JP7633129B2 - Woven fabrics and heat protective clothing - Google Patents

Description

The present invention relates to woven and knitted fabrics and heat protective clothing that are flame retardant, heat insulating, and comfortable.

Knitted fabrics have excellent elasticity and are therefore used as sportswear and workwear. For heat protection purposes, knitted fabrics that use flame-retardant fibers and have excellent heat-shielding properties have also been proposed (see, for example, Patent Documents 1 to 4).

However, while these technologies have excellent heat insulation properties, they also have high heat retention properties, which means that heat does not easily escape when worn, making them less comfortable and increasing the risk of heat stroke. In particular, the international standard ISO21942 has been established in recent years for the so-called station wear worn by firefighters under their firefighting suits, but the requirements include thermal resistance to evaluate heat loss from the body and water vapor transmission resistance, and the above-mentioned prior art was not sufficient to meet these requirements.

JP 2010-242239 A JP 2019-090120 A JP 2019-127657 A JP 2020-193422 A

The present invention has been made in consideration of the above background, and its purpose is to provide woven or knitted fabrics and heat protective clothing that are excellent in flame retardancy, heat insulation, and comfort.

The inventors have completed this invention through extensive research to achieve the above objectives.

Thus, according to the present invention, there is provided "a woven or knitted fabric comprising a spun yarn in which a meta-type wholly aromatic polyamide fiber and a para-type wholly aromatic polyamide are blended, the woven or knitted fabric being characterized in that the fabric has a basis weight of 100 to 200 g/ ^m2 and a thickness of 0.6 to 1.1 mm under a load of ⁷ g/cm2."

In this case, it is preferable to satisfy all of the following requirements (1) to (8).
(1) In the flame resistance test specified in ISO 15025 Procedure A, all of the following are satisfied:
a) No flames b) No flaming or molten falling objects c) No holes larger than 5 mm d) Afterglow lasts 2 seconds or less e) Afterglow lasts 2 seconds or less (2) In the heat resistance test specified in ISO 17493, all of the following are met when exposed to 260-265°C for 5 minutes.
a) No melting; b) No dripping; c) No flame ignition; d) Shrinkage rate of less than 10%. (3) In the flame exposure test specified in ISO 9151, HTI ₂₄ is 4 seconds or more.
(4) In a radiant heat exposure test with a heat flux of 20 kW/ ^m2 specified in ISO 6942 METHOD B, RHTI ₂₄ is 7 seconds or more.
(5) The dimensional change after five washes as specified in ISO 5077 is 8% or less.
(6) The bursting strength as specified in ISO 13938-1 or ISO 13938-2 exceeds 100 kPa for a 50 ^cm2 test piece, and exceeds 200 kPa for a 7.3 ^cm2 test piece.
(7) The thermal resistance value as defined in ISO 11092 is less than 0.055 m ² K/W.
(8) The water vapor transmission resistance value as defined in ISO 11092 is less than 7 m ² Pa/W.

The present invention provides woven and knitted fabrics and heat protective clothing that are flame retardant, heat insulating, and comfortable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. First, the spun yarn contains meta-type wholly aromatic polyamide fibers and para-type wholly aromatic polyamide fibers, which are blended together.
Here, the meta-type wholly aromatic polyamide fiber is a fiber made of a polymer in which 85 mol % or more of the repeating units are m-phenylene isophthalamide. Such a meta-type wholly aromatic polyamide may be a copolymer containing a third component in an amount of less than 15 mol %.

Such meta-type wholly aromatic polyamides can be produced by the conventionally known interfacial polymerization method, and the degree of polymerization of the polymer is preferably in the range of 1.3 to 1.9 dl/g intrinsic viscosity (I.V.) measured in an N-methyl-2-pyrrolidone solution with a concentration of 0.5 g/100 ml.

