CA1068055A - Paper sizing process - Google Patents

Abstract

OTTO B. WURZBURG
IMPROVED PAPER SIZING PROCESS

Abstract of the Disclosure A method of sizing paper employing novel improved derivatives of cyclic dicarboxylic acid anhydrides and paper sized therewith are described.

Description

106~30SS
T~i8 invent~o~ ~ela~e~ to a proc~s for the B izing of psper and to the i~proYed paper thus prepared. More par~lcularly, thi~ ~nvention rel~es to no~el sizing agents for u8e in the ~lz~ng of paper and paperboard products.
It i8 the ob~ect of thiA inventlon to provlde improved slzing agents whose uBe results ln the preparation of paper whlch i~ characterlzed by its reduc~d water ~nd ins ab~orption as well a~ it~ resistance to a~ueou8 acid and alkaline 801utl0n8. A fur~her ob~ect of this invention -- 10 inYolves the u~e of sizing age~ts which msy be employad with 811 t~pe~ of psper pulp over the complete range o~ pH
conditions whlch sre normally enco~ntered in paper manufacturing.
An ~dditional ob~ect involves the use of sizing ~gent~ which sre fully c~mpatable with slum and ros~n a8 well as wi~h the various ~illers, pigments and other chemicals which may be ~dded to p~per.
As used herein, the term8 "paper and pap~rboard"
iuclude sheet-like masses ~nd moldsd products msde from fibrous cellulosic materials which msy be derived fr~m both natural and synthetic sources. Also included are sheet-like masses ~-and molded prcduct~ prepared from combinatio~ of cellulosic ~nd non-cellulo~lc materials derived from synthetics such as polyamide, polyester and polyacrylic resin fibers as well as from mineral fiber~ ~uch as a~bestos and glass.
Papsr and paperboard are oft~n 8ized with various msterials for the purpose of increasing their reslstance to water a~ well as to other type~ of aqueous solutlons. mese materlals are referred ~o 88 sizes or sixing and they may be introduced during the sctual paper making operation wherein the proce~s 1~ known as internal or en~ine ~izing. Or, on ; ~ - the other hand, they may be applied to the surface of the I~
fini8h~d web or sheet ~n whlch case th~ proce~s i8 known 8~ '.

. , . I
., 1~ 6 8 0 5 5 ....
external or su~f~ce 8 ~z~ng, Vsriou~ water-repellane materials ilave been utilized as siz~ng ~ent~. These include r~sin, mixtures of ro~in with w~x~s, wax emul~ons, ketene d~mer emul~Lon3, fluoroc~rbons, fatty scid complexe3 of chromlum or aluminum chlorides, long chain thermopl~tic copolymers, as well ~8 some tkermo~etting co~den6stion type resins. Although all oi the~e materialQ are effectlve under certain cond~tion~, their use i8 nonetheless $ub~ect to one or mor~ limitations.
m us, for ex~mple, in the ca~e of ~osin, although the lsttcr ~8 re'atively low in cost and readily svaIlable, Lt h~s poor resi~tancQ to alkaline solut~on~ and cannot be used for the sizing of neutr&l or alkaline pu~p~. It is inoperab}e w~th the lstter ~ince-it must be ordinar~ly u~ed in combin~tion with alum or an acidic sluminum ion donor, which i8 present for f the purpose of precipitating and s~tting the ~odium ros~nate, i.e. the rosin 80ap, onto the fibers. The use of alum or !~
this purpose i8, however, precluded under neutral or alkalinP
conditions. Thi8 is 8 definlte d~s~dvantage s~nce the paper produced from neutral and alkallne pulp hss been ~ound to have hi8her strength, greater ~tab~lit~ snd superior aging characte,-18tlcs in compsrison with the paper prepared from acidic ~ulp.
Al80, the Internal use of alknline pigments such a8 c81cium carbonsts is precluded. This s~me lLmitation also applieQ
to the use of most wax emulsions which can~ot be used on the ~Iksline side 8ince they are u8ually co~bined with ~mall quantitie~ of alum for the purpo8e of breaking the emulsion6.
On the other hand, certain ~izing agentR-will not tolexate ' sppreciable quantities of alum or high ~cidic conditions. In 80me c~se~, it may ~e desirable ~r necessary to UQe alum for - ftller retention purpo~e~, for increaQing ~heet drainage, or to ret~in or set cond ~ sation resin add~t~ves, etc. Certs~

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1068'~)55 sizing agents c~nn~t be adequately retalned ln the sheet during shee~ for~at~on and, consequently, are llmlted only to external or Qurface appllcatLon~.
In addlt~on to the abov~ described pH limLtations, the water resistance or water holdout which i8 attainable wlth many of the heretofore employed sizlng agents i8 ofter.
1nsde~uate for many appllc~tlons whlch may requlre paper or paperboard displaying ~n exception~lly high degree of water resistanc~. Moreover, many of these sizing agents have been found to be incompatible with the pigme~t~, filler~, or other - ~ngredients which often are ~dded to paper. A further disadvant~ge of ~ome 61~1ng agents 18 that a considerable degree of heat curing i8 required to devalop full effectlve- -~
ness. Thus, in using the3e materials, full effectiveness and full sizing value may not be obtained immediately after formation and drying of the paper web. `
The use o slzing agents which are substituted cycllc ~ .
dicarboxylic acid anhydrides ha3 been descrlbed ln U. S. Patent ~-No. 3J102,064 patented August 27, 1963 to Wurzburg and Mazzarells and as~igned to the ~ssi8nees of the present application. In that patent the slzing agents correspond to the following structural formula~

O '~
'l . . i, ~C , .. ,, , .. , ,. .. ". ~ :,' .
0 ~R- R~
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o :
wherein R represents a dimethylene or trimethylene radlcal end wherein R' is a hydrophobic group containing more than 5 c~rbon atoms which may b2 seleceed from the cl2ss consisting \ ~ ~

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of alkyl, alkenyl, aralkyl or aral~;~n;l groups. Sub~tituted cyclic dicsrboxylic acid anhydrides falling within the above de~cribad formula are the sub~ituted succinic and glutarlc ~cld anhydr~des.
The use of the~e prior art rea~ents as 8ize8 for paper and paperboard has been ~ound to reQult in the preparation of products which display an unusually high degree of w~ter res~tance. The 6uccessful use of these sizing agen~s i8 not restricted to any particular pH range whlch thus 8110w8 for thelr utilization in ~he treatment of :~
neutral and alkaline pulp as well as ac~dic pulp.
The sizing agents described in the aforementioned pa~ent are mainly prepared from linear olef~ns where the double bond i8 in thé 1,2 or 3-position, or from short chained branched olefins such as triisobutylene. U8C of the above ~ -:
classes of olèfins leads to sizing a~ents where the R' group i8 either linesr or linear with multiple methyl or ~thyl groups pend~nt from the linear chain. Alternatively, R' ~18 linear with a pendant methyl, ethyl or propyl group (which group msy be saturated or un~atursted) attached to the c~rbon atom which itself i8 attached,to the cyclic ~nhydride :~
moiety. Among examples of 6izing agent~ described in the ~forementioned patent ~re included iso-octadecenyl 6uccinic ~cid anhydride, n-hexadecenyl ~uccinic scid anhydride, ' dodecenyl succinic acid ~nhydride, tril~obutenyl 8uccinic ' ~cLd ~nhydride, etc. '`
It ha~ now been ,found that when the cyclic dicarboxylic acid ~nhydride sLzing agent is prepsred from a vinylidene olefin corre~ponding to the following general structure .
', .
- 4 - ' ~ ;,`, - '~ .

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6 8 ~ 5 5 CH2 ~x ~2C~ C\
CH2 y wherein Rx and Ry are ~lkyl radicals containing at least 5 carbon atoms in each rad~cal, th~ refiultant sizLr.g agens `~
~ far more effectlve (i.e. de~red siz~ng prope.rties are schieved at substantially lower concentrations) than th~
sizing agen~s of the prlor srt wh~ch ~re prepared employing ;-;. olefins having the double bond in the 1,~.2, or 3- po~Ltion ;
or the short chalned branched olefins. --~
The vinylidene ole~lns such as defined sbove ~re prepared by dimer~zlng alpha olefins 88 is known to those ., .
skllled in the art.
The slzing agents of the present invention ~;~
correspond to the following structural formula H
C - C - CH2 - C - CH2 x C - CH2 , -~ Ry , ~berein Rx and Ry are as defined above snd are inter-changeable. ~ixtures of t~e vinylidene olefins may be used - ln preparlng the 8izln~ agent~ ~nd, of course, mlxtures of the sbove ~izing agent8 msy also be employed in the proc~s of thi~ invention. _ - Examples of 8izing agent8 typical of thi8 lnventlon include size8 preparet by the resction of maleic acit anhy-tride with vlnylidene olefin8 such as 2-n-hexyl-1-octene,

2-n-octyl-1-dodecene, 2-n-octyl-1-decene, 2-n-dotecyl-1-octene, 2-n-octyl-1-octene, 2-n-octyl-1-nonene, 2-n-hexyl- -- decenç snd 2-n-heptyl-1-octene. The sizing agents con~em-plated herein are non-polymeric.
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11~16805S

The preferred lnylidene olefins will contain 14 ~o 22 carbon atomq but olefins having more than 22 carbon atoms may ~lso be used.
The re~ction of cert~in of these olef~n8 with maleic anhydride will result in producing mixtures of slzing flgents.
Where lar~e ~c~le uaes of ct ~mercially supplied oleflns ~re involved, it 18 noted ttlat such oleflns ar~ very often mixtures o~ related oleflns with one or ~ore ~pecies belng predomlnant. These olefin m~xtures when reacted wlth the ~nhydride will aleo result in produclng mixture~ of ~lzing agents. For these rea6cn6 ehe novel 8iZirlg agents sre not defined herelnafter by their chemlcal structures but rather ~re referred to and identified as a reaction product of malelc ~ci.d anhydride with a ~pecified olefin which Ltself may pos8ibly be a mixture. ~h~ reaction of maleic acid anhydride with olefins is well known to those sk~lled in the art.
The novel sizing agent~ dLsplsy 811 of the features and advantages of the cited prior art sizing agents. Moreover, the sizing agents of this Lnvention i.mpart to paper ~ized therewith ~ particularly good reslstance to acidic llquids such ~ acid inks, citrlc scid, lactic acid etc. 88 compared to paper slzed with the sizing agents of the cited prior art.
In addition to the properties alre~dy ment~oned, these sizing ~sgent~ may ~180 be used Ln combin2tion with slum a1 well a8 with any of the pigment~, filler8, ~nd other ingredients which may be added to paper. ~he sizing agents of the present invention may also be u~ed in con~unction with other sizing ~gent8 80 a8 to obtain additive sizlng effects. A ~till further advantage is that they do not detract from the ~trength of the paper ~nd when uset with certain ad~uncts~ -will, in fact, increa8e the 8trength of the flnlshed sheets.
Only mlld drying or curing condltion~ are required to develop ..~ -- 6 - i ;:

.

.,. .. . -1 0 6 8 ~5 5 fl~ll 3 ~ z f n~ va lue .
The actual use of ~he~e ~Izin~ agents in the msnufacture of papes iB subject to a n~ber o~ vas~a~ion~
in technlque any of which m~y be furthes modl~ied ln llght :;
of the spec~fic requlxements of the practit~oner. It i~
import~nt to emphasize, howeYer, that with all o~ these :
procedures, ~ t 19 most essentLal to achleve a uniform disper~al of t~e 6Lzlng agent throughout th~ ~lber 61urry~
thereby RecessItating that lts ~ddltion to,the pulp be accompanled wLth prolonged and vigorou~ ~itatlon. Unlform~
dl~pera~l may al80 be obta~ned by adding ~he sizing agent -~
l~n n ully dlspersed orm such a9 ~n emulslon; orJ by the coaddltion of chemical dlspersing agents to th~ 1ber ~lurry. ~:
Another important factor ln the effectlve utlllz~tion of the ~izing ~gents of this Inventlon InvoLves their use in conJunctlon with a materlal whlch is either cstionic in nature or 1~, on the other hand, capsble o ionlz~ng or di~ociatlng in ~uch a manner a~ to produce one or more c~ions or other . positlvely charged n~eties. These cs~ionic agent~, 88 they wlll be herelnafter re~erred to, have-been found use~ul as 8 mean~ for aldlng in the retent~on of sl~ln~ ngents hereln - as well a~ ~or bringin~ the latter into clo~e proxlmity to thc pulp ~ibers. Among ~he materials which may be employed a~ catlonlc a,ge~lt~ ln the proce~l~ hereLn one ~y LL~t ~
lumlnum chloride, lonR ch~n fstty ~mLnes, sodium ~lumLnate, subseltuted polyacrylamLde, chromlc ~u1fste, anLmal gluc, cstion~c the~ettLng rcslns and poly~mide polymer~. Of partlcul~r lnterest for use as catlonlc agent~ are varLous c~tionic 8tarch derivatlves l~cludl~g priQasy, ~econtary, tertIary or qu~ternary smlne ~tarch derivatlve~ and other .
cstionic nitrogen substituted sta~ch derlvstLve~, ~8 wel~
~8 cseIonic sulfonLum and phosphonium ~ta~r~h derivatives.
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- . : .. - :, :

