EP0711367B1

EP0711367B1 - Process for dosing detergent compositions

Info

Publication number: EP0711367B1
Application number: EP94919675A
Authority: EP
Inventors: Leendert Los; Marcellus Gerardus Dusamos; Johannes Jacobus Blom
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1993-07-30
Filing date: 1994-06-30
Publication date: 1998-03-25
Anticipated expiration: 2014-06-30
Also published as: FI960386A; BR9407105A; DE69409240D1; EP0711367A1; AU7073894A; AU694435B2; FI960386A0; ES2114205T3; ZA945004B; DE69409240T2; WO1995004183A1

Abstract

A process is provided for dosing a detergent composition which is in the form of a liquid, paste or a gel, of which the viscosity increases when brought into contact with water, into a washing machine, whereby the detergent composition is transported from a container for holding the composition (10) to the washing machine (13) via a conduit and a valve, characterised in that (i) said valve is a dosing valve (12) including a product inlet (1), a product chamber (2), a product outlet (3) and a plunger (4), said plunger being electromagnetically or pneumatically actuated; and (ii) said valve is opened and closed by quick movement of the plunger in a direction along its axis away from respectively into the product outlet. When applying this process, the risk of such contact between detergent material and water that blockage could occur, was found to be effectively prevented. Furthermore, this process was found to be simple, safe and reliable, resulting in reduced installation cost with regard to the dosing system required.

Description

FIELD OF THE INVENTION

The present invention relates to a process and a device for dosing detergent compositions into a washing machine. More in particular, it relates to a process and a device for dosing detergent compositions which are in the form of liquids, pastes or gels,of which the viscosity increases when they are brought into contact with small amounts of water.

BACKGROUND OF THE INVENTION

Detergent compositions in the form of pastes are known in the art, for instance from the US patent 3,850,831. Moreover, there exist non-aqueous liquid detergent compositions which undergo a drastic viscosity increase upon contact with water, or even form gels. Crystallization of solid components may also occur under such conditions. Examples of such non-aqueous liquid detergent compositions are given in the European patent application 266,199 (Unilever).

Although the above-mentioned pastes or gel-forming liquid detergent compositions may be perfectly satisfactory from a performance point of view, they have not been used extensively so far. Especially in industrial washing machines, such as fabric washing machines or ware washing machines, it was found to be a problem to deliver non-aqueous liquid detergent compositions in a simple, safe and reliable manner into the machine. In such machines, liquid detergent products are conventionally dosed by pumping them from a container via a conduit to the inside of the machine. The water present inside the machine was found to lead to unwanted viscosity increases, phase separation and gel forming of the non-aqueous liquid, whereby the product conduit may clog completely.

The European patent application 295,525 (Henkel) discloses a process for dosing paste-like detergent compositions into a washing machine, which process is developed to overcome the above-mentioned problems. However, the system used for this process was found to be very complicated and rather expensive.

Another, more simple, process for dosing liquids which tend to form gels upon contact with water, into a washing machine, is disclosed in European patent application 480,490 (Unilever). In this process, the problem of unwanted viscosity increase, phase separation and gel formation upon contact with water, is overcome by applying pressurised gas, preferably steam, for purging the conduits used for transporting the detergent liquid composition into the washing machine, after each dose of said liquid composition. This so called "steam-flush" dosing process which is preferably applied in a device including a three-way valve, has proven to be very reliable when used in conjunction with an industrial washing machine.
However, it is rather expensive because steam, air, and electrical power are needed to operate it and, as a consequence, several installation engineers with different skills are needed to install the system required for carrying out said process, resulting in relatively high installation costs.

It is, therefore, an object of the present invention to provide a process for dosing a detergent composition which is in the form of a liquid, paste or gel, of which the viscosity increases when it is brought into contact with small amounts of water, into a washing machine, which process overcomes one or more of the above drawbacks.

DEFINITION OF THE INVENTION

Accordingly, the present invention provides a process according to claim 1.

DETAILED DESCRIPTION OF THE INVENTION

The process of the present invention appears to be surprisingly simple and reliable, resulting in reduced installation cost with regard to the dosing system required. The dosing valve applied therein was found to effectively prevent the risk of such contact between detergent composition and small amounts of water that blocking could occur. Reason is that the closing action of the valve is performed in such a short time period and with such force that water is prevented from entering the valve and that the product outlet of the valve is cleaned during the closing action. Furthermore, no clogging of detergent material can take place inside the dosing valve, because there are no "dead" holes or zones in the product outlet area of the valve.

The process of the invention may be used for dosing detergent material into both domestic and industrial washing machines. In the latter case, the plunger in the dosing valve applied therein is, preferably, pneumatically actuated. For that purpose, the plunger is desirably connected to a piston which is movable inside a hollow air-filled cylinder, whereby the internal volume of said cylinder is divided by the piston into two partial volumes, and whereby each of these partial volumes is connected to means for supplying compressed air thereto and to means for deaerating them. Consequently, the dosing valve is opened and clpsed by supplying compressed air to the first respectively the second of said two partial volumes and by simultaneously deaerating the other partial volume.

The air-filled cylinder containing the movable piston, preferably, comprises a spring which is connected to the piston. This spring was found to be useful as it accelerates the closing action of the dosing valve. The spring also makes the dosing valve fail-safe: it closes the valve automatically at a power failure or a malfunctioning compressed air supply system, thus ensuring a safe and reliable operation of the dosing valve.

The air-filled cylinder enables the piston to move along the axis direction of the plunger to which it is connected, when the dosing valve is opened or closed by the action of the compressed air on to the piston.

The detergent composition flowing out of the dosing valve may be transported directly into the washing machine. The detergent composition is preferably injected into the washing machine at a level below the water level inside said machine in order to diminish the risk of undesirable viscosity increases due to humidity uptake by the detergent composition at the product outlet area of the dosing valve. This risk is diminished because at a level below the water level any product residue formed at the outside of the outlet of the valve is rinsed off by the wash liquor present in the washing machine. Another advantage of injecting the detergent composition below the water level is that, as a result, a more homogeneous distribution thereof in the wash liquor will occur; when a fabric washing machine is used this will result in reduced risk of textile damage.

When the detergent composition is transported into a single- wall industrial tunnel washer, it is generally dosed through the axis thereof into specific sections of said tunnel washer. In order to avoid any risk of solidification of the detergent material inside this type of tunnel washer, it is desirable to install a dosing valve suitable for use in the process of the invention on a mixing tank and have the detergent material flowing out of said dosing valve diluted with water in said mixing tank before it is transported into the tunnel washer. EP-A-295,525 also relates to a dosing system in which a mixing tank is applied. However, the dosing system disclosed by this document is much more complicated than the above-described system.
Adequate dilution is obtained in the mixing tank at a weight ratio of detergent composition to water being in the range of from about 1:5 to about 1:20. In order to ensure that a constant weight ratio of detergent composition to water is maintained in the mixing tank, the water flow into said tank is desirably controlled.

The mixing tank used for dilution of the detergent composition may have any shape or size. It has effectively an internal volume of 50-150 litres, and is desirably equipped with a level detection device for controlling the level of the diluted detergent product present therein.
Furthermore, the mixing tank has effectively a sloped shape at its bottom side, and is preferably equipped with a circulation system including a circulation pump, preferably a centrifugal pump, in order to obtain a homogeneously diluted detergent product. The content of the mixing tank is effectively circulated at a rate of from 4-10 times its internal volume per minute. The outlet of the mixing tank is usually connected with one or more pumps for transporting the diluted detergent product to one or more washing machines.

Not only for single-wall but also for double-drum industrial tunnel washing machines, the above-described dosing system including a mixing tank can be suitably applied for carrying out the process of the invention. However, a more simple system not involving a mixing tank, was also found to be very safe and reliable when carying out the process of the invention for dosing detergent material into a double-drum industrial tunnel washing machine. Furthermore, it was found that the dosing process of the invention can be effectively applied for dosing detergent material to all double-drum sections and the funnel of an industrial tunnel washer.

A second dosing valve according to the present invention may be effectively applied as a flow-check or sampling valve, by connecting said second valve to the conduit through which the detergent composition is pumped from a container for holding it to the first dosing valve. Like most dosing systems, the dosing system used for the process of the present invention should be controlled regularly on its pump delivery per unit of time. Sometimes, there is also the need to tap some product for other purposes. Normally, a hand-operated 3-way valve is used as a flow-check or sampling valve. However, due to the nature of the detergent composition applied, a second dosing valve according to the invention is preferably used as flow check and sampling valve in the dosing system suitable for applying the process of the invention.
The main reasons why the dosing valve used in the process of the present invention is also very suitable for use as a sampling or flow-check valve are the following:

(i) It prevents contamination of the detergent product with humid air;

(ii) It does not contain "dead" corners in the product outlet region of the valve, where solidification may occur and which may give rise to dripping;

(iii) Its operation is very user-friendly.

When the process of the invention is used for transporting detergent product to an industrial washing machine, this may effectively be carried out by applying a central chemical feed line which is connected to the washing machine and which can be flushed after each dose of detergent product. If needed, also other chemical products, such as bleaching agents, neutralizing acids and softeners, may be injected into the washing machine via this central chemical feed line.

Examples of detergent products which can be suitably dosed by applying the process of the present invention, are the non-aqueous liquids disclosed in the European patent application 543,443 (Unilever).

The invention will now be further explained by means of the accompanying Figures, in which:

(a) Figure 1 shows schematic views of the dosing valve used in the process of the present invention, in the closed (A) and in the open (B) position.

(b) Figure 2 gives a schematic view of a system suitable for the process of the invention, showing a dosing valve for injecting detergent product into a washing machine and a flow check/sampling valve.

(c) Figure 3 gives a schematic view of a system suitable for the process of the invention, showing a mixing tank for diluting the detergent material to be dosed into a washing machine.

The dosing valve shown in Figure 1, comprises a product section including a product inlet (1), a product chamber (2), and a product outlet (3). This product section also contains part of a plunger (4) which is connected to a piston (5). This piston is movable in a direction along the axis of the plunger inside an air containing cylinder (6), by applying air on one or the other side of the piston.

Figure 1 (A) depicts the closed position of the dosing valve, which position is obtained by injecting compressed air into the air containing cylinder by way of nozzle (7b). This compressed air pushes the piston and plunger into a valve seat near the outlet of the dosing valve. Simultaneously, the part of the internal volume of the cylinder (6) which is situated on the other side of the piston, is quickly deaerated via nozzle (7a).
This closing action of the nozzle is accelerated by the action of spring (8) which is attached to the piston and positioned inside the cylinder. This spring (8) has a second important function: at power failure or malfunctioning of the compressed air supply-system the valve closes automatically by means of this spring, thus ensuring a fail-safe and reliable operation.

The dosing valve is opened again by injecting compressed air into the air cylinder via nozzle (7a), thus causing the plunger (4) to move out of the outlet valve seat. Simultaneously, the air volume (6b) at the other side of the piston is quickly deaerated via nozzle (7b). In the opened position of the valve, as shown in Figure 1(B), product can be dosed.

Spring (9) is present for positioning the sealings between the product part and the air cylinder part of the dosing valve. The hole in the valve housing and situated close to this spring can be used to inspect these sealings and to drain product in case of a leakage.

It is emphasized that the dosing valve shown in Figure 1 illustrates a preferred embodiment of a dosing valve suitable for use in the process of the invention, and that various constructional alternatives will be immediately evident to the man skilled in the art, without departing from the scope of the present invention.
Particularly, electromagnetically actuated dosing valves which are especially suitable for domestic applications, are considered to be within the scope of the present invention.

Figure 2 shows a container (10) in which a non-aqueous liquid detergent product (NAL) is stored. The product is transported by the action of a pump (11) via a dosing valve (12) according to the present invention into a washing machine (13). Pressure switch (lla) is included as a safeguarding measure: with this switch, the product line from pump (11) to dosing valve (12) is monitored and protected against overpressure.
Furthermore, a second valve (14) is shown in this Figure 2, which valve is equal to the dosing valve (12) in respect of its configuration and operation. Both valves are connected to a source of compressed air (15) having a working pressure of 6 Bar, via air switch elements (16). These switch elements monitor the pressure of the compressed air (15) and safeguard the operation of valves (12) and (14) thereby prohibiting their use at a compressed air pressure below 3 barg.

Figure 3 shows a mixing tank (17) into which non-aqueous liquid detergent product (NAL) is dosed by the dosing valve (12). The mixing tank is also filled with water for diluting the NAL product, via water flow indicator (20). The water flow into the mixing tank is controlled in order to obtain a constant weight ratio of NAL to water.
It can be seen that the mixing tank is equipped with a level detecting device (19) and a circulation system including a centrifugal pump (18). This circulation system ensures that the NAL product is homogeneously diluted before being transported by pump (21) to a washing machine (13).

Claims

Process for dosing a detergent composition which is in the form of a liquid, paste or a gel, of which the viscosity increases when brought into contact with water, into an industrial washing machine, whereby the detergent composition is transported from a container for holding the composition via a conduit and a valve (10) to the washing machine (13) at a level which is below a water level inside said machine, characterised in that

(i) said valve is a dosing valve (12) including a product inlet (1), a product chamber (2), a product outlet (3) and a plunger (4), said plunger being electromagnetically or pneumatically actuated;

(ii) said valve is opened and closed by quick movement of the plunger in a direction along its axis away from respectively into the product outlet; and

(iii) the liquid detergent composition flowing out of said valve is diluted with water inside a mixing tank (17) before being transported to the washing machine, the weight ratio of detergent composition to water obtained in the mixing tank being in the range of from about 1:5 to about 1:20.
Process according to claim 1, wherein the plunger (4) is pneumatically actuated, whereby it is connected to a piston (5) which is movable inside a hollow air-filled cylinder, whereby the internal volume of said cylinder is divided by the piston into two partial volumes (6a,6b), each of which being connected to means for supplying compressed air thereto and for deaerating them (7a,7b), and whereby the dosing valve is opened and closed by supplying compressed air to the first (6a) respectively the second (6b) of said two partial volumes and simultaneously deaerating the other partial volume.
Process according to claim 2, wherein the dosing valve comprises a spring (8) which is connected to the piston (5) and situated inside the air-filled cylinder (6).
Process according to claim 2 or 3, wherein there is provided a second valve (14), of which the operation and configuration are equal to the dosing valve (12), and which is connected to the conduit for transporting the detergent composition to the dosing valve.
Process according to any of claims 1-4, wherein the mixing tank (17) is equipped with a circulation system including a circulation pump (18).
Process according to any of claims 1-5, wherein the detergent composition is dosed into the washing machine via a central chemical feed line, whereby this feed line is flushed with water after each dose.
Process according to any of claims 1-6, wherein the detergent composition is a non-aqueous liquid.