KR20180119714A - Optical Polyester Film - Google Patents

Abstract

The present invention relates to a thermoplastic resin film, particularly to an optical polyester film having a primer layer formed on a polyester base film. More specifically, the present invention relates to an optical polyester film which prevents deterioration in adhesiveness due to UV pretreatment, increases productivity in a post-processing process, shows excellent humidity-resistant adhesiveness and adhesiveness with prism-processed resins as well as outstanding optical properties.

Description

Optical Polyester Film {Optical Polyester Film}

The present invention relates to an optical polyester film having a primer layer formed on a thermoplastic resin film, in particular, a polyester base film, and has a property that the adhesive force is maintained even when the primer layer is treated by UV, And an optical polyester film excellent in optical characteristics and reliability even after being processed.

Recently, a lot of changes have been made to the process in the processing of the prism sheet. Among them, in order to replace a conventional single-layer prism sheet having a thickness of 250 μm or more and a cost-saving dual-layer structure having a 125 μm prism sheet, a microlens patterning process is performed instead of a back coating process to replace a conventional diffusion sheet.

In this process change, UV is irradiated on the surface of the prism on which the prism is to be processed, in order to cure the resin to be processed on the opposite surface of the prism (the tie type is the adhesive layer and the single layer is the micro lens patterning) Is exposed to UV. This is referred to as UV pretreatment. The adhesion of the coating layer is damaged due to the UV pretreatment. In particular, in order to evaluate the reliability, problems such as an increase in the defect ratio due to the lack of adhesion after leaving in a high temperature / .

Although there is no prior art for solving the problem of the polyester film as described above, there is a TAC replacement film which blocks UV by using a UV absorber in other patent documents. However, in the case of absorbing UV itself, Layer and the microlens patterning layer, and it may adversely affect luminance because the transmittance of light of a specific wavelength band is adjusted to 10% or less. (Korean Patent Publication No. 10-2016-0091451)

Further, in the case of an invention relating to a urethane-based coating layer (polycarbonate-containing coating layer) containing 10% by weight of a polycarbonate for improving adhesion, or an invention using a crosslinking agent containing an oxazoline group for improving reliability Patent Publication No. 10-2010-0125302). However, there is no analysis of the adhesion force due to the UV pretreatment, and the technique has not yet been reported.

Accordingly, the present inventors have found that the optimum content of a hindered amine radical scavenger which inhibits UV damage, alone or in combination with a polymer mixed resin selected from the group consisting of a polyester-based polymer, a polyurethane-based polymer and an acrylic- The present inventors have completed the present invention by producing a polyester film having high adhesion and maintaining adhesion even after UV pretreatment by an in-line coating method.

Korean Patent Publication No. 10-2016-0091451 Korean Patent Publication No. 10-2012-0051043 Korean Patent Publication No. 10-2010-0125302

It is an object of the present invention to solve the problem of damaging the coating layer by UV pretreatment and deteriorating the adherence of the UV cured resin, and it is also an object of the present invention to provide a UV- An adhesive force can be ensured, an excellent reliability can be obtained, and an excellent appearance can be obtained.

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

The object is achieved by an optical film comprising a substrate film and a primer layer coated on at least one side of the base film, wherein the primer layer is coated with a coating liquid comprising a coating liquid and a hindered amine radical scavenger resin ≪ / RTI >

Here, the hindered amine radical scavenger resin preferably has 2,2,6,6, -tetramethylpiperidine skeleton.

Preferably, the hindered amine radical scavenger resin is present in an aqueous dispersion form and is contained in a proportion of 0.1 to 20% by weight based on the total solid content of the coating liquid.

Preferably, the aqueous dispersed form of the hindered amine radical scavenger resin is an aqueous dispersion containing 47% by weight of a hindered amine radical scavenger resin.

Preferably, the coating liquid is a polymer mixture resin selected from the group consisting of a water-dispersible polyester-based polymer, a urethane-based polymer, and an acrylic polymer, an oxazoline-based, carbodiimide-based, epoxy- Or a combination thereof, a surfactant, and an inorganic particle selected from the group consisting of the above-mentioned components.

