JPH06257062A - Webbing for seat belt - Google Patents

Abstract

PURPOSE:To produce a lightweight webbing for seat belts, excellent in strength and good in impact energy-absorbing performance. CONSTITUTION:Copolyethylene terephthate fibers having an intrinsic viscosity of >=0.7, a breakage strength of >=5g/d, a breakage elongation of 10-30%, a boiling water shrinkage of >=20%, and a dry thermal shrinkage stress of >=0.2g/d are woven using as wefts into a webbing, which is subjected to a restricted shrinkage heat treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat belt webbing. More specifically, the present invention relates to a webbing excellent in energy absorption performance, which is formed by weaving a polyester fiber having a property suitable for webbing a vehicle seat belt as a warp.

[0002]

2. Description of the Related Art Originally, the maximum required characteristic of vehicle seat belt webbing is to absorb and reduce the impact force received by an occupant during a collision, that is, energy absorption performance. Some suggestions have been made. For example, Japanese Patent Publication No. 53-1874, Japanese Patent Publication No. 53-2981, Japanese Patent Publication No. 55-11
In Japanese Patent No. 053, etc., it is proposed to combine two or more kinds of warp yarns having different tensile strength, elongation, weaving reduction ratio, etc. so as to smoothly absorb energy. However, as a result of additional examination of these methods, it was found that the energy absorption had to be stepwise in any method. That is, it is difficult to absorb energy continuously and smoothly, and the temporary sudden impact force that the occupant receives is moderated, but two or more kinds of warp yarns successively take over the impact force. There is a practical drawback that the occupant receives an uncomfortable impact force at the transfer stage. Further, in producing webbing by these methods, it is always necessary to prepare two or more kinds of polyester fibers at the same time, which is inefficient, and there is a problem in terms of management.

Fibers that can solve such problems are disclosed in Japanese Patent Laid-Open Nos. 59-179842 and 62-11257.
No. 2, JP-A 1-298209, and the like propose polyester fibers having a specific elongation curve, which have a specific range of intrinsic viscosity, birefringence, breaking strength, breaking elongation, and the like. Has been done.

However, it has been found that the polyester fibers obtained by the methods proposed by these have low breaking strength, and the breaking strength is insufficient according to the seat belt standard, which requires lightness of the webbing itself.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to have a light weight and a sufficiently large breaking strength and to continuously and smoothly absorb impact energy. To provide a webbing for a seat belt that can be used.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have used a highly shrinkable polyester fiber made of polyethylene terephthalate copolymerized with a third component for a warp, and after weaving. The webbing obtained by shrinkage heat treatment has been found to have excellent impact energy absorption characteristics and has reached the present invention.

That is, the present invention comprises a polyester fiber obtained by copolymerizing ethylene terephthalate with a third component in an amount of 5 to 20 mol% and is woven using polyester fibers satisfying the following physical properties (a) to (e) at the same time. This is a webbing for a seat belt, which is then heat-treated for limited shrinkage. (A) Intrinsic viscosity (IV) ≥ 0.7 (b) Breaking strength (ST) ≥ 5 g / de (c) Break elongation (EL) = 10 to 30% (d) Boiling water shrinkage (BWS) ≥ 20% (E) 100 ° C. dry heat shrinkage stress ≧ 0.2 g / de As the polymer constituting the polyester fiber used in the present invention, a polyester having ethylene terephthalate as a repeating unit is copolymerized with 5 to 20 mol% of the third component. It is a copolyester. As the third component to be copolymerized, for example, isophthalic acid, naphthalenedicarboxylic acid,
Examples thereof include neopentyl glycol and 2,2-bis (4- (β-hydroxyethoxy) phenyl) propane. Among them, isophthalic acid or neopentyl glycol is a webbing in which a high heat shrinkage stress and a high heat shrinkage rate are easily achieved by imparting internal strain to the fiber structure of the polyester fiber, and the impact energy absorption property is remarkably improved. It is particularly preferable because it can be obtained.

When the copolymerization ratio of the third component is less than 5 mol% with respect to the ethylene terephthalate unit, it is difficult to obtain a polyester fiber having a high shrinkage property, and the object of the present invention cannot be achieved. On the other hand, when the copolymerization ratio exceeds 20 mol%, the crystallinity of the polyester is lowered and it is difficult to obtain a high-strength fiber having a breaking strength of 5 g / de or more, which is not preferable.

Next, the intrinsic viscosity IV (measured with an orthochlorophenol solution at 30 ° C.) of the polyester fiber according to the present invention needs to be 0.7 or more. If the IV is less than 0.7, the tenacity and energy absorption characteristics required for the warp of the webbing for a seat belt cannot be obtained, which is not preferable.

