Release film, method for manufacturing release film

Abstract

The present invention addresses the problem of providing a release film for producing a ceramic green sheet, the release film being capable of suppressing unevenness in the overall thickness of the ceramic green sheet during the production of the ceramic green sheet. The release film according to the present invention has a release layer, a polyester substrate, and a particle-containing layer in this order, wherein when the release film is heat-treated for 20 sec under a condition in which the temperature reaches 90°C, while the release film is conveyed under conditions in which the conveying speed is 30 m / min and the tensile force in the conveying direction is 100 N / m, the total area of streak-like defect regions observed in the release film is equal to or less than 40% of the total area of observed regions.

Claims

1. A release film having a release layer, a polyester substrate, and a particle-containing layer in this order, A release film in which, when the release film is heated for 20 seconds at a temperature of 90°C while being transported at a transport speed of 30 m / min and a tension of 100 N / m in the transport direction, the total area of ​​the streaky defect regions observed on the release film is 40% or less of the total area of ​​the observation region.

2. The release film according to claim 1, for use in manufacturing ceramic green sheets.

3. The release film according to claim 1 or 2, wherein the polyester substrate is substantially free of particles.

4. The surface free energy of the surface of the release layer opposite to the polyester substrate is 10 to 35 mJ / m ２ The release film according to claim 1 or 2.

5. The release film according to claim 1 or 2, wherein the thickness of the release layer is 30 to 200 nm.

6. The surface free energy of the particle-containing layer on the surface opposite to the polyester substrate is 25 to 45 mJ / m ２ The release film according to claim 1 or 2.

7. The release film according to claim 1 or 2, wherein the thickness of the release film is 40 μm or less.

8. A film manufacturing process for producing a polyester film having, in this order, a release layer, a biaxially oriented polyester substrate, and a particle-containing layer, The process includes a heat setting step in which the polyester film is heated and fixed at a temperature of less than 240°C, A heat relaxation step is performed in which the polyester film heat-fixed in the heat-fixing step is heated at a lower temperature than that of the heat-fixing step to relax it. A cooling step for cooling the polyester film that has been thermally relaxed by the aforementioned thermal relaxation step, A method for manufacturing a release film, comprising: an expansion step of expanding the heat-relaxed polyester film in the width direction during the cooling step to produce a release film, The cooling rate of the polyester film in the aforementioned cooling process is greater than 500°C / min and less than 4000°C / min. The film manufacturing process includes a first stretching step in which an unstretched polyester substrate is stretched in either the transport direction or the width direction to form a uniaxially oriented polyester substrate, and a second stretching step in which the uniaxially oriented polyester substrate is stretched in the other direction of the transport direction and the width direction to form a biaxially oriented polyester substrate, performed either in stages or simultaneously. A method for manufacturing a release film, wherein the film manufacturing step includes a release layer forming step, which is performed before the stretching step or between the first stretching step and the second stretching step, by applying a release layer forming composition onto the polyester substrate to form the release layer.

9. The film manufacturing process includes, prior to the stretching process, an extrusion molding process in which an unstretched polyester substrate is formed by extrusion molding, A method for producing a release film according to claim 8, comprising a particle-containing layer forming step between the extrusion molding step and the stretching step, or between the first stretching step and the second stretching step, in which a particle-containing layer forming composition is applied to the polyester substrate to form the particle-containing layer.

10. The method for producing a release film according to claim 8, wherein the film production step includes an extrusion molding step, prior to the stretching step, a step of forming an unstretched polyester substrate on which particle-containing layers are laminated by co-extrusion molding.

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