The meta-type wholly aromatic polyamide may contain an alkylbenzenesulfonate onium salt. Preferred examples of the alkylbenzenesulfonate onium salt include tetrabutyl phosphonium salt of hexylbenzenesulfonate, tributyl benzyl phosphonium salt of hexylbenzenesulfonate, tetraphenyl phosphonium salt of dodecylbenzenesulfonate, tributyl tetradecyl phosphonium salt of dodecylbenzenesulfonate, tetrabutyl phosphonium salt of dodecylbenzenesulfonate, and tributyl benzyl ammonium salt of dodecylbenzenesulfonate. Among these, tetrabutyl phosphonium salt of dodecylbenzenesulfonate and tributyl benzyl ammonium salt of dodecylbenzenesulfonate are particularly preferred because they are easily available, have good thermal stability, and have high solubility in N-methyl-2-pyrrolidone.

The content of the alkylbenzenesulfonate onium salt is preferably 2.5 mol % or more, and more preferably 3.0 to 7.0 mol %, relative to the poly-m-phenylene isophthalamide in order to obtain a sufficient effect of improving dyeability.

As a method for mixing poly-m-phenylene isophthalamide and an alkylbenzene sulfonate onium salt, any of the following methods may be used: mixing and dissolving poly-m-phenylene isophthalamide in a solvent, and then dissolving the alkylbenzene sulfonate onium salt in the solvent. The dope thus obtained is formed into fibers by a conventionally known method.

For the purpose of improving dyeability and resistance to fading, the polymer used for the meta-type wholly aromatic polyamide fiber may be copolymerized in an aromatic polyamide skeleton containing a repeating structural unit represented by the following formula (1) with an aromatic diamine component different from the main structural unit of the repeating structure or an aromatic dicarboxylic acid halide component as a third component in an amount of 1 to 10 mol % relative to the total amount of the repeating structural units of the aromatic polyamide.
-(NH-Ar1-NH-CO-Ar1-CO)-...Formula (1)
Here, Ar1 is a divalent aromatic group having a linking group in a meta-coordinated or parallel axial direction other than that.

It is also possible to copolymerize it as a third component. Specific examples of aromatic diamines shown in formulas (2) and (3) include p-phenylenediamine, chlorophenylenediamine, methylphenylenediamine, acetylphenylenediamine, aminoanisidine, benzidine, bis(aminophenyl)ether, bis(aminophenyl)sulfone, diaminobenzanilide, diaminoazobenzene, etc. Specific examples of aromatic dicarboxylic acid dichlorides shown in formulas (4) and (5) include terephthalic acid chloride, 1,4-naphthalenedicarboxylic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, 4,4'-biphenyldicarboxylic acid chloride, 5-chloroisophthalic acid chloride, 5-methoxyisophthalic acid chloride, bis(chlorocarbonylphenyl)ether, etc.

H ₂ N-Ar2-NH ₂ ...Formula (2)
H ₂ N-Ar2-Y-Ar2-NH ₂ ...Formula (3)
XOC-Ar3-COX...Formula (4)
XOC-Ar3-Y-Ar3-COX...Formula (5)
Here, Ar2 is a divalent aromatic group different from Ar1, Ar3 is a divalent aromatic group different from Ar1, Y is at least one atom or functional group selected from the group consisting of an oxygen atom, a sulfur atom, and an alkylene group, and X represents a halogen atom.

The degree of crystallinity of meta-type wholly aromatic polyamide fibers is preferably 5 to 35%, since it has good dye exhaustion properties and can be easily adjusted to the desired color with less dye or under weak dyeing conditions. Furthermore, it is more preferable that the degree of crystallinity is 15 to 25%, since it is less likely for the dye to be unevenly distributed on the surface, it has high resistance to discoloration, and it ensures the dimensional stability required for practical use.

The amount of residual solvent in meta-type wholly aromatic polyamide fibers is preferably 0.1% by mass or less (more preferably 0.001 to 0.1% by mass) so as not to impair the excellent flame retardant performance of meta-type wholly aromatic polyamide fibers.

As such meta-type wholly aromatic polyamide fibers, in order to obtain excellent light fastness, it is preferable to use dope-dyed meta-type wholly aromatic polyamide fibers as described in WO 2013/061901.

