US20120015185A1 - Flameproof rayon fiber, method for manufacturing the same and flameproof fiber structure - Google Patents

Flameproof rayon fiber, method for manufacturing the same and flameproof fiber structure Download PDF

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Publication number
US20120015185A1
US20120015185A1 US13/258,979 US200913258979A US2012015185A1 US 20120015185 A1 US20120015185 A1 US 20120015185A1 US 200913258979 A US200913258979 A US 200913258979A US 2012015185 A1 US2012015185 A1 US 2012015185A1
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Prior art keywords
fiber
sodium
flameproof
rayon fiber
mass
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US13/258,979
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Shigeo Fushitani
Makoto Hayashi
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Daiwabo Rayon Co Ltd
Daiwabo Holdings Co Ltd
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Daiwabo Rayon Co Ltd
Daiwabo Holdings Co Ltd
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Assigned to DAIWABO HOLDINGS CO., LTD., DAIWABO RAYON CO., LTD. reassignment DAIWABO HOLDINGS CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FUSHITANI, SHIGEO, HAYASHI, MAKOTO
Publication of US20120015185A1 publication Critical patent/US20120015185A1/en
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
    • D01F2/06—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from viscose
    • D01F2/08—Composition of the spinning solution or the bath
    • D01F2/10—Addition to the spinning solution or spinning bath of substances which exert their effect equally well in either
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber

Definitions

  • the present invention relates to a flameproof rayon fiber, a method for manufacturing the flameproof rayon fiber, and a flameproof fiber structure.
  • Patent document 1 proposes production of a composite fiber by mixing viscose and sodium silicate and spinning the mixture in a bath containing sulfuric acid.
  • Patent document 2 proposes a cellulose fiber including aluminum, which is obtained by mixing sodium silicate with viscose and using sodium aluminate in the scouring process.
  • Patent document 3 proposes a cellulose fiber including Mg, which is obtained by mixing sodium silicate with viscose and bring the fiber into contact with an alkali solution containing Mg in the scouring or aftertreatment process.
  • the cellulose fiber disclosed in Patent document 1 merely is a complex of cellulose and silicic acid.
  • a glass skeleton is formed but decomposition of cellulose cannot be inhibited. Therefore, it is necessary to further improve the flame retardance.
  • the cellulose fiber disclosed in Patent document 2 contains aluminum, it has been suggested that aluminum could be neurotoxic. Thus, a further improvement in safety is necessary.
  • the cellulose fiber disclosed in Patent document 3 is exposed to high temperatures, a glass skeleton is formed, so that not only the fiber exhibits a flameproof ability but also it has washing durability.
  • efforts to perform Mg treatment may become complicated.
  • the present invention provides a flameproof rayon fiber having excellent flameproofness as well as excellent flame retardance, a method for manufacturing the flameproof rayon fiber and a flameproof fiber structure.
  • the flameproof rayon fiber according to the present invention is a rayon fiber that includes components of silicon and sodium. Glass remains in the rayon fiber when the rayon fiber is burned at 800° C., the glass has the property of softening at 800° C., and when subjected to an X-ray fluorescence analysis, the rayon fiber has a silicon content in the range of 5 to 30% by mass and a sodium content in a range of 0.1 to 3% by mass.
  • the method for manufacturing the flameproof rayon fiber according to the present invention includes preparing an undiluted viscose solution; adding a solution containing a silicic compound containing an alkali metal to the undiluted viscose solution so as to make an alkali metal-containing silicic compound-added viscose solution; performing spinning by extruding the silicic compound-added viscose solution through a spinneret into a spinbath containing a sulfuric acid, thus producing a fiber to be treated containing the silicic compound; and treating, in a scouring or aftertreatment process, the fiber to be treated with a solution having a pH in the range of 4 to 11 and a buffer action and containing sodium.
  • the flameproof fiber structure of the present invention contains at least 30% by mass of the flameproof rayon fiber.
  • the flameproof rayon fiber according to the present invention exhibits excellent flameproof ability and self extinguishability (flame retardance) because the rayon fiber contains components of silicon and sodium. Further, the flameproof rayon fiber according to the present invention is not halogenic. Thus, even if the fiber is burned, gas that emerges due to the burning does not contain toxic substances such as cyan and halogen compounds. Moreover, since the principal component of the flameproof rayon fiber according to the present invention is rayon, the fiber is degradable in soil.
  • FIG. 1 is a micrograph showing a flameproof rayon fiber of one example of the present invention being ashed at 800° C.
  • FIG. 2 is a micrograph showing a flameproof rayon fiber of another example of the present invention being ashed at 800° C.
  • FIG. 3 is a micrograph showing a flameproof rayon fiber of a comparative example being ashed at 800° C.
  • FIG. 4 is a micrograph showing a flameproof rayon fiber of another comparative example being ashed at 800° C.
  • flameproofness refers to a flame barrier property that can be achieved as a result of a glass skeleton being remaining. More specifically, even when in contact with a flame, an afterflame time is short and a damaged area is small. Such an ability is useful for providing a property in which, for example, even when a cigarette smoked in bed falls onto a sheet, the sheet only becomes charred and the fire does not spread.
  • flame retardance refers to a property of having self-extinguishability and a fiber itself is resistant to burning. More specifically, it is such a property that even when fire is set to an opened fiber staple, the fire self extinguishes without causing a flash.
  • the flameproof rayon fiber according to the present invention contains components of silicon and sodium.
  • the rayon fiber according to the present invention softens at temperatures lower than 1000° C., for example, at a temperature of about 800° C. as the temperature of a burning cigarette, and has biodegradability. Since components other than the rayon component form compounds containing silicon and sodium (mainly, sodium silicate), the rayon fiber has a reduced load to the environment.
  • the rayon fiber is a fiber obtained by xanthating cellulose, followed by dilution and dissolution in dilute alkali so as to prepare viscose, and then coagulating and regenerating this viscose.
  • the rayon fiber is not limited particularly by its material such as cellulose or manufacturing method.
  • the flameproof rayon fiber contains silicon and sodium, it is assumed that the flameproof rayon fiber forms a soda glass structure when it is burned and its softening point drops. Consequently, the glass softens quickly in high temperatures such as about 800° C., inhibiting decomposition of cellulose. Normally, when cellulose is burned, the burning continues because gas resulting from the decomposition due to the heat is combustible. However, because the flameproof rayon fiber forms a soda glass structure when it is burned, decomposition of cellulose is inhibited to suppress the burning and the fire self extinguishes.
  • the flameproof rayon fiber When subjected to an X-ray fluorescence analysis, the flameproof rayon fiber has a silicon content of 5 to 30% by mass, preferably in the range of 8 to 23% by mass, and more preferably in the range of 13 to 19% by mass.
  • the flameproof rayon fiber When subjected to an X-ray fluorescence analysis, the flameproof rayon fiber has a sodium content of 0.1 to 3% by mass, preferably in the range of 0.15 to 1.5% by mass, and more preferably in the range of 0.2 to 1.0% by mass.
  • the sodium content in the flameproof rayon fiber according to the present invention to the mentioned range, it is possible to achieve a flameproof rayon fiber having more favorable flameproofness and self-extinguishability.
  • the ratio of the silicon content to the sodium content (mass ratio of silicon/sodium) in the flameproof rayon fiber is preferably 10 or more and less than 90.
  • the mass ratio of silicon/sodium is a parameter that indicates the susceptibility of the fiber to softening. The smaller the mass ratio of silicon/sodium, the likelier it is for the flameproof rayon fiber to soften when being burned due to the formation of soda glass within the fiber, and thus, the self-extinguishability (flame retardance) improves.
  • the mass ratio of silicon/sodium is more preferably 15 to 70.
  • the mass ratio of silicon/sodium is less than 90, the chance of sodium silicate (xNa 2 .ySiO 2 .zH 2 O; where x is 1 to 5, y ⁇ x, and z is 1 to 3) being formed is relatively high, so that favorable flame retardance can be achieved. Further, when the mass ratio of silicon/sodium is 10 or more, the flameproof rayon fiber softens while leaving a glass skeleton, so that favorable flameproofness and flame retardance can be achieved.
  • Sodium may be present in the flameproof rayon fiber such that at least part thereof is contained in the rayon fiber and the remaining part is adhered to the surface of the rayon fiber. Whether sodium is present in the rayon fiber (inside the fiber) or not can be determined by washing the fiber with water.
  • the silicon and the sodium compound are not limited particularly by which state they are in. They may be mixed uniformly in the fiber or may be present in a compatible or incompatible state. As long as the sodium is partially present in the form of a sodium compound such as sodium silicate, the remaining may be contained in the form of sodium salt such as sodium oxide and sodium hydroxide.
  • the flameproof rayon fiber has an ash content preferably in the range of 10 to 50% by mass, more preferably in the range of 15 to 40% by mass, and particularly preferably in the range of 25 to 38% by mass.
  • the ash content refers to an inorganic material left as a remainder after an organic material is incinerated at high temperatures.
  • the ash content is less than 10% by mass, the flameproofness of the flameproof rayon fiber tends to drop.
  • the ash content exceeds 50% by mass, the strength of the flameproof rayon fiber tends to drop or the texture thereof tends to be impaired.
  • the ash content exceeds 40% by mass, it tends to be difficult to achieve the same texture as conventional rayon fibers that do not use a flame retardant.
  • the ash content of the flameproof rayon fiber according to the present invention is measured in conformity with JIS L 1015 8.20 and is a value expressed by percent by mass of the mass of a component remaining after burning a flameproof rayon fiber at 850° C. with respect to an absolute dry mass of the flameproof rayon fiber. The same holds true for the following.
  • the flameproof rayon fiber has an LOI value of preferably 31 or more, and more preferably 32 or more by twisted fiber string measurement (E-1) in conformity with JIS L 1091 E (oxygen index test). Further, the flameproof rayon fiber has an LOI value of preferably 23 or more, and more preferably 24 or more by nonwoven fabric measurement (E-2) in conformity with JIS L 1091 E (oxygen index test).
  • the LOI values of the rayon fiber according to the present invention satisfy the mentioned ranges, respectively.
  • the flameproof rayon fiber is preferable because it has flame retardance as well as flameproofness.
  • the flameproof rayon fiber has an L value (whiteness) of preferably 40 to 90, more preferably 44 to 86, and particularly preferably 48 to 70.
  • the L value is a whiteness indicator with a scale of 0 (black) to 100 (white). As the value is larger and positive, the color becomes whiter. Although the L value of 100 means that the color is white, the whiteness of typical rayon fibers is about 92 to 95. Due to a change in the hue of cellulose at the time of heating, the color does not become pure white. Therefore, it tends to be difficult to produce rayon fibers having an L value of more than 90. As for rayon fibers having an L value of less than 40, their hue tends to deteriorate when they are processed in the form of product, so that the product value tends to drop.
  • the flameproof rayon fiber is not particularly limited by its fineness and generally has a fineness in the range of 1 to 17 dtex, and preferably in the range of 1.7 to 10 dtex. When the fineness is less than 1 dtex, the strength of the rayon fiber tends to drop. When the fineness exceeds 17 dtex, the thickness of the fiber becomes excessively large, so that the fiber tends to be coarse. Also, the flameproof rayon fiber is not particularly limited by its length, either, and can be used as a filament or a staple.
  • the fiber length can be set freely, and the fiber with a length of 5 to 20 mm can be used as a paper screen, a wallpaper or the like and that with a length of 20 to 200 mm can be used for a nonwoven fabric or a spun yarn.
  • a filament tow can be used without cutting after the scouring.
  • the cross-section of the flameproof rayon fiber is not particularly limited by its shape but can be selected suitably according to the intended use.
  • a circular shape, a deformed circular shape, a hollow shape, an oblate shape, etc. can be selected.
  • the flameproof rayon fiber according to the present invention has useful physical properties that rayon as regenerated cellulose generally has, such as biodegradability, water absorptivity, hygroscopicity, antistatic property and thermal stability. Since rayon as the principal component of the flameproof rayon fiber according to the present invention has biodegradability, it can be decomposed within one to three months when buried in the soil. Further, the components other than rayon are compounds principally containing silicic acid and sodium (mainly, sodium silicate). Therefore, the flameproof rayon fiber according to the present invention has a reduced load to the environment.
  • the flameproof rayon fiber according to the present invention can be obtained as follows. First, a silicic compound containing an alkali metal, for example, sodium silicate (Na 2 O.nSiO 2 .xH 2 O; where n is 1 to 3 and x is 10 to 20) is added to an undiluted viscose solution to prepare an alkali metal-containing silicic compound-added viscose solution (hereinafter, simply referred to as the viscose solution). Then, spinning is carried out by extruding the viscose solution through a spinneret into a spinbath containing a sulfuric acid (H 2 SO 4 ) to produce a fiber to be treated containing the silicic compound.
  • an alkali metal for example, sodium silicate (Na 2 O.nSiO 2 .xH 2 O; where n is 1 to 3 and x is 10 to 20)
  • an undiluted viscose solution hereinafter, simply referred to as the viscose solution.
  • the silicic compound containing an alkali metal for example, sodium silicate (Na 2 O.nSiO 2 .xH 2 O; where n is 1 to 3 and x is 10 to 20) in the viscose solution reacts with the sulfuric acid (H 2 SO 4 ) and turns into silicon dioxide (SiO 2 ; in the form of polymer).
  • the obtained fiber is treated with a solution having a pH in the range of 4 to 11 and a buffer action and containing sodium, thus obtaining the flameproof rayon fiber according to the present invention.
  • silicon and sodium react with each other and form a compound.
  • the compound containing silicon and sodium has the following structure in the rayon fiber.
  • silicic acid forms a layered structure and sodium in the form of sodium oxide is present between the layers of the unit structure.
  • the silicic acid and the sodium oxide are bonded to each other due to sharing some part of oxygen, so that a gel of silicic acid and sodium is produced to form sodium silicate (xNa 2 O.ySiO 2 .zH 2 O; where x is 1 to 5, y ⁇ x, and z is 1 to 3).
  • conventional flameproof rayon fiber manufacturing is carried out in the same manner as the manufacturing method according to the present invention until the step where sodium silicate reacts with sulfuric acid and turns into silicon dioxide.
  • the spinbath can be a general acid spinbath containing sulfuric acid, for example, a Muller bath containing H 2 SO 4 , ZnSO 4 and Na 2 SO 4 in the ranges of 110 to 170 g/liter, 10 to 30 g/liter and 150 to 350 g/liter, respectively. Further, the temperature of the spinbath generally is 45 to 65° C.
  • the undiluted viscose solution may have a general composition.
  • the silicic compound containing an alkali metal preferably is in the range of 10 to 100% by mass and more preferably in the range of 25 to 70% by mass on the basis of silicon dioxide (SiO 2 ) with respect to the mass of cellulose contained in the undiluted viscose solution. Since the silicic compound containing an alkali metal in the viscose solution is considered to react with the sulfuric acid (H 2 SO 4 ) and turn into silicon dioxide (SiO 2 ; in the form of polymer), the values are expressed on the basis of silicon dioxide (SiO 2 ).
  • the silicon dioxide contained in the mentioned range makes it possible to maintain the strength and texture of the fiber, so that, when treated with the sodium-containing solution, a rayon fiber having favorable flameproofness can be manufactured.
  • the silicate compound containing an alkali metal can be, for example, sodium silicate.
  • the process of adding the silicate compound containing an alkali metal such as sodium silicate may be carried out by mixing an aqueous solution of the silicate compound containing an alkali metal in a general undiluted viscose solution.
  • the ratio of the sodium silicate to be added is preferably in the range of 10 to 100% by mass, more preferably in the range of 15 to 80% by mass and particularly preferably in the range of 30 to 70% by mass on the basis of SiO 2 with respect to cellulose in the undiluted viscose solution.
  • the amount of sodium silicate is preferably in the range of 10 to 100% by mass, more preferably in the range of 15 to 80% by mass and particularly preferably in the range of 30 to 70% by mass on the basis of SiO 2 with respect to cellulose in the undiluted viscose solution.
  • the fiber to be treated containing a silicon component that has been obtained in the spinning process is treated with the solution having a pH in the range of 4 to 11 and a buffer action and containing sodium, thereby allowing the silicon and the sodium to react with each other, so that a compound containing silicon and sodium is formed.
  • the compound containing silicon and sodium is estimated to form sodium silicate.
  • a treatment of bringing the fiber to be treated into contact with the sodium-containing solution having a buffer action in place of sulfuric acid after bleaching during the scouring process a treatment of bringing the fiber to be treated into contact with the sodium-containing solution having a buffer action after souring during the scouring process; a treatment of mixing an oil solution component with the sodium-containing solution having a buffer action and brining the fiber to be treated into contact with the mixed solution in an oil solution treatment in the scouring process; and a treatment of steeping the fiber to be treated in the sodium-containing solution having a buffer action (as an aftertreatment process) after scouring and drying the fiber to be treated.
  • the bath ratio may be selected suitably in accordance with the sodium-containing solution having a buffer action to be used, and the mass of the fiber to be treated the mass of the solution is in the range of 1:10 to 1:1000, for example. Further, it is generally possible to carry out favorable treatment when the bath temperature is in the range of 0 to 100° C. and the steeping time is about 30 sec, and preferably in the range of 20 to 300 sec.
  • the sodium-containing solution having a buffer action may have a pH in the range of 4 to 11, preferably in the range of 6 to 10, more preferably in the range of 7 to 8.6, and particularly preferably in the range of 7.3 to 8.6.
  • a pH in the range of 4 to 11, preferably in the range of 6 to 10, more preferably in the range of 7 to 8.6, and particularly preferably in the range of 7.3 to 8.6.
  • the pH is less than 4, sodium does not penetrate the fiber, so that self extinguishability cannot be achieved.
  • the pH exceeds 11 the silicic acid content in the fiber leaches out, resulting in a low ash content after the treatment. Consequently, it becomes difficult to achieve the flameproofness.
  • the sodium-containing solution having a buffer action is preferably an aqueous solution having a pH in the range of 4 to 11.
  • the “sodium-containing solution having a buffer action” refers to a solution having a buffer action, in other words, a buffer solution containing sodium and having a pH in the range of 4 to 11 and the solution may in any form.
  • a buffer solution containing water-soluble sodium salt having no buffer action and sodium salt having a buffer action it is possible to use a buffer solution containing water-soluble sodium salt having no buffer action and sodium salt having a buffer action, a buffer solution containing sodium salt having a buffer action, and a buffer solution containing water-soluble sodium salt having no buffer action and an agent having a buffer action such as weak acid or weak base.
  • a buffer solution containing sodium salt having a buffer action is preferable in terms of taking sodium into the fiber in an efficient manner.
  • the water-soluble sodium salt having no buffer action sodium chloride, sodium sulfate, sodium nitrate or the like can be used.
  • sodium salts having a buffer action include sodium hydrogen carbonate (baking soda), sodium carbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium citrate.
  • a buffer solution of alkalescent sodium carbonate or sodium hydrogen carbonate is more preferable in terms of applications where inclusion of phosphorus components is undesirable or in terms of pH.
  • the sodium salt content of the sodium-containing solution having a buffer action is preferably defined by the concentration of sodium ions in terms of controlling the solution.
  • the concentration of sodium ions in the sodium-containing solution having a buffer action is preferably in the range of 500 to 10,000 mg/L, and more preferably in the range of 1,000 to 8,000 mg/L.
  • a flameproof fiber structure such as woven fabric, knit fabric and nonwoven fabric can be obtained.
  • the content of the flameproof rayon fiber in the flameproof fiber structure is preferably 30% by mass, and more preferably 60 to 80% by mass. When the content of the flameproof rayon fiber is 30% by mass or more, it is possible to obtain a flameproof fiber structure having excellent flameproofness and flame retardance.
  • Other fibers used in the flameproof fiber structure are not particularly limited, and examples of the other fibers include binder fibers such as low-melting polyester fibers, flame retardant acrylic (modacrylic) fibers such as “Kanekaron” (trade name, manufactured by Kaneka Corporation) and nonflammable fibers such as aramid (aromatic polyimide) fibers.
  • binder fibers such as low-melting polyester fibers
  • flame retardant acrylic (modacrylic) fibers such as “Kanekaron” (trade name, manufactured by Kaneka Corporation)
  • nonflammable fibers such as aramid (aromatic polyimide) fibers.
  • the flameproof rayon fiber according to the present invention is a rayon fiber having favorable flameproofness and flame retardance. Further, the rayon fiber has excellent texture, resistance to dry-cleaning and biodegradability.
  • the flameproof rayon fiber according to the present invention is processed into woven fabric, knit fabric, nonwoven fabric, etc. and useful for the purposes such as disaster prevention items, kitchen fan filters, sheets, pillow cases, bedding mats, bedding covers, fire protection screens, interior goods (carpets, chair coverings, curtains, wall paper bases, wall materials, etc.), vehicle interior materials (mats, lining fabric, etc.), etc., for example.
  • the sodium silicate-added viscose solution was spun at a spinning speed of 50 m/min and at a stretch ratio of 50% by two bath stretch spinning, thus obtaining fibers having a fineness of about 3.3 dtex.
  • the composition of a first bath (spinbath) was such that a sulfuric acid accounted for 115 g/liter, zinc sulfate accounted for 15 g/liter and sodium sulfate accounted for 350 g/liter, and the temperature of the first bath was 48° C. and the temperature of a second bath (hot water bath) was set to 85° C.
  • the sodium silicate-added viscose solution was extruded through a spinneret, thus producing a silicon-containing rayon filament tow (fibers to be treated).
  • the filament tow cut into a fiber length of 51 mm with a cutter was used in the scouring process.
  • the scouring process included a hot water treatment, bleaching, souring and water-washing in this order. Excess moisture was removed by compression rollers, followed by drying for seven hours in a constant-temperature dryer at 60° C.
  • the resultant fibers to be treated had physical properties such as a fineness of 3.3 dtex, a dry strength of 1.4 cN/dtex, a wet strength of 0.8 cN/dtex, a dry elongation of 25% and a wet elongation of 20%.
  • a sodium-containing solution having a buffer action As a sodium-containing solution having a buffer action (hereinafter referred to as a sodium-based buffer solution), an aqueous solution (bath temperature: 50° C., pH: 7.76) containing 0.38% by mass of sodium sulfate and 0.05% by mass of sodium hydrogen carbonate was used.
  • the dried fibers to be treated were steeped for 30 sec. At this time, the bath ratio was set such that the mass of the fibers to be treated:the mass of the aqueous solution was 1:20.
  • the fibers to be treated were washed with water and then dewatered centrifugally. Finally, the fibers were dried in a constant-temperature dryer at 105° C. for 30 minutes, thus obtaining flameproof rayon fibers b of Example 1 (in the following, referred to as the fibers b).
  • Flameproof rayon fibers c (hereinafter referred to as the fibers c) of Example 2 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 7.79) containing 0.34% by mass of sodium sulfate and 0.1% by mass of sodium hydrogen carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 7.79
  • Flameproof rayon fibers d (hereinafter referred to as the fibers d) of Example 3 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 7.93) containing 0.17% by mass of sodium sulfate and 0.3% by mass of sodium hydrogen carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 7.93
  • Flameproof rayon fibers e (hereinafter referred to as the fibers e) of Example 4 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 7.31) containing 0.41% by mass of sodium sulfate and 0.01% by mass of sodium hydrogen carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers f (hereinafter referred to as the fibers f) of Example 5 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.40) containing 0.1% by mass of sodium hydrogen carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 8.40
  • a sodium-based buffer solution 0.1% by mass of sodium hydrogen carbonate
  • Flameproof rayon fibers g (hereinafter referred to as the fibers g) of Example 6 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.42) containing 0.5% by mass of sodium hydrogen carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 8.42
  • a sodium-based buffer solution 0.5% by mass of sodium hydrogen carbonate
  • Flameproof rayon fibers h (hereinafter referred to as the fibers h) of Example 7 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.43) containing 1.0% by mass of sodium hydrogen carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers i (hereinafter referred to as the fibers i) of Example 8 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 4.69) containing 0.5% by mass of sodium dihydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 4.69 containing 0.5% by mass of sodium dihydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers j (hereinafter referred to as the fibers j) of Example 9 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 4.53) containing 1.0% by mass of sodium dihydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers k (hereinafter referred to as the fibers k) of Example 10 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 4.24) containing 3.0% by mass of sodium dihydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers 1 (hereinafter referred to as the fibers 1 ) of Example 11 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 10.86) containing 0.5% by mass of sodium carbonate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 10.86
  • Flameproof rayon fibers m (hereinafter referred to as the fibers m) of Example 12 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.70) containing 0.5% by mass of disodium hydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 8.70
  • disodium hydrogen phosphate 0.5% by mass of disodium hydrogen phosphate
  • Flameproof rayon fibers n (hereinafter referred to as the fibers n) of Example 13 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.76) containing 1.0% by mass of disodium hydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 8.76
  • Flameproof rayon fibers o (hereinafter referred to as the fibers o) of Example 14 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.79) containing 3.0% by mass of disodium hydrogen phosphate was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers p (hereinafter referred to as the fibers p) of Example 15 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.3) containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 94.7:5.3 was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers q (hereinafter referred to as the fibers q) of Example 16 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 8.0) containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 91.5:8.5 was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 8.0
  • 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 91.5:8.5 was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers r (hereinafter referred to as the fibers r) of Example 17 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 7.6) containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 81:19 was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers s (hereinafter referred to as the fibers s) of Example 18 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 7.2) containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 61:39 was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 7.2
  • aqueous solution bath temperature: 50° C., pH: 7.2
  • Flameproof rayon fibers t (hereinafter referred to as the fibers t) of Example 19 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 6.8) containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 37.5:62.5 was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 6.8 containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 37.5:62.5 was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers u (hereinafter referred to as the fibers u) of Example 20 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 6.3) containing 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 18.5:81.5 was used as a sodium-based buffer solution in the aftertreatment.
  • an aqueous solution bath temperature: 50° C., pH: 6.3
  • 0.2M of disodium hydrogen phosphate and 0.2M of sodium dihydrogen phosphate at a ratio (volume ratio) of 18.5:81.5 was used as a sodium-based buffer solution in the aftertreatment.
  • Flameproof rayon fibers a (hereinafter referred to as the fibers a) of Comparative Example 1 were manufactured in the same manner as Example 1 except that the fibers to be treated were not subjected to aftertreatment with an aqueous solution containing sodium.
  • Flameproof rayon fibers v (hereinafter referred to as the fibers v) of Comparative Example 3 were manufactured in the same manner as Example 1 except that an aqueous solution (bath temperature: 50° C., pH: 7.8) containing 3% by mass of sodium sulfate was used in the aftertreatment.
  • the ash content was measured in conformity with JIS L 1015 8.20. Specifically, the mass of a component remaining after burning each of the fibers having a mass of 1 g for two hours in an electric furnace at 850° C. was measured so as to determine the ash content of each of the fibers. Incidentally, the ash content is a percent by mass of the mass of the residual component after burning with respect to the mass obtained by subtracting a water content from the mass of the fibers. Further, after the fibers were washed with water, their ash contents were determined in the same manner. The water-washing was carried out as follows.
  • a water absorption test method (weaved basket method) as one of the purity test methods for absorbent cotton defined by the Japanese Pharmacopoeia was applied. Specifically, 2 g of fibers were scaled and they were put into a container. As the container, a cylindrical basket processed with an enameled wire and having a height of 8 cm and a diameter of about 5 cm ⁇ was used. After putting the fibers into the container uniformly, the container was steeped in ion-exchanged water at 25° C. for three minutes. Subsequently, the fibers were taken out from the container and dewatered centrifugally, followed by drying in a drier. The dried fibers were used as a water-washed sample.
  • each evaluation sample was produced by opening 1 to 2 g of cut fibers into a web using a carding machine and rendering this web in the form of fiber mass. Further, the fibers were water-washed in the manner described above, subjected to a flame in the same manner and observed. On the basis of the observation results, the flame retardance was evaluated on a scale from A to D as follows.
  • A when a flame was brought close to a fiber mass, only the part to which the flame was applied burned and the remaining part did not burn.
  • B when a flame was brought close to a fiber mass, fire traveled somewhat on the surface of the fiber mass but went out when the flame was moved away.
