Pre-dispersion

Description

Background of the invention

[0001] Paper, board and such products are invariably made by dispersing fibres in much water and dewatering the resulting low-consistency slurry through a sieve. Originally this could have been done by dipping a rectangular sieve with removable raised edges into a vat of pulp and letting the water drain away leaving a sheet of wet paper on the sieve. This would have been laid wet paper-side down onto a piece of felt, the sieve lifted away to leave the wet paper on the felt whereby another felt would be laid on top and after pressing and drying, a sheet of paper would have been the result.

[0002] Since many years, all this has been done mainly on large, continually moving machines where the sieve is a continuous length of plastic woven sieve, known as a formation wire, revolving over guide-rolls. The pre-dispersed fibres and possibly fillers, at a consistency of perhaps 1 % in water or less, are fed onto the moving wire through a slotted gap or whereby the water drains away leaving a continuous sheet of wet paper. The slurry could contain starch and sizing substances to improve the final paper characteristics.

[0003] The water used in the various processes is normally re-cycled as far as possible, especially as large quantities of water are used. Even with modern developments in water re-cycling, it could be that 10 tons of fresh water would be consumed in making 1 ton of paper and some modern paper machines can produce 1000 tons of paper per day.

[0004] During these processes, both to prepare the fibrous pulp by chemical cooking of wood or by re-cycling waste paper, and to make the paper or board, a variety of process chemicals may be added. These substances may be solids which are insoluble in water, they may be soluble in water and already in a dissolved state, they may be in the form of emulsions including tensides. The tensides support dispersion in the water systems of the papermaking processes.

[0005] In contrast to the papermaking materials intended to be part of the final paper, such as fibres, fillers, starch, etc. many of these process chemicals are intended to influence only the papermaking process to allow the various stages to run as problem-free and efficiently as possible.

[0006] Into this category would come such process chemicals as de-foamers, deaerators, de-inking additives, biocides, adhesion inhibitors against stickies, deposit-control additives amongst others.

[0007] Such process chemicals could be added continuously or as shock-dose directly to the water circuits of the plant or could be applied to various parts of the plant such as formation wires, press-felts, drying-fabrics etc. via spray-bar systems to achieve the required treatment effects.

[0008] A significant proportion of such additives are added to control foam or remove entrained air from water circuits. Another significant proportion of such additives are used to reduce and control contamination of the surfaces in the circuits caused by bacterial slime deposits, chemical deposits such as natural resins, synthetic substances from re-cycled waste paper (commonly known as "stickies") etc. Clearly in a process where so much water is used, any process chemicals added should at least initially be able to be dispersed throughout the system to reach the various parts to be treated.

Summary of the present invention

[0009] However, many of the functional substances involved are not easily miscible in water or may be completely immiscible. For instance de-foamers can comprise natural or mineral oils or alternatively, cleaner compositions to reduce problems caused by sticky contamination can consist of organic solvents.

[0010] Further, such oils or solvents, if not correctly dispersed, collect as large globules on the water surface and adversely affect the paper being produced by creating visible oil flecks in the paper or actually disturb the process.

[0011] To overcome this, many such immiscible substances are supplied already pre-dispersed in emulsified form stabilized by emulsifying tensides. The tensides provide long-term stability of several months, whereby the emulsions show particle sizes of below 1 µm. The average mean particle size is generally around 100 nm. Such compositions are described in EP 0 828 889 B9 and EP 0 731 776.

[0012] In another composition as described in EP 517 360 A1, the additive comprises tenside and solvent whereby the most preferred additive comprises 50-90% surfactant and 10-50% solvent.

[0013] Some of the so far known cleaning or deposit control compositions comprise a significant level of emulsifier as well as water so the product can be supplied and stored as a long-term stable emulsion or if comprising only tenside and solvent, some comprise enough tenside to form an emulsion in the water-containing system.

[0014] In many cases the tenside or emulsifier component of an additive can be contra-productive in that it can lead to foaming or even that it impedes the fast release of the actual active component from the emulsified state. With anionic tensides, it can be that these will be seen as so called "anionic disturbing substances" or "anionic trash" in that some important papermaking chemicals such as flocculating agents are of a cationic charge nature and can be negatively influenced by such anionic substances.

[0015] A further disadvantage of pre-emulsified process chemicals is that they must be manufactured in the first place. That many such products are oil-in-water emulsions with say only 20% active content also means that significant amounts of water are being stored and transported. Additionally the emulsions including the tensides are not always stable particularly when being diluted in water-containing systems.

[0016] These problems are solved by the method and the pre-dispersion according to the present invention. The present invention provides a method of dispersion at least one substance in a water-containing system without the use of tensides. Further the method according to the present invention does not involve the presence of long-term stable microemulsions but involves the presence of metastable pre-dispersions having an average particle size of from 1 µm to 1 mm.

[0017] The method and the pre-dispersion according to the present invention show several advantages. Apparently cleaning can be carried out in a more environmental friendly way. Further it can be avoided that oily products float up and agglomerate into unwanted lakes and large globules when dilution occurs in places not having permanent disturbance by the technical facilities in industrial plants. Additionally the pre-dispersions according to the present invention show defoaming activity which enables the reduction or even abdication of additional defoaming agents.

[0018] In other industries such as the foodstuffs industry, it can be that although an active process chemical, such as a defoamer oil based on an edible oil, carries the necessary approval for use in the preparation of food, an emulsifying tenside may not be exactly fitting as although it may carry legal approval, it may impart an undesired taste or other undesirable characteristic. Further defoamer activity is desired in applications such as pre-cooking or blanching vegetables prior to freezing.

[0019] In the waste water industry the method according to the present invention comprising the pre-dispersion avoids an unwanted influence on the bacterial metabolism caused by tensides.

Summary of the present invention

[0020] Particularly the present invention relates to a method for dispersing at least one substance in a water-containing system including the following steps of

a) addition of at least one substance having a solubility in deionised water at 20°C of maximum 0.05 mol/l each to water;

b) dispersion of the at least one substance without the use of a tenside by supply of energy such that a metastable pre-dispersion having a mean particle size of from 1µm to 1 mm is formed and the resting pre-dispersion is stable for a minimum of 3 minutes and a maximum of 60 minutes and thereafter the pre-dispersion decomposes,

c) addition of the pre-dispersion prior to decomposition to a water-containing system.

[0021] The term "a solubility in deionised water at 20°C of maximum 0.05 mol/1 each" as used herein refers to the creation of standard solutions. Standard solutions have particle diameters of below 5 nm.

[0022] The pre-dispersion may decompose by the mean particle size exceeding 1mm and/or by creaming and/or oiling and/or sediment formation.

[0023] The present invention relates a pre-dispersion having a mean particle size of from 1µm to 1 mm, preferably 2µm to 500 µm and most preferably 5 µm to 100 µm.

[0024] The present invention further relates to pre-dispersion comprising at least one substance having a solubility in deionised water at 20 °C of maximum 0.05 mol/1 each and water, whereby the mean particle size of the pre-dispersion is from 1 µm to 1 mm, and whereby the pre-dispersion is stable for a minimum of 3 minutes and a maximum of 60 minutes, and wherein the pre-dispersion does not contain a tenside.

Mean particles size evaluation

[0025] The mean particle size is measured according to the following method.

[0026] A so-called particle counting chamber is used together with a microscope fitted with a digital camera to examine a given volume of the pre-dispersion. The apparatus comprises a precision glass base with engraved lines spaced 50 microns (µm) apart, crossing each other thus providing ruled squared areas of 50 x 50 µm. Each side of the flat area generally has two raised parts where a glass slide is placed creating a depth of 100 µm. A suitable counting chamber is for example model Reference 0640710 supplied by Paul Marienfeld GmbH&Co.KG of Lauda-Konigshofen, Germany.

[0027] A drop of the dispersion is placed on the counting-chamber. A glass cover slide is placed on the chamber to trap a 100 µm thick film of dispersion over the ruled 50 µm calibration lines. The counting-chamber is placed under an optical microscope. As an example a 40 x objective lens can be used together with digital camera. Using the same setting, photos of the ruled calibrations of the empty counting chamber are taken as calibration reference. The mean particle size is then determined on the basis of the photos taken. Computer assisted analysis is possible.

Metastability

[0028] The supply of energy according to present invention is controlled such that a metastable pre-dispersion is produced. Metastability means that the pre-dispersion is only stable for a particular time range. In the present invention the supply of energy is adjusted that the pre-dispersion has a minimum stability of 3 minutes and a maximum stability of 60 minutes. Preferably the pre-dispersion should have a minimum stability of 3 minutes and a maximum stability of 45 minutes. Most preferably the pre-dispersion should have a minimum stability of 4 minutes and a maximum stability of 30 minutes. The pre-dispersion can decompose by agglomeration of particles whereby the particle size is increased over the limit of 1mm. Additionally, or as an alternative, the pre-dispersion may decompose by creaming and/or oiling and/or sediment formation.

Emulsion stability when being diluted

[0029] Preferably the supply of energy in step b) of the method according to the present invention is selected such that the pre-dispersion has a stability of at least 5 minutes according to the World Health Organisation Emulsion Stability Test Specification WHO/M/13.R4 revised 10^th December 1999. The water used should have a hardness of 342 mg/l calcium carbonate according to WHO method WHO/M/29 version approved 25^th September 1989. Creaming and/or oiling and/or sediment formation can easily be measured by using a Turbiscan instrument supplied by the company Formulaction of L'Union, France. The Turbiscan principal is that a pulsed laser light source at 850 nm wavelength is applied to a cylindrical glass tube in which a sample of the original dispersion is held. A detector measures the directly transmitted light energy and a second synchronised detector measures the light that is back-scattered from the dispersion. The light source and detector are programmed to repeatedly scan down the glass cylinder and measure the transmitted and scattered light at intervals of 40 µm. This procedure is conducted over the time frame of the stability requirement. The mean particle size can be measured from 0.05 µm up to 1 mm with this technique. Particle migration (creaming), particle size variations (agglomeration), phase separation can all be measured. Thus each pass down the cylinder creates a curve of a function of transmitted light and back-scattered light over the height distance measured. Over the time of the test, the repeated measurement produces a series of overlayed curves which show either no change or gradual changes depending on the position of measurements down the cylinder.

[0030] The method according to the present invention involves applying energy to the mixture of the at least one substance having a solubility in deionized water at 20°C of maximum 0.05 mol/l each, whereby the energy may be added through at least of one of the following provisions:

• mechanical means including shaking, beating, stirring and/or turbulent mixing
• injection of the at least one substance into the aqueous mixture or the other way around
• creation of vibration and/or cavitation in the mixture through pressure change and/or the effect of ultrasonic devices
• combining the separated components in a static-mixer and/or micro static-mixer.

[0031] The at least one substance having the above mentioned low solubility is selected from, hydrogen-treated petroleum distillate fraction, white spirit, including high-flash dearomatized white spirit, paraffin oils, edible fats and edible oils, silicone oils, aliphatic alcohols with 8 to 26 carbon atoms, fatty acid esters and derivatives thereof, ethylene oxide and/or propylene oxide oxylated derivatives of fatty acid esters, waxes derived from mineral oils including paraffin waxes, natural waxes, etheric oils and terpenes of natural origin including orange terpene. Preferable the substance is selected from white spirits and more preferably from high-flash, dearomatized white spirit. Preferable substances also include rapeseed oil methylester (biodiesel) and mixtures of white spirit with terpenes. Particularly preferred are mixtures of high-flash, dearomatized white spirit with orange terpene. Further substances are listed in Table 2.

[0032] The total amount of the substance or the substances having low solubility according to the definition given above is generally below 33 vol% in the pre-dispersion. Preferably the amount is below 12 vol% and even more preferably the amount is below 6 vol% in the pre-dispersion. Most preferably the amount is below 3 vol%. Additionally it is a specific advantage of the method according to the present invention that the pre-dispersion may optionally be diluted by water after preparation of the pre-dispersion according to step b) and before addition of the pre-dispersion to the water-containing system keeping up the metastability properties. Upon dilution the total amount of substance / substances may be reduced to below 2 vol% and preferentially to below 1.5 vol%. This embodiment may be combined with all other options mentioned in the specification and the claims.

[0033] The water-containing system comprises water and optionally at least one substance selected from natural and/or synthetic fibres and fines thereof, natural and/or synthetic fillers and/or pigments and/or solids, natural and/or synthetic polymers and resins, inorganic salts, suspended or surface-adhering micro-organisms, substances used in paper and pulp manufacture. The water-containing system may alternatively comprise compounds as generally present in waste water facilities.

[0034] The water-containing system as used in the method according to the present invention includes may be for example a paper machine circuit, a circuit in a fibrous-pulp producing plant, a waste water circuit, or an industrial fresh water preparation plant. All vessels and pipe-work used in any of these systems shall be included.

[0035] The addition according to step c) should be carried out prior to decomposition of the pre-dispersion. Generally a time limit of a maximum of 15 minutes is appropriate. Preferably step c) is carried out up to 10 minutes after preparation of the pre-dispersion and more preferably 5 minutes after preparation of the pre-dispersion. In the pre-dispersion the time limits are the same. Therefore the additional step has to be carried out within the time limits.

[0036] The present invention further relates to a pre-dispersion comprising at least one substance having a solubility in deionised water at 20 °C of maximum 0.05 mol/l each as a first component and water as a second component, wherein the mean particle size of the pre-dispersion is in the range of from 1 µm to 1 mm, and wherein the pre-dispersion is stable for a minimum of 3 minutes and a maximum of 60 minutes, and wherein the pre-dispersion does not contain a tenside. "Not containing a tenside" means that the total amount of tenside components is below 2 wt.%, preferable below 1 wt.% and most preferable below 0.5 wt.%.

[0037] Further the pre-dispersion according to the present invention preferably has a stability of at least 5 minutes according to the World Health Organisation Emulsion Stability Test Specification WHO/M/13.R4 revised 10^th December 1999 in water having a hardness of 34.2 mg/l calcium carbonate according to WHO method WHO/M/29 version approved 25^th September 1989.

[0038] The pre-dispersion according to the present invention preferably has a mean particle size within the range of 2 µm and 500 µm and more preferably within the range of 5 µm and 500 µm.

[0039] The pre-dispersion according to the present invention comprises at least one substance having a solubility in deionised water at 20°C of maximum 0.05 mol/l each as a first component, wherein this first component is selected from hydrogen-treated petroleum distillate fraction, white spirit, including high-flash dearomatized white spirit, paraffin oils, edible fats and edible oils, silicone oils, aliphatic alcohols with 8 to 26 carbon atoms, fatty acid esters and oxylated derivatives thereof, ethylene oxide and/or propylene oxide oxylated derivatives of fatty acid esters, waxes derived from mineral oils including paraffin waxes, natural waxes, etheric oils and terpenes of natural origin including orange terpene, biodiesel. Any mixtures of the aforementioned substances are also possible. This includes double and triple mixtures as well as mixtures of more than 3 substances. Preferred mixtures include mixtures of white spirit with terpenes including high-flash dearomatized white spirit with orange terpene. Particularly preferred are mixtures of high-flash dearomatized white spirit with orange terpene in a ratio of from 50/50 to 90/10 (white spirit / orange terpene) whereby the amounts of the substances refer to wt%. Even more preferred is a ratio in the range of 70/30 to 90/10 high-flash dearomatized white spirit with orange terpene (wt% ratio). Further substances are listed in Table 2.

[0040] The pre-dispersion according to the present invention preferably has a total amount of the substance or substances having a solubility in deionised water at 20°C maximum 0.05 mol/1 each below 12 vol%. More preferably the total amount of the substance or substances having a solubility in deionised water at 20°C maximum 0.05 mol/l each below 6 vol% and most preferably below 3 vol%.

[0041] The pre-dispersion according to the present invention may be obtained by a process as described above.

[0042] The pre-dispersion according to the present invention can be used as a cleaning agent in industrial plants. Additionally the pre-dispersion according to the present invention can be used as de-foamer, de-aerator, adhesion inhibitor against stickies and/or cleaner in the paper and pulp industry, including re-cycle pulp production, the foodstuffs industry or in waste-water treatment.

[0043] The invention shall be explained in more detail in the examples presented below.

Examples

Example 1. Pre-dispersion based on white spirit / mechanical dispersion

[0044] A dispersion of a solvent in water was produced by pumping certain proportions of both the solvent and water under pressure firstly through a static mixer to premix the two immiscible liquids and then through a variable orifice into an area of lower pressure.

[0045] A variable speed progressive cavity pump (Supplied by Gebrüder Netzsch Maschinenfabrik GmbH & Co. KG, Austria) with a maximum capacity of 19 1/h was used to pump a solvent comprising of a high-flash, de-aromatized white spirit. The high-flash, de-aromatized white spirit used was a hydrogen-treated petroleum distillate fraction with an initial boiling point of 180°C. The pump could be adjusted using a built-in variable-speed gearbox to deliver from 2 1/h up to 20 1/h of liquid and depending on the back-pressure in the system up to a maximum permitted working pressure of approximately 15 bars. A similar pump was used to pump normal fresh water. The water used was industrial fresh water with a hardness measured as equivalent to 214 mg CaCO₃/l (12° German Hardness).

[0046] The outputs of both pumps were fed into the entry of a static mixer comprising a 20 cm long, 19 mm internal diameter stainless-steel pipe packed tightly with stainless-steel wool. The entry end of the static-mixer was equipped with T-piece fitted with a manometer to measure the input pressure. On the outlet of the static-mixer was fitted an adjustable stainless-steel needle-valve, the outlet of which was fitted with a 30 cm long, open-ended plastic pipe with an internal diameter of 5 mm which acted as a collector to prevent aerosols spraying into the surrounding.

[0047] With the needle-valve in a fully open position the pump for water was started and adjusted to a flow of 16 1/h. the needle valve was closed down until a back pressure of 10 bars was showing on the manometer. The flow was measured with a measuring cylinder and stop-watch and corrected to 16 1/h. the needle valve was now opened slightly to drop the back pressure. The pump for solvent was started and adjusted to an approximate flow of 8 1/h measured as a total of 24 1/h total with the water. The needle-valve was progressively closed down until the manometer showed a back-pressure of 10 bars and the solvent pump was readjusted to maintain 24 1/h total flow.

[0048] After a short time the liquid flowing from the extension pipe on the needle-valve turned milky-white. The temperature of the dispersion was 23°C. This liquid was collected into a clean 100 ml measuring cylinder for further measurements.

Example la

[0049] Example 1 was repeated whereby the output of the both pumps were adjusted such that the final pre-dispersion comprises a total amount of white spirit of 30 vol%.

Example 2 Pre-dispersion based on a mixture of white spirit and orange terpene / mechanical dispersion

[0050] The same procedure as described in example 1 was used to prepare a dispersion-in-water of a mixture of solvent except that the solvent used was a mixture of 80% wt/wt of the high-flash de-aromatized white spirit and 20% wt/wt orange terpene.

