FIELD OF INVENTION -

This invention relates to a process for making non DEHP PVC compounds suitable for the fabrication of containers for the storage of platelet concentrates and for making flexible devices and tubing for medical applications. Along with the preparation of the compound the invention also addresses the fabrication of sheets and containers with the novel PVC compound.

PRIOR ART:-

In the prior art known currently the platelet concentrates are produced by the platelet rich plasma (PRP) method. This method essentially consists of a short low speed centrifugation of whole blood to separate red cells and leucocytes and platelet rich plasma. The PRP is transferred into another container and then centrifuged at high speed to obtain cell free plasma and a platelet rich pellet. The platelet pellet is re suspended in about 50-60 ml of residual plasma after one and a half hours resting period at room temperature. The re suspended platelet concentrate held within a plastic container is stored in a platelet agitator maintained within a chamber at 22-23°c. This equipment keeps the platelets in free motion to enable their oxygenation through the walls of the container (made of plasticized PVC or specially formulated poly olefins). The platelet concentrate prepared by this method contains a relatively high number of leukocytes and red blood cells.

In the Buffy coat system, whole blood is subjected to high speed centrifugation into three layers - an upper layer of cell free plasma, a middle layer containing around 90% of the platelets and 70% of the leucocytes and a lower layer containing red cells. The plasma layer and the concentrated red cells are transferred to separate containers. The buffy coat is then kept overnight and centrifuged at low speed to separate an upper layer of platelet rich plasma and a lower layer containing red cells and leukocytes. In certain modifications, platelet preservative media are added to the buffy coat instead of plasma for dilution before centrifugation.

The platelet concentrates prepared by this method contain less than 107 leucocytes. This can further be reduced to less than 5x106 when automatic component separators are used. Platelets prepared by the PRP method are found to be more activated immediately after preparation. This might be due to the fact that the platelets during the second high speed spin are directly pressed against the material of the blood bags which result in a reaction. In the case of the buffy coat method, the platelets are cushioned against the leucocytes and red cell layers during the first high speed centrifugation.

The recovery of platelets by the PRP method is 60-75% whereas by the Buffy coat method for individual blood units (450ml) it is lower, in the range 40-60%. However, if buffy coats are processed after pooling, the recovery increases to 60-75%. The WBC contamination of platelets by the PRP method is 1-2 per 1000 platelets. For the buffy coat method for individual units of blood it is 1-2 per 10,000 platelets and is lowest for pooled platelets by the buffy coat method at 1-2 per 100,000 platelets.

The Metabolism of platelets is such that platelets get 85% of their energy from aerobic metabolism in which mainly glucose and substrates such as free fatty acids and amino acids are involved. The residual 15% of the energy of platelets is derived from anaerobic glycolysis, in which glucose is converted to lactate. The conversion of glucose to ATP by the oxidative mechanism is 18 times more efficient than anaerobic glycosis. When the containers in which platelets are stored cannot allow sufficient oxygen to get in to provide high oxygen partial pressure within the container, the oxidative metabolism shifts to anaerobic glycolysis resulting in increase of lactate and decrease of pH. The carbon dioxide produced during the oxidative pathway gets converted to bicarbonate which acts as the buffer system of plasma. The containers in which platelets are stored have a very critical role in maintaining the oxidative metabolism of the platelets. This can be achieved only if the permeability to oxygen of the containers is high. At the same time, the permeability to carbon dioxide also should be high enough to permit a good part of the carbon dioxide to diffuse out but it should not be too high which would permit too much of the C02 formed to get out in which case the production of the bicarbonate buffer would be compromised and pH would tend to increase beyond 7.2.

Optimal conditions for platelet storage involve a balance between aerobic and anaerobic glycolysis, enabling a pH in the range 6.8-7.2 by an adequate influx of oxygen and efflux of C02 from the container which also calls for a matching number of platelets and suitable substrate level during the period of storage.

