JPH03167312A - Polyester yarn for impact absorbing air bag - Google Patents

Abstract

PURPOSE:To obtain the title yarn equal to nylon 66, having specific viscosity, density, strength, elongation, etc., showing excellent flame retardance, impact- resistant characteristics, durability, wet heat deterioration resistance and light resistance, comprising ethylene terephthalate as a main repeating unit. CONSTITUTION:The objective yarn which comprises a polyester having a repeating unit composed of >=85%, preferably >=93% ethylene terephthalate and in which the polyester has >=0.76, preferably >=0.86 intrinsic viscosity, >=1.380g/cm<3>, preferably 1.385-1,420g/cm<3> density, >=6.5g/d strength, >=14% elongation, >=120, preferably >=140 toughness, >=4.1g/d, preferably >=4.5g/d knot strength and <=10%, preferably <=5.0% dry heat shrinkage percentage. The yarn contains preferably 0.3-1.5wt.% calculated as amount of phosphorus element of bifunctional phosphorus compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to polyester fibers for impact-absorbing airbags to ensure safety. More specifically, the present invention relates to a shock-absorbing airbag that is flame retardant, has IIi impact resistance, and is durable. [Prior Art] In recent years, seat belts have been commonly used to protect occupants of various types of transportation, but even safer airbag systems are beginning to be put into practical use. Normally, airbags are made by weaving yarn and then layering rubber, which is then folded and stored.When the bag receives a shock such as an accident, it instantly inflates using high-pressure gas, ensuring the safety of the occupants. However, the important characteristics of an airbag include impact resistance that can withstand instantaneous tension, durability during long-term storage, high resistance to high-pressure gas permeability, flame retardancy, and compact size. For example, it can be stored. For example, the fibers currently used in airbags are nylon-
66, and the reality is that polyester fibers are not used; beaten polyester fibers had problems with impact resistance and could not be used. On the other hand, as a method of laminating the surface layer of the base fabric, for example, JP-A-49
A method of laminating rubber elastomer and urethane resin has been proposed in Japanese Utility Model Publication No. 47692 and Japanese Utility Model Application Publication No. 49-24-108. Further, as a method for making fibers or base fabrics flame retardant, Japanese Patent Publication No. 1982-4 1610 and Japanese Patent Publication No. 5
Publication No. 3-44599 has been proposed. Furthermore, with conventional polyester fibers, the flatness and uniformity of knitted fabrics were insufficient, making it impossible to obtain airbags with satisfactory mechanical properties. [Problem U to be solved by the invention] The above-mentioned Japanese Patent Application Laid-Open No. 64-41438 and Japanese Patent Application Laid-open No. 64-1989
-Nylon 6 proposed by the method of Publication No. 41439
6 fibers have excellent toughness and knot strength,
V resistance is an important characteristic of airbags! We were able to obtain something that satisfied the impact characteristics. In this respect, conventional polyester fibers are inferior in terms of toughness and knot strength.
When made into airbags, it had poor impact resistance and was not used as airbag fiber. On the other hand, nylon 6
6 fibers were inferior in terms of heat and humidity resistance and light resistance, and were inferior in terms of airbag durability. Japanese Unexamined Patent Publication No. 49-47692, Utility Model Application No. 49-24 1
Although the laminate described in Publication No. 08 does have flame retardancy, it does not make the base fabric flame retardant. On the other hand, Japanese Patent Publication No. 55-41610 proposes a method of adding a flame retardant substance during the production of volima, and Japanese Patent Publication No. 53-44599 proposes a method of making it flame retardant through post-processing. It was difficult to obtain satisfactory flame retardancy, and the durability of flame retardancy was also poor. In order to satisfy B flammability, it is necessary to use a large amount of flame retardant, which has the disadvantage of making the base fabric stiff and making it difficult to store in airbags that are used when folded. The present invention aims to provide a polyester fiber for impact-absorbing airbags that can provide an airbag with excellent impact resistance, flame retardancy, and durability by solving the problems of polyester. be. Furthermore, it is an object of the present invention to provide polyester fibers for use in fIs-absorbing airbags that have flatness and uniformity that have not been achieved with conventional techniques. [Means and effects for solving the problem] (1) The polyester fiber for 11 impact-absorbing airbags is polyester in which 85% or more of the repeating units are ethylene phthalate, has a density of 1.380 g/cm2 or more, and has a strength of is 6.5 gd or more, elongation is 14% or more, and toughness is 12
0 or more, knot strength is 4.1 g/d or more, dry heat shrinkage rate is 1
0% or less polyester fiber for fII impact-absorbing air bags. <<2> The polyester fiber for impact-absorbing airbags according to <<1>> above, characterized in that the fiber contains a bifunctional phosphorus compound in an amount of 0.3 to 1.5% by weight as an elemental amount of phosphorus. Shock-absorbing airbag. The present invention will be explained in detail below. In the polyester fiber for a Wi impact-absorbing airbag according to the present invention, it is essential that 85% or more of the repeating units of the polyester are ethylene terephthalate, preferably 9
0% or more, more preferably 93% or more. Furthermore, conventionally known acids and glycol components may be copolymerized within the range that does not impair the constituent elements and objects of the present invention. Examples of the copolymerized acid component include isophthalic acid, 5-sodium sulfoisophthalic acid, and adivic acid. In addition, examples of the glycol component include tetramethylene glycol, diethylene glycol, neobentyl glycol, 1.4 cyclohexanedimethanol, polyethylene glycol, and the like. By setting the intrinsic viscosity of the polyester fiber according to the present invention to 0.76 or more, the strength and durability of the airbag are improved. Shock absorption when the bag is momentarily inflated can be greatly increased. The intrinsic viscosity is preferably 0.83 or more, more preferably 0.86 or more. By making the polyester fiber for fill-absorbing airbags according to the present invention have a strength of 6.5 g/d or more, an elongation of 14% or more, and a toughness obtained by the product of strength and elongation of 120 or more, instantaneous It can withstand severe airbag inflation, and can also absorb the high energy of an ffiI strike. The toughness is preferably 130 or more, more preferably 140 or more. By setting the density of the polyester fiber for impact-absorbing airbags according to the present invention to 1.380 g/cm2 or more, the dimensional stability of the base fabric for airbags can be improved, preferably at 1.385 g/cm2 or more. a. However, considering productivity and manufacturing costs, the density is 1.420g/cm2
The following is preferable. Since the polyester fiber for fI impact-absorbing airbags according to the present invention is usually used as a MS product, the knot strength of the polyester fiber should be 4.1 g/d or more, and the dry heat shrinkage rate should be 1O% or less. This can improve the tear strength, flatness, and uniformity of knitted fabrics. The knot strength is preferably 4.3 g/d or more, more preferably 4.5 g/d or more. The dry heat shrinkage rate is preferably 7.0% or less, more preferably 5.0% or less.
The dry heat yield rate is high, especially when it exceeds 10%, 1lAIIa
! ! ! Since the flatness and uniformity of 1 cannot be maintained, not only will the shock absorption properties deteriorate, but if rubber etc. are laminated in post-processing, the adhesion will be poor, resulting in the silk fabric and rubber layer peeling off when stored for a long period of time. This results in the problem of reduced impact resistance. Furthermore, if the flatness and uniformity are poor, there is a problem in that the foldability becomes poor, the airbag becomes bulky, and the storage volume increases. A feature of the polyester fiber according to the present invention is that it contains a difunctional phosphorus compound. 0 as the amount of phosphorus element.
By containing 3 to 1.5% by weight, the flame retardance of the airbag can be improved. Preferably 0.4~
It is 1.3% by weight, more preferably 0.6 to 1.1% by weight. If the amount of phosphorus element is less than 0.31% by weight, the flame retardance of the airbag fiber will be insufficient, and if the amount of phosphorus element is more than 1.6% by weight, the strength of the polyester fiber will decrease,
In addition, since the shrinkage characteristics increase, problems arise in that flatness and dimensional stability deteriorate. The phosphorus compound of the present invention is a bifunctional phosphorus compound, and is a phosphorus compound having two ester-type related functional groups. Specific examples include phosphonates represented by the following formula (1), phosphonates represented by the formula (2>), and phosphine oxides represented by the formula (3). , R5 are the same or different groups and represent a hydrocarbon group having 1 to 18 carbon atoms, R2, R3
are the same or different groups, each having 1 to 1 carbon atoms.
18 hydrocarbon groups or hydrogen filaments, A represents a divalent organic residue, 1 A represents a trivalent organic residue, R4 represents a carboxyl group or its ester, and R6 represents a carboxyl group or an ester thereof. their esters or each other -C-C-O-
Represents a divalent ester-forming functional group that forms a 1111 0 0 ring with A2 via the group represented by. formula(
Preferred specific examples of the phosphorus compound shown in 1) include:
Examples include dimethyl phenylphosphonate and diphenyl phenylphosphonate. Preferred specific examples of the phosphorus compound of formula (2) include (2-carboxylethyl)methylphosphinic acid, (2-carboxylethyl)phenylphosphinic acid, <2-methoxycarboxylethyl>methyl phenylphosphinate, <<4-Methoxyluponylphenyl>> Examples include methyl phenylphosphinate and ethylene glycol ester of (2-(β-hydroxyethoxycarbonyl)ethyl)methylphosphinic acid. Preferred specific examples of the phosphorus compound of formula (3) include (1.
2-dicarboxyethylphosphine oxide (2.3-
dicarboxy 1 lovir) dimethylphosphine oxide,
(2.3-dimethoxyruponylethyl)dimethylphosphine oxide, (1,2-di(β-hydroxyethoxyrubonyl)dimethylphosphine oxide, etc.) Among these compounds, the phosphorus compound of formula (2) is particularly preferred. It is preferred because it has good copolymerization reactivity with polyester and is less likely to break during the polycondensation reaction. The polyester of the present invention may contain a matting agent and an ultraviolet absorber for improving light resistance in an amount not exceeding 3% by weight. [Example] The measurement method used in the example is as follows. Intrinsic viscosity:
This is the solution viscosity measured at 25°C using orthochlorophenol as a solvent. Density: Density gradient tube (2
This is the value measured at 5℃). Base fabric strength: JIS-L-1
This is a value measured using the 096A method. Phosphorus element content: This is the value measured according to "Instrumental Polymer Analysis (1) Regarding Quantification of Phosphorus During Polymer Polymerization" published by Hirokawa Shoten in 1961. Bursting strength: JIS-L-1018A method (Mullen method)
This is the value measured according to the following. Flame retardancy: Value measured according to JIS 1091 (D). Flatness: The base fabric was placed on a flat plate and judged visually. Examples 1 to 3, Comparative Examples 1 to 3 The invention will be explained in detail by referring to Examples below. To the condensate obtained by directly esterifying terephthalic acid and ethylene glycol, [2-(βhydroxyethoxycarbonyl)ethyl]methylphosphinic acid was added in the amount shown in the table as a phosphorus compound, and 0.03 part of trioxide was added. Add antimony and add 0
．． Add 1 part of titanium dioxide and heat from 250°C to 2°C in 30 minutes.
The temperature of the reaction system was raised to 85°C and the pressure of the reaction system was reduced to 0.5 mmHg. Thereafter, the reaction was carried out by maintaining this temperature and reduced pressure until the intrinsic viscosity reached 0.8.
Solid phase polymerization was carried out at 00°C under 0.4 mmHg for 18 hours.
A polyester chip with an intrinsic viscosity of 1.10 was obtained. Said,
The polymer chips after solid phase polymerization are extruded through a circular discharge hole and melt-spun at 300 to 330°C, followed by spinning at 205°C.
After stretching heat treatment at 5.6~6.0f at a temperature of 1
A filament yarn consisting of 750 denier-96 filaments was obtained by winding after relaxing treatment with a relaxation rate of ~5%. Using the obtained filament yarn, a plain woven fabric with a warp and weft density of 26 threads/inch was obtained. In Example 2, a plain woven fabric was obtained in the same manner as in Example 1, except that the phosphorus compound was changed to 1.5% by weight at the stage of obtaining the volima. In Comparative Example 1, a plain woven fabric was obtained in the same manner as in Example 1 except that the phosphorus compound was 0.2% by weight.

In Comparative Example 2, a plain woven fabric was obtained in the same manner except that the phosphorus compound was 1.7% by weight. In Comparative Example 3, a plain woven fabric was obtained in the same manner as in Example 1 except that 0.5% by weight of diphenyl phenylphosphinate was used instead of the phosphorus compound. The results are listed in the table. The polyester III4 fiber obtained in Example 1 has excellent properties such as intrinsic viscosity, density, strength, elongation, toughness, knot strength, and dry heat shrinkage rate, and the fiber can be used to weave an airbag. As a result, we obtained an excellent impact-absorbing airbag that satisfies all aspects including strength, bursting strength, flatness, and flame retardancy. In Example 2, by setting the amount of phosphorus element to 1.5% by weight, the intrinsic viscosity, density, strength,
As a result of slightly inferior properties such as elongation, toughness, and knot strength, the woven airbag had lower strength and bursting strength than Example 1. However, it was satisfactory as a shock absorbing airbag in terms of flame retardancy, flatness, etc.

In Comparative Example 1, the amount of phosphorus element was limited to 0.2% by weight, so each property of the polyester fiber and each property of the airbag were as good as in Example 1, but it was inferior in terms of flame retardancy. It was something like that.

In Comparative Example 2, each property of the polyester fiber described in Example 1 was reduced due to the phosphorus element content of 1.7% by weight, so the strength, flatness, bursting strength, etc. of the airbag were reduced. It was inferior in some respects. In Comparative Example 3, a phosphorus compound other than the one according to the present invention was used, so that the reaction did not proceed at the initial stage of obtaining the bolimar, and the desired intrinsic viscosity could not be obtained. As a result, polyester fibers have inferior intrinsic viscosity, density, strength, elongation, toughness, knot strength, and dry heat shrinkage, and airbags woven with these fibers have inferior strength, bursting strength, and flame retardancy. It became. 《Blank below〉 [Effects of the Invention] The impact-absorbing airbag of the present invention has the following excellent features. By improving toughness and knot strength, it is possible to improve impact resistance, which could not be achieved with conventional polyester M fibers, making it an airbag comparable to nylon 66, and it also has resistance to moisture and heat deterioration, light resistance, etc. I got something excellent. By improving the knot strength, it is possible to obtain a base fabric that exceeds the target strength even if the fineness of the polyester fiber is made smaller than before. Therefore, the basis weight of the base fabric could be reduced, making the airbag lighter. By making the base fabric flame retardant, even if a fire breaks out during a collision, it is possible to prevent the base fabric from burning immediately, further improving life safety. Despite improving the toughness of the yarn, we were able to significantly reduce the dry heat shrinkage rate, resulting in a base fabric with excellent flatness.

Claims (2)

[Claims] (1) The polyester fiber for impact-absorbing airbags is a polyester in which 85% or more of the repeating units are ethylene terephthalate, and the polyester has an intrinsic viscosity of 0.76 or more, a density of 1.380 g/cm^2 or more, and strength 6.5 g/d or more, elongation 14% or more, toughness 120 or more, knot strength 4.1 g/d or more, and dry heat shrinkage rate 10% or less. (2) In the polyester fiber for impact-absorbing airbags according to claim 1, the fiber contains a bifunctional phosphorus compound in an amount of 0.3 to 1.5% by weight as an elemental amount of phosphorus. Features a shock-absorbing airbag.