KR20190123080A - Release film for green sheet - Google Patents

Abstract

The present invention relates to a release film for molding a green sheet consisting of a release layer where a silicon composition is applied on a base film. As solvent resistance of the release layer is improved by adjusting the content of solids of the silicon composition and the coating amount of the release layer, excellent application, when coating ceramic slurry, is implemented. In addition, stains such as orange feel caused by the remaining of organic solvents of ceramic slurry in the release layer besides pin hole defect generated on the surface of the green sheet are improved, and the pin hole defect and the stains are improved so MLCC chip reliability is improved. For example, short defect after MLCC processing is reduced and dielectric breakdown voltage is improved.

Description

Release film for green sheet molding {RELEASE FILM FOR GREEN SHEET}

The present invention relates to a release film for forming a green sheet, and more particularly, a silicone composition is coated on a base film to form a release layer, thereby improving surface properties by controlling the coating amount of the release layer and the solid content of the silicone composition. In addition, the present invention relates to a release film for molding a green sheet suitable for MLCC (Multilayer Ceramic Chip Capacitor) requiring high reliability due to improved solvent resistance.

In general, the release film is a structure in which a release layer is formed on a polyester base film, and is used as an adhesive protective film, and is used as a carrier film for thinly and uniformly applying a ceramic slurry in a green sheet constituting an MLCC. Multilayer Ceramic Capacitor (MLCC) is a type of capacitor (battery battery) used for accumulating electricity or stabilizing current. Its small size and large capacitance make it widely used in portable electronic devices. The demand for this is increasing significantly. The MLCC is completed by stacking green sheets and internal metal electrodes in alternating tens or hundreds of layers, and then connecting external electrodes. The sizes vary from less than 1 mm to several nm, but gradually become smaller and thinner.

The green sheet used in the MLCC is formed by uniformly applying a ceramic slurry on a carrier film as a support and then baking. As a carrier film for forming the green sheet, a biaxially stretched polyester film having excellent mechanical strength, dimensional stability, heat resistance, and cost competitiveness is used as a base material, and a release film having a polymer silicone release layer coated on one surface thereof is used. . Recently, according to the trend toward miniaturization and high capacity of MLCC, it is required to make the green sheet thickness thinner and to laminate it in multiple layers. Specifically, the green sheet is manufactured to a thickness of 1 to 30 μm.

In the green sheet molding process, a release film having a flat surface that can uniformly apply the sheet and minimize the generation of pinholes is assumed. Pinholes are caused by wetting problems due to pores and film roughness factors caused by the protruding foreign matters in the slurry or air. Pinholes must be prevented absolutely because they directly lead to short circuits in the MLCC.

In addition, when the organic solvent used in the manufacture of the ceramic slurry is not sufficiently volatilized and remains in the release layer, stains such as orange peel occur on the surface of the green sheet. This problem is caused by the low solvent resistance of the release layer in addition to the roughness factor. It occurred when it remained in the release layer and needed improvement. Preventing the green sheet defects as described above is connected to the reliability improvement of the MLCC, so the function of the release film is very important.

Republic of Korea Patent No. 10-1522942

An object of the present invention is to improve the solvent resistance of the release layer in use in the ceramic green sheet molding process, and to improve the appearance of the ceramic slurry to achieve excellent coating properties by forming a green sheet molding release film suitable for MLCC that requires high reliability To provide.

Release film for molding green sheet of the present invention

Base film;

Consists of a release layer formed by coating a silicone composition on one surface of the base film,

Using the rubbing tester to the release layer satisfies the following formula 1 and formula 2.

1? (Equation 1)

0.01? Y? (Equation 2)

X: Peeling force after rubbing the release layer / peeling force before rubbing

 Y: difference between coating amount (g / m2) before rubbing and after rubbing

The total solid content of the silicone composition constituting the release layer is characterized in that 0.5 to 2.0% by weight.

The silicone composition is characterized in that it comprises an alkenylpolysiloxane, hydropolypolysiloxane, peel force control agent, silane coupling agent and platinum chelate catalyst.

The release layer after coating and drying the ceramic composition to a thickness of 1 to 5㎛ on the release layer is characterized in that 3 to 5gf / 25mm.

The surface fine hardness (DH) of the release layer is characterized in that from 0.2 to 10 gf / ㎛ ² .

In the present invention, by controlling the solids content of the silicone composition applied to the release layer and the coating amount of the release layer to improve the solvent resistance of the release layer, the organic solvent remaining in the ceramic slurry in the release layer other than the pinhole defect generated on the green sheet surface Improved stains such as orange peel. In addition, there is an effect of improving the reliability of the MLCC chip, such as short short after the MLCC processing, improved dielectric breakdown voltage.

