Ironing system with steam promoter coating

Abstract

The invention relates to an ironing system comprising a steam generating device comprising a steam chamber provided with a coating (11) comprising a coating base material (15) with metal particles (25) at least partly embedded in the coating base material (15), wherein the coating base material (15) comprises a mixed metal silicate compound, wherein the mixed metal silicate compound comprises an alkali metal element and a first metal element, wherein the metal particles (25) comprise a second metal element, and wherein the first metal element and the second metal element are the same chemical element of the periodic table of the elements.

Claims

1. An ironing system comprising a steam generating device comprising a steam chamber provided with a coating comprising a coating base material with metal particles at least partly embedded in the coating base material, wherein the coating base material comprises a mixed metal silicate compound, wherein the mixed metal silicate compound comprises an alkali metal element and a first metal element, wherein the metal particles comprise particles of a second metal element, and wherein the first metal element and the second metal element are the same chemical element of the periodic table of the elements.

2. The ironing system according to claim 1, wherein the second metal element is selected from a group consisting of calcium, magnesium, zinc, and aluminum.

3. The ironing system according to claim 1, wherein the mixed metal silicate compound comprises one or more alkali metal elements selected from a group consisting of lithium, sodium, and potassium.

4. The ironing system according to claim 1, wherein the metal particles have a weight averaged mean diameter selected from a range of 0.1 to 5 μm.

5. The ironing system according to claim 1, wherein the coating further comprises silica particles.

6. The ironing system according to claim 1, wherein the coating further comprises glass flakes.

7. The ironing system according to claim 1, wherein at least 99% of a weight of the metal particles consists of the second metal element, and wherein the coating comprises a mean thickness selected from a range of 30 to 120 μm.

8. The ironing system according to claim 1, wherein the ironing system is a steam iron.

9. The ironing system according to claim 1, wherein the second metal element comprises a metal element having a valence higher than 1.

10. The ironing system according to claim 1, wherein a ratio of a weight of the metal particles to a weight of alkali metal silicate, comprised in the mixed metal silicate compound, is selected from a range of 0.001:1 to 3:1.

11. The ironing system according to claim 5, wherein the silica particles have a weight averaged diameter selected from a range of 0.1 to 1000 nm.

12. The ironing system according to claim 1, wherein the second metal element is selected from a group consisting of gallium, indium, copper, and nickel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

(2) FIG. 1 schematically depicts an embodiment of an ironing system according to the invention;

(3) FIG. 2 schematically depicts aspects of the coating according to the invention;

(4) FIG. 3 schematically depicts some aspects of the method of producing a coating at a surface a coating to the invention;

(5) FIG. 4A-4B depicts some embodiments of an ironing system according to the invention.

(6) The schematic drawings are not necessarily on scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(7) FIG. 1 schematically depicts an embodiment of an ironing system 1000 comprising a steam generating device 100. Especially, the depicted embodiment is a steam iron 1001. The steam iron 1001 comprises a housing 1 which is closed on the bottom side by an aluminum soleplate 2, which is provided with a thin layer of stainless steel on the underside 3. The soleplate 2 is provided with upright ribs 4 on the inside, on which ribs 4 an aluminum plate 5 is provided in such a manner that a steam chamber 6 is formed between the inside of the soleplate 2 and the plate 5. The steam chamber 6 is sealed by an elastic silicone rubber 7. The steam iron 1001 further comprises a water reservoir 8. By means of a pumping mechanism 9, water from the reservoir 8 can be sprayed directly onto the clothes to be ironed. By means of a pumping mechanism 10, water can be pumped from the reservoir 8 into the steam chamber 5, thus increasing the steam output. This water passes through an aperture (not shown) in plate 5 to the bottom of the steam chamber 6. The bottom of the steam chamber 6 comprises a surface 112, especially a steam chamber surface 12 that is provided with a coating 11, according to the invention, having a thickness 13. In embodiments, this thickness 13 is especially in the range of 30 to 120 μm. The steam generating device 100 depicted in FIG. 1 comprises a steam chamber 6 provided with a coating 11 according to the invention. Aspects of this coating 11 are amongst others depicted in FIG. 2.

(8) In FIG. 2, a part of an embodiment of a coating 11 having a mean thickness 13 is schematically depicted, comprising a coating base material 15 with metal particles 25 embedded in the coating base material 15. In the depicted embodiment, the coating 11 further comprises a filler (filler material), especially silica particles 30, such as precipitated colloidal silica and glass flakes 31. In further embodiments, (other) silica particles may comprise different dimensions and shapes. In the schematically depicted coating 11, (only) a small amount of filler material is depicted. In embodiments, the amount of filler may be selected from the range of 50 to 70 wt. % of the (dried) coating.

