CN1297697C - Flameproof polyacrylonitrile fibre and method for preparing same - Google Patents

Abstract

The invention discloses a flame-retardant polyacrylonitrile fiber and a manufacturing method thereof. The fiber at least includes an APP flame retardant with a polyacrylonitrile content of 5wt% to 25wt%, or passes through a silane coupling agent or a titanate coupling agent. Treated APP flame retardant, the fiber can further include polyol compounds such as pentaerythritol and dipentaerythritol, the amount of polyol compound meets APP/polyol: 2～3.8 (wt/wt); the flame retardant and one-step method Or the inorganic solvent spinning stock solution blending of the polyacrylonitrile that the two-step method makes, is mixed with the blended spinning stock solution, then adopts the method for the inorganic solvent spinning route of prior art to manufacture acrylic fiber, through spinning, washing, drafting and heating A sizing process obtains the fibers. In the invention, the cheap, easy-to-obtain, non-toxic, high-efficiency, and widely used inorganic additive flame retardant APP is used to spin the flame-retardant acrylic fiber, the obtained blended spinning stock solution has good spinnability, and the obtained fiber has good flame retardancy.

Description

Flame-retardant polyacrylonitrile fiber and its manufacturing method

field of invention

The invention relates to a flame-retardant fiber material—flame-retardant polyacrylonitrile fiber and a manufacturing method thereof, in particular to a flame-retardant polyacrylonitrile fiber containing ammonium polyphosphate flame retardant and spun by an inorganic solvent and a manufacturing method thereof.

Background technique

Polyacrylonitrile fiber (commonly known as acrylic fiber) has the advantages of high bulkiness, comfortable hand feeling, good heat retention, and easy dyeing. It is widely used in clothing, daily decorations, and industrial applications. But its biggest disadvantage is that it is easy to burn, and it produces highly toxic hydrogen cyanide, etc., so its application is limited in many occasions requiring flame retardancy.

At present, there are three main methods for producing flame-retardant acrylic fibers in the world, namely finishing method, copolymerization method and blending method. The post-finishing method includes surface flame-retardant coating of fibers and fabrics, and chemical modification of molecular chains of gel filaments and fibers. Surface coating finishing is the earliest and most convenient flame retardant modification method, but the washing resistance is not good, the flame retardant effect is not durable, and the hand feeling of fibers and fabrics after flame retardant finishing is deteriorated; chemical modification of molecular chains Including carboxylation and salinization of -CN group, crosslinking or cyclization of molecular chains, flame retardant elements or groups grafted on molecular chains, etc. These methods increase the post-processing and finishing process of fibers, and the flame retardant performance is not significantly improved or It may lead to some performance degradation, and the process is complicated or the technical conditions are high. In addition, finishing method is also easy to cause environmental pollution.

The copolymerization method is to copolymerize acrylonitrile monomer with flame retardant monomers such as vinyl chloride and vinylidene chloride to prepare a flame retardant copolymer containing flame retardant elements such as halogen and phosphorus, and then spin it into shape. The flame retardant method used in the product is typically represented by acrylic chloride fiber. This kind of flame-retardant acrylic fiber has excellent flame-retardant performance and long-lasting flame-retardant effect. However, the copolymerization method has the following disadvantages: compared with conventional acrylic fiber, the polymerization and spinning production process must be changed; when using inorganic solvent spinning, the flame retardant monomer content in the inorganic solvent-soluble interpolymer is generally lower than 20wt% ~25wt%, it is difficult to meet the flame retardant requirements, and when using organic solvents, although the flame retardant monomer content in the copolymer can be increased to more than 45wt%, it will cause heat resistance, light resistance, fiber dimensional stability and dyeability of the polymer Deterioration of excellent properties such as copolymers; water phase polymerization is generally used for the preparation of copolymers, but many flame retardant monomers such as vinyl halides have low water solubility and high volatility, which makes the polymerization reactivity and polymerization rate low, and also brings certain problems to production operations. difficulty.

The blending method is to blend polyacrylonitrile with low-molecular or high-molecular additive flame retardants in a solvent, usually by blending additive flame retardants into the original polyacrylonitrile spinning stock solution, preparing blended spinning stock solution and then spinning Silk. Generally, although the flame retardant effect of the blending method is inferior to that of the copolymerization method, it does not affect the original polymerization process and the preparation of the spinning stock solution. If a suitable additive flame retardant is selected, the spinning process conditions and fiber Compared with the original acrylic fiber, the physical and mechanical properties have no obvious change, and the process is simple, the application is wide, and the production is flexible. However, since the flame retardant content in the blended flame-retardant acrylic fiber should not be too high, it is necessary to select an efficient flame retardant, and the selection of the flame retardant should also consider its solubility or uniform and stable dispersion in the spinning dope , Compatibility with polyacrylonitrile, retention rate and washing resistance in the fiber manufacturing process, etc.

The prior art uses polyacrylonitrile and polyvinyl chloride, poly(vinyl chloride-vinylidene chloride) and other halogen-containing flame-retardant polymers to blend and spin, but these flame-retardant polymers are poorly compatible with polyacrylonitrile and affect Fiber properties, while being limited by the amount of addition, it is impossible to make acrylic fibers with high flame retardancy by this method.

Guangdong Chemical Fiber (3): 1 ~ 14 (1989) reported the use of FR8 (octabromodiphenyl ether), Melliand Textilberichte72 (5): 353 ~ 359 (1991) reported the use of (poly) acrylate containing phosphate groups , DE4005376A1 discloses the phosphoric acid ester that adopts polyphenol, DE4026883A1 and Patent Publication No. 57-30146 disclose the method that adopts polyphosphazine containing organic groups as flame retardant and polyacrylonitrile to blend and spin flame-retardant acrylic fiber, but its neither Organic solvents such as dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) are used as spinning solvents, and when inorganic solvents such as sodium thiocyanate (NaSCN) aqueous solution are used as spinning solvents, due to these barriers The flame retardant is insoluble in the spinning stock solution, and it cannot be uniformly and stably dispersed. After the flame retardant is mixed with the spinning stock solution, it will block the filter screen and the spinneret hole, resulting in spinning and drafting. Burning acrylic. On the other hand, the above-mentioned (poly)acrylates containing phosphate groups and phosphate esters of polyphenols are either not commercially available or relatively expensive.

Journal of South China University of Technology (Natural Science Edition) 24(7): 121～127(1996) reported that ammonium dihydrogen phosphate and urea were used as composite flame retardants and polyacrylonitrile/sodium thiocyanate-water spinning stock solution homogeneously A technical scheme for blending and spinning flame-retardant acrylic fibers. However, both ammonium dihydrogen phosphate and urea are water-soluble substances. Although they can be homogeneously blended with the spinning dope, the flame retardant will be seriously lost during the fiber manufacturing processes such as coagulation, stretching, and washing, and cannot be obtained. Flame retardant fiber is expected, and because the flame retardant has poor washing resistance, the flame retardant durability of the resulting fiber is not good. The researchers of the present invention found that when the total amount of flame retardant added was 20 wt% of polyacrylonitrile, the limiting oxygen index (LOI value) of the obtained acrylic fiber was only 21, and the flame retardant performance was not significantly improved.

GB1590619 discloses a technical scheme of tetrabromophthalic anhydride (PHT4) and halogen-containing flame-retardant acrylonitrile copolymer blended and spun with DMF as a solvent to improve the flame retardancy of fibers. PHT4 is soluble in DMF, but insoluble in inorganic solvents such as NaSCN aqueous solution, and cannot be uniformly and stably dispersed in inorganic solvent spinning stock solution, so it is difficult to use inorganic solvent spinning for this scheme. At the same time, as confirmed in this patent, if PHT4 is blended with non-flame-retardant polyacrylonitrile, the flame-retardant efficiency is very low, and flame-retardant acrylic fibers with good performance cannot be obtained.

Published Patent Publication Zhao 63-59410 discloses a technical solution for blending and spinning aluminum salts such as aluminum nitrate soluble in inorganic solvents such as NaSCN aqueous solution and halogen-containing flame-retardant acrylonitrile copolymers in inorganic solvents to improve the flame retardancy of fibers . However, these aluminum salts need to be mixed in the slurry before the acrylonitrile copolymer is heated and dissolved in the solvent, rather than directly mixed into the polymer solution or spinning dope, and the pH value needs to be adjusted to 6.0, preferably 4.0 After that, reheat and dissolve to make blended spinning stock solution, which is inconsistent with the usual one-step production process of acrylic fibers and is not conducive to production operations. Furthermore, the aluminum salt promotes the flame-retardant performance of the flame-retardant acrylonitrile copolymer, but its own flame-retardant efficiency is very low, and when it is blended with non-flame-retardant polyacrylonitrile, the performance cannot be obtained. Good flame retardant acrylic.

On the other hand, at the scene of a fire, smoke is the first and most lethal factor that delays the timing of fire fighting, so the contemporary "flame retardant" is comparable to "smoke suppression". When acrylic fiber burns, whether it is smoldering or flaming, it releases a lot of smoke. The current flame-retardant acrylic products are mainly halogen-containing products, which not only produce toxic hydrogen halide gas, etc., but also further aggravate the formation of smog when burned.

Journal of Applied Polymer Science 27 (9): 3369-3377 (1982) studied the effect of APP on polyacrylonitrile by dry mixing ammonium polyphosphate (APP) powder with polyacrylonitrile resin, and the results showed that APP has an effect on polyacrylonitrile Good flame retardancy and smoke suppression effect. But this document does not refer to polyacrylonitrile fibers.

APP is an inexpensive, non-toxic, highly efficient, and widely used inorganic additive flame retardant. However, when it is used to spin flame-retardant acrylic fibers, it cannot be used well because it is insoluble in common organic solvents for polyacrylonitrile. Dispersed, it is difficult to use organic solvents for spinning; APP with a low degree of polymerization has good water solubility and is soluble in the usual inorganic solvent spinning stock solution of polyacrylonitrile, but it will cause a large amount of APP to be lost during the fiber manufacturing process, and the resistance of the obtained fibers Flammability and flame-retardant durability are poor; although APP with a high degree of polymerization overcomes the disadvantage that APP with a low degree of polymerization is easy to dissolve in water, it has low solubility or even insoluble in the usual inorganic solvent spinning stock solution of polyacrylonitrile. When blending spinning dope with solvent, APP fine powder not only cannot be uniformly and stably dispersed, but also produces large hard particles, which seriously affects the spinnability of blending spinning dope.

Furthermore, at present, most acrylic fiber factories in the world use the spinning route of inorganic solvents such as NaSCN aqueous solution. Using this spinning route, the flame retardant is mixed into the original polyacrylonitrile spinning stock solution to produce flame-retardant acrylic fiber. , which is more in line with the needs of actual production.

Contents of the invention

The purpose of the present invention is to provide a flame-retardant polyacrylonitrile fiber, which has good physical and mechanical properties, flame-retardant performance and flame-resistant durability, and has less smoke when burned, and has low production cost.

Another object of the present invention is to provide a manufacturing method of flame-retardant polyacrylonitrile fiber, the manufacturing method is to blend the flame retardant with the inorganic solvent spinning stock solution of polyacrylonitrile, adopt the existing inorganic solvent spinning The acrylic fiber manufacturing method of the route has the advantages of simple process, flexible production and close combination with actual production.

In order to achieve the above object, the technical solution adopted in the present invention is that a flame-retardant polyacrylonitrile fiber at least includes APP flame retardant with an amount of polyacrylonitrile of 5wt%-25wt%.

The degree of polymerization of the APP flame retardant is at least 50, and the particle size is less than or equal to 3 μm. Preferably, the degree of polymerization is at least 100, and the particle size is less than or equal to 1 μm. In the blended spinning dope prepared by blending APP and spinning dope, the content of APP is preferably 10wt%-20wt% of polyacrylonitrile.

The APP may also be APP treated with a surface treatment agent. The surface treatment agent is silane coupling agents such as γ-aminopropyl triethoxysilane (KH550), methacryloxypropyl trimethoxysilane (KH570), isopropyl tri(dioctyl coke One of titanate coupling agents such as phosphoryloxy) titanate (NDZ201). The surface treatment agent can be used for surface treatment according to the usual treatment method of inorganic powder. Surface treatment can improve the compatibility of APP and polyacrylonitrile, and improve the physical and mechanical properties and flame retardancy of the obtained fibers.

Flame-retardant polyacrylonitrile fiber of the present invention also comprises a kind of polyol compound, and described polyol compound is pentaerythritol (PER), dipentaerythritol (DPER) and other polyol compounds suitable for the present invention, and the amount of polyol compound is APP/PER (or DPER) is 2-3.8 (wt/wt). The same as when APP is used in plastics, coatings, etc., the polyol compound can further improve the flame retardancy efficiency of APP and improve the flame retardancy of polyacrylonitrile fibers.

Preferably, the amount of the polyol compound is such that APP/PER (or DPER) is 2.5-3 (wt/wt).

The manufacturing method of the flame retardant polyacrylonitrile fiber of the present invention comprises mixing the flame retardant with an inorganic solvent to obtain a flame retardant slurry, and then blending with the polyacrylonitrile spinning stock solution using the same inorganic solvent to obtain the required flame retardant The blended spinning stock solution with the fuel concentration, and then the fibers are obtained through processes such as spinning, coagulation, washing, drafting and heat setting in the prior art.

The method for mixing the flame retardant with the inorganic solvent is to stir and mix the flame retardant with 3 to 5 times its weight of the same inorganic solvent as the spinning dope solvent at room temperature to obtain a flame retardant slurry.

The polyacrylonitrile described in the present invention is an acrylonitrile copolymer commonly used for spinning acrylic fibers, that is, a copolymer of acrylonitrile monomers and other unsaturated monomers that can be copolymerized with it, wherein other unsaturated monomers include halogen-free and phosphorus non-flame retardant vinyl monomers and flame retardant vinyl monomers containing halogen or/and phosphorus. These unsaturated monomers include acrylic acid, methacrylic acid and their esters; acrylamide and its alkyl substitutes; vinyl acetate, vinyl stearate and other carboxylic acid vinyl esters; vinyl sulfonic acid, methacrylic acid non-flame retardant monomers such as acid, unsaturated sulfonic acid such as acrylamide methyl propane sulfonic acid and its salts, and the following flame retardant monomers: vinyl chloride, vinyl bromide, vinylidene chloride, methyl Halogen-containing vinyl monomers such as dibromopropyl acrylate; phosphorus-containing vinyl monomers such as diethylallyl phosphate and diethyl phosphoacrylate; bis(2-chloroethyl) vinyl phosphate, Diethyl-2-bromopropenyl phosphate and other halogen-containing and phosphorus vinyl monomers, etc.

The above monomers can be polymerized by free radical polymerization to obtain the acrylonitrile copolymer, and the method or polymer product is well known to those skilled in the art.

In the acrylonitrile copolymer, the content of the acrylonitrile monomer is 50wt% to 98wt%, preferably 65wt% to 96wt%; the content of other non-flame retardant monomers is 2wt% to 50wt%, preferably 4wt% to 35wt%; The content of flammable monomer is 0-25wt%, preferably 0-20wt%.

Inorganic solvent of the present invention, can adopt the inorganic solvent in existing acrylic fiber spinning technology, as the aqueous solution of thiocyanates such as NaSCN, potassium thiocyanate (KSCN), ammonium thiocyanate (NH ₄ SCN); Chlorination Aqueous solutions of chlorides such as zinc and calcium chloride, etc. Aqueous NaSCN and aqueous zinc chloride are preferred, and aqueous NaSCN is most preferred.

The inorganic solvent spinning stock solution of polyacrylonitrile of the present invention can adopt the spinning stock solution of above-mentioned inorganic solvent in the existing acrylic fiber manufacturing technology, both can be the spinning stock solution of acrylic fiber one-step spinning process, also can be acrylic fiber two-step Spinning dope for spinning process. One-step spinning stock solution is the spinning stock solution obtained by monomer removal after the reaction monomer is polymerized in the solvent; the two-step spinning stock solution is the spinning stock solution obtained by re-dissolving the polymer after the reaction monomer is polymerized. stock solution.

In order to improve the flame retardant efficiency of APP, just like when it is used in plastics and coatings, when APP is blended with spinning dope to prepare blended spinning dope, pentaerythritol (PER), dipentaerythritol (DPER) or suitable Other such polyol compounds of the present invention. In this case, the APP/PER (or DPER) in the blended spinning stock solution is 2-3.8 (wt/wt), preferably 2.5-3 (wt/wt).

The blended spinning stock solution in the present invention refers to the blended spinning stock solution prepared by mixing the inorganic solvent spinning stock solution of polyacrylonitrile prepared by the usual method (one-step method or two-step method) and the above-mentioned flame retardant. The preparation of the blended spinning stock solution is to mix the flame retardant with 3 to 5 times the weight of the inorganic solvent (the same solvent as the spinning stock solution) to obtain a flame retardant slurry, and then mix the obtained slurry with a certain amount of spinning Stir the silk stock solution to mix. First, stir at room temperature for 10 minutes to 20 minutes, then slowly raise the temperature to 60° C. to 70° C. under stirring, and continue stirring at this temperature for 10 minutes to 20 minutes. Stir preferably at room temperature for 10 minutes, then raise the temperature to 40°C to 50°C at a heating rate of 2 to 3°C/min under stirring, then raise the temperature to 60°C to 70°C at a heating rate of 1 to 2°C/min, and Stirring was continued at this temperature for 15 minutes. After defoaming, the blended spinning stock solution with the required flame retardant concentration is obtained.

