JP6772504B2 - Braid made of high-performance polyethylene multifilament - Google Patents

Description

The present invention relates to a braid having excellent molding processability and high dimensional stability near room temperature when the product is used. Furthermore, various interior cord nets such as blind cords, pleated cords, pleated net door cords, curtain cords, light-shielding screens, concrete reinforcements, fishing threads, protective materials, bulletproof materials, surgical sutures, meat tightening threads, etc. Regarding safety gloves, safety ropes, fishing ropes, finishing ropes, mooring ropes, tow ropes, bow strings, and base materials for collecting organic and inorganic substances.

Braids made of multifilaments or monofilaments are used in many applications such as fishing threads, blind cords, and ropes. As the uses of these braids have diversified, the functionality of the braids that meets the required characteristics of the product is required. For example, when used for fishing threads, conventionally known fishing threads include threads made of synthetic fibers made of polyamide, polyester, polyolefin, etc., and threads made of metal fibers made of stainless steel, tungsten metal, amorphous metal, etc. It has been known. The fishing thread is required to have various characteristics depending on the type of fish to be caught and the method of fishing, but in general, it is desirable that the fishing thread is thin and has high strength. Therefore, by using a braid made of ultra-high molecular weight polyethylene fibers produced by a so-called gel spinning method, a fishing yarn having high strength and high elastic modulus is used (see, for example, Patent Publications 1 and 2). However, the fishing thread made of ultra-high molecular weight polyethylene fiber according to these inventions is excellent in terms of high strength and high elastic modulus, but since polyethylene fiber having high elastic modulus is used as a raw material, it is used during molding into a braid. It is difficult to align the fibers of. That is, if the tension in the molding process is too low, the entire threads are not aligned and slack is generated, making it difficult to obtain the desired strength and elastic modulus. Further, if the product is molded with an excessively high tension, single yarn breakage occurs, which makes it difficult to obtain the desired strength and elastic modulus, and also causes a problem that the process passability deteriorates due to the generation of fluff. Braids with looseness or broken single yarn are often discarded without being used as products, and the large environmental load is also a problem.

In order to reduce the above problems, a technique is used to heat and align the fibers during the molding process to braid, but since the raw material is polyethylene, the fiber strength decreases when the heating temperature is high, and as a result, the result is obtained. It was also a problem that the strength of the braid to be sewn was low. Therefore, the current situation is that there is a need for a technology that has excellent dimensional stability near room temperature used as a product, but that has excellent workability during molding of braids at a relatively low temperature that suppresses deterioration of the physical properties of polyethylene fibers. Is.

Tokukousho 60-47922 Japanese Patent Application Laid-Open No. 3-244334

An object of the present invention is to solve the above-mentioned conventional problems. A trace amount of low melting point olefin is contained in the fiber, and the fiber is produced through a spinning and drawing step, and not only the molding step at this time is appropriately controlled, but also the cooling step after the drawing step and the winding after the cooling step. By precisely controlling not only the tension at the time of picking but also the temperature and tension in the string making process using the fiber, the polyethylene fiber has excellent dimensional stability near room temperature used as a product. It is a braid made of polyethylene fiber having excellent workability at the time of molding a braid at a relatively low temperature, which suppresses deterioration of physical properties, and is intended to provide a highly functional braid that can be used as a fishing thread, a net, a rope, and a protective cover.

The present inventors have determined the amount of low melting point olefin contained in the fiber, the deformation conditions during spinning and drawing in the solid state, the cooling conditions after the drawing process, and the winding conditions, and the temperature in the string making process for braiding. As a result of diligent research on not only the conditions and tension conditions but also the composition of the obtained braid, shrinkage rate, thermal stress, and stability of mechanical properties, the present invention has been completed.

