Title of Invention	"A PLASTIC CORNER"
Abstract	A plastic container comprising a receptacle (1) and lid (6), the receptacle having a rim (2) projecting inwardly from adjacent walling and the lid (6) being a press fit into the rim (2), wherein the rim (2) of the., receptacle (1) has an upstanding first flange "(21)' forming the inner limb of a first upwardly-open channel (22) between whose outer limb (23) and the walling of the receptacle laterally extends a second flange (24), and the periphery of the lid has an inner depending skirt (10) that closely co-operates with the inside .of the first flange (21), an undulating portion (16) outward of the skirt (10) forming two open channels, namely a downwardly-open channel (14) which receives the first flange (21) and a second upwardly-open channel (16) which seats sealingly within the first upwardly-open channel (22), and an outer flange (18) that overlies the second flange {24), characterized in that the inner and outer sides of the first upwardly-open channel (22) flow from the base of the channel respectively inwardly and outwardly of the receptacle so that the second upwardly-open channel, whose underside is of complementary shape, wedges therein to provide a sealing function, while a projection (11) at the base of the skirt (10) has snap engagement under the first upwardly-open channel as sealing is effected to provide a retaining function.

Title of Invention

"A PLASTIC CORNER"

Abstract

A plastic container comprising a receptacle (1) and lid (6), the receptacle having a rim (2) projecting inwardly from adjacent walling and the lid (6) being a press fit into the rim (2), wherein the rim (2) of the., receptacle (1) has an upstanding first flange "(21)' forming the inner limb of a first upwardly-open channel (22) between whose outer limb (23) and the walling of the receptacle laterally extends a second flange (24), and the periphery of the lid has an inner depending skirt (10) that closely co-operates with the inside .of the first flange (21), an undulating portion (16) outward of the skirt (10) forming two open channels, namely a downwardly-open channel (14) which receives the first flange (21) and a second upwardly-open channel (16) which seats sealingly within the first upwardly-open channel (22), and an outer flange (18) that overlies the second flange {24), characterized in that the inner and outer sides of the first upwardly-open channel (22) flow from the base of the channel respectively inwardly and outwardly of the receptacle so that the second upwardly-open channel, whose underside is of complementary shape, wedges therein to provide a sealing function, while a projection (11) at the base of the skirt (10) has snap engagement under the first upwardly-open channel as sealing is effected to provide a retaining function.

Full Text	1 Improvements relating to plastic containers This invention relates to plastic containers. There has been described in WO 97/19801 a method of forming a plastics container with a rim similar to that of a conventional paint tin by blow moulding. This has proved very effective. However as with most innovations, there can generally be improvement, and this invention is aimed at providing an improved sealing arrangement for the lid and at strengthening the rim structure. According to the present invention there is provided a container comprising a receptacle and lid, the receptacle having a rim projecting inwardly from adjacent walling and the lid being a press fit into the rim, wherein the rim of the receptacle has an upstanding first flange forming the inner limb of an upwardly open channel from whose outer limb laterally extends a second flange, and wherein the periphery of the lid has an inner portion that closely co-operates with the inside of the first flange, an intermediate portion separated from the first portion by a downwardly-open channel which receives the first flange while the intermediate portion seats sealingly within the upwardly open channel, and an outer portion that overlies the second flange. Preferably there will be a third flange upstanding from the periphery of the second flange. With the lid fitted to the receptacle a gap will be left between the outer edge of said outer portion and this third flange and a space between the underside of said outer portion and the second flange. 2 The third flange will provide a fulcrum for an implement such as a screwdriver to be inserted for levering off the lid. When the intermediate portion is seated in the upwardly open channel there will generally be sealing to both the inner and outer limbs of the channel. Also, at least one pair of the co-operating sides of the upwardly open channel and the intermediate portion of the periphery of the lid will advantageously have a rib on one side and a complementary groove in the other which will have snap engagement when the sealing is effected. Preferably, the inner portion of the lid has a projection on its outer side to snap engage under the rim as sealing is effected. This will be the main agency for retaining the lid, and although it might contribute some sealing, the main sealing zone will be elsewhere. The intermediate portion of the rim of the lid may be formed as an upwardly-open channel. This will allow it to be transversely compressed as it is urged into the upwardly-open channel of the receptacle rim, enhancing the seal. The upper edge portion of the first flange preferably seats snugly in the base of the downwardly open channel. While not being the primary seal, this arrangement can contribute a further sealed barrier. When the receptacle is completed by blow moulding to expand a tubular or cup-shaped portion depending from the rim to form the main body of the receptacle, the rim can be made as a box section. The expansion may commence at the 3 base of a downward extension of the rim, and this extension is preferably reinforced by ribs extending radially inwards from the outer wall of the box section. These ribs maintain dimensional stability. A shoulder created at the bottom of the extension by the blow moulding will provide the part of the rim under which the projection on the inner portion of the lid snaps when the lid is fitted. The under edges of the ribs can also serve as barriers to any excessive penetration of the box-section by the upper portion of the blown tubular or cup-shaped portion. Usually the ribs will span the entire box section, but that is not essential for their main function of maintaining dimensional stability. It is sometimes desirable to provide paint tins with handles, and these are generally simple semi-circular loops hinged to diametrically opposite points. When these are slightly below the rim, as is often the case in the USA, they are attached to bale lugs. The receptacle outlined above can be formed with opposed bale lugs for a strap handle. Each lug may be a downward extension of the outer wall off the box section. It can be internally strengthened by a downwardly enlarged rib whose upper part performs the reinforcing operation of the ribs already referred to and around whose lower part the expanded portion wraps. The main portion of each bale lug will be assimilated into the wall of the receptacle as the expanded portion is blown flush with its exterior surface, leaving a part projecting with which an end of the strap 4 handle can engage. For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a vertical section of a blow moulded plastics container, comprising a receptacle and a lid, shown in pre-fitting position, Figure 2 is a sectional detail of the rim of the lid, Figure 3 is a sectional detail of the rim of the receptacle, Figure 4 is an exterior view of part of the upper end of the receptacle showing a bale lug, and Figure 5 is a vertical section on the line V-V of Figure 4. Referring to Figure 1, a receptacle 1 is of generally cylindrical form with an inset, annularly grooved rim 2 to be described in more detail below. It is stretch blow moulded by the technique described in WO 97/19801 to have a base with an annular rib 3 encircling a slightly recessed central portion . 4. The cylindrical side of the receptacle is formed with vertical ribs 5, the plastics being indented into the receptacle, to improve rigidity. A lid 6 for this receptacle may be injection moulded as a generally flat disc 7 (very slightly dished in the example shown) with an upstanding annular rib 8 near its periphery and beyond that a profiled rim 9 that co-operates with the rim 2 whose shape is best seen in Figure 3. But referring first to Figure 2 and the rim 9, at the 5 periphery of the disc 7 there is a small step down and out to a depending skirt 10 with an annular projection 11 at its bottom edge, half arrowhead in cross-section. This forms a downwardly and outwardly facing chamfer and an upwardly facing shoulder that acts as a hook, as described below. The width of the hook may only be of the order of lmm, to allow snap release from the mould. The skirt 10 thickens outwardly at a step near the top and provides the inner limb 12 of an inverted annular channel with a narrow base 13 and a wider mouth 14. The outer limb 15 of this channel returns to about the mid-height the skirt 10 and also provides the inner limb of an upwardly open channel 16. The outer limb 17 of that terminates in an outwardly projecting flange 18 level with the top of the basel3. Both channels are slightly flared and on the inside of the limb 15, near the top, and on the outside of the limb 17, towards the bottom, there are shallow grooves 19 and 20 respectively. The rim 8 fits sealingly to the inner part of the rim 2 and its flange 18 overhangs a space in the rim 2 which enables the lid 6 to. be levered off using the extreme outer top edge of the rim 2 as a fulcrum. It is thus a container of the type commonly known as a paint tin. Referring to Figure 3, the rim 2 is of more complex, undulating shape than the conventional paint tin rim, offering two and possibly three or even four annular sealing zones and strong enough to sustain the stresses to which such a rim may be subjected. .In cross section, the rim 2 has, from the inside, an 6 upstanding flange 21 defining the inside of a U-shaped channel 22 whose outer side 23 is lower than the flange 21. A horizontal flange 24 projects outwardly from the side 23 from just below the latter' s smoothly rounded top 25 and a skirt 26 depends from its outer edge. At the top of the skirt 2 6 there is a shallow external annular groove 27 used in holding the preform during moulding. At the outer top corner of the flange 24 there is an outset and upstanding further flange 2 8 whose rounded top is just higher than the top of the flange 21. The flange 21 has a slight inward taper towards the top, and the channel 22 is slightly flared. On the outside of the flange 21, near its top, and on the inside of the side 23, also near its top, there are small annular ribs 29 and 30 respectively. They are small enough for the rim 2 to be snap-extracted without damage from the single mould part that forms the upper profile. It will be understood that the ribs 29 and 30 could be on the lid and the grooves 19 and 20 on the receptacle. At regular intervals around the rim 2 there are slim ribs 31 in planes radial to the axis of the receptacle. They are shown in cross hatching to distinguish them from the hollow space which occupies much of the rim and from the rest of the rim with which they are integrally moulded. The ribs 31 are generally of polygonal form, with two edges at right angles joined by the integral moulding respectively to the underside of the flange 24 and the inside of the skirt 26. Ignoring a small indent into the rounded top 25, a 7 third edge is concave, follows and joins to the side 23, and extends under the channel 22 to terminate at a short downward extension 32 of the side 21. Before blow moulding, the extension 32 continues down smoothly into the tube or cup-like structure 33 that is expanded from the broken line position to form the body of the receptacle. The under edge of each rib 31 is straight and extends inwardly from just above the bottom of the skirt 26 to the bottom of the extension 32. Initially, this edge is free, but the rib 31 provides a finger 34 which abuts the outside of the extension 32. The rim 2 is shown in Figure 3 after completion of the receptacle 1 where the tubular or cup-like part 33 of the preform has been urged by the blowing upwardly and outwardly to meet and weld to the lower edge of the skirt 26. Beyond the outer shoulder 35 thus created, and below the skirt 26, the plastics material presses against the inside of the cylindrical mould cavity into which that skirt snugly fits. There is therefore a substantially smooth exterior transition between the skirt 26 and the wall of the container. An inner shoulder 36 is also created at the junction of the extension 32 and the outwardly turned uppermost section 37 of the expanded structure 33. This section 37 comes up against the lower edges of the ribs 31, one minor function of which is to contribute some reinforcement to the rim. Another, more important one is to arrest the upward expansion of the section 37. Without these ribs, or with smaller ones not extending down so far, 8 as has previously been proposed, the hot malleable plastics can be blown upwardly too far towards the flange 2 4 thus failing to create a good box-section, which is the principal source -of strength of the rim 2. An even more important function of the ribs 31 is to give dimensional stability to the extension 32. When the structure 33 below it is hot enough to be blow-moulded, that extension is itself inevitably quite hot, and malleable to a certain extent. The blowing can deform it. But the presence of the fingers 34 of the ribs 31 prevents this, at least locally. The number of ribs 31 required will vary with the size of the container, but it is reckoned that eight will generally suffice for small containers, say of half-litre capacity, while sixteen might be advisable for large, five-litre-containers. When the lid 6 is fitted, the skirt 10 locates inside the flange 21, the flange 21 enters the channel 13,14, and the portion forming the channel 16 enters the channel 22. The channel shape allows the inner and outer limbs 15 and 17 to be squeezed together slightly, facilitating the ribs 29 and 30 snapping into the grooves 19 and 20. Simultaneously the projection 11 reaches the shoulder 36 and its hook snap engages under that. Also at the same time, the top of the flange 21 seats in the base 13 of the inverted channel of the lid 6. The flange 18 projects towards but does not reach the flange 28, and there is space beneath it into which the tip of a screwdriver can be inserted for levering the lid free, using the top of the flange 28 as a fulcrum. 9 This engagement gives two annular sealing zones in the regions of the ribs 29 and 30 and grooves 19 and 20, and another possible sealing zone between the top of the flange 21 and the channel base 13, although that is not necessarily relied on. There is a contribution to the retention of the lid by the ribs and grooves and the surfaces wedged together in their vicinity but the main retention is by the engagement of the projection 11 and shoulder 36. In other words, unlike any paint tins known to Applicants the sealing and the retention of the lid are separated. Release is unlikely to be as easy as with most paint tin-type containers, since there are four annular zones where the lid 6 engages the rim 2. Even if one or both of the ribs 29 and 30 were omitted, which is an.option, there would still be very firm lid retention. Figures 4 and 5 show how provision may be made for fitting a strap handle. At diametrically opposite positions the skirt 26 is extended downwards as a trapezoidal bale lug 40. Towards the lower end of this there is an external, downwardly open hood 41 with an aperture 42 central of a sloping step 43. Internally, each of a pair of diametrically opposite ribs 