JPH07189074A - Heat-resistant and flameproof fabric - Google Patents

Abstract

PURPOSE:To provide fabric, having excellent heat resistance and flameproof characteristics and suitable as a heat- and flame-resistant fabric, especially heat- and flame-resistant clothes excellent in required characteristics thereof such as dyeability as clothes. CONSTITUTION:This heat- and flame-resistant fabric is composed of composite yarns of polybenzazole fibers and cellulosic fibers to which flame resistance is imparted and further the heat- and flame-resistant fabric is composed of the composite yarns in which the polybenzazole fibers are arranged in the core parts of the yarns and the cellulosic fibers to which the flame resistance is imparted are arranged in the peripheral parts of the yarns. Required characteristics as clothes such as dyeability and a visual feeling which have been problems in applying the polybenzazole fibers to the heat- and flame- resistant fabric are solved to afford the fabric having high heat and flame resistances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fabric having heat resistance and flame resistance, and more particularly to heat resistance, flame resistance clothing, fire blocking layer, heat resistance, flame resistance sheet and the like represented by fire fighting clothing, heat resistant work clothing and the like. It relates to a suitable fabric.

[0002]

2. Description of the Related Art Conventionally, heat resistance, heat resistance using flame-retardant materials, and flame resistant clothing have been developed.
The fabrics that make up flame-resistant clothing include flame-retardant-containing cotton (called FR cotton, etc.), aromatic meta-aramids (brand name: Conex, Nomex, etc.), aromatic para-aramids (brand name: Kevlar, etc.), poly Those comprising benzimidazole or a blend thereof are known and put to practical use. Among them, aromatic meta-aramid fibers exhibiting excellent heat resistance and flame resistance have been widely used as heat and flame resistant clothing because they can be colored. However, aromatic meta-aramid fibers have a problem of puncture damage due to heat shrinkage when exposed to flames, and a method of mixing aromatic para-aramid fibers has been proposed as a means for solving the problem (for example, Japanese Patent Laid-Open Publication No. Hei 10 (1999) -135242). 1-
221537). Although fabrics suitable for heat-resistant and flame-resistant clothing have been provided by these methods, their performance was not sufficient, for example, 400 to 500 ° C. when evaluated at the thermal decomposition temperature. Therefore, heat resistant and flame resistant fabrics having higher performance have been desired. On the other hand, in recent years, a polybenzazole fiber having very high heat resistance has been developed, and it is expected that a very excellent heat resistant and flame resistant fabric can be obtained by using the fiber. However, the polybenzazole fiber is inferior in dyeing property, which is important for aesthetics as a clothing, and has a problem in aesthetics as a fabric used for heat resistant and flame resistant fabrics, especially heat resistant and flame resistant clothing.

[0003]

SUMMARY OF THE INVENTION That is, the present invention provides a heat-resistant and flame-resistant fabric having excellent heat-resistant and flame-resistant properties which have not been found in the past and having excellent dyeing properties and other necessary properties for clothes.
In particular, the present invention provides a cloth suitable for heat-resistant and flame-resistant clothes.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to provide a fabric having excellent heat resistance and flame resistance properties that have not been obtained in the past, and as a result, the present invention has been achieved. That is, the present invention is a heat resistant and flame resistant fabric composed of a composite yarn of polybenzazole fiber and a cellulosic fiber to which flame resistance has been imparted, and further, the polybenzazole fiber has imparted flame resistance to the core of the yarn. By providing a composite yarn in which cellulosic fibers are arranged in the peripheral portion of the yarn, it is possible to provide a heat-resistant and flame-resistant fabric that also has aesthetic properties by utilizing the good dyeing properties of the cellulosic fibers.

The polybenzazole fiber in the present invention means a fiber made of polybenzazole polymer, and polybenzazole (PBZ) means polybenzoxazole (PBO) homopolymer and polybenzothiazole (PBZ).
BT) homopolymers and random, sequential or block copolymers of PBO and PBT thereof. Here, polybenzoxazole, polybenzothiazole and their random, sequential or block copolymers are described, for example, in Wolfe et al.
Crystalline Polymer Compositions, Process and Pro
ducts '' US Patent 4,703,103 (October 27, 1987),
`` Liquid Crystalline Polymer Compositions, Process
and Products "US Patent 4,533,692 (August 6, 19
85), `` Liquid Crystalline Poly (2,6-Benzothiazole)
Compositions, Process and Products '' US Patent
4,533,724 (August 6, 1985), "Liquid Crystalline
Polymer Compositions, Process and Products '' USP
atent 4,533,693 (August 6,1985), Evers "Thermo
oxidatively Stable Articulated p-Benzobisoxazolean
d p-Benzobisthiazole Polymers '' US Patent 4,359,56
7 (November 16,1982), “Method for making” by Tsai et al.
Heterocyclic Block Copolymer '' US Patent 4,578,432
(March 25, 1986).

The structural unit contained in the PBZ polymer is preferably selected from lyotropic liquid crystal polymers. The monomer units are described in Structural Formulas (a)-(h). The polymer preferably consists essentially of monomeric units selected from structural formulas (a)-(h),
More preferably, it consists essentially of monomer units selected from structural formulas (a)-(c).

[0007]

[Chemical 1]

[0008]

[Chemical 2]

Suitable solvents for forming the dope of PBZ polymer include cresol and non-oxidizing acids capable of dissolving the polymer. Examples of suitable acid solvents include polyphosphoric acid, methanesulfonic acid and concentrated sulfuric acid or mixtures thereof. Further suitable solvents are polyphosphoric acid and methanesulfonic acid. The most suitable solvent is polyphosphoric acid.

The polymer concentration of the solution is preferably at least about 7% by weight, more preferably at least 1%.
It is 0% by weight, most preferably at least 14% by weight. The maximum concentration is limited by practical handling characteristics such as polymer solubility and dope viscosity. Due to these limiting factors, the polymer concentration is usually 20% by weight.
Never exceeds.

Suitable polymers, copolymers or dopes are synthesized by known methods. For example, Wolfe et al.
USPatent 4,533,693 (August 6,1985), Sybert et al.
S.Patent 4,772,678 (September 20,1988), Harris U.
S.Patent 4,847,350 (July 11,1989). PBZ
The polymer is US Patent 5,089,591 (Febru
According to ary 18, 1992), it is possible to achieve a high molecular weight at a high reaction rate in a dehydrating acid solvent under relatively high temperature and high shear conditions.

The dope in which the polybenzazole polymer is dissolved in a solvent is spun by a known dry-wet spinning method.
That is, the dope is discharged from the spinneret, and the fibrous dope is passed through the gas and then contacted with the liquid to be spun. The method of separating the PBZ polymer from the fibrous dope is known as coagulation. Tan and spinning technology
U.S. Patent 4,263,245 (April 21, 1981), Wolfe et al.
S.Patent 4,533,693 (August 6, 1985), Adams et al., `` Th
e Marerials Science and Engineering of Rigid Rod P
olymers '' pp247-49, pp259-60 (Marerials Reaearch So
ciety 1989).

The fibrous dope that has passed through the gas is brought into contact with the fluid. The liquid may be in vapor form, but is preferably liquid. The liquid is contacted with the fibers in a liquid bath or by spraying. The liquid is water or a mixture of water and an acid, preferably a phosphoric acid solution having a concentration of 30% by weight or less.

After coagulation, the residual solvent in the fibers is further washed with fluid. The coagulation fluid and the cleaning fluid may be the same or different. The washing is continuously performed until the residual solvent in the fiber reaches a predetermined concentration. When the solvent is polyphosphoric acid, the residual solvent concentration in the fiber is preferably about 5000 ppm or less, more preferably about 3 ppm.
It is 000 ppm or less. The fibers after washing with water usually have 30% by weight or more of washing liquid or residual coagulation liquid. If necessary, the thread after washing with water may be neutralized.

The cleaning liquid or the residual coagulating liquid is dried in a heating zone installed continuously or discontinuously. The heating zone is, for example, an electric furnace, a heating roller or a heating inert gas, or a combination thereof, and if the residual washing liquid (or coagulating liquid) of the obtained dry yarn can be brought to a desired concentration, its means It doesn't matter. When an electric furnace, a heating roller or the like is used as the heating zone, the atmosphere may be air, but an inert gas atmosphere such as nitrogen, helium or argon is preferable.

The polybenzazole fiber in the present invention is
The equilibrium moisture content is preferably 5% or more. Substantially equilibrium water content means the weight fraction of water when left to stand until the change in water content is substantially no longer observed in an atmosphere of a temperature of 20 ° C. and a humidity of 65%, generally under the conditions described above. After leaving for 30 to 40 days, the measurement is performed. When the equilibrium moisture content is 5% or more, the heat resistance and flame resistance characteristics are further improved, but this mechanism is not clear. One possibility is that the heat of vaporization of water may enhance its flame resistance effect.

As a result of extensive studies to obtain fibers having a substantial equilibrium water content of 5% or more, it was found that the above-mentioned drying step can be achieved by carrying out the following recommended conditions. That is, the drying conditions are adjusted so that the water content after the drying step is 5% or more. Preferably 140 ° C
The drying time is adjusted so that the water content after the drying step is 5% or more at the above drying temperature, and more preferably 18
The moisture content after the drying process is 5% at the drying temperature of 0 ° C or higher.
The drying time is adjusted as described above. The drying temperature here is the highest drying temperature, and for example, in the case of performing drying in multiple stages, it means the temperature in the process that has the highest temperature among them. The drying time can be adjusted by changing the zone length effective for drying. The mechanism by which the equilibrium moisture content of the fiber obtained under these recommended conditions is 5% or more is not clear, but it is dried rapidly at high temperature so that the moisture content after drying becomes 5% or more. It is speculated that this is due to the formation of a structure that easily retains a certain amount of water.

The cellulosic fibers to which flame resistance is imparted are so-called flame-retardant cellulosic fibers having flame resistance, and if specifically preferred examples thereof are 1 to 5% by weight with respect to the fiber weight. Of cotton, rayon, polynosic fiber or a mixture thereof with phosphorus atoms added thereto, more preferably 0.5 to 3% by weight of nitrogen atoms based on the weight of the fibers is added. The above fibers are referred to. The above-mentioned cellulose fibers have a limiting oxygen index value (LOI value) evaluated by JIS K7201 of 23 or more, preferably 25 or more, more preferably 27 or more. When the phosphorus content is 1% by weight or less, the flame resistance imparted is insufficient. On the other hand, the phosphorus content is 5
If it exceeds 0.1%, the production process is adversely affected and the strength of the fiber is adversely affected.

The flame-resistant cotton is preferably cotton post-treated with a phosphorus-containing and / or nitrogen-containing compound. The rayon or polynosic fiber having flame resistance may be post-processed. For example, Japanese Patent Publication No. 48-2
A fiber obtained by adding a polyphosphonate compound having a molecular weight of about 500 to 10,000 to a spinning stock solution for producing viscose artificial fiber as described in Japanese Patent No. 693 and spinning by a conventional method is preferable. Of course, it may be a compound containing phosphorus and nitrogen in the same molecule. The above post-processing may be performed before or after being combined with the polybenzazole fiber.

The composite yarn of the polybenzazole fiber and the cellulosic fiber provided with flame resistance may have both fibers uniformly mixed, but from the viewpoint of aesthetics after dyeing, the polybenzazole fiber is It is preferable that cellulosic fibers having flame resistance and good dyeability are arranged in the core of the yarn in the peripheral portion of the yarn.

The composite yarn in which the polybenzazole fiber and the cellulosic fiber provided with flame resistance are uniformly mixed can be obtained by a known blending method. For example, it can be obtained by cutting the polybenzazole fiber, then mixing it with the cellulose-based short fiber, and performing the usual spinning process. A composite yarn in which polybenzazole fibers are arranged in the core of the yarn and cellulosic fibers to which flame resistance is imparted are arranged in the peripheral portion of the yarn are described in JP-A-57-5924. A method of combining at the spinning machine stage, for example, JP-A-3-2
No. 69129, a method of arranging a cellulosic fiber spun yarn around a filament of a polybenzazole fiber, a method of using a spun yarn instead of a filament as the core polybenzazole fiber, and the like. However, its structure is important in the present patent, and its manufacturing method does not matter. The mixing ratio of the polybenzazole fiber in the composite yarn is preferably 10% or more and 90% or less, more preferably 20% or more and 80% or less. The composite yarn obtained by the above method is preferably cotton count 7-8.
It is 0, more preferably 10 to 60.

The cloth used in the present invention is the above-mentioned composite yarn.
It refers to a structure formed from the above, and its organizational structure does not matter.
For example, plain weave, satin weave, and twill weave
Knitted fabrics of various structures can be mentioned. The basis weight is preferably
50 g / m² ~ 500g / m ² , And more preferably 10
0 g / m² ~ 350g / m² Is.

The cloth composed of the composite yarn of the polybenzazole fiber thus obtained and the cellulosic fiber having flame resistance is an obstacle when using only the polybenzazole fiber as a heat resistant and flame resistant cloth. The dyeability is improved, and further, the texture is improved by the combination, and the flame propagation preventing function of the polybenzazole fiber improves the flame resistance of the fabric. Furthermore, it also suppresses the shrinkage of the cloth, which is important for heat resistant and flame resistant cloths. In particular, this effect is remarkable in the fabric made of the composite yarn in which the polybenzazole fiber is arranged at the core of the yarn and the cellulosic fiber having flame resistance is arranged at the peripheral portion of the yarn.

[0024]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not restricted to the examples as long as the gist of the invention is not exceeded.

Example 1 A spinning dope prepared by dissolving cis-polybenzoxazole having an intrinsic viscosity of 30 dl / g in polyphosphoric acid at a concentration of 14% was obtained at 160 ° C. from a 334-hole nozzle having an orifice diameter of 0.22 mm. It was pushed out with a single hole discharge rate of 0.122 cc. The fibrous dope extruded from the nozzle passes through a 22 cm air gap,
In it, it was pulled, passed through a coagulation bath adjusted to about 22 ° C, and continuously washed with 5 pairs of rollers at a running speed of about 200 m / min, and then continuously without being wound once. Then, it was dried in the following drying process.
Four drying rollers were used for drying, and each temperature was set to 180 ° C, 220 ° C, 220 ° C, and 220 ° C in order.
By adjusting the residence time of each roller to about 17 seconds, a final polybenzoxazole fiber having a water content of 1.1% was obtained. The obtained fiber has a tensile strength of 42 g / d, a breaking elongation of 2.8% and a tensile elastic modulus of 165.
It was 0 g / d and the water content was 0.5%. The equilibrium moisture content was measured and found to be 1.7%.

The obtained polybenzoxazole fiber was cut to an average fiber length of 51 mm, and the raw cotton and cotton were uniformly mixed and spun to obtain a 14th yarn having a ratio of 55% polybenzoxazole fiber and 45% cotton. A spun yarn was produced, and a twill fabric having a basis weight of 320 g / m ^{2 was} further obtained. A flameproofing agent (Pyrovatex C) containing this woven fabric as an active ingredient of N-methyloldimethylphosphonopropionamide.
(P, manufactured by Ciba Geigy) 30% by weight and 0.5% by weight of ammonium chloride, dipped in an aqueous solution, squeezed with a mangle to obtain a wet pickup of 60% by weight, dried and heat-treated to obtain heat-resistant and flame-resistant cloth. It was

"Example 2" A polybenzoxazole fiber obtained by the same method as in Example 1 was used, and the average fiber length was 51 mm.
The raw cotton and the cotton are cut into a number 14 composite yarn in which the polybenzoxazole fiber is arranged at the core of the yarn and the cotton fiber is arranged around the polybenzoxazole fiber by the method described in JP-A-57-5924. Obtained. The composite ratio of polybenzazole fibers in this yarn was 35% by weight. Using this composite yarn, a twill weave having a basis weight of 310 g / m ² was obtained. Further, this woven fabric was post-treated in the same manner as in Example 1 to obtain a heat resistant and flame resistant fabric.

[Example 3] Polybenzoxazole fiber obtained by the same method as in Example 1 was used, and the average fiber length was 51 mm.
Cut into pieces to obtain raw cotton. A raw cotton comprising flame-resistant treated polynosic fibers obtained by adding polyorganophosphazene to the viscose spinning bath so as to contain 2.8% by weight of phosphorus according to the method of Example 1 of JP-B-48-2633. It was The respective raw cottons were mixed and spun to obtain a 20th composite yarn having a polybenzoxazole fiber composite ratio of 60% by weight, which was further used to obtain a twill fabric having a basis weight of 310 g / m ² .

Example 4 Polybenzoxazole fiber obtained by the same method as in Example 1 was used, and the average fiber length was 51 mm.
Cut into A 40 count yarn was spun from this raw cotton, and a 20th composite spun yarn was produced by winding the 40th flame-resistant treated polynosic spun yarn similar to that described in Example 3 around the periphery of this yarn as a core yarn. . The weight fraction of the polybenzoxazole fiber was 50%. A twill fabric having a basis weight of 290 g / m ² was obtained using this composite yarn.

[Example 5] Polybenzoxazole fibers were obtained in the same manner as in Example 1 except that the drying temperature was 1
By setting the temperature to 60 ° C, 180 ° C, 180 ° C, 180 ° C, a fiber having a moisture content of 7.5% was obtained. The strength of this fiber was 41 g / d, the elastic modulus was 1590 g / d, and the equilibrium moisture content was 6.2%. A similar twill fabric was obtained after forming a composite yarn with cotton in the same manner as in Example 1.

"Example 6" The polybenzoxazole fiber in Example 4 was equilibrium moisture content of 6.2% in Example 5.
In the same manner as above, except that the fiber of No. 1 was used, a composite yarn with a flame-resistant polynosic fiber and a twill fabric made of the same were obtained.

Comparative Example 1 Polybenzazole fiber obtained in the same manner as in Example 1 was cut into an average fiber length of 51 mm, and a spun yarn of 14th count was obtained from this raw cotton by a conventional method. Using this yarn, a twill fabric having a basis weight of 270 g / m ² was obtained.

Comparative Example 2 A spun yarn of No. 14 was obtained from the raw cotton of the flame-resistant treated polynosic fiber obtained in Example 3 by a conventional method. A twill fabric having a basis weight of 280 g / m ² was obtained using this yarn.

Comparative Example 3 Kevlar 29 produced by DuPont having a mean fiber length of 40 mm was used in place of the polybenzazole fiber, and the basis weight was 280 g in the same manner as in Example 2.
A twill fabric of / m ² was obtained and the post-treatment was carried out in the same manner.

Using the woven fabrics of Examples 1 to 6 and Comparative Examples 1 to 3, heat resistance and flame resistance properties were evaluated according to JIS L1091 A-4 method. However, the sample pretreatment is performed at a temperature of 20.
It was only stored for 24 hours at a temperature of 65 ° C. and a humidity of 65%. Further, the dyeability was dyed with Direct Sky Blue 6B (manufactured by Sumitomo Chemical Co., Ltd., CI = Direct Blue 1) according to a conventional method, and judged visually. The results are summarized in Table 1.

[0036]

[Table 1]

[0037]

EFFECTS OF THE INVENTION According to the present invention, the necessary properties for clothing such as dyeability and texture, which have been problems when the polybenzazole fiber is applied as a heat-resistant and flame-resistant cloth, are solved, and high heat resistance and flame resistance which have not been found in the past have been solved. A fabric having a property was obtained.

Claims (2)

[Claims] 1. A heat resistant and flame resistant fabric comprising a composite yarn of polybenzazole fiber and a cellulosic fiber provided with flame resistance. 2. A heat-resistant and flame-resistant fabric comprising a composite yarn in which polybenzazole fibers are arranged at the core of the yarn and cellulosic fibers imparted with flame resistance are arranged at the periphery of the yarn.