CA2049059A1 - Cationic urea-formaldehyde condensates, preparation thereof, and use thereof in the paper industry - Google Patents
Cationic urea-formaldehyde condensates, preparation thereof, and use thereof in the paper industryInfo
- Publication number
- CA2049059A1 CA2049059A1 CA002049059A CA2049059A CA2049059A1 CA 2049059 A1 CA2049059 A1 CA 2049059A1 CA 002049059 A CA002049059 A CA 002049059A CA 2049059 A CA2049059 A CA 2049059A CA 2049059 A1 CA2049059 A1 CA 2049059A1
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- Prior art keywords
- urea
- formaldehyde
- stage
- cationic
- paper
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- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
- C08G12/04—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
- C08G12/10—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with acyclic compounds having the moiety X=C(—N<)2 in which X is O, S or —N
- C08G12/12—Ureas; Thioureas
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
- C08G12/04—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
- C08G12/10—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with acyclic compounds having the moiety X=C(—N<)2 in which X is O, S or —N
- C08G12/14—Dicyandiamides; Dicyandiamidines; Guanidines; Biguanidines; Biuret; Semicarbazides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
- C08G12/26—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds
- C08G12/34—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds and acyclic or carbocyclic compounds
- C08G12/36—Ureas; Thioureas
- C08G12/38—Ureas; Thioureas and melamines
-
- 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
- D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/47—Condensation polymers of aldehydes or ketones
- D21H17/49—Condensation polymers of aldehydes or ketones with compounds containing hydrogen bound to nitrogen
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Phenolic Resins Or Amino Resins (AREA)
- Paper (AREA)
Abstract
O.Z. 0050/40658 Abstract of the Disclosure: Cationic urea-formaldehyde condensates useful as strength enhancers in papermaking are obtainable by (a) reacting urea with at least one alkanolamine in a molar ratio of from 1:1 to 6:1 at from 130 to 180°C with elimination of ammonia, (b) methylola-ting the reaction product of stage (a) with formaldehyde in an aqueous medium at a basic pH, (c) condensing the methylolation product in an aqueous medium at pH 0-6 and terminating the condensation reaction by adjusting the pH
to 6.2-8 and optionally diluting the reaction mixture with water.
to 6.2-8 and optionally diluting the reaction mixture with water.
Description
2 0 ~ 9 0 ~ ~ o. z . 0050/40658 Cationic urea-formaldehyde_condensates preparation thereof and use thereof in ~he paper industry The present invention relates to cationic urea-formaldehyde condensates, to a process for pr~paring them, and to their use as strength enhancers in paper-making.
It is known that urea-formaldehyde condensation products are u~ed a~ wet strength enhancers in papermaking. Cationically modified urea-formaldehyde condensates which are preparable by condensing urea and formaldehyde in the presence of amines or polyamines are likewise used as wet strength enhancers in papermaking.
Compar~d with unmodified urea-formaldehyde condensates they show improved effectiveness. It is also pos~ible to use condensation products of melamine, urea and formaldehyde for enhancing the wet strength of paper.
EP-B-0 123 196 discloses a process for preparing water-soluble cationic urea-formaldehyde resins wherein urea and formaldehyde are condensed in a molar ratio of from 1:1.5 to 1:3 in the presence of polyamines by first (a) precondensing at pH 8-14, then acidifying and (b) condensing at pH 1-5 till the onset of gelling, (c) adding from 0.3 to 1.5 mol of formaldehyde per mole of urea used, (d) postcondensing and then neutralizing the resin solution. The polyamines used here per mole of urea in the end product comprise from 5 to 50 g of poly-ethyleneLmine containing from 20 to 15,000 ethyleneimine units in copolymerized form. The water-soluble cationic urea-formaldehyde resins thus obtainable are used as auxiliaries in papermaking for enhancing the dry and wet strength of paper. When paper webs which contain these resins as strength enhancers are dried, an undesirable release of formaldehyde is observed. The release of formaldehyde during the drying of paper finished with the urea-formaldehyde resins mentioned at the beginning as wet strength enhancers is, however, still greater by far than with the condensation products of EP-B-0 123 196.
2~90~
- 2 O.Z. 0050/40658 It is an object of the present invention to provide urea-formaldehyde condensates which, when used as wet strength enhancers for paper, do not release as much formaldehyde in the drying of the paper as the conden-sates based on urea and formaldehyde hitherto used for this purpose.
We have found that this object is achieved by cationic urea-formaldehyde condensates obtainable by a) reacting urea with at least one alkanolamine in a molar ratio of from 1:1 to 6:1 at from 130 to 180C
with elimination of ammonia, b) methylolating the reaction product of stage (a) with formaldehyde in an aqueous medium at a basic pH, c) condenslng the methylolation product in an aqueous medium at pH 0-6 with formation of a water-soluble cationic urea-formaldehyde condensate until the onset of gelling, and d) terminating the condensation reaction by adjusting the pH to 6.2-8 and optionally diluting the reaction mixture with water.
Modification of the cationic urea-formaldehyde condensates is achieved by carrying out the methylolation of stage (b) in the presence of from 0.5 to 5 mol, based on 1 mol of alkanolamine in stage (a), of urea, ethylene-urea, melamine, dicyandiamide or mixtures thereof. The cationic urea-formaldehyde condensates thus obtainable are used as strength enhancers in papermaking. When paper containing these condensates as strength enhancers is dried, less formaldehyde is released compared with known strength enhancers based on modified or unmodified urea-formaldehyde conden~ates.
The cationic urea-formaldehyde condensates of the present invention are prepared in a multistage reaction.
In stage (a) first urea is reacted with at least one alkanolamine in a molar ratio of from 1:1 to 6:1, pre-ferably from 3:1 to 4:1, at from 130 to 180C, preferably at from 140 to 160C, with elimination of ammonia. Any 9 ~ 5 ~9 - 3 - O.Z. 0050/40658 common alkanolamine can be used, eg. ethanolamine, diethanolamine, triethanolamine, diethylethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, di-n-propanolamine, triisopropanolamine, tri-n-propanol-5amine, aminoethoxyethanol, dimethylethanolamine, diethyl-ethanolamine (sic) and dLmethylaminoethoxyethanol. The alkanolamines can be used either alone or mixed with one another. Particular preference is given to the use of triethanolamine. The condensation reaction takes place 10with elimination of ammonia from the urea used, forming carbamts (sic). The reaction also produces an increase in the viscosity of the reaction mixture. The condensation is for example carried on until at 150C the reaction mixture has a viscosity of at least 300 mPas. Preferably, 15the reaction is carried on until the viscosities of the reaction mixtures, always determined at 150C, are from 300 to 3000 mPas. The reaction product thus obtainable can be isolated in the form of a powder or dissolved in water.
20Process stage (b) is a methylolation of the reaction products of stage (a). The methylolation is preferably carried out with formaldehyde in an aqueous solution at a basic pH. The concentration of the aqueous solution in terms of reaction products from (a) and 25formaldehyde is from 10 to 80, preferably from 40 to 60, % by weight. The pH of these aqueous solutions is ad~usted for the methylolation to values of from 7.5 to 14, preferably from B to 11. The methylolation itself is effected with the addition of formaldehyde, which can be 30passed into the solution of the reaction product (a) either in the form of an aqueous solution, as paraformal-dehyde or else as a gas. Preference is given to using formaldehyde in the industrially customary aqueous solution having a concentration of from 37 to ~0~ by 35 weight.
The methylolation can be carried out in the presence of modifiers, such as urea, ethyleneurea, 20~9~
It is known that urea-formaldehyde condensation products are u~ed a~ wet strength enhancers in papermaking. Cationically modified urea-formaldehyde condensates which are preparable by condensing urea and formaldehyde in the presence of amines or polyamines are likewise used as wet strength enhancers in papermaking.
Compar~d with unmodified urea-formaldehyde condensates they show improved effectiveness. It is also pos~ible to use condensation products of melamine, urea and formaldehyde for enhancing the wet strength of paper.
