US3926936A

US3926936A - Process for manufacturing valuable products from tall oil pitch

Info

Publication number: US3926936A
Authority: US
Inventors: Timo Pellervo Lehtinen
Original assignee: OULO OSAKEYHTIO
Current assignee: OULO OSAKEYHTIO
Priority date: 1972-11-17
Filing date: 1973-11-15
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16
Also published as: SU587871A3; AT330925B; NL175432C; DE2356576A1; NO140799B; JPS5726319B2; FI49708B; FR2207185A1; GB1432853A; FI49708C; DE2356576C3; FR2207185B1; IT1003227B; DE2356576B2; SE383527C; NO140799C; JPS49133313A; NL7315842A; ATA962473A; PL87655B1

Abstract

Fatty acid and rosin, or a mixture of these, as well as hard pitch of a new type are manufactured starting from oil pitch produced in the distillation of tall oil, by a process wherein said tall oil pitch is initially heated, either as such or in a solvent, at a temperature of 200*-300*C together with an alkali reagent, said alkali comprising 5-25 % of the amount of pitch; the product thus obtained is acidified into oil having an acid value of 50-150; the oil obtained is distilled, either as such or after the removal of the salt produced in the acidification, at a pressure lower than 50 mm Hg; whereby there is obtained firstly a distillate with the acid value of 100-190 and which may be refined further e.g., by the known fraction distillation process at lowered pressure, and secondly a distillation residue with a softening point exceeding 50*C.

Description

United States Patent Lehtinen [75] Inventor: Timo Pellervo Lehtinen, Oulu,

Finland [73] Assignee: Oulo Osakeyhtio, Oulu, Finland 22 Filed: Nov. 15, 1973 [21] Appl. No.: 416,101

[30] Foreign Application Priority 'Data Nov. 17, 1972 Finland 3237/72 [52] US. Cl. 260/975; 260/103 [51] Int. Cl. C09F l/04 [58] Field of Search 260/975, 97.6, 100

[56] References Cited v UNITED STATES PATENTS 2,138,183 11/1938 Littman 260/100 2,276,517 3/1942 Segesseman w 260/97.6 2,334,762 11/1943 l-lasselstrom 260/975 2,530,810 11/1950 Christendon 260/97.6

PROCESS FOR MANUFACTURING VALUABLE PRODUCTS FROM TALL 01L PITCH Primary ExaminerLewis T. Jacobs Attorney, Agent, or FirmSchuyler, Birch, Swindler, McKie & Beckett 57 ABSTRACT Fatty acid and'rosin, or a mixture of these, as well as hard pitch of a new type are manufactured starting from oil pitch-produced in the distillation of tall 011, by a process wherein said tall oil pitch is initially heated, either as such or in a solvent, at a temperature of 200300C together with an alkali reagent, said alkali comprising 5-25 of the amount of pitch; the product thus obtained is acidified into oil having an acid value of 50-150; the oil obtained is distilled, either as such or after the removal of the salt produced in the acidification, at a pressure lower than 50 mm Hg; whereby there is' obtained firstly a distillate with the acid value of 100-190 and which may be refined further e.g., bythe known fraction distillation process at lowered pressure, and secondly a distillation residue with a softening point exceeding 50C.

Claims, No Drawings I PROCESS FOR MANUFACTURING VALUABLE PRODUCTS FROM TALL OIL PITCH BACKGROUND OFTI-IE INVENTION 5-10 tall oil fatty acids and a small amount of rosin-containing oils (30-35 tall oil rosin (30-35 and as a distillation residue, tall oil pitch (-30 Only the second and the third products are valuable raw materials used by the chemical industry. In most distilleries at least the bulk of the fore distillate and the pitch is burned.

In recent years the sulfate cellulose industry has considerably increased the use of hard wood, mainly birch, in pulp production. This has resulted in a worsening of the quality of crude tall oil. In distilleries this is manifested in, for example, an increased yield of pitch, which naturally weakens the economic profitability of the entire distillation. Thus, there is also an increasing need for improvements in the utilization of the tall oil produced.

SUMMARY OF THE INVENTION The present invention relates to a process of the character once described, which comprises heating of the tall oil pitch at a temperature of 200300C together with a-basic reagent, the base rate being 5-25 of the amount of pitch, acidifying the reaction product thereby obtained into oil having an acid value of 50-l50, distilling the obtained oil under a pressure of less than 50 mm Hg to get, a distillate, 10-70 of which the acid value is ,100-190 and which can be refined further by the previously known fraction distillation process under a lowered pressure, and a distillation residue of which the softening point (ball and ring) is not lower than 50C.

Insuch a process the oil pitch may be heated with the alkali reagent either as such or in a solvent. Likewise the oil obtained after acidifying may be distilled either as such or after the removal of the salt produced in the acidification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention opens new possibilities for point (ball and ring) of 60-90C and which can be obtained ash-free when desired. A typical analysis of the distillate is as follows:

Acid value 150-160 saponification value 155-165 Rosin acids, L. 30-50 Unsaponifiables;-% l0-20 Color, Gardner l0-l2 The invention is based on the observation that the difference between the saponification and acid values of tall oil pitch is considerably high. This difference, which is also called the ester number, is illustrated in the following table, for which quality samples of the pitch produced by three European tall oil distilleries have been selected arbitrarily:

A B C Acid value 35 40 3O saponification value 95 Ester number 55 60 65 The real incentive for this invention was, however, given by the observation that when the saponification of tall oil pitch is carried out under very drastic conditions, for example, by treating pitch with alkali 10-15 for 2 hours at 230C, strongly bonded acids on which a mild or moderately drastic saponification, such as is used, for example, in determining the saponification value, has no noteworthy effect, takes place to a surprisingly great extent. As a result of the said rigorous treatment, acids are released to such an extent that the real saponification value of pitch rises to about -140.

What are these compounds difficult to decompose? Some of them are obviously compounds which have been present already in the initial crude tall oil and which have not been decomposed by the conditions of sulfate cellulose digestion. However, it is quite probable that specifically the bonding of rosin acids into compounds difficult to saponify takes place during the first stage of tall oil distillation, in the so-called pitch column, according to the following mechanism: Rosin acid anhydrides are created as the first intermediates under the influence of high temperature when dehydration takes place, and these rosin acid anhydrides for their part react very easily with alcohols so that one half of an anhydride becomes esterified with the alcohol in question, while the other half is released as rosin acid:

The sulfuric acid residues present in the crude tall oil accelerate the said reaction catalytically. The presented reaction mechanism is supported by the observation that, in spite of favorable conditions, tall oil pitch contains practically no rosin acid anydrides. This is due to the fact that the rosin acid anhydride is only a momentary intermediate product which, immediately upon its formation, participates in the esterification reaction described above. Only after the alcohols present in the pitch have become exhausted, do stable anhydrides begin to be produced in it.

The following table illustrates the influence of saponification conditions on the release of these strongly bonded acids:

An advantageous temperature for the saponification of pitch is 220250C. At temperatures lower than this the saponification remains incomplete and, furthermore, the viscosity of the pitch soap is so great that mixing becomes difficult and is almost impossible at temperatures under 200C. At temperatures above 250C. saponification is accelerated, but the decarboxylation and splitting reactions of the acids are simultaneously fortified.

Even a shorter reaction period than 2 hours would be sufficient for mere saponification. The importance of the long reaction period mainly lies in that, when it is long, dehydration of alcohols, mainly sterols, released from the esters takes place to a considerable extent, in which case, when water becomes splitted, they form hydrocarbons which will not become rebonded to acids during the distillation as free sterols would.

