CA2206006A1 - A process for removing printing inks from printed wastepaper - Google Patents

Abstract

The invention concerns a method of removing printing inks from printed wastepaper, whereby an additive is added in a metered manner to the process water and the precipitated solids are then removed by flotation and/or filtration. The additive contains one or a plurality of amino and/or ammonium group-containing polymers and/or copolymers, with number average molecular weights of between 2,000 and 1,000,000, and one or a plurality of cellulose derivatives. The deinked wastepaper is distinguished by high brightness whilst the recycled water is very clear.

Description

CA 02206006 1997-0~-26 H 1130 PCT / 22.11.1994 A process for ~ ~ving printing inks from printed wastepaper Field of the Invention This invention relates to a process for removing printing inks from printed wastepaper in the presence of polymers and/or copolymers containing amino and/or ammonium groups with number average molecular weights in 5 the range from 2,000 to 1,000,000 and cellulose deriva-tives and to the use of the polymers containing amino and/or ammonium groups and cellulose derivatives for the removal of printing inks from printed wastepaper.

Prior Art Today, wastepaper is used in large quantities for the product on of, for example, newsprint and sanitary paper. Lightness and color are important quality fea-tures for papers of this type. To achieve this, the 15 printing inks have to be removed from the printed waste-paper. Th:is is normally done by so-called deinking processes. These processes are carried out in standard wastepaper recycling plants provided with additional equipment for removing the detached printing ink ar-20 ticles. Two important process steps in this regard are:

(1) Refining of the wastepaper. By refining is meantthe process of fiberizing the wastepaper. It may be induced, for example, in aqueous medium by application of 25 mechanical energy (stirring). Fiberizing is accompanied by detachment of the printing ink particles. The print-ing ink particles disintegrate into very small particles between 0.1 and 1,000 ~m in size and are present in finely dispersed form. The refining step gives a grey CA 02206006 1997-0~-26 paper stock suspension.

(2) Removal of the detached printing ink particles from the paper stock suspension. This step of the deinking 5 process may be carried out by washing or flotation (cf., for example, Ullm~nns Encyclopadie der Technischen Chemie, 4th Edition, Vol. 17, pages 570-571 (1979)).
The deinking of wastepaper is normally carried out at alkaline pH values in the presence of alkali metal 10 hydroxides, alkali metal silicates, oxidative bleaching agents and surface-active agents at temperatures in the range from 30 to 50~C. The surface-active agents used are mostly anionic and/or nonionic surfactants, for example soaps, ethoxylated fatty alcohols and/or ethoxy-15 lated alkylphenols (cf., for example, Woch~nhl~tt furPapierfabrikation, 17, 646-6~9 (1985)).
The remc,val of water-based printing inks under the usual alkaline deinking conditions has proved to be particularly problematical. In contrast to conventional 20 oil-based printing inks, the binders and dispersant compounds of water-based printing inks can be dissolved or redispersed under the conditions mentioned. The printing ink itself breaks up and disintegrates into very small particles. These particles are additionally 25 stabilized b~ adsorption of the dispersants on the surface of the pigments. These very small colored particles remain on the fibers and cannot be removed under the usual washing and flotation conditions, result-ing in serious grey discoloration of the paper produced 30 from the raw materials.
According to ctp, Centre Technique du Papier, 1st Research Forl~n on Recycling, 29th - 31st October, 1991, the use of carboxymethyl cellulose can reduce the deposi-tion of print-Lng inks, but does not lead to any improve-CA 02206006 1997-0~-26 ~.

ment in color.
In addition to the printing inks mentioned, water-soluble or colloidally dissolved and finely dispersed solids enter the process waters of the paper making 5 process ancl accumulate undesirably therein at constric-tions in the circuit. These solids are, above all, fillers and fine fibers.
On account of the adverse effects of these solids, the water generally has to be cleaned in the case of 10 closed water circuits and at constrictions in the cir-cuit. This is normally done by flocculation, precipita-tion, adsorption and flotation processes or combinations thereof (cf. for example J. Schurz, Wo~nhl~tt fur Papierfabrikation 1990, 3, 109-118). Wash deinking 15 plants normally operate, for example, on the prlnciple of microflotation where the suspended solids and the dis-solved and colloidal substances are flocculated and then floated out from the water (cf., for example, K. Schnab-el, Wo~h~nhl;~tt fur Papierfabrikation, 1990, 6, 233-237).
Typical flocculants in the treatment of process waters in the paper making industry include inorganic and organic flocculants, such as milk of lime, aluminium or iron salt solutions, cationic polymers, such as polyethy-leneimine, cationic starches, polyamidoamine/epichloro-25 hydrin resins and melamine/formaldehyde resins (cf. the above-mentioned article by W. Auhorn and J. Schurz). A
flocculant particularly preferred by experts is poly-diallyl dimethylammonium chloride (cf., for example, R.
Nicke et al., Wochenblatt fur Papierfabrikation 1992, 14, 30 559-564 and the above-mentioned article by J. Schurz).
This compound, which is normally referred to as poly-DADMAC, is a linear molecule which carries a positive charge at the nitrogen atom in each of the recurring structural units. Towards the outside, this positive CA 02206006 1997-0~-26 charge is neutralized by a negatively charged chloride ion. Overal:L, a polyelectrolyte with a very high charge density is thus formed.

Description of the Invention The problem addressed by the present invention was to provide a process for the removal of printing inks from printed wastepaper. More particularly, this process would improve the whiteness of the paper obtained and, 10 optionally, would also remove finely dispersed solids from the process waters to ml~lm; ze soiling of the process water.
It has now been found that a combination of polymers and/or copolymers containing amino groups and/or ammonium 15 groups and cellulose derivatives is particularly suitable for the treatment of circuit waters and wastewaters in paper manufacture.
The present invention relates to a process for the removal of printing inks from printed wastepaper, in 20 which an additive is added to the process water and the solids precipitated are subsequently removed by flotation and/or filtration, the additive containing (1) one or more polymers and/or copolymers containing amino groups and/or ammonium groups with number average 25 molecular weights in the range from 2,000 to 1,000,000 and (2) one or more cellulose derivatives.
In the presence of a combination of polymers con-taining amino groups and/or ammonium groups and cellulose 30 derivatives, printing inks, for example newsprint inks, book printing inks, offset printing inks, magazine gravure printing inks, flexographic printing inks, laser printing inks and/or packaging gravure printing inks, can be removed from printed wastepaper, for example news-CA 02206006 1997-0~-26 papers, magazines, computer paper, journals, brochures, forms, telephone directories and/or catalogs. The wastepapers deinked in the presence of the combination used in accordance with the invention are distinguished 5 by high degrees of whiteness.
At least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights in the range from 5,000 to 500,000 are preferably used, those having number 10 average molecular weights in the range from 10,000 to 200,000 being particularly preferred.
At l easl partly water-sol ubl e means that more than 0.01~ by weight of the polymers and/or copolymers form clear or clc)udy solutions in water at the in-use pH
15 value.
At lea, t partly water-sol ubl e polymers and/or copolyme~s containing amino groups in the context of the invention also include polymers containing pyridine groups, for example polymers based on 2-vinyl pyridine 20 and/or 4-vinyl pyridine.
A partic:ularly preferred group of polymers for the process according to the invention is obtainable by a) polymerization of monomers containing amino groups corresponding to general formula (I):

o R5 R1 - CH == CR2 - C - Z - (CnH2n) - I (I) \~4 in which R1 and R2 each represent a hydrogen atom or a methyl group, R3 and R4 each represent a hydrogen atom 35 or an alkyl group containing 1 to 4 carbon atoms or a piperazine, piperidine or morpholine group and R5 is a linear or branched alkyl radical containing 1 to 22 CA 02206006 1997-0~-26 carbon atoms, with the proviso that the counterion to the ammonium function is a halogen, sulfate, phosphate, borate or organic acid anion or an electron pair, Z is oxygen or NH and n is a number of 2 to 5, 5 or by b) copolymerization of monomers corresponding to formula (I) with bl) mon.omeric unsaturated acids corresponding to general formu.la (II):
o R5 -- CH = CR6 - C - OH (II) in which R5 and R6 each represent a hydrogen atom or a methyl group and/or b2)monomeric unsaturated carboxylic acid esters corresponding to general formula (III):

