JPH06207320A - Biodegradable conjugate short fiber and its nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain biodegradable conjugate short fibers having biodegradability, excellent mechanical strength and dimensional stability, improved thermal adhesion, capable of providing nonwoven fabric useful as a material for sanitary material and a material related to life. CONSTITUTION:Biodegradable conjugate short fibers comprises a core part composed of a high-melting biodegradable thermoplastic polymer component and a sheath part composed of a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer. Nonwoven fabric is made of the biodegradable conjugate short fibers comprising a core part composed of a high-melting biodegradable thermoplastic polymer component and a sheath part composed of a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer wherein the constituent fibers are partially thermally bonded mutually or interlaced in a three- dimensional way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite staple fiber suitable for obtaining a non-woven fabric having biodegradability, excellent mechanical strength and dimensional stability, rich flexibility, and thermal adhesion. It relates to the non-woven fabric.

[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]

DISCLOSURE OF THE INVENTION The present invention solves the above problems, and obtains a non-woven fabric having biodegradability, excellent mechanical strength and dimensional stability, rich flexibility, and thermal adhesiveness. The present invention is intended to provide a composite staple fiber and a nonwoven fabric thereof suitable for use in

[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 a biodegradable composite staple fiber having a core made of a high-melting biodegradable thermoplastic polymer component and a sheath made of a biodegradable thermoplastic polymer component having a lower melting point than the polymer. It is a summary. The present invention also provides a biodegradable 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. The gist of the present invention is a non-woven fabric characterized in that the constituent fibers are partially heat-bonded to each other. Furthermore, the present invention provides a biodegradable 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 melting point lower than that of the polymer. The gist is a non-woven fabric which is characterized in that the constituent fibers are three-dimensionally entangled with each other.

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 As described above, they are joined so as to have a concentric core-sheath type composite form in which the both polymer components are arranged. In this composite short fiber, a non-woven polymer is produced when a nonwoven web is prepared by using the fiber obtained when the difference in melting point between the two polymer components is less than 3 ° C. and heat-treated to form a nonwoven fabric. Not only the component but also the high melting point polymer component softens and melts, which is not preferable. Therefore, in the present invention, the melting point difference is 3 ° C. or more, preferably 5 ° C. or more, more preferably 10 ° C. or more.
℃ or above. 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 a thermoplastic polymer component having a biodegradability of the sheath has a melting point of 60 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher, short fibers having this sheath are used. When a non-woven fabric is prepared by using, the non-woven fabric can have a certain heat resistance, which is preferable. In this composite short fiber, the composite ratio, that is, the weight ratio of the polymer component in the sheath to the polymer component in the core is preferably 1/5 to 5/1. When the ratio of the polymer component in the core portion to the polymer component in the sheath portion exceeds 5, the strength of the short fibers decreases, or the nonwoven fabric obtained by using the short fibers becomes hard and the texture deteriorates. Therefore, on the other hand, when the ratio of the polymer component of the core portion to the polymer component of the core portion is less than 1, the nonwoven fabric obtained by thermally bonding the fibers using the short fiber is a constituent fiber. Any of them is not preferable because the strength is lowered in the heat-bonded portion between them. Therefore, in the present invention, the composite ratio is 1/5 to 5/1, preferably 1/2 to 2/1.

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. On the other hand, when the single fiber fineness exceeds 20 denier, the nonwoven fabric obtained by using the short fibers has a rough and rough texture and is inferior in quality.

The nonwoven fabric of the present invention is composed of the above-mentioned composite short fibers, and the constituent fibers are partially heat-bonded to each other. Further, the nonwoven fabric is composed of the above-mentioned composite short fibers and the constituent fibers are tertiary. It is originally entangled. This partial thermal bonding is formed by a known thermal bonding process, and the three-dimensional entanglement is formed by a known so-called high pressure liquid flow process. Alternatively, the shape of the nonwoven fabric is maintained by three-dimensional entanglement, and the nonwoven fabric exhibits excellent mechanical strength and dimensional stability.

The nonwoven fabric made of the above-mentioned composite short fibers in the present invention preferably has a basis weight of 20 g / m ² or more. This non-woven fabric has a basis weight of 20 g / m
^If it is less than ² , the handling property is poor at the time of manufacturing the nonwoven fabric,
Particularly, when the basis weight is less than 10 g / m ² , the strength of the non-woven fabric itself is low, the texture of the non-woven fabric is rough and the quality thereof is inferior, or the productivity at the time of producing the non-woven fabric is decreased, which is not preferable.

The short fibers in the present invention can be efficiently produced by the following method. That is,
By 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-composite-spun and the spun yarn is cooled with air. After being cooled with running water or cooling water, it is once wound into an unstretched long fiber yarn, or continuously without being wound once, and subjected to cold stretching or hot stretching in one or more stages to obtain It can be obtained by, for example, applying a predetermined mechanical crimp to the drawn long-fiber yarn by using a stuffing box, or applying a predetermined crimp by heat shrinkage treatment, and then cutting it into a predetermined length. . The spinning temperature at the time of melt spinning depends on the melting point and the degree of polymerization of the polymer to be used, but is usually preferably 120 to 300 ° C. If the spinning temperature is less than 120 ° C, it will be difficult to melt-extrude the polymer, while if the spinning temperature exceeds 300 ° C, the thermal decomposition of the polymer will be so remarkable that high strength fiber cannot be obtained. Not preferable. The total draw ratio for drawing the undrawn long-fiber yarn depends on the strength level of the target short fiber, but is usually 2.0 to 4.0 times, and the total draw ratio is 3.0 g / denier or more. Short fibers having strength 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 produce a card web, and the resulting card web is heat-bonded to partially bond the constituent fibers to each other.
Alternatively, it can be obtained by subjecting the obtained card web to a high-pressure liquid flow treatment so that the constituent fibers are three-dimensionally entangled.

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. Further, the roller temperature is usually set to a temperature about 5 to 50 ° C. lower than the melting point of the low melting point thermoplastic polymer forming the sheath portion. By appropriately selecting this temperature, the adhesive force between fibers can be improved. It is possible to obtain a non-woven fabric that is high, that is, excellent in mechanical strength and dimensional stability, and 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 at the crossing points of the fibers using a hot air dryer, the treatment temperature depends on the treatment time,
Usually, it is preferable to set the temperature within the range of not less than the melting point of the low melting point thermoplastic polymer constituting the sheath and about 10 ° C. lower than the melting point of the high melting point thermoplastic polymer. In addition, these,
For example, the partial heat-bonding treatment using a hot embossing roller, a hot air dryer or an ultrasonic fusing device may be either 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.

[0014]

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).

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 of 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 a concentric core-sheath type at a temperature of 30 ° C. and a compounding ratio (weight ratio) of 1/1, cooling the spun yarn using a cooling air flow having a temperature of 20 ° C., and then applying an oil agent, 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 to 17 pieces / 2.
Apply 5mm mechanical crimp, cut into 51mm length,
A concentric core-sheath type composite short fiber cotton having a single fiber fineness of 2.0 denier was obtained. The obtained composite short fiber has a tensile strength of 4.1 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 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 heated at a temperature of Is 100
The fibers were partially heat-bonded to each other by passing them between an embossing roll heated to ℃ and a pressing area ratio of 15% and a smooth roll at the same temperature to obtain a nonwoven fabric. The resulting nonwoven fabric is KGSM
Tensile strength is 10.8kg / 5cm in the longitudinal direction and 6.9 in the lateral direction.
The mechanical strength and dimensional stability were excellent at kg / 5 cm. 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 3 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 is used, and the water pressure is 60 kg.
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 using a mangle roll, the web was dried at a temperature of 70 ° C. using a hot air dryer to obtain a nonwoven fabric. The resulting nonwoven fabric has a KGSM tensile strength of 1 in the machine direction.
It was 2.0 kg / 5 cm and transversely 8.1 kg / 5 cm, and was excellent in mechanical strength and dimensional stability, and was also highly flexible. 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.

[0018]

The biodegradable composite staple fiber of the present invention comprises a biodegradable thermoplastic polymer component having a high melting point in the core portion and a melting point lower than that of the polymer in the sheath portion. It is composed of a coalescing component and is suitable for obtaining a nonwoven fabric having biodegradability, excellent mechanical strength and dimensional stability, rich flexibility, and excellent 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 (72) Inventor Koji Inagaki 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Research Institute

Claims (5)

[Claims] 1. A biodegradable composite staple fiber comprising a core portion made of a biodegradable thermoplastic polymer component having a high melting point and a sheath portion made of a biodegradable thermoplastic polymer component having a melting point lower than that of the polymer. 2. A biodegradable composite staple fiber whose core comprises a high melting point biodegradable thermoplastic polymer component and whose sheath comprises a biodegradable thermoplastic polymer component having a lower melting point than said polymer. And the constituent fibers are partially heat-bonded to each other. 3. A biodegradable composite staple fiber whose core comprises a high melting point biodegradable thermoplastic polymer component and whose sheath comprises a biodegradable thermoplastic polymer component having a lower melting point than said polymer. And the constituent fibers are three-dimensionally entangled with each other. 4. The biodegradable composite staple fiber according to claim 1, wherein the biodegradable thermoplastic polymer is an aliphatic polyester polymer or an aliphatic polyesteramide copolymer. 5. The nonwoven fabric according to claim 2 or 3, wherein the biodegradable thermoplastic polymer is an aliphatic polyester polymer or an aliphatic polyesteramide copolymer.