VDC-an composition and preparation method therefor

Abstract

Disclosed in the present invention are a VDC-AN composition and a preparation method therefor. The composition is prepared from the following components in parts by weight: 5-20 parts of a vinylidene chloride monomer, 5-20 parts of an acrylonitrile monomer, 0.1-1 part of a dyeing monomer, 0.1-0.8 parts of an acrylate monomer, 0.1-1 part of a copolymeric emulsifier, 0.1-0.5 parts of an initiator, and 50-100 parts of deionized water. The preparation method comprises: (1) preparing reaction raw materials for later use; (2) preparing an emulsifier aqueous solution; (3) preparing a polymerization initiator aqueous solution; (4) preparing a residue elimination initiator aqueous solution; (5) seed emulsion polymerization; (6) feeding polymerization; and (7) post-treatment. Fibers prepared by spinning the composition of the present invention have high strength, good dyeing performance and excellent flame retardancy, and exhibit the advantages of a simple process, environmental friendliness, good product performance, etc.

Description

A VDC-AN composition and its preparation method Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a VDC-AN composition and its preparation method. Background Technology

[0002] Acrylonitrile-vinylidene chloride (VDC-AN composition) fiber, also known as modified acrylic fiber, is mainly obtained by polymerizing acrylonitrile (AN), vinylidene chloride (VDC), and dyeing monomers. Compared to polyester fiber, acrylic fiber possesses the softness of natural fibers, excellent water absorption and comfort, good dyeing properties, and superior fire retardant properties, making it highly favored in the high-end fiber market. Therefore, many technical experts in the industry are exploring manufacturing methods for acrylic resin.

[0003] For example, CN104558392A discloses a method for manufacturing highly flame-retardant modified polyacrylonitrile and flame-retardant fibers. This method involves prepolymerizing components A and B separately to obtain a first prepolymer solution and a second prepolymer solution. The first and second prepolymer solutions are then blended or copolymerized in a predetermined ratio to obtain highly flame-retardant modified polyacrylonitrile with a molecular weight not exceeding 80,000. While this invention improves the dyeing, flame-retardant, and processing properties of highly flame-retardant modified acrylonitrile fibers, it uses an organic solvent as the dispersion medium, which requires subsequent separation and purification. This solvent is also prone to ignition during polymerization and operation, and is not environmentally friendly. Furthermore, it requires the synthesis of two polymers followed by mixing, making the process overly cumbersome.

[0004] For example, CN107734988A discloses acrylic fibers for artificial hair, a method for manufacturing the same, and a hair ornament comprising them. This invention relates to an acrylic fiber for artificial hair, which is an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride, and / or vinylidene chloride with a vinyl monomer containing sulfonic acid groups. The acrylic fiber for artificial hair contains 0.1-3% by mass of an organic solvent capable of dissolving the acrylic copolymer relative to its total mass. The acrylic fiber for artificial hair has an average surface roughness of 5900 μm in a region of 40 μm longitudinally and 80 μm transversely on its side surface. 2The following describes the process for producing acrylic fibers for artificial hair. These fibers can be manufactured by wet spinning a spinning solution containing 8-16 parts by weight of water per 100 parts by weight of the acrylic copolymer. The invention proposes an emulsion method for synthesizing AN-VDC resin, using sulfonate as an initiator to effectively solve the problem of phase separation between the dye monomer (hydrophilic) and the main monomers AN and VDC (oleophilic), thus providing a better solution to the dyeing problem of acrylonitrile fibers. However, the use of anionic emulsifiers results in emulsifier residue in the AN-VDC resin after demulsification, increasing the washing process, affecting the continuous operation of the equipment, and increasing costs. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a VDC-AN composition with high strength, good dyeing performance and excellent flame retardant performance, and a method for preparing the same.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a VDC-AN composition, characterized in that it is prepared from the following components in parts by weight:

[0007] Compared with existing technologies, the present invention has the following advantages:

[0008] 1. By optimizing the feed formulation, this invention effectively solves the problem of large differences in the polymerization rates of vinylidene chloride, acrylonitrile, and dyeing monomers. The resulting composition has better fiber uniformity after spinning and processing, and the dyeing effect is more uniform, without the phenomenon of uneven color depth after dyeing.

