Composition of osin Si Precipitat EFFECT OF HEAT AND OXIDATION ON COMPOSITION DONNA PRICE' Hercules Experiment Station, Hercules Powder Company, Wilmington 99, D e l . A
Analyses of rosin size precipitates prepared at 25" and 60' C. showed a small difference in composition. explainable in terms of contamination of the precipitate made a L the higher temperature with inorganic substances present a t the time of i t s formation. inalyses of rosin size pre-
R
OSIN size does not impart water resistance t o paper if the treatment is carried out under conditions which subject the wet size precipitate to heat over an appreciable time (3, I O ) . Holvever, except for a statement by Keugebauer (4)that ternperature has no effect on the size precipitate' ash, there is no information concerning the effect of heat on size precipitat.e composit.ion. PREPARTION AYVU AXALYSES
cipitates prepared at 25" C . and of the same precipitates after aging for two arid a half years at room temperature showed that the composition had changed in the following manner: an increase of 8 to 9% in oxygen, a decrease of 1 to 29" in carbon, and a decrease of 0.5q0 in hydrogen.
perature for several hours, gave CIA1 values about 10% louer than that of the control. In view of the unsatisfactory precision of the check analyses on the control ( 8 % difference in C/XI), the difference between precipitate 1 and precipitates 2 and 4 cannot be established as significant. However, check analyses on the other four precipitates were more satisfactory (0 t o 3.5% difference in the C/Al value of replicate sample^). Therefore, the difference between precipitates 2 and 4 and precipitate 3 (comparable to the control) does seem significant. For this reason i t is believed that size precipitate heated t o 60" C. for a sufficient time showed a small composition change.
Precipitates I Y ~ I ' C made at 25" arid 60" C. and the conipositioris compared. The clieniicals and experimental procedure used were described in the first paper of this series (8). As before, t,he OCCURRENCE OF HYDROLYSIS term "alum" denotes papermakers' alum, essentially X12(SOa)3.18H20. The only variation in the procedure for preparing standThis change in composition is,not believed to be due t o hyardized size precipitates is in the use of the higher temperature drolysis. Since the products of the hydrolysis of size precipitate and result,ant cooling intervals for some of the preparations. (aluminum hydroxide and resin acids) are insoluble, the actual Table I describes the size precipitates and gives their analyses. weight of carbon and aluminum in any sample of size precipitate Precipitates 1, 3, and 5 were indistinguishable by t,he ratios of car(and hence the C/Al value) will remain the same whether or riot bon to aluminum (C/A1). However, after 10-minute healing a t hydrolysis occurs. 60" C., both the color of precipitate 5 and the pEI of its suspenHydrolysis will, on the other hand, decrease the percentage of sion changed, an indication of some physicochemical change from both carbon and ash. For example, a dry, unoxidized precipitate the form of control precipitate 1. The control material was consisting of 50% resin acids plus neutral materials and 50y0 aluminum diresinate has the theoretical composition 77.0% prepared by the standardized procedure ( 8 ) . The decrease of p H wit,h heat is typical of aluminum salt solutions, and the color change is also shown by aluminum hydroxide. TABLE I. EFFECT OF HEATO N ROSIXSIZE PRECIPITATE C O U P O S I T I O S It is not surprising that precipitate pH of .Ish A1 1 and precipitate 3 (dilute size einulPrecipi@t+Suspension C, (1200' C . ) , (Calcd.), Ratio. NO. Preparationa Appearance a t 2 5 O C. To 7% yo CIA1 sion heated a t 60" C. for 10 minutes, 1 Control, a t 25' C. Light metallic 4.50 75.3 4.45 but cooled to 25" C. before addition 7 5 . 1_ _4 . _ 10 gray _ of alum) are practically identical. Mild .Iv. 75 2 4 , 28 2 27 33.1 heating should not be expected to affect 2 .It,6O0 C.. cooled t o 25O White 3.80 74.6 4.60 74.4 4.76 in 2 hr. a dilute size emulsion in any irreversi__ __ dv. 74.5 4.68 2.48 30.0 ble manner. Therefore, the results indi3 Rosin size added a t 60° Light metallic 4.50 75,O 4,31 cate that the advcrse effect is due 7 4 . 8 4 . 3 1 C.; s o h . cooled in 10 gray min. to 25' before pptn. to heating the size precipitate, and A v . 74.9 4.31 2.28 32.8 that the size alone may be heated with4 At 60° C., filtered hot White 3.85 74.1 4.70 (filtration time, about 73.9 4.86 out detrimental effect, providcd the 2 hr.) Av. m 4.78 2.53 29.2 4.30 75.2 4.37 systom is cooled prior t'o addition of 5 At 6.0" C . , cooled in 10 White 0 alum. min. t o 25' -7 5 . _ _4 . 3 5 PreciDitates 2 and 4, prepared a t AI,, 7 5 . 1 4.36 2.31 32.5 T o 1 liter of water, 25 ml. of 3 . 0 7 size A were a PrecipiLates prepared from size A (20% free rosin). 60" C.-and maintained a t that temThe amount of alum added
-
7--
,Present
address. 202
29th
st,, Balti-
added in each case. 5.66-5.75 ml. of 5.0% alum were subsequently added. to the materials prkpared a t 60° C. was t h a t required by t h e control (5.66 ml.) for a final pH of 4.5.
more 11, iMd.
1274
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1949
1275
observations were confirmed in the present work. When precipitation was 0 by carried out a t 60' C., curdiness was Ashb A1 Differ- Total apparent a s soon as alum was added. Ch, Hb, (1200° C.j, (Calcd.), Ratio, encec, 0, Sample NO.^ 7 5 % % % C/A1 % % The floc settled rapidly, and the super6 76.4 9.62 4.00 2.12 36.0 10.0 11.8 natant liquor contained fine particles i ( r o m g o s i t e o f equalamounts 76.0 9.50 4.19 34.4 in stable suspension. (The stable sus34.8 of 3 separate prepn.) 7 6 . 4 10.12 4.14 76.0 9.68 4.14 34.6 pension was obtained with 10-minute Av. 7 6 . 1 9.77 4.16 2.20 34.6 10.0 11.9 stirring of size precipitate at 60" C.; 152.16 68.7 &i (compositeof equal amounts 7 8 . 3 10.20 minute stirring resulted in a clear super2.12 69.7 oi 2 separate prepn.) 78.4 9.79 Av. 7 8 . 4 1 0 . 0 0 2.14 1.13 69.2 Y..i 10.5 natant liquor.) On the other hand, the a Sixe A used i n each case. control precipitate prepared at 25" C. b Values are a v e r a ~ e sof two determinations. showed no curdiness but the usual volu0 100 (% C % I1 + % ash). d A mixture of 30% HISO, and 70% alum (10% solute) w a s used in place Of loo% foi preminous, slow-settling floc and clear superciriitation b y the standard procedure. natant liquor. Moreover, the same behavior is observed on mechanical redispersion of the settled floc. These observations suggest t h a t a t 60" C. many small nuclei carbon, 3.94% ash, and C/Al 36.8. The same material, after of precipitate are formed and that most of them collide to form hydrolysis t o resin acids and aluminum hydroxide [assumed to larger particles. Thus, a mixture held at 60" C. for 10 minutes be AI(O€I)3] has the composition 74.870 carbon, 3.79% ash, and contains some very small particles in stable suspension, although C/Al 36.8. Table I shows a small decrease in carbon content accompanied b y a distinct increase in ash. T h e five precipitates the bulk of the floc seems permanently coagulated. If the same mixture is stirred at 60" C. for 15 minutes or longer, the precipiof Table I were prepared on the same day b y the standard protate is in the form of permanent aggregates of more than one cedure. It is assumed, therefore, t h a t their moisture content micron in diameter and, consequently, ineffective in sizing. were about the same and, hence, t h a t the changes noted in carbon At 25" C. the nuclei have much lower kinetic energies, and their and ash values are significant. Since the percentage of carbon