CA1249903A - Composition and method of deinking of recycled cellulosic material - Google Patents
Composition and method of deinking of recycled cellulosic materialInfo
- Publication number
- CA1249903A CA1249903A CA000480828A CA480828A CA1249903A CA 1249903 A CA1249903 A CA 1249903A CA 000480828 A CA000480828 A CA 000480828A CA 480828 A CA480828 A CA 480828A CA 1249903 A CA1249903 A CA 1249903A
- Authority
- CA
- Canada
- Prior art keywords
- precursor
- composition according
- resin
- pulp
- weight
- 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
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/02—Working-up waste paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/02—Working-up waste paper
- D21C5/025—De-inking
- D21C5/027—Chemicals therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/64—Paper recycling
Abstract
A B S T R A C T
A method for deinking recycled waste cellulosic material such as newsprint comprises pulping the waste in the presence of an aqueous dispersion of a resin precursor, curable in said dispersion and curing the resin precursor during the pulping operation.
A method for deinking recycled waste cellulosic material such as newsprint comprises pulping the waste in the presence of an aqueous dispersion of a resin precursor, curable in said dispersion and curing the resin precursor during the pulping operation.
Description
BhCKGROUND
An increasingly large proportiGn of cellulosic pulp for the paper industry is produced from recycled waste cellulosic materlal~
especially repulped newsprint and maga~ines. Pulp containin~ eith~r of these wastes is ncrmally contaminated with pi~ments derived from the ink, which must be removed in order to obtain adequate br,ghtness.
Conventional1y, particles of pigment are removed by froth flotation, using the surfactants naiurally present in the pulp in order to promote foaming, or, less çommonly, adding extraneous surfact~nts and/or foam boosters. An alter~ative is to use various solvents and/or surfactants to wash the pigment out of the pulp.
Neither of these processes has proved capable of removing sufficient of the print to provide max;mum realisable br;ghtness.
In an attempt to improve the degree cf separation of the print, various proposals have been made to agglGmerate the print or adsorb it onto relativel~ large particles which will be more readily separated by flotation, or even by centrifugation or screening. All these proposals have, however, had serious drawbacks which have prevented their adoption commercially, despite the recognised inadequacy of the conventional washing and flotation technology.
THE PRIOR ART
FR 1379252 and USP 3377234 describe the addition of surfactants to the pulping liquor prior to pulping. This approach ~oes not result in ccmplete separation of print. USP 4~13505 and USP 4147616 describe the precipitation of calcium soap in the pulper to adsorb the print, followed by centrifugal separation of the resulting curds. This approach is only partially successful.
C)3 USP 3846227 and llSP 3963~60 describle the use of N-cyclohexyl pyrrolidone as solvent in the pu7ping stage, to promote re~oval of print. The process requires relatively high temperatu~es of about 730r, which suhstantially increases the energy ccst of the process.
and causes unacceptaDle solvent losses.
GB 20803S4 has proposed ~he addition of polymers to pulp at temperatures above their sof~ening point in order to remove adhesives from reeycled pulp. High temperatures are required, and efficient deinking is not alleged.
THE PROBLEM
Waste paper pulp is a chemically and physica11y complex system which is highly variable in an unpredictable manner. Little is known about the mechanism by which known deinking processes operate.
The approach has ~itherto been largely empirical.
We have therefore set oùt to discover the reasons for the inadequate performance of prior art processes.
By far, the major pigment present in repulped paper, and the one with the greatest effect on the final brightness, is carbon black, which is also one of the more intractable in its response to deinking processes. In the following discussion reference is specifially made to carbon black. The comments are, however, generally applicable to other pigments.
We believe, without wishing to be bound thereby, that carbon black is present in print, especially in newspapers, as particles weakly held in an oily matrix. During pulping we believe that this disintegrates, releasing small particles which lodge in the fibrillar surfacP of the fibres. We believe that the particles, once entrapped, are particularly difficult to remove by known deinking technolO9W-~'L~3 THE IN~ENTI0N
We have n~l disco~ered that substantlally improved deinking canbe obtained by pulping ~aste paper in an aqueou~ suspension of a non-fibre-substantive~ rocm temperature vulcanisable resin, and curing the resin in situ. I~e believe that, in our invention, any pigmRnt particles may hecome rapidly coated with uncured or partially cured resin, whi~h inhibi~ disintegration and subsequent redeposition onto the cellulosic fibres, and which on curing, causes the particles to form agglomerates, which are relatiYely resis~ant to com~ nution and are separable from the pulp by conventional means such as washingl flotation, centrifugation or screening.
According to one embodiment, our invent;on provides an aqueous dispersion of at least one fluid, non-fibre-substantive resin precursor9 curable in aqueous dispersion, and sufficient of a curing catalyst to effect curing of the composition, in the dispersion.
Preferably the composition contains a dispersant for the resin precursor. We have further discovered that the proportion of the curable resin required can be substantially reduced by admixing the composition wi~h an inert exten~er or diluent, thereby improving the economics of the process.
According to a second embodiment, our inYentiOn therefore provides a composition comprising from 10 to 85% by weight thereof, of a fluid, non-fibre-substantive resin precursor, curable in aqueous dispersion, at least ~ by weight of the composition of an inert, non-fibre-substan~ive, fluid diluent and an effective amount of a dispersant for the composition.
According to a further embodiment, our invention provides a method of pulping recycled cellulosic materia7, contaminated with print, which comprises macerating the material in an aqueous dispersion containing sufficient of a third, non-fibre-substantive, resin precursor, curable in said dispersion, to facilitate subsequent deinking, and curing said resin precursor during said maceration.
4 ~ 303 THE RESIN PRECUR
The resin precursor according to our invention may be any non~
fibre-substantive fluid which is curable in aqueous suspension, and preferably in aqueous alkaline suspension. In particular it is desirable that the precursor should be curable at temperatures below 50C, preferably at room temperature. The resin preoursor is preferably a sufficiently hydrophsbic material not to ~e reabily adsorbed onto the cellulosic fibres, but is desirably compatible with the print. Typically the resin prec~rsor comprises a mixture of a fluid, prPpolymer having at least two reactive functional groups per mNlecu7e and a cross linking agent able to react with the functional groups, at least in the presence of a suitabl~ catalyst.
Where the polymer system is capable of curing in the pulper, in the absence of a catalyst, the resin precursor will normally be fonned in situ, the cross linking agent being added to the prepolymer on or shortly before addition to the pulper.
Mcst preferably, the resin is a room temperature vulcanisable organopolysiloxane. Particularly sui~able are mixtures of a d~hydroxy poly (dialkylsiloxane) polymer with a poly (alkylhydrosiloxane) cross-linking agent. Preferably, the alkyl groups in each case are lower (e.g. 1 to 4 carbon) alkyl groups, typically methyl groups. An alternative curable resin system for use according to the present invention comprises an oligomeric hydroxy acrylate prepolymer cross linked with a di isocyanate, e.y. a hydroxy ethyl acrylate resin mixed with 1,6-hexamethylene di isocyanate.
