JPH03249208A - Bio-degradable fiber - Google Patents

Abstract

PURPOSE:To provide a novel fiber composed of starch and a PVA polymer and usable as rope, string, fishing line, fishing net, etc., which is decomposed by organisms when left outdoors to prevent the environmental pollution. CONSTITUTION:The objective fiber is composed of starch and a PVA polymer and has a fiber strength of preferably >=3g/d.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention uses biodegradable fibers, especially ropes, strings, fishing nets, etc., which biodegrade over time when abandoned outdoors. This invention relates to new fibers that do not cause environmental pollution.

[Prior Art] Today, environmental pollution caused by waste has become a serious problem. There are many types of waste, including cans, bottles, plastic moldings, films, fishing nets, fishing nets, and ropes. In particular, synthetic fiber products such as ropes, strings, fishing nets, etc., if abandoned on the beach or in the ocean after use, not only spoil the beauty of the area, but also cause entanglement with small birds, marine life, and people diving. New problems were occurring, such as getting tangled in the ship's propeller.

These traditional synthetic fiber products are durable and do not degrade over many years. This has spread environmental pollution and made the problem even more serious. In order to solve these problems, it is necessary to develop biodegradable fibers that naturally disintegrate after a certain period of use and become harmless in terms of environmental pollution. The development of new fibers has become an issue that should be solved at an early stage in this technical field.

By the way, as for mixed spinning of starches and fiber-forming polymers, for example, Japanese Patent Publication No. 18353/1983 discloses wet spinning of an alkaline solution of a mixture of cellulose and starch. However, the fibers obtained by this method are intended to impart even more water absorption to cellulose fibers, and have a tensile strength of only about 2 g/d at most. It was unsuitable for industrial uses such as fishing nets and fishing nets.

[Problems to be Solved by the Invention] An object of the present invention is to provide a new fiber that naturally disintegrates after a certain period of time after use of the textile product and becomes harmless in terms of environmental pollution. Another problem is that as fibers for textile materials such as ropes, strings, strings, and fishing nets,
The object of the present invention is to provide biodegradable fibers that are harmless in terms of environmental pollution.

[Means for Solving the Problems] The above problems of the present invention can be solved by a biodegradable fiber made of starch and a polyvinyl alcohol polymer (hereinafter abbreviated as PVA polymer).

That is, in the biodegradable fiber of the present invention, the PVA-based polymer is a highly saponified PVA-based polymer having a saponification degree of preferably 98 mol% or more, more preferably 99.0 mol% or more. Further, the degree of polymerization of the PVA-based polymer is preferably 1000 or more, more preferably 1500 or more. If the degree of polymerization is less than 1,000, it becomes difficult to obtain sufficient strength properties as, for example, industrial material fibers.

Furthermore, if necessary, a PVA-based polymer copolymerized with ethylene or the like can be used to improve water resistance.

The composition of starch, such as amylose and amylopectin, differs depending on the raw material, but examples include potato starch, corn starch, wheat starch, tapioca, and waxy maize.

The mixing ratio of the PVA-based polymer and starch is such that the amount of starch is preferably 15% to 70% by weight, more preferably 20% to 6% by weight based on the total fibers. The amount of starch may be appropriately determined in relation to the desired biodegradation period, but when the amount is within this range, biodegradation is likely to occur and fibers with sufficiently high strength properties are likely to be obtained.

Furthermore, the fiber of the present invention made of the PVA-based polymer and starch has a tensile strength of preferably 3 g/d or more, more preferably 4 g/d or more, and preferably 5 g/a or more. If the tensile strength does not reach 3 g/d, the fiber may be insufficient in strength, for example, as a fiber for industrial materials.

The fibers of the present invention contain organic peroxides such as benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, and j-butyl peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate to promote biodegradation. A small amount of an inorganic oxidizing agent such as, a photosensitizer such as benzophenone, a metal complex, an aromatic ketone, or a photodegradable polymer compound whose main component is vinyl ketone can be added. In order to impart water resistance to the fibers of the present invention, it is also a preferred technique to graft-polymerize a portion of the starch with polyacrylonitrile, polyvinyl acetate, polystyrene, or the like.

Next, an example of manufacturing the fiber of the present invention will be explained.

The fiber of the present invention is made by combining the PVA-based polymer and starch with water or an organic solvent such as dimethyl sulfoxide (hereinafter referred to as DMSO).
A spinning dope dissolved in (abbreviated as) can be obtained by dry spinning, wet spinning, dry-wet spinning, gel spinning, etc. Among these, the dry-wet spinning method is preferable because it facilitates obtaining a fine fiber structure.

Here, a method for producing the fiber of the present invention using a dry-wet spinning method, which is a particularly preferred spinning method, will be explained.

First, starch (for example, corn starch) and PVA-based polymer (saponification degree of 99.5 mol% or more, polymerization degree of 1000
or more), preferably in a weight ratio of 15/85 to 70/3
A spinning stock solution is prepared by dispersing it in DMSO so that it has a concentration of 0.0 and dissolving it by heating. At this time, the spinning stock solution has a hydrogen ion concentration (
PH) is set in the range of 5 to 8, and a small amount of oxalic acid or the like is usually added to adjust it to this value. If the pH is 5 or less, the ether bonds in starch are likely to be decomposed and broken, and if the pH is 8 or more, the spinning stock solution tends to be significantly colored.

Here, the polymer concentration (PVA-based polymer and starch equivalent) in DMSO is preferably 5 to 50% by weight, more preferably 10 to 40% by weight.

