Flame-retardant fabric, and flame-retardant work clothes comprising same

Abstract

The present invention relates to a flame-retardant fabric including a modacrylic fiber A, a modacrylic fiber B, and a cellulose fiber. The modacrylic fiber A includes a compound containing tin and zinc, and is substantially free of a magnesium compound, and the modacrylic fiber B comprises a magnesium compound, and is substantially free of a compound containing tin and zinc. The flame-retardant fabric comprises the compound containing tin and zinc derived from the modacrylic fiber A in an amount of 2.0 mass% or more, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more after a flammability test according to ISO 15025.

Description

Technical Field

[0001] The present invention relates to a flame-retardant fabric including modacrylic fibers and cellulose fibers and a flame-retardant work clothing including the flame-retardant fabric.Background Art

[0002] Halogen-containing fibers e.g., a modacrylic fiber is combined with other fibers e.g., a cellulose fiber, and is generally and especially used suitably in work clothing. On the other hand, halogen-containing fibers e.g., a modacrylic fiber has generally been made flame retardancy by adding about 1 to about 50 parts by mass of a antimony compound as flame retardant (for example, Patent Document 1). However, since the antimony compound may affect the environment and the human body, flame retardants other than the antimony compound are being considered. For example, Patent Document 2 proposes incorporating tin compounds to halogen-containing fibers as compounds that impart flame retardancy, and the halogen-containing fibers used together with cellulose fibers.Citation ListPatent Documents

[0003] Patent Document 1: JP H4(1992)-18050A Patent Document 2: JP H10(1998)-001822A Disclosure of InventionProblems to be Solved by the Invention

[0004] However, when a zinc stannate compound is used as a flame retardant, flame retardancy of the modacrylic fiber is inferior to when an antimony compound is used as a flame retardant.

[0005] To address the above-described conventional problem, the present invention provides a flame-retardant fabric with enhanced flame retardancy while being environmentally friendly, and a flame-retardant work clothing including the flame-retardant fabric.Solution to Problem

[0006] One or more embodiments of the present invention relate to a flame-retardant fabric including: a modacrylic fiber A; a modacrylic fiber B; and a cellulose fiber, where the modacrylic fiber A includes a compound containing tin and zinc, and is substantially free of a magnesium compound, the modacrylic fiber B includes a magnesium compound, and is substantially free of a compound containing tin and zinc, the flame-retardant fabric includes the compound containing tin and zinc derived from the modacrylic fiber A in an amount of 2.0 mass% or more, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more after a flammability test according to ISO 15025.

[0007] One or more embodiments of the present invention relate to a flame-retardant work clothing including the flame-retardant fabric.Effects of the Invention

[0008] The present invention can provide a flame-retardant fabric with enhanced flame retardancy while being environmentally friendly and a flame-retardant work clothing including the flame-retardant fabric.Description of the Invention

[0009] The inventors of the present invention have conducted in-depth studies to improve flame retardancy of a flame-retardant fabric that includes a modacrylic fiber and a cellulose fiber while considering environmentally friendly. As a result, the inventors found that by including a modacrylic fiber A that includes a compound containing tin and zinc, and is substantially free of a magnesium compound, a modacrylic fiber B that includes a magnesium compound, and is substantially free of a compound containing tin and zinc, and a cellulose fiber to the fabric, as well as setting the amount of the compound containing tin and zinc in the fabric within specified range, the fabric can exhibit excellent flame retardancy (gas-phase flame retardancy and solid-phase flame retardancy).

[0010] In particular, surprisingly, the inventors of the present invention have found that when a modacrylic fiber containing a compound containing tin and zinc and a magnesium compound are used in combination with a cellulose fiber, they are less flame retardancy. However, when a cellulose fiber is used in combination with a modacrylic fiber A, that contains a compound containing tin and zinc and is substantially free of magnesium, and a modacrylic fiber B, that contains a magnesium compound and is substantially free of tin and zinc, the synergistic effect of the gas-phase flame retardancy of the compound containing tin and zinc in the modacrylic fiber A and the solid-phase flame retardancy of the magnesium compound in the modacrylic fiber B improves the flame retardancy of the fabric, resulting in extremely high flame retardancy, specifically, the afterflame and afterglow time are shortened, and a foamed char layer is formed, in a flammability test used to evaluate flame retardancy standards for work clothing, such as a flammability test according to ISO 15025. If the thickness of the char layer of the flame-retardant fabric after a flammability test according to ISO 15025 is 4.0 mm or more, a barrier layer is formed by the char layer, which prevents the spread of flames to the back surface, and the work clothing using the flame-retardant fabric have good protection properties for the human body.

[0011] In this specification, when a numerical range is shown using "to", that includes the values at both ends (i.e., the upper limit and the lower limit). For example, a numerical range "A to B" is a range that includes A and B, which are the values at the two ends of the range, and is the same as "A or more and B or less". Also, when a plurality of numerical ranges is described in this specification, numerical ranges obtained by using the upper limits and the lower limits of the different numerical ranges in combination as appropriate are included.Flame-retardant fabric

[0012] In one or more embodiments of the present invention, the flame-retardant fabric contains the compound containing tin and zinc in an amount of 2.0 mass% or more, preferably 2.2 mass% or more, more preferably 2.4 mass% or more, and still more preferably 2.6 mass% or more. The compound containing tin and zinc in the flame-retardant fabric is derived from the modacrylic fiber A, and when the content of the compound containing tin and zinc is within to above mentioned range, the flame retardancy, especially the gas-phase flame retardancy of the flame-retardant fabric is improved. The upper limit of the content of the compound containing tin and zinc in the flame-retardant fabric is not particularly limited, for example, from the viewpoint of spinnability of the modacrylic fiber A, it is preferably 12 mass% or less, more preferably 10 mass% or less, still more preferably 8.0 mass% or less, and yet more preferably 6.0 mass% or less. More specifically, the flame-retardant fabric desirably contains the compound containing tin and zinc in an amount of 2.0 to 12 mass%, 2.2 to 10 mass%, 2.4 to 8.0 mass%, or 2.6 to 6.0 mass%.

[0013] The modacrylic fiber A contains a compound containing tin and zinc, and is substantially free of a magnesium compound. In this specification, the wording "substantially free of a magnesium compound" means that a magnesium compound is not added to a fiber or a fabric on purpose, and accordingly, the state where a magnesium compound is contained as a contaminant or the like is considered as "substantially free of a magnesium compound". When the modacrylic fiber A is used together with the modacrylic fiber B, a synergistic effect is exhibited, making it possible to improve both the gas-phase flame retardancy and the solid-phase flame retardancy.

[0014] The modacrylic fiber A is not particularly limited, and a fiber containing a modacrylic polymer and a compound containing tin and zinc can be used as long as the content of the compound containing tin and zinc in the flame-retardant fabric satisfy the above-mentioned range. The modacrylic fiber A preferably contains the compound containing tin and zinc inside the fiber from the viewpoint of flame retardant washing durability.

[0015] The modacrylic fiber A preferably contains the compound containing tin and zinc in an amount of 5.5 to 25 parts by mass, more preferably 6 to 20 parts by mass, still more preferably 7 to 18 parts by mass, and particular more preferably 8 to 16 parts by mass, with respect to 100 parts by mass of the modacrylic polymer, from the viewpoint of flame retardancy, spinnability, fiber strength, and fabric strength.

[0016] The modacrylic fiber A preferably contains the compound containing tin and zinc in an amount of 5 mass% or more, more preferably 6 mass% or more, still more preferably 7 mass% or more, and particular more preferably 8 mass% or more, from the viewpoint of the flame retardancy, and especially further improving both the gas-phase flame retardancy and the solid-phase flame retardancy as a result of synergistic effect with the modacrylic fiber B. In addition, the modacrylic fiber A preferably contains the compound containing tin and zinc in an amount of 20 mass% or less, more preferably 18 mass% or less, still more preferably 16 mass% or less, and particular more preferably 14 mass% or less, from the viewpoint of fiber strength and fabric strength. More specifically, the modacrylic fiber A desirably contains the compound containing tin and zinc in an amount of 5 to 20 mass%, 6 to 18 mass%, 7 to 16 mass%, or 8 to 14 mass%. In this specification, the content of the compound containing tin and zinc in a modacrylic fiber may be measured by fluorescence X-ray analysis.

[0017] The compound containing tin and zinc is not particularly limited, and from the viewpoint of general purpose, for example, any zinc stannate compound may be used. The zinc stannate compound may be zinc stannate (ZnSnO 3 ) or zinc hydroxystannate (ZnSn(OH) 6 ). Among them, for example, zinc hydroxystannate is preferable, from the viewpoint of further improving flame retardancy of the modacrylic fiber, the fabric, and the work clothing.

[0018] A median particle size D50 of the compound containing tin and zinc is not particularly limited, for example, from the viewpoint of spinnability and fiber strength, it is preferably 3.0 µm or less, more preferably 2.5 µm or less, and still more preferably 2.0 µm or less. There is no particular limitation on the lower limit of the median particle size D50 of the compound containing tin and zinc, for example, from the viewpoint of the handleability, it may be 0.1 µm or more, and from the viewpoint of flame retardancy, it may be 0.5 µm or more, 0.6 µm or more, or 0.7 µm or more. More specifically, the median particle size D50 of the compound containing tin and zinc may be 0.1 to 3.0 µm, 0.5 to 2.5 µm, 0.6 to 2.0 µm, or 0.7 to 2.0 µm. In this specification, the median particle size D50 of a compound may be measured by a laser diffraction / scattering method or a dynamic light scattering method using a dispersion (liquid dispersion) obtained by dispersing the compound in water or an organic solvent.

[0019] A modacrylic polymer containing acrylonitrile, a halogen-containing monomer, and another copolymerizable monomer may be used as the modacrylic polymer. The modacrylic polymer is not particularly limited, and for example, from the viewpoint of further improving the heat resistance and the flame retardancy, the modacrylic polymer preferably contains acrylonitrile in an amount of 30 to 85 mass%, the halogen-containing monomer in an amount of 15 to 70 mass%, and the other copolymerizable monomer in an amount of 0 to 3 mass%, more preferably contains acrylonitrile in an amount of 35 to 75 mass%, the halogen-containing monomer in an amount of 25 to 65 mass%, and the other copolymerizable monomer in an amount of 0 to 3 mass%, and still more preferably contains acrylonitrile in an amount of 40 to 70 mass%, the halogen-containing monomer in an amount of 30 to 60 mass%, and the other copolymerizable monomer in an amount of 0 to 3 mass%.

[0020] Examples of the halogen-containing monomer include a halogen-containing vinyl monomer such as vinyl chloride, vinyl bromide, and the like, and a halogen-containing vinylidene monomer such as vinylidene chloride, vinylidene bromide, and the like. The halogen-containing monomer may be used alone or in combination of two or more. The halogen-containing monomer is preferably the halogen-containing vinylidene monomer from the viewpoint of the heat resistance, and vinylidene chloride is more preferred from the viewpoint of the synergy effect in the flame retardancy with the compound containing tin and zinc.

[0021] The other copolymerizable monomer is not particularly limited as long as they are copolymerizable with acrylonitrile. Examples of the other copolymerizable monomer include unsaturated carboxylic acids typified by acrylic acids and methacrylic acids, as well as salts thereof; esters of unsaturated carboxylic acids, typified by methacrylic esters (e.g. methyl methacrylate), glycidyl methacrylate and the like; vinyl esters typified by vinyl acetate and vinyl butyrate; and sulfonic acid group-containing monomers. Examples of the sulfonic acid group-containing monomers include, but not particularly limited to, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, isoprenesulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid, as well as metal salts, such as sodium salts, and amine salts thereof. The other copolymerizable vinyl monomer may be used alone, or two or more of them may be used in combination. Among them, the sulfonic acid group-containing monomers may be used from the viewpoint of improving dye-affinity.

