A process for the preparation of a vdc-an composition

Abstract

The application discloses a preparation method of VDC-AN combination, comprising the following steps: (1) preparing reaction raw materials; (2) preparing an emulsifier aqueous solution; (3) preparing a polymerization initiator aqueous solution; (4) preparing a residual-removing initiator aqueous solution; (5) seed emulsion polymerization; (6) feeding polymerization; and (7) post-treatment. The application has the advantages of simple process, green environmental protection, good product performance and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a method for preparing a VDC-AN composition. 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 to 3% by mass of an organic solvent capable of dissolving the acrylic copolymer relative to the total mass of the acrylic fiber. 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 the fiber side. 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 method for preparing a VDC-AN composition that is simple in process, environmentally friendly, and has good product performance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing a VDC-AN composition, comprising the following steps:

[0007] (1) Prepare reaction raw materials for later use.

[0008] The composition of the reactants, by weight parts, is as follows:

[0009]

[0010] (2) Preparation of emulsifier aqueous solution: Prepare an emulsifier aqueous solution by mixing copolymer emulsifier with 3-10% deionized water for later use;

[0011] (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;

[0012] (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;

[0013] (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.

[0014] (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.

[0015] (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.

[0016] In a preferred embodiment of the present invention, the polymerization reactor is evacuated before the seed emulsion polymerization.

[0017] 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.

[0018] In a preferred embodiment of the present invention, the acrylate monomer is at least one of methyl acrylate, n-butyl acrylate, and isooctyl acrylate.

[0019] 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.

[0020] As a preferred embodiment of the present invention, the dialkyl sulfonosuccinic acid containing double bonds has the following structural formula:

[0021]

[0022] Where R1 is C6~C 14 A straight-chain or branched alkane group, where R2 is C6 to C6. 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.

[0023] 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.

[0024] As a preferred embodiment of the present invention, the alkyl alcohol ether sulfuric acid containing double bonds has the following structural formula:

[0025]

[0026] Where a ranges from 2 to 10, and b ranges from 2 to 8.

[0027] 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.

[0028] As a preferred embodiment of the present invention, the allyl polyether phosphate ester has the following structural formula:

[0029]

[0030] The value of n ranges from 2 to 12.

[0031] The allyl polyether phosphate ester is more preferably an allyl polyether (n=5) phosphate ester.

[0032] In a preferred embodiment of the present invention, the initiator is at least one of tert-butyl hydroperoxide and sodium thiosulfate.

[0033] In a preferred embodiment of the present invention, 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.

[0034] The preparation method of the VDC-AN composition of this invention optimizes the preparation process by employing emulsion polymerization and optimizing factors affecting the reaction, such as polymerization steps, reaction temperature and time, feed formulation, and feed method. This effectively solves the problem of significant differences in the reactivity ratios of vinylidene chloride and acrylonitrile, as well as dyeing monomers, resulting in a VDC-AN composition with excellent copolymer structure. By introducing dyeing monomers and reducing the amount of emulsifier, 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.

[0035] In this invention, latex particles of suitable size are formed during the seed emulsion polymerization stage. During the feeding polymerization stage, the monomers in the feeding polymerization stage have a swelling effect on the latex particles formed in the previous seed emulsion polymerization stage (polymerization and swelling occur simultaneously). The introduction of a copolymer emulsifier ensures the stability of latex ions, and its unique flexible structure effectively improves the fiber's softness after spinning. Simultaneously, its shared carboxyl or sulfonic acid groups also exhibit good dyeing properties, resulting in superior fiber dyeing performance. The final composition, after mechanical demulsification, requires no washing process; residual auxiliaries and moisture are removed by flash evaporation before being dried in a fluidized bed to obtain a high flame-retardant acrylic resin.

[0036] Compared with existing technologies, the present invention has the following advantages:

[0037] 1. This invention adopts emulsion polymerization process. By optimizing factors affecting the reaction, such as polymerization steps, reaction temperature and time, feed formulation, and feed method, the preparation process is optimized. It 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 more uniform dyeing effect, and there will be no uneven color after dyeing.

[0038] 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.

[0039] 3. The composition obtained by the present invention does not require washing after mechanical demulsification. It can be dried after removing residual additives and moisture by flash evaporation to obtain the VDC-AN composition.

[0040] 4. The fiber produced by spinning the composition obtained by 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%. Attached Figure Description

[0041] Figure 1 These are SEM images of the resins in Example 4 and Comparative Example 1 of the present invention.

[0042] Figure 2 These are fiber SEM images of Embodiment 6 and Comparative Example 2 of the present invention.

[0043] 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

[0044] 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.

[0045] Example 1

[0046] A method for preparing a VDC-AN composition includes the following steps:

[0047] (1) Prepare reaction raw materials for later use.

[0048] The raw material formula is as follows:

[0049]

[0050] Polymerization initiator:

[0051] tert-butyl hydroperoxide (TBHP) 30g

[0052] Sculpting powder (SFS) 30g

[0053] Residue-reducing initiator:

[0054] 150g tert-butyl hydroperoxide

[0055] 150g of sculpting powder

[0056] 70kg of deionized water

[0057] (2) 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;

[0058] (3) Prepare the polymerization initiator aqueous solution: Weigh 30g of TBHP and prepare TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 30g of SFS and prepare SFS aqueous solution with 5Kg of deionized water for later use.

[0059] (4) 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.

[0060] (5) 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 (2) 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 (3) and 10% of the SFS aqueous solution prepared in step (3) at a uniform rate within 1h to react for 1h to obtain the seed emulsion.

[0061] (6) 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 (3) to the seed emulsion obtained in step (5) and react. After reacting for 8 hours, the reaction is stopped and the reaction product is obtained.

[0062] (7) 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 (4) 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 dryer at 45℃ to finally obtain the product.

[0063] Example 2

[0064] A method for preparing a VDC-AN composition includes the following steps:

[0065] (1) Prepare reaction raw materials for later use.

[0066] The raw material formula is as follows:

[0067]

[0068] Polymerization initiator:

[0069] 32g tert-butyl hydroperoxide

[0070] 32g of sculpting powder

[0071] Residue-reducing initiator:

[0072] 160g tert-butyl hydroperoxide

[0073] 160g of sculpting powder

[0074] 75kg of deionized water

[0075] (2) Prepare 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;

[0076] (3) Prepare the polymerization initiator aqueous solution: Weigh 32g of TBHP and prepare a TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 32g of SFS and prepare an SFS aqueous solution with 5Kg of deionized water for later use.

[0077] (4) 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.

[0078] (5) 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 (2) into the polymerization kettle, and cold disperse at a stirring speed of 80rpm for 25 minutes, and maintain this speed to raise the temperature to 55℃, and then uniformly add 5% of the TBHP aqueous solution prepared in step (3) and 5% of the SFS aqueous solution prepared in step (3) within 1h to react for 1.5h to obtain seed emulsion;

[0079] (6) 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 (3) to the seed emulsion obtained in step (5) and react for 4 hours to end the reaction and obtain the reaction product.

[0080] (7) 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 (4) 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℃, and finally the product is obtained.

[0081] Example 3

[0082] A method for preparing a VDC-AN composition includes the following steps:

[0083] (1) Prepare reaction raw materials for later use.

[0084] The raw material formula is as follows:

[0085]

[0086] Polymerization initiator:

[0087] 35g tert-butyl hydroperoxide

[0088] 35g of sculpting powder

[0089] Residue-reducing initiator:

[0090] 175g tert-butyl hydroperoxide

[0091] 175g of sculpting powder

[0092] 60kg of deionized water

[0093] (2) 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;

[0094] (3) 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.

[0095] (4) 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.

[0096] (5) 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, 1Kg acrylonitrile monomer, 60g sodium 2-acrylamide-2-methylpropanesulfonate, 12g isooctyl acrylate and 8% of the emulsifier aqueous solution prepared in step (2) into the polymerization kettle, and cold disperse at a stirring speed of 120rpm for 20 minutes. Maintain this speed and raise the temperature to 60℃. Then, add 8% of the TBHP aqueous solution prepared in step (3) and 8% of the SFS aqueous solution prepared in step (3) at a uniform rate within 1h to react for 2h to obtain seed emulsion;

[0097] (6) 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 (3) to the seed emulsion obtained in step (5) and react for 6 hours to end the reaction and obtain the reaction product.

