DD159078A1 - PROCESS FOR PREPARING ALKALIFESTER PAPER GLUE SOLUTIONS - Google Patents

Abstract

The invention relates to a method for producing alkali-free sizing agents based on alpha-methylstyrene-maleic anhydride copolymers, which are useful as sizing agents in the acidic, neutral and weakly alkaline range for papers and boxes of various kinds and quality. According to the invention, alpha-methylstyrene-maleic anhydride copolymers with relative molecular weights of between 800 and 20,000 are first reacted with alcohols with half ester formation and then further esterified with epoxide compounds in the presence of tertiary amines. The result is alcoholic polymer solutions having solids contents between 30 and 70%, from which after reaction with aqueous ammonia 15 to 25% aqueous-alcoholic Papierleimloesungen are obtained.

Description

VEB Leuna-Werke Leuna, 10.4.81

"Walter Ulbricht"

LP 8109

Title of the invention

Process for the preparation of alkali-resistant paper glue solutions Field of application of the invention

The invention relates to a method for producing alkali-resistant sizing agents for paper and cardboard based on 06-methylstyrene-maleic anhydride copolymers.

Characteristic of the known technical solutions

The use of alternately constructed copolymers of maleic anhydride and vinylaromatics, such as styrene, p-vinyltoluene and CX-methylstyrene, after chemical reaction with ammonia, aliphatic or aromatic amines or with C. to C 1-4 -alcohols for surface sizing of paper or cardboard is known". According to DE-OS 1811579, otyrene-maleic half-ester copolymers in the form of the ammonium salts in combination with starch are known as sizing agents for paper. The use of CX-methylstyrene-maleic anhydride copolymers as surface size is described in DD-PS 142217. Thereafter, good sizing agents are obtained only when the OC methylstyrene-maleic anhydride copolymer is first reacted with primary amines containing 1 to 6 carbon atoms.

_ 2 -

containing atoms, is converted into the corresponding half-amide polymers »

The paper glues described in both patents, however, are limited in their application, since they lose their effect completely in a slightly alkaline medium.

Object of the invention

The aim of the invention is to produce alkali -resistant surface glues for paper and cardboard of various types and quality based on öC -Methylstyren -Haleinsäureanhydrid copolymers.

Explanation of the essence of the invention

The invention is based on the object from alternately constructed D6-methylstyrene-Maieinsäureanhydrid gopolymers having molecular weights of 800 to 20,000, by targeted esterification, optionally under low pressure to produce polymer solutions used as sizing agents for papers and cardboard in the acidic, neutral and weak alkaline range.

The object is achieved in that alternately structured O ^ -Methylstyren-maleic anhydride copolymers in alcohols having 1 to 3 carbon atoms are dissolved at temperatures between 330 K and 430 K, then by adding 0.2 to 0 * 6 moles of a Epoxy compound is further esterified per mole of carboxyl groups formed at temperatures between 370 and 450 K in the presence of a tertiary amine as an accelerator and 0.8 to 0.4 moles of ammonia per mole of starting anhydride groups in the form of an aqueous solution is added. It is surprising that a chemical modification of alternating O ^ -methylstyrene-maleic acid ^;

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Anbydrid copolymers first with C ₁ to C ~~ alcohols with half ester formation and subsequent partial esterification of the carboxyl groups formed with epoxides to form 2-hydroxyalkyl ester structural elements to polymers that form homogeneous aqueous-alcoholic solutions in the form of ammonium salts and as a sizing agent for Paper and cardboard against acidic, neutral and weakly alkaline media act.

There are used α-C-methylstyrene-maleic anhydride copolymers having an alternating structure. The preparation of this copolymer can be carried out by known methods of radical polymerization. The chemical modification of the OC-methylstyrene ~ maleic anhydride copolymers is carried out in alcohols containing 1 to 3 carbon atoms, such as methanol, ethanol, n-propanol or isopropanol, being depressurized at the boiling point of the corresponding alcohol, but preferably under pressure at temperatures esterification is the esterification is the use of alcohol mixtures, wherein an alcohol component is isopropanol. As a result of this reaction, CC-methylstyrene-maleic acid half-ester copolymers are obtained as alcoholic solutions with pesticide contents between 30 and 70 %, but in particular between 40 and 60 % . According to the invention, 20 to 60 mol% of the carboxyl groups formed in the half-ester formation are then additionally esterified by reaction with epoxides. This epoxide addition is advantageously carried out immediately after the half-esterification in the same reaction vessel, wherein tertiary amines are added as reaction accelerator. "The epoxides preferably used for the esterification of the carboxyl groups are ethylene oxide, propylene oxide and glycidyl ether of the general formula RO-CH ₂ ~ QH-CH ₂ , where R = Alkyl group having 1 to 8 C atoms with 1 to 8 C atoms or a phenyl group, such as methyl glycidyl ether,

230 0 9 8 /

Ethyl glycidyl ether, propyl glycidyl ether, isobutyl glycidyl ether, 2-ethylhexyl glycidyl ether and phenyl glycidyl ether. To accelerate the addition reaction, tertiary amines are added in amounts of 0.1 to 10 mol %, preferably 0.5 to 5 mol %, based on the spoxide, preferably trimethylamine, triethylamine, triisopropylamine and triisobutylamine.

