阅读说明：本技术 一种纸张高效湿强剂的制备方法 (Preparation method of efficient wet strength agent for paper ) 是由 陈文新 杨文杰 董雪峰 于 2021-10-29 设计创作，主要内容包括：本发明涉及一种纸张高效湿强剂的制备方法,其包括以下步骤,将PAE粗品静置,分层,取上层液体经过带有过滤介质的滤芯过滤,将pH调节剂滴加至除氯滤液中,调节pH为2-4,再加入占总重量1-3%的复合型抗氧剂和占总重量1-3%的消泡剂,进行过滤处理,将滤液回收并与分层得到的下层沉淀混合,得到PAE精品,将第二份脱氯剂投入PAE精品中,并加去离子水稀释成乳液,搅拌10-15min,得到湿强剂。本发明通过两次添加脱氯剂和二次过滤处理,消耗聚酰胺环氧树脂中残余的环氧氯丙烷,最终湿强剂中的有机氯含量极低,能达到相关的质量标准,操作简易快捷。(The invention relates to a preparation method of a paper high-efficiency wet strength agent, which comprises the following steps of standing and layering a crude product of PAE, filtering an upper layer liquid through a filter element with a filter medium, dropwise adding a pH regulator into dechlorination filtrate, regulating the pH to 2-4, adding a composite antioxidant accounting for 1-3% of the total weight and a defoaming agent accounting for 1-3% of the total weight, filtering, recovering the filtrate, mixing the filtrate with a lower layer precipitate obtained by layering to obtain a refined product of PAE, adding a second part of dechlorination agent into the refined product of PAE, adding deionized water to dilute into emulsion, and stirring for 10-15min to obtain the wet strength agent. According to the invention, through twice addition of dechlorinating agent and twice filtration treatment, residual epoxy chloropropane in polyamide epoxy resin is consumed, and finally, the organic chlorine content in the wet strength agent is extremely low, so that the wet strength agent can reach the relevant quality standard, and the operation is simple and rapid.)

1. A preparation method of the paper high-efficiency wet strength agent is characterized by comprising the following steps: comprises the following steps of (a) carrying out,

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 3-4 by using a pH regulator, uniformly stirring, then putting dibasic acid into the reaction kettle, statically raising the temperature to 190 ℃ under normal pressure, carrying out dehydration polycondensation reaction for 2-4h, then adding deionized water to dilute, stir and uniformly mix, and cooling to normal temperature to obtain a polyamide polyamine prepolymer;

s2, dripping epichlorohydrin into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 30-60min, statically heating to 30-50 ℃ at normal pressure after dripping, keeping the temperature for reaction for 4-5h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 3-6, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2;

s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate;

s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 2-4, adding a composite antioxidant accounting for 1-3% of the total weight and a defoaming agent accounting for 1-3% of the total weight, oscillating at normal temperature for 40-60min, standing for 60min, filtering, recovering the filtrate, and mixing the filtrate with the lower-layer precipitate obtained by layering in S3 to obtain a PAE fine product;

s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 10-15min to obtain the wet strength agent.

2. The preparation method of the paper high-efficiency wet strength agent according to claim 1, characterized in that: in the S3, the components in the raw material of the filter medium are mixed and stirred for 10-15min in advance, the mixture is placed in a mould pressing device for mould pressing, then the mixture is sintered for 45-65min at the temperature of 200-220 ℃, and the filter medium is obtained after cooling and demoulding.

3. The preparation method of the paper high-efficiency wet strength agent according to claim 1, characterized in that: the filter medium is prepared from the following raw materials in parts by weight,

50 parts of ultra-high molecular weight polyethylene;

30-50 parts of superfine heavy calcium carbonate;

10-25 parts of silicon dioxide substrate single-layer graphene;

10-25 parts of nano titanium dioxide loaded silver ions;

5-15 parts of methoxy cinnamoyl propyl silsesquioxane silicate;

1-10 parts of a loosening agent;

15-30 parts of quartz molecular sieve.

4. The preparation method of the paper high-efficiency wet strength agent according to claim 3, characterized in that: the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand.

5. The preparation method of the paper high-efficiency wet strength agent according to claim 3, characterized in that: the loosening agent is azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid.

6. The preparation method of the paper high-efficiency wet strength agent according to claim 3, characterized in that: the quartz molecular sieve has micropores of 80nm or less.

7. The preparation method of the paper high-efficiency wet strength agent according to claim 1, characterized in that: in the step S4, the filtering process is an activated carbon adsorption process, a micro-electrolysis process, a hydrogen peroxide treatment process or a Fenton reagent treatment process.

8. The preparation method of the paper high-efficiency wet strength agent according to claim 1, characterized in that: the compound antioxidant consists of the following raw materials in parts by weight,

1.0-2.5 parts of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester;

0.5-1.5 parts of tris (nonylphenol) phosphite;

0.5-1.0 part of ditridecanol thiodipropionate.

9. The preparation method of the paper high-efficiency wet strength agent according to claim 1, characterized in that: the defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation compound of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether.

10. The preparation method of the paper high-efficiency wet strength agent according to claim 1, characterized in that: the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first part of dechlorination agent to the second part of dechlorination agent is (1-4): 1.

Technical Field

The invention relates to the technical field of papermaking materials, in particular to a preparation method of a high-efficiency wet strength agent for paper.

Background

The wet strength of paper refers to the strength of paper when meeting water or in a humid environment, and many paper products require high wet strength, and the wet strength agent can be added to improve the wet strength of paper under the conditions of wetting and the like. In recent years, polyamide epichlorohydrin (PAE) resin is a paper wet strength agent which is widely applied at present, can be used under neutral and alkaline conditions, and is a cationic polymer resin which is obtained by crosslinking long-chain polyamide polyamine through epichlorohydrin and has thermosetting property and water solubility. In the production process of the PAE type wet strength agent, as epichlorohydrin generates hydrolysis side reaction, organic chlorine 1, 3-dichloro-2-propanol (DCP), 3-chlorine-1, 2-propylene glycol (MCPD) and the like are generated, and the substances are toxic and can endanger human health. Therefore, the control of the residual organic chlorine content of the wet strength agent within the requirements is the necessary development direction of the wet strength agent.

At present, in domestic papermaking wet strength agent products with the solid content of 12.5%, the organic chlorine content is generally 1% -6%, which is higher than the residual amount of chloropropanol of international papermaking wet strength agent by more than one or even two orders of magnitude, for example, the residual amounts of 1, 3-dichloro-2-propanol in products of US5614597 and US6342580B1 are respectively below 0.1298% and 5 ppm. Moreover, most of the organic chlorine is removed in a post-treatment mode, namely, dechlorination treatment is carried out after the wet strength agent is produced, so that the product defects are easily caused, and the popularization and the application of the product are limited. For example, the post-alkali treatment of the product adopted in US6429267B1 is easy to generate salt with acid which plays a stabilizing role in resin, and is not beneficial to the popularization of the product in some fields. Therefore, there is a need to optimize the process conditions of the wet strength agent production process without any post-treatment to achieve a reduction of organochlorine in the product.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a preparation method of a high-efficiency wet strength agent for paper, which achieves the aim of reducing the content of organic chlorine in the wet strength agent.

The above object of the present invention is achieved by the following technical solutions:

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 3-4 by using a pH regulator, uniformly stirring, then putting dibasic acid into the reaction kettle, statically raising the temperature to 190 ℃ at normal pressure, carrying out dehydration polycondensation reaction for 2-4h, then adding deionized water to dilute, uniformly stirring, and cooling to normal temperature to obtain a polyamide polyamine prepolymer; s2, dripping epichlorohydrin into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 30-60min, statically heating to 30-50 ℃ at normal pressure after dripping, keeping the temperature for reaction for 4-5h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 3-6, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2; s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate; s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 2-4, adding a composite antioxidant accounting for 1-3% of the total weight and a defoaming agent accounting for 1-3% of the total weight, oscillating at normal temperature for 40-60min, standing for 60min, filtering, recovering the filtrate, and mixing the filtrate with the lower-layer precipitate obtained by layering in S3 to obtain a PAE fine product; s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 10-15min to obtain the wet strength agent.

