Claims:We Claim:

1. High solid silicone resin grafted acrylic copolymers comprising silicone resin grafted acrylic copolymers having hydroxy functional monomers of castor oil and -OH functional acrylic monomers enabling said silicone resin grafted acrylic copolymers of low molecular weight (weight average) in the range of 9000-32000 (mw) and yet with enhanced weathering and anticorrosive performance properties.

2. High solid silicone resin grafted acrylic copolymers as claimed in claim 1 wherein said silicone resin grafted acrylic copolymer comprises castor oil 10-30 %, silicone resin 0.5-10% on resin solids having 3-7% silanol (SiOH) functional groups together with acrylates and optionally styrene as monomers, said copolymers of said low molecular weight (weight average) in the range of 9000-32000 (mw) is provided in combination of polar and non-polar solvent to achieve desired lower Stormer viscosity at 30°C of: 300-800 gm at high solids adapted for 2K polyurethane paint formulation including ambient curing pigmented paint formulations compatible with organic/ inorganic pigments, corrosion inhibiting pigment, extenders, and additives for semi glossy to glossy direct to metal coatings with enhanced weathering and anticorrosive performance properties.

3. High solid silicone resin grafted acrylic copolymers as claimed in claims 1 or 2 wherein said silicone resin grafted acrylic copolymer preferably comprises following ingredients on resin solids:
Castor oil 10-30%;
n-Butyl acrylate 5-45%;
Hydroxyethyl methacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5- 7% selected from silanol / methoxy functional silicones
Optionally, n-butyl methacrylate 5- 15 %, as monomers on resin solids.

4. High solid silicone resin grafted acrylic copolymers as claimed in claims 1-3 wherein said silicone resin grafted acrylic copolymer preferably comprises following ingredients on resin solids:
Castor oil 10-30%;
Styrene 5-25 %;
n-Butylacrylate 5-45%;
Hydroxyethyl methacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5- 7% selected from silanol / methoxy functional silicones
Optionally, n-butyl methacrylate 5- 15 %, as monomers on resin solids.

5. High solid silicone resin grafted acrylic copolymers as claimed in claims 1-4 wherein in said silicone resin grafted acrylic copolymer having grafted silicone resin in lower levels of 0.5-2% on resin solids is obtained of Di-tertiary butyl peroxide based free radical polymerization, and, higher levels of grafted silicone resin of 3-10% is obtained of tert-Butyl peroxybenzoate based free radical polymerization in combination of polar and non-polar solvent preferably hydrocarbon/ oxygenated solvents having boiling point in excess of of 125°C and includes xylene and cyclohexanone based solvent mixture.

6. High solid silicone resin grafted acrylic copolymers as claimed in claims 1-5 that is solvent borne having percent non-volatile matter: 80- 85, hydroxyl value (mg KOH /gm): 60- 100, Acid Value (mg KOH /gm): 5-10, Renewable monomer content on Resin solids: 15-30 percent.

7. High solid silicone resin grafted acrylic copolymers as claimed in claims 1-6 that is curable preferably ambient temperature curable provided as 2K polyurethane paint formulations involving said high solid silicon resin grafted acrylic copolymers having Percent NVM 86-90, Volume solids 78-82 percent, PVC 18-22 percent, Viscosity of base on stormer: 300-800 gm that favours following characteristics post application and curing: Direct to Metal: DFT / coat = 75- 150 micron. Sag resistance: Passes: 200 micron, Drying time: Surface dry: 1.5 -2.5 hr, Handle able: 4-6 hrs. Gloss at 60 degree = 75-85, VOC content during application: < 250 gm /litre, Pot life: 2 -3 hrs. Flexibility 1/8 inch Mandrel: Pass, Crosscut adhesion: 5B, Scratch Hardness: > 2 Kg sheen scratch hardness tester.

8. A process for manufacturing said high solid silicone resin grafted acrylic copolymers as claimed in claims 1-7 comprising the steps of providing
hydroxy functional monomers of castor oil and -OH functional acrylic monomers together with silicone resin and acrylate monomers optionally including styrene in various portions;
free radical polymerizing said monomers in presence of select initiators and select solvent to obtain therefrom said silicone resin grafted acrylic copolymers of low molecular weight (weight average) in the range of 9000-32000 (mw) and yet with enhanced weathering and anticorrosive performance properties.

9. A process for manufacturing said high solid silicone resin grafted acrylic copolymers as claimed in claim 8 comprising adding portion wise said monomers and initiator as reactor charge based on the following steps
Providing Portion I comprising Commercial Castor Oil in combination of polar and non-polar solvent including mixed Xylene and cyclohexanone that is heated to a temperature of 130-145°C;
Adding Portion II comprising styrene, acrylate monomers and initiators, to Portion I at uniform rate over 3.5-4.5 hours of time at 130-145°C;
Adding Portion III comprising mixed xylene to the above reaction mixture and allowing the reaction to continue for 1-2 hours followed by cooling the reaction mixture to 120-130 oC;
Adding Portion IV comprising silicone resin to the above reaction mass and heated to 140-150oC followed by monitoring % NVM and viscosity of the resin to ensure monomer conversion and silicone grafting;
Continuing the reaction until monomer conversion of >99.0% is achieved and obtaining therefrom resulting high solid siliconized acrylic polyol resin as clear solution with NVM 78-90 % by weight of polymer solids, hydroxyl value of 60-100 mg KOH /gm, acid value of 4-10 mg of KOH/g, viscosity of Z1-Z4 on Gardner scale at 25OC and average molecular weight by GPC 9000-32000.

10. A process for manufacturing said high solid silicone resin grafted acrylic copolymers as claimed in claim 8-9 wherein said reactor charge comprises
Castor oil 10-30%;
Styrene 5-25 %;
n-Butylacrylate 5-45%;
Hydroxyethylmethacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5-7% selected from silanol / methoxy functional silicones;
Optionally, n-butyl methacrylate 5-15%, as monomers on resin solids; or,
styrene free reactor charge comprising
Castor oil 10-30%;
n-Butylacrylate 5-45%;
Hydroxyethyl methacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5- 7% selected from silanol / methoxy functional silicones
Optionally, n-butyl methacrylate 5- 15 %, as monomers on resin solids.

11. A process for manufacturing said high solid silicone resin grafted acrylic copolymers as claimed in claims 8-10 wherein for said silicone resin grafting in lower levels of 0.5-2% on resin solids Di-tertiarybutyl peroxide based free radical polymerization is employed, and, for higher levels of said silicone resin grafting of 3-7% on resin solids tert-Butyl peroxybenzoate based free radical polymerization is employed in said xylene and cyclohexanone based solvent mixture

12. A process for the manufacturing of said high solid silicone resin grafted acrylic copolymers as claimed in claims 8-11 adapted for a curable polyurethane paint formulation when cured with aliphatic/ cycloaliphatic polyisocyanates or their blends selected from isocyanate-terminated prepolymer or blocked isocyanates and are selected from hydrogenated methylene diphenyl diisocyanate, isophorone diisocyanate, hexa methylene diisocyanate, biurates & isocyanurate of hexamethylene di-isocyanate and isophoron di-isocyanate at NCO: OH ratio of 1:1 providing improved mechanical, corrosion resistance and weathering performance.

13. A process for the manufacturing of said high solid silicone resin grafted acrylic copolymers as claimed in claims 8-12 wherein said initiators include peroxide, hydroperoxide, or azo compound preferably the initiators with a decomposition temperature greater than about 100° C and selected from tert-butyl hydroperoxide, di-tert-butyl peroxide, Di tertiary amyl peroxide, cumene hydroperoxide, dicumyl peroxide, tert-Butyl peroxy 2-ethylhexyl carbonate, Di tertiary butyl amyl peroxide, para tert-Butyl peroxy benzoate.

