JP2003207637A - Polarizing plate and polarizing plate with tacky adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate which is formed by using general protective films or angle-of-view improving films and is small in void even if a relatively hard tacky adhesive is used and to provide a polarizing plate with a tacky adhesive imparted with a tacky adhesive layer thereto. <P>SOLUTION: The polarizing plate which is formed by laminating the protective films consisting of a resin different from a polyvinyl alcohol (PVA) resin on both surfaces of the polarizing film consisting of the PVA resin adsorbed and oriented with dichromatic dyestuffs and having a thickness over 10 μm and below 20 μm is provided. The polarizing plate with the tacky adhesive which is formed by imparting the tacky adhesive layer of ≤30 μm in the deviation value after 100 seconds and ≤50 μm in the deviation value after 1,000 seconds in a deviation test to at least one surface of the polarizing plate and which is ≤3.5 in the ratio K<SB>2</SB>/K<SB>1</SB>of the brightness K<SB>1</SB>in the central part of the polarizing plate and the brightness K<SB>2</SB>in the central edge segment on the long side of the polarizing plate when two sheets of the polarizing plate each sized 200 mm×150 mm are superposed in crossed Nicols is also provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polarizing plate and a polarizing plate with an adhesive.

[0002]

2. Description of the Related Art A polarizing plate is usually manufactured by laminating a protective film on both sides of a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film, and an adhesive layer is provided on at least one side of the polarizing film. In the form, it is used as a material for liquid crystal display elements. As a protective film, a triacetyl cellulose film is most widely used because of its good optical characteristics and good appearance.

However, the current polarizing plate is not one in which its characteristics are never satisfactory. For example, a polarizing plate whose optical axis is chip-cut at an angle of 45 ° or 135 ° with respect to the long side direction of the product is used. When it is attached to both sides of the liquid crystal display device via the adhesive layer and left in a harsh environment such as 80 ° C drying conditions, light leakage is observed near the central edges of the long and short sides of the polarizing plate. The so-called "blank"
The problem arises. In order to reduce white spots in the polarizing plate, for example, JP-A-6-51117 proposes to use a protective film having a small photoelastic coefficient,
As a resin having a small photoelastic coefficient, a thermoplastic cyclic polyolefin resin is known. Further, JP-A-9-87593 proposes to use a soft pressure-sensitive adhesive in order to reduce white spots in the polarizing plate.

However, when the protective film is changed, the optical properties of the protective film are often inferior to those of the triacetyl cellulose film. There is a problem that the process needs to be changed and the cost is increased. In recent years, in order to expand the viewing angle of liquid crystal display devices,
Although there is a demand for a polarizing plate in which a viewing angle improving film is directly attached to a polarizing film, the viewing angle widening film is usually composed of a triacetyl cellulose film provided with a cholesteric liquid crystal layer. As long as it is used, the effect of reducing white spots cannot be expected by using a resin film having a smaller photoelastic coefficient than triacetyl cellulose. On the other hand, when a relatively soft adhesive is used, the adhesive may be damaged at the film edge during chip cutting, or the adhesive remains attached to the liquid crystal cell side when the polarizing plate is peeled from the liquid crystal cell. In many cases, the problem of "paste residue" occurs.

[0005]

Therefore, even when a protective film or a viewing angle improving film which has been conventionally used is used and an adhesive having a certain degree of hardness is used, a polarizing plate with a small blank area is obtained. Was desired to be developed. Therefore, the present inventors have conducted earnest research to meet such a demand, and found that this problem can be solved by reducing the thickness of a polarizing film made of a polyvinyl alcohol-based resin film. The present invention was achieved by conducting various studies on a polarizing plate with a pressure-sensitive adhesive, in which a pressure-sensitive adhesive layer was provided on a polarizing plate having protective films laminated on both sides of the film.

[0006]

That is, according to the present invention, a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented and having a thickness of more than 10 μm and 20 μm or more is used.
Provided is a polarizing plate in which a resin film different from a polyvinyl alcohol-based resin is bonded as a protective film on both surfaces of a polarizing film having a size of less than m 2.

A pressure-sensitive adhesive layer can be provided on one side or both sides of this polarizing plate to form a polarizing plate with a pressure-sensitive adhesive which can be attached to other members. At this time, the pressure-sensitive adhesive layer has specific physical properties. By using a material having the above, it is possible to reduce so-called white voids in the polarizing plate, and it is also possible to solve problems such as so-called adhesive residue when the polarizing plate is once attached and then peeled off. Therefore, according to the present invention, a pressure-sensitive adhesive layer is provided on at least one surface of the above polarizing plate, in which a deviation amount after 100 seconds in a deviation amount test is 30 μm or less and a deviation amount after 1,000 seconds is 50 μm or less. The ratio K ₂ / K of the brightness K _{1 at the} central part of the polarizing plate and the brightness K ₂ at the central edge of the long side of the polarizing plate when two polarizing plates of 200 mm × 150 mm size are stacked by crossed Nicols. Also provided is a polarizing plate with an adhesive, wherein ₁ is 3.5 or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The polarizing film constituting the polarizing plate is a polyvinyl alcohol-based resin film dyed with a dichroic dye and uniaxially stretched, and the dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin film.

Examples of the polyvinyl alcohol resin as a raw material include those obtained by saponifying a polyvinyl acetate resin. The polyvinyl acetate-based resin includes, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, vinyl acetate and copolymers of other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, vinyl ethers and unsaturated sulfonic acids. The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 to 100 mol%.
And more preferably 99 from the viewpoint of optical characteristics.
It is at least mol%. The polyvinyl alcohol-based resin may be further modified, and examples of the modified polyvinyl alcohol-based resin include aldehyde-modified polyvinyl formal and polyvinyl acetal.

The degree of polymerization of polyvinyl alcohol resin is
Usually 1,000 to 10,000, preferably 1,500 to
10,000, more preferably 2,000 to 10,000
The range is 0. The polyvinyl alcohol-based resin film preferably contains a plasticizer such as glycerin in the range of about 5 to 20% by weight. In the conventional method, a polyvinyl alcohol-based film original film having a film thickness of about 75 μm has been used, but in the present invention, it is preferable to use a polyvinyl alcohol-based resin film of 25 to 50 μm as an original film. The thickness of the raw film is more preferably 30 μm or more and 45 μm or less.

For the polarizing film, a step of dyeing a polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye, and treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with an aqueous boric acid solution It is manufactured through a step and a step of uniaxially stretching a polyvinyl alcohol resin film. The uniaxially stretching step may be performed before, after, or during the series of steps, but is generally performed before the dyeing, during the dyeing step, or during the boric acid treatment step. Usually, washing and drying are carried out after the treatment with the boric acid aqueous solution. A protective film is attached to both surfaces of this polarizing film to form a polarizing plate.

To dye a polyvinyl alcohol resin film with a dichroic dye, for example, this film may be dipped in an aqueous solution containing the dichroic dye. As the dichroic pigment, iodine or a dichroic organic dye is used.

When iodine is used as the dichroic dye, the polyvinyl alcohol resin film may be dipped in an aqueous solution containing iodine and potassium iodide.
The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 100 parts by weight of water.
It is about 10 parts by weight. The temperature of the dyeing bath containing iodine and potassium iodide is usually about 20 to 40 ° C,
Further, the immersion time there is usually about 30 to 300 seconds.

When a dichroic dye is used as the dichroic dye, the polyvinyl alcohol resin film may be dipped in an aqueous solution of the dichroic dye. The content of the dichroic dye in this aqueous solution is usually 1 × 1 per 100 parts by weight of water.
It is about 0 ⁻³ to 1 × 10 ⁻² parts by weight. The dichroic dyes may be used alone or in combination of two or more. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of the dyeing bath containing the dichroic dye is usually about 20 to 80 ° C., and the immersion time therefor is usually about 30 to 300 seconds.

The boric acid treatment is carried out, for example, by immersing a polyvinyl alcohol resin film dyed with a dichroic dye in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually about 2 to 15 parts by weight, preferably 5 parts by weight or more, per 100 parts by weight of water.
It is preferably 12 parts by weight or less. The temperature of the boric acid aqueous solution is usually 50 ° C or higher, preferably 60 ° C or higher, more preferably 68 ° C or higher, and preferably 85 ° C.
The temperature is below 80 ° C. The immersion time there is usually about 100 to 1,200 seconds, preferably 150 seconds or longer, more preferably 200 seconds or longer, and preferably 600 seconds or shorter, further 500 seconds or shorter.

When the dichroic dye is iodine, the boric acid aqueous solution may contain potassium iodide. When potassium iodide is contained, the amount thereof is usually about 2 to 20 parts by weight, preferably 5 parts by weight or more, and preferably 15 parts by weight or less, per 100 parts by weight of water.

The polyvinyl alcohol-based resin film treated with boric acid is usually washed with water thereafter. The water washing treatment is performed, for example, by immersing the polyvinyl alcohol resin film after the boric acid treatment in water. The temperature of water in the washing process is usually about 5 to 40 ° C,
The immersion time is usually 2 to 120 seconds. Next, a drying treatment is carried out. The temperature of the drying treatment is usually 100 ° C. or lower, preferably 40 ° C. or higher, and preferably 95 ° C. or lower. The drying treatment time is usually about 120 to 600 seconds.

The uniaxial stretching of the polyvinyl alcohol-based resin film is generally carried out before dyeing, during the dyeing process or during the boric acid treatment process, as described above, and the stretching may be carried out at a plurality of these stages. When uniaxially stretching before dyeing, it is usually performed by a dry method, for example, under a heating atmosphere, a method of uniaxially stretching between rolls having different peripheral speeds, or uniaxial compression stretching by passing between hot rolls. The method etc. can be applied. Further, transverse uniaxial stretching such as the tenter method can also be adopted. On the other hand, when carrying out uniaxial stretching during the dyeing step or the boric acid treatment step, it is immersed in a dyeing bath or a boric acid treatment bath, and swollen by these baths, for example, successively passed through rolls with different peripheral speeds. It will be wet-stretched. The total draw ratio from the raw material of the polyvinyl alcohol resin film to the polarizing film is usually about 4 to 8 times, preferably 4.5 times or more, and more preferably 4.8 times or more. Yes, and preferably 6.5
It is less than or equal to double, and further less than or equal to six.

The inventors of the present invention have studied the measures for reducing the "white spot" of the polarizing plate, and have found that the thinner the polarizing film is, the greater the white spot reducing effect of the polarizing plate. However, it has been found that when the film is made too thin, the strength of the film is lowered and the film often breaks during the process of obtaining the polarizing film. Therefore, as a result of further research, the film thickness of the polarizing film was 10 μm.
It has been found that when the thickness exceeds about 20 μm and is less than about 20 μm, the film is not broken and a film having a whiteout reduction effect can be obtained by appropriately selecting the conditions in the middle. The conditions of the above-mentioned various treatments are appropriately selected within a range in which the film is not broken, but it is necessary to select such conditions that various properties and appearance of the obtained polarizing film are not inferior to those of a normal polarizing film.

The polarizing film thus obtained is laminated with protective films on both sides thereof to form a polarizing plate. This protective film is a resin film of a different type from the polyvinyl alcohol-based resin which is a polarizing film, and for example, a cellulose acetate resin film such as triacetyl cellulose or diacetyl cellulose, an acrylic resin film, a polyester resin film, a polyarylate resin. Film, polyethersulfone resin film,
A thermoplastic cyclic polyolefin resin film or the like is used. Its thickness is usually about 30 to 200 μm.
For the lamination of the protective film, a transparent and optically isotropic adhesive is usually used. Examples of such an adhesive include:
Examples thereof include polyvinyl alcohol adhesives and polyester polyurethane adhesives.

If the optical properties and the appearance quality are similar to those of conventional triacetyl cellulose, the protective film can be laminated at a cost comparable to that of triacetyl cellulose and has a small photoelastic coefficient, for example, a thermoplastic cyclic polyolefin. If a protective film such as a resin film is present, the effect of reducing white spots is further enhanced by the synergistic effect of using the thin polarizing film according to the present invention. Therefore, using a protective film made of a resin having a photoelastic coefficient of 5 × 10 ⁻¹³ cm ² / dyn or less is effective in one aspect.

On the other hand, according to the present invention, even if a protective film having a photoelastic coefficient of 5 × 10 ⁻¹³ cm ² / dyn or more, such as a commonly used triacetyl cellulose film, is used as a conventional product. Compared with this, it shows a significant white spot reduction effect. In particular, the triacetyl cellulose film has been widely used as a protective layer for a polarizing film, as described above, and is excellent in optical properties such as transparency and low birefringence under no stress. Among the resins exemplified above as the protective film, most of the resins other than the thermoplastic cyclic polyolefin resin film have a photoelastic coefficient of 5 × 10 ⁻¹³ cm ² / dyn or more, and thus, they have been conventionally used. If the protective film is not changed, the laminating step can be adopted as it is, and white spots can be effectively reduced. Therefore, the present invention is also effective in that respect.

Incidentally, photoelasticity means isotropic property, that is, when an external force is applied to a substance having a birefringence of 0 to cause stress inside, it exhibits optical anisotropy and exhibits birefringence. A phenomenon. If the stress acting on the substance (force acting on a unit area) is σ and the birefringence is Δn, the stress σ
And the birefringence Δn are theoretically proportional to each other, and Δn = C
It can be expressed as σ, and this C is the photoelastic coefficient. In other words, when the stress σ acting on a substance is plotted on the horizontal axis and the birefringence Δn when the stress acts is plotted on the vertical axis, theoretically the relationship between the two becomes a straight line, and the gradient of this straight line is the photoelasticity. It is a coefficient.

A protective film having a different base resin may be attached to each surface of the polarizing film. Also,
A functional layer may be provided on the base film. A typical protective film having a functional layer is a viewing angle improving film having a discotic liquid crystal layer on a triacetyl cellulose film, and is typically sold by Fuji Photo Film Co., Ltd. "WV
The present invention is very suitable when a protective film based on triacetyl cellulose film such as “WV film” has to be used.

On the surface of the polarizing plate, a hard coat layer,
It may have various functional layers such as an antireflection layer and an antiglare layer. Further, a protective film for surface protection may be attached to the outermost surface of the polarizing plate.

A pressure-sensitive adhesive layer is provided on at least one surface of the polarizing plate. Examples of such a pressure-sensitive adhesive include acrylic acid-based adhesives,
Adhesives using base polymers such as methacrylic acid type, butyl rubber type, and silicone type can be used. Although not particularly limited, (meth) acrylate base polymers such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, A copolymer base polymer using two or more kinds of these (meth) acrylic acid esters is preferably used. In adhesives, polar monomers are usually copolymerized in these base polymers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate and glycidyl (meth) acrylate.

The pressure-sensitive adhesive usually contains a crosslinking agent. As the cross-linking agent, a compound that forms a divalent or polyvalent metal ion and a carboxylic acid metal salt, a compound that forms an amide bond with a polyamine compound, a compound that forms an ester bond with a polyepoxy compound or a polyol, a polyisocyanate compound and an amide Examples thereof include those that form a bond, and these compounds are used as a cross-linking agent by mixing one or more kinds with the base polymer.

The thickness of a general pressure-sensitive adhesive layer is 2 to 50 μm.
It is a degree. In the usual form, a separate film is attached to the surface of the adhesive layer opposite to the polarizing plate for the purpose of protecting the adhesive layer. As the separate film, a polyester film which has been subjected to a release treatment with a silicone resin or the like is used. This separate film is peeled and removed at the time of bonding with a liquid crystal cell or another optically functional film.

In the pressure-sensitive adhesive-attached polarizing plate of the present invention, it is not necessary to soften the pressure-sensitive adhesive layer in order to prevent white spots, and a relatively hard pressure-sensitive adhesive known so far can be used.
As an index showing the softness of the pressure-sensitive adhesive, the amount of deviation and the relaxation elastic modulus can be used.

The amount of deviation of the pressure-sensitive adhesive layer can be determined by laminating the pressure-sensitive adhesive-attached polarizing plate on a glass plate in the state shown in FIG. 1 and generating a shearing force with a predetermined load. That is, FIG. 1 schematically shows the configuration of a sample used for measuring the amount of deviation, where (A) is a front view,
(B) is a side view. First, a polarizing plate 2 with an adhesive, which has a rectangular shape with a short side length of 25 mm, is prepared. The pressure-sensitive adhesive-attached polarizing plate 2 has a pressure-sensitive adhesive layer 3 provided on one surface of a polarizing plate 4. Then, the part 5 of the adhesive layer up to the end 25 mm is attached to the glass plate 1. In this state, the end 25 mm × 25 mm portion 5 of the pressure-sensitive adhesive layer 3 is bonded to the glass plate, and the remaining portion of the pressure-sensitive adhesive layer protrudes from the glass plate. In this state, it is left to stand in a room having a relative humidity of 60% at about 25 ° C. for about 1 hour. Next, a load of 1 kg is attached to a portion of the polarizing plate with adhesive 2 that is not attached to the glass plate 1, the glass plate 1 is fixed, and the glass plate 1 is suspended as shown in FIG. Then, the elapsed time after load application and the amount of deviation of the film are measured. A device capable of measuring with an accuracy of 1 μm or less is used to measure the amount of film deviation.

The amount of deviation of the pressure-sensitive adhesive layer thus measured is
If it is about 30 μm or less, preferably 25 μm or less after 100 seconds from the start of suspension of the load, and about 50 μm or less, preferably about 40 μm or less after 1,000 seconds, problems such as adhesive residue are generally unlikely to occur. Therefore, in the pressure-sensitive adhesive-attached polarizing plate of the present invention, the deviation amount after 100 seconds in the deviation amount test is 30 μm or less, and the deviation amount after 1,000 seconds is 50 μm.
The following adhesive layer is used.

Next, the relaxation elastic modulus will be described. Generally, when the strain γ ₀ is momentarily applied to the viscoelastic body and then it is kept constant, the stress σ (t) decreases with time t and becomes constant. It approaches the value and this is called stress relaxation. At this time, the stress σ (t) that relaxes with the passage of time t can be expressed as σ (t) = G (t) · γ ₀ . G (t) is the elastic modulus depending on the time t, and this is called the relaxation elastic modulus. This equation can be rewritten as G (t) = σ (t) / γ ₀ , so the relaxation elastic modulus G (t) is
It is the ratio of the stress σ (t) that decreases with time t and the constant strain γ ₀ applied from the outside.

Thus, the relaxation elastic modulus G (t) is
The relaxation elastic modulus G (100) after 100 seconds is
When it is in the range of 3 × 10 ^{5 to} 5 × 10 ⁶ dyn / cm ² , it is good from the viewpoint of eliminating white spots, but when the value is relatively low even within this range, adhesive residue and reworkability may be deteriorated. Inferior in terms. Therefore, the relaxation elastic modulus G (100) after 100 seconds is
The range of 6 × 10 ^{5 to} 5 × 10 ⁶ dyn / cm ² is preferable in terms of adhesive residue and reworkability, and further 6.5 ×
More preferably, it is in the range of 10 ^{5 to} 5 × 10 ⁶ dyn / cm ² .

The pressure-sensitive adhesive-attached polarizing plate of the present invention is characterized in that such adhesive residue is unlikely to occur, that is, white spot defects are considerably reduced while using a pressure-sensitive adhesive having a relatively hard viscoelastic property. It has major characteristics.

Then, the whiteout index of the polarizing plate will be described. For the measurement of the whiteout index, a polarizing plate with an adhesive attached to a glass plate in the state shown in FIG. 2 is used. That is, FIG. 2 schematically shows the configuration of a sample used for measuring the whiteout index, where (A) is a plan view and (B) is a side view. First, the polarizing plate with adhesive 2
It is cut into a predetermined size so that the absorption axis of is oriented at 45 degrees to the long side. The pressure-sensitive adhesive-attached polarizing plate 2 has a pressure-sensitive adhesive layer 3 provided on one surface of a polarizing plate 4. Two sheets of the polarizing plate 2 with the pressure-sensitive adhesive are used, and these are laminated on both surfaces of the transparent glass plate 1 so as to be crossed nicols, that is, so that the absorption axes of the two polarizing plates 4 and 4 are orthogonal to each other. In this way, the glass plate 1 on which the two polarizing plates 2 with an adhesive are attached is placed in an oven, and the glass plate 1 is placed under a dry heat condition of 80 ° C. for 24 hours.
Leave for 0 hours. The sample after being held under the dry heat condition was taken out from the oven, placed on the backlight light source device, and the brightness K _{1 of the} central portion of the polarizing plate indicated by the symbol M in FIG. The luminance K ₂ at the central edge portion of the long side of the polarizing plate shown is measured. The void index is the following formula (I)
Calculate with.

Whiteout index = K ₂ / K ₁ (I)

Usually, K ₁ <K ₂ , but the ideal whiteout index is 1.0, and the closer the value is to 1, the greater the whiteout reduction effect. Conversely, the larger the whiteout index, the larger the whiteout. Since the whiteout index tends to increase as the size of the sample increases, it is necessary to test the sizes of the samples in order to compare the whiteout reduction effect. And according to the present invention, 200 mm × 150
White area index K ₂ / K ₁ when using mm size polarizing plate
However, not only immediately after the production, but also after holding for 240 hours under the dry heat condition of 80 ° C. as described above, it can be set to 3.5 or less.

The polarizing plate with an adhesive of the present invention has a photoelastic coefficient of 5 like a triacetyl cellulose film.
Even when a resin film having a density of × 10 ^-13 cm ² / dyn or more is used as a protective film, it is advantageous because white spots can be considerably reduced as described above. Further, a protective film by directly bonding a functional film formed of a triacetyl cellulose film base, such as a triacetyl cellulose film having a discotic liquid crystal layer on one surface, to a polyvinyl alcohol-based polarizing film layer. Even in the case of doing so, it is also advantageous because the white spots can be similarly reduced to a considerable extent.

[0039]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The evaluation method in each example is as follows.

[Measurement of the amount of displacement of the adhesive layer] 1. As shown in FIG. 1, 25 soda lime glass plate 1
mm × 80 mm polarizing plate 2 with adhesive, one end of which is 25 mm ×
Laminated on 25 mm part 5, 60% relative humidity at about 25 ° C
Leave it in the room for about 1 hour. 2. A load of 1 kg is attached to a portion of the polarizing plate with adhesive 2 that is not attached to the glass 1, the glass plate 1 is fixed, and the glass plate 1 is hung as shown in FIG. 3. Measure the elapsed time after the start of load suspension and the amount of film deviation. A device capable of measuring with an accuracy of 1 μm or less is used to measure the amount of film deviation.

[Measurement of Relaxation Elastic Modulus] An elastic modulus measuring device “Rheometrics RDS-II” was used for a sample with a thickness of 1 mm obtained by laminating only an adhesive layer used for producing a polarizing plate with an adhesive.
(Rheometrics Co., Ltd.) is used to measure the relaxation elastic modulus G (100) at a standard temperature of 25 ° C. and a relaxation time of 100 seconds.

[Measurement of White Area Index] 1. As shown in FIG. 2, 200 mm × 150 mm so that the absorption axis of the polarizing plate with adhesive 2 is oriented at 45 ° to the long side.
Cut into rectangles. 2. Two sheets of the polarizing plate 2 with the pressure-sensitive adhesive are used, and these are laminated on both surfaces of the transparent glass plate 1 so as to form crossed Nicols. 3. In this way, the glass plate 1 on which the two polarizing plates 2 with an adhesive are attached is placed in an oven, and the glass plate 1 is placed under a dry heat condition of 80 ° C. for 24 hours.
Leave for 0 hours. 4. After being held under the dry heat condition, the sample was taken out from the oven and placed on a backlight source device, as shown in FIG.
In (A), the brightness K _{1 at the} central part of the polarizing plate indicated by the symbol M and the brightness K _{2 at the} central edge part of the long side of the polarizing plate also indicated by the symbol E
To measure. From these values, the white spot index K ₂ / K ₁ is determined.

Example 1 A polymerization degree of 2,400, a saponification degree of 99 mol% or more, and a thickness of 3
A 7.9 μm polyvinyl alcohol film was hot-roll stretched at a hot roll temperature of 115 ° C. and a draw ratio of 4.9 times. The film thickness of the stretched film was 8.6 μm. Iodine was added to this stretched film in an amount of 0.0 per 100 parts by weight of water.
28 ° C containing 6 parts by weight and 5 parts by weight of potassium iodide
The sample was immersed in the above aqueous solution under constant tension for 60 seconds to adsorb iodine. Next, add boric acid to 100 parts by weight of water.
It was dipped in a boric acid aqueous solution containing 3 parts by weight and 6.5 parts by weight of potassium iodide at a temperature of 71 ° C. for 300 seconds at a constant tension. Then, it was washed with pure water at 25 ° C. for 10 seconds. Keep the tension of the film after washing with water at 50 ° C for 300
After drying for 2 seconds, a polarizing film having a film thickness of 12.5 μm was obtained.

Polyvinyl alcohol adhesives were applied to both sides of this polarizing film, and the respective adhesive application surfaces were
A triacetyl cellulose film having a saponified surface and a thickness of 80 μm protective film (“Fujitac UV80” manufactured by Fuji Photo Film Co., Ltd.)
It was dried at 0 ° C. for 5 minutes to obtain a polarizing plate. The photoelastic coefficient of triacetyl cellulose film is 8.0 × 10 ^-13 cm ²
It was / dyn.

An acrylic adhesive was applied to one surface of this polarizing plate to give a polarizing plate with an adhesive. The thickness of the adhesive is 23μ
It was m. In this case, the amount of displacement of the pressure-sensitive adhesive layer was 21 μm after 100 seconds from the start of load suspension and 28 μm after 1,000 seconds, and the relaxation elastic modulus G (100) of this pressure-sensitive adhesive was measured.
Was 4.0 × 10 ⁵ dyn / cm ² . The white spot index K ₂ / K ₁ of this polarizing plate with an adhesive was 3.2.

On the other hand, one sheet of the pressure-sensitive adhesive-attached polarizing plate obtained above was laminated on glass and treated for 30 minutes in an autoclave at a temperature of 50 ° C. and a pressure of 49 N / cm ² , and then the polarizing plate was made into a glass. I stripped it off. No adhesive was attached to the glass surface, and no adhesive residue remained.

Example 2 A polarizing plate with an adhesive was prepared in the same manner as in Example 1 except that a cyclic polyolefin resin film having a thickness of 40 μm was used as a protective film and a polyester polyurethane adhesive was used for adhesion to the polarizing film. It was made. The photoelastic coefficient of the cyclic polyolefin resin film used here is
It was 3.0 × 10 ⁻¹³ cm ² / dyn. The white spot index K ₂ / K ₁ of this polarizing plate with an adhesive was 1.6.

COMPARATIVE EXAMPLE 1 Except that the raw polyvinyl alcohol had a thickness of 75 μm (the degree of polymerization and the degree of saponification were the same as in Example 1).
The same operation as in Example 1 was performed to prepare a polarizing film having a film thickness of 23.6 μm. These conditions are almost the same as those of the commercially available polarizing film manufacturing method. Using this polarizing film, a polarizing plate with an adhesive was prepared and evaluated in the same manner as in Example 1. The white spot index K ₂ / K ₁ was 4.8. No adhesive residue was observed.

Comparative Example 2 A polarizing plate was prepared in the same manner as in Example 1. The amount of deviation 100 seconds after the start of load suspension is 4
An adhesive having a deviation of 4 μm after 1,000 seconds of 83 μm and a relaxation elastic modulus G (100) of 2.1 × 10 ⁵ dyn / cm ² was applied to obtain a polarizing plate with an adhesive. White area index K ₂ / K ₁
Was 3.2, which was better than that of the pressure-sensitive adhesive-attached polarizing plate of Comparative Example 1, but adhesive residue was observed in the peel test.

[0050]

EFFECTS OF THE INVENTION According to the present invention, so-called adhesive residue when white spots are reduced and the adhesive film is peeled off after being attached to a liquid crystal cell while using a general protective film which has been conventionally used It is possible to obtain a polarizing plate with an adhesive in which problems such as the above have been solved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration of a sample used for measuring a displacement amount of an adhesive layer, in which (A) is a front view and (B) is a side view.

2A and 2B are views for explaining the configuration of a sample used for measuring a white blank index, FIG. 2A is a plan view, and FIG. 2B is a side view.

[Explanation of symbols]

1 ... Glass plate, 2 ... Adhesive-attached polarizing plate, 3 ... Adhesive layer, 4 ... Polarizing plate, 5 ... Displacement amount measurement sample pasted part (25 mm × 25 m)
m).

Continued front page    F-term (reference) 2H049 BA02 BA27 BB33 BB43 BB51                       BC03 BC10                 2H091 FB02 FC05 FC08 FC29 FD09                       FD14 GA16 GA17 LA03 LA04                       LA11 LA12 LA13 LA16                 4J004 AA06 AA08 AA10 AB01 CA04                       CB03 CC02 FA01                 4J040 DA141 DF011 DF041 DF051                       DF091 EK031 GA05 GA07                       GA11 GA15 GA22 JA09 JB09                       MB03 NA17 PA23

Claims (6)

[Claims] 1. A polarizing film comprising a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented and having a thickness of more than 10 μm and less than 20 μm is protected by a resin film of a different type from the polyvinyl alcohol-based resin. A polarizing plate, which is laminated as a film. 2. A polarizing film having a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented and having a thickness of more than 10 μm and less than 20 μm is protected by a resin film of a different type from the polyvinyl alcohol-based resin. At least one surface of the polarizing plate laminated as a film has a deviation amount of 3 after 100 seconds in the deviation amount test.
A pressure-sensitive adhesive layer with a deviation of 50 μm or less after 1,000 seconds at a thickness of 0 μm or less is provided, and a 200 mm × 150 mm size polarizing plate is formed at the center of the polarizing plate when two sheets are stacked with crossed Nicols. A polarizing plate with an adhesive, characterized in that the ratio K ₂ / K _{1 of the} brightness K ₁ and the brightness K ₂ of the central portion of the long side of the polarizing plate is 3.5 or less. 3. The relaxation elastic modulus G (10) of the adhesive layer after 100 seconds.
The pressure-sensitive adhesive-attached polarizing plate according to claim ² , wherein 0) is 6 × 10 ^{5 to} 5 × 10 ⁶ dyn / cm ² . 4. The pressure-sensitive adhesive-attached polarizing plate according to claim 2, wherein the protective film has a photoelastic coefficient of 5 × 10 ⁻¹³ cm ² / dyn or more. 5. The pressure-sensitive adhesive-attached polarizing plate according to claim 4, wherein the protective film is a triacetyl cellulose film. 6. The polarizing plate with a pressure-sensitive adhesive according to claim 5, wherein one of the protective films is a triacetyl cellulose film having a discotic liquid crystal layer on one surface thereof.