US 2772967 A
Description (OCR text may contain errors)
amounts of fatty acid yield reaction products which are of negligible value as sizing agents for paper. At the other extreme, the amount of fatty acid should not exceed the stoichiometrical equivalent Vof the hydroxyl groups as when a larger amount is used the products are unduly diflicult to disperse in water and therefore are not practical for papermaking purposes, and in practice the convenient maximum from the point of view of dispersibility is about ylo'of this value, particularly in the case of tertiary amines. Thus, in the case of a dialkanolamine such as diethanolamine the maximum amount of fatty acid is best limited to about 1.8-2.0 mols and in the case of a trialkanolamine such as triethanolamine to about 2.7' mols.
The results improve as the ratio of fatty acid to the amine hydroxyl groups is increased over the minimum value of 0.33 mentioned above. A sharp improvement results when the amount of fatty acid is 50% of the stoichiometric equivalent of the hydroxyl groups of the alkanolamine, and a plateau is reached when the amount of fatty acid is between about 2/5 and 5%; of the stoichiometric equivalent. Thus, in the case of diethanolamine best results are obtained by the use of between 1.3 and 1.7 mols of fatty acid per mol of the amine, and in the case of triethanolamine between 2.0 and 2.5 mols.
As alkanolamines there may be employed in the practice of the present invention any of the water-soluble short-chain secondary and tertiary alkanolamines, that is, alkanolamines having no chain longer than 6 carbon atoms. Suitable secondary amines include diethanolamine diisopropanolamine, 3,3iminobis1propanol, 4,4'- iminobis-l-butanol, and 6,6iminobislhexanol. Suitable tertiary amines include such N-alkyl dialkanolamines as N-ethyl-diethanolamine, N-propyl-dipropanolamine, and N-methyl-diisopropylamine and trialkanolamines such as triethanolamine, tributanolamine, triisobutanolamine, and trihexanolamine.Y The monoalkanolamines yield poor sizingrresults and these are 4therefore not included within the scope of the present invention. The alkyl or alkanol chains may be of the same or different length and may be branched; moreover, the hydroxyl groups may be primary as in the case of diethanolamine, secondary as in the case of diisopropylamine, or tertiary as in the case of the iminobis-t-butanol; We have found, however, that' the reaction of fatty acids with primary hydroxyl groups is more rapid than with secondary or tertiary hydroxyl' p sizing effectiveness.
groups and therefore the former type of compound is preferred.
As fatty acids there may be employed straight'chain' saturated acids such as hexadecanoic acid and octadecanoic acid and similar but branched acids obtained by petroleum oxidation. 'It is only necessary for the acid to have a sufficiently long carbon chain to render the ester composition as a whole suiciently hydrophobic for papermaking purposes, and the invention is not limited to the particular acids mentioned. Unsaturated fatty acids are undesirable but are tolerated in minor amounts. YNeither the particular alkanolamine nor the particular fatty acid is therefore a primary feature of the present invention.
While the fatty acids are preferred, nevertheless esters such as ethyl stearate and acid chlorides such as stearoyl chloride may be used. After reaction similar ester compositions are obtained and correspond to those obtained by the use of free fatty acid, the use of the acid chlorides however rendering subsequent additionof a solubilizing acid unnecessary.
It will be understood thatthe reaction products describedV above are generally complex mixtures. In the first place, the invention permits Vemployment of mixed amines and mixed long chain fatty acids, which of itself leads tormixed products. Moreover, fatty acid or fatty acid equivalent reacts according to a. normal distribution curve so that on the-'assumption that only esteritication occurs, the productis a mixture of mono and diesters,
in limitation thereof.
where dialkanolamines are employed, and are mono, di and triesters where trialkanolamines are employed. Since not all of the fatty acid need react by way of esteriiication or amidation, the product may contain a variable amount of the fatty acid salt of the alkanolamine ester. Further, there is evidence that Where secondary amines are employed some amide formation may take place resulting in the presence of alkanolamides or alkanolamide esters. As a result, the products are most conveniently described in terms of their preparation. Y
Where fatty acids or fatty acid esters are employed as raw materials for the reaction, the reaction products are converted before use to water-dispersible condition by addition of a mineral or organic, water-soluble, nonoxidizing acid having a dissociation constant not materially less than that of acetic acid. Suitable acids include hydrochloric acid, hydrobromic acid, nitric acid, formic acid, phosphoric acid, acetic acid, the chloracetic acids, propionic acid, and glycolic acid. Alternatively, materials such as Aepichlorohydrin and dimethylsulfate and alkyl halides such as ethyl chloride may be used which form acid or acid equivalent during their reaction with theester composition. In practice we prefer to use acetic acid or hydrochloric acid, these acids being readily available, non-toxic, and having the particularly desirable property of forming salts of desirably low softening point so that the step of dispersing the salts in water may be performed without need ofV autoclave equipment. 'I'he acid is advantageously stirred into the ester composition while in molten condition and atleast suiiicicnt is added to'render the composition dispersible upon agitation with 'hot water. Alternatively, the reaction product in molten form may be slowly poured into rapidly agitated hot water, that is, water having a temperature above the softening point of the reaction product. In the case of acetic acid we addfroin 1 to 2 mols per nitrogen atom of the alkanolamine and preferably about 1% to 11/2 mols, too little acetic acid causing the sizing results to fall olf. In the case of hydrochloric acid only between about 1A and 3/4 mols is necessary and addition of about 1/3 of a mol produces a composition of about the best An excess does not inactivate the size. Where fatty acid chlorides are employed, generally no acid Vneed be separately added.
The acids are best added in concentrated form so as to minimize the lamount of water introduced, thereby minimizinghydrolysis of the esters. Y
The process of the present invention does not preclude the addition of the materials customarily added in the course of paper manufacture. Included among these are melaminealdehyde, urea-aldehyde and other cationic resins to improve wet strength, starch, gums, and partially hydrolyzed polyacrylamides to improve dry strength, and pigments and dyes.
The invention will be more particularly described by the examples which'follow. The examples illustrate embodiments 'of the invention and are'not to be construed Example 1 The following illustrates the preparation of various sizes according to the present invention. Y;
The. sizes were prepared by charging technical stearic acid and the indicated alkanolamine into a three-necked ask fitted with a mechanical stirrer, nitrogen inlet tube, and thermo-meter. In each instance l mol of the alkanolamine was taken, and the number of mols of stearic acid is shown Vin the table below. The reactionimixtures were fheated to 200 C. in 45-60 minutes and maintained at that temperature at least until the `acid number dropped to 15, and generally below 10. Terminal acid numbers `areshown in the table. During the reactions, nitrogen gas was passed through the flask to minimize discoloration cand to `'sweep out the water formed. Y
i The products were Vcooled to about C. and vsalt- 4 Orming material stirred in as shown in the table below.
The ester salts thus formed were dispersed by slowly pouring the products into rapidly agitated water at 95 C. so as to form dispersions containing 5% solids, which were homogenized hot and then cooled. Details of the method by which the sizes were prepared are shown in the following table.
Fatty Acid Added Size No. Amine 1 Acid F. A. Hours Acid Mols 2 Ratio 3 Reacted No.
Name Mols 4 2. 5 0. 83 5. 25 6. 9 HC1 0. 35 2. 0. 67 4. 25 2. 2 HCl 0. 35 1. 0. 50 1. 25 5. 9 HC1 0. 25 1. 5 0. 50 1. 25 5. 9 HAC 5 1. 0 1. 5 0. 50 1. 25 5. 9 Me2SO4 0. 5 2.0 1.0 1.5 1. 5 HC1 0.25 1.5 0.75 1.5 2.5 HAU 5 1.0 1. 0 0. 50 l. 0 l. 1 HAC 5 1. 0 2. 0 0. 67 7. 5 13.7 HC1 0.5
1 D EA =diethauolamine; TEA =triethanolamine; TIPA =triisopro panolamine.
2 Per mol of amine.
8 Mols fatty acid divided by number of hydroxyl groups of amine.
Per mol of amine taken.
HAc =acetic acid.
Example 2 The sizes of Example 1 were diluted to 1.5% solids by addition of water and were evaluated as follows.
A 60% :40% bleached sulte-soda pulp mixture beaten to a Green freeness of 350 ml. was diluted to a consistency of 0.6% and adjusted to a pH of 4.5. Aliquots were withdrawn and treated with the materials shown in the table, the pH after addition of the material or materials being adjusted to the value shown by the addition of NaOH or HCl as required. Tlhe aliquots were gently stirred for ve minutes to allow adsorption of the size to take place, after which sheets were formed on a Nash handsheet machine, dried for one minute at 240 E., conditioned at 73 F., and 50% relative humidity for at least 24 hours, and tested for their water and ink resistance by the Currier and BKY methods respectively.
