Styrene-acrylate-epoxy graft copolymer for toner and preparation method thereof

Abstract

This application relates to the field of binder resins for toners, specifically disclosing a styrene-acrylate-epoxy graft copolymer for toners and its preparation method. The styrene-acrylate-epoxy graft copolymer for toners is copolymerized from the following components: 40-60 wt% styrene monomer, 30-50 wt% acrylate monomer, and 5-15 wt% epoxy group-containing monomer. The copolymer has a molecular weight of 20,000-50,000, a glass transition temperature of 50-70°C, a softening point of 90-120°C, and an epoxy group content of 3-10%. This copolymer exhibits excellent low-temperature fixing and low thermal offset performance.

Description

Technical Field

[0001] The present application relates to the field of binder resins for toners, and more specifically, to a styrene-acrylate-epoxy graft copolymer for toners and a preparation method thereof. Background Art

[0002] Toner (also known as carbon powder) is a powdered substance used in laser printers and copiers to create images on paper. It primarily consists of a binder resin, a colorant (such as carbon black), a charge control agent, and external additives. The binder resin typically accounts for 80%-90% of the toner's total weight, and its properties directly determine key toner characteristics such as fixing properties, charging performance, flowability, and storage stability. Toner binder resins must typically meet the following basic requirements: rapid melting and bonding to paper during heating; rapid solidification after removal from high temperatures to ensure image clarity; appropriate viscoelasticity and anti-offset properties to prevent image blur; and good pulverization performance. As office automation equipment continues to move toward higher speeds, smaller sizes, and greater energy efficiency, the market is placing stricter demands on toner binder resins for low-temperature fixing performance, requiring them to melt at relatively low temperatures and solidify quickly.

[0003] Styrene-acrylic acid copolymers are currently the most widely used toner binder resins. Their synthesis process is mature, cost-effective, and the resin's glass transition temperature and softening point can be controlled by adjusting the ratio of styrene to acrylate monomers. However, styrene-acrylic acid copolymers have significant deficiencies in low-temperature fixing performance, making them difficult to meet the energy-saving requirements of modern high-speed printing equipment.

[0004] In view of this, this application is filed. Summary of the Invention

[0005] The first object of the present application is to provide a styrene-acrylate-epoxy graft copolymer for toner.

[0006] The second object of the present application is to provide a method for preparing a styrene-acrylate-epoxy graft copolymer for toner.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect of the present application, a styrene-acrylate-epoxy graft copolymer for toner is provided, which is copolymerized from the following components:

[0009] 40-60wt% styrene monomer,

[0010] 30-50wt% of acrylic acid ester monomer,

[0011] 5-15 wt% of an epoxy group-containing monomer;

[0012] The copolymer has a molecular weight of 20,000-50,000, a glass transition temperature of 50-70° C., a softening point of 90-120° C., and an epoxy group content of 3-10%.

[0013] By adopting the above technical solution, the styrene-acrylate-epoxy graft copolymer combines the easy processability of styrene-acrylate, the low-temperature fixing property of polyester, and the high bonding strength of epoxy resin, so that the resin copolymer has excellent low-temperature fixing performance, good crushing characteristics, and stable charging performance; the styrene monomer can provide a rigid skeleton for the copolymer, maintain the mechanical strength and glass transition temperature of the resin, and prevent toner from agglomerating during storage; the acrylate monomer reduces the melt viscosity through the long-chain alkyl group, significantly improving the low-temperature fixing performance; the epoxy group monomer enhances the bonding strength and heat resistance through ring-opening crosslinking, reducing the thermal offset phenomenon during the fixing process, and realizes the synergistic effect of the styrene rigid chain segment, the acrylate flexible chain segment, and the epoxy reactive group, so that the copolymer has excellent low-temperature fixing performance, good crushing characteristics, and stable charging performance;

[0014] By limiting the mass fraction of styrene monomers, the copolymer has better mechanical properties, low-temperature fixing properties and anti-offset properties. By controlling the mass fraction of styrene monomers at 40-60%, the copolymer has better rigidity, is easier to crush, and improves processing performance, while avoiding the possibility of poor low-temperature fixing properties due to excessively high melting temperature; by controlling the mass fraction of acrylate monomers at 30-50%, the copolymer has better flexibility, which helps to improve fixing efficiency, and the copolymer has a suitable viscosity, giving it better anti-offset properties; by controlling the mass fraction of epoxy reactive groups, the copolymer has a suitable cross-linking density, avoiding the possibility of a decrease in bonding strength due to insufficient cross-linking density, and avoiding the possibility of excessive cross-linking of the bonding resin, deterioration of crushing performance, and poor processing performance due to excessively high proportion of reactive groups.

[0015] Preferably, the styrene monomer is styrene and a hydroxyl-containing styrene derivative in a mass ratio of (9-7):(3-1).

[0016] Preferably, the acrylic acid ester monomers are hydroxypropyl acrylate, branched alkyl acrylate and tetrahydrofuran ring-containing acrylic acid ester monomers in a mass ratio of 1:(6-8):(1-3).

[0017] Preferably, the epoxy group-containing monomer is glycidyl methacrylate and allyl glycidyl ether in a mass ratio of (9-8):(2-1).

[0018] By adopting the above technical solution, the present application achieves improvements in low-temperature fixing, high adhesion, and heat and wear resistance by optimizing the formula of each monomer and resin.

[0019] By copolymerizing styrene with hydroxyl-containing styrene derivatives, hydroxyl reaction sites are introduced while ensuring the solid-state stability of the resin. This enables the styrene rigid skeleton to form a reactive cross-linking network with epoxy groups and hydroxypropyl acrylate, which is beneficial for improving the stability and heat resistance of the copolymer.

[0020] By adding hydroxypropyl acrylate, the reactive cross-linking network is formed, promoting the full reaction of the epoxy groups. The steric hindrance effect of the branched structure of the branched alkyl acrylate can reduce the melt viscosity, which is conducive to lowering the glass transition temperature and enabling the resin to melt quickly at low temperatures. The ether bond in the tetrahydrofuran ring of the tetrahydrofuran ring-containing acrylate monomer helps to improve the chain segment flexibility, synergistically working with the branched acrylate to reduce the melt viscosity. Moreover, the oxygen atoms in the tetrahydrofuran ring can participate in the ring-opening reaction of the epoxy group under the reaction conditions, forming a stable THF-epoxy ether bond cross-linking network, which helps to enhance the chain segment flexibility and optimize the low-temperature flow properties.

[0021] Glycidyl methacrylate directly introduces epoxy groups and reacts with hydroxyl groups to form a stable cross-linked network. Allyl glycidyl ether enhances the cross-linking density through side chain reactive groups, and its allyl flexible chain segments help to alleviate rigidity. The two can synergistically further improve the bonding strength and anti-deviability.

[0022] Preferably, the hydroxyl-containing styrene derivative is selected from at least one of p-(2-hydroxyethoxy)styrene, p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl-4-hydroxystyrene, and 4-hydroxy-3-methoxystyrene.

[0023] Preferably, the tetrahydrofuran ring-containing acrylate monomer is selected from at least one of tetrahydrofurfuryloxyethyl acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, and ditetrahydrofurfuryl acrylate.

[0024] Preferably, the branched alkyl acrylate is selected from at least one of 2-isooctyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate and isobornyl acrylate.

[0025] Preferably, the hydroxyl-containing styrene derivative is p-hydroxystyrene; and / or

[0026] The tetrahydrofuran ring-containing acrylate monomer is tetrahydrofurfuryloxyethyl acrylate; and / or

[0027] The branched alkyl acrylate is 2-ethylhexyl acrylate.

[0028] By adopting the above technical solution, hydroxystyrene has high reactivity and good compatibility with styrene and acrylates; the ether bond (COC) of the THF ring in tetrahydrofurfuryloxyethyl acrylate and the ethoxy chain segment can both improve the flexibility of the chain segment and synergistically reduce the melt viscosity with branched acrylates. In addition, its ethoxy chain segment has similar polarity to styrene and hydroxypropyl acrylate, and has better compatibility, which helps to avoid phase separation; 2-ethylhexyl acrylate has better low-temperature fluidity, which helps to improve migration resistance.

[0029] Preferably, the copolymer has a molecular weight of 30,000-40,000, a molecular weight distribution of 1.8-3.0, a glass transition temperature of 55-70° C., a softening point of 100-115° C., and an epoxy group content of 4.5-7.5 wt %.

[0030] By adopting the above technical solution, the copolymer can take into account both low-temperature fixing properties and storage stability, while ensuring the melt fluidity of the copolymer, making it suitable for a variety of printers; by controlling the epoxy group content, the copolymer can have better bonding strength and excellent processability, avoiding the difficulty in crushing caused by excessive epoxy group content and excessive cross-linking of the resin; by controlling the molecular weight of the copolymer, its crushing performance is further improved while ensuring that the copolymer has better mechanical strength, and by controlling the molecular weight distribution, the melt uniformity is further improved and the low-temperature fixing properties are improved.

[0031] The second aspect of the present application provides a method for preparing a styrene-acrylate-epoxy graft copolymer for toner, comprising the following steps:

[0032] Under nitrogen protection, styrene monomers, acrylate monomers and epoxy group-containing monomers are dissolved in an organic solvent, a free radical polymerization initiator is added, and the mixture is stirred at 75-95°C and a speed of 200-300 r / min for 2-4 hours. A chain transfer agent is added, and the mixture is stirred at 70-80°C and a speed of 300-400 r / min for 1-3 hours. The solvent is removed by distillation under reduced pressure to obtain a primary product.

[0033] The obtained copolymer is mixed with an epoxy ring-opening catalyst, and reacted at 90-95° C. for 4-5 hours; and then cooled, precipitated, filtered, and dried to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0034] By adopting the above technical solution, under nitrogen protection, styrene, acrylate, and epoxy monomers are copolymerized by free radicals to form a prepolymer containing epoxy groups in the main chain; the prepolymer is synthesized by a one-step method, which simplifies the production process and shortens the reaction time; the molecular weight is regulated by adding a chain transfer agent to avoid excessive cross-linking; and by adding an epoxy ring-opening catalyst, the partial ring opening of the epoxy groups is further induced to form a controllable branched or cross-linked network, thereby enhancing the heat resistance and anti-drift properties of the resin.

[0035] Preferably, the free radical polymerization initiator is selected from at least one of benzoyl peroxide, azobisisobutyronitrile, and potassium persulfate, and the amount used is 0.5-2% of the total weight of the monomers.

[0036] Preferably, the chain transfer agent is dodecyl mercaptan, and the amount used is 0.1-0.5% of the total weight of the monomers.

[0037] Preferably, the epoxy ring-opening catalyst is triphenylphosphine or an amine compound, and the amount used is 2-5% of the molar amount of the epoxy group.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. This application adopts a styrene-acrylate-epoxy graft copolymer structure. The styrene rigid chain segment, the acrylate flexible chain segment and the reactive epoxy group cooperate with each other and work synergistically to significantly improve the low-temperature fixability, enhance the anti-offset property, and have excellent charge stability.

[0040] 2. This application optimizes the comonomers and their ratios to make the copolymer have more balanced storage stability and fixing efficiency, and improve the melting uniformity, which helps to improve the developing performance.

[0041] 3. The preparation method of the present application simplifies the production process, improves production efficiency, and helps to improve product consistency by combining free radical polymerization with post-curing process. DETAILED DESCRIPTION

[0042] To further help understand the technical solution of the present invention, the following provides several specific implementation examples to describe the technical solution of the present invention in more detail. All of these described embodiments are only some embodiments of the present invention, not all.

[0043] In this application, % (w / w) and wt% both refer to weight percentage, % (v / v) refers to volume percentage, and the solid-to-liquid ratio (w / v) refers to the mass-to-volume ratio in kg / L or g / ml.

[0044] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0045] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the optional numerical distribution within the numerical interval is considered continuous and includes the two numerical endpoints of the numerical range (i.e., the minimum and maximum values), as well as every numerical value between these two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two numerical endpoints of the numerical range, as well as every integer between the two numerical endpoints, and is equivalent to directly listing each integer in this document. In addition, when multiple ranges are provided to describe a feature or characteristic, these ranges may be combined. In other words, unless otherwise specified, ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0046] The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments; and the reaction devices, monomers, compounds, etc. involved in the following embodiments are all commercially available.

[0047] The following examples are provided to further illustrate the present invention, but the present invention is not limited thereto.

[0048] Example

[0049] Example 1

[0050] This embodiment discloses a styrene-acrylate-epoxy graft copolymer for toner, and its preparation method is as follows:

[0051] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes to exhaust the air;

[0052] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0053] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0054] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0055] Example 2

[0056] The only difference between this embodiment and embodiment 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0057] Under nitrogen protection, 2000 g of toluene, 350 g of styrene, 150 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 320 g of 2-ethylhexyl acrylate, 40 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0058] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0059] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0060] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0061] Example 3

[0062] The only difference between this embodiment and embodiment 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0063] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-isooctyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes to exhaust the air;

[0064] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0065] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0066] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0067] Example 4

[0068] The only difference between this embodiment and embodiment 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0069] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of 3-methyl-4-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0070] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0071] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0072] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0073] Example 5

[0074] The only difference between this embodiment and embodiment 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0075] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0076] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0077] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0078] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0079] Comparative Example

[0080] Comparative Example 1

[0081] This comparative example discloses a binder resin copolymer for toner, and the preparation method is as follows:

[0082] Under nitrogen protection, 2000 g of toluene, 500 g of styrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes to exhaust the air;

[0083] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0084] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0085] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0086] Comparative Example 2

[0087] The only difference between this comparative example and Example 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0088] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 120 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0089] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0090] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0091] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0092] Comparative Example 3

[0093] The only difference between this comparative example and Example 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0094] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, and 100 g of glycidyl methacrylate were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes to exhaust the air.

[0095] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0096] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0097] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0098] Comparative Example 4

[0099] This comparative example discloses a styrene-acrylate-epoxy graft copolymer for toner, and its preparation method is as follows:

[0100] Under nitrogen protection, 2000 g of toluene, 480 g of styrene, 120 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, and 80 g of tetrahydrofurfuryloxyethyl acrylate were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes to exhaust the air.

[0101] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0102] The initial product was added to a 5-fold volume of methanol solution, stirred at 600 rpm for 10 minutes, allowed to stand for 4 hours, filtered, washed with methanol 3 times, and vacuum dried at 50° C. for 24 hours to obtain a binder resin copolymer for toner.

[0103] Comparative Example 5

[0104] The only difference between this comparative example and Example 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0105] Under nitrogen protection, 2000 g of toluene, 250 g of styrene, 250 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0106] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0107] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0108] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0109] Comparative Example 6

[0110] The only difference between this comparative example and Example 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0111] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 160 g of 2-ethylhexyl acrylate, 200 g of tetrahydrofurfuryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0112] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0113] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 7.5 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0114] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0115] Comparative Example 7

[0116] The only difference between this comparative example and Example 1 is that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows:

[0117] Under nitrogen protection, 2000 g of toluene, 400 g of styrene, 100 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate, 50 g of glycidyl methacrylate, and 50 g of allyl glycidyl ether were added to the reaction flask, and nitrogen was introduced at a flow rate of 10 mL / min for 30 minutes, and the air was exhausted;

[0118] 10 g of benzoyl peroxide was dissolved in toluene to prepare a 5 wt% initiator solution; the initiator solution was slowly added dropwise to the reaction flask, the reaction temperature was controlled at 90°C, and the reaction was stirred at 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80°C and 300 rpm for 3 hours. The product was then distilled under reduced pressure at 70°C to obtain a transparent viscous primary product.

[0119] The primary product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt %, 8.3 g of triphenylphosphine was added thereto, and the mixture was reacted at 100°C and 200 rpm under nitrogen protection for 4 hours;

[0120] After the reaction liquid is cooled, it is slowly added dropwise to a 5-fold volume of methanol solution while stirring, and stirring is continued at 600 rpm for 10 minutes. After standing for 4 hours, it is filtered and washed with methanol 3 times to remove unreacted monomers and catalyst residues; and then vacuum dried at 50°C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0121] Performance testing

[0122] The resin copolymer samples in each example and comparative example were taken, and the softening point (Tm) and glass transition temperature (Tg) were measured by differential scanning calorimetry (DSC), the molecular weight and molecular weight distribution were measured by gel permeation chromatography (GPC), and the epoxy group content was measured by infrared spectroscopy (FTIR). The results are summarized in Table 1.

[0123] Application performance testing: Samples of the binder resin copolymers used in each example and comparative example were mixed with carbon black and a charge control agent according to conventional methods in the art to form toner. Using a fusing tester, the toner was applied to standard paper. The fusing roller temperature was gradually lowered until image fastness reached ≥95%. The lowest fusing temperature was then measured. 1000 pages were printed continuously at a fusing roller temperature of 140°C. The percentage of pages in which toner adhered to the fusing roller was calculated to determine the incidence of thermal offset. The toner was then placed in a high-temperature, high-humidity environment (40°C, 80% RH) for 24 hours to observe any clumping or adhesion to the container walls. The results are summarized in Table 2.

[0124] Table 1

[0125]

[0126] Table 2

[0127]

[0128] As can be seen from Examples 1-5 and Comparative Examples 1-7, in conjunction with Tables 1 and 2, the styrene-acrylate-epoxy graft copolymer, according to the method disclosed herein, has a softening point of 104-113°C, a glass transition temperature of 58-67°C, a molecular weight of 30,000-37,500, a molecular weight distribution of 1.9-2.5, and an epoxy group content of 4.8-7.0%. Using the styrene-acrylate-epoxy graft copolymer as a binder resin for toners can impart excellent application properties to the toners, including a low fixing temperature, a low incidence of thermal offset, excellent storage stability, and resistance to roller sticking.

[0129] In combination with Examples 1-5 and Comparative Examples 1-7, it can be seen that by optimizing the selection and ratio of comonomers and adding hydroxyl-containing styrene, the cross-linking network is enriched, and p-hydroxystyrene helps to ensure cross-linking efficiency. However, when the proportion of p-hydroxystyrene is too high, uneven cross-linking density, excessive molecular weight and poor fluidity are easily caused. By adding branched acrylates and acrylate monomers containing tetrahydrofuran rings, the toner has excellent low-temperature fixing stability and thermal offset stability. Among them, 2-ethylhexyl acrylate has better compatibility with the copolymer system, and tetrahydrofurfuryloxyethyl acrylate can give the toner better flexibility and adhesion. However, when the content of tetrahydrofurfuryloxyethyl acrylate is too high, phase separation is easily caused, and the stability of the toner is reduced. By combining glycidyl methacrylate with allyl glycidyl ether, the copolymer resin has appropriate cross-linking density and cross-linking efficiency. When the amount of glycidyl methacrylate is excessive, excessive cross-linking is easily caused, the brittleness of the copolymer resin is increased, and the thermal offset stability is reduced. When the proportion of allyl glycidyl ether is too high, insufficient cross-linking efficiency may result.

[0130] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A styrene-acrylate-epoxy graft copolymer for toner, characterized in that: It is copolymerized by the following components: 40-60wt% styrene monomer, 30-50wt% of acrylic acid ester monomer, 5-15 wt% of an epoxy group-containing monomer; The copolymer has a molecular weight of 20,000-50,000, a glass transition temperature of 50-70°C, a softening point of 90-120°C, and an epoxy group content of 3-10%; The styrene monomers are styrene and a hydroxyl-containing styrene derivative in a mass ratio of (9-7):(3-1); The acrylic acid ester monomers are hydroxypropyl acrylate, branched alkyl acrylate and tetrahydrofuran ring-containing acrylic acid ester monomers in a mass ratio of 1:(6-8):(1-3); The epoxy group-containing monomers are glycidyl methacrylate and allyl glycidyl ether in a mass ratio of (9-8):(2-1); The hydroxyl-containing styrene derivative is selected from at least one of p-(2-hydroxyethoxy)styrene, p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl-4-hydroxystyrene, and 4-hydroxy-3-methoxystyrene; The branched alkyl acrylate is selected from at least one of 2-isooctyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, and isobornyl acrylate; The tetrahydrofuran ring-containing acrylate monomer is selected from at least one of tetrahydrofurfuryloxyethyl acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, and ditetrahydrofurfuryl acrylate.

2. The styrene-acrylate-epoxy graft copolymer for toner according to any one of claim 1, characterized in that: The hydroxyl-containing styrene derivative is p-hydroxystyrene; and / or The tetrahydrofuran ring-containing acrylate monomer is tetrahydrofurfuryloxyethyl acrylate; and / or The branched alkyl acrylate is 2-ethylhexyl acrylate.

3. The styrene-acrylate-epoxy graft copolymer for toner according to claim 2, characterized in that: The copolymer has a molecular weight of 30,000-40,000, a molecular weight distribution of 1.8-3.0, a glass transition temperature of 55-70° C., a softening point of 100-115° C., and an epoxy group content of 4.5-7.5 wt %.

4. A method for preparing the styrene-acrylate-epoxy graft copolymer for toner according to any one of claims 1 to 3, characterized in that: The following steps are involved: Under nitrogen protection, styrene monomers, acrylate monomers and epoxy group-containing monomers are dissolved in an organic solvent, a free radical polymerization initiator is added, and the mixture is stirred at 75-95°C and a speed of 200-300 r / min for 2-4 hours. A chain transfer agent is added, and the mixture is stirred at 70-80°C and a speed of 300-400 r / min for 1-3 hours. The solvent is removed by distillation under reduced pressure to obtain a primary product. The obtained copolymer is mixed with an epoxy ring-opening catalyst, and reacted at 90-95° C. for 4-5 hours; and then cooled, precipitated, filtered, and dried to obtain a styrene-acrylate-epoxy graft copolymer for toner.

5. The method for preparing the styrene-acrylate-epoxy graft copolymer for toner according to claim 4, characterized in that: The free radical polymerization initiator is selected from at least one of benzoyl peroxide, azobisisobutyronitrile, and potassium persulfate, and the amount used is 0.5-2% of the total weight of the monomers.

6. The method for preparing the styrene-acrylate-epoxy graft copolymer for toner according to claim 4, characterized in that: The chain transfer agent is dodecyl mercaptan, and the amount used is 0.1-0.5% of the total weight of the monomers.

7. The method for preparing a styrene-acrylate-epoxy graft copolymer for toner according to claim 4, characterized in that: The epoxy ring-opening catalyst is triphenylphosphine or an amine compound, and the amount used is 2-5% of the molar amount of the epoxy group.

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