Preferably, the inorganic particles are at least one of silica particles and a silica-organic compound composite, and have a refractive index of 1.5 or more and an average particle diameter of 10 to 300 nm.

Preferably, the thickness of the primer layer is 0.05 to 5 mu m.

More preferably, the adhesive force between the base film and the primer layer and the humidity resistance after 120 hours of humidity test at 65 DEG C and 95% humidity are 95% or more before and after the UV pretreatment.

According to the present invention, it is possible to suppress the deterioration of the adhesion force by the UV pretreatment, to improve the productivity in the post-processing, to have excellent adhesion with the prism processing resin, adhesion to moisture absorption, and excellent optical properties.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It will be apparent to those skilled in the art that these embodiments are provided by way of illustration only for the purpose of more particularly illustrating the present invention and that the scope of the present invention is not limited by these embodiments .

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. Also, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

An optical polyester film according to one aspect of the present invention comprises a base film and a primer layer coated on at least one side of the base film, wherein the primer layer is a coating liquid containing a coating liquid and a hindered amine radical scavenger resin Coated.

The base film is preferably a polyester film and is at least monoaxially stretched transparent polyester having a thickness of 50 to 500 mu m.

The primer layer (polymer adhesive layer) can be coated on at least one side of the base film. That is, one side or both sides.

The coating liquid in the coating liquid may be a single polymer or a mixed polymer selected from the group consisting of a water-dispersible polyester polymer containing at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group and an N-methylol group, a urethane polymer, Of resin. More preferably, it is preferably soluble or dispersible in water, and in particular, the polyurethane resin can be obtained by substitution polymerization, preferably copolymerization, of an acrylic polymer of diol.

The coating liquid may contain at least one crosslinker resin selected from the group consisting of an oxazoline series, a carbodiimide series, an epoxy series, and a melamine series to impart a normal temperature and humidity resistance. In particular, the carbodiimide-based curing agent and the oxazoline-based curing agent act to suppress the occurrence of blocking by suppressing or reacting moisture permeable to the film.

In addition, the coating liquid may contain nonionic, anionic surfactant and inorganic particles as additives. More preferably, a coating liquid comprising a binder resin and a carbodiimide-based curing agent resin and comprising a surfactant aqueous dispersion and an inorganic particle water dispersion is used.

The surfactant is for use in the aqueous coating solution of the polyester film according to the present invention and is applied to the base film using a required amount of a known anionic or nonionic surfactant to increase the wettability of the base film and uniformly coat the coating solution .

In order to improve the coating property and the function, additives can be used for the coating liquid. As such additives, organic particles, inorganic particles, defoaming agents and the like can be used. According to the present invention, inorganic particles are contained in the primer layer to ensure running properties. However, when the average particle size exceeds 500 nm, there arises a problem that the haze increases. Accordingly, the size of the inorganic particles used in the present invention preferably has a particle size in the range of 10 to 300 nm. The inorganic particles are preferably at least one of silica particles and a silica-organic compound composite having a refractive index of 1.5 or more.

In addition, the coating liquid includes a hindered amine-based radical scavenging water dispersion to suppress the damage of the primer layer by the UV pre-treatment. The hindered amine radical scavenger resin reacts with generated radicals to inhibit additional radical reactions and to inhibit damage to the primer layer by UV pretreatment. These hindered amine radical scavengers have 2,2,6,6, -tetramethylperperidine skeleton and are known to be highly reliable materials such as heat resistance and long-term weatherability. In addition, products derived from ADEKA or BASF, .

The hindered amine radical scavenger resin is preferably present in an aqueous dispersion form and is preferably contained in a proportion of 0.1 to 20% by weight, more preferably 3 to 10% by weight, based on the total solid content of the coating liquid. . In addition, the water dispersion type of the hindered amine radical scavenger resin is an aqueous dispersion containing a hindered amine radical scavenger resin of 47% by weight. When the amount of the hindered amine radical scavenger resin is less than 0.1% by weight based on the total solid content of the coating liquid, there is a disadvantage in that the adhesion of moisture resistance after UV pretreatment is deteriorated. When the amount exceeds 20% by weight, coating properties and transparency This is because there are drawbacks.

