申请人:RÖHM GMBH
公开号:EP0451310A1
公开(公告)日:1991-10-16
Modified rubber compositions comprise by weight about 15-60% of a highly saturated aliphatic rubber such as ethylene-propylene-diene rubber, about 25-80% of acrylate monomer units; and less than about out 5% multi-functional monomer units. The compositions exist as amorphous heterogeneously dispersed phases. The first phase comprises the copolymer rubber to which polymers of at least 10%, preferably 20%, and more preferably 30% of the other monomer units are grafted. The second phase comprises the other monomers polymerized as homo and copolymers, not grafted to the rubber. Optionally, up to 20% of the composition comprises high index monomer units, e.g., those providing phenyl groups (preferably styrene) having an index of refraction greater than that off the rubber, preferably greater than that of polyacrylate. The high index monomer units may be copolymerized with the acrylate and grafted to the rubber. Greater than 10% and preferably 20% of the monomer units other than rubber are grafted to the rubber. The number average molecular weight of the grafts is between 10,000 and 80,000 daltons. bout 2-20% by weight of one or more polymers may be provided to adjust the refractive indices of the rubber or the polyacrylate phase in the final product such that when the composition is present at the 10% rubber level, the haze can be reduced to less than 20%., Examples for modifying the refractive index of the rubber phase, other than those grafted to the rubber, are block copolymers comprising at least one block providing high index monomer units (preferably styrene) having a higher refractive index than rubber, preferably higher than polyacrylate and at least one block of a saturated aliphatic polymer compatible with the rubber, such as hydrogenated polyisoprene., Other polymers compatible with the polyacrylate phase and having a lower index of refraction than that of polyacrylate, preferably less than the rubber such as those providing vinylidene fluoride monomer units may be utilized. The compositions may be stored and transported to the place of manufacture of polyacrylate products and there incorporated into polyacrylate products to form up to about 80% by weight of said products having high strength and if desired, high clarity.
改性橡胶组合物按重量计包括约 15-60%的高饱和脂肪族橡胶(如乙烯-丙烯-二烯橡胶)、约 25-80%的丙烯酸酯单体单元和小于约 5%的多功能单体单元。组合物以无定形异质分散相的形式存在。第一相由共聚橡胶组成,共聚橡胶上接枝了至少 10% 的聚合物,最好是 20%,更多的是 30% 的其他单体单元。第二相包括未接枝到橡胶上的其他单体聚合为均聚物和共聚物。可选地,组合物中最多 20% 的单体单元为高折射率单体单元,例如,提供苯基(最好是苯乙烯)的单体单元,其折射率大于橡胶的折射率,最好大于聚丙烯酸酯的折射率。高折射率单体单元可与丙烯酸酯共聚并接枝到橡胶上。橡胶以外的单体单元接枝到橡胶上的比例大于 10%,最好是 20%。接枝物的平均分子量介于 10,000 和 80,000 道尔顿之间。 可提供约 2-20% (按重量计)的一种或多种聚合物,以调整最终产品中橡胶或聚丙烯酸酯相的折射率,从而当组合物中橡胶含量为 10% 时,雾度可降至 20% 以下。除了接枝到橡胶上的聚合物外,还可以使用嵌段共聚物来改变橡胶相的折射率,嵌段共聚物包括至少一个提供高折射率单体单元(最好是苯乙烯)的嵌段,其折射率高于橡胶,最好高于聚丙烯酸酯,以及至少一个与橡胶相容的饱和脂肪族聚合物嵌段,如氢化聚异戊二烯、也可使用与聚丙烯酸酯相容且折射率低于聚丙烯酸酯(最好低于橡胶)的其他聚合物,如提供偏氟乙烯单体单元的聚合物。这些组合物可以储存和运输到聚丙烯酸酯产品的制造地,并在那里掺入聚丙烯酸酯产品中,形成重量比高达约 80% 的具有高强度和高透明度(如果需要)的上述产品。