WO2010076366A1

WO2010076366A1 - Adsorbent coating

Info

Publication number: WO2010076366A1
Application number: PCT/ES2009/070640
Authority: WO
Inventors: Javier SOLER GARCÍA; Jaime Ara Aracil; José Antonio DÍAZ AUÑON
Original assignee: Carbongen, S.A.
Priority date: 2008-12-31
Filing date: 2009-12-30
Publication date: 2010-07-08
Also published as: ES2342142B1; ES2342142A1

Abstract

The present invention relates to an adsorbent coating comprising, in percentage by dry weight of the final product: 10-90% mineral filler; 10-90% water-based resin acting as a binder; 0.1-25% thickener; and water; wherein the filler may be activated carbons, activated carbon fibres, carbon black, graphites, zeolites, clays, amorphous silicas, amorphous aluminas, amorphous metal oxides, ion-exchange resins, and combinations thereof, and to the use thereof for obtaining tissues having adsorbent and/or antistatic properties, and surfaces having adsorbent and/or antistatic properties.

Description

ADSORBENT COATING

TECHNICAL FIELD OF THE INVENTION

The present invention falls within the field of coatings used as paints for coating walls and other surfaces, such as coatings comprising water-based resin, and as a finished fabric.

STATE OF THE PRIOR ART OF THE INVENTION Activated carbon has been used for many years in water filtration and purification systems. Amorphous carbon ("soot" or carbon black) is added to the rubber to improve its mechanical properties. It is also used in the formation of electrodes (for example, batteries, as graphite electrodes). On the other hand, carbon fibers are added to resins (polyester, epoxy or any other nature) to form composites of high mechanical strength and low weight. Today, activated carbon is also used in technical textiles used in water filtration systems, odor absorption and air purification systems, protective clothing, gas masks, insoles, medical uses, etc., such as fabrics made of threads that are 100% carbon fiber, from the Spanish company Carbongen, SA (Alicante), threads that they activate. This material is very appropriate in air and liquid filtration systems.

Other applications of activated carbon are in insoles for footwear, both in use in insoles and lining throughout the interior of the footwear, as well as in any other possible way, coating on electrodes of fuel cells (such as carbon black in this application ), as electrodes in supercapacitors or fuel cells - in the form of carbon fabrics in this case -. US-6,030,698, published on 02/29/2000, refers to a carbon fiber composite activated with phenolic resins as a binder for the manufacture of adsorbent monoliths (bricks) for use in filtration.

Patent application WO-03073011, published on 04/09/2003 refers to a composite in the form of activated carbon sheets and other adsorbent materials that it uses as a low density polyethylene (LDPE) binder for use as a filtering agent.

Patent application WO0170391, published on 02/29/2000, refers to a composite in the form of sheets containing activated carbon and ion exchangers for use in filtration. Patent application US2008106850, published on 05/08/2008, refers to an electrode for activated carbon supercapacitors mixed with a polymeric binder forming a film that is the active phase. Patent application KR20080007789, published on 01/23/2008, refers to a coating of activated carbon and the form of application.

Patent application EP1936642, published on 06/25/08, refers to a coating of activated carbon in powder form mixed with an ion permeable compound for supercapacitor electrode.

Patent application JP10017847, published on 01/20/1998, refers to a coating of powdered catalysts (silver and titanium oxide) mixed with adsorbents (clays, zeolites, activated carbon) with anti-odor and biocidal function that can coat metals, paper, fabrics, etc.

US-3,912,538, published on 10/14/1975, refers to the use of carbon fibers for the manufacture of fuel cell electrodes, consisting of a composite of fiber, graphite and polymer as a binder. Patent application GB2117746, published on 12/29/1981, also refers to a composite of fiber, graphite and polymer as a binder for the manufacture of fuel cell electrodes. Patent GB1347534, published on 02/27/1974, refers to the use of a carbon fabric as a support for fuel cell electrodes.

While the state of the art refers to the use of carbon in a plurality of applications, the inventors have not been aware of the use prior to the present invention, of charges of activated carbon and / or other adsorbent mineral materials, whether zeolites, clays, amorphous silicas, amorphous aluminas, oxides of titanium, zinc (and / or other metals) amorphous etc. Nor are non-mineral materials known as ion exchange resins in coatings, such as paints used to coat walls or other surfaces, or as a finish on fabrics, or as a finish that provides electrical or antistatic properties. That is, there were no known uses in which the inherent potential of the charge (henceforth mineral charge) was used to confer certain adsorption characteristics and / or electrical or antistatic properties to such surfaces and / or objects. The electrical or antistatic properties are useful, for example, with polyester or wool fabrics, with a high capacity to accumulate static charge. These electrical properties could also be applied to other materials such as sole rubbers, which accumulate a lot of static charge. In particular, activated carbon fibers, carbon blacks or graphite, have the property of conferring these antistatic properties.

DESCRIPTION OF THE INVENTION The present invention aims to take advantage of the inherent potential of porous materials to get coatings that have the property of purifying gases and liquids. Activated carbon has a large specific surface area (500-3000 m ² / g), being the most porous material that exists, on whose surface a large amount of chemical compounds are physically adsorbed, which is why it serves to achieve this objective). These coatings are used as paint for coating walls or other surfaces, and / or as a finish on fabrics. In addition, it is also intended to take advantage of the electrical properties of some carbonaceous materials to achieve coatings having electrical properties, to be used on walls and / or other surfaces and fabrics. The adsorbent coating of the invention comprises the following components: a mineral charge, in a percentage by weight, dry of the final product between 10-90% a water-based resin, which will act as a binder, in a percentage by weight, dry of the final product between 10-90%, a thickener, in a dry weight percentage, of the final product between 0.1-25%, water, optionally, at least one additive selected from conventional additives itself, such as, by For example, one or more of the following: crosslinkers, pigments, surfactants, etc. According to particular embodiments, in the case of wall and other surface coverings, for curing under ambient conditions, the coating also includes crosslinking additives.

The mineral load can be selected from activated carbons, activated carbon fibers, carbon black, graphites and / or other adsorbent mineral materials, be they zeolites, clays, amorphous silicas, amorphous aluminas, titanium oxides, zinc (and / or others metals) amorphous etc, non-mineral materials such as ion exchange resins and combinations thereof. The coating of the invention can be used for at least four types of objects: adsorbent surfaces, antistatic surfaces, adsorbent fabrics and antistatic fabrics.

According to a particular embodiment of the invention, for the surface coating, preferably activated carbon can be used as a charge. According to a further particular embodiment of the invention, for finished fabrics, preferably activated carbon fiber can be used as a filler.

According to a further particular embodiment of the invention, for finishing with electrical properties, it can preferably be used as carbon black charge, activated carbon fiber or graphite.

According to the invention to determine the amount of resin, thickener or mineral filler in the dry matter on which these values are based, water is ignored in the calculations.

The amount of water is a trivial fact that has no relevance since percentages of the other components are given in dry weight.

In a particular embodiment of the invention, the coating comprises:

- 10 to 90%, preferably 50 to 90%, and more preferably 60 to 80%, by weight based on the total dry weight of the final mineral loading product,

- 10 to 90%, preferably 10 to 50%, and more preferably 10 to 25%, by weight based on the total dry weight of the final product, of water-based resin;

0.1 to 25%, preferably 1 to 20%, and more preferably 5 to 15%, by weight based on the total dry weight of the final product, of thickener; - 0 to 5%, preferably 0 to 1%, and more preferably 0 to 0.5%, by weight based on the total dry weight of the final product, of at least one additive.

The resin that acts as a binder can be a hot melt polymer, such as polyethylene, polypropylene, or polystyrene, solvent soluble polymer such as polyvinylidene difluoride (PVDF).

Examples of resins are acrylic resins, polyolefin, epoxy or fluorocarbon resins, these resins being chosen based on the specific application of the coating or finish and the characteristics that it is desired to confer to the surface or the object being coated. Preferred resins for surface coating of the present invention are acrylic, and fluorocarbon, and more particularly acrylic. Preferred resins for fabric finishes are acrylic and fluorocarbon, and more particularly acrylic. The thickener can be a natural thickener (such as a thickener of vegetable origin, either starch or derivatives thereof) or synthetic itself (such as a petroleum derivative, such as ethylene oxide) of those used in the coatings sector, such as, for example, by choosing the, or the, thickeners depending on the specific application of the coating or finish and the characteristics that it is desired to confer to the surface or to the object that is coated. Preferred thickeners for surface coating of the present invention are synthetic and semi-synthetic, and particularly synthetic.

Preferred thickeners for fabric finishes are synthetic and semi-synthetic, and particularly synthetic, and more particularly, synthetic. According to a particular embodiment the coating comprises:

- 60 to 80%, by weight, based on the total dry weight of the final product, mineral load, - 10 to 25%, by weight, based on the total dry weight of the final product, of water-based resin;

- 5 to 15%, by weight based on the total dry weight of the final product, of thickener;

- 0 to 10%, by weight based on the total dry weight of the final product, of at least one additive.

According to a further particular embodiment the coating comprises:

- 60 to 80%, by weight, based on the total dry weight of the final product, of the mineral load selected from activated carbons, activated carbon fibers, carbon black, graphites, zeolites, clays, amorphous silices, amorphous aluminas, metal oxides amorphous, ion exchange resins, and combinations thereof,

- 10 to 25%, by weight based on the total dry weight of the final product, of water-based resin selected from acrylic resins, polyolefin resins, epoxy resins and fluorocarbon resins;

- 5 to 15%, by weight based on the total dry weight of the final product, of thickener selected from natural thickeners derived from cellulose, proteins and synthetic thickeners derived from petroleum;

According to a further particular embodiment the coating comprises:

- 60 to 80%, by weight based on the total dry weight of activated carbon fiber,

- 10 to 25%, by weight based on the total dry weight of the final product, of acrylic resin; - 5 to 15%, by weight based on the total dry weight of the final product, of ethylene oxide as a thickener. According to a further particular embodiment the coating comprises:

- 60 to 80%, by weight based on the total dry weight of activated carbon,

- 10 to 25%, by weight based on the total dry weight of the final product, of acrylic resin;

- 5 to 15%, by weight, based on the total dry weight of the final product, of a semi-synthetic thickener with a cellulosic base.

According to a further particular embodiment the coating comprises:

- 60 to 80%, by weight based on the total dry weight of a mineral load selected between activated carbon fibers and carbon blacks,

- 5 to 15%, by weight based on the total dry weight of the final product, of ethylene oxide as a thickener. s coatings according to an embodiment of the present invention can be obtained by a process that, in general, comprises the following steps: The thickener is added to the water, stirring vigorously and experiencing how the viscosity of the solution increases and swells.

At the same time, the mineral load is dispersed in water, and if necessary, a surfactant (additive, for example ox-heel) will be added to facilitate dispersion. Both solutions are mixed. The binder is then added, stirring until complete homogenization.

Finally, other additives are optionally added, such as crosslinkers (curing accelerators), pigments (to modify the color), etc. (vi) It is applied on the surface to be treated Depending on the application and the binder, it dries and cures in some conditions or others.

Coatings in accordance with the present invention have the advantages of granting filter or electrical properties to fabrics, walls, etc. in a simple, versatile and economical way.

For example, woven or non-woven fabrics can be obtained with adsorbing odors, which can be used in footwear, sheets, pillows, undergarments, etc. Another example would be to cover the walls of rooms that by their application accumulate bad smell, such as a boiler room, warehouses, or furniture or storage objects, such as shoemakers, garbage dumps and even in a refrigerator or refrigerator, or to obtain rooms especially clean of contaminants, such as clean rooms, museums and / or where electronic objects are stored.

Another example would be to provide fabric with unsightly properties, for example polyester or wool, or on walls and floors to protect electronic material from static accumulation.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a diagram of the parts of the footwear in which the coating of the invention can be applied.

Figure 2 shows a photograph of the sample of example 1.

Figure 3 is a photograph of the scanning electron microscope (SEM) of the sample prepared in example 3.

Figure 4 shows a photograph of the sample prepared in example 3.

Figure 5 shows a photograph of the sample prepared in example 5. EMBODIMENTS OF THE INVENTION

Next, non-limiting examples of examples to illustrate possible embodiments and particular aspects of the present invention are described.

Example 1: Activated carbon fiber and acrylic resin adsorbent. Applied on a fabric for possible application as an adsorbent or filter layer. It was used:

- a 40% acrylic resin emulsified in water as a ligament, activated carbon fiber of the Spanish company Carbongen, S .. A. (Alcoy, Alicante), of a specific surface area (S _BET ) of 1100 m ² / g, according to the BET equation applied to the isotherm of N ₂ at 77 ° K, finely ground;

- synthetic thickener: ethylene oxide;

- viscose fabric.

To obtain each 10Og of the coating, the thickener (1Og) was dissolved in water (20 ml).

On the other hand, water was added to the activated carbon fiber (80 g in 520 ml of water), and stirred until the fiber was well dispersed.

Once dispersed, the thickener was added and stirred until homogenized.

Finally, the ligament (200 ml) was added, stirred well until a uniform thick mass remained. This dough was ready to be applied as a coating.

The coating was applied on a cellulosic tissue to a homogeneously shaped face.

The coated fabric was dried at 120 ⁰ C, and then the resin is crosslinked (cured) at 150 ⁰ C for 5 minutes.

The final product was a 90- tissue contained 100 g of coating per m ^2. The activated carbon fiber used had a specific surface initial (BET) of 1100 m ² / g being that of the finished coating of 800, determined by the same method. Because the fiber represented 70-80% of the total final dry weight, the effect of the ligament and thickener on the adsorption capacity of the fiber is negligible, that is, the fiber continued to maintain its adsorption capacity.

Figure 1 is a photograph taken of this sample in which the original (white) and coated fabric (black upper part) can be observed.

Example 2: Activated carbon and acrylic resin adsorbent (4: 1). Applied on a fabric for possible application as an adsorbent or filter layer. It was used:

- a 40% acrylic resin emulsified in water as a ligament;

- powdered activated carbon (S _BET of 1000 m ² / g);

- semi-synthetic cellulosic base thickener; - viscose fabric

On the other hand, water was added to activated carbon

(80 g in 380 ml of water), and stirred until the fiber was well dispersed.

Once dispersed, the ligament (200 ml) was added, stirred well until a uniform thick mass remained. This sample was ready to be applied as a coating. The coating was applied on a cellulosic tissue to one face.

Cellulosic fabric coated at 120 ⁰ C dried and then the resin was crosslinked at 150 ⁰ C for 5 minutes. The product was washed in water to remove the thickener. The final product was a 90- tissue contained 100 g of coating per m ^2. The activated carbon used had an initial specific surface area (BET) of 1000 m ² / g being that of the finished coating of 700.

Example 3: Microporous carbon coating on carbon fabric for application as an electrode in fuel cells.

In this embodiment, the most important thing was to coat the fabric with a layer that had good electrical properties while having good adsorbent properties. Activated carbon fibers, along with carbon blacks, are the only materials that possess both properties. In addition, a barrier that is homogeneous and hydrophobic should be formed. It was used:

- as a ligament a 40% acrylic resin emulsified in water with the possibility of mixing it with a 60% fluorinated resin in water (in relation 2: 1 respectively);

- activated carbon fiber of Carbongen, S.A., and graphite powder.

- synthetic thickener: ethylene oxide

- 30% tefloned carbon fabric, 145 g / m ² surface density with good electrical properties

(conductivity of 6-10 Siemens / cm), by Carbongen, S. A.

To obtain every 10Og of the coating, the ligaments (50 ml) were dissolved in water (125 ml), stirred well until uniform. The carbon (50g) was added and stirring was continued until the dough was uniform.

Gradually, the thickener (26.125g) was added until a thick and uniform mass was obtained.

This sample was ready to be applied as a coating. The coating was applied on the crosslinked carbon fabric to one side.

The coated fabric was dried at 120 ⁰ C and then the resins were crosslinked at 150 ⁰ C for 5 minutes. The operation was repeated until the complete interwoven light coating.

The surface resistivity of the resulting product was measured (by the 4-pointed method) obtaining the following values: Original tefloned fabric: 6.7 Siemens / cm

Coated fabric: 6.3 Siemens / cm.

The electrical measurements were made by the 4-prong method with a current of 5 mA and 120x50 mm samples. Figures 2 and 3 are photographs of the sample prepared in this example, specifically Figure 2 is a photograph of the scanning electron microscope (SEM) where the distribution of a more or less homogeneous fiber layer is seen at 300 magnifications, and Figure 3 is a conventional photograph showing the difference in appearance between the original fabric (below) and the aspect that remains on the coated face (superimposed on the original fabric).

Example 4: Coating of activated carbon fiber and exchange resins on cellulosic tissue for water purification application.

In this embodiment, the most important thing was to obtain a product applicable to the field of water filtration that combines the ability to remove chlorine and organic compounds from water with the ability of exchange resins to retain calcium and other dissolved metals together with sulfate-type anions , chlorides, carbonates, etc. and get water of great purity. It was used:

- as ligament an acrylic resin emulsified in water. - activated carbon fiber of Carbongen, SA, and cationic and anionic intercamio resins "Amberlite IRN-150"

(from Rohm & Haas) in 1: 1 mass ratio.

- synthetic thickener: ethylene oxide - viscose fabric.

To obtain every 10Og of the coating, the ligaments (50 ml) were dissolved in water (125 ml), stirred well until uniform.

Coal (25g) and finely ground "amberlite" resin (25g) were added and stirring was continued until mass uniformity.

