PRODUCTION METHOD OF MICROPOROUS PLASTIC FILM
A method of producing a microporous plastic film is disclosed. The method achieves various characteristics such as strength while having an excellent appearance grade by using a wet stretching method. The method includes kneading a diluent and a polymer with an extruder to produce a kneaded polymer, discharging the kneaded polymer into a sheet, and stretching the sheet in a conveying direction of the sheet with a plurality of rollers. The diluent is applied to at least one of the rollers and the sheet while stretching the sheet.
1 . A method of producing a microporous plastic film, the method comprising:
kneading a diluent and a polymer with an extruder to produce a kneaded polymer;
discharging the kneaded polymer into a sheet; and
stretching the sheet in a conveying direction of the sheet with a plurality of rollers; wherein, while stretching the sheet, an amount of the diluent on the sheet is not less than 4×10 −3 L/m 2 and not greater than 40×10 −3 L/m 2 .
2 . A method of producing a microporous plastic film, the method comprising:
kneading a diluent and a polymer with an extruder to produce a kneaded polymer;
discharging the kneaded polymer into a sheet; and
stretching the sheet in a conveying direction of the sheet with a plurality of rollers; wherein, while stretching the sheet, the diluent is applied to at least one of the plurality of rollers and the sheet.
3 . The method according to claim 2 , wherein an application rate of the diluent is not less than 5×10 −3 L/m 2 and not greater than 30×10 −3 L/m 2 .
4 . The method of claim 1 , wherein, while stretching, the sheet is pressed between a heating roller a nip roller having a rubber surface.
5 . The method of claim 2 , wherein, while stretching, the sheet is pressed between a heating roller and a nip roller having a rubber surface.
6 . The method of claim 3 , wherein, while stretching, the sheet is pressed between a heating roller and a nip roller having a rubber surface.
7 . A device for producing a microporous film, the device comprising:
an extruder configured to knead a diluent and a polymer to form a kneaded polymer;
an opening configured to discharge the kneaded polymer into a sheet; and
a longitudinal stretching unit having a plurality of rollers configured to stretch the sheet in a conveying direction of the sheet, wherein an amount of the diluent is not less than 4×10 −3 L/m 2 and not greater than 40×10 −3 L/m 2 in the longitudinal stretching unit.
8 . A device for producing a microporous film, the device comprising:
an extruder configured to knead a diluent and a polymer to form a kneaded polymer;
an opening configured to discharge the kneaded polymer into a sheet; and
a longitudinal stretching unit having a plurality of rollers configured to stretch the sheet in a conveying direction of the sheet; and
a diluent application device configured to apply a diluent to at least one of the plurality of rollers of the longitudinal stretching unit and the sheet while in the longitudinal stretching unit.
9 . The device according to claim 8 , wherein an application rate of the diluent is not less than 5×10 −3 L/m 2 and not greater than 30×10 −3 L/m 2 .
10 . The device according to claim 7 , further comprising a heating roller for heating the sheet and a nip roller configured to press the sheet between the nip roller and the heating roller, wherein the nip roller has a rubber surface.
11 . The device according to claim 8 , further comprising a heating roller for heating the sheet and a nip roller configured to press the sheet between the nip roller and the heating roller, wherein the nip roller has a rubber surface.
12 . The device according to claim 9 , further comprising a heating roller for heating the sheet and a nip roller configured to press the sheet between the nip roller and the heating roller, wherein the nip roller has a rubber surface.