FI57117C - DERIVATIVES OF I DIFFERENTIAL DISPENSERS OF POLYACKERS WITHOUT PAPERSTILLVERKNING AND CHARACTERISTICS OF DESS FRAMSTAELLNING - Google Patents

Description

Ιμ £ * »· Ι Γβ1 advertisement publication c 71 1 7 ^ j§HA LBJ (11) UTLÄCGNINGSSKRIFT 3/1 1 'C Patent nyjnnotty 13 06 1333

Patent ccdJelat ^ v ^ (51) Kv.lk. '/ Int.CI. * C 08 B 31/08 C 08 B 11/00 FINLAND - FINLAND (21) p «* nttlh * k» "' u» -PttenttMÖknIng 53 ** / 73 (22) Hakcmltpilvl - Aiuttknlngadig 22.02.73 * '(23) AlkupUvI - Glltlghtttdag 22.02.73 (41) Tullut JulkiMksI - Bllvlt offuntllg 01.10.73

Patent and registration filing · .... .........,. . .....

_. * (44) Date of issue and date of issue. -

Patent * oeh regiateratyrelsen '· Antöktn utl »gd och utl. * KrHt« n published 29.02.80 (32) (33) (31) Requested »tuolkeui —Begird priorltet 31.03.72 USA (US) 21 * 0279 (71) National Starch and Chemical Corporation, Delaware, US; 750 Third Avenue, New York, New York 10017, USA (72) Wadym Jarowenko, Plainfield, New Jersey, USA (7 * 0 Oy Borenius & Co Ab (5 * 0 Water-dispersible polysaccharide for papermaking derivative and method for its preparation - Derivat av i vatten dispers-gerbar polysackarid avsedd för papperstillverkning och förfarande för dess framställning

The invention relates to the preparation of new derivatives of water-dispersible polysaccharides in the form of colloidal dispersions for use as flocculants or pigment retention agents or strength agents in the manufacture of paper. In particular, it relates to the preparation of cationic polysaccharides using polyfunctional derivatizing reagents.

As used herein, the term "paper" refers to sheet-like pulps and products formed from fibrous materials, which may be derived from "natural sources, such as cellulose, or may be synthetic, such as polyamides, polyesters and polyacrylic resins, as well as derived from mineral fibers, such as asbestos and It also includes papers made from a combination of cellulosic and synthetic materials, as well as papers made from mixtures of cellulose and asbestos and fiberglass.The paperboard naturally belongs to the broad term "paper".

It is known to add various substances, such as starch, to the cellulosic pulp during papermaking before forming the sheet. The main function of such additives has been to bind the private fibers together, thus providing a stronger paper. In addition, in the case of papers containing added pigments, such as D 21 H 3/28, C 02 B 1/20 2 57117 e.g. titanium dioxide, calcium carbonate and the like, it has been known to add substances to the pulp for a specific purpose in order to retain such pigments in a larger amount in the paper. (rather than leaving them in the water removed during sheet formation). Such additives are often referred to as pigment retention agents.

Cationic flocculants and paper additives are well known in the past and have been described in numerous patents and writings. (E.F. Paschall, "Production and Use of Cationic Starches," R.L. Whistler and E.F. Paschall, Eds., Starch: Chemistry and Technology, Vol. II, Academic Press, New York, 1967, pp. 403-433). Known methods for preparing such substances have used derivatizing reagents in which one group per molecule is reactive with the hydroxyl groups of the starch or resin. According to these methods, the polysaccharide is dispersed in an aqueous medium at a relatively high concentration (usually more than 35%) and reacted with a monofunctional derivatizing agent. Under these conditions, cross-linked, insoluble substances are formed upon reaction with polyfunctional derivatizing reagents. Because the flocculant must be completely dispersed in water to be effective, polyfunctional derivatizing agents have not previously been used to incorporate cationic groups into polysaccharides such as starch and natural resins to produce effective flocculants and / or pigment retention agents for papermaking.

In addition, according to known methods, cationic flocculants and papermaking additives are purified and recovered from the reaction mixture by washing and drying. After drying, they are packaged and transported to the place of use, where they are redispersed in water and boiled before being added to the pulp. Several steps make this treatment complicated and relatively expensive.

It is an object of the present invention to provide novel flocculant and pigment retention agents and polysaccharide derivatives useful as strength enhancers. According to the invention, these derivatives are prepared by reacting a water-dispersible polysaccharide colloidally dispersed in an aqueous alkaline solution, under alkaline conditions at a temperature of 25 to 160 ° C and at a concentration low enough to prevent the formation of agglomerates, wherein a non-polymeric derivative is formed. at least one cationic group and at least two functional groups capable of reacting with a water-dispersible polysaccharide, said reagent being an amine containing at least two non-halohydrin functional, polysaccharide-reactive groups such as chlorine atoms or activated double bonds, cyclic amine, cyclic contains at least two functional groups reactive with polysaccharides, condensation product of amine and polyamine with aldehyde and polyaldehyde or formaldehyde-acetone-amine condensate.

The invention also relates to a process for the preparation of these novel polysaccharide derivatives.

The water-dispersible polysaccharides which can be used in the process of the invention may be of vegetable or animal origin and include starch and starch fractions such as amylose and amylopectin, starch derivatives, soluble rennet, cellulosic resins and soluble, soluble or soluble cellulose derivatives such as methylated cellulose, hydroxyethylcellulose or hydroxypropylcellulose. In order to be suitable for the purpose of the invention, these polysaccharides must be able to form complete dispersions in water and must have a sufficient number of hydroxyl, amido or amino groups containing active hydrogen atoms in the molecule which react with an effective amount of the derivatizing reagent. These active hydrogen-containing groups may be attached to the anhydroglucose backbone of the polysaccharide as in the case of natural starches, cellulose and natural resins, or may be attached to side chains, optionally by chemical reaction to a polysaccharide molecule such as hydroxyalkylated alkido . Thus, for purposes of the invention, a polysaccharide means any polysaccharide having hydroxyl or other active hydrogen-containing groups, either naturally or provided by derivatives. Because the flocculating efficiency of a flocculant is usually proportional to its molecular size, high molecular weight polysaccharides are preferred starting materials if they are dispersed in an aqueous medium. A few, such as amylopectin, are dispersible in cold water; others, such as amylose, form gels in cold water and must be boiled under pressure or dispersed in an alkaline medium. Cellulose can be utilized to form xanthate or other water-dispersible derivatives.

Starches which can be used as a base for the reaction with a polyfunctional derivatizing agent can be used in their original naturally occurring form or in a modified form, such as those obtained by controlled decomposition (thermal, acid or oxidative decomposition), etherification and / or esterification, provided that they can be further converted to the cationic derivatives described above. Thus, starches to which phosphate ester groups have been attached can be readily used provided that they still have reactive hydroxyl groups. Likewise, starch derivatives such as aminoalkylated starches may be used provided that they have hydroxyl groups or other active hydrogen-containing groups in either the anhydroglucose backbone or the derived groups. These starch bases can be obtained from various sources such as corn, amylose-rich corn, wheat, potato, tapioca, waxy corn, sago and rice as well as the amylose and amylopectin fractions of starch. The term "starch" thus includes amylase-containing substances, whether modified or unmodified and still containing free hydroxyl groups. the intended end use of the product.

In the aqueous dispersions of polysaccharides used in the new process according to the invention, the polysaccharides must be dispersed as completely as possible so that the dispersions flow easily and are free of any gel-like particles. Satisfactory dispersions are those known as fine colloidal dispersions. Ideally, the polysaccharides are molecularly dispersed, but in all cases they must be so dispersed that the molecular aggregates are as small as possible. It will be apparent to those skilled in the art that when polysaccharides react with a reagent that can cross-link molecules, the larger molecular aggregates s 57117 cross-link internally in such a way that they cannot be dispersed and are therefore unusable as flocculants. Even a large number of larger colloidal particles in the polysaccharide dispersion cause deterioration of the flocculant. Thus, preferred polysaccharide dispersions are those as close as possible to the ideal form of molecular dispersion. In particular, natural starches in granular form must be gelatinized and converted to a fine colloidal dispersion either before the starch reacts with the derivatizing agent or simultaneously with a reaction that may occur when the reaction is carried out in a continuous digester, as described later. To obtain the desired high degree of dispersion of the carrier, well-known physical and chemical techniques can be used, such as high shear mixing, boiling if desired under pressure, and dispersion in a strongly alkaline medium, as is known to those skilled in the art. The concentration of the polysaccharide in the dispersion is also an important factor in obtaining the correct degree of dispersion. High molecular weight substances may require concentrations of less than 1.0% by weight to obtain a satisfactory dispersion, while low molecular weight substances, e.g. waxy maize, have been acid decomposed to a viscosity of 85 on a scale of 100 (Water Viscosity). fluidity 85), can give satisfactory dispersions at concentrations as high as 30% solids. In general, useful concentrations for a polysaccharide dispersion are less than 4.5% solids.

Cationic substituent groups that can be attached by the novel process of the invention include primary amine groups, secondary amine groups, tertiary amine groups, quaternary ammonium groups, pseudourea groups, cyclic amino and imino groups, such as pyrrole, pyridine, pyrrolidine, pyrrolidine, pyrrolidine, such as polyamine, amine amide and guanidine groups. It is to be understood that the term "cationic substituent group" means substituent groups of any of the above groups or a derivative thereof. The term "cationic polysaccharide dispersions" thus encompasses polysaccharide dispersions which contain any of the above groups despite the electrostatic charge of the polysaccharide derivative, which depends on the equilibrium of the cationic and anionic groups and the pH of the medium.

6 57117

The polyfunctional derivatizing reagents used in this invention have at least one cationic group and two or more groups that react with the hydroxyl groups of the starch molecule. Such reactive groups are known in the art and are e.g. halide groups, preferably chlorine groups, epoxides, polyaldehydes and activated double bonds. Suitable polyfunctional reagents include N-beta-chloroethyl 4- (3-chloropropyl) -piperidine hydrochloride, tris-beta-chloroethylamine hydrochloride and formaldehyde-acetone-amine condensates.

These polyfunctional derivatizing reagents can also be crude reaction products of guanidine and various polyamines such as ethylenediamine, 1,3-propanediamine, 1,5-pentanediamine, N, N-dialkylpropanediamine and diethylenetriamine with polyfunctional reagents such as with epichlorohydrin, 1H-dichlorobutane, acrolein and the like. They may also be crude reaction products of various cyclic amines such as morpholine, imidazole, aminopyridine and aromatic amines such as aniline and phenylenediamine with a polyfunctional compound such as epichlorohydrin. Any amine compound having at least one amino nitrogen containing at least one reactive hydrogen atom attached to that nitrogen can be used to prepare a polyfunctional aminoalkylating agent by reacting it with more than one mole of epichlorohydrin or other polyfunctional reagent. Useful polyamines include alkylenediamines in which the alkylene group contains 2 to 6 carbon atoms, and substituted alkylenediamines such as Ν, Ν-dialkylalkylenediamines and tetraalkylalkylenediamines in which the total number of alkyl groups of the alkyl groups is preferably at most 22.

The amount of polyfunctional reagent used in the process of the invention is usually at least the amount required to form a satisfactory flocculant. In general, satisfactory results are obtained using about 3 to U% by weight of a polyfunctional reagent based on the polysaccharide. However, larger or smaller amounts may be used if desired.

Since the above reaction is catalyzed by a base, the reaction is carried out under alkaline conditions. In addition, since the reaction 7 57117 usually forms an acid as a by-product, an excess of base must be added to neutralize the acid and maintain the required basic condition. Any soluble alkali or alkaline salt such as sodium hydroxide, potassium hydroxide, trisodium phosphate, borax, tertiary amines, quaternary amines and guanidines can be used. The amount of base required in the reaction mixture to solubilize the polysaccharide, catalyze the reaction, and neutralize the liberated acid will vary depending on the reagents and conditions used. In this case, at least "a sufficient amount of base must be used to neutralize the acid liberated.

This amount varies depending on the amount of polyfunctional agent used, but the equivalent amount can be easily calculated after the amount of polyfunctional agent has been determined. Larger amounts may be used and may be particularly advantageous in certain cases to improve the dispersion of the polysaccharide.

The polyfunctional reagents used to form polysaccharide derivatives in accordance with the invention can also crosslink polysaccharide molecules. Excess cross-linking can result in insoluble substances that are not useful as flocculants; therefore, the amount of crosslinking that occurs during the reaction must be limited.

Crosslinking can be limited by using dilute dispersions of the polysaccharide to be treated. High molecular weight polysaccharides, such as natural starch, must be used as very dilute dispersions because only a small amount of crosslinking needs to occur to form an insoluble product. In general, a concentration of less than 4.5% must be used when treating non-degradable polysaccharides such as natural starches. In the case of low molecular weight substances, a higher amount of cross-linking may occur before insoluble substances are formed. Thus, such substances, e.g. decomposed starch, can be reacted at a concentration of up to 30%.

The reaction temperature and duration can also be adjusted to limit the amount of undesired crosslinking. In general, low temperatures and short reaction times tend to reduce crosslinking. One skilled in the art will readily recognize that certain derivatizing reagents 8 571 1 7 are more reactive with polysaccharides than other reagents and are therefore more sensitive to cross-linking products, so care must be taken to avoid unwanted cross-linking when using such reagents.

If desired, the reaction of the polysaccharide with the polyfunctional derivatizing agent can be performed in the presence of a crosslinking inhibitor that reduces crosslinking during the reaction. Such inhibitors are compounds that react with one reactive group of a polyfunctional derivatizing reagent that is thus not available for reaction with a polysaccharide. Useful cross-linking inhibitors are water-soluble compounds containing amino and / or hydroxyl groups, salts of organic acids or organic halo acids. Suitable compounds include amines such as ammonium hydroxide, ethylamine and diethylamine; amino alcohols such as ethanolamine and triethanolamine amides such as formamide and haloacid salts such as sodium chloroacetate. These compounds may be present in a concentration of about 1 to 15% by weight based on the weight of the polysaccharide.

Polyfunctional derivatizing reagents may contain reactive groups having equal or different reactivity to the polysaccharide. Various reactive groups include, for example, N-beta-haloethyl groups, especially N-beta-bromoethyl and N-beta-chloroethyl groups. An example of a reagent with three different reactive groups is tris-beta-chloroethylamine hydrochloride. Moderately reactive groups include the N-3-chloro-2-hydroxypropyl group, while low reactive groups include the reactive groups present in N-halopropyl and formaldehyde / acetone / amine condensates. Preferred reagents contain at most one highly reactive group and at most one less reactive group. A preferred reagent of this type is N-beta-chloroethyl-H- (3-chloropropyl) -piperidine hydrochloride.

Reagents containing more than one highly reactive group are, of course, highly effective crosslinking agents, and care must be taken when using such reagents to avoid undesired crosslinking of the polysaccharide and consequently poor flocculants. Such cross-linking can be minimized by adding reagents to dilute, fine colloidal dispersions of polysaccharides, using low molecular weight polysaccharides that give dispersions of relatively low viscosity, and performing the reaction in the presence of cross-linking inhibitors.

If it is desired to prepare a derivative of a polysaccharide, such as starch, with a polyfunctional reagent which is not too reactive with respect to the polysaccharide, i. a reagent containing at most one group which reacts with the polysaccharide as rapidly as the beta-chloroethyl group may be conveniently carried out in a continuous digester. The term "continuous digester" means a device comprising a closed system, well known in the treatment of starch, comprising a device through which starch slurry is continuously passed. When used to prepare starch derivatives in accordance with the invention, the continuous digester comprises means for rapidly heating the reaction slurry to temperatures of about 80-160 ° C or higher, usually by spraying fresh steam so that the starch is removed in a gelatinized ("cooked") state. In a continuous cooking process, the conversion of starch to gelatin occurs substantially simultaneously with its reaction with a derivatizing reagent to incorporate cationic substituent groups.

By using a continuous cooking method, the starch product can be prepared at its potential place of use and thus a continuous flow of the product can be obtained immediately.

Thus, the reaction of starch with a polyfunctional derivatizing reagent having a cationic group can be performed by mixing the reagent with a slurry of natural starch in water at a pH above 10.5 and passing the slurry through a continuous digester at temperatures of 80 to 160 ° C or higher. The starch is gelatinized and derivatized simultaneously by this treatment, and the reaction mixture can be added just as it exits the digester to the wet end of the papermaking machine. In some cases, it may be more convenient to spray the reagent and / or catalyst directly into a continuous digester chamber or stream exiting the digester chamber.

When polysaccharide substances which do not need to be gelatinized, such as already gelatinized starch or dispersed cellulose derivatives, are used in the process according to the invention or when the derivatizing reagents are so reactive that they cross-link the starch when can be conveniently carried out in aqueous dispersion at a temperature of 25 to 100 ° C and an alkaline pH range. The reaction can be terminated just before harmful crosslinking occurs by acidifying the reaction mixture to pH 7 or below.

The polysaccharide derivatives according to the invention can be used as a paper pigment retention agent and a strength-increasing agent or as a flocculant in a manner known per se. However, the use of the reaction mixtures prepared by the process of the invention by adding them directly to the wet end of a papermaking machine eliminates the number of steps normally required to prepare cationic flocculants and strength agents for use in papermaking, and thus provides economic benefits. The paper produced using the derivatives prepared by the process of the invention is comparable in quality to paper obtained using conventional pigment retention agents and strength agents.

The polysaccharide derivatives prepared by the process of the invention are useful not only in the manufacture of paper, but also as flocculants in water and water treatment.

The invention is described with reference to the following examples. All parts are by weight unless otherwise indicated.

11 57117

Example I

This example illustrates the preparation and use of the modified starch of the invention.

To 60 parts of waxy corn starch slurried in 1940 parts of water are added 4.8 parts of sodium hydroxide and 2.4 parts of N-2-chloroethyl 4- (3-chloropropyl) piperidine hydrochloride. The resulting mixture is immediately passed through a continuous digester at 150 ° C at a rate of 100 ml of slurry per minute. The resulting colloidal solution has a pH of 11.5 and contains 2.6% solids.

While the colloidal solution is still warm, it is added to the bleached sulphite pulp (degree of grinding 400) in an amount to give 0.25% by weight of solids derived from the treated starch dispersion, based on the solids in the pulp. The pulp also contains 10% by weight of titanium dioxide pigment. The pulp is formed into sheets of paper by hand. The resulting handmade sheets are incinerated and the pigment residue is weighed to determine the percentage of pigment retained on the paper. The percentages of pigment retention in the product of this example compared to the corresponding values of a control sample made using a pigment retention aid made according to U.S. Patent No. 2,813,093 and the corresponding values of an untreated sample that did not contain a pigment retention aid are summarized in Table. .

Table I

Pigment retention (%) at pH 7.6 9.5

Product of Example I 67 61

Well-known products 64 55

Blind test 12 17 12 5711 7

Example II

This example illustrates the preparation of a cationic paper strength and pigment retention enhancer in accordance with the invention using a highly reactive, polyfunctional aminoalkylating agent.

A total of 60 parts of corn starch is suspended in 2940 parts of cold water containing 4.8 parts of sodium hydroxide, and the slurry is passed through a continuous digester at 150 ° C. To this obtained colloidal starch solution, 2.4 parts of tris-Heta-chloroethylamine hydrochloride are added with stirring and samples are taken after 5, 10, 20 and 30 minutes. The samples are immediately acidified to pH 3 with hydrochloric acid to stop the reaction and then stored in closed containers. The reaction temperature was 95-5 ° C.

The products obtained from each sample are added in an amount of 0.25% solids obtained from the treated starch dispersion, calculated on the pulp solids, to a bleached sulphite pulp containing 10% titanium dioxide. The pulp is manually formed into sheets and the sheets are examined according to Example I to determine pigment retention. Similarly, the products of each sample are added in an amount of 0.5 to 1.5% solids based on the solids in the pulp to the bleached sulfate cellulose pulp. These pulp samples are made into sheets by hand and the puncture strength of the sheets is determined by the Mullen method. Pigment retention values and puncture strengths are given in Table II.

Table II

Reaction- Pigment retention- Mullen coefficient at the following timing (%)% values Sample no. (minutes) at pH 7.6 0.5_1.0_1.5 1 5 60 1.63 1.63 1.66 2 10 61 1.59 1.66 1.74 3 20 57 1.58 1.65 1.74 4 30 49 1.40 1.54 1.48

Control; Known Product 59 1.44 1.70 1.66

Blind test 23 1.32

The results obtained show that these products have a good ability to act as a pigment retention and strength agent, but the 13 5711 7 reaction must not be continued to such an extent that harmful cross-linking occurs, i. for up to about 50 minutes at a temperature of about 70 ° C.

Example III

This example illustrates the preparation of a cationic starch-pigment retention agent by means of a continuous digester using formaldehyde-acetone-amine condensates. Preparation of reagents: A. A total of 20 g of water and 0.25 g of sodium hydroxide are placed in a comma-necked round bottom flask equipped with a stirrer, reflux condenser and addition funnel. To this mixture are added 5.8 g of acetone and 17 g of a 50% aqueous solution of formaldehyde. The mixture is then heated to reflux and maintained at this temperature for about 15 minutes. 20 g of N-methylpiperazine in 50 g of water are then added and heating is continued for a further 15 minutes. The mixture is diluted to a total volume of 200 ml and stored in containers. The mixture contains about 11% solids.

£. After the treatment described in A, the following ingredients are reacted with each other:

Formaldehyde (57% aqueous solution) 56.6 g

Acetone 5 * 8 g

Sodium hydroxide 0.5 g N, N-dimethylpropanediamine 20.4 g

Water 50 g C. After the treatment described in A, the following ingredients are reacted:

Formaldehyde (57% aqueous solution) 56.6 g

Acetone 5 · 8 g

Sodium hydroxide 0.5 g

Ethylenediamine 12.0 g

Water 50 g

The resulting mixture is diluted with water to a volume of 200 ml. It contains 7.5% solids.

Reaction in a continuous digester:

A total of 60 parts of corn starch is suspended in 1940 parts of water with 2.4 parts of sodium hydroxide. To this slurry is added 54.5 parts of the solution of product A prepared above, and the mixture is passed through a continuous digester at a temperature of 140-150 ° C at a rate of 57,117 m per 100 ml per minute. Likewise, 30.0 parts of the product B solution and 80.0 parts of the product C solution are suspended in similar amounts of corn starch suspended in water, and the resulting mixtures are passed through a continuous digester as described above.

Samples of the dispersions prepared by the reactions in a continuous digester are added at a concentration of 0.25% solids, calculated from the solids of the pulp, to a bleached sulfite pulp (400 ml degree of grinding) containing 10% titanium dioxide. The pulp sample is then manually made into sheets, the sample sheets are incinerated and the retention of the holder is determined as described in Example I. Table III shows the pigment retention values of products A, B and C compared to the known product.

Table III

Retention agent Retention (%) at pH 6.0

Maize starch reacted with A 59

Maize starch reacted with B 53

Maize starch reacted with C 61

Well-known starch product 48 ... 50

Blind test 46

Example IV

This example shows the reaction of cooked starch with tris-beta-chloroethylamine.

A total of 50 g of acidic starch treated to reduce its viscosity to 85 on a scale of 100 with a water viscosity is suspended in 200 g of water and boiled for 20 minutes. The dispersion is cooled to 40 [deg.] C. and 550 g of water, 8 g of a 50% aqueous solution of sodium hydroxide and 4 g of tris-beta-chloroethylamine are added. The reaction is allowed to proceed for 9 minutes and then stopped by acidifying the mixture to pH 3 by adding hydrochloric acid. Paper samples are prepared using the additive of this example in an amount of 0.25% solids of the additive based on the weight of the solids in the pulp and the leaching and strength of the pigment is determined as described in Example II. The results of these experiments compared to the untreated sample and paper made using commercial cationic starch are summarized in Table IV.

15 571 1 7

Table IV

Pigment retention Mullen coefficient (%) at pH 7 * 5 (0.5% solids) _ Product of this example 51 1.71

Commercial Cationic Starch 60 1.76

Blind test 18 1.59

Example V

This example illustrates the preparation of cationic polysaccharide dispersions using phthalated hydrochloride condensates as derivatizing reagents.

Derivatizing reagents are prepared as follows: A. 1,6-Hexanediamine-epichlorohydrin condensate.

When mixed with about 100 parts of water in a vessel, 11.6 parts of 1,6-hexanediamine and 46.2 parts of epichlorohydrin are added dropwise at the same time while maintaining the temperature at about 50 ° C. After the addition is complete, the mixture is heated at 40 ° C with stirring for 5 hours. The resulting solution is concentrated to a solids content of 55-4% by evaporating the water at 50 ° C under reduced pressure.

B. Ethylenediamine-epichlorohydrin condensate.

As described in A, 6.0 parts of ethylenediamine and 37 parts of epichlorohydrin are condensed and the resulting solution is concentrated to a solids content of 59> 8%.

The derivatizing reagents prepared in A and B are reacted with polysaccharides as follows.

C. Potato starch (10 parts) is colloidally dispersed with sodium hydroxide (4 parts) in 990 parts of water. To this dispersion is added 0.6 part of 1,6-hexanediamine condensate prepared as described in A and the reaction is allowed to proceed for 5 hours at room temperature. The mixture is then acidified with hydrochloric acid to pH 4.5. The mixture contains 5.0% solids.

D. Acacia wood resin (high viscosity, 10 parts) is dispersed in 990 parts of water with 2 parts of sodium hydroxide. To this dispersion is added 0 * 6 parts of ethylenediamine-epichlorohydrin condensate prepared as described in B and the reaction is allowed to proceed at room temperature for 152 hours and at 40 ° C for 5 hours. The mixture is then acidified with dilute sulfuric acid to pH 4.5. The mixture contains 1.6% solids.

16 57117

Polysaccharide derivatives prepared as described in C and D are tested for their effectiveness as pigment retention agents as described in Example II. The results of these experiments, as well as the results obtained using a commercial pigment starch derivative retainer and a reference agent that does not contain any pigment retention agent, are shown in Table V. It can be seen that the pigment retention agents prepared according to this example give results comparable to those obtained with a commercial retention agent.

Table V

Retention agent Pigment retention C%) at pH 6TQ 73 ~

Item C product £ 3 3> 2

Product of section D 48 56

Commercial pigment retention agent 74 55

Blind test 40 7 · 5

Example VI

This example demonstrates the preparation of cationic derivatives of modified celluloses according to the invention.