That is, examples of pigments that can be used in the present invention include organic pigments such as azo pigments, phthalocyanine pigments, perinone pigments, perylene pigments, and anthraquinone pigments, as well as inorganic pigments such as carbon black, ultramarine blue, red iron oxide, titanium oxide, and iron oxide, but are not limited to these.

Methods of mixing the meta-type wholly aromatic polyamide and the pigment include, but are not limited to, a method of preparing an amide-type solvent slurry in which the pigment is uniformly dispersed in an amide-type solvent, and adding the amide-type solvent slurry to a solution in which the meta-type wholly aromatic polyamide is dissolved in an amide-type solvent, or a method of directly adding a pigment powder to a solution in which the meta-type wholly aromatic polyamide is dissolved in an amide-type solvent.

The amount of pigment to be added is 10.0% by mass or less, preferably 5.0% by mass or less, based on the meta-type wholly aromatic polyamide. If more than 10.0% by mass is added, the physical properties of the resulting fiber may be degraded.

The meta-type wholly aromatic polyamide fibers as described above can be produced by the following method, and in particular, the crystallinity and the amount of remaining solvent can be adjusted to the above-mentioned ranges by the method described below.
The polymerization method for the meta-type wholly aromatic polyamide polymer is not particularly limited, and for example, the solution polymerization method and interfacial polymerization method described in JP-B-35-14399, US Pat. No. 3,360,595, JP-B-47-10863, etc. may be used.

The spinning solution is not particularly limited, but may be an amide-based solvent solution containing an aromatic copolyamide polymer obtained by the above-mentioned solution polymerization or interfacial polymerization, or the polymer isolated from the above-mentioned polymerization solution and dissolved in an amide-based solvent.

Examples of amide solvents used here include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylsulfoxide, with N,N-dimethylacetamide being particularly preferred.

The copolymerized aromatic polyamide polymer solution obtained as described above is preferably stabilized by further containing an alkali metal salt or an alkaline earth metal salt, which allows use at a higher concentration and at a lower temperature. The alkali metal salt and alkaline earth metal salt are preferably 1% by mass or less, more preferably 0.1% by mass or less, based on the total mass of the polymer solution. In this case, it is preferable to contain a flame retardant such as the one described above.

In the spinning and coagulation process, the spinning solution obtained above (meta-type wholly aromatic polyamide polymer solution or original dyed meta-type wholly aromatic polyamide polymer solution) is spun into a coagulation solution and coagulated.

The spinning device is not particularly limited, and a conventionally known wet spinning device can be used. In addition, as long as it can perform stable wet spinning, there is no need to particularly limit the number of spinning holes, the arrangement state, the hole shape, etc. of the spinneret, and for example, a multi-hole spinneret for staple fibers having 1,000 to 30,000 holes and a spinning hole diameter of 0.05 to 0.2 mm may be used.
The temperature of the spinning solution (meta-type wholly aromatic polyamide polymer solution) when it is spun out from the spinneret is suitably in the range of 20 to 90°C.

The coagulation bath used to obtain the fibers is an aqueous solution of an amide solvent, preferably NMP, containing substantially no inorganic salts and having a concentration of 45 to 60% by mass, with the bath temperature in the range of 10 to 50°C. If the concentration of the amide solvent (preferably NMP) is less than 45% by mass, the skin will be thick, which may reduce the cleaning efficiency in the cleaning process and make it difficult to reduce the amount of solvent remaining in the fibers. On the other hand, if the concentration of the amide solvent (preferably NMP) exceeds 60% by mass, uniform coagulation cannot be achieved all the way to the inside of the fibers, and therefore it is also difficult to reduce the amount of solvent remaining in the fibers. The appropriate immersion time for the fibers in the coagulation bath is in the range of 0.1 to 30 seconds.

