Inorganic pigment dispersant, inorganic pigment paste and preparation method thereof

Abstract

The present invention provides an inorganic pigment dispersant having a block structure. The long-chain hydrophilic chain segments are dissolved in water after being neutralized and ionized by alkali solution, which can significantly increase the double layer thickness of the pigment particles, thereby being more conducive to ensuring the dispersion stability of the pigment particles. The present invention also provides an inorganic pigment paste with a high inorganic pigment content. The aforementioned dispersant with a block structure increases the double layer thickness of the pigment particles, ensures the dispersion stability of the pigment particles, and solves the problem that existing inorganic pigments are difficult to disperse and refine, and have poor storage stability, thereby affecting the printing effect. Through the special dispersant, resin and formula design of the present invention, the inorganic ink prepared has a fine particle size, low viscosity, good storage stability, and excellent shear resistance. It is expected to be used as an intermediate for preparing highly weather-resistant gravure printing inorganic ink and be applied in the field of automotive interior decorative films.

Description

Technical Field

[0001] The invention relates to a water-based ink paste for gravure printing and a preparation method thereof, in particular to an inorganic pigment dispersant and an inorganic pigment paste with a high inorganic pigment content. Background Art

[0002] Gravure inks have evolved from benzene-based inks to solvent-based inks and then to alcohol-soluble inks. Although alcohol-soluble inks produce excellent printing results in gravure printing of cigarette packages, they require the addition of large amounts of solvents during use, polluting the environment and harming the printers. Currently, the gravure printing process is undergoing a transformation, with a preferred approach being to adapt existing gravure machines to environmentally friendly, low-cost water-based gravure inks (abbreviated as water-based inks) by modifying them, increasing the size and length of drying equipment, and lightening the printing plates. The inorganic pigments in water-based inks are superior to organic pigments in terms of weather resistance, heat resistance, and solvent resistance, and are expected to be widely used.

[0003] However, due to the high proportion of inorganic pigments in water-based gravure inks, the dispersion stability of inorganic pigments, especially the stability of dispersions with high inorganic pigment content, has always been a challenge in the industry. This results in low tinting strength and poor color vividness. If the dispersion stability of high inorganic pigment content dispersions (inorganic pigment pastes with high inorganic pigment content) can be improved, it is expected that inorganic water-based inks with high tinting strength and vividness can be formulated. Summary of the Invention

[0004] The present invention aims to address the deficiencies of the prior art by providing a specially designed dispersant having amphiphilic hydrophilic and lipophilic segments, which can be used as a dispersant for dispersing and stabilizing inorganic pigments, thereby improving the tinting strength and color vividness of the inorganic pigments. Specifically, the chemical structural formula of the dispersant of the present invention is:

[0005]

[0006] Wherein, n1 is the degree of polymerization of the methyl methacrylate monomer unit, n1=3 to 5; n2 is the degree of polymerization of the methacrylic acid monomer unit, n2=22 to 30. In some preferred embodiments of the present invention, n1=4, n2=24.

[0007] The above-mentioned dispersant is an amphiphilic macromolecular dispersant with a long hydrophilic chain segment (polymethacrylic acid chain segment) and a short lipophilic chain segment (polymethyl methacrylate). Compared with traditional small molecule dispersants, during the dispersion and stabilization process of the pigment, the lipophilic chain segment of the dispersant can form a multi-point riveted adsorption mechanism with the pigment surface, and the long hydrophilic chain segment can be fully dissolved in the aqueous phase to form a polymer protective layer, which greatly increases the double layer thickness of the pigment particles, thereby ensuring the dispersion stability of the pigment particles.

[0008] The aforementioned dispersants utilize polymethacrylic acid segments as hydrophilic segments, which offer significant advantages over polyacrylic acid or polyitaconic acid segments. While these segments are also hydrophilic, their lengths are uncontrollable, making them incapable of functioning as amphiphilic dispersants. If the degrees of polymerization (n1 and n2) are uncontrollable, an amphiphilic product cannot be obtained.

[0009] The present invention also provides a method for preparing the above-mentioned dispersant, which at least comprises:

[0010] (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 37.84-51.6 g of MAA, and 106 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80°C for 2 hours;

[0011] The structural formula of the precursor is:

[0012] Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0013] The preparation of the precursor is based on existing techniques, including but not limited to references such as Ferguson CJ, Hughes RJ, Nguyen D, Pham BTT, Gilbert G, Serelis AK, Such CH, and Hawkett B S. Ab initioemulsion polymerization by RAFT-controlled self-assembly [J]. Macromolecules, 2005, 38(6): 2191-2204.

[0014] (2) Add 6-10 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, remove oxygen through nitrogen flow, and react at 80 ° C for 12 hours;

[0015] (3) Cooling to room temperature, using cyclohexane as a precipitant to precipitate the dispersant, and vacuum drying to obtain the dispersant having a block structure.

[0016] In the present invention, the synthesis of dispersant adopts mature RAFT technology, and its product structure can be determined without doubt. RAFT technology can very effectively control the polymerization of monomers by the reversible degeneration transfer of growing free radicals, and realizes the controllable regulation of polymer microstructure (such as synthetic block copolymers, etc.) and polymerization degree. It can be applied to the homopolymerization and copolymerization system of various monomers, and is applicable to almost all vinyl monomers, and the reaction conditions are no different from traditional free radical polymerization, and are applicable to the various reaction systems such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization. The present invention adopts the mode of RAFT solution polymerization, and the ratio control of each component in the monomer addition order and synthesis formula is obtained to obtain dispersant with different polymerization degree and polymeric structure. Specifically, block copolymer can be regulated by monomer segmented feeding, and random copolymer can be regulated by mixed monomer single feeding.

[0017] Compared with the “single-point adsorption” of traditional conventional small molecule dispersants, the present invention adopts a block structure dispersant with long-chain hydrophilic segments that are dissolved in water after neutralization and ionization with alkali solution (this type of dispersant with an amphiphilic block structure forms a “comb” structure in the water dispersion system, and the hydrophilic segments stretch toward the water phase and dissolve in water), which can greatly increase the thickness of the double electric layer of the pigment particles, thereby being more conducive to ensuring the dispersion stability of the pigment particles. The dispersant with a random copolymer structure only adopts a random copolymerization method, and performs alkali solution neutralization and ionization to ionize the carboxylic acid groups on the MAA. The dispersant is adsorbed and “collapsed” on the surface of the inorganic pigment in the form of a “linear” polymer, realizing a “multi-point adsorption” stabilization mechanism. Compared with dispersants with random copolymer structures, dispersants with block structures can greatly increase the thickness of the double electric layer of pigment particles, thereby being more conducive to ensuring the dispersion stability of pigment particles. The principle diagram is shown in the attached manual. Figure 1 Therefore, the present invention creatively uses a macromolecular dispersant whose main component is a block copolymer of MMA and MAA to disperse inorganic pigments, which is essentially different from a macromolecular dispersant of a random copolymer.

[0018] The above-mentioned random copolymer dispersant also uses MMA and MAA, and its general structure is as follows:

[0019]

[0020] Wherein, n1 is the degree of polymerization of the methyl methacrylate monomer unit, n1=3-5; n2 is the degree of polymerization of the methacrylic acid monomer unit, n2=22-30. The preparation process is as follows:

[0021] (1) 3 g of the precursor, 0.4 g of azobisisocyanovaleric acid initiator, 37.84-51.6 g of MAA, 6-10 g of MMA, and 138 g of dioxane were mixed, and the mixture was reacted at 80° C. for 12 hours after nitrogen was passed through the mixture to remove oxygen.

[0022] The structural formula of the precursor is:

[0023] Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0024] (2) Cooling to room temperature, using cyclohexane as a precipitant to precipitate the dispersant, and vacuum drying to obtain the dispersant having a random copolymer structure.

[0025] The present invention also provides an inorganic pigment paste with a high inorganic pigment content. This paste utilizes the aforementioned block-structured dispersant to increase the thickness of the pigment particles' electrical double layer, ensuring dispersion stability. This addresses the issues with existing inorganic pigments, such as difficulty dispersing and refining, and poor storage stability, which can affect printing quality. Specifically, the inorganic pigment paste comprises an inorganic pigment and the aforementioned block-structured dispersant; the mass ratio of the inorganic pigment to the dispersant is 10:2-3.

[0026] In some preferred embodiments of the present invention, the inorganic pigment paste is composed of the following raw materials in the following weight ratio: 10 parts of pigment, 22-28 parts of dispersing resin, 2-3 parts of dispersant, 0.01-0.03 parts of alkaline neutralizer, 0.04-0.06 parts of defoaming agent, and 10-14 parts of purified water.

[0027] The present invention also designs and synthesizes a dispersing resin, which can be used for the aforementioned inorganic pigment paste. The dispersing resin is prepared by the following method:

[0028] (1) Add 4g Emulsogen APS 100, 1.1g NE-10 and 3g n-butyl acrylate monomer to 90g pure water, stir at 800rpm and heat to 90℃, reduce the stirring speed to 300rpm, add 4g potassium persulfate aqueous solution (0.3g potassium persulfate dissolved in 4g pure water), after the reaction system appears blue light, add 62g n-butyl acrylate monomer and 12g potassium persulfate aqueous solution (2g potassium persulfate dissolved in 10g pure water), both of which are added at the same time, and the addition time is 7h; then reduce the temperature of the reaction system to 63℃, add 1.5g isopropyl alcohol, and then add 6g n-butyl acrylate monomer, 18g AC-76, 10g methyl methacrylate monomer, 0.8g isopropylbenzene hydroperoxide and 0.6g The monomer addition phase was stirred at 250 rpm with 2 g of NE-10 stirred for 2 hours. 6.4 g of sodium bicarbonate aqueous solution (0.4 g of sodium bicarbonate dissolved in 6 g of pure water) was added. The rate of addition of the sodium bicarbonate aqueous solution was adjusted to maintain the pH of the reaction system between 5.5 and 7.5. After the monomer addition phase and the sodium bicarbonate aqueous solution were added, the mixture was stirred at room temperature for 1.5 hours. 2.08 g of tert-butyl hydroperoxide aqueous solution (0.08 g of tert-butyl hydroperoxide dissolved in 2 g of pure water) was added. The mixture was stirred at this temperature for 10 minutes. 2.08 g of Rongalite aqueous solution (0.08 g of Rongalite dissolved in 2 g of pure water) was added. The mixture was stirred at this temperature for 10 minutes. The mixture was cooled to room temperature and discharged to obtain a silicone acrylic emulsion with a silicone monomer content of approximately 23%.

[0029] (2) Take 50g of the above-mentioned silicone acrylic emulsion and add it into a dispersion kettle. Start stirring. At a stirring speed of 200-300rpm, add 30g of sodium silicate and 50 parts of silicon dioxide dispersion (silicon dioxide dispersion with a solid content of 30%-50% and a particle size of ≤100nm). Keep stirring for 0.5-1h and then filter the material to obtain the dispersed resin.

[0030] Dispersing resin participates in the grinding of inorganic pigment paste, plays an auxiliary role in dispersing and stabilizing the inorganic pigment, and forms a synergistic effect with the dispersant; and it can greatly improve the rigidity and weather resistance of the coating, which is beneficial to improving the resistance of the ink layer in subsequent ink mixing.

[0031] In the present invention, the inorganic pigments include but are not limited to: inorganic iron red pigment, iron oxide yellow, iron oxide blue, and inorganic carbon black.

[0032] The present invention also provides a method for preparing the aforementioned inorganic pigment paste, comprising: adding 22-28 parts of a dispersing resin into a dispersion kettle, starting stirring, maintaining the rotation speed at 100-200 rpm, then sequentially adding 10-14 parts of purified water, 0.01-0.03 parts of an alkaline neutralizer, 2-3 parts of a dispersant, 0.04-0.06 parts of a defoaming agent and 10 parts of a pigment, stirring and mixing at a rate of 200-500 rpm, and then transferring the mixture to a horizontal sand mill, grinding until the paste particle size reaches less than 300 nm, and then filtering the material to obtain the inorganic pigment paste.

[0033] Compared with the prior art, the beneficial effects of the present invention are: through the dispersant designed by the present invention, the inorganic pigment paste prepared by the present invention has fine particle size, low viscosity, high inorganic pigment content, good storage stability, and strong shear stability. It is expected to be used as an intermediate product for the preparation of high-weather-resistant gravure printing inorganic ink and be applied to the field of automotive interior decorative films. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 (a) is a schematic diagram of the “multi-point adsorption” stabilization mechanism, and (b) is a schematic diagram of the block “comb” type stabilization mechanism. DETAILED DESCRIPTION

[0035] In the present invention, the silicon dioxide dispersion, alkaline neutralizer, defoamer and purified water are all commercially available products.

[0036] The silica dispersion has a solid content of 30%-50% and a particle size of ≤100 nm (such as R301, AkzoNoble; R302, AkzoNoble; R303, AkzoNoble; R402, AkzoNoble; R1050, AkzoNoble; R1020, AkzoNoble; R1010, AkzoNoble; R900, AkzoNoble; WV33, AkzoNoble; XP4080, AkzoNoble), with R1020 (AkzoNoble) being particularly preferred.

[0037] The alkaline neutralizing agent can be any one of sodium hydroxide, potassium hydroxide, monoethanolamine, diethanolamine, and triethanolamine, with monoethanolamine being particularly preferred.

[0038] The defoamer of the present invention is a lower alcohol defoamer (such as DF 3163, Deqian Company), mineral oil defoamers (such as W-074, Deqian Company; W-082, Deqian Company; W-098, Deqian Company; ADVANTAGEAM-1512, ASHLAND-AQUALON Company), silicone defoamers (such as G308, Milliken Chemical Group Co., Ltd., USA) or a mixture of two or more in any proportion, preferably lower alcohol defoamers, especially preferably DF 3163 (Deqian Company).

[0039] The purified water refers to tap water purified by an LRO PVC primary reverse osmosis pure water device (Shanghai Sina Light Industry Machinery Equipment Co., Ltd.) to a conductivity of no more than 50 μS / cm (25° C.).

[0040] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0041] In the following examples, the precursors were prepared by the method described in the literature Ferguson CJ, Hughes RJ, Nguyen D, Pham B TT, Gilbert RG, Serelis AK, Such CH, Hawkett B S. Ab initio emulsion polymerization by RAFT-controlled self-assembly [J]. Macromolecules, 2005, 38(6): 2191-2204. The product was tested by the test method described in the literature to obtain the structural formula: Here, Z is an alkylthio group having four carbon atoms, and X is an isopropyl group.

[0042] In the following examples, the preparation method of the dispersion resin is as follows:

[0043] (1) Add 4 g of Emulsogen APS 100 (Kline), 1.1 g (1.5 parts by weight) of NE-10 (ADEKA), and 3 g of n-butyl acrylate (Shanghai Hechuang Chemical Technology Co., Ltd.) monomer to 90 g of pure water, stir at a stirring speed of 800 rpm and heat to 90°C, reduce the stirring speed to 300 rpm, add 4 g of potassium persulfate (Suzhou Huahang Chemical Technology Co., Ltd.) aqueous solution (0.3 g of potassium persulfate dissolved in 4 g of pure water), and after the reaction system shows obvious blue light, add 62 g of n-butyl acrylate monomer (Shanghai Hechuang Chemical Technology Co., Ltd.) and 12 g of potassium persulfate aqueous solution (Suzhou Huahang Chemical Technology Co., Ltd.) dropwise at the same time. (2g potassium persulfate was dissolved in 10g pure water), the two were added at the same time, the addition time was 7h, and then the temperature of the reaction system was reduced to 63 ° C, 1.5g isopropyl alcohol (Yonghua Chemical Technology (Jiangsu) Co., Ltd.) was added, and then 6g n-butyl acrylate monomer (Shanghai Hechuang Chemical Technology Co., Ltd.), 18g AC-76 (Ark (Fogang) Chemical Materials Co., Ltd.), 10g methyl methacrylate monomer (Shanghai Hechuang Chemical Technology Co., Ltd.), 0.8g isopropylbenzene hydroperoxide (SIGMA-ALDRICH), 0.6g N,N-dimethyltoluidine (Tianjin CITIC Kaitai Chemical Co., Ltd.), 2g The monomer addition phase was stirred with NE-10 (ADEKA) at a stirring speed of 250 rpm for 2 hours, and 6.4 g of sodium bicarbonate aqueous solution (0.4 g of sodium bicarbonate dissolved in 6 g of pure water) was added. The addition rate of the sodium bicarbonate aqueous solution was adjusted to maintain the pH value of the reaction system between 5.5 and 7.5. The pH value of the reaction system was measured every 20 minutes. After the monomer addition phase and the sodium bicarbonate aqueous solution were added, the mixture was stirred at room temperature for 1.5 hours. 2.08 g of tert-butyl hydroperoxide aqueous solution (0.08 g of tert-butyl hydroperoxide dissolved in 2 g of pure water) was added and stirred at temperature for 10 minutes. 2.08 g of Rongalite (Shanghai Fengrui Chemical Co., Ltd.) aqueous solution (0.08 g of Rongalite dissolved in 2 g of pure water) was added and stirred at temperature for 10 minutes. Finally, the mixture was cooled to room temperature and discharged to obtain a silicone acrylic emulsion with a silicone monomer content of nearly 23%.

[0044] (2) Take 50g of the above-mentioned silicone acrylic emulsion and add it into a dispersion kettle, start stirring, add 30g of sodium silicate (Jiangxi Yigao Chemical Industry Development Co., Ltd.) and 50 parts of silicon dioxide dispersion at a stirring speed of 200-300rpm, keep stirring for 0.5-1h, and then filter and discharge the material to obtain the dispersed resin.

[0045] The particle size test of the dispersed resin and inorganic pigment paste was carried out on a Malvern ZETASIZER 3000HAS particle size analyzer at a test temperature of 25°C.

[0046] The viscosity of the inorganic pigment paste was measured on a BGD 152S smart touch viscometer.

[0047] The storage stability of inorganic pigment paste means that the inorganic pigment paste is left to stand at 60°C for 9 days without precipitation or stratification, and the viscosity change before and after hot storage does not exceed 30%, which means that the storage stability of the inorganic pigment paste is greater than 6 months.

[0048] The shear stability of inorganic pigment paste refers to the process of dispersing the inorganic pigment paste at a high speed of 3000 rpm on an intelligent dispersing sand mill (Hangzhou Qiwei Instrument Co., Ltd.) for 30 minutes, and then filtering the inorganic pigment paste through a 200-mesh stainless steel filter. The absence of filter residue on the filter indicates that the inorganic pigment paste has good shear stability.

[0049] The particle size and particle size distribution of the dispersed resin prepared by the present invention are 89.63 nm and 0.234 respectively. The fine particle size of the resin is beneficial for acting as a synergistic dispersion stabilizer on the surface of the inorganic pigment particles.

[0050] In the following examples, the molecular weight of the dispersant was characterized on a gel permeation chromatograph (GPC) using a Waters 1525-2414-717 GPC instrument, with tetrahydrofuran as the eluent and narrow-distribution polystyrene standards for calibration.

[0051] Example 1 (preparing inorganic pigment paste with conventional small molecule dispersant):

[0052] 32 parts of purified water, 2 parts of dispersant TEGO Dispers 740W (TEGO company), 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess) was added into the dispersion kettle, stirred at 200 rpm until uniformly mixed, and then transferred to a horizontal sand mill. After grinding for 6 times, the material was filtered to obtain a water-based inorganic red slurry.

[0053] Example 2 (conventional small molecule dispersant + dispersing resin to prepare inorganic pigment paste):

[0054] Add 22 parts of dispersion resin into the dispersion kettle, start stirring, keep the speed at 100 rpm, then add 10 parts of purified water, 2 parts of dispersant TEGO Dispers 740W (TEGO company), 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess), and stirred and mixed at a rate of 200 rpm, and then transferred to a horizontal sand mill, ground for 6 times, and then filtered to obtain a water-based inorganic red slurry.

[0055] Example 3 (preparing inorganic pigment paste with a dispersant having a block copolymer structure):

[0056] Step 1: Preparation of dispersant:

[0057] (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 41.28 g of MAA, and 106 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 2 hours. The structural formula of the precursor is: Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0058] (2) Add 8 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, remove oxygen through nitrogen flow, and react at 80 ° C for 12 hours;

[0059] (3) After cooling to room temperature, the dispersant was precipitated with cyclohexane as a precipitant, and the product was dried in vacuo. The molecular weight of the product was gradually increased with the addition of MAA and MMA monomers by GPC (gel permeation chromatography). The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The structural formula was measured to be:

[0060]

[0061] Among them, n1=4, n2=24.

[0062] Step 2: Preparation of inorganic pigment paste:

[0063] 32 parts of purified water, 0.01 parts of monoethanolamine (BASF), 2 parts of the aforementioned dispersant with a block copolymer structure of n1=4, n2=24, 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess) was added into the dispersion kettle, stirred at 200 rpm until uniformly mixed, and then transferred to a horizontal sand mill. After grinding for 4 times, the material was filtered to obtain a water-based inorganic red slurry.

[0064] Example 4 (preparation of inorganic pigment paste using a dispersant and a dispersing resin having a block copolymer structure):

[0065] Step 1: Preparation of dispersant:

[0066] (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 41.28 g of MAA, and 106 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 2 hours. The structural formula of the precursor is: Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0067] (2) Add 8 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, remove oxygen through nitrogen flow, and react at 80 ° C for 12 hours;

[0068] (3) After cooling to room temperature, the dispersant was precipitated with cyclohexane as a precipitant, and the product was dried under vacuum. The molecular weight characterization results were as follows:

[0069] Table 1. Molecular weight characterization results of block copolymer dispersants

[0070]

[0071] GPC (gel permeation chromatography) testing shows that the molecular weight increases gradually with the addition of MAA and MMA monomers. The measured molecular weight is basically consistent with the designed molecular weight, and the controllability is good. Its structural formula is:

[0072]

[0073] Among them, n1=4, n2=24.

[0074] Step 2: Preparation of inorganic pigment paste:

[0075] 22 parts of dispersing resin were added to the dispersing kettle, stirring was started, and the speed was maintained at 100 rpm. Then 10 parts of purified water, 0.01 parts of monoethanolamine (BASF), 2 parts of the above-mentioned dispersant with block copolymer structure of n1=4, n2=24, 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess), and stirred and mixed at a rate of 200 rpm, and then transferred to a horizontal sand mill, and ground until the color paste particle size reached less than 300 nm (3 passes), and then filtered to obtain a water-based inorganic red paste.

[0076] Example 5 (preparing an inorganic pigment paste with a dispersant having a random copolymer structure):

[0077] Step 1: Preparation of dispersant:

[0078] (1) 3 g of the precursor, 0.4 g of azobisisocyanovaleric acid initiator, 41.28 g of MAA, 8 g of MMA, and 138 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 12 hours. The structural formula of the precursor is: Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0079] (2) After cooling to room temperature, the dispersant was precipitated using cyclohexane as a precipitant, and vacuum dried to obtain a dispersant with a random copolymer structure. The molecular weight characterization results are as follows:

[0080] Table 2. Molecular weight characterization results of random copolymer dispersants

[0081] dispersants <![CDATA[Designed molecular weight / (g·mol -1 )]]> <![CDATA[Measured molecular weight / (g·mol -1 )]]> Molecular weight distribution Random copolymer dispersant (n1=4, n2=24) 2693 2720 1.39

[0082] GPC (gel permeation chromatography) testing shows that the molecular weight increases once the mixed monomers of MAA and MMA are added. The measured molecular weight is basically consistent with the designed molecular weight, and the controllability is good. The structural formula is as follows:

[0083]

[0084] Among them, n1=4, n2=24.

[0085] Step 2: Preparation of inorganic pigment paste:

[0086] 32 parts of purified water, 0.01 parts of monoethanolamine (BASF), 2 parts of the aforementioned dispersant with a random copolymer structure of n1=4, n2=24, 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess) was added into the dispersion kettle, stirred at 200 rpm until uniformly mixed, and then transferred to a horizontal sand mill. After grinding for 5 times, the material was filtered to obtain a water-based inorganic red slurry.

[0087] Example 6 (preparation of inorganic pigment paste using a dispersant and a dispersing resin having a random copolymer structure):

[0088] Step 1: Preparation of dispersant:

[0089] (1) 3 g of the precursor, 0.4 g of azobisisocyanovaleric acid initiator, 41.28 g of MAA, 8 g of MMA, and 138 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 12 hours. The structural formula of the precursor is:

[0090] Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0091] (2) After cooling to room temperature, the dispersant was precipitated using cyclohexane as a precipitant, and vacuum dried to obtain a random copolymer dispersant. The molecular weight of the dispersant increased with the addition of MAA and MMA mixed monomers. The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The measured structural formula was as follows:

[0092]

[0093] Among them, n1=4, n2=24.

[0094] Step 2: Preparation of inorganic pigment paste:

[0095] 22 parts of dispersion resin were added to the dispersion kettle, stirring was started, and the speed was maintained at 100 rpm. Then 10 parts of purified water, 0.01 parts of monoethanolamine (BASF), 2 parts of the above-mentioned dispersant with random copolymer structure of n1=4, n2=24, 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess), and stirred and mixed at a rate of 200 rpm, and then transferred to a horizontal sand mill, and ground until the color paste particle size reached 4, and then filtered to obtain a water-based inorganic red paste.

