JPH09195122A - Biodegradable fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain biodegradable fiber which has high biodegradability, practi cal levels of mechanical strength and heat resistance and is useful as a fiber material for industrial purpose, for example, in fishery, agriculture and civil engineering. SOLUTION: A resin composition comprising (A) 100 pts.wt. of an aliphatic polyester, preferably a polyester from succinic acid and 1,4-butanediol and (B) 1-200 pts.wt. of polycaprolactone is melt-extruded into a biodegradable fiber with a tensile strength of >=2.0g/d. The component B induces the biodegradation of the component A, and a biodegradable fiber which can readily replace the conventional polyesters with itself in the application without any trouble is obtained at a relatively inexpensive cost.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fibrous body comprising a resin composition of an aliphatic polyester resin and polycaprolactone, which is excellent in biodegradability, mechanical strength characteristics and heat resistance.

[0002]

2. Description of the Related Art Conventionally, fibers for industrial materials used for fishing, agriculture and civil engineering are required to have strength and weather resistance, and mainly polyamide, polyester, vinylon, polyolefin and the like are used. These are collected after use and are processed by incineration, landfill, recycling, or the like. However, it may be difficult to recover, and the disposal process requires a large amount of money, so in reality it may be left in the sea or mountains. However, these fibers are not self-degrading and cause various pollution when left to stand after use. Not only does it impair the natural landscape, but it is also entangled with and killed by birds and marine life seafood, divers, etc. that exist in the natural world, or by being entangled with the screw etc. of a ship, which also causes ship accidents and the like.

As a method for solving this, fibers using a biodegradable material have been considered. Examples of biodegradable polymers include polysaccharides such as cellulose and chitin, proteins and polypeptides such as cut gut (intestinal line) and regenerated collagen, poly (α-oxy acid) such as polyglycolide or polylactide, poly ( [beta] -hydroxyalkanoate), poly [epsilon] -caprolactone, and other aliphatic polyesters are used as raw materials for fibers.

[0004]

However, in order to produce fibers from these raw materials, in the case of polysaccharides and polypeptides, they must be produced by the wet spinning method, and poly (α-oxy acid) is used. However, since the cost of the material is extremely high, the manufacturing cost is high, and there is a problem in that high strength fibers cannot be obtained.

Of these, poly ε-caprolactone is a relatively inexpensive biodegradable synthetic polymer and can be melt-spun. However, its melting point is as low as 60 ° C., so that its use is partially limited.

As an inexpensive biodegradable material, polyethylene blended with starch has been investigated, and a film formed by blending linear low density polyethylene with about 6% starch has been put into practical use as a shopping bag. There is. However, even when fibers are produced from polyethylene mixed with such starch, the entire product is not completely biodegraded, and mechanical properties such as strength of the product are significantly inferior, and it is used as an industrial material requiring high strength. You cannot do it.

On the other hand, a microbial product in the natural world is poly (β-hydroxyalkanoate), which is a kind of thermoplastic polyester. The melting point of this product is 130 to 1
It is 80 ° C., which is a practical melting point in fiber production and use. It is reported that a fiber was produced from this poly (β-hydroxyalkanoate), and a monofilament having a tensile strength of 3 g / d was obtained (Nikkan Kogyo Shimbun, January 17, 1992). However, there is no report that a multifilament having practically sufficient strength was obtained. The reason is that the crystallization rate of poly (β-hydroxyalkanoate) is much slower than that of polyamide, polyethylene terephthalate, etc., so that fusion occurs between filaments during melt spinning and winding, resulting in unwinding from the package. Because it will be difficult. If spinning is carried out under conditions such that crystallization is sufficiently promoted so as not to cause fusion, drawing becomes difficult and only a yarn having low strength can be obtained.

Further, when an aliphatic polyester or the like composed of succinic acid and 1,4-butanediol is polymerized by polycondensation, the reaction is carried out under severe conditions of high temperature and high pressure in the latter half of the production process. For this reason, depolymerization of the polyester resin, which originally has poor heat stability, occurs, and it is difficult to obtain a high molecular weight product. Therefore, the mechanical strength characteristics of the obtained fiber are insufficient.

Under these circumstances, there is a strong demand for the development of fibers that are relatively inexpensive, can be put to practical use, have mechanical strength characteristics and heat resistance, and are excellent in biodegradability.

[0010]

Means for Solving the Problems The present inventor has conducted extensive studies on a composition composed of an aliphatic polyester resin, and as a result, a fiber composed of a resin composition containing a predetermined amount of polycaprolactone has been used for conventional applications. The present invention has found that a fiber having mechanical strength properties and heat resistance that can be substituted without problems, and that the incorporation of polycaprolactone induces biodegradation of an aliphatic polyester resin, resulting in a fiber exhibiting high biodegradability, Has been completed.