Subsequently, the film is stretched at a stretch ratio of 3 to 4 in a plastic stretching bath containing an amide solvent, preferably an aqueous solution containing NMP at a concentration of 45 to 60% by mass, and the bath temperature is set to a range of 10 to 50° C. After stretching, the film is thoroughly washed by passing it through an aqueous solution containing NMP at a concentration of 20 to 40% by mass at 10 to 30° C., and then through a warm water bath at 50 to 70° C.
The washed fibers are subjected to a dry heat treatment at a temperature of 270 to 290° C., whereby meta-type wholly aromatic aramid fibers that satisfy the above ranges of crystallinity and residual solvent amount can be obtained.

In the meta-type wholly aromatic aramid fiber, the fiber may be a long fiber (multifilament) or a short fiber. In particular, short fibers with a fiber length of 25 to 200 mm are preferred for blending with other fibers. In addition, the single fiber fineness is preferably in the range of 1 to 5 dtex.

Furthermore, para-type wholly aromatic polyamide fibers are more preferably paraphenylene terephthalamide fibers or coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers.

Meta-type wholly aromatic polyamides alone may cause holes to form during the flame resistance test specified in ISO 15025 Procedure A. Para-type wholly aromatic polyamides alone may cause flame ignition.

The blend ratio of meta-type wholly aromatic polyamide fiber and para-type wholly aromatic polyamide fiber is preferably 95 to 40% by weight of meta-type wholly aromatic polyamide fiber based on the total weight of meta-type wholly aromatic polyamide fiber and para-type wholly aromatic polyamide fiber.

The blended yarn may further contain other synthetic fibers such as conductive fibers. In this case, the conductive fibers are preferably fibers that contain at least one of carbon black, conductive titanium oxide, conductive whiskers, and carbon nanotubes as the conductor of the conductive portion of the conductive fibers.

The conductive fiber may be in a form in which the entire fiber is made of conductive parts, or the non-conductive and conductive parts may have a cross-sectional shape such as core-sheath, sandwich, or eccentric. The resin forming the conductive and non-conductive parts is not particularly limited as long as it has fiber-forming properties. Specific examples of nylon resins include nylon 6, nylon 11, nylon 12, and nylon 66. Examples of polyester resins include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexane terephthalate, and copolymers thereof, as well as those in which part of the acid component (terephthalic acid) is replaced with isophthalic acid.

Commercially available conductive fibers include "METALIAN" (trade name) manufactured by Teijin Limited, "MEGANA" (trade name) manufactured by Unitika Fibers, "LUANA" (trade name) manufactured by Toray Industries, Inc., and "CLACARBO" (trade name) manufactured by Kuraray Co., Ltd. In particular, core-sheath type composite fibers in which a conductive component is arranged in the sheath are preferred. As such a core-sheath type composite fiber, "NO SHOCK (registered trademark)" manufactured by Solcia Corporation is preferred.

The yarns constituting the woven or knitted fabric of the present invention are preferably spun yarns in which the above-mentioned fibers are blended. In this case, due to restrictions on basis weight and thickness, it is preferable to use spun yarns of British cotton count 40 to 80, either alone or in combination. The spun yarns may be used as single yarns or after twisting, but in the case of two-ply yarns, it is preferable that they are no thicker than the equivalent of count 20.

The woven or knitted fabric of the present invention is preferably made of the above-mentioned blended yarn, but it is preferable to use a 60-80 count spun yarn made of 100% meta-type fully aromatic polyamide, with the upper limit of 35% of the entire woven or knitted fabric, as a means of adjusting the basis weight.

In the woven or knitted fabric of the present invention, it is important that the basis weight is 100 to 200 g/m ^2. If it is less than 100 g/m ² , there is a risk that sufficient burst strength, heat insulation properties as typified by ISO 9151 and ISO 6942 Method B, and flame resistance may not be obtained, and if it exceeds 200 g/m ² , there is a risk that heat dissipation properties as typified by thermal resistance and water vapor transmission resistance may be impaired.

It is also important that the woven or knitted fabric of the present invention has a thickness of 0.6 to 1.1 mm under a load of 7 g/ ^cm2 . If it is less than 0.6 mm, the heat shielding properties may be impaired, and if it exceeds 1.1 mm, the heat dissipation properties may be impaired. In order to achieve both heat shielding properties and heat dissipation properties, it is preferable that the air permeability is within the range of 160 to 350 ^cm2 / ^cm2 /sec (more preferably 200 to 260 ^cm3 / ^cm2 ·sec).

The woven or knitted fabric of the present invention can be woven or knitted by a conventional method. Either a circular knit structure or a warp knit structure may be used. In the case of circular knit, single knits such as plain stitch, pearl knit, and rib knit are preferred, while in the case of double knit warp knits such as smooth knit, denbi, double denbi, half, and reverse half are preferred. In particular, to increase thermal conductivity, knits with as few air layers, i.e., gaps or irregularities as possible are more preferred. Knit structures that do not include tucks in the structure are preferred. Due to restrictions on basis weight and thickness, a gauge number of 22G (gauge) or less is preferred.

It is preferable to color such fabrics. In this case, the coloring method can be a known method. That is, the wholly aromatic polyamide fiber (aramid fiber) may be dyed either in its original form or with a carrier agent.

Since the woven or knitted fabric of the present invention has the above-mentioned configuration, it is excellent in terms of comfort such as flame retardancy, heat shielding property, heat dissipation property, etc. In this regard, it is preferable that the fabric satisfies all of the following in the flame resistance test specified in ISO 15025 Procedure A.
a) No flame b) No flaming or molten falling objects c) No holes larger than 5 mm d) Afterglow for 2 seconds or less e) Afterglow for 2 seconds or less

In addition, in the heat resistance test specified in ISO 17493, it is preferable that all of the following be satisfied when exposed to 260 to 265° C. for 5 minutes.
a) No melting b) No dripping c) No flames d) Shrinkage rate is less than 10%

In addition, in the flame exposure test specified in ISO 9151, HTI ₂₄ is preferably 4 seconds or more. In the radiant heat exposure test with a heat flux of 20 kW/m ² specified in ISO 6942 METHOD B, RHTI ₂₄ is preferably 7 seconds or more. In addition, the dimensional change before and after five washes specified in ISO 5077 is preferably 8% or less. In addition, the burst strength specified in ISO 13938-1 or ISO 13938-2 is preferably more than 100 kPa for a test piece of 50 cm ² , and more than 200 kPa for a test piece of 7.3 cm ^2. In addition, the heat resistance value specified in ISO 11092 is preferably less than 0.055 ^{m 2} K/W. In addition, the water vapor transmission resistance value specified in ISO 11092 is preferably less than 7 m ² Pa/W.

Next, the heat protective clothing of the present invention is heat protective clothing made using the above-mentioned woven or knitted fabric. Specific examples include station wear, or work clothes, worn by firefighters under their fire-retardant clothing. Since such heat protective clothing uses the above-mentioned woven or knitted fabric, it has excellent comfort, including flame retardancy, heat insulation, and heat dissipation.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
(1) Basis Weight: Measured according to JIS L 1096 A method.
(2) Thickness: Measurement was carried out with a load of 7 g/ ^cm2 .
(3) Air Permeability: Measured according to JIS L1096-1990 Air Permeability Method A (Fragile method).
(4) Flame Retardance Test: Measurement was carried out based on ISO 15025 Procedure A.
(5) Heat Resistance Test In the heat resistance test specified in ISO 17493, measurements were performed under the conditions of exposure at 260 to 265° C. for 5 minutes.
(6) Flame Exposure Test Measurement was carried out based on ISO9151.
(7) Radiant heat exposure test: Measurement was performed based on ISO 6942 Method B at a heat flux of 20 kW/ ^m2 .
(8) Dimensional change after washing: Measured before and after five washings according to ISO 5077.
(9) Burst strength: Measured using a 7.3 ^cm2 test piece based on ISO 13938-1.
(10) Thermal resistance value: Measured based on ISO 11092.
(11) Water Vapor Permeation Resistance Value: Measured based on ISO 11092.

