JP2006342442A - Rope made of high-tenacity polyethylene fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide rope comprising new high-tenacity polyethylene fibers uniform in the fibers' internal structure and slight in tenacity variation of the filaments constituting the fibers. <P>SOLUTION: The rope comprises high-tenacity polyethylene fibers ≤9 nm in monoclinic-derived crystalline size. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a rope comprising high strength polyethylene fibers.
More specifically, the present invention relates to a rope using a novel polyethylene fiber having high strength, a uniform fiber internal structure, and less variation in the strength of the filament constituting the fiber.

With regard to high-strength polyethylene fibers, it is known that ultra-high molecular weight polyethylene is used as a raw material, and so-called “gel spinning” can produce unprecedented high-strength and high-modulus fibers, which are already widely used in industry. (For example, Patent Document 1 and Patent Document 2).

Japanese Patent Publication No. 60-47922 Japanese Patent Publication No. 64-8732

  Ultra high molecular weight polyethylene fibers are used in various applications and are used to reinforce concrete and mortar (for example, Patent Document 3).

JP 2004-285557 A

  The strength of the rope is highly correlated with the strength of the fiber. However, when the rope is actually used, a process called eye processing is performed on both ends of the rope, but the portion where the rope is most easily broken is a portion subjected to the eye processing. In particular, in the case of a rope using high strength fibers, if it is curved and a load is applied from both ends thereof, it tends to break and the residual strength with respect to tensile strength tends to be very low. The tensile strength in such a curved shape is considered to be largely influenced by the elongation of the fiber, but the thickness variation of the single yarn fineness is also considered to be one of the factors that affect the tensile strength. When a tensile load is applied in a curved shape, a load is applied from the fiber of the outermost layer part of the curved part, and if the thickness variation of the single yarn fineness is large, it is easy to break from a thin fiber, and breaks from a thin fiber one after another The strength value is expected to decrease. Therefore, in order to obtain a high strength rope, it is considered essential to modify the fiber. In particular, in the case of a rope, it is considered that it is important to improve the tensile breaking strength in a curved state because the end is subjected to eye processing. In addition, when used as a mooring rope, the bending wear strength is important because it is subjected to a tensile action while being bent at various points. The same part of the rope is rubbed by bending. For this reason, if the variation in the fineness of the fibers is large, the thin fibers are prematurely broken, and as a result, the residual strength of the rope due to bending wear is considered to decrease.

  An effective means to satisfy these broad requirements is to minimize the number of defects present in the interior of the fiber. In addition, the filaments constituting the fibers are uniform. In the conventional gel spinning method, this internal defect structure was not suppressed to a sufficiently low level. Further, the variation in the strength of each filament constituting the fiber was also large. The present inventors consider these causes as follows.

  When the conventional gel spinning method is used, super-stretching operation becomes possible, high strength and high elastic modulus are achieved, and the resulting fiber structure has a long-period structure observed in small-angle X-ray scattering measurement. Crystallization and ordering is so high that it is not done. On the other hand, as will be described in detail later, since a defect structure that cannot be erased by any means is generated, there is a problem that a large stress distribution is induced inside the fiber when this agglomeration gives stress to the fiber. The fiber skin core structure and the like are considered to be one of the defect structures.

  The present inventors have found that keeping the crystal size derived from the monoclinic low is most important in increasing the nodule strength. The reason is not clear, but when the X-ray diffraction of the obtained polyethylene fiber was taken, a few monoclinic diffraction-derived peaks were confirmed, although the diffraction point derived from the orthorhombic crystal system was the main. As a result of this study, it was found that it is important to keep the crystal size derived from monoclinic diffraction below a certain level. The reason for this is not exactly clear, but I understand that it is roughly as follows. That is, it was found that when stretched from the state of a xerogel without a solvent, the size of the monoclinic-derived crystal grows relatively large, probably because there are few solvent molecules that inhibit the growth of the monoclinic crystal. When the monoclinic crystal grows to a size larger than a certain limit, stress concentration occurs between the monoclinic-derived crystal and the orthorhombic-derived crystal when the fiber is deformed, which may be the starting point of fracture. As a result, it is disadvantageous from the viewpoint of nodule strength, which is not preferable.

  Next, the present inventors have found that there is a correlation between the knot strength and the fine crystal size, orientation, and variation of these structural parameters at each fiber part. In order to improve the knot strength, the ideal state is that the fiber can be bent flexibly and arbitrarily regardless of whether it is viewed microscopically or macroscopically. At this time, it is necessary to suppress the possibility that the fiber fine structure is broken due to the bending as much as possible. At this time, it is necessary to increase the crystal orientation and crystal size of the fiber as much as possible. At the same time, if they are made too large, the contrast (contrast) with the remaining amorphous region is too high, so that the nodule strength tends to deteriorate. Furthermore, the present inventors have also found that it is important to make the crystal size and orientation at each part of the fiber approximately the same. If there is structural inhomogeneity such as crystal size or orientation between each part of the fine structure, especially between adjacent parts, stress concentration occurs starting from the non-uniform part when deformed, and as a result It was found that the nodule strength was reduced.

  The stress distribution generated in the structure can be measured using the Raman scattering method, as shown by Young et al. (Journal of Materials Science, 29, 510 (1994)). The Raman band, that is, the reference vibration position, is determined by solving an equation composed of the force constant of the molecular chain constituting the fiber and the shape of the molecule (internal coordinates) (E. B. Wilson, JC. Decius, PC Cross, Molecular Vibrations, Dover Publications (1980)). As a theoretical explanation of this phenomenon, according to Wool et al., For example, the molecule is distorted as the fiber is distorted, and as a result, the reference vibration position is changed (Macromolecules, 16, 1907 (1983)). .

  When structural non-uniformity such as defect aggregation exists, when external strain is applied, the stress generated varies depending on the site in the fiber. This change can be detected as a change in the band profile. Conversely, when stress is applied to the fiber, the stress distribution induced inside the fiber can be quantified by examining the relationship between the strength and the change in the Raman band profile. . That is, the fiber having a small structural non-uniformity takes a value in a region having a Raman shift factor, as will be described later.

  In addition to the above, the high-strength polyethylene fiber by the "gel spinning method" disclosed so far has a very strong tensile strength due to its highly oriented structure, but when the fiber is bent like the knot strength, There was a drawback that it was easily broken at a relatively low stress. Furthermore, if a non-uniform structure exists in the fiber in the cross-sectional direction of the fiber, such as a skin core structure, the fiber is more easily broken in a bent state. The present inventors have conducted intensive studies, and that fibers with small structural nonuniformity are strong in the bent state in a bent state, and fibers with small structural nonuniformity have a high ratio of knot strength to tensile strength. I found out.

  The disadvantages of the high-strength polyethylene fibers by the “gel spinning method” disclosed so far are that the strength between single yarn fibers depends on the state after spinning from the nozzle holes, compared to the fibers obtained by the ordinary melt spinning method. It was that non-uniformity would occur. For this reason, there has been a problem that there exists a single yarn having a remarkably low strength compared to the strength per average fineness of the yarn. If there is a single fiber having a strength lower than the average strength in the fiber, for example, when the fiber is subjected to friction, especially when this fiber is used for fishing line, rope, bulletproof, protective clothing, etc. If unevenness exists, stress concentrates in a thin part and breaks. Also, in the manufacturing process, it causes a process trouble due to a single yarn breakage, which adversely affects productivity.

  An object of the present invention is to provide a high-performance rope comprising these high-strength polyethylene fibers which are improved in these problems and have excellent uniformity with little variation in strength between single yarns.

  The present inventors diligently studied and found that the strength of the filaments constituting the fibers was high and the internal structure of the fibers was uniform, which was difficult to obtain by a technique such as the conventional gel spinning method. The present inventors have succeeded in obtaining a novel polyethylene fiber with little variation, and reached the present invention by using this for a rope.

  The present invention relates to the following ropes using specific high-strength polyethylene fibers. That is, the polyethylene fiber usually contains two kinds of crystals, orthorhombic (rectangular) and monoclinic (oblique), but the high-strength polyethylene fiber in the present invention has a small monoclinic-derived crystal size. There is a feature.

[1] A rope comprising high-strength polyethylene fibers having a monoclinic-derived crystal size of 9 nm or less.
[2] The rope according to [1], wherein in the high-strength polyethylene fiber, the ratio of the crystal size derived from the ortholone big crystal (200) and the (020) diffraction plane is 0.8 or more and 1.2 or less.
[3] The rope according to [1] or [2], wherein the high-strength polyethylene fiber has a stress Raman shift factor of −5.0 cm ⁻¹ / (cN / dTex) or more.
[4] The rope according to any one of [1] to [3], wherein the high-strength polyethylene fiber has an average strength of 20 cN / dTex or more.
[5] The rope according to any one of [1] to [4], wherein the monofilament constituting the high-strength polyethylene fiber has a knot strength retention of 40% or more.
[6] The rope according to any one of [1] to [5], wherein CV indicating variation in single yarn strength of monofilaments constituting the high-strength polyethylene fiber is 25% or less.
[7] The rope according to any one of [1] to [6], wherein the breaking elongation of the monofilament constituting the high-strength polyethylene fiber is 2.5% or more and 6.0% or less.
[8] The rope according to any one of [1] to [7], wherein the single filament fineness of the monofilament constituting the high-strength polyethylene fiber is 10 dTex or less.
[9] The rope according to any one of [1] to [8], wherein the high-strength polyethylene fiber has a melting point of 145 ° C or higher.

The high-strength polyethylene fiber in the present invention has an extremely small number of defects existing inside the fiber that has not been suppressed to a sufficiently low level by the conventional gel spinning method, and the strength of the filaments constituting the multifilament is small and uniform. Fiber.
According to the present invention, by using such high-strength polyethylene fiber, the breaking strength at the eye-processed portion is increased and the bending wear resistance is improved as compared with the rope using the conventional ultra-high molecular weight polyethylene fiber. High performance rope that can be used for a long time can be obtained.

Hereinafter, the present invention will be described in detail.
With respect to the method for obtaining the fiber according to the present invention, a new method is required. For example, the following methods are recommended, but are not limited thereto.
In the production of this fiber, it is preferable to use ultrahigh molecular weight polyethylene as the high molecular weight polyethylene used as the raw material. The intrinsic viscosity [η] of such polyethylene is preferably 5 or more, more preferably 8 or more, and still more preferably 10 or more. If the intrinsic viscosity is too low, a high strength fiber exceeding the desired strength of 20 cN / dtex may not be obtained. On the other hand, the intrinsic viscosity [η] of polyethylene is preferably 35 or less, more preferably 30 or less, and still more preferably 25 or less. If the intrinsic viscosity is too high, processability may be reduced and fiberization may be difficult.

  The ultra high molecular weight polyethylene in the present invention is characterized in that the repeating unit is substantially ethylene, and a small amount of other monomers such as α-olefin, acrylic acid and derivatives thereof, methacrylic acid and derivatives thereof, vinylsilane and It may be a copolymer with a derivative thereof, a copolymer with these copolymers, a copolymer with an ethylene homopolymer, or a blend with another homopolymer such as an α-olefin. Good. In particular, by using a copolymer with an α-olefin such as propylene and butene-1, the incorporation of a short chain or a long chain branch to a certain degree is necessary for the production of fibers, particularly in spinning and drawing, in terms of yarn production stability. It is more preferable because it can impart the properties. However, if the content other than ethylene is excessively increased, it becomes an obstructive factor for stretching. Therefore, from the viewpoint of obtaining a high-strength and high-modulus fiber, other monomers such as α-olefin are 0.2 mol% or less in monomer units. Preferably, the content is 0.1 mol% or less. Of course, a homopolymer of ethylene alone may be used.

  In the production method recommended by the present invention, it is preferable to dissolve such a high molecular weight polyethylene using a volatile organic solvent such as decalin or tetralin. If the solvent is solid or non-volatile at room temperature, the productivity in spinning tends to be very poor. When a volatile solvent is used, the solvent present on the surface of the gel yarn after being discharged from the spinneret slightly evaporates at the initial stage of spinning, but the spinning state is stabilized by the cooling effect due to the latent heat of evaporation accompanying the evaporation of the solvent at this time. Presumed to be. The concentration at the time of dissolution is preferably 30 wt% or less, more preferably 20 wt% or less. The optimum concentration is selected according to the intrinsic viscosity [η] of the raw ultrahigh molecular weight polyethylene. Further, in the spinning stage, the spinneret temperature is preferably 30 ° C. or higher than the melting point of polyethylene and lower than the boiling point of the solvent used. In the temperature range near the melting point of polyethylene, the viscosity of the polymer is too high, making it difficult to take up at a rapid speed. Further, a temperature higher than the boiling point of the solvent to be used is not preferable because the solvent boils immediately after leaving the spinneret, and yarn breakage may frequently occur directly under the spinneret.

The important factors in the method of producing uniform fibers recommended by the present invention will be described.
The first is to supply a pre-rectified high-temperature inert gas independently to each discharge solution discharged from the orifice under the nozzle. The speed of the inert gas supplied at this time is preferably within 1 m / s. When the speed is too high, the evaporation rate of the solvent becomes high, and a non-uniform structure may be formed in the yarn cross-sectional direction. Furthermore, the fiber may break. Further, the temperature of the inert gas at this time is preferably in the range of plus or minus 10 ° C., more preferably in the range of plus or minus 5 ° C. with respect to the nozzle temperature. By supplying an inert gas independently to each discharge yarn shape, the cooling state of each yarn shape becomes uniform, and an undrawn yarn having a uniform structure is obtained. By uniformly stretching the unstretched yarn having this uniform structure, it is possible to obtain a desired uniform high-strength polyethylene fiber.

The second factor is to rapidly and uniformly cool the discharged gel yarn discharged from the spinneret and to control the cooling rate difference between the cooling medium and the gel yarn. The cooling rate is preferably 1000 ° C./s or more, more preferably 3000 ° C./s or more. Regarding the speed difference, it is preferable that the integrated value of the speed difference (integrated with the time after discharge from the die), that is, the cumulative speed difference is 30 m / min or less. More preferably, it is 15 m / min or less. By the above, the undrawn yarn excellent in uniformity can be obtained. Where the cumulative speed difference is:
Cumulative speed difference = ∫ (thread speed-speed of cooling medium in the thread take-up direction)
Can be calculated based on

Thus, by rapidly and uniformly cooling, an undrawn yarn having a uniform fiber cross-sectional direction can be produced. When the cooling rate of the discharged yarn is slowed, a non-uniform state tends to occur in the internal structure of the fiber. In the case of multifilaments, non-uniformity among filaments increases when the cooling state of each filament is different. Further, if the speed difference between the take-off yarn shape and the cooling medium is large, it becomes difficult to take up at a sufficient spinning speed due to the frictional force between the take-up yarn shape and the cooling medium.
In order to obtain such a cooling rate, it is recommended to use a liquid having a large heat transfer coefficient as a cooling medium. Among these, a liquid that is incompatible with the solvent to be used is preferable. For example, water is recommended for simplicity.

  Third, the gas medium space that travels until the discharged gel yarn discharged from the spinneret comes into contact with the cooling medium is covered with a member. When the gas medium space is not shielded from the external space, the discharge gel filament cooling rate and the solvent evaporation rate from the discharge gel filament fluctuate for each monofilament in the gas medium space due to fluctuations in the temperature and wind speed of the external space. However, the structure between the monofilaments becomes non-uniform. Furthermore, the monofilament may break. It is recommended that the member has a heat insulating structure. For example, heat-resistant glass is recommended so that the state of the discharged gel yarn can be visually recognized. When it is not necessary to visually recognize the state of the discharged gel yarn, a metal member having a double structure through a substantially vacuum portion may be used.

