CN101608348B - Flame retardant cellulose fiber and preparation method thereof - Google Patents

Abstract

The invention discloses a flame-retardant cellulose fiber and a preparation method thereof. The mass ratio of the fiber is: flame retardant: cellulose = 10-25:100, and the flame retardant is a new phosphorus-based flame retardant. The average particle size is less than 1 μm; the cellulose is wood pulp or cotton pulp with a degree of polymerization of 400-1000, and the content of α-cellulose is more than or equal to 90%. The preparation method of the fiber is composed according to the mass ratio of the fiber, including the following processes: 1. Prepare a flame-retardant spinning solution; according to the mass ratio, the flame retardant is first added to the ionic liquid at normal temperature, and mechanically stirred The flame retardant is uniformly dispersed in the ionic liquid, and then the cellulose is added to the ionic liquid to fully dissolve, and the dissolution temperature is 70-110 ° C to prepare a flame retardant spinning solution; the mass of the cellulose and the ionic liquid The ratio is 5-35:95-65; 2. Prepare the flame-resistant cellulose fiber; carry out according to the conventional spinning process to obtain the flame-resistant cellulose fiber.

Description

A kind of flame-retardant cellulose fiber and preparation method thereof

technical field

The invention relates to flame-retardant fiber technology, in particular to a flame-retardant cellulose fiber using ionic liquid as a solvent and a preparation method thereof.

Background technique

The fire caused by the burning of fiber products has become one of the major disasters in modern society, which seriously threatens the safety of people's lives and properties. The results of the investigation of fatal accidents caused by fire show that fires caused by interior decorations and textiles occupy the first place. At the same time, it was found that the harmful gas released by combustible textiles is much more harmful to the human body than non-combustible textiles. Therefore, the production of flame-retardant textiles to prevent fires has become a social problem that cannot be ignored, and has attracted more and more attention. At present, many countries in the world have put forward specific requirements or restrictions on the combustion performance of fibers and their products according to the different uses of textiles, and have formulated corresponding regulations. It stipulates that curtains, curtains, clothing and textiles for the elderly, children, and disabled people in theaters, hospitals, hotels and other public places must meet certain flame-retardant standards.

Cellulose fibers have a long history in man-made fibers and are widely used. Because of its wide source of raw materials, excellent hygroscopicity, breathability, comfortable clothing, good dyeability, etc., it occupies a stable position in the production and application of man-made fibers. However, ordinary cellulose fibers are easy to catch fire and have poor flame retardancy, which cannot meet the requirements of social development and application, thus limiting its application range.

In foreign countries, the research on flame-retardant cellulose fibers is mainly carried out through the viscose method. US Patent No. 3,266,918 adds a flame retardant such as tri-2,3-dibromopropyl phosphoric acid to viscose, and then prepares flame-retardant cellulose fibers by viscose spinning. In this method, when the flame retardant is added to the viscose spinning solution, the chemical activity of the flame retardant and the acidity of the viscose easily cause the degradation of the flame retardant and lose the flame retardancy; U.S. Patent No. 4,063,883 firstly A flame retardant is added to the viscose spinning solution, spun into fibers, and another flame retardant is polymerized on the surface of the fibers, but a catalyst must be used; US Patent No. 4,981,515 is to add flame retardants and activated carbon into the viscose collagen solution, which is then spun into cellulose fibers.

Some domestic patent applications for flame-retardant cellulose fibers have also been proposed, such as CN1098149A, CN101387013A and CN101215726A. CN1098149A document discloses a kind of cellulose polysilicate fiber, is about to add silicate in a certain proportion to viscose collagen solution to make spinning solution, after spinning into fiber, it will be filled with metal (ammonia or ethylenediamine) complex The compound solution is blocked for 5-120 minutes to form cellulose polysilicate fibers. The method is based on the viscose method, and the process is complicated. Document CN101387013A discloses a method of adding a nitrogen-silicon flame retardant to viscose spinning liquid by adopting viscose technology. In order to improve the uniformity of spinning liquid, a dispersing agent needs to be added for treatment. Document CN101215726A reports a method for producing flame-retardant viscose fiber. The method is to uniformly mix pyrophosphate flame retardant particles, nonionic surfactants, dispersants and solvent water to make a flame retardant emulsion, then add it to the filtered viscose, and spin it into a flame retardant fiber vegan fiber. In order to improve the uniformity of dispersion, the method uses nonionic surfactants, dispersants, etc., and the production process is more complicated, and the production cost is increased. The above-mentioned cellulose fibers are all made of viscose fibers, mainly prepared by a blending method. Because it is viscose fiber, the viscose process is adopted, which determines that the entire production process of the flame retardant fiber cannot meet the requirements of energy saving and environmental protection. It is necessary to add dispersants, emulsifiers, etc. to improve the dispersibility and compatibility of flame retardants in the stock solution, and the preparation of the above-mentioned flame-retardant cellulose fiber spinning solution needs to be carried out in two steps, that is, the viscose solution is first prepared , and then add additives such as flame retardant and dispersant, after uniform dispersion, and then spin to prepare flame-retardant cellulose fiber, the process is long, the efficiency is low, and the addition of flame retardant is large, which not only increases the production cost of the product, Reduced the mechanical properties of the product fiber again.

Contents of the invention

Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a flame-retardant cellulose fiber and a preparation method thereof. The fiber does not contain a halogen component flame retardant, the product is safe, and has little damage to the strength, and is suitable for subsequent fiber processing; the preparation method adopts a one-step preparation process, the spinning process is simple, the addition of flame retardant is small, and no need to add Additives such as dispersant and emulsifier have no environmental pollution and meet the requirements of modern green production.

The technical solution of the present invention to solve the technical problem of the flame retardant fiber is: design a kind of flame retardant cellulose fiber, the mass ratio of the fiber is composed of: flame retardant: cellulose=10～25:100, the flame retardant The agent is 2,2'-oxobis(5,5-dimethyl-1,3,2-dioxaphosphorane-2,2'-disulfide), 1,2-bis(2-oxo -5,5-Dimethyl-1,3,2-dioxaphosphorin-2-amino)ethane or N,N'-bis(2-thio-5,5-dimethyl-1 , 3,2-dioxaphosphorinyl)ethylenediamine, the average particle size is less than 1um; the cellulose is wood pulp or cotton pulp with a polymerization degree of 400-1000, and the α-cellulose content is ≥90%.

The technical solution of the present invention to solve the technical problem of the preparation method is: to design a preparation method of flame-retardant cellulose fibers, the preparation method is composed according to the mass ratio of the flame-retardant cellulose fibers of the present invention, including the following processes:

1. Prepare the flame retardant spinning solution; according to the mass ratio of the flame retardant to cellulose, the flame retardant is first added to the ionic liquid at room temperature, and the flame retardant is evenly dispersed in the ionic liquid under mechanical stirring, Then add cellulose into the ionic liquid to fully dissolve, the dissolution temperature is 70-110°C, and prepare a flame-retardant spinning solution;

The ionic liquid is composed of a cation and an anion; the cation is a substituent-containing alkyl quaternary ammonium ion, an alkyl quaternary phosphorus ion, an alkyl imidazolium ion or an alkyl pyridinium ion, wherein the substituent is hydrogen, C One or more of ₁ -C ₆ alkyl, vinyl, propenyl, butenyl, hydroxyethyl, hydroxypropyl and alkoxy; the anions are halide ions, BF ₄ ^- , PF ₄ ^- , SCN ^- , CN ^- , OCN ^- , CNO ^- , CF ₃ SO ₃ ^- , CFCOO ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₂ N ^- or (CF ₃ SO ₂ ) ₂ Cl ^- ;

The mass ratio of the cellulose to the ionic liquid is 5-35:95-65;

2. Preparation of flame-retardant cellulose fibers; the conventional spinning process is used to obtain the flame-retardant cellulose fibers.

Compared with prior art, the present invention has following characteristics:

1. The flame retardant cellulose fiber of the present invention does not contain a halogen component flame retardant, the product is safe to use, and has little damage to the strength, and is suitable for subsequent fiber processing;

2. The preparation method of the present invention uses an appropriate ionic liquid as a cellulose solvent. On the one hand, the amount of flame retardant added is small; Good dispersant effect, simplified process, reduced cost, convenient operation, etc.;

3. The preparation method of the present invention adopts a one-step preparation process. Compared with the traditional viscose method, the process is significantly shortened, the spinning process is simple, the energy consumption is low, the operation cost is low, and it is non-polluting, which is conducive to environmental protection and meets the requirements of green production.

Detailed ways

The present invention is further set forth below in conjunction with embodiment.

The mass ratio composition of the flame-retardant cellulose fiber (abbreviated as fiber) designed by the present invention is: flame retardant: cellulose = 10-25:100.

Because the traditional halogen-containing flame retardants are easy to cause environmental pollution during the flame-retardant process, they have been banned in many countries, while non-halogen flame retardants containing phosphorus, sulfur and nitrogen have better flame-retardant effects due to their synergistic flame-retardant effects. It has good flame retardant effect and will not cause environmental pollution. It is a good flame retardant for cellulose. The flame retardant described in the present invention selects novel phosphorus-based flame retardants as flame retardants, mainly 2,2'-oxobis(5,5-dimethyl-1,3,2-dioxaphosphine- 2,2'-disulfide) (DDPS), 1,2-bis(2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinine-2-amino)ethyl alkane (DDPN) or N,N'-di(2-thio-5,5-dimethyl-1,3,2-dioxaphosphorinyl)ethylenediamine (DDPSN). The average particle size of the flame retardant needs to be ground into particles smaller than 1um.

The cellulose fiber in the present invention refers to the regenerated cellulose fiber prepared from cotton pulp and wood pulp, excluding natural cellulose fibers such as cotton fiber and hemp fiber. The cellulose described in the examples is wood pulp or cotton pulp with a degree of polymerization (DP) of 400-1000, and the content of α-cellulose is more than or equal to 90%.

The present invention simultaneously designs the preparation method (preparation method for short) of described flame-retardant cellulose fiber, and this preparation method comprises the following processes according to the mass ratio composition of flame-retardant cellulose fiber described in the present invention:

1. Prepare flame retardant spinning solution; according to the mass ratio of flame retardant of the present invention to cellulose, first flame retardant is added in the ionic liquid at normal temperature, and the flame retardant is dispersed in the ionic liquid under mechanical stirring uniform, then add cellulose into the ionic liquid to fully dissolve, the dissolution temperature is 70-110°C, and prepare a flame-retardant spinning solution; the mass ratio of the flame retardant to cellulose is 10-25:100; The mass ratio of the cellulose to the ionic liquid is 5-35:95-65.

The ionic liquid is composed of cations and anions; the cations are alkyl quaternary ammonium ions, alkyl quaternary phosphonium ions, alkyl imidazolium ions or alkyl pyridinium ions. The structural formulas of each ion are as follows:

Wherein, R ₁ to R ₆ are one or more of hydrogen, alkyl, vinyl, propenyl, butenyl, hydroxyethyl, hydroxypropyl and alkoxy; R ₁ to R ₆ are the same or different ;

The anions are halogen ions, BF ₄ ^- , PF ₄ ^- , SCN ^- , CN ^- , OCN ^- , CNO ^- , CF ₃ SO ₃ ^- , CFCOO ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₂ N ^- Or one of (CF ₃ SO ₂ ) ₂ Cl ^- .

The flame-retardant spinning solution described in the preparation method of the present invention refers to the spinning (raw) solution prepared by directly dissolving the cellulose in an appropriate ionic liquid containing the flame retardant. The flame retardant spinning solution preparation process constitutes the core content of the fiber one-step preparation process of the present invention.

Studies have shown that ionic liquid 1-allyl-3-methylimidazole chloride (AMIMCI) (see macromolecules, Macromolecules, 2005, 38:8272-8277), 1-butyl-3-methylimidazole chloride ( BMIMCI), 1-ethyl-3-methylimidazole chloride (EMIMCI) and 1-ethyl-3-methylimidazole acetate (EMIMAc) (all see cellulose, Cellulose, 2008, 15:59-66) have Excellent performance in dissolving cellulose, and the cellulose solutions prepared from these ionic liquids have good spinnability. These ionic liquids have many unique properties, such as large liquid temperature range, wide dissolution range, extremely low vapor pressure, and good thermal stability, which make them a good chemical reaction medium. The flame retardants DDPS, DDPN and DDPSN can be easily dispersed uniformly in the ionic liquid, so the fiber preparation process of the present invention does not need to add additives such as dispersants and emulsifiers like conventional methods, which simplifies the process and reduces production cost. The preferred ionic liquid of the preparation method of the present invention is chlorinated 1-allyl-3-methylimidazole (AMIMCI), chlorinated 1-butyl-3-methylimidazole (BMIMCI), chlorinated 1-ethyl-3 - one of methylimidazole (EMIMCI) or 1-ethyl-3-methylimidazole acetate (EMIMAc).

2. Preparation of flame-retardant cellulose fibers; the flame-retardant spinning solution is carried out according to a conventional spinning process to obtain the flame-retardant cellulose fibers. The conventional spinning process includes wet method or dry-wet method, including process steps such as defoaming, filtering, metering, spinning, coagulation, drawing, washing and drying. The coagulation bath is water or an ionic liquid aqueous solution with a mass concentration of 0-50%, and the coagulation bath temperature is 0-90°C.

What is not mentioned in the present invention is applicable to the prior art.

Specific examples of the present invention are given below. The significance of these specific examples is to illustrate the implementation method of the present invention, but not to limit the scope of the claims of the present invention.

Example 1

Add 0.5g of the flame retardant DDPSN that is crushed into an average particle size of less than 1um into 95g of AMIMCI ionic liquid at room temperature, stir evenly, and then add the crushed (opened fibers that are crushed into 1mm×1mm or less) fibers into the ionic liquid Vegetarian wood pulp (polymerization degree DP=592, α-cellulose content 92%) 5g, dissolving temperature is 70 ℃, mechanically stirs until completely dissolving, promptly prepares flame-retardant spinning solution;

The spinning solution is degassed, filtered, metered, spinned, coagulated (the coagulation bath is water, and the temperature of the coagulation bath is 20°C), drawing, washing, drying and other conventional wet process steps to obtain the fiber.

After testing, the dry breaking strength of the fiber obtained in this example is 1.97cN/dtex, and the limiting oxygen index (LOI) is 25.

Example 2

Add 0.5 g of the flame retardant DDPSN that is crushed into a particle size of less than 1 μm into 95 g of AMIMCI ionic liquid at room temperature, stir evenly, then add 5 g of crushed cellulose cotton pulp (DP=800, α-cellulose content 95%), The dissolution temperature is 70°C, mechanically stirred until completely dissolved, and the flame-retardant spinning solution is obtained; the spinning solution is degassed and then spun by dry and wet methods, the spinning air gap is 10cm, and the coagulation bath is 50% ionic liquid aqueous solution. The temperature of the coagulation bath was 20°C. After drawing, washing, drying and other steps, the fiber can be obtained. The rest are the same as embodiment 1.

After testing, the dry breaking strength of the fiber obtained in this example is 2.35 cN/dtex, and the limiting oxygen index (LOI) is 26.

Example 3

Add 1g of the flame retardant DDPSN that is crushed into a particle size of less than 1um into 57.5g of AMIMCI ionic liquid at room temperature, stir evenly, then add 5g of crushed cellulose wood pulp (DP=700, α-cellulose content 93%), dissolve The temperature is 90°C, mechanically stirred until it is completely dissolved, and the flame-retardant spinning solution is obtained; the spinning solution is degassed and then spun by dry-wet method. The spinning air gap is 10 cm, the coagulation bath is water, and the temperature of the coagulation bath is 50° C. The fibers are obtained through drawing, washing, drying and other steps. The rest are the same as embodiment 1.

After testing, the dry breaking strength of the fiber obtained in this example is 2.73cN/dtex, and the limiting oxygen index (LOI) is 32.

Example 4

Add 2 g of the flame retardant DDPS crushed into a particle size of less than 1 um into 40 g of EMIMAc ionic liquid at room temperature, stir evenly, then add 10 g of crushed cellulose wood pulp (DP=400, α-cellulose content 96%), dissolve at The temperature is 90°C, mechanically stirred until it is completely dissolved, and the flame-retardant spinning solution is obtained; the spinning solution is degassed and then spun by dry-wet method. The spinning air gap is 10 cm, the coagulation bath is water, and the temperature of the coagulation bath is 50° C. The fibers are obtained through drawing, washing, drying and other steps. The rest are the same as embodiment 1.

After testing, the dry breaking strength of the fiber obtained in this example is 3.27cN/dtex, and the limiting oxygen index (LOI) is 30.

Example 5

Add 2g of the flame retardant DDPS crushed into a particle size of less than 1um into 90g of BMIMCI ionic liquid at room temperature, stir evenly, then add 10g of crushed cellulose wood pulp (DP=1000, α-cellulose content 95%), dissolve The temperature is 110°C, and mechanically stirred until it is completely dissolved to obtain a flame-retardant spinning solution; the spinning solution is degassed and then spun by dry-wet method. The spinning air gap is 10 cm, the coagulation bath is water, and the temperature of the coagulation bath is 90°C. The fibers are obtained through drawing, washing, drying and other steps. The rest are the same as embodiment 1.

After testing, the dry breaking strength of the fiber obtained in this example is 2.89cN/dtex, and the limiting oxygen index (LOI) is 30.

Example 6

Add 2.5g of the flame retardant DDPN crushed to a particle size of less than 1um into 90g of EMIMCI ionic liquid at room temperature, stir evenly, and then add 10g of crushed cellulose wood pulp (DP=592, α-cellulose content 92%) , the dissolution temperature is 110°C, and mechanically stirred until it is completely dissolved to obtain a flame-retardant spinning solution; the spinning solution is degassed and then spun by a dry-wet method. The spinning air gap is 10 cm, the coagulation bath is water, and the temperature of the coagulation bath is 90°C. The fibers are obtained through drawing, washing, drying and other steps. The rest are the same as embodiment 1.

After testing, the dry breaking strength of the fiber obtained in this example is 2.55 cN/dtex, and the limiting oxygen index (LOI) is 33.

Claims (3)

1. a kind of flame-retardant cellulose fiber, it is characterized in that the mass ratio of this fiber is formed into: flame retardant: cellulose=10～25: 100, and described flame retardant is 2,2 '-oxobis( 5,5-Dimethyl-1,3,2-dioxaphosphorane-2,2'-disulfide), 1,2-bis(2-oxo-5,5-dimethyl-1, 3,2-Dioxaphosphorin-2-amino)ethane or N,N'-bis(2-thio-5,5-dimethyl-1,3,2-dioxaphosphorinyl ) ethylenediamine, the average particle size is less than 1um; the cellulose is wood pulp or cotton pulp with a polymerization degree of 400-1000, and the α-cellulose content is ≥90%. 2. a preparation method of the flame-retardant cellulose fiber described in claim 1, the preparation method comprising the following techniques: (1). Prepare flame retardant spinning solution; according to the mass ratio of flame retardant to cellulose, first add the flame retardant to the ionic liquid at room temperature, and disperse the flame retardant in the ionic liquid under mechanical stirring Uniform, then add cellulose into the ionic liquid to fully dissolve, the dissolution temperature is 70-110°C, and prepare a flame-retardant spinning solution; The ionic liquid is composed of a cation and an anion; the cation is a substituent-containing alkyl quaternary ammonium ion, an alkyl quaternary phosphorus ion, an alkyl imidazolium ion or an alkyl pyridinium ion, wherein the substituent is hydrogen, C One or more of ₁ -C ₆ alkyl, vinyl, propenyl, butenyl, hydroxyethyl, hydroxypropyl and alkoxy; the anions are halide ions, BF ₄ ^- , PF ₄ ^- , SCN ^- , CN ^- , OCN ^- , CNO ^- , CF ₃ SO ₃ ^- , CFCOO ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₂ N ^- or (CF ₃ SO ₂ ) ₂ Cl ^- ; The mass ratio of the cellulose to the ionic liquid is 5-35:95-65; (2). Preparation of flame-retardant cellulose fibers; the conventional spinning process is used to obtain the flame-retardant cellulose fibers. 3. according to the preparation method of the described flame-retardant cellulose fiber of claim 2, it is characterized in that described ionic liquid is chlorinated 1-allyl-3-methylimidazole, chlorinated 1-butyl-3-methylimidazole imidazole, 1-ethyl-3-methylimidazole chloride or 1-ethyl-3-methylimidazole acetate.