As a result of the above chemical modification, Ct methylstyrene maleic acid ester copolymers containing alkyl diesters, hydroxyalkyl esters and carboxyl groups in the side chain are obtained as alcoholic solutions. The addition of aqueous ammonia produces the sizing agents which can be used, with aqueous-alcoholic solutions having polymer contents of between 15 and 25 %, but preferably 20%, being obtained. The glue solutions according to the invention have an anionic character. They are dilutable with water in all proportions, with anionic s paper auxiliaries, such as starch or carboxymethylcellulose but also with conventional optical brighteners, compatible. The new sizing agents are preferably used for surface sizing, whereby a combination with starch is possible. When using starch, the sizing effect in the acidic or neutral region is not additionally improved. In the weakly alkaline range, a more favorable sizing effect is achieved when using starch.

The sizing agents are used as 0.1 to 1.5 % solutions. They are suitable for gluing unsized or pre-glued, wood-free and wood-containing papers and cartons. To obtain sufficient sizing, application amounts of at least 0.09 g of pesticide / m 2 of paper surface are required to render the paper resistant to acidic and neutral inks To provide sufficient resistance to alkaline liquids with pH values between 7.5 and 12 are JPeststoffmengen from 0.8 to

2 Apply 1.2 g / m to the paper if no additional starch is used; in combination with starch, a polymer application of 0.4 g / m ² is sufficient. An increase in the amount of sizing agent applied further improves the alkaline strength.

embodiments

Example 1 ·

In a 20 1 stirred autoclave 2.16 kg of a -OS-methyl-1-styrene-maleic anhydride copolymer having a relative molecular weight of 6000 in a mixture of 1.1 1 n-propanol and 3.5 1 isopropanol with stirring for 8 hours This reaction time is followed by a homogeneous solution, to which 270 g of propylenoside and 22 g of triethylamine are metered in. After a further 6 hours reaction time, a homogeneous solution is obtained at temperatures of 403 to 405 K, the mixture is cooled to 348 to 353 K and set a nitrogen pressure of O ₅ 05 MPa.After stirring, a mixture of 8.1 1 of water and 0.102 kg of ammonia is added within 10 minutes After a reaction time of 330 " to 335 K, a 20% homogeneous solution of the modified copolymer as ammonium salt has formed after 30 minutes, clay of this stock solution becomes half with water To a solids content of 0.6 % and the other half diluted to a polymer content of 0.6% with 5% starch solution. Both solutions were used to form a non-sized, 76 g / m base paper on a size press of a pilot paper machine surface sized. Both solutions give Albrecht sizing degrees of f = 1.1 over acidic and neutral inks and sizing levels over a 2.5% soda solution of f = 15 without the use of starch solution and f = 3.1 when using starch solution.

Example 2

The procedure is as in the example given in Example 1. However, instead of propylene oxide, 210 g of ethylene oxide is used. It also gives a 20% i = e stock solution, half of which is diluted with water and the rest with a "5% strength solution to a polymer content of 0.8 % · Both solutions give Leimungsgra.de of f = 0.9 against acidic and neutral inks and against a 2.5% soda solution of f = 11 when diluted with water and f _% = 3.3 when diluted with starch solution

Example 3

In a 20 1 stirred autoclave 2.16 kg of an ÖC methyl

styrene-maleic anhydride copolymers in 4.37 l of methanol and stirred under a nitrogen pressure of 0.9 MPa for 7 hours ^ at a temperature of 405 K. Thereafter, 650 g Jsobutylglyc.idäther and 25 g of triethylamine are added and the temperature increased to 408 to 410 K. After a reaction time of 6 hours, the addition of the epoxide compound is complete. Ss is adjusted to a temperature of 343 K and a nitrogen overpressure of 0.05 MPa. At this temperature, a mixture of 9.3 1 of water and 0.09 kg of ammonia is added within 10 minutes. The mixture is stirred for 30 minutes at a temperature of 335 K, whereby a 20% solution of the modified copolymer in the form of the ammonium salt is formed. Half of this stamen solution is mixed with water and the remainder with 8% starch solution to a polymer content of. 0, 5 % diluted. With both solutions, a presized wood-free raw paper (degree of sizing according to Albrecht with f = with a weight of 84 g / m is surface-glued on a laboratory size press.) Both gluing solutions give Albrecht sizing degrees of f = 0.9 to 1.1 compared to neutral test ink and Sizing compared to a 2.5%

Soda solution of f = 14 without use of starch and P = 4.1 when using starch *

Example 4

It is worked according to the rule mentioned in Example 3. However, instead of methanol, 4.5 liters of ethanol are used. A 20% strength solution of the modified copolymer in the form of the ammonium salt is obtained which, after dilution with a 5% strength solution to a polymer content of 1.0 %, is used for surface sizing of a non-presized wood-containing material Raw paper weighing 58 g / m is used. One obtains a degree of sizing according to Albrecht of f = 0 _? 9 versus acid and neutral inks and f = 4.7 versus a 2.5% soda solution.

Claims (3)

invention claim 1. A process for preparing alkali-free Papierleimlos'ungen based on OC-methylstyrene-maleic anhydride "copolymers having relative molecular weights of 800 to 20,000 by selective esterification, optionally under pressure, characterized in that , , the alternating copolymers are dissolved in alcohols containing 1 to 3 carbon atoms at temperatures between 330 K and 430 K. - Then by addition of 0.2 to 0.6 moles of an epoxy compound per mole of carboxyl groups formed at temperatures between 370 K and 450 K in the presence of a tert. Amines are further esterified as accelerators and - 0.8 to 0.4 moles of aqueous ammonia ₍ per mole of starting anhydride groups, is added. 2. The method according to item 1, characterized in that as epoxides ethylene oxide, propylene oxide or glycidyl ether of the general formula R - O - CH ₀ - CH - CH ₀ can be used, ά \ / ^Δ wherein R represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. 3. The method according to item 1, characterized in that tertiary amines trimethylamine, triethylamine, Triisoprcpylamin or triisobutylamine are used.