The thickness of the primer layer (coating layer) coated with the above-described coating liquid is preferably 0.05 to 5 占 퐉, more preferably 0.05 to 3 占 퐉. If the thickness is thinner than 0.05 탆, the transparency becomes good, but the adhesive force decreases in the post-processing. If it is thicker than 5 탆, the adhesion property is excellent, but transparency and coating property are deteriorated.

The optical polyester film according to the present invention has a total light transmittance of 90% or more and a haze of 1.5% or less, and has an adhesion force between the base film and the primer layer and a humidity resistance test at 65 ° C and 95% The adhesion is characterized by 95% or more both before and after the UV pretreatment.

Hereinafter, the structure and effect of the present invention will be described in more detail with reference to examples and comparative examples. However, this embodiment is intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

[Example]

Use liquid

Polyurethane resin: H-15 (JEOL Co., Ltd., Japan)

Carbodiimide resin: SV-02 (Nissin Bosa, Japan)

Hindered amine radical scavenger resin: UC-606 (radical scavenger resin having tetramethylpiperidine skeleton, 2,2,6,6, ADEKA, Japan)

≪ Examples 1 to 5 >

20.0% by weight of a binder resin aqueous dispersion of 70% by weight of water and 30% by weight of a polyurethane resin, 40% by weight of a carbodiimide-based curing agent as a curing agent for improving the curing density, 5% by weight of an aqueous dispersion was mixed, and 1.0% by weight of a surfactant aqueous dispersion composed of 90% by weight of water and 10% by weight of an anionic surfactant, 0.5% by weight of a silica particle water dispersion comprising 70% by weight of silica particles and 30% %, And residual water to prepare a coating liquid. Hardened amine radical scavenger resin 47 weight (weight ratio) was added to the total solid content of the coating liquid at a ratio of 0.1, 3, 5, 10 and 20 wt% % And 53% by weight of water was added to prepare a coating solution. Thereafter, the film was applied in a line to a monoaxially stretched polyester base film having a thickness of 100 占 퐉 in-line to produce an optical polyester film. # 4 wire bar.

≪ Comparative Example 1 &

20.0% by weight of a binder resin aqueous dispersion of 70% by weight of water and 30% by weight of a polyurethane resin, 40% by weight of a carbodiimide-based curing agent as a curing agent for improving the curing density, 5% by weight aqueous dispersion, 1.0% by weight of a surfactant aqueous dispersion composed of 90% by weight of water and 10% by weight of an anionic surfactant, 0.5% by weight of a silica particle water dispersion comprising 70% by weight of silica particles and 30% % And a residual amount of water. Thereafter, the film was applied in a line to a monoaxially stretched polyester base film having a thickness of 100 占 퐉 in-line to produce an optical polyester film. # 4 wire bar.

≪ Comparative Examples 2 and 3 >

20.0% by weight of a binder resin aqueous dispersion of 70% by weight of water and 30% by weight of a polyurethane resin, 40% by weight of a carbodiimide-based curing agent as a curing agent for improving the curing density, 5% by weight aqueous dispersion, 1.0% by weight of a surfactant aqueous dispersion composed of 90% by weight of water and 10% by weight of an anionic surfactant, 0.5% by weight of a silica particle water dispersion comprising 70% by weight of silica particles and 30% % And a residual amount of water was used to prepare a coating liquid. Then, the coating liquid was coated with a hindered amine radical scavenger resin in an amount of 0.05 wt% and 25 wt% And 53% by weight of water were added to prepare a coating solution. Thereafter, the film was applied in a line to a monoaxially stretched polyester base film having a thickness of 100 占 퐉 in-line to produce an optical polyester film. # 4 wire bar.

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

[Experimental Example]

1. Confirm adhesion

An acrylic UV curable resin was applied to the coated layers of the films prepared in Examples 1 to 5 and Comparative Examples 1 to 3 using a # 20 wire bar, and the adhesion between the coated layer and the UV resin was measured. Adhesion is created by cutting lines on film coated with a cutter, placing 2 mm by 2 mm squares on a 10 x 10 matrix. Attach a cellophane tape (No. 405, made by NICHIBAN: 24 mm) to the film with the cut line, rub the tape with a velvet, attach it strongly to the film, and remove the tape vertically. The area of the UV resin remaining on the coating layer was visually observed and the adhesion was calculated by the following equation (1).

