JP2005047176A - Release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a release film for suppressing the peeling charge of a thin formed sheet and producing no pinhole or rupture in the formed sheet. <P>SOLUTION: This release sheet is composed of a polyester film and the silicone release layer having a peeling charge suppressing function provided at least on one side thereof, and the peel force thereof is 0.5-50 g/25 mm width. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a release film used as a carrier sheet for sheet molding. More specifically, the present invention relates to a release film used as a carrier sheet capable of suitably producing a ceramic sheet, a resin sheet, and an electrode sheet.

  In recent years, with the miniaturization of electronic devices, the development and miniaturization of various electronic materials have been remarkably developed. In particular, the growth in usage due to miniaturization and low power consumption of mobile communication devices is remarkable.

  Conventionally, a ceramic capacitor as such an electronic material is a slurry in which ceramic powder, a solvent, a binder and other additives (plasticizer, dispersant, antistatic agent, etc.) are uniformly dispersed by an appropriate mechanical dispersion method. Is applied onto a carrier sheet by a cast casting method, and then dried to produce a ceramic green sheet. An internal electrode is printed on the sheet, and a sheet cut into a predetermined size is laminated, sintered, and externally coated. It was manufactured by attaching electrodes. However, as the size and capacity of products have increased, sheet molding of 3 μm or less has become necessary. For this reason, the surface of the polyester film to be used is required to be smooth, and it has become necessary to lightly release the silicone as a release agent.

Conventionally, a smooth polyester film has been used to deal with such problems. However, the smoother the film, the higher the friction and peeling charge in the process, and the higher the release layer. When the formed thin film sheet is peeled off, there is a problem that peeling electrification occurs and the peeling force becomes heavy. Therefore, a method of adding an antistatic agent such as an ion-conducting quaternary ammonium salt to the silicon resin layer has been adopted, but the ionic component during the antistatic reaction with a platinum catalyst that is a silicone curing catalyst. As a result, the silicone film curing reaction is hindered.
JP-A-60-141553

  An object of the present invention is to provide a release film that improves the drawbacks of the prior art, suppresses peeling electrification of a thin-layer molded sheet, and does not cause pinholes or tears in the molded sheet.

  That is, the present invention comprises a polyester film and a silicone release layer having a peeling charge suppressing function provided on at least one surface thereof, and the peeling force is 0.5 g / 25 mm width to 50 g / 25 mm width. It is a release film.

Hereinafter, the present invention will be described in detail.
[Polyester film]
The polyester in the present invention is a polyester having an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. This polyester is substantially linear and has film-forming properties, particularly film-forming properties by melt molding. Examples of the aromatic dicarboxylic acid include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, diphenylether dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenylketone dicarboxylic acid, anthracene dicarboxylic acid. Etc. Examples of the aliphatic glycol include polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, diethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, and 1,4-cyclohexanediethylene. Examples include alicyclic diols such as methanol.

  Among these polyesters, particularly polyethylene terephthalate and polyethylene-2,6-naphthalate, for example, 80 mol% or more of the total dicarboxylic acid component is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and the total glycol component A copolymer in which 80 mol% or more of the polymer is ethylene glycol is preferable. In this case, 20 mol% or less of the total acid component can be the above aromatic dicarboxylic acid other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid. An alicyclic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. Further, 20 mol% or less of the total glycol component may be the above-mentioned glycol other than ethylene glycol, and aromatic diols such as hydroquinone, resorcin, 2,2-bis (4-hydroxyphenyl) propane, etc .; 1,4 -An aliphatic diol having an aromatic ring such as dihydroxydimethylbenzene; polyalkylene glycol (polyoxyalkylene glycol) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like.

  The polyester in the present invention includes, for example, a component derived from an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid and an aliphatic oxyacid such as ω-hydroxycaproic acid, a dicarboxylic acid component and an oxycarboxylic acid component. Those which are copolymerized or bonded in an amount of 20 mol% or less based on the total amount of the above are also included.

  Furthermore, the polyester in the present invention has an amount in a substantially linear range, for example, an amount of 2 mol% or less based on the total acid component, and a trifunctional or higher polycarboxylic acid or polyhydroxy compound such as trimellitic acid, A copolymer of pentaerythritol and the like is also included.

  The polyester is preferably composed mainly of alkylene terephthalate and / or alkylene-2,6-naphthalate.

  Polyesters are known per se and can be produced by methods known per se. The polyester preferably has an intrinsic viscosity of 0.4 to 0.9 determined as a solution in o-chlorophenol at 35 ° C., more preferably 0.5 to 0.7, and The thing of 55-0.65 is especially preferable.

