Title of Invention

A PROCESS FOR PRODUCING PLASTICIZED POLYVINYL CHLORIDE (PVC) HAVING IMPROVED RESISTANCE TO LEACH PLASTICIZER

Abstract Process for prodLlcing plasticized polyvinyl chloride (PVC5 having improved resistance to leach plasticizer t.lhich comprises preparing a hydroxyl terminated polyurethane prepolymer (component A) by reacting cycloaliphatic diisocyanate and a polyol component at a temperature of tei to 15ei C, in the presence of a tin catalyst to obtain component A, and drying said component A; subjecting said dried component A to the step of treatment with a diisocyanate (component B) at a temperature of 40 to 100 C to obtain resinoLls prepolymer adhesive; subjecting a cleaned and dried PVC material to a step of treatment with said prepolymer adhesive to obtain coated PVC products, curing said coated PVC products, cleaning and drying to obtain treated plasti- cized polyvinyl chloride.
Full Text

This invention relates to a process for producing plasticized polyvinyl chloride (PVC) having improved resistance to leach plasticizer.
The use of plasticized poly (vinyl chloride) for biomedical applications is mainly as extra corporeal tubing’s and blood bag. The performance of the products manufactured from the plasticized poly (vinyl chloride) is dependent generally upon the interaction between the product and the surrounding medium. In most of the applications, plasticized poly (vinyl chloride) is in contact with some kind of surrounding liquid medium. During manufacture of plasticized poly (vinyl chloride) sheet di-2 ethyl hexyl phthalate (DEHP) is added as plasticizer to plasticize the rigid poly (vinyl chloride) polymer and to get the desired product. But with time, this plasticizer migrate to the surrounding liquid medium leading to create brittleness and early failure of the product. In application where no liquid medium is in contact with the product, migration of plasticizer takes place due to environmental aging, and known as sweating. The migration of plasticized/ is blood and its constituent stored in bag is an. undesirable event. Because the plasticizer DEHP is metaboffished to give monoethyl hexylphthalate (MEHP) in vivo and cause cardiotoxic effect on human heart muscle. Hypotension and cardiac arrest occurred in rats following the infusion of MEHP when circulating blood levels exceeded 75 ug per ml.. In this connection, reference is invited to (G.ROCK, Transfusion 30(8),

767(1990), The therapeutic level of DEHP for human at no effect level is 60 ug/kg body weight per day. (A.S.CHAWLA and I.HINBERG.BIOMAT. ART.CELL & IMMOB. BIOTECH 19(4) 761-783(1991). Higher doses of DEHP have been found to be mutagenic and teratogenic. Therefore, the performance of the products manufactured from plasticized poly (vinyl chloride) largely depends on its resistance to leach DEHP into the surrounding medium.
OBJECTS
An object of this invention to propose a process for chemical treatment of polyvinyl chloride materials which is not only reliable but also simple and economical.
Further objects and advantages of this invention will be more apparent from the ensuing description.
At the outset of the description which follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only an exemplary embodiment and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and reading of the invention and not intended to be taken restrictively.
DESCRIPTION OF THE INVENTION
According to this invention, there is provided a process for

producing plasticized poly (vinyl chloride) having improved resistance to leach plasticizer which comprises subjecting cleaned PVC material to treatment with a prepolymer adhesive of polyurethane and allowing to cure to obtain a transparent and flexible product.
According to this invention is further provided a process for the preparation of a resinous prepolymer adhesive .
In accordance with this invention, the PVC material is subjected to a first step of cleaning with a non-polar solvent, and then to a second step of cleaning in an ultrasonic cleaner using a detergent solution, which is then dried.
Basically, the steps of cleaning and chemical treatment are broadly carried out on an experimental basis as follows :
I. Initially, cleaning of plasticized poly (vinyl chloride) product is carried out using a non-polar organic solvent for 1-5 mins. to remove surface-adhered plasticizers and lubricants, etc. followed by cleaning in an ultrasonic cleaner using a detergent solution and demonized water, and then dried at the temperature of 30-70’C for 10-40 hrs..
II. Chemical treatment of cleaned and dried PVC product is carried out using a prepolymer adhesive of polyurethane.

(a) An aliphatic prepolymer adhesive of polyurethane was prepared by reacting two component mixtures containing component A and component B, Component A is a hydroxyl terminated polyurethane prepolymer and Component B is a diisocyanate. Component A was prepared with the reaction between a cycloaliphatic diisocyanate and excess polyol having trifunctionality and nitrogen atom in the presence of a tin catalyst at 70-150"‘ C for a duration of 30-180 mins, in an inert atmosphere using an amide solvent. The resin was dried. This dried resin A was reacted with Component B at 40-100 *’C for a duration of 2-20 mins.. The resinous prepolymer adhesive was used for coating the PVC product.
(b) The clean PVC product was dipcoated for 1 -10 mins. using the prepolymer adhesive of polyurethane immediately after the preparation of prepolymer adhesive. Dipcoating was moderated using a ketone solvent.
(c) Dipcoated products were then cured at 40-120 C for a duration of 10-50 hrs..
(d) The chemically modified PVC product is then cleaned in running water, demonized water and dried at 40-70’C for 1-4 hrs,.

chloride) sheet and tube containing of 30 phr of diethyl hexyl phthalate and 10 phr of dioctyl adipate plasticizers.
Calendared PVC sheet (0.35mm thickness) and extruded PVC tube were chemically treated as detailed above. The coating thickness is 0.18mm in each side of a PVC sheet. The chemically treated PVC products were exposed to hexane {a 'hard' solvent capable of extracting good amount of DEHP), liquid paraffin (a 'soft' solvent) and blood (with anti-coagulant) for a period 552 h at 28/4 C. The weight loss in these media were determined by drying the solvent-exposed modified PVC product. Unmodified commercially available PVC products were used as control. The amount of loss of plasticizer in the modified and unmodified PVC products are shown below :



During the exposure in the media, the modified materials remain transparent and flexible. The modified materials exposed to hexane and blood did not harden as could be observed in unmodified materials. The modified PVC materials are compatible with blood as the hemolytic potential is within the acceptable limit.




WE CLAIM
K A process for producing plasticized polyvinyl chloride (PVC) having improved resistance to leach plasticizer which comprises preparing a hydroxyl terminated polyurethane prepolymer (component A) by reacting cycloaliphatic ditsocyanate and a polyol component and drying said component A;
subjecting said dried component A to the step of treatment with
a diisocyanate (component B) to obtain a resinous prepolymer
adhesive;
subjecting a cleaned and dried PVC material to a step of treatment with said prepolymer adhesive to obtain coated PVC products curing said coated PVC products, cleaning and drying to obtain treated plasticized polyvinyl chloride.
2. A process as claimed in claim 1 wherein said polyol is in
excess of the cycloaliphatic diisocyanate.
3. A process as claimed in anyone of claims 1 or 2 wherein said polyol has trifunctionality and nitrogen atom.
4. A process as claimed in anyone of claims 1-3 wherein said process for the preparation of component A is carried out in an amide solvent in the presence of a catalyst in an inert atmosphere.
5. A process as claimed in anyone of claims 1-4 wherein the preparation of component A is carried out at a temperature of 70-150
6. A process as claimed in anyone of claims 1-5 wherein the preparation of component A is carried out for a period of time ranging from 30-180 mins..

7. A process as claimed in claim 1 wherein for the preparation of component A, a tin catalyst is used.
8. A process as claimed in claim 1 wherein the step of treating dried component A with component B is carried out at a temperature of 40-1OO’C.

9. A process as claimed in claim 1 wherein the step of treating
t A with component B is carried out for a period of
2-20 mins-.
10. A process as claimed in claim 1 wherein the PVC material is
clear>ed using a non-polar organic solvent for 1-5 mins. followed
by cleaning in an ultrasonic cleaner using a detergent solution
and demonized water.
11. A process as claimed in claim 1 wherein the P’C material
o after being cleaned is dried at a temperature of 30-70 C.
12* A process as claimed in anyone of claims 1-11 wherein the PVC
material is dried for a period of 10-A0 hrs..
13. A process as claimed in claim 1 wherein the step of treatment
of the PVC matter al with said adhesive the
PVC material in said adhesive for a period of 1-10 mins..
14. A process as claimed in claims 1 Ic 13 wherein the step of
dip coating is moderated using a ketone solvent.
15. A process as claimed in claim 1 wherein the step of curing is
o effected at 40-120 C.
16. A process as cI aimed in claim 1 wherein said coated PVC
product is cleaned in running water.
17* A process as c1 aimed in claim 1 wherein said coated PVC
o product is dried at 40-70 C.
18. A process as claimed in claims 1 S drying is carried out for 1-4 hrs. .
19. A process for producing plasticized polyvinyl chloride (PVC)
having improved resistance to leach plasticizer substantially as
herein described and illustrated w i th reference to the examples-


Documents:

1020-mas-2001-abstract.pdf

1020-mas-2001-claims filed.pdf

1020-mas-2001-claims granted.pdf

1020-mas-2001-correspondnece-others.pdf

1020-mas-2001-correspondnece-po.pdf

1020-mas-2001-description(complete)filed.pdf

1020-mas-2001-description(complete)granted.pdf

1020-mas-2001-form 1.pdf

1020-mas-2001-form 26.pdf

1020-mas-2001-form 3.pdf

1020-mas-2001-other documents.pdf


Patent Number 211919
Indian Patent Application Number 1020/MAS/2001
PG Journal Number 02/2008
Publication Date 11-Jan-2008
Grant Date 13-Nov-2007
Date of Filing 21-Dec-2001
Name of Patentee SREE CHITRA TIRUNAL INSTITUTE FOR MEDICAL SCIENCES & TECHNOLOGY
Applicant Address INDIAN INSTITUTE OF BIOMEDICAL TECHNOLOGY WING, POOJAPPURA, THIRUVANANTHAPURAM 695 012,
Inventors:
# Inventor's Name Inventor's Address
1 MUTHU JAYABALAN C/O SREE CHITRA TIRUNAL INSTITUTE FOR MEDICAL SCIENCES & TECHNOLOGY, AN INDIAN INSTITUTE OF BIOMEDICAL TECHNOLOGY WING, POOJAPPURA, THIRUVANANTHAPURAM 695 012,
2 PAMPADY KANDATHIL PHILIP LIZYMOL C/O SREE CHITRA TIRUNAL INSTITUTE FOR MEDICAL SCIENCES & TECHNOLOGY, AN INDIAN INSTITUTE OF BIOMEDICAL TECHNOLOGY WING, POOJAPPURA, THIRUVANANTHAPURAM 695 012,
PCT International Classification Number A61J 1/10
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA