Phenolic foams foaming processes

Foaming Mechanism. The process for producing resol-type phenolic foams is simUar to that of polyurethane foam. The foaming process in phenolic foam may be divided into five steps. This process does not progress by step-by-step, but the several phenomena progress spontaneously. 

Foaming Process of Resol-Type Foam. The foaming processes for phenolic foam of both the resol type and benzylic-ether type are the same as those for rigid polyurethane foams. The block-foaming process (slab foaming), pouring process, continuous-laminate process, and spray process are used. See Figure 57. 

In Japan very large quantities of metal-siding board (consisting of metal sheet/phenolic foam/flexible-facing material) are manufactured as exterior materials in budding construction. This material is also manufactured using the same principle as that in the laminate process. 

Processing Facilities. The phenolic-foam-producing process is simUar to that used with rigid polyurethane foams. Production of composite sandwich panels, board-type products, pipe covers, are possible. 

Floral Foam. In the U.S. and Western European countries the most popular use of phenol foam for floral applications is a water-soaked foam using a resol-type composition. It is important to maximize the open-cell content in order to inq)rove its water penetration. Floral foam is produced as laige block or slab by a batch process. The foam is easily cut and packaged with a minimum of loss due to waste. Floral foam is commonly used for living flowers, but is not used for dried and artificial flowers. 

Autoweave [49] was a process developed by Brochier in France and licenced exclusively to Avco/Textron in the USA. The radial reinforcement in Autoweave is a screw-like reinforced phenolic resin rod, which is produced as a continuous stock, cut to length and inserted by computer control into an expendable low cost phenolic foam mandrel. The axial and circumferential reinforcements, which can be either dry fiber or a prepreg, are then positioned precisely in the radial corridors to produce a 3-D preform. 

Yun and Lee (2004) investigated pultrusion of phenolic foam composites. The effect of process variables on the foaming characteristics of phenolic resin during pultrusion was studied experimentally with the consideration of variables such as the heating temperature, the pulling speed and the mass fraction of the blowing agent. 

Yun, M. S. and Lee, W. I. (2004), Process optimization of pultrusion process of phenolic foam composites , SAMPE 2004, Long Beach, USA. 

Polyphenols. Another increasingly important example of the chemical stabilization process is the production of phenolic foams (54-57) by cross-linking polyphenols (resoles and novolacs) (see Phenolic Resins). The principal features of phenolic foams are low flammability, solvent resistance, and excellent dimensional stability over a wide temperature range (54), so that they are good thermal-insulating materials. 

Several manufacturing processes can be used to produce phenolic foams (54, 74) continuous production of free-rising foam for slabs and slab stock similar to that for polyurethane foam (65,75) foam-in-place batch process (56,76) sandwich paneling (58,77,78) and spraying (65,79). 

Ammonia is used in the fibers and plastic industry as the source of nitrogen for the production of caprolactam, the monomer for nylon 6. Oxidation of propylene with ammonia gives acrylonitrile (qv), used for the manufacture of acryHc fibers, resins, and elastomers. Hexamethylenetetramine (HMTA), produced from ammonia and formaldehyde, is used in the manufacture of phenoHc thermosetting resins (see Phenolic resins). Toluene 2,4-cHisocyanate (TDI), employed in the production of polyurethane foam, indirectly consumes ammonia because nitric acid is a raw material in the TDI manufacturing process (see Amines Isocyanates). Urea, which is produced from ammonia, is used in the manufacture of urea—formaldehyde synthetic resins (see Amino resins). Melamine is produced by polymerization of dicyanodiamine and high pressure, high temperature pyrolysis of urea, both in the presence of ammonia (see Cyanamides). 

Nonwoven manufacturing, cotton, 3 18 Nonwoven materials, 24 620. See also Nonwoven fabrics Nonwoven processes, 17 496-497 Nonwovens. See also Nonwoven fabrics air-laid, 17 503 defined, 17 495-496 foam-bonded, 17 510 needled, 17 506, 507 thermal-bonded, 17 511-512 Nonwoven textile materials, 11 178-180 4-Nonylphenol (PNP), 2 225-226 health and safety data, 2 220t physical properties of, 2 205t Nonyl phenol, 10 429 8-Nonynoic acid, 5 34t... 

Phenolic novolacs, 18 760-761 Phenolic resin adhesives, 18 783-784 Phenolic resin can coatings, 18 38 Phenolic resin composites, 18 792-794 Phenolic resin drying-oil varnishes, 18 783 Phenolic resin fibers, 18 797-798 mechanical properties of, 18 798 Phenolic resin foam, 18 795-796 Phenolic resin manufacturers, U.S., 18 774 Phenolic resin polymerization, 18 760-765 alkaline catalysts in, 18 762-765 neutral catalysts in, 18 761-762 strong-acid catalysts in, 18 760-761 Phenolic resin prepregs, 18 793 Phenolic resin production unit, 18 766 Phenolic resins, 10 409 18 754-755, 756-802 22 10 26 763 in abrasive materials, 18 786-787 in air and oil filters, 18 790 additional reactants in, 18 759 analytical methods for, 18 774-779 applications of, 18 781-798 batch processes for, 18 766 from biomass and biochemical processes, 18 769-770... 

This process is generally used for thermosets, such as polyurethane, polyisocyanurate, phenolic, unsaturated polyester and silicone foams, but it is also used for plastisols or PVC... 

Toluene is used more commonly than the other BTXs as a commercial solvent. There are scores of solvent applications, though environmental constraints and health concerns diminish the enthusiasm for these uses. Toluene also is used to make toluene diisocyanate, the precursor to polyurethane foams. Other derivatives include phenol, benzyl alcohol, and benzoic acid. Research continues on ways to use toluene in applications that now require benzene. The hope is that the dealkylation-to-benzene or disproportionation steps can be eliminated. Processes for manufacturing styrene and terephthalic acid—the precursor to polyester fiber—are good, commercial prospects. 

Lin et al. ( 6) measured the emulsion capacity of defatted sunflower seed products. Data in Table VII show that sunflower flour was superior in emulsifying capacity to all other products tested. The emulsions were in the form of fine foams and were stable during subsequent heat treatments. The diffusion-extraction processes employed to remove phenolic compounds dramatically reduced emulsion capacity, although isolating the protein improved emulsion capacity to some extent. 

Novolac and resol cold hardening oligomers habe been used 19-75-99). In the case of resol foams the process technology is not different from that used for epoxy foams. Glass, phenolic resins, carbon, polystyrene, polyacrylonitrile and poly(vinylidene chloride) microspheres have been used as fillers ... 

Fig. 22a and b. Behavior of syntactic foams during thermal treatment. Key a Thermogram of the hardening process for (1) Unfilled epoxy and (2) Epoxy syntactic foam with phenolic microspheres, b Glass transition temperature of the epoxy binder versus concentration of phenolic microspheres 1621... 

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