SE450691B - DISPERSIBLE FOR SOLID PARTICLES IN THE WATER AND APPLICATION OF THE DISPERGENT FOR DISPERSING COPPER PARTICLES - Google Patents

Abstract

Compsns. for dispersing hydrophobic particles in water comprise esters (I) prepd. by partial esterification of (a) polymerised fatty acids, polymerised resin acids and/or opt. polymerised fatty or rosin acid derivs. with (b) polyalkylene glycols or their monoesters or monoethers, provided that (I) have a residual acid value above 3. - Specifically component (a) is esp. crude tall oil (CTO) which has been polymerised (e.g. with BF3) and opt. distd. to remove volatiles. Component (a) may also be a residue obtd. by distn. of fatty acids from animal or vegetable fats or oils, or a prod. obtd. by Diels-Alder reaction of conjugated polyunsatd. fatty or rosin acids or by reaction of fatty or rosin acids with polyfunctional alcohols and/or carboxylic acids. Component (b) is pref. a polyethylene glycol (PEG) with a molecular wt. above 600, esp. 4000-10,000. (I) may be used in an amt. of 0.01-5 (pref. 0.3-1) wt.% for dispersing coal particles in water, esp. where the coal has a particle size of 1-200 microns.

Description

450 10 15 20 25 30 35 691 turn depends on the composition of the wood raw material for the sulphate pulp industry. Some crude tall oils have such a composition that they cannot be economically refined via distillation.

The increased proportion of birch and the decreased proportion of pine in recent years mean that pine oil that cannot be distilled has become more common. This crude tall oil is difficult for manufacturers to sell and in some cases it is fired up.

The composition of a distillable crude oil is normally within the following limits: I Acid content: 120 - 170 Fatty acid content: 32 - 55% Resin content: 11 - 50% Unsaponifiable: 5 - 24% A typical Scandinavian crude oil has the following values: Acid content: 143 Resin content: 30% Unsaponifiable: 15% Variations in pine oil depend on the trees used in mass production where they were grown. A pulp cooked on birch only gives about 70% fatty acids and 30% unsaponifiable. Resin acids are only found in loar trees.

Uncharged particles of colloidal size, ie smaller than about 0.1 [mu] m, as well as larger particles, so-called coarsely dispersed particles, have a tendency in solution to agglomerate to form particle aggregates.

This can be prevented according to known principles, for example by steric stabilization or electrostatic stabilization of the particles. In steric stabilization by means of 450 691 polymers, an adsorption of the polymer molecule to the particle surface takes place. It has long been known that the polymers that work best should have a high affinity portion of the dispersant and another portion that is attracted to the particle. It is also known that an addition of substances with ionic groups, such as polyelectrolytes, increases the stability of the dispersion. For larger particles, which settle under the influence of gravity, a stabilization against sedimentation is also required.

Thus, US-A-4 358 293 describes a dispersion of carbon particles in water, in which a nonionic surfactant polyalkylene oxide compound having a hydrophobic moiety and a hydrophilic moiety is used as dispersant, and wherein the hydrophilic moiety comprises at least 100 ethylene oxide units.

From SE patent application 81046h5-0 it is also known to disperse carbon particles in water by means of several different additives, such as a surfactant which adsorbs to the particle surface and causes repulsion between the particles, as well as cooperating hydrophilic polymers which are believed to exert steric hindrance.

SE patent application 8301502-4 finally, describes a dispersant for carbon particles in water obtained by esterification of tall oil pitch with polyalkylene glycol.

Pine fatty acids and pine resin acids can also be reacted with, for example, polyethylene glycol to products with dispersing properties. A partial esterification of crude tall oil with polyethylene glycol or polyethylene glycol derivative during heating provides a dispersant for solid hydrophobic particles in water. This substance has considerably better properties than a pine fatty acid esterified with polyethylene glycol under the same conditions gives in terms of the ability to obtain a particulate dispersion with a high proportion of liquid material which flows liquid. It has now been found that an improved dispersant for solid particles in water is obtained if the viscosity of the crude tall oil is increased, i.e. a molecular enlargement takes place, before the esterification. The dispersant according to the invention thus consists of one with polyalkylene glycol or? a m0 fl0-ester or monoether thereof partially esterified crude oil, which has been polymerized before esterification so that its viscosity at least 50 ° C has doubled, with a residual acid value higher than 3.

An increase in the average molecular weight of crude tall oil has a beneficial effect on its properties as a dispersant after partial esterification with polyethylene glycol. The reason for this is that a reasonably large hydrophobic unit to which different types of hydrophilic groups such as acid and hydroxyl are attached is desirable. To the carboxylic acid groups are added polyethylene glycol chains. The molecule thus formed must have suitable properties in terms of interaction with water to function as a dispersant, ie a nominal water-insoluble part which adheres to the hydrophobic surface and a nominal water-soluble part which has a strong interaction with water. The molecule thus adsorbed on the particle thus provides both a steric protection via the polyethylene glycol chains and an electrostatic one via the groups charged in neutral pH. These two protection mechanisms counteract particle fusion due to the attractive forces (Van de Waals) acting between hydrophobic particles. The size of both the hydrophobic and hydrophilic part is important for how well a dispersant should work. It is known from the literature that the ability of a polyethylene oxide chain to provide steric protection depends on its length. The size and type of hydrophobic unit also affect the adsorption of the dispersant from the aqueous solution to the particle surface.

An increase in the average molecular weight is reflected in an increased viscosity - however, there is no linear relationship. 10 15 20 25 30 450 691 It has been shown that a viscosity of the crude oil at 50 ° C above T 000 mPa-s, measured with an Emila rotary viscometer (Reciprotor A / S, Denmark) gives an improved dispersion ability. A viscosity in the range 7,000 - 8,000 mPa.s seems to be optimal.

It is also essential that the residual acid number in the product obtained is higher than 3, ie that there is a sufficient number of free acid groups left after the reaction, as these contribute to the electrostatic repulsion between the particles to be dispersed. Products with residual acid numbers lower than and around 3 have clearly deteriorated properties compared with corresponding products with higher residual acid numbers. A residual acid number in the range 5 -12 seems appropriate.

Crude oil can be polymerized according to a number of known methods. During heat treatment of crude oil, possibly in the presence of catalysts, reactions take place, which, among other things, lead to an increase in viscosity. Examples of chemical reactions that take place are esterification, ie the reaction of the acid groups with alcohols, both of which are present in the crude pine oil. This reaction is catalyzed by strong acids such as sulfuric acid, of which there are residues in the crude pine oil since the cleavage step. Crude oil has a hydroxyl number of about 25 depending on the free alcohols, and these hydroxyl groups are basically reacted away during the polymerization.

Dields-Alder reactions between molecules with isolated and conjugated double bonds also occur. The amount of conjugated double bonds is crucial for how much product is formed via the Dields-Alder reaction. Conjugation of isolated double bonds is catalyzed by anthraquinone, which is found in the crude tall oil, when the sulphate pulp mills added this chemical to their cooking cells. 10 15 20 25 30 35 450 691 Oxidative polymerization also takes place in crude pine oil. This refers to such reactions between oxygen and olefins, which result in the formation of a high concentration of free radicals. This type of polymerization of crude pine oil is thus facilitated by air supply.

Boron trifluoride is a strong Lewis acid. From the literature, BF3 is a known polymerization reagent for compounds containing double bonds, eg vegetable and animal oils. Also terpenes somcl- and [GLpinen, dipentin, squalene can be polymerized with BF3. Reaction between fatty and resin acids and BF3 is known from the literature. Reactions with alcohols can also occur with the help of BF3.

The viscosity of crude tall oil can also be increased by adding polyhydric alcohol and acid during heating.

Polyvalent acids that may be considered are mainly maleic anhydride, phthalic anhydride, isophthalic anhydride, trimellitic acid.

Polyhydric alcohols that may be considered are mainly ethylene glycol, diethylene glycol, glycerol, trimethylolpropane, ditrimethylolpropane, monopentaerythritol, dipentaerythritol, neopentyl glycol. In addition, substances with both hydroxyl groups and carboxyl groups can be used, such as dimethylolpropionic acid.

A traditional way to increase the molecular weight is stand oil cooking. Treatment with boric acid also polymerizes crude pine oil. Boric acid is known from the literature to give pyrone rings upon reaction with fatty acid.

The dispersant according to the invention is obtained by reaction between polymerized crude tall oil and polyalkylene glycol or a mon ester or monoether thereof. The polyalkylene glycol is essentially composed of ethylene oxide, as it is essential that it has a hydrophilic character. Examples of monoesters thereof are esters formed from carboxylic acids of the type R-COOH, in which R represents a hydrocarbon radical having 1 to 19 carbon atoms, preferably 1 to h of carbon atoms, such as acetic acid, propionic acid, butyric acid. Monoethers of polyalkylene glycol are alkyl ethers, in which the alkyl group may contain 1 to 20 carbon atoms, preferably 1 to 5 carbon atoms. Examples which may be mentioned are monoethers of polyethylene glycol of the formula R-O- (CH 2 CH 2 O) n -CH 2 -CH 2 OH, wherein R represents alkyl having 1 to 5 carbon atoms and n is a number 2 12. However, for economic reasons, polyethylene glycol is preferred. In order for the sterically hindered effect to be pronounced, it is required that the polyalkylene glycol has a sufficiently high molecular weight, at least 600. Preferably, the molecular weight is between 4,000 and 10,000, but even higher values may be possible.

To prepare the dispersant of the invention, tall oil polymer and polyalkylene glycol are reacted with each other in a ratio of 10:90 to 90:10, preferably 30:70 to 70:30, by mixing and heating. A larger amount of tall oil gives a cheaper product, while a larger amount of polyalkylene glycol gives a more efficient product.

If polyethylene glycol is used as the purification component, the reaction is run at 200 to 300 ° C for 1-12 hours at atmospheric pressure, preferably 230-280 ° C, depending on the molecular weight and desired residual acid number.

The dispersant according to the invention can be used for dispersing carbon particles in water, for the preparation of a so-called coal-water slurry. Many ways have been proposed to produce and stabilize coal-water slurries.

The reason for this is that slurries with a high carbon content make it possible to transport and burn coal in liquid form.

In this way, a more risk-free and environmentally friendly handling is achieved than when handling dry, solid coal or oil. To make the coal-water slurry flowable at the concentration areas that come into question, chemicals must be added. Previously used dispersants considerably make the production of a pumpable dispersion of powdered carbon in water considerably more expensive, thereby complicating the use of the new technology. By means of the dispersant according to the invention, a polyalkylene glycol ester of polymerized tall oil with varying amount of ionic groups, such a chemical can be produced at a cheap price, which is of great importance for a commercial use of hydrocarbon water slurries.

When using the dispersant according to the invention for dispersing carbon particles in water, it is suitable that the dispersant is used in an amount of 0.1 - 5%, preferably 0.3 - 1%, calculated on the total weight. The particle size of the carbon is normally in the range 1 - 200 μm.

The invention is described in more detail by the following examples, in which the stated percentage values and quantity ratios are calculated with respect to the weight.

The dispersion properties of prepared reaction products have been determined in the same way as the oil number is determined for pigments (SIS 17 61 05); however, the stated value denotes the amount of carbon particles that can be dispersed into a free-flowing product. The procedure is as follows: 1 g of bituminous carbon with a particle size distribution such that more than 40% is in the range of 60 - 90 μm, weighed into a blasted glass plate. To this is added water with 3% dispersant. The amount of aqueous phase that needs to be added in order to get the carbon slurry free-flowing when processing the carbon powder with a pallet knife.

The accuracy is 0.5%.

Example 1 Heat treatment of crude oil and partial esterification with polyethylene glycol.

Crude oil with the analysis data below (so-called indestructible crude oil) was charged to a reactor with a mechanical stirrer and a protective atmosphere. A short column was connected to the reactor to collect reaction water in the associated publisher.

Analysis data: ST = 134 Resin content = 14% Non-digestible = 23% Viscosity (20 ° C Emila) = 505% Pa.s The temperature of the crude tall oil was raised to 280 ° C and kept there for 2 hours, after which the viscosity was 1,400 mPa.s ( 20 ° C Emila) and the acid number had dropped 32 units to 102.

To this heat-treated crude oil (105 g) is charged polyethylene glycol having a molecular weight of 8,000 (245 g).

The temperature of the mixture was maintained for two hours at 280 ° C.

A 3% aqueous solution of the reaction mixture can disperse a maximum of 68% carbon.

Heat treatment of crude tall oil and partial esterification with polyethylene glycol can also take place in one step. However, this leads to a slightly worse dispersant, a maximum of 67% carbon in the slurry. 10 15 20 25 30 35 450 691 10 Example 2 Heat treatment of crude tall oil from the sulphite method and partial esterification with polyethylene glycol. Even in the production of pulp according to the sulphite method, the extractives of the trees can be extracted. The so-called neutral sulphite anthraquinone process is reported in the literature to give a tall oil of good quality. Through ultrafiltration and evaporation, a stream rich in extractives (dry matter content 40%) can be obtained from pulp boiling according to the sulphite process. This emulsion of water and extractants from the wood raw material can be made to crack by adding dilute acid and heating. Lipid phase which is separated off then has an acid number of 63. By reacting this with polyethylene glycol (molecular weight 8,000) at 280 ° C until the acid number is 8, a substance is obtained which, when water is added (1% of the total mixture) 69 % carbon can be dispersed and the slurry can be poured.

Example 3 Heat treatment of crude tall oil in the presence of BF3 and partial esterification with polyethylene glycol.

Dewatered crude tall oil (1,660 g) with 140 in acid number, 29% resin content and a viscosity of 115 mPa.s (50 ° C) is charged to a reactor with a mechanical stirrer with a protective atmosphere.

The temperature of the crude pine oil is raised to 125 ° C and BF3 solution (20 g) is added. The mixture is kept at this temperature for four hours, after which the temperature is raised to 250 ° C and the reaction mixture is blown with steam for one hour. With water vapor, 120 ml of oil disappears.

The reaction product thus obtained has an acid number of 120 and a viscosity at 50 ° C of 2,100 mPa.s. The boron trifluoride solution maintains a content of 47% in diethyl ether.

TO 15 20 25 30 35 450 691 11 The reaction can also be stopped with the addition of water without steam blowing. Under these conditions, however, the reaction mixture will contain residues of BF. In this way, fatty and resin acids can also be treated.

The table below shows the properties of different dispersants in terms of their ability to make a coal water slurry with a high content of carbon. All dispersants have been prepared by partial esterification with polyethylene glycol (molecular weight 4,000) at 280 ° C.

Lipid moiety Maximum amount of carbon in the hydrocarbon slurry (%) BF3 ~ treated fatty acid 66 BF3- "resin acid 68 BF3-" crude oil '67 Crude oil 06 For comparison, distilled water can disperse about 50% carbon in liquid slurry. Addition of crude pine oil to the water 1% (pH = 7) has no positive effect on this. The effect of the chain length on the polyethylene glycol chain is also important for how the dispersant works. Polymerized resin acid has the ability to disperse a maximum of 68% when reacted with polyethylene glycol having a molecular weight of 4,000, while if the polyethylene glycol chain is extended (molecular weight 8,000) it can disperse 70% carbon in water.

Pure resin acid esterified with polyethylene glycol can disperse 69% carbon and pure pine fatty acid esterified with polyethylene glycol (molecular weight 8,000) can disperse at most 61% carbon in water.

Pure fatty acid and polymerized fatty acid esterified with polyethylene glycol both give carbon / water slurries with short consistency, all other dispersing agents give slurry with 450 691 10 15 20 25 30 12 smoother consistency.

JLXf-.fmßsll Treatment of crude tall oil with polyhydric alcohol and acid and partial esterification with polyethylene glycol. f; By adding polyhydric alcohol and acid to crude pine oil, the viscosity is increased. Tall oil with analysis data according to example 1 (548 g) is charged in a reactor equipped as in example 1 together with Polyol PX (a product consisting of polyhydric alcohols with a functionality between 2 and 4, manufactured by Perstorp AB) ( 91 g) and maleic anhydride. The mixture is kept at 230 ° C until the acid number has dropped to 34, the viscosity is then 5,000 mPa.s (Emila 50 ° C). To 105 g of the reaction mixture is added 2.5 g of polyethylene glycol (molecular weight 8,000) and the temperature is raised to 280 ° C. After 2 hours, the acid number of the mixture is 9 and a 3% aqueous solution can disperse 70% of carbon. Addition of amine to the dispersant also increases the amount of carbon in the hydrocarbon slurry. By adding 0.5% diethylenetriamine to the dispersant prepared as above and allowing the mixture to stand for 1.5 hours at 160 ° C, the hydrocarbon slurry can disperse an additional 1%.

In the same way, other polyvalent acids and alcohols can also be reacted with tall oil. Below are some examples.

It is consistent that in all cases a polymerization has taken place and that the product after reaction at 280 ° C with polyethylene glycol (molecular weight 8,000) has a residual acid number. q) n 10 15 20 450 691 13 Additive chemical in Viscosity of Residual acid number Maximum amount of crude tall oil polymerized in polyethylene carbon in freeflower tall oil long glycol-bonding carbon / H O- (50 ° C), mPa.s ester slurry with 1% dispersant Trimetylo1propane } Trimellitic acid 1 200 6 71 Monopentaerythritol} Maleic anhydride 4 700 7 69 Trimethylolpropane Maleic anhydride 1 600 7 70 Dipentaerythritol Maleic anhydride 40,000 6 71 Boiling oil cooking oil is a traditional way of increasing the molecular weight. 20 ° C, Höppler) is 300 - 500 mPa.s has a viscosity of 3,500 - 6,500 mPa.s (20 ° C) after cooking oil. The viscosity of the above-prepared reaction product between crude oil, trimethylolpropane and maleic anhydride can be increased in 2 hours from 1,600 mPa.s to 14,500 mPa.s (50 ° C) by boiling stand oil at 272 ° C under a protective atmosphere. By blowing the sample air, the same viscosity increase can also be achieved but at a lower temperature, about 250 ° C.

Claims (4)

450 691 14 PATENT REQUIREMENTS A dispersant for solid hydrophobic particles in water is characterized in that it consists of a polyalkylene glycol consisting essentially of ethylene oxide units and having a molecular weight above 600 or a monoester or monoether thereof partially esterified crude tall oil, polymerized before the esterification so that its viscosity at least doubled, with a residual acid number higher than 3. A dispersant according to claim 1, characterized in that the polyalkylene glycol has a molecular weight of 4000-10000. Dispersant according to Claim 1 or 2, characterized in that the crude tall oil was polymerized before the esterification to a viscosity at 50 ° C above 1000 mPa.s, suitably 7000 - 8000 mPa-s. Use of a dispersant consisting of a polyalkylene glycol consisting essentially of ethylene oxide units and having a molecular weight exceeding 600 or a monoester or monoether thereof partially esterified crude tall oil, polymerized before esterification so that its viscosity at 50 ° C is at least doubled by residual acid number higher than 3, for dispersing carbon particles with a particle size in the range 1-200 μm in water, the dispersant being used in an amount of 0.1 - 5%, preferably 0.3 - 1%, calculated on the total weight of the dispersion . we