Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes

Definitions

• This invention relates to a process of treat ing woody materials, (that is to say, cellulose fibers cemented together by lignin),
• lignin refers to a group of substances developed during the process of the plant growth, and which differ from the cellulose fibers in that they (the lignin substances) are soluble in certain solvents, such as dilute acids and dilute alkalies, in which solvents the cellulose fibers arenot readily soluble.
• sulphite process is an acid process in which the wood is treated under pressure in an aqueao ous sulphurous acid solution or solution con- 7 taining sulphites of the alkalies or alkali earth metalstogether with sulphurous acid.
• the strength of the acid solution varies within small limits according to the nature of the raw material. Generally stated, it contains about 3.5% free sulphur dioxide and 1.15 of sulphur dioxide in the form of sulphites of calcium and magnesium.
• the cooking as the treatment is called, is done under a pressure of fromsixty-five to seventy-five pounds per square inch, with temperatures ranging from two hundred and thirty to three hundred degrees, F., while the time of cooking varies from twenty-four to sixty hours.
• soda process is an alkaline process in which the woody material is subjected, under pressure, to the action of dilute aqueous caustic soda (8 to 10% caustic soda by weight).
• the pressures employed in this process vary from seventy-five to two hundred pounds per square inch with the temperatures at 330 F., to 380 F., the time of cooking varying from four or five hours to twelve hours.
• the third process is an alkaline process.
• a better 'name would be the sulphide process, since the digesting liquor to which the woody material is subjected contains chiefly sodium hydroxide and sodium sulphide and small amounts of sodium carbonate and sodium phosphate.
• this liquor possibly 5% caustic soda and 3 to 4% sodium sulphide, by weight, are employed and the cooking takes place under pressure of approximately one hunderd pounds per square inch, and requires from two to six hours.
• Another object is to provide a rocess for cooking woody materials to free t em from lignin and obtain the cellulose fibers for paper makin and other uses, without the necessity of per orming the operation under pressure, and to materially shorten the time consumed in the operation.
• Another object is to provide a process that will thus free the fibers from the lignin without injury to the fibers themselves.
• the invention consists in subjecting the woody materials for a short period of time, varying from fifteen to forty-five minutes, and at atmospheric pressure, to the action of an aqueous solution containing approximately sodium hydroxide, by weight, and preferably a small percentage each of sodium thiosulphate, sodium borate, and sodium phosphate tribasic.
• This solution is heated in an open vessel to a temperature of approximately 260 F., and the woody material is then placed therein.
• the length of time during which the woody materials are subjected to the action of this solution will vary with the character of the materials themselves.
• the fibers can be freed from the li gnin in approximately eighteen minutes. Defiberized spruce will require treatment for approximately fifteen minutes, while flax straw will require only about twelve minutes, though with higher temperatures this time is greatly reduced. Bagasse should be treat- 1ed for approximately one-half minute or ess.
• the outstanding characteristic of the invention lies in subjecting the woody mate-' rials at atmospheric pressure to a drastic solution of caustic soda, ranging from 40% to 55% but it will be generally found that a solution approximating 50%, or slightly less, of caustic soda will be efficient.
• the method of treating woody materials to obtain fibers therefrom for paper making and other uses which consists in subjecting said materials to the action of an aqueous solution containing approximately 50% of sodium hydroxide by weight.
• the method of treating woody materials to obtain fibers therefrom for paper making and other uses which consists in subjecting said materials to the action of an aqueous solution containing on the order of 50% of sodium hydroxide by weight; w
• the method of treating woody materials to obtain fibers therefrom for paper making and other uses which consists in subjecting said materials to the action of an aqueous solution containing on the order of 50% sodium hydroxide and 3% sodium thiosulphate, each by weight.
• the method of treating woody materials to obtain fibers therefrom for paper making and other uses which consists in subjecting said materials to the action of an aqueous solution containing on the order of 50% of sodium hydroxide by weight at a temperature of approximately 260 F.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23870225

Family Applications (1)

Country Status (3)

Cited By (2)

• 0
  • BE BE379997D patent/BE379997A/xx unknown
• 1930
  • 1930-07-26 US US471094A patent/US1868570A/en not_active Expired - Lifetime
• 1931
  • 1931-05-02 GB GB13017/31A patent/GB387651A/en not_active Expired

Also Published As

Similar Documents