O
R7 - CH = CR8 - C - O - (CmH2mO)p - R9 (III) in which R7 and R8 each represent a hydrogen atom or 25 a methyl group and R9 is a linear or branched alkyl group containing 1 to 22 carbon atoms, m is a number of 2 to 4 and p is a number of 0 to 18, with the proviso that, where p = 0, the content of unsaturated carboxylic acid esters in the copolymer does not exceed 90% by weight, 30 and/or b3) acrylamides and/or methacrylamides which may be substituted at: the amide nitrogen atoms by linear and/or branched alky] radicals containing 1 to 22 carbon atoms and/or b4) N-~Tinyl pyrrolidone, or by CA 02206006 1997-0~-26 c) reaction of polymers containing carboxyl groups and/
or ester groups which correspond to the general formula -COOR10, where R10 is an alkyl group containing 1 to 8 carbon atoms, and/or an anhydride group -CO-O-CO- with -5 based on the carboxyl, ester and/or latent carboxylgroups present in these polymers -cl) 0 to 1 ec~uivalent of aminoalcohols correspond-ing to general formula (IV):

/
HO - (CxH2xO)y - R11 - N (IV) \Rl3 in which R11 is an alkylene group containing 1 to 8 carbon ato~Ls or an aromatic group, R12 and R13 independently of one another represent alkyl groups containing 1 to 4 carbon atoms or an aromatic group and 20 the substituents R12 and R13 together with the N atom represent a piperazine, piperidine or morpholine group, x is a number of 2 to 4 and y is a number of 0 to 10, C2) 0 to 1 equivalent of diamines corresponding to general formula (V):

NHRl4 - Rl5 _ NRl6Rl7 (V) in whic:h R15 is an alkylene group containing 1 to 8 carbon atoms or an aromatic group, R14 is hydrogen or an 30 alkyl group containing 1 to 4 carbon atoms, R16 and R17 independently of one another represent alkyl groups containing 1 to 4 carbon atoms or R16 and R17 together represent -C~=CH-N=CH-, c3) 0 to 0.5 equivalent of alcohols corresponding 35 to general formula (VI):

CA 02206006 1997-0~-26 HO ~ (CaH2aO) b--R18 (VI) in which R18 is an alkyl group containing 6 to 22 carbon atoms or an aromatic group, a is a number of 2 to 5 4 and b is a number of 0 to 30 and c4) 0 to 0.5 equivalent of amines corresponding to general formula (VII):
NHR19R20 (VII) in which R19 is hydrogen or an alkyl group containing 1 to 4 carbon atoms and R20 is an alkyl group containing 6 to 22 carbon atoms or an aromatic group, with the proviso that the sum. total of the equivalents of components cl) 15 and c2) is not 0.
Suitable aminofunctional monomers corresponding to general for]~lla I are, in particular, those in which R1 is hydrogen, R2 is hydrogen or methyl, R3 and R4 each represent methyl or ethyl, R5 is an electron pair or an 20 alkyl group containing 1 to 4 carbon atoms, with the proviso that the counterion to the ammonium function is a halogen io:n. Examples are dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl methacrylamide, 25 dimethylaminoneopentyl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate and/or meth-acrylamidopropyl dimethylammonium chloride.
Acrylic acid and/or methacrylic acid is/are prefer-ably used as monomeric unsaturated acids corresponding to 30 general formu.la II.
Monomeric unsaturated carboxylic acid esters corre-sponding to general formula III, in which R9 is preferably a linear or branched alkyl group containing 1 to 8 carbon a.toms, are for example ethyl acrylate, methyl 35 methacrylate, butyl acrylate, butyl methacrylate, octyl CA 02206006 l997-0~-26 acrylate ancL/or an adduct of 3 moles of ethylene oxide with butyl acrylate.
In addition, acrylamide, methacrylamide, N-ethyl acrylamide and/or tert.butyl acrylamide is/are suitable 5 for copol~nerization with aminofunctional monomers corresponding to general formula I.
The polymerization or copolymerization of the aminofunctional monomers corresponding to general formula I is carried out by polymerization processes known per se 10 in ac~ueous media optionally containing water-miscible solvents, such as alcohols, for example isopropanol. A
radical-forming substance, for example potassium or ammonium peroxodisulfate, tert.butyl hydroperoxide, azo-bis-(isobutyronitrile), is added in small quantities as 15 initiator. The polymerization or copolymerization of the aminofunctional monomers corresponding to general formula I may be carried out, for example, by simultaneously adding the monomers I and optionally monomers of groups bl) to b4) clropwise to water containing the initiator.
20 sasically, the polymerization temperature is not critical and may vary within wide limits. Temperatures of 60 to 100~C can be optimal according to the initiator used.
Ac~ueous poly~er and/or copolymer solutions with polymer contents of, for example, 10 to 60% by weight are ob-25 tained.
If the polymers and/or copolymers containing aminogroups and/or ammonium groups suitable for use in accord-ance with the invention are produced by esterification or amidation of carboxyfunctional, ester-functional and/or 30 anhydride-functional polymers with aminoalcohols, di-amines or amines, the following observations apply:
The carboxyfunctional, ester-functional and/or anhydride-functional polymers may be produced by known polymerization processes in organic solvents, such as CA 02206006 l997-0~-26 H 1130 PCT lO

hexane, octane, toluene, xylene and/or ketones. Suitable monomers are, for example, acrylic acid, methacrylic acid, crotonic acid, C1_8 alkyl esters of the above-mentioned acids, aryl esters of the above-mentioned 5 acids, maleic anhydride, maleic acid, fumaric acid, mono-C1_8-alkyl est:ers of the above-mentioned acids, di-C18-alkyl esters of the above-mentioned acids and the corre-sponding aryl esters. The alkyl group of the alcohol radicals in the esters may be linear, branched or cyclic.
A monomer or a mixture of monomers may be used. Acrylic acid, methacrylic acid, acrylates and/or methacrylates are preferably used as monomers. Styrene, alkyl sty-renes, 4-vinyl pyridine, N-vinyl pyrrolidone, acrylo-nitrile, acrylamide, methacrylamide, vinyl chloride 15 and/or vinylidene chloride may be used as further mono-mers. The polymerizations are carried out in the pres-ence of radic,~l-forming substances as described above.
The reaction of the carboxyfunctional, ester-func-tional and/or anhydride-functional polymers with amino-20 alcohols and/or diamines and optionally alcohols and/oramines is carried out with or without organic solvents, preferably in the presence of catalysts, such as sulfuric acid, p-toluene sulfonic acid, dibutyl tin dilaurate, tin and/or alkali metal alcoholates, at temperatures in the 25 range from 100 to 230~C. The water formed during the esterification and/or amidation reaction and/or the alcohols formed are removed by distillation. Suitable organic solvents are, for example, aliphatic and/or aromatic hydrocarbons with boiling points above 100~C.
Suitable aminoalcohols cl) corresponding to general formula IV are, for example, 2-dimethylaminoethanol, 2-diethylaminoethanol, 3-dimethylamino-2,2-dimethyl-1-propanol, 4-(dimethylamino)-1-butanol, 6-(dimethylamino)-1-hexanol, 2-[(2-dimethylamino)-ethoxy]-ethanol, 2-di-CA 02206006 1997-0~-26 butylaminoethanol, 3-dimethylamino-1-propanol, 3-diethyl-amino-1-propanol, 4-dimethylaminophenol, 3-diethylamino-phenol, N-hyclroxyethyl-N-methyl aniline, N-hydroxyethyl-N-ethyl aniline and/or 4-(2-hydroxyethyl)-morpholine.
Examples of diamines c2) corresponding to general formula V are~ N,N-dimethylaminopropylamine, N,N-diethyl-aminopropylamine, N,N-diethylaminoethylamine, 1-diethyl-amino-4-aminopentane, N,N-dimethyl-p-phenylenediamine, N,N-diethyl-p-phenylenediamine and/or 1-(3-aminopropyl)-10 imidazole.
The reactions of carboxyfunctional, ester-functional and/or anhydride-functional polymers with aminoalcohols and/or diamines may be carried out in the presence of alcohols c3) corresponding to general formula VI and/or 15 amines c4) corresponding to general formula VII. The alkyl g~oups present in the alcohols and/or amines may be linear, branched and/or cyclic. Examples of alcohols corresponding to general formula VI are cyclohexanol, 2-ethylhexanol, octanol, decanol, dodecanol, tetradecanol, 20 hexadecanol, octadecanol, docosanol, an adduct of 12 moles of ethylene oxide with tallow alcohol and also benzyl alcohol. Examples of amines corresponding to general formula VII are hexylamine, 2-ethylhexylamine, octylamine, clecylamine, dodecylamine, tetradecylamine, 25 hexadecylamine, octadecylamine, docosylamine, cocoamine and tallow amine.
Another particularly preferred group of polymers for the process according to the invention are polyethylene-imines and/or copolymers containing ethyleneimine. They 30 may optionally be used together with other at least partly water-soluble polymers and/or copolymers contain-ing amino groups and/or ammonium groups with number average molecular weights in the range from 2,000 to 500,000.

CA 02206006 1997-0~-26 In addition, polymers and/or copolymers based on 2-vinyl pyridine, 4-vinyl pyridine and/or 1-vinyl imida-zole, for example poly-4-vinyl pyridine, copolymers of 1-vinyl imidazole and N-vinyl pyrrolidone with vinyl 5 imidazole contents of 10 to 90~ by weight, optionally in combination with other at least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights in the range from 2,000 to 500,000, are also particularly 10 suitable for deinking wastepaper. The production of these polymers and/or copolymers is carried out by polymerization processes known per se, for example in bulk in th.e presence of radical-forming substances (Ullm~nn.s EnGyclopadie der te~,hni schen Chemie, 4th 15 Edition, Vol. 23, pages 611-614, Verlag Chemie Weinheim, 1983).
Primary, secondary, tertiary and/or quaternary aminofunctional polysaccharides and/or heteropolysac-charides and/or derivatives thereof, which may optionally 20 be used in combination with other at least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecu-lar weights of 2,000 to 500,000, are another particularly preferred group of polymers for the deinking process 25 according to the invention. At least partly water-soluble pri.mary, secondary, tertiary and/or quaternary aminofunctior-al celluloses, hydroxyethyl celluloses, starches, chitosan and/or guar are examples of primary, secondary, _ertiary and/or quaternary aminofunctional 30 polysacchar:ides and/or heteropolysaccharides. The introduction of tertiary and/or quaternary amino groups into polysaccharides and/or heteropolysaccharides free from amino groups is carried out in known manner by reacting polysaccharides and/or heteropolysaccharides CA 02206006 1997-0~-26 with tertiary amines containing a glycidyl group and/or with ammonium compounds (US 3,472,840). Dimethyl gly-cidylamine amine and 3-chloro-2-hydroxypropyl trimethyl-ammonium chloride are examples of tertiary amines and 5 ammonium compounds.
In addition, water-dilutable printing inks can be removed particularly effectively from wastepaper in the presence of proteins, optionally in combination with other at least partly water-soluble polymers and/or 10 copolymers containing amino groups and/or ammonium groups with number average molecular weights in the range from 2,000 to 500,000.
In one preferred embodiment of the present inven-tion, the polymers mentioned are used in a cluantity of 15 0.05 to 1% by weight of active substance, based on the paper used.
Cellulose derivatives suitable for use in the process according to the invention are, in particular, the cellulose ethers such as, for example, carboxymethyl 20 cellulose, methyl cellulose, hydroxyalkyl cellulose, and mixed ethers, such as methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, methyl carboxymethyl cellulose and mixtures thereof, carboxymethyl cellulose (Na salt), methyl cellulose and methyl hydroxyethyl 25 cellulose being preferred. The cellulose derivatives are preferably used in quantities of 0.01 to 2.5% by weight and preferably in quantities of 0.02 to 1~ by weight of active substance, based on the paper used.
In many cases, the degree of removal of printing 30 inks can be further increased if the components used in the process according to the invention are combined with flotation collectors and/or inorganic adsorbents or flocculants.
Examples of flotation collectors are C10_22 fatty CA 02206006 1997-0~-26 acids and alkali metal or alkaline earth metal salts thereof, alkoxylated C6_22 alkyl alcohols or alkoxylated alkylphenols, other cationic polymers such as, for example, pclydimethylaminoethyl methacrylate and/or 5 copolymers of the type described, for example, in DE 38 39 479. The fatty acids mentioned and also fatty alcohol alkoxylates with a high percentage content of alkylene oxide, more particularly ethylene oxide, are most par-ticularly suitable. Examples of flocculants are milk of 10 lime, aluminium or iron salt solutions. These components may be used in a quantity of 0.05 to 1% by weight, based on the air-dry paper stock.
The printing inks may be removed from wastepaper, for example, by the following method: in a pulper, 15 printed wastepaper is size-reduced at temperatures of 20 to 60~C and at a stock consistency of, for example, 0.5 to 5% by weight in an aqueous solution typically contain-ing 0 to 1.5% by weight of hydrogen peroxide (100%), 0 to 2.5% by weight of sodium hydroxide (99% by weight), 0 to 20 4.0% by weight of soda waterglass with a solids content of 35% by weight, 0.02 to 2% by weight of the polymers containing amino groups and/or ammonium groups defined above and 0.01 to 1.5% by weight of cellulose derivatives and 0 to 1% by weight of the above-mentioned optional 25 constituents (all percentages by weight based on air-dry wastepaper). After a residence time of typically 60 to 120 minutes at temperatures of 20 to 60~C, more water is stirred into or added to the paper stock suspensions so that 0.6 to 1.6% by weight paper stock suspensions are 30 obtained. The detached printing ink particles are then separated from the paper stock suspensions in known manner by washing or flotation. Flotation is preferably carried out in known manner, for example in a Denver flotation cell (laboratory scale).

