JPH06212511A - Biodegradable staple fiber - Google Patents

Abstract

PURPOSE:To obtain a biodegradable staple fiber having >=100 deg.C heat resistance and excellent crimp characteristics and strength. CONSTITUTION:This staple fiber is composed of a biodegradable thermoplastic polymer having >=100 deg.C melting point and has >=2.0g/d tensile strength, <=100% breaking elongation, 8-35 peaks/25mm number of crimps and >=5.0% crimp ratio.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biodegradable staple-made of a biodegradable thermoplastic polymer having a melting point of 100 ° C. or higher.
It's about fiber.

[0002]

2. Description of the Related Art Conventionally, synthetic fibers such as polyolefins, polyamides, polyesters, and vinylon have been mainly used as economical fibers for living materials such as sanitary materials such as diapers and sanitary napkins, disposable towels and wiping cloths. Has been done. However, these fibers are not self-decomposable, and there is a problem that they cause various kinds of pollution when left outdoors after use. Therefore, these living materials are inevitably incinerated at present.

As a method for solving such a problem, it is possible to use a biodegradable material.

Conventionally, as biodegradable polymers, polysaccharides such as cellulose and chitin, proteins and polypeptides (polyamino acids) such as cut gut (intestinal line) and regenerated collagen, and poly-3-hydroxybutyrate produced by microorganisms in the natural world. Microbial polyesters (poly-β-hydroxyalkanoates) such as phthalates or copolymers thereof, poly (α-oxy acids) such as polyglycolide and polylactides, poly-ω-hydroxy such as polycaprolactone and polypropiolactone. Synthetic aliphatic polyesters composed of a dicarboxylic acid component and a glycol component such as alkanoate, polyethylene succinate and polybutylene succinate are well known.

Among these, it is known that cotton, which is natural cellulose, and rayon, which is regenerated cellulose, are relatively inexpensive biodegradable materials. However, these cellulosic materials generally have poor mechanical strength under wet conditions. Further, since these cellulosic materials are hydrophilic, they can be used for applications where hydrophobicity is required, for example, for napkin cover stock (surface sheet) where polyolefin short fiber nonwoven fabric is currently used. Can not. Further, since it is not thermoplastic, it cannot be used as a heat fusion fiber.

Further, when fibers are produced from chitin or polypeptide, they must be produced by a wet spinning method, or the production cost is high due to the extremely high cost of raw materials, and high strength fibers can be obtained. There was a problem that it could not be done.

Among them, polycaprolactone is a relatively inexpensive, completely biodegradable synthetic polymer which can be melt-spun, and actually produces short fibers having a certain strength and crimping property. However, polycaprolactone has a melting point of about 60 ° C.
60 ° C during its processing or use due to its low temperature
There is a problem that it cannot be used when exposed to the above atmosphere.

[0008]

DISCLOSURE OF THE INVENTION The present invention is relatively inexpensive, has heat resistance of 100 ° C. or higher, has excellent crimping properties and strength that can be put to practical use, and is completely decomposed by microorganisms. The present invention seeks to provide biodegradable staple fibers.

[0009]

The present invention is to solve the above problems and provides a staple fiber made of a biodegradable thermoplastic polymer having a melting point of 100 ° C. or more and having a tensile strength of 2.0 g / d or more, crimp number 8 to 35/25
The gist is a biodegradable staple fiber characterized by having a mm, a crimping degree of 5.0% or more, and a cutting elongation of 100% or less. The staple fiber of the present invention also includes a mixture of a small amount of a plasticizer, a crystal nucleating agent, a low melting point biodegradable polymer, etc. within a range satisfying the above characteristics.

The present invention will be described in detail below. The biodegradable thermoplastic polymer having a melting point of 100 ° C. or higher used in the present invention has a melt flow rate (g / 10 min) measured according to JIS K 6760 of 30 or less, preferably 10 or less. When the melt flow rate exceeds 30, it is difficult to obtain the staple fiber having the strength and the crimping property which are the objects of the present invention.

The biodegradable thermoplastic polymer of the present invention has a melting point of 100 ° C. or higher, preferably 120 ° C. or higher. Specific examples include poly-3-hydroxypropionate and poly-3-hydroxybutyrate. Rate, poly-3-
Hydroxycaprolate, poly-3-hydroxyheptanoate, poly-3-hydroxyoctanoe and their copolymers (for example, poly-3-hydroxybutyrate and poly-4-hydroxybutyrate Union),
Examples thereof include poly-γ-butyrolactone, polyethylene succinate, polybutylene succinate, polyneopentyl succinate, polyneopentyl oxalate, polyglycolide, polylactide, and copolymers and blends thereof.

The staple fiber of the present invention can be produced by melt spinning the above-mentioned biodegradable thermoplastic polymer, stretching it, mechanically crimping it, and cutting it.

The temperature of melt spinning varies depending on the type of the biodegradable thermoplastic polymer used and the melt flow rate, but is preferably 180 to 300 ° C. Spinning temperature is 1
If it is less than 80 ° C, melt extrusion is difficult, and if it exceeds 300 ° C, decomposition becomes remarkable, and it becomes difficult to obtain high-strength staple fibers having excellent crimping properties.

The melt spun yarn is quenched below the crystallization temperature. In this case, the melting point of the biodegradable polymer is generally low, and therefore the crystallization temperature is in the range of about 60-105 ° C, which is sufficient to promote a certain oriented crystallization in the draft process from nozzle to take-off roller. If not cooled, the resulting yarn will have poor mechanical strength and crimp characteristics. The cooled yarn is stretched in one step or two or more steps, once or without being wound, at room temperature to 110 ° C. The draw ratio is 2.0 g / d depending on the spinning speed and the required performance of the desired staple fiber.
It is set so that a fiber having the above tensile strength and a breaking elongation of 100% or less can be obtained. If the tensile strength is less than 2.0 g / d, it is not preferable because troubles may occur in the working process or troubles may occur in practice due to insufficient strength of the final product. On the other hand, if the cutting elongation exceeds 100%, the crimping property, particularly the crimping rate, becomes poor, and it becomes difficult to put it into practical use.

Next, the drawn yarn is crimped to 8 to 35 co / 25 mm, preferably 10 to 30 co / 25 mm by a stuffing box method, an indentation heating gear method, a high speed air jet indentation method or the like, and 20 to 20 Cut to a length of 100 mm. In this case, if the number of crimps is less than 8/25 mm, unopened portions are likely to occur in the carding process, and if it exceeds 35/25 mm, nep is likely to occur. In addition, it is necessary to set the crimping degree to be 5.0% or more. If the crimping degree is less than 5.0%, the web is likely to have density unevenness due to poor conjugation when applied to a card in the next step. . When crimping is applied by the indentation heating gear method, the yarn before entering the crimper is preheated to 40 to 80 ° C in a hot water bath or the like, then the nip pressure is 1.0 to 3.5 kg / cm ² , and the indentation pressure is 1.0 to
Pass it through a 3.5 kg / cm ² crimper, apply oil and dry it, and finally cut into staple fibers with a cutter. In this case, the number of crimps and the degree of crimp can be increased by increasing the packing density of the yarns that enter the crimper.

The staple fiber of the present invention thus obtained has a heat resistance of 100 ° C. or higher and, as described above, has excellent crimping property, strong elongation property and biodegradability. . The single fiber fineness of the staple fiber is usually 1 to 20d.

The staple fiber of the present invention is processed into a spun yarn and a plain knitted fabric by a conventionally known spinning process, or is used as a short fiber nonwoven fabric through a dry or wet process.

[0018]

EXAMPLES Next, the present invention will be specifically described by way of examples. The tensile strength and elongation properties were measured according to JIS L 1015. Further, the sample was buried in soil for 2 months and taken out, and it was judged that the biodegradability was good when the staple fiber lost its shape.

Example 1 Polyethylene succinate having a melting point of 102 ° C. and a melt flow rate of 5 was used at a spinning temperature of 230 ° C. and 30 spinning holes having a diameter of 0.3 mm.
Melt spinning at a spinning speed of 1000 m / min from the spinneret that has
After cooling by blowing air at 5 ° C., the undrawn yarn was wound up. This unstretched yarn was drawn 2.8 times at 60 ° C, then preheated in a warm water bath at 60 ° C, and a pushing gear type crimper (nip pressure: 3.0 kg / cm ² , pushing pressure: 3.0 kg / cm ² ) And crimping it, and then applying an oil agent and drying it to a length of about 51
A staple fiber having a fineness of 3d was obtained by cutting it into mm. The resulting staple fiber has a tensile strength of 3.2.
g / d, cutting elongation 56.4%, number of crimps 18.6 / 25 mm, crimp degree
The biodegradability was good at 12.8%.

Example 2 Poly-L-lactic acid having a melting point of 178 ° C. and a melt flow rate of 8 was melt-spun at a spinning temperature of 190 ° C. from a spinneret having 24 spinning holes of 0.3 mm in diameter at a spinning speed of 600 m / min, After cooling by blowing air at 8 ° C, the undrawn yarn was wound up. The undrawn yarn was drawn 4.2 times at 90 ° C., then preheated in a hot water bath at 80 ° C. and treated in the same manner as in Example 1 to obtain a staple fiber having a fineness of 3 denier. The obtained staple fiber has a tensile strength of 2.8 g / d and a breaking elongation of 3
The biodegradability was good with 8.1%, crimp number 16.1 pcs / 25 mm, and crimp degree 13.2%.

[0021]

EFFECTS OF THE INVENTION According to the present invention, the heat-resistant temperature is 80 ° C. or higher, and it has excellent crimp characteristics and strength characteristics that can be practically used.
And biodegradable staples that are hydrophobic and have heat fusion properties
Fiber is provided. The knitted woven fabric or nonwoven fabric using the staple fiber of the present invention can be used as a cover stock (surface sheet) such as disposable diapers and sanitary napkins, sanitary materials such as disposable hand towels and pads, and a living cloth such as wiping cloth and a base fabric for a patch. It is suitable as a material, and if left in an environment (soil or water) where microorganisms are present after use, it will be completely biodegraded after a certain period of time, so no special waste treatment is required and pollution prevention It is useful. In addition, by composting, it can be reused as fertilizer.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location D01G 1/00 A 7152-3B D02G 3/02 ZAB 3/24 ZAB (72) Inventor Naoki Kanemoto Uji Kyoto Prefecture 23 Ujikozakura, Ushi, Japan Centralika Research Institute, Central Research Institute

Claims (1)

[Claims] 1. A staple fiber comprising a biodegradable thermoplastic polymer having a melting point of 100 ° C. or higher, having a tensile strength of 2.0 g / d or more, a crimp number of 8 to 35 co / 25 mm, and a cutting elongation. Biodegradable staple fiber characterized by 100% or less and crimping degree of 5.0% or more.