JPH07258940A - Ultrafine fiber structure having high strength, its production and conjugate fiber having high strength - Google Patents

Abstract

PURPOSE:To produce a base cloth for non-coat air bag composed of an ultrafine high-strength multifilament and having excellent mechanical strength, flexibility and foldability and low gas permeability. CONSTITUTION:A high-strength sea-island conjugate fiber having a single fiber fineness of >=3de, a crystallite volume of >=8X10<4>Angstrom <3>, a meridian long-period of >=120Angstrom , a crystal orientation of >=0.9, an amorphous part orientation of >=0.975 and a tensile strength of 2 T g/de is produced by using a PET having an intrinsic viscosity of >=1.0 as the island component and a PET copolymerized with a sulfoisophthalic acid salt as the sea component, extruding both components in molten state, spinning the molten extrudate by slowly cooling in a hot atmosphere of 200-350 deg.C under the spinneret and drawing the spun fiber at a draw ratio of >=3 before winding. A multifilament of the fiber having a total fineness of 100-1,000de (preferably 180-450de) is woven at a cover factor K of >=1,900 and the sea-component is removed to obtain a base cloth for non-coat air bag, composed of ultrafine multifilament having a single fiber fineness of <0.8de, a tensile strength of >=6.5g/de and an elongation of >=15%, exhibiting excellent tensile strength and flexibility of the cloth and having a gas transmission rate of <=5.0cc/sec/cm under a pressure head of 1.27cm water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber structure suitable for use in industrial materials. More specifically, the present invention relates to a fiber structure that has excellent mechanical strength and excellent flexibility and that can be manufactured with good spinnability and processability. In particular, the present invention relates to an industrial woven or knitted fabric which also has low air permeability and is particularly useful as a base fabric for an airbag.

[0002]

Structures made of synthetic fibers are widely used in various industrial material fields. For example, as a rubber reinforcing material for tires, V-belts, conveyor belts, hoses, etc.
As woven and knitted fabrics for canvas, tents, tarpaulins, curing sheets, seat belts, airbags, fishing nets,
Widely used as ropes and sewing threads.

Conventionally, as the yarn used in the fiber structure for the above purpose, a yarn having a single yarn fineness of 5d or more has been generally used. This is because a single yarn fineness of a certain level or more is required to easily produce a high-strength yarn, and a larger single yarn fineness is required to reduce the specific surface area in order to suppress deterioration from the surface. This is because it is effective.

However, with the widespread use of textile-related industrial materials such as canvas, tents, tarpaulins, and airbags in recent years, these fiber structures must be strong, lightweight, and flexible. Have also been requested.

Due to this demand, various improvements and proposals have been made in each application, such as reducing the total fineness and the single yarn fineness.

[0006] For example, in the case of a base fabric for an air bag, first of all, it is required to have a low gas permeability and a high mechanical strength which are necessary for smooth expansion upon impact. Especially, the face should not be scratched or scratched, and it can be stored compactly.
It is also required that the dimensions do not change during installation on the vehicle body for a long time.

However, it is difficult to satisfy all of these required characteristics at the same time. For example, in order to suppress gas permeability among the items required for the airbag base fabric, it is sufficient to make the base fabric thicker. On the contrary, if the base fabric is made thicker, the compactness at the time of storage will be improved. Worse, and
There is a problem that the impact force when contacting the human body is increased and the face is easily scratched and damaged. in this way,
Contrary characteristics are required in the design of the base cloth.

Typical air bag base fabrics developed so far are, for example, single yarn fineness 4 to 7d and total fineness 4
A base fabric (hereinafter referred to as a non-coated product) simply composed of a nylon yarn of 00 to 1000 d, or a base fabric coated with a resin such as chloroprene or silicone (hereinafter referred to as a coated product) (JP-A-3) No. 243442).

These air bag base fabrics are excellent in suppressing gas permeation, but since the total fineness and the single yarn fineness of the filaments constituting the base fabric are large, the fabric is hard and lacks in flexibility. As a result, the compactness is poor and the impact force is large. Further, in the case of a coated product, there is a problem that the manufacturing process is complicated, particularly uniform resin coating is difficult, and compactness during storage is poor.

Various proposals have been made to solve the above problems. For example, Japanese Unexamined Patent Publication No. 1-10484
As described in Japanese Patent Publication No. 8, by reducing the total fineness of the multifilaments constituting the base cloth and reducing the thickness of the base cloth,
There has been an attempt to soften the base cloth and to give it compactness when stored.

However, simply reducing the total fineness significantly increases the gas permeability, so it is necessary to compensate for the decrease in gas permeability with a resin coating, and as a result, compactness during storage cannot be improved.

Further, there is a method of lowering the total fineness and weaving the woven fabric at a higher density in order to reduce the gas permeability and improve the compactness during storage.
With the usual single yarn fineness, no matter how small the total fineness is, there is a limit to the improvement of the flexibility of the fabric, and it is difficult to improve the flexibility to a satisfactory value.

Further, in JP-A-64-41438, a strength of 8.5 is provided in order to improve the foldability of the coated product.
A base fabric for an air bag has been proposed which is composed of fibers having a single yarn fineness of 3 d or less and a g / d or more. Furthermore, JP-A-4-21
No. 4437 discloses 4 dtex or less, total fineness of 250 to 4
A non-coat type airbag base fabric made of 00 dtex polyethylene terephthalate multifilament has been proposed.

However, these techniques are intended to reduce the single yarn fineness to about 2d as described in those examples, and sufficiently improve the flexibility and foldability of the base fabric. It was difficult. Further, since the fibers disclosed in these publications are produced by the direct spinning method, the finer the single yarn fineness is, the more fluff and yarn breakage occurs in the yarn making process and the weaving process. In addition, weaving of fabrics for industrial materials is carried out under the condition of no twist and no glue as seen in air bag base fabrics, so that fluff and yarn breakage are likely to occur. With filament filaments, fluff and yarn breakage during weaving are extremely likely to occur such that single yarn breakage occurs during weaving even without fluff during winding. Therefore, with the conventional techniques described in these publications, it is difficult to industrially manufacture an air bag base fabric made of ultrafine fibers having a single yarn of less than 0.8 d from the viewpoint of yarn forming property and weaving property.

Further, Japanese Unexamined Patent Publication (Kokai) No. 1-122752 describes a method of shrink-processing a high-density fabric, heat-fixing it, and calendering it to obtain a base fabric for an airbag having excellent dimensional stability. Has been done. However, also in the present invention, the single yarn fineness of the fibers used is as large as 1d or more, and the flexibility of the fabric is not sufficiently improved even by calendering.

Further, Japanese Patent Laid-Open No. 4-2835 discloses that
A non-coating type airbag base fabric made of polyethylene terephthalate, which is lightweight and thin, and has an air permeability of 0.5 cc / sec / cm ² or less and 650 psi.
Burst strength above, tensile strength above 300 pounds, 40
Woven fabrics having a trapezoidal piece tear strength of over a pound have been proposed. However, the single yarn fineness of the fiber used here is about 1d even if it is thin, and since the above-mentioned calendering is required to suppress the gas permeability, the same problems as described above occur. there were.

Furthermore, it has been attempted to use ultrafine fibers having a single yarn fineness of 1d or less, which has been used for clothing (Japanese Patent Laid-Open No. 5-213131). However, ultrafine fibers for clothing applications are manufactured using a polymer with an intrinsic viscosity of about 0.6 to 0.7 and have a low strength of 2.5 to 4.5 g / d or less, so that they have sufficient strength characteristics for airbags. Was hard to get. Therefore, it has been proposed to combine a high-strength yarn with a normal fineness to compensate for the lack of strength, but in this case, there is a problem that the original characteristics of the ultrafine fiber cannot be sufficiently exhibited due to the combined use of the reinforcing fibers with a large fineness. there were.

Further, Japanese Utility Model Laid-Open No. 56-56500 proposes to use ultrafine fibers for the development fabric of parachute, but even in this case, it is not disclosed to use ultrafine fibers and high strength. .

As is clear from the above examples of the base fabric for airbags and the like, in the field of industrial materials so far, a fiber having a single yarn fineness of 0.8 d or less and having a very high strength. There was no attempt to manufacture and use this.

[0020]

As described above, the conventional fiber structure for industrial materials has excellent mechanical strength and excellent flexibility, and further has low air permeability as necessary, and High-quality fiber structures with little fluff have not yet been obtained.

Therefore, the main object of the present invention is to solve the above-mentioned problems in the prior art and to have excellent mechanical properties and excellent flexibility as a fiber structure used for industrial materials. In the case of a woven fabric with a small amount of fluff, if necessary, to provide a fiber structure having a low gas permeability, and further, generation of fluff or yarn breakage in the fiber structure manufacturing process such as during yarn making or weaving. It is an object of the present invention to provide a method capable of producing the fiber structure at least.

[0022]

In order to achieve the above-mentioned object, the fiber structure of the present invention comprises ultrafine fibers having a single yarn fineness of less than 0.8d and a tensile strength of 6.5g / d.
The above is a high-strength ultrafine fiber structure composed of high-strength multifilaments having a breaking elongation of 15% or more.

In the high-strength ultrafine fiber structure of the present invention, the high-strength multifilament is preferably a polyester fiber, and particularly preferably a polyethylene terephthalate fiber having an intrinsic viscosity (IV) of 0.8 or more.

The high-strength ultrafine fiber structure of the present invention is preferably made of polyamide fiber having a polymerization degree of sulfuric acid relative viscosity (ηrn) of 3.0 or more.

The method for producing a high-strength ultrafine fiber structure of the present invention is a single yarn fineness of 3.0d having a sea-island cross section, which is obtained by simultaneously discharging two components of polymer through a single hole of a die. The number of filaments is 120
It can be manufactured by knitting and weaving with the following substantially non-twisted and non-paste yarns, and then removing the sea component polymer to make the filaments constituting the woven or knitted fabric have a single yarn fineness of less than 0.8d. .

The most important feature of the present invention is that the filaments constituting the fiber structure are high-strength ultrafine fibers which can be easily produced by the method of composite spinning-elution removal, and have a specific tensile strength, elongation at break, The point is that it consists of an ultrafine fiber yarn having a single yarn fineness. As a result, it is possible to obtain a high-quality fiber structure having excellent mechanical properties and excellent flexibility, less fluffing and yarn breakage during its production.
Particularly in the case of a fabric, by setting the number of warp yarns and / or weft yarns set to a specific value, it is possible to obtain a fiber structure having both the above characteristics and low gas permeability.

The fibrous structure in the present invention refers to a part or all of which is composed of a fibrous substance. The fibrous substance here means a substance having a height (aspect ratio) with respect to its diameter of 10 or more when the shape of the substance is approximate to a cylinder. As typical examples of the fiber structure, fabrics such as woven fabric, knitted fabric, and non-woven fabric,
Threads such as ropes and sewing threads are included. In the fibrous structure, the fibrous substance used is preferably present continuously, but may be discontinuous. Further, these cloths and ropes may be used as a composite material in which a resin is impregnated or coated, or may be a three-dimensional material in which a fibrous substance is contained as a reinforcing material inside or on the surface of the resin. Good.
Thus, the high-strength ultrafine fiber structure in the present invention is a fiber structure in which the high-strength ultrafine fiber described in the present invention is used at least in part.

The fiber structure using the high-strength ultrafine fibers in the present invention is a one-dimensional structure such as a rope and a woven fabric,
Although it is represented by a two-dimensional structure as a cloth such as a knit or a non-woven fabric, it may be a three-dimensional structure such as a resin composite used as a reinforcing material of another resin, and may be used in any form without particular limitation. However, in order to further exert the effects of flexibility, lightness, and texture which are the characteristics of the ultrafine fibers, the form of the cloth, which is a two-dimensional fiber structure, is preferable.

In the multifilament constituting the high-strength ultrafine fiber structure of the present invention, the fineness of the single yarn constituting the multifilament must be less than 0.8d.

When the single yarn fineness is 0.8 d or more, the flexibility of the fiber structure cannot be sufficiently improved even if the total fineness is suppressed. On the other hand, if the single yarn fineness is too thin, it is necessary to considerably increase the number of filaments in order to obtain the strength required for industrial material applications, and even if the composite spinning method is used, a composite yarn is required. It lacks practicability in industrial practice and causes problems in quality. From this point, it is more preferably 0.1 d or more and less than 0.8 d, and even more preferably 0.1 d or more and 0.5 d or less.

Further, the multifilament constituting the high-strength ultrafine fiber structure in the present invention needs to have a tensile strength of 6.5 g / d or more, and particularly preferably 7.5 g / d or more. The above-mentioned strength characteristics are required to satisfy the mechanical characteristics required as a high-strength ultrafine fiber structure, and if it is lower than the above values, it is difficult to satisfy the mechanical characteristics required for practical use. By constructing the fiber structure from such high-strength ultrafine fibers, in the present invention, necessary mechanical properties and the like can be provided without using fibers having a large single yarn fineness.

The multifilament constituting the high-strength ultrafine fiber structure of the present invention has a breaking elongation of 15%.
The above is required, and 18% or more is particularly preferable. When the elongation at break is less than 15%, even if the fineness of the single yarn is less than 0.8d, it is hard and inferior in flexibility when formed into a fiber structure, and further, fluff or yarn breakage occurs during spinning or weaving. Is likely to occur and is inappropriate. When the breaking elongation is too high, the elongation of the fiber structure itself becomes too large, which is not preferable in terms of dimensional stability and shape maintenance, and is usually preferably 40% or less. When the fiber structure is a base fabric for an airbag as described below, it is not preferable from the viewpoint of suppressing gas permeability when the breaking elongation exceeds 40%.

The above-mentioned tensile strength and elongation at break in the present invention are values when they are present as constituent members in the fiber structure, and are values at the stage of the raw yarn before forming the structure. Absent. That is, it is a value after forming the ultrafine fibers, and is not a value for the composite yarn subjected to the sea removal treatment. From the viewpoint of efficiency, it is preferable that the step of removing the seawater from the composite fibers to obtain ultrafine fibers is performed after forming the fiber structure, and is performed by solvent treatment, dissolution treatment, or the like as described later. The fibers are slightly shrunk by the ultrathinning treatment at this time, and as a result, the elongation is slightly higher than that before the ultrathinning.

The multifilament polymer constituting the high-strength ultrafine fiber structure in the present invention is not particularly limited as long as the ultrafine fibers can be finally produced by the known sea-island type, and the known polymer for synthetic fiber is used. Is applicable. Examples of representative polymers include polyethylene terephthalate, polybutylene terephthalate, polyesters represented by polyethylene naphthalate, polyhexamethylene adipamide, polytetramethylene adipamide, polyamides represented by polycapramide, polyacrylonitrile, polyvinyl. Examples thereof include alcohols, polyolefins such as polyethylene and polypropylene, aromatic polyamides, aromatic polyesters, and the like.

The polymer used may contain other copolymerization components or additives for the purpose of enhancing the spinnability, etc., as long as they do not impair their original excellent properties. In addition, additives such as a light resistance agent, an antioxidant, and a pigment may be included for the purpose of enhancing the performance of the fabric as long as the spinnability is not impaired.

