US1714831A - Process of producing fiber - Google Patents

Description

Patented May 28, 1929..

' UNITED STA j amen ALFRED TINGIIE, F OTTAWA, ONTARIO, CANADA.

PROCESS OF PRODUCING FIBER.

No Drawing.

' to be carried on at such temperature and under such conditions that any danger of over-cooking will be. avoided.

Further objects still are to provide a process to better adapt it to perform the functions required.

In consists essentially of the process herein described in detail in the accompanying specification.

' The process is of a type involving the digestion of a fiber-producing material with a solution of lime and sulphur. As a first step a raw material, which is preferably 'wood in a'convenient form is first digested with a solution of lime and sulphur, being essentially a solution of calcium polysulphidcs in water. The proportion of lime to sulphur is comparatively low, and I have found for instance, that the following pro-' portions are satisfactory: Wood, typically in the form of spruce chips weighed in air dry conditions, 100 lbs.; quicklime, 13 lbs.; sulphur (powdered finely), 6% lbs; water, a convenient quantity up to 100 gals.

The lime, sulphur and Water may be digested together before adding the wood and more water, or more conveniently, the lime,

sulphur and wood and water may be all digested together. The boiler used may be of steel unlined.

The temperature of digestion may range from 155 C. to 170 C. The mixture is boiled under a steam pressure of 65 to 100 lbs. to the square. inch, for a period of 6 to 12 hours.

The length of cooking varies according to the condition and nature of the wood.

It may be observed at this point, that the action in the process is so mild, that overcooking becomes almost impossible. Thus chips such as are prepared for sulphite or other digestion process may be mixed with quite fine shavings and all may be cooked together without danger of overcooking fine material in an efiort to fully cook the coarser.

The product of this digestion retains most of its original form and on discharge from the digester must be crushed or ground in an Application filed January 25, 1924. Serial No. 688,619.

edge runner, a heating engine or some similar- .some liquor which will largely eliminate the Dilute sulphuric acid is one (1 volume of 66 B6.

lime.

Such material is Very various.

acid to 10 vols. of water). Other acids may be used and I prefer as cheap, convenient and productive of a good pulp, to beat with the hot waste liquor from the digestion of wood by the sulphite process. This material is commonly known as sulphite waste liquor and contains an acid salt of calcium, but is capable of uniting with more lime, and so largely eliminating it from the polysulphide pulp.

The pulp produced above will have a dark colour, the tint depending on the details of treatment. It is however strong in fiber and long in fiber if the nature and previous treatment of the wood allows of this. Its colour can be improved by bleaching with hypo-chlorites in the usual manner, but this is not recommended, as a strong dark pulp is the object aimed atsomething to use in wrapping papers.

It is the less desirable to bleach this pulp because it is intended to include in woodtreated by this process the inner bark, discoloured shavings and such like matters at present considered refuse by most makers of pulp according to the older processes. Only outer bark need be excluded, and this because it is not fibrous and thus in no case a paper making material.

In the above described process the proportion of lime to wood, lime to sulphur and sulphur to wood, is much lower than in other processes of digestion with lime and then treating with a lime-eliminating material.

2. A process for producing fiber, which comprises digesting vegetable fiber material in an aqueous solution of lime and sulphur, then. treating with an aqueous acid solution designed to eliminate lime.

3. A process for producing fiber, which comprises digesting vegetable fiber material in an aqueous solution of lime and sulphur, then treating with a sulphite waste liquor.

4. A process for producing fiber, which comprises digesting vegetable fiber material in an aqueous solution of lime and sulphur, then treating with a lime eliminating material, and then removing the colouring niaterial from the fiber.

5. A process for producing fiber, which comprises digesting vegetable fiber material in an aqueous solution of lime and sulphur, then treating with a lime eliminating material, and then grinding the resulting material.

6. A process for producing fiber, which comprises digesting vegetable fiber mate- 'rial in an aqueous solution containing less than 15 per cent of lime and sulphur then treating with a lime eliminating material.

7. A process for producing fiber, which comprises digesting vegetable fiber material in an aqueous solution of'li-me and sulphur, then treating with a lime eliminating material, and then grinding and screening.

In witness whereof I have hereunto set my hand. ALFRED TINGLE.