There is an urgent need for the pooling of platelet concentrates as in the case of a bleeding thrombocytopenic patient, the generally accepted practice is to increase the platelet count by 50x109/L to provide hemostasis. This can be accomplished within one hour after transfusion by administering one unit of PC for each 10kg of body mass. The actual PC increment is only 2/3 of this. In general, a pool of 6 units per adult should be sufficient which may be increased to 10 units as required. This requirement defines the capacity and efficiency of the bag for storing pooled platelets.

When the quantity of stored platelets are high as in the case of pooled platelets prepared by the buffy coat method, the oxygen and carbondioxide permeability of the containers become very critical and difficult to achieve. The size of containers for the storage of pooled platelets prepared by the buffy coat method vary. The optimum size varies from 600ml capacity to 1200ml capacity, one litre being the preferred volume, keeping in view the essential requirements to keep the bags on platelet agitators at 22-23°C and ease of handling. The platelet units from 450ml blood to be stored in such containers generally vary from 4 to 6 and in some case it may even go to 10.

To obtain pooled platelet concentrate blood from six to ten whole blood derived platelets have to be separated and mixed both in the PRP-PC and BC-PC methods. In the apheresis method, the platelets are withdrawn from a single donor using special equipment called "Cell separator". The remaining components are returned to the donor 's blood circulation. The process collects only the platelets from the donor. The process reduces the chance of transfusion transmitted infections. Also infections due to multiple venepuncture are reduced. The apheresis platelets could be collected in the special bags made according to the present invention. Advantages are: No DEHP contamination and better preservation of platelet concentrates.

There are many piasticiers for PVC. But the plasticiser of choice for PVC has been di,-(2- ethyl hexyl) phthalate because of its high compatibility with PVC and very many desirable characteristics which it imparts to PVC. DEHP is however lipophilic and is extracted into blood and blood components stored in PVC bags containing this plasticizer. This is of concern particularly to newborns, very young children and patients who require regular blood transfusions. In consequence there is a strong move to replace DEHP with other non phthalate plasticizers. However DEHP has notable beneficial characteristics, the most important being its ability to protect RBC membranes which enables its safe storage for at least 42 days. This is a characteristic which is unmatched by other plasticizers. In the case of platelets, the leached DEHP has been found to lower the aggregation properties of platelets after around 72 hours of storage.

Tri (2-ethyl hexyl) tri mellitate (TEHTM) is a plasticizer with extremely low leachability. It is precisely because of this low leaching that TEHTM is not suitable as plasticiser for PVC containers for the storage of RBC beyond 21 days. However TEHTM is well suited for making containers for the storage of platelet concentrates. The oxygen and carbondioxide permeabilities of TEHTM plasticized PVC increases with increased plasticizer content. At higher plasticizer levels however the plasticized PVC becomes very pliable, have low mechanical properties and becomes sticky particularly after sterilization by autoclaving. Another factor to be considered is that TEHTM is invariably contaminated with up to 2% of DEHP because of the processing steps involved in its manufacture.

Another plasticizer developed by M/S Terumo Corporation for the storage of platelet concentrates is di, (n- decyl) phthalate. Bags made using this plasticizer have 1/100 of the leachability of DEHP plasticized bags. DNDP is also less toxic and less mutagenic. The lack of availability of this plasticizer at acceptable prices is a problem.

Another plasticizer, n-butryl, tri n-hexyl citrate has been found to be suitable for making containers for the storage of both red cell concentrates and also for platelets. Red cell concentrates could be stored for up to 42 days and platelet concentrates for up to 5 days. Platelets stored in such bags have reduced aggregation characteristics as in the case of DEHP caused by the leached plasticiser. The leaching of BTHC has also been reported to be high (Up to 400 ppm after seven days storage of platelets). Yet another area of concern is the high carbondioxide permeability of such PVC containers which result in increased pH levels of stored platelets if the initial platelet count is low. There is also the high price of BTHC to be considered.

Special poly olefins have been used by M/S. Baxter for the storage of platelets. Bags made of poly olefins are less suitable for centrifugation because of their hardness. Since they are less flexible, the platelets stored within such containers cannot be effectively shaken during storage with the result that the platelets do not get access to sufficient oxygen to maintain the oxidative metabolism of platelets. Since their resistance to heat is poor, polyolefin bags have to be sterilized at lower temperatures which involve longer sterilization times. Another problem is that they are not compatible with PVC material and so special techniques have to be adopted to make connections with PVC containers or tubes. Polyolefin containers have high permeability to carbon dioxide which causes, increase in pH of stored platelets when the platelet count is low.

OBJECT OF THE INVENTION:-

The main object of the present invention is to formulate a PVC composition comprising of Ultra high Molecular Weight suspension grade PVC and a non aromatic, non phthalate plasticizer.

Another object of the present invention is to prepare PVC compound comprising of plasticizing Ultra high Molecular Weight suspension grade PVC with a non aromatic, non phthalate plasticizer.

Another object of the present invention is to fabricate PVC sheets with formulated PVC composition and/or PVC compound.

Yet another object of the present invention is to use 1,2-cyclohexane dicarboxylic acid, di isononyl ester as plasticizer

Yet another object of the present invention is to fabricate PVC tubes based on formulated PVC composition and/or PVC compound and/or fabricated PVC sheets.

Yet another object of the present invention is to fabricate PVC containers using fabricated PVC sheets and/or fabricated PVC tubes and/or PVC compound and/or other components based on formulated PVC composition.

Yet another object of the present invention is to fabricate blood bag system comprising of atleast one fabricated PVC container.

Yet another object of the present invention is to fabricate blood bag system comprising of atleast one fabricated PVC container and atleast one fabricated PVC tube.

Yet another object of the present invention is to fabricate blood bag system comprising of plurality of fabricated PVC containers.

Yet another object of the present invention is to fabricate blood bag system comprising of plurality of fabricated PVC containers along with PVC tubes.

Yet another object of the present invention is to utilize the fabricated PVC tubes, PVC container and blood bag system for the collection and storage of platelet rich plasma and platelet concentrates separated and pooled from multiple units of blood.

Yet another object of the present invention is to fabricate PVC sheets, PVC container, PVC tube and blood bag system having oxygen permeability to meet the demands of the platelets stored in it, which is in the range of 1300 to 2000 ml per square meter per 24hrs at 25°C at normal pressure

Yet another object of the present invention is to fabricate PVC sheets, PVC container, and PVC tube and blood bag system having carbon dioxide permeability to meet the demand of the platelets stored in it which is in the range of 2500 to 4000 ml per square meter per 24hours at 25°C at normal pressure

SUMMARY OF THE INVENTION:-

The present invention relates to a formulation of PVC composition comprising of Ultra high Molecular Weight suspension grade PVC and a non aromatic, non phthalate plasticizer for use in making of PVC sheets and/or tubes and/or containers and/or blood bag system for the collection and storage of platelet rich plasma and platelet concentrates.

The present invention also relates to a process of preparing PVC compound comprising of plasticizing an Ultra High Molecular Weight suspension grade Poly Vinyl Chloride by the non-aromatic, non phthalate plasticizer, 1,2-cyclohexane dicarboxylic acid di isononyl ester (DINCH). The fabrication of PVC containers with the formulated composition and/or PVC compound comprises of extruding the compound into sheets and tubes and injection moulded to various components of appropriate dimensions according to the standard procedures. For the purpose of testing the property of the fabricated PVC components the process further includes the step of annealing at 120°c for 30 minutes and subsequent conditioning at room temperature for 48 hours.

DESCRIPTION OF THE INVENTION:-

The present invention relates to a formulation of PVC composition comprising of Ultra high Molecular Weight suspension grade PVC and a non aromatic, non phthalate plasticizer for use in making of PVC sheets and/or tubes and/or containers and/or blood bag system for the collection and storage of platelet rich plasma and platelet concentrates. The present invention also relates to a process for making PVC compound comprising of plasticizing Ultra High Molecular Weight suspension grade poly vinyl chloride by a non-aromatic plasticizer free from phthalates for use in making of sheets and/or tubes and/or containers for the collection and storage of platelet rich plasma and platelet concentrates separated from one or more units of human blood.

The invention also relates to fabrication of PVC compounds with formulated PVC composition for making flexible devices such as PVC tubes, PVC containers and blood bag system for medical applications.

Various new plasticizers have been developed by M/s BASF by the high pressure hydrogenation of phthalates. Among such products 1,2-Cyclohexane dicarboxylic acid, di isononyl ester (DINCH), is a plasticizer which has an excellent toxicological profile, no carcinogenicity, low migration characteristics and has a wide range of regulatory approvals. It is approved for toys and food contact applications. Indian Patent Application 254/CHE/2006 declares that DINCH plasticised PVC bags are suitable for the storage of units of platelet concentrates prepared by the PRP, buffy coat, and apheresis methods.

Indian Patent application No. 1407/CHE/2008 teaches that the deleterious aspects of BTHC plasticized PVC containers such as odor, too high carbon dioxide permeability and cost could be reduced by using blends of the plasticier with DINCH or DEHP.

DINCH plasticized platelet storage bags of 400-450 ml capacity are very well suited for the storage of platelets collected from one unit of blood (450ml). The notable advantage with this plasticizer is that the containers being DEHP free, there will be no DEHP contamination of platelets. The adverse effects of leached DEHP are thus eliminated. Further, the undesirable suppression of the aggregation of platelets is also eliminated.

Because of the limited range of permeability to oxygen, DINCH plasticized containers of capacity 1.0 litre made according to the formulations specified in Indian Patent Application No.254/CHE/2006 are not suitable for storing pooled platelets separated from more than three units of blood. The oxygen permeability (as also carbondioxide permeability) can be increased by increasing the DINCH level in the PVC sheet with which the containers are made. There are limitations to this procedure since high loading of DINCH in the PVC makes it very soft and sticky particularly after autoclaving. With PVC of K value 77, 80phr loading of DINCH gives a sheet with acceptable characteristics and markedly higher permeability to oxygen. Sheets made using more than 80 phr DINCH plasticized PVC of K value 77 are too soft, have poor strength and presents problems during extrusion. Adhesion of sheets during steam sterilization is also a problem. These difficulties can be overcome if PVC of higher K values are used.

Platelet pooling bags are generally designed to hold platelet concentrates separated from six to ten units of blood and have the preferred capacity of 0.6 to 1.0 Litres. The pooling bags must have the oxygen permeability to meet the demands of the platelets stored within. At the same times the carbondioxide permeability should be at a level which would allow a good part of the carbondioxide to escape but retaining enough C02 partial pressure within the bag so as to maintain sufficient bicarbonate for buffering and thus prevent fall of pH. The present studies show that DINCH levels of up to 120phr for Ultra High Molecular Weight PVC of K-value 77-90 meets the requirements of oxygen and carbondioxide permeability for platelet pooling bags of 0.6 to 1.0 litre capacity.

The present invention particularly relates to the development of highly specialized containers for the preservation and storage of pooled platelet concentrates separated from multiple units of blood, by the use of Ultra high Molecular Weight Poly vinyl Chloride plasticised with 1,2 - Cyclohexane dicarboxylic acid, di isononyl ester (DINCH).

The permeabilities to oxygen and carbondioxide of the PVC containers are very critical for the maintenance of an aerobic metabolism for the platelets. The anaerobic pathway to lactic acid has to be suppressed. Also the build up of bicarbonate buffer should be promoted by ensuring sufficient partial pressure of carbondioxide within the platelet storage bag. These are achieved by

a) The proper selection of the molecular weight distribution of the PVC as indicated by the K value.

b) The level of plasticiser loading - the higher the plasticiser level, the higher will be the permeability.

c) The thickness of the PVC sheet.

The characteristic of the Ultra High Molecular Weight PVC used in the present studies is given in Example -1. Examples-2&3 shows typical formulations for PVC bags meant for the storage of pooled platelet concentrates made using PVC of K value 90. The components as described were compounded in a batch compounding machine according to standard operating procedure, cooled in a cooler mixer and then pelletized.

The compound was then extruded into sheets and tubes and injection moulded to various components of appropriate dimensions according to the standard procedures. The sheets were annealed at 120°c for 30 mnts and then conditioned at room temperature for 48 hours before testing in order to reflect the performance of the PVC containers after sterilization

Example 1

Characteristics of PVC used in the present study

Example 2

A typical formulation for PVC Bags for the storage of pooled platelet
concentrates usina UHMW PVC of K value 90 (Formulation No 1)
Example-3 A typical formulation for PVC Bags for the storage of pooled platelet concentrates using UHMW PVC of K value 90 (Formulation No 2)

Table 1 (a) indicates the characteristics of the Ultra High Molecular Weight PVC
plasticised with DINCH.which was used in the present studies.

Table 1 (a) Characteristics of PVC sheets made from Ultra High Molecular
Weight PVC plasticised with DINCH.

Sheet thickness 0.40mm.

Table 1b shows the permeabilities to Oxygen and Carbondioxide of PVC sheets
made using PVC of K value 76 to 90 plasticised with DINCH at different levels. The
characteristics of two typical TEHTM plasticized PVC sheets are also given for
comparison.

Table 1b

Permeabilities of Oxygen and Carbon dioxide of sheets made using Ultra High
Molecular Weight PVC and DINCH Plasticiser

Table 1 (b) indicates the relationship between the K value of PVC, the level of loading of the plasticizer DINCH, and the permeability to oxygen and carbon dioxide of the sheets.

When the DINCH plasticizer level is increased from 62 to 80 phr, there is an increase in the permeability of Oxygen of 76 per cent and increase in the permeability of Carbon dioxide of 28 per cent. When UHMW PVC of K value of 90 was used at the same increased plasticizer level of 80 phr, there was reduction in the permeabilities of Oxygen and Carbon dioxide. At higher plasticizer levels there was significant increase of Oxygen permeability, while the permeability to carbon dioxide remained without much change.

However the permeability obtained for K-90 PVC at 80 to 120 phr levels of DINCH are much better in comparison with those obtained for K-77 PVC at 62 phr levels of TEHTM and DINCH which are Terumo penpol's standard formulations for platelet storage bags . Taking into account other parameters such as shore-A hardness, Tensile strength and Elongation at break, it was decided that formulations in which UHWM PVC of K value 90 was plasticized with 80-120 phr of DINCH would be most suitable for making platelet pooling bags.

In one of the preferred embodiment the present invention relates to a PVC composition for making of containers for collection and storage of platelet rich plasma and platelet concentrates separated from one or more units of human blood, comprising of an Ultra High Molecular Weight suspension grade poly vinyl chloride and a non-aromatic plasticizer free from phthalates.

In another preferred embodiment the present invention relates to a PVC compound made from a PVC composition, for making of containers for collection and storage of platelet rich plasma and platelet concentrates separated from one or more units of human blood, wherein the PVC composition is comprising an Ultra High Molecular Weight suspension grade poly vinyl chloride and a non-aromatic plasticizer free from phthalates.

In another preferred embodiment the invention relates to a process of preparing PVC compound from a PVC composition which comprises process of plasticizing an Ultra High Molecular Weight suspension grade poly vinyl chloride with non-aromatic plasticizer free from phthalates.

