Gradient foaming method for preparation of phenolic foam

Abstract

The invention discloses a gradient foaming method for preparation of phenolic foam, which is to use a gradient foaming agent to prepare the phenolic foam with excellent performance. The gradient foaming agent composites multiple organic solvents with the boiling points from 25 DEG C to 90 DEG C, the boiling points of the organic solvents are in gradient distribution from low to high, and the organic solvents comprise multifunctional components of foaming, transition and absorption of heat, so as to act on different actions in the three curing and foaming stages for the phenolic foam, namely normally foaming in the earlier curing and foaming stage of the resin, stably foaming in the middle stage, and reasonably absorbing surplus heat in the later stage to prepare the phenolic foam with the excellent performance. The phenolic foam is prepared from the following materials in parts by weight: 4-10 parts of the gradient foaming agent, 80-100 parts of phenolic resole resin, 3-7 parts of a surfactant, and 5-20 parts of a curing agent. The phenolic foam prepared by the method disclosed by the invention is uniform in density, high in tensile strength of the fracture surface and percentage of close area, complete in foam wall, low in water absorption, excellent in performance, and capable of being widely applied to the high and new technical fields such as materials for energy conservation, thermal insulation, fire protection and flame retardance.

Description

technical field [0001] The invention relates to a method for preparing phenolic foam, in particular to using a gradient foaming agent to prepare phenolic foam with excellent performance, and belongs to the field of high-tech materials such as flame retardancy and heat preservation. Background technique [0002] Phenolic foam is a new generation of fireproof and thermal insulation materials. It has many excellent properties such as light weight, non-toxic, flame retardant, low thermal conductivity, corrosion resistance, anti-aging, sound absorption, etc. It has great practical value as a thermal insulation material. [0003] Phenolic foam is generally foamed and cured under the condition of 50°C-80°C. When curing, it will exotherm itself, and the maximum temperature can reach above 140°C (European patent: EP 0 579 321 B1). At present, the traditional foaming process generally adds low-boiling solvents such as pentane, petroleum ether, and organic fluorine as foaming agents. W...

AI Technical Summary

Problems solved by technology

At present, the traditional foaming process generally adds low-boiling-point solvents such as pentane, petroleum ether, and organic fluorine as foaming agents. When the resin is cured, the temperature of the system increases, the gas pressure increases, and the heat insulation of the foam itself, The accumulated heat cannot be released, and the gas pressure in the cells is too high, which will easily lead to a large number of large cells, broken cells, combined cells, collapsed cells, and through holes in the cells, resulting in uneven density and low strength of the prepared phenolic foam. , Incomplete pore wall, high water absorption, high brittleness and easy to drop powder and slag, which seriously affect the application of phenolic foam in high-performance occasions

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