JP4183962B2 - Release film - Google Patents

Description

上記表中、ＲＡ８０はアシオレジンＲＡ−８０(アシオ産業（株）製）、ＲＡ９５はアシオレジンＲＡ−９５Ｈ（アシオ産業（株）製）である。
【００２２】
【発明の効果】
本発明の離型フィルムは、薄層グリーンシートの工程フィルムとして好適であり、その工業的価値は非常に高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release film, and in particular, relates to a release film that is suitably used for forming a green sheet.
[0002]
[Prior art]
Conventionally, as a carrier film for forming a green sheet of a ceramic multilayer capacitor, a release film in which a polyester film is used as a base material and a silicone compound such as polysiloxane is laminated is used. In recent years, ceramic green sheets themselves have been made thinner with the miniaturization of capacitors accompanying the miniaturization of electronic devices.
Under such circumstances, problems such as breakage of the green sheet frequently occur at the time of slurry repelling, pinhole generation, and green sheet peeling at the time of ceramic slurry coating, and improvement is required.
In addition, when a release layer is installed and wound, problems such as blocking and deterioration in the transportability of the release film may occur, and variations in dielectric constant when electrodes are provided on both sides of the ceramic layer to form a capacitor. There is a need for a release film that can improve these properties, such as increasing the thickness.
Furthermore, since the siloxane-based low molecular weight substance is disliked depending on the use, it is desired that the release layer is other than the silicone compound.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and the problem to be solved is, for example, when it is used as a carrier film for forming a green sheet of a ceramic multilayer capacitor, the repelling of the slurry during the coating of the ceramic slurry and the occurrence of pinholes An object of the present invention is to provide a release film using a release layer other than the silicone compound by eliminating problems such as breakage of the green sheet when the green sheet is peeled off.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be easily solved by a release film having a specific configuration, and have completed the present invention.
[0005]
That is, the gist of the present invention is that the center plane average roughness (SRa (A)) of a surface (A surface) composed of a release layer composed of a long-chain alkyl group-containing polymer is 20 nm or less, and the normal state peeling force is 150 mN / The release film is characterized by having a center plane average roughness SRa (B) of 10 to 50 nm on the other film surface (B surface).
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The polyester referred to in the present invention is a compound having a plurality of carboxyl groups and hydroxyl groups, for example, polyvalent carboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid and pyromellitic acid, and many compounds such as ethylene glycol and tetramethylene glycol. It is a polymer obtained by polycondensation of a monohydric alcohol or a hydroxycarboxylic acid such as p-hydroxybenzoic acid. Polyethylene terephthalate, which is widely used as a film material, is also a typical example of polyester.
As a catalyst for polycondensation of polyester, antimony trioxide is usually used, but ionic impurities may be by-produced, and germanium such as germanium dioxide is used from the viewpoint of reducing transfer to the adherend. It is recommended to polymerize with a catalyst system such as a compound, a titanium compound such as tetrabutyl titanate, or a composite system thereof.
[0007]
The film used in the present invention can be obtained by conventional methods such as extrusion molding and casting, but from the viewpoint of heat resistance, it may be stretched and heat-set as necessary after being formed into a sheet. preferable.
In the release film of the present invention, the center plane average roughness SRa (A) of the surface (A surface) of the release layer is 20 nm or less, preferably 10 nm or less. When SRa (A) exceeds 20 nm, slurry coating properties such as repellency and dropout are insufficient at the time of forming a green sheet, which is not preferable.
In the release film of the present invention, the center surface average roughness SRa (B) of the surface opposite to the A surface (B surface) is 10 to 50 nm, preferably 15 to 30 nm. When SRa (B) is less than 10 nm, problems such as blocking and deterioration of transportability may occur, which is not preferable. If SRa (B) exceeds 50 nm, transfer of the C-plane surface protrusion to the A-plane, so-called show-through occurs, and SRa (A) is set to 10 nm or more, which is not preferable.
[0008]
As a method for setting SRa (A) and SRa (B) in such a range, a polyester film as a base material has a two-layer structure, and each layer has inert fine particles such as silica, calcium carbonate, kaolin, titanium oxide, and aluminum oxide. In addition, inorganic particles such as barium sulfate and zeolite, or organic particles such as crosslinked polystyrene and acrylic resin may be used alone or in a mixture to blend them in an appropriate amount to use a method for designing each surface roughness. It is done. In this case, the average particle size, the amount added, and the particle size distribution of the particles used are not particularly limited as long as they do not depart from the gist of the present invention, but the average particle size is 0.1 to 4.0 μm. It is preferable that the range and addition amount are in the range of 0.01 to 3.0% by weight, and that the particle size distribution has a small dispersion.
In addition to the layers constituting each surface, one or a plurality of intermediate layers can be provided. In this case, since there is no restriction such as the formation of specific surface roughness in the intermediate layer, it does not contain various fillers substantially, and it is also possible from the industrial point of view to reduce foreign matter and production costs caused by the added filler. desirable.
[0009]
The A surface of the release film of the present invention comprises a layer composed of a long chain alkyl group-containing polymer. Examples of the long-chain alkyl group-containing polymer include polyolefins and polymers in which a long-chain alkyl group side chain is bonded to a main chain mainly composed of a methylene structure. From the viewpoint of adhesion to the base film, a polymer having a long-chain alkyl group side chain, in which the long-chain alkyl group side chain is bonded to the main chain by an ester bond is particularly recommended. By having an ester bond, the adhesion to the base polyester film is improved. Examples of the ester bond include carboxylic acid esters and carbamic acid esters. That is, polyalkyl (meth) acrylate, polyvinyl alkyl carbamate, and those obtained by copolymerizing other polymerized units are suitable. As the long-chain alkyl group serving as the side chain, a polymethylene group having 10 to 22 carbon atoms is preferable because of its low surface energy and good releasability. If necessary, these polymers may be chemically modified so that crosslinking treatment such as UV curing and heat curing is possible, and solvent resistance may be imparted.
[0010]
The release film of the present invention has a peel force on the release surface of 150 mN / cm or less, preferably 100 mN / cm or less. A peeling force exceeding 150 mN / cm is not preferable because it is not suitable for light peeling applications. The lower limit of the peeling force is usually 5 mN / cm.
Note that the release layer is likely to cause cohesive failure, and the peeling force is small because it peels off. This does not meet the gist of the present invention. Therefore, the above-mentioned normal peeling force has a residual adhesion rate of 80% or more, preferably 90%. It is desired to be realized on the basis of% or more.
Examples of the method for forming the long-chain alkyl group-containing polymer release layer on the surface of the base film include a hot melt method, a coating method, and a coextrusion method. In the case of the coating method, use the reverse roll coater, gravure coater, rod coater, air doctor coater or other coating device shown in “Coating Method” by Yuji Harasaki, Tsuji Shoten, 1979, The method of apply | coating a coating liquid outside a film manufacturing process and the method of apply | coating within a film manufacturing process are mentioned.
[0011]
The release layer may be formed only on one side of the base film, or may be formed on both sides. When it is formed on only one side, a layer such as a slippery layer or an antistatic layer may be formed on the opposite side as necessary. Moreover, you may provide intermediate | middle layers, such as an easily bonding layer and an antistatic layer, between a base film and a mold release layer. Furthermore, if necessary, the surface of the base film may be subjected to easy adhesion treatment such as corona discharge treatment.
The thickness of the release layer is usually 10 nm or more, preferably 50 nm or more. When the thickness of the release layer is less than 10 nm, it may be difficult to obtain a uniform layer, and the peelability may be deteriorated. On the other hand, the upper limit is not particularly limited, but it is recommended that the upper limit is 10 μm or less because it is a cause of cost increase if it is too thick, and in some cases slipperiness is lowered at 10 μm or more.
In the release film of the present invention, various stabilizers, ultraviolet absorbers, antioxidants, plasticizers, anti-packaging agents, coatability improvers, thickeners, as necessary, within a range that does not impair the gist of the invention. Surfactants, lubricants, dyes, pigments, polymer compounds and the like may be added.
[0012]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. In the examples and comparative examples, “parts” means “parts by weight” as a solid content.
[0013]
(1) Measurement of center plane average roughness Non-contact type three-dimensional roughness meter (manufactured by Micromap Co., Ltd.) by depositing Al on the surface of a 3 cm square film sample and using direct phase detection interferometry, so-called two-beam interferometry. 512), measuring the center plane average roughness SRa of the film surface in a measurement region of 232 μm × 177 μm over 50 points under the conditions of the measurement wavelength: 554 nm and the objective lens magnification: 20 times, The SRa of the film was calculated by averaging the SRa values at 50 points.
[0014]
(2) Evaluation of slurry coatability A ceramic slurry having the following composition was applied on the film surface so as to be 5 μm in a wet state, and the slurry coatability at that time was determined according to the following criteria.
<Ceramic slurry composition>
Ceramic powder (barium titanate) 100 parts Binder (polyvinyl butyral resin) 5 parts Plasticizer (dioctyl phthalate) 1 part Toluene / MEK mixed solvent (1: 1 mixing ratio) 10 parts <Slurry coating property Criteria >
A: Extremely good coating property of slurry O: Good coating property of slurry Δ: Repelling of minute slurry is observed X: Repelling slurry A, ○ is a level that is not problematic in practical use.
[0015]
(3) Evaluation of the blocking property of the release film The film was cut into 10 cm square, 10 sheets were stacked so that the A side and the B side were combined, and pressed at 100 ° C. for 1 hour under the conditions of 10 kg / cm ² . The degree of occurrence of blocking during peeling was determined according to the following criteria.
<Criteria>
(Double-circle): Generation | occurrence | production of blocking is not recognized at all.
○: Almost no blocking occurred.
Δ: Generation of blocking is observed.
X: Generation | occurrence | production of blocking is recognized notably.
“◎”, “◯”, and “Δ” are levels that have no practical problem.
[0016]
(4) Peeling force [mN / cm]
Adhesive tape “No. 502” (manufactured by Nitto Denko Co., Ltd.) is applied to the surface of the release layer, left at room temperature for 1 hour, and then peeled 180 ° at a tensile speed of 300 mm / min with a tensile tester. The value obtained by dividing the average peeling load in the region where the peeling was stable by the width of the adhesive tape was defined as the peeling force.
[0017]
The manufacturing method of the film used in the Example and the comparative example is as follows.
(Manufacture of polyester)
86 parts of terephthalic acid and 70 parts of ethylene glycol were placed in a reactor and subjected to esterification at about 250 ° C. for 4 hours. Next, 0.012 part of germanium dioxide and 0.01 part of phosphoric acid (32 ppm as phosphorus element with respect to the polymer) were added, the temperature was gradually raised from 250 ° C. to 285 ° C., and the pressure was gradually reduced to 0.5 mmHg. It was. After 4 hours, the polymerization reaction was stopped to obtain polyethylene terephthalate (referred to as polyester A) having an intrinsic viscosity of 0.68. The respective element amounts of Ge and P remaining in the obtained polyester were 45 ppm and 25 ppm with respect to the polymer, respectively.
Polyester B was prepared by adding 20000 ppm of calcium carbonate having an average particle size of 0.7 μm during the production of polyester A.
Polyester C was prepared by adding 20000 ppm of amorphous silica having an average particle size of 2.4 μm during the production of polyester A.
Polyester D was prepared by adding 20000 ppm of aluminum oxide having an average particle size of 0.2 μm during the production of polyester A.
[0018]
(Manufacture of polyester film)
Polyethylene terephthalate with various mixing ratios is melted in one to three bent type twin screw extruders, co-extruded from a T-die onto a cast drum, rapidly cooled to below the glass transition point, and substantially amorphous multilayer A sheet was obtained. However, when casting, the co-extrusion stratigraphy was determined so that the side to be the A side was installed on the cast drum. The obtained amorphous sheet was stretched 3 times in the longitudinal direction at 90 ° C. with a roll stretching machine, and further stretched 4 times in the transverse direction at 100 ° C. with a tenter stretching machine. Subsequently, the film was heat-set at 230 ° C. for 10 seconds while maintaining the constant width, and further relaxed by 5% in the width direction at 180 ° C. to obtain a polyester film having a thickness of 50 μm.
[0019]
(Manufacture of release film)
The coating solution shown in Table 1 below, which was obtained by appropriately dissolving and diluting to a 2% concentration, was applied on a polyester film with a Mayer bar so that the wet thickness was 12 μm, followed by heat treatment at 120 ° C. for 2 minutes, A release film was obtained.
[0020]
Examples 1-2 and Comparative Examples 1-2
Upon co-extrusion of the base polyester film, various polyesters were mixed in the blending ratios shown in Table 1 to each of the P layer (surface on the A side), Q layer (intermediate layer), and R layer (surface layer constituting the B surface). The layers were laminated, and the obtained biaxially oriented polyester film was coated with the coating agents listed in Table 1 to obtain a release film.
[0021]
[Table 1]

In the above table, RA80 is ashioresin RA-80 (manufactured by Ashio Sangyo Co., Ltd.), and RA95 is ashioresin RA-95H (manufactured by Ashio Sangyo Co., Ltd.).
[0022]
【The invention's effect】
The release film of the present invention is suitable as a process film for thin-layer green sheets, and its industrial value is very high.

Claims (1)

The center surface average roughness (SRa (A)) of the surface (A surface) composed of a release layer comprising a long-chain alkyl group-containing polymer is 20 nm or less, and the normal peel force is 150 mN / cm or less. A release film having a center surface average roughness SRa (B) of the film surface (B surface) of 10 to 50 nm.