KR20100102290A - Surface protective film and polarizing plate comprising the same - Google Patents

Abstract

PURPOSE: A surface protection film for a polarizing plate and a polarizing plate thereof are provided to remove static electricity. CONSTITUTION: A base film(10) sequentially forms an anti-electrification layer(13) and an uneven layer(12) on a transparent film(11). An adhesive layer(20) includes an adhesive compound which includes an adhesive resin. A release film(30) protects the adhesive layer.

Description

Surface protection film for polarizing plate and polarizing plate equipped with it {SURFACE PROTECTIVE FILM AND POLARIZING PLATE COMPRISING THE SAME}

The present invention is to improve the handleability of the polarizing plate in the bonding process of the liquid crystal cell and the polarizing plate to prevent the tupole fail phenomenon and at the same time to solve the problem of static electricity, and a polarizing plate with a polarizing plate provided with the surface protective film It is about.

Liquid crystal display devices (LCDs) are laminated with expensive optical films such as polarizing plates, which may be damaged or contaminated during assembly, bonding, or transportation and distribution with liquid crystal cells. Since minute damages and defects of the optical film cause a defect of the liquid crystal display device, a surface protection film is used to protect the polarizing plate by being attached to the surface of the polarizing plate to prevent this.

In this way, the polarizing plate on which the surface protective film is laminated is bonded to the liquid crystal cell to manufacture a panel. In this case, the polarizing plates are lifted one by one so as to be suitable for the bonding process. However, the stacked polarizers are temporarily attached to each other by two or more polarizers due to their own weight pressure, and thus, a plurality of attached polarizers are lifted and put into the bonding process instead of one polarizer. Hereinafter, the "tupolfail phenomenon" will occur. This phenomenon should not occur in the process because it causes problems such as product defects, an increase in manufacturing costs due to loss of raw materials, and a decrease in process efficiency.

In addition, after fabricating the panel by bonding the polarizing plate to the liquid crystal cell, the surface protective film laminated on the polarizing plate is peeled off in the assembling process. Generally, since the surface protective film and the polarizing plate are made of a plastic material, static electricity is generated. . The static electricity generated in this way adsorbs foreign matter to the optical member to contaminate the surface and cause staining due to the distortion of the liquid crystal alignment, and there is a problem of damaging the thin film transistor line.

According to the present invention, the stacked polarizing plates are separated from each other without being attached to each other to facilitate handling, and the process efficiency can be improved by preventing the phenomenon of polarization during the bonding process between the polarizing plate and the liquid crystal cell, and at the same time, the problem of generating static electricity can be solved. An object of the present invention is to provide a surface protective film for a polarizing plate.

In addition, another object of the present invention is to provide a polarizing plate in which the surface protective film for polarizing plate is laminated.

In order to achieve the above object, the present invention provides a surface protective film for a polarizing plate formed with an uneven layer on the transparent film.

In addition, the present invention provides a polarizing plate in which the surface protective film for polarizing plate is laminated.

The surface protective film for polarizing plates according to the present invention improves the handleability of the polarizing plate by suppressing adhesion of the stacked polarizing plates with excellent detachability and slipability without degrading optical properties such as transparency, total light transmittance, and haze of the polarizing plate. In addition, the efficiency of the process can be improved by preventing the two-pole fail phenomenon in which a plurality of polarizing plates are attached to each other in the conventional bonding process of the polarizing plate and the liquid crystal cell, and at the same time, the antistatic property can be solved to solve the problem of static electricity generation. have.

The present invention is to improve the handleability of the polarizing plate in the bonding process of the liquid crystal cell and the polarizing plate to prevent the tupole fail phenomenon and at the same time to solve the problem of static electricity, and a polarizing plate with a polarizing plate provided with the surface protective film It is about.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Surface protective film for polarizing plate of the present invention is characterized in that the uneven layer is formed on the transparent film. More specifically, the surface protective film for a polarizing plate of the present invention is that the base film, the pressure-sensitive adhesive layer and the release film is laminated in order, in particular, the base film is characterized in that the uneven layer is formed on the transparent film.

As shown in FIG. 1, the surface protection film according to the exemplary embodiment of the present invention is a film in which the uneven layer 12 is formed on the transparent film 11 as the base film 10 ′.

