NL8400040A - METHOD FOR MANUFACTURING CONTAINERS - Google Patents

Description

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Method for manufacturing containers.

The present invention relates to methods of manufacturing containers of thermoplastic polymeric materials. The methods involve the use of multifarious container components 5 which are spliced together to form an end container.

The present invention mainly relates to the manufacture of containers and more particularly involves methods of making plastic containers from multifarious components. Conventional container manufacturing methods mainly involve molding metal, bottle or composite paper materials into containers. Others conventional techniques involve molding plastics into container shapes. The present invention is directed to the field of technology related to plastics and more particularly to polymers such as polyesters and polyolefins. The containers made with the processes disclosed here replace those made with the conventional plastic molding technique as well as those with glass, metal and paper.

In the conventional manufacture of plastic bottles, a bottle can be formed by one of several methods. One such method is to form a preform or mold (parison) by injection molding a molten plastic material into a mold and allowing it to solidify. This press mold is then placed in a blow molding device that uses a combination of heat, air pressure and mechanical stretching means to expand the press mold into a final bottle.

Essentially, this two or three step process is very lengthy and expensive due to the time and equipment required in its manufacture as well as the large amount of energy input into the polymer. The melting of the polymer 35 into the injection forms the compression mold with subsequent cooling and then requires a required reheat to the 8400040. Blow-molding a large amount of heat input.

An alternative method of manufacturing plastic containers is the direct injection molding technique in which the finished bottle design is molded into a single mold and a liquid molten polymer is injected directly into the mold to form a finished bottle. On this design, although it eliminates the dual heat input of the performing process, it has the drawback that no orientation of the polymer is obtained and the resulting bottle is structurally very weak. Also, because the lack of orientation in the polymer is a very low barrier to the entry of oxygen and the exit of CO2

A third alternative method of forming thermoplastic containers is to extrude a tubular press mold and while the tubular press mold is still in a molten state, the mold is enclosed in a mold and blow molded into a finished bottle. This has the drawbacks that very little orientation is achieved in the bottle and the bottle thus has weak areas in the bottom section where the seam is formed during the blow molding process.

The present invention aims to avoid the drawbacks of the known method of forming thermoplastic bottles and other components by applying processes in which the individual components can each be formed in the most economically available manner, yet each greatest benefits of its thermoforming process. The components are then put together in a single strong, aesthetically pleasing container by rotary welding. In a manner according to the invention, a container is formed by thermoforming a top section, which has a threaded neck region and cylindrical wall edges, thermoforming at a bottom section, which has sliding characteristics into each other, and extruding a cylindrical body portion to which the top and bottom sections 8400040 - 3 -. . ; i: be rotational welded.

To clarify the invention, an exemplary embodiment will be described with reference to the drawing.

Herein: fig. 1 shows a partial cross-sectional side view of a container manufactured according to the present invention; FIG. 2 is an enlarged cross-sectional view in side view of the top portion of the container of FIG. 1; Fig. 3 is an enlarged side cross-sectional view of the bottom section of a container; FIG. 4 is an enlarged top cross-sectional view of the drivable cam ring of the top section of FIG. 2; Fig. 5 is a side cross-sectional view of a container bottom stacked on a container top; Fig. 6 is a cross-sectional view of the three-layer thick wall of the container.

With reference to Figure 1, a bottle-shaped container 101 is shown in partial cross-section in side view. Bottle 101 includes a generally cylindrical central section 102 formed in the form of a cylindrical tube, which is assembled for this purpose with an upper bottle or top section 103, and a lower closure or bottom section 104.

The upper section 103 mainly consists of a lightly tapered substantially cylindrical rim section 105, an inwardly-going shoulder section 106, and an upper threaded cylindrical neck section 107, which has helical cap threads 108 formed thereon. A dual purpose ring 109 is formed around the neck section 107 and projects radially outwardly therefrom. The purpose of the ring 109 is to provide a filler ring to suspend the bottle from the filler during the filling of the contents into the bottle. Ring 109 also includes a set of circumferential drive cams formed thereon to allow connection of the top section in a mandrel for rotary welding 8400040 4 V - 4.

The central section 101 is a substantially cylindrical tubular section preferably formed by extrusion or coextrusion in the final form. The cylinder is cut to length by means such as a hot knife or a water laser to form the desired capacity bottle. Although the embodiment illustrated in Figure 1 shows the wall section of the central hull section 102, which is made of a single layer of polymeric plastic, in one embodiment of the invention, a cylindrical hull section 102 was formed by coextrusion through a cylindrical coextrusion die into a multi-layered cylindrical hull section. as can be seen in figure 6. Preferably, the layers of polymer used are three or five in number and include FDA-tested polymeric inner and outer layers and a central barrier layer formed of a known barrier polymer such as ethylene vinyl alcohol (EYAL) to prevent the penetration of prevent oxygen and the loss of carbon dioxide from the container through its wall. In addition, there may be additional layers between the barrier layer and the outer and inner layers, of a material such as CXA which is an adhesive for binding the polymer to the barrier. CXA is an adhesive manufactured by du Pont Chemical Company.

The bottom portion 104 substantially comprises a schematic circular type closure member having a relatively flexible central portion 110, a diagram area 111, and an upwardly directed U-shaped rotationally welded flange 112 around its periphery. It should be noted that the top portion 105 has correspondingly downwardly U-shaped rotationally welded flange 113 in accordance with the upwardly directed flange 112 of the bottom member 104. The U-shaped flanges 112 and 113 are sized to receive in fixedly mounted therein connected the cylindrical body portion 102 of the container. It may be preferable that an intermediary application be arranged between 8400040-5.

flange regions 112 and 113 and the cylindrical body section 102. This will provide fusion heat when the three container sections are joined by rotary welding. As mentioned previously, the container 101 is made of a poly-5 more selected from one of the polyesters or polyophins. More specifically, one of its embodiments, the container 101 was made of polymeric polyethylene terephflate (PET). This polymer has been accepted by the FDA for food products and is of particular benefit to containers due to its clarity, strength and barrier properties. PET, too, is particularly responsive to strengthening by the manner of orienting the structure at its orientation temperatures when stretching the polymer. The central body section 101 is preferably formed of either a solid PET material or may be formed by circular coextrusion dies. In a preferred embodiment, five layers of polymer can be coextruded into a cylindrical tube. The outer layer can be PET then a layer of adhesive, such as barrier material such as saran, Barex, or EVAL, can be used. Then a layer of adhesive and an end-inner layer of PET could follow. These materials can be co-co-extruded into a single multi-layer cylindrical tube using centerless dies disclosed in US patent 4 249 875 issued February 10, 1981, from Hart and Rutledge, for the coextrusion apparatus and method of production. of multi-layer thermoplastic pipe assigned to the assignee of the present invention. Said patent is hereby incorporated by reference to the present application.

Referring to Figure 4, an axial cross-sectional view of the upper portion of bottle 101 taken along line 4-4 of Figure 1, this figure more particularly illustrates the structure 35 of the crimped washer 109. In Figure 4 the neck portion 107 is shown in cross-section, to which is integral an outline filler ring 109. Washer 109 protrudes outwardly from the surface 107 a substantial distance. A set of symmetric rotationally welded cams 114 are formed on the outer periphery of the ring 109 and project radially outwardly therefrom. The cams 114 are especially adapted to connect to a rotationally welded mandrel to apply the rotary motion to the top portion 105.

A slit 116 is cut through the wall of the flange 112 and the lower end of the wall 102. This notch is cut into the bottom edge of the container as a location slot for printing a label on the container and to ensure that when the container is placed in the additional package, for example, "a six-pack", the preferred area of the label will be in an externally visible location. This is an extremely important marketing aspect for the sales company that fills the packaging and sells it under its trademark. For example, beverage manufacturers are very interested that each container in the package has its main part of the trademark or sign so that when the package is placed in a supermarket, the eye-catching characteristics of the label are visible to the consumer . Thus, cutting notches 1T6 25 in the bottom edge of the container allows the filer to position the label in such a way that when the filled container is placed in the standard six pack, the slot can be used to orient the container during packaging so that the eye-catching portion of the mark extends forward into the package.

Alternatively, a locating means such as a cam or a protruding bump can be formed in the top section 103 rather than the notch 116 in the bottom edge 112. A protruding portion or cam could also be formed within the trough 11 of the bottom 104 , which could be visible from the side or top of the container 101. This particular embodiment of the location means 116 8400040-7 is the preferred form because of secondary packaging interests. The slot 116 allows for easy orientation of the bottle through a protruding lug in the secondary package, which can connect to the slot, thus providing an orientation of the bottle when displayed at retail. Likewise, connecting a location arm in the slot 116 can provide additional support of the container in the package.

Figure 2 shows a view of the upper portion 105 of the three-piece container before it is joined to the central hull section 102. This view illustrates the possibility of nesting or stacking the top sections 105. In Figure 2, a second top section 105 drawn in imaginary lines to indicate the possibility of stacking the top sections relative to each other. This is particularly important for the large-scale manufacture of containers. Many containers must be manufactured in one location and shipped to another location for filling. In the case of conventional one- and two-liter sizes PET bottles, they are formed essentially from a single piece and shipped empty to their final filling point. Normally, a truck or railway wagon is loaded to its capacity with single-piece bottles being shipped at about 1/20 of the normal shipping weight although the entire ship volume is filled with empty containers. So the shipper mainly pays for the air shipment. Using the present invention, the shipper can ship components of bottles that are stacked as shown in Figures 2 and 3 and thus greatly enhance shipping efficiency. Figure 3 illustrates the possibility of stacking the bottom sections 104 by indicating a bottom section 104 partially in cross section and an additional bottom section 104 illustrated in imaginary lines in a nested or stacked position.

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In Figure 2, one can see the shipping space savings achieved using the present invention. If one consider the distance that the imaginary representation 105 protrudes from the fixed representation 105, it can be seen that the top portion occupies only an additional space of about one third of that of the original space occupied by the top portion.

Thus, the bottle manufacturer can ship a larger number of top portions 105 stacked on top of one another, saving about two-tenths of the normal shipping space. Likewise, the bottom portions 104 can be stacked to obtain additional space savings.

Following the stacking or nesting of the top and bottom sections, the use of a coextruded cylinder for the central section of the container allows the bottle manufacturer and filler to manufacture the central section 102 at the filling site thereby saving on shipping costs for the cylindrical tubes.

Thus, for the central sections, the shipper only has to ship in 20 bulk polymer pallets, which is very efficient in space utilization and which can then be easily converted into cylindrical tubes by cylindrical extrusion at the filling site. Thus, the present container design offers the great advantage of a great reduction in shipping costs for empty containers, as well as increasing the strength and other characteristics of the finished container built from the rotationally welded construction.

Figure 5 illustrates an alternative embodiment of the bottom portion 104 of the three-piece container. In Fig. 5, a bottom section 204 is formed which has the circumferential U-shaped rotational weld flange 212 surrounding it and a bending section 211 positioned within the flange 212.

The central section 210 includes a cylindrically raised cap-shaped receptacle section 210 adapted to receive the top neck portion 107 of the bottle top below. The neck 8400040 - y portion 107 has a cap 115 threadedly attached thereto. The lower shoulder portion 213 of the receptacle portion 210 is sized for an adjacent connection to the bottle washer 109 placed below the bottle to which the bottom 24 is added. Thus, the shaped receptacle 210 in the bottom 204 allows the filled containers to be stacked on the storage shelf or showroom shelf in a stacked form that is stable and attractive so as to display the products. A drawback of the known containers such as glass bottles and the press-mold type plastic bottles is that they are highly labile and cannot be stacked without placing storage shelves between each layer of containers. Thus, if the retailer, such as a supermarket owner, wants a multi-layer storage of the products, expensive and time-consuming storage shelves must be placed between each layer of containers. With the present invention, using the receptacle 210 of the cylindrical bottle in the bottom of each container, the neck portion 107 containing a cap 115 may project upwardly into the bottom of a filled container and the weight of the filled container can be carried by the heavy, strong washer 109 of the containers immediately below.

An incorporated application would clearly be adaptable to the present invention for forming cans rather than bottles.

Although the top portions 103 and the bottom portions 104 and 204 can be formed by the conventional means such as injection molding, it would be appreciated that more innovated means can be used to form these sections. For example, in copending patent application Serial No. 394 382 filed July 1, 1982, by J. Hahn of Granville, et al., "Device for forming biaxially oriented thermoplastic articles" assigned to the assignee of the present invention, a device for 8 * 00040

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- 10 - Thermoformed articles such as container tops and bottoms "disclosed. This device is particularly attractive to use in the present invention because of the advantages obtained by this thermoforming technique and device. In the Hahn et al. Application, either a single sheet or a multi-layer sheet polymer is heated to a temperature above the orientation temperature and medium pressure air supply is used to press the sheet material down onto a preformed shape and thus creates a press form. A certain amount of cooling comes on the preformed shape and the polymer is lowered in temperature to its orientation area. At this time, a wave of air under high pressure blows through the preformed mold and stretches the sheet in its final configuration in the final mold, and simultaneously the finished article is formed, thereby optimizing the article at an optimum -axial orientation to obtain stretched. The use of Hahn's device could provide tops and bottoms for the present container, which are sufficiently oriented to obtain optimum strength and barrier characteristics. Thus, when using the Hahn's device, as suggested as a conventional injection molding technique, additional strength can be obtained by orientation that cannot be achieved in the injection molding system. Thus, one can use coextruded sheet materials to obtain a multi-layered top or bottom comprising a barrier layer of polymer "sandwiched" between two layers of regular container polymer such as PET. The aforementioned patent application 30 of Hahn et al. S.N. 394 382, is hereby introduced by referring to it in its entirety in the present application.

Typically, a beverage or other type of container is formed using the three sections disclosed in Figures 2 to 5. More particularly, a top section 105, which is formed by injection molding or embossing (thermal formation) in the 8400040-11 solid phase has a downwardly formed rotationally welded flange 113 thereon and is placed in a rotation axis. A cylindrical wall section 102 formed by extrusion or blow molding is placed in the central mandrel 5 of the rotary welder. A bottom portion 104 or 204 having an upwardly formed rotationally welded flange 112 is disposed in a lower rotation axis. Preferably, the central rotating mandrel containing the central rorop section is a stationary mandrel, and the top and bottom mandrels 10 are adapted for pivoting. After the three holders are placed in their respective mandrels, the up and down mandrels have delivered rotational energy to them to rotate rapidly relative to the central mandrel. While the top and bottom mandrels can be rotated in the same direction, they will preferably be rotated in the opposite direction to release the torque from each other. After reaching a pre-selected rational velocity, which has been determined based on the particularity of the polymer used and the value of mating the rotational welded flanges 112 and 113, the top and bottom sections become fast connected to the central section, pushing the walls of the central section into the U-shaped flanges thereby causing the plastic 25 to temporarily melt and flow together therein. This forms a firm, clean, hermetically sealing joint in the flanges 112 and 113 and a strong joint is thus formed.

Subsequently to the ring strength achieved with the rotationally welded joints at 112 and 113, which ring strength contributes greatly to the overall strength of the holder provided with the radially projecting shoulders as a result of the flanges 112 and 113, in a protected la-belzöne for the completed container. Essentially, these protruding shoulders at 112 and 113 may be referred to as "roll rings". When a label is applied to the center hull section 102 such as a glued label or an 8400040-12 printed label directly on section 102, rings 112 and 113 come into contact with rings on the adjacent bottles and prevent scratching and chafing of the printed label on section 102. This provides meaningful protection for the label, which is of primary significance to the retailer. Thus, the advantages of the present invention include a good nesting or stacking capability when the container components are shipped before the containers are assembled. A further advantage is the possibility of the retailer. A third advantage is to increase the ring strength obtained by inserting the rotation weld into the wall of the container and another advantage is the protruding roller rings which provide protection of the decorative labels on the containers.

Another particular advantage of the present invention is that it allows the manufacture of the different components by different methods to obtain the optimal characteristics for each particular component. For example, where the crests and bottoms have been described as having been manufactured with different techniques to provide the optimum strength and barrier characteristics and where the central section has been described as having been prepared with different techniques to provide improved orientation and barrier characteristics. -25, additional qualities can be achieved for the finished container. For example, the rotary welding at the top and bottom of the tubular central section provides increased ring strength for the entire container as well as providing a pair of parallel roll ribs to protect each tag attached to the central section. Furthermore, the provision of an extended central section provides a maximum surface area for receiving the advertising label for the food or beverage manufacturer filling the container. This is known as "optimizing the billboard space" on the container. The present invention provides more billboard space for 8400040-13.

Then the label uses any known type of conventional bottle holder to package drinks.

In addition to the optimal billboard space, the present invention also provides opportunities for enlarging the outer surface of the container for placing printed and / or painted labels. For example, when the central tubular section is formed by coextrusion, one of the layers of the coextruded cylinder, for example, the outermost layer, is made of a white opaque semi-porous material such as polystyrene, high impact resistant polystyrene, polyvinyl chloride or polypropylene, which provides a highly desirable surface for printing on it with bright vibrant label colors using conventional label printing methods.

The top portion 103 of the bottle can be formed from a clear tough material such as PET which is attractive to the consumer and provides a clear picture of the contents of the bottle. Likewise, for the bottom section 104, an optimum material can be selected to provide the desired container filler characteristics. A relatively inexpensive material such as polystyrene or high impact polystyrene could be used for the bottom portion 104 to reduce the cost of the finished container. All of these substitute materials naturally depend primarily on the compatibility with the rotary welding of the various components together. For example, the contact surfaces in the outer flanges of the top 103 and the bottom 104 must be compatible with the rotary welding of the outer and inner surfaces of the cylindrical wall portion 101. Those materials that are compatible with rotary welding are known to those skilled in the art and replacements can then be made accordingly.

While the foregoing description is related to bottle shaping using methods of the present invention, one may also use the techniques disclosed herein to form what is

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8400040 - 14 - referred to in the beverage and food industry as "one-time buses". In that case, instead of using a container with a top section T03, the container has a circular top section, which has a substantially flat top surface, such as can closing means. This top section 5 includes an opening sleeve that can be easily lifted and pulled to open the sleeve. This flat top section can be rotationally welded to the cylindrical central section 102 in place of the top section 103 of the present invention.

Thus, referring to the figures of the incorporated Fortuna application, the closures 101, 201, 301, and 401 illustrate that they are particularly suitable for use in closing beverage cans. More specifically, these closures would be highly desirable for use with the three-piece beverage container disclosed in this specification to form a one-time canister. Any of the aforementioned crests may be rotationally welded to the cylindrical tube of the present disclosure in place of the disclosed top portion 103. The manner of fastening the Fortunabus seals is substantially identical to the manner of attaching the top portion 103, for example, by the rotation welding of the bus body seal to the cylindrical body portion 102.

The Fortuna bus terminations mentioned above all offer the advantage of a U-shaped rotationally welded flange at the outer periphery compatible with the rotation-welding techniques of the present invention. Thus, it is understood that the closures disclosed in the incorporated applications are clearly adaptable to the present invention for forming cans rather than bottles.

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Claims (20)

A method of forming a container for packaging liquid products, said container having a barrier to gas transmission through its wall and comprising: 5. forming a top section of a thermoplastic plastic, having sealing means and a cylindrical wall section; - forming a cylindrical hull section of a laminated thermoplastic material, which is provided with at least one layer of strong plastic to which adhesive has at least one layer of barrier plastic; - forming a circular container bottom of a thermoplastic plastic; wherein said top, hull and bottom sections are formed from materials adapted for spin welding; and rotationally welding said top section and said bottom section to said hull section. 2. A method according to claim 1, characterized in that at least one of said top and bottom components is thermoformed by molding at a solid phase pressure. Method according to claim 1, characterized in that at least one of said top and bottom sections is formed by injection molding. 4. A method according to claim 1, characterized in that said hull section is coextruded in a multi-layer tube coextrusion, which has at least two layers bonded together. 5 PVC and polystyrene. A method according to claim 1, characterized in that said hull section is coextruded with a cylindrical coextrusion die in at least three layers, said three layers comprising an internal layer and an external layer of structurally strong thermoplastic material and a central layer and comprising a thermoplastic material, which exhibits low gas permeability. 8400040 -lb- 6. A method according to claim 1, characterized in that said top and bottom sections are made of a thermoplastic material selected from the group comprising PET, PETG, polypropylene, polythylene, A method according to claim 5, characterized in that said central layer is selected from the group comprising EVAL, PVCD, Saran and Barex. The method of claim 1, further comprising the step of orienting said central section for the step of said rotary welding step, by stretching said section, while heating said section to the orientation temperature of the thermoplastic material therein. 9. A method according to claim 1, characterized in that said container is a bottle and said top section comprises a threaded neck portion and a larger cylindrical wall portion. 10. A method according to claim 1, characterized in that said container is a jug having a relatively flat circular top section with a loop-open closure. A method of making a plastic beverage bottle, said method comprising: 25. injection molding a top section of a thermoplastic polymer, said top section having a threaded neck portion and a circular rim portion; - extruding a cylindrical tube section 30 of thermoplastic polymer; - cutting said central section to a predetermined length; - forming a circular bottom section having a flange thereon and adapted for rotary welding a said tube section; and - rotationally welding said top and bottom sections to said tubing section to form a beverage bottle. 84 0 0 0 4 0 - 17 - * 12. The method of claim 11, characterized in that said top section is formed with a downwardly projecting vorm-shaped rotationally welded flange thereon, and wherein said flange of the bottom section is an upwardly projecting ü -shaped flange. Method according to claim 12, characterized in that the extrusion step further comprises coextruding said cylindrical tube section into at least three layers comprising inner and outer layers 10 of a first thermoplastic material and a central layer of a second thermoplastic material between said first and second layers. 14. A method according to claim 12, characterized in that said extrusion step further comprises coextruding said cylindrical tube section in five layers comprising inner and outer layers of a first thermoplastic material, a central layer of a second thermoplastic material, and a layer of adhesive material between said central layer and each of said inner and outer layers. 15. A method of forming a thermoplastic container with a barrier, comprising: securing a plate laminated thermoplastic polymer, which has structurally strong polymer outer layers and an inner layer of a polymer with low gas permeability; - forming a container top and a container bottom of said plate; coextruding a cylindrical tube having 30 inner and outer layers made of a polymer compatible with said structurally strong polymer of said top and bottom, and a central layer between said inner and outer layers comprising a polymer with a low gas permeability; 35. cutting said co-extruded tube to a predetermined length; and - rotationally welding said top and bottom to said tube to form a complete container. 8400040 - 18 - * The method of claim 15, further comprising the step of forming said laminated sheet using a coextruded multi-layer sheet. 17. A method according to claim 15, characterized in that at least one of said top and bottom components is formed under pressure in the solid phase at its orientation temperature to increase its strength and barrier characteristics. The method of claim 15, further comprising the step of stretching said cylindrical tube at the orientation temperature of said tube polymer to increase its strength and barrier characteristics. 19. A method according to claim 15, characterized in that said outer layer of the tube contains a polymer, which costs little, has high opacity and has a good printability. 20. A method according to claim 19, characterized in that said polymer is selected from the group comprising polystyrene, high impact resistant polystyrene, polypropylene and polyvinyl chloride. 8 4 ö ö Q 4 0