| 摘要 |
Keratin is prepared for use in moulding compositions by crushing the raw material such as hoofs or horns and then subjecting the product to a selective grinding and sifting process in which the impurities are largely removed with the particles which pass through the finer meshes of the sieves while the coarser particles of keratin of a higher degree of purity are separated and subjected to a further stage of grinding. The raw material may be submitted to a preliminary purification which comprises washing, drying for 24-36 hours at 80-90 DEG C. and cooling. The crushing which is preferably effected in a hammer mill, is followed by grinding in pin mills firstly at 2,000-3,000 revolutions per minute and finally at 4,000-6,000 revolutions per minute as a result of which the ash content is reduced from 2.5 to 0.2 per cent. The purified product may be bleached by steeping for 6-24 hours in dilute ammonia solution, removing the aqueous liquor by centrifuging, rendering acid by iron-free hydrochloric acid and then adding the sodium salt of formaldehyde sulphoxylic acid with or without sodium hyposulphite with stirring. The bleached material may be washed and dried at 45-50 DEG C. The p purified product may be incorporated with phenol-formaldehyde resins or with urea- or melamine-formaldehyde condensation products and moulded at 145-160 DEG C. at a pressure of 1-1 1/2 tons per square inch.ALSO:Keratin is prepared for use in moulding compositions by crushing the raw material such as hoofs or horns and then subjecting the product to a selective grinding and sifting process in which the impurities are largely removed with the particles which pass through the finer meshes of the sieves while the coarser particles of keratin of a higher degree of purity are separated and subjected to a further stage of grinding. The raw material may be submitted to a preliminary purification which comprises washing, drying for 24-36 hours at 80-90 DEG C. and cooling. The crushing which is preferably effected in a hammer mill, is followed by grinding in pin mill firstly at 2,000-3,000 revolutions per minute and finally at 4,000-6,000 revolutions per minute as a result of which the ash content is reduced from 2.5 to 0.2 per cent. The purified product may be bleached by steeping for 6-24 hours in dilute ammonia solution, removing the aqueous liquor by centrifuging, rendering acid by iron-free hydrochloric acid and then adding the sodium salt of formaldehyde sulphoxylicacid with or without sodium hydrosulphite with stirring. The bleached material may be washed and dried at 45-50 DEG C. The purified product may be incorporated with phenol-formaldehyde resins or with urea- or melamine-formaldehyde condensation products and moulded at 145-160 DEG C. at a pressure of 1-1 1/2 tons per square inch.
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