Highly functional polyethylene fiber and method for producing same

Abstract

The purpose of the present invention is to provide a high-performance polyethylene fiber that uses a biomass-derived raw material and has satisfactory mechanical characteristics. A highly functional polyethylene fiber according to the present invention contains: a polyethylene resin A having an Mw / Mn of at least 3 and a biomass degree, as calculated by measurement of the radioactive carbon (14C) by using an accelerator mass spectrometer (AMS), of at least 1%; and a polyethylene resin B having an Mw / Mn of not more than 6. The proportion of the polyethylene resin A in 100 mass% for the total of the polyethylene resin A and the polyethylene resin B is 20-90 mass%.

Description

High-performance polyethylene fiber and its manufacturing method

[0001] The present invention relates to a high-performance polyethylene fiber containing a biomass-derived polyethylene resin and another polyethylene resin different from the biomass-derived polyethylene resin, and a method for producing the same.

[0002] Polyethylene fibers are used in a variety of products, including braids, woven fabrics, knitted fabrics, nonwoven fabrics, bags, and vests, as well as in medical applications such as medical sutures and artificial ligaments. As the uses of polyethylene fibers become more diverse, polyethylene fibers with functionality suited to the required characteristics of these products are in demand. For example, ultra-high molecular weight polyethylene fibers with high strength and high elastic modulus are used in braids made of multifilaments or monofilaments, which are used in many applications such as fishing lines, nets, and ropes. Furthermore, high-strength polyethylene fibers with excellent cut resistance are used in fields requiring cut resistance, such as gloves and vests (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2004-019050

[0004] High-performance polyethylene fibers made from biomass-derived materials have lower mechanical properties, such as tensile strength and initial modulus, compared to high-performance polyethylene fibers made from fossil fuel-derived materials. Furthermore, when biomass-derived materials are used, defects such as thread breakage frequently occur during the fiber manufacturing process, resulting in low productivity.

[0005] An object of the present invention is to provide a high-performance polyethylene fiber using a biomass-derived raw material and having sufficient mechanical properties. Another object of the present invention is to provide a method for producing the high-performance polyethylene fiber while suppressing yarn breakage and ensuring high productivity.

[0006] [1] The high-performance polyethylene fiber of the present invention is characterized by radiocarbon ( １４C) The polyethylene resin A has a biomass degree of 1% or more as calculated by measurement and an Mw / Mn of 3 or more, and a polyethylene resin B has an Mw / Mn of 6 or less, and the proportion of the polyethylene resin A is 20 to 90% by mass based on a total of 100% by mass of the polyethylene resin A and the polyethylene resin B.

[0007] [2] The high-performance polyethylene fiber according to [1], having a tensile strength of 8 cN / dtex or more and an initial modulus of elasticity of 200 cN / dtex or more.

[0008] [3] The high-performance polyethylene fiber according to [1] or [2], wherein the degree of elongation of the polyethylene fiber calculated by the following formula is 25% or less: Elongation = [(L(t) - L0) / L0] x (100), where L0 is the length of the polyethylene fiber before the start of measurement, and L(t) is the length of the polyethylene fiber 100 minutes after the start of elongation measurement under the load at which the tensile strength (cN / dtex) of the polyethylene fiber becomes 30%, which is set as the set load.

[0009] [4] High-performance polyethylene fibers according to [1] to [3], wherein the shrinkage percentage of the polyethylene fiber according to JIS L1013 satisfies the following (1) and (2): (1) the shrinkage percentage measured when the polyethylene fiber is heated at 40°C for 30 minutes and then allowed to cool is 0.8% or less, and (2) the shrinkage percentage measured when the polyethylene fiber is heated at 120°C for 30 minutes and then allowed to cool is 6% or more.

[0010] [5] The high-performance polyethylene fiber according to any one of [1] to [4], wherein the single fiber fineness is 0.5 to 10 dtex.

[0011] [6] The high-performance polyethylene fiber according to any one of [1] to [5], wherein the polyethylene fiber has a weight-average molecular weight of 70,000 to 1,000,000 and an Mw / Mn ratio of 10 or less.

[0012] [7] The high-performance polyethylene fiber according to any one of [1] to [6], which contains at least one alkyl side chain selected from the group consisting of a methyl group, an ethyl group, and a butyl group, and has 0.3 or more alkyl side chains per 1,000 carbon atoms.

[0013] [8] The high-performance polyethylene fiber according to any one of [1] to [7], which has a coupe tester index value of 4.0 or more as measured based on the European Standard EN388 method.

[0014] [9] The cool-to-the-touch value measured according to JIS L1927 is 0.1 W / cm ２ The high-performance polyethylene fiber according to any one of [1] to [8] above.

[0015]

[10] The high-performance polyethylene fiber according to any one of [1] to [9], wherein the thermal conductivity measured by contacting the polyethylene fiber at 20°C with a heat source plate at 30.0°C is 0.05 to 0.40 W / (m K).

[0016]

[11] The high-performance polyethylene fiber according to any one of [1] to

[10] , wherein the value obtained by dividing the molecular weight distribution (Mw / Mn) of the polyethylene resin A by the molecular weight distribution of the polyethylene resin B ([Mw / Mn of polyethylene resin A] / [Mw / Mn of polyethylene resin B]) is 1.3 to 4.0.

[0017]

[12] The high-performance polyethylene fiber according to any one of [1] to

[11] , further comprising another resin other than the polyethylene resin A and the polyethylene resin B.

[0018]

[13] The high-performance polyethylene fiber according to

[12] , wherein the other resin is a polyethylene resin other than the polyethylene resin A and the polyethylene resin B.

[0019]

[14] The high-performance polyethylene fiber according to any one of [1] to

[13] , wherein the high-performance polyethylene fiber essentially consists of the polyethylene fiber A and the polyethylene fiber B.

[0020]

[15] A product comprising the high-performance polyethylene fiber according to any one of [1] to

[14] .

[0021]

[16] Radiocarbon ( １４C) A method for producing a high-performance polyethylene fiber, comprising: a step of melt-extruding a resin mixture of polyethylene resin A, which has a biomass degree of 1% or more as calculated by measurement and an Mw / Mn of 3 or more, and polyethylene resin B, which has an Mw / Mn of 6 or less, at a temperature 10°C or more higher than the melting point of the resin mixture; a spinning step of supplying the melt-extruded resin mixture to a spinning nozzle at a temperature 80°C or more higher than the melting point of the resin mixture; a step of cooling the fibrous material obtained by discharging from the spinning nozzle and then winding it up at 25 m / min or more; and a drawing step of drawing the fibrous material at a temperature not higher than the melting point of the obtained fibrous material at least once or more times to a draw ratio of 5 times or more, wherein the ratio of the deformation in the spinning step to the deformation in the drawing step (deformation in the spinning step / deformation in the drawing step) is 100 or less.

[0022] According to the present invention, a high-performance polyethylene fiber having sufficient mechanical properties can be provided. Furthermore, according to the production method of the present invention, the high-performance polyethylene fiber can be produced while suppressing yarn breakage and ensuring high productivity.

[0023] The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result have found that a polyethylene fiber containing polyethylene resin A having a biomass degree of at least 1% as calculated by radiocarbon measurement using an accelerator mass spectrometer (AMS) and a molecular weight distribution (Mw / Mn) of 3 or more, and polyethylene resin B different from polyethylene resin A and having a molecular weight distribution (Mw / Mn) of 6 or less, in a predetermined ratio (polyethylene resin A: 20 to 90% by mass), has excellent mechanical properties, which led to the present invention.

[0024] The polyethylene resin A and polyethylene resin B that constitute the high-performance polyethylene fiber of the present invention will now be described.

[0025] Polyethylene Resin A The polyethylene resin A constituting the high-performance polyethylene fiber of the present invention was analyzed by radiocarbon ( １４ C) The biomass ratio calculated by measurement is 1% or more, and Mw / Mn is 3 or more.

[0026] In the present invention, "biomass" refers to renewable organic resources derived from living organisms, excluding fossil resources. Specific examples of biomass include livestock resources such as livestock excrement, food resources such as processing residues, food waste, and animal and plant residues, industrial resources such as pulp waste liquid, sawmill residues, and construction wood, waste biomass such as sewage sludge, forestry resources such as forest residues, agricultural resources such as rice straw, rice husks, and wheat straw, unused biomass such as marine resources such as shells and seaweed, carbohydrate resources such as sugarcane and sugar beet, starch resources such as rice, potatoes, and corn, oil resources such as rapeseed, soybeans, peanuts, oil palm, and castor beans, and herbaceous resources such as Erianthus.

[0027] Biomass Degree In the present invention, a polyethylene resin having a biomass degree of 1% or more is used as polyethylene resin A. A polyethylene resin having a biomass degree of 1% or more means that 1% or more of the raw material of the polyethylene resin is derived from biomass. The biomass degree of polyethylene resin A is preferably 1% or more, more preferably 40% or more, even more preferably 60% or more, and most preferably 80% or more. A higher biomass degree is desirable because it reduces the environmental load. The biomass degree is the content of biomass-derived carbon relative to the total carbon in the polyethylene raw material, and is determined by radiocarbon ( １４ C). In the present invention, the biomass degree of the polyethylene raw material is measured, and this is taken as the biomass degree of the polyethylene resin. Polyethylene resin A may be composed of a non-biomass component, for example, a polyethylene resin derived from a fossil fuel, with the remainder being composed of a non-biomass component, depending on the biomass degree. Furthermore, polyethylene resin A may contain preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 0% by mass of a fossil fuel-derived polyolefin resin (other resin), or inorganic metals such as lithium, calcium, magnesium, aluminum, barium, silicon, cobalt, chromium, zinc, iron, copper, zirconium, antimony, hafnium, manganese, sodium, nickel, phosphorus, and titanium as catalyst residues or the like.

[0028] The molecular weight distribution (Mw / Mn) of the polyethylene resin A of the present invention is 3 or more, preferably 3 to 10, more preferably 4.5 to 9, and even more preferably 6.0 to 8. When mixed with the polyethylene resin B described below in a predetermined ratio, the polyethylene resin A having a molecular weight distribution in the above range exhibits excellent mechanical properties. In addition, it exhibits excellent productivity in the production of polyethylene fibers.

[0029] Polyethylene Resin B The polyethylene resin B constituting the high-performance polyethylene fiber of the present invention has a molecular weight distribution (Mw / Mn) of 6 or less. Molecular Weight Distribution The molecular weight distribution of polyethylene resin B is 6 or less, preferably 2 to 6, more preferably 2 to 5.5, and even more preferably 2.5 to 5.0. A lower molecular weight distribution of polyethylene resin B contributes to improved mechanical properties and improved productivity of the high-performance polyethylene fiber. In particular, adjusting the molecular weight distribution of polyethylene resin B so that it does not overlap with the molecular weight distribution of polyethylene resin A provides a more excellent effect in improving mechanical properties.

[0030] Biomass Degree Polyethylene resin B is a polyethylene resin different from polyethylene resin A, as long as it satisfies the above molecular weight distribution. Polyethylene resin B may be a single polyethylene resin or a mixture of multiple polyethylene resins. Furthermore, polyethylene resin B is preferably made from a fossil fuel-derived raw material from the viewpoint of improving mechanical properties, but it may also be made from a biomass-derived raw material or a mixed raw material of a biomass-derived raw material and a fossil fuel-derived raw material. The biomass degree is not particularly limited, but the higher the biomass degree of polyethylene resin B, the greater the effect of reducing the environmental load. The biomass degree of polyethylene resin B is preferably 1% or more, more preferably 10% or more, and even more preferably 20% or more. Polyethylene resin B may contain catalyst residues, other resins, etc. in the same range as polyethylene resin A.

[0031] Of the total (100% by mass) of polyethylene resin A and polyethylene resin B, the amount of polyethylene resin A is 20 to 90% by mass, preferably 25 to 85% by mass, and more preferably 30 to 80% by mass. By setting the proportion of polyethylene resin A within this range, it is possible to ensure mechanical properties while reducing the environmental load.

[0032] In a preferred embodiment of the present invention, the value obtained by dividing the molecular weight distribution (Mw / Mn) of polyethylene resin A by the molecular weight distribution of polyethylene resin B ([Mw / Mn of polyethylene resin A] / [Mw / Mn of polyethylene resin B]) is preferably 1.3 to 4.0, more preferably 1.4 to 3.0, and even more preferably 1.5 to 2.5. When the relationship between the molecular weight distribution of polyethylene resin A and the molecular weight distribution of polyethylene resin B satisfies the above range, it contributes to improving mechanical properties. Furthermore, in a preferred production method of the present invention, productivity can be improved by using raw materials mixed in this range.

[0033] The high-performance polyethylene fiber of the present invention may be substantially composed of polyethylene resin A and polyethylene resin B. "Substantially" means that small amounts of other components may be contained as long as the effects of the invention are not impaired. In one embodiment, the high-performance polyethylene fiber of the present invention may contain or substantially consist of other resins other than polyethylene resin A and polyethylene resin B. Examples of other resins include low-density polyethylene resins and polypropylene resins, and one or more of these other resins may be contained. The other resin may also be a polyethylene resin other than polyethylene resins A and B. When the high-performance polyethylene fiber of the present invention contains other resins, the total amount of polyethylene resin A and polyethylene resin B is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 95 parts by mass or more, per 100 parts by mass of the resins constituting the high-performance polyethylene fiber, with the remainder being the other resin. Furthermore, it is a preferred embodiment that various known additives may be contained as necessary. The high-performance polyethylene fiber of the present invention may contain one or more additives. Examples of additives include oils, crosslinking agents, plasticizers, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, reinforcing agents, hard particles, antistatic agents, pigments, dyes, and modifying resins.

[0034] In the present invention, the high-performance polyethylene fiber preferably satisfies the following (1) mechanical properties: tensile strength and initial modulus. More preferably, in addition to the (1) mechanical properties, the fiber satisfies at least one of (2) elongation, (3) shrinkage, (4) single fiber fineness, (5) weight-average molecular weight and molecular weight distribution (Mw / Mn), and (6) number of alkyl side chains. More preferably, the fiber satisfies at least two, three, or more, and even more preferably four or more, or all, of these properties. In another preferred embodiment, the high-performance polyethylene fiber of the present invention also satisfies at least one, two, or more, or all, of (7) index value, (8) coolness to the touch (Q-max), and (9) thermal conductivity. While the fiber may satisfy either one of the properties (2) to (6) and the properties (7) to (9), it is preferable to satisfy both.

[0035] (1) Mechanical Properties The mechanical properties of the high-performance polyethylene fiber of the present invention preferably satisfy both tensile strength and initial modulus. Tensile strength: The tensile strength is preferably 8 cN / dtex or more, more preferably 8 to 30 cN / dtex, even more preferably 10 to 25 cN / dtex, and most preferably 12 to 25 cN / dtex. The higher the tensile strength, the more sufficient strength can be imparted. Initial modulus: The initial modulus is 200 cN / dtex or more, preferably 200 to 700 cN / dtex, and more preferably 250 to 600 cN / dtex. The higher the initial modulus, the more effectively the fiber can suppress changes in physical properties and shape due to external forces.

[0036] (2) Elongation (Creep Resistance) The high-performance polyethylene fiber of the present invention preferably has an elongation calculated from the following formula of 25% or less, more preferably 0.5 to 15%, and even more preferably 1.0 to 10%. The lower the elongation, the more dimensional stability at room temperature can be ensured, and the more excellent creep resistance is exhibited. Furthermore, in consideration of the productivity of the product in post-processing, it is desirable that the elongation be within the above range. Elongation = [(L(t) - L ０ ) / L ０ ]×(100) where L ０L(t): Length of polyethylene fiber before measurement begins L(t): Length of polyethylene fiber 100 minutes after starting elongation measurement under a load that is set as a load at which the tensile strength (cN / dtex) of the polyethylene fiber becomes 30%. The method for measuring tensile strength is the same as in (1) above.

[0037] (3) Shrinkage The high-performance polyethylene fiber of the present invention has a 40°C shrinkage measured under the conditions described in the Examples based on JIS L1013 of preferably 0.8% or less, more preferably 0.7% or less, and even more preferably 0.5% or less, and a 120°C shrinkage of preferably 6% or more, more preferably 6.5% or more, and even more preferably 7.0% or more. A low 40°C shrinkage can ensure dimensional stability at room temperature. A high 120°C shrinkage is also preferred because it allows for high-temperature molding in a subsequent process.

[0038] (4) Single Yarn Fineness The average single yarn fineness of the high-performance polyethylene fiber of the present invention is preferably 0.5 to 10 dtex, more preferably 0.6 to 10 dtex, and even more preferably 0.6 to 5.0 dtex. The higher the average single yarn fineness, the more sufficient strength can be imparted to the high-performance polyethylene fiber of the present invention. Furthermore, woven or knitted fabrics (woven or knitted fabrics) using the high-performance polyethylene fiber within the above range are preferred because they do not have a stiff feel and do not lose their flexibility.

[0039] (5) Weight-Average Molecular Weight The weight-average molecular weight of the high-performance polyethylene fiber of the present invention is preferably 70,000 to 1,000,000, more preferably 100,000 to 500,000, and even more preferably 200,000 to 350,000. By adjusting the weight-average molecular weight within the above range, the strength of the high-performance polyethylene fiber of the present invention can be increased. Furthermore, in the production method described below, if the weight-average molecular weight is too low, defects due to molecular chain ends increase, which may result in reduced stretchability and reduced productivity. On the other hand, if the weight-average molecular weight is too high, for example, the melt viscosity during spinning may become very high, making it difficult to extrude the fiber from a spinning nozzle.

[0040] Molecular Weight Distribution of High-Performance Polyethylene Fibers The high-performance polyethylene fibers of the present invention preferably satisfy the above weight-average molecular weight and also satisfy the molecular weight distribution (Mw / Mn), and the molecular weight distribution (Mw / Mn) is preferably 10 or less, more preferably 3.0 to 8.0, and even more preferably 4.0 to 7.0. The above range is desirable in consideration of the balance between polyethylene resin A and polyethylene resin B and the mechanical properties. Furthermore, in the preferred production method described below, if the molecular weight distribution is too small, the melt viscosity during spinning will become very high, which may make it difficult to discharge the fiber from the spinning nozzle. On the other hand, if the molecular weight distribution is too large, productivity may decrease due to the influence of short and long molecular chains.

[0041] (6) Number of Alkyl Side Chains (per 1,000 carbon atoms) The high-performance polyethylene fiber of the present invention preferably has 0.3 to 10.0 alkyl side chains per 1,000 carbon atoms, more preferably 0.5 to 0.8, and even more preferably 1.0 to 5.0. The more alkyl side chains there are, the better the creep properties and dimensional stability. On the other hand, if there are too many alkyl side chains, stretchability may be impaired. The alkyl side chain is at least one selected from the group consisting of a methyl group, an ethyl group, and a butyl group.

[0042] (7) Index Value (Coop Index) The index value is an index value measured using a coupe tester based on European Standard (EN388 method). The index value of the high-performance polyethylene fiber of the present invention is preferably 4.0 or more, more preferably 4.5 or more, and even more preferably 5.0 or more. A higher index value can improve cut resistance, making it suitable for protective woven and knitted fabrics, etc.

[0043] (8) Coolness to the Touch (Q-max) Coolness to the touch is a characteristic that indicates the coolness to the touch of a fabric, and is the maximum value of the initial heat flux (Q-max: W / cm) measured based on JIS L1927 when the skin comes into contact with the fabric. ２ The high-performance polyethylene fiber of the present invention has a cool feeling to the touch of 0.1 W / cm ２ It is desirable that the value is equal to or greater than 0.1 W / cm or more, and preferably 0.1 to 1.0 W / cm ２, more preferably 0.15 to 0.8 W / cm ２ , and more preferably 0.2 to 0.6 W / cm ２ , most preferably 0.25 to 0.6 W / cm ２ The higher the coolness to the touch, the more the coolness of the skin in contact with the polyethylene fiber can be improved.

[0044] (9) Thermal Conductivity The thermal conductivity is a value measured by bringing a heat source plate at 30.0°C (ΔT = 10°C) into contact with a test piece at 20°C. The thermal conductivity of the high-performance polyethylene fiber of the present invention is preferably 0.05 to 0.40 W / (m K), more preferably 0.10 to 0.35 W / (m K), even more preferably 0.15 to 0.30 W / (m K), and most preferably 0.20 to 0.30 W / (m K). The higher the thermal conductivity, the more easily a cool feeling can be obtained, which is preferable.

[0045] Fiber Structure: The structure of the high-performance polyethylene fiber of the present invention is not limited, and may be, for example, a composite fiber such as a core-sheath structure in which the high-performance polyethylene fiber of the present invention is combined with other fibers. When the high-performance polyethylene fiber of the present invention has a core-sheath structure, the high-performance polyethylene fiber of the present invention may be either the core or the sheath. The other fiber is not particularly limited, but is preferably a fiber with a biomass degree of 95% or more, more preferably a polyethylene fiber containing a polyethylene resin with a biomass degree of 95% or more that contains different amounts of additives or other resins. The cross section of the high-performance polyethylene fiber is not limited, and may have any shape, such as a circle, star, triangle, or hollow cross section.

[0046] Products The high-performance polyethylene fiber of the present invention can be used in various products. In such cases, it is desirable to appropriately adjust the above-mentioned physical properties depending on the required characteristics of the product. Examples of products using the high-performance polyethylene fiber of the present invention include, but are not limited to, woven fabrics, knitted fabrics, nonwoven fabrics, bags, braided cords, nets, gloves, fishing lines, ropes, medical sutures, artificial ligaments, and vests. Furthermore, it is sufficient that at least a part of the product contains the high-performance polyethylene fiber of the present invention, and the proportion of the high-performance polyethylene fiber in the product is not limited.

[0047] The high-performance polyethylene fiber of the present invention is suitable for, for example, woven and knitted fabrics, and is particularly suitable for products requiring cut resistance, such as cut-resistant woven and knitted fabrics, gloves, and vests. Gloves can be produced, for example, by using the polyethylene fiber of the present invention on a knitting machine, or by weaving the polyethylene fiber of the present invention into fabric, which can then be cut and sewn into gloves. The gloves can be used as is, or, if necessary, can be coated with an anti-slip material such as a urethane resin or an ethylene resin to provide anti-slip properties.

[0048] In particular, since the polyethylene fiber of the present invention has excellent cut resistance, it is suitably used, for example, in fiber-reinforced resin reinforcing materials, cement reinforcing materials, fiber-reinforced rubber reinforcing materials, or protective materials that are expected to be subject to environmental changes, bulletproof materials, medical sutures, artificial tendons, artificial muscles, machine tool parts, battery separators, chemical filters, etc. Of course, products using the polyethylene fiber of the present invention are not limited to these.

[0049] The high-performance polyethylene fiber of the present invention has high strength and excellent moldability. Therefore, it can be processed into woven fabrics, knitted fabrics, nonwoven fabrics, braided cords, nets, etc. Specific applications include fishing lines and ropes in addition to the gloves and vests mentioned above. Furthermore, it is suitable for, for example, tapes, material protective covers, sheets, kite lines, bags, interior materials, backpacks, footwear, sportswear, outdoor wear, tactical wear, workwear, performance apparel, bowstrings, sailcloth, tents, and tent materials.

[0050]

[0033] The following describes the melt spinning method, which is a suitable method for producing the high-performance polyethylene fiber of the present invention. In consideration of productivity, the high-performance polyethylene fiber of the present invention is preferably produced by the melt spinning method. If the fiber is produced by the gel spinning method, frequent fiber breakage and other problems occur, reducing productivity, and the solvent may remain in the polyethylene fiber.

[0051] In the present invention, polyethylene resin A and polyethylene resin B that satisfy the above requirements and other suitable requirements as needed are used. Polyethylene resin A and polyethylene resin B may be obtained from various known raw materials and various known production methods. Furthermore, the type of biomass raw material and the production method are not limited. For example, polyethylene resins produced from biomass-derived raw materials can be used, such as polyethylene resins obtained by dehydrating ethanol (biomass ethanol) obtained by fermenting biomass raw materials and polymerizing the resulting ethylene, or polyethylene resins obtained by chemically treating biomass raw materials. Furthermore, polyethylene resins produced by mixing biomass-derived raw materials and fossil fuel-derived raw materials, or mixed resins of polyethylene resins produced from biomass-derived raw materials and polyethylene resins produced from fossil fuel-derived raw materials, may be used as polyethylene resin A or polyethylene resin B.

[0052] Melt Extrusion Process In the present invention, radiocarbon ( １４ C) A polyethylene resin A having a biomass content of 1% or more as calculated by measurement and an Mw / Mn ratio of 3 or more is mixed with a polyethylene resin B having an Mw / Mn ratio of 6 or less (hereinafter sometimes referred to as the "resin mixture") and extruded in a molten state using a melt extruder or the like. Polyethylene resin A and polyethylene resin B are mixed within the above-mentioned range of polyethylene resin A ratio. In this case, it is preferable that one or more of the above-mentioned molecular weight distribution, weight average molecular weight, and other properties are satisfied as needed. The polyethylene resin A and polyethylene resin B may be mixed by either dry blending or melt blending. The temperature of the resin mixture to be melt-extruded is preferably 10°C or higher, more preferably 50°C or higher, and even more preferably 80°C or higher, higher than the melting point of the resin mixture. Melt extrusion is desirably carried out in an inert atmosphere, and it is preferable to supply an inert gas such as nitrogen to the extruder. The pressure of the inert gas to be supplied is not limited, but is preferably 0.001 to 0.8 MPa, more preferably 0.05 to 0.7 MPa, and even more preferably 0.1 to 0.5 MPa.

[0053] The melt-extruded molten resin composition is supplied to a spinning nozzle at a melt temperature that is 80°C or higher, preferably 100°C or higher, than the melting point of the resin composition using a constant-rate supply device, etc. The hole diameter of the spinning nozzle is not limited, but is preferably 0.3 to 2.5 mm, more preferably 0.5 to 1.5 mm.

[0054] The single-hole discharge rate of the molten resin composition discharged from the spinning nozzle is not limited, but is preferably 0.05 to 1.0 g / min, more preferably 0.1 to 0.5 g / min. If the single-hole discharge rate is high, spinning may become unstable due to the occurrence of melt fracture, etc. Furthermore, taking into account the amount of deformation in the spinning process described below, the discharge linear speed is preferably 0.01 to 19 m / min, more preferably 0.1 to 10 m / min, and even more preferably 0.1 to 3 m / min.

[0055] Winding Process The fibrous material discharged from the spinning nozzle is preferably passed through a heat-retaining section and then cooled using an appropriate cooling means. Various known cooling means can be used, such as air cooling, refrigerant cooling using water, methanol, ethanol, or a mixed solvent of these, or a combination of air cooling and a refrigerant. Air cooling is preferred in consideration of cooling costs. The cooling air velocity during air cooling is not limited, but is preferably 0.1 to 5.0 m / s, more preferably 0.5 to 3.0 m / s, and even more preferably 0.5 to 1.0 m / s. The temperature of the fibrous material after cooling is preferably 5 to 40°C, more preferably 10 to 35°C, and even more preferably 15 to 30°C.

[0056] After cooling, the fibrous material is wound up at a constant speed. The winding speed is not limited, but is desirably 25 m / min or more, preferably 25 to 500 m / min, more preferably 50 to 400 m / min, and even more preferably 100 to 300 m / min.

[0057] Stretching Step Next, the wound fibrous material is stretched using a temperature-controllable roller or the like. The number of stretching times is preferably one or more, more preferably two or more. The total stretching ratio (total when stretching multiple times) is desirably 5 times or more, preferably 5 to 30 times, more preferably 6 to 25 times, and even more preferably 7 to 20 times. Furthermore, when stretching multiple times (for example, stretching twice), the stretching ratio in the first stage is preferably 1.05 to 4.0 times, more preferably 2.0 to 3.0 times. The stretching ratio in the second stage is preferably 2.5 to 15 times, more preferably 5.0 to 10 times.

[0058] The stretching temperature is preferably equal to or lower than the melting point of the resin composition constituting the fibrous material. When stretching is performed multiple times, the roller temperature in the first stage (initial stretching temperature) is preferably lower than the crystal dispersion temperature of the fiber, and the stretching temperature is preferably set to 80°C or lower, more preferably 70°C or lower. The stretching temperature in the second stage is preferably equal to or higher than the crystal dispersion temperature of the fiber, and the stretching temperature is preferably 90°C or higher. The stretching temperature is preferably equal to or lower than the melting point of the fiber, and more preferably lower than the melting point of the fiber.

[0059] In the present invention, it is desirable to adjust the deformation amounts in the spinning process and the drawing process so that the following relationship is satisfied. Deformation amount in the spinning process The deformation amount in the spinning process is a value calculated by [spinning speed (g / min) / discharge linear speed (g / min)]. Discharge linear speed is the discharge amount per hole of the spinning nozzle, and is a value calculated by [(discharge amount / number of nozzle holes) / area per nozzle hole]. Deformation amount in the drawing process The deformation amount in the drawing process is the total draw ratio in the drawing process. Deformation ratio The ratio of the deformation amount in the spinning process to the deformation amount in the drawing process (deformation amount in the spinning process / deformation amount in the drawing process) is preferably 100 or less, more preferably 90 or less. If the deformation ratio exceeds 100, the high-performance polyethylene fiber of the present invention may not have sufficient strength.

[0060] This application claims the benefit of priority based on Japanese Patent Application No. 2024-053331, filed on March 28, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-053331, filed on March 28, 2024, are incorporated herein by reference.

[0061] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples and can be practiced with appropriate modifications within the scope of the above-mentioned and below-mentioned aims. Naturally, these modifications are also included within the technical scope of the present invention.

[0062] The measurement conditions for each sample are as follows: (1) Biomass degree: Carbon-14 counting, carbon-13 concentration ( １３ C / １２ C), carbon-14 concentration ( １４ C / １２ C) was measured. In the measurement, oxalic acid (HOxII) provided by the National Institute of Standards (NIST) was used as a standard sample. Measurements of this standard sample and a background sample were also carried out simultaneously. Carbon-14 concentration (pMC) refers to the ratio of the carbon-14 concentration of the sample carbon to the standard modern carbon. In accordance with ASTM D6866-21, the carbon-14 concentration (pMC) measured as described above was rounded to two decimal places to determine the biomass-derived carbon concentration. In accordance with ASTM D6866-21, δ １３ C (carbon-13 concentration of sample carbon ( １３ C / １２C) was measured, and the pMC corrected using the deviation from the reference sample expressed in thousandths (‰) was used to calculate the biomass degree using the following formula. The biomass degree (%) value was rounded to one decimal place to form an integer value. The atmospheric correction factor used was the value for 2019-2021 (100.0 pMC) listed in ASTM D6866-21 (latest edition). It is possible that the carbon-14 concentration in the atmosphere will continue to decrease (change). If the atmospheric correction factor value listed in ASTM D6866 (latest edition) is changed from 100.0 pMC in the future, the value listed in ASTM D6866 for the year in which the raw material related to this invention was produced will be used as the atmospheric correction factor. If the production year of the raw material is unknown, the atmospheric correction factor was set to 100.0 pMC. Formula for calculating biomass degree: Biomass degree (%) = (δ １３ pMC of sample corrected by C / atmospheric correction factor) × 100

[0063] (2) Single Yarn Fineness The sample was cut into 100 cm pieces at three different positions in the longitudinal direction, and the weights were measured. The average value was used to determine the yarn fineness. The single yarn fineness (dtex) was calculated from the yarn fineness.

[0064] (3) Tensile Strength and Initial Modulus of Elasticity Using a "Tensilon" manufactured by Orientec Co., Ltd., a strain-stress curve was measured under conditions of a sample length of 200 mm (length between chucks) and an elongation rate of 100% / min at an atmospheric temperature of 20°C and a relative humidity of 65%. The stress at the breaking point was taken as the tensile strength (cN / dtex), and the initial modulus of elasticity (cN / dtex) was calculated from the tangent that gave the maximum gradient near the origin of the curve. Each value was the average of seven measurements.

[0065] (4) Elongation (Creep Resistance) The elongation was measured using Shimadzu Corporation's "EZ Graph" with a sample length of 100 mm and a measurement load of 30% of the tensile strength of the sample. The load was applied to the sample and measured at a set temperature of 25°C until the sample broke. After the measurement, the elongation ε of the sample was calculated from the measurement data. ｉ (t) (unit: %) was calculated using the following formula: ｉ (t) [% unit] = (L(t) - L ０ ) × (100 / L ０ ) In the formula, L０ : Measurement start point (t ０ L(t): Sample length at 100 minutes after the start of the test (t = 100 min)

[0066] (5) Shrinkage The shrinkage was measured in accordance with JIS L1013 8.18.2 Dry Heat Shrinkage (b) method. A fiber sample for measurement was cut to a length of 70 cm, and marks were made 10 cm from each end, with the length between the marks being 50 cm. The fiber sample was placed in a hot air circulating heating oven in a suspended state to prevent the application of any unnecessary load, and heated at 40°C or 120°C for 30 minutes. After heating, the fiber sample was removed from the heating oven and allowed to cool to room temperature. After cooling, the length between the marks on the fiber sample was measured, and the shrinkage was calculated according to the following formula. The shrinkage was measured twice at each temperature, and the average value was used. Formula for calculating shrinkage: Shrinkage (%) = 100 x (length of fiber sample before heating - length of fiber sample after heating) / (length of fiber sample before heating) Where, length of fiber sample before heating: 50 cm, length of fiber sample after heating: measured value

[0067] (6) Weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) The weight average molecular weight (Mw) and number average molecular weight (Mn) of the sample in terms of polystyrene were measured by gel permeation chromatography (GPC), and the molecular weight distribution (Mw / Mn) was calculated. The GPC device used was a Waters GPC 150C ALC / GPC, and the columns used were a Shodex GPC UT802.5 (1 column) and a UT806M (2 columns). The measurement solvent was o-dichlorobenzene, and the column temperature was set to 145 ° C. The sample concentration was 1.0 mg / mL, and 200 μL was injected and measured. A molecular weight calibration curve was created using a polystyrene sample with known molecular weight by the universal calibration method.

[0068] (7) Number of alkyl branches (number of alkyl side chains per 1,000 carbon atoms) 250 mg of a sample was dissolved in o-dichlorobenzene + p-dichlorobenzene-d4 (7:3 vol) at 145°C, and the １３ C-NMR was measured. １３Based on the C-NMR spectrum, the number of alkyl side chains was estimated by the following method. Using the ethylene chain peak (30 ppm) as the reference, the peaks derived from each alkyl side chain were identified as follows: Peak derived from methyl side chain: around 37.5 ppm Peak derived from ethyl side chain: around 34 ppm Peak derived from butyl side chain: around 23.5 ppm When the integral value of the ethylene chain peak is taken as 1,000, Number of methyl side chains = A / 2 (number / 1,000 C) Number of ethyl side chains = B / 2 (number / 1,000 C) Number of butyl side chains = C / 2 (number / 1,000 C) Here, A, B, and C represent the peak integral values ​​at 37.5 ppm, 34 ppm, and 23.5 ppm, respectively.

[0069] (8) Melting Point Measurement was carried out using a differential scanning calorimeter (DSC25) manufactured by TA Instruments. The sample was cut into pieces of 3 to 5 mm or less, and approximately 2 mg of the sample was packed and sealed in an aluminum pan. A similar empty aluminum pan was used as a reference. Under a nitrogen gas atmosphere, the sample was heated from 30°C to 200°C at a heating rate of 5°C / min. The temperature at the top of the obtained endothermic peak was taken as the melting point. The melting point was measured twice, and the average value was used.

[0070] (9) Coop Index (Cut Resistance) Measurement was carried out using a Coop Tester (manufactured by Sodimat) based on the European Standard EN 388. Test Method: Aluminum foil was placed on a sample stage, and a sample (polyethylene fiber) with a basis weight of approximately 350 g / m was placed on top of the aluminum foil. ２ A knitted fabric sample (6 cm x 10 cm) was placed on the machine. The circular blade was then rotated in the opposite direction to the running direction and run over the cotton cloth. After the cotton cloth was cut, the circular blade came into contact with the aluminum foil, detecting the passage of electricity. The rotation of the circular blade then stopped, and the test was completed. The number of times the circular blade reciprocated was recorded by the counter of the machine.

[0071] In this test, the basis weight was about 300 g / m ２The cut resistance level of the knitted fabric samples was evaluated using a cotton fabric (cotton) as a blank. The test started with the blank, and the blank test and the knitted fabric sample test were conducted alternately. The knitted fabric sample was tested five times, and finally the blank test was conducted a sixth time. This test was conducted five times, and the average index value of the five sets was used as the cut resistance evaluation value. The higher the index value, the better the cut resistance.

[0072] The index value was calculated using the following formulas: A = (count value of knitted sample (or blank cotton fabric) before test + count value of knitted sample (or blank cotton fabric) after test) / 2 Index value = (count value of knitted sample (or blank cotton fabric) + A) / A The cutter used to evaluate cut resistance was an L-type rotary cutter (φ45 mm) manufactured by OLFA Corporation, made of SKS-7 tungsten steel, with a blade thickness of 0.3 mm. The load during the test was 3.14 N (320 gf).

[0073] (10) Coolness to the touch (Q-max) Measurements were performed using a KES-F7 (Thermo Labo II) device based on JIS L1927. The environmental conditions around the measurement device were set to room temperature of 20°C ± 2°C, relative humidity (RH) of 65% ± 4%, and the temperature of the measurement table of 20°C ± 2°C. In the measurement, heat was first supplied by contacting the heat supply device with the heat source plate, and the temperature of the heat source plate was set to 30.0°C (temperature difference ΔT = 10°C with the knitted sample). Next, a 15cm x 15cm knitted sample (made of polyethylene fiber) adjusted to 20°C ± 2°C was placed on the measurement table. Then, the heat source plate and the heat supply device were separated, and the measurement section was kept horizontal with the heat supply stopped, and the measurement section was quickly brought into contact with the knitted sample at a pressure of 1.02 kPa. After contact, the initial temperature change of the heat source plate was measured for approximately 5 seconds. From the measurement results, the heat flux q(t) was calculated using the following formulas (1) and (2), and the maximum value q(t) (= Q ｍａｘ ) was calculated. Each value was the average of five measurements. Equation (1): T(t) = T ｐ０ -T ｐ (t) Formula (2): q(t)=[(M×C) / A]×[dT(t) / dt] In the formula, q(t): Heat flux (W / cm２ ) A: Area of ​​heat source plate (cm ２ ) M: Mass of heat source plate (kg) C: Specific heat of heat source plate [J / (kg K)] T ｐ０ : Initial temperature of the heat source plate (℃) T ｐ (t): Temperature of the heat source plate after t seconds of contact (°C) T(t): Temperature drop of the heat source plate (°C)

[0074] (11) Thermal Conductivity Measurements were performed using a KES-F7 (Thermo Labo II) device. The environmental conditions around the measurement device were set to room temperature of 20°C ± 2°C, relative humidity (RH) of 65% ± 4%, and the temperature of the measurement table of 20°C ± 2°C. For the measurement, first, heat was supplied by contacting a heat supply device with the heat source plate, and the temperature of the heat source plate was set to 30.0°C (temperature difference ΔT = 10°C with the knitted sample). Next, a 15 cm x 15 cm knitted sample (made of polyethylene fiber) adjusted to 20°C ± 2°C was placed on the measurement table, and the heat source plate was placed on top of it. After 10 minutes, the power consumption of the heat source plate was measured, and the thermal conductivity K was calculated using the following formula. Each value was the average of five measurements. K = (W x D) / (A x ΔT) where K: thermal conductivity (W / m K) D: thickness of fabric sample (m) A: contact area of ​​heat source plate (0.0025 m ２ ) ΔT: Temperature difference between both sides of the fabric sample (10°C) W: Heat flow loss (W watts)

[0075] Example 1 Polyethylene resin A having a biomass content of 98% and a molecular weight distribution (Mw / Mn) of 6.5 and polyethylene resin B having a molecular weight distribution of 3.5 were dry blended in a ratio of 4:6 to produce a blend polymer with a melting point of 130°C. This blend polymer was extruded using a φ0.9 mm, 180H spinneret at 280°C and a single-hole throughput of 0.35 g / min. The extruded filament passed through a 7 cm heat-retention zone and then cooled at 20°C with quench air at 0.5 m / s, ultimately lowering the temperature to 20°C. The resulting fibrous material was wound at a speed of 300 m / min to produce a polyethylene fibrous material (undrawn yarn). Next, this undrawn yarn was drawn using multiple temperature-controllable rollers. The first drawing (primary drawing) was carried out at 55°C at a draw ratio of 2.5, and then the fiber was heated to 100°C and drawn to a total draw ratio of 10.0. The physical properties of the obtained polyethylene fiber (drawn yarn) are shown in Table 1.

[0076] Example 2 A high-performance polyethylene fiber (drawn yarn) was produced under the same conditions as in Example 1, except that the winding speed was changed to 350 m / min and the draw ratio was adjusted to 8.5 times.

[0077] Example 3 A high-performance polyethylene fiber (drawn yarn) was produced under the same conditions as in Example 1, except that a blend polymer was used, which was a dry blend of polyethylene resin A having a biomass content of 98% and a molecular weight distribution (Mw / Mn) of 6.5 and polyethylene resin B having a molecular weight distribution of 3.5, in a ratio of 6:4.

[0078] Example 4 A high-performance polyethylene fiber (drawn yarn) was produced under the same conditions as in Example 1, except that a blend polymer was used, which was a dry blend of polyethylene resin A having a biomass content of 98% and a molecular weight distribution (Mw / Mn) of 6.5 and polyethylene resin B having a molecular weight distribution of 3.5, in a ratio of 8:2.

