WO2012005683A1

WO2012005683A1 - Packaging container

Info

Publication number: WO2012005683A1
Application number: PCT/SE2011/050933
Authority: WO
Inventors: John Shand; Erik Svensson; Aldin Becirovic
Original assignee: Pakit International Trading Company Inc.
Priority date: 2010-07-08
Filing date: 2011-07-08
Publication date: 2012-01-12
Also published as: EP2590866A1; CN103328335A

Abstract

A packaging container (100, 200, 300) consists substantially of a cellulose fibre material made from stock and includes a tray and a lid. In a locking mechanism of the container a portion of one of said tray and lid is a male member (124, 224, 324, 424) and a portion of another one of said tray and lid is a female member (126, 226, 326, 426). The male member has a first surface (120', 121 '), and the female member has a second surface (104b', 105b'), said surfaces engage one another in the closed container and have an extension along at least a section of the circumference of the container. The locking mechanism satisfies one or both of the following conditions, namely a) that the intersection between I: the lines of intersection between said first and second fibre material surfaces and a first vertical plane, which is a radial plane and II: a vertical plane which is perpendicular to said first vertical plane, form a wedge angle (β), causing the fibre material surfaces of the male and female members to engage one another in the mode of a clutch coupling when contacted, and b) that the frictional drag between the surfaces of the male and female members in their closing positions is enhanced by a spring force and a normal force developed between the male and female members during the closing operation.

Description

PACKAGING CONTAINER

FIELD OF THE INVENTION

The present invention relates to a packaging container made of a cellulose fibre material, comprising a bottom part, in this context referred to as tray, and a top part, referred to as lid, said tray and lid provided with closure means including first closure means of a male rim portion of the tray and second closure means of a female rim portion of the lid cooperating with said first closure means when the packaging container is closed.

BACKGROUND OF THE INVENTION

WO 2006/057610 discloses a method and a machine for making fibre products from stock, preferably stock made from chemithermomechanical pulp (CTMP), although also other pulp than CTMP can be contemplated. According to this prior art, the machine comprises a set of male tools and a matching set of female tools, in which it is possible to manufacture moulded products of a fibre material which possesses some valuable features, amongst which may be mentioned a high tensile strength, a significant stiffness and bending resistance, good insulation properties, and, not least important, the products are made of a material which does make use of fossil raw materials. All these features are beneficial for some specific products in the packaging art, such as for packaging take-away fast food to be eaten hot, e.g. hamburgers, hot-dogs, fish-and-chips, kebab dishes, and the like. However, the prior art disclosed in said WO2006/057610 does not allow employment of moulds which have negative draft angles with respect to the direction of mould release. Therefore it is not possible to manufacture, by means of the equipment of the said prior art disclosure, moulded packaging containers with closure means of the snap-fit type, which are conventional in this specific field and no doubt are practical in many cases.

From this background it is a first objective of the present invention to provide a container which advantageously may be used for packaging food which is hot when the food is placed in the container and which may be maintained hot for a considerable period of time, such that the food will not be cooled down while it e.g. is taken home from a take-away bar or restaurant, which container is provided with closure means which are not of the snap-fit type or of other type requiring moulds having negative draft angles. It is in other words an objective to provide a packaging container which can be manufactured employing the above mentioned prior art. Further it is an objective of the invention to provide a packaging container with closure means which in most respects are at least as good as snap-fit type closure means and in some respects includes improvements over many conventional snap-fit type as well as other types of closure means. For example, it is an objective to provide closure means which are very tight and therefore has a favourable impact on the heat maintenance capacity of the container. In this connection should be mentioned that this effect can be achieved according to the invention without use of heat-sealing, adhesive tape sealing, gluing or the like.

BRIEF DISCLOSURE OF THE INVENTION

The above mentioned objectives of the invention, according to one aspect of the invention can be achieved therein that the invention is characterized by what is stated in the independent patent claim 1.

Further characteristic features of the invention are stated in the dependent claims and/or will be apparent from the following description of three illustrative embodiments with reference to the accompanying drawings, in which, in perspective views,

Fig. 1 shows a first embodiment of an assembled packaging container according to the invention,

Fig. 2 and Fig. 3 show a stack of trays and lids, respectively, (the lids upside down) of the types included in the packaging container shown in Fig. 1,

Fig. 4 shows an end part of a vertical, cross-sectional view along a longitudinal centre line IV-IV of the packaging container shown in Fig. 1,

Fig. 5 shows a second embodiment of a closed packaging container of the invention; a first type clamshell packaging container, in a view showing the hinge side, referred to as rear side, and one other side, referred to as left side,

Fig. 6 shows the rear side of the closed packaging container of Fig. 5,

Fig. 7 is a side view of the first type clamshell packaging container in its open state with the tray to the left and the lid to the right in the drawing,

Fig. 8 shows the same open container as Fig. 7 in a view obliquely from above, Fig. 9 is a cross-sectional view of the container of Figs 5-8 in a vertical symmetry plane as viewed obliquely from above, illustrating the final stage of a closing operation, Fig. 9A shows an encircled detail of Fig. 9 at larger scale,

Fig. 9B illustrates a mathematical model in the form of graph of a detail of the tray included in the locking mechanism which is shown also in Fig. 9A, Fig. 10 is a cross-sectional view of the closed container,

Fig. 11 is a cross-sectional view of the container of Figs. 5-10 showing the inside side of a corner of the closed container,

Fig. 12 is a cross-sectional view of a third embodiment of the invention; a second type clamshell container in a vertical symmetry plane of the container as closed,

Fig. 12A shows a detail of Fig. 12 at a larger scale,

Fig. 13 is a perspective view of a fourth embodiment of the invention; a third type clamshell container in its open state as viewed obliquely from above,

Fig. 14 is a top view of the container of Fig. 13,

Fig. 15 is a side view of the container of Fig. 13 and Fig. 14,

Fig. 15A is a side view of the container of Fig. 15, illustrating how the container members may be accommodated relative to one another in a manufacturing mold, Fig. 16 shows the closed container of Figs. 13-15 in a vertical, longitudinal cross sectional plane along a central symmetry line, and

Fig. 16A shows an encircled detail of Fig.16 at a larger scale.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, the packaging containers according to the first, second, third and fourth embodiments of the invention are generally designated 100, 200, 300, and 400, respectively. They consist of a cellulose fibre material and are manufactured from stock according to the prior art technique which is disclosed in the above mentioned

WO2006/057610, which means that the container parts, i.e. the lids and trays, do not have any negative draft angles with respect to the direction of mould release in connection with the manufacturing of the products. The thickness of all parts and details of the containers is in the order of 0.1 - 1.0 mm, but all details of the containers need not necessarily be, and in some case should not be, equally thick.

Now, with reference to Figs. 1-4, the assembled packaging container 100, Fig. 3, according to the first embodiment of the invention consists of a bottom part 101 and a top part 102, referred to as tray 101 and lid 102, respectively. In the premises where the packaging container is intended to be used, for example in a take-away bar or restaurant, the trays 101 and lids 102 may be stacked separately, Fig. 2, in dispensing devices which are not shown but which may be of a conventional or new, convenient type. The tray 101 has a basically flat bottom 103, two opposite, longitudinal and convexly curved side walls 104, two opposite, convexly curved end walls 105, and rounded wall corners 106. Each side wall 104, each end wall 105, and each wall corner 106 consists of two wall sections, namely a first wall section 104a and 105a and first corner section 106a, respectively, which extends from the bottom 103 to a shelf plane 107 which is parallel with the bottom 103 and is horizontal when the tray rests on a horizontal surface, and a second section 104b and 105b, and corner wall section 106b, which extends from said shelf plane 107 to a flange plane 108, which is defined by the upper, horizontal surface of a flange 110. (When using the terms horizontal and vertical in the following in this text, reference is made to a conceived horizontal bottom plane of the tray 101 as well as of the assembled container 100.) In the region of the shelf plane 107, the tray 101 has a circumferential shelf 109 which is flat. The upper surface of the shelf 109 coincides with and defines said shelf plane 107, and the upper surface of the flange 110 coincides with and defines said flange plane 108. The outer edge section 111 of the flange 110 is bent obliquely downwards. The first wall sections 104a and 105a, as well as the second wall sections 104b and 105b are inclined outwards, at angles a and β, which amount to about 21° and 18°. The angle a of about 21° is not a critical angle but is chosen to provide a sufficient rigidity to the tray 101, while the angle β = 18° is an angle which not only promotes rigidity of the second wall sections 104b, 105b but also serves as a suitable inclination of an inclined plane in the cone clutch forming part of the locking mechanism of the packaging container. In said cone clutch, the second wall sections 104b, 105b and second corner sections 106b, together with the shelf 109 define a truncated cone, forming a female member 126 of the cone clutch. Also the

circumferential flange 110, the considerable width of the flange 110, as well as the circumferential, obliquely directed edge section 111, form part of the locking mechanism therein that they contribute to a significant rigidity of the second wall sections 104b, 105b, which is important for the functioning of the locking mechanism, as will be described in the following. In said cone clutch, the outside surfaces 120' and 121 ' of the male member 124 and the inside surfaces 104b' and 105b' of the female member 126 contact one another under pressure in the mode characteristic for cone clutches in general. A specific feature of the cone clutch employed in the packaging container according to the first embodiment of the invention, however, is that the surfaces 120', 121 ' and 104b ',105b' which are in contact with one another under pressure, expose a cellulose fibre material. When these surfaces are pressed together, fibres from the two engaging materials inevitably interact with one another at least physically. This is believed significantly enhances the frictional drag between the contacting packaging materials of the invention as compared with most other packaging materials. It is possible to promote this effect still further by intentionally making the interacting surfaces of the locking mechanism rougher that the rest of the product. A conceived developed embodiment of the invention employs this feature. What is meant with inclined plane angle or inclination of cone clutch surface angle β should be readily understood, as far as the specific example is concerned, which is described with reference to Fig. 4. In general terms, the angle β is defined as the angle between on one hand the lines 127 of intersection between the fibre material surfaces 120', 12 Γ; 104b ',105b' of the male and female members 124, 126 which contact one another, and a first vertical plane, which is a radial plane, and on the other hand a vertical plane 128 which is perpendicular to said first plane. The lid 102 has a central panel 115, two opposite, longitudinal and convexly curved inner side walls 116, two opposite and convexly curved inner end walls 117, rounded inner wall corners 118, and a circumferential base 119 which is horizontally directed outwards and integrally connected to the lower end of the side walls 116 and end walls 117. The width of the bottom of said base 119 corresponds to the width of the shelf 109 of the tray 101. Further, the lid 102 has two opposite, longitudinal and convexly curved outer side walls 120, two opposite and convexly curved outer end walls 121 and rounded outer wall corners 122. The said outer side and end walls 120, 121 and rounded outer corner walls 122 are integrally connected to the base 119 at the periphery thereof and are inclined upwards-outwards, forming an angle to a vertical plane equal with the inclination angle β of the second end wall sections 104b, 105b and second corner section 106b or - preferably - slightly larger than inclination angle β before the lid 102 has been attached into locking connection with the tray 101. The length of each of said outer walls 120, 121 and 122 equals the corresponding length of said second wall sections 104b, 105b and 106b of the tray in any radial, vertical plane through the packaging container. The said outer walls 120, 121 and 122 of lid 102 also, like the second wall sections 104b, 105b and 106b of tray 101, define a truncated cone, which matches the truncated cone of the tray 101 in the assembled packaging container, Fig. 3 and Fig. 4. The lid 102 is also, like the tray 101, provided with a flat, circumferential flange 123 which is integrally connected to the upper end of the said outer walls 120, 121 and 122. The flange 123 of the lid 102 contacts the flange 110 of the tray when the container is assembled. The radial width of flange 123 is smaller than the corresponding width of flange 110 of the tray, contributing to make the locking member assembly of the tray 101 stiff er than the locking member assembly of the lid 102. The flange 123 of the lid 102 has a protrusion 125 on each end of the container, serving as handle. The inner side and end walls 116, 117, the base 119, and the outer side and end walls 120, 121 in combination form a male member, generally designated 124, Fig. 4, which in cross-section has the shape of a blunt wedge. When closing the packaging container

100, the male member 124 of the lid 102 is pressed down into the female member 126 of tray 101, so far that the base 119 of the lid 102 contacts the shelf 109 and the flange

123 of the lid 102 contacts the flange 110 of the tray, respectively. As mentioned in the foregoing, the inclination angle of the outer side of said wedge-like male member 124 of the lid 102 conveniently is somewhat larger than the inclination angle β of the female member (the circumferential second wall sections 104b- 106b) of the tray 101 causing the outer side walls 120-122 of the lid 102 to be successively pressed against the successively matching wall sections 104b- 106b until the base 119 of the male member contacts the shelf 109 of the tray 101, causing a cone clutch connection between the lid 102 and the tray 101. Further, the lid 102 is larger than the tray 101 in the horizontal direction in the region of the interacting male and female members, which also promotes a cone clutch connection between the lid 102 and the tray 101.

Thus, as the male member is moved into the female member, the outer walls 120-122 of the male member are slightly deflected by the stiffer peripheral assembly 104b- 106b, 110, 111 of the tray 101, which works as a counter force, a dolly, against the male members, such that the outer walls 120-122, when the base 119 contacts the shelf 109, will snug fit under some pressure against said second wall sections 104b- 106b of the tray 101. The size of deflection partly depends on the manufacturing accuracy of the packaging container parts but is controlled by empirically based choice of the inclination angles of the conical surfaces that shall face one another in the closed container. Normally, the deflection may amount to between 0.5 - 1.0 times the thickness of the walls 120-122 of the male member of the lid 102. The snug fit that is achieved, whether or not depending on deflection, also means that the outer fibre material surfaces of the conical outer walls 120-122 of the lid 102 are in very efficient contact with the facing fibre material surfaces of the conical walls 104b- 106b of the tray

101, wherein the high friction properties of the cellulose material in the contacting surfaces of said conical walls are efficiently made the most of.

In the locking mechanism of packaging container according to the first embodiment, there is therefore achieved a cone clutch engagement between the cellulose fibre surfaces of male and female members in combination with frictional drag, which is enhanced by the spring and normal forces developed between the deflected male and the holding-up female member, the latter having a pronounced stiffness. As a result, there is provided an efficient closure of the package, however not stronger than the package readily can be opened by pulling, using the handles 125.

With reference now to Figs 5-10, the first type clamshell packaging container 200 according to the second embodiment of the invention consists of a tray 201 and a lid 202 connected to one another through a hinge 203. The hinge 203 is made in connection with the manufacturing of the container in a mould, in which the stock is compressed more strongly between the hinge forming parts of mould tools than between the other parts of tools. The main parts of the tray 201 are a bottom panel 204, a rear wall 205, a front wall 206, left and a right hand side wall 207 and 208, respectively, and a circumferential rim 209.

The lid 202 correspondingly has a top panel 214, a rear wall 215, a front wall 216, a left and a right hand side wall 217 and 218, respectfully, and a circumferential rim 219.

The rim 209 of the tray 201 and the rim 219 of the lid 202 have four sections of different shapes along the periphery of the tray and lid, respectfully, namely

a first section 209a and 219a, respectfully, at the rear end of the container, a second and third section 209b and 209c, and 219b and 219c, in the corner between the rear and the left hand side of the container, and in the corner between the rear and the right hand side of the container respectfully, and a fourth section 209d and 219d along the rest of the periphery of the tray and of the lid, respectfully, i.e. along the left and right hand sides, the front side and the corners between the front side and left and right hand sides.

Now, first, the design of the fourth sections 209d and 219d of the rims 209 and 219 of the non-closed packaging container 200 shall be described with reference to Fig. 9A and Fig. 9B. In the region of the rim section 209d, the rim 209 forms the upper edge of the front and side walls 206, 207, 208. In cross section, it includes a first inner segment 209d' which is straight and may be defined as an extension of the side wall 206; a second inner segment 209" which is convexly bent and extends from the end of the first segment up to a vertex 209V; a first outer segment 209d" ', which also is convexly bent and extends from said vertex 209V to a point of inflection 2091; and a concave outermost edge 209d^IV'

The fourth rim section 219d of the lid 202 also has four segments of different design. A first segment 219d' is concave relative to the outside. Next comes a convex, second segment 219d" followed by a third segment 219d"' and an outermost edge portion 219d^IV , which have approximately the same configuration as the third segment 209d' " and outermost edge 209d^IV of the fourth rim section 209d of the rim 209. In the point P where the rim 219 of the lid and the rim 209 of the tray initially contact one another, Fig. 9A, the tangent to the rim 219 of the lid forms an angle δ to a vertical line in the same vertical sectional plane, while the tangent to the rim 209 forms an angle γ to said vertical line, which angle γ is larger than said angle β. The difference is not large in terms of degrees or minutes but nevertheless of significant importance for the functioning of the locking mechanism of this second embodiment of the invention.

Now, as far as the curvature of the convex bend is concerned, which bend extends from the end point 209E of the straight segment 209d' to the point of inflection 2091 , it can in mathematical terms be defined as a "spline", a term which in the computer science subfield of computer-aided design refers to a piecewise polynomial curve. In the present, specific case the spline, i.e. the curvature of the said bend is designed such that the fourth rim section 209d, when subjected to a force by the lid 219 in the point of contact P in the region of said first outer segment 209d' ", will be further bent and that the further bending of the rim 209d of the tray will take place in the region of the second, inner segment 209d".

Thus, the final phase of a locking operation is initiated when the inside surface of the lower end of said third segment 219" ' of the lid 202 contacts the outside surface of the upper end of said third segment 209" ' of the tray 201, Fig. 9A. In the graph shown in Fig. 9B, this point of contact is designated P. Now, as the lid 202 is pressed

downwards, the inside surface of said lower end of said third segment 219"' of the lid 202 will slide against the outside surface of the said third segment 209' " of the tray 201. This causes said third segment 209d" ' of the tray 201 to deflect inwards, said second segment 209d' ' to be further and successively increasingly bent, and the vertex 209V to tilt outwards, until, in the final stage of the locking operation, the inside surface of the second segment 219d" of the lid 202, which forms a female member 226 of the lid, is pressed against the outer surface of the second segment 209d' ' of the tray 201. Thus, when the edge portion 219d^IV of the lid 202 contacts the corresponding edge portion 209d^IV of the tray 201, the curvature of the surfaces of the second and third rim segments 209d" and 209d" ' of the tray 201 which face the second and third segments 219d' ' and 219d' " of the lid 202, also will match said last mentioned second and third segments 219d" and 219d' " of the lid 202. This also means that the said fourth section reached this situation, shown in Fig. 10, in which the male and female members 224, 226 are engaged with one another in a cone clutch like engagement, the pressure of the third segment 219d' " of the lid 202 against the matching third segment 209d" ' of the tray 201 - said second and third bent and/or deflected segments 209d" and 209d"' acting as a spring - is maintained, which in combination also with the friction properties of the material of the packaging container ensures an efficient frictional drag between the lid 202 and the tray 201 and hence a safe closure. Optional recesses 220 in the rim 209 of the tray may be provided for ventilation. The packaging container 300, a longitudinal cross section of which is shown in Fig.12, is a second type clamshell packaging according to a third embodiment of the invention. Where possible, the same vocabulary has been used in the description of container 300 as for container 200. Also the same reference numerals have been used but with the first digit 2 replaced by the first digit 3. Like container 200 according to the above described second embodiment, container 300 consists of a tray 301 and a lid 302 connected to one another through a hinge 303 of the same type as hinge 203; see foregoing description. Also, like in the second embodiment, the main parts of the tray 301 consist of a bottom panel 304, a rear wall 305, a front wall 306, a left and a right hand side wall 307 (not shown) and 308, respectively, and a circumferential rim 309. The lid 302

correspondingly has a top panel 314, a rear wall 315, a front wall 316, and a left and a right hand side wall 317 (not shown) and 318, respectfully, and a circumferential rim 319. Further, also in accordance with the foregoing second embodiment, the rims 309 and 319 have four sections of different shapes along the periphery of the container 300, namely

- a first section 309a and 319a, respectfully, at the rear of the container,

a second and third section 309b (not shown) and 309c (not shown), and 319b (not shown) and 319c, in the corners between the rear and the left and the right hand sides of the container, respectfully, and

a fourth section 309d and 319d along the rest of the periphery of the tray and of the lid, respectfully, i.e. along the left and right hand sides, the front side and the corners between the front side and the left and right hand sides.

The first, second and third sections 309a,319a; 309b, 319b; and 309d,319d of clam shall packaging are designed according to the same principles as according to the second embodiment and will therefore not be explained in any detail. It is, however, true that the container 300 as illustrated in the drawing in Fig. 12 is more flat than container 200, but also a more voluminous container can be contemplated, as is indicated through the line of dashes in Fig. 12, without departing from the principles of the invention according to this third embodiment.

Basically, the design of the fourth section 319d' of rim 319 of container 300 differs from that of fourth section 219d of rim 219 of container 200 in that said first, straight segment 319d' has an extended length, at least as long as the length of the third segment 319d' ".Said straight first segment 319d' of the lid 302 matches the first segment 309d' of the rim of the tray 301, which first tray rim segment 309d' forms an upper part of the straight front 306 and side walls 307, 308 of the tray 301, wherein said first segments 319d' and 309d' engage one another cone clutch- wise in the locked packaging container, Fig. 12.

The second segments 309d" and 319d" as well as the third segments 309d" ' and 319d' " are in principle designed as the corresponding segments of the container rims 209 and 219 of container 200. Also the procedure of engagement between these male and female members is performed in the same mode as has been described in the foregoing with reference to Fig. 9A and Fig. 9B. Therefore, this description of procedure will not be repeated here. Instead, reference is made to the previous description of procedure and to Fig. 12A, which illustrates the initiation of the final phase of the locking operation of the packaging container 300 in the central region of the front part of the container (the engagement of the two rims in said fourth rims section 309d and 319d starts adjacent to the second and third sections 319b and 319c and then proceeds successively towards the front part of the container, as is the case also in the second embodiment of the invention). As the lid 302 is pressed down against the tray 301, the third segment 309d' ' ' of the tray^'s rim section 309d is deflected inwards by the third segment 309d"' of the lids^'s fourth rim section 319d, causing increased bending of the intermediate second segment 309d' ' and tightening it in its capacity of a spring. Finally, when the edge portions 309d^IV and 319d^IV contact one another, also the first segment 309d' of the rim of the lid 309 contacts the corresponding segment 319 d' of the rim of the tray 301, i.e. also a cone clutch is established between these segments of the locking mechanism. Now, in the locking mechanism of the packaging container 300, there is achieved in combination, retainment of the lid 302 and the tray 301 in their locking engagement due to

a frictional drag between the third (outer) segments 309d' ' ' and 319d" Of the said fourth rim sections 309d and 319d of the tray and lid, respectively, which is enhanced by a spring force of the tightened rim segment 309d' " of the tray 301 acting on the inside surface of the corresponding segment 319d' " of the rim of the lid which acts as a dolly, developing a counter-force, and

a clutch coupling between the first (inner) segments 309d' and 319d' of same fourth rim sections 309d' " and 319d" ' .

Now, turning to the fourth embodiment of the invention, the packaging container 400, which is illustrated in Figs. 13-16A, is a third type clamshell packaging. Where possible, the same vocabulary has been used also for this embodiment as for containers 200 and 300. Also the same reference numerals have been used but with the first digit 2 and 3, respectively, replaced by the first digit 4. Like containers 200 and 300, container 400 consists of a tray 401 and a lid 402 connected to one another through a hinge 403 of the same type as hinges 203 and 303. The main parts of the tray 401 are a bottom panel 404, a rear wall 405, a front wall 406, a left hand side wall 407, a right hand side wall 408, and a circumferential rim 409. The lid 402 has a top panel 415 and a circumferential rim 419 and is in principle flat according to the embodiment, as distinguished from the lid 302 of the third embodiment of the invention (although convex type lids may be considered in connection with the fourth embodiment as well). Further, also in accordance with the foregoing second and third embodiments, the rims 409 and 419 have four sections of different shapes along the periphery of the container 300, namely

a first section 409a and 419a, respectively, at the rear, in the region of the hinge 403 of the container,

a second and a third section 409b, 409c, and 419b, 419c in the rear corners of the tray 401 and of the lid 402, respectively,

- a fourth section 409d and 419d, forming male 424 and female 426 locking

members, respectively, along the rest of the periphery of the tray and of the lid.

The fourth embodiment has many features in common with especially the second embodiment, which is described in the foregoing, but is distinguished from that embodiment particularly as far as the design of the fourth section 419d of the lid 402 is concerned. The difference is best understood by reference to Fig. 16 A. In that figure, the locking mechanism of the invention according to the embodiment is shown in cross section at an enlarged scale, illustrating the interaction between the rim section 419d of the lid 402 and the rim section 409d of the tray 401. The dashed line represents the shape of the rim section 409d in said fourth section prior to locking of the container and prior to engagement between the two lids. In the pre- locking, "free state" of the rim section 409d, it has four segments, namely a first, inner segment 409', which is an extension of the side wall 406 and is straight, a second segment 409" which is convexly bent and includes a vertex 409V, a third, outer segment 409d" 'which is straight and of short length, or consists of an inflection point or inflection region of infinitesimal length, and a fourth, outermost edge segment 409d^IV which is concave. The fourth rim section 419d of the lid correspondingly consists of four segments, namely a first straight, basically horizontal segment 419d' which also could be defined as an outer part of the top panel 415, a second, convex segment 419d" ', a third, outer segment 419d" ' which is straight or at least basically straight and of considerable length, and a fourth segment 419d^Ivwhich is concave. The third segment 409d" ' of the rim section 409d of the tray 402, in the pre-locking state of said rim section, forms an angle γ to a vertical line in the cross sectional plane of Fig. 16A, and the third segment 419d" ' of the fourth rim section 419d of the lid 402 forms an angle δ to the same vertical line.

The members of the locking mechanism assembly, which consists of the fourth rim sections 409d and 419d of the tray 401 and of lid the 402, respectively, in combination, have the following distinctive features:

In a vertical, longitudinal cross sectional plane along a central symmetry line of the closed container the third segment 419' " of the lid 419 is significantly longer than the third segment 409' " of the tray. Alternatively, this feature can be expressed in the following terms; namely that the vertical distance D419 from the first segment 419d' to the tip 430 of the fourth segment 419d^IV of the lid 402 in said cross sectional plane, is significantly longer than the vertical distance D409 from the vertex 409V to the tip 429 of the fourth segment 409d^IV of the tray 401. Preferably it is at least 60 % longer and suitably at least 80 % longer. In the disclosed embodiment, it is in the order of 100 % longer.

The angle δ as defined above is significantly smaller than the angle γ as defined above. Preferably the angle δ amounts to between 5° and 15°, while the angle γ amounts to between 20° and 40°. In the mould employed for the manufacturing of the packaging container of the invention, draft angles normally must not be smaller than 14°

The horizontal extension L419 of the fourth segment 419d^IV of rim section 419d of lid 402 is significantly longer than the horizontal extension L409 of the fourth segment 409d^IV of the tray 401, which provides a desired stiffness to the fourth section 419d against deflection in the horizontal direction. Preferably the fourth segment 419d^Ivof rim section 419d of lid 402 is in the order of twice as long or longer in the horizontal direction than the corresponding segment 409d of the tray 401.

Now therefore, in consideration of the above mentioned features of the members of the locking mechanism, the outer parts, i.e. the parts outside of the vertex 409V, of the fourth segment 409d of the tray, are deflected by the fourth segment 419d of the lid 402, as is illustrated in Fig. 16A, during the closing and locking operation. In the locking position, the very tip 429, which has an advantageously sharp edge, of the fourth segment 409d^IV of the tray 401 is pressed against the inside surface of the rim 419 of the lid by spring force developed by the rim of the tray 401 due to its deflection. In connection herewith, also the uneven structure of the inside surface of the rim 419 in the region of contact with the sharp edge of tip 429 of the fourth segment 409d^IV of the tray 401 is important for the achievement of an efficient locking grip between the two rims.

In a preferred aspect of the invention the packaging containers are manufactured according to a method described in document WO 2006/057610, said method for producing a fibre product (e.g. a container) from a stock solution substantially comprising the following steps:

-providing a first tool (not shown) that is permeable to air and water,

-providing a second tool and heating the second tool to a temperature of at least 220°C,

-providing a moulding tank and feeding stock to the moulding tank,

-immersing the first tool in the stock in the tank,

-forming an embryonic fibre product on the first tool by applying suction through the first tool,

-removing the first tool from the stock,

-bringing the first tool against the second tool such that the formed fibre product is sandwiched between the first and the second tool and heated by the second tool such that at least a part of the water in the formed fibre product is vaporized, and

-dewatering the formed fibre product until it has reached a dry solids content of at least 70% after which the fibre product is subjected to drying.

Preferably said first and second tools used for manufacturing the fibre products comprise particles that have been sintered together to form a porous body which is permeable to air and water. Now referring to Fig. 15A there is seen a side view of a clamshell type container illustrating how the container members (i.e. the tray 401 and the lid 402) may be accommodated relative to one another in a manufacturing mould used in a manufacturing process as described e.g. in prior art document WO 2006/057610.

A product (i.e. container 400) of clamshell type can be manufactured using a mould which during production accommodates both the tray 401 and the lid 402 in one plane, however which is designed to accommodate the tray 401 and the lid 402 respectively such that an angle ε is created between the tray and the lid, where such an angle ε is larger than 180°. For example in Fig. 15A the angle ε between the tray and the lid is around 190°, however the skilled person understands that angles larger than 180 are also possible, where increasing angle will lead to sharper negative angles at the corresponding outer peripheral rim 419d of the lid 402. Hereby it is possible to use a manufacturing process according to described in WO 2006/057610 while still producing a clamshell product having a lid 402 comprising negative draft angle in one end, preferably at the outer rim end 419d which opposite the hinge portion 403. When having closed a clamshell type container 400 having such negative draft angle at the outer rim portion 419d, the negative draft angle of the rim of the lid 402 will cooperate with the hinge portion 403 creating a strong frictional drag and providing a very efficient locking mechanism with substantially no risk of popping up once closed. Referring to Fig. 16A, in a closed position the male and female members 424, 426 are engaged with one another in a cone clutch like engagement, the pressure of the third segment 419d' " of the lid 402 against the matching third segment 409d" ' of the tray 401 - said second and third bent and/or deflected segments 409d" and 409d" ' acting as a spring - is maintained, which in combination also with the negative draft angle and the friction properties of the material of the packaging container ensures an efficient frictional drag between the lid 402 and the tray 401 and hence a safe closure. It is understood that the alignment of the tray in relating to the lid during production can be applied to any clamshell-type container, giving the same advantageous result.

In all the four embodiments, the locking mechanism includes locking means along a major part of the periphery of the locked packaging container; in the first embodiment in fact around the whole circumference of the container, and in the second, third and fourth embodiments along more than half of the circumference. This of course promotes an efficient locking, and sealing efficiency, but also locking mechanisms of the type described, or other locking mechanisms within the scope of the patent claims, which have a shorter total length of extension along the periphery of the packaging container, e.g. a number of separate locking members distributed around the periphery, can be considered.

In case of a clamshell type container, as the herein described second, third and fourth embodiment, the locking means along the side walls 217, 218 provides a guiding function in addition to the locking function, meaning that the sections of the rim 209 of the tray 201 and of the rim 219 of the lid 202 upon closing of a clamshell container will cooperate for guiding the tray and the lid into a rightful, sealing position as closing operation advances. Hereby a friction locking is achieved very early when initiating closing operation, i.e. a friction locking will arise substantially already when said second and third sections 209b, 209c at the corner of the tray 201 meet the second and third sections 219b, 219c of the lid 202, and will continue to securely lock the tray and the lid together until a point when also the front sections

209d, 219d of the tray and lid respectively also contact each other in a clutch coupling engagement and the container is completely closed, e.g. as shown in Fig. 10. It is understood that the advantage of the guiding function applies also to the other clamshell-type embodiments described herein.

It should be understood that the four described embodiments represent just a few examples which shall not be interpreted as any limitation of the scope of the invention. For example, the packaging container need not have four corners. More as well as fewer corners may very well be conceived.

Claims

PATENT CLAIMS

1. Packaging container (100,200,300, 400) with a locking mechanism, said

container comprising a first part referred to as tray (101,201,301, 401) and a second part, referred to as lid (102,202,302, 402), which are secured to one other as the container is locked, c h a r a c t e r i z e d in

- that the packaging container consists substantially of a cellulose fibre material made from stock,

that in said locking mechanism of the container a portion of one of said tray and lid is a male member (124,224,324,424) and a portion of another one of said tray and lid is a female member (126,226,326,426), that the male member has a first surface (120', 121 '), and the female member has a second surface (104b', 105b'), said first and second surfaces engaging one another in the closed container,

that said first and second surfaces have an extension along at least a section of the circumference of the container, and

that the locking mechanism also satisfies one or both of the following conditions, namely

a) that the intersection between I: the lines of intersection between said first and second fibre material surfaces and a first vertical plane, which is a radial plane and II: a vertical plane which is perpendicular to said first vertical plane, form a wedge angle (β), causing the fibre material surfaces of the male and female members to engage one another in the mode of a clutch coupling when contacted, and

b) that the frictional drag between the surfaces of the male and female members in their closing positions is enhanced by a spring force and a normal force developed between the male and female members during the closing operation.

2. Packaging container according to claim 1, c h a r a c t e r i z e d in that said normal force developed by one of the male and female members upon the other one causes said other member to be at least slightly deflected.

3. Packaging container according to claim 2, c h a r a c t e r i z e d in that said other member is tightened as a spring when it is deflected.

4. Packaging container according to any of claims 1-3, characterized in that the surfaces of the male and female members are caused to contact one another in the mode of a clutch coupling when contacted, and that the frictional drag between the surfaces of the male and female members in their closing positions is enhanced by a spring force and a normal force developed between the male and female members during the closing operation.

5. Packaging container according to any of claims 1-4, characterized in that the female member (126) is a member of the tray (101) and that the male member (124) is a member of the lid (102).

6. Packaging container according to claim 5, characterized in that the female member consists of a space in the tray (101) defined as a region between a shelf (109) at a vertical distance from the bottom (103) of the tray and a female flange (110) at a vertical distance from the shelf, that a wall section (104b,

105b, 106b) between the shelf and the flange is straight in cross section and is inclined outwards, the inner surface (104b', 105b', 106b') of said wall section forming a first surface of a cone clutch, that the male member (124), which forms part of the lid, has an extension in the vertical direction corresponding to the extension in the vertical direction of the female member, that the male member also is inclined outwards at the same angle of inclination as the female member, that the male member has a base (119), which contacts the female shelf, and a male flange (123), which contacts the female flange in the locking position of the male and female members.

7. Packaging container according to claim 6, characterized in that the female flange (110) has a larger extension in the horizontal direction than the male flange (123).

8. Packaging container according to any of claims 5-7, characterized in that the female and male members extend continuously around the circumference of the packaging container.

9. Packaging container according to any of claims 1-4, characterized in that the female member (226,326,426) is a member of the lid and that the male member (224,324,424) is a member of the tray.

10. Packaging container according to claim 9, characterized in that the packaging container is a clamshell packaging container, and that the male and female members form rim sections (209a-d; 219a-d) of the tray and lid, respectively.

11. Packaging container according to claim 9, characterized in that the packaging container is a clamshell packaging container, that the container has a hinge (203,303, 403) extending along a portion of the periphery of the container, and that the locking mechanism extends continuously or discontinuously at least along the periphery of the side opposite the hinge.

12. Packaging container according to claim 10 and 11, characterized in that the male member is formed of a convexly bent rim section including a vertex (209V,409V) pointing upwards and an outer segment (209d"') which in a vertical sectional plane forms a first angle (γ) to a vertical line in said sectional plane prior to engagement with the female member, that the female member also includes an outer segment (219d"') which when contacting the male member, but prior to locking engagement with the male member, forms a second angle (δ) which is smaller than said first angle, and that the outer segment of the female member is provided to deflect the corresponding outer segment of the male member when completing the locking operation, such that a spring force of the outer segment of the male member will be developed, causing the outer segments of the male and female members to be pressed against one another.

13. Packaging container according to claim 12, characterized in that also the female member (326) is convexly bent including inner (319d') and outer (319d' ' ') segments and a vertex on top of the convexly bent female member, that said inner segment (319d') of the female member is straight and is inwardly inclined, that the male member (324) includes an inner, straight segment (309d'), which also is inwardly inclined and is parallel with the inner straight segment of the female member when the container is locked, establishing a cone clutch between the male and female members in combination with the spring force related engagement between the outer segments of the male and female members.

14. Packaging container according to claim 12, characterized in that the outer segment (419d' ' ') of the female member is significantly longer in the vertical direction than the outer segment (409d'") of the male member, that said first angle (γ), which is the inclination angle of the outer segment (409d"') of the male member prior to engagement with the female member, amounts to at least 20°, preferably to at least 25°, and that said second angle (δ), which is the inclination angle of the outer segment of the female member, does not exceed 15°, preferably does not exceed 12°.

15. Packaging container according to claim 14, c h a r a c t e r i z e d in that said outer parts of the male and female members have terminating concave segments (409d^IV , 419d^IV ) with end tips (429,430) pointing outwards, and that the extension of the terminating concave segment (419d^IV) of the female member in the horizontal direction is essentially larger than the extension of the terminating concave segment

(409d^IV) of the male member in the horizontal direction prior to locking

engagement of the male and female members, said larger extension of the terminating concave segment (419d^IV) of the female member in the horizontal direction providing a corresponding larger stiffness and resistance to deflection of the outer part of the female member in the horizontal direction.

16. Packaging container according to any of the preceding claims,

c h a r a c t e r i z e d in that the surfaces of the locking mechanism, including male and female member surfaces of the tray and of the lid in contact with one another in the closed and locked container, are cellulose fibre material surfaces of the container.

17. Packaging container according to claim 16, c h a r a c t e r i z e d in that the packaging container is made from stock.

18. A method for producing a clamshell packaging container (200, 300, 400) comprising a locking mechanism, wherein the method comprises the steps of:

a) providing a first tool that is permeable to air and water, which first tool is arranged to accommodate a fibre product comprising a tray (201, 301, 401) and a lid (202, 302, 402) connected via a hinge portion (203, 303, 403),

b) providing a second tool arranged to essentially match the first tool, and heating the second tool to a temperature of at least 220°C,

c) providing a moulding tank and feeding stock consisting substantially of a cellulose fibre to the moulding tank,

d) immersing the first tool in the stock in the tank,

e) forming an embryonic fibre product on the first tool by applying suction through the first tool, f) removing the first tool from the stock,

g) bringing the first tool against the second tool such that the formed fibre product is sandwiched between the first and the second tool and heated by the second tool such that at least a part of the water in the formed fibre product is vaporized, and

h) dewatering the formed fibre product until it has reached a dry solids content of at least 70% after which the fibre product is subjected to drying,

wherein:

- the first and second tools are designed to create a locking mechanism in the container, where said locking mechanism comprises a portion of one of said tray and lid which is a male member (224,324,424) and a portion of another one of said tray and lid which is a female member (226,326,426),

- the male member has a first surface (209, 309, 409), and the female member has a second surface (219, 319, 419), said first and second surfaces engaging one another in a closed clamshell container,

- said first and second surfaces have an extension along at least a section of the circumference of the container (200, 300, 400), and the first and second tools are arranged so that the intersection between I: the lines of intersection between said first and second fibre material surfaces and a first vertical plane, which is a radial plane and II: a vertical plane which is perpendicular to said first vertical plane, form a wedge angle (β), causing the fibre material surfaces of the male and female members to engage one another in the mode of a clutch coupling when contacted, and

-the first and second tools are arranged so that the clamshell packaging container during production is accommodated with its tray and lid arranged in an angle (ε) in relation to one another, which angle (ε) is larger than 180°.

19. Packaging container produced by means of a method according to claim 18.

20. Packaging container according to claim 19, c h a r a c t e r i z e d in that the container is a clamshell packaging container, that the container has a hinge

(203,303, 403) extending along a portion of the periphery of the container, and that the locking mechanism extends continuously or discontinuously at least along the periphery of the side opposite the hinge.

21. A method for producing a clamshell packaging container (100, 200, 300, 400) comprising a locking mechanism, wherein the method comprises the steps of: a) providing a first tool that is permeable to air and water,

d) immersing the first tool in the stock in the tank,

e) forming an embryonic fibre product on the first tool by applying suction through the first tool,

f) removing the first tool from the stock,

wherein:

- the first and second tools are designed to create a locking mechanism in the container, where said locking mechanism comprises a portion of one of said tray and lid which is a male member (124,224,324,424) and a portion of another one of said tray and lid which is a female member (126,226,326,426),

- the male member has a first surface (120', 121 '), and the female member has a second surface (104b', 105b'), said first and second surfaces engaging one another in a closed clamshell container,

- said first and second surfaces have an extension along at least a section of the circumference of the container, and the first and second tools are arranged so that the intersection between I: the lines of intersection between said first and second fibre material surfaces and a first vertical plane, which is a radial plane and II: a vertical plane which is perpendicular to said first vertical plane, form wedge angle (β), causing the fibre material surfaces of the male and female members to engage one another in the mode of a clutch coupling when contacted.