CA1047207A - Paper with synergistic dry strength additives and process therefor - Google Patents
Paper with synergistic dry strength additives and process thereforInfo
- Publication number
- CA1047207A CA1047207A CA229,200A CA229200A CA1047207A CA 1047207 A CA1047207 A CA 1047207A CA 229200 A CA229200 A CA 229200A CA 1047207 A CA1047207 A CA 1047207A
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- CA
- Canada
- Prior art keywords
- paper
- cationic polymer
- mol
- cationic
- polymer
- 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.)
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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
- 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
- D21H17/375—Poly(meth)acrylamide
-
- 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
Abstract
PAPER WITH SYNERGISTIC DRY STRENGTH ADDITIVES AND
PROCESS THEREFOR
Abstract of the Disclosure Paper of high dry strength is produced by adding to a solution of fibers from 0.1 to 2% of a cationic resin and from 0.1 to 2% of an anionic resin. Proportion of cationic to anionic resin is in the range of 99:1 to 50:50. The pre-ferred cationic resin is a condensation product of acetone, formaldehyde and polyalkylene polyamine which is prepared in presence of a catalytic amount of a strong inorganic acid and has a mol ratio of 1:3:0.5, respectively. The preferred anionic resin is a copolymer of acrylamide and maleic acid or its anhydride having a mol ratio of from 90:10 to 98:2.
PROCESS THEREFOR
Abstract of the Disclosure Paper of high dry strength is produced by adding to a solution of fibers from 0.1 to 2% of a cationic resin and from 0.1 to 2% of an anionic resin. Proportion of cationic to anionic resin is in the range of 99:1 to 50:50. The pre-ferred cationic resin is a condensation product of acetone, formaldehyde and polyalkylene polyamine which is prepared in presence of a catalytic amount of a strong inorganic acid and has a mol ratio of 1:3:0.5, respectively. The preferred anionic resin is a copolymer of acrylamide and maleic acid or its anhydride having a mol ratio of from 90:10 to 98:2.
Description
This invention relates to paper having high dry strength and negligible wet strength and to a process for its manufacture which is characterized by the use of a cationic resin in conjunction with an anionic resin. These resins com-bine to impart a synergistic effect in terms of dry strengthof the paper. The cationic~resin.is a condensation product of a polyamine, a ketone and an aldehyde which are condensed ;t reflux temperature in presence of a c~talytic amount of a strong inorganic acid. The anionic`resin is a copolymer of acryl-amide with maleic acid or its anhydride.
The use of the anionic and catinnic resins individuallyto impart high dry strength and negligible wet strength to paper is known. The combination of the two resins, however, was found to impart synergistic effect in terms of dry strength paper.
Dry strength of paper is defined as the strength of the cellulosic web in its normally dry condition. A resin which is used to improve dry strength of paper must fulfill a number of requirements: It should improve the dry strength by at least 10% over the normal dry strength of paper, it should confer a low degree of wet strength and~ it should not adversely affect the drainage rate of the cellulose web on the papermaking machine.
A dry strength additive finds uses in most grades of pa,per such as linerboard, packaging, towels and tissues. Dry strength additive is particularly useful in enabling paper manu-facturing industry to use weaker or recycled fibers. Recycling has been shown to have weakening effects on paper which can be counterba}anced by the use of a dry strength additive.
. . .
The use of the anionic and catinnic resins individuallyto impart high dry strength and negligible wet strength to paper is known. The combination of the two resins, however, was found to impart synergistic effect in terms of dry strength paper.
Dry strength of paper is defined as the strength of the cellulosic web in its normally dry condition. A resin which is used to improve dry strength of paper must fulfill a number of requirements: It should improve the dry strength by at least 10% over the normal dry strength of paper, it should confer a low degree of wet strength and~ it should not adversely affect the drainage rate of the cellulose web on the papermaking machine.
A dry strength additive finds uses in most grades of pa,per such as linerboard, packaging, towels and tissues. Dry strength additive is particularly useful in enabling paper manu-facturing industry to use weaker or recycled fibers. Recycling has been shown to have weakening effects on paper which can be counterba}anced by the use of a dry strength additive.
. . .
-2-Dry strength additives are especially useful in the manufacture of paper from recycled fibers. It is the need for recycling paper that a suitable dry strength resin should not confer high wet strength to the paper so that no additional equipment and processing is needed for the eventual repulping.
The art of making dry strength paper dates prior to 19~1 when the Azorlosa Canadian patent 477,265 issued. This patent discloses the use of an anionic copolymer of acrylamide or methacrylamide with acrylic or methacrylic acid together with alum. Pursuant to the Azorlosa's patent, paper of improved dry strength is manufactured by forming n aqueous suspension of cellulose paperma~ing fibers, adding thereto the anionic dry strength resin copolymer and alumr and sheeting the suspension.
The resulting paper possesses much better dry strength than normal paper and possesses virtually no wet strength so that it can be easily repulped.
- It is a disadvantage of the Azorlosa process, however !
that the paper is produced at the pH of 4.5 to 5. Paper pro-duced at pH of about 4.5 is significantly acid and undergoes acid tendering on aging. Moreover, papermaking systems opera-ting at this pH level impart a significant amount of corrosion to the apparatus under conditions of constan~ use and require strict control of pH. As a result, efforts have been made to discover means for increasing the operating pH range of paper-making systems producing dry strength paper of the type just described without sacri~icing the dry strength developed by the resin.
The close control of pH described in the prior art has been obviated by the invention described herein which allows manufacture of dry strength paper in a pH range of about 4 to 10~7;æO~
9, preferably 5.5 to 8, without weakening the resin to cellu-lose bond. This has been accomplished by the use of a cationic polymer of acetone, formaldehyde, polyalkylene polyamine with a small, catalytic amount of an inorganic acid and a copolymer of acrylamide with maleic acid or its anhydride.
