Amido-containing main chain type polyquaternary ammonium salt as well as preparation method and application thereof
A main-chain polyquaternary ammonium salt with amide groups addresses the dewatering challenges in grass pulp papermaking by forming dense coagulation structures, enhancing dewatering efficiency and clarity.
Patent Information
- Application Number
- CN202510341556.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-07-15
AI Technical Summary
The high content of fine fibers and hemicellulose in straw pulp leads to poor water filtration, long water filtration time and low production efficiency. The existing retention filter aids have problems such as increasing viscosity and degradation of physical properties caused by insufficient cation density and large amount of use.
The main chain polyquaternary ammonium salt containing amide groups is used as the retention filter aid. By combining the quaternary ammonium group with the negative charge component in the straw slurry, the ammonium group interacts with the polar functional groups on the surface of the cellulose to form a dense floc, which improves the water filter performance and fiber retention rate.
Significantly shortens the dehydration time, reduces the slurry loss rate, improves the clearness of the filtrate, and enhances the water filtering performance and fiber retention rate of the straw slurry.
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Figure CN120309933A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fine chemicals, and particularly relates to a main-chain type polyquaternary ammonium salt containing an amide group, a preparation method thereof, and uses thereof. Background Art
[0002] Due to sustainable development, the dual-carbon goal, and the forest resources situation in China, there is an urgent need to develop straw pulp to replace wood pulp for papermaking and molded products. However, straw pulp has a high content of fine fibers and hemicellulose, and the produced pulp has problems such as poor drainage during papermaking and a large shrinkage rate of molded products. Moreover, due to poor drainage, the dehydration time of wet paper or wet embryos is long, resulting in low production efficiency.
[0003] Although many water-soluble polymers that can form hydrogen bonds with fibers can be used as retention and drainage aids, such as polyacrylamide, cationic polyacrylamide, etc. When using non-ionic and anionic polyacrylamide, alumina must be added, and the effect is good at a pH below 5; while macromolecules or polymers with cationic charges are more easily adsorbed by fibers with anionic charges and have obvious advantages. Currently, the most widely used high-molecular cationic retention and drainage aids in the paper industry include cationic starch, cationic cellulose, and cationic polyacrylamide, etc.
[0004] Existing research shows that increasing the addition amount of cationic polymers or the quaternary ammonium substitution degree can enhance the flocculation effect on pulp, and thereby improve the pulp retention rate and drainage performance; star-shaped and hyperbranched cationic polyacrylamides show more significant flocculation effects than traditional organic polymer flocculants due to their higher charge density. Therefore, increasing the cation density is crucial. However, the substitution degree of starch and cellulose is limited; cationic polyacrylamide generated by copolymerization of acrylamide and quaternary ammonium acrylate will release small molecule hydroxyalkyl quaternary ammonium salts due to ester bond hydrolysis and gradually lose its function as a cationic polymer; increasing the addition amount of cationic polymers (≥0.4 - 1%) often leads to an increase in system viscosity and uneven distribution of fine fiber particles, and the physical and mechanical properties of the products will thus decrease significantly.
[0005] Regarding cationic polymers characterized by a quaternary ammonium salt group, in addition to side-chain type polyquaternary ammonium salts, there are also main-chain type polyquaternary ammonium salts, including polyvinylamine-based cations directly quaternized from imine-type polymers and polyquaternary ammonium salts obtained by co-condensation quaternization of bifunctional monomers such as tetramethyl-1,3-propanediamine and dichloro-organics, which have characteristics such as large molecular weight, low skin absorption, high safety, high cation density, and good bactericidal activity. Therefore, this type of polyquaternary ammonium salt is widely used as a functional antibacterial disinfectant, mainly because the synthesized main-chain type polyquaternary ammonium salt has a relatively large dosage when used as a retention and drainage aid in pulp and paper making or does not show the advantage of high cation density. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a main-chain type polyquaternary ammonium salt containing an amide group, a preparation method thereof, and a use as a retention and drainage aid for straw pulp. Its quaternary ammonium groups are on the main chain, resistant to hydrolysis, with dense cations and high positive charge density, and combine with the negative charge components such as carboxylate anions (-COO - ) and oxygen anions (-O - ) carried by the straw pulp to trigger the formation of a dense floc structure; at the same time, borrowing the amide groups on its main chain and supplemented by non-ionic water-soluble polar groups, it interacts with the polar functional groups such as -OH and -O- on the surfaces of long fibers, fine fiber particles, hemicellulose, and residual lignin to associate and flocculate, and makes the formed flocs evenly distributed in the pulp, improving the water filtration performance and fiber retention rate of the straw pulp.