As such the invention is addressed to preparing a novel plasticized PVC composition made of Ultra High Molecular Weight suspension grade poly vinyl chloride plasticized by the non-aromatic plasticizer 1,2- cyclohexane dicarboxylic acid, di isononyl ester which is free from phthalates. According to the invention the K value of PVC as determined by ASTM D-1243 is 77 to 90 corresponding to an inherent viscosity of 1.25 to 1.50. As per the invention, 42-54% of plasticizer is utilized and more preferably 43 to 48% by weight of PVC. The invention also achieves fabricating PVC sheets with this novel composition and/or PVC compound. The invention also achieves making of PVC Containers with PVC composition and/or PVC compound and/or PVC sheets, According to the invention PVC tubes and blood bags systems comprising of plurality of PVC containers along with/without plurality of PVC tubes can be fabricated. The storage bags generally referred to as containers in the specification with the said fabricated PVC sheets exhibiting all the desired characteristics demanded for a container for storing blood platelet concentrates.

The invention has obtained the PVC sheet so fabricated for making the container which stores a life saving component like blood essentially desired characteristic of permeability to oxygen of 1300 - 2000 ml/sq.metre/24 hrs maintained at 25°C and at normal pressure for sheet thickness of 0.39 +/- 0.01 mm. Along with the permeability of oxygen the fabricated sheet also displaced the characteristic of permeability to carbondioxide of 2500 - 4000 ml/sq.metre/24 hrs at 25°C and at normal pressure. Furthermore as per the industry standards to maintain the above ideal permeability desired for the blood storage container, the thickness of such sheets can range from 0.35 - 0.45 mm. In specific the most preferred size is 0.39 +/- 0.01 mm. The preferred permeability is made available with the fabricated sheet as per the invention.

The function and performance of the platelet storage bags were assessed as follows:-
Blood of the same blood group collected from four donors in each case, was separated into plasma, red blood cells and buffy coat by following Terumo's standard procedure. The buffy coats were pooled, diluted with plasma and separated into platelet concentrates, which was filtered through Terumo's leucocyte filters and collected in the test bags of 450 ml capacity made using PVC of K value 90 plasticized with DINCH plasticizer. The bags were kept in standard platelet agitators maintained at 22-23°C. Samples were taken at specified intervals and tested for the parameters given in Table-2

Table 2

Biochemical Parameters Studied

The studies showed that blood bags made using formulations in which Ultra High Molecular Weight PVC of K-value 90 plasticized with 80 to 120 phr of DINCH met the requirement of all the tests specified in Table 2.The results showed that platelet concentrates pooled from four units of blood of normal platelet content could be stored in a viable condition in 450 ml capacity blood bags made according to the present invention, for at least six days. The surface area of the 450 ml capacity pooling bags used in this study was 416 sq. cms. The surface area of 1 litre capacity bags is 740 sq. cms. This implies that up to 7 units of platelets could be collected and stored in one litre capacity bags.

The special bags for the storage of multiple units of platelet concentrates are made as separate units and not as part of an interconnected blood bag system.

An excellent procedure for the separation of platelet rich plasma is by the buffy coat method using Top and bottom bags for the initial blood collection and separation. The final storage of platelet concentrates is done in special bags made using Ultra High Molecular Weight PVC plasticized with DINCH plasticizer according to the present invention.

DINCH plasticized special bags are equally suitable for the storage of high quality platelet concentrates prepared by other methods such as for example the platelet rich plasma method, the single donor apheresis procedure or the TACSI procedure of Terumo Corporation.

In actual practice the buffy coat pooling method in conjuction with the leucocyte filtration of pooled platelets is a very convenient and reliable procedure. In addition, the operating and running expenses are very low as compared to the apheresis method.
As such the present invention is addressed to preparing a novel plasticized PVC composition for the storage of platelet concentrates and more particularly pooled platelet concentrates. The invention also achieves fabrication of PVC sheets, tubes and injection moulded components with PVC composition and/or PVC compound. The invention also achieves making of blood bags, the said PVC containers meeting all the desired characteristics required for a container for storing platelet concentrates.

