Claims:We claim

1. Microcapsule system comprising microcapsules compatible with both water and organics encapsulating hydrophobic content at >80% to 99% yield as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine.

2. Microcapsules system as claimed in claims 1 wherein the hydrophobic content include selectively saturated or unsaturated oil, wax of natural or synthetic origin and mixtures thereof preferably a phase changing material (PCM) selected from phase changing temperature range 5 – 40 deg C.

3. Microcapsules system as claimed in anyone of claims 1 or 2 wherein said microcapsules include latent heat storage material based core for effective management of temperature of the surface and compatible with putty or paint.

4. Microcapsules system as claimed in anyone of claims 1 to 3 wherein said shell includes silanes.

5. Microcapsules system as claimed in anyone of claims 1 to 4 comprising hydrophobic content in amounts of 30 to 70 % by wt and shell including of polyepoxy resin crosslinked with hydrophobic polyamine 30 to 70 % by wt optionally including silanes in amounts of 0 to 35 % by wt of the microcapsule.

6. Microcapsules system as claimed in anyone of claims 1 to 5 which is obtained at ambient temperatures and free of catalyst and essentially free of formaldehyde and isocyanates.

7. Microcapsules system as claimed in anyone of claims 1 to 6 comprising of aqueous suspension of said microcapsules having range of solids from 10 to 40 % by wt and particle size ranging from 10 nm to 1 mm.

8. Microcapsules system as claimed in claim 7 wherein said aqueous suspension includes defoamers, biocides, cosolvents, thickeners, pH modifier, dispersing and wetting agents.

9. Microcapsules system as claimed in anyone of claims 1 to 8 optionally including surfactants in amounts of upto 0.5% by weight of the microcapsules and stabilizers upto 15% by weight of the microcapsules preferably less than 10% and even more preferably less than 5% by weight of the microcapsules wherein surfactants can be anionic, non-ionic or cationic and stabilizers can be cellulose derivatives (carboxymethyl cellulose, hydroxyethyl cellulose), polyvinyl alcohol and clays.

10. Microcapsules system as claimed in anyone of claims 1 to 9 wherein said microcapsule shell comprises polyepoxy resin, hydrophobic polyamine and organo silane having epoxy to amine ratio (by stoichiometry, 1:1.3 to 1:0.5 preferably 1:1, and optionally silica precursors and organosilanes 0 to 60% by weight preferably 10-40% by weight of the shell composition.

11. Microcapsules system as claimed in anyone of claims 1 to 10 wherein the microcapsules have ratio of core to shell comprise 30:70 to 70:30 preferably 50:50.

12. Microcapsules system as claimed in anyone of claims 1-11 wherein polyepoxy resin includes Lapox B11 (Diglycidyl ether of bisphenol A), Epoxy Novolac Resin, Epoxy solvent cut resin, liquid epoxy resin based on bisphenol-A, epoxy phenol Novolac resin having functionality 3.6, Bisphenol F type epoxy, epoxy resin of hydrogenated Bisphenol A, and bisphenol A/F epoxy resin with monofunctional reactive diluent preferably either an aromatic epoxy, or an aliphatic or cycloaliphatic epoxy;
wherein hydrophobic amine includes isophorone diamine, poly(oxypropylene) diamine, amine-epoxy adducts, dimer fatty acid modified amine adducts, polyamides, phenalkamine, polyether-amines preferably selected from dimer fatty acid modified amine adducts, amine terminated polyamides, epoxy-amine adducts, phenalkamine.

13. Microcapsules system as claimed in claim 10 wherein organo-silane includes Rx-Si(OR1)(4-x) and Si(O)(4-y)/2(OR1)y where R1= Me, Et, n-Pr, i-Pr, n-Bu, i-Bu,t-Bu; x=1,2,3 & y=0-4 (including fractions) preferably APTES (3-aminopropyl triethoxysilane) and TEOS.

14. Microcapsules system as claimed in anyone of claims 1 to 13 comprising hybrid microcapsules possessing inorganics in the range of 10 to 40 weight % on the shell having increased values of compressive strength compared to organic microcapsules.

15. Microcapsules system as claimed in anyone of claims 1 to 14 comprising said microcapsules having size range of 10 nm - 1000 nm or in the size range of 1 microns to 200 microns or in the size range of 200 microns to 1 mm.

16. A process for the manufacture of the microcapsules system as claimed in anyone of claims 1 to 15 comprising:
reacting in aqueous media said polyepoxy resin and said hydrophobic amine in a reactor in the presence of said hydrophobic core content under control in the temperature range of 250C to 850C such as to provide said microcapsules compatible with both water and organics and encapsulating the said hydrophobic content at 80% to 99% yield in reaction time of (<24 hours) free of any catalysts.

17. A process as claimed in claim 16 comprising:
a. adding water to the reactor with or without surfactants and stabilizers and raising the temperature to a temperature range of 25 to 85 0C preferably about 80°C;
b. adding epoxy polymer or hydrophobic polyamine and stirring involving impeller means for 10 minutes to 1 hours preferably about 1 hour at 100 to 500 RPM preferably about 300 RPM;
c. cooling to 25 to 600C preferably about 600C after obtaining homogeneous solution;
d. charging the hydrophobic content under stirring and continue stirring for a period of 10 minutes to 60 minutes preferably about 30 minutes;
e. charging the hydrophobic polyamine or epoxy polymer with or without inclusion of silanes to the reactor in 10 minutes to 60 minutes preferably about 30 minutes duration;
f. allowing the reaction to run under controlled temperature at 60°C to 80 0C for 1 to 6 hours to thereby obtain said microcapsules system comprising of microcapsules compatible with both water and organics encapsulating hydrophobic content at 80% to 99% yield as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine.

18. A process as claimed in claim 17 wherein said step f) comprises:
i. allowing the reaction to run at 60°C for 1 to 3 hour;
ii increasing the temperature to 70°C and maintaining it for 1 to 3 hours;
ii. increasing the temperature to 80°C and run it for 1 to 3 hours.

19. A process as claimed in anyone of claims 16 to 18 which is carried out involving optionally surfactants in amounts of only upto 0.5% by wt of the microcapsules and stabilizers of only upto 15 % by wt preferably less than 10% and even more preferably less than 5% by weight of the microcapsules.

20. A process as claimed in anyone of claims 17 to 19 comprising step of obtaining dried microcapsules compatible with both water and organics encapsulating hydrophobic content at 80% to 99% yield as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine following the additional steps of
i) cooling and filtering the mixture through filter means; and
ii) washing the capsules with hot water followed by drying in vacuum oven affording PCM encapsulated hybrid microparticles.

21. A process as claimed in anyone of claims 16 to 20 carried out selectively by varying the concentration of surfactants and by varying impeller tip speed during reaction for desired encapsulation efficiency and wherein the microcapsules can be prepared in the size range of 10 nm - 1000 nm or in the size range of 1 microns to 200 microns or in the size range of 200 microns to 1 mm.

22. Coating formulation including cement putty having temperature management attributes comprising:
coating formulation involving microcapsules system
comprising microcapsules encapsulating phase changing hydrophobic material as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine.

23. Coating formulation as claimed in claim 22 wherein the proportion of said coating formulation : microcapsules system vary in the selective range of 90:10 to 50:50 respectively.

24. Coating formulation as claimed in anyone of claims 22 or 23 wherein said encapsulated phase changing material is selected from oils (e.g. palm oil, castor oil), waxes (e.g. beeswax, paraffin), alkanes (e.g. n-hexadecane, n-tetradecane) and acids (stearic acid, palmitic acid).

25. Coating formulation as claimed in anyone of claims 22 to 24 which is cementitious coating formulation including cement putty having improved compressive strength in the range of 0.5 to 3 MPa with respect to conventional cement putty compressive strength in the range of 0.5 to 2 MPa.

Dated this the 4th day of June, 2019 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
IN/PA-199
, Description:Field of invention
The present invention relates to efficient encapsulation of hydrophobic core materials to create high yield and high strength, cement compatible microcapsules in aqueous media and a coating formulation involving the same.

Background
Microencapsulation is a process by which very tiny droplets or particles of liquid or solid material are surrounded or coated with a continuous film of polymeric material.
An important goal of the present day society is to reduce the requirement for energy and to utilize existing heat energy in a more rational way. Here, a particular concern is the improvement of energy-intensive systems, such as heating and cooling systems, which often have unsatisfactory efficiency. One approach to solve this problem is to increase the heat storage capacity of the liquid heat transfer medium through the addition of latent heat storage materials. Thus, a greater amount of energy can be transported using less pump energy and/or smaller pipe cross sections and smaller heat exchangers. A further advantage is the increased heat storage possibility in the overall system of pipelines and heat exchangers, such that it is often possible to dispense with further storage possibilities, such as additional containers or tanks. Recent states of the art towards the aforementioned goal are as follows:

US20060199011A1 relates to use of aqueous microcapsule dispersions with latent heat storage materials as capsule core and a polymer as shell, which are obtainable by heating an oil-in-water emulsion in which the monomers, free radical initiators and the latent heat storage materials are present as a disperse phase, where the monomer mixture comprises acrylic derivatives.
US5200236 teaches solid core particles encapsulated in a single coat of paraffin wax, the wax having a melting point of about 40° to about 50° C and a solids content of from 100 to about 35% at 40° C and from 0 to about 15% at 50° C. The paraffin coat may comprise 20 to 90% by weight of the particle and may be from 100 to 1,500 microns thick. The coat prolongs the time in which particles encapsulated therewith may remain active in aqueous environments.

CN101537331A 20090923 This prior patent discloses preparation of fire retardants ammonium polyphosphate containing epoxy resin-coated microcapsules by: (1) dispersing epoxy resin 1-4 g and curing agent 0.2-2 g in a solvent 50-100 mL; adding fire retardant ammonium polyphosphate and dispersing agent under stirring, stirring for 20-40 min, heating to 50-120°C, reacting for 1-8 h to obtain product; filtering, washing with water for several times, and drying at 100-130°C for 6-96 h to obtain the title product. The epoxy resin is one of bisphenol A-glycidyl ether resin, bisphenol F-glycidyl ether resin, etc. The curing agent is one of aliphatic Polyamine, aromatic polyamine or anhydride curing agent, such as ethylenediamine, diethylenetriamine, etc. The solvent is from methanol, acetone, etc. The dispersing agent is from sodium dodecyl sulfate, OP emulsifier or sodium dodecylsulfonate

DE214046119720330 The disclosure teaches solids and liquids encapsulation, using epoxy resins, by solutions of water-insoluble monomer in a solvent more hydrophilic than the monomer, dispersion of the solution and substrate in water, and addition of catalyst in a similar solvent. Thus, a soln. of 5 g Epikote 828 [25068-38-6] [Poly(Bisphenol A-co-epichlorohydrin)] in 15 ml acetone [67-64-1] is dispersed in 1 l. 5% aq. gelatin, the mixture combined with 20 ml xylene [1330-20-7], stirred 10 min, combined with a soln. of 4 g isophoronediamine-phenolic resin adduct in 15 ml MeCO2, and stirred to give 50-100 µm microcapsules of xylene.

US 20140073210 A1 teaches coated articles with microcapsules and other containment structures incorporating functional polymeric phase change materials wherein an article comprising a substrate, a first functional polymeric phase change material, and a plurality of containment structures that contain the first functional polymeric phase change material. The article may further comprise a second phase change material chemically bound to at least one of the plurality of containment structures or the substrate. The binder includes from 0.2 percent to 5 percent of silicon-containing epoxy polymer wherein amino groups are present from 0.1 percent to 20 percent. However no procedure is taught to form microcapsules. Epoxy, siloxane, amine, isocyanate etc. functional materials are used as the binder to bind microcapsules to the textile fibers.

US20070173154A1 This prior art deals with a coated article which includes a substrate and a coating covering at least a portion of the substrate. The coating includes a binder having a glass transition temperature in the range of -110° C. to -40° C. The coating also includes a set of microcapsules having sizes in the range of 1 micron to 15 microns, and at least one of the set of microcapsules is chemically bonded to either of, or both, the substrate and the binder.

US8835002B2 teaches water-dispersible core-shell microcapsules that are essentially free of formaldehyde. Also, oligomeric compositions of, and microcapsules obtained from, particular reaction products between a polyamine component and a particular mixture of glyoxal and a C4-6 2,2-dialkoxy-ethanal in presence of acid catalyst. These compositions and microcapsules can be used as part of a perfuming composition or of a perfumed consumer product.

JP 2005131513A 20050526 discloses manufacture of the microcapsules by dispersing hydrophobic core substances in aq. media containing H2O-sol. surfactants and adding H2O-sol. compounds. to the media, R1(CH2CH2O)nXR2 (I; R1 = C5-25 aliphatic or aromatic hydrophobic group; R2 = 300-100,000-Mw polyamine or polycarboxylic acid group; n = 3-85; X = direct link, group derived from amino-, imino-, and/or carboxy-reactive group) are used as the H2O-sol. surfactants, compound having epoxy or episulfide group are used as the H2O-soluble compounds, and the shells are formed by reaction between I and the H2O-soluble compound. The reaction mixture was kept at 30° for 2 h, aged at 70°, and cooled to give a microcapsule dispersion showing particle size 65.0 µm, shell thickness 3.12 µm, and good capsule strength.

Liu, X. et al (Surface and Coatings Technology, 206(23), pp.4976-4980.) reported the preparation of the capsules using interfacial polymerization of liquid epoxy resin with ethylene diamine (EDA) forming the shell and liquid epoxy resin forming the core. A water-soluble diamine (EDA) is used at less than stoichiometric content to liquid epoxy so as to encapsulate the liquid epoxy keeping free oxirane functionality. External surfactants such as Arabic gum and Tween 80 have been used for the interfacial polymerization. This technique does not employ any surfactant like shell material and does not lead to a high yield of encapsulation of hydrophobic liquids such as oils.
In another report Lian, Q. et al (J. Mater. Chem. A 2017) disclosed that solid-solid PCMs were prepared using octadecanethiol grafted onto allyl functional epoxy resin followed by ring opening polymerization of the epoxy groups.

Whereas Pascu, O. et al employed interfacial polymerization of an epoxy resin and potassium salt of decandioic acid and benzenetricarboxylic acid in presence of tetrabutylammonium hydrogen sulfate catalyst for the synthesis of microcapsules in toluene and water mixture (Polymer International. 2008; 57:995-1006). The reaction requires catalyst, elevated temperature (60 deg C) and long reaction times (5 days).

He, H. et al (Renew. Energy 2015, 76, 45–52) employed vacuum impregnation method to incorporate polynary fatty acid eutectic mixture into sludge-clay ceramic composite phase change materials and its applications in building energy conservation. Here, adsorption of the fatty acid mixture took place on the porous ceramic material and an epoxy resin was used to cap the composite material to avoid leakages.

Jeong, S.G. et al (Energy Convers. Manag. 2012, 64, 516–521) prepared a composite material by entrapping PCM in an epoxy resin and amine hardener matrix for wood-based flooring application. All 3 liquids are mixed and allowed to cure as moulds.

Kathalewar, M. et al in their publication (Prog. Org. Coatings 84, 79–88 2015) described the study of effect of molecular weight and structures of phenalkamine curing agents on the curing, mechanical, thermal and anticorrosive properties of epoxy based coatings. Liquid epoxy and phenalkamine were used to prepare anti corrosive coatings. The study revealed that high molecular weight phenalkamines resulted in faster surface drying due to rapid molecular weight build-up. The anticorrosive performance also improved as indicated by higher modulus and electrochemical potential values.

M. Ochi et al; (J. Polym. Sci. B: Polym Phys 39: 1071–1084, 2001) have reported synthesis of several kinds of organic–inorganic hybrids from an epoxy resin and a silane alkoxide with a primary amine type curing agent or tertiary amine curing catalyst. In the hybrid systems cured with the primary amine type curing agent, the storage modulus in the high temperature region increased, and the peak area of the tan d curve decreased. Moreover, the mechanical properties were improved by the hybridization of small amounts of the silica network. However, these phenomena were not observed in the hybrid systems cured with the tertiary amine catalyst. The hybrids with the primary amine showed a homogeneous microstructure in transmission electron microscopy observations, although the hybrids cured with the tertiary amine showed a heterogeneous structure.

In another report Feczkó, Tivadar et al (Feczko et al 2015 PGMA-REAL.pdf http://real.mtak.hu/id/eprint/26496) described preparation of macroporous sorbent beads of large and small sizes by the AIBN-initiated suspension radical polymerization of glycidyl methacrylate and ethylene dimethacrylate monomers in the presence of an inert porogen. The large and small microspheres were loaded with paraffin and cetyl alcohol PCMs (phase change materials), respectively, and coated with silica nanoparticles after sol-gel synthesis of trimethoxy(methyl)silane hydrolysate. The energy storing capacity of the form-stabilized PCM containing composite particles was monitored by differential scanning calorimetry. Paraffin and cetyl alcohol content of the microcapsules was 42.9 % and 48.9 %, respectively.

In a journal publication (Journal of Macromolecular Science R, Part B: Physics, 50:975–987, 2011, https://doi.org/10.1080/00222348.2010.497124) Songqi, Ma et al disclosed polysiloxane capped with silane coupling agent, epoxide, and imino groups (AGPMS) was prepared by ring-opening reaction of 3-glycidoxypropyl poly(methylsilane) (GPPMS) with ? -aminopropyltriethoxysilane (APTES) to modify an epoxy resin. All the samples were cured under the same conditions using DDM (Diaminodiphenylmethane) as curing agent. The thermosetting blends containing AGPMS up to 12 wt % were prepared.

In Polymer Bulletin (Heidelberg, Germany 2017, 74(2), 359-367. DOI:10.1007/s00289-016-1718-z) Wei, Kun et al stated a series of novel epoxy polymer shell microcapsules with n-tetradecane and dimethylbenzene as binary core materials which are successfully synthesized via interfacial polymerization. Dimethylbenzene was used as the solvent for epoxy and n-tetradecane. Results showed that the micro-PCMs had relatively spherical profiles and smooth surfaces with diams. ranging from 10 to 70 µm. The epoxy shell successfully encapsulated the binary core.

Farhadyar et al (Iranian Polymer Journal 14 (2), 2005, 155-162) revealed the preparation of organic-inorganic hybrid coating based on epoxy resin and tetraethoxysilane. These hybrid networks possess excellent optical transparency and nano scale microphase separation. These hybrid materials can be used for coating aluminum alloy (AA) substrates. The Chemical structure of obtained network affects morphology of the coating. So, morphology of the fractured surface was observed by scanning electron microscopy (SEM). It is found that the average diameter of particles is 167 nm, which indicates the transparency of the hybrid system. TGA results show that cross-linking between the epoxy resin and silica increases the thermal stability of the system.

In a Conference Proceedings MATRIB 2003 Jelena Macan et al presented epoxy resin wherein diglycidyl ether of bisphenol A (DGEBA) and poly(oxypropylene) diamine Jeffamine D230 was modified by adding modified silicon alkoxide, 3-glycidyloxypropyltrimethoxysilane (GLYMO), in the reaction mixture. Inorganic phase inside the organic matrix was formed by sol-gel process, which included hydrolysis and condensation of alkoxy groups of GLYMO. Epoxy groups of GLYMO were found to react only with primary amine. The inorganic phase caused a steric hindrance to full crosslinking of epoxy groups. The organic chains were also immobilized by the inorganic phase, and its presence improved the temperature stability of hybrid materials.
Jeffamine D230
Chang KC et al. [J. Nanosci Nano technol. 2008 Jun; 8(6):3040-9] studied effect of amino-modified silica nanoparticles on the corrosion protection properties of epoxy resin-silica hybrid materials wherein a series of organic-inorganic hybrid materials consisting of epoxy resin frameworks and dispersed nanoparticles of amino-modified silica (AMS) that were successfully prepared. The crosslinker for epoxy resin is T403 (polyetheramine) which is water soluble amine. The AMS nanoparticles were synthesized by carrying out the conventional acid-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) in the presence of 3-aminopropyl)-trimethoxysilane (APTES) molecules. Subsequently, a series of hybrid materials were prepared by performing in-situ thermal ring-opening polymerization reactions of epoxy resin in the presence of as-prepared AMS nanoparticles and raw silica (RS) particles. Characteristics of Epoxy-silica hybrid materials with AMS nanoparticles were evaluated with RS particles.

Wang et al. (Journal of Microencapsulation Micro and Nano Carriers Volume 23, 2006 - Issue 1 Pages 3-14) disclosed preparation of spherical silica microcapsules containing phase-change material (PCM) by the sol-gel method in O/W emulsion. This is the first time that inorganic encapsulation of PCM with core/shell structure has been studied. The results of this synthesis revealed that micron size (4?~?8?µm) silica microspheres encapsulating n-pentadecane can be successfully created from acidic solutions ([H+]?=?1.44?N) by using cationic surfactants as the emulsifiers.

Traversal of the prior art indicates that there is an urgent need to develop a smarter technique wherein microcapsules could be prepared in aqueous environment, should be capable of incorporating hydrophobic materials (such as waxes, oils, other hydrophobic substances, their combinations) with a high yield >80%, could be prepared under ambient conditions without requirement of catalyst, should be essentially isocyanate and formaldehyde free and compatible with both water and organic solvent

