RELEASE FILM

PROBLEM TO BE SOLVED: To provide a release film which has a comparatively heavy peeling force and a stable peeling force.SOLUTION: There is provided a release film having a release layer laminated on at least one surface of a biaxially stretched polyester film, where the release layer is formed of an addition polymerization type silicone resin made of methyl hydrogen polysiloxane and methyl alkenyl polysiloxane, and a heavy peeling agent, where a peeling force after an adhesive tape has been stuck onto the release layer is 100 mN/50 mm or more, a heating heavy peeling rate represented by formula (1): heating heavy peeling rate (%)={(Hb-Ha)/Ha}×100 is less than 30%, and haze reduction represented by formula (2): haze reduction=Hzb-Hza is 1% or less. In formula (1), Ha is an adhesive tape peeling force (mN/50 mm) in a state where the adhesive tape is stuck onto the release layer, and is left at room temperature for 24 hours; and Hb is an adhesive tape peeling force (mN/50 mm) in a state where the adhesive tape is stuck onto the release layer, is heated at 70°C for 24 hours, and is radiated to room temperature. In formula (2), Hza is a haze (%) of the release film after having wiped off with a cotton cloth impregnated with ethanol; and Hzb is a haze (%) of the release film before wiped off.SELECTED DRAWING: None 【課題】比較的に重い剥離力であり、また安定した剥離力の離型フィルムを提供する。【解決手段】二軸延伸ポリエステルフィルムの少なくとも片面に離型層が積層された離型フィルムであって、離型層がメチル水素化ポリシロキサンとメチルアルケニルポリシロキサンからなる付加重合型シリコーン樹脂及び重剥離化剤とからなり、離型層に粘着テープ貼り合わせ後の剥離力が１００ｍＮ／５０ｍｍ以上であり、下記（１）式で示される加熱重剥離化率が３０％未満であり、下記（２）式で示されるヘイズ減少が１％以下である離型フィルム。加熱重剥離化率（％）＝｛（Ｈｂ−Ｈａ）／Ｈａ｝×１００ （１）Ｈａ：粘着テープ貼り合わせ後、室温で２４時間放置後の粘着テープ剥離力（ｍＮ／５０ｍｍ）。Ｈｂ：粘着テープ貼り合わせ後、７０℃２４時間加熱し、室温にまで放熱した状態における粘着テープ剥離力（ｍＮ／５０ｍｍ）。ヘイズ減少（％）＝Ｈｚｂ−Ｈｚａ （２）Ｈｚａ：エタノールを浸み込ませた綿布で拭き取った後の離型フィルムのヘイズ（％）Ｈｚｂ：拭き取り前の離型フィルムのヘイズ（％）【選択図】なし