| 摘要 |
<p>1404042 Granular phenol-formaldehyde resins and foams thereof AISIN CHEMICAL CO Ltd 18 Oct 1972 [30 Oct 1971 23 March 1972 (4)] 48021/72 Headings C3R C3N and C3C Granular phenol-formaldehyde resin is produced by spraying a liquid material containing an initial condensation product of a phenolaldehyde resin into an atmosphere heated to a temperature higher than the melting point of the initial resin and bringing the liquid resin particles thus produced into contact with a gas, e.g. air, at a temperature lower than the melting point of said initial resin to solidify the particles. The particles are generally spherical and in the examples vary in size from 70-300 microns and have m.p. ranging from 65-85‹ C. The resin may be of the novolak and/or resol type and may be modified with melamine, urea, guanidine or dicyandiamide. The resin may include a foaming agent such as dinitropentamethylenetetramine, azodicarboxylic acid amide, hydrazine or sodium hydrogen carbonate, which acts at the final curing temperature to generate a gas. Suitable phenols for the resin include phenol itself, meta-C 1-6 alkyl phenols, metaalkoxyphenols and meta-halogenated phenols. The granulating process may be carried out as shown. The liquid resin material from heated tank 18 is sprayed through atomizer 26 into the upper cylindrical portion 30 of drying tank 28 which is supplied with hot air, e.g. at 100- 200‹ C. from furnace 38. The liquid resin particles produced then pass into lower conical portion 32 of tank 28 which is cooled with air, e.g. at 5-50‹ C. fed from fan 56. A lubricant, e.g. stearic acid bis-amide may be fed in with the cool air through conduit 54 from supply device 58. The discharged resin is fed to separator device 66 and the granules are collected by cyclone 74 and stored in reservoir 76. Examples 1-6 describe the preparation of granular phenolic resins using the above apparatus from phenol/HCHO resol resin optionally in the presence of stearic acid bisamide a phenol/HCHO novolak resin and a phenol/HCHO novolak/resol mixture. In example 7 phenol- HCHO novolak and/or resole resin granules which may be coated with stearic acid bisamide are used to coat silica sand by the hot mulling method, for use in shell moulds. In Example 9 a mixture of 100 p.b.w. resin granules produced from phenol, hexamethylol-melamine and HCHO, 50 p.b.w. alpha cellulose fibres, 4 p.b.w. 10% NaOH, 2 p.b.w. zinc stearate is blended on hot rolls to form a sheet. In Example 10 a mixture of 100 p.b.w. of the resin of Example 9, 70 p.b.w. wood powder, 20 p.b.w. talc, 1 p.b.w. MgO, 2 p.b.w. zinc stearate is blended as above to form a sheet. In Example 11 150 g. of the resin of Example 9 are moved and heated with 5 Kg. silica sand and 5 g. calcium stearate to form resin coated sand for use in shell moulds. In Example 13 a resin prepared from urea, phenol and paraformaldehyde is used to coat sand as in Example 11. In Examples 14-16, 100 p.b.w. sand are coated with 3 p.b.w. of a granular phenol-HCHO resole resin containing 3% (or 10%) by wt. of dinitropentamethylenetetramine or 10% by wt. of diazocarboxylic acid amide as foaming agent, 0À1 p.b.w. calcium stearate being added to the mixture.</p> |
