|Title of Invention||
"A COMPOSITION OF GRAFTED ETHYLENE PROPYLENE DIENE RUBBER AND POLYVINYL CHLORIDE"
|Abstract||A composition having good weather resistance useful for preparation of automobile articles which comprises of vinyl chloride grafted ethylene propylene diene rubber 10-50 phr, polyvinyl chloride 90-50 phr. Ethylene vinyl acetate copolymer 0.5 to 1 phr, carbon black 0.3 to 0.5 phr, a styrene copolymer 0.5 to 1 phr, conventional polymeric plasticizer 5 to 20 phr, dioctyl phthalate 10 to 50 phr, tetra butyl lead stearate 0.5 to 0.75 phr, dibutyl lead stearate 0.5 to 1.5 phr and stearic acid 0.3 to 0.5 phr.|
|Full Text||This invention relates to a composition of grafted ethylene propylene diene rubber and polyvinyl chloride useful for automobile articles exposed under severe weathering conditions especially with a view to laminate other rubber surfaces devoid of weather resistance. In our copending patent application No .1998/Del/97 we have described and claimed an improved process for the preparation of a poly-vinyl chloride grafted ethylene propylene diene rubber-blend useful for developing compositions for automobile application especially as laminates on rubber surfaces. The compositions have good flow properties and impact resistance. In addition to this, their tensile strength and flexibility is also reasonably good. This composition can be coated upon the other surfaces and when used with a blowing agent mixing followed by polishing and rubbing can give suede like appearance also.
Patent application NO.GB 2, 123, 339 comprises of developing carbon black/color particles containing ethylene propylene diene rubber substrates having a thin layer of smooth or suede like appearance. It was obtained from 75-0% by weight of ethylene propylene diene rubber and 25-100% by weight of a graft copolymer of ethylene propylene diene rubber and vinyl chloride monomer together with the colouring filler and foaming agent. These articles are claimed to be useful as indoor and outdoor materials and other uses. The patent deals with the development of blend using
extrusion moulding followed by vulcanization with or without simultaneous foaming. The dienes incorporated in the rubber used in this example include butadiene and dicyclo-pentadiene. One or more coloring fillers selected from inorganic/organic pigments are also used. The coloring pigments include calcium carbonate, phthalocyanine blue, red oxide, chromium oxide, titanium yellow, benzidene yellow permanent red etc. For plasticizers dioctyl phtha-late, dialkyl phthalates like dimethyl phthalate (DMP), diethyl phthalate (DEP), diisopropyl phthalate etc. have been selected. For suede like appearance, foaming agent is added and coloured and foamed thin layer is polished with an abrasive and skin of the foamed layer is rubbed off to leave the surface with suede like appearance. It is claimed to have excellent weathering resistance, good elasticity against mechanical deformation etc. The weather resistance studies have been carried out after 200 hour irradiation, wherein tensile strength at break and elongation at break retentions have been found to 100 and 95% respectively. The major drawback of the compositions are their weather resistance characteristics after more than 200 hours exposure time hats not been studied. Moreover, their processability does not appear to be evaluated. Also, colouring fillers used here are less efficient than carbon black, because black surface provides improvement in the weathering characteristics of rubber surfaces acting as
ultra violet stabilizer and thereby protecting the blend surface against exposure.
Another patent Japan Kokai Tokkyo Koho JP 57, 126,662 dated August 1982 consists of developing compositions consisting of ethylene - propylene dicyclopentadiene and vinyl chloride monomer grafted ethylene -propylene diene monomer, which are used as weather resistant laminates. Other constituents of the blend prepared include zinc oxide and titanium oxide, dioctyl phthalate, calcined clay, sulphur paraffin oil and diehylene glycol. The weather resistance was evaluated after 200 hours of irradiation; wherein 0% -8% and + 2 points of fall were observed in tensile strength elongation and hardness of the blends. The compositions prepared here have tensile strength around 75 Kg/cm2.
