Preparation method of ultra-stable brush-shaped organic silicon microsphere coated modified pigment

Abstract

The invention discloses a preparation method of an ultra-stable brush-shaped organic silicon microsphere coated modified pigment. The method comprises the following steps: weighing raw materials, preparing a pre-emulsified mixed solution, preparing a composite pigment of an organic silicon resin coated pigment, and preparing the brush-shaped organic silicon microsphere coated modified pigment. The preparation method is simple in process and easy to operate, diversified functions such as antibacterial property and specific adsorption resistance can be endowed to the brush-shaped composite pigment particles by selecting or combining the grafting monomers, the stability of the composite pigment particles can be further improved through hydrophilic groups rich in a grafted polymer chain, and the service life of the composite pigment particles is prolonged. The organic silicon resin layer with various excellent performances such as UV radiation resistance and corrosion resistance can also improve the performance of the coated pigment in a specific application system, and the brush-shaped composite pigment particles prepared by the method have a wide application prospect in the field of industrial products such as high-quality functional coatings and the like.

Description

Technical Field

[0001] The invention relates to the technical field of nano composite materials, and in particular to a method for preparing ultra-stable brush-shaped organic silicon microspheres coated with modified pigments. Background Art

[0002] Pigments are often used as colorants and are often added and dispersed in various application systems such as coatings, plastics, and rubber. Compared with dyes, pigments have advantages such as a wide variety, strong tinting power, a wide color spectrum, and non-toxic or low toxicity. However, with the increasing requirements of the consumer market, industry transformation and upgrading, etc., the application performance of pigments in specific systems needs to be optimized and improved. Pigment modification technology can use physical or chemical means to change the particle size and distribution, crystal form or surface polarity of the pigment to achieve the purpose of changing and improving the performance of the pigment. At present, there are two main types of technologies for modifying pigments. One is the pigment coating technology that encapsulates the pigment particles into the microspheres through physical adsorption or chemical bonding, and the other is the surface modification technology that treats the surface of the pigment particles.

[0003] Brush-like microspheres are nano-spherical polymer brushes with a core-shell structure formed by polymer chains connected to the surface of a spherical core with a high grafting density. Silicone has the characteristics of low surface tension, high and low temperature resistance, and corrosion resistance. The use of brush-like silicone microspheres for coating modified pigments has the advantages of high stability and easy functionalization. The grafted polymer chains can prevent the agglomeration and sedimentation of composite pigment particles through steric hindrance and electrostatic interaction, which can further improve the stability of pigment particles. The grafted monomers that form a brush-like structure on the surface of composite pigment particles are abundant in source and can be selected or combined according to needs to give the coated pigments multiple functions such as antibacterial and antifouling.

[0004] In the prior art, the research on the use of silicone to coat modified pigments mainly focuses on the following aspects:

[0005] (1) Using the excellent properties of silicone to improve resins such as polyurethane or acrylic acid to coat pigment particles;

[0006] (2) Using pure silicone resin to coat and modify the pigment;

[0007] (3) The surface of the organosilicon-coated pigment particles is further modified. If the surface has reactive double bonds, graft polymerization modification can be continued, or chemical bonding with other functional materials can be performed after modification with a layer of silane coupling agent;

[0008] However, since silicone materials are low-surface-energy hydrophobic materials, the composite pigment particles after being coated with the pigment are prone to agglomeration and sedimentation, resulting in the composite pigment particles showing the disadvantage of poor stability. In addition, the traditional modified pigment coating process also has the problems of complex process, difficult operation and low universality. The industry is in urgent need of a pigment modification preparation method that can obtain a controllable uniform particle size, strong functionality and good versatility through simple operation. Therefore, the present invention proposes a preparation method for ultra-stable brush-shaped silicone microspheres coated with modified pigments to solve the problems existing in the prior art. Summary of the invention

[0009] In view of the above problems, the purpose of the present invention is to propose a method for preparing ultra-stable brush-shaped silicone microspheres coated modified pigments, so as to solve the problems of poor stability of composite pigment particles, complex process, difficult operation and low universality in the existing silicone coated modified pigment technology.

[0010] In order to achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a method for preparing ultra-stable brush-shaped silicone microspheres coated with modified pigments, comprising the following steps:

[0011] Step 1: First, weigh the pigment, reaction monomer, surfactant, stabilizer, deionized water and hydrolysis-condensation catalyst according to the mass ratio of 1:13:0.5-2.5:0.5:180-250:50 as raw materials for standby use, and then use an ultrasonic cell disruptor to pre-emulsify the raw materials other than the hydrolysis-condensation catalyst;

[0012] Step 2: The pre-emulsified mixed solution is transferred to a three-necked flask and placed in an oil bath for heating. After the temperature is raised to a preset temperature, a hydrolysis-condensation catalyst is uniformly added to the mixed solution, and a composite pigment emulsion coated with silicone on the surface is prepared by a mini-emulsion polymerization method;

[0013] Step 3: Weigh the composite pigment emulsion (calculated based on the solid mass contained in the emulsion) and the initiator in a mass ratio of 40:1 as raw materials for later use, then mix the weighed composite pigment emulsion and initiator and add the grafting monomer, and make a brush-like composite pigment through surface direct initiation grafting polymerization, that is, a brush-like silicone microsphere-coated modified and functionalized pigment.

[0014] A further improvement is that in step one, the pigment is selected from one of phthalocyanine blue, Prussian blue, phthalocyanine green, lead chrome green, iron oxide red or composite titanium red, and the reaction monomer is selected from one or more of methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane or vinyltrimethoxysilane.

[0015] A further improvement is that in the step 1, the surfactant is selected from one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide or alkylphenol polyoxyethylene ether, and the stabilizer is selected from one of n-hexadecane or cyclohexane.

[0016] A further improvement is that in step 1, the hydrolysis-condensation catalyst is selected from one of hydrochloric acid aqueous solution and ammonia water, wherein the concentration of the hydrochloric acid aqueous solution is 1.0wt% and the concentration of the ammonia water is 3.0wt%.

[0017] A further improvement is that in the step 2, the oil bath is heated to 45-70° C. before the hydrolysis-condensation catalyst is added dropwise, and the dropping speed of the hydrolysis-condensation catalyst is 0.3-1.0 mL / min.

[0018] A further improvement is that in the step three, the initiator is a thermal initiator, specifically selected from potassium persulfate or dibenzoyl peroxide, and the specific steps of preparing the brush-shaped composite pigment by the thermal initiator are: first, the weighed composite pigment emulsion and potassium persulfate are poured into a three-necked flask and mixed evenly, then the three-necked flask is placed in an oil bath and heated to 70° C. under nitrogen protection and stabilized for 10 minutes, and then 1.6 g to 3.2 g of the grafted monomer is uniformly added dropwise into the three-necked flask to obtain the brush-shaped composite pigment by surface direct thermal initiation graft polymerization.

[0019] A further improvement is that the grafting monomer is selected from one of acrylic acid monomers or hydroxyethyl acrylamide functional monomers, and the dripping speed of the grafting monomer is 0.3-1.0 mL / min.

[0020] A further improvement is that in the step three, the initiator is a photoinitiator, specifically selected from one of benzophenone or azobisisobutyronitrile, and the specific steps of preparing the brush-shaped composite pigment by the photoinitiator are: first pouring the weighed composite pigment emulsion and benzophenone into a photoreactor, and adding 0.8g to 2.4g of grafting monomer and mixing and stirring, then turning on the ultraviolet radiation lamp under nitrogen protection to irradiate the mixed solution, and obtaining the brush-shaped composite pigment by surface direct photoinitiated graft polymerization.

[0021] The beneficial effects of the present invention are as follows: the present invention prepares a composite pigment of a silicone resin-coated pigment by a mini-emulsion polymerization method, and then initiates the graft polymerization of functional monomers under the initiation of a visible light / thermal initiator to obtain brush-shaped composite pigment particles, and the particle size of the brush-shaped composite pigment particles can be controlled by controlling the amount of functional monomers added. The entire preparation process is simple and easy to operate. By selecting or combining grafted monomers, the brush-shaped composite pigment particles can be given diversified functionality, such as antibacterial properties, resistance to specific adsorption, etc., and the hydrophilic groups rich in the grafted polymer chain can further improve the stability of the composite pigment particles. The silicone resin layer with multiple excellent properties such as resistance to UV radiation and corrosion resistance can also improve the performance of the coated pigment in a specific application system. The brush-shaped composite pigment particles prepared by this method have broad application prospects in the field of high-quality, functional coatings and other industrial products. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic flow chart of a method for preparing a superstable brush-shaped organosilicon microsphere-coated modified pigment of the present invention;

[0023] Figure 2 is a schematic diagram of the strength and fluid dynamics diameter distribution results of the composite pigment particles and brush-shaped composite pigment particles in the embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram comparing the storage stability of the brush-shaped polyhydroxyethyl acrylamide composite pigment particles, the brush-shaped polyacrylic acid composite pigment particles and the composite pigment particles in the embodiments of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the preparation method of a super-stable brush-shaped organic silicon microsphere coated modified pigment of the present invention: the pigment in the raw material is selected from one of phthalocyanine blue, Prussian blue, phthalocyanine green, lead chrome green, iron oxide red or composite titanium red, the following examples use Prussian blue, the reaction monomer is selected from one or more of methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane or vinyltrimethoxysilane, the following examples use a combination of methyltrimethoxysilane, phenyltrimethoxysilane and methylphenyldimethoxysilane, the surfactant is selected from one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide or alkylphenol polyoxyethylene ether, the following examples use sodium dodecyl sulfate, the auxiliary stabilizer is selected from one of n-hexadecane or cyclohexane, the following examples use n-hexadecane, the hydrolysis-condensation catalyst is selected from one of hydrochloric acid aqueous solution or ammonia water, wherein the concentration of the hydrochloric acid aqueous solution is 1.0wt%, the concentration of the ammonia water is 3.0wt%, and the following examples use 1.0wt% hydrochloric acid aqueous solution.

[0027] Embodiment 1

[0028] See also Figure 1 This embodiment provides a method for preparing an ultra-stable brush-shaped organosilicon microsphere-coated modified pigment, comprising the following steps:

[0029] Step 1: Preparation of composite pigments of silicone resin-coated pigments

[0030] 0.2 g of Prussian blue pigment (PB) and 0.05 g of sodium dodecyl sulfate (SDS) were accurately weighed using a precision weighing instrument and transferred to a 50 mL beaker A, and 18.5 g of deionized water was added. Beaker A was then placed in an ice water bath, and an ultrasonic cell disruptor was turned on to ultrasonically disperse the mixed solution in beaker A at a power of 150 W for 2 minutes to obtain a pre-dispersed pigment solution. 0.68 g of methyltrimethoxysilane (MTMS), 0.91 g of phenyltrimethoxysilane (PTMS), 0.99 g of methylphenyldimethoxysilane (MPDMS), 0.1 g of n-hexadecane (HD) and 0.05 g of sodium dodecyl sulfate (SDS) were accurately weighed and transferred to a 50 mL beaker B, and 18.5 g of deionized water was added. 5g deionized water, then beaker B is placed in an ice water bath, and an ultrasonic cell disruptor is turned on to pre-emulsify the mixed solution in beaker B at a power of 150W for 2 minutes to obtain a pre-emulsified monomer solution, and then the pre-dispersed pigment solution and the pre-emulsified monomer solution are mixed and placed in an ice water bath, and an ultrasonic cell disruptor is turned on to pre-emulsify for 2 minutes at a power of 150W. After the pre-emulsification is completed, the mixture is transferred to a 100mL three-necked flask for mechanical stirring, and after the stirring is completed, it is placed in an oil bath and heated to 45-70°C. In this embodiment, after it is heated to 55°C, 10g of a 1.0wt% hydrochloric acid aqueous solution is added dropwise at a dropping speed of 0.5mL / min, and a composite pigment emulsion coated with silicone on the surface is prepared by a mini-emulsion polymerization method;

[0031] The particle size of the prepared composite pigment particles was measured by a laser particle size analyzer, and the results were as follows: when 0.1 g SDS was added (in this embodiment), the particle size of the prepared composite pigment particles was 257 nm, and the particle size distribution was 0.18; when 0.3 g SDS was added, the particle size of the prepared composite pigment particles was 211 nm, and the particle size distribution was 0.10; when 0.5 g SDS was added, the particle size of the prepared composite pigment particles was 198 nm, and the particle size distribution was 0.18;

[0032] Step 2: Preparation of brush-shaped silicone microspheres coated with modified pigments

[0033] 50 g (containing 0.8 g solid mass) of the prepared composite pigment ion emulsion coated with silicone on the surface and 0.02 g potassium persulfate (KPS) were accurately weighed by a precision weighing instrument and transferred to a 100 mL three-necked flask for mechanical stirring. The three-necked flask was then placed in an oil bath and heated to 70° C. under nitrogen protection and stabilized for 10 min. Then, 1.6 g to 3.2 g of acrylic acid (AA) monomer was added dropwise at a rate of 0.3 to 1.0 mL / min with the aid of a 5 mL syringe. The dropping speed in this embodiment was 0.5 mL / min. A brush-like polyacrylic acid composite pigment was obtained by surface direct thermally initiated graft polymerization.

