MX2008008274A - Sizing of paper - Google Patents

Abstract

The invention relates to an aqueous dispersion of cellulose-reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or quaternary ammonium thereof having a molecular weight less than 180 and/or having one or more hydroxyl groups. The invention further relates to a method for the preparation of an aqueous dispersion of cellulose-reactive sizing agent which comprises dispersing an acid anhydride in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or quaternary ammonium thereof having a molecular weight less than 180 and/or having one or more hydroxyl groups. The invention also relates to the use of the aqueous dispersion of cellulose-reactive sizing agent as a stock sizing agent or surface sizing agent in the production of paper. The invention further relates to a process for the production of paper which comprises adding the aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulosic suspension.

Description

PAPER LINING TECHNICAL FIELD This invention relates to the sizing of paper and more specifically to aqueous dispersions of cellulose-reactive sizing agent and their preparation and use.

BACKGROUND OF THE INVENTION Cellulose-reactive sizing agents such as those based on alkenyl succinic anhydride (ASA) are widely used in papermaking in a neutral or slightly alkaline pH buffer to give the paper and the board some degree of moisture resistance and penetration of aqueous liquids. Paper sizes based on cellulose-reactive sizing agents are generally provided in the form of dispersions containing an aqueous phase and finely divided particles or drops of the sizing agent dispersed therein. The dispersions are generally prepared with the aid of a dispersing system consisting of an anionic compound, for example sodium lignosulfonate, in combination with a high molecular weight or cationic enfoteric polymer, for example cationic starch, polyamide, polyamideamine or an addition polymer of vinyl.

WO 96/17127 discloses aqueous dispersions comprising a cellulose-reactive sizing agent and silica particles modified with colloidal anionic aluminum. WO 97/31152 describes aqueous dispersions comprising a reactive size and an anionic microparticulate material. The dispersions may also contain no more than 2% (by weight based on the weight of the reactive size) or surfactant. The surfactant may be non-anionic or anionic. WO 98/33979 A1 discloses an aqueous dispersion of the cellulose-reactive sizing agent and a dispersing system comprising a cationic organic compound and an anionic stabilizer. Despite the fact that considerable improvements have been made in the preparation, properties and performance of the aqueous dispersions of alkenyl succinic anhydride, there are still technical problems associated with the use of such dispersions. Generally, dispersions of alkenyl succinic anhydride show little stability, which obviously leads to difficulties in the handling of dispersions, for example in storage and in use. Another disadvantage is that the aqueous dispersions can not be stored for long periods because the alkenyl succinic anhydride is easily hydrolyzed and thus becomes ineffective as a sizing agent. Therefore, alkenyl succinic anhydride is generally supplied to the paper mills as a liquid, which is then dispersed before use as a sizing agent and the dispersion obtained is generally used in 2 hours to avoid the problems of insufficient stability and loss of sizing efficiency. The equipment used to prepare the dispersions provides high shear forces that will be able to establish free surfaces and produce dispersions having suitable particle sizes. Such equipment is generally complicated and expensive and due to its high shear forces it generally requires a considerable amount of energy. It is an object of this invention to provide an aqueous dispersion of cellulose-reactive sizing agent that can be easily prepared using low shearing forces and low energy consumption. Another objective of this invention is to provide an aqueous dispersion of cellulose-reactive sizing agent that exhibits improved stability and sizing efficiency. Other objectives will appear from here on.

BRIEF DESCRIPTION OF THE INVENTION The invention relates to an aqueous dispersion of cellulose-reactive sizing agent containing an anhydride acid, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or a quaternary ammonium thereof having a molecular weight of less than 180 and / or having one or more hydroxyl groups.

The invention also relates to a method for the preparation of an aqueous dispersion of cellulose-reactive sizing agent which comprises dispersing an anhydride acid in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or a quaternary ammonium thereof having a weight molecular lower than 180 and / or having one or more hydroxyl groups. The invention also relates to the use of the aqueous dispersion of cellulose-reactive sizing agent as a stock sizing agent or a surface sizing agent in the production of paper. The invention also relates to a process for the production of paper which comprises adding the aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulose suspension and dehydrating the suspension obtained in a cable as well as a process for the production of paper comprising apply the aqueous dispersion of cellulose-reactive sizing agent to a cellulose network.

