JP7306375B2 - Polyethylene fiber and products using it - Google Patents

Description

TECHNICAL FIELD The present invention relates to high-strength polyethylene fibers having excellent mechanical properties such as tensile strength and elongation at break, and particularly excellent dimensional stability, and products using the same.

With regard to high-strength polyethylene fibers, it is known that unprecedented high-strength and high-elasticity fibers can be obtained by using ultra-high molecular weight polyethylene as a raw material and using the so-called "gel spinning method". It is widely used in industries such as ropes (for example, Patent Literature 1 and Patent Literature 2). When trying to use such high-strength, high-modulus, high-strength polyethylene fibers for long-term applications, there are drawbacks that hinder them. This drawback is related to the creep properties, and creep rupture occurs in long-term loading applications. In previous investigations, attempts have been made to improve creep properties under load by introducing branches into polyethylene fiber raw materials (eg, Patent Documents 3 and 4).

Japanese Patent Publication No. 55-107506 Japanese Patent Publication No. 60-075607 Japanese Patent Publication No. 64-38439 Japanese Patent Publication No. 6-280111

However, although improvement in creep properties can be obtained only by using a raw material that introduces branching, it may adversely affect the final mechanical properties of the fiber, and furthermore, creep elongation at the initial stage immediately after application of a load is reduced. It was confirmed that there was no improvement.

The present invention has been made in view of the above problems, and an object of the present invention is to provide polyethylene in which initial elongation immediately after application of a load is improved while ensuring high strength and high elastic modulus characteristics as a high strength polyethylene fiber. It is to provide fiber.

In order to solve the above problems, the present inventors have reached the following invention as a result of earnest research.

(1) Intrinsic viscosity [η] of 5.0 dL/g or more and 40.0 dL/g or less, 90% or more of the repeating units are ethylene, and 0.1 or more and 10.0 per 1000 carbon atoms A polyethylene fiber having the following alkyl side chain, wherein the organic silane compound in the fiber is 0.1% by mass or more and 5.0% by mass or less.
(2) In creep measurement at a measurement temperature of 70°C and a measurement load of 20%, the creep rate at an elapsed time of 1 minute is 2.5 × 10 ^-4 /sec or less, and the elongation is 3.0%. The polyethylene fiber according to (1), which has a creep rate of 1.0×10 ⁻⁵ /sec or less when reaching .
(3) The polyethylene fiber according to (2), which has a creep life of 50 hours or more.
(4) The polyethylene fiber according to any one of (1) to (3), wherein the alkyl side chain contains at least one of methyl, ethyl and butyl groups.
(5) The polyethylene fiber according to any one of (1) to (4), which has a tensile strength of 25 cN/dtex or more and an initial elastic modulus of 900 cN/dtex or more.
(6) A product comprising the polyethylene fiber according to any one of (1) to (5).
(7) The product of (6), which is a braid, twisted line, fishing line, rope, or net.

According to the present invention, compared with conventional high-strength polyethylene fibers, polyethylene fibers exhibiting small elongation at the beginning of load application in terms of creep properties and excellent final creep life, and products using the same are provided. can be done.

FIG. 4 is a graph showing the creep rate versus elapsed measurement time when creep measurement is performed on polyethylene fibers of Examples and Comparative Examples. FIG. 2 is a graph showing creep rate versus elongation when creep measurement is performed on polyethylene fibers of Examples and Comparative Examples. FIG. 2 is a graph showing the creep rate versus the measured elapsed time in the time until rupture (creep life) when the polyethylene fibers of Examples and Comparative Examples are subjected to creep measurement.

Hereinafter, the polyethylene fiber of the present invention and products using the same will be described. However, the present invention is not limited to the following, and it is of course possible to implement it by making appropriate changes within the scope that can be adapted to the gist of the above and below, all of which are within the technical scope of the present invention. subsumed in

The polyethylene fiber of the present invention is composed of ethylene having a limiting viscosity [η] of 5.0 dL/g or more and 40.0 dL/g or less and a repeating unit of 90% or more, and has a repeating unit of 0.1 or more and 10 per 1000 carbon atoms. The polyethylene fiber has 0 or less alkyl side chains, and the organic silane compound in the fiber is 0.1% by mass or more and 5.0% by mass or less.

It is preferable to use ultra-high molecular weight polyethylene as the raw material polyethylene for the polyethylene fiber of the present invention. The intrinsic viscosity [η] of such polyethylene is 5.0 gL/g or more and 40.0 dL/g or less. It is preferably 8.0 gL/g or more and 35.0 gL/g or less, more preferably 10.0 gL/g or more and 30.0 gL/g or less. If the intrinsic viscosity is less than 5.0 dL/g, the tensile strength of the final polyethylene fiber will be low, and a high strength fiber exceeding the desired strength (for example, 15 cN/dtex or more) may not be obtained. On the other hand, if the intrinsic viscosity is higher than 40.0 dL/g, the processability may be lowered and fiberization may become difficult.

In the raw material polyethylene of the polyethylene fiber of the present invention, 90 mol % or more of the repeating units are ethylene. The repeating unit of ethylene is preferably 92 mol % or more, more preferably 94 mol % or more, and most preferably an ethylene homopolymer. The raw material polyethylene may contain components other than ethylene as long as they do not adversely affect the physical properties of the polyethylene fiber. For example, raw polyethylene is a copolymer of ethylene and a small amount of other monomers, specifically other monomers such as α-olefin, acrylic acid and its derivatives, methacrylic acid and its derivatives, vinylsilane and its derivatives, and ethylene. can be used as

In addition, the polyethylene fiber of the present invention has 0.1 to 10.0 alkyl side chains per 1000 carbon atoms. More preferably 0.2 or more and 9.0 or less, still more preferably 0.3 or more and 8.0 or less. If the number of alkyl side chains is less than 0.1 per 1,000 carbon atoms, the effect of improving the creep properties is very small, and the dimensional stability is poor, which is undesirable. Conversely, if the number of alkyl side chains is more than 10.0 per 1000 carbon atoms, the spinnability and drawability will be hindered, and the spinnability will be remarkably lowered. This alkyl side chain is preferably at least one of methyl group, ethyl group and butyl group. However, it may be other than those defined in these.

The inventors have found that the inclusion of an organosilane compound in polyethylene fibers leads to a significant improvement in creep properties. Therefore, the polyethylene fiber of the present invention contains 0.1% by mass or more and 5.0% by mass or less of an organic silane compound in the fiber. The content is more preferably 0.2% by mass or more and 4.0% by mass or less, still more preferably 0.3% by mass or more and 3.0% by mass or less. If the content of the organic silane compound in the fiber is less than 0.1% by mass, it is difficult to obtain the effect of improving the dimensional stability. If it is more than 5.0% by mass, it may hinder the spinnability and drawability, resulting in remarkably low spinnability.

Examples of organic silane compounds include, but are not limited to, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrismethoxyethoxysilane, and trimethylvinylsilane.

Further, in the polyethylene fiber of the present invention, when the number of alkyl side chains is (a) and the mass % of the organosilane compound is (b), the multiplied number (c = a x b) is 0.22. It can be seen from the examples described later that the dimensional stability in the initial stage is particularly excellent by exceeding .

The polyethylene fiber of the present invention preferably has a creep rate of 2.5×10 ⁻⁴ /sec or less in a measurement elapsed time of 1 minute in creep measurement at a measurement temperature of 70° C. and a measurement load of 20% at breaking load. More preferably, it is 2.3×10 ⁻⁴ /sec or less. Also, the creep rate when the elongation reaches 3.0% is preferably 1.0×10 ⁻⁵ /sec or less. More preferably, it is 0.9×10 ⁻⁵ /sec or less. If the creep rate is greater than 2.5×10 ⁻⁴ /sec at an elapsed measurement time of 1 minute, the elongation increases when a load is applied, which is not preferable from the viewpoint of dimensional stability. Also, if the creep rate when the elongation reaches 3.0% is greater than 1.5×10 ⁻⁵ /sec, the elongation increases when a load is applied, which is not preferable from the viewpoint of dimensional stability. .

