CA2063365A1 - Process for derivatizing polygalactomannans using glyoxal in the process - Google Patents
Process for derivatizing polygalactomannans using glyoxal in the processInfo
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- glyoxal
- water
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Abstract
Abstract of the Invention In an aqueous process for derivatizing polygalactomannan gums, the derivatized product prior to washing is reacted with glyoxal under acid pH conditions and, after washing, is reacted with a base. The resulting derivatized polygalactomannan gums hydrate readily under both acid and alkaline pH conditions.
Description
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DOCRET NO. P-493 Process for Derivatizing Polygalactomannans Using Glyoxal in the Process Backqround of the Invention the field of art to which this invention pertains is polygalactomannans and derivatives thereof.
Derivatives of polygalactomannans, such as the hydroxyalkyl ether, alkyl ether, carboxyalkyl ethers, aminoalkyl ether and quaternary ammonium alkyl ether derivatives, are well known compounds and various methods of preparing the derivatives have been described.
The hydroxyalkyl ethers of polygalactomannans are prepared by reacting the polygalactomannans with alkylene oxides under basic conditions. In U.S. Pat. Nos. 3,723,408 and 3,723,409, guar flour is reacted with alkylene oxides in the presence of water and sodium hydroxide. The reaction product is then neutralized with acid, washed with an alcohol-water mixture, and is then dried and ground. In U.S. Patent No. 3,483,121, the polygalactomannans and the alkylene oxides are reacted under basic conditions with small amounts of water and larger amounts of water miscible or water immiscible organic solvents.
Carboxyalkyl ethers and mixed carboxyhydroxyalkyl ethers of polygalactomannans are described in U.S. Patent Nos. 3,740,388 and 3,723,409, respectively. These derivatives are made by reacting the polygalactomannan with the derivatizing agents (halofatty acid and alkylene oxide) in a water-alcohol mixture , ~
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~ ~ , ,t followed by washing with water-alcohol mixtures.
~ ther derivatives of polygalactomannans are described in such patents as U.S. Patent No. 2,461,502 (cyanoethyl ethers), ~dS. Patent No. 4,094,795 (dialkylacrylamide ethers) and U.S.
Patent No. 3,498,912 (quaternary ammonium alkyl ethers~. In the described processes, the reactions are conducted in water-organic solvent mixtures and the reaction products are washed with solvents or water solvent mixtures.
In order to avoid the use of volatile flammable organic liquids and to eliminate the need to recover such organic liquids when the reactions are completed, commercial processes have been developed which use only water as the reaction medium. In such processes, the gum endosperm of the polygalactomannan is reacted with the derivatizing agent under alkaline catalysis using sufficient water to swell the endosperm. The resulting products are then washed to remove unreacted derivatizing agent, caustic, salt and by-products. During the washing step, care must be exercised to avoid forming gels which are extremely difficult to handle and to avoid washing away product.
The water washing problems have been minimized to a great extent by adding borax at the end of the reaction or in the wash water. Borax, under basic pH conditions, will complex with polygalactomannans to form crosslinked gels. Small amounts o~
borax in the derivati~ing reaction will complex and crosslink the surface of the swollen endosperm particles so that absorption .'-'J ~.} ~ 3 of water and solubilization of the particles is inhibited. The use of borax increases the efficiency of the process. However, the disadvantage of the process is that the resulting polygalactomannan products have a slow hydration rate under high pH conditions.
In U.S~ Patent No. 4,959,464, a process is described for derivatizing polygalactomannans gums using aluminum salts to crosslink the gum surface. Derivatized products made by this process hydrate under alkaline pH more readily than those in which borax is used. Even so, there is a need for polygalactomannan gum derivatives which hydrolyze more readily under basic conditions.
Summary of the Invention This invention is directed to a process for derivatizing polygalactomannans. In one aspect, this invention pertains to a process for derivatizing polygalactomannans under aqueous conditions. In another aspect, this invention relates to derivatives of polygalactomannans which are readily hydratable under both acidic and alkaline conditions.
By the process of this invention, derivatives of polygalactomannans are prepared by reacting the gum endosperm of the polygalactomannan with a derivatizing agent under aqueous alkaline conditions, treating the derivatized product with glyoxal at acidic pH, washing the treated produce with water, and either prior to or after centrifuging and milling the product, treating it with a base to break the glyoxal crosslinking bonds ,, . '.;
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~-q~ 3~3 and to oxidize and reduce the aldehyde groups by the Cannizzaro reaction.
DescriPtion of the Invention The proc~ss of this invention is particularly applicable to polygalactomannan gums, which gums are polysaccharides composed principally of galactose and mannose units. The polygalactomannans are usually found in the endosperm of leguminous seeds, such as guar, locust bean, honey locust, flame tree, Kentucky coffee tree, and the like. The particularly preferred polygalactomannan for use in the process of this invention is obtained from guar beans.
The basic unit of the galactomannan polymer in guar gum contains two mannose units with a glycosidic linkage and a galactose unit attached to one of the hydroxyls of the mannose unit. On average, each of the sugar units has three available hydroxyl sites, all of which can react. The extent of reaction or derivatization of the hydroxyl ~roups is referred to either as molar substitution (M.S.) which is the number of units (moles of derivatizing agent) which has reacted per sugar unit of the polygalactomannan, or degree of substitution (D.S.) which is the average number of hydroxy groups of the sugar units that has been reacted with the derivatizing agent.
