Water-absorbent conductive compositions and their use as sensors for monitoring erosion and / or corrosion - Patents.com

Abstract

The present invention relates to a water-absorbing, conductive composition comprising: a) a water-soluble and / or water-swellable and / or water-absorbent resin; b) a conductive filler; and c) a solvent. The water-absorbing, conductive composition according to the present invention can be used as a sensor for erosion and / or corrosion monitoring.

Description

[Technical field]

[0001] The present invention relates to a water-absorbing, electrically conductive composition comprising a water-soluble and / or water-swellable and / or water-absorbent resin, and the use of said composition as a sensor for monitoring erosion and / or corrosion. [Background technology]

[0002] Protective coatings are used to protect plant assets such as pumps, heat exchangers, storage tanks, pipes, chutes, etc. from harsh environments such as chemicals, abrasion, and environmental corrosion. Although protective coatings can extend the life of an asset by several years, over time, continuous operation under harsh working conditions (temperature, humidity, chemical etching, and abrasion) can begin to crack, erode, and delaminate from the parent substrate, reducing performance. When the coating begins to peel off, the parent substrate is directly exposed to the harsh working environment and becomes vulnerable. The substrate begins to corrode and / or erode and loses wall thickness, which can lead to equipment failures that reduce the asset's operational efficiency or cause unplanned downtime. Unplanned downtime leads to lost productivity. Delayed equipment repairs increase the risk of sudden failures and also jeopardize worker safety.

[0003] In some cases, coating erosion is visible and easy to detect, but not always. Furthermore, detection depends on where the coating material is used and may not be detectable by visual inspection. Operating conditions such as flow rate, temperature, and pressure to increase productivity and efficiency are monitored on equipment in many process industries. However, it is not possible to continuously monitor coatings inside tanks, pipes, propellers, etc., and the behavior and timing of coating erosion and / or corrosion is unknown. Current methods are based on the experience and historical data of plant managers, but not on predictive maintenance. According to current practice, in many industries, the condition of assets is monitored during annual plant shutdowns, at which point some assets are already damaged and require costly replacement. This could be avoided if predictive maintenance was implemented. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, there is a need to develop sensing materials to sense and monitor the performance of coatings so that failures can be prevented by early detection and appropriate and timely measurements to extend asset life while maintaining high productivity. [Means for solving the problem]

[0005] Summary of the Invention The present invention relates to a water-absorbing, conductive composition comprising: a) a water-soluble and / or water-swellable and / or water-absorbent resin; b) a conductive filler; and c) a solvent.

[0006] The present invention also relates to a cured product of the water-absorbing, electrically conductive composition according to the present invention.

[0007] The present invention includes the use of a water-absorbing, conductive composition or cured product according to the present invention as a sensor for monitoring erosion and / or corrosion. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 shows a substrate and a coated substrate (FIGS. 1a and 1b). [Diagram 2] FIG. 2 shows the test substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Detailed Description of the Invention In the following passages the invention will be described in more detail. Each aspect so described may be combined with any other aspect, unless expressly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

[0010] In the context of the present invention, the terms used are to be construed in accordance with the following definitions, unless the context dictates otherwise.

[0011] As used herein, the singular forms "a," "an," and "the" include both singular and plural referents unless the context clearly dictates otherwise.

[0012] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," or "containing," and are inclusive or open-ended and do not exclude additional, non-limiting members, elements, or method steps.

[0013] As used herein, the term "consisting of" excludes unspecified elements, components, members, or method steps.

[0014] The recitations of numerical endpoints include all values ​​and fractions subsumed within the respective ranges as well as the recited endpoints.

[0015] All percentages, parts, ratios, etc. referred to herein are by weight unless otherwise indicated.

[0016] When an amount, concentration, or other value or parameter is expressed in the form of a range, a preferred range, or an upper preferred value and a lower preferred value, it is to be understood that any range obtained by combining any upper or preferred value with any lower limit or preferred value is specifically disclosed, regardless of whether the resulting range is expressly stated in the context.

[0017] All references cited herein are incorporated by reference in their entirety.

[0018] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs. As a further guide, definitions of terms are included to better understand the teachings of the present invention.

