Title of Invention	METHOD OF DEINKING
Abstract	A method of deinking printed paper, the method comprising pulping the paper by disintegrating it k>y mechanical agitation in an aqueous medium, to form an aqueous slurry, adding a deinking additive to the paper, and removing detached ink by flotation through the blowing of air bubbles into the pulp, wherein the additive comprises an organo-modified siloxane comprising units of the formula: in which each R' is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group; each Z is independently selected from n is an integer greater than 1; a and b are independently 0, 1, 2 or 3; R2 is an alkylene group or a direct bond; R3 is a group as defined for R1 or Z above; p and r are independently an integer from 1 to 6; q and s are independently 0 or an integer such that 1 < q + s < 400; and wherein each molecule of the organo-modified siloxane contains at least one group Z.

Title of Invention

METHOD OF DEINKING

Abstract

A method of deinking printed paper, the method comprising pulping the paper by disintegrating it k>y mechanical agitation in an aqueous medium, to form an aqueous slurry, adding a deinking additive to the paper, and removing detached ink by flotation through the blowing of air bubbles into the pulp, wherein the additive comprises an organo-modified siloxane comprising units of the formula: in which each R' is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group; each Z is independently selected from n is an integer greater than 1; a and b are independently 0, 1, 2 or 3; R2 is an alkylene group or a direct bond; R3 is a group as defined for R1 or Z above; p and r are independently an integer from 1 to 6; q and s are independently 0 or an integer such that 1 < q + s < 400; and wherein each molecule of the organo-modified siloxane contains at least one group Z.