collisions may result in the formation of loose, easily redispersed decreased while the percentage of ash increased, the change canagglomerates. I n contrast t o the chemical examination, therenot be attributed t o hydrolysis although some hydrolysis may fore, physical examination of size precipitates a t 25' and 60" C. have occurred. The most likely explanation of these changes and of the resultant lowering of the C/AI value is that the ash suggests a factor, the degree of agglomeration of the precipitate particles, which may well affect the efficiency of the precipitate increased because t h e precipitate carried down Al( 0H)t formed as a sizing agent. by the hydrolysis of Alz(S04)3 at 60" C. The addition of only 0.8yo AI(0H)a t o the standard precipitate is sufficient t o account EFFECT O F AIR OXIDATION for the maximum observed lowering of the C/Al value and t o reduce the carbon content from 75.2 t o 74.6%. Work on the autoxidation of rosin and resin acids has been T h e second paper of this series ( 7 ) mentioned t h a t no satiscarried out chiefly in France and Russia. 4 recent paper by t h e Pavlyuchenkos (6) reports results consistent with those of factory method of moisture determination has been found for mrlier workers but somewhat more specific. They found t h a t these materials, b u t that the moisture content was, after standard desiccation, about 1%. Precipitates 1, 3, and possibly 5 would one mole of abietic acid absorbed one mole of oxygen, and showed 5 corresponding weight increase Ims the weight of a small quanbe expected t o have this moisture content; the equal values found for carbon and ash indicate a n identical water content. If tity of volatile products. The chief oxidation product was a precipitates 2 and 4 had a differentmoisture content, it would be peroxide, and the acid number of the oxidation product was the expected t o be lower because of their exposure to a higher temsame as t h a t of abietic acid. This indicated t h a t the main perature. With t h e loss of 1% water and with no chemical reaction was addition of oxygen a t one of the two double bonds change, the carbon value would be increased by 0.8% and in the acid molecule. However, a later Pavlyuchenko paper (6) the ash value by 0.05%. The actual changes are in the opposite suggests as reaction products both this peroxide and one formed direction for carbon and are much larger for ash. Hence, any by the addition of two moles of oxygen per mole of acid. difference in moisture content due t o the different temperatures of precipitate preparation will not, i n this case, have TABLE 111. -4XALYSES O F ROSINSIZE PRECIPITATES 2.5 YEARS AJ?"ER PREPARATION a significant effect'on the results. --Oxygen, yo-Besides acquiring some inorganic maAsh . AI Recent By C, H, (1200' C.1, (Calod.), Rstio. method differterial, the precipitate prepared at 60' C. Sample N o . % % % % C/A1 (1) ence Total may also have undergone some hydroly6, aged 70.5 8.64 3.83 17.3 sis. But, because of the observed 70.3 8.74 3.75 17.4 A v . 70.4 8.69 3.79 2.01 35.0 17.4 17.1 19.1 changes in composition, little if any 7, aged 70.0 8.58 3.88 17.4 hydrolysis did occur. These analyses, 70.0 8.86 3.89 17.7 therefore, do not reveal any change in 4 v . 70.0 8.70 3.88 2.06 34.0 17.6 17.4 19.4 composition adequate to account for 9 , aged 71.6 8.84 1.97 ... the large change observed in sizing 71.6 8.77 2.00 17.9 -4v. 71.6 8.80 1.98 1.05 68.2 17.9 17.6 18.8 (3, IO). OF FRESHLY PREPARED RosiIi SIZEPRECIPITATES TABLE 11. ANALYSES
-
I
+
>
I
(CH8COO)zPHYSICAL FORM OF PRECIPITATES
There are many reports in the literature of the gelatinous nature of the size precipitate formed at 25" C. and of the less voluminous granular form obtained at higher temperatures. These
Al(OHj.xHz0
28.1 4.35 28.4 4.33 28.3= 4.34
29.97 29.91 29.9
15.8
1.79b
33.1 33.4 33.5 33.3a
..
..
Theoretical values for dry alurmnum diacetate are: 29.6 and 34 6 4 0 exclusive of oxygen required t o form A1208, If corrected t o the dry basis b y use of the values'fo;C,'it becomes 34.8% 0. If corrected t o the dry basis by use of moisture determination (distillation w t h toluene), it becomes Either corrected result is in good agreement with the theoretical. 35.04 b 'fieoretical, 1.78. 5
INDUSTRIAL AND ENGINEERING CHEMISTRY
1276
OF OXIDATION ON COMPOSITION OF ROSIN TABLEIV. EFFECT SIZEPRECIPITATES
Sample
Analysis,
%
KO. 6
7
C
H
1
2
Freshly Prepared Ppt.
P p t . after 2.5-Year Aging at Room Temp.
76.4 9.62 4.00
Ash 0 (diff.) Total c
10.0 100.0
Ash 0 (diff.) Total
0 100.0
H
76 9 4 10
1 77 16
70.4 8.69 3.70 17.1 100.0
io
0 8 70 3 88 17_ 4 _ 100 0
3
Col. 2 Cor. to Initial Ash Value 74.3 9.17
4.00
1 8_ .1 _ 105.6
75 0 9 33 4 16
18 7 -~ 107 2
TABLE v.
4
Change, C?1. 3 minus Col. 1 -2.1 -0.45
Sample NO. 1
2
3 4
0
i - i $5.6 -1 -0 0 +S f7
5
1
44
a b
7 2-
It was expected t,lia.t rosin size precipit,ate (resin acid and aluminum diresinate) and size (sodium resinate) would show oxidation behavior similar t o that found for abietic acid, although the metallic compounds and nonacid components of rosin may affect the rate of oxidation. T o investigat,e the change in size precipitate composition due to oxidation, samples were analyzed after two and a half years of st'orage. Table I1 gives analyses of the freshly prepared materials; Table I11 lists data on the same materials after storage at room temperahre. While samples %-ere stored in closed glass containers, sufficient oxygen was available for react,ion because of the extremely low bulk density of the precipitat,es. Analyses of Baker's C.P. basic aluminum acet,at,eare also presented in Table I11 for comparison. OXYGENANALYSIS. A recent, method ( 1 ) for deterinining oxygen in organic compounds was used in analyzing the aged size precipitates. However, for these metal organic compounds its use is still in the exploratory stage. The results of Table 111 show that the value for oxygen by this method ( 1 ) is the same as oxygen by difference-i.e., the oxygen in the compound in escess of that required t o form aluminum oside, not total oxygen. This result is reasonable because carbon would not be expected t.o reduce aluminum oxide. The chief effect of aging on the precipitate composition was an increase in oxygen content. Table IV shows that oxidation resulted in a gain of 8.1 t o 9.5 grams of oxygen per 100-gram sample, and was accompanied by a small loss of hydrogen (0.57.) and of carbon (1 t o 2%). The net gain in weight of the sample was, therefore, only 5 t o 8%. Treatment, of the standEFFECT OF HIGHER TEMPERATURES. ard precipitate at, higher temperatures had little or no effect on oxygen pickup. For example, a fresh sample held in an oxygen stream a t 70" C. for one week gaiiled 8.4% oxygen: another heated at, 100" C. in the preseiice of air for 6 weeks gained 9.17, (9). On t,he other hand, these tm-0 treatixents resulted in much higher losses of carbon and hydrogen than did aging alone (Table 1V)-3.4 and 0.9%, respectively, a t 70" C., and 7.3 and 1,7%, respectively, at 100" C. (9). Thus the increase in weight of the sample oxidized a t '70" C. was only 4%, and no change in weight occurred a t 100' C. Evidently heat, has lit.tle effect on the degree of oxidat,ion but a marked effect on the amount of volat,ile materials, such as wat,cr and carbon dioxide lost by the various compounds in the size precipitate. AKALYSISBY cLTRAVI0LET *kBSORPTIOX SP results are similar to those reported by the Pavlyuchenkos and arc in accord with the opinion t h a t oxidation products consist mainly of peroxides formed by addition of oxygen a t the double bonds of the resin acids: The destruction of the double bonds in the acids and sodium salts was strikingly shown by the change in ultraviolet absorption after oxidation. D a t a for this change are
Vol. 41, No. 6
AN.4LYSES O F OXIDIZED ROSINS AND SIZES BY ULTRA' VIOLET ABSORPTION SPECTRA
Total Abietic-Type Description Resin Acidsa, % K gum rosin (9Zy0 resin acids) 45 Resin acids from No. 1 48 No. 2 after 2.5-vear Rtoraze ?,Q .. Size €3 prepared"from No.'i with neutral materials removed b y petroleum ether extn. (S5yO removed); stored 2.8 years 21b No. 4 freshly prepared, heated in air a t 100° C . Sb for 6 weeks; stored 2.5 years
By acid isomerization f2). Results corrected for sodium content of size.
given in Table V. I t is not, surprising that resin acids (sample 3 ) showed less oxidation in tivo and a. half years than the corresponding size (sample 4). The resin acids were in lump form aiid offered far less surface for reaction than did the sizes, amorphous powders. Osidation was not complete: i.e., some sodiunl resinate remained, even in the material suhject.ed to the most extreme conditions (sample 5 ) . ST;MM ARY
Rosin size precipitates prepared at 25" (control) and a t 60" C. iyere analyzed for carbon and ash. The precipitate prepared a t 60" C. showed a slightly loiver carbon content and an appreciably higher ash content than the standard. These differences are esplained in terms of contamination of the higher-temperature precipitate by inorganic material. inconclusive as to the occurrence of hydro1 a t 60" C., they do show t,hat, if any hydro1 lit,tle. Samples of precipitates analyzed before and after 2.5-year storage a t room temperature showed a cornposition change consisting chiefly of oxygen pickup. While a gain of 8 to 97, oxygen was the major part of t8hechange, small losses of carbon and hvdrogen also occurred. Higher temperatures did not, affect the osygen gain but resulted in greater loss of carbon and hydrogen. Ultraviolet absorption curves of aged resin acids and sizes showed a decrease in abietic-type resin acids wit,h oxidation. A recent method for determining oxygen in organic compounds made it possible to analyze size prccipitat'es for ash, carbon, hydrogen, and oxygen exclusive of t,hat required for ash formation. If t h e met-hod had yielded total osygen. an ultimate analysis of the precipitates would have been possible. Since this was not possible, the method merely confirms the validity %€I % ash) for the total oxygen less of using 100 - (% C that amount necessary to combine with t,hr aluminum present for ash formation.
+
+
ACKNOWLEDGRIEXT
The writel wisher t o thank the prrsonnrl of Ilerculrs I h p r r i ment Station n-ho contributed to this investigation, in particular, V. A. Aluise who cariied out the oxygen determinations, and E. V. Cook who obtained the ultraviolet absorption data. LITERATURE C I T E D
-4luise, V. -1..Hall, R. T., Staats, F. C . , aiid Becker, IT.IT., A N . ~ L(:HEM.. . 19, 347-51 (19471, (2) Harik. G . C., and Sanderson, T. F . , J . Am. Chem. Soc., 70, (1)
334-9 (1948).
( 3 ) Harrison, H. A , , Proc. Tech. Sect. Paper M n k e r s A s s o c . G . B r i t . & I r e l a n d , 12,Pt. 1, 161-208 (1932). (4) Neugebauer, E. L., Papier-Fabr., 10, 1308-12 (1912). ( 5 ) Pavlyuchenko, >I. M., J . P h y s . Chem. (U.S.S.R.), 18, 283-93
(1944). (6) Pavlyuchenko. J f . M.,and Pa.ilyuchenko, K . V., Lesokhim. P r o m . , 3, No. 4,20-4 (1940). ( 7 ) Price, Donna, A n a l . Chem., 20, 444-9 (1945). (8) Price, Donna, IXD.ENG.C H E h I . , 39,1143-7 (1947). (0) Price, Donna, Paper Trade J . , 126, KO. 15, 61-6, Table V
(1948). (10) Tech. Assoc. Pulp Paper Ind., Special Rept. 1, 50-4 (1926). RECEIVED April 13, 1948.
