KR20110051801A - Biaxially-oriented polyester adhesive film with copolymeric polyester resin for improving surface leveling property - Google Patents

Abstract

PURPOSE: A biaxially-oriented polyester adhesive film is provided to improve a levering property of a primer layer used for a biaxially oriented polyester film, and to ensure high optical characteristic and winding property. CONSTITUTION: A biaxially-oriented polyester adhesive film with improved surface leveling property comprises: a biaxially oriented polyester substrate film with thickness of 50~300 micron; and a primer layer including a copolymerized polyester resin having carboxyl groups at the terminal, as a polymer adhesive layer. The thickness of the primer layer is 0.10~0.50 micron.

Description

Biaxially oriented polyester adhesive film having improved surface leveling property including copolyester resin {BIAXIALLY-ORIENTED POLYESTER ADHESIVE FILM WITH COPOLYMERIC POLYESTER RESIN FOR IMPROVING SURFACE LEVELING PROPERTY}

The present invention relates to a biaxially oriented polyester easy-adhesive film having improved surface leveling property, including a copolyester resin, and more particularly, a primer layer used for a biaxially stretched polyester film may have sufficient adhesiveness with a substrate. The present invention relates to a biaxially oriented polyester easy-adhesive film having improved surface leveling property, including a copolyester resin having excellent optical properties, excellent winding properties, and excellent appearance properties.

Recently, as interest in liquid crystal displays, organic light emitting 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.

On the other hand, in order to be used as a polyester film of a display device, high light transmittance, winding property, and excellent appearance characteristics of the surface are required, and in particular, properties such as improvement of adhesion with a functional UV resin for imparting a function in a post-processing process are required. .

In the case of many conventional polyester films, in order to achieve high light transmittance, inorganic particles used in the melt extrusion process during PET film formation are removed or draw ratios are adjusted. In this case, yield reduction due to film production Problems such as thickness non-uniformity of the PET substrate may occur, and thickness non-uniformity of the base film according to the stretching magnification may have a problem of causing thickness non-uniformity of the primer layer. In addition, such a lack of leveling properties of the primer layer causes poor appearance and poor optical properties, and at the same time, problems such as a lack of local adhesion to the PET substrate and a lack of adhesion to the UV resin in the post-processing process.

The present invention has been made to solve the above problems, the object of the present invention is to improve the leveling properties of the primer layer used in the biaxially stretched polyester film, thereby not only sufficient adhesiveness with the substrate, but also high optical properties And it is to provide a biaxially oriented polyester easy-adhesive film having improved surface leveling properties, including the co-polyester resin having a winding property, and excellent appearance properties of the base film after coating due to the improved leveling property.

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

The above object is, in the biaxially oriented polyester easy-adhesive film with improved surface leveling property of improving the surface leveling property of the primer layer, the biaxially oriented polyester base film having a thickness of 50 ~ 300㎛ and at least one side of the base film As the polymer adhesive layer, a primer layer including a copolyester polyester resin having a carboxyl group is formed at a terminal thereof, and the primer layer has a thickness of 0.10 to 0.50 μm, thereby improving the surface leveling property of the copolyester polyester resin. It is achieved by a biaxially oriented polyester adhesive film.

Here, the easy-adhesive layer is a silica particle containing 1.0 to 10.0% by weight of an aqueous dispersion of copolymerized polyester resin containing 40% by weight of a copolymerized polyester resin having a carboxyl group, silica particles or 70% by weight of alumina-silica composite oxide particles. Or 0.5-3.0 wt% of an aqueous dispersion of alumina-silica composite oxide particles, 0.5-2.0 wt% of an anionic surfactant containing 10 wt% of anionic surfactant, and 70.0 wt% of a melamine curing agent. Characterized in that the coating liquid consisting of -3.0% by weight and the residual amount of water.

Preferably, the surface of the base film on which the primer layer is formed is characterized in that the total light transmittance is 92% 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 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 base film.

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 effects of high optical properties and winding properties and appearance properties.

In addition, the present invention can increase the adhesive strength with the UV resin during the post-processing, such as prism lens processing, hard coat processing, AR processing, etc. can increase the product yield.

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 a biaxially oriented polyester easy-adhesive film having improved surface leveling property including a copolyester resin according to the present invention.

Optical biaxially oriented polyester easy-adhesive film having a leveling property improving function of the primer layer according to the present invention relates to a biaxially oriented polyester film having excellent adhesion in a post-processing step, during the manufacturing process of the biaxially oriented polyester film The primer layer is characterized by comprising a copolyester resin having a carboxyl group at the terminal. Co-polyester resin having a carboxyl group at this end is shown in FIG.

The copolyester resin used in the biaxially oriented polyester easily-adhesive film with improved surface leveling property including the copolyester resin according to the present invention preferably comprises a dicarboxylic acid component and a branched glycol component as components. . 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. .

The branched glycol component is preferably contained in a proportion of 10 mol% or more in the total glycol component, and particularly preferably 20 mol% or more. In addition, the branched glycol component is preferably contained at a rate of 80 mol% or less in the total glycol component. If it is less than 10 mol%, there exists a tendency for 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.

Moreover, as dicarboxylic acid component contained as a component in co-polyester type resin, terephthalic acid and isophthalic acid are the most preferable. 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.

In the case of the melamine resin applied to the primer layer according to the present invention, by additionally containing a hydrogen bonding functional group in the molecule, it serves to increase the adhesion to the plastic substrate.

In addition, the surfactant applied to the primer layer according to the present invention is a water-soluble coating solution can be used, and applied to the base film using a known amount of anionic or nonionic surfactant required to increase the wettability of the base film and to uniformly apply the coating solution. It is desirable to.

Moreover, the primer layer which concerns on this invention is formed by apply | coating with a resin binder etc. on the film after uniaxial stretching of a biaxially-oriented polyester film. At this time, the thickness of the primer layer to which the resin is applied is preferably 0.05 to 1.00 μm, more preferably 0.10 to 0.50 μm. If the thickness of the primer layer is less than 0.10㎛ coating loss is lost due to the coating or the optical properties are worse than 0.50㎛ because the adhesive properties are excellent, but the appearance of the stain, the film peeling phenomenon occurs during film formation It is most preferable to set it as said range.

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 does not help runability and scratch resistance in the film, but also does not give an effect of the fine particles, and when the average particle diameter of the fine particles exceeds 500nm, there is a problem that haze the 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.

The easy-adhesive layer according to the present invention comprises 1.0 to 10.0% by weight of an aqueous dispersion of copolymerized polyester resin containing 40% by weight of copolymerized polyester resin, silica particles or alumina- containing silica particles or 70% by weight of alumina-silica composite oxide particles. Melamine curing agent aqueous dispersion containing 0.5-3.0 wt% of silica composite oxide particle aqueous solution, 0.5-2.0 wt% of anionic surfactant aqueous solution containing 10 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent 1.0-3.0 wt% It is characterized by being applied with a coating liquid consisting of% and the residual amount of water.

In addition, the surface of the base film on which the primer layer is formed according to the present invention is characterized in that the total light transmittance is 92% or more, and the haze value is 0.4 to 1.0%, and the adhesion between the base film and the primer layer is 65 ° C. It is characterized in that 100% after a 96 hours humidity resistance test under 95% humidity. This is because it is impossible to apply the product if the adhesive strength is worse than the conventional product.

In addition, the heat shrink between the base film and the primer layer according to the present invention is preferably 0.8 or less in the TD and MD direction.

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) at 135 ° C. for 6 hours, and then fed to an extruder, and then melt-extruded into a sheet at about 280 ° C., and then maintained at a surface temperature of 20 ° C. Rapid cooling on the solid phase gave a casting film having a thickness of 1925 μm. Next, the cast film is heated to a heated roll group and an infrared heater 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 the film formation, a coating liquid was prepared and applied to an optical biaxially oriented polyester easy-adhesive film having a thickness of 188 μm in the following manner, and then applied to level the primer layer. An optical biaxially oriented polyester easy-adhesive film having a performance improving function was obtained.

The coating liquid of the easily-adhesive layer forming the primer layer is 89.0% by weight of water, and 6.0% by weight of the copolymerized polyester resin aqueous dispersion containing 40.0% by weight of the copolymerized polyester resin having a carboxyl group, silica particles or alumina-silica composite oxide. 2.0 wt% of silica particles or alumina-silica composite oxide particles containing 70.0 wt% of particles, 1.0 wt% of anionic surfactant dispersion containing 10.0 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent. Melamine curing agent aqueous dispersion 2.0% by weight was added to disperse to give a 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 of Example 1, the coating liquid was prepared and applied to the biaxially oriented polyester easy-adhesive film for optics having a thickness of 250 μm after film formation by the following method. An optical biaxially oriented polyester easy adhesive film was obtained.

The coating liquid of the easily-adhesive layer forming the primer layer is 93.0% by weight of water and 2.0% by weight of a copolymer polyester resin aqueous dispersion containing 40.0% by weight of a copolymerized polyester resin having a carboxyl group at the end, silica particles or alumina-silica composite oxide. 2.0 wt% of silica particles or alumina-silica composite oxide particles containing 70.0 wt% of particles, 1.0 wt% of anionic surfactant dispersion containing 10.0 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent. Melamine curing agent aqueous dispersion 2.0% by weight was added to disperse to give a coating liquid.

Comparative Example 2

In Comparative Example 2, in the film formation of the biaxially oriented polyester film of Example 1, after the film formation, a coating liquid was prepared and applied to an optical biaxially oriented polyester easy-adhesive film having a thickness of 250 μm by the following method. A biaxially oriented polyester easy adhesive film was obtained.

The coating liquid of the easily-adhesive layer forming the primer layer comprises 91.0% by weight of water and 4.0% by weight of a copolymerized polyester resin aqueous dispersion containing 40.0% by weight of a copolymerized polyester resin having a carboxyl group, silica particles, or alumina-silica composite oxide. 2.0 wt% of silica particles or alumina-silica composite oxide particles containing 70.0 wt% of particles, 1.0 wt% of anionic surfactant dispersion containing 10.0 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent. Melamine curing agent aqueous dispersion 2.0% by weight was added to disperse to give a coating liquid.

Comparative Example 3

In Comparative Example 3, in the film formation of the biaxially oriented polyester film of Example 1, the coating liquid was prepared and applied to the biaxially oriented polyester easy-adhesive film for optics having a thickness of 250 μm after film formation by the following method. A biaxially oriented polyester easy adhesive film was obtained.

The coating liquid of the easily-adhesive layer forming the primer layer is 8.0% by weight of an aqueous dispersion of copolymerized polyester resin containing 87.0% by weight of water and 40.0% by weight of a copolymerized polyester resin having a carboxyl group at the end, silica particles or alumina-silica composite oxide. 2.0 wt% of silica particles or alumina-silica composite oxide particles containing 70.0 wt% of particles, 1.0 wt% of anionic surfactant dispersion containing 10.0 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent. Melamine curing agent aqueous dispersion 2.0% by weight was added to disperse to give a coating liquid.

[Comparative Example 4]

In Comparative Example 4, in the film formation of the biaxially oriented polyester film of Example 1, the coating liquid was prepared and applied to the biaxially oriented polyester easy-adhesive film for optics having a thickness of 250 μm after film formation by the following method. A biaxially oriented polyester easy adhesive film was obtained.

The coating liquid of the easily-adhesive layer forming the primer layer is 10.0% by weight of an aqueous dispersion of copolymerized polyester resin containing 85.0% by weight of water and 40.0% by weight of a copolymerized polyester resin having a carboxyl group at the end, silica particles or alumina-silica composite oxide. 2.0 wt% of silica particles or alumina-silica composite oxide particles containing 70.0 wt% of particles, 1.0 wt% of anionic surfactant dispersion containing 10.0 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent. Melamine curing agent aqueous dispersion 2.0% by weight was added to disperse to give a coating liquid.

Experimental Example 1

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 × 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.

In addition, the adhesion test for evaluation of moisture resistance after 96 hours at 65 ° C. and 95% humidity was 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 in such a way that one edge moves parallel to the machine direction and one edge moves perpendicular to the machine direction. Specimens are accurately measured (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 specimen 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]

Coating thicknesses of the films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were measured. Coating thickness of the primer layer obtained in the above was used a UV-vis spectrophotometer. (UV-3600 manufactured by SHIMADZU Co., Ltd.) The measurement wavelength range was determined at 300-3000 nm.

The thickness of the measured wavelength is calculated by the following equation.

ndcosθ = (λ _Rmin / 4)

n is the refractive index of the copolyester-based resin, the incident angle of the UV-vis spectrophotometer is cos 5 degrees, and the wavelength d of the measurement result is put in λ _Rmin to calculate the thickness d. The measured optical thickness 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 PET thickness
(Μm) Coating appearance
(Up / mid / down) Adhesion
(%) Heat shrink
MD (%) / TD (%) Coating thickness
(nm) Optical properties
(TT / Hz) Example 1 188 Prize 100 0.7 / 0.5 140 92.2 / 0.7 Example 2 250 Prize 100 0.6 / 0.5 180 92.3 / 0.9 Comparative Example 1 250 medium 80 0.7 / 0.5 70 88.0 / 1.1 Comparative Example 2 250 medium 90 0.6 / 0.4 85 89.4 / 1.3 Comparative Example 3 250 Ha 100 0.7 / 0.5 540 92.4 / 1.4 Comparative Example 4 250 Ha 100 0.6 / 0.5 665 93.5 / 1.3

As can be seen in Table 1, Examples 1 and 2 can be seen that the coating thickness and optical properties as well as the coating appearance and easy adhesion with the substrate as compared to the comparative examples.

In the case of Comparative Examples 3 and 4, the adhesion was excellent, but coating appearance defects occurred in the form of stains when the surface of the PET substrate was observed after coating, and thus the application of the product was impossible. In addition, as in Comparative Examples 1 and 2, if the adhesive force does not come out 100% is not applicable to the product.

Accordingly, the biaxially oriented polyester easy-adhesive film having improved surface leveling property, including the copolyester resin according to the present invention, is not only sufficient adhesiveness with the substrate but also high optical properties and a primer layer used in the biaxially stretched polyester film. It has an excellent effect of winding and appearance characteristics, and can increase the product yield by increasing adhesion to UV resin during post-processing such as prism lens processing, hard coat processing, and AR processing, and also has high combat rate and high haze value. Because of its small properties, it can be used throughout various optical members, especially as optical films, such as base films for prism sheets or base films for backlights, base films for hard coat processing or AR films, and protective films in CRTs. It is effective as such and the like.

1 is a cross-sectional view of a biaxially oriented polyester easy-adhesive film having improved surface leveling property including a copolyester resin according to the present invention.

2 is a conceptual diagram of bonding of a copolyester resin comprising a carboxyl group at a terminal included in the primer layer of the present invention.

Claims (6)

In the biaxially oriented polyester easy-adhesive film with improved surface leveling property of improving the surface leveling property of the primer layer, Biaxially oriented polyester base film having a thickness of 50 ~ 300㎛, As a polymer easily adhesive layer on at least one side of the base film, to form a primer layer comprising a copolyester resin having a carboxyl group at the terminal, characterized in that the thickness of the primer layer is 0.10 ~ 0.50㎛, copolyester Biaxially oriented polyester easily-adhesive film with improved surface leveling property, including resin. The method of claim 1, The easy-adhesive layer may include silica particles or alumina containing 1.0 to 10.0% by weight of an aqueous dispersion of copolymerized polyester resin containing 40% by weight of a copolymerized polyester resin having a carboxyl group, and 70% by weight of silica particles or alumina-silica composite oxide particles. Melamine curing agent aqueous dispersion containing 0.5-3.0 wt% of silica composite oxide particle aqueous solution, 0.5-2.0 wt% of anionic surfactant water dispersion containing 10 wt% of anionic surfactant, and 70.0 wt% of melamine curing agent. A biaxially oriented polyester easy-adhesive film having improved surface leveling property, comprising a copolyester resin, which is applied with a coating liquid consisting of a weight% and a residual amount of water. The method of claim 1, The surface of the base film on which the primer layer is formed has a total light transmittance of 92% or more, and a haze value of 0.4 to 1.0%. film. The method of claim 1, Adhesion between the base film and the primer layer is 100% after a 96 hours humidity resistance test at 65 ℃, 95% humidity, biaxially oriented polyester easy adhesion comprising a copolyester resin improved surface leveling film. 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 easy-adhesive film with improved surface leveling properties, including a co-polyester resin. 6. The method according to any one of claims 1 to 5, The primer layer is biaxially oriented polyester easy-adhesive film with improved surface leveling properties, characterized in that the coating is applied after uniaxial stretching of the biaxially oriented polyester base film.

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