US2854442A - Stabilized tall oil soap and floating soap products - Google Patents

Description

2 Sheets-Sheet 1 IIIIMwwNZ ,X m 160W mcmwonu TUWWULL. I imodwnz S N aow 9.252 .55505 c. K. CLARK Erm. STABILIZED TALL OIL SOAP AND FLOATING SOAP PRODUCTS Filed F`eb. s, 195s Sept. 30, 1958 mgm mctoo w25 :o 23.-. $252 Chcxes KClark, Rober? O. Nason,

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STABILIZED TALL OIL SOAP AND FLOATING SOAP PRODUCTS Filed Feb. 6, 195e 2 sheets-sheet 2 Time, Houra 4 Hopa-assed, Na Na-Szoz--u-n-nn- Unpmssd, 3% Nen- 5;

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United rates STABlLIZED TALL )IL SOAP AND FLGATING SOAP PRODUCTS Charles K. Clark and Robert 0. Nason, Crossett, Ark., assignors to CrossettChemical Company, a division of The Crossett Company, Crossett, Ark., a corporation of Arkansas Application February 6, 1958, Serial No. 714,461

l11.4 Claims. (Cl. 260-915) This invention relates to the manufacture of improved soap products from the black liquor resulting from digestion of pulpwood by the kraft or soda cooking processes. More specifically, this invention.l relates to the manufacture of floating soaps and tall oil soaps as byproducts of pulpwood digestion processes, which soaps are characterized, inter alia, by enhanced resistance to spontaneous heating.

It is well known in the pulp and paper arts that the black liquor produced in the kraft or soda cooking process contains, among other things, the sodium salts of -rosin acids and fatty acids. These salts or soaps separate `out or oat on top of the black liquor during evaporation to recover the alkali values therefrom. The crudefloating material obtained during the evaporation is known to the art by various names, e. g., floating soap, soap skimmings and the like.

Crude floating .soap is also a source of talloil. Con- Ventionally, in the production of tall oil from floating soap, thefloating soap is split with sulfuric acid to form tall oil and brine. The tall oil is separated out and saponied with aqueous sodium hydroxide. Alternatively, purification by well-known means may be introduced at one or more stages of the process of obtaining the Asodium tallate from `lioating` soap. For example, the floating soap may be puriiied before acidulationvor the tall oil may be purified before saponiiication. Al-

f though alkali metal hydroxides and other compounds may be employed for saponiiication of tall oil, lit has been found that only sodium tallate is satisfactory for use in the present invention land for this reason it is intended that any use of the expression tall oil soap in-this speciication and in the appended claimsfbeconstrued as sodium tallate.

`Floating soap vand tall oil soap have avnumber of irnportant industrial applications, oneof the more important uses at the present time being as an ingredient in oil well drilling uids (see United 4States Patent 2,468,658). For use as an ingredient in oil well drilling uids and for other industrial uses such as in soaps and lubricants, it is conventional practice to dry the oating soap or tall oil soap and to flake or otherwise com- Aminute the dried soap to form a particulate product. Floating soaps and tall oil soaps may be suitablyk dried Aby conventional techniques, for example, by spray drying, drum drying, pan drying, and by combinations of these expedients. Drum drying techniques, however, are normally preferred.

The oating soaps and tall oil soaps currently available are characterized by an outstanding disadvantage, viz., that of spontaneous heating during shipment and storage. In heating spontaneously, these materials undergo a rise in temperature to a level sufficiently above ambient temperatures to cause the particles of Viioating `soap or tall oil soap to fuse into a charred and useless 'ice yreducedbycompressing the soaps to eifectan'incre'ase in absolute density. When the compressed-productsare then coniminuted to form the particulate product desired by the art, such product is not only characterized 'by resistance to spontaneous heating, but is 'found to be substantially non-dusting and non-caking. Moreover, the compressed product is further characterized by 'an improved rate of water solubility when compared 'to the conventional unpressed soaps. Generally, the pressed products will be characterized by an absolutedensity of between about 0.95 g./cc. and L08 g./cc. l f

Now, in accordance with the present invention, it has been found that spontaneous heating in oating soap and in tall oil soap may be markedly reduced'by 'adding thereto a small or minor amount-of a compound selected from the group consisting of ammonium and alkali metal salts of thiosulfuric acid (H2S2O3). Conventional unpressed floating soap and tall oil soap -and the pressed materials treated in accordance with the processesiof the Iabove-identified copending applications are both lapplicable in and contemplated by the present invention. Although a very substantial improvement in stability against spontaneous heating has been obtained byvaddition of one of the above-identified stabilizers or inhibitors to conventional unpressed iioating soaps 'and tall oil soaps,

-a still greater reduction in spontaneous heating ymay lbe obtained by the dual treatment of adding such an inhibitor to conventional floating soap or tall oil-'soap and pressing the resulting mixture according to the pressing operation disclosed in the said copendingapplications. This dual treatment is preferred because, in addition to effecting a somewhat greater reduction in spontaneous heating, the pressing operation also gives aproduct having va higher bulk density, lesstendency toward caking and dusting and a product which is more readily dissolved in water, as more specifically 'described in the copending applications.

Generally described, therefore, the invention includes a soap product inhibited against spontaneous heating comprising a material selected from the groupconsisting o-f floating soap and tall oil soap obtained by concentration of black liquor resulting from pulpwood digestion processes and containing at least a substantial portion of the impurities naturally present therein and, yas -the sole essential inhibitor, a minor amount of 'a material selected from the group consisting of alkali metal "and ammonium salts of thiosulfuric acid.

Also generally described, the invention includes a'pro'cess for producing a soap product inhibitedagainst'spontaneous heating which comprises blendingwith awrnaterial selected from the group consisting `of Vfloating soap and tall oil soap obtained by concentration of :black liquor resulting from pulpwood digestion 'processes and containing yat least a substantial portion.offthenimpurities naturally present therein, as the sole essential inhibitor, a minor amount of a material selected from the group consisting of alkali metal andiammonium salts of thiosulfuric acid. As a further embodiment ofthe invention, the resulting blend of soap and inhibitor isfcompressed to increase the absolute densityxthereof kand kto thus produce a product of enhanced resistance to spontaneous heating, which possesses improved water solu- Patented Sept. 30, 1958 bility, and which is substantially non-dusting and noncaking.

The following examples illustrate preferred embodiments of the instant invention.

The accompanying drawings are related to Examples 3 and 6 and will be explained in connection therewith.

EXAMPLE 1 `blended mixture was fed between two revolving drums whose surfaces were maintained at a temperature of about 135 C.-150 C. The mixture was thus dried to a moisture content of about (usually being `1%-5 and then doctored off the drums in the form of very thin, hot, sticky, tlully and discontinuous films. The dried floating soap mixture fell onto a screw conveyor from which it was picked up by a blower and sent to a cyclone separator. The dried and cooled tloating soap mixture passed from the cyclone separator into multi-wall paper bags which were closed and sent to storage. Each bag was loaded with 50 pounds of the floating soap mixture.

In passing through the fan and cyclone separator in the presence of a large volume of air, the large plastic sticky, thin films of floating soap mixture coming from the drums were further dried, reduced in tackiness, cooled and disintegrated to a coarse powder in suitable form to be bagged. This product had a bulk density of 12-18 pounds per cubic foot.

Liquid additives which were soluble in water dissolved in the aqueous phase of the floating soap, and therefore these were dispersed without diiculty. Insoluble liquids became dispersed as a consequence of the emulsifying action of the floating soap. Insoluble solids were ground to a tine powder before blending in the floating soap. Salts and other soluble solids dissolved in the aqueous phase of the floating soap. Thus sodium thiosulfate, e. g., was incorporated by adding the crystals directly to the floating soap and agitating until a uniform blend was obtained.

EXAMPLE 2 Portions of the dried floating soap-inhibitor mixture from Example 1 above were obtained just prior to the aagging operation therein and further processed as folows.

This floating soap mixture was pressed into sheets of roughly 1,45" thickness by passing same between two op posingS" diameter steel pressure rolls. The surfaces of the rolls were maintained at a temperature of about 40 C., which is approximately the temperature of the floating soap mixture discharging from the cyclone in Example l. Then the sheets were broken up into relatively small flakes all of which passed a screen having openings. This gave a compressed floating soap mixture having a bulk density of about 35 pounds per cubic foot and an absolute density of approximately 1.07 grams per cubic centimeter.

One roll was rotated by conventional driving means at a speed of about 4 R. P. M. The opposing roll idled and was rotated merely by the friction imparted by the driven roll through the floating soap mixture being pressed, the idling roll rotating at a speed slightly less than that of the driven roll.

In order to determine the comparative effect on spontaneous heating obtained by adding various inhibitors to oating soapin accordance with Example l above and by the dual treatment of adding various inhibitors to floating soapand pressing the resulting mixture in accordance with Example 2 above, the products of Example 1 "4 and the products of Example 2 were evaluated by the Mackay test in the manner disclosed in Example 3 below.

EXAMPLE 3 Spontaneous healing tests The Mackay test, with modifications indicated below, was employed on samples of the various products made according to Examples 1 and 2 above and their tendency to heat spontaneously thereby measured. This is a stand ard accelerated test originally developed for determining the spontaneous heating tendency of oils. See Scott, Standard .Methods of Chemical Analysis, 5th edition, New York: D. Van Nostrand Co., Inc., page 1782.

In order to adapt the Mackay test to better meet the testing requirements of this invention, the test sample was placed in a wire gauze basket made of stainless steel and the basket was suspended in an air jacket immersed in a constant temperature oil bath. One end of a thermocouple was inserted into the center of the sample and the other end was connected to a temperature recorder. Bath temperatures of C., 115 C., and 120 C. were used and the test periods were varied from 24 hours to 96 hours.

Inthe Mackay test the sample temperature gradually rises to bath temperature over a period of about 6 hours. Thereafter, ifrthe sample is reactive (i. e. unstable toward spontaneous heating), its temperature will continue to rise gradually a few degrees above bath temperature and then its temperature will `suddenly begin to rise rapidly, indieating that a vigorous exothermic reaction is taking place. If the sample is non-reactive (i. e. stable toward spontaneous heating), its temperature will remain at or only slightly above bath temperature.

The Mackay test is an'accelerated test, designed to determine in a few hours what may be expected to occur during several days or Weeks under practical storage conditions. `In the Mackay test the sample is subjected to much more severe conditions than would be encountered in storage. Accordingly, whereas a mass of dried lloating soap in storage may gradually rise toa temperature sufllciently high to damage the soap, a sample of the same material in the Mackay test will exhibit a sudden sharp rise in temperature after a few hours exposure. In both cases, the soap particles are fused into a charred, useless mass. i

Table 1 below gives the data and test conditions resulting from applying the Mackay test to floating soap made by adding various inhibitors thereto and then drying same (Example l above). Among other data, Table l shows the reaction temperature or temperature at which the sample began to react (column 5), the time which had elapsed under the test conditions when the reaction started (column 8), the maximum temperature the sample reached (column 6), the time which had elapsed when the sample` reached its maximum temperature (column 9), and crossover or Athe time which had elapsed when the sample Vreached the bath temperature (column 7). The same headings as used in columns 4-9 of Table l are used, respectively, as headings for the last six columns of Table 2 below. Table 3 below gives data under the same headings as Tables l and 2 except columns 5 and 8 of Table lV were not needed in Table 3 because none of the latter samples reacted or heated spontaneously. ln the samples which exhibited the sudden temperature rise characteristic of the unstable material, the particles of the floating soap fused into a single lump, whereas the sam-- ples which did not react in this way remained free owing after the test was completed.

The Mackay tests made on the samples of Tables 2 and 3 were supplemented by large scale tests in which 50 pound bags of tloating soap inhibited with sodium thiosulfate were stored in large stacks and observed over periods of thirty days `or more without witnessing any damage to the product due to spontaneous heating.

7 automatic recorder when testing samples 14 and 18 of Table 2 and sample 8 of Table 3. These are shown as the dotted line curve, the dash line curve and the solid line curve, respectively, in the drawing.

EXAMPLE 4 A solution comprising 400 parts sodium hydroxide and 19,00 parts water was prepared and heated to boiling. While the mixture was beingwell-agitated, 3200 parts of crude tall oil was slowly added, after which the soap was maintained at 100 C. for one hour while continuing to agitate. This produced a soft brown soap with an average solids content of about 65%. It had a pH of 10.5 when dissolved in water, and hence it did not contain excess alkali or tall oil. A measured amount of this tall oil soap was run into a mixing tank, the desired quantity of inhibitor was added thereto and the resulting mixture was agitated until uniformly blended. The blended wet mixture was` fed between two Vrevolving drums whose surfaces were maintained at a temperature of about 135 C.150 C. The mixture was then dried to a moisture content of about 5% (usually being 1%- 5%) and then doctored oft" the drums in the form of very thin, hot, sticky, flulfy and discontinuous films. The films were coo-led and broken up into a coarse or granular powder in suitable form for bagging and commercial use. This product had a bulk density of about 15 pounds per cubic foot.

8 oil soaps of the invention in the manner described in Example 3 above. However, in these tests a single bath having a temperature of 120 C. was employed and the test periods were 36 hours.

Table 4 below gives the data and test conditions resulting from applying the Mackay test to tall oil soap made by adding sodium thiosulfate as an inhibitor thereto and then drying same (Example 4 above). Among other data, Table 4 shows the reaction temperature or temperature at which the sample began to react (column fil), the time which had elapsed under the test conditions when the reaction Started (column 7), the maximum temperature the sample reached (column 5),the time which had elapsed when the sample reached its maximum temperature (column 8), and crossover or the time which had elapsed when the sample reached the bath temperature (column 6').

It should be noted in Table 4 below that sample 1 is conventional unpressed tall oil soap containing no inhibitor, sample 2 is conventional unpressed tall oil soap containing Na2S2O3 as an inhibitor, samples 3 and 4 are tall oil soap roll-pressed and made into flakes and are without and with the beneiit of Na2S2O3 inhibitor, respectively. Sample l exhibited the sudden temperature rise characteristic of conventional unstable tall oil soap and the particles thereof fused into a single lump, whereas samples 2, 3 and 4 did not react in this way and remained free-flowing after the tests were completed.

TABLE Lits-ADDING NarSzOa T0 TALL OIL SOAP-EFFECT ON SPONTANEOUS HEATING Temperature C. Hours to Beach Percent Sample N0. NanSzOa Bath Reac- Maximum Cross- Reac- Maximum tion over tion 1. Unpressed 0 120 150 173 5.6 25. 1 25. 6 2. Unpressed 3 120 None 124 6.2 Nono 36.0 3. Pressed.-- 0 120 None 126 5.2 None 36.0 4. Pressed--. 3 120 None 122 5.6 None 33. 5

EXAMPLE 5 It will be apparent from Table 4 above that we have Portions of the dried tall oil soap-inhibitor mixture ready for bagging from Example 4 above were obtained and further processed as follows. i

This tall oil soap mixture was pressed into sheets of roughly 1,46" thickness by passing same between two opposing 8" diameter steel pressure rolls. The surfaces of the rolls were maintained at a temperature of about 40 C. Then the sheets were broken up into relatively small akes all of which passed a screen having 57s" openings. This gave a compressed tall oil soap mixture having a bulk density of about 32 pounds per cubic foot and an absolute density of approximately 0.95 gram per cubic centimeter.

One roll was rotated by conventional driving means at a speed of about 4 R. P. M. The opposing roll idled and was rotated merely by the friction imparted by the driven roll through the tall oil soap mixture being pressed, the idling roll rotating at a speed slightly less than that of the driven roll.

