US2487000A - Process of separating the constituents of tall oil and similar mixtures - Google Patents

Description

Nov. 1, 1949 s. E. TAYLOR EI'AL PROCESS OF SEPARATING THE CONSTITUENI'S 0F TALL OIL AND SIMILAR MIXTURES Filed Dec. 3, 1945 3 Sheets-Sheet 1 an m 0/1, Jill? I 3 "Emu #44 014 mu 8 5105965 mm 2 p/ra 3 [4 m MIL m4 caou'o canons/:6: a: 5 rm um. 0

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JUAN/rm GEORGE E. TAYLOR JOE s METGALF LEWIS L. BRANscova Nov. 1, 1949 e. E. TAYLOR EIAL 2,487,000

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o o o o n n a 2 O SPECIFIC ROTATION gwuemtow GEORGE E. TAYLOR JOE SMETOALF LEWIS L.BRANSCOMB cam/71% a Patented Nov. 1, 1949 PROCESS OF SEPARATING THE CONSTITU- ENTS OF TALL OIL AND SMLAB MIX- TUBES George E. Taylor, St. Louis, Mo., and Joe 8. Metcalf and Lewis L. Branscomb, Anniston, Ala, assignors to Monsanto Chemical Company, a

corporation of Delaware Application December 3, 1945, Serial No. 632,540

31 Claims. (01. zoo-47.5)

1 This invention relates to an economical and commercially feasible process for separating and recovering the fatty and resin acids present in tall oil or other mixtures containing both of these materials.

An object of the invention is to provide a process for recovering fatty acids in the form of alkyl esters from mixtures of the above type.

Another object is to provide a process for recovering abietic acid from tall oil and similar mixtures containing same in combination with fatty acids.

An additional object is to provide a process for heat treating abietic acid whereby this material is converted into a stabilized product simulating commercial rosin.

Other objects of to those skilled in folds.

Tall oil is the resinous and fatty byroduct ob ed in the production of paper pul p from resm bearing woods by the soda, sulflte and sulfate processes. It is a dark colored viscous liquid consisting essentially of a mixture of roughly equal proportions of unsaturated fatty acids and resin acids together with a relatively small proportion of unsaponiflable matter, including sterols. Tall oil being a crude semi-natural product varies in composition considerably. Thus the fatty acid content may vary from 36% $1 [154%, the resinlgacgi content from 38% to 58% e unsapo e ma eri hlghas 18%. t al from 6.5% to as Owing to a number tall 01] itself has not been extensively used on the invention will be apparent the art as the description unand of great com-' oil have been proposed. These proposals have involved fractional crystallization, fractional distillation, selective esterifieation, selective splitting of fatty and resin acid soaps, selective splitting of tall 011 glycerides and extraction by means of selective solvents. These and other known methods have achieved varying degrees of success, but they have not been entirely satisfactory since they produce at best only a very rough separationof the components of tall 011 with the result that the fatty acids or their esters are contaminated with resin acids and the latter are invariably contaminated with substantial quantities of fatty acids or fatty acid esters and unsaponifiable materials.

Now we have developed a process by which it is possible to obtain a much more eiiicient and economic separation of resin acids and fatty acids from tall oil and similar mixtures. This process yields fatty acid esters, abietic acid, heat stabilized abietic acid and a viscous resin oil, all of which are obtained in a commercially saleable form.

. until about 85% of tall oil is collected as a distillate. This distillate is then cooled and centrifuged to remove crystalline abietic acid, leaving a mother liquor consisting of tall oil of decreased abietic acid content.

The mother liquor is charged into a suitable reactor where it is reacted with methyl, ethyl. propyl, isopropyl, butyl, isobutyl, amyl or isoamyl alcohol, in the presence of an acid catalyst, to form a mixture of fatty acid esters and abietic acid.

The resulting reaction mixture is washed with water to remove excess acid catalyst and alcohol and then fractionally distilled under reduced pressure, with or without steam, to recover an initial fraction consisting of substantially pure esters, a second fraction comprising abietic acid and a relatively small proportion of fatty acid esters, and a third fraction consisting of a high boiling resinous pitch.

The second fraction is cooled to separate 'out a second portion of abietic acid which is centrifuged to separate esters, free fatty acids, etc., and then washed with hot water or alcohol. The

effect of materially lowering the fusion point of the abietic acid, decreasing its acid and rosin acid number, lowering the iodine number and increasing its content of unsaponiflable matter. It also converts the crystalline abietic acid into a product simulating rosin which has up to 30% by weight of dehydro abietic acid and a color grade of WW to X orbetter.

Instead of recovering the abietic acid in a plu rality of steps, the distilled tall oil may be esterifled directly and the abietic acid separated from the esterified mixture in a single step by cooling and centrifuging. Moreover, the separation of the abietic acid from the ester mixture may be carried out prior to or after the step of fractionally distilling the ester mixture, see for example, Figures 2 and 1 respectively.

For a more complete understanding of the present invention, reference is made to the accompanying drawings.

Figure 1 illustrates one embodiment of the process of the present invention and Figure 2 represents an alternative and preferred embodimentof the invention.

Figure 3 is a graphical representation of the effect of heat treatment on the optical properties of abietic acid. The optical rotation values were determined at a temperature'of about 22 C. by means of a Lippich half-shadow polarimeter using a 20 cm. sample tube containing the heat treated abietic acid and a sodium arc lamp as a source of yellow light, The optical rotation values were converted into specific rotation values in the usual manner and the latter were then used in plotting the graph.

Referring to the drawings by reference characters, crude tall oil which has been dried in any suitable manner is charged into a tall oil still 2 by means of pipe I where it is subjected to steam distillation under an absolute pressure of about 10 mm. to 50 mm. of mercury and at a temperature of from 145 C. to 285 C., the steam used for this purpose being supplied by means of pipe 3. The steamdistillation is carried out until about 85% of the tall .011 is distilled. and the resulting distillate is discharged by pipe 4 into air-cooled condenser 5 where it is condensed. The condensate consisting of refined tall oil is conducted by pipe 6 into tall 011 receiver 1.

The still residue, designated pitch in the flow sheet, is discharged by pipe 8 into storage vessels 9. This product is a black, tacky to brittle solid which is insoluble in water, soluble in xylene,

toluene and benzene and slightly soluble in a1-,

cohol.

The purpose of distilling the tall oil is to improve its odor and color and to remove sulfonic acids and other impurities which tend to hydrolyze the methyl esters which are produced and distilled at a subsequent stage 'of the present process. Distillation is the preferred method of accomplishing these results, but it should be clearly understood that other methods of refining the tall oil are within the scope of the invention.

The distilled tall oil is cooled to room temperature and a substantial amount of crystalline abietic acid separates out. The crystal slurry thus obtained is conveyed by pipe Iii into centrifuge ii in which the crystalline abietic acid is separated from its mother liquor. The abietic acid recovered is washed in the centrifuge with hot water or methanol and is then transported by means of a suitable conveyor 12 to an abietic acid receiver or melting tank II.

The mother liquor consisting of distilled tall oil of decreased abietic acid content and the washings are discharged from centrifuge II and then conducted after drying in any suitable manner to esteriiication tank Ii by means of pipe I.

In the esterincation tank the ftty acids of the distilled tall oil are selectively esterifled by reaction with methanol in the presence of an acid catalyst such as HCl, the reaction taking place at a temperature of from 40 C. to 60 C. and preferably from 40 C. to 45" C. The methanol and 1101 used in this reaction are fed into the esterification tank by means of pipes i6 and il respectively. The amount of methanol employed may vary widely so long as the theoretical requirements are met, but we prefer to use it in an amount equivalent to about 50% by weight of the distilled tall oil treated. HCl in an amount corresponding to about 2% to 5% by weight of the distilled tall oil is preferably used in the reaction, but larger or smaller amounts may be employed if desired. 1

After the esterification reaction is completed, the excess methanol and HCl are separated from the reaction mixture by extraction with water which is introduced into esteriflcation tank ll by means of pipe ll. The extract containing 1101 and methanol flows by pipe it into neutralizing tank 20 where it is neutralized with caustic soda or another suitable alkali. The neutralized extract is then conveyed by pipe IIIA into still 2| where the methanol is distilled and discharged by pipe 2 IA into storage vessel 22 from which it may be returned for reuse in the next batch by means of pipes 23 and it. The brine solution separated as a result of the methanol distillation step is di charged from still 2| by means of pipe IIB.

The washed esterified tall oil mixtureisconveyed by pipe 24 into fractionating column 25 wherein it is subjected to vacuum steam distillation, the steam used for this purpose being introduced by pipe 26., The distillation is carried out at an absolute pressure of from 10 to 50 millimeters of mercury and at a temperature of from 220 C. to 250 C., and an initial fraction consisting essentially of methyl tall oil fatty acid esters is separated, which fraction leaves the fractionating column 25 and passes through a. suitable condenser (not shown) and pipe 21 into a receiver 2|.

In general, the methyl esters thus obtained have the following properties, it being understood that the properties will vary somewhat depending upon the degree to which the fatty acids are esterifled and/or the efliciency of fractionation:

Acid No. 8.8 Rosin acid No 3.0 Unsaponifiables per. cent 6.1 Free fatty acids do 1.8 Abietic acid do.. 1.6

I The e esters are saleable as such and 'are excellent raw materials for use in the production of higher alcohols. dicarboxylic acids, long chain aldehydes and ketones. hydrogenated to produce products which are eminently suitable for use as textile oils.

The separation of the methyl esters by distillation is preferably controlled by obtaining the acid number of the distillate samples. If a product having an average acid number of about 6.6 is desired, the distillation of the methyl esters is discontinued as soon as the distillate samples yield an acid number of from to 12. However, if a product having a lower average acid number is desired, the recovery of methyl esters is discontinued when the acid number of the samples falls below 10. By this method of control, it is possible to obtain methyl esters having an average acid number of from about 2 to about 6.6 or a higher acid number, but as a product having a low acid number is desirable, it is preferred to carry out the distillation in such a manner that the product has an average acid number which does not substantially exceed 6.6.

After the desired methyl ester fraction has been recovered, the distillation is then continued at the same absolute pressure but at a temperature of from 250 C. to 300 C. and an intermediate fraction consisting essentially of abietic acid and a relatively small amount of methyl esters is separated, leaving a residue of pitch which is removed from the column and transported by means of a suitable conveyor 29 to storage vessel 9 where it is combined with the pitch recovered in tall oil still 2.

The intermediate fraction, after being condensed by means of a suitable condenser (not shown), is conveyed by pipe 30 into a methyl ester-abietic acid receiver 3| where it is cooled to a temperature sufficient to obtain substantially complete crystallization of the abietic acid. The resulting crystalline slurry is conducted by pipe 32 into centrifuge 33 where the abietic acid separated from its mother liquor is purified by washing with hot water or methanol. The hot water or methanol employed for this purpose is intro duced by pipe 34 and is discharged from the centrifuge by means of pipe 35..

The washings and the abietic acid mother liquor separated in centrifuge 33 are combined and conveyed by pipe 35 into storage tank 33. The resulting mixture may be recycled to esteriflcation tank l5 by means of pipes 31, 23. and it, where it may be added to distilled tall oil of decreased abietic acid content and reworked in the manner indicated in the fiow sheet.

As an alternative to this procedure, the mixture may be allowed to accumulate in storage tank 35 and then reprocessed separately in the same manner to recover additional quantities of abietic acid and methyl esters. When this is done, a final mother liquor is separated in centrifuge 33 and conveyed by pipe 44 into a heat treatment tank 45. In this tank the mother liquor is heated to about 280 C.-290 C. and treated with steam, the steam being introduced by means of pipe 46. The molten product thus obtained is discharged by pipe 41 into a suitable resin oil receiver 48 where it is allowed: to cool in the presence of carbon dioxide, nitrogen or another suitable inert atmosphere.

The abietic acid separated in centrifuge 33 is removed and transported by any suitable means 38 to the abietic acid receiver or melting tank I3 where it is combined with the abietic acid sepa-. rated in centrifuge I I.

The abietic acid recovered in the above de- They may also be partially Gil scribed manner has substantially the following properties:

Acid No 174.8-1825 Rosin acid N0 17211-1804 Saponiflcation No. 180.9-184] Unsaponifiables per cent 1.3- 1.7 Abietic acids do.. 91.5-96.0 Free fatty acids do 1.0- 1.2 Methyl esters do 3.6- 1.1 Color White to cream colored crystals This product has a tendency to become rancid and odorous due to the presence of fatty acids and its color darkens on ageing. It also differs from commercial rosin in that it has a negative specific rotation and has a marked tendency to crystallize after melting but before any extended heat treatment.

The abietic acid thus obtained may be stabilized as such or in the form of a non-crystalline product simulating commercial rosin.

In order to obtain stabilized abietic acid, the crystalline product is first melted in tank l3, preferably in an inert atmosphere, and then flaked on chilled rolls or extruded, molded. or otherwise shaped into blocks or other suitable forms. These products upon cooling are transformed into solid crystalline masses which, by virtue of their reduced surface, are much more stable to oxidation than the original loose mass of abietic acid crystals.

To produce a stable product simulatin rosin. the crystalline abietic acid is preferably heated to a temperature of from 280 C. to 290 C., and then held at this temperature for 6 hours while a current of steam, introduced by pipe 39, is passed through the molten material. The molten mass is discharged 'by pipe 40 into a stabilized tall oil resin receiver II where it is permitted to cool to room temperature in an atmosphere of carbon dioxide, nitrogen or another suitable inert gaseous medium. The resulting product is a brittle glassy solid which resembles commercial rosin in appearance and chemical properties such as acid, saponification and iodine numbers, softening point, etc.

The distillate including fatty acids, esters, abietic acid and other low boiling impurities passes through a condenser (not shown) wherein the distillate is condensed and then discharged by pipe 42 into distillate receiver 43.

As an alternative to the above method of handling the heat treated abietic acid, .the molten product may be poured between two smooth faced water-cooled rolls, preferably steel rolls, to rapidly chill the melt. The solidified product which is removed from the rolls by means of a suitable scraper, has a clear glassy-like appearance and consists of flakes which may vary from 0.001 to 0.5 of an inch in thickness depending upon the conditions of operation. These flakes are in a very convenient form for handling since they do not stick together during storage and consequently they may be readily removed from the storage container in a dry free flowing condition. Moreover, due to their physical characteristics. they are in a form in which they may be readily dissolved in solvents without the necessit for additional treatment such as grinding.

The rolls used in the above operation are preferably of small diameter, for example, from three to twelve inches, and are rotated toward each other at a speed of from 300 to 1800 R. P. M. The thickness of the flakes may be controlled to a considerable extent by variation of the distance between the rolls and the speed of rotation. The

rolls may be cooled in a variety of ways. but genferallysueh cooling is carried out by circulating water on the interior of the rolls.

Startin with 100pounds ofdrytalloiland following the above process for recovering abietic acid, the following products are obtained in substantially the quantities indicated:

The following examples will serve to illustrate in greater detail the procedure used to heat treat the abietic acid recovered by the above described process:

Example 1 Crystalline abietic acid having the following properties:

Acid No. 182.6 Rosin acid No 160.4 Saponification No. 184.7 Unsaponiflables 1.7 Specifi rotation 12.2

from 280 C.-290 C. in the presence of an atmosphere of carbon dioxide. When up to temperature, steam is bubbled into the molten mass at the rate of 5 grams per minute for a period of 80 minutes or until 400 grams of steam has been added. The steaming is discontinued and the product is then maintained at a temperature of 280 C. to 290 C. under an atmosphere of carbon dioxide for about 3 hours. At the end of this time, the product is cooled in an inert atmosphere to 150 C.170 C. and poured into a paper boat. On setting a product is obtained which has substantially the following properties:

Acid No I 158 Rosin acid No 157 Saponification 162.5 Unsaponifiables per cent 9 Dehydroabietic acid d 23 Specific rotation degrees 41 Softening point do 80 This product is adapted for use in the production of pale varnishes, ester gum, modified synthetic resins, white paper size, soap, medicinal adhesive tape and many other commercial products.

Example II 21.3 lbs. of crystalline abietic acid having the following properties:

Acid No 174.8 Rosin acid No 172.! Saponification No 180.9 Unsaponifiables per cent 1.3 Abietic acid 91.5 Free fatty acids d 1.0 Methyl esters ..do 3.6

-is melted and brought up to a temperature of 8 rosin is obtained, which has substantially the following properties:

Acid No 173.0 Rosin acid No 171.6 Saponification No 175.7 Unsaponiflables per cent" 3.1 Softening point C 66 Color r x A In view of the fact that most manufacturers prefer ester gum and synthetic resins having as high a softening point as possible, the above heat treated abietic acid is particularly suitable for use in the production of these products since it has a high softening point and thisproperty is carried through to the finished resin or gum. This heat treated product is also suitable for use in the production of paper size, pale varnishes,

high grade rosin soaps, molding compositions, paints and lacquers.