Such derlvative~ may be prep~red from all types of starche~
includLng corn, tapioca, potato, waxy m~ize, wheat and rlce.
Moreover, they may be in their original granule form or they may be~converted to pregelatinized, cold water ~oluble products.
Any of the ~bove noted catlonic agent~ msy ~e sdded to the stock, i.e. the pulp slurry, either prior to, along w~th or sfter the additlon of the siz~ng agent. However, ln order to schieve maximum distrlbution, it is pre~erable that lQ the cationlc agent be added elther ~ub~eq~ent to or ~n direct combination with the sizing sgent. The actual addit~on to the ~tock of either the catlonic agent or the sizing agent may take place at sny point in the paper making process prior to the ultimate converfiion of the wet pulp into a dry web or sheet. Thus, for ex~mple, these sizing agents -~
may be added to the pulp while the latter i8 ln thc headbox, ~eaterJ hydropulper or stock che~t.
In order tu obtain good ~izing, ~t i9 deslrable that the sizing agent~ be unifonmly disper~ed throughout the fiber slurry ln 8s small a partlcle ~ize as i~ possible to obtain. One method for accomplishing thLs i8 to emulsify the slzing agen~ prior to its addition to ths stock utilizing either mechanic~l means, such as high speed sgitators, mechanical homogenizers, or by the addition of 8 suitable emulsifying a8~nt. Where possible, it is highly de81rable to employ the c~tionic agent 8B the emulsifier and this procedure ~9 particularly 8ucce88ful wherQ cationLc ~t~rch derivatives are utilized. Among the applicable : noA-cstlonic emulsifiers which may be used aB emul8ifying ~8ents ~or the sizing agents, one may list such hydrocolloid~ ~
~8 ordinary starches, non-cationic st~rch derivatives, ~;
; dextrines, carboxymethyl cellulose, gum arabic, gelatin, and ; ~
. . . - ;

'' : ' ' . ,' . ,, ' ~ ' ': : .
":. .. . ' , ' - ' ' ' .' : ' ' .. .

. .
polyvinyl alcohol a~ well as various surfactants. Examples of such surfactants include polyoxyethylene sorbit~n trioleate, polyoxyethylene so.bitol hex~oleate, polyoxyethylene sorbitol laurate, snd polyoxyethyl~ne sorbitol oleate-laurate.
When such noncationic emulslfiers are used, it Ls often desirable to ~eparately add 8 cationLc agent to the pulp slurry after the addition to the latter of the emu~sified ~izing agent. In preparing these emul6ions with the use of an emulsifier, the lutter i8 usually fir~t dispersqd in wates and the sizing ~gent i8 then introduced along with vlgorou~
~gitation. ;
Further improvements in the water resistance of the psper prepared with these novel slzing agents may be obtained by curing the resulting webs, sheet~ or molded products. This curing process involves hesting the paper at temperatures in the rsnge of from 80 to 150C. for periods of from 1 to 60 minute~. However, It should agsin be noted that post curing is not essential to the succe~sful operation of this invention.
m e ~iz~ng agents of this invention, may, of course, be successfully utilized for the sizing of paper prepared from all types of both cellulosic and combinations of cellulosic - with non-cellulosic fiber8. The cellulosic fibers whlch may be used include bleached ant unbleschet sulfate (kraft), bleached and unble~ched sulite, bleached ant unbleached Joda, neutrs~ sulfite, semi-chemlcal chemigroundwood, ground wood, and any combin~tion of these fibers. m ese designations refer to wood pulp flbers which have been prepared by means o ~ variety of processes which are used in the pulp and psper ~ntu8try. In addition, ~ynthetic fibers of the viscose rayon or regenerated cellulo~e type csn ~180 be u~ed. , - .~ ,,, .. .
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All types of pigments and flllers may be added to the paper which is to be sized with the novel sizing agents of thls Lnvention. Such material~ lnclude clay, talc, tltanium dioxlde, c~lcium carbonat~, calcium ~ul~te, and diatomaceous earths. Other ~dditlves, includ~ng alum, as well a8 oeher sizing ~gents, can also be used wlth t.~ese ~zing agen~
With respect to proportion~, the sizing agents may be employed in ~mounts ranging from about 0.05 to about .10 3.0% of the dry weight of the pulp in th~ finished she¢t or web. While amounts in excess of 3% may be used, the benefits of increased s~zing prop~rties are usually not economically ~ustified. Within ~he mentioned range the preclse smount of ~ize which is to be used will depend for the mo~t part upon the type of pulp which is being utilized, the specific operating conditions, as well ~ the partlcular ent use for which the paper is destlned. Thu8, for example, -~
psper which will require good water re~istance or ink holdout will necessitate the use of a higher concentr~tion of sizing agent th~n paper which will be used in applications where ~;
excessive 6izing 18 ~ot needed. The same factor8 also - apply in relatlon to the amount of cstionic agent which may be u8ed in conJunction with these sizing agents. The practitioner will be able to use these materials in any concentration which i8 found to be applicable to hi~ ~pecific operating ~onditions. However, under ordinary circumstances a range or from 0.5 to 2.0 parts by weight of cationic agent per 1.0 part of sizing agent i8 usually adequate. It csn be noted that the catlonic agent is present in a quantity of at lea8t 0.025% of the dry weight of the pulp in the paper.
The u8e of the sizing agents of thLs in~ention ` provide8 a degree of acid water resistancQ to paper which i~

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, . .. ~ ,. -~: ~ .. . . - - .

: . : ; .. -- - . .. . ~ . , .
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1~ 6 8 0 5 5 substantLally hlg~er thsn is obtalned by ~l~ing ~gent~ of the prlor art and paztlculsrly those of U. S. Patent

3,102,064.
The ollowln~ examples wlll further lllustrate the embodiment of the described invention. In the~e examples all parts giverl are by welght unless o~herwLae noted.

- Example I
.
' This example illustrat~s the use of a sizi~g agent representative of the sizlng agent~ of th1s ~nvention ln the iorm of an aqueous emulsion where~n the emulsifiQr used i8 a ~, tertiary amine cationic starch derivative. The water reslstance of the resulting paper i8 compared with that of paper which had been sized with lso-octadecenyl succinLc acid anhydride, a size typical o~ those described in U. S.
Patent No. 3,102,064.
An ~qUeOU8 emulsion of B sizlng ~gent comprising the reactlon product of maleic snhydride and a vinylidene olefin hsving 20 c~rbon stoms was prepared by firet cooking 10 parts of the betadiethyl aminoethyi ether of corn starch (who8e preparatlon i~ described in Example I of U. S. Patent No. 2,813,093) Ln 90 parts of water which wa~ heated on a boilLng water bath. Ths disperslon of the catLonic starch derivatlve ~after being cooked for 20 minutes was cooled to room temperature and transerred to a high speed sgitator whereupon 5 parts of the maleic anhydride-vinylLdene ole in ~izing agent were slowly added to the agitated disperslon.
-A~ltat~on was continued for about 3 mlnutes and the resulting emul~ion was then diluted with water to eq~al a total of ; 30 l,000 parts (0.5~ solids).
Calculated amounts of this stock emuls~on were ~ , , :

. , . - , - ~ .

.

: , added (dlluted with water~ to aqueou~ slurrles o~ bleached ~ulfate pulp hav~ng a freeness of 500, a consistency of 0.5%
and a pH o 8~0ut 7.6 ~0 that th~ s~ze would be pse~ent in concentrations of 0.20 and 0.40Z by weight of the dry pulp.
Sheets were formed and dried in accordance wlth TAPPI
standards, the ba~is weight of these sheets being SS lbs/ream (24" x 36" - 500 sheets). By means of the same procedure, comparable sheets ware made wich cont~ined ldentical amounts of iso-octadecenyl 6uccinic anhydride (abbreviated IODSA) emulsified ~ith the cationic ~tarch derivative described above.
Whcre the sheet~ were cured, the curing was ef~acted by the use of hot circulatLng air oven~, one hour at 105C.
In comparing the water resistance of sheet~ prepared using the maleic anhydride-vinylidene olefln sizing agent with sheets prepared with IODSA, u~e was made of an acit ink penetration te~t.
The acid ink penetration test is a comparlson test where$n a swatch of p~per is floated in a dish of acld lnk (pH 1.5) at 100F. and the time (measured in seconds) required for the ink to penetrate through the paper to reach an end-point where about 507. of the paper i8 colored iB noted.
Tbe following table presents data on the varLous paper shee~ which were compared in the described testing procedure. The ~iz~ng agent prepared from the reaction product of maleic anhydride and the vinylidene olefin i8 designated ~A/VO.

. .. - . . .
. . , ,; .
.
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- 12 - ~ :

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~able I
Sheet Sizing 7. by weight Acid I~k Penetration No. Agent of dry pulp (tlme in seconds) Uncured Cured MA/~!O 0. 2 60 SO
2 MAfVO 0.4 14~ 270 ~
3 IODSA 0.2 40 48 -. 4 IODSA 0.4 105 i245 In order to further evsluate the performsnce of 1~ the new vinylidene olefin sizing agent~, paper sheets were prepared employing ~hé emuls1fied sizing agent u6ing the ~le~ched ~oft wood pulp described above but with the p~ of the pulp lowered to 6.0 wlth alum. For compsrlaon purposes paper ~hee~ utLlizing IODSA were alsc preparet employing the identical procedure. On evaluation o~ the s~eets ln ; the acid Ln~ penetration test, the following re8ults were obtained. .
Table II
. .
Sheet Slzing % by weight Acid Ink Penetrstion No.Agent of dry pulp ~ti~e ln seconds) qn . . Uncured Cured ,. v . .
1MA/VO 0.2 180 240 2. MA~VO 0.4 290 . 430 3IODSA 0~2 120 150 4IODSA 0.4 150 205 ~ . ` The above data clearly 8how th~t the paper 8ized - with the new vlnyliden~ ole~ln ~lzlng agent dlsplsyed ~- : substantlally incre~sed re~lstance to ~cld penetratlo~ .:
- .
.
: - 13 .

. - . ; ' ' - :
. .
. . , .

measured by the acid ink penetra~ion test as compared ~o paper sized with IODSA.

Example II
~ hi~ exa~ple illustrates ~he use of anothes maleic anhydride-vinylidene olefln sizing agent representative of thLs Lnvention.
- In thls example the sizing agent was prep~red from ., maleic anhydride ~nd a mlxture of vLnylidene olefins con~ain-ing 16) 18 and 20 carbon atoms. The olefin mixture wa6 co~pri~ed of sbout 25% of C16 olefin, 25~ of C20 olefin and 50% of C18 olefin. An aqueous emul~on of the slzing agent was prepared by means of the procedure described Ln Example I
wherein the tertiary amine catlonic 6tarch derivstive described therein was ag~in used as the emulsifLer.
C~lculated amounts of the emulsion were added to ~epsrate batche6 of bleached sulfate pulp having a freenes~ of 500 and a consistency of 0.5Z. 80 as to result in a size concen~
tration of 0.2 and 0.4Z. by weight of dry pulp. The pH of the pulp slurrie~ was 7.6 snd 6.0 (adJu~ted with alum).
Sheets were formed and dried in accordance with TAPPI
8tandards, the b~sLs weight of these sheets being 55 lbs/ream.
By means of the same procedureJ compsrable sheet8 were made for compsrison purpo~es containing comparsble concentr~tlon8 of IODSA. Where the sheet8 were cur¢d, the curing wa8 effected by use of hot air for one hour at 105C, All ~heets were te8ted by the acid Lnk penetration test described ~n Example I with the testin8 results obtained being 8ummsrLzed in Tabl¢ III.
. ~ ~
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Table III
Sheet Si~ing 7. by weight P~lp Acid Ink Pe~etrRtion No, Agent of dry pulp pH (time ln seconds) Uncured Cured ~ MA/VO 0.2 7.6 32 190 2 ~/VO 0.4 7.~ 53 600+
3 IODSA 0.2 7.6 40 ¦ 48

4 IODSA 0.4 7.6 38 85 MA/VO O.2 6.0 110 135 6 MA/VO 0.4 - 6.0 190 360 7 IODSA 0.2 6.0 90 120 8 IODSA 0.4 6.0 125 160 . : -, The above results indicate tbat paper sized with the novel male~c anhydride-vinylidene olefin size have an . acid ink resi~tance ge~erally superior to paper sized with IODSA.
While the novel sizing agents hereln have been ~ ~:
Iimited to those prepared by the reaction of male~c acid ~nhydrLde with vinylidene olefins, ~lzing agents may al80 be prepared using a homologous anhydride, ~lutaconic acid, together with the identical oleins and be expec~ed to provide similarly ef~ective sizing properties to paper.
In summsry, the invention i8 seen to provide the prsctitioner with novel ~izing agents capable of providing psper products which are characterlzed by their high degree of acidic wster resistAnce re~ative to 8~milsr sizlng ~gents o~ the prior srt. Variations may be made ~n proportlon~, :
procedure3 and materials without d~parting from the scope of ~his invention. .

- 15 ~
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Claims (10)

The embodiments of the invention in which an exclu-sive property or privilege is claimed or defined as follows:

1. The method of sizing paper which comprises the step of intimately dispersing within the wet pulp, prior to the ultimate conversion of said pulp into a dry web, a sizing agent which comprises the non-polymeric reaction product of maleic acid anhydride with a vinylidene olefin corresponding to wherein Rx and Ry are alkyl radicals containing at least 5 carbon atoms in each radical.

2. The method of Claim 1 in which the sizing agent is in the form of an aqueous emulsion.

3. The method of Claim 1 including the additional step of intimately dispersing within the wet pulp, prior to the ultimate conversion of said pulp into a dry web, in addition to said sizing agent, at least 0. 025%, based on the weight of the dry pulp, of a cationic agent.

4. The method of Claim 3 in which said cationic agent is selected from the group consisting of alum, aluminum chloride, long chain fatty amines, substituted polyacrylamide, animal glue, polyamide polymers, cationic resins and cationic starch derivatives.

5. The method of Claim 1 in which said sizing agent has been emulsified with a surfactant prior to its dispersion within the wet pulp.

6. The method of Claim 1 in which said sizing agent is the reaction product of maleic acid anhydride with a mixture of vinylidene olefins of 16-20 carbon atoms.

7. A paper product having intimately dispersed within the wet pulp thereof, prior to its conversion into a dry web, a sizing agent which comprises the non-polymeric reaction product of maleic acid anhydride with a vinylidene olefin corresponding to wherein Rx and Ry are alkyl radicals containing at least 5 carbon atoms in each radical.

8. The paper product of Claim 7 having intimately dispersed within the wet pulp thereof, prior to its conversion into a dry web, in addition to said sizing agent, at least 0.025%, based on the weight of the dry pulp, of a cationic agent.

9. The paper product of Claim 8 in which said cationic agent is selected from the group consisting of alum, aluminum chloride, long chain fatty amines, substituted polyacrylamide, animal glue, polyamide polymers, cationic resins and cationic starch derivatives.

10. The paper product of Claim 7 wherein said sizing agent is the reaction product of maleic acid anhydride with a mixture of vinylidene olefins of 16-20 carbon atoms.