1 is a schematic cross-sectional view of a release film for molding a green sheet of the present invention.

Hereinafter, a release film for molding a green sheet of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic cross-sectional view of a release film 10 for molding a green sheet of the present invention.

In the release film 10 for forming a green sheet of the present invention, the release layer 12 is laminated on the base film 11, and the release layer 12 includes a silicone composition.

1. Base Film

In the present invention, description will be focused on polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like, but the description of the present invention is not limited to polyester films or sheets. The polyester resin constituting the film is a polyester obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol, and the aromatic dicarboxylic acid isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid , Adipic acid, sebacic acid, oxycarboxylic acid, and the like, and as the aliphatic glycol, ethylene glycol, diethylene glycol, propylene glycol, butadiol, 1,4-cyclohexanedimethanol, neopentylglycol, etc. may be used. have. The said polyester resin can also use 2 or more types of said dicarboxylic acid component and glycol components together, and the copolymer containing a 3rd component is also possible. In addition, the polyester film according to the present invention uses a uniaxial or biaxially oriented film having high transparency and excellent productivity and processability. Representative polyester resins include polyethylene terephthalate (PET), polyethylene-2,6-natralene dicarboxylate (PEN), and the like.

In addition, the polyester film according to the present invention contains particles in order to give excellent roll-to-roll running characteristics, and the added particles are not particularly limited as long as they can exhibit excellent slipping characteristics. Specifically, particles of silica, silicon oxide, calcium carbonate, calcium sulfate, calcium phosphate, magnesium carbonate, barium carbonate, kaolin, aluminum oxide, titanium oxide, and the like may be included, and the shape of the particles used is not particularly limited. Preferably, any of spherical, block, rod and plate particles may be used. The particle size, specific gravity, and color of the particles are not particularly limited, but two or more kinds may be used in parallel if necessary, and the average particle diameter of the particles used is preferably 0.1 to 5 µm, more preferably 0.1. Use is in the range of 2 μm. At this time, when the average particle diameter of the particles is less than 0.1㎛ may cause aggregation between particles, poor dispersion may occur, while on the other hand, when the average particle diameter of the particles exceeds 5㎛ surface roughness characteristics of the film deteriorate post-processing Coating defects may occur.

In addition, when particle | grains are contained in a polyester base material layer, preferable particle content is 0.01 to 5 weight%, More preferably, it is 0.01 to 3 weight%. When the particle content is less than 0.01% by weight, the running characteristics of the polyester film may deteriorate, and when the content exceeds 5% by weight, the surface smoothness of the film may deteriorate.

2. Silicone release layer

The silicone release layer of the present invention is formed by application of a silicone release coating solution composed of an alkenylpolysiloxane, a hydropolypolysiloxane, a peel force control agent, a silane coupling agent and a platinum chelate catalyst.

In the silicone release coating liquid of the present invention, alkenyl polysiloxane may be any type such as addition type, condensation type, and ultraviolet curing type as a main component of the silicone release liquid, and is not particularly limited to any one. The alkenylpolysiloxane may have an alkenyl group bonded to a silicon atom per molecule in any part of the molecule, and preferably at least two are present. Further, the molecular structure is one selected from linear or branched phases, and a structure in which linear and branched phases coexist. More specifically, the alkenyl group bonded to the silicon atom is selected from the group consisting of vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group and heptenyl group. In addition, alkenyl groups that bond with silicon atoms in the alkenyl polysiloxane may be located along the molecular chain ends, the side chains of the spray chain, or the backbone of the molecular chain.

In the silicone composition of the present invention, the hydropolypolysiloxane is used as a curing agent, and may be any type such as addition type, condensation type, and ultraviolet curing type, and is not particularly limited to any one. The hydropolypolysiloxane may be linear, branched or cyclic, or a mixture thereof.

In addition, the viscosity and molecular weight are not limited, but compatibility with the alkenylpolysiloxane should be good, and the amount of the hydroelectron bonded to the silicon atom for one alkenyl group of the alkenylpolysiloxane is in the range of 1.0 to 2.0. desirable. If the alkenyl group of the alkenyl polysiloxane has less than 1.0 hydrogen atoms bonded to one silicon atom, good curing properties cannot be obtained. If the alkenyl group has more than 2.0 hydrogen atoms, there is a problem that the elasticity and physical properties after curing are lowered.

The silane coupling agent functions as a bridge between the substrate and the release layer. As a component of a silane coupling agent, any of epoxy silane type, amino silane type, vinyl silane type, methacryloxy silane type, and isocyanate silane type can be used, and one type or two or more types can also be used.