DETAILED DESCRIPTION OF THE INVENTION In accordance with this invention it has been found that improved paper sizing can be achieved by using this aqueous dispersion of cellulose-reactive sizing agent. It has also been found that these dispersions show better stability over conventional dispersions.

In addition, it has been found that the lower shear forces can be used to prepare these aqueous dispersions compared when preparing the conventional aqueous dispersions of cellulose-reactive sizing agent. By means of this, the invention makes it possible to use energy and equipment that saves the investment by creating low shear forces such as for example static mixers. Therefore, this invention offers substantially economic and technical benefits. The cellulose-reactive sizing agent according to the invention can be selected from any sizing agent based on anhydride acid known in the art. Suitably, the sizing agent is a hydrophobic anhydride acid. Suitable hydrophobic anhydride acids can be characterized by the following general formula (I), wherein R1 and R2 are independently selected from the saturated or unsaturated hydrocarbon groups which suitably contain from 8 to 30 carbon atoms, or R1 and R2 together with the -COC- portion they can form a ring of 5 to 6 elements optionally substituted with hydrocarbon groups containing above 30 carbon atoms.

(I) o or II II R '- C - O - C - R " Examples of suitable anhydride acids include alkyl and alkenyl succinic anhydrides, for example iso-octadecenyl succinic anhydride, iso-octadecyl succinic anhydride, n-hexadecenyl succinic anhydride, dodecenyl succinic anhydride, decenyl succinic anhydride, octhenylsuccinic anhydride, tri-isobutenyl succinic anhydride , 1-octyl-2-decenylsuccinic anhydride and 1-hexyl-2-octenyl-succinic anhydride. Examples of suitable anhydride acids further include the compounds described in the U.S. Patents. No. 3,102,064; 3,821, 069; 3,968,005; 4,040,900; 4,522,686; and Re. 29,960, which are incorporated herein by reference. The cellulose-reactive sizing agent according to the invention may contain one or more anhydride acids, for example one or more alkyl and / or alkenyl succinic anhydrides. Generally, the anhydride acid of this invention is liquid at room temperature. The dispersion according to the invention contains a dispersant or a dispersing system comprising an anionic polyelectrolyte and an organic compound containing nitrogen. When used in combination, these compounds are effective as a dispersant for the anhydride acid sizing agent although the anionic polyelectrolyte and the nitrogen-containing organic compound can not be effective as a dispersant when used separately. Preferably, the dispersion is anionic ie the dispersant or dispersant system has a total anionic charge. The anionic polyelectrolyte according to the invention can be selected from organic and inorganic compounds and can be derived from natural or synthetic sources. The anionic polyelectrolyte has two or more anionic groups which may be of the same or different types. Examples of suitable anionic groups, ie, groups that are anionic or anionic in an aqueous phase, include silanol, aluminosilicate, phosphate, phosphonate, sulfate, sulfonate, sulfonic and carboxylic acid groups as well as salts thereof, generally ammonium or alkaline mental salts (usually sodium). The anionic polyelectrolytes can be water-soluble, for example linear or branched anionic polyelectrolytes, or dispersible in water, for example by crosslinked and / or particulate anionic electrolytes. Preferably, the water dispersible anionic polyelectrolytes and particulates are colloidal, that is, on the colloidal scale of the particle size. The colloidal particles suitably have a particle size of 1 nm to 100 nm, preferably 2 to 70 nm and more preferably 2 to 40 nm. The anionic polyalectrolytes dispersible in water and particulates may contain aggregated and / or non-aggregated particles. Examples of suitable organic anionic polyelectrolyte include anionic polysaccharides, such as starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gum, mannans and dextrins. Other examples of suitable organic anionic polyelectrolytes include synthetic anionic polymers such as condensation polymers, for example polyurethanes and naphthalene-based and melamine-based polymers, for example condensed naphthalene formaldehyde sulfonates and polymers with melamine sulphonic acid base, and vinyl addition polymers prepared from ethylenically unsaturated monomers including anionic or potentially anionic monomers, for example acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, vinylsulfonic acid, sulfonated styrene and hydroxyalkyl acrylate and methacrylate phosphates , optionally copolymerized with non-anionic ethylenically unsaturated monomers, for example acrylamide, alkyl acrylates, styrene and acrylonitrile as well as derivatives of such monomers, vinyl esters and the like. Examples of other suitable organic anionic polyelectrolyte include water-soluble branched polymers and water-dispersible crosslinked polymers obtained by polymerization of a monomer mixture comprising one or more ethylenically unsaturated or potentially anionic anionic monomers and optionally one or more ethylenically unsaturated monomers in the presence of 1 or more polyfunctional interlacing agents. The presence of a polyfunctional crosslinking agent in the monomer mixture results in the possible preparation of branched polymers, lightly entangled polymers and highly entangled polymers which are dispersible in water. Examples of suitable polyfunctional crosslinking agents include compounds having at least two ethylenically unsaturated bonds, for example N, N-methylene-bis- (meth) acrylamide, polyethylene glycol di (meth) acrylate, N-vinyl (meth) acrylamide, divinyl -benzene, triallylammonium salts and N-methylallyl (meth) acrylamide, compounds having an ethylenically unsaturated bond and a reactive group, for example, glycidyl (meth) acrylate, acrolein and methylol (meth) acrylamide, and compounds having less two reactive groups for example dialdehydes such as glyoxal, diepoxy compounds and epichlorohydrin. The organic anionic polyelectrolyte generally has an anionic substitution degree (DSA) of 0.01 to 1.4, suitably 0.1 to 1.2 and preferably 0.2 to 1.0. The anionic polyelectrolyte may contain one or more cationic groups while having a total anionic charge. The molecular weight of the anionic polyelectrolyte can vary within broad scales; generally, the molecular weight is above 200 and suitably above 500, while the upper limit is generally 10 million and preferably 2 million. Examples of suitable inorganic anionic polyelectrolyte include anionic siliceous materials, for example silicon-based anionic materials prepared from silicic acid and smectite-type clays. Generally, these anionic polyelectrolytes have negative silanol, aluminosilicate or hydroxyl groups. Examples of suitable inorganic anionic polyelectrolyte include polysilicic acid, polysilicates, polyaluminiosilicates, silica-based colloidal particles eg silica particles, alumina silica (modified with aluminum) and aluminosilicate, polysilicate microgels, polyaluminiosilicate microgels, silica gels and silica precipitate, smectite clays, for example, montmorillonite, bentonite, hectorite, beidelite, nontronite and saponite. Preferred anionic polyelectrolytes include silica-based materials for example colloidal particles with silica base.