Percent Pulp Sheet Currier, BKY, Alum pH3 Basis See. Sec. No.1 Percent Added:l Wt! Added2 8. 5 Nil 4. 5 43. 4 66 600 8. 5 Nil 4. 5 43. 4 64 600 3. 5 Nil 4. 5 44. 1 29 353 5.0 Nl] 4. 5 47. 4 140 600 5.0 Nil 9. 0 44. 9 79 600 5. 0 Nil 4. 5 46. 8 67 600 5. 0 Nil 9. 0 46. 5 90 600 3. 5 Nil 4. 5 43. 4 54 600 5. 0 N11 4. 5 44. 0 130 600 5. 0 3. 0 4. 5 45. 7 145 600 5. 0 3.0 9. 0 44. 6 67 600 2. 0 Nil 4. 5 45. 1 35 0 3. 5 N11 4. 5 45. 5 61 600 1 Corresponds to sizes of table of Example 1. Based on dry weight oi the bers.
3 After addition of size.
4 Lb. per 25" x 40"/500 ream.
The results indicate that an effective |amount of sizing takes place both when the fibers are formed into paper at alkaline as well as acid pH values. The results with size No. 7 show that the addition of |a small amount of alum enhances the sizing effect obtained.
Example 3 The following illustrates a preferred method for manufacturing two typical .sizes of the present invention.
Size A.-1 mol of diethanolamine was reacted with 1.5 mols of technical stea-ric acid and neutralized with 1.25 mols of glacial acetic acid according to Example 1. The molten ester salt was cooled and crushed to about 10 mesh, and soaked for 6 hours in suflicient cold water to provide a slurry having `a solids content of 7%. The 'slurry was rapidly heated to 95 C. with rapid agitation. The slurry was cooled with continued agitation to room temperature and diluted to 5% solids by addition of water.
Size B.-This size was prepared by reacting l mol of triethanolamine with 2.5 mols of technical stearic acid, followed by the addition of 0.35 mol of 37% aqueous HC1, according to the method for the preparation of Size A.
The product was dispersed in water at 95 C. according to the method employed for the preparation of Size A.
When tested, both sizes gave somewhat superior results compared to the corresponding sizes of Example l.
1. Paper composed of cellulosic fibers sized by a uniformly adsorbent content within the range of about 1% to 4%, based on the weight of the libers, of a product corresponding to that formed by heating 1 mol of an amine selected from the group consisting of the lower water-soluble dialkanolamines, the lower water-soluble trialkanolamines and mixtures thereof with a saturated monocarboxylic fatty acid of 16-20 carbon atoms, the molar equivalence ratio of said fatty acid to the hydroxyl groups of said alkanolamine being between about 0.33 and 1.0, at an esterication temperature up to about 225 C. until reaction of said fatty acid with said alkanolamine is at least about 50% complete.
2. Paper according to claim 1 wherein the weight of the size is between about 2% and 344% of the Weight of the fibers.
3. Paper according to claim 1 having an alkaline pH.
4. Paper composed of cellulosic fibers sized by a uniformly distributed content within the range of about 2% to 31/z%, based on the weight of the iibers, of a product corresponding to that formed by heating l mol of a dialkanolamine with about 1.3 to 1.8 mols of a saturated monocarboxylic fatty acid of 16-20 carbon atoms a-t an esterication temperature up to about 225 C. until reaction of the fatty acid is at least complete.
5. Paper according to claim 4 wherein the dialkanolamine and the fatty acid are heated until reaction of the fatty acid is more than complete.
6. Paper according to claim 4 wherein the dialkanolamine is diethanolamine and the fatty acid is stearic acid.
7. Paper composed of cellulosic fibers sized by a uniformly distributed content within the range of about 2% to 3%% based on the weight of the fibers of a product formed by heating 1 mol of a trialkanolamine with about 2.0 to 2.5 mols of a saturated fatty acid of 16-20 carbon atoms at an estercation temperature up to about 225 C. until reaction of the fatty acid is at least 75% complete.
8. Paper according to claim 7, wherein the trialkanolamine and the fatty acid are heated until reaction of the fatty acid is more than 90% complete.
9. Paper according to claim 7, wherein the trialkanolamine is triethanolamine and the fatty acid is stearic acid.
10. Paper according to claim 7, wherein the trialkanolamine is triisopropanolamine and the fatty acid is stearic acid.
References Cited in the file of this patent UNITED STATES PATENTS 2,332,226 Hutchins Oct. 19, 1943 2,492,702 Neubert et al Dec. 27, 1949 2,668,111 Lindquist Feb. 2, 1954 2,683,088 Reynolds July 6, 1954 2,710,285 Trusler June 7, 1955 OTHER REFERENCES Industrial & Engineering Chem., January 1941, pages 17 and 21. (Copy in Scientific Library.)