KR20120053670A - Polyester-based optical film - Google Patents

Abstract

PURPOSE: A polyester-based film is provided to comprise anionic surfactant and non-ionic surfactant on a primer layer, thereby having excellent adhesion with a substrate film after drying high temperature and high humidity condition and easily controlling adhesion with a substrate which has polar surface energy. CONSTITUTION: A polyester-based film comprises a polyester substrate film, and a primer layer formed on one side or double sides of the substrate film. The primer layer comprises a polyurethane based binder resin, an anionic surfactant, a non-ionic surfactant, silica nanoparticles and a hardener. The weight ratio of the anionic surfactant and the non-ionic surfactant is 4:6 - 2:8. The amount of the binder resin is 10.0-95.0 weight% on the basis of total weight of the primer layer.

Description

Polyester-based optical film {Polyester-based Optical Film}

The present invention relates to a polyester-based optical film, and more particularly to a polyester-based optical film comprising a polyester base film and a primer layer formed on one side or both sides of the base film, wherein the primer layer is anionic It relates to a polyester-based optical film, including a surfactant and a non-ionic surfactant, easy to control adhesion with a substrate having a polar surface energy, while maintaining the adhesion to the substrate film even after drying in high temperature, high humidity conditions .

In general, polyester films have excellent dimensional stability, thickness uniformity, and optical transparency, and thus are widely used for various industrial materials as well as display devices.

In the case of a functional polyester-based base material, the primer layer has often used the copolyester-type resin (binder) excellent in adhesiveness with a polyester-based base material. The adhesiveness with the film which is a polyester base material only with such a copolyester-type resin is enough. However, heat and moisture resistance adhesion is inferior, and easily adhesive property is lacking when post-processing, such as a prism processing layer, a lens processing layer, an antireflection layer, or a hard coating layer which is another base material.

Recently, in order to solve the above problems, acrylic or polyurethane-based binders are additionally introduced to provide excellent heat and moisture resistance, and are excellent in various UV curable resins and adhesives used in post-processing, and in terms of luminance by increasing refractive index. The development of optical recipes is progressing a lot.

However, in the case of the acrylic or polyurethane-based binder, even if the heat-resistance and easy adhesion to the UV curable resin at the time of post-processing, even when the adhesion test is carried out, various polyester laminates as the base layer under high temperature and high humidity environment There is a problem that the primer layer is separated from the polyester base layer due to the lack of adhesion with the film.

Thus, the present inventors in the Dongrae optical film composed of a polyester base film and a primer layer, when the anionic surfactant and nonionic surfactant is added to the primer layer, it is easy to control the adhesion with the substrate having a polar surface energy After drying under high temperature and high humidity conditions, it was confirmed that the adhesive force with the base film was also excellent, which led to the present invention.

It is an object of the present invention to include an anionic surfactant and a nonionic surfactant in a primer layer, so that it is easy to control adhesion with a substrate having a polar surface energy and has excellent adhesion to the substrate film after drying under high temperature and high humidity conditions. It is to provide an ester optical film.

Polyester-based optical film of the present invention for achieving the above object is a polyester-based optical film comprising a polyester base film and a primer layer formed on one side or both sides of the base film, the primer layer is water dispersion It is characterized by containing a PU-based binder resin, anionic surfactant, nonionic surfactant, silica nanoparticles and a curing agent.

The weight ratio of the anionic surfactant to the nonionic surfactant is preferably 4: 6 to 2: 8.

The binder resin is preferably included in 10.0 ~ 95.0% by weight based on the total weight of the primer layer.

It is preferable that the average particle diameter of the said silica nanoparticle is 10-300 nm.

The base film is preferably a thickness of 50 ~ 500㎛.

The surface of the base film on which the primer layer is formed has a total light transmittance of 85% or more and a haze value of 0.3 to 2%.

The adhesion between the base film and the primer layer is maintained at 90% or more even after a 96 hours moisture resistance test under 65 ℃ / 95% humidity.

The present invention forms a primer layer formed by mixing a surfactant and a polymer resin on a transparent polyester substrate film, thereby forming a primer layer that can easily control adhesion with a substrate having a polar surface energy, and has a high temperature and high humidity. Even after drying under conditions, the adhesive force with the base film satisfies 90% or more before drying.

Polyester-based optical film of the present invention is a polyester-based optical film comprising a polyester base film and a primer layer formed on one side or both sides of the base film, the primer layer is a water dispersion PU-based binder resin, anion It is characterized by containing a surfactant, a nonionic surfactant, silica nanoparticles and a curing agent.

The type of polyester film used in the present invention may be used without particular limitation as long as it is a conventional resin known as an optical base film to which a primer coating is applied. In the present invention, polyethylene terephthalate, polybutylene terephthalate, polyethylene or Although described mainly with respect to polyester resins such as phthalates, it will be understood that the present invention is not limited thereto.

The said polyester film points out the polyester obtained by polycondensing aromatic dicarboxylic acid and aliphatic glycol, and aromatic dicarboxylic acid uses terephthalic acid, 2, 6- naphthalenedicarboxylic acid, etc., and the said co-polyester

As the dicarboxylic acid component, isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, P-oxybenzoic acid, etc.) can be used. In addition, as an aliphatic glycol, ethylene glycol and diethyl

Len glycol, 1, 4- cyclohexane dimethanol, propylene glycol, butanediol, neopentylglycol, etc. are mentioned, These dicarboxylic acid component and glycol component may use 2 or more types together, respectively.

Representative polyester films include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like, and copolymers containing a third component in the polyester may be used.

The polyester resin of the above-described configuration is melted by an extruder after vacuum drying, extruded into a sheet through a T-DIE, adhered to a casting drum by pinning to a cooling roll, and solidified by cooling to unstretched. Polyester sheet

The uniaxially stretched polyester film is obtained by carrying out the uniaxial stretching of 2.5-4.5 times by the circumferential speed ratio difference between a roll and a roll in the roll heated above the glass transition temperature of a polyester resin.

The base film is preferably a thickness of 50 to 500㎛. If the thickness does not reach 50 µm, the adhesion between the substrate and the UV resin layer is lowered, which is not preferable. If the thickness exceeds 500 µm, the transmittance is lowered and the haze increases as the optical film.

As the binder used in the primer layer of the present invention, a water-dispersible polyurethane (PU) resin is used. In the present invention, the urethane resin refers to a compound represented by Formula 1 below:

Formula 1

(Wherein R is a hydroxy group, an amine group or an aryl group, m is an integer from 0 to 10, n is an integer of 1 or more.)

The binder resin is preferably included in 10.0 ~ 95.0% by weight based on the total weight of the primer layer. If the content of the binder resin does not reach 10% by weight, it is not preferable because the adhesion to the base layer is lowered. If the content of the binder resin exceeds 95% by weight, the content of the curing agent is lowered, which may increase the adhesiveness of the primer layer.

In the polyurethane binder of the present invention, a crosslinking agent may be used as necessary to improve durability. As a crosslinking agent of the said objective, any one selected from the group which consists of a melamine type compound, an epoxy type compound, an isocyanate type, and an oxazoline type compound contains 1.0-25 weight%. At this time, if it is less than 1.0% by weight, the crosslinking reaction is insufficient and the durability is lowered. If it exceeds 25% by weight, there is a problem that durability is poor due to excessive increase in the degree of curing and self-reaction of the curing agent.

A surfactant is used to apply a water-soluble coating solution onto a base film, which is a polyester film, which is applied to the base film using an appropriate amount of anionic and nonionic surfactants to increase the wettability of the base film and uniformly apply the coating solution. It is desirable to.

Anionic surfactants usable in the present invention include sulfates such as alkyl sulfates and alkyl ether sulfates; Sulfonates such as dioctyl sodium sulfosuccinate, sulfonate fluorosurfactant, and alkylbenzene sulfonate; Phosphates such as alkyl aryl ether phosphates, alkylether sulfonates, phosphate fluorosurfactants; Carboxylates such as soap (metal salt of fatty acid) and carboxylate fluorosurfactant; Polymers of acrylic acid derivatives, polymers of methacrylic acid derivatives, maleic anhydride copolymers, and the like.