31 is downwardly enlarged as a rib 44 to support the lug 40 by its lower part and reinforce rim 2 by its upper part, in the manner of the ribs 21. It presents its hypotenuse to the tubular or cup-like part 33. When that is blown it will engage each rib 44 and wrap it around it before pressing outwardly against the inside of the lug 40 and moulding itself around the edges of the lug 10 to become flush with its outer surface. The lug 40 will effectively be assimilated into the wall of the receptacle, but the hood 41 will be left projecting. One hooked end of the handle (not shown}, which may be in the form of a stiff wire semi-circle, is entered through the aperture 42 and is caught by the hood 41. The other end is likewise engaged by the corresponding bale lug. 11 WE CLAIM 1. A plastic container comprising a receptacle (1) and lid (6) , the receptacle having a rim (2) projecting inwardly from adjacent walling and the lid (6) being a press fit into the rim (2), wherein the rim (2) of the receptacle (1) has an upstanding first flange (21) forming the inner limb of a first upwardly-open channel (22) between whose outer limb (23) and the walling of the receptacle laterally extends a second flange {24), and the periphery of the lid has an inner depending skirt (10) that closely co-operates with the inside of the first flange (21), an undulating portion (16) outward of the skirt (10) forming two open channels, namely a downwardly-open channel (14) which receives the first flange (21) and a second upwardly-open channel (16) which seats sealingly within the first upwardly- open channel (22), and an outer flange (18) that overlies the second flange (24), characterized in that the inner and outer sides of the first upwardly-open channel (22) flow from the base of the channel respectively inwardly and outwardly of the receptacle so that the second upwardly-open channel, whose underside is of complementary shape, wedges therein to provide a sealing function, while a projection (11) at the base of the skirt (10) has snap engagement under the first upwardly-open channel as sealing is effected to provide a retaining function. 2. A plastic container as claimed in Claim 1, wherein a third flange (28) is upstanding from the periphery of the second flange (24) and, with the lid (6) fitted to the 12 receptacle (1), a gap is left between the outer edge of said outer portion (18) and the third flange (28) and a space is left between the underside of said outer portion (18) and the second flange (24). 3. A plastic container as claimed in Claim 1 or 2, wherein, when the undulating portion (16) is seated in the first upwardly-open channel (22), there is sealing to the inner and outer limbs (21,23) of the channel (22). 4. A plastic container as claimed in Claim 3, wherein at least one pair of the co-operating sides of the first upwardly-open channel (22) and the undulating portion (16) of the periphery of the lid (6) has a rib (29,30) on one side and a complementary groove (19,20) in the other which have snap engagement when the sealing is effected. 5. A plastic container as claimed in any preceding claim, wherein the inner skirt (10) of the lid has a projection (11) on its outer side to snap engage under the rim (2) as sealing is effected. 6. A plastic container as claimed in any preceding claim, wherein the upper edge portion of the first flange (21) seats snugly in the base (13) of the downwardly-open channel (14) . 7. A plastic container as claimed in any preceding claim, wherein the receptacle (1) is completed by blow moulding to expand a tubular or cup-shaped portion (33) depending from the rim (2) to form the main body of the receptacle and to make the rim (2) a box section, the expansion commences at the base of a downward extension (32) of the rim (2), and this extension is reinforced by ribs (31) extending radially inwards from the outer wall (26) of the box section. 8. A plastic container as claimed in Claim 7, wherein a shoulder (36) is created at the bottom of the extension (32) by the blow moulding, and the inner skirt (10) of the lid has a projection (11) on its outer side to snap engage under the shoulder (36) as sealing is effected. 9. A plastic container as claimed in Claim 7 or 8, wherein the under edges of the ribs (31) serve as barriers to any excessive penetration of the box-section by the upper portion (37) of the blown tubular or cup-shaped portion (33). 10. A plastic container as claimed in Claim 7, 8 or 9, wherein the ribs (31) span the entire box section. 11. A plastic container as claimed in any one of Claims 7 to 10, wherein the receptacle (1) is formed with opposed bale lugs (40) for a strap handle, each lug (4 0) being a local downward extension of the outer wall (26) of the box section and being strengthened internally by a downwardly-enlarged rib (44) whose upper part performs the reinforcing function of the ribs (31) and around whose lower part the expanded portion (33) wraps. 12. A container as claimed in Claim 11, wherein the main portion of each bale lug (40) is assimilated into the wall of the receptacle as the expanded portion (33) is blown flush with its exterior surface, leaving a part (41) projecting with which an end of the strap handle can engage. A plastic container comprising a receptacle (1) and lid (6), the receptacle having a rim (2) projecting inwardly from adjacent walling and the lid (6) being a press fit into the rim (2), wherein the rim (2) of the., receptacle (1) has an upstanding first flange "(21)' forming the inner limb of a first upwardly-open channel (22) between whose outer limb (23) and the walling of the receptacle laterally extends a second flange (24), and the periphery of the lid has an inner depending skirt (10) that closely co-operates with the inside .of the first flange (21), an undulating portion (16) outward of the skirt (10) forming two open channels, namely a downwardly-open channel (14) which receives the first flange (21) and a second upwardly-open channel (16) which seats sealingly within the first upwardly-open channel (22), and an outer flange (18) that overlies the second flange {24), characterized in that the inner and outer sides of the first upwardly-open channel (22) flow from the base of the channel respectively inwardly and outwardly of the receptacle so that the second upwardly-open channel, whose underside is of complementary shape, wedges therein to provide a sealing function, while a projection (11) at the base of the skirt (10) has snap engagement under the first upwardly-open channel as sealing is effected to provide a retaining function.

Full Text

1
Improvements relating to plastic containers
This invention relates to plastic containers.
There has been described in WO 97/19801 a method of forming a plastics container with a rim similar to that of a conventional paint tin by blow moulding. This has proved very effective. However as with most innovations, there can generally be improvement, and this invention is aimed at providing an improved sealing arrangement for the lid and at strengthening the rim structure.
According to the present invention there is provided a container comprising a receptacle and lid, the receptacle having a rim projecting inwardly from adjacent walling and the lid being a press fit into the rim, wherein the rim of the receptacle has an upstanding first flange forming the inner limb of an upwardly open channel from whose outer limb laterally extends a second flange, and wherein the periphery of the lid has an inner portion that closely co-operates with the inside of the first flange, an intermediate portion separated from the first portion by a downwardly-open channel which receives the first flange while the intermediate portion seats sealingly within the upwardly open channel, and an outer portion that overlies the second flange.
Preferably there will be a third flange upstanding from the periphery of the second flange. With the lid fitted to the receptacle a gap will be left between the outer edge of said outer portion and this third flange and a space between the underside of said outer portion and the second flange.

2
The third flange will provide a fulcrum for an implement such as a screwdriver to be inserted for levering off the lid.
When the intermediate portion is seated in the upwardly open channel there will generally be sealing to both the inner and outer limbs of the channel. Also, at least one pair of the co-operating sides of the upwardly open channel and the intermediate portion of the periphery of the lid will advantageously have a rib on one side and a complementary groove in the other which will have snap engagement when the sealing is effected. Preferably, the inner portion of the lid has a projection on its outer side to snap engage under the rim as sealing is effected. This will be the main agency for retaining the lid, and although it might contribute some sealing, the main sealing zone will be elsewhere.
The intermediate portion of the rim of the lid may be formed as an upwardly-open channel. This will allow it to be transversely compressed as it is urged into the upwardly-open channel of the receptacle rim, enhancing the seal.
The upper edge portion of the first flange preferably seats snugly in the base of the downwardly open channel. While not being the primary seal, this arrangement can contribute a further sealed barrier.
When the receptacle is completed by blow moulding to expand a tubular or cup-shaped portion depending from the rim to form the main body of the receptacle, the rim can be made as a box section. The expansion may commence at the

3
base of a downward extension of the rim, and this extension is preferably reinforced by ribs extending radially inwards from the outer wall of the box section. These ribs maintain dimensional stability. A shoulder created at the bottom of the extension by the blow moulding will provide the part of the rim under which the projection on the inner portion of the lid snaps when the lid is fitted.
The under edges of the ribs can also serve as barriers to any excessive penetration of the box-section by the upper portion of the blown tubular or cup-shaped portion. Usually the ribs will span the entire box section, but that is not essential for their main function of maintaining dimensional stability.
It is sometimes desirable to provide paint tins with handles, and these are generally simple semi-circular loops hinged to diametrically opposite points. When these are slightly below the rim, as is often the case in the USA, they are attached to bale lugs.
The receptacle outlined above can be formed with opposed bale lugs for a strap handle. Each lug may be a downward extension of the outer wall off the box section. It can be internally strengthened by a downwardly enlarged rib whose upper part performs the reinforcing operation of the ribs already referred to and around whose lower part the expanded portion wraps. The main portion of each bale lug will be assimilated into the wall of the receptacle as the expanded portion is blown flush with its exterior surface, leaving a part projecting with which an end of the strap

