XANTHAN GUM SLURRIES

Abstract: High concentration polymer slurries contain up to 60 weight % to 75 weight % xanthan gum in a solvent base treated with suspending agents, dispersants, and thinning agents. Mineral oil, diesel oil, kerosene, alcohols (six to twelve carbons), vegetable oil, ester-alcohols, polyol ethers, and the like may be used as the solvent. The preferred suspending agent is either an organophilic clay or hydroxy­ propyl cellulose. The preferred dispersant is either an ethoxylated linear alcohol or a fatty acid ester of vegetable oil or aminal oil. The preferred thinning agent is lecithin. These slurries greatly improve the dispersibiiity of xanthan gum or any other hydrophilic colloid, such as guar, hydroxy­ propyl guar, cellulosics, polyacrylamides, and the like.

Description: HIGH CONCENTRATION POLYMER SLURRIES US. Patent 5,894,880 disclose the method of thickening alcohol/water solvent systems with xanthan gum. This system is then used to suspend a slurry of alginates. U.S. Patent 5,894,879 discloses tie method of thickening alcohol/ water solvent systems with hydroxypropyl celluloso, Other art Includes mechanical and chemical means of improvbig the dispersibility of xanthan gum and other hydro philic colloids. Mechanical mixers are not completely effective. Chemical means consist of either treating the colloid with materials such as dialdehydes that delay hydration or slurring the polymer. The slurries of prior art have two major dis advantages. First, to remain pourable these slurries are limited to polymer concentrations well bclow 50%. Secondly, volatile. solvents in these slurry formulations evaporate when exposed to the atmosphere leaving a crusty film of dried polymer on these surface of the slurry. This crust resists reconstitution into the slurry and is noi dispersible in water. In accordance with the present inyention a high concentration polymer slurry comprises 20-75 weight % of fine mesh xanthan gum; 20-75 weight % hydrophobic solvent base; 0.050.25 weight c% suspending agent; optionally 0.5-1 weight % thinning agent and optionally 0.1-7.0 weight , dispersant. Dy incorporating a thinning agent such as lecithin, pourable slurries at polymer concentrations exceeding 50% can be obtained. The solvent base used in accordance with the present invention is considerably less volatile than that of the prior art and crust formation can be substantially avoided. The polymer to be dispersed is preferably xanthan gum. Other similar hydrophilic colloids can be used in these formu- lations, such as guar gum, hydroxypropyl guar, cellulosics and polyacrylamides. The total weight of polymer in the final composition is from 20-75 weight 50. A finely divided form of polymer is preferable (200-mesh, Tyler screen or finer) to achieve these levels. The sieve opening is 0.074 mm in this 200-mesh screen. The term "hydrophobic solvents" herein means anhydrous solvents, i.e. those containing less than 0.1% water, that are insoluble in water and do not solvate or swell hydrophilic colloids and thai have a melting point cf no more than 500C and a vapor pressure at 20tC of no more than 1 torr. The solvent base can be one or more of the following: mineral oil, diesel oil, kerosene, C6-12 alcohols, vegetable oil, ester-alcohols e.g. 2,2,4-trimethyl-pentanediol-1, 3-monoisobutyrate (sold under the trade mark Texanol by Eastman Kodak), polyol ethers, e.g. ethylene glycol, polyethylene glycol, propylene glycol, and ethylene glycol monobutyl ether, silicone oils and halogenated solvents. The amount of solvent used is 20-75 weight %. One preferred solvent base is a mixture of diesel oil or kerosene in about equal amounts with a mixture of a C6-10 alcohol. Another preferred solvent is mineral oil. The resi of the slurry is made up of minor amounts of suspensing agents, dispersants, and thinning agents. The preferred suspending agent, the amount of which is preferably 0.05-0.25 weight C; 35 an organophilie clay or hydroxypropyl cellulose. Hydroxypropyl methylcellulose, hydroxybutyl methyl cellulose, aluminum/phosphate soaps, aluminum stearate/fatty acid soaps, dehydrated castor oil, fine-mesh fumed silica, quaternary salts of sodium cellulose (SoloidR), and similar viscosiflers or thixotropie agents for the beforementioned solvents can also be used. The preferred dispersants, which are critical only