A biodegradable high-solid-content enhanced water filter agent and its preparation method and application

Abstract

The present invention discloses a biodegradable high-solid content enhanced water filter agent and its preparation method and application. The biodegradable high-solid content enhanced water filter agent comprises the following raw materials: an anionic polyacrylamide intermediate, an aqueous dialdehyde starch solution, and a cationic etherifying agent. The anionic polyacrylamide intermediate comprises the following raw materials: acrylamide, an anionic monomer, a molecular weight regulator, a crosslinking monomer, and an initiator. This water filter agent can not only improve the dry strength and wet strength of paper, but also improve water filtration and retention. Moreover, the product has good stability, a high solid content, reaching 20% - 30%, does not gel after storage at room temperature for 3 months, can completely replace GPAM, and is biodegradable and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of paper strengthening water filters, and particularly to a biodegradable high-solid-content strengthening water filter and its preparation method and application. Background Art

[0002] At present, in the market, a large amount of polyacrylamide dry strength agents, starches, polyvinyl alcohols, etc. are mostly used to improve the strength of paper. However, after using the polyacrylamide dry strength agent, the water filtration becomes slower, affecting the paper machine speed; while using starch for paper strengthening, there are also problems such as low retention rate and easy spoilage of white water. For this reason, domestic and foreign counterparts have successively developed glyoxal-modified polyacrylamide (GPAM) to improve the strength and water filtration of paper. However, GPAM generally has poor stability and is prone to gelation. To extend the storage period, the solid content of GPAM is generally only made below 12%, and it needs to be stored at low temperature, resulting in high transportation and storage costs. In addition, GPAM cannot be biodegradable. Summary of the Invention

[0003] To overcome the above disadvantages, the purpose of the present invention is to provide a biodegradable high-solid-content strengthening water filter and its preparation method and application. This water filter can not only improve the dry strength and wet strength of paper, but also improve water filtration and retention, and the product has good stability, high solid content, reaching 20% - 30%, and does not gel after being stored at room temperature for 3 months.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: a biodegradable high-solid-content strengthening water filter, comprising the following raw materials: anionic polyacrylamide intermediate, dialdehyde starch aqueous solution, and cationic etherifying agent. The anionic polyacrylamide intermediate comprises the following raw materials: acrylamide, anionic monomer, molecular weight regulator, crosslinking monomer, initiator.

[0005] Further, the absolute dry mass ratio of the anionic polyacrylamide intermediate, dialdehyde starch aqueous solution, and cationic etherifying agent is (30 - 70):(20 - 60):(5 - 30);

[0006] The absolute dry mass ratio of the raw materials acrylamide, anionic monomer, molecular weight regulator, crosslinking monomer, and initiator of the anionic polyacrylamide intermediate is 100:(3 - 20):(0.1 - 3.0):(0.01 - 2.0):(0.05 - 1.5);

[0007] The mass ratio of dialdehyde starch to water in the dialdehyde starch aqueous solution is 1:2 - 5.

[0008] Further, the molecular weight regulator is selected from one or more of isopropanol, sodium hypophosphite, and sodium methallylsulfonate.

[0009] Further, the anionic monomer is selected from one or more of itaconic acid, (meth)acrylic acid, maleic acid (anhydride), fumaric acid (anhydride), 2-acrylamido-2-methylpropanesulfonic acid and their salts;

[0010] Further, the crosslinking monomer is selected from one or more combinations of methylene bisacrylamide, N,N-dimethylacrylamide, hydroxymethylacrylamide, 1,3,5-triacrylamido-hexahydrotriazine;

[0011] Further, the initiator is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, azodiisobutyramidine hydrochloride, azodiisopropylimidazoline hydrochloride, ammonium persulfate / sodium metabisulfite, sodium persulfate / sodium bisulfite.

[0012] Further, the aldehyde group content of the dialdehyde starch is 30% - 90%.

[0013] Further, the cationic etherifying agent is 3-chloro-2-hydroxypropyltrimethylammonium chloride.

[0014] A preparation method of the biodegradable high-solid-content enhanced water filter aid as described above, characterized by comprising the following steps:

[0015] S1. Prepare an anionic polyacrylamide intermediate: Add acrylamide, an anionic monomer, a molecular weight regulator, and a crosslinking monomer to a first reaction kettle according to an absolute dry mass ratio of 100:(3 - 20):(0.1 - 3.0):(0.01 - 2.0), add water to adjust the solid content to 20% - 40%, add a pH regulator to adjust the pH to 3 - 5, pass nitrogen, heat up to 60°C - 80°C, add an initiator for free radical polymerization reaction, control the reaction temperature between 80°C - 95°C, after reaching the expected viscosity, add a terminator, and cool down to 20°C - 40°C to obtain the anionic polyacrylamide intermediate;

[0016] S2. Prepare a dialdehyde starch aqueous solution: Add water and dialdehyde starch to a second reaction kettle according to a mass ratio of 2 - 5:1, heat up to 88°C - 95°C, keep warm for 10 - 30 min, and cool down to 20°C - 40°C to obtain the dialdehyde starch aqueous solution;

[0017] S3. Prepare a water filter aid enhancer: Add the dialdehyde starch aqueous solution prepared in S2 to the anionic polyacrylamide intermediate prepared in S1, add a pH regulator to adjust the pH to 8 - 10, add a cationic etherifying agent, control the reaction temperature at 25°C - 35°C, and simultaneously carry out crosslinking and etherification reactions for 1 - 3 hours. During the reaction process, add a pH regulator to maintain the pH at 8 - 10, and finally add a pH regulator to adjust the pH to 2 - 5, and add water to adjust the solid content to 20% - 30% to obtain the high-solid-content enhanced water filter aid.

[0018] Further, the terminator is selected from one or more of sodium sulfite, sodium bisulfite, sodium metabisulfite, and sodium ascorbate.

[0019] Further, the pH regulator includes an alkali and an acid. The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, and ammonia water; the acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, and citric acid.

[0020] Application of a biodegradable high-solid-content enhanced water filter agent as described above in papermaking.

[0021] The beneficial effects of the present invention are as follows: The biodegradable high-solid-content enhanced water filter agent prepared by the present invention has an anionic polyacrylamide chain as the head and a modified cationic dialdehyde starch as the tail. The anions and cations are alternately distributed and connected head to tail to form a micro-crosslinked structure. There are reactive groups such as amide groups, carboxyl groups, hydroxyl groups, and aldehyde groups on the molecular chain, which can form ionic bonds, chemical bonds, and hydrogen bonds with fibers, giving full play to the synergistic strengthening effect of polyacrylamide and dialdehyde starch, and overcoming the disadvantages of poor stability, easy gelation, and short storage period of GPAM-based strengthening agents. At the same time, when used in the wet end of paper, it can not only improve the dry strength and wet strength of paper, but also improve water filtration and retention, and can completely replace GPAM. Moreover, it is biodegradable and environmentally friendly. Specific Embodiments

[0022] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0023] An embodiment of the present invention provides a preparation method of a biodegradable high-solid-content enhanced water filter agent, including the following steps:

[0024] S1. Preparation of anionic polyacrylamide intermediate: Add acrylamide, anionic monomer, molecular weight regulator, and crosslinking monomer into the first reaction kettle according to the absolute dry mass ratio of 100:(3 - 20):(0.1 - 3.0):(0.01 - 2.0). Add water to adjust the solid content to 20% - 40%. Add a pH regulator to adjust the pH value to 3 - 5. Pass nitrogen and heat up to 60°C - 80°C. Add an initiator for free radical polymerization reaction. The absolute dry mass ratio of the initiator to acrylamide is 0.05 - 1.5:100. Control the reaction temperature between 80°C - 95°C. After reaching the expected viscosity, add a terminator and cool down to 20°C - 40°C to obtain the anionic polyacrylamide intermediate. Exemplarily, the absolute dry masses of acrylamide, anionic monomer, molecular weight regulator, and crosslinking monomer are 100:3:0.1:0.01; 100:5:1.0:0.5; 100:10:2.0:1.0; 100:15:2.5:1.5; 100:20:3.0:2.0; and the absolute dry mass ratio of the initiator to acrylamide is 0.05:100; 0.1:100; 0.5:100; 1.0:100; 1.5:100.

[0025] The molecular weight regulator is selected from one or more of isopropyl alcohol, sodium hypophosphite, and sodium methallylsulfonate.

