GB2048914A

GB2048914A - Printing inks

Info

Publication number: GB2048914A
Application number: GB8013387A
Authority: GB
Original assignee: National Research Development Corp UK; National Research Development Corp of India
Current assignee: National Research Development Corp UK; National Research Development Corp of India
Priority date: 1979-04-23
Filing date: 1980-04-23
Publication date: 1980-12-17
Also published as: EP0027804A1; WO1980002292A1

Abstract

A modified drying or semi-drying oil equivalent for use in the formulation of an alkyd resin system for the ink vehicle of a lithographic printing ink contains within its chemical structure linkages which are readily cleavable under mildly alkaline conditions. In particular the invention includes oil equivalents of formula I R<s1>s-X-(R<s3>sR<s4>s)Y-X-R<u2>u, wherein R<s1>s and R<s2>s comprise unsaturated aliphatic groups, especially ethylenically unsaturated C<u10-24>u aliphatic groups e.g. linoleic residues; X comprises an alkali labile bridging group, preferably a sulphur, an acyloxy, a nitrogen or especially an oxygen bridging group; Y comprises silicon (Si) or titatium (Ti), and R3 and R4 comprise aliphatic, aromatic or araliphatic groups or groups of formula R<s1>s-X- or R<s2>s-X-, wherein R<S1>s, R<s2>s and X are as previously defined. Preferred oil equivalents in which the R-X-substituents are amine or alcohol residues are prepared by ammonolysis or alcoholysis of the corresponding amine or alcohol with a suitable substituted silane or titanate precursor. The oil equivalent is incorporated e.g. from about 5 to about 50% by weight, in alkyd resin systems with typical alkyd polymer chain material, and the alkyd resin systems are blended e.g. up to about 10% by weight, in lithographic printing ink compositions with pigment and diluent. These ink composites advantageously exhibit improved de-inking properties as compared with prior art lithographic inks.

Description

SPECIFICATION Printing inks This invention relates to printing inks, and in particular to lithographic printing inks.

Printing inks typically comprise pigmented material dispersed in a suitable vehicle which acts as a carrier for the ink during printing and may also serve to bind the pigment to the printed substrate. The vehicles used in such printing inks usually comprise polymeric, monomeric or oligomeric material normally together with drying or semi-drying fatty ester material, such as linseed oil. For example, typical ink formulations for sheet-fed and web-fed lithographic printing contain vehicles comprising alkyd resin systems containing drying oils such as linseed oil.

In recent years the demand for paper and board products, coupled with dwindling natural wood fibre resources, has necessitated the recycling of waste paper, but waste paper must be de-inked before it is suitable for use for production of some paper products, such as printing papers, tissue and higher grades of packaging. Customary de-inking processes include either washing or flotation processes in which the ink and pulp material are effectively separated, and in most cases a satisfactory level of deinking is obtained. With some paper-ink systems, however, including sheet-fed and web-fed lithographic printing ink systems, there is considerable resistance to the separation of the ink and pulp material on de-inking.It appears that these inks contain components which become cross-linked by oxidation, to form large three-dimensional ink particles which become entangled with the paper fibre and resist de-inking. This poses a real problem as mixed waste paper feed stocks almost inevitably contain some material printed with such de-inking resistant inks.

In U.K. Patent Application No.41147/78 Serial No.2007691 it is proposed to enhance the de-inking properties of inks, including in particular those which resist de-inking, by providing an ink having an ink vehicle the chemical structure of which includes linkages with are readily cleavable under conditions which are sufficiently different from those of normal ink usage so as to permit printing with the ink in the customary manner, though are not so severe as to cause substantial disruption or damage of paper fibre. Preferred conditions for cleavage are alkaline conditions, especially mildly alkaline conditions, in particular the mildly alkaline conditions which conveniently prevail during the pulping of waste paper. In particular U.K.Patent Application No. 41147/78 Serial No. 2007691 proposes the use of silicon ether linkages as preferred cleavable linkages i.e. linkages of the general formulae -0-Si(R1R2)-O-, SiR(-0-) or Si(-O-)4 wherein R1, R2 and R may be aromatic residues e.g. phetiyl residues, or aliphatic residues preferably alkyl residues, especially lower alkyl residues, e.g. ethyl or methyl residues.

Furthermore, it is proposed to include the preferred silicon ether cleavable linkages within the polymer chain structure e.g. alkyd resin structure, of the ink vehicles used in conventional lithographic printing inks. Incorporation of the preferred silicon ether linkages within the polymer chain structure of the polyester component of lithographic ink vehicles is not completely satisfactory, however, as the polymer structure may tend to stabilise the cleavable linkages. Also, if attempts are made to incorporate the silicon ether linkages into the polyester or alkyd resin polymer chain structure by silylation of free hydroxyl groups before resin preparation, silicon may be lost together with the water which is formed.

Accordingly the present invention comprises a modified drying or semi-drying oil equivalent for use in the formulation of an alkyd resin system-for the ink vehicle of a lithagraphic printing ink, in which the oil equivalent contains within its chemical structure linkages which are readily cleavable under mildly alkaline conditions as hereinafter defined.

The invention also includes an alkyd resin system, for use in the ink vehicle of lithographic printing ink, comprising alkyd polyester material together with an oil equivalent according to the invention.

Furthermore, the invention also includes a lithographic printing ink having an ink vehicle containing an alkyd resin system comprising an oil equivalent according to the invention.

The mildly alkaline conditions for cleavage of the linkages contained within the chemical structure of the oil equivalent are preferably the alkaline conditions which conveniently prevail during the pulping of waste paper and which typically include the presence of small quantities of surface active agents such as a soap or a detergent. Under such mildly alkaline conditions the cleavable linkages are typically significantly more easily cleaved than are the ester linkages contained in the unmodified fatty ester materials which are customarily used in conventional alkyd resin systems e.g. the linoleic ester linkages of linseed oil.Thus, characteristically the cleavable linkages of the modified oil equivalent of the invention cleave under mildly alkaline conditions e.g. pH1 0, at rates which are at least 10 times and preferably at least 100 times faster than the rate at which the linoleic ester linkages of linseed oil cleave under the same conditions. Particularly preferred oil equivalent cleavable linkages are substantially completely alkali labile under the alkaline conditions prevailing during the pulping of waste paper.

Typical alkaline conditions prevailing during the pulping of waste paper are alkaline conditions in the range from about pH8 up to about pH 12.5, especially pH's in the range from about 9 up to about 11.5.

The fatty ester materials which are incorporated in conventional alkyd resin systems are typically esters of fatty acids, usually unsaturated fatty acids, with polyhydric alcohols, such as the tri-substituted linoleic acid ester of glycerol which is the predominant component of linseed oil. The modified oil equivalents of the invention are generally based on such fatty ester materials though typically comprise within their chemical structures linkages which are readily cleavable under mildly alkaline condition, these linkages being present instead of the more stable ester linkages of the fatty ester materials.

Thus in particular, the invention includes a modified drying or semi-drying oil equivalent of formula R'--X-(R3R4)YY--X-R2 I wherein R' and R2 comprise unsaturated aliphatic groups; X comprises an alkali labile bridging group; Y comprises silicon (Si) or titanium (Ti), and R3 and R4 comprise aliphatic, aromatic or araliphatic groups or groups of formula R1-X- or R2-X-, wherein R', R2 and X are as previously defined.

The alkali labile group X may be any suitable group which is labile under mildly alkaline conditions, e.g. pH 10. Such alkali labile groups may include aluminium or phosphorus bridging groups in which the aluminium or phosphorus is linked directly with the central atom Y. Also the alkali labile group may comprise a phosphate ester group in which the phosphorus is linked to the central atom Y via a bridging oxygen atom. Preferred alkali labile groups however, comprise sulphur e.g. R1-S-Y, acyloxy e.g.

R1-CO-Y-, oxygen e.g. R1-0-Y, and nitrogen e.g. R1-NH-Y-, bridging groups, and of these nitrogen and especially oxygen are particularly preferred.

The groups R1 and R2 may comprise ethylenically or acetylenically unsaturated aliphatic or araliphatic groups. Thus R' and R2 may be joined together as a single unsaturated group, preferably an ethylenically unsaturated group, to form a ring structure with the central atom Y, in which case groups R3 and R4 typically comprise groups of formula P1-X or R2--X. More usually, however, the groups R1 and R2 are separate and comprise unsaturated, preferably ethylenically unsaturated, aliphatic groups.

Usually also, the carbon chain lengths of the groups r' and R2 are from C10 to C24, preferably from C10 to C20, or especially from Cie to C18.

Preferred substituents R1-X- and P2-X- comprises primary acyl or primary thioalcohol, or especially primary amine or primary alcohol residues. Thus the substituents R1-X- and R2-X- may comprise C10 to C24, or especially C16 to C18, unsaturated fatty alcohol orfattyamine residues. For example, in particularly preferred embodiments the substituents P1-X- and P2-X- comprise linoleic amine or especially linoleic alcohol residues.

The groups R3 and R4 may comprise aromatic substituents e.g. phenyl groups, but more usually comprise lower aliphatic substituents, normally comprising from 1 to 6 carbon atoms. Thus the substituents R3 and R4 may both comprise cyclopentadiene substituents to provide a compound in which the central atom Y is sandwiched between the cyclopentadiene rings, as in ferrocene. Preferably the substituents R3 and R4 comprises lower alkyl groups, usually comprising from 1 to 4 carbon atoms, e.g. ethyl or methyl groups.

In preferred embodiments the additive or oil equivalent of the ink comprises a silicon ether of formula II or Ill, or a tetra substituted ether of titanium of formula IV (P1-O)3-Si-R3, (R1--0)6Si III (P1-O)4-Ti IV wherein R1 and R3 are as hereinbefore defined.

Oil equivalents of formula I may be produced by any suitable process in which a compound corresponding to a compound of formula I in which the group P1-X- and/or P2-X- is absent is reacted so as to introduce said groups or groups thereto. Preferred oil equivalents according to the invention, having R-X- substituents which are amine or alcohol residues, may be prepared by ammonolysis or alcoholysis of the corresponding amine or alcohol with a suitable substituted silane or titanate precursors. Thus preferred oil equivalent compounds, such as those of formula II, Ill or IV above, may be prepared by alcoholysis of a suitable primary alcohol, especially a C18 to C18 fatty alcohol e.g.

linoleic alcohol with a tri or tetra functional alkoxy silane or titanate. Commercially available fatty alcohols may be used, which typically comprise a mixture of fatty alcohols, e.g. a mixture containing linoleic alcohol.

Alkyd resin systems for use in the inks of the invention are prepared by incorporating the oil equivalent with the typical alkyd polymer chain material. Preferably the oil equivalent is incorporated into the alkyd resin system subsequent to esterification of the alkyd. For instance, a mix containing the alkyd polyester with the oil equivalent is heated, e.g. to a temperature of from about 1 60--2000C. The resultant alkyd resin system is typically a partially cross-linked alkyd resin system in which the oil equivalent characteristically provides the cross-linking between the polyester alkyd units. For instance, the unsaturated groups R1 and R2 interact with unsaturated substituents, e.g. linoleic ester substituents which are attached to the alkyd polymer chains and thereby provide for cross-linking between separate polymer chains. The oil equivalent, however, contains the linkages which are cleavable under mildly alkaline conditions and thereby provides the means by which the cross-linked resin may be broken up under mildly alkaline conditions. It will be appreciated, therefore, that the proportion of cleavable linkages present in the ink vehicle aikyd resin system may be adjusted by varying the amount of oil equivalent incorporated into the alkyd resin system. Usually from about 5 to about 50%, preferably from about 25 to about 40% by weight of oil equivalent is incorporated into the alkyd resin system.

Preferably the silicon content of the alkyd resin system lies in the range from about .1 up to about 5% or especially from about .5 up to 2.5% when considering preferred silicon ether oil equivalents such as those of formulae II and III above. Similar levels of silicon and titanium are expected to be suitable for other cleavable linkages.

The alkyd resin systems of the invention, containing the modified oil equivalent, may be blended in the normal fashion with pigment e.g. carbon black, and diluents, such as mineral oils, to provide new lithographic ink formulations. Usually the resin system is blended into the ink at a level of up to about 10% by weight, preferably at a level of about 5% by weight These inks advantageously exhibit improved de-inking properties as compared with prior art lithographic inks in which the alkyd resin system of the ink vehicle does not contain a modified oil equivalent according to the invention. Generally the offset inks of the present invention are more easily separated from the paper fibre during de-inking processes than are the prior art offset inks.Also, on repuiping prior to de-inking, the average ink particle size of released films of the inks of the present invention is usually substantially smaller than that of corresponding prior art inks, preferably giving rise to speck-free repulped feed stocks.

The invention includes processes for the production of a de-inked paper pulp product in which waste paper comprising paper printed with an ink according to the invention is pulped under mildly alkaline conditions and subjected to de-inking. Both flotation and washing de-inking processes may be used.