The preferred reactants for the cationic resin herein include acetone, formaldehxde, diethylene triamine and hydro- --chloric acid. Mol ratio of acetone/fo~maldehyde/diethylene triamine can ~ary widely. Using acetone as a basis of 1 mol, amount of ~ormaldehyde can vary from 1.8 to 4 mols although
The art of making dry strength paper dates prior to 19~1 when the Azorlosa Canadian patent 477,265 issued. This patent discloses the use of an anionic copolymer of acrylamide or methacrylamide with acrylic or methacrylic acid together with alum. Pursuant to the Azorlosa's patent, paper of improved dry strength is manufactured by forming n aqueous suspension of cellulose paperma~ing fibers, adding thereto the anionic dry strength resin copolymer and alumr and sheeting the suspension.
The resulting paper possesses much better dry strength than normal paper and possesses virtually no wet strength so that it can be easily repulped.
- It is a disadvantage of the Azorlosa process, however !
that the paper is produced at the pH of 4.5 to 5. Paper pro-duced at pH of about 4.5 is significantly acid and undergoes acid tendering on aging. Moreover, papermaking systems opera-ting at this pH level impart a significant amount of corrosion to the apparatus under conditions of constan~ use and require strict control of pH. As a result, efforts have been made to discover means for increasing the operating pH range of paper-making systems producing dry strength paper of the type just described without sacri~icing the dry strength developed by the resin.
The close control of pH described in the prior art has been obviated by the invention described herein which allows manufacture of dry strength paper in a pH range of about 4 to 10~7;æO~
9, preferably 5.5 to 8, without weakening the resin to cellu-lose bond. This has been accomplished by the use of a cationic polymer of acetone, formaldehyde, polyalkylene polyamine with a small, catalytic amount of an inorganic acid and a copolymer of acrylamide with maleic acid or its anhydride.
The preferred reactants for the cationic resin herein include acetone, formaldehxde, diethylene triamine and hydro- --chloric acid. Mol ratio of acetone/fo~maldehyde/diethylene triamine can ~ary widely. Using acetone as a basis of 1 mol, amount of ~ormaldehyde can vary from 1.8 to 4 mols although
3 mols of formaldehyde to 1 mol of acetone is preferred. The amine can vary from 0.1 to 1 mol per mol of acetone, the pre-ferred amount being about 0.5 mol. Amount of the acid can vary from a negligible amount to 0.3 mol per each mol of ace-tone, although 0.05 mol is preferred. Within these permiss-ible ranges, an increase in the mol ratio of formaldehyde to acetone generally increases the wet and dry strength properties while a decrease in amount of amine, favors the dry strength property. The choice of the mol ratios depends on the desired degree of dry strength improvement and the acceptable level of wet strength for a specific grade of paper.
In~ addition to acetone, other suitable ketones include such acetone homologs -~as methyl ethyl ketone, methyl n-propyl ketone, hexanone-2, hexanone-3, chloroacetone, and bromoacetone.
Suitable ketones are unsubstituted and contain from 3 to about 8 carbon atoms per molecule with at least one reactive hydrogen atom at the alpha carbon position.
Other suitable aldehydes in addition to formaldehyde include acetaldehyde, propionaldehyde, n-butyraldehyde, iso-1047~ 7 RI 1651 butyraldehyde and n-valeraldehyde. Suitable aldehydes contain from 1 to about 5 carbon atoms per molecule.
Hydrochloric acid can be replaced by other strong in-orglanic acids such as hydrobromic, sulfuric and nitric.
Suitable polyamines in addition to the preferred di-ethylene triamine include alkylene diaminss such as ethylene diamine and propylene diam~ine; and polyalkylene polyamines con- -taining from 2 to 3 carbon atoms in tn~ alkylene moiety and from 2 to 6 amine groups, preferably from 2 to 5 amine groups.
Examples of suitable polyalkylene polyamines include tetra-ethylene pentamine, trieth~lene tetramine, diethylene triamine and a commercial product of Union Carbide sold as mixed amines PM-1953 which is a mixture of about 1/3 mol fraction of di-ethylene triamine and about 2/3 mol fraction of triethylene tetramine. The polyamines ~hou'd contain a total of 2 to 10 carbon atoms, preferably 4 to 8, and should have at least 2 re-active hydrogens which can participate in the reaction with a ketone and an aldehyde.
The reaction for preparing the cationic resin is carried out at reflux temperature of about 95C although temperatures in the range of 60 to 110C are suitable to a degree. The reactants are mixed with sufficient water to yield a condensate of about 20% solids concentration. The pH of the reaction mix-tures can be acid or alkaline but preferably, it should be above 7, as for instance 8 to 10. The reaction is carried out until the polymer reaches at least 10 cps Brookfield viscosity of a 20% solids solution measured at the refluxing temperature of about 95C with LVF #2 spindle at 60 rpm and as close to the gel point as possible. The preferred degree of condensation is represented by Brookfield viscosity of 40 to 60 cps measured at the same conditions. Generally speaking, the reaction can be carried out until the reaction mixture reaches gelation as evidenced by a rapid increase in Brookfield viscosity - --5-- o .
10~7207 as measured at 95C by LVF #2 spindle at 60 rpm.
The cationic resin is prepared by charging the follow-ing to a reactor with agitation and cooling:
(a) polyamine (b) water ~c) inorganic acid , (d) ketone, and (e) aldehyde Aldehyde, such as 50% aqueous solution of formaldehyde, is added to the reactor with cooling at s~ch a rate that the temperature is not allowed to exceed 40 C. Agitation of the mixture is continued at about 40 C for about one half hour and then the mixture is heated to reflux and maintained at reflux for about 2 hours. After this period of time, Brookfield LV~
~2/60 viscosity of the reaction product is measured every 15 minutes until 30 cps is reached and then it is measured every 5 minutes until 50 cps is reached. Water is added in order to terminate condensation at this point. The condensate is mixed for about one half hour without cooling and then cooled to room temperature.
The,preferred cationic resin has the following physical properties:
solids 12% + 1 Brookfield Viscosity (LVF #2/10/25C) 20 cps + 5 pH 8.5 + 0.5 The anionic resin is a copolymer of acrylamide and maleic acid or maleic anhydride or a copolymer of acrylamide or methacrylamide with acrylic or methacrylic acids. The preferred acrylamide/maleic acid copolymer has a mol ratio of I' 1047;~0'7 from 90:10to 98:2, preferably 95:5, and has a molecular weight of from 0.5 to 6.0 dl/g, preferably from 1.0 to 1.5 dl/g, as represented by intrinsic viscosity measured in 0.1 N NaCl solution at 25 C. This copolymer is polymerized in aqueous solution using common initiator such as potassium persulfate.
The acrylamide/maleic acid ~opolymer has the following pre- -ferred physical properties.
solids 20% + 1 Brookfield Viscosity (LVF#4/30/90C) 400 to 800 cps pH 6 to 7 The other anionic copolymer is disclosed in the Canadian patent 477,265 issued to Azorlosa on September 25, 1951. This product is a copolymer of acrylamide or metha-cryl~mide with acrylic or methac ylic acids wherein the re-spective mol ratio is from 99:1 to 75:25%, preferably from 95:5 to 88:12%. Suitable specific viscosity (Ubbelohde) of this copolymer is between 0.2 and 100, preferably from 1 to 10, measured in a 0.5~ aqueous solution.
The cationic resin is added in excess of the anionic resin for synergistic effect, the weight ratio being from 99:1 to 50:50, preferably from 90:10 to 70:30. Generally, however, total amount of the resin used is from 0.05 to 3%, preferably from 0.1 to 2%, of the cationic resin and from 0.05 to 3%, preferably from 0.1 to 2%of the anionic resin, based on the dry weight of the cellulosic fibers.
In accordance with the instant invention, dry strength paper can be manuactured under normal papermaking conditions by the use of a cationic acetone/formaldehyde/polyamine conden-sate in conjunction with the anionic resins described above.
~\ ~
Synergism of these two resins occurs in the range specified above. The best composition should be found empirically for each papermaking system. Experience shows that a ratio larger than 1 for cationic resin to anionic polymer is preferred in order to achieve more pronounced effect and better economic values. In others words, in a very specific sense, this in-vention ~elates to the use of an anionic acrylamide/maleic acid or acrylamide/acrylic~acid copolymer to improve the per-formance of a specific cationic dry strength resin making use ~X ,, of unexpected synergism.
The resins described above are used in aqueous solu-tions under normal papermaking conditions in amounts required by the papermkaing industry to achieve its objectives. Generally, the use of 0.1 to 5~, preferably from 0.2 to 2% of the dry resin on the basis of dry pulp will provide sufficient improvement in bursting and tensile strengths. The resins are preferably added at points in the paper machine where all the cleaning and refining processes have been complete, i.e., refined stock chest, head box, fan pump, machine chest, etc. The cationic 20 resin is preferably added after addition of the anionic resin and the cationic resin is preferably added at a point as close to the wire as possible.~ The resin can improve dry strength of furnishes when the pulp is maintained in the pH range of 4 to 9, depending on the acceptable degree of wet strength. For those desiring a lower degree of wet strength, pH of the pulp should be in escess of 5.5. The resin can confer dry strength to paper and improve drainage of stock on the wire preferably at pH of above 5.5 to about 8. Sufficient dry strength improvement can be achieved under normal papermaking conditions without post heat curing.
104720'7 The resins described above can be used with all stan-dard papermaking furnishes, including recycled papers. The utility of this invention is not limited to the particular type of paper pulp used; and, accordingly, this invention may be ut.'.lized with the various types of kraft, soda, sulfite pulp, ground wood, and the like, as well as with other chemical and semichemical paper pulps. By the same token, the invention may be utilized with various types of paper products such as paper, linerboard, molded pulp products, and the like. In all instances, the product produced by this invention is character-ized by having an increased dry strength and other improved pro-perties.
The papermaking process for utilizing the resins des-cribed herein includes the addition of dilute aqueous solutions of the resins at-a suitable point prior to such formation. In normal papermaking procedures, the paper stock is beaten to a Canadian Standard Freeness of 200 to 650 ml and consistency of the aqueous suspension of the cellulosic fibers can vary up to 10~; however, the preferred range is 0.1 to 5%.
20 . While the cationic resin is preferably added after the anionic resin, minor variation is permissible. For example, in paper mills constructed with a partially closed system, the recycled white water may contain certain amount of cationic and anionic resin and therefore, in practice, the preferred order of addition would.have altered to some extent. Both of the resins are added after all the refin.ing of pulp has been completed.
Several examples are presented below which illustrate preparation of the cationic and the anionic resins and which substantiate the syaergistic performance of the resins when r ~
. RI 16Sl, used in combination.
:.
Example I - Preparation of Cationic Res~n To a three necked flask equipped with a thermometer, a mechanical stirring device, sampling tube and a condenser, the following were added and mixed:
.~ .water 237.6 grams -concentrated hydrochlori.- aci~ 2.6 grams mixed amine 27.6 grams ~ acetone. 29.6 grams .formaldehyde 90.0 grams The mixed amine is a commercial product supplied by Union Carbide as Mixed Amine PM-1953 which contains approxi-mately 1/3 mol fraction of diethylene triamine and 2/3 mol fraction of triethylene tetramine. Formaldehyde was added in 50~ aqueous solution. The solution was heated gradually to refluxing at about 92 C. The reaction w~s stopped by adding 387.4 grams of water when it reached a Brookfield viscosity of 60 cps, LVF spindle ~2 at 60 rpm and 92~ C. The final product had the following properties:
solids 9.4%
Brookfield Viscosity (LVF$2/60/25C) 14.0 cps ~- p~ 9.0 . .
Example II - Preparation of Anionic Resin To a pilot plant kettle equipped with mechanical agi-tation device, feeding pumps, and temperature control, the ~ollowing materials were added and allowed to react:
Il) water 58.7 kg ~2) Sequestrene* No. 22 0.01 ~g (3) premix (A) * Sequestrene is a trademark for a series of complexing agents and metal complexes consisting of ethylenediamine-tetracetic acid and salts.
, 1047~7 RI 1651 (a) water 31.8 kg (b) acrylamide 29.4 kg (c) water 13.0 kg (d) maleic anhydride ~ 2.15 kg (e) NaOH (26 Be) 1.20 kg
In~ addition to acetone, other suitable ketones include such acetone homologs -~as methyl ethyl ketone, methyl n-propyl ketone, hexanone-2, hexanone-3, chloroacetone, and bromoacetone.
Suitable ketones are unsubstituted and contain from 3 to about 8 carbon atoms per molecule with at least one reactive hydrogen atom at the alpha carbon position.
Other suitable aldehydes in addition to formaldehyde include acetaldehyde, propionaldehyde, n-butyraldehyde, iso-1047~ 7 RI 1651 butyraldehyde and n-valeraldehyde. Suitable aldehydes contain from 1 to about 5 carbon atoms per molecule.
Hydrochloric acid can be replaced by other strong in-orglanic acids such as hydrobromic, sulfuric and nitric.
Suitable polyamines in addition to the preferred di-ethylene triamine include alkylene diaminss such as ethylene diamine and propylene diam~ine; and polyalkylene polyamines con- -taining from 2 to 3 carbon atoms in tn~ alkylene moiety and from 2 to 6 amine groups, preferably from 2 to 5 amine groups.
Examples of suitable polyalkylene polyamines include tetra-ethylene pentamine, trieth~lene tetramine, diethylene triamine and a commercial product of Union Carbide sold as mixed amines PM-1953 which is a mixture of about 1/3 mol fraction of di-ethylene triamine and about 2/3 mol fraction of triethylene tetramine. The polyamines ~hou'd contain a total of 2 to 10 carbon atoms, preferably 4 to 8, and should have at least 2 re-active hydrogens which can participate in the reaction with a ketone and an aldehyde.
The reaction for preparing the cationic resin is carried out at reflux temperature of about 95C although temperatures in the range of 60 to 110C are suitable to a degree. The reactants are mixed with sufficient water to yield a condensate of about 20% solids concentration. The pH of the reaction mix-tures can be acid or alkaline but preferably, it should be above 7, as for instance 8 to 10. The reaction is carried out until the polymer reaches at least 10 cps Brookfield viscosity of a 20% solids solution measured at the refluxing temperature of about 95C with LVF #2 spindle at 60 rpm and as close to the gel point as possible. The preferred degree of condensation is represented by Brookfield viscosity of 40 to 60 cps measured at the same conditions. Generally speaking, the reaction can be carried out until the reaction mixture reaches gelation as evidenced by a rapid increase in Brookfield viscosity - --5-- o .
10~7207 as measured at 95C by LVF #2 spindle at 60 rpm.
The cationic resin is prepared by charging the follow-ing to a reactor with agitation and cooling:
(a) polyamine (b) water ~c) inorganic acid , (d) ketone, and (e) aldehyde Aldehyde, such as 50% aqueous solution of formaldehyde, is added to the reactor with cooling at s~ch a rate that the temperature is not allowed to exceed 40 C. Agitation of the mixture is continued at about 40 C for about one half hour and then the mixture is heated to reflux and maintained at reflux for about 2 hours. After this period of time, Brookfield LV~
~2/60 viscosity of the reaction product is measured every 15 minutes until 30 cps is reached and then it is measured every 5 minutes until 50 cps is reached. Water is added in order to terminate condensation at this point. The condensate is mixed for about one half hour without cooling and then cooled to room temperature.
The,preferred cationic resin has the following physical properties:
solids 12% + 1 Brookfield Viscosity (LVF #2/10/25C) 20 cps + 5 pH 8.5 + 0.5 The anionic resin is a copolymer of acrylamide and maleic acid or maleic anhydride or a copolymer of acrylamide or methacrylamide with acrylic or methacrylic acids. The preferred acrylamide/maleic acid copolymer has a mol ratio of I' 1047;~0'7 from 90:10to 98:2, preferably 95:5, and has a molecular weight of from 0.5 to 6.0 dl/g, preferably from 1.0 to 1.5 dl/g, as represented by intrinsic viscosity measured in 0.1 N NaCl solution at 25 C. This copolymer is polymerized in aqueous solution using common initiator such as potassium persulfate.
The acrylamide/maleic acid ~opolymer has the following pre- -ferred physical properties.
solids 20% + 1 Brookfield Viscosity (LVF#4/30/90C) 400 to 800 cps pH 6 to 7 The other anionic copolymer is disclosed in the Canadian patent 477,265 issued to Azorlosa on September 25, 1951. This product is a copolymer of acrylamide or metha-cryl~mide with acrylic or methac ylic acids wherein the re-spective mol ratio is from 99:1 to 75:25%, preferably from 95:5 to 88:12%. Suitable specific viscosity (Ubbelohde) of this copolymer is between 0.2 and 100, preferably from 1 to 10, measured in a 0.5~ aqueous solution.
The cationic resin is added in excess of the anionic resin for synergistic effect, the weight ratio being from 99:1 to 50:50, preferably from 90:10 to 70:30. Generally, however, total amount of the resin used is from 0.05 to 3%, preferably from 0.1 to 2%, of the cationic resin and from 0.05 to 3%, preferably from 0.1 to 2%of the anionic resin, based on the dry weight of the cellulosic fibers.
In accordance with the instant invention, dry strength paper can be manuactured under normal papermaking conditions by the use of a cationic acetone/formaldehyde/polyamine conden-sate in conjunction with the anionic resins described above.
~\ ~
Synergism of these two resins occurs in the range specified above. The best composition should be found empirically for each papermaking system. Experience shows that a ratio larger than 1 for cationic resin to anionic polymer is preferred in order to achieve more pronounced effect and better economic values. In others words, in a very specific sense, this in-vention ~elates to the use of an anionic acrylamide/maleic acid or acrylamide/acrylic~acid copolymer to improve the per-formance of a specific cationic dry strength resin making use ~X ,, of unexpected synergism.
The resins described above are used in aqueous solu-tions under normal papermaking conditions in amounts required by the papermkaing industry to achieve its objectives. Generally, the use of 0.1 to 5~, preferably from 0.2 to 2% of the dry resin on the basis of dry pulp will provide sufficient improvement in bursting and tensile strengths. The resins are preferably added at points in the paper machine where all the cleaning and refining processes have been complete, i.e., refined stock chest, head box, fan pump, machine chest, etc. The cationic 20 resin is preferably added after addition of the anionic resin and the cationic resin is preferably added at a point as close to the wire as possible.~ The resin can improve dry strength of furnishes when the pulp is maintained in the pH range of 4 to 9, depending on the acceptable degree of wet strength. For those desiring a lower degree of wet strength, pH of the pulp should be in escess of 5.5. The resin can confer dry strength to paper and improve drainage of stock on the wire preferably at pH of above 5.5 to about 8. Sufficient dry strength improvement can be achieved under normal papermaking conditions without post heat curing.
104720'7 The resins described above can be used with all stan-dard papermaking furnishes, including recycled papers. The utility of this invention is not limited to the particular type of paper pulp used; and, accordingly, this invention may be ut.'.lized with the various types of kraft, soda, sulfite pulp, ground wood, and the like, as well as with other chemical and semichemical paper pulps. By the same token, the invention may be utilized with various types of paper products such as paper, linerboard, molded pulp products, and the like. In all instances, the product produced by this invention is character-ized by having an increased dry strength and other improved pro-perties.
The papermaking process for utilizing the resins des-cribed herein includes the addition of dilute aqueous solutions of the resins at-a suitable point prior to such formation. In normal papermaking procedures, the paper stock is beaten to a Canadian Standard Freeness of 200 to 650 ml and consistency of the aqueous suspension of the cellulosic fibers can vary up to 10~; however, the preferred range is 0.1 to 5%.
20 . While the cationic resin is preferably added after the anionic resin, minor variation is permissible. For example, in paper mills constructed with a partially closed system, the recycled white water may contain certain amount of cationic and anionic resin and therefore, in practice, the preferred order of addition would.have altered to some extent. Both of the resins are added after all the refin.ing of pulp has been completed.
Several examples are presented below which illustrate preparation of the cationic and the anionic resins and which substantiate the syaergistic performance of the resins when r ~
. RI 16Sl, used in combination.
:.
Example I - Preparation of Cationic Res~n To a three necked flask equipped with a thermometer, a mechanical stirring device, sampling tube and a condenser, the following were added and mixed:
.~ .water 237.6 grams -concentrated hydrochlori.- aci~ 2.6 grams mixed amine 27.6 grams ~ acetone. 29.6 grams .formaldehyde 90.0 grams The mixed amine is a commercial product supplied by Union Carbide as Mixed Amine PM-1953 which contains approxi-mately 1/3 mol fraction of diethylene triamine and 2/3 mol fraction of triethylene tetramine. Formaldehyde was added in 50~ aqueous solution. The solution was heated gradually to refluxing at about 92 C. The reaction w~s stopped by adding 387.4 grams of water when it reached a Brookfield viscosity of 60 cps, LVF spindle ~2 at 60 rpm and 92~ C. The final product had the following properties:
solids 9.4%
Brookfield Viscosity (LVF$2/60/25C) 14.0 cps ~- p~ 9.0 . .
Example II - Preparation of Anionic Resin To a pilot plant kettle equipped with mechanical agi-tation device, feeding pumps, and temperature control, the ~ollowing materials were added and allowed to react:
Il) water 58.7 kg ~2) Sequestrene* No. 22 0.01 ~g (3) premix (A) * Sequestrene is a trademark for a series of complexing agents and metal complexes consisting of ethylenediamine-tetracetic acid and salts.
, 1047~7 RI 1651 (a) water 31.8 kg (b) acrylamide 29.4 kg (c) water 13.0 kg (d) maleic anhydride ~ 2.15 kg (e) NaOH (26 Be) 1.20 kg
(4) premix (B) (a) water 11.3 kg (b) potassium persulfate 95.3 gr
(5) premix (C) (a) water 7.6 gr (b) potassium persulfate 145.0 gr
(6) premix (D) (a) water 2.5 kg (b) sodium bisulfite 0.9 gr After (1) and (2) were added and heated to about 100 C, (3) and (4) were fed into the reactor by the use of the feeding pump at such a rate that the additions of the two premixes were completed at the same time. Then (5) and (6~ were added. The reaction was allowed to continue for 4 hours after the start . of the feeding process. The product had the following properties:
solids 20.0%
Brookfield Viscosity (LVF #4/60/25C) 5,000 cps pH 5.2 Example III - Evaluation of Resins Effect of the additives on the strength of paper was evaluated by adding various amounts of the cationic and the anionic polymers prepared in accordance with Examples I and II, respectively. These polymers were added separately, and in con-junction with each other.
~047207 A refined unbleached kraft f~rnish from recycled kraft boxes was obtained from the stock chest of the paper machine of a local paper mill. The consistency was 3.5~, Cana~ian Standard Freeness was 426 ml, and the pH was 7Ø
This stock was diluted to a consistency of 0.25%.
To one liter aliquots of this stock slurry, various amounts of polymer samples prepared in Examples I and II
were added such that the'percentages of resin based on dry pulp were as shown in Table l.
This slurry was erptied into a Williams Sheet Mold containing sufficient water for the total solution to reach a standard volume. The water was drained and covered with a blotter and then pressed overnight witn a Williams Sheet Press at 100 psi. The sheets were the~ dried in an Emerson Speed Drier model 10, for 3 minutes at 240 F. The sheets were cured ~' in an oven at 105 C for 10 minutes and conditioned at room temperature overnight. The bursting strength was tested by the use of a B.F. Perkins hand-driven Mullen tester and an average of eight values was reported. The results are shown in Table 1, below.
TABLE 1: SYNERGISTIC EFFECT OF CATIONIC AND ANIONIC RESINS
CATIONIC ANIONIC ~ BURSTING STRENGTH
RESIN RESIN psi %Increase 17.23 0.2 0 19.66 14.1 0.4 0 20.77 20.5 0.2 0.2 22.31 29.5 0.6 0 22.06 28.0 0.4 0.2 23.75 37.8 0.2 0.4 22.56 30.9 -12~
, . ~
1047~ 7 RI 1651 CATIONIC ANIONIC BURSTING STRENGTH
_ SIN RESIN ~__ %Increase 0.8 0 24.55 42.5 0.6 0.2 26.76 55.3 0.4 0.4 26.83 55.7 1.0 0 24.88 44.4 0.8 0.2 ~ 28.04 62.7 -~
0.2 0.8 21.~0 27.0 1.0 0.2 29.44 70.9 ~ 1.5 ~ 20.18 17.1 It is apparent, on the basis of the above results, that the use of an anionic polymer in conjunction with cationic polymer provides a synergistic effect in terms of dry strength of the treated paper. It should also be noted that without cationic resin, the anionic resin gave a very low dry strength improvement of 17.1% even at a high resin level of 1.5%; note the last entry in the above table.
Example IV - Evaluation of Resins with Another Furnish Polymer samples prepared as in Examples I and II were - 20 used with a different furnish in a way similar to Example III.
The furnish was composed of 85% repulped corrugated waste and 15% repulped newspaper. The furnish, as received, had a Canadian Standard Freeness of 326~ ml, and a pH of 7.4 at a consistency of 0.25~. The results are summarized in Table 2, below.
, TABLE 2 CATIONIC ANIONIC BURSTING STRENGTH
RESIN RESIN - ~ - %Increase 0 0 19.8 0.4 0 20.9 5.6 0.3 0.1 ' 22.4 13.1 0.2 0.2 21,1 6.6 -13~
CATIIONIC ANIONIC BURSTING STRENGTH
RESIN RESIN ~ Increase 1.0 0 24.4 23.2 0.9 0.1 24.6 24.2 0.8 0.2 25.2 28.9 0.75 0.25 25.9 30.8 The snyergistic e~fect of the two resins is evident from the above data. As was already noted, it is preferred to add an excess of the cationic resin over the anionic resin.
This is demonstrated by the experiment where 0.2~ of each resin was used and the other experiments where an excess of cationic resin was added.
The invention herein has been described and illustrated with a number o~ examples which demonstrate synergysm of the cationic and anionic resins when used in combination. It should be understood, however, that minor modifications may be made without departing from the spirit of our invention and it is intended to have such minor modifications covered by the appended claims. An example of such modification is the use of an additional monomer or monomers in small amounts in the prep-aration of the resins which would not change the character of the resins for the purpose described herein.
solids 20.0%
Brookfield Viscosity (LVF #4/60/25C) 5,000 cps pH 5.2 Example III - Evaluation of Resins Effect of the additives on the strength of paper was evaluated by adding various amounts of the cationic and the anionic polymers prepared in accordance with Examples I and II, respectively. These polymers were added separately, and in con-junction with each other.
~047207 A refined unbleached kraft f~rnish from recycled kraft boxes was obtained from the stock chest of the paper machine of a local paper mill. The consistency was 3.5~, Cana~ian Standard Freeness was 426 ml, and the pH was 7Ø
This stock was diluted to a consistency of 0.25%.
To one liter aliquots of this stock slurry, various amounts of polymer samples prepared in Examples I and II
were added such that the'percentages of resin based on dry pulp were as shown in Table l.
This slurry was erptied into a Williams Sheet Mold containing sufficient water for the total solution to reach a standard volume. The water was drained and covered with a blotter and then pressed overnight witn a Williams Sheet Press at 100 psi. The sheets were the~ dried in an Emerson Speed Drier model 10, for 3 minutes at 240 F. The sheets were cured ~' in an oven at 105 C for 10 minutes and conditioned at room temperature overnight. The bursting strength was tested by the use of a B.F. Perkins hand-driven Mullen tester and an average of eight values was reported. The results are shown in Table 1, below.
TABLE 1: SYNERGISTIC EFFECT OF CATIONIC AND ANIONIC RESINS
CATIONIC ANIONIC ~ BURSTING STRENGTH
RESIN RESIN psi %Increase 17.23 0.2 0 19.66 14.1 0.4 0 20.77 20.5 0.2 0.2 22.31 29.5 0.6 0 22.06 28.0 0.4 0.2 23.75 37.8 0.2 0.4 22.56 30.9 -12~
, . ~
1047~ 7 RI 1651 CATIONIC ANIONIC BURSTING STRENGTH
_ SIN RESIN ~__ %Increase 0.8 0 24.55 42.5 0.6 0.2 26.76 55.3 0.4 0.4 26.83 55.7 1.0 0 24.88 44.4 0.8 0.2 ~ 28.04 62.7 -~
0.2 0.8 21.~0 27.0 1.0 0.2 29.44 70.9 ~ 1.5 ~ 20.18 17.1 It is apparent, on the basis of the above results, that the use of an anionic polymer in conjunction with cationic polymer provides a synergistic effect in terms of dry strength of the treated paper. It should also be noted that without cationic resin, the anionic resin gave a very low dry strength improvement of 17.1% even at a high resin level of 1.5%; note the last entry in the above table.
Example IV - Evaluation of Resins with Another Furnish Polymer samples prepared as in Examples I and II were - 20 used with a different furnish in a way similar to Example III.
The furnish was composed of 85% repulped corrugated waste and 15% repulped newspaper. The furnish, as received, had a Canadian Standard Freeness of 326~ ml, and a pH of 7.4 at a consistency of 0.25~. The results are summarized in Table 2, below.
, TABLE 2 CATIONIC ANIONIC BURSTING STRENGTH
RESIN RESIN - ~ - %Increase 0 0 19.8 0.4 0 20.9 5.6 0.3 0.1 ' 22.4 13.1 0.2 0.2 21,1 6.6 -13~
CATIIONIC ANIONIC BURSTING STRENGTH
RESIN RESIN ~ Increase 1.0 0 24.4 23.2 0.9 0.1 24.6 24.2 0.8 0.2 25.2 28.9 0.75 0.25 25.9 30.8 The snyergistic e~fect of the two resins is evident from the above data. As was already noted, it is preferred to add an excess of the cationic resin over the anionic resin.
This is demonstrated by the experiment where 0.2~ of each resin was used and the other experiments where an excess of cationic resin was added.
The invention herein has been described and illustrated with a number o~ examples which demonstrate synergysm of the cationic and anionic resins when used in combination. It should be understood, however, that minor modifications may be made without departing from the spirit of our invention and it is intended to have such minor modifications covered by the appended claims. An example of such modification is the use of an additional monomer or monomers in small amounts in the prep-aration of the resins which would not change the character of the resins for the purpose described herein.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. The process for the manufacture of paper of improved dry strength and negligible wet strength comprising forming an aqueous suspension having pH of 4 to 9 of fibrous cellulosic material containing a total of 0.1 to 5% of a cationic polymer and an anionic polymer in the respective weight ratio of from 99:1 to 50:50, the cationic polymer being a reaction product of a ketone, an aldehyde and a polyamine prepared at a temperature of 60 to 110°C and in presence of a catalytic amount of a strong inorganic acid; sheeting the cellulosic material to form a web; and drying the web; the mol ratio of reactants being from 1.8 to 4 mols of the aldehyde and from 0.1 to 1 mol of the polyamine per mol of the ketone; the anionic polymer is selected from the group consisting of (a) polymers of acrylamide and maleic acid or its anhydride in respective mol ratio of from 90:10 to 98:2 (b) polymers of acrylamide or methacrylamide with acrylic or methacrylic acid in respective mol ratio of from 99:1 to 75:25, and (c) mixtures of the two polymers; the ketone of the cationic polymer is selected from ketones containing from 3 to 8 carbon atoms per molecule with at least one reactive hydrogen at the alpha carbon position, the aldehyde is selected from aldehydes containing from 1 to 5 carbon atoms, and the polyamine is selected from alkylene diamines and polyalkylene polyamines containing from 2 to 10 carbon atoms in the alkylene moiety and from 2 to 6 amine groups; amount of the two polymers is based on the dry weight of the fibrous cellulosic material.
2. Process of claim 1 wherein the anionic polymer is a copolymer of acrylamide with maleic acid or maleic an-hydride; Brookfield viscosity of a 20% solids solution of the cationic polymer is from 10 cps, measured on LVF #2 spindle at 60 rpm and 95°C, to its gelation point; amount of the cationic polymer is from 0.05 to 3% and that of the anionic polymer is al? from 0.05 to 3% by weight of the dry cellulosic material;
and pH of the cationic polymer in aqueous medium is from 8 to 10.
and pH of the cationic polymer in aqueous medium is from 8 to 10.
3. Process of claim 2 wherein amount of the cationic polymer is from 0.1 to 2% and of the anionic polymer it is also from 0.1 to 2%; intrinsic viscosity of the anionic polymer measured in a 0.1 N NaCl solution at 25 C is in the range of 0.5 to 6 dl/g.
4. Process of claim 3 wherein the ketone is acetone, the aldehyde is formaldehyde and the amine is polyethylene poly-amine containing from 2 to 6 amine groups; amount of the acid used in the reaction is up to about 0.3 mol; relative amount of the cationic polymer to the anionic polymer is from 90:10 to 70:30;
and intrinsic viscosity of the anionic polymer is from 1.0 to 1.5 dl/g.
and intrinsic viscosity of the anionic polymer is from 1.0 to 1.5 dl/g.
5. Process of claim 4 wherein molar ratio of the reactants for preparing the cationic resin is 3 mols of for-maldehyde and 0.5 mols of polyethylene polyamine per mol of acetone; the acid is hydrochloric acid; the cationic polymer is prepared at reflux temperature and 20% aqueous solution thereof has Brookfield viscosity of 40 to 60 cps measured on LVF #2 spindle at 60 rpm and about 95°C.
6. Paper having improved dry strength and negligible wet strength comprising fibrous cellulosic material and a total of 0.1 to 5% of a cationic polymer and an anionic polymer in the respective weight ratio of from 99:1 to 50:50, the cationic polymer being a reaction product of a ketone, an aldehyde and a polyamine prepared at a temperature of 60 to 110°C and in presence of a catalytic amount of a strong inorganic acid, the mol ratio of reactants being from 1.8 to 4 mols of the aldehyde and from 0.1 to 1 mol of the polyamine per mol of the ketone; the anionic polymer is selected from the group consisting of (a) polymers of acrylamide and maleic acid or its anhydride in respective mol ratio of from 90:10 to 98:2, (b) polymers of acrylamide or methacrylamide with acrylic or methacrylic acid in respective mol ratio of from 99:1 to 75:25, and (c) mixtures of the two p? mers; the ketone of the cationic polymer is selected from ketones containing from 3 to 8 carbon atoms per molecule with at least one reactive hydrogen at the alpha carbon position, the aldehyde is selected from aldehydes containing from 1 to 5 carbon atoms, and the polyamine is selected from alkylene diamines and polyalkylene polyamines containing from 2 to 10 carbon atoms in the alkylene moiety and from 2 to 6 amine groups; amount of the two polymers is based on the dry weight of the fibrous cellulosic material.
7. Paper of claim 6 wherein the anionic polymer is a copolymer of acrylamide with maleic acid or maleic anhydride;
Brookfield viscosity of a 20% solids solution of the cationic polymer is from 10 cps, measured on LVF #2 spindle at 60 rpm and 95°C, to its gelation point; amount of the cationic polymer is from 0.05 to 3% and of the anionic polymer it is also from 0.05 to 3% by weight of the dry cellulosic material.
Brookfield viscosity of a 20% solids solution of the cationic polymer is from 10 cps, measured on LVF #2 spindle at 60 rpm and 95°C, to its gelation point; amount of the cationic polymer is from 0.05 to 3% and of the anionic polymer it is also from 0.05 to 3% by weight of the dry cellulosic material.
8. Paper of claim 7 where amount of the cationic polymer is from 0.1 to 2% and of the anionic polymer it is also from 0.1 to 2%; intrinsic viscosity of the anionic polymer measured in a 0.1 N NaCl solution at 25°C is in the range of 0.5 to 6 dl/g.
9. Paper of claim 8 wherein the ketone is acetone, the aldehyde is formaldehyde and the amine is polyethylene poly-amine containing from 2 to 5 amine groups; amount of the acid used in the reaction is up to about 0.3 mol per mol of acetone;
relative amount of the cationic polymer to the anionic polymer is from 90:10 to 70:30; and intrinsic viscosity of the anionic polymer is from 1.0 to 1.5 dl/g.
relative amount of the cationic polymer to the anionic polymer is from 90:10 to 70:30; and intrinsic viscosity of the anionic polymer is from 1.0 to 1.5 dl/g.
10. Paper of claim 9 wherein molar ratio of the reactants for preparing the cationic resin is 3 mols of for-maldehyde and 0.5 mol of polyethylene polyamine per mol of acetone; the acid is hydrochloric acid; the cationic polymer is prepared at reflux temperature and 20% aqueous solution thereof has Brookfield viscosity of 20 to 60 cps measured on LVF #2 spindle at 60 rpm and about 95°C.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA229,200A CA1047207A (en) | 1975-06-12 | 1975-06-12 | Paper with synergistic dry strength additives and process therefor |
| GB2294676A GB1555340A (en) | 1975-06-12 | 1976-06-03 | Paper with synergistic dry strength additives |
| FR7617830A FR2314297A1 (en) | 1975-06-12 | 1976-06-11 | HIGH DRY RESISTANCE PAPER DUE TO ADDITIVES EXERCISING A SYNERGIC ACTION AND ITS MANUFACTURING PROCESS |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA229,200A CA1047207A (en) | 1975-06-12 | 1975-06-12 | Paper with synergistic dry strength additives and process therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1047207A true CA1047207A (en) | 1979-01-30 |
Family
ID=4103331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA229,200A Expired CA1047207A (en) | 1975-06-12 | 1975-06-12 | Paper with synergistic dry strength additives and process therefor |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1047207A (en) |
| FR (1) | FR2314297A1 (en) |
| GB (1) | GB1555340A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10822462B2 (en) | 2016-09-15 | 2020-11-03 | Kemira Oyj | Paper product and method for increasing the strength thereof |
| CN110730841B (en) | 2017-06-16 | 2022-05-17 | 凯米拉公司 | Reinforcement system and method for the manufacture of a paper web comprising cellulosic fibers |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3002881A (en) * | 1956-11-09 | 1961-10-03 | Cons Mining & Smelting Co | Method of increasing the wet strength of cellulosic material and article formed thereby |
| US3332834A (en) * | 1965-11-03 | 1967-07-25 | American Cyanamid Co | Process of forming dry strength paper with cationic resin, polyacrylamide resin and alum complex and paper thereof |
| FR1521163A (en) * | 1966-04-29 | 1968-04-12 | American Cyanamid Co | New paper strengthening agents |
| NL6709649A (en) * | 1966-08-12 | 1968-02-13 | ||
| US3902958A (en) * | 1974-01-30 | 1975-09-02 | Nalco Chemical Co | Method of making improved paper and paper products |
-
1975
- 1975-06-12 CA CA229,200A patent/CA1047207A/en not_active Expired
-
1976
- 1976-06-03 GB GB2294676A patent/GB1555340A/en not_active Expired
- 1976-06-11 FR FR7617830A patent/FR2314297A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| GB1555340A (en) | 1979-11-07 |
| FR2314297B1 (en) | 1980-08-29 |
| FR2314297A1 (en) | 1977-01-07 |
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