JP2007308817A - Net - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a net which uses polylactic acid fibers, has improved hydrolysis resistance, and can be especially suitably used for industry. <P>SOLUTION: This net is characterized by using polylactic acid fibers whose carboxyl terminals are partially or wholly blocked with at least one glycidyl group-containing triazine skeleton compound represented by the general formula (I) (at least one of R<SB>1</SB>to R<SB>3</SB>is glycidyl group, and the remaining groups are selected from H, 1 to 10C alkyl groups, OH, and allyl group) as at least one part of the net. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an environment-friendly net using polylactic acid fibers, and relates to a net that solves the problem of easily hydrolyzable, which has been a problem with conventional nets using polylactic acid fibers.

  In recent years, polylactic acid resin has attracted attention as a resin having a small environmental load even if it is burned or discarded. The reason why polylactic acid is said to be an environmentally friendly material is that it is obtained from non-petroleum raw materials such as plants and has biodegradation characteristics. The biodegradation mechanism of polylactic acid is generally known to start with biodegradation by microorganisms after the molecular weight is reduced by hydrolysis, and it is also well known that the hydrolysis rate is fast.

  Polylactic acid fiber using this polylactic acid resin has a unique luster, good color development and tactile sensation when dyed, and has a unique texture, so it can be used for clothing, interiors, draining bags, seedling mats. In addition, various textile products such as woven and knitted fabrics for civil engineering, grass protection sheets for vegetation, safety nets, and nets for construction are being studied for practical use.

  However, for industrial nets that are often used outdoors, there is a demand for maintaining strength over a certain period of time, so the “fast hydrolysis rate” of polylactic acid has become a problem. The current situation is that it has not been replaced by other materials.

Among the prior arts, technologies for obtaining polylactic acid fibers excellent in hydrolysis resistance are described in Patent Documents 1 to 3, etc., and Patent Document 1 adds a carbodiimide compound to suppress hydrolysis of polylactic acid. In addition, Patent Documents 2 and 3 disclose techniques for suppressing hydrolysis of polylactic acid by adding an oxazoline compound and an epoxy compound, respectively.
JP 2004-332166 A JP 2001-323056 A JP 2001-335626 A

  However, when the carbodiimide compound described in Patent Document 1 is added to obtain a polylactic acid fiber, in the polylactic acid fiber manufacturing process, the isocyanate derived from the carbodiimide compound generates a bad odor and the working environment is deteriorated. In addition, the carbodiimide has a problem of increasing the viscosity of the polymer and deteriorating the yarn forming property. In addition, the inventors of the present invention further tried the methods described in Patent Documents 2 and 3, and as a result, the reactivity between the compound and the carboxyl terminal was poor, and the normal spinning method was insufficient in blocking the carboxyl terminal. there were. Then, this invention makes it a subject to solve the degradation problem by the hydrolysis which was a big problem with the conventional polylactic acid fiber.

  As a result of intensive studies on the above-mentioned problems by the present inventors, at least a polylactic acid fiber represented by the general formula (I) in which a part or all of the carboxyl terminals are blocked with at least one compound is included. It was found that a part of the net solves the above-mentioned problems.

(Here, at least one of R _{1 to} R ₃ is a glycidyl group, and the remainder represents a group selected from hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, and an allyl group.)

The net of the present invention has the following (1) to (4) as preferred modes.
(1) The carboxyl terminal amount of the polylactic acid fiber is 20 equivalent / t or less.
(2) The addition amount of the compound represented by the general formula (I) is 0.1 to 5% by weight of the whole polylactic acid fiber.
(3) The compound represented by the general formula (I) is at least one selected from diallyl monoglycidyl isocyanurate, monoallyl diglycidyl isocyanurate, and triglycidyl isocyanurate.
(4) The entanglement degree of the polylactic acid fiber is 5 to 70.

  According to the present invention, it is possible to solve the degradation problem due to hydrolysis, which has been a big problem in nets using polylactic acid fibers.

  The polylactic acid fiber used in the net of the present invention is obtained from a polylactic acid resin obtained by polymerizing lactic acid mainly composed of L-lactic acid and / or D-lactic acid, and the molecular weight of the polylactic acid resin is not particularly limited. However, if the molecular weight is too high, the spinning property may be deteriorated. If the molecular weight is too low, the necessary strength as a fiber may not be obtained. Therefore, the weight average molecular weight (Mw) is 100,000 to 500,000. It is preferable to be in the range. Moreover, as a more preferable range of Mw, a range of 150,000 to 300,000 can be exemplified.

  The polylactic acid resin may be a copolymer of a component copolymerizable with lactic acid. Examples of the copolymer mainly composed of polylactic acid include the lactic acid, cyclic lactones such as ε-caprolactone, α-oxyacids such as α-hydroxyisobutyric acid and α-hydroxyvaleric acid, ethylene glycol, 1,4 Examples thereof include those obtained by copolymerizing one or more monomers selected from diols such as butanediol and dicarboxylic acids such as succinic acid and sebacic acid. The proportion of copolymerization is not particularly limited, but the monomer to be copolymerized is preferably 100 parts by weight or less, more preferably 1 to 50 parts by weight with respect to 100 parts by weight of lactic acid.

  Further, the polylactic acid fiber of the present invention may be blended with a polylactic acid resin and a blendable thermoplastic polymer, and as a blendable thermoplastic polymer, polycaprolactone, polybutylene succinate, and An aliphatic polyester polymer such as polyethylene succinate can be exemplified.

  Furthermore, inorganic fine particles and organic compounds can be added to the polylactic acid fiber of the present invention as necessary, such as a matting agent, a flame retardant, a heat resistance agent, a light resistance agent, an ultraviolet absorber, and a color pigment. However, in view of recent environmental problems, avoid blends of petroleum-based polymers, copolymerization of the components as much as possible, and various additives are compounds that are expected to be a concern as well as heavy metal compounds and environmental hormone substances. It is preferable that none of the above is used.

  In addition, the polylactic acid fiber of the present invention preferably contains at least one colorant in advance in order to avoid strength reduction and environmental contamination due to the dyeing process. The colorant added to the polylactic acid fiber used in the net of the present invention is a specific inorganic, organic pigment and dye suitable for the polylactic acid fiber, specifically titanium oxide, carbon black, cyanine, styrene, Examples include, but are not limited to, phthalocyanine, anthraquinone, perinone, isoindolinone, anthraquinone, berylone, isoindolinone, quinophthalone, quinocridone, and thioindigo compounds. It is not a thing. The content of the colorant is preferably 0.01 to 4% by weight. When the addition amount of the colorant is less than 0.01% by weight, the color tone is insufficient, and when it exceeds 4% by weight, it is difficult to obtain the required strength. The addition amount of the colorant is more preferably from 0.1 to 0.6% by weight based on the polymer, and still more preferably from 0.3 to 0.5%.

  The polylactic acid fiber of the present invention contains 0.1 to 5% by weight, more preferably 0.5 to 3% by weight of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide in order to improve wear resistance. May be. If it is less than 0.1% by weight, the effect of improving the wear resistance cannot be sufficiently obtained, and if it exceeds 5% by weight, it is difficult to obtain the required strength. By setting the content of the fatty acid bisamide and / or the alkyl-substituted fatty acid monoamide in the above range, the slipperiness of the fiber surface can be improved and excellent wear resistance can be imparted. Fatty acid bisamide refers to a compound having two amide bonds in one molecule such as saturated fatty acid bisamide, unsaturated fatty acid bisamide, aromatic bisamide, etc., for example, methylene biscaprylic amide, methylene biscapric amide, methylene bisamide. Lauric acid amide, methylene bis myristic acid amide, methylene bis palmitic acid amide, methylene bis stearic acid amide, methylene bis isostearic acid amide, methylene bis behenic acid amide, methylene bis oleic acid amide, methylene bis erucic acid amide, ethylene bis Caprylic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bismyristic acid amide, ethylene bispalmitic acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid Amide, Ethylene bis behenic acid amide, Ethylene bis oleic acid amide, Ethylene bis erucic acid amide, Butylene bis stearic acid amide, Butylene bis behenic acid amide, Butylene bis oleic acid amide, Butylene bis erucic acid amide, Hexamethylene Bistearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisoleic acid amide, hexamethylene biserucic acid amide, m-xylylene bisstearic acid amide, m-xylylene bis-12-hydroxystearic acid amide, p- Xylylene bis-stearic acid amide, p-phenylene bis-stearic acid amide, p-phenylene bis-stearic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, N, N′- Giole Luadipic acid amide, N, N′-dioleyl sebacic acid amide, N, N′-distearyl isophthalic acid amide, N, N′-distearyl terephthalic acid amide, methylene bishydroxystearic acid amide, ethylene bishydroxystearic acid amide , Butylene bishydroxystearic acid amide, hexamethylene bishydroxystearic acid amide, etc., and alkyl-substituted fatty acid monoamides are compounds having a structure in which amide hydrogen such as saturated fatty acid monoamides and unsaturated fatty acid monoamides are replaced with alkyl groups. For example, N-lauryl lauric acid amide, N-palmityl palmitic acid amide, N-stearyl stearic acid amide, N-behenyl behenic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N- Examples include oleyl stearic acid amide, N-stearyl erucic acid amide, and N-oleyl palmitic acid amide. The alkyl group may have a substituent such as a hydroxyl group introduced into its structure, for example, methylol stearamide, methylol behenic acid amide, N-stearyl-12-hydroxystearic acid amide, N-oleyl-12-hydroxystearic acid amide and the like are also included in the alkyl-substituted fatty acid monoamide of the present invention. Of these, fatty acid bisamides can be more preferably used because they are less reactive with polylactic acid because of the lower reactivity of amides, and are high in heat resistance and difficult to sublimate because of their high molecular weight. The fatty acid bisamide and the alkyl-substituted fatty acid monoamide may be added singly or a plurality of components may be mixed and used.

  The polylactic acid fiber used for the net of the present invention needs to be partially or entirely blocked with at least one compound represented by the general formula (I). A part or all of the carboxyl terminal of the polylactic acid fiber used for the net is blocked by at least one compound represented by the general formula (I), so that the hydrolysis resistance of the present net is greatly improved. To do.

The compound represented by the general formula (I) is a 1-3 functional glycidyl-modified compound having a triazine skeleton. Among the compounds represented by the general formula (I), at least one of R _{1 to} R ₃ is a glycidyl group. Need to be. When the triazine skeleton has 1 to 3 glycidyl groups, it reacts with carboxyl end groups with high efficiency even in spinning of polylactic acid fibers molded at a relatively low temperature. Moreover, since it does not thicken like a carbodiimide compound, it shows excellent mechanical properties and yarn-forming properties even after end-capping without hindering the orientation of the molecular chain in the melt spinning or drawing process. Further, the compound has high heat resistance, and there is no problem of coloring even if it is molded at a high temperature, and there is no generation of odor that deteriorates the working environment if the addition amount suggested in the present invention.

