KR100879003B1 - Release Film - Google Patents

Abstract

The present invention relates to a release film suitable for manufacturing a green sheet used in a ceramic multilayer capacitor, which is a release film obtained by coating a release layer containing a curable silicone resin on at least one surface of a polyester base film and finally drying the coating layer. The change rate of dynamic friction coefficient defined by the following equation (K) using the dynamic friction coefficient measured after the process (according to ASTM D 1894) and the dynamic friction coefficient measured after one day after the drying process (according to ASTM D 1894) Value) is 10 to 80%, and it is useful as a release film for forming a ceramic green sheet which has excellent smoothness and no blocking and slip in the process, thereby minimizing thin film or thickness variation.

Change rate of dynamic friction coefficient (K value,%) = (X-Y) / X × 100

In the above formula, X is the dynamic friction coefficient measured after 10 minutes at 23 ℃, 50% RH after the final drying process when the release layer coating, Y is 1 day at 23 ℃, 50% RH after the drying process when coating the release layer The dynamic friction coefficient measured after

Description

Release Film {Release Film}

The present invention relates to a polyester release film having a release layer comprising a curable silicone resin, and more particularly, to a release film suitable for producing a green sheet used in a ceramic multilayer capacitor.

The release film containing a polyester film as a base material has been used as a carrier film for manufacturing the green sheet (henceforth a ceramic green sheet) for ceramic laminated capacitors.

In accordance with the recent miniaturization of electronic devices, electronic components such as capacitors and inductors have also been miniaturized, and ceramic green sheets themselves have also been thinned.

Therefore, in order to achieve high quality miniaturization while expressing the same capacity even though it is miniaturized, the most urgent task is to thin the ceramic green sheet and to secure thickness uniformity. Therefore, there is a demand for a release film having a high level of smoothness that can minimize the thickness variation of the green sheet, but there is insufficient provision of a release film that meets this purpose.

As part of this, Korean Patent Publication No. 2003-0055118 discloses that the pinhole formation of the ceramic slurry layer is greatly suppressed when the ceramic slurry is applied on the release film, and the thickness change rate of the ceramic layer when providing the ceramic layer on the release film. In order to provide a polyester film which can be given excellent release performance and is useful as a substrate for a release film, the maximum protrusion height Rmax is 500 nm or less on one side (surface A) of the polyester film, and Disclosed is a polyester film for a release film having a thickness change rate of 5% or less defined by the following formula using the maximum, minimum and average values of the film thickness in the longitudinal and transverse directions.

Thickness Change (%) = (Maximum Thickness-Minimum Thickness) × 100 / Average Thickness

Moreover, it also discloses the release film which contains a release layer in one side of such a polyester film.

In addition, Korean Patent Laid-Open Publication No. 1999-0088139 discloses a release film which can cope with thin film green sheet molding without blocking or the like even when a release film having a flat release layer surface is rolled onto a roll. The center line average roughness Ra of the surface of the release layer is 30 nm or less, and a distribution curve showing the relationship between the protrusion height (X) and the number of protrusions (Y) on the surface of the release layer has a protrusion height of 0.05 to 0.3 μm in the following formula (1). ), And the number of protrusions having a protrusion height of 0.4 µm or more on the surface of the release layer is 35 pieces / mm 2 or less.

logY≥-5X (where X is the protrusion height on the surface of the release layer in μm and Y is the number of protrusions on the surface of the release layer in pieces / mm 2) ------------- -(One)

In the case of these inventions, the surface roughness and thickness uniformity of the release layer coating surface of the polyester film used as the base material of the release film as the main factor for securing the surface smoothness of the release film, or the number of coarse particles.

However, the present inventors measured the dynamic friction coefficient value of the release film measured after 10 minutes after the final drying process after coating the release layer on one side of the polyester film and after 1 day after the final drying process. As a result, it was found that the change of the friction coefficient was quite severe, and based on this, the difference in the composition and thickness of the coating layer when the release layer was coated was confirmed, but the aging period of at least 24 hours was required. In addition, the present inventors focus on the necessity of the aging period, and when the release film is finally rewinded when the release layer is coated, the unreleased release layer has a compressive force that allows the winding form to be kept constant on the opposite side of the coating layer. It was confirmed that the most important factors affecting the surface smoothness of the release layer of the final release film were the change of the coefficient of kinetic friction with time after the final drying process and the surface roughness of the opposite side to which the release layer was applied in the base film.

As a result, the conventional technique, that is, the surface roughness control of the coating surface on which the release layer is coated, the thickness uniformity of the base film, the number of coarse particles control method such as providing a release film excellent in the release layer surface smoothness is limited. Have

Accordingly, an object of the present invention is to provide a polyester release film for forming a thin film having a high smoothness or a ceramic green sheet having a minimum thickness variation.

The release film of the present invention for achieving the above object is obtained by coating a release layer containing a curable silicone resin as a main component on at least one surface of the polyester base film, the dynamic friction coefficient measured after the final drying process (ASTM) By using the dynamic friction coefficient (according to ASTM D 1894) measured 1 day after the drying process) and satisfying the dynamic friction coefficient change rate (K value) defined by the following equation (1), 10 to 80% It is characterized by that.

Equation 1

Change rate of dynamic friction coefficient (K value,%) = (X-Y) / X × 100

In the above formula, X is the dynamic friction coefficient measured after 10 minutes at 23 ℃, 50% RH after the final drying process when the release layer coating, Y is 1 day at 23 ℃, 50% RH after the drying process when coating the release layer The dynamic friction coefficient measured after

The present invention will be described in more detail as follows.

In the present invention, 'polyester' refers to a polymer having an ester group prepared by polycondensation of dicarboxylic acid with diol or hydroxycarboxylic acid. Examples of the dicarboxylic acid that can be used in the present invention include terephthalic acid, succinic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanoic diacid, 2,6-naphthalenedicarboxylic acid and 1,4-cyclohexanedica. Lenic acid is mentioned. Examples of diols include ethylene glycol, 1,3-propanediol, 1,6-hexanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, neopentyl glycol, 1,4-cyclohexane dimethanol and polyethylene Can be mentioned. Examples of hydroxycarboxylic acids include p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.

Typical examples of such polyesters include polyethylene terephthalate, polybutylene terephthalate and polyethylene-2,6-naphthalate. These polymers may be those having homopolymers or copolymerized third components.

As the film of the present invention, a biaxially stretched film is preferably used in view of high strength and excellent dimensional stability, but an unstretched or at least one polyester film stretched in at least one direction can be used.

However, in order to satisfy the dynamic friction coefficient change rate, that is, K value of 10 to 80%, it is preferable that the surface roughness value of the opposite surface to which the release agent is to be applied in the polyester base film satisfies 10 to 45 nm.

At this time, the surface roughness value of the base film can be measured using a two-dimensional surface roughness meter.

The polyester base film satisfying such a surface roughness value may be a single layer or a multilayer film without departing from the technical spirit of the present invention.

Usually, it is preferable that the thickness of a polyester base film is 12-75 micrometers in consideration of the applied use.

The release film of the present invention is prepared by coating a composition containing a curable silicone resin on the surface to which the release agent on the polyester base film is to be applied to form a release layer.

Here, the curable silicone resin may be a resin of any curing reaction type, such as solvent addition type, solvent condensation type, solvent ultraviolet ray-curing type, solventless addition type, solventless condensation type, solventless ultraviolet curing type, solventless electron beam curing type and the like. .

In addition to such a curable silicone resin, the curing agent is included in the release agent composition, and the content of the curing agent is preferably 1.0 to 2.5% by weight in the total release agent composition. The content of the curing agent ultimately affects the rate of change of the dynamic friction coefficient (K value), and if the content is small, it causes a problem that silicon transfer due to uncuring occurs.

On the other hand, the release agent composition includes a solvent included in the usual release layer composition, the solvent includes both aqueous or organic. Moreover, particle | grains may be added as needed in order to improve the blocking prevention, slipperiness, etc. of the surface of a release layer. As the kind of particles to be used, any of organic particles and inorganic particles may be used, and is not particularly limited thereto.

As a method of apply | coating the mold release agent of such a composition to the said polyester base film, a well-known coating system, such as a reverse roll applicator, a gravure applicator, a bar applicator, can be used.

The coating amount of the release layer also affects the adjustment of the K value. If the coating amount of the release layer is too large, the K value becomes too large, and if the coating amount of the release layer is too small, the K value becomes smaller than 10%. . In order to satisfy K value at 10 to 80%, it is preferable to adjust the release layer coating amount to about 0.1 to 0.3 g / m 2.

After coating the release layer, it is usually dried for 5 to 30 seconds at 120 to 230 ℃.

As described above, the K value may be adjusted by appropriately adjusting factors such as the surface roughness value of the opposite surface to which the release layer is to be applied in the base film, the amount of the release agent applied, and the content of the curing agent in the release agent composition. %, Preferably it is 25-50%.

If the K value is less than 10%, pinholes occur in the release layer due to incomplete curvature, and the peeling force tends to increase rapidly during ceramic coating, or the final rewinding form is uneven during the release layer coating process due to slip. Has the disadvantage of being. In addition, when the K value is greater than 80%, the silicon release layer may have a problem such as transferring or blocking phenomenon to the opposite surface of the release layer coating surface.

According to the present invention, unlike the prior art, the surface roughness of the base film to which the release layer is to be applied, the amount of release agent applied, and the amount of the curing agent in the release agent composition are controlled, and as a result, the rate of change of the dynamic friction coefficient with time after the release layer coating is controlled. By doing so, it is possible to produce a release film having excellent smoothness and no blocking and slip in process.

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.

The measuring method of the present invention is as follows.

(1) Surface roughness (Ra) measurement

Measurement Method: JIS B 0651

Equipment used: 2D surface roughness meter (kosaka, model AK-11)

(2) Measurement of dynamic friction coefficient and rate of change of dynamic friction coefficient

Measurement Method: ASTM D 1894

Device: Friction tester (Toyoseki, Model TR type)

Measurement condition: Friction coefficient measurement between the release layer coated surface and the opposite surface of the polyester release film

The coefficient of change of dynamic friction coefficient was measured (X) after 10 minutes at 23 ° C. and 50% RH after the final drying process after coating the release layer, and at 1 ° C. and 50% RH after the drying process. The dynamic friction coefficient after one day was measured (Y), and it measured by the following formula.

Dynamic friction coefficient change rate (K value,%) = (X-Y) / X × 100

(3) silicone transcription evaluation

A value: Before coating the release layer, the Nitto 31B tape was laminated with a 2 kg rubber roll on the base film on the opposite side to which the release layer was to be coated, and then peeled after storage for 1 day at 23 ° C. and 50% RH at a pressure of 20 gf / cm 2. Force (T-peel test, crosshead speed 300 mm / min)

B value: 1 day after the release layer coating, the Nitto 31B tape was laminated with a 2 kg rubber roll on the base film coated with the release layer, and then subjected to a pressure of 20 gf / cm 2 at 23 ° C. and 50% RH for 1 day. Peel force measured after storage (T-peel test, crosshead speed 300 mm / min)

Poor: B value is less than 80% of A value

Good: When B value is more than 80% of A value

(4) coating properties evaluation

Measurement Method: Visual Inspection

Good: No scratches or pinholes on release coating surface

Poor: scratches and pinholes on the release coating surface

(5) Blockability evaluation

After cutting the sample to a size of 10cm × 10cm, 10 sheets of release film is laminated so that the opposite side and the opposite surface contact, and then pressed at 100 ℃, 1 hour, 50gf / ㎠ conditions to determine the blocking.

Good: No blocking occurs.

Poor: Blocking occurs.