EP-B-0 123 196 discloses a process for preparing water-soluble cationic urea-formaldehyde resins wherein urea and formaldehyde are condensed in a molar ratio of from 1:1.5 to 1:3 in the presence of polyamines by first (a) precondensing at pH 8-14, then acidifying and (b) condensing at pH 1-5 till the onset of gelling, (c) adding from 0.3 to 1.5 mol of formaldehyde per mole of urea used, (d) postcondensing and then neutralizing the resin solution. The polyamines used here per mole of urea in the end product comprise from 5 to 50 g of poly-ethyleneLmine containing from 20 to 15,000 ethyleneimine units in copolymerized form. The water-soluble cationic urea-formaldehyde resins thus obtainable are used as auxiliaries in papermaking for enhancing the dry and wet strength of paper. When paper webs which contain these resins as strength enhancers are dried, an undesirable release of formaldehyde is observed. The release of formaldehyde during the drying of paper finished with the urea-formaldehyde resins mentioned at the beginning as wet strength enhancers is, however, still greater by far than with the condensation products of EP-B-0 123 196.
2~90~
- 2 O.Z. 0050/40658 It is an object of the present invention to provide urea-formaldehyde condensates which, when used as wet strength enhancers for paper, do not release as much formaldehyde in the drying of the paper as the conden-sates based on urea and formaldehyde hitherto used for this purpose.
We have found that this object is achieved by cationic urea-formaldehyde condensates obtainable by a) reacting urea with at least one alkanolamine in a molar ratio of from 1:1 to 6:1 at from 130 to 180C
with elimination of ammonia, b) methylolating the reaction product of stage (a) with formaldehyde in an aqueous medium at a basic pH, c) condenslng the methylolation product in an aqueous medium at pH 0-6 with formation of a water-soluble cationic urea-formaldehyde condensate until the onset of gelling, and d) terminating the condensation reaction by adjusting the pH to 6.2-8 and optionally diluting the reaction mixture with water.
Modification of the cationic urea-formaldehyde condensates is achieved by carrying out the methylolation of stage (b) in the presence of from 0.5 to 5 mol, based on 1 mol of alkanolamine in stage (a), of urea, ethylene-urea, melamine, dicyandiamide or mixtures thereof. The cationic urea-formaldehyde condensates thus obtainable are used as strength enhancers in papermaking. When paper containing these condensates as strength enhancers is dried, less formaldehyde is released compared with known strength enhancers based on modified or unmodified urea-formaldehyde conden~ates.
The cationic urea-formaldehyde condensates of the present invention are prepared in a multistage reaction.
In stage (a) first urea is reacted with at least one alkanolamine in a molar ratio of from 1:1 to 6:1, pre-ferably from 3:1 to 4:1, at from 130 to 180C, preferably at from 140 to 160C, with elimination of ammonia. Any 9 ~ 5 ~9 - 3 - O.Z. 0050/40658 common alkanolamine can be used, eg. ethanolamine, diethanolamine, triethanolamine, diethylethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, di-n-propanolamine, triisopropanolamine, tri-n-propanol-5amine, aminoethoxyethanol, dimethylethanolamine, diethyl-ethanolamine (sic) and dLmethylaminoethoxyethanol. The alkanolamines can be used either alone or mixed with one another. Particular preference is given to the use of triethanolamine. The condensation reaction takes place 10with elimination of ammonia from the urea used, forming carbamts (sic). The reaction also produces an increase in the viscosity of the reaction mixture. The condensation is for example carried on until at 150C the reaction mixture has a viscosity of at least 300 mPas. Preferably, 15the reaction is carried on until the viscosities of the reaction mixtures, always determined at 150C, are from 300 to 3000 mPas. The reaction product thus obtainable can be isolated in the form of a powder or dissolved in water.
20Process stage (b) is a methylolation of the reaction products of stage (a). The methylolation is preferably carried out with formaldehyde in an aqueous solution at a basic pH. The concentration of the aqueous solution in terms of reaction products from (a) and 25formaldehyde is from 10 to 80, preferably from 40 to 60, % by weight. The pH of these aqueous solutions is ad~usted for the methylolation to values of from 7.5 to 14, preferably from B to 11. The methylolation itself is effected with the addition of formaldehyde, which can be 30passed into the solution of the reaction product (a) either in the form of an aqueous solution, as paraformal-dehyde or else as a gas. Preference is given to using formaldehyde in the industrially customary aqueous solution having a concentration of from 37 to ~0~ by 35 weight.
The methylolation can be carried out in the presence of modifiers, such as urea, ethyleneurea, 20~9~
- 4 - O.Z. 0050/40658 melamine, dicyandiamide and/or propyleneurea. The modi-fiers can be added to the aqueous solution of the reac-tion product obtained in stage (a) in the form of an aqueous solution or else as a powder. The modifiers are used in an amount of from 0.5 to 5 mol, based on 1 mol of the alkanolamine incorporated as condensed units in stage (a). The methylolation in process stage (b3 is customarily carried out at from 50 to 90C. The methyl-olation, which may also be termed a precondensation, takes from about 10 minutes to 2 hours, depending on the temperature. It is followed by the condensation in process stage (c).
To condense the methylolated products of process stage (b), the pH of the aqueous solution is adjusted to 0-6, preferably l-S. This can be done not only with mineral acids but also with organic acids, for example sulfuric acid, phosphoric acid, hydrochloric acid, formic acid, acetic acid, propionic acid, p-toluenesulfonic acid, benzenesulfonic acid, amidosulfuric acid and chloroacetic acid. It is of course also possible to use mixtures of various acids. The condensation in process stage (c) is carried out at from 60 to 100C, preferably at from 70 to 90C. Water-soluble cationic urea-formal-dehyde condensates are formed. It is preferably carried on until gelling is evident from the fact that the stirrer vortex disappears, even at high speeds, and instead the reaction product climbs up the stirrer. The condensation reaction takes from 15 minutes to 3 hours, depending on the temperature and the pH, high tempera-tures producing short reaction times and high pH values producing long condensation times.
As soon as the methylolation products being condensed are observed to undergo gelling, the condensa-tion reaction is terminated in reaction stage (d) by ad~usting the pH to 6.2-8, preferably 6.5-7.5. To neutra-lize the reaction mixture to values within the stated pH
range, use is made for example of sodium hydroxide 2 8 ~ 9 ~
To condense the methylolated products of process stage (b), the pH of the aqueous solution is adjusted to 0-6, preferably l-S. This can be done not only with mineral acids but also with organic acids, for example sulfuric acid, phosphoric acid, hydrochloric acid, formic acid, acetic acid, propionic acid, p-toluenesulfonic acid, benzenesulfonic acid, amidosulfuric acid and chloroacetic acid. It is of course also possible to use mixtures of various acids. The condensation in process stage (c) is carried out at from 60 to 100C, preferably at from 70 to 90C. Water-soluble cationic urea-formal-dehyde condensates are formed. It is preferably carried on until gelling is evident from the fact that the stirrer vortex disappears, even at high speeds, and instead the reaction product climbs up the stirrer. The condensation reaction takes from 15 minutes to 3 hours, depending on the temperature and the pH, high tempera-tures producing short reaction times and high pH values producing long condensation times.
As soon as the methylolation products being condensed are observed to undergo gelling, the condensa-tion reaction is terminated in reaction stage (d) by ad~usting the pH to 6.2-8, preferably 6.5-7.5. To neutra-lize the reaction mixture to values within the stated pH
range, use is made for example of sodium hydroxide 2 8 ~ 9 ~
- 5 - O.Z. 0050/40658 solution, potassium hydroxide solution, ammonia, amines, sodium carbonate, potassium carbonate, sodium bicarbonate or mixtures of two or more bases. Preference is given to using sodium hydroxide solution. The reaction mixture may be diluted with water before the condensation is ter-minated or else not until after a base has been added for the purpose of ad~usting the pH. This produces aqueous solutions having a concentration of from 5 to 50% by weight in respect of cationic urea-formaldehyde conden-sates. Preferably, the concentration of the condensates is ad~usted in such a way that the aqueous solutions are from 8 to 40% strength by weight. It is of course also possible to isolate the cationic urea-formaldehyde resins from the aqueous solutions in solid form by evaporating the water aftex the conden~ation reaction has been terminated.
The cationic urea-formaldehyde condensates thus obtainable are preferably used in the form of the aqueous solution as strength enhancer in papermaking. This purpose requires amounts of from 0.1 to 10% by weight of the condensates, based on the dry paper fiber. The cationic urea-formaldehyde condensates of the present invention can be used in the making of any known paper, cardboard or paperboard grade, for example writing, printing and packaging papers. The papers can be made from a plurality of different fiber materials, for example from sulfite or sulfate pulp in the bleached or unbleached state, groundwood, waste paper, thermomechani-cal pulp (TMP) and chemothermomechanical pulp (CTMP).
The cationic condensates may either be added to the paper stock prior to sheet formation or be applied to the surface of a sheet of paper, for example in the size press. After drying, the papers obtained will in all cases have improved strength values. Preferably, the cationic urea-formaldehyde condensates are added to the paper stock suspension in amounts of from 0.5 to 5% by weight, based on dry paper stock. The pH of the 2~llg~
The cationic urea-formaldehyde condensates thus obtainable are preferably used in the form of the aqueous solution as strength enhancer in papermaking. This purpose requires amounts of from 0.1 to 10% by weight of the condensates, based on the dry paper fiber. The cationic urea-formaldehyde condensates of the present invention can be used in the making of any known paper, cardboard or paperboard grade, for example writing, printing and packaging papers. The papers can be made from a plurality of different fiber materials, for example from sulfite or sulfate pulp in the bleached or unbleached state, groundwood, waste paper, thermomechani-cal pulp (TMP) and chemothermomechanical pulp (CTMP).
The cationic condensates may either be added to the paper stock prior to sheet formation or be applied to the surface of a sheet of paper, for example in the size press. After drying, the papers obtained will in all cases have improved strength values. Preferably, the cationic urea-formaldehyde condensates are added to the paper stock suspension in amounts of from 0.5 to 5% by weight, based on dry paper stock. The pH of the 2~llg~
- 6 - o.z. 0050/40658 suspension is within the range from 4.0 to 10, preferably from 6.0 to 8.5. The cationic condensates can be used not only in the making of lightweight coating (LWC) paper but also for paperboard or cardboard. The basis weight i~
within the range from 30 to 200, preferably from 35 to 150, g/m2 in the case of paper, and may be up to 600 g/m2 in the case of cardboard.
In the examples which follow, parts and per-centages are by weight.
15 parts of triethanolamine and 27 parts of urea are heated with stirring under nitrogen to 160C and left at that temperature until 6.5 parts of ammonia have been eliminated. The reaction mixture is then cooled down to 100C, and 17 parts of water are added.
The aqueous solution is then admixed with 42 parts of 40~ strength aqueous formaldehyde solution and 10 parts of urea and methylolated at 60C for 30 minutes.
Then sufficient formic acid is added to bring the reac-tion mixture to pH 5.0, and the reaction mixture is heated to 80C and condensed at that temperature until the stirrer vortex originally present has disappeared.
100 parts of water are then added, followed by sufficient sodium hydroxide solution until the reaction mixture pH
is 7Ø An aqueous solution of a cationic urea formal-dehyde condensate with a solid~ content of about 30% is obtained. The aqueous solution of the condensate is infinitely thinnable with water.
Comparative Example 1 in accordance with EP-B-0 123 196 565 parts (7.5 mol) of formaldehyde in the form of a 40~ strength aqueous solution, 220 parts (3.7 mol) of urea and 190 part~ of water were mixed with S0 part~
of a 50% strength aqueous solution of a polyethyleneimine containing 35 copolymerized ethyleneimine units, and the mixture was heated to 70C with stirring. After the mixture had been stirred at that temperature for 30 minutes, it was adjusted to pH 4.3 with formic acid. At 2 ~ .3 - 7 - O.Z. 0050/~0658 that pH and 70C the reaction mixture was condensed until the onset of gelling was observed. The condensation time was 2 hours. Following this main condensation, a mixture of 151 parts (2.0 mol) of formaldehyde in the form of a 50% strength aqueous solution, 4 parts of ethylene-diamine, 30 parts of water and 50 parts of methanol was added, and the resulting mixture was adjusted to pH 5.8 with 20~ strength aqueous sodium carbonate solution. The reaction mixture was post-condensed at 70C for 1 hour and then adjusted to pH 6.2. An aqueous solution of a polyethyleneimine-modified urea-formaldehyde condensate having a solids content of about 35% was obtained.
