阅读说明：本技术 一种正电性彩色墨粉及其制备方法 (Electropositive color ink powder and preparation method thereof ) 是由 齐俊梅 王雪辉 姚雪丽 侯晓旭 陈辉辉 于 2021-01-18 设计创作，主要内容包括：本发明提供了一种正电性彩色墨粉及其制备方法,所述正电性彩色墨粉,包括如下重量份数的组分,聚酯树脂10～45份,苯丙树脂15～35份,蜡改性结晶聚酯16～40份,着色剂8～20份,正电性电荷调节剂1～4份,二氧化硅1～5份,二氧化钛1～6份该彩色墨粉具有良好的颜料分散性、着色力高,且具有较高的蜡含量,蜡在彩色墨粉中的分散性高,墨粉的低温定影性、脱模性优异。本发明彩色墨粉颗粒的球形度高,有较强的带电稳定性,可以提供精细的高品质彩色图像。(The invention provides an electropositive color toner and a preparation method thereof, wherein the electropositive color toner comprises the following components, by weight, 10-45 parts of polyester resin, 15-35 parts of styrene-acrylic resin, 16-40 parts of wax modified crystalline polyester, 8-20 parts of a coloring agent, 1-4 parts of an electropositive charge regulator, 1-5 parts of silicon dioxide and 1-6 parts of titanium dioxide, and the color toner has good pigment dispersibility and high tinting strength and has higher wax content, the dispersibility of wax in the color toner is high, and the low-temperature fixability and the demolding performance of the toner are excellent. The color toner particles of the present invention have high sphericity and high charging stability, and can provide fine high-quality color images.)

1. An electropositive color toner, characterized in that: the antistatic and antistatic coating comprises, by weight, 10-45 parts of polyester resin, 15-35 parts of styrene-acrylic resin, 16-40 parts of wax-modified crystalline polyester, 8-20 parts of a colorant, 1-4 parts of an electropositive charge regulator, 1-5 parts of silicon dioxide and 1-6 parts of titanium dioxide.

2. The electropositive color toner of claim 1 wherein: the antistatic coating comprises, by weight, 12-35 parts of polyester resin, 17-30 parts of styrene-acrylic resin, 20-38 parts of wax-modified crystalline polyester, 11-18 parts of a colorant, 1-3 parts of an electropositive charge regulator, 1-3 parts of silicon dioxide and 1-3 parts of titanium dioxide; preferably, the electropositive charge regulator comprises one of quaternary ammonium salts, alkoxylated amines, nigrosine compounds, or a combination thereof.

3. The electropositive color toner of claim 1 wherein: the polyester resin is a polyester resin with a high acid value of 16-30 mgKOH/g, preferably, the acid value is 18-25 mgKOH/g; preferably, the preparation of the polyester resin comprises the following steps of putting an acid component consisting of terephthalic acid and fumaric acid, an alcohol component consisting of bisphenol-A polyoxyethylene ether and ethylene glycol and a catalyst into a reaction kettle, reacting for 2-4 h at 200-230 ℃, vacuumizing to 1.5-2 kPa, continuing to react for 0.5-1 h, discharging, cooling and crushing into fine powder; preferably, the amount of the acid component is 40 to 70 mol%, and more preferably 45 to 60 mol% of the total components of the polyester resin; the fumaric acid accounts for 5 to 20 mol%, and more preferably 8 to 15 mol%, of the acid component.

4. The electropositive color toner of claim 1 wherein: the wax-modified crystalline polyester is obtained by polycondensation of a highly acidic wax having an acid content of more than 60mgKOH/g, an acid component comprising terephthalic acid and 1, 8-octanedioic acid, and an alcohol component comprising a saturated aliphatic diol having 2 to 6 carbon atoms; the mass fraction of the wax is 10-50%; preferably, the mass fraction is 12-25%.

5. The electropositive color toner of claim 1 wherein: the preparation method of the wax modified crystalline polyester comprises the following steps of putting high-acidity wax, terephthalic acid, an alcohol component and a catalyst into a reaction kettle, reacting at 150-160 ℃ for 1-2 h, then adding 1, 8-suberic acid, heating to 210-230 ℃, reacting for 2-4 h, vacuumizing to 0.5-1.5 kPa, continuing to react for 0.5-1 h, discharging, cooling to room temperature, crushing, fine powder and sieving to obtain the wax modified crystalline polyester; preferably, the catalyst accounts for 1-13% of the total mass of the acid component and the alcohol component; the high-acidity wax comprises one or more than two of montan wax, n-octacosanoic acid, palmitic acid and stearic acid, and the alcohol component comprises one or two of 1, 4-butanediol and 1, 6-hexanediol.

6. The electropositive color toner of claim 1 wherein: the silica has a BET value of less than 200m²A/g, preferably less than 150m²/g。

7. The electropositive color toner of claim 1 wherein: the titanium dioxide is subjected to organic surface treatment, preferably, the titanium dioxide is subjected to surface treatment by using an aminosilane hydrophobizing agent and has electropositivity, and preferably, the titanium dioxide is one or the combination of titanium dioxide products of TAYCA CORPORATION, JMT-150ANO, HMT-100WNS and MTY-700 NO.

8. The electropositive color toner of claim 1 wherein: the method comprises the following steps that (1) the surface of toner particles is subjected to spheroidization, and in the spheroidization process, the heat flow temperature is 250-350 ℃, preferably 260-300 ℃; the sphericity of the toner is controlled to 0.975 + -0.002.

9. The electropositive color toner of claim 1 wherein: the styrene-acrylic resin has an alkane-amino group, and is preferably obtained by copolymerization of styrene, acrylic ester and dimethylaminoethyl methacrylate; preferably, the preparation of the styrene-acrylic resin comprises the following steps of putting a solvent xylene into a reaction kettle, and heating to the reflux temperature of 135-140 ℃; uniformly mixing a reaction monomer consisting of styrene, acrylic ester and dimethylamino ethyl methacrylate, an initiator di-tert-butyl peroxide and a cross-linking agent divinylbenzene, dropwise adding the mixture into a reaction kettle at a constant speed for 2-4 hours, wherein the contents of the components are respectively as follows according to molar ratio: 40-70 mol% of styrene, 10-20 mol% of acrylate, 6-10 mol% of dimethylaminoethyl methacrylate, 1-3 mol% of di-tert-butyl peroxide and 1-3 mol% of divinylbenzene; and (3) continuously preserving the heat of the polymerization reaction for 2-4 h at the xylene reflux temperature, vacuumizing to 1.5kPa, removing the solvent, cooling, discharging, finely grinding and sieving to obtain the styrene-acrylic resin with the alkane-amino groups.

Technical Field

The invention belongs to the technical field of colored ink powder, and particularly relates to electropositive colored ink powder and a preparation method thereof.

Background

With the trend toward the digitization, high speed, and colorization of electrophotography and printing becoming more and more significant, the popularity of colorization has rapidly increased the amount of toner used for color development. The general quality requirements of color toners are uniform color, high circularity, and relatively small particle size to meet high resolution requirements.

In the electrostatic development system, the positively charged photosensitive drum generates less ozone than the negatively charged photosensitive drum, which is more beneficial to environmental protection. Recently, a plurality of electropositive color laser printers and copiers are on the market, and the market demand of electropositive color toner is increasing.

Polyester resins are particularly useful as resin binders for preparing color toners because they improve fixing properties, durability and transparency of color toners. However, since the polyester resin has a carboxyl group, it itself has electronegativity, thereby making it difficult to apply the polyester resin to an electropositive color toner. Polyester resins and styrene-acrylic resins having a low acid value can be used for preparing an electropositive toner, but cause poor chroma of printed images due to poor dispersibility thereof for pigments. The polyester resin having a high acid value can disperse the pigment in the color toner more uniformly because most pigments have polar functional groups, and the polar groups of the polyester resin species can give the resin and the organic pigment a better affinity, but the color toner containing the polyester having a high acid value has a poor charging stability in an environment with a high humidity.

