Nonsulfur chemimechanical pulping process
First Claim
1. A process for pulping woody materials comprising:
- providing a pulping solution containing a dilute mixture of a lower alkanolamine and ammonium hydroxide in water;
providing a heated vessel;
admitting a predetermined quantity of chips and solution to said vessel;
impregnating said chips in said solution and digesting said chips under conditions of temperature and pressure effective to initiate a lignin depolymerization reaction in said chips for a predetermined period of time;
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Accused Products
Abstract
A nonsulfur chemimechanical pulping process for producing pulp from woody materials is disclosed. The process is particularly suited for producing corrugating medium pulp from hardwood chips although the process can be adapted to production of other types of pulp and can use other types of woody materials. The process comprises impregnation and dilution of the chips in a dilute aqueous pulping solution of a lower alkanolamine catalyzed with ammonium hydroxide. The preferred alkanolamine is monoethanolamine present in a weight ratio to ammonium hydroxide of about 1 part to 1 part or less to 1 part to 3 parts or more. The pulping solution may be repeatedly reused and the process of this invention does not produce environmentally objectionable by-products.
24 Citations
18 Claims
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1. A process for pulping woody materials comprising:
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providing a pulping solution containing a dilute mixture of a lower alkanolamine and ammonium hydroxide in water; providing a heated vessel; admitting a predetermined quantity of chips and solution to said vessel; impregnating said chips in said solution and digesting said chips under conditions of temperature and pressure effective to initiate a lignin depolymerization reaction in said chips for a predetermined period of time; - View Dependent Claims (3, 5, 6, 7, 9, 11, 13, 15, 16, 17, 18)
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- 2. refining said chips to produce said pulp and separating the used solution from the pulp.
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8. A process for producing corrugating medium pulp from hardwood chips comprising:
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providing a pulping solution containing a dilute aqueous mixture of a lower alkanolamine and ammonium hydroxide; providing a heated vessel; admitting a predetermined quantity of said chips to said vessel; heating said solution; subsequently digesting said chips in said vessel under conditions of temperature and pressure effective to initiate a lignin depolymerization reaction in said chips for a predetermined period of time; refining said chips to produce said pulp; and separating the used solution from the pulp for chemical reactant recovery. - View Dependent Claims (10, 12)
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14. A continuous process for producing corrugating medium pulp from hardwood chips comprising:
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providing a pulping solution of a dilute aqueous mixture of 1 part of a lower alkanolamine and less than 3 parts ammonium hydroxide; providing a heated vessel; admitting a predetermined quantity of chips to said vessel; heating said solution; subsequently digesting said chips in said vessel under conditions of temperature and pressure effective to initiate alignin depolymerization reaction in said chips for a predetermined period of time; refining said chips to produce said pulp; and separating the used solution from the pulp for chemical reactant recovery.
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Specification