US2885298A

US2885298A - Method for manufacturing paint

Info

Publication number: US2885298A
Application number: US525188A
Authority: US
Inventors: Eastman Du Bois
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1955-07-29
Filing date: 1955-07-29
Publication date: 1959-05-05
Anticipated expiration: 1976-05-05

Description

Du Bols-EASTMAN METHOD FOR MANUFACTURING PAINT Filed July 29, 195s MalyV s, 1959 2,885,298 v METHOD FOR MANUFACTURING PAINT Du Bois Eastman, Whittier, Calif., assignor to The Texas Company, New York, N.Y., a corporation of Delaware Application July 29, 1955, Serial No. 525,188 7 Claims. (Cl. 10G-309) in the liquid paint vehicle. Operations such as this also l have the drawback that they are inherently of the batch type rather than continuous.

In accordance with the present invention therejis provided a lnovel method for manufacturing paint by first mixing relatively coarse particles of the solid paint constituents with a vaporizable liquid in such proportions as to form a uid mixture. This mixture is then passed in a stream to a vaporization zone wherein the flowing mixture is heated and liquid vaporized therefrom to form a flowing dispersion of solid particles suspended in vapor. The size of the solid particles is then greatly reduced by subjecting the owing dispersion to turbulence and high velocity, such that the particles impinge against one another and fracture. The disintegrated particles of reduced size are then combined with liquid paint vehicle and other desired paint ingredients to form a finished paint.

In a preferred embodiment of the invention the vaporizable liquid itself is wholly or partly a paint vehicle. In the latter case at least enough paint vehicle is present to remain with and wet the 'ground particles to make them v readily dispersible in subsequently added paint vehicle.

Two main types of operation are possible with the present invention-batch `and continuous. The continuous operation employs charge makeup, and can be either of the single pass type wherein the solid particles pass only f once through the grinding system and are continuously withdrawn; or of the multiple pass type wherein any'oversized particles pass morethan once through the grinding system to assure adequate grinding and fairly'uniform particles while those particles which have reached-the de- 'C sired iineness are continuously withdrawn.

In` the batch type ofoperation there is no charge makeup, and either single or multiple passes may be employed.

The principles of the invention will be described in detail below with reference tothe drawings, wherein:

Fig. l is a schematic ow diagram of an arrangement of apparatusfor manufacturing paint, wherein there is ernployed a fluid energy grinding device comprising opposed nozzles; and

2,885,298 Patented May 5, 1959 2 tion whereinthe liquid content of the uid mixture being 'ground is all paint vehicle which remains with the solids throughout the process.

SINGLE PASS OPERATION Referring to Fig. 1, a fluid mixture or slurry is made up in a mixer 11 by introducing therein a pool of liquid paint vehicle such as mineral spirits, and adding thereto relatively coarse 'particles of the solid paint ingredients such as titanium dioxide, calcium sulphate, and calcium carbonate. Illustrative lists of suitable vehicles and suitable pigments, inert llers and extenders will be included hereinafter.

'I'he proportion of paint vehicle normally should not be less than about 35% of the mixture by Weight and more often 50% is employed. Makeup ingredients are added to the mixer 11 as finished paint is withdrawn from the system, makeup being either continuous or intermittent, as long as the same proportions of ingredients are continuously maintained in the mixer. i The slurry is then pumped from mixer 11 through a line 13 into a vaporizer tube 15 arranged as a coil in a gas fired furnace 17. Other configurations may be ernployed, such as straight pipe lengths joined by return bends; and two or more sections may be placed in different furnaces. The paint vehicle is completely vaporized in the coil 15 and a owing dispersion is formed of solid particles in the vapors of mineral spirits.

This dispersion flows to a pair of opposed axially aligned

nozzles

19 and 21 in a grinding chamber 23 whereby a pair of axially aligned opposed jets of dispersion are discharged at high velocity against one another with great turbulence. let velocity should be greater than 25 feet per second, and preferably more than 100 feet per second, often being several thousand. The relatively coarse particles of solids thus impinge against one another and disintegrate to extremely fine particles of powder.

n The dispersion then flows through a conduit 25 to a water cooled condenser 27 wherein the vapors are condensed and a slurry is reformed containing extremely line particles of solids dispersed in the liquid vehicle. This reformed slurry then passes through a conduit 29 to a 3- way valve 31 and thence through a conduit 33 (including a 3-way valve 34) to thebottom of receiving tank 35.

v In tank 35 the slurry is mixed intimately with other paint ingredients supplied through conduit 41, such as linseed oil, driers, synthetic resins, or any other ingredients which are considered necessary for a particular paint.

Stirring is accomplished by a motor driven stirrer 37, and the lfinished paint passes over the top of bafe 36 and is withdrawn as` needed through a vconduit 39 at the bottom ofthe tank.

' A second alternate receiving tank 35 also is provided, and selective flow to one tank or the other is controlled by the 3-way valve 34.

i The procedure described above also applies to batch operation with a single pass, in which caseno makeup ingredients are added to tank 11 after the initial slurry is formed. Line 38 then serves for emptying tank 35.

The operations described in theV two preceding paragraphs are advantageous when the slurry contains more vehicle ,thanisneeded in the final product, because ex- 1 Fig. 2 is a schematicow diagram showing only va part ofzpaint manufacturing apparatus employing a .modified .grinding device comprising a nozzle of the convergent-diyergent type. v 1 ,;Eor.simplicity,the principles of the. inventionv will be described first as applied to singlepass .continuous operacess vehicle can then be decanted off the top of the receiving

rtank outlets

40 and 40 before completing the paint mixture. Excess vehicle also'can be removed by distillation. Example l i A white oleoresinous gloss paint is prepared by continuously maintaining in the mixer 11 a slurry having the proportions *of 150 `'pounds `of titanium dioxide, 350

1...; pounds of calcium sulphate and pounds. of calcium carbonate suspended in 52 gallons of mineral spirits. The solid ingredients have a particle size of about 30-50 microns.

The slurry is then pumped at a pressure of 425 p.s.i.g. and a rate of l000#/hr. to a coil 15 of 1/2 inch pipe 400 feet long wherein the slurry is heated to a top temperature of 500 F. to vaporize the mineral spirits completely and form a dispersion of solid particles in the resulting vapor. This dispersion is then passed to a pair of

opposed nozzles

19 and 21 of 5/32 inch inside diameter to form high velocity turbulent streams of dispersion which impinge against one another at an angle of 180 to disintegrate the solid paint ingredients.

Thereafter the dispersion passes to condenser 27 wherein the slurry is reformed, and thence flows by way of conduits 29 and 33 into the tank 35. The solid particles in the reformed slurry will have a size of from less than 1.0 to about 6.0 microns.

In tank 35 the slurry is combined with other paint ingredients, as follows:

25 gallons of heat bodied linseed oil (Z4 viscosity,

Gardner-Holdt) 37.6 gallons of ester gum solution (60% non volatile by weight dissolved in mineral spirits) 2 pounds of cobalt naphthenate (6% cobalt) pounds of lead naphthenate (24% lead) After thorough compounding with mixer 37, the 1inished paint is withdrawn through line 39.

MULTIPLE PASS BATCH OPERATION In another type of operation which can be performed with the disclosed apparatus a single batch of mixture to be ground is made up in mixer 11, and this is passed repeatedly through the grinding system until the desired particle size has been obtained. This is accomplished by proceeding as described above for single pass operation, but instead of passing the condensed reformed slurry to the mixing tank 35 the 3-way valve 31 is turned so tlhat the slurry passes through a conduit 51 back to the mixer 11, and thence is recycled through the system again. Condenser 65 normally is uncooled and does not function in this operation, although if desired it may be operated to supplement the action of condenser 27.

