CA2145286C - Use of hydrolysed copolymers of n-vinyl carboxylic acid amides and monoethylenically unsaturated carboxylic acids in the manufacture of paper - Google Patents
Use of hydrolysed copolymers of n-vinyl carboxylic acid amides and monoethylenically unsaturated carboxylic acids in the manufacture of paper Download PDFInfo
- Publication number
- CA2145286C CA2145286C CA002145286A CA2145286A CA2145286C CA 2145286 C CA2145286 C CA 2145286C CA 002145286 A CA002145286 A CA 002145286A CA 2145286 A CA2145286 A CA 2145286A CA 2145286 C CA2145286 C CA 2145286C
- Authority
- CA
- Canada
- Prior art keywords
- mol
- copolymer
- groups
- copolymers
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/44—Preparation of metal salts or ammonium salts
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/06—Paper forming aids
- D21H21/10—Retention agents or drainage improvers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2800/00—Copolymer characterised by the proportions of the comonomers expressed
- C08F2800/20—Copolymer characterised by the proportions of the comonomers expressed as weight or mass percentages
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2810/00—Chemical modification of a polymer
- C08F2810/50—Chemical modification of a polymer wherein the polymer is a copolymer and the modification is taking place only on one or more of the monomers present in minority
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Paper (AREA)
Abstract
Use of copolymers which are obtainable by copolymerization of a) from 5 to 99 mol% of N-vinylcarboxamides, b) from 95 to 1 mol% of monoethylenically unsaturated carboxylic acids and/or the alkali metal, alkaline earth metal, ammonium or amine salts thereof and, if required, c) up to 30 mol% of other monoethylenically unsaturated com-pounds and, if required, d) up to 2 mol% of crosslinking agents and subsequent partial or complete elimination of the formyl groups from the N-vinylcarboxamides polymerized in the copolymer, with formation of amino or ammonium groups, are used as additives to paper stock for increasing the drainage rate and the retention in papermaking and the dry and wet strength of the paper.
Description
0050/43722 ~ 14 ~ 2 8 ~
Use of hydrolyzed copolymers of N-vinylcarboxamides and monoethy-lenically unsaturated carboxylic acids in papermaking The present invention relates to the use of copolymers which are obtainable by copolymerization of N-vinylcarboxamides with other monoethylenically unsaturated compounds and partial or complete elimination of formyl groups from the N-vinylcarboxamides poly-merized in the copolymer, with formation of amino or ammonium groups, as additives to paper stock for increasing the drainage rate and retention in papermaking and the dry and wet strength of the paper.
US-A-2 721 140 discloses the use of polyvinylamine hydrochloride as an assistant in papermaking, in particular papers having high wet strength being obtained. However, the paper treated in this manner has a relatively high tendency to yellow.
US-4 421 602 discloses partially hydrolyzed, water-soluble homo-polymers of N-vinylformamide which contain N vinylformamide units and vinylamine units. These polymers are used as agents for increasing the flocculation, retention and drainage rate in papermaking.
EP-A-0 438 744 discloses copolymers which contain, as polymerized units, from 99 to 50$ by weight of at least one monoethylenically unsaturated carboxylic acid of 3 to 8 carbon atoms or salts thereof and from 1 to 50~ by weight of N-vinylcarboxamides, pre-ferably N vinylformamide, and which have been subjected to hydro-lysis in which the formyl groups of the N vinylcarboxamides are eliminated with formation of amino or ammonium groups. These copolymers are used as water treatment agents for reducing lime-scale and water hardness deposits in water-conveying systems and in the concentration of sugar juice.
EP-A-0 216 387 discloses water-soluble copolymers which contain vinylamine units and are obtainable by copolymerization of N vi-nylformamide with monoethylenically unsaturated monomers selected from the group consisting of vinyl acetate, vinyl propionate, C1-to C~-alkyl vinyl ethers, the esters, nitriles and amides of acrylic acid and methacrylic acid and N vinylpyrrolidone and elimination of the formyl groups from the copolymers. These copolymers and, preferably, copolymers of N-vinylformamide and vinyl acetate, from 30 to 100 mold of whose monomer units are hydrolyzed in each case, are used as agents for increasing the dry and wet strength of paper.
AMENDED SHEET
' 0050/43722 EP-B-0 251-182 discloses copolymers which contain vinylamine groups in salt form, vinylformamide groups and acrylonitrile groups and, a-f requited, acrylamide and acrylic acid groups. The amount of polymerized acrylic acid or methacrylic acid is not 5 more than 6.4 moI%. These copolymers are used in papermaking and act as drainage and retention agents and as agents for increasing the dry strength of paper.
It is an object of the present invention to provide a further 10 paper aid which, when added to the paper stock, leads to an increase in the mechanical strengths of the papers thus produced and at the same time increases the drainage rate and retention.
We have found that this object is achieved, according to the 15 invention, by the use of copolymers which are obtainable by copolymerization of a) from 5 to 99 mol% of N vinylcarboxamides of the formula CH2- CH-N~
~C-Rl tI) r O
where R1 and R~ are each H or C1--C6-alkyl, b) from 95 to 1 mol% of monoethylenically unsaturated carboxylic acids of 3 to 8 carbon atoms and/or the alkali metal and ammonium salts thereof and, if required, c) up to 30 mol% of vinyl acetate, N-vinylpyrrolidone or N-viny-limidazole or mixtures thereof and, if required, d) up to 2 mol% of compounds which have at least two ethyleni-cally unsaturated nonconjugated double bonds in the molecule, and subsequent partial or complete elimination of O
AMENDED SHEET
Use of hydrolyzed copolymers of N-vinylcarboxamides and monoethy-lenically unsaturated carboxylic acids in papermaking The present invention relates to the use of copolymers which are obtainable by copolymerization of N-vinylcarboxamides with other monoethylenically unsaturated compounds and partial or complete elimination of formyl groups from the N-vinylcarboxamides poly-merized in the copolymer, with formation of amino or ammonium groups, as additives to paper stock for increasing the drainage rate and retention in papermaking and the dry and wet strength of the paper.
US-A-2 721 140 discloses the use of polyvinylamine hydrochloride as an assistant in papermaking, in particular papers having high wet strength being obtained. However, the paper treated in this manner has a relatively high tendency to yellow.
US-4 421 602 discloses partially hydrolyzed, water-soluble homo-polymers of N-vinylformamide which contain N vinylformamide units and vinylamine units. These polymers are used as agents for increasing the flocculation, retention and drainage rate in papermaking.
EP-A-0 438 744 discloses copolymers which contain, as polymerized units, from 99 to 50$ by weight of at least one monoethylenically unsaturated carboxylic acid of 3 to 8 carbon atoms or salts thereof and from 1 to 50~ by weight of N-vinylcarboxamides, pre-ferably N vinylformamide, and which have been subjected to hydro-lysis in which the formyl groups of the N vinylcarboxamides are eliminated with formation of amino or ammonium groups. These copolymers are used as water treatment agents for reducing lime-scale and water hardness deposits in water-conveying systems and in the concentration of sugar juice.
EP-A-0 216 387 discloses water-soluble copolymers which contain vinylamine units and are obtainable by copolymerization of N vi-nylformamide with monoethylenically unsaturated monomers selected from the group consisting of vinyl acetate, vinyl propionate, C1-to C~-alkyl vinyl ethers, the esters, nitriles and amides of acrylic acid and methacrylic acid and N vinylpyrrolidone and elimination of the formyl groups from the copolymers. These copolymers and, preferably, copolymers of N-vinylformamide and vinyl acetate, from 30 to 100 mold of whose monomer units are hydrolyzed in each case, are used as agents for increasing the dry and wet strength of paper.
AMENDED SHEET
' 0050/43722 EP-B-0 251-182 discloses copolymers which contain vinylamine groups in salt form, vinylformamide groups and acrylonitrile groups and, a-f requited, acrylamide and acrylic acid groups. The amount of polymerized acrylic acid or methacrylic acid is not 5 more than 6.4 moI%. These copolymers are used in papermaking and act as drainage and retention agents and as agents for increasing the dry strength of paper.
It is an object of the present invention to provide a further 10 paper aid which, when added to the paper stock, leads to an increase in the mechanical strengths of the papers thus produced and at the same time increases the drainage rate and retention.
