GB1602187A

GB1602187A - Method of increasing the viscosity of liquid organic systems and organophilic clay having enhanced dispersibility therein

Info

Publication number: GB1602187A
Application number: GB49913/77A
Authority: GB
Original assignee: NL Industries Inc
Current assignee: NL Industries Inc
Priority date: 1977-11-30
Filing date: 1977-11-30
Publication date: 1981-11-11

Description

(54) METHOD OF INCREASING THE VISCOSITY OF LIQUID ORGANIC SYSTEMS AND ORGANOPHILIC CLAY HAVING ENHANCED DISPERSIBILITY THEREIN (71) We, NL INDUSTRIES INC.. a Company organized under the laws of the State of New Jersey, United States of America of 1221 Avenue of the Americas, New York, New York 10020. U.S.A. do hereby declare the invention. for which we pray that a Patent may be granted to us. and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the use of organophilic organic-clay complexes in organic liquid systems. Dispersion of such complexes in the organic liquid systems leads to the formation of a gel therein. Depending on the composition of the gel, such gels may be useful as lubricating greases, oil base drilling fluids such as oil base muds and oil base packer fluids, paint-varnish-lacquer removers, paints, foundry moulding sand binders and the like.

It is well known that organic compounds which contain a cation will react under favourable conditions bv ion-exchange with clays which contain a negative layer-lattice and exchangable cations to form organophilic organic-clay products. If the organic cation contains at least one alkyl group containing at least 10 carbon atoms, then such organoclays have the property of swelling in certain organic liquids.

Since the commercial introduction of organoclays in the early 1950's, e.g. those sold under the Trade Mark BENTONE, it has becomme well known to gain the maximum gelling (thickening) efficiency from these organoclays by adding a low molecular weight polar organic material to the composition. Such polar organic materials have been variously called dispersants. dispersion aids. solvating agents. dispersion agents and the like.

It is disclosed in the U.S. Patent No. 3,753,906 that water is a dispersant when used in a heated grease preparation process. U.S. Patent 3.654.171 however, discloses that water is not a dispersant in grease preparation processes conducted at a temperature ranging from ambient to about 39()OF (t04.44C). These polar materials may affect properties other than the viscosity or gel strength of the organic gels. such as mechanical stability, thixotropy and storage stabilitv.

The most efficient and accepted polar materials for use as dispersants have been found to be low molecular weight alcohols and ketones, particularly methanol and acetone. These dispersants. however. have verv low flash points and require the use of flame-proof apparatus. Higher boiling. high flash point dispersants may be used but these are less efficient and often produce gels having poor secondary properties such as mechanical stability or storage stabilitv.

U.S. Patent No. 3.537.994 discloses the use of organophilic clays prepared from a side varietv of ammonium compounds. including methyl benzyl dihexadecyl ammonium compounds, as gellants for lubricating greases. All of the examples in this patent disclose the use of a polar organic dispersant for the organophilic clay in the preparation of the greases.

Accordingly. there is a need for an organophilic clay gellant which is easy to disperse in organic systems and which requires no dispersant. other than perhaps minor quantities of water. for gelling organic systems. There is also a need for a process of increasing the viscosity of organic systems with organophilic clay gellants in the absence of polar organic dispersants for the gellant.

The present invention accordingly provides a method of increasing the viscosity of a liquid organic system which method comprises mixing with the liquid organic system an effective amount of an organophilic clay gellant, which is the reaction product of a methyl benzyl dialkyl ammonium compound wherein the alkyl groups independently each have from 14 to 20 carbon atoms, and a smectite -type clay having a cation exchange capacity of at least 75 milli-equivalents per 100 grams of clay, wherein no polar organic dispersant for the organophilic clay gellant is added to the organic system.

The invention includes an organophilic clay gellant comprising the reaction product of a smectite-type clay, having a cation exchange capacity of at least 75 milli-equivalents per 100 grams of clay. and a methyl benzyl dialkyl ammonium compound, the alkyl groups each independently having from 14 to 20 carbon atoms, and wherein the amount of ammonium compound in the gellant being at least 87.5 millequivalents per 100 grams of clay on a 100% active clay basis.

In the method of the invention the liquid organic system may include water typically in am amount of up to 1% preferably 0.1 to 0.5% by weight.

The invention further includes an oil base drilling fluid comprising a water-in-oil emulsion and a thickening amount of an organophilic clay gellant which is the reaction product of a methyl benzyl dialkyl ammonium compound in which the alkyl groups independently each have from 14 to 20 carbon atoms, and a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay.

The clays used to prepare the organoclay thickeners used in this invention are smectite-type clays which have a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay. Particularly desirable types of clay are the naturally occurring Wyoming variety of swelling bentonite and similar clays and hectorite, a swelling magnesium-lithium silicate clay.

The clays, especially the bentonite-type clays, are preferably converted to the sodium form if the are not already in this form. This can conveniently be done by preparing an aqueous clay slurry and passing the slurry through a bed of cation exchange resin in the sodium form. Alternatively, the clay can be mixed with water and a soluble compound such as sodium carbonate, sodium hydroxide etc.. and shearing the mixture such as with a pugmill or extruder.

Smectite-type clays prepared synthetically be either a pneumatolytic or, preferably, a hydrothermal synthesis process can also be used to prepare these novel organic-clay complexes. Representative of such clays are the following: Montmorillonite [Al4-xMgx) Si8O20(OH)4-fFf]x R+ where 0.55 # x #1.10, f # 4 and R is Na, Li, NH4 or a mixture thereof; Bentonite [Al4-xMgx) Si8-yAly)O20(OH)4-fFf] (x+y) R+ where 0 < x < 1.10, 0 < y < 1.10, 0.55 # (x+y) # 1.10, f # 4 and R is Na, Li, NH4 or a mixture thereof; Beidellite [(Al4+y)(Si8-x-yAlx+y)O20(OH)4-fFf]x R+, where 0.55 # x # 1.10, 0 # y # 0.44, f # 4 and R is Na, Li, NH4 or a mixture thereof; Hectorite [(Mg6-xLix)Si8O20(OH)4Ff]x R+ where 0.57 # x # 1.15, f # 4 and R is Na. Li, NH4 or a mixture thereof; Saponite [(Mg6-yAly)(Si8-x-yAlx+y)O20(OH)4-fFf]x R+ where 0.58 # x # 1.18, 0 # y # 0.66, f # 4 and R is Na, Li, NH4 or a mixture thereof; Stevensite [Mg6~X) Si8O20 (OH)4~fFf] 2 x R+ where 0.28 # x # 0.57, f # 4 and R is Na, Li. NH4 or a mixture thereof.

These clays may be synthesized hydrothermally by forming an aqueous reaction mixture in the form of a slurry containing mixed hydrous oxides or hydroxides of the desired metals with or without sodium (or alternate exchangeable cation or mixture thereof), fluoride in the proportions defined by the above formulae and the pre-selected values of x,y and f for the particular synthetic smectite desired. The slurry is then placed in an autoclave and heated under autogeneous pressure to a temperature within the range of approximately 100 to 325 C, preferably 275 to 300 C, for a sufficient period of time to form the desired product. Formulation times of 3 to 48 hours are typical at 300 C, depending on the particular smectite being synthesized, and the optimum time can readily be determined by pilot trials.

The cation exchange capacity of the smectite clay can be determined by the well-known ammonium acetate method.

The organic compounds used in the method of this invention are quaternary ammonium salts containing one methyl, one benzyl and two alkyl radicals, in each case the alkyl radiccls each independently containing from 14 to 20 carbon atoms. Preferably the alkyl radicals have from 16 to 18 more preferably 16 to 18 carbon atoms each. It is also preferred that the quaternary ammonium salts contain a mixture of alkyl radicals having from 14 to 20 carbon atoms and particularly preferred where 20 to 35% have 16 carbon atoms and 60 to 75CHo have 18 carbon atoms, 100% basis. It is particularly preferred that the said alkyl groups are hydrogenated tallow radicals which typically have the formula CnH2n+l, where n is 16 or 18.