Furthermore, the polyethylene fiber of the present invention preferably has a creep life of 50 hours or more, more preferably 70 hours or more. With a creep life of 50 hours or more, the polyethylene fiber of the present invention has excellent creep properties. As for the mechanical properties of the polyethylene fiber of the present invention, the tensile strength is preferably 15 cN/dtex or more, more preferably 18 cN/dtex or more, still more preferably 20 cN/dtex or more. The polyethylene fiber of the present invention preferably has an initial elastic modulus of 900 cN/dtex or more, more preferably 1100 cN/dtex or more, and even more preferably 1200 cN/dtex or more. Polyethylene fibers with such mechanical properties are expected to be used in applications that take advantage of the characteristics of conventional high-strength polyethylene fibers with high strength and high elastic modulus.

As a manufacturing method for obtaining the polyethylene fiber of the present invention, it is preferable to employ a gel spinning method. Specifically, the method for producing a polyethylene fiber of the present invention includes a dissolving step of dissolving polyethylene in a solvent to obtain a polyethylene solution, and discharging the polyethylene solution from a nozzle at a temperature equal to or higher than the melting point of the polyethylene, and discharging the discharged yarn. It is preferable to include a spinning step of cooling the filament with a coolant, a drying step of removing the solvent from the discharged undrawn yarn, a drawing step of drawing, and a step of winding the drawn drawn yarn. Each step will be described below.

<Dissolution process>
In the preferred manufacture of the polyethylene fibers of the present invention, a polyethylene solution is prepared by dissolving high molecular weight polyethylene in a solvent. Examples of solvents for polyethylene include volatile organic solvents such as decalin and tetralin, and non-volatile solvents such as paraffin. In addition, it is convenient to incorporate the organosilane compound into the spinning solution in order to include the organosilane compound within the fiber. However, the method of introducing the silane compound into the fiber is not limited to this.

The concentration of polyethylene in the polyethylene solution is preferably 0.5% by mass or more and 40% by mass or less, more preferably 2.0% by mass or more and 30% by mass or less, still more preferably 3.0% by mass or more and 20% by mass. It is below. If the concentration of polyethylene is 0.5% by mass or less, the production efficiency may be very poor. On the other hand, if the concentration of polyethylene exceeds 30% by mass, it may become difficult to discharge from a nozzle described later in the gel spinning method due to the extremely high molecular weight.

<Spinning process>
The polyethylene solution described above is extruded using an extruder or the like at a temperature higher than the melting point of polyethylene by 10°C or higher, more preferably at a temperature higher than 20°C or higher, still more preferably at a temperature higher than 30°C or higher, and a constant supply device is used. and supplied to the spinning nozzle (spinneret). After that, the polyethylene solution is passed through a spinneret in which a plurality of orifices are arranged to form threads. The temperature of the spinneret must be higher than the melting temperature of polyethylene, preferably 140° C. or higher, more preferably 150° C. or higher, and lower than the thermal decomposition temperature of polyethylene. The diameter of the orifice is preferably 0.2 to 3.5 mm, more preferably 0.5 to 2.5 mm.

Next, the ejected gel thread is collected while being cooled with a cooling medium. At this time, the take-up speed is preferably 800 m/min or less, more preferably 200 m/min or less. If the take-up speed is faster than 800 m/min, the yarn may easily break. The cooling method may be, for example, a dry quenching method using an inert gas such as air or nitrogen, or a cooling method using a miscible liquid or an immiscible liquid such as water. In the production method of the present invention, it is preferable to rapidly and uniformly cool the gel filament discharged from the spinning nozzle. Therefore, the cooling method using water is preferred. Also, the temperature of the liquid is preferably -10 to 60°C.

<Drying/stretching process>
The filamentous (undrawn filament) taken in the spinning step is continuously or temporarily wound, and then dried and drawn. The purpose of the drying step is to remove the solvent, and as means for removing the solvent, in the case of a volatile solvent, the solvent may be removed in a heating medium atmosphere or using a heating roller. Examples of the medium include air, inert gas such as nitrogen, water vapor, liquid medium, and the like. When a non-volatile solvent is used, a method of extraction using an extractant or the like can be used. As extractants, chloroform, benzene, hexane, heptane, nonane, decane, ethanol, higher alcohols and the like can be used.

In the subsequent drawing step, the undrawn yarn is drawn several times while being heated. The stretching may be carried out once or in a plurality of times, but the stretching is preferably 1 time or more and 3 times or less. The stretching step may be performed in a heat medium atmosphere or may be performed using a heating roller. Examples of the medium include air, inert gas such as nitrogen, water vapor, liquid medium, and the like.

The drying and stretching steps described above may be carried out separately. The draw ratio of the undrawn yarn is preferably 1.5 times or more and 60 times or less, more preferably 3.0 times or more and 50 times, regardless of whether the drawing process is a single stage or a multi-stage drawing process. It is below. If the draw ratio is lower than 1.5 times, the tensile strength of the obtained polyethylene fiber will be lower than the above value. Moreover, when the draw ratio exceeds 60 times, it is technically and industrially difficult. Moreover, it is preferable to stretch|stretch at high temperature below the melting|fusing point of polyethylene. When stretching is performed multiple times, the temperature during stretching is preferably increased in the subsequent stages, and the stretching temperature in the final stage of stretching is preferably 80°C or higher and 170°C or lower, more preferably 90°C or higher and 160°C. It is below. The drawing time of the undrawn yarn, that is, the time required for deformation of the multifilament is preferably 0.5 minutes or more and 20 minutes or less, more preferably 15 minutes or less, and still more preferably 10 minutes or less. If the deformation time of the multifilament exceeds 20 minutes, the molecular chains are relaxed during drawing, and the strength of the single filament is lowered, which is not preferable.

<Winding process>
The drawn multifilament (polyethylene fiber) is preferably wound up within 10 minutes from the end of drawing. Further, the drawn yarn is preferably wound with a tension of 0.001 cN/dtex or more and 5 cN/dtex or less. By winding the multifilament within the above range, it is possible to wind the multifilament while maintaining the residual strain in the cross-sectional direction. If the tension during winding is less than 0.001 cN/dtex, the residual strain becomes small and the stress distribution in the cross-sectional direction becomes unstable. A difference in residual strain appears between Further, when the winding tension is higher than 5 cN/dtex, the single filaments constituting the multifilament are likely to break.

<Others>
In order to impart other functions to the polyethylene fiber of the present invention, additives such as antioxidants and anti-reduction agents, pH adjusters, surface tension reducing agents, thickeners, humectants, and thick dyeing agents may be added during the above process. Agents, preservatives, antistatic agents, pigments, mineral fibers, other organic fibers, metal fibers, sequestering agents and the like may be added.

The polyethylene fiber of the present invention can be used, for example, in braided cords, twisted yarns, fishing lines, ropes for ships (mooring ropes, tag lines, etc.), fisheries, agriculture, mountaineering, civil engineering, electrical facilities, various ropes for construction work, and the like. can be used for the products of Therefore, these products are also included in the scope of the present invention.

EXAMPLES The present invention will be described below using examples. However, the invention is not limited to the following examples.

The physical properties of the polyethylene fibers obtained in Examples and Comparative Examples to be described later were measured by the following measurement and test methods, and performance was evaluated.

(1) Intrinsic viscosity Using an Ubbelohde-type capillary viscosity tube, the specific viscosity of various dilute solutions in decalin at 135°C is measured, the viscosity is plotted against the concentration, and the origin of the straight line obtained by least-squares approximation is obtained. The intrinsic viscosity was determined from the extrapolation point of . 1% by mass of an antioxidant ("Yoshinox (registered trademark) BHT" manufactured by API Corporation) was added to the sample, and stirred and dissolved at 135°C for 4 hours to prepare a measurement solution.

