Optical laminate and method for producing optical laminate

Abstract

Disclosed is an optical laminate which is prevented from occurrence of curling (warping), while maintaining adequate pencil hardness and having excellent durability. The optical laminate is capable of preventing decrease in durability of an image display screen due to the outside light when used as a protection film for the image display screen. Specifically disclosed is an optical laminate in which at least a hard coat layer is formed on a light-transmitting substrate. The optical laminate is characterized in that: the hard coat layer is obtained by curing a composition for the hard coat layer containing a polyfunctional ultraviolet-curable (meth)acrylate resin, an ultraviolet absorbent and a photopolymerization initiator by irradiation of ultraviolet light; the hard coat layer has a Martens hardness (A) of 230-320 N / mm2 in a surface that is on the reverse side of the light-transmitting substrate-side surface; the light-transmitting substrate-side surface of the hard coat layer has a Martens hardness (B) of 160-250 N / mm2; the Martens hardness (A) is larger than the Martens hardness (B); and the elastic modulus of the hard coat layer is continuously changed in the thickness direction.

Description

technical field [0001] The present invention relates to an optical layered body and a method for producing the optical layered body. Background technique [0002] As a protective film for image display screens such as display screens, monitors, and touch screens, it is known that there are hard coat properties (scratch resistance), antistatic properties (prevention of dust adhesion, and prevention of liquid crystal orientation disorder caused by static electricity). Optical laminates with functions such as reflectivity (improving visibility), anti-glare, anti-fouling, and (fingerprint prevention). [0003] In such an optical layered body, especially when used in a liquid crystal display, a triacetyl cellulose film (hereinafter referred to as a TAC film) is used as a base material from the viewpoint of excellent birefringence and transparency. However, when a TAC film is used as a base material, it is difficult to form a film by a melting method, and the base material has to...

AI Technical Summary

Problems solved by technology

However, this UV curable resin tends to shrink due to UV irradiation

Therefore, the following problems arise: the thinner the base material, the more prominent the curl of the optical layered body, especially in the case of roll processing, wrinkles tend to occur in the TD direction (transverse direction), making it difficult to perform desired processing.

However, this kind of hard coating film has the following problems: the hard coating layer is composed of multiple layers, so it needs to be coated several times in the forming process, and the processing rationality is poor.

[0012] However, general ultraviolet curing is carried out by irradiating light with high ultraviolet intensity near the wavelength of 360 nm. Therefore, in the inventions described in Patent Documents 5 to 8, the entire coating film can be fully cured, but on the other hand, The hardness of the coating film near the base material becomes high, and problems such as wrinkles and spots are not sufficiently resolved

[0013] Further, in the invention described in Patent Document 7, the cost of equipment for curing the coating film is high, and the production cost becomes high. In addition, when a thin TAC film is used as a base material, there is also a problem with the TAC film. The problem of deterioration of strength

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