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US 11,961,683 B2Granted
Biaxially stretched polypropylene film, metallized film, metallized film roll and film capacitor
AssigneeOji Holdings Corporation
InventorsYoshimune Okuyama, Takeshi Tominaga, Yoshikazu Fujishiro, Tadakazu Ishiwata
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Abstract
A biaxially stretched polypropylene film which has a thickness of from 1.0 μm to 3.5 μm, a tensile fracture stress at 135° C. of 70 MPa or more in a first direction, and a difference between the tensile fracture stress at 125° C. in the first direction and the tensile fracture stress at 135° C. in the first direction of from 0 MPa to 15 MPa (inclusive).
Claims16
A biaxially stretched polypropylene film produced by:
- obtaining a cast roll stock sheet produced by melting and extruding a resin;
- preheating the cast roll stock sheet using a machine direction (MD) preheating roll group, wherein temperature of the MD preheating roll group during a first stage in said preheating is set to 60-95° C., temperature of the MD preheating roll group during a second stage in said preheating is set to 115-138° C., and contact time with the MD preheating roll group during the second stage of said preheating is set to 5-10 seconds;
- stretching the cast roll stock sheet in the MD direction using a MD stretching roll group, wherein a MD stretching ratio is set to 4.5-5.5 times, and temperature of the MD stretching roll group is set to 130-150° C., contact time with the MD stretching roll group is set to 1-2 seconds during said stretching;
- and
- relaxing the cast roll stock sheet using a MD relaxing roll group, wherein temperature of the MD relaxing roll group is set to 120-128° C. and contact time with the MD relaxing roll group is set to 1-2 seconds during said relaxing,
- wherein the biaxially stretched polypropylene film has:
- a thickness of from 1.0 μm to 3.5 μm;
- a tensile fracture stress of 70 MPa or more at 135° C. in a first direction;
- and
- a difference between a tensile fracture stress at 125° C. in the first direction and a tensile fracture stress at 135° C. in the first direction of 0 MPa or more and 15 Mpa or less.
7 more elements
A method of producing a biaxially stretched polypropylene film, comprising:
- obtaining a cast roll stock sheet produced by melting and extruding a resin:
- preheating the cast roll stock sheet using a machine direction (MD) preheating roll group, wherein temperature of the MD preheating roll group during a first stage in said preheating is set to 60-95° C., temperature of the MD preheating roll group during a second stage in said preheating is set to 115-138° C., and contact time with the MD preheating roll group during the second stage of said preheating is set to 5-10 seconds:
- stretching the cast roll stock sheet in the MD direction using a MD stretching roll group, wherein a MD stretching ratio is set to 4.5-5.5 times, and temperature of the MD stretching roll group is set to 130-150° C., contact time with the MD stretching roll group is set to 1-2 seconds during said stretching;
- relaxing the cast roll stock sheet using a MD relaxing roll group, wherein temperature of the MD relaxing roll group is set to 120-128° C. and contact time with the MD relaxing roll group is set to 1-2 seconds during said relaxing,
- wherein the biaxially stretched polypropylene film has a tensile fracture stress of 70 MPa or more at 135° C. in a first direction,
- wherein a difference between a tensile fracture stress at 125° C. in the first direction of the biaxially stretched polypropylene film and a tensile fracture stress at 135° C. in the first direction of the biaxially stretched polypropylene film is 0-15 MPa.
3 more elements
Dependencies are inferred from the claim text.