f CA 02206006 1997-0~-26 If water-based flexographic printing inks are to be removed from wastepaper, it is advisable to modify the process to lhe extent that the cellulose derivative is actually added in the pulper at a fiber concentration of 5 around 4% by weight and the above-defined polymer con-taining amino groups and/or ammonium groups is added immediately before flotation.
By using a cellulose derivative in combination with a polymer containing amino and/or ammonium groups in 10 accordance with the invention, printing inks can be more easily removed both from wastepaper and from the circuit water. However, the compounds to be used in accordance with the invention may also be used for the separate purification of paper circuit waters, i.e. wastewaters 15 still contalning certain quantities of printing inks. In these cases, the printing ink particles are separated, for example by filtration or flotation, after the addi-tion of 0.5 to 300 mg of the components per liter of circuit water.
The following Examples are intended to illustrate the invention without limiting it in any way.

E x a m p l e s 25 1. Removal of printing inks from alkaline medium 1.1 Refinir~Sr An aqueous suspension of 17.5 g of air-dry, shredded wastepaper ~50% Stern, 15% Rheinische Post, 15% Express, 20~ Flexo 1 6/90) with a consistency of 4% by weight was 30 introduced into a stirred vessel. After a) 2.0% by weight of soda waterglass with a solids content of 35% by weight (37 to 40~Bé), b) 1.0~ by weight of sodium hydroxide (99~ by weight), CA 02206006 1997-0~-26 c) 0.7~ by weight of hydrogen peroxide (100~) and d) 0.2% by weight of a cellulose derivative (cf. Table 1) 5 had been successively added to this suspension (all percentages by weight based on air-dry paper stock), the suspended paper shreds were size-reduced for 10 minutes at 45~C us:ing a dissolver disk (Pendraulik Type 34 laboratory mixer). The paper stock obtained in this way 10 was left standing for 105 minutes at 45~C.

1.2 Printing ink flotation (~i nki ng) The paper stock obtained in accordance with 1.1 was diluted with water (hardness 16~dH) to a consistency of 15 1% by weight. 0.2% by weight, based on the paper used, of a polymer containing amino groups and/or ammonium groups (cf. I'able 1) in the form of an aqueous solution was then added. The paper stock was floated in a Denver laboratory flotation cell for 12 minutes at 45~C at a 20 speed of 1000 r.p.m. After flotation, the paper stock obtained was separated from water on a filter nutsche, formed into a sheet between two filter papers in a photo dry press and dried for 90 minutes at 100~C.

25 2. Test results Particulars of the tests described under 1. are set out in Table 1 below. It can be seen from Table 1 that excellent results are obtained in the process according to the invention both in regard to the whiteness of the 30 stock and in regard to the color of the circuit water (measured as ~ransmission).

Table 1 t ¦Example IPolymer ¦Cellulose der. ¦Whiteness ¦Water ~ 1% Refl. 1%
Transm.¦

¦ ~-1 ¦ A I _ ¦ 51-9 ¦ 93 .-1 A Clllmin~l~ MHPC 55.9 96 ~1 1 1 1 1 .~-2 A Culminalt~ MC 53.1 96 -CA 02206006 1997-0~-26 Copolymer of 73% by weight of dimethylaminoethyl methacrylate, 11~ by weight of acrylic acid and 16%
by weight of methyl methacrylate Methyl hydroxypropyl cellulose (a product of Aqualon) Methyl cellulose (a product of Aqualon) Example C-1 is intended for comparison while Examples E-1 and E-2 correspond to the invention Color o:f the circuit water (expressed in %
transmission) Cellulo,e derivative used (0.1% by weight) Whitene.,s of the deinked paper (expressed in %
reflectance ) Polymer used (0.2% by weight)

Claims (13)

1. A process for the removal of printing inks from printed wastepaper, in which an additive is added to the process water and the solids precipitated are subsequently removed by flotation and/or filtration, characterized in that the additive contains (1) one or more polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights in the range from 2,000 to 1,000,000 and (2) one or more cellulose derivatives.

2. A process as claimed in claim 1, characterized in that the polymers and/or copolymers containing amino groups and/or ammonium groups have number average molecular weights of 5,000 to 500,000 and preferably in the range from 10,000 to 200,000.

3. A process as claimed in claim 1 or 2, characterized in that polymers containing amino groups and ammonium groups obtainable by a) polymerization of monomers containing amino groups corresponding to general formula (I):

(I) in which R1 and R2 each represent a hydrogen atom or a methyl group, R3 and R4 each represent a hydrogen atom or an alkyl group containing 1 to 4 carbon atoms or a piperazine, piperidine or morpholine group and R5 is a linear or branched alkyl radical containing 1 to 22 carbon atoms, with the proviso that the counterion to the ammonium function is a halogen, sulfate, phosphate, borate or organic acid anion or an electron pair, Z is oxygen or NH and n is a number of 2 to 5, or by b) copolymerization of monomers corresponding to formula (I) with b1) monomeric unsaturated acids corresponding to general formula (II):

(II) in which R5 and R6 each represent a hydrogen atom or a methyl group and/or b2) monomeric unsaturated carboxylic acid esters corresponding to general formula (III):

(III) in which R7 and R8 each represent a hydrogen atom or a methyl group and R9 is a linear or branched alkyl group containing 1 to 22 carbon atoms, m is a number of 2 to 4 and p is a number of 0 to 18, with the proviso that, where p = 0, the content of unsaturated carboxylic acid esters in the copolymer does not exceed 90% by weight, and/or b3) acrylamides and/or methacrylamides which may be substituted at the amide nitrogen atoms by linear and/or branched alkyl radicals containing 1 to 22 carbon atoms and/or b4) N-vinyl pyrrolidone, or by c) reaction of polymers containing carboxyl groups and/or ester groups which correspond to the general formula -COOR10, where R10 is an alkyl group containing 1 to 8 carbon atoms, and/or an anhydride group -CO-O-CO- with -based on the carboxyl, ester and/or latent carboxyl groups present in these polymers -c1) 0 to 1 equivalent of aminoalcohols corresponding to general formula (IV):

(IV) in which R11 is an alkylene group containing 1 to 8 carbon atoms or an aromatic group, R12 and R13 independently of one another represent alkyl groups containing 1 to 4 carbon atoms or an aromatic group and the substituents R12 and R13 together with the N atom represent a piperazine, piperidine or morpholine group, x is a number of 2 to 4 and y is a number of 0 to 10, C2) 0 to 1 equivalent of diamines corresponding to general formula (V):

NHR14 - R15 - NR16R17 (V) in which R15 is an alkylene group containing 1 to 8 carbon atoms or an aromatic group, R14 is hydrogen or an alkyl group containing 1 to 4 carbon atoms, R16 and R17 independently of one another represent alkyl groups containing 1 to 4 carbon atoms or R16 and R17 together represent -CH=CH-N=CH-, c3) 0 to 0.5 equivalent of alcohols corresponding to general formula (VI):

HO - (CaH2aO)b-R18 (IV) in which R10 is an alkyl group containing 6 to 22 carbon atoms or an aromatic group, a is a number of 2 to 4 and b is a number of 0 to 30 and c4) 0 to 0.5 equivalent of amines corresponding to general formula (VII):
NHR19R20 (VII) in which R19 is hydrogen or an alkyl group containing 1 to 4 carbon atoms and R20 is an alkyl group containing 6 to 22 carbon atoms or an aromatic group, with the proviso that the sum total of the equivalents of components c1) and c2) is not 0, are used.

4. A process as claimed in claim 1 or 2, characterized in that polymers and/or copolymers containing amino groups and/or ammonium groups, polyethyleneimines and/or copolymers containing ethyleneimine are used, optionally in combination with other at least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights of 2,000 to 1,000,000.

5. A process as claimed in claims 1 or 2, characterized in that polymers based on 2-vinyl pyridine, 4-vinyl pyridine and/or 1-vinyl imidazole, optionally in combination with other at least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights of 2,000 to 1,000,000, are used as the polymers and/or copolymers containing amino groups and/or ammonium groups.

6. A process as claimed in claim 1 or 2, characterized in that primary, secondary, tertiary and/or quaternary polysaccharides and/or heteropolysaccharides containing ammonium groups, optionally in combination with other at least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights of 2,000 to 1,000,000, are used as the polymers and/or copolymers containing amino groups and/or ammonium groups.

7. A process as claimed in claim 1 or 2, characterized in that proteins, optionally in combination with other at least partly water-soluble polymers and/or copolymers containing amino groups and/or ammonium groups with number average molecular weights of 2,000 to 1,000,000, are used as the polymers and/or copolymers containing amino groups and/or ammonium groups.

8. A process as claimed in claims 1 to 7, characterized in that cellulose ethers, such as carboxymethyl cellulose, methyl cellulose, hydroxyalkyl cellulose, and mixed ethers, such as methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, methyl carboxymethyl cellulose and mixtures thereof are used as the cellulose derivatives.

9. A process as claimed in any of claims 1 to 8, characterized in that the cellulose derivatives are used in a quantity of 0.01 to 2.5% by weight of active substance, based on air-dry paper used.

10. A process as claimed in any of claims 1 to 9, characterized in that the polymers and/or copolymers containing amino groups and/or ammonium groups are used in a quantity of 0.02 to 5% by weight of active substance, based on air-dry paper used.

11. A process as claimed in any of claims 1 to 10, characterized in that the cellulose derivatives are added during the refining step while the polymer and/or copolymer containing amino groups and/or ammonium groups is/are added immediately before flotation.

12. A process as claimed in any of claims 1 to 11, characterized in that components 1) and 2) are used in combination with a flotation collector and/or an inorganic flocculant.

13. A process as claimed in any of claims 1 to 12, characterized in that the solids separated by flocculation are removed by flotation.