We have found that this object is achieved, according to the 15 invention, by the use of copolymers which are obtainable by copolymerization of a) from 5 to 99 mol% of N vinylcarboxamides of the formula CH2- CH-N~
~C-Rl tI) r O
where R1 and R~ are each H or C1--C6-alkyl, b) from 95 to 1 mol% of monoethylenically unsaturated carboxylic acids of 3 to 8 carbon atoms and/or the alkali metal and ammonium salts thereof and, if required, c) up to 30 mol% of vinyl acetate, N-vinylpyrrolidone or N-viny-limidazole or mixtures thereof and, if required, d) up to 2 mol% of compounds which have at least two ethyleni-cally unsaturated nonconjugated double bonds in the molecule, and subsequent partial or complete elimination of O
AMENDED SHEET
from the monomers I polymerized in the copolymer, with formation of amino or ammonium groups, as additives to paper stock for in-creasing the drainage rate and the retention in papermaking and the dry and wet strength of the paper.
The copolymers to be used according to the invention are prepared by free radical copolymerization of N vinylcarboxamides and mono-ethylenically unsaturated carboxylic acids, preferably acrylic acid and/or methacrylic acid, and salts thereof and, if required, other monoethylenically unsaturated monomers. The copolymeriza-tion may be carried out, if required, additionally in the pres-ence of crosslinking agents.
Suitable monomers of group a) are N-vinylcarboxamides of the for-mula CHy- CH-N~
~C-Rl CI).
O
where R1 and R2 are each H or C1-C6-alkyl. Examples of suitable monomers are N vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N vinyl-N~nethylacetamide, N vinyl-N-ethyl-acetamide, N-vinyl-N~nethylpropionamide and N-vinylpropionamide.
For the preparation of the copolymers, the stated monomers may be used either alone or as a mixture with one another. From this group of monomers, N-vinylformamide is preferably used. The copolymers contain the monomers of group a) in amounts of from 5 to 99, preferably from 30 to 95, mol% in polymerized form.
Suitabre monomers of group b) are monoethylenically unsaturated carboxylic acids of 3 to 8 carbon atoms and the water-soluble salts of these monomers. This group of monomers includes, for example, acrylic acid, methacrylic acid, dimethylacrylic acid, ethacrylic acid, malefic acid, citraconic acid, methylenemalonic acid, allylacetic acid, vinylacetic acid, crotonic acid, fumaric acid, mesaconic acid and itaconic acid. From this group of mono-mers, acrylic acid, methacrylic acid, malefic acid or mixtures of the stated carboxylic acids, in particular mixtures of acrylic acid and malefic acid or mixtures of acrylic acid and methacrylic acid, are preferably used. The monomers of group b) may be used either in the form of the free carboxylic acids or in partially or completely neutralized form in the copolymerization. The mono-ethylenically unsaturated carboxylic acids are neutralized using, for example, alkali metal or alkaline earth metal bases, ammonia AMENDED SHEET
The copolymers to be used according to the invention are prepared by free radical copolymerization of N vinylcarboxamides and mono-ethylenically unsaturated carboxylic acids, preferably acrylic acid and/or methacrylic acid, and salts thereof and, if required, other monoethylenically unsaturated monomers. The copolymeriza-tion may be carried out, if required, additionally in the pres-ence of crosslinking agents.
Suitable monomers of group a) are N-vinylcarboxamides of the for-mula CHy- CH-N~
~C-Rl CI).
O
where R1 and R2 are each H or C1-C6-alkyl. Examples of suitable monomers are N vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N vinyl-N~nethylacetamide, N vinyl-N-ethyl-acetamide, N-vinyl-N~nethylpropionamide and N-vinylpropionamide.
For the preparation of the copolymers, the stated monomers may be used either alone or as a mixture with one another. From this group of monomers, N-vinylformamide is preferably used. The copolymers contain the monomers of group a) in amounts of from 5 to 99, preferably from 30 to 95, mol% in polymerized form.
Suitabre monomers of group b) are monoethylenically unsaturated carboxylic acids of 3 to 8 carbon atoms and the water-soluble salts of these monomers. This group of monomers includes, for example, acrylic acid, methacrylic acid, dimethylacrylic acid, ethacrylic acid, malefic acid, citraconic acid, methylenemalonic acid, allylacetic acid, vinylacetic acid, crotonic acid, fumaric acid, mesaconic acid and itaconic acid. From this group of mono-mers, acrylic acid, methacrylic acid, malefic acid or mixtures of the stated carboxylic acids, in particular mixtures of acrylic acid and malefic acid or mixtures of acrylic acid and methacrylic acid, are preferably used. The monomers of group b) may be used either in the form of the free carboxylic acids or in partially or completely neutralized form in the copolymerization. The mono-ethylenically unsaturated carboxylic acids are neutralized using, for example, alkali metal or alkaline earth metal bases, ammonia AMENDED SHEET
or amines,-for example sodium hydroxide solution, potassium hydroxide solution, sodium carbonate, potassium carbonate, sodium bicarbonate, magnesium oxide, calcium hydroxide, calcium oxide, ammonium, triethylamine, ethanolamine, diethanolamine, tri-ethanolamine, morpholine, diethylenetriamine or tetraethylene-pentamine. The copolymers contain the monomers of group b) in an amount of from 95 to 1, preferably from 70 to 5, mold in poly-merized form.
The copolymers of the monomers a) and b) can, if required, be modified by using in the copolymerization other monoethylenically unsaturated compounds which are copolymerizable with the monomers a) and b). Examples of suitable monomers of group c) are the esters, amides and nitriles of the carboxylic acids stated under a), for example methyl acrylate, ethyl acrylate, methyl methacry-late, ethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyisobutyl acrylate, hydroxyiso-butyl methacrylate, monomethyl maleate, dimethyl maleate, mono-ethyl maleate, diethyl maleate, 2-ethylhexyl acrylate, 2-ethyl-hexyl methacrylate, acrylamide, methacrylamide, N~iimethylacryl-amide, N-tert-butylacrylamide, acrylonitrile, methacrylonitrile, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate or diethylaminoethyl methacrylate, and the salts of the last-mentioned monomers with carboxylic acids or mineral acids and the quaternized products. Other suitable mono-mers of group c) are acrylamidoglycolic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate and acrylami-domethylpropanesulfonic acid and monomers containing phosphonic acid groups, such as vinyl phosphate, allyl phosphate and acryl-amidomethylpropanephosphonic acid. Further suitable compounds of this group are N-vinylpyrrolidone, N-vinylcaprolactam, N vi-nyl-2-methylimidazoline, diallylammonium chloride, vinyl acetate and vinyl propionate. It is of course also possible to use mix-tures of the stated monomers of group c), for example mixtures of acrylates and vinyl acetate, mixtures of different acrylates, mixtures of acrylates and acrylamides or mixtures of acrylamide and hydroxyethyl acrylate. Among the monomers of group c), acrylamide, acrylonitrile, vinyl acetate, N vinylpyrrolidone, N-vinylimidazole or mixtures of these monomers, for example mix-tures of acrylamide and vinyl acetate or mixtures of acrylamide and acrylonitrile, are preferably used. If the monomers of group c) are used for modifying the copolymers, they are present in the copolymers in polymerized form in amounts of up to 30, preferably from 1 to 20, mold.
The copolymers of the monomers a) and b) and, if required, c) may furthermore be modified by carrying out the copolymerization in the presence of monomers of group d), which are compounds which have at least two ethylenically unsaturated nonconjugated double 5 bonds in the molecule. The presence of the monomers of group d) in the copolymerization results in an increase in the K values of the copolymers. Examples of suitable compounds of group d) are methylenebisacrylamide, esters of acrylic acid and methacrylic acid with polyhydric alcohols, such as glycol diacrylate, gly-ceryl triacrylate, glycol dimethacrylate or glyceryl trimethacry-late, and polyethylene glycols or polyols, such as pentaerythri-tol and glucose, which are at least diesterified with acrylic acid or methacrylic acid. Other suitable crosslinking agents are divinylbenzene, divinyldioxane, pentaerythrityl triallyl ether and pentaallylsucrose. Water-soluble monomers, such as glycol diacrylate or glycol diacrylates of polyethylene glycols having a molecular weight of up to 3000, are preferably used from this group. If the monomers of group d) are used for modifying the copolymers, the amounts employed are up to 2 mol%. Where they are used, they are preferably present in the copolymers in poly-merized form in an amount of from 0.01 to 1 mol%.
It is preferable to use the compounds which are obtainable by copolymerization of a) from 30 to 95 mol% of N vinylformamide, b) from 70 to 5 mol% of acrylic acid, methacrylic acid and/or the alkali metal, alkaline earth metal, ammonium or amine salts thereof and c) from 0 to 30 mol% of acrylamide, acrylonitrile, vinyl ace-tate, N-vinylpyrrolidone, N vinylimidazole or mixtures there-of, and subsequent partial or complete hydrolysis of the polymerized N-vinylformamide units, for example copolymers of N-vinylformamide, acrylic acid and acrylamide, copolymers of N vinylformamide, acrylic acid and acrylonitrile, copolymers of N vinylformamide, acrylic acid and vinylacetate, copoly-mers of N-vinylformamide, acrylic acid and N vinylpyrroli-done, copolymers of N vinylformamide, acrylic acid, acrylo-nitrile and vinyl acetate, and copolymers of N-vinylforma-mide, acrylic acid, acrylamide and acrylonitrile. In the copolymers last described, some or all of the acrylic acid may be replaced by methacrylic acid. Acrylic acid or meth-acrylic acid may be partially or completely neutralized with 214~2~88 sodium hydroxide solution, potassium hydroxide solution, cal-cium hydroxide or ammonia.
The copolymers are prepared by known processes, for example solu-tion, precipitation, suspension or emulsion polymerization, using compounds which form free radicals under the polymerization conditions. The polymerization temperatures are usually from 30 to 200~C, preferably from 40 to 110~C. Examples of suitable initiators are azo and peroxy compounds and the conventional redox initiator systems, such as combinations of hydrogen peroxide and reducing compounds, eg. sodium sulfite, sodium bisulfate, sodium formaldehyde sulfoxylate and hydrazine. These systems can, if required, additionally contain small amounts of a heavy metal salt.
The copolymers are preferably prepared by solution polymerization in water, the monomers of group b) preferably being used in salt form and the pH being kept at from 6 to 8 during the polymeriza-tion. In order to keep the pH constant during the copolymeriza-tion, it is advantageous to add small amounts, for example from 0.5 to 2% by weight, of a buffer, for example disodium hydrogen phosphate. Preferably used polymerization initiators are water-soluble azo compounds, such as 2,2'-azobis(2-methylpropion-amidine) dihydrochloride, 2,2'-azobis(4-methoxy-2,4-dimethylval-eronitrile) and 2,2'-azobis(2-methyl-N-phenylpropionamidine) di-hydrochloride.
In order to prepare low molecular weight copolymers, the copoly-merization is carried out in the presence of a regulator. Exam-ples of suitable regulators are secondary alcohols, such as iso-propanol and sec-butanol, hydroxylamine, formic acid and mercapto compounds, such as mercaptoethanol, mercaptopropanol, mercaptobu-tanol,-~hioglycolic acid, thiolactic acid, tert-butyl mercaptan, octyl mercaptan and dodecyl mercaptan. The regulators are usually used in amounts of from 0.01 to 5% by weight, based on the mono-mers used. If secondary alcohols are used as regulators, the polymerization may also be carried out in the presence of sub-stantially larger amounts, for example up to 80% by weight, based on the monomers. In these cases, the secondary alcohols are simultaneously solvents for the monomers.
The copolymers thus obtainable have K values of from 30 to 300, preferably from 50 to 250. The K values are determined according to H. Fikentscher, in 5% strength aqueous sodium chloride solu-tion at pH 7, 25'C and a polymer concentration of 0.1% by weight.
The copolymers of the monomers a) and b) can, if required, be modified by using in the copolymerization other monoethylenically unsaturated compounds which are copolymerizable with the monomers a) and b). Examples of suitable monomers of group c) are the esters, amides and nitriles of the carboxylic acids stated under a), for example methyl acrylate, ethyl acrylate, methyl methacry-late, ethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyisobutyl acrylate, hydroxyiso-butyl methacrylate, monomethyl maleate, dimethyl maleate, mono-ethyl maleate, diethyl maleate, 2-ethylhexyl acrylate, 2-ethyl-hexyl methacrylate, acrylamide, methacrylamide, N~iimethylacryl-amide, N-tert-butylacrylamide, acrylonitrile, methacrylonitrile, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate or diethylaminoethyl methacrylate, and the salts of the last-mentioned monomers with carboxylic acids or mineral acids and the quaternized products. Other suitable mono-mers of group c) are acrylamidoglycolic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate and acrylami-domethylpropanesulfonic acid and monomers containing phosphonic acid groups, such as vinyl phosphate, allyl phosphate and acryl-amidomethylpropanephosphonic acid. Further suitable compounds of this group are N-vinylpyrrolidone, N-vinylcaprolactam, N vi-nyl-2-methylimidazoline, diallylammonium chloride, vinyl acetate and vinyl propionate. It is of course also possible to use mix-tures of the stated monomers of group c), for example mixtures of acrylates and vinyl acetate, mixtures of different acrylates, mixtures of acrylates and acrylamides or mixtures of acrylamide and hydroxyethyl acrylate. Among the monomers of group c), acrylamide, acrylonitrile, vinyl acetate, N vinylpyrrolidone, N-vinylimidazole or mixtures of these monomers, for example mix-tures of acrylamide and vinyl acetate or mixtures of acrylamide and acrylonitrile, are preferably used. If the monomers of group c) are used for modifying the copolymers, they are present in the copolymers in polymerized form in amounts of up to 30, preferably from 1 to 20, mold.
The copolymers of the monomers a) and b) and, if required, c) may furthermore be modified by carrying out the copolymerization in the presence of monomers of group d), which are compounds which have at least two ethylenically unsaturated nonconjugated double 5 bonds in the molecule. The presence of the monomers of group d) in the copolymerization results in an increase in the K values of the copolymers. Examples of suitable compounds of group d) are methylenebisacrylamide, esters of acrylic acid and methacrylic acid with polyhydric alcohols, such as glycol diacrylate, gly-ceryl triacrylate, glycol dimethacrylate or glyceryl trimethacry-late, and polyethylene glycols or polyols, such as pentaerythri-tol and glucose, which are at least diesterified with acrylic acid or methacrylic acid. Other suitable crosslinking agents are divinylbenzene, divinyldioxane, pentaerythrityl triallyl ether and pentaallylsucrose. Water-soluble monomers, such as glycol diacrylate or glycol diacrylates of polyethylene glycols having a molecular weight of up to 3000, are preferably used from this group. If the monomers of group d) are used for modifying the copolymers, the amounts employed are up to 2 mol%. Where they are used, they are preferably present in the copolymers in poly-merized form in an amount of from 0.01 to 1 mol%.
It is preferable to use the compounds which are obtainable by copolymerization of a) from 30 to 95 mol% of N vinylformamide, b) from 70 to 5 mol% of acrylic acid, methacrylic acid and/or the alkali metal, alkaline earth metal, ammonium or amine salts thereof and c) from 0 to 30 mol% of acrylamide, acrylonitrile, vinyl ace-tate, N-vinylpyrrolidone, N vinylimidazole or mixtures there-of, and subsequent partial or complete hydrolysis of the polymerized N-vinylformamide units, for example copolymers of N-vinylformamide, acrylic acid and acrylamide, copolymers of N vinylformamide, acrylic acid and acrylonitrile, copolymers of N vinylformamide, acrylic acid and vinylacetate, copoly-mers of N-vinylformamide, acrylic acid and N vinylpyrroli-done, copolymers of N vinylformamide, acrylic acid, acrylo-nitrile and vinyl acetate, and copolymers of N-vinylforma-mide, acrylic acid, acrylamide and acrylonitrile. In the copolymers last described, some or all of the acrylic acid may be replaced by methacrylic acid. Acrylic acid or meth-acrylic acid may be partially or completely neutralized with 214~2~88 sodium hydroxide solution, potassium hydroxide solution, cal-cium hydroxide or ammonia.
The copolymers are prepared by known processes, for example solu-tion, precipitation, suspension or emulsion polymerization, using compounds which form free radicals under the polymerization conditions. The polymerization temperatures are usually from 30 to 200~C, preferably from 40 to 110~C. Examples of suitable initiators are azo and peroxy compounds and the conventional redox initiator systems, such as combinations of hydrogen peroxide and reducing compounds, eg. sodium sulfite, sodium bisulfate, sodium formaldehyde sulfoxylate and hydrazine. These systems can, if required, additionally contain small amounts of a heavy metal salt.
