JP2005146425A - Polylactic acid fiber and woven or knit fabric made thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber having excellent stainproofness and free from water pollution problem. <P>SOLUTION: The fibrous material contains 5-50 wt.% polylactic acid resin having a molecular weight of ≥10,000 and <50,000 and 50-95 wt.% polylactic acid resin having a molecular weight of ≥50,000 and ≤200,000. Preferably, the polylactic acid resin has a melting point of ≥150°C and the polylactic acid fiber has an initial tensile strength of ≥1.5 cN/dtex and a boiling water shrinkage of ≤12%. The polylactic acid fiber is e.g. multifilament, monofilament, flat yarn and staple fiber. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an environmentally friendly antifouling fiber. In particular, antifouling that has a good effect on preventing contamination by various organisms such as microorganisms and animals and plants adhering to the underwater or various parts of various tools such as nets and marine structures, and various tools such as fishing nets. It is about fiber.

  Ship bottom, submarine communication cable, transport pipeline, observation buoy, buoy, oil fence, silt protector, pier, cooling channel for thermal power or nuclear power generation, industrial cooling channel, wave power buoy, ocean development and civil engineering work Equipment, facilities and structures that have been immersed in water for a long time, such as various equipment related to fisheries, fishing nets, fishing gear, etc., include barnacles, mussels, hydro-insects, cell plastics, beetles, sea squirts, sponges, , Algae such as Aosa, Aonori, Shiomidomo, Hibimidoro, Shiogusa, Mill, etc., and aquatic microbes that form slime such as cyanobacteria, diatoms, and bacteria (hereinafter collectively referred to as “fouling organisms”) For this reason, the said apparatus, an instrument, an installation, a structure, etc. suffer various loss.

  When fouling organisms adhere to fish and shellfish aquaculture nets, the durability of the net itself is impaired, or the fouling organisms cover the mesh, preventing the inflow and outflow of seawater, leading to a lack of oxygen in the water. This may cause the cultured fish shellfish to die due to difficulty in breathing, or promote the growth of bacteria and cause damage to the fish shellfish due to the occurrence of fish disease.

  In this way, the attachment of fouling organisms to fiber structures and the like existing in water causes extremely great damage in the industry. Therefore, conventionally, an antifouling paint containing an antifouling agent and a hydrolyzable resin has been used to prevent the attachment of fouling organisms to fiber structures and the like. Examples of antifouling agents include heavy metal compounds such as cuprous oxide and rhodan copper, and carbamic acid compounds such as tetramethylthiuram disulfide and zinc dimethyldithiocarbamate. Hydrolytic resins include TBTO pendant acrylic resins and silyl ester series. An acrylic resin etc. are mentioned. A coating film made of such an antifouling paint gradually decomposes (shaves) due to hydrolysis of the hydrolyzable resin, and an active antifouling agent always appears on the surface of the paint film. Continue to exhibit stable antifouling properties. However, in recent years, there is concern about contamination of seawater by these antifouling agents and eluted resins.

  As a patent for an antifouling agent, Patent Document 1 discloses an antifouling paint comprising a biodegradable polymer and an anatase-type titanium oxide. In this paint, anatase type titanium oxide is used in addition to the resin. However, although it is examined not to be harmful, it is in the natural environment that it exists in the water in the sea or river at high concentration. It is not good, and it is insoluble in water, so if it starts to dissolve in water, it will settle and it will not be understood what kind of effect it will have on the seabed and riverbed organisms. In fact, the effect disappears.

  As a patent for the fibrous material, Patent Document 2 discloses a fiber in which the surface of the fiber is covered with at least one of a biodegradable resin or a water-soluble resin. However, this patent does not define the molecular weight of the polylactic acid resin, and the duration of the effect is unclear.

JP 2001-114616 A JP 2003-193372 A

  In view of the above problems, an object of the present invention is to provide a fibrous material that can control the durability of the antifouling effect and is gentler to the natural environment.

  An object of the present invention is to contain a polylactic acid resin having a molecular weight of 10,000 to less than 50,000 in a weight ratio of 5 to 50% by weight and a polylactic acid resin having a molecular weight of 50,000 to 200,000 in weight ratio of 50 to 95% by weight. Achievable with fibrous material.

