摘要
为了改善聚乙烯醇(PVA)水溶液在室温下易产生凝胶的缺点,以利于涂覆法高阻隔性能 PP/PVA/PE 或 PVA/PE 复合薄膜的生产操作。本文以聚乙烯醇缩甲醛(PVF)水溶液代替 PVA 水溶液,研究了 PP/PVF/PE 复合薄膜透氧性及其与 PVF结构的关系。以气相色谱法测定的 PP/PVF/PE 复合薄膜透氧率的结果表明:随 PVF 缩醛度的增加,其复合膜透氧率上升很小,(在缩醛度<40%情况下),仍属高阻隔性能的复合膜材料。红外光谱分析表明:其 PVA 水溶液的缩甲醛化几乎仅发生在 PVA 的全同立构单元上、产生顺式缩甲醛结构。而其顺式缩甲醛结构对 PVF 的结晶性影响较小.这些正是 PP/PVF/PE 复合膜仍保持优良的氧气阻隔性能的原因所在。粘度测定实验表明:缩醛度为17%左右时,其 PVF 水溶液粘度值最低,并具有良好的室温贮存稳定性。
In the coating process of PP/PVA/PE laminated film,polyvinyl alcohol(PVA)aqueous solution was replaced by polyvinyl formals aqueous solutionto aviod the problem that the PVA solution(conc.>10%)tended to gel atroom temperature.However,the influence of acetalization of PVA on itsoxygen permeability was seldom reported.In this work,the relations betweenoxygen permeability and structure of polyvinyl formals(PVF)with differentdegree of formalization were investigated by means of Gas Chromatography andFT-IR respectively.It was discovered that PP/PVA/PE film had very low oxygen permeabi-lity,and upon being acetalized,the permeability of PP/PVF/PE films tooxygen increased slightly with rising degree of formalization(see Table 1).Infrared spectra showed that at 800cm^(-1)(actually at 797cm^(-1)),the absorptionbands of cis-form formal from iso-form PVA became gradully obvious asincrease of degree of formalization(Fig.1),but the absorption band oftrans-form formal from syndio-form PVA at 785cm^(-1) was hardly observed.The-refore,the high crystalline syndio-form PVA still remained after formaliza-tion,which kept the PP/PVF/PE laminated films with high oxygen barrier.At about 17% degree of formalization,the visicosity of PVF aqueoussolution reached minimum.Meanwhile,the PP/PVF/PE film maintainodlower oxygen permeability(about 2.5ml/m^2·24hr·atm)than those of PP/PVDC/PE film(47.3ml/m^2·24hr·atm)and PP/PA/PE film(79.6ml/m^2·24hr·arm)under the same testing condition.
出处
《中国塑料》
CAS
CSCD
1991年第2期31-37,共7页
China Plastics
基金
南京市科委资助项目