  For the polyester film, organic or inorganic fine particles having an average particle size of about 0.01 to 25 μm, preferably about 0.01 to 2 μm, for example, 0.005 are used as a lubricant to make the film slippery. It can be contained at a blending ratio of ˜2% by weight, preferably 0.05 to 0.5% by weight.

  Specific examples of such fine particles include inorganic particles such as calcium carbonate, kaolin, silicon oxide, and barium sulfate, and organic particles such as crosslinked polystyrene resin particles, crosslinked silicone resin particles, and crosslinked acrylic resin particles. Alternatively, by depositing fine particles from the catalyst residue used in the polyester synthesis reaction, fine irregularities can be formed on the film surface, and the slipperiness of the film can be improved.

  In the double-sided release film of the present invention, the surface roughness Ra on both sides of the double-sided release film is preferably 1 to 50 nm, more preferably 5 to 40 nm, and particularly preferably 8 to 30 nm by the addition of the lubricant. When the surface roughness Ra is less than 1 nm, the handling characteristics are extremely deteriorated and the productivity is deteriorated. If it exceeds 50 nm, irregularities are generated on the surface of the molded sheet, and the sheet thickness unevenness adversely affects the quality.

  In the present invention, these fine particles are preferably subjected to particle size adjustment and coarse particle removal using a purification process before being added to the polyester. Examples of the industrial means of the purification process include a dry or wet centrifugal method and an air classification method. In addition, it is particularly preferable that these means are used in combination of two or more and purified stepwise.

  The polyester film in the present invention can be produced by a conventionally known method. For example, the biaxially stretched polyester film is obtained by drying the polyester, melting it in an extruder, extruding it from a die (for example, T-die, I-die, etc.) onto a rotating cooling drum, quenching it into an unstretched film, It can manufacture by extending | stretching this unstretched film to a biaxial direction, and heat-setting as needed. The thickness of the film is not particularly limited, but is preferably 5 to 250 μm.

[Silicone release layer]
In the present invention, each silicone release layer is formed of a curable silicone resin. As the curable silicone resin, those generally known as mold release agents can be used, for example, selected from known ones described in “Silicon Material Handbook” (Toray Dow Corning, 19933.8). can do. Examples thereof include KS-847 (H) and KS-776 manufactured by Shin-Etsu Silicone Co., Ltd., and TPR-6700 manufactured by Toshiba Silicone Co., Ltd. As these curing methods, a heat or radiation curing type is common. Specifically, the following curing methods are mentioned.
(1) Thermal condensation reaction type: A product obtained by reacting silanol functional dimethylpolysiloxane at both ends with methylhydrogenpolysiloxane or methylmethoxysiloxane in the presence of an organotin catalyst.
(2) Thermal addition reaction type: A product obtained by reacting methyl vinyl polysiloxane having vinyl groups at both ends or both ends and side chains of a molecular chain with methyl hydrogen polysiloxane in the presence of a platinum catalyst.
(3) Ultraviolet curing type (radical addition type): A siloxane containing an alkenyl group and a mercapto group, with a photopolymerization agent added.
(4) Ultraviolet curing type (hydrosilyl type): A catalyst using the same platinum-based catalyst as the thermal addition reaction type.
(5) Ultraviolet curing type (radical polymerization type): A siloxane containing a (meth) acryl group and a photopolymerization agent added thereto.
(6) UV curable type (cationic polymerization type): An onium salt photoinitiator added to a siloxane containing an epoxy group.
(7) Electron beam curable type: radically polymerizable group-containing siloxane (no functional group or photoinitiator).

  The form of the curable silicone resin can be appropriately selected from a solvent type, an emulsion type, a solventless type, and the like.

  Various known additives can be blended in the release layer in the present invention as long as the object of the present invention is not hindered. As this additive, an ultraviolet absorber, a pigment, an antifoamer, a pot life extending agent, a crosslinking agent etc. can be mentioned, for example.

  In the present invention, a silicone release layer is provided on at least one surface of the polyester film.

  For example, the release layer is formed by applying a coating liquid containing a polydimethylsiloxane having a vinyl group represented by the following formula (A), a hydrogensilane compound represented by the following formula (B), and a Pt compound to the film. It can be provided by heating, drying and curing reaction. The heating condition is preferably, for example, 80 to 160 ° C. for 10 to 120 seconds, particularly 100 to 150 ° C. for 15 to 60 seconds, because the drying and curing reaction is sufficient.

  In the above formula (A), m and n are numbers of 1 or more, but if m is in the range of 1 to 100, n is in the range of 20 to 5000, and m + n is in the range of 30 to 5000, the crosslinking reaction proceeds favorably and durability This is preferable because it is a layer with a thickness of about 10 nm.