The silicone composition is coated in at least one surface of the polyester film after dilution in a solvent so that the total solid content of 0.5 to 2.0% by weight. The solvent used in the silicone composition can be used without limitation as long as it can disperse the solid content of the present invention and apply it onto a polyester film. If the total solids content of the silicone composition is less than 0.5% by weight, a uniform silicon coating layer may not be formed, and thus a problem of peeling after green sheet molding may occur. Thickness uniformity worsens and is not preferable.

After drying the release layer coating, the coating amount is formed to be 0.02 to 0.2 g / m 2. At this time, when the coating amount is less than 0.02 g / m 2, the coating property is poor during coating of the ceramic slurry, and pinhole defects are caused by coating unevenness. When the coating amount is more than 0.2 g / m 2, the solvent resistance to the solvent is deteriorated. The same stain can occur. Therefore, in order to express the film | membrane strength of a release layer and to express the outstanding solvent characteristic, the coating amount 0.02-0.2g / m <2> range is preferable.

Moreover, the surface fine hardness (DH) of a release layer is 0.2-10 gf / micrometer <^2> , More preferably, it is 0.2-8 gf / micrometer <^2> . When out of the range, there is a problem in that the leveling property defect and the adhesive force with the release layer is increased to cause the peeling defect during peeling.

The release layer of the present invention should exhibit excellent peeling properties in the uniform coating properties and lamination process of the ceramic slurry as described above. After coating and drying the ceramic composition on the release layer to a thickness of 1 to 5 μm, the peeling force is in the range of 3 to 5 gf / 25 mm when the green sheet is 0.3 mpm and 90 ° is peeled off using an AR-1000 peel force meter. At this time, if the peeling force is less than 3gf / 25mm, the adsorption degree between the green sheet and the substrate is poor, the lifting phenomenon appears and if the peeling force exceeds 5gf / 25mm, the green sheet is torn before peeling is performed in the green sheet lamination process Problems may arise.

Therefore, the release film for forming a green sheet according to the present invention may have 1≤≤ X <2 for the peeling force after rubbing the release layer / pre-rubbing (X) when rubbing 1 to 2 times using a rubbing tester on the release layer. Satisfies 0.01 ≤ ≤ Y ≤ ≤ 0.02 with respect to the difference (Y) between the amount of coating (g / m2) before rubbing and after rubbing, maintaining the release layer after rubbing and improving the solvent resistance of the release layer. It can be confirmed [ Table 1 ].

Hereinafter, the configuration of the present invention and its effects through the following examples will be described in more detail. This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Example 1>

Silicone, which has a solid content of 0.7% by weight after diluting 3 parts by weight of hydropolypolysiloxane, 15 parts by weight of peel force adjusting agent, 5 parts by weight of silane coupling agent, and 2 parts by weight of platinum chelate catalyst with respect to 100 parts by weight of alkenylpolysiloxane in toluene. The composition was prepared and applied to a polyester film (Toray Advanced Materials XD500 30 μm) in an amount of 0.02 g / m 2 to form a release layer. After the application, a heat treatment was performed for 30 seconds in a 150 ° C. hot air dryer to prepare a release film.

<Example 2>

The release film was manufactured in the same manner as in Example 1, except that the solid content of the silicone composition was 1.0 wt% and the coating amount of the release layer was 0.1 g / m 2.

<Example 3>

The release film was manufactured in the same manner as in Example 1, except that the solid content of the silicone composition was 1.5 wt% and the coating amount of the release layer was 0.2 g / m 2.

Comparative Example 1

The release film was manufactured in the same manner as in Example 1, except that the solid content of the silicone composition was 0.3 wt% and the coating amount of the release layer was 0.005 g / m 2.

Comparative Example 2

A release film was prepared in the same manner as in Example 1, except that the solid content of the silicone composition was 3.0 wt% and the coating amount of the release layer was 0.65 g / m 2.

Comparative Example 3

The release film was manufactured in the same manner as in Example 1, except that the solid content of the silicone composition was 3.5 wt% and the coating amount of the release layer was 0.8 g / m 2.

Experimental Example 1 Release layer peeling force and coating amount before and after rubbing

After rubbing the release layer of the release film with an organic solvent once or twice using a rubbing tester (300g of weight and the organic solvent-treated Sontara attached to the jig), the peeling force and coating amount before and after rubbing were measured. Indicated.