That is, the present invention relates to an aliphatic polyester 1
The present invention provides a biodegradable fiber having a tensile strength of 2.0 g / d or more, which is characterized by comprising a polyester resin composition in which 1 to 200 parts by weight of polycaprolactone is mixed with 00 parts by weight. Also, aliphatic polyester 100
The present invention provides a biodegradable fiber containing 40% by weight or more of a polyester resin composition containing 1 to 200 parts by weight of polycaprolactone with respect to parts by weight and having a tensile strength of 2.0 g / d or more. Hereinafter, the present invention will be described in detail.

The polyester resin composition used in the present invention comprises a resin composition of an aliphatic polyester resin and polycaprolactone. Examples of the aliphatic polyester resin include a polyester resin obtained from succinic acid and 1,4-butanediol, a polyester resin obtained from succinic acid and ethylene glycol, a polyester resin obtained from oxalic acid and neopentyl glycol, and oxalic acid. Examples thereof include a polyester resin obtained from 1,4-butanediol and a polyester resin obtained from oxalic acid and ethylene glycol, but a high melting point is preferable, and a succinic acid and 1,4-butanediol are preferable. It is a polyester resin.

The number average molecular weight of the aliphatic polyester resin, which is preferable for producing fibers and yarns and ensuring strength, is 30,000.
To 1,000,000, more preferably 70,
It is in the range of 000 to 200,000. If the average molecular weight is 30,000 or less, the mechanical properties are insufficient, and 1,000,
If it is 000 or more, the melt viscosity may be too high in the process of producing the biodegradable fiber, which may cause problems such as difficulty in extrusion.

The polycaprolactone used in the present invention is
Using an active hydrogen-containing compound such as alcohol as an initiator, ε-
Caprolactone obtained by a conventional ring-opening polymerization can be used. The functional number of the initiator is not particularly limited,
A bifunctional or trifunctional one can be preferably used. The number average molecular weight of polycaprolactone is preferably in the range of 1,000 to 200,000, particularly preferably in the range of 5,000 to 100,000. Although polycaprolactone having a number average molecular weight of more than 200,000 can be used in the present invention without any problem, it is generally difficult and unrealistic to obtain such a polycaprolactone having a very high molecular weight. As the polycaprolactone to be used, a copolymer using a comonomer such as valerolactone, glycolide, or lactide can be used in addition to the ε-caprolactone homopolymer.

The polyester resin composition used in the present invention is preferably a mixture of 100 parts by weight of aliphatic polyester resin and 1 to 200 parts by weight of polycaprolactone, more preferably 100 parts by weight of aliphatic polyester resin. On the other hand, 4 to 55 parts by weight of polycaprolactone is mixed. By mixing in this range, a biodegradable fiber having excellent biodegradability, mechanical strength characteristics and heat resistance can be obtained.

If desired, the biodegradable fiber of the present invention may be mixed with other biodegradable resin or an inorganic substance. The mixing ratio of the above polyester resin composition and other components is such that the polyester resin composition is 40% by weight or more based on the obtained resin composition (the total of the other components and the polyester resin composition is 100% by weight). Is preferred,
Particularly preferably, it is 60% by weight or more. Other biodegradable resin components that can be mixed and used in the present invention include:
Examples thereof include polyvinyl alcohol-based resins and copolymer-based resins of 3-hydroxybutyrate and 3-hydroxyvalerate. Examples of other inorganic substances that can be mixed and used in the present invention include calcium carbonate, magnesium carbonate, talc, silica and the like. In addition, polyesters such as low molecular weight polycaprolactone in the above range can be added as a plasticizer, and matting agents, pigments such as carbon black, antioxidants (for example, hindered phenol compounds, hindered amine compounds, phosphorus compounds Etc.), an ultraviolet absorber (for example,
Benzophenol compound, benzotriazole compound,
A salicylate compound, etc.), or in some cases, a compound having a crosslinkable group. Further, a crystal nucleating agent such as boron nitride or titanium dioxide is used in the range of 0.1 to 5.
You may contain 0 weight%.