Example 3 Pre-dispersion based on rape-seed oil methyl ester

[0051] The same procedure as described in example 1 was used to prepare a dispersion-in-water of a mixture of solvent except that the solvent used was an ester of a fatty acid namely a rape-seed oil methyl ester in the form of commercial biodiesel intended as fuel for diesel-powered cars.

Example 4 Pre-dispersion based on white spirit / microemulsifier

[0052] Two pumps as described in example 1 were used to feed water and high-flash, de-aromatized white spirit directly to the two entry pipe positions of a special micro-emulsifier unit known as a "model CPMM-V 1.2 R600 caterpillar mixer" from the company IMM Institut für Mikrotechnik Mainz GmbH, Germany. This device was technically a static-mixer and had a specially shaped channel of approximately 1 mm diameter and 3 cm long etched into the surfaces of two metal plates which were clamped together.

[0053] A manometer was fitted to the pipe feeding the water to the entry side of the mixer. The outlet of the mixer was fed via a plastic pipe into a collecting vessel. The liquid mixture was forced through the caterpillar mixer causing highly turbulent mixing of the components. The pressure drop over the mixer with a total flow of 24 1/h was 15 bars given by an inlet pressure of 15 bars on the manometer and that the outlet flowed directly into a vessel at atmospheric pressure.

[0054] The liquid flowing out of the outlet of the caterpillar mixer was milky-white and was fed directly into a receiving vessel.

Example 5. Mean particle size determination

[0055] A so-called particle counting chamber was used together with a microscope fitted with a digital camera to examine a given volume of mechanically dispersed solvent in water. The counting chamber was a model Reference 0640710 supplied by Paul Marienfeld GmbH&Co.KG of Lauda-Königshofen, Germany. This unit could be used for counting bacteria cells in suspension but was ideal for judging any particle in suspension of a suitable size. The unit consisted of a precision glass base with engraved lines spaced 50 microns (µm) apart, crossing each other thus providing ruled squared areas of 50 x 50 µm. each side of the flat area were two raised parts where a glass slide is placed creating a depth of 100 µm.

[0056] Within 1 minute of manufacture, a drop of dispersion was placed on the counting-chamber after which a glass cover slide was placed on the chamber to trap a 100 µm thick film of dispersion over the ruled 50 µm calibration lines. The counting-chamber was immediately placed under an optical microscope. A 10 x and 40 x objective lens were initially used together with a Nikon model 995 digital camera set to full optical zoom. A Nikon adaptor model MDC with a 0.82 x factor lens was fitted to the microscope to allow the camera to be fitted. Finally, the 40 x microscope objective was used. Using the same setting, photos of the ruled calibrations of the empty counting chamber were taken as calibration reference. Photos were taken immediately after the dispersions were placed on the counting chamber, in any case within 2 minutes of manufacture of the dispersions.

[0057] The following dispersions were tested:

a) dispersion as produced in example 1 having 10% volume high-flash, dearomatized white spirit, the rest being water.

b) dispersion as a) having 5% volume high-flash, de-aromatized white spirit.

c) dispersion as a) but made by diluting a) 10 times by simple stirring with WHO standard soft water giving 1% volume high-flash, de-aromatized white spirit and photographed within 1 minute of dilution.

d) dispersion as a) but using 1 % volume of a mixture comprising 80% vol. high-flash, de-aromatized white spirit and 20% vol. orange terpene.

e) dispersion as a) but using 1% volume of a mixture comprising 78.5% vol. high-flash, de-aromatized white spirit and 19% vol. orange terpene plus 2.5% vol sorbitan monooleate.

[0058] Further data is provided in Table 1.

Example 6. Stability tests

[0059] A mechanical dispersion of high-flash, de-aromatized white spirit was produced as described in example 1 but with the component amounts adjusted to give 10% by volume of solvent in the dispersion, the rest being fresh water. The water used was industrial fresh water with a hardness measured as equivalent to 214 mg CaCO₃/1 (12° German Hardness).

[0060] The dispersion was tested for stability according to the WHO (World Health Organisation) Emulsion Stability Test Specification WHO/M/13.R4 Revised 10th December 1999 in standard "soft" water (a hardness of 34.2 mg/1 expressed as calcium carbonate hardness) prepared according to the WHO (World Health Organisation) Method WHO/M/29 (version approved 25.09.1989).

[0061] Into the 250 ml beaker was placed about 70 ml of WHO "soft" water then 20 ml of mechanical dispersion taken immediately after production was added to the beaker followed by topping up to 100 ml with WHO soft water.

[0062] The diluted dispersion prepared thus was immediately poured into a clean 100 ml measuring cylinder as part of test WHO/M/13.R4 whereby the appearance of the dispersion was observed over time.

Measurement

[0063] After 5 minutes standing at room temperature in the measuring cylinder the dispersion did not show any creaming, oiling or sediment formation.

[0064] Creaming is defined according to WHO/M/13.R4 as the formation, at the top or bottom of the dispersion, of a layer containing a proportion of the dispersed phase, namely solvent, higher than in the remainder of the emulsion. In practice, using a bright light source, a layer of creaming would show as a denser white layer than the normal dispersion as it would absorb or scatter more light. This may be detected by using a Turbiscan instrument supplied by the company Formulaction of L'Union, France. The Turbiscan principal is that a pulsed laser light source at 850 nm wavelength is applied to a cylindrical glass tube in which a sample of the original dispersion is held. A detector measures the directly transmitted light energy and a second synchronised detector measures the light that is back-scattered from the dispersion. The light source and detector are programmed to repeatedly scan down the glass cylinder and measure the transmitted and scattered light at intervals of 40 µm. This procedure is conducted over the time frame of the stability requirement. The mean particle size can be measured from 0.05 µm up to 1 mm with this technique. Particle migration (creaming), particle size variations (agglomeration), phase separation can all be measured.

[0065] Thus development of creaming would be measured as an increase in the back-scattered light and a decrease in the transmitted light.

[0066] Oiling is defined as formation at the top or the bottom of the dispersion of a liquid phase that is not miscible with water. In practice, an oiling layer would show as a clear liquid. Using the Turbiscan analyser, oiling would show as more transmitted light and less back-scattered light when the light beam is applied to that phase.

[0067] Sediment formation refers to any solids separation out and sinking to the bottom, which is detectable by the Turbiscan analyser as changes in the light scattering.

[0068] After 5 minutes standing at room temperature (23°C) there was no apparent oiling, creaming or sediment visible in the dispersion. However, after 15 minutes an "oiling" layer could be photographically documented.

Example 7. Effect of addition of the pre-dispersion

[0069] 10 ml of a product as described in example 1 was added to 400 ml of industrial fresh water in a glass beaker and made up to 500 ml with the same water. The water used had a total hardness equivalent to 240 mg/l CaCO₃. A magnetic stirrer was placed in the beaker and the speed so adjusted so that no significant quantity of air was drawn in by vortex action. After 5 minutes, the mixing was turned off and the mixture was allowed to stand. After 1 minute, using a fine glass pipette, samples of the diluted mixture were taken from the top, middle and bottom of the liquid and a small drop was placed on a particle counting chamber as described in example 4 for observation under a microscope.

[0070] Using a test according to the present invention the particle size and distribution were detected. It was seen that the particles of solvent were still evenly dispersed and within a size range where no particles bigger than 200 µm whereby the majority of the particles were smaller than 50 µm.

Example 8. Reduction in the use of conventional de-foamer by addition of the pre-dispersion according to the present invention

[0071] A pre-dispersion in water based on a mixture of 80% by volume of a hydrogen-treated petroleum distillate with an initial boiling point of 180°C plus 20% by volume of an orange-terpene oil derived from citrus fruit was prepared continuously using the basic procedure and equipment as described in example 1. The equipment was installed near the white-water circuit of a paper machine.

[0072] The water used was industrial fresh water from the paper mill supply measured to have a total hardness equivalent to 240 mg CaCO₃/l.

[0073] The pre-dispersion produced was fed continuously into the white-water I circuit of the paper machine into the white-water channel leading to the white-water silo. The amount of solvent thus added to the circuit in the form of a mechanical dispersion was 1.7 1/h (litres/hour).

[0074] The normal amount of de-foaming product used in the circuits of this paper machine was approximately 4 1/h. It was found that the de-foamer quantity used could be reduced down to a level of 2.1 1/h while remaining within the acceptable air content levels in the thin-stock and white-water system.

[0075] The use of the pre-dispersion in this way allowed the reduction in use of conventional de-foamer products and at the same time showed good cleaning action.

Example 9. Comparison pre-dispersion versus conventional product

[0076] A felt in a paper machine press-section regularly became contaminated with hydrophobic, sticky contamination meaning that it had to be off-line chemically washed with an alkaline cleaner every 3 or 4 days. The washing cycle lasted about 1 hour meaning that paper production was stopped for about 1.5 hours each time the felt had to be washed.

[0077] An on-line cleaning composition comprising 3% tensides and 77% high flash, dearomatized white spirit and 20 % orange terpene thus containing essentially no water was used whereby the product was applied continually over the felt width. A spray-bar with fanned spray-pattern nozzles was fitted on the inside of a press-felt in the press-section of a paper machine. The spray-bar was fitted with fanned-spray pattern nozzles every 20 cm. The designed throughput of each nozzle was 0.5 litres per minute at 3 bar water pressure. The spray-bar was placed so that the nozzles were approximately 20 cm from the surface of the felt to give an overlap in the individual spray pattern of 60% so that the coverage of the sprayed medium was uniform. Water was fed to the spray-bar at 3 bar pressure giving an amount of 2.5 litres per metre felt width per minute.

[0078] The tenside containing product was added using a small diaphragm pump at a rate of 5 ml per minute per metre width of felt meaning for the felt of 4.7 m wide a total volume of product of 23.5 ml/minute (or 23.0 ml/min as pure solvent).

[0079] With this treatment the paper machine could run up to 10 days without the felt needing to be off-line chemically washed.

[0080] A pre-dispersion according to example 2 was produced. The concentration of solvent was adjusted to be the same as in the comparative test described above.

[0081] Thus the total amount of active ingredient applied was 5 ml/min per metre felt width but in a form finely mechanically dispersed in water.

[0082] With the treatment according to the present invention using mechanically dispersed solvent with no added tenside, the paper machine could run up to 14 days without the felt needing to be off-line chemically washed.

Table 1

	Exp.1	Exp.2	Exp.3	Exp.4	Exp.5 a	Exp.5 b	Exp.5 c	Exp.5 d	Comp.Exp.5
Substance	White spirit	80% white spirit 20% or ange terpene	Rape-seed oil methyl ester "bio- diesel"	White spirit	White spirit 10%	White spirit 5%	White spirit dispersion diluted 10 times	1% volume pa. 80% white spirit 20% orange terpene	1 % volume 78.5% white spirit 19% orange terpene 2.5% sorbitan monooleate
Preparation	Pumps, static mixer, back-pressure valve	Pumps, static mixer, back- pressure valve	Pumps, static mixer, back- pressure valve	Pumps, micro emulsifier	Pumps, static mixer, back- pressure valve	Pumps, static mixer, back-pressure valve	Pumps, static mixer, back-pressure valve	Pumps, static mixer, back-pressure valve	Pumps, static mixer, back-pressure valve
Optical impression	Milky white	Milky white	Milky white	Milky white	Milky white	Milky white	Translucent, milky white	Translucent, milky white	Translucent, milky white
Average particle diameter (µm)	10	8	14	13	9	10	12	11	3
Stability 15 min	+	+	+	+	+	+		+	+
Decomposition after 60 min	Clear, upper oil layer	Clear, upper oil layer	Noticeable upper oil layer	Clear, upper oil layer	Clear, upper oil layer	Clear, upper oil layer	Clear, upper oil layer	Clear, upper oil layer	Slight upper oil layer, 2 milky lower phases
Creaming/oiling upon dilution After 60 min	Oiling	Oiling	Slight oil ing	Oiling	Oiling	Oiling	Oiling	Oiling	Slight oiling and creaming

Table 2

(1) Fatty triglycerides, and the fatty acids, alcohols, and dimers derived therefrom:

Beef tallow.

Castor oil.

Coconut oil.

Corn oil.

Cottonseed oil.

Fish oil.

Lard oil.

Linseed oil.

Mustardseed oil.

Palm oil.

Peanut oil.

Rapeseed oil.

Ricebran oil.

Soybean oil.

Sperm oil.

Tall oil.

(2) Fatty triglycerides, and marine oils, and the fatty acids and alcohols derived therefrom (paragraph (d)(1) of this section) reacted and/or blended with one or more of the following, with or without dehydration, to form chemicals of the category indicated in parentheses:

Kerosine

Mineral oil

Naphtha

Odorless light petroleum hydrocarbons

Oleyl alcohol

Petrolatum

Pine oil

Siloxanes and silicones, dimethyl, methylhydrogen, reaction products with polyethylene-polypropylene glycol monoallyl ether (CAS Reg. No. 71965-38-3)

Wax, petroleum, Type I and Type II.

Wax, petroleum (oxidized).

Wax (montan)

Cyclohexane

Dimers and trimers of unsaturated C 18 fatty acids derived from animal and vegetable fats and oils.

Tall oil.

Fats and oils derived from animal,marine, or vegetable sources:Fatty acids derived from animal,marine, or vegetable fats andoils, and salts of such acids,single or mixed, as follows: Aluminum,Calcium,Magnesium,Zinc.

Methyl esters of fatty acids derived

from animal, marine, or vegetable fats and oils.

Methyl oleate

Methyl palmitate

Mineral oil

Odorless light petroleum hydrocarbons

Tall oil fatty acids...................

Tallow fatty acids, hydrogenated or sulfated.

Table 3

	Exp.9	Exp.10
Composition	77% white spirit	79.4% white spirit
	20% orange terpene	20.6% orange terpene
	3% tensides
Paper machine run time without need for off-line chemical felt washing	10 days	14 days

Example 10

[0083] The pre-dispersion according to experiment 5d was compared with the mixture according to comparative experiment 5. The pre-dispersion and the mixture were added (in equal amounts) to a pilot plant, which simulated the turbulences present in paper machines. In the case of the pre-dispersion according to experiment 5d the amount of bubbles was significantly lower than in the case of the mixture according to comparative example 5. Additionally the necessary amount of defoamer agent for a reliable cleaning could be reduced by a factor of 1.7.

Claims

1. Method for dispersing at least one substance in a water-containing system including the following steps

a) addition of at least one substance having a solubility in deionised water at 20°C of maximum 0.05 mol/l each to water;

b) dispersion of the at least one substance without the use of a tenside by supply of energy such that a metastable pre-dispersion having a mean particle size of from 1 µm to 1 mm is formed and the resting pre-dispersion is stable for a minimum of 3 minutes and a maximum of 60 minutes and thereafter the pre-dispersion decomposes;

c) addition of the pre-dispersion prior to decomposition to a water-containing system.

2. Method according to claim 1, wherein the supply of energy in step b) is selected such that the pre-dispersion has a stability of at least 5 minutes according to the World Health Organisation Emulsion Stability Test Specification WHO/M/13.R4 revised 10^th December 1999 in water having a hardness of 34.2 mg/l calcium carbonate according to WHO method WHO/M/29 version approved 25^th September 1989.

3. Method according to claim 1 or 2, wherein the mean particle size of the pre-dispersion is within the range of 2 µm and 500 µm.

4. Method according to any of the preceding claims, wherein the mean particle size of the pre-dispersion is within the range of 5 µm and 100 µm.

5. Method according to any of the preceding claims, wherein the energy addition in step b) takes place through at least one of the following provisions

- mechanical means including shaking, beating, stirring and/or turbulent mixing

- injection of the at least one substance into the aqueous mixture or the other way around

- creation of vibration and/or cavitation in the mixture through pressure change and/or the effect of ultrasonic devices

- combining the separated components in a static-mixer and/or micro static-mixer.

6. Method according to any of the preceding claims, whereby the at least one substance having a solubility in deionised water at 20 °C of maximum 0.05 mol/1 each is selected from, hydrogen-treated petroleum distillate fraction, white spirit, including high-flash dearomatized white spirit, paraffin oils, edible fats and edible oils, silicone oils, aliphatic alcohols with 8 to 26 carbon atoms, fatty acid esters, ethylene oxide and/or propylene oxide oxylated derivatives of fatty acid esters, waxes derived from mineral oils including paraffin waxes, natural waxes, etheric oils and terpenes of natural origin including orange terpene.

7. Method according to any of the preceding claims, whereby the water-containing system comprises water and optionally at least one substance selected from natural and/or synthetic fibres and fines thereof, natural and/or synthetic fillers and/or pigments and/or solids, natural and/or synthetic polymers and resins, inorganic salts, suspended or surface-adhering micro-organisms, substances used in paper and pulp manufacture.

8. Method of any of the previous claims, whereby the water-containing system comprises a paper machine circuit, a circuit in a fibrous-pulp producing plant, a waste water circuit, an industrial fresh water preparation plant and including vessels and pipe-work used in any of these systems.

9. Method of any of the previous claims, whereby the addition according to step c) occurs before a maximum of 15 minutes.

10. Pre-dispersion comprising
at least one substance having a solubility in deionised water at 20 °C of maximum 0.05 mol/l each and water,
whereby the mean particle size of the pre-dispersion is from 1 µm to 1 mm, and
whereby the pre-dispersion is stable for a minimum of 3 minutes and a maximum of 60 minutes, and
wherein the pre-dispersion does not contain a tenside.

11. Pre-dispersion according to claim 10, wherein the pre-dispersion has a stability of at least 5 minutes according to the World Health Organisation Emulsion Stability Test Specification WHO/M/13.R4 revised 10^th December 1999 in water having a hardness of 34.2 mg/l calcium carbonate according to WHO method WHO/M/29 version approved 25^th September 1989.

12. Pre-dispersion according to claims 10 or 11, wherein the mean particle size of the pre-dispersion is within the range of 2 µm and 500 µm.

13. Pre-dispersion according to any of claims 10-12, wherein the mean particle size of the pre-dispersion is within the range of 2 µm and 500 µm.

14. Pre-dispersion according to any of claims 10-13, wherein the at least one substance having a solubility in deionised water at 20 °C of maximum 0.05 mol/l each is selected from hydrogen-treated petroleum distillate fraction, white spirit, including high-flash dearomatized white spirit, paraffin oils, edible fats and edible oils, silicone oils, aliphatic alcohols with 8 to 26 carbon atoms, fatty acid esters, ethylene oxide and/or propylene oxide oxylated derivatives of fatty acid esters, waxes derived from mineral oils including paraffin waxes, natural waxes, etheric oils and terpenes of natural origin including orange terpene.

15. Pre-dispersion according to any of claims 10-14, wherein the total amount of the substance or substances having a solubility in deionised water at 20 °C of maximum 0.05 mol/l each is below 33 vol%.

16. Pre-dispersion obtainable by a process according to any of claims 1-9.

17. Use of the pre-dispersion according to any of claims 10 - 16 as a cleaning agent in industrial plants.

18. Use of the pre-dispersion according to any of claims 10 - 16 as defoamer, de-aerator, adhesion inhibitor against stickies and/or cleaner in the paper and pulp industry, the foodstuffs industry or in waste-water treatment.