(1)

Adhesion (%) = (1 - Defective area / Evaluation area) * 100

2. Evaluation of adhesion of moisture

The adhesive force after 120 hours at 65 ° C and 95% humidity was performed in the same manner as in the above adhesion test.

3. Check coating property

In Examples 1 to 5 and Comparative Examples 1 to 3, the coating properties between the coating liquid as the coating layer and the substrate were measured. # 0 to # 6 Apply the coating layer to the substrate using a wire bar to check whether the entire surface of the substrate is coated with the coating layer. It was evaluated that the coatings were excellent when there were no more than 2 parts in 100 small square reference (1 square: 1 x 1 mm), where no coating solution was observed like an island.

4. UV pretreatment

The coating layers of the films prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to UV pre-treatment to compare their adhesion. UV pretreatment and curing of UV resin were controlled by using a small UV curing machine at a light intensity of 500 mJ.

5. Confirm Haze / light transmittance

The coating liquid prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was applied to a PET film of 188 탆 and thermally cured, and haze and transmittance were measured using a HAZE measuring instrument (NDH 4000) manufactured by NIPPON DENSHOKU .

division Radical scavenger input
(weight%) Adhesion (%) Humidity Adhesion (%) Coating property Haze /
Light transmittance
(%) UV pretreatment UV pretreatment none 1 time none 1 time Example 1 0.1 100 100 100 98 O 0.28 /
92.9 Example 2 3 100 100 100 100 O 0.32
/ 91.4 Example 3 5 100 100 100 100 O 0.48 /
91.0 Example 4 10 100 100 100 100 O 0.54 /
90.9 Example 5 20 100 100 100 95 O 0.68 /
90.1 Comparative Example 1 0 100 32 100 10 O 0.27 /
88.4 Comparative Example 2 0.05 100 91 100 82 O 0.38 /
93.2 Comparative Example 3 25 100 100 100 100 X 1.1 /
88.4

As can be seen from Table 1, according to the optical polyester film according to the embodiment of the present invention, when an appropriate amount of hindered amine radical scavenger is used in the optical film, the adhesive force and the adhesion of the humidity resistance are excellent even before and after the UV pretreatment can confirm. It is also understood that it is possible to produce a film having excellent physical properties such as coating properties and transparency required for optical films.

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.

Claims (8)

A base film,
And a fryer layer coated on at least one side of the base film,
Wherein the primer layer is coated with a coating liquid containing a coating liquid and a hindered amine radical scavenger resin. The method according to claim 1,
Wherein the hindered amine radical scavenger resin has a 2,2,6,6-tetramethylpiperidine skeleton. The method according to claim 1,
The hindered amine radical scavenger resin is present in an aqueous dispersion form and is contained in an amount of 0.1 to 20% by weight based on the total solid content of the coating liquid. The method of claim 3,
Wherein the water dispersion type of the hindered amine radical scavenger resin is an aqueous dispersion containing a hindered amine radical scavenger resin of 47% by weight. The method according to claim 1,
The coating liquid may be selected from the group consisting of a water-dispersible polyester-based polymer, a urethane-based polymer, and an acrylic polymer, or a polymer mixed resin thereof, oxazoline-based, carbodiimide-based, epoxy-based or melamine-based Or a combination thereof, a surfactant, and an inorganic particle. 6. The method of claim 5,
Wherein the inorganic particles are at least one of silica particles and a silica-organic composite, and the refractive index is 1.5 or more and the average particle diameter is 10 to 300 nm. The method according to claim 1,
Wherein the primer layer has a thickness of 0.05 to 5 占 퐉. 8. The method according to any one of claims 1 to 7,
Wherein the adhesive force between the base film and the primer layer and the moisture resistance adhering force after the moisture resistance test at 65 ° C and 95% humidity for 120 hours are 95% or more before and after the UV pretreatment.