KR20000070620A - Sizing of paper - Google Patents

Abstract

The invention relates to the use of an aqueous sizing dispersion containing a cellulose-reactive sizing agent and a hydrophobically modified dispersing agent for sizing cellulosic fibres by addition of the sizing dispersion to a stock containing cellulosic fibres, and optional fillers, and dewatering the stock on a wire to obtain a web containing cellulosic fibres, wherein the stock has a cationic demand of at least 50 mu eq/litre stock filtrate. The invention further relates to an aqueous dispersion containing a cellulose-reactive sizing agent and an anionic hydrophobically modified cellulose-derivative, its preparation and use in the production of paper. The invention also relates to a substantially water-free composition containing a cellulose-reactive sizing agent and an anionic hydrophobically modified cellulose-derivative, its preparation and use in the preparation of an aqueous dispersion of cellulose-reactive sizing agent.

Description

Paper Sizing Dispersion {SIZING OF PAPER}

Cellulose-reactive sizing agents based on alkyl ketene dimers (AKD) and alkenyl succinic anhydrides (ASA) are made from paper at paper or paper board at pH of neutral or weakly alkaline raw materials to provide resistance to wetting and penetration by aqueous liquids. Widely used in the process. Paper sizing dispersions based on cellulose-reactive sizing agents are generally provided in the form of dispersions containing an aqueous phase and finely divided particles or droplets in which the sizing agent is dispersed. This dispersion is usually prepared using a dispersant system composed of an anionic compound such as sodium lignosulfate in combination with a high molecular weight cation or amphoteric polymer such as cationic starch, polyamine, polyamideamine or vinyl addition polymer. Depending on the total charge of the dispersant system compound, the sizing dispersion is cationic or anionic.

Cellulose reactive sizing agents provide good sizing effects with low sizing agent administration. However, it has been observed that conventional cellulose reactive sizing agents have a high cation requirement and their efficiency decreases when used in raw materials comprising significant amounts of lipophilic wood extracts such as resin acids, fatty acids, fatty esters, triglycerides. Because of the anionic nature of lipophilic materials, including carboxylate or carboxylic acid groups, raw materials containing significant amounts of lipophilic extracts have fairly high cation requirements. It has been found that lipophilic materials can interfere with the fibrous adsorption of sizing agents and can result in poor sizing results. To improve the sizing effect on these raw materials, the papermaker had to increase the sizing agent dose, which is economically disadvantageous and can increase the accumulation of sizing agent in the white water recycled in the papermaking process. This problem is even greater in paper processes where white water is recycled excessively into the process with the introduction of a small amount of fresh water, further increasing the cation demand and further increasing the accumulation of lipophilic extracts and unmaintained sizing agents in white water and dewatering agents to be dehydrated. Serious.

Accordingly, it is an object of the present invention to improve the sizing effect and to improve the cellulose sizing agent dispersion when the cellulose reactive sizing agent dispersion is used in cellulose raw materials having high cation demand or high lipophilic extract or excessive white water recycling process. To provide water.

The present invention relates to paper sizing dispersions, in particular aqueous products containing cellulose-reactive sizing agents and hydrophobic modified dispersants, their preparation and use.

According to the present invention, it has been found that the sizing effect is improved by using an aqueous dispersion of cellulose reactive sizing agents having a hydrophobic modified dispersant in an internal sizing composition of a raw material having a high cation demand or containing a high content of lipophilic material. It has also been found that the sizing effect can be improved by using such dispersions in papermaking processes where the white water is recycled excessively to produce high cation demand or high lipophilic extract conditions. Therefore, the present invention provides a cellulose reactive sizing agent and a hydrophobic agent to an internal sizing composition of a raw material that is difficult to size by adding a sizing dispersion to a raw material containing cellulose fiber and auxiliary filler and obtaining dehydrated raw material on a wire to obtain a cellulose fiber-containing raw material or paper. It relates to the use of aqueous sizing dispersions containing modified dispersants. In a first aspect of the invention, the feed has a cation demand of at least 50 μeq / liter of feed filtrate. In a second aspect of the invention the raw material has a lipophilic material content of at least 10 ppm. A third aspect of the invention includes dewatering raw materials on a wire to obtain white water and cellulose fiber-containing webs, recycling white water, and supplementally introducing fresh water to form cellulose fiber-containing raw materials to be dehydrated. The amount of fresh water added is less than 30 tonnes per tonne of dry cellulose product produced. The present invention therefore relates to the use of an aqueous sizing dispersion containing a cellulose reactive sizing agent and a hydrophobically modified dispersant in a cellulose fiber sizing process.

In a preferred embodiment of the present invention the aqueous dispersions comprise cellulose reactive sizing agents and anionic hydrophobically modified dispersants, in particular anionic hydrophobically modified cellulose derivatives, and are also related to such dispersions and methods for their preparation. The dispersions provide improved stability and sizing properties and are particularly useful for refining materials that contain hydrophilic materials with high white water closure and have high cation demands.

The present invention produces paper with improved sizing properties compared to conventional sizing dispersions at similar cellulose reactive sizing agent dosages and allows the use of lower doses of cellulose reactive sizing agents to achieve similar levels of sizing effect. . The possibility of using a smaller amount of sizing agent to achieve the specified sizing effect reduces the risk of agglomeration and sedimentation of the sizing agent on the paper machine by reducing the risk of accumulation of nonadsorbed sizing agent in the white water recycled in the process. The present invention therefore provides economic and technical advantages.

The cellulose reactive sizing agent according to the present invention may be selected from cellulose reactive sizing agents known in the art. The sizing agent may be selected from hydrophobic ketene dimers, ketene multimers, acid anhydrides, organic isocyanates, carbamoyl chlorides or mixtures thereof, in particular ketene dimers and acid anhydrides, even more ketene dimers. Suitable ketene dimers have the general formula (1), wherein R ¹ and R ² are saturated or unsaturated hydrocarbons, usually saturated hydrocarbons, hydrocarbons having 8 to 36 carbon atoms and especially 12 to 20 carbon atoms, such as hexadecyl or octadecyl Linear or branched alkyl groups. Suitable acid anhydrides have the formula (2), wherein R ³ and R ⁴ are saturated or unsaturated hydrocarbons containing 8 to 30 carbon atoms or R ³ and R ⁴ are further substituted with hydrocarbons containing up to 30 atoms together with the -COC moiety. 5 to 6 transforms can be formed. Examples of commercially available acid anhydrides are alkyl and alkenyl succinic anhydrides, in particular isooctadecenyl succinic anhydride.

Suitable ketene dimers, acid anhydrides and organic isocyanates include compounds disclosed in US Pat. No. 4,522,686. Examples of suitable carbamoyl chlorides are disclosed in US Pat. No. 3,887,427.

In addition to the cellulose reactive sizing agent, the sizing dispersion may comprise a non-cellulose reactive sizing agent. Sizing agents of this type include fortified or esterified rosin, waxes, fatty acids, fatty acid derivatives such as fatty amides and fatty esters such as glycerol triesters of natural fatty acids.

Dispersions used according to the invention include hydrophobically modified dispersants, ie dispersants having one or more hydrophobic groups. Hydrophobic groups are attached to the dispersant in the form of hydrophobic side chains. Suitable hydrophobic groups are hydrophobic substituents containing at least 4, in particular at least 6, even more than 8 to 30 carbon atoms, in particular hydrophobic amides, esters and ethers comprising at least 4, especially at least 6, even 8 to 30 carbon atom containing saturated or unsaturated hydrocarbons. And a group containing a heteroatom such as oxygen or nitrogen or a heteroatom such as carbonyl or acyloxy. This dispersant may have a hydrophobic substitution (DS _H ) of 0.01 to 0.8, in particular 0.02 to 0.5, even 0.03 to 0.4.

Hydrophobically modified dispersants are charged or uncharged, in particular charged and contain one or more of the same or different kinds of ions. Ions are cations or anions. The dispersant is therefore cationic, anionic or amphoteric, in particular amphoteric or anionic, even more anionic. Suitable anionic groups include carboxyl, sulfone, phosphoric and phosphoric acid groups which may exist as sulfate groups and free acid or water soluble ammonium or alkali metal (generally sodium) salts such as sodium carboxylate and sulfonate. This dispersant may have a wide range of ionic substitution, with anion substitution (DS _A ) of 0.01 to 1.4, in particular 0.1 to 1.2, even 0.2 to 1.0. The cation substitution degree (DS _C ) is 0.01 to 1.0, in particular 0.1 to 0.8, even 0.2 to 0.6.

This dispersant is derived from synthetic or natural substances and is water soluble or water dispersible. Suitable dispersants include starch, guar gum, cellulose, chitin, chitosan, glycan, galactan, glucan, xan gum, mannan, dextrins, in particular starch, guar gum and cellulose derivatives, in particular anionic and cationic derivatives, even more phosphorylation, Hydrophobically modified polysaccharides such as sulfonated and carboxylated polysaccharides; Hydrophobically modified polymeric condensation products such as anionic and cationic polyurethanes, cationic polyamidoamines; Hydrophobically modified anionic and cationic vinyl addition polymers such as acryl (methacryl) amides, acryl (methacryl) lates, polymers based on vinyl carboxylates. Hydrophobically modified synthetic polymers can be readily prepared by polymerizing monomers with hydrophobic substituents such as hydrophobic alkyl acryl (methacryl) amides, acryl (methacryl) lates, vinyl stearate and supplementary cation or anionic monomers.

Hydrophobically modified, charged dispersants are described in US Pat. Nos. 4,228,277, 4,239,592, 4,687,519; European Patent Applications 189 319, 512 319, 551 817; International patent application WO 94/24169. Dispersants used in the present invention can be prepared in a conventional manner except that they are hydrophobically modified.

The amount of hydrophobically modified dispersant present in the dispersion depends on the type of material and DS _H , the type of sizing agent, DS _A and DS _C , and the required anionic, cationic and solids content of the resulting dispersion. The hydrophobically modified dispersant may be present in the dispersion in an amount of up to 100% by weight, usually 0.1 to 20% by weight, in particular 0.2 to 10% by weight and even 0.3 to 6% by weight, relative to the sizing agent.

In an embodiment of the invention the sizing dispersion comprises a hydrophobically modified dispersant and surfactant as described above. Surfactants are anionic, nonionic or cationic. The surfactant to be used should have an HLB value of 8 to 30, in particular 8-25.

Suitable cationic surfactants include cationic compounds that can function as binders or surfactants between sizing agent particles or droplets and hydrophobically modified cellulose derivatives. Surfactants are preferred of the general formula R ₄ N ⁺ X ^- in comprising an ammonium compound, wherein R is (ⅰ) aliphatic having from hydrogen, (ⅱ) hydrocarbon, in particular 1 to 30 carbon atoms, still more 1 to 22 carbon atoms Alkyl groups, (i) hydrocarbons, in particular aliphatic alkyl groups, having up to 30, in particular 4 to 22, carbon atoms and having at least one heteroatom such as oxygen or nitrogen or a group containing heteroatoms such as carbonyl or acyloxy Wherein at least three, in particular all of the R, comprise at least one carbon atom and at least one, in particular at least two of the R contain at least nine, in particular at least twelve carbon atoms, X ⁻ is an anion, in particular chlorine Halogen ions. Suitable surfactants include dioctyldimethylammonium chloride, didecyldimethylammonium chloride, dicodimethyldimethylammonium, cocobenzyldimethylammonium chloride, coco (fractionated) benzyldimethylammonium chloride, octadecyltrimethylammonium chloride, dioctadecyldimethyl Ammonium chloride, dihexadecyldimethylammonium chloride, di (hydrogenated resin) dimethylammonium chloride, di (hydrogenated resin) benzylmethylammonium chloride, (hydrogenated resin) benzyldimethylammonium chloride, dioleyldimethylammonium chloride and Di (ethylene hexadecanecarboxylate) dimethylammonium chloride. Particularly preferred cationic surfactants include quaternary di- and poly-ammonium compounds comprising at least one hydrocarbon, especially aliphatic alkyl group, having from 9 to 30, in particular from 12 to 22, carbon atoms. Surfactants of this kind include N-octadecyl-N-dimethyl-N'-trimethyl-propylene-diammonium dichlorohydride. Cationic surfactants have a molecular weight of 200 to 800. Suitable anionic surfactants include alkyl, aryl and alkylaryl sulfates and ether sulfates, alkyl, aryl and alkylaryl carboxylates, alkyl, aryl and alkyl aryl sulfonates, alkyl, aryl and alkylaryl phosphates and etherphosphates and dialkyls Sulfosuccinates, alkyl groups having 1 to 18 carbon atoms, aryl groups having 6 to 12 carbon atoms, and alkylaryl groups having 7 to 30 carbon atoms. Suitable anionic surfactants include sodium laurylsulfate, sodium lauryl sulfonate and sodium dodecyl benzenesulfonate.

