KR101542643B1 - Transparent plastic film comprising optically clear adhesive layer and method for producing it - Google Patents

Abstract

The present invention relates to a transparent plastic film in which a transparent base film layer is laminated on a pressure-sensitive adhesive film layer. More specifically, a transparent base film layer is laminated on a front surface and a back surface of a pressure- And is excellent in dimensional stability, flexural modulus and surface strength.

Description

TECHNICAL FIELD [0001] The present invention relates to a transparent plastic film comprising a pressure-sensitive adhesive layer and a method for producing the transparent plastic film,

The present invention relates to a transparent plastic film in which a transparent base film layer is laminated on a pressure-sensitive adhesive film layer. More specifically, a transparent base film layer is laminated on a front surface and a back surface of a pressure- And is excellent in dimensional stability, flexural modulus and surface strength.

The glass substrate used for display devices, picture frames, crafts, containers and the like has various advantages such as small coefficient of linear expansion, excellent gas barrier property, high light transmittance, surface flatness, excellent heat resistance and chemical resistance, Is high and has a heavy drawback.

In recent years, interest in liquid crystal, organic light emitting display, and electronic paper has rapidly increased, and research has been actively conducted to replace these substrates with glass.

Substituting a glass substrate with a plastic substrate with a basic plastic film and a functional coating layer can lighten the overall weight of the display device, provide design flexibility, and is resistant to impact. When manufactured by a continuous process, It can be economical.

On the other hand, in order to be used as a plastic substrate of a display device, a high glass transition temperature capable of withstanding the process temperature of the transistor device, the deposition temperature of the transparent electrode, oxygen and water vapor barrier properties to prevent aging of the liquid crystal and the organic light emitting material, A small coefficient of linear expansion and dimensional stability to prevent distortion of the substrate due to the change, high mechanical strength with compatibility with the processing equipment used in conventional glass substrates, chemical resistance that can withstand the etching process, high light transmittance and low birefringence, And scratch resistance of the surface.

However, since there is no high-performance polymer base film (including a polymer film and a polymer-inorganic composite film) satisfying all of these conditions, efforts have been made to satisfy the above-mentioned properties by applying a multi-layer functional coating to a polymer base film. Examples of the representative coating layer include an organic flattening layer for reducing defects on the polymer surface and imparting flatness, a gas barrier layer made of an inorganic material for gas blocking such as oxygen and water vapor, and a hard coating layer for imparting scratch resistance to the surface. In the case of many conventional multi-layer plastic substrates, the inorganic gas barrier layer is coated on the polymer substrate and the hard coating layer is coated on the gas barrier layer. In this multilayer structure, the large linear expansion coefficient between the polymer substrate and the gas barrier layer There is a problem that deformation of the polymer base material due to the difference and cracking and peeling of the inorganic thin film occur. Therefore, it is very important to design a suitable multi-layer structure capable of minimizing the stress at the interface of each layer and adhesion between the coating layers.

U.S. Patent No. 6,322,860 discloses a crosslinkable composition (polyfunctional acrylate-based monomer or oligomer, polyacrylate-based monomer or oligomer) containing silica particles or the like on one or both sides of a polyglutamidate sheet having a thickness of 1 mm or less, A crosslinking coating film is coated on the crosslinking coating film, and if necessary, the crosslinking coating film is further coated on the barrier film to form a plastic substrate for a display device . However, the dimensional stability that is essentially required for use as a glass substitute substrate in this patent has not been improved.

Therefore, there is a continuing need for development of a transparent plastic film having improved dimensional stability and flexural modulus while ensuring excellent transparency.

Accordingly, the present inventors have made efforts to develop an excellent transparent plastic film. As a result, they have found that a transparent substrate film layer is laminated on the front and back surfaces of an OCA (Optically clear adhesive) film layer, It is possible to improve the dimensional stability and the flexural modulus while securing transparency, and thus the present invention has been completed.

Accordingly, an object of the present invention is to provide a transparent plastic film having excellent transparency and improved dimensional stability and flexural modulus, and a method for producing the same.

To achieve the above object, the transparent plastic film of the present invention comprises: an adhesive film layer formed of a pressure-sensitive adhesive resin composition; A first transparent base material film layer formed on the entire surface of the adhesive film layer and a second transparent base material film layer formed on a back surface of the adhesive film layer; And a first hard coating film layer formed on the entire surface of the first transparent base film layer and a second hard coating film layer formed on a rear surface of the second transparent base film layer.

The method for producing a transparent plastic film according to the present invention comprises the steps of: curing a pressure-sensitive adhesive resin composition to produce a pressure-sensitive adhesive film layer; Laminating a first transparent base film layer on the entire surface of the adhesive film layer and a second transparent base film layer on the back surface of the adhesive film layer; And coating a hard coating solution on the entire surface of the first transparent base film layer and the rear surface of the second transparent base film layer, and curing the hard coating solution.

The transparent plastic film of the present invention can be used as a substitute for tempered glass in display products such as mobile and tablet because the surface hardness of the hard coating layer is excellent while maintaining the light transmittance of 90% have.

In particular, the transparent plastic film of the present invention is advantageous in that it has a large number of layers and is excellent in dimensional stability and has a high flexural modulus due to tensile elasticity of the adhesive film layer.

1 shows a laminated structure of the transparent plastic film of the present invention.
Fig. 2 is a photograph of the transparent plastic film produced in Example 1. Fig.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Hereinafter, a transparent plastic film according to an embodiment of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

Transparent plastic film

The transparent plastic film of the present invention comprises an adhesive film layer formed of a pressure-sensitive adhesive resin composition; A first transparent base material film layer formed on the entire surface of the adhesive film layer and a second transparent base material film layer formed on a back surface of the adhesive film layer; And a first hard coating film layer formed on the entire surface of the first transparent base film layer and a second hard coating film layer formed on a rear surface of the second transparent base film layer.

The adhesive film layer 100 is an optically clear adhesive (OCA) film layer, which is formed of a pressure-sensitive adhesive resin composition and includes a photopolymerizable compound that can be polymerized by irradiation with ultraviolet rays or electron beams. Preferably, the compound includes a modified acrylate compound having at least one double bond in the structure, more preferably 2-ethylhexyl acrylate (2-EHA), hydroxyethyl acrylate (HEA ), Acrylic acid (acrylic acid) and the like can be used.

The pressure-sensitive adhesive resin composition may include a photopolymerization initiator for photopolymerization, and initiates a photopolymerization reaction by absorbing an electron beam or ultraviolet energy to generate radicals.

Examples of the photopolymerization initiator include benzophenone, N, N'-tetramethyl-4,4'-diaminobenzophenone (Michler's ketone), N, N'-tetraethyl-4,4'-diaminobenzophenone, 4 2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2,2-dimethoxy-1,2-diphenyl-ethane Methyl-1- (4- (methylthio) phenyl) -2-morpholinopropanone-1,2,4-diethylthioxane Benzoin ethers such as benzoin methyl ether, benzoin ethyl ether and benzoin phenyl ether, benzoin such as methyl benzoin and ethyl benzoin, benzyl dimethyl ether such as benzyl dimethyl ether (O-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (o-fluorophenyl) -4,5-phenylimidazole dimer, 2- - (P-methoxyphenyl) -5-phenylimidazole dimer and 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, 2,4- 2,4,5-triarylimidazole dimer such as 4,5-diphenylimidazole dimer, 9-phenylacridine and 1,7-bis (9,9'-acridinyl) heptane , And bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide.

Although the amount of the photopolymerization initiator is not particularly limited, it is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the photopolymerizable compound. When the amount is less than the above range, there is a problem that sufficient curing reaction does not proceed even though light is irradiated, leaving unreacted compounds. When the amount is above the above range, the reaction is abruptly occurred upon irradiation with light,

The degree of adhesion of the pressure-sensitive adhesive film can be controlled according to the degree of polymerization, and a bending elastic force can be imparted to the entire plastic film.

Next, the first transparent base film layer 110 is formed on the entire surface of the adhesive film layer, and the second transparent base film layer 120 is formed on the back surface of the adhesive film layer.

The transparent base film layer may be formed of a resin selected from (a) a polyalkyl methacrylate or a polyalkyl acrylate, (b) a polycarbonate or a polyester carbonate, and (c) a polyalkylene terephthalate, The transparent base film layer and the second transparent base film layer may be formed of the same or different resins.

The (a) polyalkyl methacrylate or polyalkyl acrylate preferably contains an alkyl group having 1 to 12 carbon atoms and has a weight average molecular weight of 50,000 to 200,000, preferably 70,000 to 100,000, and most preferably, Polymethyl methacrylate (poly methyl methacrylate) is preferably used.

The polycarbonate or polyester carbonate (b) preferably has a weight average molecular weight of 10,000 to 50,000, preferably 15,000 to 35,000, and (c) the polyalkylene terephthalate contains an alkylene group having 2 to 8 carbon atoms And has a weight average molecular weight of 10,000 to 50,000.

The first hard coating layer 130 is formed on the front surface of the first transparent substrate film layer 110 and the second hard coating layer 140 is formed on the rear surface of the second transparent substrate film layer 120. The hard coating layer may be formed from a hard coating liquid, in which a thermosetting or photocurable compound is dissolved in a solvent. However, in the case of a thermosetting compound, when heat is applied to form a hard coating layer, the physical properties of the transparent base film layer and the adhesive film layer can be changed by heat, so that it is more preferable to use a photo-curable compound. In this case, the first hard coating layer and the second hard coating layer may be formed of a coating solution in which different compounds are dissolved, but it is preferable that the first hard coating layer and the second hard coating layer are formed of a coating solution in which the same compound is dissolved.

The photo-curable compound may be a monomer or oligomer having at least one functional group such as an unsaturated bond group capable of performing a crosslinking reaction, and examples thereof include urethane acrylate, epoxy acrylate, polyether acrylate, polyester acrylate, Dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, and the like can be used as the curing accelerator. In the present invention, these can be used alone or as a mixture of two or more of them as a photo-curable compound for forming a hard coat layer.

The hard coating liquid containing the photo-curable compound generally contains a photopolymerization initiator in addition to the photo-curable compound and the solvent. If necessary, various additives such as a light stabilizer and a leveling agent may be added to the hard coat layer May be included.

The first hard coating film layer and the second hard coating film layer have a surface hardness of 7H or more as measured by pencil hardness and show excellent surface hardness of the surface of the plastic film and more preferably in a range of 7H to 8H It is good to do.

Accordingly, the transparent plastic film of the present invention exhibits excellent dimensional stability and flexural modulus while exhibiting light transmittance of 90% or more.

Method of manufacturing transparent plastic film

In the method for producing a transparent plastic film of the present invention,

Curing the pressure-sensitive adhesive resin composition to produce a pressure-sensitive adhesive film layer;

Laminating a first transparent base film layer on the entire surface of the adhesive film layer and a second transparent base film layer on the back surface of the adhesive film layer; And

Coating a hard coating solution on the entire surface of the first transparent base film layer and the back surface of the second transparent base film layer and curing the hard coating solution

And a control unit.

First, the adhesive resin composition is cured to produce an adhesive film, and the degree of adhesion can be changed by adjusting the amount of UV irradiation.

Next, a transparent base film layer is laminated on the front and back surfaces of the adhesive film layer, respectively, and the transparent base film layers may be formed of the same or different resin.

Next, a hard coating solution is coated on the entire surface of the first transparent base film layer and the rear surface of the second transparent base film layer and cured to form a hard coating layer. The coating may be coated with a thin film by applying a coating method such as flow coating, dip coating, spin coating, spray coating or the like, , A hard coat layer exhibiting excellent surface hardness can be produced.

Hereinafter, the transparent plastic film of the present invention will be described in detail with reference to the preferred embodiments of the present invention.

The following examples and comparative examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example  One

And 0.7 parts by weight of cyclohexyl phenyl ketone (photoinitiator) were mixed with 100 parts by weight of hydroxyethyl acrylate as an acrylate compound to obtain a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition was bar-coated onto 100 탆 PET web and irradiated with UV for 3 minutes to cure To prepare an OCA film layer 100 having a thickness of 50 占 퐉.

Next, a 0.5 mm thick polymethyl methacrylate (weight average molecular weight: 80,000) film was prepared by extrusion molding and laminated on the front and back of the OCA film layer to form a transparent substrate film layer .

Then, a hard coating solution containing 1.2 parts by weight of 2,2-azobisisobutyronitrile (V-60, Wako) (thermal initiator) relative to 100 parts by weight of urethane acrylate was coated on the surface of the OCA film layer Coated on the entire surface of the transparent base film layer and the rear surface of the transparent base film layer formed on the back surface of the OCA film layer, and then left in a convection oven at 60 DEG C for 5 minutes. Next, the coated surface was irradiated with UV for 3 minutes to prepare a final transparent plastic film (PMMA / OCA / PMMA).

Example  2

A transparent plastic film (PC / OCA / PMMA) was produced in the same manner as in Example 1, except that a 0.5 mm thick polycarbonate (weight average molecular weight 20,000) film was prepared through extrusion molding and laminated on the entire surface of the OCA film layer. .

Example  3

A transparent plastic film (PC / OCA / PET) was prepared in the same manner as in Example 1, except that a 0.5 mm thick polycarbonate (weight average molecular weight 20,000) film was prepared through extrusion molding and laminated on the front and back surfaces of the OCA film layer. PC).

Example  4

A polyethylene terephthalate (weight average molecular weight: 20,000) film having a thickness of 0.5 mm was prepared by extrusion molding, and a transparent plastic film (PET / OCA / PET).

Example  5

A polyethylene terephthalate (weight average molecular weight: 20,000) film having a thickness of 0.5 mm was prepared by extrusion molding and a transparent plastic film (PET / OCA / PMMA) was prepared in the same manner as in Example 1 except that the film was laminated on the entire surface of the OCA film layer. ).

evaluation

In order to measure the dimensional stability and the flexural elasticity of the transparent plastic film of the above-described embodiment, the following experiment was conducted.

1) Dimensional stability measurement: 85 ° C, RH 85%, 100 hours, and the rate of change of specimen length was measured in%.

2) Measurement of Flexural Modulus: A 3-point bending test was performed based on ASTM D790.

The measurement results are shown in Table 1 below.

sample Dimensional stability (%) Flexural modulus (GPa) Example 1 0.25 3.7 Example 2 0.27 3.7 Example 3 0.29 3.5 Example 4 0.29 3.6 Example 5 0.28 3.6

As a result of the above experiment, it was confirmed that the transparent plastic film of the present invention can exhibit excellent dimensional stability of less than 0.3% and excellent flexural modulus of about 3.7 GPa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. . Accordingly, the true scope of the present invention should be determined by the following claims.

100: adhesive film layer 110: first transparent substrate film layer
120: second transparent base film layer 130: first hard coating layer
140: Second hard coating layer

Claims (10)

A pressure-sensitive adhesive film layer formed of a pressure-sensitive adhesive resin composition;
A first transparent base material film layer formed on the entire surface of the adhesive film layer and a second transparent base material film layer formed on a back surface of the adhesive film layer; And
A first hard coating film layer formed on the entire surface of the first transparent base film layer and a second hard coating film layer formed on a rear surface of the second transparent base film layer,
Wherein the pressure-sensitive adhesive resin composition comprises a modified acrylate-based compound having at least one double bond in its structure and a photopolymerization initiator, wherein the photopolymerization initiator is 0.01 to 10 parts by weight based on 100 parts by weight of the acrylate-
(A) a polyalkyl methacrylate or polyalkyl acrylate having a weight average molecular weight of 50,000 to 200,000, (b) a poly (alkyl acrylate) having a weight average molecular weight of 10,000 to 50,000, and Carbonate or polyester carbonate and (c) a polyalkylene terephthalate having a weight average molecular weight of 10,000 to 50,000,
Wherein the film has a flexural modulus of 3.5 to 3.7 GPa and a dimensional stability of not more than 0.3%, which is a rate of change in length measured at 85 ° C and RH 85% for 100 hours.
delete delete delete The method according to claim 1,
Wherein said polyalkyl methacrylate is polymethyl methacrylate.
delete delete The method according to claim 1,
Wherein the first hard coating film layer and the second hard coating film layer are formed from a hard coating solution comprising a thermosetting or photocurable compound.
9. The method of claim 8,
Wherein the first hard coating film layer and the second hard coating film layer have a surface hardness measured by pencil hardness of 7H or more.
Curing the pressure-sensitive adhesive resin composition by light irradiation to produce a pressure-sensitive adhesive film layer;
Laminating a first transparent base film layer on the entire surface of the adhesive film layer and a second transparent base film layer on the back surface of the adhesive film layer; And
Coating a hard coating solution on the entire surface of the first transparent base film layer and the rear surface of the second transparent base film layer and curing the hard coating solution,
Wherein the pressure-sensitive adhesive resin composition comprises a modified acrylate-based compound having at least one double bond in its structure and a photopolymerization initiator, wherein the photopolymerization initiator is 0.01 to 10 parts by weight based on 100 parts by weight of the acrylate-
(A) a polyalkyl methacrylate or polyalkyl acrylate having a weight average molecular weight of 50,000 to 200,000, (b) a poly (alkyl acrylate) having a weight average molecular weight of 10,000 to 50,000, and Carbonate or polyester carbonate and (c) a polyalkylene terephthalate having a weight average molecular weight of 10,000 to 50,000,
Wherein the film has a flexural modulus of 3.5 to 3.7 GPa and a dimensional stability of not more than 0.3%, which is a rate of change in length measured at 85 DEG C and RH 85% for 100 hours.

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