Of course, the polymer concentration varies depending on the blend ratio of PVA and starch, the degree of polymerization of the PVA-based polymer used, etc.;
It is desirable to adjust the temperature to a poise (a t 100'C).

The spinning dope thus obtained is subjected to dry-wet spinning.

That is, the yarn discharged from the spinneret is once introduced into a coagulation bath of methanol, ethanol, etc. through an air atmosphere and coagulated. After removing the solvent, the coagulated yarn is cold-stretched using double rollers, and then dry-heat-stretched to a high magnification through a heating tube.

The fiber yarn obtained in this way has a preferable strength of 3 g/d or more, and is easily decomposed by microorganisms, so it can be said that it is a completely new fiber that will essentially disappear naturally. It is.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

In this example, the tensile strength and tenacity retention of the fibers were determined according to the following method.

Tensile strength and tenacity retention The sample fibers were conditioned in advance at 20°C and 65% relative humidity for 24 hours, and the fiber paper length was 20-1 and the take-up speed was 100 mm/
The tensile strength (A,
g/d) was measured.

On the other hand, the sample was buried in soil, and the tensile strength (B, g/d) of the fiber was measured over time after cooking under the same conditions as above, and the strength retention rate of the fiber was determined by the following formula.

Strong retention rate (%) = -X 100 Moreover, parts in this example are parts by weight.

Example I After dissolving 0,028 parts of oxalic acid as a pH adjuster in 080 parts of DMS, 10 parts of corn starch and a polymerization degree of 3000 were added.
0 parts of completely saponified PVAl (starch/PvA weight ratio, 50150) was dispersed, and while passing nitrogen,
It was heated to 80°C and dissolved. At this time, the viscosity of the obtained spinning dope was 240 poise (atloo°C). This spinning stock solution was kept warm at 100°C, and
(m, number of holes: 50). The spun yarn is 5~
It was introduced into a methanol bath via a 20 mm air atmosphere and allowed to coagulate. The undrawn yarn obtained here was washed with methanol, then cold-stretched to 3.0 times using double rollers, and further, in a heating cylinder at 240°C.
It was stretched 4.0 times. The fiber thus obtained has a single yarn fineness of 3°4d, a tensile strength of 6.4g/d, and an elongation of 4.
．． It was 8%. These starch-PVA fibers were wrapped in a stainless steel frame and buried under 10QII soil, and the decomposition behavior over six months, one year, and one and a half years was investigated based on the strong retention rate of the fibers, and the results were 99.7% and 54.3%. %, 8.2%, resulting in a significant decrease in fiber strength due to decomposition.

Example 2 After dissolving 0.03 parts of oxalic acid (PH adjuster) in 085 parts of DMS, 3 parts of corn starch, 12 parts of completely saponified PVA with a degree of polymerization of 3000, (weight ratio of starch/PVA, 20
/80) and then heated to 80°C while passing nitrogen.
It was heated to dissolve.

At this time, the viscosity of the spinning dope obtained was 220 poise (at
temperature). This spinning dope was kept at 100° C. and spun using a spinneret (diameter: 0.12 mm, number of holes: 50). The spun yarn was introduced into a methanol tank through an air atmosphere of 5 to 20 °C to coagulate it. The undrawn yarn obtained here was washed with methanol, then cold-stretched to 3.0 times using double rollers, and further stretched to 24
The film was stretched 5.0 times in a heating tube at 0°C. The fiber thus obtained had a single yarn fineness of 3.3 d, a tensile strength of 8.7 g/d, and an elongation of 4.6%. These starch-PVA fibers were wrapped in a stainless steel frame and buried under 10 um of soil, and the decomposition behavior over six months, one year, and one and a half years was investigated based on the strong retention rate of the fibers, and the results were 99.8% and 99%.
．． The fiber strength decreased by 6% and 78.2% due to decomposition.

Example 3 After dissolving 0.027 parts of oxalic acid (PH adjuster) in 77 parts of DMSO, 16.1 parts of corn starch and a polymerization degree of 300 were added.
6.9 parts of fully saponified PVA (starch/PVA weight ratio, 70/30) was dispersed and further heated to 80° C. while passing nitrogen to dissolve. At this time, the viscosity of the spinning stock solution obtained was 300 voids (at 100° C.).

This spinning stock solution was kept warm at 100°C, and the spinneret (caliber, 0.1
2■, number of holes: 50). The spun yarn is 5
Through an air atmosphere of ~20 mm, it was introduced into a methanol tank and coagulated. The undrawn yarn obtained here was washed with methanol, and then passed through a double roller to
Cold stretching was performed to double the length, and further stretching was performed to 2.0 times in a heated cylinder at 240°C. The fiber thus obtained had a single yarn fineness of 5.3 d, a tensile strength of 3.2 g/d, and an elongation of 8.6%. These starch-PVA fibers were wrapped in a stainless steel frame and buried under 10 um of soil, and the decomposition behavior over six months, one year, and one and a half years was investigated based on the strong retention rate of the fibers, and the results were 53.2%, 29°6 %, a significant decrease in fiber strength occurred due to decomposition of 8.1%.

[Effects of the Invention] The fiber of the present invention has a function of naturally disintegrating after a certain period of time after the textile product is used. Therefore, even when this textile product is thrown away, it is possible to prevent the spread of environmental pollution.

For this reason, it is particularly useful as a fiber for textile materials such as ropes, strings, strings, and fishing nets.

Claims (2)

[Claims] (1) Biodegradable fiber made of starch and polyvinyl alcohol polymer. (2) The biodegradable fiber according to claim (1), which has a fiber strength of 3 g/d or more.