Example Il A white outside house paint is prepared by first preparing in the mixer 11 a batch of slurry containing 127 pounds of free-chalking anatase titanium dioxide, 424 pounds of leaded zinc oxide, 297 pounds of magnesium silicate and 120 gallons of mineral spirits. The solid ingredients have a particle size such that 100% passes thru a 100 mesh screen (U.S. standard), 70% passes thru a 200 mesh screen, and 20% passes ythru a 325 mesh screen.

Grinding of the solid materials proceeds exactly as described in connection with Example I, except that the reformed slurry passes through conduit 51 and back to tbe mixer 11. Operation is continued for 1 hour, after Which the average particle size of the solid ingredients is reduced sufliciently that 100% will pass through a 325 mesh screen, and the particles average about 3 microns in diameter.

At the end of 1 hour the valve 31 is turned and the reformed slurry then passes through conduit 33 into tank 35. After settling, 100 gallons of mineral spirits are decanted olf through outlet 40. The finished paint is then formed in tank 35 by adding:

41 gallons of alkali reined linseed oil 13.5 gallons of bodied linseed oil 12.2 pounds of lead naphthenate 1.6 pounds of manganese naphthenate After thorough mixing the finished paint is Withdrawn through line 38.

MULTIPLE PASS CONTINUOUS OPERATION In a third type of procedure with the described apparatus, multiple pass continuous operation is employed. As previously described, a mixture made up in the mixer 11 is passed through the coil 15 and grinder 23 as a dispersion of solid particles in vapor. Instead of condensing this dispersion, however, the condenser 27 is uncooled so that the hot dispersion passes through conduit 29 to a 3-way valve 53 which is turned so that the dispersion then flows to a short conduit 55 leading to a cyclone type of centrifugal separator 57.

Separator 57 is so designed and operated that the major portion of the vapor together with the solid particles which are still too coarse for paint compounding (generally a major portion of the total solids in the dispersion), leave the bottom through a conduit 59 and tihen pass through a 3-way valve 61 and a conduit 63 to conduit 29 as a dispersion of solid particles in vapor. This dispersion then passes through a 3-way valve 31 to condenser 65 wherein the slurry is reformed and passes through conduit 51 back to mixer 11. Regulation of the proportions leaving the top and bottom of the separator is accomplished by a throttle valve 58.

The dispersion leaving the top of separator 57 comprises a minor portion of the vapor together with the small percentage of solids which are line enough to be ready for paint compounding. This dispersion passes to a condenser 71 in which the vapor is condensed to form a thin slurry which passes through a conduit 73 to the conduit 33, and thence into the tank 35 for mixing With other paint ingredients which are continuously supplied in the proper proportions.

Additional solid paint ingredients and liquid paint vehicle in the proper proportions are supplied to mixer 11 to compensate for the portions of solids and liquids removed through the top of cyclone 57. Such additions may be continuous or intermittent as long as the proportions are maintained constant in mixer 11.

Example III In the mixer 11 there is made up a slurry containing paint ingredients in weight proportions of:

24.5 parts of titanium dioxide 64 parts of lithopone 9.75 parts of magnesium silicate 52 parts of Water The solids have a particle size varying from about 420 microns for the magnesium silicate, to about 15 microns for the titanium dioxide.

Slurry is pumped at a rate of 1460 pounds per hour and a pressure of 900 pounds per square inch to a heater coil 15 of l/a inch pipe 600 feet long wherein it is heated to a temperature of 700 F. The resulting dispersion of solids in steam is passed through a convergent-divergent nozzle 75 having a throat diameter of 1A inch wherein the velocity and turbulence are greatly increased to reduce the size of the solid particles by impact with one another. This dispersion then passes to separator 57 wherein 10% of the solids and 15% of the vapor by weight are allowed to pass oli the top and into a Water cooled condenser 71. A slurry is formed having proportions of 24.5 parts of titanium dioxide, 64 parts of lithopone, 9.75 parts of magnesium silicate, and 78 parts of water by Weight, which is passed from condenser 71 into tank 35. The solid particles thus added will haye a iineness of from 0.5 to about 4.5 microns.

When tank 35 is full, value 34 is turned to Imake tank 35 the receiving tank. After a short settling period in

tank

35, 51 parts of Water are decanted 0E through outlet 40. Then enough synthetic latex alkyd resin is added to provide 19.75 parts of resin in the finished paint and the whole mlxture is agitated thoroughly before being withdrawn through outlet 38.

Enough paint ingredients are added to mixer 11 either continuously or intermittently, to maintain constant the proportions of the mixture entering pipe coil 15.

Still another Way for performing the invention is to prepare the solid constituents of an oil base paint by grinding coarse particles in a mixture containing water as the primary liquid ingredient together with a small quantity of an oily vaporizable liquid paint vehicle, just sufficient to coat the ground particles and render them more easily combinable with the rest of the paint ingredients.

Example IV There is made up in the mixer 11 a slurry containing:

625 pounds of titanium-calcium pigment (30% TiOz- 70% CaSO4) 100 pounds of calcium carbonate 25 pounds of magnesium silicate 90 gallons of water 2 gallons of pine oil The solid particles have a particle size such that 100% passes thru a 40 mesh screen, 50% passes a 100 mesh screen and only 5% passes a 200 mesh screen. This slurry is pumped into the coil 15 at a pressure of 375 pounds per square inch and a rate of S25 pounds per hour, and heated to a temperature of 500 F. so as to form a dispersion of the solid particles in vapors of the water and pine oil. Upon passing the dispersion through grinder 23 the solid particles are greatly reduced in size such that they are within the range of 0.4 to 10.6 microns. Then the dispersion passes through condenser 27 wherein its temperature is reduced to 325 F. so as to condense the pine oil while maintaining the water in a vaporous condition.

The dispersion then passes through valve 53 into cyclone separator 57 wherein the steam separates from the solids and ows through a duct 55 into conduit 29 and thence through condenser 65 back to mixer 11 as a liquid.

Ground solid particles uniformly coated with pine oil leave the bottom of separator 57 and pass by Way of

conduits

59 and 33 into the paint tank 35 where they are intimately mixed with:

25 gallons of heat bodied linseed oil solution (70% solids content in mineral spirits) 4 gallons of ester gum solution (60% gum by Weight in mineral spirits) 21 gallons of mineral spirits 20 gallons of heavy mineral spirits l pound of cobalt naphthenate 2 pounds of lead naphthenate Upon thorough mixing the resulting oleoresinous at paint is withdrawn through conduit 38.

Some paint vehicles such as linseed oil, tung oil, soy bean oil, and corn oil tend to decompose when heated to a high temperature, thus having no actual boiling points. With such oils it is still possible to treat the solid paint ingredients so as to render them more easily dispersible by associating small quantities of such oils with water or other vaporizable liquid to form a slurry which is then passed through the 'grinding system as a dispersion of particles of solids and oil in vapor, to disintegrate the solid particles While maintaining the temperature below the decomposition temperature of the oil.

Example V A yslurry is made up in mixer 11 containing:

96 pounds of free-chalking anatase titanium dioxide, 96 pounds of semi-chalking anatase titanium dioxide, 276 pounds of acicular zinc oxide,

215 pounds of magnesium silicate,

2 gallons of raw linseed oil,

85 gallons of water.

The slurry is passed through heater coil 15 wherein it is heated to a temperature of 375 F. to form a dis- 6 persion containing water vapor, linseed oil droplets, and solid particles. After passing through the grinder 23 the dispersion passes by conduit 25, uncooled condenser 27, conduit 29 land conduit 55 to cyclone separator 57 wherein the steam passes off the top Aand the solid particles having a thin linseed oil coating pass off the bottom and are delivered to tank 35.

