Stickies Control And Removal In Recycled Pulp By Attapulgite

Shortages of papermaking raw materials have been much to the fore at home and abroad.The recycling of waste paper has brought huge economic and environmental benefits in reducing pollution,improving environment,saving resources and energy.However,the stickies in the recycled paper become a new difficult problem to be solved.Attapulgite is an inexpensive inorganic mineral filler,and it is abundant in China.Attapulgite has good chemical stability and strong adsorption capacity.In this paper,attapulgite was used as a sticky controller,while talc and calcium carbonate are the control samples.The adsorption and control effect of attapulgite on hot melt adhesive,pressure sensitive adhesive,cationic starch and other stickies in pulp were studied.Meanwhile,the physicochemical properties and its effect on paper making were studied.The research provides certain theoretical basis for industrial application.It also provides a new method for the removal and control of sticky in waste paper making.The results of the experiment are as follows:Two different hot melt adhesives were used in the experiment.With the content of 2%hot melt adhesive,the dose of attapulgite 5%,the adhesive weight is 57.4%and 46.7%less than that of blank samples.With the 5%hot melt adhesive,the 5%attapulgite dosage,the adhesive weight is 25.8%and 25.9%less than that of blank.As for 5%content of hot melt adhesive to the recycled pulp,the attached amount of the hot melt adhesive on the foil was 5.5 times higher than that of the softwood pulp.After loading 5%attapulgite,the attached amount of the hot melt adhesive on the foil decreased by 32.3%.Research showed that the adsorbation effect of attapulgite on the pressure sensitive adhesive model is very good.After adding the attapulgite with smaller average particle size in the pulp,the retention rate of pressure sensitive adhesive is nearly 100%.The better dosage of the attapulgite is 10%to the pulp.The cationic polymer is helpful to the adsorption of pressure sensitive adhesive by attapulgite.The strength of paper increased a lot with pressure sensitive adhesive.It was found that all the strength properties of the treated paper were lower than those untreated.Attapulgite has good adsorption effect on pressure sensitive adhesive and high retention rate,but its paper strength is lower than that with talc and calcium carbonate.The maximum cationic starch adsorption amount on attapulgite is up to 1763mg/g,however,the maximum cationic starch adsorption amount on talc is only up to 461mg/g,and the cationic starch adsorption on calcium carbonate is 574mg/g.After adding attapulgite in the pulp,the adsorption of cationic starch was significantly higher than that of talc and calcium carbonate.Especially when the concentration of cationic starch reaches 0.1%of high concentration,the adsorption capacity of attapulgite to cationic starch is more than 6.84mg/g of calcium carbonate,more than 19.32mg/g of talc.The average particle size of the attapulgite used in this paper is similar with that of talc and calcium carbonate,it's between 1.2~3?m.However,the specific surface area of attapulgite is much bigger than that of talc and calcium carbonate.The specific surface area of attapulgite is 143.023m~2/g,talc is 3.467m~2/g,and calcium carbonate is 7.790m~2/g.The SEM image showed that attapulgite is composed of many slender rod-like crystals.Thermogravimetric analysis showed that the weight loss of attapulgite with smaller particle size was obvious bigger than others.The specific surface area of attapulgite is the largest,and there are more channels in the particles,which are favorable for adsorption.In a word,the remove and adsorption capacity of stickies on attapulgite is closely related to the specific surface area and its unique crystal form.The wear value of attapulgite is somewhat high than other filler.When the dosage is high,the wear problem of the forming wire should be considered.But the wear value of attapulgite is significantly low when the particle size is small.To sum up,adding attapulgite is an effective means of adhesive control in waste paper making,and it has good adsorption effect on hot melt adhesive,pressure sensitive adhesive and starch adhesive.Compared with other fillers,the retention rate is high and the strength of paper is good.