The copolymers are preferably prepared by solution polymerization in water, the monomers of group b) preferably being used in salt form and the pH being kept at from 6 to 8 during the polymeriza-tion. In order to keep the pH constant during the copolymeriza-tion, it is advantageous to add small amounts, for example from 0.5 to 2% by weight, of a buffer, for example disodium hydrogen phosphate. Preferably used polymerization initiators are water-soluble azo compounds, such as 2,2'-azobis(2-methylpropion-amidine) dihydrochloride, 2,2'-azobis(4-methoxy-2,4-dimethylval-eronitrile) and 2,2'-azobis(2-methyl-N-phenylpropionamidine) di-hydrochloride.
In order to prepare low molecular weight copolymers, the copoly-merization is carried out in the presence of a regulator. Exam-ples of suitable regulators are secondary alcohols, such as iso-propanol and sec-butanol, hydroxylamine, formic acid and mercapto compounds, such as mercaptoethanol, mercaptopropanol, mercaptobu-tanol,-~hioglycolic acid, thiolactic acid, tert-butyl mercaptan, octyl mercaptan and dodecyl mercaptan. The regulators are usually used in amounts of from 0.01 to 5% by weight, based on the mono-mers used. If secondary alcohols are used as regulators, the polymerization may also be carried out in the presence of sub-stantially larger amounts, for example up to 80% by weight, based on the monomers. In these cases, the secondary alcohols are simultaneously solvents for the monomers.
The copolymers thus obtainable have K values of from 30 to 300, preferably from 50 to 250. The K values are determined according to H. Fikentscher, in 5% strength aqueous sodium chloride solu-tion at pH 7, 25'C and a polymer concentration of 0.1% by weight.
The hydrolyzed copolymers to be used according to the invention are obtained, with formation of amino or ammonium groups, from the copolymers described above, by partial or complete elimina-tion of the formyl groups from the monomers I polymerized in the copolymer:
Hydrolysis ,\ ,\
O
(II) (III) In the formulae (II) and (III), R1 and Rz each have the meanings stated in formula (I). Depending on the reaction conditions cho-sen in the hydrolysis, either partial or complete hydrolysis of the units II is obtained. The hydrolysis is continued so that from 30 to 100, preferably from 60 to 95, % of the monomers a) polymerized in the copolymer are hydrolyzed. In the case of the hydrolysis of copolymers containing vinylformamide units, the degree of hydrolysis can be determined, for example, by polyelec-trolyte titration or by enzymatic analysis of the liberated for-mic acid. If the copolymers contain polymerized monomers of group c) in addition to the monomers a) and b), the polymerized mono-mers c) may also be chemically changed, depending on the chosen hydrolysis conditions; for example, vinyl alcohol units are formed from vinyl acetate units, acrylic acid units from methyl acrylate units, and acrylamide or acrylic acid units from acrylo-nitrile units. The degree of hydrolysis of the abovementioned units II is preferably from 60 to 95%.
Particularly suitable hydrolysis agents are mineral acids, such as hydrogen halide, which can be used in gaseous form or in aqueous solution. Hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid and organic acids, such as C1-C5-carboxylic acids and aliphatic or aromatic sulfonic acids, are preferably used. The pH in the acidic hydrolysis is from -1 to 5, preferably from 0 to 2. From 0.05 to 2, preferably from 1 to 1.5, mole equivalents of an acid are required per equivalent of formyl groups which is to be eliminated from the polymerized units II.
Hydrolysis ,\ ,\
O
(II) (III) In the formulae (II) and (III), R1 and Rz each have the meanings stated in formula (I). Depending on the reaction conditions cho-sen in the hydrolysis, either partial or complete hydrolysis of the units II is obtained. The hydrolysis is continued so that from 30 to 100, preferably from 60 to 95, % of the monomers a) polymerized in the copolymer are hydrolyzed. In the case of the hydrolysis of copolymers containing vinylformamide units, the degree of hydrolysis can be determined, for example, by polyelec-trolyte titration or by enzymatic analysis of the liberated for-mic acid. If the copolymers contain polymerized monomers of group c) in addition to the monomers a) and b), the polymerized mono-mers c) may also be chemically changed, depending on the chosen hydrolysis conditions; for example, vinyl alcohol units are formed from vinyl acetate units, acrylic acid units from methyl acrylate units, and acrylamide or acrylic acid units from acrylo-nitrile units. The degree of hydrolysis of the abovementioned units II is preferably from 60 to 95%.
Particularly suitable hydrolysis agents are mineral acids, such as hydrogen halide, which can be used in gaseous form or in aqueous solution. Hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid and organic acids, such as C1-C5-carboxylic acids and aliphatic or aromatic sulfonic acids, are preferably used. The pH in the acidic hydrolysis is from -1 to 5, preferably from 0 to 2. From 0.05 to 2, preferably from 1 to 1.5, mole equivalents of an acid are required per equivalent of formyl groups which is to be eliminated from the polymerized units II.
The hydrolysis of the polymerized units of the structure II can also be carried out with the aid of bases, for example metal hydroxides, in particular alkali metal or alkaline earth metal hydroxides. Sodium hydroxide or potassium hydroxide is preferably used. The hydrolysis can, if required, also be carried out in the presence of ammonia or amines.
The hydrolysis of the copolymers in aqueous solution or suspen-sion at reaction temperatures of from 20 to 100°C has proven particularly suitable. If the unhydrolyzed copolymers are poorly soluble in water, they generally dissolve in the reaction medium as the hydrolysis progresses. After an acidic hydrolysis, the reaction mixture is, if required, neutralized with bases, prefer-ably sodium hydroxide solution. If the hydrolysis has been car-ried out using a base, the reaction mixture can, if required, be neutralized by adding an acid, preferably hydrochloric acid.
After the hydrolysis, the pH of the reaction mixture may be from 1 to 10, preferably from 3 to 8. Depending on the composition, the hydrolyzed copolymers may be poorly soluble in certain pH
ranges. The K value of the hydrolyzed copolymers is from 10 to 300, preferably from 15 to 200 (measured in 5% strength aqueous sodium chloride solution at a polymer concentration of 0.1% by weight, a pH of 1.5 and 25°C).
According to the invention, the hydrolyzed copolymers are used in papermaking. They are added to the paper stock in amounts of from 0.01 to 5, preferably from 0.1 to 2, % by weight, based on dry fibers. The hydrolyzed copolymers both increase the drainage rate and the retention in papermaking and at the same time increase the dry and wet strength of the paper.
The K values of the copolymers were determined according to H. Fikehtscher, Cellulosechemie, ~ (1932), 48-64 and 71-74, in 5% strength aqueous sodium chloride solution at 25°C and at a polymer concentration of 0.1% by weight, the K value of the unhy-drolyzed copolymers being measured at pH 7 and that of the hydro-lyzed copolymers at 1.5.
Examples Preparation of the copolymers Copolymer 1 991 g of distilled water, 1.54 g of 75% strength phosphoric acid and 1.06 g of 50% strength aqueous sodium hydroxide solution are heated to 70°C in a gentle stream of nitrogen in a polymerization 0050/43722 2 ~ 4,,5 2 8~~
The hydrolysis of the copolymers in aqueous solution or suspen-sion at reaction temperatures of from 20 to 100°C has proven particularly suitable. If the unhydrolyzed copolymers are poorly soluble in water, they generally dissolve in the reaction medium as the hydrolysis progresses. After an acidic hydrolysis, the reaction mixture is, if required, neutralized with bases, prefer-ably sodium hydroxide solution. If the hydrolysis has been car-ried out using a base, the reaction mixture can, if required, be neutralized by adding an acid, preferably hydrochloric acid.
After the hydrolysis, the pH of the reaction mixture may be from 1 to 10, preferably from 3 to 8. Depending on the composition, the hydrolyzed copolymers may be poorly soluble in certain pH
ranges. The K value of the hydrolyzed copolymers is from 10 to 300, preferably from 15 to 200 (measured in 5% strength aqueous sodium chloride solution at a polymer concentration of 0.1% by weight, a pH of 1.5 and 25°C).
According to the invention, the hydrolyzed copolymers are used in papermaking. They are added to the paper stock in amounts of from 0.01 to 5, preferably from 0.1 to 2, % by weight, based on dry fibers. The hydrolyzed copolymers both increase the drainage rate and the retention in papermaking and at the same time increase the dry and wet strength of the paper.
The K values of the copolymers were determined according to H. Fikehtscher, Cellulosechemie, ~ (1932), 48-64 and 71-74, in 5% strength aqueous sodium chloride solution at 25°C and at a polymer concentration of 0.1% by weight, the K value of the unhy-drolyzed copolymers being measured at pH 7 and that of the hydro-lyzed copolymers at 1.5.
Examples Preparation of the copolymers Copolymer 1 991 g of distilled water, 1.54 g of 75% strength phosphoric acid and 1.06 g of 50% strength aqueous sodium hydroxide solution are heated to 70°C in a gentle stream of nitrogen in a polymerization 0050/43722 2 ~ 4,,5 2 8~~
apparatus equipped with a stirrer. As soon as this temperature has been reached, in the course of 2 hours a solution of 50 g of water, 39.2 g of acrylic acid and 43.6 g of 50% strength aqueous sodium hydroxide solution, separately from this 160 g of N-vinyl-formamide and likewise separately from this a solution of 25 g of water and 0.05 g of 2,2'-azobis(2-methylpropionamidine) dihy-drochloride, are added uniformly. After the end of the monomer addition, a solution of 0.15 g of 2,2'-azobis(2-methylpropionami-dine) dihydrochloride in 73 g of water is metered in over 1 hour, and the reaction mixture is then stirred for a further 2 hours at 70°C and is then diluted with 800 g of water. The highly viscous solution thus obtainable has a solids content of 10.9% and a pH
of 6.2. The K value of the copolymer is 177.
Hydrolysis of the polymerized N vinylformamide of copolymer 1 500 g of the aqueous solution, described above, of a copolymer of 75.4% by weight of vinylformamide and 24.6% by weight of sodium acrylate, having a K value of 177, are initially taken in an apparatus equipped with a stirrer and are diluted with 250 g of water. The mixture is first stirred at room temperature, and 80.2 g of 38% strength hydrochloric acid are added in the course of 20 minutes. Thereafter, the reaction mixture is heated at 70°C
for 7 hours and is cooled to room temperature, and 120 g of a 10%
strength aqueous sodium hydroxide solution are added. The pH of the reaction mixture is then 1.5. In order to stabilize the reac-tion mixture, 15 g of 0.5% strength aqueous sodium bisulfite solution are added. The degree of hydrolysis of the polymerized N-vinylformamide is 93%. The solution has a polymer content of 5.8% by weight (hydrolyzed copolymer 1). The K value of the polymer is 135.
Copolymer 2 965.3 g of water, 1.34 g of a 75% strength aqueous phosphoric acid and 0.92 g of a 50% strength aqueous sodium hydroxide solu-tion are heated to 70°C in a stream of nitrogen in a polymeriza-tion apparatus. As soon as this temperature has been reached, a mixture of 100 g of water, 60 g of acrylic acid and 66.5 g of 50%
strength aqueous sodium hydroxide solution, separately from this 141.4 g of N vinylformamide and likewise separately from this a solution of 0.05 g of 2,2'-azobis(2~nethylpropionamidine) dihy-drochloride in 25 g of water are added uniformly, in each case in the course of 2 hours. After the end of the addition of initiator and monomers, a solution of 0.15 g of 2,2'-azobis(2~nethyl-propionamidine) dihydrochloride, dissolved in 73 g of water, is added in the course of 1 hour, the reaction mixture is kept at ~1~528~
i0 70'C during this time and for 2 hours after the addition of the initiator. 800 ml of water are then added, and a highly viscous solution which has a solids content of 11.0% and a pH of 6.6 is obtained. The K value of the copolymer is 172.
Hydrolysis 500 g of the aqueous solution, described above, of the copolymer of 64.1% by weight of N-vinylformamide and 35.9% by weight of sodium acrylate are initially taken in a stirred apparatus and are diluted by adding 250 g of water. 77.2 g of 38% strength hydrochloric acid are then added in the course of 20 minutes at room temperature. The reaction mixture is then heated to 70~C and stirred for 8 hours at this temperature. Thereafter, it is cooled to room temperature and 120 g of 10% strength aqueous sodium hydroxide solution are added. The pH of the mixture is then 1.5.
In order to stabilize the reaction mixture, 15 g of 0.5% strength aqueous sodium bisulfite solution are added. The degree of hydro-lysis of the polymerized N-vinylformamide is 95%. The reaction solution has a polymer content of 5.6%. The copolymer contains vinylamine hydrochloride units, vinylformamide units and acrylic acid units (hydrolyzed copolymer 2). The K value of the polymer is 126.
Example 1 A 0.5% strength stock suspension in water was prepared from 50%
of spruce sulfite pulp and 50% of beech sulfite pulp. The pH of the stock suspension was 7.0 and the Schopper-Riegler (SR) free-ness was 30~. The stock suspension was then divided into 5 equal parts, 4 of which were mixed with the additives stated under b) to e). The 5 stock suspensions were then processed to give sheets having-a basis weight of 80 g/ma in a Rapid-Kothen laboratory sheet former:
Composition of the stock suspensions:
a) The stock suspension contained no further additives.
b) 1%, based on the fibers, of an aqueous solution of a commer-cial neutral wet strength resin based on a reaction product of epichlorohydrin aid a polyamidoamine obtained from diethy-lenetriamine and adipic acid was added to the stock suspen-sion.
c) 1%, ba-sed on fiber, of an aqueous solution of a polyvinyl-amine hydrochloride according to US A 2 721 140 was added to the stock suspension.
d) 1%, based on fiber, of the hydrolyzed copolymer 1 was added to the stock suspension.
e) 1%, based on fiber, of the hydrolyzed copolymer 2 was added to the stock suspension.
The sheets a) to e) were produced from the paper stock suspen-sions described above. The whiteness, the dry breaking length and the wet breaking length of the sheets obtained were measured. The results are shown in Table 1.
Table 1 a) b) c) d) e) Comparison (According to the invention) Whiteness (% 77.973.5 73.4 73.1 74.0 ref lectance ) Dry breaking length 23542903 2927 3102 2895 (m) Wet breaking length (m) Unaged 104 908 978 1009 956 Edged 5 min at 110~C 106 1032 1005 1118 1040 Example 2 A 0.5% strength stock suspension in water was prepared from 50%
of spruce sulfite pulp and 50% of beech sulfite pulp. The pH of the stock suspension was 4.5 and the freeness was 30~SR. The stock suspension was then divided into 5 equal parts, of which the samples b) tc~_e) were each mixed with 1%, based on dry fiber, of the additives stated below. The following stock suspensions were processed:
a) The stock suspension described above contained no further additives.
b) An aqueous solution of a commercial wet strength resin based on a reaction product of urea and formaldehyde was added to the stock suspension.
c) ~ aqueous solution of a hydrolyzed copolymer of 70% of N vi-nylformamide and 30% of vinyl acetate was added to the stock suspension, the K value of the polymer being 100 and the r . 0050/43722 degree of hydrolysis of N vinylformamide and vinyl acetate being >90%.
d) The hydrolyzed copolymer 1 was added to the stock suspension.
e) The hydrolyzed copolymer 2 was added to the stock suspension.
The stock suspensions described above were processed on a Rapid-Kothen apparatus to give the sheets a) to e). The whiteness, dry breaking length and wet strength of the sheets obtained are shown in Table 2.
Table 2 a) b) c) d) e) Comparison (According to the invention) Whiteness (% 80.4 77.9 75.1 75.3 75.8 reflectance) Dry breaking length 3278 3817 3950 4551 4159 (m) Wet breaking length (m) Unaged 134 796 1024 1101 877 Aged 5 min at 130C 143 1031 1062 1196 998 Example 3 A 0.2% strength stock suspension in water was prepared from mixed waste paper. The pH of the suspension was 7 and the freeness was 67°SR. The stock suspension was divided into 10 equal parts. One sample of the stock suspension remained unchanged, while the additives stated below were added to the other 9 samples. The following samples were available:
a) The stock suspension described above contains no further additives.
b) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of a commercial neutral wet strength resin based on a reaction product of epichlorohydrin and a polyamidoamine obtained from diethylenetriamine and adipic acid was added to the stock suspension described above.
c) 0.2%, based on the solids, of the commercial neutral wet strength resin described under b) was added to the stock sus-pension described above.
d) 0.4%, based on the solids, of the commercial neutral wet strength resin described under b) was added to the stock sus-pension described above.
e) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension described above.
f) 0.2%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension described above.
g) 0.4%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension described above.
h) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension described above.
i) 0.2%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension described above.
j) 0.4%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension.
