Superabsorbent Resin Prepared from Acrylic Fibre Waste Silk and Its Preparation Method

Abstract

The present invention relates to a superabsorbent resin prepared from acrylic fiber waste silk and a preparation method thereof, belonging to the technical field of polymer materials. The superabsorbent resin prepared from acrylic fiber waste silk according to the present invention is prepared by copolymerizing a hydrolyzate of acrylic fiber waste silk, acrylamide and acrylate. The superabsorbent resin prepared from acrylic fiber waste silk according to the present invention makes full use of waste materials, is energy-saving and environmentally friendly, and the water absorption rate and gel strength of the resin are significantly improved; at the same time, the present invention provides a simple and convenient preparation method.

Description

Technical Field

[0001] The present invention relates to a superabsorbent resin prepared from acrylic fiber waste silk and a preparation method thereof, belonging to the technical field of polymer materials. Background Art

[0002] A superabsorbent resin (abbreviation: SAP) is a hydrophilic macromolecular compound with a network structure and low cross-linking degree, which has the characteristics of being insoluble in water and oil, but can absorb water up to hundreds or even thousands of times its own weight, and has a fast water absorption rate, is not easy to lose water, and even if pressurized, the water in the resin will not precipitate, with strong water retention ability.

[0003] Since the establishment of the Flory theory in the 1950s and 1960s of the last century, superabsorbent resins have developed into a discipline with various types, multiple uses, large production, and in-depth theoretical research at home and abroad. Its products mainly include five major series: non-ionic, anionic, cationic, zwitterionic and various hydrophilic groups, including sulfonic acid type, carboxylic acid type, phosphoric acid type, tertiary amine, quaternary ammonium, amide, ether type, starch and their combined types. The highest water absorption rate of the product can reach 5000 g / g water absorption multiple. It is widely used in many industries such as agriculture, forestry and horticulture, medicine, physiological hygiene products, construction, fire-fighting materials, daily chemicals, papermaking, oilfield chemicals, etc. The main raw materials used in the above five series of superabsorbent resins are acrylic acid, acrylamide, acrylonitrile, sodium acrylate, sulfonate, tertiary amine salt, quaternary ammonium salt, starch, etc.

[0004] Based on the mechanism that polyacrylonitrile can be hydrolyzed into polyacrylamide and polyacrylic acid (sodium), and the component of acrylic fiber waste silk is polyacrylonitrile, this provides a theoretical basis for the treatment and application of acrylic fiber waste silk. In the production process of acrylic fiber, it is inevitable to produce about 1% of the total amount of polyacrylonitrile such as waste silk, waste polyacrylonitrile powder, pellets, etc., which are difficult to handle and pollute the environment. After hydrolyzing this waste material, various polymer materials can be synthesized. Among them, making superabsorbent resin by hydrolyzing acrylic fiber waste silk is an effective way to turn waste into treasure.

[0005] Zhou Guowei mentioned the hydrolysis method of acrylic fiber waste silk in "Hydrolysis and Application of Acrylic Fiber Waste Silk". After hydrolysis, it can be made into flocculants, water shutoff agents, adhesives and superabsorbent resins, etc. The pH value needs to be adjusted before cross-linking in the process of preparing the water absorbent.

[0006] Li Liuzhong discussed the optimal process conditions for the hydrolysis of acrylic fiber waste silk and successfully carried out industrial production in "Preparation of Polymer Thickener with Waste Acrylic Fiber". Since it is used as a thickener, a higher molecular weight is required, while the molecular weight of waste acrylic fiber is often low and needs to be chain-extended to increase the molecular weight. Therefore, it is relatively difficult to prepare a thickener using waste acrylic fiber.

[0007] Li Denghao prepared a resin with a water absorption rate of 480-500g / g and a salt water absorption rate of 61g / g (0.9% salt water) in "Preparation of Super Absorbent Resin from Acrylic Waste". However, in this preparation method, hydrochloric acid is used to adjust the pH value of the hydrolysis product to 6-7 before adding the crosslinking agent, which is not only cumbersome, but also hydrochloric acid is now a precursor of drugs and is no longer recommended. Once the hydrolysis is incomplete, the excess alkali will affect the crosslinking reaction, thereby affecting the product performance. Summary of the invention

[0008] The purpose of the present invention is to provide a highly water-absorbent resin prepared from waste acrylic fibers, which fully utilizes waste materials, is energy-saving and environmentally friendly, and significantly improves the water absorption rate and gel strength of the resin; at the same time, the present invention provides a simple and convenient preparation method.

[0009] The highly water-absorbent resin prepared by using waste acrylic fibers is prepared by copolymerizing hydrolyzate of waste acrylic fibers, acrylamide and acrylate.

[0010] The preparation process of the acrylic waste hydrolyzate (PAAM) is as follows:

[0011] Wash the acrylic waste silk with distilled water, cut it into pieces, mix it with alkali and water in a certain proportion, add it into a flask, heat it to the specified temperature in a water bath, and hydrolyze it for a certain period of time to obtain the product.

[0012] Preferably, the mass ratio of acrylic waste silk to alkali and water is 1:0.5-1.0:5-10.

[0013] Preferably, the hydrolysis reaction temperature is 80-95° C., the reaction time is 4-10 hours, and the acrylic waste hydrolyzate with a mass concentration of 13-23% is obtained.

[0014] The acrylic waste yarn is long and short yarns without utilization value produced in the acrylic production process. The acrylic waste yarn discarded by textile factories or polyacrylonitrile waste can be used as the hydrolysis raw material of the present invention.

[0015] The acrylic acid ester is preferably methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like, and is more preferably vinyl acetate.

[0016] The method for preparing a highly water-absorbent resin using acrylic waste silk comprises the following steps:

[0017] (1) Add hydrolyzate of acrylic fiber waste silk (PAAM), acrylamide (AM), acrylate, crosslinking agent and water into a reactor equipped with stirring and constant temperature water bath heating. Start stirring, purge with nitrogen to remove oxygen. After heating to the specified temperature, add the initiator to start the copolymerization reaction. As the polymerization reaction proceeds, the viscosity of the polymerization system increases. Stop stirring and nitrogen, and the reaction proceeds smoothly. After a certain reaction time, an elastic hydrogel is obtained.

[0018] (2) Crush, granulate, dry, pulverize and screen the hydrogel to obtain white powder particles of a certain mesh number, and obtain the high water absorbent resin described above. Test the water absorption rate and gel strength after water absorption of the product.

[0019] The copolymerization described in the present invention adopts aqueous solution polymerization and belongs to the category of free radical polymerization.

[0020] Preferably, the mass ratio of hydrolyzate of acrylic fiber waste silk, acrylamide and acrylate is (5-9):(1-5):(1-3), based on dry basis, and the rest is distilled water, and the total system mass concentration is 20-30%.

[0021] Preferably, the crosslinking agent is N,N-methylenebisacrylamide (MBA), and the addition amount is 0.01-0.1% of the total mass of the monomers.

[0022] Preferably, the initiator is an ammonium persulfate-sodium bisulfite-azodiisobutyramidine hydrochloride (V-50) composite initiator, and the ratio of the three initiators is 1:1:10. The addition amounts respectively account for 0.01-0.05%, 0.01-0.05% and 0.1-0.5% of the total mass of the monomers.

[0023] Preferably, the initial temperature of the polymerization reaction is 10-60 °C, and the polymerization reaction time is 4-8 hours.

[0024] Preferably, the drying temperature of the hydrogel is 60-90 °C, and the drying time is adjusted based on the product solid content of 92-96%. The final product particle size is 80-100 mesh.

[0025] In the present invention, considering the preparation of high water absorbent resin solely from waste acrylic fiber, not only the water absorption performance of the final product cannot meet the higher requirements, but also the excessive alkali is not easy to remove during the hydrolysis reaction, and it cannot be simply neutralized by hydrochloric acid, sulfuric acid, etc. which are basically prohibited at present. Acrylamide which can increase the molecular weight and is extremely easy to hydrolyze is added to neutralize the excessive alkali, simplifying the preparation process. In addition, the hydrophobic monomer acrylate ensures the compressive strength of the high water absorbent, greatly improving the product performance indicators.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention utilizes the acrylic fiber waste silk generated during the production process of acrylic fiber. After hydrolysis, it is copolymerized with acrylamide and acrylate to prepare a superabsorbent resin with high water absorption rate and high strength of the hydrogel formed after water absorption.

[0028] (2) The present invention enables the secondary utilization of the acrylic fiber waste silk, which is the by - product formed during the production process of acrylic fiber. At the same time, due to the addition of the hydrophobic monomer vinyl acetate and the copolymerization initiated by a low - temperature composite initiator, the water absorption rate and gel strength of the resin are improved.

[0029] (3) The resin prepared by the present invention can be used in aspects such as water retention in agricultural soil and forest greening in arid areas, effectively utilizing the difficult - to - handle acrylic fiber waste silk. Specific Embodiments

[0030] The present invention will be described in detail below through specific embodiments, but the present invention is not limited to these embodiments.

[0031] In the experiments, the monomers acrylamide (AM) and vinyl acetate (VAc) are both of polymerization grade, the conductivity of deionized water is ≤5 μs / cm, the cross - linker and initiator are both analytical pure reagents, and the nitrogen is high - purity nitrogen.

[0032] Example 1

[0033] a. Preparation of the hydrolysis product of acrylic fiber waste silk

[0034] 100 g of washed and shredded acrylic fiber waste silk, 50 g of sodium hydroxide, and 500 g of distilled water are added to a 1000 - ml flask equipped with a reflux condenser, a thermometer, and a stirrer. The mixture is heated in a water bath to 80°C and refluxed for 4 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 23%, which is reserved as the raw material for the next copolymerization step.

[0035] b. Preparation of superabsorbent resin by ternary copolymerization

[0036] 304 g of PAAM with a concentration of 23% prepared in step a, 20 g of AM, 10 g of VAc, 166 g of distilled water, and 0.01 g of cross - linker N,N - methylenebisacrylamide (MBA) are added to a sealed polymerization container with a stirrer. The stirrer is started to stir at a low speed, and nitrogen is introduced to remove oxygen. The temperature of the mixed material liquid is adjusted to 20°C. When the oxygen content in the liquid in the polymerization vessel drops to 0.02 mg / L, 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azodiisobutyramidine hydrochloride (V - 50) are added. The polymerization reaction immediately starts, and the viscosity of the system increases significantly. At this time, the stirring and nitrogen can be stopped, and the polymerization is allowed to proceed statically for 4 hours to obtain a colloid with rubber - like elasticity.

[0037] c. Post - treatment of the elastic colloid

[0038] The elastic colloid prepared from b is cut into small pieces and fed into a granulator for granulation, and then dried at 60 - 90 °C for 2 - 4 hours (until the solid content reaches 92 - 96%), and finally pulverized and sieved. The 80 - 100 mesh fraction is taken as the required target product, namely the superabsorbent resin.

[0039] d. The superabsorbent resin prepared from c is subjected to water absorption rate measurement and gel strength measurement after water absorption. The results are shown in Table 1.

[0040] Comparative Example 1

[0041] The preparation method of this comparative example is the same as that of Example 1, except that vinyl acetate is not added in the copolymerization. Specifically as follows:

[0042] a. Preparation of the hydrolysis product of acrylic fiber waste silk

[0043] 100 g of washed and shredded acrylic fiber waste silk, 50 g of sodium hydroxide, and 500 g of distilled water are added to a 1000 ml flask equipped with a reflux condenser, thermometer, and stirrer. The mixture is heated in a water bath to 80 °C and refluxed for 4 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 23%, which is reserved as the raw material for the next copolymerization.

[0044] b. Preparation of superabsorbent resin by binary copolymerization

[0045] 304 g of 23% PAAM prepared from a, 20 g of AM, 166 g of distilled water, and 0.01 g of cross - linker N,N - methylenebisacrylamide (MBA) are added to a sealed polymerization container with stirring. The stirrer is started and stirred at a low speed, and nitrogen is introduced to remove oxygen. The temperature of the mixed material liquid is adjusted to 20 °C. When the oxygen content in the liquid in the polymerization vessel drops to 0.02 mg / L, 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azodiisobutyramidine hydrochloride (V - 50) are added. The polymerization reaction immediately starts, and the viscosity of the system increases significantly. At this time, stirring and nitrogen can be stopped, and the polymerization is allowed to proceed statically for 4 hours to obtain a colloid with rubber - like elasticity.

[0046] c. Post - treatment of the elastic colloid

[0047] The elastic colloid prepared from b is cut into small pieces and fed into a granulator for granulation, and then dried at 60 - 90 °C for 2 - 4 hours (until the solid content reaches 92 - 96%), and finally pulverized and sieved. The 80 - 100 mesh fraction is taken as the required target product, namely the superabsorbent resin.

[0048] d. The superabsorbent resin prepared from c is subjected to water absorption rate measurement and gel strength measurement after water absorption. The results are shown in Table 1.

[0049] Example 2

[0050] This example is about increasing the dosage of the hydrolysis agent sodium hydroxide, specifically as follows:

[0051] a. Preparation of the hydrolysis product of acrylic fiber waste silk

[0052] Add 100 g of washed and shredded acrylic fiber waste silk, 80 g of sodium hydroxide, and 800 g of distilled water into a 2000 ml flask equipped with a reflux condenser, a thermometer, and a stirrer. Heat it in a water bath to 80 °C and carry out a reflux reaction for 4 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 19%, which is reserved as the raw material for the next copolymerization.

[0053] b. Preparation of superabsorbent resin by terpolymerization

[0054] Add 368 g of 19% PAAM prepared in a, 20 g of AM, 10 g of VAc, 102 g of distilled water, and 0.01 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) into a sealed polymerization container with a stirrer. Start the stirrer and stir at a low speed, introduce nitrogen to remove oxygen, adjust the temperature of the mixed material liquid to 20 °C. When the oxygen content in the liquid in the polymerization vessel drops to 0.02 mg / L, add 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azobisisobutyramidine hydrochloride (V-50). The polymerization reaction will immediately start, and the viscosity of the system will increase significantly. At this time, the stirring and nitrogen can be stopped, and static polymerization is carried out for 4 hours to obtain a colloid similar to rubber elasticity.

[0055] c. Post-treatment of the elastic colloid

[0056] Cut the elastic colloid obtained in b into small pieces and put them into a granulator for granulation, then dry them at 60 - 90 °C for 2 - 4 hours (based on the solid content reaching 92 - 96%), and finally carry out crushing and sieving. Take the 80 - 100 mesh as the required target product, that is, the superabsorbent resin.

[0057] d. Take the superabsorbent resin obtained in c for water absorption rate measurement and gel strength measurement after water absorption. The results are shown in Table 1.

[0058] Comparative Example 2

[0059] The preparation method of this comparative example is the same as that of Example 2, except that vinyl acetate is not added in the copolymerization, specifically as follows:

[0060] a. Preparation of the hydrolysis product of acrylic fiber waste silk

[0061] Add 100 g of washed and shredded acrylic fiber waste silk, 80 g of sodium hydroxide, and 800 g of distilled water into a 2000 ml flask equipped with a reflux condenser, a thermometer, and a stirrer. Heat it in a water bath to 80 °C and carry out a reflux reaction for 4 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 19%, which is reserved as the raw material for the next copolymerization.

[0062] b. Preparation of superabsorbent resin by binary copolymerization

[0063] 368 g of 19% PAAM prepared in a, 20 g of AM, 112 g of distilled water, and 0.01 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) were added into a sealed polymerization container with stirring. The stirrer was started to stir at a low speed, and nitrogen was introduced to remove oxygen. The temperature of the mixed material liquid was adjusted to 20 °C. When the oxygen content in the liquid in the polymerization vessel dropped to 0.02 mg / L, 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azobisisobutyramidine hydrochloride (V-50) were added. The polymerization reaction immediately started, and the viscosity of the system increased significantly. At this time, the stirring and nitrogen could be stopped, and the polymerization was allowed to stand for 4 hours to obtain a colloid similar to rubber elasticity.

[0064] c. Post-treatment of elastic colloid

[0065] The elastic colloid prepared in b was cut into small pieces and granulated in a granulator, and then dried at 60 - 90 °C for 2 - 4 hours (until the solid content reached 92 - 96%), and finally pulverized and sieved. The 80 - 100 mesh was taken as the required target product, that is, the superabsorbent resin.

[0066] d. The superabsorbent resin prepared in c was taken for water absorption rate measurement and gel strength measurement after water absorption. The results are shown in Table 1.

[0067] Example 3

[0068] a. Preparation of hydrolysis product of acrylic fiber waste silk

[0069] 100 g of washed and shredded acrylic fiber waste silk, 100 g of sodium hydroxide, and 1000 g of distilled water were added into a 2000 ml flask equipped with a reflux condenser, a thermometer, and a stirrer. The water bath was heated to 90 °C, and the reflux reaction was carried out for 4 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 23%, which was used as the raw material for the next copolymerization.

[0070] b. Preparation of superabsorbent resin by ternary copolymerization

[0071] 304 g of 23% PAAM prepared in a, 20 g of AM, 10 g of ethyl acrylate, 166 g of distilled water, and 0.01 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) were added into a sealed polymerization container with stirring. The stirrer was started to stir at a low speed, and nitrogen was introduced to remove oxygen. The temperature of the mixed material liquid was adjusted to 20 °C. When the oxygen content in the liquid in the polymerization vessel dropped to 0.02 mg / L, 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azobisisobutyramidine hydrochloride (V-50) were added. The polymerization reaction immediately started, and the viscosity of the system increased significantly. At this time, the stirring and nitrogen could be stopped, and the polymerization was allowed to stand for 4 hours to obtain a colloid similar to rubber elasticity.

[0072] c. Post-treatment of the elastic colloid

[0073] Cut the elastic colloid obtained in step b into small pieces and granulate them in a granulator, then dry them at 60 - 90 °C for 2 - 4 hours (until the solid content reaches 92 - 96%), and finally pulverize and screen them. Take the 80 - 100 mesh as the required target product, namely the superabsorbent resin.

[0074] d. Take the superabsorbent resin obtained in step c and measure its water absorption rate and gel strength after water absorption. The results are shown in Table 1.

[0075] Comparative Example 3

[0076] The hydrolysis part of this example is the same as that in step a of Example 3. VAc is not added in the copolymerization, and the rest are the same as in Example 3. The results are shown in Table 1.

[0077] Examples 4, 5

[0078] In Example 4, the hydrolysis reflux reaction time is increased to 6 hours, and in Example 5, the hydrolysis reflux reaction time is increased to 8 hours. The rest of the steps are the same as in Example 1. The results are shown in Table 1.

[0079] Examples 6, 7, 8, 9

[0080] In Example 6, the hydrolysis reflux reaction time is increased to 6 hours, and in Example 7, the hydrolysis reflux reaction time is increased to 8 hours. The rest of the steps are the same as in Example 2. In Example 8, the hydrolysis reflux reaction time is increased to 6 hours, and in Example 9, the hydrolysis reflux reaction time is increased to 8 hours. The rest of the steps are the same as in Example 3. The results are shown in Table 1.

[0081] Example 10

[0082] The formulation and process conditions of this example are the same as those in Example 1, except that the reflux reaction temperature is increased to 95 °C. The results are shown in Table 1.

[0083] Comparative Example 4

[0084] VAc is not added in the copolymerization part of this example, and the other process conditions are the same as those in Example 10. The obtained results are shown in Table 1.

[0085] Example 11

[0086] In this example, the dosage of the hydrolysis agent, the reflux reaction temperature and the reflux reaction time are increased. Specifically as follows:

[0087] a. Preparation of the hydrolysis product of acrylic fiber waste silk

[0088] Add 100 g of washed and shredded acrylic waste silk, 100 g of sodium hydroxide, and 1000 g of distilled water into a 2000 ml flask equipped with a reflux condenser, a thermometer, and a stirrer. Heat it in a water bath to 95 °C and carry out a reflux reaction for 8 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 17%, which is reserved as the raw material for the next copolymerization step.

[0089] b. Preparation of superabsorbent resin by ternary copolymerization

[0090] Add 412 g of 17% PAAM prepared in step a, 20 g of AM, 10 g of VAc, 58 g of distilled water, and 0.01 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) into a sealed polymerization container with a stirrer. Start the stirrer and stir at a low speed. Pass nitrogen to remove oxygen. Adjust the temperature of the mixed material liquid to 20 °C. When the oxygen content in the liquid in the polymerization vessel drops to 0.02 mg / L, add 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azodiisobutyramidine hydrochloride (V-50). The polymerization reaction will start immediately, and the viscosity of the system will increase significantly. At this time, stop stirring and nitrogen, and let it polymerize statically for 4 hours to obtain a colloid with rubber elasticity.

[0091] Steps c and d are the same as those in Example 1, and the obtained results are shown in Table 1.

[0092] Comparative Example 5

[0093] In this example, VAc is not added in the copolymerization part, and other process conditions are the same as those in Example 11. The obtained results are shown in Table 1.

[0094] The following examples are examples of changing the copolymerization conditions.

[0095] Example 12

[0096] a. Preparation of hydrolysis product of acrylic waste silk

[0097] The hydrolysis product is prepared under the process conditions of Example 11. The hydrolysis solution PAAM has a concentration of about 17% and is reserved as the raw material for the next copolymerization step.

[0098] b. Preparation of superabsorbent resin by ternary copolymerization

[0099] 412 g of 17% PAAM prepared from a, 20 g of AM, 10 g of VAc, 58 g of distilled water, 0.05 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) were added into a sealed polymerization container with stirring. The stirrer was started to stir at a low speed, and nitrogen was introduced to remove oxygen. The temperature of the mixed material liquid was adjusted to 20 °C. When the oxygen content in the liquid in the polymerization vessel dropped to 0.02 mg / L, 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of azodiisobutyramidine hydrochloride (V-50) were added. The polymerization reaction immediately started, and the viscosity of the system increased significantly. At this time, the stirring and nitrogen could be stopped, and the static polymerization was carried out for 4 hours to obtain a colloid with rubber elasticity.

[0100] Steps c and d are the same as those in Example 1, and the obtained results are shown in Table 1.

[0101] Example 13

[0102] Same as Example 12, except that 0.1 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) was used, and the obtained results are shown in Table 1.

[0103] Examples 14, 15

[0104] In Examples 14 and 15, the addition amounts of the initiator redox system were increased to 0.03 g and 0.05 g respectively, and the addition amount of azo V-50 was increased to 0.3 g and 0.5 g respectively. The rest was the same as in Example 12, and the obtained results are shown in Table 1.

[0105] Examples 16, 17, 18

[0106] Same as Example 12, except that the copolymerization reaction time was increased to 6, 8, and 10 hours, and the obtained results are shown in Table 1.

[0107] Example 19

[0108] Same as Example 12, where the changed conditions were: the redox initiator was increased to 0.03 g and 0.03 g respectively, the addition amount of azo V-50 was increased to 0.3 g, and the copolymerization reaction time was increased to 10 hours. The obtained results are shown in Table 1.

[0109] Comparative Example 6

[0110] Same as Example 19, except that VAc was not added in the copolymerization, and the obtained results are shown in Table 1.

[0111] In the following Examples 20 and 21, the polymerization concentration of the polymerization system was increased to 25% and 30%.

[0112] Example 20

[0113] a. Preparation of hydrolysis product of acrylic fiber waste silk

[0114] Add 100 g of washed and shredded acrylic waste silk, 100 g of sodium hydroxide, and 500 g of distilled water into a 1000 ml flask equipped with a reflux condenser, a thermometer, and a stirrer. Heat it in a water bath to 95 °C and carry out a reflux reaction for 8 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 29%, which is reserved as the raw material for the next copolymerization.

[0115] b. Preparation of superabsorbent resin by ternary copolymerization

[0116] Add 241 g of 29% PAAM prepared in a, 20 g of AM, 10 g of VAc, 129 g of distilled water, and 0.05 g of crosslinking agent N,N'-methylenebisacrylamide (MBA) into a closed polymerization container with a stirrer. Start the stirrer and stir at a low speed. Pass nitrogen to remove oxygen. Adjust the temperature of the mixed material liquid to 20 °C. When the oxygen content in the liquid in the polymerization vessel drops to 0.02 mg / L, add 0.03 g of ammonium persulfate and 0.03 g of sodium bisulfite, and 0.3 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50). The polymerization reaction will immediately start, and the viscosity of the system will increase significantly. At this time, stop stirring and passing nitrogen, and let it polymerize statically for 8 hours to obtain a colloid similar to rubber elasticity.

[0117] c. Post-treatment of elastic colloid

[0118] Cut the elastic colloid prepared in b into small pieces and feed them into a granulator for granulation. Then dry them at 60 - 90 °C for 2 - 4 hours (based on the solid content reaching 92 - 96%), and finally carry out crushing and sieving. Take the 80 - 100 mesh as the required target product, that is, the superabsorbent resin.

[0119] d. Take the superabsorbent resin prepared in c and carry out water absorption rate measurement and gel strength measurement after water absorption. The results are shown in Table 1.

[0120] Example 21

[0121] Same as Example 20, except that the amount of distilled water added is reduced to 62 g, that is, the polymerization concentration of the system is 30%. The results are shown in Table 1.

[0122] The following examples are test examples of changing the polymerization initiation temperature.

[0123] Examples 22, 23, 24, 25, 26

[0124] The specific steps of these five examples are the same as those of Example 1, except that the polymerization initiation temperatures are 10, 30, 40, 50, and 60 °C respectively. The results are shown in Table 1.

[0125] Comparative Example 7

[0126] Acrylamide was not added in this example.

[0127] a. Preparation of hydrolysis product of acrylic waste silk

[0128] Add 100 g of washed and shredded acrylic waste silk, 50 g of sodium hydroxide, and 500 g of distilled water into a 1000 ml flask equipped with a reflux condenser, a thermometer, and a stirrer. Heat it in a water bath to 80 °C and carry out a reflux reaction for 4 hours to obtain a slightly yellow viscous hydrolysis solution PAAM with a concentration of about 23%, which is reserved as the raw material for the next copolymerization.

[0129] b. Preparation of superabsorbent resin by binary copolymerization

[0130] Add 304 g of 23% PAAM prepared in a, 10 g of VAc, 166 g of distilled water, and 0.01 g of cross-linking agent N,N'-methylenebisacrylamide (MBA) into a sealed polymerization container with a stirrer. Start the stirrer and stir at a low speed. Pass nitrogen to remove oxygen. Adjust the temperature of the mixed material liquid to 20 °C. When the oxygen content in the liquid in the polymerization reactor drops to 0.02 mg / L, add 0.01 g of ammonium persulfate and 0.01 g of sodium bisulfite, and 0.1 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50). The polymerization reaction will start immediately, and the viscosity of the system will increase significantly. At this time, the stirring and nitrogen can be stopped, and static polymerization is carried out for 4 hours to obtain a colloid with rubber elasticity.

[0131] c. Post-treatment of elastic colloid

[0132] Cut the elastic colloid prepared in b into small pieces and enter a granulator for granulation. Then dry it at 60 - 90 °C for 2 - 4 hours (based on the solid content reaching 92 - 96%). Finally, carry out pulverization and sieving, and take 80 - 100 mesh as the required target product, that is, the superabsorbent resin.

[0133] d. Take the superabsorbent resin prepared in c for water absorption rate measurement and gel strength measurement after water absorption. The results are shown in Table 1.

[0134] Table 1 Water absorption multiple and gel strength after water absorption of superabsorbent resin

[0135]

[0136]

Claims

1. Preparation method of superabsorbent resin prepared from acrylic waste silk, characterized in that: It includes the following steps: (1) Add acrylic waste silk hydrolyzate, acrylamide, vinyl acetate, crosslinking agent and water into a reactor with stirring and constant temperature water bath heating. Start stirring, blow nitrogen to remove oxygen. After heating to the specified temperature, add initiator to start copolymerization reaction; (2) After the reaction is completed, an elastic hydrogel is obtained. The hydrogel is shredded, granulated, dried, pulverized and sieved to obtain the superabsorbent resin; The mass ratio of acrylic waste silk hydrolyzate, acrylamide and vinyl acetate is (5-9):(1-5):(1-3). Based on dry basis, the total system mass concentration is 20-25%; The starting temperature of the polymerization reaction is 10-30°C.

2. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 1, characterized in that: The preparation process of acrylic waste silk hydrolyzate is as follows: Wash the acrylic waste silk with distilled water, cut it into pieces, mix it with alkali and water in a certain proportion, add it into a flask, and use a water bath to heat up to the specified temperature, and carry out hydrolysis reaction for a certain time to obtain it.

3. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 2, characterized in that: The mass ratio of acrylic waste silk to alkali and water is 1:0.5-1.0:5-10.

4. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 2, characterized in that: The hydrolysis reaction temperature is 80-95°C, and the reaction time is 4-10 hours to obtain an acrylic waste silk hydrolyzate with a mass concentration of 13-23%.

5. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 1, characterized in that: The crosslinking agent is N,N-methylenebisacrylamide, and the addition amount is 0.01-0.1% of the total mass of the monomers.

6. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 1, characterized in that: The initiator is ammonium persulfate-sodium bisulfite-azodiisobutyramidine hydrochloride composite initiator, and the ratio of the three initiators is 1:1:

10. The addition amounts respectively account for 0.01-0.05%, 0.01-0.05%, and 0.1-0.5% of the total mass of the monomers.

7. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 1, characterized in that: The polymerization reaction time is 4-8 hours.

8. The preparation method of superabsorbent resin prepared from acrylic waste silk according to claim 1, characterized in that: The drying temperature of the hydrogel is 60-90°C, and the drying time is adjusted based on the product solid content of 92-96%. The final product particle size is 80-100 mesh.

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