Crosslinked hydrophilic foams and method

• US 4,137,200 A
• Filed: 06/10/1977
• Issued: 01/30/1979
• Est. Priority Date: 10/09/1973
• Status: Expired due to Term

• Current Assignee: Hampshire Chemical Corp. (Dow, Inc.)
• Original Assignee: WR Grace & Company
• Inventors: Wood, Louis L., Frisch, Kurt C.
• Primary Examiner(s): Jacobs, Lewis T.
• Application Number:
  US05/805,458
• Time in Patent Office: 599 Days
• Field of Search: 260/2.5 AD, 260/2.5 AM, 260/2.5 A, 260/2.5 AP, 260/2.5 BD, 260/29.27 N
• US Class Current: 521/159
• CPC Class Codes: A61K 6/893 Polyurethanes
• CPC Class Codes: A61K 8/0208 Tissues; Wipes; Patches
• CPC Class Codes: A61K 8/87 Polyurethanes
• CPC Class Codes: A61K 9/0036 Devices retained in the vagina or cervix for a prolonged period, e.g. intravaginal rings, medicated tampons, medicated diaphragms
• CPC Class Codes: A61L 15/425 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61Q 19/00 Preparations for care of the skin
• CPC Class Codes: C02F 3/10 Packings; Fillings; Grids packing elements in general B01J19/30, B01J19/32
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/4833 Polyethers containing oxyethylene units
• CPC Class Codes: C08G 18/6677 having at least three hydroxy groups
• CPC Class Codes: C08G 18/8029 Masked aromatic polyisocyanates
• CPC Class Codes: C08G 2110/0083 prepared using water as the sole blowing agent
• CPC Class Codes: C08G 2310/00 Agricultural use or equipment
• CPC Class Codes: C08L 75/16 having terminal carbon-to-carbon unsaturated bonds
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage
• CPC Class Codes: Y10S 521/905 Hydrophilic or hydrophobic cellular product

Abstract

The invention disclosed is for new improved hydrophilic crosslinked polyurethane foams prepared by reacting a blend of a monomeric polyol and polyoxyalkylene glycol (the --OH groups of said blend being capped with a polyisocyanate) with large amounts of an aqueous reactant. The resultant foams may be characterized with a broad spectrum of improved properties including hydrolytic stability and tensile strength.

Claims

1. A crosslinked hydrophilic foam having a three-dimensional network comprising the reaction product of

A. isocyanate capped prepolymers consisting of a mixture of

(1) an isocyanate capped hydrophilic polyoxyethylene diol, said diol having an ethylene oxide content of at least 40 mole percent;

and

(2) an isocyanate capped polyol having a hydroxyl functionality in the range 3 to 8 prior to capping;

said isocyanate capped polyol being present in an amount in the range 2.9 to 50% by weight of (1) and (2);

B. 3.2 to 7.9% by weight of A and B of a polyisocyanate having an isocyanate functionality in the range 2.0 to 2.8; and

C. 6.5 to 390 moles of water for each mole of unreacted isocyanate.

2. A foam as in claim 1 wherein the polyol is trimethylolpropane.

3. A foam as in claim 1 wherein the polyol is glycerol.

4. A foam as in claim 1 wherein the polyol is pentaerythritol.

5. The process of forming a crosslinked hydrophilic urethane foam which comprises admixing a hydrophilic polyoxyethylene diol having an ethylene oxide content of at least 40 mole percent with a polyol having a hydroxyl functionality in the range 3 to 8, said polyol being present in the admixture in an amount in the range 1.0 to 20% by weight, reacting with the admixture at a temperature in the range 0 to 120°

C. an amount of a polyisocyanate having an isocyanate functionality in the range 2.0 to 2.8 equal to 1.8-1.9 NCO to OH equivalents for a time sufficient to cap substantially all the hydroxyl groups of the admixture, adding additional polyisocyanate having an isocyanate functionality in the range 2.0 to 2.8 to provide 0.1-0.3 equivalents of NCO per initial equivalent of OH in excess of the theoretical amount necessary to react with the hydroxyl groups and thereafter adding 6.9 to 390 moles of water for each mole of unreacted isocyanate in the admixture.

6. A method as in claim 5 wherein the polyol is trimethylolpropane.

7. A method as in claim 5 wherein the polyol is glycerol.

8. A method as in claim 5 wherein the polyol is pentaerythritol.

9. A crosslinkable hydrophilic urethane foam forming composition upon the addition of an aqueous reactant comprising

(1) a isocyanate capped hydrophilic polyoxyethylene diol, said diol having an ethylene oxide content of at least 40 mole percent;

(2) an isocyanate capped polyol having a hydroxyl functionality in the range 3 to 8 prior to capping;

said isocyanate capped polyol being present in an amount in the range 2.9 to 50% by weight of (1) and (2); and

(3) 3.2 to 7.9% by weight of the composition of a polyisocyanate having an isocyanate functionality in the range 2.0 to 2.8.

10. The process of forming a crosslinkable hydrophilic urethane foam forming composition which comprises admixing a hydrophilic polyoxyethylene diol having an ethylene oxide content of at least 40 mole percent with a polyol having a hydroxyl functionality in the range 3 to 8, said polyol being present in the admixture in an amount in the range 1.0 to 20% by weight, reacting with the admixture at a temperature in the range 0 to 120°

C. an amount of a polyisocyanate having an isocyanate functionality in the range 2.0 to 2.8 equal to 1.8-1.9 NCO to OH equivalents for a time sufficient to cap substantially all the hydroxyl groups of the admixture and thereafter adding additional polyisocyanate having an isocyanate functionality in the range 2.0 to 2.8 to provide 0.1-0.3 equivalents of NCO per initial equivalent of OH in excess of the theoretical amount necessary to react with the hydroxyl groups.