US2306652A - Process for refining wood rosin - Google Patents

Description

Patented Dec. 2 9, 1942 PROCESS FOR REFINING WOOD ROSIN William N. Traylor, Hattiesburg, Miss, assignor to Hercules Powder Company, Wilmington, Del., a corporation oi Delaware No Drawing.

Application April 10, 1940,

Serial No. 328,867

12 Claims.

This invention relates to a process for refining rosin and more particularly relates to a process for refining wood rosin.

It is well known that wood rosin obtained by extraction of pine wood, for example with a suitable solvent, is dark in color due to the presence of color bodies. Many methods have been proposed in the art for the removal of color bodies from the rosin to produce rosins of paler grades. These methods, however, have been open to one objection or another. Thus, while some methods have given a certain degree of refinement, they have not always been successful in producing a rosin of the degree of refinement required for many uses. Furthermore, in those processes where light-colored products have been made, it has been necessary to subject the rosin to treatments which generally result in a low yield of the refined rosin, and, consequently, a relatively high cost per unit.

It is an object of this invention to provide an improved process for refining wood -rosin.

It is a further object to provide an improved process for refining wood rosin which is extremely simple and economical.

It is another object to provide a process for refining wood rosin in which ordinary plant equipment may be used.

It is still another object to provide a process for refining wood rosin in which the properties, other than color, of the refined rosin are substantially unaltered from those of the unrefined original rosin.

It is a still further object to provide a process for refining wood rosin which will provide a refined product in a substantially quantitative yield based on the original rosin.

Other objects of the invention will appear hereinafter.

The above objects are accomplished in accordance with this invention by treating wood rosin under ionizing conditions with an acid salt and a metal above hydrogen in the electromotive series. The treatment is carried out under conditions which will provide intimate contact between the rosin, the acid salt and the metal. As a result of the above treatment the color of the rosin becomes substantially lightened with practically no loss in yield and no perceptible efiect on the other physical properties.

In accordance with the process of this invention the treatment may be carried out on the rosin in the molten condition or it may be carried out on the rosin dissolved in a suitable organic solvent. After the treatment of the rosin is completed, the rosin or the rosin solution may I be washed to remove the water-soluble materials and filtered to remove the metal.

- been subjected to a previous refining process,

such as are well known in the art, may be used. If a very pale rosin is desired, a wood rosin which has already undergone a refining-treatment will be preferred. Relatively pale rosins may be produced, however, from wood rosins as dark as FF lOSln.

As solvents for the rosin, where the treatment is carried out on the rosin in solution, any solvent for rosin which is itself inert in the treatment may be employed. Among such solvents are, for

example, monocyclic aromatic hydrocarbons, such as benzol, toluol, xylol, etc.; petroleum hydrocarbons, such as gasoline, V. M. and P. naphtha, hexane, heptane, etc.; hydrogenated petroleum hydrocarbons, such as those known in the trade as "Solvesso solvents; and solvents such as ethylene dichloride, carbon tetrachloride, cyclohexane, methylcyclohexane, etc. Where the treatment is carried out on the rosin in solution the concentration of the rosin in the solvent is not critical and may be selected so as to provide adequate workability of the solution. Generally speaking, a concentration within the range of about 5% to about 95% by weight may be used, but preferably the concentration will fall within the range of about 20% to about 50% by weight.

The acid salts which may be used in the process of this invention are those which contain one or more replaceable hydrogen atoms, such as, for example, sodium acid sulfate, potassium acid sulfate, monosodium acidrphosphate, disodium acid phosphate, monopotassium acid phosphate, dipotassium acid phosphate, calcium acid phosphate, lithium acid phosphate, etc.

Any of the metals above hydrogen in the electromotive series may be employed. It will be preferable, however, to use such metals which form salts having no appreciable discoloring action on rosin. The metals are used preferably, though not necessarily, in a finely divided form. Use of metals, as, for example, cadmium, aluminum, manganese, tin and zinc is very desirable. Zinc in the form of zinc dust, mossy zinc or zinc powder is particularly well adapted to the process.

Having described the improved process of refining rosin in accordance with this invention in broad terms, a more detailed description of the process will now be given. As stated above, the treatmentmay be carried out on the rosin in molten condition or dissolved in a solvent. In either case, it is desirable that at least a small amount of water or of some other ionizing solvent be present to accelerate the refining action. Thus the acid salt may be used in the form of a hydrate,.if it forms one, or in the form of an aqueous solution. Sodium acid sulfate in the form of its monohydrate is particularly desirable. Alternatively, a small amount of water or other ionizing solvent may be added. An aqueous solution containing from about per cent of the acid salt to a saturated solution of the salt at the temperature employed may be used.

It will be understood that the acid salt and the metal above hydrogen in the electromotive series are both in contact with the rosin during the treatment. To provide satisfactory contact of the ac d salt and metal with the rosin it will be desirable to employ vigorous agitation since the refining action will be appreciably accelerated.

The speed with which the rosin becomes refined in accordance with the process of the invention is dependent on the temperature employed in the treatment. While the treatment may be carried out at room temperature with ros n d ssolved in a solvent, the rate of refining is rather slow for p actical purposes. It is preferable to carry out the treatment at elevated temperatures and temperatures as high as 160 C. have been found to be satisfactory. A temperature within the range of about 70 C. to about 125 C. has been found particularly satisfactory. When carrying out the treatment on the rosin in solution it is convenient to operate at the reflux temperature of the solution. Where the treatment is to be carried out above the normal boiling point of the solvent, use of superatmospheric pressure is resorted to. The pressures employed are in no way limiting on the process and the equ pment employed will generally determine the maximum pressure which is practical.

The time of treatment of the rosin in accordance with the process of the invention may be varied to provide the result desired. The time necessary to provide satisfactory refining of the rosin will be dependent on such factors as the amount of color bodies present in the rosin, the

temperature of treatment, the amount of acid salt employed, as well as others. For this reason it is impossible to state any definite time necessary, except in relation to a given set of conditions. serve to illustrate the time of treatment which may be used in each particular case.

The amount of acid salt used may vary over a wide range, depending upon such factors as the particular acid salt used, the degree of refining desired, the particular conditions of treatment, as well as other factors. Considering the acid salt on an anhydrous basis, for example, ratios of wood rosin to acid salt as high as to 1 on a weight basis have been used. In general, however, ratios varying between 10 of rosin to 1 of acid salt down to 1 of rosin to 1 or more of acid The examples which follow will.

salt are desirable. A preferred ratio is approximately 1 of acid salt to 2 of wood rosin.

The amount of metal above hydrogen in the electromotive series used is not particularly critical. It will be desirable, however, to have an amount of such metal present which will be an excess over the theoretical amount required to react with the acid salt present.

As illustrative of the improved process of refining wood rosin in accordance with this invention the examples appearing below are cited as typical of the various embodiments. The colors shown in the examples are the Lovibond glass colors measured on cubes of the rosins.

Example 1 Two hundred parts by weight of a 50% solution of K wood rosin, (40 Amber+1.5 Red) in benzol were refiuxed for one hour at a temperature of TO-73 C. with 30 parts by weight of sodium acid sulfate monohydrate (NaSCrHzO) and 20 parts by weight of zinc dust. The solution was then filtered, diluted to a 20% rosin concentration with fresh benzol, washed three times with water, filtered, and the rosin-containing solution heated to distill off the benzol, the last of the solvent being removed while sparging with carbon dioxide. The color of the refined rosin was 11 Amber, corresponding to a grade of X. The yield was substantially quantitative.

Example 2 Five hundred parts by weight of a 20% solution of K wood rosin (40 Amber+1.5 Red) in gasoline were heated in a Monel metal autoclave with 250 parts by weight of a 30% a"ueous solution of sodium acid sulfate and 50 parts by weight of zinc dust. The contents of the autoclave were heated to a temperature of 158 C. with agitation, the pressure rising to 70 lbs/sq. inch. After allowing the autoclave to cool, the rosin-containing solution was removed and washed with water several times, filtered, and the solution then heated to distill off the gasoline, the last of the gasoline being removed while sparging with carbon dioxide. The color of the refined rosin was 22 Amber, which corresponds to a WG grade. The yield was substantially equal to the rosin treated.

Example 3 Grade U. 8. standard tim Lovibond color Original FF rosin F Refined rosin M Example 4 Three thousand parts by weight of a 25% solution of FF wood rosin in benzol, 1000 parts by weight of a 35%aqueous solution of sodium acid sulfate and parts by weight of zinc dust were heated together under vigorous agitation in an Grade Lovibond g fi; color 8rd type Original FF rosin 80A+3OR. F Reflnedrosin 40A+2.5R. K

Example Two hundred parts by weight of a 50% solution of FF wood rosin in benzol were refluxed for 25 minutes with 20 parts by weight of zinc dust and 20 parts by weight of sodium acid sulfate monohydrate. Thereafter '300 parts by weight of benzol were added and the diluted benzol solution was washed with a 5% aqueous oxalic acid solution and then with distilled water. The solution was filtered, the volatile components distilled oil', the last thereof being removed while sparging with carbon dioxide. The yield of refined rosin was 98.5% based on the weight of the FF rosin used. The improvement in color was as follows:

(ljrage Lovibond standcolor Md type Original FF rosin 80A+20R G Refined rosin 38A M Example 6 Fifty parts by weight of M wood rosin were dissolved in 200 parts by weight of gasoline. This solution was refluxed with 30 parts by weight of sodium acid sulfate monohydrate and 20 parts by weight of zinc dust for one hour.-

The refined rosin solution after cooling was then washed three times with water, filtered to remove the metal remaining and the rosin then recovered by distilling off the solvent, the final portions thereof being removed while sparging with carbon dioxide.- The refined rosin was obtained in a yield of 98% based on the weight of M rosin A 50% benzol solution of a crude wood rosin .having a color of about 80 Amber+300 Red was prepared. Portions of 100 parts by weight each dioxide.

of this benzol solution were refluxed separately 7 for one hour each with the following acid salts and metals, the proportions being by weight.

acid sulfate monohydrate. 10 parts of aluminum and 10 parts of sodium acid sulfate monohydrate. 10 parts of zinc and 10 parts of sodium acid sulfate monohydrate. 10 parts of zinc and 10 parts of potassium acid sulfate. 10 parts of zinc and 10 parts of primary 4 sodium acid phosphate. 10 parts of zinc and 10 parts of primary calcium acid phosphate. 10 parts of tin and 10 parts of sodium acid sulfate monohydrate.

In each case the metal was present in divided form and in 4, 5 and 6 a small amount of water was included.

After treatment in each of the above cases the refined rosin solution was diluted with 150 parts by weight of fresh benzol and was given three water washes. Thereafter the solution was filtered, the volatile portions distilled off, the last thereof being removed while sparging with carbon in each case was as follows:

Sample number Lovibond color amber+300 red. 80 amber-H00 red. 80 amber+2l0 red. 80 amber+ 50 red. 80 arlglber+l50 red.

80 amher+l30 red. 80 amber-+210 red.

Example 8 acid sulfate monohydrate for one-half hour at a temperature of to C. Thereafter the reaction mixture was allowed to cool and the rosin extracted with parts by weight of toluol. The rosin solution was then filtered through a bed of Filter-cel in order to remove small amounts of dispersed zinc. The solvent was then removed under reduced pressure, the rosin remaining graded M+ in color, which constitutes-an improvement of 1 grades.

The process of refining wood rosin described in accordance with this invention may also be carried out as a continuous process. Thus, the rosin solution inay, for example, be treated with the acid salt and metal in a suitable vessel While the rosin solution is fed into the vessel continuously. The acid salt and metal may be replenished as necessary in the reaction vessel. A continuous flow of refined rosin solution may thus be pro ided from the reaction vessel.

The many advantages of my improved process of refining wood rosin will be readily apparent from the above description and examples. The process is extremely simple and economical. The color improvement of rosin obtained is remarkable, particularly in view of the high yield of refined rosin obtainable. In previous methods of improving the color of rosin a considerable loss in rosin has always been evident.

It is to be understood that the term "refining used throughout this invention refers particularly to the color improvement of the rosin and 10 parts of magnesium and 10 parts of sodium The color of the refined rosin obtained 7 not necessarily to a separation of the rosin into light-colored and dark-colored fractions.

It will also be understood that the details and examples hereinbefore set forth are illustrative only, and that the invention as broadly described and claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is:

1. A process for refining wood rosin which comprises treating wood rosin with an acid salt prises treating wood rosin in molten form with an acid salt and a metal above hydrogen in the electromotive series in the presence of at least a small amount of water.

4. A process for refining wood rosin which comprises heating wood rosin with an acid salt and a metal above hydrogen in the electromotive series in the presence of at least a small amount of water.

5. A process for refining wood rosin which comprises heating wood rosin with an acid salt and a metal above hydrogen in the electromotive series at a temperature not in excess of about 160 C. in the presence of at least a small amount of water.

6. A process for refining wood rosin which comprises treating wood rosin dissolved in a suitable solvent with an acid salt and zinc in the presence of at least a small amount of water.

'7. A process for refining wood rosin which comprises treating wood rosin dissolved in a suitable solvent with zinc and a hydrate of sodium acid sulfate in the presence of at least a small amount of water.

8. A process for refining wood rosin which comprises treating wood rosin dissolved in a suitable solvent with sodium acid sulfate monohydrate and zinc in the presence of at least a small amount of water.

9. A process for refining wood rosin which comprises treating wood rosin dissolved in a suitable solvent with zinc and an aqueous solution of sodium acid sulfate.

10. A process for refining wood rosin which comprises heating wood rosin with an acid salt and a metal above hydrogen in the electromotive series at a temperature within the range of about 70 C. to about 125 C. in the presence of at least a small amount of water.

11. A process for refining wood rosin which comprises heating wood rosin with sodium acid sulfate and zinc at a temperature within the range of about 70 C. to about 125 C. in the presence of at least a small amount of water.

12. A process for refining wood rosin which comprises heating wood rosin dissolved in a suitable solvent with sodium acid sulfate monohydrate and zinc at a temperature within the range of about 70 C. to about 125 C.

WILLIA N. TRAYLOR.