[0009] 2. By introducing a copolymer emulsifier, this invention ensures the stability of latex ions while its special flexible structure can effectively improve the softness of fibers after spinning. At the same time, its common carboxyl or sulfonic acid groups also have good dyeing properties, achieving better dyeing performance of fibers.

[0010] 3. The fiber obtained by spinning the composition of the present invention has excellent properties. The present invention introduces specific flexible and dyeing groups by introducing a copolymer emulsifier, thereby reducing the amount of flexible monomers and dyeing monomers used, and further improving the fiber properties. The resulting fiber strength can reach more than 2.7 cN / dtex, the limiting oxygen index (LOI) can reach more than 31, and the dyeing rate can reach more than 91%.

[0011] In a preferred embodiment of the present invention, the dyeing monomer is at least one of allyl sulfonic acid, methacrylic acid sulfonic acid, isoprene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and their metal salts and amine salts.

[0012] In a preferred embodiment of the present invention, the acrylate monomer is at least one of methyl acrylate, n-butyl acrylate, and isooctyl acrylate.

[0013] In a preferred embodiment of the present invention, the copolymer emulsifier is at least one of the following: dialkyl sulfosuccinic acid containing double bonds, alkyl alcohol ether sulfuric acid containing double bonds, allyl polyether phosphate, and their metal salts and amine salts.

[0014] As a preferred embodiment of the present invention, the dialkyl sulfonosuccinic acid containing double bonds has the following structural formula:

[0015] Where R1 is C6-C 14 A straight-chain or branched alkane group, where R2 is C6-C. 14 R3 is a straight-chain or branched alkane group, where R3 is an H group or a C1-C3 straight-chain or branched alkane group.

[0016] The dialkyl sulfosuccinic acid containing a double bond group is more preferably at least one of allyl bisdodecyl sulfosuccinic acid, allyl bisoctyl sulfosuccinic acid, and allyl bisdecyl sulfosuccinic acid.

[0017] As a preferred embodiment of the present invention, the alkyl alcohol ether sulfuric acid containing double bonds has the following structural formula:

[0018] Where a ranges from 2 to 10, and b ranges from 2 to 8.

[0019] The alkyl alcohol ether sulfuric acid containing a double bond group is more preferably at least one of allyl dodecyl alcohol ether sulfuric acid and allyl decyl alcohol ether sulfuric acid.

[0020] As a preferred embodiment of the present invention, the allyl polyether phosphate ester has the following structural formula:

[0021] The range of n is 2-12.

[0022] The allyl polyether phosphate ester is more preferably an allyl polyether (n=5) phosphate ester.

[0023] In a preferred embodiment of the present invention, the initiator is at least one of tert-butyl hydroperoxide and sodium thiosulfate.

[0024] The VDC-AN composition of this invention, through optimized formulation, effectively solves the problem of significant differences in the polymerization rates between vinylidene chloride, acrylonitrile, and dyeing monomers, resulting in a VDC-AN composition with excellent copolymer structure. By introducing dyeing monomers and reducing emulsifier usage, this invention effectively avoids the problem of residual auxiliaries after the reaction, reduces washing steps, and enables continuous production. Furthermore, thanks to the excellent flexible groups and carboxylic or sulfonic acid groups of the copolymer emulsifier, the resulting VDC-AN composition produces fibers with superior softness and dyeing properties after spinning. The VDC-AN composition obtained by this invention is particularly suitable for spinning processes and can be widely used in flame-retardant clothing, flame-retardant furniture, and many fire-resistant applications.

[0025] In this invention, the introduction of copolymer emulsifiers ensures the stability of latex ions, while its special flexible structure can also effectively improve the softness of fibers after spinning. At the same time, its common carboxyl or sulfonic acid groups also have good dyeing properties, achieving better dyeing performance of fibers.

