CN115558325A

CN115558325A - One-part aqueous conductive coating composition

Info

Publication number: CN115558325A
Application number: CN202211338952.5A
Authority: CN
Inventors: 周春燕; 窦萌; 宋立明; 杨宇润; 孟祥美
Original assignee: PPG Coatings Tianjin Co Ltd
Current assignee: PPG Coatings Tianjin Co Ltd
Priority date: 2022-10-28
Filing date: 2022-10-28
Publication date: 2023-01-03

Abstract

Disclosed is a one-component aqueous conductive coating composition comprising a resin component and a conductive pigment filler, wherein the resin component comprises a high molecular weight acrylic resin, a tackifying resin, and a polyolefin resin, the high molecular weight acrylic resin has a weight average molecular weight of greater than 75,000, and the polyolefin resin is present in an amount of no more than 20wt% based on the solids content of the resin component. Also disclosed is a coated substrate comprising a substrate and the one-part aqueous conductive coating composition described above applied to at least a portion of the substrate.

Description

One-part aqueous conductive coating composition

Technical Field

The invention relates to the field of coatings, in particular to a one-component water-based conductive coating, which is especially used for untreated polar substrates and/or non-polar substrates.

Background

For one-component waterborne coatings on untreated PP substrates, waterborne polyolefin latex (PO) is a viable solution to achieve good adhesion. The formulations that are currently commercialized have very high polyolefin contents, which leads to drawbacks in terms of cost and application and impaired performance compared to other substrates.

In one-component aqueous coating compositions, increasing the polyolefin content can result in more excellent properties for untreated PP substrates, however, polyolefins do not facilitate adhesion of ABS/PC + ABS, and in particular under severe conditions, recoating.

On the other hand, high polyolefin contents lead to high costs, the corresponding suppliers are also very limited, only two japanese suppliers are present, and the productivity is insufficient.

Based on the above technical background, there is a need to develop a new technology that can combine excellent performance with low cost.

Disclosure of Invention

The present inventors have conducted extensive studies and developed a one-component aqueous conductive coating composition having a reduced polyolefin content, and having excellent adhesion properties equivalent to those of the prior art coatings having a high polyolefin content, and achieving even more excellent adhesion properties under severe conditions, such as excellent adhesion after steam spraying, water immersion, and oil immersion. Moreover, the coating composition of the invention reduces the cost by 20 to 25 percent compared with the prior art.

The invention provides a one-component water-based conductive coating composition, which comprises a resin component and a conductive pigment filler, wherein the resin component comprises a high-molecular-weight acrylic resin, a tackifying resin and a polyolefin resin, the high-molecular-weight acrylic resin has a weight average molecular weight of more than 75,000, and the content of the polyolefin resin based on the solid content of the resin component is not more than 20wt%.

The invention also provides a coated substrate comprising a substrate and a coating composition applied to at least a portion of the substrate, wherein the coating composition is a one-component aqueous conductive coating composition comprising a resin component and a conductive pigment filler, wherein the resin component comprises a high molecular weight acrylic resin, a tackifying resin, and a polyolefin resin, the high molecular weight acrylic resin having a weight average molecular weight greater than 75,000, and the polyolefin resin being present in an amount of no more than 20wt% based on the solids content of the resin component.

The features and advantages of the present invention will be presented in more detail in the following detailed description of embodiments.

Detailed Description

As used herein, unless otherwise expressly specified, the numbers expressing, for example, values, ranges, amounts or percentages used in the specification and claims are to be understood as being modified in all instances by the term "about", even if the term is not expressly indicated. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims herein are approximations that may vary depending upon the desired properties to be obtained by the present invention.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently has certain errors. This error is a corollary to the standard deviation found in its corresponding measurement method.

Moreover, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

In this application, the use of the singular includes the plural and plural encompasses singular, unless expressly stated otherwise. In addition, in this application, the use of "or" means "and/or" unless explicitly stated otherwise, even though "and/or" may be explicitly used in some cases. In addition, in this application, the use of "a" or "an" means "at least one" unless explicitly stated otherwise. For example, "a" polymer, "a" coating, and the like refer to one or more of any of these items. Also, as those skilled in the art will recognize, features of one embodiment may be used with other embodiments even if not explicitly stated.

As used herein, the term "coating" refers to a fluid substance that is applied to a substrate surface and cured by natural or artificial means to form a coating that covers the substrate surface and provides protection and decoration.

As used herein, "waterborne" means that the coating composition comprises at least 50% by weight water in the solvent.

As used herein, the term "one-pack" means that all film-forming materials, pigments, fillers, solvents, adjuvants, etc. of the coating composition are packaged in one container, and thus has advantages such as convenience in storage and use.

As used herein, "electrically conductive" means that when the coating composition is applied to the surface of a substrate, the surface resistance of the substrate can be substantially reduced, facilitating the electrostatic spraying of subsequent coatings. A coating formed from the one-part aqueous conductive coating composition according to the present invention may have an electrical resistance of less than 500K Ω after dehydration at 80 ℃ for 5 min. The resistance can be measured by a Ransburg resistance tester.

The one-part aqueous conductive coating composition according to the present invention is a thermosetting coating composition, that is, the coating composition is cured to a film by heating after being applied to a substrate surface. In this context, the term "curing" refers to the process of a material becoming fixed and no longer flowing. Suitably, the one-part aqueous conductive coating composition according to the present invention may be cured at 40 to 80 ℃ for 5 to 10 min.

The one-part aqueous conductive coating composition according to the present invention is a thermoplastic composition. As used herein, the term "thermoplastic" means that the components of the coating composition are not covalently bonded after curing and that the resulting coating film softens when exposed to heat. Herein, thermoplastic compositions and non-crosslinked compositions may be used interchangeably.

The one-component aqueous conductive coating composition according to the present invention has a solid content of 30 to 35%. As used herein, the term "solids content" refers to the ratio of the mass remaining after drying and baking of a coating composition to the mass of the coating composition, which can be determined according to GB/T1725-79 coating solids assay.

The invention provides a single-component water-based conductive coating composition, which comprises a resin component and a conductive pigment and filler, wherein the resin component comprises a high molecular weight acrylic resin, a tackifying resin and a polyolefin resin, the high molecular weight acrylic resin has a weight average molecular weight of more than 75,000, and the content of the polyolefin resin based on the solid content of the resin component is not more than 20wt%.

The term "resin component" may also be referred to herein as a "film-forming resin" and refers to a resin capable of forming a self-supporting, continuous coating film in a coating composition, at least in the horizontal plane. As used herein, the "solids content of the resin component" refers to the sum of the solids weights of the film-forming resins.

Herein, the "acrylic resin" refers to a polymer based on a (meth) acrylic monomer. By "essential" is meant that the (meth) acrylic monomer in the polymer constitutes at least about 70wt%, for example at least about 80wt%, such as at least about 90wt% of all polymerized monomers.

The acrylic resin used in the present invention has a high molecular weight. The high molecular weight acrylic resin imparts increased cohesion to the coating composition. Suitably, the acrylic resin has a weight average molecular weight (Mw) of greater than 75,000, such as a Mw of greater than 100,000. The weight average molecular weight (Mw) can be determined by gel permeation chromatography using appropriate standards, such as polystyrene standards.

The acrylic resin is also selected with consideration of the impact on other mechanical properties in order to meet the overall performance requirements of the coating.

The acrylic resin used in the present invention may have a glass transition temperature (Tg) of less than 0 ℃, such as less than-10 ℃, not more than-20 ℃, for example-20 to-40 ℃. The glass transition temperature may be determined by methods conventional in the art, for example, by Differential Scanning Calorimetry (DSC), and for the test conditions, the test conditions may be determined using test conditions conventional in the art, for example, by increasing the temperature from 0 ℃ to 150 ℃ at a rate of 10K/min, decreasing the temperature from 150 ℃ to 0 ℃, increasing the temperature from 0 ℃ to 150 ℃, and increasing the nitrogen gas rate to 50ml/min. A particular range of glass transition temperatures can provide coatings with good flexibility and low temperature flexibility.

The acrylic resin used in the present invention may have an acid value of not more than 10mgKOH/g, such as an acid value of 5 to 8 mgKOH/g. The "acid number" refers to the number of milligrams of potassium hydroxide required to neutralize the free acid in 1 gram of resin. A suitable acid value avoids an undesirable increase in the hydrophilicity of the coating, which in turn leads to a decrease in the water resistance.

The acrylic resins suitable for use in the present invention may be in the form of dispersions or emulsions having a solids content of from 30 to 70% by weight, such as from 40 to 60% by weight. The "solids content" refers to the mass remaining after evaporation as a percentage of the mass of the original dispersion/emulsion.

The one-part aqueous conductive coating composition according to the present invention may include about 10wt% or more, such as about 15wt% or more, for example, about 20wt% or more, of the acrylic resin, and/or may include about 40wt% or less, such as about 35wt% or less, for example, about 30wt% or less, of the acrylic resin, based on the resin component solids of the one-part aqueous conductive coating composition. The acrylic resin may be present in the composition in a range of about 10 to 40 weight percent, such as about 15 to 35 weight percent, for example about 20 to 30 weight percent, or any other combination using these extremes, based on the resin component solids content of the one-part aqueous conductive coating composition.

The tackifying resins used in the present invention may include rosin resins and/or terpene-based resins. Examples of the rosin resin include, but are not limited to, natural rosin, polymerized rosin, modified rosin modified with maleic acid, fumaric acid, (meth) acrylic acid, and the like, and rosin derivatives such as esterified products of the above rosins, phenol modified products, and hydrogen adducts, and the like. Examples of the terpene-based resin include, but are not limited to, resins composed of α -pinene, β -pinene, limonene, dipentene, terpene phenol, terpene alcohol, and/or terpene aldehyde, and the like, and derivatives of the above resins, such as hydrogen adducts.

Tackifying resins can provide coatings with enhanced initial adhesion, but also affect the coating performance, substrate wetting properties, and water resistance of the coating, thereby adversely reducing adhesion. For this reason, the choice of tackifying resins requires a compromise of properties.

The tackifying resins used in the present invention have a Mw below 1,000, suitably below 800, such as below 600. The Mw can be determined by gel permeation chromatography using appropriate standards, such as polystyrene standards.

Suitably, the tackifying resins used in the present invention have a softening point of less than 100 ℃, for example a softening point of less than 90 ℃, or a softening point of less than 80 ℃, or a softening point of less than 70 ℃. The softening point may be determined by reference to GB 8146. The softening point within this range does not deteriorate the coating property of the coating material and the wetting property of the substrate while ensuring the advantageous properties of the tackifier resin.

Suitably, the tackifying resin used in the present invention has an acid value of not more than 10mgKOH/g, such as an acid value of from 5 to 8 mgKOH/g. The "acid number" refers to the number of milligrams of potassium hydroxide required to neutralize the free acid in 1 gram of resin. The acid value contributes to the water resistance of the coating.

Tackifying resins suitable for use in the present invention may be in the form of a dispersion or emulsion having a solids content of 30 to 70 weight percent, such as 40 to 60 weight percent. The "solids content" refers to the mass remaining after evaporation as a percentage of the mass of the original dispersion/emulsion.

The one-part aqueous conductive coating composition according to the present invention may include about 10wt% or more, such as about 15wt% or more, for example, about 20wt% or more of the tackifying resin, and/or may include about 40wt% or less, such as about 35wt% or less, for example, about 30wt% or less of the tackifying resin, based on the resin component solids amount of the one-part aqueous conductive coating composition. The adhesion promoting resin may be present in the composition in a range of about 10 to 40 weight percent, such as about 15 to 35 weight percent, for example about 20 to 30 weight percent, or any other combination using these extremes, based on the resin component solids content of the one-part aqueous conductive coating composition.

In the one-component aqueous conductive coating composition of the present invention, the weight ratio of the acrylic resin to the tackifier resin may be about 1 to 4 to 1, such as about 1 to 3.

The "polyolefin" resin used in the present invention means a polymer containing an olefin monomer as an essential component. By "substantial amount" is meant that the olefin-based monomers in the polymer constitute at least about 50wt%, for example at least about 60wt%, such as at least about 70wt% of all polymerized monomers.

The polyolefin resin suitable for the present invention in the art may be one or more selected from polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, and acrylonitrile-butadiene-styrene copolymer resin, etc.

Polyolefin resins suitable for use in the present invention in the art are non-halogenated polyolefin resins. The non-halogenated polyolefin resin means a polyolefin resin containing no halogen. For example, polyolefin resins suitable for use in the present invention are non-chlorinated polyolefin resins. The non-chlorinated polyolefin resin means a polyolefin resin containing no chlorine. The polyolefin resin suitable for use in the present invention may also be a maleic acid-modified polyolefin resin.

The polyolefin resins suitable for use in the present invention may be in the form of a dispersion or emulsion having a solids content of 10 to 50wt%, such as 20 to 40wt%. The "solids content" refers to the mass remaining after evaporation as a percentage of the mass of the original dispersion/emulsion.

In the one-component water-based conductive coating, the synergistic cooperation of the high molecular weight acrylic resin and the tackifying resin generates good substrate adhesion, particularly on untreated PP and/or ABS substrates. Therefore, the high molecular weight acrylic resin and the tackifying resin can partially replace polyolefin, so that the one-component waterborne conductive coating disclosed by the invention has the same excellent performance effect as the coating with high polyolefin content in the prior art under the condition of low polyolefin content.

Suitably, the polyolefin resin is present in an amount of no more than 20wt%, such as about 18wt% or less, for example 15wt% or less, based on the solids content of the resin component. For example, the one-part aqueous conductive coating composition according to the present invention may include about 5wt% or more, e.g., about 8wt% or more, such as about 10wt% or more, of the polyolefin resin, and may include about 20wt% or less, such as about 18wt% or less, e.g., about 15wt% or less, of the polyolefin resin, based on the resin component solids amount of the one-part aqueous conductive coating composition. The polyolefin resin may be present in the composition in a range of about 5 to 20 weight percent, such as about 8 to 18 weight percent, for example about 10 to 15 weight percent, or any other combination using these extremes, based on the resin component solids content of the one-part aqueous conductive coating composition.

The resin component in the aqueous one-component conductive coating composition according to the present invention may further include a polyurethane resin. The polyurethane resin refers to a polymer whose repeating unit includes a carbamate-based functional group. The polyurethane may comprise a polymer of at least 50wt% of the organic units, for example at least 70wt%, such as at least 90wt% of the organic units, linked by urethane bonds. Herein, the organic unit comprises one or more residues selected from: simple diols such as butanediol, polyester diols, polyether diols, polycarbonate diols, etc.

Polyurethane resins suitable for use in the present invention may be in the form of a dispersion or emulsion having a solids content of from 20 to 60% by weight, such as from 30 to 50% by weight. The "solids content" refers to the mass remaining after evaporation as a percentage of the mass of the original dispersion/emulsion.

In the waterborne single-component conductive coating composition, the acrylic resin, the polyurethane resin, the rosin resin and the polyolefin resin are compounded, so that an excellent adhesion effect is realized. Specifically, in the aqueous one-component conductive coating composition of the present invention, the ratio of the three of acrylic resin, polyurethane resin, and rosin resin is 1-10.

The aqueous one-component conductive coating composition according to the present invention may include about 20wt% or more, such as about 25wt% or more, for example, about 30wt% or more, of the polyurethane resin, or may include about 50wt% or less, such as about 45wt% or less, for example, about 40wt% or less, of the polyurethane resin, based on the solid amount of the resin component of the aqueous one-component conductive coating composition. The polyurethane resin may be present in the composition in a range of about 20 to 50 weight percent, such as about 25 to 45 weight percent, for example about 30 to 40 weight percent, or any other combination using these extremes, based on the resin component solids content of the one-part aqueous conductive coating composition.

The aqueous one-component conductive coating composition according to the present invention may include a conductive pigment filler. The conductive pigment and filler refers to pigment and/or filler which is subjected to surface treatment and then forms a conductive oxide layer on the surface of the pigment and filler. Conductive pigments and fillers commonly used in the art can be used in the present invention. The conductive pigment and filler suitable for the invention can comprise one or more of conductive titanium white, conductive carbon black, graphene, conductive nanotubes and conductive mica.

The one-part aqueous conductive coating composition according to the present invention may include about 0.1wt% or more, 1wt% or more, 5wt% or more, such as about 10wt% or more, for example about 15wt% or more, of the conductive pigment filler, and/or may include about 35wt% or less, such as about 30wt% or less, for example about 25wt% or less, of the conductive pigment filler, based on the total weight of the one-part aqueous conductive coating composition. The conductive pigment filler may be present in the composition in a range of about 0.1 to 35 weight percent, such as about 1 to 30 weight percent, for example about 5 to 25 weight percent, or any other combination using these extremes, based on the total weight of the one-part, aqueous conductive coating composition.

In the aqueous one-component conductive coating composition of the present invention, the weight ratio of the resin component to the conductive pigment filler may be about 7 to 10, for example, 7.

The aqueous one-component conductive coating composition according to the present invention may further include a non-conductive pigment filler, i.e., a non-conductive pigment and/or a non-conductive filler, depending on the requirements of performance and appearance. Non-conductive pigments suitable for use in the present invention may include organic and/or inorganic pigments such as titanium white, perylene-perylene red, and the like; and/or effect pigments such as aluminum powder, pearl powder, etc. Non-conductive fillers suitable for use in the present invention may include one or more of matting powder, barium sulfate and calcium carbonate. Generally, the aqueous one-component conductive coating composition according to the present invention may include 0 to 40wt% of the non-conductive pigment filler, based on the total weight of the coating composition.

The one-part aqueous conductive coating composition according to the present invention may further include 0 to 10wt% of an organic solvent (may also be referred to as a "co-solvent") based on the total weight of the coating composition. The organic solvent may help compatibilize the ingredients in the composition, thereby affecting the properties of the paint film. The organic solvent suitable for the present invention may include one or more of hydrocarbon solvents, ester solvents, ether solvents, alcohol solvents, and alcohol ether solvents, such as alcohol solvents and/or alcohol ether solvents.

The one-part aqueous conductive coating composition according to the present invention may further include 20 to 40wt% of water based on the total weight of the coating composition.

The aqueous one-component conductive coating composition according to the present invention may further include a substrate wetting agent, a dispersant, and/or a crosslinking assistant, as required for performance and appearance. Substrate wetting agents suitable for use in the present invention may include polyether modified polysiloxane based substrate wetting agents, which may be used in amounts of 0 to 2wt%, such as 0.1 to 2wt%, based on the total weight of the coating composition. Dispersants suitable for use in the present invention may include polyurethane wetting dispersants, which may be used in amounts of 0 to 5wt%, such as 0.1 to 5wt%. Crosslinking aids suitable for use in the present invention may include amino resins, blocked isocyanates or carbodiimides, which may be used in amounts of 0 to 8 weight percent, based on the total weight of the coating composition.

The one-part aqueous conductive coating composition according to the present invention may further include one or more of other auxiliary ingredients including, but not limited to, rheological aids for adjusting the rheological properties of the coating, improving settling resistance upon storage, and sag resistance upon application; a foam inhibitor and a defoaming agent for inhibiting the formation of bubbles and allowing the escape or collapse of generated bubbles during the production process; anti-pinhole agents for increasing the surface tension of the coating and eliminating pinholes; fragrances that provide a pleasant odor to the coating; preservatives that can protect the coating from mold; a pH adjuster for controlling pH and stabilizing the coating; waxes to improve scratch resistance and improve tactile sensation; thickeners to increase the viscosity of the coating and improve the wet film thickness and protect the coating from settling and delamination, and the like. When present, each auxiliary ingredient is present in an amount of up to about 2wt%, based on the total weight of the coating composition.

The aqueous one-component conductive coating composition according to the present invention can be obtained by a preparation method comprising:

(1) Mixing a resin component, a solvent, and optional additives;

(2) Adding matting powder and non-conductive pigment filler into the mixture obtained in the step (1), and dispersing at a high speed of more than 1000rpm for more than 60min to ensure that the fineness of the mixture is more than or equal to 7.0HGM;

(3) And (3) adding conductive pigments and fillers into the mixture obtained in the step (2).

Suitably, the process for preparing the aqueous one-component conductive coating composition according to the present invention is carried out at 10 to 35 ℃.

Suitably, the method for preparing the aqueous one-component conductive coating composition according to the present invention, wherein the step (1) is performed at a rotation speed of 500 to 1000 rpm.

Suitably, the preparation method of the aqueous one-component conductive coating composition according to the present invention, wherein the acrylic resin, the polyurethane resin, the rosin resin, and the polyolefin resin in step (1) are sequentially added into a reactor.

Suitably, the method for preparing an aqueous one-component conductive coating composition according to the present invention, wherein in step (1), water and/or an organic solvent is contained.

Suitably, the method for preparing the aqueous one-component conductive coating composition according to the present invention, wherein the pH of the mixture obtained in step (1) is 8.2 to 8.8.

Suitably, the method for preparing an aqueous one-component conductive coating composition according to the present invention, wherein the non-conductive pigment filler in step (2) is added in the form of an abrasive slurry.

Suitably, the method for preparing an aqueous one-component conductive coating composition according to the present invention, wherein the conductive pigment filler in step (3) is added in the form of an abrasive slurry.

Suitably, the process for the preparation of an aqueous one-component conductive coating composition according to the invention, wherein the pH of the composition system after step (3) is adjusted to 8.2 to 8.8.

The conductive pigment filler and non-conductive pigment filler abrasive slurry can be prepared by conventional methods in the art. The abrasive slurry of the conductive pigment filler and the non-conductive pigment filler suitable for the aqueous one-component conductive coating composition of the present invention can be obtained by a preparation method comprising:

(1) Adding water and optional adjuvants to a vessel;

(2) Adding conductive pigment filler or non-conductive pigment filler while stirring, dispersing, and adding defoaming agent;

in step (1), the optional auxiliary agent is preferably a dispersant and/or a rheological auxiliary agent;

in step (2), a pH adjuster is optionally further added.

The invention also provides a coated substrate, which comprises a substrate and a coating composition coated on the substrate, wherein the coating composition is a one-component water-based conductive coating composition and comprises a resin component and a conductive pigment and filler, wherein the resin component comprises a high-molecular-weight acrylic resin, a tackifying resin and a polyolefin resin, the high-molecular-weight acrylic resin has a weight average molecular weight of more than 75,000, and the content of the polyolefin resin based on the solid content of the resin component is not more than 20wt%.

Suitably, the substrate may be a non-metallic substrate, including a PP and/or ABS substrate. Suitably, the substrate may be a polar substrate, or a non-polar substrate.

According to the coated substrate of the invention, the substrate may not have been treated as follows: surfactant treatment, chemical treatment, flame treatment, UV treatment and/or plasma treatment.

The one-part aqueous conductive coating composition of the present invention can be applied by any standard method known in the art, such as spraying, dipping, rolling, brushing, etc., and then cured under heat to form a coating. Typically, one-part aqueous conductive coating compositions according to the present invention cure at 40-80 ℃ for 5-10 min. The coating layer formed by the coating composition of the present invention may be applied to a thickness of 1 to 20 μm, suitably 5 to 20 μm,1 to 15 μm or 5 to 10 μm.

Examples

The following examples are provided to further illustrate the invention but are not to be construed as limiting the invention to the details set forth in the examples. All parts and percentages in the following examples are by weight unless otherwise indicated.

Example 1:

the single-component water-based conductive coating A1 provided by the invention is prepared by using the components and contents listed in the following table 1, and comprises the following specific steps: (1) Adding acrylic resin, polyurethane resin, rosin resin and polyolefin resin into a reactor in sequence under the condition of stirring; (2) Adjusting the pH value of the mixture in the step (1) to 8.2-8.8, and adding proper deionized water to adjust the viscosity of the system; (3) Stirring and adding a defoaming agent and an organic solvent into the mixture in the step (2); (4) Adding white slurry and matting powder into the mixture obtained in the step (3) by stirring, dispersing the matting powder at a high speed of more than 1000rpm for more than 60min, and detecting the fineness of the mixture to be more than or equal to 7.0HGM, (5) adding conductive black slurry, a base material wetting agent, a defoaming agent and a rheological aid into the mixture obtained in the step (4) by stirring; and (6) adjusting the pH value of the system to 8.2-8.8.

The preparation method of the white pulp comprises the following steps: 1) Adding water, a dispersing agent and a rheological aid into a container in turn under stirring, 2) slowly adding titanium white and a defoaming agent under stirring, dispersing at a high speed for 60 minutes, and then grinding.

The preparation method of the conductive black paste comprises the following steps: 1) adding water and a dispersing agent into a container in sequence under stirring, 2) slowly adding conductive carbon black under stirring, 3) adding a defoaming agent and a pH regulator under stirring after high-speed dispersion is carried out for 60 minutes, continuing high-speed dispersion for 20 minutes, and then grinding.

TABLE 1 one-component aqueous conductive coatings A1-A6 and C1-C4

"\\" indicates that the component was not added; each resin component (wt%) represents a solid content.

a. An amino resin;

b. blocked isocyanates;

c. a carbodiimide;

example 2:

one-component aqueous conductive coating A2 was prepared according to the procedure of example 1

Example 3:

one-part aqueous conductive coating A3 was prepared according to the procedure of example 1

Example 4:

the single-component water-based conductive coating A4 provided by the invention is prepared by using the components and contents listed in the table 1, and the specific steps are as follows: (1) Adding acrylic resin, polyurethane resin, rosin resin and polyolefin resin into a reactor in sequence under the condition of stirring; (2) Adjusting the pH value of the mixture in the step (1) to 8.2-8.8, and adding proper deionized water to adjust the viscosity of the system; (3) Stirring and adding a defoaming agent and an organic solvent into the mixture in the step (2); (4) Adding white slurry and matting powder into the mixture obtained in the step (3) by stirring, dispersing the matting powder at a high speed of more than 1000rpm for more than 60min, and detecting the fineness of the mixture to be more than or equal to 7.0HGM, (5) adding conductive black slurry, amino resin, a base material wetting agent, a defoaming agent and a rheological aid into the mixture obtained in the step (4) by stirring; (6) adjusting the pH value of the system to 8.2-8.8.

Example 5:

the single-component water-based conductive coating A5 provided by the invention is prepared by using the components and contents listed in the table 1, and comprises the following specific steps: (1) Adding acrylic resin, polyurethane resin, rosin resin and polyolefin resin into a reactor in sequence under the condition of stirring; (2) Adjusting the pH value of the mixture in the step (1) to 8.2-8.8, and adding proper deionized water to adjust the viscosity of the system; (3) Stirring and adding a defoaming agent and an organic solvent into the mixture in the step (2); (4) Adding white slurry and matting powder into the mixture obtained in the step (3) by stirring, dispersing the matting powder at a high speed of more than 1000rpm for more than 60min, and detecting the fineness of the mixture to be more than or equal to 7.0HGM, (5) adding conductive black slurry, enclosed isocyanate, a base material wetting agent, a defoaming agent and a rheological aid into the mixture obtained in the step (4) by stirring; (6) adjusting the pH value of the system to 8.2-8.8.

Example 6

The single-component water-based conductive coating A6 provided by the invention is prepared by using the components and contents listed in the table 1, and the specific steps are as follows: (1) Adding acrylic resin, polyurethane resin, rosin resin and polyolefin resin into a reactor in sequence under the stirring condition; (2) Adjusting the pH value of the mixture in the step (1) to 8.2-8.8, and adding proper deionized water to adjust the viscosity of the system; (3) Stirring and adding a defoaming agent and an organic solvent into the mixture in the step (2); (4) Adding white slurry and matting powder into the mixture obtained in the step (3) by stirring, dispersing the matting powder at a high speed of more than 1000rpm for more than 60min, and detecting the fineness of the mixture to be more than or equal to 7.0HGM, (5) adding conductive black slurry, carbodiimide, a base material wetting agent, a defoaming agent and a rheological aid into the mixture obtained in the step (4) by stirring; and (6) adjusting the pH value of the system to 8.2-8.8.

Comparative example C1

A one-component aqueous conductive coating C1 used as a comparative example was prepared using the components and contents listed in table 1, with the specific steps of: (1) Adding polyolefin resin into a reactor, and adding proper deionized water to adjust the viscosity of the system; (2) Stirring and adding a defoaming agent, an organic solvent and white slurry into the mixture in the step (1), adjusting the pH value of the mixture in the step (2) to be 8.2-8.8, (3) stirring and adding matting powder, dispersing the matting powder at a high speed of more than 1000rpm for more than 60min, and detecting the fineness of more than or equal to 7.0HGM, (4) stirring and adding conductive black slurry, a base material wetting agent, a defoaming agent and a rheological aid into the mixture in the step (3); and (5) adjusting the pH value of the system to 8.2-8.8.

Comparative example C2

A one-component aqueous conductive coating C2 used as a comparative example was prepared using the components and contents listed in table 1, with the specific steps of: (1) Sequentially adding polyolefin resin and polyurethane resin into a reactor, and adding proper deionized water to adjust the viscosity of the system; (2) Adding a defoaming agent, an organic solvent and white slurry into the mixture obtained in the step (1) by stirring, adjusting the pH value of the mixture obtained in the step (2) to 8.2-8.8, (3) adding matting powder by stirring, dispersing the matting powder at a high speed for more than 60min at a rotating speed of more than 1000rpm, and detecting the fineness of more than or equal to 7.0HGM, (4) adding conductive black slurry, a base wetting agent, a defoaming agent and a rheological aid into the mixture obtained in the step (3) by stirring; and (5) adjusting the pH value of the system to 8.2-8.8.

Comparative example C3

A one-component aqueous conductive coating C3 used as a comparative example was prepared using the ingredients and contents listed in table 1, with the specific steps: (1) Sequentially adding polyolefin resin, polyurethane resin and acrylic resin into a reactor, and adding proper deionized water to adjust the viscosity of the system; (2) Adding a defoaming agent, an organic solvent and white slurry into the mixture obtained in the step (1) by stirring, adjusting the pH value of the mixture obtained in the step (2) to 8.2-8.8, (3) adding matting powder by stirring, dispersing the matting powder at a high speed for more than 60min at a rotating speed of more than 1000rpm, and detecting the fineness of more than or equal to 7.0HGM, (4) adding conductive black slurry, a base wetting agent, a defoaming agent and a rheological aid into the mixture obtained in the step (3) by stirring; and (5) adjusting the pH value of the system to 8.2-8.8.

Comparative example C4

The specific procedure for preparing the one-part aqueous conductive coating C4 used as a comparative example using the ingredients and contents listed in table 1 was: (1) Sequentially adding polyolefin resin, polyurethane resin and rosin resin into a reactor, and adding proper deionized water to adjust the viscosity of the system; (2) Stirring and adding a defoaming agent, an organic solvent and white slurry into the mixture in the step (1), adjusting the pH value of the mixture in the step (2) to be 8.2-8.8, (3) stirring and adding matting powder, dispersing the matting powder at a high speed of more than 1000rpm for more than 60min, and detecting the fineness of more than or equal to 7.0HGM, (4) stirring and adding conductive black slurry, a base material wetting agent, a defoaming agent and a rheological aid into the mixture in the step (3); and (5) adjusting the pH value of the system to 8.2-8.8.

And (4) performance testing:

firstly, coating the single-component waterborne conductive coatings A1, A2, A3, A4, A5 and A6 provided by the invention and the single-component waterborne conductive coatings C1, C2, C3 and C4 of the comparative example on an untreated PP or ABS substrate, and curing at 40-80 ℃ for 5-10 min; then coating water-based colored paint and curing at 40-80 ℃ for 5-10 min, and solvent-based varnish and curing at 80-90 ℃ for 30-50 min, and finally standing at room temperature for 7 days.

The coated substrate described above was subjected to the following performance tests:

adhesion properties: the adhesion properties of the coatings were evaluated with reference to the GMW14829-2017A standard. The method comprises the following steps: the adhesive force is 0-1 grade.

Base material

A1

A2

A3

A4

A5

A6

C1

C2

C3

C4

PP

OK

NG

OK

NG

ABS

OK

NG

Adhesion properties under severe conditions:

steam injection：

Standard of merit	PV1503
		Device	Walter
Marking off	60 degree X-shaped cross line
		Cutting tool	knife
Temperature of water	70℃
		Injection pressure	90±5bar
Water flow rate	10.5L/min
		Angle of impact	45°
Distance of impact	150mm
		Time of impact	20s per cut
Nozzle requirements	EG 2505
		Impact mode	Spraying along the lines, one time per line
Require to make a request for	No film delamination at the scribe

Soaking in water: soaking in 40-degree water for 240h continuously, and testing standard reference GBT1733 by the following specific method:

adding a sufficient amount of deionized water into a water tank, adjusting the water temperature to 40 +/-1 ℃, keeping the temperature in the whole test process, then starting circulation and ventilation of water in the tank, placing samples on a test plate frame, soaking 2/3 of the samples in the water, keeping the distance between the samples at least 30mm and the distance between the samples and the tank bottom and the tank wall at least 50mm, continuously changing the positions of the samples in the tank during the test, wherein the changing time interval does not exceed 3d, taking the samples out of the tank after reaching the set time of 240h, checking the phenomena of light loss, color change, foaming and the like on the surfaces of the samples after absorbing water stains by using filter paper and recovering for 24h, and testing the adhesive force condition to evaluate the water resistance of the paint film. And (3) test results: the appearance should have no defects such as light loss, color change, bubbling, wrinkling and the like, and the adhesive force is 0-1 grade.

Oil immersion: soaking in E92# gasoline for half an hour, and the specific method is as follows:

adding sufficient gasoline into a glass groove, inserting a sample into the groove, soaking 2/3 of the length of a test plate in No. 92 gasoline, taking out the sample when the specified time is reached, wiping the surface by using filter paper to remove residual liquid on the surface, recovering for 24h, observing the phenomena of light loss, color change, foaming and the like on the surface of a paint film, testing the adhesive force, and evaluating the gasoline resistance of the paint film. And (3) test results: the appearance should have no defects such as light loss, color change, bubbling and the like, and the adhesive force is 0-1 grade.

Steam injection under severe conditions

Base material

A1

A2

A3

A4

A5

A6

C1

C2

C3

C4

PP

OK

NG

ABS

OK

NG

OK

NG

Water resistance under severe conditions

Base material

A1

A2

A3

A4

A5

A6

C1

C2

C3

C4

PP

OK

NG

ABS

OK

NG

E92# gasoline resistant under severe conditions

Base material

A1

A2

A3

A4

A5

A6

C1

C2

C3

C4

PP

OK

NG

Other Performance tests

* The recoating refers to coating the base paint, the colored paint and the varnish on the substrate, and then coating the base paint, the colored paint and the varnish again, wherein the base paint is the one-component waterborne conductive coating according to the invention.

According to the performance test results, the single-component water-based conductive coating provided by the invention has remarkably excellent steam spraying performance, namely the steam spraying can pass the PV1503 standard; the waterproof paint has remarkable excellent waterproof performance, namely after being continuously soaked in 40-degree water for 240 hours, the paint is taken out and recovered for 24 hours, the surface of a test sample is inspected to have no phenomena of light loss, color change, foaming and the like, and the test adhesive force is 0-1 grade; the test sample has excellent gasoline resistance, namely the test sample is soaked in E92# gasoline for half an hour, taken out and recovered for 24 hours, the surface of the test sample is inspected to have no phenomena of light loss, color change, foaming and the like, and the test adhesive force is 0-1 grade. In addition, the single-component water-based conductive coating provided by the invention also meets the performance requirements of the primer for the automobile parts, such as cold-wet circulation, accelerated aging resistance, impact resistance, recoating and the like.

Therefore, it can be seen from the above performance test results that the adhesion of the coating to a substrate, especially to an ABS substrate, is improved while further reducing the cost by replacing a portion of the polyolefin resin with the acrylic resin, the polyurethane polyester, and the tackifying resin. Even under severe conditions, such as steam injection, water immersion and oil immersion, the single-component water-based conductive coating provided by the invention still has excellent adhesion and combines excellent water resistance, oil resistance and adhesion.

While particular aspects of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A one-part aqueous conductive coating composition comprising a resin component and a conductive pigment filler, wherein the resin component comprises a high molecular weight acrylic resin, a tackifying resin, and a polyolefin resin, the high molecular weight acrylic resin having a weight average molecular weight of greater than 75,000, and the polyolefin resin being present in an amount of no more than 20wt% based on the solids content of the resin component.

2. The coating composition of claim 1, wherein the composition is thermoplastic.

3. A coating composition according to claim 2 or 3, wherein the weight ratio of high molecular weight acrylic resin to tackifying resin is from 4.

4. The coating composition of any one of claims 1-3, wherein the high molecular weight acrylic resin has a weight average molecular weight greater than 100,000.

5. The coating composition of any one of claims 1-4, wherein the high molecular weight acrylic resin has a glass transition temperature of less than 0 ℃.

6. The coating composition according to any one of claims 1 to 5, wherein the high molecular weight acrylic resin has an acid value of not more than 10 mgKOH/g.

7. The coating composition of any one of claims 1-6, wherein the high molecular weight acrylic resin comprises at least 70wt% of (meth) acrylic monomers based on its solids weight.

8. The coating composition of any one of claims 1-7, wherein the adhesion-promoting resin comprises a rosin resin and/or a terpene-based resin.

9. The coating composition of any one of claims 1-8, wherein the tackifying resin has a weight average molecular weight of less than 1,000.

10. The coating composition of claim 8 or 9, wherein the adhesion-promoting resin has a softening point of less than 100 ℃.

11. The coating composition of any one of claims 8-10, wherein the tackifying resin has an acid value of no more than 10 mgKOH/g.

12. The coating composition of any one of claims 1-11, wherein the resin component further comprises a polyurethane resin.

13. The coating composition of any one of claims 1-12, wherein the weight ratio of the resin component to electrically conductive pigment filler is from 7 to 10.

14. The coating composition of any one of claims 1-13, wherein the coating composition has a solids content of 30% to 35%.

15. The coating composition of any one of claims 1-14, wherein the coating composition forms a coating layer having an electrical resistance of less than 500K Ω after dehydration at 80 ℃ for 5 min.

16. The coating composition of any one of claims 1-15, wherein the coating composition forms a coating with adhesion on untreated PP/ABS of at least 0 to 1 grade, with reference to GMW14829-2017A standard.

17. A coated substrate comprising a substrate and the coating composition of any one of claims 1-16 coated on at least a portion of the substrate.

18. The coated substrate of claim 17, wherein the substrate comprises a non-metallic substrate.

19. A coated substrate according to claim 17 or 18, wherein the substrate comprises PP and/or ABS.

20. The coated substrate of any one of claims 17-19, wherein the substrate comprises a polar substrate and/or a non-polar substrate.

21. The coated substrate of any one of claims 17-20, wherein the substrate is free of surfactant treatment, chemical treatment, flame treatment, UV treatment, and/or plasma treatment.