GB2114955A - Container having an interfitting lid - Google Patents

Abstract

A container such as used for plant tissue culture for biological and chemical research purposes consists of an upwardly open base (34) having a wall (37) surmounted by an upwardly open channel (41) extending fully around the base (34) and a cover (27) having a dependent wall (29, 31, 32) terminating in a periphery (33) which is located within the channel (41) of the base (34) when the cover (27) is fitted on the base (34) and the container is therefore closed. Condensation which forms inside the cover (27) is thus directed to the channel (41) or falls directly from the cover (27) into the base (34). The inner side (38) of the channel, (41) is preferably lower than the top (42) of its outer side and if the channel (41) fills with condensation therefore the excess overflows the inner side (38) and returns to the base (34). <IMAGE>

Description

SPECIFICATION Container This invention relates to containers and is concerned in particular with containers of the kind comprising a base and an interfitting cover or lid.

Containers of this kind, typically made of clear transparent plastics material, are widely used in laboratories and other scientific establishments, for instance for plant tissue culture for biological and chemical research purposes.

A plant tissue culture container according to the prior art consists of a deep tray-like base, which is essentially square in plan and of a sufficient size and depth to contain a typical quantity of a growth medium. This container base, like the associated cover, is made by vacuumforming from clear plastics sheet material. In order to cooperate with the cover or lid and so close the container, the rim of the base includes a substantial dependent wall-like portion, having an outwardly-directed flange at the bottom. The outwardly-facing surface of this dependent wall and the adjacent upper surface parts of the rim of the base correspond to respective inwardly-facing and downwardly-facing surfaces of a rim structure provided on the cover of the container.Also, cooperating notches or indents are formed in the dependent wall portion of the base and the corresponding wall portion of the cover, so that the latter snaps into place and has to be positively removed from the base when the container is to be opened.

The cover is of a substantial height, being perhaps twice as tall as the base, in order to allow adequate headroom for the growth of plant tissue or other material propagated in the container on the growth medium contained in the base. The cover is also generally square in plan and its uppermost part is integrated with the rim portion previously mentioned by means of a sloping wall or web portion, thus forming a rounded edge which is lower than the remainder of the sloping wall or web. This edge is intended to ensure that any liquid, such as condensation, which collects on the inside of the cover will fail into the base.

However, these known tissue containers have a substantial degree of face-to-face contact between the interfitting surfaces of the rim parts of the base and the cover. Despite the lower edge in the cover being located inboard of the walls of the base, liquid can readily migrate between the contacting parts of the base and lid, for instance by capillary action and also by local condensation, so that undesirable leakage and also bacterial growth can take place, particularly if the containers are being used for experiments which extend over long periods of time. One purpose of the present invention is to improve such containers in various ways, but particularly with regard to simplicity of the interfitting arrangements between the covers and the bases.

The invention provides containers which also have other improvements, as will appear below.

According to this invention, the base includes a wall portion surmounted by a rim in the form of an upwardly-open channel, preferably of V-shape in section, and the cover includes a dependent rim portion which, with the container closed, is located in the channel. Preferably, the rim portion of the cover is a vertical wall terminating in a narrow outward roll or flange, which locates in or adjacent the lowest part of the channel, and the outer side of the latter also is vertical. Whether or not the cooperating parts of the cover and base have these latter features or instead are formed differently, face-to-face contact between the cooperating parts is avoided. In use, any condensation formed inside the cover may run into the channel in the base, where it can form a liquid seal for the container.Preferably, the inner side of the channel is lower than the outer, so that any excess liquid collecting in the channel returns to the base of the container, by flowing over the rim at this inner side. It is found in practice, especially with the cover having the preferred shape, that drops of liquid formed by condensation, provided it is not excessive, either drip from a ridge or edge incorporated in the cover so as to fall into the base or remain at the ridge or edge and eventually disappear by drying out. In either case, the liquid does not tend to collect in the channel in the base, but remains in the container, either by joining the solid and/or liquid materials in the base or by evaporating into the container atmosphere.

In order that the invention may be readily understood, a preferred embodiment of a container in accordance with the invention is described in detail below in conjunction with the accompanying drawings, which for comparison purposes also shows a typical plant tissue or like container of the kind already known and in use.In the accompanying drawings: Fig. 1 shows in vertical cross-section the interfitting cover and base of a known container according to the prior art; Figs. 2 and 3 are drawn to the same scale, larger than that of Fig. 1, in order to clarify illustration of the container of the invention, and show cross-sections through the cover and the base respectively of a container according to the invention; Fig. 4 shows a fragmentary perspective view of the base of a container according to the invention, in order to illustrate the interlocking arrangements provided in it for cooperation with the cover; Fig. 5 shows a fragmentary sectional view through the corner of the base on the line V-V of Fig. 4;; Fig. 6 shows diagrammatically containers according to the invention having similar bases and flat, normal and tall covers, respectively, so that growing plants of different heights can be accommodated; Fig. 7, shows a general perspective view of a preferred form of a container of the invention, in part broken away, in order to illustrate several additional preferred features of the invention; Fig. 8 shows a detail of the bases of containers of the invention whereby two or more can be joined together, for instance in order to maintain the same positions relative to one another during a period of use; Fig. 9 shows a perspective view of a tray-like holder for receiving a group of the containers of the invention, for facilitating handling of the containers.

Referring to Fig. 1, a container 10 according to the prior art consists of a one-piece base 11 and a one-piece cover 1 2. These two parts of the container 10 are made by vacuum-moulding from clear plastics sheet material and the container is generally square in plan, with rounded corners, the base 11 being nominally 10 cm x 10 cm with an overall depth of 7 cm, so that the closed container 10 has a height of approximately 9 cm. The traylike base 11 consists of a wall 1 3 upstanding from a floorlike base portion 14. At the upper edge of the wall 13, a narrow outwardly-directed flange 1 5 is provided which carries at its outer edge a dependent wall member 16, which is approximately 1 cm in height. At its lower edge, this wall member 16 terminates in an outwardlydirected flange 1 7.Each of the four parts of the wall member 16 corresponding to each part of the wall 1 3 of the base 11 includes a spaced pair of indents or notches 18 so that the base 11 has 8 of these notches 1 8 altogether. As explained below, these cooperate with similar notches formed in a corresponding part of the cover 1 2, in order to allow the two parts of the container 10 to lock together. The dependent wall member 1 6 has a slight upward taper, so as to facilitate engagement with and release from the cover 12. Also, the wall 13 has a slight downward taper, in order to facilitate release from the mould in which the base 11 is made.Preferably, at one corner of the base 1 the flange 1 7 is extended so as to provide a projecting triangular portion (not shown) which can be used to steady the base when the container 10 is being opened by removal of the cover 12.

The cover 12 consists of a generally square upper cover member 1 9 which merges into a deep dependent upwardly-tapering wall 20. At the lower edge, the wall 20 carries an upwardly and outwardly-directed flange or sloping wall member 21 which merges, at its upper edge, into an outwardly-directed flange member 22. When the base 11 and the cover 12 are fitted together, this member 22 overlies and contacts the narrow flange 1 5 in the base 11. At its outer rim, the horizontal flange 22 has a substantial dependent well member 23, which corresponds in shape and dimensions to the wall member 1 6 of the base 11 and, at its lower edge, has a small outwardlydirected roll or flange 24, corresponding to the base flange 1 7.Pairs of notches 25 are formed in the wall member 23 of the cover 12, in positions which correspond to those of the notches 1 8 in the wall member 16 of the base 1 1. A fragmentary cross-section through the part of the wall member 23 containing one of the notches 25 is shown in dotted lines at the right-hand side of Fig. 1.

As Fig. 1 shows, the junction between the dependent wall 20 and the sloping wall or flange 21, of the cover 12, represented by the edge 26, is the lowest part of the cover 1 2 within the base 11, when these two parts are interfitted and the closed container 10 is standing on a level surface.

This edge 26 is intended to ensure that condensation forming within the cover 1 2 will drip from the edge 26 and therefore within the confines of the base 11 and fall into the latter. In practice, however, condensation can take place in the tapering region between the flange or wall member 21 and the top of the wall 1 3 of the base 11 and can migrate into the substantial capillary region between the flanges 1 5 and 22, the dependent wall members 1 6 and 23 and the flanges 17 and 24.This region has a width of 1 cm or more, in a container 10 of the dimensions mentioned above, and a length equivalent to the entire girth of the container 10, namely approximately 40 cm, so that the closure formed by the base 11 and the cover 1 2 presents a substantial capillary width having an area of not less than 40 sq cm, which gives considerable scope for contamination of the adjacent parts of the container 10 both inside and outside.

In accordance with the invention, as illustrated in Figs. 2 to 5 of the drawing, a substantial capillary area formed by face-to-face contact between the base and cover of the container and located outside the lowest part of the cover within the base, when the container is closed, is avoided.

As shown in Fig. 2, the cover 27 of the container of the invention consists of a flat cover member 28, preferably rectangular in plan as is the cover and the base. At its edges, this cover member 28 merges via a downwardly-curving part into a downwardly widening wall portion 29. At its lower periphery 30, this wall portion 29 merges into a downwardly and outwardly-directed sloping wall part 31, which in turn carries a substantially vertical dependent web 32. This terminates at its lower periphery in a narrow outwardly-directed roll or flange 33.The lower periphery 30 is the location where, in practice, droplets formed by condensation in the cover 27 collect and either fall off or dry up. it can be seen from Figs. 2 and 3, in conjunction, that droplets which may form on the periphery 30 will fall into the base, described below, because the periphery 30 is located nearer the inside of the container than any wall part of the base.

The base of the container of the invention is shown at 34 in Fig. 3, in vertical cross-section similarly to the cover 27 shown in Fig. 2. The base 34 consists of a generally flat rectangular ba,se member 35 designed to support the container consisting of the cover 27 and the base 34 upon a level surface, such as that shown at 36. At its periphery, the base member 35 merges via an upwardly curved part into a slightly outwardly tapered wall member 37. At its upper edge, this wall member 37 turns outwardly in the form of a substantial rim 38, which in'turn carries an upwardly open V-section channel formation constituting the peripheral part of the base 34.

This channel formation in part consists, as shown, of an outwardly and downwardly-directed sloping flange 39. The flange 39 merges into an outwardly and upwardly-curved peripheral region 40, forming the bottom of the V-section channel formation, and from the region 40, the base 34 is completed by an upright wall portion 41, terminating at its upper extremity in a very narrow outwardly-directed roll or flange 42. When the cover 27 is fitted on to the base 34 of the container of the invention, as shown in broken lines in Fig. 3, the dependent web 32 and the outwardly-directed roll orflange 33 of the cover 27 lodge adjacent the peripheral region 40 in the V-section channel of the base 34 formed by the sloping flange 39 and the wall portion 41.

At each of the four corners of the container where the long or short sides merge and curve into one another, as shown in Fig. 4, inwardlydirected notches or detent members 43 are formed in the base 34. Each detent member 43 consists of an inward displacement of the wall portion 41 extending approximately over a quadrant, as best shown in Fig. 4. This detent member 43 is illustrated in vertical section in Fig.

5. The corner of the dependent web 32 and the flange 33 of the cover 27 are likewise curved.

These arrangements ensure that the cover 27 is firmly attached to the base 34, because these curved portions of the flange 33 snap below the detent members 43 and fit together so that the rim part of the cover 27 is wholly located within the V-section channel formation constituted by the wall 41 and the flange 39 of the base 34. Thus the container of the invention consisting of the cover 27 and the base 34 has an improved construction, completely avoiding any undesirable large area of capillary-like face-to-face surface portions. Also, the moulded components constituting the cover 27 and the base 34 are relatively simple to make, so that a container of the invention can be made more cheaply than a container of the kind illustrated in Fig. 1 of the drawing, for instance.

The containers of the invention can be moulded parts, as just indicated. However, a preferred method of manufacture of the bases and the covers is vacuum-forming from appropriate sheet plastics material and a preferred plastics material in polyvinyl chloride, i.e. pvc sheet. Other methods of manufacture can be used and also other materials, the main consideration being to avoid any n,dterial for manufacture which might be affected by the growth medium or other contents of the container or by the products of the propagation of specimens or, conversely, which might itself adversely affect the materials contained or formed in the containers. Methods of manufacture which can be used satisfactorily, instead of vacuum-forming, include injection moulding, blow moulding and rotational or slush moulding.Polystyrene can be used as the plastics material from which the containers are made, as it is highly adaptable to the various forming and moulding methods utilizable, but it is not a first preference, because some growth media or other materials which might be used in the containers can have an adverse effect on polystyrene and this material is preferably avoided, where this disadvantage is a possibility. Another plastics material, which is especially suitable if the containers are made by a moulding technique, is a polycarbonate. Containers so made are particularly durable and this is therefore a preferred choice if it is intended to make repeated use of the container.

The containers of the invention can be made for sale either in a sterile or a non-sterile condition.

They are conveniently packaged with a base nested in a cover, the latter being inverted as compared with its normal position of use when closing the container. This enables the container to be prepared for use, by standing it upon the top of the cover with the base loosely nested inside; the required materials can then be put into the base, which is then lifted out of the inverted cover, put into an incubator or on to a support for transfer to an incubator and then the cover is put into place and snapped down to close the container. The nested bases and containers can themselves be nested together for ease of packing, e.g. the bases and covers of 10 containers being put into a sleeve-like box or other packaging container.If the containers are to be sold in a sterile condition, this is most conveniently arranged by treating the formed or moulded containers with gamma-radiation, as the final manufacturing step prior to packaging.

The container of the invention is not limited to many of the features shown in Figs. 2 to 5 of the drawing. For instance, the container is preferably rectangular, as this appears to give good economy in use of the plastics material used to make the containers, but they can also be of other shapes, including square, circular, elliptical and hexagonal in plan. The channel formation can be different in cross-section from that described above, being for instance V-shaped as above, but with the inner wall vertical or with both walls at equal and opposite angles to the vertical. Considerable variation is possible, as will be readily understood.

Important "natures of the invention include the absence of substantial portions in close juxtaposition in the closed state, giving gaps of capillary size, formation of the base so that its outermost portion is also its highest portion and it totally encloses the outermost portion of the cover when the two are fitted together, formation of the cover so that all internal surfaces drain to its lowermost rim and the provision around the periphery of the base of a channel-formation capable of receiving the rim of the cover and forming a liquid seal around it.

The containers can of course be made in a wide variety of sizes, so as to have overall dimensions of, say, 12 cm length x 9.5 cm width x 9 cm height, so as to be suitable for instance for research laboratory use. Very different dimensions can be selected, of course, for instance 25 cm length x 20 cm width x 18 cm height, if the containers are to be used for instance for commercial propagation of plants.

As shown in Fig. 2, different lids can be supplied with standard bases, so that the containers can be used for the propagation of plants which are low, medium or tall in growth.

Fig. 6 shows 3 similar bases 45 A, 45 B and 45 C, the first being provided with a substantially flat cover 46 A, the second with a standard height cover 46 B and the third with a high cover 46 C.

Fig. 7 shows a container 50 comprising a base 51 and a cover 52, each made e.g. by vacuum forming from pvc sheet and having the shapes, relative dimensions and features described in relation to Figs. 2 to 5. The base 51 can be marketed with a growth medium, e.g. soil or agar, in it, as indicated by the chain-dotted line 53. Also, a line can be marked on the base 51 such as at the position of the line 53, to indicate the level which represents optimum filling of the base 51, e.g.

when a specified volume of growth medium has been put into it. The base 51 can also be provided with lines 54 crossing one another in the form of a reference grid, so that each square so delineated can receive one plant or a small container such as a test tube. The preferred rectangular shape facilitates reliable orientation of the container, when it is used to house a number of plants, for instance, 12 plants in 2 rows of 6 or 3 rows of 4.

In this way, the individual plants can be more reliably recorded by their positions on the grid reference formed by the lines 54, possibly in conjunction with an indicator 55 formed in the wall of the base 51, such as the figure "1" shown in Fig. 7, which can indicate that the plant specimen associated with the nearest unit in the grid is the first in the number set out in rows in the container 50. The cover 52 can also include an indicator 56, such as an impressed trademark, to denote the front of the cover 52 and provide a means for instance in association with the indicator 55, for ensuring that the cover 52 is always replaced on the base 51 the same way round.The cover 52 may also be provided with ventilation means for the container 50. For instance, the top of the cover 52 can include one or more holes, such as shown at 57, which are closed or plugged, e.g. with a small piece of cotton-wool or wadding 58, allowing air or other gas to pass into or out of the container 50 as required, without producing any undue risk of contamination. Alternatively, a pointed tube such as shown at 59, provided with a similar cottonwool or other closure or plug 60 can be provided, either being lodged in an aperture in the cover 52 on manufacture, such as the hole 57, or being provided loosely in conjunction with the containers 50, when first sold, the covers 52 being free from such apertures.This enables the user to provide ventilation as and when required, by using one or more of the cotton-wool plugged tubes 59 to punch holes in the cover 52, such as indicated by the arrow at 61, so that the tube 59 lodges tightly in the hole it produces.

Fig. 8 shows a detail of a modification, whereby the containers, e.g. the bases for them, are provided with projecting flanges 62 extending at 1 or more corners, carrying means to allow the containers to be detachably joined together. Such means can consist for example of spaced pairs of male members on, say, two adjacent sides of each container base, with cooperating spaced pairs of female members on the other two sides. Two or more containers can be joined together by interlocking their respective male and female members. Alternatively, as illustrated in Fig. 8, the means may take the form of a suitable universal interlocking device provided at each corner of each container.The flanges 62 of two containers shown fragmentarily in Fig. 8 each contain a dependent tapered hollow tubular peg 63, which can fit into any other similar peg 63 on another container, as indicated by the arrow 64. Such means assist in stabilizing a group of containers, for instance, when they are located upon a support, such as a seed tray for carrying purposes or to facilitate installation into and removal from an incubator.

Another means for the same purposes is shown in Fig. 9 in fragmentary perspective view. This consists of a tray 65 having an array of apertures 66, each designed to hold one container, such as shown at 67. The tray 65 can be easily used to hold and transport a number of containers and also will maintain them in the desired configuration throughout the duration of an experiment. The tray 65 is conveniently provided with supporting feet, such as shown at 68, or like means, so that a loaded tray 65 can rest on the feet 68 e.g. on a bench surface, while being loaded with containers or while work is carried out on the latter.

The invention provides a considerably improved form of container of the kind referred to, which can include any of a wide variety of useful features of shape and construction.

Claims (23)

1. A container in the form of a base and a cover, each of the base and the cover comprising a onepiece component, wherein the base includes a wall portion surmounted by an upwardiy-open channel and the cover includes a dependent wall portion having a periphery which, when the container is closed by fitting the cover on to the base, is located within the channel of the base.

2. A container according to claim 1 , wherein the channel is V-shaped in section.

3. A container according to claim 1 or 3, wherein the top of the inner side of the channel is lower than the top of its outer side, whereby, if sufficient liquid runs off the cover to fill the channel, further liquid flows over the inner side of the channel into the base.

4. A container according to claim 1 or 2, wherein the outermost part of the dependent wall portion of the cover is also the lowermost part of the cover.

5. A container according to claim 4, wherein a dependent wall part of the cover merges at its lower periphery into a downwardly and outwardlydirected sloping wall part, whereby droplets formed by condensation within the closed container fall into the base from the lower periphery or dry up by evaporating into the container atmosphere.

6. A container according to claim 5, wherein the wall portion of the cover comprises a substantially vertical dependent web carrying an outwardly-directed roll or flange, which is located within the channel when the container is closed, whereby no part of the base is located in face-toface contact with any part of the cover.

7. A container according to any preceding claim, wherein inwardly-directed detent members are provided at spaced locations in the outer side of the channel and the periphery of the dependent wall portion of the cover snaps below the detent members, when the container is closed.

8. A container according to any preceding claim, wherein the base and the cover are substantially rectangular in plan.

9. A container according to claims 7 and 8, wherein a detent member is provided at each of the corners of the container base.

10. A contgaineraccording to any of claims 7 to 9, wherein each detent member consists of an inwardly displaced part of the outer side of the channel of the base part.

11. A container according to any preceding claim, wherein each of the base and the cover is moulded from a plastics material.

12. A container according to claim 11, wherein each of the base and the cover is a one-piece component made from a sheet plastics material by vacuum forming.

13. A container according to claim 11 or 12, wherein the plastics material is selected from polyvinyl chloride, polystyrene or polycarbonate.

14. A container according to any preceding claim, which comprises a base and two or more interchangeable covers of different heights.

15. A container according to any preceding claim, wherein the base incorporates sets of lines forming a reference grid which divides the bottom into a plurality of areas.

1 6. A container according to any preceding claim, wherein an indicator is formed in the wall portion of the base, for facilitating the correct location of a plurality of plant specimens in the container.

1 7. A container according to any preceding claim, having ventilation means provided in the cover or provided for incorporation into the cover by the user.

18. A container according to claim 17, wherein the cover includes at least one aperture which is capable of being closed or is capable of being plugged so as to allow gas to pass into or out of the container.

1 9. A container according to claim 17, wherein a closable or pluggable pointed tube capable of forming a ventilation aperture in the cover is provided in a hole formed in the cover or is capable of piercing and lodging in a hole formed in the cover by the user by means of such pointed tube.

20. A container according to any preceding claim, wherein the base incorporates a flange extending outwardly form the wall portion at one or more locations, such flange carrying means for detachablyjoining together two or more of such containers.

21. A container according to any preceding claim, which is capable of location in any one of a plurality of reception apertures for such containers provided in a tray, whereby a plurality of the containers can be located in the tray for storage or transport without their covers or contents being disturbed.

22. A container according to claim 21, wherein each reception aperture supports a container by means of the channel surmounting the wall portion of its base and the tray incorporates supporting feet by which it can stand upon a bench surface.

23. A container according to claim 1, substantially as hereinbefore described with reference to Figs. 2 to 5, Fig. 6, Fig. 7, Fig. 8 or Fig.

9 of the accompanying drawings.