The major draw back of the composition is that their weathering characteristics have not been studied for higher duration, for example, 10 days or higher. Moreover, processability of the composition is also not reported and the composition consists of high percentage of plasticizer. Also, its tensile; strength is not too high.
The main objective of the present invention is to provide a composition of grafted ethylene propylene diene rubber and polyvinyl chloride which obviates the drawbacks as detailed above.
Another objective of the present invention is to provide a composition of ethylene propylene diene rubber and polyvinyl chloride having good weather resistance.
Still another objective of the present invention is to develop a composition which not only has good impact strength but also has reasonably good flexibility and tensile strength.
Yet another objective of the present invention is to develop a composition which has good flow properties and hence an easy processing of the developed blend is ensured.
Yet another objective of the present invention is to develop a composition which has low glass transition temperature such that its mechanical strength at low temperature range is retained.
Accordingly, the present invention provides a composition having good weather resistance useful for preparation of automobile articles which comprises of vinyl chloride grafted ethylene propylene diene rubber 10-50 phr, polyvinyl chloride 90-50 phr. Ethylene vinyl acetate copolymer 0.5 to 1 phr, carbon black 0.3 to 0.5 phr, a styrene copolymer 0.5 to 1 phr, conventional polymeric plasticizer 5 to 20 phr, dioctyl phthalate 10 to 50 phr, tetra butyl lead stearate 0.5 to 0.75 phr, dibutyl lead stearate 0.5 to 1.5 phr and stearic acid 0.3 to 0.5 phr.
The composition obtained by the process of the present invention is neither a product of chemical reaction nor a mere admixture but is a synergistic formulation having properties different than the aggregate properties of the individual components. There is no chemical reaction in the constituents of the said composition.
Blending was carried otu in several steps. The very first step undertaken was to blend the grafted product with additives like stearic acid, tetrabutyl lead stearate, dibutyl lead stearate, styrenene polymer, ethylene vinyl acetate copolymer and carbon black. This was achieved by melt mixing of grafted product and additives on two roll mill. Polybvinyl chloride in yet another step was dry blended with polymeric plasticizer, dioctyl phthalate, dibutyl lead stearate and tetrabutyl stearate. These two blends prepared were then intermixed in various compositions using melt mixing and extrusion techniques. The constituent percentage of the additives were also varied and tested fro their mechanical, dynamic mechanical and weathering characteristics. Thermal decomposition temperature of the bal ends were also evaluated along with their rheological performance for selected composition. Table 1 to 4 record, the various results. The most important advantage of these blend compositions is their high weather resistance. Even after 72 hours of irradiation under extreme weather conditions wherein fixed temperature of 47 ± 3°C and relative humidity 65% was maintained the
percent change in hardness, tensile strength at break and elongation at break were observed to be 0.35% 7.9% and 0.83% respectively. The mechanical strength and flow characteristics are also moderately high. As a result of grafting followed by blending good molecular adhesion, between the two components had led to low temperature strength also. Thermal degradation temperature and weight retention of composition containing 50 phr of grafted ethylene propylene ethylidene norbonene rubber and 50 phr polyvinyl chloride was 246°C and 38.25%.
The following examples are given by way of illustration and the present invention should not be construed to limit the scope of the present invention.
Example - 1
On a preheated two roll mill maintained at a temperature of 40°C; vinyl chloride monomer grafted ethylene propylene ethylidene norbornene rubber, 50 phr; tetrabutyl lead stearate 0.5 phr, dibutyl lead stearate 0.5 phr and stear-ic acid 0.45 phr were melt mixed. In addition to this, 0.2 phr of carbon black, 0.75 phr of a styrene copolymer and 0.5 phr of ethylene vinyl acetate copolymer were also mixed. A thorough milling was carried out and 50 phr of the rubber graft composition was melt mixed by extrusion. It was further mixed with 50 phr dry blended polyvinyl
chloride containing 20 phr dioctyl phthalate and 5 phr polymeric plasticizer that contained 0.1 phr each of both the lead stabilisers. Mechanical strength of prepared composition was determined along with weather resistance. (Table No.1 & 2).
TABLE NO.l MECHANICAL CHARACTERISTICS OF BLEND COMPOSITIONS
TABLE NO.- 2 WEATHER RESISTANCE STUDIES OF BLEND COMPOSITIONS
Example - 2
Polyvinyl chloride 50 phr was dry blended with tetrabutyl lead stearate and dibutyl lead stearate 0.5 phr each in the blender. 10 phr of dioctyl phthalate and 10 phr of polymeric plasticizer was also added to it. A roll mill was preheated to a temperature of 40°C and grafted ethylene propylene ethylidene norbornene rubber melt mixed with tetra butyl lead stearate 0.25 phr dibutyl lead stearate 0.75 phr, stearic acid 0.5 phr styrene copolymer 0.50 phr ethylene vinyl acetate copolymer 0.75 phr and carbon black 0.35 phr. Properly mixed blend (50 phr) was melt mixed and
extrusion blended at 120°C and 150°C with 30 phr composition of dry blended polyvinyl chloride. Mechanical properties of the blend are given in Table No.1.
Example - 3
A properly mixed blend was prepared from 50 phr ethylene propylene ethylidene norbornene rubeer grafted with vinyl chloride monomer, and melt mixed with ethylene vinyl acetate copolymer 0.5 phr, carbon black, 0.5 phr styrene copolymer 0.5 phr, tetrabutyl lead stearate 0.75 phr, dibutyl lead stearate 0.75 phr and stearic acid, 0.5 phr. Polyvinyl chloride was dry blended with 0.25 phr each of dibutyl and tetrabutyl lead stearate. To the composition 50 phr dioctyl phthalate and 20 phr polymeric plasticizer was added. In next step, 50 phr each of the grafted rubber and polyvinyl chloride compositions were melt mixed and extrusion blended to give a composition whose: properties are given in Table Nos. 1 to 4.
TABLE NO. 3 THERMAL CHARACTERISTICS OF BLEND COMPOSITION
TABLE NO. - 4 RHEOLOGICAL CHARACTERISTICS OF BLEND COMPOSITION
Example - 4
On a preheated two roll mill 25 phr of polyvinyl chloride was dry blended with tetrabutyl and dibutyl lead stearate 0.5 ' pbr each, polymeric plasticizer 5 phr and dioctyl phthalate 10 phr. This was melt mixed with blend prepared from intermixing 75 phr grafted vinyl chloride ethylene propylene ethylideiie norbornene rubber, stearic acid 0.5 phr, tetra butyl lead stearate and dibutyl lead stearate 0.25 phr each, ethylene vinyl acetate copolymer 0.75 phr, carbon black 0.25 phr and a styrene copolymer 0.25 phr. Mechanical properties of prepared blends are reported in Table No.1.
1. A composition having good weather resistance useful for preparation of automobile
articles which comprises of vinyl chloride grafted ethylene propylene diene rubber
10-50 phr, polyvinyl chloride 90-50 phr. Ethylene vinyl acetate copolymer 0.5 to 1
phr, carbon black 0.3 to 0.5 phr, a styrene copolymer 0.5 to 1 phr, conventional
polymeric plasticizer 5 to 20 phr, dioctyl phthalate 10 to 50 phr, tetra butyl lead
stearate 0.5 to 0.75 phr, dibutyl lead stearate 0.5 to 1.5 phr and stearic acid 0.3 to
2. A composition having good weather resistance useful for preparation of automobile articles substantially as herein described with reference to the examples.
|Indian Patent Application Number||1864/DEL/1997|
|PG Journal Number||08/2011|
|Date of Filing||04-Jul-1997|
|Name of Patentee||COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH|
|Applicant Address||RAFI MARG, NEW DELHI-110001, INDIA.|
|PCT International Classification Number||C08F 255/06|
|PCT International Application Number||N/A|
|PCT International Filing date|