Example 1

Curable silicone resin (DOW Corning, SYL-OFF 7920) on a polyester base film having a surface roughness (Ra) value of 23 nm on the surface to which the release agent is to be applied and a surface roughness (Ra) on the opposite surface of 20 nm and a thickness of 38 μm. A release agent consisting of 5% by weight, a curing agent (manufactured by Dow Corning, SYL-OFF 7923) and 93% by weight of distilled water was applied to a coating amount of 0.14 g / m 2, dried at 230 ° C. for 10 seconds to form a release layer. A film was obtained.

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

Example 2

A release film was prepared in the same manner as in Example 1 except that a film having a surface roughness (Ra) of 20 nm and a surface roughness (Ra) of the opposite side of the polyester-based film on which the release agent was applied was 23 nm. It was.

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

Example 3

Prepare a release film in the same manner as in Example 1 except that the surface roughness (Ra) value of the surface to which the release agent is applied as a polyester base film is 30nm, the surface roughness (Ra) of the opposite side is 27nm and the thickness is 75 A film of μm was used.

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

Example 4

Prepare a release film in the same manner as in Example 3 except using a film having a surface roughness (Ra) of the surface to which the release agent is applied as a polyester base film is 27 and the surface roughness (Ra) of the opposite side is 30 nm It was.

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

Example 5

Prepare a release film in the same manner as in Example 3 except using a film having a surface roughness (Ra) of 35 and a surface roughness (Ra) of 40 nm on the opposite side as a polyester base film It was.

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

Comparative Example 1

Curable silicone resin (DOW Corning, SYL-OFF 7920) on a polyester base film having a surface roughness (Ra) value of 35 on the surface to which the release agent is to be applied and a surface roughness (Ra) on the opposite surface of 40 nm and a thickness of 75 μm. A release agent consisting of 5% by weight, a curing agent (0.5% by weight of Dow Corning, SYL-OFF 7923) and 94.5% by weight of distilled water was applied to a coating amount of 0.05g / m 2 and dried at 230 ° C. for 10 seconds to form a release layer. A film was obtained.

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

Comparative Example 2

Curable silicone resin (DOW Corning, SYL-OFF 7920) on a polyester substrate film having a surface roughness (Ra) value of 30 on the surface to which the release agent is to be applied and a surface roughness (Ra) on the opposite surface of 27 nm and a thickness of 75 μm. A release agent consisting of 5% by weight, a curing agent (manufactured by Dow Corning, SYL-OFF 7923) and 93% by weight of distilled water was applied to a coating amount of 0.05g / m 2 and dried at 230 ° C. for 10 seconds to form a release layer. A film was obtained.

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

Comparative Example 3

Curable silicone resin (DOW Corning, SYL-OFF 7920) on a polyester substrate film having a surface roughness (Ra) value of 30 on the surface to which the release agent is to be applied and a surface roughness (Ra) on the opposite surface of 27 nm and a thickness of 75 μm. A release agent consisting of 5% by weight, a curing agent (0.5% by weight of Dow Corning, SYL-OFF 7923) and 94.5% by weight of distilled water was applied to a coating amount of 0.40 g / m 2 and dried at 230 ° C. for 10 seconds to form a release layer. A film was obtained.

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

Comparative Example 4

Curable silicone resin (DOW Corning, SYL-OFF 7920) on a polyester substrate film having a surface roughness (Ra) value of 30 on the surface to which the release agent is to be applied and a surface roughness (Ra) on the opposite surface of 27 nm and a thickness of 75 μm. A release agent consisting of 5% by weight, a curing agent (DOW Corning, SYL-OFF 7923) 0.5% by weight and 94.5% by weight of distilled water was applied to a coating amount of 0.14 g / m 2, dried at 230 ° C. for 10 seconds to form a release layer. A film was obtained.

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

Example Comparative example One 2 3 4 5 One  2 3 4 Surface roughness of base film (Ra, nm) Side to which release layer will be applied 23 20 30 27 35 35 30 30 30 Opposite side to which release layer will be applied 20 23 27 30 40 40 27 27 27 Base film thickness (㎛) 38 38 75 75 75 75 75 75 75 Curing agent content (% by weight) in the release agent composition 2 2 2 2 2 0.5 2 0.5 0.5 Release layer coating amount (g / ㎡) 0.14 0.14 0.14 0.14 0.14 0.05 0.05 0.40 0.14 Release layer surface roughness (Ra, nm) 19 23 25 29 38 39 25 26 24 Dynamic friction coefficient change rate (K value,%) 27 32 44 57 78 98 9 92 87 Coating evaluation Good Good Good Good Good Good Bad Good Good Silicon transcription evaluation Good Good Good Good Good Bad Good Bad Bad Blocking evaluation Good Good Good Good Good Good Good Bad Good

From the results of Table 1, in the case of Examples 1 to 5, the coefficient of change of the dynamic friction coefficient was 27 to 78%, which is excellent in coating property, that is, smoothness and transfer of the release layer to the opposite side of the release layer coating surface from the silicon transfer evaluation result. It can be seen that there is no, blocking does not occur in the process. On the other hand, when the coefficient of change of dynamic friction coefficient is less than 10% as in Comparative Example 2, slippage may occur due to poor coating properties, and when the coefficient of change of dynamic friction coefficient is greater than 80% as in Comparative Examples 1, 3, and 4, It can be seen that transcription or blocking occurs.

Examples 6-10

To prepare a release film in the same manner as in Examples 1 to 5, respectively, except that the release agent composition was 7 wt% of a curable silicone resin (manufactured by Shin-Etsu Co., KS 3755), and 2 wt% of a curing agent (Shin-Etsu Co., CAT-PL 50T). %, The solvent was used to dry the methyl ethyl ketone / toluene mixed solvent 91% by weight for 30 seconds at 120 ℃.

The properties of the obtained release film are shown in Table 2 below.

Comparative Example 5

Curable silicone resin (Shin-Etsu Co., KS 3755) to a polyester base film having a surface roughness (Ra) value of 35 on the surface to which the release agent is to be applied and a surface roughness (Ra) on the opposite surface of 40 nm and a thickness of 75 μm. A release agent consisting of a weight%, a curing agent (0.5% by weight of CAT-PL 50T manufactured by Shin-Etsu Co., Ltd.), and 92.5% by weight of a methyl ethyl ketone / toluene mixed solvent as a solvent was applied to a coating amount of 0.05 g / m 2 and then applied at 120 ° C. for 30 seconds. It dried and formed the release layer, and obtained the release film.

The properties of the obtained release film are shown in Table 2 below.

Comparative Example 6

On the polyester base film whose surface roughness (Ra) value of the surface to which a mold release agent is apply | coated is 30, and the surface roughness (Ra) of the opposite surface is 27 nm and thickness is 75 micrometers, curable silicone resin (Shin-Etsu company make, KS 3755) 7 A release agent composed of a weight%, a curing agent (Shin-Etsu Co., Ltd., CAT-PL 50T) 2% by weight, 91% by weight of methyl ethyl ketone / toluene mixed solvent as a solvent was applied to a coating amount of 0.05g / ㎡ for 30 seconds at 120 ℃ It dried and formed the release layer, and obtained the release film.

The properties of the obtained release film are shown in Table 2 below.

Comparative Example 7

On the polyester base film whose surface roughness (Ra) value of the surface to which a mold release agent is apply | coated is 30, and the surface roughness (Ra) of the opposite surface is 27 nm and thickness is 75 micrometers, curable silicone resin (Shin-Etsu company make, KS 3755) 7 A release agent composed of a weight%, a curing agent (0.5% by weight of CAT-PL 50T manufactured by Shin-Etsu Co., Ltd.), and 92.5% by weight of methyl ethyl ketone / toluene mixed solvent as a solvent was applied so that the coating amount was 0.40 g / m 2, and the resultant was heated at 120 ° C. for 30 seconds. It dried and formed the release layer, and obtained the release film.

The properties of the obtained release film are shown in Table 2 below.

Comparative Example 8

On the polyester base film whose surface roughness (Ra) value of the surface to which a mold release agent is apply | coated is 30, and the surface roughness (Ra) of the opposite surface is 27 nm and thickness is 75 micrometers, curable silicone resin (Shin-Etsu company make, KS 3755) 7 A release agent consisting of a weight%, a curing agent (0.5% by weight of CAT-PL 50T, manufactured by Shin-Etsu Co., Ltd.), and 92.5% by weight of a methyl ethyl ketone / toluene mixed solvent as a solvent was applied to a coating amount of 0.14 g / m 2, and then applied at 120 ° C. for 30 seconds. It dried and formed the release layer, and obtained the release film.

The properties of the obtained release film are shown in Table 2 below.

Example Comparative example 6 7 8 9 10 5  6 7 8 Surface roughness of base film (Ra, nm) Side to which release layer will be applied 23 20 30 27 35 35 30 30 30 Opposite side to which release layer will be applied 20 23 27 30 40 40 27 27 27 Film thickness (㎛) 38 38 75 75 75 75 75 75 75 Curing agent content (% by weight) in the release agent composition 2 2 2 2 2 0.5 2 0.5 0.5 Release layer coating amount (g / ㎡) 0.14 0.14 0.14 0.14 0.14 0.05 0.05 0.40 0.14 Release layer surface roughness (Ra, nm) 25 22 27 28 36 37 26 25 25 Dynamic friction coefficient change rate (K value,%) 25 28 41 54 73 93 7 97 83 Coating evaluation Good Good Good Good Good Good Bad Good Good Silicon transcription evaluation Good Good Good Good Good Bad Good Bad Bad Blocking evaluation Good Good Good Good Good Good Good Bad Good

From the results of Table 2, in the case of Examples 6 to 10, the coefficient of change of the coefficient of kinetic friction is 25 to 73%, which is excellent in coatability, that is, smoothness and transfer of the release layer to the opposite side of the release layer coating surface from the silicon transfer evaluation It can be seen that there is no, and it can be seen that no blocking occurs in the process. On the other hand, when the coefficient of change of dynamic friction coefficient is less than 10%, as in Comparative Example 6, slippage may occur due to poor coating properties, and when the coefficient of change of dynamic coefficient of friction is greater than 80% as in Comparative Examples 5, 7, and 8, It can be seen that transcription or blocking occurs.

As described above in detail, according to the present invention, the release film formed such that the change in the dynamic friction coefficient measured after the final drying process and the dynamic friction coefficient measured after 1 day after the drying process satisfies a certain value is obtained according to the present invention. It is useful as a release film for molding a ceramic green sheet which has excellent smoothness and does not generate blocking and slip in the process and minimizes a thin film or thickness variation.

Claims (5)

In a release film obtained by coating a release layer containing a curable silicone resin on at least one surface of a polyester base film, The dynamic friction coefficient measured after the final drying process (based on ASTM D 1894) and the coefficient of dynamic friction measured after 1 day after the drying process (based on ASTM D 1894) when the release layer was coated were defined by Equation 1 below. The dynamic friction coefficient change rate (K value) satisfies 10 to 80%, The release layer is a release film, characterized in that formed in 0.1 to 0.3g / ㎡ coating amount. Equation 1 Change rate of dynamic friction coefficient (K value,%) = (X-Y) / X × 100 In the above formula, X is the dynamic friction coefficient measured after 10 minutes at 23 ℃, 50% RH after the final drying process when the release layer coating, Y is 1 day at 23 ℃, 50% RH after the drying process when coating the release layer The dynamic friction coefficient measured after The release film according to claim 1, wherein the surface roughness of the opposite surface on which the release layer is to be formed in the polyester base film satisfies 10 to 45 nm. delete The release film according to claim 1 or 2, wherein the release layer comprising the silicone curable resin comprises a curing agent in an amount of 1.0 to 2.5% by weight in the total composition. delete