to the most hydrophobic solvent systems, are ethoxylated linear alcohols. Fatty acid esters of vegetable or animal oils, ethoxglated nonyl phenols, and similar surfactants are also acceptable for dispersion of very hydrophobic solvents of the invention. Ethylene glycol monobutyl ether and other glycol ethers are used as dispersants in less hydrophobic solvent systems. When it is present, the amount of dispersant is 0.1-7.0 weight /0. The preferred thinning agent, when used, is lecithin. Lignosulfonate salts, salts of naphthalene formaldehyde condensate and naphthalene sulfonic acid condensate also can be used. The amount of thinning agent is 0.5-1 weight %', pre ferably 0.85-0.9 weight %. The percentages of the above components should add up to lOOC,j, so obviously sclection of exact amounts from within these ranges can be made by those practising this invention. The procedure to make the slurries is generally simple: The solvent base is put in a suitable container and agitated. The selected dispersing/suspending agents are added, and the polymer is then slowly added with agitation until a uniform slurry is obtained. Eductors attached to suitable containers equipped with circulating pumrs can also acceptably mix the slurries. The high-concentration polymer slurries of tliis Invention can be used in any application requiring aqueous polymers. They are particularly applicable in conditions of minimal mixing agitation given to the aqueous fluids to be viscosified. Dosages or formulation of the slurry are dependent upon the end use of the slurry or polymer. fligh-concentration polymer slurries are particularly useful in oil field appli- cations. When the high-concentration polymer slurry is used, it is mixed into the water to be viscosified under agitation, in a volume sufficient to deliver the desired weight of the polymer, until the polymer is fully hydrated. This invention is further illustrated by the following examples. EXAMPLE 1 Mixing Procedure for High Concentration Polymer Slurry 1. Place solvent in a suitable container. 2. Agitate solvent with sufficient shear to allow for incorporation of polymer in Step 4. 3. Add dispersing agents/suspending agents, as required. 4. Add polymer slowly. Mix until slurry is uniform. Typical Slurry Formulations Ingredient weight e Formulation A Octyl alcohol 24.60 Methanol 2.50 Hydroxypropyl cellulose 0.25 EGMBE (Ethyleneglycol monobutyl ether) 0.30 Diesel No. 1 21.50 Lecithin 0.86 Fine mesh xanthan gum 50.00 Ingredient weight % Formulation B Texanol (ester alcohol Eastman Kodak) 46.57 Methanol 2.50 Hydroxypropyl cellulose 0.06 Lecithin 0.87 Fine mesh xanthan gum 50.00 Formulation C Texancl 49913 Lecithin 0.87 Fine mesh xanthan gum 40.00 Formulation D Diesel No. 1 or No. 2 47.93 Organophilic clay 1.00 Lecithin 0.87 EGMBE (Ethyleneglycol monobutyl. ether) 0.30 Fine mesn xanthan gum 50.00 Formulation , per 100 gal. slurry Mineral cil 80 gal. Organophilic clay 8.5 lb. Ethoxylated linear alcohol 2 gal. Fine mesh xanthan gum 290 lb. Ingredients per 100 gal. slurry Formulation F Dodecyl (lauryl) alcohol 32 gal. Methanol 3 gal. Ethylene glycol monobutyl ether 8 gal. Hydroxypropyl cellulose 2.5 lbs. Kerosene 30 gal. Lecithin 10 ib. Fine-mesh xanthan gum 485 lbs.

Claims: 1. A high concentration polymer slurry comprising 20-75 weight % of xanthan gum; 20-75 weight % hydrophobic solvent base; 0.05-0.25 weight % suspending agent; optionally 0.5-1 weight % thinning agent and optionally 0.1-7.0 weight % dispersant. 2. A slurry as clalmed in Claim 1 in which the xanthan gum is of 200 kesh or iirer, Tyler screen. 3. A slurry as olaimed in Claim 1 or 2 in which the solvent base is one or more of mineral oil, diesel oil, kerosene, C6-10 alcohols, vegeiable oil, ester-alcohols and polyol ethers. @, A slurry as claimed in Claim 1, 2 or 3 in which the suspending agent is organophilic clay or hydroxypropyl cellulose. 5. A slurry as claimed in any preceding claim in which lecithin is included as the thinning agent. A slurry as claimed in any preceding claim in which ethoxylated linear alcohols or fatty acid esters or vegetable or animal oils are included as the disperspersant.

Inventors: CARICO, ROBERT D, LINDROTH, THOMAS A, PICKENS, PATRICK A
Applicants: MERCK & CO. INC.
Application year: 1980
Main classification: C08L5
IPC codes: C09K8, C08J3, C08L5, F02B3, C08L21, C08L7, C08B37