In order to produce the biodegradable fiber of the present invention as a multifilament, the polyester resin composition can be subjected to a melt spinning method. The temperature of melt spinning is
Although it depends on the number average molecular weight of the polyester resin composition used, it is preferably 140 to 220 ° C.
If the spinning temperature is less than 140 ° C, melt extrusion is difficult,
When it exceeds 220 ° C, the polyester resin composition is significantly decomposed, and it becomes difficult to obtain a high-strength multifilament. The multifilament melt-spun from a spinneret having 10 to 100 holes is air-cooled at room temperature to 80 ° C, and a normal spinning oil for synthetic fibers is applied, and subsequently, cold drawing of one or more steps between rollers is performed. Alternatively, it is subjected to hot stretching. The total draw ratio depends on the required performance of the target multifilament, but the spinning speed is 10 to 1,000.
The draw ratio is 1.2 times or more as m / min. This is because if the spinning speed is less than 10 m / min, crystallization proceeds and drawing becomes difficult, and if the spinning speed is 1,000 m / min or more, fusion between filaments may occur. When the spinning speed is within the above range and the draw ratio is 1.2 times or more, a multifilament of 2.0 g / d or more can be obtained.

In order to produce the biodegradable fiber of the present invention as a monofilament (1,000 d etc.), the polyester resin composition can be subjected to a melt spinning method. The melting temperature is 140 to 220 ° C., the resin extruded from the die is cooled in water at room temperature to 80 ° C., and necking stretching of about 2 to 10 times is performed. Stretching is done in one stage, but 2
It doesn't matter if you go in steps or more. The total draw ratio varies depending on the required performance of the intended monofilament, but a draw ratio of 4 times or more is preferable. This is because a biodegradable fiber having sufficient tensile strength can be obtained at a draw ratio of 4 or more.

The biodegradable fiber of the present invention has a tensile strength of 2.
It is preferably 0 g / d, particularly 3.0 g / d or more. This is because when the tensile strength is 2.0 g / d or less, the practical strength as a fiber is low and the practical strength is insufficient.

The biodegradable fiber of the present invention can be used as it is as a raw yarn, and further, the raw yarn can be woven or knitted into a cloth or a net or twisted to form a rope. can do. The biodegradable fiber of the present invention can be used for fishery materials such as fishing nets, seaweed nets, fishing lines, tree fixing tools, agricultural materials such as ropes, civil engineering materials, and sanitary materials such as hand towels.

[0021]

EXAMPLES The method for producing the biodegradable fiber of the present invention will be specifically shown below, but the present invention is not limited thereto. The tensile strength characteristics were measured according to JIS L1013. As a biodegradability test, the sample was embedded in soil for 2 months and then taken out to check if the fiber lost its shape. When the tensile strength retention rate of the fiber was 50% or less, the biodegradability was determined. Was good.

Example 1 Aliphatic polyester resin of succinic acid and 1,4-butanediol (number average molecular weight 7
70 parts by weight of 10,000) and 30 parts by weight of polycaprolactone (“PLACCEL H7” manufactured by Daicel Chemical Industries, Ltd.) were kneaded to obtain a polyester resin composition. This is 25
Using an extruder having a diameter of mm, the composition was extruded from a die having 16 holes at an extrusion temperature of 200 ° C., and air-cooled while stretching. Then
Draft magnification is set to 200 and further stretched to 2 times to 32d
A multifilament (2d / filament) of was obtained.
The tensile strength of this multifilament is 4g at breaking strength.
/ D and the elongation was 40%. Also, the biodegradability in soil burial was good.

Example 2 Aliphatic polyester resin of succinic acid and 1,4-butanediol (number average molecular weight 7
70 parts by weight of 10,000) and 30 parts by weight of polycaprolactone (“PLACCEL H7” manufactured by Daicel Chemical Industries, Ltd.) were kneaded to obtain a polyester resin composition. This is 25
Using a mm-diameter extruder, it was extruded from a die having 3 holes at an extrusion temperature of 210 ° C., cooled in water at 70 ° C. and then stretched 8 times to obtain a 900 d monofilament. The tensile strength characteristics of this monofilament were a breaking strength of 5.5 g / d and an elongation of 50%. Also, the biodegradability in soil burial was good.

[0024]

According to the present invention, a fiber having practical heat resistance and mechanical strength characteristics and biodegradability is provided. Biodegradable fiber of the present invention, fishery materials, agricultural materials,
It is suitable as a civil engineering material, sanitary material, waste treatment material, etc. After use, it can be completely biodegraded simply by leaving it in the soil or water containing microorganisms. For this reason, special disposal processing is not required and the processing can be simplified, and it is suitable for environmental protection.

Claims (2)

[Claims] 1. A biodegradable fiber having a tensile strength of 2.0 g / d or more, comprising a polyester resin composition in which 1 to 200 parts by weight of polycaprolactone is mixed with 100 parts by weight of an aliphatic polyester. 2. A biodegradable fiber having a tensile strength of 2.0 g / d or more, containing 40% by weight or more of a polyester resin composition in which 1 to 200 parts by weight of polycaprolactone is mixed with 100 parts by weight of an aliphatic polyester. .