The guar endosperm as used in this invention is commonly referred to as "purified splits~, or ~double purified splits"
depending upon the degree of purification. ~Purified splits" are obtained by mechanical separation of the endosperm from the hull _4_ ' ~ ;
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and germ of the guar seed in as pure and intact a form as possible with ~o other processing steps. These purified splits contain, as impurities, about 6-12 percent moisture, 2-7 percent protein and 2-7 percent acid insoluble residue. They have a particle size range of about 4 to about 20 mesh (U.S. Standard Sieve Series).
The guar particles are reacted with the various derivatizing agents under aqueous alkaline conditions. Any of the alkali metal hydroxides can be used, but the preferred one is sodium hydroxide. Water is the only reaction medium with no organic solvents being used in the process.
The derivatizing agents used in the process of this invention are the well known alkylating or etherifying agents which contain groups which can react with the hydroxyl groups of the polygalactomannans to form ether groups, such reactive groups being vicinal epoxide groups, halogen atoms, or ethylenically unsaturated groups. Examples of such agents are alkylating agents, hydroxyalkylating agents, carboxyalkylating agents, aminoalkylating agents, quaternary ammonium alkylating agents, cyanoalkylating agents, amidoalkylating agents and the like.
Alkylating agents include methyl chloride, me~hyl bromide, ethyl chloride, ethyl io~ide and isopropyl chloride. Hydroxyalkylating agents include ethylene oxide, propylene oxide-1,2, butylene oxide-1,2, hexylene oxide-1,2, ethylene chlorohydrin, propylene chlorohydrin, and epichlorohydrin. Examples of carboxyalkylating agents are chloroacetic acid, chloropropionic acid, and acrylic -, . . .
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acid. Aminoalkylating agents include aminoethyl chloride, aminopropyl bromide, N,N-dimethyl-aminopropyl chloride and the like. Quaternary ammonium alkylating agents are such agents as 2,3-epoxypropyl trimethylammonium chloride, 3-chloro-2-hydroxypropyl trimethylammonium chloride and the like.
Ethylenically unsaturated group containing agents which react through Michael addition with hydroxyl groups are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, acrylic acid, sodium acrylate and any of the polymerizable monomers which contain one ethylenically unsaturated polymerizable group.
The derivatizing reaction is conducted in a reactor capable of withstanding vacuum and moderate pressures and is equipped with means for agitating the reactants. Air is excluded from the reactor in order to prevent oxidation of the galactomannan polymer to lower molecular weight species so as to preserve the viscosity properties of the final product. The reaction is conducted under an inert gas, e.g., nitrogen, atmosphere. The polygalactomannan particles, alkali and derivatizing agent are added to the reactor with sufficient water to swell the polygalactomannan particles but not to solubilize ~hem.
Generally, the amounts of reactants, on a weight basis, used for each 100 parts of polygalactomannan gum (on a dry basis) will range from about 7.5 to about 300 parts of water (including water in the gum), about 5 to about 300 parts of derivatizing agent and ;
' -6-alkali, either in catalytic amounts, or in a slight excess over stoichiometric amounts if the derivatizing agent contains active halogen atoms or acid groups.
The derivatizing reactions are generally conducted at ambient temperatures up to about 250F for a time sufficient to complete the reaction, about 0.5 to about 24 hours. The reaction is conducted under gentle mixing or tumbling agitation so as to continually expose the surfaces of the gum particles to the derivatizing agent and to keep a uniform temperature throughout the reactor without exerting shearing forces on the particles that would grind or smear them.
The product after the derivatizing stage contains, in addition to the derivat~zed polygalactomannan, unreacted alkali, alkali salts, unreacted derivatizing agent, hydrolyzed derivatizing agent and water. The derivatized polygalactomannan is contacted with water to extract~and wash out the undesirable by-products. The washing stage is conducted by well known processes such as slurry and decantation, counter current washing, and centrifuging. During the washing stage, the polygalactomannan particles absorb water and if the washing is not properly controlled, the particles will become jelly like and will actually dissolve in the water. In order to be handleable : and processable, the water content of the particles, as measured ~fter centrifugation, should not exceed about 80 weight percent.
If the polygalactomannan derivatives are treated with a small amount of borax before or during the washing step, the surface of :`
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.: , the polygalactomannan is crosslinked, thereby decreasinq the ability of the particle to absorb more water and also helping to retain the integrity of the particle. As described in U.S.
Patent No. 3,808,19~, when borax and polygalactomannan particles are added to water, the borax retards the development of stickiness on the particles' surfaces ~y forming a thin film of crosslinked polymer on the surface. Although the use of borax is helpful in the processing of polygalactomannan derivatives, its presence in the polymer results in slow hydration rate of the derivatives at alkaline p~.
A similar process is described in U.S. Patent No. 4,959,464 wherein aluminum salts are used in place of borax to crosslink the surface of the polygalactomannan. Although the hydration rate of the products under alkaline pH is much improved over that of the borax treated products, the hydration rate is still too slow for some processes.
