JP2001172845A - Heat-resistant and flame-retardant woven or knit fabric having excellent resistance to light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide woven or knit fabrics that has excellent resistance to light and high resistance to heat and is suitably useful as an industrial material, particularly suitable as a clothing material for heat-resistant suits and fireman uniforms. SOLUTION: This light-resistant, heat-resistant and flame-retardant woven or knit fabric comprises a fabric at least partially including polybenzazole fibers to which a light-fastness agent, for example, an oxidation dye compound that can reduce the regular reflection factor of the fiber to <=30% in >=30% area in the wavelength range from 450 to 700 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant and flame-retardant woven fabric containing polybenzazole fiber which is particularly excellent in light resistance and is suitable as a material for heat-resistant clothing or fire-fighting clothing.

[0002]

2. Description of the Related Art In recent years, polybenzazole fibers have twice the strength and elastic modulus of para-aramid fibers, which are representative of super fibers currently on the market, and have a limiting oxygen index of 68 and a decomposition temperature of 650 ° C. Because of its high heat resistance, it is expected as a next-generation super fiber.

[0003] It is known to produce a molded article from a polybenzazole polymer polyphosphoric acid solution. For example, the production conditions are described in US Pat. No. 5,296,185 and US Pat.
There is 385702, and the washing and drying method is W094 / 04726
No. 5,296,185 are disclosed in US Pat. No. 5,296,185.

[0004]

However, as described above, a polybenzazole molded article having extremely suitable physical properties as an industrial material has a problem that when it is physically damaged, its light resistance is reduced, and in particular, light in the visible light region is reduced. However, there is a drawback that the strength is reduced when exposed to water. Physical damage includes what is referred to as a kink band, for example, when it is bent or subjected to shear forces. The kink band is observed, for example, as a black stripe under a microscope of 200 times. Polybenzazole fiber is expected to be used as a material for heat-resistant or fire-fighting clothing due to its high heat resistance and flame retardancy, but its light resistance is reduced due to physical damage in the weaving and knitting processes. The storage conditions and use conditions of heat-resistant clothes and fire-fighting clothes to be used are limited, and woven and knitted fabrics having excellent light resistance have been desired. The present inventors have conducted intensive studies to obtain a woven or knitted fabric that is lightweight, yet has high strength and high elastic modulus, high heat resistance, and high light resistance, and is particularly suitable for heat-resistant clothing or firefighting clothing. Completed.

[0005]

That is, the present invention relates to a polybenzazole which is provided with a light-resistant agent having a regular reflectance of 30% or less in a region of 30% or more in a wavelength range of 450 nm to 700 nm. A heat-resistant and flame-retardant woven knitted fabric excellent in light resistance, characterized by containing fibers at least in part. More specifically, the light resistance is excellent in the light resistance as described above, wherein the regular reflectance of the fiber is 20% or less in a region of 10% or more in a wavelength range of 450 nm to 700 nm. The heat-resistant and flame-retardant woven knitted fabric, wherein the light-resistant agent is an oxidation dye compound, the heat-resistant and flame-retardant woven knitted fabric having excellent light-resistance described above, wherein the light-resistant agent comprises a compound comprising an aromatic amine or phenols. The compound described above is characterized by excellent heat resistance and light resistance described above.
The flame-retardant woven or knitted fabric and the light-proofing agent are 0.01 to 20.
The heat-resistant and flame-retardant woven knitted fabric having excellent light resistance described above, which is provided by 0% by weight.

Hereinafter, the present invention will be described in more detail. The polybenzazole molded article in the present invention is a polyparaphenylene benzobisoxazole (PBO) homopolymer and a random, sequential or block copolymer of polybenzazole (PBZ) containing at least 85% of a PBO component. A polymer refers to a polymer. Here, polybenzazole (PBZ) polymer is described in, for example, "Liquid Cry" by Wolf et al.
stalline Polymer Compositions, Process and Product
s "U.S. Patent No. 4,703,103 (October 27, 1987),
`` Liquid Crystalline Polymer Compositions, Process
and Products, U.S. Patent No. 4,453,692 (August 6, 1985), "Liquid Crystalline Poly (2,6-Benzothiazol)
e) Compositions, Process and Products '' U.S. Patent No. 4
533724 (August 6, 1985), "Liquid Crystalli
ne Polymer Compositions, Process and Products, U.S. Pat.No. 4,453,693 (August 6, 1985); Evers, "Thermooxidative-ly Stable Articulated p-Benzobis.
oxazole and p-Benzobisoxazole Polymers '' U.S. Patent No.
4539567 (November 16, 1982), Tsai et al.
hod for making Heterocyclic Block Copolymer "U.S. Pat. No. 4,578,432 (March 25, 1986).

The structural units contained in the PBZ polymer are preferably selected from lyotropic liquid crystal polymers. The monomer units consist of the monomer units described in Structural Formulas (a)-(h), and more preferably consist essentially of the monomer units selected from Structural Formulas (a)-(c).

[0008]

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[0009]

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

The concentration of the polymer in the solvent is preferably at least about 7% by weight, more preferably at least about 10% by weight.
%, Most preferably 14% by weight. The maximum concentration is limited by practical handling properties such as, for example, polymer solubility and dope viscosity. Due to these limiting factors, the polymer concentration does not exceed 20% by weight.

[0012] Suitable polymers, copolymers or dopes are synthesized by known techniques. See, for example, Wolfe et al., US Pat. No. 4,453,693 (August 6, 1985); Sybert et al., US Pat. No. 4,772,678 (September 20, 1988);
Synthesized by the method described in US Pat. No. 4,847,350 to ris (July 11, 1989). Polymers consisting essentially of PBO are disclosed by Gregory et al. In US Pat.
According to this method, it is possible to increase the molecular weight at a high reaction rate under relatively high temperature and high shear conditions in a dehydrating acid solvent.

The dope polymerized in this way is supplied to the extruding section, and is discharged from the extrusion die at a temperature of usually 100 ° C. or higher. The polymer dope requires a sufficient draw zone length as described in U.S. Pat. No. 5,296,185 to obtain a sufficient draw ratio (SDR), and has a relatively high temperature (spinning at or above the solidification temperature of the dope). It is preferable that the cooling air is uniformly cooled by the rectified cooling air having a temperature equal to or lower than the temperature. The length (L) of the draw zone needs to be a length that completes solidification in a non-coagulating gas, and is roughly determined by the single hole discharge amount (Q). In order to obtain good fiber properties, the draw-out stress of the draw zone needs to be 2 g / d or more in terms of polymer (assuming that only the polymer is stressed).

The polymer drawn in the draw zone is then led to an extraction (coagulation) bath. Since the tension is high, no consideration is required for the disorder of the extraction bath, and any type of extraction bath may be used. For example, funnel type, water tank type, aspirator type or waterfall type can be used. The extract is desirably a phosphoric acid aqueous solution or water. Finally, the phosphoric acid contained in the polymer in the extraction bath is 99.0% or more, preferably 99.5%.
Extract above. The liquid used as the extraction medium in the present invention is not particularly limited, but is preferably water, methanol, ethanol, acetone or the like which is substantially incompatible with polybenzazole. Alternatively, the extraction (coagulation) bath may be separated into multiple stages, the concentration of the phosphoric acid aqueous solution may be reduced gradually, and finally, the surface may be washed with water. Further, the fiber bundle is desirably neutralized with an aqueous sodium hydroxide solution or the like and washed with water.

As a method of applying the light-fast agent, there is a method of first applying the agent in a molded product manufacturing process line. In this case, at any position after the completion of polymerization and immediately before extrusion, or at any position before and after entering the coagulation bath and before entering the drying bath after extruding the dope from the extrusion die in the manufacturing process. Good. A general method may be used as the method of applying, but is not limited to the following. For example, in order to apply to an extruded dope, kneading the polybenzazole and the light stabilizer after polymerization is completed in a biaxial kneader until the light stabilizer is uniform, and then extruding spinning, dissolving the light stabilizer in the coagulant in advance Every time, during or before and after passing through the dope of the normal composition and solidifying it, passing through the washing step and the neutralization step,
There are a dipping method, a kiss-roll method, a guide method, and a method of spraying the solution on a roller to apply the solution, which is dissolved in an aqueous solution containing a light stabilizer or an organic solvent. Further, a method of imparting a light-proofing agent at the time of post-processing such as dyeing after manufacturing the molded article can also be adopted.

A large number of fine holes called capillaries are present inside the polybenzazole molded body, and the moisture of the molded body before drying is present in the capillaries. Moreover, the holes are connected to each other and communicate from outside to inside. Therefore, it is desirable to apply the light-resistant agent at a stage after solvent extraction (coagulation) and before drying in order to enable mass transfer using the connected capillary and to guide the external light-resistant agent to the inside. In fact, when the light-proofing agent is applied from the coagulation bath before entering the drying step, the immersion time is 0.1 seconds or more, preferably 0.5 seconds or more, and most preferably 1 second or more and any amount of light-fasting agent is sufficient. However, if the immersion time is too long, the production cost increases, which is not preferable.

Examples of the light fastening agent to be applied include, but are not limited to, an oxidation dye compound which oxidizes with an oxidizing agent containing air to form a color, a compound comprising an aromatic amine or a compound comprising a phenol. Oxidation dyes do not use dyes that are synthesized by oxidation in the case of dyes, but use intermediates that generate dyes by oxidation.Strictly speaking, they are bases that generate oxidation dyes, and are also called oxidation bases. Things. As a compound composed of an aromatic amine or a compound composed of phenols,
Aniline, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-aminophenol, m-
Examples include aminophenol, p-aminophenol, naphthol, and derivatives thereof, and acid salt compounds thereof. Generally, since such compounds are solid or liquid, except when directly added to the dope,
Use it after dissolving it in a solvent. As the solvent to be dissolved, water, an aqueous solution such as a phosphoric acid aqueous solution, ethanol, methanol, alcohols such as ethylene glycol, ketones such as acetone, and the like, as long as they have compatibility with the light-fast agent and penetrate into the fiber. good. The solution can be used by accelerating the oxidation / condensation of the light-fast agent with sodium hypochlorite, hydrogen peroxide, iron chloride (iii), sodium nitrite, air or the like. The light stabilizer is colored, reacts or adsorbs with the polybenzazole molded product, and hardly drops off in the next washing step. When water is used as a solvent in consideration of environment, safety and waste liquid treatment, a phenylenediamine compound which has high solubility and easily oxidizes and develops color only with air is most preferable. It is also possible to simultaneously add two or more kinds of oxidation dye compounds. When different kinds of oxidation dye compounds are used together,
The speed of oxidation and color development may be significantly increased, and different effects can be obtained.

Considering the diffusion and infiltration into the polybenzazole molded article, it is desirable that the concentration of the light-resistant agent solution be as high as possible. However, if the concentration is unnecessarily high, the strength is reduced by the weight fraction applied. The waste liquid load from the washing process increases. In addition, it is desirable that the immersion in the light-resistant agent solution be as long as possible, but equipment cost is a problem. Depending on the sample form of polybenzazole, it is necessary to optimize the concentration of the light-fast agent solution and the immersion time in the light-fast agent solution.
It can be treated by immersing it in a solution of 20% by weight to 20% by weight within 10 minutes, preferably within 5 minutes, more preferably within 1 minute, and further within 30 seconds.

After washing with water, drying (heat treatment) at 100 ° C. or higher, usually within 300 ° C., loses the connection between the capillaries, and the light-proofing agent can be easily fixed inside the fiber. The strength after the heat treatment is 35 g / d or more, and it is important to reduce the adverse effect on the polymer by the heat treatment.

As a condition for the molded article of the present invention to exhibit effective light resistance, first, the molded article has a wavelength of 450 nm to 700 nm.
30% or more, preferably 80% or more between nm
More preferably, it is important that a light-resistant agent is added in a region of 95% or more so that the regular reflectance of the molded body is 30% or less. In addition, a light-resistant agent that makes the regular reflectance of the molded body 20% or less is provided in a region of 10% or more, preferably 30% or more in a wavelength range of 450 nm to 700 nm. As an agent, for example, it is desirable to color black, purple, or brown, which is characteristic of an oxidation dye. FIG. 1 shows a regular reflectance spectrum of an untreated polybenzazole fiber and a regular reflectance spectrum of a polybenzazole fiber treated with an oxidation dye substance p-phenylenediamine.

Secondly, it is important to use a light-proofing agent capable of minimizing a decrease in strength due to heat treatment. After the light-resistant agent is applied to the polybenzazole fiber, a drying treatment is performed at a high temperature of, for example, about 100 ° C. to 350 ° C., and when the light-resistant agent is applied, a significant decrease in strength is observed.
The excellent physical properties inherent in polybenzazole fiber cannot be maintained. Therefore, it is important to select a light stabilizer from such a viewpoint, and specifically, the above-mentioned light stabilizer is recommended. Third, it is desirable that an appropriate amount of a light-resistant agent is contained inside the molded body. Preferably 0.01% or more and 20.0% or less, most preferably 0.5% or more and 10.0% or less by weight%.
It is important that they contain the following amounts: The content of the light-resistant agent can be confirmed by a difference in weight per fixed length, area or volume between the untreated molded article and the light-resistant agent-treated molded article.

