JPH02227350A - Webbing for seat belt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] E-Industrial Application Field] The present invention relates to webbing for seat belts, and more specifically, the present invention relates to webbing for seat belts.
The present invention relates to webbing for seat belts that has improved properties such as abrasion resistance, modulus, durability, impact resistance, fatigue resistance, light resistance, and dyeability by using special fibers.

[Prior Art] Conventionally, thermoplastic synthetic fibers such as nylon and polyester have been used as weft and warp materials for seat belt webbing, for example, in Japanese Patent Publication No. 56-42.
It is known from Publication No. 72.

[Problem to be Solved by the Invention 1] As described in the above-mentioned Japanese Patent Publication No. 56-4272, polyester fibers are mainly used as warps for weaving seat belt webbing. In the case of the polyester I1M, although it is excellent in high strength and high elastic modulus, it has poor abrasion resistance and particularly poor shock absorption properties, so by repeatedly storing it in a retractor and taking it out from the retractor, In particular, there was a problem that the ends in the width direction were unraveled and became fluffy.

On the other hand, when nylon 1fill is used as the warp for weaving seat belt webbing, the modulus is
and had the problem of poor dimensional stability. Furthermore, when the seat belt is normally attached to the car and the car is parked under the scorching sun, especially in the summer, it is exposed to direct sunlight and radiant heat. This sometimes resulted in a decrease in strength and poor durability.

The object of the present invention is to solve the problems in the prior art described above, and to provide a material that has excellent wear resistance, shock absorption resistance, light resistance, and durability, as well as high strength, high elastic modulus, modulus, and dimensional stability. Our objective is to provide webbing for seat belts.

[Means and effects for solving the problems] The structure of the present invention is as follows: (1) In the webbing for a seat belt, the warp for weaving the webbing includes a core component mainly composed of polyamide, and a periphery of the core component. and a sheath component whose main component is polyester made of ethylene terephthalate. It is characterized by being woven using fibers that have an elasticity of 7.5 q/d or more, an elongation of 20% or less, an initial tensile resistance of 60 g/d or more -F, and a dry heat shrinkage rate of 7% or less. Webbing for seat belts.

(2) The seat belt webbing described in (1) above, which is woven using a core-sheath composite I1M made of polyamide and polyester for the warp and weft.

It is in.

The composite ill characteristics applied to the webbing for seat belts according to the present invention have not been achieved with conventional technology.
The high modulus and heat resistance close to that of polyester, and the peel durability of the polymer at the core-sheath composite interface, the specified birefringence, density, and DSCSC melting peak 1 of the polyester and polyamide core components forming the sheath and core, respectively, and the polyester This is demonstrated by the combination of high initial tensile resistance and low terminal modulus of the sheath fibers.

In order to obtain a composite fiber strength of 7.5 a/d or more, the intrinsic viscosity (η) of the polyethylene terephthalate fiber as a sheath component is 0.
．． It has a high viscosity of 7 or more, preferably 0.8 or more.

Similar to the polyester sheath component, the polyamide core component polymer also requires a high degree of polymerization in order to obtain a high-strength composite fiber, and the relative viscosity of the sulfuric acid is 2.8 or more, preferably 3.0 or more.

The ratio of the polyester sheath component of the composite AIN is 10 to 7.
It is 0ffl1%. If the polyester component is less than 10% by weight, it is not possible to effectively utilize the modulus and dimensional stability of the polyester component to form the Tsuru Composite II, and it is not possible to obtain a preferred webbing for a seat belt.

On the other hand, if the polyester sheath component accounts for 70% by weight or more, when the composite fibers are woven into a seatbelt webbing, improvements in the abrasion resistance, heat resistance, etc. of the seatbelt webbing cannot be achieved.

In the composite fiber, both the polyester sheath component and the polyamide core component are highly oriented and crystallized, and the polyester sheath component has a birefringence of 160X10' to 190X10-3.
It is desirable to keep it within the range of 160 x 10
If it is less than -3, the strength of the composite fiber may not be 7.5 g/d or more, and the initial tensile resistance may not be 60 q/d or more.

Moreover, if it exceeds 190×10 −3 , the wear resistance, dimensional stability, and fatigue resistance may not be improved.

On the other hand, the birefringence of the polyamide core component is highly oriented, such as 5g x 10'iX or more, usually 55x10'iX or more. When the birefringence is less than 5g x 10°1, the composite 8! has high strength and high initial tensile resistance! It is difficult to obtain support.

The birefringence of the core-sheath composite fiber can be measured as follows.

The sheath portion is directly measured using a transmission interference microscope, and the sheath portion is measured using a transmission interference microscope after decomposing the polyester sheath component with sodium hydroxide, potassium hydroxide, etc.

The density of the polyester sheath component is 1,395g103 or more,
The polyamide core component is 1.1400/rJ3 or more,
It is desirable that the fibers be highly crystallized, and the dimensional stability of the composite fibers will be excellent if the density is at least the specified value.

The density of the polyamide core component is determined by decomposing and removing the polyester sheath component with sodium hydroxide, potassium hydroxide, etc., and the density of the polyester component is calculated from the density of the composite my and the density of the polyamide core. You can ask for it.

The peak temperature of the DSC melting curve showing the characteristics of the crystal structure of the polyester sheath component in the composite fiber is 247 ° C.
The temperature is preferably 248° C. or higher. The higher the peak temperature is, the larger the crystals are and/or the more complete the crystals are, which corresponds to the more stable the fiber structure. The melting peak temperature of the polyester sheath component lIN is 24
If the temperature is less than 7°C, the desired modulus and dimensional stability may not be obtained.

Another feature that reflects the fiber structure of the composite fiber is the polyester sheath component! The fiber has a high initial tensile resistance of 90 q/d or more and a low terminal modulus of 20 g/d or less, and has a high initial tensile resistance. The polyester sheath component has a high terminal modulus and is characterized by less loss of strength in post-processing and improved fatigue resistance.

Terminal modulus is S in tensile test of fiber.
It is the value (g/d) obtained by dividing the stress increment between a point on the S curve that is 2.4% bowed from the cutting elongation and the cutting point by 2゜4 x 10', and the conditions for the tensile test are as follows: J l5-L
By lol 7.

The composite fiber characterized by the above has a high strength of 7° bQ/d or more, an initial tensile resistance of 60 o/d or more, and an elongation of 20% or less.

More preferable composite fiber properties are strength 8Q/(1 or more, initial tensile resistance surface 7C1/cJ or more, and elongation 8 to 16%), which can be achieved by appropriately combining the above conditions.

The composite fiber is manufactured by the novel method shown below.

In order to obtain the polymer physical properties of the polyester sheath component described above, a polymer consisting essentially of polyethylene terephthalate and having an intrinsic viscosity (η) of 0.75 or more, usually 0.85 or more is used. In addition, in order to obtain fibers with excellent heat resistance,
It is possible to spin polymers with low carboxyl end group concentration.
It is essential. For example, by adopting low temperature polymerization method, polymerization process,
Alternatively, techniques such as adding a capping agent during the spinning process are applied, and the capping agents include, for example, oxazolines, epoxies, carbodiimides, (2) tyrene carbonate, oxalic acid esters, malonic acid esters, and the like.

The polyamide core component polymer has a relative viscosity of 2°8 or more in sulfuric acid,
Usually, a polymer with a high degree of polymerization of 3.0 or more is used.

It is preferable to use two Ek and Struder type spinning machines for melt spinning the polymer. The polyester and polyamide polymers melted in each of the 1x struders are introduced into a composite spinning bag and spun through a composite spinning nozzle into a composite TAN with polyester in the sheath and polyamide in the core.

The spinning speed is 15g0m/min or more, preferably 2000m/min.
The speed should be at least 1/min. Directly below the spinneret, there are more than 101
200°C or more, preferably 260°C within 1 m
The above heating atmosphere is created by providing a heat insulating cylinder, a heating cylinder, etc. After passing through the above heating atmosphere, the spun yarn is quenched and solidified with cold air, and then, after being applied with an oil agent, it is taken off by a take-off roll that controls the spinning speed. Control of the heating atmosphere directly below the spinneret is important in order to maintain spinnability during high-speed spinning.

The taken-off undrawn yarn is normally drawn continuously without being wound up. The birefringence of the undrawn yarn sampled on a take-up roll for the purpose of understanding the physical properties of the undrawn yarn before stretching is 20 x 10-3 or more in the polyamide core, preferably 30
X10' or more, polyester sheath part also 20X10' or more,
Preferably, it is highly oriented with an orientation of 30×10″1 or more.

＾The adoption of fast spinning improves the modulus, dimensional stability, and
It brings about the effect of improving fatigue resistance, but surprisingly, the durability of the core-sheath composite interface is slightly improved. Perhaps, unlike the conventional low-speed spinning method (Comparative Example 1.2 in Section I), in which a highly hygroscopically crystallized polyamide component and an amorphous polyester component are combined, the high-speed spinning method It is thought that the fact that both the polyester component and the polyester component are in a state where oriented crystallization progresses, and that the stretching ratio of the spun pattern is small contributes to the durability of the composite interface.

Next, the undrawn yarn is continuously heated to 180°C or higher, preferably 2°C.
It is hot stretched at a temperature of 00°C or higher.

The stretching is carried out in two or more stages, usually three or more stages, and the stretching ratio is in the range of 1.4 to 3.5 times. The use of such high-temperature thermal stretching according to the present invention also contributes to improving the composite interface durability. The stretching temperature in the third stage of the stretching is low, for example 160
If the stretching temperature is lower than 180°C, interfacial delamination between the polyester sheath component and the polyamide core component may occur during subsequent processes such as weaving and weaving seat belt webbing.

The polyester sheath, polyamide core composite m-fiber having the above characteristics is used as at least the warp, preferably the weft and the warp to obtain a webbing for a seat belt. When other fibers are used for the weft, conditions are set so that the conjugate fibers are present in a larger amount on the surface of the woven webbing than these other fibers.

[Example] Example-1 and 2) Comparative Examples 1 to 3 Intrinsic viscosity (η) 1.05, carboxyl terminal I3I! !
Polyethylene terephthalate (PET) of 10.5eq/106Q and hexamethylene adipamide (N66) containing 0.02% copper iodide and 0.1% potassium iodide.
: Sulfuric acid (relative viscosity ηr 3.3) was melted using a 40φ spinner, introduced into a composite spinning bag, and spun from a core-sheath composite spinneret into a composite yarn with polyethylene terephthalate in the sheath and polyamide in the core. . The proportions of the sheath component and core component were varied as shown in Table 1. The cap used had a hole diameter of 0.4a*φ and 36 holes. The polymer temperature was as follows: polyethylene terephthalate was melted at 295°C, polyamide was melted at 290°C, and the spinning back temperature was set at 30°C.
It was spun at 0°C. A heating cylinder No. 151 was attached directly below the mouthpiece, and the atmosphere inside the cylinder was heated to 290°C. The ambient temperature is the ambient temperature measured at a position 101 points below the mouth surface and 11 points away from the outermost thread.

An annular chimney with a length of 400 m was installed under the heating cylinder, and cold air was blown at 40 m/min at 25° C. from around the yarn at right angles to the yarn to cool it.

Then, after applying an oil agent, the yarn was drawn using a take-up roll rotating at the speed shown in Table 1, and after controlling the yarn speed, the yarn was drawn continuously without being wound. The film was stretched in three stages using five pairs of Nelson type rolls, then subjected to a relaxation heat treatment with 3% relaxation, and then wound up. The stretching conditions were as follows: take-up roll temperature at 60°C, first stretching roll temperature at 120°C, second stretching roll temperature at 190°C, third stretching roll temperature at 225°C.
The tension adjustment roll after stretching was not heated, and the first stage stretching ratio was 70% of the total stretching ratio, and the remainder was divided into two stages for stretching. The yarn was produced by varying the spinning speed, total draw ratio, etc., and the discharge amount was changed in accordance with the spinning speed and draw ratio so that the fineness of the drawn yarn was about 5g0 denier (Example 1
．． 2) Comparative Example 1). Two of the obtained drawn yarns were combined into 10
00 near-neal.

The spinning conditions, the obtained drawn yarn properties, and the 171M structural parameters were compared to polyethylene terephthalate (PET) fibers (100OD to 72F) (Comparative Example 2) and nylon 66
A comparative test was conducted on the fiber (8400-136F) (Comparative Example 3).

Each condition and fiber properties are as shown in Table 1.

(Hereinafter, blank space) Polyester sheath obtained in Example 1 shown in Table 1 above,
The nylon 66-core composite m fiber is ILM used in the seat belt webbing according to the present invention, and has a higher polyester/nylon polymer composition than the polyester sheath and nylon 66-core composite II miscellaneous obtained in Comparative Example 1. Although the ratio (weight pressure) is the same, it has excellent tensile resistance and dry heat shrinkage rate.

Furthermore, the composite fiber obtained in Example 1.2 had an extremely superior dry heat shrinkage rate compared to the polyester fiber obtained in Comparative Example 2'c, and Nylon 66! It has lower elongation than l fiber and has excellent initial tensile resistance.

Example 1.2) [lt
Webbing for seat belts was woven using the

The webbing for seat belts made of the fibers of Example 1.2 according to the present invention was prepared from I obtained in Comparative Examples 1 to 3.
As a result of comparison with the webbing for a seat belt made of I fiber, the webbing for a seat belt made of Example 1.2 of the present invention has approximately the same strength as the webbing for a seat belt made of Comparative Example 2.3, and has a modulus of elasticity of , modulus, dimensional stability, and light resistance are approximately the same as those of Comparative Example 2 and superior to those of Comparative Example 3, and shock absorption resistance and durability are approximately the same as those of Comparative Example 3, It was superior to that of Comparative Example 2.

In particular, as a result of repeated tests of storing the webbing in a retractor and taking it out from the retractor, the webbing for a seatbelt made of Example 1.2 of the present invention was found to have a wider width than the webbing for a seatbelt made of Comparative Example 2. It has excellent fuzzing and abrasion resistance at the edges of the direction,
Improves durability.

In particular, the webbing for seat belts made of Example 1.2 of the present invention, compared to the webbing for seat belts made of Comparative Example 3, showed that the webbing The dimensional stability in the dimensional direction was extremely excellent.

The webbing for seat belts made of Example 1.2 of the present invention is easier to store in a retractor than the webbing for seat belts made of the so-called normal polyester sheath and nylon 66-core composite fiber obtained in Comparative Example 1. The results of the repeated tests taken out of the webbing from the retractor revealed that seatbelt webbing has certain characteristics such as fuzzing at the edges in the width direction, abrasion resistance, 1st impact absorption resistance, dimensional stability in the direction of thickness, and strength reduction. It was superior in all its characteristics.

[Effects of the Invention] The webbing for seat belts according to the present invention has properties desired as webbings for seat belts, such as strength, abrasion resistance, l1ff absorption resistance, light resistance, heat resistance, dimensional stability, elastic modulus, and modulus. It has many physical properties, and it greatly improves durability.

Claims (2)

[Claims] (1) In webbing for seat belts, the warp yarns used to weave the webbing include a core component mainly composed of polyamide, and a core component surrounding the core component mainly composed of polyester made of ethylene terephthalate. It is a sheath-type composite fiber, the proportion of the polyester sheath component in the core-sheath type composite fiber is 10 to 70% by weight, the strength of the composite fiber is 7.5 g/d or more, the elongation is 20% or less, and the initial tensile strength is A webbing for a seat belt, characterized in that it is woven using fibers having a resistance of 60 g/d or more and a dry heat shrinkage rate of 7% or less. (2) The webbing for a seat belt according to claim (1), characterized in that it is woven using core-sheath composite fibers made of polyamide and polyester for the warp and weft.