That is, the polyethylene fiber of the present invention is
1. 1. When the ultimate viscosity [η] is 5.0 dL / g or more and 25 dL / g or less, the repeating unit is made of ethylene of 90% or more, and the measurement is performed under a load of 70 ° C. and 5 cN / dtex after unraveling from the braid. It is characterized in that it is composed of one or more polyethylene fibers having an elongation amount of 5.0% or more after 2 hours and a heat shrinkage rate of 0.40% or less after 240 hours at 40 ° C. braid.
2. The braid made of the high-performance polyethylene fiber according to 1 above, wherein the fiber contains 1 ppm or more and 1% or less of a low melting point polyolefin having a melting point of 70 ° C. or more and 100 ° C. or less.
3.1 The braid according to any one of 1 and 2 above, wherein the stress at the time of stretching is 0.5 cN / dtex or more and 20 cN / dtex or less.
4. The braid according to any one of 1 to 3 above, wherein the braid is composed of three or more fibers, and one or more of the constituent fibers are polyethylene fibers.
5. The braid according to any one of 1 to 4 above, wherein the single yarn fineness is 3 dtex or more.
6. The braid made of the high-performance polyethylene fiber according to any one of 1 to 5 above, wherein the strength of the fiber unwound from the braid is 15 cN / dtex or more.
7. A fishing thread containing the high-performance polyethylene fiber according to any one of 1 to 6 above.
8. A rope containing the high-performance polyethylene fiber according to any one of 1 to 6 above.
9. A state in which polyethylene having an ultimate viscosity [η] of 5.0 dL / g or more and 30 dL / g or less and whose repeating unit is 90% or more of ethylene is spun and contains 10 ppm or more of a paraffin-based compound having a molecular weight of 100 or more after the spinning process. Then, after further drawing at a temperature of 80 ° C. or higher, the drawn yarn was cooled at a cooling rate of 3 ° C./sec or higher, and the obtained drawn yarn was wound with a tension of 0.001 to 7 cN / dtex. The fibers are twisted as desired, and in the next string-making process, the polyethylene fibers constituting the braid are heated to temperatures of 70 ° C. or higher and 160 ° C. or lower for 30 minutes or less, and the polyethylene fibers are heated during heating. A method for producing a braid, wherein the tension is 0.005 cN / dtex or more and 15 cN / dtex or less.
10. The method for producing a braid according to 9 above, wherein the braid is stretched 1.05 times or more and 15 times or less at 160 ° C. or less after the string is made.

The braid of the present invention is characterized in that it has excellent dimensional stability near room temperature used as a product, and at the same time, it has excellent workability during molding of the braid at a relatively low temperature, which suppresses deterioration of the physical properties of polyethylene fibers. is there. In addition, fishing threads using this braid, various interior cord nets such as blind cords, pleated cords, pleated net door cords, curtain cords, light-shielding screens, etc. that require raising and lowering and opening and closing, protective materials, surgical sutures, meat tightening threads. , Safety gloves, safety ropes, fishing ropes, finishing ropes, western bow strings, etc. Further, the braid of the present invention is not limited to the above-mentioned molded processed products, but exhibits excellent performance as a base material for collecting organic substances and inorganic substances and a base material for water retention by combining with various materials, and can be widely applied. It is a thing.

Hereinafter, the present invention will be described in detail. The tensile strength of the polyethylene fiber used for the braid is preferably 13 cN / dtex or more. More preferably, it is 20 cN / dtex or more, and even more preferably 25 cN / dtex or more. The upper limit of the tensile strength is not particularly limited, but it is technically and industrially difficult to obtain a polyethylene fiber having a tensile strength exceeding 60 cN / dtex. The initial elastic modulus is preferably 250 cN / dtex or more and 1500 cN / dtex or less. More preferably, it is 350 cN / dtex or more, further preferably 550 cN / dtex or more, more preferably 1200 cN / dtex or less, still more preferably 1000 cN / dtex or less. If the initial elastic modulus exceeds 15001500 cN / dtex, it becomes difficult to align the braids during the molding process, and single yarn breakage occurs frequently, which is not preferable. The method for measuring the tensile strength and the initial elastic modulus will be described in detail in Examples.

The single yarn fineness of the polyethylene fibers constituting the braid in the present invention is preferably 3 dtex or more. More preferably, it is 4 dtex or more, and further preferably 5 dtex or more. When the single yarn fineness is less than 3 dtex, the single yarn breakage occurs frequently in the braid molding process, which is an important problem of the present invention, and the workability is deteriorated, which is not preferable.

The high-strength polyethylene fiber constituting the braid of the present invention preferably has an ultimate viscosity of 5.0 to 25 dL / g, more preferably 7.0 to 22 dL / g, and more preferably 8 to 20 dL / g. When the ultimate viscosity is 4.9 dL / g or less, the dimensional stability is excellent, the fluctuation of mechanical properties with time is small, and the strength of 10 cN / dtex or more cannot be obtained. On the other hand, when the ultimate viscosity exceeds 25 dL / g, polyethylene fibers having high strength and high elastic modulus can be produced, but this is not preferable because single yarn breakage occurs frequently during braid molding. By setting the ultimate viscosity to 5.0 dL / g or more, the number of structural defects in the product can be reduced by reducing the molecular terminal groups of polyethylene. Therefore, it is possible to improve mechanical properties such as strength and elastic modulus and wear resistance performance.