[0007] The technical problem to be solved by the present invention is achieved by the following technical solutions:
[0008] One of the purposes of the present invention is to provide a main-chain type polyquaternary ammonium salt containing an amide group, and its structural formula is as follows:
[0009]
[0010] Wherein, R1, R2, R3, and R4 are the same or different, and each independently selected from one of alkylene, arylene, alkylene aryl, heterocyclic alkylene, and alkyl heterocyclic alkylene; n1 and n2 are natural numbers.
[0011] Another purpose of the present invention is to provide a preparation method of the main-chain type polyquaternary ammonium salt containing an amide group, which is prepared by quaternization polycondensation of a diamine monomer, a dichloro monomer, and a dichloro monomer containing an amide group.
[0012] Another purpose of the present invention is to provide the use of the main-chain type polyquaternary ammonium salt containing an amide group as a retention and drainage aid for fiber pulp.
[0013] Another purpose of the present invention is to provide a retention and drainage aid for fiber pulp, comprising the main-chain type polyquaternary ammonium salt containing an amide group.
[0014] The beneficial effects of the present invention are: The present invention designs and synthesizes a main-chain type polyquaternary ammonium salt with a novel structure and uses it as a retention and drainage aid for fiber pulp dehydration. It can not only significantly shorten the dehydration time, but also improve the retention rate of fine fibers, reduce the pulp loss rate, and make the filtrate clear. Description of the Drawings
[0015] Figure 1 It is an infrared spectrogram of the main-chain type polyquaternary ammonium salt containing formamide group synthesized in Example 2. Detailed Embodiments
[0016] In order to make the technical means, creative features, achieved objectives and effects realized by the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments and illustrations.
[0017] The present invention provides a main-chain polyquaternary ammonium salt containing an amide group, and the structural formula is as follows:
[0018]
[0019] Wherein, R1, R2, R3, and R4 are the same or different and each independently selected from one of alkylene, arylene, alkylarylene, heterocyclene, and alkylheterocyclene; n1 and n2 are natural numbers.
[0020] Further, the alkylene is C1-C6 methylene.
[0021] Further, the arylene is phenylene.
[0022] Further, the alkylarylene is C1-C6 methylenephenyl.
[0023] Further, the heterocyclene is furylidene.
[0024] Further, the alkylheterocyclene is C1-C6 methylenefuryl.
[0025] Further, n1:n2≥1:9 and n1≠0.
[0026] Further, the molecular weight of the main-chain polyquaternary ammonium salt containing an amide group is 4000-20000.
[0027] The present invention also provides a preparation method of the main-chain polyquaternary ammonium salt containing an amide group, which is prepared by quaternization polycondensation reaction of a diamine monomer, a dichloro monomer and a dichloro monomer containing an amide group.
[0028] Further, the diamine monomer is selected from at least one of N,N,N′,N′-tetramethylethylenediamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, N,N,N′,N′-tetramethyl-1,4-butanediamine, N,N,N′,N′-tetramethyl-1,5-pentanediamine, N,N,N′,N′-tetramethyl-1,6-hexanediamine, N,N,N′,N′-tetramethyl-p-phenylenediamine and N,N,N′,N′-tetramethyl-2,5-furandiamine, but not limited thereto.
[0029] Further, the dichloro monomer is selected from at least one of 1,2-dichloroethane, 1,2-dichloropropane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,4-bis(chloromethyl)benzene, 1,3-bis(chloromethyl)benzene, but not limited thereto.
[0030] Further, the dichloro monomer containing an amide group is selected from at least one of bis(chloroacetyl)ethylenediamine, bis(chloromethylbenzoyl)ethylenediamine, and bis(chloromethylenefuroyl)ethylenediamine, but is not limited thereto. Specifically, the bis(chloroacetyl)ethylenediamine is prepared by reacting chloroacetyl chloride with ethylenediamine; the bis(chloromethylbenzoyl)ethylenediamine is prepared by reacting 4-chloromethylbenzoyl chloride with ethylenediamine; and the bis(chloromethylenefuroyl)ethylenediamine is prepared by reacting 5-chloromethylfuroyl chloride with ethylenediamine.
[0031] The present invention provides the use of the amide group-containing main-chain polyquaternary ammonium salt as a retention and drainage aid for fiber pulp. Specifically, the fiber pulp includes pulp containing fibers such as straw pulp, wood pulp, bamboo pulp, sugarcane pulp, and papermaking white water.
[0032] The present invention also provides a retention and drainage aid for fiber pulp, which comprises the amide group-containing main-chain polyquaternary ammonium salt.
[0033] Further, based on 100 kg of the dry weight of the fiber pulp, the dosage of the amide group-containing main-chain polyquaternary ammonium salt is 0.001 - 0.1 kg, preferably 0.01 - 0.05 kg.
[0034] Further, the retention and drainage aid for fiber pulp further comprises porous solid particles. Specifically, porous solid particles known in the art that have an adsorbing property for fibers can be used.
[0035] In some specific embodiments, the porous solid particles include but are not limited to at least one of diatomaceous earth, attapulgite, bentonite, nanocellulose, and porous chitosan.
[0036] Example 1
[0037] 1. Synthesis of the main-chain polyquaternary ammonium salt containing a formamide group:
[0038] 1.1 Synthesis of bis(chloroacetyl)ethylenediamine:
[0039] Ethyl acetate (80 mL) and chloroacetyl chloride (49.7 g, 0.44 mol) were added to a reaction flask, and then a mixed solution prepared from ethylenediamine (12.02 g, 0.2 mol), triethylamine (100 mL), and ethyl acetate (160 mL) was slowly added dropwise under stirring, controlling the temperature not to exceed 15°C. After the addition was completed, the temperature was raised to reflux for 90 min. After the reaction ended, the reaction solution was cooled to room temperature, then poured into ice water at 0°C, and a solid was precipitated. The solid was filtered, and the filter cake was washed with water three times and dried under vacuum to obtain bis(chloroacetyl)ethylenediamine with a yield of 96%.
[0040] 1.2 Synthesis of the main-chain polyquaternary ammonium salt containing a formamide group:
[0041] Add 1,2-dichloroethane (29.7 g, 0.3 mol), bis(chloroacetyl)ethylenediamine (63.9 g, 0.3 mol) and ethanol (250 mL) into a reaction flask. Subsequently, slowly add tetramethylpropylenediamine (78.14 g, 0.6 mol) dropwise under stirring. After the addition is complete, react at room temperature for 4 h, and then raise the temperature to 50 °C and react for 10 h. After the reaction is completed, cool the reaction solution to room temperature, then pour it into ethyl acetate, precipitate a solid, filter, and dry under vacuum to obtain a main-chain polyquaternary ammonium salt containing formamido group (hereinafter referred to as retention and drainage aid A), with a molecular weight of 7950 and a yield of 89%.
[0042] 2. Application of the main-chain polyquaternary ammonium salt containing formamido group
[0043] 2.1 Pulp preparation
[0044] Take the brown cellulose obtained by treating rice straw with SO3 mild heat explosion combined with dilute alkali (where cellulose is 61.5%, hemicellulose is 25.4%, and lignin is 7.3%), add water to adjust its solid content to 20 wt%, and grind it with a high-concentration grinder (grinding gap is 0.15 mm) to obtain a pulp with a beating degree of 70 °SR (hereinafter referred to as pulp A).
[0045] 2.2 Pulp dehydration
[0046] Add retention and drainage aid A (0.05% of the dry weight of pulp A) and pulp A (10 g) to water (190 mL) under stirring. After stirring for 15 min, filter by suction for 90 s to obtain a filter cake and filtrate. The wet weight of the filter cake is 10.06 g, the dry weight is 1.93 g, and the moisture content is 80.8 wt%; the loss rate of the pulp is 3.5%, which is 56.2% lower than that of the blank group without adding the retention and drainage aid; there is a small amount of precipitation at the bottom after the filtrate stands overnight, and the turbidity of the supernatant is 106.8.
[0047] Example 2
[0048] 1. Synthesis of the main-chain quaternary ammonium salt containing benzamido group
[0049] 1.1 Synthesis of bis(chloromethylbenzoyl)ethylenediamine
[0050] Add ethyl acetate (80 mL) and 4-chloromethylbenzoyl chloride (39.7 g, 0.21 mol) into a reaction flask. Subsequently, slowly add the mixed solution prepared from ethylenediamine (6.01 g, 0.1 mol), triethylamine (45 mL) and ethyl acetate (160 mL) dropwise under stirring, control the temperature not to exceed 25 °C, and after the addition is complete, raise the temperature to reflux and react for 90 min. After the reaction is completed, cool the reaction solution to room temperature, then pour it into ice water at 0 °C, precipitate a solid, filter by suction, wash the filter cake 3 times with water, and dry under vacuum to obtain bis(chloromethylbenzoyl)ethylenediamine, with a yield of 91%.
[0051] 1.2 Synthesis of Main-chain Polyquaternary Ammonium Salt Containing Benzamide Group
[0052] Add 1,3-dichloropropane (33.9 g, 0.3 mol), bis(chloromethylbenzoyl)ethylenediamine (109.5 g, 0.3 mol) and ethanol (300 mL) into a reaction flask. Then, slowly add tetramethylethylenediamine (69.72 g, 0.6 mol) dropwise under stirring. After the addition is completed, react at room temperature for 4 h, and then raise the temperature to 50 °C and react for 10 h. After the reaction is completed, cool the reaction solution to room temperature, then pour it into ethyl acetate to precipitate a solid. Filter and dry in vacuo to obtain a main-chain polyquaternary ammonium salt containing benzamide group (hereinafter referred to as retention and drainage aid B), with a molecular weight of 15300 and a yield of 97%.
[0053] 2. Application of Main-chain Polyquaternary Ammonium Salt Containing Benzamide Group
[0054] 2.1 Slurry Preparation
[0055] Take the brown cellulose obtained by treating rice straw with SO3 mild heat explosion combined with dilute alkali (where cellulose is 63.1%, hemicellulose is 26.2%, and lignin is 9.4%). Add water to adjust its solid content to 20 wt%, and grind it with a high-concentration grinder (grinding gap is 0.15 mm) to obtain a slurry with a beating degree of 63°SR (hereinafter referred to as slurry B).
[0056] 2.2 Slurry Dehydration
[0057] Add retention and drainage aid B (prepared into an aqueous solution with a concentration of 10 wt% by adding water, 5 mL) accounting for 0.05% of the dry weight of slurry B and slurry B (10 g) into water (190 mL) under stirring. Stir for 15 min and then filter by suction for 90 s to obtain a filter cake and filtrate. The wet weight of the filter cake is 9.43 g, the dry weight is 1.99 g, and the moisture content is 78.9 wt%; the loss rate of the slurry is 0.5%, which is 92.3% lower than that of the blank group without adding the retention and drainage aid; the filtrate is clear and the turbidity is 9.9.
[0058] Example 3
[0059] 1. Synthesis of Main-chain Quaternary Ammonium Salt Containing Furanformamide Group
[0060] 1.1 Synthesis of Bis(chloromethylfuranformyl)ethylenediamine
[0061] Ethyl acetate (80 mL) and 5-chloromethylfuroyl chloride (37.63 g, 0.21 mol) were added to a reaction flask. Subsequently, a mixed solution prepared from ethylenediamine (6.01 g, 0.1 mol), triethylamine (45 mL), and ethyl acetate (160 mL) was slowly added dropwise with stirring, controlling the temperature not to exceed 25 °C. After the addition was complete, the temperature was raised to reflux and the reaction was carried out for 90 min. After the reaction was completed, the reaction solution was cooled to room temperature, then poured into ice water at 0 °C, and a solid was precipitated. It was filtered by suction, the filter cake was washed with water 3 times, and dried under vacuum to obtain bis(chloromethylfuroyl)ethylenediamine with a yield of 85%.
[0062] 1.2 Synthesis of main-chain polyquaternary ammonium salt containing furoamide group
[0063] 1,3-Dichloropropane (61 g, 0.54 mol), bis(chloromethylfuroyl)ethylenediamine (20.71 g, 0.06 mol), and ethanol (300 mL) were added to a reaction flask. Subsequently, tetramethylpropylenediamine (78.14 g, 0.6 mol) was slowly added dropwise with stirring. After the addition was complete, the reaction was carried out at room temperature for 4 h, and then the temperature was raised to 50 °C and the reaction was carried out for 10 h. After the reaction was completed, the reaction solution was cooled to room temperature, then poured into ethyl acetate, and a solid was precipitated. It was filtered and dried under vacuum to obtain a main-chain polyquaternary ammonium salt containing furoamide group (hereinafter referred to as retention and drainage aid C) with a molecular weight of 4900 and a yield of 91%.
[0064] 2. Application of main-chain quaternary ammonium salt containing furoamide group
[0065] 2.1 Slurry preparation
[0066] Same as Example 1.
[0067] 2.2 Slurry dehydration
[0068] Retention and drainage aid C (0.05% of the dry weight of Slurry A) and Slurry A (10 g) were added to water (190 mL) with stirring. After stirring for 15 min, it was filtered by suction for 90 s to obtain a filter cake and filtrate. The wet weight of the filter cake was 9.02 g, the dry weight was 2.00 g, and the moisture content was 77.8 wt%; the loss rate of the slurry was 0; the filtrate was clear and the turbidity was 7.5.
[0069] Example 4
[0070] 1. Synthesis of main-chain quaternary ammonium salt containing benzamide group
[0071] 1.1 Synthesis of bis(chloromethylbenzoyl)ethylenediamine
[0072] Same as Example 1.
[0073] 1.2 Synthesis of main-chain polyquaternary ammonium salt containing benzamide group
[0074] Add 1,2-dichloroethane (50.47 g, 0.54 mol), bis(chloromethylbenzoyl)ethylenediamine (32.87 g, 0.09 mol) and ethanol (300 mL) into a reaction flask. Subsequently, slowly dropwise add tetramethylethylenediamine (72.05 g, 0.62 mol) under stirring. After the addition is complete, react at room temperature for 4 h, and then raise the temperature to 50 °C and react for 10 h. After the reaction is completed, cool the reaction solution to room temperature, then pour it into ethyl acetate, precipitate a solid, filter, and dry under vacuum to obtain a main-chain type polyquaternary ammonium salt containing benzamide group (hereinafter referred to as retention and drainage aid D), with a molecular weight of 15300 and a yield of 90.5%.
[0075] 2. Application of the main-chain type polyquaternary ammonium salt containing benzamide group
[0076] 2.1 Slurry preparation
[0077] Same as Example 1.
[0078] 2.2 Slurry dewatering
[0079] Under stirring, add retention and drainage aid D accounting for 0%, 0.01%, 0.03%, 0.05%, 0.1% of the dry weight of Slurry A and bentonite accounting for 0.35% of the dry weight of Slurry A into water (190 mL) respectively. After mixing evenly, add Slurry A (10 g). After stirring for 15 min, carry out suction filtration, and record the time until no liquid drops or the time to break the vacuum, which are 245 s, 146 s, 130 s, 117 s, 109 s and 97 s respectively. After calculation, the water filtration time of the slurry added with retention and drainage aid D is reduced by 40.4%, 46.9%, 52.2%, 55.5% and 60.4% respectively.
[0080] Comparative Example 1
[0081] 1. Slurry preparation
[0082] Same as Example 1.
[0083] 2. Slurry dewatering
[0084] Add Slurry A (10 g) into water (190 mL) under stirring. After stirring for 15 min, carry out suction filtration for 90 s to obtain a filter cake and filtrate. The wet weight of the filter cake is 14.02 g, the dry weight is 1.84 g, and the water content is 87.0 wt%; the slurry loss rate is 8%; there are precipitates in the filtrate after standing overnight, and the turbidity of the supernatant is 113.