4
handle can engage.
For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a vertical section of a blow moulded plastics container, comprising a receptacle and a lid, shown in pre-fitting position,
Figure 2 is a sectional detail of the rim of the lid,
Figure 3 is a sectional detail of the rim of the receptacle,
Figure 4 is an exterior view of part of the upper end of the receptacle showing a bale lug, and
Figure 5 is a vertical section on the line V-V of Figure 4.
Referring to Figure 1, a receptacle 1 is of generally cylindrical form with an inset, annularly grooved rim 2 to be described in more detail below. It is stretch blow moulded by the technique described in WO 97/19801 to have a base with an annular rib 3 encircling a slightly recessed central portion . 4. The cylindrical side of the receptacle is formed with vertical ribs 5, the plastics being indented into the receptacle, to improve rigidity.
A lid 6 for this receptacle may be injection moulded as a generally flat disc 7 (very slightly dished in the example shown) with an upstanding annular rib 8 near its periphery and beyond that a profiled rim 9 that co-operates with the rim 2 whose shape is best seen in Figure 3.
But referring first to Figure 2 and the rim 9, at the

5
periphery of the disc 7 there is a small step down and out to a depending skirt 10 with an annular projection 11 at its bottom edge, half arrowhead in cross-section. This forms a downwardly and outwardly facing chamfer and an upwardly facing shoulder that acts as a hook, as described below. The width of the hook may only be of the order of lmm, to allow snap release from the mould. The skirt 10 thickens outwardly at a step near the top and provides the inner limb 12 of an inverted annular channel with a narrow base 13 and a wider mouth 14. The outer limb 15 of this channel returns to about the mid-height the skirt 10 and also provides the inner limb of an upwardly open channel 16. The outer limb 17 of that terminates in an outwardly projecting flange 18 level with the top of the basel3. Both channels are slightly flared and on the inside of the limb 15, near the top, and on the outside of the limb 17, towards the bottom, there are shallow grooves 19 and 20 respectively. The rim 8 fits sealingly to the inner part of the rim 2 and its flange 18 overhangs a space in the rim 2 which enables the lid 6 to. be levered off using the extreme outer top edge of the rim 2 as a fulcrum. It is thus a container of the type commonly known as a paint tin.
Referring to Figure 3, the rim 2 is of more complex, undulating shape than the conventional paint tin rim, offering two and possibly three or even four annular sealing zones and strong enough to sustain the stresses to which such a rim may be subjected.
.In cross section, the rim 2 has, from the inside, an

6
upstanding flange 21 defining the inside of a U-shaped channel 22 whose outer side 23 is lower than the flange 21. A horizontal flange 24 projects outwardly from the side 23 from just below the latter' s smoothly rounded top 25 and a skirt 26 depends from its outer edge. At the top of the skirt 2 6 there is a shallow external annular groove 27 used in holding the preform during moulding. At the outer top corner of the flange 24 there is an outset and upstanding further flange 2 8 whose rounded top is just higher than the top of the flange 21.
The flange 21 has a slight inward taper towards the top, and the channel 22 is slightly flared. On the outside of the flange 21, near its top, and on the inside of the side 23, also near its top, there are small annular ribs 29 and 30 respectively. They are small enough for the rim 2 to be snap-extracted without damage from the single mould part that forms the upper profile.
It will be understood that the ribs 29 and 30 could be on the lid and the grooves 19 and 20 on the receptacle.
At regular intervals around the rim 2 there are slim ribs 31 in planes radial to the axis of the receptacle. They are shown in cross hatching to distinguish them from the hollow space which occupies much of the rim and from the rest of the rim with which they are integrally moulded. The ribs 31 are generally of polygonal form, with two edges at right angles joined by the integral moulding respectively to the underside of the flange 24 and the inside of the skirt 26. Ignoring a small indent into the rounded top 25, a

7
third edge is concave, follows and joins to the side 23, and extends under the channel 22 to terminate at a short downward extension 32 of the side 21. Before blow moulding, the extension 32 continues down smoothly into the tube or cup-like structure 33 that is expanded from the broken line position to form the body of the receptacle. The under edge of each rib 31 is straight and extends inwardly from just above the bottom of the skirt 26 to the bottom of the extension 32. Initially, this edge is free, but the rib 31 provides a finger 34 which abuts the outside of the extension 32.
The rim 2 is shown in Figure 3 after completion of the receptacle 1 where the tubular or cup-like part 33 of the preform has been urged by the blowing upwardly and outwardly to meet and weld to the lower edge of the skirt 26. Beyond the outer shoulder 35 thus created, and below the skirt 26, the plastics material presses against the inside of the cylindrical mould cavity into which that skirt snugly fits. There is therefore a substantially smooth exterior transition between the skirt 26 and the wall of the container. An inner shoulder 36 is also created at the junction of the extension 32 and the outwardly turned uppermost section 37 of the expanded structure 33. This section 37 comes up against the lower edges of the ribs 31, one minor function of which is to contribute some reinforcement to the rim. Another, more important one is to arrest the upward expansion of the section 37. Without these ribs, or with smaller ones not extending down so far,

