US2288476A - Size emulsion and method of preparing the same - Google Patents

Description

Patented June 30, 1942 UNITED STATES PATENT OF FICE y I 2,288,476

SIZE EMULSION AND METHOD OF PREPAR ING THE SAME Robert T. Mashburn, Parchment, Mich, assignor to Hercules Powder Company, Wilmington, Del., I a corporation of Delaware No Drawing. Application September 7, I Serial No. 293,797

'1 Claims. (01. 106 -144),

or suspended as free rosin. It has been established that, under certain conditions, the sizes having a high free rosin content impart better sizing than neutral or low free rosin sizes. This is due to the drastic action of hard water on neutral or low free rosin sizes, which causes rosin to floc or precipitate in dilute solution and fail to-properly'size the paper efficiently.

In order, to increase the free rosin content of sizes, it has been customary to add acidic materials, such as, boric acid, to rosinate solutions. A difliculty oi this procedure was that relatively large quantities of boric acid were requiredto free the rosin and that the addition of boric acid did not lower the pH value an appreciable extent. The addition of. such quantities of boric acid increased the cost of the size and the use of this size required a relatively large amount of alum to be added to the paper stock,'which further increased the cost of sizing. Another objection is that, a relatively large quantity of protein stabilizing agent was used. Also, the electrolite materials remaining in the stock were objectionable in some cases. l I

Thepresent invention aims to overcome the above difliculties by providing an improved, stable, high free rosin size emulsion and methods of. producing the same.

"An object of the invention emulsion or dispersion having a relatively high free rosin content.

Another object is to provide a rosin emulsion which can be utilized more economically.

Another object is to provide a rosin emulsion A further object is to provide a method of preparing and stabilizing high free rosin content emulsions.

Other and further objectswillbe obviousupon an understanding of the illustrativeembodiment about to bedescribed, or will be indicatedin the appended claims; and various advantages not 'referredto herein will occur to one skilled in the art upon employment of the invention in. practice. 1

.These objects, are accomplished by dispersing or emulsifying in water, substantially 'or completely saponified rosin sizes which normally providea dispersion or emulsion having a relatively lowiree. rosin content, that is, about 35% or less free rosin by titration methods, or about 45% or less by extraction methods. Astabilizing agent may be either added to the concentrated size or to the emulsions, and after thorough mixing an acidic gas is passed through the mixture while continuing agitation, whereby the mixture converted into a high free rosin emulsion. This emulsion may be added .to the beater be'ater chest, to the Jordan engine, the head box, or any is to provide a rosin other suitable location.

In accordance with the invention, I have found that any grades of gumor wood rosins or the like, saponified to produce sizes having a low vfree rosin-content, can be advantageously converted to a high free rosin emulsion. In practice, I may employ any water-soluble alkali metal rosinate, such as a paste size, a dry size, or' a cold saponified size. The stabilizing agents I found to be suitable are, for example, caseinjsoya bean protein, animal glue, or other known protective colloids which are readily available on the market.

The acidific gases which are suitableyare of I 'the class which when passed through water dis- 40 solve and unite with the water to iorm acids. Such gases, for example, are carbon dioxide (CO2) sulphur dioxide ((SOa) acetic acid fumes,

which is not afiected adversely by variations in the hardness of the water and condition of the paper pulp.

Another object is to provide high free rosin emulsion which can be prepared by treating low and chlorine or hydrochloric acid .gas.- Iiprefer the use of carbon dioxide because it is relatively inexpensive and is available in flue gas-which is "ordinarily wasted; does not endanger the-health of the operators; does not corrode-the paper plant equipment; and does not react unfavorably withv compounds in the rosin or with the casein. As a source of carbon dioxide, I may use compressed carbon dioxide gas supplied in cylinders or dry ice (solid carbon dioxide). Sulphur dioxide-may also be used, but because of its verting rosin emulsions having low vfree rosin content into stable emulsions or dispersions hav-- ing a high free rosin content.

chemical activeness and its ability to form a relatively stronger acid more caution is necessary to prevent local coagulation. Acetic acid fumes, chlorine or hydrochloric acid gas, when diluted with air or relatively inert gases produce the desired acidification and freeing of the rosin.

In carrying out the invention, I add to a suit- The mixture may contain betweenabout 1 and 20% solids, but usually a concentration between 5 and is used. To thismixture, if so desired, I may add a colloidal stabilizer vsuch'as casein, soya bean protein, or animalglue. tween about-l and colloid based on the solid rosin content-of the mixture may be used:

the actual amount used depending on and being determined by specific paper mill conditions. 7

These colloids maybein alkaline solutions previously ,,prepared by adding about'l0% co loid to weighed at intervals to determine the weight of"- gas added;

The emulsionprepared by the above procedure was then diluted rome /z solids, first by-using I water No. 1, having a hardness of 20 grains per gallon (calculated as calcium and magnesium) and then by using water No. 2, having a hardness of 15 grains per gallon. As presented in the following table, tests were made on emulsions taken at various times when increasing amounts of carbon dioxide'had been added to determine per cent'carbondioxide, total solids, free rosin; pH

Properties of alkali rosinate (alkali abietate) size water containing, for example, 7% of sodium carbonateor other weal; alkali which facilitates dissolving or emulsifying the colloid. If'desired, the dissolved colloids may be added to the paste size or to the dilutedsize solution before or after being treated. with the ac'idific gas. colloid'may be ground and mixed with dry alkali adapted to' be added to the'paste ort'o the dilu-- tion thereof. Also the colloid may be mixed in dry form as apowder'or other physical state with dry size which subsequently is dissolved.

H I then pass aci-dific gas or acid fumes through the mixture, either with or without mechanical agitationof the mixture. The gas dissolves in the water to form an acid which will ionize to give hydrogen ions adapted to react with the al kalir'osinate (alkali a"ietate) to give free rosin (abieticacid) suspended in finelydivided, minute particles. .When sufficient gas has throughfthe mixture, the original translucent appearance of the mixture, which characterizes a low free rosin emulsion. gradually changes to an opaque, and in some instances where a light colored resin is used, to a milkwhite'appearance characteristic ,of a high free rosin emulsion;

In other words, the soluble or emulsifiable rosin soap, characterized by a clear mixture or solution was thrown out of solution by the acidific gasinto aninsoluble state to form a free rosin -dispersion containing between and free 3 rosin by extraction The resulting dispersion may. then be used as a paper size'in any usual manner.

EXAMPLE I .A quantity of 144 pounds 01" commercial rosin i paste size, mostly sodium rosinate, containing 7.0% totalsolids and 13.1% free rosin by titraticn, was heated in a size heating and measuring lsettle tol65 F. A quantity of 20.2 pounds solution of 20% casein which had been cut with 4% sodium' carbonate based on the weight of casein was stirred into'the size and heated therewith for .1 5 minutes. The resulting cascin-rosinsizewas diluted at 168" with water at 166 F. to give 16% solids rosin emulsion containing about 4% casein based on solids in the emulsion.- Cold water was used forthe dilution of the 16% emulsion to 6%: I i

Carbon dioxide was then passed from a cylinder into the emulsion whil'e at through per- -forated spray heads'placed adjacent the bottom of the tank and the emulsion was agitated. Carbon dioxide was added at'the rate of about 5 pounds per hour forthirty minutes and then at a rate of about .3 pounds per hcur,a nd at a net pressure of, 12.5 pounds per square inch. While adding the carbon dioxide, the cylinder was Also, the

passed value and stability.

contamzng 4% cascm, after treatment unth carbon dioxide gas.

I Emulsion, Stabilityu on U i dilutionin 10..- Sam- Addition Pet ple time 01' cent pH I No. C01 C02 Total Free added solid rosin ex- No. 1 No. 2 traction Mfinates Percent ,Percent 'The samples of the size were also examined microscopically and it was found in all casesfthat between 95 and 99% of the particles ,ofthe size did not exceed-one micron and in each instance no particles greater than three microns were found. This indicated that the size contained finely divided and minute particles' which could be readily dispersed or emulsified; Also, a very stable emulsion is provided by these particles which requires a small amount of stabilizingcolloid. The tests also indicated that the size emulsionsremained stable for more than 44 hours whendiluted with hardwaters to a concentration of about .G'75%. This stability isadequate to accomplish a satisfactory degree of sizing by virtue of the fact that it by far exceeds the maximum time pulp is in process in a paper mill.

A batch sizing emulsion corresponding to sample E was added to apatch of paper pulp in a beater and it was found that a smaller quantity of alum than usually required was necessary to give good sizing results. This is due to the fact that the size has a relatively low pH (as compared with sizes employed heretofore) and less adding between 10 and 12% carbon lcw free rosin size solution.

additionalmaterials are, therefore, required to lower thepI-L- d From the foregoing table, it will be observed that high free rosin size emulsions can be economically prepared. For 'example, a size emulsion having between. 78and 81% free rosin and a pH between 7.5 and 8.5 can be prepared by dioxide' to a I EXAMPLE II A quantity of .rosin paste size calculated to contain pounds of size on a dry basis was heated to a temperature of about to F.

water t-o contai n 8% solids and 6 pounds of casein in 14% solution, and cut with 6% sodium "carbonate (based on. weight of casein) was added and stirred in for 1-5 minutes.

. While continuing agitation 18 pounds of solid' carbon dioxide f dry ice) was added in small pieces over a period of an hour and a half, the rate of addition being slower at first.

Five batches were prepared in this manner. The final pH varied between 8.5 and 8.6 and the solids, on a dry basis, between 6.66 and 7.15%. A sample of each batch was examined microscopically and it was found that 99% of the particles of the size did not exceed one micron and in no case particles greater than 3 microns were found. The size emulsion was diluted with hard water to 075% solids, and was found to be stable and non-fleecing.

By using dry ice as a source of carbon dioxide, the carbon dioxide can be handled, weighed and added to the emulsion very conveniently.

EXAMPLE III To 200 grams of water at 165 F. were added 30 grams of liquified size paste (70% solids) L which had about free rosin on a dry basis. To the mixture was added 10 grams of a 10% casein solution which was previously cut with 7% sodium carbonate. While thoroughly agitating the mixture, sulphur dioxide gas was passed therethrough for five minutes and caused to dissolve in theemulsion. A suitable size emulsion having a high free rosin content was provided.

From the foregoing description and examples, it will be seen that the present invention provides an improved high free rosin size which can be economically made and can be used more eiiiciently as a size emulsion. The emulsion is not affected adversely by variations in the hard ness of the water when diluted and does not flock at low concentration when diluted with relatively hard water. By using an acidific gas which can be driven from the paper pulp in the latter stages of the paper manufacture, a better paper is provided. Also, the acidific gas lowers the pH considerably without the use of large amounts, and further decreases the amount of materials such as alum required for sizing the pulp. The size emulsions prepared in accordance with the present invention remain stable for long periods without sacrificing any advantages thereof. A further feature is that carbon dioxide in the form of stack gas, which is ordinarily wasted, can be utilized.

It will 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:

l. The process which comprises passing an acidiiic gas into an aqueous dispersion comprising saponified rosin to partially decompose said saponified rosin and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing a high proportion of free rosin on the dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant.

2. The process which comprises passing gaseous carbon dioxide into an aqueous dispersion comprising saponified rosin to partially decompose said saponified rosin and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing a high proportion of free rosin on the dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant.

3. The process which comprises passing gaseous sulfur dioxide into an aqueous dispersion comprising saponified rosin to partially decompose said saponified rosin and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing a high proportion of free rosin on the dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant.

4. The process which comprises adding solid carbon dioxide to an aqueous dispersion comprising saponified rosin to partially decompose said saponified rosin and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing a. high proportion of free rosin on the dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant,

5. The process which comprises passing gaseous carbon dioxide into an aqueous dispersion comprising saponified rosin and a stabilizing colloid to partially decompose said saponified rosin and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing a high proportion of free rosin on the dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant.

6. The process which comprises passing gaseous carbon dioxide into an aqueous dispersion comprising sodium rosinate and casein and containing from about 1 to about 20% by weight of solids to partially decompose the sodium rosinate and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing between about and about by weight of free rosin on a. dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant.

7. The process which comprises passing gaseous carbon dioxide into an aqueous dispersion comprising saponified rosin and casein to partially decompose said saponified rosin and liberate free rosin of extremely fine particle size and in highly dispersed form, whereby there is formed an aqueous rosin sizing dispersion containing a high proportion of free rosin on the dry basis and being stable against flocking when diluted with hard water for a period of time greater than the normal time elapsed between adding the sizing dispersion to the paper pulp and the addition of a size precipitant.

' ROBERT I. MASHBURN.