Development Of Water-soluble Acrylate PSA

The increasing use of recycled paper as stock in modern paper industry has brought more and more "stickles" problems, which badly affect the papermaking process. As one important source of "stickies", pressure sensitive adhesive stapes (PSAs) in recycled paper seriously influence papermaking process. So developing novel PSA not forming "stickies" is very important to modern paper industry. In this paper one water-soluble acrylate PSA not forming "stickies" in papermaking has been synthesized by emulsion polymerization technique. Main results have been obtained as followings:1. The emulsion polymerization will be remarkably influenced by the use level of the initiator and the emulsifier, by the reaction temperature and by the reaction time. With the increasing of the use level of the emulsifier, the polymerization rate and electrolyte stability of the polymer emulsion will increase; the initial adhesive and the water-solubility of the product will decrease; the shear strength of the product will first increase, and then decrease; the conversion of the reaction almost keep the same. When adopting 0.8% as the use level of initiator and 80掳C as the temperature of reaction, the emulsion polymerization in this experiment will be finished in two hours.2. The performance of the product is mainly influenced by the proportionality of different monomers, by the polymerization degree and by the neutralizing degree. With the increasing of the ratio of the hard monomers, the water-solubility and shear strength of the product will increase; the initial adhesion of the product will decrease. In order to obtain water-soluble products, enough amounts of hard monomers are necessary, and the value will drop with the increasing of the modifying agent. The changing of the modifying agent can effectively control the polymerization degree of the product, so can the performance of products. Increasing the use level of the modifying agent will cut down the shear strength and improve the water-solubility of the product, especially when the value being changed from 0 to 0.25%. The primary adhesive of the product is almost not influenced by the change of the use level of the modifying agent. The water-solubility of the product can be remarkably improved by the neutralizing of the polymer emulsion with ammonia water.3. The Z series is an effective tackifier to acrylate PSA.Z-3 that has a higher molecular weight is the best one of the Z series. The preferable use level of the Z-3 is from 10% to 15 %( W).4. As one ionic-crosslinking agent, A12 (SO4)3 can effectively improve the shear strength of the PSA. The ionic-crosslinking is not influenced by the temperature, but in some extent is influenced by the neutralization degree of the polymer emulsion. The ionic-crosslinking can not take place when the degree of the neutralization is at about 75%. The use level of the ionic-crosslinking agent is mainly limited by the electrolyte stability of the polymer emulsion.5. As one self-crosslinking agent, N-methylol methacrylamide can improve the shear strength of the PSA remarkably. The temperature and the neutralization degree of polymer emulsion are two factors that remarkably influence the self-crosslinking. The optimum temperature to the self-crosslinking is from 120掳C to 130掳C. In order to achieve enough self-crosslinking, one lower neutralization degree should be adopted. The use level of the self-crosslinking agent is mainly limited by the demands to water-solubility of the product.