WO2013053383A1

WO2013053383A1 - Paste container with improved dosing device

Info

Publication number: WO2013053383A1
Application number: PCT/EP2011/067733
Authority: WO
Inventors: Johannes Georg Winter; Peter Bruno BEISEMANN; Mario Manfred POSSMANN
Original assignee: Ecolab Usa Inc.
Priority date: 2011-10-11
Filing date: 2011-10-11
Publication date: 2013-04-18

Abstract

The present invention refers to a paste container and dispenser comprising a cylinder (7) open at one end for holding the paste, a displaceable tightly fitted follower plate means (2) arranged at the open end of the cylinder, a dispenser means (1) for transporting the paste from the container, a motor and transmission means having a shaft means (3) projecting centrally through the follower plate (2); a rotatable multiple-blade stirring means (4) mounted on the shaft arranged to rotate in the paste below the follower plate (2); wherein the dispenser is connected to the follower plate outside the center thereof and has means for communicating with the paste above an area covered by a blade of the stirring means (4) for transporting the paste from the container to a point of use; wherein the follower plate is provided with heating means (2a). The invention also provides a paste container and dispenser comprising a vessel for holding the paste, a dispenser means for transporting the paste from the vessel; wherein the vessel comprises an outlet and wherein the dispenser has means for communicating with the paste for transporting the paste from the vessel via said outlet to a point of use; characterized in that heating means are provided for heating that part of the paste which is in proximity to the outlet. Further a method is provided for dispensing a paste from a paste container and dispenser, wherein heat is applied to the paste to be dispensed.

Description

Paste container with improved dosing device

FIELD OF THE INVENTION The present invention refers to a paste container with improved dispensing. This invention relates to a paste container and dispenser which is particularly suitable for dispensing pseudoplastic pastes, more particularly highly viscous detergent pastes of the type used in institutional laundries. BACKGROUND OF THE INVENTION

Paste-form detergents are used in particular in institutional laundries where they have the advantages of powder-form detergents, more particularly a high active- substance content, and none of the disadvantages of liquid detergents, more particularly the water or solvent content. Disadvantages of paste-form detergents can lie in packaging and dispensing problems.

RELATED ART German patent application DE-A-37 19 906 describes a detergent container and dispenser. The storage container for the paste-form detergent is a container with rigid outer walls and a circular or square cross-section which is equipped on one side with a displaceable, tightly closing plate (follower plate). Under the effect of its weight, the follower plate applies pressure to the surface of the paste and enables the detergent paste to be withdrawn via the dispenser which may be formed by a simple pipe and pump. As the amount of paste decreases, the follower plate slowly follows the paste level downwards. The container and dispenser described in DE-A-37 19 906 may also be equipped with a mixing unit which mixes water simultaneously introduced into the dispenser with the detergent paste and thus forms a water-containing liquid concentrate which can be delivered to the individual washing machines.

German patent application DE-A-38 26 110 also describes a detergent container and dispenser for paste-form detergents. In this case, the detergent container is cylindrical with an opening at both ends. One opening is closed by a plate which is arranged in the container and designed for displacement axially thereof. The container opening situated opposite this displaceable plate carries a releasab!e connecting element with which it can be fixed or coupled to the dispenser. The connected dispenser comprises a plunger which acts on the displaceable plate of the paste container and causes it to advance as the paste is removed.

US 5,785,210 describes a dispenser container for a paste which comprises a cylinder open at one end for holding the paste, a displaceable tightly fitted follower plate means arranged at the open end of the cylinder, and a dispenser for transporting the paste from the container is arranged to cooperate with the follower plate. A motor and transmission are mounted near the center of the follower plate; a shaft which extends through the follower plate and has mounted thereon a rotatable multiple-blade stirrer. The stirrer rotates in the paste below the follower plate. The dispenser removes the paste from the container at a position in some distance from the center of the follower plate. The multiple-blade stirrer by rotating in the paste decreases the viscosity and permits the paste to be more easily transported from the container by the dispenser. A drawback of these dispensing systems described above is that the paste can not be dispensed, if due to low temperatures the viscosity of the paste is too high. The container is subjected to low temperatures for example in winter time. As the pastes are good thermal insulators it takes a long time until the temperature of a major part of the volume of the paste increases when the container is brought from an outdoor storage place into the building. The dispensing system according to US 5,785,210 works well under conditions wherein the paste contained therein has viscosities in the range from about 100 Pas to 700 Pa.s, measured with a Bohlin CVO rheometer with plate-plate geometry (2mm gap, 20mm plate diameter) at a shear rate of 0.2s^"1 and 25°C. In case the temperature of the pastes is lower the viscosities are higher, for example higher than 700 Pas or higher than 1 ,000 Pas or even higher than 2,000 Pa.s. Under such conditions it becomes difficult or even totally impossible to pump these pastes with

conventional dispensing systems. On the other hand, too low viscosity of the paste (<50 Pas under conditions described above), for example, after storage at hot temperatures, could result in a significant decrease of the dispensed amounts and it would be likely that material would be pressed up between the sealing ring of the follower plate and the drum. BRIEF DESCRIPTION OF THE INVENTION

Accordingly, the problem addressed by the present invention was to provide a paste container and dispenser which would even enable pastes with higher viscosities to be continuously removed by a dispensing and transporting system and, at the same time, would achieve a high degree of residual emptying of the paste container.

The object is solved by a paste container and dispenser comprising a cylinder 7 open at one end for holding the paste, a displaceable tightly fitted follower plate means 2 arranged at the open end of the cylinder, a dispenser means 1 for transporting the paste from the container, a motor and transmission means having a shaft means 3 projecting centrally through the follower plate 2; a rotatable multiple-blade stirring means 4 mounted on the shaft arranged to rotate in the paste below the follower plate 2; wherein the dispenser is connected to the follower plate outside the center thereof and has means for communicating with the paste above an area covered by a blade of the stirring means 4 for transporting the paste from the container to a point of use; wherein the follower plate is provided with heating means 2a. By heating selectively the follower plate of the paste container, instead of the whole paste container, the dosing reliability of paste dosing strongly improves. The present inventors found that for heating of the follower plate the use of any source of heat provides the desired effect. For example, hot air blowers for blowing hot air at the follower plate turned out to be very effective. The heated follower plate in turn heats the paste that is in immediate contact with the follower plate. This heating decreases the viscosity of the paste due to the increased temperature and therefore allows or at least eases and simplifies paste dispensing. In this way, the temperature of the "next to be dosed" paste is fixed to and/or depends on the temperature of the follower plate. By tuning the temperature of the follower plate the viscosity of the paste can be tuned as paste viscosity depends on the temperature of the paste. By this method, too cold and therefore too viscous paste can be dosed without heating the whole paste container. In fact, the temperature of all paste which is more distant to the follower plate (e.g. more than 4 or 5 cm) does not increase as the pastes are good thermal insulators. As the whole paste drum is not heated over prolonged time in order to make the paste contained therein ready to be dosed, a further effect is provided: the phenomenon of physical phase separation of pastes that occasionally occur at elevated temperatures is avoided.

In a particularly preferred embodiment of the paste container and dispenser the follower plate is provided with heating means. The heating means are suitable to heat the follower plate and by that the part of the paste which is immediately located below the follower plate or to heat directly that paste. in a preferred embodiment the follower plate is provided with temperature control means. The operation of such temperature control means allows to exactly control the temperature of the paste and by that the viscosity of the paste which depends on its chemical composition and the temperature to which it is subjected.

In a further preferred embodiment the heating means are selected from the group consisting of hot air blower, hot steam dispenser, hot water circuit, electrically driven heating circuit, infrared radiation device such as infrared light means, lasers or light bulbs; and micro wave devices, induction heating means.

In one embodiment the heating means is represented by hot air blower for applying hot air to the outer surface of the follower plate.

In a further embodiment the heating means is represented by a blower for applying hot steam to the outer surface of the follower plate.

In another embodiment the heating means is represented by hot water circuit arranged integrally in the follower plate or arranged on the surface of the follower plate facing the paste. The medium circulating in such a circuit may be any medium - including water but which is not restricted to water - which is suitable to circulate in such a device and transport and deliver heat.

In still a further embodiment the heating means is represented by infrared radiation device such as infrared light means, lasers or light bulbs for applying infrared radiation to the outer surface of the follower plate.

In yet another embodiment the heating means is represented by micro wave device for applying heat to the paste which is located immediately below the follower plate.

In an alternative embodiment the heating means is represented by induction heating means for heating the follower plate or parts thereof. Induction heating is the process of heating an electrically conducting object, usually a metal object, by electromagnetic induction, where eddy (Foucault) currents are generated within the metal and resistance leads to Joule heating of the metal. An induction heater consists of an electromagnet, through which a high-frequency alternating current is passed. The present invention also provides a paste container and dispenser comprising a vessel for holding the paste, a dispenser means for transporting the paste from the vessel; wherein the vessel comprises an outlet and wherein the dispenser has means for communicating with the paste for transporting the paste from the vessel via said outlet to a point of use; characterized in that heating means are provided for heating that part of the paste which is in proximity to the outlet.

In a preferred embodiment of the second aspect of the present invention said heating means are selected from the group consisting of hot air blower, hot steam dispenser, hot water circuit, electrically driven heating circuit, infrared radiation device such as infrared light means, lasers or light bulbs; and micro wave devices, induction heating means. These heating means are arranged in that way that heating the part or area of the paste which is in proximity to the outlet. The present invention further provides a method for dispensing a paste from a paste container and dispenser as described above, wherein heat is applied to the paste to be dispensed. in a preferred method the temperature of the paste which is dispensed is from 20°C to 50°C, preferably from 25°C to 50°C, more preferred from 30°C to 50°C, still further preferred from 35°C to 50°C, even further preferred from 37°C to 50° and most preferred from 40°C to 45°C. In a further preferred method the temperature of the paste which is dispensed is 20°C or higher, preferably 22°C or higher, further preferred 25°C or higher, more preferred 30°C or higher, still further preferred 35°C or higher, even further preferred 40°C. In yet another preferred method the temperature of the paste to be dispensed is elevated by at least 5°C or higher compared to the temperature of the remaining part of the paste, preferably 10°C or higher, further preferred 15°C or higher, more preferred 20°C or higher, still further preferred 25°C or higher, even further preferred 30°C or higher and most preferred 40°C or higher. In yet another preferred method the temperature of the paste which is dispensed is at least 5°C or higher compared to the temperature of the remaining part of the paste, preferably 10°C or higher, further preferred 15°C or higher, more preferred 20°C or higher, still further preferred 25°C or higher, even further preferred 30°C or higher and most preferred 40°C or higher. The person skilled in the art understands that the term "remaining part of the paste" means the part of the paste which is not in immediate proximity to the outlet or to the follower plate or to the wall of the container or vessel. In particular, the paste which temperature shall serve for comparison shall be defined as the paste which is located in the center of the vessel or container.

In a further preferred embodiment the paste has a viscosity, measured with a

Bohlin CVO rheometer with plate-plate geometry (2mm gap, 20mm plate diameter) at a shear rate of 0.2s^"1 and 25°C, above 600 Pas. Heating the paste to temperatures higher than 25°C decreases the viscosity and improves dispensing the paste. In a particularly preferred embodiment the paste has a viscosity, measured with a Bohlin CVO rheometer with plate-plate geometry (2mm gap, 20mm plate diameter) at a shear rate of 0.2s^"1, in the range from 100 Pas to 700 Pas and more particularly, in the range from 200 Pas to 700 pas. in a still further preferred embodiment the paste comprises a detergent, further preferred a pseudoplastic detergent.

BRIEF DESCRIPTION OF THE FIGURE

Figure 1 is a diagrammatic representation in cross-section of a dispenser of the invention.

Figure 2 is a graph showing the quantity of dispensed paste depending on its temperature.

Figure 3 is a graph showing the dependency of the viscosity of a paste product vs. temperature. DETAILED DESCRIPTION OF THE INVENTION

The paste container and dispenser according to the invention is particularly suitable for pseudoplastic pastes of high viscosity. Pseudoplastic pastes have the property whereby they become liquid on exposure to mechanical forces, for example during stirring, shaking or ultrasonication, but solidify again after removal of the mechanical force. This means that the viscosity of these pastes decreases under the effect of increasing shear stress or shear rate. Particularly suitable pastes are those of which the viscosity, as measured for example with a Bohlin CVO rheometer with plate-plate geometry (2mm gap, 20mm plate diameter), is above 100 Pas and, more particularly, in the range from 200 Pas to 700 Pas. Corresponding pastes are, for example, the paste-form detergents obtainable in accordance with the German patent application P 43 32 843.0 or the European patent application EP 1 749 081. Accordingly, a paste container according to the invention is preferably used for transporting and dispensing corresponding pseudoplastic detergent pastes.

According to one aspect of the invention, the cylindrical paste container is closed at its open end by a displaceable, tightly closing plate which is designed for displacement in axial direction of the container. The displaceable plate is intended to seal off the container wall according to the particular paste level to such an extent that the paste is unable to escape in this zone, i.e. the plate best rubs gently against the container wall during its displacement. The plate is normally flat. At the same time, the sealing effect is improved by designing the plate so that it fits exactly in the container. To prevent the displaceable plate from tilting, its edge is best bent upwards in the shape of a collar, i.e. the plate is in the form of a flat piston. The plate is preferably provided with a plastic seal at its edges. According to the first aspect of the invention the plate comprises heating means as described above in order to heat the paste which is in immediate proximity to the plate and by that to the outlet in order to decrease the viscosity.

According to the first aspect of the invention a motor and transmission system is arranged in the middle of the plate on the outside of the container on whose shaft, which best coincides with axis of the cylindrical container, a multiple-blade stirring propeller is arranged beneath the plate towards the middle of the container. This stirring propeller is arranged in such a way that it is able to rotate freely just below the follower plate. The distance of the stirring propeller from the follower plate is preferably as small as possible because the underneath of the plate can be simultaneously freed from paste, i.e. cleaned, by the propeller blades, which results in a reduction of unwanted residues on the plate. The distance of the stirring propeller from the plate is preferably 0.8 to 5 mm and more preferably 1 mm to 3 mm.

The stirring propeller has at least two blades. The blades of the stirring propeller may be equal or different in length. The stirring propeller preferably has four blades, the opposite blades preferably being equal in length. One preferred embodiment uses a four-blade stirring propeller which has two opposite blades of which the length is such that they cover the entire diameter of the cylindrical container. By contrast, the other two blades are only so long that the ends extend up to the dispenser likewise disposed on the plate. An embodiment such as this is of particular advantage where pseudoplastic pastes are used because it enables the two long blades to shear and hence liquefy the highly viscous paste while the two short blades are able to transport the paste towards the pump.

The blades of the stirring propeller normally assume the form of a flat rectangular slat or round bar. They are normally arranged parallel to the plate. In one possible embodiment, the blades are arranged at an angle of 90° to 60° to the propeller axis. This angle is preferably 89° to 65°. There is no need for all the blades to be arranged at the same angle to the displaceable plate. Where they are formed by slat-like elements, the propeller blades may even be slightly pitched. The angle of pitch is preferably between 5° and 45°.

In one preferred embodiment, the boss of the stirring propeller is shaped in such a way that it terminates the shaft of the stirring propeller at its lower end in the form of a projection. An arrangement such as this has the advantage that this projection can be used as a central spacer relative to the bottom of the container so that no excessive friction occurs when the propeller is at the bottom of the container.

The motor and transmission system used serves to drive the stirring propeller. The power of the motor is determined by the required speed of the stirring propeller and by the viscosity of the pseudoplastic paste used. The rotational speed of the stirring propeller is normally in the range from 5 to 180 r.p.m., preferably in the range from 15 to 180 r.p.m. and more preferably in range from 45 to 90 r.p.m. An excessive rotational speed is a disadvantage because the paste would then become excessively liquid and could escape at the edges of the plate. If the rotational speed is too low, the paste would not be sufficiently liquefied and continuous removal would be impaired.

As the paste is removed from the container, the plate sinks slowly according to the paste level. When the boss of the stirring propeller reaches the bottom of the container, the stirring propeller can continue to rotate for a while because, through the movement of the blades, the paste flows more easily from the edges of the container towards the middle and can be removed. The container can readily be emptied to residues of less than 1 % by the dispenser according to the invention.

The dispenser is connected to the follower plate outside the middle thereof. The dispenser is preferably formed by an eccentric screw pump, gear pump, flow inducer or injector. Through the dispenser, the paste can be directly put to its use in basically known manner by way of corresponding consumption-controlled distributors.

The container together with the plate and the dispenser are best made of a corrosion-resistant material, such as plastic, metal or glass. In the interests of a sufficiently accurate fit, the container should remain substantially dimensionaily stable in use. Although the size of the container is not critical, the contents should best last for several hours to minimize packaging and servicing costs. Corresponding paste containers normally have a volume of at least 0.2 liter. Where they are used as paste containers for institutional detergents, the containers normally have a capacity of the order of 200 liters.

An embodiment of the paste container and dispenser according to the invention is illustrated in the accompanying drawing.

The highly viscous paste 6 is accommodated in a cylindrical container 7 open at its upper end. The open end of the cylinder 7 is closed by the round plate 2 arranged in the container 7. The plate 2 is bent outwards in the shape of a collar and sealed by a plastic seal 5. The plate 2 lies on the paste and follows the paste downwards as it is removed. Disposed in the middle of the follower plate 2 is a motor 3a and transmission system 3 on the shaft of which a multiple-blade stirring propeller 4 is arranged. The shaft terminates in a boss 8 which projects slightly downwards. In the embodiment illustrated, all the blades are of equal length and extend over the entire diameter of the cylinder. These long blades also strip the paste from the cylinder wall, i.e. residues of paste on the container wall are minimized. The stirring propeller 4 is able to rotate freely under the follower plate 2. If pastes of such high viscosity are used that the dispenser is unable to transport them the follower plate and by that the paste in direct proximity to the follower plate is heated by activating the heating means 2a. In the embodiment shown in Figure 1 , the heating means 2a are represented by a electrically driven heating circuit. Any other device for heating the follower plate or directly the paste which is located immediately below the follower plate is suitable. For example, the heating means may be a hot air blower arranged above the follower plate and is arranged in that way that is blows hot air onto the outer surface of the follower plate. Another example for heating means may be represented by a by hot water circuit arranged integrally in the follower plate or arranged on the surface of the follower plate facing the paste. The medium circulating in such a circuit may be any medium (including water, but not restricted to water) which is suitable to circulate in such a device. An alternative heating means may be represented by infrared radiation device such as infrared light means, lasers or light bulbs arranged above the follower plate which direct the infrared radiation onto the outer surface of the follower plate. A further example of the heating means may be represented by a micro wave device for applying heat to the paste which is located immediately below the follower plate. A still further example for heating means is represented by induction heating means for heating the follower plate or parts thereof.

By heating the paste the viscosity of the paste is reduced to such an extent that it becomes dispensable. A dispenser 1 in the form of an eccentric screw pump is arranged outside the middle of the plate 2. The sheared and viscosity-reduced paste is put to its use, for example in an institutional washing machine, by this pump, optionally via corresponding distributing and/or metering elements.

Examples

Example 1 : Testing the influence of the temperature of the paste on the flow.

In order to find an improvement of paste dosing the flow of pastes was tested through a pipe. It was observed that the pastes flow in plough flow through the pipe, if heat was applied to the pipe walls although the inner temperature of the paste within the pipe remained lower.

Example 2: Measuring the quantity of dispensed paste depending on its temperature

In order to measure the quantity of dispensed paste the flow of pastes was tested. The following plate of a paste container and dispenser (Compactomix® dosing unit) was heated with an air heater. Upon dosing the start temperature of the pumped (dispensed) paste was measured at the outlet and the amount of paste per time was measured (a period of 30s dosing). In Figure 2 the results were summarized. It was shown that the quantity of paste which was dispensed increased with temperature, implying that the viscosity of the temperature was increased by the raise of the temperature.

Example 3: Measuring viscosity of paste depending on the temperature

In order to show the dependency of the viscosity in respect to the temperature the paste (Compactat® Future Plus, Ecolab Inc.) was given in a container a the viscosity was measured with a Bohlin CVO rheometer with plate-plate geometry (2mm gap, 20mm plate diameter) at a shear rate of 0.2s^"1 at different temperatures from 17°C to 75°C. In Figure 3 the results were summarized. It was shown that the viscosity of paste decreased with increasing temperature.

List of Reference Numerals

1 Dispenser

2 Follower plate provided with heating means (2a)

3 Transmission

3a Motor

4 Stirring blades

5 Seal

6 Paste

7 Paste container

8 Boss

Claims

1. A paste container and dispenser comprising a cylinder (7) open at one end for holding the paste, a displaceable tightly fitted follower plate means (2) arranged at the open end of the cylinder, a dispenser means (1 ) for transporting the paste from the container, a motor and transmission means having a shaft means (3) projecting centrally through the follower plate (2); a rotatable multiple- blade stirring means (4) mounted on the shaft arranged to rotate in the paste below the follower plate (2); wherein the dispenser is connected to the follower plate outside the center thereof and has means for communicating with the paste above an area covered by a blade of the stirring means (4) for transporting the paste from the container to a point of use; characterized in that the follower plate is provided with heating means (2a).

2. The paste container and dispenser according to claim 1 , wherein the follower plate is provided with temperature control means.

3. The paste container and dispenser according to claim 1 or 2, wherein the heating means are selected from the group consisting of hot air blower, hot steam dispenser, hot water circuit, electrically driven heating circuit, infrared radiation device such as infrared light means, lasers or light bulbs; and micro wave devices, induction heating means.

4. The paste container and dispenser according to any one of claims 1 to 3, wherein the heating means is represented by hot air blower for applying hot air to the outer surface of the follower plate.

5. The paste container and dispenser according to any one of claims 1 to 3, wherein the heating means is represented by a blower for applying hot steam to the outer surface of the follower plate.

6. The paste container and dispenser according to any one of claims 1 to 3, wherein the heating means is represented by hot water circuit arranged integrally in the follower plate or arranged on the surface of the follower plate facing the paste.

7. The paste container and dispenser according to any one of claims 1 to 3, wherein the heating means is represented by infrared radiation device such as infrared light means, lasers or light bulbs for applying infrared radiation to the outer surface of the follower plate.

8. The paste container and dispenser according to any one of claims 1 to 3, wherein the heating means is represented by micro wave device for applying heat to the paste which is located immediately below the follower plate.

9. The paste container and dispenser according to any one of claims 1 to 3, wherein the heating means is represented by induction heating means for heating the follower plate.

10. A paste container and dispenser comprising a vessel for holding the paste, a dispenser means for transporting the paste from the vessel; wherein the vessel comprises an outlet and wherein the dispenser has means for communicating with the paste for transporting the paste from the vessel via said outlet to a point of use; characterized in that heating means are provided for heating that part of the paste which is in proximity to the outlet.

11. A method for dispensing a paste from a paste container and dispenser according any one of claims 1 to 10, wherein heat is applied to the paste to be dispensed.

12. The method according to claim 11 , wherein the temperature of the paste to be dispensed is elevated to 20°C or higher, preferably 22°C or higher.

13. The method according to claim 1 , wherein the temperature of the paste to be dispensed is elevated by at least 5°C or higher compared to the remaining part of the paste.

14. The method according to any one of claims 11 to 13, wherein the paste has a viscosity, measured with a Bohlin CVO rheometer with plate-plate geometry (2mm gap, 20mm plate diameter), in the range from 100 Pas to 700 Pas and more particularly, in the range from 200 Pas to 700 pas.

15. The method according to any one of claims 11 to 14, wherein the paste comprises a pseudoplastic detergent