Production method of magnetic pearlescent effect pigment

Abstract

The invention relates to the technical field of pigment production, and provides a production method of a magnetic pearlescent effect pigment, which comprises the following steps: 1, preparing a base material; forming an original magnetic base material by coating the surface of the support body with a coating containing a magnetic material; and step 2, chemical coating. The prepared pigment base material is subjected to chemical coating treatment, so that a pearlescent coating layer is formed on the surface of the base material, and the base material is endowed with pearlescent luster; and step 3, post-processing. And carrying out post-treatment on the base material subjected to chemical coating to finally prepare the magnetic pearlescent effect pigment with high gloss, high magnetic conductivity and stable batch. According to the preparation method of the magnetic pearlescent pigment provided by the invention, a uniform base material is obtained through controllable coating, demolding and grading screening, and then high gloss, high magnetic conductivity and batch stability are realized through chemical coating and post-treatment, so that the problem that magnetism and gloss are difficult to consider at the same time in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pigment production, in particular to a production method of magnetic pearl effect pigment. BACKGROUND

[0002] Magnetic pearl effect pigment is a kind of functional pigment with magnetic guiding characteristics. It can be arranged in the direction of the magnetic field under the action of an external magnetic field, thereby forming a unique pattern and stereoscopic visual effect, and has a wide application prospect in the fields of coatings, inks, cosmetics, etc. At present, this kind of pigment is mainly prepared by two process routes: vacuum coating and wet chemical coating. Among them, the vacuum coating method obtains a magnetic layer by depositing a magnetic material on the surface of the substrate, but its production cost is high and the efficiency is low, especially when using a single cavity coating equipment, the unit production is small, the color consistency between batches is poor, and it is difficult to realize large-scale stable production.

[0003] On the other hand, the wet chemical coating method coats a magnetic material such as iron oxide on the surface of the pearl effect pigment flake through an aqueous solution reaction. However, since iron oxide itself has strong hiding power, when the coating amount is too high, it will cover the pearl luster, resulting in a black final product, losing the pearl effect; and if the coating amount of the magnetic material is reduced, the magnetic permeability will be insufficient. In addition, this method usually uses natural mica, synthetic mica, flaky aluminum oxide, glass flake, etc. as the substrate, and these materials generally have problems such as uneven surface or large specific gravity, which affect the optical performance and magnetic field responsiveness. The existing related patents (such as CN200810162941.X, CN201510340610.0, CN201610354586.0, CN201810840233.0, CN202110830795.9, CN201220523519.4, etc.) mainly focus on introducing magnetic materials on the surface of pearl pigment flake, and cannot fundamentally solve the contradiction between magnetic permeability and pearl luster.

[0004] CN200810039976.4 discloses a preparation method of laser pigment, which involves a coating process, but does not realize the technical path of first obtaining a magnetic substrate and then constructing a pearl structure. A coating and iron plating method for high-light pearl magnetic powder disclosed by Guangdong Bocai Yahuangong Technology Co., Ltd. (application number: CN202510041000) uses a combination of vacuum coating and wet coating to load magnetic materials, although the magnetic properties are improved, the process is complex and the cost is high, and there is still a problem of the magnetic layer covering the pearl color. Therefore, it is urgent to develop a new production process that can ensure excellent pearl luster while significantly improving the magnetic permeability, batch stability and color performance of the magnetic pearl effect pigment. SUMMARY

[0005] The purpose of the present application is to solve the problems of the existing magnetic pearl effect pigment, such as difficult to balance between magnetism and pearl gloss, substrate performance limiting optical expression, complex process and poor batch stability, and the present application adopts the following technical scheme:

[0006] A production method of a magnetic pearl effect pigment, comprising the following steps:

[0007] Step one: substrate preparation. Forming a raw magnetic substrate by coating a coating layer containing magnetic material on the surface of a support; separating the raw magnetic substrate from the support and obtaining a pigment substrate with a flat surface, uniform thickness and regular shape through a grading screening process;

[0008] Step two: chemical coating. Performing chemical coating treatment on the prepared pigment substrate to form a pearl coating layer on the surface of the substrate and give the substrate a pearl gloss;

[0009] Step three: post-treatment step. Post-treating the substrate after chemical coating to finally obtain a magnetic pearl effect pigment with high gloss, high magnetic permeability and batch stability.

[0010] The production method of a magnetic pearl effect pigment as described above, the support is a film material, the coating layer is coated on the film material through a film material coating process to form a raw magnetic substrate, and the coating layer is a release layer and a magnetic substrate layer.

[0011] The production method of a magnetic pearl effect pigment as described above, the film material can be selected from one of a pet film, a fluorocarbon film, a nylon film and a metal film.

[0012] The production method of a magnetic pearl effect pigment as described above, the coating layer comprises a release layer and a magnetic substrate layer arranged in sequence, wherein the release layer is formed by coating a release agent on the surface of the film material, the release agent is selected from one or more combinations of a silicon-based release agent, a resin-based release agent or a salt solution-based release agent, and the release layer is used to realize controllable separation between the subsequent magnetic substrate layer and the film material, thereby facilitating the smooth progress of the film removal process.

[0013] The production method of a magnetic pearl effect pigment as described above, the magnetic substrate layer is composed of a metal oxide with magnetic permeability, and the metal oxide is selected from one or more of iron oxide, ferrous oxide and cobalt oxide, and the magnetic substrate layer is formed by hydrolysis and condensation reaction of soluble salt of the above metal in aqueous solution, and the generated metal oxide or hydroxide is deposited on the surface of the release layer to form a dense coating layer.

[0014] The production method of a magnetic pearl effect pigment as described above, the coating process is selected from one of gravure coating, microgravure coating, blade coating, spraying, extrusion coating, stamping and pressure coating.

[0015] The production method of the magnetic pearl effect pigment as described above, wherein the film separating process is selected from one of solution elution, air flow film separation and blade coating film separation, and is used to separate the magnetic substrate layer from the film material surface.

[0016] The production method of the magnetic pearl effect pigment as described above, wherein the grading screening process is selected from one of air flow grading, centrifugal sedimentation, screening grading and mold grading.

[0017] The production method of the magnetic pearl effect pigment as described above, wherein the chemical coating process to obtain the pearl luster is to perform a deposition treatment of the pearl material on the surface of the magnetic substrate sheet, so as to obtain a multi-layer structure with optical interference effect, thereby presenting the pearl luster.

[0018] The titanium dioxide (TiO2) pearl layer is prepared by using titanium tetrachloride (TiCl4) hydrolysis deposition method, and the main reaction process is as follows:

[0019] TiCl4+4H2O→Ti(OH)4+4HCl

[0020] Subsequently, the generated titanium hydroxide (Ti(OH)4) is bonded with the silicon-oxygen-iron (Si–O–Fe) structure on the surface of the magnetic substrate under the control of pH conditions:

[0021] Ti(OH)4+Si–O–Fe→Ti(OH)4–Si–O–Fe→calcined TiO2–Si–O–Fe

[0022] Through the calcination treatment, the titanium hydroxide is dehydrated and converted into the titanium dioxide layer with an anatase type or rutile type structure, and finally the composite structure magnetic pearl pigment with excellent pearl effect is formed.

[0023] Through the calcination treatment, the titanium hydroxide is dehydrated and converted into the titanium dioxide layer with an anatase type or rutile type structure, and finally the composite structure magnetic pearl pigment with excellent pearl effect is formed.

[0024] The production method of the magnetic pearl effect pigment as described above, wherein the post-treatment step of the pigment includes surface wetting, dispersion treatment, weather resistance improvement treatment and brightening treatment.

[0025] The production method of the magnetic pearl effect pigment as described above, wherein the brightening post-treatment refers to forming a metal coating layer on the surface of the pigment sheet by using the electrochemical deposition method, so as to improve the transparency and luster performance; specifically, the depositable metal ion solution is added in the aqueous phase system after the preparation of the pigment, and the metal ions are reduced to metal atoms on the surface of the pigment sheet by applying current and forming a uniform and dense metal deposition layer, so as to enhance the optical reflection performance and visual brightness of the pigment.

