Synthesis And Mechanism Of Cationic Self-crosslinking Amide Copolymer Paper Strengthening Agent

At present,the demand for high-performance paper continues to increase,which is in line with the needs of people's living standards.The internationalization of China's paper industry is hindered.Because the traditional paper moisturizing agent(PAE)produces organic chlorine that is harmful to the human body and the environment.At the same time,PAE has a poor effect on increasing the dry strength of paper.So high-efficiency and environmentally friendly paper enhancers have become a key research project in the industry.The main research contents of this topic are as follows:1.Self-crosslinking cationic acrylamide copolymer(G-CPAM)was prepared by aqueous solution copolymerization method with methacryloxyethyl trimethylammonium chloride(DMC)as the cationic monomer,glycidyl methacrylate(GMA)as the crosslinking monomer,and acrylamide(AM)as main monomer.The structure and stability of G-CPAM were characterized by Fourier Infrared Spectroscopy(FTIR)and solution stability tests.The dosage of DMC and GMA have been discussed as influencing factors on the performance of G-CPAM and the physical properties of the paper after sizing.The mechanism of self-crosslinking of G-CPAM and paper performance enhancement has been studied through thermal weight loss analyzer(TGA),X-ray photoelectron spectroscopy(XPS)and FTIR tests before and after paper sizing.The results show that cross-linkable epoxy cationic polyacrylamide is prepared with the dosage of DMC is 20 wt%,GMA is 13 wt%,which has an average particle size of 176.90 nm,a viscosity of 143 mPa·s,and a molecular weight of 63204.And it exists stably at 150?.The dry and wet tensile index of the paper sized by 1.6 wt%G-CPAM is 58.29 N·m/g and 17.75 N·m/g,the ring compressive strength index is 11.10 N·m/g,and the tearing index is 12.41 mN·m2/g,which is an increase of 86.53%,404.86%,77.6%,and 27.15%respectively compared with the base paper.These show that G-CPAM can significantly improve the wet strength of paper and the dry strength of paper due to its good retention,strong chemical cross-linking and hydrogen bonding force with paper fibers.It can be used as a new and efficient dry/wet strength agent due to it does not contain organochlorine compounds.2.Polyamide intermediates were synthesized into adipic acid(AA)and diethylene tria mine(DETA).P-PAE resin was epoxidized by epichlorohydrin and intermediate base chains under low-temperature alkaline conditions,and then remains.The organochlorine is absorbed by high-activity polyethylenei mine and adjusted to acid storage.The structure and stability of P-PAE were characterized by infrared spectroscopy test(FTIR)and solution stability test.The dosage of ECH and PEI have been discussed as influencing factors on the residual organic chlorine content in the resin,the performance of P-PAE and the physical properties of the paper after sizing.And it was deter mined that the optimal amount of P-PAE added by the Zeta potential test of the pulp before and after adding wet strength agent.The mechanism of effect of P-PAE on paper performance has been studied through thermal weight loss analyzer(TGA),scanning electron microscope(SEM)and FTIR tests before and after paper sizing.The results showed that P-PAE resin is prepared with AA,DETA and ECH at a dosage of 1:1.05:0.9,and the amount of PEI added was 10 wt%of the intermediate.P-PAE has good stability and will not dela minate within half a year at room temperature,and it exists stably at 150?.The content of organic chlorine in P-PAE is 0.56%,which meets national standards.The paper with the best physical properties is obtained by sizing with the absolute dry fiber 1.6wt%P-PAE.The dry and wet stretch indexes of paper are 53.24 N·m/g and 19.95 N·m/g,the compressive strength index of the ring is 11.35 N·m/g and the tear index is 12.84 mN·m2/g,which are increased by 70.36%,448.88%,84.48%and 31.56%compared with the base paper,respectively.The physical properties of the paper have been significantly improved.3.G-CPAM/P-PAE composite wet strength agent was prepared by adjusting the blending ratio of G-CPAM and P-PAE resin.The best ratio was deter mined by testing the viscosity and stability of the blended product and the physical properties of the paper after sizing.The results showed that the paper has the best physical properties which is sized by the G-CPAM/P-PAE composite wet strength agent with the blending ratio of G-CPAM and P-PAE of 4:6.The tensile index is 57.69 N·m/g,the wet tensile index is 20.64 N·m/g,and the tearing index is 12.96 mN·m2/g.Compared with the single-component P-PAE sizing paper,they have respectively increased by 8.36%,5%and 0.9%,and the ring pressure index is 11.28 N·m/g.In general,the sizing paper not only has excellent moisture-enhancing performance,but also has obvious improvement in dry-strength performance.It is an environmentally friendly and efficient composite paper dry/wet-strength agent.