KR20140091814A - Optical polyester film with excellent anti-blocking property - Google Patents

Abstract

The present invention relates to an optical polyester film having excellent anti-blocking property and, more specifically, to an optical polyester film having excellent anti-blocking property which has excellent adhesion, moistureproof adhesion, and optical characteristics such as transmissivity, haze characteristics, etc. and is capable of preventing a blocking phenomenon which refers to adhesion occurring among coating layers by moisture permeation or by the combination between unreactive molecules in a coating layer. The optical polyester film having excellent anti-blocking property according to the present invention comprises a primer layer formed by coating a coating solution on at least one surface of a polyester base film, the coating solution containing polyurethane resin, an isocyanate hardener, an oxazoline hardener, a surfactant and an aqueous dispersion of particles.

Description

(OPTICAL POLYESTER FILM WITH EXCELLENT ANTI-BLOCKING PROPERTY)

The present invention relates to an optical polyester film having excellent blocking resistance, and more particularly to a polyester film for optical use which is excellent in adhesion and adhesion of moisture absorption, has excellent optical properties such as transmittance and haze, To an optical polyester film excellent in blocking resistance capable of preventing a blocking phenomenon in which coating layers are adhered to each other.

In general, as the functional polymer substrate, there are polyester based substrates such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polycarbonate (PC), and they are excellent in dimensional stability, thickness uniformity and optical transparency, It is widely used for various industrial materials as well as devices.

Particularly, since a primer layer is formed on a polyester base film in optical polyester base materials, a copolymer polyester base resin having excellent adhesion with a polyester base material is mainly used as a component of the primer layer. In general, The adhesion between the polymer base film and the primer layer is excellent.

As a conventional polyester film for optical use, Korean Patent Laid-Open Publication No. 2011-7030558 discloses "a polyester film having an adhesive layer having a coating layer containing a polyester resin and particles A and B, Wherein the polyester resin comprises a naphthalene dicarboxylic acid, a dicarboxylic acid component and / or a diol component as an acid component and the particle A is a metal oxide particle having a refractive index of 1.7 or more and 3.0 or less, And the particle B is particles having an average particle diameter of 200 nm or more and 700 nm or less ", and in Korean Patent Laid-Open Publication No. 2009-0104594," polyester having a refractive index of 1.6 to 1.7 Film and a coating layer having a refractive index of 1.4 to 1.6 on both sides of the polyester film, wherein the refractive index difference between the polyester film and the coating layer is 0.1 or more, Group and a thickness of 0.03 ~ 0.1㎛ of each coating layer and having a total light transmittance of the entire film 93% or more, and a total light transmittance of the coating layer is at least 3% more optical polyester film "with respect to the free polyester film, each substrate.

In addition, in the case of the optical polyester film, not only the high optical properties but also the adhesion force between the polyester substrate and the optical functional layer and the blocking phenomenon due to the penetration of moisture or the unreacted molecules of the coating layer are inhibited And the wide range of polyester films developed to date do not sufficiently satisfy the requirements.

Thus, the present inventors have found that when a coating layer comprising a polyurethane resin, an isocyanate curing agent, an oxazoline curing agent, and a surfactant and particles is formed, the adhesion and adhesion of the polyester base and the optical functional layer are excellent, An optical polyester film having excellent optical properties with a haze of 1.5% or less and improved blocking properties was completed.

Korean Patent Publication No. 2011-7030558 Korean Patent Publication No. 2009-0104594

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a water- And an object of the present invention is to provide an optical polyester film excellent in blocking resistance that can prevent a blocking phenomenon in which coating layers are bonded together.

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

This object is achieved by a primer layer formed by coating a coating liquid containing at least one surface of a polyester base film with a coating liquid containing a polyurethane resin, an isocyanate curing agent, an oxazoline curing agent, a surfactant, Is achieved by this excellent optical polyester film.

Here, the coating liquid is prepared by mixing 10 to 30 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt%, 10 to 50 parts by weight of an isocyanate curing agent aqueous dispersion having a solid content of 20 wt% 1 to 5 parts by weight of an anionic surfactant aqueous dispersion having a solid content of 10 wt% and 0.1 to 10 parts by weight of a silica particle or alumina-silica composite oxide particle aqueous dispersion having a solid content of 70 wt% of silica particles or alumina- .

Preferably, the weight ratio of the oxazoline curing agent aqueous dispersion to the isocyanate curing agent aqueous dispersion is 1 to 2: 1.

Preferably, the average particle diameter of the silica particles or alumina-silica composite oxide particles of the silica particle or alumina-silica composite oxide particle dispersion is 20 nm to 500 nm.

Preferably, the thickness of the primer layer is 0.05 탆 to 3 탆.

Preferably, the optical polyester film excellent in blocking resistance has a transmittance of 85% or more and a haze of less than 1.5%.

According to the present invention, it is possible to prevent the blocking phenomenon in which the adhesion between the coating layers due to the penetration of water or the bonding between the unreacted molecules in the coating layer is prevented Effect.

Hereinafter, the present invention will be described in detail with reference to examples 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 .

The optical polyester film excellent in blocking resistance according to the present invention is a polyester film obtained by applying a coating liquid containing a polyurethane resin, an isocyanate curing agent, an oxazoline curing agent, a surfactant and a grain control solution to at least one surface of a polyester base film, Layer. ≪ / RTI >

In the present invention, the primer layer is formed on one side or both sides of an optical polyester base film, and exhibits excellent adhesion (easy adhesion) to facilitate adhesion to other substrates.

More specifically, the coating liquid contains 10 to 30 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt%, 10 to 50 wt% of an isocyanate curing agent aqueous dispersion having a solid content of 20 wt% 1 to 5 parts by weight of an anionic surfactant aqueous dispersion having a solid content of 10 wt% and a silica particle or alumina-silica composite oxide particle dispersion having a solid content of 70 wt% of silica particles or alumina-silica composite oxide particles of 0.1 to 10 wt% And the like.

The polyester base film used in the present invention is a high functional polymer base material having excellent dimensional stability, thickness uniformity and optical transparency, and its use is not particularly limited, but examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN) It is preferable to use a polyester-based substrate such as carbonate (PC).

The oxazoline curing agent, which is used as a crosslinking agent in the coating liquid, has good reactivity with the polyester base material itself and helps adhesion between the polyester base material and the primer layer. In addition, it is possible to improve the durability of the primer layer by forming a strong network (crosslinking) by easily bonding with the urethane resin and the oxazoline curing agent which are widely used as the primer layer in the industry, and improving dispersibility and reactivity for environmentally friendly water- It is preferable that the polymer is applied in the form of a crosslinking agent or a curing agent having an oxazoline bonded to a polymer functional group. And the content thereof is preferably 10 to 30 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% with respect to 100 parts by weight of the polyurethane resin water dispersion. If the content is less than 10 parts by weight, the content thereof is insufficient, and the resin network (crosslinking) of the primer layer and the adhesive force with the polyester base material are insufficient, whereby the durability and the moisture resistance are lowered and the object of the present invention can not be achieved When the content is more than 30 parts by weight, it is difficult to store the polyester based materials when they are applied on both sides due to the reactivity of oxazoline capable of reacting at room temperature, and oxazoline functional groups are present in unreacted state, Which is undesirable.

The isocyanate curing agent in the coating liquid is preferably a heat-responsive water-soluble polyisocyanate curing agent and is preferably contained in an amount of 10 to 50 parts by weight of an isocyanate curing agent aqueous dispersion having a solid content of 20 wt% with respect to 100 parts by weight of the polyurethane resin aqueous dispersion. If the content is less than 10 parts by weight, the thickness of the primer layer becomes too thin. If the content is more than 50 parts by weight, there is a problem that a large amount of defects occur when the coating is applied to a polyester base material.

Urethane resin in the coating liquid is excellent in adhesion, but has a good adhesion between urethane. Therefore, when a two-side coating is performed, there is a high possibility that water penetration and bonding of unreacted molecules cause adhesion of both surfaces of urethane, that is, blocking. Therefore, by adding the polyisocyanate curing agent, phase separation occurs in the coating layer, so that the oxazoline curing agent is positioned on the surface of the coating layer and the urethane is positioned on the polyester base side, thereby inhibiting the blocking phenomenon.

The coating liquid according to the present invention is characterized in that the weight ratio of the oxazoline curing agent aqueous dispersion to the isocyanate curing agent aqueous dispersion is 1 to 2: 1. When the oxazoline curing agent is added in excess of the weight ratio of 1 to 2: 1 by weight of the oxazoline curing agent aqueous dispersion and the aqueous dispersion of the isocyanate curing agent, the adherence is lowered due to the remaining oxazoline curing agent not participating in the reaction, When the amount of the zolene curing agent is less than the above-mentioned weight ratio (when an excess amount of the isocyanate curing agent is added), the blocking property is lowered and the object of the present invention can not be achieved.

The water-dispersible coating liquid can be used as an additive because of coating properties of the polyester-based polymer base and heat-resistant processing on the primer layer, and organic particles, inorganic particles and defoaming agent for the polyester- have. In this case, in the case of inorganic particles, silica particles or alumina-silica composite oxide particles are preferably used. The reason for using the inorganic particles is that when the inorganic particles containing the inorganic particles having a relatively small difference in refractive index from the constituent resin of the water dispersion coating liquid are contained, the running ability can be accelerated and the production amount can be ensured. The average particle size of the inorganic particles is 20 nm or more and 500 nm or less, Or more and 300 nm or less. When the average particle size of the inorganic particles is less than 20 nm, the fine particles are lower in thickness than the primer layer in the case of using the automation system, so that they do not contribute to the running property and the scratch resistance and the effect of the fine particles can not be expected. If the average particle diameter exceeds 500 nm, the haze is poor, which is not preferable.

The silica particles or the alumina-silica composite oxide particles preferably contain silica particles or alumina-silica composite oxide particles in an amount of from 0.1 to 10 parts by weight of a silica particle or alumina-silica composite oxide particle dispersion having a solid content of 70 wt% If the content of the particles is less than 0.1 part by weight, it does not greatly contribute to the running property. If the content exceeds 10 parts by weight, the turbidity of the product increases and the film becomes opaque.

Furthermore, in the case of using the heat-reactive water-soluble polyisocyanate resin in the resin, 0.1 to 10 parts by weight of tin catalyst may be further added to make mono-molecular isocyanate into polyisocyanate. So that polymerization is performed well.

The aqueous dispersion coating solution may further contain a surfactant dispersed for water-based coating. In order to increase the wettability of the optical polyester base film and uniformly coat the aqueous dispersion coating solution, a known anionic or nonionic surfactant Can be applied on a substrate. And preferably 1 to 5 parts by weight of an anionic surfactant aqueous dispersion having a solid content of 10% by weight.

The thickness of the primer layer formed by applying the above water dispersion coating solution on the optical polymer base film is preferably 0.05 탆 or more and 3 탆 or less, and when the thickness of the primer layer is less than 0.05 탆, transparency is good, When the thickness exceeds 3 탆, the adhesive property is excellent but the transparency and coating property are deteriorated.

In addition, the adhesive strength of the polymer base material is calculated by the number of distant matrices in a 2 x 2 mm square formed on a 10 x 10 matrix formed by cutting lines with a cross cutter, and the adhesive strength between 60 ° C and 70 ° C and 90% The adhesive property of the optical polymer base material film and the primer layer is 100% even after boiling the film for 10 minutes in boiling water after the high temperature and high humidity treatment for 96 hours at 65 ° C and 95% humidity, %, Showing excellent moisture resistance.

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 1]

100 parts by weight of a polyurethane resin water dispersion having a solid content of 20 wt%, 14.3 parts by weight of an oxazoline curing agent water dispersion having a solid content of 25 wt%, and 14.3 parts by weight of an isocyanate curing agent water dispersion having a solid content of 20 wt% (an oxazoline curing agent aqueous dispersion and an isocyanate curing agent 1.43 parts by weight of an anionic surfactant aqueous dispersion having a solid content of 10 wt%, and 1.43 parts by weight of a colloidal silica particle aqueous dispersion having a solid content of 70 wt% of a solid content of colloidal silica particles were mixed to prepare a water dispersion coating solution . The above-prepared water dispersion coating solution was applied to a polyester film having a thickness of 188 탆 to prepare an optical polyester film having a primer layer.

EPOCROS WS500 manufactured by Nihon Shokubai Co., Ltd. was used as the oxazoline curing agent, which is an oxazoline group-containing curing agent used in Example 1, and isocyanate curing agent, manufactured by Baxenden Chemical Co., Ltd., which is blocked with DMP (3,5-dimethyl pyrazole) "BI-7986" was used.

[Example 2]

Dispersed solution of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% were mixed to prepare a water dispersion coating liquid at a weight ratio of oxazoline curing agent aqueous dispersion to isocyanate curing agent aqueous dispersion of 2: 1. To prepare an optical polyester film.

[Example 3]

Dispersed solution of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% were mixed to prepare a water dispersion coating solution having a weight ratio of an oxazoline curing agent aqueous dispersion and an isocyanate curing agent aqueous dispersion adjusted to 1.5: 1. To prepare an optical polyester film.

[Comparative Example 1]

100 parts by weight of a polyurethane resin aqueous dispersion having a solid content of 20 wt%, 28.6 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt%, 4.29 parts by weight of an anionic surfactant aqueous dispersion having a solid content of 10 wt%, a solid content of colloidal silica particles And 1.43 parts by weight of the 70 wt% colloidal silica particle aqueous dispersion were mixed to prepare a water dispersion coating solution. The above-prepared water dispersion coating solution was applied to a polyester film having a thickness of 188 탆 to prepare an optical polyester film having a primer layer.

The oxazoline curing agent used as the curing agent having an oxazoline group used in Comparative Example 1 was "EPOCROS WS500" manufactured by Nippon Shokubai Co., Ltd.

[Comparative Example 2]

And 42.9 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% were mixed to prepare a water dispersion coating solution, to thereby produce an optical polyester film having a primer layer.

[Comparative Example 3]

And 71.5 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% were mixed to prepare a water dispersion coating solution, to thereby prepare an optical polyester film having a primer layer.

[Comparative Example 4]

And 100 parts by weight of an aqueous dispersion of an oxazoline curing agent having a solid content of 25 wt% were mixed to prepare a water dispersion coating solution, an optical polyester film having a primer layer was prepared.

[Comparative Example 5]

And 35.75 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% were mixed to prepare a water dispersion coating liquid having a weight ratio of 2.5: 1 by weight of the oxazoline curing agent aqueous dispersion to the isocyanate curing agent aqueous dispersion, To prepare an optical polyester film.

[Comparative Example 6]

And a water dispersion of an oxazoline curing agent aqueous dispersion having a solid content of 25 wt% were mixed to prepare a water dispersion coating liquid at a weight ratio of the oxazoline curing agent aqueous dispersion to the isocyanate curing agent aqueous dispersion of 0.5: 1. To prepare an optical polyester film.

The properties of the optical polyester films according to Examples 1 to 3 and Comparative Examples 1 to 4 were measured through the following experimental examples, and the results are shown in Table 1 below.

[Experimental Example 1] Adhesive force measurement

Using a wire bar (# 8), an acrylic UV curable resin was applied to the surface on which the primer layer was formed, and a cut line was formed on a substrate coated with a primer layer with a cross cutter. Mm squares. The tape was rubbed and attached strongly to the film using a velvet, and then the tape was vertically peeled off to remove the adhesive layer (not shown) on the substrate. The area of the remaining primer layer was visually observed, and the adhesion was calculated by the following equation (1).

(1)

Adhesive force (%) = (100-removed number) (%)

[Experimental Example 2] Measurement of adhesion of humidity

An acrylic UV curable resin was applied to the surface on which the primer layer was formed using a wire bar (# 8), followed by heat treatment in boiling water for 10 minutes, and then cut lines were formed on the substrate coated with the primer layer by a cutter, 10 mm square with 2 mm x 2 mm square. The tape was rubbed and attached strongly to the film using a velvet, and then the tape was vertically peeled off to remove the adhesive layer (not shown) on the substrate. The area of the remaining primer layer was visually observed, and the adhesive force was calculated by the above-mentioned formula (1).

[Experimental Example 3] Measurement of blocking property

In the polyester film produced according to the above example, the coating layers are brought into contact with each other so as to face each other, and then the sample is formed by winding it in the smallest possible diameter and fixing it with tape. The sample was placed in a thermo-hygrostat at 85 ° C and 85% humidity for 3 days, and then the tape was removed and spread to confirm adhesion of the coating layers.

division Adhesion Humidity adhesion blocking Example 1
(Oxa: BI = 1: 1) 100 100 about Example 2
(Oxa: BI = 2: 1) 100 100 weak Example 3
(Oxa: BI = 1.5: 1) 100 100 Generation X Comparative Example 1 90 70 medium Comparative Example 2 85 60 River Comparative Example 3 80 55 River Comparative Example 4 50 20 River Comparative Example 5
(Oxa: BI = 2.5: 1) 87 75 about Comparative Example 6
(Oxa: BI = 0.5: 1) 95 90 River

As shown in Table 1 above, the optical polyester film having excellent blocking resistance according to the present invention was obtained by adjusting the ratio of the oxazoline curing agent to the isocyanate curing agent to obtain an optical polyester film having excellent adhesion and moisture- Can be obtained. Further, when the oxazoline curing agent was added in an excessive amount in Comparative Example 5, the adhesion was decreased due to the influence of the residual oxazoline curing agent not participating in the reaction. Conversely, when a small amount of the oxazoline curing agent was added in Comparative Example 6, It can be confirmed that the object of the invention can not be achieved.

INDUSTRIAL APPLICABILITY As described above, the present invention is characterized in that a carboxylate and an oxazoline of a urethane resin are easily bonded to each other by forming a primer layer by applying a water dispersion coating solution containing an isocyanate curing agent and an oxazoline curing agent as a crosslinking agent on a polyester base film Even when an optical functional layer such as a prism lens processing or a lenticular processing is added on the primer layer due to the establishment of a strong network, not only the adhesion to the optical functional layer but also the adhesion between the optical polyester base film and the primer layer is excellent , Excellent adhesion with the polyester base film is maintained even under the conditions of high temperature and high humidity, and moisture resistance is excellent, and optical characteristics of 1.5% or less in haze and 85% or more in transmittance of 85% or more can be used throughout the various optical members, By penetration and bonding of unreacted molecules in the coating layer, It may provide an optical polyester film which can suppress blocking of the adhesive takes place.

Therefore, when an optical functional layer such as a prism or a light-diffusing layer is formed on an optical polyester film having excellent blocking resistance according to the present invention, the adhesive force between the polyester film base and the optical functional layer and the moisture- And haze can be prevented and blocking phenomenon in which the coating layers are adhered to each other due to moisture penetration or bonding between unreacted molecules in the coating layer can be prevented and the optical polyester film having excellent anti- It can be seen that the enemy value is very high.

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 (6)

In an optical polyester film excellent in blocking resistance,
A primer layer formed by applying a coating liquid containing at least one surface of a polyester base film to a coating liquid containing a polyurethane resin, an isocyanate curing agent, an oxazoline curing agent, a surfactant and a grain control liquid. Polyester film. The method according to claim 1,
The coating liquid contains 10 to 30 parts by weight of an oxazoline curing agent aqueous dispersion having a solid content of 25% by weight, 10 to 50 parts by weight of an isocyanate curing agent aqueous dispersion having a solid content of 20% by weight, 1 to 5 parts by weight of an anionic surfactant aqueous dispersion having a content of 10 wt% and 0.1 to 10 parts by weight of a silica particle or an alumina-silica composite oxide particle aqueous dispersion having a solid content of 70% by weight of silica particles or alumina-silica composite oxide particles Wherein the polyester film has an excellent anti-blocking property. 3. The method of claim 2,
Wherein the weight ratio of the oxazoline curing agent aqueous dispersion to the isocyanate curing agent aqueous dispersion is 1 to 2: 1. The method of claim 3,
Wherein the average particle diameter of the silica particles or the alumina-silica composite oxide particles in the silica particle or alumina-silica composite oxide particle aqueous dispersion is from 20 nm to 500 nm. The method according to claim 1,
Wherein the primer layer has a thickness of 0.05 탆 to 3 탆. 6. The method according to any one of claims 1 to 5,
The optical polyester film excellent in blocking resistance is characterized by having a transmittance of 85% or more and a haze of less than 1.5%.