In order to determine the comparative elect on spontaneous heating obtained by adding inhibitors to tall oil soap in accordance with Example 4 above and by the dual treatment of adding inhibitors to tall oil soap and pressing the resulting mixture in accordance with Example 5 above, the products of Example 4 and the products of Example 5 were evaluated by the Mackay test in the manner disclosed in Example 6 below.

EXAMPLE 6 Spontaneous heating tests Spontaneous heating tests were conducted on the tall obtained a very substantial improvement in stability against spontaneous heating by adding Na2S2O3 to conventional unpressed tall oil soap (sample 2), and that we have obtained a still greater reduction in spontaneous heating by the dual treatment (sample 4) of adding Na2S2O3 to conventional tall oil soap and pressing the resulting mixture.

The original data for Example 6 were obtained on a conventional circular recorder chart as continuous lines which were drawn by the automatic recorder connected to thermocouples in the samples under test, as mentioned in the first part of Example 6 above. The data in Table 4 above were obtained by reading olf values at appropriate points on the original recorder charts. Fig. 2 of the drawing accompanying this application is a graphical representation of the curves drawn by the automatic recorder when testing samples 1-4 of Table 4. These are shown as the dotted line curve, the X line Curve, the dash line curve, and the solid line curve, respectively, in the drawing.

EXAMPLE 7 The tests recorded in Table l of Example 3 were repeated with the sodium tallate contemplated by the pre..- ent invention. As in the case of oating soap, all of as limiting the scope of the invention as generically described.

Conditions for practicing this invention in accordance with the preferred embodiments disclosed and/or exempliiied above may be varied widely without departing from the spirit and scope of this invention. Instead of sodium thiosulfate, it is apparent that any of the other alkali metal thiosulfates and ammonium thiosulfates may be employed. This follows from the well-known chemical equivalence of the alkali metal thiosulfates. All of these compounds are substantially equally effective for the purposes of the invention. However, use of sodium thiosulfate is preferred because of its lower cost andv greater availability.

The quantity of inhibitor employed is not critical, but it may vary over a broad range. The amount of inhibitor -employed depends on a number of factors, two of which are the length of time and the degree of stabilization desired. If the soap does not heat spontaneously when subjected to the Mackay test, it is considered adequately stabilized for all practical purposes. It has been found that from 1% to 3% by weight, on the dry basis of the floating soap or tall oil soap, produces satisfactory results and incorporation of from about 2% to about 3% by weight is preferred. Although additional thiosulfate may be employed, it appears that there is little to be gained by addition of increased amounts. For example, tests made with 5% sodium thiosulfate exhibited no noticeable improvement over those made with 3% sodium thiosulfate. While the use of less than about 1% inhibitor reduces spontaneous heating and the use of quantities below 1% are within the scope of this invention, the reduction in spontaneous heating at this lower concentration is not as great as that desired for most industrial purposes.

Since the mechanisms involved in the stabilization effected by the present invention are unknown, it is not possible to explain why the thiosulfates contemplated by the invention are excellent inhibitors for spontaneous heating of oating soaps and tall oil soaps, whereas the many other materials which have been employed successfully by the prior art to inhibit oxidation of compositions such as resins, plastics, toilet soaps, and the like, are of no value as inhibitors Iof spontaneous heating in iloating soap and tall oil soap. One possible reason for the unexpected behavior of the inhibitors of the invention is that tall oil soap and floating soap are so different from other materials that they are in a class by themselves as compared with the compositions treated by prior art methods. Possibly the inhibitors of the present invention do not, as such, do the inhibiting but instead become associated with or combine with one or more of the varied constituents comprising the very complex mixture in the floating soap or the tall oil soap and the material thereby formed effects the stabilization. This hypothesis is offered merely as a possible explanation of the unusual results obtained by this invention and it is not intended as any limitation of the scope of the invention as disclosed and claimed.

Since it is apparent that widely different embodiments of this invention may be practiced without departing from the spirit and scope thereof, it is to be understood that the invention is limited only by the scope Iof the appended claims.

This application is a continuation-in-part of copending applications Serial No. 495,519, tiled March 21, 1955, now abandoned, and Serial No. 554,682, tiled December 22, 1955, now abandoned.

What is claimed is:

1. A soap product inhibited against spontaneous heating consisting essentially of a material Selected from the group consisting of tloating soap and tall oil soap obtained by concentration of black liquor resulting from 10 pulpwood digestion processes and containing at least a substantial portion of the impurities naturally present therein, and, as the sole essential inhibitor, an inhibiting amount of a material selected from the group consisting of alkali metal and ammonium salts of thiosulfuric acid.

2. The process for producing a soap product inhibited against spontaneous heating which consists essentially `of blending with a material selected from the group consisting of floating soap and tall oil soap obtained by concentration of black liquor resulting from pulpwood digestion processes and containing a substantial porti-on -of the impurities naturally present therein, as the sole essential inhibitor, an inhibiting amount of a material selected from the group consisting of the alkali metal and ammonium salts of thiosulfuric acid.

3. The floating soap 4of claim 1 wherein said inhibitor is sodium thiosulfate.

4. The floating soap of claim 1 wherein said inhibitor is potassium thiosulfate.

5. The floating soap of claim l wherein said inhibitor iS ammonium thiosulfate.

6. A substantially dry, compressed soap product inhibited against spontaneous heating consisting essentially of a material selected from the group consisting of floating soap and tall oil soap obtained by concentration of black liquor resulting from pulpwood digestion processes and containing at least a substantial portion of the impurities naturally present therein and containing, as a sole essential inhibitor against spontaneous heating, an inhibiting amount of a material selected from the group consisting of the alkali metal'and ammonium salts of thiosulfuric acid, said soap having an absolute density of at least about 0.95 g./cc.

7. The floating soap of claim 6 wherein said inhibitor is sodium thiosulfate.

8- The oating soap of claim 6 wherein said inhibitor is potassium thiosulfate.

9. The iioating soap of claim 6 wherein the inhibitor is ammonium thiosulfate.

10. The process for producing a substantially dry soap product inhibited against spontaneous heating which consists essentially of blending with a material selected from the group consisting of oating soap and tall oil soap obtained by concentration of black liquor resulting from pulpwood digestion processes and containing at least a substantial portion of the impurities naturally present therein and while said soap is in a particulate moist condition, as the sole essential inhibitor, an inhibiting amount of a material selected from the group consisting of the alkali metal and ammonium salts of thiosulfuric acid, and drying the resulting blend.

11. The pro-cess of claim 2 wherein said inhibitor is sodium thiosulfate.

12. The process of claim 2 wherein said inhibitor is potassium thiosulfate.

13. The process 4of claim 2 wherein said inhibitor is ammonium thiosulfate.

14. The process for preparing a soap product inhibited against spontaneous'heating which consists essentially of blending with a material selected from the group consisting of floating soap and tall oil soap produced by concentration of black liquor resulting from pulpwood digestion processes, as the sole essential inhibitor, an inhibiting amount of a material selected from the group consisting of the alkali metal and ammonium salts of thiosulfuric acid, and drying and compressing the resulting blend to an absolute density of at least about 0.95 g./cc.

. References Cited in the iile of this patent UNITED STATES PATENTS 2,128,083 Ellis Aug. 23, 1938 2,202,103 Hitchcock et al May 28, 1940 2,717,838 Barthel et al. Sept. 13, 1955

Claims (1)

1. A SOAP PRODUCT INHIBITED AGAINST SPONTANEOUS HEATING CONSISTING ESSENTIALLY OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF FLOATING SOAP AND TALL OIL SOAP OBTAINED BY CONCENTRATION OF BLACK LIQUOR RESULTING FROM PULPWOOD DIGESTION PROCESSES AND CONTAINING AT LEAST A SUBSTANTIAL PORTION OF THE IMPURITIES NATURALLY PRESENT THEREIN, AND, AS THE SOLE ESSENTIAL INHIBITOR, AN INHIBITING AMOUNT OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL AND AMMONIUM SALTS OF THIOSULFURIC ACID.

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