CLIAMS:Claims
I claim
1. A silver-silicone-silica composites composition comprising of:
a) at least one aqueous based silver suspension of about 0.001 to 10 by weight percentage;
b) fumed silica of about 1 to 20 by weight percentage ;
c) silicone oil of about 50 to 90 by weight percentage ;
d) precipitated silica of about 5 to 50 by weight percentage;
wherein the solvent based silver particulate suspension is mixed with fumed silica along with the silicone oil.
2. The composition as claimed in claim 1, wherein aqueous based silver suspension is triangular or spherical shaped nanoparticles of concentration ranging from 11 ppm to 10000 ppm.
3. The composition as claimed in claim 2, wherein silver nanoparticles is in the form of metallic particulates with particle size ranging from 1-20 nanometers.
4. The composition as claimed in claim 1, wherein the fumed silica is selected from a group consisting of hydrophobic silica, hydrophilic silica and mixtures thereof, preferably hydrophilic silica.
5. The composition as claimed in claim 4, wherein the sizes of the particles of the fumed silica range from 100 -200 nanometer.
6. The composition as claimed in claim 1, wherein the fumed silica is untreated and surface treated with polydimethylsiloxane.
7. The composition as claimed in claim 1, wherein the silicone oil is selected from a group consisting of dimethicone, dimethylpolysiloxane, dimethyl siloxane phenyl dimethicone, phenyl trimethicone, flurosilicone and aminosilicone; preferably dimethylpolysiloxane.
8. The composition as claimed in claim 1, wherein the polydimethylsiloxane has an average viscosity of about 350 to about 150000 CST at 25°C and has an average molecular weight of about 49300 to about 423000.
9. The composition as claimed in claim 1, wherein the sizes of the particles of the precipitated silica range from 5-20 micrometer.
10. A process for manufacturing a silver-silicone-silica composites, the process comprising the steps of:
(a) mixing an aqueous or solvent based nano silver particulate suspension of about 0.001 by weight percentage to 10 by weight percentage with about 1 by weight percentage to 20 by weight percentage of the fumed silica in high shear homogenizer at 600-700 rpm at room temperature to form the dispersion of the silver-silica composites suspension;
(b) adding about 50 by weight percentage to 90 by weight percentage of silicone oil slowly to the mixture and mixing at higher speed at room temperature;
(c) boiling the said mixture at about 90 °C to 100 °C for a period of about 1-2 hours;
(d) adding required amount of precipitated silica into the clean ribbon blender or high shear mixer;
(e) slowly adding silver-silica-silicone composites to the mixture;
(f) continuing mixing for about 1 hour or mix till the oil phase turns into fine powder.
11. The process as claimed in claim 10 wherein the process further comprises the step of thermo migration of silver-silica composites from aqueous phase to silicone oil phase.
12. The process as claimed in claim 10 and 11, wherein said silver-silica composites is embeded into silicone oil.
13. The process as claimed in claim 10, wherein said precipitated silica has fine and coarse grades in the weight range of 5 percent to 50 percent.
14. The process as claimed in claim 10, wherein the composites is in powder form and has excellent antimicrobial efficacy on surface of plastics.
15. The process as claimed in claim 10, wherein the composites is being used as master batch for plastics and textile industry.
16. The process as claimed in claim 10, wherein the composites has improved physical and mechanical properties and are easy to disperse in many polymer matrix .
17. The process as claimed in Claim 10, wherein composites has blooming property.
18. The process as claimed in Claim 10, wherein composites helps maintaining hygiene levels in plastic surfaces continuously by utilizing the entire silver quantity loaded into the plastic.
,TagSPECI:[001] Description of the invention
[002] The following specification particularly describes the invention and the manner in which it is to be performed.
[003] Technical field of the invention
[004] The present invention provides a composition and process of preparation of silver-silica-silicone composites with excellent antimicrobial and enhanced physical properties.
[005] Background of the invention
[006] Plastics are prone to attack microbes due to moisture and additives such as plasticizer, surfactant, oils etc. Because of the microbial growth, the physical appearance and aesthetics of the plastics is depleted, causing degradation, discoloration, staining, biofilm and malodour. Many antimicrobial products are commercially available with compositions such as 10'-oxybisphenox arsine (OBPA), 2-n-octyl-4-isothiazolin-3-one (OIT), dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), Tri-butyl tin (TBT), zinc omadine, n-butyl-1,2-benzisothiazolin (BBIT), 3-iodo-2-propynyl butyl carbamate (IPBC) and 2,4,4'-trichloro-2'-hydroxy-diphenyl-ether (TCPP or triclosan).
[007] However, all these conventional antimicrobials have limitations and adverse effect on the environment. Many countries have banned these chemicals especially for food contact and packaging application. Currently these chemicals are replaced by more environmental friendly chemicals and are used primarily for antibacterial surface effects including inorganic silver based antimicrobials. Many silver based products are commercially available but most of them contain silver ion, silver-zeolite or silver-silica.
[008] Typically to achieve good antibacterial property on plastic, a very high level of silver concentration is being used and also majority of silver stays in the polymer matrix remains unused in most of the conventional composites based on minerals such as zeolites, clay etc. However, silver-silicone-silica composite helps to supply silver ions continuously from bulk of plastic materials to the surface of plastics by silicone blooming process and helps maintain hygiene levels in plastic surfaces continuously and utilizes the entire silver quantity loaded into the polymer. Alternatively, the inventive silver-silicone-silica composite is required in very low dosages compared to conventional mineral composites.
[009] KR702163B1 discloses a nano-silver sealant composition comprising petroleum hydrocarbon as diluents. The nanosilver sealant composition comprises 8 to 40 by weight percentage of polydimethylsiloxane, 4 to 25 by weight percentage of a crosslinking agent, 15 to 75 by weight percentage of filler, 11.99999 to 20 by weight percentage of petroleum hydrocarbon, 1 to 2 by weight percentage of aminosilane and 0.00001 to 0.1 by weight percentage of silver nanoparticles. Further disclosed is a nanosilver sealant using the composition and a method for preparing the nanosilver sealant. Since the nanosilver sealant shows an increased degree of dispersion of the silver nanoparticles when compared to conventional nanosilver sealants, it exhibits superior antibacterial and antifungal activity, thereby effectively preventing contamination caused by various kinds of microbes while maintaining joints in a clean state for a longer period of time. The composition comprising nanosilver, polydimethylsiloxane, petroleum hydrocarbon, crosslinking agent i.e. silane and filler i.e. silica is used however the document discusses more about crosslinking agent or binding agent for phase transfer process.
[0010] KR1004027B1 entitled ‘Antibacterial film for food packing from’ discloses an antibacterial food packaging film, is provided to ensure excellent antibacterial property by adding silica nanotubes to which silver nanoparticles into synthetic resin solution. An antibacterial food packaging film containing nanosilver particle containing silica carrier comprises synthetic resin 98 to 99 by weight percentage and nanosilver particle containing silica carrier 1 to 2 by weight percentage. The nanosilver particle containing silica carrier is a nanosilver particle containing silica nanotube. The synthetic resin is at least one selected from a polyethylene resin, polypropylene resin, polystyrene resin, polyester resin, vinyl chloride resin, polyvinylidene chloride resin, polyethylene terephthalate resin, and phenol resin. The composition is nanosilver particle, silica nanotube and LDPE polymer for antimicrobial property however the document does not disclose silver-silica-silicone composite which include integrated silicone polymer in composite.
[0011] JP2011021014A entitled ‘Composition having persistent antibacterial property, and antibacterial film and antibacterial spray, obtained by using the same’ discloses a composition having persistent antibacterial properties, and an antibacterial film and antibacterial spray, obtained by using the same. The composition having persistent antibacterial properties includes one or more polymer or oligomer, and a plurality of nanowires dispersed in the polymer or oligomer. The nanowire has an aspect ratio of greater then 20, forming a network structure. The composition is used, for example, for the antibacterial film, antibacterial spray, etc. The composition comprising nanowires distributed in the polymer or oligomer, wherein the nanowires comprise a core shell structure with silica, silver, polyacrylonitrile. During the process, polyhydroxy compound is used as functionalizing i.e. catalyst agent. The present invention of silver-silica-silicone composite process does not involve any binding agent for phase transfer process.
[0012] CN101999408A entitled ‘Long-acting antimicrobial nano-line composition and antimicrobial thin film and spray formed from the same’ discloses the claims a long-acting antimicrobial nano line composition, comprising at least one polymer or oligomer; and multiple nano lines arranged in the polymer or oligomer, wherein the length to diameter ratio of the nano lines is greater than 20, and the nano lines form a net-like structure, the invention also claims an antimicrobial thin film and a spray formed from the same. The composition comprises the polymer such as PVA, PVP, PEG and the silicon dioxide for antimicrobial property and during the process the Polyhydroxy compound is used as functionalizing i.e. catalyst agent. The present invention does not involve any binding agent for phase transfer process.
[0013] WO2012128406A1 entitled ‘Polyester master batch comprising silver-silica nanocomposites and production method therefore discloses polyester master batch having outstanding antimicrobial properties and to a production method thereof, and more specifically relates to a method involving the production of a silver-silica nanocomposites and the production of a polyester master batch comprising same. This document relates to a production method for a polyester master batch for bedding which has a permanent antimicrobial and deodorizing performance and more particularly can be used in an appropriate ultrafine polyester warp knit pile fabric.
[0014] US8246933B2 entitled ‘Aerosol method for nano silver-silica composites anti-microbial agent’ discloses a method of forming and resulting nano structured composites and includes atomizing a mixture of an amount of each of aminopropyltriethoxysilane, AgNO3, DI water, and ethanol in a carrier gas heating the atomized droplets at a selected temperature for a time sufficient to reduce the Ag to its elemental form in a silica matrix and outputting the nano structured composites particles. A predetermined heating time is from about 0.01 to about 40 seconds and a selected heating temperature is from about 200 to about 800° C. The nano structured composites includes a plurality of nano particles at a contact surface of the composites, dispersed throughout and at a contact surface of the composites or dispersed throughout the composites.
[0015] US20110117152A1entitled ‘Silicone rubber exhibiting effective antimicrobial activity from’ discloses a silicone rubber exhibiting antimicrobial efficacy contains (a) at least one silicone rubber derived from a curable silicone rubber forming composition (b) at least one silver-containing antimicrobial agent incorporated in silicone rubber (a) in X weight percent amount and, c) at least one carboxylic acid incorporated in silicone rubber (a) in Y weight percent amount, silver-containing antimicrobial agent (b) when incorporated by itself in silicone rubber (a) in an amount of X+Y weight percent therein and carboxylic acid (c) when incorporated by itself in silicone rubber (a) in an amount of X+Y weight percent therein imparting no significant antimicrobial activity to silicone rubber (a) but in the combination therein of up to X weight percent silver-containing antimicrobial agent (b) and up to Y weight percent carboxylic acid (c) imparting significant antimicrobial activity to silicone rubber (a) such activity being exhibited at the interface of an exposed surface of silicone rubber (a) and a microbe-populated aqueous material in contact therewith.
[0016] Hence what is needed is an antimicrobial silver-silica-silicone composite for plastic and polymer application.
[0017] Summary of the invention
[0018] The present invention provides an antimicrobial composition of the silver-silica-silicone composites for plastic and polymer applications and process for the preparation thereof. The composites composition comprising of at least one aqueous based silver suspension of about 0.001 to 10 by weight percentage, fumed silica of about 1 to 20 by weight percentage, silicone oil of about 50 to 90 by weight percentage, precipitated silica of about 5 to 50 by weight percentage in which the solvent based silver particulate suspension is mixed with fumed silica along with the silicone oil and any of its modified form.
[0019] A process for manufacturing a silver-silicone-silica composites comprising the steps of mixing the aqueous or solvent based nano silver particulate suspension of about 0.001 by weight percentage to 10 by weight percentage with about 1 by weight percentage to 20 by weight percentage of the fumed silica in high shear homogenizer at 600-700 rpm at room temperature to form the dispersion of the silver-silica composites suspension. Adding about 50 by weight percentage to 90 by weight percentage of silicone oil slowly into first step and mixing at higher speed at room temperature, boiling the said mixture at about 90 °C to 100 °C for a period of about 1-2 hours, adding required amount of precipitated silica into the clean ribbon blender or high shear mixer, slowly adding silver-silica-silicone composites and finally continuing mixing for about 1 hour or mix till the oil phase turn into fine powder.
[0020] The silver-silicone-silica composite obtained by the present invention is used in antibacterial finish for control of growth of microbes on variety of polymer materials, textile fibers, plastics molding, food packaging, medical applications, consumer products, food processing, food packing applications, and construction applications.
[0021] Brief description of the drawings
[0022] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawing. In a drawing, like reference numerals refer to like elements.
[0023] Figure 1(a) illustrates characteristic UV peak data of aqueous silver suspension of spherical particle.
[0024] Figure 1(b) illustrates characteristic UV peak of Silver-silica-Silicone composite of oil form of spherical silver particle.
[0025] Figure 1(c) illustrates characteristic UV peak of Silver–silica-silicone composite in powder form of spherical silver particle.
[0026] Figure 1(d) illustrates characteristic UV peak of aqueous silver suspension of triangular particle.
[0027] Figure 1(e) illustrates characteristic UV peak of plastic i.e. LDPE treated with silver-silica-silicone composite of triangular silver particle.
[0028] Figure 1(f) illustrates characteristic UV peak of plastic i.e. HIPS treated with silver-silica-silicone composite of spherical silver particle.
[0029] Figure 2(a) illustrates the TEM image of spherical silver particle.
[0030] Figure 2(b) illustrates the TEM image of triangular shape silver particle.
[0031] Figure 3(a) illustrates the morphology study with SEM.
[0032] Figure 3(b) illustrates the EDAX analysis to confirm the presence of silver and silica.
[0033] Figure 4(a) illustrates the particle size distribution of silver-silica-silicone composite of spherical silver particle.
[0034] Figure 4(b) illustrates the particle size distribution of silver-silica-silicone composite of triangular silver particle.
[0035] Figure 5 shows a table depicting the antibacterial test results of plastic treated with silver-silica-silicone composite as per JIS Z 2810.
[0036] Figure 6 shows a table depicting the antifungal test results of plastic treated with silver-silica-silicone composite as per ASTM G21.
[0037] Figure 7 shows a table depicting the antibacterial test results of plastic treated with silver-silica-silicone composite as per AATCC 147.
[0038] Figure 8 shows a table depicting the plastic treated with Silver-silica-silicone composite is tested as per EU10/2011 & USFDA 176.170 standard for food contact suitability and found no migration of silver from plastic
[0039] Detailed description of the invention
[0040] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0041] The present invention relates to silver-silica-silicone composites comprising at least one aqueous based silver suspension of about 0.001 to 10 percentage by weight, fumed silica of about 1 to 20 by weight percentage, silicone oil of about 50 to 90 by weight percentage, precipitated silica of about 5 to 50 by weight percentage in which the solvent based silver particulate suspension is mixed with fumed silica along with the silicone oil and any of its modified form.
[0042] Various silver suspensions can be used for the purpose of present invention, considered suitable by a person skilled in the art. The aqueous based silver suspension may be ionic, triangular or spherical composite shaped particle of concentration ranging from 11 ppm to 10000 ppm product i.e. 0.001 to 10% by weight.
[0043] A number of silica may be used for the purpose of present invention, considered suitable by a person skilled in the art. The silica may be unfunctionalised or functionalized with 1 to 20% by weight in the final product.
[0044] Various silicone oils may be used for the purpose of present invention considered suitable by a person skilled in the art. The most preferred silicone oil is poly dimethyl siloxane of viscosity 350-150000 CST, 50 to 90% by weight in final product.
[0045] Various precipitated silica may be used for the purpose of present invention, considered suitable by a person skilled in the art. The precipitated silica is 5 to 50% by weight in the final product.
[0046] Figure 1(a), 1(b) and 1(c) provide spectroscopic measurement of the spherical shaped silver that gives a characteristic UV spectrum which clearly reflects their anisotropic shape. The UV peak is in the range of 380 to 450 nm that is characteristic of the spherical shape yellow silver reported in the invention.
[0047] Figure 1(d), 1(e) and 1(f) provides spectroscopic measurement of the triangular shaped silver that gives a characteristic UV spectrum which clearly reflects their anisotropic shape. The UV peak is in the range of 500 to 750 nm that is characteristic of the triangular shape blue colored silver reported in the invention.
[0048] Figure 2(a) and 2 (b) shows the morphological study of the silver particle by TEM analysis that clearly indicates presence of spherical and triangular shaped silver particle.
[0049] Figure 3 (a) show the morphology structure of SEM analysis that shows that the particle size varies from 1 micron to 30 microns.
[0050] Figure 3 (b) shows the EDAX analysis for determining the presence of silver and silica in silver-silica-silicone composite.
