JP2005113343A - Net - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new net having an excellent durability and biodegradability and consisting of a polylactic acid fiber having biodegradability and high strength, and excellent in mechanical properties such as abrasion resistance, etc. <P>SOLUTION: This net consists of the polylactic acid fiber having 250-4,000 dtex fiber fineness, 4.5-7.0 cN/dtex strength and 15-40 % elongation, and containing 0.1-5 wt. % fatty acid bisamide and/or alkyl-substituted type fatty acid monoamide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a net using polylactic acid fibers. More specifically, the present invention relates to a novel net having excellent durability and biodegradability using a polylactic acid fiber having biodegradability, high strength, and excellent mechanical properties such as wear resistance.

  Since polylactic acid fibers are fibers that are biodegradable and obtained from non-petroleum-based raw materials, they have attracted attention in recent years as fibers having a small environmental load even when discarded, and their application development has been promoted. For example, drained garbage bags, seedling mats, herbicidal sheets for vegetation, tea bags, towels, gloves, napkins, etc. are applications that make use of the characteristics of polylactic acid fibers that are mainly biodegradable and made of non-petroleum materials. In addition, polylactic acid fiber has a unique luster, good color development when dyed, and has a smooth touch and texture, making use of its fashionability, blouse, shirt, scarf, handkerchief, lining Development is progressing for use. Furthermore, it is being put to practical use in interior applications such as car option mats, household roll carpets and rugs.

  On the other hand, for industrial materials, after using polylactic acid fiber as a product, many uses have been proposed by taking advantage of the biodegradable feature that the load at the time of disposal is low. The successes are still limited. Industrial materials applications such as building construction nets, building construction sheets, land nets, sandbag bags, tents, tarpaulins, etc. are particularly required for high strength, high toughness, wear resistance, etc. and are used as products. In the actual situation, the conventional polylactic acid fiber is too risky to guarantee safety because it is required to be durable.

  In order to be able to be applied to industrial materials with peace of mind, it has the mechanical properties and durability of the polyester fiber level with a proven track record, and the properties are maintained for a certain period of time, after which the properties are no longer necessary. From the point of view, fibers that are biodegradable are ideal. Conventional polylactic acid fibers have a problem that the mechanical properties such as strength and wear resistance are slightly inferior to the required properties, and the durability is insufficient.

  Nets, which are one of industrial material applications, have been used by knitting polyethylene terephthalate, polyethylene and polypropylene fibers. However, since the nets made of these non-biodegradable fibers are not particularly recoverable, they have a problem of being abandoned in the natural environment after use and accumulated without being decomposed. However, polylactic acid fibers developed in recent years are made of non-petroleum raw material biodegradable polymers, and improved mechanical properties and polymer cost reduction are progressing. Yes.

  Regarding the technology used as a net, Patent Literature 1, Patent Literature 2 and Patent Literature 3 are disclosed. Patent Document 4 and Patent Document 5 are disclosed for polylactic acid to which a fatty acid amide is added.

  Patent Document 1 aims to “solve problems in conventional safety nets and provide a safety net having excellent weather resistance and biodegradability.” The problem is “the melting point is 130 ° C. or higher. It is said to be achieved by a “safety net characterized by comprising fibers mainly composed of aliphatic polyester”. However, there is no description in the prior art about the improvement of the abrasion resistance of the polylactic acid fiber and the polylactic acid fiber containing a fatty acid amide compound for achieving the improvement.

  Patent Document 2 has an object of “providing a net excellent in weather resistance and impact resistance”, and the problem is “mainly an aliphatic polyester having a melting point of 130 ° C. or more and having a single fiber fineness of 3.0 dtex or less. A net comprising fibers, wherein the dynamic friction coefficient of the fiber is 0.1 or less, the fiber strength is 5.0 cN / dtex or more, the elongation is 15 to 40%, and the mesh of the net is 5 to 5 It is 200 mm, and is achieved by a net characterized in that organosilicon, organic fluorine, polymer wax, and the like are applied to the fiber surface. The prior art disclosed that “polylactic acid fiber having excellent weather resistance is used, and that impact resistance is such that the single yarn fineness of the fiber is 3 dtex or less, and organosilicon, organic fluorine and polymer wax are formed on the fiber surface. Etc. ”is the main content.

  Patent Document 3 has an object of “providing a construction net that can maintain strength even when exposed to the outdoors for a long period of time”, and the subject is “strong maintenance after irradiation for 500 hours of weathering test sunshine weatherometer” It is a construction work net knitted using synthetic fibers with a fineness of 80% or more and 3,300 dtex or less. The prior art discloses that a construction net using polylactic acid fibers having excellent weather resistance and having a specific fineness or less is used. However, there is no mention of the use of polylactic acid fibers having excellent wear resistance, and the use of polylactic acid fibers containing a fatty acid amide compound for the net, and the like. It is clear that it is completely different.

Patent Document 4 has an object of “providing a novel polymer composition having lactic acid as a main component and having suppressed degradability”, and the subject is “a polylactic acid polymer having lactic acid as a main component”. (1) paraffin having a molecular weight of 150 or more, (2) polyethylene having a molecular weight of 50,000 or less, (3) modified polyethylene having a molecular weight of 50,000 or less, and (4) the number of carbon atoms in one molecule (hereinafter referred to as carbon number). An abbreviation) having 10 or more aliphatic alcohols, (5) aliphatic carboxylic acids having 10 or more carbon atoms and their metal salts, (6) amides of aliphatic carboxylic acids having 10 or more carbon atoms, (7) having 10 or more carbon atoms A polylactic acid composition obtained by mixing 0.1 to 4% by weight of at least one compound selected from the group consisting of esters of aliphatic carboxylic acids of (8) and esters of aliphatic alcohols having 10 or more carbon atoms. It is said that it can be solved by. The prior art relates to a polylactic acid fiber containing a fatty acid amide, and is intended to control the rate of biodegradation according to the application and the environment in which it is used, and at least one of the eight types of compounds specified. It is said that this can be achieved by forming a composition obtained by mixing seeds with polylactic acid and a molded product thereof. One type ((6)) describes “aliphatic carboxylic acid amides having 10 or more carbon atoms”. However, the fatty acid amide in Patent Document 4 is substantially a fatty acid monoamide, and when a fatty acid monoamide is used, the monoamide is highly reactive, so it reacts with polylactic acid at the time of melting and remains a monoamide compound. The proportion remaining in the fiber is reduced, and the net does not have high strength and improved mechanical properties such as wear resistance and durability. In addition, the reaction may reduce the molecular weight of polylactic acid, resulting in a decrease in fiber properties, particularly strength. In addition, fatty acid monoamides have high sublimation properties, and as a sublimation product during spinning, they adhere to the equipment wall and deteriorate workability, and aggregated sublimation products adhere to fibers and cause thread breakage and dirt. May occur. Patent Document 5 has the subject “To make an aliphatic polyester molded article exhibit transparency and crystallinity at the same time.” The subject is “aliphatic polyester and aliphatic carboxylic acid amide, aliphatic carboxylate, Forming an aliphatic polyester composition containing at least one transparent nucleating agent selected from a group of compounds having a melting point of 40 to 300 ° C. comprising an aliphatic alcohol and an aliphatic carboxylic acid ester, and crystallizing at the time of molding or after molding It is said that it can be solved by “A method for producing an aliphatic polyester molded article having both transparency and crystallinity”. The prior art is a technique in which polylactic acid contains an aliphatic carboxylic acid amide as a crystallization nucleating agent in order to simultaneously exhibit transparency and crystallinity of an aliphatic polyester molded article. This technique is used as a compound that becomes a crystallizing agent that simultaneously satisfies the transparency and crystallinity of an aliphatic polyester molded product such as polylactic acid, as an aliphatic carboxylic acid amide, an aliphatic carboxylate, an aliphatic alcohol, and an aliphatic carboxylic acid. It is said that it is effective to contain at least one compound group consisting of acid esters having a melting point of 40 to 300 ° C.
JP 2000-226757 A JP 2000-234251 A JP 2001-303411 A JP-A-8-183898 JP-A-9-278991

  An object of the present invention is to overcome the above-described problems and provide a net made of a novel polylactic acid fiber that cannot be achieved by the prior art. That is, it is to provide a novel net having excellent durability and biodegradability using a polylactic acid fiber having biodegradability, high strength and excellent mechanical properties such as wear resistance. .

The object of the present invention can be achieved by the following means.
1. A net comprising polylactic acid fiber containing 0.1 to 5% by weight of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide with respect to the whole fiber.
2. 2. The net according to item 1, wherein the polylactic acid fiber has a fineness of 250 to 5,000 dtex, a strength of 4.5 to 7.0 cN / dtex, and an elongation of 15 to 40%.
3. 3. The net according to item 1 or 2, wherein the polylactic acid fiber is an original yarn.
4). Item 4. The net according to any one of items 1 to 3, wherein the mesh is 5 to 200 mm.
5. The net according to any one of items 1 to 4, which is a safety net, a curing net, a rockfall prevention net, a snow net, a slope protection net, a revetment net, a sports net, or a fishing net. A net characterized by being one kind.

  According to the present invention, a novel net having excellent durability and biodegradability is provided by using polylactic acid fibers having biodegradability, high strength, and excellent mechanical properties such as wear resistance. can do.

  Hereinafter, the present invention will be described in detail.

  The net of the present invention is a knitted net used for a safety net, a curing net, a rockfall prevention net, a snow prevention net, a slope protection net, a revetment net, a sports net, a fishing net, etc. Part of the net is a net made of polylactic acid fiber that has biodegradability, high strength, and excellent mechanical properties such as wear resistance.

  The polylactic acid polymer used as the raw material for the polylactic acid fiber used in the net of the present invention is a polymer obtained by polymerizing an oligomer of lactic acid such as lactic acid or lactide, and the optical purity of L-form or D-form of lactic acid in the polymer is 90% or more. It is preferable that the melting point is high. The optical purity of the L-form or D-form is more preferably 97% or more. A blend of polylactic acid having an optical purity of 90% or higher in the L form and polylactic acid having an optical purity of 90% or higher in the D form at a ratio of 70/30 to 30/70 is preferable because the melting point is further improved. When the molecular weight of the polylactic acid polymer is 50,000 to 500,000 in terms of weight average molecular weight, it is preferable that the balance between mechanical properties and moldability is good. In addition, components other than lactic acid may be copolymerized as long as the properties of polylactic acid are not impaired. Polymers and particles other than polylactic acid, matting agents, plasticizers, flame retardants, antistatic agents, Additives such as odorants, antibacterial agents, antioxidants, heat resistance agents, light resistance agents, ultraviolet absorbers, and coloring pigments may be included as necessary. As a polymer other than polylactic acid, for example, an aliphatic polyester polymer such as polycaprolactone, polybutylene succinate, and polyethylene succinate can be used as a plasticizer. However, the polylactic acid fiber according to the present invention is a biodegradable and non-petroleum-based raw material, and is used as a product with a small environmental impact even when discarded. It is more preferable that various additives are not used at all such as heavy metal compounds and environmental hormone substances, and compounds that are expected to be concerned at present.

