CA1057467A

CA1057467A - Method of preparing aqueous dispersions of fortified rosin

Info

Publication number: CA1057467A
Application number: CA255,071A
Authority: CA
Inventors: Paul H. Aldrich
Original assignee: Hercules LLC
Current assignee: Hercules LLC
Priority date: 1976-06-17
Filing date: 1976-06-17
Publication date: 1979-07-03
Also published as: JPS52154858A; DE2727254A1; SE7707010L; MX4263E; NL7706613A; FR2355055B2; FR2355055A2; IT1081843B

Abstract

Abstract of the Disclosure Disclosed is method of preparing an essentially stable aqueous dispersion of from 25 to 50% or more rosin base material. The method involves homogenizing an unstable aqueous dispersion of rosin-base material, a relatively small amount of which is in the form of a soap, such as the sodium soap, of the rosin-base material, the soap serving as a dispersing agent for the unsaponified rosin-base material. The dispersions are useful in the sizing of paper.

Description

~057~7 -This inven~ion relates to a novel method of prsparing essentially stable aqueous dispersions of ros1n-base ~aterial in finely divided form.
The aqueous dispersions prepared in accordance with this invention have particular utility in the manufacture of sized paper, papermaker's alum ~aluminum sulfate) or a similar precipating agen~ being usually employed in conjunction therewi~h to assist in precipating the rosin-base material on the paper fibers. The dispersions of this invention can be used in internal sizing ~ -techniques and in external sizing techniques. In internal sizing, the dis- ;~
persion and alum are preferably added separately to an aqueous suspension of papermaking fibers at varlous stages prior to sheet formation, and, in exter-; nal sizing3 paper sheeting is first formed, and subsequently treated by known methods, with ~ho aqueous dispersion to provide sized paper. Aqueous disper-sions prepared in accordance with this invention can be used to prepare paper products, such as paper webs, having improved resistance to penetratîon by water and aqueous ink.
1~ In accordance with one aspect of this invention~ there is provided - ; a p~ocess for preparing an essentially stable aqueous dispersion of rosin-base material adapted for use in the sizing of cellulosic papermaking ibers which comprises homogenizing under a pressure of from about 2000 p.s.i.g. to about 8000 p~s~i.g. and at a temperature of from about 125 C to about 180 C
ji an unstable aqueous dispersion containing, by weight, at least about 25%
- solids, the solids consisting essentially of, by weight, from 0% to about .,.~
95% rosin and fr~m 100% to about 5% of an adduct reaction product of rosin and ~ an acidic compound containing the ~ =0 group, the amount of adducted acid-`"` ic compound being from about 1% to about 20~ o~ the total solids weight, and, i i~ n0cessary, removing from the dispersion any particles whose size is greater :i,:
`, than about one micron characterized in that the process is carried out in the `~ presence of an anionic dispersing agent.

: According to a further aspect of the invention thera is pro~ided ; ~ 30 an essentially stable aqueous dispersion o~ rosin-~ase material adapted for use :., ;: .
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, 57~7 in the sizing of cellulosic papermaking fibers whi h h~s been prepared by a process which comprises ho~ogenizing under a pressure of from about 2000 p.s.i.g. to about 8000 p~s.i.g. and at a temperature of from about 125C. ~o about 180C. an unstable aqueous dispersion containing, by weight, at least about 25% solids, the solids consisting essen~ially of, by weight, from 0%
to about 95% rosin and from 100% to about 5% of an adduct reaction product of rosin and an acidic compound containing the ~ O group, the amount of adducted acidic compound being f~om about 1% to about 20% o the total solids weight, and, if necessary, removing from the disp~rsion any particles whose size is greater than about one micron characterized in that the process is carried out in the presence of an anionic dispersing agent.
Anionic dispersing agents are known in the ar~. In carrying out this inven~ion the preferred anionic dispersing agent is a soapJ such as the sodium soap, of a rosin-base material such as the rosin-base material of which the dispersion is comprised. Other suitable anionic dispersing agents include synthetic emulsifiers such as the salts o~ alkylaryl sulfonic acidJ salts of condensed naphthalene sulfonic acidsJ salts of dialkyl esters of sulfosuccinic acid9 salts of alkyl half esters of sulfuric acid, and salts of alkylphenoxy (polyethyleneoxy) ethanol half esters of sul~uric acid.

