阅读说明：本技术 含磷酸甲酯阻燃聚丙烯腈及其制备方法和应用 (Flame-retardant polyacrylonitrile containing methyl phosphate, and preparation method and application thereof ) 是由 董雪 沈志刚 李磊 周勤灼 赵微微 李应成 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种含磷酸甲酯阻燃聚丙烯腈及其制备方法和应用,主要解决目前聚丙烯腈阻燃环境不友好及合成过程复杂、毒性大、难以工业化的问题,通过采用一种含磷酸甲酯的聚丙烯腈共聚物,包括式(I)结构单元和式(II)结构单元：式中,R-1、R-2选自OH、OCH-3中的至少一种,且不同时为OH；R-3任意选自-O-、-NH-中的至少一种；其中,以占所述阻燃聚丙烯腈链段总质量的质量百分数计,式(I)、式(II)结构单元的质量分数分别为98-50％、2～50％的技术方案,较好地解决了该问题,可用于阻燃聚丙烯腈的工业化生产中。。(The invention discloses a flame-retardant polyacrylonitrile containing methyl phosphate, a preparation method and application thereof, mainly solving the problems of the existing polyacrylonitrile that the flame-retardant environment is not friendly, the synthetic process is complex, the toxicity is high and the industrialization is difficult, and by adopting a polyacrylonitrile copolymer containing methyl phosphate, the polyacrylonitrile copolymer comprises a structural unit shown in a formula (I) and a structural unit shown in a formula (II): in the formula, R 1 、R 2 Selected from OH and OCH 3 Not being OH at the same time; r 3 Optional selectionAt least one of-O-, -NH-; the technical scheme that the mass fractions of the structural units in the formula (I) and the formula (II) are respectively 98-50% and 2-50% in percentage by mass of the total mass of the flame-retardant polyacrylonitrile chain segment better solves the problem, and can be used in industrial production of the flame-retardant polyacrylonitrile.)

1. A methyl phosphate-containing polyacrylonitrile copolymer comprising a structural unit of formula (I) and a structural unit of formula (II):

in the formula, R₁、R₂Selected from OH and OCH₃Not being OH at the same time; r₃At least one of-O-, -NH-;

wherein the mass fractions of the structural units in the formula (I) and the formula (II) are respectively 98-50% and 2-50% in terms of the mass percentage of the total mass of the flame-retardant polyacrylonitrile chain segment.

2. The methyl phosphate-containing polyacrylonitrile copolymer according to claim 1, wherein the mass fractions of the structural units of the formula (I) and the formula (II) are 95-60% and 5-40%, respectively.

3. A method for preparing the polyacrylonitrile copolymer containing methyl phosphate described in claim 1 or 2, comprising the following steps:

and (3) carrying out suspension polymerization reaction on acrylonitrile and any methyl phosphate-containing flame retardant monomer selected from the monomers in the formula (II) in the presence of a solvent and an initiator to obtain the flame-retardant polyacrylonitrile powder.

4. The method for preparing the polyacrylonitrile copolymer containing the methyl phosphate according to the claim 3, characterized in that the solvent is at least one of ethylene glycol dimethyl ether, 1, 4-dioxane, acetonitrile or ethanol.

5. The method for preparing polyacrylonitrile copolymer containing methyl phosphate according to claim 3, characterized in that the initiator is azo initiator or peroxide initiator; the azo initiator is preferably at least one of azobisisobutyronitrile, azobisisoheptonitrile, and azobisisobutylamidine hydrochloride, and the peroxide initiator is preferably at least one of dibenzoyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide, and diisopropyl peroxydicarbonate.

6. The method for preparing polyacrylonitrile copolymer containing methyl phosphate according to claim 3, characterized in that the reaction temperature of the polymerization reaction is 60-80 ℃, and the reaction time is preferably 5-24 hours.

7. The method for preparing the polyacrylonitrile copolymer containing the methyl phosphate according to the claim 3, characterized in that in the suspension polymerization process, the total mass of the acrylonitrile and the phosphorus-containing flame retardant monomer is 15-70% by weight of the total weight of the whole reaction solution; the solvent accounts for 85-30%; the initiator accounts for 0.1-1% of the total weight of the acrylonitrile and the phosphorus-containing flame retardant monomer.

8. The method for preparing a polyacrylonitrile copolymer containing methyl phosphate according to claim 3, characterized in that the suspension polymerization is accompanied by stirring.

9. A method of using the methyl phosphate-containing polyacrylonitrile copolymer of claim 1 or 2.

10. Method of application according to claim 9, characterized in that the application is in flame retardant textiles.

Technical Field

The invention relates to the technical field of preparation of flame-retardant polyacrylonitrile. Specifically, the invention relates to halogen-free methyl phosphate-containing flame-retardant polyacrylonitrile, and a suspension preparation method and application thereof.

Technical Field

Polyacrylonitrile is mainly used for preparing polyacrylonitrile fibers. The polyacrylonitrile fiber is fiber spun by polyacrylonitrile or copolymer of acrylonitrile more than 85% and other second and third monomers. Wherein the acrylonitrile content is 35% -85%, the comonomer content is 15% -65% fiber made of copolymer, also called modified polyacrylonitrile fiber. Polyacrylonitrile fiber is one of three major varieties of synthetic fiber, has many excellent properties, plays an important role in both clothing and decoration, and is widely applied in the industrial field. However, the fiber has obvious defects, such as poor flame retardance (the limited oxygen index of polyacrylonitrile is 17-20%), and in order to meet the requirements of people on increasingly higher living standard, the fiber needs to be modified and processed to develop new polyacrylonitrile varieties.

In the aspect of flame-retardant modified polyacrylonitrile, the preparation method mainly comprises the following steps according to the production process and the introduction mode of the flame retardant: blending modification method, copolymerization modification method, thermal oxidation method, post-finishing method and surface chemical grafting modification method. The most industrialized and widely used type of flame-retardant acrylonitrile fiber in the world is acrylonitrile-vinyl chloride copolymer obtained by a copolymerization modification method. The monomers copolymerized therein include: vinyl chloride, vinylidene chloride, and the like. The most typical product, namely the modacrylic produced by the first set of modacrylic production device introduced from Italy in China smoothing organic chemical plants, has the oxygen index of 26-30% and has good flame retardant effect. However, the vinyl chloride-acrylonitrile copolymer has a large smoke amount during combustion, and generates a large amount of harmful gas, such as hydrogen chloride, which is a toxic corrosive gas and causes serious environmental problems, so that the development of a novel environment-friendly worry-free flame retardant is a current research trend. The blending modification method is the most commonly used flame retardant method for polymers, but due to the special processing mode of polyacrylonitrile, the blending modification method needs to consider a plurality of factors such as: the solubility, the dispersibility, the washing fastness and the toxicity of the flame retardant in the spinning solution, whether a spinneret plate is blocked or not and other influencing factors. Therefore, the flame-retardant polyacrylonitrile product prepared by the blending modification method is not produced in large scale at present. The post-finishing method is a flame-retardant method widely used for medical use on various fibers, and has the advantages of simple process, high universality, short production period and quick response. However, the greatest disadvantage of this method is that it is not water-fast, which greatly limits the application of this method. The thermal oxidation method and the surface chemical grafting modification method have certain application in industry, and the mass production is not as good as that of modacrylic, but the effect is better. Both methods, however, destroy the mechanical properties and color of the fibers to some extent. Therefore, in conclusion, the flame retardant method utilizing copolymerization modification has important significance in improving the flame retardant property of the product from the source.

