KR20140042418A - Polyester film - Google Patents

Abstract

The present invention relates to a polyester film, and specifically, to a polyester film coated with polyurethane which has higher dynamic friction coefficient than existing polyester films and is useful for distributing large size packed goods and displaying products. The polyester film includes: a substrate layer formed of a polyester resin; a polyurethane resin with a glass transition temperature of 30-60°C below zero located on one or both surfaces of the substrate layer; and a coating layer obtained by coating and drying a water base coating composition containing particles and water.

Description

Polyester film {POLYESTER FILM}

The present invention relates to a large packaging film such as pet food, and to a film for preventing slipping when laminating the product in the outermost packaging container.

Recently, as interest in pets increases, the market for large packaged pet food is increasing. In addition, the conversion from wet feed to dry feed is made for reasons such as management or storage.

In the above trend, the packaging material slips during stacking and distribution of large dry packaged pet food for sale, causing problems of distribution and product display. To solve this problem, the outermost layer of packaging requires high friction.

As a patent for compensating for such friction, Korean Patent Publication No. 10-2006-0023733 (March 15, 2006) discloses a first polymer resin layer having a static friction coefficient of 0.6 to 4.5, and a static friction coefficient of the first polymer The polyester laminated | multilayer film containing the 2nd polymer resin layer lower than the static friction coefficient of a resin layer is described.

As described above, the conventional general packaging film has a coefficient of dynamic friction of 0.5 or less in order to ensure fairness in the film production and processing steps. This is not a big problem for small packaged products, but it is a problem in the product display and transportation stage due to slippage of the product in large packages. As a result of research to solve the low friction coefficient problem of the existing general packaging film, the present invention finds that the high friction layer is formed through the in-line coating on the polyester film to ensure the stability in the distribution display process of the product. The present invention was completed.

Korean Patent Publication No. 10-2006-0023733 (2006.03.15)

The present invention has an object to form a high friction layer having a high coefficient of dynamic friction between the film coating surface compared to the existing invention.

The present invention for achieving the above object is as follows.

The present invention is coated with a base layer made of a polyester resin, and an aqueous coating composition including one or both sides of the base layer, a polyurethane-based resin, particles and water having a glass transition temperature of -30 to -60 ° C. It relates to a polyester film comprising a coating layer obtained by drying.

In the present invention, the coating layer may have a dynamic friction coefficient of 0.55 to 1.5.

In the present invention, the particles may be inorganic particles having an average particle diameter of 50 ~ 800nm.

The aqueous coating composition in the present invention is an aqueous emulsion containing water to satisfy the glass transition temperature of 0.1 to 20% by weight, 0.01 to 5% by weight of inorganic particles and 100% by weight of the polyurethane resin having a glass transition temperature of -30 ~ -60 ℃ It may be

In the present invention, the aqueous coating composition may further include 0.01 to 40% by weight of any one or two or more additives selected from emulsifiers, wetting agents and alcohols.

In the present invention, the coating layer may be formed by coating and drying the aqueous coating composition by an inline coating method in the stretching process of the polyester film.

In the present invention, the coating layer may be a dry coating thickness of 10 ~ 500nm.

In the present invention, the polyester base film may be 12 ~ 23㎛ thickness.

In addition, the production method of the polyester film of the present invention

a) melt extruding a polyester resin to prepare a polyester sheet;

b) stretching the polyester sheet in the machine direction;

c) After coating a water-based coating composition containing a polyurethane-based resin, inorganic particles and water having a glass transition temperature of -30 to -60 ° C on one or both sides of the polyester film stretched in the machine direction, stretching in the transverse direction Making;

d) heat setting the biaxially stretched polyester film;

.

In the present invention, the aqueous coating composition may be applied so that the dry coating thickness is 10 to 500nm after stretching.

In another aspect, the present invention relates to a method for producing a polyester film further comprising; d), the step of printing on one side of the substrate layer is not formed high friction layer of the polyester film.

The polyester film according to the present invention has a high coefficient of dynamic friction between the coated surfaces, it is possible to ensure the stability of the product transport and display process.

Hereinafter, the present invention will be described more specifically.

The present invention is an invention for increasing the dynamic friction coefficient of the outermost layer in the conventional packaging film, it is characterized in that the coating layer having a high coefficient of dynamic friction is formed on the polyester film by an in-line coating method.

When the coating layer is applied offline on the PET film, there is a problem that the cost increases because the process is further increased, the cost is increased because the coating thickness is thick. Therefore, the present inventors apply an aqueous coating composition (emulsion) to form a coating layer in the stretching process during the manufacturing process of the PET film by the inline coating method, the coating thickness is thin, not only excellent adhesion to the PET film, The dynamic friction coefficient between the coating layers was found to be very excellent to complete the present invention.

In addition, as a composition for forming a coating layer, it is characterized by using a polyurethane resin having a glass transition temperature of -30 to -60 ° C as a matrix resin forming an aqueous dispersion composition (emulsion), and the dynamic friction coefficient of the resin In order to be excellent, it is characterized by using inorganic particles of various sizes or mixtures thereof as inorganic particles.

In addition, in order to use in an inline process, it must be prepared as an aqueous dispersion composition (emulsion), and a specific composition having excellent water dispersibility by adding a specific wetting agent and dispersion stabilizer to a polyurethane-based resin having a glass transition temperature of -30 to -60 ° C. It is characterized by manufacturing.

A first aspect of the present invention is a coating composition laminated on one surface of the substrate layer made of a polyester resin, and the substrate layer, a polyurethane resin having a glass transition temperature of -30 ~ -60 ℃, inorganic particles and water It is a polyester film containing a coating layer obtained by coating and drying.

According to a second aspect of the present invention, there is provided a coating composition comprising a base layer made of a polyester resin and a polyurethane resin, inorganic particles, and water having a glass transition temperature of -30 to -60 ° C, laminated on both sides of the base layer. Polyester film comprising a coating obtained by coating and drying.

In an aspect of the present invention, the opposite side of the substrate layer on which the coating layer is formed is a polyester film having good printability.

The above aspects are only examples for describing the present invention in detail, and the present invention is not limited thereto.

Hereinafter, the present invention will be described more specifically.

In the present invention, the polyester film may be polyethylene terephthalate, polyethylene naphthalate and the like. More preferably, polyethylene terephthalate having an intrinsic viscosity of 0.6 to 0.7 is preferable because of excellent weather resistance and hydrolysis resistance. In addition, it is preferable that the polyester film has a thickness of 12 to 300 μm and is advantageous in that it can implement various laminated structures.

The present invention forms a coating layer by in-line coating in the process of producing such a polyester film.

The coating layer preferably has a dry coating thickness of 10 to 500 nm and a dynamic friction coefficient of 0.55 to 1.5. If the dry coating thickness is less than 10nm, the coefficient of kinetic friction may be low, and if the dry coating thickness is more than 500nm, the cost is increased, and the adhesiveness may increase, resulting in poor processability.

The water dispersion composition (emulsion) for forming the coating layer is 0.1 to 20% by weight of the polyurethane resin having a glass transition temperature of -30 ~ -60 ℃, inorganic particles 0.01 ~ 20% by weight, additives 0.01 ~ 40% by weight and the rest 100 It is preferable to include water to satisfy the weight percent.

It is preferable to use inorganic particles having an average particle diameter of 50 to 800 nm, and the particles have excellent dynamic friction coefficients in a range of 0.01 to 5 wt%. Examples of the inorganic particles may include silica, calcium carbonate, barium sulfate, titanium dioxide, and the like, but are not limited thereto.

Most preferably, the polyurethane-based resin contains a hydrophilic group, and specifically, a glass transition temperature of -30 to -60 ° C and a dynamic friction coefficient of 0.55 to 1.5 are preferably used. Specific examples of commercialization include, but are not limited to, F-2951D, etc. of Japan Cheil Industries Co., Ltd.

The polyurethane-based resin is preferably used 0.1 to 20% by weight of the total emulsion coating composition, if less than 0.1% by weight may be low coefficient of kinetic friction, when it exceeds 20% by weight, the cost increases, adhesive Since the processability can be reduced by increasing this, it is possible to form a coating layer having the most excellent adhesion in the above range.

The additives may be emulsifiers, wetting agents, alcohols and the like, the content of the additives is preferably used in 0.01 to 40% by weight.

The emulsifier is used to disperse the polyurethane-based resin may be used nonionic, anionic and cationic surfactants, the content of which is preferably 0.01 to 1% by weight of the emulsifier.

The wetting agent is used to uniformly apply the emulsion onto the polyester film, and it is preferable to use one selected from polyethylene glycol, polyethylene ester, modified silicone, etc., since the coating property is greatly improved, for example, for example FO-28, Dow Coatings, and Q2-5212. The content is preferably 0.01 to 0.5% by weight because it is excellent in adhesion.

The alcohol is used to uniformly apply by increasing the wettability, specifically, for example, isopropyl alcohol can be used, it is preferable to use in the range of 1 to 20% by weight.

In addition, if necessary, additives such as UV stabilizers and antistatic agents, which are commonly used in the art, may be further added.

The present invention comprises the steps of melt-extruded polyester resin to make a sheet, uniaxially stretch it, apply a coating composition emulsion and biaxially stretch in the transverse direction to produce a polyester film; To include, imparting printability to the polyester film using a corona treatment machine; As shown in FIG.

More specifically, the method for producing the polyester film of the present invention will be described.

a) melt extruding a polyester resin to prepare a polyester sheet;

b) stretching the polyester sheet in the machine direction;

c) After coating a water-based coating composition containing a polyurethane-based resin, inorganic particles and water having a glass transition temperature of -30 to -60 ° C on one or both sides of the polyester film stretched in the machine direction, stretching in the transverse direction Making;

d) heat setting the biaxially stretched polyester film;

.

Step a) is a process of melting the resin in a cylinder to produce a polyester film into a sheet through a T-die in order to produce a polyester film.

Step b) is a process for producing a polyester film by biaxially stretching the polyester sheet, it is preferable that the stretching in the machine direction using one or more rollers.

Next, in step c), the adhesive layer is formed by the in-line coating method. In this case, it is preferable to use an emulsion that is dispersed to be used for the in-line coating. At this time, the composition of the coating composition for forming the adhesive layer is as described above, it is preferable to apply so that the dry coating thickness after stretching is 10 ~ 500nm. The coating composition is applied to form an adhesive layer, and then stretched in the transverse direction. At this time, it is preferable to use a tenter for lateral stretch.

Next, the process of drying and heat setting to remove moisture used in the coating layer, curing the coating layer, and preventing the film from shrinking.

In addition, corona treatment may be performed on the surface of the polyester film, which is the base layer, before applying the coating composition or before applying the adhesive to bond the functional film, if necessary.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the present invention is not limited to the following examples.

Hereinafter, the physical properties of the present invention were measured as follows.

1) Coefficient of friction

The coefficient of friction between the high friction layer and the corona treated surface between the coating layers of the present invention was evaluated. The measurement method was measured using a Toyoseiki Friction Tester TR instrument to measure the friction coefficient under the conditions of sample width 63 mm X 63 mm, measurement speed 300 mm / min, measurement length 150 mm, sled weight 200g, Load Cell 10N.

[Example 1]

Preparation of Coating Composition (1)

1% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and 300 nm silica particles with an average particle diameter of 20% by weight An aqueous solution, SS-300) 0.1% by weight and the balance of water was mixed to prepare a coating composition (1).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 1 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

[Example 2]

Preparation of Coating Composition (2)

1% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and 300 nm silica particles with an average particle diameter of 20% by weight Aqueous solution, SS-300) 0.3% by weight and the balance of water to prepare a coating composition (2).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 2 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

[Example 3]

Preparation of Coating Composition (3)

1% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and 300 nm silica particles with an average particle diameter of 20% by weight Aqueous solution, SS-300) 0.5% by weight and the balance of water to prepare a coating composition (3).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 3 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

Example 4

Preparation of Coating Composition (4)

1% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin with a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and 140 nm silica particles with an average particle diameter of 20% by weight Aqueous solution, SS-140) 0.3% by weight, average particle diameter 800nm silica particles (solid content 10% by weight aqueous solution, SX8745-08) 0.1% by weight and the remaining amount of water was mixed to prepare a coating composition (4).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 4 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

[Example 5]

Preparation of Coating Composition (5)

1% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and an average particle size of 800 nm silica particles (solid content of 10% by weight) Aqueous solution, SX8745-08) 0.1% by weight and the balance of water to prepare a coating composition (5).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 5 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

[Example 6]

Preparation of Coating Composition (6)

1% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and an average particle size of 800 nm silica particles (solid content of 10% by weight) Aqueous solution, SX8745-08) 0.2% by weight and the balance of water to prepare a coating composition (6).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 6 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

[Example 7]

Preparation of Coating Composition (7)

1.5% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane-based resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and an average particle diameter of 450 nm silica particles (solid content of 10% by weight) Aqueous solution, MP-4540) 0.3% by weight and the balance of water to prepare a coating composition (7).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 7 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 150 nm.

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

[Example 8]

Preparation of Coating Composition (8)

2% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane resin with a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and a silica particle with an average particle diameter of 450 nm (10% by weight of solid content) Aqueous solution, MP-4540) 0.4 wt% and the balance of water to prepare a coating composition (8).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 8 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 200 nm.

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

[Example 9]

Preparation of Coating Composition (9)

1.5% by weight of F-2951D from Japan Cheil Industries, Ltd., a polyurethane-based resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 from Dow Corning), and an average particle diameter of 450 nm silica particles (solid content of 10% by weight) Aqueous solution, MP-4540) 0.4 wt% and the balance of water to prepare a coating composition (9).

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 9 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 150 nm.

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

[Comparative Example 1]

Preparation of Coating Composition (10)

Coating composition (10) by mixing 1% by weight of F-2951D of Japan Cheil Industries, Ltd., a polyurethane-based resin having a glass transition temperature of -50 ° C, 0.25% by weight of a wetting agent (Q2-5210 of Dow Corning) and the remaining amount of water (10) Was prepared.

Preparation of Polyester Film for Back Sheet

A polyethylene terephthalate chip having a moisture content of 100 ppm or less was injected into a melt extruder, melted, and then extruded through a T-die, followed by quenching and solidifying with a casting drum having a surface temperature of 20 ° C. to prepare a polyethylene terephthalate sheet having a thickness of 2000 μm. .

The prepared polyethylene terephthalate sheet was stretched 3.5 times in the machine direction (MD) at 110 ° C. and then cooled to room temperature. Thereafter, the coating composition 10 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) through preheating and drying at 140 ° C. Thereafter, heat treatment was performed at 235 ° C. in a 5-stage tenter, followed by heat setting by relaxing 10% in the machine direction and the transverse direction at 200 ° C. to prepare a 12 μm biaxially oriented film having an adhesive layer formed on one surface thereof. The dry coating thickness after extending | stretching the said contact bonding layer was 100 nm.

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

[Table 1]

As shown in the table, it can be seen that the inclusion of the inorganic particles of the embodiment including the coating layer according to the present invention has a significantly high coefficient of friction.

However, in Comparative Example 1 without inorganic particles, it was found that the friction coefficient was low. As shown in the examples, the size of the particles should be greater than or equal to a certain size and should include a certain amount or more.

Claims (11)

Obtained by coating and drying a base layer made of a polyester resin and an aqueous coating composition including one or both sides of the base layer and a polyurethane-based resin, particles, and water having a glass transition temperature of -30 to -60 ° C. Polyester film comprising a coating layer. The method according to claim 1,
The coating layer has a dynamic friction coefficient of 0.55 ~ 1.5 polyester film. The method according to claim 1,
The particles are polyester film is an inorganic particle having an average particle diameter of 50 ~ 800nm. The method according to claim 1,
The water-based coating composition is a polyester water-based emulsion containing water so as to satisfy 0.1 to 20% by weight of polyurethane-based resin, 0.01 to 5% by weight of inorganic particles, and 100% by weight of a glass resin having a temperature of -30 to -60 ° C. film. 5. The method of claim 4,
The aqueous coating composition further comprises 0.01 to 40% by weight of any one or two or more additives selected from emulsifiers, wetting agents and alcohols. The method according to claim 1,
The coating layer is a polyester film is formed by coating and drying the aqueous coating composition by the in-line coating method in the stretching process of the polyester film. The method according to claim 1,
The coating layer is a polyester film excellent in coefficient of friction of 10 ~ 500nm dry coating thickness. The method according to claim 1,
The polyester base film is a polyester film having a thickness of 12 ~ 23㎛. a) melt extruding a polyester resin to prepare a polyester sheet;
b) stretching the polyester sheet in the machine direction;
c) After coating a water-based coating composition containing a polyurethane-based resin, inorganic particles and water having a glass transition temperature of -30 to -60 ° C on one or both sides of the polyester film stretched in the machine direction, stretching in the transverse direction Doing;
d) heat setting the biaxially stretched polyester film;
Method for producing a polyester film comprising a. 10. The method of claim 9,
The aqueous coating composition is a method of producing a polyester film to be applied so that the dry coating thickness after stretching 10 ~ 500nm. 10. The method of claim 9,
After the step d), e) printing on one surface of the base layer on which the high friction layer of the polyester film is not formed; manufacturing method of a polyester film further comprising.