Phenolic foams
AssigneeMonsanto Company
InventorsRobert C. Clark, Dean L. Kavanagh
Life of this patent
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Abstract
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.
Claims11
A phenolic foam derived from a composition comprising a phenolic resole with a formaldehyde to phenol mole ratio of from 1.2:1 to 2.5:1, a blowing agent having a thermal conductivity of less than 0.016 watts/m.degree. C. and from 0.5 to 6 wt.% of a surfactant based on the weight of the resole, said foam possessing:
- a. a density of from 30 to 70 kg/m.sup.3, and a closed-cell content of at least 85% as measured by an air pycnometer according to ASTM test method D-2856 (Procedure C);
- b. a thermal conductivity after 100 days at 23.degree. C. and 50% relative humidity of less than 0.02 watts/m.degree. C., and a value of .DELTA.k/.DELTA.lnt of less than 0.5.times.10.sup.-3 where .DELTA.k in watts/m.degree. C. is k.sub.100 minus k.sub.1 and .DELTA.lnt in days is lnt.sub.100 minus lnt.sub.1 ;
- c. an isotropic pressure, required to reduce the closed-cell content of the foam by at least 10 percent, in excess of 1.75 kg/cm.sup.2 ;
- and
- d. said foam being hardened and having a degree of cure which is at least substantially equal to the degree of cure achieved by heating the hardened foam to a temperature of 60.degree. C. for at least 18 hours.
The foam of claim 10, wherein the resole reactivity number is about 3 to 7 at an acid catalyst concentration of 1.5%.
A phenolic foam derived from a composition comprising a dispersed salt resole with a viscosity of from 80,000 to 600,000 centipoise at 25.degree. C. and a formaldehyde to phenol mole ratio of 1.5:1 to 2.2:1;
- from 1.0 to 5.0% by weight, based on the resole weight, of a nonionic surfactant;
- and a blowing agent with a thermal conductivity of less than 0.014 watts/m.degree. C.;
- the foam possessing:
- a. a density of from 40 to 60 kg/m.sup.3 and a closed-cell content of at least 90% as measured by an air pycnometer according to ASTM test method D-2856 (Procedure C);
- b. a thermal conductivity after 100 days of less than 0.02 watts/m.degree. C. and a value of .DELTA.k/.DELTA.lnt of less than 0.5.times.10.sup.-3 where .DELTA.k in watts/m.degree. C. is k.sub.100 minus k.sub.1 and .DELTA.lnt in days is lnt.sub.100 minus lnt.sub.1 ;
- c. a pressure, required to reduce the closed-cell content of the foam by at least 10 percent, in excess of 1.75 kg/cm.sup.2 ;
- and
- d. said foam being hardened and having a degree of cure which is at least substantially equal to the degree of cure achieved by heating the hardened foam to a temperature of 60.degree. C. for at least 18 hours.
Dependencies are inferred from the claim text.