Title of Invention

CONTROLLED BRANCHED POLYESTER AND PROCESS FOR MAKING THE SAME

Abstract

A process for making thermoplastic polyester with controlled branching or even with linear structures comprising of branching agents in its backbone, the process comprising a preparation of condensation product of at least one trifunctional carboxylic acid or anhydride thereof with at least one mono alkyl alcohol at temperature 255-265ºC and under pressure 1.5- 1.8 kg/cm2 and reacting the same with diols such as monoethylene glycol, 1,3 propane diol, 1,6 hexane diol or 1,4 butane diol to form an adduct. The polymer is further polymerized by solid state polymerization in nitrogen atmosphere at 190-210ºC to obtain chips of high molecular weight and are extruded and melt spun into filament or fiber or extruded into films and post process curable articles. The polyester formed resulted in increased rate of Solid state polymerization and reduced rate of polymer crystallizability.

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, 2005 PROVISIONAL SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION CONTROLLED BRANCHED POLYESTER AND PROCESS FOR MAKING THE SAME APPLICANTS Name : Reliance Industries Limited Address : Reliance Technology Center, B-4 MIDC Industrial Area, Patalganga 410220, Dist Raigad, Maharashtra, India Nationality: Indian company incorporated under the Companies Act 1956 INVENTORS Name : Nadkarni Vikas Madhusudan Address : A18 Garden Estate, Off DP Road, Aundh,Pune -411007, Maharashtra, India Nationality: Indian Name: Venkatachalam Subbiah Address : B3, First floor, Flat no 3 , SHIVPARVATI Co-op Housing Society, Plot no 106-110, Sector 21, Nerul (East) Navi Mumbai, 400706 Maharashtra India Nationality: Indian Name : Honkhambe Pandurang Nagnath Address: A/P: Bhatambare Ta. Barshi; Dist. Solapur-413401 Maharashtra India Nationality: Indian Name : Deshpande Amit Avinash Address: 203,Kanuma Apartments Hendrepada Kulgaon Badlapur(W)-421503 Maharashtra, India Nationality: Indian 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 THE INVENTION The present invention relates to polyester with controlled branching having composition comprising at least one carboxylic acid or anhydride or ester thereof, at least one diol or polyol and at least one branching agent; said branching agent comprises at least one tri-functional carboxylic acid or anhydride thereof, at least one mono alkyl alcohol and at least one diol which is uniformly distributed in the polymer backbone. The present invention also relates to a process of making the above polyester with controlled and uniformly distributed branching in the polymer backbone. The present invention also relates to use of the above polyester in manufacturing low pill fiber or filament, molded articles with high impact resistance and transparent films. BACKGROUND OF THE INVENTION Thermoplastic polyesters are widely used in manufacturing of fibers or filaments or films or container by extrusion, molding (injection or stretch blow). However, the polyester is known for deficiencies in melt rheology. In particular, polyester has typically low melt viscosity, low melt strength and low melt elasticity. Such limitations have left the polyester with narrow processing window and always required specialized equipments for processing. Generally melt viscosity and melt strength of polyester can be improved by introducing branching in the linear chain structure of the polyester and /or increasing molecular weight through chain extension. One approach of introducing branching in polyester is by adding branching agent such as poly-functional carboxylic acids or anhydrides or alcohols directly during the polymerization reaction or melt mixing process. Depending upon the type of branching agent used to modify polyester, the overall effect of the reaction-melt mixing may in fact decrease the molecular weight of the polyester. This will often be the case where the only type of branching agent used is a polyol branching agent. Most widely used branching 2 agents are tri-functional monomer such as trimelletic anhydride, 1,3,5- Benzenetricarboxylic acid, 1,1,1-Tris(hydroxymethyl)ethane, 1,1,1- Tris(hydroxymethyl)propane and " tetra-functional monomer such as pentaerythritol for polyester. Regardless of the type of branching agent used to effectively modify the polyester, it is important that the degree of branching can be controlled during the reaction and that the branching occurs uniformly in the polyester. The most simple way in which the agent can be added to the polyester is by direct addition. However, this mode of addition has been found to lead to gel formation through excessive localized chain coupling and non uniform branching within the modified polyester. This also leads to detrimental discolouration. Furthermore, it is not uncommon to use amount of less than 1000 ppm weight percent of the branching agent, relative to the polyester to be modified. At these low levels, it is difficult to provide a uniform distribution of the branching agent in the polyester by direct addition which leads to non-uniform branching in polyester. The above branching agents, being multifunctional, are active and if used directly in the polymerization reaction, it may be difficult to control the chain length and distribution of branching, which ultimately affects melt viscosity. Thus non-uniform branching makes the polyester product inconsistent in quality including inconsistent polyester rheology which leads to spinning problems as well as abnormalities in down stream processing. We have not come across any existing reference of the polyester with controlled branching having composition comprising at least one carboxylic acid or anhydride or ester thereof, at least one diol or polyol and at least one branching agent; said branching agent comprises at least one tri-functional carboxylic acid or anhydride thereof, at least one mono alkyl alcohol and at least one diol which is uniformly distributed in the polymer backbone as per the invention. OBJECTS OF THE INVENTION: An object of the invention is to provide polyester with controlled branching having composition comprising at least one carboxylic acid or anhydride or ester thereof, at least one diol or polyol and at least one branching agent; said branching agent 3 comprises at least one tri-functional carboxylic acid or anhydride thereof, at least one mono alkyl alcohol and at least one diol which is uniformly distributed in the polymer backbone. Another object of the invention is to provide polyester with controlled branching; said product is cost effective as there is no occurrence of gelling. Another object of the invention is to provide polyester with controlled branching; said product is consistent in quality as the branching occurred uniformly in the polymer chain and controlled chain length. Another object of the invention is to provide a process for making the above polyester with controlled branching; said process is cost-effective as there is no occurrence of gelling. Another object of the invention is to provide a process for making the above polyester with controlled branching; said process gives product with controlled branching and uniformly distributed in the polymer backbone. Another object of the invention is to provide the use of the above polyester in manufacturing low pill fiber or filament, molded articles with high impact resistance, higher melt strength for blown film extrusion and extrusion blow molding and transparent films. DETAILED DESCRIPTION According to the invention, there is provided polyester with controlled branching having composition comprising at least one carboxylic acid or anhydride or ester thereof, at least one diol or polyol and at least one branching agent; said branching agent comprises at least one tri-functional carboxylic acid or anhydride thereof, at least one mono alkyl alcohol and at least one diol which is uniformly distributed in the polymer backbone. 4 According to the invention, there is provided a process for making the above polyester with controlled branching, the process comprises: a esterifying at least one carboxylic acid, anhydride or ester thereof and at least one diol or polyol at temperature in the range of 255 to 265° C under pressure in the range of 1.5 to 1.8 Kg/cm2, b adding at least one branching agent which comprises at least one tri-functional carboxylic acid or anhydride thereof, at least one mono alkyl alcohol and at least one diol at the end of the esterification reaction followed by agitating the reaction mixture for at least 10 min; and c polycondensing the reaction mixture at temperature in the range of 260 to 290° C under pressure in the range of 0.5 to 1mm Hg and draining the polyester. The dicarboxylic acid is selected from terephthalic acid, adipic acid, glutaric acid, naphthalene dicarboxylic acid, perylene dicarboxylic acid. The diol or polyol is selected from ethylene glycol, butanediol, 1,3-propane diol, 1,6-hexane diol. The mole ratio of hydroxyl group to carboxyl group is in the range of 1.2 to 2. The reaction temperature also affects the reaction rate of poly-condensation. It is preferred to carry out the poly-condensation reaction at temperature in the range of 260-285°C. The above process is either a batch process or a continuous process. In the batch process the branching agent is added followed by agitation for at least 10 minutes while in the continuous process, the molten adduct is added by a transfer line injection followed by mixing for at least 10 minutes. The tri-functional carboxylic acid or anhydride thereof used in the branching agent is selected from 1,3,5-Benzene-tri-carboxylic acid, 1,2,3-Benzene-tri-carboxylic acid or anhydride thereof, 1,2,4-Benzene-tri-carboxylic acid (Trimelletic acid) or anhydride thereof, 2,3,6-naphthalene tri-carboxylic acid or anhydride thereof, perylene tri-carboxylic acid or anhydride thereof. The mono alkyl alcohol used in the branching agent is a long chain alcohol having carbon chain length of C1 to C25 or highly substituted branched aliphatic or aromatic alcohol. Preferably, the long chain mono alkyl alcohol is selected from butanol, 5 hexanol, heptanol, octanol, nonanol or dodecanol. Preferably highly substituted branched aliphatic or aromatic alcohol is selected from isobutanol, isooctyl alcohol, isododecyl alcohol, neopentyl alcohol or benzyl alcohol. The diol used in the branching agent is selected from monoethylene glycol, 1,3-propane diol, butane diol or 1, 6 Hexane diol. The ratio of trifunctional carboxylic acid or anhydride thereof, mono alkyl alcohol and diol is in the range of 1:0.5:2 to 1:1.5:7. The branching agent is added in the range of 0.1 to 10 % by wt in the polyester, preferably between 0.4-2 % by weight of the polyester. In one of the embodiment of the invention, the above polyester is used in the manufacture of low pill fiber or filament. In another embodiment of the invention, the above polyester is used in the manufacture of molded articles with high impact resistance. In yet another embodiment of the invention, the above polyester is used in the manufacture of transparent films. Thus the present invention allows the change in the composition of matter of polyester in terms of extent and length of branching to suit the polyester for end application requiring specific attributes like low pill, high impact or transparency. Incorporation of the above branching agent into the polyester backbone increased the free volume due to the disturbance in the dense chain packing of the polyester by the pendent alkyl units, which, in turn, facilitated properties, such as, improved impact resistance and transparency in molded articles, higher melt strength for blown film extrusion and extrusion blow molding, improved pilling resistance in fibers and filaments, etc. Polyester of the invention has crystallization temperature in the range of 180-219° C and poly-dispersity in the range of 2.35 to 3.64. Die swell of the polymer increased with increase in the concentration of branching agent. This suggests the increased chain entanglement with increased branching and decrease in crystallization rate which is seen from the drop in crystallization temperature from DSC data. According to 6 the die swell data, the polyester has uniform branching in the polymer chain and the branching length is controlled by controlling chain length of the alkyl group of the branching agent. There is no occurrence of gelling in the polymerization as well as in the product. Thus the product and process are cost-effective. The process also results in product with consistent quality. Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. Example 1 1,4- bis(2-hydroxy ethyl) 2-octyl tribenzoate Trimelletic anhydride (424 g, 2.2 mol) and 1-octanol (287g, 2.2 mol) was heated at 200°C under nitrogen pressure of 25 psi with stirring. The reaction was carried out for 4 hours. The reaction mixture was cooled and further depressurized. To this reaction mixture, monoethylene glycol (MEG) (548 g 8.8 mol) was added. The reaction was further carried out at temperature of 220°C under the nitrogen pressure of 25 psi. for 4 hours. The reactor was depressurized and product was drained under hot condition. The product was characterized by NMR and saponification value. 1H-NMR (CDCI3, ppm): 8.5 (d, 1H), 8.2 (dd, 1H), 7.7 (d, 1H), 4.7 (m, 2H), 4.4 (m, 2H), 4.3 (m, 2H), 3.9 (m, 4H), 1.8 (m, 2H), 1.3 (m, 10H), 0.95 (t, 3H). Sap.Value = 410 meq KOH/g Example 2 Control polyester without branching agent Monoethylene glycol MEG (6 kg) and purified terephthalic acid (PTA) (8 kg) (1:2 molar ratio) was esterified in the presence of Sb2O3 (2. 8 g) as a catalyst at 260°C under nitrogen pressure of 1.5 - 1.85 kg / cm2. Polycondensing the esterified mixture at 285°C under reduced pressure of 1-5 mm Hg. After a 7 certain rise in torque, vacuum was broken and the reactor was pressurized with nitrogen. The polymer was drained as strands by quenching in a water bath. The strands are then cut into chips in a pelletizer. The polyester was analysed by GPC, DSC and Rheology and used as control polyester. Example 3 Polyester with branching agent prepared according to Example 1 Monoethylene glycol MEG (6 kg) and purified terephthalic acid (PTA) (8 kg) (1:2 molar ratio) was esterified in the presence of Sb2O3 (2. 8 g) as a catalyst at 260°C under nitrogen pressure of 1.5 - 1.85 kg / cm2. The branching agent prepared according to the example 1 was added at the end of esterification at 260 °C and the resultant reaction mixture was further agitated for 30 minutes. The esterified mixture was polycondensed at 285°C under reduced pressure of 1-5 mm Hg. After a certain rise in torque, vacuum was broken and the reactor was pressurized with nitrogen. The polymer was drained as strands by quenching in a water bath. The strands are then cut into chips in a pelletizer. The presence of branching in copolyester was confirmed by GPC, DSC and Rheology. The occurrence of branching is often accompanied by broadening of the molecular weight distribution. Polydispersity data was found to be in the range 3.0 to 3.6, which indicates the broadening of molecular weight distribution due the branching (Table 1). Figure 1 illustrates Die swell ratio (referred as 1) data at various shear rates [referred as 2 (Sec-1)] measured at barrel temperature of 275°C using Capillary Rheometer (Die diameter = 1 mm and Die Length = 10 mm) for control sample (ie without additive), polyester comprising 1% branching agent and polyester comprising 1.5 % branching agent are given in 3,4 and 5 respectively. Die swell of the polyester increased with increased concentration of 8 branching agent (Figure 1), this suggests the increased chain entanglement with increased branching. The increased branching should always result in decrease in crystallization rate which is seen from results of DSC in Table 2 ie. the drop in crystallization temperature. Table 1: Polydispersity data from GPC analysis: Resin Polydispersity Control 2.35 1 mole% adduct 3.08 1.5 mole% adduct 3.64 Table 2: Crystallization temperature data from DSC analysis Resin Crystallization temperature (°C) Control 219 1 mole% adduct 208 1.5 mole% adduct 197 Dated this the 23rd day of February 2007

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396-MUM-2007-CORRESPONDENCE(11-6-2012).pdf

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396-MUM-2007-CORRESPONDENCE(28-08-2008).pdf

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