WO2007138414A1

WO2007138414A1 - Device for automatic filter closure

Info

Publication number: WO2007138414A1
Application number: PCT/IB2007/001334
Authority: WO
Inventors: Bernhard Keller; Martin Gehri; René Pellaux
Original assignee: Preentec Ag
Priority date: 2006-05-24
Filing date: 2007-05-23
Publication date: 2007-12-06
Also published as: EP2086888A1

Abstract

The invention relates to a device for the automatic closure of used filter cartridges that can be replaced in filter systems. The device comprises a fluid impermeable compartment into which at least one material body capable of expanding is inserted.

Description

Device for automatically closing filter cartridges

Technical area

The invention relates to a device for automatic closure of used, replaceable filter cartridges in filtration systems. Such filtration systems with replaceable filter cartridges are used to e.g. Free water from organoleptically interfering impurities to reduce water hardness, kill microorganisms, or to remove toxins such as arsenic compounds from liquids.

The binding of the substances to be removed is achieved by a filling of the filter cartridges with filter materials such as activated carbons, ion exchangers or specific sorbents such as arsenbindenen sorbents. The filter materials have a limited capacity for receiving the substances to be removed from the liquids and are therefore to be used only for a limited number of purification cycles.

In order to prevent the users of the filtration systems, the filter cartridges whose capacity is exhausted continue to use, the patent US 5,900,138 has been proposed to equip water filtration systems with counters. This counter indicates when the maximum number of purification cycles has been reached and may optionally be equipped to mechanically block the filter when the maximum number of purification cycles is reached. The main drawback of such systems is that the counter can be reset by deliberate or accidental manipulation of the user, thus allowing the filter to continue to be used, with all the risks arising therefrom. A similar system has been described in US Pat. No. 4,895,648. In this case, after inserting a new filter cartridge, a marker disc on which the calendar months are noted is rotated so that the month of the filter change can be recorded. Obviously, the disadvantages mentioned for counter systems are not remedied by such systems. In the patent US 4,686,037 a filter system is proposed, the impurities in a prefilter field. The color of this prefilter is then periodically compared by the user with a reference to indicate when the filter capacity is exhausted. It is obvious that such a system can not preclude a faulty condition by the user.

One approach to solving these problems is to use an automatic closure system that closes the filter cartridge after a defined number of cleaning cycles so that intentional or random manipulation of the closure system by the user can be ruled out. The patents US 4,918,426 and US 5,089,144 describe electronic closure systems in which a valve is closed after a fixed flow. Other patents, such as US 3,503,507, US 3,586,018, US 4,681,677, US 4,769,135, US 4,698,164 or US 4,772,386, describe mechanical closure systems. Electronic and mechanical closure systems in principle meet the desire for an automatic closure that can not be intentionally or unintentionally mis-manipulated. However, such systems are complex, relatively large and expensive, and thus of limited use for a disposable item, such as an interchangeable filter cartridge for household use. In the patent US 6,428,687 a closure system was presented, for which the above-mentioned disadvantages do not apply. It consists of a passage which is kept free by a spacer in the form of a water-soluble material. The material dissolves slowly when using the filter, when it is completely dissolved, the passage closes. Potential advantages and disadvantages of such a system depend on the choice of material, which has not been specified in detail in US Pat. No. 6,428,687. In any case, it must be noted that the material is slowly dissolved in the water, and therefore enters the filtrate. In addition, it can be assumed that the passage narrows continuously and is not closed within a short time.

The object of the present invention is thus to provide a simple and cost-effective closure system without the aforementioned disadvantages. Description of the invention

The present invention relates to a device for automatic closure of used, replaceable filter cartridges in filtration systems according to claim 1. Preferred embodiments are defined in the dependent claims 2 to 8.

The inventive solution is based on the idea of an automatic closure system, which closes the filter cartridge after a defined number of cleaning cycles so that manipulation of the closure system is excluded by the user. An inventive device for the automatic closure of spent filter cartridges in filtration systems in the sense of the invention described herein consists of one or more bodies of material, which are filled into a compartment inside or outside the filter cartridge. The compartment is suitable for liquids such as e.g. Water permeable, but impermeable to the material body. Upon contact with water, the material bodies swell or swell and increasingly fill the compartment. As a result, the flow of liquids is reduced and finally completely prevented. It is obvious to the person skilled in the art that the circumstances described here apply to liquids in general, ie in particular also to water and aqueous systems such as solutions and mixtures.

Material bodies in the sense of the present invention are characterized by their shape, their material composition and their swelling and / or swelling behavior.

The shape of the body of material may be varied, but should be such that the body of material can not escape from the compartment. Furthermore, the size of the material body should be smaller than the passages in the compartment. It should also be noted that the shape and size of the material body influences the dynamics of the swelling behavior of the material body after contact with liquids, since material bodies having a large surface swell faster than those having a small surface area. Preferred embodiments of the material body in the context of the invention are discs, balls and other regular body but also irregularly shaped body such as granules. Further preferred are discs with a diameter of 0.1-5 cm and a thickness of 0.1 - 2 cm or balls with a diameter of 0.1 - 2 cm and granules with a grain of 0.2 - learn.

The material composition of the material body according to the invention comprises all materials which swell on contact with water and thereby change their shape only so far that they can not escape from the compartment. Preferred materials are polymeric materials. Further preferred polymers are crosslinked hydrophilic polymers. Further preferred materials are polymers which are referred to in the specialist literature as superabsorptive polymers (SAPs). Preferred SAPs are cross-linked polymers based on polyacrylamides, polyacrylic acids, starch-polyacrylic acid graft polymers, polyethylene maleic anhydride copolymers

Polyisobutylenmaleic anhydride copolymers and mixtures and copolymers of these polymers.

The swelling behavior of the material bodies is characterized by the rate of swelling and by the amount of water absorbed at equilibrium. These parameters are influenced by the shape and material composition of the material body. The temperature of the liquid, the pH value, the water hardness and the presence of other impurities can also influence the swelling behavior. In addition, the swelling behavior can be changed by modifying substances. Modifying substances in the context of the invention are all chemical substances or substance mixtures which influence the rate of swelling of the material bodies and / or the amount of liquid absorbed by the material body in the state of equilibrium. Preferred modifying substances in the context of the invention are salts and polyelectrolytes. Preferred salts are the salts of polyvalent metal ions. Further preferred salts of polyvalent metal ions are the salts of alkaline earth metals, in particular the salts of divalent magnesium and calcium ions. In a preferred application of the invention, the modifying substances are retained by absorption in the bodies of material. A preferred swelling behavior in the context of the invention is characterized in that the amount of liquid absorbed in the equilibrium state exceeds the dry mass of the material body by a factor of 2-1000. A preferred threshold speed in the sense of the invention is defined by the period of time after which the material body fills the compartment so far through the contact with the liquid flowing through the filter that the liquid flow is stopped. From this period of time, the maximum amount of liquid flowing through the filter can be calculated at a known average flow rate. This allows adaptation of the maximum flow rate to the capacity of the filter material. Preferred periods of time within the meaning of the invention are in the range of 100 to 2000 minutes, further preferred time periods of 300 to 800 minutes. Since superabsorbent polymers often swell significantly faster, the use of modifying substances is necessary to achieve such long periods of time. Modifying substances such as magnesium and calcium ions which are absorbed on the material bodies can significantly slow down the rate of swelling. However, if the material bodies are in contact with liquid for longer periods of time, the modifying substances are continuously removed by diffusion from the material bodies and the swelling speed increases. In addition to the modifying substances, it is often necessary to use material bodies with a relatively low surface area to volume ratio to achieve the desired time periods. The modifying substances can additionally achieve a memory effect. This memory effect is characterized in that the material bodies which have been treated with modifying substances, when in contact with liquid slowly release the modifying substances to the liquid. Now, if the contact of the material body is interrupted with the liquid, the material body begins to dry out. If the completely or partially dried material body is now contacted again with liquid, they swell quickly to the state before drying, that is, the material body treated with modifying substances remembered the state before drying.

