High-viscosity papermaking reinforcing agent and preparation method thereof

Abstract

The invention relates to the technical field of papermaking, in particular to a high-viscosity papermaking reinforcing agent and a preparation method thereof. The method comprises the following steps: 1, mixing acrylamide, N, N '-methylenebis (2-acrylamide), water, an anionic monomer, epoxy chloropropane, disodium ethylene diamine tetraacetate and a chain transfer agent, and initiating a polymerization reaction to obtain an anionic primary composition; step 2, mixing acrylamide, N, N '-methylenebis (2-acrylamide), water, a cationic monomer and a chain transfer agent to obtain a cationic mixed solution, mixing the cationic mixed solution with the anionic primary composition, and initiating a polymerization reaction to obtain an amphoteric copolymerization product; and step 3, preparing acrylamide, a cross-linking agent, water, a cationic monomer, a hydrophobic monomer, maleic anhydride and a chain transfer agent into a modified polymerization solution, and initiating a polymerization reaction to obtain the papermaking reinforcing agent. According to the scheme, the reinforcing agent suitable for high salt concentration can be provided, and the papermaking cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of papermaking, in particular to a high-viscosity papermaking reinforcing agent and a preparation method thereof. BACKGROUND

[0002] Among many papermaking chemicals, paper surface reinforcing agent is very important. The surface strength of paper is directly related to the speed of paper machine, the application performance of paper and the storage life of paper. With the large use of fillers and recycled fibers in the papermaking industry, the strength of paper is reduced, making papermaking reinforcing agent a market demand.

[0003] In recent years, the rapid development of the express industry has brought about a large demand for boxboard paper. Waste paper and other secondary fibers are important raw materials for express packaging boxes and other boxboard papers. The large use of recycled waste paper makes the fibers in the paper pulp shorter and the strength of the paper decreases. With the adjustment of the structure of the papermaking industry, backward papermaking equipment is being eliminated, and new paper machines with high speed and large width are replacing them, which puts higher requirements on the drainage performance of the paper pulp. The closed circulation of white water in papermaking, and the continuous accumulation of inorganic salt electrolytes in white water affect the performance of papermaking chemicals.

[0004] The preparation method of a low-viscosity, low-monomer-residue dry strength agent disclosed in CN114106243A discloses a low-viscosity, low-monomer-residue dry strength agent, but this papermaking reinforcing agent does not contain a crosslinking agent and a hydrophobic monomer, and cannot be used in white water with high salt concentration. The low-viscosity product has a large addition amount and high cost in the papermaking process. SUMMARY

[0005] The present application provides a high-viscosity papermaking reinforcing agent and a preparation method thereof, which can provide a reinforcing agent suitable for high salt concentration and reduce the cost of papermaking.

[0006] In a first aspect, the present application provides a preparation method of a high-viscosity papermaking reinforcing agent, comprising: Step one, mixing acrylamide, N,N'-methylenebis(2-acrylamide), water, anionic monomer, epichlorohydrin, disodium ethylenediaminetetraacetate and chain transfer agent, and initiating polymerization to obtain anionic primary synthetic product; Step two, mixing acrylamide, N,N'-methylenebis(2-acrylamide), water, cationic monomer and chain transfer agent to obtain a cationic mixed solution, mixing the cationic mixed solution with the anionic primary synthetic product, and initiating polymerization to obtain an amphoteric copolymer product; Step three, configuring acrylamide, crosslinking agent, water, cationic monomer, hydrophobic monomer, maleic anhydride and chain transfer agent into a modified polymerization solution, mixing the modified polymerization solution with the amphoteric copolymer product to initiate polymerization, and obtaining a papermaking reinforcing agent.

[0007] In a possible design, the polymerization in step one is carried out in an environment with a pH value of 3.5-4.5, the polymerization in step two is carried out in an environment with a pH value of 2.5-3.0, and the polymerization in step three is carried out in an environment with a pH value of 4.0-4.5.

[0008] In a possible design, the polymerization in step one is carried out in a nitrogen environment at 45-80℃, the polymerization in step two is carried out in a nitrogen environment at 85-95℃, and the polymerization in step three is carried out in a nitrogen environment at 65-80℃.

[0009] In a possible design, the anionic monomer is selected from any one or more of itaconic acid, 2-acrylate-2-methyl methacrylate sulfonic acid sodium; The chain transfer agent is selected from any one or more of sodium formate, isopropyl alcohol, sodium hypophosphite, and sodium methacrylate sulfonate; The crosslinking agent is selected from at least one of N-(hydroxymethyl) acrylamide and diacetone methacrylamide.

[0010] In a possible design, the initiator comprises an azo initiator and a redox initiator; The azo initiator is selected from one or more of azobisdimethylamidino dihydrochloride, azobisdiisopropyl nitrile, azobisdimethyl nitrile, and 4,4'-azobis(4-cyanopentanoic acid); The redox initiator is selected from benzoyl peroxide, ammonium persulfate, potassium persulfate, sodium hydrosulfite formaldehyde, ferrous sulfate, and sodium bisulfite.

[0011] In a possible design, the cationic monomer in step two comprises at least two of (meth) acryloyloxyethyl dimethyl benzyl ammonium chloride, (meth) acryloyloxyethyl trimethyl ammonium chloride, and dimethyl diallyl ammonium chloride.

[0012] In a possible design, the cationic monomer in step three is selected from at least two of (meth) dimethylaminoethyl acrylate, didecyl dimethyl ammonium chloride, didodecyl dimethyl ammonium chloride, and dimethyl diallyl ammonium chloride.

[0013] In a possible design, the hydrophobic monomer is selected from at least one of acrylate, methyl methacrylate, and N-vinyl pyrrolidone.

[0014] In a possible design, the amounts of the components are as follows: Step one: 30wt% acrylamide aqueous solution 150-200 parts by weight, N,N'-methylenebis(2-acrylamide) 1-5 parts by weight, water 50-100 parts by weight, anionic monomer 2-15 parts by weight, epichlorohydrin 2-9 parts by weight, ethylenediaminetetraacetic acid disodium 0.01-1 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight.

[0015] Step two: 30wt% acrylamide aqueous solution 100-150 parts by weight, N,N'-methylenebis(2-acrylamide) 1-5 parts by weight, water 20-70 parts by weight, cationic monomer 15-75 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight.

[0016] Step three: 30wt% acrylamide aqueous solution 50-120 parts by weight, crosslinking agent 1-5 parts by weight, water 50-75 parts by weight, cationic monomer 15-45 parts by weight, hydrophobic monomer 1-7 parts by weight, maleic anhydride 0.5-4 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight.

[0017] In the second aspect, the embodiment of the present application provides a high-viscosity papermaking reinforcing agent prepared according to any of the above preparation methods.

[0018] Compared with the prior art, the present application has at least the following beneficial effects: In the embodiment, anionic primary polymer is synthesized by polymerization reaction of acrylamide, anionic monomer, N,N'-methylenebis(2-acrylamide) and the like. Amphoteric copolymerization product is obtained by polymerization of the anionic primary polymer and cationic monomer. The amphoteric copolymerization product is added with crosslinking agent and cationic monomer to obtain the high-viscosity papermaking reinforcing agent. The hydrophobic monomer of the papermaking reinforcing agent can improve the salt resistance of the product, and the application effect is good in the high-conductivity white water circulating paper machine. The viscosity and charge of the product are improved by amphoteric monomer polymerization and addition of crosslinking agent, and the capture capacity of the papermaking reinforcing agent for fibers in white water is obviously improved by improving the viscosity and optimizing the branched chain structure. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1A preparation method flow chart of a high-viscosity papermaking reinforcing agent is provided in the embodiment of the present application. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] As shown in the figure, the present application provides a preparation method of a high-viscosity papermaking reinforcing agent, comprising: Figure 1 Step one, mixing acrylamide, N,N'-methylenebis(2-acrylamide), water, anionic monomer, epichlorohydrin, disodium ethylenediaminetetraacetate and chain transfer agent, initiating polymerization reaction to obtain anionic primary synthetic product; Step two, mixing acrylamide, N,N'-methylenebis(2-acrylamide), water, cationic monomer and chain transfer agent to obtain a cationic mixed solution, mixing the cationic mixed solution with the anionic primary synthetic product to initiate polymerization reaction, obtaining amphoteric copolymerization product; Step three, configuring acrylamide, crosslinking agent, water, cationic monomer, hydrophobic monomer, maleic anhydride and chain transfer agent into a modified polymerization solution, mixing the modified polymerization solution with the amphoteric copolymerization product to initiate polymerization reaction, obtaining the papermaking reinforcing agent. In the embodiment, anionic primary polymer is synthesized through polymerization reaction of acrylamide, anionic monomer, N,N'-methylenebis(2-acrylamide) and the like. Amphoteric copolymerization product is obtained by polymerization of the anionic primary polymer and cationic monomer. The amphoteric copolymerization product is polymerized with the crosslinking agent and cationic monomer to obtain the high-viscosity papermaking reinforcing agent. The hydrophobic monomer of the papermaking reinforcing agent can improve the salt resistance of the product, and the application effect is good in the high-conductivity white water circulating paper machine. The viscosity and charge of the product are improved by polymerization of amphoteric monomer and addition of crosslinking agent and the like, and the capture ability of the papermaking reinforcing agent for fibers in white water is obviously improved by improving the viscosity and optimizing the branched chain structure.

[0023] In the embodiment, maleic anhydride is added to introduce anhydride groups in the dry strength agent, the anhydride groups and the crosslinking agent are crosslinked to form a network structure, and a covalent bond is formed between the network structure and the fibers, thereby improving the capture ability and binding strength of the fibers in white water.

[0024]

[0025] ​It should be noted that polyacrylamide (PAM) is the core of the synthetic reinforcing agent, but its linear structure has limited "bridging" effect between fibers. When epoxy chloropropane is compounded with cationic PAM, epoxy chloropropane reacts with amide groups or side chain amino groups in PAM molecules as a crosslinking agent to form a three-dimensional network, and the rigidity of the crosslinked PAM molecular chain is enhanced, forming a more stable "mechanical anchor point" between fibers; further, the polar groups introduced by epoxy chloropropane can enhance the hydrogen bonding and electrostatic interaction between PAM and fibers, improving the adsorption efficiency.

[0026] In this embodiment, disodium ethylenediaminetetraacetate is used as a complexing agent, and the molecular structure of disodium ethylenediaminetetraacetate contains four carboxyl groups (-COOH) and two amino groups (-NH-), which can form a stable five-membered ring chelate with metal ions (such as 、 、 、 , etc.) through coordination bonds. N,N'-methylenebisacrylamide is mainly used as a crosslinking agent to enhance viscosity.

[0027] In some embodiments of the present application, the polymerization reaction in step one is carried out in an environment with a pH value of 3.5-4.5 (for example, it can be 3.5, 4 or 4.5), the polymerization reaction in step two is carried out in an environment with a pH value of 2.5-3.0, and the polymerization reaction in step three is carried out in an environment with a pH value of 4.0-4.5.

[0028] In some embodiments of the present application, the polymerization reaction in step one is carried out in a nitrogen environment at 45-80°C (for example, it can be 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C), the polymerization reaction in step two is carried out in a nitrogen environment at 85-95°C (for example, it can be 85°C, 90°C or 95°C), and the polymerization reaction in step three is carried out in a nitrogen environment at 65-80°C (for example, it can be 65°C, 70°C, 75°C or 80°C).

[0029] In some embodiments of the present application, the anionic monomer is selected from any one or more of itaconic acid, 2-acrylic acid-2-methyl methacrylate sodium sulfonate; The chain transfer agent is selected from any one or more of sodium formate, isopropyl alcohol, sodium hypophosphite, and sodium methacrylate sulfonate; The crosslinking agent is selected from at least one of N-(hydroxymethyl) acrylamide and diacetone methacrylamide.

[0030] In some embodiments of the present application, the initiator comprises an azo initiator and a redox initiator. The azo initiator is selected from one or more of azobisdimethylamidino dihydrochloride, azobisisheptyl nitrile, azobisisobutylonitrile, 4,4'-azobis(4-cyanopentanoic acid); The redox initiator is selected from benzoyl peroxide, ammonium persulfate, potassium persulfate, sodium hydrosulfite formaldehyde, ferrous sulfate, sodium bisulfite.

[0031] In some embodiments of the present application, the cationic monomer in step two includes at least two of (meth) acryloyloxyethyl dimethyl benzyl ammonium chloride, (meth) acryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride.

[0032] In embodiments of the present application, it is preferred that one of the cationic monomers is (meth) acryloyloxyethyl trimethyl ammonium chloride. (Meth) acryloyloxyethyl trimethyl ammonium chloride not only increases the cationic degree of the product, but also has a higher reaction activity because its positive charge is far away from the double bond. The positive charge after polymerization and the negative charge on the fiber surface produce adsorption, thereby improving the binding capacity with the fiber.

[0033] In the present embodiment, at least two cationic monomers can significantly increase the salt resistance, fiber capture capacity, and the like of the product.

[0034] In some embodiments of the present application, the cationic monomer in step three is selected from at least two of (meth) dimethylaminoethyl acrylate, dipdecyl dimethyl ammonium chloride, didodecyl dimethyl ammonium chloride, dimethyl diallyl ammonium chloride.

[0035] In embodiments of the present application, the cationic monomer preferably includes (meth) dimethylaminoethyl acrylate. (Meth) dimethylaminoethyl acrylate is a functional cationic monomer. The quaternary lipid type cationic polymer chain synthesized from (meth) dimethylaminoethyl acrylate and acrylamide monomer has stronger hydrophilicity and stronger fiber capture capacity in white water.

[0036] In the present embodiment, at least two cationic monomers can significantly increase the salt resistance, fiber capture capacity, and the like of the product.

[0037] In some embodiments of the present application, the hydrophobic monomer is selected from at least one of acrylate, methyl methacrylate, N-vinyl pyrrolidone.

[0038] In the embodiments, a certain amount of hydrophobic monomers is added to improve the salt resistance and shear resistance of the polymer by adding hydrophobic groups to the polymer molecular chain. The polymer after adding the hydrophobic groups has an amphiphilic structure, which is quite different from general water-soluble polymers. In an aqueous solution, the hydrophobic groups of the polymer associate with each other, and the electrostatic repulsion and attraction of the charged ionic groups compete and cooperate with each other, so that the molecular chains of the polymer produce intramolecular or intermolecular association. In a high electrolyte solution, the hydrophobic association between the hydrophobic groups is significantly enhanced due to the increase in the polarity of the solution, so that the polymer has better salt resistance.

[0039] In some embodiments of the present application, the amount of each component is: Step one: 30wt% acrylamide aqueous solution 150-200 parts by weight, N,N'-methylenebis(2-acrylamide) 1-5 parts by weight, water 50-100 parts by weight, anionic monomer 2-15 parts by weight, epichlorohydrin 2-9 parts by weight, disodium ethylenediaminetetraacetate 0.01-1 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight.

[0040] Step two: 30wt% acrylamide aqueous solution 100-150 parts by weight, N,N'-methylenebis(2-acrylamide) 1-5 parts by weight, water 20-70 parts by weight, cationic monomer 15-75 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight.

[0041] Step three: 30wt% acrylamide aqueous solution 50-120 parts by weight, crosslinking agent 1-5 parts by weight, water 50-75 parts by weight, cationic monomer 15-45 parts by weight, hydrophobic monomer 1-7 parts by weight, maleic anhydride 0.5-4 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight.

[0042] The embodiments of the present application provide a high-viscosity papermaking reinforcing agent prepared according to any of the above preparation methods.

[0043] In order to more clearly illustrate the technical solutions and advantages of the present application, the following will be described in detail through several embodiments.

[0044] Embodiment 1 Step one, anionic polymer primary synthesis: acrylamide monomer aqueous solution, N,N'-methylenebis(2-acrylamide), water, itaconic acid, epichlorohydrin, disodium ethylenediaminetetraacetate, sodium methallyl sulfonate are configured into a mixed solution. A 20% mass fraction sulfuric acid solution is used to adjust the pH value of the mixed solution to 3.7, obtaining a reaction solution. The reaction solution is transferred to a water bath heating four-necked flask, stirring is started, nitrogen is introduced for 25 minutes, and azobisdimethylvaleronitrile dihydrochloride, ammonium persulfate and sodium bisulfite are added at 55 degrees under water bath heating, initiating the polymerization reaction. After 2 hours of reaction, an anionic primary synthesis product is obtained.

[0045] Step two, cationic polymer dropwise synthesis: acrylamide monomer aqueous solution, N,N'-methylenebis(2-acrylamide), water, methacryloyloxyethyl dimethyl benzyl ammonium chloride, dimethyldiallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, sodium methallyl sulfonate are configured into a mixed solution. A 20% mass fraction sulfuric acid solution is used to adjust the pH value of the mixed solution to 2.7, obtaining a cationic polymer dropwise solution. The cationic polymer dropwise solution is transferred to a constant pressure funnel, and is added dropwise to the anionic primary synthesis product under the conditions of nitrogen atmosphere and 88°C water bath constant temperature. After the dropwise addition is completed, azobisdimethylvaleronitrile dihydrochloride, ammonium persulfate and sodium bisulfite are added, and after 1.5 hours of constant temperature, an amphoteric copolymer product is obtained.

[0046] Step three, modified polymer dropwise synthesis: acrylamide monomer aqueous solution, N-(hydroxymethyl) acrylamide, water, dimethylaminoethyl methacrylate, dimethyldiallyl ammonium chloride and didodecyldimethyl ammonium chloride, methyl methacrylate, maleic anhydride, sodium methallyl sulfonate are configured into a modified polymer dropwise solution. A 20% mass fraction sulfuric acid solution is used to adjust the pH value of the mixed solution to 4.3, obtaining a modified polymer dropwise solution. The modified polymer dropwise solution is transferred to a constant pressure funnel, and is added dropwise to the amphoteric copolymer product under the conditions of nitrogen atmosphere and 75°C water bath constant temperature. After the dropwise addition is completed, azobisdimethylvaleronitrile dihydrochloride, ammonium persulfate and sodium bisulfite are added, and after 2 hours of constant temperature, a high-stick paper strength enhancer is obtained.

[0047] The preparation components include: in step one, 30wt% acrylamide aqueous solution 175 parts by weight, N,N'-methylenebis(2-acrylamide) 2 parts by weight, water 75 parts by weight, itaconic acid 5 parts by weight, epichlorohydrin 5 parts by weight, disodium ethylenediaminetetraacetate 0.1 parts by weight, sodium methallyl sulfonate 1.5 parts by weight, azobisdimethylvaleronitrile dihydrochloride 0.3 parts by weight, ammonium persulfate 0.04 parts by weight and sodium bisulfite 0.02 parts by weight.

[0048] In Step two: 125 parts by weight of an aqueous acrylamide monomer solution, 2 parts by weight of N,N'-methylenebis(2-acrylamide), 55 parts by weight of water, 9 parts by weight of methacryloyloxyethyl dimethyl benzyl ammonium chloride, 25 parts by weight of dimethyldiallyl ammonium chloride, 11 parts by weight of methacryloyloxyethyl trimethyl ammonium chloride, 0.3 parts by weight of sodium methallyl sulfonate, 0.1 parts by weight of azobisdimethylvaleronitrile dihydrochloride, 0.02 parts by weight of ammonium persulfate, and 0.01 parts by weight of sodium bisulfite.

[0049] In Step three: 75 parts by weight of an aqueous acrylamide monomer solution, 5 parts by weight of N-(hydroxymethyl) acrylamide, 55 parts by weight of water, 12 parts by weight of dimethylaminoethyl methacrylate, 8 parts by weight of dimethyldiallyl ammonium chloride, and 12 parts by weight of didodecyldimethyl ammonium chloride, 2.5 parts by weight of methyl methacrylate, 0.9 parts by weight of maleic anhydride, 0.3 parts by weight of sodium methallyl sulfonate, 0.1 parts by weight of azobisdimethylvaleronitrile dihydrochloride, 0.02 parts by weight of ammonium persulfate, and 0.01 parts by weight of sodium bisulfite.

[0050] Example 2 In Step one, anionic polymer primary synthesis: an aqueous acrylamide monomer solution, N,N'-methylenebis(2-acrylamide), water, itaconic acid, epichlorohydrin, ethylenediaminetetraacetic acid disodium salt, and sodium methallyl sulfonate were configured into a mixed solution. A 20% mass fraction sulfuric acid solution was used to adjust the pH value of the mixed solution to 3.7, obtaining a reaction solution. The reaction solution was transferred to a water bath heating four-necked flask, stirring was started, nitrogen was introduced for 25 minutes, and the water bath was heated to 55 degrees. Azobisdimethylvaleronitrile dihydrochloride, ammonium persulfate, and sodium bisulfite were added to initiate the polymerization reaction. After 2 hours of reaction, an anionic primary synthesis product was obtained.

[0051] In Step two, cationic polymer dropwise synthesis: an aqueous acrylamide monomer solution, N,N'-methylenebis(2-acrylamide), water, methacryloyloxyethyl dimethyl benzyl ammonium chloride, dimethyldiallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, and sodium methallyl sulfonate were configured into a mixed solution. A 20% mass fraction sulfuric acid solution was used to adjust the pH value of the mixed solution to 2.7, obtaining a cationic polymer dropwise solution. The cationic polymer dropwise solution was transferred to a constant pressure funnel, and was added dropwise to the anionic primary synthesis product under the conditions of a nitrogen atmosphere and a 88°C water bath constant temperature. After the dropwise addition was completed, azobisdimethylvaleronitrile dihydrochloride, ammonium persulfate, and sodium bisulfite were added, and after 1.5 hours of incubation, an amphoteric copolymer product was obtained.

[0052] Step three, modified polymer dropwise synthesis: acrylamide monomer aqueous solution, N-(hydroxymethyl) acrylamide, water, dimethylaminoethyl methacrylate, dimethyldiallylammonium chloride and didodecyldimethylammonium chloride, methyl methacrylate, maleic anhydride, sodium methallyl sulfonate are configured into a modified polymer dropwise solution. A 20% mass fraction of sulfuric acid solution is used to adjust the pH value of the mixed solution to 4.3 to obtain the modified polymer dropwise solution. The modified polymer dropwise solution is transferred to a constant pressure funnel and dropped into the amphoteric copolymer product under the condition of nitrogen atmosphere and 75℃ water bath constant temperature. After the dropwise addition is completed, azobisdimethylaminoformamide dihydrochloride, ammonium persulfate and sodium bisulfite are added, and the high-stick paper strength agent is obtained after 2 hours of incubation.

[0053] The preparation components include: in step one: acrylamide monomer aqueous solution 200 parts by weight, N,N'-methylenebis(2-acrylamide) 1 part by weight, water 50 parts by weight, itaconic acid 5 parts by weight, epichlorohydrin 5 parts by weight, ethylenediaminetetraacetic acid disodium 0.1 parts by weight, sodium methallyl sulfonate 1.5 parts by weight, azobisdimethylaminoformamide dihydrochloride 0.3 parts by weight, ammonium persulfate 0.04 parts by weight and sodium bisulfite 0.02 parts by weight.

[0054] In step two: acrylamide monomer aqueous solution 140 parts by weight, N,N'-methylenebis(2-acrylamide) 2 parts by weight, water 40 parts by weight, methacryloyloxyethyl dimethyl benzyl ammonium chloride 14 parts by weight, dimethyldiallylammonium chloride 30 parts by weight, methacryloyloxyethyl trimethyl ammonium chloride 15 parts by weight, sodium methallyl sulfonate 0.3 parts by weight, azobisdimethylaminoformamide dihydrochloride 0.1 parts by weight, ammonium persulfate 0.02 parts by weight and sodium bisulfite 0.01 parts by weight.

[0055] In step three: acrylamide monomer aqueous solution 80 parts by weight, N-(hydroxymethyl) acrylamide 5 parts by weight, water 55 parts by weight, dimethylaminoethyl methacrylate 16 parts by weight, dimethyldiallylammonium chloride 5 parts by weight and didodecyldimethylammonium chloride 20 parts by weight, methyl methacrylate 2 parts by weight, maleic anhydride 1.3 parts by weight, sodium methallyl sulfonate 0.3 parts by weight, azobisdimethylaminoformamide dihydrochloride 0.1 parts by weight, ammonium persulfate 0.02 parts by weight and sodium bisulfite 0.01 parts by weight.

[0056] Comparative Example 1 Comparative Example 1 is basically the same as Example 2, except that in step two, the cationic monomer is only 59 parts by weight of methacryloyloxyethyl trimethyl ammonium chloride.

[0057] Comparative Example 2 Comparative Example 2 is basically the same as Example 2, except that in step three, the cationic monomer is only 41 parts by weight of dimethylaminoethyl methacrylate.

[0058] Comparative Example 3 Comparative Example 3 is basically the same as Example 2, except that the cationic monomer in Step two only includes 14 parts by weight of methacryloyloxyethyl dimethyl benzyl ammonium chloride 14 and 30 parts by weight of dimethyl diallyl ammonium chloride, without methacryloyloxyethyl trimethyl ammonium chloride (i.e. without the best effective monomer).

[0059] Comparative Example 4 Comparative Example 4 is basically the same as Example 2, except that the cationic monomer in Step three only includes 13 parts by weight of dimethyl diallyl ammonium chloride and 28 parts by weight of didodecyl dimethyl ammonium chloride, without dimethylaminoethyl methacrylate (i.e. without the best effective monomer).

[0060] Comparative Example 5 Comparative Example 5 is basically the same as Example 2, except that maleic anhydride is not added in Step three.

[0061] Comparative Example 6 Comparative Example 6 is basically the same as Example 2, except that the hydrophobic monomer methyl methacrylate is not added.

[0062] Results Statistics (a) Measurement of apparent viscosity The same mass of samples obtained in Examples 1 to 2, Comparative Example 1 and Comparative Example 2, 50 g, was dissolved in 500 ml of deionized water to obtain a 2% test solution, and the dilute viscosity was measured at 62# rotor, 30 r / min, room temperature (25°C) using a Brookfield viscometer (as shown in Table 1).

[0063] (b) Measurement of paperboard bursting strength Paper pulp mixed with broadleaf wood pulp and recycled pulp was used, and various auxiliary materials and paper strengthening agents (Examples 1 and 2, Comparative Examples 1 and 2) were added to the paper pulp according to the specified conditions and sequence, and after being fully stirred and mixed, 10 sheets of each of the paper sheets of Examples 1 and 2, Comparative Examples 1 and 2 were obtained using a FaiBo wet fiber generator, and after drying, the test paper sheets of Examples 1 and 2, Comparative Examples 1 and 2 were obtained.

[0064] According to the method for measuring the bursting strength of paperboard in GB / T 13024-2016, 10 sheets of each of the test paper sheets of Examples 1 and 2, Comparative Examples 1 and 2 were cut into 10 cm x 10 cm using a cutting instrument, and the bursting strength was measured using a BSM-6000 type paperboard bursting strength tester, and the average value was taken to obtain the bursting strength (as shown in Table 2).

[0065] (c) Measurement of paperboard folding endurance The paper pulp mixed with broadleaf wood pulp and recycled fiber recovery pulp was added with various auxiliary materials and paper reinforcing agents according to the specified conditions and sequence (Examples 1 and 2, and Comparative Examples 1 and 2) in the paper pulp, and after being fully stirred and uniformly mixed, 10 paper sheets were prepared by using a FABO wet fiber generator, and after drying, the paper sheets for testing of Examples 1 and 2, and Comparative Examples 1 and 2 were obtained.

[0066] According to the method for determining the folding endurance of paperboard in GB / T 13024-2016, 10 paper sheets of the boxboard paper of Examples 1 and 2, and Comparative Examples 1 and 2 were taken, a cutting instrument was used to cut the sample width to 15.0 mm ± 0.1 mm, a FABO MIT folding endurance tester was used to apply a tension of 9.8 ± 0.2 N, a double-fold test was adopted, the number of double folds at the time of sample fracture was tested and the average value was taken, and the number of folds was obtained (as shown in Table 3).

[0067] Table 1 Table 2 Table 3

[0068] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of a high viscosity paper strengthening agent, characterized in that, Comprising: Step one, acrylamide, N, N'-methylene bis (2-acrylamide), water, anionic monomer, epoxy chloropropane, ethylenediaminetetraacetic acid disodium and chain transfer agent mixed, after the initiation of polymerization to get anionic primary synthesis; Step two, acrylamide, N, N'-methylene bis (2-acrylamide), water, cationic monomer and chain transfer agent mixed to get cationic mixed solution, after mixing the cationic mixed solution with the anionic primary synthesis, the polymerization reaction is initiated to get amphoteric copolymerization product; Step three, acrylamide, crosslinking agent, water, cationic monomer, hydrophobic monomer, maleic anhydride, chain transfer agent are configured into modified polymerization solution, the modified polymerization solution and the amphoteric copolymerization product are mixed to initiate polymerization reaction, and paper strengthening agent is obtained.

2. The production method according to claim 1, characterized by, The polymerization reaction in step one is carried out in an environment with a pH value of 3.5-4.5, the polymerization reaction in step two is carried out in an environment with a pH value of 2.5-3.0, and the polymerization reaction in step three is carried out in an environment with a pH value of 4.0-4.

5.

3. The production method according to claim 1, characterized by, The polymerization reaction in step one is carried out in a nitrogen environment at 45-80℃, the polymerization reaction in step two is carried out in a nitrogen environment at 85-95℃, and the polymerization reaction in step three is carried out in a nitrogen environment at 65-80℃.

4. The method of claim 1, wherein, The anionic monomer is selected from any one or more of itaconic acid, 2-acrylic acid-2-methyl methacrylate sulfonic acid sodium; The chain transfer agent is selected from any one or more of sodium formate, isopropyl alcohol, sodium hypophosphite, sodium methacrylate sulfonate; The crosslinking agent is at least one of N- (hydroxymethyl) acrylamide, diacetone methacrylamide.

5. The preparation method according to claim 1, characterized in that, The initiator comprises an azo initiator and a redox initiator; The azo initiator is selected from one or more of azobisdimethylamidinum dihydrochloride, azobisdimethylhexyl nitrile, azobisdimethyl nitrile, 4, 4'-azobis (4-cyanopentanoic acid) ; The redox initiator is selected from benzoyl peroxide, ammonium persulfate, potassium persulfate, sodium hydrosulfite formaldehyde, ferrous sulfate, sodium bisulfite.

6. The method of claim 1, wherein, The cationic monomer in step two comprises at least two of (methyl) acryloyloxyethyl dimethyl benzyl ammonium chloride, (methyl) acryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride.

7. The preparation method according to claim 1, characterized in that, The cationic monomer in step three is selected from at least two of (methyl) dimethylaminoethyl acrylate, dipentaerythritol dimethyl ammonium chloride, didodecyl dimethyl ammonium chloride, dimethyl diallyl ammonium chloride.

8. The method of claim 1, wherein, The hydrophobic monomer is selected from at least one of acrylate, methyl methacrylate, N-vinyl pyrrolidone.

9. The method of claim 1, wherein, The amount of each component is: Step one: 30wt% acrylamide aqueous solution 150-200 parts by weight, N, N'-methylene bis (2-acrylamide) 1-5 parts by weight, water 50-100 parts by weight, anionic monomer 2-15 parts by weight, epoxy chloropropane 2-9 parts by weight, ethylenediaminetetraacetic acid disodium 0.01-1 parts by weight, chain transfer agent 0.05-1.8 parts by weight and initiator 0.001-0.5 parts by weight; Step two: 100-150 parts by weight of 30 wt% acrylamide aqueous solution, 1-5 parts by weight of N,N'-methylenebis(2-acrylamide), 20-70 parts by weight of water, 15-75 parts by weight of cationic monomer, 0.05-1.8 parts by weight of chain transfer agent, and 0.001-0.5 parts by weight of initiator; Step three: 50-120 parts by weight of 30 wt% acrylamide aqueous solution, 1-5 parts by weight of crosslinking agent, 50-75 parts by weight of water, 15-45 parts by weight of cationic monomer, 1-7 parts by weight of hydrophobic monomer, 0.5-4 parts by weight of maleic anhydride, 0.05-1.8 parts by weight of chain transfer agent, and 0.001-0.5 parts by weight of initiator.

10. A high viscosity papermaking strengthening agent characterized in that, Prepared according to any one of the preparation methods of claims 1-9. Prepared according to any one of the preparation methods of claims 1-9.

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