The weight average molecular weight of the polyethylene is preferably 700,000 or more and 4.6 million or less. It is more preferably 800,000 or more and 4 million or less, and further preferably 900,000 or more and 3.6 million or less. If the weight average molecular weight is less than 700,000, when used as a braid, not only is fiber fluffing likely to occur due to local rubbing, but it is also difficult to obtain the tensile strength and elastic modulus described later as a braid. Therefore, it is not preferable. Further, when the weight average molecular weight exceeds 4.6 million, the initial elastic modulus of the obtained polyethylene fiber becomes very high, it is difficult to align the polyethylene fibers at the time of braiding, and single yarn breakage occurs frequently, which is not preferable. As a method for measuring the weight average molecular weight, polyethylene having a low molecular weight is generally obtained by a GPC measurement method, but when the weight average molecular weight is high like the polyethylene of the present invention, column clogging may occur during measurement. , It cannot be easily obtained by the GPC measurement method. Therefore, the weight average molecular weight can be obtained from the value of the ultimate viscosity as described in Chapter 4 of "Polymer Handbook Fourth Edition" (publishing year (1999) of JOHN WILEY).

Weight average molecular weight = 5.365 × 10 ⁴ × (extreme viscosity) ^1.37

It is preferable that the repeating unit of the high-strength polyethylene fiber constituting the braid of the present invention is substantially ethylene. Further, as long as the effects of the present invention can be obtained, not only ethylene copolymer but also ethylene and a small amount of other monomers such as α-olefin, acrylic acid and its derivative, methacrylic acid and its derivative, vinylsilane and its derivative. A copolymer with a derivative or the like can be used. Further, these may be copolymers of copolymers, copolymers of ethylene alone polymers, or blends of other homopolymers such as α-olefins. If the ultimate viscosity of the fiber required by the method described later satisfies the above range, for example, polyethylene having a different weight average molecular weight, including a blend of high-density polyethylene and ultra-high molecular weight polyethylene, and a blend of low-density polyethylene and ultra-high molecular weight polyethylene. It may be a blend of low density polyethylene, high density polyethylene and ultra high molecular weight polyethylene. Further, a blend of two or more kinds of ultra-high molecular weight polyethylenes having different weight average molecular weights may be used. Further, a polyethylene blend having a different molecular weight distribution may be used as long as the ultimate viscosity of the fiber obtained by the method described later satisfies the above range.

However, if the content other than ethylene increases too much, it will rather hinder stretching. Therefore, from the viewpoint of obtaining high-strength fibers, the number of branches existing in polyethylene is preferably 3 or less per 1000 main chain carbon atoms. It is more preferably 2 or less, still more preferably 1.5 or less. Further, the branch length at this time is preferably shorter than that of the butyl branch. The measurement method will be described in detail in Examples.

The method for producing the high-strength polyethylene fiber constituting the braid of the present invention is not particularly limited, but the following solution molding method is preferable. Several known solution molding methods are known and are not particularly limited, but polyethylene is dissolved in a volatile organic solvent such as decalin or tetralin which is a solvent for polyethylene or a non-volatile solvent such as paraffin to form a fiber. It is preferable to use a solution spinning method for forming into a shape.

The concentration when dissolving polyethylene is preferably 0.5 wt% or more and 40 wt% or less, more preferably 2.0 wt% or more and 30 wt% or less, and further preferably 4.0 wt% or more and 20 wt% or less. If the concentration of polyethylene is less than 0.5 wt%, the production efficiency is very poor, which is not preferable. On the other hand, when the concentration of polyethylene exceeds 40 wt%, it is not preferable because the molecular weight is very large and it becomes difficult to discharge from the nozzle described later in the solution spinning method.

The high-performance polyethylene fiber constituting the braid of the present invention is extruded after uniformly melting the above-mentioned polyethylene solution at 10 ° C. or higher, preferably 20 ° C. or higher, more preferably 30 ° C. or higher than the melting point using an extruder or the like. It is supplied to the spinning nozzle (spinning cap) using a fixed quantity feeding device.

One of the important configurations in the present invention is to include 10 ppm or more of low melting point polyolefin in the fiber before the spinning step, during the spinning step, or after the spinning step. The melting point of the low melting point polyolefin is preferably 70 ° C. or higher and 100 ° C. or lower, more preferably 75 ° C. or higher and 95 ° C. or lower. The low melting point polyolefin contained may be extracted and adjusted to a predetermined content using an extractant after the spinning step.

Then, the nozzle orifice having a diameter of 0.2 to 3.5 mm, preferably 0.5 to 2.5 mm in diameter is discharged at a discharge rate of 0.1 g / min or more. Next, the discharge molded product is cooled to 5 to 60 ° C. and then taken up at 800 m / min or less. Further, in the spinning stage, it is preferable that the temperature of the spinneret is 10 ° C. or higher from 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 to be picked up at a rapid rate. Further, at a temperature equal to or higher than the boiling point of the solvent to be used, the solvent boils immediately after the spinneret is ejected, so that yarn breakage frequently occurs immediately below the spinneret, which is not preferable. The cooling method may be 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.

The discharged gel yarn is deformed at a magnification of 1.1 times or more and 100 times or less by the time the discharged gel yarn is completely thinned in the cooling step. It is preferably 2.0 times or more and 80 times or less, and more preferably 5.0 times or more and 50 times or less. At this time, it is important that the time required for deformation is within 3 minutes. It is preferably within 2 minutes, more preferably within 1 minute. If the time required for deformation exceeds 3 minutes, the polyethylene molecular chains inside the discharged gel yarn are relaxed, and not only is it impossible to obtain a braid with high strength and high elastic modulus, but also the braid of the present invention is characteristic. It is not possible to achieve both the characteristic dimensional stability and high tensile strength and elastic modulus. Therefore, it is not possible to obtain the physical property retention rate with little change with time, which is desired for such applications, which is not preferable. At this time, a part of the solvent in the discharged gel thread may be removed in the process of deforming the discharged gel thread.

The undrawn yarn obtained by cooling is heated and drawn several times while removing the solvent, and in some cases, multi-stage drawing is performed. As a means for removing the solvent, the above-mentioned heating method may be used in the case of a volatile solvent, but in the case of using a non-volatile solvent, a method of extracting with an extractant or the like can be mentioned. As the extractant, for example, chloroform, benzene, trichlorotrifluoroethane (TCTFE), hexane, heptane, nonane, decane, ethanol, higher alcohol and the like can be used. At this time, it is important that the content of the low melting point polyolefin is not less than 1 ppm. Further, as the heat medium in the stretching step, an inert gas such as air or nitrogen, water vapor, a liquid medium or the like may be used, or stretching may be performed using a heating roller. At this time, it is not necessary to simultaneously perform the desolvation step and the drawing step of the undrawn yarn, and the undrawn yarn may be drawn in one or more steps after being dried. Of course, it may be stretched while removing the solvent. At this time, one of the important configurations for producing the braid of the present invention is the residual amount of the low melting point polyolefin in the fiber before the string making process. The residual amount is preferably 1 ppm or more and 1% or less. It is preferably 10 ppm or more and 0.5% or less, and more preferably 50 ppm or more and 0.1% or less. If the residual amount of the low melting point polyolefin exceeds 1%, the strength of the obtained braid is low and the dimensional stability near room temperature is low, which is not preferable. Further, if it is less than 1 ppm, the molding processability in the string making process is poor and single yarn breakage occurs frequently, which is not preferable.

As an important manufacturing method in the braid of the present invention, one of the elements is a method of drawing polyethylene fibers. Deformation rate at the time of stretching is preferably preferably 0.001 ^-1 0.8s ^-1 or less. More preferably, it is 0.01s ^-1 or more and 0.1s ^-1 or less. The deformation rate can be calculated from the draw ratio of the fiber, the draw rate, and the length of the draw section. That is, the deformation speed (s ^-1 ) = (1-1 / stretching ratio) stretching speed / length of the stretching section. If the deformation rate is too high, the fibers will break before reaching a sufficient draw ratio, which is not preferable. Further, if the deformation rate of the fiber is too slow, the molecular chain is relaxed during drawing, and the fiber becomes thin due to drawing, but a fiber having high physical properties cannot be obtained. As a result, the tensile strength and elastic modulus when braided are increased. It becomes low and is not preferable.

The draw ratio of the undrawn yarn is 10 times or more and 60 times or less, preferably 12 times or more and 55 times or less, and more preferably 15 times or more and 50 times or less in the total draw ratio regardless of whether the drawing step is one step or multiple steps. Recommended. Further, in the stretching step, the polyethylene fibers are preferably stretched at a temperature equal to or lower than the melting point at least once. At this time, when stretching a plurality of times, it is preferable that the temperature at the time of stretching is higher as the process progresses to the latter stage. The stretching temperature at the final stage of stretching is such that the temperature of the polyethylene fiber is 80 ° C. or higher, 160 ° C. or lower, preferably 90 ° C. or higher and 158 ° C. or lower. The conditions of the heating device may be set so that the polyethylene fibers reach this temperature during stretching. At this time, the yarn temperature can be measured using an infrared camera (SC640 manufactured by FLIR systems).

An object of the present invention is to provide a braid having excellent dimensional stability near room temperature, and one of the important elements of the present invention to achieve this is the braid heated to 80 ° C. or higher. The rate of cooling the drawn yarn to 50 ° C. is preferably 3 ° C./sec or more and 500 ° C./s or less. It is preferably 10 ° C./sec or more and 400 ° C./s or less, and more preferably 20 ° C./sec or more and 300 ° C./s or less. By cooling from the temperature at the time of stretching to 50 ° C. for a time within a predetermined range, the residual strain at the time of stretching can be maintained. 50 ° C. is a temperature sufficiently lower than the crystal dispersion temperature of the polyethylene fibers, and by setting the temperature to 50 ° C. or lower, it is possible to develop the tightness between the fibers, which is important during the heat treatment in the braid processing described later. When the cooling rate of the drawn yarn is less than 3 ° C./sec, the molecular chains of the fibers are relaxed, so that the tightening between the fibers is insufficient in the subsequent string making process, and the braid has poor dimensional stability, which is not preferable. On the other hand, if the cooling rate of the drawn yarn after the drawing exceeds 500 ° C./s, the residual strain of the drawn yarn after cooling becomes too large, resulting in the braid after the string making process becoming hard. Therefore, it cannot be used in applications requiring flexibility such as fishing line, which is not preferable. Examples of the cooling method include a water bath bath having a temperature of 50 ° C. or lower. Further, as another cooling means, for example, a cooling method by contacting with a roller having a surface temperature of 50 ° C. or lower may be used. At this time, the fibers may be cooled by using a plurality of rollers to lower the surface temperature of the rollers toward the later stage. For example, when cooling with three rollers having different temperatures, the fiber is cooled in the order of the roller surface temperature immediately after stretching at 80 ° C., the second roller surface temperature at 60 ° C., and the third roller surface temperature at 30 ° C. You may use the means to do. Cooling air using air or an inert gas may be used as another means, and there is no limitation as long as the conditions satisfy the above-mentioned cooling rate.

As one of the important elements of the present invention, the cooled yarn is preferably wound with a tension of 0.001 cN / dtex or more, 7.0 cN / dtex or less, more preferably 0.05 cN / dtex or more and 3 cN / dtex or less. Take is mentioned. By winding in this range, it is possible to wind the polyethylene fiber while maintaining the residual strain. If the take-up tension is less than 0.001 N / dtex, the residual strain becomes small, which is not preferable. Further, when the winding tension is 7.0 cN / dtex or more, single yarn breakage of the fiber is likely to occur, which is not preferable. The fiber temperature at the time of winding is preferably 60 ° C. or lower. It is more preferably 50 or less, still more preferably 45 ° C or less. If the temperature at the time of winding exceeds 60 ° C., the residual strain fixed in the above-mentioned cooling step is relaxed, which is not preferable.

The braid of the present invention is preferably composed of three or more fibers, that is, three or more fibers. If the number of strings is two or less, the shape of the braid will not be formed, and the contact area with the guide or the like will be large. As a result, the wear resistance will be deteriorated and the smoothness when moving the braid will be impaired. Further, the braid of the present invention needs to be a high-strength polyethylene fiber having one or more of the fibers constituting the braid having the physical properties of the present invention. By using the high-strength polyethylene fiber as a constituent fiber, it is possible to maintain high strength and high elastic modulus, and to reduce dimensional stability and fluctuation of mechanical properties with time. If one or more of the constituent fibers are the high-strength polyethylene fibers, fibers of other materials such as polyester fiber, polyamide fiber, liquid crystal polyester fiber, polypropylene fiber, acrylic fiber, aramid fiber, metal fiber, inorganic fiber, natural fiber, It may be a composite with recycled fibers. Further, the fibers other than one high-strength polyethylene fiber may be a multifilament or a monofilament, may be a composite with a short fiber, and the polyethylene fiber itself may be molded into a tape or ribbon shape. You may use a split yarn created by splitting the body. The single yarn shape of each fiber may be circular or irregular, and can be selected from a hollow shape, a flat shape, and the like. In addition, a part or all of each fiber may be colored or fused, and if desired, an antioxidant, a heat stabilizer, a flame retardant, a surfactant, an optical brightener, a surface modifier, and an antibacterial agent. , Anti-corrosion agent, abrasion modifier, antistatic agent, light-resistant stabilizer, ultraviolet absorber, plasticizer and other additives may be added.

Further, the tensile strength of the braid is more preferably 8 cN / dtex or more, still more preferably 20 cN / dtex or more. The upper limit of the tensile strength is not particularly limited, but it is technically and industrially difficult to obtain a braid having a tensile strength exceeding 50 cN / dtex. The initial elastic modulus is preferably 150 cN / dtex or more and 1800 cN / dtex or less. More preferably, it is 250 cN / dtex or more and 1400 cN / dtex or less, and further preferably 350 cN / dtex or more and 1300 cN / dtex or less. If it has such tensile strength and initial elastic modulus, it is difficult for physical properties and shape changes to occur with respect to external force when it is used as a product.

The stress at 1% extension of the braid according to the present invention is preferably 0.5 cN / dtex or more and 20 cN / dtex or less. More preferably, it is 0.8 cN / dtex or more and 12 cN / dtex or less, and further preferably 1.0 cN / dtex or more and 10 cN / dtex or less. When the stress at the time of 1% stretching is less than 0.5 cN / dtex, for example, when it is used as a fishing thread, it is not preferable because the fish's atari is not transmitted to the hand. On the other hand, if the stress at 1% elongation exceeds 15 cN / dtex, for example, when used as a fishing thread, even a slight disturbance is transmitted to the hand as stress, so it is difficult to distinguish between fish and noise. It is not preferable.

