WO2000064953A1

WO2000064953A1 - A process for production of micro-porous microspheres of polymers and polymeric pigments therefrom

Info

Publication number: WO2000064953A1
Application number: PCT/IN2000/000025
Authority: WO
Inventors: Vinod Chintamani Malshe; Anil Meghshyam Bendale
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-19
Filing date: 2000-03-21
Publication date: 2000-11-02
Anticipated expiration: 2001-09-19
Also published as: IN192012B; AU4609400A

Abstract

This invention relates to preparation of micro-porous microspheres of polymers, which are by themselves transparent colourless pigments and which can be converted to superior coloured pigments by simple dyeing process. Micro-porous microspheres of sub-micron size, of polymers are prepared by introducing micro-porosity generating agent(s) with the monomers(s) and/or additives for some functional groups and removing them after emulsion or suspension polymerization and/or cross linking reaction. Certain solvents are useful as micropores generating agents in the process. At the end of the reaction, the micro-porous microspheric polymer particles formed are coagulated and separated from the reaction mass, washed and dried to obtain micro-porous microspheres of sub-micron size. The product of the present invention has many uses: the transparent microporous microspheres are useful to carry many organic/inorganic molecules. Particular micro-porous microspheres having functional groups are useful as carriers for fixing specific colourants. Colorants: these micro-porous microspheres form good substrate for dyeing with normal dyes as described, and the coloured particles so prepared have extremely good dispensability and they are useful for food, pharmaceuticals, capsules, waterbased inks, cosmetics (cream, lotions), as pigments and colourants for plastics. The polymeric particles can also be used without dyeing as carriers for sustained release odourants, carriers of deodorants and medicines.

Description

A process for production of micro-porous microsphers of polymers and polymeric pigments there from.

The following specification particularly describes the nature of the invention and the manner in which it is to be perfonmed:-

This invention relates to a process for production of micro-porous microsphers of polymers. This invention particularly relates to a process of suspension or emulsion polymerization and cross-linking for production of micro-porous microsphers of polymers of sub-micron size. This invention more particularly relates to preparation of micro-porous microsphers of polymers, which are by themselves transparent colourless pigments and which can then be converted to superior coloured pigments by simple dyeing process.

Background and Prior art:

There are several properties in a substance, which make it a pigment. For example, it must be insoluble in any organic medium or water. The particle size must be extremely fine and it should be readily dispersible.

Organic pigments invariably are crystalline particles with a wide variety of shapes such as needles, platelets, different crystal forms and fractured crystal shapes because of which they tend to agglomerate. These particles have excess energy at all the sharp edges and the flat surfaces tend to stick to each other and a large number of particles tend to stay with each other making them difficult to disperse. The process of dispersion is energy intensive and special additives such as wetting agents, dispersing agents, are required to bring about the dispersion.

Again due to difference in free energy in different crystal forms, the crystals are unstable and tend to inter-convert from low to high stability state. This brings in loss of colour value, gloss, and change in hue over a period of time.

We observe, perfectly spherical particles of any substance do not have sharp edges or flat surfaces and therefore resist flocculation, in contrast to the crystalline particles. The best pigmentary materials would be perfect spheres of same dimensions, because, they would have least number of contact points , twelve to be exact

Though need to have such materials existed for a long period, so far there is no report on the synthesis of organic pigments with perfectly spherical shape. However, polymeric particles can be coloured and used as coloured particles. For example, US Patent 4636452 (1987) discloses preparation of coloured particles. US Patent 4617249 (1986) describes process for preparing dry toner composition by dispersion polymerization. A gist of most relevant patents in this field, in respect of present invention, is given below. Preparation of porous polymers such as well-known polyurethane foams has been described. In preparation of polyurethane foams, blowing agents such as chlorinated fluorocarbons are employed. US patent 5242954 (1993) describes a process for making cellular and microcellular polyurethane foams. In this process, the reactants provide a built-in capability to generate carbon dioxide as an in situ blowing agent. A poly isocynate is reacted with a carboxy-modified polyol to form polyurethane and carbon dioxide. Generally, such polymerization process is carried out in a mould to get the product of desired shape.

US Patent 4,552,812 (1985) describes a process for production of polyacrolein microsphers and grafted microsphers, which comprises subjecting an aqueous mixture of a polymerizable acrolein-type monomer to polymerization in the presence of an effective amount of a suitable ^•ionic surfactant which promotes microsphers formation upon polymerization of the monomer so as to form microsphers, the polymerization being effected at a pH between 8.0 and 13.7, and recovering the resulting microsphers and purifying the microsphers so recovered.

In general, different preparations of polyacrolein microsphers have been reported. It is suspension or emulsion polymerization either under basic conditions or with radical condition.

Under basic conditions, anionic or catioπic surfactants may be used for emulsification. It has been shown that changing the acrolein concentration, surfactant concentration or pH of the polymerization can control size of the microsphers. As the surfactant concentration goes up from 0 -3 % w/v the diameter of the microsphers falls down from 3 μ to 0.5 μ; as pH rises towards 12 the diameter of the microsphers drops down to <0.5 μ. They are hydrophobic in nature.

Addition of dimethylfoπmamide (or other related solvent e-g,dimethyl sulphαxide) to the aqueous medium increases the solubility of acrolein and results in the formation of uniform large polyacrolein beads.

Under radical polymerization polymer from 100 - 10,000 monomer-units is formed. Its structure is different from polymerization under basic conditions. Its hydrophilicfty increases with increase in pH of the polymerization.

This patent also describes preparation of hybrid microsphers wherein anionic polyacrolein microsphers have been coated with the radical microsphers.

US Patent 4,880,432 (1989) discloses a process for preparing particles coloured with a dye which comprises (a) forming, by a free radical dispersion polymerization process in a non- aqueous solution, polymeric particles having attached thereto stabilizing copolymers with at least one functional group capable of undergoing a chemical reaction with a dye, the particles having an average diameter of from about 0.1 to about 20 microns; (b) adding a dye to the polymeric particles having attached thereto stabilizing copolymers; and (c) effecting a chemical reaction between the dye and the stabilizing copolymers that results in the dye becoming covalently bound to the polymeric particles. Also disclosed is a liquid electrographic developer composition comprising a liquid medium, a charge control agent, coloured polymeric toner particles prepared as stated above and having an average diameter of from about 0.5 to about 5 microns.

In one embodiment of the invention colourless stabilized polymeric particles are first formed and subsequently coloured by forming co-valent bonds between the polymers and dye molecules. The polymeric particles comprise a macroscopic thermoplastic resin core to which is chemically or physically attached an amphiphatic block or graft copolymer steric stabilizer.

Preparation of colourless particles has been done by dispersion polymerization in solvents like iso-octane, toluene. For washing, solvents like cyclohexane have been used.

Preferred core materials are polyvinyl acetate, poly vinyl pyrrolidone, polyvinyl acetate, methyl methacrylate, styrene, and ethyl acrylate and copolymers of any of these monomers.

US Patent 3957741(1976) describes preparation of a composition essentially of uniformly shaped hydrophilic, swellable, porous, round beads, of uniform diam. < 2 μ prepared by the aqueous suspension polymerization of an acrylic monomer containing an hydroxy or amino group such as hydroxyethylmethacrylate (HEMA), 1-35 % of compatible commoner such as lower alkyl methacrylate, acrylic or methacrylic acid, styrene and vinyl toluene may be present in the polymerizable mixture; a cross linking agent such as liquid [polyvinyl] diene or triene compound. Cross-linking is brought about under nitrogen inert atmosphere, by heat about 50 -100°C for about 24 hrs without catalyst or by γ-ray irradiation at ambient temperature for about 15 mts. An aqueous soluble polymer -polyethylene oxide [mol. wt. ~4, 000,000] is added to the polymerizable mixture, and removed by washing the reaction product with boiling water. The dry material is ground into individual beads.

These beads are intended for use as adsorbents in chromatography and as markers for studies of cell surface receptors, in gel filtration and permeation, separation and analysis -

US Patent 4,046,720(1977) a divisional of the above patent claims similar composition based on cross-linked polymer of acrylamide. Presence of 1-35 % co-monomer selected from a lower alkyl methacrylate, acrylic acid, methacrylic acid, styrene or vinyl toluene has also been claimed.

Employment of polyethylene oxide polymer has been extended to polyethers mol.wt 300,000 - 10,000,000; this extension includes polyethers of alkylene oxides such as ethyiene oxide, propylene oxide or their mixtures.

The agglomerates of the beads are dispersed in non-solvent liquid and crushed or ground to get the uniformly shaped, hydrophilic, swellable, porous round beads, at least 80% of which are having diameter less than 2 microns. They also claim at least 90% of beads having diameter between 0.001 and 2 microns. Use of cross-li king agent N,N'-methylene-bis- acrylamide has a separate claim. It will be seen that these porous round beads, of the above two US patents 3957741(1976) and 4,046,720(1977) are mainly prepared from acrylic type of monomers. On the other hand, microsphers preparations as described in US Patents 4,552,812 (1985 ) and 4,880,432

(1989) are not porous and they have involved additional process for treating dyes, for coating core microsphers; to place a dye on those microsphers. This puts two limitations on. the product. Namely, the size of the particles would not be uniform due to suspension polymerization process, the particles would be coarse and the amount of dye thai can be deposited on the particle is strictly limited to the surface where the readable polymer is present which can not be present in a large concentration.

The nearest prior art process is preparation of microgels by combination of monomers of different refractive indices for use as titanium dioxide substitute pigment. J W Hook and.R E Harren (in Organic Coatings Science and Technology", Vol. 7, Marcel Dekker Inc., N.Y. & Basal, 1984 p. 299) report Polymer OP-42, OP-62 & OP 62-10 of Rohm & Haas, USA , as Opaque Polymer in a hard non-film forming emulsion polymer which contains a fully encapsulated water filled core. When an opaque polymer bead dries in a paint film, the water irreversibly diffuses out of the core, having a fully encapsulated air void. Once the film is fully air-dried the water does not reenter the void. During the drying process, the ha d polymer shell surrounding the core does not coalesce but retains its shape thus maintaining the air void integrity.

In "Hand Book of Coating Additives" Vol. 2, Ed. Leonard J Calbo ( Marcel Dekker, 1987, p 225.) are described similar pigments also called "Vesiculaled beads" which were first introduced as "Spindrift" in Australia in particle size 5 - 20 μm in diameter. The use of these materials is limited to flat paints due to their large size and solubility in solvents. Following patents show different methods of preparation of coloured polymeric particles : US Pat. 3819557(1974) describes method for preparation of improved polymeric pigments for use in paper coatings by an emulsion polymerization process comprising the steps of (1) emulsion polymerizing at least 50 weight percent of total monomer in absence of emulsifier, (2) adding an emulsifier and (3) continuing emulsion polymerization of the remaining monomer charge.

US Pat. 4880432 (1989) describes process for preparing coloured particles in which, polymeric particles are prepared and subsequently reacting them with a dye to form a polymeric particle having a dye covalent bonded thereto. A dye molecule reacting with reactive groups attached to the soluble stabilizing polymers brings about coloration of polymeric particle.

The prior art reported in this patent is in short as follows: i. Preparation of polymeric particles of diameter up to 4 microns by suspension polymerization in aliphatic medium has been reported. Process for coloration of polymeric particles using polymerizable dyes as co-monomers during free radical dispersion polymerization process in which polymer particle is formed has been reported ii. Process for preparing non-aqueous dispersions of poly(vinyl acetate) particles stabilized with poly(2-ethylhexyl methacrylate)and labeled with fluorescent dyes in the core and stabilizer polymer phases. iii. US Pat 4476210, discloses process for dispersing or dissolving the dye in the polymeric particles comprising a thermoplastic resin core with an amphipathic block or graft copolymer steric stabilizer irreversibly chemically or physically anchored lo the resin core, iv. US Pat 4636452, colours polymeric particles prepared from selected polymers and monomers by a specific method, by dispersing or dissolving dye molecules therein, v. US Pat 4617249, process entails preparing a solvent medium containing disperse steric stabilizers, monomers and initiator compounds, adding a cross linking compound, heating the mixture to polymerize the monomers, and separating the formed particles from the mixture. Diffusing a dye, present in a solvent solution, into the polymer mixture may effect coloration of the particles. vi. British Pat 1181287 method is coupling diazotized colouring material with monomer during free radical polymerization. The coloured material is then processed by wet grinding ball milling etc. vii. Japanese Pat. Appln. No. 54029/78, the colorant (pigment or dye) may be attached to polymeric particles colloidally, suspended in a liquid chemically, or by secondary forces or by surface adhesive forces. In another embodiment, bonding brings about chemical bonding with the precursor or grafted side chain of the polymer prior to formation.