[0026] The method for preparing the above-mentioned VDC-AN composition includes the following steps:

[0027] (1) Prepare the reaction raw materials for later use;

[0028] (2) Preparation of emulsifier aqueous solution: Prepare an emulsifier aqueous solution by mixing copolymer emulsifier with 3-10% deionized water for later use;

[0029] (3) Prepare an aqueous solution of polymerization initiator: Prepare an aqueous solution of polymerization initiator by mixing 15-20% initiator with 10-20% deionized water for later use;

[0030] (4) Prepare an aqueous solution of residual initiator: Mix the remaining initiator with 5-10% deionized water to prepare an aqueous solution of residual initiator for later use;

[0031] (5) Seed emulsion polymerization: Add the remaining deionized water, 5-10% vinylidene chloride monomer, 5-10% acrylonitrile monomer, 5-10% dye monomer, 5-10% acrylate monomer, and 5-10% emulsifier aqueous solution to the polymerization kettle. Disperse the emulsion at a stirring speed of 80-150 rpm for 15-35 minutes, raise the temperature to 45-75℃, add 5-10% polymerization initiator aqueous solution to react, and react for 0.5-2.5 h to obtain seed emulsion.

[0032] (6) Additive polymerization: At a temperature of 45-75℃ and a stirring speed of 80-150rpm, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining dye monomer, the remaining acrylate monomer, the remaining emulsifier aqueous solution, and the remaining polymerization initiator aqueous solution are added to the above seed emulsion for reaction. The reaction time is 4-8h to obtain the reaction product.

[0033] (7) Post-treatment: At a temperature of 45-75℃ and a stirring speed of 80-150rpm, add an aqueous solution of a residual initiator to the reaction product obtained in step (6) for reaction. The reaction time is 0.5-1.5h. After the reaction is completed, cool down and discharge the material. The obtained material is demulsified, flashed, and dried to obtain the VDC-AN composition.

[0034] Preferably, the polymerization reactor is evacuated before the seed emulsion polymerization.

[0035] Preferably, the flash evaporation temperature in step (7) is 60-80°C and the pressure is -0.09--0.01 MPa; the drying temperature is 35-70°C.

[0036] 1. The preparation method of the present invention adopts emulsion polymerization process. By optimizing factors affecting the reaction such as polymerization process, reaction temperature and time, feed formulation and feed method, the preparation process is optimized, which effectively solves the problem of large differences in the reactivity ratios of vinylidene chloride and acrylonitrile and dyeing monomers. The resulting composition has better fiber uniformity after spinning and processing, and the dyeing effect is more uniform, without the phenomenon of uneven color depth after dyeing.

[0037] 2. The composition obtained by the method of the present invention does not require a washing process after mechanical demulsification. It can be dried after removing residual additives and moisture by flash evaporation to obtain the VDC-AN composition. Attached Figure Description

[0038] Figure 1 is a SEM image of the resin in Example 4 and Comparative Example 1 of the present invention;

[0039] Figure 2 is a fiber SEM image of Example 6 and Comparative Example 2 of the present invention.

[0040] Wherein, a1 and a2 are the morphologies of the resin state after demulsification in Example 4 at different scales, b1 and b2 are the morphologies of the resin state in Comparative Example 1 at different scales; a3 and a4 are the morphologies of the fiber state after spinning in Example 6 at different scales, and b3 and b4 are the morphologies of the fiber state after spinning in Comparative Example 2 at different scales. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0042] Example 1

[0043] A VDC-AN composition, based on a 1kg portion, has the following raw material formulation:

[0044] Polymerization initiator: tert-butyl hydroperoxide (TBHP) 30g, sodium thiosulfate (SFS) 30g

[0045] Initiator for residue removal: 150g tert-butyl hydroperoxide, 150g styrax bleach, 70kg deionized water

[0046] The preparation method is as follows:

[0047] (1) Prepare emulsifier aqueous solution: Weigh 0.25 kg of allyl bis(dodecyl)sulfosuccinic acid and prepare an emulsifier aqueous solution with 3 kg of deionized water for later use;

[0048] (2) Prepare the polymerization initiator aqueous solution: Weigh 30g of TBHP and prepare a TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 30g of SFS and prepare an SFS aqueous solution with 5Kg of deionized water for later use.

