TW202227542A - Polyester film structure - Google Patents

Abstract

The polyester film structure according to an exemplary embodiment comprises: a polyester resin layer having a first surface and a second surface facing each other; and an organic particle dispersed in the polyester resin layer. The second surface corresponds to a release coating surface, and an indentation modulus measured on the second surface using a nanoindenter is less than 4 GPa. The polyester film structure can be used as a release film substrate for the green sheet forming process to improve process stability and reliability.

Description

polyester film structure

The present invention relates to a polyester film structure. More specifically, it relates to a polyester film structure including a resin layer and particles dispersed in the resin layer.

In the manufacturing process of electronic devices such as multilayer ceramic capacitors (MLCC), a release film can be used as a carrier film for intermediate processes such as heat treatment. For example, before firing, a firing process and/or a molding process is performed while the laminate including the ceramic layer is moved on the release film in a green sheet state.

For example, a release film comprising a polyester substrate can be used as the carrier film. The release film is preferably designed to be easily peeled from the green sheet that has undergone the molding process without causing physical and mechanical deformation to the green sheet during the process.

Meanwhile, with the recent size reduction of MLCCs, the thickness of green sheets is also getting thinner. Therefore, the surface roughness of the polyester base material is easily transferred to the green sheet to cause deformation. However, when the surface roughness is excessively reduced, the ease of fabrication, such as the sticking phenomenon, is deteriorated.

Therefore, it is necessary to design a release film that can improve the reliability of process objects such as green sheets while reducing process defects.

For example, Korean Granted Patent No. 10-1976118 and the like disclose a release film for manufacturing a green sheet.

[Prior Art Literature]

[Patent Literature]

Korean Patent Gazette No. 10-1976118

It is an object of the present invention to provide a polyester release film structure that provides improved mechanical reliability and process stability.

A polyester film structure according to an exemplary embodiment includes: a polyester resin layer having first and second surfaces facing each other; and particles dispersed in the polyester resin layer. The second surface corresponds to the release coating surface on which the indentation modulus measured using a nanoindenter is less than 4 GPa.

In some embodiments, the polyester resin layer may include a first resin layer having the first surface and a second resin layer having the second surface. The particles may include first particles dispersed in the first resin layer and second particles dispersed in the second resin layer, and the first particles and the second particles may be organic particles.

In some embodiments, the thickness of the second resin layer may be more than 10 μm.

In some embodiments, the first particles may have a larger particle size than the second particles.

In some embodiments, the content of the first particles in the first resin layer may be greater than the content of the second particles in the second resin layer.

In some embodiments, the content of the first particles in the first resin layer may be 0.4 to 1 wt %, and the content of the second particles in the second resin layer may be 0.1 to 0.3 wt %.

In some embodiments, the difference in centerline average roughness (Ra) on the first surface and the second surface may be 5 nm or more.

In some embodiments, the difference in centerline average roughness (Ra) on the first surface and the second surface may be 5 to 20 nm.

In some embodiments, the difference in maximum peak height surface roughness (Rp) of the first surface and the second surface may be greater than 70 nm.

In some embodiments, the indentation modulus measured on the second surface using a nanoindenter may be greater than 2 GPa and less than 4 GPa.

A polyester film structure according to an exemplary embodiment includes: a first layer including a first resin layer and first particles dispersed in the first resin layer; and a second layer laminated on the first layer and includes a second resin layer and second particles dispersed in the second resin layer. The difference between D ₉₀ and D ₁₀ in the particle size distribution of the first particles is 500 nm or less, and the sum of the ten-point average roughness (Rz) of the first layer and the second layer is 200 nm or more.

In some embodiments, the difference between D ₉₀ and D ₁₀ of the first particle may be in the range of 100 to 400 nm.

In some embodiments, the first particles may include two or more particles of different particle sizes or materials.

In some embodiments, the difference in particle size ( _D50 ) between the two particles included in the first particle may be 300 nm or less.

In some embodiments, the sum of the ten-point average roughness (Rz) of the first layer and the second layer may be in the range of 200 to 500 nm.

In some embodiments, the surface of the first layer can be used as a process execution surface and the surface of the second layer can be used as a release coating surface.

