JPH06306729A - Base cloth for air bag - Google Patents

Abstract

PURPOSE:To obtain a base cloth for air bag having excellent mechanical properties, foldability and flatness and low air-permeability by weaving a cloth using a specific polyester fiber as the warp and the weft of the cloth. CONSTITUTION:The polyester fiber to be used in the weaving of the base cloth contains ethylene terephthalate unit accounting for >=90%, preferably >=95% of the recurring unit and has a fineness of <=280de, a single fiber fineness of >=3.6de, a tenacity of >=9.0g/d, a breaking elongation of <=15%, an intrinsic viscosity of >=0.8dl/g, a birefringence of >=0.18, a density of >=1.38g/cm<3> and a dry heat-shrinkage of <=12%. A plain weave cloth is woven by using the polyester fiber as the warp and the weft and the cloth is subjected to scouring, heatsetting and calender finishing treatment to obtain a base cloth for air bag.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing fabric made of polyester fiber for manufacturing an air bag. More specifically, the present invention relates to a shock absorbing fabric having excellent mechanical properties and folding properties and having reduced air permeability.

[0002]

2. Description of the Related Art In recent years, an airbag system has been put into practical use as a safety device for protecting passengers of various transportation facilities. Normally, an air bag is stored by weaving raw yarns, laminating and folding rubber, and in the event of a shock such as an accident, the air bag is inflated instantly by high-pressure gas to ensure the safety of passengers.

However, important characteristics as an air bag are impact resistance capable of withstanding momentary expansion, durability during long-term storage, high permeability to high-pressure gas, high flame retardancy, and compactness. It can be stored in.

For example, Japanese Patent Laid-Open No. 64-41438,
JP-A-64-41439 and JP-A-3-137
As can be seen from the known example of Japanese Patent No. 245, the fiber currently used in the air bag is nylon-66, and the polyester fiber is not used.

Nylon-66 fibers proposed by the methods of JP-A-64-41438 and JP-A-64-41439 have been obtained that satisfy the impact resistance which is an important characteristic of air bags. It was. In this respect, the conventional polyester fiber has a poor impact resistance when used as an air bag and is not used as an air bag fiber. Further, polyester fibers have greater rigidity than nylon fibers, and there is a problem in foldability when used as an air bag. On the other hand, nylon-66 fiber is inferior in wet heat resistance and light resistance, the raw material cost is higher than that of polyester fiber, and there are problems in durability and price when used as an air bag.

Japanese Unexamined Patent Publication (Kokai) No. 3-167312 discloses an air bag made of flame-retardant polyester fiber, but the strength of the polyester fiber is not sufficient and it is necessary to increase the fineness in order to satisfy the impact resistance. The polyester having such a fineness has a problem in foldability when used as an air bag.

[0007]

SUMMARY OF THE INVENTION The present invention has improved the above-mentioned problems of the prior art and uses a high-strength, low-shrinkage polyester fiber to provide an impact-absorbing air bag having excellent impact resistance and good foldability. The purpose of the present invention is to provide an uncoated polyester base fabric.

[0008]

[Means for Solving the Problems] Means for solving the above problems, that is, the constitution of the present invention comprises a polyester fiber containing ethylene terephthalate as a main component, and comprises the following (1):
It is a base fabric for an air bag, which is woven using yarns satisfying the characteristics (8) to (8). (1) Fineness ≤ 280 denier (2) Single yarn fineness ≥ 3.6 denier (3) Strength ≥ 9.0 g / d (4) Cutting elongation ≤ 15% (5) Intrinsic viscosity ≥ 0.8 dl / g ( 6) Birefringence ≧ 0.18 (7) Density ≧ 1.38 g / cm ³ (8) Dry heat shrinkage ≦ 12%

In the polyester fiber for an air bag according to the present invention, it is essential that 90% or more of the repeating unit of polyester is ethylene terephthalate, and preferably 95% or more. Further, a conventionally known acid component and glycol component may be copolymerized within a range that does not impair the constitutional requirements and objects of the present invention. Examples of the copolymerization component include isophthalic acid, 5-sodium sulfoisophthalic acid, adipic acid and the like. Examples of the glycol component include tetramethylene glycol, diethylene glycol, neopentyl glycol, 1,4 cyclohexanedimethanol and polyethylene glycol.

The denier of the polyester fiber according to the present invention must be 280 denier or less, preferably 2 denier.
It is 40 denier or less, more preferably 200 denier or less. When it exceeds 280 denier, the bulkiness when formed into an air bag becomes large, and the goal of the present invention cannot be achieved in terms of foldability.