[0026] The embodiment of the present application has the following beneficial effects:

[0027] 1. In the present application, by coating the surface of the support with magnetic material and performing controllable demolding and grading screening, flat, uniform thickness, and regular shape magnetic base material particles are obtained, thereby providing an excellent foundation for the uniform deposition of the subsequent pearl layer; then by chemical coating, a pearl layer with optical interference effect is formed, so that the pigment has excellent pearl luster and magnetic responsiveness; finally, by optimizing the post-treatment process, the gloss, magnetic permeability, and batch stability of the product are significantly improved. The method has controllable process and good repeatability, effectively solving the problems of existing magnetic pearl pigments, such as difficult to balance magnetism and gloss, limited optical expression, complex process, and batch instability. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 is a structural schematic diagram of a magnetic pearl effect pigment of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] As shown in Figure 1 , the present application proposes a production method of a magnetic pearl effect pigment, which refers to a pigment with a certain thickness-diameter ratio, flaky structure, pearl luster, and magnetic permeability, which can be arranged along the direction of the magnetic field, including the following steps:

[0032] Step one: base material preparation. By coating the surface of the support with a coating layer containing magnetic material, an original magnetic base material is formed; the original magnetic base material is separated from the support, and by grading screening process, a pigment base material with flat surface, uniform thickness, and regular shape is obtained.

[0033] The support is a film material, and the film material is coated by a coating process selected from one of gravure coating, microgravure coating, blade coating, spray coating, and extrusion coating, stamping, and pressure coating, preferably microgravure coating.

[0034] The release layer is formed by coating a release agent on the surface of the film material, and the release agent is selected from one or more combinations of silicon-based release agents, resin-based release agents, or salt solution-based release agents. The release layer is used to achieve controllable separation between the subsequent magnetic substrate layer and the film material, thereby facilitating the smooth progress of the film stripping process. Preferably, a resin release agent is selected, which can be effectively stripped by solution elution during the film stripping process. And using a photoetching square process to achieve more sharpening film stripping. Among them, the silicon release agent in the release agent is an organic silicon release agent, the resin release agent is a resin solution of epoxy resin, acrylic acid resin, cellulose resin, etc., the salt solution release agent is a halogen solution, in order to facilitate elution, environmental protection, and adopt photoetching square film stripping process, preferably select Isman 381-0.5CAB resin, and the photoetching mother film resin uses Nanning Huashide UV100.

[0035] The film stripping process is selected from one of solution elution, air flow film stripping, and blade coating film stripping, which is used to separate the magnetic substrate layer from the surface of the film material. Preferably, solvent elution is selected.

[0036] The magnetic substrate layer is composed of metal oxides with magnetic properties, and the metal oxides are selected from one or more of iron oxide, ferrous oxide, and cobalt oxide. The magnetic substrate layer is formed by hydrolysis and condensation reaction of soluble salt of the above metal in aqueous solution, and the generated metal oxide or hydroxide is deposited on the surface of the release layer to form a dense coating. Preferably, silicon sol and ferric chloride are used to generate acid-base reaction and condensation reaction to form a dense and stable magnetic substrate, and finally obtain a silicon-iron substrate. The reaction equation is as follows:

[0037] FeCl3·6H2O + NaOH → Fe(OH)3(colloid) + 3HCl

[0038] Si-OH + HO-Fe → Si-O-Fe + H2O (reaction with rare metal as catalyst and heating)

[0039] The film material can be selected from one of pet film, fluorocarbon film, nylon film, and metal film, preferably nylon film. The surface of the nylon film has a stable daoyin value surface energy, which can easily realize coating. The thickness of the film material is 8-3000 microns, preferably 70 microns of nylon film PA12,1200mm wide produced by Enxin.

[0040] The classification process is selected from one of air classification, centrifugal settling, sieve classification and die classification. Preferably, die classification is selected, which is a relatively new method for preparing pigment flakes. A grid-like structure layer is provided on the base film, and the coating is separated along the structural texture direction during the film removal process, thereby achieving the classification of grid-shaped pigment flakes. The particle size of the classified grid-shaped pigment base film is 10 microns. The base film obtained by elution is washed several times to remove the salt of the release agent, thereby facilitating the subsequent coating and encapsulation.

[0041] Step two: chemical coating. The prepared pigment base material is subjected to chemical coating treatment to form a pearlescent coating layer on the surface of the base material, thereby imparting pearlescent luster to the base material.

[0042] The process of obtaining pearlescent luster by chemical coating is to deposit a pearlescent material on the surface of the magnetic base film to obtain a multilayer structure with optical interference effect, thereby presenting pearlescent luster. Titanium tetrachloride (TiCl4) hydrolysis deposition method is used to prepare titanium dioxide (TiO2) pearlescent layer, and the main reaction process is as follows:

[0043] Ti Cl4+4H2O→Ti Cl4+4HCl

[0044] Subsequently, the generated titanium hydroxide (Ti(OH)4) undergoes a bonding reaction with the silicon-oxygen-iron (Si–O–Fe) structure on the surface of the magnetic base material under controlled pH conditions:

[0045] Ti(OH)4+Si–O–Fe→Ti(OH)4–Si–O–Fe→calcined TiO2–Si–O–Fe

[0046] Through calcination treatment, titanium hydroxide is dehydrated and converted into a titanium dioxide layer with anatase or rutile structure, and finally a composite structure magnetic pearlescent pigment with excellent pearlescent effect is formed.

[0047] Different pigment flakes with pearlescent effect are prepared by hydrolysis deposition mechanism.

[0048] Step three: post-treatment step. The base material after chemical coating is subjected to post-treatment, and finally a magnetic pearlescent effect pigment with high gloss, high magnetic permeability and batch stability is obtained.

[0049] The post-treatment step of the pigment includes surface wetting, dispersion treatment, weather resistance improvement treatment and brightening treatment.

[0050] The post-treatment of brightening refers to forming a metal coating layer on the surface of the pigment sheet by electrochemical deposition to improve its transparency and gloss performance; specifically, adding a depositable metal ion solution in an aqueous system after the preparation of the pigment, and reducing the metal ions to metal atoms on the surface of the pigment sheet by applying current to form a uniform and dense metal deposition layer, thereby enhancing the optical reflection performance and visual brightness of the pigment.

[0051] The method can obtain a very smooth, uniform thickness, and regular magnetic substrate in the preparation stage of the front substrate, and finally produce a magnetic pearlescent pigment with high gloss, high magnetic permeability, and batch stability.

[0052] Example 1:

[0053] In this embodiment, a high-gloss magnetic pearlescent pigment based on a silicon-iron substrate is prepared. The specific steps are as follows:

[0054] Step 1: Substrate preparation

[0055] A 70-micron-thick nylon film PA12 produced by Enxingge Company is selected as the support, with a width of 1200 mm and a surface dyne value stabilized at about 42 mN / m, which is conducive to uniform adhesion of the coating layer. The film is demolded by UV light etching square demolding process combined with solvent elution method.

[0056] First, the UV100 mother film glue of Nanning Huashuide is coated on the nylon film and ultraviolet light is exposed to form a regular square texture on the release layer, with a square size of 10 μm*10 μm. Then, a release layer composed of Eusmann 381-0.5 CAB resin is coated on it by micro-concave coating method, with a thickness of 1-2 μm. Subsequently, the same micro-concave coating process is used to coat a mixed solution containing ferric chloride (FeCl3·6H2O) and silica sol, and a small amount of palladium salt is added as a catalyst. The hydrolysis and condensation reaction is carried out at 80°C to generate a dense magnetic substrate layer with Si–O–Fe structure, with a thickness of about 500 nm.

[0057] Then, the magnetic substrate is peeled off from the nylon film with ethyl acetate / water mixed solvent. Square substrate particles with a particle size of about 10 microns are obtained. After washing with deionized water for several times, the residual CAB resin and reaction byproducts such as NaCl and HCl are removed to obtain pure silicon-iron substrate particles.

[0058] Step 2: Chemical coating

[0059] The above cleaned silicon-iron substrate particles are dispersed in deionized water, and titanium tetrachloride (TiCl4) solution is slowly added dropwise. Under stirring conditions, the pH is adjusted to 2.5-3.0 to make TiCl4 hydrolyze to form Ti(OH)4 colloid and deposit on the Si–O–Fe structure on the surface of the substrate.

[0060] Subsequently, the sample is heated to 120°C for 2 hours, and then calcined at 500°C for 3 hours to dehydrate the titanium hydroxide and convert it into a titanium dioxide (TiO2) layer with a rutile structure, forming a pearl coating layer with an optical interference effect

[0061] Step three: post-treatment

[0062] Electrochemical deposition is used for brightening treatment: silver nitrate solution is added to the aqueous system, and direct current is applied to reduce and deposit silver ions on the surface of the pigment as a dense metal silver layer, significantly improving its gloss and reflection performance.

[0063] Electrochemical deposition method: Ag + + e - → Ag (metallic silver deposition)

[0064] Direct current is applied to the electrode plates at both ends of the reaction cell, and silver nitrate and magnetic pearl sheets are added to the cell in a molar ratio. The generated silver is deposited on the surface of the magnetic pearl sheets while stirring, increasing their gloss.

[0065] The pearl-coated pigment particles are further subjected to surface wetting and dispersion treatment to improve their compatibility in subsequent application media.

[0066] The silane coupling agent KH560 is preferably selected (its structural formula is RSiX3, R is an epoxy group, and X is a methoxy group—OCH3). The methoxy group (—OCH3) hydrolyzes to form silanol (Si—OH), which then binds with the magnetic effect pigment sheet to form a firm combination. The epoxy group in the silane coupling agent is useful for wetting and dispersion

[0067] Finally, after drying and screening, the finished magnetic pearl effect pigment is obtained.

[0068] The obtained pigment has excellent pearl gloss, high magnetic permeability (saturation magnetization ≥ 50 emu / g), and good batch stability, and is suitable for use in high-end coatings, inks, and cosmetics.

[0069] Example two:

[0070] In this example, a weather-resistant magnetic pearl effect pigment based on a cobalt-silicon composite substrate is prepared. The specific steps are as follows:

[0071] Step one: substrate preparation

[0072] PET film is selected as the support body, with a thickness of 12 μm. A composite release layer composed of epoxy resin and silicon-based release agent is coated on the PET film by doctor blade coating process, with a thickness of 2-3 μm, for controlled demolding.

[0073] Subsequently, a mixed solution containing cobalt oxide precursor (Co(NO3)2·6H2O) and silica sol was coated on the release layer by doctor blade method, and hydrolysis and condensation reaction was carried out at 60°C to form a magnetic substrate layer with Co-O-Si structure, with a thickness of about 400 nm.

[0074] After the coating was dried, the magnetic substrate was peeled off from the PET film by air flow demolding method. Then, the substrate particles were classified by centrifugal sedimentation method to obtain substrate particles with an average particle size of 15 microns, and washed with water several times to remove residual release agent.

[0075] Step two: chemical coating

[0076] The washed magnetic substrate particles were dispersed in deionized water, and a mixed solution of tetraethyl orthosilicate (TEOS) and titanium tetrachloride (TiCl4) was added to carry out co-hydrolysis reaction under acidic conditions to form a TiO2 / SiO2 composite pearl layer.

[0077] The reaction temperature was controlled at 80°C, and the pH was maintained between 3.0 and 3.5. After the reaction was completed, the sample was dried at 100°C and calcined at 500°C to form a stable anatase structure of the composite coating layer, enhancing the optical interference effect and weather resistance.

[0078] Step three: post-treatment

[0079] The coated pigment particles were treated to improve weather resistance, and silane coupling agent KH-550 was used for surface modification to improve their dispersibility and stability in organic media.

[0080] Subsequently, brightening treatment was carried out, and copper metal layer was deposited on the surface of the pigment by electrochemical deposition method to further enhance its visual brightness and metallic feel.

[0081] Finally, after drying and screening, the finished magnetic pearl effect pigment was obtained.

[0082] The obtained pigment has good magnetic response (saturation magnetization ≥ 35 emu / g), excellent pearl luster and excellent weather resistance.

[0083] Example three: preparation of environmentally friendly magnetic pearl pigment based on ferrous oxide-silicon composite system. The specific steps are as follows:

[0084] Step one: substrate preparation

[0085] A fluorocarbon film with a thickness of 12 microns was selected as the support, and a composite release layer composed of acrylic resin and silicon release agent was coated on its surface by spraying method, with a thickness of about 2 microns, to achieve good demolding performance and environmental friendliness.

[0086] Subsequently, a mixed solution containing ferrous sulfate (FeS04·7H20) and silica sol is coated on the release layer by doctor blade method, a small amount of cobalt salt is added as catalyst, and hydrolysis and condensation reaction is carried out at 60°C to generate a magnetic substrate layer with Fe-O-Si structure, with a thickness of about 60 nm.

[0087] After the coating is dried and cured, the magnetic substrate is peeled off from the fluorocarbon film by air flow demolding + solution elution combined demolding process. Then the substrate particles after demolding are screened by screening classification method to obtain regular substrate particles with an average particle size of 12 microns, and multiple water washing is performed to remove residual release agent and reaction byproducts.

[0088] Step two: chemical coating

[0089] The above cleaned magnetic substrate particles are dispersed in deionized water, titanium tetrachloride (TiCl4) solution is added, and the pH is adjusted to 2.8-3.2 under stirring conditions to make TiCl4 hydrolyze to generate Ti(OH)4 colloid and deposit on the Fe-O-Si structure on the surface of the substrate.

[0090] Subsequently, the sample is heated to 100°C for 2 hours, and then calcined at 450°C for 3 hours to dehydrate the titanium hydroxide into a titanium dioxide layer with anatase structure, forming a pearl luster coating layer with optical interference effect.

[0091] Step three: post-treatment

[0092] The pigment particles after pearl luster coating are subjected to surface wetting and dispersion treatment, and are surface modified by silane coupling agent KH-570 to improve their compatibility and dispersibility in the coating system.

[0093] Further brightening treatment is carried out by electrochemical deposition method: silver nitrate solution is added in the aqueous system, and direct current is applied to reduce and deposit silver ions on the surface of the pigment into a dense metal silver layer, significantly enhancing its visual brightness and metallic feel.

[0094] Finally, after drying and screening treatment, the finished magnetic pearl luster effect pigment is obtained.

[0095] The obtained pigment has good magnetic conductivity (saturation magnetization ≥ 30 emu / g), excellent pearl luster and good environmental performance.

[0096] Example four: preparation of multifunctional magnetic pearl luster pigment based on multi-metal oxide composite system. The specific steps are as follows:

[0097] Step one: substrate preparation

[0098] A 100-μm-thick aluminum foil was selected as the support, and a UV1000 metal mother film glue produced by Nanning Huaiwei Company was imprinted on the surface thereof and subjected to ultraviolet exposure to form a regular grid texture for the release layer, with a grid specification of 10 μm*10 μm. Then, an extrusion coating method was used to coat a composite release layer composed of a cellulose resin and a halogen salt solution, with a thickness of about 3 μm, to facilitate subsequent efficient demolding.

[0099] Subsequently, a mixed solution containing ferric chloride (FeCl3·6H2O), cobalt nitrate (Co(NO3)2·6H2O), and silica sol was coated on the release layer by gravure coating, and a platinum salt was added as a catalyst. A co-hydrolysis condensation reaction was performed at 90°C to generate a Fe / Co–O–Si composite structure magnetic base material layer with a thickness of about 400 nm.

[0100] Subsequently, the magnetic base material was peeled off from the aluminum foil film using an ethyl acetate / water mixed solvent. Square base material particles with a particle size of about 10 microns were obtained. After being washed with deionized water for multiple times, the residual cellulose resin and reaction byproducts were removed to obtain pure silicon-iron base material particles.

[0101] Step two: chemical coating

[0102] The above-mentioned washed composite base material particles were dispersed in deionized water, and a mixed solution of tetraethyl orthosilicate (TEOS) and zirconium tetrachloride (ZrCl4) was added. A co-hydrolysis reaction was performed under acidic conditions to generate a TiO2 / SiO2 / ZrO2 composite pearl layer.

[0103] The reaction temperature was controlled at 80°C, and the pH was maintained between 3.0 and 3.5. After the reaction was completed, the sample was dried at 100°C and calcined at 600°C to form a stable rutile structure for the composite coating layer, thereby enhancing the optical interference effect and high-temperature resistance.

[0104] Step three: post-treatment

[0105] The coated pigment particles were subjected to weather resistance improvement treatment, and a silane coupling agent KH-560 was used for surface modification to improve their dispersibility and stability in organic media.

[0106] Subsequently, a brightening treatment was performed, and an electrochemical deposition method was used to deposit a silver-nickel alloy layer on the surface of the pigment to further enhance its visual brightness and corrosion resistance.

[0107] Finally, after drying and screening, the finished magnetic pearl effect pigment was obtained.

[0108] The obtained pigment has excellent magnetic response (saturation magnetization ≥55 emu / g), high gloss, and good thermal stability and weather resistance.

[0109] In summary, the present application solves the problem that the existing magnetic pearl effect pigment is difficult to balance between magnetism and pearl gloss, the performance of the base material limits optical expression, the process is complex, and the batch stability is poor.

[0110] It should be understood that the terms "first", "second" and the like are adopted in the present application to describe various information, but these information should not be limited to these terms, and these terms are only used to distinguish the same type of information from each other. For example, the "first" information can also be referred to as "second" information without departing from the scope of the present application, and similarly, the "second" information can also be referred to as "first" information. In addition, the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0111] The above is the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A method for producing a magnetic pearlescent pigment, characterized in that, Includes the following steps: Step 1: Substrate preparation. A raw magnetic substrate is formed by coating the surface of the support with a coating containing magnetic material; the raw magnetic substrate is separated from the support and a pigment substrate with a flat surface, uniform thickness and regular shape is obtained by a graded screening process; Step 2: Chemical Coating. The pigment substrate obtained above is subjected to chemical coating treatment to form a pearlescent coating layer on the substrate surface, giving the substrate a pearlescent luster; Step 3: Post-processing. The chemically coated substrate undergoes post-processing to ultimately obtain a high-gloss, highly magnetically permeable, and batch-stable magnetic pearlescent pigment.

2. The method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The support is a membrane material. A coating is applied to the membrane material through a coating process to form an original magnetic substrate. The coating consists of a release layer and a magnetic substrate layer.

3. The method for producing a magnetic pearlescent pigment according to claim 2, characterized in that, The membrane material can be selected from one of the following: PET film, fluorocarbon film, nylon film, or aluminum foil.

4. The method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The coating comprises a release layer and a magnetic substrate layer arranged sequentially. The release layer is formed by coating a release agent onto the surface of the film material. The release agent is selected from one or more combinations of silicone-based release agents, resin-based release agents, or salt solution-based release agents. The release layer is used to achieve controllable separation between the subsequent magnetic substrate layer and the film material, thereby facilitating the smooth progress of the demolding process.

5. The method for producing a magnetic pearlescent pigment according to claim 2, characterized in that, The magnetic substrate layer is composed of a metal oxide with magnetic conductivity. The metal oxide is selected from one or more of iron oxide, ferrous oxide, and cobalt oxide. The magnetic substrate layer is formed by hydrolyzing and condensing the soluble salts of the above metals in an aqueous solution, so that the generated metal oxides or hydroxides are deposited on the surface of the release layer to form a dense coating.

6. The method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The coating process is selected from one of gravure coating, microgravure coating, scraping coating, spraying and extrusion coating, embossing, and die coating.

7. The method for producing a magnetic pearlescent pigment according to claim 4, characterized in that, The stripping process is selected from one of solution elution, airflow stripping, and scraping stripping, and is used to separate the magnetic substrate layer from the surface of the film.

8. The method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The grading and screening process is selected from one of air classification, centrifugal sedimentation, sieving and grading and mold classification.

9. The method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The process of achieving pearlescent luster through chemical coating involves depositing pearlescent materials on the surface of a magnetic substrate sheet to obtain a multilayer structure with optical interference effect, thereby exhibiting pearlescent luster. Titanium dioxide (TiO2) pearlescent layers were prepared using a titanium tetrachloride (TiCl4) hydrolysis deposition method. The main reaction process is as follows: TiCl4 + 4H2O → TiCl4 + 4HCl Subsequently, the generated titanium hydroxide (Ti(OH)4) undergoes a bonding reaction with the silicon-oxygen-iron (Si–O–Fe) structure on the surface of the magnetic substrate under controlled pH conditions: Ti(OH)4+Si–O–Fe→Ti(OH)4–Si–O–Fe→Calcined TiO2–Si–O–Fe Through calcination, titanium hydroxide is dehydrated and transformed into a titanium dioxide layer with anatase or rutile structure, ultimately forming a composite magnetic pearlescent pigment with excellent pearlescent effect.

10. A method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The post-treatment steps for the pigments include surface wetting, dispersion treatment, weather resistance enhancement treatment, and brightening treatment.

11. The method for producing a magnetic pearlescent pigment according to claim 1, characterized in that, The brightening post-treatment refers to the use of electrochemical deposition to form a metal coating layer on the surface of the pigment flakes to improve their transparency and gloss. Specifically, a depositable metal ion solution is added to the aqueous system after the pigment preparation is completed. By applying an electric current, the metal ions are reduced to metal atoms on the surface of the pigment flakes and a uniform and dense metal deposition layer is formed, thereby enhancing the optical reflectivity and visual brightness of the pigment.

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