JP-7856008-B2 - Method for manufacturing release film for resin sheet molding

JP7856008B2JP 7856008 B2JP7856008 B2JP 7856008B2JP-7856008-B2

Inventors

重野健斗
柴田悠介
楠葉浩晃
中谷充晴

Assignees

東洋紡株式会社

Dates

Publication Date: 20260511
Application Date: 20211217
Priority Date: 20201223

Claims (6)

A method for manufacturing a release film for resin sheet molding , comprising a base material and a release layer , The above manufacturing method comprises the following steps: A coating step in which a release layer forming composition is applied to the surface layer A of a polyester film having a surface layer A, The aforementioned surface layer A is a layer that does not substantially contain inorganic particles. The release layer forming composition comprises a cationic curable polydimethylsiloxane (a), Coating process; A drying step in which the polyester film coated with the release layer forming composition is heat-dried, The aforementioned heating and drying process comprises a first drying step and a second drying step. A drying step in which the drying temperature T1 in the first drying step is higher than the drying temperature T2 in the second drying step; The drying step is followed by a photocuring step in which the release layer forming composition is cured by irradiating it with active energy rays; A method for producing a release film for resin sheet molding, wherein the content of cationic curable polydimethylsiloxane (a) in the release layer is 90 mg/m² or less.
The aforementioned release layer forming composition contains an organic solvent with an SP value (δ) of 14 or more and 17 or less. The aforementioned release layer forming composition contains an organic solvent with an SP value (δ) of 14 or more and 17 or less in an amount of 10% by mass or more per 100 parts by mass of the total weight of the release layer forming composition. In the coating step, the amount of the release layer forming composition applied is 10 g/ m² or less. A method for manufacturing a release film for resin sheet molding according to claim 1.
A method for producing a release film for manufacturing a resin sheet containing an inorganic compound, A method for producing a release film for resin sheet molding according to claim 1 or 2, wherein the content of cationic curable polydimethylsiloxane (a) in the release layer is 50 mg/m² or less.
The method for producing a release film for molding a resin sheet according to claim 3, wherein the resin sheet containing an inorganic compound is a ceramic green sheet.
A method for manufacturing a release film for resin sheet molding according to claim 4, further comprising forming a ceramic green sheet with a thickness of 0.2 μm or more and 1.0 μm or less, wherein the method is for manufacturing a ceramic green sheet.
A method for producing a release film for molding resin sheets according to claim 3 or 4, comprising molding a resin sheet having a thickness of 0.2 μm or more and 1.0 μm or less.

Description

The present invention relates to a method for manufacturing a release film for molding resin sheets, and more specifically, to a method for manufacturing a release film used when molding an ultra-thin resin sheet. Conventionally, release films, which use a polyester film as a base material and laminate a release layer on top of it, have been used as process films for molding resin sheets such as adhesive sheets, cover films, polymer films, and optical lenses. The aforementioned release film is also used as a process film for molding ceramic green sheets, which require high smoothness for multilayer ceramic capacitors, ceramic substrates, and other applications. In recent years, with the miniaturization and increase in capacitance of multilayer ceramic capacitors, there has been a trend towards thinner ceramic green sheets. Ceramic green sheets are molded by coating a slurry containing ceramic components such as barium titanate and a binder resin onto a release film and drying it. Multilayer ceramic capacitors are manufactured by printing electrodes onto the molded ceramic green sheet, peeling it off the release film, and then laminating, pressing, firing, and applying external electrodes to the resulting ceramic green sheet. When molding ceramic green sheets onto the surface of a polyester film substrate's release layer, a problem has arisen where minute protrusions on the release layer surface affect the molded ceramic green sheet, easily causing defects such as repellency and pinholes. In recent years, further thinning of ceramic green sheets has progressed, and there is a growing demand for ceramic green sheets with a thickness of 1.0 μm or less, more specifically 0.2 μm to 1.0 μm. Therefore, the requirements for smoothness of the release layer surface have increased even further. In addition, there has been a problem where extremely minute protrusions and foreign matter on the release layer can lead to deformation of the molded ceramic green sheet, making it easier for pinholes to occur and the sheet to crack during peeling. Furthermore, as ceramic green sheets become thinner, the release properties when peeling the ceramic green sheet from the release film become even more important. If the peeling force is strong and uneven, the ceramic green sheet will be damaged during the peeling process, resulting in sheet defects, uneven thickness, pinholes, sheet cracking, and other problems. Therefore, there is a need to peel the ceramic green sheet with a lower and more uniform force. In other words, in order to manufacture ultra-thin resin sheets, especially ceramic green sheets, without defects, a release film with extremely high smoothness and excellent peelability is required. Examples of release films with excellent smoothness and release properties include those described in the following patent documents. For example, Patent Document 1 proposes a release film having a release layer mainly composed of a radical-curing resin. Patent Document 2 proposes a release film having a structure in which a smoothing layer and a release layer are laminated. Patent Document 3 proposes a release film having a release layer mainly composed of a cationic-curing epoxy resin. Patent Document 4 proposes a release film having a release layer mainly composed of a cationic-curing polydimethylsiloxane. Patent No. 5492352Japanese Patent Publication No. 2015-164762International Publication No. 2018/079337Japanese Patent Publication No. 2016-079349 The present invention will be described in detail below. The present invention makes it possible to manufacture a release film having the following configuration. A release film for molding resin sheets, comprising a polyester film as a base material and a release layer, The polyester film has a surface layer A that is substantially free of inorganic particles, A release layer is provided on the surface layer A. The release layer is a layer formed by curing the release layer forming composition. The release layer forming composition contains a cationic curable polydimethylsiloxane (a), The surface roughness (Sa) of the release layer region is 2 nm or less. This is a release film for resin sheet molding, in which the number of protrusions with a height of 10 nm or more on the surface of the release layer is 200 or less per mm² . The release film manufactured by the present invention having such a configuration has excellent smoothness and peelability of the release layer, so for example, for a resin sheet with a thickness of 0.2 μm to 1.0 μm or less, It can provide a uniform thickness without defects and suppress flaws such as pinholes. Furthermore, the release film manufactured according to the present invention can provide the following effects. In this invention, since the release layer is provided on a base film with sufficient smoothness, the smoothness of the release layer can also be ensured. Moreover, in this invention, curing defects due to oxygen inhibition can be suppressed i