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
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
  • D21C1/06—Pretreatment of the finely-divided materials before digesting with alkaline reacting compounds

Definitions

• the present invention relates to the manufacture of chemomechanical pulp from lignocellulose containing materials.
• this invention relates to a method of manufacture of chemomechanical pulps involving heating and defi'brating same in. an atmosphere of vapor at elevated temperature and under corresponding pressure of im pregnated chips.
• chips in this specification, will be understood to designate all kinds of lignocellulose material subject to disintegration.
• chemomechanical pulps in which the yield is as high as 80 to 85 percent, by impregnating lignocellulose containing material with sulfite solutions of various pH value, and thereafter heating the impregnated material in an atmosphere of saturated steam under pressure at temperatures exceeding 100 C., preferably within the range of 150 C. and 200 C., and subsequently subjecting the impregnated material to defibration.
• the equipment usually employed for such process comprises a steam container, a compression apparatus for the steamed chips and a vessel containing the impregnating solution in which the compressed chips are allowed to expand and take up sulfite solution, as is disclosed, for example, in copending application Ser. No. 237,911 filed Nov. 15, 1962, by Arne Johan Arthur Asplund.
• the concentration of the alkali solution is determined by the quantity of base which it is intended, the chips should take up, by the water content of the chips and by the method of application thereof in the performance of the impregnation.
• the temperature at which the impregnation with alkali is carried out must be low, for example, within the range of 30 C. to 40 C., and in any event below 100 C., in order to avoid discoloration of the chips.
• the reaction of the base with S0 is carried out directly in the digester under normally prevailing cooking conditions, namely in a vapor phase and at a temperature exceeding 100 C. and at corresponding superatmospheric pressure.
• the disintegration of the chips should take place immediately after the completion of the impregnation with alkali. In order to avoid non-desired discoloration, any storing for a longer period of the chips impregnated with the alkali must be avoided.
• EXAMPLE Pine chips are treated with steam at atmospheric pressure for less than five minutes and impregnated with NaOH in proportion corresponding to about 1.5 percent Na 0 calculated on a basis of the weight of the dry substance of the chips.
• the steamed chips are compressed in a screw press, as disclosed, for example, in the copending patent application referred to above. Thereupon the chips are allowed to expand in a soltuion of NaOH having a concentration of 3.5 percent.
• the chips from which excess of free impregnating liquid has been removed are sluiced continuously into a pressure vessel, the interior of which is maintained at a vapor pressure of 8 atmospheres above normal, and at a temperature of about C. by direct introduction of steam.
• free gaseous S0 is supplied to the pressure vessel in such quantity that an excess of free S0 is maintained in the steam.
• the chips are heated for 1 to 2 minutes in the acid steam atmosphere and immediately thereafter defibrated under the pressure and temperature conditions prevailing in the pressure vessel.
• the treated chips are removed by being passed through a sluice device into a zone of atmospheric pressure. Upon dilution with water to a concentration of percent the pulp was refined to a freeness of 290 CSF.
• the method of continuously producing chemomechanical pulp from lignocellulose containing material which comprises:

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Publications (1)

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ID=20266882

Family Applications (1)

Country Status (8)

Cited By (6)

Families Citing this family (2)

• 1964
  • 1964-05-20 GB GB20733/64A patent/GB1064567A/en not_active Expired
  • 1964-05-20 CH CH653664A patent/CH430421A/de unknown
  • 1964-05-20 DE DE19641517169 patent/DE1517169A1/de not_active Withdrawn
  • 1964-05-20 FI FI641078A patent/FI43032C/fi active
  • 1964-05-21 BE BE648248D patent/BE648248A/xx unknown
  • 1964-05-21 NL NL6405633A patent/NL6405633A/xx unknown
  • 1964-05-21 FR FR975349A patent/FR1395391A/fr not_active Expired
• 1967
  • 1967-12-29 US US694415A patent/US3558428A/en not_active Expired - Lifetime

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