Claims:
1. A melt sheet composition comprising phosphate sludge, polymer, filler, extender, dehydrant, plasticizer and reinforcement material.

2. The composition as claimed in claim 1, wherein
the polymer is selected from acrylic polymer, alkyd polymer, epoxy polymer bitumen, latex, ethylene vinyl acetate (EVA) or combination thereof,
the filler is selected from calcium carbonate, glass, polymer foam beads, mineral powder or combination thereof,
the extender is selected from TSRN1067, clay, talc, zinc oxide, mica or combination thereof,
the dehydrant is selected from methanol, ethanol, isopropyl alcohol, acetone, calcium oxide or combination thereof,
the plasticizer is selected from dioctyl phthalate (DOP), acetyl tributyl citrate (ATBC), diisononyl adipate (DINA) aromatic rubber process oil or combination thereof, and
the reinforcement material is cotton fibers.

3. The composition as claimed in claim 1, wherein the phosphate sludge is up to 10% w/w.

4. The composition as claimed in claim 2 comprising 20%-45% w/w of bitumen, 1%-5% w/w of latex, 0.1%-2% w/w of ethylene vinyl acetate, 2%-4% w/w of phosphate sludge, 20%-50% w/w of calcium carbonate, 18%-36% w/w of mineral powder, 5%-30% w/w of mica, 5%-15% w/w of calcium oxide, 0.1%-1% w/w of aromatic rubber process oil, and 0.5%-2% w/w of cotton fibers.

5. A process for preparation of a melt sheet composition comprising,
obtaining phosphate sludge from a paint shop process such as cathodic electro deposition (CED) process; and
mixing phosphate sludge, polymer, filler, extender, dehydrant, plasticizer and reinforcement material.

6. The process as claimed in claim 5, wherein the phosphate sludge is dried and optionally powdered.

7. The process as claimed in claim 5, wherein phosphate sludge is up to 10% w/w.

8. The process as claimed in claim 7, comprising 20%-45% w/w of bitumen, 1%-5% w/w of latex, 0.1%-2% w/w of ethylene vinyl acetate, 2%-4% w/w of phosphate sludge, 20%-50% w/w of calcium carbonate, 18%-36% w/w of mineral powder, 5%-30% w/w of mica, 5%-15% w/w of calcium oxide, 0.1%-1% w/w of aromatic rubber process oil, and 0.5%-2% w/w of cotton fibers.

9. A process for preparation of a melt sheet comprising:
calendaring the composition as claimed in any one of claims 5-8; and
applying an anti-stick coating.

10. The process as claimed in claim 9, wherein the sheet is dried after application of the anti-stick coating.
, Description:

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

A MELT SHEET COMPOSITION AND A PROCESS FOR PREPARATION THEREOF

MAHINDRA & MAHINDRA LIMITED, A COMPANY REGISTERED UNDER THE INDIAN COMPANIES ACT, 1913, HAVING ADDRESS AT MAHINDRA RESEARCH VALLEY (MRV), MAHINDRA WORLD CITY, PLOT NO: 41/1, ANJUR P.O., CHENGALPATTU – 603004, KANCHEEPURAM DIST., TAMIL NADU, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to a melt sheet composition comprising phosphate sludge and a process for its preparation.

BACKGROUND OF THE INVENTION
In Universal painting process, before final painting, PT-CED (pre-treatment cathodic electro deposition) process is done on the vehicle bodyshell to protect the base material from corrosion. This process uses zinc phosphate. During processing of zinc phosphate, due to chemical reaction an insoluble precipitant known as phosphate sludge is produced.

The phosphate sludge is an undesirable and hazardous waste by-product in zinc phosphate process from the paint shop operation (PT-CED) on bodyshell for the aesthetic purpose and to provide corrosion resistance to surfaces. The disposal of the phosphate sludge is cost-intensive. Approximately 60 tonnes of sludge per annum is disposed as landfill which results in deterioration of agricultural land and results in land pollution.

There is a need for recycling the phosphate sludge to support the environment and to reduce the sludge from being disposed into landfills, thereby preventing damage to agricultural land and also reduce the cost associated with its disposal.

SUMMARY OF INVENTION
In an aspect, the invention relates to a melt sheet composition comprising phosphate sludge, polymer, filler, extender, dehydrant, plasticizer and reinforcement material.

In another aspect, the invention relates to a process of preparing a melt sheet composition.

BRIEF DESCRIPTION OF DRAWING
Figure 1: illustrates a flow diagram of process steps involved in the preparation of a melt sheet composition and a sheet comprising the composition.

Figure 2: illustrates (a) Melt sheet invention; (b) Pictorial representation of the sheet applied on the floor of the vehicle body.

DETAILED DESCRIPTION OF THE INVENTION
The invention addresses the need of recycling of phosphate sludge produced in paint shop operation by incorporating phosphate sludge as a component in a melt sheet composition.

In an aspect, the invention relates to a melt sheet composition comprising phosphate sludge, polymer, filler, extender, dehydrant, plasticizer and reinforcement material.

The polymer is selected from acrylic polymer, alkyd polymer, epoxy polymer bitumen, latex, ethylene vinyl acetate (EVA) or combination thereof.

The filler is selected from calcium carbonate, glass, polymer foam beads, mineral powder or combination thereof.

The extender is selected from TSRN1067 (Brite), clay, talc, zinc oxide, mica or combination thereof.

The dehydrant is selected from methanol, ethanol, isopropyl alcohol, acetone, calcium oxide or combination thereof.

The plasticizer is selected from dioctyl phthalate (DOP), citrates such as acetyl tributyl citrate (ATBC), adipates such as diisononyl adipate (DINA), aromatic rubber process oil such as Elasto 710 or combination thereof.

The reinforcement material is a fiber such as cotton fibers.

The composition comprises up to 10% w/w of phosphate sludge.

The composition comprises 20%-45% w/w of bitumen, 1%-5% w/w of latex, 0.1%-2% w/w of ethylene vinyl acetate, 2%-4% w/w of phosphate sludge, 20%-50% w/w of calcium carbonate, 18%-36% w/w of mineral powder, 5%-30% w/w of mica, 5%-15% w/w of calcium oxide, 0.1%-1% w/w of aromatic rubber process oil, and 0.5%-2% w/w of cotton fibers.

In another aspect, the invention relates to a process for preparing the melt sheet composition. The process comprises obtaining phosphate sludge from a paint shop process such as cathodic electro deposition (CED) process. The phosphate sludge is then mixed with polymer, filler, extender, dehydrant, plasticizer and reinforcement material.

The phosphate sludge from the paint shop operation is subjected to drying, optionally powdering and mixing with the other ingredients such as polymer, filler, extender, dehydrant, plasticizer and reinforcement material to form the sheet composition.

The process comprises up to 10% w/w of phosphate sludge.

The polymer, filler, extender, dehydrant, plasticizer and reinforcement material are described above.

The process for preparation of the sheet composition comprises 20%-45% w/w of bitumen, 1%-5% w/w of latex, 0.1%-2% w/w of ethylene vinyl acetate, 2%-4% w/w of phosphate sludge, 20%-50% w/w of calcium carbonate, 18%-36% w/w of mineral powder, 5%-30% w/w of mica, 5%-15% w/w of calcium oxide, 0.1%-1% w/w of aromatic rubber process oil, and 0.5%-2% w/w of cotton fibers.

The recycling of phosphate sludge as a component of the melt sheet composition completely eliminates the disposal of the phosphate sludge into landfill, thereby preventing degradation of agricultural land caused by the phosphate sludge landfills and reducing its impact on the environment. The recycling of the phosphate sludge also reduces or eliminates the cost associated with its disposal.

The invention also relates to a process for preparation of a sheet from the melt sheet composition. The process comprises calendering the melt sheet composition to form a sheet. An anti-stick coating of a fatty acid based compound such as available under the tradename Aurosap is applied on the sheet and then the sheet is dried. The anti-stick coating prevents sticking of sheets when stacked over each other. The sheet is subjected to blanking and profiling to provide a desired shape to the sheet.

