KR20100081568A - Biaxially-oriented polyester adhesive film for improvingsurface hardness - Google Patents

Abstract

PURPOSE: A biaxially oriented polyester adhesive film is provided to have enough adhesive force of a primer layer with a substrate and to obtain excellent surface hardness and scratch resistance by improving wet-proof property and hardness at a high temperature and high humidity. CONSTITUTION: A biaxially oriented polyester adhesive film comprises a base film and a primer layer used as a polymer adhesive layer. The primer layer is coated with a water-soluble urethane resin which is thermally reacted and is comprised of an isocyanate group having both ends blocked with bisulfate, a thermally reactive resin including a hydroxyl group, an acetate group, an alkoxy group, a carbodiimide group, or a nucleophilic reactive group, a silica particle or an alumina-silica complex oxide particle, an anionic surfactant, a pH adjusting agent of an alkali component, and a coating solution including water.

Description

Biaxially Oriented POLYESTER ADHESIVE FILM FOR IMPROVINGSURFACE HARDNESS}

The present invention relates to an optical biaxially oriented polyester easy-adhesive film having a surface hardness enhancement function, and more particularly, a primer layer used for a biaxially stretched polyester film is not only sufficient adhesiveness with a substrate but also under high temperature and high humidity. Optical biaxially oriented polyester which has excellent surface hardness and scratch resistance by improving moisture resistance and hardenability, and has excellent surface hardness improvement such as coating appearance, heat shrinkage and optical properties with substrate. It relates to an adhesive film.

Recently, as interest in liquid crystal displays, organic light emitting diode displays, and electronic papers has increased rapidly, studies are being actively conducted to replace the substrates of these display devices with polyester films instead of glass substrates. In other words, replacing the glass substrate with a polyester film may reduce the overall weight of the display device and provide design flexibility, and may be economically resistant to impact when it is manufactured in a continuous process.

Meanwhile, in order to be used as a polyester film of a display device, characteristics such as high glass transition temperature, high light transmittance and surface scratch resistance that can withstand the deposition temperature of the transparent electrode are required.

Many conventional polyester films undergo a process of coating a hard coat layer on the surface, and a problem in manufacturing such a structure is that deformation and crack of the polyester film due to large difference in coefficient of linear expansion between the polyester film and the hard coat layer And peeling may occur. Therefore, it can be said that the adhesion between the coating layer and the design of the appropriate structure to minimize the stress at the interface of each layer is very important.

In addition, when the biaxially oriented polyester film is used as the base film, it has advantages such as high light transmittance and surface flatness, but is weak in impact and has a disadvantage in that deformation at a predetermined temperature or more occurs. In particular, when the primer layer is higher than the glass transition temperature of the polyester, there is a problem of their thermal stability and susceptibility to hydrolysis. The susceptibility to hydrolysis here is a characteristic of the hydrolytically degraded polyester in a humid environment, for example it can be identified by a decrease in IV or SV value (viscosity, viscosity). The susceptibility to hydrolysis is particularly judged not only by aliphatic polyesters but also by aromatic polyesters such as PBT and PET. If the susceptibility to hydrolysis of PET is too large for the application, it may be necessary to rely on more hydrolytically resistant PEN or other polymers such as polyetherimide or polyimide. However, they are significantly more expensive than PET and are therefore not suitable for economic reasons. For this reason, there have been attempts to improve the hydrolysis resistance of polyester films through mixing of hydrolysis stabilizers or thermally reactive resins.

The present invention has been made to solve the above problems, the object of the present invention is a primer layer used in a biaxially stretched polyester film, as well as sufficient adhesiveness with the substrate, moisture resistance function and degree of curing under high temperature and high humidity It is an object of the present invention to provide an optical biaxially oriented polyester easy-adhesive film having excellent surface hardness enhancement functions such as excellent surface hardness and scratch resistance due to improvement and excellent optical properties.

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 to form a biaxially oriented polyester film having a thickness of 50 ~ 300㎛ base film and a primer layer as a polymer adhesive layer on at least one side of the base film, the primer layer is blocked with bisulfite at both ends A thermally reactive water-soluble urethane resin composed of an isocyanate group, a thermally reactive resin including a hydroxyl group, an acetate group, an alkoxy group, a carbodiimide group or a nucleophilic reactor such as epoxy, oxetane, and aziridine in the polymer chain, A coating liquid comprising a catalyst, silica particles or alumina-silica composite oxide particles having an average particle diameter of 50 to 300 nm, an anionic surfactant, a pH regulator of an alkaline component, and water, and the coating liquid is the thermally reactive water-soluble type. Urethane resin is a heat-reactive water-soluble urethane water containing 20% by weight of heat-reactive water-soluble urethane resin 1.0 to 10.0% by weight of the aqueous dispersion, 1.0 to 5.0% by weight of the thermal reaction resin aqueous dispersion containing 40% by weight of the thermal reaction resin, the tin-based catalyst 10% by weight of the tin-based catalyst 0.1 wt% to 1.0 wt% tin-based catalyst aqueous dispersion, and the silica particles or alumina-silica composite oxide particles include silica particles or alumina-silica composite oxide particles containing 0.1 wt% of silica particles or alumina-silica composite oxide particles. 1.0% by weight, the anionic surfactant is 0.1 to 1.0% by weight of an aqueous dispersion of anionic surfactant containing 10% by weight of anionic surfactant, the pH adjusting agent comprises 0.5 to 2.0% by weight of the pH regulator and the balance of water It is achieved by an optical biaxially oriented polyester easy-adhesive film having a surface hardness enhancement function.

Here, the pH adjusting agent is characterized in that sodium hydrogen carbonate.

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 ~ 1.0%.

Preferably, the adhesion between the base film and the primer layer is characterized in that 100% after a 96 hours moisture resistance test at 65 ℃, 95% humidity.

Preferably, the pencil hardness between the base film and the primer layer is characterized in that 1H or more.

Preferably, the heat shrink between the base film and the primer layer is characterized in that less than 0.8 in the TD and MD direction.

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㎛.

According to the present invention, the primer layer used in the biaxially stretched polyester film has not only sufficient adhesiveness with the substrate but also excellent properties such as surface hardness and scratch resistance due to improved moisture resistance function and hardenability under high temperature and high humidity. The optical properties such as coating appearance with the substrate, heat shrinkage and optical properties are excellent.

In addition, the present invention is excellent in post-processing ability such as conveyability of the film in the heat treatment step during post-processing such as prism lens processing, hard coat processing, AR processing, etc., so that the product yield can be increased.

In addition, the present invention can be used throughout the various optical members due to its high combat rate and low haze value. Especially, as an optical film, a base film for prism sheet, a base film for backlight, hard It is effective in coating processing, base film for AR film, and CRT, and the like as a protective film.

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. .

1 is a cross-sectional view of an optical biaxially oriented polyester adhesive film having a surface hardness improving function according to the present invention.

Optical biaxially oriented polyester easy-adhesive film having a surface hardness improving function according to the present invention relates to a biaxially oriented polyester film excellent in adhesion and moisture resistance in the post-processing process, both ends during the manufacturing process of the biaxially oriented polyester film A primer layer is formed by mixing a heat-reactive water-soluble urethane resin and a heat-reactive resin made of an isocyanate group blocked with bisulfite.

More specifically, the biaxially oriented polyester adhesive film for optics having a surface hardness improving function according to the present invention comprises a biaxially oriented polyester film having a thickness of 50 to 300 μm in a base film and at least one side of the base film. A primer layer is formed as an adhesive layer, wherein the primer layer is a heat-reactive water-soluble urethane resin composed of an isocyanate group whose both ends are blocked with bisulfite, and a hydroxyl group, an acetate group, an alkoxy group, a carbodiimide group or an epoxy, jade in the polymer chain. Thermoreactive resin comprising a nucleophilic reactor such as cetane and aziridine, a tin catalyst, silica particles or alumina-silica composite oxide particles having an average particle diameter of 50 to 300 nm, anionic surfactants and alkali pH adjusters And it is applied with a coating liquid containing water, the coating liquid is the thermal reaction type receiving Urethane resin is a water-reactive water-soluble urethane resin water dispersion 1.0 to 10.0% by weight containing 20% by weight of the heat-reactive water-soluble urethane resin, the heat-reactive resin can be a heat-reactive resin containing 40% by weight of the heat-reactive resin Dispersion 1.0-5.0% by weight, Tin-based catalyst is 0.1-1.0% by weight of a tin-based catalyst aqueous dispersion containing 10% by weight tin-based catalyst, the silica particles or alumina-silica composite oxide particles are silica particles or alumina-silica composite 0.1 to 1.0% by weight of an aqueous dispersion of silica particles or alumina-silica composite oxide particles containing 70% by weight of oxide particles, and 0.1 to 1.0 of anionic surfactants containing 10% by weight of anionic surfactant. Wt%, the pH adjuster is characterized in that it comprises 0.5 to 2.0% by weight of the pH adjuster and the balance of water.

Here, the heat-reactive water-soluble urethane resin consisting of an isocyanate group whose both ends are blocked with bisulfite is represented by the following Chemical Formula 1.

[Formula 1]

As described above, a heat-reactive water-soluble urethane resin made of an isocyanate group having both ends blocked with bisulfite was used as the adhesive layer of the present invention. As the blocking agent for the isocyanate group, there are phenols and lactams containing sulfonic acid groups and bisulfite salts. And oximes, alcohols, and active methylene compounds.

In the case of the heat-reactive resin used in the present invention, compared to the melamine or epoxy curing agent used in general, by adding a hydrogen bond functional group in the molecule to increase the adhesion to the plastic substrate, the hardness by the interaction between the curing agent In addition, it has a function to improve the function of moisture resistance by increasing the polar interaction between the molecules of the heat-reactive resin composition.

In the case of the heat-reactive resin used in the present invention, it is not limited as a curing agent, but it is preferable to use a thermosetting agent which does not occur at low temperature but hardens at a high temperature. As the thermosetting agent, amine type, imidazole type, dihydrazide type can be used, but from the viewpoint of storage stability, it is preferable to use a dihydrazide type curing agent. Specific examples of the amine type are azicure MY-24, azicure MY-H, azicure MY-HK, azicure PN-23J, azicure PN-31J, azicure PN-40J (manufactured by Ajinomoto Co., Ltd.), Fujicure FXR- 1020, Fujicure FXR-1030 (manufactured by Fuji Kasei Co., Ltd.), and the like, and specific examples of the imidazole type include 2-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, and 2-phenyl. 4-methylimidazole (manufactured by Shikoku Chemical Co., Ltd.), and the like, and specific examples of the dihydrazide type include Ajicure VDH, Ajicure UDH (manufactured by Ajinomoto Co., Ltd.) ADH, SDH, DDH, and IDH (manufactured by Otsuka Chemical Co., Ltd.). , NDH (manufactured by Nippon Hydrazine Industrial Co., Ltd.), and the like, and may be used alone or in combination of two or more.

In the case of such a thermally reactive resin, it is a limiting factor in the use of a polyester film, for example, when exposed to a specific temperature such as an LCD protective film. When using biaxially oriented polyester film as an optical base film such as LCD, there is a possibility of surface deformation due to heat continuously from FCCL (cathode ray tube) after BLU assembly, and heat resistance is particularly important, and in this condition, Strength should also be maintained during conditions of high temperature or high temperature and high humidity. This is a thermosetting resin having a function of moisture resistance and a hardenability improvement, and is a thermal reaction type including a hydroxyl group, an acetate group, an alkoxy group, a carbodiimide group or a nucleophilic reactor such as epoxy, oxetane and aziridine in the polymer chain. It is going to form a primer layer using resin. In the case of the heat-reactive resin in the present invention, compared to the melamine or epoxy curing agent used in general, by adding a hydrogen bond functional group in the molecule to serve to increase the adhesion to the plastic substrate.

The thermally reactive resin has a chemical formula -N = C = N- as follows. This can be obtained by removing carbon dioxide from two isocyanate groups. 2 is a conceptual diagram of bonding of blocked isocyanate and thermally reactive resin.

By using polyisocyanate or diisocyanate as starting material, a compound comprising terminal isocyanate groups can be obtained in this way.

