Containers

Abstract

The invention provides, in one aspect, a method of making a container having a body and a rim defining an opening for the container, the opening being capable of being closed by a push-on lid, the container being made of a material which is susceptible to deformation when heated. In other aspects, the invention also provides a container and an apparatus for making a container.

1 . A method of making a container having a body and a rim defining an opening for the container, the opening being capable of being closed by a push-on lid, the container being made of a material which is susceptible to deformation when heated, the method comprising the steps of:
 a) providing a preform made of a material which is susceptible to deformation when heated, the preform being in the shape of a closed-end tube with a rim at its mouth, the rim comprising: an outward generally-radial flange having an upper surface and a lower surface, the flange extending from a radially inner end to a radially outer end, the tube depending from the radially inner end of the flange; a first detent simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange, the first detent located at or near the radially inner end of the flange; and a second detent simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange, the second detent located at or near the radially outer end of the flange;   b) placing the preform in a pressure moulding apparatus at an elevated temperature with the preform being located in the apparatus at least in part by the second detent;   c) expanding the tube under pressure to form the body of the container; and then   d) moving the first detent downwardly and outwardly relative to the second detent so that the first detent projects inwardly into the opening for the container;   wherein the movement of the first detent downwardly and outwardly relative to the second detent is controlled to only occur after step c), and such that after step d) the first detent projects inwardly into the container, with its elongate axis at an angle of from 60° to 120° to the elongate axis of the second detent, such that the first detent forms an internal rim.   
     
     
         2 . The method of  claim 1 , wherein the first detent is shielded from the pressure applied in step c) due to it being located in the pressure moulding apparatus in a location that is not exposed to the pressure applied in step c). 
     
     
         3 . The method of  claim 2 , wherein the first detent is located in a section within the pressure moulding apparatus, wherein this section is separated from the inside of the tube which is to be exposed to pressure, to cause expansion of the tube, by a shielding wall. 
     
     
         4 . The method of  claim 1 , wherein the inward projection of the detent after step d) is such that its elongate axis is at an angle of from 75° to 105° to the elongate axis of the second detent. 
     
     
         5 . The method of  claim 1 , wherein the inward projection of the detent after step d) is such that it does not extend beyond 95° to the elongate axis of the second detent. 
     
     
         6 . The method of  claim 1 , wherein in step d) the movement of the first detent is achieved by applying downward pressure of 600 kPa or higher to the first detent, whilst supporting the second detent in a fixed position, so as to cause the first detent to move downwardly and outwardly with respect to the second detent. 
     
     
         7 . The method of  claim 6 , wherein the pressure used is from 1000 to 2000 kPa. 
     
     
         8 . The method of  claim 1 , wherein in step d) the pressure is applied for from 0.05 to 1 second. 
     
     
         9 . The method of  claim 1 , wherein in step d) the pressure is applied hydraulically, pneumatically or elastically. 
     
     
         10 . The method of  claim 1 , wherein step d) uses a mechanical device or a source of pressurised gas to place controlled downward pressure on the first detent. 
     
     
         11 . The method of  claim 1 , wherein the preform provided in step a) has been injection moulded. 
     
     
         12 . The method of  claim 11 , wherein step a) comprises the step of injection moulding the preform in an injection moulding apparatus in order to provide the preform. 
     
     
         13 . The method of  claim 1 , wherein the preform has three or more detents simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange. 
     
     
         14 . The method of  claim 13 , wherein the preform has a third detent located between the first detent and the second detent, wherein the third detent and second detent between them define a trough, suitable for receipt of a correspondingly shaped sealing projection on the container lid, there being a sealing portion in the trough for sealing engagement with the sealing projection of the lid. 
     
     
         15 . The method of  claim 1 , wherein the first detent extends continuously around the mouth of the preform provided in step a). 
     
     
         16 . The method of  claim 1 , wherein the first detent extends discontinuously around the mouth of the preform provided in step a), being made up of two or more sections. 
     
     
         17 . The method of  claim 1 , wherein the preform is made from a thermoplastic material. 
     
     
         18 . The method of  claim 17 , wherein the material is selected from polyethylene terephthalate, polyethylene naphathalate, and co-polymers and blends of these two materials. 
     
     
         19 . The method of  claim 1 , wherein step b) is carried out using pressure moulding apparatus having mould parts defining a mould cavity and comprising: (i) a securing component that permits the location of the preform in the mould cavity with the second detent in a fixed location therein, (ii) a generator of a pressure differential between the interior of the tube and the exterior to expand the tube into contact with the mould parts defining the mould cavity; (iii) a shield for shielding the first detent from the pressure that is applied to expand the tube; and (iv) a source of controlled downward pressure that can act to move the flange and the first detent downwardly and outwardly relative to the second detent such that the upper surface of the flange faces inwardly and the first detent projects inwardly into the opening for the container, with its elongate axis at an angle of from 60° to 120° to the elongate axis of the second detent, such that the first detent forms an internal rim. 
     
     
         20 . The method of  claim 1 , wherein step c) comprises applying differential pressure between the interior of the preform and the exterior of the preform, to expand the tube portion to form the body of the container. 
     
     
         21 . The method of  claim 1  wherein the method further comprises the step of:
 e) filling the container with a product. 
 
     
     
         22 . The method of  claim 1  wherein after step d) or optional step e), the method further comprises the step of:
 f) fitting a lid to the container, in which the lid includes (i) a trough, suitable for receipt of and engagement with the second detent, and (ii) an engaging portion for receipt under and engagement with the inner rim formed by the first detent, to secure the lid on the container. 
 
     
     
         23 . An apparatus for making a container having a body and a rim portion defining an opening for the container, the opening being capable of being closed by a push-on lid, the apparatus comprising:
 pressure moulding apparatus having mould parts defining a mould cavity and comprising: (i) a securing component that permits the location of the preform in the mould cavity with the second detent in a fixed location therein, (ii) a generator of a pressure differential between the interior of the tube and the exterior to expand the tube into contact with the mould parts defining the mould cavity; (iii) a shield for shielding the first detent from the pressure that is applied to expand the tube; and (iv) a source of controlled downward pressure that can act to move the flange and the first detent downwardly and outwardly relative to the second detent such that the upper surface of the flange faces inwardly and the first detent projects inwardly into the opening for the container, with its elongate axis at an angle of from 60° to 120° to the elongate axis of the second detent, such that the first detent forms an internal rim.   
     
     
         24 . The apparatus of  claim 23 , wherein the shield is provided by the pressure moulding apparatus including a section within which the first detent can be located, which section can act to shield the first detent from the pressure that is applied to expand the tube. 
     
     
         25 . The apparatus of  claim 24 , wherein the pressure moulding apparatus includes a corridor, within which the first detent can be located, whereby when the preform is in the apparatus a wall of the corridor contacts the preform at a point between where the tube extends from the radially inner end of the flange and the first detent, such that the wall forms a barrier between the first detent and the parts of the preform that are exposed to the pressure that is applied to expand the tube. 
     
     
         26 . The apparatus of  claim 23  wherein the source of controlled downward pressure can apply a pressure of 1000 kPa or higher. 
     
     
         27 . The apparatus of  claim 23  wherein the source of controlled downward pressure can apply a pressure for from 0.1 to 1 second. 
     
     
         28 . The apparatus of  claim 23  wherein the source of controlled downward pressure comprises a mechanical device or a source of pressurised gas to place controlled downward pressure on the first detent. 
     
     
         29 . The apparatus of  claim 23  wherein the apparatus further comprises:
 injection moulding apparatus shaped and arranged to produce a preform in the shape of a closed-end tube with a rim at its mouth, the rim comprising: (a) an outward generally-radial flange having an upper surface and a lower surface, the flange extending from a radially inner end to a radially outer end, the tube depending from the radially inner end of the flange; (b) a first detent simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange, the first detent located at or near the radially inner end of the flange; and (c) a second detent simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange, the second detent located at or near the radially outer end of the flange. 
 
     
     
         30 . A container having a body and a rim defining an opening for the container, the opening being capable of being closed by a push-on lid, the container being made of a material which is susceptible to deformation when heated, and the container having a first detent projecting inwardly into the container to form an internal rim, the container being obtainable by a method comprising the steps of:
 a) providing a preform made of a material which is susceptible to deformation when heated, the preform being in the shape of a closed-end tube with a rim at its mouth, the rim comprising: an outward generally-radial flange having an upper surface and a lower surface, the flange extending from a radially inner end to a radially outer end, the tube depending from the radially inner end of the flange; a first detent simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange, the first detent located at or near the radially inner end of the flange; and a second detent simultaneously formed with the flange as an upstanding elongate projection from the upper surface of the flange, the second detent located at or near the radially outer end of the flange;   b) placing the preform in a pressure moulding apparatus at an elevated temperature with the preform being located in the apparatus at least in part by the second detent;   c) expanding the tube under pressure to form the body of the container; and then   d) moving the first detent downwardly and outwardly relative to the second detent so that the first detent projects inwardly into the opening for the container;   wherein the movement of the first detent downwardly and outwardly relative to the second detent is controlled to only occur after step c), and such that after step d) the first detent projects inwardly into the container, with its elongate axis at an angle of from 60° to 120° to the elongate axis of the second detent, such that the first detent forms an internal rim.