Polyester resin emulsion, preparation method thereof, toner and application thereof

Abstract

The invention relates to a polyester resin emulsion which comprises polyester resin particles and an aqueous medium, the particle size of the polyester resin particles is 120-180 nm, and the particle size DPI is 0.01-0.30; the content of a ketone solvent in the polyester resin emulsion is 0.01-20 ppm, and the content of an alcohol solvent in the polyester resin emulsion is 0.01-25 ppm; the pH value of the polyester resin emulsion is 7-10, and the polyester resin emulsion does not contain an additional surfactant; the polyester resin comprises crystalline polyester resin or amorphous polyester resin, and the raw material of the amorphous polyester resin comprises at least one of tetrapropenyl succinic anhydride, octaalkenyl succinic anhydride, hexadecyl succinic anhydride and octadecenyl succinic anhydride. The toner prepared from the polyester resin emulsion has excellent fixability, charge stability and storage stability, the bottom ash phenomenon can be reduced, and the comprehensive developing performance of the toner can be improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic photographic toner technology, specifically relating to a polyester resin emulsion and its preparation method, as well as toners and their applications. Background Technology

[0002] The main components of polyester resin toners include amorphous binder resin, crystalline resin, colorant, wax, and additives. During preparation, the amorphous binder resin and crystalline resin need to be formulated into an emulsion for subsequent coagulation. However, removing polar solvents such as ketones (e.g., acetone, 2-butanone) and alcohols (e.g., ethanol, 2-propanol) from the polyester resin emulsion remains a challenge. Toners produced using traditional negative pressure desolventizing methods still retain 400–1000 ppm of ketones and 300–600 ppm of alcohols, severely affecting the charge uniformity and low-temperature fixing performance of the polyester toner. Furthermore, this leads to poor storage stability of the polyester toner and defects such as background graying and ghosting in printed products.

[0003] The production of low-solvent-residue polyester resin emulsions faces the following main challenges: Firstly, the characteristics of polyester resin lead to solvent residue, and the strong interaction between polyester resin and ketone and / or alcohol solvents makes it difficult to remove; secondly, process defects cause high viscosity of polyester resin solutions and low efficiency of traditional desolvation methods; existing adsorbents also have poor compatibility with polyester resin systems; in addition, repeated washing can damage the particle size structure and distribution of polyester resin microspheres.

[0004] Therefore, there is an urgent need to develop a polyester resin emulsion with low solvent residue to solve the above problems. Summary of the Invention

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, this application provides a polyester resin emulsion comprising polyester resin microparticles and an aqueous medium, wherein the polyester resin microparticles have a particle size of 120-180 nm and a particle size DPI of 0.01-0.30; the polyester resin emulsion contains 0.01-20 ppm of ketone solvents and 0.01-25 ppm of alcohol solvents; the polyester resin emulsion has a pH of 7-10 and does not contain any additional surfactants; the polyester resin comprises crystalline polyester resin or amorphous polyester resin, wherein the amorphous polyester resin raw material comprises at least one of tetrapropylene succinic anhydride, octaenyl succinic anhydride, hexadecenyl succinic anhydride, and octadecenyl succinic anhydride.

[0007] In some possible implementations, the glass transition temperature (Tg) of the amorphous polyester resin is 54-65 °C, preferably 56-60 °C.

[0008] In some possible embodiments, the melting temperature Tm of the crystalline polyester resin is 70~80 °C, preferably 72~78 °C.

[0009] Secondly, this application provides a method for preparing a polyester resin emulsion as provided in the first aspect of this application, characterized by comprising the following steps:

[0010] S1. Resin emulsification: Polyester resin is dissolved in ketone and alcohol solvents, ammonia is added to adjust the pH of the system to alkaline, pure water is slowly added dropwise to the resin solution, and the mixture is stirred and emulsified to obtain a primary emulsion;

[0011] S2. Initial solvent removal: The above primary emulsion is heated and vacuumed to reduce the content of ketone or alcohol solvents in the system to below 1000 ppm;

[0012] S3. Adsorption residue: Add a small amount of resin microspheres and stir thoroughly to reduce the content of residual ketone solvents in the system to 0.01~20 ppm and the content of residual alcohol solvents to 0.01~25 ppm;

[0013] S4. Solid-liquid separation: Centrifugation or filtration removes the resin microsphere-solvent complex to obtain a polyester resin emulsion.

[0014] In some possible implementations, the resin microspheres include at least one of polymethyl methacrylate, polystyrene, polyvinyl alcohol, and divinylbenzene.

[0015] In some possible implementations, the resin microspheres have a particle size of 50-500 nm, preferably 100-200 nm.

[0016] In some possible implementations, the resin microspheres have a specific surface area of ​​50-200 m² / g, preferably 60-100 m² / g.

[0017] In some possible implementations, the amount of resin microspheres added is 1 to 10 wt% of polyester resin microparticles.

[0018] Thirdly, this application provides a colorant prepared by agglomeration of the polyester resin emulsion, colorant dispersion and wax dispersion provided in the first aspect of this application.

[0019] Fourthly, this application provides the use of a toner, as provided in the third aspect of this application, in the field of electrophotography for printing or copying.

[0020] Beneficial effects:

[0021] 1. Introducing a double bond structure into the dicarboxylic acid of the non-crystalline polyester resin raw material can make the charge of the toner more stable, which helps to suppress the background gray problem and improve the development performance;

[0022] 2. Controlling the solvent residue in the polyester resin emulsion to a very low level helps improve the fixing properties, charge stability, and storage stability of the finished toner, reduces background graying, and improves the overall developing performance of the toner. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and not to limit the scope of the invention. Specific conditions not specified in the examples shall be carried out under conventional conditions or the manufacturer's recommended conditions. If the manufacturers of the reagents or instruments used are not specified, they can be conventional products that are commercially available or purchased.

[0024] It should be noted that the following embodiments are examples of this application and are used only to illustrate this application, and are not intended to limit this application. Other combinations and various modifications within the scope of this application are possible without departing from the spirit or scope of this application.

[0025] The following provides a detailed description of the polyester resin emulsion, its preparation method, and the colorant provided in this application.

[0026] <Polyester Resin Emulsion>

[0027] This embodiment provides a polyester resin emulsion comprising polyester resin particles and an aqueous medium.

[0028] Polyester resin microparticles

[0029] In this embodiment, the polyester resin microparticles have a particle size of 120-180 nm, preferably 140-160 nm, and a particle size DPI of 0.01-0.30. By ensuring that the particle size and distribution of the polyester resin microparticles are within the above range, a toner with a narrow particle size distribution can be obtained during subsequent toner preparation. This improves the dispersibility of other components in the toner, such as colorants, release agents, and charge regulators, resulting in more uniform toner components. Consequently, the development stability of the toner can be improved.

[0030] In this embodiment, the polyester resin includes crystalline polyester resin and amorphous polyester resin. Each resin is mainly composed of at least one dicarboxylic acid and at least one diol, and is obtained by polycondensation reaction under high temperature and negative pressure conditions in the presence of a catalyst.

[0031] In this embodiment, the dicarboxylic acid in the amorphous polyester resin raw material includes at least one of tetrapropylene succinic anhydride, octaenyl succinic anhydride, hexadecenyl succinic anhydride, and octadecenyl succinic anhydride. Introducing a double bond structure into the amorphous polyester resin raw material can make the charge of the final toner more stable, helping to suppress background graying and improve developing performance. Examples of diols used as amorphous polyester resin raw materials include bisphenol A, phthalic acid, terephthalic acid, 1,6-hexanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and neopentanediol; in this embodiment, bisphenol A is preferred.

[0032] In this embodiment, the glass transition temperature (Tg) of the amorphous polyester resin is 54~65 °C, preferably 56~60 °C. The dicarboxylic acid raw material for the amorphous polyester resin may also include aromatic dicarboxylic acids, such as phthalic acid, terephthalic acid, isophthalic acid, and 1,5-naphthalenedicarboxylic acid. By adjusting the relative content of the dicarboxylic acid and diol, the benzene ring content in the amorphous polyester resin is adjusted, thereby obtaining an amorphous polyester resin with an appropriate glass transition temperature, which is beneficial for improving the fixing performance of the toner.

[0033] In this embodiment, a crosslinking agent is also required during the preparation of the amorphous polyester resin to improve the degree of crosslinking of the polyester resin. Examples of crosslinking agents include ternary or higher-order carboxylic acids or anhydrides, such as trimellitic acid, trimellitic acid, trimellitic anhydride, oxaloylsuccinic acid, and trimalonic acid.

