JP2008106419A - Method for producing polyester fiber for seat belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester fiber for a seat belt which has a high strength, and a small change in entanglement before and after woven in a high density in a needle loom, is excellent in strength retention and process passage rate of raw yarn, and has good entanglement characteristics. <P>SOLUTION: The polyester fiber having a fineness of 1,000 to 2,000 dtex and a single fiber fineness of 2-20 satisfies a relationship: ΔL=¾L1n-L2n¾≤15 (cm), Δσ=¾σ1-σ2¾≤15, wherein L1 (cm) is the tear length of the polyester yarn; L2 (cm) is a tear length of the polyester yarn after subjected to tension at a tension of 2 cN/dtex. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyester fiber that is suitably used for seat belt applications. Specifically, the fiber has high strength, little entanglement change before and after being woven at a high density in a needle loom, and the strength retention rate and process of the raw yarn The present invention relates to a polyester fiber for seat belts having excellent permeability and good entanglement characteristics.

  A seat belt made of polyester fibers is widely used as an occupant restraining device in an automobile or the like. Polyester fibers are usually used as polyester fibers for seat belts. Generally, warp yarns having a fineness of 1100 to 1670 dtex and a single yarn fineness of 10 to 18 dtex are often used. Since the warp of the seat belt is woven at a high density (240 to 300 1670 dtex yarns in a width of about 50 mm) when weaving the belt, it is necessary for the yarns to converge during weaving. Therefore, as described in Patent Document 1, the warp of the seat belt is twisted or entangled by a twisting process after yarn forming or by an entanglement process in the yarn forming process. Entanglement is widely applied because it is less expensive than twist and has the advantage of improving the flexural modulus of the belt. Entanglement is usually performed by blowing air to the yarn that runs with the entanglement nozzle before winding the drawn yarn, but the running speed of the yarn is slow during the entanglement process, and the tension of the yarn during the treatment is low. The lower the yarn, the smaller the fineness of the yarn, and the higher the flow rate of air to be jetted, the higher the entangled yarn.

  However, in general, fibers used as warp yarns for seat belts are large in total fineness and single yarn fineness and are difficult to be entangled in this respect. When the entanglement treatment by air jet is applied, the yarn is damaged by the treatment, the strength of the yarn is reduced, or excessively strong entanglement occurs at the portion where the entanglement occurs, resulting in an undesirable appearance (glare) in the woven fabric. Leading to giving.

  Several methods have been proposed and put into practical use as a method for evaluating confounding, but the confounding numerical value obtained by the evaluation method even for the same yarn (usually expressed by the number of converging parts per meter) It is necessary to pay attention to the fact that the For example, in the EIB of Lawson Hemfill, light is irradiated from one side of a running yarn and the shading of the yarn is measured to recognize the entangled nodes and spread parts and calculate the number of entanglements. In Reutlinger's Interlace Counter Model RICII, instead of using light, the yarn is lightly clamped with a probe, and the entangled nodes and spread are recognized from the thickness of the yarn. Although there is a difference in the detection means of the node / opening part, these measuring devices are basically the same in that the number of confounding is read from the shape of convergence / opening without physically destroying the confounding It is. Although these methods can know the number of confounding, it is basically impossible to know how strong each converging part is confounded, that is, the “strength” of confounding. Another method of knowing the entanglement of the raw yarn is the tear length of the raw yarn. This is because when the raw yarn is divided in the longitudinal direction so that the filaments are roughly halved at any part of the raw yarn, and the filaments divided in half with the left and right fingers are torn apart and spread, The entanglement property is evaluated from the average value of the tear length (equal to the distance between the entangled entanglement points) when no further tearing occurs. In this method, since slight entanglement that gives light convergence to the yarn is evaluated while breaking, the number of entanglement points per 1 m of the raw yarn evaluated by the tear length is obtained by a shadow method by EIB or the like. The number of confounding points is considerably reduced to 1/2 to 1/20. Since the measurement of tear length is often performed by human hands, there is a concern that the measured value differs depending on the measurer.However, when the fiber cannot be torn due to entanglement, the resistance against the tearing force increases rapidly, so the measurer There will be no significant difference in results. As another method, there is a JIS method (so-called hook drop method) in which a hook with a load is hung on an original yarn stretched in a vertical method, and the number of entanglements is obtained from the distance moved until the hook stops. Since an extremely light load (mN) obtained by multiplying the yarn fineness (tex) by 0.22 is used, it can be said that this is an intermediate evaluation method between the shadow method and the tear method.