8
as has previously been proposed, the hot malleable plastics can be blown upwardly too far towards the flange 2 4 thus failing to create a good box-section, which is the principal source -of strength of the rim 2. An even more important function of the ribs 31 is to give dimensional stability to the extension 32. When the structure 33 below it is hot enough to be blow-moulded, that extension is itself inevitably quite hot, and malleable to a certain extent. The blowing can deform it. But the presence of the fingers 34 of the ribs 31 prevents this, at least locally. The number of ribs 31 required will vary with the size of the container, but it is reckoned that eight will generally suffice for small containers, say of half-litre capacity, while sixteen might be advisable for large, five-litre-containers.
When the lid 6 is fitted, the skirt 10 locates inside the flange 21, the flange 21 enters the channel 13,14, and the portion forming the channel 16 enters the channel 22. The channel shape allows the inner and outer limbs 15 and 17 to be squeezed together slightly, facilitating the ribs 29 and 30 snapping into the grooves 19 and 20. Simultaneously the projection 11 reaches the shoulder 36 and its hook snap engages under that. Also at the same time, the top of the flange 21 seats in the base 13 of the inverted channel of the lid 6. The flange 18 projects towards but does not reach the flange 28, and there is space beneath it into which the tip of a screwdriver can be inserted for levering the lid free, using the top of the flange 28 as a fulcrum.

9
This engagement gives two annular sealing zones in the regions of the ribs 29 and 30 and grooves 19 and 20, and another possible sealing zone between the top of the flange 21 and the channel base 13, although that is not necessarily relied on. There is a contribution to the retention of the lid by the ribs and grooves and the surfaces wedged together in their vicinity but the main retention is by the engagement of the projection 11 and shoulder 36. In other words, unlike any paint tins known to Applicants the sealing and the retention of the lid are separated.
Release is unlikely to be as easy as with most paint tin-type containers, since there are four annular zones where the lid 6 engages the rim 2. Even if one or both of the ribs 29 and 30 were omitted, which is an.option, there would still be very firm lid retention.
Figures 4 and 5 show how provision may be made for fitting a strap handle. At diametrically opposite positions the skirt 26 is extended downwards as a trapezoidal bale lug 40. Towards the lower end of this there is an external, downwardly open hood 41 with an aperture 42 central of a sloping step 43. Internally, each of a pair of diametrically opposite ribs 31 is downwardly enlarged as a rib 44 to support the lug 40 by its lower part and reinforce rim 2 by its upper part, in the manner of the ribs 21. It presents its hypotenuse to the tubular or cup-like part 33. When that is blown it will engage each rib 44 and wrap it around it before pressing outwardly against the inside of the lug 40 and moulding itself around the edges of the lug

10
to become flush with its outer surface. The lug 40 will effectively be assimilated into the wall of the receptacle, but the hood 41 will be left projecting.
One hooked end of the handle (not shown}, which may be in the form of a stiff wire semi-circle, is entered through the aperture 42 and is caught by the hood 41. The other end is likewise engaged by the corresponding bale lug.

11
WE CLAIM
1. A plastic container comprising a receptacle (1)
and lid (6) , the receptacle having a rim (2) projecting
inwardly from adjacent walling and the lid (6) being a press
fit into the rim (2), wherein the rim (2) of the receptacle
(1) has an upstanding first flange (21) forming the inner
limb of a first upwardly-open channel (22) between whose
outer limb (23) and the walling of the receptacle laterally
extends a second flange {24), and the periphery of the lid
has an inner depending skirt (10) that closely co-operates
with the inside of the first flange (21), an undulating
portion (16) outward of the skirt (10) forming two open
channels, namely a downwardly-open channel (14) which
receives the first flange (21) and a second upwardly-open
channel (16) which seats sealingly within the first upwardly-
open channel (22), and an outer flange (18) that overlies the
second flange (24), characterized in that the inner and outer
sides of the first upwardly-open channel (22) flow from the
base of the channel respectively inwardly and outwardly of
the receptacle so that the second upwardly-open channel,
whose underside is of complementary shape, wedges therein to
provide a sealing function, while a projection (11) at the
base of the skirt (10) has snap engagement under the first
upwardly-open channel as sealing is effected to provide a
retaining function.
2. A plastic container as claimed in Claim 1, wherein
a third flange (28) is upstanding from the periphery of the
second flange (24) and, with the lid (6) fitted to the

12
receptacle (1), a gap is left between the outer edge of said outer portion (18) and the third flange (28) and a space is left between the underside of said outer portion (18) and the second flange (24).
3. A plastic container as claimed in Claim 1 or 2,
wherein, when the undulating portion (16) is seated in the
first upwardly-open channel (22), there is sealing to the
inner and outer limbs (21,23) of the channel (22).
4. A plastic container as claimed in Claim 3, wherein
at least one pair of the co-operating sides of the first
upwardly-open channel (22) and the undulating portion (16) of
the periphery of the lid (6) has a rib (29,30) on one side
and a complementary groove (19,20) in the other which have
snap engagement when the sealing is effected.
5. A plastic container as claimed in any preceding
claim, wherein the inner skirt (10) of the lid has a
projection (11) on its outer side to snap engage under the
rim (2) as sealing is effected.
6. A plastic container as claimed in any preceding
claim, wherein the upper edge portion of the first flange
(21) seats snugly in the base (13) of the downwardly-open channel (14) .
7. A plastic container as claimed in any preceding
claim, wherein the receptacle (1) is completed by blow
moulding to expand a tubular or cup-shaped portion (33)
depending from the rim (2) to form the main body of the
receptacle and to make the rim (2) a box section, the
expansion commences at the base of a downward extension (32)
of the rim (2), and this extension is reinforced by ribs (31)

extending radially inwards from the outer wall (26) of the box section.
8. A plastic container as claimed in Claim 7, wherein
a shoulder (36) is created at the bottom of the extension
(32) by the blow moulding, and the inner skirt (10) of the
lid has a projection (11) on its outer side to snap engage
under the shoulder (36) as sealing is effected.
9. A plastic container as claimed in Claim 7 or 8,
wherein the under edges of the ribs (31) serve as barriers to
any excessive penetration of the box-section by the upper
portion (37) of the blown tubular or cup-shaped portion (33).
10. A plastic container as claimed in Claim 7, 8 or 9,
wherein the ribs (31) span the entire box section.
11. A plastic container as claimed in any one of
Claims 7 to 10, wherein the receptacle (1) is formed with
opposed bale lugs (40) for a strap handle, each lug (4 0)
being a local downward extension of the outer wall (26) of
the box section and being strengthened internally by a
downwardly-enlarged rib (44) whose upper part performs the
reinforcing function of the ribs (31) and around whose lower
part the expanded portion (33) wraps.
12. A container as claimed in Claim 11, wherein the
main portion of each bale lug (40) is assimilated into the
wall of the receptacle as the expanded portion (33) is blown
flush with its exterior surface, leaving a part (41)
projecting with which an end of the strap handle can engage.

A plastic container comprising a receptacle (1) and lid (6), the receptacle having a rim (2) projecting inwardly from adjacent walling and the lid (6) being a press fit into the rim (2), wherein the rim (2) of the., receptacle (1) has an upstanding first flange "(21)' forming the inner limb of a first upwardly-open channel (22) between whose outer limb (23) and the walling of the receptacle laterally extends a second flange (24), and the periphery of the lid has an inner depending skirt (10) that closely co-operates with the inside .of the first flange (21), an undulating portion (16) outward of the skirt (10) forming two open channels, namely a downwardly-open channel (14) which receives the first flange (21) and a second upwardly-open channel (16) which seats sealingly within the first upwardly-open channel (22), and an outer flange (18) that overlies the second flange {24), characterized in that the inner and outer sides of the first upwardly-open channel (22) flow from the base of the channel respectively inwardly and outwardly of the receptacle so that the second upwardly-open channel, whose underside is of complementary shape, wedges therein to provide a sealing function, while a projection (11) at the base of the skirt (10) has snap engagement under the first upwardly-open channel as sealing is effected to provide a retaining function.

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Patent Number

206706

Indian Patent Application Number

IN/PCT/2001/00901/KOL

PG Journal Number

19/2007

Publication Date

11-May-2007

Grant Date

10-May-2007

Date of Filing

31-Aug-2001

Name of Patentee

PCC TECHNOLOGIES PLC

Applicant Address

28,HEREFORED ROAD. LONDON W25AJ,

Inventors:

#	Inventor's Name	Inventor's Address
1	BRITTON, CHARLES, JONATHON	6,ELMVILL ROAD,ASCHURCH,TEWKESBURY,GLOUCESTER SHIRE GL208DD,

PCT International Classification Number

B65D 43/06

PCT International Application Number

PCT/GB00/00283

PCT International Filing date

2000-02-02

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	9902244.4	1999-02-02	U.K.