Aqueous-based polyurethane compositions and method of preparation

Claim 3

A method of claim 1 wherein said equivalent excess of water is at least a two-fold excess.

Claim 4

A method of claim 1 wherein said prepolymer comprises the reaction product of a hydrophilic polyol and a polyisocyanate.

Claim 5

A method of claim 3 wherein said polyol is a polyoxyethylene polyol.

Claim 6

A method of claim 4 wherein said polyoxyethylene polyol is polyethylene glycol.

Claim 7

A method of claim 3 wherein said polyisocyanate is a diisocyanate.

Claim 8

A method of claim 1 wherein said monofunctional blocking agent is selected from the group consisting of alcohols, primary amines, secondary amines, oximes, and alkanol amines.

Claim 9

A method of claim 1 wherein said monofunctional blocking agent is less reactive with said prepolymer than water and an equivalent excess, based on the isocyanate content of said prepolymer, is used to control the rate of said chain extension.

Claim 10

A method of claim 8 wherein said monofunctional blocking agent is an alcohol.

Claim 11

A method of claim 9 wherein said alcohol is ethanol.

Claim 12

A method of claim 1 wherein said monofunctional blocking agent is more reactive with said prepolymer than water and less than an equivalent amount, based on the isocyanate content of said prepolymer, is added to control the rate of said chain extension.

Claim 13

A method of claim 11 wherein said blocking agent is an oxime.

Claim 14

A method of claim 1 wherein said additional monofunctional blocking agent or said second blocking agent is added in an equivalent excess based on the equivalents of said remaining unreacted isocyanate groups.

Claim 15

A method of claim 1 wherein said second isocyanate group blocking agent is selected from the group consisting of monofunctional and polyfunctional alcohols, primary amines, secondary amines, and oximes; alkanol amines; and ammonia.

Claim 16

A method of claim 14 wherein said second blocking agent comprises, in combination, a monofunctional alcohol and ammonia.

Claim 17

An aqueous based, cold seal, polyurethane adhesive solution prepared by a method comprising the steps of: providing a reaction mixture comprising an isocyanate-terminated urethane prepolymer and an equivalent excess of water, based on the isocyanate content of said prepolymer; reacting said prepolymer and said water to effect chain extension of said prepolymer; controlling the rate of said chain extension by adding to said reaction mixture a monofunctional isocyanate group blocking agent and permitting reaction between said agent and isocyanate groups in said prepolymer; permitting said prepolymer and said water to react until said reaction mixture acquires a desired adhesive capability; and adding to said reaction mixture additional said monofunctional isocyanate group blocking agent or a second isocyanate group blocking agent in an amount at least substantially equal to the remaining unreacted isocyanate groups in said prepolymer on an equivalent basis.

Claim 18

An aqueous based, cold seal, polyurethane adhesive solution prepared by a method comprising the steps of: providing a reaction mixture comprising an isocyanate-terminated urethane prepolymer and an equivalent excess of water, based on the isocyanate content of said prepolymer; reacting said prepolymer and said water to effect chain extension of said prepolymer; controlling the rate of said chain extension by adding to said reaction mixture a monofunctional isocyanate group blocking agent and permitting reaction between said agent and isocyanate groups in said prepolymer; permitting said prepolymer and said water to react until said reaction mixture acquires a desired adhesive capability; and adding to said reaction mixture additional said monofunctional isocyanate group blocking agent or a second isocyanate group blocking agent in an amount at least substantially equal to the remaining unreacted isocyanate groups in said prepolymer on an equivalent basis.

Claim 19

A composition of claim 16 wherein said equivalent excess of water is at least a two-fold excess.

Claim 20

A composition of claim 16 wherein said prepolymer comprises the reaction product of a hydrophilic polyoxyethylene polyol and a polyisocyanate.

Claim 21

A composition of claim 16 wherein said monofunctional blocking agent is selected from the group consisting of alcohols, primary amines, secondary amines, oximes, and alkanol amines.

Claim 22

A composition of claim 19 wherein said monofunctional blocking agent is an alcohol which is added in an equivalent excess, based on the isocyanate content of said prepolymer, to control the rate of said chain extension.

Claim 23

A composition of claim 16 wherein said additional monofunctional blocking agent or said second blocking agent is added in an equivalent excess, based on the equivalents of said remaining unreacted isocyanate groups.

Claim 24

A composition of claim 16 comprising, as a water-miscible cosolvent added prior to, during, or subsequent to reaction of said water and said prepolymer, methanol, ethanol, isopropanol, acetone, or methyl ethyl ketone.

Claim 25

A composition of claim 16 comprising a carrier solvent comprising at least 10% by weight of water.

Claim 28

A method of claim 24 further comprising coating said adhesive composition on a surface of said second substrate, drying the adhesive coating on said second substrate, and contacting the respective adhesive coatings on said first and second substrates.

Claim 29

A method of claim 24 wherein said first and second substrates are selected from the group consisting of paper, metal, polyurethane foam, synthetic polymer sheets, and synthetic polymer fibers.