CA1043511A - Method of sizing paper - Google Patents

Abstract

Abstract of the Disclosure Paper products are sized with a sizing emulsion formed in the absence of high shearing forces and under normal pressures and containing 80 - 97 parts of a substituted cyclic dicarboxylic acid anhydride, 3 - 20 parts of a polyoxyalkylene alkyl or polyoxyalkylene alkyl-aryl ether or the corresponding mono- or diester, and water. The sizing step is accomplished by intimately dispersing the size emulsion within the paper stock prior to its passing through the drying stage of the paper-making operation in an amount which provides a concentration of the substituted cyclic dicarbox-ylic acid anhydride of 0.01 - 2.0%, based on the dry fiber weight. The improved size properties of the resulting paper product, e.g., resistance to water or acidic ink solutions, are achieved in this method using a smaller amount of size as compared to prior art sizing methods.

Description

~0~'~5~
This invention relates to an improved method for the sizing of paper and to the paper thus prepared. More particularly, the invention relates to an improved method of sizing paper and paperboard products using a mixture comprising hydrophobic substituted cyclic dicarboxylic acid anhydride and polyoxyalkylene alkyl or alkyl-aryl ether or the corresponding mono- or di-ester under specified conditions.
As used herein, the terms "paper and paperboard"
include sheet-like masses and molded products made from fibrous cellulosic materials which may be derived from both natural and synthetic sources. Also included are sheet-like masses and molded products prepared from combinations of cellulosic and non-cellulosic materials derived from synthetics such as poly-amide, polyester and polyacrylic resin fibers as well as from mineral fibers such as asbestos and glass.
It is recognized that paper and paperboard are often sized with various hydrophobic materials including, for example, rosin, wax emulsions, mixtures of rosin with waxes, ketene dimers, isocyanate derivatives, fatty acid complexes, fluoro-carbons, certain styrene-maleic anhydride copolymers, as well as the substituted cyclic dicarboxylic acid anhydrides more particularly described hereina~ter. These materials are referred to as sizes or sizing and they may be introduced during the actual paper making operation wherein the process is known as internal or engine sizing. On the other hand, they may be applied to the surface of the finished web or sheet in which case the process is known as external or surface sizing.
Sum~ary of the Invention It is the object of this invention to provide improved sizing of paper which is characterized by its reduced water and ink absorption as well as its increased .

. , 10~

resistance to aqueous acid and alkallne solutLons.
The sizing compound8 contemplated for U9Q in our sLze mixtures are substituted cyclic dicarboxylic acid anhydride~. More specifically, the sizing compounds correspond to the following structural formulas:
.

(~) 0 ~ ~-R - R' \ C' .
wherein R represent~ a dimethylene or trLmethylene radical and whereln R' i8 a hydrophobic group containing more thsn 5 carbon atoms which may be selectad from the cla8s conslsting of alkyl, alkenyl, sralkyl, or aralkenyl group~; ~nd ' Rx (B) C - C - CH - CH ~ CH - R
1. ` ' ' .
\C CH
. 0~
wherein R i8 an alkyl radical containing at least 4 carbon atoms and R Ls ~n alkyl radLcal containing ~t least 4 carbon ~toms, and Rx and Ry Qre interch~ngeable.
Specific examples of ~izing compounds fallLng within structure`(A) lnclude iso-octadecenyl succlnic acLd anhydride, n-hexadecenyl succinic ~cid anhydrid¢, dodecenyl ~uccinic acid anhydride, dodecyl succinic acid anhydride, decenyl 6uccinic acld anhydrlde, octenyl succinic acid anhydride, triisobutenyl succinlc acid anhydrldeJ etc. Siz-ing compounds in whlch R' contains more than twelve carbon -104;~
atoms are preferred. The sizing compounds of structure (A) are fully described in U.S. Patent No. 3,102,064 issued August 27 1963.
Specific examples of sizing compounds falling within structure (B) include (l-octyl-2-decenyl)-succinic acid anhydride and (l-hexyl-2-octenyl)-succinic acid anhydride.
The sizing compounds of structure (B) are fully described in copending Canadian application assigned to the assignees of the pre~ent invention, Serial No. 186,235 filed November 20, 1973.
According to prior art teachings, in order to obtain good sizing with the described sizing compQu~d iit is desirable that they be uniformly dispersed throughout the fiber slurry in as small a particles size as is possible to obtain. Tn usual practice of adding these sizing compounds to the paper stock prior to web formation, therefore, the sizing compound is added in the form of an aqueous emulsion prepared with the aid of emulsifying agents.
These prior art emulsification techniques which utiliz~d emulsifying agents which acted as protective colloids such as cationic or ordinary starches, gum arabic, gelatin, cationic polymers or polyvinyl alcohol, or that utilized surfact-ants in ~combination with the aforementioned emulsifying agents, however, suffered from several inherent deficiencies. A primary deficiency concerned the necessity of utilizing relatively com-plex, expensive and heavy equipment capable of exerting high homogenizing pressures, together with rigid procedures regard-ing emulsifying proportions and temperatures, etc., for producing a satisfactory emulsion of the substituted cyclic dicarboxylic ; acid anhydride size. Moreover, attempts to use the surfactants alone, i.e. without emulsifying agents, have been found to be totally unsuccessful from a commercial view. With the use of a surfactant, according to prior art, it has not been possible 104;~S11 to form a stable, small size particle emulsion and/or the emulsion did not produce sufficient sizing performance. In some instances, the resultant emulsion detrimentally affected other properties of the sized paper, for example, loss of wet strength. Another drawback noted with various emulsions prepared with certain surfactants, is demonstrated where on aging of the treated paper, many small hydrophilic spots were formed as evidenced-by an ink dip test.
Additionally, the use of many surfactants was found to create severe operational problems in the papermaking process - such as severe foaming of the stock. By the process of this invention, use of heavy equipment for producing an emulsion is eliminated, and more flexibility in preparing and utilizing the sizing mixure is permitted. Moreover, in preparing emulsions of the size mixtures herein according to the method of this invention, a smaller particle size-is readily achieved and the stability of the resultant emulsions is generally superior to those of the prior art. Additionally, use of the size mixtures of this invention results in significantly improved sizing perfor-mance (i.e. improved sizing is achieved with a given concentrationof size), and also results in the improved operability as evi-denced by reduced build-up of fiber and sizing agent on the press rolls of the paper machine.
It has now been discovered that size mixtures of substituted cyclic dicarboxylic acid anhydride and polyoxyalkyl-ene alkyl or polyoxyalkylene alkyl-aryl ether or the correspond-ing mono or di-ester in specified proportion readily yield improved sizing emulsions witho,ut the necessity of utilizing heavy homogenizing equipment. These mixture have been found to emulsify by merely stirring or passing through a mixing val~e or an aspirator. The emulsion thus produced is adequately stable 10~

for commercial purposes and possesses a sufficiently small particle size to produce excellent sizing of the resultant web.
It is also a feature of this invention that in one variation of the method, the size mixture may be used in the sizing method without any prior emulsification step. In this variation, the mixture is added to the paper stock preparation system with good agitation prior to the refining of the stock. The usual agitation of the stock when passing through refiners has been found sufficient to emulsify the mixture so as to produce excellent sizing properties in the resultant sized web.
The polyoxyalkylene alkyl or polyoxyalkylene alkylaryl ethers or corresponding mono- or di-esters useful herein comprise polyoxyethylene or polyoxypropylene alkyl and alkyl-aryl ethers or esters containing 5 - 20 polyoxyethylene ~or polyoxypropylene) units wherein the alkyl radical , contains from 8 - 20 carbon atoms and the aryl radical is preferably phenyl.
The preparation of these ethers and esters is known ~o those skilled in the art. Typical commercially available products useful in the method of this invention include Renex* 690 sold by ICI America, Inc., Wilmington, Delaware, Triton* X-100, Triton* X-205 and Triton* N-57 sold by Rohm and Haas Co., Philadelphia, Pennsylvania, Tergitol* NP-27 and Tergitol* TMN sold by Union Carbide Corporation, New York, New York, and Igepal* C0-630 sold by GAF Corporation, New York, New York, as well as PEG 400 Monooleate supplied by Finetex, Incorporated and PEG 600 Dilaurate sold by Armak Chemical Division of Akzona, Incorporated.
In accordance with the method of this invention, the size mixture is formed by mixing 80 to 97, preferably 90 to 95, parts of the aforemen-tioned cyclic anhydride with 3 to 20, preferably 5 to 10, parts of the selected polyoxyalkylene alkyl or alkyl-aryl ethers or esters. It is re-cognized that various combination of size compounds and/or polyoxyethylene * Trademark ~7 ~0~;~5~1 alkyl or alkyl-aryl ethers or es~ers may be used Ln preparLng a particular size mixture, as long as they fall within the scope of'this invention. In order to prepare an emulsion, the size mixture is generally added to water in sufficient quantity S so as to yield an emulsion containing the substituted cyclic dicarboxylic acid anhydride in a concentration of from'about 0.5 to 20%, by weight. The aqueous mixture is thereafter suffici-ently emul-sified merely by stirring with moderate to high speed agitation or by passing it'through a mixing valve, aspirator or orifice -so that the average particle size of thè resultant emulsion will be less than 3 microns. It is noted that in prepar-ing the emulsion, it is also possible to add the components of the size mixture to the water separately, and the emulsion may be prepared by a continuous or batch method.
As to actual use, no dilution of the emulsion is generally necessary. The thus-prepared emulsion is simply added to the wet end of the paper making machine or to the stock preparation system so as to provide a concentration of the substituted cyclic dicarboxylic acid anhydride of from about 0.01 to 2.0% based on dry fiber wei'ght. Within the mentioned range the precise amount of size which is to be used will depend for the most part upon the type of pulp which is being utilized, the specific operating conditions, as well as the particular end use for which the paper is destined. For example, paper which wil]: require good water resistance or ink holdout will necessitate the use of a higher concentration of size than paper which will be used in applicat'ions where excessive sizing is not needed.
As another embodiment of this invention, instead of adding the size emulsion to the stock preparation system or wet end, the size emulsion may be sprayed onto the surface of the formed web at any point prior to the drying step In this embodi-ment, the emulsion is used in the concentrations as prepared, and is sprayed onto-the web so as to provide a concentration of size of from about 0.01 to 2.0% based on dry'fiber weight.

104;~511 .
Where the qize mixture Ls added to the ~tock preparation system prior to refining, it i8 unnecessary to carry out a separate emulqificatlon step. The amount of size mixture added in this manner should be such as to provide a concentration of RubstLtuted-cyclic dicarboxylic acid anhydride of from about 0.01 to 2~'0% based on dry fLber weLght.
An important actor in the efective utilization of the size mixtures hereLn involves their use in con~unction with a material which i8 either cationic or i8 capable of ionlzing or dissociating in such a manner a~ to produce one or more cations or other positively chsrged moieties. These cationic agents, a~ they hereinater will be ref~rred to-, have been found u~eful as a mean~ for aiding the retention of the -~u~stituted cyclic dicarboxylic acid anhydrides as well as for ~r~ git~ ~att~é~ L~t~D clo~e proximity to the pulp fibers.
Among the materials which may be employed a~ cationic agents Ln the method of this invention, one may li-st alum, aluminum chloride, long chaLn fatty~amines, amLne-containing synthetic polymers (primary, secondary, tertiary or quaternary amine), sodium alumlnate, chromic sulfate, substituted polyacrylamlde, animal gluej catLonic thermosetting re~ins and polyamide polymers. Of particular use as cationic agents are various cationic starch derivatives includLng primary, secondary, tertiary or quaternary amine starch derivative~ and other cationic nltrogen ~ub~tituted starch derivatives~ as well as cationic sulfonium and pho~phonium starch derlvatives. Such derivatives mfly be prep~red ~rom alI types of ~tarche~ includ-ing corn, tapiocs, potato, waxy maize, wheat and rice, More-over they may be in theLr original granule form or they may be converted to pregelatinized, cold water soluble products.
Any of the above noted cationic agents may be added to the stock, i:e. the pulp slurry, either prior to, along with or after the additlon oE the size mixture or ~ize 104;~511 , emulsion, and mny take place at any point in the paper maklng proces~ prlor to the ultlmate conversLon of the wet pulp into a dry web or sheet.
With re~pect to the amount of cationic agent necessary, under ordinary cLrcumstances, the cfltlonlc agent is added to the stock ~ystem Ln an amount of at le~st 0.01%, preferably 0.025 to 3.0%, bfl8ed on dry fiber wei~ht. While smounts in excess of 3%, may be used, the benefit~ of using lncréased amounts of catlonic agent for sizing purposeR ~re usually not economlcalIy ~stified.
~ Subsequent to`the additLon of the slze emulsion and c~tionlc agent, the web i8 ormed and dried on the papermaking machLne in the ugual manner. Whlle full slzlng 18 generally - schieved immedLately of the paper machine, further improve-ments in the water reslstance of the paper prepared with the 51ze mLxture8-of this invention may at time8 be obtained by curing the resulting web8, ~heets or molded products. ThLs curing proce~s generally involves heating the paper at temperatures in the range offrom 80~oito 150C for a period of fro~ 1 to 60 minutes. However, it i8 to be noted that post curing is not es~entlal to the successful operation of the Improved sizing method described herein.
The 8 ize mixturesio~ the present invention may, of course, be succe~sfully utili~ed for the sizing of paper prepared from all type~ of both c`ellulosic and combinations o cellulo8ic with non-cellulosic fibers. The hardwood or softw~od cellulosic flber~ which may be used include bleached and unbleached sulfate ~kraft), bleached and unbleached sulfite, bleDched and unble~ched soda, neutral ~ulfite semi-chemical, groundwood, chemi-groundwood, and any combination of these fibers. ~hese designation8 reer to wood pulp fiber~ which have been prepared by means of a variety of proce~ses which are used in the pulp and paper industry.
In addition, synthetic cellulo31c fibers of the viscose rayon or regenerated cellulo~e type can al90 be used, fl8 well as :

iO435~1 recycled wa~te p~pers from various source~.
All types of pigments and fillers may be Ddded to the paper in the usual manner whicb iB to be sized in accord~nce wLtll thls Lnvention. Such material~ include clay, talc, tLtanium dioxLde, calcium carbonate, calcLum sulfate, and diatomaceou~ earths. Other additlves includln8 alum, as well as other slzLng compounds can fll90 be used with the size mixture8 described heraLn.
The uBe o the size mlxtures descrLbed herein ln accordance wLth the method of this Lnventlon ha3 been found (as will be illustr~ted ln the exumples) to yLeld paper .
having improved size propertie~, for example, resi8tance to water or ucLdic lnk solutLons. In othe~ words, a specLfied degree of size propertles in paper can be achieved with a smaller amount o slze when the slze is utilized in accord~nce with the method of thi8 lnvention rather than by method8 known ln the p~ior art, Moreover, it is a further advantage ~hat use of the 8ize m~xtures herein i8 not limlted to any particular pH
range whfch thus allows for their utllizatlon ln the trestment of neutral and alkallne pulp, as well as acidlc pulp. The size mixtures may thus be u8ed ln combination with alum, whLch la very commonly u~ed in makLng paper, as well a~ other acldic m~terials. Conver~ely, they may also be used with calc~um carbonate or other ~lksline materials in the ~tock.
A further advanta~e o these size mixture8 i8 that they do not detract sib~Lflcantly from the strength of the paper ~n the nor~l concentrations employed ln the Lndu~try and when used with certsin ud~uncta will~ infact, increase the strength of the finished sheets. An addltional advantage found in the u~e of these size mLxtures i8 that only drying or mild curing conditions are requLred~to develop full slzing value.
The following exsmples will further LllustratQ the embodiment of the present inventlon. In these ex~mples, all parts given are by weigllt unle8s otherwise noted.
_ 9 _ .

1~43S11 EX~IPLE I
rhLs example illu3trate~ the use of a ~ize mixture repre~2ntative of the size mLxtures of this invention utilized in the form of ~n aqueous emulsion. This emuls10n i8 compared, in terms of particle size and water r-e~i~tance of ~he rèsulting ~ized paper, with a conventionsl emulsion whereln substLtuted cycllc dicarboxylic acid anhydride Ls emulsif1ed wLth cationic starch. A urther comparison is msde with ~ rosin/alum slzing method as commonly employed ln the paper industry. The much greater ease of emul~ification of the 8ize mixtures of this lnvention Ls also demonstrated by the procedure-u~ed in prepar~n~ the sizing emulsion~ prior to their addltion to the pflper stock sy~tem. The ability to size paper effectively with or without alum in the stock i3 al80 shown.
The size mixtur~ was prepared by combining (A) 10 parts of ~ polyoxyalkylene alkyl-aryl ether wherein thè slkyl group contained 9 carbon atoms, the aryl r~dics~ was phenyl and the polyoxyalkylene moiety was fonmed with 10 moles of ethylene oxide ~Renex 690~ ~d (B) 90 parts of substltuted cyclic aïc~rboxyilc ac1d anhydrLde wherein the alkenyl groups of the mixed anhydrides contained 15 to 20 carbon atoms ~hereinafter referred to R~ ASA). Other material~ equivalent to Rene~ 6gO include Triton N~101 and Igepal GO-63~.
An emul~ion was t`hen formed by ugitatlng 2 parts of this mixture with 98 parts of water using a propeller-type mixer at moderate speed for 10 seconds (F.mul~ion ~ A simll~r emulsion w~s al30 ~ormed by pà~sin~ thls size mixture through a slmple a~plrator, together with ~ constant stre~m of water, ~o yield lX concentration of size mixture in one pass, The emulsion W~8 thus ormed almost inatantaneously (Emulsion ~2).
For comparL~on, 8 conventional aqueous emulsion of~
ASA was prepared by first cooking 10 parts of the beta-diethyl 104;~
, . . .
aminoethyl chloride hydrochloride ether of corn starch, who8e preparation i8 described in ~xample I o~ U, S Pstent No.

2,813,093, in 90 part~ of water whLch was heated in a boiling water bath. The dispersLon of the cationic starch derivative, after being cooked for 20 minute~, was cooled to room temperature and transferred to a high speed agitator whereupon 5 parts of ASA were slowly added to the agitsted di8per~ion.
Agitation was continued for about 3 minutes snd the resulting emul~ion wa~ then diluted by the addition of water to equal a total of 1,000 parts, 0.5% solids (Emulsion #3).
Calcuiated amountA of the emulsions prepared as descrlbed above were added'to aqueous slurrLes of bleached sulfate pulp having a William~ freeness of 400, a consistency of 0.5% and a pH of about ~. 6, 80 as to yield the ~ollowing lS concentration8 of ASA on dry fiber weLght: 0.10, 0.20 and 0.40Z, The cationic ~t~rch'u~ed in making Emulsion #3 was ~, sdded to the respective pulp ~lurry subsequent to the addltlon of Emulsions #1 and #2 in a concentration of 0~4% on dry fiber weight to retain these'materials in the sheet. In another variation of this procedure, 4% alum, based on dry fLber weight, was added to the pulp slurry before addition of the sizing emulsion~. Sheets were formed and dried in accordance with TAPPI ~tandards, then cured for 1 hour at 105C. and conditloned overnight at 72 F. and 50% R.H. before testin8.
The basi~ weight of these ~heets was 55 lbs./ream (24" x 36" -500 sheet~). ' ' ' In comparing the water resistance of these sheet~, use was made of a dye test employing cryGtals of potassium permanganate and an acid lnk psnetration test. In the dye test seversl cry~tal~ of pota~8ium permanganate are placed on the upper ~urface of a swstch of test paper which i8 then set afloat in diQtilled water at room temperature. As the water is ab~orbed into the paper the cry~tal~ are moi~tened and impart a characteristlc deep violet color to the paper. The ~4351~ .
. 1 . , .

.
time measured in second~ required ~or an end-point where three colored spots first appear on the paper surface 1~
noted and i9 Ln dlrect relation to the water resistance since 8 more water re~istant paper will retard the moistening o~
the~permangnnate crystals which had been placed upon it8 upper 8urface.
The acid Lnk penetration test ls a compari60n test wherein 8 ~watch of test paper is floated in a dish of acid ink (pH 1.5) at 100F. and the time measured in seconds . required ~or the ink to penetrate through the paper to reach ~n end-point where about 50% of the paper is colored is noted.
The following table presents data on the various paper sheets which were compared in the described testing procedures.

~veruge %
Particle by Acld Ink Size of Weight Penetration ~MnO4 Sheet Slzing Emulsion of Dry Alum ~Time in (TLme in No. Emul~lon ~Microns) Pulp Addition Seconds) S~conds) 1, Emul~ion #1 ~ 1 0,1 ~one 25 53 2. Emulsion #1 c 1 0.2 " 275 72

3. Emulsion #1 ~1 0.4- " 430 77

4. EmulsLon #2 c l 0.1 " 70 53 S. Emulsion ~2 Cl 0.2 " 140 . 74 6. Emulsion #2 1 0.4 " 320 87 7. EmUlBion #3 2-3 0.1 " 12 54 (Control) 8. Emulsion #3 2-3 0.2 " . 40 67 (Control) 9. Emul6ion ~3 2-3 - 0.4 " 65 75 (Control) 10. Emulsion #1 ~ 1 0.1 4% 100 58 11. Emulsion #1 C 1 0.2 4% 145 70 12. Emulslon #1 < 1 0.4 4% 190 87 ; 13. Emulsion #2 - ~1 0.1 47O 110 57 14. Emulsion #2 .Cl 0.2 4% 150 68 15, Emul~on #2<l 0.4 4% 205 88 16. Emul~ion ~3 2-3 0,1 4% 90 65 (Control) 17. Emulsion #3 2-3 0.2 47O 130 . 73 (Control) 18 . Emul~ ion #3 2-3 0.4 4% 170 84 L9. Rosln (Control) - 1,0 4% 55 67 20, Blank - None None 0 0 ~0~a3Sll The above data clearly ~hows the greater ease of preparation and ~uperiority of the ~ize mLxtures of this invention, both in terms o the small particle size of emul8Lon8 formed with these compo~ltions and in tèrms of water resistance imparted to the sized paper over a range Ln level of addition typically employed in the industry. It i8 al80 cLear that the~e compo~ition6 demonstrate superior sizing both in near-neutral and alum-contalning (acldic) stock 8 y8 tems.
EXAMPLE II
This example illustrate8 the use of~ize mixtures of this invention wherein various s~bstituted cyclic dLcarboxylic acid anhydrides are utilized ~n mixtures with polyoxyalkylene alkyl and alkyl-aryl ethers.
In this example, the polyoxyalkylene alkyl aryl ether was the same material described in Example I-and was mixed Ln a ratlo of 20 parts with 80 parts of the anhydride.
- The substltuted cyclic dicarboxyIic acid anhydrides incorporsted in the mixtures of this example were then var~ed as follows: Mixture #l - the ASA descrlbed ln Example I; Mixture #2 - iso-octadecenyl succinic acid anhydrlde;
Mixture $3 - hexapropylene succlnlc àcid anhydride;
Mixture #4 -(1-octyl-2-decenyl)~uccinic acid anhydrLde, i.~.
the reaction product of maleic anhydride and octadecene-9~
Emulsions of these mixture~ were prepared Ln the same manner u~ed to prepare Emulsion #l described in Example I.
Calculated amounts of the emulsions were added to separate aqueous slurries of bleached ~ulfate pulp having a freeness of 400, a consistency of 0.5% and a pH of about 7.6.
~he cationic starch of Example I was also added to the separate pulp slurries. Sheets were formed and dried in accordance to TAPPI standards and thereafter conditloned and tested as de~cribed ln Example I. The basi~ weight of these 10~3SlI
sheets was 55 lbs./ream (24" x 36" - 500 sheets). .All additions were made at a concentration of 0.2% substituted cyclic dicarboxylic acid anhydride.and 0.4% cationic starch by weight of dry pulp. Following were the results obtained:

Average . Acid Ink Particle Size Penetration KMnO4 Size of Emulsion (Time in (Time in Mixture No. (Microns) Seconds) Seconds) 1 ~ 1 225 73 2 1-2 -lO0 40 3 < 1 240 81 4 < 1 -- 600 8~
This example clearly shows that various substi-tuted cyclic dicarboxylic acld anhydrides may be used to prepare size mixtures within the scope of this invention.
EXAMPLE III
. This example illustrates the use of size mixtures of this invention wherein different polyoxyalkylene alkyl or alkyl-: 20 aryl ether or the corresponding mono- or di-ester compounds are - -utilized in the mixture with substituted cyclic dicarboxylic acid anhydride.
In this example, the substituted cyclic dicarboxylic acid anhydride was the same material (ASA) described in Example I
while the polyoxyalkylene alkyl and alkyl-aryl ether or ester compounds used in the size mixtures were varied, Size mixtures used in this example were prepared as follows: Mixture #l -

5 parts of the polyoxyalkylene alkyl-aryl ether described in Example I were mixed with 95 parts ASA; Mixture #2 - 15 parts of the polyoxyalkylene alkyl-aryl ether described in Example I
were mixed with 85 parts ASA; Mixture #3 - 10 parts of a polyoxyalkylene alkyl-aryl ether wherein the alkyl group contains 9 carbon atoms, the aryl radical is phenyl and the polyoxyalkylene moiety was formed with 5 moles of ethylene oxide (Triton N-57) were mixed with 90 parts of ASA; Mixture #4 -10 parts of a polyoxyalkylene alkyl ether wherein the alkyl groupcontains 12 carbon atoms and the polyoxyalkylene moiety was formed with 6 moles of ethylene oxide ~Tergitol TMN) were mixed with 90 parts ASA; Mixture #5 - lO parts of a polyoxyalkylene alkyl-aryl ether wherein the alkyl group contained 9 carbon atoms, - 10 the aryl radical was phenyl and the polyoxyalkylene moiety was formed with 15 moles of ethylene oxide (Tergitol NP-33) were mixed with 90 parts ASA; Mixture #6 - lO parts of a polyoxy-ethylene monoleate ester wherein the molecular weight of the polyoxyethylené moiety was 400 (PEG 400Moncoleate) were mixed with 90 parts of ASA; and Mixture #7 - lO parts of polyoxyèthylene dilaurate ester wherein the molecular weight of the polyoxyethyl-L
ene moiety was 600 (PEG 600 Dilaurate) were mixed with 90 partsof ASA. Each ofthese mixures was then agitated in water to yield emulsions containing 2 parts size mixture and 98 parts of t water. The emulsions were then addèd to a 0.5% consistency pulp ; slurry containing bleached sulfate pulp beaten to a freeness of 400 and at a pH of approximately 7.6 to yield 0.2% ASA on weight of dry fiber. The cationic starch described in Example I was then added to the pulp slurry to yield 0.4% cationic starch on weight of dry pulp. Handsheets thereafter were formed, conditioned and tested in the dye test as described in Example I.
Following were the results obtained.