[0034] The particle size of brush-like composite pigment particles rich in surface carboxylic acid groups prepared by direct thermal initiation method at different amounts of acrylic acid monomer added was determined by a laser particle size analyzer. The results are as follows: the particle size of the brush-like composite pigment particles prepared when 1.6g of acrylic acid was added was 252nm; the particle size of the brush-like composite pigment particles prepared when 2.4g of acrylic acid was added was 485nm; the particle size of the brush-like composite pigment particles prepared when 3.2g of acrylic acid was added was 686nm.

[0035] Embodiment 2

[0036] See also Figure 1 This embodiment provides a method for preparing an ultra-stable brush-shaped organosilicon microsphere-coated modified pigment, comprising the following steps:

[0037] Step 1: Preparation of composite pigments of silicone resin-coated pigments

[0038] 0.2 g of Prussian blue pigment (PB) and 0.15 g of sodium dodecyl sulfate (SDS) were accurately weighed using a precision weighing instrument and transferred to a 50 mL beaker A, and 18.4 g of deionized water was added. Then, beaker A was placed in an ice water bath, and an ultrasonic cell disruptor was turned on to ultrasonically disperse the mixed solution in beaker A at a power of 150 W for 2 minutes to obtain a pre-dispersed pigment solution. Then, 0.68 g of methyltrimethoxysilane (MTMS), 0.91 g of phenyltrimethoxysilane (PTMS), 0.99 g of methylphenyldimethoxysilane (MPDMS), 0.1 g of n-hexadecane (HD) and 0.15 g of sodium dodecyl sulfate (SDS) were accurately weighed and transferred to a 50 mL beaker B, and 18.4 g of deionized water was added. 4g deionized water, then beaker B is placed in an ice water bath, and an ultrasonic cell disruptor is turned on to pre-emulsify the mixed solution in beaker B at a power of 150W for 2 minutes to obtain a pre-emulsified monomer solution, and then the pre-dispersed pigment solution and the pre-emulsified monomer solution are mixed and placed in an ice water bath, and an ultrasonic cell disruptor is turned on to pre-emulsify for 2 minutes at a power of 150W, after the pre-emulsification is completed, the mixture is transferred to a 100mL three-necked flask for mechanical stirring, and after the stirring is completed, it is placed in an oil bath and heated to 45-70°C. In this embodiment, after it is heated to 55°C, 10g of a 1.0wt% hydrochloric acid aqueous solution is added dropwise at a dropping speed of 0.5mL / min, and a composite pigment emulsion coated with silicone on the surface is prepared by a mini-emulsion polymerization method;

[0039] The particle size of the prepared composite pigment particles was measured by a laser particle size analyzer, and the results were as follows: when 0.1 g SDS was added, the particle size of the prepared composite pigment particles was 257 nm, and the particle size distribution was 0.18; when 0.3 g SDS was added (this embodiment), the particle size of the prepared composite pigment particles was 211 nm, and the particle size distribution was 0.10; when 0.5 g SDS was added, the particle size of the prepared composite pigment particles was 198 nm, and the particle size distribution was 0.18;

[0040] Step 2: Preparation of brush-shaped silicone microspheres coated with modified pigments

[0041] Using a precision weighing instrument, 50 g (containing 0.8 g solid mass) of the pigment emulsion coated with silicone prepared in step 1 and 0.02 g of benzophenone are accurately weighed and transferred to a photoreactor, and 0.8 g to 2.4 g of hydroxyethyl acrylamide (HEAA) functional monomer is added into the photoreactor and mixed and stirred, and then a 175 W ultraviolet radiation lamp is turned on under nitrogen protection to irradiate the mixed solution, and a brush-like polyhydroxyethyl acrylamide composite pigment is obtained by surface direct photoinitiated graft polymerization;

[0042] The particle size of the brush-like composite pigment particles prepared by the direct photoinitiation method at different addition amounts of hydroxyethyl acrylamide monomer was measured by a laser particle size analyzer, and the results were as follows: the particle size of the brush-like composite pigment particles prepared when 0.8 g of hydroxyethyl acrylamide was added was 213 nm; the particle size of the brush-like composite pigment particles prepared when 1.6 g of hydroxyethyl acrylamide was added was 325 nm; the particle size of the brush-like composite pigment particles prepared when 2.4 g of hydroxyethyl acrylamide was added was 390 nm.

[0043] like Figure 2 The intensity and hydrodynamic diameter distribution results of the composite pigment particles and brush-shaped composite pigment particles are shown. Figure 2 (a) represents composite pigment particles. Figure 2 (b) represents brush-like polyacrylic acid composite pigment particles. Figure 2 (c) represents brush-like poly(hydroxyethyl)acrylamide composite pigment particles.

[0044] like Figure 3 The storage stability comparison of the brush-like polyhydroxyethyl acrylamide composite pigment particles, the brush-like polyacrylic acid composite pigment particles and the composite pigment particles is shown. Figure 3 (a) represents composite pigment particles. Figure 3 (b) represents brush-like polyacrylic acid composite pigment particles. Figure 3 (c) represents brush-like poly(hydroxyethyl)acrylamide composite pigment particles.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing ultra-stable brush-shaped silicone microspheres coated with modified pigments, characterized in that: The following steps are involved: Step 1: First, weigh the pigment, reaction monomer, surfactant, stabilizer, deionized water and hydrolysis-condensation catalyst according to the mass ratio of 1:13:0.5-2.5:0.5:180-250:50 as raw materials for standby use, and then use an ultrasonic cell disruptor to pre-emulsify the raw materials other than the hydrolysis-condensation catalyst; Step 2: The pre-emulsified mixed solution is transferred to a three-necked flask and placed in an oil bath for heating. After the temperature is raised to a preset temperature, a hydrolysis-condensation catalyst is uniformly added to the mixed solution, and a composite pigment emulsion coated with silicone on the surface is prepared by a mini-emulsion polymerization method; Step 3: Weigh the composite pigment emulsion and initiator in a mass ratio of 40:1 as raw materials for use, where the mass ratio is the ratio of the solid mass in the composite pigment emulsion to the mass of the initiator. Mix the weighed composite pigment emulsion and initiator and add grafting monomers to prepare brush-like composite pigments through surface direct grafting polymerization, which are brush-like silicone microsphere-coated modified and functionalized pigments.

2. The method for preparing a superstable brush-shaped silicone microsphere coated modified pigment according to claim 1, characterized in that: In the step 1, the pigment is selected from one of phthalocyanine blue, Prussian blue, phthalocyanine green, lead chrome green, iron oxide red or composite titanium red, and the reactive monomer is selected from one or more of methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane or vinyltrimethoxysilane.

3. The method for preparing a superstable brush-shaped silicone microsphere coated modified pigment according to claim 1, characterized in that: In the step 1, the surfactant is selected from one of sodium dodecyl sulfate, hexadecyl trimethyl ammonium bromide or alkylphenol polyoxyethylene ether, and the stabilizer is selected from one of n-hexadecane or cyclohexane.

4. The method for preparing a superstable brush-shaped silicone microsphere coated modified pigment according to claim 1, characterized in that: In the step 1, the hydrolysis-condensation catalyst is selected from one of a hydrochloric acid aqueous solution and an ammonia aqueous solution, wherein the concentration of the hydrochloric acid aqueous solution is 1.0 wt % and the concentration of the ammonia aqueous solution is 3.0 wt %.

5. The method for preparing a superstable brush-shaped silicone microsphere coated modified pigment according to claim 1, characterized in that: In the step 2, the oil bath is heated to 45-70° C. and then a hydrolysis-condensation catalyst is added dropwise, and the dropping speed of the hydrolysis-condensation catalyst is 0.3-1.0 mL / min.

6. The method for preparing a superstable brush-shaped organosilicon microsphere coated modified pigment according to claim 1, characterized in that: In the step three, the initiator is a thermal initiator, specifically selected from potassium persulfate or dibenzoyl peroxide. The specific steps of preparing the brush-shaped composite pigment by the thermal initiator are: first pouring the weighed composite pigment emulsion and potassium persulfate into a three-necked flask and mixing them evenly, then placing the three-necked flask in an oil bath and heating to 70° C. under nitrogen protection and stabilizing for 10 minutes, then uniformly adding 1.6 g to 3.2 g of grafting monomer into the three-necked flask, and obtaining the brush-shaped composite pigment by surface direct thermal initiation graft polymerization.

7. The method for preparing a superstable brush-shaped silicone microsphere coated modified pigment according to claim 6, characterized in that: The grafting monomer is selected from one of acrylic acid monomers or hydroxyethyl acrylamide functional monomers, and the dripping speed of the grafting monomer is 0.3-1.0 mL / min.

8. The method for preparing a superstable brush-shaped organosilicon microsphere coated modified pigment according to claim 1, characterized in that: In the step three, the initiator is a photoinitiator, specifically selected from one of benzophenone or azobisisobutyronitrile. The specific steps of preparing the brush-shaped composite pigment by the photoinitiator are: first pouring the weighed composite pigment emulsion and benzophenone into a photoreactor, adding 0.8g to 2.4g of grafting monomer at the same time and mixing and stirring, then turning on the ultraviolet radiation lamp under nitrogen protection to irradiate the mixed solution, and obtaining the brush-shaped composite pigment by surface direct photoinitiated graft polymerization.

Images