The transparent film 11 is a substrate for forming the uneven layer, and the kind thereof is not particularly limited as long as it is a transparent film made of a thermoplastic resin. For example, Polyester film, such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate; Polycarbonate film; Polyether sulfone-based film; Polyolefin-based films such as polyethylene, polypropylene, cyclo- or norbornene-structured polyolefins, ethylene propylene copolymers, and the like can be used, among them, polyethylene terephthalate film having excellent transparency and heat resistance, polyethylene-2,6-naphthalate Films or polycarbonate films and the like are preferred.

The transparent film may be prepared by a conventional method. For example, in the case of polyethylene terephthalate (PET) film, the PET resin is melt-extruded using a conventional method and then treated at an appropriate temperature to form a sheet, and the formed sheet is longitudinally 3-6 at 70-140 ° C. After fold stretching, stretching in the transverse direction 3-5 times and then heat-setting at 170-240 ℃ can be prepared. At this time, in order to improve the adhesiveness with the pressure-sensitive adhesive layer 20 may be subjected to surface treatment or primer treatment on one or both sides of the transparent film.

It is preferable that the thickness of the said transparent film is 10-80 micrometers, More preferably, it is 15-40 micrometers. If the thickness is less than 10 μm, the processability is lowered due to the influence of elasticity and tensile strength of the film. If the thickness is more than 80 μm, the economy is inferior.

The uneven layer 12 is a layer for preventing the stacked polarizing plates from adhering to each other by their own weight pressure by forming a bend on the surface of the final surface protection film, and among the organic beads, inorganic beads and organic-inorganic composite beads It is formed from a composition comprising at least one bead selected.

Organic beads include acrylics such as polymethyl methacrylate (PMMA); Styrenes such as polystyrene; Silicone based such as metasilicon; Polyacryl-styrene systems such as polymethylmethacrylate-polystyrene; Melamine type; And beads made of vinyl-based resin can be used. As inorganic beads, silica, potassium carbonate, aluminum hydroxide, magnesium hydroxide and titanium dioxide beads can be used. In addition, as the organic-inorganic composite beads, polymethyl methacrylate beads having a modified surface of silica can be used.

The average diameter of the beads is preferably 5 μm or less, preferably 0.1 to 5 μm, and two or more kinds of beads having different sizes and types may be mixed and used within this average diameter range. In addition, the beads preferably have a uniform average diameter and monodispersity.

In addition to the beads, the composition for forming the uneven layer 12 includes a binder resin that enables the formation of the uneven layer through a curing reaction and a curing agent as necessary.

The binder resin is not particularly limited as long as it is a water-soluble or solvent-type binder. For example, a binder resin containing one or more functional groups such as acrylic, urethane, silane, and the like may be used. Or it can use in combination of 2 or more type.

In addition, the type of the curing agent is not particularly limited, but for example, for reinforcing the physical properties of the formed uneven layer, an epoxy curing agent and a catalyst, or a weak organic acid curing agent such as naphthalene sulfonic acid may be used. You can choose the type according to.

The binder resin, the bead, and the curing agent may be mixed with a solvent, and the solvent may be an organic solvent such as an alcohol solvent such as methanol, ethanol, isopropanol or butanol, a ketone solvent such as acetone, or a benzene solvent such as toluene or xylene. A solvent or water can be used, and these can be used individually or in combination of 2 or more types.

Thus, the composition containing the binder resin, the bead and the curing agent on the transparent film 11 using a conventional method, for example, air knife, gravure, reverse roll, kiss roll, spray, blade or bar coater, etc. It can form by hardening | curing after apply | coating by coating.

The size of the irregularities formed in the uneven layer 12 may be adjusted according to the size of the beads used, preferably about 0.01 to 10㎛, more preferably 0.1 to 5㎛.

In the present invention, an antistatic layer may be further formed on at least one side of the uneven layer.

As shown in FIG. 2, another surface protection film according to another embodiment of the present invention is a film in which the uneven layer 12 and the antistatic layer 13 are sequentially formed on the transparent film 11 as the base film 10. This is laminated.

The antistatic layer 13 is a layer made of a composition containing a conductive material.

The conductive material is not particularly limited as long as the material exhibits antistatic performance. For example, a conductive polymer, a metal oxide, a quaternary ammonium salt, or the like can be used.

The conductive polymer may be polythiophene, polyaniline, polypyrrole, such as poly3,4-ethylenedioxythiophene (PEDOT, manufactured by Bayer), and the like, and the metal oxide may be indium-doped tin oxide (ITO) or antimony. Tin oxide compounds such as doped tin oxide (ATO), zinc oxide compounds, antimony oxide compounds, indium oxide compounds and the like can be used. In addition, as said quaternary ammonium salt, poly (acrylamide-co-diallyldimethylammonium) chloride solution (made by Sigma-Aldrich), 1-butyl-3- methyl imidazolium hexafluoro phosphate, and tetrabutyl methyl ammonium bis (Trifluoromethanesulfonyl) imide etc. can be used, These can be used individually or in combination of 2 or more types. Among them, it is preferable to use a conductive polymer or metal oxide having excellent transparency, and poly3,4-ethylenedioxythiophene, which is a derivative of polythiophene, is more preferable because of its excellent electrical conductivity, high transparency and good thermal stability. .

The conductive material is preferably included in an amount of 0.01 to 20% by weight, more preferably 0.1 to 10% by weight relative to the total content (solid content basis) of the composition for forming the antistatic layer 13. If the content is less than 0.01% by weight, the antistatic performance effect is insignificant, and if it exceeds 20% by weight, the dispersibility is lowered, resulting in poor stability of the composition, thereby making it difficult to obtain a uniform coating film.

A binder resin is included in the composition for forming the antistatic layer 13 in addition to the conductive material.

As the binder resin, polyurethane resin, polyester resin, acrylic resin, polyether resin, cellulose resin, polyvinyl alcohol resin, epoxy resin, polyvinylpyrrolidone, polystyrene resin, polyethylene glycol, penta An organic binder such as erythritol or an inorganic binder such as silicate may be used, and these may be used alone or in combination of two or more thereof. Among them, polyurethane resins, polyester resins and acrylic resins are particularly preferable.

The conductive material and the binder resin may be mixed with a solvent, and the solvent may be an alcohol solvent such as methanol, ethanol, isopropanol or butanol, a ketone solvent such as acetone, or an organic solvent such as a benzene solvent such as toluene or xylene. Or water may be used, and these may be used alone or in combination of two or more thereof.

In addition to the above components, additives such as nonionic surfactants, leveling agents, wetting agents, and slip agents may be further used for the formation of the antistatic layer.

The method of forming the antistatic layer 13 is formed by applying a composition containing a binder resin, a bead, and a curing agent on the uneven layer 12 using a conventional coating method as in the formation of the uneven layer, followed by drying. can do.

The thickness of the antistatic layer 13 is not particularly limited.

In the present invention, the uneven layer 12 and the antistatic layer 13 may be integral layers instead of respective layers. As shown in FIG. 3, the surface protection film according to another embodiment of the present invention is an antistatic concave-convex layer 14 having a function of an uneven layer and an antistatic layer on the transparent film 11 as the base film 10. This formed film is laminated.

The antistatic concave-convex layer 14 can be formed by adding a conductive material to the composition used in forming the concave-convex layer 12, and then applying and curing the composition in the same manner.

The antistatic layer 13 or the antistatic uneven layer 14 preferably has a surface specific resistance of 10 ⁵ to 10 ¹² mA / □ at 500 V, more preferably 10 ⁵ to 10 ¹⁰ mA / □, most preferably 10 ⁷ to 10 ⁹ μs / sq.

In the present invention, the order of forming the uneven layer 12 and the antistatic layer 13 on the transparent film 11 is not particularly limited. That is, the uneven layer 12 and the antistatic layer 13 may be formed on the transparent film 11 in the order, and on the contrary, the antistatic layer 13 and the uneven layer 12 may be formed on the transparent film 11. It may be formed. Therefore, as shown in Figure 4, the surface protection film according to another embodiment of the present invention is formed as the base film 10, the antistatic layer 13 and the uneven layer 12 in order on the transparent film 11 The film is laminated.

In the present invention, the antistatic layer 13 may be further formed on the other side of the base film on which the uneven layer 12 is not formed. Therefore, as shown in FIG. 5, the surface protection film according to another embodiment of the present invention has an antistatic layer 13 and an uneven layer 12 on one side of the transparent film 11 as the base film 10. It is formed, and the film in which the antistatic layer 13 is formed on the other side of the transparent film 11 is laminated | stacked.

The pressure-sensitive adhesive layer 20 is a layer made of a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive resin commonly used in the art.

In addition, the pressure-sensitive adhesive layer 20 may be an antistatic pressure-sensitive adhesive layer made of an antistatic pressure-sensitive adhesive composition containing the same conductive material as used in the formation of the antistatic layer 13.

The method of laminating the pressure-sensitive adhesive layer 20 on the base film 10 is not particularly limited as long as it is a method commonly used in the art. For example, the pressure-sensitive adhesive composition on the base film 10 is directly applied in a suitable development method using a flow casting method and a coating method such as air knife, gravure, reverse roll, kiss roll, spray, blade or bar coater, and the like. It can be dried and laminated. In addition, after the pressure-sensitive adhesive layer is formed on the release film subjected to the silicone release treatment by the same coating method as described above, the pressure-sensitive adhesive sheet may be manufactured, and then it may be laminated on the base film using a roll pressing device. At this time, when an ultraviolet curable compound is contained in an adhesive composition, it is preferable to irradiate an ultraviolet-ray.

The thickness of the pressure-sensitive adhesive layer 20 is preferably 5 to 50㎛, preferably 5 to 25㎛.

The release film 30 is a film for protecting the pressure-sensitive adhesive layer, and if the film is commonly used in the art, its kind is not particularly limited. Specific examples include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethylacrylic Polyolefin-based films such as a late copolymer and an ethylene-vinyl alcohol copolymer; Polyester-based films such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polyacrylate film; Polystyrene film; Polyamide films such as nylon 6 and partially aromatic polyamides; Polyvinyl chloride film; Polyvinylidene chloride film; Or polycarbonate film etc. can be used. In addition, these can be used by appropriately releasing a release agent such as silicone-based, fluorine-based, silica powder or the like.

As described above, the surface protective film in which the base film 10, the pressure-sensitive adhesive layer 20, and the release film 30 are sequentially stacked has a haze value of 5% or less, and a total light transmittance of 80 to 99%. Do. If the haze value is more than 5% or the total light transmittance is less than 80%, it is difficult to detect defects in the polarizing plate or the optical film during the product defect inspection step when used for the substrate for the liquid crystal display device or the protective film. Haha.

In addition, the surface protective film preferably has a static friction coefficient (µs) of 0.32 or less, more preferably 0.30 or less, and most preferably 0.27 or less on the surface where the uneven layer of the base film is formed. In the above range, the tupolefail phenomenon can be effectively prevented.

The surface protection film of the present invention protects the surface of various optical members, for example, members made of plastic materials such as polarizing plates, retardation plates, optical compensation films, reflective sheets, brightness enhancement films, etc. used in liquid crystal display devices, and at the same time It can be used to solve the problem of occurrence.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

Example 1

A composition of 0.5 g of acrylic monodisperse beads (SBX-4, manufactured by Sekisui), 9.5 g of acrylic binder resin, and 40 g of toluene having an average diameter of 3 μm was applied to one side of a polyethylene terephthalate (PET, 38 μm) film. It was applied using a coater and dried at 80 ° C. to form an uneven layer.

3,4-polyethylenedioxythiophene water dispersion (solid content: 10% by weight) solution (Baytron P, Bayer) 4g, polyurethane binder 10g, ethylene glycol 1g, olefin slip agent (lakewax29, lakelane) 0.5 g and 34.5 g of water were mixed to prepare an antistatic coating solution to form a water dispersion mixture. The prepared coating solution was applied on the formed uneven layer by using a bar coater and dried at 80 ° C. for 2 minutes to prepare a PET base film having a total thickness of 41 μm.

Surface Protection Film Preparation: A surface protection film was prepared by laminating a conventional acrylic pressure-sensitive adhesive layer and a PET-based release film on the other side of the prepared uneven layer and the antistatic layer of the PET base film.

Example 2

3,4-polyethylenedioxythiophene water dispersion (solid content: 10% by weight) solution (Baytron P, Bayer Co.) 4g, polyurethane binder 10g, ethylene glycol 1g, acrylic monodisperse beads (MX having an average diameter of 4㎛) Series, manufactured by soken) 0.05g, olefinic slip agent (lakewax29, Lakelane Co., Ltd.) 0.5g and 34.45g of water was mixed to prepare a coating solution for forming an antistatic concave-convex layer to form a water dispersion. The prepared composition was coated on a PET film (38 μm) using a bar coater, and then dried at 80 ° C. for 2 minutes to prepare a PET base film having a total thickness of 42 μm.

A surface protection film was prepared by laminating a conventional acrylic pressure-sensitive adhesive layer and a PET-based release film on the other side of the prepared uneven layer and the antistatic layer of the PET base film.

Comparative Example 1

The same method as in Example 1 was carried out except that only the antistatic layer was formed without forming the uneven layer.

Test Example

The physical properties of the surface protective films prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 1 below.

(1) Surface resistivity (Ω / □)

-Measuring instrument: surface resistance measuring instrument (MCP-HT450 / MITSUBISHI CHEMICAL)

Probe (URS, UR100), Probe Checker (for URS, UR 100)

-Measurement method: Three points on the surface of the antistatic layer or the antistatic concave-convex layer were measured 10 times, respectively, and expressed as the average value.

(2) haze and total light transmittance

The haze value and total light transmittance of the surface protection film were measured based on JISK-7136 using the haze measuring device (HM-150, the Murakami company make).

(3) Static friction coefficient (μs)

The surface on which the uneven | corrugated layer was formed was used the friction coefficient measuring device (Pull slip tester, Corinth Tech Co., Ltd.), and the static friction coefficient was measured based on ASTM-1894.

(4) Tupolefail Evaluation

The prepared surface protection film was laminated on a conventional polarizing plate and then loaded. Repeat the test of lifting the loaded polarizing plate using a vacuum lifter (Easy Lifter, manufactured by Seika Tech Co., Ltd.) 100 times and visually observing whether two or more polarizing plates are attached and lifted, that is, a tupole fail phenomenon. And evaluated according to the following criteria.

(Circle): There is no tupole fail.

X: There is a tupole fail phenomenon.

division Surface resistivity
(Ω / □) Hayes
(%) Total light transmittance (%) Static friction coefficient Tupole Fail Example 1 10 ⁷ 3.3 87.7 0.24 ○ Example 2 10 ⁷ 3.9 89.3 0.27 ○ Comparative Example 1 10 ⁷ 1.9 91.5 0.34 ×

As shown in Table 1, according to the present invention, the surface protective film of Examples 1 and 2 including the base film having the uneven layer and the antistatic layer or the antistatic uneven layer formed on the transparent film is not provided with the uneven layer. Compared with the surface protection film of Comparative Example 1, the stacked polarizers can be prevented from adhering to each other without degrading optical properties, thereby solving the problem of electrostatic as well as the fold-pole failure in the bonding process between the polarizer and the liquid crystal cell. I could confirm it.

1 to 5 are cross-sectional views of the surface protection film according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10 ', 10: base film 11: transparent film

12: uneven layer 13: antistatic layer

14: antistatic uneven layer 20: pressure-sensitive adhesive layer

30: release film

Claims (9)

Surface protective film for a polarizing plate formed with an uneven layer on the transparent film. The surface protective film for polarizing plates of Claim 1 whose static friction coefficient (microsecond) in the uneven | corrugated layer surface is 0.32 or less. The surface protection film for polarizing plates of Claim 2 which further contains an antistatic layer. The surface protective film for polarizing plates of Claim 2 whose uneven | corrugated layer is an antistatic uneven | corrugated layer. Claim 3 or claim 4, wherein a surface resistivity of 10 ⁵ to 10 ¹² Ω / □ surface of the polarizing plate protective film for at 500V. The surface protective film for polarizing plates of claim 1, wherein the uneven layer is formed on a transparent film that is not bonded to the pressure-sensitive adhesive layer. The surface protective film of claim 1, wherein the surface protective film is formed by laminating a transparent film, an adhesive layer, and a release film in order. The method of claim 1, wherein the uneven layer is an organic bead of acrylic, styrene, silicone, melamine, polyacryl-styrene and vinyl resin; Silica, potassium carbonate, aluminum hydroxide, magnesium hydroxide and titanium dioxide inorganic beads; And at least one bead selected from organic-inorganic composite beads modified from the surface of silica. The polarizing plate in which the surface protection film for polarizing plates of any one of Claims 1-4 was laminated | stacked.

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