US2128482A - Method of preparing a size - Google Patents

Description

Aug. 30, 1938. i w H. HARDING METHOD OF PREPARING A SIZE Filed June 25, 1955 02y POS/A/ ATTORNEY.

Patented Aug. so, 1938 2,128,482

UNITED STATES PATENT OFFICE METHOD OF PREPARING A SIZE William Harry Harding, Rockville Centre, N. Y., assignor to American Cyanamid & Chemical Corporation, New York, N. Y., a corporation of Delaware Application June 25, 1935, Serial No. 28,259

Claims. (01. 134-21) This invention relates to the manufacture of a darkened 1100 makes a size containing it useful composition of matter useful as asizing material only with certain types of paper or board and is and constitutes an improvement upon the invennot, therefore, universally useful. It is difi'icult tion disclosed in co-pending application of John to state the limits of this detrimental tempera- 5 F. Fredriksson, Serial No. 571,990, filed October ture, but it has been shown that a slightly ele- 5 30, 1931 now Patent 2,050,996. vated temperature maintained for a long time is In that application, it was proposed to dissolve equally as bad as a high temperature reached caustic alkali in water as a saturated or superfor only a comparatively short period. saturated solution, dissipate the heat of solution It has been discovered that if a solution of and then mix the same with powdered rosin to caustic is made of a concentration such that its 10 produce a partially reacted mass as a direct dry solids will not salt out at, say, 80 F. that more product. beneficial results are obtainable than has been As an alternative procedure to the above, that possible heretofore. A solution of less than satuapplication discloses the mixing of dry caustic ration at that temperature is more easily sprayed alkali, water and rosin to accomplish the same upon the ground rosin, making the necessity for 1d eflect. a large nozzle orifice unnecessary, it is possible to Experience has demonstrated that if the caustic use lower temperatures without getting into the alkali, such as caustic soda is dissolved in water 1100 darkening range, and less accumulated heat to make a saturated or supersaturated solution, must be dissipated. Of course, if a solution of a that such solution will salt out a part of the causconcentration less than saturated is used, it tic at temperatures lower than 95 F. When rosin means that for a given quantity of water, less is ground prior to treatment with the caustic alkali than is required to saponify an equivalent solution, it has been found desirable to refrigerportion of rosin must be used. Where a comate the same during the grinding period as this pletely saponified rosin product is eventually defacilitates the grinding action. This refrigeration sirable, it is proposed to add an additional quan- 25 temperature is usually in the neighborhood of 60 tity of alkali in solid form and preferably ground F. and the rosin is delivered from the grinding to 80 mesh. equipment to the mixing equipment at substan- With the above objects in View, therefore, the tially this refrigerated temperature. Under these invention, in one of its aspects, contemplates the circumstances, when the caustic solution meets use of a caustic alkali solution as a saponifying the cold rosin, there is an appreciable precipitaagent in concentrations which will not salt out tion of solid caustic from the solution. This preat the normal room or operating temperatures cipitated material is of comparatively large size commonly existent, to wit: in the neighborhood and, hence, causes an uneven distribution of the of 80 F. This concentration is short of saturaalkali through the rosin with which it is being tion and the caustic alkali contained in such solu- 35 mixed. This produces difliculties all along the tion may be likewise short of an amount required line. When a caustic solution at 95 is sprayed to completely saponify the amount of rosin used. upon the ground or crushed rosin, the added heat The additional quantity of a ka sa y for of the solution must be dissipated, together with saponification, where desired, may be added to the exothermic heat of reaction with the rosin the rosin in the solid state, preferably pulverized 40 and this, therefore, presents another objectionto, say, 80 m of Course, refrigeration ay b able feature of the above procedure. It is one resorted to to facilitate the crushing or grinding of the principal objects of the invention to overof both the rosin and the dry caustic alkali to be come the above objections. added thereto, although this is not necessary.

Such salting out action can be prevented by The invention further consists in the novel 45 maintaining the solution at a temperature elevatdetails more fully hereinafter described. ed enough to maintain the caustic in solution The drawing is a flow sheet illustrating a metheven when it has been'cooled by admixture with 0d employed. the relatively cold rosin but this is undesirable be- In practice and to produce an ultimately comcause it means that more heat must be dissipated pletely sapon fied m t 14 p n f C ustic 50 to prevent detrimental heat effects. It is well soda are required to completely saponify 100 known, of course, that if during the preparation pounds of rosin. In order to use only that quanof a'resinate, high temperatures have been used, tity of water in the reaction to produce a solid the fioc resulting from the subsequent addition of product without going through the liquid stage,

5E3 alum to the resinate emulsion is darkened. This this caustic is ordinarily dissolved in 12 pounds of water. As has been above stated, however, this quantity of alkali in the stated quantity of water gives a solution so saturated that it becomes supersaturated and salts out below 95 F.

In view of the above, it is preferred to dissolve less than 14 pounds of caustic alkali, say 12 pounds, in the equivalent of 12 pounds of water. This gives a solution so far from saturation as will avoid this objectionable salting out at F., yet making it possible to use this desirable comparatively low temperature. The remaining two pounds of alkali, where a completely saponified produced is desired, may then be added dry and preferably in a pulverized state of the fineness of 80 mesh to the powdered rosin. The alkali solution is either added to a mixture of powdered rosin and powdered dry alkali or the dry alkali may be added subsequently.

These proportions of solution alkali and dry alkali may be varied, of course, dependent upon the temperature at which the mixing is to take place, that is, the lower the'temperature used, the less concentrated should be the alkali solution and, where an ultimately completely saponified product is desired, the greater the quantity of the alkali added in the dry or solid state. Ordinarily, from 50% to of the alkali should be added in solution form. I

' When the above operations are followed, the alkali solution, the solid dry alkali and the rosin are thoroughly mixed, care being taken to avoid an undue rise in temperature. This may be accomplished by adding the solution, from which its heat of solution has been dissipated, slowly as by spraying so as to permit the heat of reaction to be dissipated or a positive cooling effect may be obtained in the mixing apparatus by providing cooling elements. Ordinarily, the lat-.

ter is not required. I

As a result of the above operations, a direct dry product is obtained which microscopically has been found to consist of particles of solid caustic alkali and particles of solid rosin, coated either individually or collectively with dry sodium res inate. This coating prevents the absorption of moisture by the dry alkali and consequent further reaction.

This dry product may be shipped in light waterproof bags to the consumer and have been found to be remarkably stable and free flowing even under adverse conditions of humidity and pressure. The customer desiring to make a rosin size emulsion has only to add a quantity of this material to a desired quantity of water and upon agitation the coating of resinate dissolves, thus liberating the dry rosin and caustic, which further react to produce a completely saponified emulsion which is useful as a size for paper or the like.

In this application, where the word caustic alkali is used, it is to be understood as covering caustic soda, caustic potash, ammonium hydroxide, or in fact any material which will saponify rosin in appreciable quantities without the aid of heat. This qualification necessarily eliminates soda ash as a saponifying agent for a considerable amount of heat is required if this form of alkali is used and as has been above stated, at

some length, heat is detrimental not only from the standpoint of cost because it requires additional equipment and a longer time element is involved, but also from the standpoint of a darkened floc.

I claim:

1. A method of preparing a dry composition of matter which includes mixing solid rosin, solid alkali and a solution of alkali the quantity of solid alkali used being greater than that which will dissolve in the solution of alkali at the mixing temperature, there being insuflicient water to give a liquid product-in which the total alkali used is sufficient to saponify the rosin, the dry alkali constituting from 10 to 50% of the total.

2. A method of preparing adry composition of matter which includes mixing solid rosin, solid alkali and a solution of alkali the quantity of solid alkaliused being greater than that which will dissolve in the solution of alkali at the mixing temperature, there being insufficient water to give a liquid product in which the total alkali used is sufficient to saponify the rosin, and of which from 90 to 50% is added in solution.

3. A method of preparing a dry composition of matter which includes mixing, solid rosin, solid alkali and a solution of alkali the quantity of solid alkali used being greater than that which will dissolve in the solution of alkali at the mixing temperature, there being insufficient water to give a liquid product in which the dry and dissolved alkali is the same. r

4. A method of preparing a dry composition of matter which consists in separately grinding rosin and caustic soda to substantially 80 mesh, dissolving 12 pounds of caustic soda in 12 pounds of water, maintaining said solution at substantially 80 F., mixing pounds of the ground rosin with two pounds of the ground caustic and spraying the caustic solution onto the mixture while agitating and While preventing any substantial rise in temperature.

5. The method of claim 4 in which the rosin is cooled to 60 F. during the grinding operation.

WILLIAM H. HARDING.

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