A compartment in the sense of the present invention is a space segment within the filter cartridge (Figure 1), which has a defined volume and is characterized in that it is permeable to liquids, during which the material bodies are enclosed in the compartment. In addition, the compartment is mounted in the filter cartridge in a way that all liquid to be filtered must flow through the compartment. Preferably, the compartment consists of a space segment whose upper and lower boundary consists of a slot or screen plate whose openings are smaller than the material body, and whose lateral boundary forms the filter cartridge. The volume of the compartment depends on the amount and swelling behavior of the material bodies, and can be varied over a wide range to achieve a desired time to closure of the filter. In a specific embodiment of the invention, the compartment is identical to the outer boundaries of the filter cartridge. In another specific embodiment of the invention, the compartment is located above or below or within the filter material within the filter cartridge.

In addition to the device described, the invention further relates to a filtration system comprising a filter cartridge and the inventive device according to claim 9 and a method for automatically closing a filter cartridge in a filtration system according to claim 1 1. Furthermore, the invention relates to the use of a swellable material body for automatic closure of a Filter cartridge in a filtration system according to claim 12.

embodiments

Example 1: Synthesis of material bodies of acrylamide / maleic acid

Ig acrylamide was dissolved in ImI aqueous solutions of 0, 20, 30, 40, 50, 60mg maleic acid and treated with APS (25%) 50microl and polymerized at 50 ⁰ C for Ih. The resulting polymer was cut into pieces (5-10 mm) and rinsed thoroughly in water (demin) for 12 hours and then freed from residual monomers by Soxhlet distillation for 2 hours. Subsequently, the hydrogel particles were dried at 40 ° C in an oven to constant weight. The residual monomer content of the free acid was determined titratively with NaOH (0.05M) against phenolphthalein. If the result was positive, the washing steps including Soxhlet extraction were repeated. Example 2 Synthesis of Material Structures from n-Vinylpyrrolidone / Itaconic Acid (Methylenesuccinic Acid)

2 ml of n-vinyl-2-pyrrolidone was dissolved in ImI aqueous solution of 0, 60, 120, 180 and 240 mg of itaconic acid and treated with 0.25% (v / v, EGDMA / VP) of EGDMA. The resulting solution was polymerized by addition of 50microl APS (25%) at 50 ⁰ C for Ih. The polymer was cut into pieces of 5-10 mm, or plates and washed extensively during 12h, it is eliminated in connection by means of Soxhlet extraction of residual monomers and in the oven at 40 ⁰ C until constant weight. The residual monomer content of the free acid was determined titratively with NaOH (0.05M) against phenolphthalein.

Example 3: Synthesis of material bodies of acrylamide / sodium acrylate by direct polymerization from the monomers

1.0g, 1.5g, 2g, or 2.5g acrylic acid sodium salt and 9g, 8.5g, 8g or 7.5g acrylamide and 40, 50, 80, or 120mg N, N'-methylenebisacrylamide were dissolved in 50ml H ₂ O and 200microl TEMED added , The resulting solution was polymerized by addition of 50microl APS (25%) at 50 ⁰ C for Ih. The polymer was cut into pieces of 5-10 mm or in plates and thoroughly washed for 12 h, then freed of residual monomers by means of Soxhlet extraction and oven-dried at 40 ^° C. to constant weight. The dried hydrogel particles or plates were tested on the one hand by titration (NaOH 0.05M / phenolphthalein) and on the other hand by extraction and then GC-MS on their residual monomer content.

Example 4: Synthesis of acrylamide / sodium acrylate bodies by hydrolysis of cross-linked polyacrylamide

10 g of acrylamide were taken up in 50 ml of H ₂ O and admixed with 40, 50, 80 or 120 mg of N ₅ N ¹ -methylenebisacrylamide. The solution was 200microl TEMED and APS 50microl (25%) was added and polymerized for Ih at 50 ⁰ C. The polymer was cut into 5-10 mm pieces or slabs and washed vigorously for 12 hours. Subsequently, the particles were stirred in 5% NaOH at various temperatures (30 ⁰ C - 80 ⁰ C) for 2h to 24h. The resulting particles were washed thoroughly for 12 h and then freed of residual monomers by means of Soxhlet extraction and dried in the oven at 40 ° C to constant weight. The analysis of the residual monomers was carried out analogously to Example 1.

Example 5: Synthesis of material bodies of acrylamide / sodium acrylate / agar

1.0g, 1.5g, 2g, or 2.5g acrylic acid sodium salt and 9g, 8.5g, 8g or 7.5g acrylamide, and 40, 50, 80, or 120mg N, N'-methylenebisacrylamide were dissolved in 10ml H ₂ O and washed with 1% aqueous Agar solution mixed at 60 ° C and mixed with 200microl TEMED. The resulting solution was polymerized by addition of 50microl APS (25%) at 60 ⁰ C for 3 h. The polymer was cut into pieces of 5-10 mm or in plates and thoroughly washed for 12 h, then freed of residual monomers by means of Soxhlet extraction and oven-dried at 40 ^° C. to constant weight. The dried material bodies were tested analogously to Example 1 for their residual monomer content.

Example 6: Treatment of the material bodies with modifying substances and resulting influences on the swelling behavior

The material bodies produced according to Examples 1-5 were modified in their Schwell behavior to have a long-term swelling behavior with a logarithmic course. For this purpose, in each case 5 g of the unmodified material bodies were stirred in one liter of an aqueous solution of magnesium or calcium salts of variable concentrations for 48 h. It was then filtered, washed briefly and dried in an oven at 40 ⁰ C to constant weight. Thereafter, the dried material bodies were contacted with aqueous solutions and the swelling behavior was analyzed as a function of the material body, the temperature, the water hardness, the chlorine content. Exemplary values for the amount of aqueous solutions absorbed by differently modified material bodies (50 mg polyacrylamide / sodium polyacrylate synthesized according to Example 4), granulated, sieved fraction 2 - 3.15 mm) absorbed in the period of 580 minutes (determined by the increase in mass of the material bodies) are listed in Table 1. Table 1

(1) Type / amount of salt used to modify 5 g of material body in 1 liter of aqueous solution.

(2) Water hardness in German degrees of hardness

Threshold curve of the materials

Example 7: Use of the modified material bodies in a water filter

Material MgCl ₂ 100 and MgCl ₂ 167 were added in different amounts to the filter compartment, the filter being closed at an average flow time of 5 min at a water hardness of 18 dH as follows: MgCl ₂ 100 750 mg 90 minutes after 18 Liters closed

MgCl ₂ 100 900 mg closed 75 minutes after 15 liters

MgCl ₂ 167 1200 mg closed 75 minutes after 15 liters

MgCl ₂ 167 1 100 mg closed 120 minutes after 24 liters

RT RT 5-9 ° C

35 ° C

Example 8: Swelling behavior of the material body as a function of the temperature, the water hardness and the size of the material body

Example 9: Regression of the ° ie curves

Example 10: Influence of temperature

RT

Example 1 1: Influence of water hardness

Example 12: Influence of MgCl ₂ concentration

-90 10 110 210 310 410 510 610 710 810 910 t (min)

Example 13: Influence of the CaCl ₂ concentration

Claims

claims

1. A device for the automatic closure of spent, interchangeable filter cartridges in filtration systems, wherein the device comprises a liquid-permeable compartment, characterized in that in the compartment at least one schwellfahiger material body is included.

2. Device according to claim 1, characterized in that the material body consists of polymers, preferably cross-linked, hydrophilic polymers.

3. A device according to claim 1 or 2, characterized in that the material body has the shape of a regular body, preferably in the form of a ball or a disc.

4. Device according to claim 1 or 2, characterized in that the material body has the shape of an irregular body, preferably granules.

5. The device according to claim 3, characterized in that the material body is a ball with a diameter of 0.1 to 2 cm.

6. The device according to claim 3, characterized in that the material body is a disc with a diameter of 0.1 to 5 cm.

7. The device according to claim 4, characterized in that the material body is granules with a grain size of 0.2 to 1 cm.

8. The device according to claim 2, characterized in that the material body consists of at least polymers and modifying substances.

9. Filtration system comprising a filter cartridge and the device according to one of claims 1 to 8.

10. Filtration system according to claim 9, wherein the device is arranged inside or outside the filter cartridge such that it is traversed by the liquid to be filtered.

11. A method for automatically closing a filter cartridge in a filtration system, characterized in that a liquid is passed through at least one compartment, in which at least one swell capable material body is included.

12. Use of a swellable material body for automatic closure of a filter cartridge in a filtration system.