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~S7467 In the case of the alkylaryl sulfonate the alkyl group may be linear or branched with ten to eighteen carbon atoms. Var-ious mixtures of these alkylaryl sulfonates may be used. The pre-ferred aryl group is phenyl. Sodium alkylbenzene sulfonates~which f~ are especially useful are available commercially under a variety I of trade names, including Ultrawet D.S. (Arco Chemical Company).
Condensed naphthalene sulfonic acid salts are also available under various trade names, including Tamol S.N. (Rohm & Haas Co.) and Stepantan A (Stepan Chemical Co.). ~;
` lO In the case of the salts of dialkyl esters of sulfosuc-cinic acids the alkyl groups will include cyclohexyl, hexyl, iso-i` butyl, octyl, pentyl and tridecyl. In the case of the salts of half alkyl esters of sulfuric acid, the alkyl group may have ten to eighteen carbon atoms. In the case of the salts of alkylphen-.. , . , : . .
, oxy(polyethyleneoxy)ethanol half esters of sulfuric acid, the ~ `

i preferred alkyl group is the nonyl group obtained in propylene 1 ~, trimerization. The polyoxyethylene content can average from one ~ ;

~-l to twenty moles per mole, but an average of four to twelve is ¦ preferred. Amount of synthetic emulsifier used will be 1-5% with 1.5% to 2.5% being preferred based on the rosin-base material.

~i When using synthetic emulsifiers other than the alkyl-, aryl sulfonates it is important not to hold the aqueous solution, ` 3 ~:-~ the unstable dispersion or the finished emulsion at a temperature j above 100C. for more than a few minutes since otherwise the emul-... :
.'.;3 sifier will be destroyed by hydrolysis. Therefore, use of a con-tinuous process of heating, emulsifying and rapid cooling is ' desirable.
The rosin-base materials employed will be, by weight, from 0% to about 95% rosin and from 100% to about 5% of an adduct reaction product of rosin and an acidic compound containing the -C=C,-,C=O group, the amount of adducted acidic compound being from . .
1% to about 20% of the total solids weight.
~j As above set forth, the preferred anionic dispersing - `
agent employed will be a soap or salt of the rosin-base material.

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Thus, in the preferred embodiment of this invention, a relatively small amount of the rosin-base material will be present as the soap or salt thereof to serve as the anionic dispersing agent.
While not required, other anionic dispersing agents can be in-cluded if desired. ~
Thus, there will be present either a small amount of ~ I
saponIfied rosin or a small amount of saponified rosin adduct or a small amount of both. The amount of saponified rosin-base mate-` rial present, represented as a percentage of available carboxyl `
groups saponified, will be from about 0.5% to about 20% and pref-, - . .
erabl~ from about 4% to about 10%. The preferred content of the ~
.~ .:
~ solids of the dispersion will be, by weight, from 0~ to about 85%

;~ rosin and from 100% to about 15~ rosin adduct, the amount of ad-, ducted acidic compound being from about 4% to about 8%, and the ;

il amount of saponified rosin-base material present, Pepresented as `~ a percentage of available carboxyl groups saponified, being from j about 4% to about 10%.
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A convenient way to prepare the unstable aqueous disper-sion is to mix together the desired amount of water; the desired 20 amount of rosin-base material; and an alkaline material, such as 1 sodium hydroxide, in an amount sufficient to form the desired `~
amount of saponified rosin-base material. I ~ ;
~ It is not necessary that the saponified rosin-base mate--~ rial be formsd in situ. It can, if desired, be prepared prior to the preparation of the unstable aqueous dispersion. Thus, for ex~

ample, an unstable aqueous dispersion can be prepared by mixing together the water, the rosin-base material, and a saponified rosin- ``
base material ~uch, ~or example, as the sodium salt o~i adducted rosin, in an amount sufficient to provide an unstable aqueous dis-`~ 30 persion containing the ingredients in the above amounts. This procedure will be used when other anionic dispersing agents are used. Thus, for example, prior to homogenization, an unstable aqueous dispersion is prepared by mixing together water, rosin-base material, and anionic dispersing agent.