The surfactant is present in the dispersion in an amount of 0.1 to 20% by weight, in particular 1 to 10% by weight and even 2 to 7% by weight relative to the sizing agent. In a preferred embodiment the sizing dispersion comprises an anionic hydrophobically modified dispersant and a cationic surfactant. Such sizing dispersions are anionic. That is, an anionic dispersant is present in excess. In another embodiment the sizing dispersion comprises a cationic hydrophobically modified dispersant and an anionic surfactant. Such sizing dispersions are cationic. That is, the cation dispersant is present in excess.

The sizing dispersion may be added to the support material in a conventional manner. The term "paper" herein refers to all cellulose based products in the form of sheets and webs, including paper as well as boards and cardboard. The raw materials include cellulose fibers in combination with inorganic fillers and the content of cellulose fibers is usually at least 50% by weight relative to the dry raw material. Conventional inorganic fillers include natural and artificial calcium carbonates such as kaolin, china clay, titanium dioxide, gypsum, talc and chalk, ground marble and precipitated calcium carbonate. The amount of cellulose reactive sizing agent added to the raw material is from 0.01 to 1.0%, in particular from 0.05 to 0.5%, based on the dry weight of the cellulose fiber and the filler, the dosage being the quality of the paper or pulp to be sized, the sizing agent used and the degree of sizing required. Depends on

The present sizing dispersion is used for raw material sizing of cellulose pulp where the raw material has a high cation demand or contains a significant amount of lipophilic material, such as the raw material being made from wood-containing recycled pulp with excessive recycle of white water. The cation demand is at least 50 μeq per liter of feed filtrate, in particular at least 100 μeq and even more than 150 μeq. The cation demand can be measured in a conventional manner, for example by means of a Mutek Particle Charge Detector, using poly (diallyldimethylammonium chloride) as the titrant and feedstock obtained from the raw material filtered through a 1.6 μm filter. The amount of lipophilic material measured by DCM ppm by means of extraction using DCM (dichloromethane) in a known manner is at least 10 ppm, usually at least 20 ppm, in particular at least 30 ppm, even more at least 50 ppm. In addition, the dispersions are subject to excessive recycle of white water, such as when the resulting dry species is used with 0 to 30 tonnes, usually less than 20 tonnes, especially less than 15 tonnes, even less than 10 tonnes, and even less than 5 tonnes of fresh water. Highly white water closure is also favored in the papermaking process. Recycling of the white water in this process is carried out by mixing the white water and cellulose fibers in the form of a solution or suspension before and after the addition of the sizing dispersion to form a stock solution to be dehydrated. Fresh water may be introduced into the process at any stage. For example, it may be mixed with cellulose fibers to form a stock solution, or may be mixed and diluted with a stock solution including cellulose fibers to form a stock solution to be dehydrated before and after mixing the stock solution with white water and before and after adding the sizing dispersion.

Chemicals added to the supporting solution such as preservatives, aluminum compounds, dyes, wet strength resins, brighteners, and the like may also be used with the sizing dispersion of the present invention. Examples of aluminum compounds include alum, aluminate and polyaluminum compounds such as polyaluminum chloride and polysulfate aluminum. Suitable preservatives include silica based sol in combination with cationic polymers, organic polymers, anionic inorganic materials such as bentonite, cationic polymers in combination with cationic polymers or cationic and anionic polymers. Particularly good stock sizing effects are achieved when the dispersion of the invention is used in combination with a preservative including a cationic polymer. Suitable cationic polymers include cationic starch, guar gum, acrylate and acrylamide based polymers, polyethyleneimine, dicyandiamide-formaldehyde, polyamines, polyamidoamines, poly (diallyldimethylammonium chloride) or combinations thereof. Cationic starch and cationic acrylamide based polymers are preferred alone or in combination with each other or with other materials. In an embodiment of the invention, the dispersion is used in combination with a preservation system comprising at least one cationic polymer and anionic silica based particles. The dispersion may be added before, between, after, or simultaneously with the addition of the cationic polymer. The sizing composition may be premixed with a preservation aid such as a cationic polymer such as cationic starch or cationic acrylamide based polymer or anionic silica based material before the obtained mixture is introduced into the paper stock solution.

In a preferred embodiment of the present invention the aqueous dispersion comprises a cellulose reactive sizing agent and an anionic hydrophobically modified cellulose derivative, and also relates to such dispersions and methods for their preparation. This dispersion is especially anionic. Suitable cellulose derivatives include compounds derived from cellulose which are anionic, hydrophobically modified and can function as a dispersant or stabilizer. This cellulose derivative is particularly water soluble or water dispersible. This cellulose derivative comprises one or more hydrophobic groups. Examples of suitable groups include hydrophobic substituents containing 4 to 30 carbon atoms, in particular at least 4, usually at least 6, even more than 8 to 30 carbon atoms and one or more heteroatoms such as oxygen or nitrogen or heteroatoms such as carbonyl or acyloxy Hydrophobic amide, ester and ether substituents, including saturated or unsaturated hydrocarbons with containing groups. Fatty amide-modified cellulose is preferred. This cellulose derivative may have a hydrophobic substitution degree (DS _H ) of 0.01 to 0.8, in particular 0.02 to 0.5, even 0.03 to 0.4. These hydrophobically modified cellulose derivatives are anionic and contain one or more identical or different anionic groups, in particular polyanionic. Suitable anionic groups which are anionic or anionic in water include carboxylic acid, sulfonic acid, phosphoric and phosphonic acids and sulfate groups which may be present as free acids or as water-soluble ammonium or alkaline (generally sodium) salts. Anionic groups can be introduced by chemical denaturation in a known manner. This cellulose derivative may have an anion substitution degree (DS _A ) of 0.1 to 1.4, in particular 0.4 to 0.9, even 0.5 to 0.8. This cellulose derivative comprises carboxyalkyl, in particular carboxymethyl groups.

Examples of cellulose derivatives according to the invention include cellulose derivatives which are hydrophobically modified and supplementally charged, in particular anionic, and which contain carboxymethyl cellulose (CMC), hybrid cellulose ethers of CMC such as hydroxyethyl carboxymethyl cellulose (HECMC), Hydroxypropyl carboxymethyl cellulose (HPCMC), dihydroxypropyl carboxymethyl cellulose (DHPCMC), quaternary nitrogen-containing carboxymethyl cellulose (QNCMC), such as CMC etherified with glycidyl trialkyl ammonium chloride, carboxymethyl ethylsulfo Nate cellulose (CMESC), methyl carboxymethyl cellulose (MCMC). Fatty amide-modified carboxyl containing cellulose is particularly preferred (eg fatty amide modified carboxymethyl cellulose (FACMC)). Methods of introducing suitable hydrophobically modified cellulose derivatives and hydrophobic substituents into anionic cellulose derivatives are disclosed in International Patent Application Publication No. WO 94/24169.

Hydrophobically modified cellulose derivatives may be present in the dispersion in amounts of up to 100% by weight, usually 0.1 to 20% by weight, in particular 0.2 to 10% by weight and even 0.3 to 6% by weight relative to the cellulose reactive sizing agent.

The dispersions according to the invention can be prepared in high solids content and show very good storage stability. The present invention provides improved storage stability or solids high content sizing dispersions. The dispersion may have a sizing agent content of 0.1 to 45% by weight. Dispersions containing ketene dimers according to the invention may have a ketene dimer content of 5 to 45% by weight, in particular 10 to 35% by weight. Dispersions or emulsions containing acid anhydride sizing agents according to the invention may have an acid anhydride content of 0.1 to 30% by weight, in particular 5 to 20% by weight.

Dispersions of the present invention may be produced by mixing the aqueous phase with a dispersant and a sizing agent and supplementally with a surfactant at a temperature at which the sizing agent becomes a liquid and homogenizing the resulting mixture under pressure. The temperature is 55-95 ° C. for ketene dimer sizing agents, and lower temperatures are used for acid anhydrides. The emulsion comprising sizing agent droplets having a diameter of 0.1 to 3 μm is then cooled. In addition to the components mentioned above, dispersants and stabilizers, extenders such as urea and urea derivatives, and preservatives may be incorporated into the sizing dispersion.

It has been found that the components of the present dispersions can be easily homogenized in the presence of an aqueous phase. Therefore, the method for preparing a dispersion comprises (i) mixing a cellulose reactive sizing agent with an anionic cellulose derivative and supplementally a surfactant to obtain an intermediate composition, and (ii) homogenizing the intermediate composition in the presence of an aqueous phase. In particular, the components are mixed homogeneously in step (iii). The sizing agent used in step (iv) can be solid although liquid is preferred to simplify homogeneous mixing. If necessary, after the step, the intermediate can be removed and cooled for solidification to form an anhydrous intermediate sizing composition that allows for simplified shipment in an economical manner. The intermediate sizing composition at the place of use may be homogenized at elevated temperatures such that the intermediate sizing composition becomes liquid in a conventional manner in the presence of water. This method is particularly useful when preparing dispersions of ketene dimers and acid anhydrides, the latter being usually produced in paper mills for direct use as sizing agents in paper production. The storage stable anhydrous sizing composition thus offers economical and technical advantages. The present invention also relates to an anhydrous sizing composition comprising a cellulose reactive sizing agent and an anionic hydrophobically modified cellulose derivative, supplementally with a surfactant, methods of making and uses thereof.

The components present in the compositions of the present invention are cellulose reactive sizing agents, anionic hydrophobic modified cellulose derivatives and surfactants. This composition is virtually anhydrous and small amounts of water may be present. The content of water is from 0 to 10% by weight, in particular less than 5% by weight, even less than 2% by weight. The composition comprises at least 50% by weight, in particular 80 to 99.9% by weight and even 90 to 99.7% by weight of cellulose reactive sizing agent. The cellulose derivative is present in the sizing composition in a defined amount relative to the sizing agent. The anionic cellulose derivative is present in the composition in an amount of up to 100% by weight, usually 0.1 to 20% by weight, in particular 0.2 to 10% by weight and even 0.3 to 6% by weight relative to the sizing agent. In particular the cationic surfactant may be present in the composition in an amount of 0.1 to 20% by weight, in particular 1 to 10% by weight and even 2 to 7% by weight relative to the sizing agent and the total charge of the surfactant and the anionic cellulose derivative is anionic.

The sizing dispersion of the present invention can be used in a conventional manner in the manufacture of paper using cellulose fibers and can be used for surface sizing and internal or stock solution sizing. The present invention also relates to a papermaking process in which an aqueous dispersion is used as a surface or stock solution sizing dispersion. The amount of cellulose reactive sizing agent added to the stock solution containing cellulose fibers and fillers or applied to the paper surface as a surface sizing composition is 0.01 to 1.0% by weight, in particular 0.05 to 0.5% by weight, based on the dry weight of cellulose fibers and fillers. Silver depends on the quality of the pulp or paper to be sized, the cellulose reactive sizing agent used and the degree of sizing required.

