Modified cationic polyacrylamide papermaking reinforcing agent and preparation method thereof

Abstract

The invention discloses a modified cationic polyacrylamide papermaking reinforcing agent and a preparation method thereof.The preparation method comprises the following steps that S1, acrylamide, a first cationic monomer, a second cationic monomer and deionized water are added into a reaction kettle, and a solution A is obtained; s2, adding a functional monomer, a polymerization inhibitor, acrylamide and deionized water into a monomer kettle to obtain a solution B; s3, respectively dissolving an oxidation initiator, a reduction initiator and an azo initiator with deionized water to obtain an initiation solution A, an initiation solution B and an initiation solution C; and S4, heating the solution A, introducing nitrogen for protection, then slowly dropwise adding the initiation solution A and the initiation solution B into the solution A, obtaining a mixed solution C after dropwise adding is completed, then slowly dropwise adding the solution B and the initiation solution C into the mixed solution C, after dropwise adding is completed, carrying out a heat preservation reaction for 1-3 h, cooling and discharging, and thus obtaining the product. The papermaking reinforcing agent has the advantages that the prepared papermaking reinforcing agent can remarkably enhance the strength of paper and has the function of a fixing agent.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical additives for papermaking, and particularly relates to a modified cationic polyacrylamide papermaking enhancer and a preparation method thereof. Background Art

[0002] Waste paper fibers are of poor quality. After repeated use and processing, their fiber length and strength typically decrease. This also increases impurity levels, impacting the paper's physical properties and generally resulting in lower strength. To improve the various physical strengths of paper, manufacturers have attempted to employ various physical methods (for example, selecting high-quality fiber raw materials, optimizing the pulping process, selecting appropriate papermaking parameters, maintaining paperboard thickness, and adjusting its moisture content). While these methods have achieved some improvement, they often come with a significant increase in production costs, placing significant financial pressure on manufacturers. Therefore, the addition of papermaking strengthening agents during the paperboard production process can effectively improve the physical strength of the finished paper. Representative examples include modified starch and modified polyacrylamide.

[0003] Modified starch is the most commonly used pulp strengthening agent in the papermaking industry. It can increase paper strength and improve paper surface properties. However, its usage is large and costly. Moreover, starch-based strengthening agents are generally powders, requiring investment in specialized equipment to gelatinize, dissolve, and dilute the starch. This not only increases equipment investment costs but also is inconvenient to use. Commonly used polyacrylamide strengthening agents are low-solids aqueous solutions of polyacrylamide linear polymers. When applied to low-quality pulps such as waste paper raw materials with short fibers, high levels of foreign cells, impurities, and anionic waste, their strengthening effect is not ideal. Therefore, it is necessary to moderately cross-link and modify them to improve their paper strengthening efficiency.

[0004] Furthermore, the closed whitewater circulation technology used in modern papermaking can lead to high levels of dissolved and colloidal substances (DCS) in the papermaking system, resulting in deposits that seriously impact product quality and paper machine operation. Using a fixative to neutralize the highly negatively charged DCS and fix it to the fibers, allowing it to be carried out of the paper machine's whitewater system as the paper is made, is the most common method for controlling DCS levels and deposition. Both strengthening and fixing agents are often used in the papermaking process. In other words, these two agents are separate products used independently in the papermaking process. Currently, no additives have been reported that function as both strengthening and fixing agents. Summary of the Invention

[0005] The present invention provides a modified cationic polyacrylamide papermaking strengthening agent and a preparation method thereof, aiming to overcome the above-mentioned deficiencies in the prior art.

[0006] The present invention solves the above technical problems with the following technical solution: A method for preparing a modified cationic polyacrylamide papermaking strengthening agent, comprising the following steps:

[0007] S1. Preparation of solution A: acrylamide, a cationic monomer, a cationic monomer and deionized water were added to the reaction vessel and stirred to obtain a solution A and set aside;

[0008] S2. Preparation of solution B: functional monomer, polymerization inhibitor, acrylamide and deionized water were added to the monomer kettle and stirred to obtain solution B and set aside;

[0009] S3 initiator solution preparation: The oxidation initiator, the reduction initiator and the azo initiator were dissolved in deionized water to obtain the corresponding initiator solution A, initiator solution B and initiator solution C, set aside;

[0010] S4. Initiation reaction: Heat solution A to 50-80°C and pass nitrogen protection, then slowly drop initiator liquid A and initiator liquid B into solution A at the same time, after the addition is complete, obtain mixed solution C, then slowly drop in solution B and initiator liquid C into mixed solution C at the same time, after the addition is complete, keep warm for 1-3 hours, cool and discharge, and obtain modified cationic polyacrylamide papermaking additive.

[0011] On the basis of the above technical solutions, the present invention can also make the following further specific options.

[0012] Specifically, the first cationic monomer is acryloyloxyethyltrimethylammonium chloride.

[0013] Specifically, the cationic monomer is any one or more of methacryloyloxyethyltrimethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, methacryloyloxypropyltrimethylammonium chloride, acryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride, acryloyloxypropyldimethylbenzylammonium chloride, methacryloyloxypropyldimethylbenzylammonium chloride, acrylamidopropyltrimethylammonium chloride, methacryloylpropyltrimethylammonium chloride, methacryloylethyltrimethylammonium chloride and diallyldimethylammonium chloride.

[0014] Specifically, the functional monomer is any one or more of glycidyl methacrylate, N,N'-methylenebisacrylamide, glutaraldehyde and sodium vinyl sulfonate.

[0015] Specifically, the polymerization inhibitor is any one or more of sodium formate, 2,4-diphenyl-4-methyl-1-pentene, isopropyl alcohol and dodecyl mercaptan.

[0016] Specifically, the oxidation initiator is any one or more of hydrogen peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, potassium persulfate and ammonium persulfate, and the concentration of the initiator solution A is 5-10 wt%.

[0017] Specifically, the reduction initiator is any one or more of anhydrous sodium sulfite, sodium bisulfite and sodium thiosulfate, and the concentration of the initiator solution B is 4-8 wt %.

[0018] Specifically, the azo initiator is any one or more of azobisisobutyronitrile, azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride, and the concentration of the initiator solution C is 3-5wt%.

[0019] Specifically, by weight, solution A of S1 contains 4-5 parts of acrylamide, 2-3 parts of cationic monomer 1, 8-10 parts of cationic monomer 2, and 58-62 parts of deionized water; solution B of S2 contains 0.05-0.06 parts of functional monomer, 0.04-0.05 parts of polymerization inhibitor, 0.1-0.2 parts of acrylamide, and 2-3 parts of deionized water; in S4, the amount of initiator liquid A and initiator liquid B is 1.5-2.4% of solution A, the amount of solution B is 3-5% of solution A, and the amount of initiator liquid C is 1-2% of solution A.

[0020] In addition, the present invention also provides a method for preparing a modified cationic polyacrylamide papermaking strengthening agent, which is prepared by the above method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adds functional monomers during the preparation of polyacrylamide to moderately crosslink and modify the original linear polyacrylamide to form a network structure. The modified polyacrylamide effectively combines with paper fibers to form more hydrogen bonds and form a crosslinked network structure as a whole, which more effectively inhibits the free movement of the fibers, thereby improving the strength of the paper. In addition, the moderately crosslinked modified polyacrylamide papermaking strengthening agent provided by the present invention has a large molecular weight and carries a certain positive charge after network crosslinking, can effectively adsorb anionic waste in the slurry, and plays the same role as a fixative. That is, the modified polyacrylamide provided by the present invention has the functions of both a strengthening agent and a fixative, and the use of a fixative can be reduced or omitted during production, resulting in a simpler process and lower costs. DETAILED DESCRIPTION

[0023] The technical solutions provided by the present invention are described clearly and completely below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0024] To avoid redundancy, the raw materials used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0025] Example 1

[0026] A modified cationic polyacrylamide papermaking strengthening agent, the preparation process of which is as follows: all raw materials are calculated in equal parts by weight,

[0027] S1. Preparation of solution A: 4 parts of acrylamide, 2 parts of acryloyloxyethyl trimethylammonium chloride, 8 parts of methacryloyloxyethyl trimethylammonium chloride and 60 parts of deionized water were added to the reaction vessel and stirred to obtain solution A and set aside;

[0028] S2. Preparation of solution B: 0.05 parts of glycidyl methacrylate, 0.04 parts of sodium formate and 3 parts of deionized water were added to the monomer kettle and stirred to obtain a solution B and set aside;

[0029] S3 initiator solution preparation: Take 0.1 parts of sodium persulfate, 0.08 parts of sodium bisulfite and 0.04 parts of azobisisobutylamidine hydrochloride, respectively, into three containers, each container was added 1 part of deionized water, after dissolution, to obtain initiator solution A, initiator solution B and initiator solution C, set aside;

[0030] S4. Initiation reaction: Heat solution A to 55°C and pass nitrogen protection, then slowly drop all the above-mentioned initiator liquid A and initiator liquid B to be used into solution A at the same time, after the addition is complete, a mixed solution C is obtained, then slowly drop all the solution B and initiator liquid C to be used to the mixed solution C at the same time, after the addition is complete, keep the temperature for reaction for 1 hour, cool and discharge, and obtain the modified cationic polyacrylamide papermaking additive.

[0031] Example 2

[0032] A modified cationic polyacrylamide papermaking strengthening agent, the preparation process of which is as follows: all raw materials are calculated in equal parts by weight,

[0033] S1. Preparation of Solution A: 4 parts of acrylamide, 2 parts of acryloyloxyethyl trimethylammonium chloride, 4 parts of methacryloyloxyethyl trimethylammonium chloride, 4 parts of methacryloyloxypropyl trimethylammonium chloride and 60 parts of deionized water were added to the reaction kettle and stirred to obtain Solution A and set aside;

[0034] S2. Preparation of solution B: 0.05 parts of glycidyl methacrylate, 0.04 parts of sodium formate and 3 parts of deionized water were added to the monomer kettle and stirred to obtain a solution B and set aside;

[0035] S3 initiator solution preparation: Take 0.1 parts of sodium persulfate, 0.08 parts of sodium bisulfite and 0.04 parts of azobisisobutylamidine hydrochloride, respectively, into three containers, each container was added 1 part of deionized water, after dissolution, to obtain initiator solution A, initiator solution B and initiator solution C, set aside;

[0036] S4. Initiation reaction: Heat solution A to 60°C and pass nitrogen protection, then slowly drop all the above-mentioned initiator liquid A and initiator liquid B to be used into solution A at the same time, after the addition is complete, a mixed solution C is obtained, then slowly drop all the solution B and initiator liquid C to be used to the mixed solution C at the same time, after the addition is complete, keep the temperature for reaction for 1 hour, cool and discharge, and obtain the modified cationic polyacrylamide papermaking additive.

[0037] Example 3

[0038] A modified cationic polyacrylamide papermaking strengthening agent, the preparation process of which is as follows: all raw materials are calculated in equal parts by weight,

[0039] S1. Preparation of solution A: 4 parts of acrylamide, 2 parts of acryloyloxyethyl trimethylammonium chloride, 8 parts of acrylamidopropyl trimethylammonium chloride and 60 parts of deionized water were added to the reaction vessel and stirred to obtain solution A and set aside;

[0040] S2. Preparation of solution B: 0.05 parts of glycidyl methacrylate, 0.04 parts of sodium formate and 3 parts of deionized water were added to the monomer kettle and stirred to obtain a solution B and set aside;

[0041] S3 initiator solution preparation: Take 0.1 parts of ammonium persulfate, 0.08 parts of sodium bisulfite and 0.04 parts of azobisisobutylamidine hydrochloride, respectively, into three containers, each container was added 1 part of deionized water, after dissolution, to obtain initiator solution A, initiator solution B and initiator solution C, set aside;

[0042] S4. Initiation reaction: Heat solution A to 65°C and pass nitrogen protection, then slowly drop all the above-mentioned initiator liquid A and initiator liquid B to be used into solution A at the same time, after the addition is complete, a mixed solution C is obtained, then slowly drop all the solution B and initiator liquid C to be used to the mixed solution C at the same time, after the addition is complete, keep the temperature for reaction for 1 hour, cool and discharge, and obtain the modified cationic polyacrylamide papermaking additive.

