60 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher is used, a short-term polymer having the low melting point polymer component is used. When a non-woven fabric is formed using fibers, it is preferable because the non-woven fabric can have a certain heat resistance. In this composite short fiber, the composite ratio, that is, the weight ratio of the low melting point polymer component to the high melting point polymer component is preferably 1/5 to 5/1. When the ratio of the low melting point polymer component to the high melting point polymer component 1 exceeds 5, the strength of the short fibers decreases, or the stretchability and bulkiness of the non-woven fabric obtained by using the short fibers deteriorates. On the other hand, if the ratio of the low melting point polymer component to the high melting point polymer component 5 is less than 1, the nonwoven fabric obtained by using this short fiber is Both are not preferable because the strength is lowered in the heat-bonded portion between the constituent fibers, or the stretchability and bulkiness of the non-woven fabric are deteriorated. Therefore, in the present invention, the composite ratio is 1/5 to 5 /. 1 preferably 2 /
3 to 3/2.

As described above, the composite short fibers are joined so that the high-melting point polymer component and the low-melting point polymer component have an eccentric core-sheath type composite form or a laminated type composite form. In addition, it has latent crimping ability, and when it has such a composite morphology, it undergoes relaxation heat treatment at a temperature in the vicinity of the melting point of the low-melting thermoplastic polymer component to make the latent crimps visible, and thus the crimps are crimped. Crimps of several 25/25 mm or more are developed. Therefore, when a short fiber in which this latent crimp is exposed is used as a non-woven fabric, the non-woven fabric can be provided with elasticity and bulkiness.

The composite short fibers in the present invention have a monofilament fineness of 1.0 to 20 denier, and if the monofilament fineness is less than 1.0 denier, the card passing property in producing a card web is improved. Or the web obtained by using this short fiber has many irregularities,
On the other hand, if the single fiber fineness exceeds 20 denier, the nonwoven fabric obtained by using the short fibers has a coarse and hard texture and is inferior in quality.

The nonwoven fabric in the present invention is composed of the above-mentioned composite short fibers in which the latent crimps as described above are actualized and crimps of 25 crimps / 25 mm or more are developed, and the constituent fibers are partially formed. It is heat-bonded to, and is composed of the composite short fibers in which the above crimps are expressed, and the constituent fibers are three-dimensionally entangled. This non-woven fabric has 25/25 crimps
Since it has a crimp of mm or more, it has excellent stretchability and bulkiness. Further, this non-woven fabric is one in which partial thermal bonding points are formed between the constituent fibers by a known thermal bonding treatment, and three-dimensional entanglement is formed between the constituent fibers by a known so-called high pressure liquid flow treatment. The shape of the non-woven fabric is maintained by these partial thermal bonding or three-dimensional entanglement, and the non-woven fabric exhibits excellent mechanical strength and dimensional stability. The non-woven fabric exhibits excellent flexibility.

The nonwoven fabric composed of the above-mentioned composite short fibers in the present invention preferably has a basis weight of 10 g / m ² or more. This non-woven fabric has a basis weight of 10 g / m
^When it is less than ² , the strength of the non-woven fabric itself is low, the texture of the non-woven fabric is rough, or the quality thereof is poor, or the handling property when producing the non-woven fabric is poor, and the productivity thereof is lowered, which is not preferable.

The short fibers in the present invention can be efficiently produced by the following method. That is,
According to a conventional method, two kinds of polymers having different melting points selected from the above biodegradable thermoplastic polymers having a melting point of 3 ° C. or more and 150 ° C. or less are melt-composite-spun into an eccentric core-sheath type or a laminating type. After unwinding and spinning, the spun yarn is cooled with a cooling air stream or cooling water, and then once wound into an undrawn long fiber yarn,
Alternatively, it may be continuously drawn without being wound once, and subjected to cold drawing or hot drawing in one step or two or more steps, and a predetermined mechanical crimp is applied to the obtained drawn long fiber yarn using, for example, a stuffing box. It can be obtained by cutting to a predetermined length after applying a predetermined crimp by heat shrinking treatment.