Peeling force: TESA7475 Tape laminated, AR-1000 0.3m / min speed, 180˚ peeling

Coating amount: XRF

As confirmed in Table 1, in the case of Example 1, the peeling force ratio before and after rubbing was 1.1, it was confirmed that the coating amount (g / ㎡) difference is constant to 0.01. In addition, Examples 1 to 3, the coating amount of the release layer was in the range of 0.02 to 0.2g / ㎡ to increase the crosslinking density of the silicone composition to maintain the release layer even after rubbing, it was confirmed that the solvent resistance improved when in the above range.

On the other hand, in Comparative Example 1, the coating amount was 0.005 g / m 2, and the release layer was not uniformly formed, so that the peeling stability was lowered, and the coating amount exceeded 0.2 g / m 2 as in Comparative Examples 2 and 3. Since the crosslinking density was not sufficient, the coating amount difference after the release layer rubbing was large, and the peeling force due to release of the release layer was increased.

<Experimental Example 2> Measurement of Surface Hardness of Release Layer

For the release layer of the release film, use a dynamic fine hardness tester (DUH-202 from SHIMADZU Co., Ltd.), hold the triangular cuff with a load of 2 gf on the surface of the release layer for 2 seconds, and then adjust the dynamic surface fine hardness (DH, gf / μm ² ). It calculated | required from following formula 3.

(식 3)

(Equation 3)

P (gf): test load

D (µm): Invasion Amount of Particles into Sample

α: 37.838 constant by particle shape (115 ° triangle crest)

As confirmed in Table 2, the films of Examples 1 to 3 according to the present invention can be confirmed that the fine hardness of the release layer is increased.

Experimental Example 3 Ceramic sheet analysis

The ceramic slurry was applied to a release layer of the release film in a thickness of 1 to 5 μm, and the slurry coating property, green sheet peelability, and appearance of the ceramic sheet were evaluated.

<Ceramic Composition Preparation>

To 100 parts by weight of barium titanate, 5 parts by weight of binder resin (polyvinyl butyral resin) was diluted to 10 parts by weight of toluene and MEK 1: 1 mixed solvent.

<Slurry coatability judgment criteria>

○: Good coatability

△: there is some shock phenomenon

X: slurry

<Green sheet peelability criterion>

○: gently peeled off

△: slightly heavy peeling

×: torn at the time of peeling or peeling too lightly

<Ceramic Sheet Appearance Criteria>

Optical Microscope Observes Surface of Ceramic Sheet Coated on Release Layer

○: no pinhole, orange peel

△: Pinhole, orange peel partially observed

×: Many pinholes and orange peels

<Green Sheet Peel Force Analysis Results>

Sample size 25mm x 150mm, AR-1000 0.3m / min, peeled at 90 ° angle

-Peeling force unit is gf / 25mm and the average of three measurements

As shown in Table 3, the release film prepared in Examples 1 to 3 shows stable results in slurry coatability and green sheet peelability, and the green sheet peeling force is in the range of 3 to 5 gf / 25 mm.

On the other hand, in Comparative Example 1, the pinhole defect was confirmed on the surface of the green sheet due to the release layer coating non-uniformity, and the peeling defect occurred when the green sheet was torn off. In addition, in Comparative Examples 2 and 3, the leveling property was poor at the time of coating, and thus the thickness uniformity was not good, and stains in the form of orange peel were observed on the green sheet surface.

From these results, the solvent content is improved by increasing the crosslinking density of the silicone composition in the range of 0.5 to 2.0 wt% of the solid content of the silicone composition and the coating amount of 0.02 to 0.2 g / m &lt; 2 &gt; Decreases.

10: Release film for green sheet molding
11: base film
12: release layer

Claims (5)

Base film;
Consists of a release layer formed by coating a silicone composition on one surface of the base film,
Release film for forming a green sheet satisfying the following formula 1 and formula 2 when rubbing using the rubbing tester on the release layer:
1? (Equation 1)
0.01? Y? (Equation 2)
X: Peeling force after rubbing the release layer / peeling force before rubbing
Y: difference of the coating amount (g / m <2>) before rubbing and after rubbing. The release film for forming a green sheet according to claim 1, wherein the total solid content of the silicone composition constituting the release layer is 0.5 to 2.0 wt%. The release film of claim 1, wherein the silicone composition comprises an alkenylpolysiloxane, a hydropolypolysiloxane, a peeling force regulator, a silane coupling agent, and a platinum chelate catalyst. The release film for forming a green sheet according to claim 1, wherein the release layer has a peel force of 3 to 5 gf / 25 mm after coating and drying the ceramic composition on the release layer in a thickness of 1 to 5 μm. The release film for forming a green sheet according to claim 1, wherein the surface fine hardness (DH) of the release layer is 0.2 to 10 gf / μm ² .

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