The following materials were used in the examples and comparative examples.
(Meta-type fully aromatic polyamide dyed staple fiber)
"Conex" (registered trademark) manufactured by Teijin Limited, average single fiber fineness 2.2 dtex, fiber length 51 mm
(Meta-type fully aromatic polyamide short fibers)
"Conex" (registered trademark) manufactured by Teijin Limited, average single fiber fineness 2.2 dtex, fiber length 51 mm
(Para-type wholly aromatic polyamide staple fiber)
"Technora" (registered trademark), manufactured by Teijin Limited, average single fiber fineness 1.7 dtex, fiber length 51 mm
(No. 40 dope dyed blended staple fiber)
95% meta-type wholly aromatic polyamide spun-dyed staple fibers and 5% para-type wholly aromatic polyamide staple fibers were ring-spun in a conventional manner to obtain a single yarn having a British cotton count of 40.
(No. 40 unbleached staple fiber)
100% meta-type wholly aromatic polyamide staple fibers were ring spun in a conventional manner to obtain single yarns having a British cotton count of 40.
(No. 60 unbleached staple fiber)
100% meta-type wholly aromatic polyamide staple fibers were ring spun in a conventional manner to obtain single yarns of British cotton count 60.
(40-count two-ply yarn dyed blended staple fiber)
British cotton number 40 dope-dyed staple fibers were twisted into two-ply yarn in the S direction at 19.8T/2, 54 cm, and steam set at 100° C. for 30 minutes.
(Circular knitting machine)
Circular knitting machines with 20, 22 and 28 gauge and a 33 inch diameter knitting machine were used.
(Warp knitting machine)
A 28 gauge, 2 bar tricot machine was used.

[Examples 1 to 3, Comparative Examples 1 to 7]
Knitted fabrics were obtained with the knitting type, knitting structure, yarn usage, and gauge shown in Table 1. The evaluation results are shown in Table 1.

The present invention provides woven and knitted fabrics and heat protective clothing that are excellent in terms of comfort, such as flame retardancy, heat insulation, and heat dissipation, and is of great industrial value.

Claims (2)

The woven or knitted fabric is a circular knitted fabric containing a spun yarn in which meta-type wholly aromatic polyamide fiber and para-type wholly aromatic polyamide fiber are blended, the woven or knitted fabric having a basis weight of 100 to 163 g/m ² , a thickness of 0.6 to 1.1 mm under a load of 7 g/cm ² , and an air permeability of 160 to 350 cm ³ /cm ² /sec , and satisfying all of the following requirements (1) to (8) :
(1) In the flame resistance test specified in ISO 15025 Procedure A,
Satisfy all of the following:
a) No flame
b) No flaming or molten falling objects
c) No holes larger than 5 mm
d) Residual light lasts for 2 seconds or less
e) Afterflame lasts less than 2 seconds
(2) In the heat resistance test specified in ISO 17493, the material satisfies all of the following requirements when exposed to 260-265°C for 5 minutes.
a) Does not melt
b) No dripping
c) No flame
d) Shrinkage rate is less than 10%
(3) In the flame exposure test specified in ISO 9151, HTI24 is 4 seconds or more.
(4) According to ISO 6942 METHOD B, the heat flux is 20 kW/ ^m2.
In a radiant heat exposure test, RHTI24 is 7 seconds or more.
(5) The dimensional change after five washes as specified in ISO 5077 is 8% or less.
(6) The bursting strength as specified in ISO 13938-1 or ISO 13938-2 exceeds 100 kPa for a 50 cm2 test piece, and exceeds 200 kPa for a 7.3 cm2 ^test piece ^.
(7) The thermal resistance value as defined in ISO 11092 is less than 0.055 m ² K/W.
(8) The water vapor transmission resistance value as defined in ISO 11092 is less than 7 m ² Pa/W. A heat protective garment comprising the woven or knitted fabric of claim 1 .