Polyurethane pressure-sensitive adhesives
First Claim
1. A pressure-sensitive adhesive comprising a polyurethane polymer formed by the reaction of an isocyanate component and a polyol component having a molecular weight between about 1,000 and 10,000, said components being reacted at a molar ratio of isocyanate moieties to hydroxyl moieties of less than one, said polymer being free from any added tackifying and plasticizing agents, said polymer having a glass transition temperature of less than about 0°
- C., a moisture absorption at equilibrium of at least 20% of its weight, and a peel adhesion to human skin of between about 0.3 and 4 newtons/cm width of the polymer, wherein said isocyanate and said polyol components each have a functionality of at least two and wherein at least one of said components has a functionality that is greater than 2, and further wherein said polyurethane polymer is crosslinked to a crosslink density α
of between about 10-4 and 10-3 wherein α
is defined by the equation ##EQU5## where i=1 to n where n is the number of the reactant components;
Xi =the mole fraction of the ith component;
Fi =the functionality of the ith component;
r=the NCO/OH ratio; and
Mw=the molecular weight of the polyol.
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Abstract
Pressure-sensitive adhesives which possess absorptivity and/or permeability properties to remove transepidermal water loss and/or other bodily fluids that come into contact with the adhesive, in combination with a fine balance of cohesion and adhesion properties, can be formulated by controlling the crosslinking of a polyurethane polymer having excess hydroxyl functionality, a glass transition temperature of less than about 0° C., a moisture absorption of at least about 20% of its weight and/or a moisture vapor transmission rate of at least about 300 grams/meter2 /24 hours measured at 37° C. and a 90% relative humidity gradient. Adhesives of these polymers possess a peel adhesion to human skin of between about 0.3 and 4 newtons/cm width of the polymer or adhesive.
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Citations
23 Claims
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1. A pressure-sensitive adhesive comprising a polyurethane polymer formed by the reaction of an isocyanate component and a polyol component having a molecular weight between about 1,000 and 10,000, said components being reacted at a molar ratio of isocyanate moieties to hydroxyl moieties of less than one, said polymer being free from any added tackifying and plasticizing agents, said polymer having a glass transition temperature of less than about 0°
- C., a moisture absorption at equilibrium of at least 20% of its weight, and a peel adhesion to human skin of between about 0.3 and 4 newtons/cm width of the polymer, wherein said isocyanate and said polyol components each have a functionality of at least two and wherein at least one of said components has a functionality that is greater than 2, and further wherein said polyurethane polymer is crosslinked to a crosslink density α
of between about 10-4 and 10-3 wherein α
is defined by the equation ##EQU5## where i=1 to n where n is the number of the reactant components;Xi =the mole fraction of the ith component; Fi =the functionality of the ith component; r=the NCO/OH ratio; and Mw=the molecular weight of the polyol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- C., a moisture absorption at equilibrium of at least 20% of its weight, and a peel adhesion to human skin of between about 0.3 and 4 newtons/cm width of the polymer, wherein said isocyanate and said polyol components each have a functionality of at least two and wherein at least one of said components has a functionality that is greater than 2, and further wherein said polyurethane polymer is crosslinked to a crosslink density α
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15. A method for making a pressure-sensitive adhesive for application to skin which comprises:
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providing a mixture of an isocyanate component, having a functionality of at least 2, and a polyol component having a molecular weight of between about 1,000 and 10,000 and also having a functionality of at least 2 at a molar ratio of isocyanate moieties to hydroxyl moieties of less than one; selecting at least one of the components to have a functionality that is greater than two to facilitate crosslinking; and reacting the isocyanate and polyol components in the presence of a catalyst to form a polyurethane polymer, said polyurethane polymer being free from any added tackifying and plasticizing agents, having a glass transition temperature of less than about 0°
C., having a moisture absorption of at least about 20% of its weight and/or a moisture vapor transmission rate of at least about 300 grams/meter2 /24 hours measured at 37°
C. and 90% relative humidity gradient, and having a peel adhesion to human skin of between about 0.3 and 4 newtons/cm width of the polymer wherein said polyurethane polymer is crosslinked to a crosslink density α
of between about 10-4 and 10-3 wherein α
is defined by the equation;
##EQU6## where i=1 to n where n is the number of the reactant components;Xi =the mole fraction of the ith component; Fi =the functionality of the ith component; r=the NCO/OH ratio; and Mw=the molecular weight of the polyol. transmission rate of at least about 300 grams/meter2 /24 hours measured at 37°
C. and a 90% relative humidity gradient, and a peel adhesion to human skin of between about 0.3 and 4 newtons/cm width of the polymer. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification