KR100959000B1 - Biaxially-oriented polyester laminated film for optical use - Google Patents

Abstract

The present invention relates to an optical biaxially oriented polyester laminated film, and more particularly, the primer layer used for the biaxially stretched polyester film is not only sufficient adhesiveness with the substrate, but also easily adhesiveness and high temperature required in the post-processing process. The present invention relates to an optical biaxially oriented polyester laminated film which is excellent in adhesion and optical properties when evaluating moisture resistance of high humidity, which can increase product yield, and can be used in various optical members. To this end, the biaxially oriented polyester laminated film for optics according to the present invention is based on a biaxially oriented polyester film having a thickness of 50 to 300 μm, and has a primer layer formed on at least one surface of the substrate as a polymer adhesive layer. As the film, the polymer primer layer comprises a copolyester resin comprising a branched monomer, a polyurethane resin, silica particles or alumina-silica composite oxide particles having an average particle diameter of 50 to 300 nm, and a curing agent, wherein the copolyester The weight ratio of the resin and the polyurethane-based resin is 90:10 to 10:90, the content of the silica particles or alumina-silica composite oxide particles is 0.01 to 60% by weight, the content of the curing agent is 1.0 to 40% by weight do.

Biaxially oriented polyester film, copolymerized polyester resin, silica particles, primer layer, total light transmittance, haze, moisture resistance, hardener

Description

Biaxially Oriented Polyester Laminated Film for Optics {BIAXIALLY-ORIENTED POLYESTER LAMINATED FILM FOR OPTICAL USE}

1 is a cross-sectional view of an optical biaxially oriented polyester laminated film according to the present invention.

The present invention relates to an optical biaxially oriented polyester laminated film, and more particularly, the primer layer used for the biaxially stretched polyester film is not only sufficient adhesiveness with the substrate, but also easily adhesiveness and high temperature required in the post-processing process. The present invention relates to an optical biaxially oriented polyester laminated film which is excellent in adhesion and optical properties when evaluating moisture resistance of high humidity, which can increase product yield, and can be used in various optical members.

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

When the biaxially stretched polyester laminated film is used for optics, the primer layer generally forms a primer layer from a copolyester-based resin having excellent adhesion with the polyester film. However, when the copolyester-based resin is used alone, the adhesion with the polyester base film is sufficient, but when used after various post-processing treatments such as a prism lens, an antireflection layer, or a hard coating layer, the copolyester-based resin is used. Insufficient In order to compensate for this, it is excellent in easily adhesiveness, flexibility and abrasion resistance when producing polyester, and has a strong adhesiveness, so that the adhesive layer is improved by coating a primer layer using a polyurethane-based resin which is used in many fields requiring adhesiveness. How to make is studied. However, by forming a primer layer made of a polyurethane resin, the adhesive strength with the outer layer such as a hard coat layer is improved, but the adhesive force with the polyester film as the base material is not sufficient, resulting in sufficient adhesiveness with the outer layer. There was a problem not to lose.

In addition, as one of the evaluation methods of the adhesiveness after the post-processing treatment, when evaluating the moisture resistance of the high temperature and high humidity at 65 ℃, 90% humidity conditions, a poor adhesion due to the penetration of moisture to the back surface after the post-processing treatment occurs, a study to compensate for this It's going on.

On the other hand, the biaxially stretched polyester film used for optics is required to have excellent adhesive properties for prism lens processing, hard coat processing, AR processing, but it is difficult to develop because the resin form used for each post-processing company is different. As well as. It is desired that the biaxially stretched polyester film used for such optics be very small in foreign matters included in the film which causes scratch resistance and optical defects, and such an optical film is also required to have excellent transparency.

The present invention has been made to solve the above problems and to meet the conventional requirements, the object of the present invention is a primer layer used in biaxially stretched polyester film, as well as sufficient easy adhesion with the substrate, the post-processing process It is to provide an excellent biaxially oriented polyester laminated film having excellent properties such as easy adhesion, excellent adhesive strength when evaluating moisture resistance of high temperature and high humidity, and excellent optical properties.

In addition, the object of the present invention is to improve the product yield, and also the high rate of warfare, since it has excellent post-processing ability, such as conveyability of the film, in the heat treatment process during post-processing such as prism lens processing, hard coat processing, and AR processing. The haze value is to provide a biaxially oriented polyester laminated film for optics that can be used throughout various optical members because of its small properties.

The above and other objects and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

The biaxially oriented polyester laminated film for optics according to the present invention for achieving the above object is based on a biaxially oriented polyester film having a thickness of 50 ~ 300㎛, a polymer layer on at least one side of the substrate, a primer layer As the formed optical film, the polymer primer layer comprises a copolyester resin, a polyurethane resin, and a polyurethane particle, silica particles or alumina-silica composite oxide particles having an average particle diameter of 50 to 300 nm, and a curing agent, The weight ratio of the copolymerized polyester resin and the polyurethane-based resin is 90:10 to 10:90, the content of the silica particles or the alumina-silica composite oxide particles is 0.01 to 60% by weight, and the content of the curing agent is 1.0 to 40% by weight. It is characterized by that.

Preferably, the surface of the base film on which the primer layer is formed is characterized in that the total light transmittance is 91% or more, the haze value is 0.4 ~ 1.0%.

Preferably, the adhesion between the base film and the primer layer is characterized in that 100% after the 96 hours humidity resistance test under 95% humidity.

Preferably, the primer layer is characterized in that it is applied after uniaxial stretching of the biaxially oriented polyester film.

Preferably, the thickness of the primer layer is characterized in that 0.05 ~ 3.00㎛.

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 biaxially oriented polyester film according to the present invention relates to a biaxially oriented polyester film excellent in adhesion and moisture resistance in a post-processing process. In the manufacturing process of the biaxially oriented polyester film, a co-polyester-based resin and a polyurethane-based resin are mixed to form a primer layer, and the easily-adhesive property of the primer layer carried out during the manufacturing process is a substrate and a post-processing polyester film. It is a biaxially-oriented polyester film which is excellent also in easily adhesive property, even after the coating process in. In addition, the film is excellent in adhesion even in the durability evaluation of high temperature and high humidity performed after the coating step.

In other words, the biaxially oriented polyester laminated film according to the present invention, unlike the conventional biaxially oriented polyester laminated film, not only easy adhesion to the substrate, but also excellent adhesion in the post-processing process, even in the evaluation of moisture resistance of high temperature and high humidity By providing an excellent function, it is a biaxially-oriented polyester film which maintains the optical characteristic which a base film has, or shows the outstanding characteristic.

It is preferable that the copolyester type resin which forms the biaxially-oriented polyester film which concerns on this invention makes a dicarboxylic acid component and the branched glycol component into a component. Branched glycol components include, for example, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-methyl-2-butyl-1,3-propanediol, 2 -Methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol, 2,2 -Diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2,2-di -n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, 2,2-di-n-hexyl-1,3-propanediol, and the like. . It is preferable to contain the branched glycol component at a rate of 10 mol% or more in the total glycol component, particularly preferably at least 20 mol%. Moreover, it is preferable to contain the branched glycol component in a ratio of 80 mol% or less in the total glycol component. If it is less than 10 mol%, there exists a tendency for the adhesiveness with a biaxially-oriented polyester film to become inadequate.

As glycol components other than the said compound, ethylene glycol is the most preferable. As small amount, diethylene glycol, propylene glycol, butanediol, hexanediol or 1,4-cyclohexanedimethanol may be used.

As the dicarboxylic acid component contained in the copolyester-based resin as a constituent, terephthalic acid and isophthalic acid are most preferred. If small amount, other dicarboxylic acid, especially diphenylcarboxylic acid and aromatic dicarboxylic acid of 2, 6- naphthalenedicarboxylic acid, may be added and copolymerized.

In addition to the dicarboxylic acid component, in order to impart water dispersibility, it is preferable to use 5-sulfoisophthalic acid in the range of 1 to 10 mol%, for example, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfo Naphthalene isophthalic acid-2,7-dicarboxylic acid, 5- (4-sulfophenoxy) isophthalic acid, its salts, etc. are mentioned.

The polyurethane resin used for the easily bonding layer of this invention can use a solvent type, a non-solvent type, or aqueous various coating agents. For example, as resin containing a block type isocyanate group, the heat-reactive type water-soluble urethane resin which blocked the terminal isocyanate group by the hydrophilic group is mentioned. Examples of the blocking agent for the isocyanate group include phenols, lactams, oximes, alcohols and active methylene compounds containing sulfonic acid groups and bisulfites.

The hardening | curing agent used for the moisture resistance improvement of this invention can be used with a solvent type and various aqueous hardening | curing agents. Although the mechanism by the said hardening | curing agent is not correct, it is thought that moisture resistance property improves by promoting reaction with the terminal group of a polyester resin and a polyurethane resin, and having excellent adhesive force with a polyester base material. For example, various oxazolines, such as 1, 4- phenylene bisoxazoline, 1, 3- phenylene bisoxazoline, and 1, 2-methoxy propanol oxazoline, etc. are mentioned.

The surfactant forming the primer layer of the biaxially oriented polyester film according to the present invention can be used in a water-soluble coating liquid, and the required amount of a known anionic or nonionic surfactant is used to increase the wettability of the base film and to uniformly apply the coating liquid. It is preferable to apply | coat to a base film.

In this invention, a primer layer is formed by apply | coating with a resin binder etc. on the film after uniaxial stretching of a biaxially-oriented polyester film. At this time, the thickness of the resin-coated layer is preferably 0.01 to 5.00 µm, more preferably 0.05 to 3.00 µm. If the thickness of the coating is thinner than 0.05㎛ the transparency is good but the adhesion is poor, if the thickness is more than 3㎛ excellent adhesion properties, but the transparency and coating properties are not preferred because it is poor.

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 inorganic particles having a relatively small difference in refractive index with the resin, thereby ensuring runability, and when the average particle diameter of the inorganic particles used is less than 30 nm, the fine particles may be Not only does not help runability and scratch resistance in the film, but also does not affect the effect of fine particle input, and when the average particle diameter of the fine particles exceeds 500 nm, there is a problem that causes haze. The size of the inorganic particles according to the present invention has a particle size in the range of 30 ~ 500nm, more preferably 50 ~ 300nm, for example, it is preferable to use silica particles or alumina-silica composite oxide particles.

In 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 total light transmittance of 91% or more, and a haze of 0.4% to 1.0%, 65 ° C, 95% humidity, and 96 hours of high temperature and high humidity conditions. It is characterized in that the adhesive strength with the base film is 100%.

Hereinafter, the present invention will be described in more detail with reference to various examples and comparative examples.

 Example 1

In Example 1, the polyester resin forming the primer layer is 4.8 wt% of a polyester resin aqueous dispersion containing 75 wt% of water and 25 wt% of a polyester resin, and the polyurethane resin is 70.0 wt% of water and a polyurethane 6.0% by weight of an aqueous dispersion containing 30.0% by weight of resin, an oxazoline-based curing agent mixed 60% by weight of water, 3.0% by weight of an aqueous dispersion containing 40% by weight of oxazoline-based curing agent, and 85.1% by weight of water, and anion 1.0% by weight of aqueous dispersion containing 90% by weight of water and 10% by weight of anionic surfactant, and 0.1% by weight of colloidal silica particles containing 70% by weight of 30% by weight of water and colloidal silica particles. A weight% was added to form a coating liquid.

In the present embodiment, the polyethylene terephthalate resin pellets were dried under reduced pressure (1.3 hPa) at 135 ° C. for 6 hours, fed to an extruder, and melt-extruded into sheets at about 280 ° C., and maintained at a surface temperature of 20 ° C. It was quenched on a metal roll to obtain a casting film having a thickness of 1925 mu m. Next, the cast film is heated to a heated roll group and an infrared heater at 100 ° C., and then stretched to a roll group having a circumferential speed with a draw ratio of 3.2 times in the longitudinal direction to obtain a uniaxially oriented PET film. Used. The coating liquid which forms the said primer layer was apply | coated to one side of the uniaxially-oriented PET film by the reverse roll method, and it dried. The coating amount (solid content weight) at this time was 0.08g / m <2>. Then, the film was gripped at the end with a clip, introduced into the hot air region, and dried. Thereafter, the film was stretched at a stretch ratio of 3.2 times in the transverse direction at 130 ° C, heat-set at 240 ° C, and laterally relaxed at 3 ° C at 200 ° C. Thus, an optical biaxially oriented polyester film having a thickness of 188 μm was obtained.

 [Example 2]

In the film formation of the biaxially oriented polyester film of Example 1, the polyester resin forming the primer layer is 2.4 wt% polyester resin aqueous dispersion containing 75 wt% water and 25 wt% polyester resin, and polyurethane resin The biaxially oriented polyester was prepared in the same manner as in Example 1 except that 8.0% by weight of an aqueous dispersion containing 70.0% by weight of water and 30.0% by weight of polyurethane-based resin were added and 85.5% by weight of water was added. The biaxially oriented polyester film for optics whose thickness of film is 188 micrometers was obtained.

Example 3

In the film formation of the biaxially oriented polyester film of Example 1, the biaxial orientation for optics was prepared after preparing the crude liquid in the same manner as in Example 1 except that the thickness of the cast film was 2200 μm and the film thickness was 250 μm after the film formation. A polyester film was obtained.

Example 4

In the film formation of the biaxially oriented polyester film of Example 1, the biaxial orientation for optics was prepared after preparing the crude liquid in the same manner as in Example 2 except that the thickness of the cast film was 2200 μm and the film thickness was 250 μm after the film formation. A polyester film was obtained.

Comparative Example 1

In the film formation of the biaxially oriented polyester film of Example 1, the polyester resin forming the primer layer is not added, but 70.0% by weight of water and 10.0% by weight of an aqueous dispersion of 30.0% by weight of the polyurethane resin are added. Except that 85.9% by weight of water was added, a crude liquid was prepared in the same manner as in Example 1, and a biaxially oriented polyester film for optics was obtained in which the biaxially oriented polyester film had a thickness of 188 μm.

 Comparative Example 2

In the film formation of the biaxially oriented polyester film of Example 1, biaxially oriented for optical after preparing a crude liquid in the same manner as in Comparative Example 1 except that the thickness of the cast film is 2200㎛, and the film thickness after film formation is 250㎛ A polyester film was obtained.

Comparative Example 3

The biaxially oriented polyester film was prepared in the same manner as in Example 1, except that the coating solution of Example 1 was prepared using 88.1% by weight of water without addition of an oxazoline-based curing agent. The biaxially oriented polyester film for phosphorus was obtained.

[Comparative Example 4]

The biaxially oriented polyester film was prepared in the same manner as in Example 1 except that the coating solution of Example 2 was prepared using 86.1% by weight of water without adding an oxazoline-based curing agent. The biaxially oriented polyester film for phosphorus was obtained.

[Comparative Example 5]

A biaxially oriented polyester film was prepared in the same manner as in Comparative Example 1 except that the coating solution of Comparative Example 1 was prepared using 84.1 wt% of water without addition of an oxazoline-based curing agent, and the thickness of the biaxially oriented polyester film was 188 μm. The biaxially oriented polyester film for phosphorus was obtained.

[Comparative Example 6]

In the film formation of the biaxially oriented polyester film of Example 1, biaxially oriented for optical after preparing a crude liquid in the same manner as in Comparative Example 3 except that the thickness of the casting film is 2200㎛, and the film thickness after film formation is 250㎛ A polyester film was obtained.

Comparative Example 7

In the film formation of the biaxially oriented polyester film of Example 1, the biaxial orientation for optics was prepared after preparing the crude liquid in the same manner as in Comparative Example 4 except that the thickness of the cast film was 2200 μm and the film thickness was 250 μm after the film formation. A polyester film was obtained.

Comparative Example 8

In the film formation of the biaxially oriented polyester film of Example 1, biaxially oriented for optical after preparing a crude liquid in the same manner as in Comparative Example 5 except that the thickness of the casting film is 2200㎛, and the film thickness after film formation is 250㎛ A polyester film was obtained.

Experimental Example 1

The coating appearance of the films prepared in Examples 1 to 4 and Comparative Examples 1 to 8 were measured. Using fluorescent light and three wavelengths of light, the coating state of the prepared coating solution was measured by visually dividing the phase into upper, middle and lower parts.

Experimental Example 2

The adhesion between the substrate and the primer layer of the film prepared in Examples 1 to 4 and Comparative Examples 1 to 8 was measured. A cellulose-based adhesive test sample was applied to the surface to which the primer layer was attached using a # 4 wire bar, and dried at 150 ° C. for 30 seconds in a drying oven. Then, a cutting line is made on the film coated with the primer layer by a cutter to place 2 mm × 2 mm squares in a 10 × 10 matrix. The cut lines are made deep enough to reach the substrate film through the adhesive layer. 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.

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

[Experimental Example 3]

The optical properties of the coating solution used in the films prepared in Examples 1 to 4 and Comparative Examples 1 to 8 were measured. Optical properties were measured by dividing the combat rate and Hz using methods commonly used in the art.

The results according to Experimental Examples 1 to 3 are shown in Table 1 below.

TABLE 1

Item Base Film Thickness (㎛) Coating liquid formulation Hardener
use
Whether coating
Exterior Haze value
(%) Light rays
Transmittance
(%) materials
Adhesive
(%) Adhesive after high temperature and high humidity
(%) Example 1 188 Polyester
Polyurethane use Prize 0.43 92.1 100 100 Example 2 188 Polyester
Polyurethane use Prize 0.62 93.1 100 100 Example 3 250 Polyester
Polyurethane use Prize O.82 92.7 100 100 Example 4 250 Polyester
Polyurethane use Prize 0.87 92.2 100 100 Comparative Example 1 188 Polyurethane use medium 0.94 93.6 80 70 Comparative Example 2 250 Polyurethane use medium 0.92 92.8 70 30 Comparative Example 3 188 Polyester
Polyurethane unused Prize 0.49 92.6 100 40 Comparative Example 4 188 Polyester
Polyurethane unused Prize 0.69 91.9 100 50 Comparative Example 5 188 Polyurethane unused medium 0.88 92.6 60 40 Comparative Example 6 250 Polyester
Polyurethane unused Prize 1.32 91.2 100 20 Comparative Example 7 250 Polyester
Polyurethane unused Prize 1.28 91.4 100 10 Comparative Example 8 250 Polyurethane unused medium 1.41 90.3 65 0

Adhesiveness after high temperature and high humidity in Table 1 shows the value measured by the method of Experimental Example 2 after the moisture resistance evaluation after 96 hours at 65 ℃, 90% humidity.

As can be seen in Table 1, the Example is superior to the coating appearance with the substrate, sufficient adhesiveness as compared to the comparative examples, as well as characteristics such as the adhesiveness required in the moisture resistance evaluation process of high temperature and high humidity. Able to know.

According to the biaxially oriented polyester film for optics according to the present invention, the primer layer used for the biaxially stretched polyester film is not only sufficient adhesiveness with the substrate, but also such as the adhesiveness required in the high temperature and high humidity resistance evaluation process. It is excellent in characteristics and excellent in optical characteristics.

In addition, the present invention can increase the product yield because it is excellent in the post-processing ability such as the conveyability of the film in the heat treatment step during post-processing such as prism lens processing, hard coat processing, AR processing and the like.

In addition, the present invention can be used throughout the various optical members because of its high combat rate and low haze value. In particular, the optical film includes a prism sheet base film, a backlight base film, and a hard coat, which are used in LCDs. There is an effect such as useful as a protective film or the like in the base film for processing and AR film and CRT.

Claims (5)

delete delete delete As an optical film which used the biaxially-oriented polyester film of thickness 50-300 micrometers as a base material, and formed the primer layer in at least one surface of the said base material as a polymer easily bonding layer, The polymer primer layer comprises a copolyester polyester resin and a polyurethane resin having a branched monomer as a component and silica particles or alumina-silica composite oxide particles having an average particle diameter of 50 to 300 nm, and a curing agent, The coating liquid for the polymer primer layer is a polyester resin water dispersion of 2.4 to 4.8% by weight containing 75% by weight of water and 25% by weight of the polyester resin as the polyester resin, 70.0% by weight of the polyurethane resin And 6.0 to 8.0% by weight of the aqueous dispersion containing 30.0% by weight of polyurethane-based resin, the oxazoline-based curing agent is 3.0% by weight of the aqueous dispersion containing 60% by weight of water and 40% by weight of the oxazoline-based curing agent, and 85.1 to 85.5 The weight percent is mixed, the anionic surfactant is 90% by weight of water and 10% by weight of the aqueous dispersion containing 10% by weight of the anionic surfactant, colloidal silica particles or alumina-silica composite oxide particles 30% by weight of water Prepared by adding 0.1 wt% of an aqueous dispersion containing 70 wt% of colloidal silica particles or alumina-silica composite oxide particles, The base film is a uniaxially orientated PET film obtained by melt-extruding polyethylene terephthalate (PET) resin pellets into a sheet to form a casting film and stretching in the longitudinal direction, The coating liquid for the polymer primer layer is applied to one side of the uniaxially oriented PET film at a coating amount (solid weight) of 0.08 g / m 2 and dried, and then stretched laterally to obtain an optical biaxially oriented polyester film. In the optical biaxially oriented polyester film, the surface of the base film on which the primer layer is formed has a total light transmittance of 91% or more, and a haze value of 0.4 to 1.0%, The adhesive force between the base film and the primer layer is 100% after a 96 hour moisture resistance test at 65 ℃, 95% humidity, optical biaxially oriented polyester film. The method of claim 4, wherein The thickness of the primer layer is characterized in that 0.05 ~ 3.00㎛, biaxially oriented polyester film.

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