Method of making spunbonded webs from linear low density polyethylene

Claim 2

In the method of forming a spunbonded nonwoven web of continuous polyolefin filaments by extruding the polyolefin at a temperature above its melting point through a spinneret to form filaments of the polyolefin, drawing the filaments with an air gun, and depositing the filaments on a web-forming surface to form the nonwoven web, the improvement wherein the polyolefin is a linear copolymer of ethylene and an ethylenically unsaturated alpha-olefin having 4 to 8 carbon atoms, the copolymer having a percent crystallinity of at least 33 percent, a cone die melt flow of between about 65 and 85 grams/ten minutes, and a ratio of the natural logarithm of die swell to melt index of between about 0.014 and 0.020, and wherein the copolymer is extruded at a temperature between about 185° and 215° C.

Claim 3

The improvement of claim 1 wherein the copolymer has a degree of cystallinity between about 43 and 58 percent.

Claim 4

The improvement of claim 1 wherein the percent crystallinity is determined by measuring the enthalpy of fusion.

Claim 5

The improvement of claim 3 wherein the enthalpy of fusion is between about 30 and 40 calories per gram.

Claim 6

The improvement of claim 1 wherein the copolymer has a melt index between about 25 and 40 grams/ten minutes.

Claim 7

The improvement of claim 1 wherein the copolymer has a melt index between about 30 and 36 grams/ten minutes.

Claim 8

The improvement of claim 1 wherein the copolymer has a die swell between about 1.60 and 1.85.

Claim 9

The improvement of claim 1 wherein the copolymer has a density less than about 0.955.

Claim 10

The improvement of claim 1 wherein the copolymer has a die swell between about 1.50 and 1.95.

Claim 11

The improvement of claim 9 wherein the copolymer has a peak width of less than about 25 degrees.

Claim 12

In the method of forming a spunbonded nonwoven web of continuous polyolefin filaments by extruding the polyolefin at a temperature above its melting point through a spinneret to form filaments of the polyolefin, drawing the filaments with an air gun, and depositing the filaments on a web-forming surface to form the nonwoven web, the improvement wherein the polyolefin is a linear copolymer of ethylene and an ethylenically unsaturated alpha-olefin having 4 to 8 carbon atoms, the copolymer having a percent crystallinity as determined from enthalpy of fusion of between about 43 and 58 percent, a cone die melt flow between about 65 and 85 grams/ten minutes, a die swell between about 1.50 and 1.95, a melt index between 25 and 40grams/ten minutes, a ratio of the natural logarithm of the die swell to the melt index between about 0.014 and 0.020, a peak width of less than about 25 degrees, and wherein the copolymer is extruded at a temperature between about 185° and 215° C.

Claim 13

In the method of forming a spunbonded nonwoven web of continuous polyolefin filaments by extruding the polyolefin at a temperature above its melting point through a spinneret to form filaments of the polyolefin, drawing the filaments with an air gun, and depositing the filaments on a web-forming surface to form the nonwoven web, the improvement wherein the polyolefin is a linear copolymer of ethylene and an ethylenically unsaturated alpha-olefin having 4 to 8 carbon atoms, the copolymer having a percent crystallinity as determined from enthalpy of fusion of between about 43 and 58 percent, a cone die melt flow between about 65 and 85 grams/ten minutes, a die swell between about 1.50 and 1.95, a melt index between 25 and 40grams/ten minutes, a ratio of the natural logarithm of the die swell to the melt index between about 0.014 and 0.020, a peak width of less than about 25 degrees, and wherein the copolymer is extruded at a temperature between about 185° and 215° C.