Among those interested in the pulp and paper lines, who joined the Entente delegation from Ontario in visiting Montreal, Three Rivers and Quebec were W. P. Gundy, managing director of W. J. Gage and Co., and S. J. Moore, President of the F. N. Burt Co., Toronto.
SOME CHEMICAL AND PHYSICAL REACTIONS OF ROSIN SIZE SOLUTIONS
Paper read by J. A. DeCEW at the meeting of the American Chemical Society.
It is quite to be expected that in any class of chemical reactions which occur under such varying conditions as those existing during the precipitation of rosin size in paper mill practice, there will be among the various investigators a certain amount of disagreement regarding the theoretical explanation of what actually takes place. There is also some confusion resulting from the termology which is commonly used in describing sodium resinate compounds existing in rosin size, as for example, in the use of the phrase “free rosin”. The purpose of the following remarks is not to recapitulate the work of other investigators, nor to criticize their conclusions, but to submit a short discussion of the effect upon the chemical reactions involved, of the various physical conditions in which the material may be used.
It is a well known fact that a rosin soap will easily dissolve an equivalent amount of rosin to that which has been saponified, and this extra rosin, whether in solution in the size wax, or whether in suspension in a diluted solution, is still called “free rosin” in the termology of the trade. In order, however, to distinguish between the various states in which the rosin might exist, it should be divided into three classes, consisting first, of dissolved rosin, second, colloidal rosin, and third, rosin in suspension. The reason for this is that before the rosin soap can be used in the art of paper making it must first be brought into dilute aqueous solution.
If the soap should be readily soluble, then dilution may take place in cold water and consequently the diluting can be carried out within the beater itself. On the other hand, if the rosin soap is not readily soluble in cold water, owing to the fact that it contains a considerable quantity of dissolved rosin, it is necessary to bring it into a sufficiently dilute condition so that no further material separation of rosin will take place when it comes in contact with the paper stock. Obviously the difficulty of carrying out this operation increases in proportion with the amount of extra rosin which is held in solution in the rosin soap.
Authorities disagree as to whether abietic acid is mono-basic or dibasic and it cannot be stated definitely whether rosin which is in complete solution in a rosin soap is there in the form of an acid resinate, or whether it is merely dissolved rosin. It seems to the writer that a fairly intelligible conception is obtained by assuming that a sodium resinate containing rosin in solution, is in fact an acid resinate of the alkali metal and that from this solution insoluble acid resinates of the heavy metals can be produced.
Some interesting data on this subject is recorded by E. O. Ellingson in a paper before the American Chemical Society, 1914, the subject being “Abietic acid and some of its salts.” In this investigation he shows clearly that certain insoluble acid abietates were formed when a dilute aqueous solution of sodium abietate was added in small proportions to a dilute solution of a metallic salt.