Guar gum modification enhancer as well as preparation method and application thereof

Abstract

The invention discloses a guar gum modification enhancer as well as a preparation method and application thereof, the preparation method comprises the following steps: uniformly stirring guar gum raw materials, a catalyst, a polymerization inhibitor and organic unsaturated acid (anhydride), heating to 90-160 DEG C, and reacting for a period of time to prepare esterification modified guar gum; the esterification modified guar gum is dissolved in water, the pH value is adjusted to be 3-5 with acid, nitrogen is introduced, the temperature is increased to 60-85 DEG C, a first initiator and a monomer mixture solution are dropwise added respectively, the temperature is controlled to be 70-95 DEG C in the dropwise adding process, and the first initiator is dropwise added later than the monomer mixture solution; adding a first initiator, dropwise adding a second initiator after heat preservation for a period of time, carrying out heat preservation reaction at 80-90 DEG C, and adding a terminating agent to terminate the reaction when the viscosity of the reaction liquid reaches 3000-15000mPa. S, so as to obtain the guar gum modified reinforcing agent. The reinforcing agent disclosed by the invention can be used for effectively improving retention and drainage assisting effects while ensuring the strength of paper.

Description

Technical Field

[0001] The invention relates to the technical field of paper reinforcing agents, and in particular to a guar gum modified reinforcing agent and a preparation method and application thereof. Background Art

[0002] In recent years, as waste paper is recycled more and more times, the strength of fiber raw materials has become increasingly poor. At the same time, in order to save energy, reduce emissions and cut costs, more and more manufacturers have added sludge, sawdust, etc. during papermaking, resulting in further reduction in paper strength. For this reason, reinforcing agents need to be added during papermaking to compensate for the strength of the paper.

[0003] In the prior art, cationic starch, polyacrylamide dry strength agent and cationic guar gum are commonly used as strengthening agents, but the retention rate of cationic starch is low, which can easily cause abnormally high BOD and COD of white water, and increase the cost of white water treatment; cationic guar gum has a low degree of substitution and has a good retention effect on thin paper, but the strengthening effect is limited; and although the polyacrylamide dry strength agent can effectively enhance the strength of paper, it will affect the water filtration performance. Summary of the invention

[0004] In order to overcome the above disadvantages, the purpose of the present invention is to provide a guar gum modified enhancer and a preparation method and application thereof, which can effectively improve the retention and filtration effects while ensuring the strength of paper.

[0005] In order to achieve the above object, one of the technical solutions adopted by the present invention is: a method for preparing a guar gum modified enhancer, comprising the following steps: (1) Add guar gum raw material, catalyst, inhibitor, and organic unsaturated acid (anhydride) into a reaction kettle and stir evenly, heat to 90-160°C and react for a period of time to obtain esterified modified guar gum; (2) dissolving the esterified modified guar gum in water, adjusting the pH value to between 3 and 5 with acid, passing nitrogen and heating to 60 to 85° C., respectively dropping a first initiator and a monomer mixture solution with a concentration of 30% to 60%, wherein the temperature is controlled between 70 and 95° C. during the dropping process, and the first initiator is dropped later than the monomer mixture solution; after keeping the temperature for a period of time, dropping a second initiator, and keeping the temperature between 80 and 90° C. for reaction, when the viscosity of the reaction liquid reaches 3000 to 15000 mPa·s, adding a terminator to terminate the reaction, thereby obtaining a guar gum modified enhancer; wherein the monomer mixture solution comprises a monomer mixture and water, and the monomer mixture comprises a first monomer, a second monomer, a third monomer, a cross-linking agent and a molecular weight regulator; The first monomer is selected from at least one of acrylamide, methacrylamide, and N,N-dimethylacrylamide; The second monomer is selected from at least one of dimethyldiallylammonium chloride, dimethylaminoethyl acrylate, acryloyloxyethyldimethylbenzylammonium chloride, acryloyloxyethyltrimethylammonium chloride, dimethylaminoethyl methacrylate, methacryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, diethylaminoethyl acrylate, acryloyloxyethyldiethylbenzylammonium chloride, acryloyloxyethylmethyldiethylammonium chloride, diethylaminoethyl methacrylate, methacryloyloxyethyldiethylbenzylammonium chloride, methacryloyloxyethylmethyldiethylammonium chloride, dimethylaminopropylacrylamide, acryloyltrimethylammonium chloride, dimethylaminopropylmethacrylamide, and methacryloylpropyltrimethylammonium chloride; The third monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, sodium vinylbenzene sulfonate, and styrene sulfonic acid.