  • C when a flame was brought close to a fiber mass, fire traveled on the surface of the fiber mass and the fire remained even when the flame was moved away.
  • D when the flame was brought close to a fiber mass, fire spread.
  • the whiteness (L value) was measured in conformity with JIS L 1015 8.17 C (by Hunter) as follows. 20 g of fibers opened with a carding machine were placed in a constant-temperature ventilation drier (trade name: “FC-612”, manufactured by Advantec Toyo Kaisha, Ltd.) set at a temperature of 190° C. for heat treatment for five minutes, thus producing a sample. A whiteness meter “ZE-2000” manufactured by Nippon Denshoku Industries Co., LTD. was used to measure the whiteness. 20 g of the produced sample was put into a container included with the whiteness meter and the orientation of the sample was changed to measure the color four times (L, a, b). The average of the values (L values) obtained from the four measurements was adopted as the fiber whiteness.
  • test piece In conformity with JIS L 1091 E (oxygen index test) and with the use of an oxygen index flammability tester (ON-1 type) manufactured by Toyo Rika Kogyo Co., LTD, a twisted fiber string (E-1) or nonwoven fabric (E-2) as a test piece was attached to a holder to measure the LOI value.
  • the test piece was produced as follows.
  • E-1 test piece (twisted fiber string): 1 g of a sample staple was opened and adjusted to have a fiber length of 20 to 30 cm. Then, the fibers were fixed on one end and twists were applied to the fibers from the other end. Specifically, twists were applied to the fibers while pulling the fibers, and the application of twists was stopped immediately before the emergence of bumps. Subsequently, the twisted fibers were folded into two parts at the center, thus producing a twisted fiber string having a length of about 110 mm and a width of about 6 mm.
  • E-2 test piece (nonwoven fabric): 30% by mass of low-melting polyester fibers (trade name: “4080”, manufactured by Unitika LTD., fineness: 4.4 dtex, fiber length: 51 mm) and 70% by mass of the flameproof rayon fibers were mixed with each other, the mixture was rendered in the form of card webs using a carding machine, and the card web was placed on another such that the total mass per unit area reached 300 g/m 2 . Subsequently, the card web were placed on a punching plate, a nylon mesh was placed on top of the card webs, and a weight was placed on top of the nylon mesh such that a load of 20 g/cm 2 was applied thereto.
  • a constant-temperature ventilation drier (trade name: “FC-612”, manufactured by Advantec Toyo Kaisha, Ltd.) set at a temperature of 180° C. After being set aside for 10 minutes in the drier, they were taken out and thus obtaining a nonwoven fabric having a length of 150 mm and a width of 60 mm.
  • the fibers were set aside in an electric furnace set to a default temperature of 800° C. and ashing of the fibers was observed with a microscope (trade name: “ECLIPSE E600”, manufactured by Nikon Corporation, magnification: 320 ⁇ ) to check the presence or absence of softening and the presence or absence of bubbles.
  • the flameproof rayon fibers of Examples had an LOI value of 31 or more when measured in the form of a twisted fiber string (E-1 method) and an LOI value of 24 or more when measured in the form of a nonwoven fabric (E-2 method). Thus, they had excellent flame retardance.
  • FIGS. 1 to 4 are micrographs respectively showing the flameproof rayon fibers of Examples 2 and 5 and Comparative Examples 1 and 2 being ashed at 800° C.
  • the fibers of Comparative Examples were not softened at 800° C. and no bubbles were observed.
  • the fibers of Examples softened and bubbles were observed. That is, the fibers of Examples formed a soda glass structure when being burned, so that their softening point dropped. Thus, the glass softened quickly in high temperatures and inhibited the decomposition of cellulose.
  • the fibers e tended to have somewhat low flame retardance because the component having a buffer action of the aqueous solution used in the aftertreatment was in small amount.
  • the fibers f tended to have somewhat low flame retardance because the concentration of sodium ions in the aqueous solution used in the aftertreatment was small.
  • the fibers i, j and k tended to have somewhat low flame retardance because the aqueous solutions used in the aftertreatment all had a low pH.
  • the fiber v (Comparative Example) did not have flame retardance because the aqueous solution used in the aftertreatment contained sodium but did not contain an agent having a buffer action, in other words, the aqueous solution was not a buffer solution containing sodium. It is considered that this was due to the absence of sodium in the fibers.
  • the whiteness of their samples after heat treatment at 190° C. was measured.
  • the fibers i, j and k had high whiteness, in other words, they maintained whiteness but tended to have somewhat low flame retardance.
  • the fibers l had low whiteness, in other words, they were tinted but had high flame retardance.
  • the fibers l were at a level that might result in reduction in product value depending on the applications.
  • the remaining fibers of Examples all maintained high flame retardance and product value.
  • the components of the fibers a and HEWN (Comparative Example) and the fibers b, f and g and the water-washed fibers g were determined by an X-ray fluorescence analysis as follows. Table 3 provides the results.
  • the X-ray fluorescence analysis was performed using an X-ray fluorescence spectrometer “LAB CENTER XRF-1700,” manufactured by Shimadzu Corporation, by a theoretical calculation by an FP method.
  • the outline of this measurement device and the measurement conditions are as follows.
  • Range of elements to be measured 4 Be to 92 U
  • X-ray tube 4 kw thin window, Rh target
  • Primary X-ray filter four-kind automatic exchange (Al, Ti, Ni, Zr)
  • cut fibers of the fibers a and HELON (Comparative Examples) and the fibers b, f, g and the water-washed fibers g were used.
  • the measurement was made such that the irradiation surface was adjusted to be 10 mm ⁇ in diameter and several millimeters in thickness and irradiated with light reaching from above and passing therethrough.
  • the fibers b, f and g and the waterwashed fibers g contained components of silicon and sodium and the components formed sodium silicate.
  • the fibers g were waterwashed to check the resistance of the flame retardance to waterwashing.
  • the fibers maintained a sodium content of 0.1% by mass or more even after being washed with water. Further, as can be seen from the results of the fibers g after waterwashing, at least sodium was partially present in the fibers.
  • the card webs were placed on a punching plate, a nylon mesh was placed on top of the card webs, and a weight was placed on top of the nylon mesh such that a load of 20 g/cm 2 was applied thereto. Then, they were placed in a constant-temperature ventilation drier (trade name: “FC-612”, manufactured by Advantec Toyo Kaisha, Ltd.) set at a temperature of 180° C. They were set aside in the drier for 10 minutes to let the low-molten polyester fibers melt to bond the fibers to each other. The nonwoven fabric was taken out from the drier, and thus obtaining the flameproof nonwoven fabric.
  • the flameproof nonwoven fabrics respectively containing the fibers b, g, l and m of Examples exhibited favorable flame retardance.
  • the present invention can provide a flameproof rayon fiber having favorable flameproofness for preventing fire as well as flame retardance (self-extinguishability), and a method for manufacturing the flameproof rayon fiber.
  • the rayon fiber which is the principal component of the present invention, has biodegradability, while other components mainly are compounds containing silicon and sodium, so that a flameproof rayon fiber with a reduced load to the environment can be provided.
  • the flameproof rayon fiber according to the present invention can be used as a material replacing glass fibers, asbestos, aramid fibers, etc., which have been used conventionally in flameproof products.
  • the flameproof rayon fiber according to the present invention is processed into woven fabric, knit fabric, nonwoven fabric, etc.

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  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Artificial Filaments (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)
US13/258,979 2009-12-28 2009-12-28 Flameproof rayon fiber, method for manufacturing the same and flameproof fiber structure Abandoned US20120015185A1 (en)

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US2373881A (en) * 1940-04-27 1945-04-17 Mathieson Alkali Works Inc Rayon bleaching and scouring treatment
US20080093767A1 (en) * 2004-06-02 2008-04-24 Sateri International Co. Ltd. Method for Manufacturing Silicate-Containing Fiber
US20080214081A1 (en) * 2004-03-27 2008-09-04 Mewa Textil-Service Ag & Co. Management Ohg Fabric
US20090030131A1 (en) * 2005-08-26 2009-01-29 Daiwabo Co., Ltd. Flameproof Rayon Fiber and Method for Manufacturing the Same

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NL293694A (ja) 1962-07-30
US3565749A (en) * 1967-02-27 1971-02-23 Fmc Corp High temperature resistant structures
JPH03179104A (ja) * 1989-12-06 1991-08-05 Mitsubishi Heavy Ind Ltd 蒸気タービン車室
JPH0494052A (ja) * 1990-08-09 1992-03-26 Matsushita Electron Corp メタルハライドランプ
FI91778C (fi) 1991-12-31 1994-08-10 Kemira Fibres Oy Piidioksidia sisältävä tuote ja menetelmä sen valmistamiseksi
CN1037458C (zh) * 1994-02-03 1998-02-18 赵玉山 纤维素聚硅酸盐阻燃纤维及其生产方法
CN101037812A (zh) * 2007-04-06 2007-09-19 山东海龙股份有限公司 抗融阻燃粘胶纤维及其制备方法

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US2373881A (en) * 1940-04-27 1945-04-17 Mathieson Alkali Works Inc Rayon bleaching and scouring treatment
US20080214081A1 (en) * 2004-03-27 2008-09-04 Mewa Textil-Service Ag & Co. Management Ohg Fabric
US20080093767A1 (en) * 2004-06-02 2008-04-24 Sateri International Co. Ltd. Method for Manufacturing Silicate-Containing Fiber
US20090030131A1 (en) * 2005-08-26 2009-01-29 Daiwabo Co., Ltd. Flameproof Rayon Fiber and Method for Manufacturing the Same

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