[0022] The modacrylic fiber A preferably contains the modacrylic polymer in an amount of 80 to 95 mass% and the compound containing tin and zinc in an amount of 5 to 20 mass%, more preferably contains the modacrylic polymer in an amount of 82 to 94 mass% and the compound containing tin and zinc in an amount of 6 to 18 mass%, still more preferably contains the modacrylic polymer in an amount of 83 to 93 mass% and the compound containing tin and zinc in an amount of 7 to 16 mass%, and yet more preferably contains the modacrylic polymer in an amount of 86 to 92 mass% and the compound containing tin and zinc in an amount of 8 to 14 mass%. The modacrylic fiber A may contain one or more other additives e.g., an antistatic agent, a thermal coloration inhibitor, a light resistance improver, a whiteness improver, a devitrification inhibitor, and a colorant, as needed. In the modacrylic fiber A, the other additives may be used in an amount of 10 mass% or less, 5 mass% or less, or 1 mass% or less.

[0023] The modacrylic fiber A may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use.. The single fiber fineness of the modacrylic fiber A, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the modacrylic fiber A is selected as appropriate depending on the intended use and the like of the fabric and the work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber (filament fiber) can be used.

[0024] The single fiber strength of the modacrylic fibers A is preferably 1.0 to 4.0 cN / dtex, and more preferably 1.5 to 3.5 cN / dtex, from the viewpoint of durability. Also, the elongation at break of the modacrylic fibers A is preferably 15 to 40%, and more preferably 20 to 30%, from the viewpoint of practicality. In this specification, the single fiber strength and elongation of a fiber may be measured according to JIS L 1013:2010 or JIS L 1015:2010.

[0025] The modacrylic fiber A can preferably be produced by spinning a composition that contains the modacrylic polymer and the compound containing tin and zinc. Specifically, the spinning can be carried out by known methods such as wet spinning, dry spinning, and semi-dry and semi-wet methods. For example, in the case of wet spinning, the modacrylic fiber A can be produced by the general wet spinning for modacrylic fibers, except using a spinning solution containing the modacrylic polymer, the compound containing tin and zinc, and a solvent. Specifically, the modacrylic fiber A can be produced by extruding the spinning solution into a coagulation bath through a nozzle to coagulate it, then subjecting the coagulated filaments to drawing, washing with water, and drying. After drying, as needed, the obtained filaments may be subject to drawing and heat relaxing treatment. Further, the obtained filaments may be crimped and cut into any desired length as needed. The spinning solution may be obtained by dissolving the modacrylic polymer in a solvent and adding the compound containing tin and zinc to the obtained solution of the modacrylic polymer. Alternatively, the spinning solution may be obtained by adding a dispersion of the compound containing tin and zinc which dispersed in a solvent to a solution of the modacrylic polymer which dissolved in a solvent. Examples of the solvent include organic solvents e.g., dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and acetone, and inorganic solvents e.g., a rhodan salt aqueous solution, and a nitric acid aqueous solution.

[0026] In one or more embodiments of the present invention, the flame-retardant fabric contains a magnesium compound, which derived from the modacrylic fiber B. As a result, the flame retardancy, especially the solid-phase flame retardancy of the flame-retardant fabric is improved, and can form a char layer with a thickness of 4.0 mm or more during a flammability test according to ISO 15025. The flame-retardant fabric preferably contains the magnesium compound in an amount of 0.1 mass% or more, more preferably 0.3 mass% or more, and still more preferably 0.5 mass% or more, from the viewpoint of further improving the flame retardancy. The upper limit of the content of the magnesium compound in the flame-retardant fabric is not particularly limited, for example, from the viewpoint of spinnability of the modacrylic fiber B, it is preferably 1.75 mass% or less, more preferably 1.5 mass% or less, and still more preferably 1.375 mass% or less. More specifically, the flame-retardant fabric desirably contains the magnesium compound in an amount of 0.1 to 1.75 mass%, 0.3 to 1.5 mass%, or 0.5 to 1.375 mass%.

[0027] The modacrylic fiber B comprises the magnesium compound, and is substantially free of a compound containing tin and zinc. In this specification, the wording "substantially free of a compound containing tin and zinc" means that a compound containing tin and zinc is not added to a fiber or a fabric on purpose, and accordingly, the state where a compound containing tin and zinc is contained as a contaminant or the like is considered as "substantially free of a compound containing tin and zinc". When the modacrylic fiber B is used together with the modacrylic fiber A, a synergistic effect of the modacrylic fiber A and the modacrylic fiber B is exhibited, making it possible to improve both the gas-phase flame retardancy and the solid-phase flame retardancy.

[0028] A fiber containing a modacrylic polymer and a magnesium compound can be used as the modacrylic fiber B, as long as the flame-retardant fabric can form a char layer with a thickness of 4.0 mm or more during a flammability test according to ISO 15025. The modacrylic fiber B preferably contains the magnesium compound inside the fiber from the viewpoint of flame retardant washing durability.

[0029] The modacrylic fiber B preferably contains the magnesium compound in an amount of 0.6 parts by mass or more, more preferably 0.8 parts by mass or more, still more preferably 1.0 parts by mass or more, and yet more preferably 1.5 parts by mass or more, with respect to 100 parts by mass of the modacrylic polymer, from the viewpoint of further improving the flame retardancy. The modacrylic fiber B preferably contains the magnesium compound in an amount of 6.5 parts by mass or less, more preferably 6.0 parts by mass or less, still more preferably 5.5 parts by mass or less, and yet more preferably 5.0 parts by mass or less, with respect to 100 parts by mass of the modacrylic polymer, from the viewpoint of fiber strength and fabric strength. More specifically, the modacrylic fiber B desirably contains the magnesium compound in an amount of 0.6 to 6.5 parts by mass, 0.8 to 6.0 parts by mass, 1.0 to 5.5 parts by mass, or 1.5 to 5.5 parts by mass, with respect to 100 parts by mass of the modacrylic polymer.

[0030] The modacrylic fiber B preferably contains the magnesium compound in an amount of 0.5 mass% or more, more preferably 0.8 mass% or more, still more preferably 1.2 mass% or more, yet more preferably 1.5 mass% or more, and particular more preferably 1.8 mass% or more, from the viewpoint of the flame retardancy, and especially further improving both the gas-phase flame retardancy and the solid-phase flame retardancy as a result of synergistic effect with the modacrylic fiber A. In addition, the modacrylic fiber B preferably contains the magnesium compound in an amount of 7 mass% or less, more preferably 6 mass% or less, and still more preferably 5.5 mass% or less, from the viewpoint of fiber strength and fabric strength. More specifically, the modacrylic fiber B desirably contains the magnesium compound in an amount of 0.5 to 7 mass%, 0.8 to 6 mass%, 1.2 to 6 mass%, 1.5 to 5.5 mass%, or 1.8 to 5.5 mass%. In this specification, the content of the magnesium compound in a modacrylic fiber may be measured by fluorescence X-ray analysis.

[0031] Examples of the magnesium compound include magnesium oxide, magnesium peroxide, magnesium hydroxide, magnesium fluoride, magnesium chloride, magnesium bromide, magnesium iodide, magnesium hydride, magnesium diboride, magnesium nitride, magnesium sulfide, magnesium carbonate, calcium magnesium carbonate, magnesium nitrate, magnesium sulfate, magnesium sulfite, magnesium perchlorate, trimagnesium phosphate, magnesium permanganate, magnesium phosphate, and the like. Of these compounds, magnesium oxide and magnesium hydroxide may be used preferably from the viewpoint of ease of handling. Furthermore, magnesium hydroxide may be used preferably from the viewpoint of Mohs hardness.

[0032] In one or more embodiments of the present invention, there is no particular limitation on magnesium hydroxide, but examples thereof include powder obtained by pulverizing natural brucite, powder obtained by neutralizing an aqueous solution of a magnesium salt with an alkali, powder obtained by treating magnesium hydroxide particles with a phosphate, a borate, or the like, and a magnesium hydroxide obtained using a method of hydrating magnesium oxide to gradually generate magnesium hydroxide. Furthermore, magnesium hydroxide may have a coating layer that is adsorbed by an adsorbable substance around the particles of magnesium hydroxide, or that is formed through surface treatment with surface treatment agent. In particular, magnesium hydroxide having a coating layer formed through surface treatment with a silane coupling agent is preferable from the viewpoint of suppressing static electricity. The reason why suppression of static electricity is improved through surface treatment with a silane coupling agent is a matter of speculation, but is considered to be as follows. It is conceivable that performing silane coupling treatment on the surface of a magnesium hydroxide particle improves the dispersibility of magnesium hydroxide subjected to the silane coupling treatment and the modacrylic fiber B containing magnesium hydroxide, which results in suppression of static electricity. Furthermore, when a process of attaching oil to the fiber surface is performed for the purpose of improving the processability, an effect of the oil sufficiently reaches the surface of the magnesium hydroxide particle as well, and thus the processability is significantly improved. There is no particular limitation on the type of silane coupling agent as long as the compatibility with a modacrylic polymer, which will be described later, is improved, and both a cross-linked silane coupling agent and a non-cross-linked silane coupling agent can be used.

[0033] A median particle size D50 of the magnesium compound is not particularly limited, for example, from the viewpoint of spinnability, fiber strength, and fabric strength, it is preferably 3.0 µm or less, more preferably 2.5 µm or less, and still more preferably 2.0 µm or less. There is no particular limitation on the lower limit of the median particle size D50 of the magnesium compound, for example, from the viewpoint of the handleability, it may be 0.1 µm or more, 0.5 µm or more, 0.6 µm or more, or 0.7 µm or more. More specifically, the median particle size D50 of the magnesium compound may be 0.1 to 3.0 µm, 0.5 to 2.5 µm, 0.6 to 2.0 µm, or 0.7 to 2.0 µm.

[0034] In the modacrylic fiber B, the modacrylic polymer may be any of those exemplified in the description of the modacrylic fiber A, and a detailed description thereof will be omitted here. Among them, it is preferably the modacrylic polymer contains a halogen-containing vinyl monomer as a halogen-containing monomer, more preferably the modacrylic polymer contains vinyl chloride as a halogen-containing monomer, from the viewpoint of enhancing the synergy effect in the gas-phase flame retardancy with the compound containing tin and zinc contained in the modacrylic fiber A while improving the solid-phase flame retardancy.

[0035] The modacrylic fiber B preferably contains the modacrylic polymer in an amount of 93 to 99.5 mass% and the magnesium compound in an amount of 0.5 to 7 mass%, more preferably contains the modacrylic polymer in an amount of 94 to 98.8 mass% and the magnesium compound in an amount of 1.2 to 6 mass%, and still more preferably contains the modacrylic polymer in an amount of 94.5 to 90.2 mass% and the magnesium compound in an amount of 1.8 to 5.5 mass%, from the viewpoint of the flame retardancy, spinnability, fiber strength, and fabric strength. The modacrylic fiber B may contain one or more other additives e.g., an antistatic agent, a thermal coloration inhibitor, a light resistance improver, a whiteness improver, a devitrification inhibitor, and a colorant, as needed. In the modacrylic fiber B, the other additives may be used in an amount of 10 mass% or less, 5 mass% or less, or 1 mass% or less.

[0036] The modacrylic fiber B may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use.. The single fiber fineness of the modacrylic fiber B, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the modacrylic fiber B is selected as appropriate depending on the intended use and the like of the fabric and work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber (filament fiber) can be used.

[0037] The single fiber strength of the modacrylic fibers B is preferably 1.0 to 4.0 cN / dtex, and more preferably 1.5 to 3.5 cN / dtex, from the viewpoint of durability. Also, the elongation at break of the modacrylic fibers B is preferably 15 to 40%, and more preferably 20 to 30%, from the viewpoint of practicality.

[0038] The modacrylic fiber B can preferably be produced by spinning a composition that contains the modacrylic polymer and the magnesium compound. Specifically, the spinning can be carried out by known methods such as wet spinning, dry spinning, and semi-dry and semi-wet methods. For example, in the case of wet spinning, the modacrylic fiber B can be produced by the general wet spinning for modacrylic fibers, except using a spinning solution containing the modacrylic polymer, the magnesium compound, and a solvent. Specifically, the modacrylic fiber B can be produced by extruding the spinning solution into a coagulation bath through a nozzle to coagulate it, then subjecting the coagulated filaments to drawing, washing with water, and drying. After drying, as needed, the obtained filaments may be subject to drawing and heat relaxing treatment. Further, the obtained filaments may be crimped and cut into any desired length as needed. The spinning solution may be obtained by dissolving the modacrylic polymer in the solvent and adding the magnesium compound to the obtained solution of the modacrylic polymer. Alternatively, the spinning solution may be obtained by adding a dispersion of the magnesium compound which dispersed in a solvent to a solution of the modacrylic polymer which dissolved in a solvent. Examples of the solvent include organic solvents e.g., dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and acetone, and inorganic solvents e.g., a rhodan salt aqueous solution, and a nitric acid aqueous solution.

[0039] The flame-retardant fabric contains the compound containing tin and zinc derived from the modacrylic fiber A and the magnesium compound derived from the modacrylic fiber B, and is substantially free of an antimony compound, thus reducing concerns about environmental impact and also reducing cost. That is, in one or more embodiments of the present invention, each of the modacrylic fiber A, the modacrylic fiber B, and the flame-retardant fabric is substantially free of an antimony compound. In this specification, the wording "substantially free of an antimony compound" means that an antimony compound serving as a flame retardant is not added to a fiber or a fabric on purpose, and accordingly, the state where an antimony compound is contained as a contaminant or the like is considered as "substantially free of an antimony compound".

[0040] As the cellulose fiber, one or more selected from the group consisting of a natural cellulose fiber and a regenerated cellulose fiber can be used.

[0041] Examples of the natural cellulose fiber include a cotton fiber, a kapok fiber, a linen fiber, a hemp fiber, a ramie fiber, a jute fiber, a Manila hemp fiber, and a kenaf fiber.

[0042] Examples of the regenerated cellulose fiber include a rayon fiber, a flame-retardant rayon fiber, a lyocell fiber, and a flame-retardant lyocell fiber. The rayon fiber is obtained by dissolving, in caustic soda, cellulose xanthate produced by the reaction of an alkali and carbon disulfide with a cellulose raw material, followed by wet spinning. The lyocell fiber is obtained by dissolving a cellulose raw material in N-methylmorpholine N-oxide without performing a step of denaturing the cellulose raw material, followed by dry wet spinning.

[0043] The cellulose fiber may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use. The single fiber fineness of the cellulose fiber, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the cellulose fiber is selected as appropriate depending on the intended use and the like of the fabric and work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber that is not cut at all (filament fiber) can be used.

[0044] The flame-retardant fabric preferably contains the modacrylic fiber A in an amount of 25 to 60 mass%, the modacrylic fiber B in an amount of 5 to 25 mass%, and the cellulose fiber in an amount of 30 to 70 mass%, more preferably contains the modacrylic fiber A in an amount of 25 to 50 mass%, the modacrylic fiber B in an amount of 8 to 25 mass%, and the cellulose fiber in an amount of 40 to 70 mass%, and still more preferably contains the modacrylic fiber A in an amount of 25 to 50 mass%, the modacrylic fiber B in an amount of 10 to 25 mass%, and the cellulose fiber in an amount of 40 to 60 mass%. If the content each of the modacrylic fiber A and the modacrylic fiber B is in the above-mentioned range, the synergistic effect the modacrylic fiber A and the modacrylic fiber B is more easily exhibited, and both the gas-phase flame retardancy and the solid-phase flame retardancy are more easily improved. In addition, when the content of cellulose-based fibers is within the above-mentioned range, the texture is good while both the gas-phase and the solid-phase flame retardance are excellent.

[0045] The flame-retardant fabric may contain another fiber in addition to the modacrylic fiber A, the modacrylic fiber B, and the cellulose fiber as long as the effects of the present invention are not inhibited. Examples of the other fiber include a conductive fiber, a heat-resistant fiber, and a high-strength high-elasticity fiber. Examples of the conductive fiber include a metallic fiber, a metal-plated fiber, a copper compound-coated fiber, and a conductive material-containing fiber. Examples of the heat-resistant fiber include a meta-aramid fiber, a polyoxadiazole fiber, a polyimide fiber, and a polyamideimide fiber. Examples of the high-strength high-elasticity fiber include a nylon fiber, a polyester fiber, a para-aramid fiber, and a polyarylate fiber. The flame-retardant fabric may include the other fiber in an amount of 10 mass% or less, 8 mass% or less, 5 mass% or less, or 1 mass% or less.

[0046] The other fiber may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use. The single fiber fineness of the other fiber, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the other fiber is selected as appropriate depending on the intended use and the like of the fabric and work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber (filament fiber) can be used.

[0047] There is no particular limitation on the form of the flame-retardant fabric, and examples thereof include a woven fabric and a knitted fabric. There is no particular limitation on the weave of the woven fabric. Three foundation weaves such as a plain weave, a twill weave, and a sateen weave may be applied, and a patterned woven fabric obtained by using a special loom such as a dobby loom or a Jacquard loom may be used. Also, there is no particular limitation on the knitting of the knitted fabric, and any circular knitting, flat knitting, and warp knitting may be applied. The flame-retardant fabric is preferably a woven fabric, and more preferably a twill woven fabric, from the viewpoint of excellent durability.

[0048] The flame-retardant fabric has excellent flame retardancy, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more, more preferably forms a char layer with a thickness of 4.5 mm or more, and still more preferably forms a char layer with a thickness of 5.0 mm or more after a flammability test according to ISO 15025. Also, an afterflame time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is preferably 3.0 seconds or less, more preferably 2.0 seconds or less, and particular preferably 1.0 seconds or less. Also, an afterglow time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is preferably 2.0 seconds or less, more preferably 1.0 seconds or less, and particular preferably 0 seconds. Thus, the work clothing suitable for use in a flame-retardant work clothing for fire-handling operations such as a protective clothing, a fire-fighting clothing and the like. The flammability test according to ISO 15025 is specifically performed as described in Examples.

[0049] Although there is no particular limitation on the basis weight of the flame-retardant fabric, from the viewpoint of texture, it is preferably 150 to 400 g / m 2< , more preferably 200 to 380 g / m 2< , and still more preferably 220 to 350 g / m 2< .

[0050] The flame-retardant fabric may be used in various textile products (applications). Examples of textile products include the following products.(1) Clothing and Materials of Daily Necessities

[0051] Clothes (including jackets, underwear, sweaters, vests, trousers, and the like), gloves, socks, mufflers, hats, bedding, pillows, cushions, stuffed toys, and the like(2) Special Purpose Clothing

[0052] Work clothing worn by workers who handle fire including protective clothing and firefighting clothing, cold weather clothing, and the like(3) Interior Materials

[0053] Chair upholstery, curtains, wallpaper, carpets, and the like(4) Industrial Materials

[0054] Filters, flame-resistant stuffing, lining materials, and the likeFlame-Retardant Work Clothing

[0055] In one or more embodiments of the present invention, the flame-retardant fabric can be favorably used as a fabric for the work clothing that requires flame retardancy. The flame-retardant work clothing may be produced using the flame-retardant fabric through a known sewing method. The flame-retardant fabric has excellent gas-phase flame retardancy and solid-phase flame retardancy, and thus the flame-retardant work clothing also has excellent gas-phase flame retardancy and solid-phase flame retardancy. The flame-retardant work clothing can be used in any field of work in which the flame retardancy is required. For example, the work clothing can be used as protective clothing (fire-fighting clothing) to be worn by a firefighter, the protective clothing to be worn in workplaces in the fields of petroleum, petrochemistry, coal mining, electric power, welding, and the like in which accidents such as a fire may happen, and the work clothing to be worn in workplaces in the fields of metalwork and the like in which accidents such as a dust explosion are likely to happen, but there is no particular limitation thereto.Examples

[0056] The present invention will be described more specifically with reference to examples. It is to be noted, however, that the present invention is not limited to the following examples.

[0057] The measurement and evaluation methods used in examples and comparative examples are as follows.Median Particle Size D50

[0058] The median particle size D50 of a compound was determined by measuring the particle size distribution of the compound in a dispersion solution of the compound by the laser diffraction method using a laser scattering particle size distribution analyzer (Laser Scattering Particle Size Distribution Analyzer LA-950V2, manufactured by HORIBA, Ltd.).Flame Retardancy

[0059] An afterflame time and an afterglow time of the fabric were evaluated by the flammability test according to procedure A of ISO 15025: 2016. Further, the thickness of the char layer of the fabric after the flammability test was measured and evaluated as follows. In the flammability test based on procedure A of ISO 15025: 2016, a flame (height level:25 ± 2 mm) is ignited for 10 seconds at a distance of 17 ± 1 mm at right angles to an evaluation sample set in the specified holder.<Thickness of Char Layer>

[0060] The thickness of a char layer was measured with a digital thickness gauge ("DTG01", manufactured by Azwan Corporation). When the thickness of the char layer exceeded 1 mm, it was judged as the char layer was foamed, and when the thickness of the char layer was less than 1 mm, it was judged as the char layer was non-foamed.Production Example 1

[0061] A modacrylic polymer containing 51.5 mass% of acrylonitrile, 47.0 mass% of vinylidene chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinylidene chloride, and sodium p-styrenesulfonate was dissolved in dimethyl sulfoxide such that the modacrylic polymer concentration was 30 mass%. A spinning solution was produced by adding, to the obtained solution of the modacrylic polymer, 10 parts by mass of zinc hydroxystannate (manufactured by SCL Italia. Spa, product name "ZHS") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 28 mass% of zinc hydroxystannate to 100 mass% of dimethyl sulfoxide and uniformly dispersing zinc hydroxystannate, and this dispersion liquid was used as a zinc hydroxystannate dispersion liquid. In the zinc hydroxystannate dispersion liquid, the median particle size D50 of zinc hydroxystannate measured through the laser diffraction method was 2.0 µm. The obtained spinning solution was extruded into a 50 mass% aqueous solution of dimethyl sulfoxide through a 300-hole nozzle with a nozzle hole diameter of 0.08 mm and was coagulated, followed by washing the obtained coagulated filaments with water and drying at 120°C. The dried filaments were drawn until the lengths were tripled, followed by heat treatment at 145°C for 5 minutes. Thus, modacrylic fibers were obtained. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.Production Example 2

