JP2015030935A - Polymethylpentene monofilament and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymethylpentene monofilament a high strength of 4.0 cN/dtex or higher suitable for industrial applications.SOLUTION: A polymethylpentene monofilament of a single fiber fineness of 20-30,000 dtex and a tensile strength of 4.0-7.0 cN/dtex is obtained by discharging a molten polymethylpentene polymer from a nozzle into a liquid bath to cool and drawing in two or more stages to wind under conditions of a spinning draft of 0.7-4.0, a draw ratio in the first stage of 4.5 times or greater and a total draw ratio of 7 times or greater. The monofilament after the drawing is treated in a relaxation ratio of 0.80-0.95 time and then wound.

Description

  The present invention relates to a polymethylpentene monofilament having excellent light weight, chemical resistance, and heat-and-moisture resistance and strength suitable for industrial use, and a method for producing the same.

  Monofilaments containing thermoplastic resins as constituent components are being developed for various industrial applications because of their good processability and productivity.

  In particular, monofilaments made of polyolefin resins such as polyethylene and polypropylene are lightweight, inexpensive, and have excellent hydrolysis resistance, so they are processed into ropes, knitted fabrics, fabrics, etc., marine materials, various filters, conveyor belts, insect-proof fabrics, construction Widely used in applications such as materials, vehicle materials, civil engineering materials, papermaking materials, cushion materials, living materials, agricultural materials.

  However, polyolefin resins represented by polyethylene, polypropylene and the like have a problem that heat resistance is low and the use environment is limited.

  In response to the problems of polyethylene and polypropylene, polymethylpentene mainly composed of 4-methyl-1-pentene not only has a specific gravity of 0.83 g / cc and is lighter than other polyolefins, but also has a high melting point. Since it has the characteristic (for example, 200 degreeC or more), it is a raw material which industrial fiberization is strongly desired, and the method for obtaining a polymethylpentene fiber is proposed by patent documents 1-3.

  For example, Patent Document 1 discloses that melt spinning and hot drawing are possible by using a copolymer of methylpentene and another α-olefin having a melt flow rate of 30 to 200 g / 10 min, and a fineness of 4 to 6 denier is not yet used. It is described that a drawn yarn can be drawn to obtain a polymethylpentene fiber having a fineness of 3 to 6 g / d and a fineness of 1.8 to 3.5 denier.

  Patent Document 2 discloses one copolymer selected from 4-methyl-1-pentene and other α-olefins, and two types selected from 4-methyl-1-pentene and other α-olefins. A method of obtaining a polymethylpentene monofilament having a strength of 3.2 to 4.2 g / d and hardly generating cracks during weaving by using a blend of the above copolymer as a raw material is described.

  Patent Document 3 describes a method for obtaining a polymethylpentene fiber having a strength of 2.9 to 3.5 g / d by once heat-treating a polymethylpentene undrawn yarn taken at 1000 m / min and then drawing. Has been.

JP-A-3-27113 JP-A-8-41725 Japanese Patent Laid-Open No. 11-323657

  The above-mentioned Patent Document 1 describes a method of achieving a strength of 6 g / d with a fineness polymethylpentene fiber considered to be a multifilament obtained by air-cooled spinning. The disclosed polymethylpentene monofilament having a large fineness has low strength, and a polymethylpentene monofilament suitable for industrial use has not been obtained.

  This invention makes it a subject to obtain the polymethylpentene monofilament which achieves the intensity | strength more than 4.0 cN / dtex (= 4.5 g / d) which can be used suitably for an industrial use with respect to the subject mentioned above.

  As a result of the present inventor's various studies on the spinning process of polymethylpentene monofilament, the conventional polymethylpentene monofilament spinning method cannot stretch the undrawn yarn uniformly and at a high magnification, and the cause is from the die. The inventors have found that this is caused by a process of cooling and stretching the polymethylpentene polymer that has been melted and discharged, and reached the present invention.

  That is, the polymethylpentene monofilament achieved by the present invention has a single yarn fineness of 20-30000 dtex and a tensile strength of 4.0-7.0 cN / dtex. The production method is a method for producing a polymethylpentene monofilament in which a melted polymethylpentene polymer is discharged from a die and cooled in a liquid bath, and then drawn and wound in two or more stages. 7 to 4.0, and the first stage draw ratio is 4.5 times or more and the total draw ratio is 7 times or more.

  In the production method of the present invention, the distance between the die surface of the die that discharges the melted polymethylpentene polymer and the liquid bath to be cooled is 20 to 300 mm, and the monofilament after stretching has a relaxation ratio of 0.80. It is a preferred embodiment that the film is wound after being treated at a magnification of ˜0.95.

  According to the present invention, a light-weight and high-strength polymethylpentene monofilament suitable for industrial use can be obtained. By using the high-strength polymethylpentene monofilament, lightness, heat resistance, chemical resistance, Rope, knitted fabric, and other marine products with excellent hydrolysis resistance, various filters, conveyor belts, insect-proof fabrics, building materials, vehicle materials, civil engineering materials, papermaking materials, cushion materials, living materials, agricultural materials, etc. Can be obtained.

  The present invention is described in detail below.

  The single yarn fineness of the polymethylpentene monofilament of the present invention is required to be 20 dtex or more, preferably 100 dtex or more. When the single yarn fineness is less than 20 dtex, the abrasion resistance and rigidity required as a monofilament are impaired, and even if it is a high-strength polymethylpentene filament, it is difficult to use it suitably for industrial use as a monofilament. Become. On the other hand, although the upper limit of the fineness is not limited, the upper limit of fineness obtained with the current technical level is preferably 30000 dtex, because the inner and outer layer differences of the fiber structure are likely to occur in the cooling, stretching and other steps as the fineness increases. Can illustrate 15000 dtex.

  The polymethylpentene monofilament of the present invention has an unprecedented high strength and needs to have a tensile strength of 4.0 to 7.0 cN / dtex, preferably 4.5 to 7.0 cN / dtex. More preferably, it is 5.0 to 7.0 cN / dtex. When the strength is less than 4.0 cN / dtex, the strength required as an industrial material cannot be obtained when the product is used. On the other hand, the higher the upper limit of strength, the better. However, it is difficult to obtain a polymethylpentene having a strength exceeding 7.0 cN / dtex with good yarn-making property in a process that can be used at present.

  The polymethylpentene monofilament of the present invention is also characterized by low thermal shrinkage and excellent thermal dimensional stability, and preferably has a boiling water shrinkage of 1 to 10%. This feature has the advantage that a product with small dimensional change and excellent quality can be obtained even when heat treatment is carried out during the production process of fabrics, nets, ropes and the like.

  The polymethylpentene monofilament of the present invention preferably has excellent dimensional accuracy. For example, in a round cross-section yarn, the flatness indicated by the ratio of the maximum diameter to the minimum diameter in the circumferential direction is 1.0 to 1.2. It is preferable.

  The cross-sectional shape of the polymethylpentene monofilament of the present invention is not particularly limited, and may be a shape such as an ellipse, a square, a polygon, and a multi-leaf cross section as well as the round cross section described above.

  The production method for obtaining the above-described polymethylpentene monofilament of the present invention will be described below.

  Since the polymethylpentene monofilament of the present invention can be produced by a spinning method using a conventionally known extrusion equipment, it can be produced with high productivity and at low cost. In other words, it is manufactured by measuring polymethylpentene polymer melted by an extruder with a gear pump, discharging it from a base attached to a spin pack, cooling it in a liquid bath, and drawing and winding it in two or more stages. The

  The polymethylpentene polymer used as a raw material for the polymethylpentene monofilament of the present invention is a homopolymer consisting only of 4-methyl-1-pentene or a polymer obtained by copolymerizing α-olefin with 4-methyl-1-pentene. . In addition, it is preferable that the ratio of the alpha olefin at the time of setting it as a copolymer is 10 mol% or less from a heat resistant viewpoint.

