The present invention is directed to aqueous phenol formaldehyde resoles that have particular application in manufacturing phenolic foam insulation. The resoles are essentially phenol formaldehyde condensation polymers having molar ratios 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 resoles have a weight average molecular weight greater than 800 and preferably from 950-1500. The resoles also have a number average molecular weight greater than 350 and preferably from about 400 to about 600 and a dispersivity greater than about 1.7, preferably from 1.8 to 2.6. Phenol formaldehyde resoles having these characteristics are processable into phenolic foams having a low k value and having other physical characteristics which make the phenolic foam especially useful as an insulation material. The present invention is also directed to foamable phenolic resole compositions prepared from the phenolic resoles and phenolic foams prepared from the compositions.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of application Ser. No. 396,500, filed July 9, 1982, now abandoned, which is a continuation-in-part of U.S. application Ser. No. 282,021, filed July 10, 1981, now abandoned.
In a method for producing resol type phenol resin foams by using starting material for the foams prepared by blending a resol type phenol resin, a blowing agent and a catalyst, a low molecular weight resol type phenol resin with the number average molecular weight of less than 200 and a high molecular weight resol type phenol resin with the number average molecular weight of greater than 200 are mixed at a weight ratio of from 5/95 to 80/20 and used as the resol type phenol resin. The resol type phenol resin foams are excellent in adhesion, fire-proofness capable of foaming cure in a short time and useful for sprayed-in-place foaming, etc. The phenol resin foams produced by the invention are capable of integral foaming with rigid urethane resin foam layer into foamed laminates of excellent thermal insulation, fire-proofness, etc.
A mixture of CFC-113 and CFC-123 and/or CFC-123a where CFC-123 or CFC-123a is a significant portion of the total composition has been found to result in improved blowing agent performance in phenol-formaldehyde foams compared to CFC-113. The use of CFC-123 (or CFC-123a, or both), in combination with CFC-113 improves resole resin solubility and mixed ingredient solution stability, prior to foaming. In addition, because of the lower molecular weight of CFC-123 (or CFC-123a) compared to CFC-113 better blowing agent efficiency will be realized per unit weight. Also, the lower boiling points of CFC-123 and CFC-123a as compared to CFC-113 results in a more ready conversion of dissolved blowing agent to released gaseous blowing agent by the exothermic phenolic resin polymerization. And because of the lower molecular weight and lower boiling point factors, a lower density foam is realized.
A mixture of CFC-113 and CFC-123 and/or CFC-123a where CFC-123 or CFC-123a is a significant portion of the total composition has been found to result in improved blowing agent performance in phenol-formaldehyde foams compared to CFC-113. The use of CFC-123 (or CFC-123a, or both), in combination with CFC-113 improves resole resin solubility and mixed ingredient solution stability, prior to foaming. In addition, because of the lower molecular weight of CFC-123 (or CFC-123a) compared to CFC-113 better blowing agent efficiency will be realized per unit weight. Also, the lower boiling points of CFC-123 and CFC-123a as compared to CFC-113 results in a more ready conversion of dissolved blowing agent to released gaseous blowing agent by the exothermic phenolic resin polymerization. And because of the lower molecular weight and lower boiling point factors, a lower density foam is realized.
A method and apparatus are provided for encapsulating a workpiece in a material having a lower melting temperature than that of the material for the workpiece to form an encapsulated block of standardized size and shape which may be mounted in a standardized fixture to facilitate machining on the workpiece. The invention includes both specialized molds for use in encapsulating a workpiece for various types of machining and systems for clamping and injecting encapsulant into such molds under pressure. After machining on a given side, a block is re-inserted in the appropriate mold and re-encapsulated to standardize size and shape for a subsequent machining operation. The process of machining and re-encapsulation are repeated until all sides of the workpiece requiring machining have been machined, at which time the encapsulant is removed from the workpiece, normally by being heated and melted.
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.
