Retardation film, polarizing plate, and display panel device

Abstract

A retardation film which comprises a stretched polymer film and satisfies the following formulae (1) to (3): 0.70<Re[450] / Re[550]<0.97(1); 1.5×10-3<Deltan<6×10-3(2); and 1.13<NZ<1.50(3), wherein: Re[450] and Re[550] represent in-plane retardation values of the retardation film as measured at 23° C. using light with a wavelength of 450 nm and light with a wavelength of 550 nm, respectively; Deltan represents an in-plane birefringence equal to (nx-ny) (where nx and ny represent refractive indexes in a slow axis direction and a fast axis direction of the retardation film, respectively); and NZ represents a ratio of a thickness-direction birefringence equal to (nx-nz) (where nz represents a refractive index in a thickness direction of the retardation film) to the in-plane birefringence equal to (nx-ny).

Description

technical field [0001] The present invention relates to a retardation film comprising a stretched polymer film. Background technique [0002] In recent years, along with the spread of displays, various functions required for optical films used therein are also increasing. Therefore, it is required to develop membranes manufactured with new materials and new processes. [0003] In addition to the performance of the film, it is necessary to mass-produce a wide and thin film in order to cope with the increase in the size and thickness of displays and the increase in production volume. When producing such a thin-layer film, the strength of the film becomes an important design parameter in terms of runnability, processability, and product reliability. [0004] In terms of running properties, since a long film is continuously produced for mass production, the film is generally conveyed by rollers while being brought into contact with various rollers. In this case, there is a pr...

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Problems solved by technology

[0005] In terms of film processability, if the film strength is weak, there are problems of force when cutting the film into sheets, bending when bonding the films to each other or bonding the film to the panel, and reworking the film from the panel Under the action of bending, etc., there will be problems such as cracking on the film.

As one of the retardation films, for example, as shown in Patent Documents 1 and 2, a retardation film having a characteristic (also referred to as an inverse wavelength dispersion characteristic) in which the retardation value is larger as measured with longer-wavelength light has been developed, but The improvement of the brittleness of the membranes as described above is not addressed in these documents

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