AU648645B2 - Treated tubes - Google Patents

Description

OPI DATE n7/09/7q AOJP DATE 15/10/92 APPLN. IT 1?087 7q? PCT NUMBFR PCT/AlIq2/00n6 INTERNAl ,REATY (PCT) (51) International Patent Classification 5 B29C 71/02, A61B 5/14 A61L 31/00 Al (11) International Publication Number: (43) International Publication Date: WO 92/13708 20 August 1992 (20.08.92) (21) International Application Number: (22) International Filing Date: 7 Priority data: PK4511 7 Februal PCT/AU92/00046 February 1992 (07.02.92) ry 1991 (07.02.91) AU (81) Designated States: AT (European patent), AU, BE (European patent), CA, CH (European patent), DE (European patent), DK (European patent), ES (European patent), FR (European patent), GB, GB (European patent), GR (European patent), IT (European patent), JP, LU (European patent), MC (European patent), NL (European patent), SE (European patent), US.

Published With international search report.

445 (71) Applicant (for all designated States except US): MEDIX IN- TERNATIONAL PTY. LTD. [AU/AU]; 2 Montefiore Street, Fairfield, VIC 3078 (AU).

(72) Inventor; and Inventor/Applicant (for US only) PARSONS, Joseph, Red\ ers, Buller IGB/AU]; 20 Moira Avenue, Ferntree Gully, VIC 3156 (AU).

(74) Agent: GRIFFITH HACK CO.; 601 St. Kilda Road, Melbourne, VIC 3004 (AU).

(54) Title: TREATED TUBES (57) Abstract A blood or body fluid collection tube (20) 28 moulded in polyolefin to be open at one end and the interior surface of the tube is flamed treated to at least two-thirds of its depth from the open end. The flaming of the interior surface of the tube is carried out by use of a burner (22-25) configured to define in use closely 26 27 spaced tiered rings of flame that engage the interior of fl the tube. An apparatus for flame treating blood or body fluid collection tubes moulded in a polyolefin comprises a carriage (13) arranged to support a plurality of 21 tubes (20) in an array with the axis of the tubes extend- ing vertically, a burner assembly (12) including a nlurality of burners (22-25) each having a burner hea', of di- A 22 2 ameter to fit within the tubes (20) and means to cause relative displacement of the burner asse.mbly and the carriage to introduce the head of the burners into the 43 tubes to ensure direct flame contact with the interior surface of the tubes. 0 n' PCT/ AU92 000 4 6 RECEVEO0 2 2 AFR 1992 1 Title Treated Tubes Field of the Invention This invention relates to the treatment of synthetic plastics tubes that are used for the collection of blood or body fluids. In particular, the invention relates to tubes that are used for the collection of blood for separation into clot/serum fractions.

Prior Art Synthetic plastics blood collection tubes have been suggested in the past due to the shatter resistance as compared to glass collection tubes. The handling of blood has in recent times become a hazardous operation and a number of proposals have been made to reduce the likelihood of spillage. Clearly the use of synthetic plastics tubes instead of brittle glass tubes assists in reducing the likelihood of spillage. Blood collection tubes are used for a variety of purposes and testing procedure. In tests where there it is necessary for the blood to clot or for ,c SUBSTITUTE SHEET RECEIVEO 2 2 APR 13992 separation of the red cells and serum, plastics tubes have proved unsatisfactory. It has been discovered that a clotting agent has to be added to the blood with plastics tubes to promote clotting. The addition of the agent may interfere with the tests that are subsequently done on the blood samples. It is also known to separate red cells and serum by placing tubes containing blood and a silicone plug in a centrifuge. The relat-ve specific gravities of the red cells and serum as well as the silicone plug ensure that the red cells collect at the bottom of the tube to be separated from the serum with the plug acting as an interface. However, unless there is a good bond or adhesion between the periphery of the plug and the wall of the tube there is a danger that there will be contamination through flow between the red cells and serum. Synthetic plastics tubes suffer in this regard due to the high surface tension that is present between the plug and the wall of the tube. The wall tends to have a slippery inner surface after the moulding process which causes movement of the plug and can result in contamination of the separated fractions especially over a lengthy period and during transportation.

It is these problems that have brought about the present invention.

Summary of the Invention According to the present invention there is provided a blood or body fluid collection tube moulded in plastics characterised in that at least part of the interior of the tube is flamed treated.

Preferably, the plastics material is a polyolefin such as polyethylene or polypropylene.

Preferably, the tube is open at one end and the interior surface of the tube is flamed to at least two-thirds of its depth from the open end.

d SUBSTITUTE SHEET r V 2 00046 E'd '2 3 APR 1992 -3- According to the present invention there is further provided a method of treating a blood or body fluid collection tube comprising subjecting at least a portion of the interior of the tube to flame contact.

According to the present invention there is still further provided an apparatus for flame treating blood or body fluid collection tubes moulded in plastics comprising a carriage arranged to support a plurality of tubes in an array with the axis of the tubes extending vertically, a burner assembly including a plurality of burners each having a burner head of diameter to fit within the tubes and means to cause relative displacement of the burner assembly and the carriage to introduce the head of the burners into the tubes to ensure direct flame contact with the interior surface of the tubes.

Description of the Drawings An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side elevational view of apparatus for flame treating plastics tubes, Figure 2 is a plan view of a carriage assembly for the tubes, Figure 3 is an enlarged view of the detail shown within the circle A of Figure i, aid Figure 4 is a cross-sectional view taken along the lines X-X of Figure 3.

General Discussion of Flame Treatment of Plastics Flame treatment is considered to be the most versatile method for the pre-treatment of polyolefin surfaces. Flame treatment or flaming comprises exposing the plastic surface to a suitable oxidising flame for a period in the range of 0.2 to 3 seconds. This treatment brings about a change of the polymer surface which makes it wettable and permits a strong adhesive bond between the moulding surface and any coating that may need to be 1SUBSTITUTE SEET 1 SUB5TITLUTE S~EET7 FC 0 0 U 6 RECEIVE 2 3 APR 1992 -4applied to the surface. Flame treatment systems include linear conveyors on which the article to be treated may be rotated as it passes through the flame. The burner is essentially a piloted burner with a row of high velocity jets with directional force in the flame supported by a low velocity pilot system. The general shape of the flame is similar to a single row of tooth tufts. There are a variety of flame treatment variables that need careful control. The major flame treatment parameters to be controlled if optimum flaming conditions are to be used are as follows: a) Gas/air ratio. This is dependant on the type of gas used (town gas, methane, propane and butane are suitable). A laminar flow flame is preferable to a turbulent flame.

b) Distance of the burner to the moulding surface.

c) Speed of rotation of the mould in the frame.

This is applicable to cylindrical mouldings only and is not essential.

d) Residence time of the moulding in the flame.

It has been discovered that the gas/air ratio is the most important and critical factor in the flame pre-treatment. It is recommended that the gas/air flow be maintained at a predetermined level by the attachment of meters to both the gas and air supply lines. It is possible either to under or over treat polyolefin surfaces which can detrimentally affect the quality of the end product.

Before a production run starts with a given moulding, experiments are usually carried out to decide accurately the optimum flaming conditions. Once optimum conditions have been established, the apparatus should be set at these conditions and routine checks made to ensure that variations do not occur.

T L S, U 3 STI-A UT S E iCT A T. i 4 6 SECE\E 2 3 APR 1992 Description of the Embodiment The blood collection tubes are injection moulded in polypropylene with a multi-cavity die injection moulding machine. Whilst the tubes are preferably moulded in polypropylene, it is understood that other polyolefin plastics such as polyethylene can be used in the manufacture of the tubes. Whilst many of the tubes manufactured from the injection moulding machine are then dosed with additives for use in the blood collection and testing techniques the tubes that are for use in blood separation and blood clotting tests are then passed to flame treatment apparatus The flame treatment appiratus 10 is illustrated in Figures 1 to 4 and essentially comprises a carriage assembly 11 that conveys the tubes 20 in an upstanding configuration beneath an overhead burner assembly 12. The flame treatment is carried out by placing the tubes 20 on a carriage 13 that is displaceable longitudinally along a pair of spaced rails 14 and 15. A rack 16 is arranged to accommodate four tubes 20 each with its axis extending perpendicularly. The rack 16 is mounted centrally about linear bearing assemblies 17 and 18 that are arranged to be a sliding fit on the rails 14 and 15. An electric motor or pneumatic cylinder (not shown) is provided to displace the carriage 13 along the rails in the direction of the arrow shown in Figure 2. The carriage 13 is arranged to engage a stop 30 positioned at the end of the rails 14 and 15. This stop 30 has a switch 31 that is actuated by contact with the end of the carriage 13.

The burner assembly 12 is positioned above the carriage assembly 11 and comprises a rectangular fuel and air mixing manifold 21 with four equally spaced downwardly extending burners 22, 23, 24, and 25. Each burner is of a diameter so that it can fit within the interior of the blood collection tube 20. The fuel mixing manifold 21 is coupled to a source of gas 26 which may be town gas, liquid r-YiF'UB7STt17TE SiiE2T RECEIVED2 3 APR 1992 -6petroleum gas or butane gas and a source 27 of air or oxygen. The assembly 12 is mounted to be vertically displaceable by means of a pneumatic cylinder 28 which is bolted centrally to the upper surface of the manifold 21.

The operation of the pneumatic cylinder 28 is programmed to cause the whole assembly 12 to move down a calculated distance in which the tips of the burners 22 to 25 enter the tubes 20 and then retract to an inoperative position as shown in Figure i. When the carriage 13 is in the position against the stop 30, the switch 31 activates the cylinder 28 to cause the burner assembly 12 to be lowered so that each burner extends into the blood collection tubes to a predetermined depth. The assembly is designed so that the penetration of each burner 22 to 25 into the blood collection tube 20 is to approximately two-thirds of the length of the tube 20. The gas/air mixture is expelled from each burner at its free end and the burner is specifically designed to have a flame that will contact the wall of the tube as the burner is lowered into the tube.

The profile and constituent of the flame and the speed at which the flame passes down the interior surface of the blood collection tube are important criteria in ensuring effective flaming of the tube interiors.

Each burner comprises a hollow tube that carries the gas/air mixture from the manifold. A multi splined solid steel insert 40 is a force fit into the hollow end of the burner tube 22 so that the splines 41 define a plurality of axially extending gas passageways 42. The insert 40 terminates in a metal disc 43 of diameter slightly greater than the outside diameter of the burner tube 22. A second annular disc 44 is also secured to the insert 40 at a position between the end of the tube and the end disc 43. Both discs 43 and 44 serve to force the gas to flow radially to form closely spaced rings of flame to project outwardly to touch the interior surface of the plastics collection tubes 20. The collection tubes are NT SU33Ti7UTE S;rEET PCTi AU U U 46 RECEIVED 23 APR 1392 -7designed to have either a 15 or 13 millimetre outside diameter. The burners are designed to define about a 3 millimetre gap on diameter or a one and a half millimetre gap on each side between the each of the burner outside diameter and the collection tube interior. The burner tube 22 may also be provided with a series of apertures equally spaced around the periphery of the wall adjacent the end of the tube. These additional apertures can provide a third auxiliary ring of flame to act as a backer to the tiered rings defined by the discs 43 and 44. The splined insert is designed to define between ten and sixteen axially extending gas passageways 42. The upper disc 44 has the effect of scooping Vart of the gas/air mixture away from the end of the burner to provide a secondary burn which is before the main flame at the disc 43 at the end of the burner. This arrangement provides an intense flame in a two tier configuration and overcomes the danger of the flame being snuffed out as the burner is positioned within the confines of the interior of the tube.

The apparatus is such that the flame engages the wall of each tube along two-thirds of the length of the tube as the burner descends into the tube to be pulled clear of the tube from the upper end. The passage of each burner into the tube is arranged to be between a quarter and half a second and it has been discovered that this exposure is sufficient for the interior surface of the tube to lose its oily smooth exterior and reduce the surface tension to the desired level.

It is understood that for efficient operation of the apparatus described above, precise control and servo mechanisms need to be utilised to ensure exact indexing of the carriage 13 as well as precise and correctly timed lowering of the burner assemblies 12. It is considered that those skilled in this art would envisage a variety of electrical, electronic and mechanical equivalents to the apparatus described above. One alternative is to use a 0?' i UST:UTE SHEE£T ~uZ Rd2iJU 4 6 RE6 8I Ed 3 AEPR 1932 single burner tube could be transported on a rotary or linear indexing apparatus. It is further understood that whilst in the preferred embodiment the burners are lowered into the tubes in an alternative situation the system could be such that the tubes are raised and lowered against the burners. The burner design is also understood to be but one on many burners that operate efficiently in closed environments of the kind described.

The flaming pror-:ei~ alters the characteristic of the interior surface of the tubes whilst reducing the surface tension. These characteristic changes allow a silicone or gel plug to adhere in an improved manner to the wall of the tube after centrifugation. It has been discovered that where a gel plug is used in untreated plastic tubes, the gel forms a meniscus which has the effect of allowing the gel plug to creep along the length of the tube. The result of this creep is that there is enzyme and/or chemical seepage which can occur between the gel and tube wall allowing contamination of the red cells and serum.

Furthermore, where the tube is to be used in clotting tests it is important that the blood has an opportunity to adhere to the wall of the tube to improve clotting. The flame treatment reduces and/or eliminates the oil-like surface finish that is conventionally formed on injection moulding polyolefins. By reducing the surface tension and removing the oil like surface finish there is an improved chance of the blood adhering to the wall of the tube thereby increasing the blood clotting rate to an acceptable level.

Su"ST7UTE SH-EET Vr-~'

Claims (7)

1. 2. The collection tube according to Claim 1 characterised in that the plastics material is a polyolefin such as polyethylene or polypropylene.
2. 3. The collection tube according to either Claim 1 or Claim 2 characterised in that the tube is open at one end and the interior surface of the tube is flamed to at least two-thirds of its depth from the open end.
3. 4. A method of treating a blood or body fluid collection tube~comprising subjecting at least a portion of the interior of the tube to flame contact. The method according to Claim 4 comprising the steps of flaming the interior of the tube from its open end to at least two-thirds of its depth.
4. 6. The method according to Claim 5 wherein the naked flame on a gas burner is rapidly passed over the interior surface of the tube.
5. 7. The method according to Claim 6 comprising rapidly lowering and raising a gas burner with a naked flame into the interior of each tube.
6. 8. The method according to Claim 7 wherein the flaming of the interior surface of the tube is carried out by use of a burner configured to define in use closely spaced tiered rings of flame that engage the interior of the tube.
7. 9. An apparatus for flame treating blood or body fluid collection tubes moulded in plastics comprising a carriage arranged to support a plurality of tubes in an array with the axis of the tubes extending vertically, a burner assembly including a plurality of burners each having a burner head of diameter to fit within the tubes and means to cause relative displacement of the burner assembly and the carriage to introduce the head of the burners into the tubes to ensure direct flame contact with the interior surface of the tubes. 2 UBSTrTUTE SIEET J SCT AU-2 000 4I 6 ECEIVEO 2 3 APR 1932 10 Apparatus according to Claim 9 wherein each burner head comprises a plurality of axially extending gas passageways terminating in an end disc with an auxiliary disc positioned across the gas passageways spaced from the end disc whereby in use the burner hc-d defines a tiered flame. 1-C -1,O SStJBS737iJTE SiEET SNEE