CA1207681A - Injection molded plastic container - Google Patents
Injection molded plastic containerInfo
- Publication number
- CA1207681A CA1207681A CA000414238A CA414238A CA1207681A CA 1207681 A CA1207681 A CA 1207681A CA 000414238 A CA000414238 A CA 000414238A CA 414238 A CA414238 A CA 414238A CA 1207681 A CA1207681 A CA 1207681A
- Authority
- CA
- Canada
- Prior art keywords
- ribs
- axis
- rim
- container
- rib
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
INJECTION MOLDED PLASTIC CONTAINER
An injection molded plastic container having a longitudinal axis comprising a bottom, a rim defining an opening, a continuous side wall joining the bottom and the rim and disposed symmetrically about said axis, a point of injection centrally located in the bottom, a molding terminus defined by said rim and a plurality of pairs of ribs integral with and superimposed on the exterior surface of said side wall, said ribs being solid in transverse cross-section and forming a symmetrical pattern on said surface wherein each rib is curved and forms an acute angle throughout its length to the shortest surface distance between the point of injection and the rim, half of the ribs are curved as a mirror image of the other half of the ribs, each pair of ribs is a mirror image pair which join at said rim and are disposed in spaced relationship at said bottom, said pairs being spaced about said axis with each rib of each pair crossing once only the next adjacent rib of the next adjacent pair and no other rib.
INJECTION MOLDED PLASTIC CONTAINER
An injection molded plastic container having a longitudinal axis comprising a bottom, a rim defining an opening, a continuous side wall joining the bottom and the rim and disposed symmetrically about said axis, a point of injection centrally located in the bottom, a molding terminus defined by said rim and a plurality of pairs of ribs integral with and superimposed on the exterior surface of said side wall, said ribs being solid in transverse cross-section and forming a symmetrical pattern on said surface wherein each rib is curved and forms an acute angle throughout its length to the shortest surface distance between the point of injection and the rim, half of the ribs are curved as a mirror image of the other half of the ribs, each pair of ribs is a mirror image pair which join at said rim and are disposed in spaced relationship at said bottom, said pairs being spaced about said axis with each rib of each pair crossing once only the next adjacent rib of the next adjacent pair and no other rib.
Description
3~6f~
INJ~CTION MOLDED PLASTIC CONTAINER
This invention relates to an injection molded plastic container and particularly, though no~
exclusively, to a propropylene cup or tumblerO
In the field of injection molding of plastic containers, such as cups and tumblers, for holding bevera~es, the produc~ion volume o such articles of 10 manuf~cture demands minimum cost, coupled wi~h an appearance and structure which is perfectly acceptable to the public. Accordingly, the utilization o~ a minimum volume of injection moldable thermoplastic material is of primary importance9 provided the 15 required structural strength and aesthetic qualities can be achieved. There have been developments over a number of years which have provided the injection molding of cups or tumblers having apparently a minimum oE material volume coupled with suffiçien~ strength in 20 the end pro~uct. This has entailed the u~e of reinforcing beads, channels or ribs aligned in the direction of the mold filling or molding and relatively closely spaced together to permit a minimum of wall material extending between the ribs. The materials 25 which have been found to provide a satisfactory producl ~or example, polystyrene ~which is relatively : ~ brittle) impose significant limitation on the ~inimum wall thickness that can be achieved consistent with adequate strength. Traditionally, the beads or ribs 30 which reinforce the wall have extended by the shortçst distance from the mold filling poi~t to the urthest point at which the mold is to be illed. This proble~
of mold filling has restric~:ed the arrangement of beads and ribs which might be.utili~ed to maximi2e wall strength with minimum wall thickness.
U.S. Patent 3679119 sought to overcome previous limitations in the molding oÇ polystyrene containers -to achieve minimum wall thickness consistent with strength and adequate mold filling by providing a structural 5 plastic wall for a container having ribs or feeding ducts extended at an angle to the shortest distance between the feed point of the mold and the end of the mold, including superimposed ribs of corresponding complimentary angle defining with the irst ribs a 10 lattice network which embodies a leakage path by virt~e of which a webbed structure is formed and fed from said ribs or feeding channels in a manner segmen~ing the to~al area of the article into small web areas bourlded entirely by the rib feeding channels so tha~ the total 15 volume of the webs is minimized and comprises a major portion of ~he material oE the articleO The disclosure o~ this prior art patent teaches the use o~ a substantially frusto-conical wall and poses substantial problems in mold stripping when thermoplastie ma~erials 20 which are transparent or aesthetically more pleasing than polystyrene are used.
`` Attempts have been made to produce injection molded ; tumblers from polypropylene -to take advantage of ~he pntentially ~hin wall, low material usage and : ~ 25 relatively resilient characteristics of this material.
~lowever, attempts to use -this material to produce an aesthetically satisfactory container have proved economically unsuccessful in view of problems including, for example, ~he difficulty of stripping a polypropylene container from a mold due to its relatively high shrinkage during the cooling process while in the mold due to the excessive surface contact pressure resulting from the shrinkage. This may be overcome, at least partially, by using a vapor-honed surface which results in a matt surface on the container produced, so that, upon shrinkage of the material, the surface of the mold and the container drag over one anoth~r and release ~or~ easily. The product produced wi~h such a vapor-honed sur~ace is not S aes~hetically satisfacto~y and attempts to produce an optically transparent or transluc~n~ con~ainer with a smooth surface which is aesthetically pleasing and which can be stripped readily from a production ~old in an econo~ical manner have, until the present invention, 10 failed.
It is an object of the present invention to provide a shape and structu~e of a container, or example~ a cup or tumbler, which may be made with a smooth (polished), non-matt surface so as to be transparent or~
15 translucen~ with improved material economy coupled with an aesthetically pleasing shape and construction having adequate strength asld which, due to its design9 can be molded from polypropylene~
The invention provides an injection mold0d plas~ic container having a longitudinal axis comprising a bottom, a rim defining an opening, a contimlous side wall joinin~ the bottom and the rim and disposed symmetrically about said axis, a point of injection centrally located in the bottom, a molding terminus deined by said rim and a plurali~y of pairs of ribs integral with and superimposed on a surface o said side wall, said ribs being solid in transverse cross-section and forming a symmetrical pattern on s:aid ~:; surface wherein each rib is curved and forms an acute : 30 an~le throughout its length ~o the shortest sur~ace dis~ance between the point o injection and th~ rinl, half of the ribs are curved as a mirror image o~ th~
:~ other half o~ the ribs, each pair o ribs is a mirror ~ ima~e pair which join at said ri~ and are dispo~ed i~
: ~ 35 spaced relationship at said bottom, said pairs bein~
Jt~
spaced abou-t said axis with each rib of each pair crossing once only the next adjacent rib of the next adjacent pair and no other rib, the side wall is divided longitudinally of the axis into an upper frusto-conical portion adjacent the rim and a lower curved wall portion adjacent the bottom wall~ the frusto-conical portion tapering inwardly and downwardly to join the lower curved wall portion which is curved in a plane containing said axis.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Fig. 1 is a perspective view of a beverage container according to the present invention;
Fig. 2 is an elevation of the container of Fig. l;
Fig. 3 is a development of the surface pattern of a portion of the side wall of the container oE Fig. l;
Fig. 4 is an underview of the container oE Fig. l;
Fig. 5 is a plan view of the container of Fig. l;
Fig. 6 is a sectional elevation showing the side wall cross section of the container of Fig. l;
Fig. 7 is a Eragmentary cross section oE a portion of the side wall of the ~ontainer of Fig. 1 showing the cross sectional shape o-f a rein-forcing rib; and Fig. 8 is a fragmentary view of an alternative arrangement of cross ribs defining a pattern on a container otherwise similar to that shown in Fig. 1.
'~3 ~o~
-4a-Referring to the drawings, a polypropylene container 1 in the form of a cup or tumbler comprises a lip or rim 2 defining an upwardly facing circular opening 3, a continuous side wall 4 having a plurality of reinforcing and feed channel ribs 5 defined on the outer surface thereof~ and a bottom which includes a stacking base 6 defining a support base for the container and a bottom panel 7 of generally convex Eorm with the convex surface thereof facing the interior of the container.
The lip 2 is in the form of an outwardly extending annular flange of generally semi-circular cross section (Fig. 6) with the inner extent of the flange communicating smoothly with an upper portion 8 of the ~20~76~
sidewall 4, which upper portion is of frusto-conical form tapering inwardly from the opening 3 with an includ~d angle of 10 . The upper portion 8 of the sidewall 4 extends for approximately forty percent of the overall hei~ht of the container. The lowPr extremity of the upper portion ~ merges smoothly with the lower portion 9 of the side wall 4, which lower portion is an circular ~urved wall having a substantially constant radius R in a plane containin~
10 the longitudinal axis 10 of the container. T~e lower end of ~he lower portion 9 t~rminates in the stacking base 6 which is in ~he form of a substantially cylindrical wall which interconnects the lower portio~
9 with the bottom panel 7 to provide an upwardly ~acing annular stacking surface 11 capable of being engaged by an annular lower surface 12, defined by the low~r termination of the stacking base 6, o another ~imilar container when these containers are nes~ed one within the oth~r. The lower annuIar surface 12 interconnects with the convex bottom panel 7. The annular sur~ace 12 provides a stable surface for standing the container in an upright position on, ~lat horizontal su~ace~ h : .point o in jection is disposed oentrally on the bo~tom panel 7.
`~ ~ 25 The rein~orcing ribs and feed channels 5 are curved and each extend from the rim 2 to the stacking base 6 on the exterior of ~he side wall 4 with which they are integrally formed. Each rib is disposed at an acute angle throughout its length to a line defining she shortest path from the rim to the stacking base 6. The ribs 5 arc formed in mirror image pairs 13 ~o f.orm an overlapping pattern of the pairs in which each rib of a pair of ribs 13 crosses over the next adjac~n~ rib of ~he next adjacent pair of ribs 13 once only to form a : ~ 35 lattice pattern of ribs each of which crosses once only with another such rib with the upper ends of each pair of ribs coming together at the rim 2 and with ends of the ribs 5 at the lower end of the side wall 5 being disposed in equi-angular spacing about the axis 10 5 around the lower end of the side wall. The cross over poin~s of the ribs and the points at which the pairs of ri~s come together at the rim 2 are each equi angularly disposed around the wall about the axis 10 ~o define a pattern of ribs of symmetrical form with the c~oss over points disposed on the frusto-conical upper wall portion B.
The ribs are of subs~antially constant part circular cross section as shown in Fig. 7.
In this specific example of the container there are lS 30 ribs forming 15 pairs equi-angularly spaced apar~
around the container about the axis 10 with each rib 5, as seen in the development (Fig. 3) being deine~ by a curva~ure of constan~ radius R. In this specific example the container has a wall thickness of 0.010 20 inches with the ribs projecting 0.007 inches radially outwardly from the wall to define a reinforcing - latticework for the wall areas defined between the ribs. The stacking base has a radial thickness o~
0.016 inches and ~he bo~tom panel has a thickness of ~ 25 0.018 inches. The c-ontainer has an overall container : : ~ height of 3.3 inches with a diameter at its upp~r extreml~y of 3.135 inches and a diameter at its lower : ~extremity of 1~8 inches. The radius of the lower portion of the side wall is 5 inches and the raclius~of ~: 30 curvatu~e of each rib 5 is 8 inches.
will bè appreciated that the specific d~ign ~: features and climensions herebefore given with reerence .
:to the drawings, are by way of example only ancl that a : variety of:diferent dimensional int:errelationships and : 35 plu~alities of pairs of ribs may be utilized without ,, ;
INJ~CTION MOLDED PLASTIC CONTAINER
This invention relates to an injection molded plastic container and particularly, though no~
exclusively, to a propropylene cup or tumblerO
In the field of injection molding of plastic containers, such as cups and tumblers, for holding bevera~es, the produc~ion volume o such articles of 10 manuf~cture demands minimum cost, coupled wi~h an appearance and structure which is perfectly acceptable to the public. Accordingly, the utilization o~ a minimum volume of injection moldable thermoplastic material is of primary importance9 provided the 15 required structural strength and aesthetic qualities can be achieved. There have been developments over a number of years which have provided the injection molding of cups or tumblers having apparently a minimum oE material volume coupled with suffiçien~ strength in 20 the end pro~uct. This has entailed the u~e of reinforcing beads, channels or ribs aligned in the direction of the mold filling or molding and relatively closely spaced together to permit a minimum of wall material extending between the ribs. The materials 25 which have been found to provide a satisfactory producl ~or example, polystyrene ~which is relatively : ~ brittle) impose significant limitation on the ~inimum wall thickness that can be achieved consistent with adequate strength. Traditionally, the beads or ribs 30 which reinforce the wall have extended by the shortçst distance from the mold filling poi~t to the urthest point at which the mold is to be illed. This proble~
of mold filling has restric~:ed the arrangement of beads and ribs which might be.utili~ed to maximi2e wall strength with minimum wall thickness.
U.S. Patent 3679119 sought to overcome previous limitations in the molding oÇ polystyrene containers -to achieve minimum wall thickness consistent with strength and adequate mold filling by providing a structural 5 plastic wall for a container having ribs or feeding ducts extended at an angle to the shortest distance between the feed point of the mold and the end of the mold, including superimposed ribs of corresponding complimentary angle defining with the irst ribs a 10 lattice network which embodies a leakage path by virt~e of which a webbed structure is formed and fed from said ribs or feeding channels in a manner segmen~ing the to~al area of the article into small web areas bourlded entirely by the rib feeding channels so tha~ the total 15 volume of the webs is minimized and comprises a major portion of ~he material oE the articleO The disclosure o~ this prior art patent teaches the use o~ a substantially frusto-conical wall and poses substantial problems in mold stripping when thermoplastie ma~erials 20 which are transparent or aesthetically more pleasing than polystyrene are used.
`` Attempts have been made to produce injection molded ; tumblers from polypropylene -to take advantage of ~he pntentially ~hin wall, low material usage and : ~ 25 relatively resilient characteristics of this material.
~lowever, attempts to use -this material to produce an aesthetically satisfactory container have proved economically unsuccessful in view of problems including, for example, ~he difficulty of stripping a polypropylene container from a mold due to its relatively high shrinkage during the cooling process while in the mold due to the excessive surface contact pressure resulting from the shrinkage. This may be overcome, at least partially, by using a vapor-honed surface which results in a matt surface on the container produced, so that, upon shrinkage of the material, the surface of the mold and the container drag over one anoth~r and release ~or~ easily. The product produced wi~h such a vapor-honed sur~ace is not S aes~hetically satisfacto~y and attempts to produce an optically transparent or transluc~n~ con~ainer with a smooth surface which is aesthetically pleasing and which can be stripped readily from a production ~old in an econo~ical manner have, until the present invention, 10 failed.
It is an object of the present invention to provide a shape and structu~e of a container, or example~ a cup or tumbler, which may be made with a smooth (polished), non-matt surface so as to be transparent or~
15 translucen~ with improved material economy coupled with an aesthetically pleasing shape and construction having adequate strength asld which, due to its design9 can be molded from polypropylene~
The invention provides an injection mold0d plas~ic container having a longitudinal axis comprising a bottom, a rim defining an opening, a contimlous side wall joinin~ the bottom and the rim and disposed symmetrically about said axis, a point of injection centrally located in the bottom, a molding terminus deined by said rim and a plurali~y of pairs of ribs integral with and superimposed on a surface o said side wall, said ribs being solid in transverse cross-section and forming a symmetrical pattern on s:aid ~:; surface wherein each rib is curved and forms an acute : 30 an~le throughout its length ~o the shortest sur~ace dis~ance between the point o injection and th~ rinl, half of the ribs are curved as a mirror image o~ th~
:~ other half o~ the ribs, each pair o ribs is a mirror ~ ima~e pair which join at said ri~ and are dispo~ed i~
: ~ 35 spaced relationship at said bottom, said pairs bein~
Jt~
spaced abou-t said axis with each rib of each pair crossing once only the next adjacent rib of the next adjacent pair and no other rib, the side wall is divided longitudinally of the axis into an upper frusto-conical portion adjacent the rim and a lower curved wall portion adjacent the bottom wall~ the frusto-conical portion tapering inwardly and downwardly to join the lower curved wall portion which is curved in a plane containing said axis.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Fig. 1 is a perspective view of a beverage container according to the present invention;
Fig. 2 is an elevation of the container of Fig. l;
Fig. 3 is a development of the surface pattern of a portion of the side wall of the container oE Fig. l;
Fig. 4 is an underview of the container oE Fig. l;
Fig. 5 is a plan view of the container of Fig. l;
Fig. 6 is a sectional elevation showing the side wall cross section of the container of Fig. l;
Fig. 7 is a Eragmentary cross section oE a portion of the side wall of the ~ontainer of Fig. 1 showing the cross sectional shape o-f a rein-forcing rib; and Fig. 8 is a fragmentary view of an alternative arrangement of cross ribs defining a pattern on a container otherwise similar to that shown in Fig. 1.
'~3 ~o~
-4a-Referring to the drawings, a polypropylene container 1 in the form of a cup or tumbler comprises a lip or rim 2 defining an upwardly facing circular opening 3, a continuous side wall 4 having a plurality of reinforcing and feed channel ribs 5 defined on the outer surface thereof~ and a bottom which includes a stacking base 6 defining a support base for the container and a bottom panel 7 of generally convex Eorm with the convex surface thereof facing the interior of the container.
The lip 2 is in the form of an outwardly extending annular flange of generally semi-circular cross section (Fig. 6) with the inner extent of the flange communicating smoothly with an upper portion 8 of the ~20~76~
sidewall 4, which upper portion is of frusto-conical form tapering inwardly from the opening 3 with an includ~d angle of 10 . The upper portion 8 of the sidewall 4 extends for approximately forty percent of the overall hei~ht of the container. The lowPr extremity of the upper portion ~ merges smoothly with the lower portion 9 of the side wall 4, which lower portion is an circular ~urved wall having a substantially constant radius R in a plane containin~
10 the longitudinal axis 10 of the container. T~e lower end of ~he lower portion 9 t~rminates in the stacking base 6 which is in ~he form of a substantially cylindrical wall which interconnects the lower portio~
9 with the bottom panel 7 to provide an upwardly ~acing annular stacking surface 11 capable of being engaged by an annular lower surface 12, defined by the low~r termination of the stacking base 6, o another ~imilar container when these containers are nes~ed one within the oth~r. The lower annuIar surface 12 interconnects with the convex bottom panel 7. The annular sur~ace 12 provides a stable surface for standing the container in an upright position on, ~lat horizontal su~ace~ h : .point o in jection is disposed oentrally on the bo~tom panel 7.
`~ ~ 25 The rein~orcing ribs and feed channels 5 are curved and each extend from the rim 2 to the stacking base 6 on the exterior of ~he side wall 4 with which they are integrally formed. Each rib is disposed at an acute angle throughout its length to a line defining she shortest path from the rim to the stacking base 6. The ribs 5 arc formed in mirror image pairs 13 ~o f.orm an overlapping pattern of the pairs in which each rib of a pair of ribs 13 crosses over the next adjac~n~ rib of ~he next adjacent pair of ribs 13 once only to form a : ~ 35 lattice pattern of ribs each of which crosses once only with another such rib with the upper ends of each pair of ribs coming together at the rim 2 and with ends of the ribs 5 at the lower end of the side wall 5 being disposed in equi-angular spacing about the axis 10 5 around the lower end of the side wall. The cross over poin~s of the ribs and the points at which the pairs of ri~s come together at the rim 2 are each equi angularly disposed around the wall about the axis 10 ~o define a pattern of ribs of symmetrical form with the c~oss over points disposed on the frusto-conical upper wall portion B.
The ribs are of subs~antially constant part circular cross section as shown in Fig. 7.
In this specific example of the container there are lS 30 ribs forming 15 pairs equi-angularly spaced apar~
around the container about the axis 10 with each rib 5, as seen in the development (Fig. 3) being deine~ by a curva~ure of constan~ radius R. In this specific example the container has a wall thickness of 0.010 20 inches with the ribs projecting 0.007 inches radially outwardly from the wall to define a reinforcing - latticework for the wall areas defined between the ribs. The stacking base has a radial thickness o~
0.016 inches and ~he bo~tom panel has a thickness of ~ 25 0.018 inches. The c-ontainer has an overall container : : ~ height of 3.3 inches with a diameter at its upp~r extreml~y of 3.135 inches and a diameter at its lower : ~extremity of 1~8 inches. The radius of the lower portion of the side wall is 5 inches and the raclius~of ~: 30 curvatu~e of each rib 5 is 8 inches.
will bè appreciated that the specific d~ign ~: features and climensions herebefore given with reerence .
:to the drawings, are by way of example only ancl that a : variety of:diferent dimensional int:errelationships and : 35 plu~alities of pairs of ribs may be utilized without ,, ;
2~t~
departing from the concepts oE the invention. In this connection, although the coming together of the ribs at the rim provides additional rim and adjacent wall strength, the ribs may be arranged with ends terminating at the rim in spaced apar~ relationship.
The example given is cons~ruc~ed of polypropylene and is transparent with a smooth (polished) surfaçe to provide optical clarity. However, the inven~ion is equally applicable to a polished translucent construction. Addi~ionally, other thermoplastics might be used, for example polyethylene. The construction of the present invention permits the economical production o~ transparent smoothly surfaced containers made of polypropyl~ne with a thin wall construction utilizing a minimum of material and providing an aesthetically pleasing product o~ adequate strength and stability for ~use to dispense liquids. The shape of the container with its curved lower wall portion and relatively short frusto-conical upper wall portion provides adequat~
wall strength and facilitates the easy stripping o the container from an injection mcld when using ~polypropylene with its relatively high shrinka~e rate of 0.20 inches per inch over temperature change ~f 28Q F, without necessitating the use of a vapor-honed surface on the mold with the consequent aesthetically unsatisfactory matt inish on the surface of the container.
It will be appreciated that a solid annular rib could be utilized, instead of the curved cross-section flange, to define the opening at the upper end of the container and that the cross over points of the ribs could be defined by overlapping or contacting portions of adjacent ribs ~as shown in Fig. 8~ wherein ~he ribs do nol completely cross over. Herein such an 3s overlapping or contacting arrangement adjacent ribs;
shall for the purposes of this invention be re~arded as crossing or crossed ribs.
It will be appreciated that the ribs need no~ be equi-an~ularly spaced about the axis provided adequate symmetry is maintained, that the cross p~ints of the ribs need not be all in the same plane and that ~he curvature of the ribs need not be of a cons~ant radius.
The use of polypropylsne permi~s the cons~ruction of a thinner and lighter construction, while achieving a satisf~ctory optical clarity,than is possibl.e with polystyrene containers such as that disclosed in the aforementioned U.S. Patent 3,679,119 and the present inventioh permits the economical reliable production of such polypropylene containers without problems of stripping these from the injection mold, and further, permits the production of high quality containers ~ith greater economy than is possible on the substantially more expensive equipment used in thermoforming containers made oE, for example, styrene/bu~adlene, the cost of which~ without the excessive production costs is greater than the material cost of polypropylene.
i
departing from the concepts oE the invention. In this connection, although the coming together of the ribs at the rim provides additional rim and adjacent wall strength, the ribs may be arranged with ends terminating at the rim in spaced apar~ relationship.
The example given is cons~ruc~ed of polypropylene and is transparent with a smooth (polished) surfaçe to provide optical clarity. However, the inven~ion is equally applicable to a polished translucent construction. Addi~ionally, other thermoplastics might be used, for example polyethylene. The construction of the present invention permits the economical production o~ transparent smoothly surfaced containers made of polypropyl~ne with a thin wall construction utilizing a minimum of material and providing an aesthetically pleasing product o~ adequate strength and stability for ~use to dispense liquids. The shape of the container with its curved lower wall portion and relatively short frusto-conical upper wall portion provides adequat~
wall strength and facilitates the easy stripping o the container from an injection mcld when using ~polypropylene with its relatively high shrinka~e rate of 0.20 inches per inch over temperature change ~f 28Q F, without necessitating the use of a vapor-honed surface on the mold with the consequent aesthetically unsatisfactory matt inish on the surface of the container.
It will be appreciated that a solid annular rib could be utilized, instead of the curved cross-section flange, to define the opening at the upper end of the container and that the cross over points of the ribs could be defined by overlapping or contacting portions of adjacent ribs ~as shown in Fig. 8~ wherein ~he ribs do nol completely cross over. Herein such an 3s overlapping or contacting arrangement adjacent ribs;
shall for the purposes of this invention be re~arded as crossing or crossed ribs.
It will be appreciated that the ribs need no~ be equi-an~ularly spaced about the axis provided adequate symmetry is maintained, that the cross p~ints of the ribs need not be all in the same plane and that ~he curvature of the ribs need not be of a cons~ant radius.
The use of polypropylsne permi~s the cons~ruction of a thinner and lighter construction, while achieving a satisf~ctory optical clarity,than is possibl.e with polystyrene containers such as that disclosed in the aforementioned U.S. Patent 3,679,119 and the present inventioh permits the economical reliable production of such polypropylene containers without problems of stripping these from the injection mold, and further, permits the production of high quality containers ~ith greater economy than is possible on the substantially more expensive equipment used in thermoforming containers made oE, for example, styrene/bu~adlene, the cost of which~ without the excessive production costs is greater than the material cost of polypropylene.
i
Claims (9)
1. An injection molded plastic container having a longitudinal axis comprising a bottom, a rim defining an opening, a continuous side wall joining the bottom and the rim and disposed symmetrically about said axis, a point of injection centrally located in the bottom, a molding terminus defined by said rim and a plurality of pairs of ribs extending from the bottom to the rim integral with and superimposed on a surface of said side wall, said ribs being solid in transverse cross-section and forming a symmetrical pattern on said surface wherein each rib is curved and forms an acute angle throughout its length to the shortest surface distance between the point of injection and the rim, half of the ribs are curved as a mirror image of the other half of the ribs, each pair of ribs is a mirror image pair, said pairs being spaced about said axis with each rib of each pair crossing once only the next adjacent rib of the next adjacent pair and no other rib, the side wall is divided longitudinally of the axis into an upper frusto-conical portion adjacent the rim and a lower curved wall portion adjacent the bottom wall, the frusto-conical portion tapering inwardly and downwardly to join the lower curved wall portion which is curved in a plane containing said axis.
2. A container according to claim 1 wherein the ribs are superimposed on the exterior surface of said side wall.
3. A container according to claim 2 wherein the ribs of each mirror image pair of ribs join together at said rim and are disposed in spaced relationship at said bottom.
4. A container according to claim 3 wherein the pairs of ribs are equi-angularly spaced about said axis and the ends of the ribs at the bottom wall are equi-angularly spaced about said axis.
5. A container according to claim 1 wherein said lower wall portion curvature is of a constant radius.
6. A container according to claim 5 wherein said bottom comprises a stacking base of generally cylindrical form symmetrically disposed about said axis, joined to said lower wall portion to form an annular stacking surface inside said container to receive and support another similar container when nested therein and an annular support surface for supporting said container, with said axis vertical on a horizontal surface, and a bottom panel having a convex surface facing into said container.
7. A container according to claim 3 wherein there are fifteen pairs of ribs evenly disposed about said axis.
8. A container according to claim 1 wherein the crossing points of the ribs are disposed in a plane normal to said axis on the upper frusto-conical portion of the side wall.
9. A container according to claim 1 wherein the plastic is polypropylene.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US31880681A | 1981-11-06 | 1981-11-06 | |
| US318,806 | 1981-11-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207681A true CA1207681A (en) | 1986-07-15 |
Family
ID=23239641
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000414238A Expired CA1207681A (en) | 1981-11-06 | 1982-10-27 | Injection molded plastic container |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1207681A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USD412441S (en) | 1997-11-12 | 1999-08-03 | Crown Cork & Seal Technologies Corporation | Plastic container |
| US5988417A (en) * | 1997-11-12 | 1999-11-23 | Crown Cork & Seal Technologies Corporation | Plastic container having improved rigidity |
| USD425424S (en) | 1997-11-12 | 2000-05-23 | Crown Cork & Seal Technologies Corporation | Plastic container |
| USD429151S (en) | 1997-11-12 | 2000-08-08 | Crown Cork & Seal Technologies Corporation | Plastic container |
-
1982
- 1982-10-27 CA CA000414238A patent/CA1207681A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USD412441S (en) | 1997-11-12 | 1999-08-03 | Crown Cork & Seal Technologies Corporation | Plastic container |
| US5988417A (en) * | 1997-11-12 | 1999-11-23 | Crown Cork & Seal Technologies Corporation | Plastic container having improved rigidity |
| USD425424S (en) | 1997-11-12 | 2000-05-23 | Crown Cork & Seal Technologies Corporation | Plastic container |
| USD429151S (en) | 1997-11-12 | 2000-08-08 | Crown Cork & Seal Technologies Corporation | Plastic container |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20030715 |