Adhesive sheet

Abstract

Disclosed is an adhesive sheet comprising a substrate and an adhesive layer formed from an adhesive composition containing a polyrotaxane (A) for which a linear molecule penetrates the aperture parts of at least two cyclic molecules, one or more reactive groups exist in the aforementioned cyclic molecules, and a blocking group exists at both terminals of the aforementioned linear molecule. The rupture elongation of the aforementioned adhesive layer is 300% or higher, the haze value is 30% or less, and the retention strength of the aforementioned adhesive sheet measured in accordance with JIS Z0237-except that the measurement temperature is 80 DEG C-is 1000 micrometers or less as the displacement of the aforementioned adhesive sheet after 70,000 seconds. When applied to an optical member such as a polarizing plate or a retardation plate, due to said adhesive sheet and the adhesive layer thereof the stress-relaxation property and thus the ability to prevent optical leakage are excellent, and the durability is excellent, while optical characteristics such as the total light transmittance are sufficiently achieved.

Description

technical field [0001] The present invention relates to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer suitable for optical use and excellent in stress relaxation properties and durability. Background technique [0002] In general, in a liquid crystal panel, a polarizing plate or a retardation plate is bonded to a glass substrate or the like using an adhesive layer formed from an adhesive composition in many cases. However, since optical components such as polarizers and retardation plates tend to shrink when exposed to heat, it has been pointed out that there is a problem that shrinkage occurs due to heat exposure, and as a result, the adhesive layer laminated on the optical component cannot follow the shrinkage. Separation occurs at the interface (so-called swelling, peeling) or light leakage (so-called leakage) occurs due to deviation of the optical axis of the optical member due to stress when the optical member shrinks. [0003] As a met...

AI Technical Summary

Problems solved by technology

However, since optical components such as polarizers and retardation plates tend to shrink when exposed to heat, it has been pointed out that there is a problem that shrinkage occurs due to heat exposure, and as a result, the adhesive layer laminated on the optical component cannot follow the shrinkage. Leakage at the interface (so-called swelling, peeling) or light leakage (so-called leakage) caused by the deviation of the optical axis of the optical part due to stress when the optical part shrinks

[0005] However, in an adhesive layer formed from an adhesive composition to which a plasticizer or liquid paraffin is added, the plasticizer or liquid paraffin seeps out with time, causing various problems such as contamination of the liquid crystal cell.

In addition, in the adhesive composition to which the polyurethane elastomer is added, the addition amount of the polyurethane elastomer is limited from the viewpoint of the compatibility with other components, therefore, the improvement of the stress relaxation property is insufficient, and further, problems caused by Problems such as white turbidity caused by the compatibility of acrylic adhesives and polyurethane elastomers

Thus, in the prior art, it is difficult to fundamentally improve the light leakage prevention and durability of the adhesive layer formed from the adhesive composition for optical parts.

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