[0006] The beneficial effects of the preparation method of the guar gum modified reinforcing agent of the present invention are: In step (1), a carbon-carbon double bond is introduced into the guar gum structure through an esterification reaction between guar gum and an organic unsaturated acid (or an organic unsaturated acid anhydride), and the unsaturated carbon-carbon double bond is used to provide a reaction point for the next step of graft polymerization. Since the carbon-carbon double bond is an unsaturated monomer, the ratio of the cation or anion introduced by grafting is relatively convenient to adjust, thereby solving the problem of low graft substitution degree of cationic guar gum in the prior art. In step (2), under the action of the first initiator and the second initiator, the carbon-carbon double bond on the esterified modified guar gum can undergo a free radical polymerization reaction with the first monomer, the second monomer, and the third monomer in the monomer mixture, and the large number of amide groups, The active or cross-linking groups such as amino, quaternary ammonium, carboxyl, sulfonic acid, and hydroxyl groups, and the active or cross-linking groups such as hydroxyl and galacturonic acid provided by guar gum in the free radical polymerization reaction enable the amide and hydroxyl groups to hydrogen bond with the hydroxyl groups in the paper fibers, the amino and quaternary ammonium groups to ionically bond with the carboxyl groups on the paper fibers, and the carboxyl, sulfonic acid, and galacturonic acid to coordinately bond with the carboxyl groups on the paper fibers through aluminum ions. Under the action of the above-mentioned multiple binding forces, the paper fibers can form a dense three-dimensional network structure, and the junctions of the network points are hydrogen bonded, ionic bonded, or coordinated bonded, thereby synergistically exerting the enhancement, retention, and filtration-aiding effects of guar gum and polyacrylamide, thereby improving the dry strength of the paper such as the ring crush strength, interlayer bonding strength, and bursting resistance.

[0007] In addition, in step (2), adding the initiator twice can ensure that the free radical polymerization reaction proceeds more fully and thoroughly, and eliminate the residual unsaturated monomers in the monomer mixture as much as possible.

[0008] Specifically, the mass ratio of the esterified modified guar gum to the monomer mixture is 1-15:85-99; the mass ratio of the first monomer, the second monomer, and the third monomer is 65-90:5-30:3-15.

[0009] Furthermore, the total amount of the first initiator and the second initiator is 0.1% to 2% of the mass of the modified enhancer, wherein the amount of the first initiator accounts for 50% to 80% of the total amount of the first initiator and the second initiator, and the amount of the second initiator accounts for 20% to 50% of the total amount of the first initiator and the second initiator.

[0010] Furthermore, the first initiator and the second initiator are both water-soluble initiators, and the water-soluble initiator is selected from at least one of ammonium persulfate, sodium persulfate, potassium persulfate, ammonium cerium nitrate, azobisisobutyramidine hydrochloride, azobisisopropylimidazoline hydrochloride, sodium bisulfite, and sodium pyrosulfite.

[0011] Furthermore, the guar gum raw material is selected from at least one of natural guar gum, hydroxyethyl guar gum, hydroxypropyl guar gum, carboxymethyl guar gum, carboxymethyl hydroxypropyl guar gum, carboxymethyl hydroxyethyl guar gum, cationic guar gum, cationic hydroxypropyl guar gum, cationic hydroxyethyl guar gum and amphoteric guar gum.

[0012] Further, the catalyst is selected from at least one of sulfuric acid, phosphoric acid, and p-toluenesulfonic acid; the inhibitor is selected from at least one of p-methoxyphenol, hydroquinone, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, and methylhydroquinone; and the organic unsaturated acid (anhydride) is selected from at least one of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, and itaconic acid.

