GB1562235A - Flexible plastics material sachet - Google Patents

Description

(54) FLEXIBLE PLASTICS MATERIAL SACHET (71) We, MINNESOTA MINING AND MANUFACTURING COMPANY, a corporation organised and existing under the laws of the State of Delaware, United States of America, of 3M Center, Saint Paul, Minnesota 55101, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to flexible plastics material sachets for use in, for example, the storage and preservation of medical samples.

When doctors take biopsy tissue samples, the samples have to be immersed in a preservative until they reach the testing laboratory. Normally the preservative is a formalin solution and the doctor will add some of this and the sample to a glass vial or other container.

Formalin is highly toxic, however, and the exposure of the doctor to formalin fumes is highly undesirable. Also spills of formalin solution will accidentally occur from time to time and these are clearly undesirable.

It is therefore an object of the invention to provide a sachet which has amongst its uses that of storing and/or preserving biopsy tissue samples without danger to the doctor from the preservative.

According to the invention there is provided a flexible plastics material sachet having a plurality of compartments including two compartments separated from one another by a burstable seal which can be ruptured when required by exerting pressure on one or other of the said two compartments so as to provide communication between the said two compartments without destroying their seal with the outside, at least one of said two compartments having in its wall a slit through which items can be inserted to within that compartment, the slit being capable of being dosed and sealed by means of a pressure sensitive adhesive flap or tape.

Using such a sachet the doctor need never come in contact with toxic preservative fluids such as formalin. Thus the sachet can be prepared with preservative sealed into one of the compartments and then into the other compartment the doctor inserts the sample through the slit in the wall and seals the slit by the adhesive flap or tape.

Thereafter he can contact the sample with the preservative simply by bursting the burstable seal yet the sachet as a whole will remain sealed to the outside so that there can be no loss or spillage of the preservative.

The sachets according to the invention have as an important advantage the fact that they can be relatively small and inexpensive since they use only a small amount of material and so for the purpose noted above they are very convenient for a doctor to carry about with him when he visits a patient at home. Also they offer a great saving in storage space as compared with plastics bottles containing samples and they can readily be stored or mailed.

The sachets can be made from a transparent plastics material or alternatively an opaque plastics material if light sensitive samples are to be preserved.

Also the sachets can be used generally in the treatment of a variety of samples with predetermined fluids which can if required be accurately metered amounts of such fluids. The sachets of the invention can, however, have numerous other uses besides those noted above, of which examples are the dying of microscope specimens where the dye needs to be kept confined, in tissue culture, e.g. where one compartment can contain a nutrient broth while the tissue is inserted into the other compartment, that compartment sealed and then the tissue immersed in the broth, the dissolution of small solid samples in a controlled environment, the provision of limit-doses of treating materials to be mixed with a liquid or solid sample added through the slit, and in soil testing kits.

Flexible plastics material sachets divided into two or more compartments in turn separated by burstable seals are very well known and are described for example, in United States Patent Specifications Nos.

1,932,385 and 3,074,544. They generally comprise two sheets which have been heat sealed to one another round their edges to define the sachet. Each sheet is usually a laminate of a polyethylene layer to improve heat sealability and a polyester layer to impart dimensional stability. Before finally closing the compartments they can be filled and conventional sachets often contain two reactive components which are kept in separate compartments until immediately before use when the burstable seal separating the two compartments is broken to allow intimate mixing of the two components without use of separate containers followed by cutting open the sachet to dispense the mixed components.

The sachets according to the invention are characterised in that in at least one of the compartments there is provided a slit in a wall to enable a user to add something to that compartment. The slit can be formed by cutting with a knife edge and when the slit is later sealed by means of the length of adhesive tape or the adhesive flap there is therefore only a negligible area of the adhesive left exposed to the contents of the sachet. This greatly simplifies the closure and it appears that any tape or flap with an impermeable backing, i.e. a plastics material backing such as a vinyl polymer (e.g. polyvinyl chloride), as opposed to a paper backing, and an adhesive layer which will act as a pressure sensitive adhesive on the outer surface of the plastics material of the sachet is suitable.Many suitable pressure sensitive adhesive tapes are marketed and amongst them are those which we market under the Trade Name "Write-on" which are very suitable.

In order to reduce the risk of tearing the ends of the slit during the addition of a sample, the ends of the slit may have an enlarged rounded shape so that the slit resembles an elongated dumbell. Also the rounded ends of the slit can have a reinforcement such as a pressure sensitive adhesive plastics tape, which may be fibre-reinforced. This risk of tearing is most likely with sachets of larger size.

A separated length of adhesive tape may be used to seal the slit but preferably a length of tape is pre-struck to the material of the sachet along one side of the slit leaving the other part of the tape as a flap whose adhesive surface is covered by a release sheet. Then after insertion of a sample through the slits, the release sheet can be removed and the adhesive tape stuck down over the slit to close that compartment. It is advantageous for the backing of the adhesive tape to havea write-on surface so that the doctor can add identifying information to the sachet when as he has closed it, although this write-on ability can be provided elsewhere on the sachet.

The size, shape of the sachet and the number of compartments, the number of slits and the number of burstable seals in a sachet will be chosen depending upon the intended use of the sachet. A simple sachet for use by doctors as noted above will be rectangular, divided into two compartments by a burstable seal and the slit will be provided in one compartment. A conveninet size is about 2 inches by 4 inches with each compartment about 2 inches square. Instead, however, each compartment can have a slit, or there may be three or more compartments adjacent pairs of which are separated by burstable seals and one or more of these compartments can have slits for adding items.

The plastics material constituting the sachets of the invention will usually be a laminate of at least two sheets of plastics material rather than a single sheet because laminates can be given the desired physical properties of each layer so that one can combine excellent heat sealability as is required to give strong seals around the edge of the sachet with strength and/or low vapour transmission and/or inertness to the sachet contents. Polyethylene sheet have good heat sealability and low moisture vapour transmission and so they desirably constitute one layer of the laminate while polyester of polyamide sheets have high tensile strengths and so desirably constitute the other layer of the laminate.The exact choice of materials for each layer of the laminate will of course depend upon the precise intended use of the sachets so ensuring that the sachet is proof against leakage of gas or liquid contained therein and that the burstable seal will rupture well before the heat seals around the edges of the sachet.

The formalin solution or other liquid or aqueous preservative can be filled into one of the compartments and sealed therein in conventional fashion.

An example of a sachet according to the invention will be described with reference to the accompanying drawing which is a side view of the sachet.

The sachet 10 shown in the drawing has two compartments 12 and 14 separated from one another by a burstable seal 15 made in conventional fashion. The sachet has been made from two pieces of laminated plastics material whose edges have been heat sealed to one another by side seals 16, a bottom seal 18, and a top seal 20. The sachet 10 can therefore largely be made in conventional fashion from conventional materials. One suitable laminate consists of a layer of polyethylene and a layer of polyamide.

The compartment 12 contains a preservative liquid such as formalin which has been filled into the compartment 12 before the sachet was finally closed by the top seal 20, which also closes the top of the compartment 14.

In the wall of the compartment 14 is a slit 22 having rounded edges 24 to assist in resisting tearing. a length of pressure sensitive adhesive tape 26 whose outer exposed surface has a write-on surface is adhered to the wall of the compartment 14 over the region shown cross-hatched. The length of tape 26 extends upwardly beyond the slit 22 to form a flap, this portion of the pressure sensitive adhesive tape being covered by a release sheet.

When a biopsy sample is taken, the doctor inserts the sample through the slit 22.

He next removes the release sheet and sticks the remainder of the tape 26 down so completely sealing the slit 22. Then he squeezes the compartment 12 to cause the seal 15 to burst so bringing the sample and the preservative liquid into contact with one another without himself being exposed to the preservative. If required he can write patient identification data on the backing of the adhesive tape 26 or one some other area of the sachet 10 which has a write-on surface.

WHAT WE CLAIM IS: 1. A flexible plastics material sachet having a plurality of compartments including two compartments separated from one another by a burstable seal which can be ruptured when required by exerting pressure on one or other of the said two compartments so as to provide communication between the said two compartments without destroying their seal with the outside, at least one of the said two compartments having in its wall a slit through which items can be inserted to within that compartment, the slit being capable of being closed and sealed by means of a pressure sensitive adhesive flap or tape.

2. A sachet as claimed in Claim 1 in which one of the said two compartments has a slit in its wall and the other of the said two compartments contains a preservative fluid.

3. A sachet as claimed in Claim 1 or Claim 2 in which the ends of the slit are rounded so that the slit resembles an elongated dumbell.

4. A sachet as claimed in Claim 3 in which the rounded ends of the slit have been reinforced.

5. A sachet as claimed in any preceding claim in which an edge portion of a length of pressure sensitive adhesive tape has been adhered to the material of the sachet along one side of the slit so as to leave a remaining portion of the tape as a flap for closing the slit, the adhesive of that remaining portion being covered by a release sheet.

6. A flexible plastics material sachet substantially as herein described and shown in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. preservative liquid such as formalin which has been filled into the compartment 12 before the sachet was finally closed by the top seal 20, which also closes the top of the compartment 14. In the wall of the compartment 14 is a slit 22 having rounded edges 24 to assist in resisting tearing. a length of pressure sensitive adhesive tape 26 whose outer exposed surface has a write-on surface is adhered to the wall of the compartment 14 over the region shown cross-hatched. The length of tape 26 extends upwardly beyond the slit 22 to form a flap, this portion of the pressure sensitive adhesive tape being covered by a release sheet. When a biopsy sample is taken, the doctor inserts the sample through the slit 22. He next removes the release sheet and sticks the remainder of the tape 26 down so completely sealing the slit 22. Then he squeezes the compartment 12 to cause the seal 15 to burst so bringing the sample and the preservative liquid into contact with one another without himself being exposed to the preservative. If required he can write patient identification data on the backing of the adhesive tape 26 or one some other area of the sachet 10 which has a write-on surface. WHAT WE CLAIM IS:

1. A flexible plastics material sachet having a plurality of compartments including two compartments separated from one another by a burstable seal which can be ruptured when required by exerting pressure on one or other of the said two compartments so as to provide communication between the said two compartments without destroying their seal with the outside, at least one of the said two compartments having in its wall a slit through which items can be inserted to within that compartment, the slit being capable of being closed and sealed by means of a pressure sensitive adhesive flap or tape.

2. A sachet as claimed in Claim 1 in which one of the said two compartments has a slit in its wall and the other of the said two compartments contains a preservative fluid.

3. A sachet as claimed in Claim 1 or Claim 2 in which the ends of the slit are rounded so that the slit resembles an elongated dumbell.

4. A sachet as claimed in Claim 3 in which the rounded ends of the slit have been reinforced.

5. A sachet as claimed in any preceding claim in which an edge portion of a length of pressure sensitive adhesive tape has been adhered to the material of the sachet along one side of the slit so as to leave a remaining portion of the tape as a flap for closing the slit, the adhesive of that remaining portion being covered by a release sheet.

6. A flexible plastics material sachet substantially as herein described and shown in the accompanying drawing.