WO2023207997A1

WO2023207997A1 - Two-component coating composition and method for preparing the same and coated article

Info

Publication number: WO2023207997A1
Application number: PCT/CN2023/090668
Authority: WO
Inventors: Hui Wu; Feng Xu
Original assignee: Sherwin-Williams (Nantong) Co. Ltd.
Priority date: 2022-04-27
Filing date: 2023-04-25
Publication date: 2023-11-02
Also published as: CN114921155A; TW202342655A

Abstract

The present application relates to a two-component coating composition, a method for preparing the same and a coated article. The two-component paint composition of the present application comprises component A and component B, characterized in that, the component A comprises at least one epoxy resin and at least one conductive filler, and the component B comprises at least one alicyclic amine curing agent, wherein the conductive filler is present in total amount of from 0.05 wt. %to 8 wt. %based on the total weight of the component A, and the component A has a viscosity at 25℃ of less than 140 KU, and the two-component coating composition has a volume solid content of greater than 60%. The two-component coating composition of the present application has high solid content and excellent application performance, and can provide a static electricity conductive anti-corrosion coating with good resistance to hot water.

Description

TWO-COMPONENT COATING COMPOSITION AND METHOD FOR PREPARING THE SAME AND COATED ARTICLE

TECHNICAL FIELD

The present application relates to a two-component coating composition and a method for preparing the same and a coated article. In particular, the present application relates to the static electricity conductive anti-corrosion technical field where good resistance to hot water, high solid content, and low viscosity are required.

BACKGROUND

With the rapid development of the economy, coatings applied to metal substrates face more and more problems and need to meet higher and higher requirements. For example, metal pipes or containers (such as oil pipelines, storage tanks, and tank trucks) used in chemical production and transportation are prone to suffering from issues related to corrosion and static electricity. Such pipes or containers are generally bulky and consume a large quantity of materials, and are usually manufactured from lower cost materials such as carbon steel rather than more expensive corrosion resistant alloys for economic reasons.

Substances (such as water, sulfur, sulfur dioxide, and carbon dioxide) present in chemicals such as petroleum are prone to corrosion on the inner surface of pipes or containers. Especially in low-latitude regions, for the transportation pipelines extending close to the earth's surface, the long-term exposure to the sun and the long-distance contact with the earth's surface further aggravate the corrosion effect. It is very difficult and expensive to replace a corroded pipe. Moreover, during the process of use, it is easy to accumulate static electricity, which will cause serious safety hazards.

Most of the current anti-corrosion conductive coatings on the market require adding a large amount of conductive fillers, resulting in unsatisfactory application performance of the coatings, and even require adding more diluents, resulting in increased VOC and reduced solid content. Moreover, currently commercially available anti-corrosion conductive coatings generally cannot meet the long-term corrosion requirements at relatively high temperatures (for example 90℃ or higher) .

SUMMARY

In view of this, there is a need for a conductive coating that not only has a high solid content and excellent application performance, but also can produce good corrosion resistance at high temperature.

The objective can be achieved by using the two-component coating composition as described herein.

The first aspect of the present application provides a two-component paint composition comprising component A and component B, characterized in that, the component A comprises at least one epoxy resin and at least one conductive filler, and the component B comprises at least one alicyclic amine curing agent, wherein the conductive filler is present in total amount of from 0.05 wt. %to 8 wt. %based on the total weight of the component A, and the component A has a viscosity at 25℃ of less than 140 KU, and the two-component coating composition has a volume solid content of greater than 60%.

The second aspect of the present application provides a method for preparing the two-component coating composition, comprising: mixing component A and component B, characterized in that, the component A comprises at least one epoxy resin and at least one conductive filler, and the component B comprises at least one alicyclic amine curing agent, wherein the conductive filler is present in total amount of from 0.05 wt. %to 8 wt. %based on the total weight of the component A, and the component A has a viscosity at 25℃ of less than 140 KU, and the two-component coating composition has a volume solid content of greater than 60%.

The third aspect of the present application provides a coated article, characterized in that the coated article comprises: a metal substrate having at least one major surface; and the two-component coating composition as described herein, applied on the at least one major surface of the metal substrate, or cured coating thereof.

The inventors have surprisingly found that the two-component coating composition described in this application is an anti-corrosion coating composition with conductive properties, which has high solid content and excellent application performance, and can provide a coatings with good resistance to hot water and excellent electroconductibility. In particular, the coating of the present application or its cured coating film has a relatively high volume solid content, does not blister after being soaked in hot water at 95 ℃ for a long time (for example, 240 hours or even longer) , and can have a surface resistance of from 10⁷ Ω to 10¹¹ Ω. The cured coating film of the coating of the present application does not blister in salt spray test for 1000 hours, in 5%sulfuric acid solution for 720 hours, in 5%sodium hydroxide solution for 720 hours, in 5%sodium chloride solution for 720 hours, and in crude oil at 60℃ for 720 hours.

Moreover, the coating of the present application has the advantages of low VOC (even solvent-free) and low cost, and is a healthy and environment-friendly product, which can be easily accepted by consumers.

The above summary of the present application is not intended to describe each disclosed embodiment or every implementation in this application. Illustrative embodiments are exemplified in more detail in the description that follows.

DETAILED DESCRIPTION

Selected definitions

As used herein, "a" , "an" , "the" , "at least one" , and "one or more" are used interchangeably. Thus, for example, a coating composition that comprises "an" additive can be interpreted to mean that the coating composition includes "one or more" additives. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Unless otherwise indicated, the terms “comprises” , “having” , “including” , “incorporating” , and variations thereof do not have a limiting meaning, but rather these terms in the description and claims are intended to be open-ended and non-limiting. For example, where compositions are described as having, including, or comprising specific components or fractions, or where processes are described as having, including, or comprising specific process steps, it is contemplated that the compositions or processes as disclosed herein may further comprise other components or fractions or steps, whether or not, specifically mentioned in this invention, as along as such components or steps do not affect the basic and novel characteristics of the invention, but it is also contemplated that the compositions or processes may consist essentially of, or consist of, the recited components or steps.

For the sake of brevity, only certain ranges are explicitly disclosed herein. However, it should be understood that any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, although not explicitly recited, every point or individual value within a range is expressly included in the range. Thus, every point or individual value may serve as its own lower or upper limit and be combined with any other point or individual value or any other lower or upper limit, to form a range not explicitly recited.

Unless otherwise indicated, the recitations of numerical ranges by endpoints include all numbers subsumed within that range. For example, a range of from 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. Furthermore, disclosure of a range includes disclosure of all subranges included within the broader range. For example, a range of from 1 to 5 discloses the subranges of from 1 to 4, from 1.5 to 4.5, from 1 to 2, etc. Thus, every point or individual value may serve as a lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range explicitly recited in the present application.

As used herein, “or” refers to an inclusive. That is, the phrase "A or B" means "A, B, or both A and B" , which can also be abbreviated as "A and/or B" . More specifically, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present) ; A is false (or not present) and B is true (or present) ; and both A and B are true (or present) . In contrast, the exclusive "or" is represented herein, for example, by terms such as "either A or B" and "one of A or B" .

When used in the context of "a coating applied on a surface or substrate, " the term "on" includes coatings that are applied directly or indirectly on the surface or substrate. Thus, for example, a coating applied on a primer coating on a substrate is regarded as a coating applied on the substrate.

The term "anti-corrosion coating composition" refers to a coating composition that, when applied to a metal substrate in one or more layers, forms a coating that can withstand the exposure to corrosive conditions for an extended period of time (such as three weeks or more in salt spray) without objectionable visible deterioration or corrosion.

The term “volume solid content" refers to the volume fraction of non-volatile compounds in a coating. It can be determined according to standard test methods commonly used in the art. For example, the volume solid content can be tested according to GB/T 9272-2007.

The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

Two-component coating composition

The two-component paint composition according to the first aspect of the present application comprises component A and component B, wherein the component A comprises at least one epoxy resin and at least one conductive filler, and the component B comprises at least one alicyclic amine curing agent, the conductive filler is present in total amount of from 0.05 wt. %to 8 wt. %based on the total weight of the component A, and the component A has a viscosity at 25℃ of less than 140 KU, and the two-component coating composition has a volume solid content of greater than 60%.

It can be seen that the coating in this application can contain a relatively low amount of conductive filler, and still achieve good static electricity conductivity and application performance. This is completely different from the common knowledge in the art. Before this application, in order to obtain a conductive coating, those skilled in the art usually need to add a relatively large amount (usually 15 wt. %, 25 wt. %or more) of conductive fillers, for example conductive mica powder and conductive barium sulfate. However, the inventors have found that adding such a large amount of conductive fillers (especially conductive mica powder) will cause the viscosity of the coating to rise, which seriously and adversely affects the sprayability, dispersibility and wettability of the coating to the substrate and thus results in a significantly deterioration of the application performance and even adversely affects the resistance to liquid medium and heat resistance of the coating. Moreover, conventional conductive fillers usually provide conductive performance by generating a conductive oxide layer on the surface of a body through surface modification. For example, mica and barium sulfate themselves are insulating, but conductive mica and barium sulfate can be produced after appropriate surface modification. However, such surface modification often results in a very high oil absorption value, which consumes film-forming resin and increases production costs.

It is desirable that the coatings of the present application preferably contain a relatively low amount of conductive fillers, especially surface-modified conductive fillers (for example, conductive mica powder and conductive barium sulfate) . In some embodiments, the total amount of the conductive filler in component A is not greater than 6 wt. %, preferably not greater than 5 wt. %, more preferably not greater than 3 wt. %, and even more preferably not greater than 2 wt.%, based on the total weight of the component A. In some embodiments, the total amount of the conductive filler in the component A is at least 0.08 wt. %, and preferably at least 0.1 wt. %, based on the total weight of the component A. As an example, the total amount of the conductive filler in the component A is 0.1-1.5 wt. %, such as 0.15 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 0.6 wt. %, 0.8 wt. %, 1.0 wt. %, 1.2 wt. %, 1.4 wt. %, and 1.5 wt. %, 2.5 wt. %, based on the total weight of the component A.

In some embodiments, the total amount of conductive mica powder and conductive barium sulfate in the component A is not greater than 5 wt. %, preferably not greater than 4 wt. %, and more preferably not greater than 3 wt. %, for example not greater than 2 wt. %, not greater than 1 wt. %and not greater than 0.5 wt. %, based on the total weight of the component A. Even more preferably, the component A is free of conductive mica powder and conductive barium sulfate.

In the two-component coating compositions described herein, conductive fillers having high electrical conductivity that do not adversely affect coating performance can be used. In some embodiments, the conductive filler at least comprises one or more conductive fillers selected from a group consisting of conductive carbon black, acetylene black, conductive mica powder, graphite, graphene, Ketjen black, carbon nanofibers, carbon nanotubes, conductive barium sulfate, and conductive titanium dioxide. Preferably, the conductive filler at least comprises one or more conductive fillers selected from a group consisting of graphite, graphene, carbon nanofibers, carbon nanotubes, and conductive titanium dioxide. More preferably, the conductive filler at least comprises one or more conductive fillers selected from a group consisting of graphene, carbon nanofibers, and carbon nanotubes. Even more preferably, the conductive filler comprises carbon nanotubes or carbon nanofibers.

The carbon nanotubes may be single-walled carbon nanotubes, multi-walled carbon nanotubes or combinations thereof, preferably comprise single-walled carbon nanotubes. Single-walled carbon nanotubes with a relatively high aspect ratio may be used. In some embodiments, the single-walled carbon nanotubes have an aspect ratio of at least 1500: 1, preferably at least 1800: 1, such as 2000-10000: 1. The carbon nanotubes may have a d10 of from 1.0 nm to 2.0 nm, a d50 of from 1.4 nm to 2.5 nm, and a d90 of from 1.6 nm to 2.7 nm. For example, carbon nanotubes may have a d10 of from 1.2 nm to 1.45 nm, a d50 of from 1.6 nm to 1.8 nm, and a d90 of from 1.9 to 2.2 nm. In addition, the inventors have further found that after being dispersed in the component A, the carbon nanotubes mainly exist in the form of bundle-like aggregates. Bundle-like aggregates may have a diameter of from 0.1 μm to 2 μm and a length of from 10 μm to 100 μm, for example a diameter of from 0.2 μm to 0.5 μm and a length of from 20 μm to 30 μm. As an example, carbon nanotubes may include the products in TUBALL MATRIX series from OCSiAl.

In the two-component coating composition described herein, the component A has a relatively low viscosity. Preferably, the viscosity at 25℃ is less than 120 KU, more preferably less than 115 KU, and more preferably less than 110 KU.

The two-component coating composition described herein has a relatively high solid content. Preferably, the two-component coating composition has a volume solid content of greater than or equal to 65%, more preferably greater than or equal to 70%, further preferably greater than or equal to 75%, and even more preferably greater than or equal to 80%.

In the two-component coating composition described herein, the epoxy resin may comprise phenolic epoxy resin, bisphenol A epoxy resin or their combination. In some embodiments, the phenolic epoxy resin has an epoxy equivalent weight of less than 300 g/eq, preferably less than 250 g/eq, and more preferably less than 200 g/eq. For example, the phenolic epoxy resin may have an epoxy equivalent weight of about 160 g/eq, about 165 g/eq, about 170 g/eq, about 185 g/eq, about 190 g/eq, about 195 g/eq. In some embodiments, the bisphenol A epoxy resin may have an epoxy equivalent weight of less than 300 g/eq, preferably less than 250 g/eq, and more preferably less than 200 g/eq. For example, the bisphenol A epoxy resin may have an epoxy equivalent weight of about 180 g/eq, about 185 g/eq, about 190 g/eq, or about 195 g/eq.

In the two-component coating composition described herein, by combining phenolic epoxy resin with bisphenol A epoxy resin and controlling their ratio, heat resistance, chemical stability and corrosion resistance can be further obtained while maintaining excellent adhesion and strength and a relatively low cost of coating. In some embodiments, the weight ratio of bisphenol A epoxy resin to phenolic epoxy resin is from 1: 1 to 10: 1, preferably from 1.5: 1 to 8: 1, and preferably from 2: 1 to 5: 1, for example 3: 1, 4: 1, 6: 1, and 7: 1.

Based on the total weight of the component A, the amount of epoxy resin may be 20-48 wt. %, preferably 25-45 wt. %, and more preferably 30-40 wt. %, such as about 35 wt. %, about 28 wt. %.

The two-component coating compositions described herein are capable of providing coatings with excellent electrical conductivity that meet the industry's static electrical conductivity requirements for coatings on metallic substrates. In some embodiments, the cured film obtained after mixing the component A and the component B and applying has a surface resistivity of from 1×10² Ω to 1×10¹¹ Ω, preferably from 1×10⁵ Ω to 1×10¹⁰ Ω, and more preferably from 1×10⁷ Ω to 1×10⁹ Ω, such as 1×10⁸ Ω. The surface resistivity described herein can be measured according to common standards, for example according to GB/T 1410-2006. Unless otherwise stated, surface resistivity is measured at 23±2℃ and 50±5%relative humidity.

The two-component coating composition may also contain a silane coupling agent. In some embodiments, the coupling agent includes a silane compound having the following Formula I:

wherein each X₁ is independently selected from a group consisting of -Cl, -OCH₃, -OCH₂CH₃, -OC₂H₄OCH₃, -OSi (CH₃) ₃ and -OCOCH₃; and

Y₁ is an alkyl group terminated with -Cl, -NH₂, -SH, -OH, epoxy, -N₃, γ-methacryloxypropyl or isocyanate group.

In some embodiments, the silane coupling agent has a molecular weight of from 100 to 800 Daltons, preferably from 200 to 400 Daltons, such as about 150 Daltons, about 250 Daltons, or 300 Daltons.

Preferably, the silane coupling agent is an epoxy silane coupling agent. For example, in Formula I, Y₁ is an alkyl group terminated by an epoxy group.

The inventors have found that in one aspect, the active group of the silane coupling agent reacts with the metal oxide on the metal surface or water on the surface to form a hydrogen bond, which improves the adhesion of the coating to the metal substrate; in another aspect, the silane can react with the amine curing agent in the coating to make the coating more dense. In particular, the benefits in these two aspects are more prominent when epoxy silane coupling agent is used. More surprisingly, the inventors have found that when an epoxy silane coupling agent is added to the two-component coating composition described herein, the hot water resistance of the cured coating is significantly improved with excellent reproducibility, which makes the coating suitable for large-scale industrial applications.

More importantly, in some embodiments, the beneficial effects described above can be observed by adding a relatively low amount of silane coupling agent. Based on the total weight of the component A, the amount of silane coupling agent may be from 0.2 wt. %to 2 wt. %, preferably from 0.3 wt. %to 1.8 wt. %, and more preferably from 0.5 wt. %to 1.5 wt. %. For example, the amount of the silane coupling agent may be about 0.4 wt. %, about 0.5 wt. %, about 0.6 wt. %, about 0.8 wt. %, about 1.0 wt. %, about 1.2 wt. %.

In the two-component coating composition according to the present application, the component A may contain pigments and fillers. Examples of pigments and fillers may include talc powder, quartz powder, barium sulfate, mica powder, wollastonite powder, titanium dioxide, iron red powder, zinc phosphate, zinc oxide, aluminum tripolyphosphate, modified zinc phosphate, and kaolin. In some embodiments, the component A includes one or more of talc powder, quartz powder, barium sulfate, titanium dioxide and wollastonite powder. According to needs, anti-corrosion functional fillers such as aluminum tripolyphosphate and modified zinc phosphate may be added to greatly improve the anti-corrosion performance.

In some embodiments, the component A comprises one or more of quartz powder, barium sulfate, wollastonite powder, and talc powder with a particle size of from 100 mesh to 1500 mesh. In some embodiments, the component A comprises talc powder with a particle size of from 200 mesh to 1000 mesh, preferably from 300 mesh to 800 mesh, more preferably from 400 mesh to 600 mesh. The inventors have surprisingly found that by adjusting particle size of the pigments and fillers, the surface resistivity of the cured coating can be further improved.

Based on the total weight of the component A, the amount of the pigments and fillers may be from 40 wt. %to 70 wt. %, preferably from 45 wt. %to 65 wt. %, and more preferably from 50 wt. %to 60 wt. %. For example, the amount of the pigments and fillers may be about 43 wt. %, about 48 wt. %, about 53 wt. %, about 58 wt. %, or about 62 wt. %.

In the two-component coating composition according to the present application, the component A may also comprise customary additives which do not adversely affect the two- component coating composition or the cured coating obtained therefrom. Suitable additives include, for example, those that will improve the processability or manufacturability of the composition, enhance the aesthetics of the composition, improve certain functional properties or characteristics (such as adhesion to the substrate) of the coating composition or cured composition derived therefrom, or those reagents that may reduce costs. Additives that may be included are, for example, lubricants, coalescents, wetting agents, plasticizers, defoamers, colorants, antioxidants, flow control agents, thixotropic agents, matting powders, dispersants, adhesion promoters, thickeners, pH regulators, curing catalysts or combinations thereof. Each of optional ingredients is present in an amount sufficient to serve its intended purpose, but preferably, such an amount does not adversely affect the two-component coating composition or the cured coating therefrom. In some preferred embodiments, component A may contain defoamers, film-forming aids, wetting agents, leveling agents, thickeners, matting powders or any combination thereof as conventional additives. According to the application, the total amount of customary additives may be 0.1 wt. %to 25 wt. %, for example about 10 wt. %, relative to the total weight of component A. In some embodiments, the amount of dispersant may be from 0.1 wt. %to 1 wt. %, the amount of antifoaming agent may be from 0.1 wt. %to 0.3 wt. %, the amount of wetting agent may be from 0.5 wt. %to 2 wt. %, and the amount of leveling agent may be from 0.5 wt. %to 2 wt. %, alternatively, the amount of the thixotropic agent may be from 0.1 wt. %to 1 wt. %.

The two-component coating composition of the present application has a relatively low amount of volatile components. In some embodiments, the component A comprises from 0 to 15 wt. %, preferably from 0 wt. %to 12 wt. %of organic solvent, based on the total weight of the component A. For example, based on the total weight of the component A, the component A comprises about 2 wt. %, 5 wt. %, 7 wt. %, or 10 wt. %of organic solvent. Examples of organic solvent include monohydric or polyhydric alcohols such as propanol, butanol, hexanol, benzyl alcohol; glycol ethers or esters such as dipropylene glycol dialkyl ethers and diethylene glycol dialkyl ethers each having a C1-C6 alkyl group, ethoxypropanol, butyl glycol; glycols, such as ethylene glycol, propylene glycol; and ketones, such as methyl ethyl ketone, acetone, cyclohexanone; N-methylpyrrolidone, N-ethylpyrrolidone; aromatic or aliphatic hydrocarbons such as toluene, xylene, or straight or branched aliphatic C6-C12 hydrocarbons. In some embodiments, the organic solvent includes xylene, butanol, propylene glycol methyl ether, benzyl alcohol, or any combination thereof.

In some embodiments, the component A comprises:

25-45 wt. %of the epoxy resin,

0.1-2 wt. %of the conductive filler,

40-70 wt. %of pigment and filler,

0.2-2 wt. %of silane coupling agent, and

0-15 wt. %of organic solvent.

In the two-component coating composition described herein, the component B comprises at least one alicyclic amine curing agent. The inventors have found that compared with other curing agents (for example, polyamide curing agent, cardanol curing agent, aliphatic polyamine curing agent, aromatic amine curing agent) , the alicyclic amine curing agent has a ring structure and has excellent heat resistance and can react with epoxy resin to give a coating with dense network structure, which can prevent metal substrate from being corroded due to the penetration of hot water. By using a suitable alicyclic amine curing agent, the hot water resistance of the coating may be further improved.

In some embodiments, the alicyclic amine curing agent may have an active hydrogen equivalent of from 80 to 140 g/eq, and preferably from 90 to 110 g/eq, such as an active hydrogen equivalent of about 95 g/eq, about 100 g/eq, about 105 g/eq eq, about 110 g/eq, and about 115 g/eq. Examples of the alicyclic amine curing agents include JH 5933 from Jiadida New Materials, ARADUR 265-1 from Huntsman, ANCAMINE 2719 from Evonik, ANCAMINE 2280 and ANCAMINE 2143 from Evonik.

The inventors have found that by using a combination of alicyclic amine curing agent (especially JH 5933 curing agent) and epoxy silane coupling agent, the obtained cured coating exhibits particularly excellent hot water resistance in the test in hot water at 95℃ , while retaining or improving other properties of the coating.

The component B may contain from 0 wt. %to 15 wt. %of organic solvent. The above descriptions about the organic solvent contained in the component A also apply to the organic solvent contained in the component B. For brevity, they are not repeated here. On the basis of this disclosure, those skilled in the art can reasonably determine and select the amount of organic solvent contained in component B according to actual needs.

In the two-component coating composition described herein, the relative amounts of component A and component B can be adjusted as needed. In some embodiments, volume ratio of the component A to the component B is from 1: 1 to 10: 1, preferably from 1: 1 to 10: 1, and more preferably from 2: 1 to 8: 1, such as 3: 1, 4: 1, 5: 1, 6: 1, and 7: 1.

According to the present application, the two-component coating composition can be prepared by simply mixing components A and B in a predetermined ratio in a mixing device before application. The resulting mixed coating composition may be applied using a variety of methods familiar to those skilled in the art, including spraying (for example, air-assisted, airless, or electrostatic spraying) , brushing, rolling, flooding, and dipping. In an embodiment of the present application, the mixed coating composition is applied by spraying. The coating compositions may be applied in various wet film thicknesses. In embodiments of the present application, the wet film thickness preferably provides a dry film thickness of from about 13 μm to about 260 μm, and more preferably from about 75 to about 150 μm. Curing may be achieved by air drying the applied coating or by accelerating curing in various drying devices familiar to those skilled in the art, such as an oven.

Method for preparing two-component coating composition

The content described in the context of two component coating compositions also applies to the method for preparing two component coating composition.

Coated article

The two-component coating composition of the present application may be applied directly on the substrate, and may also be applied on a coating on the substrate. In some embodiments, the two-component coating composition of the present application may be used in conjunction with a primer. In this case, the article of the present application comprises a substrate, a primer layer and a coating formed from the two-component coating composition of the present application. In some other embodiments of the present application, the two-component coating composition of the present application may be applied without a primer and coated directly on the major surface of the substrate.

As the metal substrate used to make the article of the present application, any suitable metal substrate known in the art may be used. By way of illustration, the metal substrate may comprise iron substrate, aluminum substrate, carbon steel or stainless steel.

According to the present application, the coated article may be prepared, for example, by the following steps: (1) providing a polished metal substrate; (2) using a coating process to sequentially apply one or more layers of the coating compositions described herein followed by curing to give a cured coating.

The metal articles of the present application may be used in the following end applications including, but not limited to, refrigerated containers and unrefrigerated shipping containers (e.g., dry cargo containers) from suppliers or manufacturers including China International Marine Containers (CIMC) , Graaff Transportsysteme Gmbh, Maersk Line and others that will be familiar to persons having ordinary skill in the art, chassis, trailers including semitrailers, rail cars, truck bodies, ships, bridges, petrochemical storage tank interiors, building skeletons, and other prefabricated or site-fabricated metal articles needing temporary indoor or outdoor corrosion inhibition during fabrication. Additional uses include metal angles, channels, beams (e.g., I-beams) , pipes, tubes, plates and other components that may be welded into these and other metal articles.

Examples

The disclosure in the present application will be described in further detail with reference to the following examples. However, it is to be understood that the following examples of the present application are only intended to be illustrative of the present application, and are not intended to limit the invention, because it would be obvious to those skilled in the art that various modifications and changes can be made within the scope of the disclosure of the present application. All parts, percentages, and ratios reported in the following examples are by weight unless otherwise stated. Moreover, all reagents used in the examples were commercially available and used without further treatment.

Test Methods

Volume solid content: was tested according to GB/T 9272-2007.

Viscosity: was tested according to GB/T 9269-2009, at 25℃, using a Stormer viscometer (ranging from 40 KU to 141 KU) , and expressed in KU. According to needs, Brookfield viscosity may be tested by using a Brookfield rotational viscometer with the 6#spindle at 25℃ with a rotation speed of 30 rpm, and expressed in cp (or mPa·s) .

Surface resistivity: was tested according to GB/T 1410-2006 at 23±2℃ and 50±5%relative humidity.

Hot water resistance: was tested according to GB 9274-1988 by placing a test sample in hot water at 95℃ for 240 hours and then taking it out to observe whether there are any bad conditions such as blistering, cracking, and falling off.

Salt spray resistance: was tested according to GB/T 1771-2007, by carrying out salt spray for 1000 hours to observe whether there are any bad conditions such as blistering, cracking, and falling off.

Anti-corrosion performance: was tested according to GB 9274-1988, by placing a test sample in 5%sulfuric acid for 720 hours, 5%sodium hydroxide for 720 hours, 5%sodium chloride solution for 720 hours or crude oil at 60℃ for 720 hours according to the needs, then taking it out to observe whether there are any bad conditions such as blistering, cracking, and falling off.

Example 1

A two-component coating composition was prepared in Example 1.

(1) Preparation of component A: 0.2 parts of conductive filler TUBALL MATRIX 301 from OCSiAl was added to 34.0 parts of epoxy resin (epoxy resin YD-128 and YDPN-638X80 from Guodu Chemical, with a weight ratio of 10: 1) , stirred for dispersing the conductive filler evenly. Then, under stirring, 10.0 parts of titanium dioxide, 25.0 parts of talc powder with an average particle diameter of 1250 mesh, 23.0 parts of barium sulfate, 1.3 parts of additives, 0.5 parts of silane coupling agent A-187 and 6.0 parts of solvent were added. After uniform dispersion, component A was obtained. The component A has a viscosity at 25℃ of 105.4 KU.

(2) Preparation of component B: 2 parts of solvent was added to 98 parts of alicyclic amine curing agent JH 5933 commercially available from Jiadida New Materials, and after uniform dispersion, component B was obtained.

(3) Mixing component A and component B at a volume ratio of 4: 1.

The resulting coating was applied to a steel plate and cured. It was found in coating performance tests that the obtained coating had a volume solid content of 79%, and the cured film had a surface resistivity of 108 Ω, and did not blister in salt spray test for 1000 hours, in 5%sulfuric acid solution for 720 hours, in 5%sodium hydroxide solution for 720 hours, in 5%sodium chloride solution for 720 hours, and in crude oil at 60℃ for 720 hours. Moreover, after soaking in hot water at 95℃ for 240 hours, the adhesion of the film on the steel plate surface was still as high as 14.86MPa.

Example 2

A two-component coating composition was prepared in Example 2.

(1) Preparation of component A: 0.15 parts of conductive filler TUBALL MATRIX 301 was added to 28.0 parts of epoxy resin (YD-128 and Epalloy 8240, with a weight ratio of 2: 1) , stirred for dispersing the conductive filler evenly. Then, under stirring, 6.0 parts of titanium dioxide, 11.9 parts of talc powder with an average particle diameter of 425 mesh, 23.65 parts of quartz powder, 17.0 parts of wollastonite powder, 2.0 parts of BC-C10 conductive mica powder from Junjiang, 1.3 parts of additives, 0.5 parts of silane coupling agent A-187 and 9.5 parts of solvent were added. After uniform dispersion, component A was obtained. The component A has a viscosity at 25℃ of 117.0 KU.

(2) Preparation of component B: 20 parts of ARADUR 265-1 curing agent was added to 80 parts of alicyclic amine curing agent JH 5933, and after uniform dispersion, component B was obtained.

(3) Mixing component A and component B at a volume ratio of 4: 1.

The resulting coating was applied to a steel plate and cured. It was found in coating performance tests that the obtained coating had a volume solid content of 80.7%, and the cured film had a surface resistivity of 10⁹ Ω, and did not blister in salt spray test for 1000 hours, in 5%sulfuric acid solution for 720 hours, in 5%sodium hydroxide solution for 720 hours, in 5%sodium chloride solution for 720 hours, and in crude oil at 60℃ for 720 hours.

Example 3

Example 1 was repeated, except that barium sulfate was replaced with quartz powder. The measured surface resistivity was 10⁸Ω.

Example 4

Example 1 was repeated, but without adding a silane coupling agent. The coating did not blister after being soaked in hot water at 95℃ for 144 hours, but blistered apparently after 240 hours.

Example 5

Example 1 was repeated, except that 1 part of the silane coupling agent was added. The coating did not blister after being soaked in hot water at 95℃ for 1000 hours.

Example 6

In order to test the effect of pigments and fillers with different particle sizes on the electrical conductivity, in Example 6-1, Example 1 was repeated, but talcum powder with 1250 mesh and 0.125 parts of carbon nanotubes were used. In Example 6-2, Example 1 was repeated, but talcum powder with 425 mesh and 0.125 parts of carbon nanotubes were used. The surface resistivity results of cured paint films were measured, showing 10¹² Ω in Example 6-1, while 10⁹ Ωin Example 6-2.

Comparative Example 1

Commercially available Tankgaurd NCV static conductive two-component coating composition was used. The coating was applied to a steel plate and cured. It was found in coating performance tests that the cured film had a surface resistivity of 1011 Ω, and did not blister in hot water at 95℃ for 48-96 hours, in 5%sulfuric acid solution for 720 hours, in 5%sodium hydroxide solution for 720 hours, in 5%sodium chloride solution for 720 hours, and in crude oil at 60℃ for 720 hours, but blistered apparently in salt spray test for 1000 hours.

Comparative Example 2

Example 1 was repeated, but 23 parts of barium sulfate was replaced with 23 parts of conductive mica. The obtained component A had a viscosity at 25℃ of higher than the maximum measured value of the Stormer viscometer (greater than 140 KU) , and a viscosity of 17070 cP as measured by using the Brookfield rotational viscometer. In order to facilitate the subsequent application, it was required to add a large amount of diluent to adjust the appropriate viscosity.

Comparative Example 3

Example 1 was repeated, except that no silane coupling agent was added and the alicyclicamine curing agent was replaced with polyamide curing agent. The coating blistered after being soaked in hot water at 95℃ for 96 hours.

Comparative Example 4

Example 1 was repeated, except that no silane coupling agent was added and the alicyclicamine curing agent was replaced with cardanol curing agent. The coating slightly blistered after being soaked in hot water at 95℃ for 144 hours.

Comparative Example 5

Example 1 was repeated, except that no silane coupling agent was added and the alicyclicamine curing agent was replaced with aliphatic curing agent. The coating blistered after being soaked in hot water at 95℃ for 96 hours.

While the invention has been described with reference to a number of embodiments and examples, those of ordinary skill in the art would recognize that other embodiments can be devised based on this disclosure. It will be readily apparent to those skilled in the art that changes may be made in the present application without departing from the principles disclosed in the foregoing specification. For example, without departing from the principles disclosed in the foregoing description, the technical solutions obtained by combining multiple features or preferred implementations described herein shall be understood to belong to the contents recorded herein. Such modifications are to be considered as included within the following claims unless the claims expressly state otherwise. Accordingly, the embodiments described in detail herein are illustrative only and do not intend to limit the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Claims

A two-component paint composition, comprising component A and component B, characterized in that, the component A comprises at least one epoxy resin and at least one conductive filler, and the component B comprises at least one alicyclic amine curing agent.

wherein the conductive filler is present in total amount of from 0.05 wt. %to 8 wt. %based on the total weight of the component A, and the component A has a viscosity at 25℃ of less than 140 KU, and

the two-component coating composition has a volume solid content of greater than 60%.
The two-component coating composition according to claim 1, characterized in that a cured film obtained after mixing the component A and the component B and applying has a surface resistivity of from 1×10² Ω to 1×10¹¹ Ω.
The two-component coating composition according to claim 1 or 2, characterized in that a total amount of conductive mica powder and conductive barium sulfate in the component A is not greater than 5 wt. %based on the total weight of the component A.
The two-component coating composition according to any one of claims 1 to 3, characterized in that the conductive filler at least comprises one or more conductive fillers selected from a group consisting of conductive carbon black, acetylene black, conductive mica powder, graphite, graphene, Ketjen black, carbon nanofibers, carbon nanotubes, conductive barium sulfate, and conductive titanium dioxide.
The two-component coating composition according to any one of claims 1 to 4, characterized in that the conductive filler comprises single-walled carbon nanotubes with an aspect ratio of at least 1500: 1.
The two-component coating composition according to any one of claims 1 to 5, characterized in that the at least one epoxy resin comprises phenolic epoxy resin, bisphenol A epoxy resin or their combination.
The two-component coating composition according to any one of claims 1 to 6, characterized in that the at least one epoxy resin comprises bisphenol A epoxy resin with epoxy equivalent weight of less than 300 g/eq and phenolic epoxy resin with epoxy equivalent weight of less than 300 g/eq.
The two-component coating composition according to claim 6 or 7, characterized in that a weight ratio of bisphenol A epoxy resin to phenolic epoxy resin is from 1: 1 to 10: 1.
The two-component coating composition according to any one of claims 1 to 8, characterized in that the two-component coating composition further comprises a silane coupling agent.
The two-component coating composition according to claim 9, characterized in that the silane coupling agent is an epoxy silane coupling agent.
The two-component coating composition according to any one of claims 1 to 10, characterized in that the component A comprises one or more of quartz powder, barium sulfate, wollastonite powder, and talc powder with a particle size of from 100 mesh to 1500 mesh.
The two-component coating composition according to any one of claims 1 to 11, characterized in that a volume ratio of the component A to the component B is from 1: 1 to 10: 1.
The two-component coating composition according to any one of claims 1 to 12, characterized in that based on the total weight of the component A, the component A comprises:

25-45 wt. %of the epoxy resin,

0.1-2 wt. %of the conductive filler,

40-70 wt. %of pigment and filler,

0.2-2 wt. %of silane coupling agent, and

0-15 wt. %of organic solvent.
A method for preparing the two-component coating composition according to any one of claims 1 to 13, comprising:

mixing component A and component B,

characterized in that, the component A comprises at least one epoxy resin and at least one conductive filler, and the component B comprises at least one alicyclic amine curing agent.

wherein the conductive filler is present in total amount of from 0.05 wt. %to 8 wt. %based on the total weight of the component A, and the component A has a viscosity at 25℃ of less than 140 KU, and

the two-component coating composition has a volume solid content of greater than 60%.
A coated article, characterized in that the coated article comprises:

a metal substrate having at least one major surface; and

the two-component coating composition according to any one of claims 1 to 13, applied on the at least one major surface of the metal substrate, or cured coating thereof.
The coated article according to claim 15, characterized in that the metal substrate comprises iron substrate, aluminum substrate, carbon steel or stainless steel.
The coated article according to claim 15 or 16, characterized in that the cured coating of the coated article has a surface resistance of from 10⁷ Ω to 10¹¹ Ω, and does not blister in hot water at 95℃ for 240 hours, in salt spray test for 1000 hours, in 5%sulfuric acid solution for 720 hours, in 5%sodium hydroxide solution for 720 hours, in 5%sodium chloride solution for 720 hours, and in crude oil at 60℃ for 720 hours.