Title of Invention

A PROCESS FOR THE PREPARATION OF SYNERGISTIC POLYPROPYLENE MOULDING COMPOSITION

Abstract A process for the preparation of synergistic polypropylene moulding composition by mixing and blending polyprolpelene powder in an amount 45 to 72 wt% (w/w) with styrene butadiene styrene copolymer in an amount 4 to 48 wt% (w/w) for at least Vz hour adding and dry blending alkali metal silicate in a ratio of 7 to 24 wt% (w/w) at a temperature of 180 to 190°C extruding at 205°C to obtain strands, chopping to form pallets and drying the pellets at 40°C for 24 hours to obtain the composition.
Full Text This invention relates to a process for the preparation of synergistic polypropylene moulding composition.
More particularly this invention relates to a polypropylene moulding composition having high impact strength, tensile strength and toughness value.
There has been considerable interest in the improvement of properties such as tensile and impact strength in commodity polymers such as polypropylene. The tensile strength of polymers is usually increased by the incorporation of glass fibres. However, this invariably affects the impact strength of polypropylene due to differences in crystallinity and embrittlement at the polymer-fibre interface. It is essential to have very thin fibres in order to increase the aspect ratio when added to the polymer especially as short fibres so as to enhance the properties of the final product. The fibres have to be treated by coupling agents so as to increase the aspect ratio when added to the polymer especially as short fibres so as to enhance the properties of the final product. The fibres have to be treated by coupling agents so as to increase the interfacial adhestion with the polymer matrix. The concentration of the fibres added is usually high which causes deterioration in other properties such as elongation, flexibility and toughness of polypropylene.
There is no prior art for the preparation of polypropylene moulding compound having high impact strength and simultaneously high tensile strength as well as toughness. Our copending patent (2626/DEL/96) describes a process for the preparation of polypropylene compound with high impact strength but it does not lead to improvement of toughness value. Thus there is no prior art for preparation of polypropylene moulding compound having high impact strength, tensile strength and toughness.
The main object of the present invention is therefore to provide a process for the preparation of polypropylene moulding composition having high impact strength, tensile strength and toughness.

Accordingly, the present invention provides a process for the preparation of synergistic polypropylene moulding composition which comprises mixing and blending polyprolpelene powder in an amount 45 to 72 wt% (w/w) with styrene butadiene styrene copolymer in an amount 4 to 48 wt% (w/w) for at least !4 hour adding and dry blending alkali metal silicate in a ratio of 7 to 24 wt% (w/w) at a temperature of 180 to 190°C extruding at 205°C to obtain strands, chopping to form pallets and drying the pellets at 40°C for 24 hours to obtain the composition.
In an embodiment of the present indention, the silicates used is selected from the group consisting of sodium silicate, calcium meta silicate, magnesium silicate, aluminium silicate and a mixture of two or more thereof.
In an embodiment of the present invention, the silicate used is a naturally occurring or synthetic and has a acicular morphology with dimensions in the range of 200 to 3000 micrometer in length and 2 to 20 micro meter in breadth.
In an another embodiment of the present invention, the silicate used has a acicular morphology with dimensions preferably in the range of 1500-2000 micrometer in length and 12 to 15 micrometer in breadth.
In yet another embodiment of the present invention, the thermoplastic elastomer used is based on the diblock or triblock co-polymers containing styrene, butadiene, ester or ether group and is selected from styrene-butadiene-styrene copolymer and co-polyester with polytetrahydrofuran.
In still another embodiment of the present invention, the polypropylene used is a injection moulding or extrusion grade having the MFI in the range of 2 to 20 gm/min, preferably 5 to 8 gm/min.
In still another embodiment of the present
invention, the polypropylene used is a injection

moulding or extrusion grade having the MFI in the range of 2 to 20 g/min preferably
5 to 8 g/min.
In still another embodiment of the present invention, the polypropylene grAiules with the
silicate is preferably 15 wt%.
In still another embodiment of the present invention, the concentration of the thermoplastic
elastomer added is preferably 30 wt%.
In a feature of the present invention, in the preferred range of compositions, the
polypropylene moulding compound prepared according to the present invention and
injection moulded under standard conditions of feed temperature 180°, melt temperature
205°C, pressure 1905 bar, mould temperature 26°C, gave a product having impact strength 4
times , tensile 1.4 times and toughness 1.6 times the original value without the additives.
The invention is described hereinbelow by the following examples, which are illustrative
only and should not be construed to limit the scope of the invention in any manner.
EXAMPLE - 1
Indian Wollastonite, calcium metasilicate, having acicular morphology and average dimensions of 140 micrometer in length and 6 micrometer in breadth,(20 gms) was mixed with 200 gms of polypropylene (MFI 8 to 10) in a dry blender for 1/2 hr. To this were added 60 gms of triblock styrene- butadiene - styrene co-polymer having 20% styrene content and further dry blended for 1/2 hr. The whole mixed polyprolpylene was fed to a plasticorder single screw extruder held at 180°C to 190°C and extruded at the nozzle temperature of 205°C to obtain strands, which were chopped to form pellets of the polypropylene moulding compounds. The modified polypropylene compounded pellets were dried at 40°C for 24 hrs

and then injection moulded under standard conditions (feed temperature 180°C, mid zone temperature 190° C to 195° C and exit zone at 205° C, mould temperature 26° C and pressure of 1905 bars) to give polypropylene mouldings having high impact and high tensile strength. The properties of these mouldings are given in Table - 1.
EXAMPLE - 2
Polypropylene powder (MFI 8 to 10 g /min) 125 gms was mixed with 83.7 gms of triblock
* styrene-butadiene-styrene co-polymer in a dry blender for 1/2 hr. To this were added
chopped sodium silicate glass fibres (41.75 gms) having average dimensions of 5 mm length and 15 micrometer diameter. This was thoroughly mixed in the dry blender for 1/2 hr. The mixed polypropylene was extruded in the plasticorder single screw extruder, the extrudate cut to size, dried and then injection moulded under the same conditions as described in Example - 1. The properties of these mouldings are given in Table - 1.
EXAMPLE - 3
Polypropylene (MFI 8 to 10) granules (125 gms) were mixed with 83.75 gms of styrene-butadiene-styrene triblock co-polymer having styrene content of 30 % and dry blended in a mixer. To this were added chopped sodium silicate glass fibres (62.6 gms) having average dimensions of 3mm length and 15 micrometer diameter. This mixed polypropylene was then extruded in a plasticorder single screw extruder, extrudate cut to size, dried and injection moulded in the same manner as described in the Example - 1. The properties of these mouldings are given in Table-1.

Table-l
(Table Removed)

It is seen from the values given in the Table - 1, that the impact strength, tensile modulus as well as the toughness improved considerably in the case of modified polypropylene moulding compound prepared by the process described in the present invention as compared to the the original material. The impact strength is improved by 2 to 4 times, tensile strength is increased by 1.5 to 2 times and the toughness is increase by 1.6 times in the moulding compound prepared according the present invention as compared to the original.





We claim :
1. A process for the preparation of synergistic polypropylene moulding
composition which comprises mixing and blending polyprolpelene powder in
an amount 45 to 72 wt% (w/w) with styrene butadiene styrene copolymer in
an amount 4 to 48 wt% (w/w) for at least 1/2 hour adding and dry blending
alkali metal silicate in a ratio of 7 to 24 wt% (w/w) at a temperature of 180
to 190°C extruding at 205°C to obtain strands, chopping to form pallets and
drying the pellets at 40°C for 24 hours to obtain the composition.
2. A process as claimed in claim 1 wherein the alkali metal silicates used is
selected from the group consiting of sodium silicate, calcium meta silicate,
magnesium silicate, aluminium silicate and a mixture of two or more
thereof.
3. A process as claimed in claims 1-2 wherein the alkali metal silicate used is
a naturally occurring or synthetic and has a acicular morphology with
dimensions in the range of 200 to 3000 micrometer preferably in the range
of 1500 to 2000 micrometer in length and 2 to 20 micro meter preferably in
the range of 12 to 15 micrometer in breadth.
4. A process as claimed in claims 1-3 wherein the thermoplastic elastomer
used is based on the diblock or triblock co-polymers containing styrene,
butadiene, ester or ether group and is selected from styrene-butadiene-
styrene-butadiene-styrene copolymer and co-polyester with
polytetrahydrofuran.

5. A process as claimed in claims 1-4 wherein the polypropylene granules with
silicate is preferably 15 wt%.
6. A process as claimed in claims 1-5 wherein the concentration of
thermoplastic elastomer added is preferably 30 wt%.
7. A process for the preparation of synergistic polypropylene moulding
composition substantially as herein described with reference to the
examples.

Documents:

93-del-2001-abstract.pdf

93-del-2001-claims.pdf

93-del-2001-correspondence-others.pdf

93-del-2001-correspondence-po.pdf

93-del-2001-description (complete).pdf

93-del-2001-form-1.pdf

93-del-2001-form-19.pdf

93-del-2001-form-2.pdf


Patent Number 230368
Indian Patent Application Number 93/DEL/2001
PG Journal Number 11/2009
Publication Date 13-Mar-2009
Grant Date 26-Feb-2009
Date of Filing 31-Jan-2001
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110 001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 SUBRAMANIAM RADHAKRUSHNA FROM NATIONAL CHEMICAL LABORATORY, PUNE-411008,(MAHARASHITRA) INDIA
2 COMANDUR SAUJANYA, India Maharashtra India
PCT International Classification Number C08L 23/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA