KR101149538B1 - Optical polyester film with primer layer easily controlling refraction index - Google Patents

Abstract

The present invention relates to an optical polyester film having a primer layer that is easy to control the refractive index, and more particularly, the primer layer used for the polyester film has a high refractive index in the primer layer as well as sufficient adhesiveness with the substrate. The present invention relates to an optical polyester film having a primer layer having an excellent refractive index adjustment which is excellent in characteristics such as surface hardness and scratch resistance by adding inorganic particles and which can minimize interference phenomena by high refractive index. To this end, the optical polyester film having a primer layer having an easy refractive index control according to the present invention is a transparent polyester base film drawn on at least one axis with a thickness of 50 to 500 μm, and is coated on at least one side of the base film. An optical polyester film having a primer layer having an easy refractive index control including a primer layer of a polymer adhesive layer, wherein the primer layer includes an acrylic polymer, a water-dispersed polyester copolymer or a polyurethane-based resin, and inorganic particles as a binder resin. And, the adhesion between the base film and the primer layer is characterized in that 95% or more.

Description

Optical polyester film having primer layer with easy refractive index control {OPTICAL POLYESTER FILM WITH PRIMER LAYER EASILY CONTROLLING REFRACTION INDEX}

The present invention relates to an optical polyester film having a primer layer that is easy to control the refractive index, and more particularly, the primer layer used for the polyester film has a high refractive index in the primer layer as well as sufficient adhesiveness with the substrate. The present invention relates to an optical polyester film having a primer layer having an excellent refractive index adjustment which is excellent in characteristics such as surface hardness and scratch resistance by adding inorganic particles and which can minimize interference phenomena by high refractive index.

In general, polyester films are excellent in dimensional stability, thickness uniformity, and optical transparency, so that they are widely used not only for display devices but also for various industrial materials. In particular, as the interest in liquid crystal displays, organic light emitting displays, and electronic papers has recently increased, studies are being actively conducted to replace the substrates of these display devices with polyester films instead of glass substrates. The reason for this is that replacing the glass substrate with a polyester film makes the overall weight of the display device lighter, gives design flexibility, and is more resistant to impact and can be manufactured in a continuous process. .

The development for such applications requires high glass transition temperature, high light transmittance and surface scratch resistance, and adhesion to the substrate and the post-coating liquid, which can withstand the deposition temperature of the transparent electrode.

In addition, such a polyester film is often subjected to a process of coating a hard coating layer on the surface, the problem when manufacturing such a structure is the deformation of the polyester film due to the large difference in coefficient of linear expansion between the polyester film and the hard coating layer Cracking and peeling may occur, and interference interference may occur due to light interference due to a difference in refractive index. Therefore, it can be said that it is very important to design the appropriate structure to minimize the stress at the interface of each layer, the adhesion between the coating layer, the coating thickness control according to the refractive index of the primer layer.

Such primer layers are often composed of an acrylic crude liquid and a composition of a polyester copolymer or a polyurethane resin (Korean Patent Publication No. 2010-0081568).

And since the adhesive force of the prior art consists of only the adhesion by the dispersing force, there is an attempt to solve this problem by using a primer such as a reactor.

In addition, interference interference occurs in the conventional low refractive index has attempted to solve by adjusting the refractive index of the primer layer.

In addition, there is an attempt to increase the surface hardness through the improvement of the curing degree, but there is a limit in the polymer material itself.

Korean Patent Publication No. 2010-0081568

The present invention has been made to solve the above problems, and an object of the present invention is to add an inorganic particle having a high refractive index to the primer layer, as well as sufficient adhesion to the base material primer layer used in the polyester film An object of the present invention is to provide an optical polyester film having a primer layer having excellent properties such as surface hardness and scratch resistance, and having an easy refractive index adjustment that can minimize interference phenomena due to high refractive index.

These and other objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof.

The above object is a primer layer that is easy to control the refractive index including a transparent polyester base film stretched in at least one axis having a thickness of 50 ~ 500㎛ and a primer layer of a polymer easily adhesive layer applied to at least one side of the base film An optical polyester film having, wherein the primer layer comprises an acrylic polymer, a water-dispersed polyester copolymer or a polyurethane-based resin and inorganic particles as a binder resin, the adhesion between the base film and the primer layer is 95% or more. It is achieved by the optical polyester film which has a primer layer which is easy to adjust the refractive index characterized by the above-mentioned.