Full Text	FORM - 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE Specification (See section 10 and rule 13) METHOD OF DEINKING (a) DOW CORNING CORPORATION, U.S.Company of Midland, Michigan 48611, USA; and (b) NOPCO PAPER TECHNOLOGY HOLDING AS, GRANTED 08-05-2008 Norway Company of Graaterudvein 19, N-3036, Drammen, Norway THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:- ORIGINAL The present invention relates to a method of deinking printed wastepaper. Growing awareness of environmental damage caused by deforestation has seen an increase in the recycling of wastepaper in'recent ye#ars. it has been recognised that the ability to recycle wastepaper is commercially advantageous and has a significant impact on the conservation of virgin fibre resources. However, technological advances in printing inks and print media.present ever-growing challenges to recyclers. Printing on paper is typically accomplished using one of two types of ink, namely, impact ink, which is physically pressed onto the paper, and non-impact ink, which is attracted to a charged image and is then transferred to the paper. Impact inks are typically wet inks, for example letterpress inks, offset litho inks, photogravure inks and flexographic inks. For example, letterpress inks are generally composed of carbon black pigment in a mineral oil vehicle and are used in, for example, newspaper printing. Offset litho inks tend to contain more pigment than letterpress inks and contain drying oils such "as linseed" or alkyl resins. Flexographic inks are used in similar processes to letterpress inks but are water-based and contain emulsified ink in an alkali soluble binder. Such inks may easily be dislodged, but may form extremely fine particles that are difficult to capture and remove. Non-impact inks, e.g. toners, are generally dry, powdered inks end are used in laser printing, photocopying 'and facsimile machines and generally comprise thermoplastic-resir.s and pigment. The deinking of paper bearing these two different types of ink requires different deinking procedures and conditions. Conventionally, deinking of paper bearing non-impact ink merely requires pulping with a surfactant in neutral conditions, whereas paper bearing impact ink requires different conditions, such as treatment with alkali, silicate and peroxide, as well as a surfactant. In conventional deinking methods, the wastepaper is disintegrated (pulped.) by mechanical agitation in an aqueous medium to separate the ink and impurities from the paper fibre and disintegrate the ink into particles of approximately 0.1 to 1000 um. A grey slurry is thus obtained in which the ink is present in a finely dispersed form. The impurities, for example, plastic, aluminium foil, stones, screws, staples, paper clips etc., are removed during a large number of screening steps. Whilst ink detachment of non-impact, e.g. photocopy, paper can normally be achieved in neutral conditions, for other printed paper ink detachment is routinely accomplished at alkaline pH levels using alkali hydroxides, alkali silicates, oxidative-working bleaches and surfactants at temperatures between 30 and 50°C. Usually, anionic and nonionic tensides are used as surfactants, for example, soaps, ethoxylated fatty alcohols and/or ethoxylated alkyl phenols (see, for example, 2F 0013758). The ink particles are then removed from, the fibre slurrv by washing and/or flotation. Smaller ink particles are removed by washing, and larger ink particles and stickic-s (i.e. glue residues and adhesives) are removed by flotation, ing flotation, air babbles are blown into the pulp. The dispersed ink particles become attached to the air bubbles, which carry the ink particles to the surface. The resultant involve heating the pulp to evenly distribute stubborn ink particles and screening the' pulp to separate the damaged, short or weak fibres. The remaining clean pulp is then pressed between rollers into sheets and dried. Thus, efficient deinking demands both successful separation of the ink from the paper fibre and removal of the dispersed ink from the fibre slurry. However, there are a number of disadvantages associated with traditional deinking methods. For example, the incomplete removal of ink particles from the fibre slurry can cause the resulting paper to have a grey hue, spotting, and a low degree of brightness. Brightness and colour are important quality criteria for many paper uses. In addition, the alkaline conditions used in traditional deinking methods cause water-soluble and/or colloidal solids and finely dispersed solids to contaminate the process water, for example, fillers, fine fibres and stickies. If these contaminants are insufficiently removed during washing, they can be concentrated by subsequent washings and reintroduced to the paper fibre, causing a loss of brightness in the resultant paper. Effluent containing the aforementioned chemicals conventionally used in deinking methods is also environmentally undesirable. The present invention seeks to provide a method of deinking wastepaper which can overcome disadvantages of conventional deinking methods. A method of deinking printed paper, the method comprising pulping the paper by disintegrating it by mechanical agitation in an aqueous medium, to form an aqueous slurry, adding a deinking additive to the paper, and removing detached ink by flotation through the blowing of air bubbles into the pulp, wherein the additive comprises an organo-modified siloxane comprising units of the formula: In which each R1 is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group; each Z IS independently selected from n is an integer greater than 1; a and b are independently 0, 1, 2 or 3; R2 is an alkylene group or a direct bond; R3 is a group as defined for R1 or Z above; p and r are independently an integer from 1 to 6; q and s are independently 0 or an integer such that 1 and wherein each molecule of the organo-modified siloxane contains at least one group Z. Z is a group preferably wherein p and/or r are independently 2, 3 or 4, i.e. a group comprising ethylene, propylene, and/or butylene oxide groups. Preferably, q and s are each independently integers from 10 to 30, more preferably 15 to 25 (for example 18). In a particularly preferred group Z, p is 2, r is 3, and q and s are both 18. R2 may be an alkylene group, for example having from 1 to 6 carbon atoms (i.e.a methylene, ethylene propylene, butylene, pentylene or hexylene group), or a direct bond. R3may be a group as defined hereinabove for R1 or Z, and is preferably a hydrogen atom or a hydroxyl group. The siloxane may be linear or may comprise units in which a +b =0 or 1, i.e. the siloxane may contain branching. When Z is a group R3 is preferably a >hydroxy1 or alkanoyloxy group. Preferably, 2 to 20 mole percent of silicon atoms in the siloxane molecule are substituted by a group Z, more preferably 5 to 16 mole percent. The siloxane preferably has a hydrophilic/lipophilic balance (HLB)in the range of 5.0 to 7.3. The molecular weight of the siloxane is preferably in the range of 1,000 to 500,000, more preferably 10,000 to 100,000. A particularly preferred siloxane for use in the present invention is a hydroxy-endcapped linear polydimethylsiloxane having an HLB of 5.9 to 6.3, in which 10 to 12 mole percent of silicon atoms are substituted by Z groups of the formula in which p is 2, r is 3 and q and s are both 18, R2 is an alkylene group having from 1 to 6 carbon atoms or a direct bond, and R3 is a hydrogen atom or a hydroxy!, ester or ether group. Tne additive used in the present invention may comprise further components, in addition to the organo-modified siloxane. For example, the additive may further comprise one or more components selected from a polydimethylsiloxane, an organic polyether, and a fatty acid. Suitable organic polyethers include those of the formula in which R in the method of the present invention, the additive may be added to the paper before, during or after pulping. The amount of additive to be added to the paper is preferably within the range 0.1 to 1 wt% of the paper, more preferably 0.1 to 0.5 wt%. The additive may, for example, be added to the paper neat, as an emulsion, or in solution, for example an aqueous solution. The method of the present invention is preferably performed at substantially neutral pH, although the method may be performed under alkaline pH. The pulping and ink removal steps of the present invention may be performed as is conventional, as will be familiar to a person skilled in the art and described hereinabove. For example, the paper may be pulped to form an aqueous slurry having a consistency of, for example, from 1 to 10% (for example, 1 to 5%) at a temperature of between 30 and 50°C, for example 35 to 45°C. Consistency is defined as wt% of pulp solids in the fibre suspension. Ink removal may be performed in a suitable flotation cell (for example, a Denver Lab flotation cell) at a suitable temperature, for example between 30 and 50°C (e.g. 35 to 45°C), and number of revolutions per minute, for example fron 500 to 1000 rpm. An additional advantage associated with the method of the present invention is that when used to treat flexographic printed waste, the process water is relatively clear, whereas with known deinking methods it is generally black. Moveover, the present method-produces pulp of improved brightness. Embodiments of the present invention will now be described in detail. Example 1 a) Bulping To an aqueous suspension of 110 g of air-dry wastepaper (50% newspaper and 50% magazine paper) having a consistency of 4% were added 440g of industrial water at 45°C in'a mixing vessel. The suspended paper was kneaded for 15 minutes at 45°C. b) Ink removal Water having a hardness of 16°dH was added to the pulp obtained in a) above to achieve a consistency of 1%. To-the pulp varying -amounts of a hydroxyl endcapped polydimethylsiloxane having approximately 11 mole % silicon atom substitution by side chains, an KLB of approximately 6.1 and a molecular, weight of approximately 60,000 (referred to herein as Siloxane 1) was added as an aqueous solution. The pulp was floated for 8 minutes at 45°C in a Denver Lab Flotation Cell at 1000 rpm, after which the pulp was separated from the water, and formed into sheets between two filters of a sheet former with drying at 95°C for 10 rainu.tes under vacuum. By way of comparison, steps a) and b) above were repeated using a commercially available fatty acid based deinking preparation. The results are shown in Table 1 below. Whiteness was evaluated according to DIN 53145 Part 1. Example 2 a) Pulping To an aqueous suspension of 11Og of air-dry wastepaper (10% newspaper and 90% magazine paper) having a consistency of 20% were added 440ml of industrial water at 45°C in a mixing vessel. The suspended paper was kneaded for 15 minutes at 45°C. b) Ink removal Water was added to the pulp obtained in a) above to achieve a consistency of 1.09%. To the pulp varying amounts of a hydroxyl endcapped siloxane as defined in Table 4 below were added as an aqueous solution. The pulp was floated for 8 minutes at 45°C in.a Denver Lab Flotation Cell. Steps a) and b) above were repeated using the siloxane used in Example 1 (Siloxane 1) and the s'iloxanes defined in Table 4 (Siloxanes 2 to 8) on fresh and aged wastepaper. Table 4 also contains viscosity data for each of the siloxanes. By way of comparison, the experiment was also carried out using the commercially available fatty acid based deinking preparation used in Example 1. The results are shown in Table 2 (fresh wastepaper) and Table 3 (aged wastepaper) below. Whiteness was evaluated according to DIN 53145 Part Example 3 a) Pulping To an aqueous suspension of HOg of air-dry wastepaper (100% newspaper), having a consistency of 20% were added 400ml of industrial water at 45°C in a mixing vessel. The suspended paper was kneaded for 15 minutes at 45°C. b) Ink removal Water was added to the pulp obtained in a) above to achieve a consistency of 1.09%. To the pulp varying amounts of a hydroxy! endcapped siloxane as defined in Table 4 and Example 1 were added as an aqueous solution. The pulp was floated for 8 minutes at 45°C in a Denver Lab Flotation Cell. Steps a) and b) above were repeated using the siloxane used in Example 1 (Siloxane 1) and two of the siloxanes defined in Table 4 (Siloxanes 4 and 7) . By way of comparison, the experiment was also carried out using the commercially available fatty acid based deinking preparation used in Example 1. The results are shown in Table 5 below. Whiteness was evaluated according to DIN 53145 Part 1. Example 4 Steps a) and b) of Example 1 were repeated using the siloxane used in Example 1 (Siloxane 1), but were performed on 100% flexographic paper. In addition, 0.10 wt% sodium hydroxide and 1.20 wt% sodium silicate were added to the slurry. By way of comparison, the experiment was also carried out using the commercially available fatty acid based deinking preparation used in Example 1. The results are shown in Table 6 below. The appearance of the filtration water vzs also recorded. Whiteness was evaluated according to DIN 53145 Part 1. We Claim: 1. A method of deinking printed paper, the method comprising pulping the paper by disintegrating it k>y mechanical agitation in an aqueous medium, to form an aqueous slurry, adding a deinking additive to the paper, and removing detached ink by flotation through the blowing of air bubbles into the pulp, wherein the additive comprises an organo-modified siloxane comprising units of the formula: in which each R' is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group; each Z is independently selected from n is an integer greater than 1; a and b are independently 0, 1, 2 or 3; R2 is an alkylene group or a direct bond; R3 is a group as defined for R1 or Z above; p and r are independently an integer from 1 to 6; q and s are independently 0 or an integer such that 1 and wherein each molecule of the organo-modified siloxane contains at least one group Z. 2. A method as claimed in claim 1 wherein p and/or r are independently 2, 3 or 4. 3. A method as claimed in claim 1 or 2 wherein q and s are each independently integers from 10 to 30. 4. A method as claimed in claim 3 wherein q and s are each independently 15 to 25. 5. A method as claimed in anyone of claims 1 to 4 wherein p is 2, r is 3, and q and s are both 18. 6. A method as claimed in any preceding claim wherein R2 is a methylene, ethylene, propylene, butylene, pentylene or hexylene group. 7. A method as claimed in any preceding claim wherein R3is a hydrogen atom or a hydroxyl group. 8. A method as claimed in any preceding claim wherein the siloxane is linear. 9. A method as claimed in any preceding claim wherein the siloxane contains branching. 10. A method as claimed in any preceding claim wherein Z is a group -R2- (0CpH2p)q (OCrH2r) s-R3, and R3 is a hydroxyl or alkanoyloxy group. 11. A method as claimed in any preceding claim wherein 2 to 20 mole percent of silicon atoms in the siloxane molecule are substituted by a group Z. 12. A method as claimed in claim 11 wherein 5 to 16 mole percent of silicon atoms in the siloxane molecule are substituted, by a group Z . 13. A method as claimed in any preceding claim wherein the siloxane has a hydrophilic/lipophilic balance (HLB)in the range of 5.0 to 7.3. 14. A method as claimed in any preceding claim wherein the siloxane has a molecular weight in the range of 1,000 to 500,000. 15. A method as claimed in claim 14 wherein the siloxane has a molecular weight in the range of 10,000 to 100,000. 16. A method as claimed in any preceding claim wherein the siloxane is a hydroxy-endcapped linear polydimethylsiloxane having an HLB of 5.9 to 6.3, in which 10 to 12 mole percent of silicon atoms are substituted by Z groups of the formula -R2- (OCpH2p) q (OCrH2r) s-R3, in which p is 2, r is 3 and q and s are both 18, R is an alkylene group having from 1 to 6 carbon atoms or a direct bond, and R3 is a hydrogen atom or a hydroxyl, ester or ether group. 17. A method as claimed in any preceding claim wherein the additive further comprises one or more components selected from a polydimethylsiloxane, an organic polyether, and a fatty acid. 18. A method as claimed in claim 17 wherein the additive further comprises an organic polyether of the formula R4- (0CpH2p) q (OCrH2r) s-R5 In which R4 and R5 are selected from a hydrogen atom, hydroxyl, alkyl and alkoxy groups, p and r are independently an integer from 1 to 6, and q and s are independently 0 or an integer such that 1 — 19. A method as claimed in claim 17 or 18 wherein the additive further comprises a fatty acid which is a saturated or unsaturated monobasic aliphatic carboxylic acid. 20. A method as claimed in claim 19 wherein the carboxylic acid is selected from lauric, myristic, 10 palmitic, stearic, arachidic, behenic, lignoceric, palmitolic, oleic, linoleic, linolenic, and arachidonic acids. 21. A method as claimed in any preceding claim wherein the additive is an emulsion. 22. A method as claimed in claim 21 wherein the additive is a gum based self-emulsifying siloxane. 23. A method as claimed in any preceding 20 claim wherein the additive is added to the paper In an amount within the range 0.1 to 1 wt% of the paper. 24. A method as claimed in claim 23 wherein the additive is added to the paper in an amount within the 25 range 0.1 to 0.5 wt% of the paper. 25. A method as claimed in any preceding claim which is performed at substantially neutral pH. 26. A method substantially as described in the Examples as far as they relate to the use of Siloxanes 1 to 8. Dated this 18th day of January, 2005. MOHAN DEWAN OF R. K. DEWAN & COMPANY APPLICANTS'PATENT ATTORNEY

