FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
"AN ISOSORBIDE CONTAINING POLYESTER POLYMER AND PROCESS FOR PREPARATION THEREOF"
We, Reliance Industries Limited, of 3rd Floor, Maker Chamber-VI, 222, Nariman Point, Mumbai - 400021, Maharashtra, India.
The following specification particularly describes the nature of the invention and the manner in which it is performed:

AN ISOSORBIDE CONTAINING POLYESTER POLYMER AND PROCESS FOR PREPARATION THEREOF
FIELD OF THE INVENTION
The present invention is a patent of addition of Indian Patent Application No. 702/MUM/20I0. The present invention is a modification of the process for preparing polyester polymer using a catalyst system comprising antimony compound and inorganic tin compound. The present invention relates to an isosorbide containing polyester polymer wherein isosorbide is incorporated as a comonomer and process for its preparation using said catalyst system. The invention also relates to a process which results in improved colour and improved polymerization rate (melt/ solid-state).
BACKGROUND OF THE INVENTION
Polyesters such as polyethylene terephthalate (PET) are used in large quantities in the manufacture of textile fibers, packaging films and containers. Typically, such polyesters are synthesized by a catalyzed two-stage reaction. In the first stage, esterification reaction (-260°C) is carried out between a dicarboxylic acid and a polyol. The esterification reaction is followed by melt polymerization wherein the ester formed in the first stage undergoes polycondensation (-290°C) resulting in polyester. Often the polyester obtained after melt polymerization is further subjected to solid-state polymerization.
The diol l,4,3,6-dianhydro-D-Sorbitol,referred herein as isosorbide,is readily made from renewable resources, such as sugar and starches. For example,isosorbide can be made from D-Glucose by hydrogenation, followed by acid catalyzed reaction.
Copolymers containing isosorbide, ethylene glycol and terephthaloyl moieties are known in the art. German Patent Application No. 1,263,981 discloses a copolymer containing isosorbide, ethylene glycol, and terephthaloyl moieties, with the molar ratio of ethylene glycol to isosorbide of about 90:10. The polymer is used as a minor (about 10%) component of a blend with polypropylene to improve the dyeability of polypropylene fiber. The polymer was made by melt polymerization of dimethyl terephthalate, ethylene glycol, and isosorbide and the process of preparation been described in general terms.
U.S. Patent No. 5,959,066 (Charbonneau et ah) discloses polyesters that include isosorbide as a co-monomer and methods for making them. This patent discloses process

steps to obtain isosorbide-containing polymers from esterification to solid-state polymerization. No mention is made concerning the need to obtain polymer with low color..
U.S. Patent No. 6,063,464 (Charbonneau e( al) describes isosorbide-containing polyesters and methods for making same. The patent claims the composition of isosorbide containing polyesters and a process for their solid-state polymerization. The possible applications include beverage bottle, film or sheet, fibers, optical materials, and compact disc or digital versatile disc. The patent does not make mention of any process conditions aimed at the minimization of color.
U.S. Patent No. 5,958,581 (Khanarian et al.) describes polyester film ano>methods for making the same. Film comprised of isosorbide-containing polyester is claimed. Several compositions are claimed. No mention is made concerning color.
Indian Patent Application No. 702/MUM/2010 discloses a catalyst system for preparing polyester resin comprising of an antimony compound and an inorganic tin compound, wherein said catalyst reduces the polymerization time at all stages of polyester synthesis including esterification, polycondensation and solid state polymerization, and reduces the generation of degradation product, and improves the L colour of the polyester resin, wherein said inorganic tin compound is present in the range of about 5 to 300 ppm as a metallic tin by weight of polyester and said antimony compound is present in an amount of 100 to 400 ppm of elemental antimony. It also discloses a process for the preparation of polyester resin which comprises esterifying at least one dicarboxylic acid or mono-esters thereof or di-ester thereof and at least one diol or polyol characterised in that said esterification is carried out in the presence of said catalyst system.
The present invention demonstrates that when a polyester containing isosorbide as comonomer was prepared using a catalyst system comprising antimony compound and inorganic tin compound, it resulted in an isosorbide containing polyester polymer with better properties compared to isosorbide containing polyester prepared by conventional methods. The isosorbide containing polyester prepared by the process of the present invention demonstrated improved colour and the polymerization rate (melt / solid state) was also improved.
OBJECTS OF THE INVENTION
It is an important object of the present invention to provide improved isosorbide containing polyester polymer having improved color properties.

It is another object of the present invention to prepare polyester with High Tg without negatively affecting the color properties of the polyester.
It is still another important object of the present invention to provide an improved process for preparing isosorbide containing polyester using a catalyst system comprising antimony compound and inorganic tin compound, wherein isosorbide is incorporated as a comonomer in the backbone of the polyester.
It is a further object of the present invention to provide a process for preparing
isosorbide containing polyester with improved color using said catalyst system.
Another object of the present invention is to provide a process for preparing
isosorbide containing polyester which results in improvement of polymerization rate (melt /
solid-state).
Still another object of the present invention is to provide an isosorbide containing polyester resin with improved properties for end-use applications.
Yet another object of the present invention is to provide a process for preparing isosorbide containing polyester for hot fill applications above 90°C.
SUMMARY OF THE INVENTION
The above and other objects of the present invention are achieved by preparing isosorbide containing polyester wherein isosorbide is incorporated as a comonomer in the backbone of the polyester using a catalyst system comprising antimony cofnpound and inorganic tin compounds as co-catalysts.
The present invention provides an improved isosorbide containing polyester polymer
composition comprising: (a) one or more dicarboxylic acids; (b) two or more diols, with at
least one diol being mono-ethylene glycol (MEG) and one diol being isosorbide incorporated
as a comonomer in the backbone of the polyester; (c) a tin based catalyst residue; (d) a
antimony based catalyst residue; wherein the amounts of total dicarboxylic acids and total
diols is at least 70 to 90 wt% and 30 to 90 wt% of the total composition, respectively; and the
amount of tin is in the range of 5 to 300 ppm as elemental tin by weight of the total
composition and the amount of antimony is in the range of 100 to 400 ppm as elemental
antimony by weight of the total composition; and wherein the amount of isosorbide is in the
range of 1 to 50 wt% of the total composition.
The present invention discloses a process for preparing isosorbide containing polyester resin wherein isosorbide is added as 1,4, 3, 6-dianhydro-D-SorbitoI.

The said isosorbide containing compound is added in the range of 1 to 50 wt% of the polyester polymer, preferably 1 to 20 wt% of the polyester polymer. The amount of isosorbide is from 1 to 80 wt% of the total MEG.
The said dicarboxylic acid is selected from the group consisting of terephthaltc acid, isophthalic acid, adipic acid, glutaric acid and sebacic acid and said diol is selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, 1,3 -propane diol and neopentyl glycol, preferably mono-ethylene glycol and isosorbide.
The said catalyst system comprises of an antimony compound and an inorganic tin compound, wherein said catalyst reduces the polymerization time at all stages of polyester synthesis including esterification, melt polymerization and solid state polymerization, and results in improved color of the polymer.
The said catalyst system comprises inorganic tin compound added in the range of about 5 to 300 ppm as elemental tin by weight of polyester polymer and said antimony compound is present in an amount of 100 to 400 ppm as elemental antimony by weight of polyester polymer.
In a preferred embodiment, the inorganic tin compound is selected from group consisting of tin oxalates, tin chlorides, tin fluorides, tin sulphate or mixtures thereof and is present in an amount of 5 to 50 ppm as elemental tin by weight of polyester polymer.
Preferably, the inorganic tin compound is added as a liquid or slurry in mono-ethylene glycol (MEG) at any the stages of esterification or melt polymerization such as in slurry mixing tank, slurry feed tank or oligomer line.
In accordance with the present invention the catalyst system have tin compound and antimony compound which act synergistically evincing unexpected and improved properties in terms of color and reactivity. In addition, it is very easy to handle because slurry with higher concentration up to 15% can be prepared in a ball mill at normal room temperature without any nitrogen blanketing. Slurry is fairly stable at room temperature and can be added at any stage during polymerization process. Also the inorganic tin compound has melting point of 280°C and it decomposes at >400°C. The polymerization process temperatures are in the range of 250-300°C. At that temperature the inorganic tin compound gets melted and distributed uniformly in the polymer matrix resulting in improved properties of the polyester.
In various embodiments, the antimony compound is selected from one or more of . antimony trioxide, antimony tetraoxides or antimony pentoxides, antimony carboxylates such as antimony triacetate, antimony tristearate, antimony halide such as antimony trichloride or antimony trifluride. The preferred Antimony compounds are Antimony trioxide and

antimony triacetate.
Preferably, said antimony compound is present in the range of 280-290 ppm as elemental antimony based on total weight of polyester polymer.
Preferably, sai,d inorganic tin compound is present within the range of 10-50 ppm as elemental tin based on total weight of polyester, more preferably 40 ppm.
Optionally, Phosphrous and Cobalt may be added as a thermal stabilizers and colorant, respectively, to the prepolymer. The quantity of these theremal stabilizers and colorants may be 25 ppm.
The present invention discloses a process for the preparation of isosorbide containing
polyester polymer in presence of antimony and inorganic tin compound catalyst system
comprising of steps of:
(a) esterifying one or more dicarboxylic acid with one or more diol at a temperature in
the range of 250°C to 290°C to obtain an esterified mixture, wherein at least one
dicarboxylic acid is an aromatic dicarboxylic acid and at least one diol is mono-ethylene glycol (MEG);
(b) melt polymerizing the esterified mixture at temperature in the range of 260°C to 300°C to obtain polyester polymer having Inherent Viscosity (IV) of 0.3 to 0.6 dl/g;
(c) incorporating at least one inorganic tin compound either before or during or after any of method steps (a) or (b);
(d) incorporating at least one antimony compound either before or during or after any of method steps (a) or (b);
(e) incorporating isosorbide as a comonomer either before or during or after any of method steps (a) or (b).
In another embodiment of the present invention, a process for the preparation of polyester resin using a catalyst system comprising of antimony and inorganic tin compound is disclosed wherein the polyester polymer is solid state polymerized to obtain a high molecular weight polyester resin having IV of 0.7 dl/g to 1.2 dl/g.
Preferably, a process for the preparation of polyester resin is disclosed wherein said inorganic tin compound forms stable slurry.
Preferably, said slurry can be and is prepared at high concentration up to 15%.
Preferably, said slurry can be prepared at room temperature without nitrogen blanketing.
Preferably, said slurry is stable at room temperature and may be added at,any stage of polymerization process.


Preferably, a process for the preparation of polyester resin is disclosed wherein said inorganic tin compound is uniformly distributed in the polymer matrix.
Preferably, said polyester has improved colour and improved properties for end-use applications.
In yet another embodiment, the present invention provides a process for preparing isosorbide containing polyester resin with improved color using said catalyst system wherein said catalyst reduces the polymerization time at all stages of polyester synthesis and improves resin color with increase in glass transition temperature. This resin can be used for hot fill packaging applications.
DETAILED DESCRIPTION OF THE INVENTION
The present invention discloses a process for preparing isosorbide containing polyester using a catalyst system comprising antimony compound and inorganic tin compounds as cocatalyst. Isosorbide is incorporated as a comonomer in the backbone of the polyester. The process claimed improves color of the isosorbide containing polyester resin. The said process also reduces the polymerization time and thus enhances the productivity. Use of such catalyst reduces polymerization time at all stages of polyester synthesis i.e., esterification, melt polymerization and solid state polymerization. A further object of the present invention is to provide a catalyst system that reduces the generation of degradation products thereby improving polymer quality and reduces degradation products like acetaldehyde.
The present invention discloses that the catalyst composition of the present invention comprising inorganic tin compound is synergistic in nature evincing unexpected and improved properties. In addition it is very easy to handle because slurry with higher concentration up to 15% can be prepared in a ball mill at normal room temperature without any nitrogen blanketing. Slurry is fairly stable at room temperature and can be added at any stage during polymerization process. Also the Inorganic tin compound has melting point of 280°C and it decomposes at > 400°C. The polymerization process temperatures are in the range of 250-300°C. At that temperature the inorganic tin compound gets melted and distributed uniformly in the polymer matrix resulting in improved properties. In a most preferred embodiment, catalyst system comprises of antimony trioxide in the range of 280-290 ppm and inorganic tin in the range of 20-40 ppm, preferably 40 ppm based on the weight of polymer.

Optionally, 25 ppm Phosphrous and 25 ppm of Cobalt were added as a thermal stabilizer and colorant to the prepolymer.
The present invention is illustrated and supported by the following examples. These are merely representative examples and optimization details and are not intended to restrict the scope of the present invention in any manner.
EXAMPLES
Melt Polymerization: Comparative
Purified terephthalic acid was esterified with MEG in 1:2 ratio along with 1.8wt % Isophthalic acid. The oligomer obtained was further, melt polymerized at 290°C to obtain amorphous polyester prepolymer having IV up to 0.6 dl/g. Antimony trioxide (290ppm as elemental antimony) was added as a catalyst, 25 ppm P and 25 ppm of Cobalt was added as a thermal stabilizer and colorant to the prepolymer. The low IV prepolymer melt was then extruded out from the reactor in the form of amorphous cylindrical chips. This prepolymer was considered as "Control", These amorphous chips were analyzed for IV, Color and COOH content and DSC analysis. These amorphous prepolymer particles were used as precursor for solid-state polymerization.
Example 1:
Purified terephthalic acid was esterified with monoethylene glycol (MEG) in 1:2 ratio
along with 5 wt % Isosorbide at 260°C. The oligomer obtained was further melt polymerized
*
at 290°C to obtain polyester prepolymer having IV up to 0.6 dl/g. Antimony trioxide ( 290ppm as elemental antimony) was added as a catalyst and 25 ppm P and 25 ppm of Cobalt was added as a thermal stabilizer and colorant to the prepolymer. The low IV prepolymer melt was then extruded out from the reactor in the form of amorphous cylindrical chips. These amorphous chips were analyzed for IV,Color and COOH content. These amorphous prepolymer particles were used as precursor for solid-state polymerization
Example 2:
Purified terephthalic acid was esterified with monoethylene glycol (MEG) in 1:2 ratio along with 5 wt % Isosorbide. Tin oxalate (40 ppm as a metallic tin) in the form of slurry at 260°C was added as catalyst. The oligomer obtained was further melt polymerized at 290°C

to obtain polyester prepolymer having IV up to 0.6 dl/g. Antimony trioxide ( 290ppm as elemental antimony) was added as catalyst and 25 ppm P and 25 ppm of Cobalt was added as a thermal stabilizer and colorant to the prepolymer. The low IV prepolymer melt was then extruded out from the reactor in the form of amorphous cylindrical chips. These amorphous chips were analyzed for IV, Color and COOH content. These amorphous prepolymer particles were used as precursor for solid-state polymerization.
Example 3:
Same example as example 2 with 8 wt% isosorbide and 60 ppm tin oxalate can be included here just to cover other values in the range.
Melt Polymerization Comparison:-

ID Sb
(ppm) Sn (ppm) Co
(ppm) P
(ppm) IPA Isosorbide (%) Ester ification Time (Min) Poly condensation Time (Min)
C 290 0 25 25 1.8 0 197 97
El 290 0 25 25. 0 5 237 108
E2 290 40 25 25 0 5 202 99
Amorphous chips Comparison:

: ID IV(dI/g) L* a* b*
C 0.622 70.0 0.57 -1.79
El 0.586 66.7 -1.18 4.3
E2 0.590 67,3 0.52 2.21
Thermal Behavior

Recipe Tg(°C)
C 74.5
El 81.8
E2 83.8

Solid State Polymerization: -
Amorphous prepolymer particles having IV of 0.6 dl/g obtained according to the'examples C, El, E2 were solid-state polymerized at 212°C (Gas Temperature) under Nitrogen atmosphere to raise the IV up to 0.8 dl/g.

ID rv(dl/g) L* a * b*
C 0.748 87.8 -0.208 1.3
El 0.778- 79.3 -0.85. 5.1
E2 0.803 80.2 0.29 2.8
Advantages of the present invention:
1. Isosorbide containing polyester resin made as per the present invention has improved glass transition temp. The polymerization time is reduced significantly at all stages and polymer quality is improved significantly in terms of color.
2. This modified polyester resin with improved glass transition temperature is more suitable for moulding and blow moulding hot fill bottles and containers where high hot filling (>90°C) required for improved shelf life of the content inside.

We claim:
1. A polyester composition comprising:
(a) at least a first dicarboxylic acid wherein said first dicarboxylic acid is an
aromatic dicarboxylic acid
(b) at least two diols wherein the said two diols being mono-ethylene glycol (MEG) and isosorbide wherein the amount of isosorbide is in the range of 1 to 50 wt% of the total composition;
(c) at least one tin based catalyst wherein the amount of tin is in the range of 5 to 300 ppm as elemental tin by weight of the total composition; and
(d) at least one antimony based catalyst wherein the amount of antimony is in the range of 100 to 400 ppm as elemental antimony by weight of the total composition.
2. The polyester composition as claimed in claim 1, wherein said first dicarboxylic is
terephthalic acid (TPA).
3. The polyester composition as claimed in claim 1 further comprising a second dicarboxylic acid.
4. The polyester composition as claimed in claim 3 wherein said second dicarboxylic acid is selected from the group consisting of isophthalic acid, adipic acid, glutaric acid, sebacic acid and combination thereof.
5. The polyester composition as claimed in claim 1 further comprising a diol selected from the group consisting of diethylene glycol, triethylene glycol, propylene glycol, butanediol, 1,3 -propane diol ,neopentyl glycol and combination thereof,
6. The polyester composition as claimed in claim 1, wherein said tin based catalyst is in at least one form selected from the group comprising of elemental, oxide and salts.
7. The polyester composition as claimed in claim 6 wherein said tin based catalyst is selected from group consisting of tin oxalate, tin chloride, tin fluoride, tin sulphate or mixtures thereof.

. 8. The polyester composition as claimed in claims 1 or 6 wherein said tin based catalyst is preferably present in the range of 5-50 ppm, more preferably 40 ppm based on the weight of the total composition.
9. The polyester composition as claimed in claim 1, wherein said antimony based catalyst is in at least one form selected from the group comprising of elemental, oxide and salts.
10. The polyester composition as claimed in claim 9 wherein said antimony based catalyst is selected from group consisting of antimony trioxide, antimony tetraoxide, antimony pentoxide, antimony carboxylates, antimony halide, or mixtures thereof.
11. The polyester composition as claimed in claims 1 or 10 wherein said antimony based catalyst is preferably present in the range of 280-290 ppm based on weight of the total composition.
12. A process for preparation of a polyester composition comprising the steps of:

(a) esteritying at least a first dicarboxylic acid with at least a first diol at a temperature in the range of 250°C to 290°C to obtain an esterified mixture, wherein the first dicarboxylic acid is an aromatic dicarboxylic acid and the first diol is mono-ethylene glycol (MEG);
(b) melt polymerizing said esterified mixture at temperature in the range of 260°C to 300°C to obtain the polyester having Inherent Viscosity (IV) of 0.3 to 0.6 dl/g;
(c) incorporating at least one tin based catalyst either before or during any of the process steps (a) or (b);
(d) incorporating at least one antimony based catalyst either before or during any of
the process steps (a) or (b);

(e) incorporating a second diol either before or during any of the process steps (a) or
(b), wherein the second diol is isosorbide.
13. The process for the preparation of the polyester composition as claimed in claim 12,
wherein the polyester is solid state polymerized to obtain a high molecular weight
polyester resin having IV of 0.7 dl/gto 1.2 dl/g.

14. The process for the preparation of the polyester composition as claimed in any of claims 12 to 13, wherein isosorbide is added in the range of 1 to 50 wt% of total composition, preferably 1% to 20% of the weight of the total composition.
15. The process for the preparation of the polyester composition as claimed in any of claims 12 to 14, wherein the first di-carboxylic acid is preferably terephthalic acid (TPA).
16. The process for the preparation of the polyester composition as claimed in any of claims 12 to 15, comprising a second di-carboxylic acid selected from the group consisting of isophthalic acid, adipic acid, glutaric acid,sebacic acid and mixture thereof
17. The process for the preparation of the polyester composition as claimed in any of claims 12 to 16 comprising a third diol selected from the group consisting of diethylene glycol, triethylene glycol, propylene glycol, butanediol, 1,3 -propane diol meopentyl glycol and mixture thereof,
IS. The process for the preparation of the polyester composition as claimed in claim 12 wherein the tin based catalyst is present in at least one form selected from the group comprising of elemental, oxide and salts.
19. The process for the preparation of the polyester composition as claimed in claim 18 wherein the tin based catalyst is selected from group consisting of tin oxalate, tin chloride, tin fluoride, tin sulphate or mixtures thereof.
20. The process for the preparation of the polyester composition as claimed in any of the claims 12 to 19 wherein the tin based catalyst is present in the range of 5-50 ppm, preferably 40 ppm based on the weight of the total composition.
21. The process for the preparation of the polyester composition as claimed in claim 12, wherein the antimony based catalyst is present in at least one form selected from the group consisting of elemental, oxide and salts.

22. The process for the preparation of the polyester composition as claimed in claim 21 wherein the antimony based catalyst is selected from group consisting of antimony trioxide, antimony tetraoxide, antimony pentoxide, antimony carboxylates, antimony halide, or mixtures thereof.
23. The process for the preparation of the polyester composition as claimed m any of the claims 12 to 22 wherein the antimony based catalyst is preferably present in the range of 280-290 ppm based on weight of the total composition.
24. The process for the preparation of the polyester composition as claimed in any of the claims 12 to 23, wherein the tin based catalyst is added as slurry in mono-ethylene glycol.
25. The process for the preparation of the polyester composition as claimed in claim 24 wherein said slurry is prepared at high concentration up to 15% in a ball mill at normal room temperature without any nitrogen blanketing.