This sample was ready to be applied as a coating.

The coating was applied on the tissue to one face.

The coated fabric was dried at 110 ⁰ C and then the resins were crosslinked at 120 ⁰ C for 5 minutes. The operation was repeated until the complete interwoven light coating.

Example 5: Coating of granular activated carbon on support fabric that forms a filter plate for gas purification application.

In this embodiment, the most important thing was to obtain a product applicable to the field of gas filtration, which allowed a good flow passage without a significant pressure drop. It was used:

- as ligament an acrylic resin emulsified in water.

- Granular activated carbon.

- synthetic thickener: ethylene oxide

- viscose fabric as support. To obtain each 10Og of the coating, the ligaments (17 ml) were dissolved in water (40 ml), stirred well until uniform.

Gradually, the thickener (12g) was added until a thick and uniform mass was obtained.

Granular activated carbon (70 g) was added so that the mineral charge: other components ratio was approximately 1: 1.

This sample was ready to be applied as a coating.

The coating was applied to the fabric on one side, giving it a thickness of 10 mm, as can be seen in Figure 5.

The coated fabric was dried at 110 ⁰ C and then the resins were crosslinked at 150 ⁰ C for

30 minutes. A rigid and consistent material of agglomeration of granular activated carbon was obtained, very suitable for gas filtration.

Claims

1. Adsorbent coating characterized in that it comprises

- a mineral load, in a percentage by weight, dry, of the final product between 10-90%, a water-based resin, which will act as a binder, in a percentage by weight, dry of the final product between 10-90% , a thickener, in a percentage by weight, dry, of the final product between 0.1-25%, water.

2. Coating according to claim 1, characterized in that the mineral charge is selected from activated carbons, activated carbon fibers, carbon black, graphites, zeolites, clays, amorphous silices, amorphous aluminas, amorphous metal oxides, ion exchange resins, and combinations thereof.

3. Coating according to claim 1, characterized in that the resin is at least one resin selected from acrylic resins, polyolefin resins, epoxy resins and fluorocarbon resins.

4. Coating according to claim 1, characterized in that the thickener is at least one thickener selected from natural thickeners, cellulose derivatives, petroleum proteins and synthetics.

5. Coating according to claim 1, characterized in that it comprises 50 to 90% by weight based on the total dry weight of the final mineral loading product.

6. Coating according to claim 1, characterized in that it comprises 60 to 80% by weight based on the total dry weight of the final mineral loading product.

7. Coating according to claim 1, characterized in that it comprises from 10 to 25%, by weight based on the total dry weight of the final product, of water-based resin.

8. Coating according to claim 1, characterized in that it comprises 5 to 15%, by weight based on the total dry weight of the final product, of thickener.

9. Coating according to claim 1, characterized in that it comprises

- 60 to 80%, by weight, based on the total dry weight of the final mineral loading product,

- 10 to 25%, by weight based on the total dry weight of the final product, of water-based resin;

10. Coating according to claim 1, characterized in that it comprises

- 10 to 25%, by weight, based on the total dry weight of the final product, of selected water-based resin between acrylic resins, polyolefin resins, epoxy resins and fluorocarbon resins;

11. Coating according to claim 1, characterized in that it comprises at least:

- 60 to 80%, by weight based on the total dry weight of activated carbon fiber,

- 5 to 15%, by weight based on the total dry weight of the final product, of ethylene oxide as a thickener.

12. Coating according to claim 1, characterized in that it comprises at least:

- 60 to 80%, by weight based on the total dry weight of activated carbon,

- 10 to 25%, by weight based on the total dry weight of the final product, of acrylic resin; - 5 to 15%, by weight, based on the total dry weight of the final product, of a semi-synthetic thickener with a cellulosic base.

13. Coating according to claim 1, characterized in that it comprises at least:

- 10 to 25%, by weight based on the total dry weight of the final product, of acrylic resin; - 5 to 15%, by weight based on the total dry weight of the final product, of ethylene oxide as a thickener.

14. Use of the coating defined in any one of claims 1 to 13 for the manufacture of a product selected from a product with the ability to absorb odors, a product with unsightly properties and a product with the ability to absorb odors and with anti-static properties.

15. Use of the coating according to claim 14, characterized in that said product capable of absorbing odors is selected from a fabric, a non-woven fabric, a wall surface, a wooden surface, a storage object.

16. Use of the coating according to claim 14 characterized in that said product with unsightly properties is a fabric, a wall or a floor.