Full Text

FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See section 10 and rule 13)
METHOD OF DEINKING

(a) DOW CORNING CORPORATION,
U.S.Company of Midland, Michigan 48611, USA; and (b) NOPCO PAPER TECHNOLOGY HOLDING AS,
GRANTED
08-05-2008
Norway Company of Graaterudvein 19, N-3036, Drammen, Norway
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:- ORIGINAL

The present invention relates to a method of deinking
printed wastepaper.
Growing awareness of environmental damage caused by deforestation has seen an increase in the recycling of wastepaper in'recent ye#ars. it has been recognised that the ability to recycle wastepaper is commercially advantageous and has a significant impact on the conservation of virgin fibre resources. However, technological advances in printing inks and print media.present ever-growing challenges to recyclers. Printing on paper is typically accomplished using one of two types of ink, namely, impact ink, which is physically pressed onto the paper, and non-impact ink, which is attracted to a charged image and is then transferred to the paper. Impact inks are typically wet inks, for example letterpress inks, offset litho inks, photogravure inks and flexographic inks. For example, letterpress inks are generally composed of carbon black pigment in a mineral oil vehicle and are used in, for example, newspaper printing. Offset litho inks tend to contain more pigment than letterpress inks and contain drying oils such "as linseed" or alkyl resins. Flexographic inks are used in similar processes to letterpress inks but are water-based and contain emulsified ink in an alkali soluble binder. Such inks may easily be dislodged, but may form extremely fine particles that are difficult to capture and remove.
Non-impact inks, e.g. toners, are generally dry, powdered inks end are used in laser printing, photocopying 'and facsimile machines and generally comprise thermoplastic-resir.s
and pigment.
The deinking of paper bearing these two different types of ink requires different deinking procedures and conditions.

Conventionally, deinking of paper bearing non-impact ink merely requires pulping with a surfactant in neutral conditions, whereas paper bearing impact ink requires different conditions, such as treatment with alkali, silicate and peroxide, as well as a surfactant.
In conventional deinking methods, the wastepaper is disintegrated (pulped.) by mechanical agitation in an aqueous medium to separate the ink and impurities from the paper fibre and disintegrate the ink into particles of approximately 0.1 to 1000 um. A grey slurry is thus obtained in which the ink is present in a finely dispersed form. The impurities, for example, plastic, aluminium foil, stones, screws, staples, paper clips etc., are removed during a large number of screening steps.
Whilst ink detachment of non-impact, e.g. photocopy, paper can normally be achieved in neutral conditions, for other printed paper ink detachment is routinely accomplished at alkaline pH levels using alkali hydroxides, alkali silicates, oxidative-working bleaches and surfactants at temperatures between 30 and 50°C. Usually, anionic and nonionic tensides are used as surfactants, for example, soaps, ethoxylated fatty alcohols and/or ethoxylated alkyl phenols (see, for example, 2F 0013758).
The ink particles are then removed from, the fibre slurrv by washing and/or flotation. Smaller ink particles are removed by washing, and larger ink particles and stickic-s (i.e. glue residues and adhesives) are removed by flotation, ing flotation, air babbles are blown into the pulp. The dispersed ink particles become attached to the air bubbles, which carry the ink particles to the surface. The resultant

involve heating the pulp to evenly distribute stubborn ink particles and screening the' pulp to separate the damaged,
short or weak fibres. The remaining clean pulp is then pressed between rollers into sheets and dried.
Thus, efficient deinking demands both successful separation of the ink from the paper fibre and removal of the dispersed ink from the fibre slurry.
However, there are a number of disadvantages associated with traditional deinking methods. For example, the incomplete removal of ink particles from the fibre slurry can cause the resulting paper to have a grey hue, spotting, and a low degree of brightness. Brightness and colour are important quality criteria for many paper uses.
In addition, the alkaline conditions used in traditional deinking methods cause water-soluble and/or colloidal solids and finely dispersed solids to contaminate the process water, for example, fillers, fine fibres and stickies. If these contaminants are insufficiently removed during washing, they can be concentrated by subsequent washings and reintroduced to the paper fibre, causing a loss of brightness in the resultant paper. Effluent containing the aforementioned chemicals conventionally used in deinking methods is also environmentally undesirable.
The present invention seeks to provide a method of deinking wastepaper which can overcome disadvantages of conventional deinking methods.
A method of deinking printed paper, the method comprising pulping the paper by disintegrating it by mechanical agitation in an aqueous medium, to form an aqueous slurry, adding a deinking additive to the paper, and removing detached ink by flotation through the blowing of air bubbles into the pulp, wherein the additive comprises an organo-modified siloxane comprising units of the formula:

In which each R1 is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group; each Z IS independently selected from

n is an integer greater than 1;
a and b are independently 0, 1, 2 or 3;
R2 is an alkylene group or a direct bond;
R3 is a group as defined for R1 or Z above;
p and r are independently an integer from 1 to 6;
q and s are independently 0 or an integer such that 1 and wherein each molecule of the organo-modified siloxane contains at least one group Z.
Z is a group preferably wherein p and/or
r are independently 2, 3 or 4, i.e. a group comprising ethylene, propylene, and/or butylene oxide groups. Preferably, q and s are each independently integers from 10 to 30, more preferably 15 to 25 (for example 18). In a particularly preferred group Z, p is 2, r is 3, and q and s are both 18. R2 may be an alkylene group, for example having from 1 to 6 carbon atoms (i.e.a methylene, ethylene propylene, butylene, pentylene or hexylene group), or a direct bond. R3may be a group as defined hereinabove for R1 or Z, and is preferably a hydrogen atom or a hydroxyl group.
The siloxane may be linear or may comprise units in which a +b =0 or 1, i.e. the siloxane may contain branching. When

Z is a group R3 is preferably a
>hydroxy1 or alkanoyloxy group.
Preferably, 2 to 20 mole percent of silicon atoms in the siloxane molecule are substituted by a group Z, more preferably 5 to 16 mole percent.
The siloxane preferably has a hydrophilic/lipophilic balance (HLB)in the range of 5.0 to 7.3.
The molecular weight of the siloxane is preferably in the range of 1,000 to 500,000, more preferably 10,000 to 100,000. A particularly preferred siloxane for use in the present invention is a hydroxy-endcapped linear polydimethylsiloxane having an HLB of 5.9 to 6.3, in which 10 to 12 mole percent of silicon atoms are substituted by Z groups of the formula
in which p is 2, r is 3 and q and s are both 18, R2 is an alkylene group having from 1 to 6 carbon atoms or a direct bond, and R3 is a hydrogen atom or a hydroxy!, ester or ether group.
Tne additive used in the present invention may comprise further components, in addition to the organo-modified siloxane. For example, the additive may further comprise one or more components selected from a polydimethylsiloxane, an organic polyether, and a fatty acid. Suitable organic polyethers include those of the formula
in which R
in the method of the present invention, the additive may be added to the paper before, during or after pulping. The amount of additive to be added to the paper is preferably within the range 0.1 to 1 wt% of the paper, more preferably 0.1 to 0.5 wt%. The additive may, for example, be added to the paper neat, as an emulsion, or in solution, for example an aqueous solution.
The method of the present invention is preferably performed at substantially neutral pH, although the method may be performed under alkaline pH.
The pulping and ink removal steps of the present
invention may be performed as is conventional, as will be
familiar to a person skilled in the art and described
hereinabove. For example, the paper may be pulped to form an
aqueous slurry having a consistency of, for example, from 1
to 10% (for example, 1 to 5%) at a temperature of between 30
and 50°C, for example 35 to 45°C. Consistency is defined as
wt% of pulp solids in the fibre suspension. Ink removal may
be performed in a suitable flotation cell (for example, a
Denver Lab flotation cell) at a suitable temperature, for
example between 30 and 50°C (e.g. 35 to 45°C), and number of
revolutions per minute, for example fron 500 to 1000 rpm. An
additional advantage associated with the method of the present
invention is that when used to treat flexographic printed
waste, the process water is relatively clear, whereas with
known deinking methods it is generally black. Moveover, the
present method-produces pulp of improved brightness.
Embodiments of the present invention will now be described in detail.
Example 1 a) Bulping
To an aqueous suspension of 110 g of air-dry wastepaper

(50% newspaper and 50% magazine paper) having a consistency of 4% were added 440g of industrial water at 45°C in'a mixing vessel. The suspended paper was kneaded for 15 minutes at