US Patent 4093793, claims a structurally dyed water-insoluble macromolecular material containing, in copolymerized form, acrylamide, at least one colourless monomer selected from the group consisting of vinyl chloride, vinyl acetate, styrene, acrylic acid, acrylates, and acrylonitrile and at least one anthraquinone dye having a group containing a polymerizable double bond, obtained by reacting for one or two minutes, in an aqueous medium and in the presence of a tetravalent cerium complex, the dye with the acrylamide and then introducing in the medium said colourless monomer and continuing the polymerization, the amount of dye being from 0.1 to 25% by weight of the colourless monomer and the amount of acrylamide being from 0.5 to 50 % by weight of the colourless monomer.

The coloured polymer particles described in above patents are in general for use in (liquid) toners, photographic developers and the like jobs; and none of these use microporous microsphers of crosslinked polymeric particles for making colour pigments. Object

The main object of the present invention therefore relates to .a process for preparation of micro-porous microsphers of sub-micron size of polymers by polymerization of any type of monomer including crosslinkers, with or without functional groups to hold the regular dye molecules inside the pores. We conceived that porosity could be generated in the polymer by presence of non- polymerizable low boiling liquid during polymerization process, and venting them out of the system once the cross-linking imparts a rigid structure to the polymer. Such a porous polymer will have same venting channels to fill the pores by dye, or any other required molecule.

Our approach is to add non-polymerizable micro porosity generating agents to the polymerizing mixture, and carry out polymerization of the monomers in suspension or emulsion form and remove the porosity-generating agent after the polymerization, without allowing them to be entrapped in the polymer.

Pigments such as titanium dioxide, lithopone , zinc oxide or litharge, red lead, iron oxide, chrome yellow, Prussian blue are inorganic; while phthalocyanine blue, carbon black could be considered as organic. They are used mainly for their opaque and protective characteristics. The colour strength of organic, inorganic pigments is limited mainly because of the tendency of complex organic pigment molecules to flocculate.

Macromolecular dyes are intrinsically and structurally coloured polymers in which colour groups are incorporated during formation of certain polymers. However, during their preparation structural configuration of the Chromophoric group changes, discoloration occurs due to free radical reactions of polymerization and they are not satisfactory as pigments. Such macromolecular materials have been employed by what is known as combinatorial approach for synthesis of drugs, proteins, catalysts, peptides and in some cases of drug delivery system wherein the relevant molecules are supported on the appropriate tailor made macromolecule. Janda Kim D.and Hyunsoo Han ; J Amer. Chem. Soc; 1996, 118, 2539. Janda Kim D. and Dennis J Grevert; Chem. Rev.;1997, 97, 489.

Tinting colours are also at times added to the pigments to get the desired shade / tint effect on the final product to which the pigment is applied. But such products are not stable and discoloration occurs in a short time. There is a need to produce newer pigments with different colours that will be stable in use over a longer period. It would be most preferable to have non-flocculating pigment particles that could be coloured to the desired shade. In our application, we describe processes to obtain such microporous polymers, which could fulfil the need of colorable pigment particles and also process by which to obtain these coloured particles.

Summary of Invention:

Accordingly, the present invention relates to a process for manufacture of micro-porous microsphers of sub-micron size of polymers comprising, i. mixing micro-porosity generating agent(s) with the monomers) and/ or additives for some functional groups: ii. emulsifying the mix obtained at the end of step I. in water with the help of emulsifying agent(s) to give homogenous emulsion, or making micro suspension of the said mix in water or non-aqueous phase with the help of suspending agent(s): iii. subjecting the said emulsion or the said suspension obtained at the end of step ii, to polymerizing and/or cross-linking reaction with addition of initiator to form the micro- porous microsphers of the polymer; iv. removing the non-polymerizable micro-porosity generating agent from the reaction mass at the end of step (iii) when the reaction is complete; v. Coagulating the micro-porous microspheric polymer particles in the reaction mass remaining after step (iv) by addition of polymer-coagulating agent(s) to the said reaction mass; separating the coagulated micro-porous microspheric polymer particles from the reaction mass, washing and drying for recovering the polymers formed in the form of micro-porous. vi. microsphers of submicron size or directly subjecting the emulsion to dyeing process.. vi. Preparation of dyeing solution comprising colouring compounds or soluble Leuco compounds which develop colours on oxidation, or soluble reactive dyes or soluble component of colouring compounds which form an insoluble colour on subsequent contact with its colour forming coupling component in solution, in solvents such as water, alcohol at required pH; vii. Soaking the said MPMS polymer particles in the solution for 30 - 60 minutes, at 20 -

150°C under pressure; viii. Separating the soaked particles obtained at the end of step (iii), washing, drying; to obtain the coloured polymeric pigment particles, when contact with coupling component of the colouring compound is not required to develop the colour; ix. Preparing coupling solution comprising said coupling component, when coupling component of the colouring compound is required to develop the colour, x. Soaking the dry particles obtained at the end of step (iii), only when second component of the colouring compound is required to develop the colour, in said -coupling solution of the second component prepared in step (v) for 30 - 60 minutes at 0 - 150 °C under pressure when required; xi. Separating^' the soaked particles obtained at the end of step (vi), drying, washing, and drying; to obtain the coloured polymeric pigment particles.

In this process, colouring compounds are selected from group consisting of water / alcohol soluble dyes such as direct dyes, acidic dyes, basic dyes, fluorescent dyes; from group consisting of reactive dyes such as vinyl solfones, isocyanurates, sulfonyl and carbonyl azides dyes, particularly when MPMS polymer particles have functional group that supports reaction or from group consisting of water / alcohol soluble Leuco compounds of vat dyes, of alizarin, quinizarin or anilines that develop colour on oxidation on contact with air; from group consisting of water / alcohol soluble components of dyes such as Naphthol or diazo dyes, mordents of mordant dyes, inorganic pigment components such as lead salts such as forming lead chromate, iron salts such as ferric salts forming iron oxide, phthalogens forming phlhalocyanine, that develop colour on subsequent contact with the corresponding coupling / colour forming component. The colour development could also be affected by using some part of the polymer support to partake in the reaction. These could be cyano groups or other aromatic phenolic groups which could be a part of the polymer or could be built over the functional groups of the polymers. In the case of the reactive dyes, the colour content of the particles depended on the functional groups present on the polymer support and the strength of the reactive dye. For example, in a polymeric particle which had 9.1% by wt. of the monomers hydroxy functional monomers, the reactive dye content was 27.5 % by wL the dyed polymer. It could be increased to 30 % by wt. using high molecular wt. reactive dyes.

Brilliant red, violet, green and yellow colours / pigments could be produced with right dyes such as alizarin, Novinone jade green and Quinizarin, heating the dyeing solution containing said micro-porous polymer particles up to 150 °C under pressure, if necessary, maintaining at that temperature till the dye bath is exhausted, then separating the coloured particles from the dye bath, followed by washing, oxidizing etc., Generally, the dye bath is exhausted with higher pressure/ temperature, but the usual method of exhausting dye bath with addition of salt may be followed at the end of step (ii). A good wash with water, before drying prevents any salt deposition.

Drying of the coloured pigment particles is preferably by vacuum drying at ambient temperature.

If the dye chosen is basic, the MPMS polymer particles are selected from acidic functional polymers.

If the dye chosen is reactive dye such as having β-sulphato ethyl sulDhones, then the polymer chosen for making MPMS polymer particles is hydroxyl functional type.

Monomers are selected from group consisting of styrene, methyl methacrylate (MMA), acrylonrtrile (ACN).

Emulsifiers are selected from group consisting of a) Non-ionic emulsifiers such as nonyl phenol ethylene oxide (Nyp.EO) condensates, ethylene oxide (EO), propylene oxide (PO) co- or block co- polymers, castor oil derivatives, such as castor oil: ethylene oxide condensates, vegetable oil derivatives, silicones, fluorocarbons condensed with EO or EO.PO and / or Gemini surfactants; OR b) Anionic such as sodium lauryl sulphate (SLS)."dodecyl benzene sulphonate (DDBS), soap of different fatty acids or combinations thereof, naphthalinic sulphonate 0.1 - 10 % by wt on monomer and combinations thereof. Additives for functional groups: Addition of a functional monomer 0.5 ~ 20 % by wt of total composition is optional. Any monomer having such functionality as carboxylic, amine, quaternary, amide, allyl chloride, hydroxyl, secondary hydroxyl, primary hydroxyl, sulfonic acid, methane sulfonic acid, are useful. Functional monomers are preferably chosen from monomers such as acrylic acid, methacrylic acid, Hydroxy methyl acrylate or hydroxy ethyl acrylate HEMA, Gtycedyl Methacrylate, Acrylamide, 2-acrylamido, 2 methyl propane sulfonic acid (AMPS), Styrene sulfonic acid (SSA), Sulfonyl phenyl methallyl ether (SPME), Strong base Amine type monomers such as trimethyt amino ethanol methacrylate, or their precursors such as vinyl benzyl chloride (VBC), 2 hydroxy 3 chloro propyl methacrylate (CHPMA), 0 -20 % by wt of monomer.0.1 - 10 % by wt. of total composition are usually employed for this job.

Cross-linking agent is essential and preferable amount is 15 - 20 % of the monomer mix. Cross linking agents-such as divinyl benzene (DVB), Ethylene glycol di methacrylate (EDMA), or any other cross linking agent such as poly functional derivatives of poly hydroxy alcohols and unsaturated acids for example glycerol trimethacrylate, penta erythritol tetra methacrylate or the like may be used from 0.1 - 100 % by wt. of total monomer.

Micro-porosity generating agents:

There are 4 types of Micro-porosity generating agents: a) Blowing agents such as low boiling liquids such as pentane, or fluorocarbons, azo bis isobutyronitrile, azodicarbonamide, sodium bicarbonate which blow off in to gaseous products on heating to 120 - 180 °C with or without added catalysts called kickers b) Solid paniculate material that dissolves in acid or alkali, such as calcium carbonate c) Non-crosslinkable polymer such as polystyrene .that dissolves in monomer mix and d) Solvents which are miscible with monomers but do not dissolve resulting polymers. e) The scope of the invention covers use of any of these Micro-porosity generating agents alone or in combination in the process of present invention. The preferred Micro-porosity generating agent from ease of operation is a solvent with a boiling point below that of water and with very low water miscibility in which the polymer is insoluble

The preferred micro-porosity generating agents are selected from group of compounds such as aliphatic or aromatic solvents; primary, secondary or tertiary alcohols that stay unpolymerized in polymerization process and leave the microporous microsphers system on vaporization or on extraction with solvent and are preferably partially water soluble and having low boiling point or forming an azeotrope with water.Micro-porosity generating agents are selected from group of solvents such as tetrahydronaphthalenes, iso butanol, iso amyl alcohol 2-ethyl ..exanol, cyclohexanol, C ₁₂.₂₂ primary alcohols or a mixture thereof Solvents such as iso-butyl alcohol are chosen to control porosity of the product. The solvent chosen has to have low water solubility and low boiling point, preferably less than that of water; or forming an azeotrope with water.

.Optional addition of higher alcohol C₂₂ helps to increase pore size; it is removed by solvent extraction after polymer particles have been recovered.

Water form the aqueous phase in emulsification; the amount used is 50 -300 % of (monomer and porosity generating agent) mixture.

Suspension medium: Apart from the most preferred non solvent, water, Aliphatic, aromatic, alicyclic hydrocarbon solvents such as octane, toluene cyclohexane are used as suspension medium for polymerizing of monomer in Suspension State.

Suspension agents: Protective colloids are used as suspending agents in suspension polymerization. They are chosen from group of cnllnklal solution forming/ and protecting, substances such as polyvinyl alcohol, carboxymethyl cellulose, hydroxy ethyl cellulose, starch, lignin, and gelatin when watei is used as suspending medium. Chlorinated rubber can be used for organic medium. The preferred concentration of this agent is in the range of 0.1 to

25 % on the weight of the suspension medium the most preferred concentration being 0.5%

Initiators: Common radical polymerization initiators such as peroxides, hydroperoxides and persulfates can be employed for this purpose

Irradiation: Alternately this polymerization can be brought about by irradiation also. This includes ultraviolet, β- and γ-radiation produced by radioactive substances.

Polymerization temperature is 30 - 100 °C; in a closed container, allowing pressure to build up if necessary. Time for completion of reaction is about 7-8 hrs.

Coagulating agents; These are electrolytes, polyelectrolytes such as sodium chloride, sulphate, alum or cationic or anionic polyelectrolytes.

Description of the product:

Particle size: 0.05 - 5 μ or more as per need; mono spheres or poly-disperse.

Can be controlled from 0.5 - 6 μ by choosing right process conditions.

Porosity: 0 - 70 % by vol. Of the particles

Can be controlled 0 - 70 % by volume of particle by choosing the concentration of porogenic agent.

Pore size distribution: 5 - 1000 A⁰ narrow or wide as per the need. Water insoluble matter: not more than 0.1 % by wt of final polymer

Toxicity of. the polymer particles: Non-toxic in most cases. The monomers of acrylic type are- in use over number of years as parts of dental products and pharmaceutical preparations

Uses:

The product of the present invention has many uses: the transparent microporous microsphers are useful to carry many organic / inorganic molecules. Particular microporous microsphers having functional groups are useful as carriers for fixing specific colourants; Colourants: These micro-porous microsphers form good substrate for dyeing with normal dyes as described here and the coloured particles so prepared are useful for food, pharmaceuticals, capsules, water based inks, cosmetics (creams, lotions), abrasives for tooth pastes, slow release low contact sunscreens. As pigments and colourants for plastics, sustained release odouronts, carriers of deodorants and medicines.

Examples:

The objects of the invention, its advantages and means for attaining the same are disclosed hereunder in greater detail with reference to non-limiting embodiments of the same by way of Examples. The Examples are by way of illustration only and in no way restrict the scope of the invention

Example I: Preparation of MPMS-A

A monomer mixture was made as follows:

10 parts acrylic acid (functional monomer) was mixed with 90 parts 1:1:1 mixture of styrene: methyl methacrylate (MMA): acrylonitrile (ACN). To this was added) divlnyl benzene (DVB) (as 50 % DVB) 16% by wt. on monomer mixture; and iso-butanol (solvent as micro-porosity generator) in equal volume as monomer mixture.

This monomer composition along with cross linking agent and solvent (monomer mixture) 232 parts was charged through reservoir for monomer in the usual stirred cylindrical glass reaction vessel with assembly providing thermometer, condenser, and Teflon blade stirrer in which was taken aqueous phase - water 250 parts containing 5 parts of an emulsifier sorbitol mono-oleate, and 2.5 parts of sodium lauryl sulfate (as emulsifying agents) over a period of 6 hours.

The emulsion (oil in water) was formed on stirring at room temperature. Ammoniupri persulphate 0.2% by wt. on total wt. of monomer mixture added as polymerization initiator to the emulsion either in a single lot or over a period of time as a solid or as a solution.

The polymerization reaction was allowed to go to completion by heating the contents to and maintaining the mixing / stirring / homogenizing at 70 °C for 6 hours.

Additional water 200 ml was added to the reaction mix.

The solvent was distilled off by raisiny the temperature of the contents above 90 °C.

The contents were then cooled to 30 °C; and sodium chloride (30g) was added and maintained until the polymeric particles were coagulated and separated from the aqueous phase completely.

The mixture was then filtered, washed with demineralized water till the washings were free of NaCI and dried under vacuum of 300 mm Hg at 60-70 °C. The particles were screened through 350 mesh to remove any grit material. The product - microporous microsphers of the polymer particles, obtained (named MPMS-A) was 105 parts representing 90.5% yield of theoretical yield. Water insoluble matter was found to be not more than 0.1 % by wt of final polymer.

The characteristics of the product are given in Table 1.

Example II : Preparation of MPMS-B

A mixture of 50 g of monomers containing styrene 53.7 %, hydroxy ethyl methacrylate (HEMA) 9.1 %; ACN 30 % and ethylene glycol dimethacrylate (EGDMA) 7.2 % was mixed with 50 g of toluene This mixture was emulsion polymerized using the procedure as described In Example I. After the polymerization the temperature of the reactants was raised to 90 °C and the solvent was distilled off as an azeotrope with water. The contents of the reactor were cooled to room temperature and an electrolyte such as sodium chloride or aluminum sulfate was added, polymer was separated as described in Example 1. The product was a cake of the porous, spherical, carboxyl functional colourless crosslinked polymeric particles, which were then washed and dried under vacuum. Yield of polymer was 90 %by wt.

The product the microporous microspherical polymer particles obtained (named MPMS-B) showed 5.1 % grits, and the particles had 34.6 % pore volume and acid value 47.2.

Due to the perfectly spherical shape they do not flocculate and therefore are readily dispersive in different media, characteristics never found in conventional pigment particles.

Characteristics of the product obtained are given in Table 1.

Example III : Preparation of MPMS-C

The microporous microspherical polymeric particles, were prepared from monomer mix of particles of Styrene (commercial, purity 99.7 %by wt.) 54.6 % by wt., acrylonitrile (commercial, purity 99 %by wt.) 31.7% by wL, EGDMA (commercial grade containing 68 % by wt of

EGDMA and 12 % by Wt. HEMA) 7.20 % by wt. and Acrylic acid (commercial 99 % by wt.)

6.5 % by wL as per Example I

The microporous microspherical polymer particles obtained ( MPMS-C) had the following specifications:

Particle size 1 μ ; Porosity : 50% by vol.; most of the pores had near 100 A⁰ diameter

Characteristics of the product obtained are given in Table 1.

Example IV: Preparation of MPMS-D

In this Example the microporous microspherical polymeric particles, were prepared by the process of Example I above except that the CDmposition of monomers used was, styrene 31.5 % by wt., methyl methacrylate 26.0 % by wt., EGDMA 10.0 % by wt., and HEMA 32.5 % by wt. The microporous microspherical polymeric particles, prepared were screened, grit 3.4 % by wt. separated out. The product obtained (named MPMS-D) had hydroxyl value = 76.2 (calculated 129.3); porosity = 0 % by vol. and specific gravity = 1.199. Characteristics of the product obtained are given in Table 1.

Table 1: Characteristics of the products obtained

Example 1 Example 2 Example 3 Example 4 MPMS-A MPMS-B MPMS-C MPMS-D

Particle size 1 - 2 μ 2 - 5 μ 1-2μ

1-2 μ

Porosity % 35.5 35.9 37 0.0

The particle size was determined by sedimentation and the porosity, by weight increase on saturating dry powder with water followed by filtration under vacuum. Microscopic examination of particles by electron microscopy revealed them to be perfectly spherical uniform particles .

Particle size : 0.5 - 5 μ or more as per need ; mono spheres or poly disperse particles can be controlled from 0.5 - 6 μ by choosing right agitator in the polymerisation reaction

Porosity: 0 - 70 % by vol. of the particles. Porosity can be controlled 0 - 70 % of the volume of particles by choosing right % concentration of the porogenic agent or the blowing agent.

Pore size distribution : 5 - 1000 A⁰ narrow or wide as per the need can be obtained by varying the swellability of the polymer in the solvent

Example V : Preparation 61 Bright Pink Pigment based on MPMS-A :

5 g of Rhodamin B was dissolved in 100-ml water to prepare the dyeing solution.

20g microporous microspherical polymeric particles obtained in Example I (MPMS-A) were added to the dyeing solution. The mixture was heated to 80 °C and the particles were allowed to soak for one hour.

The particles were separated by filtration, washed with demineralized water and dried in vacuum below 90 °C.

The bright pink coloured Pigment based on MPMS-A was obtained.

Use of the pigment:

These bright pink coloured pigment based on MPMS -A particles were mixed* with low- density polyethylene injection moulding powder, at different proportions from 0.1 - 1.0 % by wt., on a single screw type injection moulding machine and the resulting objects emerged with uniform colour in all the mixtures. The hue saturating at 0.8 % pigment on the polymer.

This example shows that there is no need to premix the moulding powder with this pigment, which is commonly required for organic or inorganic pigments.

Example VI: Preparation of Red Pigment based on MPMS -B:

A dyeing solution of a reactive dye Remazol Red D was prepared in water at a concentration of 100 gpl.

The dried microporous microspherical polymer particles of Example II (MPMS -B) . were soaked in the above dyeing solution at room temperatures and the temperature was raised to 60 °C for 2 hrs. The dye was fixed by its reaction with the functional group. The product was washed, and dried as in Example V above.

The colour content of the particles depended on the functional groups present on the polymer support and the strength of the reactive dye. Since 9.1% by wt. of the monomers were hydroxy functional monomers, the reactive dye content was {27.5] % by w the dyed polymer.

In the process of drying and washing the Leuco vat dye was air oxidized and developed its full colour.

Example VII: Preparation of Red Pigment based on MPMS -A:

In this Example a pigment molecule was synthesized inside the hollow space micro pores of the microspherical polymeric particle. A solution of β-Naphthol was prepared in an equimolar amount of alkali and it was filled inside the pores of the microporous microspherical polymeric particles obtained as per Example I (MPMS -A) by soaking the solution at room temperature and particles were dried without washing . A solution of a diazotized p-nitroaniline was prepared at 5 °C. The dry β-Naphthol deposited MPMS-A particles were soaked in the diazo solution of equivalent to the β-Naphthol . This resulted in coupling of the two components inside the pores of the microporous microsphers to give polymeric pigment particles. The resulting pigment particles had bright red colour and a very fine texture.

These coloured particles of Red Pigment based on MPMS-A were then washed repeatedly until free of electrolyte, dried in vacuum at 50^JC and stored.

Example Viii: Preparation of Bright Pink Pigment based on MPMS-C:

The Rhodamin B dye (Colour Index No. C I 560) 5 g was dissolved in 100 ml water to make the dyeing solution.

20g micro-porous microspherical polymeric particles (MPMS-C) prepared as per Example III were added to the dyeing solution.

The mixture was heated to 80 °C and the panicles soaked in it for one hour. The dyed particles were separated by filtration, washed with water, and dried in vacuum below 90 °C. The dry particles were screened through a 350 mesh sieve, removing a small portion of grit material.

A bright Pink Pigment based on MPMS-C waϊ. obtained.

Use of the pigment particles:

These pigment particles were mixed with low-density polyethylene injection moulding powder, at different proportions from 0.1 - 1.0 % by wt. on a single screw type injection moulding machine and the resulting objects emerged with uniform colour in all the mixtures. The hue saturating at 0.8 % pigment on the polymer.

Example IX: Preparation of Red Pigment based on MPMS -D

10 g of Reactive dye Ramazole Red B was dissolved in 300 ml water containing sodium sulfate (Na₂S0₄1/2 H₂0) 20g, sodium carbonate ( Na C0₃) 2.48g.

The dry non-porous microspherical polymeric particles (MPMS -D) [100 g] prepared as in

Example IV were added to the dyeing solution.

The mixtμre was heated to 80 °C for one hour, with addition of soda ash as required to maintain pH alkaline.

The dyed particles were then filtered and washed with water, and dried in vacuum, at 70 °C.

The bright red coloured Pigment based on MPMS-D was obtained.

These pigment particles were mixed with low-density polyethylene injection moulding powder, on a single screw type injection moulding machine as in Example IX. Resulting polyethylene was uniformly coloured as in EΞxample IX.

Example X : Preparation of Green Pigment based on MPMS-B

Novinone Jade Green 10g. was dispersed in water 37 ml. To this dispersion was added

NaOH flakes (2g). and sodium hydrosulphite (Na₂S₂0₄) 2g. The dispersion was heated to 90

°C till all the dye dissolved.

To this dyeing solution were added 50 g of microporous polymeric particles prepared as in

Example II, MPMS-B with 1cc /g of pore volume. The particles were allowed to soak in the solution for an hour. The dyed particles were filtered, dried in the air for 30 minutes at 60 °C and finally in vacuum at 80 °C /300mm Hg.

On drying these were washed repeatedly 5 times with de-mineralized water till they became free of electrolyte. In the process of drying and washing the Leuco vat dye was air oxidized and developed its full green colour.

The green coloured particles were found useful for colouring polyethylene as in {Example I.

Example XI: Preparation of Red Pigment based on MPMS-C:

In this Example a pigment molecule was synthesized inside the hollow space of the microporous microspherical polymer particles MPMS-C, prepared as described in Example III and having 50% porosity. β-naphthol solution 20 % by wt., was prepared in an alkali . The quantity taken was equal to pore volume of MPMS-C polymer particles to be soaked in it. After soaking the porous polymeric pigment particles with the above solution , the particles were dried. 10

Two solutions of the diazotized (a) m-nitro,p-toluidene and (b) p-toluidine, [equal to 80 % of the pore volume of the microporous microspherical polymer particles] were prepared at 5 C. The β-Naphthol deposited MPMS-C polymeric particles were added to each of these solutions. This resulted in formation of coloured micro-spherical polymeric particles on coupling of the two components inside the micropores of the MPMS-C polymeric particles. The resulting pigment particles were bright red when m,nitro p-loluidine was used, and yellow when benzidine and phenyl methyl pyrrozolone were used as coupling compound and diazo compound respectively. All the particles had a very fine texture. These were then washed repeatedly until free of electrolyte, dried in vacuum and stored.

Example XJJ: Preparation of Blue Copper phthalocyanine Pigment based on MPMS-A: Materials used in this example were : Phthalogeπ, Copper chloride and Urea. A solution of phthalogen (6 %) by wL in alcohol was prepared. Urea (3.5 %)was added to it with 1% cuprous chloride. Micro-porous microspherical polymeric particles MPMS-A (100g), prepared as per process of Example I, were added to- the dyeing solution till it was saturated. The particles were filtered and dried at 80 °C and repeatedly soaked in the same solution till about 20% phthalocyanine was Jeposited in the pores of the particles and dried at 130 °C _tor 10 min.

The blue coloured particles were then repeatedly washed , filtered dried in vacuum to obtain Blue Copper phthalocyanine Pigment based on MPMS-A Advantages of the invention:

The process of present invention is simple and provides beautiful microporous microspherical ( MPMS) polymeric particles, which are opaque or transparent. Such particles find a variety of applications, the central point of their utility lies around their ability to hold different molecules in their pores. Their major application is in forming a base for making pigments. These particles can be converted into coloured particles by dyeing with basic, acidic, reactive, disperse or any other form of dyes suitable for dyeing textile fibres or precipitating pigmentary materials in these pores by carrying out the reaction in side the pore.

Polymeric pigment particles of the present invention made by using reactive dves are non- toxic and could be used for colouring food products or pharmaceutical preparations.

These can find applications in colouring plastics without any adverse effect on their properties. For example these pigments could be successfully used for blending with several commercial polymers such as polyethylene, polypropylene, polystyrene without any dispersing aid. These may be specially prepared from monomers, which have identical solubility parameter as that of the polymer in which they are desired to be added thus increasing their compatibility. In processes such as rotational moulding which are known to be zero shear processes, the dispersion of the colour was very uniform and the properties of the plastics remained substantially unaffected as seen from Table 2 The tensile strength, the elongation at break and the uniformity of colour were reasonably unaffected even when pigments were simply blended with the powders prior to rotational molding.

Table 2 :

Effect Of Polymeric Pigment in LLDPE

On Physical Properties

For Rotational Molding

As can be seen , the tensile strength of the plastic is not significantly altered by the presence of as much as 1% polymeric pigment which is more than adequate for saturating the colour of the plastic. % elongation is , how ever affected on pigment loading beyond 2%.

Claims

Claims :

1. A process for manufacture of micro-porous microsphers of sub-micron size of polymers which are suitable for conversion to polymeric pigments comprising,

i. Mixing micro-porosity generating agent(s) with the monomer(s) and/ or additives for some functional groups; ii. Emulsifying the mix obtained at the end of step I, in water with the help of emulsifying agent(s) to give homogenous emulsion, or making micro suspension of the said mix in water or non-aqueous phase with the help of suspending agent(s); iii. Subjecting the said emulsion or the said suspension obtained at the end of step ii, to polymerizing and/or cross-linking reaction with addition of initiator to form the micro-porous microsphers of the polymer; iv. Removing the non-polymerizable micro-porosity generating agent from the reaction mass al the end of step (Iii) when the reaction is complete; v. Coagulating the micro-porous microspheric polymer particles in the reaction mass remaining after step (iv) by addition of polymer-coagulating agent(s) to the said reaction mass; vi. Separating the coagulated micro-porous microspheric polymer particles from the reaction mass, washing and drying for recovering the polymers formed in the form of micro-porous microsphers of submicron size.

2. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in claim 1 wherein, monomer used in step (I) is 70- 88 % by wt., micropores generating agent(s) 5-16 % by wt and crosslinking agent 15-20 % by wt. of total mix.

3. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in claim 1 or 2 wherein polymerization is carried out at 30 - 100 °C for ~ 7-8 hrs.

4. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1 or 3, wherein monomer used in step (I) is any monomer [which is polymerizable under suspension or emulsion polymerization] or mixture of one or more of such monomers.

5. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1- 4 wherein, one or more said monomer(s) taken at step (I) are chosen from a group of monomers normally commercially used for making polymers, such as styrene, acrylonitrile (ACN), methyl methacrylate (MMA), Non-ionics emulsifiers such as NYP EO condensates, EO PO Co- or Block Copolymers, castor oil derivatives (40 moles EO/ mole Castor Oil), vegetable oil derivatives, silicones, fluorocarbons condensed with EO or EO/ PO; Gemini or hybrid surfactants

6. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1- 5, wherein said additives taken at step (I) for functional groups form 0 - 20 % by wt. of said monomer taken in step (I) for making the said mixture.

7. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1- 6, wherein said additives taken for functional groups at step (I) form 0 - 20 % by wt. of said monomer taken in step (I) for making the said mixture.

8. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1- 7, wherein amount of said aqueous phase water, in emulsificatlon is 50 -100 % of monomer and porosity generating agent mix.

9. A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1- 8 wherein, the amount of said emulsifiers, is 0.1 - 10 % by wt on aqueous phase.

10.A process for manufacture of micro-porous Microspheres of sub-micron size of polymers as claimed in any claim 1- 9 wherein, said additives taken for functional groups at step (l)are chosen from a group of monomers having such functionality as carboxylic, amine, quaternary, amide, allyl chloride, hydroxyl, secondary hydroxyl. primary hydroxyl.

11. A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 10 wherein, said additives taken for functional groups at step (I) are preferably chosen from a group of monomers such as acrylic acid, methacrylic acid, HEMA, GMA, AM, AMPS, SSA, SPME. [Strong base Amine type or their precursors such as VBC, CHPMA, ]

12.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1-11 wherein, mixture of monomers comprise (a).styrene 60 - 70 % by wt. and (b) acrylonitrile (ACN) 30 - 40 % by wt. and (c) with 10 % acrylic acid as a functional monomer and (d) DVB as cross linking agent 5-15 % by wt. of said monomer taken in step (I) for making the said mixture.

13.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 12 wherein, cross-linking agents preferable amount is 15 - 20 % of the monomer mix chosen from group of compounds such as

DVB, EDMA, or any other cross linking agent such as polyfunctional acrylates or methacrylates 14.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 13 wherein, crosslinking agents are used from 0.1 - 100 % by wt of total monomer mix.

15. A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 14 wherein, crosslinking agents are used from 15 - 100 % by wt of total monomer mix.

16. A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 15 wherein, micro-porosity generating agents are selected from group of compounds from any of the 4 types a) blowing agents such as propellents chosen from pentane, fluorocarbons, azobis iso-butyronltrile, azodicarbonamide, which blow off in to vapors on heating to 120 - 180 °C b) solid particulate material that dissolves in acid or alkali, such as calcium carbonate or sodium bi carbonate but are insoluble in monomers and polymers. c) non-crosslinkable polymer such as polystyrene, that dissolves in monomer and insoluble in polymers d) solvents which are solvents for monomers and non-solvents for polymers.

17 A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 16 wherein, micro-porosity generating agents are selected from group of compounds such as aliphatic or aromatic solvents; primary, secondary or tertiary alcohols that stay unpolymerized in polymerization process and leaves the microporous microsphers system on vaporization or on extraction with solvent and are preferably partially water soluble and having low boiling point or forming an azeotrope with water.

18.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 17 wherein, micro-porosity generating agents are selected from group of solvents such as tetrahydronaphthalenes, 2-ethyl hexanol, cyclohexanol, lauryl alcohol, Cι₂.₂₂ alcohol or a mixture thereof.

19.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 18 wherein, emulsifiers, are selected from group of anionic and/or nonionic surface active agents such as SLS, DDBS, soaps of different fatty acids or combinations thereof, naphthalinic sulphonate 0.1 - 10 % by wt on monomer and combinations thereof, Ger.iini surfactants of any type and nonionic surfactants, preferably from sorbitol mono-oleate, sodium lauryl sulfate .

20.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 19 wherein, suspending agents are selected from group of protective colloids such as polyvinyl alcohol, carboxymethyl cellulose, hydroxy ethyl cellulose, starch, lignin, gelatin chlorinated rubber from .05 to 5% on the weight of the suspension medium.

21.A process for manufacture of micro-porous microsphers of sub-micron size of polymers as claimed in any claim 1- 20 wherein, coagulating agents are selected from group of electrolytes, poly-electrolytes such as sodium chloride, sulfate, alum, cationic or anionic polyelectrolytes.

22.A process for manufacture of micro-porous microsphers of sub-micron size of polymers substantially as herein described in text and in examples.

23. A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process of our claims 1 to 22 above by following procedure described here, comprising

(i) preparation of solution of colouring compounds or soluble Leuco compounds which develop colours on oxidation, or soluble reactive dyes or soluble component of colouring compounds which form an insoluble colour on subsequent contact with its colour forming coupling component in solution, in solvents such as water, alcohol at required pH;

(ii) Soaking the said MPMS polymer particles in the solution for 30 - 60 minutes, at 20 - 150°C under pressure if necessary;

(iii) Separating the soaked particles obtained at the end of step (iii), washing, drying; to obtain the coloured polymeric pigment particles, (iv) soaking the dry particles obtained at the end of step (iii) in a coupling component when a pigment or a dye is required to be synthesized inside the pores of the pigmentary particle or, only when second component of the colouring compound is required to develop the colour, in said solution of the second component prepared in step (iii) for 30 - 60 minutes at 0 - 150 0C under pressure when required;

(v) Separating the soaked particles obtained at the end of step (vi), drying, washing, and drying; to obtain the coloured polymeric pigment particles.

24. A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process of our claims 1 to 22 above, colouring compounds are selected from group consisting of water / alcohol soluble dyes such as direct dyes, acidic dyes, basic dyes, fluorescent dyes.

25. A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process , as claimed in claim 1-22 wherein, colouring compounds are selected from group consisting of basic dye, then the polymer particles are selected from those having acidic functional polymers (MPMS A.)

26 A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process, as claimed in claim 1-22 wherein, colouring compounds are selected from group consisting of reactive dye, then the MPMS polymer particles are selected from those having appropriate functional polymers.

27 A process for manufacturing coloured polymeric pigment particles of submicron size, from miproporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process, as claimed in claim 1-22 wherein, if colouring compounds are selected from group consisting of reactive dyes, such as having β-sulphato ethyl sulphones, then the MPMS polymer particles are selected from those having hydroxyl functional groups.

28 A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process, as claimed in claim 1-22 wherein, colouring compounds are selected from group consisting of reactive dyes such as or anionic or cationic dyes, particularly when MPMS polymer particles have functional group that supports reaction.

29 A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process, as claimed in claim 1-22 wherein, colouring compounds are selected from group consisting of water soluble Leuco compounds of vat dyes, of alizarin, quinizarin or anilines that develop colour on oxidation on contact with air. 29 A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process of our accompanying application, as claimed in claim 1 wherein, colouring compounds are selected from group consisting of water / alcohol soluble components of dyes such as Naphthol of diazo dyes, mordents of mordant dyes, inorganic pigment components such as lead salts such as lead nitrate precipitated with chromate forming lead chromate, iron salts such as ferric formate or chloride forming iron oxide phthalogens forming phthalocyanine, that develop colour on subsequent contact with the corresponding coupling / colour forming component.

30 A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process of our accompanying application, as claimed in any one of the claims, claim 1-22 wherein, the dye bath is exhausted with addition of salt. Or any other water soluble inorganic solid

31 A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process of our accompanying application, as claimed in any one of the claims, claim 1-22 wherein, the drying of the washed coloured polymeric pigment particles is done under vacuum [1 -10 mm Hg] at 50 -80 °C.

32. A process for manufacturing coloured polymeric pigment particles of submicron size, from microporous microspherical (MPMS) polymer particles of submicron size, with or without functional groups, prepared by the process , substantially as herein described in the text and in the examples.