Patent Application
20240208156
The invention is related to a fluid dispenser container comprising a transparent plastic container body and a bottom part joined by laser welding to the transparent plastic container body according to the preamble of claim 1, and a method for producing a fluid dispenser container according to the preamble of claim 16.
A fluid dispenser container with a plastic container body with a dispensing valve and a separate bottom part mounted to the plastic container body is known as plastic aerosol and produced by the applicant and sold to the market since several years. However, the main problem of known fluid dispensers of this type is that they are made of different resins or different resin families, i.e. the container body may be produced from PET, whereas the dispensing valve is made of sheet metal and the bottom part is made of engineering plastics, reinforced with glass fibres, filled with additives like carbon black and containing a rubber plug to close the package after pressurizing the container with a gas as an aerosol, air or the like.
EP 1 791 769 B1 describes an aerosol container for dispensing a pressurized product, which includes a body, stretch blow moulded from PET or like plastics material, said body having a shaped neck surrounding an opening, a collar, injection moulded from plastics material, snap-fitted to the shaped neck, and a dispensing valve attached to said neck and collar. The dispensing valve includes an outer flange with is formed of malleable material (e.g. aluminium) and which is shaped to fit about and be retained to said collar by being compressed therearound. The body 2 of the container includes a base or bottom part 6 and a neck portion 7, which are all integrally formed by stretch blow moulding PET from a preform. The collar 3 as a separate part is formed from plastics material by injection moulding and has on the inner surface an annular lip which can be snap fitted to an annular recess 9 of the shaped neck 7. The dispensing valve 4 is of a conventional type which is formed of metal malleable material (i.e. aluminium). The outer flange 11 is shaped to fit to the collar 3.
EP 1 943 165 B1 concerns an aerosol container for dispensing a pressurized product, including a body 2, formed of PET or like plastics material, which body has a shaped neck 7 about an opening 10, a collar 3 which straddles the external and internal walls 33, 34 of the opening 10 to form a shaped lip 35 therearound and be attached to the body 2. The container further includes a dispensing valve attached to the collar 3, wherein the valve including an outer flange 11 formed of metal or malleable material (e.g. aluminium) and be retained thereto by compressing therearound.
WO 2017/112977 A9 describes a pressurized container system which comprises a container 1 provided by a cylindrical casing 22 with a neck part 23 with a pouring opening 24. The bottom side of the casing 22 is cut away and closed by a separate base part 21 by means of a connection 13. The container 1 is made of a plastic material which is biaxially stretchable and has a high intrinsic viscosity, which is characterized by a high pressure resistance. Especially, a heat set blow-moulding process is applied to obtain an accelerated crystallisation effect of the plastic material, i.e. hot-fill PET. Other materials as PET copolyesters with a high pressure resistance are mentioned. The container may also be made of polyamide, polysty-rene and COC. A base part 21 is attached to the container 1 by a joint, which may 25 be obtained by gluing, folding or welding, in particular laser welding induction welding or ultrasonic welding. Any further information about the kind of joint and how the joint is exactly made, is not described. In order to pressurize the container a closable valve is provided in said base part, which is of a so-called “umbrella plug” or a so-called two-stage “Nicholson plug”. These plugs are normally made from rubber.
Since environmental sustainability is becoming much more important, the compo-nents of such a fluid dispenser container should be made of similar material so that used containers can easily be recycled. Especially the materials used must be com-patible with established and commonly used in plastics recycling streams.
As an example WO 2015/061071 A1 describes an aerosol dispenser made from materials which can go into a single recycling stream having a single class of materials, defined by the Society of the Plastics Industry (USA), and particularly comprises exclusively Class 1 materials (PET) with no flammable product/propellant present. The production process of above mentioned aerosol dispenser is not described. Moreover, the base is integrally formed with the outer container, as is obvious from
The present invention, however, is specifically directed to a fluid dispenser container with a plastic container body with a dispensing valve and a separate bottom part mounted to the plastic container body.
Since the above mentioned pressurized container systems should withstand higher pressures, e.g. up to 20 bar, which have to fulfil regulatory and legal requirements e.g. DOT-, FEA and BS-Standards for plastic aerosols, it is very important that there is a secure and pressure-safe seal connection between the bottom part and the lower open-end of the container. The applicant has a large experience in producing plastic aerosols, i.e. high pressure containers since more as a decade and has made intensive experiences in connecting a separate bottom part to the a high-pressure container by laser welding. For a secure laser welding joint between the separate bottom part and the high-pressure container, which is made of transparent PET, the plastic material of the bottom part, which is e.g. glass fibre reinforced engineering plastic and is different from PET, is mixed with carbon black in order to absorb the laser light and to obtain a pressure-safe and break-proof weld between the bottom part and the pressure container. In some instances there are provided two parallel ring-shaped laser welds between the bottom part and the pressure container. Currently, the bottom part is made from glass fibre reinforced PBT (poly-butylenterephthalat) and 1% carbon black. The glass fibres are added to stop creep—under constant overpressure plastic tends to keep on stretching which would finally result in a balloon-shaped high-pressure container. The PBT used is impact modified, which means that it can absorb the impact as required in the regulatory drop test. Another aspect is the chemical resistance. Previously, polycarbonate (PC) was used, which is highly sensitive for many chemicals used in customer products. Besides this fact, PBT has much better gas barrier properties, which is essential for maintaining the pressurized gas.
At present there is no available method for laser welding a circular tube as the above-mentioned pressure container and a transparent bottom part, which is good enough to withstand the high forces and guarantees a high seal integrity.
It is an object of the present invention to provide a fluid dispenser container with a plastic container body with a dispensing valve and a separate bottom part, which are all made from the same plastic material, especially PET or PEN, and which fluid dispenser container can withstand elevated pressures under extreme performance requirements as drop test from 1.8 m at 18° C., etc. A further object of the invention is to provide a method of laser welding a transparent bottom part to a transparent plastic container body, in order to obtain a secure joint between the transparent bottom part and the transparent container body which creates sufficient strength to withstand impact and creep load.
This object is achieved by a fluid dispenser container with the features of claim 1 and by the method for producing such a fluid dispenser container with the features of claim 16.
In accordance with an aspect of the present invention the fluid dispenser container comprises a transparent plastic container body with an open end and a separate bottom part joined by laser welding to the open end of the transparent plastic container body, wherein the separate bottom part is made from the same transparent plastic material as the plastic container body and the separate bottom part is laser welded to the plastic container body by melting mating surface lines on the plastic container body and on the separate bottom part, whereas the heat to melt is created by a stationary laser means while the plastic container body has been rotated by rotating means at least over a full rotation or by a circularly movable laser means in at least a full circular motion while the plastic container is stationary.
In an advantageous embodiment according to claim 2 the plastic material of the transparent container body and of the transparent bottom part is PET, PEN or other plastic material from the polyester family thereof.
In a further advantageous embodiment according to claim 3 a piston for dispensing fluid is provided, which is made from a plastic material with a density lower as the density of PET.
In a further advantageous embodiment according to claim 4 the transparent bottom part has a ring-shaped outer rim and an inner cup which has a central passageway provided by a central cylindrical tube with an upper central hole.
In a further advantageous embodiment according to claim 5 the outer rim, the inner cup and the central tube have the same material thickness.
In a further advantageous embodiment according to claim 6 radial ribs between the central tube and an outer wall of the inner cup are provided, in order to strengthen the central tube against the outer rim.
In a further advantageous embodiment according to claim 7 lower supporting ribs between the outer rim and the inner cup are provided which are protruding obliquely from the inner wall of the outer rim to the lower part of the inner cup in order to provide large stability, reducing deformation from the outer wall under extreme conditions and a perfect circular cylindrical form with high precision of the transparent bottom part.
In a further advantageous embodiment according to claim 8 the transparent bottom part comprises an outer ring-shaped rim with a bottom part, radial ribs and a central passageway provided by a central tube with an upper central hole.
In a further advantageous embodiment according to claim 9 the upper central hole is bridged or domed by a cylindrical plug which is connected to opposite pillars protruding from the central tube.
In a further advantageous embodiment according to claim 10 a fill valve a closing element is mounted in the central tube which has a cuplike base part with an inner blind hole and a ring-cylindrical protruding rim, whereas on top of the base part an upper frusto-conical section with two opposing grooves is provided.
In a further advantageous embodiment according to claim 11 the closing element is made from PET, PEN or other plastic material from the polyester family thereof.
In a further advantageous embodiment according to claim 12 the central cylindrical tube has open ends on both ends and a movable closing element of an elastomeric material is provided within the central tube.
In a further advantageous embodiment according to claim 13 the closing element is designed as two stage Nicholson plug or as umbrella valve or as rope bung plug.
In a further advantageous embodiment according to claim 14 a pressure control device with a transparent high pressure container is mounted in the lower part of the plastic container body.
In a further advantageous embodiment according to claim a disc with a pressure control device made of a transparent material is welded to the inner wall of the transparent container to provide a high pressure chamber between the disc and the bottom part.
According to claim 16 the method for producing a fluid dispenser container is provided, wherein the transparent container body is made by injection stretch blow moulding from a preform and the bottom of the container body is cut-off to provide an open lower end of the container body, further the separate transparent bottom part is made by injection moulding in which molten plastic material is shaped in the desired form by multiple cavity moulds, and the separate bottom part is laser welded to the plastic container body by melting mating surface lines on the plastic container body and on the separate bottom part, whereas the heat to melt is created by a stationary laser means while the plastic container body has been rotated by rotating means at least over a full rotation or by a circularly movable laser means in at least full circular motion while the plastic container is stationary.
According to claim 17 it is advantageous, when a thin ring-shaped absorber layer is applied to the outer wall of the transparent bottom part and then joined by laser welding to the transparent container.
According to claim 18 it is advantageous, when the thin-lined absorber layer is applied by using inkjet technology.
According to claim 19 it is advantageous, when the melting heat is created by a laser equipment selected by the group diode, YAG or fiber lasers which typically work with an absorber coating on one of the two parts to be joined.
According to claim 20 it is advantageous, when transparent laser plastic welding (TLPW) is applied, in which a higher wavelength laser is used than the typical 808 nm or 980 nm infrared lasers used in through-transmission welding, such that some of the laser energy is still transmitted or passed through the transparent container body, but at this higher wavelength laser energy is absorbed through the separate transparent bottom part, in order to heat and plasticize the plastic material at the joint area between the transparent container body and the separate transparent bottom part.
According to claim 21 it is advantageous, when the laser means is sending a laser beam having a wavelength of 1900 to 2100 nm, preferably 2000 nm, which welds the transparent container body and the separate transparent bottom part without the use of absorber layers, whereas the melting heat is generated in the focus of the laser beam.
Further advantages can be derived from the description below.
The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:
In the figures the same reference numbers are used for the same elements, if not mentioned otherwise.
In
In
In the passageway 24 a fill valve 30 is provided which is shown in more details in
As further can be seen in
In
In order to join the transparent bottom part 13 and the transparent plastic container 12 the stationary laser for the production of the known fluid dispenser container 1 of
The diameter of the transparent bottom part 13 is slightly larger than the iinner diameter of the open lower end of the transparent container 12, so that the transparent bottom part 13 is press-fit into the transparent container 12 before it is welded.
The transparent bottom part 13 and the transparent container 12 are made from the same plastic material, preferably from PET, PEN or other plastic material from the polyester family thereof, and are joined by mating surface lines, whereas the melting heat is created by a laser equipment, which can be diode, YAG or fiber lasers which typically work with an absorber coating on one of the two parts to be joined. These lasers have a wavelength between 0.8 and 1.1 μm. A thin ring-shaped absorber layer is applied to the outer wall of the transparent bottom part 13 and then joined by laser welding to the transparent container 12. The thin-lined absorber layer is preferably applied by using inkjet technology which gives a good control and relia-bility on the distribution of the printed volume. Full opaque lines or dot printing can additionally be used. The objective for the recycling process is to use a minimum quantity of printing ink with carbon black. After laser welding the thin-lined absorber layer may partly disappear or fade away, so that a clear joint between the transparent container 12 and the transparent bottom part 13 is obtained.
Another possibility is using transparent laser plastic welding (TLPW) in which a higher wavelength laser is used, which interacts differently with the plastic than the typical 808 nm or 980 nm infrared lasers used in through-transmission welding. Some of the laser energy is still transmitted or passed through a clear thermoplastic, but at this higher wavelength some absorption is seen, volumetrically, through the part—enough volumetric absorption to heat and plasticize the polymer.
When lasers pass through any lens (or any transmitting medium, plastics in this case) some of that laser energy will be absorbed at the surfaces of the lens. In the case of transparent plastic welding there are four surfaces where absorption will increase: the upper surface, the two surfaces at the joint interface and the lower surface. Because the interface of the joint is comprised of two surfaces the majority of the absorption in clear-to-clear welding takes place here making it a perfect solu-tion for joining clear thermoplastics without absorber additives. The advantage thereof is that there are no additives or chemicals that may contaminate the recycled resin.
In a large series of experiments applicant experienced that a laser means with a laser beam having a wavelength between 1900 and 2100 nm, preferably 2000 nm, can be used to laser weld pieces of transparent PET without the use of absorber layers. In a large series of stability tests, i.e. drop tests from 1.8 meters at a temperature of −18° C. during 24 hours, it could be proved that the laser weld joints between the separate transparent bottom part 13 and the transparent plastic container 12 have been break-proof. The melting heat is generated in the focus of the laser beam.
Instead of the pressure control device 17 with the transparent high pressure container 18 as has been depicted in
Above the dome shaped disc 50 with the pressure control device 51 a dome shaped piston 65 with scraping fins 66 is provided for separating the dispensing fluid (not shown) from the pressurized air underneath the piston 65.
The preferably dome shaped disc 50 is laser welded to the inner wall of the plastic container 12 in the same manner as described above, i. e. applying a thin ring-shaped absorber layer to the outer wall of the transparent disc 50 and then joining the mating surfaces by laser welding to the transparent container 12. Also the plastic valve 67 is laser welded to the top of the container 12 as described above with respect to the base part 13. However, different welding methods as spin welding, ultrasonic welding or vibration welding may be used.
The transparent bottom parts 20 and 40 may also have a central tube 25 or a central tube 45 which are open-ended on both ends, in which a closing element of an elastomeric material is provided. This closing element can be designed as two stage Nicholson plug 68 as can be seen in
| Number | Date | Country | Kind |
|---|---|---|---|
| 21184077.2 | Jul 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/068646 | 7/5/2022 | WO |