[0034] In this embodiment, the raw materials for the crystalline polyester resin are not particularly limited. Examples of dicarboxylic acids used as raw materials include aliphatic saturated dicarboxylic acids, aliphatic unsaturated dicarboxylic acids, and aromatic dicarboxylic acids. Examples of aliphatic saturated dicarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, and sebacic acid. Examples of aliphatic unsaturated dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, and itaconic acid. Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, and 1,5-naphthalenedicarboxylic acid. Examples of anhydrides for the various dicarboxylic acids include succinic anhydride, maleic anhydride, and phthalic anhydride.

[0035] Diols used as raw materials for crystalline polyester resins include aromatic diols, aliphatic diols, and alicyclic diols. Examples of aromatic diols include o-phthalimethanol, terephthalimethanol, isophthalimethanol, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A. Examples of aliphatic diols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, triethylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentanediol, dipropylene glycol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, and decanediol. Examples of alicyclic diols include dimethylolcyclohexane and hydrogenated bisphenol A.

[0036] In this embodiment, the melting temperature Tm of the crystalline polyester resin is 70~80 ℃, preferably 72~78 ℃. If the melting temperature Tm of the crystalline polyester resin is too high, it will lead to poor fixing. If the melting temperature Tm is too low, long-term storage or high temperature and high humidity environment will easily lead to particle deformation and agglomeration, affecting storage stability.

[0037] In this embodiment, deionized water is suitable as the aqueous medium, and the pH of the polyester resin emulsion is 7-10. No additional surfactant is added in this embodiment. Emulsification is achieved by the carboxyl groups of the polyester resin forming salts under alkaline conditions to create a bridging agent. The carboxyl groups react with ammonia to form ammonium carboxylate salts, which are hydrophilic, while the polymer chains are hydrophobic. This structure exhibits properties similar to surfactants, ensuring that the polyester resin solution forms stable emulsion particles in the aqueous phase. This avoids the need for additional surfactants during emulsification, which would make subsequent solvent removal difficult or incomplete. If the polyester resin emulsion is acidic, it will be difficult for the polyester resin to form salts for emulsification, resulting in an unstable emulsion structure and resin demulsification and precipitation.

[0038] Solvent residue

[0039] In this embodiment, the residual content of ketone solvents in the polyester resin emulsion is 0.01~20 ppm, and the residual content of alcohol solvents is 0.01~25 ppm. In the process of preparing toners by chemical coagulation, the residual solvents in the polyester resin emulsion directly affect the application performance of the final toner product.

[0040] On the one hand, residual solvents act as plasticizers in the resin, increasing the distance between molecular chains and weakening the intermolecular forces. This causes the polyester resin to soften and melt at lower temperatures, resulting in a lower measured Tg. However, in practical applications, the residual small-molecule solvents evaporate at high temperatures, actually "carrying away" some of the plasticizing effect. This means the resin requires higher temperatures and energy to completely melt during fixing, and cannot completely melt on the printer's fixing unit (heat roller), leading to problems such as poor fixing and easily erased images.

[0041] On the other hand, the charging of toner is mainly achieved through triboelectric charging. Residual solvent molecules will be distributed on the surface and inside of toner particles. Low molecular weight polar solvent molecules will affect the distribution and effectiveness of charge on the surface of toner particles. In fact, the solvent itself may contain or decompose to produce ionic substances, which will interfere with the normal charge exchange process, resulting in unstable charge of the toner, with the charge being too low or too high. Ultimately, this will lead to problems such as gray background (dirty background) and uneven image density in the printed matter.

[0042] In addition, residual solvents can affect the storage stability of toners, especially when the storage environment temperature is high. This can cause the surface of the resin particles to become slightly sticky and softened, which may cause the toner particles to stick together in the packaging or toner hopper, forming hard lumps. This can lead to poor toner dispensing or even complete blockage, preventing the toner from passing smoothly through the toner supply system and affecting the stability of the development process.

[0043] In this embodiment, the crystalline polyester resin emulsion or amorphous polyester resin emulsion, which is the main raw material of the toner, has extremely low solvent residue, which can significantly reduce the solvent residue in the finished toner and ultimately improve many problems such as poor development or poor storage stability of the toner caused by solvent residue.

[0044] <Preparation Method of Polyester Resin Emulsion>

[0045] This embodiment provides a method for preparing the above-mentioned polyester resin emulsion, which mainly includes the following steps:

[0046] S1. Resin emulsification: Dissolve the above-mentioned crystalline polyester resin or amorphous polyester resin in ketone and alcohol solvents, add alkaline reagents to adjust the pH of the system to alkaline, slowly add deionized water dropwise into the resin solution, and stir to emulsify to obtain a primary emulsion.

[0047] In this embodiment, ketone solvents are good solvents for polyester resins, while alcohol solvents are poor solvents. Therefore, the particle size and distribution of polyester resin particles depend on the relative content of ketone and alcohol solvents. The higher the content of ketone solvents, the smaller the particle size and the narrower the particle size distribution.

[0048] In this embodiment, the amount of deionized water added depends on the amount of resin solution. To ensure complete emulsification of the polyester resin, the amount of deionized water should be greater than the amount of resin solution. Preferably, the mass ratio of deionized water to resin solution is 1:1 to 10:1.

[0049] S2. Initial solvent removal: The above primary emulsion is heated and vacuumed to remove most of the ketone and alcohol solvents.

[0050] In this embodiment, before adding resin microspheres for adsorption, most of the ketone and alcohol solvents are initially removed under vacuum conditions of 50~80 °C and -0.08~-0.1 MPa.

[0051] S3. Adsorption Residue: Add a small amount of resin microspheres and stir for 1-3 hours to remove the remaining free solvent molecules in the adsorption system.

[0052] In this embodiment, the resin microspheres are polar, enabling them to interact with ketones or alcohols via dipole-dipole interactions. Their porous surface structure ensures adsorption of large amounts of solvent, allowing for significant solvent residue removal with only a small amount of resin microspheres. This is particularly effective for removing trace amounts of solvent below 100 ppm. Examples of resin microspheres include one or more combinations of polymethyl methacrylate (PMMA), polystyrene, polyvinyl alcohol, and divinylbenzene. Further, in this embodiment, polymethyl methacrylate (PMMA) is preferred.

[0053] In this embodiment, the resin microspheres have a particle size of 50-500 nm, preferably 100-200 nm, and a specific surface area of ​​50-200 m² / g, preferably 60-100 m² / g. If the resin microsphere particle size is greater than 500 nm, the specific surface area decreases, leading to poorer adsorption performance and even adsorption of emulsion particles, resulting in incomplete removal of solvent residues. If the resin microsphere particle size is less than 50 nm, the specific surface area is large, but the cost is high, making it unsuitable for industrial mass production.

[0054] In this embodiment, the amount of resin microspheres added is 1 to 10 wt% of the crystalline polyester resin or amorphous polyester resin mentioned above. Adding too much resin microspheres will hinder process stirring, causing serious foaming of the system and material waste; adding too little may result in incomplete removal of solvent residue.

[0055] S4. Solid-liquid separation: Centrifugation or filtration removes the resin microsphere-solvent complex to obtain a polyester resin emulsion.

[0056] In this embodiment, after removing the resin microsphere-solvent complex by centrifugation or filtration, the solvent residue in the system is detected. Once the content of ketone solvent is 0.01~20 ppm and the content of alcohol solvent is 0.01~25 ppm, the polyester resin emulsion is obtained.

[0057] <Toner>

[0058] The toner in this embodiment is prepared by agglomeration of the aforementioned polyester resin emulsion, colorant dispersion, and wax dispersion. Specifically, an amorphous polyester resin emulsion is mixed and stirred with an emulsion containing crystalline polyester resin, then the colorant dispersion and wax dispersion are added and mixed evenly. A surfactant is then added, and the mixture is heated and stirred until spheroidized to obtain the toner matrix. The toner matrix is ​​then filtered, washed with water, dried, and mixed with additives to obtain the toner.

[0059] The crystalline polyester resin emulsion and amorphous polyester resin emulsion used in this embodiment have extremely low solvent residue, small particle size, and uniform distribution. During the coagulation process, no additional organic solvent residue is introduced, which can significantly reduce the solvent residue of the toner product, improve fixing properties, charge stability, and storage stability, and reduce the phenomenon of under-gray.

[0060] In this embodiment, the wax dispersion is a dispersion made of wax, and the amount of wax used accounts for 1% to 15% of the total mass of the colorant, preferably 3% to 10%. The wax used can be a hydrocarbon wax such as low molecular weight polyethylene wax, maleic anhydride modified polyethylene wax, low molecular weight polypropylene wax, low molecular weight copolyolefin wax, paraffin wax, oxidized paraffin wax, microcrystalline wax, docosanoic acid docosyl ester, stearate octadecyl ester, carnauba wax, beeswax, or other natural waxes, or higher fatty acid amides such as oleamide and stearamide.

[0061] In this embodiment, the colorant dispersion is a dispersion made of colorant, and the amount of colorant used accounts for 3% to 12% of the total mass of the colorant, preferably 5% to 8%. Examples of colorants include cyan colorants, such as Pigment Blue 15:3, Pigment Blue 15:4, etc.; yellow colorants, such as Pigment Yellow 74, Pigment Yellow 93, Pigment Yellow 94, Pigment Yellow 155, etc.; magenta colorants, such as Pigment Red 31, Pigment Red 122, Pigment Red 150, Pigment Red 184, etc.; and black colorants, such as carbon black, magnetite, etc.

[0062] In this embodiment, the surface additive is externally added to the surface of the colorant matrix particles. The amount of surface additive is 1% to 5% based on the weight of polyester resin. The components of the surface additive include, but are not limited to, one or more of the following: titanium dioxide, aluminum oxide and other metal oxides, stearates, etc. Examples include: R972, R974, RY200, RX200, RA200, R202, R805, R812S, T805, TG-308, TG-811F, NY50, RY50, NAX50, RX50, RY51, TG-413, TG-390.

[0063] In this embodiment, other external additives, such as release agents and charge regulators, may be added to the colorant without compromising the effectiveness of the invention.

[0064] Example

[0065] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be construed as specific limitations thereof.

[0066] The raw materials used in the examples were all commercially available bulk industrial products, and the manufacturers included BASF, Wanhua Chemical, Asahikawa Chemical, and Huafeng.

[0067] Synthesis example 1

[0068] Amorphous polyester resin A-1

[0069] Two moles of bisphenol A, one mole of terephthalic acid, one mole of octaenyl succinic anhydride, 0.1 moles of trimellitic acid (TMA), and 0.01 moles of the catalyst dibutyltin laurylate (DBTL) were added to a reaction vessel and polycondensed at 180°C for 7 h, followed by polycondensation under a vacuum of -0.09 MPa for 2 h to obtain amorphous polyester resin A-1.

[0070] The glass transition temperature Tg, determined by DSC, is 58.7 ℃.

[0071] Synthesis example 2

[0072] Amorphous polyester resin A-2

[0073] Two moles of bisphenol A, 0.5 moles of terephthalic acid, 1.5 moles of hexadecenylsuccinic anhydride, 0.1 moles of trimellitic acid (TMA), and 0.01 moles of the catalyst dibutyltin laurylate (DBTL) were added to a reaction vessel and polycondensed at 180 °C for 7 h, followed by polycondensation under a vacuum of -0.09 MPa for 2 h to obtain amorphous polyester resin A-2.

[0074] The melting temperature Tg of the non-crystalline polyester resin A-2 was determined to be 66.4 ℃ by DSC.

[0075] Synthesis example 3

[0076] Crystalline polyester resin B-1

[0077] One mole of adipic acid, one mole of decanediol, and 0.01 mole of the catalyst dibutyltin lauryl laurate (DBTL) were added to the reaction vessel, and polycondensed at 150 °C for 3 h, followed by polycondensation under a vacuum of -0.09 MPa for 2 h.

[0078] The melting temperature Tm of crystalline polyester resin B-1 was determined to be 73.6 ℃ by DSC.

[0079] Comparative Synthesis Example 1

[0080] Amorphous polyester resin A'-1

[0081] Two moles of bisphenol A, one mole of terephthalic acid, one mole of succinic anhydride, 0.1 moles of trimellitic acid (TMA), and 0.01 moles of the catalyst dibutyltin laurylate (DBTL) were added to a reaction vessel and polycondensed at 180 °C for 7 h, followed by polycondensation under a vacuum of -0.09 MPa for 2 h to obtain amorphous polyester resin A'-1.

[0082] The glass transition temperature Tg, as determined by DSC, is 61.3 ℃.