' r 104351~

Average Particle Size of Emulsion KMnO4 -Size'Mixture No. (Microns) ' (Time'in'S'econds) 1 1-2 . 98 2 ~ 1 93 3 < 1 104 4Approx. 1 99 : ~ 5Approx. 1 96 6Approx. 1 76 7 -Approx. 1 86 - This examplè clearly shows that various polyoxy-ethylene alkyl and alkyl-aryl ethers and the corresponding mono- and di-esters, within the scope of this invention, can be used interchangeably in size mixtures.with substituted cyclic dicarboxylic acid anhydrides to yield excellent sizing performance.
EXAMPLE IV
; ' This example illustrates the use of our novel size mixtures by direct addition to a papermaking stock system in .
unemulsified form.
Size Mixture #l prepared from 90 parts ASA (described in Example I) and 10 parts.of polyoxyalkylene alkyl-aryl ether (described in Example I) was added directly to a slurry of bleached sulfàte pulp at l.5~/O consistency in a laboratory ~' Valley beater and beaten very lightly for a few minutes.
Similarly,Size Mixtures #2 and #3 were prepared from 90 parts ASA and 10 parts PEG 400Monooleate or 10 parts PEG 600'Dilaurate.
' respectively,and these mixtures were also added directly to the slurry. The Fulp was then diluted to 0.5% consistency, and 0.4% on dry fiber weight of the cationic starch described : ~ - 17 -1()43S1:1 in Example I was added separately to the slurry to act as a retention aid during sheet formation. Sheets were then formed, conditioned and tested in the dye test as described in Example I. The basis weight of these sheets was 55 lbs./
ream (24" x 36" - 500 sheets~. Following are the results obtained.

~/0 ASA by Weight KMnO4 Size Mixture No. on Dry Pulp (Time in Seconds) , 0 1 0.2 75 2 0.2 40 - 3 0.2 39 Blank None 0 The self-emulsifying properties of these size mixtures are demonstrated by the excellent sizing value achieved when they are added to the stock without prior - emulsification in water. Consequently, the considerable :

, - 17a -1()4~1~ .
`:
ease and versatility in the use of the size mixtures of this lnvention can be readily seen.

EXAMPLE V
.
This example illustrates the abLllty of ~ize mixtures-of this invention to readLly 8 i ze paper containing I high levels of inorganic filler. In thLs example, the - size mixture used was the same as de~crlbed in Example l.
Prior to addltion, the slze mixture was emulaified (Emulsion A) ~ in the same manner as described for the prepsration of Emulsion #2 ln Example I.-- For comparison purposesJ a conventional sizing emulsion (Emulsion B) was prepared in accordance with the method described to prepare Emulsion #3 in Example I. Each emulsion was then added to 1) a 0.5%
consistency ~tock slurry containLng bleached ~ulfate pulp with 20% Kaolin clay and 4% alum on dry fiber weight; and 2) a 0.5% consistency stock siurry containing blesched sulfste pulp with 20% calcium carbonate on dry fiber weight. The pH of the calcLum carbonate-contaLning stock slurry was approximately ~.5, while the pH of the clay-containing slurry was approximateiy 5.5. Each emul~ion wss added to the stock at a level to yLeld 0.4% ASA on dry fiber weLght. For retention purposes, 0.8% of the cationic starch described in Example I wa~ added to the pulp slurry following additlon of Emulsion A. Sheets of 55 lbs.~lream (24" x 36" - 500 sheets) basis weight were then formed and condLtioned in the manner described in Example I and tested sccordingly. Following are th¢ results obtained:

.

., - T~BLE 5 .
Acid Ink Sheet Size Added FillerPenetr~tlon KMnO4 No. Added (Time ln Sece.) (Time Ln Sccs.) 1Emul8ion A 20% Clay115 75 2Emulsion A 20% CaC03450 68 3Emulsion B 20% ClaylO0 70 ~Control) 4Emul~on B 20~h CaC03325 56 lQ (Control) 5Blank 20% Clay 0 0 The above data clearly shows-the improved ~izing achLeved with the slze mixture~ o~ thls invention in highly filled sheet8 and under both acid and alkaline stock conditions.
: ' EX~PLE VI
.
This example lllustrate8 the use of a 3ize mixture representative of the slze mixture6 of this invention to ~ize paper made:~ith different types of pulp8.
In thi~ example, the 8ize ~ixture u8ed W88 the same as described in Example I and was emuls~fied ln the same ma~ner as described ~or the preparation of EmulsLon #2 in Example I. The emulsion wa~ then added to various pulp slurrles prepared at 0.5Z consLstency, a freeness of 400 and pH of approxlmately 7.6 in amount~ to yleld 0.2~ ASA on dry fiber weight. In all ca~e~, 0.~% on dry flber weight of the ; catLonic starch described in ExMmple I was added to the pulp slurries separ~tely to retain the 8ize mixture during sheet formation. Sheet9 of 55 lb8.ream (24" x 36" - 500 sheet~) basis weight were then formed from each pulp slurry conditioned and tested in the dye teRt in the manner de~crlbed ln Example I.
Following are the re~ults obtained:

.

