Method of making expanded polyvinyl alcohol-formaldehyde reaction product and product resulting therefrom

• US 2,609,347 A
• Filed: 05/27/1948
• Issued: 09/02/1952
• Est. Priority Date: 05/27/1948
• Status: Expired due to Term

• Current Assignee: Lumley Wilson Christopher
• Original Assignee: Lumley Wilson Christopher
• Inventors: LUMLEY WILSON CHRISTOPHER
• Application Number:
  US03/029,657
• Time in Patent Office: 1,559 Days
• US Class Current: 521/87
• CPC Class Codes: C08F 16/06 Polyvinyl alcohol ; Vinyl alcohol
• CPC Class Codes: C08F 2810/20 leading to a crosslinking, either explicitly or inherently
• CPC Class Codes: C08F 8/28 Condensation with aldehydes or ketones
• CPC Class Codes: C08F 8/32 by reaction with amines
• CPC Class Codes: C08F 8/48 Isomerisation; Cyclisation
• CPC Class Codes: C08J 2329/14 Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08J 9/30 by mixing gases into liquid compositions or plastisols, e.g. frothing with air
• CPC Class Codes: Y10S 264/05 Use of one or more blowing agents together
• CPC Class Codes: Y10S 264/13 Cell size and distribution control while molding a foam

Claims

1. THE METHOD OF MAKING A SPONGE MATERIAL HAVING INTERCONNECTED PORES BY REACTING POLYVINYL ALCOHOL AND FORMALDEHYDE, WHICH COMPRISES:

PROVIDING AN AQUEOUS SOLUTION OF FORMALDEHYDE, POLYVINYL ALCOHOL CONTAINING LESS THAN 10% RESIDUAL HYDROLYZABLE MATERIAL IN THE MOLECULE, AN ACID CATALYST WHICH THE ACID FUNCTIONAL GROUP IS INORGANIC AND HAVING A DISSOCIATION CONSTANT OF AT LEAST 10-2 AND A FROTH-STABILIZING WETTING AGENT SOLUBLE IN AND SUBSTANTIALLY STABLE TO SAID SOLUTION;

FORMING A SUBSTANTIALLY STABLE AND HOMOGENEOUS FROTH WITH SAID SOLUTION STABILIZED WITH THE WETTING AGENT;

REACTING THE POLYVINYL ALCOHOL AND FORMALDEHYDE IN THE SOLUTION THEREBY CAUSING GELLATION AND SOLIDIFICATION OF THE FROTH WITH THE PRODUCTION OF INTERCONNECTED PORES SIMULTANEOUSLY WITH THE PROGRESSION OF THE REACTION, THE FROTH BEING FORMED PRIOR TO APPRECIABLE REACTION BETWEEN THE POLYVINYL ALCOHOL AND THE FORMALDEHYDE;

AND STOPPING SAID REACTION WHEN APPROXIMATELY 35-80% OF THE HYDROXYL GROUPS OF THE POLYVINYL ALCOHOL HAVE BEEN REACTED WITH THE FORMALDEHYDE.