JPH09209223A - High-strength multifilament yarn, its production and non-air permeable high-strength cloth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-strength multifilament satisfying lightness, softness, storable property and mechanical property respectively more than obtained by conventional techniques as a multifilament yarn for a non-coated air bag and giving cloth having sufficient non-air permeable property by improving of raw yarn. SOLUTION: This high-strength multifilament yarn has >=6.5g/d strength, >=200 denier yarn size, <=10 denier single fiber size, 30-80% content of single fiber of one kind in filament yarns having different single fiber cross section shape and >=3.0% boiling water shrinkage difference and/or 150 deg.C dry heat shrinkage difference of a filament yarn having different single fiber cross section shape. This combined multifilament yarn preferably contains a round cross section filament yarn and a modified cross section filament yarn having a convex part in a cross section of a single filament, and is obtained by a method of in-spinning combining, such as melt spinning of a polymer having high viscosity from melt spinning spinnerets having more than two kinds of spinning holes of different hole shape, cooling and winding up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength multifilament yarn useful for outdoor tents, bags, airbag base fabrics and the like. More specifically, the present invention relates to a high-strength multifilament yarn that can be made into a high-strength fabric that is highly lightweight and has excellent flexibility and is also excellent in non-breathability, and is particularly useful as a raw yarn for a non-coated airbag.

[0002]

2. Description of the Related Art In recent years, an airbag has been rapidly installed as a vehicle occupant protection safety device. Since this airbag is normally stored in a narrow space such as a steering wheel or an instrument panel, one of the required performances is to reduce the storage volume.

[0003] Therefore, the airbag base cloth should be as foldable as possible within a range satisfying the mechanical characteristics,
Efforts have been made in the past to minimize storage volume. For example, in the rubber-coated base fabric, the coating rubber is being changed from a polychloroprene-based rubber to a silicone-based rubber which can reduce the coating amount of the rubber coat and form a flexible rubber-coated base fabric.

On the other hand, in order to ensure the safety of the occupants of the automobile, it is desired to increase the mounting rate of the airbag, and as one of the driving forces, it is possible to reduce the price of the entire airbag system. Required for airbags. Therefore, in order to further reduce the cost of the airbag base fabric, development of a non-coated base fabric is being promoted.

The non-coated base fabric is also advantageous from the viewpoints of softening the base fabric for airbags and improving the storability and lightness, and early establishment of technology as a base fabric for next-generation airbags is required. ing. However, there is a big problem that it is difficult to suppress the air permeability of the base fabric to a sufficient level when the unwoven base fabric is used as it is for the yarn used for the airbag.

Therefore, various proposals have been made in order to reduce the air permeability of the base fabric for non-coated airbags, for example, JP-A-3-137245 and JP-A-64-7.
No. 0247 and Japanese Patent Laid-Open No. 3-134245.

That is, in Japanese Unexamined Patent Publication No. 3-137245, in order to control gas permeability, which is an important property as a base fabric for non-coated airbags, a high-density woven fabric is used, and further, shrinking process, heat setting calendering process, etc. Is applied to produce a base fabric for a non-coated airbag.

In Japanese Patent Laid-Open No. 64-70247, a base fabric having a basis weight of 250 g / m ² or less is calendered to produce a non-airbag base fabric having a breathability of 5 cc / cm ² / sec or less. It is disclosed to do.

In Japanese Patent Laid-Open No. 3-134245, a woven fabric having a symmetrical structure subjected to calendering is used.
Disclosed is a base fabric for a non-coated airbag, which has a fineness of 400 dtex and is made of a highly shrinkable yarn.

[0010]

However, in each of the above-mentioned prior arts, in order to improve the performance as a non-coated airbag base fabric, particularly the non-breathability, various woven fabrics may be subjected to various post-treatments. It is necessary, and there is a problem that it is difficult to reduce the price because of the complexity of the process. Therefore, in order to reduce the price, it has been earnestly desired to improve the non-air permeability of the base fabric by improving the raw yarn.

Further, it has been proposed in Japanese Patent Laid-Open No. 4-193647 to manufacture a base fabric for an air bag by using an entangled yarn composed of filaments having a non-circular cross section, but this method also sufficiently enhances the non-air permeability. It was difficult.

Therefore, in order to solve the above-mentioned problems in the prior art, the present invention satisfies the lightness, flexibility, storability, and mechanical characteristics equal to or higher than those of the prior art as a multifilament yarn for non-coated airbags. The main object of the present invention is to provide a high-strength multifilament yarn capable of obtaining a fabric having sufficient non-breathability by improving the raw yarn.

[0013]

The above object can be achieved by the following means.

A multi-filament multifilament yarn composed of two or more types of filament yarns having different single yarn cross-sectional shapes, having a strength of 6.5 g / d or more and a yarn fineness of 20.
0 denier or more and single yarn fineness of 10 denier or less,
The percentage of the number of single yarns among the filament yarns having different single yarn cross-sectional shapes is 30 to 80%, and the difference in boiling water shrinkage of the filament yarns having different single yarn cross-sectional shapes and / or 15
A high-strength multifilament yarn having a difference in dry heat shrinkage of 0 ° C of 3.0% or more.

The multifilament yarn is preferably a raw yarn for a non-coated airbag. Also,
It is preferable that the two or more kinds of filament yarns having different single yarn cross-sectional shapes include a round cross-section filament yarn and a modified cross-section filament yarn having a recess in the single-yarn cross-sectional shape. The ratio of the number of yarns of the yarn is preferably 35 to 80%. The cross-sectional fiber shape of the modified cross-section filament yarn is preferably asymmetric. Furthermore,
It is preferably composed of a polyester filament having an intrinsic viscosity of 0.8 or more and / or a polyamide filament having a sulfuric acid relative viscosity of 2.6 or more.

The multifilament yarn can be produced by a method of melt-spinning a high-viscosity polymer from a melt-spinning spinneret having two or more kinds of spinning holes having different hole shapes, cooling and taking-in a mixed fiber during spinning. It can be knitted and woven and heat-shrinked to obtain a non-breathable high-strength fabric.

In the conventional non-coated airbag base fabric, various post-treatments are required to achieve sufficient non-breathability. In the unprocessed non-coated airbag base fabric that has not been post-processed, it is important to shrink the voids by shrinking the raw yarn to increase the fabric density. Therefore, a study was conducted focusing on the relationship between the woven structure and the air permeability, and as a cause that the air permeability of the unprocessed non-coated airbag base fabric cannot be sufficiently increased by the conventional technique, the warp and the weft are at right angles. It was found that the filament packing rate is still insufficient in the vicinity of the crossing intersection.

That is, since the conventional yarn for air bag is a filament yarn composed of one kind of filament and having a good converging property, the filaments in the warp yarn are most closely packed by the tension applied in the fiber axial direction in the weaving process. In addition, the filaments in the weft are close-packed at the warp and weft intersections where the warp and the weft intersect at a right angle due to the beating operation, and as a result, the vicinity of the warp and weft intersections is close. In the above, it was found that it is difficult to close the gap between the yarn and the yarn with the filament, and gas leaks from this gap and the non-air permeability cannot be sufficiently enhanced.

Therefore, the present invention is a multi-filament multifilament including bulky modified cross-section filaments, which is composed of two or more kinds of filament threads having different single-filament cross-sectional shapes and different shrinkages of 3% or more. This is based on the new finding that the problem of the yarn-thread relationship gap in the vicinity of the intersection of the warp and weft can be solved by using the yarn.

The high-strength multifilament yarn of the present invention is
A mixed multifilament yarn composed of two or more types of filament yarns having different single yarn cross-sectional shapes,
The strength is 6.5 g / d or more, the yarn fineness is 200 denier or more, the single yarn fineness is 10 denier or less, and the ratio of the number of single yarns of one kind among filament yarns having different single yarn cross-sectional shapes is 3
It is necessary that the difference in boiling water shrinkage and / or the difference in dry heat shrinkage at 150 ° C. of the filament yarns of 0 to 80% and the cross-sectional shape of the single yarn is 3.0% or more.

By weaving the base fabric for a non-coated airbag using the multifilament yarn satisfying these requirements, the non-air permeability can be greatly improved without post-processing. The reason is considered as follows.

Since filaments having different cross-sectional shapes are in contact with each other, close packing is prevented, and the entire fiber bundle is not excessively packed and has a proper volume space. Moreover, since two or more types of filaments having different cross-sectional shapes have different shrinkage characteristics due to heat, a difference in the degree of shrinkage occurs during scouring and / or heat setting after weaving, which increases the bulkiness of the entire multifilament. The apparent volume of the yarn increases. Combined with these bulkiness effects, the gap around the warp-weft crossing portion of the non-coated airbag base fabric is closed, and the non-air permeability can be greatly improved.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The mixed filament multifilament yarn of the present invention is composed of two or more kinds of filament yarns having different single yarn cross-sectional shapes. On the other hand, in the case of a multifilament yarn having one type of single yarn cross-sectional shape, as described above,
The filaments are packed closest to each other due to the tension in the fiber axis direction to reduce the volume of the fiber bundle, and to close the gap between the yarns in the non-coated airbag base fabric, especially at the intersection of the warp and the weft. However, it is difficult to increase the non-breathability.

In the multifilament yarn of the present invention, the difference in boiling water shrinkage between filament yarns having different cross-sectional shapes and /
Alternatively, the difference in dry heat shrinkage at 150 ° C. needs to be 3.0% or more. The difference in boiling water shrinkage and / or the difference in dry heat shrinkage at 150 ° C between filament yarns having different cross-sectional shapes is 3.0.
If it is less than%, the difference in shrinkage that occurs during scouring or heat setting is too small, so that the bulkiness of the entire multifilament yarn cannot be sufficiently increased, the volume space of the yarn cannot be increased, and it is for non-coated airbags. The gap at the intersection of the warp yarn and the weft yarn in the base cloth cannot be sufficiently closed, and the air impermeability cannot be sufficiently enhanced.

In order to have a difference in shrinkage characteristic between the filament yarns, the following method may be used. For example,
A difference in shrinkage characteristics may be generated by a method of fiber mixing during spinning, in which filaments having different cross-sectional shapes are melt-spun from the same spinneret, simultaneously cooled and drawn. In this case, in the yarn cooling from the spinning to the take-up, a difference in cross-sectional shape, that is, a difference in the cooling rate due to a difference in the fiber surface area, and as a result, a difference in the degree of orientation between the drawn filaments occurs, This causes a difference in shrinkage characteristics.

As another method, filaments having different cross-sectional shapes are spun separately, and the filaments having different shrinkage characteristics are made by different conditions such as the draw ratio and the draw temperature during drawing, and these are mixed. May be.

The multifilament yarn of the present invention has a yarn fineness of 200 denier or more and a strength of 6.
It is required to be 5 g / d or more. If the yarn fineness is less than 200 denier or the strength is less than 6.5 g / d, the tear strength of the fabric obtained by weaving is low and it cannot be used in the industrial field.

The single yarn denier of the multifilament yarn of the present invention is required to be 10 denier or less, particularly 1.0
10 denier is preferred. When the single yarn denier exceeds 10 denier, the fabric obtained by weaving is inferior in flexibility, and it is difficult to put it into practical use because it cannot be folded and stored in an air bag. On the other hand, if the single yarn denier is less than 1.0 denier, the difficulty in production increases, such as the occurrence of fluff due to rubbing in the handling and processing of the raw yarn.

The ratio of the number of single yarns among filament yarns having different cross-sectional shapes of single yarns constituting the mixed fiber multifilament yarn (ratio to the number of single yarns of the whole mixed fiber multifilament yarn) is 30 to 80%. It is necessary to be. In particular, in the case where a round cross-section filament yarn and a modified cross-section filament having a recess in the single cross-sectional shape are included, the number of single yarns in the round cross-section filament is 35 to 80.
%. When it is out of this range, the tear strength of the woven base fabric is lowered, sufficient bulkiness is difficult to be obtained, and it is difficult to sufficiently enhance the non-air permeability of the fabric.

The cross-sectional shape of the single filament constituting the multifilament yarn of the present invention may be a mixture of two or more kinds of filaments having different cross-sectional shapes of the monofilaments. And a modified cross-section filament having The cross-sectional shape of this modified cross-section filament yarn is T-shaped, Y-shaped, U-shaped, or V-shaped.
It may be symmetrical with a single yarn cross section having a recess like a V-shaped cross section, but in order to control the closest packing of the filament, a left-right asymmetrical shape like a V-shaped cross section or a C-shaped cross section Is preferred.

The multifilament yarn of the present invention is preferably a polyester filament and / or a polyamide filament, and in particular, from the viewpoint of obtaining high strength, the polyester filament and / or sulfuric acid having an intrinsic viscosity of 0.8 or more. It is preferably composed of a polyamide-based filament having a relative viscosity of 2.6 or more. Examples of the polyester filaments include filaments made of polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., and polyamide filaments include polyhexamethylene adipamide,
Examples of the filament include polytetramethylene adipamide and polycapramide.

The above polyester-based filaments and polyamide-based filaments may be added with other copolymerization components and additives such as heat-resistant agents, flameproofing agents, antioxidants and pigments, as long as they do not impair their original properties. May be contained in a small amount such as 10% by weight or less, if necessary.

The mixed multifilament yarn of the present invention described above can be manufactured by the following method.

For example, it can be obtained by separately spinning and drawing two or more types of filament yarns having different cross-sectional shapes and then mixing them, or spinning and drawing two or more types of filament yarns having different cross-sectional shapes from the same spinneret. Alternatively, two or more types of filament yarns having different cross-sectional shapes can be spun separately and mixed at the time of drawing, and can be appropriately selected according to the actual condition of the equipment.

As a production example of the multifilament yarn of the present invention, a method of melt-spinning two or more kinds of filament yarns having different cross-sectional shapes from the same spinneret, cooling, drawing and drawing will be described below.

A polyester-based polymer or polyamide-based polymer obtained by polymerization by a conventional method is subjected to a high degree of polymerization, if necessary, to prepare a spinning tip. When using a copolymerization component, a heat-resistant agent, a flameproofing agent, an antioxidant, a pigment, etc., they may be added by a usual method such as addition during polymerization or chip blending.

The above-mentioned spinning chips are melted by an extruder, weighed by a gear pump, guided to a spinning bag, passed through a foreign matter removing filter, and then discharged from a spinneret.

The number of spinning holes in the spinneret is 3 for all the holes in the spinneret.
It is composed of round holes occupying 5 to 80% and left-right asymmetric spinning holes occupying the remaining holes. The left-right asymmetric spinning hole may be appropriately selected from a katakana g-shape, a katakana s-shape, a left-right asymmetric hole shape having no regularity, and the like.

The arrangement of the spinning holes of the spinneret may be appropriately selected from a ring arrangement, a whole surface arrangement, a staggered arrangement, etc., and a spinning hole arrangement having a different cross-sectional shape may be appropriately selected from a random arrangement, a row arrangement and a block arrangement. .

The discharged yarn is delayed and cooled through a heating atmosphere region installed immediately below the spinneret. After that, it is introduced into the cooling zone, blows cooling air, and is passed through a spinning cylinder to form a yarn.

The temperature of the heating atmosphere region is 120 to 350.
C., the length thereof may be 5 to 50 cm, and the conditions of the heating atmosphere region may be selected according to the setting conditions such as the viscosity of the spun yarn, the thickness of the filament, the draft ratio, the number of filaments and the like.

In the cooling area, 120 such as normal temperature air is used.
What is necessary is just to blow the gas below 15 degreeC at the speed of 15-50 m / min. The condition of this cooling zone also depends on the viscosity of the spun yarn,
It may be selected according to the setting conditions such as the thickness of the filament, the draft ratio, the number of filaments, and the like.

The spun yarn that has passed through the heating atmosphere region and the cooling region and is cooled and solidified by cold air is provided with a spinning oil agent and is 2000 m / min or less, preferably 1500 m.
After being taken up by a roll rotating at a speed of not more than 1 minute, the film is continuously or once wound and then stretched. Spinning speed is 20
If it exceeds 00 m / min, fluff during yarn production and yarn breakage during drawing increase, which is not preferable.

In order to make the shrinkage characteristic difference between the filament yarns 3.0% or more in this manufacturing method, it is sufficient to control the conditions that cause the shrinkage characteristic difference such as the cooling rate difference in the process up to the take-up. For this purpose, the polymer viscosity, the shape of the spinning hole, the thickness of the filament, the number of filaments, the conditions of the heating atmosphere region, the conditions of the cooling region, the spinning speed and the like may be appropriately controlled within the above range.

The stretching is preferably multi-stage stretching, and the first stage stretching distribution is preferably in the range of 50 to 80% of the total stretching distribution. If it is out of this range, fluff and yarn breakage may occur frequently.

The yarn temperature used for the first stage drawing is 150 ° C.
The temperature is preferably below, and when the yarn temperature used for the first stage drawing exceeds 150 ° C., crystallization progresses and the drawing after the second stage becomes difficult. The stretching and heat setting temperatures for the second and subsequent steps may be 150 ° C. or higher, more preferably 170 ° C. or higher. As a method for applying heat necessary for drawing the yarn, known methods such as roll heating, steam, and hot liquid are used.

The drawn yarn is subjected to a relaxation treatment as necessary or wound up as it is.

As described above, in order to industrially easily produce the mixed multifilament yarn suitable for increasing the non-air permeability of the cloth, the mixed fiber containing two or more kinds of filaments having different cross-sectional shapes is used. The yarn is mixed during spinning,
It is preferable to spin and draw at a relatively low speed (2000 m / min or less).

When the mixed multifilament yarn thus obtained, which is suitable as the base yarn for the non-coated airbag of the present invention, is used as the base yarn for the base fabric for the non-coated airbag, the gap between the intersecting portions of the warp and the weft is obtained. It can be significantly occluded and a sufficiently high non-breathability can be achieved.

[0050]

The present invention will be described in detail below with reference to examples. The physical properties in the examples are values measured as follows.

A. Strength (T): Sample at 20 ° C, 65
After leaving it in a temperature control room of% RH for 24 hours or more, an S-S curve was obtained at a test length of 25 cm and a take-up speed of 30 cm / min using a "tensilon" tensile tester manufactured by Orientec Co., Ltd.
Calculate strength.

B. Polyamide relative sulfuric acid viscosity (ηr):
Dissolve 1 g of a sample in 100 ml of 98% sulfuric acid, and measure with an Ostwald viscometer at 25 ° C.

C. Intrinsic viscosity (IV) of polyester:
Dissolve 8 g of the sample in 100 ml of orthochlorophenol, and measure the solution viscosity (η) using an Ostwald viscometer at 25
The measurement is performed at 0 ° C., and the intrinsic viscosity (IV) is calculated by the following approximate expression. IV = 0.0242η + 0.2634

D. Boiling water shrinkage difference (Δw): 1 single yarn each having the same cross-sectional shape from the mixed fiber multifilament yarn
Sampled every 0 to make a wrinkle sample, 20 ℃, 65
After leaving it in the temperature control room of% RH for 24 hours or more, the sample was adjusted to 0.
The length L ₀ is measured by applying a load corresponding to 1 g / d.
Next, this sample was treated in boiling water for 30 minutes in a tension-free state, then left in the temperature control chamber for 4 hours, and the load was applied again to measure the length L ₁ . The boiling water shrinkage rate w is calculated from the lengths L ₀ and L ₁ by the following equation. w = [(L ₀ −L ₁ ) / L ₀ ] × 100 (%) The average value of 10 samples with the same cross-sectional shape is taken as the boiling water shrinkage rate w 1 of that sample, and for other samples with other cross-sectional shapes Similarly, the boiling water shrinkage rate w2 is obtained, and the difference is defined as the boiling water shrinkage rate difference (Δw).

E. 150 ° C dry heat shrinkage difference (Δs):
Sampled in the same manner as above to make a wrinkled sample,
After being left in a temperature control room of 65% RH for 24 hours or more, a load corresponding to 0.1 g / d is applied to the sample and the length L ₀ is measured. Next, this sample is left in an oven at 150 ° C. for 30 minutes without tension, then taken out of the oven and left in the temperature control chamber for 4 hours, and the above load is applied again to measure the length L ₁ . From those lengths L ₀ and L ₁ to 150 ° C. dry heat shrinkage s is calculated by the following formula. s = (L ₀ −L ₁ ) / L ₀ × 100 (%) The average value of 10 samples having the same cross-sectional shape was 15 of the samples.
The dry heat shrinkage of 0 ° C. is defined as s1, and the dry heat shrinkage of s2 at 150 ° C. is similarly calculated for samples having other cross-sectional shapes.
It is defined as the difference in dry heat shrinkage at 50 ° C. (Δs).

F. Fabric flexibility: JIS-L-10
The bending resistance is measured by 96 (45 ° cantilever method).

G. Non-breathability of fabric: JIS / L10
The non-air permeability is measured by the 96.6.27A method and displayed according to the following criteria.

When the non-air permeability is less than 0.5 cc / cm ² / sec, good (∘), 0.5 to 0.7 cc / cm
In case of 2 / sec, a little bad (△), 0.7 cc /
A case (cm2 / sec or more) is regarded as a defect (x).

H. Tensile strength of cloth: JIS K6
According to 328 (slip method), measurement is performed on a fabric sample having a width of 3 cm. The tensile strength is the average value of the values obtained in the warp direction of the fabric and the values obtained in the weft direction of the fabric.

I. Fabric cover factor (K):
It is a value obtained by the following formula from the product of the fabric constituent density and the square root of the fineness of the fiber yarn. K = Nw × Dw ^1/2 + NF × DF ^1/2 where Nw: warp density (threads / inch), Dw: warp fineness (denier), NF: weft density (threads / inch),
DF: Weft yarn fineness (denier).

[Examples 1 to 4 and Comparative Examples 1 to 4] 98% sulfuric acid relative viscosity is 3.5, and phosphorus is 100 p as an antioxidant.
Nylon 66 chips containing pm, 80 ppm of copper and 0.1% by weight of potassium iodide were melted by an extruder type spinning machine. The molten polymer was filtered in a spin pack and spun through the spinneret of the spinneret. The spinneret has 72 spinning holes.
There were holes, and the spinning holes were arranged in a block with a round cross-section and a katakana K shape. The ratio of the number of spinning holes having a circular cross-sectional shape and the shape of a katakana G-shaped was changed as shown in Table 1.

However, in Comparative Example 1, the spinning holes of the spinneret had a round cross section and a triangular cross section, and in Comparative Example 4, the number of spinning holes of the spinneret was 40 holes.

The spun yarn was installed just below the spinneret and had a length of 30c.
After passing through a slow cooling zone having a temperature of 300 m and a temperature of 300 ° C., cold air of 18 ° C. was blown by a uniflow type chimney to cool and solidify, an oil agent was applied, and the product was taken by a take-up roll rotating at 900 m / min. Then, 5% stretch was applied between the take-up roll and the yarn supplying roll to align the take-up yarns.

Next, the above yarn was sent to the drawing step and continuously drawn and heat-treated. The stretching heat treatment was carried out by a method of heat setting after two stages of heat stretching, followed by one stage relaxation treatment and winding. The take-up roll is not heated, the yarn feeding roll is 40 ° C., the first drawing roll is 120 ° C., the second drawing roll is 220 ° C., the heat setting roll is 235 ° C., and the relaxing roll after drawing. Was heated to 150 ° C.

The stretching ratio was 75% of the total stretching ratio in the first stage, and the rest was stretched in the second stage with a relaxation rate of 8%. Immediately before winding, the interlace was wound so that the number of interlaced fibers was about 40 per 1 m.

The mixed filament multifilament yarn (sulfuric acid relative viscosity 3.5) obtained was 420 denier and 72 yarns, and their physical properties are as shown in Table 1. The cross section of the V-shaped irregular cross-section filament yarn therein was as shown in FIG.

This mixed multifilament yarn was made into a warp beam having 2100 warp yarns, and was then manufactured by Tsuda Koma Co., Ltd.
Weaving was performed using JL at a weft driving speed of 1000 m / min. The obtained raw machine is scoured at 60 to 70 ° C, and 110 ° C.
After drying at 180 ° C., heat setting was performed at 180 ° C. to obtain a non-coated airbag base fabric with a cover factor of 2000, and the flexibility, non-air permeability, and tensile strength were measured, and the results are also shown in Table 1.

[0068]

[Table 1]

As shown in Table 1, with the mixed fiber multifilament yarn of the present invention, a base fabric for an air bag excellent in flexibility, air permeability and tensile strength was obtained. On the other hand, in Comparative Example 1, the difference in shrinkage between filament yarns was too small, and in Comparative Example 2, the fiber mixing ratio was outside the scope of the present invention and the fiber mixing effect was insufficient. , Could not increase the non-breathability. In Comparative Example 3, the tensile strength was inferior because the mixed fiber ratio was too low outside the present invention. Further, in Comparative Example 4, the single yarn fineness was too large, and thus the flexibility was poor.

Examples 5 to 8 and Comparative Examples 5 to 6 Polyethylene terephthalate having an intrinsic viscosity of 1.2 and a chip moisture content of 0.002% or less was melted by an extruder type spinning machine. The molten polymer was filtered in a spin pack and spun through the spinneret of the spinneret. The spinneret has 144 holes for spinning,
The spinning holes were block-arranged in a circular cross-sectional shape and a Katakana G-shape. The ratio of the circular cross-sectional shape and the katakana G-shaped spinning hole was changed as shown in Table 2.

The spun yarn was installed directly below the spinneret and had a length of 30c.
After passing through a slow cooling zone having a temperature of 300 m and a temperature of 300 ° C., cold air of 18 ° C. was blown by a uniflow type chimney to cool and solidify, an oil agent was applied, and the product was taken by a take-up roll rotating at 900 m / min. Then, 5% of stretch was applied between the take-up roll and the yarn supplying roll to align the take-up yarns.

Next, the yarn was sent to the drawing step and continuously drawn and heat-treated. The stretching heat treatment was performed by a method of performing a two-stage hot stretching and then a one-stage relaxation treatment. The take-up roll is not heated, the yarn feeding roll is 60 ° C, and the first drawing roll is 11
The heating was performed at 0 ° C., the second stretching roll was heated at 230 ° C., and the relaxing roll after stretching was at room temperature.

The stretching ratio was 3.56 for the first step and 1.25 for the second step, and the relaxation rate was 4%. Immediately before winding, an interlace was wound so that the number of interlaced fibers was about 50 per 1 m.

The mixed-fiber multifilament yarn (intrinsic viscosity 1.0) obtained by the above method had 420 denier and 144
The physical properties of fil were as shown in Table 2.
This mixed fiber multifilament yarn was used as a warp beam having 2100 warp yarns and was woven at a weft driving speed of 1000 m / min using WJL manufactured by Tsuda Koma Co., Ltd.

The obtained greige was subjected to a scouring step at 60 ° C., then dried and heat set at 180 ° C. to obtain a non-coated airbag base fabric, and its flexibility, non-air permeability and tensile strength were measured. The results are also shown in Table 2.

[0076]

[Table 2]

As shown in Table 2, with the mixed fiber multifilament yarn of the present invention, a base fabric for an airbag was obtained which was excellent in flexibility, air permeability and tensile strength. On the other hand, in Comparative Example 5, the fiber mixing ratio was outside the scope of the present invention and the fiber mixing effect was insufficient, so the non-air permeability could not be increased. In Comparative Example 6, the tensile strength was inferior because the fiber mixture ratio was too low outside the present invention.

[0078]

The mixed fiber multifilament yarn of the present invention is
It has high strength, flexibility and appropriate bulkiness, and is particularly useful as a raw yarn for non-coated airbags. That is, when weaving a non-coated airbag base fabric from the mixed fiber multifilament yarn of the present invention, in the weaving process and the like, the closest packing of filaments in the multifilament yarn is prevented,
Since an appropriate volume space can be maintained as the entire fiber bundle, the gap between the intersecting portions of the warp yarns and the weft yarns of the non-coated airbag base fabric can be significantly reduced, and the non-air permeability can be significantly improved. In addition, this makes it possible to eliminate the need for post-processing to improve the non-air permeability, and to reduce the cost of manufacturing an airbag.

Further, even if the air-impermeable property is enhanced, the flexibility and mechanical properties required for the airbag base fabric are not deteriorated, so that the flexibility, storability, mechanical properties and non-air-permeable property are obtained. It is possible to obtain a base fabric for an airbag that is excellent in both.

The multifilament multifilament yarn of the present invention is also useful for outdoor tents, bags and the like, making use of the above characteristics.

[Brief description of drawings]

FIG. 1 is a fiber cross-sectional view showing one embodiment of a modified cross-section filament having recesses in the single-yarn cross-section shape used in the present invention.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location D03D 15/00 D03D 15/00 D

Claims (8)

[Claims] 1. A mixed fiber multifilament yarn composed of two or more kinds of filament yarns having different single yarn cross-sectional shapes, having a strength of 6.5 g / d or more, a yarn fineness of 200 denier or more, and a single yarn. The fineness is 10 denier or less, the ratio of the number of single yarns among the filament yarns having different single yarn cross-sectional shapes is 30 to 80%, and the difference in boiling water shrinkage between the filament yarns having different single yarn cross-sectional shapes and And / or a high-strength multifilament yarn having a difference in dry heat shrinkage of 150 ° C. of 3.0% or more. 2. The high-strength multifilament yarn according to claim 1, wherein the multifilament yarn is a raw yarn for a non-coated airbag. 3. The two or more kinds of filament yarns having different single yarn cross-sectional shapes include a round cross-section filament yarn and a modified cross-section filament yarn having recesses in the single-yarn cross-sectional shape. The high-strength multifilament yarn according to 2. 4. The high-strength multifilament yarn according to claim 3, wherein the proportion of the number of round cross-section filament yarns in the multifilament yarn is 35 to 80%. 5. The high-strength multifilament yarn according to claim 3, wherein the cross-sectional shape of the modified filament yarn is bilaterally asymmetric. 6. A polyester-based filament having an intrinsic viscosity of 0.8 or more and / or a polyamide-based filament having a sulfuric acid relative viscosity of 2.6 or more, as claimed in claim 1, 2, 3, 4 or 5. High strength multifilament yarn. 7. The method according to claim 1, 2 or 3, wherein a high-viscosity polymer is melt-spun from a melt-spinning die having two or more kinds of spinning holes having different hole shapes, cooled, and taken up by a method of mixing fibers during spinning.
A method for producing a high-strength multifilament yarn, comprising producing the high-strength multifilament yarn according to 3, 4, 5 or 6. 8. A non-breathable high-strength fabric obtained by knitting and weaving the high-strength multifilament yarn according to claim 1, 2, 3, 4, 5 or 6 and heat shrinking.