JP2002192661A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film which is suitably used as a carrier film for molding, especially a ceramic green sheet, with regard to the release film. SOLUTION: This release film is constituted of an antistatic layer, which is composed mainly of a binder resin and an antistatic agent, formed on at least one of the sides of a polyester film and a mold release layer composed mainly of a curable silicone resin formed on the antistatic layer. The release film is characterized in that the dynamic hardness(DH) of the mold release layer is within the range indicated by the formula 1 DH>=8.0 (gf/μm2) and the relationship among the solid content weight (W: g/m2) of the binder resin, the solid content weight (WB: g/m2) of the antistatic agent and the solid content weight (WC: g/m2) of the curable silicone resin per unit area of the mold release layer, satisfies the following formulae 2 and 3: 0.25<=WB/WA<=1.2 formula 2 and 0.25<=(WA+WB)/WC<=1.2 formula 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release film, and more particularly to a release film suitably used as a carrier film for forming a ceramic green sheet.

[0002]

2. Description of the Related Art Polyester films made of polyethylene terephthalate, polyethylene naphthalate, etc.
Although widely used as a carrier film for forming ceramic green sheets, it generally has a high electrical insulation property, causing peeling charge when peeling off the molded product from the polyester film. Problems such as exfoliation have occurred. In particular, those using an organic solvent at the time of molding desirably have little peeling charge. For example, when peeling electrification occurs, when the molded articles are stacked and stored after peeling, the molded articles may be displaced or collapse due to static electricity, thereby significantly reducing the work efficiency. In particular, ceramic green sheets formed on carrier films have recently become thinner with the miniaturization and larger capacity of ceramic capacitors. The charging was large, and the resulting electrostatic damage was a major problem.

As a method for preventing the release charging of the release film, there is a method of providing an antistatic layer on the surface opposite to the surface on which the release layer is formed. However, when the release film is stored in the form of a roll, a phenomenon occurs in which the antistatic layer migrates to the surface of the release layer (so-called backside transfer), and the releasability of the release layer is significantly reduced.

Further, an antistatic layer is provided on the release layer forming surface,
In the case where a cured silicone resin is used as a release layer on the surface of the antistatic layer, conventionally, poor curing of the silicone resin and a remarkable decrease in adhesion between the release layer and the antistatic layer have occurred. Furthermore, in order to obtain antistatic performance with a surfactant, it is indispensable that a surfactant is present on the surface of the release layer, but conventionally, it is impossible to make a surfactant exist on the surface of the release layer. Even if it can be done, the adhesion of the release layer, the problem of reduced releasability when used as a carrier film, problems such as back migration occurs, forming a release layer on the antistatic layer,
It was difficult.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a release film having a small release charge, excellent release properties of a release layer, and no back transfer of an antistatic layer. is there.

[0006]

According to the present invention, the polyester film has an antistatic layer mainly composed of a binder resin and an antistatic agent on at least one side of the polyester film, and mainly comprises a curable silicone resin on the antistatic layer. A release film having a release layer, wherein the dynamic hardness (DH) of the release layer is in the range represented by the following formula 1, and the solid content of the binder resin per unit area of the antistatic layer. Weight (WA: g / m ² ), solid weight of antistatic agent (WB: g / m ² ), solid weight of curable silicone resin per unit area of release layer (WC: g / m ² ) Satisfies the following formulas (2) and (3). DH ≧ 8.0 (gf / μm ² ) Equation 1 0.25 ≦ WB / WA ≦ 1.2 Equation 2 0.25 ≦ (WA + WB) /WC≦1.2 Equation 3

The release film of the present invention specifies the relationship between the solid content of the binder resin in the antistatic layer and the solid content of the antistatic agent and the solid content of the curable silicone resin in the release layer, as described below. As a range, by having a release layer on the antistatic layer, the back transfer of the antistatic layer to the release layer by storing the release film in a roll shape, or by contact of the roll in the ceramic green sheet forming step Contamination due to the adhesion of the antistatic layer to the roll is prevented,
In the entire release film, by having an antistatic layer, the charge decay is fast, the peeling charge during the molding of the ceramic green sheet using the release film of the present invention is reduced,
The peeled ceramic may re-adhere to the release film,
There is no heavy peeling due to static electricity, and problems in the ceramic green sheet forming step can be prevented.

Further, the dynamic hardness (DH) of the release layer
Is within the range represented by the above formula 1, whereby the release property of the release film from the ceramic green sheet in the release step at the time of forming the ceramic green sheet using the release film of the present invention is improved. The occurrence of tearing or peeling failure of the green sheet is prevented.

[0009] Further, per unit area of the antistatic layer,
Solid weight of binder resin (WA: g / m ² ), solid weight of antistatic agent (WB: g / m ² ), solid weight of curable silicone resin per unit area of release layer (W
When the relationship of C: g / m ² ) satisfies the above formulas 2 and 3, it is possible to provide a release layer on the antistatic layer and allow an antistatic agent such as a surfactant to be present on the surface of the release layer. It has excellent balance between the antistatic property and the adhesion to the polyester film which is the base material of the release layer, and is excellent in both the antistatic property and the peeling property at the time of forming the ceramic green sheet using the release film of the present invention. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The release film of the present invention uses a polyester film as a substrate. The configuration of the polyester resin forming the polyester film used in the present invention is not particularly limited, and polyethylene terephthalate or polyethylene naphthalate generally used for a base material of a release film can be used. These polyester resins are obtained, for example, by polycondensing an aromatic dicarboxylic acid such as terephthalic acid or 2,6-naphthalenedicarboxylic acid with an aliphatic glycol such as ethylene glycol or diethylene glycol. In the present invention, as the polyester resin, a crystalline linear saturated polyester composed of an aromatic dicarboxylic acid component and a diol component is preferable, and examples thereof include polyethylene terephthalate, polyethylene-2-6 naphthalate, and polymethylene terephthalate.

The polyester resin for forming the polyester film used in the present invention may contain other components as long as the action of the present invention is not impaired. Organic fine particles and inorganic fine particles for improving the lubricating property and the sliding property. In particular, it is preferable to contain fine particles having an average particle diameter of 0.01 to 10 μm at a ratio of 0.005 to 5% by weight.

The polyester film used in the present invention is preferably biaxially stretched from the viewpoint of mechanical strength and the like.

The polyester film used in the present invention may have a single-layer structure or a multilayer structure composed of two or more layers of the same or different polyester resins.

The thickness of the polyester film used in the present invention is not particularly limited, but is preferably from 2 to 300 μm, and more preferably from 10 to 125 μm. If the thickness of the polyester film is less than 2 μm, the polyester film may be thermally wrinkled during the formation of the release layer or during the application and drying of the ceramic slurry when the ceramic green sheet is formed using the release film of the present invention. It tends to occur, and the flatness of a ceramic green sheet formed using the release film of the present invention tends to decrease. If the thickness exceeds 300 μm, the rigidity of the polyester film becomes too high, and the handleability tends to decrease.

The method for producing the polyester film used in the present invention is not particularly limited, and a commonly used method can be used. For example, as a method for producing a polyester film, a polyester resin as a constituent material is extruded into a molten film by an extruder, and is cooled by a rotary cooling drum to obtain an unstretched film. A method of stretching in a uniaxial or biaxial direction is used. The uniaxially stretched film is obtained by uniaxially stretching the unstretched film in the machine direction or the transverse direction. Further, the biaxially stretched film is a method of successively biaxially stretching the above-described longitudinally or transversely uniaxially stretched film, and further laterally or vertically, or simultaneously stretching an unstretched film vertically and horizontally. It is obtained by a stretching method. The stretching conditions are not particularly limited, but the stretching temperature is preferably equal to or higher than the secondary transition point (Tg) of the polyester resin as a constituent material. When a biaxially stretched film is used, the stretching ratio is preferably 1 to 8 times, particularly 2 to 6 times in each of the longitudinal direction and the lateral direction.

The release film of the present invention has an antistatic layer mainly composed of a binder resin and an antistatic agent on at least one side of the polyester film.

In the present invention, the antistatic agent used in the antistatic layer is not particularly limited, and a surfactant or the like can be used. Examples of the surfactant include an anionic antistatic agent having a functional group of an alkyl sulfate type or an alkyl phosphate type, and a cationic charging agent having a quaternary ammonium salt type, a quaternary ammonium resin type, or an imidazoline type. And nonionic antistatic agents such as sorbitan type and ether type, and amphoteric antistatic agents such as betaine type. Also, a conductive antistatic agent such as polyaniline can be used. Preferably, a cationic antistatic agent is used.

In the present invention, the binder resin used for the antistatic layer is not particularly limited, and a synthetic resin can be used. Preferably, it is a polyvinyl resin.
Examples of the polyvinyl resin include polyvinyl alcohol (PVA) obtained by saponifying a vinyl acetate resin, and polyvinyl butyral.
And a resin obtained by acetalizing polyvinyl alcohol such as toluene (PVB). Particularly preferred is polyvinyl butyral (PVB). When the release film of the present invention is used for forming a ceramic green sheet, a certain degree of transparency is required to detect a defect of the ceramic green sheet. For example, polyvinyl butyral (PVB), which is transparent when formed into a thin film and has high adhesiveness to a polyester film and is easily mixed with an antistatic agent, is preferable.

In the present invention, the coating amount of the antistatic layer is not particularly limited, and can be set according to the use of the release film of the present invention.
5 g / m ² is good. If the coating amount of the antistatic layer is smaller than the above range, the antistatic performance tends to decrease. On the other hand, if it is larger than the above range, a large amount of the antistatic agent in the antistatic layer precipitates on the surface of the release layer, and it is difficult to obtain a desired release property.

In the present invention, the antistatic layer may contain, in addition to the antistatic agent and the binder resin, other components as long as the action of the present invention is not impaired.

In the present invention, the method of forming the antistatic layer is not particularly limited, and can be appropriately set according to the constituents thereof. The constituents of the antistatic layer may be dissolved in a solvent if necessary.
A method of dispersing, applying on a polyester film, and then drying and curing is used.

The release film of the present invention has a release layer mainly composed of a curable silicone resin on the antistatic layer. The type of the curable silicone resin is not particularly limited,
A known curable silicone resin capable of forming a layer having releasability can be used. In the present invention, it is preferable to use a light release type curable silicone resin. Curable silicone resins include, for example, addition reaction systems such as solvent addition type and solventless addition type, condensation reaction systems such as solvent condensation type and solventless condensation type, solvent ultraviolet curing type, and solventless ultraviolet curing. Any curing reaction type such as an ultraviolet curable type such as a mold and an electron beam curable type such as a solventless electron curable type can be used. These may be used alone or in combination of two or more.

As the curable silicone resin of the addition reaction type, for example, a resin cured by forming a three-dimensional crosslinked structure by reacting polydimethylsiloxane having a vinyl group introduced at a terminal with hydrogen silane using a platinum catalyst. Is mentioned.

As the curable silicone resin of the condensation reaction system, for example, a silanol group (Si—OH group) in a base silicone polymer and a functional group of a crosslinking agent in the presence of an organic tin catalyst (eg, an organic tin acylate catalyst) (For example, a polydimethylsiloxane having a terminal -OH group and a terminal-
Dehydrocondensation with polydimethylsiloxane (hydrogensilane) having an H group to form a siloxane bond (Si-O-Si) to crosslink and cure by forming a three-dimensional crosslinked structure. To do

As the curable silicone resin of the ultraviolet curable type and the electron beam curable type, for example, the most basic type uses the same radical reaction as ordinary silicone rubber crosslinking, and the acrylic functional group is used for the silicone rubber. And a photocuring method, a method in which a strong acid is generated by decomposition of an onium salt with ultraviolet rays to cleave an epoxy group to crosslink, and a method in which thiol is added to vinylsiloxane to crosslink. Since electron beams have higher energy than ultraviolet rays, in the case of an electron beam curing system, a radical crosslinking reaction occurs without using an initiator unlike the ultraviolet curing system.

Specific examples of commercially available cured silicone resins used in the present invention include KS-718, KS-708A, and KS-7 manufactured by Shin-Etsu Chemical Co., Ltd.
74, KS-830, KS-775, KS-778, K
S-779H, KS-847, KS-776, X-62
-2422, X-62-2461, KS-3600, K
S-856, DKQ manufactured by Dow Corning Asia Ltd.
3-202, DKQ3-203, DKQ3-204, D
KQ-205, DKQ3-210, SRX-357, SRX-211, manufactured by Toray Dow Corning Silicone Co., Ltd.
SPEX211, SP7243S, XS56-A1652 manufactured by Toshiba Silicone Co., Ltd., TPR-6700, T
PR-6701, TPR-6721, TPR-6720
And the like.

In the present invention, the curable silicone resin forming the release layer is preferably one that is obtained by crosslinking a siloxane compound with a metal catalyst.

In the present invention, the method for forming the release layer is not particularly limited, and the curable silicone resin can be cured to form a layer on the antistatic layer. The method of applying the curable silicone resin on the antistatic layer includes, for example, a method of diluting the curable silicone resin with a solvent, if necessary, to form a coating solution, and applying the solution. As a coating method, a method generally used conventionally, for example, a wire barcode method, a doctor blade method, a microgravure coating method, a gravure roll coating method, a reverse roll coating method, an air knife coating method, a rod coating method, a die coating method, Kiss coat method, reverse kiss coat method, impregnation method,
A curtain coating method, a spray coating method or the like can be used alone or in combination.

In the present invention, the coating amount of the curable silicone resin on the antistatic layer is 1 to 20 g / m when wet.
² , and more preferably 2 to 15 g /
m ² is good. The coating amount of the release layer is preferably from 0.01 to 0.3 g / m ² in a dry state, and more preferably from 0.03 to 0.15 g / m ² . When the coating amount of the release layer is less than 0.01 g / m ² , the squealing property at the time of forming the ceramic green sheet is reduced, and it is difficult to obtain satisfactory performance of the ceramic green sheet.
When the ceramic green sheet is peeled from the release film, the peeling is likely to be heavy or torn. Further, it is difficult to obtain a uniform release layer, and the peeling force tends to partially vary and lack stability. The coating amount of the release layer is 0.3 g / m ²
If the thickness is thicker, it takes time to dry after coating, which is inconvenient in production, the curing of the release layer is insufficient, the non-backside transferability is reduced, and problems other than the peeling performance such as blocking are likely to occur. Become.

In the present invention, the method and conditions for drying and curing the curable silicone resin layer in the release layer can be appropriately set according to the components constituting the release layer, and methods such as heat curing and radiation curing can be used. . In the case of thermosetting silicone, drying conditions are preferably 60 to 150 ° C. for about 30 seconds. When the drying condition is less than 60 ° C. or less than 30 seconds, the effect of the silicone resin is insufficient, and the adhesion between the silicone resin layer and the polyester film is reduced. In the case of an ultraviolet-curable curable silicone resin, it is preferable that the integrated irradiation amount be about 50 to 500 mJ / cm ² .

In the present invention, the release layer may contain other components as long as the action of the present invention is not impaired.

The release film of the present invention may have other layers in addition to the antistatic layer and the release layer as long as the function of the present invention is not impaired.

In the present invention, the release layer is required to be slightly peeled from a hard surface such as a ceramic green sheet. Therefore, the release layer needs to have a certain degree of hardness. Further, in the evaluation of the releasability on a hard surface such as a ceramic green sheet or the like, a clear peeling force value cannot be obtained by a commonly used pressure-sensitive adhesive peeling evaluation method. The peeling of the adhesive is related to the elasticity of the adhesive layer, and the peeling of the release film from a hard surface such as a ceramic green sheet is not based on the interfacial peeling force of the adhesive layer and the release film, but on the interface shear force. Because it is affected.

Therefore, as a criterion for evaluating the releasability, the release film of the present invention has a dynamic hardness (DH) of the release layer.
Must be in the range represented by the following formula 1, preferably in the range represented by the following formula 4, and more preferably in the range represented by the following formula 5.
And particularly preferably the range represented by the following formula 6. Dynamic hardness is 8.0 (gf /
If it is less than ² μm ² ), the influence of the strain due to the release layer cannot be ignored, and the release property of the release film from the ceramic green sheet in the release step at the time of forming the ceramic green sheet using the release film of the present invention. In particular, in the case of a thin ceramic green sheet, the ceramic green sheet often breaks or peels poorly at the time of peeling, causing problems such as a decrease in yield. DH ≧ 8.0 (gf / μm ² ) Formula 1 DH ≧ 10.0 (gf / μm ² ) Formula 4 DH ≧ 15.0 (gf / μm ² ) Formula 5 DH ≧ 20.0 (gf / μm ² ) Equation 6

In the present invention, since the release layer comes into contact with the ceramic slurry during the formation of the ceramic green sheet as described later, the adhesion of the release layer to the base material, that is, the release layer to the antistatic layer. Adhesion and adhesion of the antistatic layer to the substrate are required. The adhesiveness can be evaluated by a rub-off value. The release film of the present invention has a rub-off value of 10
It is preferably at most 5, more preferably at most 5. If the rub-off value is larger than 10, the ceramic green sheet is eroded by the organic solvent contained in the ceramic slurry as described below, causing the release layer to peel off from the substrate, resulting in uneven thickness of the ceramic green sheet. And the breakage of the ceramic green sheet at the part where the release layer is separated from the substrate is likely to occur due to poor peeling, and the yield is reduced.

The rub-off value is a parameter related to the adhesion durability between the release layer and the polyester film as the base material. The lower the rub-off value, the higher the adhesion durability. Specifically, the peeling force between the release layer and the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is laminated or adhered to the release layer surface is measured under a specific condition (under a load of ² N / cm ² ). It is measured before and after rubbing with a friction material (10 reciprocal rubs with a friction material), and is shown as a ratio (P10 / P0) between the peeling force after friction (P10) and the peeling force before friction (P0).
As a friction tester, a Gakushin-type friction bend degree tester is used, and as a friction material, a white polypropylene film is used. The peeling force was measured when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape was adhered to the release layer surface, and was reciprocated once with a 5 kgf pressure rubber roller to make close contact, followed by T-type peeling at a speed of 300 mm / min using Tensilon. Is the measured value.

In order to keep the rub-off value in the above range, it is preferable to complete the curing reaction or the crosslinking reaction of the curable silicone resin constituting the release layer in a short time. For this purpose, there is a method in which the energy required for curing the silicone resin, the amount of catalyst added during the addition reaction, and the like are increased without impairing the operation of the present invention. In the case of an active energy ray-curable silicone resin, it is preferable to increase the crosslink density from the viewpoint of adhesion durability. In particular, since the ultraviolet cation-curable silicone resin uses an epoxy group as a crosslinking group, the adhesion durability to the polyester film is improved as the crosslinking reaction is promoted. Further, in order to improve the adhesion durability between the release layer and the polyester film, before coating the curable silicone resin at the time of forming the release layer, an anchor coat layer is provided on the surface of the antistatic layer, or May be subjected to a pretreatment such as a corona treatment or a flame treatment.

The release film of the present invention has a solid content weight (WA: unit weight) of the binder resin per unit area of the antistatic layer.
g / m ² ), the solid content weight of the antistatic agent (WB: g / m
m ² ) and the solid content weight (WC: g / m ² ) of the curable silicone resin per unit area of the release layer are represented by the following formula 2,
Equation 3 needs to be satisfied. 0.25 ≦ WB / WA ≦ 1.2 Equation 2 0.25 ≦ (WA + WB) /WC≦1.2 Equation 3

When WB / WA is less than 0.25, the antistatic agent is trapped in the binder resin, cannot be present on the surface of the release layer, and the antistatic performance cannot be obtained. On the other hand, when WB / WA exceeds 1.2, the amount of the antistatic agent present on the surface of the release layer is too large to react with the components of the release layer,
Poor curing of the release layer occurs, the siloxane bond of the curable silicone resin of the release layer is broken, the adhesion to the antistatic layer is reduced, and peeling during the formation of the ceramic green sheet using the release film of the present invention is performed. The releasability of the release film from the ceramic green sheet in the process is reduced.