[0083] Preparation Example 1

[0084] Non-crystalline polyester resin emulsion C-1

[0085] Take 500 g of the above-mentioned amorphous polyester resin A-1 into a reaction vessel, add 500 g of acetone and 50 g of methanol, heat to 80 ℃ and stir to dissolve, then add 10% potassium hydroxide solution to adjust the pH of the system to alkaline, keep warm for 0.5 h, and then add 2.5 L of water dropwise into the reaction vessel to obtain primary emulsion C-1. The obtained primary emulsion C-1 is subjected to preliminary solvent removal at 80 ℃ and -0.08 MPa vacuum for 2 h, then PMMA microspheres (particle size 100 nm, specific surface area 100 m² / g) with a relative mass fraction of 8 wt% of amorphous polyester resin A-1 are added, stirred for 2 hours, and filtered to obtain crystalline polyester resin emulsion C-1.

[0086] Preparation Examples 2-10

[0087] The preparation methods for amorphous polyester resin emulsions C-2 to C-8 and crystalline polyester resin emulsions D-1 to D-2 are the same as in Preparation Example 1, except for the solvents used and the types, particle sizes, specific surface areas, and contents of the resin microspheres. Other specific differences are shown in Table 1. In Preparation Example 6, the solvents used were 400 g of acetone and 150 g of methanol, and everything else was the same as in Preparation Example 1.

[0088] Comparative preparation examples 1-3

[0089] Comparative Preparation Example 1, amorphous polyester resin emulsion C'-1, used amorphous polyester resin A'-1 as raw material. Comparative Preparation Example 2 did not add resin microspheres to further remove solvent residue. Comparative Preparation Example 3 added 10% hydrochloric acid solution to adjust the pH of the system to acidic, as shown in Table 1.

[0090] Table 1

[0091] Polyester resin emulsion Polyester resin solvent Specific substances of resin microspheres Resin microsphere particle size (nm) Specific surface area of ​​resin microspheres (m² / g) Resin microsphere content (wt%) Preparation Example 1 C-1 A-1 Acetone + Methanol PMMA 100 100 5 Preparation Example 2 C-2 A-1 Acetone + Methanol polystyrene 100 100 5 Preparation Example 3 C-3 A-1 Cyclohexanone + n-Propanol PMMA 250 60 10 Preparation Example 4 C-4 A-1 Cyclohexanone + n-Propanol PMMA 500 40 3 Preparation Example 5 C-5 A-1 2-Butanone + Ethanol PMMA 250 60 10 Preparation Example 6 C-6 A-1 Acetone + Methanol PMMA 100 100 5 Preparation Example 7 C-7 A-2 Acetone + Methanol PMMA 100 100 5 Preparation Example 8 C-8 A-2 Cyclohexanone + n-Propanol PMMA 550 45 11 Preparation Example 9 D-1 B-1 Cyclohexanone + n-Propanol PMMA 250 60 10 Preparation Example 10 D-2 B-1 Cyclohexanone + n-Propanol Polyvinyl alcohol 100 100 5 Comparative Preparation Example 1 C’-1 A’-1 Acetone + Methanol PMMA 100 100 5 Comparative Preparation Example 2 C’-2 A-1 Acetone + Methanol / / / / Comparative preparation example 3 C’-3 A-1 Acetone + Methanol PMMA 100 100 5

[0092] The particle size and distribution, and solvent residue properties of the polyester resin emulsions prepared in Preparation Examples 1-10 and Comparative Preparation Examples 1-3 were determined and evaluated according to the following methods.

[0093] Evaluation of particle size and particle size distribution

[0094] The particle size and particle size distribution of polyester resin emulsion were tested using a Malvern Zetesizer Pro particle size analyzer.

[0095] Solvent Residue Evaluation

[0096] The solvent residue in polyester resin emulsions was tested using gas chromatography with a Thermo Fisher GC1600.

[0097] The evaluation results of preparation examples 1-10 and comparative preparation examples 1-3 are shown in Table 2.

[0098] Table 2

[0099] Polyester resin emulsion Particle size (nm) PDI Ketone solvent residue (ppm) Alcohol solvent residue (ppm) pH Preparation Example 1 C-1 121.1 0.020 0.5 1.7 8 Preparation Example 2 C-2 125.9 0.045 2.86 2.77 8 Preparation Example 3 C-3 126.8 0.030 5.64 6.94 8 Preparation Example 4 C-4 131.2 0.161 8.11 4.25 8 Preparation Example 5 C-5 124.5 0.141 7.86 10.67 8 Preparation Example 6 C-6 152.6 0.214 6.64 8.31 8 Preparation Example 7 C-7 129.3 0.084 11.64 15.34 9 Preparation Example 8 C-8 142.4 0.137 15.24 20.53 8 Preparation Example 9 D-1 133.3 0.081 5.33 6.75 8 Preparation Example 10 D-2 131.1 0.067 4.23 6.11 10 Comparative Preparation Example 1 C’-1 136.2 0.156 4.62 9.35 8 Comparative Preparation Example 2 C’-2 132.2 0.141 783.6 527.1 8 Comparative preparation example 3 C’-3 precipitation precipitation 8.34 13.52 6

[0100] Example 1

[0101] Toner E-1

[0102] Amorphous polyester resin emulsion C-1, crystalline polyester resin emulsion D-1, pigment red 31 dispersion, and oxidized paraffin dispersion were added to the coagulation system. The pH was adjusted to 3.5-4.0 under the action of potassium persulfate or ammonium persulfate. The temperature was slowly raised to 70-80 ℃ and kept at that temperature for 1-2 hours. Then the temperature was lowered to 50-60 ℃ and kept at that temperature for 2-3 hours. After cooling to room temperature, the toner matrix particles were obtained after washing and drying. After adding hydrophobically treated silica particles as an external additive, toner E-1 was obtained.

[0103] Examples 2-9

[0104] Toners E-2 to E-9

[0105] The methods for preparing the toners in Examples 2-9 are the same as those in Example 1, except that the components of the crystalline polyester resin emulsion and the amorphous polyester resin emulsion are different, and other conditions remain unchanged, as shown in Table 3.

[0106] Comparative Examples 1-2

[0107] Toners E'-1 to E'-2

[0108] The preparation methods of the toners in Comparative Examples 1 and 2 are the same as those in Example 1, except that the components of the crystalline polyester resin emulsion and the amorphous polyester resin emulsion are different, and other conditions remain unchanged, as shown in Table 3.

[0109] The developing properties of the toners prepared in the examples and comparative examples were measured and evaluated according to the following methods.

[0110] Fixing performance evaluation

[0111] The toner was installed on a modified version of a commercially available digital full-color printer (IMAGIO Neo C455). Solid circle images were printed in monochrome mode. The images were wiped five times with a load of 4.9 kPa. The relative density of the solid circle images before and after wiping was measured using a spectrophotometer (model: 528, manufacturer: X-Rite, USA). The ratio of the relative density of the solid circle images before and after wiping (after wiping / before wiping) was defined as the fixing firmness. The fixing firmness was evaluated according to the following standards:

[0112] A: Excellent (fixing fastness greater than or equal to 99%), no problem in practical use;

[0113] B: Good (fixing fastness greater than or equal to 98% but less than 99%), no problem in practical use;

[0114] C: Generally speaking (fixing fastness greater than or equal to 95% and less than 98%), there are no problems in practical use;

[0115] D: Poor (fixing fastness less than 95%), which has practical problems.

[0116] Base gray evaluation

[0117] The relative density of the printed image, measured using a spectrophotometer (model: 528, manufacturer: X-Rite, USA) relative to a white background area (image density: 0.00), is the background gray. The background gray is evaluated according to the following standards:

[0118] A: Very good (less than or equal to 0.005), no problem in practical use;

[0119] B: Good (greater than 0.005 and less than or equal to 0.008), no problem in practical use;

[0120] C: Generally (greater than 0.008 and less than or equal to 0.010), there are no problems in practical applications;

[0121] D: Poor (greater than 0.010), has practical problems.

[0122] Battery life stability evaluation

[0123] The toner was installed on a modified version of a commercially available digital full-color printer (IMAGIO Neo C455), and 100,000 images of charts at 50% of their original size were run in monochrome mode for evaluation. Based on the change in toner charge after the run, the charge stability was evaluated according to the following standards:

[0124] A: The change in charge is less than 4 μC / g;

[0125] B: The change in charge is greater than 4 μC / g and less than or equal to 10 μC / g;

[0126] C: The change in charge exceeds 10 μC / g.

[0127] Storage stability evaluation

[0128] Place 10 g of toner into an open, round container and leave it at 50°C and 60% humidity for 72 hours. Then, gently transfer it to the container holding the toner and visually inspect it for any agglomeration. No agglomeration is observed on the surface of the toner, indicating excellent shelf life. If agglomeration occurs but can be eliminated without vibration during transfer and does not affect the actual printing effect, it indicates good shelf life. If agglomeration does not disappear with vibration during transfer, it indicates poor shelf life.

[0129] Table 3

[0130] Toner Amorphous polyester resin emulsion Crystalline polyester resin emulsion Fixing performance evaluation Base gray evaluation Electrical stability evaluation Storage stability evaluation Example 1 E-1 C-1 D-1 A A A excellent Example 2 E-2 C-2 D-1 A A A excellent Example 3 E-3 C-3 D-1 A A A excellent Example 4 E-4 C-4 D-1 A A A excellent Example 5 E-5 C-5 D-1 A A A excellent Example 6 E-6 C-6 D-1 A A A excellent Example 7 E-7 C-7 D-1 A A A excellent Example 8 E-8 C-8 D-1 B A A good Example 9 E-9 C-1 D-2 A A A excellent Comparative Example 1 E’-1 C’-1 D-1 C D C Poor Comparative Example 2 E’-2 C’-2 D-1 D D C Poor

[0131] It should be noted that, based on the explanations and descriptions in the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and alterations to the present invention should also be within the scope of protection of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the invention.

Claims

1. A polyester resin emulsion, characterized in that, The mixture comprises polyester resin microparticles and an aqueous medium. The polyester resin microparticles have a particle size of 120-180 nm and a particle size DPI of 0.01-0.

30. The polyester resin emulsion contains 0.01-20 ppm of ketone solvents and 0.01-25 ppm of alcohol solvents. The polyester resin emulsion has a pH of 7-10 and does not contain any added surfactants. The polyester resin comprises crystalline polyester resin or amorphous polyester resin. The amorphous polyester resin raw material comprises at least one of butenyl succinic anhydride, octenyl succinic anhydride, hexadecenyl succinic anhydride, and octadecenyl succinic anhydride.

2. The polyester resin emulsion according to claim 1, characterized in that, The glass transition temperature (Tg) of the amorphous polyester resin is 54~65 ℃, preferably 56~60 ℃.

3. The polyester resin emulsion according to claim 1, characterized in that, The melting temperature Tm of the crystalline polyester resin is 70~80 ℃, preferably 72~78 ℃.

4. A method for preparing a polyester resin emulsion as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Resin emulsification: Polyester resin is dissolved in ketone and alcohol solvents, ammonia is added to adjust the pH of the system to alkaline, pure water is slowly added dropwise to the resin solution, and the mixture is stirred and emulsified to obtain a primary emulsion; S2. Initial solvent removal: The above primary emulsion is heated and vacuumed to reduce the content of ketone or alcohol solvents in the system to below 1000 ppm; S3. Adsorption residue: Add a small amount of resin microspheres and stir thoroughly to reduce the content of residual ketone solvents in the system to 0.01~20 ppm and the content of residual alcohol solvents to 0.01~25 ppm; S4. Solid-liquid separation: Centrifugation or filtration removes the resin microsphere-solvent complex to obtain a polyester resin emulsion.

5. The method for preparing the polyester resin emulsion according to claim 4, characterized in that, The resin microspheres include at least one of polymethyl methacrylate, polystyrene, polyvinyl alcohol, and divinylbenzene.

6. The method for preparing the polyester resin emulsion according to claim 4, characterized in that, The resin microspheres have a particle size of 50-500 nm, preferably 100-200 nm.

7. The method for preparing the polyester resin emulsion according to claim 4, characterized in that, The resin microspheres have a specific surface area of ​​50~200 m² / g, preferably 60~100 m² / g.

8. The method for preparing the polyester resin emulsion according to claim 4, characterized in that, The amount of resin microspheres added is 1 to 10 wt% of polyester resin microparticles.

9. A toner, characterized in that, It is prepared by agglomeration of the polyester resin emulsion, colorant dispersion and wax dispersion as described in any one of claims 1 to 3.

10. A toner as described in claim 9 applied to electrophotography for printing or copying.