Phosphorus-containing flame retardants are typically the most promising class of flame retardants to replace halogen-based flame retardants. A few reports have been made on the structure of phosphorus-based copolymerized flame-retardant polypropylene nitrile, for example, Wyman et al disclose a preparation method of a styryl phosphate and a copolymer copolymerized with acrylonitrile (Paul Wyman, Vincent Crook, John Ebdon, Barry Hunt and Paul Joseph. Polymer International,2006(55):764 771). However, on the one hand, the polymerization method is too long and requires 48 hours of reaction time, on the other hand, the solvent consumption is about more than 80% of the total mass, and the final polymer powder needs to be precipitated by distilled water, so the operation is complicated and the method is not suitable for large-scale industrial production. Ren et al disclose a preparation method of P, S-containing vinyl flame retardant and a preparation method of a copolymer thereof copolymerized with acrylonitrile (CN 101113211B; Yuanlin Ren, Bowen Cheng, Lin Xu, Aibing Jiang, Youcai Lu. journal of Applied Polymer Science,2010(115): 1489-1494). However, in the method, the O-alkylacrylamide dialkyl thiophosphate is obtained by the reaction of N-hydroxyalkyl acrylamide and dialkyl thiophosphoryl chloride, the preferred dialkyl thiophosphoryl chloride is dimethyl thiophosphoryl chloride, and the chemical reagent belongs to the controlled commodity: highly toxic chemicals. Due to its own highly toxic properties, it will have serious environmental problems during use and after-treatment of products, thus limiting its wide application. And secondly, quaternary copolymerization is adopted, and vinyl acetate or methyl acrylate and the like are added to improve the spinning performance of the stock solution, so that the polymerization process becomes more complicated, the monomer recovery difficulty is improved, and the industrial popularization is not facilitated. In addition, a process for the preparation of copolymers of vinylphosphonic acid and acrylonitrile is disclosed (CN 104725562A; Choon Ho Park, san g Yong Nam, Yong Moo Lee, Journal of Applied Polymer Science,1999(74): 83-89). However, the vinylphosphonic acid is a monomer with high rigidity, and when the content of the vinylphosphonic acid is too high, the polymerization efficiency is reduced, so that the introduction rate of the vinylphosphonic acid is reduced, and on the other hand, the molecular chain rigidity is too high, so that the subsequent spinning is not suitable. Bank et al disclose the preparation of copolymers of diethylvinylphosphonate and acrylonitrile (Mavis Bank, John R Ebdon, and Michael Johnson. Polymer,1994(35): 3470-. The flame retardant performance of the polymer prepared by the method is good (the limiting oxygen index is 27.5 percent), and the reaction yield of the polymer is 42 percent.

Disclosure of Invention

The invention aims to solve the technical problems that a phosphorus-containing monomer is copolymerized and introduced in the prior art, a flexible monomer is required to be introduced, the introduction rate of the phosphorus-containing monomer is high, and the reaction yield of a polymer is low, and provides a methyl phosphate-containing polyacrylonitrile copolymer.

The second technical problem to be solved by the present invention is to provide a method for preparing a polyacrylonitrile copolymer containing methyl phosphate corresponding to the first technical problem.

The present invention is also directed to a method for using the polyacrylonitrile copolymer containing methyl phosphate corresponding to one of the above-mentioned problems.

In order to solve one of the above technical problems, the invention adopts the technical scheme that: a methyl phosphate-containing polyacrylonitrile copolymer comprising a structural unit of formula (I) and a structural unit of formula (II):

in the formula, R₁、R₂Selected from OH and OCH₃Not being OH at the same time; r₃At least one of-O-, -NH-;

wherein the mass fractions of the structural units in the formula (I) and the formula (II) are respectively 98-50% and 2-50% in terms of the mass percentage of the total mass of the flame-retardant polyacrylonitrile chain segment.

In the technical scheme, the mass fractions of the structural units of the formula (I) and the formula (II) are preferably 95-60% and 5-40% respectively.

In order to solve the second technical problem, the invention adopts the technical scheme that: a method for preparing polyacrylonitrile containing methyl phosphate according to any one of the above technical solutions, comprising the following steps:

the method comprises the following steps of carrying out suspension polymerization reaction on acrylonitrile and any methyl phosphate-containing flame retardant monomer in the formula (II) in the presence of a solvent and an initiator to obtain the flame-retardant polyacrylonitrile powder.

In the technical scheme, the obtained flame-retardant polyacrylonitrile powder can be further preferably washed by water and dried to obtain a product.

In the above technical scheme, the solvent is preferably at least one of ethylene glycol dimethyl ether, 1, 4-dioxane, acetonitrile or ethanol; the initiator is preferably an azo initiator or a peroxide initiator, the azo initiator is preferably at least one of azobisisobutyronitrile, azobisisoheptonitrile or azobisisobutylamidine hydrochloride, and the peroxide initiator is preferably at least one of dibenzoyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide and diisopropyl peroxydicarbonate.

In the technical scheme, the reaction temperature of the polymerization reaction is preferably 60-80 ℃, and the reaction time is preferably 5-24 hours.

In the technical scheme, the mass ratio of the acrylonitrile to the flame retardant monomer containing methyl phosphate in the phosphorus-containing polyacrylonitrile copolymer structure is preferably (95.0-60.0%).

In the technical scheme, in the suspension polymerization process, the total mass of the acrylonitrile and the phosphorus-containing flame retardant monomer accounts for 15-70% of the total weight of the whole reaction solution; the solvent accounts for 85-30%; the initiator accounts for 0.1-1% of the total weight of the acrylonitrile and the phosphorus-containing flame retardant monomer.

In the above-mentioned embodiment, the suspension polymerization is preferably carried out with stirring.

In order to solve the third technical problem, the invention adopts the technical scheme that: an application method of polyacrylonitrile obtained from phosphoric acid methyl ester in the technical scheme for solving the technical problem.

In the above technical solutions, the application method is not particularly limited, for example, but not limited to, the application in flame retardant textiles.

The invention has the following advantages:

1. the flame-retardant polyacrylonitrile copolymer containing the phosphorus structure does not contain halogen elements, so that the problem of secondary pollution of the halogen elements in the combustion process does not exist, the raw materials required for synthesizing the phosphorus flame retardant monomer are low-toxic or non-toxic, and part of the phosphorus flame retardant monomer is industrialized, so that the flame-retardant polyacrylonitrile copolymer is a really good green high polymer material.

2. Because the flame retardant has a flexible group, methyl acrylate or vinyl acetate which is required to be added in the traditional acrylic copolymerization is not required to be added to adjust the flexibility of a molecular chain segment, and the cost is saved.

3. The data in the examples show that the introduction rate of the phosphorus-containing monomer is higher than that of part of the prior art by more than 10%, and the yield is improved by more than 10%, that is to say, the method can greatly improve the introduction rate of the phosphorus-containing monomer and the yield of the phosphorus-containing polyacrylonitrile copolymer in the polymerization process so as to reduce the pressure of subsequent recovery, and is beneficial to the industrialization of products.

By adopting the technical scheme of the invention, the obtained polyacrylonitrile copolymer can obtain high-efficiency flame retardant property, the phosphorus-containing monomer introduction rate and the polymer reaction yield are high, and meanwhile, the synthesis process is simple, the industrialization is easy, and a better technical effect is obtained.

The present invention will be further illustrated by the following examples, but is not limited to these examples.

Detailed Description

It is to be noted that, in the polymers of examples, the mass ratio of the structural units of acrylonitrile and the phosphorus-containing monomer was calculated by elemental analysis.

[ example 1 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 80:20 and accounts for 30 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 70% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 67.7%. After coating, the LOI of the test film is 21.4%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 90.9:9.1, the phosphorus-containing monomer introduction rate is 30.8%.

[ example 2 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the acrylonitrile monomer to the vinyl dimethyl phosphate is 90:10 and accounts for 15 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 80% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 72.1%. After coating, the LOI of the test film is 20.0%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is as follows: 95.0:5.0, and the introduction rate of the phosphorus-containing monomer is 36.1 percent.

[ example 3 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 70:30 and accounts for 40 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 60% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 67.5%. After coating, the LOI of the test film was 25.6%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer was: 85.7:14.3, and the introduction rate of the phosphorus-containing monomer is 32.2 percent.

[ example 4 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the acrylonitrile monomer to the vinyl dimethyl phosphate is 64:36 and accounts for 45 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 55% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 h. The reaction yield was 61.8%. After coating, the LOI of the test film was 28.2%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer was: 83:17, the introduction rate of the phosphorus-containing monomer is 29.2%.

[ example 5 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 60.6%. After coating, the LOI of the test film is 30.5%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 77.4:22.6, and the introduction rate of the phosphorus-containing monomer is 34.2 percent.

[ example 6 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 50:50 and accounts for 60 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 40% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 h. The reaction yield was 58.3%. After coating, the LOI of the test film is 31.6%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is as follows: 71:29, the phosphorus-containing monomer introduction rate is 33.8%.

[ example 7 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.6 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 59.3%. After coating, the LOI of the test film is 29.5%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 80.7:19.3, the phosphorus-containing monomer introduction rate is 28.6%.

[ example 8 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.4 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 58.3%. After coating, the LOI of the test film is 29.3%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 80.6:19.1, the introduction rate of the phosphorus-containing monomer is 27.8 percent.

[ example 9 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the dosage of the initiator accounts for 0.2 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 49.5%. After coating, the LOI of the test film was 28.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer was: 83.0:18.0, and the introduction rate of the phosphorus-containing monomer is 22.3 percent.

[ example 10 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.1 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 45.1%. After coating, the LOI of the test film was 28.4%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer was: 83.9:17.1, the introduction rate of the phosphorus-containing monomer is 19.3%.

[ example 11 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 20:80 and accounts for 70 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 30% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 42.3%. After coating, the LOI of the test film was 33.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer was: 60.0:40.0, the introduction rate of phosphorus-containing monomer is 21.2%.

[ example 12 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 1% of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50% of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 64.5%. After coating, the LOI of the test film is 30.5%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 77.6:22.4, and the introduction rate of the phosphorus-containing monomer is 36.1 percent.

[ example 13 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 5 h. The reaction yield was 36.3%. After coating, the LOI of the test film is 29.6%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 79.8:20.2, the introduction rate of the phosphorus-containing monomer is 18.3 percent.

[ example 14 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 24 h. The reaction yield was 60.6%. After coating, the LOI of the test film is 30.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 76.8:23.2, the phosphorus-containing monomer introduction rate is 35.1%.

[ example 15 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 60 ℃, the stirring is started, and the reaction time is 10 h. The reaction yield was 46.6%. After coating, the LOI of the test film is 30.2%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is as follows: 79.2:20.8, the introduction rate of the phosphorus-containing monomer is 24.2%.

[ example 16 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 80 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 62.6%. After coating, the LOI of the test film is 30.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 77.0:23.0, and the introduction rate of the phosphorus-containing monomer is 36.0 percent.

[ example 17 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent glycol dimethyl ether accounts for 50 percent of the weight of the whole system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 61.2%. After coating, the LOI of the test film is 30.4%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 78.0:22.0, the introduction rate of phosphorus-containing monomer is 33.7%.

[ example 18 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent acetonitrile accounts for 50% of the weight of the whole system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 h. The reaction yield was 63.8%. After coating, the LOI of the test film is 30.0%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is as follows: 78.8:21.2, the phosphorus-containing monomer introduction rate is 33.8%.

[ example 19 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the amount of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent ethanol accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 50.4%. After coating, the LOI of the test film is 29.6%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 79.4:20.6, the phosphorus-containing monomer introduction rate is 26.0%.

[ example 20 ]

Adopting a suspension polymerization method, taking azobisisoheptonitrile as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of acrylonitrile to vinyl dimethyl phosphate accounts for 50 percent of the weight of the whole system, wherein the ratio of acrylonitrile to vinyl dimethyl phosphate is 60: 40; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 60.6%. After coating, the LOI of the test film is 30.5%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 77.6:22.4, and the introduction rate of the phosphorus-containing monomer is 33.9 percent.

[ example 21 ]

Adopting a suspension polymerization method, taking azobisisobutylamidine hydrochloride as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomers, and the ratio of acrylonitrile to vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 46.3%. After coating, the LOI of the test film is 29.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 79.4:20.6, the phosphorus-containing monomer introduction rate is 23.8%.

[ example 22 ]

Adopting a suspension polymerization method, taking dibenzoyl peroxide as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of acrylonitrile monomer to vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 64.6%. After coating, the LOI of the test film is 31.2%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is as follows: 75.4:24.6, the phosphorus-containing monomer introduction rate is 39.7%.

[ example 23 ]

Adopting a suspension polymerization method, taking tert-butyl peroxybenzoate as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the proportion of acrylonitrile and vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 62.6%. After coating, the LOI of the test film is 30.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 76.8:23.2, the phosphorus-containing monomer introduction rate is 36.3%.

