KR20140042390A - Polyester laminated film - Google Patents

Abstract

The present invention relates to a polyester laminated film, and specifically, to a polyester laminated film for packing food. The polyester laminated film for packing food includes a polyester substrate film, and a polyurethane based primer coating layer, an adhesive layer, and a clouding resistant coating layer successively laminated on one surface of the substrate film. The adhesive power of the adhesive layer satisfies equation 1: 1500 gf/inch >= adhesive power of the adhesive layer >= 500 gf/inch, and the contact angle of the clouding resistant coating layer satisfies equation 2: contact angle of the clouding resistant coating layer <=10°.

Description

[0001] POLYESTER LAMINATED FILM [0002]

The present invention relates to a polyester laminated film, and relates to a polyester laminated film for food packaging.

It is no exaggeration to say that Hyundai is the era of functional packaging, and products with consumer convenience are gaining popularity on the market. Simple cooked foods that are simply heated using ovens or microwave ovens such as pizza, frozen foods and bacon are growing rapidly.

One of the methods of packaging these products is a packaging method using a peelable seal film. In other words, in the past, the focus was on simply strengthening the sealing property of the package so that the package was not opened during production or distribution. The development direction is being pursued. However, it is assumed that the contents are not leaked (opened or damaged) during the existing production and distribution process. In addition, the Peelable seal film for packaging such a simple cooked food is in the direction of providing anti-fog, which is a function that can enhance the freshness and aesthetic effect of the product in order to prevent fogging generated during refrigeration or heating and cooking. The change in the market is also seen in the diversification of packaging containers and materials. In the past, small-business-oriented products have been transformed into more than SMEs, requiring various forms of packaging in the production and distribution process.

As an example of such a Peelable seal, Korean Patent Publication No. 10-2004-0037095 (2004.05.04) relates to a multilayer polymer film for packaging food for the oven, having a polymer heat-sealable peelable layer on one side and the opposite side A polymeric substrate layer having a polymer shrinkable layer on a face, the shrinkable layer having a shrinkage of about 10 to 80% at a first dimension over a temperature range of 55-100 ° C., at 100 ° C. One or two intermediate layers disposed in the orthogonal second dimension in the range of 1: 1 to 10: 1 and disposed between the substrate layer and the shrinkable layer and / or between the substrate layer and the heat-sealable peelable layer ( (S) and a layer (s) of one or more electrically conductive materials are described.

Looking at the direction and shape of the Peelable Seal, there is a method of applying a Peelable Seal function to the film to heat seal the container, a method of applying the Peelable Seal function to the container, a method of providing the Peelable Seal function between the films. The peelable seal market currently maintained is partially limited due to the price of expensive films and raw materials, but basically considering the convenience of consumption, it is a concept that is the basis in the future packaging market. Considered or existing products are also expected to change with this trend. Especially in the US market, Peelable seal products have already formed a large market as described above, and the demand for anti-fogging performance is gradually increasing.

The present invention is a Peelable seal polyester film provided with anti-fogging properties, and is largely divided for the whole packaging or for the lid. The required characteristics are first, heat adhesion (140 to 180 ° C.), and second, easy peeling by hand. Third, cooking should be possible in a microwave oven as well as a general heating oven. Fourth, a water film should be formed on the film surface to prevent fogging.

Factors related to the adhesion of the film as described above depends on the thickness of the adhesive layer to be applied during film production, the type of adhesive polymer, and the amount of filler incorporated therein. The adhesive polymer should be invented in such a way that the manufacturing cost of the raw material is so high that the coating amount is lowered and the adhesive force is increased. In order to have anti-fogging performance, the anti-fogging layer should have characteristics of superhydrophilicity (less than 10 °) or superhydrophobicity (more than 150 °). When the anti-fog layer is formed, problems occur due to deterioration of adhesion performance, blocking, and transfer to the back, and various research and developments have been made to improve this.

The present inventors have tried to solve the above problems such as adhesiveness, anti-fogging property, blocking property, transfer, etc. As a result, the adhesive layer is excellent in the cross-section of the base film, the blocking property, and easy to control the transfer performance to the back The present invention was completed by preparing an antifogging polyester film double coated with an edible emulsifier having excellent anti-fogging performance and less adhesive force on the adhesive layer.