The requisite amount of alkali depends to some extent on the quality of the pitch and is usually -15 of the amount of pitch. The alkali can be added either as such or as a 50 water solution, for example. The addition can already be started, when so desired, at a temperature of 100-1S0C As the addition progresses, the temperature of the pitch is raised so much that increased viscosity will not disturb the mixing. The alkali can just as well be added at the reaction temperature, e.g., 230C. Adding the alkali as a water-free powder isadvantageous because foaming does not then take place nearly as much as when using a water solution of the alkali. The acidification of the produced pitch soap, in order to release the fatty and rosin acids, can take place either while the soap is hot or by cooling the soap and dissolving it as granules in hot water for acidification.

When using the first alternative it is preferable to cool the pitch soap immediately after the saponification reaction to a temperature at which mixing is just barely possible, i.e., usually to about 200C. The acidification can be carried out with, for example, a 30-50 sulfuric acid solution. The viscosity of the reaction mixture begins to lower sharply after even a small acid addition and, consequently, the temperature can be lowered during the acidification so that at the end of the acidification it may be 150C, for example. When the temperature lowers, removing water by evaporation is complicated, for which reason it is preferable to use vacuum drying at the end. For two reasons it is advantageous to use acid at a rate slightly lower than the theoretical one: excess sulfuric acid causes corrosion problems and, on the other hand, it catalyzes the reesterification of the released acids.

The latter acidification process, which takes place in a water solution at a temperature below 100C, is more advantageous than the former in the respect that there are no foaming problems and, on the other hand, the isomerization of valuable products, mainly rosin acids, is less.

A third possibility is to achieve the alkali treatment of pitch in a suitable solvent, e.g., diethylene glycol, in which case the temperature of the reaction mixture can be lowered to below 100C before beginning the acidification, without the viscosity preventing it.

The rest of the process according to this invention can be arranged in its simplest form so that the oil obtained by acidification after the alkali treatment and which contains the alkali salt produced in the acidification is distilled over by a rapid vacuum distillation (e.g., 1-5 mm Hg), in which case the distillate yield is 30-40 the bottom temperature rising to about 300C. Within the bottom temperature range (300300C) the yield of a distillate which has a neutral substance content of about 50 e.g., hydrocarbons produced from sterols by dehydration, is still about 10 The alkali salt remains in the distillation residue, from which it can, when so desired, be regenerated by, for example, burning, which is possible in, for example, sulfate cellulose plants.

When desired, the alkali salt can be removed before distillation, in which case the hard pitch obtained as a distillation residue is ash-free. Thus, most of the solid, crystalline Na SO can be removed from dried oil by decantation or centrifugation. Even a water wash of the oil at C removes most of the alkali salt, but owing to the rather great viscosity of the oil, the separation of the layers is slower and less complete than in, for example, the wash of crude tall oil.

The most effective method for removing the alkali salt is to dissolve the oil released in the acidification in a suitable solvent with a polarity sufficient for complete dissolving. The alkali can be easily removed by centrifugation, filtration, or a water wash from this low-viscosity solution.

As a result of a process according to the present invention, the yield of distillate from tall oil pitch is 30-40 in a typical case, and'on the basis of a gravimetric analysis (alkali extraction and selective esterification) this distillate contains fatty acids 35-40 rosin acids 40-50 and neutral substance 12-16 The composition of the fatty acid portion (gaschromatography) is special in that the typical polyunsaturated fatty acids of tall oil (linoleic, cis-5,9,l2- octadecatrienoic, and cis-5,l 1,14-eicosatrienoic acids) have become transformed, under the influence of alkali treatment, almost quantitatively into their isomers with a conjugated diene system. According to a UV analysis, the fatty acid portion contains conjugated diene 30-40 and conjugated triene less than 1 According to a gaschromatographic analysis, the respective rosin acid portion is otherwise conventional except that the abietic/dehydroabietic acid ratio is lower than 1, while in a normal tall oil rosin it is usually higher than 1.

The neutral substance contains two main groups which are very distinct in a temperature programmed gaschromatographic analysis (SE 30 column). One group comprises the hydrocarbons produced as a result of the decarboxylation of the acids and the other decomposition products with low boiling points. The other group comprises the hydrocarbons produced as dehydration products from the sterols released from sterol esters. Obviously dehydration of sterols takes place both during the alkali treatment and during the acidification stage, for sulfuric acid is mentioned as an effective dehydration catalyst of secondary alcohols at 200C. The main component of these hydrocarbons is the A -diene C l-I produced from B-sitosterol and which is interesting even technologically owing to its conjugated diene structure, because by, for example, the Diels-Alder reaction it can be bonded with maleic anhydride or fumaric acid, in which case the obtained product is a usable additive in, for example, paper size.

The process which can be mainly considered for further refinement of the distillate is fractionating distillation at a lowered pressure. This can be carried out either as a completely separate line, in which case the th it h was i d to 150C A amount 6f 15 g f special characteristics of the obtained fatty acid and N OH as a 50 water l i was dd d to h i h rosin can be utilized, or alternatively the pitch distillate hil l i h temperature to rise to 200 during can be fed into the distillation of normal tall oil, either th additi Th temperature was i d to 230C d into the crude tall oil or the distillate after the pitch mixing was continued for 2 hours. The temperature of column. In this case the properties of the obtained the produced pitch soap was dropped to 200C and products only slightly deviate from the quality of conacidification was carried out with a 50 H 80 soluventional tall oil products. tion. As the acidification progressed, the viscosity of In fractionating distillation the light hydrocarbons the reaction mixture lowered and, consequently, the d up almost completely i h f di till Lik temperature of the acidification was 160C, at which wise the color components become trongly concen temperatlslre the removal Of Water WaS Satisfactory. trated in the fore distillate. Therefore a light-colored The p lfeaction u e was dried in a vacuum product with a high acid value and a low content of and dlstlned Over as h undel: lowered P unsaponifiables can easily be obtained from the fatty mm g) total l' eld 0f distillate was 50 and acid fraction. The hydrocarbons produced by dehydra- It was taken two fractlonsi tion from the sterols mainly end up in the rosin in fractionating distillation, if rosin is taken as a distillation Fraction 1 Fraction 2 residue. lfthe rosin is also taken as a distillate, a considerable proportion of the hydrocarbons in question in gggjgfifvm 52 33 the distillation residue. Acid value 163 80 In addition to the described distillate suitable for 323123;; value 2g 38 further refining, another, interesting product is ob Unsaponifiables,% 16 46 tained simultaneously from tall oil pitch, namely, hard l1 18 pitch produced as a distillation residue. In a typical case the proporties of this product are as follows:

Fraction lrepresents a very high-standard product suitable for further refinement. When the temperature Acid fl 1 at the bottom rose above 300C, a great amount of Saponification value 60-90 softening point r 30 neutral substance was distilled over, as indicated by the (bail and ring), "C 60- 0 analysis of Fraction 2. Ash, 0-2

There are numerouss uses for a product like this, EXAMPLE 2 specifically owing to its high softening point, for it is known that the obstacle to a wider use of tall pitch has been above all the softening of pitch.

The economic significance of this invention lies in 100 g of tall'oil pitch was heated to 200C. 15 g of NaOH as a 50 water solution was added to the pitch while raising the temperature to 230C during the addithat the inexpensive and easily obtainable tall or] pitch, 200cc g i s i gig zz fi gg gi gg gg fi which un HOW mostly been burned, can 40 tion, the final temperature being 160C. The obzained composed y Chemlcal treafmfem T P a slmple oil was dissolved in 100 ml of ether. The Na SO prooverdistillation the yield of distillate from it is 30-40 duced in the acidification was washed away with water and the distillate can be refined further by fractionating and the ether wasevaporated' The acid value of the tan distillation into fatty acids and rosin, and in that simuloil was 1 19, its saponification value 124 and its rosin taneously so-called hard pitch of an entirely new type is i content 31 w the oil was histilled over Produced y the Process at a rate of under a lowered pressure (3 mm Hg), the yield of distil- On an industrial scale it is preferable to carry out the late was 40 and the analysis of the distillate as folhot saponification, acidification, and overdistillation of lows; tall oil pitch according to this invention as a continuous process as far as possible. In this manner it is possible to Acid value I 57 better control the disadvantages due to foaming and, saponification value 162 on the other hand, when the residence times are short- 52:22:22,32 $2 ened the reverse rebonding reactions of the released Color to acids remain minor. Continuous-working overdistilla-. tion must be carried out under the lowest possible pres- 55 sure, in any case, under 50 mm Hg.

Examples: The simultaneous yield of distillation residue was and its analysis as follows:

The'acid value of the tall oil pitch used in the follow- 60 ing examples was 39 and its saponification value 96. In Acid value 43 the analyses, the rosin acid content was determined by g ff l l" 94 the Linder-Persson method, the softening point by the Alt i point ac ifs ball and ring method, and the color in Gardner units.

EXAMPLE 1 EXAMPLE 3 l00 g of tall oil pitch was placed in a flask provided The saponification and the acidification of tall oil with a mixer and a thermometer. The temperature of pitch wa carried ut in h same way as in Example 2 7 except that the 2-hour hot saponification took place at a lower temperature, 200C. overdistillation was not carried out because the acid value of the obtained oil was only 72, its saponification value 99, and its rosin acid content 20 This indicates that the saponification conditions used were too mild.

EXAMPLE 4 100 g of tall oil pitch was heated to 200C. 10 g of solid, ground NaOH was added-to the pitch in small batches while the temperature was raised to 250C. Mixing was continued for 2 hours at 250C, and thereafter the vacuum distillation apparatus was connected to the reaction vessel for 15 minutes. During this period light neutral substance was distilled over, in an amount of 2 of the reaction mixture. The acidification of the pitch soap and the removal of the Na SO took place as indicated in Example 2. The acid value of the obtained oil was 105 and its rosin acid content 28 The yield of distillate from the overdistillation of the oil (3 mm Hg) was 37 and its analysis as follows:

Acid value 152 Saponification value 158 Rosin acids, 41 Unsaponifiables, 18 Color 12 The simultaneous yield of distillation residue was 63 and its analysis as follows:

Acid value 36 Saponification value 60 Softening point, "C 68 Ash, 0.1

EXAMPLE 100 g of tall oil pitch was treated as explained in Example 1. An amount of 100 ml of solvent petroleum was added to the oil after acidification (boiling point 150-200C, aromatics l4 and the Na SO produced in the acidification was washed away with water. The yield of distillate obtained by overdistillation under a lowered pressure (3 mm Hg) was 35 Acid value 163 Saponification value 164 Rosin acids, 49 Unsaponifiables, 12 Color The yield of distillation residue was about 65 and its analysis as follows:

Acid value 43 Softening point, C 90 Ash, 1.7 lnsolubles in petroleum ether, 58

EXAMPLE 6 100 g of tall oil pitch, 100 ml of diethylene glycol, and g of NaOH was placed in reaction flask provided with a mixer and a thermometer. The temperature of the mixture was raised to 230C and mixing was continued for 2 hours. The reaction mixture was cooled to 90C and the pitch soap was acidified with a 30 H solution. The glycol was washed away with water. The acid value of the obtained oil was 96.

EXAMPLE 7 2500 g of tall oil pitch was placed in a 5 1 reaction flask provided with a mixer and a thermometer. The temperature of ,the pitch was raised to 230C, and 250 g of powdered NaOH was added to the pitch in the course of about half an hour. Mixing was continued for 2 hours at 230C. The reaction mixture at 230C was poured into an aluminium foil mold and allowed to cool. The cooled, hard pitch soap was crushed into pieces and dissolved in about 5 l of water. The dissolution took place easily when heated. The obtained soap solution was acidified with a 30 H 80 solution and the produced oil was washed with water (3 times 2 liters). The acid value of the obtained oil was 104 and its ash content 5 so that the washing of Na SO had not been nearly complete. The yield of the overdistillation was 35 and its analysis as follows:

Acid value 159 Rosin acids, 36 Color 11 Fraction 1 Fraction 2 Fraction 3 Residue Boiling point,C 96-190 190-215 215-225 Rate, 8.5 31.9 27.1 32.5 Acid value 111 183 173 114 Rosin acids, 3 15 51 43 Color 1 1 6 5 17 Even such a modest attempt at fractionation indicates that the neutral substances and color components become concentrated in the fore distillate and the distillation residue, and consequently, high-standard products are easily obtained in an eflective fraction distillation apparatus from the actual valuable products, i.e., fatty acid and rosin.

EXAMPLE 8 A tall oil pitch treatment according to the invention was carried out on a semi-technological scale as follows:

1200 kg of tall oil pitch (acid value 25, saponification value 109) was pumped into a reactor of 3 m The temperature of the pitch was controlled at 250C, and kg of NaOH (as a 50 water solution) was added to it. At first the alkali solution could be added rapidly but gradually the foaming of the pitch soap increased, the evaporation of water becoming more difficult as a result of increasing viscosity, and the feeding of the alkali had to be slowed down. By raising the temperature of the reaction mixture to 260270C and by increasing the rotary velocity of the mixer, the foaming could, however, be easily controlled. The addition of the alkali took about four hours.

lower level and provided-with -a mixer and containing about 2000 l of water at 30C. The pitch soap was dissolved in the water rapidly and completely. No foaming or spitting took place. The final temperature of the produced pitch soap solution was about 90C.

The pitch soap solution was acidified with an equivalent amount of a 30 sulfuric acid. The NaSO -containing water layer and the oil produced in the acidification became easily and sharply separated from each other at 90C. About 90 of the Na SO produced in the acidification ended up in the water layer.

Since the separation of the layers in the next water wash was slow owing to the decreased density difference, 400 l of xylene was added to the oil. Thereafter the separation of the oil and the water layer was easy. The xylene solution of oil was washed twice with 1,000 l of water.

The xylene was removed from the oil by an overdistillation carried out under a pressure of about 100 mm Hg. At the same time the oil was obtained completely water-free since the remanent water was distilled together with the xylene. The analysis of the obtained oil was as follows:

Acid value 98 Saponification value 1 l9 Rosin acids, 16 Ash, 0.2 Free H 80 0.001

The oil was fed into a continuous-working distillation column. The feeding rate varied within the range of 40-70 kg/h. The pressure at the top of the column was 2-4 mm Hg and at the bottom 5-7 mm Hg. In addition,

steam at the rate of 2-3 of the feed was directed into 1 I the column. The rate of distillate taken was about 30 of the feed. The average analysis of the distillate was as follows:

Acid value 158 saponification value 162 Rosin acids, 26

Unsaponifiables, Color, Gardner The yield of distillation residue was on the average 70 and it was hard pitch with the following typical analysis:

Acid value 50 saponification value 80 Softening point, C 67 Ash. 0.3

Tosaveitime, it is advantageous to carry out the alkali treatment within the temperature range of 250300C, although decomposition reactions naturally occur to some extent even within this range.

Directing the pitch soap at the temperature of about 250C into water is a very easy and rapid method, ad-

vantageous in terms of thermal economy, of producing a water, solution of pitch soap suitablefor acidification. I In the overdistillation of the oil obtained from the acidification it is preferable to use a distillation apparatus in which the losses of pressure between the bottom and the top are small. Feeding steam into the distillation apparatus is advantageous, for it decreases bonding reactions of acids during the distillation (esterification, anhydride formation, etc.).

What is claimed is:

1. A process for the manufacture of products from tall oil pitch produced in the distillation of tall oil, comprising:

a. saponifying tall oil pitch by heating it at a temperature in the range 200-300C. together with an alkali saponification agent, the amount of said agent comprising 525% of the amount of pitch until a main portion of the sterols liberated from fatty and rosin acid esters have been converted to hydrocarbons by dehydration,

b. acidifying the reaction product thereby obtained to form an oil having an acid value in the range 50-1 50,

c. distilling the obtained oil under a pressure of less than 50 mm Hg to obtain a distillate, 1070%, of which the acid value is -190, and a distillation residue of which the softening point (ball and ring) is not lower than 50C.

2. A process according to claim 1 wherein the saponification of the tall oil pitch is conducted by heating tall oil pitch together with said saponification agent in the absence of substantial amounts of solvent for said tall oil pitch.

3. A process according to claim 1 wherein the saponification is conducted by heating said tall oil pitch together with said saponification agent in the presence of a solvent for said tall oil pitch.

4. A process according to claim 1 wherein the salt produced in acidification step (b) is retained in said obtained oil during distillation.

5. A process according to claim 1 wherein the salt produced in acidification step (b) is removed prior to distilling the obtained oil.

6. A process according to claim 1 wherein said tall oil pitch is heated together with said saponification agent at a temperature in the range 220225C.

7. A process according to claim 6 wherein said heating is sufiiciently rigorous to release acids from said tall oil pitch such that the real saponification value of said pitch rises to about -140.

8. The process of claim 7 wherein said heating is conducted for about 2 hours.

9. A process according to claim 1 wherein in step (a) the amount of said saponification agent is 720% and said temperature is in the range 230280C.;

in step (b) the saponified pitch soap melt is directed into water to obtain a pitch soap solution which is acidified into oil; and

in step (b) the alkali salt produced in the acidification is removed by a water wash prior to step (c).

12 distillation together with tall oil under a lowered pressure.

13. A process according to claim 12 wherein said distillate is fed into crude tall oil.

14. A process according to claim 12 wherein said distillate is fed into a distillate obtained from a pitch column.

Claims

1. A PROCESS FOR THE MANUFACTURE OF PRODUCTS FROM TALL OIL PITCH PRODUCED IN THE DISTILLATION OF TALL OIL, COMPRISING: A. SAPONIFYING TALL OIL PITCH BY HEATING IT AT A TEMPERATURE IN THE RANGE 200*-300*C. TOGETHER WITH AN ALKALI SAPONIFICATION AGENT, THE AMOUNT OF SAID AGENT COMPRISING 5-25% OF THE AMOUNT OF PITCH UNTIL A MAIN PORTION OF THE STEROLS LIBERATED FROM FATTY AND ROSIN ACID ESTERS HAVE BEEN CONVERTED TO HYDROCARBONS BY DEHYDRATIONN, B. ACIDIFYING THE REACTION PRODUCT THEREBY OBTAINED TO FORM AN OIL HAVING AN ACID VALUE IN THE RANGE 50-150, C. DISTILLING THE OBTAINED A DISTILLATE, 10-70%, OF WHICH THE AC MM HG TO OBTAIN A DISTILLATE, 10-70%, OF WHICH THE ACID ID VALUE IS 100-190, AND A DISTILLATION RESIDUE OF WHICH THE SOFTENING POINT (BALL AND RING) IS NOT LOWER THAN 50*C.

6. A process according to claim 1 wherein said tall oil pitch is heated together with said saponification agent at a temperature in the range 220*-225*C.

7. A process according to claim 6 wherein said heating is sufficiently rigorous to release acids from said tall oil pitch such that the real saponification value of said pitch rises to about 120-140.

8. The process of claim 7 wherein said heating is conducted for about 2 hours.

9. A process according to claim 1 wherein in step (a) the amount of said saponification agent is 7-20% and said temperature is in the range 230*-280*C.; in step (b) the saponified pitch soap melt is directed into water to obtain a pitch soap solution which is acidified into oil; and in step (b) the alkali salt produced in the acidification is removed by a water wash prior to step (c).

10. A process according to claim 1 wherein a solvent is added to said obtained oil and the salt produced in the acidification is removed prior to step (c).

11. A process according to claim 1 wherein the distillate obtained in step (c) is capable of being fractionally distilled into fatty acids and rosins.

12. A process according to claim 1 wherein the distillate obtained in step (c) is further refined by fractional distillation together with tall oil under a lowered pressure.