[0096] Example 7 (dispersed resin configured with inorganic pigment paste):

[0097] Add 24 parts of dispersion resin into the dispersion kettle, start stirring, keep the speed at 100 rpm, then add 10 parts of purified water, 0.04 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess), and stirred and mixed at a rate of 200 rpm, and then transferred to a horizontal sand mill, and ground until the color paste particle size reached 7, and then filtered to obtain a water-based inorganic red paste.

[0098] Example 8 (preparation of inorganic pigment paste using a dispersant and a dispersing resin having a block copolymer structure):

[0099] Step 1: Preparation of dispersant:

[0100] (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 37.84 g of MAA, and 106 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 2 hours. The structural formula of the precursor is: Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0101] (2) Add 6 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, remove oxygen through nitrogen flow, and react at 80 ° C for 12 hours;

[0102] (3) After cooling to room temperature, the dispersant was precipitated with cyclohexane as a precipitant, and the product was dried in vacuo. The molecular weight of the product was gradually increased with the addition of MAA and MMA monomers by GPC (gel permeation chromatography). The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The structural formula was measured to be:

[0103]

[0104] Among them, n1=3, n2=22.

[0105] Step 2: Preparation of inorganic pigment paste:

[0106] 24 parts of the dispersion resin were added to the dispersion kettle, stirring was started, and the speed was maintained at 100 rpm. Then 12 parts of purified water, 0.03 parts of monoethanolamine (BASF), 3 parts of the above-mentioned dispersant with a block copolymer structure of n1=3, n2=22, 0.05 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess), and stirred and mixed at a speed of 200 rpm, and then transferred to a horizontal sand mill, and ground until the color paste particle size reached less than 300 nm (3 passes), and then filtered to obtain a water-based inorganic yellow paste.

[0107] Example 9 (preparation of inorganic pigment paste using a dispersant and a dispersing resin having a random copolymer structure):

[0108] Step 1: Preparation of dispersant:

[0109] (1) 3 g of the precursor, 0.4 g of azobisisocyanovaleric acid initiator, 37.84 g of MAA, 6 g of MMA, and 138 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 12 hours. The structural formula of the precursor is:

[0110] Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0111] (2) After cooling to room temperature, the dispersant was precipitated using cyclohexane as a precipitant, and vacuum dried to obtain a random copolymer dispersant. The molecular weight of the dispersant increased with the addition of MAA and MMA mixed monomers, and the measured molecular weight was basically consistent with the designed molecular weight, with good controllability. The measured structural formula is as follows:

[0112]

[0113] Among them, n1=3, n2=22.

[0114] Step 2: Preparation of inorganic pigment paste:

[0115] 24 parts of dispersion resin were added to the dispersion kettle, stirring was started, and the speed was maintained at 100 rpm. Then 12 parts of purified water, 0.03 parts of monoethanolamine (BASF), 3 parts of the above-mentioned dispersant with random copolymer structure of n1=3, n2=22, 0.05 parts of DF 3163 (Deqian Company) and 10 copies 4130 (Lanxess), and stirred and mixed at a speed of 200 rpm, and then transferred to a horizontal sand mill, and ground until the color paste particle size reached 4, and then filtered to obtain a water-based inorganic yellow paste.

[0116] Example 10 (preparation of inorganic pigment paste using a dispersant having a block copolymer structure and a dispersing resin):

[0117] Step 1: Preparation of dispersant:

[0118] (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 51.6 g of MAA, and 106 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 2 hours. The structural formula of the precursor is: Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0119] (2) Add 10 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, and after nitrogen removal, react at 80 ° C for 12 hours;

[0120] (3) After cooling to room temperature, the dispersant was precipitated with cyclohexane as a precipitant, and the product was dried in vacuo. The molecular weight of the product was gradually increased with the addition of MAA and MMA monomers by GPC (gel permeation chromatography). The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The structural formula was measured to be:

[0121]

[0122] Among them, n1=5, n2=30.

[0123] Step 2: Preparation of inorganic pigment paste:

[0124] 28 parts of dispersing resin were added to the dispersing kettle, stirring was started, and the speed was maintained at 100 rpm. Then 14 parts of purified water, 0.01 parts of monoethanolamine (BASF), 3 parts of the above-mentioned dispersant with block copolymer structure of n1=5, n2=30, 0.06 parts of DF 3163 (Deqian Company) and 10 parts of iron oxide blue (Changzhou Fengshuo Chemical Co., Ltd.) were stirred and mixed at a rate of 200 rpm and then transferred to a horizontal sand mill. After grinding until the color paste particle size reached less than 300 nm (3 passes), the material was filtered out to obtain a water-based inorganic blue paste.

[0125] Example 11 (preparation of inorganic pigment paste using a dispersant and a dispersing resin having a random copolymer structure):

[0126] Step 1: Preparation of dispersant:

[0127] (1) 3 g of the precursor, 0.4 g of azobisisocyanovaleric acid initiator, 51.6 g of MAA, 10 g of MMA, and 138 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 12 hours. The structural formula of the precursor is:

[0128] Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0129] (2) Cooling to room temperature, using cyclohexane as a precipitant to precipitate the dispersant, and vacuum drying to obtain the dispersant having a random copolymer structure. The random copolymer structure dispersant obtained by vacuum drying was tested by GPC (gel permeation chromatography). The molecular weight of the dispersant increased once the mixed monomers of MAA and MMA were added. The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The measured structural formula was as follows:

[0130]

[0131] Among them, n1=5, n2=30.

[0132] Step 2: Preparation of inorganic pigment paste:

[0133] 28 parts of dispersion resin were added to the dispersion kettle, stirring was started, and the speed was maintained at 100 rpm. Then 14 parts of purified water, 0.01 parts of monoethanolamine (BASF), 3 parts of the above-mentioned dispersant with random copolymer structure of n1=5, n2=30, 0.06 parts of DF 3163 (Deqian Company) and 10 parts of iron oxide blue (Changzhou Fengshuo Chemical Co., Ltd.) were stirred and mixed at a speed of 200 rpm and then transferred to a horizontal sand mill. After grinding until the color paste particle size reached 4, the material was filtered and discharged to obtain a water-based inorganic blue paste.

[0134] Example 12 (preparation of inorganic pigment paste using a dispersant having a block copolymer structure and a dispersing resin):

[0135] Step 1: Preparation of dispersant:

[0136] (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 41.28 g of MAA, and 106 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 2 hours. The structural formula of the precursor is: Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0137] (2) Add 8 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, remove oxygen through nitrogen flow, and react at 80 ° C for 12 hours;

[0138] (3) After cooling to room temperature, the dispersant was precipitated with cyclohexane as a precipitant, and the product was dried in vacuo. The molecular weight of the product was gradually increased with the addition of MAA and MMA monomers by GPC (gel permeation chromatography). The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The structural formula was measured to be:

[0139]

[0140] Among them, n1=4, n2=24.

[0141] Step 2: Preparation of inorganic pigment paste:

[0142] 22 parts of dispersing resin were added to the dispersing kettle, stirring was started, and the speed was maintained at 100 rpm. Then 10 parts of purified water, 0.01 parts of monoethanolamine (BASF), 2 parts of the above-mentioned dispersant with block copolymer structure of n1=4, n2=24, 0.04 parts of DF 3163 (Deqian Company) and 10 parts of inorganic carbon black SPECIAL BLACK 4 (Degussa Company, Germany) were stirred and mixed at a rate of 200 rpm and then transferred to a horizontal sand mill. After grinding until the color paste particle size reached below 300 nm, the material was filtered and discharged to obtain a water-based inorganic black paste.

[0143] Example 13 (preparation of inorganic pigment paste using a dispersant and a dispersing resin having a random copolymer structure):

[0144] Step 1: Preparation of dispersant:

[0145] (1) 3 g of the precursor, 0.4 g of azobisisocyanovaleric acid initiator, 41.28 g of MAA, 8 g of MMA, and 138 g of dioxane were mixed, and after nitrogen removal, the mixture was reacted at 80° C. for 12 hours. The structural formula of the precursor is:

[0146] Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group;

[0147] (2) Cooling to room temperature, using cyclohexane as a precipitant to precipitate the dispersant, and vacuum drying to obtain the dispersant having a random copolymer structure. The random copolymer structure dispersant obtained by vacuum drying was tested by GPC (gel permeation chromatography). The molecular weight of the dispersant increased once the mixed monomers of MAA and MMA were added. The measured molecular weight was basically consistent with the designed molecular weight, and the controllability was good. The measured structural formula was as follows:

[0148]

[0149] Among them, n1=4, n2=24.

[0150] Step 2: Preparation of inorganic pigment paste:

[0151] 22 parts of dispersion resin were added to the dispersion kettle, stirring was started, and the speed was maintained at 100 rpm. Then 10 parts of purified water, 0.01 parts of monoethanolamine (BASF), 2 parts of the above-mentioned dispersant with random copolymer structure of n1=4, n2=24, 0.04 parts of DF 3163 (Deqian Company) and 10 parts of inorganic carbon black SPECIAL BLACK 4 (Degussa Company, Germany) were stirred and mixed at a rate of 200 rpm and then transferred to a horizontal sand mill. After grinding until the color paste particle size reached below 300 nm, the material was filtered and discharged to obtain a water-based inorganic black paste.

[0152] Table 3. Performance data of various examples

[0153]

[0154]

[0155] From Table 3 we can see that:

[0156] It can be seen from Examples 1, 3, 5 and 7 that the block copolymer and random copolymer dispersants prepared by the present invention have better dispersing, refining and stabilizing effects on inorganic red pigments than the system of conventional small molecule dispersants and pure dispersing resins.

[0157] From the comparative experiments of Example 1 and Example 2, Example 3 and Example 4, and Example 5 and Example 6, it can be seen that the dispersion resin prepared by the present invention has an obvious synergistic dispersion function for the inorganic red pigment, which helps to refine the particle size of the inorganic red pigment and improve the thermal storage stability; at the same time, from the comparative experiments of Example 3 and Example 4, and Example 5 and Example 6, it can be seen that the dispersion resin helps to improve the shear stability of the inorganic red pigment paste.