[0062] A modacrylic polymer containing 49 mass% of acrylonitrile, 49.5 mass% of vinyl chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinyl chloride, and sodium p-styrenesulfonate was dissolved in dimethylformamide such that the concentration of the modacrylic polymer was 30 mass%. A spinning solution was produced by adding, to the obtained modacrylic polymer solution, 5 parts by mass of magnesium hydroxide subjected to silane coupling treatment (manufactured by Kyowa Chemical Industry Co., Ltd., product name "KISMA 5P") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 30 mass% of magnesium hydroxide to 100 mass% of dimethyl sulfoxide and uniformly dispersing magnesium hydroxide, and this dispersion liquid was used as a magnesium hydroxide dispersion liquid. In the magnesium hydroxide dispersion liquid, the median particle size D50 of magnesium hydroxide measured through the laser diffraction method was 2.5 µm. The obtained spinning solution was extruded into a 50 mass% aqueous solution of dimethyl sulfoxide through a 300-hole nozzle with a nozzle hole diameter of 0.08 mm and was coagulated, followed by washing the obtained coagulated filaments with water and drying at 120°C. The dried filaments were drawn until the lengths were tripled, followed by heat treatment at 145°C for 5 minutes. Thus, modacrylic fibers were obtained. The obtained modacrylic fibers had a single fiber fineness of 1.72 dtex, strength of 2.7 cN / dtex, elongation at break of 28%, and a cut length of 38 mm.Production Example 3

[0063] Modacrylic fibers were produced in the same manner as in Production Example 1, except that a spinning solution was produced by adding, to the obtained solution of modacrylic polymer, 8 parts by mass of zinc hydroxystannate and 2 parts by mass of magnesium hydroxide with respect to 100 parts by mass of the modacrylic polymer. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.Production Example 4

[0064] Modacrylic fibers were produced in the same manner as in Production Example 1, except that a spinning solution was produced by adding, to the obtained solution of modacrylic polymer, 10 parts by mass of zinc borate (manufactured by Sakai Chemical Industry Co., Ltd.) with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 28 mass% of zinc borate to 100 mass% of dimethyl sulfoxide and uniformly dispersing zinc borate, and this dispersion liquid was used as a zinc borate dispersion liquid. In the zinc borate dispersion liquid, the median particle size D50 of zinc borate measured through the laser diffraction method was 2.0 µm. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.

[0065] The kinds and the contents of the flame retardant in the modacrylic fibers of Production Examples 1 to 4 are shown in Table 1 below. Table 1Flame retardantKindsContents (mass%)Production Example 1Zinc hydroxystannate9.1Production Example 2Magnesium hydroxide4.8Production Example 3Zinc hydroxystannate7.3Magnesium hydroxide1.8Production Example 4Zinc borate9.1 Examples 1 to 2, and Comparative Examples 1 to 6<Production of Flame-Retardant Fabric>

[0066] The modacrylic fibers and cotton fibers (natural cotton fibers with a cut length of 31 mm or less┘ m) were blended together at ratios shown in Table 2 below, the resulting fiber blend was opened with a carding machine ("sample roller card SC-500", manufactured by DIAWAKIKO Co., LTD.) and produced into slivers using a small drawing machine ("TSM-DFS", manufactured by INTEC Co., LTD.). Then, the obtained slivers were produced into roving yarns by a high-speed roving frame ("FL200", manufactured by TOYOTA INDUSTRIES CORPORATION), and the obtained roving yarns were produced into 20 / 1 count spun yarns by a high-speed spinning frame ("UA37", manufactured by Howa Machinery, Ltd.). A single knitted fabric having a basis weight of about 275 g / m 2< was produced by a computerized flat knitting machine ("SSG 122FC", manufactured by SHIMA SEIKI MFG., LTD.) using the obtained spun yarns.

[0067] The flame retardancy of each of the fabrics obtained in Examples 1 to 2 and Comparative Examples 1 to 6 was measured as described above. Table 3 shows the results. Table 2Blend ratio of fibers (mass%)Production Example 1Production Example 2Production Example 3Production Example 4Cotton FibersEx. 14010--50Ex. 23020--50Comp. Ex. 150---50Comp. Ex. 22030--50Comp. Ex. 3--50-50Comp. Ex. 4---5050Comp. Ex. 5-10-4050Comp. Ex. 6-20-3050 Table 3 Flame retardancyContents of flame retardant in fabric (mass%)Afterflame time (seconds)Afterglow time (seconds)Thickness of char layer (mm)Whether char layer was foamedZinc hydroxystannateMagnesium hydroxideZinc borateEx. 10.905Foamed3.60.50.0Ex. 20.607Foamed2.71.00.0Comp. Ex. 10.901Non-foamed4.50.00.0Comp. Ex. 2Burn downBurn down7Foamed1.81.40.0Comp. Ex. 3Burn downBurn down0.5Non-foamed3.60.90.0Comp. Ex. 40.600.5Non-foamed0.00.04.5Comp. Ex. 5Burn downBurn down0.5Non-foamed0.00.53.6Comp. Ex. 6Burn downBurn down0.5Non-foamed0.01.02.7

[0068] As shown in Table 3 above, in each of the fabrics of the examples, the afterflame time measured by the flammability test according to procedure A of ISO 15025:2016 was 1.0 seconds or less, and the gas-phase flame retardancy was excellent. Also, in each of the fabrics of the examples, the thickness of the char layer after the flammability test according to procedure A of ISO 15025:2016 was 4mm or more, and the solid-phase flame retardancy was excellent.

[0069] On the other hand, in Comparative Example 1, the char layer did not foam due to modacrylic fibers containing a magnesium compound were not used. In the case of Comparative Example 2, where the content of the compound containing tin and zinc in the fabric was low, the fabric burned in the flammability test, exhibiting poor fire extinguishing performance and poor gas-phase flame retardancy. In Comparative Example 3, where modacrylic fibers in which zinc hydroxide stannate and magnesium hydroxide were incorporated in the same fiber together were used, the char layer did not foam and sufficient flame retardancy was not obtained. In Comparative Example 4, where modacrylic fibers containing zinc borate were used, the char layer could not be foamed. In Comparative Examples 5 and 6, in which modacrylic fibers containing zinc borate instead of a compound containing tin and zinc and modacrylic fibers containing a magnesium compound were used in together, the fibers burned in the flammability test, exhibiting poor fire extinguishing performance, also the char layer was not foamed, and both the gas-phase and the solid-phase flame retardancy were poor.

[0070] As can be seen from the data in the examples and comparative examples, when the modacrylic fiber A, which is substantially free of the magnesium compound and contains the compound containing tin and zinc , and the modacrylic fiber B, which is substantially free of the compound containing tin and zinc and contains the magnesium compound, are used together, the synergistic effect the modacrylic fiber A and the modacrylic fiber B is achieved, specifically, both of the gas-phase and the solid-phase flame retardancy are improved.

[0071] The present invention is not particularly limited, and may encompass the following embodiments. [1] A flame-retardant fabric including: a modacrylic fiber A; a modacrylic fiber B; and a cellulose fiber, wherein the modacrylic fiber A includes a compound containing tin and zinc, and is substantially free of a magnesium compound, the modacrylic fiber B comprises a magnesium compound, and is substantially free of a compound containing tin and zinc, the flame-retardant fabric includes the compound containing tin and zinc derived from the modacrylic fiber A in an amount of 2.0 mass% or more, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more after a flammability test according to ISO 15025. [2] The flame-retardant fabric according [1], where the flame-retardant fabric contains the magnesium compound derived from the modacrylic fiber B in an amount of 0.1 mass% or more. [3] The flame-retardant fabric according to [1] or [2], where the compound containing tin and zinc includes a zinc stannate compound. [4] The flame-retardant fabric according to any one of [1] to [3], where the magnesium compound includes magnesium hydroxide. [5] The flame-retardant fabric according to any one of [1] to [4], where the modacrylic fiber A contains the compound containing tin and zinc in an amount of 5 to 20 mass%. [6] The flame-retardant fabric according to any one of [1] to [5], where the modacrylic fiber B contains the magnesium compound in an amount of 0.5 to 7 mass%. [7] The flame-retardant fabric according to any one of [1] to [6], where the modacrylic fiber B contains a modacrylic polymer containing vinyl chloride as a constitutional unit. [8] The flame-retardant fabric according to any one of [1] to [7], where the flame-retardant fabric contains the modacrylic fiber A in an amount of 25 to 60 mass%, the modacrylic fiber B in an amount of 5 to 25 mass%, and the cellulose fiber in an amount of 30 to 70 mass%. [9] The flame-retardant fabric according to any one of [1] to [8], where the cellulose fiber contains a natural cellulose fiber.

[10] The flame-retardant fabric according to any one of [1] to [9], where an afterflame time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is 1.0 seconds or less.

[11] A flame-retardant work clothing including: the flame-retardant fabric according to any one of [1] to

[10] .

Examples

production example 1

[0061]A modacrylic polymer containing 51.5 mass% of acrylonitrile, 47.0 mass% of vinylidene chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinylidene chloride, and sodium p-styrenesulfonate was dissolved in dimethyl sulfoxide such that the modacrylic polymer concentration was 30 mass%. A spinning solution was produced by adding, to the obtained solution of the modacrylic polymer, 10 parts by mass of zinc hydroxystannate (manufactured by SCL Italia. Spa, product name "ZHS") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 28 mass% of zinc hydroxystannate to 100 mass% of dimethyl sulfoxide and uniformly dispersing zinc hydroxystannate, and this dispersion liquid was used as a zinc hydroxystannate dispersion liquid. In the zinc hydroxystannate dispersion liquid, the median particle size D50 of zinc hydroxystannate measured through the laser di...

production example 2

[0062]A modacrylic polymer containing 49 mass% of acrylonitrile, 49.5 mass% of vinyl chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinyl chloride, and sodium p-styrenesulfonate was dissolved in dimethylformamide such that the concentration of the modacrylic polymer was 30 mass%. A spinning solution was produced by adding, to the obtained modacrylic polymer solution, 5 parts by mass of magnesium hydroxide subjected to silane coupling treatment (manufactured by Kyowa Chemical Industry Co., Ltd., product name "KISMA 5P") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 30 mass% of magnesium hydroxide to 100 mass% of dimethyl sulfoxide and uniformly dispersing magnesium hydroxide, and this dispersion liquid was used as a magnesium hydroxide dispersion liquid. In the magnesium hydroxide dispersion liquid, the median particle size D50 of magnesi...

production example 3

[0063]Modacrylic fibers were produced in the same manner as in Production Example 1, except that a spinning solution was produced by adding, to the obtained solution of modacrylic polymer, 8 parts by mass of zinc hydroxystannate and 2 parts by mass of magnesium hydroxide with respect to 100 parts by mass of the modacrylic polymer. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.

Technical Field

[0001] The present invention relates to a flame-retardant fabric including modacrylic fibers and cellulose fibers and a flame-retardant work clothing including the flame-retardant fabric.Background Art

[0002] Halogen-containing fibers e.g., a modacrylic fiber is combined with other fibers e.g., a cellulose fiber, and is generally and especially used suitably in work clothing. On the other hand, halogen-containing fibers e.g., a modacrylic fiber has generally been made flame retardancy by adding about 1 to about 50 parts by mass of a antimony compound as flame retardant (for example, Patent Document 1). However, since the antimony compound may affect the environment and the human body, flame retardants other than the antimony compound are being considered. For example, Patent Document 2 proposes incorporating tin compounds to halogen-containing fibers as compounds that impart flame retardancy, and the halogen-containing fibers used together with cellulose fibers.Citation ListPatent Documents

[0003] Patent Document 1: JP H4(1992)-18050A Patent Document 2: JP H10(1998)-001822A Disclosure of InventionProblems to be Solved by the Invention

[0004] However, when a zinc stannate compound is used as a flame retardant, flame retardancy of the modacrylic fiber is inferior to when an antimony compound is used as a flame retardant.