[0019] The present invention relates to a water-absorbing, electrically conductive composition comprising a water-soluble and / or water-swellable and / or water-absorbent resin. The water-absorbing, electrically conductive composition according to the present invention can be used as a sensor for monitoring erosion and / or corrosion.

[0020] Applicants have discovered that water-absorbing, conductive coating compositions can be used as sensors to monitor the erosion of coatings (protective top layers applied to the surface of a substrate).

[0021] The present invention relates to a water-absorbing, conductive composition comprising: a) a water-soluble and / or water-swellable and / or water-absorbent resin; b) a conductive filler; and c) a solvent.

[0022] The water-absorbing conductive composition according to the present invention comprises a water-soluble and / or water-swellable and / or water-absorbent resin. The water-soluble and / or water-swellable and / or water-absorbent resin can be any resin that is water-soluble, swells in the presence of water or absorbs water. Preferably, said water-soluble and / or water-swellable and / or water-absorbent resin is selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), cellulose ethers, methylcellulose, hydroxylpropylcellulose, gum arabic, starch (dextrin), casein (phosphoprotein) and mixtures thereof, more preferably selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), methylcellulose and mixtures thereof.

[0023] Sodium polyacrylate, polyvinylpyrrolidone (PVP) and methylcellulose are preferred due to their excellent water solubility.

[0024] Commercially available water-soluble and / or water-swellable and / or water-absorbent resins suitable for use in the present invention include, but are not limited to, sodium polyacrylate from Prime Specialities, India; polyvinylpyrrolidone (PVP) from Ashland Specialty Industries; and methylcellulose from DOW Chemical Company.

[0025] The water-soluble and / or water-swellable and / or water-absorbent resin may be present in the water-absorbent conductive composition according to the present invention in an amount of 5 to 30% by weight, preferably 7.5 to 25% by weight, more preferably 8 to 22% by weight of the total weight of the composition.

[0026] Applicant has found that these amounts are preferred because amounts greater than 30% may cause stability issues during application. Amounts less than 5% may not provide the desired water detection effect. Furthermore, it has been found that a range of 5-30% of water-soluble and / or water-swellable and / or water-absorbent resin is optimal to provide a better response as a sensor.

[0027] The water-absorbing conductive composition according to the present invention contains a conductive filler. In theory, any conductive filler may be used. Preferably, the conductive filler is selected from the group consisting of carbon, carbon black, carbon nanotubes, graphite, graphene, silver, nickel, copper, gold, platinum, aluminum, iron, zinc, cobalt, lead, tin alloy, silver-coated copper, silver-coated graphite, silver-coated polymer, silver-coated aluminum, silver-coated glass, silver-coated carbon, silver-coated boron nitride, silver-coated aluminum oxide, silver-coated aluminum hydroxide and mixtures thereof, more preferably, the conductive filler is selected from the group consisting of carbon black, carbon nanotubes, graphite and mixtures thereof.

[0028] In one embodiment, the conductive filler is carbon black.

[0029] In one embodiment, the conductive filler is carbon nanotubes.

[0030] In one embodiment, the conductive filler is graphite.

[0031] In yet another embodiment, the conductive filler is a mixture of carbon black and graphite.

[0032] In yet another embodiment, the conductive filler is a mixture of carbon black, graphite, and carbon nanotubes.

[0033] Commercially available conductive fillers suitable for use in the present invention include, but are not limited to, Timrex SGF 15 from Imerys Graphite & Carbon, Vulcan PF from Cabot Corporation, and Vulcan XC 72 from Cabot Corporation.

[0034] The conductive filler may be present in the water-absorbing conductive composition according to the present invention in an amount of 10 to 35% by weight, preferably 12 to 33% by weight, more preferably 15 to 30% by weight of the total weight of the composition.

[0035] Applicants have discovered that these amounts are preferred because amounts greater than 35% may cause rheological problems during application and amounts less than 10% may not provide the desired conductivity.