  An effect of the present invention is to provide a fibrous material that hardly affects the natural environment.

  Furthermore, the antifouling effect can be controlled by using this fibrous material.

  The fibrous material of the present invention comprises a polylactic acid resin having a molecular weight of 10,000 to less than 50000 in a weight ratio of 5 to 50% by weight, and a polylactic acid resin having a molecular weight of 50,000 to 200,000 in weight ratio of 50 to 95% by weight. It is a fibrous material to contain.

  In general, polylactic acid-based resins are difficult to hydrolyze when the molecular weight increases (that is, the degree of polymerization increases). If the degree of polymerization of the polylactic acid resin is simply increased in order to improve the tensile strength of the fibrous material, the hydrolysis (including biodegradation) rate required for the antifouling paint cannot be obtained. On the other hand, if the degree of polymerization of the polylactic acid resin is simply lowered in consideration of the hydrolysis (including biodegradation) rate, the tensile strength of the fibrous material is lowered, and the hydrolysis proceeds too much when used in a fabric. The period is shortened. For the polyester resin of the present invention, in order to obtain practically sufficient fiber physical properties and to control the antifouling property, the molecular weight of the polylactic acid resin is examined in detail, and the molecular weight is from 10,000 to less than 50,000, from 50,000 to 200,000. The polylactic acid resin having a molecular weight of 10,000 or more and less than 50000 is 5 to 50% by weight and the polylactic acid resin having a molecular weight of 50,000 or more and 200,000 or less is 50 to 95% by weight. We found that it is necessary to contain.

  That is, in order to satisfy both of these two properties of an appropriate hydrolysis rate, strength as a fiber, and shrinkage rate, the molecular weight distribution of the polylactic acid-based resin is required. And it became the mixture of the polylactic acid-type resin molecule | numerator which has several different hydrolysis rates by this, and had the antifouling effect over the long term from the beginning.

  In the initial stage, polylactic acid having a molecular weight of 10,000 or more and less than 50,000 can be gradually hydrolyzed to obtain antifouling properties. However, hydrolysis of polylactic acid having a molecular weight of 50,000 or more and 200,000 or less has not begun and is sufficient as a fibrous material. It has a strong strength. Thereafter, the hydrolysis of the polylactic acid having a molecular weight of 50,000 to 200,000 starts gradually, so that a fibrous material having antifouling properties can be obtained while maintaining the strength for 2 to 5 years.

  This is because the water-soluble lactic acid and lactic acid oligomer (polylactic acid water-soluble low molecular weight component) has an effect as an antifouling agent, and the polylactic acid resin on the fiber surface is little by little. It is thought that it is an antifouling effect due to both the effect of removing attached dirt by hydrolyzing, and the antifouling effect is maintained by adjusting the ratio of polylactic acid resin in each molecular weight range Can be controlled.

When blending polylactic acid having a molecular weight of less than 10,000, hydrolysis progresses during spinning, resulting in a decrease in yarn quality. In addition, when stored in a warehouse or the like, the low molecular weight substance in the filaments hydrolyzes, causing problems such as a decrease in strength.

  If a polylactic acid having a molecular weight exceeding 200,000 is used, it is impossible to obtain a yarn having a low warp viscosity at the time of spinning and having a sufficient string.

  The molecular weight of the present invention is a weight average molecular weight (MW).

  The polylactic acid resin used in the present invention preferably has a melting point of 150 ° C. or higher. Polylactic acid resins are known to have different melting points depending on the ratio of the D / L isomer, which is an optical isomer. However, if the melting point is 150 ° C. or higher, the fibrous material has excellent crystallinity and sufficient strength. I can get it. On the other hand, if it is 150 ° C. or lower, it becomes amorphous and the strength is lowered, and it is impossible to obtain a fabric having a low molding temperature and sufficient for practical use.

  The said polylactic acid-type resin says resin containing 50 weight% or more of lactic acid components as a monomer unit. That is, not only 100% lactic acid polymer but also other components such as polyhydric alcohol, polyhydric carboxylic acid, acid anhydride and hydroxycarboxylic acid other than lactic acid are copolymerized singly or plurally as long as the object of the present invention is achieved. May be.

  The initial tensile strength of the fibrous material of the present invention is preferably 1.5 cN / dtex or more. If the initial tensile strength is 1.5 cN / dtex or more, the workability when making a fabric is good and there is no practical problem. The preferred range of the initial tensile strength varies depending on the fiber form, but it is more preferably 3.0 cN / dtex or more for monofilar and multifilament, and 1.80 cN / dtex or more for flat yarn.

  The boiling water shrinkage of the fibrous material is preferably 12% or less. If it is 12% or less, the shrinkage stability during molding is excellent and suitable. More preferably, it is 10% or less.

  The fibrous material of the present invention is made by blending polylactic acid resins having different molecular weights, and the relative viscosity of the fiber is preferably 2.2 to 4.0. Within the above range, a sufficient initial strength can be obtained, and a fibrous material having good moldability and excellent antifouling property can be obtained.

If necessary, additives such as various pigments, inorganic compounds, crystal nucleating agents, and plasticizers can be blended in the fiber.

  The fibrous material of the present invention is preferably multifilament, processed yarn, monofilament, flat yarn, or staple. Further, the fibrous material may be used as it is, but it can also be used as a woven or knitted fabric.

  When used as a woven or knitted fabric, it can be used in combination with other materials, and it is preferable to use the fibrous material in an amount of 30% or more, and more preferably 50% or more.

  Hereinafter, although the synthesis example of the polyester resin for antifouling paints of the present invention and the example of antifouling paints are explained, the present invention is not limited at all by these synthesis examples and examples.

(Relative viscosity ηrel)
The sample was dissolved in a mixed solvent of phenol / tetrachloroethane = 60/40 (mass ratio) to a concentration of 1 g / dL, and the relative viscosity was measured at 20 ° C. using an Ubbelohde viscometer.

(Measurement of strong elongation)
Using a tensile tester (RTM-100) manufactured by Shimadzu Corporation, a tensile test was performed at a sample length of 20 cm and a speed of 20 cm / min. The breaking strength was taken as tensile strength, and the breaking elongation was taken as elongation.

(Melting point)
Using a Rigaku Thermoplus DSC8230, the temperature was measured at a temperature rising rate of 10 ° C./min in a temperature range of 30 ° C. to 200 ° C.

(Molecular weight measurement)
It measured by the comparison with a polystyrene standard sample with the gel permeation chromatography measuring apparatus (Hereafter, it abbreviates as GPC. HLC8120 by Tosoh Corporation, column temperature 40 degreeC, tetrahydrofuran solvent).

(Anti-fouling test)
A 48cm square net was made with the polylactic acid fiber obtained, immersed in 1.5m below the water surface off Hofu in the Seto Inland Sea, and soiled by organisms after 1, 6 and 24 months. Evaluated. Visually judge the contamination by living organisms, 5 stages from very good (very little) to very bad (very much) (5-very good, 4-good, 3-somewhat bad, 2-bad, 1-Very poor).

(Preparation Example 1)
A polymer P1 was obtained by blending 10% of polylactic acid having a melting point of 168 ° C. and a molecular weight of 27,000 with a biaxial kneader with 10% of polylactic acid having a melting point of 170 ° C. and a molecular weight of 14,000.

(Preparation Example 2)
A polymer P2 was obtained by blending 30% of polylactic acid having a melting point of 168 ° C. and a molecular weight of 27000 with a biaxial kneader with 70% of polylactic acid having a melting point of 170 ° C. and a molecular weight of 14,000.

(Preparation Example 3)
A polymer P3 was obtained by blending 50% of polylactic acid having a melting point of 168 ° C. and a molecular weight of 27000 with a biaxial kneader with 50% of polylactic acid having a melting point of 170 ° C. and a molecular weight of 14,000.

(Preparation Example 4)
A polymer P4 was obtained by blending 2% of polylactic acid having a melting point of 168 ° C. and a molecular weight of 27000, and 98% of polylactic acid having a melting point of 170 ° C. and a molecular weight of 140000 in a biaxial kneader.

(Preparation Example 5)
Polymer P5 was obtained by blending 60% of polylactic acid having a melting point of 168 ° C. and a molecular weight of 27000 with a biaxial kneader with 60% of polylactic acid having a melting point of 170 ° C. and a molecular weight of 14,000.

(Preparation Example 6)
Polymer P6 was obtained by blending 50% of polylactic acid having a melting point of 168 ° C. and a molecular weight of 8000 with 50% of polylactic acid having a melting point of 170 ° C. and a molecular weight of 14,000 using a biaxial kneader.

(Preparation Example 7)
Polymer P7 was obtained by blending 10% polylactic acid having a melting point of 168 ° C. and a molecular weight of 27000 with a biaxial kneader with 90% polylactic acid having a melting point of 170 ° C. and a molecular weight of 250,000.

(Examples 1-3)
The polymers of Preparation Examples 1 to 3 were melted at 220 ° C. using a single screw extruder, and the nozzle nozzle was 1.2 m.
Extruded from m × 18 pieces. After passing through the water cooling bath, it is stretched one step by 5.5 times with 94 ° C hot water, further stretched by 1.2 times with hot water at 98 ° C, and heat-set with hot air at 130 ° C for 500 dtex. A monofilament was produced. Table 1 shows the yarn quality and antifouling property.

  In Examples 1 to 3, filaments having good yarn quality and antifouling properties could be obtained.

(Comparative Examples 4-7)
The polymers of Preparation Examples 4 to 7 were melted at 220 ° C. using a single screw extruder and extruded from a nozzle nozzle of 1.2 mm × 18. After passing through the water cooling bath, it is stretched one step by 5.5 times with 94 ° C hot water, further stretched by 1.2 times with hot water at 98 ° C, and heat-set with hot air at 130 ° C for 500 dtex. A monofilament was produced. Table 2 shows the yarn quality and antifouling property.

Since Comparative Example 1 has a low blend ratio of the low-molecular polymer, the antifouling property is poor one month after installation, and after that, although improvement was gradually seen, the algae attached at the initial stage did not peel off and the antifouling property was poor. It became.
In Comparative Example 2, the initial antifouling property was good due to the high blend ratio of low molecular weight polylactic acid. It is difficult to do.

  In Comparative Example 3, since the viscosity of the low molecular weight polylactic acid is too low, depolymerization occurs at the time of spinning, resulting in poor spinning properties such as frequent yarn breakage during spinning. Moreover, in the antifouling test, the decomposition progressed too much, and the test could not be continued after approximately 6 months.

  In Comparative Example 4, since the molecular weight of the high molecular weight polylactic acid is high, the melt viscosity at the time of spinning is low and the spinnability is poor. Therefore, yarn breakage occurs frequently and the spinnability is poor. In the antifouling test, the initial condition was good, but the antifouling property gradually disappeared because hydrolysis of the high molecular weight polylactic acid did not proceed.

  The fibrous material excellent in antifouling property of the present invention can provide a fibrous material that has excellent antifouling performance for a long period of time and is less contaminated with seawater, river water and the like.

Claims (5)

A fibrous material containing a polylactic acid resin having a molecular weight of 10,000 to less than 50000 in a weight ratio of 5 to 50% by weight and a polylactic acid resin having a molecular weight of 50,000 to 200,000 in weight ratio of 50 to 95% by weight.   The fibrous material according to claim 1, wherein the melting point of the polylactic acid resin is 150 ° C or higher.   The fibrous material according to any one of claims 1 and 2, wherein the initial tensile strength of the polylactic acid fibrous material is 1.5 cN / dtex or more and the boiling water shrinkage is 12% or less.   The fibrous product according to any one of claims 1 to 3, wherein the polylactic acid fibrous product is composed of any one of a multifilament, a monofilament, a flat yarn, and a staple.   A woven or knitted fabric using the polylactic acid fibrous material according to any one of claims 1 to 4.