Although the novel PVC formulation developed, is described as compounds converted into film and tubes and then to containers for the storage of platelet concentrates, the formulations may also be used for fabricating medical devices such as tubing of various types. One such specific application is for making of deformable tubes for use with peristaltic pumps. Tubes made using Ultra High Molecular Weight PVC of K value 90 to 100, plasticized with DINCH have low wearing rate during the squeeze push action typical of peristaltic pump operation. The use of DINCH as plasticizer is of particular importance. Unlike DEHP, BTHC or DEHA plasticized tubes, DINCH plasticized tubes have very low leach ability and is non toxic. DINCH has the additional advantage of having improved processability.

The examples and tables given herein are only for the reference purpose and for better understanding of the subject matter. Persons skilled in the art will understand the referred material and specification and the invention shall not be restricted to the details disclosed herein for the purpose of the understanding of the subject matter by the skilled persons. The scope of the invention shall be to the extent as shall be understood by the skilled persons in the art. The specification shall not be limited only to the extent as specifically disclosed in the specification.

We Claim,

1. A PVC composition for making of containers for collection and storage of platelet rich plasma and platelet concentrates separated from one or more units of human blood, characterized in comprising an Ultra High Molecular Weight suspension grade poly vinyl chloride and a non-aromatic plasticizer free from phthalates.

2. A PVC compound made from a PVC composition, for making of containers for collection and storage of platelet rich plasma and platelet concentrates separated from one or more units of human blood, wherein the said PVC composition is characterized in comprising an Ultra High Molecular Weight suspension grade poly vinyl chloride and a non-aromatic plasticizer free from phthalates.

3. A process of preparing PVC compound from a PVC composition which comprises the process of plasticizing an Ultra High Molecular Weight suspension grade poly vinyl chloride with non-aromatic plasticizer free from phthalates.

4. The said Ultra High Molecular Weight suspension grade poly vinyl chloride of claim 1, 2 or 3 has a K-value as determined by ASTM D-1243 of 77 to 90 corresponding to an inherent viscosity of 1.25 to 1.50.

5. The said plasticiser of claim 1, 2 or 3 is 1,2-cyclohexane dicarboxylic acid, di isononyl ester

6. The PVC composition claimed in claim 1,2 or 3 is such that the plasticiser comprises 42-54% and more preferably 43 to 48% by weight of the PVC.

7. A PVC sheet made with PVC composition as claimed in claim 1.

8. A PVC sheet made with PVC compound as claimed in claim 2.

9. A PVC container made with PVC composition as claimed in claim 1.

10. A PVC container made with PVC compound as claimed in claim 2.

11. A PVC container made with PVC sheet as claimed in claim 7 or 8.

12. A blood bag system made with PVC container as claimed in Claim 9,10 or 11 which comprises of a plurality of said PVC containers.

13. A blood bag system made with PVC container as claimed in Claim 9,10 or 11 which comprises of a plurality of said PVC containers and plurality of connecting PVC tubes.

14. The PVC sheet as claimed in claim 7 or 8, wherein the PVC sheet has permeability to oxygen of 1300 to 2000 ml per square meter per 24hrs at 25°C at normal pressure for sheet of thickness of 0.39 +/- 0.01 mm.

15. The PVC sheet as claimed in claim 7 or 8 wherein the PVC sheet has permeability to carbondioxide of 2500 to 4000 ml per square meter per 24hours at 25°C at normal pressure.

16. The PVC sheet as claimed in claim 7 or 8, wherein the thickness of PVC sheet for containers used for storage of pooled platelets is in the range 0.35 to 0.45mm and more preferably 0.39 +/- 0.01 mm.