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Patent Searching and Data


Title:
METHOD FOR MANUFACTURING CONTAINERS FOR THE TREATMENT OF LIQUIDS FOR FOOD USE
Document Type and Number:
WIPO Patent Application WO/2005/123602
Kind Code:
A1
Abstract:
The containers of the invention comprise a generally cylindrical intermediate tubular shell (2) and two opposing endpieces (3, 4) for its upper and lower closure. The manufacturing method of the invention comprises the following operative steps: separately preparing said shell (2) by obtaining it by cutting section from a commercial extruded tube of indeterminate length, separately preparing said two endpieces (3, 49 from a plastic material generally compatible with that of said shell (2), closely fitting said two endpieces (3, 4) to the opposing ends of said shell (2), and joining said endpieces (3, 4) and shell (2) together in a secure and sealed manner.

Inventors:
BONACINI CLAUDIO (IT)
Application Number:
PCT/EP2005/005709
Publication Date:
December 29, 2005
Filing Date:
May 24, 2005
Export Citation:
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Assignee:
AQUA S P A (IT)
BONACINI CLAUDIO (IT)
International Classes:
B01J47/02; B29C65/00; B29C65/02; B29C69/00; C02F1/42; B29C65/20; (IPC1-7): C02F1/42; B29C69/00
Foreign References:
US4382862A1983-05-10
US5006246A1991-04-09
Other References:
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 11 26 December 1995 (1995-12-26)
PATENT ABSTRACTS OF JAPAN vol. 011, no. 124 (C - 416) 17 April 1987 (1987-04-17)
PATENT ABSTRACTS OF JAPAN vol. 008, no. 145 (C - 232) 6 July 1984 (1984-07-06)
Attorney, Agent or Firm:
Corradini, Corrado (Reggio Emilia, Reggio Emilia, IT)
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Description:
DESCRIPTION METHOD FOR MANUFACTURING CONTAINERS FOR THE TREATMENT OF LIQUIDS FOR FOOD USE

TECHNICAL FIELD The present invention relates to a method for manufacturing containers typically intended for the treatment/conditioning of liquids for food use. The scope of the invention also includes the containers obtained by said method. A typical application of the invention is to produce containers of high capacity (at least some tens of litres), for containing means of known type suitable for the treatment of water (by filtration, osmosis, ion exchange, etc.). More particularly, a typical use of the containers of the invention is to soften water by passing it though ion exchange resins.

PRIOR ART With particular reference to said water softening, plastic containers substantially in the form of a cylinder and of several litres capacity are known, consisting of a generally cylindrical hollow casing intended to contain the ion exchange resin, and provided with end service openings The actual body of the container is produced in one piece by blow- moulding a hollow synthetic preform formed from a suitable synthetic material such as high density polyethylene of food quality. The body is then covered externally with a convenient layer of glass reinforced resin to provide it with the necessary strength, considering that such containers are required to be subjected to tests at fairly high pressures (up to 30 bar), as is well known to the expert of the art. The aforedescribed manufacturing method has proved unsatisfactory at least for the following reasons. Firstly for the fact that the container manufacture is relatively lengthy and complex, and hence relatively costly. Secondly because the container, once it becomes obsolete, cannot be recycled, being formed of three materials, specifically polyethylene, glass fibre and the application resin, which are physically inseparable and chemically incompatible, and hence unusable for other uses.

DISCLOSURE OF THE INVENTION The main object of the present invention is to provide a method able to overcome the aforesaid problems. Said object is attained by virtue of the characteristics defined in the claims. In a totally general sense, to attain said object the containers for the treatment of liquids for food use are produced from a single plastic material, preferably high density polyethylene of food quality, if the containers are to be used for water softening. The container presents a structure of classic type, i.e. comprising an intermediate cylindrical shell as its central component, provided with two opposing endpieces, said shell and said endpieces being prepared separately according to the invention and then securely joined together. In preparing the shell the invention starts from a plastic component normally available commercially, such as an extruded polyethylene tube used for water pipes and connections, the endpieces being prepared from virgin plastic material compatible with that of the shell and shaped by a usual moulding system, for example injection moulding. After said preparation, said endpieces are fitted to the opposing ends of said shell and fixed thereto, in particular by simple hot joining. All objects of the invention are attained by virtue of the aforesaid solution. In this respect, the manufacture of a container such as a casing for a water softener is relatively faster and less complex that that of the known art described in the introduction, hence correspondingly more economical. It also requires much less complicated and costly equipment or plant. Moreover as the container consists of a single-component material, once it has become obsolete it can be recycled practically without problem, for example ground and fed to other applications.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristics and the advantages of the method of the invention will be more apparent from the ensuing detailed description given with reference to the accompanying drawings, in which: Figure 1 is an interrupted exploded section showing the constituent elements of a container of the invention prior to assembly. Figure 2 shows the upper endpiece of Figure 1 on an enlarged scale. Figure 3 shows the lower endpiece of Figure 1 on an enlarged scale. Figure 4 is a partly sectional elevation showing the elements of Figure 1 assembled. Figure 5 is a section through a container in accordance with an alternative embodiment of the invention. Figure 6 is an enlarged section on the line Vl-Vl of Figure 5. Figure 7 is an enlarged detail of Figure 5.