Korean Patent Publication No. 10-2004-0037095 (2004.05.04)

An object of the present invention is to provide an anti-fogging polyester laminated film excellent in adhesion performance and anti-fogging properties by securing an excellent anti-fogging performance and back transfer stability using an edible polymer emulsifier and improving the adhesion performance and blocking properties of the adhesive layer.

The present invention for achieving the above object is a polyurethane-based primer coating layer, an adhesive layer and an anti-fogging coating layer is sequentially formed on one surface of the polyester base film, the base film,

The adhesive force of the said adhesive layer satisfies following formula 1, and the contact angle of the said antifogging coating layer relates to the polyester laminated film which satisfy | fills following formula 2.

[Formula 1]

1500gf / inch ≥ adhesion of adhesive layer ≥ 500gf / inch

[Formula 2]

Contact angle of anti-fog coating layer ≤10 °

In the present invention, the adhesive layer comprises a polyester-based binder resin, a filler and a filler, a first polyester resin having a glass transition temperature of 50 ~ 80 ℃, a second polyester resin having a glass transition temperature of 0 ~ 30 ℃ It may be.

In the present invention, the polyester-based binder resin may include 5 to 30% by weight of the first polyester resin, and 70 to 95% by weight of the second polyester resin.

In the present invention, the filler is a silica particle having an average particle diameter of 1 ~ 5㎛, may be included in 0.1 to 0.8% by weight.

In the present invention, the antifogging coating layer may be dissolved in water, and may include an edible emulsifier that is solid at room temperature.

In the present invention, the emulsifier may be one or a mixture of two or more selected from glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester and lecithin.

In the present invention, the base film has a thickness of 12 ~ 50㎛, the polyurethane-based primer coating layer has a dry coating thickness of 0.03 ~ 0.1㎛, the adhesive layer has a dry coating thickness of 1 ~ 5㎛, the antifogging coating layer has a dry coating thickness It may be 0.07 ~ 0.2㎛.

The polyester film of the present invention is expected to have high transparency and permeability, excellent adhesion and anti-fogging property of the post-processing coating agent, and various applications and applications throughout the packaging industry.

1 is a cross-sectional view showing one embodiment of the present invention.
Figure 2 shows an excellent measure when visual evaluation of the present invention.

More specifically, with reference to the drawings will be described an embodiment of the present invention.

Figure 1 shows an embodiment of the present invention, as shown in Figure 1, the present invention is a polyester base film 10, the polyurethane-based primer coating layer 20, the adhesive layer 30 on one surface of the base film And anti-fog coating layer 40 is formed sequentially,

The adhesive force of the said adhesive layer satisfies following formula 1, and the contact angle of the said antifogging coating layer relates to the polyester laminated film which satisfy | fills following formula 2.

[Formula 1]

1500gf / inch ≥ adhesion of adhesive layer ≥ 500gf / inch

[Formula 2]

Contact angle of anti-fog coating layer ≤10 °

The adhesive strength of the adhesive layer is 500gf / inch or more, specifically 500 ~ 1500gf / inch, the contact angle of the anti-fogging coating layer is 10 ° or less, specifically 0 ~ 10 ° in the range, excellent adhesion and anti-fogging property of the post-processing coating agent food It is advantageous to apply it as a packing material for packaging. If the adhesive strength is lower than 500gf / inch, there is a problem of sealing property by the weight of the contents after packaging, and if it is higher than 1500gf / inch, it is difficult to peel off the film. If the contact angle is more than 10 ° water vapor on the surface of the film to form a sphere, it is difficult to form a water film within a few seconds, the lower the contact angle is advantageous anti-fogging property.

In one aspect of the present invention, it is preferable that the polyester base film 10 uses a polyester film, more specifically a polyethylene terephthalate film. The base film is preferably a thickness of 12 ~ 50㎛. If the thickness is less than 12㎛ may be lacking mechanical properties and heat resistance, if the thickness exceeds 50㎛ may be limited to use stably in the post-processing process.

In one embodiment of the present invention, the polyurethane-based primer coating layer 20 is formed to improve the adhesion between the base film and the adhesive layer, and to remove the adhesive binder remaining in the adherend during the final evaluation of the product, usually poly If the composition used to form the primer coating layer when producing the ester film may be used without limitation. However, in order to improve the adhesiveness with the adhesive layer for expressing the adhesiveness desired in the present invention and to have excellent transparency and transmittance, it is preferable to use a polyurethane-based binder resin having a small difference in refractive index from the polyester base film. . If the adhesive binder remains on the adherend when the film is removed as a product used for food packaging, it will have a negative effect on the appearance and the end user's preference when ingesting food. do.

The primer composition for forming the polyurethane-based primer coating layer 20 is preferably a solid content of 4 to 10% by weight of the polyurethane-based binder resin. In the above range, the appearance and blocking properties of the polyurethane-based primer coating layer may be advantageous and excellent in transparency and permeability.

The polyurethane primer coating layer 20 is preferably a dry coating thickness of 0.03 ~ 0.1㎛. If the polyurethane-based primer coating layer is less than 0.03㎛ can not see the effect, if it exceeds 0.1㎛, blocking property may occur, and the coating layer strength may be weakened.

In one aspect of the present invention, the adhesive layer 30 is to heat-fix the adherend to protect food in the adherend and to give a function that can easily remove the film when used by the end consumer, the glass transition temperature in the present invention Is characterized by using a mixture of two different polyester resins. By using a polyester having a different glass transition temperature, the mutually opposite effects of adhesion and blocking properties can be maintained at an optimal level, and in particular, an excess of a polyester resin having a low glass transition temperature can minimize the loss of adhesion.

More specifically, the adhesive layer includes a polyester-based binder resin in which a first polyester resin having a glass transition temperature of 50 to 80 ° C., a second polyester resin having a glass transition temperature of 0 to 30 ° C., and a filler are included. It may be.

An adhesive composition for forming the adhesive layer, the polyester-based binder resin 10 ~ mixture of the first polyester resin having a glass transition temperature of 50 ~ 80 ℃ and the second polyester resin having a glass transition temperature of 0 ~ 30 ℃ 40 weight percent, filler 0.1-0.8 weight percent and residual solvent.

The polyester binder resin is preferably used by mixing 5 to 30% by weight of the first polyester resin and 70 to 95% by weight of the second polyester resin. When the first polyester resin is less than 5% by weight and the second polyester resin is more than 95% by weight, the adhesion of the final product may increase, but blocking may occur, causing process problems. When the polyester resin is more than 30% by weight and the second polyester resin is less than 70% by weight, the blocking property is excellent, but the adhesion is low, which may cause a problem that the film is peeled off by the flow of the contents during heat setting in the final product.

10 to 40% by weight of a polyester-based binder resin in which the first polyester resin having a glass transition temperature of 50 to 80 ° C. and the second polyester resin having a glass transition temperature of 0 to 30 ° C. is prepared when the adhesive composition is prepared. When the solid content is less than 10% by weight, the coating property and the blocking property are good, but it is difficult to realize the adhesive force, and when it is more than 40% by weight, the adhesion is excellent but coating appearance and blocking property may occur. As the viscosity of the coating liquid rises, the coating appearance may become poor.

Colloidal silica particles may be used as the filler, but is not limited thereto. It is preferable that the average particle diameter of the said silica particle is 0.1-5 micrometers, It is preferable to use it at 0.1-0.8 weight%, It may be any one or a mixture of 2 or more selected. This is because it is difficult to solve the blocking property because most of the particles less than 0.1㎛ is buried in the adhesive binder and the particles larger than 5㎛ is too large than the thickness of the adhesive layer, which causes the problem that the particles fall off, it is advantageous to use the particles in the above range Do.

The solvent is not limited as long as it can dissolve the binder resin, and specifically, for example, methyl ethyl ketone, toluene, or the like can be used.

In one aspect of the invention, the adhesive layer 30 is preferably a dry coating thickness of 1 ~ 5㎛. If it is less than 1㎛ occurs a problem that the adhesive strength is lowered, if it exceeds 5㎛ causes the problem that the adhesive strength is increased can not be easily removed.

In one aspect of the present invention, the anti-fog coating layer 40 is more vivid by forming a water film on the surface of the film by a method for maximizing the identification and aesthetic appearance effect of the consumer due to the steaming occurs in the distribution and display of the final product In order to impart a function of seeing the transparent interior, in the present invention, it may be dissolved in water, and may include an edible emulsifier that is solid at room temperature.

More specifically, the antifogging coating liquid for forming the antifogging coating layer 40 may be dissolved in a solvent and may include 1 to 10% by weight of an edible emulsifier which is solid at room temperature and a residual amount of solvent. Coating the emulsifier in the above range can maximize the anti-fogging performance, but less than 1% of the hydrophilic group is insufficient, if the excess of 10% hydrophobic group is located in the upper layer is disadvantageous in expressing the anti-fogging property of the main performance.

The emulsifier may be any one or a mixture of two or more selected from glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester and lecithin, but is not limited thereto. Commercialized examples include REKENVITAMIN, REKEMAL series, and the like.

The solvent may be isopropyl alcohol, water and the like.

In one aspect of the invention, the anti-fogging coating layer 40 may be a dry coating thickness of 0.07 ~ 0.2㎛. As in the above description, when less than 0.07 μm or more than 0.2 μm, the antifogging property is lowered. In particular, when it exceeds 0.2 μm, the antifogging coating layer may be transferred to the film back surface.

Hereinafter, although the manufacturing method of the polyester laminated | multilayer film of this invention is demonstrated in detail, it is not limited to this.

In the single-coated polyester film according to the present invention, the polyester resin melt-extruded to prepare an amorphous polyester sheet (Sheet), uniaxially stretched in the same longitudinal direction as the sheet moving direction, and then uniaxially stretched polyester sheet After coating the polyurethane-based composition to dry the coating solution and at the same time prepared by preheating the sheet, stretching in the transverse direction and heat treatment. Thereafter, after applying the polyester-based adhesive binder with an offline double coating, it may be prepared by drying the hot air and applying an edible emulsifier type anti-fogging coating liquid to the upper part by drying again.

More specifically, the raw material resin of the polyester is sufficiently vacuumed, dried and then melted and extruded through an extruder, and the molten hot polyester resin is made into a sheet in a rotary cooling roll through a die. At this time, the unstretched polyester sheet is obtained by bringing the polymer into close contact with the cooling roll by the electrostatic application method. In this case, the silica raw material may be mixed with the polyester raw material resin or may be added in the polyester polymerization step to polymerize the master batch, and may be used by mixing with the base material to which the silica particles are not added. The unstretched polyester sheet thus obtained is stretched 2.5 to 4.0 times in the longitudinal direction while passing through a roll heated to 80 to 110 ° C to obtain a uniaxially stretched polyester film. After applying the polyurethane coating solution to the cross-section of the prepared uniaxially stretched polyester film, it is preheated and dried at 100 to 140 ° C. and stretched 2.5 to 4.0 times in the transverse direction, and then heat treated at 200 to 235 ° C. in the tenter heat treatment zone. . Subsequently, the film is heat-set in the cooling zone by relaxing 0.01 to 10% in the longitudinal or transverse direction at a temperature of 190 ° C. or lower to prepare a biaxially stretched polyester film having a single-side coating layer. In the post-processing, the roll film is coated with an adhesive layer coating solution by a double coating method, heat-dried at 100 to 150 ° C. in a 5-step tenter, and then coated with an anti-fogging coating solution in succession, and then heated to 100-150 ° C. in a 5-step tenter. The drying is carried out to prepare a polyester film.

  As a method of applying the adhesive layer and the antifogging layer coating liquid to the polyester film, one of these methods is used in the known coating methods such as gravure coating method, key coating method, wire bar coating method, spray coating method and air knife coating method. It may also be carried out in branches or in combination.

The polyester film coated with the adhesive layer and the anti-fogging layer according to the present invention has the advantage of excellent adhesive strength and anti-fogging function and excellent anti-blocking performance and transfer performance to the back.

Hereinafter, the present invention will be described in detail with reference to the following examples. The following examples illustrate the present invention, but the scope of the present invention is not limited to the following examples.

Required properties of the present invention and specific details for measuring the same are as follows.

(1) adhesive

The polyester films prepared in Examples and Comparative Examples were laminated on APET (amorphous polyester film) and CPET (crystalline polyester film), and then 0.4 MPa at 100 to 200 ° C. using Heat Gradient (Japan Toyosei Co., Ltd.). Press for 1 second under pressure and leave for 1 hour at room temperature. Peel Tester (Cheminstrument Co., AR-1000) Peeling the film bonded to a width of 25mm at a speed of 300mm / min 90 °. It is 500gf / inch based on CPET and 700gf / inch based on APET and has excellent adhesiveness.

Excellent (O): 500gf / inch based on CPET, 700gf / inch based on APET

Poor (X): 500gf / inch based on CPET, 700gf / inch based on APET

(2) contact angle performance

Using a dynamic contact angle measuring instrument (DSA100, KRUSS Co., Ltd.), 3 μl of water droplets were dropped on the polyester films prepared in Examples and Comparative Examples to measure the contact angle of water droplets measured within 10 seconds. If the contact angle is 10 ° or less, the antifogging property is excellent.

(3) visual evaluation

After preparing the polyester film according to the Examples and Comparative Examples, the antifogging property of the water film is formed within 10 seconds in the refrigeration of 5 ° C or less or 50 ° C or more steam generation on the surface coated with the antifogging coating solution. It is excellent to form a clear water film as in the example shown in FIG.

Excellent (O): Clear water film formation within 10 seconds.

Poor (X): No clear water film shape within 10 seconds.

(4) Blocking

Two sheets of the polyester film and the CPET (crystalline polyester film) film prepared in Examples and Comparative Examples were overlapped, and pressurized at a temperature of 2 Kgf / cm 2 at 40 ° C. for 1 day, followed by 180 ° Peel Test. . It observed visually whether there was blocking property between films, and evaluated as follows.

Excellent (O): No blocking property.

Poor (X): Blocking property.

(5) Self Vent

The polyester films prepared in Examples and Comparative Examples were overlaid on CPET (crystalline polyester film), and then pressed at 140 ° C. using Heat Gradient (Japan Toyo Seiki) for 1 second at 0.4 MPa pressure for 1 hour at room temperature. Leave it for a while. Peeling the film adhered to a width of 25mm at a speed of 300mm / min using a heat of room temperature ~ 100 ℃ using.

Good (O): Adhesive force less than 100gf / inch in the range of 40 ~ 80 ℃

Poor (X): Adhesive force over 100gf / inch in the range of 40 ~ 80 ℃

Example (1)

1) Preparation of polyurethane primer coating solution (1)

22.5% by weight polyester polyol having a weight average molecular weight of 2000 g / mol, 58.4% of hexamethylene isocyanate, 9.0% by weight of dimethylpropionic acid, and 10.1% by weight of triethylamine, 4% by weight of a polyurethane-based binder and a silicone wetting agent (Methl ( 0.3 wt% of propylhydroxide, ethoxylated) bis (trimethlsiloxy) Silane) was added to water, followed by stirring for 1 hour to prepare a polyurethane coating solution (1).

2) Preparation of Adhesive Layer Coating Liquid (1)

A mixed binder consisting of 5% by weight of a polyester binder having a T _g value of 30 ° C. and 95% by weight of a polyester binder having a T _{g value} of 80 ° C. was mixed with methyl ethyl ketone (MEK): toluene = 1: 1 in a 20% by weight solid. After diluting with 0.5 wt% of colloidal silica particles having a size of 3 μm, the mixture was stirred for about 30 minutes to prepare a coating solution (1) for the adhesive layer.

3) Preparation of antifogging layer coating liquid (1)

Isopropyl alcohol was added to 3% by weight of an edible emulsifier-type antifoaming agent (REKENVITAMIN, REKEMAL A) having a solid content of 40% by weight, and stirred for 30 minutes to prepare a coating solution (1) for the antifogging layer.

4) Preparation of Polyester Film

After the polyethylene terephthalate chip was removed from the moisture in the extruder and melt-extruded, a polyethylene terephthalate sheet having a thickness of 2000㎛ was prepared by quenching and solidifying with a casting drum having a surface temperature of 20 ℃. The prepared polyethylene terephthalate sheet was stretched 3.5 times at 80 DEG C in the machine direction (MD), and then cooled to room temperature. Thereafter, the polyurethane coating solution (1) was coated by a Gravure coating method, and the temperature was increased by 1 ° C. per second to 110 to 150 ° C., followed by preheating and drying, and stretched 3.5 times in the transverse direction (TD). Thereafter, heat treatment was performed at 230 ° C. in a five-stage tenter, and thermally fixed at 10 ° C. in the longitudinal and transverse directions at 200 ° C. to prepare a coated biaxially oriented film. The thickness of the base film was 23 micrometers, and the dry coating thickness of the polyurethane coating layer was 45 nm.

The adhesive layer coating liquid (1) was coated on the polyurethane coating surface by a gravure method, followed by thermal drying at 100 to 150 ° C. in a 5-stage tenter, followed by coating the antifogging layer coating liquid (1) by a gravure method. And heat-drying was carried out at 100 ~ 150 ℃ in a five-stage tenter. Each dry coating thickness was 2.0 micrometers of adhesive layers, and 0.15 micrometer of antifogging coating layers.

The physical properties of the thus obtained polyester film are shown in Table 1 below.

Comparative Example (1)

1) Preparation of Adhesive Layer Coating Liquid (2)

A polyester binder having a T _g value of 80 ° C. was diluted with 20 wt% solids with a MEK: toluene = 1: 1 solvent, 0.5 wt% of 3.0 μm size colloidal silica particles were added, followed by stirring for about 30 minutes to form a coating solution for the adhesive layer. (2) was prepared.

2) Preparation of Polyester Film

After the polyethylene terephthalate chip was removed from the moisture in the extruder and melt-extruded, a polyethylene terephthalate sheet having a thickness of 2000㎛ was prepared by quenching and solidifying with a casting drum having a surface temperature of 20 ℃. The prepared polyethylene terephthalate sheet was stretched 3.5 times at 80 DEG C in the machine direction (MD), and then cooled to room temperature. Thereafter, the polyurethane coating solution (1) prepared in Example 1 was coated by the Gravure coating method, and the temperature was increased by 1 ° C. per second to 110 to 150 ° C. and stretched 3.5 times in the transverse direction (TD) through preheating and drying. Thereafter, heat treatment was performed at 230 ° C. in a 5-stage tenter, followed by heat setting at 10 ° C. in the longitudinal and transverse directions at 200 ° C. to prepare a coated 23 μm biaxially oriented film. The dry coating thickness of the prepared polyurethane coating layer was 45 nm.

After coating the adhesive layer coating solution (2) by the gravure method on the polyurethane coating surface by a gravure method and heat drying at 100 ~ 150 ℃ in a five-stage tenter, the anti-fogging layer coating solution prepared in Example 1 (1 ) Was coated by the gravure method and thermally dried at 100 to 150 ° C. in a 5-stage tenter. Each dry coating thickness was 2.0 micrometers of contact bonding layers, and 0.15 micrometer of antifogging layers.

The physical properties of the thus obtained polyester film are shown in Table 1 below.

Comparative Example (2)

1) Preparation of Adhesive Layer Coating Liquid (3)

A binder containing 100% by weight of a polyester binder having a Tg value of 30 ° C. was diluted with 20% by weight solids with MEK: toluene = 1: 1 solvent, 0.5% by weight of 3.0 μm colloidal silica particles were added, followed by stirring for about 30 minutes. To prepare a coating solution 3 of the adhesive layer.

2) Preparation of Polyester Film

After the polyethylene terephthalate chip was removed from the moisture in the extruder and melt-extruded, a polyethylene terephthalate sheet having a thickness of 2000㎛ was prepared by quenching and solidifying with a casting drum having a surface temperature of 20 ℃. The prepared polyethylene terephthalate sheet was stretched 3.5 times at 80 DEG C in the machine direction (MD), and then cooled to room temperature. Thereafter, the polyurethane coating solution (1) was coated by a Gravure coating method, and the temperature was increased by 1 ° C. per second to 110 to 150 ° C., followed by preheating and drying, and stretched 3.5 times in the transverse direction (TD). Thereafter, heat treatment was performed at 230 ° C. in a 5-stage tenter, followed by heat setting at 10 ° C. in the longitudinal and transverse directions at 200 ° C. to prepare a coated 23 μm biaxially oriented film. The dry coating thickness of the prepared polyurethane coating layer was 45 nm.

The adhesive layer coating solution (3) is coated on the polyurethane coating surface by the gravure method and heat-dried at 100 to 150 ° C. in a 5-stage tenter, followed by coating the antifogging layer coating solution (1) by the gravure method. Then, the thermal drying was carried out at 100 ~ 150 ℃ in a five-stage tenter. Each dry coating thickness was 2 micrometers of contact bonding layers, and 0.15 micrometer of antifogging layers.

The physical properties of the thus obtained polyester film are shown in Table 1 below.

Comparative Example (3)

1) Preparation of Adhesive Layer Coating Liquid (4)

A mixed binder consisting of 50% by weight of a polyester binder having a Tg value of 30 ° C. and 50% by weight of a polyester binder having a Tg of 80 ° C. was diluted with 20% by weight solids with a MEK: toluene = 1: 1 solvent, 0.5 wt% of the colloidal silica particles were added, followed by stirring for about 30 minutes to prepare a coating solution (4) of the adhesive layer.

2) Preparation of Polyester Film

After the polyethylene terephthalate chip was removed from the moisture in the extruder and melt-extruded, a polyethylene terephthalate sheet having a thickness of 2000㎛ was prepared by quenching and solidifying with a casting drum having a surface temperature of 20 ℃. The prepared polyethylene terephthalate sheet was stretched 3.5 times at 80 DEG C in the machine direction (MD), and then cooled to room temperature. Thereafter, the polyurethane coating solution (1) was coated by a Gravure coating method, and the temperature was increased by 1 ° C. per second to 110 to 150 ° C., followed by preheating and drying, and stretched 3.5 times in the transverse direction (TD). Thereafter, heat treatment was performed at 230 ° C. in a 5-stage tenter, followed by heat setting at 10 ° C. in the longitudinal and transverse directions at 200 ° C. to prepare a coated 23 μm biaxially oriented film. The dry coating thickness of the prepared polyurethane coating layer was 45 nm.

After coating the adhesive layer coating solution (4) by the gravure method on the polyurethane coating surface and heat-dried at 100-150 ° C. in a 5-stage tenter, the anti-fogging layer coating solution (1) was continuously coated by the gravure method. Then, the thermal drying was carried out at 100 ~ 150 ℃ in a five-stage tenter. Each dry coating thickness was 2.0 micrometers of contact bonding layers, and 0.15 micrometer of antifogging layers.

The physical properties of the thus obtained polyester film are shown in Table 1 below.

Comparative Example (4)

1) Preparation of Adhesive Layer Coating Liquid (5)

A binder containing 100% by weight of a polyester binder having a Tg value of 30 ° C. was diluted with 20% by weight solids with MEK: toluene = 1: 1 solvent, 0.5% by weight of 1.5 μm size colloidal silica particles were added, followed by stirring for about 30 minutes. To prepare a coating solution 5 of the adhesive layer.

2) Preparation of Polyester Film

After the polyethylene terephthalate chip was removed from the moisture in the extruder and melt-extruded, a polyethylene terephthalate sheet having a thickness of 2000㎛ was prepared by quenching and solidifying with a casting drum having a surface temperature of 20 ℃. The prepared polyethylene terephthalate sheet was stretched 3.5 times at 80 DEG C in the machine direction (MD), and then cooled to room temperature. Thereafter, the polyurethane coating solution (1) was coated by a Gravure coating method, and the temperature was increased by 1 ° C. per second to 110 to 150 ° C., followed by preheating and drying, and stretched 3.5 times in the transverse direction (TD). Thereafter, heat treatment was performed at 230 ° C. in a 5-stage tenter, followed by heat setting at 10 ° C. in the longitudinal and transverse directions at 200 ° C. to prepare a coated 23 μm biaxially oriented film. The dry coating thickness of the prepared polyurethane coating layer was 45 nm.

The adhesive layer coating solution (5) was coated on the polyurethane coating surface by the gravure method and heat-dried at 100 to 150 ° C. in a 5-stage tenter, followed by coating the antifogging layer coating solution (1) by the gravure method. Then, the thermal drying was carried out at 100 ~ 150 ℃ in a five-stage tenter. Each dry coating thickness was 2.0 micrometers of contact bonding layers, and 0.15 micrometer of antifogging layers.

The physical properties of the thus obtained polyester film are shown in Table 1 below.

[Table 1]

As can be seen from the results in Table 1, the higher the content of the binder with a lower T _g , the more easily the physical properties for the adhesive force can be secured. However, as can be seen in Comparative Example (2), when only the binder having a low Tg is used, blocking occurs between the films, which causes a problem when the roll is wound. On the other hand, as can be seen in Comparative Example (1), when only the binder having a high Tg does not cause a blocking problem, but a problem of deterioration of adhesive force occurs. In addition, as can be confirmed in Comparative Example (3), even when two kinds of binders having different Tg are used in combination, the content of the binder having a low Tg is increased to obtain a satisfactory adhesive force. In addition, as confirmed in Comparative Example (3), when the size of the silica particles is reduced, blocking occurs even if all other physical properties are satisfied, which may be a major cause of quality problems.

 Therefore, from the results of Table 1, the polyester film according to the present invention has excellent adhesive strength of 500 gf / inch based on CPET and 700 gf / inch based on APET, and confirms visual evaluation results of forming a water film within 10 seconds or less with a contact angle of 10 ° or less. The anti-fogging performance is also excellent, and the blocking property for the process and the self vent property which prevents the contents from bursting during cooking are also excellent as a result of the adhesive strength falling below 100 gf / inch in the 40 to 80 ℃ section.

  The present invention described above is not limited to the above-described embodiments, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be obvious to him.

10: polyester base film
20: polyurethane primer coating layer
30: Adhesive layer
40: antifogging coating layer

Claims (7)

Polyester base film, the polyurethane-based primer coating layer, the adhesive layer and the anti-fog coating layer is sequentially formed on one surface of the base film,
The adhesive force of the adhesive layer satisfies the following formula 1, the contact angle of the antifogging coating layer satisfies the following formula 2.
[Formula 1]
1500gf / inch ≥ adhesion of adhesive layer ≥ 500gf / inch
[Formula 2]
Contact angle ≤10 ° of antifog coating layer The method according to claim 1,
The adhesive layer may include a polyester-based binder resin in which a first polyester resin having a glass transition temperature of 50 to 80 ° C., a second polyester resin having a glass transition temperature of 0 to 30 ° C., and a filler are included. Ester laminated film. 3. The method of claim 2,
The polyester-based binder resin is a polyester laminated film comprising 5 to 30% by weight of the first polyester resin, and 70 to 95% by weight of the second polyester resin. 3. The method of claim 2,
The filler is a silica particle having an average particle diameter of 0.1 ~ 5㎛, polyester laminate film that is contained in 0.1 to 0.8% by weight. The method according to claim 1,
The anti-fog coating layer is a polyester laminated film that is soluble in water, and includes an edible emulsifier that is solid at room temperature. 6. The method of claim 5,
The emulsifier is polyester laminated film of any one or two or more selected from glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester and lecithin. The method according to claim 1,
The base film has a thickness of 12 ~ 50㎛, the polyurethane primer coating layer has a dry coating thickness of 0.03 ~ 0.1㎛, the adhesive layer has a dry coating thickness of 1 ~ 5㎛, the antifogging coating layer has a dry coating thickness of 0.07 ~ 0.2㎛ Phosphorus laminated film.

Images