According to the process of this invention, glyoxal is mixed with the products and by-products of the derivatizing stage before the washing step. The pH is then adjusted to the acid side, whereby the glyoxal crosslinks the surface of the polygalactomannan particles, thereby inhibiting the absorption of water into the particles and reducing the stickiness of the surface of particles in a manner similar to borax and aluminum salts. The derivatized polygalactomannans are then washed with water to remove by-products and are centrifuged to remove the :
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9 ~ ~ ~ J .` 1 excess water leaving particles having a moisture content (post-centrifuge moisture) of about 60 to about 80 weight percent. The particles are then flash ground, i.e., ground to reduce particle size and at the same time moisture is evaporated under heat. Flash grinding can be conducted in a hammer ~ill through which heated air is passed. In the flash grinding operation, the particle size is reduced to about 100 to about 200 mesh (US Standard Sieve) and the moisture content is reduced to about 10 percent by weight.
The resulting polygalactomannan derivative dried powder, which is partially crosslinked with glyoxal and hydrates slowly, is then treated with a base to break the glyoxal crosslinking bonds and to convert the aldehyde groups to alcohol and acid groups (Cannizzaro reaction).
Sufficient base is added to raise the pH of the derivatized polygalactomannan to at least 10 and preferably to about 10.5 to about 11.5. The base can be added to the powder as an aqueous solution which is thoroughly mixed with the powder. However in order to obtain uniform mixing and a uniform product, the base is preferably mixed with a lower alcohol and this mixture is added to the powder. The alcohol is then removed from the powder by air drying or with the application of heat up to about 40C.
In an alternate and preferred process, the base is added to the derivatized polygalactomannan after the centrifuging step but prior to the milling step.
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The amount of glyoxal used in the process of this invention is about 0.2 to about 2 weight percent based on the weight of polygalactomannan originally present. The glyoxal crosslin~ing reaction is conducted under acidic pH conditions, generally at a pH of about 1 to about 6.5. The acid used for acidification can be any of the well known mineral or water soluble organic acids.
Preferably the acid is acetic acid.
Any of the well known water soluble bases can be used to raise the pH to 10 or higher. Such bases include alkali metal hydroxides, amines, and ammonia. The preferred bases are sodium and potassium hydroxide and the lower alkyl tertiary amines, i.e., tertiary amines which contain 3 to about 9 carbon atoms in their alkyl groups. ~he most preferred base is sodium hydroxide which is usually adde~ as an aqueous solution, about 15 to about 50 percent sodium hydroxide in water.
In using the bases, they are preferably added mixed with a lower alcohol, i.e., methanol, ethanol or isopropanol, preferably methanol, wherein the amount of alcohol used is at least about 25 percent of the weight of the dried powder. Theoretically, there is no upper limit to the amount of alcohol that can be used.
However, for reasons of economy and practicality, the upper limit is tha~ amount which is equal in weight to the weisht of the powder.
When the base reacting step is conducted on the post centrifuge gel before drying, the base can be added as an aqueous solution wherein the amount of water is about equal to the total water and alcohol used in the powder process.
The derivatized polygalactomannans obtained by the process of this invention hydrate rapidly under both acidic and basic conditions and find utility in many processes wherein low hydration rate has been a problem.
The following examples describe the invention in more detail. Paxts and percentages are by weight unless otherwise designated.
ExamPle 1 To a suitable reactor are added 1750 parts of water and 162 parts of 50 percent aqueous sodium hydroxide. Agitation is begun and the temperature is raised to 155F. Double purified guar splits, 2000 parts, are added, the reactor is sealed, is purged with nitrogen and is evacuated three times. Propylene oxide, 460 parts, is added while controlling the pressure rise to about 10 psig. After about 30 minutes, the pressure drops to 0 indicating complete reaction of the propylene oxide. The temperature is lowered to 80F, followed by the addition of 13 parts by volume of 40 percent aqueous glyoxal solution and 180 parts by volume of glacial acetic acid. The mixture is agitated for 20 minutes.
Thirty minutes after the glyoxal addition, the product is washed 3 times with water, followed by decanting the water after each washing step. The product is then centrifuged and the moisture content is determined to be 74.0 percent. The product , '~ ' ' ~; ' ' -:
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is then milled and dried to a moisture content of about 10 percent.
Twenty parts of the hydroxypropyl guar product is thoroughly mixed with 0.2 part of triethylamine and 10 parts by volume of methanol. The mixture is heated in an oven at 100-110F to dry the product.
The pH of a 1 percent aqueous solution of the dried product is 7.5. (Ex lA).
Another 20 part portion of the hydroxypropyl guar product is treated with 2.0 parts of triethylamine and 10 parts by volume of methanol. ~fter heating in an oven at 100-110F, the dried product as a 1 percent aqueous solution has a p~ of 10.0 ~Ex lB).
A one percent aqueous solution of the hydroxypropyl guar product with no base treatment has a pH of 5.5. (Ex lC).
Each of the above products is added to water containing 2 percent potassium chloride and buffered to a pH of 8.0 with monosodium dihydrogen phosphate and sodium hydroxide. Each product is added at a concentration of 1.92 grams in 400 mls of aqueous solution. The rate of hydration is determined by measuring the viscosity, expressed in centipose, with a Fann 35A
Viscometer. The pH of each solution is measured after 10 minutes hydration. The hydration rates, initial pH and 10 minute pH are shown in Table 1.
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Ex. pH Minutes pH Minutes 2 3 4 5 10 30 _60 lA 8.0 104 131 147 154 161 7.99 162 163 lB 8.0 124 140 14~ 152 158 8.09 159 160 lC 8.0 80 116 136 146 156 7.93 158 157 Using the same procedure described in Example 1, carboxymethyl-hydroxypropyl guar is prepared by reacting the following components:
100 parts o double purified guar splits, 15.74 parts of sodium monochloroacetate, 16.4 parts of 50 percent aqueous sodium hydroxide, 23.0 parts of propylene oxide.
