CLIAMS:We Claim:

1. A process for preparing a polymer composition having bacteriostatic properties, the process comprising mixing 0.1 to 8% by weight of Neem oil with 92 to 99.9% by weight of thermoplastic polymer.

2. The process as claimed in claim 1, wherein the polymer is selected from the group comprising polyester, polyolefin and a combination thereof.

3. The process as claimed in claim 2, wherein the polyester is polyethylene terephthalate.

4. The process as claimed in claim 2, wherein the polyolefin is selected from the group comprising High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene, Ethylene vinyl acetate, and combinations thereof.

5. The process as claimed in claim 1, wherein 0.1 to 5% by weight of Neem oil is mixed with 95 to 99.9% by weight of thermoplastic polymer.

6. A polymer composition having bacteriostatic properties, the composition comprising 92 to 99.9% by weight of thermoplastic polymer and 0.1 to 8% by weight of Neem oil.

7. The composition as claimed in claim 6, wherein the thermoplastic polymer is selected from the group comprising polyester, polyolefin or a combination thereof.

8. The composition as claimed in claim 7, wherein the polyester is polyethylene terephthalate.

9. The composition as claimed in claim 7, wherein the polyolefin is selected from the group comprising High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene, Ethylene vinyl acetate, and combinations thereof.

10. The composition as claimed in claim 6, wherein the composition comprises 0.1 to 5% by weight of Neem oil.
,TagSPECI:
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
A process for preparing a polymer composition having bacteriostatic properties

APPLICANTS
Reliance Industries Limited, 3rd Floor, Maker Chamber IV, 222, Nariman Point, Mumbai - 400 021, Maharashtra India, an Indian Company

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes this invention and the manner in which it is to be performed:
 
FIELD OF THE INVENTION
This invention relates to a process for preparing a polymer composition having bacteriostatic properties and to the composition prepared by the said process.

BACKGROUND OF THE INVENTION
Azadirachta indica, also known as Neem, Nimtree, and Indian Lilac is a tree whose oil is known to have microbicidal/antimicrobial/bacteriostatic and insect repellent properties. Neem oil is often used in the preparation of fabrics to impart such microbicidal and/or insect repellent properties to the fabrics. Ordinarily, the processes used to prepare such fabrics include surface treatment of the fabrics with Neem oil or impregnation of the Neem oil into the fabrics using cross-linking agents like glyoxal or glycol resin or fixing microcapsules of Neem oil onto the fabric surface. All such processes generally require the use of an additional binding agent to facilitate the binding of the Neem oil to the fabric surface. In this manner, the pre-fabricated textile material is treated with the Neem oil to impart the microbicidal and insect repellent properties of Neem oil to the textile. However, such processes usually result in non-uniform distribution of the Neem oil on the surface of the fabric, or the Neem oil gets washed off from the surface of the fabric within the first few washes, thus resulting in only short-term microbicidal and/or insect repellent properties of the fabric.

There is a need for a process for preparing polyesters or polyolefins which have bacteriostatic properties uniformly distributed throughout the polyester or polyolefin, where the woven fabrics prepared from such polyesters or polyolefins do not cause any skin irritation or allergies, where the bacteriostatic properties do not get washed off easily and provide long-lasting desirable properties to the fabric.

SUMMARY OF THE INVENTION
According to an embodiment of the invention, there is provided a process for preparing a polymer composition having bacteriostatic properties, the process comprising mixing 0.1 to 8% by weight of Neem oil with 92 to 99.9% by weight of thermoplastic polymer.

According to yet another embodiment of the invention, there is provided a polymer composition having bacteriostatic properties, the composition comprising 92 to 99.9% by weight of thermoplastic polymer and 0.1 to 8% by weight of Neem oil.

It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For simplicity and illustrative purposes, the present invention is described by referring mainly to exemplary embodiments thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one of ordinary skill in the art that the present invention may be practiced without limitation to these specific details. In other instances, well known methods have not been described in detail so as not to unnecessarily obscure the present invention.

