Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
66 words
A substantially skinless microporous polypropylene membrane characterized by having (a) a bubble point in the range of from 25 to 50 psi; (b) a thickness in the range of from 3 to 7 mils; (c) a nitrogen flow rate of at least 0.5 liters per square centimeter-minute; (d) a burst strength of at least 10 psi; and (e) an S value of about 15, or less.
Claim 2
Dependent Claim
66 words
A substantially skinless microporous polypropylene membrane characterized by having (a) a bubble point in the range of from 25 to 50 psi; (b) a thickness in the range of from 3 to 7 mils; (c) a nitrogen flow rate of at least 0.5 liters per square centimeter-minute; (d) a burst strength of at least 10 psi; and (e) an S value of about 15, or less.
Claim 3
Dependent Claim
20 words
A membrane as claimed in claim 1 which has a skin throughout no more than 10 percent of its cross-section.
Claim 4
Dependent Claim
23 words
A membrane as claimed in claim 1 or .claim 2 which has a thickness in the range of from 3.5 to 4.0 mils.
Claim 5
Dependent Claim
23 words
A membrane as claimed in any one of the preceding claims having a flow rate of at least 0.7 liters per square centimeter-minute.
Claim 6
Dependent Claim
43 words
A membrane as claimed in claim 4 having a skin throughout less than 5 percent of its cross-section, having a thickness in the range of from 3.5 to 4.0 mils, and having a sharpness value in the range of from 8 to 14.
Claim 7
Independent Claim
112 words
A method of preparing a substantially skinless microporous polypropylene membrane comprising heating a mixture of about 30 percent polypropylene and about 70 percent, N,N-bis(2-hydroxyethyl)tallowamine, by weight, to a temperature and for a time sufficient to form a homogeneous solution, castingor extruding the solution at a thickness in the range of from 3 to 7 mils, onto a chill roll maintained at a temperature in the range of from 50 to 80°C, allowing the solution to solidify on the chill roll to form a solid sheet, removing the solid sheet from the chill roll and removing at least a substantial portion of the liquid from the sheet to form the microporous polypropylene membrane.
Claim 8
Independent Claim
112 words
A method of preparing a substantially skinless microporous polypropylene membrane comprising heating a mixture of about 30 percent polypropylene and about 70 percent, N,N-bis(2-hydroxyethyl)tallowamine, by weight, to a temperature and for a time sufficient to form a homogeneous solution, castingor extruding the solution at a thickness in the range of from 3 to 7 mils, onto a chill roll maintained at a temperature in the range of from 50 to 80°C, allowing the solution to solidify on the chill roll to form a solid sheet, removing the solid sheet from the chill roll and removing at least a substantial portion of the liquid from the sheet to form the microporous polypropylene membrane.
Claim 9
Dependent Claim
21 words
A method as claimed in claim 6 wherein the solution is cast at a thickness of from 3.5 to 4 mils.
Claim 10
Dependent Claim
18 words
A method as claimed in claim 6 or claim 7 wherein the chill roll temperature is about 60°C.
Claim 11
Independent Claim
19 words
A method as claimed in any one of claims 6 to 8 wherein the liquid is removed with isopropanol..
Claim 12
Independent Claim
40 words
A method as claimed in any one of claims 6 to 9 wherein a wiper bar is used on the chill roll prior to the location at which the homogeneous solution is cast or : extruded onto the chill roll.