The organic nitrogen-containing compound according to the invention is an amine or a quaternary ammonium thereof. Nitrogen-containing organic compounds include primary, secondary and tertiary amines and quaternary ammoniums thereof. Further suitable nitrogen-containing organic compounds include monoamines, diamines and polyamides and quaternary ammoniums thereof. Quaternary ammoniums include protonated, alkylated, arylated, and alkylated amines or the aforementioned types which can be made by the reaction of amines with, for example, acids, for example hydrochloric acid and methyl chloride, dimethisulfate and benzyl chloride. In a preferred embodiment of the invention, the nitrogen-containing organic compound is an amine or a quaternary ammonium thereof having one or more hydroxyl groups. Preferably one or more hydroxyl groups are present in a terminal position of one or more substituents of the nitrogen-containing compound that is a finished hydroxyl group amine or a quaternary ammonium thereof. Examples of suitable nitrogen-containing organic compounds include the following amines and their quaternary ammoniums: diethylenetriamine, triethylenetetramine, hexamethylenediamine, diethylamine, dipropylamine, diisopropylamine, cyclohexylamine, pyrrolidine, guanidine, triethanolamine, monoethanolamine, diethanolamine, 2-methoxyethylamine, aminoethylethanolamine, alanine and lysine Other examples of suitable nitrogen containing organic compounds include choline hydroxide, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide. Preferred nitrogen-containing organic compounds include triethanolamine and quaternary ammoniums thereof. The molecular weight of the nitrogen-containing organic compound can vary within wide limits. In a preferred embodiment of the invention, the molecular weight of the amine or quaternary ammonium thereof is less than 180, suitably above 170 and preferably above 160. The molecular weight is generally at least 30. As mentioned herein, the The molecular weight of a quaternary ammonium of an amine means the molecular weight of the cationic part of the quaternary ammonium compound which means that the anionic part of the quaternary ammonium compound is not included in the molecular weights given above. For the nitrogen-containing organic compounds that are selected from amine and quaternary ammoniums thereof having one or more hydroxyl groups, the molecular weights may be higher, for example less than 500 and generally less than 300, although the aforementioned molecular weights they are also suitable for such compounds. In this aqueous dispersion, or emulsion, the anhydride acid may be present in an amount of from about 0.1 to about 50% by weight, suitably from 0.1 to about 30% by weight and preferably from about 1 to about 20% by weight, with based on the weight of the aqueous dispersion. The anionic polyelectrolyte is generally present in an amount above about 100% by weight, generally from 0.1 to 15% by weight suitably from 0.5 to 10% by weight and preferably from 1 to 7% by weight based on the weight of the anhydride acid . The nitrogen-containing organic compound may be present in an amount above 20% by weight, generally from 0.1 to 15% by weight, suitably from 0.5 to 10% by weight and preferably from 1 to 7% by weight based on the weight of anhydride acid. In addition to the anhydride acid, the anionic polyelectrolyte and the nitrogen-containing organic compound, optional additional compounds may be present in the dispersion. Examples of such compounds include mono-, di- and poly-anionic and non-anionic surfactants and dispersing agents, stabilizers, extenders and preserving agents such as, for example, hydrolyzed anhydride acids, for example, alkyl and alkenyl anhydrides hydrolyzed as it was mentioned above, preferably hydrolyzed alkenyl succinic anhydrides, for example anhydride acids hydrolyzed in the carboxylic acid form and / or carboxylic acid ester derivatives, anionic surfactants such as phosphate esters, such as ethoxylated phosphate esters, alkyl sulfates, sulfonates and phosphates, alkylarylsulfates , sulfonates and phosphates, for example sodium lauryl sulphonate and ethoxylated phosphate isotridecylalcohol. If present, the content of such additional compounds in the dispersion may be from 0.1 to 15% by weight, suitably from 1 to 10% by weight and preferably from 2 to 7% by weight based on the weight of the anhydride acid. Water is also present in the dispersion and can constitute the remainder of the dispersion above 100% by weight.

The dispersion according to the invention can be produced by forming a mixture containing the anhydride acid, the anionic polyelectrolyte and the nitrogen-containing organic compound as defined above and dispersing the mixture in the presence of water. The components of the dispersion can be mixed in any order but preferably the anionic polyelectrolyte and the organic compound containing hydrogen are mixed and diluted with water to the appropriate concentration and then the anhydride acid is dispersed therein. The mixture can be dispersed by using suitable dispersing equipment that provides a sufficient degree of dispersion, for example a static mixer that provides relatively low shear force. The obtained dispersion contains drops of anhydride acid generally having a size of 0.1 to 10 μm. The aqueous dispersions according to the invention can be used conventionally in the production of paper using any type of cellulosic fiber and can be used for both surface bonding and internal sizing. The term "paper", as used herein, means including not only paper, but all types of cellulosic products in the form of a sheet and network including, for example, cardboard and cardboard. The cellulosic suspension and the finished paper may also contain mineral fillers and generally the cellulose fiber content is at least 50% by weight based on the dry cellulosic suspension or the finished paper. Examples of mineral fillers of conventional types include kaolin, china clay, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as chalk, earth marble, and precipitated calcium carbonate. This invention also relates to a process for the production of paper in which the aqueous sizing dispersion is added to an aqueous cellulosic suspension or applied to a cellulose sheet or network. Suitably, the amount of cellulose-reactive sizing agent is added to the cellulosic suspension to be drained in a cable to form paper, or applied to the surface of a cellulosic sheet or web as a surface size generally in the size pressure that is 0.01 to 1.0% by weight based on the dry cellulosic suspension and optional fillers, preferably 0.05 to 0.5% by weight where the dose is mainly dependent on the quality of the pulp or paper to be glued and the level of desired gluing. The aqueous sizing dispersions according to the invention are particularly useful in the production of paper from an aqueous cellulosic suspension having a high conductivity. The conductivity of the suspension that dehydrates in the cable can be within the range of 0.3 mS / cm to 10 mS / cm. According to this invention, good results can be achieved when the conductivity is at least 2.0 mS / cm, notably at least 3.5 mS / cm, particularly at least 5.0 mS / cm and even at least 7.5 mS / cm. The conductivity can be measured by standard equipment such as for example a WTW LF 330 instrument provided by Christian Berner. The aforementioned values are suitably determined by measuring the conductivity of the cellulosic suspension that is fed into or present in the drawer of the paper machine or alternatively by measuring the conductivity of the white water obtained by dehydrating the suspension. The high levels of conductivity mean high contents of salts (electrolytes) which can derive from the materials used to form the reserve, from several additives introduced into the reserve, from the fresh water supplied to the process, etc. In addition, the salt content is generally higher in procedures where white water recirculates excessively, which can lead to considerable accumulation of salts in the water circulating in the process. Chemicals conventionally added to the cellulose suspension in papermaking such as retention substances, aluminum compounds, dyes, moisture resistant resins, optical brighteners etc., can be used in conjunction with this dispersion. Examples of aluminum compounds include alum, aluminates, and polyaluminum compounds, for example chlorides and polyaluminium sulfates. Examples of suitable retention substances include cationic polymers, anionic inorganic materials in combination with organic polymers, for example bentonite in combination with cationic polymers, silica-based solutions in combination with cationic polymers or cationic and anionic polymers. Particularly, good sizing can be obtained when the dispersion of the invention is used in combination with retention substances comprising cationic polymers. Suitable cationic polymers include cationic starch, acrylate-based and acrylamide-based polymers, polyethylene imine, polyamines, polyamidoamines and poly (diallyldimethyl ammonium chloride) and combinations thereof. Preferred retention substances include cationic starch and cationic polymers based on acrylamide. In a preferred embodiment of the invention, the dispersions are used in combination with a retention system comprising at least one cationic polymer and an anionic siliceous material, for example particles with a silica or bentonite base. It is possible to pre-mix one or more components of this dispersion with a retention substance, for example an anionic siliceous material, before introducing the obtained mixture into the cellulose suspension. Accordingly, this aqueous sizing dispersion can be prepared just before it is introduced into the cellulosic suspension by contacting the anhydride acid and the nitrogen-containing organic compound with an anionic polyelectrolyte such as, for example, an aqueous siliceous material, for example a solution based on silica or bentonite suspension. The invention is also illustrated in the following examples, which however are not intended to limit the same. Parts and% refer to parts by weight and% by weight, respectively, unless otherwise indicated.

EXAMPLE 1 The aqueous dispersions according to the invention are prepared by dispersing alkenyl succinic anhydride (ASA) based on an olefin fraction comprising iso-hexadecenyl and iso-octadecenyl succinic anhydride in the presence of a mixture of anionic polyelectrolyte and amine in a mixer static tube Hash. The aqueous dispersions used for comparison in this and other examples were prepared in a similar manner except that no amine, non-colloidal silica, high molecular weight amines and / or amines not having hydroxyl groups were used. The anionic polyelectrolyte used in this example was colloidal silica (Eka NP 590) in the form of an aqueous solution having an SiO2 content of 8.1% by weight and containing silica particles with a specific surface area of 850 m2 / g which was modified by aluminum. The amine used in this example was triethanolamine (TEA) having a molecular weight of 149. The anionic polyelectrolyte and the amine were mixed in the presence of water to form a mixture which was pumped at one end of the tube in a flow of 3.17. l / min, and the concentrated ASA was pumped from the side of the tube at a flow of 0.167 l / min. The pressure fell on the mixing unit which was 3.4 bar. The dispersion obtained had an ASA content of 5% by weight, anionic polyelectrolyte content (in this example, S02 content) of 5.0% by weight based on the ASA and the amine content ranging from 0 to 2.0. % by weight based on the ASA. Dispersions 1 to 4 were prepared as shown in Table 1 in which the SiO2 and the given amine contents were based on ASA. TABLE 1 The particle size of the ASA droplets was measured in a Malvern Mastersizer Microplus after dissolution of the dispersions with water at an ASA content of 0.5% by weight. The results are shown in table 2. (D (v 0.1), D (v 0.5), D (v 0.9) means that 10, 50 and 90% of the particles respectively had a smaller diameter than the given size.

TABLE 2 As can be seen from Table 2, the dispersions according to this invention, dispersions No. 2 to 4, resulted in smaller particle sizes on the dispersion used for the comparison, dispersion number 1. The sizing efficiency was evaluated when preparing sheets of paper made by hand according to the standard method SCAN-C26: 76 and the gluing was measured as Cobb-60 values according to the Tappi standard method T441. The paper sheets were prepared according to a process in which the dispersions were added to an aqueous cellulosic suspension comprising recycled pulp having a fiber concentration of 0.5 g / l, conductivity of 0.7 mS / cm and pH around 7.0 . The dispersions were added in amounts of 0.5, 1.0 and 1.5 kg / t, calculated as ASA and based on the weight of the dry cellulose suspension. A retention system was used comprising 6 kg / t of cationic potato starch (Perlbond 970) and 0.5 kg / t of silica solution (Eka NP 442), calculated as dry substances in dry cellulose suspension. The Cobb-60 values were measured and the results are presented in Table 3. The lower Cobb values mean that a smaller amount of water was absorbed and therefore a better gluing was achieved.

TABLE 3 As can be seen from Table 3, the dispersions according to the invention, dispersions number 2 to 4 resulted in an improved sizing efficiency on the dispersion used for comparison, dispersion number 1.

EXAMPLE 2 The dispersions were prepared and the sizing efficiency of the dispersion was evaluated according to the general procedures of Example 1, except that the variant contents of silica were used and the amine content was constant. The dispersions had an ASA content of 5% by weight, based on the weight of the dispersion. Table 4 shows the results.

TABLE 4 As can be seen from Table 4, the dispersions according to the invention, dispersions number 6 to 9, resulted in improved sizing efficiency on the dispersion used for the comparison, dispersion No.5.

EXAMPLE 3 The dispersions were prepared and evaluated according to the general procedures of Example 1. Comparisons of the dispersions were made in aqueous cellulose suspensions having increased conductivity upon addition of calcium chloride. The conductivity of the suspensions was measured by using a WTW LF 330 instrument from Christian Berner. The results were presented in table 5.

TABLE 5 As can be seen from table 5, the dispersion according to the invention, dispersion No. 11, showed sizing efficiency considerably better than the dispersion used for the comparison, dispersion No. 10 when the conductivity of the suspension increased.

EXAMPLE 4 The dispersions were prepared and matched according to the general procedures of Example 1 except that different amines were used. The dispersion obtained had an ASA content of 5% by weight, Si02 content of 5.0% by weight based on the ASA, and the content of amine of 2.0% by weight based on the ASA. The amines used were triethanolamine (TEA) having a molecular weight of 149, diethylenetriamine (DETA) having a molecular weight of 103, a coconut fractionated fatty amine (FCA) having a molecular weight of about 200 and a dimethylammonium chloride with dihydrogenated tallow (DTDMAC) having a molecular weight of approximately 530. The particle sizes are presented in Table 6.

TABLE 6 The results of the sizing efficiency evaluated are shown in table 7.

TABLE 7 As can be seen from tables 6 and 7, the dispersions according to this invention, number dispersions. 14 and 15 which contained amine having a molecular weight less than 180 (dispersion No. 14 and 15) and having hydroxyl groups (dispersion No. 15), resulted in smaller particle sizes and considerably improved sizing efficiency over the dispersions used for comparison, dispersion no. 12 and 13. This also means that less energy was required to establish the free surfaces according to the invention.

EXAMPLE 5 The dispersions were prepared and evaluated according to the general procedures of Example 1 except that different anionic polyelectrolytes were used. The dispersion obtained had an ASA content of 5% by weight, SiO2 content of 5.0% by weight based on the ASA, and content of triethanolamine 0 or 2.0% by weight based on the ASA. The anionic polyelectrolytes used are shown in table 8.

TABLE 8 The bentonites were packed in water (5% by weight of bentonite) were stored for 5 days to achieve sufficient inflammation and separation. The particle size was determined and the stability was evaluated.

The stability was measured 2 hours after the preparation. If it remains stable after 24 hours, the particle size will be determined again. The term "sep" means separation. The results are shown in table 9.

TABLE 9 The results of the evaluation of the sizing efficiency were shown in table 10 TABLE 10 As can be seen from tables 9 and 10, the dispersions according to this invention, dispersions No.17, 19, 21, 23 and , which contained both anionic polyelectrolyte and nitrogen-containing organic compound, showed better sizing efficiency, better stability and resulted in smaller particle size over the dispersions used for the comparison of dispersion numbers 16, 18, 20, 22 and 24 which it was contained by the organic compound that contains nitrogen.

EXAMPLE 6 The dispersions were prepared and the particle size and sizing efficiency of the dispersions were evaluated according to the general procedures of Example 1, except that different surfactants and varied contents of surfactants were used. The polyelectrolyte used was colloidal silica (Eka NP 780) in the form of an aqueous solution having an SiO2 content of 7.5% by weight and containing silica particles with a specific surface area of approximately 900m2 / g and which was modified by aluminum. The amine used was triethanolamine (TEA). The dispersion obtained had an ASA content of 5% by weight, Si02 content of 5.0% by weight based on the ASA and the content of amine of 2.0% by weight, based on the ASA. No surfactant was incorporated in the dispersion number 26. The hydrolyzed ASA was incorporated as a surface active agent in the dispersion numbers 27 and 28. The surfactant used in the dispersion number 29 was a phosphate ester. (poly (oxy-1, 2-ethanediyl) alpha-isotridecyl-omega-hydroxyphosphate). The surfactant contents in the dispersions were based on the ASA. The results of the particle size measurements are shown in table 11.

TABLE 11 The sizing efficiency of the dispersions was evaluated and comparisons of the dispersions were made in an aqueous cellulose suspension comprising 70% pulp (80/20 birch / pine manufacture) and 30% filler (CaCo3).

TABLE 12 As can be seen from the results presented in Tables 11 and 12, the dispersion numbers 27, 28 and 29 containing a surfactant resulted in a smaller particle size and showed a better sizing efficiency than the dispersion which does not contain surfactant agent.

EXAMPLE 7 The dispersions of Example 6 were evaluated in terms of the sizing efficiency when using aqueous cellulosic suspensions comprising unbleached manufacturing pulp having varied conductivities. The results were shown in table 13.

TABLE 13 As can be seen from Table 13, the dispersion numbers 27, 28 and 29 containing a surfactant showed better sizing efficiency than the dispersion containing no surfactant, dispersion number 26.

Claims (9)

NOVELTY OF THE INVENTION CLAIMS

1. An aqueous dispersion of cellulose-reactive sizing agent containing an anhydride acid, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or a quaternary ammonium thereof having a molecular weight of less than 180.

2.- One aqueous dispersion of cellulose-reactive sizing agent containing an anhydride acid, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or a quaternary ammonium thereof having one or more hydroxyl groups.

3. A method for the preparation of an aqueous dispersion of cellulose-reactive sizing agent which comprises dispersing an anhydride acid in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or a quaternary ammonium thereof having a molecular weight less than 180.

4. A method for the preparation of an aqueous dispersion of cellulose-reactive sizing agent which comprises dispersing an anhydride acid in an aqueous phase in the presence of an anionic polyelectrolyte and an organic nitrogen-containing compound which is an amine or a quaternary ammonium thereof having one or more hydroxyl groups.

5. - The aqueous dispersion according to any of claims 1 and 2 or the method according to any of claims 3 or 4, further characterized in that the nitrogen-containing compound has a molecular weight above 170. 6.- The aqueous dispersion according to any one of claims 1, 2 and 5 or the method according to any of claims 3 to 5, further characterized in that the nitrogen-containing compound has a molecular weight above 160. The aqueous dispersion of according to any of claims 1, 2, 5 and 6 or the method according to any of claims 3 to 6, further characterized in that the nitrogen-containing compound has one or more hydroxyl groups. 8. The aqueous dispersion according to claim 7 or the method according to claim 7, further characterized in that one more hydroxyl groups are present in a terminal position of one more substituents of the nitrogen-containing compound. 9. The aqueous dispersion according to any of claims 1, 2 and 5 to 8, the method according to any of claims 3 to 8, further characterized in that the nitrogen-containing compound is an amine. 10. The aqueous dispersion according to any of claims 1, 2 and 5 to 8, or the method according to any of claims 3 to 8, further characterized in that the nitrogen-containing compound is a quaternary ammonium. 11. The aqueous dispersion according to any of claims 1, 2 and 5 to 10, or the method according to any of claims 3 to 10, further characterized in that the nitrogen-containing compound is diethylene triamine, triethylene tetramine, hexamethylenediamine, diethylamine, dipropylamine, di-isopropylamine, cyclohexylamine, pyrrolidine, guanidine, triethanolamine, monoethanolamine, diethanolamine, 2-methoxyethylamine, aminoethylethanolamine, alanine, lysine, choline hydroxide, tetramethyl ammonium hydroxide or tetraethyl ammonium hydroxide. 12. The aqueous dispersion according to any of claims 1, 2 and 5 to 11, or the method according to any of claims 3 to 11, further characterized in that the anionic polyelectrolyte is an inorganic material. 13.- The aqueous dispersion in accordance with the claim 12, or the method according to claim 12, further characterized in that the anionic polyelectrolyte is a siliceous material. 14. The aqueous dispersion in accordance with the claim 13, or the method according to claim 13, characterized in that the anionic polyelectrolyte is bentonite. 15. The aqueous dispersion according to claim 13, or the method according to claim 13, further characterized in that the anionic polyelectrolyte comprises silica-based particles. 16. The aqueous dispersion according to any of claims 1, 2 and 5 to 15, or the method according to any of claims 3 to 15, further characterized in that the anhydride acid is iso-octadecenyl succinic anhydride, isohydrate iso -octadecyl succinic, n-hexadecenyl succinic anhydride, dodecenyl succinic anhydride, decenyl succinic anhydride, octenyl succinic anhydride, tri-isobutenyl succinic anhydride, 1-octyl-2-decenyl-succinic anhydride or 1-hexyl-2-octenyl-succinic anhydride . 17. The aqueous dispersion according to any of claims 1, 2 and 5 to 16, or the method according to any of claims 3 to 16, further characterized in that the anhydride acid is present in an amount of 0.1 to 30. % by weight, based on the weight of the aqueous dispersion. 18. The aqueous dispersion according to any of claims 1, 2 and 5 to 17, or the method according to any of claims 3 to 17, further characterized in that the anionic polyelectrolyte is present in an amount of 0.5 to 10. % by weight based on weight of the anhydride acid. 19. The aqueous dispersion according to any of claims 1, 2 and 5 to 18, or the method according to any of claims 3 to 18, further characterized in that the organic compound containing nitrogen is present in an amount of 0.5 to 10% by weight based on the weight of the anhydride acid. 20. The aqueous dispersion according to any of claims 1, 2 and 5 to 19, or the method according to any of claims 3 to 19, further characterized in that the dispersion further comprises an anionic surfactant, 21.- The aqueous dispersion in accordance with the claim 20 or the method according to claim 20, further characterized in that the anionic surfactant is hydrolyzed anhydride acid. 22. The use of the aqueous dispersion of the cellulose-reactive sizing agent of any of claims 1 to 21 for internal sizing or surface sizing in the production of paper. 23. A process for the production of paper which comprises adding an aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulose suspension and dehydrating the suspension obtained in a cable or by applying an aqueous dispersion of cellulose-reactive sizing agent to the The surface of a cellulose sheet or network wherein the dispersion is an aqueous dispersion of cellulose-reactive sizing agent of any of claims 1 to 21. 24.- The process according to claim 23, further characterized in that the aqueous cellulosic suspension has a conductivity of at least 2.0 mS / cm.