STIRRER FOR A VISCOUS LIQUID

Abstract

A container (1) for a viscous liquid, in particular a colorant for paint, may comprise a stirrer (2) having a rotatable shaft (3) and a plurality of paddles (4) connected to the shaft (3). At least one of the paddles (4) and/or the connections (5) between the paddles (4) and the shaft (4) is flexible.

Claims

1. Container (1) for a viscous liquid, in particular a colorant for paint, comprising a stirrer (2) having a rotatable shaft (3) and a plurality of paddles (4) connected to the shaft (3), characterized in that at least one of the paddles (4) and/or the connections (5) between the paddles (4) and the shaft (4) is flexible.

2. Container (1) according to claim 1, wherein at least one of the paddles (4) and/or the connections (5) between the paddles (4) and the shaft (3) are configured to elastically flex and/or twist over at least 20 degrees, preferably at least 30 degrees.

3. Container (1) according to claim 1, wherein the connection (5) between at least one of the paddles (4) and the shaft (3) has a torsional stiffness of less than 1,5 Nm/rad, preferably a torsional stiffness in a range from 0,1 to 1,0 Nm/rad.

4. Container (1) according to claim 1, wherein the power taken up by the stirrer (2) rotating at 40 rpm in a liquid having a viscosity of 40 Pa.Math.s is less than 100%, preferably less than 50%, preferably less than 40% higher than the power taken up by the stirrer (2) rotating at 40 rpm in a liquid having a viscosity of 10 Pa.Math.s.

5. Container (1) according to claim 1, wherein at least some of the paddles (4) are at an inclination in a range from 30 to 60 degrees relative to the shaft (3).

6. Container (1) according to claim 1, wherein at least some of the paddles (4) are connected to the shaft (3) by means of arms (5).

7. Container (1) according to claim 6, wherein the arms (5) connect asymmetrically to the paddles (4).

8. Container (1) according to claim 6, wherein at least one preferably some or all of the connections (5) between the shaft (3) and the paddles (4) extend at an inclination, preferably in a range from 10 to 60 degrees, more preferably in a range from 15 to 50 degrees relative to a plane perpendicular to the shaft (3).

9. Container (1) according to claim 1, wherein the stirrer (2) is made of a synthetic material, preferably a thermoplastic polymer.

10. Container (1) according to claim 1, comprising a series of paddles (4) or sets of paddles (4) arranged along the length of the shaft (3).

11. Container (1) according to claim 1, wherein the lowermost paddle (4) or paddles (4) extends to the bottom of the container (1).

12. Container (1) according to claim 1, wherein the container (1) has a circular cross-section, is oblong, has a height of less than 100 centimeters, has a diameter smaller than 45 centimeters and/or extends vertically, at least when it contains the liquid.

13. Stirrer (2) for a viscous liquid, in particular a colorant for paint, having a central shaft (3) and a plurality of paddles (4) connected to the shaft (3), characterized in that at least one of the paddles (4) and/or the connections (5) between the paddles (5) and the shaft (3) are flexible.

14. Stirrer (2) according to claim 13, wherein at least one of the paddles (4) and/or the connections (5) between the paddles (4) and the shaft (3) are configured to elastically flex and/or twist over at least 20 degrees, preferably at least 30 degrees.

15. Stirrer (2) according to claim 13, wherein the connection (5) between at least one of the paddles (4) and the shaft (3) has a torsional stiffness of less than 1,5 Nm/rad, preferably a torsional stiffness in a range from 0,1 to 1,0 Nm/rad.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The disclosed container and stirrer will be further explained with reference to the accompanying drawings in which a presently preferred embodiment of the invention is shown schematically. Details, that are not necessary for understanding the present invention, may have been omitted.

[0033] FIG. 1 is a perspective view of a container comprising a stirrer in accordance with the present invention.

[0034] FIG. 2 is a front view of the stirrer shown in FIG. 1.

[0035] FIG. 3 is a top view of the stirrer shown in FIG. 1.

DETAILED DESCRIPTION

[0036] FIG. 1 shows an example of a container 1 for storing a liquid, such as colorants for paint, but also hair dyes, shampoos, foundations, and the like. It can be used in an apparatus, comprising a plurality, e.g. twelve, sixteen or twenty of such containers, for dispensing numerous recipes and formulas and located e.g. at a retailer of e.g. decorative paints.

[0037] The container 1 is provided with or coupled to a metering pump and a valve (not shown). Further information regarding suitable dispensing apparatuses and procedures for driving the various components, are disclosed in, for instance, European patent applications EP 800 858, EP 1 492 970, EP 1 688 652, and EP 2 198 950.

[0038] As shown in the Figures, the present container 1 has a circular cross-section and comprises a stirrer 2 having a rotatable shaft 3 extending through the center of the container. A plurality of paddles 4 are connected to the shaft 3 via relative thin arms 5, which extend at an inclination, e.g. 30 degrees and in downward direction, from the shaft to near the lower rim of each of the paddles. The arms 5 provide a substantial distance between the shaft and the paddles 4 and hold the paddles an angle of e.g. 45 degrees. In this example, the shaft, arms, and paddles form an integral whole and were manufactured by injection moulding a thermoplastic polymer, i.c. polyoxymethylene (POM). The combination of shape and material yielded torsional stiffness of the paddles of 0,6 Nm/rad. The paddles allowed elastical twisting over an angle of 45 degrees.

[0039] In top view, the outermost edge of the paddles is curved, having a radius 0,5 cm smaller that the inner radius of the container. The lowermost paddle extends to the bottom of the container, leaving a clearance of 1 mm.

[0040] During stirring cycles, performed e.g. one or more times per day, for a duration of from three to twenty minutes per cycle, and at a rotational speed of the stirrer in a range from 20 to 40 rpm, depending on the liquid in the container and on environmental conditions, such as temperature, the paddles generate displacement of the liquid upwards or downwards (depending on the orientation of the paddles and the direction of rotation) and the liquid circulates (downwards or upwards, respectively) in the opposite direction between the shaft and the paddles. Initially, the paddles will flex only slightly, but when the liquid ages and the viscosity of the liquid increases, the paddles will flex more, in extreme instances eventually to an almost horizontal position. Thus, the efficiency of the stirrer is reduced with increasing viscosity and, as a result, the risk of failure of the stirrer or the mechanism driving the stirrer is reduced and/or the shear forces exerted on the colorant are reduced, extending the container life of the colorant.

[0041] As a matter of course, the invention is not restricted to the above-disclosed embodiment and can be varied in numerous ways within the scope of the claims