[0085] Comparative Example 2
[0086] 1. Slurry preparation
[0087] Same as Example 2.
[0088] 2. Slurry dewatering
[0089] Add slurry B (10 g) to water (190 mL) under stirring. After stirring for 15 min, perform suction filtration for 90 s. After suction filtration, obtain a filter cake and filtrate. The wet weight of the filter cake is 12.25 g, the dry weight is 1.87 g, and the moisture content is 84.7 wt%; the slurry loss rate is 6.5%; after the filtrate stands overnight, precipitates are separated out, and the turbidity of the supernatant is 105.8.
[0090] As can be seen from the above examples and comparative examples, when the main-chain polyquaternary ammonium salt containing an amide group of the present invention is used as a retention and drainage aid in the dehydration treatment of fiber pulp, it can not only significantly shorten the dehydration time, reduce the slurry loss amount, but also make the filtrate clear.
[0091] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.
Claims
1. A main-chain polyquaternary ammonium salt containing an amide group, with the structural formula as follows: Among them, R1, R2, R3, and R4 are the same or different and each independently selected from one of alkylene, arylene, alkylene aryl, heterocyclic group, and alkylene heterocyclic group; n1 and n2 are natural numbers.
2. The main-chain type polyquaternary ammonium salt containing an amide group according to claim 1, characterized in that: The alkylene is C1-C6 methylene; Preferably, the arylene is phenylene; Preferably, the alkylene aryl is C1-C6 methylene phenyl; Preferably, the heterocyclic group is furyl; Preferably, the alkylene heterocyclic group is C1-C6 methylene furyl.
3. The main-chain type polyquaternary ammonium salt containing an amide group according to claim 1, characterized in that: n1:n2≥1:9, n1≠0.
4. The main-chain type polyquaternary ammonium salt containing an amide group according to claim 1, wherein: The molecular weight of the main-chain polyquaternary ammonium salt containing an amide group is 4000-20000.
5. A preparation method of a main-chain polyquaternary ammonium salt containing an amide group, which is prepared by quaternization polycondensation reaction of a diamine monomer, a dichloro monomer, and a dichloro monomer containing an amide group.
6. The preparation method according to claim 5, wherein: The diamine monomer is selected from at least one of N,N,N′,N′-tetramethylethylenediamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, N,N,N′,N′-tetramethyl-1,4-butanediamine, N,N,N′,N′-tetramethyl-1,5-pentanediamine, N,N,N′,N′-tetramethyl-1,6-hexanediamine, N,N,N′,N′-tetramethyl-p-phenylenediamine, and N,N,N′,N′-tetramethyl-2,5-furandimethanamine; Preferably, the dichloro monomer is selected from at least one of 1,2-dichloroethane, 1,2-dichloropropane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,4-bis(chloromethyl)benzene, and 1,3-bis(chloromethyl)benzene; Preferably, the dichloro monomer containing an amide group is selected from at least one of bis(chloroacetyl)ethylenediamine, bis(chloromethylbenzoyl)ethylenediamine, and bis(chloromethylene furanoyl)ethylenediamine.
7. Use of the main-chain polyquaternary ammonium salt containing an amide group according to any one of claims 1-4 or the main-chain polyquaternary ammonium salt containing an amide group prepared by the preparation method according to any one of claims 5-6 as a retention and drainage aid for fiber pulp.
8. A retention and drainage aid for fiber pulp, comprising the main-chain polyquaternary ammonium salt containing an amide group according to any one of claims 1-4 or the main-chain polyquaternary ammonium salt containing an amide group prepared by the preparation method according to any one of claims 5-6.
9. The retention and drainage aid for fiber pulp according to claim 8, characterized in that: Based on 100 kg of dry weight of fiber pulp, the dosage of the main-chain polyquaternary ammonium salt containing an amide group is 0.001-0.1 kg, preferably 0.01-0.05 kg.
10. The retention and drainage aid for fiber pulp according to claim 8, characterized in that: The retention and drainage aid for straw pulp further comprises porous solid particles; Preferably, the porous solid particles include but are not limited to at least one of diatomite, attapulgite, bentonite, nanocellulose, and porous chitosan.