Color development systems generally require higher wax content and higher wax dispersion requirements due to color requirements. The preparation method of the color toner is a traditional physical pulverization method and a chemical method. The physical crushing method is mainly applied to the preparation of black toner, the process is mature, the cost is low, but the mixing dispersibility of components such as pigment, wax, resin and the like is poor when the color toner is prepared, and the granularity of the crushed and classified toner particles is not uniform and the sphericity is not high (the sphericity is generally 0.92-0.94); in order to improve the sphericity of toner particles, a surface spheroidization process has been proposed, and a difficulty of the surface spheroidization treatment process is that toner particles are easily aggregated while passing through a high-temperature region, resulting in a decrease in the sphericity of toner and a change in the particle size distribution. The chemical method better solves the requirements of component dispersibility, particle size uniformity and high sphericity, but has the defects of higher research and development cost, large water consumption, complex environmental protection treatment and the like.

Disclosure of Invention

In view of the above, the present invention is directed to an electropositive color toner having good pigment dispersibility, high coloring power, and a high wax content, and having high wax dispersibility in the color toner and excellent low temperature fixability and mold release properties, and a method for preparing the same. The sphericity of the color toner particles can be controlled to be 0.975 +/-0.002, the color toner particles have stronger charging stability, and fine and high-quality color images can be provided.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the electropositive color ink powder comprises, by weight, 10-45 parts of polyester resin, 15-35 parts of styrene-acrylic resin, 16-40 parts of wax modified crystalline polyester, 8-20 parts of a colorant, 1-4 parts of an electropositive charge regulator, 1-5 parts of silicon dioxide and 1-6 parts of titanium dioxide.

Preferably, the antistatic coating comprises, by weight, 12-35 parts of polyester resin, 17-30 parts of styrene-acrylic resin, 20-38 parts of wax-modified crystalline polyester, 11-18 parts of a colorant, 1-3 parts of an electropositive charge regulator, 1-3 parts of silicon dioxide and 1-3 parts of titanium dioxide.

Preferably, the electropositive charge control agent comprises one or a combination of quaternary ammonium salts, alkoxylated amines, nigrosine compounds (e.g., nigrosine salts, or nigrosine derivatives).

The colorant is C, M, Y powder special blue, red 1, red 2, yellow organic pigment and K powder carbon black.

Preferably, the polyester resin is a polyester resin with a high acid value of 16-30 mgKOH/g, preferably, the acid value is 18-25 mgKOH/g; preferably, the preparation of the polyester resin comprises the following steps of putting an acid component consisting of terephthalic acid and fumaric acid, an alcohol component consisting of bisphenol-A polyoxyethylene ether and ethylene glycol and a catalyst into a reaction kettle, reacting for 2-4 h at 200-230 ℃, vacuumizing to 1.5-2 kPa, continuing to react for 0.5-1 h, discharging, cooling and crushing into fine powder; preferably, the amount of the acid component is 40 to 70 mol%, and more preferably 45 to 60 mol% of the total components of the polyester resin; the fumaric acid accounts for 5 to 20 mol%, and more preferably 8 to 15 mol%, of the acid component. The catalyst that can be used for preparing the polyester resin of the present invention may use a polycondensation catalyst known in the art. The catalyst comprises about 0.1 to 15%, preferably 1 to 5%, of the total mass of the acid component and the alcohol component.

Preferably, the wax-modified crystalline polyester is obtained by polycondensation of a highly acidic wax having an acid content of more than 60mgKOH/g, an acid component comprising terephthalic acid and 1, 8-octanedioic acid, and an alcohol component comprising a saturated aliphatic diol having 2 to 6 carbon atoms; the mass fraction of the wax is 10-50%; preferably, the mass fraction is 12-25%.