[0026] The anionic monomer is selected from one or more of itaconic acid, (meth)acrylic acid, maleic acid (anhydride), fumaric acid (anhydride), 2 - acrylamido - 2 - methylpropanesulfonic acid, and their salts.

[0027] The crosslinking monomer is selected from one or more combinations of methylene bisacrylamide, N,N - dimethylacrylamide, hydroxymethylacrylamide, and 1,3,5 - triacrylamido - hexahydro - 1,3,5 - triazine.

[0028] The initiator is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, azodiisobutyramidine hydrochloride, azodiisopropylimidazoline hydrochloride, ammonium persulfate / sodium metabisulfite, and sodium persulfate / sodium bisulfite.

[0029] The terminator is selected from one or more of sodium sulfite, sodium bisulfite, sodium metabisulfite, and sodium ascorbate.

[0030] S2. Preparation of dialdehyde starch aqueous solution: Water and dialdehyde starch are added to the second reaction kettle according to a mass ratio of 2-5:1, heated to 88°C - 95°C, kept warm for 10 - 30 min, and then cooled to 20°C - 40°C to obtain the dialdehyde starch aqueous solution; the aldehyde group content of the dialdehyde starch is 30% - 90%. Exemplarily, the mass ratio of water to dialdehyde starch in the dialdehyde starch aqueous solution is 2:1; 3:1; 4:1; 5:1. The aldehyde group content of the dialdehyde starch is 30%, 40%, 50%, 60%, 70%, 80%, 90%.

[0031] S3. Preparation of drainage enhancer: The dialdehyde starch aqueous solution prepared in S2 is added to the anionic polyacrylamide intermediate prepared in S1, and a pH regulator is added to adjust the pH value to 8 - 10. A cationic etherifying agent is added, and the cationic etherifying agent is 3-chloro-2-hydroxypropyl trimethyl ammonium chloride. The reaction temperature is controlled at 25°C - 35°C, and the crosslinking and etherification reactions are carried out simultaneously for 1 - 3 hours. During the reaction process, a pH regulator is added to maintain the pH value at 8 - 10. Finally, a pH regulator is added to adjust the pH value to 2 - 5, and water is added to adjust the solid content to 20% - 30%, thus obtaining a high-solid-content enhanced drainage agent.

[0032] The pH regulator includes an alkali and an acid. The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, and ammonia water; the acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, and citric acid.

[0033] The absolute dry mass ratio of the anionic polyacrylamide intermediate, the dialdehyde starch aqueous solution, and the cationic etherifying agent is (30 - 70):(20 - 60):(5 - 30). Exemplarily, the absolute dry mass ratio of the anionic polyacrylamide intermediate, the dialdehyde starch aqueous solution, and the cationic etherifying agent is 30:20:5; 40:20:5; 50:60:5; 60:20:20; 70:50:30; 30:40:15; 70:60:30.

[0034] Examples

[0035] The following further elaborates on the present invention with specific examples. It should be understood that these examples are used to illustrate the basic principles, main features, and advantages of the present invention, and the present invention is not limited by the following examples. The implementation conditions adopted in the examples can be further adjusted according to specific requirements, and the implementation conditions not specified are usually those in conventional experiments. Additionally, unless otherwise specified, the dosages of components are in mass parts and mass %, and the viscosity values are measured at 25°C.

[0036] This example provides a preparation method of a biodegradable high-solid-content enhanced drainage agent. The main raw materials used and their feeding amounts are shown in the following table:

[0037] S1. Preparation of Anionic Polyacrylamide Intermediate

[0038] Table 1. Raw Material Ratio Table of Anionic Polyacrylamide Intermediate

[0039]

[0040] The specific implementation steps are as follows:

[0041] Add 100 parts of deionized water to the first reaction kettle equipped with a stirrer, a thermometer and a reflux condenser. Start stirring, add 200 parts of acrylamide with a content of 50%, 10 parts of acrylic acid, 1.2 parts of isopropyl alcohol, and 0.15 parts of methylene bisacrylamide. Stir, adjust the pH value to 4.0 with sodium hydroxide, pass nitrogen, heat up to 70°C, add 10.2 parts of ammonium persulfate aqueous solution as the initiator, turn on the cooling water to cool down, and control the reaction temperature between 80°C and 95°C. When the viscosity reaches 2000 mP.s (measured at 25°C), add 2 parts of anhydrous sodium sulfite as the terminator, and turn on the cooling water to cool down to 30°C to obtain 323 parts of an anionic polyacrylamide intermediate with a content of 35.0%.