Dated this the 24th day of July, 2021 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
IN/PA-199
, Description:FIELD OF INVENTION

The present invention provides for high solid silicone resin grafted acrylic copolymers and a process for the synthesis of said grafted acrylic copolymers having -OH functionalities sourced from renewable and non-renewable monomers as hydroxy functional monomers, preferably castor oil and hydroxyethyl methacrylate as hydroxy functional monomers, to yield said silicone resin grafted acrylic copolymers of low molecular weight and yet having enhanced weathering and anticorrosive performance properties in 2K polyurethane coating compositions.

BACKGROUND ART
Available literature on high solid acrylics or their modifications teaches about high solid acrylic copolymers based on commonly used acrylic monomers as well as high solid acrylics with renewable monomers like Castor Oil. There are also references having high solid acrylic copolymers modified with silicone resin. The two synthetic approaches have distinct difference in performance properties.

EP0275051A2 discloses about a process and resulting composition produced by in-situ copolymerization of ethylenically unsaturated monomers, including acrylic monomers and hydroxylated monomers, in the presence of silicone resin containing hydroxyl groups or lower alkyl groups to produce a stabilized, non- gelled acrylic-silicone copolymer mixture. This prior art further pertains to in-situ copolymerization of 30 acrylic and glycidyl monomers in the presence of such silicone resin to produce a stabilized non-gelled acrylic-silicone copolymer mixture. The in-situ polymerization processes can be in bulk (solvent-free) or in the presence of organic solvent which can be subsequently stripped from the resulting polymer mixture. The polymer can be combined with other components to produce a clear or pigmented binder system for powder coatings.
WO 2010/100121 A1 discloses the synthesis of hydroxy functional oil polyol acrylic graft copolymers. This was accomplished by heating epoxidized vegetable oil and a hydroxy functional material in the presence of an acid catalyst to prepare hydroxyl functional oil poyol and reacting the same with a mixture of ethylenically unsaturated monomer composition in presence of an initiator. The polymers prepared thereof were cured with suitable crosslinker to prepare coating compositions for food & beverage packaging containers.

EP2999726B1 discloses acrylic polyols comprising hydroxy functional acrylic copolymers/resin involving an acrylic backbone having carboxylic acid anhydride modified castor oil as hydroxy functional monomer and with hydroxyl value of the acrylic polyols in the range of 40 to about 90 mg KOH/gm. They claimed high solids of upto 100 percent and renewable content of upto 50 percent having weight average molecular weights within the range of about 10000 to 100000 and having a glass transition temperature (Tg) within the range of about -20 degree C to about 50 degree C.

WO2017208252A1 discloses high solid acrylic polyols comprising hydroxy functional acrylic copolymers/resins are provided having hydroxyl functionality sourced solely or partially through renewable and modified castor oil wherein the copolymers had up to 100 percent solids and high hydroxyl values ranging from 80-200 (mg KOH /gm). Said high solid acrylic polyols involving modified castor oil as monomers favoured complete or partial replacement of soft monomers like butyl acrylate, 2-ethyl hexyl acrylate, lauryl acrylate and the like in said high solid acrylic polyol synthesis. The renewable content of these resins can be as high as 70 percent on resin solids thereby providing economical and sustainable polymer for high performance coatings. The synthesized high solid acrylic polyols find application in high solid and high build coatings having low Volatile Organic Component (VOC) content for decorative and industrial use. Said high solid acrylic polyols have been synthesized by co-reacting acid anhydride modified castor oil as sole/major hydroxyl functional monomer with variety of acrylic monomers, styrene or its derivatives and optionally hydroxyalkyl acrylates / methacrylates and ethylenic monomer through free radical polymerization in presence of initiator(s).

US 2002/0156220A1 discloses acrylic copolymers which have ester linkages which are part of a repeating side groups which extend from the longitudinal polymer chain. The acrylic copolymers of the invention are effective for providing polymeric Vehicles and formulated coating compositions for coating binders that are high in Solids and have reduced levels of volatile organic Solvents or volatile organic compounds. It provides desirable properties, such as gloss retention, low Viscosity, a Tg of about -10 degree C. to about 60 degree C, and in an important aspect, about 30 degree C. to about 5 C., and a hardness of at least about 2B after curing. The lower hydroxyl values of the acrylic copolymers require lower amounts of cross-linker such as isocyanate crosslinkers, yet still permit the modified acrylic polymers of the invention to provide an isocyanate cured coating binder with a pencil hardness of at least about 2B and gloss retention of at least about 50 percent after 1,000 hours of ultra violet light exposure.

CN104311726A discloses a method for preparing acrylic resin for coating and painting ink industry, and particularly to a method for preparing solid acrylic resin. The method comprises the following steps: adding a hard monomer, a soft monomer, a functional monomer, an initiator, a chain transfer agent and an auxiliary component into a reaction kettle to perform a polymerization reaction; when the total conversion rate of the monomers in the reaction kettle is 40-50 percent, gradually dripping a diluted solvent into the reaction kettle to reduce the viscosity until the total conversion rate of the monomers in the reaction kettle is 70-80 percent, and discharging the obtained dilution from the reaction kettle into a storage tank; then continuously pumping the dilution into a tubular reactor from the storage tank to perform polymerization reaction; conveying a reaction product into a devolatilization tower after being discharged from the tubular reactor, discharging solid acrylic resin with the dilution solvent from the lower part of the devolatilization tower to obtain the solid acrylic resin. The method provided by the invention is used for overcoming the defects that bulk polymerization easily generates explosion, and the polymerization temperature is hard to control, and improving the utilization efficiency of the equipment.

CN101724121A discloses a high-solid low viscosity thermoplastic acrylic resin which contains the components in percent by weight: a component A: 0.5-2 percent of acrylic acid, 10-30 percent of methyl methacrylate, 15-35 percent of styrene and 5-15 percent of ethyl acrylate and 1.0-5.4 percent of acrylamide; a component B: 15-35 percent of methylbenzene and 10-25 percent of acetic ether; and a component C: 0.3-1 percent of ditert-buyl peroxide. The preparation method of the acrylic resin comprises the following steps of: a. according to the proportion of the components, firstly throwing the component B to a reaction kettle, and replacing air in the reaction kettle with nitrogen and heating to 100-140 DEG C; b. dropping the component A and the component C to the reaction kettle in the step a and ending dropping within 1-4h, wherein the component C is dropped separately; and c. reacting for 6-10h after the step b is completed, measuring the content of the solids and then filtering and packing after the index value is reached to obtain the thermoplastic acrylic resin.
US6762263B2 discloses processes for the controlled radical polymerization of acrylic and related polymers to produce improved low VOC coating materials, or powder coating compositions, the novel polymers so produced, the catalyst systems employed, processes for application of the improved coatings, coatings so produced and objects coated on at least one surface with the novel coatings are disclosed.

CA2505953C discloses a novel polyol prepolymer including either an aliphatic amine, cycloaliphatic amine, aromatic amine or a mixture of these with an epoxy functional silicone to produce the novel polyol prepolymer chain extender. In one aspect of the invention, the novel polyol prepolymer chain extender is reacted with an epoxy resin to produce a novel silicone modified epoxy resin having improved adhesion, chemical resistance, UV stability, and decreased shrinkage properties. In another aspect of the invention, the novel polyol prepolymer chain extender is reacted with an acrylic monomer to produce a novel silicone modified acrylic resin having improved adhesion, chemical resistance, UV stability, increased functionality, and decreased shrinkage properties. The present invention also provides for a novel solid surface material composition.

US-5476912 discloses an adhesive which exhibits excellent adhesiveness and is capable of firmly adhering an acrylic resin and a silicone rubber together at a temperature of as low as about 20 to 30°C. requiring a time of as short as several minutes. The adhesive is obtained by dissolving in a solvent a novel silicone-modified acrylic copolymer having a poly organosiloxane with an SiH reaction point on the side chain.

Reference is also drawn to JP 2018002971 that teaches thermosetting silicone resin comprises (A) 70-98 parts of condensation reaction type resinous organopolysiloxane (solid at 25°), (B) 2-30 parts of organopolysiloxane having a linear diorganopolysiloxane residue represented by -[Si(R1)(R2)]m- and having at least one cyclohexyl group or Ph group in one mol. (where, R2 = independently a hydroxyl group, a monovalent hydrocarbon group selected from an C1-3 alkyl group, a cyclohexyl group, a Phenyl group, a vinyl group and an allyl group, m = an integer of 5 - 50), (C) 1 - 30 parts of acryl-modified silicone resin powder, (D) 300 - 1,200 parts of inorganic filler and (E) 0.01 - 10 parts of organometallic condensation catalyst, based on 100 parts of the total of components (A) and (B). Thus, 90 parts resinous organopolysiloxane (polysiloxanes, Me, hydroxy-containing, isopropoxy-containing, 10 parts linear organopolysiloxane (chlorodimethylsilyl-terminated polydimethylsiloxane-methylphenyldichlorosilane-phenyltrichlorosilane hydrolytic copolymer (preparation shown), 5 parts acryl-modified silicone resin powder (Chaline R 170S), 600 parts inorganic filler (CS 6103-53C2), 1 parts organometallic condensation catalyst (zinc benzoate), 150 parts titanium dioxide rutile type (PC-3), 2 parts hardened castor oil (Kaowax 85P) and 0.5 parts 3- mercaptopropyltrimethoxysilane (KBM-803) were mixed with hot two-roll mill, cooled and pulverized to obtain a thermosetting silicone resin compounds. This prior art thus teaches a physical blend comprising of 90 parts resinous organopolysiloxane , 10 parts linear organopolysiloxane, 5 parts acryl-modified silicone resin powder, 600 parts inorganic filler (CS 6103-53C2), 1 parts organometallic condensation catalyst (zinc benzoate), 150 parts titanium dioxide rutile type (PC-3), 2 parts hardened castor oil (Kaowax 85P) and 0.5 parts 3- mercaptopropyltrimethoxysilane mixed with hot two-roll mill, cooled and pulverized to obtain a thermosetting silicone resin compounds. Presence of Castor Oil in the composition is an additive and not as reactant and also does not teach any hydroxy functional acrylic copolymer involving castor oil prepared in a solvent medium through free radical polymerization using initiator and the same being grafted with silicone resins.

WO2015005317 teaches about oxidative curing, alkyd-modified silicone acrylic copolymer that is obtained by reacting (a) an oxidative curing acrylic copolymer, and (b) a silicone having at least a hydroxyl group and/or an alkoxy group. The oxidative curing acrylic copolymer (a) is a copolymer obtained through graft polymerization of a monomer indicated by (a-1) styrenes, (a-2) (meth)acrylic acid esters, and (a-3) predetermined polymerizable unsaturated monomers, to an alkyd resin (c) having an oxidative polymerizable group. Thus, phthalic anhydride, dehydrated castor oil fatty acid, glycerin, and pentaerythritol were reacted to give an alkyd resin, which was graft-polymerized with iso-Butyl methacrylate, tert-Butyl methacrylate, Butyl acrylate, styrene, 2-hydroxyethyl methacrylate, and methacrylic acid and then reacted with Z 6018 (Ph Pr silicone) to give an alkyd-modified silicone-acrylic copolymer. A normal-temperature curable coating compound containing the resulting copolymer was applied on a glass plate and dried to give a film showing JIS Z 8741 gloss 85-90°.
This prior art teaches synthesis of an alkyd resin having Dehydrated castor Oil Fatty acid (acid Value 200-205 and OH value < 25 mg KOH /gm), Phthalic anhydride, glycerine and pentaerythritol generally at temp in excess of 220ºC with azeotropic solvent. The resultant alkyd is then copolymerized with acrylic monomers / initators followed by grafting with silicone resin. The resultant silicone modified acrylated alkyd based coating dries through autoxidative curing/ thermoplastic nature of the polymer and does not need any external crosslinker for the curing/ drying of the film, and hence does not teach any acrylic copolymer chemistry with castor Oil as -OH functional renewable monomer (-OH Value 165-175 mg KOH /gm) followed by in situ grafting with silicone resin, which resultant acrylic copolymer with grafted silicone resin needs either polyisocyanate (for ambient temperature curing 2K PU) or amino resins for 1 K stoving system at elevated temperatures.
Synthesis and characterization of novel silicone acrylate–soya alkyd resin as binder for long life exterior coatings, ch 2007 Progress in Organic Coatings 58(4):259-264 DOI: 10.1016/j.porgcoat.2006.11.002 teaches a polymeric binder on soya alkyd, silicone intermediate and 2-hydroxyethyl methacrylate has been synthesized for formulation of long life exterior coating. Initially silicone acrylate monomer (SAM) was prepared by reacting hydroxyl-terminated silicone and 2-hydroxyl ethyl methacrylate (HEMA) and characterized by Fourier transformer infrared spectroscopy (FTIR) and carbon nuclear magnetic resonance spectroscopy (13C NMR). SAM was used in varying concentrations to synthesize novel soya alkyd resin. The unpigmented polymer film obtained from silicone acrylate–soya alkyd resin exhibits excellent mechanical properties and good exterior durability compared to silicone modified alkyd resin.
This prior art teaches about first synthesis of hydroxy functional silicone acrylate monomer (SAM) by reacting hydroxyl-terminated silicone and 2-hydroxyl ethyl methacrylate (HEMA). SAM was then incorporated in varying concentration into soya Oil based alkyd resin. The resultant SAM modified soya alkyd based clear films have been characterized for their mechanical properties and exterior durability vis-à-vis standard silicone modified alkyd resin obtained through silicone resin modification. Hence does not teach any high solid siliconized acrylic copolymer suitable for 2K and 1K systems with polyisocyanate and amino resin crosslinkers respectively for high durable and corrosion resistant low VOC coatings.

However, there is no available knowledge on high solid acrylic copolymers having renewable hydroxy functional monomer i.e. simple castor oil and hydroxyethyl methacrylate as hydroxy functional acrylic monomers with grafted silicone resin into the backbone of said copolymers, and hence there is a need in the art to attain such silicone resin grafted acrylic copolymers having castor oil and hydroxyethyl methacrylate as hydroxy functional monomers that are low in molecular weights and that would not only enhance the performance properties even being low in molecular weights, but such renewable castor oil involvement would also reduce usage of -OH functional acrylic monomer like hydroxy ethyl methacrylate as well as soft monomer like butyl acrylate to achieve desired viscosity and hydroxyl value. Further to that the renewable monomer component would significantly reduce the material cost of such high solid silicone modified acrylic copolymer while ensuring desired performance properties in 2K polyurethane paints whereby such involvement of renewable monomer would reduce overall carbon footprint impact of the acrylic copolymers and consequently paints obtained thereof.

OBJECTS OF THE INVENTION

The primary object of the present invention is to provide for high solid silicone resin grafted acrylic copolymers having -OH functionalities sourced from renewable and non-renewable monomers comprising high solid hydroxy functional acrylic copolymer of castor oil and hydroxyethyl methacrylate as hydroxy functional monomers, and, acrylates, of low molecular weight.

Another object of the present invention is to provide for said high solid silicone resin grafted acrylic copolymers having grafted silicone resin together with renewable monomer that would have enhanced weathering and anticorrosive performance properties even at low molecular weight.

Yet another object of the present invention is to provide for said high solid silicone resin grafted acrylic copolymers that would have relatively lower hydroxyl value wherein said high solid hydroxy functional silicone copolymers would enable high build low VOC paints meant for 2K polyurethane systems with polyisocyanate curing agents.

SUMMARY OF THE INVENTION

According to the basic aspect of the present invention there is provided high solid silicone resin grafted acrylic copolymers comprising silicone resin grafted acrylic copolymers having hydroxy functional monomers of castor oil and -OH functional acrylic monomers enabling said silicone resin grafted acrylic copolymers of low molecular weight (weight average) in the range of 9000-32000 (mw) and yet with enhanced weathering and anticorrosive performance properties.

In said high solid silicone resin grafted acrylic copolymers said silicone resin grafted acrylic copolymer comprises castor oil 10-30 %, silicone resin 0.5-10% on resin solids having 3-7% silanol (SiOH) functional groups together with acrylates and optionally styrene as monomers, said copolymers of said low molecular weight (weight average) in the range of 9000-32000 (mw) is provided in combination of polar and non-polar solvent to achieve desired lower Stormer viscosity at 30°C of: 300-800 gm at high solids adapted for 2K polyurethane paint formulation including ambient curing pigmented paint formulations compatible with organic/ inorganic pigments, corrosion inhibiting pigment, extenders, and additives for semi glossy to glossy direct to metal coatings with enhanced weathering and anticorrosive performance properties.

According to another preferred aspect of the present invention there is provided high solid silicone resin grafted acrylic copolymers wherein said silicone resin grafted acrylic copolymer preferably comprises following ingredients on resin solids:
Castor oil 10-30%;
n-Butyl acrylate 5-45%;
Hydroxyethyl methacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5- 7% selected from silanol / methoxy functional silicones
Optionally, n-butyl methacrylate 5- 15 %, as monomers on resin solids.

Preferably in said high solid silicone resin grafted acrylic copolymers said silicone resin grafted acrylic copolymer preferably comprises following ingredients on resin solids:
Castor oil 10-30%;
Styrene 5-25 %;
n-Butylacrylate 5-45%;
Hydroxyethyl methacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5- 7% selected from silanol / methoxy functional silicones
Optionally, n-butyl methacrylate 5- 15 %, as monomers on resin solids.

According to another preferred aspect of the present invention there is provided high solid silicone resin grafted acrylic copolymers wherein in said silicone resin grafted acrylic copolymer with grafted silicone resin in lower levels of 0.5-2% on resin solids is obtained of Di-tertiary butyl peroxide based free radical polymerization, and, higher levels of grafted silicone resin of 3-10% is obtained of tert-Butyl peroxybenzoate based free radical polymerization in combination of polar and non-polar solvent preferably hydrocarbon/ oxygenated solvents having boiling point in excess of of 125°C and includes xylene and cyclohexanone based solvent mixture.

Preferably said high solid silicone resin grafted acrylic copolymers is solvent borne having percent non-volatile matter: 80- 85, hydroxyl value (mg KOH /gm): 60- 100, Acid Value (mg KOH /gm): 5-10, Renewable monomer content on Resin solids: 15-30 percent.

According to another preferred aspect of the present invention said high solid silicone resin grafted acrylic copolymers is curable preferably ambient temperature curable provided as 2K polyurethane paint formulations involving said high solid silicon resin grafted acrylic copolymers having Percent NVM 86-90, Volume solids 78-82 percent, PVC 18-22 percent, Viscosity of base on stormer: 300-800 gm that favours following characteristics post application and curing: Direct to Metal: DFT / coat = 75- 150 micron. Sag resistance: Passes: 200 micron, Drying time: Surface dry: 1.5 -2.5 hr, Handle able: 4-6 hrs. Gloss at 60 degree = 75-85, VOC content during application: < 250 gm /litre, Pot life: 2 -3 hrs. Flexibility 1/8 inch Mandrel: Pass, Crosscut adhesion: 5B, Scratch Hardness: > 2 Kg sheen scratch hardness tester.

According to another aspect of the present invention there is provided a process for manufacturing said high solid silicone resin grafted acrylic copolymers comprising the steps of providing
hydroxy functional monomers of castor oil and -OH functional acrylic monomers together with silicone resin and acrylate monomers optionally including styrene in various portions;
free radical polymerizing said monomers in presence of select initiators and select solvent to obtain therefrom said silicone resin grafted acrylic copolymers of low molecular weight (weight average) in the range of 9000-32000 (mw) and yet with enhanced weathering and anticorrosive performance properties.

Preferably in said process for manufacturing said high solid silicone resin grafted acrylic copolymers comprising adding portion wise said monomers and initiator as reactor charge based on the following steps
Providing Portion I comprising Commercial Castor Oil in combination of polar and non-polar solvent including mixed Xylene and cyclohexanone that is heated to a temperature of 130-145°C;
Adding Portion II comprising styrene, acrylate monomers and initiators, to Portion I at uniform rate over 3.5-4.5 hours of time at 130-145°C;
Adding Portion III comprising mixed xylene to the above reaction mixture and allowing the reaction to continue for 1-2 hours followed by cooling the reaction mixture to 120-130 oC;
Adding Portion IV comprising silicone resin to the above reaction mass and heated to 140-150oC followed by monitoring % NVM and viscosity of the resin to ensure monomer conversion and silicone grafting;
Continuing the reaction until monomer conversion of >99.0% is achieved and obtaining therefrom resulting high solid siliconized acrylic polyol resin as clear solution with NVM 78-90 % by weight of polymer solids, hydroxyl value of 60-100 mg KOH /gm, acid value of 4-10 mg of KOH/g, viscosity of Z1-Z4 on Gardner scale at 25OC and average molecular weight by GPC 9000-32000.

Preferably in said process for manufacturing said high solid silicone resin grafted acrylic copolymers said reactor charge comprises
Castor oil 10-30%;
Styrene 5-25 %;
n-Butylacrylate 5-45%;
Hydroxyethylmethacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5-7% selected from silanol / methoxy functional silicones;
Optionally, n-butyl methacrylate 5-15%, as monomers on resin solids; or,
styrene free reactor charge comprising
Castor oil 10-30%;
n-Butylacrylate 5-45%;
Hydroxyethyl methacrylate 5-20%;
Methacrylic acid 0.4-0.5%;
Silicone resin 0.5- 7% selected from silanol / methoxy functional silicones
Optionally, n-butyl methacrylate 5- 15 %, as monomers on resin solids.

According to another preferred aspect of the present invention there is provided a process for manufacturing said high solid silicone resin grafted acrylic copolymers wherein for said silicone resin grafting in lower levels of 0.5-2% on resin solids Di-tertiarybutyl peroxide based free radical polymerization is employed, and, for higher levels of said silicone resin grafting of 3-7% on resin solids tert-Butyl peroxybenzoate based free radical polymerization is employed in said xylene and cyclohexanone based solvent mixture

According to yet another preferred aspect of the present invention there is provided a process for the manufacturing of said high solid silicone resin grafted acrylic copolymers adapted for a curable polyurethane paint formulation when cured with aliphatic/ cycloaliphatic polyisocyanates or their blends selected from isocyanate-terminated prepolymer or blocked isocyanates and are selected from hydrogenated methylene diphenyl diisocyanate, isophorone diisocyanate, hexa methylene diisocyanate, biurates & isocyanurate of hexamethylene di-isocyanate and isophoron di-isocyanate at NCO: OH ratio of 1:1 providing improved mechanical, corrosion resistance and weathering performance.

Preferably in said process for the manufacturing of said high solid silicone resin grafted acrylic copolymers said initiators include peroxide, hydroperoxide, or azo compound preferably the initiators with a decomposition temperature greater than about 100° C and selected from tert-butyl hydroperoxide, di-tert-butyl peroxide, Di tertiary amyl peroxide, cumene hydroperoxide, dicumyl peroxide, tert-Butyl peroxy 2-ethylhexyl carbonate, Di tertiary butyl amyl peroxide, para tert-Butyl peroxy benzoate.

Importantly, high solid low VOC coatings offer numerous advantages over conventional coating system as they considerably reduce emission of volatile organic solvent to the environment and provide high build coatings to achieve desired film thickness in single coat eliminating the need to apply multi coat / multi product systems resulting in faster turn around and saving of application time and cost. Designing of such high solid coatings essentially require high solid/ low viscosity resins and consequently their low molecular weight and reduced crosslinking density are detrimental to the coating performance viz mechanical properties and resistance to corrosion, chemical and outdoor weathering.

Present invention is thus about synthesis of high solid siliconized acrylic copolymers meant for high performance 2K polyurethane coatings and addresses the challenges of achieving low viscosity of the resin at high solids necessary for low VOC while ensuring desired performance properties of the high solid coatings obtained thereof.
It is thus surprisingly found by way of the present invention that the challenges in achieving high solids and low viscosity of siliconized acrylic copolymer is profound and enormous that could only be attained based on select monomer types /concentration, renewable castor oil content, initiator type/ content, selection of solvent and process temperatures, which are necessary to achieve desired high solids of siliconized acrylic copolymer preferably 80% in solids. Such high solid siliconized acrylic copolymer when cured with suitable polyisocyanate curing agent provide good drying properties of the cured film at dry film thickness of 75-150 microns in single coat, pot life of minimum 2 hours and excellent mechanical, corrosion resistance and weathering performance.

Therefore it is thus a significant finding of the present invention that without involving any castor oil-based alkyd/ dehydrated castor oil and by involving simple castor oil having -OH value in the range of 165-175 mg KOH /gm and -OH functionality based acrylic monomers including hydroxyethyl methacrylate as hydroxy functional monomers, silicone resin having at least silanol as functional groups could be grafted on acrylates based on select wt.% monomer contents based on select process parameters, solvents and initiator type content employed, to provide for the desired high solids and low viscosity of siliconized acrylic copolymer, which is further adapted for curing with polyisocyanate curing agent to enable said good drying properties of the cured film at dry film thickness of 75-150 microns in single coat, pot life of minimum 2 hours and excellent mechanical, corrosion resistance and weathering performance.
It was found that when dehydrated castor oil based acrylic copolymer was tried the same gelled prematurely even before completion of monomer mix addition due to high unsaturation coupled with conjugated double bonds in dehydrated castor oil (as indicated under Example 2).
Also Example 1 shows that again when both castor oil and hydroxy acrylate are present to provide high solids in the absence of silicone resin preferably in non-polar organic solvent only, the reaction mix remained un-processable giving undesirable high viscosity.
Further to the above the weight % range as selectively scoped based on the experimentations carried out are important and remain workable to achieve desired viscosity, high solids, hydroxyl value and molecular weight together with carrying out the reaction by involving select solvent combination. Certain monomers that have been preferred in the below exemplified experimentations that not only relate to the best method of working the invention but also meets commercial reasons considering the resin cost, and hence should not be construed to limit the scope of the present invention. The silicone resin content range is selective at 0.5-7% being grafted through the reaction with hydroxyl group of acrylic resin. Higher content leads to high viscosity and reduced overall hydroxyl functionality of the final resin that is not desirable as such hydroxyl functionality remains responsible for further reaction with respective polyisocyanates.
Said silicone resin is preferably Dowsil RSN 6018 intermediate & Dowsil 3074 intermediate respectively or similar such resin with silanol / methoxy functionalities.

DETAILED DESCRIPTION OF THE INVENTION

As discussed hereinbefore, the present invention provides for high solid silicone resin grafted acrylic copolymers and a process for the synthesis of the same having -OH functionalities sourced from renewable and non-renewable monomers as hydroxy functional monomers, preferably castor oil and -OH functional acrylic monomers including hydroxyethyl methacrylate, to yield said acrylic copolymers of low molecular weight. Such high solid acrylic has been grafted with silicone resin by reacting part of excess hydroxyls present in acrylic backbone with OH functionality in silicone through etherification.

The high solid silicone resin grafted acrylic copolymers of the present invention achieves multiple objectives in an acrylic copolymer design meant for 2K polyurethane systems a) synthesis of a low molecular weight high solid acrylic with renewable monomer b) Incorporation of silicone resin into such high solid acrylic resin with renewable monomer to enhance weathering and anticorrosive performance properties even at low molecular weight and relatively lower hydroxyl value c) such high solid hydroxy functional silicone modified acrylic copolymers have been employed for high build low VOC 2K polyurethane paints.

In the present invention a more sustainable and cost-effective approach has been employed by incorporating renewable hydroxy functional castor Oil 10-30 % on resin solids together with -OH functionality based acrylic monomers including hydroxyethyl methacrylate for grafting of silicone resin on acrylic polymers to ensure superior gloss, weathering and corrosion resistance performance despite low molecular weight of the designed high solid acrylic copolymer. Use of specifically castor Oil as monomer provides good control on viscosity during grafting with silicone resin in various dosage resulting in high solid siliconized acrylic copolymer at 80-90% NVM. Pure acrylics not having renewable castor oil show significant increase in viscosity, also for the present invention simple castor oil was used as such and not any castor oil based alkyds to attain high solid silicone resin grafted acrylic copolymers. The Commercial castor oil used in the present invention was obtained from M/S Jayant Agro-Organics Limited, Mumbai.
The designed high solid siliconized acrylic copolymer has molecular weight (weight average) of 9000-32000 (mw) with renewable castor oil content of 10-30 % and silicone resin content of 0.5–7.0 % on resin solids. Such Siliconized Acrylic copolymers have been employed in pigmented paint compositions compatible for incorporating organic/ inorganic Pigments, corrosion inhibiting pigment, extenders, and additives to prepare semi glossy to glossy direct to metal coatings.

Designed silicone resin grafted high solid hydroxy functional acrylic copolymers with renewable monomer have been used for designing high build Low VOC polyurethane paints for achieving dry film thickness (DFT) of 75-150 micron in single coat with sag resistance up to 200 micron DFT, dry to handle time of 5-6 hrs despite use of high solid siliconized Acrylic copolymer having low molecular weight and low glass transition temperature. High solid siliconized Acrylic copolymer with renewable monomer obtained from the present invention is capable of achieving volume solids of 80-85 percent thereby allowing the low volatile organic compound (VOC) content of < 250 gm/litre unlike the high VOC content of conventional polyurethane paints with VOC levels of 400-600 gm / Litre.

Typical properties of the High solid siliconized Acrylic copolymer are: Percent non-volatile matter: 80- 85, hydroxyl value (mg KOH /gm): 60- 100, Acid Value (mg KOH /gm): 5-10, Renewable monomer content on Resin solids: 15-30 percent.

Typical properties in ambient temperature curing 2 K polyurethane Paint based on aforesaid High solid siliconized Acrylic copolymer are:

Percent NVM 86-90, Volume solids 78-82 percent, PVC 18-22 percent, Viscosity of base on stormer at 30°C : 300-800 gm

Application Properties: Direct to Metal: DFT / coat = 75- 150 micron. Sag resistance: Passes: 200 micron, Drying time: Surface dry: 1.5 -2.5 hr, Handle able: 4-6 hrs. Gloss at 60 degree = 75-85, VOC content during application: < 250 gm /litre, Pot life: 2 -3 hrs. Flexibility 1/8inch Mandrel: Pass, Crosscut adhesion: 5B, Scratch Hardness : > 2 Kg sheen scratch hardness tester

Following examples provide further information about synthesis of high solid acrylic copolymers and typical characteristics of high solid low VOC paints prepared thereof:

Example 1:
A high solid acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple, and a dropping funnel.

Parts by weight
Portion I
Ortho Xylene 19.0
Commercial Castor Oil 25.0
Portion II
Styrene 34.0
n-Butylacrylate 8.0
n-butyl methacrylate 6.0
Hydroxyethyl methacrylate 5.0
Methacrylic acid 0.5
Ditertiary butyl peroxide
1.5
Portion III
Mixed Xylene 1.0
Total 100

Portion I is charged in the reactor and is heated to the temperature of about 142OC. Portion II is added at uniform rate over 3.5-4.5 hours of time at 138-142OC. After the addition Portion III is added, reaction is allowed to continue for 1-2 hours of time. % NVM and viscosity of the resin are monitored to ensure monomer conversion. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid acrylic polyol resin is clear solution with 78.97.2% by weight of polymer solids, hydroxyl value of 79.3 mg of KOH/g, acid value of 5.23 mg of KOH/g, viscosity of Z5-Z6 on Gardner scale at 25OC.
Inference: Considering to have high solid acrylic polyol in xylene in the absence of polar oxygenated solvent failed leading to undesirable high viscosity.
Example 2:
A high solid acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple, and a dropping funnel.
Parts by weight
Portion I
mixed Xylene 13.0
Cyclohexanone 6.20
Dehydrated Castor Oil 19.0
Portion II
Styrene 10.6
n-Butylacrylate 24.2
Hydroxyethylmethacrylate 18.0
Methacrylic acid 0.4
Tertiary butyl
Perbenzoate 5.0
Portion III (not used)
Mixed Xylene 0.6
Total 100

Portion I is charged in the reactor and is heated to the temperature of 138-140OC. Portion II is added at uniform rate at 138-140OC. After 3 hours of addition of monomer premix (portion II) batch gelled prematurely even before completion of monomer mix addition, and so portion III involving the silicone resin could not be added.
Inference: This may be attributed to high unsaturation coupled with conjugated double bonds present in the dehydrated castor oil.
Example 3:
A high solid acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple, and a dropping funnel.
Parts by weight
Portion I
Ortho Xylene 14.3
Cyclohexanone 5.0
Commercial Castor Oil 21.0
Portion II
Styrene 23.0
n-Butylacrylate 26.0
Hydroxyethylmethacrylate 7.5
Methacrylic acid 0.4
Ditertiarybutylperoxide
2.2
Portion III
Ortho Xylene 0.6
Total 100

Portion I is charged in the reactor and is heated to the temperature of about 142OC. Portion II is added at uniform rate over 3.30-4.30 hours of time at 142OC. After the addition Portion III is added, reaction is allowed to continue for 1-2 hours of time. % NVM and viscosity of the resin are monitored to ensure monomer conversion. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid acrylic polyol resin is clear solution with 79.2% by weight of polymer solids, hydroxyl value of 83.4 mg of KOH/g, acid value of 5.64 mg of KOH/g, viscosity of Z4-Z5 on Gardner scale at 25OC and average molecular weight by Gel permeation Chromatography (GPC) is 15335.
The above resin was tested in direct to metal PU coating of light grey shade cured with Desmodur N 3390 BA/SN (Ex. Covestro) at NCO / OH ratio of 1:1. The mixed paint designed at PVC of 19.4%, and volume solid of 81%. Coating is applied on carbon steel panel using Conventional Air Spray gun after diluting with 10% (v/v) thinner of Xylene / Butyl Acetate mix at dry film thickness of 125 - 150 microns per coat with no sagging tendency upto 220 microns. The coating provided pot life of 80 mins and dry to handle time of 6 hours at 30° C. Initial gloss of the coating was found to be in the range of 84 - 86 at 60° gloss head. Scratch hardness of the film was found to be 2.5 Kg using Sheen Scratch hardness tester after 48 hours, Impact resistance (face) 7 joule using Erichsen impact tester and flexibility of 1/8 inch using Sheen make conical mandrel. Pull of adhesion of the coating checked after 7 days’ air drying on 5mm thick abrasive blast cleaned carbon steel panel and 9 – 10 MPa using PAT model AT-A of make DeFelsko. Abrasion resistance property was checked using TABER Abrader after 7 days curing at ambient temperature and found to be 205 mg weight loss using CS 10 wheel/ 1kg load after 1000 cycles. The panels exposed to QUV 340A as per ASTM G53 with exposure conditions as condensation 45 + 1° C / 4 hours, UV 50 + 1° C / 4 hours at 0.55 + 0. 01 Watts/m2/nm irradiance level, showed 70% gloss retention after 1000 hours. Salt Spray Resistance as per ASTM B 117 checked for the coating at 125-150 micron DFT and observed blisters along scribe and corrosion creepage up to 8 mm from the scribe after 1000 hours exposure with under film corrosion. Coating passed 400 hours humidity resistance without any defect when tested according to ISO 6270.
Inference: In the absence of silicone grafting, inferior weathering and corrosion resistance was found.
Example 4 :
A high solid siliconized acrylic polyol free from Castor oil is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple, and a dropping funnel.
Parts by weight
Portion I
mixed Xylene 13.0
Cyclohexanone 6.0
Portion II
Styrene 12.0
n-Butyl Acrylate 43
Hydroxy ethyl methacrylate 17.0
Methacrylic acid 0.4
Tertiary butyl perbenzoate 5.0
Portion III
Mixed Xylene 0.6
Dowsil RSN-6018 Resin intermediate 3.0
Total 100

Portion I is charged in the reactor and is heated to temperature of about 142OC. Portion II is added at uniform rate over 3.5-4.5 hours of time at 142°C. After the addition completed, Portion III is added, reaction is allowed to continue for 1-2 hours of time. Heating is off and reaction mass is allowed to cool to 130oC. Portion IV is added and reaction mass heated to 150oC. Percent NVM and viscosity of the resin are monitored to ensure monomer conversion and silicone grafting. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid siliconized acrylic polyol resin is clear solution with 79.8% by weight of polymer solids, hydroxyl value of 91 mg KOH/g, acid value of 6.45 mg of KOH/g, viscosity 0f Z5-Z6 on Gardner scale at 25OC.
Inference: Pure acrylic free from Castor Oil with 3% silicone resin grafting provided very high viscosity and therefore could not be tested in paint.
Example 5:
A high solid siliconized acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple and a dropping funnel.
Parts By Weight
Portion I
Mixed Xylene 13.0
Cyclohexanone 6.2
Commercial Castor Oil 16.0
Portion II
Styrene 16.6
n-Butyl acrylate 31.0
Hydroxy ethyl methacrylate 10.7
Methacrylic acid 0.4
tert-Butyl peroxybenzoate 5.0
Portion III
Mixed Xylene 0.6
Portion IV
Dowsil RSN-6018 Resin intermediate 0.5
Total 100

Portion I is charged in the reactor and is heated to temperature of about 142OC. Portion II is added at uniform rate over 3.5-4.5 hours of time at 142OC. After the addition completed, Portion III is added, reaction is allowed to continue for 1-2 hours of time. Heating is off and reaction mass is allowed to cool to 130 oC. Portion IV is added and reaction mass heated to 150oC. % NVM and viscosity of the resin are monitored to ensure monomer conversion and silicone grafting. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid siliconized acrylic polyol resin is clear solution with 79.8% by weight of polymer solids, hydroxyl value of 82 mg of KOH/g, acid value of 5.68 mg of KOH/g, viscosity 0f Z3-Z4 on Gardner scale at 25OC and average molecular weight by GPC is 12640.
The above resin was evaluated in direct to metal PU coating of light grey shade cured with Desmodur N 3390 BA/SN (Ex. Covestro) at NCO / OH ratio of 1:1. The mixed paint has PVC of 19.4%, and volume solids of 80%. Coating is applied on carbon steel panel using Conventional Air Spray gun after diluting with 10% (v/v) thinner of Xylene and Butyl Acetate mix at dry film thickness of 125 - 150 microns with no sagging tendency upto 225 microns. The coating provided pot life of 130 mins and dry to handle time of 6 hours at 30°C. Initial gloss of the coating was found to be 83–86 at 60° gloss head. Scratch hardness of the film was found to be 2.8 Kg using Sheen Scratch hardness tester after 48 hours, Impact resistance (face) 7 joule using Erichsen impact tester and flexibility of 1/8 inch using Sheen make conical mandrel. Pull of adhesion of the coating checked after 7 days’ air drying on 5mm thick abrasive blast cleaned carbon steel panel and 9 – 10 MPa using PAT model AT-A of make DeFelsko. Abrasion resistance property was checked using TABER Abrader after 7 days curing at ambient temperature and found to be 191 mg weight loss while using CS 10 wheel and 1kg load after 1000 cycles. The panels exposed to QUV 340A as per ASTM G53 with exposure conditions as condensation 45 + 1° C / 4 hours, UV 50 + 1° C / 4 hours at 0.55 + 0. 01 Watts/m2/nm irradiance level, showed 77% gloss retention after 1000 hours. Salt Spray Resistance as per ASTM B 117 checked for the coating at 125-150 micron DFT and observed micro blisters along scribe and corrosion creepage up to 7 mm from the scribed line after 1000 hours exposure. Coating passed 450 hours humidity resistance without any defect when tested according to ISO 6270.
Inference: 0.5 % silicone grafting, use of xylene and cyclohexanone allowed lower viscosity required for high solids.
Example 6 :
A high solid siliconized acrylic polyol is prepared by charging following ingredients in to a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple and a dropping funnel.

Parts By Weight
Portion I
Ortho-xylene 14.3
Cyclohexanone 5.0
Commercial Castor Oil 22.0
Portion II
Styrene 21.0
n-Butylacrylate 25.0
Hydroxy ethyl methacrylate 8.0
Methacrylic acid 0.4
Ditertiary butyl peroxide
2.7
Portion III
Ortho-xylene 0.6
Portion IV
Dowsil RSN-6018 Resin intermediate 1.0
Total 100

Portion I is charged in the reactor and is heated to temperature of 138-142OC. Portion II is added at uniform rate over 3.5-4.5 hours of time at 138-142OC. After the addition completed, Portion III is added, reaction is allowed to continue for 1-2 hours of time. Heating is off and reaction mass is allowed to cool to 130oC. Portion IV is added and reaction mass heated to 142oC. Percent NVM and viscosity of the resin are monitored to ensure monomer conversion. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid siliconized acrylic polyol resin is clear solution with 79.77% by weight of polymer solids, hydroxyl value of 85 mg of KOH/g, acid value of 5.79 mg of KOH/g, viscosity of Z3- Z4 on Gardner scale at 25OC and average molecular weight by GPC is 16441.
The above resin was evaluated in direct to metal PU coating of light grey shade cured with Desmodur N 3390 BA/SN (Ex. Covestro) at NCO / OH ratio of 1:1. The mixed paint has PVC of 19.4% and volume solids of 81.5%. Coating is applied on carbon steel panel using Conventional Air Spray gun after diluting with 10% (v/v) thinner of Xylene and Butyl Acetate mix at dry film thickness of 125 - 150 microns with no sagging tendency upto 220 microns. The coating provided pot life of 135 mins and dry to handle time of 6 hours at 30° C. Initial gloss of the coating was found to be in range of 83– 86 at 60° gloss head. Scratch hardness of the film was found to be 3.3 Kg using Sheen Scratch hardness tester after 48 hours, pencil hardness 5H using Sheen pencil hardness tester, Impact resistance (face) 7 joule using Erichsen impact tester and flexibility of 1/8 inch using Sheen make conical mandrel. Pull of adhesion of the coating checked after 7 days’ air drying on 5mm thick abrasive blast cleaned carbon steel panel and 10 – 11 MPa using PAT model AT-A of make DeFelsko. Abrasion resistance property was checked using TABER Abrader after 7 days curing at ambient temperature and found to be 173 mg weight loss while using CS 10 wheel and 1kg load after 1000 cycles. The panels exposed to QUV 340A as per ASTM G53 with exposure conditions as condensation 45 + 1° C / 4 hours, UV 50 + 1° C / 4 hours at 0.55 + 0. 01 Watts/m2/nm irradiance level, showed 85% gloss retention after 1000 hours. Salt Spray Resistance as per ASTM B 117 checked for the coating at 150 micron DFT showed micro blisters along scribe and corrosion creepage up to 5 mm from the scribe after 1000 hours exposure with no under film corrosion. Coating passed 1000 hours humidity resistance without any defect when tested according to ISO 6270.
Inference: Superior performance props of 2K PU paint with DTBP as initiator at lower dosage of silicone grafting.
Example 7 :
A high solid siliconized acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple and a dropping funnel.
Parts By Weight
Portion I
Mixed Xylene 13.0
Cyclohexanone 6.2
Commercial Castor Oil 19.0
Portion II
Styrene 10.6
n-Butylacrylate 29.5
Hydroxyethylmethacrylate 12.7
Methacrylic acid 0.4
tert-Butyl peroxybenzoate 5.0
Portion III
Mixed Xylene 0.6
Portion IV
Dowsil RSN-6018 Resin intermediate 3.0
Total 100

Portion I is charged in the reactor and is heated to temperature of about 145OC. Portion II is added at uniform rate over 3.5-4.5 hours of time at 145OC. After the addition completed, Portion III is added, reaction is allowed to continue for 1-2 hours of time. Heating is off and Portion IV is added at 135oC, again heated to 150oC. % NVM and viscosity of the resin are monitored to ensure monomer conversion and silicone resin grafting. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid siliconized acrylic polyol resin is clear solution with 78.8% by weight of polymer solids, hydroxyl value of 94 mg of KOH/g, acid value is 5.36 mg of KOH/g, viscosity of Z2-Z3 on Gardner scale at 25OC and average molecular weight by GPC is 12547.
The above resin was evaluated in direct to metal PU coating of light grey shade cured with Desmodur N 3390 BA/SN (Ex. Covestro) at NCO / OH ratio of 1:1. The mixed paint has PVC of 19.4% and volume solids of 81.7%. Coating is applied on carbon steel panel using Conventional Air Spray gun after diluting with 10% (v/v) thinner of Xylene and Butyl Acetate mix at dry film thickness of 125 - 150 microns with no sagging tendency upto 220 microns. The coating provided pot life of 135 mins and dry to handle time of 5 hours 30 min at 30°C. Initial gloss of the coating was found to be in range of 83 – 84 at 60° gloss head. Scratch hardness of the film was found to be 2.9 Kg using Sheen Scratch hardness tester after 48 hours, Impact resistance (face) 7 joule using Erichsen impact tester and flexibility of 1/8 inch using Sheen make conical mandrel. Pull of adhesion of the coating checked after 7 days’ air drying on 5mm thick abrasive blast cleaned carbon steel panel and 10 – 11 MPa using PAT model AT-A of make DeFelsko. Abrasion resistance property was checked using TABER Abrader after 7 days curing at ambient temperature and found to be 183 mg weight loss while using CS 10 wheel and 1kg load after 1000 cycles. The panels exposed to QUV 340A as per ASTM G53 with exposure conditions as condensation 45 + 1° C / 4 hours, UV 50 + 1° C / 4 hours at 0.55 + 0. 01 Watts/m2/nm irradiance level, showed 80% gloss retention after 1000 hours. Salt Spray Resistance as per ASTM B 117 checked for the coating at 125-150 micron DFT and found micro blisters along scribe and corrosion creepage up to 6 mm from the scribe after 1000 hours exposure with no under film corrosion. Coating passed 500 hours humidity resistance without any defect when tested according to ISO 6270.
Inference: Change of initiator from DTBP to TBPB, achieved lower viscosity at higher silicone resin content. Marginally inferior props over experiment 6.
Example 8 :
A high solid siliconized acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple, and a dropping funnel.
Parts By Weight
Portion I
Mixed Xylene 13.0
Cyclohexanone 6.2
Commercial Castor Oil 22.0
Portion II
Styrene 6.6
n-Butylacrylate 26.5
Hydroxyethyl
Methacrylate 14.7
Methacrylic acid 0.4
tert-Butyl peroxybenzoate 5.0
Portion III
Mixed Xylene 0.6
Portion IV
Dowsil RSN-6018 Resin intermediate 5.0
Total 100

Portion I is charged in the reactor and is heated to temperature of about 145OC. Portion II is added at uniform rate over 3.30- 4.30 hours of time at 145OC. After the addition completed, Portion III is added, reaction is allowed to continue for 1-2 hours of time. Portion IV is added at 150 OC and % NVM and viscosity of the resin are monitored to ensure monomer conversion and silicone grafting. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid siliconized acrylic polyol resin is clear solution with 78.9% by weight of polymer solids, hydroxyl value of 88 mg of KOH/g, acid value of 5.49 mg of KOH/g, viscosity of Z1-Z2 on Gardner scale at 25OC and average molecular weight by GPC is 10339.
The above resin was evaluated in direct to metal PU coating of light grey shade cured with Desmodur N 3390 BA/SN (Ex. Covestro) at NCO / OH ratio of 1:1. The mixed paint has PVC of 19.4% and volume solids of 80.7%. Coating was applied on carbon steel panel using Conventional Air Spray gun after diluting with 10% (v/v) thinner of Xylene and Butyl Acetate mix at dry film thickness of 125 - 150 microns with no sagging tendency upto 210 microns. The coating provided pot life of 140 mins and dry to handle time of 6 hours at 30° C. Initial gloss of the coating was found to be in range of 78 – 82 at 60° gloss head. Scratch hardness of the film was found to be 2.5 Kg using Sheen Scratch hardness tester after 48 hours, Impact resistance (face) 7 joule using Erichsen impact tester and flexibility of 1/8 inch using Sheen make conical mandrel. Pull of adhesion of the coating checked after 7 days’ air drying on 5mm thick abrasive blast cleaned carbon steel panel and 8 – 9 MPa using PAT model AT-A of make DeFelsko. Abrasion resistance property was checked using TABER Abrader after 7 days curing at ambient temperature and found to be 181 mg weight loss while using CS 10 wheel and 1kg load after 1000 cycles. The panels exposed to QUV 340A as per ASTM G53 with exposure conditions as condensation 45 + 1° C / 4 hours, UV 50 + 1° C / 4 hours at 0.55 + 0. 01 Watts/m2/nm irradiance level, showed 80% gloss retention after 1000 hours. Salt Spray Resistance as per ASTM B 117 checked for the coating at 125-150 micron DFT and observed fine blisters along scribe and corrosion creepage up to 7mm from the scrib after 1000 hours exposure. Coating passed 500 hours humidity resistance without any defect when tested according to ISO 6270.
Inference: Performance similar to above at even lower MW and viscosity with use of TBPB.
Example 9 :
A high solid siliconized acrylic polyol is prepared by charging following ingredients into a reactor flask fitted with water cooled condenser, stirrer, feeding metering pump, thermocouple and a dropping funnel.
Parts By Weight
Portion I
Mixed Xylene 13.0
Methoxy propyl acetate 6.2
Commercial Castor Oil 16.0
Portion II
Methyl methacrylate 16.6
n-Butyl acrylate 31.0
Hydroxy ethyl methacrylate 10.7
Methacrylic acid 0.4
tert-Butylperoxy 2-ethylhexyl carbonate 5.0
Portion III
Mixed Xylene 0.6
Portion IV
Dowsil RSN-6018 Resin intermediate 0.5
Total 100

Portion I is charged in the reactor and is heated to temperature of 138-142OC. Portion II is added at uniform rate over 3.5-4.5 hours of time at 140-142OC. After the addition completed, Portion III is added, reaction is allowed to continue for 1-2 hours of time. Heating is off and reaction mass is allowed to cool to 130 oC. Portion IV is added and reaction mass heated to 150oC. % NVM and viscosity of the resin are monitored to ensure monomer conversion and silicone grafting. The reaction is carried out until monomer conversion is 99.0% or higher. The resulting high solid siliconized acrylic polyol resin is clear solution with 79.57% by weight of polymer solids, hydroxyl value of 83 mg of KOH/g, acid value of 4.70 mg of KOH/g, viscosity 0f Z3-Z4 on Gardner scale at 25OC and average molecular weight by GPC 12983.
Inference: Reaction was carried out in hydrocarbon / oxygenated solvents preferably for this example was carried out in xylene and methoxy propyl acetate with boiling point >125°C with a different initiator i.e. tert-Butylperoxy 2-ethylhexyl carbonate and desired acrylic polyol with viscosity, solids and molecular weight similar to Example 5 could be achieved. In this example, styrene as monomer could be replaced with methyl methacrylate, and hence styrene is not an essential monomer but is preferably included in the above examples to achieve economy of the recipe.
It is thus possible by way of the present advancement to provide for high solid siliconized acrylic copolymers meant for high performance 2K polyurethane coatings by addressing the challenges of achieving low viscosity of the resin at high solids necessary for low VOC while ensuring desired performance properties of the high solid coatings obtained thereof. The challenges in achieving high solids and low viscosity of siliconized acrylic copolymer was enormous that could only be attained based on select monomer types /concentration, renewable castor oil content to reach to the desired product further enabled by a select process involving initiator type/ content, selection of solvent and process temperatures, which are necessary to achieve desired high solids of siliconized acrylic copolymer preferably 80% in solids. Such high solid siliconized acrylic copolymer when cured with suitable polyisocyanate curing agent provide good drying properties of the cured film at dry film thickness of 75-150 microns in single coat, pot life of minimum 2 hours and excellent mechanical, corrosion resistance and weathering performance.