[0158] From the comparative experiments of Example 3 and Example 5, Example 3 and Example 4, and Example 5 and Example 6, it can be seen that the dispersant system using a block copolymer structure has better performance in all aspects than the dispersant system using a random copolymer structure, and the system using both a dispersant and a dispersing resin has better performance in all aspects than the system using a dispersant alone.

[0159] From the comparative experiments of Example 4 and Example 6, Example 8 and Example 9, Example 10 and Example 11, and Example 12 and Example 13, it can be seen that the system using a dispersant with a block copolymer structure plus a dispersing resin has better performance in all aspects than the system using a dispersant with a random copolymer structure plus a dispersing resin.

[0160] Examples 4, 8, 10, and 12 demonstrate that the preferred system of a block copolymer dispersant plus a dispersing resin is highly effective in dispersing inorganic red, yellow, blue, and black pigment pastes. The inorganic pigment pastes produced using this method exhibit fine initial particle size, low viscosity, excellent storage stability (minimal changes in particle size and viscosity before and after thermal storage), and superior shear resistance. They are promising intermediates for the formulation of highly weather-resistant inorganic gravure inks for automotive interior decorative films.

[0161] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An inorganic pigment paste, characterized in that: The raw materials include the following weight ratio: 10 parts of inorganic pigment, 22-28 parts of dispersing resin, 2-3 parts of dispersing agent, 0.01-0.03 parts of alkaline neutralizer, 0.04-0.06 parts of defoaming agent, and 10-14 parts of purified water; the dispersing resin is prepared by the following method: (1) Add 4g Emulsogen APS 100, 1.1g NE-10, and 3g n-butyl acrylate monomer to 90g pure water, stir at 800rpm and heat to 90℃, reduce the stirring speed to 300rpm, add potassium persulfate aqueous solution obtained by dissolving 0.3g potassium persulfate in 4g pure water, wait for the reaction system to emit blue light, then add 62g n-butyl acrylate monomer and potassium persulfate aqueous solution obtained by dissolving 2g potassium persulfate in 10g pure water, and add both at the same time, and the addition time is 7h; then reduce the temperature of the reaction system to 63℃, add 1.5g isopropanol, and then add 6g n-butyl acrylate monomer, 18g AC-76, 10g methyl methacrylate monomer, 0.8g isopropylbenzene hydroperoxide, 0.6g N,N-dimethyltoluidine, 2g The monomer addition phase was stirred at 250 rpm with NE-10, and the addition time was controlled to be 2 hours. 6.4 g of sodium bicarbonate aqueous solution obtained by dissolving 0.4 g of sodium bicarbonate in 6 g of pure water was added. The addition rate of the sodium bicarbonate aqueous solution was adjusted to maintain the pH value of the reaction system between 5.5 and 7.

5. After the monomer addition phase and the sodium bicarbonate aqueous solution were added, the mixture was stirred at room temperature for 1.5 hours. 2.08 g of tert-butyl hydroperoxide aqueous solution obtained by dissolving 0.08 g of tert-butyl hydroperoxide in 2 g of pure water was added. The mixture was stirred at room temperature for 10 minutes. 2.08 g of Rongalite aqueous solution obtained by dissolving 0.08 g of Rongalite in 2 g of pure water was added. The mixture was stirred at room temperature for 10 minutes. Finally, the mixture was cooled to room temperature and discharged to obtain a silicone acrylic emulsion. (2) Take 50g of the above-mentioned silicone acrylic emulsion and add it into a dispersion kettle, start stirring, add 30g of sodium silicate and 50 parts of silicon dioxide dispersion at a stirring speed of 200-300rpm, keep stirring for 0.5-1h, and then filter and discharge the material to obtain the dispersed resin; the silicon dioxide dispersion uses silicon dioxide with a particle size of ≤100nm, and the solid content of the silicon dioxide dispersion is 30%-50%.

2. The inorganic pigment paste according to claim 1, characterized in that The inorganic pigment is at least one of inorganic iron red pigment, iron oxide yellow, iron oxide blue, and inorganic carbon black.

3. The inorganic pigment paste according to claim 1, characterized in that The chemical structural formula of the dispersant is:

4. Among them, n1 is the degree of polymerization of the methyl methacrylate monomer unit, n1=3~5; n2 is the degree of polymerization of the methacrylic acid monomer unit, n2=22~30.

5. The inorganic pigment paste according to claim 3, characterized in that: n1=4, n2=24.

6. The inorganic pigment paste according to claim 3, characterized in that The dispersant is prepared by the following method: (1) 3 g of the precursor, 0.2 g of azobisisocyanovaleric acid initiator, 37.84-51.6 g of MAA, and 106 g of dioxane were mixed, and the mixture was reacted at 80 °C for 2 h after nitrogen removal. The structural formula of the precursor is: ; Wherein, Z is an alkylthio group having four carbon atoms, and X is an isopropanoyl group; (2) Add 6-10 g of MMA, 0.2 g of azobisisocyanovaleric acid initiator, and 32 g of dioxane, remove oxygen through nitrogen, and react at 80 °C for 12 hours; (3) Cool to room temperature, use cyclohexane as a precipitant to precipitate the dispersant, and vacuum dry to obtain the dispersant.

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