Birefringent film, method for producing same, and method for producing optical film

• Main Author: SHIBATA YUJI
• Format: Patent
• Language: Chinese; English
• Published: 01.09.2023
• Subjects: PERFORMING OPERATIONS; PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

The present invention relates to a birefringent film containing a solvent A, a solvent B, and a polymer having crystallinity, in which the boiling point Bp (SA) (DEG C) of the solvent A and the boiling point Bp (SB) (DEG C) of the solvent B satisfy Bp (SA)-Bp (SB) > = 5, the total content of the solvent A and the solvent B in the birefringent film is 0.01-3 wt%, and Rth < =-100 nm is satisfied. The present invention pertains to a production method including a step in which a specific film is brought into contact with a mixed solvent containing a solvent A and a solvent B, and the birefringence of the film in the thickness direction is changed. 本发明涉及一种双折射膜，其包含溶剂A、溶剂B、和具有结晶性的聚合物，上述溶剂A的沸点Bp(SA)(℃)与上述溶剂B的沸点Bp(SB)(℃)满足Bp(SA)－Bp(SB)≥5，上述双折射膜中的上述溶剂A和上述溶剂B的合计含量为0.01重量％以上且3重量％以下，满足Rth≤－100nm。本发明涉及一种制造方法，包括使特定的膜与包含溶剂A和溶剂B的混合溶剂接触，使膜沿厚度方向的双折射变化的工序。