[0036] If the conductive filler is carbon black, carbon nanotubes, or graphite, the amount may also depend on the oil absorption of the filler. The oil absorption varies for carbon black, carbon nanotubes, and graphite and depends on the particle size and specific surface area of ​​the conductive filler. For example, carbon nanotubes have a high oil absorption due to their small particle size (nanoscale). As a general guideline, the higher the oil absorption, the less particles are required. Oil absorption is measured according to ASTM-D281.

[0037] The water-absorbing conductive composition according to the present invention comprises a solvent. Solvents suitable for use in the present invention have a boiling point below 235° C. Preferably, the solvent is selected from the group consisting of n-butanol, butyl carbitol, 1-methoxy-2-propanol acetate, isopropyl alcohol, butyl cellosolve and mixtures thereof, more preferably, n-butanol, butyl carbitol, 1-methoxy-2-propanol acetate and mixtures thereof.

[0038] The preferred solvents, n-butanol, butyl carbitol, and 1-methoxy-2-propanol acetate, are polar solvents, which are desirable because they act during processing of the composition. Additionally, these preferred solvents also act as coalescing agents in the composition.

[0039] Commercially available solvents suitable for use in the present invention include, but are not limited to, n-butanol from Sigma Aldrich.

[0040] The solvent may be present in the water-absorbing conductive composition according to the present invention in an amount of 10 to 70% by weight, preferably 20 to 65% by weight, more preferably 30 to 60% by weight of the total weight of the composition.

[0041] This solvent amount range is preferred as it provides good applicability (composition) on the substrate.

[0042] The water-absorbing conductive composition according to the present invention may further comprise a resin. The resin suitable for use in the present invention is preferably a thermoplastic resin. The thermoplastic resin-based composition causes the water-absorbing polymer to absorb water and change the electrical resistance of the composition.

[0043] In a highly preferred embodiment, the water-absorbing, conductive composition according to the present invention comprises a resin.

[0044] Preferably, the resin is selected from the group consisting of vinyl resins, copolymers of vinyl chloride and vinyl acetate, thermoplastic polyurethane resins, polyvinyl butyral resins, (meth)acrylate resins, phenoxy resins, epoxy resins, polyester resins, and mixtures thereof, more preferably the resin is selected from the group consisting of copolymers of vinyl chloride and vinyl acetate, polyvinyl alcohol resins, polyvinyl butyral resins, and mixtures thereof.

[0045] Copolymers of vinyl chloride and vinyl acetate, polyvinyl alcohol resins and polyvinyl butyral resins are preferred resins because they are non-oxidizing and permanently flexible while providing the desired toughness and durability. In addition, they are characterized by the absence of color, odor and taste. Dilute alkali, mineral acids, alcohols, greases, oils and aliphatic hydrocarbons cannot adversely affect the polymers at room or ambient temperatures.

[0046] Commercially available resins suitable for use in the present invention include, but are not limited to, UCAR Vagh manufactured by Dow Chemical Company.

[0047] The resin may be present in the water-absorbing conductive composition according to the present invention in an amount of 5 to 25% by weight, preferably 7.5 to 20% by weight, more preferably 9 to 15% by weight of the total weight of the composition.

[0048] The applicant has found that these amounts are preferred, since amounts greater than 25% may lead to a decrease in electrical conductivity. Moreover, too high an amount may cause rheological problems during application. On the other hand, amounts less than 5% may not provide the desired adhesion to the substrate and / or base layer (coat) and / or top layer (coat).

[0049] The water-absorbing conductive composition according to the present invention may further comprise an antifoaming agent. During the preparation of the composition according to the present invention, an antifoaming agent may be added to the composition to reduce foaming during the dispersion process.

[0050] Any commercially available defoamer may be used in the compositions according to the present invention. Suitable defoamers for use in the present invention are, for example, silicone-free polymeric air release agents.

[0051] Commercially available defoamers suitable for use in the present invention include, but are not limited to, BYK-A 505 manufactured by BYK.

[0052] The defoamer may be present in the water-absorbing conductive composition according to the present invention in an amount of 0.1 to 1% by weight, preferably 0.1 to 0.7% by weight, more preferably 0.1 to 0.5% by weight of the total weight of the composition.

[0053] Applicants have discovered that these amounts are preferred because amounts greater than 1% can adversely affect coating performance such as surface wetting, while amounts less than 0.1% may not provide the desired antifoaming effect.