  The α-olefin to be copolymerized preferably has 2 to 22 carbon atoms, and includes 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, 1-eicosene, and 1 -A dococene etc. can be illustrated.

  The polymethylpentene polymer has a range that does not impair the effects of the present invention, specifically, a matting agent such as titanium oxide, calcium carbonate, kaolin, and clay, pigment, dye, lubricant, and antioxidant as long as it is 5% by mass or less. , A heat-resistant agent, a heat-resistant agent, a light-resistant agent, an ultraviolet absorber, an antistatic agent and a flame retardant.

  When adding functions to polymethylpentene monofilament, imparting light resistance, imparting antibacterial properties, etc., a master chip containing a high concentration of desired pigments, light resisting agents, antibacterial agents, etc. is prepared in advance. A necessary amount of the pentene polymer can be blended for spinning.

  The set temperature of the extruder, spin head, etc. is set based on the melting temperature of the polymer, but it suppresses physical property deterioration due to thermal decomposition, suppresses unevenness of the inner and outer layer structure of undrawn yarn, secures stretchability, and ensures that it is used in a cooling bath. The temperature is preferably 250 to 310 ° C. from the viewpoint of ensuring running yarn stability.

  After the polymer melted by the extruder is introduced into the spinning pack, it is discharged from the spinneret. However, in order to remove foreign matter in the molten polymer and improve the stretchability of the filament, the inside of the pack is made using a metal mesh, metal nonwoven fabric, etc. It is preferable to remove the foreign matter by filtering with a filter.

  In order to remove the structural distortion of the filament inner and outer layers generated in the die hole, the molten filament discharged from the die preferably has a heating cylinder arranged immediately below the die and passed therethrough. The length of the heating cylinder is not particularly limited, but is preferably in the range of 10 to 150 mm from the viewpoint of ease of equipment installation and reduction of fineness unevenness in the longitudinal direction of the obtained monofilament, and the temperature of the heating cylinder Is preferably 250 to 300 ° C.

  The molten filament that has passed through the heating cylinder is cooled and solidified using a refrigerant. However, in the production method of the present invention, it is necessary to cool in a liquid bath using cold / hot water, polyethylene glycol, or the like as a refrigerant. By cooling using a liquid bath, it becomes possible to obtain a monofilament having a large single yarn fineness as in the present invention instantaneously and an unstretched filament having a uniform structure difference between the inner and outer layers. On the other hand, when using an air cooling method generally employed in melt spinning of single fine yarn, the inner and outer layer structure difference of undrawn yarn becomes non-uniform in a filament with a single yarn fineness as in the present invention, As a result, a high-strength monofilament cannot be obtained.

  In the melt spinning of polymethylpentene monofilament, the distance between the base surface of the base for discharging the melted polymethylpentene polymer and the liquid surface of the liquid bath to be cooled is preferably 20 to 300 mm, more preferably. A range of 70 to 200 mm can be exemplified as the range. Although the detailed mechanism is not clear, when the distance between the base surface and the liquid surface is too wide, the stretchability / spinning property tends to decrease with the yarn swing of the discharge filament, while the base If the distance between the surface and the liquid surface is too small, the resulting unstretched monofilament has unevenness in the direction perpendicular to the fiber axis, and the stretchability / spinning property tends to decrease.

  The temperature of the cooling bath may be changed according to the roundness, fineness unevenness, etc. of the obtained monofilament, but the range of 10 to 60 ° C. is exemplified as a preferable cooling temperature for obtaining the polymethylpentene monofilament of the present invention. it can.