(9) The coating base material 15 comprises a mixed metal silicate compound. Especially such mixed metal compound comprises alkali metal elements and first metal elements. The metal particles 25 are at least partly embedded in the coating base 15 and comprise a second metal element. These metal particles 25 may especially have a weight averaged mean diameter 26 selected from the range of 0.1 to 5 μm. Substantially the entire metal particle is metal. Hence, especially at least 99% of a weight of the metal particles 25 may consists of the second metal element.

(10) The invention is especially based on strengthening an alkali metal silicate by a metal to provide a mixed metal silicate (or an alkali metal/metal silicate). The improved characteristics of the alkali metal (/metal) silicate may be the result of a metal that may react with the alkali metal silicate, resulting an alkali metal/metal silicate compound with increased strength. The metal may dissolve in the alkali metal silicate because of the caustic environment (of the alkali metal silicate). Essentially, the first metal element and the second metal element relate to the same metal and therefore are essentially the same chemical element of the periodic table of the elements. In embodiments, the second metal element is selected from the group consisting of calcium, magnesium, zinc, and aluminum. In further embodiments the mixed metal silicate compound comprises one or more alkali metal elements selected from the group consisting of lithium, sodium, and potassium.

(11) The coating 11 may be provided by the method of producing a coating 11 at a surface 112, as described herein, see FIG. 3, depicting successive stages of the method). In such method, a mixture 50 comprising an alkali metal silicate 140 and metal particles 25 and optionally silicate particles 30 are prepared (depicted at the top of FIG. 3), provided to the surface 112, e.g. by spraying (middle two pictures in the scheme) and successively the mixture 50 is cured at (an) elevated temperature to form the coating 11 (shown at the bottom of the figure). Especially, curing may be provided at an elevated temperature in the range of 200 to 500° C. In embodiments of the method the weight averaged mean diameter 26 of the particles 25 is selected from the range of 2 to 6 μm to provide a mixture that especially may be sprayable and may provide the desired insolubility of the final coating 11 after drying (curing). Especially, the mixture or coating composition 60 is a liquid (flowable) composition. If the method is applied for a steam generating device 100, the surface 112 may especially comprise a steam chamber surface 12 for a steam chamber 6. In such embodiment, curing the mixture 50 at elevated temperature may advantageously comprise heating the steam chamber surface 12. Especially, the mixture 50 may be sprayed in the steam chamber 6 before installing the aluminum plate 5 (see FIG. 1).

(12) In an embodiment, lithium silicate is mixed with zinc powder and sprayed at the steam chamber surface 12. After heating the steam chamber 6 to 300° C. strong zinc silicate bonds are formed with intrinsically higher strength than the native alkali silicate that is reacted silica. In another embodiment, potassium silicate is mixed with aluminum powder. After curing at 300° C. strong aluminum silicate bonds are formed with intrinsically higher strength than the native alkali silicate that is reacted with silica. Especially, the solubility of the formed mixed metal silicates is low, preventing any dissolution upon usage which may especially be advantageous for the application.

(13) The mixture or coating composition 60 at least comprises an alkali metal silicate compound and metal particles 25, especially having a weight averaged mean diameter 26 of the particles 25 between 2 and 6 μm. To provide the desired coating 11, the metal particles 25 may in embodiments comprise a second metal element selected from the group consisting of calcium, magnesium, zinc, and aluminum.

(14) In FIG. 4A-4B some embodiments of an ironing system 1000 according to the invention are depicted. The ironing system 1000 comprise steam generating device 100 described herein. In FIG. 4A an integrated steam iron 1001 is depicted comprising a steam generation device 100, a water reservoir 8 and an ironing device in an integrated device. In FIG. 4B a system iron 1002 is depicted comprising a steam iron 1001 connected to a steam generating 100 with a water reservoir 8 via a steam transport hose 40.

(15) Chemicals

(16) Lithium silicate (LiSi) (20% in water), Ludox As40, and Zinc powder (2-5 μm) were obtained from Sigma Aldrich; Potassium silicate (Kasolv 205) was obtained from PQ Corporation; Aerosil OX50 silica powder was obtained from Evonik; Glass flakes (GF001) were obtained from Glass Flake Ltd; Aluminum powders were obtained from Eckart; examples of the applied Aluminum powders are WA23 (spheres with mean size 2.3 μm), WA55 (spheres with mean diameter 5.5 μm), PCR 1100 (flakes with mean diameter 8 μm), RO550 (flakes with mean diameter of 20 μm).

(17) Lacquer Preparation

(18) A typical lacquer preparation was as follows:

(19) Potassium silicate based: 5 g. WA23 aluminum powder was mixed with 3 g. water and stirred until the powder had dispersed into a paste. To the paste a solution of 8.4 g. Kasolv 205 in 30 g. As40 (40% colloidal silica in water) was added followed by 9 g. GF001 glass flakes. Additionally 2.5 g. Aerosil OX50 fumed silica powder was added. The high viscous material can be diluted with additional DI water to obtain the proper viscosity for spraying

(20) Lithium silicate based: 2grWA23 was dispersed in 31 g. Lithium silicate solution. 9 g. GF001 glass flakes were added followed by 10 g. OX50 silica powder. Additional water can be added for sprayability.

(21) Application and Drying

(22) Steam promoter formulations (lacquers) were sprayed into the steam chamber of a soleplate of a steam iron. After spraying the heating element that was embedded in the soleplate was used to heat the soleplate and dry the coating. Heating was continued till the soleplate reached 300° C.

(23) Resistance to DI Water

(24) In a typical experiment an open soleplate with a steam promoter layer applied in the steam chamber was heated to 240° C. DI (DeIonized) water was continuously dripped onto the layer and transformed into steam. After 10 l. of water the layer was inspected for color deviations and change in structural appearance. The impact of Aluminum and Zinc powder on the resistance of alkali silicate towards DI water was evaluated in the following experiments.

(25) Aluminum Potassium Silicate

(26) WA23 aluminum powder was mixed with 3 g. water and stirred until the powder had dispersed into a paste. To the paste a solution of 8.4 g. Kasolv 205 in 45 g. As40 was added followed by 9 g. GF001 glass flakes. The high viscous material can be diluted with additional DI water to obtain the proper viscosity for spraying. The amount of WA23 aluminum powder used in the series of experiments was chosen from 0, 1, 2 and 5 gr.

(27) Testing according the description showed the sample without any aluminum powder having turned white with a powdery appearance. The sample with 1 g. powder had improved significantly with less whitening and color change. The 2 g. sample had improved even more while the sample with 5 g. WA23 powder showed no appearance deviation from the original grey color.

(28) Zinc Potassium Silicate

(29) Similar experiments were done by using Zinc powder where 1 gram Zinc powder showed whitening of the layer but 5 g. and 10 g. Zn powder showed no change upon testing with DI water.

(30) Zinc Lithium Silicate

(31) 31 g. Lithium silicate solution was mixed with 9 g. GF001 and 10 g. Ox50 silica. The layer based on this material was turning white upon testing with DI water. Mixing 31 g. Lithium silicate solution with 9 g. GF001 and 18 g. Zinc powder gave a layer that did not change color or appearance upon dosing DI water at 240 C.

(32) Aluminum Potassium Silicate

(33) 8.4 g. Kasolv 205 in 20 g. water was mixed with 9 g. GF001 glass flakes and 5 g. WA23 aluminum powder.

(34) The layer made from this was resistant to DI water at 240° C. contrary to the aluminum free material.

(35) Metal Powder Vs Soluble Metal Salts

(36) Using metal powder contrary to soluble metal salts may be advantageous effect, especially because adding non-alkali metals in the form of a soluble metal salt may lead immediately to gel formation as the reaction of the silicate with the metal ions may lead to insoluble structures and hence gel particles or full gelation upon mixing. The high reactivity of metal salts towards alkali silicate solutions is experimentally studied. In a typical experiment 0.5 g. Al(NO.sub.3).sub.3 was dissolved in a small amount of water and added to 30 g. Lithium silicate solution. Immediate gelation took place. The same happened when e.g. CaCl.sub.2) or Zn(Acetate).sub.2 solutions were added in the same way.

(37) Gel formation also happened when using a Potassium Silicate solution (8.4 g. Kasolv 205 in 20 g. water) and adding the solutions of the salts mentioned above.

(38) The immediate reaction of the metal ions with the silicate leads to full gelation or formation of gel particles giving rise to inhomogeneous materials that are difficult to spray.

(39) The metal powders can be easily dispersed into the silicates and their reactivity at room temperature is low enough to avoid premature gelation and therefore allow for sufficient pot life to make them usable in a production environment. Upon heating/curing the metal powders will (partly) dissolve and form the corresponding metal silicate strengthening the material to avoid any dissolution in water.

(40) As the reaction with the metal powder is heterogeneous a high surface area metal powder (small particle size) is especially preferred. This is to ensure that sufficient metal ions coming from the powder will migrate into the silicate matrix.

(41) Resistance to Scale Flaking

(42) In a typical experiment an open soleplate with steam promoter layer applied in the steam chamber was heated to 240° C. Hard water was continuously dripped onto the layer and transformed into steam.

(43) After a few h. steaming a layer of scale had formed on top of the steam promoter. The heating and dripping was stopped. Cooling was done by slowly leaving in ambient or enforced by adding copious amount of cold water hence generating high stresses in the layer.

(44) The scale (when sufficiently thick) was flaking from the steam promoter due to internal stress build up. Resistance of the steam promoter layer to the flaking of the scale was checked by subsequently reheating again to 240° C. and checking for steaming performance. A properly designed steam promoter layer was able to show good steaming and no Leidenfrost effect after flaking of the scale and be able to withstand at least 7 cycles of steaming/scale formation/flaking. When a steam promoter has insufficient strength, the flaking will be in the steam promoter layer itself or at the interface of the steam promoter to the aluminum base and not at the interface of coating and scale. Upon flaking the scale will remove part of the steam promoter leading to Leidenfrost effect.

(45) Different types of water were used in the testing.

(46) The first hard water was based on an IEC standard and is made in the following way: Stock solutions of CaCl.sub.2.2H.sub.2O (65.6 gr/l), MgSO.sub.4.7H.sub.2O (38 gr/l.) and NaHCO.sub.3 (76.2 gr/l.) were made. This standard hard water was made by mixing 50 gram of each stock solution into 9 liter of de-ionized water and adding up to 10 liter. The resulting water had a total hardness of 16.8° DH and a temporary hardness of 11.2° DH. Total hardness is defined as 2.8×2×[mmol Ca.sup.2+/l.+mmol Mg.sup.2+/l.]. Temporary hardness is defined as 2.8×[mmol HCO.sub.3.sup.−/l.].

(47) A second type of water was from natural source with both total and temporary hardness of 14° DH.

(48) The type of scale was different from both waters. The scale form the IEC water was more soft and fluffy in nature while the scale from the natural water was typically hard and dense.

(49) An embodiment of a steam promoter that showed resistance towards scale flaking is based on the following lacquer:5 g. WA23 aluminum powder, 8.4 g. Kasolv 205, 30 g. As40, 9 g. GF001 glass flakes and 2.5 g. Aerosil OX50 fumed silica powder.

(50) When low amount aluminum powder is used not only DI water resistance is compromised but also strength. For example a layer based on 8.4KSi/10OX50/9E/1WA23 shows insufficient strength to survive scale flaking.

(51) A steam promoter based on a silicate with comparably large aluminum flakes like e.g. PCR 801 (particles with a mean of 14-20 micron but with particles up to 40 micron) will be too low in strength/adhesion to survive flaking.

(52) For example a steam promoter based on 31.6 g. LiSi, 9 g. GF001 and 5 g. or 18 g. PCR801 will show strong Leidenfrost effect after the scale flaking. The scale had almost completely removed the layer from the soleplate.

(53) Fillers

(54) The choice of fillers also determines strength. Silica based fillers are especially preferred over alternative fillers. Silica interferes directly with alkali silicate and helps in strengthening the final material.

(55) Metal silicates are not reacting with the alkali silicate in the way silica can do which is reflected directly in flaking resistance

(56) For example a layer based on LiSi, WA23 and GF001 flakes is used as starting material. Filing this starting formulation with As40 silica may give a flaking resistant layer. Filling with CaCO.sub.3 or Talcum (Mg.sub.3Si.sub.4O.sub.10(OH).sub.2) or Mica (mixed metal silicate containing e.g. Ca, Mg and Al) or CaSiO.sub.3 especially may not.

(57) Besides the benefit of silica filling over other fillers it also shows again the importance of the metal powder filling.

(58) Metal ions introduced in the form of a soluble salt especially have shown to be too reactive causing gelation as mentioned above. Metal ions bonded into silicates, carbonates etc. are low reactive and give a low strengthening effect. The metals are already bonded in a non-soluble crystal structure and not available for reacting with the alkali silicate. Metal ions coming from metal powder may especially be a good way to balance reactivity and ease of use in alkali silicate based steam promoter.

(59) Experimentally, also metal ions bonded to hydroxide did not show a beneficial effect to the strength of the layer. For example a coating layer based on the potassium silicate composition as described in the lacquer preparation part was used but the aluminum powder was replaced with 2.5 gr. AlOH.sub.3 or 5 gr. AlOH.sub.3. In both cases no viscosity increase occurred. After application, the layer was subjected to the DI water test showing compromised strength and especially adhesion problems to the aluminum soleplate.

(60) The term “substantially” herein, such as in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”. The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

(61) Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

(62) The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

(63) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

(64) The invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

(65) The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.