The spinning temperature during melt spinning depends on the melting point and the degree of polymerization of the polymer used, but is usually 120 to 300 ° C.
Is desirable. If the spinning temperature is less than 120 ° C, melt extrusion of the polymer becomes difficult, while the spinning temperature is 3
If the temperature exceeds 00 ° C, the thermal decomposition of the polymer will be so remarkable that high-strength fibers cannot be obtained, either of which is not preferable. The total draw ratio when drawing an undrawn long fiber yarn is
Depending on the strength level of the target short fiber, it is usually 2.0-
It is 4.0 times, whereby short fibers having a tensile strength of 3.0 g / denier or more can be obtained.

The non-woven fabric made of the short fibers in the present invention can be efficiently produced by a known so-called short fiber method. That is, according to a conventional method, two polymers having different melting points selected from the biodegradable thermoplastic polymers having a melting point of 3 ° C. or more and 150 ° C. or less are melt-composited and spun into a spun yarn. After cooling, the drawn long-fiber yarn is given a crimp, and then cut into a predetermined length to obtain short fibers. The obtained short fibers are used as raw cotton and a carding machine is used. Carding to create a card web, heat-bonding the resulting card web to partially bond the constituent fibers together, and then subjecting it to relaxation heat treatment to reveal the latent crimps of the constituent fibers. Can be obtained. Alternatively, it can be obtained by subjecting the obtained card web to a high-pressure liquid flow treatment to three-dimensionally entangle the constituent fibers with each other and then subjecting it to a relaxation heat treatment to reveal the latent crimps of the constituent fibers.

A publicly known method can be used for partially heat-bonding the web. For example, there is a method of passing a web between rollers that include a heated embossing roller and a metal roller having a smooth surface, a method of using a hot air drying device, or a method of using an ultrasonic fusing device. When the fibers existing in the embossed pattern part are partially heat-bonded by using the heated embossing roller,
The pressure contact area ratio of the embossing roller is set to 5 to 50%, and if the pressure contact area ratio is less than 5%, the mechanical strength of the non-woven fabric is reduced and the dimensional stability is reduced. On the other hand, if the pressure contact area ratio exceeds 50%, the nonwoven fabric becomes rigid and the flexibility is impaired, which is not preferable. Also, the roller temperature is usually set to a temperature lower by about 5 to 50 ° C. than the melting point of the low melting point thermoplastic polymer, and by appropriately selecting this temperature, the adhesive force between fibers is high, that is, mechanical strength is high. Excellent strength and dimensional stability,
Moreover, it is possible to obtain a non-woven fabric that is highly flexible. The embossing pattern when using the heat embossing roller is not particularly limited as long as the pressure contact area ratio is within the range of 5 to 50%, and is round, elliptical, rhombic, triangular, T-shaped, well. Any shape such as a mold may be used. When the fibers are partially heat-bonded to each other at the crossing points of the fibers by using a hot air dryer, the treatment temperature is usually higher than or equal to the melting point of the low melting point thermoplastic polymer, although it depends on the treatment time. The temperature is preferably about 10 ° C. lower than the melting point of the thermoplastic polymer.
The partial heat-bonding treatment using, for example, a hot embossing roller, a hot air drying device or an ultrasonic fusing device may be a continuous process or a separate process.

When the web is subjected to the high pressure liquid flow treatment, a known method can be adopted. For example, using a device in which a large number of injection holes having a hole diameter of 0.05 to 1.0 mm, particularly 0.1 to 0.4 mm are arranged, the injection pressure is 5 to 150 mm.
There is a method of ejecting a high-pressure liquid of kg / cm ² G from the ejection hole. The injection holes are arranged in rows in a direction orthogonal to the direction of travel of the web. This treatment may be performed on one side or both sides of the web. In particular, in the case of one-side treatment, the injection holes are arranged in a plurality of rows and the injection pressure is lowered in the front stage and increased in the rear stage. As a result, it is possible to obtain a non-woven fabric having a uniform and dense entangled form and a uniform texture. Generally, water or hot water is used as the high-pressure liquid. The distance between the injection hole and the web is 1 to 15
It is good to have cm. When this distance is less than 1 cm, the texture of the web is disturbed, while when this distance exceeds 15 cm, the impact force when the liquid flow collides with the web is reduced and the three-dimensional entanglement is not sufficiently performed. Is also not preferable.
This high pressure liquid flow treatment may be either a continuous process or a separate process. After the high pressure liquid stream treatment, excess moisture is removed from the web. A known method can be adopted for removing the excess water. For example,
Excessive water is removed to some extent using a squeezing device such as a mangle roll, and then residual water is removed using a drying device such as a continuous hot air dryer.