[0054] The present invention also relates to a cured product of the water-absorbing, electrically conductive composition according to the present invention.

[0055] The present invention relates to the use of the water-absorbing, electrically conductive composition according to the present invention or the cured product according to the present invention as a coating material.

[0056] The present invention encompasses the use of the water-absorbing, electrically conductive composition according to the invention or the cured product according to the invention as a sensor for monitoring erosion and / or corrosion.

[0057] The sensor for monitoring erosion and / or corrosion according to the present invention can be used, for example, in applications where predictive monitoring helps to extend asset life. The sensor for monitoring erosion and / or corrosion according to the present invention can be beneficial, for example, in slurry pumps in steel mills, power plants and mining. These slurry pumps are widely used to transport wet ore slurries to various components for processing. These are critical assets that are exposed to severe erosive and corrosive environments and require frequent replacement etc. EXAMPLES

[0058] Unless otherwise stated, all weights are in weight percent.

[0059] Samples for electrical resistance measurement were prepared as follows.

[0060] A composite test vehicle (125 x 12.7 x 3 mm) (Figure 1) was fitted with 50 μm thick copper leads for wire connection. These copper leads were used to hang wires for measuring the resistance of the coated specimens. A composition according to the invention was applied onto the specimens, which were subsequently cured at room temperature for 24 hours and post-cured at 100°C for 30 minutes. The electrical resistance was measured according to ASTM D2739-97.

[0061] The water drop test was carried out as follows: For the test, a panel was coated with a conductive composition according to the present invention. The composition was applied to the surface of the substrate and dried in an oven at 100°C for 30 minutes. Figure 1 shows the substrate and the coated substrate (Figures 1a and 1b). The water drop test was carried out by adding 2-3 drops of water to the center of the coated substrate. The electrical resistance was measured before and after adding the water drops. The electrical resistance of the substrate was measured using a Keysight DAQ970 A - Data Acquisition System. The test substrate is shown in Figure 2.

[0062] The following chemicals are used in the examples: Timrex SGF 15 made by Imerys Graphite & Carbon Vulcan PF and Vulcan XC 72 from Cabot Corporation Arcosolv PM Acetate from Lyondell Chemical Company Butyl Carbitol manufactured by Dow Chemical Company UCAR Wagh manufactured by Dow Chemical Company Polyvinylpyrrolidone (PVP) from Ashland Specialities Ingredients Methylcellulose from DOW Chemical Company n-Butanol from Sigma Aldrich Sodium Polyacrylate from Prime Specialities, India

[0063] Example 1 Table 1 below illustrates the presence of sodium polyacrylate as a water-absorbing polymer (Example 1) and a composition without it (Comparative Example 1a): The compositions were prepared in a high-speed mixer at 2000 rpm for 30 minutes.

[0064] [Table 1]

[0065] Substrates were coated with the compositions of Examples 1 and 1a and used to perform water drop tests. The coated substrates are shown in Figure 1. A test vehicle (shown in Figure 2) was used to measure electrical resistance with and without exposure to water. The results of the water drop test are shown in Table 2 below. Example 1 showed good response to water, with electrical resistance increasing by 62.92% in 30 minutes, while Comparative Example 1a showed no change in electrical resistance after 5 minutes.

[0066] [Table 2]

[0067] Example 2 Compositions containing water-absorbing polymers based on PVP or Methocel VLV in a thermoplastic binder are shown below in Table 3. Compositions containing 10% and 20% PVP and Methucel VLV were prepared in a high speed mixer at 2000 rpm for 30 minutes.

[0068] [Table 3]

[0069] A layer of the conductive coating composition was applied onto the substrate and kept in an oven at 100° C. for 30 minutes. The coated substrate is shown in FIG. 1. A test vehicle (shown in FIG. 2) was used to measure electrical resistance with and without exposure to water. The compositions containing 10 and 20% PVP (Examples 3 and 4) exemplified electrical resistance changes of 381% and 528%, respectively, in 10 minutes. Additionally, the compositions containing 10 and 20% Methocel VLV (Examples 5 and 6) exemplified electrical resistance changes of 25.86% and 133%, respectively, in 10 minutes. The PVP-based coating composition using PVP as the only binder (Example 2) exemplified electrical resistance changes of 27054% in 10 minutes. The results are shown in Table 4.

[0070] [Table 4]

Claims

1. a) A water-soluble and / or water-swellable and / or water-absorbent resin; b) A conductive filler; and c) A solvent A water-absorbent and conductive composition comprising the same.

2. The water-soluble and / or water-swellable and / or water-absorbent resin is selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), cellulose ether, methylcellulose, hydroxypropylcellulose, gum arabic, starch (dextrin), casein (phosphoprotein), and mixtures thereof, more preferably selected from the group consisting of sodium polyacrylate, polyvinylpyrrolidone (PVP), methylcellulose, and mixtures thereof. The water-absorbent and conductive composition according to Claim 1.

3. The water-soluble and / or water-swellable and / or water-absorbent resin is present in an amount of 5 to 30% by weight, preferably 7.5 to 25% by weight, more preferably 8 to 22% by weight, based on the total weight of the composition. The water-absorbent and conductive composition according to Claim 1.

4. The conductive filler is selected from the group consisting of carbon, carbon black, carbon nanotubes, graphite, graphene, silver, nickel, copper, gold, platinum, aluminum, iron, zinc, cobalt, lead, tin alloy, silver-coated copper, silver-coated graphite, silver-coated polymer, silver-coated aluminum, silver-coated glass, silver-coated carbon, silver-coated boron nitride, silver-coated aluminum oxide, silver-coated aluminum hydroxide, and mixtures thereof, more preferably selected from the group consisting of carbon black, carbon nanotubes, graphite, and mixtures thereof. The water-absorbent and conductive composition according to Claim 1.

5. The conductive filler is present in an amount of 10 to 35% by weight, preferably 12 to 33% by weight, more preferably 15 to 30% by weight, based on the total weight of the composition. The water-absorbent and conductive composition according to Claim 1.

6. The solvent has a boiling point of less than 235°C, preferably the solvent is selected from the group consisting of n-butanol, butyl carbitol, 1-methoxy-2-propanol acetate, isopropyl alcohol, butyl cellosolve, and mixtures thereof, more preferably selected from the group consisting of n-butanol, butyl carbitol, 1-methoxy-2-propanol acetate, and mixtures thereof. The water-absorbent and conductive composition according to Claim 1.

7. The solvent is present in an amount of 10 to 70% by weight, preferably 20 to 65% by weight, more preferably 30 to 60% by weight of the total weight of the composition, the water-absorbing and electrically conductive composition according to claim 1.

8. The water-absorbing and electrically conductive composition according to claim 1, further comprising a resin.

9. The resin is selected from the group consisting of vinyl resins, copolymers of vinyl chloride and vinyl acetate, thermoplastic polyurethane resins, polyvinyl butyral resins, (meth)acrylate resins, phenoxy resins, epoxy resins, polyester resins, and mixtures thereof, more preferably, the resin is selected from the group consisting of copolymers of vinyl chloride and vinyl acetate, polyvinyl alcohol resins, polyvinyl butyral resins, and mixtures thereof, the water-absorbing and electrically conductive composition according to claim 8.

10. The resin is present in an amount of 5 to 25% by weight, preferably 7.5 to 20% by weight, more preferably 9 to 15% by weight of the total weight of the composition, the water-absorbing and electrically conductive composition according to claim 8.

11. The water-absorbing and electrically conductive composition according to claim 1, further comprising an antifoaming agent.

12. The antifoaming agent is present in an amount of 0.1 to 1% by weight, preferably 0.1 to 0.7% by weight, more preferably 0.1 to 0.5% by weight of the total weight of the composition, the water-absorbing and electrically conductive composition according to claim 11.

13. A cured product of the water-absorbing and electrically conductive composition according to claim 1.

14. Use of the water-absorbing and electrically conductive composition according to claim 1, or the cured product according to claim 13 as a coating material.

15. Use of the water-absorbing and electrically conductive composition according to claim 1 or the cured product according to claim 13 as a sensor for monitoring erosion and / or corrosion.

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