US3551410A - Method of increasing the water-retentivity of cellulose fibers and the product produced thereby - Google Patents
Method of increasing the water-retentivity of cellulose fibers and the product produced thereby Download PDFInfo
- Publication number
- US3551410A US3551410A US811221A US3551410DA US3551410A US 3551410 A US3551410 A US 3551410A US 811221 A US811221 A US 811221A US 3551410D A US3551410D A US 3551410DA US 3551410 A US3551410 A US 3551410A
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- US
- United States
- Prior art keywords
- water
- retentivity
- solution
- salt
- carboxy cellulose
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- 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.)
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
- C08B15/02—Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
- C08B15/04—Carboxycellulose, e.g. prepared by oxidation with nitrogen dioxide
Definitions
- the present invention relates to a process for increasing the water-retentitivity of cellulose fibers, and to the products produced by such process. More particularly, it relates to a process for increasing the water-retentivity of carboxy cellulose fibers, and the products produced by such process.
- cellulose-containing materials such as wood pulp, cotton, cotton linters or rayon have the ability to retain water within and between their fibers.
- the amount of water retained may equal or exceed the weight of the fibers.
- the fiber mass is wet to the touch and liquid water can be squeezed out by the application of pressure.
- cellulosic-containing starting materials can be employed.
- exemplary of such cellulosic materials are wood pulps, such as kraft pulp or sulfite pulp,
- the cellulosic starting material is reacted with nitrogen dioxide under process conditions well known in the art. It is known that if the cellulosic starting material is fully reacted, a 6-carboxy cellulose having a carboxyl content of about 25% is obtained. This indicates that the 6-hydroxy group on the anhydroglucose monomeric unit in the cellulose chain has been completely converted to 6-carboxyl. Improved water-retentivity is also exhibited at a carboxyl content as low as 3%. However, it is preferred for the purposes of the present invention that the reaction be carried to a point where only from about 10% to about 15% carboxyl content is obtained.
- the 6-carboxy cellulose is then immersed or soaked in an aqueous salt solution.
- the aqueous salt solution consists of a mixture of water-soluble salts, buffering at pH values between about 6.0 and about 7.5.
- the initial pH of the salt solution which is the pH before the addition of 6-car-boxy cellulose, is 7.
- ApH the change in pH
- the change in pH which is due to the ion exchange capacity of the carboxy cellulose, should preferably be between about 0 and about 0.5 pH units and even more preferably from about 0 to about 0.1 pH unit.
- the concentration of the water-soluble salt mixtures can be from about 1 gram per liter of solution up to the point where the solution becomes saturated. Concentrations of from about 20 grams to about grams per liter of solution are preferred, and, it is especially preferred to employ a concentration of about 40 grams of salt mixture per liter of solution. A concentration of approximately 40 grams per liter of solution, it has been found, results in a fiber which is neither stiff nor harsh;
- any mixture of salts may be used provided their buffering action results in an initial pH for the aqueous salt solution of from about 6.0 to about 7.5. It is also important that the final pH, namely, the pH of the solution just prior to filtration of the salt treated 6-carboxy cellulose fibers, be within the range of from about 0 to about 0.5 pH units of the initial pH of the salt solution alone.
- Exemplary of the salt solutions containing mixtures of salts conforming to the foregoing requirements, but not limited thereto, are: ammonium bisulfite-ammonium sulfite, ammonium dihydrogen phosphate-diammouium hydrogen phosphate, potassium monohydrogen phosphatepotassium dihydrogen phosphate, potassium bisulfitepotassium sulfite, sodium dihydrogen phosphate-disodium monohydrogen phosphate and sodium bisulfite-sodium sulfite.
- the preferred salt mixture from the point of view of economy, availability and practicality is sodium bisulfite-sodium sulfite.
- the 6-carboxy cellulose can be soaked in the aqueous salt solution for periods of time ranging from less than one hour up to and including 25 hours and more. It is quite interesting to note that 6-carboxy cellulose exhibits marked improvement in its ability to retain water almost instantaneously upon immersion. It has also been found that the longer the soaking or immersion period, the greater the increase in percent water-retentivity exhibited by the 6-carboxy cellulose. Thus, the upper time limit is governed largely by practical economic considerations.
- the temperature at which the soaking is conducted can be within the range of from about 0 C. to about 100 C. It appears that, with increasing temperature, the ability of the salt soaked 6-carboxy cellulose to retain water increases.
- the salt treated 6-carboxy cellulose prepared in accordance with the present invention, is separated from the salt solution by filtration.
- the resulting fibers are then washed and dried, although drying is not an absolute necessity.
- the resulting fibers can then be used alone or slurried and blended with either synthetic or naturally occurring fibers to produce a highly water-retentive product. It is of interest to note that the salt treated 6-carboxy cellulose fibers retain their high degree of water-retentivity even after they have been washed with water.
- EXAMPLE I 440 grams of flocked pulp (400 g. bone dry weight) was charged into a 22 liter round-bottomed flask. The flask was placed on its side on rollers and rotated at 30 r.p.m. A shallow water bath covered the rollers so that /3 of the exterior surface of the flask was in contact with the water. The water temperature was controlled at 25 C. Nitrogen dioxide gas was passed for 6% hours into the flask through a A" diameter stainless steel tube inserted through the neck of the flask and extending to within about 1 cm. from the bottom. A Teflon cover containing a hole for the stainless steel tube was placed in the neck of the flask. The gas flow was adjusted so an excess of the brown N0 gas slowly escaped through the hole in the cap.
- the flask was purged for 10 minutes with a stream of air passed through the stainless steel tube. Then the flask was removed from the rollers, the product was slurried in water, drained on a large Buchner funnel and the product was reslurried in methanol. The methanol slurry was filtered again, the product was washed four times with water and dried overnight in a stream of air at 40 C.
- the time of contact with N0 gas may be lengthened to obtain a higher carboxyl level and shortened to obtain a lower carboxyl level.
- EXAMPLE II In each of the experiments listed below in Table 1, 2.0 grams of air dried 6-carboxy cellulose fiber, prepared in accordance with Example I, was slurried in 500 mls. of a salt solution. Each of the salt solutions contained a sodium bisulfite-sodium sulfite mixture. The composition of the salt mixture and the percentage water retention are indicated in Table 1. After soaking 18 hours the fiber slurry was stirred using an Osterizer stirrer at maximum speed for forty seconds. The stirring gives a more uniform slurry. The slurry was filtered using a Whatman No. 4 filter paper in a Biichner funnel with an OD. of 67 mm.
- the fiber pad in the filter was pressed until the fibers and the adhering solution weighed from about 8 to about 11 grams. Weight was determined accurately and the funnel was placed in a vacuum oven without removing the fiber pad. After drying overnight at a temperature of 50 C. and 500 mm. of vacuum, the funnel was placed on a Biichner flask which was connected to a 150 mm. vacuum source. mls. of water containing 0.1% of an anionic surfactant was poured over the surface of the pad. Water was allowed to drain through the pad until the pad surface was free of pools of liquid. Then a glass plate was placed over the funnel and the vacuum was continued for another two minutes. The pad was then removed from the funnel, the filter paper carefully stripped off and the wet pad was weighed accurately. The pad was dried C., atmospheric pressure) and reweighed. The percentage water retention was calculated in accordance with the formula appearing below.
- EXAMPLE IV In each of the experiments listed below in Table 3, 2 grams of 6-carboxy cellulose, having a carboxyl content of 12%, was soaked in a sodium bisulfite-sodium sulfite solution for varying lengths of time at room temperature. Each of the solutions contained 10 grams of sodium bisulfite and 30 grams of sodium sulfite per liter of solution. The procedure described in Example III was then employed and the percent water-retentivity was then calculated in accordance with the formula of Example II.
- Example VI A sample of 2 grams of 6-carboxy cellulose was treated as per Example VI. It was dried after draining the liquor. The dried sample was mixed with Cellate, which is an unoxidized, untreated kraft pulp produced by Canadian International Paper Co., in diiferent proportions and the mixtures were reslurried in water. Hand sheets were formed from these slurries. The hand sheets were pressed under 8.5 lbs/sq. inch pressure by an hydraulic press and then dried. The percent water retention was calculated in accordance with the formula in Example II.
- Cellate which is an unoxidized, untreated kraft pulp produced by Canadian International Paper Co.
- EXAMPLE VIII Rayon staple fiber had a water-retentivity of 167% by the test outlined in Example III. After conversion to carboxylated rayon (12.9% carboxyl) and soaking for 18 hours in a solution containing 30 g./l. Na SO and 10 g./l. NaHSO the treated rayon has a water-retentivity of 860%.
- a process for increasing the water-retentivity of 6-carboxy cellulose having a carboxyl content of from about 3% to about 25% by weight which comprises soaking said 6-carboxy cellulose in an aqueous solution comprising a mixture of water-soluble salts bulfering at an initial pH between about 6.0 and about 7.5, said mixture of water-soluble salts being selected from the group consisting of ammonium bisulfite-ammonium sulfite, ammonium dihydrogen phosphate-diammonium hydrogen phosphate, dipotassium monohydrogen phosphate-potassium dihydrogen phosphate, potassium bisulfite-potassium sulfite, sodium dihydrogen phosphate-disodium monohydrogen phosphate, and sodium bisulfite-sodium. sulfite, recovering the salt-treated 6-carboxy cellulose from the aqueous salt solution wherein the final pH is within the range of from about 0 to about 0.5 pH units of the initial pH of the solution.
- a cellulosic material having a high degree of waterretentivity which comprises a water-insoluble salt of 6-carboxy cellulose having a carboxyl content of from about 3% to about 25% by weight and having from about 75% or more of said carboxyl groups salt substituted, said 6-carboxy cellulose having been soaked in an equeous solution comprising a mixture of watersoluble salts buffering at an initial pH of from about 6.0 to about 7.5 and wherein the final pH of the aqueous salt solution is within the range of from about '0 to about 0.5 pH units of the initial pH of the solution, said mixture of water-soluble salts being selected from the group consisting of ammonium bisulfite-ammonium sulfite, ammonium dihydrogen phosphate-diammonium hydrogen phosphate, dipotassium monohydrogen phosphate-potassium dihydrogen phosphate, potassium bisulfite-potassium sulfite, sodium dihydrogen phosphatedisodium monohydrogen phosphat
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US81122169A | 1969-03-27 | 1969-03-27 |
Publications (1)
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US3551410A true US3551410A (en) | 1970-12-29 |
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US811221A Expired - Lifetime US3551410A (en) | 1969-03-27 | 1969-03-27 | Method of increasing the water-retentivity of cellulose fibers and the product produced thereby |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5082723A (en) * | 1989-09-27 | 1992-01-21 | Kimberly-Clark Corporation | Osmotically enhanced absorbent structures |
US5118390A (en) * | 1990-08-28 | 1992-06-02 | Kimberly-Clark Corporation | Densified tactile imaging paper |
US5247072A (en) * | 1991-10-25 | 1993-09-21 | Kimberly-Clark Corporation | Carboxyalkyl polysaccharides having improved absorbent properties and process for the preparation thereof |
US5550189A (en) * | 1992-04-17 | 1996-08-27 | Kimberly-Clark Corporation | Modified polysaccharides having improved absorbent properties and process for the preparation thereof |
US5651862A (en) * | 1991-08-13 | 1997-07-29 | Kimberly-Clark Worldwide, Inc. | Wet-formed absorbent composite |
US20030125683A1 (en) * | 2001-12-31 | 2003-07-03 | Reeves William G. | Durably hydrophilic, non-leaching coating for hydrophobic substances |
US20030143388A1 (en) * | 2001-12-31 | 2003-07-31 | Reeves William G. | Regenerated carbohydrate foam composition |
US20030155679A1 (en) * | 2001-12-31 | 2003-08-21 | Reeves William G. | Method of making regenerated carbohydrate foam compositions |
-
1969
- 1969-03-27 US US811221A patent/US3551410A/en not_active Expired - Lifetime
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5082723A (en) * | 1989-09-27 | 1992-01-21 | Kimberly-Clark Corporation | Osmotically enhanced absorbent structures |
US5118390A (en) * | 1990-08-28 | 1992-06-02 | Kimberly-Clark Corporation | Densified tactile imaging paper |
US5651862A (en) * | 1991-08-13 | 1997-07-29 | Kimberly-Clark Worldwide, Inc. | Wet-formed absorbent composite |
US5247072A (en) * | 1991-10-25 | 1993-09-21 | Kimberly-Clark Corporation | Carboxyalkyl polysaccharides having improved absorbent properties and process for the preparation thereof |
US5550189A (en) * | 1992-04-17 | 1996-08-27 | Kimberly-Clark Corporation | Modified polysaccharides having improved absorbent properties and process for the preparation thereof |
US20030125683A1 (en) * | 2001-12-31 | 2003-07-03 | Reeves William G. | Durably hydrophilic, non-leaching coating for hydrophobic substances |
US20030143388A1 (en) * | 2001-12-31 | 2003-07-31 | Reeves William G. | Regenerated carbohydrate foam composition |
US20030155679A1 (en) * | 2001-12-31 | 2003-08-21 | Reeves William G. | Method of making regenerated carbohydrate foam compositions |
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Legal Events
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AS | Assignment |
Owner name: CIP INC. Free format text: MERGER;ASSIGNORS:CANADIAN INTERNATIONAL PAPER COMPANY;PORTEMIAC PAPER CORPORATION;INTERNATIONAL PAPER SALES COMPANY INC.;AND OTHERS;REEL/FRAME:003933/0966 Effective date: 19811001 |
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AS | Assignment |
Owner name: CIP INC. (FORMERLY KNOWN AS CIP FOREST PRODUCTS IN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE DATE 07/26/85;ASSIGNOR:TALBERT INC.;REEL/FRAME:004606/0152 Effective date: 19860616 Owner name: CIP INC. (FORMERLY KNOWN AS CIP FOREST PRODUCTS IN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TALBERT INC.;REEL/FRAME:004606/0152 Effective date: 19860616 Owner name: CIP INC. Free format text: CHANGE OF NAME;ASSIGNOR:CIP FOREST PRODUCTS INC./PRODUITS FORESTIERS CIP INC.;REEL/FRAME:004592/0491 Effective date: 19850729 |
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Owner name: TABERT INC Free format text: CHANGE OF NAME;ASSIGNOR:CIP INC;REEL/FRAME:004697/0506 Effective date: 19861126 |