The chemical existence state and action of the lightfast compound inside the fiber are not clearly understood.
It is presumed that the acid dye having a light-shielding property due to coloring and a long conjugated system and having a small oxidation-reduction potential is electron-donating or radical-scavenging, or is stabilized by reaction with a polymer and coordination. You are not bound by.

From the obtained light-resistant polybenzazole fiber, short crimped polybenzasol fiber can be obtained by crimping and cutting by known methods. As the processing method, the method described in JP-A-7-292533 or JP-A-8-144132 is recommended because the strength of the polybenzazole fiber is extremely high, but is not limited thereto. Absent. Using the obtained polybenzazole short fibers, a spun yarn can be obtained by a known spinning method. At that time, short fibers other than polybenzazole can be mixed according to the purpose.
As short fibers to be mixed, para-aramid fiber, meta-aramid fiber, polyimide fiber, polyamide-imide fiber,
Polybenzimidazole fiber, melamine fiber and the like can be mentioned, but a fiber having a limiting oxygen index (LOI) of 25 or more is preferable. Since polybenzazole short fibers have extremely high heat resistance and flame retardancy, if the mixing ratio of polybenzazole short fibers is 5% or more, excellent heat resistance and flame retardancy can be exhibited. It is possible. From the obtained polybenzazole spun yarn, heat resistance and excellent heat resistance by known plain weaving, twill weaving, satin weaving, circular knitting, warp knitting, etc.
A woven or knitted fabric for a firefighting suit can be obtained. In weaving and knitting, it is also possible to mix spun yarn containing polybenzazole fibers with other heat-resistant and flame-retardant fibers, that is, to carry out weaving or knitting.

Hereinafter, the measuring method used in the present invention will be described. <Measurement method of visible reflection spectrum> As an ultraviolet / visible spectrophotometer, a Hitachi U-3500 type self-recording spectrophotometer was used. An angled (10 °) spacer is attached to the setting place of the reflection sample of the 60φ integrating sphere device equipped with the ultra-high sensitivity Photomar R928 detector, and the specular side of the molded sample having a thickness of 3 mm or more is attached without any gap, and the regular reflection spectrum is obtained. It was measured. A sub-white plate of aluminum oxide was attached to the surface on which the sample was placed, and the obtained reflection spectrum was defined as a regular reflectance of 100% to obtain a regular reflectance spectrum of the sample. 5 mm long thin fiber sample
And cut at a pressure of 8 t / cm ² or more for 2 minutes or more,
It was press-molded to a uniform thickness of at least mm and used as a sample.
Detailed measurement conditions are as follows. Measurement wavelength: 300 nm to 700 nm Scan speed: 600 nm / min Slit (visible): 5.00 nm Photomal voltage: automatic control PbS sensitivity: 2

<Evaluation Method of Light Resistance> The light resistance was evaluated by measuring the strength of the fabric before and after light exposure.
The light exposure test used a water-cooled xenon arc type weather meter (model Ci35A) manufactured by Atlas. Wrap the molded body around the metal frame and set it in the device, quartz on the inner filter glass, porosicate on the outer filter glass,
Using type S, irradiance 0.35 W / m ² (at
(340 nm), a black panel temperature of 83 ± 3 ° C., and a humidity of 50 ± 5% in a test vessel, and continuous operation was performed for 100 hours.

<Measurement method of strength>
This was performed by the labeled strip method of ISL1096.

