KR20140074492A - Acrylate film and polarising plate using the same - Google Patents

Abstract

The present invention relates to an acrylate-based film and a polarizing plate using the same and, more specifically, to an acrylate-based film capable of keeping ultraviolet blocking performance even after aging and being made into a film because the acrylate-based film is copolymerized while containing ultraviolet absorbing copolymeric monomers that have a specific ultraviolet absorbing group and a copolymerization functional group, thereby being useful as a protective film for a polarizer, and to a polarizing plate using the acrylate-based film.

Description

TECHNICAL FIELD [0001] The present invention relates to a polarizing plate,

The present invention relates to an acrylate film containing an ultraviolet absorbing acrylic monomer and a polarizing plate using the acrylate film.

The liquid crystal display comprises a liquid crystal cell in which a transparent electrode, a liquid crystal layer, and a color filter are sandwiched between glass plates, and a polarizing plate laminated on both surfaces of the liquid crystal cell.

The polarizing plate is laminated with a polarizer and a polarizing plate protective film on both sides thereof. A cellulose-based protective film or a cycloolefin-based protective film is used as the polarizer protective film to be bonded to the pressure-sensitive adhesive, and a cellulose-based protective film is generally used on the opposite side.

At this time, the cellulose-based protective film which is not bonded to the pressure-sensitive adhesive essentially contains a UV-blocking agent for suppressing the liquid crystal deformation due to ultraviolet rays introduced from external light or backlight.

On the other hand, liquid crystal display devices are being transported through hot and humid areas such as tropical regions, near the sea, near the equator, or the like, and the demand for durability such as heat resistance and moisture resistance is increasing.

A configuration in which a low moisture permeable protective film such as a cycloolefin-based or acrylate-based film is used as a polarizer protective film is proposed.

However, low moisture-permeable protective films such as cycloolefin-based or acrylate-based films are less compatible with ultraviolet screening agents than cellulose-based protective films, and bleed-out phenomenon occurs. Therefore, there is a problem that physical properties are unstable due to changes in film over time.

In addition, the cycloolefin-based or acrylate-based protective film produced by the melt extrusion method has a problem that the ultraviolet screening agent is volatilized or decomposed at the production stage.

The present invention relates to an ultraviolet light absorbing resin composition which is copolymerized with an ultraviolet absorbing copolymerizable monomer having both an ultraviolet absorbing group and a copolymerizing functional group in a molecule so that the ultraviolet barrier property is not lowered with the elapse of time, And an object of the present invention is to provide an acrylate-based film capable of suppressing occurrence of decomposition and the like.

It is another object of the present invention to provide a polarizing plate in which the acrylate film is laminated with a polarizer protective film.

In order to accomplish the above object, the present invention provides a process for producing a 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 membered ring selected from the group consisting of oxiphenone, benzotriazole, salicylate, benzophenone, cyanoacrylate, triazole, triazine, Ultraviolet absorbing groups of at least two species; And an ultraviolet absorbing copolymerizable monomer having at least one copolymerizable functional group selected from the group consisting of a (meth) acrylic group, a vinyl group, an allyl group and a styryl group.

Preferably, the ultraviolet absorbing group of the ultraviolet absorbing copolymerizable monomer may be at least one selected from the group consisting of oxyphenone, benzotriazole and triazine.

(R₁은 H 또는 CH₃),

및

로 이루어진 군에서 선택된 1종 이상일 수 있다.More preferably, the ultraviolet absorbing copolymerizable monomer is

(R ₁ is H or CH ₃ ),

And

And the like.

The acrylate-based film may include: 1) methyl methacrylate; 2) polymerizable monomers; And 3) at least one ultraviolet absorbing group selected from the group consisting of oxiphenone, benzotriazole, salicylic ester, benzophenone, cyanoacrylate, triazole, triazine, nickel complex salt and inorganic powder, and (Meth) acrylic group, a vinyl group, an allyl group, and a styryl group, and may be one copolymerized with an ultraviolet absorbing copolymerizable monomer having at least one copolymerizable functional group.

The acrylate-based film may be copolymerized with 1) methyl methacrylate in an amount of 45 to 98.9% by weight, 2) 1 to 50% by weight of a polymerizable monomer, and 3) 0.1 to 5% by weight of an ultraviolet absorbing copolymerizable monomer have.

Further, the present invention provides a polarizing plate, wherein the acrylate-based film according to any one of claims 1 to 5 is laminated on at least one surface of the polarizer.

Since the ultraviolet absorbing copolymerizable monomer is copolymerized with the acrylate resin, the ultraviolet barrier property of the acrylate film according to the present invention does not deteriorate with the elapse of time, and the volatilization and decomposition of the ultraviolet blocking agent And can be advantageously used as a protective film of a polarizer.