[0049] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 150g of TBHP and prepare an aqueous solution of TBHP with 2Kg of deionized water for later use; Weigh 150g of SFS and prepare an aqueous solution of SFS with 2Kg of deionized water for later use.

[0050] (4) Seed emulsion polymerization: First, put the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095Mpa, and under this vacuum, pump 1Kg vinylidene chloride monomer, 1.5Kg acrylonitrile monomer, 75g sodium allyl sulfonate, 25g methyl acrylate and 10% of the emulsifier aqueous solution prepared in step (1) into the polymerization kettle, and cold disperse at a stirring speed of 100rpm for 20 minutes. Maintain this speed and raise the temperature to 50℃. Then, add 10% of the TBHP aqueous solution prepared in step (2) and 10% of the SFS aqueous solution prepared in step (2) at a uniform speed within 1h to react for 1h to obtain seed emulsion;

[0051] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 50℃ and the stirring speed at 100rpm. Add the remaining emulsifier aqueous solution, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining sodium allyl sulfonate, the remaining methyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (2) to the seed emulsion obtained in step (4) and react. After reacting for 8 hours, the reaction is stopped and the reaction product is obtained.

[0052] (6) Post-processing: Under the condition of maintaining the polymerization reactor temperature at 50℃ and stirring speed at 100rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 30 minutes. After the feeding is completed, the temperature is lowered to 30℃ and the material is discharged. After mechanical demulsification, the obtained material is put into a flash tank for drying. The flash temperature is 60℃ and the flash pressure is -0.07MPa. After the flash is completed, it is put into a fluidized bed for drying at 45℃. Finally, a VDC-AN composition with a molecular weight of 453584 is obtained.

[0053] Example 2

[0054] A VDC-AN composition, based on a 1kg portion, has the following raw material formulation:

[0055] Polymerization initiator: 32g tert-butyl hydroperoxide, 32g sodium iodide

[0056] Residue-removing initiator: 160g tert-butyl hydroperoxide, 160g styrax bleach, 75kg deionized water

[0057] The preparation method is as follows:

[0058] (1) Prepare an emulsifier aqueous solution: Weigh 0.5 kg of allyl dodecyl alcohol ether sodium sulfate and prepare an emulsifier aqueous solution with 3 kg of deionized water for later use;

[0059] (2) Preparation of polymerization initiator aqueous solution: Weigh 32g of TBHP and prepare TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 32g of SFS and prepare SFS aqueous solution with 5Kg of deionized water for later use.

[0060] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 160g of TBHP and prepare an aqueous solution of TBHP with 2Kg of deionized water for later use; Weigh 160g of SFS and prepare an aqueous solution of SFS with 2Kg of deionized water for later use.

[0061] (4) Seed emulsion polymerization: First, put the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095Mpa, and under this vacuum, pump 0.75Kg vinylidene chloride monomer, 0.5Kg acrylonitrile monomer, 25g sodium 2-acrylamide-2-methylpropanesulfonate, 25g n-butyl acrylate and 5% of the emulsifier aqueous solution prepared in step (1) into the polymerization kettle. Cold disperse at 80rpm stirring speed for 25 minutes, maintain this speed and heat up to 55℃, and then uniformly add 5% of the TBHP aqueous solution prepared in step (2) and 5% of the SFS aqueous solution prepared in step (2) within 1h to react for 1.5h to obtain seed emulsion;

[0062] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 55℃ and the stirring speed at 80 rpm. Add the remaining emulsifier aqueous solution, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining sodium 2-acrylamide-2-methylpropanesulfonate, the remaining n-butyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (2) to the seed emulsion obtained in step (4) and react for 4 hours to end the reaction and obtain the reaction product.

[0063] (6) Post-processing: Under the condition of maintaining the polymerization reactor temperature at 55℃ and stirring speed at 80rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 60 minutes. After the feeding is completed, the temperature is reduced to 30℃ and the material is discharged. After mechanical demulsification, the obtained material is put into a flash tank for drying. The flash temperature is 70℃ and the flash pressure is -0.05MPa. After the flash is completed, it is put into a fluidized bed for drying at 50℃. Finally, a VDC-AN composition with a molecular weight of 442486 is obtained.

