微发泡过程装置设计及过程研究
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摘要
聚合物微发泡注塑成型技术研究和应用方面面临的主要问题是泡孔尺寸、泡孔分布均匀性、发泡制品表面质量控制工艺及相关微发泡机理的研究,而对微发泡过程及相关工艺的研究是解决上述问题的切入点。
二次开模微发泡成型工艺和松退微发泡成型工艺虽然都能制备微发泡聚合物材料,但这两种工艺在发泡量控制、工艺稳定性等方面还存在很多不足和难题。本文在以上两种成型工艺基础上,设计加工了变容积释压仓微发泡过程装置。利用该装置重点研究了型腔体积、反压力、装置温度和释压体积等工艺对微发泡行为的影响。
研究结果表明:型腔体积的增大为发泡体系的泡孔成核和长大创造了有利的条件,导致发泡体系自由发泡过程的发生。随着型腔体积增大,微发泡行为逐渐明显,泡孔形核数增多,泡孔孔径增大。注塑过程中,发泡体系受到的反压力能有效抑制自由发泡过程的发生,降低自由发泡程度。释压工艺有利于发泡体系泡孔形核和长大。随释压体积的增加,泡孔形核数和尺寸增大,样品密度降低。通过不同释压过程的控制,可制备出不同发泡量的微发泡样品。对于未发泡的材料,装置温度的改变没有改变发泡体系的发泡行为,而对于已发泡的材料,装置温度的升高导致泡孔孔径增大以及更多并泡现象的发生。装置温度的升高可以改善微孔聚合物材料表面质量。本文通过对化学法注塑微发泡成型工艺过程的可控性及机理研究,对发泡定量工艺控制以及注塑成型装备的研制具有一定的指导意义。
The focused problem of the research and the application of the injection molding technology for the microcellular foam plastics manufacture were the control on the micro cell size, the cell distribution, the quality of the product and the development of the injection molding equipment, which would be solved through the research on the microcellular foaming process and mechanics.
The second-open mold and the retreat mold technology could be used to prepare the microcellular foam plastics. But both the two technologies had many deficiencies and problem in the control of the foaming amount and the process stability. In this paper, the pressure releasing device of alterable cavity volume for the microcellular foaming process was designed and processed, based on the second-open mold and the retreat mold technology, and the cavity volume, the reverse pressure, the pressure-releasing volume and the temperature of the device on the microcellular foaming behavior were studied by this device.
The results showed that the increase of the cavity volume had created the favorable conditions for the nucleation and growth of the micro cell in polymer matrix, and the induced free foaming process happened. As the cavity volume increasing, the microcellular foaming behavior was gradually evident, the amount of the micro cell increased and the cell size enlarged. The reverse pressure acting on the microcellular foaming system could inhibit efficiently the free foaming process and decreased its free foaming level. The pressure-releasing process was beneficial to the nucleation and the growth of the micro cell in the foaming system. The nucleation amount and cell size increased as the pressure-releasing volume augmented, but the density of the microcellular sample decreased. Through the control with different pressure-releasing process, the microcellular foam samples with different foaming amount could be prepared. The alternation of the device temperature had no influence on foaming behavior of the un-foamed system, and the increase of the device temperature induced larger cell size and more occurrence of the cell incorporation in the foamed system. The increase of the device temperature could improve the surface quality of the microcellular foam plastics. The research on the controllability and the mechanics of the chemical injection molding process in this paper was instructional for the quantitative control on the foaming amount and the development of the injection molding equipment.
二次开模微发泡成型工艺和松退微发泡成型工艺虽然都能制备微发泡聚合物材料,但这两种工艺在发泡量控制、工艺稳定性等方面还存在很多不足和难题。本文在以上两种成型工艺基础上,设计加工了变容积释压仓微发泡过程装置。利用该装置重点研究了型腔体积、反压力、装置温度和释压体积等工艺对微发泡行为的影响。
研究结果表明:型腔体积的增大为发泡体系的泡孔成核和长大创造了有利的条件,导致发泡体系自由发泡过程的发生。随着型腔体积增大,微发泡行为逐渐明显,泡孔形核数增多,泡孔孔径增大。注塑过程中,发泡体系受到的反压力能有效抑制自由发泡过程的发生,降低自由发泡程度。释压工艺有利于发泡体系泡孔形核和长大。随释压体积的增加,泡孔形核数和尺寸增大,样品密度降低。通过不同释压过程的控制,可制备出不同发泡量的微发泡样品。对于未发泡的材料,装置温度的改变没有改变发泡体系的发泡行为,而对于已发泡的材料,装置温度的升高导致泡孔孔径增大以及更多并泡现象的发生。装置温度的升高可以改善微孔聚合物材料表面质量。本文通过对化学法注塑微发泡成型工艺过程的可控性及机理研究,对发泡定量工艺控制以及注塑成型装备的研制具有一定的指导意义。
The focused problem of the research and the application of the injection molding technology for the microcellular foam plastics manufacture were the control on the micro cell size, the cell distribution, the quality of the product and the development of the injection molding equipment, which would be solved through the research on the microcellular foaming process and mechanics.