The manufacture method of the flame-retardant polyacrylonitrile fiber of the present invention can adopt the existing inorganic solvent spinning route to manufacture the method for acrylic fibers, that is to say, the blended spinning stock solution of the above-mentioned gained is subjected to usual spinning, coagulation, washing, drafting and heating The fibers are obtained by processes such as shaping. These methods have been fully disclosed in the prior art, for example, see Fang Jun, Wu Guoming, Mei Qianfang, etc., "Research on Non-halogen Flame Retardant Acrylic Fiber Spinning by NaSCN Solvent Method", Journal of South China University of Technology (Natural Science Edition), 24 (7), 121-127 (1996), Fujimatsu Masaki, Miura Mitsuo, "Manufacturing method of flame-retardant Acryl fiber", published patent publication Sho 63-59410 (1988), Ohara Kunio, Mitamura Hideyuki, "Fire-resistant inorganic acidification "Production method containing viscous liquid", Patent Publication No. 57-45763 (1982), but the present invention is not limited to the methods listed in the published documents.

The flame-retardant polyacrylonitrile fiber of the present invention can be a fiber with a circular cross-section or a fiber with a special-shaped cross-section, and the special-shaped cross-section includes flat, triangular, trilobal, dumbbell and the like. Fibers of different cross-sections can be obtained by changing the shape of the spinneret holes.

When the flame-retardant polyacrylonitrile fiber is manufactured according to the above method, since APP can be uniformly and stably dispersed as fine particles in the spinning stock solution, and polyol compounds such as PER and DPER can be dissolved in the spinning stock solution, the resulting blended spinning stock solution has good properties. Excellent spinnability; because APP and polyol compound are evenly distributed in fine particles in the finished fiber, and the particles fill some cavities in the fiber, so the obtained fiber has good physical and mechanical properties; because APP is an intumescent flame retardant It has a high content of phosphorus and nitrogen. When it is heated, it dehydrates and generates ammonia, non-volatile phosphorus oxides and polyphosphoric acid. Polyphosphoric acid further carbonizes polyacrylonitrile to form an expanded phosphorus-carbon layer covering base. The ammonia gas generated at the same time isolates and dilutes the oxygen in the air, the addition of polyols promotes the formation of the carbon layer, and the TiO ₂ and SiO ₂ generated by the coupling agent for processing APP improve the thermomechanical properties of the phosphorus-carbon layer, thus The obtained fiber has good flame retardant properties, and produces less smoke when burned; due to its high degree of polymerization, APP has low or insoluble solubility in water, and is also insoluble in common organic solvents. It has a high retention rate in the finished fiber and is resistant to washing. Good performance, so the obtained fiber also has good flame resistance and durability.

Detailed ways

The following are specific examples of the present invention, and the described examples are used to describe the present invention, rather than limit the present invention. Except for elongation at break, the percentages in the examples are by weight. The test method of LOI is to measure the LOI according to the GB/T 5454-1997 method after laying the fiber into a non-woven fabric (150g/m ² ) to characterize the flame retardancy of the fiber; the test of breaking strength and elongation at break The method is GB/T 14337-1993; the test method for fineness is GB/T 14335-1993.

Example 1

The polyacrylonitrile spinning stock solution using NaSCN aqueous solution as solvent was prepared by the usual method. The composition of polyacrylonitrile is: 91.5% of acrylonitrile, 7.0% of methyl acrylate, and 1.5% of sodium methacrylate. The concentration of polyacrylonitrile in the spinning dope is 13%, and the concentration of NaSCN is 45%. APP (polymerization degree 200, Jiangsu Zhenjiang Xingxing Flame Retardant Factory) with 15% polyacrylonitrile content was mixed with the above-mentioned NaSCN aqueous solution to obtain APP slurry. Stir and mix the obtained slurry with the spinning stock solution, first stir at room temperature for 10 minutes, then raise the temperature to 45°C at a heating rate of 2.5°C/min under stirring, and then raise the temperature to 65°C at a heating rate of 1.5°C/min, And continue to stir at this temperature for 15 minutes, and obtain the blended spinning stock solution through defoaming. Using a spinneret with a spinneret diameter of Φ0.06mm, using a NaSCN aqueous solution with a concentration of -1°C and a concentration of 13% as a coagulation bath, the resulting blended spinning stock solution is subjected to spinning, coagulation, washing, drafting and heat setting according to conventional methods. A flame-retardant polyacrylonitrile fiber is obtained. The blended spinning dope has good spinnability, the fineness of the obtained fiber is 2.2dtex, the breaking strength is 2.3cN/dtex, the breaking elongation is 26%, the LOI is 25.8, and the fiber generates less smoke when burning. After 20 times of alkali washing (NaOH concentration 0.1mol/L, temperature 90°C, 2 min each time) and 25 times water washing (water temperature 95°C, 20 min each time), the LOI was 25.3.

Comparative Example 1

The same as Example 1, the difference is that the spinning dope is not mixed with the flame retardant, but is spun directly, the LOI of the obtained fiber is only 18.4, and the amount of smoke generated during combustion increases by nearly 2 times.

Example 2

Others are the same as in Example 1, except that APP has been surface-treated with KH550 in advance. The blended spinning dope has good spinnability, the obtained fiber has a fineness of 2.2dtex, a breaking strength of 2.5cN/dtex, a breaking elongation of 29%, and an LOI of 26.4.

Example 3

Others are the same as in Example 2, except that PER is added in the blended spinning stock solution. The amount of PER is 40% of APP. The blended spinning solution has good spinnability, the obtained fiber has a fineness of 2.3dtex, a breaking strength of 2.4cN/dtex, a breaking elongation of 29%, and an LOI of 27.5.

Example 4

Others are the same as in Example 1, except that the degree of polymerization of the APP used is 700 (Hoechst, Germany), and a spinneret with a spinneret diameter of Φ0.1 mm is used. The blended spinning dope has good spinnability, the obtained fiber has a fineness of 7.6dtex, a breaking strength of 2.1cN/dtex, a breaking elongation of 28%, and an LOI of 26.5. Gained fiber after alkali washing and water washing under the same conditions and times as in Example 1, its LOI was 26.2.

Example 5

Others are the same as Example 4, and the difference is that polyacrylonitrile consists of: 76.5% acrylonitrile, 9.0% methyl acrylate; 14.0% vinylidene chloride, 0.5% sodium methacrylate, and the addition of APP is polypropylene 10% of nitrile. The blended spinning dope has good spinnability, the resulting fiber has a fineness of 6.4dtex, a breaking strength of 2.4cN/dtex, a breaking elongation of 32%, an LOI of 27.1, and less smoke when the fiber is burned.

Comparative Example 2

The same as Example 5, the difference is that the spinning dope is not mixed with the flame retardant, but is spun directly, and the LOI of the obtained fiber is only 21.0, and the amount of smoke generated during combustion increases by nearly 2 times.

Example 6

Others are the same as in Example 5, except that the composition of polyacrylonitrile is 80% of acrylonitrile, 16% of bis(2-chloroethyl) vinyl phosphate, and 4% of methyl acrylate. The blended spinning dope has good spinnability, the obtained fiber has a fineness of 6.7dtex, a breaking strength of 2.3cN/dtex, a breaking elongation of 30%, and an LOI of 28.0.

Comparative Example 3

Same as Example 6, the difference is that the spinning dope is not mixed with the flame retardant, but directly spun, and the LOI of the obtained fiber is only 22.3.

Comparative Example 4

Others are the same as Comparative Example 3, except that the composition of polyacrylonitrile is 70% of acrylonitrile, 26% of bis(2-chloroethyl) vinyl phosphate, and 4% of methyl acrylate. The spinnability of the spinning dope is not good, the resulting fiber fineness is 8.8dtex, the breaking strength is 1.5cN/dtex, the elongation at break is 16%, and the LOI is 25.0.

Example 7

The polyacrylonitrile spinning stock solution using the zinc chloride aqueous solution as the solvent was prepared by the usual method. The composition of polyacrylonitrile was 95.5% of acrylonitrile, 4.0% of methyl acrylate, and 0.5% of sodium methacrylsulfonate. The concentration of polyacrylonitrile in the spinning dope is 13%, and the concentration of zinc chloride is 60%. APP (polymerization degree 700) with a polyacrylonitrile content of 17.5% is pre-treated with KH570, and then mixed with the above-mentioned zinc chloride aqueous solution together with PER (PER content is 40% of APP) to obtain a flame retardant slurry. Stir and mix the obtained flame retardant slurry with the spinning dope, first stir at room temperature for 10 minutes, then raise the temperature to 40°C at a rate of 2°C/min under stirring, and then raise the temperature to 60°C at a rate of 1°C/min , and continue to stir at this temperature for 10 minutes, and obtain the blended spinning stock solution through defoaming. Using a spinneret with a spinneret hole diameter of Φ0.06mm, using a 0°C, 25% zinc chloride aqueous solution as a coagulation bath, the blended spinning stock solution is subjected to spinning, washing, drawing and heat setting in the usual way to obtain a flame retardant Polyacrylonitrile fibers. The blended spinning dope has good spinnability, the obtained fiber has a fineness of 2.9dtex, a breaking strength of 2.1cN/dtex, a breaking elongation of 22%, and an LOI of 28.8.

Example 8

Others are the same as in Example 3, except that the shape of the spinneret hole is dumbbell-shaped and the aspect ratio of the hole is a spinneret of 20:1. The blended spinning dope has good spinnability, and the resulting fiber is flat, with a fineness of 7.0dtex, a section aspect ratio of 7:1, a breaking strength of 1.9cN/dtex, a breaking elongation of 28%, and an LOI of 27.6.

Example 9

Others are the same as in Example 7, except that the composition of polyacrylonitrile is 76.5% of acrylonitrile, 9.0% of methyl acrylate, 14.0% of vinylidene chloride, and 0.5% of sodium methacrylene sulfonate, and the polyacrylonitrile is polymerized by NDZ201 surface treatment. APP with a degree of 100, and its content in the blended spinning dope is 5% of polyacrylonitrile. The blended spinning dope has good spinnability, the resulting fiber has a fineness of 2.0dtex, a breaking strength of 2.6cN/dtex, a breaking elongation of 35%, and an LOI of 25.3.

Example 10

Others are the same as in Example 7, except that APP with a degree of polymerization of 50 is adopted, and its content in the blended spinning stock solution is 25% of polyacrylonitrile, and the PER in the blended spinning stock solution is changed to DPER simultaneously, and the content of DPER is The amount satisfies a weight ratio APP/DPER of 3.8. The blended spinning dope has good spinnability, the resulting fiber has a fineness of 3.2dtex, a breaking strength of 1.8cN/dtex, a breaking elongation of 19%, and an LOI of 29.5.

Example 11

Others are the same as Example 1, except that the composition of polyacrylonitrile is: 98% of acrylonitrile, 1% of methyl acrylate, and 1% of sodium methacrylate. The blended spinning dope has good spinnability, the obtained fiber has a fineness of 2.2dtex, a breaking strength of 2.2cN/dtex, a breaking elongation of 23%, and an LOI of 25.2.

Example 12

Others are the same as Example 1, except that the composition of polyacrylonitrile is: 50% of acrylonitrile, 25% of methyl acrylate, 15% of vinylidene chloride, and 10% of bis(2-chloroethyl) vinyl phosphate. The spinnability of the blended spinning solution is still good, the obtained fiber fineness is 2.6dtex, the breaking strength is 1.8cN/dtex, the breaking elongation is 20%, and the LOI is 30.0.

Claims (15)

1. A flame-retardant polyacrylonitrile fiber, characterized in that said fiber at least comprises APP flame retardant with a polyacrylonitrile amount of 5wt% to 25wt%; said fiber is made by the following method: combining flame retardant with one-step method or the inorganic solvent spinning stock solution of polyacrylonitrile obtained by the two-step method is blended to prepare the blended spinning stock solution, and then the method of manufacturing acrylic fibers by using the inorganic solvent spinning route, and obtaining the obtained polyacrylonitrile through spinning, washing, drawing and heat setting processes fiber. 2. A flame-retardant polyacrylonitrile fiber according to claim 1, characterized in that said polyacrylonitrile is a copolymer of acrylonitrile monomer and other unsaturated monomers, wherein other unsaturated monomers include Non-flame retardant vinyl monomers of halogen and phosphorus and flame retardant vinyl monomers containing halogen or/and phosphorus, the content of acrylonitrile monomer in polyacrylonitrile is 50wt%~98wt%; other nonflame retardant vinyl The content of vinyl monomer is 2wt%-50wt%; the content of flame-retardant vinyl monomer is 0-25wt%. 3. A flame-retardant polyacrylonitrile fiber according to claim 2, characterized in that the content of the acrylonitrile monomer is 65wt% to 96wt%, and the content of other non-flame retardant vinyl monomers is 4wt% to 35wt% %, the flame retardant vinyl monomer content is 0-20wt%. 4. A flame-retardant polyacrylonitrile fiber according to claim 2 or 3, characterized in that said other unsaturated monomers include acrylic acid, methacrylic acid and their esters, acrylamide and their alkyl substitutes , non-flame retardant monomers of vinyl carboxylate, unsaturated sulfonic acid and its salts, and flame retardant monomers of halogen-containing vinyl monomers, phosphorus-containing vinyl monomers, and halogen- and phosphorus-containing vinyl monomers body; the vinyl carboxylate includes vinyl acetate and vinyl stearate, the unsaturated sulfonic acid includes vinyl sulfonic acid, methyl propylene sulfonic acid and acrylamidomethyl propane sulfonic acid, the described containing Vinyl halide monomers include vinyl chloride, vinyl bromide, vinylidene chloride, and dibromopropyl methacrylate, and the phosphorus-containing vinyl monomers include diethylallyl phosphate and diethyl phosphoric acid Acrylic esters, said halogen- and phosphorus-containing vinyl monomers include bis(2-chloroethyl)vinyl phosphate and diethyl-2-bromopropenyl phosphate. 5. A flame-retardant polyacrylonitrile fiber according to claim 1, characterized in that the degree of polymerization of the APP flame retardant is at least 50, and the particle size is less than or equal to 3 μm. 6. A kind of flame-retardant polyacrylonitrile fiber according to claim 5, characterized in that the degree of polymerization of the APP flame retardant is 100, and the particle size is less than or equal to 1 μm; the content of APP is 10wt%-10% of polyacrylonitrile. 20wt% 7. A kind of flame-retardant polyacrylonitrile fiber according to claim 1, 5 or 6, characterized in that said fire retardant is a surface-treated flame retardant, and the surface treatment agent is a silane coupling agent or titanic acid Ester coupling agent. 8. A kind of flame-retardant polyacrylonitrile fiber according to claim 1, 5 or 6, is characterized in that described fiber also comprises polyol compound, and described polyol compound is selected from pentaerythritol, dipentaerythritol, The amount of polyol compound is APP/polyol: 2-3.8wt/wt. 9. A method for manufacturing the flame-retardant polyacrylonitrile fiber according to claim 1, characterized in that the flame retardant is blended with the inorganic solvent spinning stock solution of polyacrylonitrile obtained by the one-step method or the two-step method, and is mixed with a total Blending the stock solution, and then adopting an inorganic solvent spinning route to manufacture acrylic fibers, and obtaining the fibers through spinning, washing, drawing and heat setting processes. 10. manufacturing method according to claim 9 is characterized in that described inorganic solvent adopts the aqueous solution of thiocyanate or the aqueous solution of chloride, and the aqueous solution of thiocyanate is selected from NaSCN, potassium thiocyanate, thiocyanate The aqueous solution of ammonium acid; the aqueous solution of chloride is selected from the aqueous solution of zinc chloride, calcium chloride. 11. The manufacturing method according to claim 10, characterized in that the inorganic solvent is NaSCN aqueous solution or zinc chloride aqueous solution. 12. The manufacturing method according to claim 11, characterized in that the inorganic solvent is an aqueous NaSCN solution. 13. The manufacturing method according to any one of claims 9-12, characterized in that the preparation of the blended spinning stock solution is to first mix the flame retardant with 3 to 5 times its weight of the same inorganic solvent as the spinning stock solution solvent. The solvent is mixed at room temperature to obtain a flame retardant slurry, and then the obtained slurry is stirred and mixed with the spinning dope, first stirred at room temperature for 10 minutes to 20 minutes, and then slowly heated to 60°C to 70°C under stirring, and Stirring is continued at this temperature for 10 minutes to 20 minutes; the blended spinning stock solution with the required flame retardant concentration is obtained through defoaming. 14. The manufacturing method according to claim 13, characterized in that the stirring time at room temperature is 10 minutes, then the temperature is raised to 40°C-50°C at a speed of 2-3°C/min under stirring, and then Raise the temperature to 60°C-70°C at a rate of 1-2°C/min, and continue stirring at this temperature for 15 minutes. 15. The manufacturing method according to claim 9, characterized in that the flame-retardant polyacrylonitrile fiber of circular cross-section is manufactured by changing the shape of the spinneret hole, or the flame-retardant polyacrylonitrile fiber of special-shaped cross-section is manufactured.