Method for bonding fibrous web materials

Claim 3

The method according to claim 1 wherein said prepolymer is printed onto said fibrous web.

Claim 4

The method according to claim 2 wherein the weight of said prepolymer binder printed onto the fibrous web is from about 5 to about 30% of the weight of said fibrous web.

Claim 5

The method according to claim 3 wherein (a) the spacing between said rollers is adapted such that said rollers contact each other with minimal pressure.

Claim 6

The method according to claim 4 wherein (a) the temperature of said rollers is from about 120° C. to about 190° C., and (b) said fibrous web is fed through said rollers at a rate of from about 50 to about 150 m/min.

Claim 7

The method according to claim 3 wherein said prepolymer binder composition comprises a solution of said prepolymer and a thinner for said prepolymer.

Claim 8

The method according to claim 6 wherein said thinner is selected from the group consisting of tri- or tetrafunctional acrylate monomers or multifunctional acrylate oligomers.

Claim 9

The method according to claim 7 wherein said thinner is a multifunctional acrylate monomer selected from the group consisting of pentaerythrite triacrylate, pentaerythrite tetraacrylate, or trimethylolpropane triacrylate; and said prepolymer is selected from the group consisting of the low molecular weight polyurethane, polyester or polyepoxy prepolymers.

Claim 10

The method according to claim 3 wherein said prepolymer composition is heated.

Claim 11

The method according to claim 2 wherein said prepolymer binder is cured by exposing said fibrous web to a high-pressure mercury lamp having a radiation output of at least about 80 Watts per cm of fibrous web width.

Claim 12

The method according to claim 2 wherein the surface of said rollers is roughened.

Claim 13

The method according to claim 2 wherein said fibrous web is comprised of nylon fibers or polyacrylonitrile fibers.

Claim 14

The method according to claim 3 wherein the weight of said prepolymer is from about 10 to about 25 percent of the weight of said fibrous web, and said prepolymer binder composition has a viscosity of from about 1000 to about 4000 centipoise.

Claim 15

The method according to claim 3 wherein the viscosity of said prepolymer binder composition is adjusted by the addition of an oligomer to said prepolymer.

Claim 16

The method according to claim 3 wherein said prepolymer binder composition comprises a mixture of polyurethane prepolymer with polyurethane oligomer.

Claim 17

In a method for bonding a fibrous web by printing a prepolymer binder onto one or both surfaces of the fibrous web, and subsequently cross-linking said prepolymer binder, the improvement which comprises: (a) compressing, smoothing and heating said fibrous web immediately prior to printing a solvent-free prepolymer binder onto said web, wherein said fibrous web is passed through rollers heated to a temperature at least about 20° C. below the melting point of the fibers comprising said web, such that said web is compressed, smoothed and heated but the fibers of said web are not bonded together and wherein said prepolymer binder has a viscosity of from about 500 to 5000 centipoise, and is printed onto said fibrous web in an amount comprising from about 5 to about 30% of the weight of said fibrous web; and (b) subsequent to printing said prepolymer binder onto said fibrous web, immediately exposing said fibrous web to ultraviolet light to cure said prepolymer binder.

Claim 18

In a method for bonding a fibrous web by printing a prepolymer binder onto one or both surfaces of the fibrous web, and subsequently cross-linking said prepolymer binder, the improvement which comprises: (a) compressing, smoothing and heating said fibrous web immediately prior to printing a solvent-free prepolymer binder onto said web, wherein said fibrous web is passed through rollers heated to a temperature at least about 20° C. below the melting point of the fibers comprising said web, such that said web is compressed, smoothed and heated but the fibers of said web are not bonded together and wherein said prepolymer binder has a viscosity of from about 500 to 5000 centipoise, and is printed onto said fibrous web in an amount comprising from about 5 to about 30% of the weight of said fibrous web; and (b) subsequent to printing said prepolymer binder onto said fibrous web, immediately exposing said fibrous web to ultraviolet light to cure said prepolymer binder.

Claim 19

The method according to claim 16 wherein (a) said fibrous web is smoothed, compressed and heated by passing it through heated rollers; and (b) the spacing between said rollers is adapted such that said rollers contact each other with minimal pressure; and (c) the temperature of said rollers is adjusted to within the range of from about 120° to about 190° C., and at least about 20° C. below the melting point of the fibers of said web; and (d) said fibrous web is fed through said rollers at the rate of from about 50 to about 150 m/min.

Claim 21

The method according to claim 18 wherein said fibrous web having said prepolymer printed thereon is exposed to a high-pressure mercury lamp having an output of at least about 80 Watts per cm of width of said fibrous web.