After the additive had been allowed to act for 5 minutes, the samples b) to j) were each drained in a laboratory sheet former with formation of sheets having a basis weight of 68 g/m2. In order to determine the ash content and hence obtain a measure of the retention, the sheets were incinerated in a muffle furnace at from 900 to 1-OOO~C and the residue on ignition was determined gravimetrically. The results obtained are shown in Table 3.
Table 3 Example % Ash in paper Addition in %
a) Comparative Example 5.1 0 b) Comparative Example 8.6 0.1 c) Comparative Example 9.0 0.2 d) Comparative Example 10.1 0.4 e) (According to the invention)10.2 0.1 f) (According to the invention)11.2 0.2 g) (According to the invention)11.6 0.4 . 0050/43722 h) (Accordi-ngto invention) 10.4 0.1 the i) (Accordingto invention) 11.1 0.2 the j) (Accordingto invention) 11.4 0.4 the Example 4 A 0.2% strength stock suspension in water was prepared from mixed waste paper. The pH of the stock suspension was 7 and the free-ness was 67°SR. The stock suspension was divided into 10 equal parts, 9 of which were mixed with the additives stated below:
a) This sample contained no additives.
b) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of a commercial neutral wet strength resin based on a reaction product of epichlorohydrin and a polyamidoamine obtained from diethylenetriamine and adipic acid was added to the stock suspension.
c) 0.25% of the commercial neutral wet strength resin described under b) was added to the suspension described above.
d) 0.4%, based on the solids, of the neutral wet strength resin described under b) was added to the stock suspension described above.
e) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension.
f) 0.25% of the hydrolyzed copolymer 2 was added to the suspen-sion.
g) 0.4%, based on the solids, of the hydrolyzed copolymer 2 was added to the suspension.
h) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension described above.
i) 0.25%, based on the solids, of the hydrolyzed copolymer 1 was added to the stock suspension.
~) 0~4%, based on the solids, of the hydrolyzed copolymer 1 was added to the suspension.
0050/43722 ~ 14 ~ 2 8 ~
After an action time of 5 minutes, the samples described above were drained on a Schopper-Riegler apparatus at room temperature.
The drainage time is shown in Table 4.
5 Table 4 Example Drainage time (s/700 Addition ml) in a) Comparative Example 89 0 b) Comparative Example 68 0.1 c) Comparative Example 60 0.25 d) Comparative Example 50 0.4 e) (According to the invention)57 0.1 15f) (According to the invention)21 0.25 g) (According to the invention)10 0.4 h) (According to the invention)46 0.1 i) (According to the invention)31 0.25 j) (According to the invention)21 0.4
of 6.2. The K value of the copolymer is 177.
Hydrolysis of the polymerized N vinylformamide of copolymer 1 500 g of the aqueous solution, described above, of a copolymer of 75.4% by weight of vinylformamide and 24.6% by weight of sodium acrylate, having a K value of 177, are initially taken in an apparatus equipped with a stirrer and are diluted with 250 g of water. The mixture is first stirred at room temperature, and 80.2 g of 38% strength hydrochloric acid are added in the course of 20 minutes. Thereafter, the reaction mixture is heated at 70°C
for 7 hours and is cooled to room temperature, and 120 g of a 10%
strength aqueous sodium hydroxide solution are added. The pH of the reaction mixture is then 1.5. In order to stabilize the reac-tion mixture, 15 g of 0.5% strength aqueous sodium bisulfite solution are added. The degree of hydrolysis of the polymerized N-vinylformamide is 93%. The solution has a polymer content of 5.8% by weight (hydrolyzed copolymer 1). The K value of the polymer is 135.
Copolymer 2 965.3 g of water, 1.34 g of a 75% strength aqueous phosphoric acid and 0.92 g of a 50% strength aqueous sodium hydroxide solu-tion are heated to 70°C in a stream of nitrogen in a polymeriza-tion apparatus. As soon as this temperature has been reached, a mixture of 100 g of water, 60 g of acrylic acid and 66.5 g of 50%
strength aqueous sodium hydroxide solution, separately from this 141.4 g of N vinylformamide and likewise separately from this a solution of 0.05 g of 2,2'-azobis(2~nethylpropionamidine) dihy-drochloride in 25 g of water are added uniformly, in each case in the course of 2 hours. After the end of the addition of initiator and monomers, a solution of 0.15 g of 2,2'-azobis(2~nethyl-propionamidine) dihydrochloride, dissolved in 73 g of water, is added in the course of 1 hour, the reaction mixture is kept at ~1~528~
i0 70'C during this time and for 2 hours after the addition of the initiator. 800 ml of water are then added, and a highly viscous solution which has a solids content of 11.0% and a pH of 6.6 is obtained. The K value of the copolymer is 172.
Hydrolysis 500 g of the aqueous solution, described above, of the copolymer of 64.1% by weight of N-vinylformamide and 35.9% by weight of sodium acrylate are initially taken in a stirred apparatus and are diluted by adding 250 g of water. 77.2 g of 38% strength hydrochloric acid are then added in the course of 20 minutes at room temperature. The reaction mixture is then heated to 70~C and stirred for 8 hours at this temperature. Thereafter, it is cooled to room temperature and 120 g of 10% strength aqueous sodium hydroxide solution are added. The pH of the mixture is then 1.5.
In order to stabilize the reaction mixture, 15 g of 0.5% strength aqueous sodium bisulfite solution are added. The degree of hydro-lysis of the polymerized N-vinylformamide is 95%. The reaction solution has a polymer content of 5.6%. The copolymer contains vinylamine hydrochloride units, vinylformamide units and acrylic acid units (hydrolyzed copolymer 2). The K value of the polymer is 126.
Example 1 A 0.5% strength stock suspension in water was prepared from 50%
of spruce sulfite pulp and 50% of beech sulfite pulp. The pH of the stock suspension was 7.0 and the Schopper-Riegler (SR) free-ness was 30~. The stock suspension was then divided into 5 equal parts, 4 of which were mixed with the additives stated under b) to e). The 5 stock suspensions were then processed to give sheets having-a basis weight of 80 g/ma in a Rapid-Kothen laboratory sheet former:
Composition of the stock suspensions:
a) The stock suspension contained no further additives.
b) 1%, based on the fibers, of an aqueous solution of a commer-cial neutral wet strength resin based on a reaction product of epichlorohydrin aid a polyamidoamine obtained from diethy-lenetriamine and adipic acid was added to the stock suspen-sion.
c) 1%, ba-sed on fiber, of an aqueous solution of a polyvinyl-amine hydrochloride according to US A 2 721 140 was added to the stock suspension.
d) 1%, based on fiber, of the hydrolyzed copolymer 1 was added to the stock suspension.
e) 1%, based on fiber, of the hydrolyzed copolymer 2 was added to the stock suspension.
The sheets a) to e) were produced from the paper stock suspen-sions described above. The whiteness, the dry breaking length and the wet breaking length of the sheets obtained were measured. The results are shown in Table 1.
Table 1 a) b) c) d) e) Comparison (According to the invention) Whiteness (% 77.973.5 73.4 73.1 74.0 ref lectance ) Dry breaking length 23542903 2927 3102 2895 (m) Wet breaking length (m) Unaged 104 908 978 1009 956 Edged 5 min at 110~C 106 1032 1005 1118 1040 Example 2 A 0.5% strength stock suspension in water was prepared from 50%
of spruce sulfite pulp and 50% of beech sulfite pulp. The pH of the stock suspension was 4.5 and the freeness was 30~SR. The stock suspension was then divided into 5 equal parts, of which the samples b) tc~_e) were each mixed with 1%, based on dry fiber, of the additives stated below. The following stock suspensions were processed:
a) The stock suspension described above contained no further additives.
b) An aqueous solution of a commercial wet strength resin based on a reaction product of urea and formaldehyde was added to the stock suspension.
c) ~ aqueous solution of a hydrolyzed copolymer of 70% of N vi-nylformamide and 30% of vinyl acetate was added to the stock suspension, the K value of the polymer being 100 and the r . 0050/43722 degree of hydrolysis of N vinylformamide and vinyl acetate being >90%.
d) The hydrolyzed copolymer 1 was added to the stock suspension.
e) The hydrolyzed copolymer 2 was added to the stock suspension.
The stock suspensions described above were processed on a Rapid-Kothen apparatus to give the sheets a) to e). The whiteness, dry breaking length and wet strength of the sheets obtained are shown in Table 2.
Table 2 a) b) c) d) e) Comparison (According to the invention) Whiteness (% 80.4 77.9 75.1 75.3 75.8 reflectance) Dry breaking length 3278 3817 3950 4551 4159 (m) Wet breaking length (m) Unaged 134 796 1024 1101 877 Aged 5 min at 130C 143 1031 1062 1196 998 Example 3 A 0.2% strength stock suspension in water was prepared from mixed waste paper. The pH of the suspension was 7 and the freeness was 67°SR. The stock suspension was divided into 10 equal parts. One sample of the stock suspension remained unchanged, while the additives stated below were added to the other 9 samples. The following samples were available:
a) The stock suspension described above contains no further additives.
b) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of a commercial neutral wet strength resin based on a reaction product of epichlorohydrin and a polyamidoamine obtained from diethylenetriamine and adipic acid was added to the stock suspension described above.
c) 0.2%, based on the solids, of the commercial neutral wet strength resin described under b) was added to the stock sus-pension described above.
d) 0.4%, based on the solids, of the commercial neutral wet strength resin described under b) was added to the stock sus-pension described above.
e) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension described above.
f) 0.2%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension described above.
g) 0.4%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension described above.
h) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension described above.
i) 0.2%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension described above.
j) 0.4%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension.
After the additive had been allowed to act for 5 minutes, the samples b) to j) were each drained in a laboratory sheet former with formation of sheets having a basis weight of 68 g/m2. In order to determine the ash content and hence obtain a measure of the retention, the sheets were incinerated in a muffle furnace at from 900 to 1-OOO~C and the residue on ignition was determined gravimetrically. The results obtained are shown in Table 3.
Table 3 Example % Ash in paper Addition in %
a) Comparative Example 5.1 0 b) Comparative Example 8.6 0.1 c) Comparative Example 9.0 0.2 d) Comparative Example 10.1 0.4 e) (According to the invention)10.2 0.1 f) (According to the invention)11.2 0.2 g) (According to the invention)11.6 0.4 . 0050/43722 h) (Accordi-ngto invention) 10.4 0.1 the i) (Accordingto invention) 11.1 0.2 the j) (Accordingto invention) 11.4 0.4 the Example 4 A 0.2% strength stock suspension in water was prepared from mixed waste paper. The pH of the stock suspension was 7 and the free-ness was 67°SR. The stock suspension was divided into 10 equal parts, 9 of which were mixed with the additives stated below:
a) This sample contained no additives.
b) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of a commercial neutral wet strength resin based on a reaction product of epichlorohydrin and a polyamidoamine obtained from diethylenetriamine and adipic acid was added to the stock suspension.
c) 0.25% of the commercial neutral wet strength resin described under b) was added to the suspension described above.
d) 0.4%, based on the solids, of the neutral wet strength resin described under b) was added to the stock suspension described above.
e) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 2 was added to the stock suspension.
f) 0.25% of the hydrolyzed copolymer 2 was added to the suspen-sion.
g) 0.4%, based on the solids, of the hydrolyzed copolymer 2 was added to the suspension.
h) 0.1%, based on the solids, of a 0.1% strength aqueous solu-tion of the hydrolyzed copolymer 1 was added to the stock suspension described above.
i) 0.25%, based on the solids, of the hydrolyzed copolymer 1 was added to the stock suspension.
~) 0~4%, based on the solids, of the hydrolyzed copolymer 1 was added to the suspension.
0050/43722 ~ 14 ~ 2 8 ~
After an action time of 5 minutes, the samples described above were drained on a Schopper-Riegler apparatus at room temperature.
The drainage time is shown in Table 4.
5 Table 4 Example Drainage time (s/700 Addition ml) in a) Comparative Example 89 0 b) Comparative Example 68 0.1 c) Comparative Example 60 0.25 d) Comparative Example 50 0.4 e) (According to the invention)57 0.1 15f) (According to the invention)21 0.25 g) (According to the invention)10 0.4 h) (According to the invention)46 0.1 i) (According to the invention)31 0.25 j) (According to the invention)21 0.4
Claims (11)
1. Use of a copolymer which is obtainable by copolymerization of a) from 5 to 99 mol% of N-vinylcarboxamides of the formula where R1 and R2 are each H or C1-C6-alkyl, b) from 95 to 1 mol% of monoethylenically unsaturated carboxylic acids of 3 to 8 carbon atoms or the alkali metal, alkaline earth metal, or ammonium salts thereof and, if required, c) up to 30 mol% of vinyl acetate, N-vinylpyrrolidone, N-vinylimidazole, or a mixture thereof and, if required, d) up to 2 mol% of compounds which have at least two ethylenically unsaturated nonconjugated double bonds in the molecule, and subsequent partial or complete elimination of the groups from the N-vinylcarboxamides polymerized in the copolymer, with formation of amino or ammonium groups, as an additive to paper stock for increasing the drainage rate and the retention in papermaking and the dry and wet strength of the paper.
2. Use as claimed in claim 1, wherein the copolymer is obtainable by copolymerization of a) from 30 to 95 mol% of N-vinylformamide, b) from 70 to 5 mol% of acrylic acid, methacrylic acid, or the alkali metal, alkaline earth metal, or ammonium salts thereof, and c) from 0 to 30 mol% of vinyl acetate, N-vinylpyrrolidone, N-vinylimidazole, or a mixture thereof and subsequent hydrolysis of from 10 to 100% of the vinylformamide units polymerized in the copolymer.
3. Use as claimed in claim 1 or 2, wherein the copolymer is used in an amount of from 0.1 to 5% by weight, based on dry fibers.
4. A process for the production of paper with high dry and wet strengths, wherein the drainage rate and the retention are increased, comprising adding in an amount of 0.01 to wt %, based on dry fibers, to paper stock containing no further additives, a copolymer having a K value of 30 to 300 obtained by copolymerization of a) 5 to 99 mol% of an N-vinylcarboxamide of the formula wherein R1 and R2 are H, b) 95 to 1 mol% of monoethylenically unsaturated carboxylic acids having 3 to 8 carbon atoms or the alkali metal, alkaline earth metal or ammonium salts thereof, c) 0 to 30 mol% of vinyl acetate, N-vinylpyrrolidone, N-vinylimidazole or a mixture thereof, and d) 0 to 2 mol% of copolymerizable compounds having at least two ethylenically unsaturated nonconjugated double bonds, and subsequent partial or complete elimination of the acyl groups from said N-vinylcarboxyamide polymerized in the copolymer, with formation of amino or ammonium groups.
5. The process of claim 4, wherein said copolymer is obtained by copolymerization of a) 30 to 95 mol% N-vinylformamide, b) 70 to 5 mol% of acrylic acid, methylacrylic acid or alkali metal, alkaline earth metal or ammonium salts thereof, and c) 0 to 30 mol% of vinyl acetate, N-vinylpyrrolidone, N-vinylimidazole or mixtures thereof, and subsequent elimination of 10 to 100% of formyl groups on said vinylformamide monomers polymerized in the copolymer.
6. The process of claim 4 or 5, wherein 0.1 to 2 wt % of said copolymer is added to said paper stock.
7. The process of claim 4, wherein said copolymer comprises 30 to 95 mol% of said N-vinylcarboxamide and 70 to 5 mol% of said monoethylenically unsaturated carboxylic acids.
8. The process of claim 4, wherein said copolymer is prepared by copolymerizing 1 to 20 mol% of vinyl acetate, N-vinylpyrrolidone, N-vinylimidazole or mixtures thereof.
9. The process of claim 4, wherein said copolymer is prepared by copolymerizing 0.01 to 1 mol% of said copolymerizable compound having at least two ethylenically unsaturated nonconjugated double bonds.
10. The process of any one of claims 4 to 9, wherein said partial or complete elimination of said acyl groups comprises elimination of 30 to 100% of said groups.
11. The process of claim 10, wherein said partial or complete elimination of said acyl groups is partial elimination of 60 to 95% of said groups.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4241117.3 | 1992-12-07 | ||
| DE4241117A DE4241117A1 (en) | 1992-12-07 | 1992-12-07 | Use of hydrolyzed copolymers of N-vinylcarboxamides and monoethylenically unsaturated carboxylic acids in papermaking |
| PCT/EP1993/003305 WO1994013882A1 (en) | 1992-12-07 | 1993-11-25 | Use of hydrolysed copolymers of n-vinyl carboxylic acid amides and monoethylenisally unsaturated carboxylic acids in the manufacture of paper |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2145286A1 CA2145286A1 (en) | 1994-06-23 |
| CA2145286C true CA2145286C (en) | 2005-03-29 |
Family
ID=6474569
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002145286A Expired - Fee Related CA2145286C (en) | 1992-12-07 | 1993-11-25 | Use of hydrolysed copolymers of n-vinyl carboxylic acid amides and monoethylenically unsaturated carboxylic acids in the manufacture of paper |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0672212B1 (en) |
| JP (1) | JPH08504239A (en) |
| AT (1) | ATE139279T1 (en) |
| AU (1) | AU672464B2 (en) |
| CA (1) | CA2145286C (en) |
| DE (2) | DE4241117A1 (en) |
| ES (1) | ES2088316T3 (en) |
| FI (1) | FI952739A (en) |
| WO (1) | WO1994013882A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220412008A1 (en) * | 2021-06-29 | 2022-12-29 | Solenis Technologies, L.P. | N-vinyllactam-containing polymers for papermaking |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4439149C2 (en) * | 1994-11-03 | 1997-07-31 | Thueringisches Inst Textil | Process for the preparation of a homogeneous cellulose solution |
| US5591799A (en) * | 1995-03-03 | 1997-01-07 | Air Products And Chemicals, Inc. | Aqueous emulsion materials containing copolymerized vinyl amide monomers and hydrolysis products thereof |
| DE19607674A1 (en) * | 1996-02-29 | 1997-09-04 | Basf Ag | Use of hydrolyzed polymers of N-vinylcarboxamides as an agent for increasing the dry strength of paper, cardboard and cardboard |
| DE10315363A1 (en) | 2003-04-03 | 2004-10-14 | Basf Ag | Aqueous slurries of finely divided fillers, process for their preparation and their use for the production of filler-containing papers |
| DE10334133A1 (en) | 2003-07-25 | 2005-02-24 | Basf Ag | Aqueous composition and its use for papermaking |
| DE102004056551A1 (en) | 2004-11-23 | 2006-05-24 | Basf Ag | Process for the production of paper, cardboard and cardboard with high dry strength |
| CN101405457B (en) * | 2006-03-16 | 2011-08-17 | 巴斯夫欧洲公司 | Method for producing paper, paperboard and cardboard having high dry strength |
| ES2378425T5 (en) | 2007-07-05 | 2017-05-16 | Omya International Ag. | Aqueous suspensions of finely divided fillers, process for their preparation and use for the manufacture of papers with high content in fillers and high dry strength |
| EP2304106B1 (en) * | 2008-06-24 | 2018-09-12 | Basf Se | Production of paper |
| US8926797B2 (en) * | 2009-06-16 | 2015-01-06 | Basf Se | Method for increasing the dry strength of paper, paperboard, and cardboard |
| MX2012006279A (en) * | 2009-12-18 | 2012-07-10 | Hercules Inc | Paper sizing composition. |
| US9562326B2 (en) * | 2013-03-14 | 2017-02-07 | Kemira Oyj | Compositions and methods of making paper products |
| WO2015144428A1 (en) | 2014-03-28 | 2015-10-01 | Basf Se | Method for producing corrugated cardboard |
| WO2016001016A1 (en) | 2014-07-03 | 2016-01-07 | Basf Se | Aqueous surface-coating agent for paper and paperboard |
| WO2016058730A1 (en) * | 2014-10-13 | 2016-04-21 | Basf Se | Solidifying composition for paper and cardboard |
| ES2948357T3 (en) | 2015-08-06 | 2023-09-11 | Solenis Technologies Cayman Lp | Procedure for making paper |
| US11680371B2 (en) | 2017-10-18 | 2023-06-20 | Solenis Technologies, L.P. | Method for producing multi-layer paper |
| WO2019076703A1 (en) * | 2017-10-18 | 2019-04-25 | Basf Se | Method for producing single-layer or multi-layer paper |
| KR20210061362A (en) * | 2018-09-14 | 2021-05-27 | 솔레니스 테크놀러지스 케이맨, 엘.피. | Polymer Hydrolysis Method |
| EP3850020A1 (en) * | 2018-09-14 | 2021-07-21 | Solenis Technologies Cayman, L.P. | Method for producing paper or cardboard |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1283748C (en) * | 1986-06-25 | 1991-04-30 | Takaharu Itagaki | Vinylamine copolymer, flocculating agent and paper strength increasingagent using the same, as well as process for producing the same |
| JP2913756B2 (en) * | 1990-04-25 | 1999-06-28 | 三菱化学株式会社 | How to size paper |
-
1992
- 1992-12-07 DE DE4241117A patent/DE4241117A1/en not_active Withdrawn
-
1993
- 1993-11-25 EP EP94901873A patent/EP0672212B1/en not_active Expired - Lifetime
- 1993-11-25 AU AU56274/94A patent/AU672464B2/en not_active Ceased
- 1993-11-25 JP JP6513717A patent/JPH08504239A/en active Pending
- 1993-11-25 AT AT94901873T patent/ATE139279T1/en not_active IP Right Cessation
- 1993-11-25 CA CA002145286A patent/CA2145286C/en not_active Expired - Fee Related
- 1993-11-25 ES ES94901873T patent/ES2088316T3/en not_active Expired - Lifetime
- 1993-11-25 WO PCT/EP1993/003305 patent/WO1994013882A1/en active IP Right Grant
- 1993-11-25 DE DE59302953T patent/DE59302953D1/en not_active Expired - Fee Related
-
1995
- 1995-06-05 FI FI952739A patent/FI952739A/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220412008A1 (en) * | 2021-06-29 | 2022-12-29 | Solenis Technologies, L.P. | N-vinyllactam-containing polymers for papermaking |
Also Published As
| Publication number | Publication date |
|---|---|
| AU672464B2 (en) | 1996-10-03 |
| WO1994013882A1 (en) | 1994-06-23 |
| EP0672212A1 (en) | 1995-09-20 |
| DE59302953D1 (en) | 1996-07-18 |
| FI952739A0 (en) | 1995-06-05 |
| ES2088316T3 (en) | 1996-08-01 |
| AU5627494A (en) | 1994-07-04 |
| CA2145286A1 (en) | 1994-06-23 |
| EP0672212B1 (en) | 1996-06-12 |
| JPH08504239A (en) | 1996-05-07 |
| FI952739A (en) | 1995-06-05 |
| ATE139279T1 (en) | 1996-06-15 |
| DE4241117A1 (en) | 1994-06-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2145286C (en) | Use of hydrolysed copolymers of n-vinyl carboxylic acid amides and monoethylenically unsaturated carboxylic acids in the manufacture of paper | |
| US5630907A (en) | Use of hydrolyzed copolymers of N-vinylcarboxamides and monoethylenically unsaturated carboxylic acids in papermaking | |
| KR100598663B1 (en) | Aqueous dispersions of water-soluble polymers of n-vinyl carboxylic acid amides, method for the production and use thereof | |
| CA1287945C (en) | Preparation of water-soluble copolymers containing vinylamine units, and their use as wet strength agents and dry strength agents for paper | |
| CA2726500C (en) | Production of paper | |
| USRE44936E1 (en) | Aldehyde-functionalized polymers | |
| US8349134B2 (en) | Method for producing high dry strength paper, paperboard or cardboard | |
| US5753759A (en) | Graft polymers containing N-vinyl units, their preparation and their use | |
| US8097126B2 (en) | Aqueous composition and use thereof for paper production | |
| CA2520895C (en) | Aqueous elutriations of fine-particled filling materials, methods for the production thereof and use thereof in the production of paper containing filling materials | |
| US9765483B2 (en) | Production of paper, card and board | |
| US6273998B1 (en) | Production of paper and paperboard | |
| AU715574B2 (en) | Hydrolyzed polymers of N-vinylcarboxamides as paper, paperboard and cardboard dry strength enhancers | |
| CA2216847C (en) | Water-soluble cationic copolymers and their use as flocculants and drainage retention aids | |
| US5662781A (en) | Elimination of nitrile impurities from polymers | |
| US5516852A (en) | Method of producing water-soluble cationic copolymers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |