Title of Invention

POLYOLEFIN RESIN COMPOSITIONS WITH LOW HAZE AND REDUCED SHRINKAGE ANISOTROPY

Abstract

The invention relates to a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nanoclay and about 1000 to 2000 ppm of a nucleating agent, the nano-clay and the nucleating agent being present in the composition in a total amount of 2000 ppm. The invention also relates to a method for preparing the composition the method comprising blending in a twin-screw extruder at a temperature in the range of 150°C to 250°C at a specific energy in the range of 0.1 to 2.5 kilo watt hr/kg.

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) As amended by the Patents (Amendment) Act, 2005 & THE PATENTS RULES, 2003 As amended by the Patents (Amendment) Rules, 2006 COMPLETE SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION Polyolefin Resin Compositions with Low Haze and Reduced Shrinkage Anisotropy APPLICANT RELIANCE INDUSTRIES LIMITED, 5th Floor, Maker Chamber IV, Nariman Point,Mumbai 400 021, Maharashtra, India, an Indian Company INVENTORS Dr Shyamroy Subarna and Dr Preschilla Nisha, both Indian Nationals of Reliance Industries Ltd, Product Application & Research Centre, R&D, PRTC (M&ER), Swastik Mill Compound, V N Purav Marg, Chembur, Mumbai -400071, Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the nature of this invention and the manner in which it is to be performed: Field of invention The invention relates to a polyolefin resin composition having low haze and reduced shrinkage anisotropy. The invention also relates to a method for preparing the composition and to the articles prepared thereof. Background Polyolefins are used in a variety of applications that require enhanced physical and optical properties. In many such applications, the polyolefin is required to be resistant to warpage and need to have high clarity. Resistance to warpage is largely determined by the shrinkage anisotropy values (measured as the ratio of shrinkage in the machine direction to the shrinkage in the transverse direction) of the polyolefin while the clarity of the polyolefin is determined by the values of percentage haze. Conventionally, nucleating agents are used to reduce the haze or the shrinkage anisotropy. However, the conventional nucleating agents, especially, those nucleating agents which are used for reducing shrinkage anisotropy, are expensive. In comparison, nanoclays are less expensive and are also known to act as nucleating agents in polyolefin compositions at loadings higher than 50000 ppm. At such loadings of nanoclay, however, the haze of polyolefin compositions tend to increase. There is a need for polyolefin resin compositions having a combination of low haze and shrinkage anisotropy. Detailed description 2 Accordingly, the invention provides a polyolefin resin composition comprising about 1 to 1000 ppm of an organically modified nanoclay and 1000 to 2000 ppm of a nucleating agent, the total amount of nanoclay and nucleating agent being 2000 ppm, the composition having a unique combination of low haze and reduced shrinkage anisotropy. When used throughout this specification, the following terms have the meanings indicated: The term "shrinkage anisotropy" as used herein refers to the ratio of shrinkage in the machine direction to the shrinkage in the transverse direction . The term "nanoclay" as used herein refers to clays having individually nano sized layers. In one embodiment, the invention provides a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nanoclay and about 1000 to 2000 ppm of a nucleating agent, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm. In another embodiment, the invention provides a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nanoclay and about 1000 to 2000 ppm of a nucleating agent, the nanoclay and the nucleating agent being present 3 in the composition in a total amount of 2000 ppm wherein the nucleating agent is an inorganic salt of an organic acid. In another embodiment, the invention provides a polyolefm resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefm dispersed with about 1 to 1000 ppm of an organically modified nanoclay and about 1000 to 2000 ppm of a nucleating agent, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm wherein the nucleating agent is an organic clarifying agent. In another embodiment, the invention provides a polyolefm resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefm dispersed with about 1 to 1000 ppm of an organically modified nanoclay, about 2000 to 1000 ppm of a nucleating agent and a compatibilizer, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm In another embodiment, the invention provides a polyolefm resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefm dispersed with about 1 to 1000 ppm of an organically modified nanoclay, about 1000 to 2000 ppm of a nucleating agent and a polypropylene grafted with anhydride of an unsaturated dibasic organic carboxylic acid, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm 4 In another embodiment, the invention provides a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nanoclay, about 1000 to 2000 ppm of a nucleating agent and a polypropylene grafted with anhydride of maleic acid, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm In another embodiment, the invention provides a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nanoclay, about 1000 to 2000 ppm of a nucleating agent and a polypropylene grafted with anhydride of an unsaturated dibasic organic carboxylic acid, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm, the composition having a having a haze less than 16 % measured using a polyolefin plaque having a thickness of lmm and a haze less than 34 % measured using a polyolefin plaque having a thickness of 2mm. In another embodiment, the invention provides a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nanoclay, about 1000 to 2000 ppm of a nucleating agent and a polypropylene grafted with anhydride of an unsaturated dibasic organic carboxylic acid, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm, the composition having 5 shrinkage anisotropy in the range of 0.97 to 1.0 and having a having a haze less than 16 % measured using a polyolefin plaque having a thickness of 1mm and a haze less than 34% measured using a polyolefin plaque having a thickness of 2mm. In another embodiment, the invention provides a method for preparing a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the method comprising blending in a twin-screw extruder at a temperature in the range of 150°C to 250°C at a specific energy in the range of 0.1 to 2.5 kilo watt hr/kg. In a further embodiment, the invention provides articles prepared from a polyolefin resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefin dispersed with about 1 to 1000 ppm of an organically modified nano-clay, about 1000 to 2000 ppm of a nucleating agent and a polypropylene grafted with anhydride of an unsaturated dibasic organic carboxylic acid, the nanoclay and the nucleating agent being present in the composition in a total amount of 2000 ppm The invention provides a polyolefin composition comprising organically modified nano-clay in loadings as less as 1 to 1000 ppm in synergistic combination with 1000 to 2000 ppm of a nucleating agent, the nanoclay and the nucleating agent totaling 2000 ppm with respect to the polyolefin weight being dispersed in the polyolefin matrix. Due to the synergistic association of the nanoclay and the nucleating agent in the polyolefin, there is reduction in shrinkage anisotropy, maintaining a low value of haze. 6 The examples of polyolefins used to prepare the compositions of the invention include, but are not limited to, homo polymers and random copolymers of olefins. The nanoclays suitable for preparing composition of the invention include, but are not limited to montmorillonite, bentonite, kaolinite, hectorite, fluorohectorite, saponite, beidelite, nontronite, stevensite, vermiculite, hallosite, volkonskoite, suconite, magadite, and kenyalite. The nanoclay used for preparing the compositions of the invention is usually organically modified. The examples of organic modifiers include, but are not limited modifiers having the formula: +N*R1R2R3R4 wherein: R1, R2, R3 and R4 are independently selected from a group consisting of a saturated or unsaturated C1 to C22 hydrocarbon, substituted hydrocarbon and branched hydrocarbon. Examples of groups represented by R1, R2, R3 and R4 include saturated or unsaturated alkyls, including alkylenes; substituted alkyls such as hydroxyalkyls, alkoxyalkyl, alkoxys, amino alkyls, acid alkyls, halogenated alkyls, sulfonated alkyls, nitrated alkyls and the like; branched alkyls; aryls and substituted aryls, such as alkylaryls, alkoxyaryls, alkylhydroxyaryls, alkylalkoxyaryls and the like. Optionally, one of R1, R2, R3 and R4 is hydrogen. The nucleating agents used for preparing the compositions of the invention include, but are not limited to organic clarifying agents and inorganic salts of organic acids. The examples of organic clarifying agents include, but are not limited to amides, acetals, alcohols, polynuclear aromatics and organic gelator molecules. The examples of salts of organic acids used as nucleating agents in the composition of the invention include 7 carboxylic acid salts, sulphonic acid salts, phosphoric acid salts, sulphinic acid salts, phosphinic acid salts and the like. When an inorganic salt of an organic acid is used as the nucleating agent, polyolefin compositions having a haze less than 16% measured using a polyolefin plaque having a thickness of 1mm and a haze less than 34% measured using a polyolefin plaque having a thickness of 2mm are formed. When an organic clarifying agent is used as the nucleating agent polyolefin compositions having haze less than 10% measured using a polyolefin plaque having a thickness of 1mm and a haze less than 24% measured using a polyolefin plaque having a thickness of 2 mm are formed. The invention provides polyolefin resin compositions comprising minimal amount of conventional nucleating agent and selected amount of organically modified nanoclay. It is surprisingly observed that at low loadings of nanoclay and nucleating agent, the properties of polyolefin are synergistically improved. Particularly, the polyolefin haze is kept low and the shrinkage anisotropy is reduced to the desirable range. Thus the compositions of the invention enable to provide clarified polyolefins having reduced warpage at significantly low cost. In the experiment/results that follow, the percentage haze was determined by standard ASTM D1003 method. Glass transition temperature was measured by differential scanning calorimetry (DSC). Flexural modulus is measured by standard ASTM D790 method. Shrinkage anisotropy was determined from injection molded ISO D2 plaques. Melt flow index (MFI) was determined by standard ASTM D1238 method. 8 The invention is further illustrated by way of the following example. Example 1 Calculated amount of tetra alkyl ammonium modified montmorillonite and the conventional nucleating / clarifying agents are added separately to a stock of PPRCP (polypropylene random copolymer with 3% ethylene content in the backbone), fluff (powder from the reactor) of MFI 12.00 dg/min stabilized with the appropriate commercial stabilizer package. Whenever required, appropriate amounts of maleic anhydride-grafted PP (compatibilizer between PP and nanoclay) are added optionally to the formulations. The powder formulations as described above are tumbled for 15 - 30 min for uniform physical mixing followed by compounding and molding like PPRCP with a conventional nucleating or clarifying agent. The compositions prepared as above are injection molded into plaques of desired thickness in order to measure the various parameters. The properties of the different polypropylene compositions comprising varying amounts of nucleating agents and nanoclay are displayed in table 1. 9 Table 1: Comparison of properties of polypropylene compositions containing varying proportions of nanoclay and nucleating agent Nucleating agent Amount of nucleatin g agent (ppm) Amount of tetra- alkyl ammoni urn modifie d montmo rilonite (ppm) Percentage haze at 1 mm+++ Percentag e haze at 2 mm++++ Glass transit ion tempe rature ,TC (°C) Melting tempera ture, Tm (°C) T -T 1M l c Flexural modulus (MPa) Shrinka ge anisotro py MD/TD MFI (dg/min ) NA-21+ 2000 0 15.54 33.27 117.0 0 152.70 35.70 1025 0.899 11.50 1500 500 15.15 33.20 116.7 0 151.00 34.30 1055 0.976 10.80 1000 1000 15.38 33.27 116.3 0 149.70 33.40 1070 0.973 11.30 0 2000 55.63 81.20 104.3 0 146.70 42.40 875 0.988 11.20 M3988++ 2000 0 9.85 23.32 119.7 0 156.40 36.70 990 0.935 12.50 1500 500 9.76 23.34 119.0 0 155.00 36.00 1005 0.996 11.70 1000 1000 9.88 23.16 117.3 0 152.40 35.10 975 0.986 12.00 0 2000 58.21 81.39 100.3 0 149.00 48.70 840 0.996 11.20 +auminium salt of a phosphonic acid (inorganic salt of organic acid) +3,4-dimethyl bezylidene acetal of sorbitol (organic nucleating agent) +++ The percentage haze as measured using a polypropylene plaque having thickness of lmm ++++ The percentage haze as measured using a polypropylene plaque having thickness of 2mm From table 1, it is clear that polypropylene compositions of the invention have a low haze value, the haze value being comparable to that of the polypropylene composition having 2000 ppm of nucleating agent alone. Therefore, in the compositions of the invention the 10 organically modified nano-clay replaces the nucleating agent retaining the haze (as evident from column 3 of table 1). Such retention of the haze value on addition of the nano-clay, is indicative of the synergy displayed by the nanoclay and the nucleating agent in the compositions of the invention. Nanoclay is known to deteriorate the haze and consequently an increase in the haze value was expected upon removal of nucleating agent and compensating the removal by the addition of an organically modified nano-clay. The synergy is further illustrated in Figure 1 and Figure 2 of the accompanying drawings. Figure 1 show the variation of haze value with addition of NA-21 as the nucleating agent independently (represented by the variation described as NA-21 alone) as well as by replacing the nano-clay (represented by the variation described as NA-21 with (2000-x) ppm of NC). Figure 2 show the variation of haze value with addition of M3988 as the nucleating agent independently (represented by the variation described as M3988 alone) as well as by replacing the nano-clay (represented by the variation described as M3988 with (2000-x) ppm of NC). A steep decrease in haze value is observed by the independent addition of nucleating agent from an amount of 500 ppm to 2000 ppm to the polypropylene resin. Therefore a steep increase of haze was expected for a composition where the nucleating agent is replaced by the nano-clay (NC). However, in the case of both the nucleating agents , namely, NA-21 and M3988, the haze value is retained when the nucleating agent is replaced, in the same quantity, by a nano-clay. The observed retention of haze value of polypropylene containing nano-clay as well as the nucleating agent (in amounts ranging from 500 to 1500 ppm) compared to the polypropylene containing the nucleating agent alone, is advantageous and renders the polyolefin compositions cost efficient. Further, the compositions of the invention provide 11 polyolefin having reduction in shrinkage anisotropy, the shrinkage anisotropy values being close to unity. The reduction in shrinkage anisotropy measures reduction in warpage and the reduction in warpage results in lesser rejects in the molded parts at a molder's site. Consequently, efficiency of molding operations as well as quality of the polyoefin products are improved. Further, the reduced Tm - Tc values for the composition of the invention suggests efficient nucleation that results in faster crystallization which in turn increases the productivity of the polyolefin product. Furthermore, from table 1 it is clear that the MFI, flexural modulus, melting point and crystallization temperature of the polyolefin is not significantly affected indicating that no significant structural or chemical changes have occurred and that the rheological and mechanical properties of the polyolefin are not affected by the addition of nucleating agent and nanoclay. The above description is illustrative only and is not limiting. The present invention is defined by the claims that follow and their full range of equivalents. 12 We Claim: 1) A polyolefm resin composition having low haze and reduced shrinkage anisotropy, the composition comprising polyolefm dispersed with about 1 to 1000 ppm of an organically modified nanoclay and about 1000 to 2000 ppm of a nucleating agent, the nano-clay and the nucleating agent being present in the composition in a total amount of 2000 ppm. 2) The composition as claimed in claim 1, wherein the nucleating agent is an organic clarifying agent. 3) The composition as claimed in claim 1 wherein the nucleating agent is an inorganic salt of an organic acid. 4) The composition as claimed in anyone of the claims 1 to 3 additionally comprising a compatibilizer 5) The composition as claimed in claim 4, wherein the compatibilizer is a polypropylene grafted with anhydride of an unsaturated dibasic organic carboxylic acid. 6) The composition as claimed in claim 5, wherein the dibasic acid is maleic acid 13 7) The composition as claimed in any one of claims 1 to 6 having a haze less than 16 % measured using a polyolefin plaque having a thickness of 1mm and a haze less than 34 % measured using a polyolefin plaque having a thickness of 2mm. 8) Polyolefin compositions as claimed in any one of the claims 1 to 7 having shrinkage anisotropy in the range of 0.97 to 1.0 9) A method for preparing the composition as claimed in claim 1, the method comprising blending in a twin-screw extruder at a temperature in the range of 150°C to 250°C at a specific energy in the range of 0.1 to 2.5 kilo watt hr/kg. 10) Articles prepared from the composition as claimed in any one of the claims 1 to 8 Dated this 3rd day of June 2008 (Dr Shilpa Gharve) Of Khaitan&Co Agent for the Applicants 14

Documents:

1175-MUM-2008-ABSTRACT(GRANTED)-(22-5-2012).pdf

1175-mum-2008-abstract.doc

1175-mum-2008-abstract.pdf

1175-MUM-2008-CANCELLED PAGES(20-12-2011).pdf

1175-MUM-2008-CLAIMS(AMENDED)-(20-12-2011).pdf

1175-MUM-2008-CLAIMS(AMENDED)-(27-4-2012).pdf

1175-MUM-2008-CLAIMS(GRANTED)-(22-5-2012).pdf

1175-MUM-2008-CLAIMS(MARKED COPY)-(20-12-2011).pdf

1175-MUM-2008-CLAIMS(MARKED COPY)-(27-4-2012).pdf

1175-mum-2008-claims.doc

1175-mum-2008-claims.pdf

1175-MUM-2008-CORRESPONDENCE 13-6-2008.pdf

1175-MUM-2008-CORRESPONDENCE 8-7-2008.pdf

1175-MUM-2008-CORRESPONDENCE(13-4-2012).pdf

1175-MUM-2008-CORRESPONDENCE(IPO)-(22-5-2012).pdf

1175-mum-2008-correspondence.pdf

1175-mum-2008-description(complete).doc

1175-mum-2008-description(complete).pdf

1175-MUM-2008-DESCRIPTION(GRANTED)-(22-5-2012).pdf

1175-MUM-2008-DRAWING(GRANTED)-(22-5-2012).pdf

1175-mum-2008-drawing.pdf

1175-MUM-2008-FORM 1 13-6-2008.pdf

1175-mum-2008-form 1(13-6-2008).pdf

1175-MUM-2008-FORM 1(20-12-2011).pdf

1175-mum-2008-form 1.pdf

1175-MUM-2008-FORM 13(20-12-2011).pdf

1175-MUM-2008-FORM 18 8-7-2008.pdf

1175-MUM-2008-FORM 2(GRANTED)-(22-5-2012).pdf

1175-MUM-2008-FORM 2(TITLE PAGE)-(20-12-2011).pdf

1175-MUM-2008-FORM 2(TITLE PAGE)-(GRANTED)-(22-5-2012).pdf

1175-mum-2008-form 2(title page).pdf

1175-mum-2008-form 2.doc

1175-mum-2008-form 2.pdf

1175-mum-2008-form 26(13-6-2008).pdf

1175-mum-2008-form 3.pdf

1175-MUM-2008-REPLY TO EXAMINATION REPORT(20-12-2011).pdf

1175-MUM-2008-REPLY TO HEARING(27-4-2012).pdf

1175-MUM-2008-URDIP SEARCH REPORT(29-9-2010).pdf

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