[0064] Example 3

[0065] A VDC-AN composition, based on a 1kg portion, has the following raw material formulation:

[0066] Polymerization initiator: 35g tert-butyl hydroperoxide, 35g sodium iodide

[0067] Initiator for residue removal: 175g tert-butyl hydroperoxide, 175g styrax bleach, 60kg deionized water

[0068] The preparation method is as follows:

[0069] (1) Prepare emulsifier aqueous solution: Weigh 0.75 kg of allyl polyether (n=5) phosphate ester and prepare emulsifier aqueous solution with 3 kg of deionized water for later use;

[0070] (2) Prepare the polymerization initiator aqueous solution: Weigh 35g of TBHP and prepare TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 35g of SFS and prepare SFS aqueous solution with 5Kg of deionized water for later use.

[0071] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 175g of TBHP and prepare an aqueous solution of TBHP with 2Kg of deionized water for later use; Weigh 175g of SFS and prepare an aqueous solution of SFS with 2Kg of deionized water for later use.

[0072] (4) Seed emulsion polymerization: First, put the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095Mpa, and pump 1Kg vinylidene chloride monomer, 1Kg acrylonitrile monomer, 60g sodium 2-acrylamide-2-methylpropanesulfonate, 12g isooctyl acrylate and 8% of the emulsifier aqueous solution prepared in step (1) into the polymerization kettle under this vacuum. Cold disperse at a stirring speed of 120rpm for 20 minutes, and keep the speed at this speed to raise the temperature to 60℃. Then, add 8% of the TBHP aqueous solution prepared in step (2) and 8% of the SFS aqueous solution prepared in step (2) at a uniform rate within 1h to react for 2h to obtain seed emulsion.

[0073] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 60℃ and the stirring speed at 120rpm. Add the remaining emulsifier aqueous solution, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining sodium 2-acrylamide-2-methylpropanesulfonate, the remaining isooctyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (2) to the seed emulsion obtained in step (4) and react for 6 hours to end the reaction and obtain the reaction product.

[0074] (6) Post-processing: Under the condition of maintaining the polymerization reactor temperature at 60℃ and stirring speed at 120rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 30 minutes. After the feeding is completed, the temperature is lowered to 30℃ and the material is discharged. After mechanical demulsification, the obtained material is put into a flash tank for drying. The flash temperature is 65℃ and the flash pressure is -0.09MPa. After the flash is completed, it is put into a fluidized bed for drying at 45℃. Finally, a VDC-AN composition with a molecular weight of 445689 is obtained.

[0075] Example 4

[0076] A VDC-AN composition, based on a 1kg portion, has the following raw material formulation:

[0077] Polymerization initiator: 32g tert-butyl hydroperoxide, 32g sodium iodide

[0078] Residue-removing initiator: 150g tert-butyl hydroperoxide, 150g styrax bleach, 72kg deionized water

[0079] The preparation method is as follows:

[0080] (1) Prepare an emulsifier aqueous solution: Weigh 0.5 kg of allyl decyl alcohol ether sodium sulfate and prepare an emulsifier aqueous solution with 5 kg of deionized water for later use;

[0081] (2) Preparation of polymerization initiator aqueous solution: Weigh 32g of TBHP and prepare TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 32g of SFS and prepare SFS aqueous solution with 5Kg of deionized water for later use.

[0082] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 150g of TBHP and prepare an aqueous solution of TBHP with 2Kg of deionized water for later use; Weigh 150g of SFS and prepare an aqueous solution of SFS with 2Kg of deionized water for later use.

[0083] (4) Seed emulsion polymerization: First, put the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095Mpa, and under this vacuum, pump 0.9Kg vinylidene chloride monomer, 1.1Kg acrylonitrile monomer, 20g sodium methacrylate, 20g sodium 2-acrylamide-2-methylpropanesulfonate, 40g methyl acrylate and 8% of the emulsifier aqueous solution prepared in step (1) into the polymerization kettle, and cold disperse at a stirring speed of 100rpm for 20 minutes, and maintain this speed to raise the temperature to 55℃, and then uniformly add 8% of the TBHP aqueous solution prepared in step (2) and 8% of the SFS aqueous solution prepared in step (2) within 1.5h to react for 1.5h to obtain seed emulsion;

[0084] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 55℃ and the stirring speed at 100 rpm. Add the remaining emulsifier aqueous solution, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining sodium methacrylate, the remaining sodium 2-acrylamide-2-methylpropanesulfonate, the remaining methyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (2) to the seed emulsion obtained in step (4) and react. After reacting for 6 hours, the reaction is stopped and the reaction product is obtained.

[0085] (6) Post-processing: Under the condition of maintaining the polymerization reactor temperature at 55℃ and stirring speed at 100rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 30 minutes. After the feeding is completed, the temperature is lowered to 30℃ and the material is discharged. After mechanical demulsification, the obtained material is put into a flash tank for drying. The flash temperature is 70℃ and the flash pressure is -0.05MPa. After the flash is completed, it is put into a fluidized bed for drying at 50℃, and finally the VDC-AN composition with a molecular weight of 450257 is obtained.

[0086] Example 5

[0087] A VDC-AN composition, based on a 1kg portion, has the following raw material formulation:

[0088] Polymerization initiator: 34g tert-butyl hydroperoxide, 34g sodium iodide

[0089] Residue-removing initiator: 170g tert-butyl hydroperoxide, 170g styrax bleach, 65kg deionized water

[0090] The preparation method is as follows:

[0091] (1) Prepare an emulsifier aqueous solution: Weigh 0.75 kg of allyl bisoctyl sulfosuccinic acid and prepare an emulsifier aqueous solution with 3 kg of deionized water for later use;

[0092] (2) Preparation of polymerization initiator aqueous solution: Weigh 34g of TBHP and prepare TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 34g of SFS and prepare SFS aqueous solution with 5Kg of deionized water for later use.

[0093] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 170g of TBHP and prepare an aqueous solution of TBHP with 2Kg of deionized water for later use; Weigh 170g of SFS and prepare an aqueous solution of SFS with 2Kg of deionized water for later use.

[0094] (4) Seed emulsion polymerization: First, put the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095Mpa, and under this vacuum, pump 1.375Kg vinylidene chloride monomer, 1.125Kg acrylonitrile monomer, 25g isoprene sulfonic acid, 25g sodium allyl sulfonate, 25g methyl acrylate and 10% of the emulsifier aqueous solution prepared in step (1) into the polymerization kettle, and cold disperse at a stirring speed of 150rpm for 15 minutes, and maintain this speed to raise the temperature to 75℃, and then uniformly add 10% of the TBHP aqueous solution prepared in step (2) and 10% of the SFS aqueous solution prepared in step (2) within 1h to react for 1h to obtain seed emulsion;

[0095] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 75℃ and the stirring speed at 150rpm. Add the remaining emulsifier aqueous solution, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining isoprene sulfonic acid, the remaining sodium allyl sulfonate, the remaining methyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (2) to the seed emulsion obtained in step (4) and react. After reacting for 4 hours, the reaction is stopped and the reaction product is obtained.

[0096] (6) Post-processing: Under the condition of maintaining the polymerization reactor temperature at 75℃ and stirring speed at 150rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 90 minutes. After the feeding is completed, the temperature is reduced to 30℃ and the material is discharged. After mechanical demulsification, the obtained material is put into a flash tank for drying. The flash temperature is 70℃ and the flash pressure is -0.05MPa. After the flash is completed, it is put into a fluidized bed for drying at 50℃. Finally, a VDC-AN composition with a molecular weight of 460273 is obtained.