The dispersions of the present invention are particularly useful for sizing of cellulose pulp where the stock solution has a high cation demand or contains a significant amount of lipophilic material. The cation requirement, the content of lipophilic extract and the amount of fresh water introduced into the process are described above.

Example 1

Alkyl ketene dimer (AKD) dispersions according to the invention are prepared by mixing an aqueous solution of molten AKD and an anionic hydrophobically modified cellulose derivative at 70 ° C., passing the mixture through a homogenizer and then cooling the dispersion obtained. . The pH of the dispersion is adjusted to about 5 by the addition of acid.

Dispersion 1 was prepared using anionic fatty amide-modified carboxymethyl cellulose (FACMC) containing hydrophobic substituents derived from N-hydrogenated resin-1,3-diaminopropane prepared according to WO 94/24169. Are manufactured. FACMC has a carboxyl substitution of 0.6 and a hydrophobic substitution of 0.1. This dispersion with an average of 1 μm of AKD particles has an AKD content of 30% and contains 1.5% by weight of FACMC relative to AKD.

Dispersion 2 is prepared as above except that cationic surfactant di (hydrogenated resin) dimethylammonium chloride, available under the trade name Querton 442 from Akzo Nobel, is used during homogenization. As can be seen from the negative zeta potential measured by means of the ZetaMaster S version PCS, this dispersion contains AKD particles which are anionic and have an average particle size of 1 μ. AKD content is 30%. Dispersion 2 comprises 3% by weight cationic surfactant and 1% by weight of FACMC relative to AKD.

Example 2

The sizing effect of dispersion 1 according to example 1 is evaluated. Anionic AKD dispersions are prepared and evaluated for comparison using carboxymethyl cellulose (5% by weight CMC to AKD) as dispersant. This standard dispersion 1 was used shortly after preparation because of poor storage stability.

Paper sheets are prepared according to the standard laboratory method SCAN-C23X. Reagents used included 80% of 60:40 bleached birch / pine sulphate and 20% choke added with 0.3 g / L of Na ₂ SO ₄ .10H ₂ O. The stock concentration is 0.5% and pH 8.0. A sizing dispersion was used with the Compozil (trade name) containing an anionic aluminum modified silica sol and cationic starch separately added to the stock solution, and the cationic starch was prepared in an amount of 8 kg / ton for the dry raw material. Is added in an amount of 0.8 kg / ton as calculated by SiO ₂ .

Cobb values measured according to TAPPI standard T 441 OS-63 are shown in Table 2 and the AKD dose is based on the dried stock solution.

Dispersion number AKD Dose (kg / ton) Cobb 60 (g / ㎡) One 0.4 67 One 0.6 28 One 0.8 24 Standard 1 0.4 80 Standard 1 0.6 62 Standard 1 0.8 50

Table 1 shows that the paper sizing effect is improved by using the anionic sizing dispersion according to the present invention.

Example 3

The sizing effect of Dispersion 2 according to Example 1 was evaluated and compared with a conventional anionic AKD dispersion (reference 2) containing a dispersant system consisting of excess lignosulfonate and sodium lignosulfonate and cationic starch do.

The procedure of Example 2 was repeated except that the stock solution contained precipitated calcium carbonate instead of chalk and the cationic starch was 12 kg / ton for the dry stock solution. In some tests, 10 ppm of stearic acid was added to the stock to increase the cation demand and the lipophilic content of the stock to produce a condition similar to that obtained by excessive white water recycling. The results are shown in Table 2.

Dispersion number AKD Dose (kg / ton) Stearic acid (ppm) Cobb 60 (g / ㎡) 2 0.45 - 32 2 0.60 - 28 2 0.75 - 26 2 0.45 10 62 2 0.60 10 36 2 0.75 10 27 Standard 2 0.45 - 50 Standard 2 0.60 - 32 Standard 2 0.75 - 30 Standard 2 0.45 10 103 Standard 2 0.60 10 76 Standard 2 0.75 10 35

As can be seen from Table 2, the dispersion 2 of the present invention has a better sizing effect than the comparative anionic dispersion (reference 2) and especially improved sizing effect when the stock solution contains higher cation demand and a significant amount of lipophilic material. Obtained.

Claims (22)

As an aqueous sizing dispersion containing a cellulose reactive sizing agent and a hydrophobically modified dispersant to add a sizing dispersion to a stock solution containing cellulose fibers and a filler to size the cellulose fibers and dehydrate the stock onto a wire to obtain a web containing cellulose fibers. An aqueous sizing dispersion characterized in that the stock solution has a cation requirement of at least 50 μeq per liter of stock filtrate. The dispersion according to claim 1, wherein the stock solution has a lipophilic substance content of 10 ppm or more. The dispersion according to claim 1 or 2, wherein the stock solution has a cation demand of at least 100 µeq per liter of the stock filtrate. The dispersion according to claim 1, 2 or 3, wherein the stock solution has a lipophilic content of 50 ppm or more. The dried cellulose product 1 according to claim 1, 2, 3 or 4, wherein the dehydration process is recycled to form a cellulose fiber-containing stock solution to be dehydrated and generates white water into which new water is introduced, and the amount of water introduced is generated. Dispersion, characterized in that less than 30 tons per ton. 6. The dispersion of claim 5 wherein the amount of water introduced is less than 10 tonnes per tonne of dry cellulose product produced. The dispersion as claimed in claim 1, wherein the hydrophobically modified dispersant is anionic or amphoteric. The dispersion of claim 1, wherein the hydrophobically modified dispersant is based on polysaccharide. The dispersion as claimed in claim 1, wherein the hydrophobically modified dispersant is an anionic hydrophobically modified cellulose derivative. 10. Dispersion according to claim 1, 7, 8, or 9, characterized in that the hydrophobically modified dispersant comprises accessory hydrophobic groups containing 6 to 30 carbon atoms. The dispersion according to any one of the preceding claims, wherein the sizing agent is a ketene dimer or an acid anhydride. A sizing agent aqueous dispersion comprising a cellulose reactive sizing agent and an anionic hydrophobic modified cellulose derivative. 13. Dispersion according to claim 12, wherein the cellulose derivative comprises 4 to 30 carbon atom containing hydrophobic groups. 14. A cellulose derivative according to claim 12 or 13 comprising hydrophobic amide, ester or ether substituents containing saturated or unsaturated hydrocarbon chains containing at least 8 carbon atoms and having at least one heteroatom or heteroatom containing group inserted therein. Dispersion made. The dispersion according to claim 12, 13 or 14, wherein the cellulose derivative is fatty amide-modified carboxymethyl cellulose. The dispersion according to claim 12, 13, 14 or 15, wherein the sizing agent is a ketene dimer or an acid anhydride. 17. The dispersion according to any one of claims 12 to 16, wherein the dispersion is anionic. A cellulose fiber stock solution sizing method comprising the step of adding a dispersion according to any one of claims 12 to 17 to a support solution containing cellulose fibers. A method for preparing a dispersion according to any one of claims 12 to 17, comprising homogenizing the cellulose reactive sizing agent in the presence of an aqueous phase and an anionic hydrophobically modified cellulose derivative. 20. The method of claim 19 comprising providing an anhydrous composition containing a cellulose reactive sizing agent and an anionic hydrophobically modified cellulose derivative and homogenizing the anhydrous composition in the presence of the aqueous phase. Anhydrous composition comprising a cellulose reactive sizing agent and an anionic hydrophobic modified cellulose derivative. 22. The composition of claim 21 wherein the cellulose reactive sizing agent is a ketene dimer and the anionic hydrophobically modified cellulose derivative is based on carboxymethylcellulose.