阅读说明：本技术 偏光板及包含其的图像显示装置 (Polarizing plate and image display device comprising same ) 是由 金孝东 朴旼奎 赵天熙 于 2018-12-26 设计创作，主要内容包括：本发明的实施例提供一种偏光板,其包含偏振片以及形成于上述偏振片的至少一面的保护基材,上述保护基材包含保护膜和阻挡层的层叠体,上述阻挡层包含特定重复单元。由此,水分透过度低,并且能够在常温、高湿或高温、高湿条件下显著防止偏光板的弯曲,有效防止漏光发生。(An embodiment of the present invention provides a polarizing plate including a polarizing plate and a protective substrate formed on at least one surface of the polarizing plate, wherein the protective substrate includes a laminate of a protective film and a barrier layer, and the barrier layer includes a specific repeating unit. This can significantly prevent the polarizer from being bent under normal temperature, high humidity, or high temperature, high humidity conditions, and thus can effectively prevent light leakage.)

1. A polarizing plate, comprising:

a polarizing plate; and

a protective substrate formed on at least one surface of the polarizing plate,

the protective substrate comprises a laminate of a protective film and a barrier layer,

the barrier layer includes a repeating unit represented by the following chemical formula 1,

[ chemical formula 1]

In the formula, R₁And R₂Each independently hydrogen or an alkyl group of 1 to 6 carbon atoms, and n is an integer of 10 to 1,000,000.

2. The polarizing plate of claim 1, wherein the barrier layer has a storage modulus of 500 to 2,000MPa at 80 ℃.

3. The polarizing plate of claim 1, wherein the protective substrate has a moisture permeability of 5 to 50g/m measured at 90% relative humidity and 40 ℃ after 24 hours²Day.

4. The polarizing plate of claim 1, wherein the barrier layer has a thickness of 0.05nm to 5 μm.

5. The polarizing plate according to claim 1, wherein the protective film is disposed so that the barrier layer faces the polarizer,

an adhesive layer is further interposed between the polarizer and the barrier layer.

6. A polarizing plate, comprising:

a polarizing plate; and

a first protective film and a second protective film respectively formed on both surfaces of the polarizing plate,

the first protective film is arranged on the visible side and one surface of the first protective film is adhered with a barrier layer,

the barrier layer includes a repeating unit represented by the following chemical formula 1,

[ chemical formula 1]

In the formula, R₁And R₂Each independently hydrogen or an alkyl group of 1 to 6 carbon atoms, and n is an integer of 10 to 1,000,000.

7. The polarizing plate of claim 6, wherein the barrier layer has a storage modulus of 500 to 2,000MPa at 80 ℃.

8. The polarizing plate according to claim 6, further comprising a first adhesive layer interposed between the polarizer and the first protective film and a second adhesive layer interposed between the polarizer and the second protective film.

9. The polarizing plate according to claim 8, wherein the barrier layer is disposed so as to face the polarizer,

the first adhesive layer is interposed between the polarizing plate and the barrier layer.

10. The polarizing plate according to claim 8, wherein the first adhesive layer is formed from a first adhesive composition comprising an acetoacetyl-modified polyvinyl alcohol resin, a glyoxal cross-linking agent, and a water-soluble salt of two or more polyvalent metal ions,

the second adhesive layer is formed from a second adhesive composition containing an acetoacetyl-modified polyvinyl alcohol resin and an aziridine crosslinking agent.

11. An image display device comprising the polarizing plate according to any one of claims 1 to 10.

Technical Field

The present invention relates to a polarizing plate and an image display device including the same.

Background

The image display device may include a display panel and polarizing plates respectively formed on both surfaces of the display panel. The polarizing plate may include a polarizer and protective films respectively formed on both sides of the polarizer.

In the polarizing plate, as external moisture permeates into the inside of the polarizer at high temperature and high humidity, durability of the polarizing plate may be reduced, and scratch resistance of the polarizer may be reduced.

On the other hand, with the recent trend toward thinner display devices, a single-sided polarizing plate having a protective film on one surface of a polarizing plate and an adhesive layer directly formed on the opposite surface without the protective film has been developed in order to reduce the thickness of the polarizing plate. However, in the case of a single-sided polarizing plate in which an adhesive layer is formed directly on a polarizing plate as described above, if a transparent conductive film electrode such as an ITO film is attached to a panel of a display device after treatment, the moisture permeability is high, iodine or the like attached to the polarizing plate is eluted, and the transparent conductive film electrode such as an ITO film is corroded, and in this case, a problem of visible unevenness on the panel is caused.

Korean laid-open patent No. 2010-0018462 discloses a polarizing plate and an optical display device including the same, but there is still a limitation in solving the above problems.

Disclosure of Invention

Technical subject

The polarizing plate according to the embodiment of the present invention includes a protective film including a barrier layer having a specific repeating unit formed on a polarizer, so that moisture permeability toward the polarizer is low, and the polarizing plate can be significantly prevented from being bent under normal temperature, high humidity, or high temperature, high humidity conditions, thereby preventing light leakage from occurring.

In addition, the polarizing plate according to the embodiment of the present invention has a small change in retardation, and can significantly reduce the occurrence of moire fringes.

Means for solving the problems

1. A polarizing plate comprising a polarizing plate and a protective substrate formed on at least one surface of the polarizing plate, wherein the protective substrate comprises a laminate of a protective film and a barrier layer, the barrier layer comprises a repeating unit represented by the following chemical formula 1,

[ chemical formula 1]

(in the formula, R₁And R₂Each independently hydrogen or an alkyl group of 1 to 6 carbon atoms, and n is an integer of 10 to 1,000,000).

2. The polarizing plate according to claim 1, wherein the barrier layer has a storage modulus at 80 ℃ of 500 to 2,000 MPa.

3. The polarizing plate according to claim 1, wherein the protective film has a moisture permeability of 5 to 50g/m measured at a relative humidity of 90% and a temperature of 40 ℃ after 24 hours²Day.

4. The polarizing plate according to claim 1, wherein the barrier layer has a thickness of 0.05nm to 5 μm.

5. The polarizing plate according to claim 1, wherein the protective film is disposed so that the barrier layer faces the polarizing plate, and an adhesive layer is further interposed between the polarizing plate and the barrier layer.

6. A polarizing plate comprising a polarizing plate, and a first protective film and a second protective film formed on both surfaces of the polarizing plate, respectively, wherein the first protective film is disposed on a visible side and has a barrier layer adhered to one surface thereof, the barrier layer comprising a repeating unit represented by the following chemical formula 1,

[ chemical formula 1]

(in the formula, R₁And R₂Each independently hydrogen or an alkyl group of 1 to 6 carbon atoms, and n is an integer of 10 to 1,000,000).

7. The polarizing plate according to claim 6, wherein the barrier layer has a storage modulus at 80 ℃ of 500 to 2,000 MPa.

8. The polarizing plate according to claim 6, further comprising a first adhesive layer interposed between the polarizer and the first protective film, and a second adhesive layer interposed between the polarizer and the second protective film.

9. In the polarizing plate according to claim 8, the barrier layer is disposed so as to face the polarizer, and the first adhesive layer is interposed between the polarizer and the barrier layer.

10. In the polarizing plate according to claim 8, the first adhesive layer is formed from a first adhesive composition containing an acetoacetyl-modified polyvinyl alcohol resin, a glyoxal-based crosslinking agent, and a water-soluble salt of two or more polyvalent metal ions, and the second adhesive layer is formed from a second adhesive composition containing an acetoacetyl-modified polyvinyl alcohol resin and an aziridine crosslinking agent.

11. An image display device comprising the polarizing plate of any one of 1 to 10 above.

Effects of the invention

The polarizing plate according to the embodiment of the present invention includes a barrier layer having a specific repeating unit, so that the moisture permeability to the polarizer is low, and the polarizing plate can be significantly prevented from being bent under normal temperature, high humidity, or high temperature, high humidity conditions, thereby preventing light leakage.

In addition, the polarizing plate according to the embodiment of the present invention has a small change in retardation, and can significantly reduce the occurrence of moire fringes.

Drawings

Fig. 1 is a schematic cross-sectional view for explaining a polarizing plate of an exemplary embodiment.

Fig. 2 is a schematic cross-sectional view for explaining a polarizing plate of an exemplary embodiment.

Detailed Description

An embodiment of the present invention provides a polarizing plate including a polarizing plate and a protective substrate formed on at least one surface of the polarizing plate, wherein the protective substrate includes a laminate of a protective film and a barrier layer, and the barrier layer includes a specific repeating unit. This can significantly prevent the polarizer from being bent under normal temperature, high humidity, or high temperature, high humidity conditions, and thus can effectively prevent light leakage.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the following drawings attached to the present specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the above-described contents of the invention, and therefore the present invention should not be construed as being limited to the matters described in the drawings.

On the other hand, with respect to reference symbols attached to components of respective drawings, the same or similar reference symbols are used for substantially the same components even if they are shown in different drawings. In describing the present invention, detailed descriptions of related known configurations or functions will be omitted if it is considered that the gist of the present invention may be confused.

<Polarizing plate>

Fig. 1 is a schematic cross-sectional view for explaining a polarizing plate of an exemplary embodiment.

Referring to fig. 1, the polarizing plate of the example includes a polarizer 10 and a protective substrate 20.

< polarizing plate >

In one embodiment of the present invention, the polarizing plate 10 is formed by adsorbing and orienting a dichroic dye on a polyvinyl alcohol film.

The polyvinyl alcohol resin constituting the polarizing plate 10 can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acid-based, unsaturated sulfonic acid-based, olefin-based, vinyl ether-based, and acrylamide-based monomers having an ammonium group. The polyvinyl alcohol resin may be a modified resin, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may be used.

The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. Further, the polymerization degree of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

The polyvinyl alcohol resin can be used as an original film of a polarizing plate after being formed into a film. The method for forming the film of the polyvinyl alcohol resin is not particularly limited, and a known method can be used. The film thickness of the polyvinyl alcohol-based raw film is not particularly limited, and may be, for example, 10 to 150 μm.

The polarizing plate 10 is generally manufactured through the following steps: a step of uniaxially stretching the polyvinyl alcohol film; a step of staining the substrate with a dichroic dye to adsorb the dye; a step of treating with an aqueous boric acid solution; and washing and drying.

The step of uniaxially stretching the polyvinyl alcohol film may be performed before dyeing, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, the stretching may be performed before boric acid treatment or may be performed during boric acid treatment. Of course, uniaxial stretching may also be carried out in these multiple steps. In the uniaxial stretching, rolls or hot rolls having different peripheral speeds may be used. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state where the stretching is swollen with a solvent. The draw ratio is usually 3 to 8 times. The step of dyeing the stretched polyvinyl alcohol film with a dichroic dye can be carried out, for example, by immersing the polyvinyl alcohol film in an aqueous solution containing a dichroic dye. Iodine or a dichroic dye is used as the dichroic pigment. The polyvinyl alcohol film is preferably swollen by being immersed in water before dyeing.

When iodine is used as the dichroic dye, a method of immersing the polyvinyl alcohol film in an aqueous dyeing solution containing iodine and potassium iodide to dye the film can be generally used. Generally, the content of iodine in the aqueous solution for dyeing is 0.01 to 1 part by weight relative to 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight relative to 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 ℃ and the dipping time (dyeing time) is usually 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol film in an aqueous dyeing solution containing a water-soluble dichroic organic dye to dye the film can be generally used, and the content of the dichroic organic dye in the aqueous dyeing solution is usually 1 × 10 parts by weight per 100 parts by weight of water^-4To 10 parts by weight, preferably 1 × 10^-3To 1 part by weight. The aqueous solution for dyeing may further contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous solution for dyeing is usually 20 to 80 ℃ and the dipping time (dyeing time) is usually 10 to 1,800 seconds.

The step of subjecting the dyed polyvinyl alcohol film to a boric acid treatment can be performed by immersing the film in an aqueous solution containing boric acid. Generally, the content of boric acid in the aqueous solution containing boric acid is 2 to 15 parts by weight, preferably 5 to 12 parts by weight, relative to 100 parts by weight of water. In the case of using iodine as the dichroic pigment, the boric acid-containing aqueous solution preferably contains potassium iodide in an amount of usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, relative to 100 parts by weight of water. The temperature of the aqueous solution containing boric acid is usually 50 ℃ or more, preferably 50 to 85 ℃, more preferably 60 to 80 ℃, and the immersion time is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. After the treatment with boric acid, the polyvinyl alcohol film is usually washed with water and dried. The water washing treatment can be performed by immersing the polyvinyl alcohol film after the boric acid treatment in water. The temperature of the water for the water washing treatment is usually 5 to 40 ℃ and the immersion time is usually 1 to 120 seconds. The polarizing plate can be obtained by washing with water and then drying. The drying treatment is generally carried out using a hot air dryer or a far infrared heater. The drying treatment temperature is usually 30 to 100 ℃, preferably 50 to 80 ℃, and the drying time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

The details of the polarizing plate 10 of the embodiment of the present invention can be applied to korean laid-open patent No. 10-2016-.

< protective substrate >

The protective substrate 20 is formed on at least one surface of the polarizing plate 10, and may include a laminate including a protective film 21 and a barrier layer 22, as shown in fig. 1, for example.

Protective film

In some examples of the present invention, the protective film 21 may be a film excellent in transparency, mechanical strength, thermal stability, water resistance, isotropy, and the like, and specific examples thereof include polyester-based films such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; cellulose films such as diacetylcellulose and triacetylcellulose; acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; styrene-based films such as polystyrene and acrylonitrile-styrene copolymer; a polycarbonate-based film; polyolefin-based films such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; a vinyl chloride film; amide films such as nylon and aromatic polyamide; an imide-based film; a polyethersulfone membrane; a sulfone-based membrane; a polyether ether ketone film; a polyphenylene sulfide-based film; a vinyl alcohol-based film; a vinylidene chloride film; a polyoxymethylene film; epoxy-based films, and the like. Preferably, a polyester film, a cellulose film, an acrylic film, or a polyolefin film can be used.

In some embodiments, the thickness of the protective film 21 is generally 20 to 500 μm.

The protective film 21 can be produced by a method generally used in the art, and is preferably produced by extrusion molding by a melt extrusion method such as T-die method or inflation, casting by a melt kneading method, or rolling. Extrusion molding does not require a step of drying and scattering an organic solvent in an adhesive used in processing, as in the dry (dry) lamination method, and is excellent in terms of productivity. Specifically, there is a method in which a (meth) acrylate resin composition as a raw material is fed to an extruder connected to a T-die, melt-kneaded and extruded, and then water-cooled and drawn to form a film. The screw type of the extruder may be uniaxial or biaxial, and additives such as a plasticizer and an antioxidant may be added. The extrusion molding temperature may be appropriately adjusted, and is preferably 80 to 180 ℃ higher, more preferably 100 to 150 ℃ higher than the glass transition temperature (Tg) of the resin that becomes the raw material of the protective film. If the extrusion molding temperature is too low, the flowability of the resin is insufficient and the moldability is poor, and if the temperature is too high, the viscosity of the resin becomes low and there is a possibility that the production stability is lowered such as the thickness of the finally molded film becomes uneven.

A surface treatment layer such as a hard coat layer, an antireflection layer, an antiglare layer, and an antistatic layer may be further laminated on the protective film 10 as necessary.

The detailed contents of the protective film 10 can be applied to korean laid-open patent No. 10-2016-.

Barrier layer

The barrier layer 22 may be provided to protect the polarizing plate 10 and to prevent external moisture from penetrating into the polarizing plate 10, thereby improving durability under normal temperature/high humidity or high temperature/high humidity conditions.