Meanwhile, nonionic surfactants usable in the present invention include aliphatic alcohols such as cetyl alcohol and stearyl alcohol; Polyoxyethylene glycol alkyl ethers such as octaethylene glycol monododecyl ether and pentaethylene glycol monododecyl ether; Polyoxypropylene glycol alkyl ethers; Glucoside alkyl ethers such as decyl glucoside, lauryl glycoside, octyl glucoside; Polyoxyethylene glycol alkylphenol ethers; Glycerol alkyl esters such as glyceryl laurylate; Polyoxyethylene glycol sorbitan alkyl esters; And copolymers of ethylene glycol and propylene glycol.

It is preferable that the weight ratio of the said anionic surfactant: nonionic surfactant is 4: 6-2: 8. If the content of the anionic surfactant does not reach the above ratio, it is not preferable because it inhibits the adhesion to the UV resin, and if it exceeds the above ratio, the surface tension of the system is increased, so that the appearance defects during coating and the adhesion to the substrate are decreased. Not.

In addition, in the present invention, an inorganic particle having a relatively small difference in refractive index with a resin may be added to the primer layer in order to improve coating properties and functionality. As the inorganic particles, alumina or silica nanoparticles may be used, and preferably, silica nanoparticles having a particle size in the range of 10 to 300 nm are used. If the average particle diameter is less than 10 nm, the fine inorganic particles not only help the running (or slip) and scratch resistance in the substrate, but also do not give an effect of the inorganic particle injection, and if the average particle diameter of the fine particles exceeds 300 nm Problems that cause haze are caused.

In addition, additives such as an antistatic agent and an antifoaming agent may be added to the primer layer.

In the polyester-based optical film of the present invention, the primer layer is preferably formed to a thickness of 0.01 to 5.00㎛, more preferably is formed to 0.05 to 3.00㎛. In this case, when the thickness of the primer layer is thinner than 0.01 μm, the transparency is good but the adhesive strength is reduced during post-processing, when the thickness of the primer layer is thicker than 5.00 μm, the adhesive property is excellent, but the transparency and the coating property are not preferable.

On the other hand, the method of applying the primer layer may be carried out by a method such as a meyer bar method, a gravure method, and by applying a polar group on the surface of the film before application, adhesion or coating property of the coating layer and the film. Corona discharge treatments can be made for improvement.

From the above, the optical film of the present invention is provided with a primer layer excellent in adhesion to the polyester base film layer, so that the adhesion between the base film and the primer layer after 96 hours moisture resistance test under the conditions of 65 ℃ / 95% humidity It is maintained above 90%. That is, even if the optical film according to the present invention is exposed to an environment of high temperature and high humidity after a post-processing process such as a prism, a lens or a hard coating, the adhesiveness can be improved more than before. In addition, the primer layer of the present invention, by using a photoinitiator in the urethane resin containing a functional group capable of dispersed photoreaction, increases the adhesion to the UV-curable resin coated on the primer layer when processing the radical or ring-opening reaction, Due to network formation, durability also plays a role.

On the other hand, the surface of the base film on which the primer layer is formed has a total light transmittance of 85% or more and a haze value of 0.3 to 2%.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention. These examples are only presented by way of example only to more specifically describe the present invention, it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by these examples. .

Example 1

Urethane resin (Cytec Surface Specialties, Daotan VTW1236, MW 50,000,) forming the primer layer is an aqueous dispersion containing 70% by weight of water and 30% by weight of urethane resin, 20.0% by weight, and a melamine-based curing agent to improve moisture resistance. (Sanwa Chemical, MW12LF, MW 340) mixed 63.9% by weight of water with 5% by weight of an aqueous dispersion containing 30% by weight in 70% by weight of water, and colloidal silica particles (Nalko, SW-140, average particle diameter 140nm). ) Was prepared using a 0.1% by weight aqueous dispersion containing 30% by weight of water and 70% by weight of colloidal silica particles.

At this time, the anionic surfactant (DuPont, Zonyl FS610) is 90% by weight of water and 10% by weight of an aqueous surfactant containing 0.45% by weight aqueous dispersion, nonionic surfactant (air product, Dynol607) 90% Mix and stir 0.05% by weight of an aqueous dispersion containing 10% by weight of water and 10% by weight of a nonionic surfactant, and prepare a coating solution such that the weight ratio of anionic to nonionic surfactant is 9: 1, as shown in Table 1. , # 3 using a Mayer bar was applied to one surface of a polystyrene terephthalate film to prepare an optical film.

[Example 2]

An optical film was prepared in the same manner as in Example 1, except that the coating solution was formed so that the weight ratio of the anionic to nonionic surfactant was 7: 3.

[Example 3]

An optical film was prepared in the same manner as in Example 1, except that the coating solution was formed such that the weight ratio of the anionic to nonionic surfactant was 5: 5.

 Example 4

An optical film was prepared in the same manner as in Example 1, except that the coating solution was formed so that the weight ratio of anionic to nonionic surfactant was 3: 7.

 [Example 5]

An optical film was prepared in the same manner as in Example 1, except that the coating solution was formed so that the weight ratio of the anionic to nonionic surfactant was 1: 9.

Comparative Example 1

An optical film was prepared in the same manner as in Example 1, except that the crude crude solution to which the anionic surfactant was added and no nonionic surfactant was included.

Comparative Example 2

An optical film was prepared in the same manner as in Example 1, except that a polyurethane crude liquid to which a nonionic surfactant was added and no anionic surfactant was included.

[Experimental Example]

The physical properties of the films prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were measured as described below, and are shown in Table 1 below.

1.Measurement of the thickness of the primer layer

Primer layer thicknesses of the scientific films prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were measured using a micrometer-based sedimentation measuring instrument [Mitsutoyo Co., Model: ID-Ff125], 10 sheets The value obtained by subtracting the thickness of the transparent base film from the total thickness measurement of was calculated by dividing by 10.

2. Measurement of surface energy

Surface energy of the primer layer prepared in Examples 1 to 5 and Comparative Examples 1 and 2 was measured using the water contact angle on the optical film. At this time, the solvent used was calculated by separating the surface energy into polar / non-polarity using the harmonic-average equation represented by the following equation for the water contact angle measured in each of distilled water (H ₂ O) and CH ₂ I ₂ .

(1 + cosθ) γ _l = 4 (γ _l ^d γ _s ^d / γ _l ^d + γ _s ^d + γ _l ^p γ _s ^p / γ _l ^p + γ _s ^p )

In the above, θ: contact angle, γ _l : surface energy of liquid, γ _s : surface energy of solid, γ ^d : nonpolar surface energy, γ ^p : polar surface energy.

3. Confirmation of adhesion

The adhesion between the substrate and the primer layer of the film prepared in Examples 1 to 5 and Comparative Examples 1 and 2 was measured. Apply acrylic UV cured resin to the surface to which the primer layer is bonded using a # 20 wire bar, and then use a cutter to make a cutting line on the film coated with the primer layer, and then to a 10 × 10 matrix, 2 mm × 2 mm. Place the squares. The cellophane tape (No. 405, product of NICHIBAN; width: 24 mm) is stuck to the film with a cutting line, and it adheres strongly to a film by rubbing a tape using velvet. Then remove the tape vertically. The area of the primer layer remaining in the adhesive layer was visually observed, and the adhesive force was calculated by the following equation.

Adhesion (%) = [1- (area of peeled antistatic layer) / (single area)] x 100

In addition, the adhesion test for evaluation of moisture resistance after 96 hours at 65 ° C. and 90% humidity was also performed in the same manner as above.