The invention is further described by way of illustration only in the following examples.

Example 1 Preparation of modified oil equivalents Silicon and titanium ether oil equivalents are prepared by alcoholysis of the corresponding alcohol with alkoxy substituted silanes or titanates. These silanes and titanates are prepared by interaction of suitable halogen substituted silicon or titanium compounds with the corresponding alcohol. For example, tetra ethoxy silane is prepared by adding tetra chloro silane dropwise to a fourfold molar excess of ethanol containing a molar excess of urea, taking precautions to maintain the temperature below 400 C. The tetra-ethoxy silane product is recovered from the reaction mixture by distillation, the constant boiling point fraction being collected, and is cha!acterised by IR and n.m.r. measurements.

(A) Preparation ofsilicon ether oil equivalents from a commercially available fatty alcohol mixture A range of silicon ether oil equivalents is prepared by alcoholysis of a commercialiy available fatty alcohol mixture (R'OH), Unjecol 90 (supplied by the New Japan Chemical Co. Limited, Osaka Japan) with alkoxy silane precursors. The Unjecol 90 is a mixture of fatty alcohols, having linoleic alcohol as its major component and an lodine value of about 90.

I. Si(OR')4tetra-ethoxy silane (1 mole), as prepared above, is mixed with Unjecol 90 (4 moles) and a catalytic quantity of sodium ethoxide and boiled under reflex for 1 hour. The reaction is then forced to completion by boiling.off the ethanol produced over a period of about 3 hours. The Unjecol 90 substituted product Si(OR')4) is used without further purification.

II. MeSi(OR')3 A monomethyl tri Unjecol 90 substituted silicon ether oil equivalent is prepared similarly by heating trimethoxymethylsilane (1 mole) with Unjecol 90 (3 moles) in the presence of a sodium methoxide catalyst, and forcing the reaction to completion by boiling off the methanol produced. Again the product is used without further purification.

III. Me2SiFOR')2 A dimethyl di-Unjecol 90 substituted silicon ether oil equivalent is similarly prepared by alcoholysis of Unjecol 90 (2 moles) with dimethyldiethoxysilane (1 mole).

(B) Preparation of silicon ether and titanium ether oil equivalents from linoleic alcohol Linoleic alcohol (R-OH) substituted oil equivalents are also prepared by alcoholysis of linoleic alcohol with alkoxy substituted silanes and titanates. The linoleic alcohol used is prepared by reduction of linoleic acid with lithium aluminium hydride.

0.66 moles of lithium aluminium hydride is dissolved in ether and 0.66 moles of linoleic acid is added dropwise to the solution, the temperature being maintained below 400 C. At the completion of this addition the reaction mixture is refluxed for 30 minutes and -100 ml of ether is added to make up losses of ether which have been distilled off. An excess of glacial acetic acid is then added dilutes with 200 ml of water. The ether layer is then separated from the water layer by use of a separating funnel, and the linoleic alcohol product is recovered from the ether fraction by fractional distillation and characterised by IR and lodine value measurements.The IR spectrum shows no absorbance at 1 71 0 cm~1 indicating the absence of linoleic acid in the product, though shows a hydroxyl absorbance band at about 3350 cam~' arising from the linoleic alcohol hydroxyl group. The lodine value of the product is determined by the standard technique (ASTM D 1 959-69) and is found to be 163, as compared with a value of 1 62 found for linoleic acid.

I and II. MeSi(OR)3 andSi(OR)4 Tri-linoleic alcohol substituted methyl silane and tetra-linoleic alcohol substituted silane are prepared by alcoholysis procedures essentially the same as those described above for Unjecol 90 substituted oil equivalents.

III Ti(OR)4 Similarly a tetra-linoleic alcohol substituted titanate oil equivalent is prepared by heating a mixture of tetra-n-butoxy titanate (1 mole) and linoleic alcohol (4 moles) with a sodium ethoxide catalyst under reflux for about 1 hour, after which the reaction is forced to completion by distilling off the n-butyl alcohol product over a period of about 2 2 to 3 hours. The tetra-linoleic alcohol substituted titanic product is used without further purification.

Example 2 Alkyd formulation The oil equivalents prepared above in Example 1 are incorporated with an alkyd resin to provide alkyd resin systems according to the invention.

