KR102382578B1 - Polyester multi-layer film and manufacturing method thereof - Google Patents

Abstract

According to the polyester multilayer film and its manufacturing method according to an embodiment of the present invention, by forming irregularities having a maximum protrusion height (Ry) of 0.1 to 0.5 μm on the surface of the upper skin layer with a mat-type roll, both sides of the polyester multilayer film Both (top and bottom) protrusions (concave-convex) are formed, so even when the top and bottom surfaces of different polyester multilayer films come into contact with each other, anti-blocking properties and slip properties can be secured, and the top surfaces of different polyester multilayer films It is possible to provide a polyester multilayer film that is excellent in anti-blocking properties and slip properties even when in contact with each other or lower surfaces and does not damage transparency.

Description

Polyester multilayer film and manufacturing method thereof

The present invention relates to a polyester multilayer film for packaging, and more particularly, to a polyester multilayer film having excellent anti-blocking properties and slip properties, and a method for manufacturing the same.

Polyester sheet (or polyester multilayer film) has high mechanical strength, chemical resistance and transparency, and has low gas permeability, so it is widely applied to beverage bottles, cosmetic containers, and food trays. Among such polyester sheets, an amorphous polyester sheet called A-PET has excellent processability and is rapidly increasing in use as a packaging material replacing vinyl chloride or polystyrene due to characteristics such as eco-friendliness and food safety. These polyester sheets are not only used as blisters for containers for food and medicines or miscellaneous goods by thermoforming, but also as a clear case for putting cosmetics and electronic devices by taking advantage of their excellent transparency.

In general, a polyester sheet has a problem in that, due to the inherent adhesiveness of the resin, when the polyester sheets are laminated, blocking occurs between the different polyester sheets, thereby reducing the slip property. As a proposal to solve this problem in the prior art, in order to solve the blocking problem that occurs when different polyester sheets are laminated, an anti-blocking agent such as inorganic particles is added to one side of the sheet, or embossing instead of adding an anti-blocking agent The blocking was improved by giving the surface unevenness by processing.

However, if unevenness is provided on only one side of the polyester sheet, blocking in a laminated state can be improved, but blocking between cases sealed with an adhesive after Thompson processing cannot be solved. For example, when a polyester sheet is processed into a predetermined shape to form a packaging container or case, the surface without irregularities is exposed to the outside, and blocking occurs between the surfaces of the case without irregularities, so that between different packaging containers Blocking occurs and the slip property is low, making it difficult for the operator to work. In order to solve this problem, both the upper and lower surfaces of the sheet may be embossed to form irregularities, but transparency may be reduced. In addition, even if all the particles are added to the upper and lower surfaces of the polyester sheet, the particles added to the upper surface of the sheet do not protrude due to the nature of the extrusion process, and thus do not form irregularities on the surface of the polyester sheet, resulting in a blocking phenomenon. As another solution, there is a method of applying a coating film on one surface of the sheet, in which case, unevenness may occur on the exterior of the sheet, and adhesive sealing properties and printability may be deteriorated. In particular, there is a problem that not only blocking when the polyester sheets are laminated, but also blocking occurs between cases sealed with an adhesive after Thompson processing, thereby reducing workability.

Korean Patent Publication No. 10-2019-0055543

The present invention is to solve the above problems, and an object of the present invention is to form irregularities (protrusions) on both sides (top and bottom) of a polyester multilayer film, so that the top and bottom surfaces of different polyester multilayer films are mutually exclusive. It is to provide a polyester multilayer film having excellent anti-blocking properties and slip properties, which can ensure anti-blocking properties and slip properties even when in contact, and has excellent anti-blocking properties and slip properties even when the upper surfaces or lower surfaces of different polyester multi-layer films are in contact with each other.

In addition, it is an object of the present invention to produce a polyester multilayer film, while the lower surface of the sheet is gradually cooled through air cooling in the process of passing through the mirror-type roll to protrude the anti-blocking agent inside, while the upper surface of the sheet is placed on the central mirror-type roll. It is to provide a method of manufacturing a polyester multilayer film capable of solving the problem that the anti-blocking agent does not protrude due to close contact and rapid cooling.

These and other objects and advantages of the present invention will become apparent from the following description of preferred embodiments.

The above object includes a core layer, an upper skin layer formed on the upper surface of the core layer and containing an anti-blocking agent, and a lower skin layer formed on the lower surface of the core layer and containing an anti-blocking agent, the upper skin layer surface being matte It is achieved by a polyester multilayer film having irregularities of 0.1 to 0.5 μm in the maximum projection height (Ry) using a type roll.

Preferably, the surface roughness (Ra) of the upper skin layer may be 0.03 to 0.06 µm, and the surface roughness (Ra) of the lower skin layer may be 0.03 to 0.1 µm.

Preferably, the difference (ΔRa) between the surface roughness (Ra) of the lower skin layer and the upper skin layer may be 0.07 μm or less.

Preferably, the anti-blocking agent may include at least one inorganic particle selected from borosilicate, aluminosilicate, silica and alumina.

Preferably, the anti-blocking agent may have an average particle diameter (D50) of 5.5 to 8 μm, a D90 of 10 to 15 μm, and a D10 of 1.5 to 3.5 μm.

Preferably, the upper skin layer and the lower skin layer may include 0.1 to 0.7 parts by weight of an anti-blocking agent based on 100 parts by weight of the polyester resin.

Preferably, the thickness of the core layer may be 150 to 990 μm, and the thickness of the upper skin layer and the lower skin layer may be 5 to 100 μm.

Preferably, the slip angle at the time of contact between the upper skin layer and the lower skin layer of different polyester multilayer films may be 5 to 30.

Preferably, the slip angle at the time of contact between the upper skin layers of different polyester multilayer films may be 5 to 30.

Preferably, blocking does not occur when pressed at a pressure of 100 kg/cm ² using a press after contact between the upper skin layer and the lower skin layer of the different polyester multilayer films, and the upper skin layer of the different polyester multilayer films Blocking may not occur when pressed with a pressure of 100 kg/cm ² using a press after inter-contact.

Preferably, the haze of the polyester multilayer film may be 4% or less.

Preferably, the upper skin layer and the lower skin layer may further include an organic lubricant for improving slip properties.

Preferably, the organic lubricant may comprise at least one of a fatty acid ester and a fatty acid amide.

In addition, the above object is to prepare a core layer composition comprising a polyester resin, mixing a polyester resin and an anti-blocking agent to prepare an upper skin layer composition and a lower skin layer composition, a core layer composition and an upper skin layer Forming an upper skin layer and a lower skin layer on both sides of the core layer by melt-extruding the composition and the lower skin layer composition through a T-die, and forming irregularities while cooling the upper skin layer using a calender roll It is achieved by a method for producing a polyester multilayer film comprising the steps.

Preferably, in the step of forming the unevenness, the upper skin layer is in contact with the matte roll in a three-stage roll in which a matte-type roll positioned between two mirror-type rolls and a mirror-type roll is disposed adjacently to the upper skin layer It may be to form irregularities in the

Preferably, the uneven height of the mat-type roll may be 0.1 to 0.6 μm, and the surface roughness (Ra) may be 0.03 to 0.07 μm.

Preferably, the surface of the upper skin layer has irregularities with a maximum protrusion height (Ry) of 0.1 to 0.5 µm using a mat-type roll, and the surface roughness (Ra) of the upper skin layer is 0.03 to 0.06 µm, and the lower skin The surface roughness (Ra) of the layer may be 0.03 to 0.1 μm.

According to the polyester multilayer film and its manufacturing method according to an embodiment of the present invention, both surfaces (top and bottom) of the polyester multilayer film are uneven, so that the top and bottom surfaces of different polyester multilayer films are in contact with each other. Anti-blocking properties and slip properties can be secured even in the there is.

In addition, according to the method of manufacturing a polyester multilayer film according to an embodiment of the present invention, by forming predetermined irregularities on the surface of the upper skin layer using a mat-type roll, the lower surface of the sheet is air-cooled in the process of passing through the mirror-type roll The anti-blocking agent inside is cooled slowly through the cooling system, while the upper surface of the sheet is in close contact with the mirror-type roll in the center for rapid cooling, thereby solving the problem that the anti-blocking agent does not protrude.

In addition, according to the polyester multilayer film and its manufacturing method according to an embodiment of the present invention, it is optimized in post-processing operations for manufacturing packaging materials such as printing, Thomson processing, and adhesion, and has high workability.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a cross-sectional view of a polyester multilayer film according to an embodiment of the present invention.
2 is a view for explaining the manufacturing process of the polyester multilayer film according to an embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a polyester multilayer film according to an embodiment of the present invention.
4 is a view taken with a scanning electron microscope (SEM) of the multilayer film prepared through the method of manufacturing the polyester multilayer film of FIG. 3 .

With reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. Throughout the specification, like reference numerals are assigned to similar parts. When a part, such as a layer, film, region, plate, etc., is “on” another part, it includes not only cases where it is “directly on” another part, but also cases where there is another part in between. Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. Also, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

1 is a cross-sectional view of a polyester multilayer film according to an embodiment of the present invention.

Referring to FIG. 1 , the polyester multilayer film according to an embodiment of the present invention includes a core layer 10 , an upper skin layer 20 , and a lower skin layer 30 . In this case, the upper skin layer 20 is formed on the upper surface of the core layer 10 , and the lower skin layer 30 is formed on the lower surface of the core layer 10 . However, in FIG. 1 , the size is enlarged to emphasize the unevenness formed on the surface of the upper skin layer 20 and the anti-blocking agent 40 included in the upper skin layer 20 and the lower skin layer 30 .

The core layer 10 includes a polyester resin. At this time, the polyester resin of the core layer 10 is preferably amorphous polyethylene terephthalate (Amorphous-PET, A-PET), more specifically terephthalic acid (TPA), ethylene glycol (EG) and isopropyl alcohol ( It is preferably formed by condensation polymerization of IPA).

The upper skin layer 20 includes a polyester resin and an anti-blocking agent 40 . In addition, the upper skin layer 20 may further include an organic lubricant for improving slip properties.

In one embodiment, the anti-blocking agent 40 preferably includes at least one inorganic particle selected from borosilicate, aluminosilicate, silica and alumina.

In one embodiment, the anti-blocking agent 40 preferably has an average particle diameter (D50) of 5.5 to 8 μm, D90 of 10 to 15 μm, and D10 of 1.5 to 3.5 μm. If the average particle diameter (D50) of the anti-blocking agent 40 is less than 5.5 μm and D10 is less than 1.5 μm, blocking may occur during loading between sheets, and the average particle diameter (D50) is more than 8 μm, and D90 is 15 μm. If it exceeds, the transparency of the sheet may be deteriorated.

In one embodiment, the upper skin layer 20 preferably includes 0.1 to 0.7 parts by weight of the anti-blocking agent 40 based on 100 parts by weight of the polyester resin. When the amount of the anti-blocking agent 40 is less than 0.1 parts by weight, blocking occurs when loading between sheets, and when it is more than 0.7 parts by weight, the transparency of the sheet is deteriorated.

In this case, the polyester resin of the upper skin layer 20 is preferably amorphous polyethylene terephthalate (A-PET).

In one embodiment, an organic lubricant for improving the slip property of the upper skin layer 20 may be included, and examples of the organic lubricant may be at least one of a fatty acid ester and a fatty acid amide.

In one embodiment, irregularities are formed on the surface of the upper skin layer 20 . In this case, the unevenness formed on the upper skin layer 20 is preferably formed by a matte-type roll.

In general, in the process of forming a polyester multilayer film, a polyester multilayer film is manufactured by passing a melt-extruded resin between a pair of mirror-type rolls and a mirror-type roll positioned between a pair of mirror-type rolls. As such, in the process of passing through the three-tiered mirror-type roll, the lower skin layer is cooled slowly through air cooling, so that the anti-blocking agent in the lower skin layer protrudes to secure anti-blocking properties, and is in close contact with the mirror-type roll in the middle to cool quickly. The upper skin layer does not properly project the anti-blocking agent inside to the upper skin layer surface.

Therefore, in the present invention, as shown in FIG. 2 , irregularities are formed on the surface of the upper skin layer 20 through a pair of mirror-type rolls 201 and 202 and a mat-type roll 203 disposed in the middle of them. to secure anti-blocking properties.

As such, it is preferable that the maximum protrusion height (Ry) of the unevenness formed on the surface of the upper skin layer 20 by the mat-type roll is 0.1 to 0.5 μm. When the maximum protrusion height (Ry) of the irregularities formed on the upper skin layer 20 is less than 0.1 μm, anti-blocking properties and slip properties may be deteriorated in a state in which the sheet is loaded, and between cases sealed with an adhesive after the Thompson and printing process. A blocking problem may also occur, and if the maximum protrusion height Ry of the unevenness formed on the upper skin layer 20 exceeds 0.5 μm, transparency of the sheet may decrease, so it is preferable to set it within the above range.

In one embodiment, the surface roughness (Ra) of the upper skin layer 20 is preferably 0.03 to 0.06㎛. When the surface roughness (Ra) of the upper skin layer 20 is less than 0.03 μm, anti-blocking properties and slip properties may be deteriorated in a state in which the sheet is loaded, and the blocking problem between cases sealed with an adhesive after the Thompson and printing process is also can occur In addition, when the surface roughness Ra of the upper skin layer 20 exceeds 0.06 μm, transparency of the sheet may be reduced.

In one embodiment, the lower skin layer 30 is formed on the lower surface of the core layer 10 and includes a polyester resin and an anti-blocking agent 40 . In addition, the lower skin layer 30 may further include an organic lubricant capable of improving slip properties.

The anti-blocking agent 40 included in the lower skin layer 30 has an average particle diameter (D50) of 5.5 to 8 μm, D90 of 10 to 15 μm, and D10 of 1.5 to 3.5, the same as the upper skin layer 20 . It is preferable that it is micrometer. In addition, the anti-blocking agent 40 included in the lower skin layer 30 preferably includes at least one inorganic particle selected from borosilicate, aluminosilicate, silica, and alumina.

In one embodiment, the lower skin layer 30 preferably includes 0.1 to 0.7 parts by weight of the anti-blocking agent 40 based on 100 parts by weight of the polyester resin. When the amount of the anti-blocking agent 40 is less than 0.1 parts by weight, blocking occurs when loading between sheets, and when it is more than 0.7 parts by weight, the transparency of the sheet is deteriorated. In this case, the polyester resin of the lower skin layer 30 is preferably amorphous polyethylene terephthalate (A-PET).

In one embodiment, the surface roughness (Ra) of the lower skin layer 30 is preferably 0.03 to 0.1㎛. If the surface roughness (Ra) of the lower skin layer 30 is less than 0.03 μm, anti-blocking properties and slip properties may be deteriorated in a state in which the sheet is loaded, and there is also a blocking problem between cases sealed with an adhesive after the Thompson and printing process can occur In addition, when the surface roughness (Ra) of the lower skin layer 30 exceeds 0.1 μm, the transparency of the sheet may be reduced.

In one embodiment, the difference (ΔRa) between the surface roughness (Ra) of the lower skin layer 30 and the upper skin layer 20 is preferably 0.07㎛ or less. When the difference (ΔRa) of the surface roughness (Ra) exceeds 0.07 μm, blocking may occur or the transparency of the sheet may be deteriorated.

In an embodiment, the thickness of the core layer 10 is preferably 150 to 990 μm, and the thickness of the upper skin layer 20 and the lower skin layer 30 is preferably 5 to 100 μm.

In one embodiment, different polyester multilayer films are laminated so that when the upper skin layer and the lower skin layer of the different polyester multilayer films are in contact, the slip angle is preferably 5 to 30, and also the different polyester multilayer films. The slip angle when the upper skin layers are in contact is preferably 5 to 30. If the slip angle is less than 5, the slip property is too strong to cause loading instability when the sheet is loaded, and the loading cross-section may become non-uniform. If the slip angle is more than 30, blocking occurs between the polyester multilayer films.

In one embodiment, the haze of the polyester multilayer film is preferably 4% or less. When the haze of the polyester multilayer film exceeds 4%, transparency is lowered, and there is a problem in that it cannot be used as a clear case.

The polyester multilayer film according to an embodiment of the present invention provides anti-blocking properties to both the upper skin layer 20 and the lower skin layer 30 by forming irregularities on the upper skin layer 20 using a mat-type roll. Therefore, when different polyester multilayer films are laminated and the upper skin layer and lower skin layer of different polyester multilayer films are in contact with each other, blocking does not occur when pressed at a pressure of 100 kg/cm ² using a press. Blocking also does not occur when pressed at a pressure of 100 kg/cm ² using a press after contact between the upper skin layers of the polyester multilayer film.

2 is a view for explaining the manufacturing process of the polyester multilayer film according to an embodiment of the present invention. However, for convenience of explanation, in FIG. 2 , some components including irregularities on the surface of the upper skin layer 20 are enlarged and illustrated.

Referring to FIG. 2 , in the manufacturing process of a polyester multilayer film according to an embodiment of the present invention, a T-Die using a polyester resin raw material as a core layer and a raw material mixed with a polyester resin and an anti-blocking agent as a skin layer It includes the step of melt-extruding through the melt-extrusion and the step of cooling the melt-extruded resin using a calender roll while forming the unevenness. At this time, the calender roll may be composed of a matte-type roll 203 positioned between a pair of mirror-type rolls 201 and 202 .

Conventionally, in the process of passing through the three-tiered mirror-type roll, the lower skin layer 30 of the polyester multilayer film passes through the first mirror-type roll, the second mirror-type roll, and the third mirror-type roll while passing through the second mirror-type roll. Because air cooling is performed without contact with the polyester multilayer film 100, the lower skin layer 30 of the film 100 is gradually cooled, and the anti-blocking agent 40 in the lower skin layer 30 protrudes to secure anti-blocking properties. Surface roughness (Ra) is achieved. On the other hand, the upper skin layer 20 of the polyester multilayer film 100 is cooled rapidly because it is in close contact with the second mirror-type roll, so that the anti-blocking agent 40 inside the upper skin layer 20 is applied to the upper part. It does not protrude properly to the surface of the skin layer 20 . In particular, in the process of the melt-extruded sheet passing between the rolls, the upper skin layer 20 is continuously in close contact with the second mirror-type roll located in the center, and is rapidly compared to the lower skin layer 30 due to the high thermal conductivity of the metal. As it cools down, the anti-blocking agent 40 protrudes from the lower skin layer 30 to the surface of the lower skin layer 30, whereas in the upper skin layer 20, the anti-blocking agent 40 is applied to the upper skin layer ( 20) does not protrude sufficiently to the surface. To solve this problem, in the present invention, irregularities are formed on the surface of the upper skin layer 20 using a matte-type roll 203 positioned between a pair of mirror-type rolls 201 and 202 .

At this time, the height of the unevenness of the mat-type roll 203 is preferably 0.1 to 0.6㎛. When the uneven height of the mat-type roll 203 is less than 0.1 μm, the surface roughness is insufficient to ensure anti-blocking properties and slip properties, and when it exceeds 0.6 μm, the haze increases.

In addition, the surface roughness (Ra) of the mat-type roll 203 is preferably 0.03 to 0.07㎛. If the surface roughness of the mat-type roll is less than 0.03㎛, the maximum protrusion height and surface roughness of the upper skin layer do not reach the standard range, and if it exceeds 0.07㎛, the maximum protrusion height and surface roughness of the upper skin layer are excessive .

As such, if the anti-blocking agent 40 inside the upper skin layer 20 does not protrude, the surface roughness Ra cannot be achieved, and the blocking property is deteriorated unlike the lower skin layer 30 . Accordingly, in the present invention, by forming irregularities on the surface of the upper skin layer 20 using the mat-type roll 203 , the surface roughness that can secure anti-blocking properties to the upper skin layer 20 irrespective of the cooling rate (Ra) can be achieved. Through this structure, the polyester multilayer film according to an embodiment of the present invention achieves anti-blocking properties in both the upper skin layer 20 and the lower skin layer 30, so that when different polyester multilayer films are laminated, the upper When the skin layer 20 and the lower skin layer 30 are in contact with each other or the upper skin layer 20 or the lower skin layer 30 is in contact with each other, anti-blocking properties and slip properties may be secured. Therefore, even if a plurality of packaging containers or cases made by processing a polyester multilayer film are laminated on each other, blocking does not occur between each other and high workability can be achieved.

3 is a flowchart illustrating a method of manufacturing a polyester multilayer film according to an embodiment of the present invention.

Referring to FIG. 3 , the method for manufacturing a polyester multilayer film according to an embodiment of the present invention includes the steps of generating a core layer composition (S301), generating an upper skin layer composition and a lower skin layer composition (S302), and melt-extruding the composition to form an upper skin layer and a lower skin layer on both sides of the core layer (S303) and forming irregularities (S304).

In the step of generating the core layer composition (S301), a core layer composition including a polyester resin is produced. In this case, the polyester resin of the core layer composition is preferably amorphous polyethylene terephthalate (A-PET), and more specifically, by condensation polymerization of terephthalic acid (TPA), ethylene glycol (EG) and isopropyl alcohol (IPA). It is preferable to form It is preferable that the core layer composition consists only of polyester resin.

In the step of generating the upper skin layer composition and the lower skin layer composition (S302), a polyester resin and an anti-blocking agent are mixed to produce a composition. At this time, the polyester resin of the upper skin layer composition and the lower skin layer composition is preferably amorphous polyethylene terephthalate (A-PET), more specifically terephthalic acid (TPA), ethylene glycol (EG) and isopropyl alcohol ( It is preferably formed by condensation polymerization of IPA).

In addition, the anti-blocking agent preferably has an average particle diameter (D50) of 5.5 to 8 μm, D90 of 10 to 15 μm, and D10 of 1.5 to 3.5 μm, and is preferably selected from borosilicate, aluminosilicate, silica and alumina. It is preferred to include at least one inorganic particle.

In addition, the upper skin layer composition and the lower skin layer composition may further include an organic lubricant for improving slip properties.

Next, in the step of melt-extruding the composition to form an upper skin layer and a lower skin layer on both sides of the core layer (S303), the core layer composition, the upper skin layer composition, and the lower skin layer composition are T-die. Through melt extrusion, an upper skin layer and a lower skin layer are formed on both sides of the core layer.

In the step of forming the unevenness ( S304 ), the unevenness is formed on the surface of the upper skin layer using a mat-type roll. More specifically, the melt-extruded resin is melt-extruded on a calender roll composed of a mat-type roll positioned between a pair of mirror-type rolls) and a pair of mirror-type rolls, and the mat-type roll and the upper skin layer are in contact with each other. While cooling, irregularities are formed on the surface of the upper skin layer by the irregular shape of the surface of the mat-type roll.

4 is a view taken with a scanning electron microscope (SEM) of the multilayer film prepared through the method of manufacturing the polyester multilayer film of FIG. 3 . The SEM photograph shown in FIG. 4 is a photograph of the upper skin layer (left) and the lower skin layer (right) of the multilayer film, and it can be seen that irregularities are formed on the surface of the upper skin layer by the mat-type roll.

Hereinafter, the present invention will be described in more detail through examples. The present embodiment is intended to explain the present description in more detail, and the scope of the present invention is not limited to the embodiment.

[ Example ]

[Example 1]

An anti-blocking agent having an average particle diameter (D50) of 7.4 μm, D90 of 12 μm, and D10 of 3.1 μm in 100 parts by weight of the polyester resin in the first extruder to melt-extrusion to form a core layer, and in the second extruder (Borosilicate) 0.4 parts by weight and 0.1 parts by weight of a slip agent (stearyl erucamide) are mixed, melt-extruded to form an upper skin layer and a lower skin layer on the upper and lower surfaces of the core layer, respectively, and the molten resin discharged from the die was passed between the first mirror-type roll and the second mirror-type roll and the mat-type roll positioned therebetween to form irregularities on the surface of the upper skin layer to prepare a polyester multilayer film. In this case, the mat-type roll had an uneven height of 0.4㎛ and a surface roughness of 0.04㎛ was used.

[Example 2]

A polyester multilayer film was prepared in the same manner as in Example 1, except that a matt-type roll having an uneven height of 0.1 μm and a surface roughness of 0.03 μm was used.

[Example 3]

A polyester multilayer film was prepared in the same manner as in Example 1, except that a matt-type roll having an uneven height of 0.6 μm and a surface roughness of 0.07 μm was used.

[Example 4]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the average particle diameter (D50) of the anti-blocking agent was 5.5 μm, D90 was 10 μm, and D10 was 1.5 μm.

[Example 5]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the average particle diameter (D50) of the anti-blocking agent was 8 μm, D90 was 15 μm, and D10 was 3.5 μm.

[Comparative example]

[Comparative Example 1]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the uneven height of the mat-type roll was 9.02 μm and the surface roughness (Ra) was 1.32 μm.

[Comparative Example 2]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the matt-type roll was replaced with a mirror-type roll.

[Comparative Example 3]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the average particle diameter (D50) of the anti-blocking agent was 2.5 μm, D90 was 4.5 μm, and D10 was 1 μm.

[Comparative Example 4]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the average particle diameter (D50) of the anti-blocking agent was 10 μm, D90 was 19 μm, and D10 was 5 μm.

[Comparative Example 5]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the matt-type roll had an uneven height of 0.05 μm and a surface roughness of 0.02 μm.

[Comparative Example 6]

A polyester multilayer film was prepared in the same manner as in Example 1, except that the uneven height of the mat-type roll was 0.7 μm and the surface roughness was 0.08 μm.

Item Example 1 Example 2 Example 3 Example 4 Example 5 matte roll
surface roughness
(μm) Maximum height (Ry) 0.4 0.1 0.6 0.4 0.4 Surface roughness (Ra) 0.04 0.03 0.07 0.04 0.04 anti-blocking agent
Particle size (㎛) D10: 3.1
D50: 7.4
D90: 12 D10: 3.1
D50: 7.4
D90: 12 D10: 3.1
D50: 7.4
D90: 12 D10: 1.5
D50: 5.5
D90: 10 D10: 3.5
D50: 8
D90: 15

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 matte roll
surface roughness
(μm) max height
(Ry) 9.02 - 0.4 0.4 0.05 0.7 surface roughness
(Ra) 1.32 - 0.04 0.04 0.02 0.08 anti-blocking agent
Particle size (㎛) D10: 3.1
D50: 7.4
D90: 12 D10: 3.1
D50: 7.4
D90: 12 D10: 1
D50: 2.5
D90: 4.5 D10: 5
D50: 10
D90: 19 D10: 3.1
D50: 7.4
D90: 12 D10: 3.1
D50: 7.4
D90: 12

For the polyester multilayer films prepared in Examples 1 to 5 and Comparative Examples 1 to 6, physical properties were evaluated through the following experimental examples, and the results are shown in Tables 3 to 5.

[Experimental example]

(1) Haze measurement

Haze was measured by the ASTM D1003 method using a haze meter (COH-400 manufactured by Nippon Denshoku).

(2) Surface roughness measurement

In accordance with JIS 1994, Mitutoyo's SJ-301 measuring instrument was used, and the reference length was set to 0.8 mm and the evaluation length was set to 4 mm. The surface roughness (Ra) of the lower skin layer, the projection height (Ry) and the surface roughness (Ra) of the mat-type roll were measured.

(3) Measurement of slip property (slip angle)

1) Cut the polyester multilayer film to 50mm X 80mm to make two sheets, then stack the cut upper skin layers and the lower skin layers of different polyester multilayer films in contact with each other, and then use HEIDON’s slip measuring device. The angle at which the sheet begins to slide was measured.

2) Cut the polyester multilayer film to 50mm X 80mm to make two sheets, then stack the cut upper skin layers of different polyester multilayer films so that they come into contact with each other, and then use HEIDON’s slippery meter to make the sheet slippery. The starting angle was measured.

(4) Anti-blocking (Press) measurement

1) After cutting the polyester multilayer film into 10 sheets of 100mm X 200mm size, laminate 10 cut polyester multilayer films so that the upper skin layer and the lower skin layer contact, and then press a hydraulic press (200mm X 200mm). After pressing for 5 seconds at 100 kg/cm ² at room temperature using using, the blocking was relatively compared.

2) After cutting the polyester multilayer film into 10 sheets of 100mm X 200mm size, stack 10 cut polyester multilayer films so that the upper skin layers are in contact with each other, and then at room temperature using a hydraulic press (200mm X 200mm). After pressing for 5 seconds at 100kg/cm ² , the blocking was relatively compared.

At this time, the specific lamination method is repeated so that the upper skin layer of the first multi-layer film and the upper skin layer of the second multi-layer film are in contact with each other, and the lower skin layer of the second multi-layer film is in contact with the lower skin layer of the third multi-layer film. to be laminated.

Good: O

Bad: X

(5) Blocking property and slip property sensory test

For two different polyester multilayer films, the upper skin layer and the upper skin layer were stacked on top of each other and then whether slip occurred when the upper sheet was pushed by hand was relatively compared.

Good: O

Bad: X

Item Example 1 Example 2 Example 3 Example 4 Example 5 Haze (%) 2.61 2.3 3.76 1.83 2.9 Sheet
surface roughness
(μm) maximum protrusion height
(Ry) upper skin layer 0.29 0.1 0.5 0.25 0.3 surface roughness
(Ra) upper skin layer 0.04 0.03 0.06 0.03 0.04 lower skin layer 0.05 0.04 0.05 0.03 0.06 anti-blocking
(100kg/cm ² Press) upper skin layer
lower skin layer O O O O O upper skin layer
upper skin layer O O O O O slip property
(slip angle) upper skin layer
lower skin layer 16.87 19.25 16.85 21.5 15.96 upper skin layer
upper skin layer 19.6 25.11 18.2 20 19.4 Blocking/slip sensory test O O O O O

Item comparative example
One comparative example
2 comparative example
3 comparative example
4 comparative example
5 comparative example
6 Haze (%) 5.91 1.8 1.2 4.6 2.2 4.2 Sheet
surface roughness
(μm) maximum protrusion height
(Ry) upper skin layer 3.01 0.2 0.2 0.45 0.07 0.6 surface roughness
(Ra) upper skin layer 0.6 0.02 0.03 0.04 0.02 0.07 lower skin layer 0.04 0.04 0.02 0.07 0.05 0.05 anti-blocking
(100kg/cm ² Press) upper skin layer
lower skin layer O O X O O O upper skin layer
upper skin layer O X O O X O slip property
(slip angle) upper skin layer
lower skin layer 14.5 15.93 22.1 14.8 19.3 16.6 upper skin layer
upper skin layer 18.7 34.95 21 18.7 41 18.14 Blocking/slip sensory test O X O O X O

All of Examples 1 to 5, which are polyester multilayer films according to an embodiment of the present invention, satisfy that the maximum protrusion height of the surface irregularities of the upper skin layer is 0.1 to 0.5 μm and the surface roughness is 0.03 to 0.06 μm, and the lower skin It satisfies that the surface roughness of the layer is 0.03 to 0.1㎛, showing that both anti-blocking properties and slip properties are excellent.

On the other hand, in Comparative Example 1, in which the height and surface roughness of the mat-type roll are excessive, the maximum protrusion height of the surface unevenness of the upper skin layer is excessive and the surface roughness of the upper skin layer is also excessive. It can be seen that there is a problem of increasing

In addition, it can be seen that Comparative Example 2 using a mirror-type roll having almost no surface irregularities rather than a matte-type roll had poor anti-blocking properties and slip properties because irregularities were not formed in the upper skin layer.

In addition, it can be seen that Comparative Example 3 with a small particle diameter of the anti-blocking agent has a blocking problem between the upper skin layer and the lower skin layer because it is difficult for the particles of the lower skin layer to protrude, and Comparative Example 4 with a large particle diameter of the anti-blocking agent can be seen that there is a problem that the haze increases.

In addition, it can be seen that Comparative Example 5, which lacks the uneven height and surface roughness of the mat-type roll, did not secure anti-blocking properties and slip properties between the upper skin layers, and Comparative Example in which the uneven height and surface roughness of the mat-type roll were excessive. 6 shows that there is a problem that the haze is high and transparency is lowered.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

10: core layer 20: upper skin layer
30: lower skin layer 40: anti-blocking agent
201: first mirror-type roll 202: second mirror-type roll
203: matte type roll

Claims (17)

core layer;
an upper skin layer formed on the upper surface of the core layer and including an anti-blocking agent; and
a lower skin layer formed on a lower surface of the core layer and including an anti-blocking agent;
including,
The surface of the upper skin layer is formed with irregularities having a maximum protrusion height (Ry) of 0.1 to 0.5 μm using a mat-type roll,
The anti-blocking agent has an average particle diameter (D50) of 5.5 to 8 μm, D90 of 10 to 15 μm, and D10 of 1.5 to 3.5 μm, a polyester multilayer film. According to claim 1,
The surface roughness (Ra) of the upper skin layer is 0.03 to 0.06 μm, and the surface roughness (Ra) of the lower skin layer is 0.03 to 0.1 μm, a polyester multilayer film. According to claim 1,
The difference (ΔRa) of the surface roughness (Ra) of the lower skin layer and the upper skin layer is 0.07 μm or less, a polyester multilayer film. According to claim 1,
The anti-blocking agent comprises at least one inorganic particle selected from borosilicate, aluminosilicate, silica and alumina, the polyester multilayer film. delete According to claim 1,
The upper skin layer and the lower skin layer comprising 0.1 to 0.7 parts by weight of the anti-blocking agent based on 100 parts by weight of the polyester resin, a polyester multilayer film. According to claim 1,
The thickness of the core layer is 150 to 990㎛, the thickness of the upper skin layer and the lower skin layer is 5 to 100㎛, a polyester multilayer film. According to claim 1,
A polyester multilayer film having a slip angle of 5 to 30 upon contact between the upper skin layer and the lower skin layer of different polyester multilayer films. According to claim 1,
A polyester multilayer film having a slip angle of 5 to 30 upon contact between upper skin layers of different polyester multilayer films. According to claim 1,
After contact between the upper skin layer and the lower skin layer of different polyester multilayer films, blocking does not occur when pressed at a pressure of 100 kg/cm ² using a press,
A polyester multilayer film that does not cause blocking when pressed at a pressure of 100 kg/cm ² using a press after contact between the upper skin layers of different polyester multilayer films. According to claim 1,
The haze of the polyester multilayer film is 4% or less, a polyester multilayer film. According to claim 1,
The upper skin layer and the lower skin layer further include an organic lubricant for improving slip properties. 13. The method of claim 12,
wherein the organic lubricant comprises at least one of a fatty acid ester and a fatty acid amide. Preparing a core layer composition comprising a polyester resin;
preparing an upper skin layer composition and a lower skin layer composition by mixing a polyester resin and an anti-blocking agent;
forming an upper skin layer and a lower skin layer on both sides of the core layer by melt-extruding the core layer composition, the upper skin layer composition, and the lower skin layer composition through a T-die; and
forming irregularities on the upper skin layer while cooling using a calender roll;
includes,
The anti-blocking agent has an average particle diameter (D50) of 5.5 to 8 μm, D90 of 10 to 15 μm, and D10 of 1.5 to 3.5 μm, a method for producing a polyester multilayer film. 15. The method of claim 14,
In the step of forming the unevenness, the upper skin layer comes into contact with the matte roll in a three-stage roll in which a matte-type roll positioned between two mirror-type rolls and a mirror-type roll is adjacently disposed to form the unevenness on the upper skin layer. A method for producing a polyester multilayer film to form a. 16. The method of claim 15,
The height of the unevenness of the mat-type roll is 0.1 to 0.6 μm, and the surface roughness (Ra) is 0.03 to 0.07 μm, the method for producing a polyester multilayer film. 15. The method of claim 14,
The surface of the upper skin layer is formed with irregularities having a maximum protrusion height (Ry) of 0.1 to 0.5 µm using a mat-type roll, and the surface roughness (Ra) of the upper skin layer is 0.03 to 0.06 µm, and the lower skin layer The surface roughness (Ra) of 0.03 to 0.1㎛, the method for producing a polyester multilayer film.

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