JPH083813A - Production of flame-retardant acrylonitrile synthetic fiber - Google Patents

Abstract

PURPOSE:To enable simple production of flame-retardant acrylonitrile (AN) fiber by melt-extruding an AN copolymer containing vinyl chloride and/or vinylidene chloride as an essential comonomer using water as a plasticizer without requirig an organic solvent. CONSTITUTION:An AN copolymer containing vinyl chloride and/or vinylidene chloride as essential comonomers is melt-extruded into fibers using water as a plasticizer. When more than 0.4wt.% of a flame retarder is added to a molten mixture of the AN copolymer with water, the flame retardancy of the fiber is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flame-retardant acrylonitrile synthetic fiber by a melt spinning method.

[0002]

2. Description of the Related Art When making acrylic synthetic fibers flame-retardant,
A method by copolymerization with a flame retardant component such as vinyl chloride and / or vinylidene chloride and / or a halogenated phosphate ester,
There is a method by adding a flame retardant such as zinc oxide, and it is well known that flame-retardant acrylic synthetic fibers that are far superior in flame retardancy can be obtained by maintaining the texture of acrylic fibers. .

In JP-A-53-28728, an acrylonitrile copolymer consisting of 20 to 80% by weight of acrylonitrile and 80 to 20% by weight of vinyl chloride or vinylidene chloride and finely divided zinc oxalate, zinc phosphate or boron. Acetone using acrylonitrile-based synthetic fiber, which has good dyeability and is flame-retardant, consisting of zinc acid salt, as a solvent,
A method for producing by a dry or wet spinning method using acetonitrile, dimethylformamide or dimethylacetamide is disclosed.

Further, in JP-A-48-44526, at least 6000 centipoise (25 ° C.) obtained by mixing a halogenated phosphoric acid ester with a solid halogen- and / or phosphorus-containing organic compound and dissolving it in a known solvent. Disclosed is a method for producing a flame-retardant acrylonitrile-based synthetic fiber obtained by introducing a fluid mixture having viscosity into an acrylonitrile-based synthetic fiber structure.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The methods disclosed in Japanese Unexamined Patent Publication No. 8728 and Japanese Unexamined Patent Publication No. 48-44526 are excellent methods for making an acrylic synthetic fiber flame-retardant. However, since all of them use a solvent, removal, recovery, A purification process is essential and the process as a whole is large-scale. As a result, it cannot be denied that it is economically disadvantageous as a manufacturing method that requires the production of small lots and many brands. However, at present, a manufacturing method that meets these requirements has not yet been found.

[0006]

Means for Solving the Problems As a result of diligent efforts to solve the above problems, the present inventors have found that an acrylonitrile-based copolymer containing vinyl chloride and / or vinylidene chloride as an essential comonomer is used as a plasticizer in a polymer melt. Body, or by a method for producing a flame-retardant acrylonitrile-based synthetic fiber characterized by melt-spinning a mixed melt obtained by adding a flame retardant to the melt, the same or more flame retardancy as compared to the conventional The inventors have found a method for inexpensively producing the flame-retardant acrylic synthetic fiber and have achieved the above-mentioned object. Hereinafter, the present invention will be described in detail.

The acrylonitrile (hereinafter sometimes abbreviated as AN) copolymer used in the present invention has a plasticity of melting water as a plasticizer as long as vinyl chloride and / or vinylidene chloride is an essential comonomer. There is no particular limitation so long as it is a copolymer with another known monomer.
When it is necessary to carry out spinning at a relatively low melt spinning temperature or the whiteness of the final product is particularly important, a polymer having an acrylonitrile ratio of 95% by weight or less is preferable.

The comonomers used for copolymerization include
There is no particular limitation as long as it can be copolymerized with the system of acrylonitrile and vinyl chloride and / or vinylidene chloride. Methyl acrylate, methyl methacrylate, vinyl acetate, sodium methallyl sulfonate, sodium sulfopropyl methacrylate, parastyrene Sodium sulfonate, acrylamide, methacrylamide, vinyl bromide, vinylidene bromide, etc. used for the purpose of improving the dyeability and other physical properties, and a polymerizable emulsifier can be used. Also, AN
The ratio of the essential comonomer (vinyl chloride and / or vinylidene chloride) and other comonomer is 50% by weight or more for AN to obtain the unique texture of acrylic fiber, and 10% by weight for good flame retardancy. If it is above, it will not specifically limit.

Next, regarding the ratio of the AN copolymer and water as a plasticizer, when the water content is 15% by weight or less, the higher the water content is, the lower the melting point is. However, when the water content is 10% by weight or less, the melting point is 180 ° C. or more. And the polymer is markedly colored. When it is 15% by weight or more, the influence of the water content is small and the melting point becomes almost constant. Therefore, the water content in the polymer is 15% by weight.
The above is preferable, but if the water content is too high, the productivity is lowered, so the range of 10% by weight to 25% by weight is preferable. In addition, the melting point defined here refers to a melting point measured by a melting point measuring device (MM-2 type manufactured by Shimadzu Corporation).

In the present invention, not only the flame retardant AN copolymer alone but also a mixed melt obtained by adding a flame retardant to the AN copolymer can be adopted, and the flame retardant used may have a flame retardant effect. There is no particular limitation, and inorganic metal compounds such as antimony trioxide and metastannic acid, aromatic halides such as hexabromobenzene, aliphatic halides such as chlorinated paraffin, and tris (2,3-dibromopropyl) Halogen-containing phosphide such as phosphate,
Examples thereof include organic phosphorus compounds such as dibutylaminophosphate and inorganic phosphorus compounds such as ammonium polyphosphate. The above flame retardants are used alone or in combination thereof, but flame retardancy is improved by adding 0.4% by weight or more to the acrylonitrile-based copolymer, and the flame retardant effect is increased by increasing the addition amount. Get bigger. 0.4% by weight
If the amount is less than the above, the effect is not clear, and if it exceeds 20% by weight, the properties of the fiber are adversely affected and it is economically disadvantageous.

As the melt spinning method, a known melt extrusion device such as a screw type or piston type extruder can be used. The melt extrusion method is used to extrude from the pores, but when extruded into the atmospheric pressure, it is melted. It is necessary to extrude into a pressurized atmosphere because the water in the body is foamed by explosive evaporation.

[0012]

[Function] Water acts on polyacrylonitrile as a plasticizer because water, which cannot maintain its properties as structural water at high temperature, exhibits the original properties of water molecules, such as DMF and DMSO.
It seems that it is to cut off the interaction between cyano groups as well as.

[0013]

EXAMPLES Examples will be shown below for facilitating the understanding of the present invention, but before that, a method for evaluating the flame retardancy of fibers will be described. The flame retardancy is evaluated by the oxygen index method (JIS K7201).
-1972). The oxygen index method measures the minimum oxygen concentration required to continue combustion by changing the mixing ratio of oxygen and nitrogen, and generally, the flame retardancy of a fiber is evaluated in the state of the woven fabric, but in the woven fabric, Since the flame retardancy varies depending on the number of twists, the thickness, the number of threads, etc. of the yarn, and it is difficult to evaluate the flame retardancy of the fiber itself, the filament is twisted according to the method disclosed in JP-A-53-28728. Was applied to prepare a rope-shaped sample, which was evaluated by the oxygen index method. That is, 5 filaments of 2.5 denier 100 filaments are twisted, and this is heat set to stand upright in the holder of the oxygen index tester.
The percentage of oxygen required for this sample to continue to burn 5 cm was measured.