The alkyd resin is prepared prior to oil equivalent incorporation. Trimethylol propane (2 moles) is mixed with linseed oil (1 mole) and subjected to a slow heat up to about 2000C over a period of several hours to give a product predominantly comprising the monoglyceride, the end point being determined by the methanol clear test. Phthalic anhydride (2 moles) is then added to this product and the mixture heated at about 2500C, heating being continued until the alkyd product is cooked to low acid number i.e. below 10.

1 5 g of each of the oil equivalents (Al-Il and BI-Ill) is mixed with a 37.5 g aliquot of the alkyd resin prepared above and the mixture is heated, under slow heat up conditions, to a temperature of 1 60-2000C over a period of about 2 hours. The silicon contents of the resultant partially cross-linked alkyd resin systems are determined by atomic adsorption measurements and the results obtained are given below in Table TABLE I Oil equivalent Si(OR')4 MeSi(OR')3 Me2Si(OR')2 MeSi(OR)3 Si(OR)4 Ti(OR)4 0.61 1.01 1.32 1.86 0.71 0.05 % SI content Example 3 Inks Inks are prepared by blending the alkyd resin systems prepared in Example 2 into typical ink formulations.Also, for the sake of comparison an ink is also prepared using a conventional linseed oil modified version of the alkyd resin prepared in Example 2. The ink formulations are prepared according to the following recipe.

Carbon black 20 grms Gelling Agent 1 grm H.V. Mineral Oil 55 grms Asphalt varnish 8 grms and Alkyd resin system 4 grms All the inks are found to print satisfactorily by offset iitho on Bowater newsprint and an analysis of the distilled water fount solution of the printing press shows no appreciable silicon content indicating the stability of the inks during normal printing procedures. The de-inking characteristics of the inks are compared by pulping and de-inking of standard sheets printed with the inks, followed by production of hand sheets from the de-inked pulp and comparison of these sheets by reflectance measurements.

Bowater newsprint is printed on both sides with the inks with a selection of type face characters ranging from 8 pt to 60 pt, about half of the paper surface being covered with printing. The sheets are left for about 1 week before de-inking, which is carried out by both washing and flotation de-inking procedures.

The washing procedure employed essentially comprises a low consistency (3%) paper disintegration procedure carried out in a standard pulp disintegrator for 75,000 revolutions, at pH 10, using 0.1% non-ionic detergent. The pulp washing procedure employed consists of a 3 stage wash at consistency changes of 0.06% to 5% per cycle using a 60 mesh screen.

The flotation procedure employed comprises an identical pulping phase except the detergent is omitted and the consistency is 3.5%. Flotation is performed in an 8 1. flotation tank fitted with a stirrer and base bubbler, at pH 10 and at a consistency of 0.88% using 2% soap on fibre. A standard residence time of 20 minutes is adopted.

Separate hand sheets are prepared from the de-inked pulped fibre from each ink for both flotation and washing de-inking and the de-inking characteristics of the inks are compared by reflectance measurements on the hand sheets. The optical reflectance of the hand sheets is measured against a barium sulphate standard at 457 nm using a twin beam Beckmann spectrometer. The general visual appearance of the hand sheets are also noted. The results obtained are given below in Table II, the results relating to the flotation de-inked hand sheets being referenced by the letter f and those relating to the washing de-inked hand sheet being referenced by the letter w. These results clearly show the improved de-inking properties of the oil equivalent modified inks of the invention as compared with conventional linseed oil alkyd inks.

TABLE II Comparison of de-inking properties of oil equivalent modified inks by reflectance measurements of hand- sheets prepared from de-inked pulps.

Ink Type De-inking Reflectance Visual (by oil equivalent procedure at 457 nm appearance component of against a Ba alkyd system) 804 standard Non-modified F 44.6 Grey, slightly conventional specky. linseed oi.l alkyd W 45.0 Brown, slightly specky SI(OR ')4 F -46.9 Grey, specky W 47.2 Grey, slightly specky MeSi(OR 33 F 51.0 Clean W i 47.4 Grey, slightly specky W 47.4 Grey, slightly specky Me2Si(OR)2 F 51.3 Very clean w W 49.0 Clean with few specks MeSi(OR)8 F 49.1 Clean, few ink specks W 46.8 Clean, few ink specks Si(OR)4 F 51.2 Very clean W 47.4 Very clean Ti(OR)4 F 49.4 Very clean W 49.8 Very clean

Claims

1. A modified drying or semi-drying oil equivalent for use in the formulation of an alkyd resin system for the ink vehicle of a lithographic printing ink, in which the modified oil equivalent contains within its chemical structure linkages which are readily cleavable under mildly alkaline conditions as hereinbefore defined.

2. An oil equivalent according to Claim 1, of formula i.

R1-X-(R3R4)Y-X-R2 wherein R1 and R2 comprise unsaturated aliphatic groups; X comprises an alkali labile bridging group; Y comprises silicon (Si) or titanium (Ti) and R3 and R4 comprise hydrocarbon groups or groups of formula R1-X- or R2-X-, wherein R1, R2 and X are as previously defined.

3. An oil equivalent according to Claim 2 in which the alkali labile group comprises a sulphur, an acyloxy, a nitrogen or an oxygen bridging group.

4. An oil equivalent according to Claim 2 or 3, in which the groups R1 and R2 are joined together as a single unsaturated group to form a ring structure with the central atom Y and R3 and R4 comprise groups of formula R1-X- or R2-X-.

5. An oil equivalent according to any of Claims 2-4, in which R1 and R2 comprise ethylenically unsaturated aliphatic groups.

6. An oil equivalent according to any of Claims 2,3 or 5 in which groups R' and R2 are from C,0 to C24 groups.

7. An oil equivalent according to Claim 6, in which R: and R2 comprise Ct8 to C,8 groups.

8. An oil equivalent according to Claim 7, in which the substituents R1-X- and R2-X comprise linoleic amine or linoleic alcohol residues.

9. An oil equivalent according to any of Claims 2-8, in which the groups R3 and R4 comprise C1-C6 lower aliphatic substituents.

10. An oil equivalent according to Claim 9, in which the substituents R3 and R4 comprise cyclopentadiene substituents to provide a compound in which the central atom Y is sandwiched between the cyclopentadiene rings.

11. An oil equivalent according to any of Claims 2-10, of formula 11, III or iV (R1-0)3-Si-R3 (R1-O)4-Si Ill (R1-O)4-Ti IV wherein, R1 and R3 are as hereinbefore defined.

12. A process for the production of an oil equivalent according to Claim 2, in which a compound corresponding to a compound of formula I in which the group R1-X- and/or R2-X- is absent is reacted so as to introduce said group or groups thereto.

13. A process according to Claim 1 2, for production of a compound of formula I in which the R-X subtituents are amine or alcohol residues is prepared by ammonlolysis or alcoholysis of the corresponding amine or alcohol with a suitable substituted silane or titanate precursor.

14. A process according to Claim 1 3,for production or a compound of formula II, III or IV by alcoholysis of a suitable primary alcohol with a tri or tetra functional alkoxy silane or titanate.

15. A process according to Claim 14, in which the alcohol comprises a mixture of fatty alcohols, containing linoleic alcohol.

1 6. An alkyd resin system for incorporation in the ink vehicle of a lithographic printing ink comprising alkyd polyester material together with a modified drying or semi-drying oil equivalent according to any of Claims 111.

1 7. An alkyd resin system according to Claim 16, comprising from about 5 up to about 50% by weight of the oil equivalent

18. An alkyd resin system according to Claim 16, comprising from about 0.1 up to about 5% by weight of silicon or titanium.

1 9. A process for the production of an alkyd resin system according to Claim 16, comprising incorporating the oil equivalent with a typical alkyd polymer chain material.

20. A process according to Claim 19, in which the oil equivalent is incorporated into the alkyd resin system subsequent to esterification of the alkyd.

21. A process according to Claim 20, in which a mix containing the alkyd polyester with the oil equivalent is heated.

22. A lithographic printing ink having an ink vehicle containing an alkyd resin system according to Claim 1 6 together with pigment and diluent.

23. An ink according to Claim 22, comprising up to about 10% by weight of an alkyd resin system according to Claim 1 6.

24. A process for the production of an ink according to Claim 22, comprising blending an alkyd resin system according to Claim 1 6 with pigment and diluent.

25. A process for the production of a de-inked paper pulp product in which waste paper comprising paper printed with an ink according to Claim 22 is pulped under mildly alkaline conditions and subjected to de-inking.

26. A process according to Claim 25, in which the mildly alkaline conditions are alkaline conditions in the range from about pH8 up to about pH 12.5, especially pH's in the range from about 9 up to about 11.5.