Patent US4106979A successfully refreshed from Google Patents.
US4106979A
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Preparation of paper pulps from dicotyledonous plants
Assignee: Consorzio Fabocart SpA
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Filing: 1977-03-21
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Granted: 1978-08-15
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Expires: 1997-03-21
Abstract
Abstract Paper pulp is prepared from dicotyledonous plants by stirring said plants in an alkaline solution in the presence of a surfactant and stain inhibiting agent to obtain a stock containing a woody core fraction and a bark fraction containing bast fibers, separating said fractions and then cooking and bleaching the bark fraction in an alkaline solution containing an oxidizing agent and an alkyl sulfate surfactant.
Inventors
- 👤 Guglielmo Ruffini
- 👤 Erio Pezzotti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 07:11
CPC Classifications
D; D21; D21B; D21B1/00; D21C; D21C1/00; D21C3/00; D21C3/22; D21C3/222
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
139 words
A process for the preparation of pulps for paper from dicotyledonous plants, comprising the steps of: stirring in a pulper, the dicotyledonous plants in an alkaline solution in the presence of a surfactant and at least one stain inhibiting agent selected from the group consisting of peroxides and sodium hypochlorite, which agent prevents staining of the plant fibers in alkaline media by blocking the chromophoric groups of the dicotyledonous plants, in order to obtain a stock containing a both woody core fraction and a bark fraction containing bast fibers; dividing said stock into a woody core fraction and a bark fiber fraction; and then subsequently cooking and bleaching said bark fraction under atmospheric pressure in an alkaline solution containing an alkyl sulfate surfactant and an oxidizing agent selected from the group consisting of hydrogen peroxide and tertiary butyl hydroperoxide.
Claim 2
Dependent Claim
139 words
A process for the preparation of pulps for paper from dicotyledonous plants, comprising the steps of: stirring in a pulper, the dicotyledonous plants in an alkaline solution in the presence of a surfactant and at least one stain inhibiting agent selected from the group consisting of peroxides and sodium hypochlorite, which agent prevents staining of the plant fibers in alkaline media by blocking the chromophoric groups of the dicotyledonous plants, in order to obtain a stock containing a both woody core fraction and a bark fraction containing bast fibers; dividing said stock into a woody core fraction and a bark fiber fraction; and then subsequently cooking and bleaching said bark fraction under atmospheric pressure in an alkaline solution containing an alkyl sulfate surfactant and an oxidizing agent selected from the group consisting of hydrogen peroxide and tertiary butyl hydroperoxide.
Claim 3
Dependent Claim
21 words
A process according to claim 1, wherein before cooking and bleaching, the bark fraction is treated with active chlorine generating agents.
Claim 4
Dependent Claim
33 words
A process according to claim 2, wherein the treatment with the active chlorine generating agents is performed with 2-10% active chlorine at a temperature between room temperature and 80° C for 30-120 minutes.
Claim 5
Dependent Claim
17 words
A process according to claim 1, wherein the temperature of the alkaline solution is about 75° C.
Claim 6
Dependent Claim
38 words
A process according to claim 1, wherein the alkaline solution employed in said stirring step is obtained by dissolving in water an alkaline agent selected from the group consisting of sodium hydroxide, sodium sulfite and a mixture thereof.
Claim 7
Dependent Claim
54 words
A process according to claim 1, wherein the cooking and bleaching of the bark fraction is carried out at 50°-90° C for 30-120 minutes with 2-6% peroxide calculated as H 2 O 2 , 5-20% of alkali and 0.1-0.5% of alkyl sulfate surfactant, all percentages being based on the weight of dry raw material.
Claim 8
Dependent Claim
43 words
A process according to claim 1, wherein after the cooking and bleaching step the prepared pulp is washed and acidified to a pH of 5-6 with an aqueous solution of a member selected from the group consisting of sulphur dioxide and oxalic acid.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-08-14 | 1982-02-13 | 1982-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-08-14 | 1986-02-13 | 1986-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-08-14 | 1990-02-13 | 1990-08-15 | $7700.00 | Window Closed / Lapsed |