JPH08144127A - Biodegradable conjugate monofilament - Google Patents

Abstract

PURPOSE: To obtain at a low cost the subject monofilament having a specified heat resistance, excellent in knot strength and wear resistance, and high in biodegradation rate. CONSTITUTION: This monofilament is a sheath/core type conjugate monofilament composed, for both sheath and core components, of a copolymer comprising polybutylene succinate (PBS) and polybutylene adlpate(PBA) or polybutylene sebacate(PBS) with the PBS component accounting for 70-100mol% of the final monofilament. For this monofilament, the PBS content of the copolymer for the sheath stands lower than that for the core. The other version of this monofilament is made up of a copolymer of PBS and polyethylene succinate(PES) as the core with the PBS content at 85-100mol% and a copolymer of PBS and PBA or PBSe as the sheath with the PBS content at 70-95mol%. For the latter monofilament, the PBS content of the copolymer for the sheath stands lower than that for the core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable composite monofilament which can be used as a fiber for industrial materials, has a certain heat resistance, is excellent in knot strength and abrasion resistance, and has a fast biodegradation rate. is there.

[0002]

2. Description of the Related Art Conventionally, as fibers for industrial materials, fibers excellent in yarn quality performance such as strength and weather resistance have been required,
Mainly polyamide, aromatic polyester, vinylon,
Those made of polyolefin or the like are used. However, there is a problem that these fibers are not degradable and cause various pollutions when left in a natural environment. This problem is solved by incineration, landfilling, recovery and recycling after use, but it is difficult at present because these processes require a great deal of expense and labor.

As one method for solving such a problem, it is possible to use a biodegradable polymer. However, the biodegradable polymer has a problem that it has a low melting point, is expensive, and the fiber strength is inferior as compared with a general-purpose polymer.

Therefore, the present inventors have previously proposed Japanese Patent Application No. 6-8.
No. 7305, polybutylene succino that is inexpensive and has a certain heat resistance that can be put to practical use, has excellent physical properties, especially knot strength and abrasion resistance, and that is completely decomposed by microorganisms in a natural environment. We proposed a biodegradable composite monofilament, which is a copolymer of nate and polyethylene succinate, in which the sheath part is composed of a polymer having a lower melting point than the core part. Although this biodegradable composite monofilament showed good physical properties, it has a problem that the rate of degradation is slower than that of fibers made of other biodegradable polymers, and its improvement has been desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention is inexpensive and has a certain degree of heat resistance that can be put to practical use, is excellent in knot strength and abrasion resistance, and is used under natural environment after use. The present invention is intended to provide a biodegradable composite monofilament having a high biodegradation rate, which is completely decomposed by microorganisms.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have conducted a suitable spinning of a core-sheath type composite monofilament in which a specific polybutylene succinate copolymer is combined, It has been found that this object can be achieved by spinning under drawing conditions, and the present invention has been achieved.

That is, the gist of the present invention is as follows.

(1) A copolymer of polybutylene succinate (PBS) and polybutylene adipate (PBA) or polybutylene sebacate (PBSe) for both the core and the sheath, wherein the PBS component is 70 to 100 mol. % Of the copolymer, the biodegradable composite monofilament characterized in that the ratio of the PBS component of the copolymer of the sheath part is smaller than that of the copolymer of the core part.

(2) The core is a copolymer of PBS and polyethylene succinate (PES), and the PBS component is 85
Consists of ~ 100 mol% copolymer with sheath of PBS and PB
A copolymer with A or PBSe, wherein the PBS component is 70
A core-sheath type composite monofilament composed of ˜95 mol% of the copolymer, wherein the proportion of the PBS component in the sheath copolymer is lower than that in the core copolymer. Composite monofilament.

Hereinafter, the present invention will be described in detail.

The polymer used in the present invention preferably has a number average molecular weight of about 30,000 or more from the viewpoints of spinnability and properties of the obtained yarn.

In the first invention, both the core portion and the sheath portion are made of PB.
It is composed of a copolymer of S and PBA or PBSe.

This copolymer has a PBS component ratio of 70-
It should be 100 mol%, preferably 80-100 mol%. If the proportion of the PBS component is less than 70 mol%, the resulting composite monofilament is inferior in linear strength and knot strength because the polymer is flexible and has low crystallinity.

Further, in the first invention, it is necessary to use, as the sheath copolymer, a copolymer in which the proportion of the PBS component is smaller than that of the core copolymer. When the proportion of the PBS component of the copolymer is small, the copolymer becomes softer and has lower crystallinity. By arranging this in the sheath portion, knot strength,
It becomes a monofilament having excellent abrasion resistance and biodegradability.

The difference in the proportion of the PBS component of the copolymer of the core portion and the sheath portion is suitably 10 to 20 mol%.

In the second invention, the core portion is made of PBS and PE.
It is composed of a copolymer of S and a sheath of PBS and PBA or PBSe.

The copolymer of the core has a ratio of PBS component of 85.
-100 to 100 mol%, preferably 90 to 100 mol%, and the sheath copolymer must have a PBS component ratio of 70 to 95 mol%, preferably 70 to 85 mol%. .
If these requirements are not satisfied, the linear strength and knot strength of the obtained composite monofilament will be poor.

Also in the second invention, it is necessary to use, as the sheath copolymer, a copolymer in which the proportion of the PBS component is smaller than that of the core copolymer. If the proportions of PBS components in the copolymer are the same, PBA or PB
Since the copolymer with Se has a softer property and higher biodegradability than the copolymer with PES, by adopting this constitution, as in the case of the first invention, knot strength and abrasion resistance are obtained. And a monofilament with excellent biodegradability.

The difference in the proportion of the PBS component of the copolymer of the core portion and the sheath portion is preferably 10 to 20 mol% as in the first invention.

The weight ratio of the core portion and the sheath portion constituting the monofilament is preferably 2/1 to 5/1. If the proportion of the core is smaller than this range, the linear strength and knot strength of the monofilament will decrease, and if it is large, the effect of the sheath will be small and no improvement in knot strength, wear resistance and biodegradability will be seen. .

To produce the monofilament of the present invention, the above-mentioned two kinds of copolymers are used and melt-spun from a composite nozzle consisting of two layers of concentric sheath cores.

The spinning temperature varies depending on the type of copolymer used, but is preferably 150 to 220 ° C. If the spinning temperature is less than 150 ° C, melt extrusion is difficult, and if it exceeds 220 ° C, thermal decomposition of the polymer becomes remarkable, and it becomes difficult to obtain a high-strength monofilament.

The melt-spun composite monofilament is
Depending on the copolymer used for the sheath portion, it is cooled in a cooling bath such as water or ethylene glycol within a temperature range of 10 ° C lower than the crystallization temperature to 40 ° C lower than the crystallization temperature. If the cooling temperature is higher than this range, deformation may occur on the yarn path changing roller or guide in the cooling bath due to insufficient cooling. Further, this type of copolymer has a slow crystallization rate, so that when the temperature is lower than the above temperature range, the crystallization does not proceed in reverse, and when a plurality of filaments are spun from the same spinneret, Adhesion between them may occur.

The cooled undrawn yarn is drawn once or continuously without being wound.

In order to obtain a high-strength composite monofilament, one-stage drawing is not sufficient, and multi-stage drawing is necessary. The first-stage stretching is carried out at room temperature, in hot air or in a heating medium such as heated water, glycerin, ethylene glycol, silicone oil or the like, at a temperature not higher than the melting point of the copolymer used, and a stretching ratio of 5 to 7 times. Done in. If the first stage draw ratio is less than 5 times, uneven stretch occurs, while if it exceeds 7 times, frequent cutting occurs, which is not preferable. Stretching in the second and subsequent stages may be performed in the same manner as in the first stage, but usually, depending on the heating time, in the vicinity of the melting point of the copolymer used,
It is preferably carried out in a hot atmosphere in the range of 15 ° C. below the melting point to 30 ° C. above the melting point. The total draw ratio is not particularly limited as long as it can be drawn with good drawability, but is usually about 7 to 8 times.

The composite monofilament of the present invention thus obtained is, as mentioned above, inexpensive and has a certain heat resistance sufficient for practical use and excellent physical properties and biodegradability.

[0027]

EXAMPLES Next, the present invention will be specifically described by way of examples. The method of measuring the characteristic value and the like are as follows. Melting point and crystallization temperature Determined by DSC measurement. Strength characteristics The measurement was performed according to JIS L 1013. Biodegradability A monofilament sample having a length of 10 m was skein-shaped, buried in soil for 3 months from July to October, taken out, weighed, and evaluated by a weight reduction rate. Abrasion resistance A monofilament sample with a length of 20 cm is loaded with a load of 0.2 g / d, a hexagon wrench with a diameter of 4.0 mm is used as a friction element, the number of strokes is 36 times / min, the stroke length is 72 mm, and the friction angle is 90.
The friction test was conducted under the condition of the degree, and the number of times until the monofilament was cut was measured and evaluated.

Example 1 The number average molecular weight was about 40,000 and the proportion of PBS component was 80 mol%.
And a copolymer of PBS and PBA having a number average molecular weight of about
At 40,000, the PBS component ratio is 100 mol% PBS are separately supplied to an extruder type melt spinning machine, melted at a spinning temperature of 160 ° C, and the diameter of the sheath core is 2.1 mm so that the weight ratio becomes 1/3. After being spun from a spinneret having two spinning holes, it was cooled in a water bath with a length of 2 m and a temperature of 16 ° C, then taken up by a take-up roller, and immediately drawn in a warm water bath of 65 ° C with a draw ratio (DR1) of 5.2 times. At the first stage, and then
The total draw ratio (TD
(R) is stretched in the second step so that it becomes 7.9 times, and further, after relaxation heat treatment of 0.95 times in an oven with a length of 1.5 m and a temperature of 125 ° C, it is wound and a composite with a diameter of 0.286 mm. A monofilament was obtained.

Examples 2 to 4 When a composite monofilament was obtained by the same method as in Example 1, yarn was produced under the conditions shown in Table 1.

Comparative Examples 1 to 5 When a composite monofilament or a single-component monofilament was obtained by the same method as in Example 1, spinning was performed under the conditions shown in Table 1.

Table 1 shows the spinning conditions and the characteristic values of the obtained monofilaments in the above Examples and Comparative Examples.

[0032]

[Table 1]

As is clear from Table 1, in Examples 1 to 4 of the present invention, monofilaments having high linear strength and knot strength and excellent biodegradability were obtained. However, in Comparative Examples 1 to 3 which are single-component monofilaments, only monofilaments having a high linear strength but poor knot strength, abrasion resistance or biodegradation rate were obtained. Further, in Comparative Examples 4 to 5 in which the ratio of the PBS component of the copolymer of the core part and the sheath part was reversed, only monofilaments having inferior properties were obtained.

[0034]

Industrial Applicability According to the present invention, there is provided a biodegradable composite monofilament which has a certain heat resistance and can be practically used as a general industrial material, and has excellent knot strength and abrasion resistance.

The biodegradable monofilament of the present invention is used for fishing materials such as fishing nets and fishing lines, agricultural materials such as insect repellent nets and vegetation nets, living materials such as composting bags, and other general industrial materials. Suitable,
After use, if left in an environment where microorganisms are present, it will completely decompose after a certain period of time, so using the composite monofilament of the present invention will prevent pollution without requiring special waste treatment. It becomes possible to do.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shuji Takahashi 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A core / sheath copolymer of polybutylene succinate and polybutylene adipate or polybutylene sebacate, wherein the polybutylene succinate component is 70 to 100 mol% of the copolymer. A core-sheath type composite monofilament, wherein the proportion of polybutylene succinate in the copolymer of the sheath portion is lower than that of the copolymer of the core portion. 2. The core is a copolymer of polybutylene succinate and polyethylene succinate, the polybutylene succinate component is 85 to 100 mol% of the copolymer, and the sheath is a polybutylene succinate. A polybutylene adipate or polybutylene sebacate copolymer, wherein the polybutylene succinate component is 70 to 95 mol%
Is a core-sheath type composite monofilament, wherein the proportion of polybutylene succinate in the copolymer of the sheath is smaller than that of the copolymer of the core. .