Comparative resin 2 As directed in Example 1 of DE-C-2 241 713, a stirred vessel was charged with 3.2 mol of 25~ strength formaldehyde per mole of melamine and then with the melamine, and the contents were heated at a uniform rate to 70C in the course of 30 minutes, during which a clear solution formed at pH 6-7.
After stirring at that temperature for one hour, 6.8 mol of 22% strength formaldehyde were added with effective cooling. A temperature of 30C was reached after about 40 min. 0.09 mol of concentrated salt solu-tion and 0.25 mol of 89% phosphoric acid were added at that temperature, and the resin solution was diluted with 52 mol of water.
URe of the cationic condensate of Example 1 as strength enhancer for paper.
An experimental papermaking machine having an operating width of 65 cm was used to produce paper having a basis weight of 70 g/m2 from 50% bleached pine sulfite pulp and 50~ bleached beech sulfite pulp at a speed of 60 m/min. The pH of the stock suspension was ad~usted to 4.5 with 2~ aluminum sulfate (calculated on dry fiber) and sulfuric acid. The freeness was 30 Schopper-Riegler (SR). This model stock was used to test the 2 ~
within the range from 30 to 200, preferably from 35 to 150, g/m2 in the case of paper, and may be up to 600 g/m2 in the case of cardboard.
In the examples which follow, parts and per-centages are by weight.
15 parts of triethanolamine and 27 parts of urea are heated with stirring under nitrogen to 160C and left at that temperature until 6.5 parts of ammonia have been eliminated. The reaction mixture is then cooled down to 100C, and 17 parts of water are added.
The aqueous solution is then admixed with 42 parts of 40~ strength aqueous formaldehyde solution and 10 parts of urea and methylolated at 60C for 30 minutes.
Then sufficient formic acid is added to bring the reac-tion mixture to pH 5.0, and the reaction mixture is heated to 80C and condensed at that temperature until the stirrer vortex originally present has disappeared.
100 parts of water are then added, followed by sufficient sodium hydroxide solution until the reaction mixture pH
is 7Ø An aqueous solution of a cationic urea formal-dehyde condensate with a solid~ content of about 30% is obtained. The aqueous solution of the condensate is infinitely thinnable with water.
Comparative Example 1 in accordance with EP-B-0 123 196 565 parts (7.5 mol) of formaldehyde in the form of a 40~ strength aqueous solution, 220 parts (3.7 mol) of urea and 190 part~ of water were mixed with S0 part~
of a 50% strength aqueous solution of a polyethyleneimine containing 35 copolymerized ethyleneimine units, and the mixture was heated to 70C with stirring. After the mixture had been stirred at that temperature for 30 minutes, it was adjusted to pH 4.3 with formic acid. At 2 ~ .3 - 7 - O.Z. 0050/~0658 that pH and 70C the reaction mixture was condensed until the onset of gelling was observed. The condensation time was 2 hours. Following this main condensation, a mixture of 151 parts (2.0 mol) of formaldehyde in the form of a 50% strength aqueous solution, 4 parts of ethylene-diamine, 30 parts of water and 50 parts of methanol was added, and the resulting mixture was adjusted to pH 5.8 with 20~ strength aqueous sodium carbonate solution. The reaction mixture was post-condensed at 70C for 1 hour and then adjusted to pH 6.2. An aqueous solution of a polyethyleneimine-modified urea-formaldehyde condensate having a solids content of about 35% was obtained.
Comparative resin 2 As directed in Example 1 of DE-C-2 241 713, a stirred vessel was charged with 3.2 mol of 25~ strength formaldehyde per mole of melamine and then with the melamine, and the contents were heated at a uniform rate to 70C in the course of 30 minutes, during which a clear solution formed at pH 6-7.
After stirring at that temperature for one hour, 6.8 mol of 22% strength formaldehyde were added with effective cooling. A temperature of 30C was reached after about 40 min. 0.09 mol of concentrated salt solu-tion and 0.25 mol of 89% phosphoric acid were added at that temperature, and the resin solution was diluted with 52 mol of water.