When the web is subjected to a relaxation heat treatment to reveal the latent crimp of the constituent fibers, a known method can be adopted. For example, it is a method of performing relaxation heat treatment on the web using a heating device such as a hot air drying device. When the web is subjected to relaxation heat treatment using a hot air dryer, the treatment temperature depends on the treatment time, but it is usually preferable to set the treatment temperature to a temperature lower by about 5 to 30 ° C. than the melting point of the low melting point thermoplastic polymer. . The relaxation heat treatment using a hot air dryer, for example, may be a continuous process or a separate process.

[0017]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples, each characteristic value was measured by the following method. Melting point (℃): Differential scanning calorimeter DS manufactured by Perkin Elma
Using a C-2 type, the measurement is performed at a temperature rising rate of 20 ° C./min,
The temperature that gives the extreme value in the obtained melting endothermic curve was taken as the melting point. Melt flow rate value (g / 10 minutes): ASTM D1
It was measured according to the method described in 238 (L). Short fiber tensile strength (g / denier): JIS-L-10
It was measured according to the method described in 13. Nonwoven fabric KGSM tensile strength (kg): JIS-L-10
It was measured according to the method described in 96A. That is, 10 sample pieces having a sample length of 10 cm and a sample width of 5 cm were prepared, and a constant speed extension type tensile tester (Tensilon UTM manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the longitudinal direction of the nonwoven fabric.
4-1-100) was used for elongation at a tensile speed of 10 cm / min, and the average value of the load values (kg) at cutting obtained was converted per unit weight per 100 g / m ^{2 of} KGSM tensile strength (k).
g). Crimp number of non-woven fabric constituent fibers (pieces / 25 mm): An enlarged photograph of the non-woven fabric constituent fibers was taken using a scanning electron microscope to determine the number of crimps.

Example 1 A polyethylene succinate polymer having a melting point of 102 ° C. and a melt flow rate value of 5 g / 10 min was used as a low melting point component in the sheath portion, and the melting flow rate value was 5 g / 1 at a melting point of 118 ° C.
A 0-minute polybutylene succinate polymer was used as the high melting point component of the core, both polymers were melted, and the spinning temperature was passed through a spinneret having 36 composite spinning holes with a hole diameter of 0.5 mm.
Melt composite spinning into an eccentric core-sheath type under the conditions of 30 ° C. and a composite ratio (weight ratio) of 1/1, the spun yarn is cooled using a cooling air flow having a temperature of 20 ° C., and then an oil agent is applied, Winding speed 10
It was once wound at 00 m / min to obtain an undrawn yarn. Then,
The total draw ratio of the obtained unstretched yarn was set to 3.8 and the temperature was adjusted to 6
One-stage hot drawing was performed using a heating roll at 0 ° C, and the resulting drawn yarn was used with a stuffing box for 18/2
Apply 5mm mechanical crimp, cut into 51mm length,
An eccentric core-sheath type composite staple fiber having a single fiber fineness of 2.0 denier was obtained. The resulting composite short fibers have a tensile strength of 3.9 g.
/ Denier and had practically sufficient mechanical strength. Further, when the short fibers were buried in soil for 2 months and then taken out and observed, it was found that the form of the fibers disappeared and that they had excellent biodegradability.

Example 2 Melting point is 102 ° C. and melt flow rate is 10 g / 10
Minute polyethylene succinate polymer as a low melting point component, and a polybutylene succinate polymer having a melting point of 118 ° C. and a melt flow rate value of 5 g / 10 minutes as a high melting point component. Through a spinneret with 36 6 mm side-by-side composite spinning holes, the spinning temperature was 205 ° C and the compounding ratio (weight ratio) was 1
Melt-composite spinning to a bonding type under the condition of / 1, and the spun yarn was cooled using a warm air stream with a temperature of 40 ° C, and then an oil agent was applied, and it was once wound at a winding speed of 800 m / min. An undrawn yarn was obtained. Next, the undrawn yarn thus obtained was subjected to one-stage hot drawing using a heating roll at a temperature of 60 ° C. with a total draw ratio of 3.8, and the resulting drawn yarn was made into 18 yarns by using a stuffing box. A mechanical crimp of 25 mm was applied and cut into a length of 51 mm to obtain a bonded type composite short fiber cotton having a single fiber fineness of 3.0 denier. The resulting composite short fibers had a tensile strength of 3.6 g / denier and had practically sufficient mechanical strength. In addition, this short fiber
After burying it in soil for a month and then taking it out and observing it, it was confirmed that it had lost its morphology as a fiber and had excellent biodegradability.

Example 3 A card web having a basis weight of 38 g / m ² was prepared by carding using the cotton short fiber obtained in Example 1 with a carding machine, and the obtained card web was heated at a temperature of Is 85 ° C
The fibers were partially heat-bonded by being passed through an embossing roll having a heating area of 18% and a smoothing roll at the same temperature, and then subjected to relaxation heat treatment using a hot air dryer at a temperature of 90 ° C. , A non-woven fabric was obtained. The obtained non-woven fabric is KG
The SM tensile strength was 10.9 kg / 5 cm in the longitudinal direction, 7.2 kg / 5 cm in the transverse direction, and the number of crimps was 35 pieces / 25 mm, and the mechanical strength, dimensional stability, stretchability and bulkiness were excellent. . Further, when this non-woven fabric was embedded in soil for 2 months and then taken out and observed, it was confirmed that the non-woven fabric had lost its morphology and had excellent biodegradability.

Example 4 The short fiber cotton obtained in Example 2 was used as raw cotton and carded using a carding machine to prepare a card web having a basis weight of 30 g / m ² , and the obtained card web was heated at a temperature of Is 90 ° C
The fibers were partially heat-bonded by passing them through an embossing roll having a contact area ratio of 18% and a smooth roll at the same temperature, and then subjected to a relaxation heat treatment using a hot air dryer at a temperature of 95 ° C. , A non-woven fabric was obtained. The obtained non-woven fabric is KG
SM tensile strength is 10.6kg / 5cm in the longitudinal direction, 7.1kg / 5cm in the transverse direction, and the number of crimps is 35 pieces / 25mm. It has excellent mechanical strength, dimensional stability, stretchability, bulkiness, and flexibility. It was rich. Further, when this non-woven fabric was embedded in soil for 2 months and then taken out and observed, it was confirmed that the non-woven fabric had lost its morphology and had excellent biodegradability.

Example 5 The short fiber cotton obtained in Example 1 was used as raw cotton and carded using a carding machine to prepare a card web having a basis weight of 38 g / m ² , and the obtained card web was 80 The fibers were placed on a mesh net of mesh and subjected to a high-pressure liquid flow treatment to entangle the constituent fibers three-dimensionally. As the high-pressure liquid flow treatment, a high-pressure columnar water flow treatment device in which injection holes having a hole diameter of 0.12 mm are arranged in a three-group arrangement with a hole interval of 0.6 mm, and a water pressure of 65 kg is used.
A columnar water stream was applied from above the web under the condition of / cm ² . This treatment was performed three times from the front and back of the web. Then, after removing excess water from the obtained treated web with a mangle roll, the web was dried with a hot air dryer at a temperature of 75 ° C., and further with a hot air dryer at a temperature of 108 ° C. The fibers were partially heat-bonded and subjected to relaxation heat treatment to obtain a nonwoven fabric. The resulting non-woven fabric has a KGSM tensile strength of 12.1k in the longitudinal direction.
g / 5cm, lateral direction 8.3kg / 5cm, crimp number 37
The number of pieces / 25 mm was excellent in mechanical strength, dimensional stability, stretchability, and bulkiness, and was also highly flexible. Also,
When this non-woven fabric was embedded in soil for 2 months and then taken out and observed, it was confirmed that the non-woven fabric had lost its form and had excellent biodegradability.

[0023]

The biodegradable latent crimpable composite staple fiber of the present invention comprises a biodegradable thermoplastic polymer component having a high melting point in the core and a biodegradation having a melting point lower than that of the polymer in the sheath. Of the above-mentioned polymer having a high melting point and a biodegradable thermoplastic polymer component having a high melting point and a melting point lower than that of the polymer. The biodegradable thermoplastic polymer component is bonded so as to have a laminated composite form, and has latent crimping ability. It has biodegradability, mechanical strength, dimensional stability, and stretchability. It is suitable for obtaining a non-woven fabric that has excellent properties and bulkiness, is highly flexible, and has thermal adhesiveness. The non-woven fabric using this composite short fiber has the above-mentioned excellent properties and is a material for sanitary materials such as diapers and sanitary products, disposable towels, wiping cloths, base cloths for pad materials, household or It is suitable as a material for daily life-related materials such as dust collection bags for business use and other waste treatment materials. Moreover, this non-woven fabric is useful from the viewpoint of protecting the natural environment because it eventually decomposes and disappears completely if left in an environment where many microorganisms are present, such as soil or water, after use, or, for example, by composting. Since it can be reused as fertilizer, it is useful from the viewpoint of resource reuse.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location D02G 1/00 Z 3/02 ZAB D04H 1/46 Z 7199-3B (72) Inventor Takashi Inagaki Kyoto Central Research Institute, Unitika Co., Ltd., 23, Uji-kozakura, Uji-shi, Japan

Claims (8)

[Claims] 1. An eccentric core-sheath type composite staple fiber having a core made of a biodegradable thermoplastic polymer component having a high melting point and a sheath made of a biodegradable thermoplastic polymer component having a lower melting point than the polymer. A biodegradable latent crimpable composite staple fiber characterized by having a latent crimping ability. 2. A bonded composite short fiber comprising a biodegradable thermoplastic polymer component having a high melting point and a biodegradable thermoplastic polymer component having a lower melting point than the polymer, which are bonded in a bonding type. And a biodegradable latent crimpable composite short fiber characterized by having a latent crimping ability. 3. The core portion is composed of a high melting point biodegradable thermoplastic polymer component, and the sheath portion is composed of a biodegradable thermoplastic polymer component having a lower melting point than the polymer, and the number of crimps is 25/25 mm.
A non-woven fabric comprising the eccentric core-sheath type composite short fibers having the above crimps, and the constituent fibers are partially heat-bonded to each other. 4. A biodegradable thermoplastic polymer component having a high melting point and a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer are bonded in a bonding type, and the number of crimps is 25/25.
A non-woven fabric, which is composed of laminated composite short fibers having a crimp of mm or more, and the constituent fibers are partially heat-bonded to each other. 5. The core portion is made of a biodegradable thermoplastic polymer component having a high melting point, the sheath portion is made of a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer, and the number of crimps is 25/25 mm.
A non-woven fabric comprising the eccentric core-sheath type composite staple fibers having the above crimps, and the constituent fibers being three-dimensionally entangled. 6. A biodegradable thermoplastic polymer component having a high melting point and a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer are bonded to each other in a bonding type, and the number of crimps is 25/25.
A non-woven fabric comprising laminated composite short fibers having a crimp of not less than mm, wherein the constituent fibers are three-dimensionally entangled. 7. The biodegradable latent crimping property according to claim 1 or 2, wherein the biodegradable thermoplastic polymer is an aliphatic polyester polymer or an aliphatic polyesteramide copolymer. Composite staple fiber. 8. The nonwoven fabric according to claim 3, 4, 5, or 6, wherein the biodegradable thermoplastic polymer is an aliphatic polyester polymer or an aliphatic polyesteramide copolymer.