The monofilament filament of the polyester fiber according to the present invention requires 3.6 denier or more. It is preferably 4.5 or more. If it is less than 3.6 denier, the handling property in the post-processing step such as weaving becomes poor and the process passability becomes a problem.

The strength of the polyester fiber according to the present invention is required to be 9 g / d or more. It is preferably 10 g / d or more. When it is less than 9 g / d, the mechanical properties required for an air bag are combined with the fact that the fineness of the yarn is small,
For example, the tensile strength and burst strength cannot be satisfied, and there is a risk of damage during operation of the airbag. The cutting elongation of the polyester fiber according to the present invention needs to be 15% or less. If it exceeds 15%, the fiber strength of the present invention cannot be obtained, and the target of the present invention cannot be achieved in terms of mechanical properties when formed into an air bag.

The intrinsic viscosity of the polyester fiber according to the present invention is required to be 0.8 dl / g or more. 0.8 dl / g
If it is less than 100%, the mechanical properties and durability when formed into an air bag will deteriorate, and the intrinsic viscosity, that is, the molecular weight will be combined with the yarn strength, and the impact absorption property when the air bag is momentarily inflated can be improved. Disappear.

The dry heat shrinkage of the polyester fiber according to the present invention must be 12% or less. It is preferably 10% or less. If it exceeds 12%, the flatness and uniformity of the woven fabric cannot be maintained, so that the impact absorption is lowered. Further, when the flatness and the uniformity are poor, there arises a problem that the foldability becomes poor and the air bag becomes bulky and the storage volume increases. The density of the polyester fiber according to the present invention is 1.38.
g / cm ³ or more is required. If it is less than 1.38 g / cm ³ , the target of the dry heat shrinkage of the fiber of the present invention cannot be obtained, and the target of the present invention cannot be achieved in terms of flatness and uniformity when formed into an air bag. At the time of weaving, it is desirable to use warp and weft without twisting in order to obtain low air permeability. Further, it is desirable that the cover factor (K) calculated by the following equation is 1700 or more. K = sum of warp and weft densities x (yarn denier) 1/2 (however, the density is the number of threads per inch) If K is less than 1700, sufficient low air permeability cannot be obtained.

The base fabric for an air bag of the present invention is an uncoated woven fabric, and a simple reduction in air permeability can be achieved by sanforizing or calendering. The uncoated fabric treated in this way has the required low breathability.

In the method for producing a high-strength polyester fiber according to the present invention, the spinning / drawing step, particularly the drawing step, is important. That is, for example, a birefringence of 0.002 to 0.06 obtained by melt spinning polyester having an intrinsic viscosity of 0.8 or more.
When the unstretched yarn of 0 is continuously spun or once stretched after being wound up, between the unstretched yarn first supply roller and the unstretched yarn second supply roller maintained at 100 ° C. or lower,
It is preferable to carry out a pre-drawing of 1.10 times or less, and then perform a first-stage drawing at 40% or more of the total draw ratio between the first drawing roller and the first drawing roller.
A high-temperature pressurized steam jet nozzle is provided between the stretching roller and the nozzle temperature to 200 ° C. or higher to jet high-temperature steam, and the stretching point is fixed near the high-temperature pressurized steam jet nozzle. Further, when performing the second stage stretching, the ambient temperature provided between the first stage stretching roller and the second stage stretching roller is 170 to 420 ° C.
Slit heater (a heating device provided with a slit as a yarn running path for heating while running the yarn in the slit in a non-contact state: ambient temperature refers to the temperature inside the slit) The strip is passed so that it can stay for 0.3 seconds or more, and then the strip is fed to the second stretching roller. At that time, a temperature gradient is provided in the slit heater so that the yarn inlet atmosphere temperature is 170 ° C or higher and the outlet atmosphere temperature is 420 ° C.
Below, and the yarn is 0.
It is preferable to pass the yarn so that it can stay for 3 seconds or more. In addition, after completion of the two-stage stretching, it is continuously wound without being wound once, or once wound at 230 to 165 ° C.
By performing a relaxation treatment of 0% or less, it is possible to control the dry heat shrinkage rate and density of the fiber.

[0017]

【Example】

The measuring methods used in the examples are as follows. Intrinsic viscosity: Orthochlorophenol as solvent, 25 ℃
It is the melt viscosity measured in. Birefringence: A value obtained by a retardation method using bromnaphthalene as an immersion liquid and a Berek compensator. Density: A value measured with a density gradient tube (25 ° C.) composed of n-heptane / carbon tetrachloride. Dry heat 180 ° C. Shrinkage rate: JIS L1073-1977 (6.
It is a value measured according to 12). Bursting strength: A value measured by an air bag deployment tester manufactured by Ito Seiki. Foldability: A parameter of the bulkiness when a 20 cm square fabric is folded in four. Flatness: The base cloth was placed on a flat plate and visually judged.

Example 1 A polyethylene terephthalate chip having an intrinsic viscosity (IV) of 1.1 was spun on an extruder type spinning machine and drawn to obtain a fineness of 25.
0 denier, single yarn fineness 5.5 denier, strength 10.2 g
/ D, breaking elongation of 13%, intrinsic viscosity of 0.87 dl / g, birefringence of 0.190, density of 1.399 g / cm ³ , and dry heat shrinkage of 8% were obtained. Using this thread,
A plain weave having a density of 67 wefts / inch was obtained. The woven fabric was scoured and heat set, and then calendered at a temperature of 180 ° C. under a pressure of 450 KPa to obtain a base fabric for an air bag. The characteristics of the obtained base cloth are shown in Table-
Shown in 1. An excellent airbag was obtained that satisfied all mechanical properties, foldability, low air permeability, and flatness.

Example 2 Polyethylene terephthalate chips of IV1.2 were spun by an extruder type spinning machine and drawn to have a fineness of 230 denier,
Single yarn fineness 4.0 denier, strength 11.0 g / d, breaking elongation 11%, intrinsic viscosity 1.01 dl / g, birefringence 0.1
A polyester yarn having a density of 94, a density of 1.398 g / cm ³ , and a dry heat shrinkage of 8% was obtained. Using this yarn, a plain weave having a plain weave having a density of 73 wefts / inch is obtained. This woven fabric was treated in the same manner as in Example 1 to obtain a base fabric for an air bag. The characteristics of the obtained base fabric are shown in Table 1. Mechanical properties, foldability,
Low air permeability and flatness were all satisfied, and mechanical properties were extremely good.

Example 3 Polyethylene terephthalate chips of IV1.2 were spun by an extruder type spinning machine and drawn to obtain a fineness of 180 denier.
Single yarn fineness 4.0 denier, strength 11.5 g / d, breaking elongation 10%, intrinsic viscosity 1.05 dl / g, birefringence 0.1
A polyester yarn having a density of 98, a density of 1.398 g / cm ³ and a dry heat shrinkage of 8% was obtained. Using this yarn, a plain weave having a density of 80 warps / inch was obtained. This woven fabric was treated in the same manner as in Example 1 to obtain a base fabric for an air bag. The characteristics of the obtained base fabric are shown in Table 1. Mechanical properties, foldability, low air permeability, flatness, etc. were all satisfied, and foldability was extremely good.

Comparative Example 1 A yarn having a dry heat shrinkage rate of 14% obtained according to Example 1 was processed in the same manner as in Example 1 to obtain an air bag base fabric. The characteristics of the obtained base fabric are shown in Table 1. The mechanical properties and foldability were as good as in Example 1, but they were inferior in terms of low air permeability and flatness.

Comparative Example 2 A yarn having a strength of 8.6 g / d and a breaking elongation of 17% obtained according to Example 1 was processed in the same manner as in Example 1 to obtain an air bag base fabric. The characteristics of the obtained base fabric are shown in Table 1. Foldability, low air permeability, and flatness were good as in Example 1, but poor in mechanical properties.

Comparative Example 3 A plain fabric having a density of 57 wefts / inch was woven through the yarn having a fineness of 350 denier obtained according to Example 1 to obtain an air bag base fabric in the same manner. The characteristics of the obtained base fabric are shown in Table 1. The mechanical properties, low air permeability, and flatness were good as in Example 1, but were poor in terms of foldability.

[0025]

[Table 1]

[0026]

Industrial Applicability According to the present invention, it is possible to provide an uncoated polyester woven fabric for an air bag which is inexpensive and has excellent impact resistance, low air permeability, flatness, and good foldability, and it is possible to reduce the size and weight of the storage device. Furthermore, the spread of the airbag system will be promoted, and it will be possible not only for car occupants but also for various transportation systems.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location D02J 1/22 J 301 A

Claims (1)

[Claims] 1. A base fabric for an air bag, which is made of a polyester fiber containing ethylene terephthalate as a main component, and is woven using yarns satisfying the following characteristics (1) to (8). . (1) Fineness ≤ 280 denier (2) Single yarn fineness ≥ 3.6 denier (3) Strength ≥ 9.0 g / d (4) Cutting elongation ≤ 15% (5) Intrinsic viscosity ≥ 0.8 dl / g ( 6) Birefringence ≧ 0.18 (7) Density ≧ 1.38 g / cm ³ (8) Dry heat shrinkage ≦ 12%