JPH0559612A - Multifilament capable of being decomposed by microorganism - Google Patents

Abstract

PURPOSE:To provide the subject relatively inexpensive multifilaments comprising polycaprolactone, having a tensile strength of >= a specified value and a tensile breakage elongation of >= a specified value, having a strength permissible to be supplied for practical uses and capable of being perfectly decomposed by microorganisms. CONSTITUTION:The multifilaments comprising polycaprolactone and having a tensile strength of >=4.0g/d and a tensile breakage elongation of >=30%. The objective multifilaments are obtained by melt-spinning the polycaprolactone having a high polymerization degree and drawing the spun filaments. In order to maintain the tensile strength of >=14.0g/d and the tensile breakage elongation of >=30%, it is necessary to draw the filaments into a length of 2.6-3.2 times.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biodegradable multifilament composed of polycaprolactone.

[0002]

2. Description of the Related Art Conventionally, fibers having excellent strength and weather resistance are required as fibers for industrial materials used for fishing, agriculture, and civil engineering, and those mainly composed of polyamide, polyester, vinylon, polyolefin and the like are required. It is used. However, these fibers are not self-degradable, and there is a problem in that they cause various pollution when left in the sea or mountains after use. This problem can be solved by treating it by incineration, landfill or recovery after use, but since such treatment requires a large amount of money, it is actually left in the sea or mountains, which not only damages the landscape. In many cases, birds, marine life, and divers are entangled and killed, or entangled with the screw of a ship and causing a ship accident.

As a method for solving such a problem, it is conceivable to use a material which is naturally degradable (biodegradable or biodegradable).

Conventionally, as naturally degradable 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 nature. Microbial polyesters, such as rate or its copolymers,
Synthetic aliphatic polyesters such as polyglycolide, polylactide and polycaprolactone are well known.

However, when fibers are produced from these polymers, they must be produced by a wet spinning method, and the cost of the raw materials is extremely high, so that the production cost is high and the fibers having high strength are obtained. There was a problem that it could not be done.

For example, polycaprolactone is a relatively inexpensive, completely biodegradable synthetic polymer and can be melt-spun, but conventionally, the multifilament obtained from this has low strength and cannot be put to practical use. .. There are two reasons for this, one is that polycaprolactone with a high degree of polymerization has not been obtained in the past, and the other is that the melting point of polycaprolactone is as low as 60 ° C. It is believed that it was extremely difficult and was not established.

As an inexpensive material which is naturally disintegratable, polyethylene is mixed with starch, and a film formed by blending linear low-density polyethylene with about 6% starch is used as a shopping bag. Some have been put to practical use.

However, even if fibers are produced from polyethylene mixed with such a starch, the mechanical properties such as strength are remarkably inferior and cannot be used for industrial materials requiring high strength.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is intended to provide a multifilament composed of polycaprolactone which is relatively inexpensive and has a strength for practical use, and which is completely decomposed by microorganisms. It is a thing.

[0010]

Means for Solving the Problems The present invention is to solve the above problems, and the gist thereof is a multifilament made of polycaprolactone, which has a tensile strength of 4.
The biodegradable multifilament has a tensile elongation at break of 0 g / d or more and 30% or more.

The present invention will be described in detail below. Polycaprolactone used in the present invention is JIS K
Melt flow rate measured according to 6760 (g / 10min)
Is less than 25, preferably less than 10. Conventionally, it was difficult to obtain such polycaprolactone having a high degree of polymerization in the market, but it was made possible only when it was recently put on the market by UCC, USA.
When the melt flow rate exceeds 25, it is difficult to obtain a multifilament having a tensile strength of 4.0 g / d or more, which is the object of the present invention.

The multifilament of the present invention can be produced by melt-spinning polycaprolactone having a high degree of polymerization and stretching.

The temperature of melt spinning varies depending on the melt flow rate of the polycaprolactone used, but it is 200 to 280 ° C.
Is desirable. If the spinning temperature is less than 200 ° C, melt extrusion is difficult, and if it exceeds 280 ° C, the decomposition of polycaprolactone becomes remarkable and it becomes difficult to obtain high-strength multifilaments.

The melt-spun multifilament is air-cooled, usually wound up once, and then subjected to one or more stages of cold drawing. The total draw ratio varies depending on the required performance of the target multifilament, but in order to maintain a tensile strength of 4.0 g / d or more and a tensile elongation at break of 30% or more, 2.6-
It is necessary to draw 3.2 times.

The thus-obtained maltofilament of the present invention has excellent strength and elongation characteristics and microbial degradability that can be practically used as described above.

[0016]

EXAMPLES Next, the present invention will be described more specifically by way of examples. The tensile strength / elongation property was measured according to JIS L 1013. Further, the sample was buried in soil for one month and then taken out. When the multifilament lost its shape or the tensile strength retention rate was 50% or less, it was judged that the biodegradability was good.

Examples 1 to 4 and Comparative Example 1 Polycaprolactone having a melt flow rate of 30 and 4 was blended as it was or appropriately, and was preliminarily mixed with a twin-screw extruder so as to obtain the melt flow rate shown in Table 1. After melt-kneading, the chips were used and melt-spun at a temperature shown in Table 1 from a spinneret of 0.5 mmφ × 24 holes. After unwinding the undrawn yarn, it was cold-drawn about 3 times to obtain a 75d / 24f multifilament. Table 1 shows the tensile strength / elongation characteristics of the obtained multifilaments and the evaluation results of microbial degradability.

[0018]

[Table 1]

[0019]

EFFECTS OF THE INVENTION According to the present invention, a multifilament having a strength and elongation characteristic that can be practically used and biodegradable is provided. The multifilament of the present invention is suitable as a fishery material, an agricultural material, a civil engineering material, a sanitary material, a waste treatment material, etc., and should be left in an environment (soil or water) where microorganisms are present after use. For example, since it is completely biodegraded after a certain period of time, no special waste treatment is required and it is useful for preventing pollution.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Takahashi 23 Uji Kozakura, Uji City, Kyoto Prefecture Central Research Institute of the Unitika Co., Ltd. Inside the laboratory (72) Inventor Katsuhiko Hayashi 2-29-9 Shonan Takatori, Yokosuka City, Kanagawa Prefecture (72) Kunihiro Hirose 2-24-3-103 Kyomachi, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture

Claims (1)

[Claims] 1. A biodegradable multifilament comprising polycaprolactone, which has a tensile strength of 4.0 g / d or more and a tensile elongation at break of 30% or more.