[0027]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 Polyparaphenylene benzobisoxazole 14.0 having an intrinsic viscosity of 24.4 dL / g measured in a methanesulfonic acid solution at 30 ° C., obtained by the method described in US Pat. No. 4,453,693. A spinning dope consisting of polyphosphoric acid with a weight percent and a phosphorus pentoxide content of 83.17% was used for spinning. The dope is passed through a metal mesh filter medium, and then kneaded and defoamed with a kneading device consisting of two axes, and then the pressure is increased, and the temperature of the polymer solution is maintained at 170 ° C.
After spinning at 170 ° C. from a spinneret having 160 holes and cooling the discharged yarn using cooling air at a temperature of 60 ° C., it is wound around a godet roll to give a spinning speed, and the temperature is adjusted to 20 ±
Extraction (coagulation) consisting of 20% phosphoric acid aqueous solution maintained at 2 ° C
Introduced into the bath. Subsequently, the yarn is washed with ion-exchanged water in a second extraction bath, and then immersed in a 0.1 mol / L sodium hydroxide solution to perform a neutralization treatment.
It was immersed in a black aqueous solution of p-phenylenediamine by weight for 60 seconds. After washing with water for 10 seconds, it was dried at 120 ° C. for 120 seconds. From the obtained fiber, JP-A-7-29253
Polyparaphenylene benzobisoxazole (PBO) short fibers having a cut length of 44 mm were produced by the method described in No. 3. The obtained PBO short fiber and Teijin's Technora short fiber (cut length 51 mm) were mixed with 60/40 (PBO).
The blended cotton was mixed at a ratio of short fibers / technola staple fibers) and subjected to ordinary carding, drawing, roving and spinning steps to produce a PBO / technola blended yarn. The twist coefficient of the obtained blended yarn is 3.
5th was 20th. From the obtained spun yarn, a plain woven fabric having a weaving density of 90 warps / inch and 50 wefts / inch was produced using a rapier loom. The basis weight of the obtained woven fabric was 175 g / m2 and the thickness was 0.37 mm.
Table 1 shows the results of evaluating the light resistance of the obtained plain fabric.

Comparative Example 1 Polyparaphenylene benzobisoxazole 14.0 having an intrinsic viscosity of 24.4 dL / g measured with a methanesulfonic acid solution at 30 ° C., obtained by the method described in US Pat. No. 4,453,693. A spinning dope consisting of polyphosphoric acid with a weight percent and a phosphorus pentoxide content of 83.17% was used for spinning. The dope is passed through a metal mesh filter medium, and then kneaded and defoamed with a kneading device consisting of two axes, and then the pressure is increased, and the temperature of the polymer solution is maintained at 170 ° C.
After spinning at 170 ° C. from a spinneret having 160 holes and cooling the discharged yarn using cooling air at a temperature of 60 ° C., it is wound around a godet roll to give a spinning speed, and the temperature is adjusted to 20 ±
Extraction (coagulation) consisting of 20% phosphoric acid aqueous solution maintained at 2 ° C
Introduced into the bath. Subsequently, the yarn was washed with ion-exchanged water in the second extraction bath, immersed in a 0.1 mol / L sodium hydroxide solution for neutralization, and then dried at 120 ° C. for 120 seconds. Using the obtained fibers, a PBO / Technola blend spun fabric of the same standard was produced in the same manner as in the example. The basis weight of the obtained fabric is 170 g / m ² ,
The thickness was 0.36 mm. Table 1 also shows the results of the light resistance evaluation.

[0030]

[Table 1]

From Table 1 above, it can be seen that the molded article of the present invention has a conventional heat resistance.
It turns out that it shows extremely excellent light resistance as compared with the flame retardant fabric.

[0032]

According to the present invention, a heat-resistant and flame-retardant woven knitted material containing polybenzazole fiber having good light resistance can be industrially easily produced, and therefore, industrial materials, particularly heat-resistant clothing and fire-fighting clothing materials. It has a great effect of improving the practicality and expanding the field of use.

[Brief description of the drawings]

FIG. 1 is a specular reflectance spectrum. (1) The case without the light-proofing agent treatment. (2) is the case where the light-resistant agent treatment was performed.

Claims (5)

[Claims] 1. A method according to claim 1, wherein at least a part of the polybenzazole fiber is provided with a light-resistant agent having a regular reflectance of 30% or less in a region of 30% or more in a wavelength range of 450 nm to 700 nm. Heat-resistant and flame-retardant woven knitted fabric with excellent light resistance. 2. A light-fast agent having a wavelength of 450 nm to 700 nm.
The regular reflectance of the fiber is 2
The heat-resistant and flame-retardant woven knitted fabric according to claim 1, wherein the content is 0% or less. 3. The heat-resistant and flame-retardant woven knitted fabric according to claim 1, wherein the light-proofing agent is an oxidation dye compound. 4. The heat-resistant and flame-retardant woven knitted fabric according to claim 1, wherein the light-resistant agent is a compound composed of an aromatic amine or a compound composed of phenols. 5. The heat-resistant and flame-retardant woven knitted fabric according to claim 1, wherein the light-resistant agent is provided in an amount of 0.01 to 20.0% by weight based on the fiber.