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US4618400A
Expired / Lapsed
US
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Wastepaper deinking process
Assignee: HELLER FINANCIAL Inc AS AGENT
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Filing: 1986-01-10
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Granted: 1986-10-21
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Expires: 2006-01-10
Abstract
Abstract A method for the deinking of wastepaper which comprises converting the wastepaper to a pulp, contacting the pulp with an aqueous medium of alkaline pH containing between about 0.2 and 2 percent by weight, calculated on dry weight of the pulp, of a deinking agent which is one or a mixture of certain thiol ethoxylate compounds, and treating the resulting pulp-containing medium to remove suspended or dispersed ink. The use of a thiol ethoxylate deinking agent offers a high level of performance in such a deinking process, both from the standpoint of the overall brightness and dirt count of paper prepared from the deinked pulp. In certain specific embodiments, the invention further comprises a step for treating thiol ethoxylate containing process streams and effluents to convert the surface active deinking agent to low-foaming sulfonyl derivatives, or to degrade the deinking agent to non-surface-active matter.
Inventors
- 👤 Donald L. Wood
- 👤 Herbert E. Fried
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:58
CPC Classifications
D; D21; D21C; D21C5/00; D21C5/02; D21C5/025; D21C5/027; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/64
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
154 words
A process for the deinking of wastepaper stocks which comprises steps for a. converting the wastepaper to a pulp, b. contacting the pulp with an aqueous medium of alkaline pH containing between about 0.2 and 2 percent by weight, calculated on dry weight of the pulp, of a deinking agent which is one or a mixture of thiol ethoxylate compounds of the formula RS--CH.sub.2 CH.sub.2 O).sub.n H, wherein R represents a C 9 to C 18 alkyl group and n has an average value between about 3 and 20, c. treating the resulting pulp-containing medium to remove suspended or dispersed ink therefrom, and d. treating the pulp-containing aqueous medium, subsequent to step c, with an oxidizing agent at a temperature of at least about 75° C. and at a pH of at least about 12.0 to bleach the pulp and to convert all or part of the thiol ethoxylate deinking agent to non-surface-active matter.
Claim 2
Dependent Claim
154 words
A process for the deinking of wastepaper stocks which comprises steps for a. converting the wastepaper to a pulp, b. contacting the pulp with an aqueous medium of alkaline pH containing between about 0.2 and 2 percent by weight, calculated on dry weight of the pulp, of a deinking agent which is one or a mixture of thiol ethoxylate compounds of the formula RS--CH.sub.2 CH.sub.2 O).sub.n H, wherein R represents a C 9 to C 18 alkyl group and n has an average value between about 3 and 20, c. treating the resulting pulp-containing medium to remove suspended or dispersed ink therefrom, and d. treating the pulp-containing aqueous medium, subsequent to step c, with an oxidizing agent at a temperature of at least about 75° C. and at a pH of at least about 12.0 to bleach the pulp and to convert all or part of the thiol ethoxylate deinking agent to non-surface-active matter.
Claim 3
Dependent Claim
22 words
A process according to claim 1, wherein the temperature is at least about 85° C. and the pH at least about 13.0.
Claim 4
Dependent Claim
29 words
A process according to claim 1, wherein the oxidizing agent is selected from the group consisting of alkali metal hypochlorites, hydrogen peroxide, organic and inorganic peracids and chlorine dioxide.
Claim 5
Dependent Claim
29 words
A process according to claim 2, wherein the oxidizing agent is selected from the group consisting of alkali metal hypochlorites, hydrogen peroxide, organic and inorganic peracids and chlorine dioxide.
Claim 6
Dependent Claim
145 words
A process for the deinking of wastepaper stocks which comprises steps for a. converting the wastepaper to a pulp, b. contacting the pulp with an aqueous medium of alkaline pH containing between about 0.2 and 2 percent by weight, calculated on dry weight of the pulp, of a deinking agent which is one or a mixture of thiol ethoxylate compounds of the formula RS--CH.sub.2 CH.sub.2 O).sub.n H, wherein R represents a C 9 to C 18 alkyl group and n has an average value between about 3 and 20, c. treating the resulting pulp-containing medium to remove suspended or dispersed ink therefrom, and d. treating process effluent wastewater containing deinking agent with an oxidizing agent at a temperature of at least 75° C. and at a pH of at least about 12 for conversion of all or part of the deinking agent to non-surface-active matter.
Claim 7
Dependent Claim
145 words
A process for the deinking of wastepaper stocks which comprises steps for a. converting the wastepaper to a pulp, b. contacting the pulp with an aqueous medium of alkaline pH containing between about 0.2 and 2 percent by weight, calculated on dry weight of the pulp, of a deinking agent which is one or a mixture of thiol ethoxylate compounds of the formula RS--CH.sub.2 CH.sub.2 O).sub.n H, wherein R represents a C 9 to C 18 alkyl group and n has an average value between about 3 and 20, c. treating the resulting pulp-containing medium to remove suspended or dispersed ink therefrom, and d. treating process effluent wastewater containing deinking agent with an oxidizing agent at a temperature of at least 75° C. and at a pH of at least about 12 for conversion of all or part of the deinking agent to non-surface-active matter.
Claim 8
Dependent Claim
21 words
The process of claim 5, wherein the temperature is at least about 85° C. and the pH at least about 13.0.
Claim 9
Dependent Claim
29 words
A process according to claim 5, wherein the oxidizing agent is selected from the group consisting of alkali metal hypochlorites, hydrogen peroxide, organic and inorganic peracids and chlorine dioxide.
Claim 10
Dependent Claim
29 words
A process according to claim 6, wherein the oxidizing agent is selected from the group consisting of alkali metal hypochlorites, hydrogen peroxide, organic and inorganic peracids and chlorine dioxide.
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