In addition, in the present invention, a tin-based catalyst may be used for the polymerization of the heat-reactive water-soluble urethane resin. Although the mechanism by the said catalyst is not accurate, it is thought that moisture resistance property improves by promoting reaction with the terminal group of a thermally reactive water-soluble urethane resin, and having excellent adhesive force with a polyester base material.

As the surfactant forming the primer layer of the biaxially oriented polyester film according to the present invention, a water-soluble coating solution can be used, and a known amount of anionic or nonionic surfactant is used in order to increase the wettability of the base film and to uniformly apply the coating solution. 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, and 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, when thicker than 3㎛ because the adhesive properties are excellent, but the transparency and coating properties are not preferred because it is not preferred.

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, antifoaming agents, and the like 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 do not help the running and scratch resistance in the film, but also does not give the effect of the fine particles, and when the average particle diameter of the fine particles exceeds 500nm causes a problem that 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 addition, the primer layer according to the present invention preferably comprises a pH adjusting agent of the alkaline component, the pH adjusting agent is characterized in that sodium hydrogen carbonate.

In the optical biaxially oriented polyester easy-adhesive film having a surface hardness improving function according to the present invention, 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 1.0%. The adhesion between the base film and the primer layer is characterized in that 100% after a 96 hours humidity resistance test at 65 ℃, 95% humidity. This is because it is impossible to apply the product if the adhesive strength is worse than the conventional product.

In addition, in the optical biaxially oriented polyester easy-adhesive film having a surface hardness improving function according to the present invention, the pencil hardness between the base film and the primer layer is characterized in that more than 1H, the pencil hardness is less than 1H in the post-processing process This is because the problem of poor handleability may occur.

In the optical biaxially oriented polyester adhesive film having a surface hardness improving function according to the present invention, the heat shrinkage between the base film and the primer layer is 0.8 or less in the TD and MD directions.

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

Example 1

First, the polyethylene terephthalate resin pellets were dried under reduced pressure (1.3 hPa) for 6 hours at 135 ° C., then fed to an extruder, and then melt-extruded into a sheet at about 280 ° C., and then on a metal roll maintained at a surface temperature of 20 ° C. Rapid cooling and solidification yielded a casting film having a thickness of 1925 µm. Next, the casting 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. 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 easily adhesive film having a thickness of 188 μm was obtained.

In Example 1, in the film formation of the biaxially oriented polyester film, after coating, the coating liquid was prepared and applied to an optical biaxially oriented polyester easy-adhesive film having a film thickness of 188 μm by applying the following method to improve surface hardness. The biaxially oriented polyester adhesive film for optics was obtained.

The coating liquid of the easily-adhesive layer forming the primer layer was thermally reacted with 10.0% by weight of a water-soluble urethane resin aqueous dispersion containing 60.0% by weight of water and 20.0% by weight of a urethane resin blocked with an isocyanate group and 60.0% by weight of water. 5.0 wt% of thermally reactive resin aqueous dispersion containing 40.0 wt% of resin type, 90 wt% of water and 10 wt% of tin-based catalyst for promoting the reaction of heat-reactive water-soluble urethane resin 1.0 wt% and 70.0 wt% of water are mixed, and 1.0 wt% of an aqueous dispersion of anionic surfactant containing 10 wt% of 90 wt% of water and anionic surfactant, and 70 wt% of water and colloidal silica particles 1.0% by weight of aqueous dispersion of colloidal silica particles contained in% by weight, and 2.0% by weight of sodium hydrogen carbonate in a separate container with 10.0% water in a separate container to adjust the pH of the coating liquid. Was dispersed by the addition of% was in the coating liquid.

[Example 2]

In the film formation of the biaxially oriented polyester film, the coating solution was prepared and then applied 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.

Comparative Example 1

In Comparative Example 1, in the film formation of the biaxially oriented polyester film, after the film formation, an optical biaxially oriented polyester easy-adhesive film having a thickness of 188 μm was prepared by applying a coating solution in the following manner and then applied to the optical biaxially oriented film. A polyester easy adhesive film was obtained.

The coating solution of the easily-adhesive layer forming the primer layer is a reaction of 15.0 wt% of a heat-reactive water-soluble urethane resin aqueous dispersion containing 80.0 wt% of water and 20.0 wt% of a urethane resin blocked with an isocyanate group, and reaction of a heat-reactive water-soluble urethane resin. To promote the reaction, the tin-based catalyst is mixed with 90% by weight of water, 1.0% by weight of an aqueous dispersion containing 10% by weight of tin-based catalyst, and 70.0% by weight of water, and 90% by weight of water as an anionic surfactant. 1.0 wt% of an aqueous dispersion containing 10 wt% of anionic surfactant, 1.0 wt% of an aqueous dispersion containing 70 wt% of colloidal silica particles and 30 wt% of water as colloidal silica particles, and a pH of the coating liquid In order to make the coating liquid, 2.0 weight% of sodium hydrogencarbonate was added to 10.0 weight% of water in the other container, and disperse | distributed to the pH adjuster of an alkali component.

Comparative Example 2

In the film formation of the biaxially oriented polyester film, the coating liquid was prepared and then applied in the same manner as in Comparative Example 1 except that the thickness of the cast film was 2200 μm and the film thickness was 250 μm.

Comparative Example 3

In Example 1, the coating liquid of the easily adhesive layer forming the primer layer is 60.0% by weight of water and 40.0% by weight of an aqueous dispersion containing 40.0% by weight of water, to promote the reaction of the heat-reactive water-soluble urethane resin, The tin-based catalyst is a mixture of 90% by weight of water, 1.0% by weight of an aqueous dispersion containing 10% by weight of tin-based catalyst, and 70.0% by weight of water.As an anionic surfactant, 90% by weight of water and anionic surfactant 1.0 wt% of aqueous dispersion containing 10 wt%, 1.0 wt% of aqueous dispersion containing 70 wt% of colloidal silica particles and 30 wt% of water as colloidal silica particles, and alkali 2.0 weight% of sodium hydrogencarbonate was added as a pH adjuster, and 10.0 weight% of water was disperse | distributed to another container, and it was set as the coating liquid.

[Comparative Example 4]

In the film formation of the biaxially oriented polyester film, an optical biaxially oriented polyester was prepared after the coating liquid was prepared in the same manner as in Comparative Example 3 except that the thickness of the cast film was 2200 μm and the film thickness was 250 μm. An easy adhesive film was obtained.

Experimental Example 1

The coating appearance of the films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 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 2 and Comparative Examples 1 to 4 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 X 2 mm squares in a 10 X 10 matrix. The cut lines are made deep enough to reach the substrate film through the adhesive layer. The cellophane tape (No. 405, width of NICHIBAN: 24 mm) is attached 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 symbol "o" in Table 1 represents 90% or more, and "X" represents less than 90%.

The adhesion test for evaluation of moisture resistance after 96 hours at 65 ° C. and 95% humidity is also performed in the same manner as above.

[Experimental Example 3]

Heat shrinkage of the films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 was measured. Heat shrinkage is determined from a square film sample with an edge length of 10 cm. Specimens are removed by moving one edge parallel to the machine direction and one edge moving perpendicular to the machine direction. Specimens are measured accurately (edge length L0 is determined for each machine direction TD and MD, L0 TD and L0 MD) and heat regulated for 30 minutes at the stated shrinkage temperature (here 150 ° C) in the drying cabinet with air circulation. The sample is removed and accurately measured at room temperature (edge length LTD and LMD). Contraction is calculated according to the following equation:

Shrinkage [%] MD = 100 · (L0 MD- LMD) / L0 MD

Shrinkage [%] TD = 100 · (L0 TD- LTD) / L0 TD

[Experimental Example 4]

Pencil hardness of the films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were measured. The surface pencil hardness of the film obtained above was measured using the pencil scraping tester (manual type) by Imoto Seisakusho Co., Ltd. based on the prescription | regulation of JISK5600-5-4 (1999 edition). In addition, the measured surface pencil hardness is shown in Table 1.

[Experimental Example 5]

The optical properties of the coating solution used in the films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 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 5 are shown in Table 1 below.

TABLE 1

division Coating appearance
(Up / mid / down) Adhesion
(%) Heat shrink
MD (%) / TD (%) Pencil hardness
(B-H) Optical properties
(TT / Hz) Example 1 Prize 100 0.7 / 0.5 1H 90.0 / 0.7 Example 2 Prize 100 0.6 / 0.5 1H ~ 2H 91.0 / 0.9 Comparative Example 1 Prize 100 1.1 / 0.8 B 90.0 / 1.1 Comparative Example 2 Prize 100 1.0 / 0.7 B-H 89.4 / 1.3 Comparative Example 3 Medium / Lower 80 1.1 / 0.8 B 88.4 / 1.4 Comparative Example 4 medium 70 1.0 / 0.7 B 87.9 / 1.3

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 excellent properties such as heat shrink, pencil hardness and optical properties. In the case of Comparative Examples 1 and 2, the coating appearance and adhesive strength are excellent, but the pencil hardness may be low, resulting in poor handling in the post-processing process. In addition, in the case of Comparative Examples 3 and 4, the coating appearance and adhesive force are poor in physical properties compared to the conventional products, and the product is not applicable.

1 is a cross-sectional view of an optical biaxially oriented polyester adhesive film having a surface hardness improving function according to the present invention.

2 is a conceptual diagram of bonding of blocked isocyanate and thermally reactive resin.

Claims (8)

In the biaxially oriented polyester adhesive film for optics having a surface hardness improvement function, A biaxially oriented polyester film having a thickness of 50 to 300 µm is formed of a base layer and a primer layer as a polymer adhesive layer on at least one side of the base film. The primer layer is a heat-reactive water-soluble urethane resin composed of an isocyanate group blocked at both ends with bisulfite and a nucleophilic group such as hydroxy group, acetate group, alkoxy group, carbodiimide group or epoxy, oxetane and aziridine in the polymer chain. A coating liquid containing a thermally reactive resin including a reactor, a tin catalyst, silica particles or alumina-silica composite oxide particles having an average particle diameter of 50 to 300 nm, an anionic surfactant, an alkali pH adjuster, and water. Applied, The coating liquid is a heat-reactive water-soluble urethane resin 1.0 to 10.0% by weight of the heat-reactive water-soluble urethane resin containing 20% by weight of the heat-reactive water-soluble urethane resin, The thermally reactive resin is a thermally reactive resin aqueous dispersion 1.0 to 5.0% by weight, including 40% by weight of the thermally reactive resin, The tin-based catalyst is 0.1 to 1.0% by weight of a tin-based catalyst aqueous dispersion containing 10% by weight of a tin-based catalyst, The silica particles or alumina-silica composite oxide particles may be silica particles or alumina-silica composite oxide particles containing 70% by weight of silica particles or alumina-silica composite oxide particles in an aqueous dispersion of 0.1 to 1.0% by weight, The anionic surfactant is 0.1 to 1.0% by weight of an anionic surfactant dispersion containing 10% by weight of anionic surfactant, The pH adjusting agent is 0.5 to 2.0% by weight of pH adjusting agent and the remaining amount of water, biaxially oriented polyester adhesive film for optics with a surface hardness enhancement function. The method of claim 1, The pH adjusting agent is sodium bicarbonate, biaxially oriented polyester adhesive film for optics with a surface hardness enhancement function. 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 1.0%. The method of claim 1, The adhesion between the base film and the primer layer is 100% after a 96 hours humidity resistance test under 65 ℃, 95% humidity, biaxially oriented polyester adhesive film for optics with a surface hardness enhancement function. The method of claim 1, The pencil hardness between the base film and the primer layer is 1H or more, biaxially oriented polyester adhesive film for optics with a surface hardness enhancement function. The method of claim 1, Thermal shrinkage between the base film and the primer layer is 0.8 or less in the TD and MD direction, biaxially oriented polyester adhesive film for optics with a surface hardness enhancement function. The method of claim 1, The primer layer is applied after uniaxial stretching of the biaxially oriented polyester film, biaxially oriented polyester bi-adhesive film for optics with a surface hardness enhancement function. The method of claim 1, The thickness of the primer layer is characterized in that 0.05 ~ 3.00㎛, biaxially oriented polyester adhesive film for optics with a surface hardness enhancement function.

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