A polyester film structure according to an exemplary embodiment includes: a first layer including a first resin layer and first particles dispersed in the first resin layer; and a second layer laminated on the first layer and includes a second resin layer and second particles dispersed in the second resin layer. The sum of the ten-point average roughness (Rz) of the first layer and the second layer is in the range of 200 to 500 nm, and the sum of the centerline average roughness (Ra) of the first layer and the second layer is in the range of 200 to 500 nm. in the range of 10 to 30 nm.

In some embodiments, the Ra and Rz of the second layer may be less than the Ra and Rz of the first layer, respectively, and the maximum peak height surface roughness (Rp) of the second layer may be 100 nm or less.

In some embodiments, the particle size (D ₅₀ ) of the second particles is smaller than the particle size (D ₅₀ ) of the first particles, and the first particles may include two or more particles of different particle sizes or materials.

In some embodiments, the sum of the ten-point average roughness (Rz) of the first layer and the second layer is in the range of 200 to 400 nm, and the centerline average roughness of the first layer and the second layer The sum of (Ra) can be in the range of 15 to 25 nm.

According to an exemplary embodiment, deformation due to pressing of the green sheet can be suppressed by adjusting the indentation modulus of the release surface of the polyester film structure.

In some embodiments, the polyester film structure may use organic particles including, for example, a cross-linked polystyrene resin as the particles for forming the surface roughness. Therefore, low surface roughness can be achieved more easily than in the case of using inorganic particles. In addition, as the process execution surface, the surface roughness can be relatively increased. Therefore, both the winding stability and the process stability can be improved.

According to exemplary embodiments, the aforementioned low surface roughness/process stability can be achieved by using The particles are achieved together by adjusting the surface roughness difference between the release coating surface and the process execution surface to a predetermined range.

According to other exemplary embodiments, the polyester film structure may have a multi-layer structure including a first layer having a process execution surface and a second layer having a release coating surface. The difference between D ₉₀ and D ₁₀ of the particles contained in the second layer may be adjusted to be within a predetermined range, thereby improving roughness uniformity while maintaining a predetermined surface roughness. Therefore, both the winding stability and the process stability can be improved by the first layer.

According to an exemplary embodiment, by maintaining the sum of the roughnesses of the first layer and the second layer within a predetermined range, low surface roughness by the second layer and process stability by the second layer can be simultaneously achieved improvement.

In some embodiments, the second layer may include two or more organic particles having different particle sizes. Therefore, even when the roughness is relatively increased due to the elasticity of the organic particles, deformation of an object such as MLCC can be suppressed, and sufficient process stability can be ensured.

100: polyester film structure

100a: first surface

100b: Second surface

110: first floor

112: The first resin layer

114: The first particle

120: Second floor

122: Second resin layer

124: Second particle

1 is a schematic cross-sectional view illustrating a polyester film structure according to an exemplary embodiment.

Exemplary embodiments disclosed in the present application provide a polyester release film structure including a polyester resin layer and particles.

Hereinafter, embodiments of the present invention will be described in detail. However, since the present invention can have many Such variations may take many forms, thus specific embodiments are shown in the drawings and described in detail herein. It is not intended, however, to limit the invention to the particular form disclosed, but it should be understood to include all modifications, equivalents, and substitutes within the spirit and scope of the invention.

Unless otherwise defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Terms such as those defined in common dictionaries should be interpreted as having meanings consistent with the context of the related art, and should not be interpreted in ideal or overly formal meanings unless explicitly defined in this application.

FIG. 1 is a schematic cross-sectional view illustrating a polyester release film structure according to an exemplary embodiment.

1 , a polyester film structure 100 (hereinafter, may be abbreviated as a film structure) according to an exemplary embodiment may include a resin layer and particles dispersed in the resin layer.

In some embodiments, the membrane structure 100 may have a multilayer structure including two or more layers. For example, as shown in FIG. 1 , the membrane structure 100 may include a first layer 110 and a second layer 120 laminated on the first layer 110 .

The first layer 110 may include a first resin layer 112 and first particles 114 dispersed in the first resin layer 112 . The second layer 120 may include a second resin layer 122 and second particles 124 dispersed in the second resin layer 122 .

The membrane structure 100 may include a first surface 100a and a second surface 100b. For example, the first surface 100a and the second surface 100b may correspond to the lower surface and the upper surface of the membrane structure 100, respectively.

According to an exemplary embodiment, the second surface 100b may correspond to a release coating surface. For example, a release coating such as a silicon release layer may be formed on the second surface 100b, and a multilayer ceramic capacitor (MLCC) green sheet may be laminated. The second surface 100b may be provided by the top surface of the second layer 120 .