Typically the prepolymer has a mean molecular weight of ,rom 5JOOO to 70,000 preferably from 10,000 to 50,000 e.g. 30,000 to 45,000. We particularly prefer prepolymers comprising a wide spread of molecular ~eights e.g. a mixture of a short chain prepolymer M.W.
3,000 to 12,000 a long chain prepolymer M.W. 50,000 to 70,000.
)3 The cross-linklng agen~ typically has a mean molecular weight of from 1,000 to 5,000. Typically ~he cross-linking agent is present in a proportion of from 1:10 to 1~:1; preferably from 1:2 to
An increasingly large proportiGn of cellulosic pulp for the paper industry is produced from recycled waste cellulosic materlal~
especially repulped newsprint and maga~ines. Pulp containin~ eith~r of these wastes is ncrmally contaminated with pi~ments derived from the ink, which must be removed in order to obtain adequate br,ghtness.
Conventional1y, particles of pigment are removed by froth flotation, using the surfactants naiurally present in the pulp in order to promote foaming, or, less çommonly, adding extraneous surfact~nts and/or foam boosters. An alter~ative is to use various solvents and/or surfactants to wash the pigment out of the pulp.
Neither of these processes has proved capable of removing sufficient of the print to provide max;mum realisable br;ghtness.
In an attempt to improve the degree cf separation of the print, various proposals have been made to agglGmerate the print or adsorb it onto relativel~ large particles which will be more readily separated by flotation, or even by centrifugation or screening. All these proposals have, however, had serious drawbacks which have prevented their adoption commercially, despite the recognised inadequacy of the conventional washing and flotation technology.
THE PRIOR ART
FR 1379252 and USP 3377234 describe the addition of surfactants to the pulping liquor prior to pulping. This approach ~oes not result in ccmplete separation of print. USP 4~13505 and USP 4147616 describe the precipitation of calcium soap in the pulper to adsorb the print, followed by centrifugal separation of the resulting curds. This approach is only partially successful.
C)3 USP 3846227 and llSP 3963~60 describle the use of N-cyclohexyl pyrrolidone as solvent in the pu7ping stage, to promote re~oval of print. The process requires relatively high temperatu~es of about 730r, which suhstantially increases the energy ccst of the process.
and causes unacceptaDle solvent losses.
GB 20803S4 has proposed ~he addition of polymers to pulp at temperatures above their sof~ening point in order to remove adhesives from reeycled pulp. High temperatures are required, and efficient deinking is not alleged.
THE PROBLEM
Waste paper pulp is a chemically and physica11y complex system which is highly variable in an unpredictable manner. Little is known about the mechanism by which known deinking processes operate.
The approach has ~itherto been largely empirical.
We have therefore set oùt to discover the reasons for the inadequate performance of prior art processes.
By far, the major pigment present in repulped paper, and the one with the greatest effect on the final brightness, is carbon black, which is also one of the more intractable in its response to deinking processes. In the following discussion reference is specifially made to carbon black. The comments are, however, generally applicable to other pigments.
We believe, without wishing to be bound thereby, that carbon black is present in print, especially in newspapers, as particles weakly held in an oily matrix. During pulping we believe that this disintegrates, releasing small particles which lodge in the fibrillar surfacP of the fibres. We believe that the particles, once entrapped, are particularly difficult to remove by known deinking technolO9W-~'L~3 THE IN~ENTI0N
We have n~l disco~ered that substantlally improved deinking canbe obtained by pulping ~aste paper in an aqueou~ suspension of a non-fibre-substantive~ rocm temperature vulcanisable resin, and curing the resin in situ. I~e believe that, in our invention, any pigmRnt particles may hecome rapidly coated with uncured or partially cured resin, whi~h inhibi~ disintegration and subsequent redeposition onto the cellulosic fibres, and which on curing, causes the particles to form agglomerates, which are relatiYely resis~ant to com~ nution and are separable from the pulp by conventional means such as washingl flotation, centrifugation or screening.
According to one embodiment, our invent;on provides an aqueous dispersion of at least one fluid, non-fibre-substantive resin precursor9 curable in aqueous dispersion, and sufficient of a curing catalyst to effect curing of the composition, in the dispersion.
Preferably the composition contains a dispersant for the resin precursor. We have further discovered that the proportion of the curable resin required can be substantially reduced by admixing the composition wi~h an inert exten~er or diluent, thereby improving the economics of the process.
According to a second embodiment, our inYentiOn therefore provides a composition comprising from 10 to 85% by weight thereof, of a fluid, non-fibre-substantive resin precursor, curable in aqueous dispersion, at least ~ by weight of the composition of an inert, non-fibre-substan~ive, fluid diluent and an effective amount of a dispersant for the composition.
According to a further embodiment, our invention provides a method of pulping recycled cellulosic materia7, contaminated with print, which comprises macerating the material in an aqueous dispersion containing sufficient of a third, non-fibre-substantive, resin precursor, curable in said dispersion, to facilitate subsequent deinking, and curing said resin precursor during said maceration.
4 ~ 303 THE RESIN PRECUR
The resin precursor according to our invention may be any non~
fibre-substantive fluid which is curable in aqueous suspension, and preferably in aqueous alkaline suspension. In particular it is desirable that the precursor should be curable at temperatures below 50C, preferably at room temperature. The resin preoursor is preferably a sufficiently hydrophsbic material not to ~e reabily adsorbed onto the cellulosic fibres, but is desirably compatible with the print. Typically the resin prec~rsor comprises a mixture of a fluid, prPpolymer having at least two reactive functional groups per mNlecu7e and a cross linking agent able to react with the functional groups, at least in the presence of a suitabl~ catalyst.
Where the polymer system is capable of curing in the pulper, in the absence of a catalyst, the resin precursor will normally be fonned in situ, the cross linking agent being added to the prepolymer on or shortly before addition to the pulper.
Mcst preferably, the resin is a room temperature vulcanisable organopolysiloxane. Particularly sui~able are mixtures of a d~hydroxy poly (dialkylsiloxane) polymer with a poly (alkylhydrosiloxane) cross-linking agent. Preferably, the alkyl groups in each case are lower (e.g. 1 to 4 carbon) alkyl groups, typically methyl groups. An alternative curable resin system for use according to the present invention comprises an oligomeric hydroxy acrylate prepolymer cross linked with a di isocyanate, e.y. a hydroxy ethyl acrylate resin mixed with 1,6-hexamethylene di isocyanate.
Typically the prepolymer has a mean molecular weight of ,rom 5JOOO to 70,000 preferably from 10,000 to 50,000 e.g. 30,000 to 45,000. We particularly prefer prepolymers comprising a wide spread of molecular ~eights e.g. a mixture of a short chain prepolymer M.W.
3,000 to 12,000 a long chain prepolymer M.W. 50,000 to 70,000.
)3 The cross-linklng agen~ typically has a mean molecular weight of from 1,000 to 5,000. Typically ~he cross-linking agent is present in a proportion of from 1:10 to 1~:1; preferably from 1:2 to
2:1, most preferably 3:4 to ~:3 e.g. 1:;L by weisht based on the difunctional polymer.
THE DISPERSAIIT
Any surfactant or dispersant which is water soluble or miscible and also miscible with the relatively hydrophobic resin precursor may be employed. Examples of dispersants for org2no polysiloxane resin precursors are non-ionic surfactants such as polyalkoxylated organopslysiloxanes, e~g~ a poly (dimethylsiloxane~
poly tethyleneglYcol) ether, and poly ethoxylated sorbitan monoalkanoates, and cat~onic surfactants. Anionic surfactants are less preferred.
Particularly preferred, however are ,ilm forming dispersants and especially polymeric protective colloids such as polyviny7 alcohol, carbcxymet~ylcellulose, polyv~nylpyrrolidone or cellulose acetate.
The proportion of dispersan~ is sufficient to form a stable dispersion for the resin precursor in water. Amounts in excess of the minimum required to disperse the resin percursor are preferably avoided on economic grounds. Typically the dispersant is present in a proportion of from 0.1 to 20~ by weight of the resin precursor, e.g. 3 to 7%. We do not exclude the possibility of dispersing the resin precursor without a dispersant, or using the dispersant action of normal components of the pulp adventitiously present in the pulper.
THE DILUENT
The diluent is optionally, present in any proportion up to about 95% by weight of the composition~ preferably 5 to 90~, e.g. 55 to 80~ especially 65 to 75%.
The diluent may be any inert oil which is sufficiently hydrophobic to be non-fibre-substantive, and to be miscible wi~h the resin prerursor. Typical examples of diluents include polydimethylsiloxanes with terminal methyl groups and hydrocarbon oils. The diluent is preferably sufficiently fluid for the composition to be pourable, but sufficiently viscous to provide effective protection to particles of print in the pulp to prevent comminution and/or entrapment in the early stages of pulping and to ensure a mechanic~lly strong cured agglomerate.
THE CATALYST
The catalyst may be any catalyst capable of catalysing the curing of the resin precursor in aqueous susp~nsionJ preferably at room temperature. Particularly preferred are organotin catalysts such as the dialkyltin dialkanoates. Preferably the two alkyl groups are lower alkyl groups having, for example, 2 to 4, preferably 4, carbon atoms and the two alkanoyl groups have from 2 to 20 carhon atoms, preferably 8 to 14l e.g. dibutyltin bis (ethylhexanoate) or dibutyltin dilaurate.
The activity and the volatility of the catalyst increase with decreasing carbon number of the alkanoyl groups. We prefer a catalyst which is sufficiently active to cure the resin precursor fully within the normal pulping period, e.g. 15 to 40 minutes. More active catalysts, e.g. dibutyltin diacetate, although operative are less preferred.
~Z~ )3 The catalys~ may be used as d solu~icn in an srganic solvenS
such as trichlorethylene, bu~ we prefer to use aqueous based emulsions of catalyst, which are rolnmercially available and which have been iound to give better actiYity in the aqueous pulping liquor.
In general we believe that the brightness of the pulp tends to reach a peak at the completion of the curing period and may thereafter decline if pulping is continued. We therefore prefer catalysts which give a curing time approximately equal to the pulping time rather than those which give substantially complete curing at an early stage in the pulping process.
We prefer to use a catalyst~ even with systems which are capable of curing in the absence of a catalyst at the temperatures obtaining in the pulper, although it is not essential to our inventisn.
THE PULPING LIQU0_ Preferably the resin precursor is dispersed in water, in the presence of the catalyst (or of added cross linking agen~9 where no catalyst is required) and allowed to precure for a short period.
e.g. 10 secs ~o S minu~es, preferably 0.5 to 1 minutes and at a pH
of preferably 8 to 12, before adding the waste. Typically the precure is from 1 to lOX o~ total curing time. Preferably the resin precursor is used in a proportion of 0.1 to 10% based on the weigh~
of pulp solids, more preferably 1 to 5~, e.g. 1.5 to 4%.
The catalyst may be present in a proportion of from 0.1 to 50%
based on the wei~ht of resin precursor, preferably 0.5 to 20%, e.g.
1 to 10~.
The pulping liquor is preferably alkaline. Typically the pulper conten~s should have a pH of 8 to 12.5, e.g. 9 to 10. This may be achieved using for example sodium hydroxide, sodium carbonate, scdium silicate or mixtures thereof. The resin precursor ~ ~L~ O 3 and cat.dlys~ may be suspended directly in the pulping liquor, or alternatively a more concentra~ed suspension m~y be prepared and added ~o the pulping liquor shortly before pulping.
T~E PULPING QPERATION
The furnish for the pulp may comprise newsprint and/or magazines and/or other ink contaminated cellulosic wastes. The furnish preferably comprises a mixture of newsprint and magazines, e.g. comprising 10 to 60~ by weight of magazines. However the process is sperable with 100% newsprint, a furnish that is partic~larly difficult to deink satisfactorily with existing technolo~v. The waste is macera~ed with the pulping liquor ~or from 10 to 60 mins, preferably 15 to 40 mins, at temperature which may typically be in the range 5 to 60~, preferably 20 to 50C9 e.g.
35C. The pulp may contain from 2 to 25~ solids more usually 5 to 15~.
SEQUESTRANTS
We have discovered that the brightness of pulp deinked according to our process is substantially enhanced by the presence in the pulping liquor of a sequestrant for alkaline earth ~etal and especially for calcium, e.g. ethylenediamine tetracetic acid; or phosphates~ condensed phosphates or phosphonates, especially sodium tripolyphosphate, or silicates. This constitutes a preferred aspect of our invention. We prefer that the sequestrant should be present in amounts up to the stoichiometric amount based on the total sequesterable alkaline earth metal ion present in the pulp.
MISCELLANEOUS ~DDITIVES
. ~
It is desirable that the cured resin particles should have a physical form such that they are readily separable from the pulp.
For example they may differ substantially in density from the aqueous medium, preferably being substantially lighter, to facilitate centrifugal separation or they may be of a sufficient size to pernit effective screening. The formPr may be achieved for example by selec~ion of a low density extender, or by incorporating a blowins agent into the resin precursor. The latter may be a volatile liquid such as a fluorocarbon whict~ .s evaporated by the exothermic curing reaction to for~ expandPd particles.
Alternatively, either the size or the density may be contro71ed by the addition of solid particles or granules of polymer.
Preferably the particles are of a low density material such as expanded polystyrene and/or are of a sufficient size to be separable by screenîng. They preferably have a surface upon which the resin precursor and pigment will readily coagulate.
We have found in par-ticular that separated coarse particles, either of an added polymer with print agglomerated on the surface, or of the cured agglomerated resin itself, can advantageously be recycled to the pulper in order to provide a more complete separation of the agglomerated print.
According to a further embodiment of our invention, therefore, recycled cellulosic ma~erial, contaminated with printJ is repulped in a pulper in the presence of a dispersed curable resin which is non-substantive to the cellulose, but substantive to the print, in conditions adapted to effect curing of the resin and agglomeration of the print thereby; pulp is withdrawn from the pulper; cured resin is separated from the pulp; and a part of the cured resin is recycled to the pulper.
Surfactants, foam stabilizers or anti-foams may be added to the pulper, or subsequently, to promote or control foaming.
)3 SEPARATION
The coagulated print may be s~parated fr~n the pulp using ar~
of the known prccedures, depending upon the physical form of the cured particles.
The particles may be separated using conventional froth flotation. If necessary foam boos~ers and/or inhibitors may be added ~o the pulp to regulate ~he degree of foamimg. Alternatively the agglor~rated print may be removed by washing e.g. by dewatering and reslurrying the pulp.
If the particles differ sufficiently in density ~ran the pulp they may be separated centrifugally, while sufficiently large particles may be separated by screening.
Typically, the pulp is diluted to a solids content of less than 2~ by weight and screened to remove large particles. Any ink containing particles remaining in the pulp may then be separated by washing, centrifugation and/or flotation.
The invention will be illustrated by the following Examples:
Except where stated to the contrary, the exarnples used the following conditions:
Resin precursor :-50% by weight hydroxy-functional polydimethylsiloxane 45X by weight Si-H functional polydimethylsiloxane prepclymer 5~ by weight polyethyleneoxy-/polypropyleneoxy-functional polydimeth~ylsiloxane.
Pulper consistency : 4%
Initial pulper pH : 10.5
THE DISPERSAIIT
Any surfactant or dispersant which is water soluble or miscible and also miscible with the relatively hydrophobic resin precursor may be employed. Examples of dispersants for org2no polysiloxane resin precursors are non-ionic surfactants such as polyalkoxylated organopslysiloxanes, e~g~ a poly (dimethylsiloxane~
poly tethyleneglYcol) ether, and poly ethoxylated sorbitan monoalkanoates, and cat~onic surfactants. Anionic surfactants are less preferred.
Particularly preferred, however are ,ilm forming dispersants and especially polymeric protective colloids such as polyviny7 alcohol, carbcxymet~ylcellulose, polyv~nylpyrrolidone or cellulose acetate.
The proportion of dispersan~ is sufficient to form a stable dispersion for the resin precursor in water. Amounts in excess of the minimum required to disperse the resin percursor are preferably avoided on economic grounds. Typically the dispersant is present in a proportion of from 0.1 to 20~ by weight of the resin precursor, e.g. 3 to 7%. We do not exclude the possibility of dispersing the resin precursor without a dispersant, or using the dispersant action of normal components of the pulp adventitiously present in the pulper.
THE DILUENT
The diluent is optionally, present in any proportion up to about 95% by weight of the composition~ preferably 5 to 90~, e.g. 55 to 80~ especially 65 to 75%.
The diluent may be any inert oil which is sufficiently hydrophobic to be non-fibre-substantive, and to be miscible wi~h the resin prerursor. Typical examples of diluents include polydimethylsiloxanes with terminal methyl groups and hydrocarbon oils. The diluent is preferably sufficiently fluid for the composition to be pourable, but sufficiently viscous to provide effective protection to particles of print in the pulp to prevent comminution and/or entrapment in the early stages of pulping and to ensure a mechanic~lly strong cured agglomerate.
THE CATALYST
The catalyst may be any catalyst capable of catalysing the curing of the resin precursor in aqueous susp~nsionJ preferably at room temperature. Particularly preferred are organotin catalysts such as the dialkyltin dialkanoates. Preferably the two alkyl groups are lower alkyl groups having, for example, 2 to 4, preferably 4, carbon atoms and the two alkanoyl groups have from 2 to 20 carhon atoms, preferably 8 to 14l e.g. dibutyltin bis (ethylhexanoate) or dibutyltin dilaurate.
The activity and the volatility of the catalyst increase with decreasing carbon number of the alkanoyl groups. We prefer a catalyst which is sufficiently active to cure the resin precursor fully within the normal pulping period, e.g. 15 to 40 minutes. More active catalysts, e.g. dibutyltin diacetate, although operative are less preferred.
~Z~ )3 The catalys~ may be used as d solu~icn in an srganic solvenS
such as trichlorethylene, bu~ we prefer to use aqueous based emulsions of catalyst, which are rolnmercially available and which have been iound to give better actiYity in the aqueous pulping liquor.
In general we believe that the brightness of the pulp tends to reach a peak at the completion of the curing period and may thereafter decline if pulping is continued. We therefore prefer catalysts which give a curing time approximately equal to the pulping time rather than those which give substantially complete curing at an early stage in the pulping process.
We prefer to use a catalyst~ even with systems which are capable of curing in the absence of a catalyst at the temperatures obtaining in the pulper, although it is not essential to our inventisn.
THE PULPING LIQU0_ Preferably the resin precursor is dispersed in water, in the presence of the catalyst (or of added cross linking agen~9 where no catalyst is required) and allowed to precure for a short period.
e.g. 10 secs ~o S minu~es, preferably 0.5 to 1 minutes and at a pH
of preferably 8 to 12, before adding the waste. Typically the precure is from 1 to lOX o~ total curing time. Preferably the resin precursor is used in a proportion of 0.1 to 10% based on the weigh~
of pulp solids, more preferably 1 to 5~, e.g. 1.5 to 4%.
The catalyst may be present in a proportion of from 0.1 to 50%
based on the wei~ht of resin precursor, preferably 0.5 to 20%, e.g.
1 to 10~.
The pulping liquor is preferably alkaline. Typically the pulper conten~s should have a pH of 8 to 12.5, e.g. 9 to 10. This may be achieved using for example sodium hydroxide, sodium carbonate, scdium silicate or mixtures thereof. The resin precursor ~ ~L~ O 3 and cat.dlys~ may be suspended directly in the pulping liquor, or alternatively a more concentra~ed suspension m~y be prepared and added ~o the pulping liquor shortly before pulping.
T~E PULPING QPERATION
The furnish for the pulp may comprise newsprint and/or magazines and/or other ink contaminated cellulosic wastes. The furnish preferably comprises a mixture of newsprint and magazines, e.g. comprising 10 to 60~ by weight of magazines. However the process is sperable with 100% newsprint, a furnish that is partic~larly difficult to deink satisfactorily with existing technolo~v. The waste is macera~ed with the pulping liquor ~or from 10 to 60 mins, preferably 15 to 40 mins, at temperature which may typically be in the range 5 to 60~, preferably 20 to 50C9 e.g.
35C. The pulp may contain from 2 to 25~ solids more usually 5 to 15~.
SEQUESTRANTS
We have discovered that the brightness of pulp deinked according to our process is substantially enhanced by the presence in the pulping liquor of a sequestrant for alkaline earth ~etal and especially for calcium, e.g. ethylenediamine tetracetic acid; or phosphates~ condensed phosphates or phosphonates, especially sodium tripolyphosphate, or silicates. This constitutes a preferred aspect of our invention. We prefer that the sequestrant should be present in amounts up to the stoichiometric amount based on the total sequesterable alkaline earth metal ion present in the pulp.
MISCELLANEOUS ~DDITIVES
. ~
It is desirable that the cured resin particles should have a physical form such that they are readily separable from the pulp.
For example they may differ substantially in density from the aqueous medium, preferably being substantially lighter, to facilitate centrifugal separation or they may be of a sufficient size to pernit effective screening. The formPr may be achieved for example by selec~ion of a low density extender, or by incorporating a blowins agent into the resin precursor. The latter may be a volatile liquid such as a fluorocarbon whict~ .s evaporated by the exothermic curing reaction to for~ expandPd particles.
Alternatively, either the size or the density may be contro71ed by the addition of solid particles or granules of polymer.
Preferably the particles are of a low density material such as expanded polystyrene and/or are of a sufficient size to be separable by screenîng. They preferably have a surface upon which the resin precursor and pigment will readily coagulate.
We have found in par-ticular that separated coarse particles, either of an added polymer with print agglomerated on the surface, or of the cured agglomerated resin itself, can advantageously be recycled to the pulper in order to provide a more complete separation of the agglomerated print.
According to a further embodiment of our invention, therefore, recycled cellulosic ma~erial, contaminated with printJ is repulped in a pulper in the presence of a dispersed curable resin which is non-substantive to the cellulose, but substantive to the print, in conditions adapted to effect curing of the resin and agglomeration of the print thereby; pulp is withdrawn from the pulper; cured resin is separated from the pulp; and a part of the cured resin is recycled to the pulper.
Surfactants, foam stabilizers or anti-foams may be added to the pulper, or subsequently, to promote or control foaming.
)3 SEPARATION
The coagulated print may be s~parated fr~n the pulp using ar~
of the known prccedures, depending upon the physical form of the cured particles.
The particles may be separated using conventional froth flotation. If necessary foam boos~ers and/or inhibitors may be added ~o the pulp to regulate ~he degree of foamimg. Alternatively the agglor~rated print may be removed by washing e.g. by dewatering and reslurrying the pulp.
If the particles differ sufficiently in density ~ran the pulp they may be separated centrifugally, while sufficiently large particles may be separated by screening.
Typically, the pulp is diluted to a solids content of less than 2~ by weight and screened to remove large particles. Any ink containing particles remaining in the pulp may then be separated by washing, centrifugation and/or flotation.
The invention will be illustrated by the following Examples:
Except where stated to the contrary, the exarnples used the following conditions:
Resin precursor :-50% by weight hydroxy-functional polydimethylsiloxane 45X by weight Si-H functional polydimethylsiloxane prepclymer 5~ by weight polyethyleneoxy-/polypropyleneoxy-functional polydimeth~ylsiloxane.
Pulper consistency : 4%
Initial pulper pH : 10.5
3~Z'~ 3 Initial pulper temperature : 3G~C.
Pulpin~ time : 25 minutes.
Resin addition leYel: 2% on fibre by weight.
Method of addi~ion : resin mixture added to water and dispersed prior to addition of fibre, caustic soda and catalyst.
Furnish : 100% newsprint.
~xample 1 Using 0.2~, by weight of fibre, of sodium dibutyltin dilaurate as catalyst in a laboratory test run, the ex-pulper brishtness was 49% compared with 41% in the absence of resin.
Example 2 Example l was repeated using 100g magazines in place of newsprint. Ex-pulper brightness was 57% compared with 54~ in the absence of resin.
Example 3 Example 1 was repeated using iO% by weight newsprint, 50~
maga2ines as furnish. Ex-pulper brightness was 52% compared with 47% in the absence of resin.
Examples ~-6 Using 1.5%, by weight of fibre, of different cata1ysts results were:
No resin - 45% brightness;
1~
Example 4 dibutyltin diac.etate 55.5~ brightness;
Example 5 - dibutyltln di ,aurate 56.5~ brigh~ness;
Example 6 - dibutyltin bis (2-ethylhexanoate) (in ethanol~ 58%
brightness.
Example 7 Figure 1 represents the variation in pulp brightness wi~h ~ime in a mill trial, using dibutyltin diacetate catalyst with 1 ton of n~wsprint, at a consistency of 12 to 15~. The lowest curve is a comparative run with no resin added. The middle curve is wi~h 2%
recin and 0.25% catalyst, based on the weight of fibre, ar,d t~e highest curve is with 4b resin and 0.5~ catalyst based on the weight of fibre.
Example 8 Fisure 2 shows the effects of varying temperature on 6 experimen~al runs using 4g resin and 1.5~ by weight dibutyltin diacetate based on the weight of fibre.
Example 9 Figure 3 shows the effect of increasing resin concentration using 1.5~ by weight of dibutyltin diacetate based on the weight of fibre.
Example 10 Example 1 was repeated adding expanded polystyrene beads of from 1 to lOmm. diameter to the dispersed resin precursor immediately prior to the addition of the fibre. The beads were readily separated from the pulp and gave a substantial mprovem,ent in agglomeration and separation of the print~ Optimum results were ~L;~ 3 obtained with 1-2mm~ beadsO The separated beads were rec~cled ~o the pulper and the experiment repeated. The recycled beads provided a substantially eqLIivalent improvement in the agglomeration of the print to that provided by the original uncontaminated beads~
Example 11 Example 1 was repeated. Particles of aggl~merated p int were separated from the pulp and 50~ of the separated particles were recycled to the pulper and the example repeated again. On the second run improved agglomeration and easier separation was observed.
Examples 12 and 13 An acrylic resin precursor was used in the Examples 12 and 13 consisting of wt~ Substance Function Carrier Trade Mark 65 hydroxyethyl- prepolymer 50X in acrylate ~utylacetate "DURASOL" 346 30 hexamethylene-1,6-diisocyanate cross linker xylene "DESMODUR" N75 5 ethylene glycol/
propylene glycol dispersant "GLYCOL B"
hydroxymethyl siloxane copolymer This was compared with the silicone resin precursor of Example 1 as follows:
~.2 ~ 3 Example 12 Furnish 100~ News Catalyst Dibut~ltindilaurate (1~ on fibre addition) Brightness R 457Ex-Dulper 2nfinite wash Caustic only 37 49 3% Acrylate/caustic 45 5i~
2~ Silicone/caustic 47 55 Examp 1 ~ 13 Furnish 50/50 News/magazines Catalyst Dibutyltindilaurate (1~ on fibre addition~
Brightness R 457 Ex-pulper After flotation Caustic only 50 54-~
2~ Acrylate RTV/caustic 52 63 2~ Silicone RTV/caustic 56 62 Example 14 To illustrate the effects of including a non-functional extender in the resin example 1 was repeated adding various proportions of methyl functional polydimethyl siloxane to the reactive prepolymer9 with the following results:-by wt. reactive prepolymer Ex pulper brightness 51.5 51.8 51.
50.0 Comparative (no resin~ 40.7 ~ 3 Example 15 A prepolymer emulsion was prepared comprising:
Dihydroxy poly~dimethyl siloxane) n=49-144 (mean MW = 7566) 109 Dihydroxy poly(d~.methyl siloxane) n= 850 (mean MW = 63066) 409 Poly(methyl hydrosiloxane) n=40 (mean MW = 2562) 459 5~ aqueous solution of polyvinyl alcohol 1659 A catalyst emulsion having 33Z by wt. of solids was prepared separately containing:
dibutyl tin dilaurate 609 polyvinyl alcohol 79 water 133g 1900 ml of wa~er and 69 prepolymer emulsion (lZ resin based on the weight of fibre) were stirred in a pulper with 13 ml concentrated sodium hydroxide solution and 0.3 ml of the catalyst emulsion (0.05% based on the weight of fibre) at room temperature for a 30 second precure period. 2.36 gm of waste newsprint were then added to provide a pulp having a consistency of 11%.
After 25 minutes pulping the pulp was washed and compared with a control run using sodium hydroxide solution only.
Ex pulper brightness Washed brightness Control 3~.5 42.8 Example 15 46.3 51
Pulpin~ time : 25 minutes.
Resin addition leYel: 2% on fibre by weight.
Method of addi~ion : resin mixture added to water and dispersed prior to addition of fibre, caustic soda and catalyst.
Furnish : 100% newsprint.
~xample 1 Using 0.2~, by weight of fibre, of sodium dibutyltin dilaurate as catalyst in a laboratory test run, the ex-pulper brishtness was 49% compared with 41% in the absence of resin.
Example 2 Example l was repeated using 100g magazines in place of newsprint. Ex-pulper brightness was 57% compared with 54~ in the absence of resin.
Example 3 Example 1 was repeated using iO% by weight newsprint, 50~
maga2ines as furnish. Ex-pulper brightness was 52% compared with 47% in the absence of resin.
Examples ~-6 Using 1.5%, by weight of fibre, of different cata1ysts results were:
No resin - 45% brightness;
1~
Example 4 dibutyltin diac.etate 55.5~ brightness;
Example 5 - dibutyltln di ,aurate 56.5~ brigh~ness;
Example 6 - dibutyltin bis (2-ethylhexanoate) (in ethanol~ 58%
brightness.
Example 7 Figure 1 represents the variation in pulp brightness wi~h ~ime in a mill trial, using dibutyltin diacetate catalyst with 1 ton of n~wsprint, at a consistency of 12 to 15~. The lowest curve is a comparative run with no resin added. The middle curve is wi~h 2%
recin and 0.25% catalyst, based on the weight of fibre, ar,d t~e highest curve is with 4b resin and 0.5~ catalyst based on the weight of fibre.
Example 8 Fisure 2 shows the effects of varying temperature on 6 experimen~al runs using 4g resin and 1.5~ by weight dibutyltin diacetate based on the weight of fibre.
Example 9 Figure 3 shows the effect of increasing resin concentration using 1.5~ by weight of dibutyltin diacetate based on the weight of fibre.
Example 10 Example 1 was repeated adding expanded polystyrene beads of from 1 to lOmm. diameter to the dispersed resin precursor immediately prior to the addition of the fibre. The beads were readily separated from the pulp and gave a substantial mprovem,ent in agglomeration and separation of the print~ Optimum results were ~L;~ 3 obtained with 1-2mm~ beadsO The separated beads were rec~cled ~o the pulper and the experiment repeated. The recycled beads provided a substantially eqLIivalent improvement in the agglomeration of the print to that provided by the original uncontaminated beads~
Example 11 Example 1 was repeated. Particles of aggl~merated p int were separated from the pulp and 50~ of the separated particles were recycled to the pulper and the example repeated again. On the second run improved agglomeration and easier separation was observed.
Examples 12 and 13 An acrylic resin precursor was used in the Examples 12 and 13 consisting of wt~ Substance Function Carrier Trade Mark 65 hydroxyethyl- prepolymer 50X in acrylate ~utylacetate "DURASOL" 346 30 hexamethylene-1,6-diisocyanate cross linker xylene "DESMODUR" N75 5 ethylene glycol/
propylene glycol dispersant "GLYCOL B"
hydroxymethyl siloxane copolymer This was compared with the silicone resin precursor of Example 1 as follows:
~.2 ~ 3 Example 12 Furnish 100~ News Catalyst Dibut~ltindilaurate (1~ on fibre addition) Brightness R 457Ex-Dulper 2nfinite wash Caustic only 37 49 3% Acrylate/caustic 45 5i~
2~ Silicone/caustic 47 55 Examp 1 ~ 13 Furnish 50/50 News/magazines Catalyst Dibutyltindilaurate (1~ on fibre addition~
Brightness R 457 Ex-pulper After flotation Caustic only 50 54-~
2~ Acrylate RTV/caustic 52 63 2~ Silicone RTV/caustic 56 62 Example 14 To illustrate the effects of including a non-functional extender in the resin example 1 was repeated adding various proportions of methyl functional polydimethyl siloxane to the reactive prepolymer9 with the following results:-by wt. reactive prepolymer Ex pulper brightness 51.5 51.8 51.
50.0 Comparative (no resin~ 40.7 ~ 3 Example 15 A prepolymer emulsion was prepared comprising:
Dihydroxy poly~dimethyl siloxane) n=49-144 (mean MW = 7566) 109 Dihydroxy poly(d~.methyl siloxane) n= 850 (mean MW = 63066) 409 Poly(methyl hydrosiloxane) n=40 (mean MW = 2562) 459 5~ aqueous solution of polyvinyl alcohol 1659 A catalyst emulsion having 33Z by wt. of solids was prepared separately containing:
dibutyl tin dilaurate 609 polyvinyl alcohol 79 water 133g 1900 ml of wa~er and 69 prepolymer emulsion (lZ resin based on the weight of fibre) were stirred in a pulper with 13 ml concentrated sodium hydroxide solution and 0.3 ml of the catalyst emulsion (0.05% based on the weight of fibre) at room temperature for a 30 second precure period. 2.36 gm of waste newsprint were then added to provide a pulp having a consistency of 11%.
After 25 minutes pulping the pulp was washed and compared with a control run using sodium hydroxide solution only.
Ex pulper brightness Washed brightness Control 3~.5 42.8 Example 15 46.3 51
Claims (26)
1. A composition comprising:
(i) an aqueous, recycled cellulosic fibre pulp;
(ii) dispersed in the pulp, from 0.1% to 10%
based on the weight of the pulp solids of a curable precursor of a non-fibre-substantive solid polymer, the precursor consisting essentially of a mixture of a fluid prepolymer having at least two reactive functional groups per molecule and a cross-linking agent capable of reacting with the functional groups: and (iii) a quantity effective to vulcanize the precursor of a catalyst capable of curing the precursor in the dispersion.
(i) an aqueous, recycled cellulosic fibre pulp;
(ii) dispersed in the pulp, from 0.1% to 10%
based on the weight of the pulp solids of a curable precursor of a non-fibre-substantive solid polymer, the precursor consisting essentially of a mixture of a fluid prepolymer having at least two reactive functional groups per molecule and a cross-linking agent capable of reacting with the functional groups: and (iii) a quantity effective to vulcanize the precursor of a catalyst capable of curing the precursor in the dispersion.
2. A composition according to claim 1, containing a diluent for the precursor mixture, the diluent being an inert, non-fibre-substantive fluid and the precursor mixture and diluent being present in amounts of, respectively, from 10 to 85% by weight and at least 5%
by weight of the dispersed materials.
by weight of the dispersed materials.
3. A composition according to claim 2, containing an effective amount of a dispersant for the precursor mixture.
4. A composition according to any of claims 1, 2 and 3, wherein the resin precursor is curable at a temperature below 50°C.
5. A composition according to any of claims 1, 2 and 3, wherein the resin precursor is curable at room temperature.
6. A composition according to claim 1, wherein the resin precursor comprises a mixture of a dihydroxypoly (dialkyl siloxane; polymer and a poly (alkyl hydrosiloxane) cross-linking agent.
7. A composition according to claim 6, wherein each alkyl group has from 1 to 4 carbon atoms.
8. A composition according to claim 7, wherein the alkyl groups are methyl groups.
9. A composition according to claim 1, wherein the resin precursor comprises a mixture of an oligomeric hydroxy acrylate prepolymer and a diisocyanate cross-linking agent.
10. A composition according to claim 1, wherein the cross-linking agent is present in a proportion of from 1:10 to 10:1 by weight relative to the prepolymer.
11. A composition according to claim 3, wherein the dispersant is a polymeric protective colloid.
12. A composition according to claim 3, wherein the dispersant is present in an amount of from 0.1 to 20% by weight of the resin precursor.
13. A composition according to claim 2, wherein the diluent is present in an amount of from 55 to 80% of the dispersed materials.
14. A composition according to claim 2, wherein the diluent is a polydimethyl siloxane with terminal methyl groups, or a hydrocarbon oil.
15. A composition according to claim 1, wherein the curing catalyst is a dialkyl tin dialkanoate.
16. A composition according to claim 15, wherein the catalyst is a dibutyl tin dialkanoate in which each alkanoate moiety has from 8 to 14 carbon atoms.
17. A composition according to claim 1, wherein the catalyst is present in an amount of from 0.1 to 50%
by weight of the resin precursor.
by weight of the resin precursor.
18. A method of making pulp from recycled cellulosic material contaminated with print, which comprises macerating the material in an aqueous dispersion containing sufficient of a fluid, non-fibre substantive resin precursor curable in the dispersion to facilitate subsequent de-inking, and curing the resin precursor during the maceration.
19. A method according to claim 18, wherein, to an aqueous dispersion comprising a curable precursor of a non-fibre-substantive solid polymer, the precursor consisting essentially of a mixture of a fluid prepolymer having at least two reactive functional groups per molecule and a cross-linking agent capable of reacting with the functional groups, a quantity effective to vulcanize the precursor of a catalyst capable of curing the precursor in the dispersion is added, the dispersion is allowed to precure for up to 20 minutes, and the dispersion is then added to the cellulosic material.
20. A method according to claim 18 or 19, wherein the resin precursor is used in an amount of from 0.1 to 10% based on the weight of pulp solids.
21. A method according to claim 18, wherein the dispersion has a pH of from 8 to 12.5 during the maceration.
22. A method according to claim 18, 19 or 21, wherein the cellulosic material is macerated in pulping liquor for from 10 to 60 minutes at a temperature of from 5 to 60°C at a solids content of from 2 to 25%.
23. A method according to claim 18, 19 or 21, wherein the pulping liquor contains a sequestrant for calcium ions.
24. A method according to claim 18, 19 or 21, wherein the resin precursor contains a blowing agent.
25. A method according to claim 18, 19 or 21, wherein the pulp contains solid particles of polymer.
26. A method of making pulp wherein:
recycled cellulosic material contaminated with print is repulped in a pulper in the presence of a dispersed curable resin, which is non-substantive to the cellulose but substantive to the print, in conditions adapted to effect curing of the resin and agglomeration of the print thereby;
pulp is withdrawn from the pulper;
cured resin is separated from the pulp; and a part of the cured resin is recycled to the pulper.
recycled cellulosic material contaminated with print is repulped in a pulper in the presence of a dispersed curable resin, which is non-substantive to the cellulose but substantive to the print, in conditions adapted to effect curing of the resin and agglomeration of the print thereby;
pulp is withdrawn from the pulper;
cured resin is separated from the pulp; and a part of the cured resin is recycled to the pulper.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8411888A GB8411888D0 (en) | 1984-05-10 | 1984-05-10 | Deinking of recycled cellulosic material |
| GB8411888 | 1984-05-10 | ||
| GB8421546 | 1984-08-24 | ||
| GB848421546A GB8421546D0 (en) | 1984-08-24 | 1984-08-24 | Composition |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249903A true CA1249903A (en) | 1989-02-14 |
Family
ID=26287718
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000480828A Expired CA1249903A (en) | 1984-05-10 | 1985-05-06 | Composition and method of deinking of recycled cellulosic material |
Country Status (13)
| Country | Link |
|---|---|
| US (2) | US4919754A (en) |
| EP (1) | EP0163444B1 (en) |
| KR (1) | KR930002070B1 (en) |
| AU (1) | AU575941B2 (en) |
| BR (1) | BR8502313A (en) |
| CA (1) | CA1249903A (en) |
| DE (1) | DE3567920D1 (en) |
| DK (1) | DK204585A (en) |
| ES (1) | ES8702968A1 (en) |
| FI (1) | FI81134C (en) |
| GB (1) | GB2158836B (en) |
| PL (1) | PL152354B1 (en) |
| YU (1) | YU76185A (en) |
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| US5876559A (en) * | 1991-06-25 | 1999-03-02 | International Paper Company | Deinking of impact and non-impact printed paper by an agglomeration process |
| US5259969A (en) * | 1991-09-16 | 1993-11-09 | International Paper Company | Deinking of impact and non-impact printed paper |
| US5234543A (en) * | 1991-10-03 | 1993-08-10 | International Paper Company | Deinking method using ink agglomeration |
| US5314580A (en) * | 1992-07-08 | 1994-05-24 | Mauvin Material & Chemical Processing Limited | Process for the removal of ink, resin, and adhesive residues from paper, textile fabrics and solid surfaces |
| US5340439A (en) * | 1992-08-06 | 1994-08-23 | International Paper Company | Method for removing ink from printed paper using agglomerating agent, followed by addition of talc |
| US5500082A (en) * | 1993-04-26 | 1996-03-19 | North Carolina State University | Deinking of xerographic printed wastepaper using long chain alcohol |
| US5405495A (en) * | 1993-07-02 | 1995-04-11 | Nalco Chemical Company | Recycling of xerographic waste paper using organic particulates |
| AU677468B2 (en) * | 1994-02-02 | 1997-04-24 | Hercules Incorporated | Felt conditioner for deinked recycled newsprint papermaking systems |
| US6074527A (en) * | 1994-06-29 | 2000-06-13 | Kimberly-Clark Worldwide, Inc. | Production of soft paper products from coarse cellulosic fibers |
| US5582681A (en) * | 1994-06-29 | 1996-12-10 | Kimberly-Clark Corporation | Production of soft paper products from old newspaper |
| US6001218A (en) * | 1994-06-29 | 1999-12-14 | Kimberly-Clark Worldwide, Inc. | Production of soft paper products from old newspaper |
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| US20020062935A1 (en) * | 1995-12-27 | 2002-05-30 | Weyerhaeuser Company | Paper and absorbent products with reduced pitch content |
| US6296736B1 (en) | 1997-10-30 | 2001-10-02 | Kimberly-Clark Worldwide, Inc. | Process for modifying pulp from recycled newspapers |
| US6423183B1 (en) * | 1997-12-24 | 2002-07-23 | Kimberly-Clark Worldwide, Inc. | Paper products and a method for applying a dye to cellulosic fibers |
| US6387210B1 (en) | 1998-09-30 | 2002-05-14 | Kimberly-Clark Worldwide, Inc. | Method of making sanitary paper product from coarse fibers |
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| US6749721B2 (en) | 2000-12-22 | 2004-06-15 | Kimberly-Clark Worldwide, Inc. | Process for incorporating poorly substantive paper modifying agents into a paper sheet via wet end addition |
| US7749356B2 (en) * | 2001-03-07 | 2010-07-06 | Kimberly-Clark Worldwide, Inc. | Method for using water insoluble chemical additives with pulp and products made by said method |
| US6582560B2 (en) | 2001-03-07 | 2003-06-24 | Kimberly-Clark Worldwide, Inc. | Method for using water insoluble chemical additives with pulp and products made by said method |
| GB0217197D0 (en) * | 2002-07-24 | 2002-09-04 | Dow Corning | Method of deinking |
| US6916402B2 (en) | 2002-12-23 | 2005-07-12 | Kimberly-Clark Worldwide, Inc. | Process for bonding chemical additives on to substrates containing cellulosic materials and products thereof |
| US7534322B2 (en) * | 2004-09-29 | 2009-05-19 | International Paper Company | Method of deinking recycled paper employing centrifigal cleaners |
| US7670459B2 (en) | 2004-12-29 | 2010-03-02 | Kimberly-Clark Worldwide, Inc. | Soft and durable tissue products containing a softening agent |
| US20110192558A1 (en) * | 2008-10-17 | 2011-08-11 | Stephenson Group Limited | Recycling of fibre products |
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-
1985
- 1985-05-06 CA CA000480828A patent/CA1249903A/en not_active Expired
- 1985-05-08 YU YU76185A patent/YU76185A/en unknown
- 1985-05-08 DK DK204585A patent/DK204585A/en not_active Application Discontinuation
- 1985-05-09 AU AU42249/85A patent/AU575941B2/en not_active Ceased
- 1985-05-10 GB GB8511885A patent/GB2158836B/en not_active Expired
- 1985-05-10 KR KR1019850003198A patent/KR930002070B1/en not_active IP Right Cessation
- 1985-05-10 EP EP19850303307 patent/EP0163444B1/en not_active Expired
- 1985-05-10 FI FI851860A patent/FI81134C/en not_active IP Right Cessation
- 1985-05-10 PL PL1985253325A patent/PL152354B1/en unknown
- 1985-05-10 BR BR8502313A patent/BR8502313A/en unknown
- 1985-05-10 DE DE8585303307T patent/DE3567920D1/en not_active Expired
- 1985-05-10 ES ES543058A patent/ES8702968A1/en not_active Expired
-
1987
- 1987-03-18 US US07/028,017 patent/US4919754A/en not_active Expired - Fee Related
-
1990
- 1990-01-12 US US07/464,341 patent/US5073234A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DK204585A (en) | 1985-11-11 |
| FI851860A0 (en) | 1985-05-10 |
| ES8702968A1 (en) | 1987-01-16 |
| KR850008198A (en) | 1985-12-13 |
| YU76185A (en) | 1987-12-31 |
| GB2158836A (en) | 1985-11-20 |
| ES543058A0 (en) | 1987-01-16 |
| US4919754A (en) | 1990-04-24 |
| GB2158836B (en) | 1988-03-02 |
| PL152354B1 (en) | 1990-12-31 |
| FI81134C (en) | 1990-09-10 |
| US5073234A (en) | 1991-12-17 |
| BR8502313A (en) | 1986-01-21 |
| AU575941B2 (en) | 1988-08-11 |
| GB8511885D0 (en) | 1985-06-19 |
| DK204585D0 (en) | 1985-05-08 |
| FI851860L (en) | 1985-11-11 |
| EP0163444B1 (en) | 1989-01-25 |
| FI81134B (en) | 1990-05-31 |
| EP0163444A1 (en) | 1985-12-04 |
| AU4224985A (en) | 1985-11-14 |
| PL253325A1 (en) | 1986-02-11 |
| DE3567920D1 (en) | 1989-03-02 |
| KR930002070B1 (en) | 1993-03-26 |
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