The second-open mold and the retreat mold technology could be used to prepare the microcellular foam plastics. But both the two technologies had many deficiencies and problem in the control of the foaming amount and the process stability. In this paper, the pressure releasing device of alterable cavity volume for the microcellular foaming process was designed and processed, based on the second-open mold and the retreat mold technology, and the cavity volume, the reverse pressure, the pressure-releasing volume and the temperature of the device on the microcellular foaming behavior were studied by this device.
The results showed that the increase of the cavity volume had created the favorable conditions for the nucleation and growth of the micro cell in polymer matrix, and the induced free foaming process happened. As the cavity volume increasing, the microcellular foaming behavior was gradually evident, the amount of the micro cell increased and the cell size enlarged. The reverse pressure acting on the microcellular foaming system could inhibit efficiently the free foaming process and decreased its free foaming level. The pressure-releasing process was beneficial to the nucleation and the growth of the micro cell in the foaming system. The nucleation amount and cell size increased as the pressure-releasing volume augmented, but the density of the microcellular sample decreased. Through the control with different pressure-releasing process, the microcellular foam samples with different foaming amount could be prepared. The alternation of the device temperature had no influence on foaming behavior of the un-foamed system, and the increase of the device temperature induced larger cell size and more occurrence of the cell incorporation in the foamed system. The increase of the device temperature could improve the surface quality of the microcellular foam plastics. The research on the controllability and the mechanics of the chemical injection molding process in this paper was instructional for the quantitative control on the foaming amount and the development of the injection molding equipment.
引文
[1]张玉霞,王向东.微孔塑料发泡技术[J].现代塑料加工应用,2002,14(2):21
[2]J.E.Martini,F.A.Waldman,N.P.Suh.Production and analysis of microcellular thermoplastics foams[J].Society of Plastics Engineers Technical Papers,1982,28:674-676.
[3]周南桥.微孔塑料成型技术[J].塑料助剂,2005,4(52):31-35
[4]蔡宏国.塑料用化学发泡剂[J].现代塑料加工应用.2001,13(4):46
[5]张旭锋,王澜.发泡聚丙烯材料的研究进展[J].广东塑料,2005,133(8):53-56
[6]M.Blander,J.L.Katz.Bubble nucleation in liquids[J].AICHE.1975,21(5):833-848
[7]J.H.Han.D.H.Han.Bubble nucleation in polymeric liquids Ⅱ:theoretical consideration[J].Polymer Science,Part B:Polymer Physics,1990,28(5):743-761
[8]J.S.Colton,N.P.Suh.The nucleation of microcellular thermoplastic foam with additives:Part Ⅰ:theoretical consideration[J].Polym Eng&Sci,1987,27:485-492
[9]J.S.Colton,N.P.Suh.The nuclcation of microcellular thermoplastic foam with additives:Part Ⅱ:experimentalresults and discussion[J].Polym Eng&Sci,1987,27:500-509
[10]C.B.Park,D.F.Baldwin,N.P.Suh.Effect of the pressure drop rate on cell nucleation in continuous processing of microcellular polymers[J].Polym Eng&Sci,1995,35:432
[11]D.F.Baldwin,C.B.Park,N.P Suh.An Extrusion system for the processing of microcellular polymer sheets:shaping and cell growth control[J].Polym Eng&Sci,1996,36:1425
[12]C.W.Stewart.Nucleation and growth of bubbles in elastomers[J].Polym Eng&Sci:Part A-2,1970,8:937-955
[13]S.K.Goel,E.Beckman.Generation of microcellular polymeric foams using supercritical carbon dioxide Ⅰ:effect of pressure and temperature on nucleation[J].Polym Eng&Sci,1994,34:1137-1147
[14]S.K.Goel,E.Beckman.Generation of microcellular polymeric foams using supercritical carbon dioxide Ⅱ:cell growth and skin formation[J].Polym Eng&Sci,1994,34,1148-1156
[15]J.S.Colton.Making microcellular foams from crystalline polymers[J].Polym Eng&Sci,1988,44:53-55
[16]S.T.Lee.N.S.Ramesh.Gas loss during foam sheet formation[J].Society of Plastics Engineers Technical Papers,1995,41:2217-2224
[17]A.H.Behravesh,C.B.Park,L.K.Cheung.Extrusion of polypropylene foams with hydrocerol and isopentane[J].Vinyl and Additive Technology,1996,2:349-357
[18]S.T.Lee.Shear effects on thermoplastic foam nucleation[J].Polym Eng&Sci,1993,33:418- 422
[19]S.T.Lee.More experiments on thermoplastic foam nucleation[J].Society of Plastics Engineers Technical Papers,1994,40:1992-1997
[20]C.A.Villamizar,C.D.Han.Studies on structural foam processing II:bubble dynamics in foam injection molding[J].Polym Eng&Sci,1978,18:699-710
[21]M.Shimoda,M.Tanigaki,M.Oshima.Foams[M].New York:CRC Press,2000.91
[22]N.S.Ramesh.Foam extrusion:principles and practice[M].New York:CRC Press,2000.723
[23]何亚东.开孔型聚合物微发泡材料研究进展[J].塑料,2003,32(6):40
[24]何亚东.聚合物微发泡材料制备技术理论研究进展[J].塑料,2004,33(3):8
[25]H.E.Naguib,C.B.Park.U.Panzer.Strategies for achieving ultra low-density polypropylene foams[J].Polym Eng&Sci,2002,42(7):1481-1492
[26]邓小珍,柳和生.微孔发泡塑料的制备方法[J].轻工机械,2006,24(2):16-19
[27]孙洲渝,吴智华.微孔泡沫塑料技术进展[J].中国塑料,2001,15(7):8
[28]J.H.Han,C.D.Han.A study of bubble nucleation in a mixture of molten polymer and volatile liquid in shear flow field[J].Polym Eng&Sci,1988,28(24):1616-1627
[293 V.Kumar,N.P.Suh.A process for making microcellular thermoplastic parties[J].Polym Eng&Sci,1990,30(20):1323-1329
[30]J.E.Martini,N.P.Sun,F.A.Waldma.Microcelluar closed cell foam and their method of manufacture [P].US Patent:4473665,1984
[31]牟文杰,吴舜英.微孔泡沫塑料成型研究进展[J].中国塑料,2002,16(65):7
[32]N.S.Ramesh.Heterogeneous nucleation of microcellular foams assisted by the survival of microvoids in polymers containing low glass transition particles Part Ⅰ:mathematical modeling and numerical simulation[J].Polym Eng&Sci,1994,34(22):1685-1697
[33]Doroudiani.Effect of the crystallinity and morphology on the microcellular foam structure of semicrystalline[J].Polym Eng&Sci,1996,36(21):2645-2662
[34]D.F.Baldwin,C.B.Park,N.P.Sun.Super microcellular foamed plastics[P].US Patent,5334 356,1994.
[35]N.S.Ramesh.Numerical and experimental studies of bubble growth during the microcellular foaming process[J].Polym Eng&Sci,1991,31(23):16517
[36]李从威,周南桥,王全新.微孔发泡注射成型设备及技术研究进展[J].工程塑料应用,2008.36(10):76-79
[37]何继敏.新型聚合物发泡材料及技术[M].北京:化学工业出版社,2008,335-360
[38]杨卫民,丁玉梅,谢鹏程.注射成型新技术[M].北京:化学工业出版社,2008,298-300
[39]凯尔文T.奥卡莫特著,张玉霞泽.微孔塑料成形技术[M].北京:化学工业出版社,2004,187-190
[40]张纯,罗筑,何力.二次开模注射成型微孔发泡PP工艺及其性能研究[J].中国塑料,2005.19(8):67-68
[2]J.E.Martini,F.A.Waldman,N.P.Suh.Production and analysis of microcellular thermoplastics foams[J].Society of Plastics Engineers Technical Papers,1982,28:674-676.
[3]周南桥.微孔塑料成型技术[J].塑料助剂,2005,4(52):31-35
[4]蔡宏国.塑料用化学发泡剂[J].现代塑料加工应用.2001,13(4):46
[5]张旭锋,王澜.发泡聚丙烯材料的研究进展[J].广东塑料,2005,133(8):53-56
[6]M.Blander,J.L.Katz.Bubble nucleation in liquids[J].AICHE.1975,21(5):833-848
[7]J.H.Han.D.H.Han.Bubble nucleation in polymeric liquids Ⅱ:theoretical consideration[J].Polymer Science,Part B:Polymer Physics,1990,28(5):743-761
[8]J.S.Colton,N.P.Suh.The nucleation of microcellular thermoplastic foam with additives:Part Ⅰ:theoretical consideration[J].Polym Eng&Sci,1987,27:485-492
[9]J.S.Colton,N.P.Suh.The nuclcation of microcellular thermoplastic foam with additives:Part Ⅱ:experimentalresults and discussion[J].Polym Eng&Sci,1987,27:500-509
[10]C.B.Park,D.F.Baldwin,N.P.Suh.Effect of the pressure drop rate on cell nucleation in continuous processing of microcellular polymers[J].Polym Eng&Sci,1995,35:432
[11]D.F.Baldwin,C.B.Park,N.P Suh.An Extrusion system for the processing of microcellular polymer sheets:shaping and cell growth control[J].Polym Eng&Sci,1996,36:1425
[12]C.W.Stewart.Nucleation and growth of bubbles in elastomers[J].Polym Eng&Sci:Part A-2,1970,8:937-955
[13]S.K.Goel,E.Beckman.Generation of microcellular polymeric foams using supercritical carbon dioxide Ⅰ:effect of pressure and temperature on nucleation[J].Polym Eng&Sci,1994,34:1137-1147
[14]S.K.Goel,E.Beckman.Generation of microcellular polymeric foams using supercritical carbon dioxide Ⅱ:cell growth and skin formation[J].Polym Eng&Sci,1994,34,1148-1156
[15]J.S.Colton.Making microcellular foams from crystalline polymers[J].Polym Eng&Sci,1988,44:53-55
[16]S.T.Lee.N.S.Ramesh.Gas loss during foam sheet formation[J].Society of Plastics Engineers Technical Papers,1995,41:2217-2224
[17]A.H.Behravesh,C.B.Park,L.K.Cheung.Extrusion of polypropylene foams with hydrocerol and isopentane[J].Vinyl and Additive Technology,1996,2:349-357
[18]S.T.Lee.Shear effects on thermoplastic foam nucleation[J].Polym Eng&Sci,1993,33:418- 422
[19]S.T.Lee.More experiments on thermoplastic foam nucleation[J].Society of Plastics Engineers Technical Papers,1994,40:1992-1997
[20]C.A.Villamizar,C.D.Han.Studies on structural foam processing II:bubble dynamics in foam injection molding[J].Polym Eng&Sci,1978,18:699-710
[21]M.Shimoda,M.Tanigaki,M.Oshima.Foams[M].New York:CRC Press,2000.91
[22]N.S.Ramesh.Foam extrusion:principles and practice[M].New York:CRC Press,2000.723
[23]何亚东.开孔型聚合物微发泡材料研究进展[J].塑料,2003,32(6):40
[24]何亚东.聚合物微发泡材料制备技术理论研究进展[J].塑料,2004,33(3):8
[25]H.E.Naguib,C.B.Park.U.Panzer.Strategies for achieving ultra low-density polypropylene foams[J].Polym Eng&Sci,2002,42(7):1481-1492
[26]邓小珍,柳和生.微孔发泡塑料的制备方法[J].轻工机械,2006,24(2):16-19
[27]孙洲渝,吴智华.微孔泡沫塑料技术进展[J].中国塑料,2001,15(7):8
[28]J.H.Han,C.D.Han.A study of bubble nucleation in a mixture of molten polymer and volatile liquid in shear flow field[J].Polym Eng&Sci,1988,28(24):1616-1627
[293 V.Kumar,N.P.Suh.A process for making microcellular thermoplastic parties[J].Polym Eng&Sci,1990,30(20):1323-1329
[30]J.E.Martini,N.P.Sun,F.A.Waldma.Microcelluar closed cell foam and their method of manufacture [P].US Patent:4473665,1984
[31]牟文杰,吴舜英.微孔泡沫塑料成型研究进展[J].中国塑料,2002,16(65):7
[32]N.S.Ramesh.Heterogeneous nucleation of microcellular foams assisted by the survival of microvoids in polymers containing low glass transition particles Part Ⅰ:mathematical modeling and numerical simulation[J].Polym Eng&Sci,1994,34(22):1685-1697
[33]Doroudiani.Effect of the crystallinity and morphology on the microcellular foam structure of semicrystalline[J].Polym Eng&Sci,1996,36(21):2645-2662
[34]D.F.Baldwin,C.B.Park,N.P.Sun.Super microcellular foamed plastics[P].US Patent,5334 356,1994.
[35]N.S.Ramesh.Numerical and experimental studies of bubble growth during the microcellular foaming process[J].Polym Eng&Sci,1991,31(23):16517
[36]李从威,周南桥,王全新.微孔发泡注射成型设备及技术研究进展[J].工程塑料应用,2008.36(10):76-79
[37]何继敏.新型聚合物发泡材料及技术[M].北京:化学工业出版社,2008,335-360
[38]杨卫民,丁玉梅,谢鹏程.注射成型新技术[M].北京:化学工业出版社,2008,298-300
[39]凯尔文T.奥卡莫特著,张玉霞泽.微孔塑料成形技术[M].北京:化学工业出版社,2004,187-190
[40]张纯,罗筑,何力.二次开模注射成型微孔发泡PP工艺及其性能研究[J].中国塑料,2005.19(8):67-68
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