[0042] S2. Preparation of Dialdehyde Starch Aqueous Solution

[0043] Table 2. Raw Material Ratio Table of Dialdehyde Starch Aqueous Solution

[0044] Raw materials Name Dosage (parts) Water Deionized water 195 Dialdehyde starch Dialdehyde starch with 40% aldehyde group content 65

[0045] The specific implementation is as follows:

[0046] Add 195 parts of deionized water and 65 parts of dialdehyde starch with an aldehyde group content of 40% to the second reaction kettle, stir, heat up to 90°C, keep warm for 20 min, and then cool down to 30°C to obtain a dialdehyde starch aqueous solution.

[0047] S3. Preparation of Drainage Aid

[0048] Table 3. Raw Material Ratio Table of Drainage Aid

[0049] Raw materials Name Dosage (parts) S1 Anionic polyacrylamide intermediate 323 S2 Dialdehyde starch aqueous solution 260 Base Sodium hydroxide aqueous solution (10%) 30 Cationic etherifying agent 3-chloro-2-hydroxypropyltrimethylammonium chloride 20 Acid 10% dilute sulfuric acid 8 Solid content adjusting water Deionized water 5

[0050] The specific implementation of the method is as follows:

[0051] Add the dialdehyde starch aqueous solution prepared in S2 to the anionic polyacrylamide intermediate prepared in S1, adjust the pH value to 9.8 with alkali, add 20 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride with a content of 69%, and carry out cross-linking and etherification reactions simultaneously at 25°C to 35°C for 2.5 hours. During the reaction, add alkali to maintain the pH value between 8 and 10. Finally, adjust the pH value to 3.2 with acid, and add 5 parts of deionized water to obtain 646 parts of a drainage aid with a solid content of 30%.

[0052] Example 2

[0053] This example provides a preparation method of a biodegradable high-solid-content enhanced water filter agent. The main raw materials used and their feeding amounts are shown in the following table:

[0054] S1. Preparation of anionic polyacrylamide intermediate

[0055] Table 4. Raw material ratio table of anionic polyacrylamide intermediate

[0056]

[0057] The specific implementation of the method is as follows:

[0058] Add 100 parts of deionized water to the first reaction kettle equipped with a stirrer, a thermometer and a reflux condenser. Start stirring, add 250 parts of acrylamide with a content of 50%, 8 parts of itaconic acid, 6 parts of acrylic acid, 0.9 part of sodium methallylsulfonate, and 1.0 part of N,N-dimethylacrylamide. Stir, adjust the pH value to 3.5 with potassium hydroxide, pass nitrogen, raise the temperature to 60°C, add 10.3 parts of an aqueous solution of initiator sodium persulfate and 7.5 parts of an aqueous solution of initiator sodium bisulfite. Turn on the cooling water to cool down, and control the reaction temperature between 80°C and 95°C. When the viscosity reaches 3000 mP.s (measured at 25°C), add 1.5 parts of terminator sodium metabisulfite, and turn on the cooling water to cool down to 25°C to obtain 385 parts of an anionic polyacrylamide intermediate with a content of 37.0%.

[0059] S2. Preparation of dialdehyde starch aqueous solution

[0060] Table 5. Raw material ratio table of dialdehyde starch aqueous solution

[0061] Raw materials Name Dosage (parts) Water Deionized water 385 Dialdehyde starch Dialdehyde starch with 70% aldehyde group content 96

[0062] The specific implementation of the method is as follows:

[0063] Add 385 parts of deionized water and 96 parts of dialdehyde starch with an aldehyde group content of 70% to the second reaction kettle, stir, raise the temperature to 93°C, keep warm for 15 minutes, and then cool down to 25°C to obtain a dialdehyde starch aqueous solution.

[0064] S3. Preparation of water filtration enhancer

[0065] Table 6. Raw material ratio table of water filtration enhancer

[0066] Raw materials Name Dosage (parts) S1 Anionic polyacrylamide intermediate 385 S2 Dialdehyde starch aqueous solution 481 Base Potassium hydroxide aqueous solution (10%) 42 Cationic etherifying agent 3-chloro-2-hydroxypropyltrimethylammonium chloride 35 Acid 10% dilute sulfuric acid 13 Solid content adjusting water Deionized water 120

[0067] The specific implementation of the method is as follows:

[0068] Add the dialdehyde starch aqueous solution prepared in S2 to the anionic polyacrylamide intermediate prepared in S1, adjust the pH value to 10.0 with alkali, add 35 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride with a content of 69%, and carry out crosslinking and etherification reactions simultaneously at 25 °C to 35 °C for 2.0 hours. During the reaction process, add alkali to maintain the pH value at 8-10. Finally, add acid to adjust the pH value to 2.8, and add 120 parts of deionized water to obtain 1076 parts of an enhanced filter aid with a solid content of 24.9%.

[0069] Example 3

[0070] This example provides a preparation method of a biodegradable high-solid-content enhanced filter aid. The main raw materials used and the feeding amounts are shown in the following table:

[0071] S1. Preparation of anionic polyacrylamide intermediate

[0072] Table 7. Raw material ratio table of anionic polyacrylamide intermediate

[0073]

[0074]

[0075] The specific implementation of the method is as follows:

[0076] Add 100 parts of deionized water to the first reaction kettle equipped with a stirrer, thermometer and reflux condenser. Start stirring, add 180 parts of acrylamide with a content of 50%, 2 parts of itaconic acid, 2 parts of maleic anhydride, 0.5 part of sodium hypophosphite, 0.3 part of sodium methallylsulfonate, and 0.04 part of 1,3,5-triacrylamido-hexahydrotriazine. Stir, adjust the pH value to 4.5 with ammonia water, pass nitrogen, heat up to 75 °C, add 10.5 parts of the initiator azodiisobutyramidine hydrochloride aqueous solution, turn on the cooling water to cool down, and control the reaction temperature between 80 °C and 95 °C. When the viscosity reaches 3500 mP.s (measured at 25 °C), add 1 part of the terminator sodium ascorbate, and turn on the cooling water to cool down to 25 °C to obtain 301 parts of an anionic polyacrylamide intermediate with a content of 34.0%.

[0077] S2. Preparation of dialdehyde starch aqueous solution

[0078] Table 8. Raw material ratio table of dialdehyde starch aqueous solution

[0079] Raw materials Name Dosage (parts) Water Deionized water 228 Dialdehyde starch Dialdehyde starch with 90% aldehyde group content 57

[0080] The specific implementation of the method is as follows:

[0081] Add 228 parts of deionized water and 57 parts of dialdehyde starch with an aldehyde group content of 90% to the second reaction kettle, stir, heat up to 95 °C, keep warm for 10 min, and then cool down to 25 °C to obtain an aqueous solution of dialdehyde starch.

[0082] S3. Preparation of drainage aid

[0083] Table 9. Raw material ratio table of drainage aid

[0084] Raw materials Name Dosage (parts) S1 Anionic polyacrylamide intermediate 301 S2 Dialdehyde starch aqueous solution 285 Base Sodium hydroxide aqueous solution (10%) 26 Cationic etherifying agent 3-chloro-2-hydroxypropyltrimethylammonium chloride 17 Acid 10% dilute sulfuric acid 7 Solid content adjusting water Deionized water 200

[0085] The specific implementation of the method is as follows:

[0086] Add the aqueous solution of dialdehyde starch prepared in S2 to the anionic polyacrylamide intermediate prepared in S1, adjust the pH value to 9.0 with alkali, add 17 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride with a content of 69%, and carry out crosslinking and etherification reactions simultaneously at 25 °C - 35 °C for 1 - 3 hours. During the reaction process, add alkali to maintain the pH value at 8 - 10, and finally add acid to adjust the pH value to 3.5, and add 200 parts of deionized water to obtain a drainage aid with a solid content of 20.1%.

[0087] Compare the storage stability of the above Examples 1 - 3 with commercially available GPAM products, as shown in Table 10.

[0088] Table 10. Storage stability of Examples 1 - 3 and commercially available GPAM products at 35 °C

[0089]

[0090] It can be seen from Table 10 that at 35 °C, the viscosity of commercially available GPAM increases from the initial viscosity of 22 mPa·s to 58 mPa·s after being placed for 10 days, and gels after 20 days, while the viscosity change of the drainage aid prepared in Examples 1 - 3 of the present invention is very small at 10 days, and no gel phenomenon occurs within 90 days.

[0091] Application Example 1

[0092] Evaluate the application of the drainage aid prepared in the above Examples 1 - 3, compare with commercially available GPAM products, with an addition amount of 1.5 kg / t paper on an absolutely dry basis, and test the paper strength performance, drainage and ash retention.

[0093] The pulp used for sheet forming is hardwood pulp and softwood pulp, with a mass percentage of 85:15, mixed and beaten, and the beating degree is 38 °SR. Dilute the pulp concentration to 1.0% (mass percentage) with tap water, the filler addition amount is 25%, and use a KRK2542 - A type semi-automatic paper sheet former (KRK Company, Japan) to form a circular paper sheet with a thickness of 0.03 m 2 and a basis weight of 90 g / m 2, the tensile index, bursting index and internal bond strength of the test paper samples, drainage (Canadian freeness meter) and first-pass retention rate were tested, and the data are shown in Tables 11 and 12.

[0094] Table 11. Test Results of Paper Physical Properties

[0095]

[0096] As can be seen from Table 11, at the same dosage, the dry tensile index, bursting strength and internal bond strength of the enhanced drainage agent products prepared in Examples 1-3 of the present invention are all superior to those of the commercially available GPAM, and the wet tensile index is close.

[0097] Table 12. Drainage and First-Pass Retention Rate

[0098] Sample number Blank Control example Example 1 Example 2 Example 3 Filtered water (ml) 380 455 475 480 470 First retention rate (%) 83 90 92 91 93

[0099] As can be seen from Table 12, for the high-solid-content enhanced drainage agent products prepared in Examples 1-3 of the present invention, the drainage rate is significantly faster than that of the commercially available GPAM, and the first-pass retention rate is also higher than that of the commercially available GPAM.

[0100] Application Example 2

[0101] The above-mentioned examples were subjected to application evaluation, compared with the commercially available GPAM products, and the paper strength performance, drainage and ash retention were tested.

[0102] The pulp used for sheet forming was self-made OCC pulp with a beating degree of 35°SR. The pulp concentration was diluted to 1.0% (mass percentage) with tap water, and circular paper sheets with a thickness of 0.03 m 2 were formed using a KRK2542-A semi-automatic paper sheet former (KRK Corporation, Japan), and the basis weight of the paper was 100 g / m 2 . The ring crush index, bursting index and internal bond strength of the test paper samples, drainage (Canadian freeness meter) and first-pass retention rate were tested, and the data are shown in Tables 13 and 14.

[0103] Table 13. Test Results of Paper Physical Properties

[0104]

[0105] As can be seen from Table 13, at the same dosage, the ring crush index, bursting index and internal bond strength of the enhanced drainage agent products prepared in Examples 1-3 of the present invention are all superior to those of the commercially available GPAM.

[0106] Table 14. Drainage and First-Pass Retention Rate

[0107]

[0108] As can be seen from Table 14, for the enhanced water filter products prepared in Examples 1 to 3 of the present invention, their water filtration rates are significantly faster than those of the commercially available GPAM, and the first-pass retention rates are also higher than those of the commercially available GPAM.

[0109] The above embodiments are only used to illustrate the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. However, the protection scope of the present invention cannot be limited thereby. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A biodegradable high-solid-content enhanced water filter agent, characterized in that, It includes the following raw materials: anionic polyacrylamide intermediate, dialdehyde starch aqueous solution and cationic etherifying agent, and the absolute dry mass ratio of the anionic polyacrylamide intermediate, dialdehyde starch aqueous solution and cationic etherifying agent is (30-70):(20-60):(5-30); The anionic polyacrylamide intermediate includes the following raw materials: acrylamide, anionic monomer, molecular weight regulator, crosslinking monomer and initiator; Among them, the preparation method of the biodegradable high-solid-content filter water enhancer includes the following steps: S1. Prepare an anionic polyacrylamide intermediate; S2. Prepare a dialdehyde starch aqueous solution; S3. Prepare a filter water enhancer: Add the dialdehyde starch aqueous solution prepared in S2 to the anionic polyacrylamide intermediate prepared in S1, add a pH regulator to adjust the pH to 8-10, add a cationic etherifying agent, control the reaction temperature at 25°C-35°C, and simultaneously carry out crosslinking and etherification reactions for 1-3 hours. During the reaction, add a pH regulator to maintain the pH at 8-10. Finally, add a pH regulator to adjust the pH to 2-5, and add water to adjust the solid content to 20%-30%, thus obtaining the high-solid-content filter water enhancer.

