EP0819193A1

EP0819193A1 - Paper sizing agent mixtures

Info

Publication number: EP0819193A1
Application number: EP96908139A
Authority: EP
Inventors: Roland Ettl; Primoz Lorencak; Wolfgang Reuther; Johann Bonn; Arnold De Clercq
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1995-04-03
Filing date: 1996-03-26
Publication date: 1998-01-21
Anticipated expiration: 2016-03-26
Also published as: EP0819193B1; DE19512399A1; DK0819193T3; JPH11502575A; ATE180526T1; ES2133193T3; JP3805367B2; DE59602009D1; WO1996031650A1

Abstract

Paper sizing agent mixtures of: (A) finely divided aqueous dispersions of C14 to C22 alkyl diketenes obtainable by dispersing the alkyl diketenes in water in the presence of cationic starch with an amylopectin content of at least 95 wt.%, and (B) finely divided aqueous polymer dispersions forming a paper sizing agent, process for producing the paper sizing agent mixtures by mixing th e components (A) and (B) and the use of the paper sizing agent mixtures as mass and surface sizing agents for paper, pasteboard and cardboard.

Description

Paper sizing mixtures

description

The invention relates to paper sizing mixtures

(A) finely divided, aqueous dispersions of C 1 -C 22 -alkyldiketenes which can be obtained by dispersing the alkyldiketenes in water in the presence of cationic starch and

(B) polymer dispersions that are a sizing agent for paper,

Process for the preparation of the above-mentioned paper line mixtures by mixing components (A) and (B) or by emulsifying C ₁ -C 2 -alkyldiketenes in a mixture of aqueous suspensions of cationic starches and finely divided, aqueous polymer dispersions which are a sizing agent for paper at temperatures of at least 70 ° C and using the paper sizing mixtures as mass and surface sizing agents for paper, cardboard and cardboard.

The above-mentioned paper sizing mixtures as well as their production and use are known from WO-A 94/05855.

The aqueous dispersions specified under (A) and (B) belong to the prior art. For example, US Pat. No. 3,130,118 discloses aqueous alkyldiketene dispersions which can be obtained by dispersing the alkyldiketenes in water in the presence of cationic starch. Fatty alkyl diketene

Dispersions which are prepared in the presence of cationic condensates and optionally cationic starch are known, for example, from DE-A-30 00 502 and DE-A-33 16 179. Stabilized aqueous alkyldiketene dispersions are known from EP-B-0 437 764 which can contain up to 40% by weight of alkyldiketene in dispersed form and which, as stabilizer, contain long-chain fatty acid esters and / or urethanes in addition to cationic starch.

Aqueous polymer dispersions which are a sizing agent for paper are described, for example, in the following references: JP-A-58/115 196, EP-B-0 257 412, EP-B-0 267 770, EP-B-0 051 144, EP-A-0 058 313 and EP-A-0 150 003. These references are referenced in the aforementioned WO-A-94/05855. From DE-A-3 235 529 paper sizing mixtures are known which consist of emulsions of C ₄ to C ₂ o-alkyldiketenes and finely divided polymer dispersions containing copolymerized nitrogen-containing monomers and which consist of the abovementioned EP-B-0 051 144 are known. These sizing mixtures are prepared by combining a fatty alkyl diketene emulsion with an aqueous, finely divided polymer dispersion or are formed in the paper stock before sheet formation by adding the emulsified fatty alkyl diketene and the finely divided aqueous dispersion to the paper stock at the same time and mixing the system well. Mixtures which can only be obtained by stirring in cationic, finely divided aqueous polymer dispersions in fatty alkyl diketene dispersions are not sufficiently stable in storage.

EP-B-0 353 212 discloses sizing agents in the form of aqueous emulsions which contain a hydrophobic cellulose-reactive sizing agent, e.g. Fatty alkyl diketene and a cationic starch with an amylopectin content of at least 85% and a degree of cationization (D.S.) from 0.045 to 0.40. The proportion of amylopectin in the cationic starch is preferably 98 to 100%. Starch which is preferably used is waxy corn starch.

From EP-B-0 369 328 aqueous alkyldiketene dispersions are known which contain up to 30% by weight of ketene dimer. Other essential components of these alkyldiketene dispersions are cationic starch, preferably cationic waxy maize starches, aluminum sulfate, carboxylic acids with 1 to 10 carbon atoms, and sulfonates, such as lignosulfonic acid or condensation products of formaldehyde and naphthalenesulfonic acids.

The object of the present invention is to provide an improved paper sizing agent containing fatty alkyl diketenes which, when used as a mass sizing agent, results in adequate instant sizing and does not impair the whiteness of the paper or in comparison the known mixtures has improved shear and storage stability.

The object is achieved according to the invention with paper size mixtures

(A) finely divided, aqueous dispersions of C 1 -C ₂₂ -alkyldiketenes which can be obtained by dispersing the alkyldiketenes in water in the presence of cationic starch and (B) finely divided, aqueous polymer dispersions which are a sizing agent for paper,

if the amylopectin content of the cationic starch of component (A) is at least 95%. The amylopectin content of the cationic starch is preferably 98 to 100%. Suitable starches of this type are preferably cationic waxy maize starches.

The invention also relates to a process for producing paper size mixtures by mixing

(A) finely divided, aqueous dispersions of -C ₄ to C.22-alkyldiketenes which can be obtained by dispersing the alkyldiketenes in water in the presence of cationic starch

(B) finely divided, aqueous polymer dispersions which are a sizing agent for paper,

or by emulsifying C 1 to C 22 alkyldiketenes in a mixture of aqueous suspensions of cationic starches of finely divided, aqueous polymer dispersions, which are a sizing agent for paper, at temperatures of at least 70 ° C. The process is characterized in that the amylopectin content of the cationic starches is at least 95%.

The invention also relates to the use of the paper sizing mixtures described above as mass and surface sizing agents for paper, cardboard and cardboard.

For the preparation of component (A) one starts from C 1 -C ₂₂ -alkyldiketenes or from mixtures of such alkyldiketenes. Alkyldiketenes are known and commercially available. They are produced, for example, from the corresponding carboxylic acid chlorides by splitting off hydrogen chloride with tertiary amines. Suitable fatty alkyldiketenes are, for example, tetradecyldiketene, hexadecyldiketene, octadecyldiketene, alkosyldiketene, docosyldiketene, palmityldiketene, stearyldiketene and behenyldiketene. Also suitable are diketenes with different alkyl groups, for example stearylpalmithyldiketene, behenylstearyldiketene, behenyl oleyldiketene or palmithylbehenyldiketene. Stearyldiketene, palmithtyldiketene, behenyldiketene or mixtures of stearyldiketene and palmithyldiketene or mixtures of behenyldiketene and stearyldiketene are preferably used. The diketenes are present in the aqueous emulsions in concentrations of 5 to 60, preferably 10 to 40,% by weight. The alkyldiketenes are emulsified in water in the presence of cationic starch, which according to the invention has an amylopectin content of at least 95, preferably 98 to 100%. Such starches can be obtained, for example, by fractionation of conventional native starches or by breeding measures from plants which produce practically pure amylopectin starch, cf. Günther Tegge, Starch and Starch Derivatives, Hamburg, Bers-Verlag 1984, pages 157 to 160. Cationic starches with an amylopectin content of at least 95, preferably 98 to 100% by weight are available on the market. The amylopectin starches have a branched structure and have a high degree of polymerization. The molecular weights (number average) are, for example, 200 million to 400 million. For waxy maize starch with an amylopectin content of 99 to 100%, average molar masses (number average) of approx

Stated 320 million. According to the invention, cationized starches are used whose amylopectin content is at least 95%. The degree of cationization of the starch is indicated with the aid of the degree of substitution (D.S.). This value reflects the number of cationic groups per monosaccharide unit in the cationic starch. The degree of substitution (D.S. value) of the cationic starches is, for example, 0.010 to 0.150. In most cases it is below 0.045, e.g. the cationic starches in question preferably have a degree of substitution (D.S.) of 0.020 to 0.040.

The starch containing at least 95% by weight of amylopectin is cationized by introducing groups which contain tertiary or quaternary nitrogen atoms, e.g. by reacting the starches in question, in particular waxy corn starch, with dialkylaminoalkyl epoxides of the formula

or with dialkylaminoalkyl chlorides of the formula

or preferably with quaternary ammonium salts of the formula containing epoxide groups R2

"Θ

CH ₂ CH R ¹ N - ^• R3 (III)

^ 0 ^ |

R ⁴

or the corresponding halohydrins of the formula

R2

C1CH ₂ CH ₂ CH Rl NR ³ X® (IV)

OH R ⁴

In the formulas I to IV, the substituents R ² , R ³ and R ^{4 are} alkyl, aryl, aralkyl or hydrogen, R ¹ is an alkylene group, for example Ci-C _ß- alkylene. Examples of such compounds are 3-chloro-2-hydroxypropyltrimethylammonium chloride or glycidyltrimethylammonium chloride.

In addition to the preferred waxy maize starch, wax potato starch, waxy wheat starch or mixtures of the starches mentioned are each suitable in cationized form.

The cationic starches with amylopectin contents of at least 95% are contained in the aqueous alkyldiketene dispersion in an amount of 0.5 to 5, preferably 1 to 3,% by weight; the finely divided, aqueous dispersions of component (A) are usually so prepared that the starches containing at least 95% amylopectin are first converted into a water-soluble form. This can be done, for example, with the aid of oxidative or hydrolytic degradation in the presence of acids or simply by heating the cationic starches. The starch is preferably digested in a jet cooker at temperatures in the range from 100 to 150.degree. At least one C 1 -C ₂₂ -alkyldiketene is then dispersed in the aqueous solution of the cationic starch with a minimum amylopectin content of at least 95% by weight at temperatures above 70 ° C., for example in the range from 70 to 85 ° C. The alkyldiketene dispersion is then cooled so that the alkyldiketenes are in solid form. Finely divided aqueous alkyldiketene dispersions having an average particle diameter of, for example, 0.5 to 2.5, preferably 0.8 to 1.5, are obtained. The dispersion of the alkyldiketenes in water can optionally additionally in the presence of lignosulfonic acid, condensates of formaldehyde and naphthalene sulfonic acids, polymers containing styrene sulfonic acid groups or the alkali metal and / or ammonium salts of the compounds containing said sulfonic acid groups. These substances act as dispersants and stabilize the resulting alkyl diketene dispersions. If these dispersants are used in the production of the alkyldiketene dispersions, the amounts used are, for example, 0.01 to 1, preferably 0.02 to 0.2% by weight, based on the alkyldiketene dispersion.

In the preparation of the alkyldiketene emulsions it is possible to use, in addition to the cationic wax starches, other customary protective colloids which have hitherto been used in the preparation of alkyldiketene emulsions, e.g. Water-soluble cellulose ethers, polyacrylamides, polyvinyl alcohols, polyvinyl pyrrolidones, polyamides, polyamidoamines and mixtures of the compounds mentioned. Component (A) may optionally contain further substances which are common in alkyldiketene dispersions, e.g. Ci to Cio carboxylic acids, e.g. Formic acid, acetic acid or propionic acid. If they are contained in the alkyldike¬ ten dispersions, the acids are used in amounts of 0.01 to 1% by weight. The alkyldiketene dispersions can optionally also contain conventional biocides, which can be used in amounts of up to 1% by weight.

Component (B) of the paper sizing mixtures according to the invention consists of finely divided, aqueous polymer dispersions which are a sizing agent for paper. Such polymer dispersions are known, for example, from EP-B-0 051 144, EP-B-0 257 412, EP-B-0 276 770, EP-B-0 058 313 and EP-B-0 150 003 . Such polymer dispersions which act as paper sizing agents are obtainable, for example, by mixing 1 to 32 parts by weight of a mixture

(a) styrene, acrylonitrile and / or methacrylonitrile,

(b) Acrylic acid and / or methacrylic acid esters of Ci to Ciβ alcohols and / or vinyl esters of saturated C2 to C carboxylic acids and optionally

(c) other monoethylenically unsaturated copolymerizable monomers

in aqueous solution in the presence of 1 part by weight of a solution copolymer (1) di-Ci to C ₄ -alkylamino-C2 to C-alkyl (meth) acrylates, which may optionally be protonated or quaternized,

(2) nonionic, hydrophobic, ethylenically unsaturated monomers, in the case of these monomers, if they are polymerized on their own, form hydrophobic polymers and, if appropriate

(3) monoethylenically unsaturated C to Cs carboxylic acids or their anhydrides, the molar ratio of (1): (2): (3) =

Is 1: 2.5 to 10: 0 to 1.5, copolymerized.

A solution copolymer is first prepared in which the monomers of groups (1) and (2) and optionally (3) are copolymerized in a water-miscible organic solvent. Suitable solvents are, for example, C ₁ -C ₃ -carboxylic acids, such as formic acid, acetic acid and propionic acid, or C 1 -C ₄ -alcohols, such as methanol, ethanol, n-propanol or isopropanol, and ketones such as acetone. The group (1) monomers used are preferably dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylate and dimethylaminopropylacrylate. The monomers in group (1) are preferably used in protonated or quaternized form. Suitable quaternizing agents are, for example, methyl chloride, dimethyl sulfate or benzyl chloride.

The group (2) monomers used are nonionic, hydrophobic, ethylenically unsaturated compounds which, when polymerized on their own, form hydrophobic polymers. These include, for example, styrene, methylstyrene, Ci bis

Ciβ-alkyl esters of acrylic acid or methacrylic acid, for example methyl acrylate, ethyl acrylate, N-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate and isobutyl acrylate as well as isobutyl methacrylate, n-butyl methacrylate and tert-butyl methacrylate. Acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate and vinyl butyrate are also suitable. Mixtures of the group 2 monomers can also be used in the copolymerization, for example mixtures of styrene and isobutyl acrylate. The solution copolymers used as emulsifiers can optionally also contain copolymerized monomers of group (3), for example monoethylenically unsaturated C ₃ - to Cs-carboxylic acids or their anhydrides, for example acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic acid anhydride or itaconic anhydride. The molar ratio of (1): (2): (.3) is 1: 2.5 to 10: 0 to 1.5. The copolymer solutions obtained in this way are diluted with water and in this form serve as a protective colloid for the polymerization of the above-mentioned monomer mixtures of components (a) and (b) and optionally (c). Suitable monomers of group (a) are styrene, acrylonitrile, methacrylonitrile or mixtures of styrene and acrylonitrile or of styrene and methacrylonitrile. The group (b) monomers used are acrylic acid and / or methacrylic acid esters of C 1 -C 4 -alcohols and / or vinyl esters of saturated C 2 -C 4 -carboxylic acids. This group of monomers corresponds to the monomers of group (2), which has already been described above. Preferably used as the monomer of group (b) are butyl acrylate and butyl methacrylate, for example isobutyl acrylate, n-butyl acrylate and isobutyl methacrylate. Monomers of group (c) are, for example, C ₃ - to C 5 -monoethylenically unsaturated carboxylic acids, acrylamidomethylpropanesulfonic acid, sodium vinyl sulfonate, vinyl imidazole, N-vinyl formamide, acrylamide, methacrylamide and N-vinyl imidazoline. 1 to 32 parts by weight of a monomer mixture of components (a) to (c) are used per 1 part by weight of the copolymer. The monomers of components (a) and (b) can be copolymerized in any ratio, for example in the molar ratio 0.1: 1 to 1: 0.1.

If necessary, the monomers of group (c) are used to modify the properties of the copolymers.

The finely divided, aqueous dispersions described as sizing agents for paper, which are known from EP-0 257 412 and EP-B-0 276 770, are preferably used. These dispersions are obtained by copolymerizing

(a) 20 to 65% by weight of styrene, acrylonitrile and / or methacrylonitrile,

(b) from 80 to 35 wt .-% acrylic and / or methacrylic acid esters of monohydric saturated C ₃ - to Ce-alcohols and

(c) 0 to 10% by weight of other monoethylenically unsaturated copolymerizable monomers

prepared in the presence of free radical initiators in the manner of an emulsion polymerization in an aqueous solution of a degraded starch as a protective colloid. The degraded starch preferably has viscosities ηi = 0.04 to 0.50 dl / g. These starches have been subjected to oxidative, thermal, acidolytic or enzymatic degradation. All native starches can be used for this degradation, for example starches from potatoes, wheat, rice, tapioca and corn, and starches with amylopectin contents of at least 95, preferably 98 to 100% by weight, for example waxy corn starch, waxy potato starch, wax white Zen starch or mixtures of the starches mentioned. In addition, chemically modified starches can be used, such as starches containing hydroxyethyl, hydroxypropyl or quaternized aminoalkyl groups with viscosities in the range given above. Oxidatively degraded potato starches, cationized, degraded potato starches or hydroxyethyl starch are particularly suitable. The mixture of size-acting copolymer dispersion and an undigested starch is preferably stirred at 85 ° C. for at least 10 minutes. This unlocks the strength.

10

The degraded starches act as emulsifiers in the copolymerization of the monomers (a) to (c) in an aqueous medium in the manner of an emulsion polymerization. The monomers are copolymerized in an aqueous solution containing 1 to 21, preferably 3 to

15 contains 15% by weight of broken down starch. 10 to 140, preferably 40 to 100 parts by weight of the monomer mixture of (a) and (b) and optionally (c) are polymerized in 100 parts by weight of such a solution. The diameter of the dispersed polymer particles is 50 to 350, preferably 100 to 250 nm. As the monomer of

20 group (b) are also vinyl esters of C ₂ - to C ₄ -saturated carboxylic acids. Suitable monomers of group (c) are, for example, acrylamide, methacrylamide, stearyl acrylate, stearyl methacrylate, palmityl acrylate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid,

25 vinylsulfonic acid, acrylamidopropanesulfonic acid and acrylic acid and methacrylic acid esters of amino alcohols, e.g. Dimethylaminoethyl¬ acrylate, dimethylaminoethyl methacrylate, dimethylaminopropylacrylate and dimethylaminomethacrylate.

30 The paper sizing mixtures according to the invention are produced by known processes, cf. DE-A-32 35 529 and W0-A-94/05855. The procedure is, for example, that (A) finely divided, aqueous dispersions of C ₁₄ -C ₂₂ -alkyldiketenes which are dispersed in water by dispersing the alkyldiketenes

35 Presence of cationic starch with an amylopectin content of at least 95% are available, with (B) finely divided, aqueous polymer dispersions which are a sizing agent for paper, mixes with each other or Cχ ₄ - to C ₂₂ ~ alkyldiketenes in a mixture of aqueous solutions of cationic starches with an amylo-

40 pectin content of at least 95%, the starches having been converted into a water-soluble form and emulsifying finely divided, aqueous polymer dispersions which are a sizing agent for paper at temperatures of at least 70 ° C. The emulsification is preferably carried out here under the action of high shear forces, e.g. in so-

45 named homogenizers. The resulting emulsions are preferably rapidly cooled to room temperature. The resulting dispersions of paper size mixtures have one pH in the range from 2 to 4, preferably the pH is 3. The paper sizing mixtures can also be prepared by mixing components (A) and (B), for example in a stirred kettle, and adding this mixture - 5 if homogenized under the action of high shear forces at temperatures of, for example, 20 to 70 ° C. The paper sizing mixtures according to the invention contain, for example, 1 to 55, preferably 10 to 30% by weight of alkyldiketenes and 1 to 60, preferably 3 to 25% by weight of finely divided polymer dispersions, 10 in each case based on the solids.

For the production of the paper sizing mixtures according to the invention, 0.1 to 1.2, preferably 0.3 to 0.9, by weight, for example, is used per 1 part by weight (diketene) of component (A).

15 parts of polymer dispersion of component (B), based on the solids. For example, a single finely divided aqueous polymer dispersion or a mixture of 2 or more polymer dispersions, each of which is a sizing agent for paper, can be used. The particle diameter of the finely divided aqueous

20 polymer dispersions is, for example, 50 to 400, preferably 100 to 250 nm. The sizing agent mixtures according to the invention are stable on storage, i.e. they do not tend to separate and do not become solid. They also have a very low viscosity (for example after storage of

25 90 days at room temperature, the viscosities are below 100 mPas, measured in a Brookfield viscometer at 100 rpm, and a temperature of 25 ° C with spindle No. 1) and are also characterized by a high stability against the action of Shear forces, such as those used for pumping

30 pen occur. The sizing mixtures are used as mass and surface sizing agents for paper, cardboard and cardboard. Use as a mass sizing agent in the manufacture of paper is preferred.

35 The percentages in the examples mean% by weight, the parts are parts by weight.

40

45 Examples

Polymer dispersion 1

34.0 g of starch A and 8.4 g of starch B are suspended in 148 g of water in a 1 1 four-necked flask which is equipped with a stirrer, reflux condenser, metering device and a device for working under a nitrogen atmosphere and is stirred with stirring Heated to 85 ° C.

10

Starch A is a degraded cationic potato starch with a viscosity ηi of 0.47 dl / g, a degree of substitution of 0.015-COOH and 0.027 N mol / mol glucose units and a solids content of 83%.

15

Starch B is a degraded, cationic potato starch with a viscosity ηι of 1.16, a degree of substitution of 0.07 N mol / mol of glucose units and a solids content of 83%.

20 After 30 minutes at 85 ° C., 2.6 g of an aqueous 10% calcium acetate solution and 10 g of a 1% enzyme solution (α-amylase A) are added. After a further 20 minutes at 85 ° C, the enzymatic starch degradation is stopped by adding 1.5 g of glacial acetic acid. Then 16.5 g of a 1% iron (II) sulfate solution and 1.75 g

25 30% hydrogen peroxide added. After 20 minutes, the hydrogen peroxide has decomposed and the oxidative starch degradation has ended. The intrinsic viscosity of the starch mixture is then 0.08 dl / g. Then 1.8 g of 30% hydrogen peroxide are added and an emulsion consisting of 93.7 g of acrylonitrile,

30 76.4 g of n-butyl acrylate and a solution of 0.2 g of Na ₄ -C ₄ -alkyl sulfonate in 50 g of water consistently, within 1 hour and at the same time separately 50 g of a 3.12% hydrogen peroxide solution inflict within 1.75 hours. During this time and 60 minutes after the end of the monomer dose

The temperature of the reaction mixture is kept at 85 ° C. A dispersion with a solids content of 41.0% and a particle diameter (without starch shell) of 100-150 nm is obtained. The dispersion is diluted to a solids content of 33% by adding water.

40

Polymer dispersion 2

A mixture of 20 parts (1.92 mol) of styrene, 7 parts (0.41 mol) of dimethylaminopropylmethacryla id. 3.5 parts of 45 (0.486 mol) of acrylic acid and 10 parts of acetic acid were pumped into a kettle heated to 90 ° C. within 1 hour using a pump. Simultaneously and also within 1 hour 2 parts of azoisobutyronitrile and 10 parts of acetic acid were added using another metering device. The mixture was heated to a temperature of 90 ° C. for 30 minutes and then dissolved in 180 parts of water. Then 0.01 part of iron sulfate was added and a mixture of 32 parts of styrene and 32 parts of isobutyl acrylate was polymerized therein at a temperature of 85 ° C. Separately, 33 parts of a 6% hydrogen peroxide solution were added continuously to the prepolymer over the course of 2 hours. After post-polymerization for 1 hour at a temperature of 85 ° C., a finely divided dispersion with a solids content of 31.4% and a particle diameter of 150-250 nm resulted. The dispersion is diluted to a solids content of 20% by adding water.

example 1

A 2.80% aqueous solution of a commercially available cationic waxy maize starch (D.S. 0.03, amylopectin content is prepared

> 98%) by suspending the required amount of starch in water and stirring the suspension for 15 minutes at a temperature of 95 ° C. 15 parts of polymer dispersion 1 are added to 85 parts of the starch solution thus obtainable at a temperature of 85 ° C. The mixture is stirred for 10 minutes.

To 84 parts of the mixture of waxy maize starch and polymer dispersion 1 described above, 16 parts of a C 1 _& / Ci ₈ -alkyldiketen melt are added and the mixture is briefly treated with an ultraturax. This mixture is then homogenized twice at 150 bar in an intensive mixer. The emulsion is then rapidly cooled to room temperature. The properties of the sizing agent dispersion are given in Table 1.

Example 2

A 3.66% aqueous solution of a commercially available cationic waxy maize starch (D.S. 0.03, amylopectin content)

> 98%) by suspending the required amount of starch in water and digesting the suspension in a jet cooker at a temperature of 125 ° C. 35 parts of polymer dispersion 2 are added to 65 parts of the starch solution thus obtainable at a temperature of 85 ° C. The mixture is then stirred for 10 minutes.

84 parts of the mixture described above from the aqueous solution of the digested cationic starch and the polymer dispersion 2 are added to 16 parts of a Ci ₆ / Ci8 alkyldiketene melt and the mixture is briefly treated with an Ultraturrax. This The mixture is then treated twice in a homogenizer at 150 bar and then rapidly cooled to room temperature. The properties of the paper size mixture are given in Table 1. 5

Example 3

A 4.17% aqueous solution of a commercially available cationic waxy maize starch (D.S. 0.04, amylopectin content is prepared

10> 98%) in which the starch is first suspended in water and digested in a jet cooker at a temperature of 125 ° C. Then 0.1 part of the sodium salt of a lignin sulfonic acid and then 20 parts of a Ci ₆ / Ci ₈ alkyl diketene melt are added to the starch solution and the mixture is treated

15 with an Ultraturrax. The initially coarse suspension is passed through a homogenizer twice at a temperature of 85 ° C. and a pressure of 150 bar and then rapidly cooled to room temperature.

20 90 parts of the alkyldiketene dispersion described above are then mixed with 10 parts of polymer dispersion 1 with stirring and treated twice in a homogenizer under a pressure of 150 bar. The properties of the paper mixture composition are given in Table 1.

25

Example 4

A commercial cationic waxy maize starch (D.S. 0.04, amylopectin content 100%) is soaked in water in such an amount.

30 worn that a 4.17% aqueous suspension is formed. This suspension is then digested in a jet cooker at a temperature of 125 ° C., so that an aqueous starch solution is obtained, to which 0.15 part of the sodium salt of a lignosulfonic acid and then 25 parts of a Cie / Ciβ-alkyldiketene melt are added. The

The mixture is first treated with an Ultraturrax and then twice in a homogenizer under a pressure of 150 bar and a temperature of 85 ° C. and then rapidly cooled to room temperature.

40 30 parts of polymer dispersion 2 are added to 70 parts of the alkyldiketene emulsion described above and the resulting mixture is homogenized twice in a homogenizer at a pressure of 150 bar. The properties of the paper sizing mixture obtainable in this way are given in Table 1.

45 Comparative Example 1

A 5.13% strength aqueous suspension of a commercially available cationic starch (D.S. 0.02, amylopectin content 70%) is first prepared, and 50 parts of the suspension were added to 50 parts of this suspension

Polymer dispersion 1 and the starch by heating for 10 minutes in the mixture with the polymer dispersion 1 at a temperature of 85 ° C.

A melt of 20 parts of stearyldiketene and 2 parts of stearic acid ethyl ester, heated to 90 ° C., was added to 78 parts of the mixture of the digested starch and polymer dispersion 1, and the mixture was then homogenized as described in Example 1. A stable, 20% strength aqueous stearyl diketene emulsion was obtained which, in addition to stearyl diketene, contained 2% starch, 2% stearic acid oleate ester as stabilizer and 12.9% of polymer dispersion 1. The properties of the dispersion are given in Table 1.

Comparative Example 2

Example 1 was repeated with the changes that a 5.13% strength aqueous suspension of a commercially available cationic starch (degree of substitution 0.02, amylopectin content 75%) was prepared, mixed with 50 parts of polymer dispersion 2 and the

Digestion by heating the mixture to 85 ° C for a total of 10 minutes. A melt of 20 parts of stearyldiketene and 2 parts of stearic acid ethyl ester, heated to 90 ° C., was then added to 78 parts of the mixture of digested starch and polymer dispersion 2 thus obtained, and the melt therein was emulsified as described in Example 1. The properties of the sizing agent mixture are given in Table 1.

Table 1

Bei¬ viscosity average viscosity Final stability play after Her¬ after particle sizing in storage position 3 months size (Cobb) (3 months) distribution

[mPas] [mPas] [μm]

1 14.0 16.1 1.21 25 stable

2 22.8 32.8 1.65 27 stable

3 13.9 45.3 2.05 30 stable

4 30.8 43.7 2.62 30 stable

See 39.2 135 2.20 27 phase example

See 27.1 236 2.45 27 phase example 2 separation

The shear stability of the sizing agent mixtures described in the examples and comparative examples was determined by pumping the mixtures through a 400 μm filter using a centrifugal pump. 500 ml of the paper size mixture was used in each case and the temperature of the mixture was kept at 25 ° C. during the test. Table 2 shows the times after which the filter became blocked or the test was terminated.

Table 2: Shear stability test (pump test)

Sizing agent termination after remarks mixed according to [min] example

1 60 filters free

2 55 filter clogged

3 60 filters free

4 44 Filter clogged

See example 1 15 filter clogged

See example 2 23 Filter clogged

Claims

Patent claims

1. Paper sizing mixtures

(A) finely divided, aqueous dispersions of C ₄ to C 22 alkyldiketenes, which can be obtained by dispersing the alkyldiketenes in water in the presence of cationic starch, and

(B) finely divided, aqueous polymer dispersions which are a size for paper,

characterized in that the amylopectin content of the cationic starch of component (A) is at least 95%.

2. paper sizing mixtures according to claim 1, characterized ge indicates that the amylopectin content of the cationic starch is 98 to 100%.

3. paper size mixtures according to claim 1, characterized ge indicates that the cationic starch is a cationic waxy corn starch.

4. Paper sizing mixtures according to one of claims 1 to 3, characterized in that in the preparation of component (A) the dispersion of the alkyldiketenes in water additionally in the presence of lignosulfonic acid, condensates of formaldehyde and naphthalenesulfonic acids, and styrene sulfonic acid-containing polymers or the compounds containing the alkali metal and / or ammonium salts of the sulfonic acid groups mentioned.

5. Process for the preparation of paper sizing mixtures by mixing

(A) finely divided, aqueous dispersions of Cχ ₄ - to C22-alkyldiketenes, which can be obtained by dispersing the alkyldiketenes in water in the presence of cationic starch

or by emulsifying C ₄ to C 22 alkyl diketenes in a mixture of aqueous suspensions of cationic starches and finely divided, aqueous polymer dispersions which contain a Means for paper are, at temperatures of at least 70 ° C, characterized in that the amylopectin content of the cationic starches is at least 95%.

5 6. The method according to claim 5, characterized in that the amylopectin content of the cationic starches is 98 to 100%.

7. The method according to claim 5 or 6, characterized in that 10 one uses cationic wax corn starches as starches.

8. The method according to any one of claims 5 to 7, characterized gekenn¬ characterized in that the degree of substitution (D.S.) of the cationic starches is 0.010 to 0.150.

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9. The method according to claim 8, characterized in that the degree of substitution (D.S.) of the cationic starches is below 0.045.

20 10. The method according to claim 8, characterized in that the degree of substitution (D.S.) of the cationic starches is 0.020 to 0.040.

11. Use of the paper sizing mixtures according to claims 25 to 4 as mass and surface sizing agents for paper, cardboard and cardboard.

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