  The polylactic acid fiber in the present invention has a higher strength than conventional ones, and is particularly characterized in that the wear resistance is remarkably improved. This excellent property is achieved by incorporating at least one of fatty acid bisamide and alkyl-substituted fatty acid monoamide into the polylactic acid fiber in the present invention.

  The fatty acid bisamide in the present invention 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 acid amide, methylene biscapric acid amide. , Methylene bis 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 biscaprylic amide, ethylene biscapric amide, ethylene bislauric acid amide, ethylene bismyristic acid amide, ethylene bispalmitic acid amide, ethylene bisstearic acid amide, ethylene bis Sostearic 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 bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bis oleic acid amide, hexamethylene bis erucic acid amide, m-xylylene bis stearic acid amide, m-xylylene bis-12-hydroxy stearic 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'-dioleyl adipic acid amide, N, N'-dioleyl sebacic acid amide, N, N'-distearyl isophthalic acid amide, N, N'-distearyl terephthalic acid amide, methylenebishydroxystearic acid amide, ethylene Examples thereof include bishydroxystearic acid amide, butylene bishydroxystearic acid amide, and hexamethylene bishydroxystearic acid amide.

  The alkyl-substituted fatty acid monoamide referred to in the present invention refers to a compound having a structure in which an amide hydrogen such as a saturated fatty acid monoamide or an unsaturated fatty acid monoamide is replaced with an alkyl group, such as 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-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl And 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.

  In the present invention, fatty acid bisamides and alkyl-substituted fatty acid monoamides are used, but these compounds have lower amide reactivity than ordinary fatty acid monoamides, and are less likely to react with polylactic acid during melt molding. In addition, since many of them have a high molecular weight, they generally have good heat resistance and are difficult to sublimate. In particular, fatty acid bisamides can be more preferably used because they are less reactive with polylactic acid due to the lower reactivity of amides, and are high in heat resistance and difficult to sublime due to their high molecular weight.

  In the polylactic acid fiber of the present invention, it is important to contain 0.1 to 5% by weight of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide with respect to the whole fiber. Preferably it is 0.5 to 3 weight%. If the amount is less than 0.1% by weight, the effect of the present invention cannot be sufficiently obtained. On the other hand, if it exceeds 5% by weight, the strength of the polylactic acid fiber is lowered and the production yield is lowered. By making the content of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide in the above range, the slipperiness of the fiber surface is improved, and the strength and abrasion resistance required for the net and durability in repeated use are given. can do. 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. Even when mixed and used, the entire mixture may be contained in an amount of 0.1 to 5% by weight.

  Further, the polylactic acid fiber in the present invention is preferably provided with an oil containing a smoothing agent as a main component and containing a surfactant, an antistatic agent, an extreme pressure agent component, and the like. A preferred oil agent composition is, for example, a non-aqueous oil agent obtained by diluting an alkyl ether ester as a smoothing agent, an alkylene oxide adduct of a higher alcohol as a surfactant, and an organic phosphate salt as an extreme pressure agent with mineral oil. By applying the oil agent, the surface friction coefficient of the polylactic acid fiber is reduced, and the wear resistance of the net can be further improved.

  The polylactic acid fiber used in the net of the present invention preferably has a fineness of 250 to 5,000 dtex, a strength of 4.5 to 7.0 cN / dtex, and an elongation of 15 to 40%. Even if the fineness is less than 250 dtex and exceeds 5,000 dtex, the basic performance of the net of the present invention is maintained, but in order to increase the production efficiency and supply at a low cost, the fineness of less than 250 dtex is disadvantageous, , Fibers exceeding 5,000 dtex are difficult to handle and the fineness range is preferred. If the strength is less than 4.5 cN / dtex, the strength as a net is slightly reduced, and polylactic acid fibers exceeding 7.0 cN / dtex are difficult to industrially produce with the current technology. The elongation is an elongation that is manifested when the strength in the present invention is achieved. For example, if it is less than 15%, excellent wear resistance cannot be obtained, and if the elongation exceeds 40%, a high strength is obtained. It becomes impossible.

  The polylactic acid fiber in the present invention is preferably an original yarn. This is because the polylactic acid fiber for the net is required to have a high strength, and therefore a strength reduction in the dyeing process is avoided. The colorant added to the polylactic acid original yarn in the present invention is a specific inorganic, organic pigment and dye suitable for polylactic acid fibers. Specifically, oxide-based inorganic pigments excluding lead, chromium and cadmium, ferrocyanide inorganic pigments, silicate inorganic pigments, carbonate inorganic pigments, phosphate inorganic pigments, carbon black, aluminum powder, bronze powder and titanium powder Selected from inorganic pigments such as coated mica, organic pigments such as phthalocyanine organic pigments, perylene organic pigments, isointoserinone organic pigments, and heterocyclic dyes, helinone dyes, perylene dyes and thioindio dyes Or a combination of two or more. For example, inorganic pigments include oxides such as titanium oxide, zinc white, titanium yellow, zinc-iron-based brown, titanium-cobalt green, cobalt green, cobalt blue, copper-iron black, and ferrocyans such as bitumen. , Silicates such as county blue, carbonates such as calcium carbonate, phosphates such as manganese violet, carbon black, aluminum powder and bronze powder, and titanium powder-coated mica are used, lead, chromium and cadmium Inorganic pigments containing heavy metals such as are not used. As the organic pigment, phthalocyanine series such as copper phthalocyanine blue, copper phthalocyanine green and brominated copper phthalocyanine green, perylene series such as perylene scarlet, perylene la, perylene maroon, isoindolinone, etc. are used. Examples of the dye include anthraquinone series such as Solvent R.50, Solvent R.111, Solvent B.94, Solvent V.50, Solvent G.3, and heterocyclic systems such as Solvent Y.33 and Solvent Y. .111, Solvent Y.54, Helinone series such as Solvent O.60, Solvent R.135, Solvent R.179, perylene series such as Solvent G.5, thioindio series such as Vat R.1 are used.