If (WA + WB) / WC is less than 0.25, the thickness of the antistatic layer is too small relative to the thickness of the release layer, and good antistatic performance cannot be obtained on the surface of the release layer. When (WA + WB) / WC exceeds 1.2, the thickness of the antistatic layer is too large relative to the thickness of the release layer, and the antistatic agent hinders the silicone curing of the release layer, and the release layer The adhesion between the layer and the antistatic layer is reduced.

In the release film of the present invention, the curing ratio of the curable silicone resin can be reduced by specifying the ratio of the solid content weight of the binder resin of the antistatic layer, the antistatic agent, and the curable silicone resin of the release layer. An amount of surfactant that does not occur and that exhibits antistatic properties can be present on the surface of the release layer. As a result, the adhesion of the release layer to the polyester film as the base material is improved, and a problem such as a decrease in the peeling force at the time of forming the ceramic green sheet using the release film of the present invention or a back migration property occurs. Without
Problems in the peeling step can be prevented.

Further, in the release film of the present invention, the surface specific resistance value of the release layer is preferably 1 × 10 ¹³ Ω / □ or less, more preferably 1 × 10 ¹¹ Ω / □ or less. Is good. If the surface resistivity of the release layer is 1 × 10 ¹³ Ω / □ or less, even if peeling charging occurs during the formation of the ceramic green sheet, the ceramic green sheet is released from the release layer after the ceramic green sheet is peeled off. No re-adhesion to the mold layer occurs. The surface resistivity of the release layer is 1 ×
When the resistivity is 10 ¹¹ Ω / □ or less, the occurrence of peeling charging does not greatly increase even when the surface specific resistance increases due to the temperature rise during drying of the ceramic slurry when forming the ceramic green sheet. Further, as the surface specific resistance value is smaller, adhesion of dust, dust and the like can be prevented.

The release film of the present invention can be suitably used as a carrier film when forming a ceramic green sheet. When forming the ceramic green sheets, the constituent components of the ceramic green sheets are dispersed in a solvent and applied as a ceramic slurry on a carrier film. The above solvents are roughly classified into an organic solvent type and an aqueous type. When the solvent is an organic solvent-based slurry, the ceramic slurry is prepared by, for example, adding a binder (polyvinyl alcohol, polyvinyl butyral, a polymethyl methacrylate-based polymer and an acrylic polymer) to a dry-milled ceramic raw material (barium titanate), and a plasticizer (phthalate). Acid ester, polyethylene glycol), dispersant (glycerin,
Oleic acid ester) and a solvent. As the solvent, ethanol, isopropyl alcohol, toluene or the like is used. When the solvent is an aqueous slurry, the slurry is adjusted by adding a water-soluble allyl resin to the same ceramic raw material as described above.

The method of applying a ceramic slurry on a carrier film is, for example, in the case of a double-sided coating,
A method of immersing a carrier film in a container containing a ceramic slurry, scraping excess slurry with a metal bar or a doctor blade at the time of lifting, leveling so as to have a uniform thickness, and then evaporating the solvent through a dryer. No. In the case of one-sided coating, a method in which a slurry is flowed on a running carrier film, excess slurry is scraped off with a doctor blade, the slurry is dried to a certain thickness, and dried. In this method, the traveling speed of the carrier film is adjusted, and the thickness of the ceramic green sheet is adjusted in the gap between the doctor blade and the carrier film.

Hereinafter, the present invention will be described in more detail with reference to Test Examples and Examples, but the present invention is not limited thereto. Test example Test method Surface specific resistance value For the release films of Examples 1 to 5 and Comparative Examples 1 to 6,
Using a specific resistance measurement device manufactured by Yuka Electronics Co., Ltd. (Hi testa IP), the temperature of the indoor environment is 25 ° C. × 65%, RH
The surface resistivity of the release layer was measured at 10 points after 30 seconds at a charged voltage of 500 V under the conditions described above, and the average value was defined as the surface resistivity, which was evaluated based on the following criteria. A: Surface specific resistance is 1 × 10 ¹⁰ Ω / □ or less B: Surface specific resistance exceeds 1 × 10 ¹⁰ and 1 × 10 ¹³ Ω
/ □ or less C: Surface specific resistance exceeds 1 × 10 ¹³ Ω / □

(2) Non-Backside Transferability The release films of Examples 1 to 5 and Comparative Examples 1 to 6 were
The test pieces are cut into corners to prepare 10 test pieces, and the test pieces are overlapped so that the release layer surface and the polyester film surface of another test piece are in close contact with each other. Under conditions of a temperature of 25 ° C. and a humidity of 65% RH, 1
After applying and holding a load of 300 kgf for 0 minute, each test piece was separated, written on the polyester film surface using a magic, and the presence or absence of repelling was visually evaluated based on the following criteria. A: No writing at all, good writing (non-backside transferability is good) B: Partially about 1 mm of cissing, but writing is possible (non-backside transferability is somewhat good) C: Magic ink is repelled, Easy to remove with fingers (poor back transferability)

(3) Evaluation of peeling electrification A polyester tape (Nitto 31B) manufactured by Nitto Denko Corporation was applied to the release layer surface of the release films of Examples 1 to 5 and Comparative Examples 1 to 6.
Were bonded under a load of 5 kgf by reciprocating a rubber roller once, and cut into 25 mm width to prepare a test piece. The test piece was held at room temperature (25 ° C. × 50% RH) under no load for 20 hours, and the release film and the polyester tape were separated by 180 ° using a Tensilon tensile tester.
Peeled in the direction at a pulling speed of 500 mm / min, and measured the charged voltage on the side of the peeled polyester tape in an atmosphere of 20 ° C. × 50% RH using a charge meter (Digital Electrostatic Potential Meter KSD-0103 manufactured by Kasuga Electric). Then, the release charge amount on the release film side was evaluated based on the following criteria. A: Charged voltage is 1 kv or less B: Charged voltage exceeds 1 kv and 5 kv or less C: Charged voltage exceeds 5 kv

(4) Formability of release layer When releasing films of Examples 1 to 5 and Comparative Examples 1 to 6 were prepared,
After the formation of the antistatic layer, the state of application when the silicone coating solution for forming the release layer was applied to the surface of the antistatic layer was evaluated based on the following criteria. ：: No repelling or unevenness observed X: Repelled or unevenness observed

(5) Dynamic Hardness The release layer surfaces of the release films of Examples 1 to 5 and Comparative Examples 1 to 6 were measured with a Shimadzu Dynamic Ultra Micro Hardness Tester (DUH-2).
01-202), a triangular cone-shaped indenter with a load of 2 gf was pressed against the surface of the release layer, and the dynamic hardness after holding for 2 seconds was determined by the following equation (7). The measurement was performed 10 times, and the average value thereof was used. Further, the measurement of the dynamic hardness on the surface of the release layer of the release film may be performed on the release film before applying the ceramic slurry to the surface of the release layer to form a ceramic green sheet, or on the ceramic green. This may be performed on the release film after the sheet is formed and the ceramic green sheet is peeled off. P (gf): Test load D (μm): Penetration amount of indenter into sample α: 37.838 Constant by indenter shape (115 ° triangular cone)

(6) Love-off value Gauze as a cushion material on the head portion of a Gakushin type friction kerno degree tester (manufactured by Yamaguchi Kagaku Sangyo Co., Ltd.) and a white polypropylene film (Pearl S, manufactured by Toyobo Co., Ltd.) as a friction material
S, 35 μm in thickness). Examples 1 to 5, the surface of the release layer of the release film of Comparative Examples 1 to 6 and the friction material was overlapped, using the Gakushin friction friction degree tester,
It was rubbed 10 times under a load of ² N / cm ² . The gauze and the friction material were replaced with new ones each time one round of friction was completed. Next, Examples 1 to 5 before and after friction,
An adhesive layer of an adhesive tape (Nitto 31B, manufactured by Nitto Denko Corporation) was adhered to the surface of the release layer of each of the release films of Comparative Examples 1 to 6, and was reciprocated once with a 5 kgf pressure rubber roller to adhere. After 2 hours, 300 mm using Tensilon
T-peel at a speed of / min, and measure the peeling force between the release layer of the release film and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape. Ratio (P10 /
P0) was determined and used as a rub-off value. The obtained rub-off value was evaluated based on the following criteria. A: 5.0 or less B: More than 5.0, 10.0 or less C: More than 10.0

(7) Releasability of ceramic green sheet Mixed solvent (weight ratio: toluene / ethanol = 50/5)
0) in the ceramic particles (average primary particle diameter is 0.6 μm)
Barium titanate (BaTiO ₃ ) manufactured by Fuji Titanium Co., Ltd.)
100 parts by weight are mixed and the particle size of the media is 1.5 mm
With a zirconia bead (filling amount: 200% by weight based on the slurry) in a ball mill for 2.4 hours. Next, 10 parts by weight of a binder (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) and a plasticizer (polyethylene glycol) were mixed at 2% by weight based on the total amount of the ceramic powder and the binder, dispersed by a ball mill for 24 hours, and further filtered ( Filtration was performed with a pore size of 3 μm) to obtain a paste-like ceramic slurry.

The release films of Examples 1 to 5 and Comparative Examples 1 to 6 in the form of rolls were unwound, and the release of the release films was carried out using a doctor blade so that the thickness of the ceramic slurry after drying became 30 μm. Apply to mold layer surface, 120 ℃
For 1 minute to provide a ceramic sheet layer (weight ratio of ceramic particles / binder: 100/10) to obtain a film laminate for producing a ceramic green sheet. 5c of the above film laminate for producing a ceramic green sheet
Cut to m width, a polyester adhesive tape (Nitto 31B, manufactured by Nitto Denko Corporation) is adhered to the ceramic sheet layer surface, and a peeling method (peeling rate: 500 mm / min, T-type peeling)
To separate the ceramic sheet layer from the release film, thereby obtaining a ceramic green sheet. The entire surface of the obtained ceramic green sheet was visually observed for damage such as pinholes and tears, and evaluated based on the following criteria. The test was performed five times. A: No damage was observed on the ceramic green sheet in all five times. B: At least one out of five times, a part of the ceramic green sheet is damaged. C: The ceramic green sheet is broken at least once out of five times.

Test Results In the release films of Examples 1 to 5 and Comparative Examples 1 to 6,
Solid weight of binder resin per unit area of antistatic layer (WA: g / m ² ), solid weight of antistatic agent (WB: g / m ² ), curability per unit area of release layer Table 1 shows the solid content weight (WC: g / m ² ), WB / WA, and (WA + WB) / WC of the silicone resin. Table 2 shows the results of the tests (1) to (7).

The release films of Examples 1 to 5 have a dynamic hardness of 8.0 gf / μm ² or more, and the antistatic agent and the binder contained in the antistatic layer adversely affect the silicone curing of the release layer. It has excellent non-backside transferability and adhesion durability (rub-off value) of the release layer. In addition, since the surface resistivity of the release layer is low and the peeling charge is small, even when the ceramic green sheet is peeled from the release film, the ceramic green sheet does not re-adhere easily even when forming the ceramic green sheet. Peeled off. On the other hand, since the release film of Comparative Example 1 does not have an antistatic layer, the release charge at the time of peeling the ceramic green sheet is large. Since the release film of Comparative Example 2 has a thick release layer,
The antistatic effect of the antistatic agent does not extend to the surface of the release layer, and although the releasability is good, the release charge is large. Since the thickness of the antistatic layer of the release film of Comparative Example 3 was small, the antistatic effect was not sufficient, and the release charge on the surface of the release layer was large. In the release film of Comparative Example 4, since the thickness of the antistatic layer was large, the antistatic agent hindered the silicone curing of the release layer, and formed the release layer, the adhesion of the release layer, and the time of forming the ceramic green sheet. Is insufficient in releasability. In the release film of Comparative Example 5, the content of the antistatic agent in the antistatic layer was small, and the effect of the antistatic agent was not obtained. The release film of Comparative Example 6 has a high ratio of the antistatic agent in the antistatic layer, and thus inhibits silicone curing of the release layer, and has release layer forming properties, release layer adhesion, and ceramic green sheets. The peelability during formation is poor.

[0055]

EXAMPLE 1 0.6 parts by weight of a quaternary ammonium salt (PQ-10, Soken Chemical Co., solution concentration 50%) as a cationic antistatic agent, polyvinyl butyral (trade name, manufactured by Sekisui Chemical Co., Ltd.) ESREC BL-1) 0.3 parts by weight, ethanol 9
9.1 parts by weight were mixed to prepare a coating solution for forming an antistatic layer, which was applied to one surface of a 38 μm-thick biaxially stretched polyethylene terephthalate film (E5151 manufactured by Toyobo Co., Ltd.) formed by a conventional method. By wire bar,
Coating was performed so that the coating amount after drying was 0.03 g / m ^2, and the coating was dried in a hot-air dryer at 90 ° C. for 30 seconds to form an antistatic layer. Next, a thermosetting silicone resin (KS-830, manufactured by Shin-Etsu Chemical Co., Ltd.) was diluted with a solvent (toluene) so that the thermosetting silicone resin had a concentration of 3% by weight, and 1 part by weight based on 100 parts by weight of the silicone resin. Of a platinum catalyst were added to prepare a coating liquid for forming a release layer. The coating liquid for forming a release layer is applied on the surface of the antistatic layer with a wire bar so that the coating amount after drying is 0.10 g / m ^2, and dried at 100 ° C. for 30 seconds to obtain a release film. Was.

Example 2 An ultraviolet cation-curable silicone resin (XS56-A1652 manufactured by Toshiba Silicone Co., Ltd.) was dissolved in a solvent (normal hexane) so that the concentration of the ultraviolet cation-curable silicone resin was 2% by weight.
1 part by weight of bis (alkylphenyl) per 0 parts by weight
Iodonium hexafluoroantimonate was added as a curing catalyst to prepare a coating liquid for forming a release layer. Example 1
The same antistatic layer was formed in the same manner as in Example 1, and the same coating liquid for forming a release layer was applied to one surface of a 38-μm-thick biaxially stretched polyethylene terephthalate film (manufactured by Toyobo Co., Ltd.) using a wire bar. After applying and drying at 100 ° C. for 30 seconds, ultraviolet ray irradiation (300 mJ /
cm ² ), and the coating amount of the release layer after drying is 0.10 g / m ^2.
Was obtained.

Example 3 Except that the coating amount of the antistatic layer was 0.10 g / m ² ,
A release film was obtained in the same manner as in Example 1.

Example 4 When preparing a coating solution for forming an antistatic layer, a quaternary ammonium salt (PQ- manufactured by Soken Chemical Co., Ltd.) was used as a cationic antistatic agent.
10, solution concentration 50%) except for 0.2 parts by weight.
A release film was obtained in the same manner as in Example 1.

Example 5 At the time of preparing the coating solution for forming the antistatic layer, polyvinyl butyral (Eslec BL-1 manufactured by Sekisui Chemical Co., Ltd.) was added in an amount of 0.4%.
A release film was obtained in the same manner as in Example 1 except that the amount was changed to parts by weight.

Comparative Example 1 Thermosetting Silicone Resin (KS, manufactured by Shin-Etsu Chemical Co., Ltd.)
-830) is diluted with a solvent (toluene) to a concentration of 3% by weight of the thermosetting silicone resin, and 1 part by weight of a platinum catalyst is added to 100 parts by weight of the silicone resin to form a coating liquid for forming a release layer. It was created. The coating amount after drying the release liquid for forming the release layer is 0.10 g with a wire bar on one side of a 38 μm-thick biaxially stretched polyethylene terephthalate film (E5151 manufactured by Toyobo Co., Ltd.) formed by an ordinary method. / M ² and at 100 ° C for 30
After drying for 2 seconds, a release film was obtained.

Comparative Example 2 A release film was obtained in the same manner as in Example 1, except that the coating amount of the release layer was changed to 0.5 g / m ² .

Comparative Example 3 Except that the coating amount of the antistatic layer was 0.02 g / m ² ,
A release film was obtained in the same manner as in Example 1.

Comparative Example 4 A release film was obtained in the same manner as in Example 1 except that the coating amount of the antistatic layer was changed to 0.2 g / m ² .

Comparative Example 5 A quaternary ammonium salt (PQ- manufactured by Soken Chemical Co., Ltd.) was used as a cationic antistatic agent when preparing a coating solution for forming an antistatic layer.
10, solution concentration 50%) was changed to 0.1 part by weight,
A release film was obtained in the same manner as in Example 1.

Comparative Example 6 A quaternary ammonium salt (PQ- manufactured by Soken Chemical Co., Ltd.) was used as a cationic antistatic agent when preparing a coating solution for forming an antistatic layer.
10, solution concentration 50%) was changed to 1.0 part by weight.
A release film was obtained in the same manner as in Example 1.

[0066]

The release film of the present invention has a small peeling charge, a large dynamic hardness (DH) of the release layer, an antistatic property and an adhesion to the polyester film which is a substrate of the release layer. Is excellent in a good balance, the peeling force at the time of peeling is small, and it is possible to peel off the release film from the ceramic green sheet with a force that does not cause peeling failure, especially in the peeling step at the time of manufacturing the ceramic green sheet. There is no trouble of reattaching later. Further, peeling failure due to peeling of the peeling layer from the antistatic layer is also prevented. Furthermore, by having a release layer on the antistatic layer, the backside transfer to the antistatic layer release layer by storing the release film in a roll shape, and to the roll by the contact of the roll in the ceramic green sheet forming process Contamination due to the adhesion of the antistatic layer is prevented. Therefore,
It is suitable for the production of a ceramic green sheet, particularly a thin ceramic green sheet, as a carrier film for molding.

[Table 1]

[Table 2]

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B32B 27/18 B32B 27/18 D (72) Inventor Harunobu Kuroiwa 2-8-8 Dojimahama, Kita-ku, Osaka-shi, Osaka Toyo Spinning Co., Ltd. In-house F-term (Reference) 4D075 AE03 CA07 CA13 CA22 DA04 DB48 DC19 DC40 EB19 EB43 EB56 EC07 EC37 EC54 4F100 AB24 AH03 AK01B AK02B AK23 AK41A AK42 AK52C AS00B BA03 BA10A BA10C J15 J05B12 JBJJJB12 YY00C 4G052 DA02 DB10

Claims (5)

[Claims] 1. A release film having an antistatic layer mainly composed of a binder resin and an antistatic agent on at least one surface of a polyester film, and having a release layer mainly composed of a curable silicone resin on the antistatic layer. Wherein the dynamic hardness (DH) of the release layer is expressed by the following formula 1.
And the solid content weight (WA: g / g) of the binder resin per unit area of the antistatic layer.
m ² ), the solid content weight of the antistatic agent (WB: g / m ² ) and the solid content weight of the curable silicone resin per unit area of the release layer (WC: g / m ² ) And a release film satisfying Formula 3. DH ≧ 8.0 (gf / μm ² ) Equation 1 0.25 ≦ WB / WA ≦ 1.2 Equation 2 0.25 ≦ (WA + WB) /WC≦1.2 Equation 3 2. The release film according to claim 1, wherein the antistatic agent is a cationic antistatic agent. 3. The release film according to claim 1, wherein the binder resin is a polyvinyl resin. 4. The release film according to claim 1, wherein the release layer is formed by crosslinking the siloxane compound using a metal catalyst. 5. The laminated film according to claim 1, which is for forming a ceramic green sheet.