When the reaction is completed, the reaction mass is cooled to 100F and 3.5 parts of glyoxal (40 percent in water) and 10 parts of glacial acetic acid are added. The reaction mass is mixed for 30 minutes. The mass is then washed twice with 60-70F
water for 3 minutes and is then centrifuged. The post centrifuge moisture content is measured as 73-75.8 percent. The gel i5 not sticky and is easily ground and dried to a powder. The inherent pH, the pH of a 1 percent aquec>us solution, is 6.5.
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Twenty parts of the carboxymethyl hydroxypropyl guar powder is mixed with 20 parts by volume of methanol and 0.2 part of 50 percent aqueous caustic. After thorough mixing, the methanol is removed by heating in an oven at 100~110F.
The caustic treatment is repeated as described above except the amount of aqueous caustic used is increased to 0.3, 0.45, 0.6 and 0.75 part. The caustic treated products are identified in Table 2.
Each of the caustic treated products is added to water containing 2 percent potassium chloride buffered to a pH of 8 with monosodium dihydrogen phosphate and sodium hydroxide. Each product is added at a concentration of 1.92 grams in 400 mls of aqueous solution. The hydration rate is determined by measuring the viscosity, expressed in centipose, with a Fann 35A
Viscometer. The pH of each solution is measured after 10 minutes hydration.
Measurements of hydration rate are also made with solutions buffered at pH 7.0 and at 5Ø
The hydration rate, initial buffered pH, and pH after 10 minutes hydration are shown in Table 3.
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Example Added Caustic ~ 50 % aqueous ) 2B 0.2 2E 0.6 . , ~ , . , ~, .. .. . .
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Example pH Minutes pH Minutes _ 2 3 5 10 30 60 2A 8.018 45 110135 8.01 140 140 2B 8.031 66 109133 8.07 138 140 2D 8.083 90 103115 8.08 127 130 2E 8.0110115 122126 8.10 130 132 2F 8.0120125 129131 8.10 132 133 2A 7.0 6 7 8 32 7.08 130 131 2B 7.0 6 9 11 53 7.11 130 133 2C 7.0 7 9 12 44 7.13 130 135 2D 7.053 59 73 93 7.06 llS 120 2E 7.092 97 104116 7.07 128 130 2F 7.0118121 123128 7.05 130 130 2D 5.031 34 37 45 5.3 70 90 2E S .082 85 90 90 5.4 104 115 2F 5.0112114 117120 5.5 120 122 , .
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~ 13 ~ ~ i ' The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
DOCRET NO. P-493 Process for Derivatizing Polygalactomannans Using Glyoxal in the Process Backqround of the Invention the field of art to which this invention pertains is polygalactomannans and derivatives thereof.
Derivatives of polygalactomannans, such as the hydroxyalkyl ether, alkyl ether, carboxyalkyl ethers, aminoalkyl ether and quaternary ammonium alkyl ether derivatives, are well known compounds and various methods of preparing the derivatives have been described.
The hydroxyalkyl ethers of polygalactomannans are prepared by reacting the polygalactomannans with alkylene oxides under basic conditions. In U.S. Pat. Nos. 3,723,408 and 3,723,409, guar flour is reacted with alkylene oxides in the presence of water and sodium hydroxide. The reaction product is then neutralized with acid, washed with an alcohol-water mixture, and is then dried and ground. In U.S. Patent No. 3,483,121, the polygalactomannans and the alkylene oxides are reacted under basic conditions with small amounts of water and larger amounts of water miscible or water immiscible organic solvents.
Carboxyalkyl ethers and mixed carboxyhydroxyalkyl ethers of polygalactomannans are described in U.S. Patent Nos. 3,740,388 and 3,723,409, respectively. These derivatives are made by reacting the polygalactomannan with the derivatizing agents (halofatty acid and alkylene oxide) in a water-alcohol mixture , ~
.:, ., , :: - :
, .::. i ., .
~ ~ , ,t followed by washing with water-alcohol mixtures.
~ ther derivatives of polygalactomannans are described in such patents as U.S. Patent No. 2,461,502 (cyanoethyl ethers), ~dS. Patent No. 4,094,795 (dialkylacrylamide ethers) and U.S.
Patent No. 3,498,912 (quaternary ammonium alkyl ethers~. In the described processes, the reactions are conducted in water-organic solvent mixtures and the reaction products are washed with solvents or water solvent mixtures.
In order to avoid the use of volatile flammable organic liquids and to eliminate the need to recover such organic liquids when the reactions are completed, commercial processes have been developed which use only water as the reaction medium. In such processes, the gum endosperm of the polygalactomannan is reacted with the derivatizing agent under alkaline catalysis using sufficient water to swell the endosperm. The resulting products are then washed to remove unreacted derivatizing agent, caustic, salt and by-products. During the washing step, care must be exercised to avoid forming gels which are extremely difficult to handle and to avoid washing away product.
The water washing problems have been minimized to a great extent by adding borax at the end of the reaction or in the wash water. Borax, under basic pH conditions, will complex with polygalactomannans to form crosslinked gels. Small amounts o~
borax in the derivati~ing reaction will complex and crosslink the surface of the swollen endosperm particles so that absorption .'-'J ~.} ~ 3 of water and solubilization of the particles is inhibited. The use of borax increases the efficiency of the process. However, the disadvantage of the process is that the resulting polygalactomannan products have a slow hydration rate under high pH conditions.
In U.S~ Patent No. 4,959,464, a process is described for derivatizing polygalactomannans gums using aluminum salts to crosslink the gum surface. Derivatized products made by this process hydrate under alkaline pH more readily than those in which borax is used. Even so, there is a need for polygalactomannan gum derivatives which hydrolyze more readily under basic conditions.
Summary of the Invention This invention is directed to a process for derivatizing polygalactomannans. In one aspect, this invention pertains to a process for derivatizing polygalactomannans under aqueous conditions. In another aspect, this invention relates to derivatives of polygalactomannans which are readily hydratable under both acidic and alkaline conditions.
By the process of this invention, derivatives of polygalactomannans are prepared by reacting the gum endosperm of the polygalactomannan with a derivatizing agent under aqueous alkaline conditions, treating the derivatized product with glyoxal at acidic pH, washing the treated produce with water, and either prior to or after centrifuging and milling the product, treating it with a base to break the glyoxal crosslinking bonds ,, . '.;
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~-q~ 3~3 and to oxidize and reduce the aldehyde groups by the Cannizzaro reaction.
DescriPtion of the Invention The proc~ss of this invention is particularly applicable to polygalactomannan gums, which gums are polysaccharides composed principally of galactose and mannose units. The polygalactomannans are usually found in the endosperm of leguminous seeds, such as guar, locust bean, honey locust, flame tree, Kentucky coffee tree, and the like. The particularly preferred polygalactomannan for use in the process of this invention is obtained from guar beans.
The basic unit of the galactomannan polymer in guar gum contains two mannose units with a glycosidic linkage and a galactose unit attached to one of the hydroxyls of the mannose unit. On average, each of the sugar units has three available hydroxyl sites, all of which can react. The extent of reaction or derivatization of the hydroxyl ~roups is referred to either as molar substitution (M.S.) which is the number of units (moles of derivatizing agent) which has reacted per sugar unit of the polygalactomannan, or degree of substitution (D.S.) which is the average number of hydroxy groups of the sugar units that has been reacted with the derivatizing agent.
The guar endosperm as used in this invention is commonly referred to as "purified splits~, or ~double purified splits"
depending upon the degree of purification. ~Purified splits" are obtained by mechanical separation of the endosperm from the hull _4_ ' ~ ;
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and germ of the guar seed in as pure and intact a form as possible with ~o other processing steps. These purified splits contain, as impurities, about 6-12 percent moisture, 2-7 percent protein and 2-7 percent acid insoluble residue. They have a particle size range of about 4 to about 20 mesh (U.S. Standard Sieve Series).
The guar particles are reacted with the various derivatizing agents under aqueous alkaline conditions. Any of the alkali metal hydroxides can be used, but the preferred one is sodium hydroxide. Water is the only reaction medium with no organic solvents being used in the process.
The derivatizing agents used in the process of this invention are the well known alkylating or etherifying agents which contain groups which can react with the hydroxyl groups of the polygalactomannans to form ether groups, such reactive groups being vicinal epoxide groups, halogen atoms, or ethylenically unsaturated groups. Examples of such agents are alkylating agents, hydroxyalkylating agents, carboxyalkylating agents, aminoalkylating agents, quaternary ammonium alkylating agents, cyanoalkylating agents, amidoalkylating agents and the like.
Alkylating agents include methyl chloride, me~hyl bromide, ethyl chloride, ethyl io~ide and isopropyl chloride. Hydroxyalkylating agents include ethylene oxide, propylene oxide-1,2, butylene oxide-1,2, hexylene oxide-1,2, ethylene chlorohydrin, propylene chlorohydrin, and epichlorohydrin. Examples of carboxyalkylating agents are chloroacetic acid, chloropropionic acid, and acrylic -, . . .
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acid. Aminoalkylating agents include aminoethyl chloride, aminopropyl bromide, N,N-dimethyl-aminopropyl chloride and the like. Quaternary ammonium alkylating agents are such agents as 2,3-epoxypropyl trimethylammonium chloride, 3-chloro-2-hydroxypropyl trimethylammonium chloride and the like.
Ethylenically unsaturated group containing agents which react through Michael addition with hydroxyl groups are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, acrylic acid, sodium acrylate and any of the polymerizable monomers which contain one ethylenically unsaturated polymerizable group.
The derivatizing reaction is conducted in a reactor capable of withstanding vacuum and moderate pressures and is equipped with means for agitating the reactants. Air is excluded from the reactor in order to prevent oxidation of the galactomannan polymer to lower molecular weight species so as to preserve the viscosity properties of the final product. The reaction is conducted under an inert gas, e.g., nitrogen, atmosphere. The polygalactomannan particles, alkali and derivatizing agent are added to the reactor with sufficient water to swell the polygalactomannan particles but not to solubilize ~hem.
Generally, the amounts of reactants, on a weight basis, used for each 100 parts of polygalactomannan gum (on a dry basis) will range from about 7.5 to about 300 parts of water (including water in the gum), about 5 to about 300 parts of derivatizing agent and ;
' -6-alkali, either in catalytic amounts, or in a slight excess over stoichiometric amounts if the derivatizing agent contains active halogen atoms or acid groups.
The derivatizing reactions are generally conducted at ambient temperatures up to about 250F for a time sufficient to complete the reaction, about 0.5 to about 24 hours. The reaction is conducted under gentle mixing or tumbling agitation so as to continually expose the surfaces of the gum particles to the derivatizing agent and to keep a uniform temperature throughout the reactor without exerting shearing forces on the particles that would grind or smear them.
The product after the derivatizing stage contains, in addition to the derivat~zed polygalactomannan, unreacted alkali, alkali salts, unreacted derivatizing agent, hydrolyzed derivatizing agent and water. The derivatized polygalactomannan is contacted with water to extract~and wash out the undesirable by-products. The washing stage is conducted by well known processes such as slurry and decantation, counter current washing, and centrifuging. During the washing stage, the polygalactomannan particles absorb water and if the washing is not properly controlled, the particles will become jelly like and will actually dissolve in the water. In order to be handleable : and processable, the water content of the particles, as measured ~fter centrifugation, should not exceed about 80 weight percent.
If the polygalactomannan derivatives are treated with a small amount of borax before or during the washing step, the surface of :`
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.: , the polygalactomannan is crosslinked, thereby decreasinq the ability of the particle to absorb more water and also helping to retain the integrity of the particle. As described in U.S.
Patent No. 3,808,19~, when borax and polygalactomannan particles are added to water, the borax retards the development of stickiness on the particles' surfaces ~y forming a thin film of crosslinked polymer on the surface. Although the use of borax is helpful in the processing of polygalactomannan derivatives, its presence in the polymer results in slow hydration rate of the derivatives at alkaline p~.
A similar process is described in U.S. Patent No. 4,959,464 wherein aluminum salts are used in place of borax to crosslink the surface of the polygalactomannan. Although the hydration rate of the products under alkaline pH is much improved over that of the borax treated products, the hydration rate is still too slow for some processes.
According to the process of this invention, glyoxal is mixed with the products and by-products of the derivatizing stage before the washing step. The pH is then adjusted to the acid side, whereby the glyoxal crosslinks the surface of the polygalactomannan particles, thereby inhibiting the absorption of water into the particles and reducing the stickiness of the surface of particles in a manner similar to borax and aluminum salts. The derivatized polygalactomannans are then washed with water to remove by-products and are centrifuged to remove the :
,~ .
9 ~ ~ ~ J .` 1 excess water leaving particles having a moisture content (post-centrifuge moisture) of about 60 to about 80 weight percent. The particles are then flash ground, i.e., ground to reduce particle size and at the same time moisture is evaporated under heat. Flash grinding can be conducted in a hammer ~ill through which heated air is passed. In the flash grinding operation, the particle size is reduced to about 100 to about 200 mesh (US Standard Sieve) and the moisture content is reduced to about 10 percent by weight.
The resulting polygalactomannan derivative dried powder, which is partially crosslinked with glyoxal and hydrates slowly, is then treated with a base to break the glyoxal crosslinking bonds and to convert the aldehyde groups to alcohol and acid groups (Cannizzaro reaction).
Sufficient base is added to raise the pH of the derivatized polygalactomannan to at least 10 and preferably to about 10.5 to about 11.5. The base can be added to the powder as an aqueous solution which is thoroughly mixed with the powder. However in order to obtain uniform mixing and a uniform product, the base is preferably mixed with a lower alcohol and this mixture is added to the powder. The alcohol is then removed from the powder by air drying or with the application of heat up to about 40C.
In an alternate and preferred process, the base is added to the derivatized polygalactomannan after the centrifuging step but prior to the milling step.
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The amount of glyoxal used in the process of this invention is about 0.2 to about 2 weight percent based on the weight of polygalactomannan originally present. The glyoxal crosslin~ing reaction is conducted under acidic pH conditions, generally at a pH of about 1 to about 6.5. The acid used for acidification can be any of the well known mineral or water soluble organic acids.
Preferably the acid is acetic acid.
Any of the well known water soluble bases can be used to raise the pH to 10 or higher. Such bases include alkali metal hydroxides, amines, and ammonia. The preferred bases are sodium and potassium hydroxide and the lower alkyl tertiary amines, i.e., tertiary amines which contain 3 to about 9 carbon atoms in their alkyl groups. ~he most preferred base is sodium hydroxide which is usually adde~ as an aqueous solution, about 15 to about 50 percent sodium hydroxide in water.
In using the bases, they are preferably added mixed with a lower alcohol, i.e., methanol, ethanol or isopropanol, preferably methanol, wherein the amount of alcohol used is at least about 25 percent of the weight of the dried powder. Theoretically, there is no upper limit to the amount of alcohol that can be used.
However, for reasons of economy and practicality, the upper limit is tha~ amount which is equal in weight to the weisht of the powder.
When the base reacting step is conducted on the post centrifuge gel before drying, the base can be added as an aqueous solution wherein the amount of water is about equal to the total water and alcohol used in the powder process.
The derivatized polygalactomannans obtained by the process of this invention hydrate rapidly under both acidic and basic conditions and find utility in many processes wherein low hydration rate has been a problem.
The following examples describe the invention in more detail. Paxts and percentages are by weight unless otherwise designated.
ExamPle 1 To a suitable reactor are added 1750 parts of water and 162 parts of 50 percent aqueous sodium hydroxide. Agitation is begun and the temperature is raised to 155F. Double purified guar splits, 2000 parts, are added, the reactor is sealed, is purged with nitrogen and is evacuated three times. Propylene oxide, 460 parts, is added while controlling the pressure rise to about 10 psig. After about 30 minutes, the pressure drops to 0 indicating complete reaction of the propylene oxide. The temperature is lowered to 80F, followed by the addition of 13 parts by volume of 40 percent aqueous glyoxal solution and 180 parts by volume of glacial acetic acid. The mixture is agitated for 20 minutes.
Thirty minutes after the glyoxal addition, the product is washed 3 times with water, followed by decanting the water after each washing step. The product is then centrifuged and the moisture content is determined to be 74.0 percent. The product , '~ ' ' ~; ' ' -:
.: : . . .
~ ,~
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is then milled and dried to a moisture content of about 10 percent.
Twenty parts of the hydroxypropyl guar product is thoroughly mixed with 0.2 part of triethylamine and 10 parts by volume of methanol. The mixture is heated in an oven at 100-110F to dry the product.
The pH of a 1 percent aqueous solution of the dried product is 7.5. (Ex lA).
Another 20 part portion of the hydroxypropyl guar product is treated with 2.0 parts of triethylamine and 10 parts by volume of methanol. ~fter heating in an oven at 100-110F, the dried product as a 1 percent aqueous solution has a p~ of 10.0 ~Ex lB).
A one percent aqueous solution of the hydroxypropyl guar product with no base treatment has a pH of 5.5. (Ex lC).
Each of the above products is added to water containing 2 percent potassium chloride and buffered to a pH of 8.0 with monosodium dihydrogen phosphate and sodium hydroxide. Each product is added at a concentration of 1.92 grams in 400 mls of aqueous solution. The rate of hydration is determined by measuring the viscosity, expressed in centipose, with a Fann 35A
Viscometer. The pH of each solution is measured after 10 minutes hydration. The hydration rates, initial pH and 10 minute pH are shown in Table 1.
. ~,. . .
,.................................................. :
., ~, ' ~
f ~ r C~ ~ i TABLE
Ex. pH Minutes pH Minutes 2 3 4 5 10 30 _60 lA 8.0 104 131 147 154 161 7.99 162 163 lB 8.0 124 140 14~ 152 158 8.09 159 160 lC 8.0 80 116 136 146 156 7.93 158 157 Using the same procedure described in Example 1, carboxymethyl-hydroxypropyl guar is prepared by reacting the following components:
100 parts o double purified guar splits, 15.74 parts of sodium monochloroacetate, 16.4 parts of 50 percent aqueous sodium hydroxide, 23.0 parts of propylene oxide.
When the reaction is completed, the reaction mass is cooled to 100F and 3.5 parts of glyoxal (40 percent in water) and 10 parts of glacial acetic acid are added. The reaction mass is mixed for 30 minutes. The mass is then washed twice with 60-70F
water for 3 minutes and is then centrifuged. The post centrifuge moisture content is measured as 73-75.8 percent. The gel i5 not sticky and is easily ground and dried to a powder. The inherent pH, the pH of a 1 percent aquec>us solution, is 6.5.
.
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Twenty parts of the carboxymethyl hydroxypropyl guar powder is mixed with 20 parts by volume of methanol and 0.2 part of 50 percent aqueous caustic. After thorough mixing, the methanol is removed by heating in an oven at 100~110F.
The caustic treatment is repeated as described above except the amount of aqueous caustic used is increased to 0.3, 0.45, 0.6 and 0.75 part. The caustic treated products are identified in Table 2.
Each of the caustic treated products is added to water containing 2 percent potassium chloride buffered to a pH of 8 with monosodium dihydrogen phosphate and sodium hydroxide. Each product is added at a concentration of 1.92 grams in 400 mls of aqueous solution. The hydration rate is determined by measuring the viscosity, expressed in centipose, with a Fann 35A
Viscometer. The pH of each solution is measured after 10 minutes hydration.
Measurements of hydration rate are also made with solutions buffered at pH 7.0 and at 5Ø
The hydration rate, initial buffered pH, and pH after 10 minutes hydration are shown in Table 3.
\j 3 ~~ $ ~ ~ J
Example Added Caustic ~ 50 % aqueous ) 2B 0.2 2E 0.6 . , ~ , . , ~, .. .. . .
. ~ .- , . ... .
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, ; . ~ :~ '` ~
~,J ~ 1 7 ,, ~
Example pH Minutes pH Minutes _ 2 3 5 10 30 60 2A 8.018 45 110135 8.01 140 140 2B 8.031 66 109133 8.07 138 140 2D 8.083 90 103115 8.08 127 130 2E 8.0110115 122126 8.10 130 132 2F 8.0120125 129131 8.10 132 133 2A 7.0 6 7 8 32 7.08 130 131 2B 7.0 6 9 11 53 7.11 130 133 2C 7.0 7 9 12 44 7.13 130 135 2D 7.053 59 73 93 7.06 llS 120 2E 7.092 97 104116 7.07 128 130 2F 7.0118121 123128 7.05 130 130 2D 5.031 34 37 45 5.3 70 90 2E S .082 85 90 90 5.4 104 115 2F 5.0112114 117120 5.5 120 122 , .
.:
~ 13 ~ ~ i ' The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.