[0005] To address the above-described conventional problem, the present invention provides a flame-retardant fabric with enhanced flame retardancy while being environmentally friendly, and a flame-retardant work clothing including the flame-retardant fabric.Solution to Problem

[0006] One or more embodiments of the present invention relate to a flame-retardant fabric including: a modacrylic fiber A; a modacrylic fiber B; and a cellulose fiber, where the modacrylic fiber A includes a compound containing tin and zinc, and is substantially free of a magnesium compound, the modacrylic fiber B includes a magnesium compound, and is substantially free of a compound containing tin and zinc, the flame-retardant fabric includes the compound containing tin and zinc derived from the modacrylic fiber A in an amount of 2.0 mass% or more, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more after a flammability test according to ISO 15025.

[0007] One or more embodiments of the present invention relate to a flame-retardant work clothing including the flame-retardant fabric.Effects of the Invention

[0008] The present invention can provide a flame-retardant fabric with enhanced flame retardancy while being environmentally friendly and a flame-retardant work clothing including the flame-retardant fabric.Description of the Invention

[0009] The inventors of the present invention have conducted in-depth studies to improve flame retardancy of a flame-retardant fabric that includes a modacrylic fiber and a cellulose fiber while considering environmentally friendly. As a result, the inventors found that by including a modacrylic fiber A that includes a compound containing tin and zinc, and is substantially free of a magnesium compound, a modacrylic fiber B that includes a magnesium compound, and is substantially free of a compound containing tin and zinc, and a cellulose fiber to the fabric, as well as setting the amount of the compound containing tin and zinc in the fabric within specified range, the fabric can exhibit excellent flame retardancy (gas-phase flame retardancy and solid-phase flame retardancy).

[0010] In particular, surprisingly, the inventors of the present invention have found that when a modacrylic fiber containing a compound containing tin and zinc and a magnesium compound are used in combination with a cellulose fiber, they are less flame retardancy. However, when a cellulose fiber is used in combination with a modacrylic fiber A, that contains a compound containing tin and zinc and is substantially free of magnesium, and a modacrylic fiber B, that contains a magnesium compound and is substantially free of tin and zinc, the synergistic effect of the gas-phase flame retardancy of the compound containing tin and zinc in the modacrylic fiber A and the solid-phase flame retardancy of the magnesium compound in the modacrylic fiber B improves the flame retardancy of the fabric, resulting in extremely high flame retardancy, specifically, the afterflame and afterglow time are shortened, and a foamed char layer is formed, in a flammability test used to evaluate flame retardancy standards for work clothing, such as a flammability test according to ISO 15025. If the thickness of the char layer of the flame-retardant fabric after a flammability test according to ISO 15025 is 4.0 mm or more, a barrier layer is formed by the char layer, which prevents the spread of flames to the back surface, and the work clothing using the flame-retardant fabric have good protection properties for the human body.

[0011] In this specification, when a numerical range is shown using "to", that includes the values at both ends (i.e., the upper limit and the lower limit). For example, a numerical range "A to B" is a range that includes A and B, which are the values at the two ends of the range, and is the same as "A or more and B or less". Also, when a plurality of numerical ranges is described in this specification, numerical ranges obtained by using the upper limits and the lower limits of the different numerical ranges in combination as appropriate are included.Flame-retardant fabric

[0012] In one or more embodiments of the present invention, the flame-retardant fabric contains the compound containing tin and zinc in an amount of 2.0 mass% or more, preferably 2.2 mass% or more, more preferably 2.4 mass% or more, and still more preferably 2.6 mass% or more. The compound containing tin and zinc in the flame-retardant fabric is derived from the modacrylic fiber A, and when the content of the compound containing tin and zinc is within to above mentioned range, the flame retardancy, especially the gas-phase flame retardancy of the flame-retardant fabric is improved. The upper limit of the content of the compound containing tin and zinc in the flame-retardant fabric is not particularly limited, for example, from the viewpoint of spinnability of the modacrylic fiber A, it is preferably 12 mass% or less, more preferably 10 mass% or less, still more preferably 8.0 mass% or less, and yet more preferably 6.0 mass% or less. More specifically, the flame-retardant fabric desirably contains the compound containing tin and zinc in an amount of 2.0 to 12 mass%, 2.2 to 10 mass%, 2.4 to 8.0 mass%, or 2.6 to 6.0 mass%.

[0013] The modacrylic fiber A contains a compound containing tin and zinc, and is substantially free of a magnesium compound. In this specification, the wording "substantially free of a magnesium compound" means that a magnesium compound is not added to a fiber or a fabric on purpose, and accordingly, the state where a magnesium compound is contained as a contaminant or the like is considered as "substantially free of a magnesium compound". When the modacrylic fiber A is used together with the modacrylic fiber B, a synergistic effect is exhibited, making it possible to improve both the gas-phase flame retardancy and the solid-phase flame retardancy.

[0014] The modacrylic fiber A is not particularly limited, and a fiber containing a modacrylic polymer and a compound containing tin and zinc can be used as long as the content of the compound containing tin and zinc in the flame-retardant fabric satisfy the above-mentioned range. The modacrylic fiber A preferably contains the compound containing tin and zinc inside the fiber from the viewpoint of flame retardant washing durability.

[0015] The modacrylic fiber A preferably contains the compound containing tin and zinc in an amount of 5.5 to 25 parts by mass, more preferably 6 to 20 parts by mass, still more preferably 7 to 18 parts by mass, and particular more preferably 8 to 16 parts by mass, with respect to 100 parts by mass of the modacrylic polymer, from the viewpoint of flame retardancy, spinnability, fiber strength, and fabric strength.

[0016] The modacrylic fiber A preferably contains the compound containing tin and zinc in an amount of 5 mass% or more, more preferably 6 mass% or more, still more preferably 7 mass% or more, and particular more preferably 8 mass% or more, from the viewpoint of the flame retardancy, and especially further improving both the gas-phase flame retardancy and the solid-phase flame retardancy as a result of synergistic effect with the modacrylic fiber B. In addition, the modacrylic fiber A preferably contains the compound containing tin and zinc in an amount of 20 mass% or less, more preferably 18 mass% or less, still more preferably 16 mass% or less, and particular more preferably 14 mass% or less, from the viewpoint of fiber strength and fabric strength. More specifically, the modacrylic fiber A desirably contains the compound containing tin and zinc in an amount of 5 to 20 mass%, 6 to 18 mass%, 7 to 16 mass%, or 8 to 14 mass%. In this specification, the content of the compound containing tin and zinc in a modacrylic fiber may be measured by fluorescence X-ray analysis.

[0017] The compound containing tin and zinc is not particularly limited, and from the viewpoint of general purpose, for example, any zinc stannate compound may be used. The zinc stannate compound may be zinc stannate (ZnSnO 3 ) or zinc hydroxystannate (ZnSn(OH) 6 ). Among them, for example, zinc hydroxystannate is preferable, from the viewpoint of further improving flame retardancy of the modacrylic fiber, the fabric, and the work clothing.

[0018] A median particle size D50 of the compound containing tin and zinc is not particularly limited, for example, from the viewpoint of spinnability and fiber strength, it is preferably 3.0 µm or less, more preferably 2.5 µm or less, and still more preferably 2.0 µm or less. There is no particular limitation on the lower limit of the median particle size D50 of the compound containing tin and zinc, for example, from the viewpoint of the handleability, it may be 0.1 µm or more, and from the viewpoint of flame retardancy, it may be 0.5 µm or more, 0.6 µm or more, or 0.7 µm or more. More specifically, the median particle size D50 of the compound containing tin and zinc may be 0.1 to 3.0 µm, 0.5 to 2.5 µm, 0.6 to 2.0 µm, or 0.7 to 2.0 µm. In this specification, the median particle size D50 of a compound may be measured by a laser diffraction / scattering method or a dynamic light scattering method using a dispersion (liquid dispersion) obtained by dispersing the compound in water or an organic solvent.

[0019] A modacrylic polymer containing acrylonitrile, a halogen-containing monomer, and another copolymerizable monomer may be used as the modacrylic polymer. The modacrylic polymer is not particularly limited, and for example, from the viewpoint of further improving the heat resistance and the flame retardancy, the modacrylic polymer preferably contains acrylonitrile in an amount of 30 to 85 mass%, the halogen-containing monomer in an amount of 15 to 70 mass%, and the other copolymerizable monomer in an amount of 0 to 3 mass%, more preferably contains acrylonitrile in an amount of 35 to 75 mass%, the halogen-containing monomer in an amount of 25 to 65 mass%, and the other copolymerizable monomer in an amount of 0 to 3 mass%, and still more preferably contains acrylonitrile in an amount of 40 to 70 mass%, the halogen-containing monomer in an amount of 30 to 60 mass%, and the other copolymerizable monomer in an amount of 0 to 3 mass%.

[0020] Examples of the halogen-containing monomer include a halogen-containing vinyl monomer such as vinyl chloride, vinyl bromide, and the like, and a halogen-containing vinylidene monomer such as vinylidene chloride, vinylidene bromide, and the like. The halogen-containing monomer may be used alone or in combination of two or more. The halogen-containing monomer is preferably the halogen-containing vinylidene monomer from the viewpoint of the heat resistance, and vinylidene chloride is more preferred from the viewpoint of the synergy effect in the flame retardancy with the compound containing tin and zinc.

[0021] The other copolymerizable monomer is not particularly limited as long as they are copolymerizable with acrylonitrile. Examples of the other copolymerizable monomer include unsaturated carboxylic acids typified by acrylic acids and methacrylic acids, as well as salts thereof; esters of unsaturated carboxylic acids, typified by methacrylic esters (e.g. methyl methacrylate), glycidyl methacrylate and the like; vinyl esters typified by vinyl acetate and vinyl butyrate; and sulfonic acid group-containing monomers. Examples of the sulfonic acid group-containing monomers include, but not particularly limited to, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, isoprenesulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid, as well as metal salts, such as sodium salts, and amine salts thereof. The other copolymerizable vinyl monomer may be used alone, or two or more of them may be used in combination. Among them, the sulfonic acid group-containing monomers may be used from the viewpoint of improving dye-affinity.

[0022] The modacrylic fiber A preferably contains the modacrylic polymer in an amount of 80 to 95 mass% and the compound containing tin and zinc in an amount of 5 to 20 mass%, more preferably contains the modacrylic polymer in an amount of 82 to 94 mass% and the compound containing tin and zinc in an amount of 6 to 18 mass%, still more preferably contains the modacrylic polymer in an amount of 83 to 93 mass% and the compound containing tin and zinc in an amount of 7 to 16 mass%, and yet more preferably contains the modacrylic polymer in an amount of 86 to 92 mass% and the compound containing tin and zinc in an amount of 8 to 14 mass%. The modacrylic fiber A may contain one or more other additives e.g., an antistatic agent, a thermal coloration inhibitor, a light resistance improver, a whiteness improver, a devitrification inhibitor, and a colorant, as needed. In the modacrylic fiber A, the other additives may be used in an amount of 10 mass% or less, 5 mass% or less, or 1 mass% or less.

[0023] The modacrylic fiber A may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use.. The single fiber fineness of the modacrylic fiber A, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the modacrylic fiber A is selected as appropriate depending on the intended use and the like of the fabric and the work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber (filament fiber) can be used.

[0024] The single fiber strength of the modacrylic fibers A is preferably 1.0 to 4.0 cN / dtex, and more preferably 1.5 to 3.5 cN / dtex, from the viewpoint of durability. Also, the elongation at break of the modacrylic fibers A is preferably 15 to 40%, and more preferably 20 to 30%, from the viewpoint of practicality. In this specification, the single fiber strength and elongation of a fiber may be measured according to JIS L 1013:2010 or JIS L 1015:2010.

[0025] The modacrylic fiber A can preferably be produced by spinning a composition that contains the modacrylic polymer and the compound containing tin and zinc. Specifically, the spinning can be carried out by known methods such as wet spinning, dry spinning, and semi-dry and semi-wet methods. For example, in the case of wet spinning, the modacrylic fiber A can be produced by the general wet spinning for modacrylic fibers, except using a spinning solution containing the modacrylic polymer, the compound containing tin and zinc, and a solvent. Specifically, the modacrylic fiber A can be produced by extruding the spinning solution into a coagulation bath through a nozzle to coagulate it, then subjecting the coagulated filaments to drawing, washing with water, and drying. After drying, as needed, the obtained filaments may be subject to drawing and heat relaxing treatment. Further, the obtained filaments may be crimped and cut into any desired length as needed. The spinning solution may be obtained by dissolving the modacrylic polymer in a solvent and adding the compound containing tin and zinc to the obtained solution of the modacrylic polymer. Alternatively, the spinning solution may be obtained by adding a dispersion of the compound containing tin and zinc which dispersed in a solvent to a solution of the modacrylic polymer which dissolved in a solvent. Examples of the solvent include organic solvents e.g., dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and acetone, and inorganic solvents e.g., a rhodan salt aqueous solution, and a nitric acid aqueous solution.

[0026] In one or more embodiments of the present invention, the flame-retardant fabric contains a magnesium compound, which derived from the modacrylic fiber B. As a result, the flame retardancy, especially the solid-phase flame retardancy of the flame-retardant fabric is improved, and can form a char layer with a thickness of 4.0 mm or more during a flammability test according to ISO 15025. The flame-retardant fabric preferably contains the magnesium compound in an amount of 0.1 mass% or more, more preferably 0.3 mass% or more, and still more preferably 0.5 mass% or more, from the viewpoint of further improving the flame retardancy. The upper limit of the content of the magnesium compound in the flame-retardant fabric is not particularly limited, for example, from the viewpoint of spinnability of the modacrylic fiber B, it is preferably 1.75 mass% or less, more preferably 1.5 mass% or less, and still more preferably 1.375 mass% or less. More specifically, the flame-retardant fabric desirably contains the magnesium compound in an amount of 0.1 to 1.75 mass%, 0.3 to 1.5 mass%, or 0.5 to 1.375 mass%.

[0027] The modacrylic fiber B comprises the magnesium compound, and is substantially free of a compound containing tin and zinc. In this specification, the wording "substantially free of a compound containing tin and zinc" means that a compound containing tin and zinc is not added to a fiber or a fabric on purpose, and accordingly, the state where a compound containing tin and zinc is contained as a contaminant or the like is considered as "substantially free of a compound containing tin and zinc". When the modacrylic fiber B is used together with the modacrylic fiber A, a synergistic effect of the modacrylic fiber A and the modacrylic fiber B is exhibited, making it possible to improve both the gas-phase flame retardancy and the solid-phase flame retardancy.

[0028] A fiber containing a modacrylic polymer and a magnesium compound can be used as the modacrylic fiber B, as long as the flame-retardant fabric can form a char layer with a thickness of 4.0 mm or more during a flammability test according to ISO 15025. The modacrylic fiber B preferably contains the magnesium compound inside the fiber from the viewpoint of flame retardant washing durability.

[0029] The modacrylic fiber B preferably contains the magnesium compound in an amount of 0.6 parts by mass or more, more preferably 0.8 parts by mass or more, still more preferably 1.0 parts by mass or more, and yet more preferably 1.5 parts by mass or more, with respect to 100 parts by mass of the modacrylic polymer, from the viewpoint of further improving the flame retardancy. The modacrylic fiber B preferably contains the magnesium compound in an amount of 6.5 parts by mass or less, more preferably 6.0 parts by mass or less, still more preferably 5.5 parts by mass or less, and yet more preferably 5.0 parts by mass or less, with respect to 100 parts by mass of the modacrylic polymer, from the viewpoint of fiber strength and fabric strength. More specifically, the modacrylic fiber B desirably contains the magnesium compound in an amount of 0.6 to 6.5 parts by mass, 0.8 to 6.0 parts by mass, 1.0 to 5.5 parts by mass, or 1.5 to 5.5 parts by mass, with respect to 100 parts by mass of the modacrylic polymer.

[0030] The modacrylic fiber B preferably contains the magnesium compound in an amount of 0.5 mass% or more, more preferably 0.8 mass% or more, still more preferably 1.2 mass% or more, yet more preferably 1.5 mass% or more, and particular more preferably 1.8 mass% or more, from the viewpoint of the flame retardancy, and especially further improving both the gas-phase flame retardancy and the solid-phase flame retardancy as a result of synergistic effect with the modacrylic fiber A. In addition, the modacrylic fiber B preferably contains the magnesium compound in an amount of 7 mass% or less, more preferably 6 mass% or less, and still more preferably 5.5 mass% or less, from the viewpoint of fiber strength and fabric strength. More specifically, the modacrylic fiber B desirably contains the magnesium compound in an amount of 0.5 to 7 mass%, 0.8 to 6 mass%, 1.2 to 6 mass%, 1.5 to 5.5 mass%, or 1.8 to 5.5 mass%. In this specification, the content of the magnesium compound in a modacrylic fiber may be measured by fluorescence X-ray analysis.

[0031] Examples of the magnesium compound include magnesium oxide, magnesium peroxide, magnesium hydroxide, magnesium fluoride, magnesium chloride, magnesium bromide, magnesium iodide, magnesium hydride, magnesium diboride, magnesium nitride, magnesium sulfide, magnesium carbonate, calcium magnesium carbonate, magnesium nitrate, magnesium sulfate, magnesium sulfite, magnesium perchlorate, trimagnesium phosphate, magnesium permanganate, magnesium phosphate, and the like. Of these compounds, magnesium oxide and magnesium hydroxide may be used preferably from the viewpoint of ease of handling. Furthermore, magnesium hydroxide may be used preferably from the viewpoint of Mohs hardness.

[0032] In one or more embodiments of the present invention, there is no particular limitation on magnesium hydroxide, but examples thereof include powder obtained by pulverizing natural brucite, powder obtained by neutralizing an aqueous solution of a magnesium salt with an alkali, powder obtained by treating magnesium hydroxide particles with a phosphate, a borate, or the like, and a magnesium hydroxide obtained using a method of hydrating magnesium oxide to gradually generate magnesium hydroxide. Furthermore, magnesium hydroxide may have a coating layer that is adsorbed by an adsorbable substance around the particles of magnesium hydroxide, or that is formed through surface treatment with surface treatment agent. In particular, magnesium hydroxide having a coating layer formed through surface treatment with a silane coupling agent is preferable from the viewpoint of suppressing static electricity. The reason why suppression of static electricity is improved through surface treatment with a silane coupling agent is a matter of speculation, but is considered to be as follows. It is conceivable that performing silane coupling treatment on the surface of a magnesium hydroxide particle improves the dispersibility of magnesium hydroxide subjected to the silane coupling treatment and the modacrylic fiber B containing magnesium hydroxide, which results in suppression of static electricity. Furthermore, when a process of attaching oil to the fiber surface is performed for the purpose of improving the processability, an effect of the oil sufficiently reaches the surface of the magnesium hydroxide particle as well, and thus the processability is significantly improved. There is no particular limitation on the type of silane coupling agent as long as the compatibility with a modacrylic polymer, which will be described later, is improved, and both a cross-linked silane coupling agent and a non-cross-linked silane coupling agent can be used.

[0033] A median particle size D50 of the magnesium compound is not particularly limited, for example, from the viewpoint of spinnability, fiber strength, and fabric strength, it is preferably 3.0 µm or less, more preferably 2.5 µm or less, and still more preferably 2.0 µm or less. There is no particular limitation on the lower limit of the median particle size D50 of the magnesium compound, for example, from the viewpoint of the handleability, it may be 0.1 µm or more, 0.5 µm or more, 0.6 µm or more, or 0.7 µm or more. More specifically, the median particle size D50 of the magnesium compound may be 0.1 to 3.0 µm, 0.5 to 2.5 µm, 0.6 to 2.0 µm, or 0.7 to 2.0 µm.

[0034] In the modacrylic fiber B, the modacrylic polymer may be any of those exemplified in the description of the modacrylic fiber A, and a detailed description thereof will be omitted here. Among them, it is preferably the modacrylic polymer contains a halogen-containing vinyl monomer as a halogen-containing monomer, more preferably the modacrylic polymer contains vinyl chloride as a halogen-containing monomer, from the viewpoint of enhancing the synergy effect in the gas-phase flame retardancy with the compound containing tin and zinc contained in the modacrylic fiber A while improving the solid-phase flame retardancy.

[0035] The modacrylic fiber B preferably contains the modacrylic polymer in an amount of 93 to 99.5 mass% and the magnesium compound in an amount of 0.5 to 7 mass%, more preferably contains the modacrylic polymer in an amount of 94 to 98.8 mass% and the magnesium compound in an amount of 1.2 to 6 mass%, and still more preferably contains the modacrylic polymer in an amount of 94.5 to 90.2 mass% and the magnesium compound in an amount of 1.8 to 5.5 mass%, from the viewpoint of the flame retardancy, spinnability, fiber strength, and fabric strength. The modacrylic fiber B may contain one or more other additives e.g., an antistatic agent, a thermal coloration inhibitor, a light resistance improver, a whiteness improver, a devitrification inhibitor, and a colorant, as needed. In the modacrylic fiber B, the other additives may be used in an amount of 10 mass% or less, 5 mass% or less, or 1 mass% or less.

[0036] The modacrylic fiber B may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use.. The single fiber fineness of the modacrylic fiber B, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the modacrylic fiber B is selected as appropriate depending on the intended use and the like of the fabric and work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber (filament fiber) can be used.

[0037] The single fiber strength of the modacrylic fibers B is preferably 1.0 to 4.0 cN / dtex, and more preferably 1.5 to 3.5 cN / dtex, from the viewpoint of durability. Also, the elongation at break of the modacrylic fibers B is preferably 15 to 40%, and more preferably 20 to 30%, from the viewpoint of practicality.

[0038] The modacrylic fiber B can preferably be produced by spinning a composition that contains the modacrylic polymer and the magnesium compound. Specifically, the spinning can be carried out by known methods such as wet spinning, dry spinning, and semi-dry and semi-wet methods. For example, in the case of wet spinning, the modacrylic fiber B can be produced by the general wet spinning for modacrylic fibers, except using a spinning solution containing the modacrylic polymer, the magnesium compound, and a solvent. Specifically, the modacrylic fiber B can be produced by extruding the spinning solution into a coagulation bath through a nozzle to coagulate it, then subjecting the coagulated filaments to drawing, washing with water, and drying. After drying, as needed, the obtained filaments may be subject to drawing and heat relaxing treatment. Further, the obtained filaments may be crimped and cut into any desired length as needed. The spinning solution may be obtained by dissolving the modacrylic polymer in the solvent and adding the magnesium compound to the obtained solution of the modacrylic polymer. Alternatively, the spinning solution may be obtained by adding a dispersion of the magnesium compound which dispersed in a solvent to a solution of the modacrylic polymer which dissolved in a solvent. Examples of the solvent include organic solvents e.g., dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and acetone, and inorganic solvents e.g., a rhodan salt aqueous solution, and a nitric acid aqueous solution.

[0039] The flame-retardant fabric contains the compound containing tin and zinc derived from the modacrylic fiber A and the magnesium compound derived from the modacrylic fiber B, and is substantially free of an antimony compound, thus reducing concerns about environmental impact and also reducing cost. That is, in one or more embodiments of the present invention, each of the modacrylic fiber A, the modacrylic fiber B, and the flame-retardant fabric is substantially free of an antimony compound. In this specification, the wording "substantially free of an antimony compound" means that an antimony compound serving as a flame retardant is not added to a fiber or a fabric on purpose, and accordingly, the state where an antimony compound is contained as a contaminant or the like is considered as "substantially free of an antimony compound".

[0040] As the cellulose fiber, one or more selected from the group consisting of a natural cellulose fiber and a regenerated cellulose fiber can be used.

[0041] Examples of the natural cellulose fiber include a cotton fiber, a kapok fiber, a linen fiber, a hemp fiber, a ramie fiber, a jute fiber, a Manila hemp fiber, and a kenaf fiber.

[0042] Examples of the regenerated cellulose fiber include a rayon fiber, a flame-retardant rayon fiber, a lyocell fiber, and a flame-retardant lyocell fiber. The rayon fiber is obtained by dissolving, in caustic soda, cellulose xanthate produced by the reaction of an alkali and carbon disulfide with a cellulose raw material, followed by wet spinning. The lyocell fiber is obtained by dissolving a cellulose raw material in N-methylmorpholine N-oxide without performing a step of denaturing the cellulose raw material, followed by dry wet spinning.

[0043] The cellulose fiber may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use. The single fiber fineness of the cellulose fiber, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the cellulose fiber is selected as appropriate depending on the intended use and the like of the fabric and work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber that is not cut at all (filament fiber) can be used.

[0044] The flame-retardant fabric preferably contains the modacrylic fiber A in an amount of 25 to 60 mass%, the modacrylic fiber B in an amount of 5 to 25 mass%, and the cellulose fiber in an amount of 30 to 70 mass%, more preferably contains the modacrylic fiber A in an amount of 25 to 50 mass%, the modacrylic fiber B in an amount of 8 to 25 mass%, and the cellulose fiber in an amount of 40 to 70 mass%, and still more preferably contains the modacrylic fiber A in an amount of 25 to 50 mass%, the modacrylic fiber B in an amount of 10 to 25 mass%, and the cellulose fiber in an amount of 40 to 60 mass%. If the content each of the modacrylic fiber A and the modacrylic fiber B is in the above-mentioned range, the synergistic effect the modacrylic fiber A and the modacrylic fiber B is more easily exhibited, and both the gas-phase flame retardancy and the solid-phase flame retardancy are more easily improved. In addition, when the content of cellulose-based fibers is within the above-mentioned range, the texture is good while both the gas-phase and the solid-phase flame retardance are excellent.

[0045] The flame-retardant fabric may contain another fiber in addition to the modacrylic fiber A, the modacrylic fiber B, and the cellulose fiber as long as the effects of the present invention are not inhibited. Examples of the other fiber include a conductive fiber, a heat-resistant fiber, and a high-strength high-elasticity fiber. Examples of the conductive fiber include a metallic fiber, a metal-plated fiber, a copper compound-coated fiber, and a conductive material-containing fiber. Examples of the heat-resistant fiber include a meta-aramid fiber, a polyoxadiazole fiber, a polyimide fiber, and a polyamideimide fiber. Examples of the high-strength high-elasticity fiber include a nylon fiber, a polyester fiber, a para-aramid fiber, and a polyarylate fiber. The flame-retardant fabric may include the other fiber in an amount of 10 mass% or less, 8 mass% or less, 5 mass% or less, or 1 mass% or less.

[0046] The other fiber may be either a short fiber or a long fiber, and can be selected as appropriate depending on the method of use. The single fiber fineness of the other fiber, which is selected as appropriate depending on the intended use and the like of the fabric and work clothing, is preferably 1 to 50 dtex, more preferably 1.5 to 30 dtex, and still more preferably 1.7 to 15 dtex. The fiber length of the other fiber is selected as appropriate depending on the intended use and the like of the fabric and work clothing. For example, a short cut fiber (fiber length: 0.1 to 5 mm), a short fiber (fiber length: 15 to 176 mm, 20 to 160 mm, 25 to 138 mm, or 30 to 128 mm), or a long fiber (filament fiber) can be used.

[0047] There is no particular limitation on the form of the flame-retardant fabric, and examples thereof include a woven fabric and a knitted fabric. There is no particular limitation on the weave of the woven fabric. Three foundation weaves such as a plain weave, a twill weave, and a sateen weave may be applied, and a patterned woven fabric obtained by using a special loom such as a dobby loom or a Jacquard loom may be used. Also, there is no particular limitation on the knitting of the knitted fabric, and any circular knitting, flat knitting, and warp knitting may be applied. The flame-retardant fabric is preferably a woven fabric, and more preferably a twill woven fabric, from the viewpoint of excellent durability.

[0048] The flame-retardant fabric has excellent flame retardancy, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more, more preferably forms a char layer with a thickness of 4.5 mm or more, and still more preferably forms a char layer with a thickness of 5.0 mm or more after a flammability test according to ISO 15025. Also, an afterflame time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is preferably 3.0 seconds or less, more preferably 2.0 seconds or less, and particular preferably 1.0 seconds or less. Also, an afterglow time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is preferably 2.0 seconds or less, more preferably 1.0 seconds or less, and particular preferably 0 seconds. Thus, the work clothing suitable for use in a flame-retardant work clothing for fire-handling operations such as a protective clothing, a fire-fighting clothing and the like. The flammability test according to ISO 15025 is specifically performed as described in Examples.

[0049] Although there is no particular limitation on the basis weight of the flame-retardant fabric, from the viewpoint of texture, it is preferably 150 to 400 g / m 2< , more preferably 200 to 380 g / m 2< , and still more preferably 220 to 350 g / m 2< .

[0050] The flame-retardant fabric may be used in various textile products (applications). Examples of textile products include the following products.(1) Clothing and Materials of Daily Necessities

[0051] Clothes (including jackets, underwear, sweaters, vests, trousers, and the like), gloves, socks, mufflers, hats, bedding, pillows, cushions, stuffed toys, and the like(2) Special Purpose Clothing

[0052] Work clothing worn by workers who handle fire including protective clothing and firefighting clothing, cold weather clothing, and the like(3) Interior Materials

[0053] Chair upholstery, curtains, wallpaper, carpets, and the like(4) Industrial Materials

[0054] Filters, flame-resistant stuffing, lining materials, and the likeFlame-Retardant Work Clothing

[0055] In one or more embodiments of the present invention, the flame-retardant fabric can be favorably used as a fabric for the work clothing that requires flame retardancy. The flame-retardant work clothing may be produced using the flame-retardant fabric through a known sewing method. The flame-retardant fabric has excellent gas-phase flame retardancy and solid-phase flame retardancy, and thus the flame-retardant work clothing also has excellent gas-phase flame retardancy and solid-phase flame retardancy. The flame-retardant work clothing can be used in any field of work in which the flame retardancy is required. For example, the work clothing can be used as protective clothing (fire-fighting clothing) to be worn by a firefighter, the protective clothing to be worn in workplaces in the fields of petroleum, petrochemistry, coal mining, electric power, welding, and the like in which accidents such as a fire may happen, and the work clothing to be worn in workplaces in the fields of metalwork and the like in which accidents such as a dust explosion are likely to happen, but there is no particular limitation thereto.Examples

[0056] The present invention will be described more specifically with reference to examples. It is to be noted, however, that the present invention is not limited to the following examples.

[0057] The measurement and evaluation methods used in examples and comparative examples are as follows.Median Particle Size D50

[0058] The median particle size D50 of a compound was determined by measuring the particle size distribution of the compound in a dispersion solution of the compound by the laser diffraction method using a laser scattering particle size distribution analyzer (Laser Scattering Particle Size Distribution Analyzer LA-950V2, manufactured by HORIBA, Ltd.).Flame Retardancy

[0059] An afterflame time and an afterglow time of the fabric were evaluated by the flammability test according to procedure A of ISO 15025: 2016. Further, the thickness of the char layer of the fabric after the flammability test was measured and evaluated as follows. In the flammability test based on procedure A of ISO 15025: 2016, a flame (height level:25 ± 2 mm) is ignited for 10 seconds at a distance of 17 ± 1 mm at right angles to an evaluation sample set in the specified holder.<Thickness of Char Layer>

[0060] The thickness of a char layer was measured with a digital thickness gauge ("DTG01", manufactured by Azwan Corporation). When the thickness of the char layer exceeded 1 mm, it was judged as the char layer was foamed, and when the thickness of the char layer was less than 1 mm, it was judged as the char layer was non-foamed.Production Example 1

[0061] A modacrylic polymer containing 51.5 mass% of acrylonitrile, 47.0 mass% of vinylidene chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinylidene chloride, and sodium p-styrenesulfonate was dissolved in dimethyl sulfoxide such that the modacrylic polymer concentration was 30 mass%. A spinning solution was produced by adding, to the obtained solution of the modacrylic polymer, 10 parts by mass of zinc hydroxystannate (manufactured by SCL Italia. Spa, product name "ZHS") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 28 mass% of zinc hydroxystannate to 100 mass% of dimethyl sulfoxide and uniformly dispersing zinc hydroxystannate, and this dispersion liquid was used as a zinc hydroxystannate dispersion liquid. In the zinc hydroxystannate dispersion liquid, the median particle size D50 of zinc hydroxystannate measured through the laser diffraction method was 2.0 µm. The obtained spinning solution was extruded into a 50 mass% aqueous solution of dimethyl sulfoxide through a 300-hole nozzle with a nozzle hole diameter of 0.08 mm and was coagulated, followed by washing the obtained coagulated filaments with water and drying at 120°C. The dried filaments were drawn until the lengths were tripled, followed by heat treatment at 145°C for 5 minutes. Thus, modacrylic fibers were obtained. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.Production Example 2

[0062] A modacrylic polymer containing 49 mass% of acrylonitrile, 49.5 mass% of vinyl chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinyl chloride, and sodium p-styrenesulfonate was dissolved in dimethylformamide such that the concentration of the modacrylic polymer was 30 mass%. A spinning solution was produced by adding, to the obtained modacrylic polymer solution, 5 parts by mass of magnesium hydroxide subjected to silane coupling treatment (manufactured by Kyowa Chemical Industry Co., Ltd., product name "KISMA 5P") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 30 mass% of magnesium hydroxide to 100 mass% of dimethyl sulfoxide and uniformly dispersing magnesium hydroxide, and this dispersion liquid was used as a magnesium hydroxide dispersion liquid. In the magnesium hydroxide dispersion liquid, the median particle size D50 of magnesium hydroxide measured through the laser diffraction method was 2.5 µm. The obtained spinning solution was extruded into a 50 mass% aqueous solution of dimethyl sulfoxide through a 300-hole nozzle with a nozzle hole diameter of 0.08 mm and was coagulated, followed by washing the obtained coagulated filaments with water and drying at 120°C. The dried filaments were drawn until the lengths were tripled, followed by heat treatment at 145°C for 5 minutes. Thus, modacrylic fibers were obtained. The obtained modacrylic fibers had a single fiber fineness of 1.72 dtex, strength of 2.7 cN / dtex, elongation at break of 28%, and a cut length of 38 mm.Production Example 3

[0063] Modacrylic fibers were produced in the same manner as in Production Example 1, except that a spinning solution was produced by adding, to the obtained solution of modacrylic polymer, 8 parts by mass of zinc hydroxystannate and 2 parts by mass of magnesium hydroxide with respect to 100 parts by mass of the modacrylic polymer. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.Production Example 4

[0064] Modacrylic fibers were produced in the same manner as in Production Example 1, except that a spinning solution was produced by adding, to the obtained solution of modacrylic polymer, 10 parts by mass of zinc borate (manufactured by Sakai Chemical Industry Co., Ltd.) with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 28 mass% of zinc borate to 100 mass% of dimethyl sulfoxide and uniformly dispersing zinc borate, and this dispersion liquid was used as a zinc borate dispersion liquid. In the zinc borate dispersion liquid, the median particle size D50 of zinc borate measured through the laser diffraction method was 2.0 µm. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.

[0065] The kinds and the contents of the flame retardant in the modacrylic fibers of Production Examples 1 to 4 are shown in Table 1 below. Table 1Flame retardantKindsContents (mass%)Production Example 1Zinc hydroxystannate9.1Production Example 2Magnesium hydroxide4.8Production Example 3Zinc hydroxystannate7.3Magnesium hydroxide1.8Production Example 4Zinc borate9.1 Examples 1 to 2, and Comparative Examples 1 to 6<Production of Flame-Retardant Fabric>

[0066] The modacrylic fibers and cotton fibers (natural cotton fibers with a cut length of 31 mm or less┘ m) were blended together at ratios shown in Table 2 below, the resulting fiber blend was opened with a carding machine ("sample roller card SC-500", manufactured by DIAWAKIKO Co., LTD.) and produced into slivers using a small drawing machine ("TSM-DFS", manufactured by INTEC Co., LTD.). Then, the obtained slivers were produced into roving yarns by a high-speed roving frame ("FL200", manufactured by TOYOTA INDUSTRIES CORPORATION), and the obtained roving yarns were produced into 20 / 1 count spun yarns by a high-speed spinning frame ("UA37", manufactured by Howa Machinery, Ltd.). A single knitted fabric having a basis weight of about 275 g / m 2< was produced by a computerized flat knitting machine ("SSG 122FC", manufactured by SHIMA SEIKI MFG., LTD.) using the obtained spun yarns.

[0067] The flame retardancy of each of the fabrics obtained in Examples 1 to 2 and Comparative Examples 1 to 6 was measured as described above. Table 3 shows the results. Table 2Blend ratio of fibers (mass%)Production Example 1Production Example 2Production Example 3Production Example 4Cotton FibersEx. 14010--50Ex. 23020--50Comp. Ex. 150---50Comp. Ex. 22030--50Comp. Ex. 3--50-50Comp. Ex. 4---5050Comp. Ex. 5-10-4050Comp. Ex. 6-20-3050 Table 3 Flame retardancyContents of flame retardant in fabric (mass%)Afterflame time (seconds)Afterglow time (seconds)Thickness of char layer (mm)Whether char layer was foamedZinc hydroxystannateMagnesium hydroxideZinc borateEx. 10.905Foamed3.60.50.0Ex. 20.607Foamed2.71.00.0Comp. Ex. 10.901Non-foamed4.50.00.0Comp. Ex. 2Burn downBurn down7Foamed1.81.40.0Comp. Ex. 3Burn downBurn down0.5Non-foamed3.60.90.0Comp. Ex. 40.600.5Non-foamed0.00.04.5Comp. Ex. 5Burn downBurn down0.5Non-foamed0.00.53.6Comp. Ex. 6Burn downBurn down0.5Non-foamed0.01.02.7

[0068] As shown in Table 3 above, in each of the fabrics of the examples, the afterflame time measured by the flammability test according to procedure A of ISO 15025:2016 was 1.0 seconds or less, and the gas-phase flame retardancy was excellent. Also, in each of the fabrics of the examples, the thickness of the char layer after the flammability test according to procedure A of ISO 15025:2016 was 4mm or more, and the solid-phase flame retardancy was excellent.

[0069] On the other hand, in Comparative Example 1, the char layer did not foam due to modacrylic fibers containing a magnesium compound were not used. In the case of Comparative Example 2, where the content of the compound containing tin and zinc in the fabric was low, the fabric burned in the flammability test, exhibiting poor fire extinguishing performance and poor gas-phase flame retardancy. In Comparative Example 3, where modacrylic fibers in which zinc hydroxide stannate and magnesium hydroxide were incorporated in the same fiber together were used, the char layer did not foam and sufficient flame retardancy was not obtained. In Comparative Example 4, where modacrylic fibers containing zinc borate were used, the char layer could not be foamed. In Comparative Examples 5 and 6, in which modacrylic fibers containing zinc borate instead of a compound containing tin and zinc and modacrylic fibers containing a magnesium compound were used in together, the fibers burned in the flammability test, exhibiting poor fire extinguishing performance, also the char layer was not foamed, and both the gas-phase and the solid-phase flame retardancy were poor.

[0070] As can be seen from the data in the examples and comparative examples, when the modacrylic fiber A, which is substantially free of the magnesium compound and contains the compound containing tin and zinc , and the modacrylic fiber B, which is substantially free of the compound containing tin and zinc and contains the magnesium compound, are used together, the synergistic effect the modacrylic fiber A and the modacrylic fiber B is achieved, specifically, both of the gas-phase and the solid-phase flame retardancy are improved.

[0071] The present invention is not particularly limited, and may encompass the following embodiments. [1] A flame-retardant fabric including: a modacrylic fiber A; a modacrylic fiber B; and a cellulose fiber, wherein the modacrylic fiber A includes a compound containing tin and zinc, and is substantially free of a magnesium compound, the modacrylic fiber B comprises a magnesium compound, and is substantially free of a compound containing tin and zinc, the flame-retardant fabric includes the compound containing tin and zinc derived from the modacrylic fiber A in an amount of 2.0 mass% or more, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more after a flammability test according to ISO 15025. [2] The flame-retardant fabric according [1], where the flame-retardant fabric contains the magnesium compound derived from the modacrylic fiber B in an amount of 0.1 mass% or more. [3] The flame-retardant fabric according to [1] or [2], where the compound containing tin and zinc includes a zinc stannate compound. [4] The flame-retardant fabric according to any one of [1] to [3], where the magnesium compound includes magnesium hydroxide. [5] The flame-retardant fabric according to any one of [1] to [4], where the modacrylic fiber A contains the compound containing tin and zinc in an amount of 5 to 20 mass%. [6] The flame-retardant fabric according to any one of [1] to [5], where the modacrylic fiber B contains the magnesium compound in an amount of 0.5 to 7 mass%. [7] The flame-retardant fabric according to any one of [1] to [6], where the modacrylic fiber B contains a modacrylic polymer containing vinyl chloride as a constitutional unit. [8] The flame-retardant fabric according to any one of [1] to [7], where the flame-retardant fabric contains the modacrylic fiber A in an amount of 25 to 60 mass%, the modacrylic fiber B in an amount of 5 to 25 mass%, and the cellulose fiber in an amount of 30 to 70 mass%. [9] The flame-retardant fabric according to any one of [1] to [8], where the cellulose fiber contains a natural cellulose fiber.

[10] The flame-retardant fabric according to any one of [1] to [9], where an afterflame time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is 1.0 seconds or less.

[11] A flame-retardant work clothing including: the flame-retardant fabric according to any one of [1] to

[10] .

Examples

production example 1

[0061]A modacrylic polymer containing 51.5 mass% of acrylonitrile, 47.0 mass% of vinylidene chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinylidene chloride, and sodium p-styrenesulfonate was dissolved in dimethyl sulfoxide such that the modacrylic polymer concentration was 30 mass%. A spinning solution was produced by adding, to the obtained solution of the modacrylic polymer, 10 parts by mass of zinc hydroxystannate (manufactured by SCL Italia. Spa, product name "ZHS") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 28 mass% of zinc hydroxystannate to 100 mass% of dimethyl sulfoxide and uniformly dispersing zinc hydroxystannate, and this dispersion liquid was used as a zinc hydroxystannate dispersion liquid. In the zinc hydroxystannate dispersion liquid, the median particle size D50 of zinc hydroxystannate measured through the laser di...

production example 2

[0062]A modacrylic polymer containing 49 mass% of acrylonitrile, 49.5 mass% of vinyl chloride, and 1.5 mass% of sodium p-styrenesulfonate which was obtained through emulsion polymerization of the acrylonitrile, vinyl chloride, and sodium p-styrenesulfonate was dissolved in dimethylformamide such that the concentration of the modacrylic polymer was 30 mass%. A spinning solution was produced by adding, to the obtained modacrylic polymer solution, 5 parts by mass of magnesium hydroxide subjected to silane coupling treatment (manufactured by Kyowa Chemical Industry Co., Ltd., product name "KISMA 5P") with respect to 100 parts by mass of the modacrylic polymer. A dispersion liquid was prepared in advance by adding 30 mass% of magnesium hydroxide to 100 mass% of dimethyl sulfoxide and uniformly dispersing magnesium hydroxide, and this dispersion liquid was used as a magnesium hydroxide dispersion liquid. In the magnesium hydroxide dispersion liquid, the median particle size D50 of magnesi...

production example 3

[0063]Modacrylic fibers were produced in the same manner as in Production Example 1, except that a spinning solution was produced by adding, to the obtained solution of modacrylic polymer, 8 parts by mass of zinc hydroxystannate and 2 parts by mass of magnesium hydroxide with respect to 100 parts by mass of the modacrylic polymer. The obtained modacrylic fibers had a single fiber fineness of 1.7 dtex, strength of 2.4 cN / dtex, elongation at break of 29%, and a cut length of 38 mm.

Claims

1. A flame-retardant fabric comprising: a modacrylic fiber A; a modacrylic fiber B; and a cellulose fiber, wherein the modacrylic fiber A comprises a compound containing tin and zinc, and is substantially free of a magnesium compound, the modacrylic fiber B comprises a magnesium compound, and is substantially free of a compound containing tin and zinc, the flame-retardant fabric comprises the compound containing tin and zinc derived from the modacrylic fiber A in an amount of 2.0 mass% or more, and the flame-retardant fabric forms a char layer with a thickness of 4.0 mm or more after a flammability test according to ISO 15025.

2. The flame-retardant fabric according to claim 1, wherein the flame-retardant fabric comprises the magnesium compound derived from the modacrylic fiber B in an amount of 0.1 mass% or more.

3. The flame-retardant fabric according to claim 1, wherein the compound containing tin and zinc comprises a zinc stannate compound.

4. The flame-retardant fabric according to claim 1, wherein the magnesium compound comprises magnesium hydroxide.

5. The flame-retardant fabric according to claim 1, wherein the modacrylic fiber A comprises the compound containing tin and zinc in an amount of 5 to 20 mass%.

6. The flame-retardant fabric according to claim 1, wherein the modacrylic fiber B comprises the magnesium compound in an amount of 0.5 to 7 mass%.

7. The flame-retardant fabric according to claim 1, wherein the modacrylic fiber B comprises a modacrylic polymer containing vinyl chloride.

8. The flame-retardant fabric according to claim 1, wherein the flame-retardant fabric comprises the modacrylic fiber A in an amount of 25 to 60 mass%, the modacrylic fiber B in an amount of 5 to 25 mass%, and the cellulose fiber in an amount of 30 to 70 mass%.

9. The flame-retardant fabric according to claim 1, wherein the cellulose fiber comprises a natural cellulose fiber.

10. The flame-retardant fabric according to claim 1, wherein an afterflame time of the flame-retardant fabric measured by a flammability test according to ISO 15025 is 1.0 seconds or less.

11. A flame-retardant work clothing comprising: the flame-retardant fabric according to any one of claims 1 to 10.

Images