The sheet has high strength, better adhesion properties, lower volatile matter and provides improved dampening of noise (sound) having frequency of 200 Hz to 800 Hz and vibration from the vehicle.

The sheets are spread on the floor of the body of the vehicle at various locations as per the vehicle design. The sheet gets fused with floor of the vehicle body while the vehicle body is baked in an oven for baking the paint applied on it.

Examples

Example 1
Melt Sheet Composition
The phosphate sludge was obtained from the paint shop process, dried and powdered if required.

The melt composition was prepared by mixing the dried phosphate sludge, polymer, filler, extender, dehydrant, plasticizer and reinforcement material. Table 1 shows the formulations of the melt sheet composition of the present invention.

Table 1
Quantity (% w/w)
Ingredients Sample 1 Sample 2 Sample 3 Sample
4 Standard Melt Sheet
Bitumen 40 22.5 26 35 --
Latex 5 2 3 3 --
Ethylene vinyl acetate 2 1 0.5 1.5 1.5
Phosphate sludge 2 3 4 4 0
Calcium carbonate 20 25 20.9 20 23.5
Mineral powder 18 25 20 20 20
Mica 5 10 10 10 10
Calcium oxide 5 10 15 5 5
Aromatic rubber process oil (Elasto 710) 1 0.5 0.1 0.5 1
Cotton Fibers 2 1 0.5 1 1

Example 2
Melt Sheet
The composition described in Example 1 was calendared into a melt sheet having an envelope size ranging from 1000 mm x 300 mm, 300 mm x 90 mm, 435 mm x 175 mm, 700 mm x 350 mm etc. An anti-stick coating (Aurosap) was applied on the sheet followed by drying. The sheet was subjected to blanking and profiling to provide a desired shape to the sheet. The process for preparation of the melt sheet is outlined in Figure 1. The prepared melt sheet is shown Figure 2a.

The sheets were placed on the floor of the vehicle body as shown in Figure 2b. The vehicle body was baked in an oven to fuse the sheets with floor of the vehicle body.

Evaluation of the Melt sheet
The properties of melt sheet were determined and compared against standard melt sheet without phosphate sludge as shown in Table 2.
Table 2
No. Property (unit) Specification Standard Melt Sheet Sample 4 of the present invention
1 Density (g/cc) 1.60±0.2 1.76 1.80
2 Thickness (mm) 2.0±0.2 1.96 2.03
3 Adhesion on Glass Panel (%) > 50 87 92
4 Co-efficient of filler (%) < 65 54.15 52.26
5 Volatile Matter (%) < 0.6 0.26 0.10
6 Sinking (Sagging) (mm) > 6.0 14.63 18.62
7 Thermal Flow Resistance (Heat Flow) (mm) To be Free from running out and 15.0 mm in Flow Down 1 1
8 Contraction Rate (%) < 3.0 2.32 1.96
9 Loss factor > 0.08 at 20°C 0.120 at 20°C 0.122 at 20°C
10 Cold Impact Resistance No Abnormalities allowed No crack and Peel off
11 Flammability (mm/min) < 80 No Burn Rate
12 Shear Strength (Kpa) > 500 762 879
13 Pull strength (Kgf/mm2) > 8 13.33 13.81
14 Elongation at break (%) > 15 22.53 18.28
15 Odour Free from any
objectionable odour No Objectionable odour found

As seen from the table, melt sheet comprising the composition of the present invention met the set specification for the properties. The melt sheet had better adhesion on glass panel, higher sinking (sagging), lower volatile matter, lower contraction rate and high shear strength than the standard melt sheet. The higher sinking indicated that the melt sheet comprising phosphate sludge had better flowability of material. The lower contraction rate indicates that the change in the dimension of the melt sheet comprising phosphate sludge was less when subjected to heat. The reduced amount of volatile matter in the melt sheet of the present invention is advantageous as less volatile material would be released during working with the sheet in the press shop. This provides a security of life for the operator working in press shop around such high tonnage presses.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.