Closed-cell phenolic foam having a uniform cell structure in which the cell walls are substantially free of both ruptures and perforations is disclosed. The phenolic foam has initial k values of less than 0.15 with substantially no increase of k value over time and good density and compressive strengths. The phenolic foam is prepared by foaming and curing a foamable phenolic resole composition containing an aqueous phenol formaldehyde resole, surfactant, fluorocarbon blowing agent, and optionally other additives with an acid foaming and curing catalyst in a substantially closed mold which exerts a restraining pressure on the foaming composition in excess of ambient atmosphericpressure of greater than about 3 pounds per square inch. The aqueous phenol formaldehyde resole is essentially a phenol formaldehyde condensation polymer having a molar ratio of formaldehyde to phenol of from about 1.7:1 to 2.3:1, preferably from 1.75:1 to 2.25:1 and most preferably about 2:1. The resole has a weight average molecular weight greater than 800 and preferably from 950-1500. The resole also has a number average molecular weight greater than about 350 and preferably from about 400 to about 600 and a dispersivity greater than about 1.7, preferably from 1.8 to 2.6. The acid foaming and curing catalyst is an anhydrous aryl sulfonic acid having a pKa less than about 2.0 and which changes the compatibility of the phenolic resole with water. The preferred anhydrous aryl sulfonic acid is a combination of toluene sulfonic acid and xylene sulfonic acid.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. Application Ser. No. 282,021, filed July 10, 1981 abandoned.
USPTO Field of Search
521/121
521/181
521/133
Related Patents
6586484 - Phenol foam - Owned by Owens Corning Fiberglas Technology, Inc. (Summit, IL)
To provide a type of phenol foam characterized by the fact that the phenol foam is formed by using a hydrocarbon as the foaming agent. The phenol foam has excellent heat-insulating performance, high compressive strength and other mechanical strengths, improved brittleness and is friendly to the environment of the earth.
This invention is concerned with a method for producing phenol resin foam possessing a compact cellular structure, a high closed cell ratio and improved heat resistance. The method consists of using a resole type phenolic resin having a number average molecular weight of 150-400, surface active agents, blowing agents and curing agents, wherein at least two surface active agents are chosen from general formulas A and B, but a selection of each type must be employed ##STR1## where R.sub.1 is a saturated aliphatic hydrocarbon group of 8-14 carbon atoms and/or a 2-phenylpropyl group, and m and n are integers and meet the requirement: ##EQU1## R.sub.2 is a saturated aliphatic hydrocarbon group of 4-12 carbon atoms, M is a hydrogen atom or SO.sub.2 Na, and x is an integer of 4-110.
This invention relates to the production of low density resol foams from resol resins. The phenolic foams have a density of 2.0 pounds per cubic foot or less and are produced with a blended surfactant.
Phenolic foams having a cell structure that is resistant to rupture under pressure and a slow deterioration of thermal insulation value are claimed. These foams can be cured to achieve dimensional stability without substantial adverse affect on their structure.
The physical and mechanical properties of closed cell phenolic foam are improved by incorporating into certain foamable phenolic resole compositions small quantities of alkyl glucosides, particularly methyl glucosides. The alkyl glucosides also improve the process for preparing the closed cell phenolic foam.