(2) Branching amount 250 mg of each sample was dissolved in o-dichlorobenzene + p-dichlorobenzene-d4 (7 + 3 vol) at 145 ° C., C-NMR was measured at 120 ° C., and the following procedure was performed from the obtained 13C-NMR spectrum. Estimated at
When the ethylene chain peak of polyethylene is 30 ppm, the peak derived from methyl branching is detected around 37.5 ppm, the peak derived from ethyl branching is detected around 34 ppm, and the peak derived from butyl branching is detected around 23.5 ppm. When the integral value of the ethylene chain peak is 1000, the peak integral value of 37.5 ppm is A, the peak integral value of 34 ppm is B, and the peak integral value of 23.5 ppm is C, the amount of methyl branching is A / 2 (number/1000C), the amount of ethyl branching can be calculated as B/2 (number/1000C), and the amount of butyl branching can be calculated as C/2 (number/1000C).

(3) Amount of Organosilane Compound Contained in Fiber About 0.1 g of a sample was collected, and 1 ml of hydrochloric acid, 1 ml of hydrofluoric acid, and 5 ml of nitric acid were added, and the sample was subjected to lamp 10 using a microwave sample pretreatment device (Multiwave PRO manufactured by Anton Paar). After dissolving the sample in acid under the conditions of 900W and hold for 20 minutes, the volume was adjusted to 20 ml with water. After diluting this sample solution twice with water, it was measured with an ICP emission spectrometer (SUPECTRO BLUE TI manufactured by SUPECTRO) with a plasma output of 1400 W, a plasma gas flow of 13.0 L/min, an auxiliary gas of 1.0 L/min, and a nebulizer. Si was quantified under the condition of a gas flow of 0.80 L/min. A calibration curve was prepared at Si standard solution concentrations of 0, 2.5, 5.0, and 15.0 mg/L, and Si was quantified at a Si measurement wavelength of 251.612 nm.

(4) Fineness Samples were cut into 10 m lengths at five different positions, their weights were measured, and the fineness (dtex) was determined using the average value.

(5) Tensile strength/elongation at break/initial elastic modulus Measured according to JIS L1013 8.5.1. Using Orientec's "Tensilon", the strain-stress curve was obtained under the conditions of a sample length of 200 mm (length between chucks), an elongation speed of 100 mm / min, an ambient temperature of 20 ° C., and a relative humidity of 65%. The tensile strength (cN/dtex) was calculated from the stress at the breaking point, the elongation at break was calculated from the elongation, and the elastic modulus (cN/dtex) was calculated from the tangent line giving the maximum gradient near the origin of the curve. In addition, the number of times of measurement was set to 10, and the average value was shown. The initial load applied to the sample during measurement was 1/10 of the mass (g) per 10,000 m of the sample.

(6) Creep Measurement The creep rate, which represents creep elongation, is determined by the method described in Journal Polymer Science, 22, 561 (1984). The creep measurement in this specification is performed using a dynamic viscoelasticity measuring device (DMA-Q800, manufactured by TA Instruments Japan) in the measurement mode Creep Stress, with a sample length of 10 mm. , the measurement temperature was 70° C., and the applied load was 20% of the breaking load. The measurement was continued until rupture, and each sample was evaluated for creep rate at 1 minute elapsed time, creep rate when elongation reached 3.0%, and time until rupture (creep life).

(Example 1)
Ultra high molecular weight polyethylene having an intrinsic viscosity of 18.6 dl/g and having 0.5 ethyl branches per 1000 carbon atoms, vinyltriethoxysilane and decahydronaphthalene (decalin) in a weight ratio of 10.5:0.3:89. .2 to form a liquid slurry. The material was melted in a twin-screw extruder equipped with a mixing and conveying section, and the resulting polyethylene solution was extruded through a spinneret at a spinneret surface temperature of 175° C. and a single hole throughput of 1.5 g/min. The number of orifices formed in the spinneret was 32 and the orifice diameter was 0.8 mm. While the extruded filament was taken up, the filament was cooled while being taken up in a water-cooled bath at 20°C at a speed of 60.0 m/min to obtain an undrawn yarn (undrawn multifilament) consisting of 32 single filaments.

Next, the unstretched multifilament was stretched 1.5 times while being dried with hot air at 110°C, and then stretched 2.0 times with hot air at 140°C. A multifilament was obtained by setting the total draw ratio to 3.0 times. The resulting multifilament was stretched 3.0 times with hot air at 150°C, and the stretched multifilament was immediately wound up in the stretched state. Table 1 and FIGS.

FIG. 1 shows the creep rate with respect to the measurement elapsed time when the creep measurement was performed. FIG. 2 shows creep rate versus elongation when creep measurement was performed. FIG. 3 shows the creep rate with respect to the measured elapsed time in creep measurement in the time until rupture (creep life).

(Comparative example 1)
In Example 1, the ultra-high molecular weight polyethylene having an intrinsic viscosity of 17.5 dl/g and having 0.5 methyl branches per 1000 carbon atoms was used, and the weight ratio of ultra-high molecular weight polyethylene to vinyltriethoxysilane was changed to 9.5. A drawn multifilament was obtained in the same manner as in Example 1, except that the ratio was changed to 0:0.3:90.7. Table 1 and FIGS.
(Comparative example 2)
Vinyltriethoxysilane was removed from Example 1, and the weight ratio of ultra-high molecular weight polyethylene and decalin was changed to 10.5:89.5. A drawn multifilament was obtained in the same manner as in Example 1, except for the above. Table 1 and FIGS.

(Comparative Example 3)
In Example 1, the vinyltriethoxysilane was removed, the intrinsic viscosity was 19.0 dl/g, the ultra-high molecular weight polyethylene without branching was used, and the weight ratio of the ultra-high molecular weight polyethylene and decalin was changed to 9.0:91.0. A drawn multifilament was obtained in the same manner as in Example 1, except that the obtained multifilament was drawn 3.7 times with hot air at 150°C. Table 1 and FIGS.

(Comparative Example 4)
The procedure of Example 1 was repeated except that the ultra-high molecular weight polyethylene having an intrinsic viscosity of 17.0 dl/g and having 11.0 methyl branches per 1000 carbon atoms was used. However, the multifilament could not be collected due to frequent yarn breakage in the spinning process.

(Comparative Example 5)
Example 1 was repeated except that ultra-high molecular weight polyethylene, vinyltriethoxysilane and decalin were mixed in a weight ratio of 10.5:3.6:85.9 to form a liquid slurry. . However, the multifilament could not be collected due to frequent yarn breakage in the spinning process. An analysis result of the sample with broken threads showed that the organic silane compound contained in the fibers was 5.8% by mass.

(Discussion)
Compared with Example 1, in Comparative Examples 1 to 3, the number of branches of the ultra-high molecular weight polyethylene and the mass number of the organic silane compound in the fiber are not the predetermined amounts, or there is no organic silane compound, or the ultra-high molecular weight polyethylene is branched. , the creep property of the obtained multifilament was inferior. Moreover, in Comparative Examples 4 and 5, no multifilament was obtained.

The polyethylene fiber of the present invention can be used, for example, for fishing lines, ships (mooring ropes, tag lines, etc.), fisheries ropes, various agricultural ropes, mountaineering ropes, various ropes for civil engineering, electrical facilities, and construction work, nets, and the like. be. As described above, the polyethylene fiber of the present invention can exhibit excellent performance and can be widely applied, so that it can greatly contribute to the industrial world.

Claims (3)

Intrinsic viscosity [η] of 10.0 dL/g or more and 30.0 dL/g or less, 94% or more of the repeating unit is ethylene, and 0.3 or more and 8.0 or less ethyl per 1000 carbon atoms It is a polyethylene fiber having a group, and vinyltriethoxysilane in the fiber is 0.3% by mass or more and 3.0% by mass or less,
In creep measurement at a measurement temperature of 70°C and a measurement load of 20%, the creep rate at an elapsed time of 1 minute is 2.5 × 10 ^-4 /sec or less, and the elongation reaches 3.0%. a creep rate of 1.0×10 ⁻⁵ /sec or less and a creep life of 50 hours or more;
A polyethylene fiber characterized by having a tensile strength of 25 cN/dtex or more and an initial elastic modulus of 900 cN/dtex or more. A product comprising the polyethylene fibers of claim 1. 3. The article of claim 2, which is a braid, strand, fishing line, rope, or net.

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