Filaments made of polyester or polyamide are preferred in consideration of the ease of producing ultrafine fibers by the composite spinning method, the dimensional stability of the obtained fiber structure, the mechanical properties and the like. Among them, polyethylene terephthalate fibers in which 85% by weight or more is composed of ethylene terephthalate units are particularly preferable.

When the ultrafine fibers are polyethylene terephthalate fibers, the use of a high-viscosity polymer makes it easy to obtain the above-mentioned strength and elongation. Therefore, the ultrafine fibers finally obtained have an intrinsic viscosity of 0.8 or more. Is preferred. If the obtained ultrafine fibers have an intrinsic viscosity of less than 0.8, it is difficult to obtain the desired strength and elongation, and the heat resistance and the dimensional stability are also lowered, which is not preferable.

Further, in the high-strength ultrafine fiber structure of the present invention, when the ultrafine fibers constituting this fiber structure are polyethylene terephthalate fibers, the crystal volume value (C) measured by wide-angle X-ray is 8 × 10 ⁴ (angstrom). ) ³
As described above, the long period in the meridional direction (D
It is preferable that m) is 120 Å or more and the crystal orientation degree (Fc) calculated by wide-angle X-ray measurement is 0.90 or more. When the crystal volume value (C) is less than 8 × 10 ⁴ (angstrom) ³ , the long period (Dm) is less than 120 angstrom, or the crystal orientation degree (Fc) is less than 0.90, high strength can be obtained. It is difficult to be treated, and hydrolysis tends to occur, resulting in poor durability.

Further, in the high-strength ultrafine fiber structure of the present invention, when the ultrafine fibers constituting this fiber structure are polyethylene terephthalate fibers, the degree of amorphous orientation (Fb) is preferably 0.975 or more. Amorphous orientation (F
When b) is less than 0.975, dimensional stability and heat resistance are insufficient, and it tends to be difficult to use it as an industrial material.

On the other hand, in the high-strength ultrafine fiber structure of the present invention, when the ultrafine fibers constituting this fiber structure are polyamide fibers such as polyhexamethylene adipamide and polycapramide, the polyamide fiber has a low initial modulus. Therefore, the flexibility of the fiber structure is synergistically exerted with the effect of the ultrafine fibers and is effectively exhibited, which is preferable. Even in this case, if a high-viscosity polymer is used, the above-mentioned strength and elongation are easily obtained, and it is desirable that the 98% sulfuric acid relative viscosity (ηrn) of the ultrafine fibers finally formed is 3.0 or more.

In the high-strength ultrafine fiber structure of the present invention, all the ultrafine yarns constituting the high-strength multifilament are substantially the same in that high-strength fibers are easily obtained and spinning is easy. It is preferable that the polymer composition is

In order to make all of the ultrafine yarns constituting the high strength multifilament substantially one kind of polymer composition,
In addition to direct spinning, composite spinning methods such as sea-island composite spinning,
There is a method in which only one kind of polymer is finally left by using a blended spinning method or the like to form an ultrafine fiber multifilament. It is more preferable to use the sea-island type composite spinning method from the viewpoint of ease of production, and then to obtain ultrafine fibers by de-sealing treatment. Further, this sea-island type composite spinning method is particularly preferable when the total fineness of the target high-strength ultrafine multifilament is large, or when the single-filament fineness of the ultrafine fiber is lower.

Further, when the fiber structure using the high-strength ultrafine fibers in the present invention is a cloth, in order to exert the effects of the flexibility, the lightness and the texture which are the characteristics of the ultrafine fibers, the multi to be used is used. The total fineness of filament is 1000
It is preferably d or less. Furthermore, considering the strength level required for industrial materials, etc., 100 to 10
00d is more preferable. In the case of a multifilament having a fineness of more than 1000 d, even the ultrafine fibers having a single yarn fineness of less than 0.8 d have a too large thickness of the fabric, and it is difficult to sufficiently exhibit flexibility and flexibility.

The fabric thus obtained generally has a tensile strength of 100 kg / 3, although it depends on its weaving density.
It is possible to have excellent properties such as cm or more, preferably 150 kg / 3 cm or more, more preferably 170 kg / 3 cm or more, and the flexibility evaluation by the cantilever method of 60 mm or less, more preferably 45 mm or less. If the tensile strength is less than 100 kg / 3 cm, the mechanical strength may be insufficient for industrial material applications, and if the flexibility evaluation is greater than 60 mm, the flexibility improving effect aimed at by the present invention may be insufficient. There is not preferable.

The fabric using the high-strength ultrafine fibers of the present invention can be applied to various industrial materials, but among them, it is excellent in flexibility and lightness, and further, it is gas by designing the fabric structure. It is suitable to be used as a base fabric for an air bag because the low permeability can be easily obtained.

The properties required of the airbag base fabric include mechanical properties such as tensile strength, tear strength and burst strength as a fabric, as well as flexibility, light weight, compactness during storage (foldability), Examples include low gas permeability. To make an airbag base fabric that satisfies these requirements,
The total fineness of the high-strength ultrafine fiber filaments constituting it is preferably 180 to 450 d. Total fineness is 45
If it exceeds 0d, the fabric thickness becomes too thick when the fabric is made to have a high density so that a sufficiently low air permeability level can be obtained without resin coating (hereinafter, abbreviated as non-coated product), and the flexibility and lightness are reduced. It is not preferable because it is easily damaged. Furthermore, the compactness tends to be poor when stored. On the other hand, if the total fineness is less than 180 d, the mechanical strength of the fabric tends to be insufficient and the fabric tends to burst at the time of expansion no matter how densely woven it is, which is not preferable. Furthermore, the preferable total fineness is 200 to 375 d.

Further, the cover factor K of the cloth is set to 1900.
As described above, more preferably 2000 or more, it is possible to obtain an excellent airbag base fabric even without coating. If the cover factor K is less than 1900, the non-coating has too high air permeability, which makes it difficult to achieve satisfactory expansion, and further, the mechanical strength of the fabric tends to be weak, which is not preferable.

The obtained air bag base fabric has a tensile strength of 100 kg / 3 cm or more as a base fabric, a flexibility evaluation by the cantilever method of 60 mm or less, and a gas permeation amount of 5.0 cc at a pressure drop of 1.27 cm. It is possible to have excellent characteristics such as / sec / cm ² or less, and it has low air permeability and flexibility.

A base cloth satisfying such conditions is
Tear strength as high as 8 kgf or more (JIS-L-1
096 (trapezoid method), and has a high burst strength (according to JIS-L-1018A method (Mullen method)) of 40 kg / cm ² or more) It is also possible.

As described above, according to the present invention, the warp yarn and the weft yarn constituting the airbag base fabric are high-strength ultrafine fibers which can be easily produced by the method of composite spinning-eluting removal, and have a specific tensile strength, By using an ultrafine fiber yarn having break elongation, total fineness, and single yarn fineness, not only excellent mechanical properties but also low gas permeability and excellent flexibility, and fluff during weaving or It is possible to obtain a high-quality airbag base fabric with less yarn breakage. Of course, this airbag base fabric can be used as a non-coated product without resin coating, or may be resin-coated and used as the case requires.

The high-strength ultrafine fiber structure according to the present invention is
As described above, it is preferable that it is composed of high-strength ultrafine fibers obtained by using the sea-island type composite spinning method. For example, it can be easily produced by the following method.

First, by the usual sea-island type composite spinning method in which the two components of the polymer are simultaneously discharged through a single hole of the spinneret,
A multi-filament yarn having a sea-island structure and a single fiber fineness of 3.0 d or more is produced.

The island component is a polymer that finally constitutes the fabric, and the sea component is a polymer having a higher solubility in a specific solvent than the island component. put it here,
The island component needs to have the above-mentioned high elongation to obtain a filament having sufficient mechanical properties, and for that purpose, it is preferable to use a polymer having a high degree of polymerization.
Specifically, in the case of polyethylene terephthalate, the intrinsic viscosity (IV) in the state of ultrafine fibers is 0.8 or more, and in the case of polyamide, 98% in the state of ultrafine fibers.
Since the sulfuric acid relative viscosity (ηrn) is preferably 3.0 or more, the viscosity of the chips to be spun is 1.0 or more in intrinsic viscosity (IV) in the case of polyethylene terephthalate, and in the case of polyhexamethylene adipamide. , 98% sulfuric acid relative viscosity (ηrn) of 3.0 or more is used,
It is preferable in order to obtain the above-mentioned strong elongation property.

The smaller the proportion of the sea component to be removed, the higher the productivity becomes, and it is easy to obtain a fiber structure having a higher density and more suppressed gas permeability. From these points, the sea component ratio should be as low as possible. Are generally preferred. Therefore,
Sea component is preferably 20% or less, more preferably 10%
It is the following. However, if the sea component ratio is too low, the island components are likely to merge with each other, and the smooth drawing of the composite fiber, particularly the difficulty of drawing at a high magnification, increases and the mechanical properties of the filament are increased. Since it may be difficult to obtain a high elongation, it is preferable that the strength be at least about 5%.

The polymer of island component and sea component forms a composite flow having a sea-island structure in cross section in the spinneret, and is spun from the spinneret by a usual melt spinning method. At this time, in order to prevent the polymer from deteriorating due to heat, the shorter the residence time of the polymer in the spinning machine is, the more preferable it is.
~ 5 minutes is preferred.

When the two polymers were discharged from the spinneret, the number of filaments of the composite yarn per spinneret was 120.
The following is preferable, and 20 to 90 is more preferable. 120
In general, the hole spacing on the spinneret surface, which has a limited area, becomes narrower, the composite single yarns in the yarns tend to collide with each other after ejection, and stable spinning becomes difficult. Due to the cross-sectional structure, bending of the discharge polymer on the spinneret surface is likely to occur, and collision between single yarns in the yarn is likely to occur, which is not preferable.

In the sea-island type spinning method, the number of filaments of the composite yarn and the number of island components in one composite yarn may be determined depending on the total fineness and the single yarn fineness of the ultrafine fiber multifilaments to be obtained. If the number of filaments in the composite yarn is too small, the number of islands will generally be too large, and the individual yarn fineness of the composite yarn will be considerably large, resulting in uneven cooling of the yarn and impairing the spinning stability. It is not preferable because it is easy. On the contrary, when the number of filaments of the composite yarn is too large, the number of islands contained in one composite yarn becomes too small, and the composite yarn 1
Since the fineness of the book becomes too thin, collision between single yarns is likely to occur during spinning cooling, and fuzz and yarn breakage are likely to occur, which is not preferable. Usually, the number of filaments and the number of islands of the composite yarn are preferably designed in a balanced manner so that the single yarn fineness of the composite yarn falls within the range of 3 to 10 d in the drawn yarn.

Immediately below the spinneret, a heating cylinder having a length of 10 to 100 cm and a temperature controlled at 200 to 350 ° C. is provided.
The discharged yarn is preferably passed through the high temperature atmosphere in the heating cylinder. The length and temperature conditions of the heating cylinder may be optimized depending on the two types of polymer characteristics, yarn fineness, and the number of filaments of the composite fiber. This heating cylinder is effective for delaying the solidification of the molten polymer and developing high strength. The atmosphere in the heating cylinder may be sealed with a high temperature inert gas, if necessary, for the purpose of preventing thermal deterioration at high temperatures.

The spun yarn, after passing through a high temperature atmosphere,
It is cooled and solidified with cooling air, and then an oil agent is applied, and then it is taken up by a take-up roll that controls the spinning speed.

The undrawn yarn taken up by the take-up roll is preferably continuously drawn without being taken up, but may be taken up once and drawn in a separate step. The spinning speed is
Usually, it is preferably performed at 1500 m / min or less. Stretching may be performed by an ordinary hot stretching method, and multistage stretching of two or more stages is preferable. The draw ratio may be appropriately optimized depending on the type of polymer, the spinning speed, and the like, and can be changed depending on the birefringence in the undrawn yarn stage, the drawing temperature, the draw ratio distribution in multistage drawing, and the like. 0 times or more, preferably 3.
It may be 0 to 6.5 times, more preferably 4.0 to 6.0 times.

The yarn of the composite fiber obtained by drawing in this manner preferably has a single yarn fineness of 3d or more and further 5d or more. 3d
When it is less than, if the fineness is likely to occur due to yarn wobbling in the heating cylinder during spinning, and uniform stretching becomes difficult,
Furthermore, it is not preferable because it easily causes yarn breakage or fuzz.

Next, the drawn yarn is heat set. The heat fixation may be carried out by a usual method such as a method of bringing the yarn into contact with a heat roller or a hot plate, or a method of passing through a high temperature gas. The dry heat shrinkage can be adjusted by changing the tension and temperature during the heat setting. For example,
When imparting low air permeability to the fiber structure, 150
The dry heat shrinkage rate during heat treatment at 30 ° C. for 30 minutes is preferably 1 to 10%, more preferably 3 to 8%. When the sea component is removed in the state of the cloth, the cloth shrinks moderately and is removed. A low gas permeability is achieved after the sea. The optimum dry heat shrinkage is
It may be determined from the weaving density conditions during weaving, the desired air permeability of the fabric, the level of mechanical strength, and the like.

In the high-strength ultrafine fibers produced by the sea-island type composite spinning method of the present invention, the filaments may be entangled in the drawing step and the heat setting step in order to further suppress the occurrence of fluff. A known method such as air entanglement may be adopted for the entanglement processing. For example, in the case of air entanglement, the desired entanglement degree can be obtained by appropriately changing the air pressure according to the yarn fineness and the tension. In this case, the degree of entanglement is preferably 20 or more, more preferably 50 or more.

The yarn of the composite fiber obtained by drawing usually has a single yarn fineness of 3 to 8 d, a tensile strength of 7.0 g / d or more, further 8.0 g / d or more, and a breaking elongation of 13. A multi-composite filament yarn having a content of 5% or more may be used.

In order to produce a high-strength ultrafine fiber structure using this multi-composite filament, first, the obtained multi-composite filament is used as it is to prepare a fiber structure. For example, when the fibrous structure is a woven fabric, the multi-composite filament may be used for the warp and the weft and woven by a usual method. The weaving is usually performed without twisting and without sizing, but may be twisted or sizing as necessary. The woven structure is
A plain weave or a diagonal weave can be selected according to the purpose. Weaving conditions such as weaving density may be determined according to the purpose. Especially when it is used as a base fabric for airbags, the filament fineness, the amount of sea component removed and the degree of shrinkage in the sea removal treatment process are taken into consideration so that the final cover factor (K) of the fabric will be a predetermined value. Then, weaving conditions can be designed.

In the composite spinning method of the present invention, finally, a fiber structure composed of ultrafine filaments having a very fine single yarn fineness of less than 0.8 d is converted into a thick single yarn having a single yarn fineness of 3.0 d or more. After spinning in the state of composite filament yarn,
Since the shape of the target fiber structure is used, and then the fiber is manufactured by the method of making ultrafine fibers, there is sufficient occurrence of yarn breakage and fluff during spinning and fluff and yarn breakage during fiber structure production. Can be suppressed. Therefore, for example, even when the fibrous structure is a woven fabric, it is possible to easily produce a woven fabric in which spinnability and workability are good, and flexibility and lightness are sufficiently improved without performing sizing or twisting during weaving. is there.

Next, the produced fiber structure is subjected to sea removal treatment to remove sea components, thereby forming the filaments constituting the target ultrafine fibers. The sea-removing treatment may be selected according to the characteristics of the polymer for sea components, but for example, treatments such as elution with water, decomposition with various aqueous solutions such as acidic solutions and alkaline solutions, and dissolution with organic solvents are used. In addition, two or more of these treatments may be combined. Furthermore, as described in JP-A-56-118961, the sea component polymer may be subjected to an embrittlement treatment in advance before the desalination treatment.

These treatments may be combined with heating and pressurizing conditions as long as the characteristics of the island components constituting the fiber structure are not impaired. When using the base fabric for airbags,
In order to suppress the gas permeability, it is necessary to shrink the fabric to some extent at the same time as the sea removal treatment to reduce the space where the sea component was present. For this purpose, a method of removing sea components by passing through the solution while heating is preferable, and further, treatment at 70 ° C. or higher is preferable in order to cause shrinkage.

Specific polymers used as the sea component include, for example, polystyrene dissolved in a solvent, polyester copolymerized with 5 sodium isophthalic acid dissolved in water or decomposed in an aqueous solution, and other known polymers. Examples include water-soluble polymers.
An example of a water-soluble polymer that can be eluted with water is diol component containing terephthalic acid as a main acid component, 5-sodium sulfoisophthalic acid 8 to 16 mol% and isophthalic acid 5 to 40 mol%, and ethylene glycol as a main component. And a water-soluble polyester obtained by copolymerizing polyethylene glycol having a molecular weight of 5000 or less in an amount of 10% by weight or less (described in JP-A-4-361659).
The water-eluting type polymer is preferable from the viewpoint of the final mechanical properties, because the damage to the island components during the desalination treatment is small.

The fiber structure obtained through the sea removal step by the above method has an extremely fine single yarn fineness of less than 0.8 d, and has a high tensile strength of 6.5 g / d or more, and further its breakage. It is composed of multifilaments of high-strength ultrafine fibers having an elongation of 15% or more.

According to the production method using sea-island type composite spinning, even if the elongation is about 13% at the stage of the composite fiber yarn, it is highly elongated by the sea removal treatment and has a elongation of 15% or more. It can be a constructed fibrous structure.

From the viewpoint of spinning stability and the like in the case of producing ultrafine fibers using sea-island type composite spinning, the polymer for the island component which constitutes the final ultrafine fibers is preferably made of one kind of polymer material. .

In the fiber structure of the present invention, it is necessary to optimally design the total fineness and single yarn fineness of the ultrafine fiber multifilaments constituting the fiber structure according to its form and use. When the sea-island type composite spinning method is used here, the number of ultrafine filaments produced from one composite yarn, that is, the number of islands, can be made larger than that of the split type composite yarn due to its spinneret structure. is there. In the case of the split type, since the number of divisions cannot be increased so much, it is necessary to make the fineness of one composite yarn considerably thin in order to generate an ultrafine fineness, and the stability of the yarn production is likely to be impaired. Therefore, the sea-island type spinning method is preferable in order to stably obtain sufficiently fine ultrafine fibers.

The fiber structure of the present invention may be subjected to treatment such as calendering or heat setting, if necessary, as long as it does not impair the characteristics of the present invention.

[0075]

The present invention will be described in detail below with reference to examples. Each physical property in the present invention is a value measured as follows.

(1) Intrinsic viscosity (IV) of polyester:
A polymer solution was prepared by dissolving 2 g of the sample polymer in 25 ml of orthochlorophenol, and the relative viscosity ηrp of the polymer solution was measured at 25 ° C. using an Ostwald viscometer, and the intrinsic viscosity (IV) was calculated by the following approximate expression. To do. IV = 0.0242 · ηrp + 0.2634 where ηrp = (t × d) / (t ₀ × d ₀ ) t: Fall time of solution (sec) t ₀ : Fall time of orthochlorophenol (sec) d: Solution Density (g / cc) d ₀ : density of orthochlorophenol (g / cc) (2) Sulfuric acid relative viscosity of polyamide (ηrn): 9 samples
It is dissolved in 8% sulfuric acid at a concentration of 1% by weight and measured at 25 ° C. using an Ostwald viscometer.

(3) Tensile strength and elongation at break of composite fiber yarn: Measured in accordance with JIS-L-1017.

(4) Tensile Strength and Elongation at Break of Multifilament Constituting Fiber Structure: Measured by taking out multifilament from the fiber structure. For example, in the case of a woven fabric, the decomposed yarn from the woven fabric is used, and in the case of a knitted fabric or the like, a filament extracted from these without damaging the yarn is used as a sample. A load of about ⅓ of the fineness of the original yarn stage is applied to this sample, and the sample is cut into a length of 25 cm. The weight is measured, and the decomposed yarn fineness is calculated by converting the weight to a length of 9000 m. Next, using an RTM-100 tensile tester manufactured by Orientec, a test length of 15
The tensile test is performed under the conditions of cm and a tensile speed of 30 mm / min. The strength at the maximum strength point is read from the obtained load-elongation curve, and the value obtained by dividing this value by the decomposed yarn fineness is taken as the tensile strength of the decomposed yarn. Also, the cutting elongation is read from the load-elongation curve.

(5) Fiber crystal volume value (C) Wide-angle X-ray generator (4036A2 type) manufactured by Rigaku Denki Co., Ltd.
Is used to measure CuKα (using a Ni filter) as a radiation source. (Output 35KV, 15mA, slit 2mm
φ). The shooting conditions are equatorial direction 2θ = 10 to 35 °, meridian direction 2θ = 10 to 35 °, and circumferential direction 2θ = 90 to 270.
The step may be 0.05 ° (0.5 ° in the circumferential direction) and the integration time may be 2 seconds.

The crystal size is calculated from the half width of the peaks of the plane indices (010), (100) and (-105) obtained by the transmission method, using the Scherrer's formula below. ◎ L (hkl) = Kλ / β ₀ cos θ _B where L (hkl) is the average size of the crystallites in the direction perpendicular to the (hkl) plane, K: 1.0, λ is the wavelength of X-rays, β ₀ : (β _E ² −β _I ² ) ^1/2 , β _E : apparent half width (measured value) β _I : 1.05 × 10 ⁻² rad β _B : Bragg angle. The crystal volume value (C) is calculated from the value of the crystal size on each surface obtained by the above method by the following equation. V = L (010) x L (100) x L (-105) ((angstrom) ³ ) (6) Long period in the meridional direction of fiber (Dm) Small angle X-ray generator (RU200 type) manufactured by Rigaku Denki Co., Ltd. ) Is used to measure CuKα (using a Ni filter) as a radiation source. (Output 50KV, 200mA, slit 1mm
φ). Shooting conditions: camera radius 400 mm, film K
odak DEF-5, exposure time 120 minutes. From the distance (r) on the small-angle X-ray scattering photograph, the following Br
The long period (J) is calculated using the agg equation.

J = λ / 2Sin [{tan ⁻¹ (r / R)}}] where R is the camera radius, λ is the wavelength of X-rays, and J is the long period. Since the high-strength ultrafine fibers of the present invention exhibit layered four-point scattering, LEAlex-ander's translation by Sakurada, Hamada, Kajii, “Polymer X-ray (below)”, Chapter 5, Kagaku Dojin (197)
According to the definition of 3), the long period (Dm) (angstrom) can be calculated from the spot distance corresponding to the fiber axis direction.

(7) Crystal orientation of fiber (Fc) From the half width (H °) of the intensity distribution curve along the Debye ring of the equatorial line interference of the (010) plane obtained in the wide angle X-ray measurement described above. The crystal orientation degree (Fc) is calculated by the following formula. Fc = (180 ° -H °) / 180 ° (8) Amorphous orientation degree (Fb) of fiber Measured by a polarized fluorescence method. The instrument used was FOM-1 manufactured by JASCO Corporation, and the transmission method (excitation light wavelength: 365) was used.
nm, fluorescence wavelength: 420 nm). The sample yarn was used by being immersed in an aqueous solution containing about 0.2% of a fluorescent agent at 55 ° C. for 4 hours, washed with water and air-dried.

(9) Tensile Strength of Cloth Measured with a sample width of 3 cm according to JIS-K-6328 (strip method). The results are shown by the average value of the warp direction value and the weft direction value of the fabric.

(10) Softness of Cloth This is represented by the bending resistance measured by JIS-L-1096 (45 ° cantilever method).

(11) Gas permeation amount of fabric (gas permeation amount when pressure drop of water column is 1.27 cm) Measured according to JIS-L-1096 (method A), air amount passing through is cc / sec / cm Shown with ² .

(12) Process Passability The process passability (passability due to fluff and yarn breakage) during the production of the fiber structure was relatively evaluated.

[Example 1] Polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 1.20 was used as the polymer for the island component, and 5.0% mol of 5-sodium sulfoisophthalic acid was used as the polymer for the sea component. Polymerized polyethylene terephthalate (intrinsic viscosity IV = 0.70) (Co
-PET) was used to perform a two-component melt composite spinning by a usual sea-island composite spinning method. The spinneret has 60 holes, the number of islands in one composite fiber is 16, and the sea-island ratio is island / sea = 91/9
And The spinning temperature at this time was 290 ° C., a heating cylinder having a length of 300 mm and a temperature of 320 ° C. was arranged immediately below the spinneret, and the spinning speed was 600 m / min.

Then, the composite spun yarn was continuously drawn by a two-stage drawing without winding, and a draw ratio was set to 5.5 at a total draw ratio of 215 ° C. and a final draw roll temperature of 215 ° C., and then 3.0.
Relaxed at a relaxation rate of%, total fineness 335d,
It was a sea-island type composite fiber yarn of 60 filaments. During spinning and drawing, there is no noticeable yarn breakage or fluff,
Stable spinning was possible.

The obtained composite fiber yarn had a single yarn fineness of 5.58 d, a strength of 8.6 g / d and an elongation of 14.8.
%Met. When the sea component of this fiber was dyed with a cationic dye and then the cross section of the fiber was observed with a scanning electron microscope, it was confirmed that a beautiful sea-island structure was formed.

Next, this composite fiber yarn was used as a warp yarn and a weft yarn to prepare a plain weave having a weave density of 62 warps / inch and 61 wefts / inch. This weaving was performed with no paste and no twist, but fluff and yarn breakage were hardly generated during the process.

Next, this woven fabric was treated with a 1% sulfuric acid boiling aqueous solution for 60 minutes in a relaxed state, and then passed through an aqueous sodium hydroxide solution at 90 ° C. to remove sea components (5-sodium sulfoisophthalic acid copolymerized polyester). . Then
This woven fabric was dried and heat set by a conventional method to obtain a base fabric for an airbag.

The filaments constituting the obtained woven fabric were obtained by finely dividing the composite fibers, and the decomposed yarns of this woven fabric had a total fineness of 310d, a number of filaments of 960, and a single yarn fineness of 0.32d. Strength 7.6 g / d, elongation 19.
It was 5%. The woven density of the woven fabric after heat setting was 63 warps / inch, 61 wefts / inch, and the cover factor was 2183.

[Example 2] A two-component melt composite spinning and drawing were carried out in the same manner as in Example 1 except that the total polymer discharge amount was changed and the air entanglement was performed immediately before winding the drawn yarn to obtain the total fineness. A drawn yarn of sea-island type composite fiber of 235d and 60 filaments was obtained. The sea-island ratio at this time was island / sea = 90/10.

The obtained composite fiber yarn had a single yarn fineness of 3.92.
d, strength was 8.5 g / d, elongation was 16.7%, and degree of entanglement was 60.

Next, this composite fiber yarn was used as a warp yarn and a weft yarn to prepare a plain weave having a weaving density of 71 warps / inch and 70 wefts / inch. This weaving was performed with no paste and no twist, but fluff and yarn breakage were hardly generated during the process.

Then, in the same manner as in Example 1, the woven fabric was treated in a relaxed state with a 1% aqueous solution of boiling sulfuric acid, and then 8
It was passed through a 0 ° C. aqueous sodium hydroxide solution to remove sea components. Next, this woven fabric was dried and heat set by a conventional method to obtain a base fabric for an airbag.

The filaments constituting the obtained woven fabric were obtained by finely dividing the composite fiber, and the decomposed yarn of this woven fabric had a total fineness of 222d, the number of filaments of 960, and a single yarn fineness of 0.23d. Strength 7.4 g / d, elongation 20.
It was 0%. The woven density of the woven fabric after heat setting was 73 warps / inch, 72 wefts / inch, and the cover factor was 2160.

[Example 3] A two-component melt composite was performed in the same manner as in Example 1 except that a spinneret having 90 holes, 12 islands in one composite fiber was used, and the total discharge amount was changed. Spin and draw to obtain a total fineness of 855d, 90
A sea-island composite drawn yarn of filament was obtained. The sea-island ratio at this time was island / sea = 87/13.

The obtained composite fiber yarn had a single yarn fineness of 9.50.
d, the strength was 8.9 g / d, and the elongation was 16.5%.

Next, this composite fiber yarn was used as a warp yarn and a weft yarn to prepare a plain weave having warp density of 28 warps / inch and 28 wefts / inch. This weaving was performed without sizing and twisting, but fluff and yarn breakage were hardly generated during the process.

Then, treatment with a boiling sulfuric acid aqueous solution and treatment with a sodium hydroxide aqueous solution were carried out under the same conditions as in Example 2 to remove sea components, followed by drying and heat setting.

The filaments constituting the obtained woven fabric were obtained by finely dividing the composite fiber, and the decomposed yarn of this woven fabric had a total fineness of 774d, a number of filaments of 1080, and a single yarn fineness of 0.73d. Strength 7.4g / d, elongation 2
It was 1.2%. The woven density of the woven fabric after heat setting was 30 warps / inch, weft 29 threads / inch, and the cover factor was 1641.

Example 4 The polymer for the island component was polyhexamethylene adipamide (N66) having a 98% sulfuric acid relative viscosity (ηrn) of 3.2, and the sea-island ratio was island / sea = 90/10.
In the same manner as in Example 1 except that the spinning speed was 700 m / min and the total amount of polymer discharged was changed, a two-component melt composite spinning was performed.

Then, the composite spun yarn was continuously drawn in two steps without winding, and drawn and heat-treated at a final draw roll temperature of 215 ° C. with a total draw ratio of 5.0 times, and then 3.0.
The relaxation treatment was performed at a relaxation rate of%, and then the air entanglement treatment was performed to obtain a sea-island type composite fiber yarn having a total fineness of 345 d, 60 filaments, and an interlacing degree of 50. During spinning and drawing, there was no noticeable yarn breakage or fluff, and stable spinning was possible.

The obtained composite fiber yarn had a single yarn fineness of 5.75 d, a strength of 8.8 g / d and an elongation of 21.5.
%Met. When the sea component of this fiber was dyed with a cationic dye and then the cross section of the fiber was observed with a scanning electron microscope, it was confirmed that a beautiful sea-island structure was formed.

Next, this composite fiber yarn was used as a warp yarn and a weft yarn to prepare a plain weave having a weaving density of 60 warps / inch and 59 wefts / inch. This weaving was performed with no paste and no twist, but fluff and yarn breakage were hardly generated during the process.

Next, this woven fabric was passed through an aqueous sodium hydroxide solution at 95 ° C. in a relaxed state to remove the sea component (5-sodium sulfoisophthalic acid copolymerized polyester). Next, this woven fabric was dried and heat set by a conventional method to obtain a base fabric for an airbag.

