JPH0959577A - Production of sheet with pressure-sensitive adhesive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tack agent layer-bearing sheet mainly for optical use in an industrially advantageous way by taking a special film formation process using a pair of rolls to deal with, all at once, such pending problems in conventional coating processes as dust adherence, workplace environment aggravation, disadvantages in terms of utility, equipment cost and equipment-occupying space, limitations in line speed, curling, film defect development and damage of the partner sheet. SOLUTION: A pair of rolls arranged in parallel with each other in a slightly spaced way is fed with a substrate sheet 1 and a releasable sheet 2, and (a) a fluid or nonsolvent-type high-viscosity tacky resin composition for forming (A) a tack agent layer is delivered toward the gap between the rolls and both the rolls are revolved in such directions as to bite mutually to ensure the composition (a) to be held in between both the sheets 1 and 2 to serve the composition (a) as the tack agent layer A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical sheet having a pressure-sensitive adhesive layer.

[0002]

2. Description of the Related Art A liquid crystal display device basically has a structure in which polarizing plates are arranged on both sides of a liquid crystal cell, and a phase plate is interposed between the polarizing plate on the incident light side and the liquid crystal cell. There are also many. That is, the liquid crystal display element has a structure of polarizing plate / liquid crystal cell / polarizing plate or polarizing plate / phase plate / liquid crystal cell / polarizing plate.

When assembling a liquid crystal display element, a polarizing plate or a phase plate provided with an adhesive layer and a release sheet on one side is prepared in advance (usually purchased from a specialized manufacturer), and the release sheet is prepared. It is carried out by adhering to the other party (liquid crystal cell or liquid crystal cell with a phase plate) while peeling and removing.

Now, in order to provide a pressure-sensitive adhesive layer and a release sheet on one side of a polarizing plate or a phase plate, (i) after coating the solution of the pressure-sensitive adhesive composition on the release sheet side, drying the solvent. A method of adhering it to the polarizing plate or phase plate side, and (ii) coating the solution of the pressure-sensitive adhesive composition on the polarizing plate or phase plate side, then removing the solvent by drying, and then separating. Either of the methods of coating the formability sheet is adopted, but industrially, in most cases, the former method (i), which is less likely to damage the polarizing plate or the phase plate, is adopted. .

[0005]

[Problems to be Solved by the Invention]
The methods (i) and (ii) include the following problems because they are a method of performing coating using a solvent solution and then drying. Since coating and drying are performed in an open state and take a long time, dust easily adheres to the coated surface,
Also, the working environment should be deteriorated due to the evaporation of the solvent during coating and drying. Since it requires drying, it is disadvantageous in terms of utility, equipment cost and equipment occupying space, and there is a limit in line speed. During the drying process, curling is likely to occur as the solvent evaporates. The coating film is likely to have film defects such as streaks, scratched skin, unevenness, and entrapment of air bubbles, which may result in a decrease in adhesive strength, a decrease in optical characteristics, and a decrease in aesthetics. Even when the release sheet side is coated with the solution of the pressure-sensitive adhesive composition as in (i) above, the residual sheet after drying may affect the other sheet.

Under the circumstances described above, the present invention is
By adopting a special film-forming method using a pair of rolls, various problems that have been pending in the conventional coating method (dust adhesion, deterioration of working environment, utility disadvantage, equipment cost increase) Disadvantages, disadvantages in equipment occupancy space, line speed restrictions, curling, film defects, damage to the other party sheet) are solved all at once, and an optical sheet mainly having an adhesive layer is industrially advantageous. It is an object of the present invention to provide a method for manufacturing.

[0007]

The method for producing a sheet having an adhesive layer according to the present invention comprises a base sheet (1) and a releasable sheet on a pair of rolls arranged in parallel with a slight gap.
(2) and supply it to the gap between the rolls, and the adhesive layer (A)
The base sheet (1) and the releasable sheet (2) are discharged by ejecting the flowable non-solvent type high-viscosity adhesive resin composition (a) for forming, and rotating both rolls in the direction to bite each other. The high-viscosity adhesive resin composition (a) is sandwiched between and to form the adhesive layer (A).

In this case, the non-solvent type high-viscosity adhesive resin composition (a) contains a component which is cured by heating or irradiation with active energy rays, and the base sheet (1) and the release sheet (2) are included. High viscosity adhesive resin composition between (a)
It is desirable that the adhesive layer (A) is obtained by providing a means for curing the high-viscosity adhesive resin composition (a) in such a state that it is sandwiched.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The substrate sheet (1) is an optical sheet or device such as a polarizing element film, a polarizing plate, a phase plate, a retardation element film, and a liquid crystal display element; the surface of these optical sheet or device is covered. Protective film; Color filter; Film with transparent electrode; Single-layered or multi-layered plastics film (including a film having a cured crosslinkable resin layer, an organic air permeation resistant layer, an inorganic air permeation resistant layer, etc.); An optical sheet such as a film; a scratch resistant film; The invention is not limited to the optical sheet, and can be applied to various other purpose sheets (including paper and metal foil). Since the base sheet (1) has various kinds, the thickness thereof is not particularly limited as long as it has flexibility.

The releasable sheet (2) is a sheet having releasability on at least one side, for example, a polycarbonate film, a polyarylate film, a polyethersulfone film, a polysulfone film, a polyester film, a polystyrene film, a polyolefin film, norbornene. -Based films, phenoxyether type polymer films, single-layer or multi-layered plastics films such as organic air permeation resistant films and sheets that have been subjected to release processing with a silicone-based release agent, fluororesin films, Examples thereof include a film having a mold release property such as a certain type of polyolefin film, and a film formed by internally adding a release agent. The thickness of the release sheet (2) is not limited, but is usually 5 to 500 μm,
It is often often 10 to 100 μm.

The release sheet (2) may or may not be optically isotropic when it is finally peeled off and used, but it can be used for optical purposes without peeling. When performing, it is usually necessary to be optically isotropic.
However, when it is provided on the front surface of the polarizing plate on the incident light side, it need not be optically isotropic.

As the fluid non-solvent type high viscosity adhesive resin composition (a) for forming the adhesive layer (A),
A pressure-sensitive adhesive grade acrylic polymer obtained by copolymerizing a monomer component that gives a soft segment and a monomer component that gives a hard segment (further, a functional group-containing monomer component or a polyfunctional (meth) acrylate component as necessary) Those that are essential components are preferably used.

Here, as a monomer component which gives a soft segment when polymerized, an alkyl acrylate having an alkyl group having 4 or more carbon atoms (n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, etc.), an alkyl group An alkyl methacrylate having 6 or more carbon atoms (n-hexyl methacrylate, 2-
Ethylhexyl methacrylate, etc.) and the like.
Examples of the monomer component that gives a hard segment include alkyl acrylates having an alkyl group having 1 to 3 carbon atoms (methyl acrylate, etc.), alkyl methacrylates having an alkyl group having 1 to 5 carbon atoms (methyl methacrylate, etc.), vinyl acetate, styrene, etc. Can be given. Examples of the functional group-containing monomer component include acrylic acid, methacrylic acid, crotonic acid, (anhydrous) itaconic acid, (anhydrous) maleic acid, fumaric acid, glycidyl (meth) acrylate, and N-methylol acrylamide. As the polyfunctional (meth) acrylate component, ethylene glycol,
Polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butylene glycol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, glycerin and pentaerythritol. Examples thereof include di-, tri- or poly (meth) acrylates.

Since the above-mentioned pressure-sensitive adhesive grade acrylic polymer usually lacks in fluidity even if it is heated by itself, it is a fluid non-solvent type for forming the pressure-sensitive adhesive layer (A). High viscosity adhesive resin composition (a)
In order to achieve the above, it is desirable to add a component that is cured by heating or irradiation with active energy rays. As the curing component, the above-mentioned monomer that gives a soft segment, a monomer that gives a hard segment, a functional group-containing monomer, and a polyfunctional (meth) acrylate are used in a monomer form. These monomers act as a plasticizer of the acrylic polymer at the time of film formation to give fluidity, and are polymerized later by taking a curing means. With such a monomer or in place of such a monomer, a relatively low molecular weight oligomer or a common plasticizer can be used.

As the high-viscosity adhesive resin composition (a), in addition to the above-mentioned acrylic polymer as an essential constituent element, a rubber-based, vinyl-based, silicone-based or other adhesive-grade resin composition is also available. Can be used.

The viscosity of the fluid non-solvent type high-viscosity adhesive resin composition (a) for forming the adhesive layer (A) is
1000 to 100000 cps / 20 ° C, preferably 30
00-80,000 cps / 20 ° C, more preferably 5000
It is suitable to set it to -50000 cps / 20 ° C.

In order to produce a sheet having an adhesive layer according to the present invention, first, a base sheet (1) and a releasable sheet are placed on a pair of rolls arranged in parallel with a slight gap.
(2) and supply it to the gap between the rolls, and the adhesive layer (A)
The fluid non-solvent type high-viscosity adhesive resin composition (a) for forming is discharged. Then, by rotating both rolls in a direction in which they bite each other, the high-viscosity adhesive resin composition (a) is sandwiched between the base material sheet (1) and the release sheet (2) to form an adhesive. Form with layer (A).

In this case, when the non-solvent type high-viscosity adhesive resin composition (a) contains a component which is cured by heating or irradiation with active energy rays, a base sheet
After the high-viscosity adhesive resin composition (a) is sandwiched between (1) and the release sheet (2), the high-viscosity adhesive resin composition ((a) is sandwiched in such a state. It is desirable to form a pressure-sensitive adhesive layer (A) by taking a curing means for a). Examples of the curing means include heating and irradiation with active energy rays (ultraviolet rays, electron rays, and in some cases visible rays). When curing the composition by irradiation with ultraviolet rays or visible light, add 0.5% of the high viscosity adhesive resin composition (a) to the whole in advance.
It is usual to add about 5% by weight of a photopolymerization initiator. In the case of irradiation with active energy rays, curing can be completed by performing heat treatment as necessary after irradiation.

Thus, the substrate sheet (1) / adhesive layer
A target sheet having the layer structure of (A) / release sheet (2) is obtained. When the pressure-sensitive adhesive layer (A) is provided on both sides of the base material sheet (1), the above-mentioned base material sheet (1) / pressure-sensitive adhesive layer (A) / release sheet (2) and release sheet (2) ) And the same operation as above may be repeated. The layer structure at this time is: releasable sheet (2) / adhesive layer (A) / base material sheet (1) / adhesive layer (A) / releasable sheet (2). The release sheet (2) may be removed by peeling at the time when the necessity arises, and may not be removed by peeling depending on the application.

Next, the operation will be described. In the present invention, since the special film forming method using a pair of rolls is adopted, various problems (adhesion of dust, deterioration of working environment, utility, etc.) which have been a problem in the conventional coating method are caused. Disadvantages, equipment cost disadvantages, equipment occupation space disadvantages, line speed restrictions, curling, film defects, and damage to the mating sheet) are solved all at once, mainly for optical applications. Can be manufactured industrially advantageously.

[0022]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, “parts” means “parts by weight”.

Example 1 FIG. 1 is an explanatory view showing an example of the manufacturing method of the present invention.

As an example of the substrate sheet (1), a thickness of 42 μm
A phase plate having a total thickness of 208 μm was prepared in which both sides of a retardation film made of m 1 uniaxially stretched polyvinyl alcohol film were protected with a cellulose triacetate film.
As the releasable sheet (2), a polyester film (biaxially stretched polyethylene terephthalate film) having a thickness of 38 μm, which was subjected to a release treatment with a silicone-based release agent on one surface, was prepared.

Further, as a fluid non-solvent type high-viscosity adhesive resin composition (a) for forming the adhesive layer (A), butyl acrylate-vinyl acetate (weight ratio 6%) is used.
5:35) 170 parts of copolymer with 1 part of butyl acrylate
A resin liquid having a viscosity of 11500 cps / 20 ° C., which was composed of 5 parts, 5 parts of vinyl acetate, 10 parts of acrylic acid and 2 parts of benzoin isobutyl ether (photopolymerization initiator), was prepared.

The substrate sheet (1) and the releasable sheet (2) prepared above are supplied to a pair of rolls arranged in parallel with a slight gap (the releasable sheet (2) is With the release treated surface facing up), while ejecting the composition (a) above toward the gap between the rolls, rotate both rolls in the direction of biting into each other and release from the base sheet (1). The composition (a) was sandwiched between the composition sheet and the property sheet (2). Then, in such a sandwiched state, the composition (a) was cured by irradiation with ultraviolet rays under the conditions of an output of 120 W / cm, a lamp distance of 150 mm, and an integrated light amount of 600 mJ / cm ² . As a result, a sheet having a layer structure of the substrate sheet (1) / the pressure-sensitive adhesive layer (A) / the release sheet (2) was obtained. Thickness of adhesive layer (A) is 30μm
Met.

While the release sheet (2) was peeled off from this sheet, the release sheet was attached to a liquid crystal cell.
The peeling of (2) was smooth, the adhesive layer (A) was transferred onto the base material sheet (phase plate) (1) cleanly, and the sticking operation to the liquid crystal cell was also smooth.

Example 2 As an example of the substrate sheet (1), a total thickness of 205 μm obtained by protecting both sides of a polyvinyl alcohol-iodine type polarizing element film having a thickness of 35 μm with a cellulose triacetate film.
A m polarizing plate was prepared. Also, as the release sheet (2),
A 25 μm-thick polyester film (biaxially stretched polyethylene terephthalate film) having one surface subjected to a release treatment with a silicone-based release agent was prepared.

Further, as a fluid non-solvent type high-viscosity adhesive resin composition (a) for forming the adhesive layer (A), 2-ethylhexyl acrylate-methyl methacrylate-acrylic acid (70:20 by weight ratio) is used. : 10) A resin liquid having a viscosity of 5500 cps / 20 ° C. was prepared by adding 160 parts of a copolymer to 20 parts of butyl acrylate, 10 parts of methyl methacrylate, 10 parts of acrylic acid and 3 parts of benzoin isobutyl ether (photopolymerization initiator).

Thereafter, in the same manner as in Example 1, the substrate sheet
A sheet having a layer structure of (1) / adhesive layer (A) / releasing sheet (2) was obtained. The pressure-sensitive adhesive layer (A) had a thickness of 25 μm.

While the releasable sheet (2) was peeled off from this sheet, it was attached to a liquid crystal cell.
The peeling of (2) was smooth, the pressure-sensitive adhesive layer (A) was transferred onto the substrate sheet (polarizing plate) (1) cleanly, and the sticking operation to the liquid crystal cell was also smooth.

[0032]

As described in the description of the operation, in the present invention, since a special film forming method using a pair of rolls is adopted, various problems which have been a concern in the conventional coating method are adopted. Problems (dust adhesion, work environment deterioration, utility disadvantage, equipment cost disadvantage, equipment occupation space disadvantage, line speed restriction, curl occurrence, film defect occurrence, partner sheet damage ) Is solved all at once, and a sheet mainly for optical use having an adhesive layer can be industrially advantageously manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a production method of the present invention.

[Explanation of symbols]

 (1) ... Substrate sheet, (2) ... Releasable sheet, (A) ... Adhesive layer, (a) ... High viscosity adhesive resin composition

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02F 1/13 101 G02F 1/13 101 1/1335 510 1/1335 510

Claims (3)

[Claims] 1. A base material sheet (1) and a releasable sheet (2) are supplied to a pair of rolls arranged in parallel with a slight gap, and the pressure-sensitive adhesive layer is directed toward the roll gap. (A) The base sheet (1) and the releasable sheet are discharged by ejecting the flowable non-solvent type high-viscosity adhesive resin composition (a) for forming, and rotating both rolls in a direction to bite each other. A method for producing a sheet having a pressure-sensitive adhesive layer, characterized in that the high-viscosity pressure-sensitive adhesive resin composition (a) is sandwiched between (2) and the pressure-sensitive adhesive layer (A). 2. A non-solvent type high-viscosity adhesive resin composition (a) contains a component which is cured by heating or irradiation with active energy rays, and comprises a base sheet (1) and a release sheet (2). After the high-viscosity adhesive resin composition (a) is sandwiched between them, the adhesive layer is formed by taking a curing means for the high-viscosity adhesive resin composition (a) in such a sandwiched state. The method according to claim 1, wherein (A) is used. 3. The method according to claim 1, wherein the base sheet (1) is a single-layer or multi-layer optical sheet.