The first surface 100a may be a process execution surface that moves while being in contact with a conveying device of a green sheet firing/forming device. The first surface 100a may be provided by the bottom surface of the first layer 110 .

The first resin layer 112 and the second resin layer 122 may include polyester resin. The polyester resin can be prepared by polycondensation of an aromatic diacid-based compound and a diol-based compound.

Examples of aromatic dicarboxylic acids include dimethyl terephthalate, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, cyclobutane dicarboxylic acid, cyclohexane dicarboxylic acid, 5-sulfoisophthalic acid 5-sulfo isophthalic acid, 5-sulfo propoxy isophthalic acid, diphenyl dicarboxylic acid, diphenoxy alkane dicarboxylic acid (diphenoxy alkane dicarboxylic acid), adipic acid, sebacic acid, and the like. Preferably, dimethyl terephthalate or terephthalic acid can be used.

Examples of glycol compounds include ethylene glycol, 1,3-propanediol, alkylene glycol compounds such as 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,4 - Cyclohexanedimethanol, etc. Preferably, ethylene glycol can be used.

According to exemplary embodiments, the first particles 114 and the second particles 124 may include organic particles or inorganic particles.

The organic particles may include cross-linked organic resin particles, for example, silicone resin, cross-linked divinyl benzene polymethacrylate, cross-linked polymethacrylate, cross-linked polystyrene resin, benzoguanamine may be used -Formaldehyde resin, benzoguanamine-melamine-formaldehyde resin, melamine-formaldehyde resin, etc.

Inorganic particles may include, for example, silicon dioxide ( _SiO2 ), titanium dioxide ( _TiO2 ), zeolite, barium sulfate, calcium carbonate, and the like.

According to some embodiments, the first particles 114 and the second particles 124 may be the above-mentioned organic particles.

In one embodiment, the first particles 114 and the second particles 124 may include cross-linked polystyrene (PS) resin. For example, the first particles 114 and the second particles 124 may include spherical polystyrene resin particles.

The surface roughness can be achieved on the surfaces (the first surface 100a and the second surface 100b) of the film structure 100 by the particles 114 and 124 contained in the resin layers 112 and 122. As described above, according to exemplary embodiments, the organic particles 114 and 124 including, for example, a cross-linked polystyrene resin may be used as the particles for forming the surface roughness.

In this case, a low surface roughness can be achieved or maintained relatively easily compared to the case of using inorganic particles such as silicon dioxide (SiO ₂ ), titanium dioxide (TiO ₂ ), zeolite, barium sulfate, calcium carbonate, and the like. Therefore, for example, even when the thickness of the MLCC green sheet laminated on the second surface 100b as the release coating surface is reduced, process defects due to transfer of surface roughness can be suppressed.

Furthermore, since organic particles having lower surface hardness and elasticity are used as the first particles 114 and the second particles 124, the transfer of stress to the green sheet can be suppressed even under the same surface roughness. Therefore, for example, for the first surface 100a corresponding to the process execution surface, a margin for relatively increasing the surface roughness can be ensured.

Therefore, the process operability and process control characteristics by the first surface 100a can be ensured. In addition, when the film structure 100 is provided in a rolled state, the winding stability and anti-blocking properties can be improved by the first surface 100a having a relatively high roughness.

In addition, organic particles such as polystyrene resin particles may have excellent affinity with organic compounds used to form the resin layers 112 , 122 . Therefore, the particles 114, 124 are more uniformly dispersed In the resin layers 112, 122, the uniformity of the surface roughness can thus be improved.

In some embodiments, the second layer 120 may be substantially free of the inorganic particles described above. In addition, the first layer 110 may substantially not include the above-mentioned inorganic particles.

In one embodiment, the second layer 120 and/or the first layer 110 further includes a trace amount of inorganic particles (eg, a content of 0.05 wt % or less) within a range that does not impair the effect by using the above-described organic particles 114 and 124 .

In some embodiments, the second particles 124 included in the second layer 120 may include inorganic particles such as silica, and the first particles 114 included in the first layer 110 may include organic particles such as PS resin particles.

For example, when the polyester resin is synthesized, the first particles 114 and the second particles 124 may be added in the form of a slurry dispersed in a glycol-based compound such as ethylene glycol.

In an exemplary embodiment, the indentation modulus measured on the release coating surface or the second surface 100b using a nanoindenter may be less than 4 GPa. Within the above range, the pressing strength by the second surface 100b is reduced, so that the occurrence of stress on the green sheet and pressing can be effectively suppressed.

Preferably, the indentation modulus measured on the release coating surface or the second surface 100b using a nano-indenter may be greater than 2GPa and less than 4GPa, more preferably greater than 3GPa and less than 4GPa. Within the above range, deformation due to pressing of the green sheet can be prevented by the film structure 100 without reducing process stability and mechanical stability.

In some embodiments, the thickness of the second layer 120 may be greater than about 10 μm. In this case, the second layer 120 is provided as a release layer, and may also be sufficiently provided as, for example, an elastic layer. For example, the thickness of the second layer 120 may be in the range of about 10 to 40 μm.

In other exemplary embodiments, the first particles 114 included in the first layer ₁₁₀ may include a plurality of particles having different particle sizes (eg, different D50s from each other). Therefore, the dispersibility of the organic particles in the first resin layer 112 can be further improved to further improve the uniformity of the overall surface roughness on the first surface 100a.

When the first particles 114 include a plurality of particles having different particle sizes, the difference between D ₉₀ and D ₁₀ in the particle size distribution of the first particles 114 may be about 500 nm or less. When the difference between D ₉₀ and D ₁₀ is greater than about 500 nm, the particle size distribution deviation is too large, resulting in reduced roughness uniformity, which can reduce the winding stability of the film structure 100, and can cause film wrinkling and blocking.

Preferably, the difference between _D90 and _D10 of the first particles 114 may be about 50 to 500 nm, more preferably about 100 to 400 nm. Within the above range, sufficient winding stability and roughness uniformity can be improved.

The _D90 and _D10 values can be measured by means of a particle size analyzer from the cumulative distribution curve of the powder.

As described above, the first particles 114 included in the first layer 110 may include a mixture or blend of two or more particles having different particle sizes. In some embodiments, the particle size difference (eg, _D50 difference) between different particles in the mixture can be about 300 nm or less. Within the above range, defects (eg, partial wrinkling, partial tearing, green sheet pressing, etc.) due to uneven film properties due to increased particle size differences can be prevented.

Preferably, the particle size difference between particles different from each other can be adjusted to be in the range of about 100 to 300 nm.

According to an exemplary embodiment, with the above-described particle size design of the first particles 114, deformation, pressing, etc. of the green sheet can be prevented while relatively increasing the surface roughness on the first surface 100a.

In some embodiments, the second particles 124 included in the second layer 120 may include There are multiple particles of different particle sizes. As described above, the first particles 114 included in the first layer 110 may include a plurality of particles having different particle sizes. Therefore, the dispersibility of the organic particles in each layer can be further improved, thereby further improving the uniformity of the surface roughness.

According to some embodiments, the particle size (eg, D ₅₀ ) of the first particles 114 may be greater than or equal to the particle size (eg, D ₅₀ ) of the second particles 124 . Preferably, the particle size of the first particles 114 may be larger than the particle size of the second particles 124 .

For example, the second surface 100b of the second layer 120 may be provided as a release coating surface and a lamination surface of the MLCC green sheet as described above. Therefore, the particle size of the second particles 124 may be smaller than the particle size of the first particles 114 .

In some embodiments, the particle size of the first particles 114 may be about 0.3 to 1.5 μm. Preferably, the particle size of the first particles 114 may be about 0.3 to 1 μm, more preferably about 0.3 to 0.6 μm.

In some embodiments, the particle size of the second particles 124 may be about 0.05 to 0.3 μm. Preferably, the particle size of the second particles 124 may be about 0.1 to 0.3 μm.

According to example embodiments, the content of the first particles 114 in the first layer 110 may be greater than or equal to the content of the second particles 124 in the second layer 120 . Preferably, the content of the first particles 114 may be greater than that of the second particles 124 .

In some embodiments, the content of organic particles 114 and 124 in membrane structure 100 may be about 0.1 to 1 wt %. In one embodiment, the content of the first particles 114 in the first layer 110 may be about 0.4 to 1 wt %, and the content of the second particles 124 in the second layer 120 may be about 0.1 to 0.3 wt %.

In some embodiments, for example, the content of the first particles 114 in the first layer 110 may be about 2,000 to 5,000 ppm, and the content of the second particles 124 in the second layer 120 may be about 1,000 to 5,000 ppm 2,000ppm.

According to an exemplary embodiment, the first particles 114 have a larger particle size than the second particles 124 , or the content of the first particles 114 in the first layer 110 may be greater than the content of the second particles 124 in the second layer 120 . Therefore, by relatively increasing the surface roughness on the first surface 100a, the winding stability and anti-blocking properties can be improved.

In some embodiments, the surface roughness (eg, Ra and Rz) of the first surface 100a of the membrane structure 100 may be greater than the surface roughness of the second surface 100b. Therefore, by realizing low roughness on the second surface 100b on which the MLCC green sheet is laminated, the transfer of the roughness to the green sheet can be prevented, and the deformation of the green sheet can be prevented.

In addition, by relatively increasing the surface roughness of the first surface 100a, the process operability and process control characteristics by the first surface 100a can be ensured. When the film structure 100 is provided in a rolled state, the winding stability and anti-blocking properties can also be improved by the first surface 100a having a relatively high roughness.

According to some embodiments, the difference between the centerline average roughness Ra of the first surface 100a and the second surface 100b of the film structure 100 may be 5 nm or more. Within the above range, it is possible to ensure sufficient process stability and blocking resistance by the process-performing surface while maintaining a low surface roughness on the surface of the release coating.

In one embodiment, the difference between the centerline average roughness Ra of the first surface 100a and the second surface 100b of the film structure 100 may be 5 to 20 nm, preferably in the range of 5 to 15 nm.

According to other exemplary embodiments, the sum of the centerline average roughness Ra of the first surface 100a and the second surface 100b may be in a range of about 10 to 30 nm. In addition, the sum of the ten-point average roughness Rz of the first surface 100a and the second surface 100b is about 200 nm or more, and in one embodiment , can be in the range of 200 to 500 nm.

By keeping the sum of the surface roughnesses of the first surface 100a and the second surface 100b within the above-mentioned range, while suppressing deformation of the green sheet due to an excessive increase in the total roughness value, it is possible to suppress when the total roughness value excessively decreases. The blocking phenomenon that occurs during the time, the peeling defect of the green sheet, etc.

Therefore, by considering the roughness control in each resin layer and the sum of the total roughness, the defect suppression of the green sheet can be controlled more effectively and process stability can be ensured.

In a preferred embodiment, the sum of the centerline average roughness Ra of the first surface 100a and the second surface 100b may be in the range of about 15 to 25 nm. Further, the sum of the ten-point average roughnesses Rz of the first surface 100a and the second surface 100b may be in the range of about 200 to 400 nm, and in one embodiment, may be in the range of about 200 to 300 nm.

For example, the average roughness Ra of the centerline of the second surface 100b may be in the range of about 3 to 10 nm. The centerline average roughness Ra of the first surface 100a may be in the range of about 10 to 25 nm, preferably in the range of about 10 to 20 nm.

In one embodiment, the ten-point average roughness Rz of the second surface 100b may be in the range of about 50 to 150 nm. The ten-point average roughness Rz of the first surface 100a may be about 150 to 250 nm.

In some embodiments, the maximum peak height surface roughness Rp of the first surface 100a may be greater than the maximum peak height surface roughness Rp of the second surface 100b.

In some embodiments, the difference in maximum peak height surface roughness Rp of the first surface 100a and the second surface 100b may be greater than about 70 nm. Preferably, the difference in maximum peak height surface roughness (Rp) of the first surface 100a and the second surface 100b may be in the range of about 70 to 180 nm.

For example, sufficient process stability and blocking resistance can be ensured by the process execution surface while maintaining a low surface roughness on the release coating surface within the above-mentioned surface roughness range.

In some embodiments, the maximum peak height surface roughness Rp of the first surface 100a may exceed about 100 nm. The maximum peak height surface roughness Rp of the second surface 100b may be about 100 nm or less.

For example, the maximum peak height surface roughness Rp of the first surface 100a may be in the range of about 130 to 250 nm. The maximum peak height surface roughness Rp of the second surface 100b may be in the range of about 40 to 70 nm.

In addition, by controlling the overall roughness value of the film structure 100 within the above-mentioned range, process stability can be managed with higher reliability.

For example, the film structure 100 may be fabricated by co-extrusion. For example, the organic particle-dispersed polyester resins used to form the first layer 110 and the second layer 120 are dried, melted, and extruded, respectively, and then may be joined by a die (eg, a multi-manifold die or a feedblock die) polyester resin. Thereafter, a sheet can be formed by a casting process, and the membrane structure 100 can be obtained by a stretching process.

As described above, the film structure 100 according to the exemplary embodiment can be used as a release film substrate for performing a green sheet forming process. For example, a solvent-based silicone resin may be coated on the second surface 100b of the film structure 100 to form a release film by thermal drying.

Below, preferred embodiments are used to help understand the present invention, but these embodiments are only used to illustrate the present invention, do not limit the scope of the appended claims, and are obvious to those skilled in the art. Yes, various changes and modifications of the embodiments can be made within the scope and spirit of the present invention, and such changes and modifications certainly fall within the scope of the appended claims.

Examples and Comparative Examples

Example 1

A polystyrene/ethylene glycol first slurry having a concentration of 20% by weight was prepared by dispersing polystyrene (PS) particles having an average particle size of 0.1 μm in ethylene glycol. Further, polystyrene particles having an average particle diameter of 0.5 μm were dispersed to prepare a polystyrene/ethylene glycol second slurry having a concentration of 20% by weight, respectively.

Dimethyl terephthalate and slurry are mixed in an equivalent ratio of 1:2 respectively, and then a general transesterification catalyst is added to carry out transesterification. A general polycondensation catalyst was added to complete the polycondensation reaction to prepare a polyester mixed resin with an intrinsic viscosity of 0.62 dl/gr. Thus, a first polyester mixed resin and a second polyester mixed resin containing polystyrene particles having particle sizes of 0.1 μm and 0.5 μm, respectively, were prepared.

The polyester mixed resin prepared above is dried, melted and extruded according to the manufacturing method of the co-extruded polyester film, and then joined by a feeding block die, and cast on a grinding drum at room temperature to form a sheet. form.

The formed sheet was stretched at a longitudinal stretch ratio of 3.4 times and a transverse stretch ratio of 3.5 times while being heated at 80° C. to prepare a polyester base film having a thickness of 30 μm. The first layer formed of the first polyester mixed resin and the second layer formed of the second polyester mixed resin were formed to have a thickness of 15 μm, respectively.

Example 2 to Example 7

A polyester base film was prepared in the same manner as in Example 1 except that the particle composition (particle size, content, etc.) was changed as described in Table 1.

Example 8

1) Preparation of the second layer of resin

A silica particle slurry with a concentration of 2,000 ppm was prepared by dispersing spherical silica particles with an average particle size of 0.3 μm in ethylene glycol. Ethylene glycol to dimethyl terephthalate in 1:2 equivalents ratio mixing, and then adding a transesterification catalyst to the mixture for transesterification. Next, the prepared silica particle slurry was added, and a general polycondensation catalyst was added to complete the polycondensation reaction to prepare a polyester mixed resin with an intrinsic viscosity of 0.66 dl/gr.

2) Preparation of the first layer of resin

A silica particle slurry was prepared by dispersing spherical PS particles having an average particle size of 0.5 μm and spherical PS particles having an average particle size of 0.8 μm in ethylene glycol at a concentration of 2,000 ppm, respectively. Thereafter, the polyester hybrid resin for forming the first layer was prepared in the same manner as the resin for the second layer.

The polyester mixed resin prepared above is made according to the manufacturing method of co-extruded polyester film, and the first layer of resin and the second layer of resin are respectively dried, melted and extruded, and then joined by a feeding block die, at room temperature at room temperature. Cast on grinding drums to form into sheet form.

A polyester film structure having a thickness of 30 μm was prepared by stretching the formed sheet at a longitudinal stretch ratio of 3.4 times and a transverse stretch ratio of 3.5 times while heating.

Example 9 and Example 10

A polyester film structure was prepared in the same manner as in Example 8, except that the particle composition (particle type, particle size, content, etc.) was changed as described in Tables 4 and 5.

Comparative Example 1

A polyester base film was prepared in the same manner as in Example 1, except that silica particles (two particle sizes of 0.3 μm and 0.5 μm, respectively) were used as particles contained in the resin layer.

Comparative Example 2

A polyester base film was prepared in the same manner as in Example 1, except that the particle composition (particle diameter, content, etc.) of the polystyrene particles was changed as described in Table 3.

Comparative Example 3 to Comparative Example 7

A polyester film structure was prepared in the same manner as in Example 8, except that the particle composition (particle type, particle size, content, etc.) was changed as described in Tables 4 and 5.

Experimental Example 1 - Example 1 to Example 7 and Comparative Example 1 and Comparative Example 2

(1) Measurement of surface roughness (Ra, Rp)

The surface roughness of the first surface and the second surface of the polyester base film was measured using a three-dimensional surface roughness meter. Specifically, the surface roughness was measured by the JIS-B0601 measurement method using SE-3500 from KOSAKA.

(2) Friction coefficient measurement

The coefficient of friction between the first surface and the second surface was measured using a TOYOSEIKIA281300803 instrument after sampling the polyester base film to 11 cm in the width direction and 20 cm in the length direction according to the ASTM D 1894 standard. The load is 200g, the measurement speed is 50mm/min, each sample is measured 3 times, and the average value is taken.

(3) Measurement of indentation modulus

The indentation modulus of the second surface was measured according to the ISO 14577 standard using a diamond nano-indenter (berkovich tip, angle: 65.3°) from the company Probes.

(4) Number of pinholes in green sheet/deformation of green sheet

On the first surface of the polyester base films prepared according to the examples and comparative examples, 5 wt % of curable silicone resin (manufactured by Dow Corning, SYL-OFF 7920), 2 wt % of a curing agent (made by Dow Corning Co., Ltd., SYLOFF7923) and 93% by weight of distilled water, and dried at 200° C. for 20 seconds to form a release layer.

After that, the ceramic slurry was coated on the release layer by a slot die coater, the number of pinholes generated during the formation of a length of 100 m by molding the ceramic slurry on a 200 mm wide film was observed, and given Score between 1 (no pinholes) to 5 (multiple pinholes).

In addition, after molding the ceramic slurry, the dried green sheet was peeled off to a size of width x length (100 mm x 100 mm), and when the surface state was observed with an optical microscope magnified 40 times, the generation of unevenness was observed to evaluate the deformation of the green sheet. , specifically, a score between 1 point (no unevenness) to 5 points (a plurality of unevenness is observed) is assigned.

The evaluation results according to Experimental Example 1 are shown together in Table 1, Table 2, and Table 3 below.

Referring to Tables 1 to 3, when the indentation modulus is adjusted to be less than 4GPa (preferably 3GPa or more and less than 4GPa) in the case of an embodiment, a stable green sheet molding process is ensured while suppressing or reducing the surface deformation of the green sheet sex.

Experimental Example 2 - Example 8 to Example 10 and Comparative Example 3 to Comparative Example 7

(1) Surface roughness (Ra, Rz) measurement

The surface roughness of the first and second surfaces of the polyester film structure was measured using an optical interferometer non-contact 3D roughness meter (Zygo NewView 9000 3D Optical Profiler). Specifically, the mean value was obtained by measuring at 5 different locations, and the mean value calculated after repeating the measurement three times at each location (15 measurements in total) was used.

(2) Membrane wrinkle measurement

Under an LED light source, the polyester film structures of the Examples and Comparative Examples were visually observed at an angle of 45 degrees to measure the number of wrinkles having a width of 1 cm or more. The occurrence of wrinkles was evaluated based on the following criteria.

○: No wrinkles are observed

△: Two or less wrinkles are observed

X: 3 or more wrinkles are observed

(3) Evaluation of adhesion properties

After the film structures of Examples and Comparative Examples were placed in a rolled state for 1 week at room temperature, the film structures were released again to evaluate whether or not adhesion occurred (○: no adhesion occurred, X: adhesion phenomenon occurred)

(4) Evaluation of green sheet deformation

After coating a silicone release film on the second surface of the film structures of Examples and Comparative Examples, a ceramic slurry mixed with barium titanate and polyvinyl butene was applied to a thickness of about 2 μm and heated at 80 degrees dry. Then, the release film was removed, and it was observed whether or not a local indentation was generated on the surface of the ceramic layer bonded to the second surface.

Specifically, by measuring the 3D roughness for an area of 50 mm*100 mm, a region having a variation of 100 nm or more (ie, a portion including a deformation of 100 nm or more) is defined as a deformed portion. The evaluation criteria are as follows.

○: No deformed part is observed

△: Two or less deformed parts are observed

X: Three or more deformed parts were observed

The evaluation results are shown in Table 4 and Table 5 below together.

Referring to Tables 4 and 5, as described above, keep the surface roughness of the first and second surfaces In embodiments where the roughness ranges and the grain size characteristics in the first layer are controlled, deformation of the green sheet is suppressed while the process stability of the film structure itself is maintained.

In Comparative Example 3 and Comparative Example 4, the sum of roughness was excessively increased, resulting in deformation of the green sheet. Although the roughness of the comparative example 5 was adjusted to be low compared with the comparative example 3 and the comparative example 4, the particle size difference of the 1st layer became large, and the deformation|transformation of a green sheet was also caused. In the case of Comparative Example 6, the sum of the roughnesses decreased excessively, resulting in defects after the film structure was wound.

100: polyester film structure

100a: first surface

100b: Second surface

110: first floor

112: The first resin layer

114: The first particle

120: Second floor

122: Second resin layer

124: Second particle

Claims (20)

A polyester film structure comprising: a polyester resin layer having first and second surfaces facing each other; and particles dispersed in the polyester resin layer, Wherein, the second surface corresponds to the surface of the release coating, and the indentation modulus measured on the second surface using a nano-indenter is less than 4 GPa. The polyester film structure of claim 1, wherein the polyester resin layer comprises a first resin layer having the first surface and a second resin layer having the second surface, The particles include first particles dispersed in the first resin layer and second particles dispersed in the second resin layer, and The first particles and the second particles are organic particles. The polyester film structure according to claim 2, wherein the thickness of the second resin layer is 10 μm or more. The polyester film structure of claim 2, wherein the first particles have a larger particle size than the second particles. The polyester film structure of claim 2, wherein the content of the first particles in the first resin layer is greater than the content of the second particles in the second resin layer. The polyester film structure of claim 5, wherein the content of the first particles in the first resin layer is 0.4 to 1 wt %, and the content of the second particles in the second resin layer is 0.1 to 0.3 weight%. The polyester film structure according to claim 1, wherein the difference between the centerline average roughness (Ra) on the first surface and the second surface is 5 nm or more. The polyester film structure of claim 7, wherein the difference in centerline average roughness (Ra) on the first surface and the second surface is 5 to 20 nm. The polyester film structure according to claim 1, wherein the difference between the maximum peak height surface roughness (Rp) of the first surface and the second surface is 70 nm or more. The polyester film structure of claim 1, wherein the indentation modulus measured on the second surface using a nano-indenter is 2 GPa or more and less than 4 GPa. A polyester film structure comprising: a first layer comprising a first resin layer and first particles dispersed in the first resin layer; and a second layer laminated on the first layer and comprising a second resin layer and second particles dispersed in the second resin layer, The difference between D ₉₀ and D ₁₀ in the particle size distribution of the first particles is 500 nm or less, and the sum of the ten-point average roughness (Rz) of the first layer and the second layer is 200 nm or more. The polyester film structure of claim 11, wherein the difference between D ₉₀ and D ₁₀ of the first particles is in the range of 100 to 400 nm. The polyester film structure of claim 11, wherein the first particles comprise two or more kinds of particles with different particle sizes or materials. The polyester film structure of claim 13, wherein the difference in particle size (D ₅₀ ) between the two kinds of particles included in the first particle is 300 nm or less. The polyester film structure of claim 11, wherein the sum of the ten-point average roughness (Rz) of the first layer and the second layer is in the range of 200 to 500 nm. The polyester film structure of claim 11, wherein the surface of the first layer serves as a The process execution surface, and the surface of the second layer is used as the release coating surface. A polyester film structure comprising: a first layer comprising a first resin layer and first particles dispersed in the first resin layer; and a second layer laminated on the first layer and comprising a second resin layer and second particles dispersed in the second resin layer, wherein the sum of the ten-point average roughness (Rz) of the first layer and the second layer is in the range of 200 to 500 nm, and the sum of the centerline average roughness (Ra) of the first layer and the second layer and in the range of 10 to 30 nm. The polyester film structure of claim 17, wherein the Ra and Rz of the second layer are less than the Ra and Rz of the first layer, respectively, and The maximum peak height surface roughness (Rp) of the second layer is 100 nm or less. The polyester film structure of claim 17, wherein the particle size (D _{50 ) of the second particles is smaller than the particle size (D 50 )} of the first particles, and The first particles include two or more kinds of particles having different particle sizes or materials. The polyester film structure of claim 17, wherein the sum of the ten-point average roughness (Rz) of the first layer and the second layer is in the range of 200 to 400 nm, and the first layer and the second layer The sum of the centerline average roughness (Ra) of the two layers is in the range of 15 to 25 nm.

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