[0051] Figure 4 (a) shows the particle size analysis of silver-silica-silicone composite of spherical silver particle that discloses particles from 1 micron to 100 micron with the average particle size of 16.6 micron.
[0052] Figure 4 (b) shows the particle size analysis of silver-silica-silicone composite in which spherical silver particle discloses particles ranging from 1 micron to 100 micron with average particle size of 31.78 micron.
[0053] Figure 5 shows a table depicting the antibacterial performance of the silver-silica-silicone composite powder treated with plastic surface as per the standard JIS Z 2801 testing and pass the standard.
[0054] Figure 6 shows a table that depicts the antifungal performance of the silver-silica-silicone composite treated with plastic surface as per the standard ASTM G21 testing and pass the standard.
[0055] Figure 7 shows the antibacterial performance of silver-silica-silicone composite treated with plastic surface and tested as per the standard AATCC 147 testing and observed good antibacterial efficacy without zone of inhibition which means non leaching product.

[0056] Figure 8 shows a table that depicts the plastics treated with silver-silica-silicone composite is subjected to migration testing as per the EU 10\2011 and USFDA 176.170 for various stimulants like acetic acid, ethanol, n-heptane and distilled water and found no silver migration form plastic to stimulants.
[0057] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for control of growth of microbes and malodors for variety of polymer materials such as LDPE, PP, HDPE, Nylon, general purpose polystyrene, silicones, PVC, PVA thermoplastic elastomers, acetals, high impact polystyrene, TPO, engineered thermoplastics, poly urethanes, wood plastic composites i.e. WPC in bulk and pellet forms to name some but not limited to it.
[0058] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for control of growth of microbes and can be incorporated in variety of textile fibers such as polyesters, acrylics, nylon, polypropylene, spandex to name some but not limited to it.
[0059] The silver-silicone-silica composite obtained by the process of present invention can be applied during various polymer processes such as plastics molding process, products made out of plastics, extrusions process like water pipes, sanitary pipes and fitting, cable containment strips, products made out of plastics, sheeting process type like PVC vinyl floor, polyethylene bags covers, book laminations, smart cards, credit cards, debit cards and others, products made out of plastics spinning process such as ropes, wires, yarns such as fishnet, fibers such as fiberfill, plastics fibers manufacturing process such as PP fiber, polyester fiber, nylon fiber, acrylic, spandex to name some but not limited to it.
[0060] The silver-silicone-silica composite obtained by the process of present invention can be combined along with other polymer additives such as flow additives, fillers, specialty additives including UV protection additives, lubricants, cross linking agents, antistatic agents, nucleating agents, soil release agents, optical brightening agents, antioxidants, UV stabilizers, curing accelerators, encapsulated fragrances to name some but not limited to it. All of such additional materials are well known to those skilled in the art and are commercially available.
[0061] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for control of growth of microbes on food packaging such as, tetra packs, cutting board, plastic carry bags, drinking water bottles, water cabinets, food containers, foils, food cling wrap, tea pots, storage containers and plastic storage bags, inner surface of domestic refrigerators and house hold goods, baby milk bottle, garbage bags to name some but not limited to it.
[0062] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for controlling growth of microbes on medical applications such as medical devices, plastic tubings and containers, pharmaceutical packing materials, sutures, catheters to name a few but not limited to it.
[0063] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for control of growth of microbes and to avoid formation of stains and odour on consumer applications such as toothbrush and razor blade handles, food processing, food packing applications to name a few but not limited to it.
[0064] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for control of growth of microbes to avoid formation of stains and odour on industrial applications such as kitchen surfaces, work surfaces, chopping boards, and disposable packaging and dishes, plastic automotive components such as dashboards, steering wheels, recycled plastic materials to name some but not limited to it. The composites are easy to disperse in many polymer matrix than conventional silver composites based on zeolites, clay and so on. Silicone improves dispersion properties of the composite and increase uniform spreading of the composite. In addition, silicones have low surface tension and therefore the composite flow properties during molding and extrusion is improved. Dispersion times are faster while the master batch is made and it does not require multiple level mixing during master batching. The inventive composite solves the dispersion challenges of many of the conventional silver composites. The composite has blooming property as it has a silicone moiety which continuously blooms to the surface of the plastic.
[0065] The silver-silicone-silica composite obtained by the process of present invention can be combined with any of the following antimicrobials to provide synergistic effect; 10'-oxybisphenox arsine (OBPA), followed by 2-n-octyl-4-isothiazolin-3-one (OIT) and dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT). Tri-butyl tin (TBT). Other organic antimicrobials generally used for material preservation include zinc omadine, n-butyl-1, 2-benzisothiazolin (BBIT) and 3-iodo-2-propynyl butyl carbamate (IPBC). Antimicrobials used primarily for antibacterial surface effects include the organic 2,4,4'-trichloro-2'-hydroxy-diphenyl-ether (TCPP or triclosan) and the inorganic silver-based antimicrobials to name some but not limited to it.
[0066] In order to fully describe the invention, the following formulation and method examples are set forth. These examples are for the purpose of illustration only and are not to be construed as limiting the scope of the invention in any way.
[0067] Example 1: Silver-silica-silicone composite of spherical silver particles
Aqueous based i.e. 0.001 to 10% by weight in final product spherical particle suspension of silver is mixed with fumed silica which is 1-20% by weight final product and mixed at higher rpm. After this silicone oil is added to the mixture and temperature is raised to 120°C. Mixing is continued until the complete evaporation of solvent and phase transfer from aqueous silver–silica to silicone oil under thermo migration takes place. Finally precipitated silica is added and mixed to get uniform fine powder of silver-silica-silicone oil composite with spherical particle of silver.
[0068] Example 2: Silver-silica-silicone composite of triangular and hexagonal silver particles
Aqueous based i.e. 0.001 to 10% by weight in final product triangular particle suspension of silver is mixed with fumed silica which is 1-20% by weight final product, mixed at higher rpm and silicone oil is added. Temperature is raised to 120°C and mixing is continued until the complete evaporation of solvent and phase transferred from aqueous silver–silica to silicone oil under thermo migration takes place. Finally precipitated silica is added and mixed to get uniform fine powder of silver-silica-silicone composite with triangular particle of silver.

[0069] Example 3: silver-silica-silicone composite of micellar ionic silver
Aqueous based i.e. 0.001 to 10% by weight in final product silver ions is bounded with silicon dioxide and copolymer of PVP or vinyl pyrollidone and vinyl imidazole suspension, then it is mixed with fumed silica which is 1-20% by weight final product, everything is mixed at higher rpm. Then silicone oil is added, temperature is raised to 120°C and mixing is continued until the complete evaporation of solvent and phase transfer of aqueous silver-silica to silicone oil under thermo migration. Finally precipitated silica is added and mixed to get uniform fine powder of silver-silica-silicone composite.

[0070] Example 4: Preparation of Silver-Silica-Silicone composite in high viscous semi solid oil form
Fumed silica which is 1-20% by weight final product is mixed with silicone oil at higher rpm and temperature is raised to 120-150°C. Mixing is continued tunill the complete dispersion of silica into silicone oil takes place. The obtained mixture is cooled to 80°C and aqueous silver suspension i.e. 0.001 to 10% by weight in final product is added, at the same time temperature is maintained at 100-120° until the complete evaporation of solvent and phase transfer from aqueous silver–silica to silicone oil under thermo migration. The final silver-silica-silicone composite is in high viscous semi solid oil form.
[0071] Example 5: Preparation of Silver-Silica-silicone composite powder
Fumed silica which is 1-20% by weight final product is mixed with silicone oil at the higher rpm and the temperature is raised to 120 - 150°C. Continue mixing till the complete dispersion of silica into silicone oil. Cool the mixture to 80°C and add aqueous silver suspension which is 0.001 to 10% by weight in final product. Maintain the temperature at 100-120° until the complete evaporation of solvent and phase transfer of silver–silica to silicone oil under thermo migration. Finally add precipitated silica and mix to get uniform silver-silica-silicone composite powder.
[0072] The silver-silicone-silica composite obtained by the process of present invention is used in antibacterial finish for control of growth of microbes on construction application such as panel boards, polymer wall and ceiling materials and boards, plastic casing for electrical applications, white roofing material or shower curtains, wood-plastic composites, indoor and outdoor applications, tennis nets, flooring and wall vinyl and PVC and PU applications, as pool liners, sheet vinyl flooring and truck tarpaulins, toilet seats cover to name some but not limited to it.
[0073] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.