JPH0559611A - Highly strong polycaprolactone monofilament and its production - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having a high straight line tensile strength and a high knot strength. useful for industrial materials, etc., and having a biologically decomposing property by melt-spinning polycaprolactone having a specific melt flow rate, and subsequently subjecting the spun fiber to a multi- stage drawing process in a specific drawing ratio. CONSTITUTION:Polycaprolactone having a melt flow rate of <=10 is fed into an extruder type melt-spinning machine and melt-spun at a spinning temperature of 210 deg.C. The spun fiber is taken out at a rate of 10m/min, cooled in a water bath of 15 deg.C, immediately subjecting to the first step drawing treatment at a drawing ratio of 5-7 times in a 45 deg.C warm water, and subsequently subjecting to the second multi-stage drawing treatment at a total drawing ratio of >=8 times in a 100 deg.C oven to obtain the objective polycaprolactone monofilament having a straight line tensile strength of >=6.0g/d, a knot strength of >=4.0g/d, capable of being supplied for general industrial materials, and having a high strength and good biodecomposability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable high-strength polycaprolactone monofilament and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a monofilament for industrial materials used for fishing nets, fishing lines, agricultural nets, etc., those mainly composed of polyamide, polyester, vinylon, polyolefin and the like have been used. Therefore,
These monofilaments have no problem of self-degrading and cause various pollution when left in the sea or mountains after use. This problem can be solved by incineration, landfilling or recovery and recycling after use, but since such processing requires a large amount of money, it is actually left in the sea or mountains, and birds, marine life, divers, and so on. Often, there are situations such as being entangled with a car and killing it, or entangled with the screw of a ship and causing a ship accident.

As a method for solving such a problem, it is considered to use a material which is naturally decomposed or decomposed by light or microorganisms.

Polycaprolactone is a relatively inexpensive, fully biodegradable synthetic polymer, and it is well known that these are gradually degraded when placed in an environment in which microorganisms such as living organisms or soil live. ing. For example, Japanese Patent Laid-Open No. 1-17
No. 5855 proposes a surgical monofilament suture made of polycaprolactone, and describes the change over time in the residual tensile strength when the suture is embedded in the rabbit back muscle.

However, the linear tensile strength of the polycaprolactone monofilament disclosed in JP-A-1-175855 is at most 5.85 g / d, which is insufficient for use in fishing nets, fishing lines and other general industrial material applications. However, it was impossible to put it to practical use.

[0006]

DISCLOSURE OF THE INVENTION The present invention is to provide a biodegradable polycaprolactone monofilament which has high strength and can be used for fishing nets, fishing lines and other general industrial materials.

[0007]

The present invention is intended to solve the above-mentioned problems, and its gist is as follows. (1) A monofilament made of polycaprolactone having a linear tensile strength of 6.0 g / d or more and a knot strength of
High-strength polycaprolactone monofilament characterized by being 4.0 g / d or more. (2) When melt-spinning a polycaplacton having a melt roll rate of 10 or less and stretching it to produce a monofilament, the stretching ratio of the first stage is more than 5 times and less than 7 times,
A process for producing a high-strength polycaprolactone monofilament, which comprises multi-stage drawing such that the total draw ratio is 8 times or more. The melt flow rate referred to in the present invention is JIS K 6760.
The value is measured in accordance with, and the unit is g / 10 min.

The present invention will be described in detail below. The polycaprolactone used in the present invention has a melt flow rate of 10 or less, preferably 5 or less. Conventionally, it has been difficult to obtain such a high degree of polymerization of polycaprolactone in the market, but it has become available for the first time since it was recently put on the market by UCC, USA. In addition, it is also desirable to mix an aliphatic polyester or a polyolefin with the polycaprolactone within a range that does not impair the characteristics of the monofilament of the present invention.

The present invention succeeded in obtaining a polycaprolactone monofilament of extremely high strength which has never been known so far by melt spinning such a high degree of polymerization polycaprolactone and drawing it under appropriate drawing conditions. It is a thing.