Claims (12)
1. In a process for preparing derivatives of a polygalactomannan gum which comprises reacting the gum with a derivatizing agent in aqueous medium followed by the steps of washing with water, milling and drying, the improvement which comprises reacting the gum after the derivatizing reaction and prior to the washing step with glyoxal at an acidic pH whereby the surface of the gum particles is crosslinked thereby inhibiting absorption of the wash water into the gum particles and after the washing step treating the derivatized guar with base to break the glyoxal crosslinks.
2. The process of Claim 1 wherein the polygalactomannan gum is guar gum.
3. The process of Claim 2 wherein the guar gum is in the form of splits.
4. The process of Claim 1 wherein the glyoxal is reacted in the amount of about 0.2 to about 2 weight percent based on the weight of polygalactomannan gum prior to derivatizing.
5. The process of Claim 1 wherein the glyoxal is reacted at a pH of about 1 to about 6.5.
6. The process of Claim l wherein the base is sodium hydroxide.
7. The process of Claim 1 wherein sufficient base is added to raise the pH to at least 10.
8. The process of Claim 7 wherein the pH is raised to about 10.5 to about 11.5.
9. The process of Claim 1 wherein the derivatizing agent is an etherifying agent.
10. The process of Claim 9 wherein the derivatizing agent contains a vicinal epoxide group, a halogen atom, or an ethylenically unsaturated group.
11. The process of Claim 10 wherein the derivatizing agent is propylene oxide.
12. The process of Claim 10 wherein the derivatizing agent is chloroacetic acid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US78317491A | 1991-10-28 | 1991-10-28 | |
| US783,174 | 1997-01-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2063365C CA2063365C (en) | 1993-04-29 |
| CA2063365A1 true CA2063365A1 (en) | 1993-04-29 |
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ID=25128410
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2063365 Granted CA2063365A1 (en) | 1991-10-28 | 1992-03-18 | Process for derivatizing polygalactomannans using glyoxal in the process |
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| Country | Link |
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| CA (1) | CA2063365A1 (en) |
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| WO2003078473A1 (en) * | 2002-03-18 | 2003-09-25 | Lamberti Spa | Building additives based on purified hydroxyalkyl guar |
| WO2008057425A1 (en) * | 2006-11-03 | 2008-05-15 | Hercules Incorporated | Dispersible glyoxal treated cationi c polygalactomannan polymers |
| WO2008058768A1 (en) * | 2006-11-17 | 2008-05-22 | Lamberti Spa | Procedure for the preparation of glyoxalated cationic guar |
| EP2343322A1 (en) | 2010-01-07 | 2011-07-13 | Lamberti SPA | Glyoxal free purified cationic polygalactomannan |
| WO2012136747A1 (en) | 2011-04-07 | 2012-10-11 | Lamberti Spa | Method of treating subterranean formations |
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| CN108752493A (en) * | 2018-05-24 | 2018-11-06 | 重庆美杉蓝科技发展有限公司 | A kind of cation guar gum production technology |
| CN114213554A (en) * | 2021-12-31 | 2022-03-22 | 昆山京昆油田化学科技有限公司 | Purification method of cationic guar gum |
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1992
- 1992-03-18 CA CA 2063365 patent/CA2063365A1/en active Granted
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| JP2015232011A (en) * | 2006-11-03 | 2015-12-24 | ハーキュリーズ・インコーポレーテッドＨｅｒｃｕｌｅｓ Ｉｎｃｏｒｐｏｒａｔｅｄ | Dispersible cationic polygalactomannan polymer treated with glyoxal |
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| JP2010509218A (en) * | 2006-11-03 | 2010-03-25 | ハーキュリーズ・インコーポレーテッド | Dispersible cationic polygalactomannan polymer treated with glyoxal |
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| WO2008057425A1 (en) * | 2006-11-03 | 2008-05-15 | Hercules Incorporated | Dispersible glyoxal treated cationi c polygalactomannan polymers |
| KR101464390B1 (en) * | 2006-11-03 | 2014-11-21 | 허큘레스 인코포레이티드 | Dispersible glyoxal treated cationic polygalactomannan polymers |
| JP2010510335A (en) * | 2006-11-17 | 2010-04-02 | ランベルティ ソシエタ ペル アチオニ | Procedure for the preparation of glyoxalated cationic guar |
| US20100004197A1 (en) * | 2006-11-17 | 2010-01-07 | Lamberti Spa | Procedure for the preparation of glyoxalated cationic guar |
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| WO2008058768A1 (en) * | 2006-11-17 | 2008-05-22 | Lamberti Spa | Procedure for the preparation of glyoxalated cationic guar |
| US8785622B2 (en) | 2008-01-31 | 2014-07-22 | Rhodia Operations | Crosslinked polysaccharides and methods of production thereof |
| US8580952B2 (en) | 2010-01-07 | 2013-11-12 | Lamberti Spa | Glyoxal free purified cationic polygalactomannan |
| EP2343322A1 (en) | 2010-01-07 | 2011-07-13 | Lamberti SPA | Glyoxal free purified cationic polygalactomannan |
| WO2012136747A1 (en) | 2011-04-07 | 2012-10-11 | Lamberti Spa | Method of treating subterranean formations |
| CN108752493A (en) * | 2018-05-24 | 2018-11-06 | 重庆美杉蓝科技发展有限公司 | A kind of cation guar gum production technology |
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