Study On Preparation And Properties Of Environmental Protection Type Wet Strength Agent

With the improvement of living standards,the requirements for the paper get higher and higher.On the other hand,beasuse of lack of resources,we hope to save resources by increasing the proportion of straw,which will inevitably decrease the paper quality,especially the strength.Polyamide polyamine epichlorohydrin(PAE)is widely applied as wet strength agent in papermaking industry,but it contains high content of carcinogen-organic chlorine,which is harmful to the human body and environment.Therefore developing new efficient environment-friendly wet strength agent is the research direction of papermaking workers in the future.The research contents are as follows:A novel wet strength agent PAEP was prepared through chemical modification of polyamide-polyamine epichlorohgdrin(PAE)resin with polyvinyl alcohol(PVA).PAEP/organo boron composite wet strength agent was also introduced in the papermaking process to increase the cross-linking among fibers.The corresponding structure and properties were characterized by IR,SEM,Zeta potential analysis and TGA.The adsorption behavior of PAEP in fiber was investigated,as well as the effects of PAE,PAEP and PAEP-organo boron dosage on the wet strength of paper.It was found that the adsorption amount of PAEP in fiber increased from 2.33 mg/g to 8.14 mg/g with the increase of PAEP dosage from 2.5 mg/g to 30 mg/g,whereas the adsorption efficiency decreased from 93.20% to 27.13%.In comparison with PAE,the thermal degradation residue of papers treated with PAEP and PAEP-organo boron increased by 122.67% and 269.60%,respectively.The dry,wet tensile index increased by 22.66% and 79.46% when the organo boron content in PAEP-organo boron was 50%.And the retention rate of tensile index increased by 46.35%.Compared with cationic starch,the PAEP-organo boron wet strength agent was also endowed with better strengthening efficiency.The introduction of polyvinyl alcohol in the reaction process can be further cross-linked with PAE,which ccould improve the wet strength,and reduce the amount of residual organic chlorine by reacting with chloropropanols.A novel cationic polyvinyl alcohol(GQPVA)grafted quaternary ammonium was prepared through chemical modification of3-Chloro-2-hydroxypropyltrimethyl ammonium chloride and glutaraldehyde with polyvinyl alcohol.GQPVA/PAE composite wet strength agent was also introduced in the papermaking process to increase the cross-linking among fibers.The corresponding structure were characterized by IR.The nitrogen content of QPVA characterized by element analyzer was investigated,as well as the effect of GQPVA dosage on the strength of paper.In comparison with PAE,it was found that the dry,wet tensile index increased by 11.8% and 6.88%,respectively,and the tensile index retention rate increased by 6.94%.The tearing index and folding resistance degree increased by 8.27% and 26.2%,respectively.The results of SEM showed that the addition of GQPVA/PAE increased the chemical bond between fiber and resin,forming a interpenetrating network structure of high strength in the paper.Moreover,the fiber morphology was analyzed by fiber morphology analyzer.Compared with the blank sample,fine fiber content of PAE and GQPVA/PAE paper improved by 234.4% and 236.1% on the point of length distribution.But on the point of area distribution,they improved by139.6% and 145.8%,respectively.Combined the advantages of PAE,cationic polyacrylamide(GPAM)modified by KH570,and interpenetrating polymer network,a novel interpenetrating polymer network(GPAM-PAE)was prepared through free radical copolymerization method of acrylamide(AM),Diallyl dimethyl ammonium chloride(DAD)and γ-methacryloxypropyltrimethoxysilane(KH570),with polyamine epichlorohydrin resin(PAE)as reaction medium and glyoxal(GO)as crosslinking agent.GPAM-PAE composite wet strength agent was also introduced in the papermaking process to increase the cross-linking among fibers.The results showed that the optimum conditions were as follows: w(AM): w(DAD): w(GO): w(KH570)=100:25:1:0.2,reaction time was 3 hours and reaction temperature was 70℃.When PAE content is 48% in GPAM-PAE,the dry and wet tensile index was 17.2 N·m/g and 81.2 N·m/g,respectively.At the same time,tensile index retention rate and tearing index were 23.3% and 15.6mN·m~2/g,and the folding resistance degree and the bursting index were 2705 n and 8.19 k Pa·m~2/g.In comparison with PAE,the wet tensile index,tensile index retention rate,tearing index,folding resistance degree and bursting index increased by 8.17%,16.5%,8.33%,27.4%,and 15.7%,respectively.The content of organic chlorine decreased from 0.811% to 0.079%.With PAE content in the range from 40% to 70%,Cobb60 significantly reduced and water resistance increased.From the surface SEM of paper fibers,the fracture SEM of paper and fine fiber reseach showed that the wet strength performance of GPAM-PAE composite was superior to that of pure PAE.Paper surface almost had no obvious gap and the fiber cross-section was neat,and the higher crosslinking degree between fiber and resin is favorable to improve the retention of fiber fines and particulate filler.The addition of wet strength agent is advantageous to enhance the performance of paper and improve the utilization rate of raw materials.