申请人:SEKISUI CHEMICAL CO., LTD.
公开号:EP1821122A1
公开(公告)日:2007-08-22
It is the object of the present invention to provide a retardation film comprising a norbornene type copolymer, being excellent in heat resistance, low specific gravity, low birefringence, low photoelasticity, and low chromatic dispersion and having high performance of retardation compensation.
The present invention is a retardation film, which comprises a norbornene type copolymer composition containing a norbornene type copolymer containing 40 to 60% by mole of a repeating unit derived from at least one kind of a norbornene type monomer selected from a group consisting of a monomer represented by the general formula (I), a monomer represented by the general formula (II), a monomer represented by the general formula (III), a monomer represented by the general formula (IV) and a monomer represented by the general formula (V), and 60 to 40% by mole of a repeating unit derived from an acyclic olefin type monomer, a stretched film obtained by forming the norbornene type copolymer composition in a film form and then stretching the film two times as large while heating the film to a glass transition temperature determined by a dynamic viscoelasticity, having an in-plane birefringence value Δn defined by the following formula in a range of 0.0033 or higher:
本发明的目的是提供一种包含降冰片烯类共聚物的缓凝薄膜,该薄膜具有优异的耐热性、低比重、低双折射、低光弹性和低色散,并且具有较高的缓凝补偿性能。
通式(IV)代表的单体、通式(III)代表的单体、通式(V)代表的单体,以及 60% 至 40% (以摩尔计)由无环烯烃型单体衍生的重复单元组成的单体,将降冰片烯型共聚物组合物形成薄膜状,然后将薄膜拉伸两倍,同时将薄膜加热至由动态粘弹性确定的玻璃化转变温度,得到的拉伸薄膜具有下式定义的平面内双折射值Δn,其范围为 0.0033 或更高: