1. A microporous polyolefin multilayer film
comprising an inner layer made of a resin mixture containing polypropylene of 50-90 wt % having a melting temperature of 160\xb0 C. or higher and polyethylene of 10-50 wt % having a melting temperature of 125\xb0 C. to 135\xb0 C. and a surface layer formed on both surfaces of the inner layer, made of a resin mixture containing polyethylene of 95% or more having a melting temperature of 125\xb0 C. or higher,
wherein a thickness of the film is 9-50 \u03bcm, a puncture strength is 0.15N\u03bcm or more, a permeability is 1.5\xd710\u22125 Darcy or more, a multiplication of the puncture strength and the permeability is 0.4\xd710\u22125 Darcy\xb7N\u03bcm or more, a shrinkage in a transverse direction at 120\xb0 C. for 1 hour is 15% or less, and a melt fracture temperature of 160\xb0 C. or higher.
2. A microporous polyolefin multilayer film according to claim 1, wherein the thickness of the film is 9-30 \u03bcm, the puncture strength is 0.2N\u03bcm or more, the permeability is 2.5\xd710\u22125 to 12.0\xd710\u22125 Darcy, and the shrinkage in a transverse direction at 120\xb0 C. for 1 hour is 10% or less.
3. A microporous polyolefin multilayer film prepared by the method according to claim 1, wherein a surface layer is made of polyethylene having a melting temperature of 125\xb0 C. or higher, and
wherein the thickness of the film is 9-30 \u03bcm, the puncture strength is 0.2N\u03bcm or more, the permeability is 2.5\xd710\u22125 to 12.0\xd710\u22125 Darcy, and the shrinkage in a transverse direction at 120\xb0 C. for 1 hour is 10% or less.
4. A microporous polyolefin multilayer film prepared by the method according to claim 1, wherein a sum of each thickness of the surface layers is 50% or more of an total thickness, and a thickness of the inner layer is or more, and
wherein the thickness of the film is 9-30 \u03bcm, the puncture strength is 0.2 N\u03bcm or more the permeability is 2.5\xd710\u22125 to 12.0\xd710\u22125 Darcy, and the shrinkage in a transverse direction at 120\xb0 C. for 1 hour is 10% or less.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for treating coal to increase its rank, comprising:
subjecting the coal to a preliminary drying step to remove surface moisture;
raising the temperature of the coal to 400-750\xb0 F. for about 2-4 minutes;
heating the coal in a non-oxidizing atmosphere to remove substantially all moisture and a predetermined amount of from 5 to 95% of volatile matter from the coal while maintaining a majority of the coal’s natural structural form and integrity, wherein said non-oxidizing atmosphere is comprised of steam and volatiles removed during heating.
2. A process according to claim 1, wherein said coal is selected from peat, lignite, sub-bituminous coal, bituminous coal and anthracite coal.
3. A process according to claim 2, wherein the treated coal has a BTU content of 12,500 BTUlb. or higher.
4. A process according to claim 2, wherein the moisture content of the coal is reduced to about 2% by weight of the treated coal.
5. A process according to claim 2, wherein the volatile content of the treated coal is reduced to a predetermined volatile content percentage of between 5 and 30% by weight.
6. A process according to claim 2, wherein prior to heating the coal is subject to crushing to reduce the average size of the coal to 1-2 inches.
7. A process according to claim 6, wherein the preliminary drying step is carried out prior to crushing to reduce the surface moisture content.
8. A process according to claim 7, wherein the surface moisture content is reduced to about 2-4% by weight.
9. A process according to claim 6, wherein the crushed coal is subjected to a drying step by heating to a temperature in the range of 200-250\xb0 F. for a period of about 5 minutes in order to remove the surface moisture.
10. A process according to claim 9, wherein the surface moisture content is reduced to about 1-2% by weight.
11. A process according to claim 1, wherein the temperature of the coal is elevated to about 900-1100\xb0 F. for a period of about 1-4 minutes to produce coal with an inherent moisture content of less than 5% and a mass content loss of up to 50% by weight.
12. A process according to claim 11, wherein the temperature of the coal is raised to 1300-1550\xb0 F. and retained at that temperature for about 2-4 minutes to produce coal with a moisture content of 1-2% and a volatile content of 15-25%.
13. A process according to claim 12, wherein the temperature of he coal is raised to 2000-2400\xb0 F. to produce coal with a moisture content of 0-2% and a volatiles content of 5-15%.
14. A process according to claim 13, wherein the coal is cooled by exposing the coal to a dry cooling gas.
15. A process according to claim 14, wherein the cooling gas is substantially free of oxygen.
16. A process according to claim 15, wherein the cooling gas has a moisture content of less than 1% by weight.
17. A process according to claim 2, wherein said steam and volatiles removed during heating of the coal are recycled to provide a non-oxidizing atmosphere and to prevent ignition of the coal during heating.
18. A process according to claim 2 wherein said non-oxidizing atmosphere comprises nitrogen.