  When a liquid is used as the cooling medium, it is important that the liquid level fluctuation is 1 mm or less. When the liquid level fluctuation exceeds 1 mm, the fluctuation of the transit time of the gas medium space between the longitudinal direction of the monofilament and between the monofilaments becomes remarkable, and the structure nonuniformity of the monofilament may become remarkable in the longitudinal direction and between the filaments. . In particular, when the liquid level fluctuation is severe, the monofilament breaks in the gas medium space.

  When a liquid that is incompatible with the solvent and has a higher specific gravity than the solvent is used as the cooling medium, the solvent volatilized from the discharged gel filaments liquefies while passing through the gas medium, and the upper layer of the cooling medium over time To accumulate. It is necessary to continuously remove the accumulated solvent from the portion where the gel filament enters the cooling medium. When the accumulated solvent is not removed, the thickness of the solvent layer accumulated at the gel thread entry increases with time, and the gel threads are fused. When the gel yarns are severely fused, the yarn physical properties are remarkably lowered.

  In order to reduce the accumulated speed difference, the following method can be considered, but the present invention is not limited thereto. For example, a method in which a funnel is attached to the center of a cylindrical bath and the liquid and the gel yarn are drawn simultaneously, or the gel yarn is taken along the falling liquid like a waterfall at the same time is recommended. By using such a method, it is possible to reduce the accumulated speed difference as compared with the case where the gel yarn is cooled using a stationary liquid.

The obtained unstretched yarn is further heated and stretched several times, sometimes in multiple stages while removing the solvent, whereby a high-strength polyethylene fiber excellent in the uniformity of the internal structure can be produced. At this time, the deformation speed of the fiber at the time of drawing is mentioned as an important parameter. If the deformation rate of the fiber is too high, the fiber breaks before reaching a sufficient draw ratio, which is not preferable. On the other hand, if the deformation rate of the fiber is too slow, the molecular chain is relaxed during stretching, and the fiber becomes thin by stretching, but a fiber having high physical properties cannot be obtained. Thus, a preferred deformation rate is 0.005 s ^-1 or 0.5 s ^-1 or less. More preferably, at 0.01s ^-1 or 0.1s ^-1 or less. The deformation speed can be calculated from the draw ratio of the fiber, the draw speed, and the length of the heating section of the oven. In other words, the deformation speed is
Deformation rate (s ⁻¹ ) = (1-1 / stretch ratio) It is expressed as stretch rate / length of heating section.
In order to obtain a fiber having a desired strength, it is recommended that the draw ratio of the fiber is 10 times or more, preferably 12 times or more, and more preferably 15 times or more.

  In the high-strength polyethylene fiber according to the present invention, the crystal size derived from the monoclinic is desirably 9 nm or less, more desirably 8 nm or less, and particularly desirably 7 nm or less. If the crystal size is too large, when the fiber is deformed, stress concentration occurs between the monoclinic-derived microcrystals and the orthorhombic-derived microcrystals, which may be the starting point of fracture.

  In the high-strength polyethylene fiber according to the present invention, the ratio of the crystal size derived from the orthorhombic crystal (200) and the (020) diffraction plane is preferably 0.8 or more and 1.2 or less. Here, the ratio of the crystal size derived from the orthorhombic crystal (200) and the (020) diffraction plane is the crystal size corresponding to the length perpendicular to the (200) plane and the length perpendicular to the (020) plane. The ratio of crystal sizes corresponding to. More preferably, it is 0.85 or more and 1.15 or less, and particularly preferably 0.9 or more and 1.1 or less. When the crystal size ratio is too small, or when the crystal size ratio is too large, when considering the shape of the crystal, it becomes a form selectively grown in one axial direction. For this reason, when the fibers are deformed, collisions may occur between the microcrystals existing around them, which may cause stress concentration and structural destruction.

In the high-strength polyethylene fiber according to the present invention, the stress Raman shift factor is preferably −5.0 cm ⁻¹ / (cN / dTex) or more, more preferably −4.5 cm ⁻¹ / (cN / dTex) or more. It is particularly preferably −4.0 cm ⁻¹ / (cN / dTex) or more. When the stress Raman shift factor is small, the existence of a stress distribution due to stress concentration is suggested.

  In the high-strength polyethylene fiber according to the present invention, the average strength is desirably 20 cN / dTex or more, more desirably 22 cN / dTex or more, and particularly desirably 24 cN / dTex or more. If the average strength is too small, the strength of the product may be insufficient when an applied product is created.

  The knot strength retention of the monofilament constituting the high-strength polyethylene fiber in the present invention is preferably 40% or more, more preferably 43% or more, and particularly preferably 45% or more. If the retention rate of knot strength is too small, the yarn may be damaged during the process when creating a rope as an applied product.

  The CV showing the variation in the single yarn strength of the monofilament constituting the high-strength polyethylene fiber in the present invention is preferably 25% or less, more preferably 23% or less, and particularly preferably 21% or less. When CV which shows the dispersion | variation in single yarn intensity | strength is too large, when the rope as an applied product is created, the dispersion | variation in the intensity | strength as a product may arise.

  The breaking elongation of the monofilament constituting the high-strength polyethylene fiber in the present invention is preferably 2.5% or more and 6.0% or less, more preferably 3.0% or more and 5.5% or less. Desirably, it is 3.5% or more and 5.0% or less. When the elongation at break is too small, the operability may be deteriorated due to breakage of the single yarn of the fiber during the manufacturing process. If the elongation at break is too large, the effect of permanent deformation may not be negligible when used as a product.

  The monofilament fineness of the monofilament constituting the high-strength polyethylene fiber in the present invention is desirably 10 dTex or less, more desirably 8 dTex or less, and particularly desirably 6 dTex or less. If the single yarn fineness is too large, it may be difficult to improve the product performance to the desired mechanical properties in the fiber production process. The fineness of the single yarn is preferably small, but if it is too thin, fluff tends to stand, so 0.1 dTex or more is desirable.

  The melting point of the high-strength polyethylene fiber in the present invention is preferably 145 ° C. or higher, more preferably 148 ° C. or higher. When the melting point of the fiber is 145 ° C. or higher, the fiber can withstand higher temperatures in a process that requires heating, which is desirable from the viewpoint of labor saving in processing.

The high-performance rope of the present invention comprises the above-described high-strength polyethylene fiber, and there is little variation in the strength of the monofilament itself, and locally weak parts can be reduced. Therefore, the occurrence of a portion that breaks quickly can be reduced as a whole rope, and as a result, a rope having high strength and high reliability can be obtained.
Moreover, as long as the rope of this invention contains said high-strength polyethylene fiber, the other fiber may be mixed. Therefore, the outer periphery may be coated with another material such as low molecular weight polyolefin or urethane resin depending on the design and function. As for the form of the rope, the twisted structure such as three-strike or six-strike, the knitted structure such as eight-strike, twelve-strike, double-strike struts, etc. By finishing the double-blade structure, an ideal rope can be designed according to the application and performance.

  Hereinafter, the effectiveness of the present invention will be described with reference to examples and the like, but the present invention is not limited thereto. In addition, the evaluation method of the physical property in the following examples etc. is as follows.

(Strength / elongation / elastic modulus of multifilament)
A strain-stress curve was measured under the conditions of an ambient temperature of 20 ° C. and a relative humidity of 65% under the conditions of a sample length of 200 mm (length between chucks) and an elongation rate of 100% / min. . The strength (cN / dTex) and elongation (%) were determined from the stress and elongation at the breaking point, and the elastic modulus (cN / dTex) was calculated from the tangent that gives the maximum gradient near the origin of the curve. In addition, each value used the average value of 10 times of measured values.

(Single fiber strength, etc.)
When measuring the strength and elastic modulus of the filament (single fiber), ten single yarns (filaments) were randomly extracted from one multifilament to be measured to prepare a sample. When the number of filaments was less than 10, all single yarns (filaments) were measured.
About 2 m of single fibers were each taken out, the weight was measured using 1 m of the fibers, and the fineness (dTex) was converted into 10,000 m. When measuring the length of this single yarn fiber 1 m, a constant length sample was prepared by applying a load of about 1/10 of the single yarn fineness. The remaining part was used to measure the strength in the same way as the strength of the fiber. CV is the following formula:
CV = standard deviation of single yarn strength / average value of single yarn strength × 100
Calculated by

(Nodule strength retention rate of single fiber)
When measuring the knot strength retention of a filament (single fiber), ten single yarns (filaments) were randomly extracted from one multifilament to be measured, and used as a sample. When the number of filaments was less than 10, all single yarns (filaments) were measured.
About 2 m of single fibers were each taken out, the weight was measured using 1 m of the fibers, and the fineness (dTex) was converted into 10,000 m. When measuring the length of this single yarn fiber 1 m, a constant length sample was prepared by applying a load of about 1/10 of the single yarn fineness. Furthermore, after making a knot in the middle of a single fiber using the remaining part of the fiber, a tensile test was performed in the same manner as described in “Strength / Elongation / Elasticity of Multifilament”. At this time, how to make a knot was performed according to FIG. 3 described in JIS L1013. Note that the direction of the knot is always the same as b in FIG. The nodule strength retention is given by the following formula:
Knot strength retention = average value of single yarn knot strength / average value of single yarn strength × 100
Sought by.

(Intrinsic viscosity)
Using a Ubbelohde capillary viscometer, measure the specific viscosity of various dilute solutions in decalin at 135 ° C, plot the viscosity against the concentration, and extrapolate the origin of the straight line obtained by least square approximation to the origin From this, the intrinsic viscosity was determined.
For measurement, the sample was divided or cut into lengths of about 5 mm, 1 wt% antioxidant (trade name “Yoshinox BHT” manufactured by Yoshitomi Pharmaceutical) was added to the polymer, and the mixture was stirred and dissolved at 135 ° C. for 4 hours. Thus, a measurement solution was prepared.

(Melting point)
The measurement was performed using “DSC7 type” manufactured by Perkin Elmer as a differential scanning calorimeter. About 5 mg of a sample cut in advance to 5 mm or less is filled and sealed in an aluminum pan. The same empty aluminum pan is used as a reference, and the temperature is increased from room temperature to 200 ° C. at a rate of 10 ° C./min. It was. The temperature at the peak top of the melting peak appearing on the lowest temperature side of the obtained curve was taken as the melting point.

(Raman scattering measurement)
The Raman scattering spectrum was measured according to the following method. A Renishaw system 1000 was used as a Raman measuring device (spectrometer). A helium-neon laser (wavelength: 633 nm) was used as a light source, and the measurement was performed by setting the fiber so that the fiber axis was parallel to the polarization direction.
Single fiber (monofilament) is split from yarn and pasted on the center line of a hole in a cardboard with a rectangular hole (50 mm in length and 10 mm in width) so that the long axis coincides with the fiber axis, and both ends are bonded with epoxy Stopped with an agent (Araldite) and left for more than 2 days. Thereafter, the fiber is attached to a jig whose length can be adjusted with a micrometer, and after carefully cutting off the cardboard holding the single fiber, a predetermined load is applied to the fiber, and it is placed on the microscope stage of the Raman scattering device, Raman spectrum was measured. At this time, the stress and strain acting on the fiber were measured simultaneously. Measurement of Raman, at Static Mode, the 1350 cm ^-1 from the measurement range 850 cm ^-1, were collected data resolution per pixel as 1 cm ^-1 or less. As a peak used for the analysis, a band of 1128 cm ⁻¹ belonging to a symmetric stretching mode of CC skeleton bond was adopted.
In order to accurately determine the band centroid position and line width (standard deviation of the profile centered on the band centroid, square root of the second moment), the curve can be fit well by approximating the profile as a composite of two Gaussian functions. I understood. It was found that when the distortion was applied, the peak positions of the two Gaussian functions did not match and the distance between them increased. In such a case, in the present invention, the band position is not considered as the apex of the peak profile, but is defined as the band peak position by the centroid position of the two Gaussian peaks. The definition is as follows (center of gravity, <x>):

<X> = ∫x f (x) dx / ∫f (x) dx
f (x) = f1 (x-a) + f2 (x-b)
(Where fi represents a Gaussian function)
Shown in A graph plotting the band centroid position <x> and the stress applied to the fiber was created, and the gradient of the approximate curve passing through the origin using the least square method of the obtained plot was defined as the stress Raman shift factor.

(Evaluation of crystal size and orientation)
Evaluation of crystal size and orientation was performed using an X-ray diffraction method. As an X-ray source, a large synchrotron radiation facility SPring8 was used as an X-ray source, and a BL24XU hatch was used. The energy of the X-ray used was 10 keV (λ = 1.398Å). The X-rays taken out through the undulator were monochromatic through a monochromator (silicon crystal (111) plane) and then set to converge at the sample position using a phase zone plate. The size of the focal point was adjusted so that the diameter was 3 μm or less in both vertical and horizontal directions. The sample fiber is placed on the XYZ stage so that the fiber axis is horizontal. The stage was finely moved while detecting using a separately installed Thomson scattering detector, the Thomson scattering intensity was measured, and the point where the intensity reached the maximum was determined as the center of the fiber. Since the X-ray intensity is very high, the sample is damaged if the exposure time of the sample is too long. Therefore, the exposure time during X-ray diffraction measurement was set to be within 2 minutes. Under these measurement conditions, a beam was applied to five or more sites at substantially equal intervals from the skin portion to the center portion of the fiber, and the X-ray diffraction pattern at each location was measured. X-ray diffraction patterns were recorded using Fuji imaging plates. Data reading was performed using Fuji microluminography. The recorded image data was transferred to a personal computer, and data in the equator direction and azimuth direction were cut out, and then the line width was evaluated. The crystal size (ACS) can be calculated from the half width β of the diffraction profile in the equator direction by the following formula (III):

ACS = 0.9λ / βcosθ (III)
(Where λ is the wavelength of the X-ray used, 2θ is the diffraction angle)
It calculated using Scherrer's formula shown below. The diffraction peak was identified according to Bunn et al. (Trans Faraday Soc., 35, 482 (1939)). As the crystal size, an average value obtained by measuring and evaluating 5 points or more was adopted. CV is the following formula:

CV = standard deviation of crystal size / average value of crystal size × 100
It calculated using.

As the orientation angle OA, the half width of the profile obtained by scanning in the azimuth direction for each of the obtained two-dimensional diffraction patterns was employed. An average value obtained by measuring and evaluating five or more points was adopted as the orientation angle. CV is:
CV = standard deviation of orientation angle / average value of orientation angle × 100
It calculated using.

(Evaluation method of monoclinic crystal size)
The crystal size was measured using an X-ray diffraction method. The apparatus used for the measurement is Rigaku Lint 2500. A copper counter cathode was selected as the X-ray source. The operation output was 40 kV 200 mA. The collimator was 0.5 mm, the fiber was attached to a fiber sample stage, the counter was scanned in the equator direction and the meridian direction, and the X-ray diffraction intensity distribution was measured. At this time, the light receiving slit was selected to be 1/2 ° for both the vertical limit and the horizontal limit. The crystal size (ACS) is calculated from the half width β of the diffraction profile by the following formula (IV):

ACS = 0.9λ / β0cosθ (IV)
However, β0 = (β2 −βs) 0.5
(Where λ is the wavelength of the X-ray used, 2θ is the diffraction angle, and βs is the half-value width of the X-ray beam itself measured using a standard sample.)
It calculated using Scherrer's formula shown below.

The monoclinic crystal size was determined by calculating ACS using the Scherrer equation from the line width of the diffraction point derived from monoclinic (010). The diffraction peaks were identified according to Seto et al. (Jap. J. Appl. Phys., 7, 31 (1968)).
The ratio of the ortholonevic crystal size was obtained by dividing the crystal size derived from the (200) diffraction plane by the crystal size derived from the (020) diffraction plane.

(Strength and durability)
A rope with eye processing on both ends was prepared, and for the purpose of preventing slipping, a urethane-based resin was impregnated and dried. The strength of the rope was measured at a tensile speed of 20 cm / min using a hydraulic servo type strength tester (servo pulser) manufactured by Shimadzu Corporation after fixing both ends of the rope with pins.
Further, the bending wear test was performed by passing the rope to a pulley of 250 mmφ and bending it repeatedly 1 million times with a load of 40% of the breaking strength applied. The rope after the test was subjected to eye processing on both ends in the same manner as described above, the rope strength was measured, and the residual rate (%) before and after the bending wear test was calculated.

(Examples 1-3)
Ultra high molecular weight polyethylene having an intrinsic viscosity of 21.0 dl / g and decahydronaphthalene were mixed at a weight ratio of 8:92 to form a slurry liquid. The material was melted by a twin screw extruder equipped with a mixing and conveying section, and the obtained transparent uniform material was circularly arranged at 30 holes and an orifice of 0.8 mm in diameter at 1.8 g / min. Extruded. By passing the extruded dissolved material through a 10 mm long air gap through a cylindrical flow tube (covered with 5 mm thick heat-resistant glass and shielded from the external space) filled with water in a steady flow, The fluctuation is suppressed to 0.5 mm or less, and the decahydronaphthalene accumulated on the liquid surface is uniformly cooled while continuously removing from the portion where the extruded dissolved material enters the water surface, and the solvent in the extruded dissolved material is removed. The gel yarn was drawn at a spinning speed of 60 m / min without being removed from the extruded dissolved material. At this time, the cooling rate of the fiber was 9667 ° C./s, and the cumulative speed difference was 5 m / min. Next, the gel fiber was stretched at a stretch ratio of 3 times in a nitrogen heating oven without winding the gel fiber, and the stretched yarn was wound up. Subsequently, the fiber was drawn at a draw ratio of up to 6.5 times at 149 ° C. to obtain drawn yarns having various draw ratios.
Various physical properties of the obtained polyethylene fiber are shown in Table 1.

(Examples 4 and 5)
The ultra-high molecular weight polyethylene polymer having an intrinsic viscosity of 19.6 was dissolved in a screw-type kneader set at a temperature of 230 ° C. while dispersing a slurry-like mixture of 10 wt% and decahydronaphthalene 90 wt%. A single-hole discharge rate of 1.2 g / min was supplied to a die having a set diameter of 0.6 mm and 400 holes by a lightweight pump. In the collar-type quenching equipment installed directly under each nozzle, pay attention to the rectification of 0.1 m / s of nitrogen gas, and evenly strike each thread to be discharged as much as possible. A polyethylene fiber was produced in the same manner as in Example 1 except that a very small amount of decalin was evaporated and an air gap in a nitrogen atmosphere was passed. In addition, the draw ratio of the second stage was 4.5 and 6.0 times. At this time, the nitrogen temperature used for quenching was controlled at 178 ° C. Moreover, temperature control was not performed regarding the air gap.
Table 1 shows the physical property values of the obtained fibers. It was found to be very uniform and have high strength.

(Comparative Example 1)
Dissolve an ultrahigh molecular weight polyethylene having an intrinsic viscosity of 19.6 with a screw type kneader set at a temperature of 230 ° C. while dispersing a slurry mixture of 10 wt% and decahydronaphthalene 90 wt%, and set the temperature to 175 ° C. A single-hole discharge rate of 1.6 g / min was supplied to a die having 400 holes with a diameter of 0.6 mm by a lightweight pump. Care is taken to rectify nitrogen gas adjusted to 100 ° C. at a high speed of 1.2 m / s at a slit-like gas supply orifice installed directly under the nozzle, and decalin on the surface of the fiber so that it strikes the yarn as evenly as possible. The decalin remaining in the fibers was evaporated with a nitrogen flow set at 115 ° C., and was taken up at a speed of 80 m / min with a Nelson-shaped roller installed downstream of the nozzle. At this time, the length of the quench section was 1.0 m, the fiber cooling rate was 100 ° C./s, and the cumulative speed difference was 80 m / min. Subsequently, the obtained fiber was stretched 4.0 times in a heating oven at 125 ° C., and then the fiber was stretched 4.1 times in a heating oven set at 149 ° C. Uniform fibers could be obtained without breaking during the process. Table 1 shows the physical property values of the obtained fibers.

(Comparative Example 2)
A drawn yarn was obtained in the same manner as in the Examples except that a gel yarn was obtained by applying a nitrogen air of 50 ° C. and 0.5 m / s as evenly as possible while being careful of rectification from a position 10 mm directly from the orifice. Got. The fiber cooling rate at this time was 208 ° C./s, and the cumulative speed difference was 80 m / min.

(Comparative Example 3)
Dissolve in a screw-type kneader set at a temperature of 230 ° C. while dispersing a slurry-like mixture of 15 wt% of ultrahigh molecular weight polymer (C) having an intrinsic viscosity of 10.6 and 85 wt% of paraffin wax. Then, a single-hole discharge rate of 2.0 g / min was supplied to a die having a diameter of 1.0 mm set to 190 ° C. and 400 holes by a lightweight pump. It was immersed in a spinning bath filled with n-hexane at 15 ° C. with an air gap of 30 mm. The infiltrated fiber was taken up at a speed of 50 m / min with a Nelson-shaped roller. The fiber cooling rate at this time was 4861 ° C./s, and the cumulative speed difference was 50 m / min. Subsequently, the obtained fiber was stretched 3.0 times in a heating oven at 125 ° C. The fiber was further stretched 3 times in a heating oven set at 149 ° C. and then stretched 1.5 times again. did. Uniform fibers could be obtained without breaking during the process. Table 1 shows the physical property values of the obtained fibers.

(Comparative Example 4)
The undrawn fiber prepared and wound under the same conditions as in Comparative Example 1 was immersed in ethanol for 3 days to remove decalin remaining in the yarn, and then air-dried for 2 days to produce a xerogel fiber. Further, the xerogel fiber was stretched 4.0 times in a heating oven at 125 ° C. Subsequently, this fiber was stretched 4.3 times in a heating oven set at 155 ° C. Uniform fibers could be obtained without breaking on the way.

(Example 6)
The fibers obtained in accordance with the description in Example 1 were combined so as to have a density of about 1 million denier, and 36 t / m was twisted on the S twist to produce a twisted yarn. Further, 10 twisted yarns were combined and 12 t / twisted on the Z twist. The yarn was obtained by twisting m. Seven yarns were bundled to obtain a strand. The strands were combined on 8 blades to prepare an 8-pipe blade rope having a diameter of about 10 mm. Table 2 shows the results of the tensile test, the breakage at that time, and the strength and residual rate after the bending wear test.

(Example 7)
The fibers obtained according to the description in Example 4 are combined to a density of about 1 million denier, and 36 t / m twist is applied to the S twist to produce a twisted yarn. The yarn was obtained by twisting m. Seven yarns were bundled to obtain a strand. The strands were combined on 8 blades to prepare an 8-pipe blade rope having a diameter of about 10 mm. Table 2 shows the results of the tensile test, the breakage at that time, and the strength and residual rate after the bending wear test.

(Comparative Example 5)
The fibers obtained in accordance with the description in Comparative Example 1 are combined to make about 1 million denier, and a twisted yarn is produced by applying 36 t / m twist to the S twist, and 10 twisted yarns are further combined to a twist of 12 t / m for the Z twist. The yarn was obtained by twisting m. Seven yarns were bundled to obtain a strand. The strands were combined on 8 blades to prepare an 8-pipe blade rope having a diameter of about 10 mm. Table 2 shows the results of the tensile test, the breakage at that time, and the strength and residual rate after the bending wear test.

Table 2 summarizes the physical properties relating to rope applications obtained in Example 6, Example 7, and Comparative Example 5.

  The high-strength polyethylene fiber according to the present invention has a high strength and a high elastic modulus and a uniform internal structure of the fiber. A product using the high-strength polyethylene fiber does not have a performance-decreasing portion and has a uniformly high performance. Therefore, the strength of the eye processed portion at the end of the rope is improved, and the breaking strength of the rope is improved. Further, since durability is improved even in bending wear, a high-performance and high-quality rope can be obtained.

Claims (9)

  A rope comprising high-strength polyethylene fibers having a monoclinic-derived crystal size of 9 nm or less.   2. The rope according to claim 1, wherein in the high-strength polyethylene fiber, a ratio of crystal sizes derived from the orthorhombic crystal (200) and the (020) diffraction plane is 0.8 or more and 1.2 or less. The rope according to claim 1 or 2, wherein the high-strength polyethylene fiber has a stress Raman shift factor of -5.0 cm ^-1 / (cN / dTex) or more.   The rope according to any one of claims 1 to 3, wherein the high-strength polyethylene fiber has an average strength of 20 cN / dTex or more.   The rope according to any one of claims 1 to 4, wherein the knot strength retention of the monofilament constituting the high-strength polyethylene fiber is 40% or more.   The rope according to any one of claims 1 to 5, wherein CV indicating variation in single yarn strength of monofilaments constituting the high-strength polyethylene fiber is 25% or less.   The rope according to any one of claims 1 to 6, wherein the elongation at break of the monofilament constituting the high-strength polyethylene fiber is 2.5% or more and 6.0% or less.   The rope according to any one of claims 1 to 7, wherein the single filament fineness of the monofilament constituting the high-strength polyethylene fiber is 10 dTex or less.   The rope according to any one of claims 1 to 8, wherein the high-strength polyethylene fiber has a melting point of 145 ° C or higher.