In addition, the polarizing plate according to the present invention can be usefully used when a liquid crystal display device including a polarizing plate is transported through a high temperature and high humidity region such as a tropical region, a region adjacent to the sea, and an equator.

In addition, the polarizing plate according to the present invention can be effectively used even when a backlight having a large amount of heat is used for better sharpness, or when the distance between the polarizing plate and the backlight is reduced while the liquid crystal display is thinned.

The present invention relates to an acrylate film containing an ultraviolet absorbing acrylic monomer and a polarizing plate using the acrylate film.

Hereinafter, the present invention will be described in detail.

The acrylate-based film of the present invention may contain at least one selected from the group consisting of oxyphenone, benzotriazole, salicylic ester, benzophenone, cyanoacrylate, triazole, triazine, nickel complex salt and inorganic powder Ultraviolet absorptive group, and ultraviolet absorbing copolymerizable monomer having at least one copolymerizable functional group selected from the group consisting of (meth) acrylic group, vinyl group, allyl group and styryl group.

(R₁은 H 또는 CH₃),

및

로 이루어진 군에서 선택된 1종 이상인 것이 보다 바람직하다.Preferably, the ultraviolet absorbing group of the ultraviolet absorbing copolymerizable monomer is at least one selected from the group consisting of an oxyphenone series, a benzotriazole series, and a triazine series. Considering the compatibility with the monomer to be copolymerized, the ease of copolymerization and the ease of production of the raw material, the ultraviolet absorbing copolymerizable monomer

(R ₁ is H or CH ₃ ),

And

And more preferably at least one selected from the group consisting of

The ultraviolet absorbing copolymerizable monomer contained in the acrylate film of the present invention has an ultraviolet absorptive functional group selected in consideration of compatibility, copolymerization and ease of raw material production.

In addition, the ultraviolet absorbing copolymerizable monomer can prevent the conventional ultraviolet blocking agent from being bleed out by the copolymerizing functional group, so that stability of physical properties can be ensured even with time.

These acrylic monomers may be synthesized or commercially available products. As a synthesizing method, European Patent No. 2065362, Journal of Photochemistry 2011. 26, Macromolecules 2004. 882, US Patent No. 2011-196169, US Patent No. 5714134, US Patent No. 5672704, and the like can be used.

The acrylate-based film of the present invention is a film containing a (meth) acrylate resin, and contains 50 parts by weight or more of the resin for the entire resin composition. A polymethyl methacrylate (PMMA) film is preferable in consideration of ease of handling and price competitiveness.

The acrylate-based film may include: 1) methyl methacrylate; 2) polymerizable monomers; And 3) at least one ultraviolet absorbing group selected from the group consisting of oxiphenone, benzotriazole, salicylic ester, benzophenone, cyanoacrylate, triazole, triazine, nickel complex salt and inorganic powder, and Containing copolymerizable monomer having at least one copolymerizable functional group selected from the group consisting of a (meth) acrylic group, a vinyl group, an allyl group and a styryl group.

The polymerizable monomer may be an alkyl methacrylate having 2 to 18 carbon atoms in the alkyl group, an alkyl acrylate having 1 to 18 carbon atoms in the alkyl group, an alpha, beta -unsaturated acid such as acrylic acid or methacrylic acid; Unsaturated carboxylic acid containing unsaturated groups such as maleic acid, fumaric acid and itaconic acid; Aromatic vinyl compounds such as styrene and? -Methylstyrene; ?,? - unsaturated nitriles such as acrylonitrile and methacrylonitrile; Maleic anhydride, maleimide, N-substituted maleimide, glutaric acid anhydride, and acrylamide derivatives such as acryloylmorpholine. These may be used alone or in combination of two or more kinds of monomers.

Of these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, and 2-ethylhexyl acrylate are preferable in consideration of thermal decomposition resistance and fluidity of the copolymer, Methyl acrylate and n-butyl acrylate are preferred.

The acrylate-based film may contain 1) 45 to 98.9% by weight of methyl methacrylate, 2) 1 to 50% by weight of a polymerizable monomer, and 3) 0.1 to 5% by weight of an ultraviolet absorbing copolymerizable monomer.

If the content of methyl methacrylate is less than 45% by weight, the hardness of the film is insufficient, and when it is applied as a protective film of a polarizer, the polarizing plate may have insufficient resistance to shrinkage stress upon shrinking the polarizer, If the content is more than 10% by weight, defects may occur during handling due to lack of flexibility. When the content of the polymerizable monomer is less than 1% by weight, flexibility may be insufficient. When the content of the polymerizable monomer is more than 50% by weight, the hardness may be insufficient and durability may be deteriorated. If the content of the ultraviolet absorbing copolymerizable monomer is less than 0.1% by weight, the ultraviolet blocking property may be insufficient. If the content is more than 5% by weight, the visible light transmittance may be lowered.

The (meth) acrylate resin used in the acrylate film of the present invention preferably has a weight average molecular weight (Mw) in the range of 110,000 to 1,000,000, preferably 140,000 to 600,000, and more preferably 200,000 to 400,000. When the weight average molecular weight (Mw) is out of the above-mentioned range, the process stability in production of the film may be lowered and the durability after the formation of the polarizing plate may be lowered.

The (meth) acrylate resin of the present invention can be produced by a method generally used in the art, specifically, suspension polymerization, emulsion polymerization, bulk polymerization or solution polymerization.

At this time, the polymerization initiator may be a peroxide system, an azo system, an oxidation / reduction system, or the like. The polymerization temperature varies depending on the polymerization method. Suspension or emulsion polymerization can be carried out at 30 to 100 ° C, and bulk or solution polymerization can be carried out at 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization may also be carried out using alkylmercaptan or the like as a chain transfer agent.

In addition, the (meth) acrylate resin of the present invention may contain a multi-layered acrylic particulate composite.

The multi-layered acrylic granular composite may be preferably used as follows. (a) a copolymer obtained by polymerizing a mixture of monomers comprising 80 to 98.9% by weight of methyl methacrylate, 1 to 20% by weight of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and 0.01 to 0.3% by weight of a multifunctional graft (B) from 75 to 98.5% by weight of an alkyl acrylate having from 4 to 8 carbon atoms in the alkyl group, from 0.01 to 5% by weight of a polyfunctional crosslinking agent and from 0.5 to 5% by weight of a polyfunctional grafting agent in the presence of the innermost hard layer polymer (C) 80 to 99% by weight of methyl methacrylate and 1 to 8 carbon atoms in the alkyl group in the presence of the polymer comprising the innermost hard layer and the crosslinked soft layer, Layer structure composed of an outermost hard layer polymer obtained by polymerizing a mixture of monomers consisting of 1 to 20% by weight of alkyl acrylate .

The present invention is characterized by a polarizing plate on which the acrylate-based protective film is laminated on at least one surface of a polarizer. The acrylate-based protective film serves as a polarizer protective film.

The acrylate-based protective film may be subjected to a surface treatment to facilitate bonding with the polarizer. For example, a dry treatment such as a primer treatment, a plasma treatment or a corona treatment, a chemical treatment such as an alkali treatment (saponification treatment) , A coating treatment for forming an easy adhesive layer, and the like.

The bonding method and the adhesive are not particularly limited as they are conventional in the art. After bonding the polarizer and the protective film, a drying treatment may be performed

A surface treatment layer such as a hard coating layer, an antireflection layer, an antiglare layer, and an antistatic layer may be further laminated on the other side of the polarizer to which the polarizer protective film is bonded on one side. Further, an optical functional film may be further laminated by a pressure-sensitive adhesive layer. Examples of the optically functional film include an optical compensation film in which a liquid crystal compound or a polymer compound thereof is oriented on the surface of a base material, an optical compensation film that transmits polarized light of any kind and reflects polarized light of a property opposite to that, A retardation film including a cyclic polyolefin resin, an antireflection functional film having a concavo-convex shape on its surface, an additional film having a surface antireflection treatment, a reflection film having a reflective function on the surface, And a transflective film having both a reflecting function and a transmitting function.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  1 to 6 and Comparative Example  1 to 4

The mixture was charged into a 1 L reactor equipped with a cooling device to regulate the temperature of the nitrogen gas and to facilitate the regeneration of the temperature, and then 100 parts by weight of ethyl acetate was added as a solvent. Nitrogen gas was then purged for 1 hour to remove oxygen and then maintained at 70 ° C. After the mixture was homogenized, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 6 hours to prepare an acrylate resin.

The acrylate resin obtained above was coated on a polyethylene terephthalate (PET) laminated with a silicone release film to a dry thickness of 80 占 퐉, dried at 100 占 폚 for 5 minutes, and then the release film was peeled off to obtain polymethyl methacrylate (PMMA) film.

division
(Parts by weight) MMA BMA Ultraviolet absorptivity
Acrylic monomer Sunscreen A-1 A-2 A-3 B-1 B-2 B-3 Example 1 89 10 One - - - - - Example 2 89 10 - One - - - - Example 3 89 10 - - One - - - Example 4 88.5 10 - - 0.5 - - - Example 5 88 10 - - 2 - - - Example 6 86 10 - - 4 - - - Comparative Example 1 90 10 - - - - - - Comparative Example 2 90 10 - - - One - - Comparative Example 3 90 10 - - - - One - Comparative Example 4 90 10 - - - - - One

(R₁=H)
A-2:

A-3:

B-1:

B-2:

B-3:

자외선 차단제는 MMA와 BMA의 총 함량 100중량부에 대한 중량부임MMA: methyl methacrylate
BMA: butyl methacrylate
A-1:

(R < ₁ > = H)
A-2:

A-3:

B-1:

B-2:

B-3:

The ultraviolet screening agent is a weight per 100 parts by weight of the total amount of MMA and BMA

One side of the polymethyl methacrylate (PMMA) film prepared above was subjected to corona discharge treatment and then bonded to one surface of the polarizer using an aqueous adhesive containing polyamine. On the other surface of the polarizer, a triacetyl cellulose film subjected to saponification treatment was bonded using an aqueous adhesive to prepare a polarizing plate.

Test Example

The properties of the polarizing plates prepared in the above Examples and Comparative Examples were measured and the results are shown in Table 2 below.

The prepared polarizing plate was irradiated with light having a wavelength of 365 nm, and the transmittance was measured.

<Evaluation Criteria>

?: Transmittance of a 365 nm wavelength to a polarizing plate sample is 0

X: Transmittance of the 365 nm wavelength to the polarizing plate sample is not 0

Further, a surface protective film containing a pressure-sensitive adhesive was bonded to a polymethyl methacrylate (PMMA) film of a polarizing plate, and the film was allowed to stand at 60 DEG C for 1 hour. After the surface protective film was removed, the polarizing plate was irradiated with light having a wavelength of 365 nm to measure the transmittance again.

<Evaluation Criteria>

○: No change in transmittance of the polarizer before / after leaving

X: Change in transmittance of polarizer before and after leaving

division UV blocking property (change in permeability) After polarizer production After removing the surface protection film Example 1 ○ ○ Example 2 ○ ○ Example 3 ○ ○ Example 4 ○ ○ Example 5 ○ ○ Example 6 ○ ○ Comparative Example 1 × × Comparative Example 2 ○ × Comparative Example 3 ○ × Comparative Example 4 ○ ×

As shown in Table 2, the polarizing plates of Examples 1 to 6, in which the ultraviolet absorbing copolymerizable monomers according to the present invention were copolymerized acrylate-based films as the polarizer protective film, had a UV blocking effect even after they were made into films, It was confirmed that the volatilization and decomposition of the ultraviolet absorbing copolymerizable monomer did not occur.

Further, it was confirmed that the deterioration of ultraviolet barrier property did not occur with the change with time.

Claims (6)

At least one ultraviolet absorbing group selected from the group consisting of oxiphenone, benzotriazole, salicylic ester, benzophenone, cyanoacrylate, triazole, triazine, nickel complex salt and inorganic powder; And an ultraviolet absorbing copolymerizable monomer having at least one copolymerizable functional group selected from the group consisting of a (meth) acrylic group, a vinyl group, an allyl group and a styryl group.
The acrylate-based film according to claim 1, wherein the ultraviolet absorbing group of the ultraviolet absorbing copolymerizable monomer is at least one selected from the group consisting of oxyphenone-based, benzotriazole-based, and triazine-based ultraviolet absorbing copolymerizable monomers.
The ultraviolet light absorbing copolymer composition according to claim 2, wherein the ultraviolet absorbing copolymerizable monomer

(R ₁ is H or CH ₃ ),

And

Wherein the acrylate-based film is at least one selected from the group consisting of acrylate-based films.
The acrylate-based film of claim 1, wherein the acrylate-based film comprises: 1) methyl methacrylate; 2) polymerizable monomers; And 3) at least one ultraviolet absorbing group selected from the group consisting of oxiphenone, benzotriazole, salicylic ester, benzophenone, cyanoacrylate, triazole, triazine, nickel complex salt and inorganic powder, and (Meth) acrylic group, a vinyl group, an allyl group, and a styryl group. The acrylate-based film is obtained by copolymerizing an ultraviolet absorbing copolymerizable monomer having at least one copolymerizable functional group selected from the group consisting of a (meth)
The acrylate-based film according to claim 4, wherein the acrylate-based film comprises 1) 45 to 98.9% by weight of methyl methacrylate, 2) 1 to 50% by weight of a polymerizable monomer, and 3) 0.1 to 5% by weight of an ultraviolet absorbing copolymerizable monomer Based on the total weight of the film.
Wherein at least one surface of the polarizer is laminated with the acrylate-based film according to any one of claims 1 to 5.