  Giving entanglement to a conventional yarn for a seat belt having a large single yarn fineness is described in Patent Document 1, for example, and it is described that the entangled portions are arranged at intervals of 5 to 15 cm in length. Yes. However, no specific entanglement imparting method such as a measurement method or a nozzle used for confounding is described, and even if fibers are produced by the method described in Patent Document 1, it is imparted in the seat belt webbing manufacturing process. Due to the tension, the convergence was insufficient and fluff defects were often induced during weaving.

  Further, in Patent Document 2, the number of entanglements and entanglements preferred for weaving are about the original yarn intended for an airbag using fibers having a smaller total fineness and single yarn fineness compared to the seat belt targeted by the present invention. It describes the strength relationship. However, the entanglement strength in Patent Document 2 is an index calculated from the difference between the signal at the converging part and the opening part measured by Interlace Counter Model RICII (Reutlinger). It is not a measure of the strength to be measured. In other words, from the appearance of the entangled part, the difference between the thickness of the converging part and the opening part is clearly called high entanglement strength, for example, if there is a part where the yarn is partially twisted and the yarn has converged, Even in a state where the converging part is easily unwound, it is supposed to have high entanglement strength and evaluation is insufficient. In addition, the invention described in Patent Document 2 is intended for fibers having a small total fineness and single yarn fineness, and depending on the entanglement imparting method, it is particularly difficult to impart sufficient entanglement performance to the raw yarn for seat belt that is difficult to impart. It was impossible at all.

  Further, in Patent Document 3, after the polyester polymer is melt-spun and the yarn is cooled and solidified, an oil agent is applied, and then, when winding through at least two take-up roll groups, the first take-up roll group and A process for producing a polyester fiber is disclosed in which the entangling process is performed between at least two interlace nozzles between the next take-up roll groups, and winding is performed at a spinning speed of 5000 m / min or more. However, in the method described in Patent Document 3, since the entanglement process is performed by two or more interlace nozzles installed between the rolls, the individual interlace nozzles interfere with each other and give entanglement having high entanglement strength. It was difficult. In other words, if the rotation of the yarn that occurs when the entanglement is applied is generated by two interlace nozzles installed between the rolls, the rotation to the respective yarns will cancel each other out. The convergence of the yarn was lowered. Therefore, it has been difficult to provide sufficient confounding performance.

Those who produce the raw yarn used for the warp of the seat belt are forced to adopt intermediate processing conditions to avoid both the above-mentioned problems caused by excessive entanglement and problems caused by missing entanglement. However, when entanglement processing is performed using a conventional entanglement imparting nozzle, if the processing conditions are tightened in an attempt to completely avoid entanglement loss, strength reduction or glare occurs, and strength reduction or glare is completely eliminated. If you try to avoid the process conditions and make it easier, it is a fact that entanglement is lost due to the tension applied in the webbing manufacturing process for seat belts, and there is no reduction in strength, no glare, and there is no entanglement missing. The current situation was not.
Japanese Patent Laid-Open No. 03-40829 (Claims) Special table 2003-521589 specification (Claims) JP-A-60-110916 (Claims)

  The present invention has been achieved as a result of studying the solution of the problems in the conventional technology described above as a problem, and has high strength, little change in entanglement before and after being woven at a high density in a needle loom, and the strength of the yarn. An object of the present invention is to provide a polyester fiber for seat belts having excellent retention and process passability and good entanglement characteristics.

  In solving the above-mentioned problems, the present inventors have conducted intensive studies on the various indexes of confounding and the effect on the passability of the weaving process and the strength retention of the raw yarn. It has been found that only when the relationship is satisfied, the yarn can be a yarn having both the strength retention of the yarn and the processability during weaving as a seat belt.

According to the present invention, a polyester fiber having a fineness of 1000 to 2000 dtex and a single yarn fineness of 5 to 20 dtex, the tension length of the polyester fiber is set to L1 (cm), and tension treatment is applied with a tension of 2 cN / dtex. Provided is a polyester fiber for seat belts that satisfies the following relationship when the tear length is L2 (cm).
ΔL = | L1n−L2n | ≦ 15 (cm)
Δσ = | σ1-σ2 | ≦ 15

In the polyester fiber for seat belts of the present invention,
The strength of the polyester fiber for seat belt is 6 to 12 cN / dtex, the elongation is 10 to 20%, and the dry yield is 5 to 15%.
It is preferable that the polyester fiber for seat belt is not twisted and L1 is 5 to 80 cm.

  After converging the polyester fiber in the stretching step, it is mentioned as a preferred method for producing the polyester fiber for the seat belt that confounding is provided in the winding step.

  According to the present invention, a polyester fiber for seat belts having high strength, small entanglement change before and after being woven at a high density in a needle loom, and excellent entanglement characteristics with excellent strength retention and process passability of the yarn is obtained. be able to.

  The present invention will be specifically described below.

  The polyester fiber for seat belts referred to in the present invention is preferably an aromatic polyester composed of polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, etc., and these polyesters are within a range that does not impair the object and effect of the present invention. For example, the third component may be copolymerized, and examples of the copolymer component include aromatic dicarboxylic acids such as isophthalic acid and naphthalenedicarboxylic acid, aliphatics such as adipic acid, sebacic acid, and azelaic acid. Examples thereof include, but are not limited to, dicarboxylic acids, diethylene glycol, diol compounds such as 1,4-butanediol, and 5-sulfoisophthalic acid metal salts. However, polyethylene terephthalate is preferable from the viewpoint of excellent initial modulus and terminal modulus as a fiber.

  The fineness of the seat belt polyester fiber in the present invention is 1000 to 2000 dtex, and preferably 1100 to 1900 dtex. If the fineness is less than 1000 dtex, the strength required to protect the occupant cannot be obtained when the webbing is used. Conversely, if the fineness exceeds 2000 dtex, the thickness of the webbing becomes excessive and the retractor is stored in the retractor. May be inferior.

  The single yarn fineness of the polyester fiber for seat belts in the present invention is 5 to 20 dtex, and preferably 7 to 18 dtex. When the single yarn fineness is less than 5 dtex, the yarn-making property is deteriorated and the webbing rigidity is not obtained. On the other hand, when it exceeds 20 dtex, the single yarn stiffness is too high, and the driving property during weaving is deteriorated. In any case, the single yarn protruding from the end surface of the ear part of the webbing directly touches the occupant's skin when wearing the seat belt and gives discomfort.

  The polyester fiber for seat belts according to the present invention has a tear length of L1 (cm), and the polyester fiber is 2 cN / dtex which substantially corresponds to the tension applied to the warp and the weft when weaving at high speed with a needle loom, for example, 1900 rpm. Assuming that the tear length after tension treatment with L2 (cm) is L2 (cm), the average value when L1 is measured 50 times is L1n (cm), and the average value when L2 is measured 50 times is L2n (cm) When the standard deviation of the variation of L1 is σ1 and the standard deviation of the variation of L2 is σ2, the relationship of ΔL = | L1n−L2n | ≦ 15 (cm) and Δσ = | σ1−σ2 | ≦ 15 is satisfied. By doing so, it is possible to obtain a polyester fiber for seat belts having excellent entanglement characteristics with excellent strength retention of the yarn and processability.

  A technical feature that should be noted in the present invention is that the polyester fiber for seat belts in the present invention imparts low entanglement and high convergence in the relaxation process, and then imparts entanglement immediately before the winding process, so that single yarn For the first time, the above-described good entanglement characteristics are exhibited without generating cuts and fluff. In the drawing process, by giving the pressure of high-pressure air ejected from the entanglement nozzle to the extent that the yarn is not entangled and the convergence is improved, the occurrence of single yarn breakage and fluff can be suppressed, and good It becomes possible to obtain the polyester fiber for seat belts of the present invention to which the proper entanglement characteristic is imparted. In the drawing process, if the pressure of the high-pressure air ejected from the entanglement nozzle is set to be equal to the pressure of the high-pressure air ejected from the entanglement nozzle in the winding process, the yarn is overcooled in the drawing process, and the yarn fluff frequently occurs. However, since the confounding of the raw yarn is remarkably improved due to excessive entanglement, the degree of freedom of the original yarn decreases when confounding is applied in the winding process. It is difficult to impart a high entanglement to a thick fine filament, which is not preferable.

  In the present invention, the polyester fiber for seat belt has a strength of 6 to 12 cN / dtex, an elongation of 10 to 20%, and a dry yield of 5 to 15%, a strength of 8 to 12 cN / dtex and an elongation of 10. More preferably, it is ˜17% and dry yield is 7 to 12%. When the strength is in the range of 6 to 12 cN / dtex and the elongation is in the range of 10 to 20%, the required performance such as tensile strength and energy absorption amount as webbing is sufficient. Moreover, when the dry yield is 5 to 15%, the thermal dimensional stability of the webbing in the heat setting process during weaving is improved, and an appropriate webbing quality can be obtained. That is, it is suitable as a polyester fiber for seat belts having the above physical properties.

  Next, it is preferable that the polyester fiber for seat belts in this invention is not twisted, and it is preferable that it is 5-80 cm as a range of L1, More preferably, it is 5-60 cm, More preferably, it is 5-40 cm. In general, in order to improve the process passage stability in the weaving process, a method such as drawing twisting is adopted in the yarn forming process, and the raw yarn is twisted, but this method certainly improves the process passage stability, This is not preferable because it increases the cost and lowers the bending rigidity of the webbing. However, in the polyester fiber for seat belts of the present invention, the change in confounding before and after being woven at a high density in the needle loom is small, so there is no need for twisting, so the cost is reduced and high webbing bending rigidity is obtained. It is done. Furthermore, it is preferable that L1 is in the range of 5 to 80 cm because the weaving property of the weft does not deteriorate even under disadvantageous conditions such as using untwisted polyester fibers during weaving.

  The polyester fiber for seat belts of the present invention may contain an organic or inorganic pigment, and a black pigment is particularly preferable. It is possible to obtain polyester fibers for seat belts that have a low impact on the environment, such as by eliminating the need for dyeing by producing polyester fibers for seat belts without the need for dyeing, and at the same time, no waste dye liquid is generated. Become. Preferred pigments include zinc white, titanium oxide, bengara, titanium yellow, zinc-iron brown, titanium-cobalt green, cobalt green, cobalt blue, copper-iron black, ultramarine, calcium carbonate, manganese violet, carbon black. , Aluminum powder, bronze powder, titanium coated mica, iron oxide black, spinel black, manganese block, cobalt black and other inorganic pigments, and copper phthalocyanine blue, copper phthalocyanine green, brominated copper phthalocyanine green, dianthraquinone red, berylene Organic pigments such as scarlet, beryllen red, beryllen maroon, dioxane violet, isoindolinone yellow, metal complex salt azomethine. Among these, black pigments such as carbon black, iron oxide black, spinel black, manganese block, and cobalt black are preferable, and carbon black is particularly preferable.

  In addition, the polyester fiber for seat belts in the present invention is within a range that does not impair the objects and effects of the present invention, particles such as dulling agents, stabilizers such as antioxidants, light stabilizers, ultraviolet absorbers, electric resistance. You may contain additives, such as an inhibitor, a filler, and a crosslinking agent.

  Hereinafter, a method for producing a polyester fiber for seat belt according to the present invention will be described in detail with reference to FIG.

  The polyester fiber can be obtained by a method in which a polyester chip filled in the hopper (1) in a nitrogen atmosphere is melt-kneaded by the extruder (2), introduced into the spinning pack (3), and discharged from the base (4). it can. When the above-mentioned pigment is added, a method of preparing a polyester master chip containing a high concentration of the pigment in advance and blending the chip before melting can be employed. At this time, in order to prevent deterioration of the polymer due to heat, the residence time in the spinning machine is preferably as short as possible, and usually within 10 minutes. In order to finely disperse the pigment, it is preferable to use a twin-screw extruder type extruder or a static mixer during spinning. The spinning temperature is usually 260 to 300 ° C.

  Next, it is preferable to dispose a heating cylinder and / or a heat insulating cylinder (5) immediately below the base, and let the discharged yarn pass through the heating cylinder and / or the heat insulating cylinder (5). This heating cylinder is generally a length of 5 to 100 cm and may be any heating cylinder whose temperature is controlled at 150 to 350 ° C. The length and temperature conditions are optimal depending on the fineness of the yarn obtained and the number of filaments. It only has to be made. By using the heating cylinder and / or the heat insulating cylinder (5), the solidification of the molten polymer can be delayed and the strength of the fiber can be increased.

  The yarn that has passed through the heating tube and / or the heat insulating tube (5) is then cooled and solidified by blowing air at 10 to 100 ° C., preferably 15 to 75 ° C. in the cooling device (6). When the cooling air is less than 10 ° C., a large cooling device is required separately from the normal device, which is not preferable. In addition, when the cooling air exceeds 100 ° C., the single fiber sway during spinning becomes large, so that the single fibers collide with each other, making it difficult to produce the fibers with good spinning properties. The cooling device may be a side blowing type or an annular type blowing type. Moreover, when a high cooling effect is required like a monofilament, a cooling method such as water cooling can be adopted.

  The unstretched yarn that has been cooled and solidified is then applied with an oil agent by an oil supply device (7). The oil agent may be aqueous or non-aqueous, but contains a smoothing agent as a main component, includes a surfactant, an antistatic agent, an extreme pressure agent component, etc., and excludes an active component in the polyester resin. A composition is preferred.

  The unstretched yarn provided with the oil is wound around the first take-up roller (1FR) (8) and taken up. The surface speed of 1FR, that is, the take-up speed is preferably 300 m / min or more, more preferably 500 m / min or more. Polyester fibers can be obtained even at a take-off speed of less than 300 m / min, but are difficult to employ because of low production efficiency. Although there is no particular upper limit to the take-up speed, the take-up speed is preferably 5000 m / min or less, more preferably 3000 m / min or less in the case of industrially stable production. The drawing may be carried out by using ordinary heat drawing, and the draw ratio can be changed depending on the birefringence of the undrawn yarn, the drawing temperature, the drawing ratio distribution at the time of multi-stage drawing, and the like. 0 times is preferable and 3.5 to 6.0 times is more preferable.

  The undrawn yarn taken up at the take-up speed is drawn once or continuously without being taken up. Similar to 1FR, a Nelson type roller having two rollers as one unit is a second take-up roller (2FR) (9), a first drawing roller (1DR) (11), a second drawing roller (2DR) ( 12) and the relaxation roller (RR) (13) are arranged side by side, and the yarn is sequentially wound to perform a drawing heat treatment. Usually, stretching is performed between 1FR and 2FR to converge the yarn. A preferable stretch ratio is 0.5 to 7%, more preferably 1 to 5%. 1FR is heated to 50 to 80 ° C., preferably 60 to 70 ° C., and the take-up yarn is preheated and sent to the next drawing step.

  The first stage stretching is performed between 2FR and 1DR, and the 2FR temperature is 80 to 120 ° C, preferably 90 to 110 ° C, and the 1DR temperature is 90 to 140 ° C, preferably 100 to 130 ° C. Is set to a range of 30 to 90%, preferably 50 to 90% of the overall draw ratio.

  The second stage stretching is performed between 1DR and 2DR, and 2DR is 160 to 240 ° C, preferably 180 to 220 ° C. The yarn that has been subjected to the two-stage drawing is subjected to a relaxation treatment of 0 to 7%, preferably 0 to 5%, more preferably 0.5 to 3% with respect to the RR, and only the strain caused by the hot drawing is removed. In addition, the highly oriented structure achieved by stretching can be fixed, or the orientation of the amorphous region can be relaxed to reduce the thermal shrinkage rate. RR uses a non-heated roller or a roller heated to 160 ° C. or less.

  For example, an entanglement processing device (10) is installed between 2FR and 1DR. The air pressure of the entanglement processing apparatus is set in the range of 0.2 to 0.5 MPa, preferably 0.3 to 0.4 MPa.

  Further, the relaxed yarn passes through the entanglement processing device (14) and is wound up by the winder (15). At this time, the air pressure of the entanglement processing apparatus is set to a range of 0.6 to 0.9 MPa, preferably 0.7 to 0.8 MPa.

  Thus, a polyester fiber for a seat belt having high strength, low entanglement change before and after being woven at a high density in a needle loom and excellent entanglement characteristics with excellent strength retention and processability of the original yarn is obtained. be able to.

  Hereinafter, embodiments of the present invention will be described in more detail by way of examples. The definition and measurement method of the characteristics used in the specification text and examples are as follows.

(1) Fineness JIS L1013 8.3.1 Positive fineness a) Measured according to the method A at 5 mN / tex × display tex number as a predetermined load and 90 m as a predetermined yarn length.

(2) Single yarn fineness A value obtained by dividing the fineness measured in (1) by the number of single fibers constituting the polyester fiber was adopted.

(3) Strength / Elongation The sample was measured with a “TENSILON” UCT-100 manufactured by Orientec Co., Ltd. under the constant speed elongation conditions shown in the JIS L1013 8.5.1 standard time test. At this time, the holding interval was 25 cm, the tensile speed was 30 cm / min, and the number of tests was 10 times. The elongation at break was determined from the elongation at the point showing the maximum strength in the SS curve.

(4) Dry heat shrinkage JIS L1013 (1999) 8.18.2a) according Method A, 5 mN / tex × displayed tex number as a predetermined load ^(29), 40 times the predetermined load ⁽²⁹⁾ as a predetermined load ⁽³⁰⁾ The load was measured at 150 ° C. as an appropriate temperature ⁽³¹⁾ .

(5) Intrinsic viscosity The relative viscosity η of a solution in which 8 g of a sample was dissolved in 100 ml of orthochlorophenol was measured using an Ostwald viscometer (25 ° C.), and calculated by the following approximate equation.
Intrinsic viscosity = 0.0242η + 0.2634

(6) Tear Length The center of the yarn was torn with a finger, the length was measured 50 times, and the average value was L1n. Further, between two pairs of rolls with different speeds, a tension of 2 cN / dtex was applied to the yarn and the yarn was run at a speed of 100 m / min, and then wound up once, and the tear length described above for this yarn was measured 50 times. The average value was defined as L2n.

(7) Stability through process during weaving Evaluation was made based on the frequency of stopping during weaving due to defects related to the convergence of warp and weft.

[Example 1]
A polyethylene terephthalate polymer having an intrinsic viscosity of 1.38 obtained by solid phase polymerization was continuously fed to a 290 ° C. single screw extruder and continuously melted.

  The melted polymer is kneaded with an eight-stage static mixer through a pipe at 290 ° C, weighed with a gear pump so that the total fineness becomes 1670 dtex, then guided to a spin pack at 290 ° C, and passes through a 20 micron cut filter in the pack. Then, extrusion spinning was performed from a die having 140 round single holes having a hole diameter of 0.5 mm and a hole length of 1.1 mm.

  After passing through a heating cylinder having a length of 50 cm and an atmospheric temperature of 300 ° C. provided with the spun yarn under the base, 50 ° C. cold air was blown at a rate of 40 m / min using a uniflow-type chimney and solidified. An oil agent (manufactured by Sanyo Chemical Co., Ltd .: Sun Oil F) was applied with an oil agent roll. The yarn provided with the oil agent was wound up at 1 FR (70 ° C.) having a surface speed of 475 m / min, and then subjected to the stretching step continuously.

  2FR (100 ° C.) at a speed of 500 m / min, 1DR (110 ° C.) at a speed of 1800 m / min, 2DR (210 ° C.) at a speed of 2900 m / min, RR at a speed of 2850 m / min (non-heated) The film was stretched by being continuously subjected to the above. The entanglement processing device is installed between 2FR and 1DR (AL-11 manufactured by Toray Industries, Inc.) and between RR and the take-up roller (PolyJet-TG manufactured by Heberline Co., Ltd.). The polyester fiber for seat belts was obtained by spraying. Table 1 shows the characteristics of the obtained polyester fiber for seat belts.

  The obtained polyester fibers for seat belts are 300 warp yarns. As weft yarns, two polyethylene terephthalate fibers (700 dtex / 72 filaments) having a strength of 6.5 cN / dtex and an elongation of 20% are aligned. Weaving was performed at a rotational speed of 1900 rpm, and the process passing stability during weaving was evaluated. The evaluation results are shown in Table 1.