[0013] Further, the acid is selected from at least one of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and citric acid; the cross-linking agent is selected from at least one of N,N-methylenebisacrylamide, N-hydroxymethylacrylamide, polyethylene glycol diallyl ether, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol triallyl ether, pentaerythritol triacrylate, dipentaerythritol hexaallyl ether, dipentaerythritol hexaacrylate, and 1,3,5-triacrylamide-hexahydrotriazine; the molecular weight regulator is selected from at least one of sodium hypophosphite, sodium pyrosulfite, sodium sulfite, sodium bisulfite, sodium formate, isopropyl alcohol, sodium propylene sulfonate, and sodium methyl propylene sulfonate; the terminator is selected from at least one of sodium sulfite, sodium pyrosulfite, sodium bisulfite, sodium thiosulfate, p-hydroxyanisole, and sodium ascorbate.

[0014] Furthermore, the amount of the cross-linking agent used accounts for 0.01% to 0.5% of the mass of the guar gum modified reinforcing agent.

[0015] The second technical solution adopted by the present invention is: a guar gum modified reinforcing agent, which is prepared by any of the above-mentioned preparation methods. The guar gum modified reinforcing agent of the present invention can synergistically exert the reinforcing, retention and filtration effects of guar gum and polyacrylamide, improve the dry strength such as the ring crush strength, interlayer bonding strength and bursting resistance of paper, and is particularly suitable for paper reinforcement scenarios with a large amount of sludge and sawdust added, and has excellent retention and retention effects, and is easily biodegradable and green and environmentally friendly.

[0016] The third technical solution adopted by the present invention is: application of the above guar gum modified enhancer in papermaking. DETAILED DESCRIPTION

[0017] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the protection scope of the present invention. It should be noted that the following embodiments are for a better understanding of the present invention, are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0018] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0019] In addition, if the specific experimental steps or conditions are not specified in the examples, the operations or conditions of the conventional experimental steps described in the literature in the art can be carried out. The numerical ranges shown by "~" in the examples indicate the ranges containing the values ​​recorded before and after "~" as the minimum and maximum values, respectively. If the manufacturers of the reagents or instruments are not specified, they are all conventional reagent products that can be obtained commercially.

[0020] A method for preparing a guar gum modified enhancer of the present invention comprises the following steps: (1) Preparation of esterified modified guar gum containing a carbon-carbon double bond structure: adding guar gum raw material, catalyst, inhibitor, and organic unsaturated acid (anhydride) into a reaction kettle and stirring evenly, heating to 90-160° C. and reacting for 15-180 min to obtain esterified modified guar gum; (2) Preparation of guar gum modified enhancer: dissolve esterified modified guar gum in water, adjust pH value to 3-5 with acid, pass nitrogen and heat to 60-85°C, add a first initiator and a monomer mixture solution with concentration of 30%-60% dropwise respectively, control the temperature to 70-95°C during the addition, and drip the monomer mixture solution within 30-120 min, drip the first initiator within 45-135 min, and drip the first initiator 15 min later than the monomer mixture solution; after dripping the first initiator, keep the temperature at 82-92°C for 15 min, add a second initiator dropwise, and keep the temperature at 80-90°C for reaction, when the viscosity of the reaction liquid reaches 3000-15000 mPa·s, add a terminator to terminate the reaction, and obtain the guar gum modified enhancer.

[0021] Specifically, the monomer mixture solution includes a monomer mixture and water, and the monomer mixture includes a first monomer, a second monomer, a third monomer, a cross-linking agent and a molecular weight regulator.

[0022] The first monomer is selected from at least one of acrylamide, methacrylamide and N,N-dimethylacrylamide.

[0023] The second monomer is selected from at least one of dimethyldiallylammonium chloride, dimethylaminoethyl acrylate, acryloyloxyethyldimethylbenzylammonium chloride, acryloyloxyethyltrimethylammonium chloride, dimethylaminoethyl methacrylate, methacryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, diethylaminoethyl acrylate, acryloyloxyethyldiethylbenzylammonium chloride, acryloyloxyethylmethyldiethylammonium chloride, diethylaminoethyl methacrylate, methacryloyloxyethyldiethylbenzylammonium chloride, methacryloyloxyethylmethyldiethylammonium chloride, dimethylaminopropylacrylamide, acryloyltrimethylammonium chloride, dimethylaminopropylmethacrylamide, and methacryloylpropyltrimethylammonium chloride.

[0024] The third monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, sodium vinylbenzene sulfonate, and styrene sulfonic acid.

[0025] The crosslinking agent is selected from at least one of N,N-methylenebisacrylamide, N-hydroxymethylacrylamide, polyethylene glycol diallyl ether, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol triallyl ether, pentaerythritol triacrylate, dipentaerythritol hexaallyl ether, dipentaerythritol hexaacrylate, and 1,3,5-triacrylamide-hexahydrotriazine.

[0026] The molecular weight regulator is selected from at least one of sodium hypophosphite, sodium pyrosulfite, sodium sulfite, sodium bisulfite, sodium formate, isopropyl alcohol, sodium propylene sulfonate and sodium methpropylene sulfonate.

[0027] It should be noted that the organic unsaturated acid (anhydride) refers to an organic unsaturated acid or an organic unsaturated acid anhydride.

[0028] In the prior art, when guar gum is used as a reinforcing agent, it is usually modified by etherification to introduce carboxyl, hydroxypropyl, hydroxyethyl, cationic groups, etc. into the guar gum. These modified grafts are all saturated groups, and the number of anions / cations that can be introduced is limited. In addition, the product structure is relatively simple, resulting in poor reinforcing effect on paper. However, the present invention introduces unsaturated carbon-carbon double bonds into guar gum through esterification reaction to provide reaction points for carbon-carbon double bonds for free radical polymerization in the next step. The product structure, acrylamide, and anion / cation ratio are relatively convenient to adjust, which is conducive to the synergistic retention, drainage and reinforcing effects of guar gum and polyacrylamide reinforcing agent.

[0029] Furthermore, the mass ratio of the esterified modified guar gum to the monomer mixture is 1-15:85-99. The mass ratio of the first monomer, the second monomer, and the third monomer is 65-90:5-30:3-15. The amount of the crosslinking agent accounts for 0.01%-0.5% of the mass of the guar gum modified reinforcing agent.

[0030] In some embodiments, the total amount of the first initiator and the second initiator is 0.1% to 2% of the mass of the modified enhancer, wherein the amount of the first initiator accounts for 50% to 80% of the total amount of the first initiator and the second initiator, and the amount of the second initiator accounts for 20% to 50% of the total amount of the first initiator and the second initiator.

[0031] The first initiator and the second initiator are both water-soluble initiators, and the water-soluble initiator is selected from at least one of ammonium persulfate, sodium persulfate, potassium persulfate, cerium ammonium nitrate, azobisisobutylamidine hydrochloride, azobisisopropylimidazoline hydrochloride, sodium bisulfite, and sodium pyrosulfite. Adding the first initiator and the second initiator twice can make the polymerization reaction more thorough and eliminate the residual unsaturated monomers in the reaction solution as much as possible.

[0032] In step (1), the guar gum raw material is selected from at least one of natural guar gum, hydroxyethyl guar gum, hydroxypropyl guar gum, carboxymethyl guar gum, carboxymethyl hydroxypropyl guar gum, carboxymethyl hydroxyethyl guar gum, cationic guar gum, cationic hydroxypropyl guar gum, cationic hydroxyethyl guar gum and amphoteric guar gum.

[0033] The catalyst is selected from at least one of sulfuric acid, phosphoric acid and p-toluenesulfonic acid.

[0034] The polymerization inhibitor is at least one selected from p-methoxyphenol, hydroquinone, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone and methylhydroquinone.

[0035] The organic unsaturated acid (anhydride) is at least one selected from acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, and itaconic acid.

[0036] In step (2), the acid is selected from at least one of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and citric acid.

[0037] The terminator is selected from at least one of sodium sulfite, sodium pyrosulfite, sodium bisulfite, sodium thiosulfate, p-hydroxyanisole, and sodium ascorbate.

[0038] Example 1 The guar gum modified enhancer was prepared as follows: Add 100 parts of natural guar gum to the reactor, start stirring, add 1 part of 50% sulfuric acid, 0.15 parts of p-methoxyphenol, and 5 parts of acrylic acid, stir evenly, heat to 100°C, react at 110°C for 60 minutes, and stir continuously during the reaction to obtain esterified modified guar gum; 600 parts of deionized water were added into a reactor, stirring was started, and 10 parts of esterified modified guar gum were slowly added. After the mixture was completely dissolved, the pH value was adjusted to 3.2 with 20% sulfuric acid under stirring, nitrogen was passed, the temperature was raised to 73°C, 22 parts of 5% ammonium persulfate aqueous solution and 284 parts of monomer mixture solution were added dropwise, the monomer mixture solution was added dropwise within 60 minutes, and the ammonium persulfate aqueous solution was added dropwise within 75 minutes. During the addition process, the temperature was controlled between 73°C and 92°C. After the addition was completed, the mixture was kept warm at 82°C to 95°C for 15 minutes. 10 parts of 5% ammonium persulfate aqueous solution were added, and the mixture was kept warm at 80°C to 90°C for reaction. When the viscosity of the reaction solution reached 6000 mPa·s, sodium sulfite was added to terminate the reaction, and a guar gum modified enhancer with a solid content of 15.4% was obtained. The monomer mixture solution includes 220 parts of a 50% acrylamide aqueous solution, 5 parts of dimethylaminoethyl acrylate, 11 parts of methacryloyloxyethyl dimethylbenzyl ammonium chloride, 10 parts of acryloyloxyethyl trimethyl ammonium chloride, 7 parts of itaconic acid, 1.8 parts of acrylic acid, 0.05 parts of N,N-methylenebisacrylamide, 4 parts of sodium methacrylic acid, 0.2 parts of sodium hypophosphite, and the balance is deionized water.

[0039] Example 2 The guar gum modified enhancer was prepared as follows: Add 100 parts of cationic guar gum (Rhodia C-16, France) to the reactor, start stirring, add 0.8 parts of p-toluenesulfonic acid, 0.2 parts of 2,6-di-tert-butyl-p-cresol, and 8 parts of maleic anhydride, stir evenly, and heat to 120°C. React at 120°C for 30 minutes. Stir continuously during the reaction to obtain esterified modified guar gum; 600 parts of deionized water were added into a reactor, stirring was started, 9 parts of esterified modified guar gum were slowly added, and after complete dissolution, 50% hydrochloric acid was used to adjust the pH value to 3.3 under stirring, nitrogen was passed, the temperature was raised to 76°C, 25 parts of 5% potassium persulfate aqueous solution and 289.8 parts of monomer mixture solution were added dropwise, the monomer mixture solution was added dropwise within 80 minutes, and the ammonium persulfate aqueous solution was added dropwise within 95 minutes. During the dropping process, the temperature was controlled between 76 and 92°C, and after the dropping was completed, the temperature was kept at 86 to 92°C for 15 minutes, 10 parts of 5% potassium persulfate aqueous solution were added, and the temperature was kept at 83 to 88°C for reaction, and when the viscosity of the reaction liquid reached 7500 mPa·s, sodium bisulfite was added to terminate the reaction, and a guar gum modified enhancer with a solid content of 15.1% was obtained. The monomer mixture solution includes 220 parts of 50% acrylamide aqueous solution, 5 parts of dimethylaminoethyl methacrylate, 5 parts of dimethylaminoethyl acrylate, 5 parts of dimethyldiallylammonium chloride, 10 parts of methacryloyloxyethyltrimethylammonium chloride, 4.5 parts of itaconic acid, 4.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, 0.02 parts of pentaerythritol triallyl ether, 0.01 parts of N,N-methylenebisacrylamide, 5.8 parts of sodium propylene sulfonate, and the balance is deionized water.

[0040] Example 3 The guar gum modified enhancer was prepared as follows: Add 100 parts of carboxymethyl guar gum to the reactor, start stirring, add 0.75 parts of p-toluenesulfonic acid, 0.5 parts of 50% sulfuric acid, 0.05 parts of hydroquinone, 0.1 parts of 2,4-dimethyl-6-tert-butylphenol, 5 parts of itaconic acid, and 5 parts of methacrylic acid, stir evenly, heat to 140°C, react at 150°C for 20 minutes, and stir continuously during the reaction to obtain esterified modified guar gum; 600 parts of deionized water were added into a reactor, stirring was started, 12 parts of esterified modified guar gum were slowly added, and after complete dissolution, the pH value was adjusted to 3.5 with acetic acid under stirring, nitrogen was passed, the temperature was raised to 80°C, 30 parts of 5% sodium persulfate aqueous solution and 357.5 parts of monomer mixture solution were dripped, the monomer mixture solution was dripped within 105 minutes, and the sodium persulfate aqueous solution was dripped within 120 minutes. During the dripping process, the temperature was controlled between 80 and 95°C. After the dripping was completed, the temperature was kept at 86 to 93°C for 15 minutes, 10 parts of 5% azobisisobutylamidine hydrochloride aqueous solution were added, and the temperature was kept at 85 to 90°C for reaction. When the viscosity of the reaction liquid reached 8500 mPa·s, sodium pyrosulfite was added to terminate the reaction, and a guar gum modified enhancer with a solid content of 15.6% was obtained. The monomer mixture solution includes 230 parts of 50% acrylamide aqueous solution, 1 part of N,N-dimethylacrylamide, 15 parts of dimethyldiallyl ammonium chloride, 10 parts of methacryloyloxyethyltrimethylammonium chloride, 10 parts of dimethylaminopropyl methacrylamide, 2 parts of itaconic acid, 4.5 parts of acrylic acid, 0.02 parts of N,N-methylenebisacrylamide, 0.01 parts of polyethylene glycol diallyl ether, 5 parts of sodium methacrylic acid, and the balance is deionized water.

[0041] Comparative Example 1 The cationic guar gum grafted polyacrylamide reinforcing agent was prepared as follows: 600 parts of deionized water were added into the reactor, stirring was started, and 10 parts of cationic guar gum were slowly added. After the solution was completely dissolved, the pH value was adjusted to 3.2 with 20% sulfuric acid, nitrogen was passed, the temperature was raised to 73°C, 22 parts of 5% ammonium persulfate aqueous solution and 284 parts of monomer mixture solution were added dropwise, the monomer mixture solution was dripped within 75 minutes, and the 5% ammonium persulfate aqueous solution was dripped within 90 minutes. The temperature was controlled between 73°C and 92°C during the dripping process; after the dripping was completed, the temperature was kept between 82°C and 95°C for 15 minutes, 10 parts of 5% ammonium persulfate aqueous solution were added, and the reaction was continued at 80°C and 90°C. When the viscosity reached 6000mPa.s, sodium sulfite was added to terminate the reaction, and a cationic guar gum grafted polyacrylamide enhancer with a solid content of 15.3% was obtained. Among them, the monomer mixture solution includes 220 parts of 50% acrylamide aqueous solution, 5 parts of dimethylaminoethyl acrylate, 11 parts of methacryloyloxyethyl dimethylbenzyl ammonium chloride, 10 parts of acryloyloxyethyl trimethyl ammonium chloride, 7 parts of itaconic acid, 1.8 parts of acrylic acid, 0.05 parts of N,N-methylenebisacrylamide, 4 parts of sodium methacrylic acid, and 0.2 parts of sodium hypophosphite.

[0042] Comparative Example 2 The compound reinforcing agent of cationic guar gum and acrylamide dry strength agent was prepared according to the following steps: 170 parts of deionized water were added into the reactor, stirring was started, 5 parts of cationic guar gum were slowly added into the reactor, after stirring and dissolving completely, 725 parts of HM-2900 dry strength agent were added, and stirring was continued to be uniform, thus obtaining a 15% compound reinforcing agent.

[0043] Comparative Example 3 The amphoteric polyacrylamide dry strength agent sold by Hangzhou Harima Company was used as the reinforcing agent, wherein the solid content was 20%, and the product model was HM-2900.

[0044] Application Examples The modified reinforcing agents prepared in Examples 1-3 and the reinforcing agents in Comparative Examples 1-3 were evaluated for application, and the addition amount was 3.0 kg / t paper on an absolute dry basis. The test items included paper strength performance, water filtration, and ash retention.

[0045] The pulp used for sheet making is waste paper pulp, wood fiber, and papermaking sludge, with a mass percentage of 87:10:3 and a beating degree of 31°SR. The pulp concentration is diluted to 1.0% with tap water, and the filler is added in an amount of 15%. The sheet is made into 0.03m thick sheets using a KRK2542-A semi-automatic sheet former (KRK, Japan). 2 Round paper sheet, paper weight is 100g / m 2 After being dried in a rotary dryer and balanced under standard temperature and humidity conditions for 24 hours, the paper was tested for its ring crush index, internal bonding strength and bursting strength, water filtration (Canadian freeness meter) and ash content. The test results are shown in Table 1.

[0046] Table 1 Test results of paper properties of Examples 1-3 and Comparative Examples 1-3

[0047] According to Table 1, we can see that: 1. Under the same dosage, the ring crush index, internal bonding strength and bursting index of the modified reinforcing agent prepared by using Examples 1-3 of the present invention are better than those of Comparative Examples 1-3, which shows that the modified reinforcing agent of the present invention has a better reinforcing effect on the strength of paper; the water filtration amount of the modified reinforcing agent prepared by using Examples 1-3 of the present invention is significantly greater than that of Comparative Examples 1-3, and the grayscale is also significantly higher than that of Comparative Examples 1-3, which shows that the modified reinforcing agent of the present invention has better retention and filtration effects.

[0048] 2. According to the test results of Example 1 and Comparative Example 1, it can be known that in Comparative Example 1, cationic guar gum is directly grafted and copolymerized onto polyacrylamide. Although the copolymerization reaction can synergistically exert the enhancement, retention and drainage effects of guar gum and polyacrylamide, the cationic guar gum lacks unsaturated groups such as carbon-carbon double bonds, resulting in a low grafting rate of the cationic guar gum and a low degree of polymerization between the cationic guar gum and the polyacrylamide, thereby affecting the final enhancement effect.

[0049] 3. According to the test results of Example 1 and Comparative Example 2, the cationic guar gum and the polyacrylamide dry strength agent are directly compounded for use in Comparative Example 2. Since the guar gum and the polyacrylamide do not undergo a polymerization reaction, the reinforcing agent of Comparative Example 2 can only play the reinforcing role of the cationic guar gum and the polyacrylamide dry strength agent separately, and cannot achieve a synergistic reinforcing effect.

[0050] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a guar gum modified enhancer, characterized in that: The steps include: (1) Add guar gum raw material, catalyst, inhibitor, and organic unsaturated acid (anhydride) into a reaction kettle and stir evenly, heat to 90-160°C and react for a period of time to obtain esterified modified guar gum; (2) dissolving the esterified modified guar gum in water, adjusting the pH value to between 3 and 5 with acid, passing nitrogen and heating to 60 to 85° C., respectively dropping a first initiator and a monomer mixture solution with a concentration of 30% to 60%, wherein the temperature is controlled between 70 and 95° C. during the dropping process, and the first initiator is dropped later than the monomer mixture solution; after keeping the temperature for a period of time, dropping a second initiator, and keeping the temperature between 80 and 90° C. for reaction, when the viscosity of the reaction liquid reaches 3000 to 15000 mPa·s, adding a terminator to terminate the reaction, thereby obtaining a guar gum modified enhancer; wherein the monomer mixture solution comprises a monomer mixture and water, and the monomer mixture comprises a first monomer, a second monomer, a third monomer, a cross-linking agent and a molecular weight regulator; The first monomer is selected from at least one of acrylamide, methacrylamide, and N,N-dimethylacrylamide; The second monomer is selected from at least one of dimethyldiallylammonium chloride, dimethylaminoethyl acrylate, acryloyloxyethyldimethylbenzylammonium chloride, acryloyloxyethyltrimethylammonium chloride, dimethylaminoethyl methacrylate, methacryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, diethylaminoethyl acrylate, acryloyloxyethyldiethylbenzylammonium chloride, acryloyloxyethylmethyldiethylammonium chloride, diethylaminoethyl methacrylate, methacryloyloxyethyldiethylbenzylammonium chloride, methacryloyloxyethylmethyldiethylammonium chloride, dimethylaminopropylacrylamide, acryloyltrimethylammonium chloride, dimethylaminopropylmethacrylamide, and methacryloylpropyltrimethylammonium chloride; The third monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, sodium vinylbenzene sulfonate, and styrene sulfonic acid.

2. The preparation method of the guar gum modifier according to claim 1, characterized in that: The mass ratio of the esterified modified guar gum to the monomer mixture is 1-15:85-99; the mass ratio of the first monomer, the second monomer, and the third monomer is 65-90:5-30:3-15.

3. The preparation method of the guar gum modifying and reinforcing agent according to claim 2, characterized in that: The total amount of the first initiator and the second initiator is 0.1% to 2% of the mass of the modified enhancer, wherein the amount of the first initiator accounts for 50% to 80% of the total amount of the first initiator and the second initiator, and the amount of the second initiator accounts for 20% to 50% of the total amount of the first initiator and the second initiator.

4. The preparation method of the guar gum modifying and reinforcing agent according to claim 3, characterized in that: The first initiator and the second initiator are both water-soluble initiators, and the water-soluble initiator is selected from at least one of ammonium persulfate, sodium persulfate, potassium persulfate, ammonium cerium nitrate, azobisisobutyramidine hydrochloride, azobisisopropylimidazoline hydrochloride, sodium bisulfite, and sodium pyrosulfite.

5. The preparation method of the guar gum modifying and enhancing agent according to claim 1, characterized in that: The guar gum raw material is selected from at least one of natural guar gum, hydroxyethyl guar gum, hydroxypropyl guar gum, carboxymethyl guar gum, carboxymethyl hydroxypropyl guar gum, carboxymethyl hydroxyethyl guar gum, cationic guar gum, cationic hydroxypropyl guar gum, cationic hydroxyethyl guar gum and amphoteric guar gum.

6. The preparation method of the guar gum modifier and enhancer according to claim 1, characterized in that: The catalyst is selected from at least one of sulfuric acid, phosphoric acid, and p-toluenesulfonic acid; the inhibitor is selected from at least one of p-methoxyphenol, hydroquinone, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, and methylhydroquinone; and the organic unsaturated acid (anhydride) is selected from at least one of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, and itaconic acid.

7. The preparation method of the guar gum modifying and enhancing agent according to claim 1, characterized in that: The acid is selected from at least one of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, and citric acid; the cross-linking agent is selected from at least one of N,N-methylenebisacrylamide, N-hydroxymethylacrylamide, polyethylene glycol diallyl ether, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol triallyl ether, pentaerythritol triacrylate, dipentaerythritol hexaallyl ether, dipentaerythritol hexaacrylate, and 1,3,5-triacrylamide-hexahydrotriazine; the molecular weight regulator is selected from at least one of sodium hypophosphite, sodium pyrosulfite, sodium sulfite, sodium bisulfite, sodium formate, isopropyl alcohol, sodium propylene sulfonate, and sodium methyl propylene sulfonate; the terminator is selected from at least one of sodium sulfite, sodium pyrosulfite, sodium bisulfite, sodium thiosulfate, p-hydroxyanisole, and sodium ascorbate.

8. The preparation method of the guar gum modifier and enhancer according to claim 1, characterized in that: The amount of the cross-linking agent used accounts for 0.01% to 0.5% of the mass of the guar gum modified reinforcing agent.

9. A guar gum modifier and enhancer, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the guar gum modifying and enhancing agent according to claim 9 in papermaking.

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