45°C.
b) Ink removal
Water having a hardness of 16°dH was added to the pulp
obtained in a) above to achieve a consistency of 1%. To-the
pulp varying -amounts of a hydroxyl endcapped
polydimethylsiloxane having approximately 11 mole % silicon
atom substitution by side chains, an KLB of
approximately 6.1 and a molecular, weight of approximately
60,000 (referred to herein as Siloxane 1) was added as an
aqueous solution. The pulp was floated for 8 minutes at 45°C
in a Denver Lab Flotation Cell at 1000 rpm, after which the
pulp was separated from the water, and formed into sheets
between two filters of a sheet former with drying at 95°C for
10 rainu.tes under vacuum.
By way of comparison, steps a) and b) above were repeated
using a commercially available fatty acid based deinking
preparation. The results are shown in Table 1 below.
Whiteness was evaluated according to DIN 53145 Part 1.

Example 2 a) Pulping
To an aqueous suspension of 11Og of air-dry wastepaper
(10% newspaper and 90% magazine paper) having a consistency
of 20% were added 440ml of industrial water at 45°C in a
mixing vessel. The suspended paper was kneaded for 15 minutes
at 45°C.
b) Ink removal
Water was added to the pulp obtained in a) above to achieve a consistency of 1.09%. To the pulp varying amounts of a hydroxyl endcapped siloxane as defined in Table 4 below were added as an aqueous solution. The pulp was floated for 8 minutes at 45°C in.a Denver Lab Flotation Cell.
Steps a) and b) above were repeated using the siloxane used in Example 1 (Siloxane 1) and the s'iloxanes defined in Table 4 (Siloxanes 2 to 8) on fresh and aged wastepaper. Table 4 also contains viscosity data for each of the siloxanes. By way of comparison, the experiment was also carried out using the commercially available fatty acid based deinking preparation used in Example 1. The results are shown in Table 2 (fresh wastepaper) and Table 3 (aged wastepaper) below. Whiteness was evaluated according to DIN 53145 Part

Example 3
a) Pulping
To an aqueous suspension of HOg of air-dry wastepaper (100% newspaper), having a consistency of 20% were added 400ml of industrial water at 45°C in a mixing vessel. The suspended paper was kneaded for 15 minutes at 45°C.
b) Ink removal
Water was added to the pulp obtained in a) above to achieve a consistency of 1.09%. To the pulp varying amounts of a hydroxy! endcapped siloxane as defined in Table 4 and Example 1 were added as an aqueous solution. The pulp was floated for 8 minutes at 45°C in a Denver Lab Flotation Cell.
Steps a) and b) above were repeated using the siloxane used in Example 1 (Siloxane 1) and two of the siloxanes defined in Table 4 (Siloxanes 4 and 7) . By way of comparison, the experiment was also carried out using the commercially available fatty acid based deinking preparation used in Example 1. The results are shown in Table 5 below. Whiteness was evaluated according to DIN 53145 Part 1.
Example 4
Steps a) and b) of Example 1 were repeated using the siloxane used in Example 1 (Siloxane 1), but were performed on 100% flexographic paper. In addition, 0.10 wt% sodium hydroxide and 1.20 wt% sodium silicate were added to the slurry.
By way of comparison, the experiment was also carried out using the commercially available fatty acid based deinking preparation used in Example 1. The results are shown in Table 6 below. The appearance of the filtration water vzs also recorded. Whiteness was evaluated according to DIN 53145 Part 1.

We Claim:
1. A method of deinking printed paper, the method comprising
pulping the paper by disintegrating it k>y
mechanical agitation in an aqueous medium, to
form an aqueous slurry, adding a deinking additive to the paper,
and removing detached ink by flotation through the
blowing of air bubbles into the pulp, wherein the
additive comprises an organo-modified siloxane comprising units
of the formula:
in which each R' is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group;
each Z is independently selected from

n is an integer greater than 1; a and b are independently 0, 1, 2 or 3; R2 is an alkylene group or a direct bond; R3 is a group as defined for R1 or Z above; p and r are independently an integer from 1 to 6; q and s are independently 0 or an integer such that 1 and wherein each molecule of the organo-modified siloxane contains at least one group Z.
2. A method as claimed in claim 1 wherein p and/or r are
independently 2, 3 or 4.