The filaments constituting the obtained woven fabric were obtained by finely dividing the composite fiber, and the decomposed yarn of this woven fabric had a total fineness of 330d, the number of filaments of 960, and a single yarn fineness of 0.34d. Strength 8.2g / d, elongation 24.
It was 5%. The woven density of the woven fabric after heat setting was 62 warps / inch, 61 wefts / inch, and the cover factor was 2234.

[Comparative Example 1] The number of islands in one composite fiber was 6
Then, two-component melt composite spinning was performed in the same manner as in Example 1 except that the total polymer discharge amount was changed.

Next, this composite spun yarn was drawn in the same manner as in Example 1 to obtain a sea-island type composite drawn yarn having a total fineness of 340d and 60 filaments. In spinning and drawing, there was no noticeable yarn breakage or fluff, and stable spinning was possible.

The obtained composite fiber yarn had a single fiber fineness of 5.67d, a strength of 8.6g / d and an elongation of 17.5%.

Next, this composite fiber yarn was used as a warp yarn and a weft yarn to produce a plain weave having a weave density of 57 warps / inch and 56 wefts / inch. This weaving was performed with no paste and no twist, but fluff yarn breakage hardly occurred during the process.

Then, in the same manner as in Example 1, the sea component was removed, drying and heat setting were carried out to obtain a base fabric for an airbag.

The filaments constituting the obtained woven fabric were obtained by finely dividing the composite fiber, and the decomposed yarn of this woven fabric had a total fineness of 320d, a number of filaments of 360, and a single yarn fineness of 0.89d. Strength 7.6 g / d, elongation 19.
It was 4%. The woven density of the woven fabric after heat setting was 58 warps / inch, weft 57 threads / inch, and the cover factor was 2058.

[Comparative Example 2] Polyethylene terephthalate having an intrinsic viscosity (IV) of 0.70 was used as the polymer for the island component, the spinning temperature was set to 280 ° C, the total discharge amount of the polymer was changed, and the heating cylinder immediately below the spinneret was used. A two-component sea-island composite spinning was performed in the same manner as in Example 1 except that it was not used.

Next, the composite spun yarn was continuously drawn by one-step drawing without winding up, at a draw ratio of 3.3 times, and then subjected to a relaxation treatment at a relaxation rate of 3.0% to obtain a total fineness of 235d, 60. It was a sea-island type composite drawn yarn of filament. In spinning and drawing, stable spinning was possible without noticeable yarn breakage or generation of fluff.

The obtained composite fiber yarn had a single fiber fineness of the composite fiber of 3.92 d, a strength of 3.9 g / d and an elongation of 24.0%. When the sea component of this fiber was dyed with a cationic dye and the cross section of the fiber was observed with a scanning electron microscope, it was confirmed that a beautiful sea-island structure was formed.

Next, this composite fiber yarn was used as a warp yarn and a weft yarn to prepare a plain weave having a weaving density of 71 warps / inch and 70 wefts / inch. This weaving was performed without sizing and twisting, but fluff and yarn breakage were hardly generated during the process.

Then, this woven fabric was passed through a boiling sulfuric acid aqueous solution in a relaxed state and then passed through a sodium hydroxide aqueous solution at 80 ° C. to remove the sea component (5-sodium sulfoisophthalic acid copolymerized polyester). Then, this woven fabric was dried and heat set by a conventional method to obtain a base fabric for an airbag.

The filaments constituting the obtained woven fabric were obtained by finely dividing the composite fiber, and the decomposed yarns of this woven fabric had a total fineness of 222d, a number of filaments of 960, and a single yarn fineness of 0.23d. Strength 3.4 g / d, elongation 27.
It was 2%. The weaving density of the woven fabric after heat setting was 73 warps / inch, weft 73 threads / inch, and the cover factor was 2175.

[Comparative Example 3] Comparative Example 2 except that the weaving density when producing a woven fabric was 52 warps / inch and weft 52 threads / inch.
Weaving was carried out in the same manner as above, deseaing treatment, drying and heat setting were carried out to obtain an air bag base fabric. The woven density of the obtained woven fabric after heat setting was 53 warps / inch, weft 53 threads / inch, and the cover factor was 1579.

[Comparative Example 4] Intrinsic viscosity (IV) was 1.20.
The polyethylene terephthalate of Example 1 was spun by a normal melt spinning method by a direct spinning method using a spinneret having 60 holes. The spinning temperature at this time was 300 ° C., a heating cylinder having a length of 300 mm and a temperature of 300 ° C. was used immediately below the spinneret, and the spinning speed was 500 m / min. The spun yarn is continuously drawn 5.9 times without winding it up, heat-treated at a temperature of 220 ° C., and then subjected to a relaxation treatment at a relaxation rate of 3.0% while applying air entanglement to draw 420d, 60 filaments. I got a thread.

In this spinning and drawing, stable spinning was possible without noticeable yarn breakage or generation of fluff.

The filament yarn obtained had a single yarn fineness of 7.
It had a strength of 9.5 g / d and an elongation of 17.2%.

Next, using this filament yarn as a warp yarn and a weft yarn, a plain weave having a weave density of 54 warps / inch and 54 wefts / inch was produced. This weaving was performed without sizing or twisting, but fluff and yarn breakage were hardly generated during the process. The woven density of this fabric after heat setting is 56 warps / inch, weft 5
It was 5 / inch and the cover factor was 2275.

[Comparative Example 5] The number of holes in the spinneret was 240.
In the same manner as in Example 4, except that the spinning speed was 600 m / min and the draw ratio was 5.4, direct spinning and drawing were carried out to obtain a drawn yarn of 420d and 288 filaments.

At this time, a single yarn-to-single yarn collision occurred due to yarn swinging in the heating cylinder, resulting in frequent yarn breakage during drawing.

The filament yarn obtained had a single yarn fineness of 1.
The strength was 46d, the strength was 8.6 g / d, and the elongation was 15.2%.
Next, when weaving was performed in the same manner as in Example 1, weaving could not be performed due to excessive generation of fluff.

[Comparative Example 6] The total polymer discharge amount is increased,
Two-component melt composite spinning and drawing were performed in the same manner as in Example 1 except that the draw ratio was increased to 6.1 times, and the total fineness was 3
35d, 60 filaments, single yarn fineness of composite fiber 5.5
A composite fiber yarn having 8d, strength of 10.2 g / d and elongation of 10.5% was obtained. Some fluff was generated during this yarn production.

Then, as in Example 1, this composite fiber yarn was used for the warp and weft, and the weaving density was 62 warps / inch, 61 wefts.
A book / inch plain weave was produced without sizing or untwisting, but many fluffs were generated during weaving.

Then, this woven fabric was desalinated in the same manner as in Example 1, dried and heat set to obtain a base fabric for an airbag.

The filaments constituting the obtained woven fabric were obtained by finely sizing the composite fibers, and the decomposed yarn of this woven fabric had a total fineness of 310d, a number of filaments of 960, and a single yarn fineness of 0.32d. Strength 9.1 g / d, elongation 12.
It was 1%. The woven density of this woven fabric after heat setting was warp 63 yarns / inch, weft 61 yarns / inch, and the cover factor was 2183, but the quality of the woven fabric surface was poor because of many fluffs. .

The yarn physical properties of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Tables 1 and 2, and the woven fabric properties and the process passability during weaving are shown in Table 3.

[0134]

[Table 1]

[0135]

[Table 2]

[0136]

[Table 3]

As is clear from the results of Table 1, Table 2 and Table 3, in the case of the present invention (Examples 1 to 6), the fiber structure has no mechanical strength, flexibility and process passability. Was excellent. Furthermore, Examples 1 to 2 and 4 in which the weaving density is increased and the cover factor is 1900 or more
In addition to the above-mentioned mechanical strength, flexibility, and process passability, it was found to be an excellent fiber structure that has low air permeability and is well balanced as a base fabric for airbags.

On the other hand, in Comparative Example 1, since the total fineness of the single yarn of the ultrafine fibers after ultrafine was too high, the fiber structure was inferior in flexibility.

In Comparative Example 2, since the strength of the composite fiber yarn and the ultrafine fibers after dividing the composite yarn are low, mechanical properties are improved as compared with the case of Example 2 which is a fiber structure having an equivalent structure. It was inferior and was unsuitable for industrial materials.

In Comparative Example 3, since the weave density was lower than that in Comparative Example 2, the mechanical properties were further inferior.

In Comparative Example 4, the final single yarn fineness is 7.0d.
And it was inferior in flexibility as a fiber structure.

In Comparative Example 5, since fine filament yarns having a single yarn fineness of 1.46d were produced by the direct spinning method, many yarn breakages and fluffs occurred during spinning, and the process passability was poor.

Further, in Comparative Example 6, since the draw ratio during spinning was high and the elongation of the ultrafine fibers was low, many fluffs were generated during weaving and the process passability was also poor.

[Example 5] In order to measure the fiber structure physical properties of the ultrafine fibers in the fiber structures obtained in Example 1, Example 3 and Comparative Example 2, these were obtained in these Examples and Comparative Examples. Cut the sea-island composite fiber yarn to a length of 20 cm and
After arranging 0 to 20 pieces, they are wrapped in gauze and subjected to sea removal treatment in that state to form ultrafine fiber bundles as sample yarns, and the crystal volume value (C), long period in the meridian direction (D
m), crystal orientation (Fc), and amorphous orientation (Fb) were measured. The results are shown in Table 4.

[0145]

[Table 4]

As is clear from Tables 1 to 3, the crystal volume value (C), the long period in the meridian direction (Dm), the crystal orientation degree (F
In the cases of Examples 1 and 3 in which the respective values of c) and the degree of amorphous orientation (Fb) are within the preferred ranges of the present invention, the mechanical strength, light resistance and durability required for industrial material applications are excellent. It was also confirmed from the fiber structure side.

On the other hand, in the case of Comparative Example 2 in which each of the above-mentioned values was out of the preferred range of the present invention, the physical properties suitable for industrial materials could not be obtained.

[0148]

The high-strength ultrafine fiber structure according to the present invention is
Since it is composed of high-strength ultrafine multifilaments having a specific single yarn fineness and a specific high strength, it is possible to provide suitable mechanical properties for industrial material applications,
Moreover, the excellent effect obtained by using the ultrafine fibers can be sufficiently exhibited. In particular, when the fiber structure is a cloth, it has not only mechanical strength but also excellent flexibility and foldability, and further has low gas permeability.

Further, according to the production method of the present invention, generation of fluff and yarn breakage during spinning or production of a fiber structure is sufficiently suppressed, and the above excellent fiber structure is obtained with good spinnability and process passability. Easily obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display part D01F 6/62 303 J

Claims (22)

[Claims] 1. A high-strength multifilament composed of ultrafine fibers having a single yarn fineness of less than 0.8 d, a tensile strength of 6.5 g / d or more, and a breaking elongation of 15% or more. Characteristic high-strength ultrafine fiber structure. 2. The high-strength ultrafine fiber structure according to claim 1, wherein the high-strength multifilament is a polyester fiber. 3. The polyester fiber has an intrinsic viscosity (IV).
Is a polyethylene terephthalate fiber having a value of 0.8 or more. 3. The high-strength ultrafine fiber structure according to claim 2, wherein 4. The high-strength ultrafine fiber structure according to claim 3, wherein the crystal volume value (C) of the polyethylene terephthalate fiber is 8 × 10 ⁴ (angstrom) ³ or more. 5. The high-strength ultrafine fiber structure according to claim 3, wherein the polyethylene terephthalate fiber has a long period (Dm) in the meridian direction of 120 angstroms or more. 6. The high-strength ultrafine fiber structure according to claim 3, wherein the degree of crystal orientation (Fc) of the polyethylene terephthalate fiber is 0.90 or more. 7. The high-strength ultrafine fiber structure according to claim 3, wherein the degree of amorphous orientation (Fb) of the polyethylene terephthalate fiber is 0.975 or more. 8. The high-strength ultrafine fiber structure according to claim 1, wherein the high-strength multifilament is a polyamide fiber having a 98% sulfuric acid relative viscosity (ηrn) of 3.0 or more. 9. The high-strength ultrafine fiber structure according to claim 1, wherein the single-filament fineness of the high-strength multifilament is 0.1 d or more and less than 0.8 d. 10. The high-strength ultrafine fiber structure according to claim 1, wherein all of the ultrafine fibers constituting the high-strength multifilament have substantially the same polymer composition. 11. The high-strength ultrafine fiber structure according to claim 1, wherein the high-strength multifilament is an ultrafine filament yarn produced by sea removal treatment of sea-island type composite fiber. 12. The high-strength ultrafine fiber structure according to claim 1, wherein the fiber structure is a cloth. 13. The high-strength ultrafine fiber structure according to claim 12, wherein the cloth is a woven or knitted fabric composed of multifilaments having a total fineness of 100 to 1000 d. 14. The fabric has a tensile strength of 100 kgf / 3.
cm or more and 60 mm flexibility by the cantilever method
The high-strength ultrafine fiber structure according to claim 13, which is as follows. 15. The high-strength ultrafine fiber structure according to claim 13, wherein the cloth is a base cloth for an airbag, which is made of multifilaments having a total fineness of 180 to 450 d. 16. The high-strength ultrafine fiber structure according to claim 15, wherein the cloth has a cover factor K of 1900 or more and does not have a resin coating layer on its surface. . (Here, the cover factor K of a fabric is a value calculated by the following _{equation.) K = N W × D} W 1/2 + N F × D F 1/2 ( provided that, N _W: warp density (lines / inch ), D _W : Warp yarn fineness (denier), N _F : Weft yarn density (books / inch), D
_F : Weft fineness (denier). ) 17. The high-strength ultrafine fiber structure according to claim 16, which has a gas permeation amount of 5.0 cc / sec / cm ² or less at a pressure drop of a water column of 1.27 cm. 18. A composite fiber yarn having a sea-island type single yarn fineness of 3.0 d or more, which is obtained by simultaneously melt-compounding an island component polymer and a sea component polymer from a single hole of a spinneret to form a filament. After weaving or knitting in the state of a yarn of 120 or less and having substantially no twist and no glue, the sea component polymer is removed, and the single yarn fineness is less than 0.8 d and the tensile strength is 6.5 g /
A method for producing a high-strength ultrafine fiber structure, which comprises producing a high-strength ultrafine fiber structure composed of high-strength multifilaments having a breaking elongation of 15% or more. 19. A high viscosity polymer selected from polyethylene terephthalate having an intrinsic viscosity (IV) of 1.0 or more and polyamide having a 98% sulfuric acid relative viscosity (ηrn) of 3.0 or more as a polymer for an island component to be subjected to melt spinning. The method for producing a high-strength ultrafine fiber structure according to claim 18, which is used. 20. A sea-island type composite fiber is produced by a spinning method in which a high-temperature atmosphere of 200 to 350 ° C. is provided immediately below the spinneret, slowly spinning, cooling, refueling, and then stretching 3.0 times or more. The method for producing a high-strength ultrafine fiber structure according to claim 18, which is characterized. 21. The method for producing a high-strength ultrafine fiber structure according to claim 18, wherein the island component polymer is one type. 22. A high-strength composite fiber having a sea-island type cross section and a tensile strength of 7.0 g / d or more.