[0098] (7) 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 (4) 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 dryer at 45℃ to finally obtain the product.

[0099] Example 4

[0100] A method for preparing a VDC-AN composition includes the following steps:

[0101] (1) Prepare reaction raw materials for later use.

[0102] The raw material formula is as follows:

[0103]

[0104] Polymerization initiator:

[0105] 32g tert-butyl hydroperoxide

[0106] 32g of sculpting powder

[0107] Residue-reducing initiator:

[0108] 150g tert-butyl hydroperoxide

[0109] 150g of sculpting powder

[0110] 72kg of deionized water

[0111] (2) Prepare 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;

[0112] (3) Prepare the polymerization initiator aqueous solution: Weigh 32g of TBHP and prepare a TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 32g of SFS and prepare an SFS aqueous solution with 5Kg of deionized water for later use.

[0113] (4) 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.

[0114] (5) 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 (2) 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 (3) and 8% of the SFS aqueous solution prepared in step (3) within 1.5h to react for 1.5h to obtain seed emulsion;

[0115] (6) 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 (3) to the seed emulsion obtained in step (5) and react for 6 hours to end the reaction and obtain the reaction product.

[0116] (7) 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 (4) are uniformly fed into the polymerization reactor within 30 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℃, and finally the product is obtained.

[0117] Example 5

[0118] A method for preparing a VDC-AN composition includes the following steps:

[0119] (1) Prepare reaction raw materials for later use.

[0120] The raw material formula is as follows:

[0121]

[0122] Polymerization initiator:

[0123] 34g tert-butyl hydroperoxide

[0124] 34g of sculpting powder

[0125] Residue-reducing initiator:

[0126] 170g tert-butyl hydroperoxide

[0127] 170g of sculpting powder

[0128] 65kg of deionized water

[0129] (2) Prepare 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;

[0130] (3) Prepare the 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.

[0131] (4) 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.

[0132] (5) 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 (2) 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 (3) and 10% of the SFS aqueous solution prepared in step (3) within 1h to react for 1h to obtain seed emulsion;

[0133] (6) 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 (3) to the seed emulsion obtained in step (5) and react. After reacting for 4 hours, the reaction is stopped and the reaction product is obtained.

[0134] (7) 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 (4) 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 dryer at a drying temperature of 50℃ to finally obtain the product.

[0135] Example 6

[0136] A method for preparing a VDC-AN composition includes the following steps:

[0137] (1) Prepare reaction raw materials for later use.

[0138] The raw material formula is as follows:

[0139]

[0140] Polymerization initiator:

[0141] 30g tert-butyl hydroperoxide

[0142] 30g of sculpting powder

[0143] Residue-reducing initiator:

[0144] 150g tert-butyl hydroperoxide

[0145] 150g of sculpting powder

[0146] 70kg of deionized water

[0147] (2) 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;

[0148] (3) Prepare the polymerization initiator aqueous solution: Weigh 30g of TBHP and prepare TBHP aqueous solution with 5Kg of deionized water for later use; Weigh 30g of SFS and prepare SFS aqueous solution with 5Kg of deionized water for later use.

[0149] (4) 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.

[0150] (5) 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 (2) 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 (3) and 8% of the SFS aqueous solution prepared in step (3) at a uniform rate within 1h to react. The reaction time is 1.5h to obtain the seed emulsion.

[0151] (6) 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 n-butyl acrylate, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (3) to the seed emulsion obtained in step (5) and react for 6h. The reaction is then stopped to obtain the reaction product.

[0152] (7) 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 (4) 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℃, and finally the product is obtained.

[0153] Comparative Example 1

[0154] A mixture of modified polyacrylonitrile prepared according to the method described in Example 1 of CN104558392A.

[0155] Comparative Example 2

[0156] Acrylic copolymer latex prepared according to the method described in Example 1 of CN107734988A.

[0157] Performance testing

[0158] The compositions obtained in Examples 1-6 and Comparative Examples 1-2 were used to prepare spun fibers. The preparation process is as follows:

[0159] 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:

[0160] Fiber strength testing: Performed according to the methods specified in GB / T 14337-2022 "Test Method for Tensile Properties of Chemical Fibers (Short Fibers)";

[0161] Color uptake rate: Performed according to the method specified in FZ / T 50024-2014 "Test Method for Color Uptake Rate of Acrylic Fiber";

[0162] 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".

[0163]

[0164]

Claims

1. A process for the preparation of a VDC-AN combination, characterized in that, It comprises the following steps: (1) Prepare reaction raw materials for standby The reaction raw material composition is as follows in weight fraction: Vinylidene chloride monomer 5-20 parts Acrylonitrile monomer 5-20 parts Dyeing monomer 0.1-1 part Acrylate monomer 0.1-0.8 part Copolymerization type emulsifier 0.1-1 part Initiator 0.1-0.5 part Deionized water 50-100 parts The acrylate monomer is one of methyl acrylate, n-butyl acrylate, and isooctyl acrylate, and the copolymerization type emulsifier is one of double bond group containing bisalkyl sulfosuccinic acid, double bond group containing alkyl alcohol ether sulfuric acid, and allyl polyether phosphate. (2) Prepare an emulsifier aqueous solution: prepare an emulsifier aqueous solution by mixing the copolymerization type emulsifier with 3-10% deionized water, for standby; (3) Prepare a polymerization initiator aqueous solution: prepare a polymerization initiator aqueous solution by mixing 15-20% initiator with 10-20% deionized water, for standby; (4) Prepare a residual removal initiator aqueous solution: prepare a residual removal initiator aqueous solution by mixing the remaining initiator with 5-10% deionized water, for standby; (5) Seed emulsion polymerization: add the remaining deionized water, 5-10% vinylidene chloride monomer, 5-10% acrylonitrile monomer, 5-10% dyeing monomer, 5-10% acrylate monomer, and 5-10% emulsifier aqueous solution into a polymerization kettle, cold disperse for 15-35 minutes at a stirring speed of 80-150 rpm, heat to 45-75°C, and add 5-10% polymerization initiator aqueous solution for reaction, with a reaction time of 0.5-2.5 h, to obtain a seed emulsion; (6) Feeding polymerization: add the remaining vinylidene chloride monomer, the remaining acrylonitrile monomer, the remaining dyeing monomer, the remaining acrylate monomer, the remaining emulsifier aqueous solution, and the remaining polymerization initiator aqueous solution into the seed emulsion obtained above at a temperature of 45-75°C and a stirring speed of 80-150 rpm for reaction, with a reaction time of 4-8 h, to obtain a reaction product; (7) Post-treatment: add the residual removal initiator aqueous solution into the reaction product obtained in step (6) at a temperature of 45-75°C and a stirring speed of 80-150 rpm for reaction, with a reaction time of 0.5-1.5 h, and then discharge after cooling, break the emulsion, flash evaporate, and dry, to obtain a VDC-AN composition.

2. The method of preparing a VDC-AN composition according to claim 1, characterized in that, The polymerization kettle is vacuumed before seed emulsion polymerization.

3. The method of making a VDC-AN combination of claim 1, wherein, The dyeing monomer is at least one of allyl sulfonic acid, methacryl sulfonic acid, isoprene sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, and metal and amine salts thereof.

4. The method of making a VDC-AN combination of claim 1, wherein, The double bond containing group of the double alkyl sulfosuccinic acid has the following structure: wherein R1 is a C6 to C 14 straight chain or branched alkyl group, R2 is a C6 to C 14 straight chain or branched alkyl group, and R3 is a H group or a C1 to C3 straight chain or branched alkyl group.

5. The method of making a VDC-AN combination of claim 1, wherein, The double bond-containing alkyl alcohol ether sulfate has the following structural formula: wherein a ranges from 2 to 10 and b ranges from 2 to 8.

6. The method of making a VDC-AN combination of claim 1, wherein, The allyl polyether phosphate has the following structural formula: wherein n ranges from 2 to 12.

7. The method of making a VDC-AN composition of claim 1, wherein, The initiator is at least one of tert-butyl peroxide and white powder.

8. The method of making a VDC-AN combination of claim 1, wherein, The flash evaporation temperature in step (7) is 60-80°C, and the pressure is -0.09 to -0.01 Mpa; the drying temperature is 35-70°C.

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