In addition, among R < ₁ > -R < ₃ >, Preferably a glycidyl group is 1-2 pieces, More preferably, it is one piece. Of course, a plurality of compounds having different numbers of glycidyl groups may be mixed (usually, a mixture having 1 to 3 glycidyl groups is distributed in the synthesis step of the general formula (I)).
Further, among R _{1 to} R ₃ , groups other than the glycidyl group are groups selected from hydrogen, alkyl groups having 1 to 10 carbon atoms, hydroxyl groups, and allyl groups. Here, the number of carbon atoms in the alkyl group should be small, and it is preferably 1 to 5 carbon atoms. Among the above, diallyl monoglycidyl isocyanurate (hereinafter referred to as DAMGIC), monoallyl diglycidyl isocyanurate (hereinafter, referred to as DAMGIC) as the compound represented by the general formula (I) in terms of excellent end capping properties and fiber mechanical properties. In the following, MADGIC) and triglycidyl isocyanurate (hereinafter referred to as TGIC) are preferably used.

  In addition, the polylactic acid fiber used in the net of the present invention has a low carboxyl group terminal concentration because part or all of the carboxyl group at the end of the polylactic acid resin is blocked with the compound of the general formula (I). It is. Here, the carboxyl group terminal concentration refers not only to the carboxyl group terminal of the polymer, but also to the total amount of carboxyl group terminals including those derived from residual oligomers and monomers. In the present invention, in order to provide sufficient hydrolysis resistance, the carboxyl group terminal concentration is preferably 20 equivalent / t or less, more preferably 15 equivalent / t or less, still more preferably 10 equivalent / t or less, particularly Preferably it is 0-5 equivalent / t.

In order to maintain the hydrolysis resistance, it is preferable to leave the unreacted compound represented by the general formula (I). By designing in such a manner, the terminal end of the carboxyl group newly formed by hydrolysis is also blocked. The carboxyl group terminal concentration can be controlled by the amount of the compound represented by the general formula (I). Here, the addition amount of the compound of the general formula (I) is preferably 1.05 times or more equivalent to the total carboxyl group terminal amount of the polylactic acid fiber as an epoxy group equivalent. Therefore, the amount of the compound added depends on the total amount of terminal carboxyl groups of the polylactic acid resin used as a raw material, but the amount of the compound represented by the general formula (I) is usually 0 based on the whole polylactic acid fiber. .1 to 5% by weight. In addition, among R _{1 to} R ₃ of the compound represented by the general formula (I), when the number of glycidyl groups is 2 to 3, the Mw / Mn of the polymer is decreased by chain connection or crosslinking reaction of the polylactic acid resin. It tends to grow. On the other hand, if the unreacted material is excessive, it will be discharged out of the fiber system in the melt spinning or net manufacturing process and will not be used for its original purpose. Therefore, the addition amount of the compound represented by the general formula (I) is preferably 0.2 to 5% by weight, and preferably 0.3 to 3% by weight with respect to the total amount with the polylactic acid resin. More preferred. More preferably, it is 0.4-2 weight%.

  In addition to the compound represented by the above general formula (I), a compound having an oxazoline group, a carbodiimide group, an aziridine group, an imide group and an isocyanate group that are reactive with the carboxyl group terminal is used in combination. Also good. Specific examples of such a compound include diisopropylphenylcarbodiimide and phenylenebisoxazoline.

  Further, in order to efficiently react the compound represented by the general formula (I) with the carboxyl terminal group, a metal salt of carboxylic acid, particularly an alkali metal compound, an alkaline earth metal compound, a tertiary amine compound, Examples include imidazole compounds, quaternary ammonium salts, phosphine compounds, phosphonium salts, phosphate esters, organic acids, Lewis acids, and specific examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, Sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, Sodium phenyl borohydride, sodium benzoate Lithium, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, sodium salt of phenol, Alkali metal compounds such as potassium, lithium and cesium salts, calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, acetic acid Alkaline earth metal compounds such as barium, magnesium acetate, strontium acetate, calcium stearate, magnesium stearate, strontium stearate, triethylamine, tributylamine, trihexylamine, triamylamine Triethanolamine, dimethylaminoethanol, triethylenediamine, dimethylphenylamine, dimethylbenzylamine, 2- (dimethylaminomethyl) phenol, dimethylaniline, pyridine, picoline, 1,8-diazabicyclo (5,4,0) undecene-7 Tertiary amines such as 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-ethyl-4-methylimidazole, imidazole compounds such as 4-phenyl-2-methylimidazole, tetramethylammonium chloride, tetraethylammonium Chloride, tetrabutylammonium bromide, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tripropylbenzylammonium chloride Quaternary ammonium salts such as rholide, N-methylpyridinium chloride, phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, tetramethylphosphonium bromide, tetrabutylphosphonium bromide, tetraphenylphosphonium bromide, ethyltriphenyl Phosphonium salts such as phosphonium bromide, triphenylbenzylphosphonium bromide, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, Octyl diphenyl phosphate , Phosphoric acid esters such as tri (p-hydroxy) phenyl phosphate, tri (p-methoxy) phenyl phosphate, organic acids such as oxalic acid, p-toluenesulfonic acid, dinonylnaphthalenedisulfonic acid, dodecylbenzenesulfonic acid, Examples thereof include Lewis acids such as boron fluoride, aluminum tetrachloride, titanium tetrachloride, and tin tetrachloride, and these can be used alone or in combination. Among them, it is preferable to use an alkali metal compound, an alkaline earth metal compound, a phosphine compound, and a phosphate ester, and in particular, an alkali metal or an organic salt of an alkaline earth metal can be preferably used. Particularly preferred compounds are sodium stearate, potassium stearate, calcium stearate, magnesium stearate, sodium benzoate, sodium acetate, potassium acetate, calcium acetate and magnesium acetate. Further, an organic salt of an alkali metal or alkaline earth metal having 6 or more carbon atoms is preferable, and adding a catalyst such as sodium stearate, potassium stearate, calcium stearate, magnesium stearate, sodium benzoate can increase the reaction efficiency. This is preferable. It is also preferable to use a catalyst based on lactic acid such as sodium lactate, calcium lactate and magnesium lactate because of its good compatibility with polylactic acid. In addition, a catalyst having a relatively large molecular weight such as a metal stearate can be used alone or in combination for the purpose of preventing the heat resistance of the resin from being lowered due to the addition of the catalyst. In addition, it is preferable to add 5-2000 ppm with respect to a fiber, when the addition amount of this catalyst controls dispersibility and reactivity. More preferably, it is 10-1000 ppm, More preferably, it is 20-500 ppm.

  Further, the cross-sectional shape of the polylactic acid fiber used in the net of the present invention is not limited at all, and is a flat cross-section, a trilobal cross-section, a hollow cross-section, a Y-shaped cross section, a rice-shaped cross section, a C-shaped cross section, a W-shaped cross section, a triangle. A cross section or a combination thereof can be employed. By making the cross-sectional shape an atypical cross section, it is possible to impart softness, swelling, bulkiness, lightness, heat retention, and the like.

  The polylactic acid fiber used in the net of the present invention can adopt monofilament, multifilament, slit yarn and the like. There is no particular limitation on the fineness, and the fineness may be appropriately changed according to the application. The range of the total fineness that can be used is 20 to 10000 dtex, preferably 300 to 3000 dtex, and the single yarn fineness range is 0.02 to 10,000 dtex, preferably 0.1 to 3000 dtex. it can. When the total fineness is less than the above range, the productivity is poor, and when the total fineness is more than the above range, for example, there is a possibility that the cooling ability is insufficient during melt spinning and the spinning performance is deteriorated.

  The polylactic acid fiber used in the net of the present invention has a strength of 1.5 cN / dtex or more, more preferably 2.5 cN / dtex or more, and further preferably 3.0 cN / dtex from a practical viewpoint. On the other hand, the upper limit of the strength is 9.0 cN / dtex or less from the viewpoint that the present technology can be stably manufactured. Moreover, what is necessary is just to select elongation suitably by need as needed, for example, the range of 10 to 300% can be illustrated. Furthermore, if it is 10 to 100% as a preferable range, it is possible to obtain a net having high strength and excellent dimensional stability, and if it is 100 to 300%, it is possible to impart flexibility to the net. The boiling water shrinkage of the polylactic acid fiber (hereinafter sometimes abbreviated as boiling) is preferably 0 to 20% because the dimensional stability of the net is improved. The above-described fiber properties can be controlled by spinning temperature, spinning speed, stretching temperature, stretching ratio, and the like.

  The polylactic acid fiber used for the net of the present invention as described above can be produced by the production method described below.

  The production method of the polylactic acid resin used as the raw material for the polylactic acid fiber is not particularly limited, and is a method described in JP-A-6-65360 (direct dehydration condensation method) or a method described in JP-A-7-173266. (Method of copolymerizing and transesterifying at least two kinds of homopolymers in the presence of a polymerization catalyst), a method described in US Pat. No. 2,703,316 (dehydrating lactic acid once, For example, an indirect polymerization method in which ring-opening polymerization is performed after forming the polymer can be employed.

  For example, in the case of TGIC, the compound represented by the above general formula (I) can be produced by reacting isocyanuric acid and epichlorohydrin under a catalyst. Note that the smaller the amount of residual epichlorohydrin in the TGIC, the less the volatilization during melt molding, which is preferable. The concentration of epichlorohydrin in TGIC is preferably 0 to 1000 ppm, more preferably 0 to 500 ppm, and still more preferably 0 to 200 ppm.

  An example of a typical direct melt spin drawing process is shown in FIG. 1 in order to detail the method for producing polylactic acid fibers. The process of FIG. 1 is a “pre-stretch-three-stage stretch-relax” method, but of course, as long as the above requirements are satisfied, the method for producing polylactic acid fibers used in the net of the present invention is not limited to this process. A method of temporarily winding an undrawn yarn and then subjecting it to a drawing step, a high-speed spinning method, or the like can be freely employed.

  The polylactic acid resin whose carboxyl terminal is blocked with the compound represented by the above general formula (I) is added to the polylactic acid resin with the compound represented by the above general formula (I) and mixed in a molten state or a solution state. For example, a method in which the compound represented by the general formula (I) is added and stirred and reacted in the molten state immediately after the polycondensation reaction of the polylactic acid resin, A method in which a compound represented by the above general formula (I) is added to a lactic acid resin chip and mixed, and then melted and kneaded in a reaction vessel or an extruder, etc., and the general liquefied into a polylactic acid resin with an extruder A method of continuously adding a compound represented by the formula (I), reacting by melt-kneading, and a polylactic acid resin containing a high concentration of the compound represented by the general formula (I) The blend chips obtained by mixing a Homochippu star chips and polylactic acid resin, can be carried out by a method of kneading and reacting the like extruder during spinning.

  When the master chip is produced, the amount of the compound represented by the general formula (I) is preferably 1 to 40% by weight, and 3 to 20% by weight based on the total amount with the polylactic acid resin. It is more preferable that

  Moreover, when using for melt spinning, it is preferable that the water content of the polylactic acid resin is 200 ppm or less in order to suppress hydrolysis of the polylactic acid resin.

  The spinning temperature depends on the melting point of the polylactic acid resin to be used, but it is preferable from the viewpoint of spinning property that spinning is performed at a temperature that is at least 20 ° C. higher than the melting point of the high melting point resin.

  Hereinafter, a method for producing a polylactic acid fiber used in the net of the present invention will be specifically described with reference to FIG.

  Polylactic acid fiber is melt-kneaded with an extruder (2) equipped with a twin-screw extrusion kneader, and introduced into a spinning pack (3) in a nitrogen atmosphere in a hopper (1). , And a method of discharging from a spinneret (4) such as a composite die. When adding the above-mentioned pigment, a method of directly mixing with an extruder or a method of previously preparing a polylactic acid resin master chip containing a high concentration of pigment and blending the chips before melting can be employed.

  Immediately below the spinneret, the upper end is 0 to 15 cm from the spinneret surface, and a range of 5 to 100 cm from the upper end is surrounded by a heating tube and / or a heat insulating tube, and the spinning yarn is placed in a high temperature atmosphere of 200 to 280 ° C. It is preferable to let it pass. The orientation of the spun yarn is relaxed by cooling it through the slow cooling zone (5) in a high temperature atmosphere surrounded by the heating tube and / or the heat insulating tube without immediately cooling the spun yarn. And uniformity of molecular orientation between single fibers can be improved. On the other hand, if it cools immediately without letting it pass in a high temperature atmosphere, the orientation of an undrawn yarn will increase and the orientation degree distribution between single fibers will become large. When such an unstretched yarn is hot-drawn, there is a possibility that a high-strength composite fiber cannot be obtained as a result.

  The unstretched yarn that has passed through the high-temperature atmosphere is then preferably solidified by cooling with a cooling device (6) by blowing air at 10 to 100 ° C, preferably 15 to 75 ° C. When the cooling air is less than 10 ° C., a large cooling device is required separately from the normal device, which is not preferable. In addition, when the cooling air exceeds 100 ° C., the single fiber sway during spinning becomes large, so that the single fibers collide with each other, making it difficult to produce the fibers with good spinning properties. The cooling device (6) may be a horizontal blowing type or an annular blowing type. Moreover, when a high cooling effect is required like a monofilament, a cooling method such as water cooling can be adopted.

  The unstretched yarn that has been cooled and solidified is then applied with an oil agent by an oil supply device (7). The oil agent may be aqueous or non-aqueous, but contains a smoothing agent as a main component, includes a surfactant, an antistatic agent, an extreme pressure agent component, and the like, and removes an active component in the polylactic acid resin. It is preferable to use an oil agent composition. For example, the emulsified component contained in the water emulsion has an action of changing the fiber structure of the polylactic acid fiber, and easily works to generate surface irregularities during stretching. Therefore, it is preferable to use a non-aqueous oil agent. Further, a preferred oil agent composition is, for example, a non-aqueous oil agent obtained by diluting an alkyl ether ester as a smoothing agent component, an alkylene oxide adduct of a higher alcohol as a surfactant component, and an organic phosphate salt as an extreme pressure agent component with a mineral oil. .

  The unstretched yarn to which the oil is applied is wound around the take-up roller (1FR) (8) and taken up. The surface speed of 1FR, that is, the take-up speed is preferably 300 m / min or more, more preferably 500 m / min or more. Polylactic acid fibers can be obtained even at a take-off speed of less than 300 m / min, but are difficult to adopt because of low production efficiency. Although there is no particular upper limit to the take-up speed, the take-up speed is preferably 5000 m / min or less, more preferably 3000 m / min or less in the case of industrially stable production.

  The undrawn yarn taken up at the take-up speed is drawn once or continuously without being taken up. Similarly to 1FR, a Nelson type roller having two rollers as one unit is a take-up roller (2FR) (9), a stretching roller (1DR) (10), a stretching roller (2DR) (11), a stretching roller ( 3DR) (12) and the relaxation roller (RR) (13) are arranged side by side, and the yarn is sequentially wound to perform a drawing heat treatment. Usually, stretching is performed between 1FR and 2FR to focus the yarn. A preferred stretch ratio is in the range of 1 to 7%, more preferably 1 to 5%. 1FR is heated to 50 to 80 ° C., preferably 50 to 70 ° C., and the take-up yarn is preheated and sent to the next drawing step.

  The first stage stretching is performed between 2FR and 1DR, the temperature of 2FR is 80 to 120 ° C, preferably 80 to 110 ° C, and the temperature of 1DR is 90 to 120 ° C, preferably 100 to 120 ° C. When the number of drawing stages is 3, the first stage draw ratio is 20 to 90%, preferably 20 to 50% of the total draw ratio, and when the total draw stage number is 2, the first stage draw ratio is It is set in the range of 30 to 90%, preferably 50 to 90% of the total draw ratio.

  The second stage stretching is performed between 1DR and 2DR, and 2DR is 110 to 160 ° C, preferably 115 to 145 ° C. In the case of two-stage stretching, the remaining stretching of the first-stage stretching ratio is performed between the total stretching ratios. In the case of three-stage stretching, the remaining stretching ratio is divided into two stages. The temperature of 3DR when performing three-stage stretching is 120 to 160 ° C, preferably 130 to 150 ° C. The yarn that has finished the two-stage drawing or the three-stage drawing is subjected to a relaxation treatment of 0 to 10%, preferably 0 to 7%, more preferably 0.5 to 5% with the RR, and is caused by heat drawing. In addition to taking the strain, the highly oriented structure achieved by stretching can be fixed, the orientation of the amorphous region can be relaxed, and the thermal shrinkage rate can be lowered. RR uses a non-heated roller or a roller heated to 160 ° C. or less.

  The basic physical properties of the polylactic acid fiber used in the net of the present invention can be obtained by the above method. However, in order to obtain a high-quality polylactic acid fiber with less generation of fluff, a high-pressure fluid is sprayed on the fiber yarn between 2FR and 1DR where one-stage drawing is performed, and the yarn constituting the fiber Stretching may be performed while confounding the yarn and converging the yarn. The entanglement imparting device (14) for entwining and converging the yarn can use an entanglement nozzle that is used to impart entanglement to the yarn and condense it immediately before winding the yarn. The entanglement imparting device (14) is effective when it is stretched in the first stage, but it may also be performed when stretching the second and third stages in addition to the first stage. The degree of entanglement applied to the polylactic acid fiber is preferably 5 to 70, and more preferably 10 to 60. Thereafter, the polylactic acid fiber is wound up by a winding device (15).

  The polylactic acid fiber used for the net of the present invention can thus be obtained.

  In the net of the present invention, it is essential that polylactic acid fibers derived from non-petroleum raw materials are at least a part of the constituent elements from the viewpoint of reducing the environmental load. In addition, the net of the present invention includes 10 to 100% by weight of polylactic acid fibers in which part or all of the carboxyl ends are blocked with at least one compound represented by the general formula (I), thereby reducing environmental impact. From the viewpoint of A more preferred range is 30 to 100% by weight, and a more preferred range is 50 to 100% by weight.

  The net of the present invention preferably uses a mesh shape such as rhombus, turtle shell, square, zigzag, hexagon. By adopting the above-described mesh shape, a normally used net making machine can be used, and it is possible to suppress an increase in cost during the net making.

  As the network type, it is preferable to use a knotted net, a knotless network, a Russell network, a knotted net, a woven net, etc., and among them, it is better to use a network type that does not form a knot. Is preferable because it is difficult to break the net.

  The mesh is preferably 5 to 200 mm, preferably 10 to 150 mm, and more preferably 15 to 100 mm. When the mesh is less than 5 mm, there is a problem that clogging occurs, and there is a problem that the cost becomes high due to a fine network structure. When the mesh exceeds 200 mm, it is difficult to capture a desired object. .

  The net of the present invention is a safety net, curing net, falling rock prevention net, snow prevention net, slope protection net, sports net, revetment net, vegetation net, fishing net, young tree protection net, etc. It can be used for any purpose such as marine products, forestry, and construction.

  In addition, the net of the present invention may be coated with various resins, films, etc., or may be multi-layered or laminated with nonwoven fabrics, films, or the like.

  Next, the net manufacturing method of the present invention will be described by taking a knotless network as an example. However, the present invention is not limited to the following method as long as the effects of the present invention are not impaired.

  A plurality of polylactic acid fibers which are multifilaments and / or monofilaments are aligned to obtain a fineness required for a net yarn. At this time, the fineness of the net yarn is not particularly limited, and may be appropriately changed according to the application. While the twisted yarn is made into a lower twisted yarn by applying a lower twist, combining two lower twisted yarns, applying an intermediate twist, twisting two intermediate twisted yarns together and applying an upper twist, It is possible to adopt a method of forming a knot portion by combining mesh yarns and simultaneously forming a knotless net by a knotless knitting netting machine that forms a mesh, or a method of knitting using a Russell knitting machine.

  The obtained net is preferably subjected to a heat treatment within a range of 60 to 160 ° C. by a tenter or the like. If the heat treatment temperature is 160 ° C. or lower, a good-quality net can be obtained without causing fusion between polylactic acid fibers, and if it is 60 ° C. or higher, the desired heat setting effect can be obtained. The range of the preferable heat setting temperature is 80 to 150 ° C, more preferably 100 to 140 ° C. The heat setting may be performed when twisting the yarn before netting.

  The tension applied to the net at the time of heat setting can be exemplified by 0.05 to 2 cN / dtex as a preferable range, but is not particularly limited, and an optimal tension may be appropriately applied depending on the application. As a method for measuring the tension, for example, there is a method of monitoring using Tension Pickup (BTB1-R03) manufactured by Eiko Sokki Co., Ltd. and Tension Meter (HS-3060) manufactured by Eiko Sokki Co., Ltd. as a detector.

  Thus, the net of the present invention can be obtained.

  Hereinafter, the present invention will be described in detail with reference to examples. In addition, the measuring method in an Example used the following method.

  [Weight average molecular weight of polylactic acid]: Tetrahydrofuran was mixed with the sample chloroform solution to obtain a measurement solution. This was measured by gel permeation chromatography (GPC-150C, manufactured by Waters Co., Ltd.), and the weight average molecular weight Mw and number average molecular weight Mn as well as the degree of dispersion Mw / Mn were determined in terms of polystyrene.

  [Carboxyl group end concentration]: A precisely weighed sample (1 g) was immersed in 20 ml of o-cresol (5% moisture), dissolved at 145 ° C. for 10 minutes, and titrated with a 0.02 N KOH methanol solution. Asked. At this time, an oligomer such as lactide, which is a cyclic dimer of lactic acid, is hydrolyzed to generate a carboxyl group terminal, so that all of the carboxyl group terminal of the polymer, the monomer-derived carboxyl group terminal, and the oligomer-derived carboxyl group terminal are totaled. The carboxyl group terminal concentration obtained is obtained.

  [Melting point]: Using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer Co., Ltd., a temperature at which an extreme value of a melting endothermic curve obtained by measuring 20 mg of a sample at a heating rate of 5 ° C./min is expressed as a melting point (° C. ).

  [Total Fineness and Filament Fineness]: JIS L1013 8.3.1 Positive Fineness a) According to the A method, the predetermined load is 5 mN / tex × the number of displayed texes, and the predetermined yarn length is 180 m in Example 1, Example In 2-6 and Comparative Examples 1 and 2, it measured at 90 m.

  [Single fiber fineness]: JIS L1013 8.3.1 Positive amount fineness a) According to A method, 5 mN / tex × display tex number as a predetermined load, 180 m in Example 1 as a predetermined yarn length, Examples 2 to 6 In Comparative Examples 1 and 2, a value obtained by dividing the fineness measured at 90 m by the number of single fibers constituting the polylactic acid fiber was adopted.

  [Fiber strength and elongation]: A sample was measured with a “TENSILON” UCT-100 manufactured by Orientec Co., Ltd. under the constant speed elongation condition shown in the JIS L1013 8.5.1 standard time test. At this time, the grip interval was 25 cm, the pulling speed was 30 cm / min, and the number of tests was 10 times. The elongation at break was determined from the elongation at the point showing the maximum strength in the SS curve.

[Boiling water shrinkage ratio]: The sample was immersed in boiling water for 15 minutes, and the dimensional change before and after the immersion was determined by the following equation.
Boiling water shrinkage (%) = [(L0−L1) / L0] × 100
L0: A skein length measured by scraping a sample and measuring it under an initial load of 0.088 cN / dtex.
L1: A skein length measured under an initial load of 0.088 cN / dtex after treatment with boiling water in a load-free state and air drying.

[Spinning property]: Evaluated in two stages from the state of occurrence of yarn breakage and fluff when continuous spinning was performed.
○: Very good and stable yarn production for a long time is possible. Fluff incidence is less than 1 / 10,000m.
Δ: Some fluff is generated but can be used depending on the application. Fluff occurrence rate is 1-2 pieces / 10,000m.
X: Unstable. Fluff occurrence rate is 2 pieces / 10,000m or more.

[Strength retention]: As an acceleration test for hydrolysis resistance, 10 g of the weighed net was fixed so as not to shrink (fixed to a metal frame), and placed in a sealable container together with 3000 ml of water, and then the temperature rising rate was 4 ° C. After heating the container so that the water temperature in the container becomes 130 ° C., hold it at that temperature for 40 minutes, and subsequently cool it at a rate of temperature decrease of 4 ° C./minute. It took out, washed with water, and the strength retention before and after the heat treatment was calculated by the following formula.
Strength retention (%) = T0 / T1 × 100
T1: Tensile strength before heat treatment T0: Tensile strength after heat treatment

  [Matching]: When a sample cut to 50 cm square is kept vertical and an initial load equivalent to 0.8826 cN / dtex is applied, the length from the center of one node to the center of the next node is Measured and determined by doubling the value. In addition, the average value of the measurement about 10 nodes was employ | adopted.

  [Degree of confounding (CF value)] A 100 g load was applied to a sample having a length of 1 m, a 6 g hook was lowered at a descending speed of 1 to 2 cm / sec, and the formula: degree of confounding (CF value) = 100 (cm) / It calculated and calculated | required by descent | fall distance (cm). An average value of 10 trials was adopted.

[Production Example 1] (Production of polylactic acid (PLLA) resin)
Polymerization of lactide produced from L-lactic acid with an optical purity of 99.5% in the presence of bis (2-ethylhexanoate) tin catalyst (lactide to catalyst molar ratio = 10000: 1) at 180 ° C. for 230 minutes in a nitrogen atmosphere. The resin P1 was obtained. The resulting polylactic acid had a weight average molecular weight of 221,000.

[Production Example 2] (Production of polylactic acid resin containing 10% by weight of DAMGIC)
After drying the resin P1 and diallyl monoglycidyl isocyanuric acid (hereinafter referred to as DAMGIC) manufactured by Shikoku Kasei Co., Ltd., the resin P1 is supplied to a twin-screw kneading extruder so as to have a ratio of DAMGIC = 90: 10 (weight ratio). The resin P2 was obtained by kneading at a cylinder temperature of 200 ° C.

[Production Example 3] (Production of polylactic acid resin containing 10% by weight of MADGIC)
Resin P1 and monoallyl diglycidyl isocyanuric acid (hereinafter referred to as MADGIC) manufactured by Shikoku Kasei Co., Ltd. are dried and then supplied to a twin-screw kneading extruder so that the resin P1: MADGIC = 90: 10 (weight ratio). And kneading at a cylinder temperature of 200 ° C. to obtain a resin P3.

[Production Example 4] (Production of polylactic acid resin containing 10% by weight of TGIC)
The resin P1 and triglycidyl isocyanuric acid (hereinafter referred to as TGIC) manufactured by Nissan Chemical Industries, Ltd. are dried, and then supplied to a twin-screw kneading extruder so that the resin P1: TGIC = 90: 10 (weight ratio). The resin P4 was obtained by kneading at a cylinder temperature of 200 ° C.

[Production Example 5] (Production of polylactic acid resin containing 10% by weight of polycarbodiimide)
After drying the resin P1 and the polycarbodiimide “Carbodilite” HMV-8CA (hereinafter referred to as PCI) manufactured by Nisshinbo Co., Ltd., the resin P1: PCI = 90: 10 (weight ratio) was placed in a twin-screw kneading extruder. Then, the mixture was kneaded at a cylinder temperature of 200 ° C. to obtain a resin P5.

Example 1
Resin P1 and Resin P4 were dried at 105 ° C. for 12 hours using a vacuum dryer. Resin P1: Resin P4 was blended in a chip state so as to be 9: 1 (final TGIC concentration 1% by weight) and supplied to a spinning hopper. The blended chips were melt-spun at 220 ° C. using a spinning machine with a twin screw extruder. The polymer melted by the extruder is guided to a spinning pack, filtered through a 20 μm metal nonwoven fabric filter, weighed with a gear pump so as to have the fineness shown in Table 1, and spun from a 96-hole base with a hole diameter of 0.6φ. I put it out.

  A 15 cm heating cylinder and a 15 cm heat insulation cylinder were attached 3 cm below the base surface, and heated so that the in-cylinder atmosphere temperature was 250 ° C. Here, the in-cylinder atmosphere temperature is an air layer temperature in a central portion of the heating cylinder length and a portion 1 cm away from the inner wall.

  An annular blow-off chimney was attached directly under the heating cylinder, and cold air at 30 ° C. was blown onto the yarn at a rate of 30 m / min to cool and solidify, and then an oil agent was applied to the yarn. As the oil, TRN-4627 manufactured by Takemoto Yushi Co., Ltd. was used as an 18% emulsion using ion-exchanged water.

The unstretched yarn provided with the oil agent was wound around 1 FR rotating at a surface speed of 375 m / min. Next, the take-up yarn was continuously wound without being wound once and stretched 1.5% between the take-up roller and 2FR, and subsequently subjected to three-stage heat stretching to obtain 1.5% After giving relaxation, it was wound up at a speed of 3000 m / min. Direct spinning drawing was performed using the process shown in FIG. 1FR was 60 ° C, 2FR was 100 ° C, 1DR was 115 ° C, 2DR was 140 ° C, 3DR was 140 ° C, and RR was not heated. The number of times the yarn was wound around the roller was 3, 4, 4, 4, 5, and 4, respectively. An entanglement nozzle was installed between the RR and the winder to entangle the fibers. Entangling was performed by injecting ² kg / cm ² of high-pressure air in a direction substantially perpendicular to the running yarn in the entanglement imparting device to obtain polylactic acid fibers. The obtained fiber properties were evaluated and shown in Table 1. The first stage draw ratio was 34% of the overall draw ratio, the second stage draw ratio was 33%, and the third stage draw ratio was set to 33%.

  The obtained polylactic acid fiber was knitted with a front of 7,000 dtex and a back of 4,700 dtex using a Russell knitting machine, and a net having a mesh size of 25 mm was produced. The characteristics of the obtained net were evaluated, and the results are shown in Table 1.

(Example 2)
A polylactic acid fiber was produced in the same manner as in Example 1 except that the resin P3 was used instead of the resin P4, and the properties of the net obtained by producing the net were evaluated. The results are shown in Table 1.

(Example 3)
The resin P2 is used instead of the resin P4, the resin P1 and the resin P2 are blended so that the final concentration of DAMGIC is 0.4% by weight, and the base described in Example 1 of JP-A-2005-240219 That is, in the same manner as in Example 1 except that a polylactic acid fiber having a hollow ratio of 40% was obtained using a die having a slit width of 0.35 mm, a slit diameter of 1.8 mm, and 48 holes with 4 slits. The properties of the net obtained by producing the polylactic acid fiber and producing the net were evaluated, and the results are shown in Table 1.

Example 4
The resin P2 is used instead of the resin P4, the resin P1 and the resin P2 are blended so that the final concentration of DAMGIC is 7% by weight, and the yarn is entangled in the entanglement imparting device so that the entanglement degree shown in Table 1 is obtained. A polylactic acid fiber was produced in the same manner as in Example 1 except that the pressure of the high-pressure air ejected on the strip was changed, and the properties of the net obtained by producing the net were evaluated. The results are shown in Table 1. .

(Example 5 and Example 6)
A polylactic acid fiber can be produced and a net can be produced in the same manner as in Example 1 except that the pressure of the high-pressure air ejected onto the yarn in the entanglement imparting device is changed so as to achieve the entanglement degree shown in Table 1. The characteristics of the obtained net were evaluated, and the results are shown in Table 1.

(Comparative Example 1)
Polylactic acid fibers were produced in the same manner as in Example 1 except that the resin P5 was used instead of the resin P4, and the properties of the net obtained by producing the net were evaluated. The results are shown in Table 1.

(Comparative Example 2)
Polylactic acid fibers were produced in the same manner as in Example 1 except that only the resin P1 was used, and the properties of the net obtained by producing the net were evaluated. The results are shown in Table 1.

  As is clear from Table 1, the nets of the present invention described in Examples 1 to 6 are much more resistant to hydrolysis than the polylactic acid of Comparative Example 2 in which the carboxyl terminal of the polylactic acid fiber is not blocked. It was an excellent net. In addition, the present invention does not impair the effect even if it is a modified cross-section fiber as in Example 3, and it is lightweight and can add added value such as reducing the burden on the operator when installing the net. It was.

  On the other hand, when the carboxyl terminus of polylactic acid is blocked using a compound other than the general formula (I) disclosed in the present invention as described in Comparative Example 1, it results from poor reactivity between polylactic acid and the compound. As a result, there was a problem that not only the poor spinning performance but also a bad odor occurred during spinning, which deteriorated the working environment.

It is a spinning process figure of an example of an embodiment of the present invention.

Explanation of symbols

1: Hopper 2: Extruder 3: Spin pack 4: Spinneret 5: Slow cooling zone 6: Cooling device 7: Refueling device 8: 1 FR
9: 2FR
10: 1DR
11: 2DR
12: 3DR
13: RR
14: Entangling device 15: Winding device

Claims (5)

A net characterized in that a polylactic acid fiber represented by the following general formula (I), wherein a part or all of the carboxyl terminal is blocked with at least one compound, is at least part of the constituent elements.

(Here, at least one of R _{1 to} R ₃ is a glycidyl group, and the remainder represents a group selected from hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, and an allyl group.)   The net according to claim 1, wherein the amount of carboxyl terminals of the polylactic acid fiber is 20 equivalent / t or less.   The net according to claim 1 or 2, wherein the addition amount of the compound represented by the general formula (I) is 0.1 to 5% by weight of the whole polylactic acid fiber.   The compound represented by the general formula (I) is one or more selected from diallyl monoglycidyl isocyanurate, monoallyl diglycidyl isocyanurate, and triglycidyl isocyanurate. Net described in.   The net according to any one of claims 1 to 4, wherein the polylactic acid fiber has an entanglement degree of 5 to 70.

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