CA1057009A - Method of making a novel starch derivative and the product produced thereby - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The use in the manufacture of paper and novel addi-tives comprising derivatives of starches having particular levels of water fluidity and which contain controlled pro-portions of cationogenic or cationic substituent groups as well as sulfo-succinate groups. The resulting paper contain-ing the latter additives is characterized by improved reten-tion of pigments and increased strength.

Description

1~570()~

Our invention relates to a method for making paper, and to the improved paper thus obtained. More specifically, it is our object to provide an additive which may be incor-porated with the paper stock durin~ the manufacture of paper to thereby improve pigment retention and add greater strength as well as other desirable properties.
Our invention comprises the addition to paper stock of novel starch products co~prising starch derivatives con-tainin~ controlled proportions of cationogenic or cationic su~stituent groups as well as sulfo-succinate grou?s.
~ s used herein, the term "paper" includes sheet-like masses and molded products ~lade from fibrous cellulosic materials~ which may be derived from natural sources as well as from synthetics such as polyamides, polyesters and poly-acrylic resins, as well as from mineral fibers such as as-bestos and glass. Also included are papers made ~rom combi-nations of cellulosic and synthetic materials. Paperboard is, o course, also included, within the broad term "paper".
It has been known to add various materials, includ-ing starch, to the pulp, or stock, durinp, the papermakin,~,process, prior to the formation of the sheet. The purpose of such additives has been mainly to promote a Eiber bondin~
and to Eacilitate the ormation of strongjer paper.
Fllrthermore, in the case o~ those papers ~hich con-tain added pigments, ~such for example as titanium dioxide, it llas been known to add materials to the pulp, or stock, for the specific purpose of retaining a ~,reater proportion of such pi~nents in the paper (rather than have them drain off in the water that is re~noved during the forrnation of the sheet). Such addit~ves are often referred to as "pi~nent retention agents".
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il~S7~)09 One of thc serious problems heretofore encountered in paper manufacture has been that additives employed for binding and strengthening tl.le paper had insufficient effect in improvin~ pig,llent retention, or in man~ cases actually de-creasing the amount of pi~ment retained by the paper. Simi-larly, those additives w~ich were most effective as pigment retention a~ents had no effect in strengthening the ultimate paper sheet, or in some cases actually drastically weakened it.
The aminoalkyl starch ethers described in U.S. Patent o. 2,813,093 and em?loyed in the paperTnaking process of U.S.
Patent No. 2,935,436 have brou~ht abou~ improvements in both paper strength and pigment retention. However, the search for greater improvements has continued, with the particular objective of providing an additive that would be e~fective at a low p~ ran~,e in the presence of aluminum salts, regardless of the hardness of the water which is employed in the pulp and in cooking the starch.
It has been proposed to use starch phosphates as pigment retention agents, and their effectiveness has been noticeable with paper stock containing low to moderate con-centrations of alum.
At higher alum concentrations, however, the effec-tiveness of starch phosphates declines, due to reasons not readily understood. Possibly this is because the phosphate groups function as wea~ acids, which are incapable of provid-ing desired pigment retention and of increasing paper strength in the presence of alum concentrations greater than 4 per cent, by weight, oE the dry pulp. Thus, starch phosphates (e.g., di- and tri- alkyl aminoalkyl starch phosphates), like other anionic starch derivatives of the prior art which are effective at lower concentrations of alum, are inferior 1057~09 at higher alum concentrations when compared to the novel starch products of this invention.
At low alum concentrations, some pigment retention performance improvements can be obtained by introducing carboxyl groups such as car- t boxymethyl groups or half estèr groups (e.g., succinate groups or maleate groups) in starch amine alkyl ethers or native starches.
However, the search for greater improvements has continued, with the particular objective of providing an additive that would be effective at the higher alum concentrations often found in the paper industry, 10 particularly in connection with the increasing utilization of recycled paper.
This, it is the prime object of this invention to provide novel starch products which are useful in the manufacturing of paper having high alum acidity.
It is a further object of this invention to provide an additive useful in the manufacturing of paper, which may be added to the pulp or stock at any time during the paper-making process, prior to the formation of the sheet, and is capable of improving both the pigment retention and the strength of the paper.
Various other objects and advantages of this invention will become apparent from the following description thereof.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides for a paper contain-ing pigment and alum and having dispersed therein as a pigment retention aid a starch derivative of an ungelatinized starch base having a water fluidity between 4 and 40, said starch derivative containing chemically introduced sulfosuccinate groups and cationogenic or cationic nitrogen containing ether-linked substituent groups selected from the group consisting of primary amine, secondary amine, tertiary amine and quaternary ammonium groups wherein the degree of substitution of said cationogenic or cationic nitrogen containing substituent groups in said starch derivative ~ -3-.

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~ 057QO9 is about 0.005 to 1.50, and the degree of substitution of said sulfo-succinate groups is at least 0.008, said paper being prepared from a papermaking stock containing from about 0.05 to 2.~% of said starch derivative by weight of dry pulp.
According to another aspect the present invention provides for, in a method for making paper containing pigment and alum, the step which comprises adding as a pigment retention aid to the stock containing more than 4% alum by weight of dry pulp, at any stage prior to forming a web, a starch derivative of an ungelatinized starch base having a water fluidity between 4 and 40, said starch derivative containing chemically introduced sulfo-succinate groups and cationogenic or cationic nitrogen containing ether-linked substituent groups selected from the group consisting of primàry amine, secondary amine, tertiary amine and quaternary ammonium groups wherein the degree of substitution of said cationogenic or cationic nitrogen containing substituent groups in said starch derivative is about 0.005 to about 1.50, and the degree of substitution of said sulfo-succinate groups is at least 0.008, said paper being prepared from a paper making stock containing from about 0.05 to 2.0% of said starch derivative by weight of dry pulp.
More particularly, we have now discovered that the addition of a novel starch derivative, hereinafter described, to the pulp at any stage prior to the formation of the paper sheet, results in a remarkable improvement in pigment retention, together with a concomitant increase in paper strength at alum concentrations -3a-.'.

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: '. , 5 7 ~ O 9 above 4 per cent, by ~eight, of the dry pulp.
The novel additives in our invention are starch de-rivatives o~ ungelatinized starch bases havin~ a water fluid-ity between about 4 and about ~0, the starc~l derivatives con-tainin~r, a controlled amount of cationo~enic or cationic arnino-alkyl ether ~roups or quaternary ammonium ether ~roups to-~ether with a controlled amount of sulfo-succinate groups. In addition to the foregoin~r nitro~ren/cationic ~,roups and sulfo-succinate ~,roups, the additives o~ our invention may also con-tain phosphate ~roups as described hereinafter, hydroxypropylgroups, acetate ~roups or other substituent groups in amounts perrnitting granular starch character and increasing solubility.
~ s the cationogenic or cationic substituent in our starch additive, we prefer a tertiary amine ether or quaternary ammonium ether group. ~Iowever, other cationo~enic or cationic groups are operable, as for example, primary and secondary amine ~roups, sulfonium and phosphonium groups attached by ether or ester linkages.
The preparation of the aminoalkyl ethers of starch, wherein the starch derivative contains tertiary amine groups, is described in U.S. Patent No. 2,813,093. Similarly, sulfonium and phosphonium derivatives of starch are described in U.S. Patent Nos. 2.989,520 and 3,077,469, respectively.
It is known that quaternary ammonium ~roups may be introduced into the starch molecule by suitable treatment of the tert~ary aminoalkyl ether of starch, as ~escribed, for example, in U.S. 2,813,093 or quaternary groups rnay be intro-duced directly into the starch molecule as, for example, by treatment with the reaction product of an epihalohydrin and a tertiary arnine or tertiary amine salt.
Also, as stated, the starch derivatives to be suit-: ~ - . , - . - . . .. :

~ 57 ~ V 9 able as an additive to the paDer pulp in the process o our in-vention, must contain sulfo-succinate ester ~roups. It should be mentioned that, for the purpose of our invention, the sulfo-succination of the starch, i.e., the chemical introduc-tion of the sulfo-succinate groups to the anhydroglucose units, is to be carried out aEter the starch has been modified with the nitro~,en containing cationogenic or cationic ~roups and, ~referably, after it has been converted.
Various techniques for sulfo-succinating the starch base are well kno~m to those skilled in the art. For exaTnple, U.S. Patent No. 2,825,727 discloses a method or treating ethylenically unsaturated starch derivatives prepared accord-in~J to the method described in U.S. Patent Mos. 2,461,139 and

2,668,156 with bisulfite.

D~TAILED DESCRIPTI~
OF THE PR~FEP~P~ED EM~ODI~NTS
_ _ _ _ _ _ . _ _ The starch bases suitable for the process of our invention must be in the intact granular ~orm and must have or be converted to a water fluidity o-E at least 4 but no greater than 40. Hence, among the suitable starch bases are included those in their ungelatinized form, which r,ay be de-rived from any plant source such as corn, rice, tapioca, sago, waxy maize, sorghum, potato, sweet potato, wheat, high amylose corn or the like. The particular starch chosen may be converted to its Eluidity or thin-boiling form at any sta~e prior to sulfo-succination, using any suitable method of de~,radation such as thermal treatment in the presence of sodium phosphate with an amylase on granular starch, or mild oxidative conversion, or mild acid hydrolysis or controlled enzyme conversion. Therefore, since the necessary conversion of the starch to a water 1uidity within the prescribed range may be carried out before or after modification with the cationic groups, the selection of the sequence prior to sulfo-succination is left to the practitioner. We have also found that the phosphate ester ,~,roups, such as found in potato starch, or the introduction oE such c-!roups into corn starch by heat reacting with phosphate salts rnake the starch suitable for introduction of the sulfo-succinate ~roups without convert-ing. The de~ree of substitution (D.S.) of the phosphate groups may ran~e from 0.003 to 0.01.
We have Eound that the starch derivatives suitable for use in the process of this invention should be substituted with cationoF,enic/cationic ?,rou~s to such an extent that their degree of substitution (D.S.), i.e. the avera~,e number of cationo,~,enic/cationic ~,rou?s per anhydro~lucose unit of the starch molecule ran~es ~rom about 0.005 to 1.50, ~,enerally at least 0.01, and preferably Erom about 0.02 to about 0.04. At higher D..5. ran~,es, it is necessary to protect the c~ranule structure by means known to those skilled in the art.
Any of the foregoing types of substituent ~,roups may be utilized se~arately or in combination with any of the other useful nitrogen containinC, ~,roups or with sulfoniwn or phosphonium r,roups, so long as the total D.S. does not exceed about 1.50.
The quantity oE the sulfo-succinate ester ~roups chemically bound to the starch molecule, an~ rnore specifically to the anhydro~lucose unit, is important ~ecause it affects the pi~rnent retention in presence of aluln concentrations hi~her tllan about 4,'. Althou~,h the presence o~ very small amounts o:E the sulEo-succinate ester ,roups ~Jill demonstrate improvements (e.~,., 0.008 moles per Inole of anhydro~lucose unit), 0.02 o~ more is the preferred amount.

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Since the ~urpose or this invention is not a balanced performance at various plls, but im?roved performance in the presence of high concentrations of alum, the ratio of the anionic groups to cationo~,enic or cationic groups is of lesser importance. ~lowever, thè ~resence of cationogenic or cationic groups will noticeably im~rove retention and stren~,th at lower concentrations of alum.
As previously r,lentioned, it is also possible to em-ploy in our process starch derivatives containin~; other sub-stituent groups beside the required cationogenic/cationicand sulfo-succinate groups.
The technique for phosphorylating a starch base is known to those skilled in the art. Thus, U.S. Patent ~los.
2,824,870, 2,884,412 and 2,961,440 disclose various phosphory-lation techniques consistin~,, essentially, of heat reacting starch impre ~ated with a phosphate salt of an alkali metal, within a prescribed pH range. For the purpose of our inven-tion, the phosphorylations are limited to reactions o~ starch with any phosphorylatin~, a~,ent yielding orthophosphate mono-ester ~roups, i.e. mono-starch phosphates.
A representative method for carryin~ out a suitable phosphorylation would be similar to that described in as-signee's U.~. Patent No. 3,459,632.
The preparations of the phosphonium and sulfonium starch derivatives are described in U.~. Patent ~os. 3,~77,469 and 2,989,520, respectively.
Obviously, the practitioner will reco~nize that various other optional cationo~enic or cationic substituents may similarly be linked to a com~on anhydroglucose unit, it being remembered that in carryin~ out our process, not only is it imperative that the starch base be converted to a ~O ~7 ~ O 9 water fluidity between 4 and 4n or naturally contain phosphate groups, but the synert~istic cornbination of the aminoalkyl ether or quaternary ammonium. crrou~s and the sul~o-succinate crroups must be present within the ?rescribed range.
Other suitable cationo,~r,enic or cationic starch de-rivatives wi]l be apparent to the practitioner, it bein,~, re-membered that our process ~nay emnloy any starch derivative ~7hich contains a cationic (i.e. elec~rically positive char~red) moiety in the starch molecule.
m e herein describecl starch derivatives are used mai.nly as beater additives, althou~h their addition may occur at any point in the pa~er-makin~ ~rocess prior to the ultimate conversion of the wet pul~ into a dry web or sheet. Thus, for example, they may be added to the pulp while the latter is in the headl~ox, beater, hydro~ulper or stock chest.
The pi(rment retention and strength a~ents of our invention may, of course, be eCfectively used for addition to pul~ ~re~ared from any types of cellulosic Eibers, synthetic fibers, or cornbinatlons. ~nong the cellulosic materials which may be used are bleached and unbleached sulfate (kraft), bleached and unbleached sulfite, bleached and unbleached soda, neutral sulfite, semi-chemical, chemiground wood, ~round wood or any combination of these fibers. Fibers of the viscose rayon or re~,enerated cellulose type may also be used iE desired.
~ ny desired inert mineral Eillers may be added to the pulp which is to be modified with our novel starch de-rivatives. Such materials include clay, titani~m dioxide, talc, calcium carbonate, calcium sulfate and diatomaceous earths. RoSill or synthetic internal sizer may also be present, iE desired.

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~1057009 With respect to the pr~portion of the starch deriva-tive to be incorporated with the p~per pulp, we have found that this may vary in accordance with the particular pulp involved. In general, we prefer to use about 0.05~/O to 2.0%
of the starch derivative, based on the dry weight of the pulp.
I~ithin this preferred range the precise amount which is used will depend upon the type of pulp being used, the speciEic operating conditions, and the particular end use for which the paper is intended. The use o~ amounts of starch deriva-tive greater than 2%, on the dry weight of the pulp, is notprecluded, but is ordinaril~ unnecessary in order to achieve the desired improvements, ~hen added in the proper concen-trations, our starch derivatives serve to increase pigment retention and paper strength, while providing the finished sheet with improved resistance to folding, pickin~ and scuff-ing.
The starch derivatives employed in our process con-tain cationic aminoalkyl ether or quaternary ammonium groups and sulfo-succinate ester groups in carefully balanced ratios, yielding a combination of charP,es which come into play alternatively under varying conditions of application, such as varying alum concentrations or water hardness. Fur-ther, and surprisingly, the products of our invention by the interaction of the sulfo-succinate cationogenic and cationic groups give a well-balanced performance over a wide range of water hardness and alum concentration. They yiel~ per-Eormance maxima in terms of pip~ment retention and paper strength, at high alum concentrations, not heretofore ob-tainable with starch products containing either cationogenic or cationic or anionic groups alone or combinations thereof as taught by the prior art, This surprising synergistic 1057~09 effect makes our additives significantly suyerior to prior art products within the wide range of operating conditions exist-in~ in the papermaking art utilizing tne presence of more than ~ per cent by weight alum in the dry pulp.
The followin~, exa~ples will further illustrate the embodiments of this invention. Unless otherwise stated, all parts are by weight.

EX~IPLE I
This example illustrates the preparation of a typical alkylamine, phospllate and sulEo-succinate starch de-rivative suitable ~or the practice o-~ this invention.
The method outlined in Example I oE assignee's U.S. Patent llo. 3,459,632 was utilized to modify a quantity of granular corn starch with tertiary amine and phosphate ,roups. The resulting starch derivatives had about 0.3 per cent, by wei~7ht, of nitro~en and, on the same basis, about 0.08 per cent of phosphorus. It is to be noted, since the starch base was phos?horylated, i.e., modiEied witll phosphate ~,roups, conversion of the same was not necessary. The D.S.
of the phosphate groups w~s about 0.008.
Part 1: To chemically introduce the sulfo-succinates to a portion oE the modiied starch described above, about one hundred parts oE said modified starch was suspended in about 125 parts o~ tap water. .The sus~ension ~7as stirred, and the pll oE the resultinr, slurry ~7as adjusted to and !naintained at 7.2 by tlle addition of dilute sodium h~Jdroxide solution, while 1 part of maleic anllydride ~as added in slnall incre-ments. Then the rnixture was allowed to react, as agitation was continued, over a period of about one hour to ensure complete esterification. Therea~ter about G parts o~ sodium ln- -:

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~S7009 metabisulfite were slowly added to the reaction vessel. This mixture was then allowed to react, under agitation and at ambient temperature, for about 16 hours. ~fter the reaction was completed, the pil level of the system was adjusted to 5.5 by the addition of hydrochloric acid. The reaction product was then recovered by filtration, washed essentially free of salts with tap water, and dried. The resultin~
product had a ~.S. of about 0.~28 with respect to the tertiary a~ine groups and a D.S. of about 0.01 ~ith respect to the sulfo-succinate groups. A portion of the dried starch product was then used as an addltive in the preparation of paper and subsequently tested for its pigment retention properties as set forth below.
Part II: Each of three portions oE the starch derivative de-scribed above were added to a bleached sulfite pulp which contained a varied amount of paper al~n, i.e., alu~inum sulfate. Said portions of starch derivative were each added to the paper-making pulp at a concentration of 0.25 per cent, based on the weight o~ the dry pulp. The three pulps respectively contained 4.0, 11.0, and 15.0 per cent, by weight, of alum, based on the total system. In each case, the pigment retention value of the test paper stock and those of a blank and a control were determined by first pre-paring paper sheets on the Williams Standard Sheet ~Iold and then testing ~or the per cent oE titanium dioxide (TiO2) retained by the method described in T~PPI Standard T413-ts-66.
The blank merely consisted of the paper-making stock without any additive, and said control comprised a commercially available pulp having therein a tertiary amine phosphate starch derivative. The test results are presented below.

n/~ TiO2 Retention in presence of follow-amounts of Alum*
Mate_ial_Tested Add_ ive 4.0 _ 11.0 15.0 Test Sample Tertiary ~mine phosphate sulo-succinate starch72 73 72 Blank 43 37 42 Control Tertiary Amine phos?hate 72 56 52 *Based on the per cent, by weight, of the dry pulp.
The data summarized above clearly indicate the improved pi~nent retention obtained hy the use of the novel starch products of this invention.

EX~PLE II
This example further illustrates the increased pi~ment retention effectiveness of the starch derivatives of this in-vention, using a relatively ~,reater amount of sulEo-succinate groups.
The steps set forth in Part I of Example I were re-peated, except two parts of maleic anhydride were used to esterify the modified corn starch prior to sulEonation. The resulting starch derivatives had D.S. values of 0.026 and 0.03 for the tertiary amino grouPs and the sulfo-succinate groups, respectively. When a portion of this starch product was tested in the manner described in Part II of Example I, it displayed pi~,ment retention values comparable to those of the test sarnple in said example.

EX~PLE III
This example illustrates the increased pigment re-tention eEEectiveness oE the starch derivatives oE this inven-tion, usin~, a relatively ~,reater amount of succinating agent with a slightly lesser amount oE sulfonatin~ a~,ent.

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l~D57009 The steps set forth in Part I of Example I were re-peated, except a tertiary amino phosnhate potato starch was further modified with t~/o parts of maleic anhydricle ancl four parts of sodium metabisulfite. The resulting product had D.S. values of 0.03 and 0.02 for the tertiary amino group and the sulfo-succinate ~"roup, respectively. Upon bein~
tested ~y the metho~l outlined in Part II of Exarnple I, this derivative showed Pi~g~nent retention values, in the presence of the varied hi~her amounts o alu~, of 79%, 75CI~, and 76 respectively.

