Ultrahigh molecular weight polyethylene stretched porous film

Patent metadata

Field	Value
Publication number	US-10340492-B2
Application number	US-201515128772-A
Country	US
Kind code	B2
Filing date	Mar 18, 2015
Priority date	Mar 26, 2014
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

An ultrahigh molecular weight polyethylene stretched microporous film, which comprises at least an ultrahigh molecular weight polyethylene having an intrinsic viscosity ([η]) of at least 7 dl/g and at most 60 dl/g, and which has a porosity of at least 10% and at most 70% and a breaking stress of at least 1 MPa when melt-stretched at 150° C., which uses, as the ultrahigh molecular weight polyethylene, preferably ultrahigh molecular weight polyethylene particles which satisfy (1) an intrinsic viscosity ([η]) of at least 7 dl/g and at most 60 dl/g, (2) a bulk density of at least 130 kg/m3 and at most 700 kg/m3, and (3) ΔTm (ΔTm=Tm1−Tm2) of at least 9° C. and at most 30° C., which is a difference between the melting point (Tm1) at the 1st scanning and the melting point (Tm2) at the 2nd scanning measured by DSC.

First claim

The invention claimed is:

1. An ultrahigh molecular weight polyethylene stretched microporous film, which comprises at least an ultrahigh molecular weight polyethylene having an intrinsic viscosity ([η]) of at least 7 dl/g and at most 60 dl/g, and which has a porosity of at least 10% and at most 70% and a breaking stress of at least 1 MPa when melt-stretched at 150° C.

2. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 1 , wherein ΔH >135 /ΔH whole is at least 40%, where ΔH whole is a total heat of fusion and ΔH >135 is a heat of fusion at 135° C. or higher, and ΔH >135 and ΔH whole are measured as endothermic peaks due to fusion by a differential scanning calorimeter (DSC) at a time when heated from 0° C. to 230° C. at a temperature-raising rate of 10° C./min.

3. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 1 , which is obtained by mixing ultrahigh molecular weight polyethylene particles and an organic solvent at a temperature of at least 50° C. and at most 300° C. to form a sheet-shaped product, subjecting the sheet-shaped product to biaxial stretching at a draw ratio of at least 2 times×2 times, and removing the organic solvent, wherein the ultrahigh molecular weight polyethylene particles satisfy at least the following conditions (1) to (3):
(1) an intrinsic viscosity ([η]) of at least 7 dl/g and at most 60 dl/g;
(2) a bulk density of at least 130 kg/m 3 and at most 700 kg/m 3 ; and
(3) a difference (ΔTm=Tm 1 -Tm 2 ) between Tm 1 and Tm 2 of at least 9° C. and at most 30° C., where Tm 1 is a melting point at a 1st scanning at a time when heated from 0° C. to 230° C. at a temperature-raising rate of 10° C./min by differential scanning calorimeter (DSC), and Tm 2 is a melting point at a 2nd scanning at a time when left to stand for 5 minutes after the 1st scanning, cooled to −20° C. at a temperature-decreasing rate of 10° C./min, left to stand for 5 minutes, and then heated from −20° C. to 230° C. at a temperature-raising rate of 10° C./min.

4. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 1 , which comprises an ultrahigh molecular weight polyethylene composition containing at least an ultrahigh molecular weight polyethylene having an intrinsic viscosity ([η]) of at least 7 dl/g and at most 60 dl/g and a polyethylene having a weight average molecular weight of at most 800,000.

5. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 4 , ΔH >135 /ΔH whole is at least 40% and at most 80% and ΔH whole is at least 190 J/g, where ΔH whole is the total heat of fusion and ΔH >135 is the heat of fusion at 135° C. or higher, and ΔH >135 and ΔH whole are measured as endothermic peaks due to fusion by a differential scanning calorimeter (DSC) at a time when heated from 0° C. to 230° C. at a temperature-raising rate of 10° C./min.

6. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 4 , wherein, when heated from 0° C. to 230° C. at a temperature-raising rate of 10° C./min by DSC, within ranges of at most 134° C. and at least 140° C., there is a temperature at which the maximum endothermic heat flux (W/g) within said temperature ranges is at least 60% of the maximum heat flux (W/g) in the total fusion peaks.

7. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 1 , which has a tensile break strength measured at 23° C. of at least 150 MPa and a heat shrinkage of at most 2%.

8. The ultrahigh molecular weight polyethylene stretched microporous film according to claim 1 , which is at least one member selected from the group consisting of a gas separation membrane, a semipermeable membrane, a tape, a tube and a battery separator.

Assignees

• Tosoh Corp

Inventors

• Inatomi Kei
• Wakabayashi Yasutake
• Abe Shigehiko

Classifications

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M10/0561

  the electrolyte being constituted of inorganic materials only · CPC title

• H01M10/0568

  characterised by the solutes · CPC title