FR2950282A1 - Handle integrated container manufacturing method, involves placing blank container at blowing temperature in mold, and blowing blank container at walls of mold to obtain final container with handle perpendicular to bosses - Google Patents

Abstract

The method involves preparing a preform by injection process, and blowing an initial container from the preform, where the dimensions of the preform are higher than dimensions of a final container. The initial container is heated to slacken residual constrains issued from blowing to obtain a blank container. The blank container is placed at blowing temperature in a mold with final profile and final dimensions. The blank container is blown at walls of the mold to obtain a final container with a handle perpendicular to bosses.

Description

METHOD OF MANUFACTURING BY BLOWING A CONTAINER WITH AN INTEGRATED HANDLE, CONTAINING OBTAINED

The present invention relates to a blow molding process of a plastic container, in particular PET (polyethylene terephthalate), with an integrated handle. The invention also covers the container obtained by the implementation of this method.

As soon as the volume of the containers is large beyond 1.5 liters to give an idea, it is necessary to facilitate handling by consumers to provide a handle. In the distribution, especially for mineral water, the packaging consists of several bottles grouped in pack of 6 bottles generally.

This pack consists of a plastic film itself provided with a gripping handle in the form of a transverse band attached to said enveloping plastic film. This has been made possible by the lightening of the containers themselves, made of PET, incommensurate with the weight of the glass containers.

It is nevertheless noted that each bottle has no means of grip while the containers themselves, if they have lost weight compared to the glass, have also lost the rigidity that characterizes the glass, making it more delicate grip. In fact, it is found that the bottles up to 1.5 liters capacity are manipulable while from 2 liters in particular, there are real problems of handling and handling, making difficult the payment and especially the dosage of the quantity paid.

One solution for improving the handling of large volume bottles is to have a handle on each bottle. Thus, containers with attached handles are known, these containers being bi-material, the container itself being made of PET or polypropylene.

These handles can be manufactured completely dissociated and reported at the end of manufacture on said bottle by clipping for example around the neck. In this case, the pouring aid is quite small because the possibilities of fixing points are limited to the neck so that such a clipped handle gives a help to the grip but a relatively limited assistance to the payment. The advantage of such a handle reported is not to disturb the manufacture of the container itself. These handles can also be made independently and reported in the extrusion blow mold so that the connecting means of said handle are secured to the container itself during the blowing operation and therefore during inflation of the container. The result is satisfactory from the point of view of gripping and aid pouring since the handle can be placed at a suitable point to take into account the center of gravity when pouring when the container is full and therefore when it is the most difficult to handle. The disadvantage is the difficulty of manufacture caused by the presence of the handle. The handle must be positioned in the mold as the preform that will be blown. bu makes different temperatures, different materials and the fact that the handle is static and the material of the preform is expanding, the settings are complex. The result of this overmoulding must lead to sufficient mechanical strength and certain when pouring the contents of the container.

This often results in the presence of a quantity of additional material for the manufacture of the container in order to be sure to have enough material to the right of the handle and thus achieve the desired mechanical properties.

The final container obtained is therefore heavier because of the handle but also because of the increased thickness of the wall itself. When the containers are made by extrusion / blowing, it is much easier to generate a handle during the production steps, the material being polyethylene and the amount of material being much larger, therefore the final weight is much larger. Indeed, at the extrusion outlet, the parison to blow is of a diameter greater than that of the neck of the container. This parison is even blown out of the die to increase this diameter. As a result, the container has a diameter such that the parison comes into contact with the walls of the mold. This mold is made in a special way so as to have protruding studs. Therefore, when the mold is closed, the pads provide a weld locally, walls vis-à-vis the parison. This welding is obtained because the material is still hot and allows a material weld material at this temperature.

Simultaneously and preferably, it is provided a pre-cut so as to allow removal of the double wall thus welded and generate a handle. Furthermore, in addition to the pre-cut welded zone of the handle, by the very fact of the extrusion / blow molding technique, it is also necessary to proceed with the elimination of the other pre-cuts from the shoulders and the collar as well as from the bottom, also pinched / welded, this evacuation being simultaneous to the outlet of the container out of the mold. Containers with a large volume, greater than 1.5 liters, can be obtained by extrusion / blowing.