Anyone of the various properties of heat treated abietic such as specific rotation, acid number, saponiflcation number, percent unsaponifiables, softening point and disproportionation may be varied over wide limits but not without effect on the others, Therefore, the conditions of heat treatment will depend upon the desired specifications of the product.

Thus by the process of the instant invention heat treated abietic acid having the following range of properties has been obtained:

Acid No 140-175 Saponification No 142-182 Softening point 74.5-87" Color W to X or better Dehydroabietic acid Up to 30% Unsaponifiables. 0.8 to 16% Specific rotation 12.2 to 48.7

As indicated above the abietic acid heat-treatment is preferably carried out at a temperature of from 280 C. to 290 C. but temperatures ranging from 250 C. to 350 C. may be employed if desired. The time of heating varies inversely with the temperature. The higher the temperature the lower is the heating time and vice versa. Thus at 350 C. the heat treatment may be carried out in about hour whereas at 250 C. about 8 hours heat treatment is required to obtain the same results.

The heat treatment may be carried out in a single step or a plurality of steps, that is, the abietic acid may be heated, preferably in an inert atmosphere, to a temperature from 250 C. to 350 C. and then steamed or subjected to reduced pressure to remove volatile impurities or these two operations may be carried simultaneously. The latter procedure is preferred one because it is more economical, easier to control and it provides a means whereby products having predetermined properties may be obtained.

The heat treatment of abietic acid brings about a change in its chemical and physical characteristics. It converts the abietic acid into a glassy brittle solid simulating commercial rosin; it reduces its iodine number to marked degree; it increases its optical rotation from a negative or a low positive value to a high positive value; it reduces its tendency to crystallize from a solution or melt thereof; it decreases its acid and rosin acid numbers; and it increases its content of unsaponiflable matter, although the last mentioned effect may be more than counteracted by properly correlating the steaming operation with the heating step.

9 The above changes in physical and chemical characteristics are apparently due to an intra and inter molecular rearrangement of the hydrogen atoms which takes place without aflectin the carbon skeleton. This is further manifested by the fact that the products are: more resistant to ongen absorption indicating a marked change in the type unsaturation and also by the fact that the saponiflcation number is not substantially changed, thus demonstrating that the carboxyl groups are not appreciably aflected by the heat treatment,'which, therefore, must act upon the hydrocarbon skeleton only.

In order to demonstrate the effect of the heat treatment employed in the process of the instant invention, the following experiments were carried out.

Samples of crystalline abietic acid recovered by the.above process were heat treated as follows:

The weighedsample was melted in a flask under an atmosphere of carbon dioxide and heated to a temperature of about 285 C. at which point steam was bubbled into the liquid. Any material distilling out of the flask with steam condensed hot and termed distillate.

At the end of a specified period of time the steaming was stopped and carbon dioxide blown over the surface of the molten product. Several runs were made in which the heating period extended beyond the steaming.

After completion of the heat treatment, the sample was allowed to cool (under CO2) to 155 C.-170 C. at which time it was weighed. poured into a paper boat and allowed to set.

The distillate was dried and weighed and the steam consumption was measured by loss in weight of the flask used as a steam generator.

was-

. l flable content increases and the acid number of the abietic acid is reduced.

The tendency of heat treated abietic acid to crystallize when cooling is diminished by prolonged heating. This is apparently true regardless of the amount of unsaponlflables present, although dehydro abietic acid tends to make the I product more crystalline.

Although a considerable amount of abietic acid is removed, steaming tends to removethe lower bofling free acids and unsaponiflables. Analyses of various distillates showed the presence of only small amounts of dehydro abietic acid. indicating that the bulk of this material is left in the product.

The rate of steaming is very important in determining the acid value and the softening point of the heat treated abietic acid. Thus the rate can be such that the unsaponiflables will be removed about as fast as they are formed, and the product will have a high acid value and a high softening point. If a lower steam rate' is used. a gradual drop in acid values and softening points occurs throughout the steaming period. If the heating period extends beyond the steaming time,-

the acid values and softening points decrease rapidly due to the formation of unsaponifiables which are not removed.

The total amount of steam used in the above experiments is roughly proportional to the amount of distillate obtained, but actually this factor may vary considerably depending upon the The above experiments are summarized in the temperature and time of heat treatment and also the properties desired in the flnal product.

As indicated by the accompanying graph (see Fig. 3) the specific rotation values of theheat treated abietic acid increase in proportion to the heating period.

following table, it being understood that the total 40 The f re d s sure has been restricted to heating time includes the steaming time. a batch process, but it will be apparent from the Total Steam Percent Bolton- Weight H Weight Weight eating ing Acid Percent deh dro ing Optical smpb Time, Time, stem Product number Unsap. Ab tic Point, Rotation min. min. .4010 0.

454 30 30 400 115.0 a0 05 53s a5 a0 10 411 110.4 2.4 82 501 00 00 121 435 115.2 4.0 as 454 00 00 141 314 115.0 3.0 05 500 so 201 340 100.0 4.0 02 925 120 00 401 001 110.2 5.2 02 500 100 100 444 205 118.0 3.0 as 453 100 100 113.1 3.5 30 see 500 240 so 211 355 15111 0.1 00 accom- 1.000 240 240 003 115 115.0 23 01 panying 1.415 240 240 cm 1.125 112.5 44 a5 graph. 2.090 240 240 12: 1.050 10110 5.2 03 1.100 240 240 005 1.200 113.0 3.1 00 1,100 240 240 050 1.310 112.4 2.1 00

500 045 so 112 301 152.4 11.8 15.5 454 450 a0 102 051 151.0 12.4 15 500 450 00 301 149. 14.5 14.0

constant.

Some decomposition of the abietic acid also occurs as is evidenced by an increase in the unsaponiflable material produced and also by the reduction in acid number.

As the time of heating incrmes, the unsaponifollowing description that the process may be .carried out continuously. I

In describing this embodiment of the invention, reference will be made to Figure 2 which illustrates the flow sheet of our continuous process. Crude tall 011 is continuously pumped from a suitable source into a two stage preheater II which is heated with'steam at 50 pounds per square inch in the first stage and with chlorinated diphenyls at 24 lbs. per square inch in the second stage. The preheater discharges into flash tank 53 by way of pipe I: wherein moisture and volatile matter are removed from the tall oil and ass-moo ll exhausted into the atmosphere through outlet Pipe 04. The flash tank during this operation is maintained under a vacuum and at a temperature of from 120 C. to 280' C. The hot dry tall oil is pumped through pipe I into a suitable iractionating column 00, preferably a bubble cap fractionating column, by means of a pomtive displacement pump (not shown).

Fractionating column I is provided with a reboiler (not shown) which is located near the bottom of the column. The reboiler supplies the latent heat required to vaporize the high boiling constituents; the latter in turn give up their latent heat to vaporize the lower boiling constituents in the incoming feed and the refiux.

superheated steam is charged through pipe II into column 00, the steam being introduced into the bottom of the reboiler in order to accelerate the thermosyphon effect between the reservoir in the bottom of the column and the reboiler.

The'low boiling components, abietic acid and fatty acids, vaporized by the steam pass up through the rectification system of the column and here the high boiling constituents are separated from the vapors and returned to the reboiler section of the column. The tall oil vapors pass by means of pipe 00 into a partial condenser OI which condenses the tall oil vapors and permits the steam vapors to pass on through pipe 02 into an entrainment separator S3 where the steam is separated and discharged from the system by means of pipe 00. The condensates separated in separator 00 and condenser I drain through pipes 00 and I respectively into split fiow box 60', the latter being employed to maintain the composition of the refined tall oil substantially constant. This is accomplished by circulating a fixed portion of the tall oil back to the top of fractionating column I. as refiux by means of pipe 00' and taking the remaining portion as.

product.

The high boiling pitch overflows continuously from the bottom of the column into pitch receiver 00 by means of pipe 01.

The refined tall oil is discharged from the split fiow box into pipe 00 at a predetermined rate where it is combined with recycled methanol, an intermediate ester fraction and 'a solution of hydrogen chloride in methanol, these three materials being introduced into pipe i! by pipes ll, 5

II, and I2 respectively. The resulting mixture is fed into a three stage continuous mixer (not shown) where it is thoroughly mixed and discharged into an esterification tank I! of sufiicient size to allow at least one hour's sojourn The methanol-water-hydrochlorie acid mixture is conducted by pipe 11 into a methanol recovery system which includes a neutralizing tank and a rractionating column. In this system the solution is neutralized with a caustic soda solution or other suitable alkali introduced by pipe 10 and then the resultin solution is charged into a fractionating column where the alcohol is removed, condensed and recycled by pipe II to theesteri- 12 flcation' tank. The remaining salt solution is drawn oif continuously from the bottom oi. the column and discharged from the system by means oi pipe 10.

The hot crude esters are conveyed by pipe 00 into a continuous crystallizer II which may take the form of a water jacketed trough containing a long pitch ribbon conveyor. Simultaneously therewith, a fixed quantity of resin free mother liquor is pumped through pipe 02 from the discharge outlet of centrifuge 04 or other suitable sourc into the inlet of the crystallizer. The purpose of this is to provide sufilcient carrier for the abietic acid crystals and to produce a thin crystal slurry which can be eillciently handled in centrifuge 84.

The continuous crystallizer discharges by means of pipe 08 into centrifuge 04 wherein the crystalline abietic acid is separated from the mother liquor containing methyl fatty acid esters. Hot

water is introduced by pipe 05 into the discharge end of the centrifuge in order to purify the crystals and the contaminated water is discharged with th esters at the opposite end of the centrifuge.

The washed abietic acid crystals are discharged onto a conveyor by which they are transported to a. melting tank ll, this tank being provided with a dowtherm or another suitable heating coil. The abietic acid is melted and treated with live steam, introduced by pipe 80, to convert it into a product simulating rosin. For this purpose, a temperature of about 285 C. is preferably maintained in the melting tank, but it should be clearly understood that other temperatures within the range of from 250 C.-350 C. may also be used. The time 'of heating and the amount of steaming will depend on the desired properties of the final product.

The distillate containing small amounts of abietic acid, fatty acids and esters passes from the melting tank by means of pip 09 into a condenser 00 where it is condensed and discharged into a recovery system 82 by pipe 0|. The hot liquid resin residue is continuously drawn of! through pipe 93 into storage vessels 94.

The semi-crude esters leaving centrifuge 04 by pipe 05 (after a fixed portion has been removed for recycling to continuous crystallizer 0|) how at a predetermined rate to a preheater 96 where they are heated to a temperature of about 310 C. The preheated esters are discharged by pipe 01 into a fractionating column where they are distilled by means of steam which is introduced through pipe I00. The distillation is carried out at atemperature of from 220 C. to 250 C. and at an absolute .pressure of about 10 to 50 millimeters of mercury. The distilled esters ilow continuously by pipe IOI into partial condenser I02 wherein substantially all of the esters are condensed. The steam, non-condensible gases and a relatively minor amount of esters are conveyed by pipe I03 into entrainment separator I04 where the steam and non-condensible gases are sepa-' rated and discharged by pipe I05 into pipe I00 leading to vacuum system I01. The steam and non-condensible gases are exhausted from the vacuum system by way of discharge pipe I08.

The esters condensed in the entrainment sepa rator I 04 and in partial condenser I 02 drain into split flow box III by means of pipes I08 and IIO respectively and a fixed portion of this condensate is recycled as reflux to fractionating column 00 by way of pipe II 2. The remainder fiows from split fiow box III into the methyl esters storage vessel I It by means of pipe III.

13' Thebottomsoveriiowconfromi'racissimilartotheonejustdescribed. Inthissystem the bottoms are subjected to vacuum steam distillation at an absolute pressure of iron mm. to 50 mm. of mercury and at a temperatme of from 250' C. to 300 C. The resulting intermediate ester fraction is recycled at a p edeterminedratetotheesteriiicationtanklibymeans of pipes II and respectively and the steam and non-condensible gases flow out of the fractionating system by means of pipes I" and III for ultimate disposal by the vacuum system Ill.

The bottoms from the distillation carried out in the fractionating system "0 are discharged through pipe 9 into skippin column III. Steam is introduced b pipe iii andit passes up the column countercurrently to the flow of the 'bottoms being fed into the top of the column.

The resin oil thus obtained. together with steam and non-condensible gm. passes into a partial condenser (not shown) wherein the resin oil is condensed and discharged into suitable evacuated storage vessel i2! by pipe I22. The steam and non-condensible gases flow through an entrainment separator (not shown) and are finally conveyed via pipe 8 to vacuumsystem III for disposal The residue from the stripping operation which consists of a high boiling pitch flows continuously out of stripping column l2. into storage vessels I! by means of pip I". e

The conditions or operation of the more importantsteps ottheproceswillnmvbediscussed in detail.

r raaoadniu en The crude oil is preferably dried by distillingit under reduced presure at a temperature of from 120 C. to 280 6., but the invention is not restricted thereto as other known methods of achieving this result may be emp yed- Talloilrefim'agstep lnitial'abieticacidstep Inthisstepofthepmmthedistllledtalloil iscooledtoabout23'C.,butlowertemperatures maybeemployedifihsired. Asindicatedearlier in the present this step may be omittedbutwhencarryingonttheprooessbatchwise,weprefertoincludeitasbydoingsothe yieldofthepmductksubstantially Esterificaflon step Thisreactioniscarriedoutinflieof amineralaeidcatalymprefcrabhHCLandat a'teinperature which falls within therangeofi'rom40(2.to600.,buthigheror slightlylowermayahobemed.

'I'hearnountofaeidcatalystaddeddoesnot appeartobecriticalbutforeconolnicreason's andtofacilitateitsremovaliromtheesteriiied mixture,'it is preferably limited to about 3% to 6% by weight of the distilled tall oil treated.

Me hyl. ethy pror op p l. utyl. isobutyl. amylorisoamylandmixturestbereofmaybe selectivelyreactedwiththefattyacidsoftalloil' to form the corresponding esters. The'amount of alcohol required for substantially complete esteriflcation varies with the composition of the tall 10 oil and also with the particular alcohol and cataunderstood that the invention is not restricted l5 thereto.

Washing step This operation is designed to remove the excess alcohol and acid so that the mixture will be more adapted for distillation. Moreover, it has as its purpose the recovery, of the unreacted alcohol so that it can be reused in the process. Although it is desirable to remove the alcohol and acid as completely as possible, there is nothany suitable means for achieving this end may beemployed.

\ Fractionation step The distillation of the methyl esters is carried out at a temperature of from 220 C. to 250 C.

tion is continued at a temperature of from 250 C.

to 300 C. and at an absolute pressure within the above range. An intermediate fraction. is thus separated consistingoi abietic acid and a relatively small amount of methyl esters.

In the separation of the esters of other alcohols,

the optimum distillation temperature and pressure will vary with the alcohol used in the esteriflcation step.

Second abietic acid crystallization step The abletic acid content of the intermediate fraction is preferably crystallized from its mother liquor by cooling the fraction to room temperature. Lower temperatures may also be utilized provided the intermediate fraction is not cooled to the point where the resulting slurry is too'viscans for emcient handling in the centrifuge.

Separation of abietic acid crystals from mother liquor and purification thereof Theabieticacidcrystalsareseparatedfrom their mother liquor by centrifuging (or in any other suitable manner) and then mauled by washing while in the centrifuge with hot water, no alcohol, or a water soluble organicsolvent. This method of separation and purification is also applied to the abietic crystals which are recovered from the distilled tall oil.

a Mother liquor treatment after separation of abietic acid crystals As indicated above the abietic acid mother llquormaybemixed withretlnedtalloil ofrcduced abietic acid content, and then reworked,

or the mother liquor may be accumulated and resin oil. This treatment involves heating the ing particularly critical about this step so that' aaa'aooo mother liquor at a temperature of from 250' C.

to 300 C. for a period of from about 8 hours to about it an hour with simultaneous steaming or partial distillation under reduced pressure, the time of heating varying inversely with the temperature. Within these limits we preferto carry out the heat treatment at a temperature of about 280 C. for a period of about 2 hours. As an alternative to the foregoingprocedure, the treatment may be carried out in steps, that is, the mother liquor may be heated to a temperature within the above range and then subjected to partial steam or vacuum distillation. The resulting undistilled product consisting of a viscous resin oil is then cooled in an inert atmosphere to room temperature.

Abietic acid heat treatment with vacuum distillationremoves small amounts abietic acid in the form of non-tacky, free flowing flakes varying in thickness from 0.001 to 0.5 of

an inch, said flakes being further characterized I bythe following properties:

of rosin oils, fatty acids, methyl esters and other volatile impurities and at the same time converts the crystalline abietic acidinto a brittle glassy product simulating commercial rosin in appearance and chemical properties.

The heat treatment is preferably carried out in such a manner that about 20% g by weight of the abietic acid treated is distilled. The invention, however, is not limited thereto as greater or smaller amounts may be distilled, the extent of distillation being controlled by the properties desiredin the final product.

Where abietic acid is used in the specification and claims, it is to be understood that this expression covers tall oil resin acids, that is, abietic acid, abietic acid anhydride, abietic acid isomers and mixtures of these materials. Also, where the expression aliphatic alcohol is used in the claims, it is to be understood that an aliphatic alcohol having from 1 to 5 carbon atoms is intended.

As many widely different embodiments of this invention may be, made without departing from the spirit and the scope thereof, it is to be understood that we do not limit ourselves to. the speciflc embodiments thereof except as defined in the appended'claims.

We claim: I 1. As a new product, a heat treated tall oil abietic acid having substantially the following properties:

2. As a new product, a heat treated tall oil abietic acid in the form of non-tacky, free flowing flakes, said flakes being further characterized by the following properties:

Acid No. 173.9 Rosin, acid No. 171.6 Saponiflcation No. 175.7 Unsaponiflables per cent 3.1 Softening point (A. S. T. M. ball and ring method) C-.. 88 Color x 4. As a new product, a heat treated tall oil abietic acid simulating commercial rosin having the following properties:

Acid number 172.5-178 Softening point (AS'I'M ball and ring method) C 85-87 Unsaponiflable content per cent 2.6-4.4

5. As a new product, a heat treated tall oil abietic acid simulating commercial rosin having the following properties:

Acid number 175 Softening point (ASTM ball and ring method) a 0.- 8'1 Unsaponiflable content per cent 2.3

6. A process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponiflable organic material; converting the fatty acids in said refined tall oil into alkyl esters by selective esteriflcation with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a flnal fraction comprising a resinous pitch; cooling said intermediate fraction. to crystallize abietic acid therefrom and thereupon recovering said crystallized abietic acid.

7. A process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponiflable' organic material; converting the fatty acids in said refined tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comhour while subjectingthe molten product during at least the final stages of said heat treatment to partial distillation and thereby producing a brittle glassy residue simulating commercial rosin and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product.

8. The process deflned inclaim 7,'wherein, the partial distillation is carried out -under reduced pressure.

9. The process defined in claim 7, wherein the partial distillation is accomplished with the aid of steam.

10. The process defined in claim 7, wherein the partial distillation is carried out in the final stages of the heat treatment.

11. The process defined in claim 7, wherein the separated abietic acid is washed to remove impurities prior to being subjected to heat treatment and partial distillation.

12. A process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said refined tall 011 into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction com prising abietic acid and relatively small proportion of said alkyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize abietic acid contained therein; separating and purifying said abietic acid by washing; and heating the purified abietic acid to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about hour while passing steam through the molten product and thereby producing a brittle glassy residue simulating commercial rosin, and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product.

13. A process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said refined tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize abietic acid contained therein; separating and purifying said abietic acid by washing; and heating the purified abietic acid to a temperature of about 285 C. for a period of about hour while passing steam into the molten product and thereby producing a brittle glassy residue simulating commercial rosin and a distillate in an amount equivalent to about 12% by weight of said molten product.

14. The process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce amount equivalent to about 41% by weight of said molten product.

15. The process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize abietic acid contained therein;

a fraction consisting essentially of said'alkyl arating and purifying said abietic acid by wash- 1 ing; and heating the purified albietic acid to atemperature of about 285 C. for a period of about 3 hours while passing steam into the molten product and thereby producing a residue which upon cooling yields a brittle glassy solid simuseparating and purifying said abietic acid by washing; and heating the purified abietic acid to a temperature of about 285 C. for a period of about 4 hours while passing steam into the molten product and thereby producing a residue which upon cooling yields a brittle glassy solid simulating commercial rosin, and a distillate in an amount equivalent to about 23% by weight of said molten product.

16. The process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to5 carbon atoms; fractionally distilling the resulting ester mixture to produce 'a. fraction consisting essentially of said alkyl arating and purifying said abietic acid by washing; and heating the purified abietic acid to a temperature of from 250 c. to 350" c. for a period of about 8 hours to about hour while passing steam into the molten product and thereby producing a residue which upon cooling yields a brittle glassy solid simulating commercial rosin, and a distillate in an amount equivalent to about 20% by weight of said molten product.

17. The process of producing valuable products from crude tall oil, which comprise refining said tall oil without substantial removal 'of unsaponifiable organic material; converting the fatty acids in said tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize abietic acid contained therein; separating and purifying said abietic acid by washing; and heating the purified abietic acid to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about hour while subjecting the purified product to vacuum distillation and thereby producing'a residue which upon cooling yields a brittle glassy solid simu-' lating commercial rosin, and a distillate in an amount equivalent to about 20% by weight of said product.

18. The process of producing valuable products lating commercial rosin, and a distillate in an 76 from crude tall oil, which comprises refining said tall'oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said refined tall oil into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize said abietic acid therefrom; centrifuging the resulting abietic acid slurry to separate the mother liquor therefrom; purifying said abietic acid by washing with hot water; heating said purified abietic acid to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about /2 hour while passing steam through the molten product and thereby producing a molten residue and a distillate in an amount equivalent to about 11% to about 41 by weight of said molten product; and thereupon flaking said molten residue by rapidly chilling same in thin layers.

19. A process of producing valuable products from crude oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said refined tall oil into methyl esters by selective esterification with methanol; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said methyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said methyl esters, and a final fraction comprising resinous pitch; cooling said intermediate fraction to form a crystalline slurry of abietic acid; centrifuging said slurry to separate the abietic acid from its mother liquor; purifying said abietic acid by washing with methanol; and then heating said purified abietic acid to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about hour while passing steam through the molten product and thereby producing a brittle glassy residue simulating commercial rosin and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product.

20. The process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; converting the fatty acids in said refined tall oil into methyl esters by selective esterification with methanol; removing the excess methanol from the resulting ester mixture by washing with water; fractionally distilling the washed ester mixture to produce a fraction consisting essentially of said methyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said methyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to form a crystalline slurry of abietic acid; separating the abietic acid from its mother liquor by centrifuging said slurry; purifying the separated abietic acid by wishing with methanol; and thereupon heating said purified abietic acid to a. temperature of from 250 C. to 350 C. fora period of about 8 hours to about hour while v passing steam through the molten product and thereby producing a brittle glassy residue simulating commercial rosin and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product, said crude tall oil being refined by vacuum steam distillation at a temperature of from 240 C. to 300 C.

21. A process of producing valuable products from refined tall 011 containing substantial amounts of unsaponifiable organic material; which comprises converting the fatty'acids contained in said refined tall oil into alkyl esters by selective esterifictaion with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; washing the resulting ester mixture with water to remove excess alcohol; fractionally distilling the washed ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters,

and a final fraction comprising a resinous pitch;

cooling said intermediate fraction to form a slurry of crystallized abietic acid; separating said abietic acid from its mother liquor; purifying said abietic-acid by washing; and heating the purified abietic acid to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about A hour while passing steam through the molten product and thereby producing a brittle glassy residue simulating commercial rosin and-a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product.

22. A process of producing valuable products from crude tall oil, which comprises refining said tall oil without substantial removal of unsaponifiable organic material; cooling said refined tall oil to crystallize abietic acid therefrom; separating said crystallized abietic acid from the resulting mother liquor; converting the fatty acids of said mother liquor into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize abietic acid and recovering said crystallized abietic acid.

23. The process of producing valuable products from crude tall oil, which comprises refining said tall oil by vacuum steam distillation without substantial 'removal of unsaponifiable organic material: cooling said refined tall oil to crystallize abietic acid therefrom; separating said crystallized abietic acid from the resulting mother liquor; converting the fatty acids of said mother liquor into alkyl esters by selective esterification with a monohydric aliphatic alcohol having from 1 to 5 carbon atoms; fractionally distilling the resulting ester mixture to produce a. fraction consisting essentially of said alkyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said alkyl esters, and a final fraction comprising'a resinous pitch; cooling said intermediate fraction to crystallize abietic acid and recovering said crystallized abietic acid.

24. The process of producing valuable products from crude tall oil, which comprises refining said tall oil by vacuum steam distillation without substantial removal of unsaponifiable organic material; cooling said refined tall oil to crystallize abietic acid therefrom; separating said crystallized abietic acid from the resulting mother liquor; converting the fatty acids of said mother liquor into methyl esters by selective esterificaj tion with methanol; fractionally distilling the resuiting ester mixture to produce a fraction consisting essentially of said methyl esters, an intermediate fraction comprising abietic acid and a relatively small proportion of said methyl esters, and a final fraction comprising a resinous pitch; cooling said intermediate fraction to crystallize aibietic acid and recovering said crystallized abietic acid. Y

25. The process defined in claim 24 wherein the recovered abietic acid is heated to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about V2 hour while subjecting the molten product during at least the final stages of said heat treatment to partial distillation and thereby producing a brittle glassy residue simulating commercial rosin and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product.

26. A continuous process of producing valuable products from crude tall oil, which comprises subjecting said tall oil to continuous flash distillation to remove moisture therefrom; refining said dried tall oil without substantial removal of unsaponifiable organic material by continuous vacuum steam distillation; condensing and mixing said refined tall oil with methanal and an albietic acid fraction comprising abietic acid and a relatively small proportion of methyl tall oil fatty acid esters; selectively esterifying the fatty acids of said refined tall oil by reaction with said methanol; cooling the resulting reaction product to produce a slurry of crystallized abietic acid; recovering said crystallized abietic acid from its mother liquor and continuously fractionally distilling said mother liquor to produce a fraction consisting of methyl tall oil fatty acid esters, an abietic acid fraction comprising abietic acid and a relatively small proportion of methyl tall oil fatty acid esters and a final fraction comprising a viscous resin oil, said abietic acid fraction being continuously recycled for reuse in the esterification step of the process. a

27. The process defined in claim 26, wherein the recovered abietic acid is continuously heated to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about y hour while subjecting the molten product during at least the final stages of said heat treatment to partial by continuously producing a brittle glassy residu simulating commercial rosin and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product.

29. The process defined in claim 26, wherein the abietic acid recovered is continuously heated to a temperature of from 250 C. to 350 C. for a period of about 8 hours to about ,4 hour while subjecting said molten product to vacuum distillation and thereby continuously producing a brittle glassy residue simulating commercial rosin and a distillate in an amount equivalent to about 11% to about 41% by weight of said molten product. 4

30. The process defined in claim 28, wherein the steam is passed into the molten product at a rate such that about 20% by weight of the molten product is continuously distilled.

31. The process defined in claim 29, wherein the vacuum distillation is so controlled that about 20% by weight of the molten product is continuously distilled.

GEORGE E. TAYIDR. JOE S. ME'ICALF.

LEWIS-L. BRANSCOMIB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,114,278 Mariner Oct. 20, 1914 1,643,276 Logan Sept. 20, 192'! 2,240,365 Dreger Apr. 29, 1941 2,275,075 Gayer Mar. 3, 1942 2,334,762 Hasselstrom NOV. 23, 1943 2,384,062 Auer Sept. 4, 1945 Certificate of Correction Patent No. 2,487,000 November 1, 1949 GEORGE E. TAYLOR ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 7, line 27, and column 8, line 39, for the numeral 12.2 read 442.2; column 7, line 48, for 41" read +41; columns '9 and 10, in the table, sixth column thereof, sixth line under the heading, for 178.2 read 168.2;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in thePatent Ofiice. Signed and sealed this 14th day of March, A. D. 1950.

THOMAS E. MURPHY, v

1 7 Assistant Oommidsianer of Patents.

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