4. Coating Check

In Example 1 to 5 and Comparative Examples 1 and 2, the coating property between the coating liquid and the base material as the primer layer was measured. A primer layer is applied to the substrate using a wire bar to confirm that the primer layer is coated on the entire surface of the substrate. Visually, the coating property was evaluated to be excellent when there were less than two of 100 square pieces (one square: 1 × 1 mm) such as islands.

The above evaluation results are summarized in Table 1 below.

division Anionic: Nonionic Surfactant Weight Ratio Polar / Non-polar Surface Energy Ratio Adhesion (%) High temperature and high humidity
Adhesion (%) Coating
(O: good
Δ: normal
X: bad) Example 1 9: 1 1: 1.8 78 73 Δ Example 2 7: 3 1: 2.1 82 80 O Example 3 5: 5 1: 2.3 90 85 O Example 4 3: 7 1: 2.5 100 100 O Example 5 1: 9 1: 2.8 95 90 O Comparative Example 1 1: 0 1.1.6 69 50 Δ Comparative Example 2 0: 1 1.2.7 86 81 O PET - 1: 2.5 - - - PEN - 1.2.6 - - -

As shown in Table 1, when the optical film is manufactured using the same primer layer as the nonpolar / polar surface energy ratio of the substrate, the adhesion to the substrate is improved, and thus the adhesiveness is maintained even in a high temperature and high humidity environment. Production of an ester optical film was possible.

While the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the invention, and such modifications and variations belong to the appended claims.

The polyester optical film of the present invention has an adhesive force between a substrate and a primer layer in a product to which functionality is given, such as a substrate for an LCD backlight unit or a substrate for a prism sheet, a substrate for various hard coat processing or anti-reflection, etc. Can be used to increase

Claims (9)

In the polyester-based optical film comprising a polyester base film and a primer layer formed on one side or both sides of the base film,
The primer layer is a polyester optical film comprising a water-based PU binder resin, anionic surfactant, nonionic surfactant, silica nanoparticles and a curing agent. The method of claim 1, wherein the anionic surfactant is selected from the group consisting of sulfates such as alkyl sulfates, alkyl ether sulfates; Sulfonates such as dioctyl sodium sulfosuccinate, sulfonate fluorosurfactant, and alkylbenzene sulfonate; Phosphates such as alkyl aryl ether phosphates, alkylether sulfonates, phosphate fluorosurfactants; Carboxylates such as soap (metal salt of fatty acid) and carboxylate fluorosurfactant; Polymers of acrylic acid derivatives; Polymers of methacrylic acid derivatives; And at least one selected from the group consisting of maleic anhydride copolymers. According to claim 1, The nonionic surfactant is aliphatic alcohol, such as cetyl alcohol, stearyl alcohol; Polyoxyethylene glycol alkyl ethers such as octaethylene glycol monododecyl ether and pentaethylene glycol monododecyl ether; Polyoxypropylene glycol alkyl ethers; Glucoside alkyl ethers such as decyl glucoside, lauryl glycoside, octyl glucoside; Polyoxyethylene glycol alkylphenol ethers; Glycerol alkyl esters such as glyceryl laurylate; Polyoxyethylene glycol sorbitan alkyl esters; And at least one selected from the group consisting of copolymers of ethylene glycol and propylene glycol. The method of claim 1, wherein the weight ratio of the anionic surfactant: nonionic surfactant is 4: 6 to 2: 8, characterized in that the polyester optical film. The method of claim 1, wherein the binder resin is the polyester-based optical film, characterized in that contained in 10.0 to 95.0% by weight relative to the total weight of the primer layer. The method of claim 1, wherein the average particle diameter of the silica nanoparticles is 10 to 300nm, The polyester-based optical film, characterized in that. The method of claim 1, wherein the base film is a polyester-based optical film, characterized in that the thickness of 50 ~ 500㎛. The film of claim 1, wherein the surface of the base film on which the primer layer is formed has a total light transmittance of 85% or more and a haze value of 0.3 to 2%. The method of claim 1, wherein the adhesive force between the base film and the primer layer is maintained at 90% or more after 96 hours humidity resistance test at 65 ℃ 95% humidity, characterized in that the polyester optical film.