[ example 24 ]

Adopting a suspension polymerization method, using dicumyl peroxide as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of acrylonitrile monomer to vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 63.0%. After coating, the LOI of the test film is 30.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 76.7:23.3, the phosphorus-containing monomer introduction rate is 36.7%.

[ example 25 ]

Adopting a suspension polymerization method, using diisopropyl peroxydicarbonate as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the proportion of the acrylonitrile monomer and the vinyl dimethyl phosphate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 47.4%. After coating, the LOI of the test film is 30.6%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer is: 77.4:22.6, and the introduction rate of the phosphorus-containing monomer is 26.8 percent.

[ example 26 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the (dimethoxyphosphono) methacrylate is 60:40 and accounts for 50 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 65.3%. After coating, the LOI of the test film was 28.5%, and the mass ratio of acrylonitrile to (dimethoxyphosphono) methacrylate in the polymer was: 79.8:20.2, the introduction rate of phosphorus-containing monomer is 33.0%.

[ example 27 ]

Adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of the monomer, and the ratio of the monomer acrylonitrile to the dimethyl (acrylamide methyl) phosphonate accounts for 50 percent of the weight of the whole system, wherein the ratio of the monomer acrylonitrile to the dimethyl (acrylamide methyl) phosphonate is 60: 40; the solvent 1, 4-dioxane accounts for 50% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 67.6%. After coating, the LOI of the test film was 28.8%, and the mass ratio of acrylonitrile to vinyl dimethyl phosphate in the polymer was: 80.2:19.8, the phosphorus-containing monomer introduction rate is 33.5%.

[ COMPARATIVE EXAMPLE 1 ]

Carrying out polymerization according to the proportion of conventional polyacrylonitrile fibers but adopting a suspension polymerization method, taking azobisisobutyronitrile as an initiator, wherein the dosage of the initiator accounts for 0.8 percent of the weight of a monomer, and the ratio of the monomer acrylonitrile to the monomer methyl acrylate is 90:9 and accounts for 15 percent of the weight of the whole system; the solvent 1, 4-dioxane accounts for 85% of the total weight of the system, the polymerization temperature is 65 ℃, the stirring is started, and the reaction time is 10 hours. The reaction yield was 78.6%. After coating, the LOI of the test film was 18.6%.

[ COMPARATIVE EXAMPLE 2 ]

Carrying out polymerization according to a conventional polyacrylonitrile fiber method, namely adopting a water-phase precipitation polymerization method, taking potassium persulfate and sodium bisulfite as initiators, wherein the dosage of the initiators accounts for 0.8 percent of the weight of the monomers, and the ratio of the acrylonitrile monomers to the vinyl dimethyl phosphonate accounts for 20 percent of the weight of the whole system at 60: 40; the solvent water accounts for 80% of the weight of the whole system, the pH of the initial system is adjusted to 2-3 by using nitric acid, the polymerization temperature is 65 ℃, stirring is started, and the reaction time is 10 hours. After the reaction, it was found that the polymer did not precipitate from the aqueous phase in the form of powder, but formed a paste-like substance dispersed in the aqueous phase, which caused great troubles in the post-treatment and was not favorable for the production of the product.

[ COMPARATIVE EXAMPLE 3 ]

Carrying out polymerization according to a conventional polyacrylonitrile fiber method, namely adopting a water-phase precipitation polymerization method, taking potassium persulfate and sodium bisulfite as initiators, wherein the dosage of the initiators accounts for 0.8 percent of the weight of the monomers, and the ratio of the acrylonitrile monomers to the vinylphosphonic acid is 70:30 and accounts for 20 percent of the weight of the whole system; the solvent water accounts for 80% of the weight of the whole system, the polymerization temperature is 65 ℃, stirring is started, the pH of the initial system is adjusted to 2-3 by using sodium hydroxide, and the reaction time is 10 hours. The reaction yield was 57.2%, and the mass ratio of acrylonitrile to vinylphosphoric acid in the polymer was: 95.9:4.1, the introduction rate of phosphorus-containing monomer is 7.8%.

Obviously, compared with the comparative example, the polyacrylonitrile copolymer containing phosphate prepared by the method has excellent flame retardant property and industrialization prospect, has great technical advantages, and can be applied to producing environment-friendly flame retardant acrylic fibers.