The tensile strength of the fiber unwound from the braid in the present invention is 15 cN / dtex or more, more preferably 20 cN / dtex or more, still more preferably 22 cN / dtex or more. The upper limit of the tensile strength is not particularly limited, but it is technically and industrially difficult to obtain a braid having a tensile strength exceeding 50 cN / dtex.

As the braiding method of the braid of the present invention, the braiding angle is 6 to 35 °, preferably 15 to 30 °, and more preferably 18 to 25 °. If the braiding angle is less than 6 °, the shape of the braid becomes unstable and the cross section tends to be flat. In addition, the stiffness of the braid is low, which significantly impairs product performance. Further, when the assembling angle exceeds 35 °, the morphology becomes stable, but on the other hand, the retention rate of the tensile strength of the cord with respect to the tensile strength of the raw yarn decreases, which is not preferable. However, in the present invention, the assembling angle is 6 to 35 °. It is not limited to the range of.

The braid of the present invention is made of three or more fibers, but the present invention is not particularly limited, but the use of three or more fibers and 16 or less fibers is preferably used. The constituent fibers include one or more of the above-mentioned polyethylene fibers, and may be composed of long fibers, short fibers, and monofilaments of other materials as long as the mechanical properties of the braid satisfy the above range. As the other material, for example, not only organic fibers such as polyamide fibers, polyester fibers, liquid crystal polyester fibers, acrylic fibers and PBO fibers, but also metal fibers and inorganic fibers may be used.

Furthermore, one of the important configurations of the present invention is mentioned in the post-treatment method after the string-making process described above. Specifically, it is the temperature, time, tension at the time of heat-treating the braid that has passed the above-mentioned braiding process, and the temperature and tension at the time of winding process.

The heat treatment is preferably performed at 70 ° C. or higher for 0.1 seconds or longer and 30 minutes or shorter, preferably 90 ° C. or higher, and more preferably 100 ° C. The upper limit of the processing temperature is 160 ° C. or lower. When the temperature of the heat treatment is less than 70 ° C., single yarn breakage increases when passing through the process in a tensioned state, which is not preferable. Further, if the heat treatment temperature exceeds 160 ° C., not only the braid is likely to be broken (fused), but also the desired mechanical properties of the braid cannot be obtained, which is not preferable. The treatment time is preferably 0.5 seconds or more and 25 minutes or less, and more preferably 1.0 seconds or more and 20 minutes or less. If the treatment time is less than 0.1 seconds, tightening due to residual strain of the fiber becomes insufficient, which is not preferable. Further, if the heat treatment time exceeds 30 minutes, not only the braid is likely to be broken, but also the desired mechanical properties of the braid cannot be obtained, which is not preferable.

It is preferable that the tension applied to the braid during heating after braiding, which is an important element in the present invention, is 0.005 cN / dtex or more and 15 cN / dtex or less. It is more preferably 0.01 cN / dtex or more and 12 cN / dtex or less, and further preferably 0.05 cN / dtex or more and 8 cN / dtex or less. In the heat treatment step, it is important to obtain the braid according to the present invention within the above ranges of the three elements of the treatment temperature, the treatment time, and the treatment tension. For example, when the tension during processing is larger than the above range, the braid during the process is broken, the mechanical properties of the obtained braid are lowered, the dimensional stability is lowered, or the mechanical properties with time are reduced. It is not preferable because the fluctuation becomes large.

The heating method at the time of heat treatment is not particularly limited. Known methods such as a hot bath in which a resin is dispersed or dissolved in water, an oil bath, a hot roller, a radiant panel, a steam jet, a hot pin, and the like are recommended, but are not limited thereto. After braiding or during braiding, twisting, resin addition, or coloring may be desired if desired. Further, during the heat treatment step, it may be re-stretched to 1.05 times or more and 15 times or less. When the re-stretching ratio is less than 1.05 times, the braid is loosened in the heat treatment step, which is not preferable. Further, if the redrawing ratio exceeds 15 times, the fibers constituting the braid are broken, which is not preferable.

One of the important configurations in the present invention is that the amount of elongation of the polyethylene fiber after unwinding from the braid after 2 hours under a load of 70 ° C. and 5 cN / dtex is 5.0% or more. It is preferably 6.0% or more, more preferably 8.0% or more. When a fiber having an elongation amount of less than 5.0% under this condition is used, single yarn breakage during braid molding increases, which is not preferable.

Further, one of the important configurations in the present invention is that the braid has high dimensional stability near room temperature. That is, it is necessary that the polyethylene fibers after being unwound from the braid have excellent dimensional stability near room temperature. Specifically, the shrinkage rate is 0.40% or less, preferably 0.35% or less, and more preferably 0.3% or less even after 240 hours have passed in an environment of 40 ° C. With this value, it is possible to maintain dimensional stability and maintain strength and elastic modulus as a braid even when stored for a long period of time in a warehouse, a car, or the like.

The characteristics of the polyethylene fiber obtained in the present invention were measured and evaluated as follows.

(1) Extreme viscosity Extrapolation to the origin of a straight line obtained by measuring the specific viscosities of various dilute solutions with a Ubbelohde-type capillary viscosity tube with decalin at 135 ° C. and approximating the minimum square of the plot to the concentration of the viscosity. The ultimate viscosity was determined from the points. During the measurement, the sample was divided or cut into lengths of about 5 mm, 1% by mass of antioxidant (trade name "Yoshinox BHT" manufactured by Yoshitomi Pharmaceutical Industries, Ltd.) was added to the polymer, and the temperature was 135 ° C. for 24 hours. The measurement solution was prepared by stirring and dissolving.

(2) Fineness The sample was cut into 1 m at 5 different positions, the weight was measured, and the fineness was determined using the average value.

(3) Strength, elongation, elastic modulus, stress at 1% extension Measured according to JIS L1013 8.5.1. For strength and elastic modulus, use "Tencilon Universal Material Testing Machine" manufactured by Orientec Co., Ltd., and set a strain-stress curve at an atmospheric temperature of 20 ° C. under the conditions of a sample length of 200 mm (chuck length) and an elongation rate of 100% / min. , Measured under 65% relative humidity, strength (cN / dtex) from stress and elongation at break point, elongation (%), elastic modulus (cN / dtex) from tangent to give maximum gradient near the origin of the curve Was calculated and calculated. At this time, the initial load applied to the sample at the time of measurement was set to 1/10 of the fineness. For each value, the average value of the measured values of 10 times was used. This measurement can be used for both braids and threads unwound from braids.

(4) Measurement of shrinkage rate The measurement was performed according to the method of dry heat shrinkage rate (b), JIS L1013 8.18.2. The measurement fiber sample and the braid sample were cut to 70 cm and marked at positions 10 cm from both ends, that is, the sample length was 50 cm. Next, the fiber sample and the braid sample were heated in a hot air circulation type heating furnace at a temperature of 80 ° C. for 240 hours in a state of being suspended so as not to apply an extra load. Then, the fiber sample was taken out from the heating furnace, slowly cooled to room temperature, and then the length of the position where the fiber sample and the braid sample were first marked was measured. The shrinkage rate can be calculated from the following formula.

Shrinkage rate (%) = 100 × (length of fiber sample and braid sample before heating-length of fiber sample and braid sample after heating) / (length of fiber sample and braid sample before heating)

For each value, the average value of the two measured values was used.

(5) Elongation amount after 2 hours under a load of 70 ° C. and 5 cN / dtex A load of 10% of the breaking load was applied to a position where the change in the length of the multifilament on the heater could be seen, and marks were made at intervals of 50 cm. The thread 1 m unwound from the braid was brought into contact with a metal heater having a length of 60 cm heated to 70 ° C. to fix one thread end, and then the other thread end was loaded with the above-mentioned predetermined load. In order to remove the effect of initial elongation when a load is applied and to measure only the amount of strain over time, the length after 5 minutes have passed at 50 ° C or 70 ° C, which is the same temperature as the measurement temperature, after the load is applied. Let it be the length of the multifilament at 0 hours. Then, the length of the multifilament after 2 hours was measured, and the amount of strain after 2 hours was determined using the following formula.

Amount of strain after 2 hours (%) = 100 x (length after 2 hours (cm) -5 minutes after elapse (cm)) / 50 cm

(6) Residual amount of low melting point polyolefin Gas chromatography (manufactured by Shimadzu Corporation) was used to measure the residual solvent concentration in the fiber sample. 10 mg of sample fiber was set in the glass insert of the gas chromatography inlet. The injection port was heated above the boiling point of the solvent, and the solvent volatilized by the heating was introduced into the column by nitrogen purging. The column temperature was set to 40 ° C. and the solvent was trapped for 5 minutes. Next, the measurement was started after raising the column temperature to 80 ° C. The residual solvent concentration was determined from the obtained peak.

Examples will be illustrated below to describe the present invention in detail, but the present invention is not limited thereto.

(Example 1)
A dispersion of ultra-high molecular weight polyethylene and liquid paraffin having an ultimate viscosity of 10.5 dL / g and a weight average molecular weight of 1,410,000 was prepared to have a polyethylene concentration of 8.0 wt%. This dispersion was made into a solution at 190 ° C. by an extruder, and the polyethylene solution was discharged from a spinneret having an orifice diameter of φ1.0 mm and 30H at a nozzle surface temperature of 180 ° C. and a single-hole discharge rate of 2.0 g / min. By the time the discharged yarn was solidified, it was deformed 8 times and cooled in a water-cooled bath at 30 ° C., and liquid paraffin in the discharged yarn was continuously extracted using methylene chloride to obtain an undrawn yarn. The time required for the deformation at this time is 0.5 minutes. Subsequently, before stretching the undrawn yarn, a solution prepared by dissolving paraffin having a molecular weight of 1800 in decalin heated to 80 ° C. was applied to the undrawn yarn at a ratio of 0.1 wt%, and hot air at 110 ° C. was applied. It was stretched 4.0 times while being heated and dried in. Next, the yarn was stretched 5.0 times in 40 seconds under hot air at 150 ° C., continuously cooled rapidly using a water bath, and the drawn yarn was immediately cooled and wound. The cooling rate up to 50 ° C. at this time was 20 ° C./sec. The temperature at the time of winding the drawn yarn was 30 ° C., and the tension was 0.10 cN / dtex. These stretching and cooling steps were carried out continuously.
Using four of the undrawn yarns, stringing was performed as four-on-the-floor. After the string-making process, heat treatment was continuously performed at 145 ° C. and a tension of 1.90 cN / dtex for 4 minutes. The draw ratio of the braid at this time is 1.1 times. The heat-treated braid was wound at 30 ° C. Table 1 shows the physical properties of the obtained braid.

(Comparative Example 1)
A dispersion of ultra-high molecular weight polyethylene and decalin having an ultimate viscosity of 17.0 dL / g and a weight average molecular weight of 2,800,000 was prepared to have a polyethylene concentration of 9.0 wt%. This dispersion was made into a solution at 205 ° C. using an extruder, and the polyethylene solution was discharged from a spinneret having an orifice diameter of φ1.0 mm and 30H at a nozzle surface temperature of 180 ° C. and a single-hole discharge rate of 2.0 g / min. By the time the discharged yarn was solidified, it was deformed 16 times and cooled in a water-cooled bath at 30 ° C. to obtain an undrawn yarn. The time required for the deformation at this time is 0.1 minutes. Subsequently, the undrawn yarn was stretched 4.0 times while being heated and dried with hot air at 120 ° C. Next, the yarn was stretched 4.1 times in 40 seconds with hot air at 150 ° C., continuously cooled rapidly using a water bath, and the drawn yarn was immediately cooled and wound. The cooling rate up to 50 ° C. at this time was 20 ° C./sec. The temperature at the time of winding the drawn yarn was 30 ° C., and the tension was 0.10 cN / dtex. These stretching and cooling steps were carried out continuously.
Using four of the undrawn yarns, stringing was performed as four-on-the-floor. After the string-making process, heat treatment was continuously performed at 144 ° C. and a tension of 1.90 cN / dtex for 4 minutes. The draw ratio of the braid at this time is 2.1 times. The heat-treated braid was wound at 32 ° C. Table 1 shows the physical properties of the obtained braid.

The braid of the present invention has high dimensional stability even when stored at a high temperature for a long period of time, and makes it possible to reduce fluctuations in mechanical properties with time. As a result, the braid of the present invention is suitable not only for long-term storage but also for long-term use, for example, fishing thread, blind cord, pleated cord, and pleats that require lifting and opening / closing. Demonstrates excellent performance as various interior cord nets such as net door cords, curtain strings, light-shielding screens, protective materials, surgical sutures, meat tightening threads, safety gloves, safety ropes, fishing ropes, finishing ropes, western bow strings, etc. It is something to do. Further, the braid of the present invention is not limited to the above-mentioned molded processed products, and can be widely applied to industrial applications as a base material for collecting organic substances and inorganic substances by combining with various materials, a base material for water retention, and the like.

Claims (2)

A state in which polyethylene having an ultimate viscosity [η] of 5.0 dL / g or more and 30 dL / g or less and whose repeating unit is 90% or more of ethylene is spun and contains 10 ppm or more of a paraffin-based compound having a molecular weight of 100 or more after the spinning process. Then, after further drawing at a temperature of 80 ° C. or higher, the drawn yarn was cooled at a cooling rate of 3 ° C./sec or higher, and the obtained drawn yarn was wound with a tension of 0.001 to 7 cN / dtex. The fibers are twisted as desired, and in the next string-making process, the polyethylene fibers constituting the braid are heated to temperatures of 70 ° C. or higher and 160 ° C. or lower for 30 minutes or less, and the polyethylene fibers are heated during heating. A method for producing a braid, wherein the tension is 0.005 cN / dtex or more and 15 cN / dtex or less. The method for manufacturing a braid according to claim 1, wherein the braid is stretched 1.05 times or more and 15 times or less at 160 ° C. or less after the string is made.