US1787395A - Method for bleaching cellulose of any kind - Google Patents
Method for bleaching cellulose of any kind Download PDFInfo
- Publication number
- US1787395A US1787395A US327458A US32745828A US1787395A US 1787395 A US1787395 A US 1787395A US 327458 A US327458 A US 327458A US 32745828 A US32745828 A US 32745828A US 1787395 A US1787395 A US 1787395A
- Authority
- US
- United States
- Prior art keywords
- bleaching
- cellulose
- chlorine
- bleached
- necessary
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229920002678 cellulose Polymers 0.000 title description 41
- 239000001913 cellulose Substances 0.000 title description 41
- 238000004061 bleaching Methods 0.000 title description 40
- 238000000034 method Methods 0.000 title description 17
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 26
- 239000000460 chlorine Substances 0.000 description 26
- 229910052801 chlorine Inorganic materials 0.000 description 26
- 239000007864 aqueous solution Substances 0.000 description 14
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical class Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 11
- 238000005406 washing Methods 0.000 description 9
- 229910052783 alkali metal Inorganic materials 0.000 description 8
- 150000001875 compounds Chemical class 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- -1 alkali-metal hypochlorites Chemical class 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000003960 organic solvent Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000011282 treatment Methods 0.000 description 5
- 239000007844 bleaching agent Substances 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 239000003513 alkali Substances 0.000 description 3
- 150000001340 alkali metals Chemical class 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- ZKQDCIXGCQPQNV-UHFFFAOYSA-N Calcium hypochlorite Chemical compound [Ca+2].Cl[O-].Cl[O-] ZKQDCIXGCQPQNV-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical class OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- 229910052910 alkali metal silicate Inorganic materials 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- SYXUBXTYGFJFEH-UHFFFAOYSA-N oat triterpenoid saponin Chemical compound CNC1=CC=CC=C1C(=O)OC1C(C=O)(C)CC2C3(C(O3)CC3C4(CCC5C(C)(CO)C(OC6C(C(O)C(OC7C(C(O)C(O)C(CO)O7)O)CO6)OC6C(C(O)C(O)C(CO)O6)O)CCC53C)C)C4(C)CC(O)C2(C)C1 SYXUBXTYGFJFEH-UHFFFAOYSA-N 0.000 description 1
- 239000012476 oxidizable substance Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
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
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S162/00—Paper making and fiber liberation
- Y10S162/05—Alpha cellulose
Definitions
- Aqueous solutions of alkali-metal hypochlorites or bleaching powder are the usual bleaching agents for bleaching cellulose. It
- This saving of chlorine is due to the fact that a certain amount of oxidizable substances, liberated by the pre-bleaching process are removed by the intermediate washing process.
- the amount of chlorine used in the pre-bleaching can be still further substantially limited if the material to be bleached is washed with dilute alkalies such as sodium hydroxide, milk of lime and the like, beforethc chlorine treatment, whereby at the same time it is possible to avoid coloration of the fiber under the influence of the chlorine, which coloration would require the use of an increased amount of chlorine for its removal.
- dilute alkalies such as sodium hydroxide, milk of lime and the like
- the action of the dilute alkali solutions can be assisted by the addition of 02(- idizing agents.
- bleaching powder for example, or alkali metal sulfites or wetting agents such as soap, saponine. organic solvents and the like, or by the addition of several of these agents.
- Example Partially concentrated pulp is digested with a solution of alkali-metal or earth-alkalimetal hydroxide at temperatures between 10 and 80 C.
- the pulp concentration may be from 1 to 25% ;-the amount of alkaline reacting substances present maybe calculated as sodium hydroxide, 0.2 to 2% by weight of the
- the cellulose obtained is then treated, preferably in a closed vessel, with a measured amountof aqueous solution of chlorine, containing about 70 to 90% of the total chlorine necessary for bleaching.
- the concentratioi'i of the cellulose may be 120% in this treat ment. In about tol hour and at a temper: ature of between 5 to 20 C. the chlorine present is completely consumed.
- this preliminary bleachi g step is finished, the treated cellulose mass is at once, or better after a thorough washing with water, digested-in the same manner with alkaline reacting washing liquids as described above and washed with water.
- the pre-bleached cellulose mass thus obtained is partially concentrated and finished by bleaching it in the known manner with neutral or alkaline reacting hypochlorite solutions.
- This after-bleaching step may be accelerated, by the addition of inorganic or organic salts of catalytic metals, such as copper,
- a method for bleaching cellulose of any klnd which consists in digesting the cellulose to be bleached with diluted aqueous solutions of alkaline reacting compounds containing an oxidizing agent, an alkali-metal sulfite, a moistening agent and an organic solvent, subjecting the digested cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine in a measured.
- a method for bleaching cellulose of any kind which consists in digesting the cellulose to be bleached with diluted aqueous solutions of alkaline reacting compounds, subjecting the digested cellulose to a preIiminary bleaching with an aqueous solution of gaseous chlorine-in a measured amount less than the total necessary for complete bleaching, digesting the pre-bleached cellulose with diluted aqueous solutions of alkaline reacting compounds and subjecting the digested cellulose to an after-bleaching with hypochlorites.
- a method for bleaching cellulose of any kind which consists in digesting the cellulose to be bleached with diluted aqueous solutions of alkaline reacting compounds, subjecting the digested cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine in a measured amount less than the total necessary for complete bleaching, digesting the pre-bleached cellulose with diluted aqueous solutions oFalkaline reacting compounds containing an "oxidizing agent, an alkali-metal sulfite, a moistening agent and an organic solvent and subjecting the digested cellulose toan after-bleaching with hypochlorites.
- a method for bleaching cellulose of any kind which consists in digesting the cellulose mass to be bleached with diluted aqueous solutions of alkaline reacting compounds containing an oxidizing agent, an alkalimetal sulfite, a moistening agent, and an organic solvent, washing the digested cellulose with water,subjecting the washed cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine containing about -9()% of the chlorine necessary for complete bleaching and small amounts of salts of metals catalyzing the decomposition of hypochlorites, washing the pre-bleached cellulose with water, digesting the washed cellulose with diluted aqueous solutions of alkaline reacting compounds containing an oxidizing agent, an alkali-metal sulfite, a
Description
Patented Dec. 30, 1930 UNITED STATES PATENT OFFICE LADISLAV RYS, OF RUZOMBEROK, CZECHOSLOVAKIA METHOD FOR BLEACHING CELLULOSE OF ANY KIND No Drawing. Application filed December 20, 1928, Serial No. 327,458, and in Czechoslovakia December This invention relates to a' method for bleaching cellulose of any kind.
Aqueous solutions of alkali-metal hypochlorites or bleaching powder are the usual bleaching agents for bleaching cellulose. It
1 is known in the art, to subdivide the bleachis added at once to the cellulose to be bleached.
This saving of chlorine is due to the fact that a certain amount of oxidizable substances, liberated by the pre-bleaching process are removed by the intermediate washing process.
It is further known, to improve the bleaching process by using cellulose concentrations. of 15 to 24% instead of 5 8% as formerly, thereby increasing the rate of reaction during the bleaching process, avoiding heating of 25 the reaction mixture and reducing the amount of chlorine necessary. The disadvantage of a bleaching process with high cellulose concentration is, however, to,be seen in the fact, that the mixing of the viscous cellulose with the bleaching liquor is somewhat troublesome.
It is also known to bleach cellulose,'which if necessary has been subjected to a preliminary treatment with alkali metal or alkaline earth metal hydroxides or with alkali metal sulfitcs or bisulfites, by treatment with chlorine, repeated if necessary, before or after the bleaching process with alkaline peroxides with the addition of alkali metal silicates. It is also known to subject material, which has 40 been first bleached in the usual way, for'ex ample. with alkali hypochlorites, to a subsequent bleaching, repeated, if necessary, with chlorine. 7
However, these processes involve intensive treatment with considerable amounts of chlorine and for this reason injury to the material treated cannot be avoided even though the excess chlorine remaining in the material is removed by subsequenttreatment with sodium hyposulfite. for example. Furthermore, the cost of the comparatively large amount of chlorine used in these processes makes them expensive.
I have found that excellent results are obtained if, in the prebleaching with chlorine, the chlorine is used in the gaseous form or as chlorine water only in an amount up to about 90% of the total amount necessary for complete bleaching and it the bleaching is then completed by applying the remainder of the necessary chlorine in the form of hypochlorite. In this manner, the bleaching can be performed with greatest simplicity, with greatest sparing of the fibers of the material treated and with great saving of materials.
I have found further that the amount of chlorine used in the pre-bleaching can be still further substantially limited if the material to be bleached is washed with dilute alkalies such as sodium hydroxide, milk of lime and the like, beforethc chlorine treatment, whereby at the same time it is possible to avoid coloration of the fiber under the influence of the chlorine, which coloration would require the use of an increased amount of chlorine for its removal. In this washing operation the action of the dilute alkali solutions can be assisted by the addition of 02(- idizing agents. such as bleaching powder, for example, or alkali metal sulfites or wetting agents such as soap, saponine. organic solvents and the like, or by the addition of several of these agents.
As compared to bleaching processes heretofore known in the art, all varieties of cellulose may be bleached by the process of the present invention with a saving of 25-30); of active chlorine, and a product of better color and higher chemical purity is obtained. As the process may be carried out in the cold in a short time, it may be used as a continu ous process without it being necessary to work with high cellulose concentrations.
Example Partially concentrated pulp is digested with a solution of alkali-metal or earth-alkalimetal hydroxide at temperatures between 10 and 80 C. The pulp concentration may be from 1 to 25% ;-the amount of alkaline reacting substances present maybe calculated as sodium hydroxide, 0.2 to 2% by weight of the When the digestion is finished, the liquid is drawn off and the pulp is washed with water. The cellulose obtained is then treated, preferably in a closed vessel, with a measured amountof aqueous solution of chlorine, containing about 70 to 90% of the total chlorine necessary for bleaching. The concentratioi'i of the cellulose may be 120% in this treat ment. In about tol hour and at a temper: ature of between 5 to 20 C. the chlorine present is completely consumed.
l/Vhen this preliminary bleachi g step is finished, the treated cellulose mass is at once, or better after a thorough washing with water, digested-in the same manner with alkaline reacting washing liquids as described above and washed with water.
The pre-bleached cellulose mass thus obtained is partially concentrated and finished by bleaching it in the known manner with neutral or alkaline reacting hypochlorite solutions.
This after-bleaching step may be accelerated, by the addition of inorganic or organic salts of catalytic metals, such as copper,
. nickel, cobalt and the like, along with the chlorine water in the preliminary bleaching step. Because of the prevailing weakly acid reaction these salts remain in solution with- .lutionsof alkaline reacting compounds, subjecting the digested cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine in a measured amount less than the total necessary for compleie bleaching, washing the pre-bleached cellulose and subjecting the washed cellulose to an aften bleaching with hypochlorites. l 2. A method for bleaching cellulose of any klnd which consists in digesting the cellulose to be bleached with diluted aqueous solutions of alkaline reacting compounds containing an oxidizing agent, an alkali-metal sulfite, a moistening agent and an organic solvent, subjecting the digested cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine in a measured.
amount less than the t'otalwnecessary for complete bleaching, washing the pie-bleached .cellulose and subjecting the washed cellulose to an after-bleaching with hypochlorites.
3. A method for bleaching cellulose of any kind which consists in digesting the cellulose to be bleached with diluted aqueous solutions of alkaline reacting compounds, subjecting the digested cellulose to a preIiminary bleaching with an aqueous solution of gaseous chlorine-in a measured amount less than the total necessary for complete bleaching, digesting the pre-bleached cellulose with diluted aqueous solutions of alkaline reacting compounds and subjecting the digested cellulose to an after-bleaching with hypochlorites.
4. A method for bleaching cellulose of any kind which consists in digesting the cellulose to be bleached with diluted aqueous solutions of alkaline reacting compounds, subjecting the digested cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine in a measured amount less than the total necessary for complete bleaching, digesting the pre-bleached cellulose with diluted aqueous solutions oFalkaline reacting compounds containing an "oxidizing agent, an alkali-metal sulfite, a moistening agent and an organic solvent and subjecting the digested cellulose toan after-bleaching with hypochlorites.
5. A method for bleaching cellulose of any kind which consists in digesting the cellulose mass to be bleached with diluted aqueous solutions of alkaline reacting compounds containing an oxidizing agent, an alkalimetal sulfite, a moistening agent, and an organic solvent, washing the digested cellulose with water,subjecting the washed cellulose to a preliminary bleaching with an aqueous solution of gaseous chlorine containing about -9()% of the chlorine necessary for complete bleaching and small amounts of salts of metals catalyzing the decomposition of hypochlorites, washing the pre-bleached cellulose with water, digesting the washed cellulose with diluted aqueous solutions of alkaline reacting compounds containing an oxidizing agent, an alkali-metal sulfite, a
moistening agent and an organic solvent,
washing the digested cellulose with water and subjecting the washed cellulose to an after-bleaching with solutions of hypochlorites containing the remaining amount of active chlorine necessary for bleaching.
In testimony whereof I aflix 'my signature. LADISLAV R YS,
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CS1787395X | 1927-12-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US1787395A true US1787395A (en) | 1930-12-30 |
Family
ID=5458443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US327458A Expired - Lifetime US1787395A (en) | 1927-12-19 | 1928-12-20 | Method for bleaching cellulose of any kind |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US1787395A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2779656A (en) * | 1953-06-16 | 1957-01-29 | Du Pont | Bleaching of kraft pulp |
| US3622444A (en) * | 1969-04-14 | 1971-11-23 | Canadian Ind | Pulp bleaching process |
-
1928
- 1928-12-20 US US327458A patent/US1787395A/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2779656A (en) * | 1953-06-16 | 1957-01-29 | Du Pont | Bleaching of kraft pulp |
| US3622444A (en) * | 1969-04-14 | 1971-11-23 | Canadian Ind | Pulp bleaching process |
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