:.: , -- D, _ ''1 ~ ~579L~7 After preparation of the unstable a~ueous dispersion, it ~ a3~ f~o~C
is heated to a temperature of from about ~ . to about ~g5~C~
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Agitation thereof during the time required to reach the required temperature is recommended. The heated dispersion is then sub-jected to extreme shear whereby there is provided an essentially stable aqueous dispersion. Extreme shear is conveniently accom-plished by means of an homogenizer. Thus passing, at least once, the heated mixture through an homogenizer under a pressure of the order of from about 2000 p.s.i.g. to about 8000 p.s.i.g. will pro-vide an essentially stable dispersion.
The aqueous emulsion is subsequently cooled to provide the novel dispersions of this invention. Cooling may be carried out using any normal means, but it is preferred that the emulsion be introduced into a quench loop and rapidly cooled. This loop consists of cooied emulsified product pumped through a heat ex-changer. The pressure of the loop is kept high enough to prevent flashing of the product.

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~ Some particles might form heavy agglomerates which can `1 eventually settle out of the dispersion after a period of time.
1 20 These can be easily removed, if desired, from the otherwise essen-tially stable dispersion by filtration, by decantation, or by other means known in the art.
The particles comprising the dispersed phase are rela-tively small and have a particle size of from about 0.01 micron to about 1 micron. At least about 90~i by weight of the suspended particles have a particle size of less than about 0.5 micron.
When rosin is employed as a part of the rosin-base mate~
rial, it can be any of the commercially available types of rosin such as wood rosin, gum rosin, tall oil rosin, and mixtures there- ;~
of, in their crude or refined state. Partially or substantially completely hydrogenated rosins and polymerized rosins, as well as . ~
rosins that have been treated -to inhibit crystallization, such as ;~
by heat treatment or reaction with formaldehyde, can be used, as well as mixtures thereof.

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The adduct reaction product of rosin and an acidic com~
pound containing the -C=C-C=O group is derived by reacting rosin and the acidic compound at elevated temperatures of from about 150C. to -210C~ Methods of preparing these adduct reaction ~ -products are disclosed and described in U.S. patents 2,628,918 and ,

2,684,300. These adduct reaction products are often referred to in the art as Diels-Alder reaction products. The adduct reaction products are hereinafter sometimes referred to as "rosin adducts", "adducts", and "fortified rosin".
Examples of acidic compounds containing the -C=C-C=O
group that can be used to prepare the adducts include the ~
unsaturated polybasic organic acids and their known anhydrides, specific examples of which include fumaric acid, maleic acid, acrylic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid and citraconic anhydride.
Rosin used to preapred the adduct can be any of the com-:. 1 mercially available types of rosin such as wood rosin, gum rosin, ~ tall oil rosin, and mixtures thereof in their crude or refined ;;~ state. Hydrogenated rosins can be used as well as rosins treated to inhibit crystallization. Also, it is possible to employ an adduct that has been substantially completely hydrogenated after adduct formation.
,! Suitable alkaline materials capable of forming a salt ~ with rosin and rosin adducts include the usual inorganic and or-`i ganic basic materials employed to form a saponified rosin or a saponified rosin adduct. Examples of such include lithium hydrox-ide, sodium hydroxide, potassium, hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, ammonia, and water-soluble amines such as morpholine, ethylamine, n-propylamine, and n-butyl-amine. Preferred alkaline materials are potassium hydroxide and sodium hydroxide.

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;ij As above set forth, salts or soaps derived by reaction of rosin or rosin adduct and an alkaline material can be used to .
prepare the unstable aqueous dispersion, as well as other anionic ,', .

~i74~7 dispersing agents, if desired. The sodium soap of adducted rosin is an example of such a salt or soap and can be prep~red by adding a hot aqueous solution of sodium hydroxide to fused adducted rosin and maintaining the temperature of the reaction mass at about 110C. until reaction is substantially complete.
The rosin-base materials of which the dispersion is com-prised can all be derived from the same rosin source or from dif-ferent rosin sources. Thus, for example, the rosin component can be a mixt~re of substantially completely hydrogenated wood rosin and unrefined wood rosin, adduct component can be an adduct of un-refined wood rosin and fumaric acid, and the saponified material which functions as dispersing agent can be the sodium salt of a fumaric adduct of gum rosin. As another example, the rosin com-ponent can be tall oil rosin, the adduct component can be the ;
` adduct of wood rosin and maleic anhydride, and the saponified mate~
;~ rial can be the potassium salt or soap of the maleic adduct of tall oil rosin. As still another example, the rosin component can be a mixture of partially hydrogenated wood rosin and tall oil rosin, the adduct component can be the adduct of partially hydro-'~ 20 genated wood rosin and fumaric acid, and the saponified material . -, .
`' can be the potassium salt of the adducted hydrogenated wood rosin.
Other and various combinations of the components will be apparent to those skilled in the art. -.. . .
`, The amount of saponified material, that is, the amount of the salt of rosin adduct, present in the aqueous suspension -~ which functions as the dispersing agent will be that which provides ~ `~
the desired stable dispersion. The æmount of saponified material present is expressed as percent of the total number of originally '~
available carboxyl (-COOH) groups present that have reacted to ~;
30 form the salt (sometimes referred to in the art as "the soap"), `

such, for example, as the sodium salt (-COONa). For convenience, . ~ .
- ~his value is set forth in the working examples as the "degree of .
-~ saponification". For example, in the examples a "degree of sapon-. ification of 4%" indicates that of the or~ginally available .:

: ."~, ' ', 574~67 ~ , carboxyl groups, 4% thereof have reacted with or been saponified with alkali. The degree of saponification can vary from 0.5% to 20~i; however, it is preferred to stay in the range of from about ~ ;
4% to about 10%. It will be appreciated that the acids of whieh rosin is comprised have one available carboxyl group. In the case where rosin has been reacted with an acidic compound, as above specified, to provide a fortified rosin or an adducted rosin, the reaction product will have additional available carboxyl groups as . . .
provided by the reacted acidic compound.
~` 10 Thus, the process of this invention consists essentially of homogenizing under a pressure of from about 2000 p.s.i.g. to ; about 8000 p.s.i.g. an unstable aqueous dispersion heated to a temperature of from about 125C. to about 180C., preferably about 130-160, said aqueous dispersion consisting essentially of, by

3 weight, about 50% to about 75% water and about Z5~i to about 50~
solids, the solids consisting essentially of, ~y weight, from 0%
¦ to about 95% rosin and from lOO~i to about 5% of an adduct reaction i produet of rosin and an acidic compound containing the -C=C-C=O
group, the amount of adducted acidic compound being from about ` 20 1% to about 20% of the total solids weight, a relatively small `1 amount of the rosin-base mat~rial being saponified, the amount 2 thereof, represented as a percentage of available carboxyl groups of the rosin-base material saponified being from about 0.5% to about 20~i. `
-~ In the following examples all parts and percentages are ~ by weight unless otherwise specified.
.
Example 1 illustrates the preparation of a rosin adduct.
`~ Example 1 Fumaric acid, 160 parts, is adducted at elevated temper-, atures with fused tall oil rosin (840 parts). The fumaric acid dissolves in the fused tall oil rosin and reacts therewith to pro-vide a reaction mass. The reaetion mass or product, after substan- ;~
tially all the fumarie acid has reacted with the talL oil rosin, is allowed to cool to room temperature (about 23C~. The reaction ~.... ~ :
:, - ~

~os7~7 mass is a mixture comprised of unreacted rosin and rosin--fumaric acid reaction product or adduct. The reaction product contains 16~ fumaric acid, substantially all of which has been reacted.
The reaction product has an acid number of 240.
The following examples illustrate the invention using ~;
as the anionic dispersing agent a rosin-base material soap.
Example 2 About 1940 parts of wood rosin, about 1160 parts of an adduct prepared in accordance with Example 1, ~290 parts of water, 10 and 370 parts of 10% aqueous sodium hydroxide are admixed and heated to a temperature of about 175C. The resulting heated mix~
ture is passed through an homogenizer at 3000 p.s.i.g. to form a dispersion which is immediately cooled to room temperature by passing it through a quench cooling loop. The resulting disper-sion has good stability and has a solids content of about 40~.
About 6% of the solids weight is adducted fumaric acid. The degree of saponification is 7.1%.
`Y` - Example 3 `~ About 3000 parts of 6% fumaric acid adduct of formalde~
~` 20 hyde treated tall oil rosin, 4730 parts of water, and 740 parts ;l of 10% aqueous sodium hydroxide are admixed and heated to a tem~
;~ perature of about 170C. The resulting heated mixture is passed through an homogenizer at 3000 p.s.i.g. to form a dispersion which : :
;~; is immediately cooled to room temperature by passlng lt through a ;¦ quench cooling loop. The resulting dispersion has good stability ~`~y and has a solids content of about 35%. About 6% of the solids -~i weight is adducted fumaric acid. The degree of saponification is `~i 15%. ~
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~i The sizing efficiency of each of the aqueous suspensions of Examples 2 and 3 were tested by preparing handsheets using vary-ing amounts of size solids. To prepare the handsheets, Rayonier ~-..:
~ bleached kraft pulp is suspended in standard hard water and beaten :
to 750 ml. S-R freeness in a Noble and ~ood cycle beater. Size additions are made to 2-liter portions of the beaten slurry which ,:
9 ~

has been diluted to 2.5% solids by weight. Sufficient alum is added to each sized slurry to provide a pH of about 4.5, and the slurry is then diluted to a consistency of 0.27~ in the propor-tioner, using acid-alum dilution water.
The dilution water is prepared by reducing the pH of water o moderate hardness to 5.0 with sulfuric acid, then adding -enough alum to provide 5 p.p.m. soluble aluminum. One-liter por-tions of proportioner pulp slurry are diluted further with acid-`~ alum dilution water to a deckle box consistency of 0.025% in order ;
to form 40-pound basis weight t24" x 36" - 500 sheet ream) hand-sheet using a Noble and Wood sheetmaking apparatus. A closed white water system is employed. Formed sheets are wet-pressed to 33%
1 solids cont~nt and then dried at 240F. on a steam drum drier.
-~j All handsheets are conditioned for two days at 72F. and 50% rela-~' tive humidity and are tested in this environment. Resistance to penetration by Test Ink ~2 is determined by use of the Hercules Sizing Tester. The time necessary for ink penetration to reduce light reflectance to 80% of the sheet's initial value is used to ` represent the degree of sizing.
Table I below sets forth photometer sizing results for the sizes of the examples at a size concentration of 0.5%. The ' size concentration is by weight and is based on the weight of the ;~
dry pulp. Thus, for example, a 0.5% size concentration indicates that 0.5% by weight of the solids content of the aqueous suspen-sion of the specified example, based on the weight of the dry pulp, is added.
Table I
Photometer Sizing as a Function Size of Example of Size Concentration 0.5%

As above set forth, anionic dispersing agents other than 1 those based on rosin can be used in preparing the dispersions of ,,, 10 ~- ' ` - :
this invention. The upper limit of the amount of such anionic dis-persing agents is critical since an excess may have an adverse effect on sizing and will vary according to the effect of the par-ticular dispersing agent. As much as 5% (based on the amount of rosin-~a~e material) dispersing agent can be used, though prefer-ably ~will be the upper limit. The lower limit is that which gives a stable dispersion with particles 0.1 to 1 micron in size.
The minimum amount for this requirement is about 1%, though in most cases 1.5~ will give better results. When the dispersing agent is used in combination with a rosin-base dispersing agent t as little as 0.1~ may be used.
The following examples illustrate the use of other anionic dispersing agents.
:: -Example 4 About 1000 parts of 7.5% fumaric acid adduct of formalde- ~
hyde treated tall oil rosin, 1425 parts of water, and 75 parts of `
Ultrawet 30DS ~30% solids sodium linear alkyl benzene sulfonate) are admixed and heated to a temperature of about 170C. The re-sulting heated mixture is passed through an homogenizer at 4200 p.s.i.g. to form a dispersion which is subsequently cooled rapidly to room temperature. The resulting dispersion has good stability and has a solids content of about 40%. ;~`
Example 5 About 1000 parts of 7.5% fumaric acid adduct of formalde-hyde treated tall oil rosin, 1800 parts of water, and 57 parts of Ultrawet 30DS are admixed and heated to a temperature of about 180C. The resulting heated mixture is passed through an homogen-izer at 2500 p.s.i.g. to form a dispersion which is subsequently cooled rapidly to room temperature. The resulting dispersion has :-good stability and has a solids content of about 35%.

