Preparation Of High Barrier Material-Vinylidene Chloride Copolymer Latex And Its Application On Paper Based Packing Material

With the improvement of people's consciousness of environment protection, green packing material has become the main trend for the packing industry. Paper is a vital important in green packing material. The coated polyvinylidene chloride (PVDC) can improve the properties of paper packing. The subject of the paper is to synthesize PVDC copolymer for coating. The effects of the reacting factors such as the choice and amount of emulsifiers, the choice and amount of initiator, the polymerization temperature, the pH value and the doze of VDC in the monomer were researched. Based on the above result, the superion recipes have been developed for preparing different system of PVDC copolymer emulsion with high gas barrier but different properties. In the research, the synthesis PVDC copolymer emulsions were apply to paper. The results of the research are as following:1. For the synthesis of PVDC, the optimai reaction conditions are the follows: the emulsifier A and OP-10 mixture was choiced as emulsifier and their composition was define as 3:1,and its amount accounted for 3.5%, the redox system was K2S2O8/NaHSO3 defined as 2:1 was choiced and their amount is 0.8%(based on monomer), the ratio of VDC to MA monomer is 90:10, the reaction temperature is 50%, pH value is 6. On the above conditions, PVDC copolymer emulsion with high stability and excellent film-forming ability was synthesed and its coated film has high gas barrier.2. Based on the molecular and Tg design, the feasibility of flexible production was predicted. Under the optimal conditions of pH value, polymerization temperature, amount of initiator and emulsifiers, five copolymer systems of VDC-MMA, VDC-BA, VDC-MMA-AN-AA, VDC-BA-AN-AA and VDC-MMA-AN were synthesized, their coated films have with high gas barrier and stable properties. The results also show that the adhesivity of the latter three copolymer are better than the former two, buttheir barrier were impaired.3. By IR analysis, the structure of PVDC copolymers were analyzed. The results show that, the feature absorption peaks of the copolymer monomers were existed on the IR spectrum, and which indicated the copolymer monomers were enter into themolecular chain of the PVDC-Acr copolymer4. DSC was used to analyse the glass-transition temperature Tg and fusion points Tm of the PVDC-Acr copolymes. The results show that Tg of the PVDC-Acr copolymer were very low. Coating experiments confirm that all the PVDC-Acr copolymer can form film under ambient temperature. The results also show that Tm of the PVDC-Acr copolymers are lower the PVDC homopolymer.5. X-ray wide-angle diffraction was used to analyze the crystallinity of the VDC-Acrcopolymer. The results show that the crystallinity of all the polymers are very high, which is profitable to their barrier properties.6. In the applying experiment, the Kraft paper, initial dish paper sheet and molding paper dish were coated by PVDC emulsions. The results show that the barrier and heat-seal properties of the coated paper are excellent, and the physical properties were improved.