Preferably, the preparation of the wax modified crystalline polyester comprises the following steps of putting high-acidity wax, terephthalic acid, an alcohol component and a catalyst into a reaction kettle, reacting at 150-160 ℃ for 1-2 h, then adding 1, 8-suberic acid, heating to 210-230 ℃, reacting for 2-4 h, vacuumizing to 0.5-1.5 kPa, continuing to react for 0.5-1 h, discharging, cooling to room temperature, crushing, grinding into fine powder and sieving to obtain the wax modified crystalline polyester; preferably, the catalyst accounts for 1-13% of the total mass of the acid component and the alcohol component; the high-acidity wax comprises one or more than two of montan wax, n-octacosanoic acid, palmitic acid and stearic acid, and the alcohol component comprises one or two of 1, 4-butanediol and 1, 6-hexanediol.

Preferably, the silica has a BET value of less than 200m²A/g, preferably less than 150m²/g。

Preferably, the titanium dioxide is titanium dioxide subjected to organic surface treatment, preferably, the titanium dioxide is titanium dioxide subjected to surface treatment by an aminosilane hydrophobizing agent and provided with electropositivity, and preferably, the titanium dioxide is one or the combination of titanium dioxide products of TAYCA CORPORATION, JMT-150ANO, HMT-100WNS and MTY-700 NO.

Preferably, the ink powder particles are subjected to surface spheroidization, and in the spheroidization process, the heat flow temperature is 250-350 ℃, preferably 260-300 ℃; the sphericity of the toner is controlled to 0.975 + -0.002.

Preferably, the styrene-acrylic resin has an alkane-amino group, and is obtained by copolymerization of styrene, acrylate and dimethylaminoethyl methacrylate. The preparation method of the styrene-acrylic resin comprises the following steps of putting a solvent xylene into a reaction kettle, and heating to the reflux temperature of 135-140 ℃; uniformly mixing a reaction monomer consisting of styrene, acrylic ester and dimethylamino ethyl methacrylate, an initiator di-tert-butyl peroxide and a cross-linking agent divinylbenzene, dropwise adding the mixture into a reaction kettle at a constant speed for 2-4 hours, wherein the contents of the components are respectively as follows according to molar ratio: 40-70 mol% of styrene, 10-20 mol% of acrylate, 6-10 mol% of dimethylaminoethyl methacrylate, 1-3 mol% of di-tert-butyl peroxide and 1-3 mol% of divinylbenzene; and (3) continuously preserving the heat of the polymerization reaction for 2-4 h at the xylene reflux temperature, vacuumizing to 1.5kPa, removing the solvent, cooling, discharging, finely grinding and sieving to obtain the styrene-acrylic resin with the alkane-amino groups.

The preparation of the electropositive color toner includes the following steps,

(1) premixing: respectively weighing 10-45 parts of polyester resin, 15-35 parts of styrene-acrylic resin, 16-40 parts of wax modified crystalline polyester, 8-20 parts of coloring agent and 1-4 parts of positive charge regulator according to a proportion, putting the raw materials into a Henschel mixer together for mixing, firstly mixing at a low speed of 1000rpm for 60 seconds, and then mixing at a high speed of 4000rpm for 40 seconds;

(2) melting, mixing and extruding: melting and mixing the premixed materials through an extruder, extruding and tabletting through the extruder, and cooling;

(3) coarse crushing: feeding into a ball mill for coarse grinding, and grinding to obtain material with average particle diameter D₅₀Controlling the thickness to be 0.9-1.1 mm;

(4) airflow crushing and grading: placing the coarsely crushed material into a jet mill classifier for crushing, mainly controlling the content of large particles, and classifying to obtain a semi-finished product;

(5) grading the micro powder: carrying out micro powder classification on the crushed material, removing unqualified small particles, and enabling the average particle diameter D of the particles₅₀Controlling the particle size to be 5-10 micrometers, preferably 6-9 micrometers;

(6) mixing silicon dioxide: and putting the materials and 1-5 parts of external additive large-particle silicon dioxide weighed according to the weight percentage into a Henschel mixer for mixing. First 60 seconds at 1000rpm followed by 40 seconds at 4000 rpm.

(7) Spheroidizing: the toner particles mixed with silica as an external additive were subjected to surface spheroidization by a surface fusion system (manufacturer NPK, model MR-10). In the process of spheroidization, the filling rate is 3 +/-0.5 kg/h, the heat flow temperature is 250-350 ℃, preferably 260-300 ℃, and the sphericity of the ink powder is controlled to be 0.975 +/-0.002.

(8) Mixing titanium dioxide: the materials and 1-6 parts of titanium dioxide subjected to organic surface treatment weighed according to the weight ratio are put into a Henschel mixer together for mixing. First 60 seconds at 1000rpm followed by 40 seconds at 4000 rpm.

Compared with the prior art, the electropositive color toner and the preparation method thereof have the following advantages:

in the color toner, the polyester resin has a high acid value of 16-30 mgKOH/g, so that the pigment dispersibility and the tinting strength in the color toner can be improved; the styrene-acrylic resin has an alkane-amino group, and can provide high electropositivity; the wax modified crystalline polyester can enable the color toner to have higher wax content, improve the dispersibility and the mold release property of the wax in the color toner and improve the low-temperature fixing property of the toner. The hydrophobized titanium dioxide subjected to the organic surface treatment can impart electropositivity to the toner while improving the environmental stability and fluidity of the toner.

The preparation method of the color toner adopts the technical process of mixing silicon dioxide before surface spheroidization treatment, and the BET value of the silicon dioxide is less than 200m²A/g, preferably less than 150m²The/g can well play a role in spacing among the ink powder particles, the heat flow temperature in the surface spheroidization treatment is 250-350 ℃, the ink powder can be effectively prevented from being aggregated in the surface spheroidization treatment process, the sphericity of the obtained color ink powder particles is high, and the sphericity can be controlled to be 0.975 +/-0.002. The color toner has the advantages of uniform dispersion of components, strong positive electrification property, high electrification stability and capability of providing fine and high-quality images.

Detailed Description

Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.

The present invention will be described in detail with reference to examples.

The electropositive color toner of the embodiment of the invention comprises the following components in parts by weight, wherein each 1 part by weight is 1 kg.

The materials used in the examples and comparative examples are now described below, but are not limited to these materials:

the polyester resin is prepared by the following method: 2 mol of terephthalic acid, 0.3 mol of fumaric acid, 1 mol of bisphenol-A polyoxyethylene ether, 1.5 mol of ethylene glycol and a catalyst accounting for 1 percent of the total mass of the acid component and the alcohol component are put into a reaction kettle, the temperature is raised to 230 ℃, the reaction lasts for 2 hours, the vacuum pumping is carried out until the pressure reaches 1.5kPa, the reaction lasts for 0.5 hour, the materials are discharged, cooled and crushed into fine powder, and the acid value of the obtained polyester resin is 20 mgKOH/g.

The wax modified crystalline polyester is prepared by the following method: 0.5 mol of high-acidity wax, 1 mol of terephthalic acid, 0.3 mol of bisphenol-A polyoxyethylene ether, 1 mol of catalyst accounting for 1 percent of the total mass of ethylene glycol, acid components and alcohol components are put into a reaction kettle, 0.4 mol of 1, 8-suberic acid is put into the reaction kettle after the reaction is carried out for 1 to 2 hours at 150 ℃, the temperature is increased to 230 ℃, the reaction is carried out for 2 hours, the vacuum pumping is carried out to 1.5kPa, the reaction is continued for 0.5 hour, the discharging is carried out, the cooling is carried out to the room temperature, and the high-acidity wax is obtained by crushing, fine powder and sieving.

The styrene-acrylic resin is prepared by the following method: putting a solvent xylene into a reaction kettle, and heating to reflux temperature of 135-140 ℃. Uniformly mixing 2 moles of styrene, 0.5 mole of acrylate, 0.2 mole of dimethylaminoethyl methacrylate, 0.02 mole of di-tert-butyl peroxide and 0.02 mole of divinylbenzene, dropwise adding the mixture into a reaction kettle at a constant speed, and dropwise adding the mixture for 2 hours. And continuously preserving the heat of the polymerization reaction for 2 hours at the xylene reflux temperature, vacuumizing to 1.5kPa, removing the solvent, cooling, discharging, finely grinding and sieving to obtain the styrene-acrylic resin with the alkane-amino group.

The BET value of the silica used is less than 150m²/g。

The titanium dioxide is one of titanium dioxide subjected to organic surface treatment, preferably titanium dioxide subjected to surface treatment by aminosilane hydrophobizing agent and having electropositivity, and further preferably titanium dioxide products of TAYCA CORPORATION, such as JMT-150ANO, HMT-100WNS and MTY-700NO, or a combination thereof.

Unless otherwise specified, the technical means used in the examples of the present invention are conventional means well known to those skilled in the art.

The electropositive color toners described in examples 1 to 4 and comparative examples 1 to 3 below were prepared according to the formulations of Table 1 with reference to the following methods.

S1, respectively weighing polyester resin, styrene-acrylic resin, wax modified crystalline polyester, a coloring agent (product name: C44, manufactured by Mitsubishi chemical corporation) and an electropositive charge regulator (product name: quaternary ammonium salt P12, manufactured by Wuhandinglong chemical corporation) according to the proportion, putting the raw materials into a Henschel mixer together for mixing, firstly mixing at low speed of 1000rpm for 60 seconds, and then mixing at high speed of 4000rpm for 40 seconds;

s2, melting and mixing the premixed materials through an extruder, extruding and tabletting through the extruder, and cooling;

s3, inputting the materials into a ball mill for coarse crushing;

s4, placing the coarsely crushed material into a jet mill classifier for crushing, mainly controlling the content of large particles, and classifying to obtain a semi-finished product;

s5, carrying out micro powder classification on the crushed material, removing unqualified small particles, and controlling the average particle diameter D of the toner particles₅₀5-10 microns;

s6, putting the materials and the large-particle silicon dioxide external additive into a Henschel mixer for mixing. First 60 seconds at 1000rpm followed by 40 seconds at 4000 rpm.

S7, the toner particles mixed with silica as an external additive were subjected to surface spheroidization by a surface fusion system (manufacturer NPK, model MR-10). In the process of spheroidization, the filling rate is 3 +/-0.5 kg/h, and the heat flow temperature is controlled to be 250-350 ℃.

S8, putting the materials and titanium dioxide (model JMT-150ANO, manufacturer TAYCA CORPORATION) which is weighed according to the weight ratio and is subjected to organic surface treatment into a Henschel mixer for mixing. Firstly mixing at low speed of 1000rpm for 60 s, then mixing at high speed of 4000rpm for 40 s to obtain the product with sphericity of 0.975 + -0.002 and average particle diameter D₅₀6-8 microns is a finished product of the electropositive color ink powder.

TABLE 1 weight ratio formulation of components in inventive and comparative examples

Method for testing various performances

Charging property: the chargeability of the color ink powder product is measured by adopting a TREK (TREK attractive electron transfer tester) of America;

average particle diameter D₅₀: the particle size and the distribution of the color toner are measured by a Beckmann Coulter LS 13320 series laser particle size analyzer;

sphericity: measuring the sphericity of the colored toner particles by using a Zhuhai Europe and America graphic instrument;

softening point temperature: a flow tester (CFT-500D, Shimadzu Corp.);

fixation fastness: adopting a QEA image quality analysis system;

long-term storage stability: and observing whether the caking phenomenon appears after the storage is carried out for 18 months, wherein the measured standard is that the caking accounts for less than 1 percent of the mass ratio, a small amount is between 1 percent and 5 percent, and more than 5 percent is present.

Finished electropositive color toners prepared in examples 1 to 4 and comparative examples 1 to 3 were prepared under normal temperature and humidity conditions (25 ℃, 55% RH) using ISO/IEC 197 on a Brother HL5450DN (maximum printing breadth A4, printing speed 38ppm, maximum resolution 1200X 1200dpi)Standard 5% coverage monochrome printing 52 test pages 5000 pages were printed. The chargeability and average particle diameter D were measured by the methods described above₅₀Circularity, softening point temperature, fixing fastness, long-term storage stability, image density. The results of the performance tests of the color toner products prepared in the above examples and comparative examples are shown in Table 2 below.

TABLE 2 Performance test results of electropositive color toner products prepared in examples of the present invention and comparative examples

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.