~ Example_6 .'~
About 1000 parts of 6% fumaric acid adduct of formalde~
hyde treated tall oil rosin, 925 parts of water, and 85 parts of Ultrawet 30DS are admixed and heated to a temperature of about 170C.

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7~ 7 The resulting heated mixture is passed through an homogenizer at 3000 p.s.i.g. to form a dispersion which is subsequently cooled rapidly to room temperature. ~he resulting dispersion has good stability and has a solids content of about 50%.
Example 7 A 1~ solution of Tamol SN (sodium salt of condensed naphthylene sulfonic acid) in deionized water is pumped at the rate of 2100 parts per minute through a heat exchanger to heat it under pressure to a temperature of 170C., and then into an in-line mixer into which is also pumped at the rate of 1400 parts per minute molten adducted wood rosin (containing 6% fumaric acid) which was preheated to 170C. This blend is passed through a Manton-Gaulin homogenizer opera~ing at a temperature of 170C. and a pressure of ~000 p.s.i. The emulsion so formed is cooled rap-idly to a temperature below 80C. by introducing it into a cir-culating stream of previously cooled emulsion. The time at which the Tamol SN solution and the rosin emulsion were maintained above :
80C. was less than three minutes. The solids content of the . ~., stable emulsion so formed is about 40%.
Example 8 A 1.25% solution of DuponoI ME (duPont Company, sodium lauryl sulfate) in deionized water is pumped at a rate of 8Q parts per minute through a heat exchanger to heat it under pressure to a temperature of about 150C. and then into an in-line mixer into which is also pumped 40 parts per minute of molten adducted rosin which had been heated to about 165C. The adducted rosin used is a 6% fumaric acid adduct of formaldehyde treated tall oil rosin.
This blend is passed through a Manton-Gaulin homogenizer, the tem-perature being about 160C., and the pressure 3000 p.s.i. The emulsion is cooled rapidly to below 80C. by passing throu~h a heat exchanger. The contact time at which the aqueous solution and the emulsion are above 80C. is about two minutes. The solids content of the stable emulsion so formed is about 35%.

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lQ57467 Ex~ e 9 A 1.1~ solution of Aeroso~ OT (American Cyanamide, r~ -, di,octyl ester of sodium sulfosuccinic acid) in deionized water is used as the emulsifier, otherwise using the materials and pro-cedure of Example 7. A stable emulsion with a solids content of about 40~ is formed.
Example 10 A 2.5~ aqueous solution of Alipo~ C0436 (GAF Corporation, 58% ammonium salt of the sulfate ester of an alkylphenol poly- ~ ' 10 (ethylenéoxy)ethanol)is used as the emulsifier, otherwise using ' '~' the materials and procedure of Example 7. A stable emulsion with a solids content of about 40% is formed.
Example 11 ;~
A solution containing 0.5% sodium hydroxide and 0.2%
Duponol ME i~ deionized water is used as the aqueous phase in the procedure of Example 7. A stable emulsion with a solids content ;' of about 40% is obtained.
Example 12 ` The procedure of Example 2 is followed except that 31 '~
parts of Ultrawet 30DS is added to the sodium hydroxide solution. ' A stable emulsion with a solids content of 48% is obtained.
Example 13 ' A 1.5% solution of Duponol WAQE (duPont Company, sodium lauryl sulfate) in deionized water is pumped at a rate of 100 parts per minute through a heat exchanger to heat it under pres~
sure to a temperature of about 140C. and then into an in-line mixer into which is also pumped at a rate of 50 parts per minute at about 165C. a molten adducted tall oil rosin (containing 2.75% ' ' reacted formaldehyde and 8% reacted fumaric acid). This blend is passed into a homogenizer maintained at a temperature of about 155C. and immediately into a circulating stream of previously cooled emulsion to cool the emulsion immediately to a temperature below 60C. The solids content of the resulting stable emulsion was about 35%.

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7~7 Example 14 A 3% solution of Duponol WAQE in deionized water is used to emulsi~y the adducted rosin as used in Example 13 and using the same technique except that equal parts of the solution and molten resin was employed. A stable emulsion with a solids content of about 51~ is obtained.
' To determine the siyzing efficiency of the aqueous suspen-,~
sion of Examples 4 through ~, surface sizing experiments were performed using bleached kraft paper (40 lbs. per 500 24" x 36"
, 10 sheets) made at pH 6.5 with 0.5% added alum. The sheets were -~
! treated using a small laboratory horizontal size press by adding samples of the aqueous suspensions diluted to about 0.29% to the '~ nip of the size press and passing sheets of paper through the solu~
tion before being squeezed by the rolls of the size press. Under these conditions the sheets picked up about 70% of their weight of size press solution to give about 0.2% size applied to the ;" sheet. The sized sheets were dried about 20 seconds on a labor-atory drum dryer with the surface temperature about 200F. The ~ ` sheets were aged four days and then tested using number two test - :
20 solution with the Hercules Sizing Test to 80~ reflectance. The ~;

- following summarizes the results.
:
`, Hercules Sizing Test Size of Example ~esul'ts in Se'co'nds : . -''~ 4 ,,., 5 136 .
'-`` 6 115 ' ~`J 7 131 `' 8 141 . .
' 9 118 ,~, 30 10 112 ' 11 138 :
`'~ 12 133 ., .
~-' 13 125 A ` ~
'` 14 110 : ",'':
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing an essentially stable aqueous dispersion of rosin base material adapted for use in the sizing of cellulosic papermaking fibers which comprises homogenizing under a pressure of from about 2000 p.s.i.g. to about 8000 p.s.i.g. and at a temperature of from about 125°C to about 180°C an unstable aqueous dispersion containing, by weight, at least about 25% solids, the solids consisting essentially of, by weight, from 0%
to about 95% rosin and from 100% to about 5% of an adduct reaction product of rosin and an acidic compound containing the -?=?-?=0 group, the amount of adducted acidic compound being from about 1% to about 20% of the total solids weight, and, if necassary, removing from the dispersion any particles whose size is greater than about one micron characterized in that the process is carried out in the presence of an anionic dispersing agent.

2. A process as claimed in claim 1 further characterized in that the anionic dispersing agent is saponified rosin-base material, the amount there-of represented as a percentage of available carboxyl groups of the rosin-base material saponified being from about 0.5% to about 20%.

3. A process as claimed in claim 1 further characterized in that the anionic dispersing agent is a synthetic emulsifier, the amount of anionic dispersing agent being from about 1% to about 5% based on the emulsion solids.

4. A process as claimed in claim 3 further characterized in that the amount of anionic dispersing agent is from about 1.5% to about 2.5%.

5. A process as claimed in claim 2 further characterized in that the solids content is from about 30% to about 50% and the water content is from about 70% to about 50%.

6. A process as claimed in claim 5 further characterized in that the solids consist essentially of, by weight, from 0% to about 85% rosin and from 100% to about 15% adduct reaction product, wherein the amount of adducted acidic compound is from about 4% to about 8%.

7. A process as claimed in claim 6 further characterized in that the amount of the saponified rosin-base material is from about 4% to about 10%.

8. A process as claimed in claim 3 in which the anionic dispersing agent is a salt of an alkylaryl sulfonic acid.

9. A process as claimed in claim 3 in which the anionic dispersing agent is a salt of an alkyl half ester of sulfuric acid.

10. A process as claimed in claim 1 in which the anionic dispersing agent is a combination of saponified rosin-base material and a synthetic emulsifier.

11. An essentially stable aqueous dispersion of rosin-base material adapted for use in the sizing of cellulosic papermaking fibers which has bean prepared by a process which comprises homogenizing under a pressure of from 2000 p.s.i.g. to about 8000 p.s.i.g. and at a temperature of from about 125°C. to about 180°C. an unstable aqueous dispersion containing, by weight, at least about 25% solids, the solids consisting essentially of, by weight, from 0% to about 95% rosin and from 100% to about 5% of an adduct reaction product of rosin and an acidic compound containing the -?=/-?=O group, the amount of adducted acidic compound being from about 1% to about 20% of the total solids weight and, if necessary, removing from the dispersion any par-ticles whose size is greater than about one micron characterized in that the process is carried out in the presence of an anionic dispersing agent.