Adhesive composition

Inactive Publication Date: 2013-05-09
NITTO DENKO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0037]Adhesive strength of the adhesive composition according to the present invention decreases to the local minimum value after taking the local maximum value, and then, increases to a value greater than the local maximum value along with increase in irradiation amount of electromagnetic wave or particle beam irradiated at intensity lower than critical irradiation intensity. According to the present invention, the adherends may be laminated without any position misalignment by increasing the adhesive strength of the adhesive composition to at least the local maximum value by irradiating the electromagnetic wave or particle beam with an appropriate intensity for a predetermined time under a first predetermined temperature environment. When a correction of the lamination is not required, the two adherends may be bonded at a final strong adhesion by increasing the adhesive strength to a value greater than the local maximum value by further irradiating the electromagnetic wave or particle beam with an appropriate intensity under the first predetermined temperature environment for the predetermined time. The state of the adhesive composition then is cured at the same degree when the adhesive strength is at the local minimum value or is further cured, and if it is attempted to peel the two adherends, cohesion failure may occur in the layer of the adhesive composition and/or within the adherends.
[0038]The adhesive composition according to the present invention allows for increasing the adhesive strength to a value greater than the local maximum value by maintaining the adhesive composition under a second predetermined temperature environment higher than the first predetermined temperature environment for a time equal to or longer than the predetermined time, after the adhesive strength decreased to the local minimum value after taking the local maximum value, by irradiating the electromagnetic wave or particle beam under the first predetermined temperature environment. In this case, the adherends may be laminated without position misalignment by increasing the adhesive strength to at least the local maximum value. When a correction of the lamination is not required, the two adheren

Problems solved by technology

Thus, it is difficult to control change of the size of the polarizing film in an environment where a size of a polarizing film changes by heating or moisturizing after laminating the polarizing film and a liquid-crystal cell via a PSA layer.
If the size of the polarizing film changes, it could cause unevenness in brightness within a surface of a liquid-crystal panel.
In addition, it could cause degradation of view angle characteristics in that a contrast is degraded when the liquid-crystal panel is viewed at an oblique angle.
These demerits may be further noticeable along with upsizing of liquid-crystal panels in coming days.
However, when a thin polarizing film is laminated with a liquid-crystal cell using a PSA, a change in size of the thin polarizing film due to heating, moisturizing or an abrupt temperature change may cause cracks therein.
Because of this, in a present liquid-crystal panel manufacturing technique using a PSA, a thin polarizing film having a protection film laminated only on one of the surfaces of a polarizer has not been put into practical use
Thus, when a force is applied to a surface of a polarizing film, the polariz

Method used

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  • Adhesive composition
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Examples

Experimental program
Comparison scheme
Effect test

Example

[0089]In the same Example 1, for example, when light having energy of 35 to 150 mJ / cm2 was irradiated from the polarizing film side, the state of the layer 2 became “easy-to-peel” state, and the local minimum value of the adhesive strength then was 0.5 N / 25 mm, and the proportion of the reacted monomer when the adhesive strength was at the local minimum value was about 87%.

(Strong Adhesion State)

[0090]After the adhesive strength F started increasing again after taking the local minimum value, if the electromagnetic wave or particle beam with an appropriate intensity is continued to be irradiated to the layer 2 under the first predetermined temperature environment, the adhesive strength F increases along with the increase of the irradiation amount of the electromagnetic wave or particle beam and finally reaches to a value at least greater than the local maximum value. At this point, the polymerization of the adhesive base agent in the layer 2 is almost completed and the layer 2 is at...

Example

Example 2

Measurement of Critical Irradiation Intensity

[0135]A half part of a photo-polymerization initiator (Irgacure819 from Ciba Japan K.K.) was added to 100 parts of N-(2-hydroxyethyl)acrylamide monomer (from Kohjin Co., Ltd.) and dissolved to prepare adhesive composition. To accelerate rate of dissolution, ultrasonic wave was applied while heating at 50° C. One milliliter of the adhesive composition was dropped onto a plate glass with a dropping pipette, a polarizing film (VEGQ5724DU from Nitto Denko Corporation) cut in sheets having a width of 25 mm was laminated therewith. The thickness of the adhesive composition was adjusted to 10 μm. The plate glass laminated with the polarizing film was placed in an oven heated to 40° C., and light was irradiated from the polarizing film side with an ultraviolet irradiator (UBX0801-01 from Eye Graphics Co., Ltd., a high voltage mercury lamp with output of 8 kW). For preventing the temperature of the polarizing film or the plate glass overh...

Example

Example 3

Control of Adhesive Strength and State by Irradiation Intensity of Electromagnetic Wave or Particle Beam

[0138]For the same adhesive strength composition in Example 1, change of state of the adhesive composition depending on the irradiation time when varying the irradiation intensity was observed under the same conditions as Example 1 except the irradiation intensity of light. The irradiation intensity at the wavelength of 405 nm was varied in a range from 1.5 to 35 mW / cm2. The result is shown in FIG. 5, where a cross (x) shows that the adhesive composition was at fluid state, a triangle (Δ) shows that the adhesive composition was at PSA-like state, a circle (◯) shows that the adhesive composition was at easy-to-peel state, and a double circle (⊚) shows that the adhesive composition was at strong adhesion state. From FIG. 5, it is understood that time for the state of the adhesive composition changing to the PSA-like state, time to the easy-to-peel state and time to the stro...

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Abstract

An adhesive composition which allows for preventing misalignment when mutually laminating adherends, mutually strongly bonding the adherends when correction of lamination is not required, as well as peeling the adherends without causing any damage thereto when correction of lamination is required. The adhesive composition includes an adhesive base agent consisting of a monomer and a polymerization initiator. Adhesive strength of the adhesive composition changes to take a local maximum value, a local minimum value and a value greater than the local maximum value along with increase of irradiation amount of the electromagnetic wave or particle beam irradiated to the adhesive composition under a predetermined temperature environment.

Description

TECHNICAL FIELD[0001]The present invention relates to adhesive composition. In particular, the present invention relates to adhesive composition, for example used for mutually laminating two adherends, a substrate and a polarizing film, for manufacturing a liquid-crystal display unit, which develops adhesive strength by irradiation of electromagnetic wave or particle beam and allows for preventing misalignment when laminating and for peeling easily where necessary.[0002]A liquid-crystal display unit used for a liquid-crystal television is, in general, what a driving circuit, a printed circuit board for driving and, where necessary, a back-light are mounted on a liquid-crystal panel. The liquid-crystal panel is configured by laminating sheet-like polarizing films to both surfaces of a rectangular liquid-crystal cell which the configuration elements thereof are a liquid-crystal layer, two glass substrates sandwiching the liquid-crystal layer, transparent electrodes and / or a color filt...

Claims

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Application Information

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IPC IPC(8): C09J139/04G02F1/1335C09J133/20C09J137/00C09J133/26C09J133/02
CPCC09J4/00C09J133/02C09J133/20C09J5/00C09J137/00C09J139/04G02F1/133528C09J133/26C09J7/22C09J7/38C09J2203/318C09J2301/302G02B1/14G02B5/3025G02B5/305G02F1/1335G02F1/133509B32B38/0008B32B38/10C09J133/14C09J133/24
Inventor OKAMOTO, MIKIMORI, TAKUYATAKEDA, KENTAROUNAGATSUKA, TATSUKI
Owner NITTO DENKO CORP
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