CA2023324A1 - Process for preparing hydrophobically modified guar ethers - Google Patents

Abstract

Abstract of Disclosure Hydrophilic-hydrophobic derivatives of guar are made by a two step reaction wherein in the first step, hydrophilic reagents are reacted with guar splits under aqueous alkaline conditions, and without isolating the product, hydrophobic reagents dissolved in an organic solvent are reacted with the guar still in particulate form.

Description

A ~ ~ ~ ~ Express Mail Certificate No.:
U ~ B10080433 DOC~ET NO.: P~523 Process for Preparing Hydrophobically Modified Guar Ethers Cross Reference This application is related to U.S. Patent No. 4,870,167, which issued September 26, 1989.
Back~round of Invention The field of art to which this invention is directed is polysaccharide derivatives.
Polygalactomannans and the~r derivatives are well known compositions which have many uses as thickening agents in aqueous systems.
Guar gum is a polygalactomannan which essentially is a straight chain mannose with single membered galactose branches.
The rat o of galactose to mannose in the guar polymer is 1:2.
A~kyl ethers of guar gum have been made by reacting guar spl-;s with an alk ha ide or an aik~ylene oxide. Guar gu~
~apl-ts a~Q obta ned af~er the removai of the hulk and t;e gums from guar seeds. Generally, the guar gum splits are mixed with suf'icient water and aiXal to swel' the splits but insuf_:ic:ent to form a gel. The alkyl haiide or the alkylene oxide is then added and the reaction is conducted under agitation, usua;l~ in an apparatus, sucn as a ribbon blende_. When the reaction `~
complete, the guar reaction product, still in particulate for~ is washed to remove excess alkal-, salt or other by-products. The guar gum derivative i3 then dried and flaked or powdered.

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aydrophobically modified non-ionic guar gum is disclosed in our patent, U.S. 4,870,167. The process as described in the patent involves reacting a hydrophilic guar derivat ve, e.g., hydroxypropyl guar, with a long chain hydrocarbon epoxide or halide using an organic l-quid in the process.
Hydrophobically modified guar gum is disclosed in European Patent Application No. 323,627.
Hydrophobically modified non-ionic cellulose ethers are described in U.S. Patent No. 4,228,277.
Summarv of Invention This invention is directed to a process for preparing guar gum hav ng both h~drophilic and hydrophobic substituents. In particular, this invention pertains to a process for manufactur-ng hy~rophilica'ly-hydrophobically modified gua- gu~
directly from guar bean splits.
By the process of this invention, guar gum derivatives a-e made hav~ng both hydrophilic ether substituents and hydrophobi-ether subst tuents wherein the hydrophilic ether substituent ;s selecteZ from the group consisting of RC ~nd HOR10, wherein ~ s an alkyl groLp containing one to four car~on atoms, wAerein R ~s an alkylene group containin~ two to four carbon atoms and wherein the OH grou~ ~s on the carbon atom beta to the et~er group, wherein the hydrophobic ether substituent is selected from the group consisting or R20, HoR30, and OH

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: ~ :.,: '' ' : , ., - '` ., wherein R2 is an alkyl group containing about 8 to about 28 carbon atoms, wherein R3 is an alkylene group containing about 8 to about 28 carbon atoms having the OH group on the carbon atom beta to the ether group, and wherein R is an alkyl group conta~ning about 5 to about 25 carbon atoms.
By process of this invention, guar bean splits are reacted first with an alkyl halide, RX, or a 1,2-alkylene oxide, represented herein as Rl=O, wherein R and R1 are the same as described hereinabove, to form the hydrophilic substituents under aqueous alkaline conditions us ng sufficient water to swell the guar bean splits but not to dissolve them. Without removing water or by-products, the hydrophically substituted guar splits are then reactec. with a long chain alkyl halide, R2X, a long chain, 1,2-epox_de, R3=C, or a long cha-,n glycidyl ether, R OC~2 CH-CH2, wherein R , R and C
R4 are the sa~e as described hereinbefore to form the hydrophob__ substituent, wherein the long chain ha' de, epoxide or gl~c d~l e'ner ls addea as a solution in an organic solvent whic~ s cayabie of swe'lina .he hydroohica'l~ subst tuted guar but nct dissoiving it. Suff;cient hydrophilic derivatizing agent is used to ob~a n a M.S. of abollt 0.2 to about 2. Sufficient hydrophob~c derivatizing agent is present to obtain a M.S. of about 0.001 to about 0.2. When the derivatiz ng reaction is complete, the guar product is washed with water to remove by-products and unreacted .,, ,, , ''' reagents and is dried to a moisture content below about 10 percent by weight.
Description of Invention The guar used in the process of this invention is in the form of "splits. n Since the guar bean or seed is dicotyledenous, two endosperm halves are obtained from each seed. These endosperm ha'ves surround the embryo, and they in turn are surrounded by a hull. The endosperm halves are separated from the hull and embryo by taking advantagè of the difference in hardness of the various seed components. Multistage grinding and sifting operations are combined with other physical treatments to crack the seeds and separate the parts. The separated endosperm halves are referred to in the trade as "spllts~.
~ he hydrophil1c de~ivatizing agent used in this invention ls an alkyl halide or alkylene oxide wherein the alkyl grous contalns 1 lo 4 carbon atoms and the alkylene group contains 2 tc 4 ca-bon atoma. Examples of such der vatizing agent~ are methyl ch!or'de, ethyl bromide, methyl iodide, ethylene ox_de, 1,2-?ropy'ene oxide, ;,2-butylene oxide, and 2,3-butvlene cx-'de, or mix~ures ~hereof, The hydrophobic derivatizing aqent used in this invention ~s a long aliphatic cha'n epoxy compound which contains from abcut c to about 2~ carbon atoms or an alkyl halide havin~ about 8 to about 28 carbon atoms in the alkyl group. Examples of such epox~
compounds are 1,2-epoxyoctane, 1,2-epoxydodecane;
1,2-epoxyhexadecane, l, -epoxytetracosane and the like. Other , - - . . :, .:~ , ,: :.:

long chain epoxy compounds are glycidyl ethers of aliphatic alcohols wherein the aliphatic alcohols contain about 5 to about 25 carbon a~oms. Examples of such glycidyl ethers are the glycidyl ethers of amyl alcohol, hexanol, octanol, lauryl alcohol, stearyl alcohol, lignoceryl alcohol and the like.
Examples of useful alkyl hal~des are octyl chloride, decyl bromide, dodecyl iodine, hexadecyl bromide and the like.
The alkaline catalysts used in this invention are alkali metal hydroxides, e.g., sodium or potassium hydroxide.
In carrying out the process of this invention, the guar splits are added to a reactor along with water and the alkaline catalysts. Suffic7ent water is added to be imbibed by the splits and to swell them, but insufficient to dissol~e the splits. It is impor~ant that the guar splits retain their particulate form and to not merge together to form a gelatinous mass. The amount of wa.e~ added to the reactor will vary from about 30 to about ~50 par_s b~ welght of water to 100 parts by weiaht of guar.
Preferably, this amount of water will be about 75 to about 1 parts of ~-ater to 100 parta of guar.
The alka i metal hydrox~de is used in catalytic amounts, or if an aikyl halide is used, in amounts equivalent to the halide plus a catal"tic amount. The catalytis amount of alkali meta' hydroxide used is about 1 part up to about 50 parts by weight pe~
100 parts by weight of guar splits, and preferably about 3 to about 10 parts per 100 parts of guar.

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The alkaline catalyst is used in the process of this invention as an aqueous solution. It can be added as a solid to the reactor and dissolved in the water used in the process prior to the add~tion of the guar splits. Preferably, it is added to the reactor as an aqueous solution.
Air is then evacuated from the reactor and is replaced with an inert gas, e.g., nitrogen. A low shear mixing or tumbling type of agitation is used throughout the derivatizing reactions so as to contlnually expose the surfaces of the guar particles to the derivatizing agent and to keep a uniform temperature throughout the reactor without exerting shearing forces on the particles so as to grind or smear them.
The hydrophilic derivatizing agent is then introduced into the reactor and the temperature is controlled between about 100F
to about 250F, preferably about 160 to abut 200F.
The hydroph~lic derivatiz ng agent is used in an amount sufficien~ to obtain the M.S. speci'ied hereinbefore, i.e., about 0.2 to about 2 and preferably, about 0.3 to about 1.2. The amount of de_ivatlzing agent to be used c~n readily be deter~ined by those skilled in the art by running controlled experiments and analyzing the product. Generally the amount of de_ivatiz~ng agent w ll var~ from about 20 to about 350 parts of hydrophllic derivatizing agent to 100 parts by weight of guar and preferably about 25 to about 100 parts by weight.
The reaction with the hydrophilic derivatizing agent is conducted for a time sufficient to obtain the desired M.S., ;
: ` . . .

---` 2023324 generally about 30 minutes to about 3 hours.
When the hydrophilic derivatizing reaction is completed, the reaction with the hydrophcbic derivatizing agent is then conducted without isolating the product of the first reaction.
The hydrophobic derivatizing agent is added to the reactor as a solution in an organic solvent, wherein the solvent is or.e which can swell but not dissolve the guar derivative. The solvent is one which is miscible with the hydrophob_c derivatizing agent, wh,ch is miscible with water in the amount of at least 10 weight percent water-in-solvent or solvent-in-~-ater, and which has a solubility parameter greater than 4.5 (J~m3)1'2 x . Solubility parameter is described in detall in Kirk-Othmer, "Encyclopedia of Chemical Technology," 3rd Editicn, Volume 21 (1983~ beginn'ng at page 377, wh_ch is here_y incorporated by reference. Examples of suitable solvents a_-, l-propanol, 2-propancl, t-butanol, propvlene ox-de, tetrahydrofuran, dimethyl sulfoxlde, N,N-d~met~yl formam_~e.
methanoi, ethanol, ethylene glycol, ethylene glvcol monome~
ethe~, ethylene glycol mcnobutyl ether, propylene g'-yco:, propylene g'ycol monomethyl ether, propylene gl co mcnceth;l ether, diethylene glycol monoethyl ether, methyl ethyl ke~one, and acetone. Preferred solvents are the solvents which conta~n an aliphatic hydroxyl group, with the more preferred be~`ng secondary or tertia_y hydroxyl groups. The most prefer~e~
solvent is 2-propa~ol~ The amount of solvent used is at leas~
equal to the weight of the hydrophobic derivatizing agent, up to ' ' " :' , .

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about 10 times its weight, preferably about 2 to about 5 times its weight.
The amount of hydrophobic derivatizins agent used is that amount which produces a M.S. as referred to hereinbefore, i.e., about 0.001 to about 0.2. The amount of hydrophobic derivatiz ng agent to be used can be determined readlly by those skilled in the art by running controlled experiments and analyzing the product. Generally, the amount of derivatizing agent will vary from about 1 to about 50 parts by weight based on 100 parts by weight of guar splits originally reacted, and, preferably about 5 to about 20 parts by weiqht.
The reaction w-th the hydrophobic derivatizing agent is conducted at a temperature of about 100F to about 250F, preferably, about 160F to about 200F for a sufficient time to complete the reaction, generally about 1 to about 4 hours~
The hydrophilic, hydrophobic guar derivative still in par~icu'a e ~crm is washed wl_h water, to remove q'ycol by-producls, alkali metal hydrox des, organ c solvents and salts wn le remc~_ng a minimum of the derivatized guar. The wash ns c~n be conducted by siurrylng and decant ng, or bv counter-current extraction, processes well known to those sk lled in the art. The excess water s removed, e.g., by centrifugation, and the product is then dried to a moisture content below 15 weight percent, preferably below 10 weight percent. ~he drying processes can be conducted with a drum dryer, a hammer mill using heated alr, or n an oven followed 'ay , . . . ~ ,.

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grinding. A preferred method is "flash grinding~ whereby as the product is ground, the moisture is evaporated. The water can also be removed using organic solvents, such as those described hereinabove for use in the hydrophobic derivatization. The derivatized guar product is ground to a particle size of less than about 20 mesh (U.S. Standard Seive~ and, preferably less than about 80 mesh.
In carrying out the process, small amounts of borax or aluminum salts can be used to complex the surface of the guar particles, thereby facilitating the washing and drying processes which are well known to those skilled in the art.
The follow_ng examples describe the invention in detail.
Parts and percentages are by weight unless otherwise designated.
Example 1 To a suitable reactor were added 1800 parts of deionized water, 200 parts of a 50 percent aqueous solution of sod-um hydrox de an~ 5 par~s of borax. Agitation was begun and the temperat:lre ~as raised to 180F. Doubie pur'ried guar spl._s, 2000 parts, were then added and the reactor was evacuated and purged three times w~th nitrogen. A vacuum of -10 inches of Hg was applied, and introduction of 1500 parts of propylene oxide was begun and continue~ over a period of 1 hour and 30 mlnu~es while keeping the temperature at 170-176C. The temperature W39 then lowered to 85~F and a vacuum of -5 inches of Hg was applied.
A solution of ,00 parts of 1,2-epoxyhexadecane in 500 par_s or propylene oxide was added and held at 85F for 1 hour. Heat was .

- 202332~

then applied raising the temperature to 170 F. This temperature was held for 2 hours. Borax, 10 parts, in water, 250 parts, was added and the temperature was lowered to 110F. The reaction mass was discharged from the reactor.
The discharged product was washed twice with water (10 parts to 1 part of guar originally added to the reactor) and was centrifuged to a ~oisture content of 66.9 percent. The product was then dried and processed through a hammer mill at an air inlet temperature of 550F, outlet air of 275 F. The resulting product had a moisture content of 7.8 percent and an average particie s ze of less than 150 (U.S. Standard Sieve).

To a suitable reactor were added 1800 parts of deionized water, 300 parts of 50 percent aqueous sodium hydroxide, and 7 parts of borax. Heat was applied rais~ng the temperature to 180F. DOUD'e purified guar splits, 2000 parts, were then added.
The reactor was e~acuated and purged three times with nitrogen, the temperature was adjusted to 140F, and a vacuum of -10 nches of Hg was appl_ed. The addition of 1500 parts of propy'ene ox-de was begun and tne temperature wa3 raised to 180F. The add_tion of propylene ox_de was completed in 1 hour and 52 minutes. The tempera~ure was then lowered to 140F and a solution of 150 parts of l,.-epoY~yhexadecane in 500 parts of lsopropanol was added.
~fter 30 mlnutes at 140F, the temperature was raised to l~OaF
and was held at this temperature for 2 hours. The temperature was lowered to 110F and the reaction mass was discharged from the reactor.

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2~23324 The reaction mass was washed twice with water (10:1 by weight) and was centrifuged to a moisture content of 66.8 percent. The product was then milled and dried in a hammer mill with an ai~ inlet temperature of 480F and an outlet temperature of 240F. The product had a moisture content of 6.7 percent and an average particle size of less than 150 mesh (U.S. Standar~
Sieve).
Example 3 Using the same procedure described in Example 2, a reaction was conducted with 2000 parts of double pur fied guar splits, 1800 parts of deionized water, 300 parts of 50 percent aqueous sod~um hydrox de, 7 parts of borax and 1500 parts of propylene oxide, foilowed by reaction with 150 parts of i,2-epoxydecane in 500 par's of _sopropanol. The resulting product had a moisture content of 5.6 percent and an average particle si2e of less than 150 mesh.
Exampie 4 To a su table reactor were added 1760 parts of deionized water, 168 parts of a 50 percent aqueous sodium h~drox_de solution and ~ parts of borax. The temperature was ra.sed '~
180F and 2000 parts of double purified splits were added. The reactor was evacuated and purged 3 times with nitrogen ar.d nitrogen was added to a pressure of 10 psig. A~ter holding the pressure for 10 minutes, the temperature was adjusted to lfiO~
and the reactor was evacuated to -10 in hg. The addition o~ i60 parts of butylene oxide was begun and continuing over 1 hour and . `' ' ' ' ' ' ' ~ ~': ~' , ~ ~ .

30 minutes with the temperature rising from 161 F to 178F. The temperature was lowered to 140F, at which point a solution of 150 parts of l-epoxyhexadecane in 500 parts of isopropanol was added. After holding at 140 F for 30 minutes, the temperature was raised to 170F and was held for 2 hours. The temperature was then lowered to 78 F. The product was discharged from the reactor and was washed twice with water at 10 to 1 water to initial guar ratio. The washed product was centrifuged to a moisture content of 68.4 percent and was then milled using inlet air of 550F. The resultlng product had a moisture content of 8.9 percent and an average mesh size of less than 150 (U.S.
Standard Sieve~.
Example 5 Half percent so'utions of the derivatized guar from rxamples 1 to 4 were made in deicn zed water. The p~ of the solutions was adjus,ed to 6.~ w~th hydrochloric acid. The solutions were stirr2d for one hour. To 400 parts cf each solution were added a 28 percent solution of ammonium lauryl sulfate (AL~ in wa'er.
The viscosity was then determined uslng a Brockfield viscometer at 20 RPM. After each viscosity determination, addi~ona' ammonium lauryl sulfate was added and the viscosity was determlned after each addition~ The viscosity determination and the amount of ammonium lauryl sulfate are shown in the ~able.

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Table Example 1 2 3 4 ALS - partVISC V_Sf VISC V SC
cps cps cps cps 0.2 1400 0.4 300 2300 1032 O.S 300 0.8 1250 4300 4 05 1.0 960 5700 700 6210 1.2 720 1.25 6600 1.4 8320 1,5 10,0007920 l.fi 1.75 ~10,~00 2.. 1>10,000 491 2.~5 >10,000 2.5 >10,0~0 2.75 28~0 3.0 lcOO 5000 3.5 700 i. ; ., . . , . ~ : -: . - - , ~ . ~
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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. Var ations and changes may be made by those skilled in the art without departing from the spirit of the invention.

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Claims (5)

1. A process for preparing guar gum derivatives having both hydrophilic ether substituents and hydrophobic ether substituents wherein the hydrophilic ether substituents are selected from at least one member of the group consisting of RO-and HOR1O-, wherein R is an alkyl group containing one to four carbon atoms, and R1 is an alkylene group containing two to four carbon atoms having the OH group on the carbon atom beta to the ether group, wherein the hydrophobic substituents are selected from at least one member of the group consisting of R2O-, HOR3O-, and wherein R2 is an alkyl group containing about 8 to about 28 carbon atoms, wherein R3 is an alkylene group containing about 8 to about 28 carbon atoms having the OH group on the carbon atom beta to the ether group, and wherein R4 is an alkyl group containing about 5 to about 25 carbon atoms which comprises:

a) reacting guar splits in an aqueous alkaline medium, wherein sufticient water is present to swell the guar splits but not to dissolve them, with a hydrophilic derivatizing agent selected from at least one member of the group consisting of alkyl halides, RX, and 1,2-alkylene oxides, R1=O, in an amount sufficient to obtain a M.S. of about 0.2 to about 2, b) without isolation, reacting the hydrophilically derivatized guar splits with a hydrophobic derivatizing agent selected from at least one member of the group consisting of alkyl halides, R2X, long chain 1,2-epoxides, R3=O, and long chain glycidyl ethers, wherein the hydrophobic derivatizing agent is added as a solution in an at least partially water miscible organic solvent capable of swelling the guar splits but not dissolving them and wherein the hydrophobic derivatizing agent is present in an amount sufficient to obtain a M.S. of about 0.001 to about 0.2.

c) washing the product, and d) drying and grinding it to a moisture content below 15 weight percent and a particle size below about 80 mesh (U.S.
Standard Sieve).

2. The process of Claim 1 wherein the water in (a) is present in tne amount of about 30 to about 250 parts by weight to 100 parts by weight of the guar splits, wherein the alkaline medium is obtained from an alkali metal hydroxide in the amount of about 1 to about 50 parts by weight per 100 parts by weight of guar, and wherein the (a) reaction is conducted at a temperature of about 100°F to about 250°F.

3. The process of Claim 2 wherein the water is present in the amount of about 75 to about 125 parts by weight, the alkali metal hydroxide is sodium hydroxide in the amount of about 3 to about 10 parts, and the temperature is about 160°F to about 200°F.

4. The process of Claim 1 wherein the solvent in (b) is miscible with water in the amount of at least 10 weight percent water-in-solvent or solvent-in-water and having a solubility parameter greater than 4.5 (J/m3) 1/2 x 10-3, wherein the solvent is used in an amount at least equal to the weight of hydrophobic derivatizing agent up to about 10 times its weight, and wherein the (b) reaction is conducted at a temperatures of about 100°F to about 250°F.

5. The process of Claim 4 wherein the solvent is isopropanol in the amount of about 2 to about 5 times the weight of hydrophobic derivatizing agent and the temperature is about 100°F to about 200°F.