In the present invention, first, polycaprolactone is melt-spun, and the spinning temperature is suitably 190 to 300 ° C, preferably 200 to 250 ° C. Spinning temperature is 190
If the temperature is lower than 0 ° C, melt extrusion is difficult, and if the temperature exceeds 300 ° C, the polymer is remarkably decomposed, so that it becomes difficult to obtain a high-strength monofilament. The spin take-up speed is 5 to 20 m / min, preferably 7 to 15 m / min.

The melt spun monofilament is 15-25
After cooling with water at ℃, it is stretched once or continuously without winding. Stretching is performed in multiple stages,
The first-stage stretching is performed at room temperature in hot air or heated water, a heating medium such as glycerin, ethylene glycol, or silicone oil. The first-stage stretching is usually performed at a temperature not higher than the melting point (60 ° C.) of polycaprolactone and a stretching ratio of more than 5 times and less than 7 times. When the draw ratio of the first stage is 5 times or less, uneven stretch occurs, while when it is 7 times or more, cutting frequently occurs, which is not preferable. Stretching from the second stage onwards
Although it may be carried out in the same manner as in the first step, it is usually carried out in a hot atmosphere at a temperature not lower than the melting point of polycaprolactone, preferably 80 to 120 ° C. In any case, in order to obtain a high-strength monofilament, it is necessary to draw it so that the total draw ratio is 8 times or more.

The thus stretched monofilament is heat-treated at a temperature of 60 to 120 ° C., if necessary. The fineness of the monofilament of the present invention is appropriately selected depending on the application, but is usually 50 d or more. The monofilament of the present invention has excellent high-strength characteristics and biodegradability as described above, which is suitable for industrial materials.

[0013]

EXAMPLES The present invention will be described in more detail below with reference to examples. The linear tensile strength and knot strength tests are JIS
It was measured according to L 1013. Further, the sample was buried in soil for 3 months and then taken out. When the monofilament lost its shape or the tensile strength retention rate was 50% or less, it was judged that the biodegradability was good.

Examples 1 to 10 and Comparative Examples 1 to 4 Polycaprolactone having a melt flow rate of 4.0 was supplied to an extruder type melt spinning machine, melt spun at a spinning temperature of 210 ° C., and taken out at a speed of 10 m / min. After cooling in a water bath at 15 ° C, immediately in a warm water bath at 45 ° C, the first stage drawing was performed at the draw ratio DR ₁ shown in Table 1, and then 100 ° C.
In an oven, subjected to total draw ratio DR _T become as second-stage stretching shown in Table 1, further, wound up relaxed heat-treated in 100 ° C. oven, monofilament diameter 0.25~0.40mm Got The characteristic values of the obtained monofilament are shown in Table 1.

[0015]

[Table 1]

[0016]

According to the present invention, a high-strength polycaprolactone monofilament that can be put to practical use as a general industrial material is provided. The polycaprolactone monofilament of the present invention is suitable for fishing materials such as fishing nets and fishing lines, insect repellents, agricultural materials such as bird-prevention nets and vegetation nets, and other general industrial materials. If it is left underneath, it will be completely decomposed after a certain period of time, so using the monofilament of the present invention does not require special waste treatment,
It is possible to prevent pollution.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location D01F 6/62 302 C 7199-3B E 7199-3B (72) Inventor Shuji Takahashi 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Stock Company Central Research Laboratory (72) Inventor Naoki Kanemoto 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Stock Company Central Research Center (72) Inventor Katsuhiko Hayashi 2-29-9 Shonan Takatori, Yokosuka City, Kanagawa Prefecture (72) ) Inventor Kunihiro Hirose 2-24-3-103 Kyomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa

Claims (2)

[Claims] 1. A monofilament made of polycaprolactone, having a linear tensile strength of 6.0 g / d or more,
A high strength polycaprolactone monofilament having a knot strength of 4.0 g / d or more. 2. When melt-spinning a polycaplacton having a melt roll rate of 10 or less and stretching it to produce a monofilament, the draw ratio of the first stage is more than 5 times and less than 7 times, and the total draw ratio is The method for producing a high-strength polycaprolactone monofilament is characterized in that multi-stage drawing is performed so that the ratio is 8 times or more.