[0079] Comparative Example 1 A high-performance polyethylene fiber (drawn yarn) was produced using only polyethylene resin A having a biomass content of 98% and a molecular weight distribution (Mw / Mn) of 6.5, with the other conditions being the same as in Example 1. In this Comparative Example 1, although it was possible to obtain yarn, frequent yarn breakage occurred, resulting in a significant decrease in productivity.

[0080] Comparative Example 2 High-performance polyethylene fibers (drawn yarns) were produced under the same conditions as in Example 1, except that only polyethylene resin B having a molecular weight distribution (Mw / Mn) of 3.5 was used.

[0081]

[0082] The high-performance polyethylene fiber of the present invention has excellent mechanical properties even when it contains biomass-derived raw materials. Furthermore, the high-performance polyethylene fiber in a preferred embodiment of the present invention has excellent mechanical properties, high dimensional stability at actual use temperatures, and exhibits excellent high shrinkage and high shrinkage stress at appropriate temperatures without impairing the mechanical properties of polyethylene, thereby fully functioning. Cord-like products, woven and knitted fabrics, gloves, and ropes made from the high-performance polyethylene fiber of the present invention have excellent cut resistance. Therefore, they exhibit high performance in applications such as butcher strings, safety gloves, safety ropes, and finishing ropes. Furthermore, the high-shrinkage polyethylene fiber of the present invention can be used not only for the above-mentioned molded products but also as highly shrinkable fabrics and tapes, and can be applied to a wide range of applications such as industrial materials and packaging materials. Furthermore, it exhibits excellent performance as a medical fiber, such as medical sutures, artificial tendons, and artificial muscles. By using the production method of the present invention, high-performance polyethylene fibers satisfying these properties can be efficiently produced.

Claims

1. High-performance polyethylene fiber that has been analyzed by radiocarbon ( １４ C) A high-performance polyethylene fiber comprising: a polyethylene resin A having a biomass degree calculated by measurement of 1% or more and an Mw / Mn of 3 or more; and a polyethylene resin B having an Mw / Mn of 6 or less, wherein the proportion of the polyethylene resin A is 20 to 90% by mass based on a total of 100% by mass of the polyethylene resin A and the polyethylene resin B.

2. The high-performance polyethylene fiber according to claim 1, having a tensile strength of 8 cN / dtex or more and an initial modulus of elasticity of 200 cN / dtex or more.

3. The high-performance polyethylene fiber according to claim 1, wherein the elongation of the polyethylene fiber calculated by the following formula is 25% or less. Elongation = [(L(t) - L ０ ) / L ０ ]×(100) where L ０ is the length of the polyethylene fiber before the start of measurement; L(t) is the length of the polyethylene fiber 100 minutes after the start of elongation measurement under the load when the tensile strength (cN / dtex) of the polyethylene fiber becomes 30%, which is the set load.

4. High-performance polyethylene fiber according to claim 1, wherein the shrinkage rate of the polyethylene fiber according to JIS L1013 satisfies the following (1) and (2): (1) the shrinkage rate measured when the polyethylene fiber is heated at 40°C for 30 minutes and then allowed to cool is 0.8% or less, and (2) the shrinkage rate measured when the polyethylene fiber is heated at 120°C for 30 minutes and then allowed to cool is 6% or more.

5. The high-performance polyethylene fiber according to claim 1, wherein the single fiber fineness is 0.5 to 10 dtex.

6. The high-performance polyethylene fiber according to claim 1, wherein the weight-average molecular weight of the polyethylene fiber is 70,000 to 1,000,000, and the Mw / Mn ratio is 10 or less.

7. High-performance polyethylene fiber according to claim 1, which contains at least one alkyl side chain selected from the group consisting of methyl, ethyl, and butyl groups, and has 0.3 or more alkyl side chains per 1,000 carbon atoms.

8. High-performance polyethylene fiber according to claim 1, which has a coupe tester index value of 4.0 or more as measured in accordance with European Standard EN388.

9. The cool-to-the-touch value measured based on JIS L1927 is 0.1 W / cm ２ The high-performance polyethylene fiber according to claim 1, wherein the fiber is a polyethylene fiber having the above properties.

10. High-performance polyethylene fiber according to claim 1, which has a thermal conductivity of 0.05 to 0.40 W / (m·K) when measured by bringing the polyethylene fiber at 20°C into contact with a heat source plate at 30.0°C.

11. The high-performance polyethylene fiber according to claim 1, wherein the value obtained by dividing the molecular weight distribution (Mw / Mn) of the polyethylene resin A by the molecular weight distribution of the polyethylene resin B ([Mw / Mn of polyethylene resin A] / [Mw / Mn of polyethylene resin B]) is 1.3 to 4.

0.

12. The high-performance polyethylene fiber according to claim 1, further comprising a resin other than the polyethylene resin A and the polyethylene resin B.

13. The high-performance polyethylene fiber according to claim 12, wherein the other resin is a polyethylene resin other than the polyethylene resin A and the polyethylene resin B.

14. The high-performance polyethylene fiber according to claim 1, which essentially consists of the polyethylene fiber A and the polyethylene fiber B.

15. An article comprising the high-performance polyethylene fiber of any one of claims 1 to 14.

16. Radiocarbon ( １４ C) A method for producing a high-performance polyethylene fiber, comprising: a step of mixing polyethylene resin A, which has a biomass degree of 1% or more as calculated by measurement and an Mw / Mn of 3 or more, with polyethylene resin B, which has an Mw / Mn of 6 or less, and melt-extruding the resulting resin mixture at a temperature 10°C or more higher than the melting point of the resulting resin mixture; a spinning step of supplying the melt-extruded resin mixture to a spinning nozzle at a temperature 80°C or more higher than the melting point of the resin mixture; a step of cooling the fibrous material obtained by discharging from the spinning nozzle and then winding it up at 25 m / min or more; and a drawing step of drawing the fibrous material at a temperature not higher than the melting point of the resulting fibrous material at least once or more times to a draw ratio of 5 times or more, wherein the ratio of the deformation in the spinning step to the deformation in the drawing step (deformation in the spinning step / deformation in the drawing step) is 100 or less.

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