The salt anion is preferably at least one of chloride, bromide, acetate, hydroxide and nitrite although other anions may be used. (For convenience and brevity we include hydroxide as a salt anion" although commonly hydroxides and not considered as salts.) Bromide and especially chloride are more preferred anions. Particularly preferred methyl benzyl dialkyl ammonium salts may be represented by the formula:

where R, is CH3. R2 is C6H5CH2, R3 and R4 are alkyl groups containing a mixture of 14 to 20 carbon atoms wherein 20 to 35% have 16 carbon atoms and 60 to 75% have 18 carbon atoms. based on 100% and where M- is preferably one or more of Cl-, Br-, NO2-, OH and CH3COO-.

The preferred quaternary ammonium salt for use in the practise of this invention is methyl benzyl dihydrogenated tallow ammonium chloride. Commercially prepared hydrogenated tallow typically analyzes 2.0% C14, 0.5% C15, 29.0% C16, 1.5% C17, 66.0% C1x, and 1.0%' C21 alkyl radicals.

The alkyl radicals may be derived from other natural oils including various vegetable oils, such as corn oil, soybean oil, cottonseed oil, castor oil and other similar oils and various animal oils or fats. The alkyl radicals may be petrochemically derived such as from alpha olefins.

Many processes are known to prepare the ammonium compounds used in the present invention. Thus a tvpical synthesis of methyl benzyl dialkyl ammonium salts includes the preparation of dialkvl secondary amine, for example, by the hydrogenation of a suitable nitrile. form the methyl dialkyl tertiary amine by reductive alkylation using formaldehyde as the source of methyl radical and thereafter form the quaternary amine halide by adding benzyl chloride or benzyl bromide to the tertiary amine. Analogous methods can be used for the other quaternary ammonium salts.

The invention includes a modification of the method of the invention in which the organophilic clay gellant is the reaction product between a methyl trihydrogenated tallow or a benzyl trihydrogenated tallow ammonium compound and a said smectite-type clay and a modification of the gellant of the invention in which the ammonium compound is a methyl trihydrogenated tallow or a benzyl trihydrogenated tallow ammonium compound and specifically in this modification are included methyl trihydrogenated tallow ammonium hectorite and benzyl trihydrogenated tallow ammonium hectorite. In these modifications the clay may, typically. be hectorite and the range of milliequivalent ratios is typically from 95.5 to 119.9 The organophilic clays of this invention can be prepared by admixing the clay, methyl benzyl dialkyl ammonium compound and water together. preferably at a temperature within the range from 100OF (38"C) to 180OF (82"C), more preferably 140OF (60"C) to 170OF (77"C) for a period of time sufficient for the organic compound to coat the clay particles, followed by filtering. washing drying and grinding. In using the organophilic clays in emulsions, the drying and grinding steps may be eliminaated. When admixing the clay, quaternary ammonium compound and water together in such concentrations that a slurry is not formed, then the filtration and washing steps can be eliminated.

Preferably the clay is dispersed in water at a concentration from about 3 to 7%, the slurry optionally centrifuged to remove non-clay impurities which constitute typically from 10 to about 50% of the starting clay composition, the slurry agitated and heated to a temperature in the range from 140OF (60"C) to 170OF (77"C) the quaternary amine salt added in the desired milliequivalent ratio, preferably as a liquid in isopropanol or dispersed in water and the agitation continued to effect the reaction.

The amount of the ammonium salt added to the clay for purposes of this invention must be sufficient to impart to the organophilic clay the enhanced dispersion characteristics desired. The milliequivalent ratio (M.E. ratio) is defined as the number of milli-equivalents of the organic compound in the organoclay per 100 grams of clay, 100% active clay basis.

The organophilic clays used in the method of this invention typically have a M.E. ratio of at least 87.5. Preferably they have a M.E. ratio of from 100 to 120. At lower M.E. ratios the organophilic clays produced tend to be ineffective gellants even though they may be good gellants when dispersed in a conventional manner with polar organic dispersants, etc. At higher milliequivalent ratios the organophilic clays tend to be poor gellants. However, it will be recognized that the optimum M.E. ratio even within the range from 100 to 120 will vary depending on the characteristics of the organic system to be gelled by the organophilic clay.

A simple convenient test has been devised to illustrate the enhanced dispersion characteristics of the organophilic clays utilized in this invention and the results obtained in utilizing the composition of this invention. The test is conducted by mixing the organophilic clay with a conventionally refined low VI oil at a concentration of 4.5% by weight for 0.5 minutes using a Fisher Scientific Co. DYNA-MIX (Registered Trade Mark) mixer operating at 1800 rpm. The viscosity of the oil-gellant mixture is then obtained. Longer mixing times may be undertaken. Thereafter, 0.12% water is added to the mixture and the mixing is continued. The viscosity of the mixture is periodically determined, generally after 6-9 minutes. A Brookfield RVT Viscometer is used to obtain the viscosity although any suitable viscometer can be used. Under these low shear conditions in the absence of a polar organic dispersion aid the much greater dispersibility of the organophilic clays of this invention as compared to previously known organophilic clays can be readily demonstrated.

Generally. the organophilic clays prepared from approximately 100% active clay (containing essentially no impurities) will produce a gel having a 10 rpm Brookfield viscositv of at least 20.000 centipoises when dispersed at a concentration of 4.5% in a hydrocarbon oil having a viscosity index less than about 20 with a mixer operating at 1800 rpm for 6 minutes in the presence of 0.1 - 0.59 added water.

The process of this invention can be carried out at elevated temperatures. However, it is preferred that the process be conducted at temperatures less than 85"C, more preferably at ambient temperatures.

The following Examples illustrate the composition of this invention and its use as a gellant.

The smectite clays used are hectorite and Wyoming bentonite. The hectorite clay was slurried in water and centrifuged to remove substantially all of the non-clay impurities. The Wyoming bentonite clay was slurried in water, centrifuged to remove substantially all of the non-clay impurities and ion-exchanged to the sodium form by passing the slurry through a bed of cation exchange resin in the sodium form. Several samples of methyl benzyl dihydrogenated tallow ammonium chloride supplied by ENENCO Inc. were used to prepare organoclays in the Examples. The molecular weight of these samples ranged from 619 to 644 and the percent activity in isopropanol varied from 60% to 81.5%.

The conventionally refined oil and the solvent refined oils had the following properties: Conventionally Solvent refined refined Gravity, "API at 60 F 20 30.4 Viscosity, SUS at 100 F 500 400 Viscosity, SUS at 210 F 53 58 Viscosity Index 12 98 Index of Refraction 1.5085 1.4811 Flash Point. "F 390 460 Pour Point, "F -5 5 Example 1 The organophilic clays listed in Table A were prepared by heating the clay slurry to a temperature within the range from 150 F (66"C) to 1700F (77"C), adding while stirring the clay slurry, the indicated amount of the indicated quaternary ammonium chloride which had been previously melted for convenience in handling, and continuing the stirring for approximately 45 minutes, followed by filtering, washing, drying at 1400F (60"C) and grinding.

These organophilic clays were evaluated in the conventionally refined oil in the ease of dispersion test described which dramatically indicates the improved ease of dispersion of these thickeners as compared to similar organophilic clay thickeners.

The data in Table A indicates the sharp increase in the ease of dispersion of organophilic clays prepared from methyl benzyl dihydrogenated tallow ammonium chloride and the smectite-type clays when the amount of this quaternary ammonium compound was in the range of 100 to 120 miliequivalents per 100 grams of clay. The data also illustrates the much superior dispersion characteristics of the preferred organophilic clays as compared with organophilic clays prepared from somewhat similar but different quaternary ammonium compounds.

Example 2 Various types of the organophilic clay gellants prepared in Example 1 were evaluated as grease thickeners at a concentration of 6% by weight in the conventionally refined oil in the presence of 0.1% and 0.3% water. The greases were prepared by mixing the gellant, oil and water together for thirty minutes using a drill press equipped with pitched sweep blades rotating at 450 rpm. The,resulting batch was then milled through a Tri-Homm disperser with a rotor to stator clearance of 0.01 inch. The ASTM penetrations of the greases, after setting overnight. were obtained after working the greases 60 and 10,000 strokes in an ASTM motorized grease worker assembly. The data obtained are given in Table B. These gellants were also evaluated in a conventional heated grease preparation processes utilizing 4% by weight acetone as a polar organic dispersant for the gellant. The greases were prepared by mixing the gellant, oil and acetone together for 30 minutes, heating to 250 F.

(121) C.) with continued mixing to drive off the acetone, cooling to 180 F. (82 C.) and adding 0.1 CTe water with continued mixing and milling as above. The data obtained for these greases, which are not an illustration of this invention, are compared with the data for the greases in Table B since these greases have the same composition.

The data indicates that the organophilic clays containing an amount of methyl benzyl dihydrogenated tallow ammonium cation in excess of 100 milliequivalents per 100 grams of clay were very efficient thickeners for this oil at ambiint temperatures using only a small modicum of water as the dispersant. The data also indicates that the organophilic clays having milliequivalent ratios in excess of 100 disperse readily in the absence of a polar organic dispersant to produce greases having a penetration ("yield" or viscosity) which is equivalent to that obtained for the greases prepared with the dispersant, whereas at lower milliequivalent ratios the organophilic clays produce greases which are definitely inferior to the greases prepared with the dispersant.

Example 3 The organophilic clay of Examples 1 and 2 prepared from hectorite reacted with 108 milliequivalents/100 grams of clay of methyl benzyl dihydrogenated tallow ammonium chloride was evaluated as a grease gellant in the same manner as in Example 2 except that the concentration of water was varied from 0% to 0.4%. The ASTM penetrations after working the grease 60 and 10.000 strokes were as follows: C)Ce water - 259, 259: 0.1Xc water - 236, 264; 0.2% water - 230, 275; 0.3% water - 214, 250; 0.4% water - 243, 275.

Example 4 A hectorite clay containing 106.8 milliequivalents methyl benzyl dihydrogenated tallow ammonium cation and bentonite clay containing 102.6 milliequivalents methyl benzyl dihydrogenated tallow ammonium cation were evaluated as gellants at a concentration of 5% in the conventionally refined oil in the presence of 0.2% water. These organophilic clays were evaluated in a similar manner in the presence of 2% acetone as a dispersant for the organophilic clays. The greases were prepared by mixing the gellant, oil and either water or acetone together for 30 minutes using the drill press as in Example 2, and milling the pre-gels obtained as in Example 2. The greases were evaluated as in Example 2. The data obtained are given in Table C.

The data indicates that the greases prepared containing only 0.2% water had a much lower penetration (higher grease "yield" or viscosity) than the greases containing the polar organic dispersant prepared by the prior art process.

Example 5 Various organophilic clays were prepared using the procedures given in Example 1 from sodium bentonite and the indicated milliequivalent ratios of metyl benzyl dihydrogenated tallow ammonium chloride. These organophilic clays were evaluated as thickeners for the conventionally refined oil and the solvent refined oil using the procedures given in Example 2. The data obtained are given in Table D.

The data indicates that the preferred concentration of the quaternary ammonium compound is from 100 miliequivalents to 120 milliequivalents per 100 grams of clay.

Example 6 The 102.6 milliequivalent ratio bentonite clay thickener of Example 1 was evaluated as a thickener/suspending agent in an invert emulsion (water-in-oil) drilling fluid at a concentration of 4 pounds per barrel (42 gallons). The drilling fluid had the following composition: 154 parts diesel oil, 129 parts water, 68 parts calcium chloride, 8 parts DURATONE HT, fluid loss control additive, 15 parts INVERMUL emulsifier, and 2 Parts E-Z MUL emulsifier. Standard rheology data were obtained on the drilling fluids after mixing with the organophilic clay for 15 minutes with a multimixer. The results given in Table E indicate that this organophilic clay is an excellent thickener for invert emulsion drilling fluids.

The examples indicate the remarkable results achieved utilizing the process of this invention, namely, that the vicosity of liquid organic systems is efficiently increased with an organophilic clay gellant in the absence of a polar organic dispersant for the gellant. Indeed, it is preferred that the viscosity of the organic system obtained by the process of this invention is at least equal to the viscosity which would be obtained if the organic system contained an effective dispersing amount of a polar organic dispersant for the gellant. This can be achieved for any particular organic system by adjusting the milliequivalent ratio of the organophilic clay gellant to the optimum value for that system within the range of 100 to 120.

TABLE A 4.5% Organophilic Clay Organophilic Clay 10 rpm Brookfield Viscosity, cp.

ME 0% Water 0.12% Water Quaternary Ammonium Chloride Clay Ratio 0.5 Minutes 6 Minutes 9 Minutes Methyl benzyl dihydrogenated tallow Hectorite 87.5 480 - - -(2) 1,000 Methyl benzyl dihydrogenated tallow Hectorite 92.4 480 - - - 2,000 Methyl benzyl dihydrogenated tallow Hectorite 97.2 560 - - - 9,000 Methyl benzyl dihydrogenated tallow Hectorite 99.1 560 - - - 11,200 Methyl benzyl dihydrogenated tallow Hectorite 99.7 - - - 11,200 - - Methyl benzyl dihydrogenated tallow Hectorite 103.8 7,000 48,400 58,400 Methyl benzyl dihydrogenated tallow Hectorite 104.3 - - - 35,200 50,000 Methyl benzyl dihydrogenated tallow Hectorite 106.5 6,720 48,000 - - Methyl benzyl dihydrogenated tallow Hectorite 108.0 2,040 49,600 64,400 Methyl benzyl dihydrogenated tallow Hectorite 110.5 1,040 33,000 46,800 Methyl benzyl dihydrogenated tallow Hectorite 112.9 890 44,000 67,600 Methyl benzyl dihydrogenated tallow Hectorite 115.0 3,400 33,600 34,800 Methyl benzyl dihydrogenated tallow Hectorite 117.9 - - - 21,000 - - Methyl benzyl dihydrogenated tallow Hectorite 124.9 - - - 13,000 - - Methyl benzyl dihydrogenated tallow Bentonite 91.5 400 400 - - Methyl benzyl dihydrogenated tallow Bentonite 96.9 - - - 3,200 - - Methyl benzyl dihydrogenated tallow Bentonite 102.6 2,880 36,800 44,000 Methyl benzyl dihydrogenated tallow Bentonite 106.0 9,280 51,200 50,000 Methyl benzyl dihydrogenated tallow Bentonite 111.0 20,000 30,400 25,000 Methyl benzyl dihydrogenated tallow Bentonite 114.4 - - - 15,500 - - Methyl benzyl dihydrogenated tallow Bentonite 120 - - - 14,600 - - Methyl benzyl dihydrogenated tallow Bentonite 123.6 - - - 6,800 - - Dimethyl dihydrogenated tallow Hectorite 95.2 - - - 3,400 - - Dimethyl dihydrogenated tallow Hectorite 102.9 - - - 3,400 - - Dimethyl dihydrogenated tallow Hectorite 108.8 480 12,500 - - Dimethyl dihydrogenated tallow Hectorite 117.0 440 440 - - - TABLE A (CONT.) 4.5% Organophilic Clay Organophilic Clay 10 rpm Brookfield Viscosity, cp.

ME 0% Water 0.12% Water Quaternary Ammonium Chloride Clay Ratio 0.5 Minutes 6 Minutes 9 Minutes Methyl trihydrogenated tallow Hectorite 95.8 - - - 4,800 - - Methyl trihydrogenated tallow Hectorite 101.9 - - - 4,400 - - Methyl trihydrogenated tallow Hectorite 108.5 640 3,320 - - Methyl trihydrogenated tallow Hectorite 118.5 - - - 7,400 - - Benzyl trihydrogenated tallow Hectorite 95.5 - - - 5,000 - - Benzyl trihydrogenated tallow Hectorite 101.4 - - - 4,800 - - Benzyl trihydrogenated tallow Hectorite 107.9 1,480 4,000 - - Benzyl trihydrogenated tallow Hectorite 119.9 - - - 5,600 - - Dimethyl benzyl hydrogenated tallow Hectorite 117 - - - - - - 560 Dimethyl benzyl hydrogenated tallow Bentonite 96.6 - - - 400 - - Dimethyl benzyl hydrogenated tallow Bentonite 101.9 - - - 200 - - Dimethyl benzyl hydrogenated tallow Bentonite 111.1 - - - 400 - - Dimethyl benzyl hydrogenated tallow Bentonite 120.5 - - - 400 - - Methyl benzyl dihydrogenated tallow (1) 111.0 8,800 41,600 42,800 (1) 1:1 weight ratio of hectorite and bentonite (2) - - - indicates the data was not obtained TABLE B Organophilic Clay Process of This Invention Prior Art Process ASTM Penetrations, mm x 10 (2) ASTM Penetrations, mm x 10 Quaternary Ammonium ME 0.1% Water 0.3% Water 0.1% Water Chloride Clay Ratio 60x 10,000x 60x 10,000x 60x 10,000x MB2HT (1) Hectorite 87.5 440+ - - - 402 433 345 367 MB2HT Hectorite 92.4 384 417 384 422 329 354 MB2HT Hectorite 97.2 334 350 320 363 278 304 MB2HT Hectorite 99.1 309 343 299 345 275 300 MB2HT Hectorite 103.8 252 285 245 294 245 267 MB2HT Hectorite 108.0 236 264 214 250 245 265 MB2HT Hectorite 112.9 262 301 262 321 292 318 (1) Methyl benzyl dihydrogenated tallow (2) Greases "too thin" to measure have penetrations greater than 440.

TABLE C 5% Gellant in a Conventionally Refined Oil Quaternary Ammonium ME % % ASTM Pene., mm x 10 Cation (1) Clay Ratio Water Acetone 60x 10,000x MB2HT Hectorite 106.8 0.2 0 285 321 MB2HT Hectorite 106.8 0 2.0 332 368 MB2Ht Bentonite 102.6 0.2 0 300 341 MB2HT Bentonite 102.6 0 2.0 328 362 (1) Methyl benzyl dihydrogenated tallow TABLE D ME % ASTM Penetrations, mm x 10 Oil Ratio Water 60x 10,000x Conventionally refined 87.9 0 373 390 Conventionally refined 96.7 0 344 373 Conventionally refined 100.3 0 299 345 Conventionally refined 105.9 0 275 336 Conventionally refined 114.5 0 345 382 Conventionally refined 120.3 0 410 415 Solvent refined 87.9 0.3 440+ - Solvent refined 96.7 0.3 440+ - Solvent refined 100.3 0.3 358 402 Solvent refined 105.9 0.3 305 342 Solvent refined 114.5 0.3 304 374 Solvent refined 120.3 0.3 347 390 TABLE E Drilling Fluid Rheological Characteristics Organo Fann Apparent Yield Gel Strength Bentonite Viscosity Viscosity Point Ib/100 ft Thickener 600 rpm 300 rpm cp. Ib/100 ft 10 sec. 10 min Example 1, 160 110 80.0 60 37 44 102.6 ME None 79 43 39.5 7 3 3

Claims

WHAT WE CLAIM IS:

1. A method of increasing the viscosity of a liquid organic system which method comprises mixing with the liquid organic system an effective amount of an organophilic clay gellant, which is the reaction product of a methyl benzyl dialkyl ammonium compound wherein the alkyl groups independently each have from 14 to 20 carbon atoms and a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay, wherein no polar organic dispersant for the organophilic clay gellant is added to the organic system.

2. A method as claimed in Claim 1 wherein the smectite-type clay is hectorite and/or sodium bentonite.

3. A method as claimed in either Claim 1 or Claim 2 wherein the amount of ammonium compound is at least 87.5 milliequivalents per 100 grams clay on a 100% active clay basis.

4. A method as claimed in Claim 3 wherein the amount of the ammonium compound is from 100 to 120 milliequivalents per 100 grams of clay on a 100% active clay basis.

5. A method as claimed in any one of Claims 1 to 4 wherein the smectite-type clay includes from 10 to 40% by weight of non-clay impurities.

6. A method as claimed in any one of claims 1 to 5 wherein the said alkyl groups in the ammonium compound each contain independently from 16 to 18 carbon atoms.

7. A method as claimed in any one of claims 1 to 6 wherein in the ammonium compound from 20 to 35cue of the said alkyl groups are of 16 carbon atoms and from 60 to 75% of the said alkyl groups are of 18 carbon atoms.

8. A method as claimed in any one of claims 1 to 7 wherein the ammonium compound is a methyl benzyl dihydrogenated tallow ammonium compound.

9. A method as claimed in claim 8 wherein the ammonium compound is in the form of the chloride salt.

10. A method as claimed in any one of claims 1 to 8 wherein the ammonium compound is in the form of a salt with at least one of Cl-, Br-, NO2-, OH and CH3CO2-.

11. A method as claimed in any one of claims 1 to 10 wherein from 0 to 1.0% by weight of water is mixed with the system.

12. A method as claimed in Claim 11 wherein the amount of water is from 0.1 to 0.5% by weight.

13. A method as claimed in any one of claims 1 to 12 and substantially as hereinbefore described.

14. An organophilic clay gellant comprising the reaction product of a smectite type clay, having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay, and a methyl benzyl dialkyl ammonium compound. the alkyl groups, each independently having from 14 to 20 carbon atoms, and the amount of ammonium compound in the gellant being at least 87.5 milliequivalents per 100 grams of clay in a 100% active clay basis.

15. A gellant as claimed in claim 14 wherein the smectite-type clay is hectorite and/or sodium bentonite.

16. A gellant as claimed in either claim 14 or claim 15 wherein the amount of the ammonium compound is from 100 to 120 milliequivalents per 100 grams of clay on a 100% active clay basis.

17. A gellant as claimed in any one of claims 14 to 16 wherein the smectite-type clay includes from 10 to 40% by weight of non-clay impurities.

18. A gellant as claimed in any one of claims 14 to 17 wherein the said alkyl groups in the ammonium compound each contain independently from 16 to 18 carbon atoms.

19. A gellant as claimed in any one of claims 14 to 17 wherein in the ammonium compound from 20 to 35chic of the said alkyl groups are of 16 carbon atoms and from 60 to 75% of the said alkyl groups are of 18 carbon atoms.

20. A gellant as claimed in any one of claims 14 to 18 wherein the ammonium compound is a methyl benzyl dihydrogenated tallow ammonium compound.

21. A gellant as claimed in claim 20 wherein the ammonium compound is in the form of the chloride salt.

22. A gellant as claimed in any one of claims 14 to 20 wherein the ammonium compound is in the form of a salt with at least one of Cl-, Br-, NO2-, OH-, and CH3CO2.

23. An organophilic clay gellant having enhanced dispersibility in organic systems comprising the reaction product of an ammonium compound having the formula:

wherein R1 is CH3, R2 is C6H5CH2, R3 and R4 are alkyl groups containing a mixture of 14 to 20 carbon atoms wherein 20 to 35% have 16 carbon atoms and 60 - 75% have 18 carbon atoms, based on 100% and M- is at least one of Cl-, Bur~, NO2-, OH-, and CH3CO2, and a smectite-type clay being hectorite and/or sodium bentonite and wherein the amount of the ammonium compound is from 100 to 120 milliequivalents per 100 grams of the clay, 100% active clay basis.

24. A gellant as claimed in any one of claims 14 to 23 and substantially as hereinbefore described.

25. An oil base drilling fluid comprising a water-in-oil emulsion and a thickening amount of an organophilic clay gellant which is the reaction product of a methyl benzyl dialkyl ammonium compound in which the alkyl groups independently each have from 14 to 20 carbon atoms, and a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay.

26. A drilling fluid as claimed in claim 25 wherein the organophilic clay gellant is a gellant as claimed in any one of claims 14 to 24.

27. A drilling fluid as claimed in either claim 25 or claim 26 and substantially as hereinbefore described.

28. A modification of the method claimed in claim 1 wherein the organophilic clay gellant is the reaction product of a methyl trihydrogenated tallow or a benzyl trihydrogenated tallow ammonium compound and a said smectite-type clay.

29. A method as claimed in claim 28 wherein the smectite-type clay is hectorite.

30. A method as claimed in either claim 28 or claim 29 wherein the amount of the ammonium compound is from 95.5 to 119.9 milliequivalents per 100 grams of clay on a 100% active clay basis.

31. A method as claimed in any one of claims 28 to 30 and substantially as hereinbefore described.

32. A modification of the gellant claimed in claim 14 wherein the ammonium compound is a methyl trihydrogenated tallow or a benzyl trihydrogenated tallow ammonium compound.

33. A gellant as claimed in claim 32 wherein the smectite-type clay is hectorite.

34. A gellant as claimed in either claim 32 or claim 33 wherein the amount of the ammonium compound is from 95.5 to 119.9 milliequivalents per 100 grams of clay on a 100% active clay basis.

35. Methyl trihydrogenated tallow ammonium hectorite.

36. Benzyl trihydrogenated tallow ammonium hectorite.

37. A gellant as claimed in any one of claims 32 to 36 and substantially as hereinbefore described.