104;~

K~nO4 Sheet No Tvoe oE Pul~ (Time in Second~
1. Bleached Hardwood Sulfate 69 2 Bleached Softwood SulfLte 83 3 -Unbleached Softwood Sulfate 76 4 Groundwood' 58 ' The above data, together with data in other'examples, clearly shows that the si~e mixtures'of this invention can be effectively used to sLze variou9 types of pulp8 commonly used in.the manufàcture of paper.

EXAMPLE VII
' ~ is example illustrates the use of varlous types of catlonic agents in con~unctLon.wlth'the size m1xtures of thi~ invention. In this example, the size mixture used was the same a~ described in Example I.snd was emul~ified, prior to the addition to the pulp slurry, in the same manner d'essrlbed for the preparatlon of EmulsLon #2 in Example I.
The emulsion was added.to purtions of a 0'.5% consistency pulp slurry containing bleached sulfate pulp beaten to a ' . ~freeness of 400. Subsequent to the addition of size emul~ion, .. different cationLc agents were added to separate slurries in order to retain the size emulsion in the web during-sheet - formation. An amount of size emulsion was added so as to 25 . yield 0.2% ASA on dry iber weight in'each case, while the ' ''~
amount of cationic agent was varied. Sheets of 55 lbs./ream (.24" x 36" - 500 sheets) basi~ weight were then ~ormed from each slurry, conditioned and tested in the manner described ln Example~I. Following are the results obtained;

_ 20 -la4~

T~BLE ?
Acid Ink % on Dry Penetration KMnO4 Sheet Fiber (Tlme in (Time in 5 No. Cationic Agent Weight Second~) Seconds) 1 Cationic corn starch 0.4 135 72 2 Polyflminoethyl acrylate resin 0.2 600 76 3 Polyamide-amine resin 0.2 600 85 4 PDlyethylene imine resln 0.2 85 50 Pol~acrylamide-~mine resln 0.2 30 68

6 Cationic potato starch Q.4 120 70

7 Alum 4.0 65 77

8 None (Control) - 0 0 The above data clearly shows that various cationic agents can be effectively employed to retain the size mixtures of this invention in the web during the sheet forming stage.
EXAMPLE VIII
This example illustrates the improved operability of these sLze mixtures when used on an actual papermaking machine. More specifically, this example Lllustrates the elimination of buildup and picking tendencie~ crea~ed by sizing agents on the wet press rolls of a paper machine. This buildup of fiber on the wet press rolls causes disruptlon of the sheet surface and, in severe ca8es, will actually tear the sheet causing the traveling web to break at th~t point.
Sizing was me~sured in thi3 ex~mple by means of a Cobb test run ~n the top ~ide of the sheet in accord~nce with TAPPI
5tandard M~thod T441 os-69. This test measures the amount of water absorbed by the sheet surface in a specified period of time (in this case, 2 minutes) and is expre~sed in term~ of ~rams per ~q. meter. Thus, lower values represent greater wster resistance and better ~izin~.

104~511 A series of tests were conducted on a Fourdrinier paper machine wherein the press section consisted of two main presses followed by a smooth-ing press, each press consisting of a top and bottom roll. The first press consisted of a straight-through plain press with a standard rubber covered top roll as commonly used in the industry and the second press was a plain reversing press with a composition (Microrok*) covered top roll, also common-ly used in the industry. The smoothing press consisted of a straight-through set of rolls with a metal surfaced (Press-Tex*) top roll and com-position-covered (Micromate*) bottom roll. The basic papermaking furnish consisted of a very lightly refined mixture of approximately 80% bleached hardwood kraft pulp and 20% bleached softwood kraft pulp. The sizing agents were added continuously to the stock preparation system and a sheet of paper-board was formed at approximately 123 lbs. per 3,000 sq. ft. basis weight.
Buildup on the press rolls due to picking was ascertained under the indicated conditions on each of the p~ess rolls and noted in descriptive terms: None, slight, moderate, heavy, etc.
Sizing emulsions were prepared as follows: Emulsion A (a control) was prepared by cooking the cationic starch described in Example I at 5%
solids at 200F. for 30 minutes. The cooked starch solution was then cooled to 130F. and mixed with the substituted cyclic dicarboxylic acid anhydride of Example I (ASA) and emulsified by passing through commercial homogenizing equipment at 300 p.s.i.g. Emulsion B, representing an embodiment of this invention, was prepared by continuously premixing through a static mixer 90 parts of ASA with 10 parts polyoxyalkylene alkyl-aryl ether (as described in Example I), then passing this size mixture through an orifice with a continuous stream of water to yield an emulsion containing 2 parts of size mix*ure in 98 parts of water. For retention purposes, 0.35% cationic starch on * Trademark ~ . . ..

` 10~3511 .
weight of dry fiber was added subsequent to the addition of Emulsion B. Five pounds of alum per ton of stock were added to ad~ust stock pH to approximately 5.5 when Emulsion A and B were used. For further comparL~on, rosin was al80 used as a sizing agent in these tests. Following are the results obtained:

- ` TABLE 8 _ _ .__ Buildup Noted After Running 15 Min. Cobb Smoothing Sizlng Addition to Stock . 1st Press 2nd Press Pre~s (Gm/M ) l. Base Sheet - No AdditLves None None Slight 402 2, 1% Rosin + 2% Alum (.Control) Moderate Moderate Moderate 34 ~ 3. 0.25% Emulsion A (Control~ Heavy Moderate Heavy 32 4. 0,25% Emulsion B None None Slight 29 The concentrations of the variou~ ingredients listed in the above table sre expressed in terms of per cent active lngredient by weight of dry pulp.
The above results clearly illu6trste the lmproved machine operability and excellent wster holdout imparted by the slze.mixtures of this invention when compared to conventional 6izlng method~.employed in the industry.

EXA~lPLE IX
- This example lllustrates the excellent re~istance to acidic and alkaline solutions which i8 di8played by the paper whlch has been`prepared with our novel size mixture6.
An aqueous emulsion prepared with the s~sme slze mixture and in the same manner u6ed to prepare Emulsion #~ in - Example I was fldded to a bleached sulfate pulp slurry havlng a freeness of .400 and a consistency 0.5%, The cstlonic ~tarch of Example I wa9 then added to the stock as a retentlon aid for the size. Sheets containing 0.4% ASA and 0.8% cationlc starch were formed and condltioned as descrLbed in Example I.

` 1043511 The ~heets were tested by means of a modifLed potassium permanganate test wherein 801utlon6 of 10% lactic acid ln one case and 10% sod1um hydroxide in another case were used as the test fluLd, along with distilled water as a control, For a further comparieon, sheets were formed and tested in the same manner wherein 1% rosin and 4% alum on dry fiber welght was added to the stock for s1z~ng Ln place of our sLæe mlxture. Followlng are the results obtained;
.
TAB~E 9 KMnO4 Penetration Tlme tSeconds~
.
Sheet Distilled Lactic Sodlum No. Additive Water - AcLd Hvdroxide 1 0.4~/~ ASA Mixture 111 95 65 2 1.0% RosLn/4% Alum 70 60 25 This example clearly shows the excellent resistnnce imparted by these ~ize mixtures to penetration by both acidic and alkaline flu~ds.
In summary, the invention is seen to provide the practltioner with a novel size mixture useful in the manu-facture of sLzed paper p~oducts~ The size mixture is easily emulsified and the emulsion or size mlxture per se may be utllized under a wide variety of papermaking conditions to provide ~ized paper products characterized by their reduced water and ink ab~orption as well as their ~ncreased resi~tance to aqueous acid and alkaline solutions at low levels of addition. Variations may be made in proportions, procedures and materials without departln~ from the scope of this invention, ' r

Claims (7)

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

1. A method for sizing paper products comprising the steps of

1. providing a paper stock system;
2. forming, in the absence of high shearing forces and under normal pressures, a sizing emulsion consisting essentially of:
a. from 80 to 97 parts of substituted cyclic dicarboxylic acid anhydride corresponding to the formula (A) wherein R represents a dimethylene or trimethylene radical and wherein R' is a hydrophobic group containing more than 5 carbon atoms which may be selected from the class consisting of alkyl, alkenyl, aralkyl, or aralkenyl groups;
(B) wherein R is an alkyl radical containing at least 4 carbon atoms and Ry is an alkyl radical containing at least 4 carbon atoms, and Rx and Ry are interchangeable;
(C) wherein Rx is an alkyl radical containing at least 5 carbon atoms and Ry is an alkyl radical containing at least 5 carbon atoms and Rx and Ry are interchangeable;
b. from 3 to 20 parts of a polyoxyalkylene alkyl or polyoxyalkylene alkyl-aryl ether or the corresponding mono- or diester selected from the group consisting of:
i) ii) HO-[(CH2)i-CH2-CH2-O]m-R-CnH2n+1 iii) HO-[(CH2)i-CH2-CH2-O]m-CnH2n+1 iv) wherein x and n are integers in the range of 8 to 20; R is an aryl radical; m is an integer in the range of 5 to 20; and i is 0 or 1; and c. water;
3. forming a web from the paper stock system;
4. intimately dispersing said emulsion within the paper stock either before or after formation of said web but prior to passing said web through the drying stage of the paper making operation in an amount sufficient to provide a concentration of the substituted cyclic dicarboxylic acid anhydride of from 0.1 to 2.0%, based on dry fiber weight.

2. The method of claim 1 wherein the sizing emulsion is formed in situ within the paper stock system.

3. The method of claim 1 wherein the sizing emulsion is formed prior to introduction into the paper stock system.

4. The method of claim 3 wherein the size mixture is emulsified with water in a sufficient quantity to yield an emulsion containing the substitut-ed cyclic dicarboxylic acid anhydride in a concentration of from 0.1 to 20%, by weight of the total emulsified size mixture, prior to addition to the paper stock system.

5. The method of claim 3 wherein the size mixture in the form of an aqueous emulsion is sprayed onto the formed web prior to the drying operation.

6. The method of claim 1 wherein there is dispersed within the paper stock prior to the conversion of the paper stock into a dry web at least 0.01%, based on dry fiber weight, of a cationic retention agent.

7. The method of claim 1 wherein the sizing emulsion is formed with a polyoxyalkylene alkyl-phenyl ether selected from the group consisting of;
wherein n is an integer in the range of 8 to 20; m is an integer in the range of 5 to 20; and i is 0 or 1.