Example 1 70% by weight of a copolymer consisting of 90% by weight of acrylonitrile and 10% by weight of vinyl chloride and 20% by weight of water were melted at 150 ° C., and 10% by weight of various flame retardants as shown in Table 1 were added thereto. %
Was added to prepare a spinning melt. Next, this melt was spun in a saturated steam of ² kg / cm ² at a speed of 30 m / min from a spinneret having 100 holes using an extruder type spinning device, and then stretched 4 times in boiling water to 120 m / min. Single filament denier 2.5, total denier 250 filament bundles were obtained at a rate of minutes. The flame retardancy of each of the obtained samples was evaluated by the oxygen index method described above. As is clear from Table 1 described together, the addition of zinc oxalate, zinc phosphate, and zinc borate increases the oxygen index and improves the flame retardancy in comparison with those without addition. Was given.

[0015]

Example 2 Copolymer 80 consisting of 80% by weight of acrylonitrile, 10% by weight of vinylidene chloride and 10% by weight of methyl acrylate
% By weight and 20% by weight of water were melted at 165.degree. C., and halogenated phosphoric acid ester was added to this to prepare a spinning melt.
Next, this melt was spun in a saturated steam of ² kg / cm ² at a speed of 30 m / min from a spinneret having 100 holes using an extruder type spinning device, and then drawn 4 times in boiling water to 120 m / min. A filament bundle of short fiber denier 2.5 and total denier 250 was obtained at a speed of minutes. The flame retardancy of each of the obtained samples was evaluated by the oxygen index method described above. Table 2
As is clear from the above, the addition of halogenated phosphoric acid ester in an amount of 0.4% by weight or more increased the oxygen index and showed an improvement in flame retardancy as compared with the non-added one. %, It was confirmed that the dye adsorbed on the phosphate portion was discolored as a result of dyeing the filament bundle.

[0017]

COMPARATIVE EXAMPLE 1 80% by weight of a copolymer consisting of 90% by weight of acrylonitrile and 10% by weight of methyl acrylate and 16% of 20% by weight of water.
The spinning melt was prepared by melting at 5 ° C. Next, this melt was spun in a saturated steam of ² kg / cm ² at a speed of 30 m / min from a spinneret having 100 holes using an extruder type spinning device, and then drawn 4 times in boiling water to 120 m / min.
A filament bundle of short fiber denier 2.5 and total denier 250 was obtained at a speed of minutes. The flame retardancy of each of the obtained samples was evaluated by the oxygen index method described above. As a result, the sample burned at an oxygen index of 20 and was at a low level as compared with the results of Tables 1 and 2.

Comparative Example 2 The polymer of Example 1 was dissolved in dimethylformamide to prepare a 20% stock solution for spinning, which was spun out from a spinneret having 100 holes at 40 ° C. into a 55% aqueous dimethylformamide solution, followed by boiling water. The film is stretched 7 times in the same room and washed at the same time, and then treated in saturated steam at 140 ° C for 5 minutes to 30%.
It was shrunk to obtain a filament bundle of short fiber denier 2.5 and total denier 250. The flame retardancy was moderate with an oxygen index of 22.8, but the residual DMF concentration in this filament was 0.5% by weight with respect to the weight of the fiber, and there is some concern about skin damage to the human body. It was In addition, spinning was attempted by adding zinc oxalate as a flame retardant to the spinning dope in an amount of 1% by weight based on the amount of the polymer.

[0020]

As described above, the method of the present invention produces a flame-retardant acrylonitrile-based synthetic fiber by melt spinning using water as a plasticizer. Not only skipped the process,
It has the same or higher flame retardancy than conventional ones,
Moreover, the fact that a process capable of inexpensively producing a flame-retardant acrylonitrile-based synthetic fiber overcoming the problem of safety due to a residual solvent is a remarkable effect of the present invention, which has great industrial significance. is there.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuichi Kasahara 3-1-112 Kanaokahigashi-cho, Okayama-shi, Okayama

Claims (1)

[Claims] 1. Melt spinning of a polymer melt of an acrylonitrile copolymer having vinyl chloride and / or vinylidene chloride as an essential comonomer as a plasticizer, or a mixed melt obtained by adding a flame retardant to the melt. A method for producing a flame-retardant acrylonitrile-based synthetic fiber, which is characterized.