10 parts of both methylated cellulose and hydroxypropylated cellulose are dispersed separately in 990 parts of water, and 4 parts of a 50% aqueous solution of sodium hydroxide are added to each dispersion. 0.6 part of the derivatizing reagent is then added to each dispersion and the reactions are allowed to proceed for 3 hours at room temperature. The reactions are stopped by acidifying the mixture to pH 4. The basic substances and reagents and the solids concentrations of the reaction mixtures are shown in Table VI.

Table VI

Substrate Reagent% solids

Condensation product of methylated cellulose N, N-dimethylpropanediamine and epichlorohydrin (molar ratio 1: 3) 1.9

Condensation product of hydroxypropylated Ν, Ν-dimethylpropanediamine and cellulose epichlorohydrin (molar ratio 1: 4) 2.2 17 5 71 1 7 The products obtained in these reactions are added to pulp and sampled and pigment retention and strength are determined according to Example II. In either case, the products made according to this example have better pigment retention and strength than paper made without using these products.

Instead of the above, any naturally occurring polymer of carbohydrates having a molecular weight greater than 10,000 can be used. Lower molecular weight materials can be used; however, larger amounts of derivatizing reagent are required. For this reason, the use of such substances is e-non-economic. Preferred polysaccharides are those having a molecular weight greater than 50,000.

In summary, the present invention provides novel flocculants and agents that improve paper strength and pigment retention and improved methods for making the same.

Claims (10)

A derivative of a water-dispersible polysaccharide for use as a flocculant, a pigment retention agent or a strength-enhancing agent, in particular in the manufacture of paper, characterized in that it is prepared by reacting a water-dispersible polysaccharide colloidally dispersed in an alkaline-alkaline aqueous solution. 160 ° C and at a concentration low enough to prevent agglomeration, with a non-polymeric derivatizing reagent having at least one cationic group and at least two functional groups capable of reacting with a water-dispersible polysaccharide, this reagent being an amine containing at least two a non-halohydrin-functional polysaccharide-reactive group, such as chlorine atoms or activated double bonds, a cyclic amine containing at least two polysaccharide-reactive groups a functional group, a condensation product of an amine and a polyamine with an aldehyde and a poly-aldehyde, or a formaldehyde-acetone-amine condensate. A derivative according to claim 1, characterized in that said polysaccharide is starch. A derivative according to claim 2, characterized in that the starch is reacted with said derivatizing reagent in a continuous digester at a temperature of about 80 to 160 ° C and a residence time in the digester of up to about 5 minutes. A derivative according to claim 1, characterized in that said derivatizing reagent is N-beta-chloroethyl-4- (3-chloropropyl) piperidine or tris-beta-chloroethylamine. A process for the derivative of a polysaccharide according to claim 1. for its preparation, characterized in that the water-dispersible polysaccharide is reacted colloidally dispersed in an aqueous alkaline solution, under alkaline conditions at a temperature of 25 to 160 ° C and at a concentration low enough to prevent the formation of agglomerates, with a non-polymeric derivatizing agent, at least one cationic group and at least two functional groups capable of reacting with a water-dispersible polysaccharide, said reagent being an amine containing at least two non-halohydrin functional groups reactive with the polysaccharides, such as chlorine atoms or activated double bonds, cyclic at least two functional groups reactive with polysaccharides, a condensation product of an amine and a polyamine with an aldehyde and a polyaldehyde, or a formaldehyde-acetone-amine condensate. A method according to claim 5, characterized in that said polysaccharide is starch. Process according to claim 6, characterized in that the starch is reacted with said derivatizing reagent in a continuous digester at a temperature of about 80 to 160 ° C and a residence time in the digester of at most about 5 minutes. Process according to Claim 5, characterized in that the reaction between the polysaccharide and the derivatizing agent is stopped by adding an acid to the reaction mixture so that the pH drops to 7 or below. Process according to claim 5, characterized in that said derivatizing reagent is N-beta-chloroethyl-4- (3-chloropropyl) piperidine or tris-beta-chloroethylamine. Process according to Claim 5, characterized in that the cross-linking inhibitor is also present in an amount of 1 to 15% by weight, based on said polysaccharide.