  In the above formula (B), a and b are numbers of 1 or more, but if a is in the range of 3 to 200, b is 1 to 20, and 5 ≦ a + b ≦ 200, the crosslinking reaction proceeds favorably and durability Since it becomes a layer with the property, it is preferable.

  It should be noted that the number of repeating units m, n, a, b (see below) in the above formulas (A) and (B) does not mean block coupling, but these are simply the sum of the respective units m, n Or it should be understood that it is only showing that it is a and b. Accordingly, the units in the above formulas (A) and (B) may be randomly bonded or may be block bonded.

Further, the silicone of the silicone release layer is preferably added with a silane compound represented by the following formula.
(R1) ₃ -Si-R3
(R1-O) _3- Si-R3
(R1-0-R2) ₃ -Si-R3
(However, R1 and R2 are each a chain alkyl group having 1 to 5 carbon atoms, and R3 is a vinyl group or a phenyl group.)
The addition amount of the silane compound is preferably 1 to 5 parts by weight with respect to 100 parts by weight of the silicone resin.

  In addition, as a coating method of the coating liquid for providing the silicone release layer, any known coating method can be applied, and examples thereof include a roll coater method and a blade coater method. Each coating may be applied and is not limited to these methods. The coating solution may be a coating solution using an organic solvent or an aqueous coating solution, but is preferably a solution in which polydimethylsiloxane or a hydrogensilane compound is dissolved, such as toluene. A coating liquid using an organic solvent is preferable.

  The release force of the silicone release layer is required to be 0.5 g / 25 mm width to 50 g / 25 mm width with a 25 mm width peel force with an acrylic adhesive tape (Nitto Denko Corporation: 31B tape). When the peeling force is less than 0.5 g / 25 mm width, the thin film molded sheet is easily peeled off from the release film and the handling property becomes insufficient. When the peeling force exceeds 50 g / 25 mm width, when the thin layer sheet is peeled, an extra tensile load is required and the thin layer sheet is torn.

In the present invention, the silicone release layer has a peeling charge suppressing function. This function is a function of suppressing peeling charge, and is imparted to the silicone release layer by containing 0.2 to 10% by weight of polyalkylene oxide per silicone release layer. This polyalkylene oxide is generally represented by HO (RO) _n H. R is preferably a chain alkyl group, preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms. n is preferably 1 to 10, more preferably 1 to 6. The molecular weight is preferably 200 to 4000, more preferably 200 to 600.

  The content of the polyalkylene oxide is preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the silicone resin. When the amount of polyalkylene oxide is less than 0.2 parts by weight, the antistatic effect is insufficient, which is not preferable, and when the amount exceeds 10 parts by weight, the polyethylene glycol works as a plasticizer and does not deteriorate the catalytic activity. Is not preferable.

  In addition, when mix | blending as a solution when mix | blending a polyalkylene oxide, it is preferable to use a nonionic solution. If it is nonionic, there is nothing that reacts with the platinum catalyst, which is a silicone curing catalyst, and it does not become a catalyst poison, and the silicone film is sufficiently cured.

[Anchor coat layer]
In this invention, in order to improve the adhesiveness of a polyester film and a silicone release layer, it is preferable to provide an anchor coat layer between a polyester film and a silicone release layer. By providing the anchor coat layer, silicone transfer of the silicone release layer can be suppressed.

As such an anchor coat layer, a silane coupling agent can be preferably used. Examples of the silane coupling agent include those represented by the general formula Y—Si—X ₃ . Here, Y represents a functional group represented by an amino group, an epoxy group, a vinyl group, a methacryl group, or a mercapto group, and X represents a hydrolyzable functional group represented by an alkoxy group. The thickness of the anchor coat layer is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm. Furthermore, in forming the anchor layer, it is preferable to provide the anchor layer before biaxial stretching in the biaxial stretching film forming step.

  ADVANTAGE OF THE INVENTION According to this invention, the release charge of a thin layer molded sheet can be suppressed, and the release film which a pinhole and a tear do not arise in a molded sheet can be provided.

Hereinafter, the present invention will be described in detail by examples. In the examples, “part” means “part by weight”. The physical property values and characteristic values in the present invention were measured by the following methods.
(1) Peel strength A polyester pressure-sensitive adhesive tape (Nitto 31B) was bonded to the release layer surface of the film and pressed with a 5 kg pressure roller, and the peel force between the release layer and the pressure-sensitive adhesive tape was measured with a tensile tester.
(2) Residual Adhesion Rate The peel force after the polyester adhesive tape (Nitto 31B) was attached to a cold rolled stainless steel plate (SUS304) specified in JIS G4305 was measured and used as the basic adhesive force (f ₀ ). The polyester adhesive tape was bonded to the surface of the release layer of the sample film, pressed with a 5 kg pressure roller, allowed to stand for 30 seconds, and then peeled off. And this peeled adhesive tape was affixed on said stainless steel plate, the peeling force of this bonding part was measured, and it was set as the residual adhesive force (f). The residual adhesive rate was calculated | required using the following formula from the obtained basic adhesive force and residual adhesive force.
Residual adhesion rate (%) = (f / f ₀ ) × 100
A release film having a residual adhesion rate of 85% or more is preferable, and when it is less than 85%, the amount of silicone transferred is large, and stability over time is applied.
(3) Surface resistance value The surface resistance value was measured with a measuring instrument (R8340 / R12704) manufactured by Advantest Corporation. The measurement environment was a sample that was aged for 24 hours at 23 ° C. and 55%, and measured with the above apparatus. The surface resistance value was evaluated according to the following criteria.
10 ¹⁴ or more: ×
Less than 10 ¹⁴ : ○
(4) Smear test / Love off test Smear test The release surface was rubbed once with an index finger, and the whitening state of the surface was visually observed and evaluated according to the following criteria.
○ No change △ Slightly whitening × Whitening rub-off test The mold release surface was rubbed 10 times with the thumb, and in order to confirm that the silicone had fallen off, the peeled state was confirmed with cello tape and evaluated according to the following criteria.
○ No peeling change when peeling tape × No peeling change when peeling tape

[Examples 1-2, Comparative Examples 1-3]
Add dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and silicon oxide particles (0.3μ, 0.2% by weight) as a lubricant. Then, polymerization was carried out by a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity (o-chlorophenol) of 0.56. The polyethylene terephthalate pellets were dried at 170 ° C. for 3 hours, then supplied to an extruder hopper, melted at a melting temperature of 280 to 300 ° C., extruded onto a rotary cooling drum having a surface finish of 0.3 s and a surface temperature of 20 ° C. An unstretched film was obtained. The unstretched film thus obtained is preheated to 75 ° C., and further heated by three IR heaters having a surface temperature of 800 ° C. from 15 mm above between low-speed and high-speed rolls and stretched 3.2 times. Then, it was rapidly cooled, then supplied to a stenter, and stretched 4.3 times in the transverse direction at 120 ° C. The obtained biaxially oriented film was heat-set at a temperature of 230 ° C. for 5 seconds to obtain a heat-fixed biaxially oriented polyester film having a thickness of 38 μm. At that time, the thickness of the film after biaxial stretching and orientation treatment is always measured online in the width direction, and the result is fed back to adjust the temperature of the lip heater of the extrusion die and change the resin fluidity. A system to eliminate the spots was used. In the film forming step, 3-glycidoxypropyltrimethoxysilane is used as an anchor coat layer of a release layer on one side of the polyester film at a position immediately before the uniaxially stretched film that has been longitudinally stretched enters transverse stretching. A 3 wt% aqueous solution (containing a surfactant) was applied in an amount of 5 g / m ² (wet) and dried.
Ra of the obtained film was 9 nm and Rz was 152 nm.

Then, on the surface of this anchor coat layer, a curable silicone resin of a type in which a platinum catalyst is added to a mixed solution of polydimethylsiloxane and dimethylhydrogensilane to cause an addition reaction is dissolved in a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene. The applied silicone resin coating solution was applied. The drying temperature was 130 ° C. for 30 seconds to obtain a double-sided release film as shown in Table 1.
Table 2 shows the characteristics of the carrier sheet which is a double-sided release film.

Claims (5)

  A release film comprising a polyester film and a silicone release layer having a release charge suppressing function provided on at least one surface thereof, and having a release force of 0.5 g / 25 mm width to 50 g / 25 mm width.   The release film according to claim 1, wherein the silicone release layer contains 0.2 to 10 parts by weight of polyalkylene oxide per 100 parts by weight of the silicone resin. The release film according to claim 1, wherein the release film has a surface resistance value of less than 10 ¹⁴ Ω / □.   The release film of Claim 1 whose surface roughness (Ra) of a release film is 1-50 nm. The release film according to claim 1, wherein a silane compound represented by the following formula is added to the silicone release layer.
(R1) ₃ -Si-R3
(R1-O) _3- Si-R3
(R1-0-R2) ₃ -Si-R3
(However, R1 and R2 are each a chain alkyl group having 1 to 5 carbon atoms, and R3 is a vinyl group or a phenyl group.)