[0097] Example 6

[0098] A VDC-AN composition, based on a 1kg portion, has the following raw material formulation:

[0099] Polymerization initiator: 30g tert-butyl hydroperoxide, 30g sodium iodide

[0100] Initiator for residue removal: 150g tert-butyl hydroperoxide, 150g styrax bleach, 70kg deionized water

[0101] The preparation method is as follows:

[0102] (1) Prepare an emulsifier aqueous solution: Weigh 0.25 kg of sodium allyl bisdecyl sulfosuccinate and 0.25 kg of sodium allyl dodecyl alcohol ether sulfate, and prepare an emulsifier aqueous solution with 3 kg of deionized water for later use;

[0103] (2) Prepare the polymerization initiator aqueous solution: Weigh 30g of TBHP and prepare a TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 30g of SFS and prepare an SFS aqueous solution with 5Kg of deionized water for later use.

[0104] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 150g of TBHP and prepare an aqueous solution of TBHP with 2Kg of deionized water for later use; Weigh 150g of SFS and prepare an aqueous solution of SFS with 2Kg of deionized water for later use.

[0105] (4) Seed emulsion polymerization: First, put the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095Mpa, and under this vacuum, pump 0.9Kg vinylidene chloride monomer, 1.1Kg acrylonitrile monomer, 20g sodium allyl sulfonate, 20g n-butyl acrylate and 8% of the emulsifier aqueous solution prepared in step (1) into the polymerization kettle, and cold disperse at a stirring speed of 100rpm for 25 minutes. Maintain this speed and raise the temperature to 50℃. Then, add 8% of the TBHP aqueous solution prepared in step (2) and 8% of the SFS aqueous solution prepared in step (2) at a uniform rate within 1h to react for 1.5h to obtain seed emulsion;

[0106] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 50°C and the stirring speed at 100 rpm. Add the remaining emulsifier aqueous solution, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining sodium allyl sulfonate, the remaining n-butyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (3) to the seed emulsion obtained in step (4) and react for 6 hours to end the reaction and obtain the reaction product.

[0107] (6) Post-processing: Under the condition of maintaining the polymerization reactor temperature at 50℃ and stirring speed at 100rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 45 minutes. After the feeding is completed, the temperature is reduced to 30℃ and the material is discharged. After mechanical demulsification, the obtained material is put into a flash tank for drying. The flash temperature is 70℃ and the flash pressure is -0.05MPa. After the flash is completed, it is put into a fluidized bed for drying at 50℃. Finally, a VDC-AN composition with a molecular weight of 430846 is obtained. The properties are shown in Table 1.

[0108] Comparative Example 1

[0109] A mixture of modified polyacrylonitrile prepared according to the method described in Example 1 of CN104558392A.

[0110] Comparative Example 2

[0111] Acrylic copolymer latex prepared according to the method described in Example 1 of CN107734988A.

[0112] Performance testing

[0113] The compositions obtained in Examples 1-6 and Comparative Examples 1-2 were used to prepare spun fibers. The preparation process is as follows:

[0114] The composition was dissolved in dimethyl sulfoxide to prepare a resin solution with a resin concentration of 23.0 wt% (wt%, mass percentage concentration) and a water concentration of 2.0 wt%. This spinning solution was then extruded through a spinning nozzle into a coagulation bath of a 65% (w / w) dimethyl sulfoxide aqueous solution at 20°C, where it solidified and became fiberized, followed by stretching and washing. The washed, once-stretched yarn was then impregnated in an oil bath containing a mixture of oil and dimethyl sulfoxide. Finally, after drying at 120°C and stretching relaxation treatment, VDC-AN fibers were obtained. The properties are shown in the table below, where:

[0115] Fiber strength testing: Performed according to the methods specified in GB / T 14337-2022 "Test Method for Tensile Properties of Chemical Fibers (Short Fibers)";

[0116] Color uptake rate: Performed according to the method specified in FZ / T 50024-2014 "Test Method for Color Uptake Rate of Acrylic Fiber";

[0117] Limiting oxygen index (LOI) test: Performed according to the method specified in FZ / T 50029-2015 "Test method for flame retardant properties of synthetic fiber raw material chips".

Claims

1. A VDC-AN composition, characterized in that, It is prepared from the following components in parts by weight:

2. The VDC-AN composition according to claim 1, characterized in that, The dyeing monomers are at least one of allyl sulfonic acid, methylpropene sulfonic acid, isoprene sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, and their metal salts and amine salts.

3. The VDC-AN composition according to claim 1, characterized in that, The acrylate monomers mentioned are at least one of methyl acrylate, n-butyl acrylate, and isooctyl acrylate.

4. The VDC-AN composition according to claim 1, characterized in that, The copolymer emulsifier is at least one of the following: dialkyl sulfosuccinic acid containing double bonds, alkyl alcohol ether sulfuric acid containing double bonds, allyl polyether phosphate, and their metal salts and amine salts.

5. The VDC-AN composition according to claim 4, characterized in that, The structural formula of the dialkyl sulfonosuccinic acid containing double bonds is as follows: Where R1 is C6-C 14 A straight-chain or branched alkane group, where R2 is C6-C. 14 R3 is a straight-chain or branched alkane group, where R3 is an H group or a C1-C3 straight-chain or branched alkane group.

6. The VDC-AN composition according to claim 5, characterized in that, The dialkyl sulfosuccinic acid containing a double bond group is at least one of allyl bisdodecyl sulfosuccinic acid, allyl bisoctyl sulfosuccinic acid, and allyl bisdecyl sulfosuccinic acid.

7. The VDC-AN composition according to claim 4, characterized in that, The structural formula of the alkyl alcohol ether sulfuric acid containing double bonds is as follows: Where a ranges from 2 to 10, and b ranges from 2 to 8.

8. The VDC-AN composition according to claim 7, characterized in that, The alkyl alcohol ether sulfuric acid containing double bonds is at least one of allyl dodecyl alcohol ether sulfuric acid and allyl decyl alcohol ether sulfuric acid.

9. The VDC-AN composition according to claim 4, characterized in that, The structural formula of the allyl polyether phosphate is as follows: The range of n is 2-12.

10. The method for preparing the VDC-AN composition according to claim 1, characterized in that, The initiator is at least one of tert-butyl hydroperoxide and sodium thiosulfate.

11. A method for preparing the VDC-AN composition according to any one of claims 1 to 10, characterized in that, Includes the following steps: (1) Prepare the reaction raw materials for later use; (2) Preparation of emulsifier aqueous solution: Prepare an emulsifier aqueous solution by mixing copolymer emulsifier with 3-10% deionized water for later use; (3) Prepare an aqueous solution of polymerization initiator: Prepare an aqueous solution of polymerization initiator by mixing 15-20% initiator with 10-20% deionized water for later use; (4) Prepare an aqueous solution of residual initiator: Mix the remaining initiator with 5-10% deionized water to prepare an aqueous solution of residual initiator for later use; (5) Seed emulsion polymerization: Add the remaining deionized water, 5-10% vinylidene chloride monomer, 5-10% acrylonitrile monomer, 5-10% dye monomer, 5-10% acrylate monomer, and 5-10% emulsifier aqueous solution to the polymerization kettle. Disperse the emulsion at a stirring speed of 80-150 rpm for 15-35 minutes, raise the temperature to 45-75℃, add 5-10% polymerization initiator aqueous solution to react, and react for 0.5-2.5 h to obtain seed emulsion. (6) Additive polymerization: At a temperature of 45-75℃ and a stirring speed of 80-150rpm, the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining dye monomer, the remaining acrylate monomer, the remaining emulsifier aqueous solution, and the remaining polymerization initiator aqueous solution are added to the above seed emulsion for reaction. The reaction time is 4-8h to obtain the reaction product. (7) Post-treatment: At a temperature of 45-75℃ and a stirring speed of 80-150rpm, add an aqueous solution of a residual initiator to the reaction product obtained in step (6) for reaction. The reaction time is 0.5-1.5h. After the reaction is completed, cool down and discharge the material. The obtained material is demulsified, flashed, and dried to obtain the VDC-AN composition.

12. The method for preparing the VDC-AN composition according to claim 11, characterized in that, The polymerization reactor is evacuated before the seed emulsion polymerization.

13. The method for preparing the VDC-AN composition according to claim 11, characterized in that, The flash evaporation temperature in step (7) is 60-80℃ and the pressure is -0.09--0.01 MPa; the drying temperature is 35-70℃.

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