[Example 2]
Contains polyethylene terephthalate polymer having an intrinsic viscosity of 1.38 obtained by solid phase polymerization and 20% by weight of carbon black pigment (Dainippon Ink Industries, Ltd., channel black particle size distribution 3 to 20 mm) based on 100% by weight. The polyethylene terephthalate master polymer having an intrinsic viscosity of 1.1 is continuously fed into a twin screw extruder type extruder at 290 ° C. at a ratio of 40: 1 while continuously metered with a measuring instrument, and continuously melted. Except that, the same procedure as in Example 1 was performed. The evaluation results are shown in Table 1.

[Example 3]
Other than setting the pressure of the high pressure air of the entanglement processing device installed between 2FR and 1DR to 0.2 MPa and the pressure of the high pressure air of the entanglement processing device installed between RR and the winding roller to 0.6 MPa Was carried out in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Example 4]
The pressure of the high-pressure air of the confounding processing device installed between 2FR and 1DR was set to 0.2 MPa, and a PS-1600 parallel jet (made by Heberline) was used as the confounding processing device between RR and the winding roller. The same procedure as in Example 1 was performed except that it was used. The evaluation results are shown in Table 1.

[Example 5]
Except that the confounding apparatus is installed between 1DR and 2DR, and that the high-pressure air pressure of the confounding apparatus installed between 1DR and 2DR is set to 0.2 MPa, the same procedure as in Example 1 is performed. It was. The evaluation results are shown in Table 1.

[Comparative Example 1]
This was performed in the same manner as in Example 1 except that the pressure of the high-pressure air of the confounding apparatus installed between 2FR and 1DR was set to 0.1 MPa. The evaluation results are shown in Table 2.

[Comparative Example 2]
Except that the pressure of the high-pressure air of the confounding processing device installed between 2FR and 1DR was set to 0.1 MPa, and that a PS-1600 parallel jet was used as the confounding processing device between RR and the winding roller The same procedure as in Example 1 was performed. The evaluation results are shown in Table 2.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that the confounding processing device installed between 2FR and 1DR was not used and that a PS-1600 parallel jet was used as the confounding processing device between RR and the winding roller. . The evaluation results are shown in Table 2.

[Comparative Example 4]
Other than setting the pressure of the high pressure air of the entanglement processing device installed between 2FR and 1DR to 0.7 MPa, and the pressure of the high pressure air of the entanglement processing device installed between RR and the winding roller to 0.7 MPa Was carried out in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 5]
The same procedure as in Example 1 was performed except that two entanglement processing apparatuses were installed between 2FR and 1DR, and the pressure of the high-pressure air of each entanglement processing apparatus was set to 0.3 MPa. The evaluation results are shown in Table 2.

  As is clear from the results of Table 1, the polyester fibers for seat belts of Examples 1 to 5 that satisfy the conditions of the present invention are high in strength and have little entanglement change before and after being woven at a high density in a needle loom, and It is a polyester fiber for seat belts which has excellent entanglement characteristics with excellent strength retention of raw yarn and process passability.

  However, as shown in Comparative Examples 1 to 5 in Table 2, if the specified value of ΔL = | L1n−L2n | ≦ 15 (cm) Δσ = | σ1−σ2 | ≦ 15 of the present invention is not satisfied, The passage was remarkably deteriorated.

  The polyester fiber for seat belts of the present invention has high strength, small entanglement change before and after being woven at a high density in a needle loom, and excellent entanglement characteristics with excellent strength retention and process passability of the yarn. Therefore, it can be effectively used as a seat belt.

It is a manufacturing process flowchart of the polyester fiber for seatbelts of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hopper 2 Extruder 3 Spin pack 4 Base 5 Heating cylinder and / or heat insulation cylinder 6 Cooling device 7 Oil supply device 8 First take-up roller (1FR)
9 Second take-up roller (2FR)
10 Entanglement Processing Device 11 First Stretching Roller (1DR)
12 Second stretching roller (2DR)
13 Relaxing roller (RR)
14 Confounding processing device 15 Winder

Claims (1)

When winding the polyester fiber after drawing, it is entangled between the take-up roller and the drawing roller to converge the fiber, and then the drawn yarn is entangled immediately before the take-up roller to give entanglement. And the manufacturing method of the polyester fiber for seatbelts which satisfies the following relationship.
ΔL = | L1n−L2n | ≦ 15 (cm)
L1n: Average value (cm) when L1 is measured 50 times
L2n: Average value when L2 is measured 50 times (cm)

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