| 摘要 |
The present invention relates to a process for the preparation of phenol-formaldehyde foams by mixing a resol phase having a viscosity of between 8 and 60 poises and a novolac phase comprising a true novolac, a blowing agent, phenolsulphonic acid and, optionally, phenol, the relative amounts of resol phase and of novolac phase being such that the resol phase represents 45 to 75% by weight of the mixture. |