By adopting the technical scheme, the first part of dechlorinating agent is added at the later stage of the polymerization reaction of the polyamide polyamine epichlorohydrin resin (PAE), the polyamide polyamine epichlorohydrin resin generated by the reaction can be mixed with the hydrolyzed guar gum for reaction, the residual epichlorohydrin in the polyamide epichlorohydrin resin is consumed, so that the PAE crude product has lower organic chlorine content, and the residual organic chlorine is promoted to be dissolved by the pH regulator and the deionized water; then, the organic chlorine and other low molecular impurities in the upper layer liquid can be effectively removed through secondary filtration by the S3 filter element with the filter medium and the filtration treatment of S4, and finally, the residual organic chlorine is removed again by the second part of dechlorinating agent, so that the organic chlorine content in the wet strength agent is extremely low, the relevant quality standard can be reached, and the operation is simple and rapid.

Further, in the step S3, the components in the raw material of the filter medium are mixed and stirred for 10-15min in advance, the mixture is placed in a mould pressing device for mould pressing, then the mixture is sintered for 45-65min at the temperature of 200-220 ℃, and the filter medium is obtained after cooling and demoulding.

Further, the filter medium is prepared from the following raw materials in parts by weight, 50 parts of ultra-high molecular weight polyethylene; 30-50 parts of superfine heavy calcium carbonate; 10-25 parts of silicon dioxide substrate single-layer graphene; 10-25 parts of nano titanium dioxide loaded silver ions; 5-15 parts of methoxy cinnamoyl propyl silsesquioxane silicate; 1-10 parts of a loosening agent; 15-30 parts of quartz molecular sieve.

The ultra-high molecular weight polyethylene, the ultrafine heavy calcium carbonate, the silicon dioxide-based single-crystal single-layer graphene and the quartz molecular sieve adopted by the filter medium have a strong adsorption effect on organic chlorine, and on the basis, the compatibility and porosity among the raw materials of the filter medium are increased by loading silver ions, methoxy cinnamoyl propyl silsesquioxane silicate and a bulking agent on the nano titanium dioxide, so that the organic chlorine in the supernatant can be effectively removed, and the removal rate is over 90 percent.

Further, the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand. It is preferable to use the ultra-high molecular weight polyethylene having a viscosity average molecular weight of 550-600 ten thousand, and it is preferable to use the ultra-high molecular weight polyethylene having a powder-like particle size of 170-200. mu.m.

Further, the bulking agent is an azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid. Sodium bicarbonate or ammonium bicarbonate is preferably used as the bulking agent.

Further, the quartz molecular sieve has micropores of 80nm or less. Preferably, a quartz molecular sieve with 1-2nm micropore diameter is adopted.

Further, in S4, the filtering process is an activated carbon adsorption process, a micro-electrolysis process, a hydrogen peroxide treatment process, or a Fenton reagent treatment process. Preferably, an activated carbon adsorption method is adopted, which is matched with the filtration step of the filter element with the filter medium of S3, and has better dechlorination effect.

Further, the compound antioxidant comprises the following raw materials, by weight, 1.0-2.5 parts of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester; 0.5-1.5 parts of tris (nonylphenol) phosphite; 0.5-1.0 part of ditridecanol thiodipropionate.

By adopting the formula, the processing stability and the long-acting stability of the PAE resin can be improved.

Further, the defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation product of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether. Propylene glycol polyoxypropylene ether is preferably used as a defoaming agent so as to avoid excessive bubbles generated in the shaking process and influence the preparation of the subsequent emulsion type reinforcing agent.

Further, the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first part of dechlorination agent to the second part of dechlorination agent is (1-4): 1. after the copolymerization reaction stage and the filtration treatment, the polyamide polyamine epichlorohydrin resin can be mixed with the hydrolyzed guar gum for reaction, the residual epichlorohydrin in the polyamide epoxy resin is consumed, and the final product has lower organic chlorine content and more excellent application performance.

In conclusion, the beneficial technical effects of the invention are as follows: through twice addition of dechlorinating agents and twice filtration treatment, residual epoxy chloropropane in the polyamide epoxy resin is consumed, the content of organic chlorine in the final wet strength agent is extremely low, the related quality standard can be achieved, and the operation is simple and rapid.

Detailed Description

In order to make the technical means, the creation features, the achievement purposes and the functions of the invention clearer and easier to understand, the invention is further described in the following with the specific embodiments.

Examples

Example 1: the invention discloses a preparation method of a high-efficiency wet strength agent for paper, which comprises the following steps,

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 3 by using a pH regulator, stirring uniformly, then putting dibasic acid into the reaction kettle, heating to 150 ℃ under static normal pressure, carrying out dehydration polycondensation reaction for 4.0h, then adding deionized water, diluting, stirring uniformly, and cooling to normal temperature to obtain a polyamide polyamine prepolymer;

s2, dripping epichlorohydrin into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 45min, statically heating to 35 ℃ at normal pressure after dripping, keeping the temperature for reaction for 4.0h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 3, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2;

s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate;

s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 3, adding a composite antioxidant accounting for 1% of the total weight and a defoaming agent accounting for 3% of the total weight, oscillating for 50min at normal temperature, standing for 60min, filtering, recovering the filtrate, and mixing the filtrate with the lower-layer precipitate obtained by layering in S3 to obtain a PAE fine product;

s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 10min to obtain the wet strength agent.

In S3, 50 parts of ultra-high molecular weight polyethylene, 30 parts of superfine ground calcium carbonate, 10 parts of silicon dioxide substrate single-layer graphene, 25 parts of nano titanium dioxide loaded silver ions, 5 parts of methoxy cinnamoyl propyl silsesquioxane silicate, 1 part of bulking agent and 15 parts of quartz molecular sieve are mixed and stirred for 10min in advance, placed in a mould press for mould pressing, then sintered for 45min at 200 ℃, cooled and demoulded to obtain the filter medium.

In S4, the filtration treatment is an activated carbon adsorption method, a micro-electrolysis method, a hydrogen peroxide treatment method, or a Fenton reagent treatment method. This embodiment preferably employs an activated carbon adsorption process, which has a better dechlorination effect in cooperation with the filtering step of the filter cartridge with the filtering medium of S3.

The compound antioxidant comprises the following raw materials, by weight, 1.0 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 1.0 part of tris (nonylphenol) phosphite ester and 0.5 part of ditridecyl alcohol thiodipropionate. Wherein the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand. The present embodiment preferably employs the ultra-high molecular weight polyethylene having a viscosity average molecular weight of 550-600 ten thousand, and preferably employs the ultra-high molecular weight polyethylene having a powder-like particle size of 170-200 μm. The bulking agent is azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid. This embodiment preferably employs sodium bicarbonate or ammonium bicarbonate as the bulking agent. The quartz molecular sieve has micropores of 80nm or less. The quartz molecular sieve with the pore diameter of 1-2nm is preferably adopted in the embodiment.

The defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation compound of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether. In this embodiment, propylene glycol polyoxypropylene ether is preferably used as a defoaming agent to avoid excessive bubbles generated during the shaking process, which affects the preparation of the subsequent emulsion type reinforcing agent.

In S5, the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first and second parts of dechlorination agents is 1:1.

example 2: the invention discloses a preparation method of a high-efficiency wet strength agent for paper, which comprises the following steps,

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 4 by using a pH regulator, stirring uniformly, then putting dibasic acid into the reaction kettle, heating to 160 ℃ under static normal pressure, carrying out dehydration polycondensation reaction for 3.5 hours, then adding deionized water, diluting, stirring uniformly, and cooling to normal temperature to obtain a polyamide polyamine prepolymer;

s2, dripping epichlorohydrin into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 30min, statically heating to 40 ℃ at normal pressure after dripping, keeping the temperature for reaction for 5.0h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 4, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2;

s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate;

s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 2, adding a composite antioxidant accounting for 2% of the total weight and a defoaming agent accounting for 2% of the total weight, oscillating for 45min at normal temperature, standing for 60min, filtering, recovering the filtrate, and mixing the filtrate with the lower-layer precipitate obtained by layering in S3 to obtain a PAE fine product;

s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 12min to obtain the wet strength agent.

In S3, 50 parts of ultra-high molecular weight polyethylene, 40 parts of superfine ground calcium carbonate, 15 parts of silicon dioxide substrate single-layer graphene, 15 parts of nano titanium dioxide loaded silver ions, 10 parts of methoxy cinnamoyl propyl silsesquioxane silicate, 3 parts of a bulking agent and 20 parts of a quartz molecular sieve are mixed and stirred for 11min in advance, placed in a mould pressing device for mould pressing, then sintered for 50min at 210 ℃, cooled and demoulded to obtain the filter medium.

In S4, the filtration treatment is an activated carbon adsorption method, a micro-electrolysis method, a hydrogen peroxide treatment method, or a Fenton reagent treatment method. This embodiment preferably employs an activated carbon adsorption process, which has a better dechlorination effect in cooperation with the filtering step of the filter cartridge with the filtering medium of S3.

The compound antioxidant comprises the following raw materials, by weight, 1.5 parts of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 1.5 parts of tris (nonylphenol) phosphite ester and 1.0 part of ditridecyl alcohol thiodipropionate. Wherein the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand. The present embodiment preferably employs the ultra-high molecular weight polyethylene having a viscosity average molecular weight of 550-600 ten thousand, and preferably employs the ultra-high molecular weight polyethylene having a powder-like particle size of 170-200 μm. The bulking agent is azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid. This embodiment preferably employs sodium bicarbonate or ammonium bicarbonate as the bulking agent. The quartz molecular sieve has micropores of 80nm or less. The quartz molecular sieve with the pore diameter of 1-2nm is preferably adopted in the embodiment.

The defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation compound of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether. In this embodiment, propylene glycol polyoxypropylene ether is preferably used as a defoaming agent to avoid excessive bubbles generated during the shaking process, which affects the preparation of the subsequent emulsion type reinforcing agent.

In S5, the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first and second parts of dechlorination agents is 2: 1.

example 3: the invention discloses a preparation method of a high-efficiency wet strength agent for paper, which comprises the following steps,

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 4 by using a pH regulator, stirring uniformly, then putting dibasic acid into the reaction kettle, heating to 170 ℃ under static normal pressure, carrying out dehydration polycondensation reaction for 3.0h, then adding deionized water, diluting, stirring uniformly, and cooling to normal temperature to obtain a polyamide polyamine prepolymer;

s2, dripping epoxy chloropropane into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 40min, statically heating to 45 ℃ at normal pressure after dripping, keeping the temperature for reaction for 4.5h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 5, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2;

s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate;

s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 4, adding a composite antioxidant accounting for 3% of the total weight and a defoaming agent accounting for 1% of the total weight, oscillating at normal temperature for 60min, standing for 60min, filtering, recovering the filtrate, and mixing the filtrate with the lower-layer precipitate obtained by layering in S3 to obtain a PAE fine product;

s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 13min to obtain the wet strength agent.

In S3, 50 parts of ultra-high molecular weight polyethylene, 50 parts of ultrafine ground calcium carbonate, 20 parts of silica-based single-crystal single-layer graphene, 25 parts of nano titanium dioxide-loaded silver ions, 15 parts of methoxy cinnamoyl propyl silsesquioxane silicate, 5 parts of a bulking agent and 25 parts of a quartz molecular sieve are mixed and stirred for 13min in advance, placed in a mould press for mould pressing, then sintered for 55min at 215 ℃, cooled and demoulded to obtain the filter medium.

In S4, the filtration treatment is an activated carbon adsorption method, a micro-electrolysis method, a hydrogen peroxide treatment method, or a Fenton reagent treatment method. This embodiment preferably employs an activated carbon adsorption process, which has a better dechlorination effect in cooperation with the filtering step of the filter cartridge with the filtering medium of S3.

The compound antioxidant comprises the following raw materials, by weight, 2.5 parts of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 0.5 part of tris (nonylphenol) phosphite ester and 0.7 part of ditridecyl alcohol thiodipropionate. Wherein the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand. The present embodiment preferably employs the ultra-high molecular weight polyethylene having a viscosity average molecular weight of 550-600 ten thousand, and preferably employs the ultra-high molecular weight polyethylene having a powder-like particle size of 170-200 μm. The bulking agent is azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid. This embodiment preferably employs sodium bicarbonate or ammonium bicarbonate as the bulking agent. The quartz molecular sieve has micropores of 80nm or less. The quartz molecular sieve with the pore diameter of 1-2nm is preferably adopted in the embodiment.

The defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation compound of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether. In this embodiment, propylene glycol polyoxypropylene ether is preferably used as a defoaming agent to avoid excessive bubbles generated during the shaking process, which affects the preparation of the subsequent emulsion type reinforcing agent.

In S5, the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first and second parts of dechlorination agents is 3: 1.

example 4: the invention discloses a preparation method of a high-efficiency wet strength agent for paper, which comprises the following steps,

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 3 by using a pH regulator, stirring uniformly, then putting dibasic acid into the reaction kettle, heating to 180 ℃ under static normal pressure, carrying out dehydration polycondensation reaction for 2.5h, then adding deionized water, diluting, stirring uniformly, and cooling to normal temperature to obtain a polyamide polyamine prepolymer;

s2, dripping epoxy chloropropane into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 60min, statically heating to 50 ℃ at normal pressure after dripping, keeping the temperature for reaction for 4.5h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 6, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2;

s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate;

s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 3, adding a composite antioxidant accounting for 2% of the total weight and a defoaming agent accounting for 2% of the total weight, oscillating for 45min at normal temperature, standing for 60min, filtering, recovering the filtrate, and mixing the filtrate with the lower-layer precipitate obtained by layering in S3 to obtain a PAE fine product;

s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 15min to obtain the wet strength agent.

In S3, 50 parts of ultra-high molecular weight polyethylene, 35 parts of superfine ground calcium carbonate, 25 parts of silica-based single-crystal single-layer graphene, 10 parts of nano titanium dioxide-loaded silver ions, 10 parts of methoxy cinnamoyl propyl silsesquioxane silicate, 7 parts of a bulking agent and 30 parts of a quartz molecular sieve are mixed and stirred for 14min in advance, placed in a mould pressing device for mould pressing, then sintered for 65min at 220 ℃, cooled and demoulded to obtain the filter medium.

In S4, the filtration treatment is an activated carbon adsorption method, a micro-electrolysis method, a hydrogen peroxide treatment method, or a Fenton reagent treatment method. This embodiment preferably employs an activated carbon adsorption process, which has a better dechlorination effect in cooperation with the filtering step of the filter cartridge with the filtering medium of S3.

The compound antioxidant comprises the following raw materials, by weight, 2.0 parts of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 1.0 part of tris (nonylphenol) phosphite ester and 0.8 part of ditridecyl alcohol thiodipropionate. Wherein the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand. The present embodiment preferably employs the ultra-high molecular weight polyethylene having a viscosity average molecular weight of 550-600 ten thousand, and preferably employs the ultra-high molecular weight polyethylene having a powder-like particle size of 170-200 μm. The bulking agent is azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid. This embodiment preferably employs sodium bicarbonate or ammonium bicarbonate as the bulking agent. The quartz molecular sieve has micropores of 80nm or less. The quartz molecular sieve with the pore diameter of 1-2nm is preferably adopted in the embodiment.

The defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation compound of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether. In this embodiment, propylene glycol polyoxypropylene ether is preferably used as a defoaming agent to avoid excessive bubbles generated during the shaking process, which affects the preparation of the subsequent emulsion type reinforcing agent.

In S5, the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first and second parts of dechlorination agents is 4: 1.

example 5: the invention discloses a preparation method of a high-efficiency wet strength agent for paper, which comprises the following steps,

s1, firstly putting a polyethylene polyamine monomer into a reaction kettle, then adjusting the pH of the solution to 3 by using a pH regulator, stirring uniformly, then putting dibasic acid into the reaction kettle, heating to 190 ℃ under static normal pressure, carrying out dehydration polycondensation reaction for 2.0h, then adding deionized water, diluting, stirring uniformly, and cooling to normal temperature to obtain a polyamide polyamine prepolymer;

s2, dripping epoxy chloropropane into the polyamide polyamine prepolymer obtained in S1 at normal temperature and normal pressure, dripping for 50min, statically heating to 30 ℃ at normal pressure after dripping is finished, carrying out heat preservation reaction for 4.5h, then cooling to room temperature, adding a first part of dechlorinating agent, pH regulator and deionized water to regulate the pH to 5, wherein the solid content is 25%, and obtaining a crude product of PAE; the molar ratio of the polyethylene polyamine monomer to the dibasic acid to the epichlorohydrin is 1:1: 1.2;

s3 standing and layering the PAE crude product obtained in S2, filtering the upper layer liquid through a filter element with a filter medium to remove excessive organic chlorine and other low molecular impurities in the upper layer liquid to obtain dechlorinated filtrate;

s4, dropwise adding a pH regulator into the dechlorination filtrate obtained in S3, regulating the pH to 4, adding a composite antioxidant accounting for 3% of the total weight and a defoaming agent accounting for 1% of the total weight, oscillating at normal temperature for 40min, standing for 60min, filtering, recovering the filtrate, and mixing with the lower-layer precipitate obtained in the step S3 to obtain a PAE fine product;

s5, adding the second part of dechlorinating agent into the PAE fine product, adding deionized water to dilute into emulsion, and stirring for 14min to obtain the wet strength agent.

In S3, 50 parts of ultra-high molecular weight polyethylene, 45 parts of ultra-fine heavy calcium carbonate, 10 parts of silica-based single-crystal single-layer graphene, 10 parts of nano titanium dioxide-loaded silver ions, 5 parts of methoxy cinnamoyl propyl silsesquioxane silicate, 10 parts of a bulking agent and 25 parts of a quartz molecular sieve are mixed and stirred for 15min in advance, placed in a mould pressing device for mould pressing, then sintered for 50min at 205 ℃, cooled and demoulded to obtain the filter medium.

In S4, the filtration treatment is an activated carbon adsorption method, a micro-electrolysis method, a hydrogen peroxide treatment method, or a Fenton reagent treatment method. This embodiment preferably employs an activated carbon adsorption process, which has a better dechlorination effect in cooperation with the filtering step of the filter cartridge with the filtering medium of S3.

The compound antioxidant comprises the following raw materials, by weight, 1.5 parts of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 1.7 parts of tris (nonylphenol) phosphite ester and 1.0 part of ditridecyl alcohol thiodipropionate. Wherein the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100-1000 ten thousand. The present embodiment preferably employs the ultra-high molecular weight polyethylene having a viscosity average molecular weight of 550-600 ten thousand, and preferably employs the ultra-high molecular weight polyethylene having a powder-like particle size of 170-200 μm. The bulking agent is azo compound, sodium bicarbonate, ammonium carbonate or oxalic acid. This embodiment preferably employs sodium bicarbonate or ammonium bicarbonate as the bulking agent. The quartz molecular sieve has micropores of 80nm or less. The quartz molecular sieve with the pore diameter of 1-2nm is preferably adopted in the embodiment.

The defoaming agent is glycerol polyoxypropylene ether, an organic silicon compound, a condensation compound of fatty alcohol and ethylene oxide propylene oxide or propylene glycol polyoxypropylene ether. In this embodiment, propylene glycol polyoxypropylene ether is preferably used as a defoaming agent to avoid excessive bubbles generated during the shaking process, which affects the preparation of the subsequent emulsion type reinforcing agent.

In S5, the dechlorination agent is hydrolyzed guar gum, and the weight ratio of the first and second parts of dechlorination agents is 3: 1.

performance test

The crude PAE products and the reinforcing agents of examples 1 to 5 were used as test samples, and the organochlorine content in each sample was measured, respectively, and the test results are shown in Table 1.

TABLE 1

Detecting items	Example 1	Example 2	Example 3	Example 4	Example 5
						Organic chlorine content (mug/L) in PAE crude product	3.8	3.9	4.2	4.8	4.5
The content of organic chlorine in the enhancer (μ g/L)	≤0.1	≤0.1	≤0.1	≤0.1	≤0.1

As can be seen from table 1, by using the method of the present invention, a first portion of dechlorinating agent is added at the later stage of the polymerization reaction of the polyamide polyamine epichlorohydrin resin (PAE), the polyamide polyamine epichlorohydrin resin generated by the reaction can be mixed with the hydrolyzed guar gum to react, the residual epichlorohydrin in the polyamide epichlorohydrin resin is consumed, so that the PAE crude product has a lower organic chloride content, and the residual organic chloride is promoted to be dissolved by the pH regulator and the deionized water; then, the organic chlorine and other low molecular impurities in the upper layer liquid can be effectively removed through secondary filtration by the S3 filter element with the filter medium and the filtration treatment of S4, and finally, the residual organic chlorine is removed again by the second part of dechlorinating agent, so that the organic chlorine content in the wet strength agent is extremely low, the relevant quality standard can be reached, and the operation is simple and rapid.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.