Form - 3A
THE PATENT ACT, 1970
COMPLETE SPECIFICATION
SECTION 10 "Utilization of nano extenders For part replacement of enhancement of hiding surface coatings"

Ti02 Power

for of

Name of the Applicant: a) Registrar,
b) North Maharashtra University, Jalgaon
P.B.No. 80
Jalgaon 425001 M.S. India
c) Indian
Name of the INVENTORS:-


i) a) Mr. Ravindra Dattatrya Kulkarni
b) Sr. Lecturer,
University Department of Chemical Technology
North Maharashtra University,
Post Box No. 80, Jalgaon-425001 (MS)
India
c) Indian
ii) a) Mr. Shirish Hari Sonawane
b) CSIR-SRF,
University Department of Chemical Technology
North Maharashtra University,
Post Box No. 80, Jalgaon-425001 (MS)
India
c) Indian
iii) a) Dr. Satyendra Mishra.
b)Professor and Head
University Department of Chemical Technology
North Maharashtra University,
Post Box No. 80, Jalgaon-425001 (MS)
India c) Indian

Objectives
a) Optimization of nano particles with reference to following points
1) Type of matrices
2) Order of addition
3) Matrix-salt ratio
4) Salt concentration
5) Temperature

b) Preparation of diverse decorative formulations at different nano particle concentrations and sizes.
c) Establishment of optimum nano particle replacement with reference to hiding power.
d) Development of economical, eco friendly, high opacity coating formulations based on above results.
INTRODUCTION
The formulations of coatings (Paints) throws challenge to chemist for meeting versatile mechanical, optical, rheological, durability etc. requirement at affordable cost. Hiding power measures the ability of coating to hide the defects of a given surface per unit quantity of paint. It is governed by the particle size, particle size distribution, degree of dispersion and refractive index difference between pigment and binder. The hiding power is maximum for optimum particle size, narrow particle size distribution and for maximum R.I. difference between pigment and binder. The most useful tool in formulation for reduction of cost is utilization of extenders. Smaller size extenders with particle dia. less than 1 μm are commonly known as "spacing extenders " or" Ti02 spacers", referring to their presumed ability to separate titanium dioxide particles in dry paint film. Essentially, however, their function is to replace titanium dioxide partially without significantly affecting gloss or brightness. It is also known that with decreasing the particle size, the diluents efficiency increases (effective PVC).

Previous Attempts (Alternative to dry hiding)
Various techniques were developed in the past for alternative to T\02 hiding. These techniques include pittment, spindrift, opaque polymer etc. however, they are characterized by presence of multiple phases, complicated routes and involvement of expensive ingredients. Most of these approaches, as discussed below, require polymer in latex form or paint as water thinnable coatings, restricting their applications. Our approach based on nano particles is entirely governed by current developments in nanotechnology, utilizing cheaper inorganic raw materials and conventional routes for manufacturing of paints.
Pittment method:
Pittment is the trademark of PPG Industries applied to their patented process for the incorporation of closed cells micro voids into coatings. Three possible routes were considered 1) leaching 2) Incorporation of droplets of non solvents 3) Formulations of a gel structure containing dispersed non solvents. The condition to maintain in formulation for such kind of extenders is matrix of the paint must be rich in latex particles.
Spindrift:
The concept behind this method is paint containing dispersed polymeric beads, generally uniform size with maximum diameter of either 5 or 25 μm depending on grade. These beads are made up of copolymers and unsaturated polyesters. The bead contains sealed pores, which gives the large proportions of the total bead volume.
Plastic pigment
The emulsion polymerization prepared particles are used to replace a percentage of titanium dioxide. The non - film forming particles could be varied from 1500-7400 s °A without significant effect on the binder requirement, a balance has to be accepted between the opacity benefit of the finer particles and the film flow benefits.

Opaque polymer
The polyper used in Rohm and Haas technique is non- film forming emulsion polymer with hollow core approximately 0.3 μm in diameter. The inventions had been carried out to reduce the wall size up to 0.05 μrn giving typical hallow sphere 0.4 μm. The acrylic-styrene beads are supplied in emulsion form, at which stage the beads are filled with water. When a paint containing opaque polymer dries, the water permanently diffuses from the core of the particles and is replaced by air, which then acts as fully bound scattering site.
REFERENCES:
LDulux Austrelia Ltd. Matt paints (containing vesiculated polymer granules), Brit. Pat. 1,395,065 Add to 1,288,583.
2. Berger Jenson and Nicholson "Polymer aggregates as pigments and extenders-Ger", 2,747,665 Paint Resin Pat 1978,15(8), abs 790
3.R.W. Andrew and B. Leestraquit, "New additives helps to cut the cost of hiding", Polym. Paint Col., J., 1984, 174, (4122),442 (3PP)
4 Usuki A, Kojima Y, Kawasaki M, Okada A, Fukushima Y, Kaurachi T, Kamigaito O, J. Mater Res, 1993,8(5), 1179-84
5. G.L Li and G.H. Wang, Nanostructure Materials 1996,8,29
6. Yu D Godvaski, Adv polymer Sci 1999,119, 29

EXPERIMENTAL Recipe Formulation
Different recipes (e.g. white under coat and white decorative top coat) were formulated using TiCO2 as major hiding pigment as given under Table 1. The modified recepies incorporated nano particles for partial replacement of TiCO2 at % substitution ranging from 0-70%.
For stage wise replacement of TiO2 by nano extenders, the experiments were designed as indicated in Table 2. For analytical assessment for TiCO2 replacement, the dispersion of above formulation were prepared on pigment Muller and subsequently analyzed for hiding power.
Part I: Synthesis of nano spacing extenders.
It is conducted by in situ matrix deposition by varying salt, substrate ratio from 1:4 to 1:12. The substrate could be water-soluble polymers like PVA, CMC, PEG, and PEO and salt could be water-soluble chlorides, sulphates and nitrates.
Illustration of synthesis of nano calcium carbonate
The complex of calcium chloride with water-soluble polymer was prepared in two different molar ratios (1:4 and 1: 12) in distilled water. An alkali solution was used in second digestion. The first complex was digested for 10-16 hrs and then second complex was added slowly which was subsequently kept for over night digestion. The precipitate was filtered, washed with water and dried in vacuum drier. Nano synthesis by In situ deposition technique is depicted in figure 1. Fig. 2a and b shows XRD scans for calcium carbonate synthesized in low molecular wt water-soluble polymers. XRD scans were utilized for determination of particle size of nano particles.
Part II Preparations of dispersion of Ti02 and nano extenders.
For initial assessment of effect of nano particles as TiCO2 replacers, the micro scale formulations incorporating these nano particles were prepared on digital Muller and subsequently characterized for hiding power and graphical analysis to obtain an

indication of optimum requirement of nano particles for TiO2 replacement. The optimum formulations were then prepared on macro scale (ball mill) and other properties (flexibility, scratch hardness, gloss, durability, chemical resistance etc.) were examined.
1) Digital Pigment Muller:
The Muller was run for 100-300 revolutions under specific load for effective dispersion of pigments and nano particles in binder.
2) Ball Mill:
The optimum formulation was charged in ball mill. The dispersion was carried out for 36 to 72 hrs depending on required fineness of dispersion. A undercoat requires + 6 and topcoat +7 dispersion on hegman scale.
3) Characterization:
i) Hiding power Determination: Hiding power was determined by Moorest
Chart technique, ii) Digital gloss reflectance meter, 45° gloss. It was determined on coated
standard panel with 45° gloss head, iii) Scratch Hardness: Scratch resistance was determined by battery operated
Scratch hardness apparatus.
Graphical Interpretation Example I (nanosize 39 nm)
In all seven micro formulations of under coat and topcoat incorporating 39 nm calcium carbonate prepared by in situ deposition technique at replacement range from 0 to 70 % were prepared. [Refer table 1&2 for formulation details] All 7 runs were conducted on digital Muller. The dispersion was examined for hiding power. The results of the experiments have been presented in table 3 and displayed in graph 3 and 5.

It was observed that the maximum rise in hiding power was around 50% at a TiO2 replacement of 10 to 20%. The results established that 10 to 20 % replacement of TiO2 by nanoparticle was sufficient to cause rise in hiding power almost by 1.5 times.
Example II:
Nanoparticles of 21 nm size were utilized to prepare 7 different formulations of under coat and topcoat as given under table 1&2. The results have been reported in table 3 and illustrated in graph 4 and 6.
Second example have indicated that with drop in nano particle size, nano particles became more efficient as TiO2 replacers and gave maximum hiding power over wider range from 15 to 25 wt %. Smaller nanoparticle size makes formulation less sensitive to concentration of nanoparticles as evidenced by plateau in graph 4 and 6. With coarser nanoparticles, we observe abrupt change in hiding power with slight change in replacement concentration as indicated by presence of peak in graph 3 and 5. Example III
The optimum formulations as determined from variety of runs conducted on Muller were prepared on macro scale in ball mill. The objective was to examine effect of nanoparticles on mechanical and optical properties of undercoat and topcoat. The results have been presented in table 4. These results indicate that nano particles do not have any negative influence over mechanical and optical properties while enhancing hiding power of Paint. In fact it has been observed that nano particles caused more than twice of original hardness. The gloss and flexibility remains unaffected.
Interpretation
Usually there are only 3 interfaces in conventional paint matrix but with incorporation of nano particles, there will be 3 new interfaces due to which the scattering capability of paint increases. The formation of total six interfaces amongst TiO2 -replacers -Binder - Air have been presented schematically in figure 8. The additional interfaces were responsible for dramatic rise in hiding power at replacement level of 10 to 25 % of TiO2.

In entire experiments, the PVC and pigment binder ratios were maintained constant hence the properties, which are influenced by these two parameters, did not alter (for example gloss and flexibility).
Economical aspects of replacement of T1O2
TIO2 is the most significant and expensive component of paint formulation. Usually, there is wide gap between demand and supply of T1O2. Presently TiCO2 is considered to be the sole component contributing to hiding power of paint. Nanotechnology offers utilization of cheap inorganic minerals as partial replacers for TiO2. The overall economics is thus very cost effective made possible by developments in nanotechnology.

Table 1: Formulation parameters of Undercoat and Topcoat

Sr.
No Parameter Formulation 1 (Under coat) Formulation II (Topcoat)
1 PVC 0.25-0.35 0.12-0.18
2 P/B Ratio 1.2-1.6 0.5-0.7
3 %NVM >80 >85
4 Wt / lit 1.5-1.6 1.3-1.4
5 Prime Pigment Rutile TiO2 Rutile TiO2
6 Binder Long Oil Alkyd Long Oil Alkyd
7 Binder solids (%) 60-80 60-80
8 Type of Formulation Under Coat Top Coat
9 Nano particle Size (nm) 10 to 40 10 to 40
10 Nano particle replacement cone. (% TiO2) 0 to 70 0 to 50

Table 2: Design of experiments

Formul ation Size of nanoCaC03 Replacement
of TKD2 by nano
CaC03, wt % No. of experiments Equipment
Recipe 1 39 nm 0 to 70 1 to 6 Muller/ ball mill

21 nm 0 to 70 7 to 13 Muller/ ball mill
Recipe II 39 nm 0 to 50 14 to 20 Muller/ ball mill

21 nm 0 to 50 21 to 27 Muller/ ball mill

Table 3 : Effect of nanosize on hiding power of coating

Size of Nano CaC03 Original
formulation
(without TiO2
replacement)
(cm2/gm) Hiding power, Highest. Corresponding %
replacement of TiO2
by nano CaC03
Formulation I
39 nm 89.87 115.33 11.4
21 nm 89.87 145.15 22.7
Formulation If
39nm 108.64 149.6 16.7
21 nm 108.64 146.6 25.0

Table 4 : Gloss and Scratch hardness of Formulation I with replacement 39 nm CaC03

% replacement by Wt Scratch Hardenss (gm load) Flexibility Digital Gloss
0 200 Pass test on conical mandrel 47
11.4 500
48
22.8 500
47
45.6 500
48
68.4 500
48