Microporous polypropylene film and process for producing the same
AssigneeToray Industries, Inc.
InventorsJun'ichi Masuda, Masatoshi Ohkura, Shigeru Tanaka, Reiko Morita, Hajime Fukushima
Life of this patent
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Abstract
A microporous polypropylene film where film formability is improved in accordance with a β-crystal technique which allows microporous films to be continuously manufactured at low cost is disclosed. In addition, a microporous polypropylene film of which the specific gravity is further reduced is provided. Furthermore, a microporous polypropylene film with a significantly high permeability is provided. In addition, manufacturing methods for these microporous polypropylene films are provided.
Claims16
A microporous polypropylene film comprising a polypropylene, said polypropylene having the Trouton ratio of not less than 30, said film having a β-crystal activity and a specific gravity of 0.1 to 0.6.
A microporous polypropylene film having the Trouton ratio of not less than 6, a β-crystal activity and a specific gravity of 0.1 to 0.6.
A microporous polypropylene film comprising a polypropylene, said polypropylene having a long chain branch in a main chain, said film having a β-crystal activity and a specific gravity of 0.1 to 0.6.
A manufacturing method for a microporous polypropylene film which comprises the steps of:
- melt-extruding a resin composition, a main component of said resin composition being a polypropylene with a β-crystal activity, said the polypropylene comprising a polypropylene with a Trouton ratio of not less than 30;
- casting the sheet onto a drum to obtain an unstretched sheet;
- and
- stretching the obtained sheet biaxially in longitudinal and transverse direction with a longitudinal stretching ratio of 5 to 10.
A manufacturing method for a microporous polypropylene film which comprises the steps of:
- melt-extruding a resin composition, a main component of said resin composition being a polypropylene;
- casting the resin composition onto a drum to obtain an unstretched sheet, said sheet having the Trouton ratio of not less than 6 and a β-crystal activity;
- and
- stretching the sheet biaxially in longitudinal and transverse direction with a longitudinal stretching ratio of 5 to 10.
A manufacturing method for a microporous polypropylene film comprising the steps of:
- melt-extruding a resin composition, a main component of said resin composition being a polypropylene with a β-crystal activity, said the polypropylene comprising a polypropylene having a long chain branch in a main chain;
- casting the sheet onto a drum to obtain an unstretched sheet;
- and
- stretching the obtained sheet biaxially in longitudinal and transverse direction with a longitudinal stretching ratio of 5 to 10.
A microporous polypropylene film comprising a polypropylene, wherein the relationship between the melt strength (MS) and the melt flow rate (MFR), measured at 230° C., of the polypropylene is represented by the following formula (1), said film having a β-crystal activity and a porosity of 30% to 95%.
- log(MS)>−0.61 log(MFR)+0.82 (1)
A microporous polypropylene film, wherein the melt strength (MS) of the film is less than 5 cN measured at 230° C., and a relationship between the MS and the melt flow rate (MFR) of the film is represented by the following formula (2), and said film having a β-crystal activity and a porosity of 30% to 95%.
- log(MS)>−0.9 log(MFR)+0.6 (2)
A manufacturing method for a microporous polypropylene film comprising the steps of:
- melt-extruding a resin composition into a sheet, said the resin composition comprises a polypropylene having a β-crystal activity as a main component, said polypropylene comprises a polypropylene having a relationship between the melt strength (MS) and the melt flow rate (MFR) of the polypropylene, measured at 230° C., represented by the following formula (1);
- casting the sheet onto a drum to obtain an unstretched sheet;
- and
- stretching the obtained sheet biaxially in longitudinal and transverse direction with a longitudinal stretching ratio of 5 to 10.
- log(MS)>−0.61 log(MFR)+0.82 (1)
A manufacturing method for a microporous polypropylene film comprising the steps of:
- melt-extruding a resin composition into a sheet, said the resin composition comprises a polypropylene having a β-crystal activity as a main component, wherein the melt strength (MS), measured at 230° C., of the polypropylene is less than 5 cN, and the polypropylene has a relationship between the MS and the melt flow rate (MFR) represented by the following formula (2);
- and
- casting the sheet onto a drum to obtain an unstretched sheet;
- and
- stretching the obtained sheet biaxially in longitudinal and transverse direction with a longitudinal stretching ratio of 5 to 10.
- log(MS)>−0.9 log(MFR)+0.6 (2)
A microporous polypropylene film, wherein the following formula (3) is satisfied in the in-plane intensity distribution profile scanned in the direction of an azimuthal angle for (−113) plane of the film in accordance with X-ray diffraction method, said film has a β-crystal activity and a specific gravity of 0.1 to 0.6.
- 0.5≦(MD)/I(TD)≦8 (3)
- (where, I (MD) is the integral intensity in the longitudinal direction and I (TD) is the integral intensity in the transverse direction.)
Dependencies are inferred from the claim text.