The breaking strength must be 5 g / de or more, preferably 5.5 g / de or more, and if it is less than this, the breaking strength of the obtained webbing will be insufficient. Breaking elongation is 1
It is necessary to be in the range of 0 to 30%, and when it is less than 10%, even if the woven webbing is subjected to shrinkage heat treatment, 113
It becomes difficult to increase the elongation under a load of 0 kg, the energy absorption amount decreases, and the impact force that the occupant receives from the seat belt during a collision increases. On the other hand, when it exceeds 30%, it becomes difficult to maintain the breaking strength of the webbing for a seat belt at a sufficient level.

Further, in the present invention, in addition to the above-mentioned characteristics, the boiling water shrinkage ratio BWS is 20% or more, and the dry heat shrinkage stress at 100 ° C. (thermal stress at 100 ° C. in the heat stress curve) is 0.2.
The greatest feature is that polyester fibers having a high shrinkage property such as g / de or more are used for the warp. That is, with such high shrinkage characteristics (copolymerization)
When polyester fibers are subjected to shrinkage heat treatment in a particularly limited state, they can relax and stabilize internal strain without significantly changing the fiber structure, and as a result, elongation at a state where the breaking strength of the webbing is maintained. And an excellent energy absorption characteristic can be obtained.
When the boiling water shrinkage is less than 20% or the 100 ° C. dry heat shrinkage stress is less than 0.2 g / de, even if the webbing after weaving is subjected to the limited shrinkage heat treatment, a seatbelt webbing having high energy absorption properties is obtained. I can't get it.

In the present invention, the polyester fiber having the above characteristics is used as the warp yarn, and the weaving may be performed, for example, as follows. (1) Total fineness of warp 1000 to 1500 denier (2) Number of warp 320 to 400 denier / 50 mm (3) Total fineness of weft 1000 to 1500 denier (4) Number of weft 13 to 17/25 mm The obtained webbing is Although the shrinkage heat treatment is performed in the warp direction, the heat treatment may be performed alone or simultaneously with post-processing such as dyeing or resin processing. The rate of shrinkage varies depending on the target elongation of the obtained webbing and the contraction property of the polyester fiber used for the warp, but the elongation of the obtained webbing under a load of 1130 kg is 20 to
A ratio in the range of 50%, preferably a shrinkage ratio of 15 to 2
It is preferable to perform heat treatment for limiting shrinkage so as to be in the range of 5%. When the load elongation is less than 20%, the collision energy absorption characteristics tend to be insufficient, while when it exceeds 50%, collision is absorbed. There is a tendency for the occupant protection performance to deteriorate due to the stretching of the belt. Further, the relaxation heat treatment tends to result in insufficient breaking strength. The webbing for a seat belt having such a structure has a strong strength of 1500 kg or more and a belt thickness of 1.
3 mm or less, ELR (Emergency Locking Retrac
It can be installed on a 3-point seat belt.

The polyester fiber used in the warp of the seat belt webbing of the present invention described above is
For example, it can be manufactured by the following method. That is, a polyethylene terephthalate-based copolyester obtained by copolymerizing a predetermined amount of a third component having an intrinsic viscosity of 0.80 or more was melted and discharged, and the discharged yarn was passed through an atmosphere heated to a temperature equal to or higher than the melting point. Then, it is cooled and solidified with cooling air, and then an oil agent is applied in an amount of 0.05 to 1.0% by weight. The unstretched yarn obtained in this manner may be wound on an unstretched package through a take-up roller and drawn in a separate process, or may be continuously drawn after passing through the take-up roller without being wound. . The take-up speed of the undrawn yarn is preferably 1500 m / min or less in order to suppress oriented crystals in order to satisfy the strength and shrinkage properties after drawing. The stretching conditions are, for example, 75 to 9 or more, which is higher than the glass transition temperature of the third component copolyester with a heating roller.
After preheating at a temperature of 5 ° C., the first stage is drawn at a draw ratio of 2.0 to 4.0 times at a draw ratio according to the take-up speed of the undrawn yarn, and then the second stage while heating at a temperature of room temperature to 160 ° C. After stretching, it is wound up. When the yarn temperature of the second stage drawing exceeds 160 ° C, the thermal stress value at 100 ° C in the thermal stress curve is 0.2 g.
Does not exceed / de.

[0014]

The copolymerized polyester fiber used in the present invention has a thermal stress curve having a thermal stress at a temperature of 100 ° C. (100 ° C. dry heat shrinkage stress) of 0.2 g / de or more and a boiling water shrinkage of 20%. Since it has the high shrinkage characteristics as described above, it is possible to perform the shrinkage heat treatment while applying a stress during the shrinkage heat treatment, and it is possible to remove the internal strain of the fiber structure while maintaining the fiber strength. As a result, the obtained webbing for a seat belt has improved elongation without significantly lowering breaking strength and remarkably improved energy absorption characteristics.

Therefore, according to the seat belt webbing of the present invention, there is provided a seat belt which does not cause a belt breakage at the time of a collision even if the weight is reduced and has sufficient energy absorption performance for ensuring the safety of an occupant. It becomes possible to do.

[0016]

The present invention will be described in more detail with reference to the following examples. The evaluation items in the examples are as follows.

Dry heat shrinkage stress at 100 ° C. An original load of 25 cm yarn length is fixed by applying an initial load, and the shrinkage stress generated by heating from room temperature at a speed of 4 ° C./min is measured.

Energy Absorbing An initial load of 20 kg is applied to the webbing, and a point at a distance of 20 cm in the warp direction is set as a reference point, and the load is further 1
The load curve is measured by applying a load up to 130 kg, and then the weight is immediately reduced to the initial load to measure the unloading curve to obtain a load / unloading curve as shown in FIG.

The energy absorption of webbing is shown in FIG.
The area (work load) of the shaded area shown in (5) is multiplied by 5, which is a measure of energy absorption per 1 m of the belt.

The average energy of the occupant when a vehicle collides at a speed of about 60 km / hour is about 300-4.
It is 00 kgf · m, and if most of this energy is absorbed, the occupant does not collide with the steering wheel or the automobile panel, or the collision can be made to be minor. Therefore, the energy absorption is 400 kgf.
・ It is important to make it more than m.

The webbing strength was determined to be 2000 kg or more.

[0022]

Examples 1 to 6 and Comparative Examples 1 and 2 Polyethylene terephthalate obtained by copolymerizing the third component shown in Table 1 was melted at 290 ° C. and 270 from the discharge hole to 30 cm directly below the surface of the die.
After the yarn passed through the atmosphere heated to ℃ is blown with cooling air to be solidified and then an oil agent is applied, 900
It was wound at a speed of m / min. The obtained unstretched yarn was preheated at a temperature of 90 ° C and then stretched 3.5 times to the first stage, and then 40 ° C.
The second stage drawing was performed from 1.30 times to 1.60 times while heating to 160 ° C. to obtain polyester fibers of 1300 denier / 480 filaments.

The polyester fiber obtained is used as a warp yarn 3
Sixty yarns were used, and each warp was twisted at 70 T / m. On the other hand, the weft has a strength of 7.0 g / de and an elongation of 20.
% Polyester fibers (630 denier / 72 filaments) were aligned and used. Weft density is 15 threads / 2
A webbing having a width of 51 mm was woven by driving in 5 mm.
The woven fabric is dipped in a dye bath having the following formulation, and then at 250 ° C. for 1
Heat stained for minutes. At that time, a speed difference was provided between the supply roller and the take-up roller of the woven fabric so that the 20% limited shrinkage heat treatment was performed. Dianix E Blue (manufactured by Mitsubishi Kasei): 100 g / L Disper TL (manufactured by Meisei Kagaku): 1 g / L Sodium alginate: 0.5 g / L Acetic acid (for adjusting to pH 4): 0.1 ml / L Water: After washing with residual water , A polyester urethane resin aqueous dispersion Bondic 1620 (manufactured by Nippon Reichhold Co., Ltd .: 10% by weight), squeezed and heat treated at 180 ° C. for 2 minutes, and a 49 mm wide webbing for seat belts Obtained. The results are shown in Table 1.

[0024]

[Table 1]

[Brief description of drawings]

FIG. 1 is a graph showing a stretch curve of a polyester fiber used for a warp of a webbing of the present invention.

FIG. 2 is a graph showing a load / unload curve for obtaining energy absorption of webbing.

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Claims (2)

[Claims] 1. Ethylene terephthalate containing 5 parts of a third component
A webbing for a seat belt formed by weaving a polyester fiber, which is composed of a copolymerized polyester of 20 mol% to 20 mol% and satisfying the following physical properties (a) to (e) at the same time, as a warp, and then heat-shrinks the film to a limited shrinkage. (A) Intrinsic viscosity (IV) ≥ 0.7 (b) Breaking strength (ST) ≥ 5 g / de (c) Break elongation (EL) = 10 to 30% (d) Boiling water shrinkage (BWS) ≥ 20% (E) 100 ° C dry heat shrinkage stress ≧ 0.2 g / de 2. The elongation under a load of 1130 kg is 20 to 50.
%, The webbing for a seat belt according to claim 1.