[0043] Example 4

[0044] A modified cationic polyacrylamide papermaking strengthening agent, the preparation process of which is as follows: all raw materials are calculated in equal parts by weight,

[0045] S1. Preparation of solution A: 4 parts of acrylamide, 2 parts of acryloyloxyethyl trimethylammonium chloride, 2 parts of methacryloyloxyethyl trimethylammonium chloride, 6 parts of acryloyloxyethyl dimethylbenzyl ammonium chloride and 60 parts of deionized water were added to the reaction kettle and stirred to obtain solution A and set aside;

[0046] S2. Preparation of solution B: 0.05 parts of N,N- methylenebisacrylamide, 0.04 parts of sodium formate and 3 parts of deionized water were added to the monomer kettle and stirred to obtain a solution B and set aside;

[0047] S3 initiator solution preparation: Take 0.1 parts of sodium persulfate, 0.08 parts of sodium bisulfite and 0.04 parts of azobisisobutylamidine hydrochloride, respectively, into three containers, each container was added 1 part of deionized water, after dissolution, to obtain initiator solution A, initiator solution B and initiator solution C, set aside;

[0048] S4. Initiation reaction: Heat solution A to 65°C and pass nitrogen protection, then slowly drop all the above-mentioned initiator liquid A and initiator liquid B to be used into solution A at the same time, after the addition is complete, a mixed solution C is obtained, then slowly drop all the solution B and initiator liquid C to be used to the mixed solution C at the same time, after the addition is complete, keep the temperature for reaction for 1 hour, cool and discharge, and obtain the modified cationic polyacrylamide papermaking additive.

[0049] Example 5

[0050] A modified cationic polyacrylamide papermaking strengthening agent, the preparation process of which is as follows: all raw materials are calculated in equal parts by weight,

[0051] S1. Preparation of solution A: 4 parts of acrylamide, 2 parts of acryloyloxyethyl trimethylammonium chloride, 8 parts of methacryloyloxyethyl trimethylammonium chloride and 60 parts of deionized water were added to the reaction vessel and stirred to obtain solution A and set aside;

[0052] S2. Preparation of solution B: 0.02 parts of glycidyl methacrylate, 0.03 parts of N,N- methylenebisacrylamide, 0.04 parts of sodium formate and 3 parts of deionized water were added to the monomer kettle and stirred to obtain a solution B and set aside;

[0053] S3 initiator solution preparation: Take 0.1 parts of sodium persulfate, 0.08 parts of sodium bisulfite and 0.04 parts of azobisisobutylamidine hydrochloride, respectively, into three containers, each container was added 1 part of deionized water, after dissolution, to obtain initiator solution A, initiator solution B and initiator solution C, set aside;

[0054] S4. Initiation reaction: Heat solution A to 60°C and pass nitrogen protection, then slowly drop all the above-mentioned initiator liquid A and initiator liquid B to be used into solution A at the same time, after the addition is complete, a mixed solution C is obtained, then slowly drop all the solution B and initiator liquid C to be used to the mixed solution C at the same time, after the addition is complete, keep the temperature for reaction for 1 hour, cool and discharge, and obtain the modified cationic polyacrylamide papermaking additive.

[0055] Test Case

[0056] The performance of the paper strengthening agents prepared in Examples 1-5 of the present invention was tested as follows:

[0057] 1. Experimental pulp: The pulp was prepared from waste paper raw materials, and no chemicals were added to the pulp.

[0058] 2. Experimental drugs:

[0059] ① The enhancer product prepared in Examples 1 to 5;

[0060] ② Comparative Examples 1 to 3 are commercially available paper enhancer products (specifically, Comparative Example 1 is an imported paper enhancer from a foreign company A, Comparative Example 2 is a paper enhancer from a foreign company B, and Comparative Example 3 is a domestically produced paper enhancer).

[0061] 3. Experimental Procedure: After diluting the reinforcing agent 100-fold with water, the paper was then added to the corresponding experimental pulp sample and cut into sheets using a paper sampler. Appropriate pulp was prepared with 150 ppm of retention and drainage aid, 15 kg / ton of dry strength agent, and 2 kg / ton of reinforcing agent. The pulp was dried at 120°C for 15 minutes and then equilibrated in a constant temperature chamber for 12 hours. Blank experiments were performed using 150 ppm of retention and drainage aid and 30 kg / ton of dry strength agent. Physical properties of the finished paper are shown in Table 1.

[0062] The white water turbidity reduction experiment demonstrated that the enhancer can capture anionic waste. Specific experimental steps: The white water supernatant under the net was centrifuged at 2000 rpm for 15 minutes to quickly remove fine components. The supernatant was collected as DCS water and the turbidity of the DCS water was then measured.

[0063] Table 1 Comparison of physical indicators of paper produced by the enhancer laboratory

[0064]

[0065] As can be seen from the above table, the addition of the reinforcing agent prepared in Examples 1-5 of the present invention can significantly improve the dry tensile strength, bursting resistance and ring crush strength of the pulp, and it plays a certain role as a fixative, which can absorb anionic garbage in the pulp and significantly reduce the turbidity of the white water.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a modified cationic polyacrylamide papermaking strengthening agent, characterized in that: The steps include: S1. Preparation of solution A: acrylamide, a cationic monomer, a cationic monomer and deionized water were added to the reaction vessel and stirred to obtain a solution A and set aside; S2. Preparation of solution B: functional monomer, polymerization inhibitor, acrylamide and deionized water were added to the monomer kettle and stirred to obtain solution B and set aside; S3 initiator solution preparation: The oxidation initiator, the reduction initiator and the azo initiator were dissolved in deionized water to obtain the corresponding initiator solution A, initiator solution B and initiator solution C, set aside; S4. Initiation reaction: Heat solution A to 50-80°C and pass nitrogen protection, then slowly drop initiator liquid A and initiator liquid B into solution A at the same time, after the addition is complete, obtain mixed solution C, then slowly drop in solution B and initiator liquid C into mixed solution C at the same time, after the addition is complete, keep warm for 1-3 hours, cool and discharge, and obtain modified cationic polyacrylamide papermaking additive.

2. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The first cationic monomer is acryloyloxyethyltrimethylammonium chloride.

3. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The cationic monomer is any one or more of methacryloyloxyethyltrimethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, methacryloyloxypropyltrimethylammonium chloride, acryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride, acryloyloxypropyldimethylbenzylammonium chloride, methacryloyloxypropyldimethylbenzylammonium chloride, acrylamidopropyltrimethylammonium chloride, methacryloylpropyltrimethylammonium chloride, methacryloylethyltrimethylammonium chloride and diallyldimethylammonium chloride.

4. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The functional monomer is any one or more of glycidyl methacrylate, N,N'-methylenebisacrylamide, glutaraldehyde and sodium vinyl sulfonate.

5. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The polymerization inhibitor is any one or more of sodium formate, 2,4-diphenyl-4-methyl-1-pentene, isopropyl alcohol and dodecyl mercaptan.

6. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The oxidation initiator is any one or more of hydrogen peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, sodium persulfate, potassium persulfate and ammonium persulfate, and the concentration of the initiator solution A is 5-10 wt %.

7. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The reduction initiator is any one or more of anhydrous sodium sulfite, sodium bisulfite and sodium thiosulfate, and the concentration of the initiator solution B is 4-8 wt %.

8. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to claim 1, characterized in that: The azo initiator is any one or more of azobisisobutyronitrile, azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride, and the concentration of the initiator solution C is 3-5wt%.

9. The method for preparing a modified cationic polyacrylamide papermaking strengthening agent according to any one of claims 1 to 8, characterized in that: In parts by weight, solution A of S1 contains 4-5 parts of acrylamide, 2-3 parts of cationic monomer 1, 8-10 parts of cationic monomer 2 and 58-62 parts of deionized water; solution B of S2 contains 0.05-0.06 parts of functional monomer, 0.04-0.05 parts of polymerization inhibitor, 0.1-0.2 parts of acrylamide and 2-3 parts of deionized water; in S4, the amount of initiator liquid A and initiator liquid B is 1.5-2.4% of solution A, the amount of solution B is 3-5% of solution A, and the amount of initiator liquid C is 1-2% of solution A.

10. A method for preparing a modified cationic polyacrylamide papermaking strengthening agent, characterized in that: Prepared by the method according to any one of claims 1 to 9.

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