URe of the cationic condensate of Example 1 as strength enhancer for paper.
An experimental papermaking machine having an operating width of 65 cm was used to produce paper having a basis weight of 70 g/m2 from 50% bleached pine sulfite pulp and 50~ bleached beech sulfite pulp at a speed of 60 m/min. The pH of the stock suspension was ad~usted to 4.5 with 2~ aluminum sulfate (calculated on dry fiber) and sulfuric acid. The freeness was 30 Schopper-Riegler (SR). This model stock was used to test the 2 ~
- 8 - O.Z. 0050/40658 effectiveness of the cationic condensate of Example 1 and of the comparative resins 1 and 2. In each case the strength enhancer was added to the thick stock.
The paper thus produced was subjected to measure-ments of the dry breaking length in accordance withDIN 53 112 Sheet 1 and of the wet breaking length in accordance with DIN 53 112 Sheet 2. The values reported in the Table are averages from the longitudinal and transverse direction of the paper relative to the paper machine.
Moreover, the amount of formaldehyde released by the paper web was determined in the first suction hood of the first dryer group(I) and the second dryer group (II) of the experimental paper machine.
First, the above-described model stock was used to produce a paper by dispensing with the addition of a wet strength enhancer. Then the cationic condensate of Example 1 and thereafter the comparative resins 1 and 2 were each used as strength enhancer. The quantities added and the results obtained therewith are shown in the ~able.
2~9~3~
The paper thus produced was subjected to measure-ments of the dry breaking length in accordance withDIN 53 112 Sheet 1 and of the wet breaking length in accordance with DIN 53 112 Sheet 2. The values reported in the Table are averages from the longitudinal and transverse direction of the paper relative to the paper machine.
Moreover, the amount of formaldehyde released by the paper web was determined in the first suction hood of the first dryer group(I) and the second dryer group (II) of the experimental paper machine.
First, the above-described model stock was used to produce a paper by dispensing with the addition of a wet strength enhancer. Then the cationic condensate of Example 1 and thereafter the comparative resins 1 and 2 were each used as strength enhancer. The quantities added and the results obtained therewith are shown in the ~able.
2~9~3~
9 - O . Z . O0S0/40658 E~ ~
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Claims (5)
We claim:
1. A cationic urea-formaldehyde condensate, obtainable by a) reacting urea with triethanolamine in a molar ratio of from 1:1 to 6:1 at from 130 to 180°C with elimination of ammonia, b) methylolating the reaction product of stage (a) with formaldehyde in an aqueous medium at a basic pH, c) condensing the methylolation product in an aqueous medium at pH 0-6 with formation of a water-soluble cationic urea-formaldehyde condensate until the onset of gelling, and d) terminating the condensation reaction by adjusting the pH to 6.2-8 and optionally diluting the reaction mixture with water.
2. A cationic urea-formaldehyde condensate as claimed in claim 1, wherein the methylolation of stage (b) is carried out in the additional presence of from 0.5 to 5 mol, based on 1 mol of alkanolamine in stage (a), of urea, ethyleneurea, melamine, dicyandiamide or a mixture thereof.
3. A process for preparing a cationic urea-formal-dehyde condensate as claimed in claim 1 or 2, which comprises (a) reacting urea with triethanolamine in a molar ratio of from 1:1 to 6:1 at from 130 to 180°C with elimination of ammonia, (b) methylolating the reaction product of stage (a) with formaldehyde in an aqueous medium at a basic pH in the presence or absence of from 0.5 to 5 mol, based on 1 mol of alkanolamine used in stage (a), of urea, ethyleneurea, melamine, dicyandiamide or a mixture thereof, (c) condensing the methylolation product in an aqueous REPLACEMENT PAGE
- 11 - O.Z. 0050/40658 medium at pH 0-6 with formation of a water-soluble cationic urea-formaldehyde condensate until the onset of gelling, and d) terminating the condensation reaction by adjusting the pH to 6.2-8 and optionally diluting the reaction mixture with water.
- 11 - O.Z. 0050/40658 medium at pH 0-6 with formation of a water-soluble cationic urea-formaldehyde condensate until the onset of gelling, and d) terminating the condensation reaction by adjusting the pH to 6.2-8 and optionally diluting the reaction mixture with water.
4. A process for enhancing the dry and wet strength of paper, wherein a cationic urea-formaldehyde condensate as claimed in claim 1 is added to the paper stock before sheet formation or applied to the surface of paper.
5. A process as claimed in claim 4, wherein the cationic urea-formaldehyde condensate as claimed in claim 1 is used in an amount of from 0.1 to 10% by weight, based on dry fiber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3909007.8 | 1989-03-18 | ||
| DE3909007A DE3909007A1 (en) | 1989-03-18 | 1989-03-18 | CATIONIC UREA FORMALDEHYDE CONDENSATES, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE IN THE PAPER INDUSTRY |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2049059A1 true CA2049059A1 (en) | 1990-09-19 |
Family
ID=6376710
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002049059A Abandoned CA2049059A1 (en) | 1989-03-18 | 1990-03-14 | Cationic urea-formaldehyde condensates, preparation thereof, and use thereof in the paper industry |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0463012B1 (en) |
| JP (1) | JPH04503824A (en) |
| CA (1) | CA2049059A1 (en) |
| DE (2) | DE3909007A1 (en) |
| ES (1) | ES2057541T3 (en) |
| PT (1) | PT93473A (en) |
| WO (1) | WO1990011308A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5110878A (en) * | 1991-05-14 | 1992-05-05 | E. I. Du Pont De Nemours And Company | Dry polyamide-epichlorohydrin resin power for strengthening wet paper |
| MY156194A (en) * | 2012-11-02 | 2016-01-20 | Kao Corp | Method for producing or method for storing liquid composition containing tetrahydro-4h-1,3,5-oxadiazin-4-one |
| MX2015008101A (en) | 2012-12-19 | 2016-04-25 | Georgia Pacific Chemicals Llc | Blends of polymers as wet strengthening agents for paper. |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2698787A (en) * | 1951-12-17 | 1955-01-04 | American Cyanamid Co | Urea-formaldehyde resins for wet strength paper and their use |
| US2917427A (en) * | 1955-12-14 | 1959-12-15 | Monsanto Chemicals | Thermosetting resins and high wet strength papers prepared therefrom |
| DE1595336A1 (en) * | 1966-08-09 | 1970-09-03 | Basf Ag | Process for the production of water-soluble cationic polycondensates |
| ZA793009B (en) * | 1978-06-24 | 1980-06-25 | British Plastics Ind Ltd | Modified melamine-formaldehyde condensation products |
| DE3313726A1 (en) * | 1983-04-15 | 1984-10-18 | Basf Ag, 6700 Ludwigshafen | METHOD FOR PRODUCING WATER-SOLUBLE CATIONIC UREA-FORMALDEHYDE RESINS AND THE USE THEREOF IN PAPER PRODUCTION |
-
1989
- 1989-03-18 DE DE3909007A patent/DE3909007A1/en not_active Withdrawn
-
1990
- 1990-03-14 DE DE9090904337T patent/DE59002039D1/en not_active Expired - Lifetime
- 1990-03-14 EP EP90904337A patent/EP0463012B1/en not_active Expired - Lifetime
- 1990-03-14 ES ES90904337T patent/ES2057541T3/en not_active Expired - Lifetime
- 1990-03-14 WO PCT/EP1990/000409 patent/WO1990011308A1/en active IP Right Grant
- 1990-03-14 CA CA002049059A patent/CA2049059A1/en not_active Abandoned
- 1990-03-14 JP JP2504222A patent/JPH04503824A/en active Pending
- 1990-03-16 PT PT93473A patent/PT93473A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| DE3909007A1 (en) | 1990-09-27 |
| PT93473A (en) | 1990-11-07 |
| WO1990011308A1 (en) | 1990-10-04 |
| EP0463012A1 (en) | 1992-01-02 |
| ES2057541T3 (en) | 1994-10-16 |
| JPH04503824A (en) | 1992-07-09 |
| DE59002039D1 (en) | 1993-08-26 |
| EP0463012B1 (en) | 1993-07-21 |
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