  The colorant used for the polylactic acid original yarn in the present invention is used in combination of one or more selected from the above inorganic pigments, organic pigments and dyes. Preferably, the colorant is adjusted by using two or more kinds. By using a combination of two or more colorants, it is possible to produce a subtle color tone that can be compared to conventional dyed polylactic acid fibers.

  The addition concentration of the colorant varies depending on the type of the dye, but is 100 to 30,000 ppm, preferably 500 to 10,000 ppm as the total amount of the colorant per polymer weight. The colorant can also be used in combination with a commonly used dispersant.

  Further, when the net of the present invention is used for construction nets such as safety nets and curing nets, the bifunctional phosphorus compound is added in an amount of 0.1 to 1.5% by weight in order to impart flame retardancy as necessary. It is preferable to contain. Specifically, the bifunctional phosphorus compound contained in the polylactic acid fiber used in the net of the present invention preferably has a structure represented by the following chemical formulas (I) to (III).

（式（Ｉ）〜（III）中、Ｒ₁、Ｒ₅は同じか又は異なる基であって、炭素数１〜１８の炭化水素を表し、Ｒ₂、Ｒ₃はそれぞれ同じか又は異なる基であって、炭素数１〜１８の炭化水素基又は水素原子を表し、Ａ₁は２価の有機基、Ａ₃は３価の有機残基を表し、Ｒ₄はカルボキシル基またはそのエステルを表し、Ｒ₆はカルボキシル基又はそのエステルあるいは互いに下記（IV）で示される基を介してＡ₂と環を形成する２価のエステル形成性官能基を表す。）

(In the formulas (I) to (III), R ₁ and R ₅ are the same or different groups and represent hydrocarbons having 1 to 18 carbon atoms, and R ₂ and R ₃ are the same or different groups, respectively. And represents a hydrocarbon group having 1 to 18 carbon atoms or a hydrogen atom, A ₁ represents a divalent organic group, A ₃ represents a trivalent organic residue, R ₄ represents a carboxyl group or an ester thereof, R ₆ represents a carboxyl group or an ester thereof or a divalent ester-forming functional group that forms a ring with A ₂ through a group represented by the following (IV).

前記の式（Ｉ）におけるリン化合物の好ましい具体例としては、フェニルホスホン酸ジメチル、フェニルホスホン酸ジフェニル等である。

Preferable specific examples of the phosphorus compound in the above formula (I) include dimethyl phenylphosphonate, diphenyl phenylphosphonate and the like.

  Preferable specific examples of the phosphorus compound in the formula (II) include (2-carboxyethyl) methylsulfinic acid, (2-carboxyethyl) phenylphosphinic acid, (2-methoxycarboxyethyl) phenylphosphinic acid methyl, (4 -Methoxycarbonylphenyl) phenylphosphinic acid methyl, ethylene glycol ester of (2- (β-hydroxyethoxycarbonyl) ethyl) methylphosphinic acid, and the like.

  Preferable specific examples of the phosphorus compound in the formula (III) include (1,2-dicarboxyethyl) phosphine oxide, (2,3-dicarboxypropyl) dimethylphosphine oxide, (2,3-dimethoxycarbonylethyl). Examples include dimethylphosphine oxide and (1,2-di (β-hydroxyethoxycarbonyl)) dimethylphosphine oxide.

  Among the compounds represented by the formulas (I) to (III), the phosphorus compound (II) is particularly preferably used because it has good copolymerizability with the polyester and less scattering during the polycondensation reaction.

  The amount of the bifunctional phosphorus compound added is preferably 0.1 to 1.5% by weight. This is because, by setting the addition amount in such a range, the flame retardancy effect is sufficient, while the mechanical properties and weather resistance of the fiber can be maintained.

  Next, the net of the present invention is preferably used as a woven net such as a safety net, a curing net, a rockfall prevention net, a snow prevention net, a slope protection net, a revetment suction prevention net, a sports net, a fishing net, etc. Can do. The net of the present invention is designed with a knitted net depending on the application, but the mesh is preferably 5 to 200 mm. Although it can be used for a net having a mesh size of less than 5 mm or exceeding 200 mm, the above-mentioned mesh size is applied to the use of the net of the present invention.

  As described above, the net of the present invention has durability when repeatedly used as the above net, while on the other hand, it remains buried in the soil after a certain period of use or is recovered and composted. By doing so, it is biodegraded and eventually disappears, so it is useful as a net with less environmental load.

  A preferred example of the method for producing the polylactic acid fiber in the present invention is shown below.

  The polylactic acid in the present invention can be synthesized using a known method, but it is preferable that the polylactic acid itself has a good color tone and that residual oligomers and monomers such as lactide are reduced. As a specific method, for example, as described in JP-A-7-504939, it is preferable to use a metal deactivator, an antioxidant, or the like, to lower the polymerization temperature, and to suppress the catalyst addition rate. Moreover, the amount of residual oligomers and monomers can be greatly reduced by subjecting the polymer to reduced pressure treatment or extraction with chloroform or the like.

  The polylactic acid used for producing the polylactic acid fiber in the present invention uses a high viscosity polymer having a relative viscosity of 2.5 to 5. Preferably, it is the range of 3.5-4.5. When a polymer having a relative viscosity of less than 2.5 is used, it may not be possible to stably obtain a polylactic acid fiber having high strength and excellent wear resistance according to the present invention. On the other hand, when a high-viscosity polymer having a relative viscosity exceeding 5 is used, it is difficult to produce a stable yarn or film, and polylactic acid fibers having excellent uniformity may not be obtained.

  The method for incorporating the fatty acid bisamide and / or the alkyl-substituted fatty acid monoamide into the polylactic acid fiber in the present invention is not particularly limited, and examples thereof include the following methods. First, as a kneading step, polylactic acid and fatty acid bisamide and / or alkyl-substituted fatty acid monoamide are dried and then supplied to a nitrogen-sealed kneading extruder to produce a kneading chip. Next, melt spinning or melt extrusion is performed by subjecting the kneading chip to an extruder. In the kneading step, a kneaded chip containing a high ratio of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide is prepared (master chip formation), and when this is used in a spinning machine or an extruder, fatty acid bisamide and / or alkyl-substituted A method of blending and diluting ordinary polylactic acid chips so that the desired fatty acid monoamide content can be used. In the melt spinning or melt extrusion process, it is also possible to knead the polylactic acid and the fatty acid amide more finely by installing a static kneader between the extruder and the pack or in the pack. Aggregation of fatty acid amides and bleed-out to the fiber surface may cause deterioration of operability due to soiling of guides and rollers, and also cause physical and dyeing spots on the fiber product. Therefore, in the kneading process, melt spinning or melt extrusion process, The fatty acid amide is preferably finely dispersed in polylactic acid.

  Further, kneading and melt spinning or melt extrusion may be performed in the same step, and for example, the following method may be used. In the first method, polylactic acid and fatty acid bisamide and / or alkyl-substituted fatty acid monoamide are dried and then supplied to an extruder sealed with nitrogen, and the polylactic acid and fatty acid bisamide and / or alkyl-substituted kneaded by the extruder This is a method in which a kneaded polymer melt of a fatty acid monoamide is further finely kneaded by a static kneader and discharged from a discharge hole to be melt spun or melt extruded. In the second method, polylactic acid and fatty acid bisamide and / or alkyl-substituted fatty acid monoamide are melted separately, the melt is finely kneaded by a static kneader, and discharged from a discharge hole to be melt-spun or melt-extruded. It is a method to do.

  The fatty acid bisamide and / or the alkyl-substituted fatty acid monoamide may be contained in an amount of 0.1 to 5% by weight based on the total amount of the blend polymer. By setting the content of the fatty acid amide to 0.1% by weight or more, the surface friction coefficient of the fiber can be reduced, and the process passability in the knitting process can be improved. In addition, when the content of the fatty acid amide is 5% by weight or less, an excess of the fatty acid amide bleeds out from the molten polymer during kneading, spinning, or extrusion, which causes sublimation or decomposition to cause smoke generation. It is possible to prevent deterioration in operability such as deterioration of the environment and contamination of the extrusion kneader, melt spinning machine, and melt extruder due to excessive fatty acid amide sublimates or decomposition products. Moreover, if the content of the fatty acid amide is 5% by weight or less, in the spinning or extrusion process, the bleed-out of the fatty acid amide from the molten polymer is suppressed, so that the discharge of the polymer from the discharge hole is stabilized, This is preferable because fibers having uniform physical properties can be obtained. The content of the fatty acid amide is preferably 0.5 to 3% by weight. In the present invention, fatty acid bisamides and / or alkyl-substituted fatty acid monoamides are used. However, these are preferable lubricants because they are less likely to sublimate and have better heat resistance than prior art fatty acid monoamides. In particular, fatty acid bisamides can be preferably used because they are less reactive with polylactic acid due to the lower reactivity of amides, and are high in heat resistance and difficult to sublimate due to their high molecular weight.

  When the polylactic acid fiber in the present invention is produced by the melt spinning method, the spinning temperature is 190 to 250 ° C, preferably 200 to 240 ° C. Immediately below the spinneret, the upper end is 0 to 15 cm from the base, and the range from 5 to 100 cm from the upper end is surrounded by a heating tube and / or a heat insulating tube, and the spun yarn passes through a high temperature atmosphere of 200 to 280 ° C. It is preferable to make it. The spinning filament is not cooled immediately, but is gradually cooled through a high-temperature atmosphere surrounded by the heating tube and / or the heat insulating tube, thereby relaxing the orientation of the spun filament and uniformity among the filaments. And a high-strength polylactic acid fiber can be obtained.

  The unstretched filament that has passed through the high-temperature atmosphere is then cooled and solidified by blowing air at 10 to 50 ° C., preferably 15 to 30 ° C. The air cooling device may be a horizontal blowing type or an annular blowing type.

  The unstretched filament that has been cooled and solidified is then applied with an oil agent. The oil agent contains a smoothing agent as a main component and includes a surfactant, an antistatic agent, an extreme pressure agent component, and the like, but it is necessary to have an oil agent composition excluding components active on polylactic acid fibers. A preferred oil agent composition is, for example, a non-aqueous oil agent obtained by diluting an alkyl ether ester as a smoothing agent, an alkylene oxide adduct of a higher alcohol as a surfactant, and an organic phosphate salt as an extreme pressure agent with mineral oil.

  The unstretched filament yarn provided with the oil is wound around a take-up roll (1FR) and taken up. The speed of the take-up roll, that is, the spinning speed is 300 to 3,000 m / min. Although the physical properties of the polylactic acid fiber in the present invention can be obtained even at a spinning speed of less than 300 m / min, it is difficult to employ industrially because the production efficiency is low. On the other hand, when the spinning speed exceeds 3,000 m / min, the high-strength polylactic acid fiber in the present invention cannot be stably obtained.

  The undrawn yarn taken up at the spinning speed is drawn continuously without being wound once. As with the take-up roll (1FR), a Nelson roll having two rolls as one unit is a yarn feeding roll (2FR), a first draw roll (1DR), a second draw roll (2DR), and a third draw roll. (3DR) and the relaxation roll (RR) are arranged side by side, and the yarn is sequentially wound to perform a drawing heat treatment. Usually, between 1FR and 2FR, a stretch of 0.5 to 10%, preferably about 1 to 5% is performed to converge the yarn. 1FR is heated to 50 to 80 ° C., preferably 55 to 70 ° C., and the take-up yarn is preheated and sent to the next drawing step. The first stage of stretching is performed between 1DR and 2DR. At this time, the draw point, that is, the necking point, is positioned on the 1DR roll so that it is stably located within a few centimeters immediately before leaving the roll. And the draw ratio of the 1st step is set. However, these conditions need to be changed in consideration of the degree of orientation of the undrawn yarn. Usually, the temperature of 2FR is 80 to 120 ° C., preferably 90 to 110 ° C., the temperature of 1DR is 90 to 130 ° C., preferably 100 to 120 ° C., and the first stage draw ratio is 10 of the total draw ratio. It is set to ˜70%, preferably 20 to 50%. Within the range of the above conditions, the draw point is set so as to be positioned in the vicinity of the 2FR roll upper exit. Furthermore, in order to set the draw point so as to be positioned at the upper outlet of the 2FR roll, the roll is preferably a satin roll with low friction.

  The second stage stretching is performed between 1DR and 2DR, and 2DR is 110 to 150 ° 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 150 ° C, preferably 125 to 145 ° C. The yarn that has finished the two-stage drawing or the three-stage drawing is subjected to a relaxation treatment of 0.5 to 10%, preferably 1 to 7% with the RR, not only to remove the distortion caused by the hot drawing, but also to the drawing. It is possible to fix the highly oriented structure achieved by the above, or to relax the orientation of the amorphous region and lower the thermal shrinkage rate. RR uses an unheated roll or a roll heated to 150 ° C. or lower. Usually, RR becomes a temperature of 90 to 150 ° C. regardless of the presence or absence of heating due to the heat brought in by the yarn heated at the time of hot drawing.

  Moreover, in the manufacturing method of the polylactic acid fiber in this invention, it is preferable to set it as multistage extending | stretching of 2 to 5 steps, preferably 3 to 5 steps. When the number of drawing stages is one, high-strength fibers are difficult to obtain because it cannot be drawn at a high magnification. Further, when the number of stretching stages is 5 or more, it is not preferable because the equipment is enlarged and the manufacturing process becomes complicated.

  Thus, the polylactic acid fiber in the present invention is obtained.

  Next, the net of the present invention is manufactured using a net making machine, a Russell knitting machine or the like, although the design of the knitting net varies depending on the application. Specifically, there are a method of making a net using a net making machine such as a knotless net or a braided netting machine, and a method of making a knitting net using a chain knitting yarn and an insertion yarn by a Russell knitting machine. The shape of the stitch of the net is not particularly limited, and usually a quadrangle, a hexagon, a rhombus, or the like is used.

  For example, in the case of a safety net, 2 to 6 polylactic acid fibers of 1,100 dtex are combined and subjected to a lower twist, and then 2 to 8 lower twisted yarns are combined and twisted in a direction opposite to the lower twist. To give a twisted yarn. Next, the resultant twisted yarn is knitted with a Russell knitting machine to form a net. The net knitted fabric is used after being heat set. Usually, heat setting is performed at 110 to 130 ° C. for 30 seconds to 3 minutes, preferably 115 to 125 ° C. for 1 to 2 minutes. Thus, a net having a mesh of 5 to 200 mm is obtained.

  Hereinafter, the present invention will be described in detail with reference to examples. The characteristic definitions and measurement methods described in the text and examples are as follows.

A. 25 mL of chloroform was added to a sample having a relative viscosity of 0.5 g, and the mixture was stirred for 5 hours to dissolve the polymer. Then, chloroform was added to dilute to 50 mL. The diluted solution was measured using a Schott AVS500 auto viscometer at a test temperature of 30 ° C., and the relative viscosity ηr was determined based on the following formula.

ηr = t / t ₀
t: number of seconds during which the solution flows
t ₀ : Flowing seconds of solvent (chloroform only) The measurement was performed 3 times, and the average value was taken.

B. Fineness Measured according to JIS L1090.

C. Strength and elongation Measured according to JIS L1013. The strength was measured using a Tensilon tensile tester manufactured by Orientec Corp. under the conditions of a test length of 250 mm and a tensile speed of 300 mm / min. The strength is a value obtained by dividing the strength by the total fineness of the sample.

D. Dry heat shrinkage rate Measured at 120 ° C. according to JIS L1013. Three samples were collected from the same sample and measured, and the average value was obtained.

E. Abrasion Resistance of Net A test piece having a diameter of 120 mm was cut out from the net and attached to a Taber abrasion tester specified in ASTM D1175, and subjected to 1,000 rotational wear with a wear wheel CS # 10 and a load of 500 g. Then, the surface abrasion state of this test piece was observed, and the wear resistance was evaluated by the following index.

A: Almost not worn ○: A little worn Δ: Worn considerably, but not torn ×: Worn significantly and torn is conspicuous Net durability (strong retention)
The durability model test was conducted by the following method and evaluated by the strength retention rate of the net.

First, after laying a 2m square net on the concrete alley, 200 kg of cobblestone with a diameter of 5-10cm falls from the 2m height to the center of the net (50cm square) over 1 minute. I let you. After repeating this operation 20 times, the cobblestone was removed, and a strip-shaped test piece measuring 25 cm in length and 7.5 cm in width was cut out from the center of the net. Next, the strength S ₁ of this test piece was measured, and the strength retention rate was determined by the following formula using this S 1 and the strength S ₀ before the test. The strength was determined by the same method as in C above, and the average value of n number 20 was obtained.

Strength retention (%) = (S ₁ / S ₀ ) × 100
H. Biodegradability of the net The net was buried in the ground (depth 50 cm from the ground surface) and dug up two years later to observe the state of the net.

◎: Decomposition has progressed considerably, and there are many locations with large holes ○: Decomposition has progressed, and there are some locations with holes △: There are no locations with holes, but partial The knitted fabric is starting to become thin ×: Almost unchanged from landfill. Net flame retardancy Measured according to JIS L1091 (Method D).

[Production Example 1] (Production of polylactic acid)
A lactide produced from L-lactic acid having an optical purity of 99.5% is present in the presence of a bis (2-ethylhexanoate) tin catalyst (lactide to catalyst molar ratio = 10,000: 1) at 180 ° C. for 200 minutes in a nitrogen atmosphere. Polymerization was performed to obtain polylactic acid P1. The relative viscosity of the obtained polylactic acid was 4.0.

[Production Example 2] (Production of polylactic acid containing 4% by weight of EBA)
After drying polylactic acid P1 and ethylenebisstearic acid amide (EBA) [“Alfro H-50S” manufactured by NOF Corporation], weigh EBA so that polylactic acid P1: EBA = 96: 4 (weight ratio). The polylactic acid P2 containing 4% by weight of EBA was obtained by using a biaxial kneading extruder with a cylinder temperature of 220 ° C. while continuously adding to P1.

[Production Example 3] (Production of polylactic acid containing 4% by weight of SS)
Polylactic acid P3 containing 4% by weight of SS was prepared in the same manner as in Production Example 2 except that EBA was changed to N-stearyl stearamide (SS) [Nika Amide S] manufactured by Nippon Kasei Co., Ltd., an alkyl-substituted monoamide. Obtained.

[Production Example 4] (Production of polylactic acid containing 4% by weight of SA)
Polylactic acid P4 containing 4% by weight of SA was obtained in the same manner as in Production Example 2, except that EBA was changed to monoamide stearamide (SA) [“Alfro S-10” manufactured by NOF Corporation].

[Production Example 5] (Production of polylactic acid containing 15% by weight of colorant)
Polylactic acid P1: Colorant (carbon black) = 85: 15 (weight ratio) was used in the same manner as in Production Example 2 to obtain polylactic acid P5 containing 15% by weight of the colorant.

[Production Example 6] (Production of polylactic acid containing 15% by weight of a flame retardant)
Polylactic acid P1: a flame retardant ((2- (β-hydroxyethoxycarbonyl) ethyl) methylphosphinic acid) = 85: 15 (weight ratio), in the same manner as in Production Example 2, containing 15% by weight of a flame retardant Lactic acid P6 was obtained.

Example 1
Chip blend (EBA 1% by weight) so that the weight ratio of polylactic acid P1: polylactic acid P2 = 3: 1 was charged into a hopper, the chip was melted at 220 ° C. with an extruder, and then heated to 220 ° C. The molten polymer was introduced into a spin pack installed in the block, and spun from a 192-hole die having a hole diameter of 0.6 mm.

  A heating cylinder of 30 cm was attached just below the base and heated so that the temperature in the cylinder 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 immediately below the heating cylinder, and cold oil at 30 ° C. was blown onto the yarn at a rate of 30 m / min to cool and solidify, and then an oil was applied. Oils include iso-C24 alcohol / thiodipropionic acid ester (40% by weight), C11-15 alcohol AOA / thiodipropionic acid ester (30% by weight), trimethylolpropane AOA distearate (10% by weight), C8 alcohol AOA ( 10% by weight), hydrogenated castor oil (7% by weight), and stearylamine EO15 (3% by weight) diluted with mineral oil to 20% by weight were used as a non-aqueous oil agent.

  The unstretched yarn provided with the oil was wound around a take-up roll (1FR) rotating at a speed of 500 m / min. Next, the take-up yarn is continuously wound without being wound once, and stretched 1.5% between the take-up roll and the yarn supply roll (2FR), and then the three-stage heat is applied. After stretching, the film was wound after giving 1.5% relaxation (FIG. 1). 1FR is 60 ° C, 2FR is 100 ° C, the first stretching roll (1DR) is 115 ° C, the second stretching roll (2DR) is 140 ° C, and the third stretching roll (3DR) is 140 ° C. Lu (RR) was not heated.

  In addition, the entanglement nozzle was attached between the relaxation roll and the winder, and the entanglement was imparted to the fiber by injecting 0.2 MPa of compressed air. The first stage draw ratio was set to 34% of the total draw ratio, and the second stage and third stage draw ratios were both set to 33%. Thus, 1,100 dtex-192 fil of polylactic acid fiber was obtained. The obtained fiber exhibited good yarn properties such as a strength of 5.6 cN / dtex, an elongation of 31.1%, and a dry heat shrinkage of 6.8%.

This fiber was knitted with a front of 7,000 dtex and a back of 4,700 dtex using a Russell knitting machine, and a safety net having a basis weight of 300 g / m ² and a mesh of 15 mm was produced. The obtained safety net was excellent in wear resistance and durability, and had moderate biodegradability in soil.

Example 2
A polylactic acid fiber and a safety net made thereof were obtained in the same manner as in Example 1 except that only polylactic acid P2 (EBA was 4% by weight) was used. The obtained safety net was extremely excellent in wear resistance and durability, and had moderate biodegradability in soil.

Example 3
A polylactic acid fiber and a safety net comprising the same were prepared in the same manner as in Example 1 except that the charging ratio of polylactic acid P1 and polylactic acid P2 was 12.3: 1 by weight (EBA was 0.3% by weight). Obtained. The obtained safety net was excellent in wear resistance and durability, and had moderate biodegradability in soil.

Example 4
A polylactic acid fiber and a safety net made thereof were obtained in the same manner as in Example 1 except that polylactic acid P3 was used instead of polylactic acid P2. The obtained safety net was excellent in wear resistance and durability, and had moderate biodegradability in soil.

Example 5
The safety net obtained in Example 1 was dyed under the following conditions. When the fiber was unwound from a part of the net after dyeing and the strength was measured, 4.2 cN / dtex was found to be lower in strength than before dyeing (5.6 cN / dtex). The obtained safety net was somewhat inferior in wear resistance and durability compared to the safety net before dyeing (Example 1), but showed moderate net characteristics and moderate biodegradability in soil. It was what had.

<Dyeing conditions>
-Dye: Dianix Navy Blue ERFS 200 (2% owf)
-Auxiliary agent: pH adjuster (0.2 g / l)
-Temperature x time: 110 ° C x 40 minutes Example 6
Same as Example 1 except that chip blend (EBA 1 wt%, colorant 0.3 wt%) was made so that polylactic acid P1: polylactic acid P2: polylactic acid P5 = 3: 1: 0.08 by weight ratio. Thus, a polylactic acid fiber and a safety net comprising the same were obtained. The obtained safety net was excellent in wear resistance and durability, and had moderate biodegradability in soil.

Example 7
Example 1 except that the chip blend (EBA 1% by weight, flame retardant 0.9% by weight) was made so that polylactic acid P1: polylactic acid P2: polylactic acid P6 = 3: 1: 0.25 by weight ratio. Thus, a polylactic acid fiber and a safety net comprising the same were obtained. The obtained safety net was excellent in wear resistance and durability, and had moderate biodegradability in soil. Further, as a result of the flame retardancy test, it was found that the flame retardancy was improved as compared with the safety net of Example 1.

Comparative Example 1
A polylactic acid fiber and a safety net made thereof were obtained in the same manner as in Example 1 except that only polylactic acid P1 was used. The obtained safety net had good biodegradability but was inferior in wear resistance and durability and did not sufficiently satisfy the characteristics of the safety net.

Comparative Example 2
A polylactic acid fiber and a safety net made thereof were obtained in the same manner as in Example 1 except that polylactic acid P4 was used instead of polylactic acid P2. The obtained fiber has low strength, and the obtained safety net has good biodegradability, but is inferior in wear resistance and durability, and sufficiently satisfies the characteristics of the safety net. It wasn't. It is suggested that these poor characteristics are caused by a decrease in the molecular weight of polylactic acid caused by stearamide, which is a fatty acid monoamide.

It is a figure which shows a direct spinning drawing apparatus.

Explanation of symbols

1: Hopper 2: Extrusion kneader (Extruder)
3: Spin block 4: Spin pack 5: Base 6: Heating cylinder 7: Chimney 8: Oiling device (oiling roller)
9: Take-up roll (1FR)
10: Yarn supply roll (2FR)
11: First stretching roll (1DR)
12: Second stretching roll (2DR)
13: Third stretching roll (3DR)
14: Relaxation roll (RR)
15: Entangling nozzle 16: Winder

Claims (5)

A net comprising polylactic acid fiber containing 0.1 to 5% by weight of fatty acid bisamide and / or alkyl-substituted fatty acid monoamide with respect to the whole fiber. The net according to claim 1, wherein the polylactic acid fiber has a fineness of 250 to 5,000 dtex, a strength of 4.5 to 7.0 cN / dtex, and an elongation of 15 to 40%. The net according to claim 1 or 2, wherein the polylactic acid fiber is an original yarn. The net according to any one of claims 1 to 3, wherein the mesh is 5 to 200 mm. The net according to any one of claims 1 to 4, wherein one of a safety net, a curing net, a rockfall prevention net, a snow net, a slope protection net, a revetment suction prevention net, a sports net, and a fishing net A net characterized by being one type.

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