Here, the primer layer is 10 to 90% by weight of the binder resin aqueous dispersion composed of 70% by weight of water and 30% by weight of acrylic polymer, polyester copolymer or polyurethane resin as the binder resin, 70% by weight of water and melanin 1 to 50% by weight of an aqueous dispersion of a curing agent composed of 30% by weight of an epoxy or epoxy-based curing agent, 0.1 to 10% by weight of a water dispersion of a surfactant consisting of 10% by weight of water and an anionic surfactant, and 30% by weight of water. It is applied with a coating liquid consisting of 0.1 to 40% by weight of the inorganic particle aqueous dispersion composed of 70% by weight of the inorganic particles and the remaining amount of water, and the coating thickness is 0.05 to 0.5㎛.

Preferably, the refractive index of the primer layer is characterized in that 1.55 or more.

Preferably, the inorganic particles are at least one of titanium oxide, titanium-organic composite, silica particles, and silica-organic composite, and have a size of 10 to 300 nm and a refractive index of 1.5 or more.

Preferably, the surface of the base film on which the primer layer is formed is characterized in that the total light transmittance is 90% or more, the haze value is 0.4 ~ 1.8%.

Preferably, the adhesion between the base film and the primer layer is characterized in that 95% or more after the 96 hours humidity resistance test at 65 ℃, 95% humidity.

Preferably, the pencil hardness of the primer layer is characterized in that 1H or more.

According to the present invention, by adding an inorganic particle having a high refractive index to at least one axially stretched transparent polyester base film to increase the refractive index to minimize the interference-mura phenomenon, it is possible to improve the productivity during post-processing, scratch resistance and surface The hardness can be increased, and the optical properties are excellent.

1 is a cross-sectional view of an optical polyester film having a primer layer easy to adjust the refractive index according to the present invention.
2 is a graph showing a change in refractive index according to the concentration of the inorganic particles according to the present invention.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings 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 skilled in the art that the scope of the present invention is not limited by these examples. .

The polyester film according to the present invention relates to an optical polyester film having a primer layer that minimizes interference phenomena after a post-processing process such as a prism, a lens, or a hard coating, and has an improved refractive index control with improved surface hardness and scratch resistance. will be. That is, the polyester film according to the present invention, unlike the conventional polyester film for optical refractive index control, by adding an inorganic particle having a high refractive index, such as titanium oxide to the binder constituting the primer layer, the original particle By using the refractive index, it is characterized in that the polyester film as a whole to increase the refractive index of the film so that the interference-mura phenomenon due to the coating liquid does not appear during the post-processing.

Optical polyester film having a primer layer that is easy to control the refractive index according to the present invention is a transparent polyester base film stretched in at least one axis with a thickness of 50 ~ 500㎛, and the polymer coated on at least one side of the base film An optical polyester film having a primer layer having an easy refractive index adjustment including a primer layer of an adhesive layer, wherein the primer layer includes an acrylic polymer, a water-dispersed polyester copolymer or a polyurethane-based resin, and inorganic particles as a binder resin, The adhesion between the base film and the primer layer is characterized in that more than 95%, wherein the addition of the inorganic particles to give a runability at the time of film forming a polyester film while using a refractive index of the particles to increase the refractive index of the primer layer It can be provided.

In addition, the primer layer is characterized in that the binder resin is applied with a coating liquid containing an acrylic polymer, polyester copolymer or polyurethane resin, melanin or epoxy curing agent, anionic surfactant and inorganic particles. Preferably

In addition, the acrylic polymer and the polyester copolymer or the polyurethane-based resin forming the optical polyester film having a primer layer with easy refractive index adjustment according to the present invention is preferably soluble or dispersible in water, in particular, the polyurethane-based resin The acrylic polymer of diol may be obtained by substitution polymerization, preferably copolymerization.

In addition, a surfactant is used for use in the water-soluble coating solution of the polyester film according to the present invention, and in order to increase the wettability of the base film and to uniformly apply the coating solution, a known amount of anionic or nonionic surfactant is used to the base film. It is preferable to apply.

Moreover, the primer layer which concerns on this invention is formed by apply | coating with a resin binder etc. on the film after uniaxial stretching of a polyester film. At this time, it is preferable that the thickness of the layer to which resin was apply | coated is 0.05-5 micrometers, More preferably, it is good to set it as 0.05-3.00 micrometers. When the thickness of the coating is thinner than 0.05㎛ the transparency is good but the adhesive strength during the post-processing, if thicker than 5㎛ because the adhesive properties are excellent, but the transparency and coating properties are not preferred because it is not preferable.

In addition, in the present invention, an additive may be used in the coating liquid to improve coating properties and functionality, and organic additives, inorganic particles, and antifoaming agents may be used as such additives. According to the present invention, the water-soluble polymer primer layer may include a binder resin and inorganic particles having a high refractive index, thereby ensuring runability. However, when the average particle diameter exceeds 500 nm, a haze may increase. Therefore, the size of the inorganic particles used in the present invention preferably has a particle size in the range of 10 ~ 300nm. The inorganic particles are at least one of titanium oxide, titanium-organic composite, silica particles, and silica-organic composite, and preferably have a refractive index of 1.5 or more.

In addition, the coating liquid constituting the primer layer in the optical polyester film having a primer layer easy to control the refractive index according to the present invention is 70% by weight of water and 30% by weight of the acrylic polymer, polyester copolymer or binder resin 10 to 90% by weight of a polymer resin aqueous dispersion composed of polyurethane resin, 70% by weight of water and 1 to 50% by weight of a curing agent aqueous dispersion composed of 30% by weight of melanin or epoxy curing agent, 90% by weight of water and anionic It is preferred that 0.1 to 10% by weight of the surfactant aqueous dispersion composed of 10% by weight of surfactant, 30% by weight of water and 0.1 to 40% by weight of the inorganic particle aqueous dispersion consisting of 70% by weight of inorganic particles and the remaining amount of water.

In addition, in the optical polyester film having a primer layer that is easy to control the refractive index according to the present invention, the surface of the base film on which the primer layer is formed has an adhesive strength of 95% or more, a light transmittance of 90% or more, and a haze of 0.4% to 1.8. %, The adhesion between the base film and the primer layer after a high temperature and high humidity condition of 96 hours at 65 ℃ 95% humidity is characterized in that more than 95%.

In addition, the optical polyester film having a primer layer easy to adjust the refractive index according to the invention is characterized in that the pencil hardness between the base film and the primer layer is 1H or more.

In addition, the optical polyester film having a primer layer that is easy to control the refractive index according to the present invention is characterized in that the refractive index of the base film on which the primer layer is formed is 1.55 or more.

Hereinafter, the present invention will be described in more detail with reference to Examples. This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

Example 1-5

The coating liquid for forming the primer layer is 20.0% by weight of a binder resin aqueous dispersion composed of 70% by weight of water and 30% by weight of polyurethane resin as a binder resin, 30% by weight of melamine-based curing agent and 70% by weight of water to improve moisture resistance. 5% by weight of the curing agent aqueous dispersion composed of 5% by weight and 63.9% by weight of water, 1.0% by weight of the aqueous surfactant dispersion consisting of 90% by weight of water and 10% by weight of anionic surfactant and titanium oxide particles (refractive index: 2.5) After the coating liquid was prepared using 1-10% by weight of an aqueous dispersion of inorganic particles consisting of 30% by weight of water and 70% by weight of titanium oxide particles and the remaining amount of water (see Table 1), a uniaxially stretched poly having a thickness of 100 μm was used. It was applied to an ester base film to prepare an optical polyester film with easy refractive index control. Application was applied using # 0 meyer bar.

division Titanium Particle Addition (%) Solid content (%) Viscosity (CPS) Example 1 One 7.18 1.18 Example 2 3 7.18 1.23 Example 3 5 7.18 1.5 Example 4 7 7.18 1.84 Example 5 10 7.18 1.92

[Comparative Example]

The coating was performed with the same resin as in Example, but as shown in Table 2, Comparative Example 1 added a crude liquid without adding titanium oxide particles, and Comparative Example 2 added silica particles having a low refractive index (refractive index: 1.5).

division Composition Solid content (%) Viscosity (CPS) Comparative Example 1 No inorganic particles added 7.18 1.08 Comparative Example 2 5% of silica particles added 7.18 1.42

The physical properties of the optical polyester films according to Examples 1 to 5 and Comparative Examples 1 and 2 were measured through the following experimental examples, and the results are shown in Table 3 below.

[Experimental Example]

1. Measurement of thickness of coating layer

The thickness of the coating layer of the polyester film for easy refractive index control prepared in Examples 1 to 5 and Comparative Examples 1 and 2 was measured using a micrometer using a pressure gauge [Mitsutoyo Co., Model: ID-Ff125]. It was measured, and was calculated as the average of the remaining values minus the thickness of the transparent base film from the thickness measurement value of a total of 10 sheets.

2. Refractive index measurement

Since the refractive indices of the coating layers prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were difficult to measure on the optical film, the coating liquid was coated on a Si wafer, and the refractive index was measured using Ellipsometry.

3. Confirmation of adhesion

The adhesion between the substrate and the primer layer of the films prepared in Examples 1 to 5 and Comparative Examples 1 and 2 was measured. Apply acrylic UV curable 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 apply a cut line of 2 mm x 2 mm to a matrix of 10 X 10. Place the squares. The cellophane tape (No. 405, width of NICHIBAN: 24 mm) is affixed to the film with a cutting line, and the tape is rubbed strongly with the film using velvet, and then the tape is removed 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.

(1)

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 Examples 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 # 0 to # 6 wire bars to confirm that the primer layer is coated on the entire surface of the substrate. Visually, it was evaluated that coating property was excellent when there were less than two parts on 100 small squares ((1 square: 1 x 1mm)) such as islands.

5. Haze / light transmittance check

After coating and thermosetting the 188 ㎛ PET film with the coating solution prepared in the experimental example, the haze and transmittance were measured using a HAZE meter manufactured by NIPPON DENSHOKU.

6. Pencil hardness measurement

Pencil hardness of the primer layer was measured in Examples 1 to 5 and Comparative Examples 1,2. According to JIS K 5600-5-4 (1999 edition), it measured using the pencil scraping tester (manual type) by Imoto Seisakusho Co., Ltd. make.

Experimental results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in the following Table 3 and the graphs of FIG. 2.

division Coating layer
Thickness (㎛) Refractive index Adhesion
(%) Moisture Adhesion (%) Coating Haze /
Light transmittance pencil
Hardness Example 1 0.15 1.55 100 97 0 0.49 /
92.9 1H Example 2 0.15 1.56 100 100 O 0.54
/91.4 1H Example 3 0.15 1.60 100 100 O 0.66 /
91.0 1 ~ 2H Example 4 0.15 1.62 100 100 O 0.87 /
90.9 2H Example 5 0.15 1.65 100 96 0 0.95 /
90.1 2H Comparative Example 1 0.15 1.45 90 80 0 0.38 /
89.2 1B Comparative Example 2 0.15 1.53 70 30 0 0.75 /
91.1 1H

(O: Good, Δ: Normal, X: Poor)

As shown in the graph of Table 3 and Figure 2, when the titanium film is added to prepare an optical film, it is possible to manufacture a polyester film for optics is easy to control high refractive index, there is no problem in adhesion. Moreover, when surface hardness also measured pencil hardness, 1H or more primer layer could be manufactured.

It is to be understood that the present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

Optical polyester film having a primer layer that is easy to control the refractive index according to the present invention can minimize the interference mura phenomenon to improve the productivity during post-processing, increase scratch resistance and surface hardness, and also excellent optical properties Therefore, it can be used widely also for protective films, such as an antireflection film and a liquid crystal display device.

Claims (7)

In the optical polyester film which has a primer layer which is easy to adjust refractive index,
Optical poly having a primer layer that can be easily adjusted in refractive index including a transparent polyester base film stretched in at least one axis with a thickness of 50 to 500 μm and a primer layer of a polymer easily adhesive layer applied to at least one side of the base film. As ester film,
The primer layer includes an acrylic polymer, a water-dispersed polyester copolymer or a polyurethane-based resin and titanium oxide particles as a binder resin,
The adhesion between the base film and the primer layer is 95% or more,
The refractive index of the said primer layer is 1.55-1.65, The optical polyester film which has a primer layer with easy refractive index adjustment. The method of claim 1,
The primer layer is 10 to 90% by weight of a binder resin aqueous dispersion composed of 70% by weight of water and 30% by weight of an acrylic polymer, a polyester copolymer or a polyurethane resin, and 70% by weight of water and a melanin-based binder resin. 1 to 50% by weight of an aqueous dispersion of a curing agent composed of 30% by weight of an epoxy-based curing agent, 0.1 to 10% by weight of a water dispersion of titanium and 90% by weight of water and titanium oxide. It is applied with a coating liquid consisting of 0.1 to 40% by weight of the aqueous dispersion of titanium oxide particles composed of 70% by weight of particles and the remaining amount of water, and the coating thickness is 0.05 to 0.5 µm. Polyester film. delete The method of claim 1,
Said titanium oxide particle is 10-300 nm in size, and refractive index is 1.5 or more, The optical polyester film which has a primer layer which is easy to adjust refractive index. The method of claim 1,
The surface of the base film on which the primer layer is formed has a total light transmittance of 90% or more and a haze value of 0.4 to 1.8%. The method of claim 1,
The adhesive force between the base film and the primer layer is 95% or more after a 96 hours humidity resistance test at 65 ° C. and 95% humidity, the optical polyester film having a primer layer with easy refractive index control. The method according to any one of claims 1 to 6,
Pencil hardness of the said primer layer is 1H or more, The optical polyester film which has a primer layer with easy refractive index adjustment.

Images