In the context of the invention, the term “Neem oil” as used in the specification refers to oil pressed from the fruit and seeds of the Neem tree, which oil comprises at least 300 ppm of azadirachtin, at least 4000 ppm of nimbin, and at least 5000 ppm of salannin.

Preferably, the polymer is selected from the group comprising polyester, polyolefin and a combination thereof. More preferably, the polyester is polyethylene terephthalate and the polyolefin is selected from the group comprising High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene, Ethylene vinyl acetate, and combinations thereof. Preferably, 0.1 to 5% by weight of Neem oil is mixed with 95 to 99.9% by weight of thermoplastic polymer.

According to another embodiment of the invention, the inventive concept of the present invention can similarly be applied to improve the bacteriostatic properties of molded polymer articles and need not be restricted to fabrics alone.

In order that those skilled in the art will be better able to practice the present disclosure, the following examples are given by way of illustration and not by way of limitation.

Example 1: Preparation of polymer containing 1% Neem oil
Slurry of purified terephthalic acid (6 kg) in ethylene glycol (4.5 kg) was esterified in an esterification reactor for 3.5 hours at 2600C and 2 bar nitrogen pressure. 70g of Neem oil was mixed with a small quantity of ethylene glycol and added to the molten esterification product. After an interval of 20 minutes, 300ppm antimony trioxide catalyst dissolved in 250ml of ethylene glycol was added. The molten oligomer formed as a result of the esterification was transferred from the esterification reactor to an autoclave to polymerize the oligomer to yield polyethylene terephthalate (PET). The temperature of the mixture was increased to about 2850C, while gradually reducing the pressure over 45 minutes to 1 mm of Hg to obtain the polymeric product PET. The intrinsic viscosity of the polymer was determined to be 0.617 dl/g (ASTM D4603) and di-ethylene glycol content was 1.86%. The polymer chips were crystallized at 140oC in an air oven.

Example 2: Preparation of Polymer containing 3% Neem Oil
Slurry of purified terephthalic acid (6 kg) in ethylene glycol (4.5 kg) was esterified in an esterification reactor for 3.5 hours at 2600C and 2 bar nitrogen pressure. 210g of Neem oil was mixed with a small quantity of ethylene glycol and added to the molten esterification product. After an interval of 20 minutes, 300ppm antimony trioxide catalyst dissolved in 250ml of ethylene glycol was added. The molten oligomer formed as a result of the esterification was transferred from the esterification reactor to an autoclave to polymerize the oligomer to yield PET. The temperature of the mixture was increased to about 2850C, while gradually reducing the pressure over 45 minutes to 1 mm of Hg to obtain the polymeric product PET. The intrinsic viscosity of the polymer was determined to be 0.597 dl/g (ASTM D4603) and di-ethylene glycol content was 1.90%. The polymer chips were crystallized at 140oC in an air oven.

Example 3: Manufacture of polymer yarn containing 1% and 3% Neem Oil
The crystallized polyester chips of Example 1 and 2, were extruded from a 36 hole spinneret at 2800 C, quenched using cold air at 180C, and taken up at a spinning speed of 1250 m/min on a first godet maintained at 800 C, and further drawn 2.8 X to a second roller at 3500 m/min maintained at 1450C, and then wound up to produce a fully drawn yarn (FDY) at a spinning throughput of 1.75 kg/hr. The yarn was knitted into a hose and tested for antimicrobial activity. Antimicrobial testing was carried out following the JIS L 1902 method. Bacteriostatic activity for both the yarn samples was found to be less than 2.0, indicating no antimicrobial activity.

Example 4: Detection of Azadirachtin in distillate sample
Azadirachtin, a chemical compound belong to limonoid group, is an active ingredient of Neem oil. As the yarn sample of Example 3 did not show any antimicrobial activity, the distillate from both the esterification reactor and the autoclave (of Example 3 were analyzed for Azadirachtin by HPLC. After analyzing the distillate, it was found that all the active content of the Neem oil, namely Azadirachtin, had remained in the autoclave distillate possibly because of the fine vacuum during polymerization and higher polymerization temperature. Since adding Neem oil prior to polymerization did not result in a product containing Neem oil, the following examples attempted to ascertain the effects of adding Neem oil to the already polymerized masterbatch directly during spinning.