EY~ LE I~
This example illustrates the preparation oE a sulfo-succinate derivative oE a cyclic tertiary arnine starch ether for use as a ~ rnent retention additive Eor paper-mal~in stock.
To make the aclditive describecl above, 100 parts of potato starch w~re slowly stirred into 125 parts of water.
The suspension thus ~ormed was then reacted with 1 part of betachloroethyl piperidine llCl, in the presence of O.S parts of calci~un oxide, over a period o~ about lh hours at ambient temperature. The p~l of the resultin~g~ slurr~ was then ad-~usted to 3.0 by the addition of hydrochloric acid. There-after the reaction product was recovered by Eiltration, washed free o salts, and then reacted with 2 parts of maleic anhydride and ~ parts of sodiurnrnetabisulfite in the manner described in Part I oE rxam?le I to form the tertiary amino, sulfo-succinate starch derivatives. The respective pigment retention values of this derivative, determinecl according to the procedure set forth in Part I of ~xam~le I, ~lere 80, 76, and 76. The product had D.S. values of 0.01 and 0.02 for the ~ ~ 5 7 ~ O 9 tertiary amino group and the sulfo-succinate group, respec-tively. These results reflect the ability of a starch deriva-tive, wherein the starch base contains naturally occurring phosphorus, to be used as a paper additive in accordance with this invention. Furthermore, these results illustrate that, when such a starch base is employed, the conversion step prior to sulfo-succination nay be omitted.

EYl~IPLE V
This example illustrates the preparation of a quaternary ammonium, sulfo-succinate starch derivative which is useful in the practice of this invention.
To make the starch derivative described above, 100 parts of corn starch were slowly stirred into 130 parts of tap water containing ~ ~arts of calci~ hydroxide, the corn starch havin~, a water fluidity of about ~. ~he suspen-sion thus Eormed was then reacted with 3 parts of trimethyl-2-hydroxy-3-chloropropyl ammonium chloride, under agitation and at ambient temperature over a period of about 16 hours.
The pH of the resulting slurry was then adjusted to 3.0 by the addition of hydrochloric acid. Thereafter the reaction product was recovered by filtration, washed essentially free of salts, and then suspended in about 140 parts of water.
l~o parts of maleic anhydride and then 5 parts of sodium metabisulfite were reacted with the quaternary amine modified starch of the suspension, in the manner described in Part I
of ~xample 1. This modified starch product had a quaternary aT~monium group D.S. of 0.01 and a sulEo-succinate group D.S.
of 0.03. Then each of three equal portions of the thusly prepared quaternary ammonium, sulfo-succinate starch de-rivative were added to a particular slurry of a ~aper-making pulp which contained a varied amount of alum. The three pulps respectively contained 4.0, 11.0 and 15.0 per cent, by weight, of alum, based on the total weight of the particular mixture.
The portions of the starch derivative were each added at a concentration of 0.25 per cent by weigrlt, based on the weight of the dry pulp. The pi~ment retention value of each of the respective paper stocks obtained from the aforesaid three test pulps and those of a blank and a commercially available control were determined by the method set forth in Part II
of Rxample I. The paper-makin~ stock in the case of the blank and the control were similar to those respectively em-ployed in Part II of Example I. The test results are pre-sented below.
TiO~ Retention in presence of fo lowing amounts of Alurn*
Material Tested 4.~ 11.0 15.0 Test ~ample13 17 73 ~lank 8 5~ 45 Control 41 -- 64 *Based on the per cent, by wei~,ht, of the dry nulp.
The results ~resented above clearly indicate that the quaternary ammonium, sulfo-succinate starch, derivatives prepared in accordance with this invention are particularly useful in the manufacturing of paper wherein the paper-making stock contains pulp which has a relatively high al~n content.

EXA~PL~: Vl r' This example illustrates t'ne increased pigment re-tention eEEectiveness oE the starch derivatives oE this in-vention, usirlg an alkylamino phosphate, sulfo-succinate starch derivative of which the starch base has been converted 1~357009 . .

by varied acid treatments.
To mal~e each of four test saTnple additives, a tertiary amino phosphate corn starch was prepared by the - -method tau~,ht in Example I of assignee's U.S. Patent 3,459,632, converted to ~ ~water fluidity) levels ran,~ing from about 8 to 35 by treatment with a varied amount of hydrochloric acid, and then further modified with sulfo-succinate groups. The acid conversions were carried out at 52.5C. over a period of about 16 hours. After each reaction was completed, the resulting mixture was neutralized by the addition of dilute NaOI~, and the tertiary amino phosphate starch was recovered by filtration and then washed. Thereafter about 150 parts o each product was further modified by treatment with 2 parts of maleicanhydride and ~ parts of sodium metabisulfite. The D,S. value for the tertiary amine ~roup and for the sulEo-succinate group were 0.~3 and 0.02, respectively. The pig-ment retention values for the four test samples and those of the blank and the three varied controls were determined by the method described in Part II of Example I. The varied amounts of hydrochloric acid used to convertthe starch, the varied amounts of alum employed in the pulp, and the respec-tive test results obtained with the various materials tested are presented in the following table.

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~L~57009 /n Ti~2 Retention in presence of follow-~aterial ~ICl ing amounts of Alum*
Tested (Parts) 4.0 11.0 Sample A Tert;ary ~ine phos- 0.25 79 75 phate sulfo-succinate starch Sample ~ (Same as that used in 0.5 81 90 Sample A) Sample C " " " " " " 0.75 73 75 Sample D " " " " " " 1.0 74 75 l~l Tertiary ~nine ~tarch --- 56 46 Control Tertiary Amine, phos- --- 7~ 5 ~,'2 phate starch Control Tertiary Amine, su'fo- ---- 6r) 59 ,1,~3 succinate of a non-converted starch Blank ------__ ___ ________ ___ ~ l~5 *Based on per cent, by weight, of the dry pulp.

The data summarized above clearly indicate that in order to obtain improved pip,ment retention, in accordance with this invention, it is imperative that the base starch be con-verted as well as modified ~ith the nitro~en containing groups and the sulfo-succinate ~,roups.

r.XAMPLF. VII
This example illustrates the useEulness o~ a starch derivative of this invention, as an additive ~or paper-makin~
pulp, wherein the base starch o~ the derivative has been con-verted prior to modification. Also, this example further il-lustrates the crucial nature of the conversion step in the preparation of the paper-making additives of this invention.
A test sample additive was prepared by treating a quantity of corn starch with 0.5~ ICl to a r~ Of about 10, lQ157~9 then diethylamino ethylating the s~arch by the method taught in Part A of Example l of assignee's U.S. Patent 3,459,632, and thereafter further modif~Jing the starch with sulfo-succinate ~roups by the metl.10d outlined in Part I of Example I. The resulting starch product had a diethylamino ethyl group D.S. of 0.03 and a sulfo-succinate group D.S. of about 0.02. This test sam~le additive and four varied controls were added to bleached pulp at concentrations of 0.25V/~ based on the weight of the dry pulp. Pigment retention values were determined for each additive and a blank at varied levels of alum as described in Part II of Exa~ple I. The identifica- -tion of the controls and their respective descriptions were as follows:
Control No. l - Corn starch modified ~7ith sulfo-succinate groups (D.S. o~ about 0.02) by the method set forth in Part I oE ~xarnple I.
Control No. 2 - Corn starch modified ~ith diethylamino ethyl roups (D.S. of about 0.03) by the method set forth in Part A of Example I of assignee's U.S. Patent 3,459,632.
Control No. 3 - Corn starch modified with both diethylamino ethyl groups (D.S. of about 0.03) and sulfo-succinate ~roups (D.S. of about 0.02) by the respective methods mentioned above.
Control No. 4 - Corn starch which has been acid-converted in the same manner as the starch base of the test sample herein and thereafter modified with diethylamino ethyl ;,roups (D.S. of about 0.03) by the method taught in Part I~ of assignee's U.S. Patent 3,459,632.

~1~ 57C~O~

The results of the pigment retention determinations for the above-described test sample additive, the four control additives, and the blank are presented in the following table.

% TiO2 Retention in presence of following amounts of Alum*
Material Tested 4.0ll.0 ___ Test Sample 69 71 Control ~10. l 62 59 Control No. 2 56 46 Control No. 3 ~0 59 n Control No. 4 52 46 Blank (pulp without an additive) *Based on per cent, by weight, oE
the dry pulp.

The data obtained for the test sample and control No. 3 in the above table clearly indicate the outstanding pig-ment retention performance of the starch derivatives of this invention wherein the starch base is converted prior to being esteriEied.
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EX~Lr~ VIII
This example further illustrates the improved pigment retention properties of an aminoalkylate, sulfo-succinate starch derivative oE which the starch base has been acid-converted prior to esterification with a varied amount o-E maleic anhydride.
To make each of three test sample additives, a quantity of tertiary amine corn starch was prepared by the method taught in Example I of assi~,nee's U.S. Patent 3,459,632 and then converted to a ~ of about 8 by treatment with 0.5 ~arts of HCl. The resulting, converted starch product was :

.

1057~(19 then divided into three equal portions. Each of the portions ~ -of the starch product was esterified with a varied amount of maleic anhydride and thereafter sulConated by reaction ~ith four parts of sodi~n metabisulfite. The acid conversions were carried out at 52.5C. over a period of 16 hours. ~ach of the tertiary amino, sulfo-succinate starch derivaties thus obtained was recovered by Eiltration, washed, and dried. These test sample additives, two commercially available paper-making starch additives, and a blank ~ere tested for their ~igment re-tention properties by the method described in Part II of Example I. The amount of maleic anhydride used in the preparation of each of the test saMple additives and the corresponding terti-ary amino group to sulfo-succinate vroup ration therein, the de-scriptions oE the t~o controls, and all test results are pre-sented in the following table.
D.S. of D.S. of TiO2 Retention sulfo- tertiary- in presence of Material succinate amino Alum Tested AdditiveP,roups ~roup 4.0 11.0 Sample E Tertiary amineO.nl 0.03 75 74 sulfo-succinate starch Sample F (Same as that used in Sample E) 0.02 0.03 76 74 Sample G (Same as that used in Sample E) 0.03 0.03 77 77 Control Tertiary amino- 55 48 #l alkyl ether of starch (prepared by the procedure de-scribed in Ex. 1 of U.S. 2,813,093) Control Phosphorylated 75 56 #2 tertiary amino-alkyl ether of starch (prepared by the procedure de-scribed in Ex. 1 of U.S. 3,459,632 (D.S.
of about 0.03) Blank 41 43 , - . : - : - , ~57 O O 9 The data surm~arized hereinabove clearly indicate the improved pigment retention obtained by the use of the novel products of this invention. It furt'ner indicates that the extremely high percentages oE pig~ent were consistently re-tained in the presence of greater amounts of alurn, only where the test sample additives were used.

EX~P_E IX
This example illustrates the usefulness of thin boil-in~, starches in the preparation of the novel starch paper addi-tive.s of this invention.
To tnake each of the two test sa~ple additives, the procedural steps set forth in Example VII were repeated, except a thin boilin~ waxy maize which had a particular Water Fluidity (WT) was used in each case. Each of the resulting starch de-rivatives had a tertiary a~ine ~,roup D.S. of about 0.~3 and a sulfo-succinate group ~.~. of about O.n3. The two test sam-ple additives and a blank were then tested in the manner de-scribed in Part II of Example I. The WF's of the waxy maize used to prepared the additives and the pigment retention de-terminations are presented below.

% TiO2 Retained in the presence of the following amounts of Alum Material Tested ~F 4.0 parts 11.0 parts Test Sample TT 24 72 79 Test Sample 1 36 68 76 Blank -- 43 ~5 The data sur~narized above clearly indicate the im-proved pigment retention obtained by the use of the novel products of this invention prepared with thin boiling starch bases. It Eurther indicates the ability of the products of '~0570V9 this invention to consistently retain greater amounts of pig- ~-ment despite a substan~ial increase in the amount of alum used. ~

~JXAMPL~ X
This example illustrates the usefulness of a starch derivative as a paper additive, wherein the starch base has been simultaneously converted by homolytic oxidation and etheriEied with aminoalkyl ~roups prior to esterification.
In order to make a starch derivative in the above described manner, 100 ~arts o~ corn starch were suspended in about 125 parts of tap water at about 40C. The pll of the re-sulting slurry was adjusted to 11.2 by the addition of dilute sodium hydroxide. Then 3 parts of diethylamino-ethylchloride ~ ~ICl, 0.5 parts of calcium hydroxide, and O.S parts of 30/~
aqueous hydrogen peroxide were added to the slurry. While the p}l was maintained at the aforesaid level, the mixture was agitated for about 17 hours. Therea~ter, the pH of the re-action mixture ~Jas adjusted to 3.0 by the addition of dilute hydrochloric acid, and the reaction product was recovered by filtration and thorou~hly washed. It was determined that the converted starch had a WF of about 7. This intermediate base was then suspended in water at a ratio of 1.0 part per 1.3 parts of water, reacted with 2.0 ~arts of maleic anhydride and thereafter with 4.0 parts of sodium metabisulfite. The thusly prepared diethylaminoethyl, sulfo-succinate starch de-rivative was recovered in the manner described in Part I of Example I. This starch derivative had diethylaminoethyl group and sulfo-succinate group ~.S. values of 0.03 and 0.02, respectively. Then this derivative, a commercially available control and a blank were tested for their pigment retention properties by the method outlined in Part II of Example I. The ~' .

lC~57~09 control consisted of a standard paper-making stock containing an aminoalkyl etheri-Eied and phosphorylated starch additive, and the blank merely consisted or the paper-rnaking stock. The test results were as follows:

/O TiO Retention in presence of fo~lo~ling parts of Alum ~aterial Tested 4.0 11.0 Test Sample 74 70 Control 71 61 Blank 43 45 The data summarized above clearly indicate the im-proved pi~ment retention consistently obtained by the use of the novel products of this invention in the presence of high as well as low amounts of alum.
"' EXAMPLE XI
This example further illustrates the usefulness of a starch derivative as a paper additive, wherein the starch base has been simultaneously converted by oxidation and etherified with aminoalkyl groups prior to esterification.
The procedural steps of Example X were repeated, except only 0.1 parts of 30/O aqueous hydrogen peroxide was used without any calcium hydroxide, and the etherification was carried out over a period o~ only 5.75 hours. T1hen tested by the method described in Part II of Example I here-inabove, this diethylaminoethyl (D.S. of about 0.03) sulfo-succinate (D.S. of about 0.02) starcll derivative showed pig-ment retention values comparable to those of the test sample in ~xample X.

. . .~ . : . . .

~057Q~9 EXA~LE XII
This example illustrates the improved burst stren~th which is obtained with the use of our novel additives as com- -pared with the strength of eit'ner untreated sheets or sheets treated with a conventional diethylamino ethyl ether o a phosphorylated starch.
~ ~uantity of a diet'nylamino etllyl ether and sulfo-succinate derivative, havin~ a ~ormulation similar to that of the test sample in ~xample VI, was prepared according to the general procedure set forth in Part I of Example I.
With a~itation, t~o test safilple paper-makin~
stoclcs, ~T and I, were prepared by adding a varied amount of the above-described starch additives to an unbleached pulp containing 11.0 parts of alum, based on the weight of the dry pulp. The starch additive additions were made, to dilute the paper stock, at concentrations of n. 5 and 1.5 per cent, respectively, based on the dry weight oE the ~ulp. ~heets were then prepared from each of the pulp stocks on a r~illial~s Standard Sheet ~Iold.
The stren~,th of these she~ts was deter~ined using the Mullen tester according to procedures set forth in TAPPI
Standards T403, ts-63. In this a~paratus a sheet of paper is clatnped between two ring shaped platens, thus leaving an exposed circular surface of paper under which there is an inElatable rubber diaphra~,m. As air is ~umped into this diaphragm it expands and comes into contact with the exposed surface of the paper. I~ote is made o the pressure, ln p.s.i., at which the diaphra~m caused the paper to burst.
The Mullen Eactor is then calculated by dividing the latter Eigure by the basis weight of the paper, a higher .Iullen factor thus indicating a stronger paper.

1(~57~09 Using the same paper-mal~in~ procedure as described above, comparabl~ sheets were prepared with, in one case, a control comprised of the standard pulp stock having a conven-tional diethylamino ethyl ether of starch additive therein and, in another case, the standard pulp stock without an ad-ditive. The test results in terms of ~lullen values were as follo~s: ; ;

?~aterial Tested C/ Additive ?lullen Mullen Factor O ~
I'est Sample ~1 0.5 77.6 1.44 10 Test Sample I 1.5 92.3 1.59 Control n. 5 66.8 1.32 Control 1.5 76.8 1.45 ~lank --- 60.7 1.12 -The data presented above clearly show the improved bursting stren~,th oE the sheets obtained with pulp containing our additive.
Although it will be noted that in some cases the novel starch derivative containing both the cationic or cationogenic aminoalkyl ether groups and the sulfo-succinate ~0 ~,roups is not siKnificantly more effective at the low con-centrations of alum than a starch derivative which contains aminoalkyl ether groups in combination with only phosphate ~roups, the important factor is that the novel derivative is effective as a pigment retention and strength additive in the presence of higher as well as low concentrations of alum.
These improvements in the quality of the paper, par~icularly with regard to pigment retention, are greater than anything that could heretofore be achieved by the addition to paper pulps of corresponding amounts of other starch derivatives, 3n or any combinations of such derivatives.
Summarizing, our invention is thus seen to provide .

~ 57~09 the practitioner with novel paper additives which are functional under a wide variety of conditions and are capable of providing paper products which are characterized by their excellent pig- :
ment retention as well as increased strength.
Variations may be made in proportions, procedures, and rnaterials without departing from the scope of this inven-tion which is de~ined by, but not limited to, the Eollowing clairns.

Claims (7)

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

1. A paper containing pigment and alum and having dispersed therein as a pigment retention aid a starch derivative of an ungelatinized starch base having a water fluidity between 4 and 40, said starch derivative containing chemically introduced sulfo-succinate groups and cationogenic or cationic nitrogen containing ether-linked substituent groups selected from the group consisting of primary amine, secondary amine, tertiary amine and quaternary ammonium groups wherein the degree of substitution of said cationogenic or cationic nitrogen containing substituent groups in said starch derivative is about 0.005 to 1.50, and the degree of substitution of said sulfo-succinate groups is at least 0.008, said paper being prepared from a papermaking stock containing from about 0.05 to 2.0% of said starch derivative by weight of dry pulp.

2. The paper of Claim 1, wherein the paper making stock contains more than 4% alum by weight of dry pulp.

3. The paper of Claim 1, wherein the starch base is corn starch or phosphate substituted corn starch.

4. The paper of Claim 3, wherein said cationic or cationogenic nitrogen containing groups in said starch derivative are diethyl aminoethyl groups and the degree of substitution is about 0.02 to 0.04.

5. In a method for making paper containing pigment and alum, the step which comprises adding as a pigment retention aid to the stock contain-ing more than 4% alum by weight of dry pulp, at any stage prior to forming a web, a starch derivative of an ungelatinized starch base having a water fluidity between 4 and 40, said starch derivative containing chemically introduced sulfo-succinate groups and cationogenic or cationic nitrogen containing ether-linked substituent groups selected from the group consist-ing of primary amine, secondary amine, tertiary amine and quaternary ammonium groups wherein the degree of substitution of said cationogenic or cationic nitrogen containing substituent groups in said starch derivative is about 0.005 to about 1.50, and the degree of substitution of said sulfo-succinate groups is at least 0.008, said paper being prepared from a paper making stock containing from about 0.05 to 2.0% of said starch derivative by weight of dry pulp.

6. The method of Claim 5, wherein the starch base is corn starch or phosphate substituted corn starch.

7. The method of Claim 6, wherein said cationic or cationogenic nitrogen groups in said starch derivative are diethyl aminoethyl groups and the degree of substitution is about 0.02 to 0.04.