WO1998050474A1

WO1998050474A1 - Use of colourless polycyclic sulphonates

Info

Publication number: WO1998050474A1
Application number: PCT/GB1998/000861
Authority: WO
Inventors: Dean Thetford; John David Schofield
Original assignee: Avecia Limited
Priority date: 1997-05-01
Filing date: 1998-03-20
Publication date: 1998-11-12
Also published as: AU6739098A; GB9708814D0; ZA983619B

Abstract

The use of a polycyclic aromatic ring system containing 3 or more fused rings, such as pyrene-1-sulphonic acid, for improving the dispersion and/or floculation resistance of a particulate solid in a polar liquid medium.

Description

USE OF COLOURLESS POLYCYCLIC SULPHONATES

This invention relates to the use of a sulphonated aromatic ring system containing 3 or more fused rings (hereinafter SARS) for improving the flocculation resistance of pigments in millbases, paints and printing inks and for generally improving the loading of particulate solids in dispersions. It has already been proposed to incorporate quaternary ammonium salts of copper phthalocyanines (hereinafter CuPc) in millbases, paints and printing inks as fluidising agent to improve the resistance of the formulated pigments to flocculation during the preparation of the paint or printing ink and also to increase the amount of pigment in the dispersion, millbase, paint or ink. However, since the quaternary ammonium salt of the CuPc is intensely coloured the use of such agents is restricted to blue, green and black paints and inks. Fluidising agents of this type are described in GB 1 ,508,576.

Similarly, the sodium salt of sulphonated CuPc has also been proposed as a fluidising agent in water-based systems as disclosed in GB 1 ,596,281. Again, the intense colour restricts its use. It has also been proposed to incorporate quaternary ammonium salts of disazo yellow pigments in millbases, paints and printing inks for similar reasons. Again, because of the colour of these salts they tend to be used only in yellow, orange and red millbases, paints and inks. Fluidising agents of this type are described in EP 76,024.

Fluidising agents for improving flocculation resistance which are colourless or only slightly coloured would be advantageous since they could then be used in millbases, paints and inks covering a wide shade gamut and especially pale shades, particularly those white bases containing titanium dioxide with a small amount of tinter pigment. Colourless or only slightly coloured fluidising agents would also be advantageous in non- colour applications where a particulate solid is dispersed in a liquid medium, especially at high loadings.

Fluidising agents also find a use in all applications involving the dispersion of a particulate solid in a liquid medium and enable a high concentration of the particulate solid to be dispersed in the medium without an adverse increase in viscosity.

According to the invention, there is provided the use of a sulphonated aromatic ring system containing 3 or more fused rings as a fluidising agent for improving the dispersion and/or flocculation resistance of a particulate solid in a polar liquid medium.

Preferably, the SARS contains not greater than 10, more preferably not greater than 8 and especially not greater than 6 fused rings.

The fused rings may contain 5, 6 or 7 atoms and may be carbocyclic or heterocyclic.

Examples of heterocyclic rings are pyridyl and thienyl. Preferably, the SARS contains either 3 or 4 fused rings. It is preferred that the fused rings are all phenyl as in anthracene, phenanthrene and pyrene. Anthraquinone is considered to be a SARS containing fused phenyl rings.

Apart from the sulphonic acid group or groups, the SARS may carry further substituents which are preferably not chromophoric or auxochromic in nature. Examples of such substituents are halogen, alkoxy, alkyl, hydroxy, carboxy, sulphonamide, carbonamide, nitrile, carbonyl and phenoxy. Halogen means fluorine, iodine and particularly bromine and chlorine. When the substituent is alkyl or alkoxy it is preferably C,_₄-alkyl or C^-alkoxy.

It is especially preferred that the SARS is unsubstituted. The SARS may carry more than one sulphonic acid group but it is especially preferred that only the one sulphonic acid group is present. The sulphonic acid is preferably located in the 1 , 2 or 3 position of the SARS.

Particularly useful results have been obtained when the SARS is pyrene-1- sulphonic acid or anthracene-1 -sulphonic acid. Other examples of SARS are anthracene- 2-sulphonic acid, anthraquinone-1 -sulphonic acid and anthraquinone-2-sulphonic acid.

The sulphonic acid group or groups of the SARS may be present in the form of its free acid or it may be present as the alkali metal salt, ammonium salt or as the quaternary ammonium salt. Preferred alkali metals are lithium, potassium and especially sodium. The ammonium salt may be in the form of a primary, secondary or tertiary amine salt. The amine or quaternary ammonium cation preferably contains at least one alkyl group which contains up to 24 carbon atoms. When the amine or quaternary ammonium cation contains three or more alkyl groups which are the same, the number of carbon atoms in each alkyl group is preferably less than 18, more preferably less than 12 and especially less than 10. When the quaternary ammonium group contains one or two alkyl groups containing more than 10 carbon atoms, it preferably contains two C₁_₄-lower alkyl groups, such as methyl.

Particularly useful results have been obtained when the SARS is present as the sodium salt in aqueous-based systems and as the free acid in non-aqueous based systems. As disclosed hereinbefore the SARS is used as a fluidising agent for improving the flocculation resistance and/or fluidity of a particulate solid in a polar liquid medium and especially the flocculation resistance of a pigment in a millbase, paint or printing ink.

The particulate solid may be any material which it is desired to stabilise in a finely divided form in the polar liquid medium. The solid may be inorganic or preferably organic, coloured or non-coloured including pigments and dyestuffs which are substantially insoluble in the liquid medium. Examples of inorganic solids are extenders and fillers such as talc, kaolin, silica, barytes and chalk; particulate ceramic materials such as alumina, silica, zirconia, titania, silicone nitride, boron nitride, silicon carbide, boron carbide, mixed silicon-aluminium nitrides and metal titanates; particulate magnetic materials such as magnetic oxides of transition metals, especially iron and chromium e.g. gamma -Fe₂0₃, Fe₃0₄ and cobalt-doped iron oxides, calcium oxide, ferhtes, especially barium ferhtes; and metal particles, especially metallic iron, nickel, cobalt and alloys thereof, agrochemicals and pharmaceutical solids. Preferably, the particulate solid is a pigment.

The pigment may be from any of the recognised classes of pigments described, for example, in the Third Edition of the Colour Index (1971) and subsequent revisions of, and supplements thereto, under the chapter headed "Pigments". The pigment may be inorganic, metallic, a metal salt of an organic dyestuff (sometimes referred to as a lake or toner) or an organic pigment.

Examples of inorganic pigments are titanium dioxide (including Anatase and Rutile forms, and high UV absorbing ultrafine titanium dioxide), zinc oxide, Prussian Blue, cadmium sulphide, iron oxides (including transparent iron oxides), ultramarine, mica (including pearlescent pigments made by surface treating mica with, for example, fine titanium dioxide) and the chrome pigments, including chromates, molybdates, and mixed chromates and sulphates of lead, zinc, barium, calcium and mixtures and modifications thereof which are commercially available as greenish-yellow to red pigments under the names primrose, lemon, middle, orange, scarlet and red chromes.

Examples of metallic pigments are aluminium flake, copper powder and copper flake.

Examples of metal salts of organic dyestuffs are the azo metal salt pigments such as Cl Pigment Red 48 (also known as 2B Toner or Permanent Red 2B), Cl Pigment Red 53 (also known as Lake Red C or Red Lake C), Cl Pigment Red 52, Cl Pigment Red 57 (also known as 4B Toner, Lithol Rubine, Rubine Toner or Permanent Red 4B), Cl Pigment Red 58, Cl Pigment Red 247, Cl Pigment Yellow 61 , Cl Pigment Yellow 62, Cl Pigment Yellow 183 and Cl Pigment Yellow 191.

Examples of preferred organic pigments are those from the azo, disazo, condensed azo, thioindigo, indanthrone, isoindanthrone, anthanthrone, anthraquinone, isobenzanthrone, triphendioxazine, quinacridone and phthalocyanine series, especially copper phthalocyanine and its nuclear halogenated derivatives, and also lakes of acid, basic and mordant dyes. Carbon black, although strictly inorganic, behaves more like an organic pigment in its dispersing properties. Preferred organic pigments are phthalocyanines, especially copper phthalocyanines, mono azos, disazos, indanthrones, anthanthrones, quinacridones and carbon blacks. Preferably, the pigment is an organic tinter pigment. A tinter pigment is a coloured pigment which is added to a pale-coloured and especially a white base paint, ink or millbase containing a white pigment such as titanium dioxide.

The particulate solid is dispersed in a polar liquid medium which is preferably water or a polar organic liquid including mixtures thereof. By the term "polar" in relation to the medium is meant an organic liquid or resin capable of forming moderate to strong bonds as described in the article entitled "A Three Dimensional Approach to Solubility" by Crowley et al in Journal of Paint Technology, Vol. 38, 1966, at page 269. Such organic liquids generally have a hydrogen bonding number of 5 or more as defined in the aforementioned article.

Examples of polar organic liquids are amines, ethers, especially lower alkyl ethers, organic acids, esters, ketones, glycols, alcohols and amides. Numerous specific examples of such moderately strongly hydrogen bonding liquids are given in the book entitled "Compatibility and Solubility" by Ibert Mellan (published in 1968 by Noyes Development Corporation) in Table 2.14 on pages 39 to 40 and these liquids all fall within the scope of the term polar organic liquid as used herein.

Examples of preferred polar liquids include alcohols such as C_1-10-aliphatic alcohols, especially methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol; glycols such as C₂.₆-alkylene glycols, especially ethylene glycol and propylene glycol; alcohol ethers such as 2-methoxy-, 2-ethoxy, 2-propoxy- and 2-butoxy-ethanol and -propanol, 3-methoxypropylpropanol, and oxypropylpropanol; alcohol esters such as methyl-, ethyl-, isopropyl-, butyl-acetates, ethylformate, methylpropionate, ethylbutyrate, 3-methoxypropylacetate, 3-ethoxypropylacetate and 2-ethoxyethylacetate; and dialkyl- and cyclo-alkyl ketones such as acetone, methylethylketone, diethylketone, di- isopropylketone, methylisobutylketone, di-isobutylketone, methylisoamyl ketone, methyl n- amylketone and cyclohexanone.

In water-based millbases, paints and inks the polar medium preferably comprises at least 25%, more preferably at least 50% and especially at least 75% by weight water relative to the total weight of the polar medium. In non-aqueous based millbases, paints and inks the polar medium is preferably methanol, ethanol, butanol, ethylacetate and butylacetate, including mixtures thereof.

The particulate solid is dispersed in the polar medium by any means known to the art such as grinding and milling in the presence of a dispersant. Preferably, the particle size of the solid is reduced to less than 15μ, more preferably less than 10μ, especially less than 5μ and more especially less than 3μ.

Preferred dispersants are derivable from polyalkyleneoxides and especially polyethyleneoxide.

The dispersant and SARS may be added separately at any appropriate stage in the preparation of the dispersion, millbase, paint or ink. However, it is generally convenient to add the SARS and dispersant together.

According to a further aspect of the invention there is provided a composition comprising a dispersant derivable from a polyalkyleneoxide and a SARS.

One preferred dispersant is a polycyclic aromatic compound having a water- solubilising poly(C₂.₄-alkyleneoxy) chain containing from 3 to 50 alkyleneoxy groups as disclosed in EP 555,950 particularly β-naphthol containing between 5 and 20 ethyleneoxy groups and especially β-naphthol containing 10 ethyleneoxy groups.

A second preferred dispersant is a dialkylaminoalkanol derivable from an ethylene oxide/propylene oxide copolymer as disclosed in GB 1 ,596,281 and especially that obtainable from diethylaminoethanol containing between 20 and 40 alkyleneoxide groups.

A third preferred dispersant is that obtainable by reacting a polyethylene glycol with a molar excess of hydroxycarboxylic acid containing from 4 to 17 carbon atoms or lactone thereof and/or with a C₃_₄-alkyleneoxide to form a polymeric diol and phosphating the diol to form a phosphate ester, including its salt thereof with an alkali metal, ammonia, amine, alkanolamine or quaternary ammonium compound. Dispersants of this type are disclosed in W095/34593. The dispersant derivable from a propyleneoxide/ethylene oxide/propyleneoxide block copolymer is especially preferred.

A fourth preferred dispersant is a phosphate ester of a compound of formula:

including salts thereof wherein

Y is a group RO- or a group H-(EO)_q-; R is C_1-10-alkyl; m and q are each, independently, from 5 to 50; and n is from 5 to 70.

PO represents propyleneoxy repeat units and EO represents ethyleneoxy repeat units.

Preferably, Y is a group H-(EO)_q. A fifth preferred dispersant is a phosphate ester of a polyalkylene ether block copolymer of formula:

R¹0(EO)_x(PO)_y-H wherein

R¹ is C,.₄-alkyl; and x and y are each, independently, 2 to 60.

Preferably the ratio of x to y is between 2:5 and 5:2.

EO represents ethyleneoxy repeat units and PO represents propyleneoxy repeat units.

A sixth preferred dispersant is a phosphate ester of a block copolymer of formula:

R²0(EO)_r(PES)_t-H wherein

R² is C- -alkyl;

PES is a polyester derivable from a cyclic lactone; r is from 5 to 60; t is from 2 to 30; and where the molecular weight of R²0(EO)_r is greater than the molecular weight of

(PES), EO represents an ethyleneoxy repeat unit.

Preferably, PES represents a polyester derivable from e-caprolactone and it is also preferred that the ratio of r to t is not less than 3:1.

The ratio of dispersant to SARS is preferably between 10:1 and 1 :1.

The dispersion comprising particulate solid, dispersant and polar medium preferably contains from 1 to 50%, more preferably from 2 to 20%, and especially from 2 to 10% by weight dispersant relative to the amount of particulate solid. The dispersion also preferably contains from 10 to 60%, more preferably from 30 to 50% and especially from 40 to 50% particulate solid based on weight of the dispersion.

The polar liquid medium may be a resin, especially a film-forming resin which is suitable for the preparation of inks and paints. Examples of suitable resins are polyamides, such as Versamid (Trade Mark) and Wolfamid (Trade Mark) and cellulose ethers such as ethylcellulose and ethylhydroxyethylcellulose. Examples of other paint resins are short oil alkyd/melamine-formaldehyde, polyester melamine-formaldehyde, long oil alkyd and multi-media resins such as acrylic and urea/aldehyde. Preferred resins are acrylic, styrene-acrylic, polyester, polyurethane, acrylic- polyurethane, vinylacetate and vinyl chloride polymers. Examples of preferred resins are those commercially available under the Neocryl and Neopac marks (Zeneca Resins) and the Joncryl mark (S.C. Johnson).

As disclosed hereinbefore the SARS may be used to increase the particulate solid loading in the dispersion or millbase. Millbases are generally prepared by grinding the pigment together with both a dispersant and resin in a polar liquid.

Typically, the millbase contains from 20 to 70% pigment based on the total weight of millbase. Preferably, the amount of pigment is not less than 30% and especially not less than 50% based on the total weight of millbase. The amount of resin in the millbase can vary over wide limits but is preferably not less than 10% and especially not less than 20% by weight of the continuous phase/liquid phase of the millbase. Preferably, the amount of resin is not greater than 50% and especially not greater than 40% by weight of the continuous phase/liquid phase of the millbase. The amount of dispersant in the dispersion or millbase is dependant on the amount of particulate solid but is preferably from 0.5 to 5% by weight of the dispersion or millbase. As disclosed hereinbefore, the SARS enables dispersions, millbases, paints and inks to be prepared which contain high particulate solid loadings and with a greater resistance to flocculation during preparation and use.

Thus, according to a further aspect of the invention there is provided a dispersion, paint or printing ink comprising a SARS, dispersant and particulate solid.

Whereas the SARS has been found especially beneficial when used as a fluidising agent in dispersions containing a dispersant derivable from a polyalkyleneoxide it has also been found that the SARS exhibits superior dispersing properties when compared with sodium-2-naphthylsulphonate and β-naphthol-10-ethoxylate. Thus, according to a further aspect of the invention there is provided the use of a

SARS as a dispersant for dispersing a particulate solid in a polar liquid medium.

There is also provided a dispersion comprising a particulate solid, SARS and a polar liquid medium.

As noted hereinbefore, the polar medium can be a resin and the resin itself may be used to help disperse a particulate solid in the polar liquid medium. In such circumstances, it is convenient to add the resin and SARS together to the particulate solid.

Hence, according to a still further aspect of the present invention there is provided a composition comprising a SARS and a resin. As noted hereinbefore, the SARS has also been found useful in preparing pale coloured paints or inks where a tinter pigment is dispersed in a polar liquid medium containing the SARS and then added to a mill-base containing a base pigment which is dispersed in either an aqueous medium or in a non-aqueous medium. The tinter pigment is preferably an organic pigment and the base pigment is preferably an inorganic pigment, more preferably a white pigment and especially titanium dioxide. It is particularly preferred that the polar liquid medium in which the tinter pigment is dispersed is a glycol such as ethyiene glycol or water, including mixtures thereof. The non-aqueous medium containing the base pigment is preferably a water-immiscible solvent such as an aliphatic or aromatic hydrocarbon, chlorinated hydrocarbon or petroleum distillate such as white spirits. The tinter pigment in the polar liquid medium is mixed with the mill-base under low shear agitation.

The invention is further illustrated but not limited by the following examples wherein all references to parts and percentages are by weight unless indicated to the contrary.

Examples 1-5 and Comparative Example A Fluidity of dispersions containing SARS

The SARS in the form of its sodium salt (0.05 parts) and an ethoxylated β- naphthol dispersant (0.20 parts) were dissolved in water (5.75 parts) in an 8 dram glass vial. 3mm Diameter glass beads (17 parts) were added followed by blue pigment (4.0 parts, Lutetia Cyanine ENJ ex. Zeneca). The dispersion was prepared by shaking on a horizontal shaker for 16 hours and the fluidity assessed. The results are given in Table 1 below:

TABLE 1

Footnote to Table 1

The numbers relating to SARS indicate the position of sulphonation

A is very fluid

B is fluid, gels within 10 minutes

Control is β-naphthol with 10 ethyleneoxy repeat units alone with 5.8 parts water in place of SARS.

Examples 6-10 and Comparative Example B

Examples 1 to 5 were repeated at a higher pigment loading by using 4.5 parts pigment and 5.25 parts water in place of the amounts given in Examples 1 to 5. The fluidity results are given in Table 2 below:

TABLE 2

Footnote to Table 2

The numerical values relating to SARS, Control, A and B are as described in the footnote to Table 1

C is fluid, gels within 1 minute

D is slightly fluid but gels immediately after shaking by hand

Examples 11 and 12

Examples 1 to 5 were repeated except replacing the blue pigment with the same weight of yellow pigment (Irgazine Yellow 3RLTN ex. Ciba-Geigy). The fluidity results are given in Table 3 below:

TABLE 3

Footnote to Table 3

Examples 12 and 13 Examples 1 to 5 were repeated except using 1.00 parts dispersant, 7.3 parts water and 1.20 parts black pigment (Black FW 200 ex. Cabot) in place of the amounts of dispersant, water and blue pigment used in Examples 1 to 5. The fluidity results are given in Table 4 below:

TABLE 4

Footnote to Table 4

The numerical values of SARS, Control A, B and C are as described in the footnotes to Tables 1 and 2. Examples 14 and 15

Examples 1 to 5 were repeated except using 0.1 parts SARS, 0.4 parts dispersant, 6.0 parts water and 3.50 parts green pigment (Monastral Green GN ex. Zeneca Limited) in place of the amounts and pigment used in Examples 1 to 5. The results are given in Table 5 below:

TABLE 5

Footnote to Table 5

The numerical values of SARS, Control and A are as described in the footnote to Table 1.

Examples 16, 17 and Comparative Example C

Examples 1 to 5 were repeated except using 0.2 parts dispersant or SARS, 5.30 parts water and 4.5 parts blue pigment instead of the amounts used in Examples 1 to 5. In these examples, the SARS alone is evaluated as dispersant. The fluidity results are given in Table 6 below and show that the SARS exhibits superior dispersing properties compared with sodium-2-naphthyl sulphonate and also β-naphthol-10-ethoxylate:

TABLE 6

Footnote to Table 6 The numerical values relating to the dispersant are the same as those relating to

SARS in Table 1. Control, B, C and D are as in the footnote to Tables 1 and 2.

E is thick, immovable gel. Examples 18, 19 and Comparative Example D

Examples 1 to 5 were repeated except using 0.12 parts SARS, 0.84 parts dispersant, 4.84 parts water and 4.20 parts blue pigment (Monastral Blue FNX ex. Zeneca Limited) in place of the amounts and Lutetia Cyanine ENJ used in Examples 1 to 5. The dispersion so obtained (0.1 part) was then mixed with an aqueous white base paint containing titanium dioxide (4 parts, Kem Aqua 280, ex. Sherwin Williams) under low shear agitation. The paint so obtained was coated onto card using a K-proofer and no 6 K-bar to give a film thickness of 60μ.

A drop of the final paint was then applied to the above paint-film and rubbed into the surface using finger pressure until the film became tacky. It was then dried at 20- 25°C for 4 hours.

The L, a and b colour co-ordinates were then measured for the rubbed area of film and also the dried film to which no additional paint had been applied. The difference between these two sets of measurements (ΔE) gives a measure of resistance to flocculation. The smaller ΔE, the greater is the resistance to flocculation.

ΔE = s/ (L_rL₂)² + (a, - a₂)² + (b, - b₂)²

where subscripts 1 relate to the dried paint film itself and subscripts 2 relate to the area of paint which has been finger-rubbed with a portion of the paint formulation. The results are given in the following Table 7:

Examples 20, 21 and Comparative Example E Examples 18 and 19 were repeated except using 0.12 parts SARS, 0.76 parts dispersant, 5.92 parts water and 3.20 parts red pigment (Monolite Rubine 3B ex. Zeneca Limited) in place of the amounts and blue pigment used in Examples 18 and 19. The results are given in Table 8 below:

Examples 22 and 23

Examples 18 and 19 were repeated except using the dispersion of Irgazin Yellow 3RLTN as described in Examples 11 and 12 in place of the Monastral Blue FNX dispersion. The results are given in Table 9 below:

TABLE 7

TABLE 8

TABLE 9

Footnote to Table 7 The numerical values relating to SARS are as explained in the footnote to Table 1. DMAMP 80 is an 80% (w/w) aqueous solution of 2-dimethylamino-2-methyl propan-1-ol which is used commercially to reduce flocculation.

Footnote to Table 8 The numerical values relating to SARS, A, B, C, D and Control are as explained in the footnotes to Tables 1 and 2. DMAMP 80 is explained in the footnote to Table 7. L, a and b are as explained in Examples 18 and 19.

Footnote to Table 9 The numerical values relating to SARS are as explained in the footnote to Table 1.

Examples 24 and 25

Examples 18 and 19 were repeated except using the dispersion of Black FW as described in Examples 12 and 13 in place of the Monastral Blue FNX dispersion. The results are given in Table 10 below

Examples 26 and 27

Examples 18 and 19 were repeated except using the dispersion of Monastral Green GN as described in Examples 14 and 15 in place of the Monastral Blue FNX dispersion. The results are given in Table 11 below:

Examples 28 to 30 and Comparative Examples F and G

Examples 18 and 19 were repeated except using 0.84 parts dispersant, 4.84 parts water and 4.2 parts blue pigment (Lutetia Cyanine BN ex. Zeneca) in place of the amounts and pigment used in Examples 18 and 19. The results are given in Table 12 below:

TABLE 10

TABLE 11

TABLE 12

Footnote to Tables 10 to 12 The numbers relating to SARS, A, B, C, L,, a_{1 t} b_{1 τ} L₂, a₂, b₂, ΔE and Control are as explained in the footnote to Tables 1 and 2 and Examples 18 and 19.

DMAMP 80 is as explained in the footnote to Table 7 and SCuPc is sulphonated CuPc in the form of its free-acid as disclosed in Example 1 of GB 1 ,596,281 and contains an average of 1.3 sulphonic acid groups for each CuPc molecule.

Examples 31 to 33

Examples 1 to 5 were repeated except using Lutetia Cyanine BN ex Zeneca in place of the Lutetia Cyanine ENJ and the SARS as indicated in Table 13 below. The fluidity was assessed after shaking on a horizontal shaker for 16 hours. The resistance to flocculation in a tinter formulation was determined as described in Examples 18 and 19. These results are also given in Table 13 which show that both the anthraquinone sulphonates exhibit advantage over the control but are somewhat inferior to anthracene-1 -sulphonic acid as fluidising agent.

TABLE 13

Footnote to Table 13

SARS, A, B, C, Li, a,, b.,, L₂, a₂, b₂, Δ E and Control are as described in the footnote to Tables 1 and 2 and Examples 18 and 19.

1-AQ is Anthraquinone-1 -sulphonic acid 2-AQ is Anthraquinone-2-sulphonic acid

Examples 34 to 38

An aqueous dispersion was prepared as described in Examples 1 to 5 containing copper phthalocyanine pigment (50 parts Microfine Blue 6088 ex SLMC), β-naphthol -10-ethoxylate dispersant (4.23 parts), fluidising agent (1.41 parts), water (35.86 parts), humectant (8.0 parts Humectant GRB2 ex Zeneca) and defoamer (0.5 part Bevaloid 6681 ex Rhone Poulenc). The viscosity of the resultant dispersion was measured using a Bohlin V88 Viscometer.

These blue dispersions were examined as tinters for a white base paint by adding to a white latex emulsion (Dulux Colour Dimensions - Mid base, ex ICI) in a ratio of 10 parts tinter to 90 parts base paint. The resistance to pigment flocculation was measured as described in Examples 18 and 19. The results are given in Table 14 below.

Table 14

Footnote to Table 14

1 -anthracene is anthracene-1 -sulphonic acid

1 -5-anthracene is anthracene-1 ,5-disulphonic acid

1-AQ is anthraquinone-1 -sulphonic acid (H is ex Hollidays; A is ex Akcros)

ΔE is as explained in Examples 18 and 19

Control is as explained in the footnote to Table 1

SCuPc is as explained in the footnote to Tables 10 to 12.

Claims

1. The use of a sulphonated polycyclic aromatic ring system containing 3 or more fused rings for improving the dispersion and/or flocculation resistance of a particulate solid in a polar liquid medium.

2. The use as claimed in claim 1 wherein the ring system contains fused phenyl rings.

3. The use as claimed in either claim 1 or claim 2 wherein the ring system contains either 3 or 4 fused rings.

4. The use as claimed in any one of claims 1 to 3 wherein the ring system contains one sulphonic acid group.

5. The use as claimed in any one of claims 1 to 4 wherein ring system is in the form of an alkali metal salt, ammonium salt or quaternary ammonium salt.

6. The use as claimed in any one of claims 1 to 5 wherein the ring system is either pyrene or anthracene.

7. The use as claimed in any one of claims 1 to 6 wherein the sulphonated ring system is either pyrene-1 -sulphonic acid or anthracene-1 -sulphonic acid.

8. The use as claimed in any one of claims 1 to 7 wherein the particulate solid is a pigment.

9. The use as claimed in any one of claims 1 to 8 wherein the polar liquid medium comprises a millbase, paint or ink.

10. A composition comprising a) a dispersant derivable from a polyalkyleneoxide and b) a sulphonated polycyclic aromatic ring system containing 3 or more fused rings.

11. A composition as claimed in claim 10 wherein the dispersant is a polycyclic aromatic compound having a water-solubilising poly(C₂.₄-alkyleneoxy) chain containing from 3 to 50 alkyleneoxy groups.

12. A composition as claimed in either claim 10 or claim 11 wherein the dispersant is ╬▓-naphthol containing between 5 and 20 ethyleneoxy groups.

13. A composition as claimed in any one of claims 10 to 12 wherein the dispersant is ╬▓-naphthol containing 10 ethyleneoxy groups.

14. A dispersion comprising a particulate solid, a dispersant derivable from a polyalkyleneoxide, a sulphonated polycyclic aromatic ring system containing 3 or more fused rings and a polar liquid medium.

15. A millbase comprising a pigment, a dispersant derivable from a polyalkylene oxide, a film-forming resin, a sulphonated polycyclic aromatic ring system containing 3 or more fused rings and a polar liquid medium.

16. A paint or printing ink comprising a pigment, a dispersant derivable from a polyalkyleneoxide and a sulphonated aromatic ring system containing 3 or more fused rings.

17. The use of a sulphonated polycyclic ring system containing 3 or more fused rings for dispersing a particulate solid in a polar liquid medium.

18. A composition comprising a particulate solid and a sulphonated polycyclic ring system containing 3 or more fused rings.

19. A composition comprising a resin and a sulphonated polycyclic ring system containing 3 or more fused rings.

20. A composition as claimed in claim 19 wherein the resin is selected from an acrylic, styrene-acrylic, polyester, polyurethane and acrylic-polyurethane resin.

21. A pale-coloured paint or ink comprising a) a tinter pigment dispersed in a polar liquid medium containing a dispersant and a sulphonated polycyclic ring system containing 3 or more fused rings and b) a millbase containing a base pigment dispersed in an aqueous or non-aqueous medium.

22. A paint or ink as claimed in claim 21 wherein the polar liquid medium is a glycol or water, or mixture thereof.

23. A paint or ink as claimed in either claim 21 or claim 22 wherein the base pigment is titanium dioxide.