In the case of injecting / blowing from PET, using a preform to be introduced into a mold whose diameter is necessarily smaller than that of the neck, this preform can not be likened to a parison. In addition, the technologies for obtaining preforms do not make it possible to obtain bodies that look like parisons. The thicknesses to be injected would become too small and impossible to obtain. There is therefore a demand to be able to produce in injection / blowing containers of large volume, that is to say greater than 1.5 liters, with a handle.

The technology used would not, even if it is possible to make a handle, to ensure a weld because the temperatures reached during the process do not allow the welding of the material on itself. Welding should be done with other technologies such as ultrasound. Another solution is not to make handles through but to make containers with means facilitating the grip without these means facilitating the grip are through handles: these handles are blind. Thus, the container is deformed to bring two walls facing each other locally, without welding them and thus forming a gripping zone.

Such an arrangement facilitates the gripping and is a definite improvement even if it is not a through handle allowing the partial passage of the hand, the blind handle thus formed for grasping and easy operation of said container. The present invention relates to a method of manufacturing a container by blowing from preforms, in particular by using PET, by generating a blind or through handle.

The method is now described in detail according to a particular embodiment, not limiting, with reference to the appended drawings, drawings in which the different figures represent: FIG. 1A: Final desired container, FIG. 1B: a cross-section along the line 1B- 1B, FIG. 2: Step 1 of the process, production of the initial container, FIG. 3: Step 2 of the process, production of the blank container, FIGS. 4A and 4B: detailed views of the mold in the open and closed positions, FIG. Step 3 of the process, production of the desired final container, FIG. 6: Additional step for producing a through-handle container. The method according to the present invention aims to obtain a Cfinal final container, having given characteristics, in particular Vfinal volume and a through handle. The volume is characterized in particular by the final length [-final and the final bfinal diameter. This container is represented in FIG. 1. The first step of the process according to the present invention consists in producing an initial Cinitiai container whose volume is Vinifiai, the length is linear and the diameter is binitial. See Figure 2.

Vinifiai is superior to Vfinal, Linitiale is superior to Lfinale and binitial is superior to bfinal • The manufacture of this initial container is made by injection blow molding, in known manner, from a PET preform for the particular example which is currently described. This preform is obtained by injection and has a finished neck, the dimensions and profile of the final container to obtain. Only the body dimensions of the final container are greater than those of the original container.

This first blowing leads to a thermally stable container at room temperature but which retains residual stresses related to the orientation of the PET and the mechanical deformation related to the first blowing. Moreover, it is also known that a heating ensures a release of these residual stresses, the blown container then having a tendency to return to its initial form of preform. These are residual stresses, so that when heating the initial container manufactured, the dimensions are reduced but without finding the size and profile of the preform.

Indeed, the blown PET, bi-oriented, is stable unless it is raised to a temperature above the glass transition point Tg of the material. If the material is carried beyond this temperature, the polymer chains immobilized by the cooling following the mechanical transformation of the blowing are released and the chains can be re-orientated as they were initially. This phenomenon is known as the PET memory. Thus, after heating, a blank container Cébauche, volume Vébauche less than Vfinal with a length Lébauche, and a diameter Débauche. See Figure 3.

It is noted that Lebauche is close to Lfinal while Débauche is smaller than Dfinal but greater than the diameter of the preform. This blank container can be likened to a parison, such as that used in the case of extrusion / blowing of PE described in the preamble of the present description, but with a finished neck since it is not concerned with blowing. The neck is left projecting, immediately above the mold, during the blowing phase. In addition, the shape of the blank container is cylindrical and the container is closed bottom.

This step is called recovery. Caloric intake to obtain this release of stresses after blowing is relatively low and very fast. This caloric intake can be made from a hot air flow or radiant panels, for example.

As a result, immediately after the first calorie intake, the initial blown container is transformed into a blank container. If the caloric intake is continued, the dimensions of the blank container remain unchanged since all the residual stresses are released but the temperature of the material increases.

The method therefore provides for heating the blank container to a temperature making it suitable for deformation, in particular for blow-molding. In this case, for PET, this deformability temperature can be located at a temperature above 150 ° C.

The blank container brought to deformability temperature CébaucheT is introduced into a mold 10. See Figures 4A and 4B. This mold 10 comprises an interior volume to the profile and the exact dimensions of the final container to obtain, the withdrawal near the material. This mold has an upper portion 12 adapted to receive the neck of the blank container. In addition, in the preferential embodiment chosen, a double boss 14-1 and 14-2, one on each part of the mold, intended to bring two local zones Z1 and Z2 closer together, facing each other, are provided. of the draft container brought to temperature. These two areas are not juxtaposed. These two closely spaced areas thus leave a passage 16 in the blank container. Once the closed mold, blowing air is introduced under pressure into the neck of the container, sealing, in known manner, the container swelling so that its wall comes into contact with the walls of the mold. This is the second blow phase. During this second blowing phase, the two bosses prohibit local deformation, zones Z1 and Z2 remaining in contact.

This produces a final container of shape and dimensions sought with a handle, in this case, one-eyed. See Figure 5. The cooling of the container freezes both the shape and dimensions, always taking into account the calculated shrinkage of the material, taken into account for manufacturing. This provides the desired container with blind handle.

It is noted that the blowing temperature is lower than that which would be necessary to obtain a weld of the material on itself. The soul Z1 / Z2 is not welded. The handle has been located on the container at a given location but it can be positioned anywhere in the container as needed.

The bosses are then arranged appropriately. The bosses can be reduced to a single boss or several to give a particular profile to the handle without changing the spirit of the invention. Similarly, the mold has been shown according to a particular embodiment but it can also be closed by a translational movement and not by a pivoting jaw movement. The present invention also makes it possible to obtain a container with a through handle as shown in FIG. 6. In this case, it is necessary to have a complementary step of welding the two zones Z1 and Z2, for example by ultrasound, to form a solid core. followed by a cut 25 of the core 18 full with removal of this cut portion, maintaining the seal of the handle. This gives an open handle.

According to an improvement of the invention, one can control the dimensions of the container after the initial blow, during heating to release the initial constraints, in order to have a blank container of desired dimensions, especially close to the final container.

For this purpose, it suffices during the stress release phase, simultaneously with the heating, to maintain an internal pressure in the container. The control of the internal pressure allows a control of shrinkage or "shrinkage" in terms of trade. The pressurization is made possible for example by sealing a source of air under pressure on the rim of the container. In this case, the dimensions of the blank container may be kept close to the dimensions of the final container. The second blow is then limited in expansion.

Claims (5)

REVENDICATIONS1. A method of manufacturing a final polymer container having a profile and final dimensions and a handle, characterized in that it comprises the following steps: preparation of a preform by injection, said preform having a finished collar, first blow molding an initial container from said preform having dimensions greater than the dimensions of the final container, heating said initial container to release the residual stresses resulting from the blowing to obtain a blank container of smaller dimensions than the final container, further heating up in that the blank container is at a temperature at least equal to that of the blowing temperature, placing the blank container at blowing temperature in a mold with a final profile and with final dimensions, comprising at least one boss on each part, closure of the mold for gripping said blank container by its bosses on at least two zones Z1 / Z2 facing, and second blowing the blank container thus pinched to press the blank container to the walls of the mold to obtain a final container with a handle to the right of the bosses. 2. A method of manufacturing a final container according to claim 1, characterized in that the two zones Z1 / Z2 undergo a heat treatment to weld them to form a solid core, and in that one cuts this soul full to generate a through handle. 3. A method of manufacturing a final container according to claim 1 or 2, characterized in that during the step of heating the initial container to release the residual stresses resulting from blowing, maintaining a pressure in the container to control the loosening constraints and shrinkage and ultimately the dimensions of the blank container. 4. A method of manufacturing a final container according to any one of the preceding claims, characterized in that the blank container is of dimensions close to those of the final container. 5. A method of manufacturing a final container according to any one of the preceding claims, characterized in that the polymer is PET.