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Method for preparation of stabilized carboxylated cellulose

a technology cellulose, which is applied in the field of preparation of stabilized carboxylated cellulose, can solve the problems of poor reproduction of the tempo system, inability to obtain water soluble materials, and equivocality

Inactive Publication Date: 2003-03-20
WEYERHAEUSER CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0038] The suitability of lower cost market pulps is a significant advantage of the process. Market pulps are used for many products such as fine papers, diaper fluff, paper towels and tissues, etc. These pulps generally have about 86-88% .alpha.-cellulose and 12-14% hemicellulose whereas the high .alpha.-cellulose chemical or dissolving pulps have about 92-98% .alpha.-cellulose. By stable is meant minimum D.P. loss in alkaline environments, and very low self cross linking and color reversion. The method of the invention is particularly advantageous for treating secondary (or recycled) fibers. Bond strength of the sheeted carboxylated fibers is significantly improved over untreated recycled fiber.
[0064] It is a further object to provide a cellulose fiber having an enhanced carboxyl content at the fiber surface.

Problems solved by technology

Results with the TEMPO system were poorly reproduced and equivocal.
Using native celluloses or bleached wood pulp he was unable to obtain a water soluble material since he achieved only low amounts of conversion.

Method used

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  • Method for preparation of stabilized carboxylated cellulose
  • Method for preparation of stabilized carboxylated cellulose
  • Method for preparation of stabilized carboxylated cellulose

Examples

Experimental program
Comparison scheme
Effect test

example 2

Effect on Cellulose D.P. after Caro's Acid Oxidation

[0089] An oxidized cellulose sample was prepared in similar manner to that of Example 1 except that the pulp used was a never dried sample of northern mixed conifer bleached kraft furnish obtained from a Weyerhaeuser Company Grand Prairie, Alberta mill. The Caro's acid was prepared from K.sub.2S.sub.2O.sub.8 and 98% sulfuric acid and diluted with deionized water to give 60 mL of a 0.28% solution. This was further diluted with 60 mL of deionized water and adjusted to pH 7.5 with NaHCO.sub.3. The oxidation catalyst was prepared by dissolving 0.012 g of the 1,3-propanediol ketal of 2,2,6,6-tetramethyl-4-piperidone-1-oxyl in the Caro's acid solution. Then 51 g (12.5 g O.D.) was suspended in the basic Caro's acid solution and finally 0.25 g of NaBr was added and mixed well. The mixture was placed in a polyethylene bag and heated in a water bath for 15 minutes at 60.degree. C. The fiber was filtered off and washed well in deionized water...

example 3

Stabilization of Oxidized Cellulose using Caro's Acid Under Acidic Conditions

[0092] An additional sample of the never dried Alberta pulp was oxidized using 7,7,9,9-tetramethyl-1,4-dioxa-8-azaspiro[4.5]decane-2-methanol rather than TEMPO. This material is also designated as the glyceryl ketal of triacetoneamine. A 145 mg portion of the amine was dissolved in 250 g of 0.28% basic Caro's acid solution at pH 7.5. A slurry of 102 g never dried Grand Prairie kraft pulp (25 g O.D.) was then dispersed in the solution. The mixture was placed in a plastic bag and 500 mg NaBr was added and dispersed throughout the mixture. The bag was sealed and placed in a water bath at 60.degree. C. for 30 minutes. The oxidized cellulose was drained and thoroughly washed with deionized water. A small portion was retained for analysis and the remainder divided into two parts.

[0093] A first 30 g portion of the oxidized cellulose (8.0 g O.D.) was dispersed in 500 mL of Na.sub.2HPO.sub.4 / citric acid buffer solut...

example 4

1,3-Propanediol Ketal of Triacetone Amine Used to Generate its Oxammonium Salt In Situ

[0096] A Caro's acid stock solution was prepared using 200 g of 98% H.sub.2SO.sub.4 and 40 g of 70% H.sub.2O.sub.2. An 0.80 g portion of this was added to 100 g of deionized water and the pH raised to 7.5 with Na.sub.2CO.sub.3. The concentration of Caro's acid was 0.28% and of H.sub.2O.sub.2 0.02% by weight. Into this solution was dispersed 51 g (12.5 g O.D.) of the never dried Alberta pulp of Example 2. A catalyst solution was made by dissolving 0.0048 g of the 1,3-propanediol ketal of triacetoneamine and 0.250 g of NaBr in 50 g of a solution brought to pH 7.5 with NaHCO.sub.3. This was added to the cellulose slurry in Caro's acid solution and the mixture was placed in a polyethylene bag and immersed in a 60.degree. C. water bath for 15 minutes. After the initial oxidation the pulp was drained and washed and a small sample taken for analysis.

[0097] The oxidized cellulose was then dispersed in 500 ...

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Abstract

The invention is directed to a method of making a heat and light stable carboxylated cellulose fiber whose fiber strength and degree of polymerization is not significantly sacrificed. The method involves the use of a catalytic amount of a hindered cyclic oxammonium salt as a primary oxidant and a peracid and halide salt as a secondary oxidant in an aqueous environment. The oxammonium compounds may be formed in situ from their corresponding amine, hydroxylamine, and nitroxyl compounds. The oxidized cellulose is then stabilized against D.P. loss and color reversion by further treatment with an oxidant such as sodium chlorite, a chlorine dioxide / hydrogen peroxide mixture, or a peracid under acidic conditions. Alternatively it may be treated with a reducing agent such as sodium borohydride. The method results in a high percentage of carboxyl groups located at the fiber surface. The product is especially useful as a papermaking fiber where it contributes strength and has a higher attraction for cationic additives. The product is also useful as an additive to recycled fiber to increase strength. The method can be used to improve properties of either virgin or recycled fiber. It does not require high alpha-cellulose fiber but is suitable for regular market pulps.

Description

[0001] The present invention is a process for preparation of a heat and light stable fibrous carboxylated cellulose suitable for papermaking and related applications. The fibrous product of the invention is one in which fiber strength and degree of polymerization are not significantly sacrificed. The process is particularly environmentally advantageous since no chlorine or hypochlorite compounds are required.[0002] Cellulose is a carbohydrate consisting of a long chain of glucose units, all .beta.-linked through the 1'-4 positions. Native plant cellulose molecules may have upwards of 2200 anhydroglucose units. The number of units is normally referred to as degree of polymerization or simply D.P. Some loss of D.P. inevitably occurs during purification. A D.P. approaching 2000 is usually found only in purified cotton linters. Wood derived celluloses rarely exceed a D.P. of about 1700. The structure of cellulose can be represented as follows: 1[0003] Chemical derivatives of cellulose h...

Claims

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Application Information

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IPC IPC(8): C08B15/04D21C9/00D21H11/20D21H13/04
CPCC08B15/04D21C9/002D21H11/20
Inventor WEERAWARNA, S. ANANDAKOMEN, JOSEPH LINCOLNJEWELL, RICHARD A.
Owner WEYERHAEUSER CO
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