  Next, the filament after cooling and solidification is taken up by a take-up roll rotating at a desired surface speed to obtain an unstretched filament. The take-up speed may be a speed at which the molten monofilament cools and solidifies in the cooling bath without any difference between the inner and outer layers, and preferably 5 m / min to 50 m / min, but the take-up speed and the speed at which the molten polymer is discharged from the die hole The spinning draft (take-off speed / discharge linear speed) is 0.7 to 4.0, preferably 1.0 to 3.0. When the spinning draft is less than 0.7, due to insufficient spinning tension, the running stability of unstretched polymethylpentene with low specific gravity in the liquid bath decreases, the fiber structure is large in the longitudinal direction, and the stretchability is poor. Only drawn filaments can be obtained. On the other hand, when the spinning draft exceeds 4.0, fineness unevenness in the longitudinal direction is generated in the discharge filament due to insufficient spinnability, and stretchability is lowered.

  In addition, as described above, in order to obtain the polymethylpentene monofilament of the present invention, it is important to control the tension between the base discharge and the take-up roll, so that the polymethylpentene polymer used as a raw material is P = according to ASTM-D1238. The MFR measured at 5 kg, temperature = 260 ° C. is preferably 9-30 g / 10 minutes, more preferably 20-30 g / 10 minutes. By setting the MFR in the above range, an appropriate spinning tension is obtained in the above-described liquid bath cooling step, the running stability of the discharge filament is improved, the fiber structure spot of the undrawn filament, the diameter spot in the longitudinal direction, and the cross section Unstretched filaments that have small directional shape and can withstand high-strength stretching in the subsequent stretching step can be obtained.

  The unstretched filaments taken up by the take-up roll are subjected to a drawing process after being wound up or without being wound up. It should be noted that in the stretching of a polymethylpentene monofilament having a high fineness, the filament is preheated at a temperature suitable for the orientation level before stretching, and is stretched at a stretching ratio suitable for the mobility of the molecular chain, so that the molecular chain is smoothly stretched. It is essential, and in order to achieve smooth molecular chain stretching in the stretching process, the number of stretching stages needs to be two or more. On the other hand, when high-strength stretching is performed by one-stage stretching for the purpose of increasing strength, the stretching of the molecular chain is unreasonable, resulting in the destruction of the fiber structure and whitening of the physical properties. Only low monofilaments can be obtained. Also, if the stretching temperature is set too high to ensure the mobility of the molecular chain, the molecular chain will crystallize before orientation and it will be difficult to stretch, and as a result, the stretchability will decrease and high strength cannot be achieved, and the filament Will be whitened by the destruction of the fiber structure. Further, when the stretching temperature is further increased to stretch the crystallized filament, molecular chain flow occurs, so-called super draw phenomenon without molecular chain orientation occurs, and effective stretching is not performed.

  The draw ratio in the first stage is 4.5 times or more, and preferably 5.0 times or more. If the draw ratio is less than 4.5 times, the whole undrawn filament is not uniformly drawn and oriented, and the drawability is reduced in the second drawing, resulting in yarn breakage and strength reduction. The draw ratio of the first stage may be within a range where the fiber structure is not destroyed by overdrawing at the drawing temperature, specifically, a range where the filament is not whitened by the fiber structure destruction, but is usually 7 times or less. Preferably there is.

  The heating medium used for stretching is not particularly limited, and hot water, a PEG bath, steam, and a dry heat stretching machine can be used, but for the first stage stretching, a safe and sufficient amount of heat is uniform. Hot water can be preferably used from the viewpoint of imparting to the above.

  The first stage stretching temperature may be appropriately changed depending on the first stage stretching ratio, but 70 to 95 ° C. in order to achieve the stretching of 4.5 times or more, which is the production method of the present invention, with good yarn forming properties. It is preferable that

  The polymethylpentene monofilament after completion of the first stage drawing is then subjected to the second stage drawing. The heating medium used in the second stage stretching is not particularly limited, and hot water, a PEG bath, steam, and a dry heat stretching machine can be used as in the first stage stretching. However, in the second-stage stretching where the traveling speed of the filament is increased, dry heat stretching is preferably performed from the viewpoint of preventing liquid bath scattering.

  The stretching temperature of the second stage may be appropriately set according to the fiber structure of the polymethylpentene monofilament obtained by the first stage stretching, and the polymethyl stretched 4.5 times or more by the first stage stretching. As the stretching temperature of the pentene monofilament, a range of 120 ° C to 160 ° C can be preferably used.

  The draw ratio of the second stage is not particularly limited, and is set to such an extent that the fiber structure is not destroyed by overdrawing, specifically, the filament is not whitened by the fiber structure breakage as in the first stage draw. Good.

  The polymethylpentene monofilament that has been subjected to the second stage of stretching can be subjected to a third or more stage of stretching as required. The stretching temperature, the stretching ratio, and the stretching heat medium after the third stage can be set based on the same concept as the second stage stretching.

  In order to obtain a high-strength polymethylpentene monofilament as in the present invention, the total draw ratio obtained by multiplying the draw ratio of each drawing stage is preferably 7 times or more, and more preferably a range of 8 times or more. Can be illustrated. The upper limit of the total draw ratio is not particularly limited, but it is preferable that the total draw ratio is 11 times or less in order to obtain good yarn forming properties using the current monofilament spinning equipment.

  The polymethylpentene monofilament with extremely high strength as in the present invention has a large residual strain in the fiber structure after drawing, and the winding bobbin may be deformed when not subjected to relaxation heat treatment. It is preferable to wind after relaxing heat treatment at a relaxation ratio of 0.80 to 0.95. At this time, the relaxation heat treatment temperature is preferably 100 ° C to 200 ° C.

  The monofilament after the relaxation treatment is wound up by a winder, and at this time, the winding tension is preferably 0.40 cN / dtex or less from the viewpoint of further reducing the residual strain. The lower limit of the winding tension is not limited, but is preferably 0.02 cN / dtex or more in order to obtain a winding package applicable to actual use.

  Thus, the polymethylpentene monofilament of the present invention can be obtained.

  Hereinafter, embodiments of the present invention will be described in more detail by way of examples. In addition, the definition of the characteristic used for the specification text and the examples and the measuring method are as follows. In addition, when it did not touch in particular about the number of measurement n, it measured by n = 1.

  [Outer Diameter] Using a Digimatic standard outer micrometer (Mitutoyo Co., Ltd., MDC-25SB), the outer diameter of the monofilament was measured at 10 points in the length direction, and the average value of the outer diameters obtained was measured as the diameter. It was.

  [Fineness] Measured according to JIS L1013: 2010 8.3.1 B method.

  [Strength, Elongation, Tensile Strength] Using a Tensilon UTM-4-100 type tensile tester manufactured by Orientec Co., Ltd., the strength of monofilaments at a constant speed tension type grip interval of 25 cm in accordance with JIS L1013: 2010 8.5.1 Was measured at three points, and the average strength and average elongation of the trials three times were determined. The strength was obtained by dividing the average strength by the fineness.

  [Boiling water shrinkage (boiling yield)] Measured according to JIS L1013: 2010 8.18.1 (Method B).

  [MFR] Measured according to ASTM D1238 at a load of 5 kg and a temperature of 260 ° C.

  [Yarn-making property] The number of yarn breakage when continuous production for 12 hours is carried out under the production conditions of the examples and comparative examples.

  (Examples 1-5, Comparative Example 2, Comparative Example 4) 280 polymethylpentene resin (Mitsui Chemicals Co., Ltd., RT31, MFR = 21 g / 10 min, melt density at 260 ° C. = 0.72 g / cc) After melting with a uniaxial extruder having a diameter of 40 mm set at ° C., it was weighed so as to have the fineness shown in Table 1 using a gear pump kept at 280 ° C. and introduced into a spinning pack kept at 280 ° C. The molten polymer was filtered through a 200-mesh metal filter in the pack, and then discharged from a die having a hole diameter of 1.5 mm, a hole length of 3.0 mm, and a number of holes of 4. The discharge filament passes through a 70 mm long heat insulating cylinder attached directly under the base, and then passes through a cooling water bath of 20 ° C. installed with a base surface and a liquid surface distance shown in Table 1, and as shown in Table 1. The unstretched monofilament was taken up by a take-up roll (1R) rotating at a surface speed of. After unwinding the unstretched monofilament, it is placed between 1R and the second roll (2R) and stretched in the first stage at a magnification described in Table 1 using a hot water tank adjusted to 90 ° C. The second-stage stretching was performed using a dry heat stretching tank installed between 2R and the third roll (3R) and adjusted to 140 ° C. so as to achieve the total magnification shown in Table 1. The stretched monofilament is placed between 3R and the 4th roll (4R), subjected to relaxation heat treatment at a magnification shown in Table 1 using a dry heat bath adjusted to 150 ° C., and a winding tension of 0.15 cN Then, it was wound around a DIN200 type bobbin made of ABS resin with a winding amount of 1.5 kg. The properties of the obtained monofilament were as shown in Table 1.

  (Example 6, Comparative Example 3) After winding the unstretched monofilament taken up at 1R rotating at the surface speed shown in Table 1, the surface speed was changed to 15 m / min and the magnification shown in Table 1 was obtained. Example 1 except that the first stage of stretching was performed between 2Rs rotating at various surface speeds, and then the second stage of stretching was performed between 2R and 3R so as to achieve the total magnification described in Table 1. The same was done.

  (Example 7) It carried out like Example 6 except having used the nozzle | cap | die of hole diameter 3.0mm, hole length 5.0mm, and the number of holes 4.

  (Example 8) The process was performed in the same manner as in Example 1 except that a base having a hole diameter of 0.6 mm, a hole length of 1.2 mm, and a hole number of 20 was used.

  (Comparative Example 1) The temperature of the dry heat stretching tank installed between 2R and 3R was set to room temperature (25 ° C), and the 2R speed and 3R speed were set to the same speed (that is, the stretching was set to only one stage). Except for this, the same procedure as in Example 1 was performed. The properties of the obtained monofilament were as shown in Table 2.

  As described above, the polymethylpentene monofilament of the present invention is higher in strength than the conventional yarn, and in Example 3, the bobbin heel part was deformed after winding, but the production method of the present invention was used. By using it, a high-strength polymethylpentene monofilament could be obtained with good spinning properties.

  Since the polymethylpentene monofilament of the present invention has characteristics of high strength, it is a marine product, various filters, conveyor belts, insect proof fabrics, building materials, vehicle materials, civil engineering materials, papermaking materials, cushion materials, living materials, agricultural materials It can be suitably used as a rope, knitted fabric, woven fabric, etc.

Claims (4)

A polymethylpentene monofilament having a single yarn fineness of 20 to 30000 dtex and a tensile strength of 4.0 to 7.0 cN / dtex. A method for producing a polymethylpentene monofilament in which a melted polymethylpentene polymer is discharged from a die and cooled in a liquid bath, and then drawn and wound in two or more stages, and the spinning draft is 0.7 to 4. A process for producing a polymethylpentene monofilament having 0 and a first stage draw ratio of 4.5 times or more and a total draw ratio of 7 times or more. The method for producing a polymethylpentene monofilament according to claim 2, wherein the distance between the die surface of the die for discharging the molten polymethylpentene polymer and the liquid bath for cooling is 20 to 300 mm. The manufacturing method of Claim 2 or 3 which winds up, after processing the monofilament after the said extending | stretching by the relaxation ratio 0.80-0.95 times.