2. The biodegradable high-solid-content filter water enhancer according to claim 1, wherein The absolute dry mass ratio of acrylamide, anionic monomer, molecular weight regulator, crosslinking monomer and initiator in the anionic polyacrylamide intermediate is 100:(3-20):(0.1-3.0):(0.01-2.0):(0.05-1.5); The mass ratio of dialdehyde starch to water in the dialdehyde starch aqueous solution is 1:2-5.

3. The biodegradable high-solid-content enhanced water filter agent according to claim 1, characterized in that, The molecular weight regulator is selected from one or more of isopropyl alcohol, sodium hypophosphite, and sodium methallylsulfonate.

4. The biodegradable high-solid-content filter water enhancer according to claim 1, wherein The anionic monomer is selected from one or more of itaconic acid, (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, 2-acrylamido-2-methylpropanesulfonic acid and their salts; The crosslinking monomer is selected from one or more of methylene bisacrylamide, N,N-dimethylacrylamide, hydroxymethylacrylamide, 1,3,5-triacrylamido-hexahydrotriazine; The initiator is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, azodiisobutyramidine hydrochloride, azodiisopropylimidazoline hydrochloride, ammonium persulfate / sodium metabisulfite, and sodium persulfate / sodium bisulfite.

5. A biodegradable high-solid-content enhanced water filter agent according to claim 1, characterized in that, The aldehyde group content of the dialdehyde starch is 30%-90%.

6. The biodegradable high-solid content enhanced water filter agent according to claim 1, characterized in that, The cationic etherifying agent is 3-chloro-2-hydroxypropyltrimethylammonium chloride.

7. A biodegradable high-solid content enhanced water filter agent according to any one of claims 1-6, characterized in that, It includes the following steps: S1. Prepare an anionic polyacrylamide intermediate: Add acrylamide, anionic monomer, molecular weight regulator, and crosslinking monomer to the first reaction kettle, add water to adjust the solid content to 20%-40%, add a pH regulator to adjust the pH to 3-5, add an initiator for free radical polymerization reaction, and add a terminator to obtain the anionic polyacrylamide intermediate; S2. Preparation of dialdehyde starch aqueous solution: Water and dialdehyde starch are added to the second reaction kettle at a mass ratio of 2-5:1, heated to 88°C-95°C, kept warm for 10-30 min, and then cooled to 20°C-40°C to obtain the dialdehyde starch aqueous solution; S3. Preparation of drainage enhancer: The dialdehyde starch aqueous solution prepared in S2 is added to the anionic polyacrylamide intermediate prepared in S1, a pH regulator is added to adjust the pH value to 8-10, a cationic etherifying agent is added, and the reaction temperature is controlled at 25°C-35°C. At the same time, crosslinking and etherification reactions are carried out for 1-3 hours. During the reaction process, a pH regulator is added to maintain the pH value at 8-10. Finally, a pH regulator is added to adjust the pH value to 2-5, and water is added to adjust the solid content to 20%-30% to obtain a high-solid-content enhanced drainage agent.

8. A biodegradable high-solid-content enhanced water filter agent according to claim 7, characterized in that The terminator is selected from one or more of sodium sulfite, sodium bisulfite, sodium metabisulfite, and sodium ascorbate.

9. A biodegradable high-solid-content enhanced water filter agent according to claim 7, characterized in that, The pH regulator includes a base and an acid. The base is selected from one or more of sodium hydroxide, potassium hydroxide, and ammonia water; the acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, and citric acid.

10. Application of a biodegradable high-solid-content enhanced drainage agent according to any one of claims 1-9 in papermaking.

Images