WO2020242276A1 - Release film - Google Patents

Abstract

The present invention relates to a release film, which is free from blocking and curling, has a low surface roughness so as to be suitable for an MLCC manufacturing process, and does not curl even at a high coating thickness so as to prevent, when applied to the MLCC manufacturing process, floating of a ceramic sheet and defective stacking, and thus can contribute to a reduction in production costs and defective rate.

Description

Release film

The present invention relates to a release film, and more particularly, it is free from blocking and curling, is suitable for the MLCC manufacturing process due to its low surface roughness, and does not cause curls despite the high coating thickness, so when applied to the MLCC manufacturing process, ceramic sheet It relates to a release film that can contribute to reducing the production cost and defect rate of MLCC by preventing the lifting and lamination defects.

In general, a release film is a protective film for protecting an adhesive component from foreign substances or unwanted adherends in the atmosphere by attaching a pressure-sensitive adhesive film, and a release layer containing a polymer silicone as a main component is provided on one side of the base film.

Another special use of the release film is for the manufacturing process of laminated ceramic capacitors (hereinafter referred to as MLCC). MLCC is manufactured by laminating several hundred layers of a thin ceramic sheet and a metal electrode. In this case, a release film is used as a carrier film for manufacturing a thin ceramic sheet. That is, after coating the ceramic slurry on the release film, the dried ceramic slurry is peeled off from the release film, thereby obtaining a thin ceramic sheet. In the case of a release film applied to such an MLCC process, the surface roughness indicating the surface roughness of the release film is the most important characteristic because projections or irregularities on the release film cause pin hole defects in the ceramic sheet. For this reason, the industry continues to make efforts to lower the surface roughness.

In general release films in the art, the surface roughness of the polyester film used as the substrate is 20 to 50 nm, but the coating thickness of the release layer is as thin as 100 nm, so the surface roughness of the release film is usually determined by the surface roughness of the substrate. Therefore, in order to lower the surface roughness of the release film, it is common to prepare a polyester film having a lower surface roughness and use it as a substrate. However, in the polyester film manufacturing process, special particles are required to lower the surface roughness, and the yield and productivity of the film are also poor, so applying such a film as a substrate inevitably causes an increase in the production cost of the release film.

Therefore, in order to lower the surface roughness of the release film, it is easy for those skilled in the art to consider a method of coating the coating thickness of the release layer sufficiently thick compared to the surface roughness of the base material. When the coating thickness exceeds (about 200 nm) of the polymer silicone, a so-called blocking phenomenon in which the release layer has adhesiveness occurs due to the low viscoelasticity of the polymer silicone, and the winding process (the process of winding the film in a roll form) becomes impossible.

As a method for obtaining a release film having a lower surface roughness without causing such a blocking phenomenon, a method of coating a separate smoothing layer on the substrate and coating the release layer again on the smoothing layer has been proposed (Korea Patent Publication No. 10-2016-0127036). In such a multilayer coating, when the smoothing layer has a sufficiently dense structure, the viscosity of the coating layer is low, so there is an advantage that the surface roughness can be lowered without causing blocking. However, since this method requires a separate coating process, there are disadvantages in that the process cost increases and the yield decreases.

In addition, as a method for achieving the above objective by a single layer coating process, a method of forming a release layer by mixing a melamine resin having a dense structure that does not cause blocking and a polyorganosiloxane resin that is easy to control releasability has been proposed. Yes (Republic of Korea Patent Publication No. 10-2018-0020945). However, such a release film has a so-called curl phenomenon in which the release film bends toward the coating layer due to heat shrinkage of the melamine resin. Particularly, there is a problem that the curl phenomenon is remarkable when heated at high temperature and for a long time, and when curl occurs in the release film, the release film In the process of forming and laminating the ceramic sheet, there is a problem that lamination defects or lift-off of the ceramic sheet occur.

The present invention has been devised to solve the above problems and meet the requirements of the prior art, and an object of the present invention is to provide a release layer having an effect of lowering the surface roughness of the base material and release property, thereby providing a lower surface roughness than the conventional It is intended to provide a release film.

Another object of the present invention is to provide a release film capable of preventing lamination and lifting of ceramic sheets when applied to MLCC because curl does not occur at room temperature and high temperature.

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

The above object includes a base material, a release layer formed on one side of the base material, and the release layer is achieved by a release film formed of a release coating composition comprising melamine resin, polydimethylsiloxane and polyether copolymer resin, and polyethylene glycol.

Here, the release layer is characterized in that the weight ratio of melamine resin, polydimethylsiloxane and polyether copolymer resin, and polyethylene glycol is 1.0: 0.01 to 0.10: 0.1 to 1.0.

Preferably, the release coating composition further comprises an acid catalyst and an organic solvent, and further comprises 0.1 to 10 parts by weight of an acid catalyst based on 100 parts by weight of the melamine resin.

Preferably, the substrate has a ten point average roughness (SRz) of 500 nm or less.

Preferably, the thickness after drying of the release layer is 0.5 to 3.0 times the ten point average roughness (SRz) of the substrate.

Preferably, the melamine resin is characterized in that it comprises a melamine resin having two or more alkoxy or alkoxyalkyl groups.

Preferably, the melamine resin is characterized by having at least two or more functional groups of a methoxy group, a methoxymethyl group and a butoxymethyl group.

Preferably, the polyether is characterized in that it contains at least one of polyethylene glycol or polypropylene glycol.

Preferably, the polydimethylsiloxane and polyether copolymer resin is characterized in that hydroxy groups are bonded to both ends.

Preferably, the release film is characterized in that the residual adhesion rate is 90% or more.

Preferably, the release film is characterized in that the room temperature curl (Curl) generation amount is 0 to 1mm.

Preferably, the release film is characterized in that the high-temperature curl generation amount is 0 to 1 mm.

Preferably, the release film satisfies the following Equation 1,

(Equation 1)

0.25 <(F_SRz/B_SRz) <0.90

Where F_SRz is the ten point average roughness of the surface of the release layer, and B_SRz is the ten point average roughness of one surface of the substrate that does not contact the release layer.

According to the present invention, a release film having a lower surface roughness of the release layer compared to the substrate can be obtained by only one coating process, and there is an effect such as being free from blocking and curling compared to the prior art.

Furthermore, the present invention has an effect of having a release layer having a high coating thickness, which is suitable for the MLCC manufacturing process, and can be used for manufacturing a ceramic sheet having a lower thickness, since the surface roughness is low compared to the prior art.

Furthermore, the present invention has a special resin mixing ratio, so that curl does not occur despite a high coating thickness, so when applied to the MLCC manufacturing process, the ceramic sheet can be prevented from lifting and lamination failure, thereby contributing to the reduction of the production cost and defect rate of MLCC. Has the effect of.

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

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

Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention and drawings. These examples are only illustratively presented to illustrate the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by these examples. .

Unless otherwise defined, 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 may be used in the practice or testing of the present invention, suitable methods and materials are described herein.

As used herein, "comprise", "comprising", "include", "including", "containing", "~ The terms characterized by", "has", "having" or any other variation thereof are intended to cover inclusions that are not exclusive. For example, a process, method, article, or apparatus comprising a list of elements is not necessarily limited to those elements, and is not explicitly listed or may include other elements inherent to such process, method, article, or apparatus. May be. Further, unless expressly stated to the contrary, "or" refers to an inclusive'or' and not an exclusive'or'.

In describing and/or claiming the present invention, the term “copolymer” is used to refer to a polymer formed by copolymerization of two or more monomers. Such copolymers include binary copolymers, terpolymers or higher order copolymers.

First, a release film according to an aspect of the present invention will be described in detail with reference to FIG. 1, which is a schematic cross-sectional view of a release film according to a preferred embodiment of the present invention.

Referring to FIG. 1, a release film according to an embodiment of the present invention includes a base material and a release layer 20 formed on one side of the base material, and is released by heat drying and curing after coating a release coating composition on one side of the base material. Layers can be formed.

In one embodiment, the substrate 10 may be a polyester film as long as it is a commercial polyester film, and a biaxially stretched polyethylene terephthalate film having a thickness of 20 to 100 μm may be used.

As for the surface roughness of the polyester film as a substrate, it is preferable that SRz, which is a ten point average roughness measured by a contact type three-dimensional roughness meter, is 500 nm or less. When the SRz exceeds 500 nm, even if the release layer proposed in the present invention is provided, the surface roughness of the release film is high, and when used in the MLCC process, pinhole defects in the ceramic sheet may be caused. In addition, in order to lower the surface roughness, a release layer having a higher coating thickness is required, so there is a problem in that economic efficiency is inferior.

In one embodiment, the release coating composition constituting the release layer 20 may include a melamine resin, a copolymer resin of polydimethylsiloxane and polyether, and polyethylene glycol.

Among the release coating compositions, melamine resin is the main component of the release layer, and by giving the release layer a high modulus of elasticity, it suppresses the blocking phenomenon of the release film and makes the winding process smooth.

It is preferable that the melamine resin includes a melamine resin having two or more alkoxy or alkoxyalkyl groups. If the number of alkoxy or alkoxyalkyl groups in the melamine resin is one or not, the resin is not cured and the release layer cannot be formed. More preferably, it is preferable to include at least two of a methoxy group, a methoxymethyl group and a butoxymethyl group. In the case of melamine having an alkoxyalkyl group having a longer chain than a butoxymethyl group, since a high amount of heat is required for curing the melamine resin, there is a problem that the substrate undergoes thermal deformation such as wrinkles during the curing process.

Among the release coating compositions, the polydimethylsiloxane and polyether copolymer resin makes the release film have excellent releasability, and has a function of having excellent durability by tightly bonding with the melamine resin, which is the main component.

It is preferable that the polydimethylsiloxane and polyether copolymer resin have hydroxyl groups at both ends for bonding with the melamine resin. It is preferable that the polyether unit in the copolymer skeleton contains at least one of polyethylene glycol and polypropylene glycol. If the chain length of the polyether resin constituting the copolymer is longer than that of polypropylene glycol, the compatibility with the melamine resin is lowered, and a high amount of heat is required for curing.Therefore, the substrate undergoes thermal deformation such as wrinkles during curing. have.

Among the release coating compositions, polyethylene glycol is the greatest technical feature of the present invention. By adding it, the heat shrinkage of the release layer is significantly reduced, and a release film that does not cause curls even after a long heat treatment at high temperature can be prepared.

Although there is no particular restriction on the polyethylene glycol, it is preferable to use a polyethylene glycol having a hydroxy group having a molecular weight of 400 or less, which is relatively low in viscosity, quick reaction, and economical.

In one embodiment, the content ratio (weight ratio) of a melamine resin, a copolymer resin of polydimethylsiloxane and polyether, and polyethylene glycol is preferably 1.0: 0.01 to 0.10: 0.1 to 1.0.

If the content of the polydimethylsiloxane and polyether copolymer resin is less than the above preferable range, there is a problem that the release of the release film is insufficient and the ceramic sheet is not peeled smoothly. If it exceeds the above preferable range, the release layer is formed while using the release film. There is a problem that some of the resins are transferred to the ceramic sheet.

In addition, when the content of polyethylene glycol is less than the above preferable range, there is a problem that curling occurs at room temperature and high temperature due to insufficient function to alleviate the heat shrinkage of the release layer.If the content exceeds the above preferable range, the hardening degree of the release layer is insufficient or elasticity is poor. As a result, blocking occurs during the release film winding process.

In one embodiment, the release coating composition constituting the release layer may include an acid catalyst in addition to the above components.

There is no specific restriction on the acid catalyst, and a commercial product such as paratoluenesulfonic acid that has good compatibility with melamine resin and can accelerate curing can be used. The acid catalyst is preferably contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the melamine resin. If the content of the acid catalyst is less than 0.1 parts by weight, it requires a high amount of heat to cure the release layer, so it may cause thermal deformation of the curing process substrate. If it exceeds 10 parts by weight, the pot life of the release coating composition is short and it is cured before coating. There is a problem that happens.

In one embodiment, the release coating composition constituting the release layer may include an organic solvent in addition to the above components.

Any organic solvent that is compatible with melamine resin can be used. Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, methanol, ethanol, butanol, isopropyl alcohol, isobutyl alcohol, One or two or more of ethyl acetate, butyl acetate, propyl acetate, isopropyl acetate, hexane, heptane, octane, and isooctane may be used in combination.

In one embodiment, the release coating composition is configured by appropriately adjusting the total solid content and viscosity to be suitable for the coating process, and when using a gravure coating, it is preferable to have a solid content of 1 to 10% and a viscosity of 50 cps or less.

