JPS61172117A - Optically adhering method of transparent substrate - Google Patents

Abstract

PURPOSE:To obtain a uniform optically adhesive layer which obviates the sticking of dust and impurities and to make possible the simultaneous adhesion of multiple sheets of substrates by using a thermoplastic film consisting of embossed polyvinyl butyral, ethylene/vinyl acetate copolymer, etc. as the adhesive layer. CONSTITUTION:The embossed thermoplastic film is used as the adhesive layer in optical adhesion of at least two sheets of substrates including a flexible substrate. Embossing is effective in removing effectively the air existing between the substrates and the adhesive film in the stage of pasting the substrates and permits optical adhesion. A method for press welding under heating by heat rollers, a heating method in a vacuum pack, etc. are possible as the method of the pasting and the pasting at 60-100 deg.C is possible. The embossed thermoplastic film has no tack on the surface and does not capture dust. The dust picked up on the surface is easily removable by blowing with air, etc. or cleaning with water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application to which the Invention Pertains] The present invention relates to a method for optically adhering substrates, at least one of which is 7-lexiple. More specifically, the present invention relates to a method for optically adhering a functional film to the front surface of a display such as a liquid crystal display.

[Conventional technology]

Conventionally, as methods for optically bonding two or more substrates, at least one of which has a 7-lexiple structure, the following methods have been used: (1) a method using a liquid adhesive, (2) a method using an adhesive, and the like. When using a liquid adhesive, a solvent processing facility is required, and even solvent-free adhesives are difficult to handle. On the other hand, when an adhesive is used, dust and impurities tend to adhere to the surface due to the tackiness of the optical surface, making it difficult to obtain a clean adhesive surface. The above problem was particularly noticeable in the display field where precision adhesion is required. Furthermore, in the above method, when a large number of substrates are bonded together, the work must be performed sequentially, resulting in a long process.

[Problem that the invention seeks to solve]

The present invention aims to solve the above-mentioned problems, to realize easy, clean and uniform optical adhesion, and to simultaneously bond a large number of sheets. [Means for solving the problems] This invention In order to solve the above problem, the invention provides one adhesive layer,
It is characterized by the use of an embossed thermoplastic film such as polyvinyl butyral or ethylene-vinyl acetate copolymer.

[Effect]

Embossed thermoplastic film has no tack on the surface, so it does not trap dust on the surface like adhesives do. Furthermore, even if dust should adhere to the surface, it can be easily removed by blowing it out with air or washing it with water.

Therefore, it is easy to obtain a clean adhesive layer. or,
Since it is in the form of a film, it is easy to handle.

Further, embossing is useful for effectively removing air between the substrate and the adhesive film when bonding the substrates, and enables optical bonding. The bonding can be carried out by heating and pressing with a hot roller, heating in a vacuum pack, etc., and the bonding can be carried out at a temperature of 60 to 100°C.

Furthermore, when an embossed thermoplastic film is used, a large number of substrates can be stacked with the film interposed therebetween and bonded together at the same time by the above-mentioned hot roller method, vacuum pack heating method, or the like.

〔Example〕

The following will explain the liquid crystal display element used in this study as an example.

Example 1 An embossed polyvinyl butyral film was used to attach a polarizing plate to a liquid crystal cell of a liquid crystal display element. The liquid crystal cell used was composed of two glass substrates, each measuring approximately 8 cm x 20 cm. The polarizing plate used was one in which both sides of a dyed PvA film were sandwiched between TAO films. The thickness of the embossed polyvinyl butyral film was approximately (13 m).The liquid crystal cell, polyvinyl butyral, and polarizing plate were stacked in this order into a rubber bag, and then the air inside the bag was While drawing the pressure down to about 1 torr using a vacuum pump, the sample was placed in a constant temperature bath at about 80° C. and maintained for about 50 minutes.

The test piece taken out had no dust or air bubbles in the adhesive layer, and good optical adhesion was achieved, with absorption and reflection in the adhesive layer being practically negligible. In addition, after leaving the test piece at room temperature for about 1 day, it was placed at 60°C and 90% RH for 50°C.
Although it was left for ttH, there was no peeling of the adhesive layer or generation of bubbles, and the initial optical state was maintained.

Example 2 PKT films subjected to anti-reflection treatment on the surfaces of the liquid crystal cell of the liquid crystal display element and the polarizing plate 1 were stacked with embossed polyvinyl butyral films interposed therebetween, and bonded in the same manner as in Example 1 to obtain uniform optical adhesion. . Furthermore, even after the test piece was left at 60°C and 90% RH for 500 hours,
The performance of the adhesive layer remained unchanged.

Example 5 A PI film with anti-reflection treatment on the surface was placed on the glass plate in front of the display of a guest-host type liquid crystal display element.
It was laminated using an embossed ethylene-vinyl acetate copolymer film.

LCD display element, embossed film, i'1li
The T films were stacked one on top of the other in order and bonded by passing them through a heated roller at 90° C. and applying a pressure of about 500 f/an at a speed of about 5 mn/air. Similar to the other examples, uniform optical adhesion was obtained.

Although the above embodiments took liquid crystal display elements as an example, the same method as the above embodiments can be applied to other display fields that require precise adhesion, especially in the flat display field.

〔Effect of the invention〕

As described above, according to the present invention, a uniform optical adhesive layer free of dust and impurities can be obtained. Furthermore, a large number of substrates can be bonded simultaneously.

Furthermore, as shown in the examples, the bonded adhesive layer has sufficient durability and therefore has a wide range of applications.

As described above, the present invention is a method that is far more useful than conventional methods, and is particularly useful in all fields other than the display elements used in the examples, where precise optical adhesion is desired to be obtained without dust or impurities. It is.

Claims (1)

[Claims] 1. A method for optically adhering transparent substrates, the method comprising using an embossed thermoplastic film as an adhesive layer in optically adhering at least two substrates including a flexible substrate.