3. A method as claimed in claim 1 or 2 wherein q and s are each
independently integers from 10 to 30.
4. A method as claimed in claim 3 wherein q and s are each
independently 15 to 25.
5. A method as claimed in anyone of claims 1 to 4 wherein p is 2, r is 3, and q and s are both 18.
6. A method as claimed in any preceding claim wherein R2 is a methylene, ethylene, propylene, butylene, pentylene or hexylene group.
7. A method as claimed in any preceding claim wherein R3is a hydrogen atom or a hydroxyl group.
8. A method as claimed in any preceding claim wherein the siloxane is linear.
9. A method as claimed in any preceding claim wherein the siloxane contains branching.
10. A method as claimed in any preceding claim wherein Z is a
group -R2- (0CpH2p)q (OCrH2r) s-R3, and R3 is a hydroxyl or alkanoyloxy
group.
11. A method as claimed in any preceding claim wherein 2 to 20 mole percent of silicon atoms in the siloxane molecule are substituted by a group Z.
12. A method as claimed in claim 11 wherein 5 to 16 mole percent of silicon atoms in the siloxane molecule are substituted, by a group Z .

13. A method as claimed in any preceding claim wherein the siloxane has a hydrophilic/lipophilic balance (HLB)in the range of 5.0 to 7.3.
14. A method as claimed in any preceding claim wherein the siloxane has a molecular weight in the range of 1,000 to 500,000.
15. A method as claimed in claim 14 wherein the siloxane has a molecular weight in the range of 10,000 to 100,000.
16. A method as claimed in any preceding claim wherein the siloxane is a hydroxy-endcapped linear polydimethylsiloxane having an HLB of 5.9 to 6.3, in which 10 to 12 mole percent of silicon atoms are substituted by Z groups of the formula
-R2- (OCpH2p) q (OCrH2r) s-R3, in which p is 2, r is 3 and q and s are both
18, R is an alkylene group having from 1 to 6 carbon atoms or
a direct bond, and R3 is a hydrogen atom or a hydroxyl, ester or
ether group.
17. A method as claimed in any preceding claim wherein the additive further comprises one or more components selected from a polydimethylsiloxane, an organic polyether, and a fatty acid.
18. A method as claimed in claim 17 wherein the additive further comprises an organic polyether of the formula
R4- (0CpH2p) q (OCrH2r) s-R5 In which R4 and R5 are selected from a hydrogen atom, hydroxyl, alkyl and alkoxy groups, p and r are independently an integer from 1 to 6, and q and s are

independently 0 or an integer such that 1 — 19. A method as claimed in claim 17 or 18 wherein the additive further comprises a fatty acid which is a saturated or unsaturated monobasic aliphatic carboxylic acid.
20. A method as claimed in claim 19 wherein the carboxylic acid is selected from lauric, myristic, 10 palmitic, stearic, arachidic, behenic, lignoceric, palmitolic, oleic, linoleic, linolenic, and arachidonic acids.
21. A method as claimed in any preceding claim wherein the additive is an emulsion.
22. A method as claimed in claim 21 wherein the additive is a gum based self-emulsifying siloxane.
23. A method as claimed in any preceding 20 claim wherein the additive is added to the paper In an amount within the range 0.1 to 1 wt% of the paper.
24. A method as claimed in claim 23 wherein the additive is
added to the paper in an amount within the 25 range 0.1 to 0.5
wt% of the paper.
25. A method as claimed in any preceding claim which is
performed at substantially neutral pH.

26. A method substantially as described in the Examples as far
as they relate to the use of Siloxanes 1 to 8.
Dated this 18th day of January, 2005.
MOHAN DEWAN OF R. K. DEWAN & COMPANY APPLICANTS'PATENT ATTORNEY

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Patent Number

224118

Indian Patent Application Number

88/MUMNP/2005

PG Journal Number

06/2009

Publication Date

06-Feb-2009

Grant Date

29-Sep-2008

Date of Filing

18-Jan-2005

Name of Patentee

DOW CORNING CORPORATION

Applicant Address

MIDLAND, MICHIGAN 48611, USA.

Inventors:

#	Inventor's Name	Inventor's Address
1	NELLESSEN BERNHARD	ALMA-MAHLER-WERFEL-STRASSE 4, 41564 KAARST, GERMANY.
2	NORTHFLEET, CHRISTINA	6 MONTAGNE AU CHAUDRON, B-1150 BRUSSELS, BELGIUM.

PCT International Classification Number

D21C5/02 D21H17/13

PCT International Application Number

PCT/EP2003/008166

PCT International Filing date

2003-07-22

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	0217197.3	2002-07-24	U.K.