In addition, there is no particular limitation on the method of coating the release coating composition, and bar coating, gravure coating, die coating, comma coating, etc. may be used.

After coating the release coating composition, it is preferable to apply a hot air dryer for drying and curing, and a cured release film can be obtained by heating at a temperature of 140° C. for 30 seconds.

In addition, the thickness of the release layer after drying and curing is completed is preferably 0.5 to 3.0 times the ten point average roughness (SRz) of the substrate. The release layer of such a thickness has a flat surface layer covering the protrusion of the substrate, so that the surface roughness of the release layer is lower than that of the conventional release film. The thickness of the release layer after drying is the coating thickness measured by observing the cross section with a scanning electron microscope after preparing the release film.

If the thickness of the release layer is less than the above preferable range, the effect of reducing the surface roughness through the release coating is insignificant, causing pinhole defects in the ceramic sheet when used.If the thickness of the release layer exceeds the above preferable range, blocking in the release film winding process Will occur.

In addition, it is preferable that the relationship between the ten point average roughness (F_SRz) of the surface of the release layer and the ten point average roughness (B_SRz) of the surface opposite to the release coating layer of the base material satisfies the following equation.

(Equation 1)

0.25 <(F_SRz/B_SRz) <0.90

In one embodiment, it is preferable that the residual adhesion rate of the release film is 90% or more, and if the residual adhesion rate of the release film is less than 90%, short circuit failure of the MLCC occurs as some components of the release coating layer are transferred to the ceramic sheet during the use of the release film. Can cause.

In one embodiment, it is preferable that the release film has a room temperature curl of 0 to 1 mm, and a high temperature curl of 0 to 1 mm. When the amount of curling in the release film exceeds the above range, there is a problem that lamination of the ceramic sheet is defective or lifted in the process of forming and laminating the ceramic sheet on the release film.

Therefore, according to the present invention, since the release layer has the function of alleviating the surface roughness of the substrate, it is possible to provide a release film having a lower surface roughness compared to the prior art. Also, the heat shrinkage of the release layer is small, so that curls are prevented even when heated at high temperatures A release film that does not occur can be provided.

In particular, the release film according to the present invention may be suitable for use as a carrier film for forming a ceramic sheet during the manufacturing process of a multilayer ceramic capacitor (MLCC), and may contribute to improving process defects such as pinholes and meandering, and have a lower thickness. As ceramic sheet production becomes possible, it can greatly contribute to improving the physical properties of MLCC.

Hereinafter, the present invention will be described in more detail through examples and comparative examples. These examples are for explaining the present invention in more detail, and the scope of the present invention is not limited by these examples.

[Examples 1 to 9 and Comparative Examples 1 to 7]

1. Base film

A polyethylene terephthalate film (manufacturer: Toray Advanced Materials, product name: EXCEL) having a core point average roughness (SRz) of 130 nm, 400 nm, and 900 nm, respectively, was used as the base film, and as shown in Table 1, each Example and Comparative Example were divided into Applied. And the surface roughness of both sides of the base film is the same.

2. Release coating composition

(a) Melamine resin having a methoxy group and a methoxymethyl functional group as a melamine resin (manufacturer: Cytec, product name: Cymel-325)

(b) Polydimethylsiloxane and polyether copolymer resin, which has hydroxyl groups at both ends and repeating units of polyethylene glycol and polypropylene glycol (manufacturer: DOW, product name: OFX-3667)

(c) Polyethylene glycol resin having a molecular weight of 400 having hydroxyl groups at both ends (manufacturer: Sigma Aldrich, product name: PEG-400)

(d) an acid catalyst composed of 40% by weight of paratoluenesulfonic acid and the balance of organic solvent (manufacturer: Allnex, product name: Cycat-4040)

(e) An organic solvent in which methyl ethyl ketone and cyclohexanone are mixed 1:1

A release coating composition was prepared by mixing the components (a) to (e) at a weight ratio, respectively, as in the Examples and Comparative Examples of Table 1 below.

3. Release coating and curing

Examples 1 to 9 and Comparative Example 1 by coating the release coating composition prepared above with a Mayer bar (manufactured by Cheminstruments, #5 mesh) on one side of the base film and then curing by heating at 150°C for 30 seconds using a hot air dryer. After drying of ~7, a release film having a release layer thickness was prepared, respectively.

division	Base film	Release coating composition (g)					Release layer thickness (nm)
	SRz(nm)	a	b	c	d	e
Example 1	130	6.0	0.1	3.0	0.6	100	279
Example 2	130	6.0	0.3	3.0	0.6	100	282
Example 3	130	6.0	0.5	3.0	0.6	100	282
Example 4	130	6.0	0.3	1.0	0.6	100	278
Example 5	130	6.0	0.3	5.0	0.6	100	281
Example 6	130	1.8	0.09	0.9	0.18	100	80
Example 7	130	3.0	0.15	1.5	0.3	100	142
Example 8	130	7.8	0.39	3.9	0.78	100	358
Example 9	400	7.8	0.39	3.9	0.78	100	358
Comparative Example 1	130	6.0	0.05	3.0	0.6	100	271
Comparative Example 2	130	6.0	0.7	3.0	0.6	100	275
Comparative Example 3	130	6.0	0.3	0.5	0.6	100	271
Comparative Example 4	130	6.0	0.3	7.0	0.6	100	280
Comparative Example 5	130	1.2	0.06	0.6	0.12	100	55
Comparative Example 6	130	9.0	0.45	4.5	0.9	100	481
Comparative Example 7	900	12.0	0.6	6.0	1.2	100	555
a: melamine resin, b: polydimethylsiloxane and polyether copolymer resin, c: polyethylene glycol, d: acid catalyst composed of 40% by weight of paratoluenesulfonic acid and remaining amount of organic solvent, e: organic solvent (methylethylketone and cyclo Hexanone 1:1 mixture)

Physical properties were measured through the following experimental examples using the release films according to Examples 1 to 9 and Comparative Examples 1 to 7, and the results are shown in Table 2 below.

[ Experimental example ]

1. Surface roughness measurement

SRz, which is a ten point average roughness, was measured from the release films prepared in Examples and Comparative Examples using a contact type three-dimensional surface roughness meter (KOSAKA SE3300, cutoff 0.25). The surface of the release layer (F_SRz) and the opposite surface of the release layer (B_SRz) were measured and compared.

2. Blocking evaluation

Each release film prepared in Examples and Comparative Examples was stacked on each base film so that the release layer was in contact with the base film surface, and the presence or absence of blocking was evaluated after leaving for 24 hours under a load of 100 gf/cm 2. The superimposed release film was visually observed under a fluorescent lamp, and it was judged as'good' when no marks due to blocking were observed, and'defective' when blocking marks were observed.

3. Evaluation of pinhole defect of ceramic sheet and measurement of peel force

After mixing 100 g of barium titanate particles having an average particle diameter of 0.2 μm, 10 g of polyvinyl butyral, 8 g of toluene, and 2 g of butanol, stirring at room temperature for 12 hours and then ball milling at 500 rpm for 24 hours to prepare a ceramic slurry. This was coated on the release layer of the release film according to Examples and Comparative Examples to a predetermined thickness using an applicator and then hot air dried at 80° C. for 5 minutes to prepare a release film having an average thickness of 1 μm. Thereafter, an area of 1 mm ² was observed 10 times with an interferometric microscope, and if the number of pinholes exceeding 1 μm on average was more than 1 per unit area (mm ² ), it was judged as'poor' and other than that, it was judged as'good'.

In addition, an adhesive tape (manufacturer: Nitto, product name: 31B) was attached to the surface of the ceramic sheet and the peeling force was measured when peeling it at a 180° angle and a 10 mpm speed. An AR-1000 device manufactured by cheminstrument was used to measure the peel force.

4. Curl (room temperature) measurement

The release films according to Examples and Comparative Examples were cut into a square having a side length of 10 cm, and then the release layer was placed on a flat glass plate with the release layer on top, and curls were measured. The height of the part raised the highest from the glass plate was measured with a ruler and marked.

5. Curl (high temperature) measurement

The release films according to Examples and Comparative Examples were heated at 150° C. for 30 minutes using a hot air dryer, and then curl was measured in the same manner as for room temperature curl.

6. Measurement of residual adhesion rate

(1) Sample peel force measurement

A standard adhesive tape (TESA7475) was rubbed and attached to the release films according to Examples and Comparative Examples by reciprocating once with a 2 kg roller. After peeling the attached tape, the peeling force was measured when peeling again after attaching to the base film not subjected to release coating.

At this time, the peeling force was measured at 0.3mpm, 180° angle, and the peeling force at the time of peeling was measured, and the measuring instrument was an AR-1000 product of Cheminstrument.

(2) Measurement of standard peel force

A standard adhesive tape (TESA7475) was rubbed and adhered to the base film not subjected to release coating by reciprocating once with a 2 kg roller. The peeling force when peeling this was measured.

(3) Measurement of residual adhesion rate

The residual adhesion rate was calculated by the formula of [Sample peel force]/[Standard peel force]*100%.

	F_SRz(nm)	B_SRz(nm)	F_SRz/B_SRz	blocking	Curl(mm)		Residual adhesion rate (%)	Ceramic sheet
					Room temperature	High temperature		Pinhole	Peel force (gf/in)
Example 1	63	131	0.48	Good	0	0	96	Good	4.4
Example 2	63	142	0.44	Good	0	0.2	94	Good	3.5
Example 3	67	126	0.53	Good	0	0	93	Good	3.1
Example 4	71	119	0.60	Good	0	0.2	95	Good	3.3
Example 5	59	131	0.45	Good	0	0	95	Good	3.6
Example 6	109	124	0.88	Good	0	0	93	Good	4.9
Example 7	91	126	0.72	Good	0	0	93	Good	4.4
Example 8	33	127	0.26	Good	0	0.2	93	Good	2.2
Example 9	109	411	0.27	Good	0	0.4	93	Good	1.9
Comparative Example 1	65	127	0.51	Good	0	0.2	97	Good	14.1
Comparative Example 2	67	119	0.56	Good	0	0.2	84	Good	2.9
Comparative Example 3	63	126	0.50	Good	2.2	7	94	Good	3.4
Comparative Example 4	59	137	0.43	Good	0	0.2	83	Good	4.2
Comparative Example 5	139	141	0.99	Good	0	0.2	97	Bad	6.1
Comparative Example 6	21	119	0.18	Bad	0	0.4	93	Good	2.8
Comparative Example 7	651	931	0.70	Good	0.2	0.6	92	Bad	2.4

As can be seen from Table 2, the release films according to Examples 1 to 9 prepared from the release coating composition having a preferred configuration provided by the present invention showed good properties in various evaluation results. Due to the relatively high thickness of the release coating, the ten point average roughness (F_SRz) of the surface of the release layer was lowered compared to the ten point average roughness (B_SRz) of the surface of the substrate, and as a result, pinhole defects did not occur even when manufacturing the ceramic sheet. can confirm. In addition, despite the relatively high thickness of the release layer, it can be seen that the amount of curling at room temperature and high temperature has a preferable range of 1 mm or less.

In addition, in the constitution of the release coating composition, the content of (b) polydimethylsiloxane and polyether copolymer resin affects the residual adhesion rate and the peeling force of the ceramic sheet. In the MLCC industry, it is preferable that the residual adhesion rate of the release film is usually 90% or more, and if it is less than 90%, it is known that short failure may occur after MLCC production. In addition, it is preferable that the peeling force when peeling the ceramic sheet is usually 5gf/in.If this is exceeded, the ceramic sheet is not partially peeled off during the peeling of the ceramic sheet during the MLCC manufacturing process, and tearing or wrinkles are mixed. I can. It can be seen that the release films according to Examples 1 to 9 prepared from the release coating composition having a preferred configuration provided by the present invention show values in a preferable range in both the residual adhesion rate and the ceramic sheet peeling force.

On the other hand, in the case of Comparative Example 1 in which the content of the polydimethylsiloxane and the polyether copolymer resin was less than the preferred range provided by the present invention, the peeling force of the ceramic sheet was formed very high as 14.1 gf/in, and Comparative Example 2 exceeding the preferred range. In the case of, the residual adhesion rate was 84%, which was less than the preferred range.

In addition, in the composition of the release coating composition, (c) polyethylene glycol has a function of lowering room temperature and high temperature curl, but unlike Examples 1 to 9 having a preferable content provided in the present invention, Comparative Example 3 lacks the content of polyethylene glycol. As a result, it can be confirmed that curls at room temperature and high temperature are severely generated. In addition, in the case of Comparative Example 4, the content of the polyethylene glycol (a) is higher than the content of the melamine resin, so that the release layer is not sufficiently cured, and thus the residual adhesion rate is less than the preferred range.

In addition, in the case of Examples 1 to 9 in which the correlation between the base film's ten point average surface roughness (B_SRz) and the release coating layer thickness is within the preferred range provided by the present invention, the ten point average roughness (F_SRz) of the release coating layer surface is 110 nm. It can be seen that the pinhole defect of the ceramic sheet does not occur as it is formed extremely low below.

On the other hand, in the release film of Comparative Example 5 exceeding the range of Equation 1, the thickness of the release coating layer was thinner than that of B_SRz, and as the F_SRz of the release layer showed a high value of 139 nm, it could be confirmed that pinhole defects in the ceramic sheet were caused . In addition, it can be seen that the release film of Comparative Example 6, which is less than the range of Equation 1, has a thicker release coating layer than B_SRz, and thus blocking occurs in the release film winding process.

In addition, in the case of the release film of Comparative Example 7, the relationship between B_SRz and the release coating layer thickness is within the preferred range suggested by the present invention, but as the B_SRz of the substrate itself exceeds 500nm, which is the preferred range of the present invention, a high of 651nm even after release coating. It can be seen that F_SRz is shown to cause a pinhole defect in the ceramic sheet.

As described above, in the case of manufacturing a release film from a release coating composition having a special configuration provided by the present invention, a release film having a lower surface roughness of the release layer compared to the substrate can be obtained with only one coating process. Differently, it is possible to obtain a release film free from blocking and curling.

In particular, the release film according to the present invention is suitable for the MLCC manufacturing process, and may contribute to manufacturing a ceramic sheet having a lower thickness without pinhole or lamination defects. In addition, in MLCC, since the thickness of the ceramic sheet is directly related to the capacity and size of the product, the release film according to the present invention can contribute not only to improving the defect rate in the process but also improving the physical properties of the finished product, the MLCC.

In the present specification, only a few examples of various embodiments performed by the present inventors are described, but the technical idea of the present invention is not limited or limited thereto, and it is obvious that it may be modified and variously implemented by those skilled in the art.

Claims (13)

1. materials;

   Includes; a release layer formed on one side of the substrate,

   The release layer is formed of a release coating composition comprising a melamine resin, polydimethylsiloxane and polyether copolymer resin, and polyethylene glycol, a release film.
2. The method of claim 1,

   The release layer has a weight ratio of melamine resin, polydimethylsiloxane and polyether copolymer resin, and polyethylene glycol is 1.0: 0.01 to 0.10: 0.1 to 1.0, a release film.
3. The method of claim 1,

   The release coating composition further comprises an acid catalyst and an organic solvent,

   A release film further comprising 0.1 to 10 parts by weight of an acid catalyst based on 100 parts by weight of the melamine resin.
4. The method of claim 1,

   Ten point average roughness (SRz) of the substrate is 500 nm or less, a release film.
5. The method of claim 1,

   The thickness after drying of the release layer is 0.5 to 3.0 times the ten point average roughness (SRz) of the substrate, a release film.
6. The method of claim 1,

   The melamine resin includes a melamine resin having two or more alkoxy or alkoxyalkyl groups, a release film.
7. The method of claim 1,

   The melamine resin has a functional group of at least two or more of a methoxy group, a methoxymethyl group and a butoxymethyl group, a release film.
8. The method of claim 1,

   The polyether is a release film containing at least one of polyethylene glycol or polypropylene glycol.
9. The method of claim 1,

   The polydimethylsiloxane and polyether copolymer resin is a release film in which hydroxyl groups are bonded to both ends.
10. The method of claim 1,

    The release film has a residual adhesion rate of 90% or more.
11. The method of claim 1,

    The release film is a room temperature curl (Curl) generation amount of 0 to 1mm, a release film.
12. The method of claim 1,

    The release film is a high temperature curl (curl) generation amount of 0 to 1mm, a release film.
13. The method according to any one of claims 1 to 12,

    The release film satisfies the following Equation 1,

    (Equation 1)

    0.25 <(F_SRz/B_SRz) <0.90

    Where F_SRz is the ten point average roughness of the surface of the release layer, and B_SRz is the ten point average roughness of one surface of the base material not in contact with the release layer.

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