BEST MODE FOR CARRYING OUT THE INVENTION Said figures show a generally cylindrical container indicated overall by the reference numeral 1 in Figures 1 and 4. The container 1 is of plastic, in particular formed of a single-component synthetic material, as defined hereinafter. In the illustrated example the container is of a shape typically suitable for use as a casing for a water softening means, after applying required elements and accessories, which are not shown for simplicity and because they do not form a characterising part of the invention. Of importance however is the manner in which the container 1 is manufactured. As can be seen, it comprises a cylindrical shell 2 of constant thickness and of circular cross-section, an upper endpiece 3 of generally hemispherical shape with an axial service hole 30, and a lower endpiece 4 also of generally hemispherical with an off-centre service hole 40. Said shell, upper endpiece 3 and lower endpiece 4 are of the same synthetic material, which in the illustrated example is of food quality, such as high density polyethylene. The shell is prepared from a usual commercial extruded polyethylene tube for water pipes and connections. On preparation, care must be taken to choose a tube having a thickness and diameter suitable for the use of the container 1 , said shell 2 being obtained by cutting a section from said tube. The upper endpiece 2 and lower endpiece 4 are formed by moulding, in particular injection moulding, food quality virgin high density polyethylene. After said forming, the upper endpiece 3 presents a transverse circular edge 31 generally shaped and dimensioned as the respective abutting upper end edge of the shell 2 (see Figure 2). A short distance from the outer limit of said edge 31 there is an uninterrupted descending rim 32 which extends a certain distance beyond this edge. Likewise, as can be seen in Figure 3, the lower endpiece 4 is provided with a transverse circular edge 41 generally shaped and dimensioned as the respective lower abutting end edge of the shell 2, beyond the outer limit of said edge 41 there being provided a continuous rising rim 42 extending a certain distance beyond this edge. Finally, on the opposite side to said rising rim 42 there is provided a continuous descending skirt 43 which extends beyond the base of the lower endpiece 4, where it forms a resting and support foot for the container 1. The finished container has the form illustrated in Figure 4, determined by the stable bonding of said shell 3, upper endpiece 3 and lower endpiece 4. For said bonding the upper endpiece 3 and lower endpiece 4 are associated with the upper and lower ends of the shell respectively, these ends being enclosed by the respective rims 32 and 42. While maintaining said three elements 2, 3, 4 conveniently pressed together, they are hot bonded or welded together by a welding operation typically known as hot plate welding. The weld seams which form during this stage are hidden by the rims 32 and 42 as can bθ seen in Figure 4. The merits and advantages of the invention are apparent from the aforegoing and from an examination of the accompanying figures. Figure 5 shows an alternative embodiment of the previously described container 1 , by which said container 1 is particularly suitable for use as a water softening means. In particular, the lower endpiece 4 of the container 1 in question is completely closed, the service hole 30 of the upper endpiece 3 being coupled to a distributor device 33 (indicated by dashed lines) comprising a conduit 34 of annular cross-section for entry of the water to be softened, and a central conduit 35, coaxial with the conduit 34, for exit of the softened water. In detail, the exit conduit 35 is joined to a tube 36 connected to a grille piece 37 through which it draws the softened water from the bottom of the container 1 (said tube and grille piece also being indicated by dashed lines). As shown in Figure 5, the container 1 comprises two distributor baffles 5 and 6, which separate its interior into three separate chambers positioned in succession, of which Sn upper chamber 10 communicates with the entry conduit 34, an intermediate chamber 11 for containing ion exchange resins, and a lower chamber 12 communicating with the exit conduit 35 via the grille piece 37 and the tube 36. In detail, each distributor baffle 5, 6 comprises a central hollow body 60 to be traversed by the tube 36, and a separator disc 61 for separating two adjacent chambers. The hollow body 60 of the upper baffle 5 is coupled to a cup member 7 which, sealed at the base by seal means interposed between the cup member and the tube 36, remains contained within the interior of the upper chamber 10; said cup member 7 being arranged to collect the water to be softened originating from the conduit 34, and to feed it into the chamber 100 through a plurality of lateral slits 70. The hollow member 60 of the lower baffle 6 is shaped to define a socket to be coupled to the tube 36 and to the grille piece 37, which hence remains contained within the lower chamber 12. As shown in Figure 6, the separator disc 61 of both the distributor baffles 5 and 6 is provided with ports 62 disposed radially about its central axis, they being closed by a mesh 63 to retain the ion exchange resins in the intermediate chamber 11 , but to allow the water to flow freely and distribute itself uniformly within the chamber. In this manner, during a normal operating cycle of the water softener, the water to be softened enters the upper chamber 10 under pressure, passes into the intermediate chamber 11 in contact with the ion exchange resins which decrease its hardness, then collects in the lower chamber 12 and finally, being under pressure, rises through the tube 36 to leave the container and reach the user. During a resin regeneration cycle, the container 1 is traversed not by the water to be softened, but by salt water, which takes the same path as that previously described, but is finally discharged. Constructionally (see Figures 6 and 7), the distributor baffles 5 and 6 consist of a single piece shaped to provide said hollow member 60 and separator disc 61 , and constructed of the same plastic material as that used for the shell 2, the upper endpiece 3 and the lower endpiece 4; the mesh 63 is a disc-shaped mesh, concentric with the disc 61 , which is incorporated into the interior of this latter by being interposed between two layers of synthetic material. In particular, the body of both distributor baffles 5 and 6 is formed by injection moulding, by inserting the disc mesh 63 into the mould, before moulding. On assembling the container 1 , the distributor baffles 5 and 6 must be installed before welding the shell 2, the upper endpiece 3 and the lower end piece 4 together. In the illustrated example, the upper baffle 5 is coupled to the upper endpiece 3, while the lower baffle 6 is coupled to the lower endpiece 4. In this respect, as shown in Figure 5, the upper endpiece 3 is provided with a perimetral seat 38 provided in proximity to its lower edge 31 , to house the baffle 5; likewise the lower endpiece 4 is provided with a perimetral seat 44 provided in proximity to its upper edge 41 , to house the baffle 66. However it should be noted that the distributor baffles 5 and 6 could also be coupled to the shell 2, each in correspondence with a respective end thereof. ! The upper endpiece 3 and lower endpiece 4 are then fitted to and securely bonded to the shell 2, in the previously described manner, to obtain the container 1 as shown in Figure 5. The substantial merit of this container 1 lies in the fact that the distributor baffles 5 and 6 enable uniform distribution of the water to be softened, or of the salt water, within the volume of ion exchange resins. In this manner, said resins are properly utilized, so increasing the life of the softening means and requiring lesser use of salt water for regeneration, resulting in lesser salt consumption and lesser environmental pollution due to discharge of the salt water.