In tank 35, the solid ingredients are mixed intimately with:

41 gallons of alkali refined linseed oil 14 gallons of bodied linseed oil 12.8 pounds of lead naphthenate 1.65 pounds of manganese n'aphthenate 20 gallons of miner-al spirits The principles of the invention have 'been described above as yapplied to specific paint vehicles and solid ingredients, to illustrate the principles of the invention. However, it is to be understood that these principles also may Ibe employed with many paint ingredients, some of which will be listed below:

PAINT VEHICLES Linseed oil Soy bean oil Benzine Menhaden iish oil Turpentine Corn oil Kerosine Pine oil Benzol Creosote oil Toluol Mineral spirits Tung oil PIGMENTS Aluminum Yellow iron oxides White lead Cadmium yellow Zinc oxide Burnt Sienna Lithopone Burnt umber Titanium dioxide Burnt ochre Litharge Ultramarine Red lead Cobalt blue Venetian red Prussian blue Hematite Chromium oxide Yellow ochre Graphite Chrome yellows Charcoal Raw sienna Coal Zinc chromate INERT FILLERS AND EXTENDERS Asbestine Infusorial earth Gypsum Calcium carbonate White mineral primer Calcium sulfate Barytes Clay Barium sulfate K-aolin Barium carbonate Whiting Silica It is evident that changes in the operation can be employed within the 'scope of the invention. For example, where it is desired to form a slurry of solid paint ingredients in linseed oil or other oil which decomposes at a tem perature below its yatmospheric boiling point, vacuum operation may be employed 'by providing steam 'aspirator jets downstream of the grinder 23.

Another modication is performed by omitting the grinder 23 or nozzle 75 and causing the grinding to take place as the dispersion passes in high velocity turbulent flow through the long tube 15.

In still another modification, instead of forming a slurry, there may be formed a paste containing a relatively small quantity of liquid such as 5 to 10%. This paste is then picked up by a separately generated stream of vapor, such as steam which forms a dispersion for the disintegration of particles. In the latter modification the paste may or may not be -heated prior to being picked up by the hot vapor stream.

Obviously, many modilications and Variations of the invention, as hereinbefore set forth, may be made Without departing from the spirit Iand scope thereof, and there` fore. only sach limitations should be imposed are indicat-ed in the appended claims.

I claim:

1. A method for manufacturing paint Comprising mixing relatively coarse particles of solid paint ingredients with a vaporizable liquid having a relatively low boiling temperature and a relatively higher boiling paint oil in proportions to form a Huid mixture; passing said fluid mixture in a stream through a vaporization zone; heating said fluid mixture to a temperature above the boiling temperature of said vaporizable liquid but below the boiling temperature of said paint oil and forming a flowing dispersion of solid particles and paint oil particles suspended in vapor, said paint oil acting to` coat particles of said solid paintl ingredients in said dispersion and render said particles readily wettable by and dispersible in paint vehicle; reducing the size of said solid particles by subjecting said flowing dispersion to turbulence and high velocity; and combining the resulting oil coated particles of reduced size with liquid paint vehicle to form a paint.

2. A method in accordance with claim l, wherein said vaporizable liquid is water.

3. A method in accordance with claim l, also comprising separating said vapor from said mixture, thereby leaving said particles uniformly coated with said paint oil, and passing said coated particles into paint vehicle to form said paint.

4. A method in accordance with claim 3, also comprising condensing the separated vapor and returning the condensed vapor to make up said uid mixture.

5. A method for manufacturing paint comprising mixing relatively coarse particles of solid paint ingredients with a vaporizable liquid paint vehicle in proportions to form a fluid mixture; passing said mixture in a stream to a vaporization zone; vaporizing said liquid from said mixture and formingv a ilowing dispersion of solid particles suspended in vapor; reducing the size of said particles by subjecting said flowing dispersion to turbulence and high velocity; continuously separating from said dispersion a part of said vapor together with a part of solid particles which have been reduced sulciently in size; recycling the balance of said dispersion through said steps of passing, vaporizing, and reducing size; and condensing the separated part of said vapor to form liquid vehicle associated with the separated part of said solid particles.

6. A method for manufacturing paint comprising mixing relatively coarse particles of solid paint ingredients with a vaporizable liquid paint vehicle in proportions to form a Huid mixture,` more of said vehicle being present than is desired in the nal paint; passing said mixture in a stream to a vaporization zone; vaporizing said liquid from said mixture and forming a owing dispersion of solid particles suspended in vapor; reducing the size of said particles by subjecting said owing dispersion to turbulence and high velocity; removing the excess vehicle over that required for finished paint by condensing said dispersion to reform a fluid mixture, and decanting excess vehicle from the resulting reformed iluid mixture; and collecting said particles of reduced size together with the rest of said vehicle.

7. A method for manufacturing paint comprising mixing relatively coarse particles of solid paint ingredients with water and a relatively high boiling oily vaporizable liquid paint vehicle in proportions to form a iluid mixture; passing said iluid mixture in a stream through a vaporization zone; heating said fluid mixture, to a ternperature above the boiling temperatures of both said water and said paint vehicle and forming a iiowing dispersion of solid particles suspended in steam and paint vehicle vapor; reducing the size of said solid particles by subjecting said owing dispersion to turbulence and high velocity; cooling said dispersion to a temperature between the boiling temperatures of said water and said paint vehicle so as to condense said paint vehicle and coat said solid particles therewith while maintaining said water as steam; separating said steam from the resulting paint vehicle coated solid particles; and combining said coated particles with additional liquid paint vehicle to form a paint.

References Cited in the le of this patent UNITED STATES PATENTS 317,367 Jessup May 5, 1885 2,274,521 Berry Feb. 24, 1942 2,345,191 Gage Mar. 28, 1944 2,460,546 Stephanol Feb. 1, 1949 FOREIGN PATENTS 22,280 Great Britain of 1912 278,765 Great Britain Oct. 12, 1927 314,992 Great Britain Sept. 29, 1930 849,675 France Nov. 29, 1939 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO 2,885,298 May 5,A 1959 D11 Bois Eastman It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 69, for "Value" read mvalve nu.; column 6, in the tabulation, rightnhend column thereof, under the heading "PAINI VRTLIIOT' .Q between HCreosoteoil" in line' 28, and "Mineral spirits" in line 29, insert ma Water Signed and sealed this lst day of September 1959,

Attest:

KAEL AXLTNE ROBERT C. WATsoN Attesting Officer y Commissioner of Patents

Claims

1. A METHOD FOR MANUFACTURING PAINT COMPRISING MIXING RELATIVELY COARSE PARTICLES OF SOLID PAINT INGREDIENTS WITH A VAPORIZABLE LIQUID HAVING A RELATIVELY LOW BOILING TEMPERATURE AND A RELATIVELY HIGHER BOILING PAINT OIL IN PROPORTIONS TO FORM A FLUID MIXTURE; PASSING SAID FLUID MIXTURE IN A STREAM THROUGH A VAPORIZATION ZONE, HEATING SAID FLUID MIXTURE TO A TEMPERTURE ABOVE THE BOILING TEMPERATURE OF SAID VAPORIZABLE LIQUID BUT BELOW THE BOILING TEMPERATURE OF SAID PAINT OIL AND FORMING A FLOWING DISPERSION OF SOLID PARTICLES AND PAINT OIL PARTICLES SUSPENDED IN VAPOR, SAID PAINT OIL ACTING TO COAT PARTICLES OF SAID SOLID PAINT INGREDIENTS IN SAID DISPERSION AND RENDER SAID PARTICLES READILY WETTABLE BY AND DISPERSIBLE IN PAINT VEHICLE; REDUCING THE SIZE OF SAID SOLID PARTICLES BY SUBJECTING SAID FLOWING DISPERSION TO TURBULENCE AND HIGH VELOCITY; AND COMBINING THE RESULTING OIL COATED PARTICLES OF REDUCED SIZE WITH LIQUID PAINT VEHICLE TO FORM A PAINT.