Example 5: Preparation of PET masterbatch
70g of Neem oil was soaked in 280g of microporous PET and left overnight under vacuum at ambient temperature to yield PET masterbatch comprising Neem Oil. Neem Oil was absorbed into the PET due to the microporous structure of PET and the PET was found to still be free flowing. The PET is then extruded and comminuted into chips. These chips are hereinafter referred to as the “experimental PET masterbatch”.

Example 6: Manufacture of polymer yarn (Control PET)
Crystallized base polyester chips which were prepared using polyester made without adding Neem oil were extruded from a 36 hole spinneret at 2800 C, quenched using cold air at 180C, and taken up at a spinning speed of 1250 m/min on first godet maintained at 800 C, and further drawn 2.8 X to a second roller at 3500 m/min maintained at 1450C, and then wound up to produce a fully drawn yarn (FDY) at a spinning throughput of 1.75 kg/hr. The yarn was knitted into a hose and was used as the Control PET sample. Antimicrobial testing was carried out following the JIS L 1902 method.

Example 7: Preparation of polymer yarn from the chips of Example 5
The experimental PET masterbatch chips of Example 5 were fed to an extruder with crystallized base polyester chips prepared using polyester made without adding Neem oil. The crystallised base polyester chips have an intrinsic viscosity (IV) of 0.62 dl/g and were fed to the extruder while using a K-Tron feeder to maintain a masterbatch to base polyester ratio of 1:20 and total throughput of 1.75 kg/hr. The molten polymer mixture was extruded from a 36 hole spinneret at 2800 C, quenched using cold air at 180C, and taken up at a spinning speed of 1250 m/min on a first godet maintained at 800C, and further drawn 2.8 X to a second roller at 3500 m/min maintained at 1450C, and then wound up to produce a fully drawn yarn (FDY) of 75 denier. The yarn was knitted into a hose, containing 1% Neem oil. Antimicrobial testing was carried out following the JIS L 1902 method.

Example 8: Preparation of polymer yarn from the chips of Example 5
The experimental PET masterbatch chips of Example 5 were fed to an extruder with crystallized base polyester chips which were prepared using PET made without adding Neem oil. The crystallised base polyester chips have an IV of 0.62 and were fed to the extruder while using a K-Tron feeder to maintain a masterbatch to base polyester ratio of 3:20 and total throughput of 1.5 kg/hr. The molten polymer mixture was extruded from a 36 hole spinneret at 2800 C, quenched using cold air at 180C, and taken up at a spinning speed of 1153 m/min on a first godet maintained at 800C, and further drawn 2.6 X to a second roller at 3000 m/min maintained at 1450C, and then wound up to produce a fully drawn yarn (FDY) of 75 denier. The yarn was knitted into a hose, containing 3% Neem oil. Antimicrobial testing was carried out following the JIS L 1902 method.

Example 9: Dyeing of fabric
The knit hose (20 g) of Example 7 was dyed at 1100C for 45 mins in a 500 ml bath containing high energy dye blue-79 in an amount of of 1% (based on knit hose), and after dyeing, the hose was dried. The dried dyed hose was then subjected to antimicrobial test method JIS L 1902.

Example 10: Washing and antimicrobial testing of fabric
The knit hose (20 g) of Example 7 was washed 5 times according to ISO 6630: 6A 2000 using a front loading washing machine with 2 kg dummy weight, soft water, and European colorfastness establishment (ECE) non-phosphate reference detergent. The hose was then subjected to antimicrobial test method JIS L 1902.

Example 11: Preparation of polymer yarns with 1% Neem oil surface coating
The crystallized base polyester chips which were prepared using PET made without adding Neem oil were extruded from a 36 hole spinneret at 2800 C, quenched using cold air at 180C, and taken up at a spinning speed of 1250 m/min on a first godet maintained at 800 C, and further drawn 2.8 X to a second roller at 3500 m/min maintained at 1450C, and then wound up to produce a fully drawn yarn (FDY) at a spinning throughput of 1.75 kg/hr. The yarn was knitted into a hose and further using pad-dry-cure method, 1% Neem oil was coated uniformly on the surface of the fabric. Antimicrobial testing was carried out following the JIS L 1902 method.

Example 12: Washing fabric of Example 11
The knit hose of Example 11 was washed 5 times according to ISO 6630: 6A 2000 using front loading washing machine with 2 kg dummy weight, soft water, and ECE non-phosphate reference detergent. The hose was then subjected to antimicrobial test method JIS L 1902.

Table 1 shows a comparison of the physical properties and bacteriostatic activity of the fabrics prepared according to the preceding examples.
Sample of Neem content in (%) Addition point of Neem oil IV
(dL/g) Tenacity
(gpd) Processing after knitting Bacteriostatic activity (as shown towards Staphylococcus aureus
MTCC 6538 P) Bacteriostatic activity (as shown towards Escherichia coli ATCC 11229)
Example 3 1% After esterification but before polymerisation 0.60 3.0 Nil 1.51 1.45
Example 6 0 - 0.62 3.7 Nil 1.24 1.25
Example 7 1.0 During spinning 0.61 3.4 Nil 4.41 3.65
Example 8 3.0 During spinning 0.58 1.6 Washed once 3.00 2.30
Example 9 1.0 During spinning 0.61 3.4 Dyed with blue 3.81 3.88
Example 10 1.0 During spinning 0.61 3.4 Washed
5 times 3.50 3.55
Example 11 1.0 Surface coating 0.60 3.3 Nil 4.12 3.37
Example 12 1.0 Surface coating 0.60 3.3 Washed
5 times 1.41 1.35

The standard antimicrobial value of evaluation = bacteriostatic activity > 2.0

As is evident from Table 1, the Control PET fails in the test and the hose prepared in Examples 7 to 12 with the Neem oil during or after spinning i.e. as a surface coating passes the JIS L 1902 test, as the bacteriostatic activity is well above 2.0.

Also, as is seen from the Example 6, the hose was subjected to wash treatment for 5 times and the bacteriostatic activity was well above 2.0 indicating long lasting antimicrobial activity. From the foregoing Examples, it is clear that the bacteriostatic activity of Neem oil is optimal when Neem oil is added immediately before spinning or during or after spinning the yarn. It appears that Neem oil gets absorbed due to the microporous structure of PET and remains trapped within this microporous structure for at least 5 washes.

What has been described and illustrated herein are preferred embodiments of the invention along with some of their variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the claims that follow—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.

We Claim:

1. A process for preparing a polymer composition having bacteriostatic properties, the process comprising mixing 0.1 to 8% by weight of Neem oil with 92 to 99.9% by weight of thermoplastic polymer.

2. The process as claimed in claim 1, wherein the polymer is selected from the group comprising polyester, polyolefin and a combination thereof.

3. The process as claimed in claim 2, wherein the polyester is polyethylene terephthalate.

4. The process as claimed in claim 2, wherein the polyolefin is selected from the group comprising High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene, Ethylene vinyl acetate, and combinations thereof.

5. The process as claimed in claim 1, wherein 0.1 to 5% by weight of Neem oil is mixed with 95 to 99.9% by weight of thermoplastic polymer.

6. A polymer composition having bacteriostatic properties, the composition comprising 92 to 99.9% by weight of thermoplastic polymer and 0.1 to 8% by weight of Neem oil.

7. The composition as claimed in claim 6, wherein the thermoplastic polymer is selected from the group comprising polyester, polyolefin or a combination thereof.

8. The composition as claimed in claim 7, wherein the polyester is polyethylene terephthalate.

9. The composition as claimed in claim 7, wherein the polyolefin is selected from the group comprising High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene, Ethylene vinyl acetate, and combinations thereof.

10. The composition as claimed in claim 6, wherein the composition comprises 0.1 to 5% by weight of Neem oil.

Dated this 14th day of October 2014
(Fiona Desouza)
of Khaitan & Co
Agent for the Applicants
Reg No IN/PA-1561