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Transparent double-sided self-adhesive sheet

a self-adhesive sheet, transparent technology, applied in the direction of film/foil adhesives, instruments, other domestic objects, etc., can solve the problems of poor long-term reliability, in addition to workability and step-conforming ability, and the inability to use self-adhesive sheets for applications that require optical transmissibility, etc., to achieve excellent workability and excellent conformability.

Inactive Publication Date: 2012-06-21
MITSUBISHI CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0021]Thus, an object of the present invention is to provide a novel transparent double-sided self-adhesive sheet, which, when bonding to an adherend, not only excels in the ability to conform to steps or surface irregularities caused by a printing site, but also excels in the ability to conform to the state of the adherend surface, and furthermore, also excels in workability such as cutting processability.Means to Solve the Problems
[0023]Building-in the indentation hardness (Asker C2) and the amount of creep by shearing to fall in a given range allows the transparent double-sided self-adhesive sheet proposed by the present invention to be provided simultaneously with processability, the ability to follow surface irregularities, and furthermore, the ability to conform to the state of an adherend surface.
[0027]Thus, since the transparent double-sided self-adhesive sheets of the present invention can all be made not only to be transparent and have front and reverse sides that are self-adhesive surfaces, but also to have excellent ability to conform to steps caused by a printing site or the like or to the state of an adherend surface, and, moreover, to have excellent workability such as cutting processability, they can be used suitably for bonding a transparent panel such as a protective panel or a touch panel to an image display panel in flat image display devices that use such image display panels as LCDs, PDPs or ELs, such as, for instance, personal computers, mobile terminals (PDAs), gaming machines, televisions (TVs), car navigation systems, touch panels and pen tablets.

Problems solved by technology

Compared to a joining method whereby an adhesive in liquid form is coated or filled and dried, joining with a self-adhesive sheet has the merit of being simple; however, when adhesion is onto a structure having shapes such as surface asperities, sometimes aspects such as long-term reliability, in addition to workability and step-conforming ability, are poor.
Conversely, if the self-adhesive sheet is hard, while there is no problem in the cutting process or the like, there is no close contact with the steps and surface irregularities due to a lack of softness, and, in addition, adhesive strength becomes difficult to obtain.
However, since a self-adhesive sheet using expanded foam lacks transparency, such self-adhesive sheet cannot be used for an application that requires optical transmissibility.
In addition, a self-adhesive sheet is described in Patent Document 2, in which tensile elongation pertaining to conferring followability is defined; however there is a possibility of poor reliability in regard to foaming and peeling over time due to long-term retention.

Method used

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  • Transparent double-sided self-adhesive sheet
  • Transparent double-sided self-adhesive sheet

Examples

Experimental program
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Effect test

example 1

[0117]With respect to 1 kg of acrylic acid ester copolymer A (Mw=500,000, Mn=62,000, Mw / Mn=8, theoretical Tg: −50° C.) comprising 75 parts by mass of 2-ethylhexyl acrylate (homopolymer Tg: −70° C.), 20 parts by mass of vinyl acetate (homopolymer Tg: 32° C.) and 5 parts by mass of acrylic acid (homopolymer Tg: 106° C.), which had been randomly copolymerized, 150 g of the ultraviolet curable resin propoxylated pentaerythritol triacrylate (ATM-4PL, manufactured by Shin-Nakamura Chemical Co., Ltd.) as a crosslinker and 7 g of 4-methylbenzophenone as a photopolymerization initiator were mixed to prepare an intermediate resin layer composition.

[0118]The intermediate resin layer composition was coated with an applicator onto a release-treated polyethylene terephthalate film (“NP50A”, manufactured by PANAC Corporation; thickness: 50 μm) so as to have a thickness of 130 μm and then the surface was covered with a release-treated polyethylene terephthalate film (E7006, manufactured by Toyobo C...

example 2

[0123]A transparent double-sided self-adhesive sheet (thickness: 160 μm; B-1 / A-2 / B-1=35 / 90 / 35) was prepared in a similar manner to Example 1, except that an intermediate resin layer (A-2) was used, a 90 μm sheet from a block copolymer (“LA2250”, manufactured by Kuraray Co., Ltd.) comprising butyl acrylate (Tg: −56° C.) and methyl methacrylate (Tg: 105° C.), which was melted and shaped in the form of a sheet.

example 3

[0124]The intermediate resin layer composition and the pressure-sensitive adhesive layer composition used in Example 1 were melt-co-extruded so as to have pressure-sensitive adhesive layer composition / intermediate resin layer composition / pressure-sensitive adhesive layer composition, and at the same time as this was superposed onto the release-treated side of a release-treated polyethylene terephthalate film (“MRF75”, manufactured by Mitsubishi Plastics, Inc.) to be shaped in the form of a 250 μm-thick sheet, it was covered by superposing the release-treated side of a polyethylene terephthalate film to which a release-treatment had been applied (“E7006”, manufactured by Toyobo Co., Ltd.). Next, 1300 mJ of ultraviolet light was irradiated from both the front and back sides with a high-pressure mercury lamp through these polyethylene terephthalate films to crosslink the intermediate resin layer composition and the pressure-sensitive adhesive layer composition and produce a self-adhesi...

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Abstract

A transparent double-sided self-adhesive sheet is provided which, when bonding to an adhered, not only excels in the ability to conform to steps or surface irregularities caused by a printing site, but also excels in workability such as cutting processability. A transparent double-sided self-adhesive sheet is proposed, having an intermediate resin layer (A) and pressure-sensitive adhesive layers (B) as front and reverse side layers, each of the layers being a layer having one or more species of (meth)acrylic acid ester series (co)polymer as the base resin, in which transparent double-sided self-adhesive sheet, the shear storage elastic modulus (G′(A)) at a frequency of 1 Hz of the intermediate resin layer (A) is higher than the pressure-sensitive adhesive layers (B) in a temperature range of 0° C. to 100° C., and, the indentation hardness (ASKER C2 hardness) of the entire sheet is 10 to 80.

Description

TECHNICAL FIELD[0001]The present invention relates to a transparent double-sided self-adhesive sheet that can be used suitably for bonding structural members of an image display device such as an image display panel, a protective panel and a touch panel in flat image display devices that use such image display panels as LCDs, PDPs or ELs, such as, for instance, personal computers, mobile terminals (PDAs), gaming machines, televisions (TVs), car navigation systems, touch panels and pen tablets.BACKGROUND ART[0002]Currently, self-adhesive sheets are being used broadly in every field in order to produce a single body by adhering structural members thereof. Compared to a joining method whereby an adhesive in liquid form is coated or filled and dried, joining with a self-adhesive sheet has the merit of being simple; however, when adhesion is onto a structure having shapes such as surface asperities, sometimes aspects such as long-term reliability, in addition to workability and step-conf...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B7/10C09J7/00C08F220/10B32B7/02C09J7/24
CPCC09J7/0267C09J2201/128C09J2203/318C09J2433/006C09J133/10Y10T428/24959B32B27/30B32B27/308B32B2457/202G02F2202/28Y10T428/2891B32B7/12B32B2457/00C09J7/24C09J2301/124C09J7/385C09J7/22C09J7/38C09J133/04C09J2301/40C09J2301/312
Inventor NIIMI, KAHORUYOSHIKAWA, HIDEJIROUYAMAOKA, TETSUYAINENAGA, MAKOTO
Owner MITSUBISHI CHEM CORP
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