Objective of the Invention
Primary objective of the present invention is to develop a microcapsule system which can encapsulate hydrophobic material such as waxes, oils, other hydrophobic substances, their combinations with a high yield.
Another objective of the present invention is to develop a microcapsule system which would help effective management of temperature of the surface when applied on the same as putty or paint.
Another objective of the present invention is to develop microcapsules wherein the microcapsules will be high strength.
Another objective of the present invention is to develop microcapsules wherein the microcapsules would be cement compatible
Another objective of the present invention is to develop microcapsules wherein the microcapsules should be compatible with both organic solvent and water.
Another objective of the present invention is to develop microcapsules wherein microcapsules would be based on epoxy resin and water insoluble amines.
Another objective of the present invention is to develop microcapsules wherein microcapsules could be made further robust by incorporation of silanes on the coating.
Another objective of the present invention is to develop microcapsules wherein the method of preparation of microcapsules would be at ambient temperature.
Another objective of the present invention is to develop microcapsules wherein the method of preparation of microcapsules would be in water.
Another objective of the present invention is to develop microcapsules wherein the method of preparation of microcapsules would be catalyst free.
Another objective of the present invention is to develop microcapsules wherein the method of preparation of microcapsules would be essentially free of formaldehyde and isocyanates.
Another objective of the present invention is to develop microcapsules wherein the method of preparation of microcapsules would be single step.
Another objective of the present invention is to develop microcapsules wherein the method of preparation of microcapsules would be requiring lesser quantity of surfactant and stabilizers.
Another objective of the present invention is to provide a coating formulation comprising the encapsulated microcapsules.

Summary of the invention
The prime aspect of the present invention is directed to provide microcapsule system comprising microcapsules compatible with both water and organics encapsulating hydrophobic content at 80% to 99% yield as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine.

Another aspect of the present is directed to provide microcapsules system wherein the hydrophobic content includes selectively saturated or unsaturated oil, wax of natural or synthetic origin and mixtures thereof preferably a phase changing material (PCM) selected from phase changing temperature range 5 – 40 deg C.

A still further aspect of the present invention is a microcapsules system wherein said microcapsules include latent heat storage material based core for effective management of temperature of the surface and compatible with putty or paint.

Another aspect of the present invention is directed to provide microcapsules system wherein said shell includes silanes.

Yet another aspect of the present invention is directed to provide microcapsules system comprising hydrophobic content in amounts of 30 to 70 % by wt and shell including of polyepoxy resin crosslinked with hydrophobic polyamine 30 to 70 % by wt optionally including silanes in amounts of 0 to 35 % by wt of the microcapsule.

Yet another aspect of the present invention is directed to microcapsules system which is obtained at ambient temperatures and free of catalyst and essentially free of formaldehyde and isocyanates.

Another aspect of the present invention is directed to microcapsules system comprising of aqueous suspension of said microcapsules having range of solids from 10 to 40 % by wt and particle size ranging from 10 nm to 1 mm.

Yet another aspect of the present invention is directed to microcapsules system wherein said aqueous suspension includes range of defoamers, biocides, cosolvents, thickeners, pH modifier, dispersing and wetting agents.

A further aspect of the present invention is directed to provide microcapsules optionally including surfactants in amounts of upto 0.5% by weight of the microcapsules and stabilizers upto 15% by weight of the microcapsules preferably less than 10% and even more preferably less than 5% by weight of the microcapsules wherein surfactants can be anionic, non-ionic or cationic and stabilizers can be cellulose derivatives (carboxymethyl cellulose, hydroxyethyl cellulose), polyvinyl alcohol and clays.

Further aspect of the present invention is directed to provide microcapsules system wherein said microcapsule shell comprises polyepoxy resin, hydrophobic polyamine and organo silane having epoxy to amine ratio (by stoichiometry, 1:1.3 to 1:0.5 preferably 1:1, and optionally silica precursors and organosilanes 0 to 60% by weight preferably 10-40% by weight of the shell composition.

Another aspect of the present invention is directed to provide microcapsules system wherein the microcapsules have ratio of core to shell comprise 30:70 to 70:30 preferably 50:50.

Yet another aspect of the present invention is directed to provide microcapsules wherein polyepoxy resin includes Lapox B11 (Diglycidyl ether of bisphenol A), Epoxy Novolac Resin, Epoxy solvent cut resin, liquid epoxy resin based on bisphenol-A, epoxy phenol novolac resin having functionality 3.6, Bisphenol F type epoxy, epoxy resin of hydrogenated Bisphenol A, and bisphenol A/F epoxy resin with monofunctional reactive diluent preferably either an aromatic epoxy, or an aliphatic or cycloaliphatic epoxy;
wherein hydrophobic amine includes isophorone diamine, poly(oxypropylene) diamine, amine-epoxy adducts, dimer fatty acid modified amine adducts, polyamides, phenalkamine, polyether-amines preferably selected from dimer fatty acid modified amine adducts, amine terminated polyamides, epoxy-amine adducts, phenalkamine.

Further aspect of the present invention is directed to provide microcapsules system wherein organo-silane includes Rx-Si(OR1)(4-x) and Si(O)(4-y)/2(OR1)y where R1= Me, Et, nPr, i-Pr, n-Bu, i-Bu,t-Bu; x=1,2,3 & y=0-4 (including fractions) preferably APTES (3-aminopropyl triethoxysilane) and TEOS.

Yet further aspect of the present invention is directed to provide microcapsules system comprising hybrid microcapsules possessing inorganics in the range of 10 to 40 weight % on the shell and increased values of compressive strength compared to organic microcapsules.

Another aspect of the present invention is directed to provide microcapsules system comprising said microcapsules having size range of 10 nm - 1000 nm or in the size range of 1 microns to 200 microns or in the size range of 200 microns to 1 mm.

Yet another aspect of the present invention is directed to provide a process for the manufacture of the microcapsules system comprising:
reacting in aqueous media said polyepoxy resin and said hydrophobic amine in a reactor in the presence of said hydrophobic core content under control in the temperature range of 250C to 850C such as to provide said microcapsules compatible with both water and organics and encapsulating the said hydrophobic content at 80% to 99% yield in reaction time of (<24 hours) free of any catalysts.

Yet another aspect of the present invention is directed to provide a process comprising:
a. adding water to the reactor with or without surfactants and stabilizers and raising the temperature to a temperature range of 25 to 85 0C preferably about 80°C;
b. adding epoxy polymer or hydrophobic polyamine and stirring involving impeller means for 10 minutes to 1 hours preferably about 1 hour at 100 to 500 RPM preferably about 300 RPM;
c. cooling to 25 to 600C preferably about 600C after obtaining homogeneous solution;
d. charging the hydrophobic content under stirring and continue stirring for a period of 10 minutes to 60 minutes preferably about 30 minutes;
e. charging the hydrophobic polyamine or epoxy polymer with or without inclusion of silanes to the reactor in 10 minutes to 60 minutes preferably about 30 minutes duration;
f. allowing the reaction to run under controlled temperature at 60°C to 80 0C for 1 to 6 hours to thereby obtain said microcapsules system comprising of microcapsules compatible with both water and organics encapsulating hydrophobic content at 80% to 99% yield as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine.

Further aspect of the present invention is directed to provide a process wherein said step f) comprises:
i. allowing the reaction to run at 60°C for 1 to 3 hour;
ii increasing the temperature to 70°C and maintaining it for 1 to 3 hours;
ii. increasing the temperature to 80°C and run it for 1 to 3 hours.

Yet further aspect of the present invention is directed to provide a process which is which is carried out involving optionally surfactants in amounts of only upto 0.5% by wt of the microcapsules and stabilizers of only upto 15 % by wt preferably less than 10% and even more preferably less than 5% by weight of the microcapsules.

Another aspect of the present invention is directed to provide a process comprising step of obtaining dried microcapsules compatible with both water and organics encapsulating hydrophobic content at 80% to 99% yield as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine following the additional steps of
i) cooling and filtering the mixture through filter means; and
ii) washing the capsules with hot water followed by drying in vacuum oven affording PCM encapsulated hybrid microparticles.

Another aspect of the present invention is directed to a process carried out selectively by varying the concentration of surfactants and by varying impeller tip speed during reaction for desired encapsulation efficiency and wherein the microcapsules can be prepared in the size range of 10 nm - 1000 nm or in the size range of 1 microns to 200 microns or in the size range of 200 microns to 1 mm.

Further aspect of the present invention is directed to provide coating formulation including cement putty having temperature management attributes comprising:
coating formulation involving microcapsules system
comprising microcapsules encapsulating phase changing hydrophobic material as core material and a shell including of polyepoxy resin crosslinked with hydrophobic polyamine.

Another aspect of the present invention is directed to provide coating formulation wherein the proportion of said coating formulation : microcapsules system vary in the selective range of 90:10 to 50:50 respectively.

Yet another aspect of the present invention is directed to provide coating formulation wherein said encapsulated phase changing material is selected from oils (e.g. palm oil, castor oil), waxes (e.g. beeswax, paraffin), alkanes (e.g. n-hexadecane, n-tetradecane) and acids (stearic acid, palmitic acid).

Yet further aspect of the present invention is directed to coating formulation which is cementitious coating formulation including cement putty having improved compressive strength in the range of 0.5 to 3 MPa with respect to conventional cement putty compressive strength in the range of 0.5 to 2 MPa.

Details of the Invention

Microcapsules have been prepared (isocyanate and formaldehyde free) in water incorporating hydrophobic oils and waxes at 80% to >99% yield. The capsules can be prepared at 25 to 85 deg C requiring low reaction times (<24 hours) without catalysts.
The synthesis of hydrophobic oils and waxes encapsulated polymer silica hybrid shell, where the shell is comprised of, epoxy polymer (aromatic/aliphatic), amine (cyclo, aromatic, long chain aliphatic), silica, and/or silsesquioxane of formula Rx-SiO(4-x)/2 R = aliphatic long chain, Vinyl, aromatic, aliphatic amine. This inorganic/ hybrid modification along with polymer gives advantage of improved compatibility with inorganic cementitious construction chemicals improving the mechanical property of the cementitious coating. Furthermore these capsules can be synthesized in broad temperature range 25 to 85 °C with or without requirement of any catalyst.
Either the epoxy or the amine component can be taken in the reactor first and the other ingredient can be added dropwise to conduct a controlled reaction.
The size of the capsules can be controlled by varying the concentration of the surfactants and by varying the impeller tip speed during reaction. The capsules can be prepared in the size range of 10 nm - 1000 nm or in the size range of 1 micron to 200 microns or in the size range of 200 microns to 1 mm.
Optionally surfactant can be added in amounts of upto 0.5% wherein surfactants can be anionic, non-ionic or cationic and stabilizers can be added upto 15% by weight of the microcapsules preferably less than 10% and even more preferably less than 5% by weight of the microcapsules wherein stabilizers can be cellulose derivatives (carboxymethyl cellulose, hydroxyethyl cellulose), polyvinyl alcohol and clays to the reactor.

The examples below are intended to illustrate the invention in more detail. Unless stated otherwise, the percentages given are percentages by weight.

Examples for the preparation of epoxy amine microcapsules
Example-1
Encapsulation of Phase changing material (PCM 28), having 28 deg C melting points by Epoxy Phenalkamine system
RM F=1(%)
Water 66.904
PVA-124 3.496

Lapox B11 7.2
PCM-28 12.5

Phenalkamine PPA 7041 5.3

Water 4.6
100

Process for encapsulation PCM-28 comprises the steps of
a) Adding DM Water to the reactor and raising the temperature to 80°C;
b) adding Polyvinyl alcohol (PVA-124 from Kuraray) as a stabilizer and stirring for 1 hour at 300 RPM;
c) cooling to 600C once homogeneous solution is obtained;
d) charging Lapox B11 (Diglycidyl ether of bisphenol A) and PCM-28 one after another under stirring and continue stirring for 30 minutes;
e) charging PPA 7041 to the reactor in 30 minutes duration (PHENALKAMINE EPOXY HARDENER);
f) allowing the reaction to run at 60°C for 1 hour 30 minutes;
g) increasing the temperature to 70°C and maintaining it for 1 hour;
h) increasing the temperature to 80°C and run it for 1 hour;
i) filtering batch at 80°C.
j) washing the capsule with hot water followed by drying in vacuum oven providing PCM- 28 containing microcapsules.
Yield: ~100%.
Colour of the capsules: Yellow

Example 2
Encapsulation of Palm oil by Epoxy Phenalkamine system
RM F=1
Water 66.904
PVA-124 3.496

Lapox B11 7.2
Palm oil 12.5

PPA 7041 5.3
Water 4.6
100

Process for encapsulation of palm oil comprises the steps of
I. Adding DM Water to the reactor and raising the temperature to 80°C;
II. adding Polyvinyl alcohol (PVA-124) and stirring for 1 hour at 300 RPM;
III. cooling to 600C once homogeneous solution is obtained;
IV. charging Lapox B11 (Diglycidyl ether of bisphenol A) and palm oil one after another under stirring and continue stirring for 30 minutes;
V. charging PPA 7041 to the reactor in 30 minutes duration;
VI. allowing the reaction to run at 60°C for 1 hour 30 minutes;
VII. increasing the temperature to 70°C and run it for 1 hour;
VIII. increasing the temperature to 80°C and run it for 1 hour;
IX. filtering batch at 80°C; and
X. washing the capsule with hot water followed by drying in vacuum oven providing palm oil encapsulated microcapsules.
Yield: ~100%.
Colour of the capsules: Yellow

Example3

Encapsulation of Palm oil and PCM mixture by Epoxy Phenalkamine system
RM F=1
Water 66.904
PVA-124 3.496

Lapox B11 7.2
Palm oil 6.25
PCM 28 6.25

PPA 7041 5.3
Water 4.6
100

Process for encapsulation of palm oil and PCM mixture comprises the steps of

a. Adding DM Water to the reactor and raising the temperature to 80°C;
b. adding Polyvinyl alcohol (PVA-124) and stirring for 1 hour at 300 RPM;
c. cooling to 600C once homogeneous solution is obtained;
d. charging Lapox B11 (Diglycidyl ether of bisphenol A) and palm oil and PCM-28 one after another under stirring and continue stirring for 30 minutes;
e. charging PPA 7041 to the reactor in 30 minutes duration (PHENALKAMINE EPOXY HARDENER);
f. allowing the reaction to run at 60°C for 1 hour 30 minutes;
g. increasing the temperature to 70°C and maintaining it for 1 hour;
h. increasing the temperature to 80°C and run it for 1 hour;
i. filtering batch at 80°C;
j. washing the capsule with hot water followed by drying in vacuum oven providing palm oil and PCM- 28 containing microcapsules.

Yield: ~100%.
Colour of the capsules: Yellow

Examples 4 to 7: Hybrid Micro Encapsulation of Hydrophobic Materials

Example 4
RM F=1
Water 62.38
PVA-124 (polyvinyl alcohol) 3.27
Lapox B11 6.72
PCM 28 11.67
TEOS (Tetraethyl ortho silicate) 7.93
PPA7041 2.52
APTES (3-aminopropyl triethoxysilane) 1.68
Nonionic alcohol ethoxylate 0.1
IPA 3.73

Example 5
RM F=1
water 26.94
8% PVA-124 aqueous solution 44.1
Lapox B11 7.26
PCM 28 12.61
PPA 7041 2.72
APTES 1.82
TEOS 0
IPA 3.53
IPA 0.50
water 0.50

Example 6
RM F=1
water 25.83
8% PVA-124 Soln 42.28
Lapox B11 6.97
PCM 28 12.09
PPA 7041 2.61
APTES 1.74
TEOS 4.11
IPA 3.39
IPA 0.48
water 0.48

Example 7
RM F=1
water 24.81
8% PVA-124 Soln 40.61
Lapox B11 6.69
PCM 28 11.62
PPA 7041 2.51
APTES 1.67
Metasil 40 7.9
IPA 3.25
IPA 0.46
water 0.46

Preparation process of hybrid microcapsules: (Examples 4 to 7)
a. Adding DM Water to the reactor and raising the temperature to 80°C;
b. adding PVA-124 and stir for 1 hour at 300 RPM;
c. cooling to 600C once homogeneous solution is obtained;
d. charging Lapox B11, PCM-28 and TEOS (Tetraethyl ortho silicate)/Metasil-40 (oligomerized TEOS) one after another under stirring and continuing stirring for 30 minutes;
e. weighing PPA 7041, APTES (3-aminopropyl triethoxysilane) and IPA (isopropyl alcohol) in a separate flask and heating at 50°C for 10 minutes under stirring to obtain a homogeneous solution;
f. adding this amine solution to the reactor in 30 minutes duration;
g. allowing the reaction to run at 60°C for 1 hour 30 minutes;
h. increasing the temperature to 70°C to run it for 1 hour;
i. increasing the temperature to 80°C to run it for 3 hour;
j. optionally adding nonionic alcohol ethoxylate to the reactor;
k cooling the reactor to 60°C and leaving it at this temperature for 4 hours for ageing;
l. cooling the reaction to room temperature and filtering the mixture through Whatman filter paper; and
m. washing the capsule with hot water followed by drying in vacuum oven.
Yield: 80-99%
Colour: Light Yellow, Fine Powder

Testing of the capsules
The capsules were subjected to differential scanning calorimetry and melting point (Tm), crystallization temperature (Tc) and latent heat of melting displayed by the core material were recorded as shown in Table 1.
Table 1: Thermal analysis of the microcapsules

Sample
Tm
Tc
?H
Example 1 24?C 27?C 90 J/g
Example 4 23 ?C 27 ?C 95 J/g

Examples for the preparation of thermal management coating using the epoxy amine microcapsules
Temperature reduction profiles
The cooling effect of the capsules was studied by mixing it in commercial cement putty in different ratios (putty/capsules) (70/30) and (80/20). After 2 days drying of the cement putty, the putty panels were kept at 5°C for 60 minutes. Then, they were exposed to heat and the temperature profiles were recorded at regular intervals.

1. Different combination of capsules and standard cement putty

As can be seen from Figure 1, the microcapsules of example 1 when loaded in cement putty showed a lower temperature compared to the standard putty.

2. Temperature Profile of Palm oil capsule

As can be seen from Figure 2, the microcapsules of example 2 when loaded in cement putty showed a lower temperature compared to the standard putty.

3. Temperature Profile of PCM and Palm oil mixed capsules in comparison to as such PCM and Palm oil capsules

As can be seen from Figure 3, the microcapsules of example 1, 2 and 3 when loaded in cement putty showed a lower temperature compared to the standard putty.

4. Temperature Reduction profile of hybrid capsules

The synthesized hybrid capsules of example 4 were mixed with standard cement putty separately in 80:20 ratios and applied on cement fiber panels at 4 mm thickness. The panels were dried for 48 hours and then subjected to a cooling cycle of 1 hour at 5°C. The panels were kept on hot plate maintained at a temperature range of 45-50°C and the increase in temperature is noted with respect to time. A standard panel (without any capsule) was also tested as a control. As is evident from Figure 4, the microcapsules of example 4 when incorporated in cement putty showed a lower temperature compared to the standard putty.

List of figures
Figure 1: Temperature profile vs. time for standard cement putty and microcapsules loaded in cement putty

Figure 2: Temperature profile vs. time for standard cement putty and microcapsules loaded in cement putty

Figure 3: Temperature profile vs. time for standard cement putty and microcapsules loaded in cement putty

Figure 4: Temperature profile vs. time for standard cement putty and microcapsules loaded in cement putty

Figure 5: Standard Primer vs experimental primer with 10% Capsules

Figure 6: Standard Primer vs experimental primer on cement putty (CP)

Compressive Strength Measurements:
The compressive strength of the cement putty was tested on the compressive strength testing machine by making 25 cm2 cubes.

Table 2: Compressive strength data of the cement cubes
Sample Description 7 Days Result
KN MPa
Example 1 Organic capsules with PCM 28 at 20% loading in cement putty 1.36 0.54
Example 2 Organic capsules with palm oil at 20% loading in cement putty 1.08 0.42
Example 4 Hybrid microcapsules with 7.9% TEOS at 20% loading in cement putty 2.94 1.16

Table 2, reveals that the hybrid microcapsules show increased values of compressive strength compared to the organic capsules due to improved compatibility of the microcapsules with cementitious materials.

Example 8
Preparation of Aqueous slurry of Microcapsules

Encapsulation of Phase changing material (PCM 28), having 28 deg C melting points by Epoxy Phenalkamine system
RM F=1(%)
Water 66.904
PVA-124 3.496

Lapox B11 7.2
PCM-28 12.5

Phenalkamine PPA 7041 5.3

Water 4.6
100

Process for encapsulation PCM-28 comprises the steps of

a. Adding DM Water to the reactor and raising the temperature to 80°C;
b. adding Polyvinyl alcohol (PVA-124) and stirring for 1 hour at 300 RPM;
c. cooling to 600C once homogeneous solution is obtained;
d. charging Lapox B11 (Diglycidyl ether of bisphenol A) and PCM-28 one after another under stirring and continue stirring for 30 minutes;
e. charging PPA 7041 to the reactor in 30 minutes duration (PHENALKAMINE EPOXY HARDENER);
f. allowing the reaction to run at 60°C for 1 hour 30 minutes;
g. increasing the temperature to 70°C and maintaining it for 1 hour;
h. increasing the temperature to 80°C and run it for 1 hour;
i. the batch is allowed to cool to 40°C under stirring and discharged as such as a aqueous suspension of microcapsules having a solid content of 28.5%

Study of aqueous suspension of microcapsules in primer coating

10 parts by weight of aqueous slurry of microcapsules (28.5% solids) of experiment 8 is incorporated in a standard primer sample available commercially. The standard primer is a water thinnable primer which is commercially available.
The primer is diluted with 1:1 water and applied on a cement board panel of 6x4 inches. The graphs of the hot plate studies for the panels coated with the standard primer and the primer containing the aqueous slurry of microcapsules can be seen in Figure 5, where the experimental primer showed a lower temperature rise than the standard primer.
In another experiment, the system of cement putty and water based primer was studied. The putty contains 10% microcapsules as a dry powder and the primer contains the 10% aqueous suspension of microcapsules. As seen from Figure 6, the system containing microcapsules showed a lower temperature than the standard system.