Styrene-acrylate-epoxy graft copolymer for powdered ink and preparation method of styrene-acrylate-epoxy graft copolymer

Abstract

The invention relates to the field of adhesive resin for powdered ink, and particularly discloses a styrene-acrylate-epoxy graft copolymer for powdered ink and a preparation method thereof. The styrene-acrylate-epoxy graft copolymer for the powdered ink is prepared by copolymerizing the following components: 40 to 60 weight percent of styrene monomer, 30 to 50 weight percent of acrylate monomer and 5 to 15 weight percent of epoxy group-containing monomer, the molecular weight of the copolymer is 20000-50000, the glass transition temperature is 50-70 DEG C, the softening point is 90-120 DEG C, and the content of epoxy groups is 3-10%. The copolymer disclosed by the invention has the advantages of excellent low-temperature fixing property and low thermal migration property.

Description

Technical Field

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

[0002] Toner (also known as carbon powder) is a powdery substance used for imaging and fixing on paper in laser printers and copiers, mainly including components such as binder resin, colorant (such as carbon black), charge control agent, and external additives. Among them, the binder resin usually accounts for 80%-90% of the total toner amount, and its performance directly determines key indicators such as the fixing characteristics, charging performance, fluidity, and storage stability of the toner. The binder resin for toner generally needs to meet the following basic requirements: it can quickly melt and adhere to the paper during heat fixing; it can quickly cure after being separated from high temperature to ensure image clarity; it has appropriate viscoelasticity and anti-offset properties to prevent image blurring; it has good comminution performance. With the development of office automation equipment towards high speed, miniaturization, and energy conservation, the market has put forward more stringent requirements for the low-temperature fixing performance of toner binder resin, that is, the resin needs to melt at a lower temperature and can quickly cure.

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

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

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

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

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows: In the first aspect of this application, there is provided a styrene-acrylate-epoxy graft copolymer for toner, which is copolymerized from the following components: 40-60wt% of styrene monomers, 30-50wt% of acrylate monomers, 5-15wt% of epoxy group-containing monomers; The molecular weight of the copolymer is 20,000 - 50,000, the glass transition temperature is 50 - 70 °C, the softening point is 90 - 120 °C, and the epoxy group content is 3 - 10%.

[0008] 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, enabling the resin copolymer to have excellent low-temperature fixing performance, good pulverization characteristics, and stable charging performance; styrene monomers can provide a rigid skeleton for the copolymer, maintaining the mechanical strength and glass transition temperature of the resin and preventing toner from caking during storage; acrylate monomers reduce the melt viscosity through long-chain alkyl groups, significantly improving the low-temperature fixing performance, and epoxy group monomers enhance the bonding strength and heat resistance through ring-opening cross-linking, reducing the thermal offset phenomenon during the fixing process, realizing the synergistic effect of styrene rigid chain segments, acrylate flexible chain segments, and epoxy reactive groups, and making the copolymer have excellent low-temperature fixing performance, good pulverization characteristics, and stable charging performance; By restricting the mass fraction of styrene monomers, the copolymer has better mechanical properties, low-temperature fixing property, and anti-offset property. The mass fraction of styrene monomers is controlled within 40 - 60%, making the copolymer have better rigidity, being easier to pulverize, improving the processing performance, and at the same time avoiding the possibility of poor low-temperature fixing performance caused by too high melting temperature; the mass fraction of acrylate monomers is controlled within 30 - 50%, making the copolymer have better flexibility, contributing to improving the fixing efficiency, and making the copolymer have an appropriate viscosity, endowing it with better anti-offset property; by controlling the mass fraction of epoxy reaction groups, the copolymer has an appropriate cross-linking density, avoiding the possibility of a decrease in bonding strength caused by insufficient cross-linking density, and avoiding the possibility of excessive cross-linking of the bonding resin, deterioration of pulverization performance, and poor processing performance caused by too high a proportion of reaction groups.

[0009] Preferably, the styrene monomers are styrene and styrene derivatives containing hydroxyl groups with a mass ratio of (9 - 7):(3 - 1).

[0010] Preferably, the acrylate monomers are hydroxypropyl acrylate, branched-chain alkyl acrylate, and acrylate monomers containing a tetrahydrofuran ring with a mass ratio of 1:(6 - 8):(1 - 3).

[0011] Preferably, the epoxy group-containing monomers are glycidyl methacrylate and allyl glycidyl ether with a mass ratio of (9 - 8):(2 - 1).

[0012] By adopting the above technical solution, through the optimization of each monomer and the resin formula in this application, the improvement of low-temperature fixing, high adhesion, heat resistance, and wear resistance is achieved.

[0013] By copolymerizing a hydroxyl-containing styrene derivative with styrene, while ensuring the solid-state stability of the resin, hydroxyl reaction sites are introduced, enabling the rigid styrene backbone to form a reactive crosslinking network with epoxy groups and hydroxypropyl acrylate, which is beneficial to improving the stability and heat resistance of the copolymer; By adding hydroxypropyl acrylate to participate in the formation of the reactive crosslinking network and promote the full reaction of epoxy groups; the steric hindrance effect of the branched-chain structure of the branched-chain alkyl acrylate can reduce the melt viscosity, which is beneficial to lowering the glass transition temperature and enabling the resin to melt rapidly at low temperatures; the ether bond in the tetrahydrofuran ring of the acrylate monomer containing a tetrahydrofuran ring helps to improve the chain segment flexibility and, in synergy with the branched-chain acrylate, reduces the melt viscosity; moreover, the oxygen atom in the tetrahydrofuran ring can participate in the ring-opening reaction of epoxy groups under reaction conditions and can form a stable THF-epoxy ether bond crosslinking network, which helps to enhance the chain segment flexibility and optimize the low-temperature flow performance; Glycidyl methacrylate directly introduces epoxy groups and forms a stable crosslinking network with hydroxyl groups. Allyl glycidyl ether enhances the crosslinking density through side-chain reactive groups, and its allyl flexible chain segment helps to relieve rigidity. The two working together can further improve the bonding strength and anti-offset property.

[0014] 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.

[0015] Preferably, the acrylate monomer containing a tetrahydrofuran ring is selected from at least one of tetrahydrofurfuryl oxyethyl acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, and bis(tetrahydrofurfuryl) acrylate.

[0016] Preferably, the branched-chain alkyl acrylate is selected from at least one of 2-isooctyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, and isobornyl acrylate.

[0017] Preferably, the hydroxyl-containing styrene derivative is p-hydroxystyrene; and / or the acrylate monomer containing a tetrahydrofuran ring is tetrahydrofurfuryl oxyethyl acrylate; and / or the branched-chain alkyl acrylate is 2-ethylhexyl acrylate.

[0018] By adopting the above technical solution, p-hydroxystyrene has high reactivity and good compatibility with styrene and acrylate; the ether bond (C-O-C) of the THF ring and the ethoxy chain segment in tetrahydrofurfuryl oxyethyl acrylate can both improve the chain segment flexibility, and can synergistically reduce the melt viscosity with branched acrylate. Moreover, its ethoxy chain segment has the same polarity as styrene and hydroxypropyl acrylate, with better compatibility, which helps to avoid phase separation; 2-ethylhexyl acrylate has better low-temperature fluidity, which helps to improve the migration resistance.

[0019] 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%.

[0020] By adopting the above technical solution, the copolymer can balance the low-temperature fixing property and storage stability, while ensuring the melt fluidity of the copolymer, making it applicable to various printers; by controlling the epoxy group content, the copolymer can have better bonding strength and excellent processability, avoiding the difficulty in pulverization caused by excessive cross-linking due to too high epoxy group content; by controlling the molecular weight of the copolymer, its pulverization performance is further improved on the condition of ensuring better mechanical strength of the copolymer, and by controlling the molecular weight distribution, the melt uniformity is further improved and the low-temperature fixing property is improved.

[0021] In the second aspect of the present application, a preparation method of a styrene-acrylate-epoxy graft copolymer for toner is provided, including the following steps: Under nitrogen protection, styrene monomers, acrylate monomers and monomers containing epoxy groups are dissolved in an organic solvent, a radical polymerization initiator is added, and after stirring and reacting at 75 - 95 °C at a rotation speed of 200 - 300 r / min for 2 - 4 hours, a chain transfer agent is added, and the reaction continues at 70 - 80 °C at a rotation speed of 300 - 400 r / min for 1 - 3 hours; the solvent is removed by vacuum distillation to obtain a crude product; The obtained copolymer is mixed with an epoxy ring-opening catalyst and reacted at 90 - 95 °C for 4 - 5 hours; then, after cooling, precipitation, filtration and drying, a styrene-acrylate-epoxy graft copolymer for toner is obtained.

[0022] By adopting the above technical solution, under nitrogen protection, styrene, acrylate and epoxy monomers form a prepolymer with epoxy groups in the main chain through free radical copolymerization; by synthesizing the prepolymer by a one-step method, the production process is simplified and the reaction time is shortened; by adding a chain transfer agent to regulate the molecular weight, excessive cross-linking is avoided; and by adding an epoxy ring-opening catalyst, further partial ring-opening of the epoxy group is initiated to form a controllable branched or cross-linked network, enhancing the heat resistance and anti-offset property of the resin.

[0023] Preferably, the free radical polymerization initiator is selected from at least one of benzoyl peroxide, azobisisobutyronitrile, and potassium persulfate, and the dosage is 0.5-2% of the total mass of the monomers.

[0024] Preferably, the chain transfer agent is dodecyl mercaptan, and the dosage is 0.1-0.5% of the total mass of the monomers.

[0025] Preferably, the epoxy ring-opening catalyst is triphenylphosphine or an amine compound, and the dosage is 2-5% of the molar amount of the epoxy group.

[0026] In summary, the present application has the following beneficial effects: 1. The present application adopts a styrene-acrylate-epoxy graft copolymer structure. The rigid styrene chain segment, the flexible acrylate chain segment, and the reactive epoxy group cooperate with each other and act synergistically, significantly improving the low-temperature fixing property, enhancing the anti-offset property, and having excellent charge stability performance.

[0027] 2. By optimizing the copolymer monomers and their ratios, the copolymer of the present application has more balanced storage stability and fixing efficiency, and improves the melting uniformity, which helps to improve the developing performance.

[0028] 3. The preparation method of the present application combines free radical polymerization and post-curing process, simplifies the production process, improves the production efficiency, and helps to improve the product consistency. Specific Embodiments

[0029] To further help understand the technical solution of the present invention, several specific implementation examples are provided below to more specifically describe the technical solution of the present invention. All the described embodiments are only partial embodiments of the present invention, not all; In the present application, %(w / w) and wt% both represent weight percentage, %(v / v) refers to volume percentage, and the solid-liquid ratio (w / v) refers to the mass-volume ratio kg / L or g / ml.

[0030] The temperature parameters in the present application, unless otherwise specifically defined, allow both constant temperature treatment and variation within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0031] In this application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the selectable numerical values are considered continuous within the above numerical intervals, and include the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints. In this article, it is equivalent to directly listing each integer. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed in this article should be understood to include any and all sub-ranges subsumed therein.

[0032] The following specific embodiments can 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.

[0033] The following embodiments are further illustrations of the present invention, and the present invention is not limited thereto.

[0034] Embodiment Embodiment 1

[0035] This embodiment discloses a styrene-acrylate-epoxy graft copolymer for toner, and its preparation method is as follows: Under nitrogen protection, add 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 oxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether to the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to discharge air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly drop the initiator solution into the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at a speed of 300 rpm at 80 °C for 3 hours, and carry out vacuum distillation under the condition of 70 °C to obtain a transparent viscous primary product; Dissolve the primary product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react at 100 °C and 200 rpm under nitrogen protection for 4 hours; After the reaction solution is cooled, the reaction solution is slowly added dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, and stirring is continued at a speed of 600 rpm for 10 minutes. After standing for 4 hours, filtration is carried out, and then washing with methanol is carried out 3 times to remove unreacted monomers and catalyst residues; then vacuum drying is carried out at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0036] Example 2

[0037] The difference between this example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 to the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to discharge air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly add the initiator solution to the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at a speed of 300 rpm at 80 °C for 3 hours, and carry out vacuum distillation under reduced pressure at 70 °C to obtain a transparent viscous crude product; Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react at 100 °C and 200 rpm under nitrogen protection for 4 hours; After the reaction solution is cooled, the reaction solution is slowly added dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, and stirring is continued at a speed of 600 rpm for 10 minutes. After standing for 4 hours, filtration is carried out, and then washing with methanol is carried out 3 times to remove unreacted monomers and catalyst residues; then vacuum drying is carried out at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0038] Example 3

[0039] The difference between this example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 to the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to discharge air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly add the initiator solution dropwise to the reaction flask, control the reaction temperature at 90 °C, stir the reaction at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue the reaction at 80 °C and a speed of 300 rpm for 3 hours. Carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product; Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react under nitrogen protection at 100 °C and 200 rpm for 4 hours; After the reaction solution is cooled, slowly add the reaction solution dropwise to a methanol solution with 5 times the volume while stirring, continue to stir at a speed of 600 rpm for 10 minutes, let it stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues; then carry out vacuum drying at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0040] Example 4

[0041] The difference between this example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 tetrahydrofurfuryl oxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether to the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to discharge air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly add the initiator solution dropwise to the reaction flask, control the reaction temperature at 90 °C, stir the reaction at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue the reaction at 80 °C and a speed of 300 rpm for 3 hours. Carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product; Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react under nitrogen protection at 100 °C and 200 rpm for 4 hours; After the reaction solution is cooled, slowly add the reaction solution dropwise to a methanol solution with 5 times the volume while stirring, continue to stir at a speed of 600 rpm for 10 minutes, let it stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues; then carry out vacuum drying at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0042] Example 5

[0043] The difference between this example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer used for toner is as follows: Under nitrogen protection, add 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 into the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to discharge air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly drop the initiator solution into the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C at a speed of 300 rpm for 3 hours, and perform vacuum distillation at 70 °C to obtain a transparent viscous primary product; Dissolve the primary product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react at 100 °C and 200 rpm under nitrogen protection for 4 hours; After the reaction solution is cooled, slowly drop the reaction solution into a methanol solution with 5 times the volume while stirring, continue to stir at a speed of 600 rpm for 10 minutes, let it stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues; then dry in vacuum at 50 °C for 24 hours to obtain the styrene-acrylate-epoxy graft copolymer used for toner.

[0044] Comparative Example

[0045] Comparative Example 1 This comparative example discloses a binder resin copolymer for toner, and the preparation method is as follows: Under nitrogen protection, add 2000 g of toluene, 500 g of styrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryl acryloxyethyl acrylate, 90 g of glycidyl methacrylate, and 10 g of allyl glycidyl ether into the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to discharge air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly drop the initiator solution into the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C at a speed of 300 rpm for 3 hours, and perform vacuum distillation at 70 °C to obtain a transparent viscous primary product; Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react at 100 °C and 200 rpm for 4 hours under nitrogen protection; After the reaction solution is cooled, slowly add the reaction solution dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, continue to stir at a speed of 600 rpm for 10 minutes, stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues; then dry under vacuum at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 to the reaction flask, and pass nitrogen at a flow rate of 10 mL / min for 30 minutes to expel air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly add the initiator solution to the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C and 300 rpm for 3 hours, and carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product; Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react at 100 °C and 200 rpm for 4 hours under nitrogen protection; After the reaction solution is cooled, slowly add the reaction solution dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, continue to stir at a speed of 600 rpm for 10 minutes, stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues; then dry under vacuum at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0047] Comparative Example 3 The difference between this comparative example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 into the reaction flask. Pass nitrogen at a flow rate of 10 mL / min for 30 minutes to expel air. Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution. Slowly add the initiator solution to the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C and 300 rpm for 3 hours. Carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product. Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%. Add 7.5 g of triphenylphosphine thereto, and react under nitrogen protection at 100 °C and 200 rpm for 4 hours. After the reaction solution is cooled, slowly add the reaction solution dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, continue to stir at a speed of 600 rpm for 10 minutes, let it stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues. Then carry out vacuum drying at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0048] Comparative Example 4 This comparative example discloses a styrene-acrylate-epoxy graft copolymer for toner, and its preparation method is as follows: Under nitrogen protection, add 2000 g of toluene, 480 g of styrene, 120 g of p-hydroxystyrene, 40 g of hydroxypropyl acrylate, 280 g of 2-ethylhexyl acrylate, 80 g of tetrahydrofurfuryloxyethyl acrylate into the reaction flask. Pass nitrogen at a flow rate of 10 mL / min for 30 minutes to expel air. Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution. Slowly add the initiator solution to the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C and 300 rpm for 3 hours. Carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product. Add the crude product to a methanol solution with a volume 5 times that of the crude product, continue to stir at a speed of 600 rpm for 10 minutes, let it stand for 4 hours and then filter, and wash with methanol 3 times, and then carry out vacuum drying at 50 °C for 24 hours to obtain a binder resin copolymer for toner.

[0049] Comparative Example 5 The difference between this comparative example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 to the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to expel air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly add the initiator solution to the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C and 300 rpm for 3 hours, and carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product; Dissolve the crude product in N-methylpyrrolidone to adjust the solid content to 25 wt%, add 7.5 g of triphenylphosphine thereto, and react at 100 °C and 200 rpm under nitrogen protection for 4 hours; After the reaction solution is cooled, slowly add the reaction solution dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, continue to stir at a speed of 600 rpm for 10 minutes, let it stand for 4 hours and then filter, and wash with methanol 3 times to remove unreacted monomers and catalyst residues; then dry in vacuum at 50 °C for 24 hours to obtain the styrene-acrylate-epoxy graft copolymer for toner.

[0050] Comparative Example 6 The difference between this comparative example and Example 1 is only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner is as follows: Under nitrogen protection, add 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 to the reaction flask, and introduce nitrogen at a flow rate of 10 mL / min for 30 minutes to expel air; Dissolve 10 g of benzoyl peroxide in toluene to prepare a 5 wt% initiator solution; slowly add the initiator solution to the reaction flask, control the reaction temperature at 90 °C, stir and react at a speed of 300 rpm for 3 hours, then add 3 g of dodecyl mercaptan, and continue to react at 80 °C and 300 rpm for 3 hours, and carry out vacuum distillation at 70 °C to obtain a transparent viscous crude product; The crude product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt%, 7.5 g of triphenylphosphine was added thereto, and the reaction was carried out at 100 °C and 200 rpm for 4 hours under nitrogen protection; After the reaction solution was cooled, the reaction solution was slowly added dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, and stirring was continued at a speed of 600 rpm for 10 minutes. After standing for 4 hours, filtration was carried out, and then washing with methanol was carried out 3 times to remove unreacted monomers and catalyst residues; then vacuum drying was carried out at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0051] Comparative Example 7 The difference between this comparative example and Example 1 was only that the preparation method of the styrene-acrylate-epoxy graft copolymer for toner was as follows: 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 to discharge air; 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 carried out with stirring at a speed of 300 rpm for 3 hours. Then, 3 g of dodecyl mercaptan was added, and the reaction was continued at 80 °C with stirring at a speed of 300 rpm for 3 hours. Under reduced pressure distillation was carried out at 70 °C to obtain a transparent viscous crude product; The crude product was dissolved in N-methylpyrrolidone to adjust the solid content to 25 wt%, 8.3 g of triphenylphosphine was added thereto, and the reaction was carried out at 100 °C and 200 rpm for 4 hours under nitrogen protection; After the reaction solution was cooled, the reaction solution was slowly added dropwise to a methanol solution with a volume 5 times that of the reaction solution while stirring, and stirring was continued at a speed of 600 rpm for 10 minutes. After standing for 4 hours, filtration was carried out, and then washing with methanol was carried out 3 times to remove unreacted monomers and catalyst residues; then vacuum drying was carried out at 50 °C for 24 hours to obtain a styrene-acrylate-epoxy graft copolymer for toner.

[0052] Performance detection test

[0053] Samples of the resin copolymers 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 detected by gel permeation chromatography (GPC), and the epoxy group content was detected by infrared spectroscopy (FTIR); the results were summarized in Table 1.

[0054] Application performance detection: Take the toner binder resin copolymer samples in each example and comparative example, mix them with carbon black and charge control agent according to the conventional methods in the art to prepare toner, use a fusing tester, coat the toner on standard paper, gradually reduce the fusing roller temperature until the image fastness ≥ 95%, and detect the lowest fusing temperature; Continuously print 1000 pages at a fusing roller temperature of 140 °C, count the proportion of the number of pages where the toner adheres to the fusing roller, and detect the thermal offset incidence rate; Place the toner in a high-temperature and high-humidity environment (40 °C, 80% RH) for 24 hours, and observe whether it cakes or adheres to the container wall. The results are summarized in Table 2.

[0055] Table 1

[0056] Table 2

[0057] Combining Examples 1-5 and Comparative Examples 1-7 and combining Tables 1 and 2, it can be seen that, referring to the method disclosed in the present application, the softening point of the styrene-acrylate-epoxy graft copolymer is 104-113 °C, the glass transition temperature is 58-67 °C, the molecular weight is 30,000-37,500, the molecular weight distribution is 1.9-2.5, and the epoxy group content is 4.8-7.0%. Applying the styrene-acrylate-epoxy graft copolymer as a toner binder resin can endow the toner with excellent application properties such as low fusing temperature, low thermal offset incidence rate, excellent storage stability, and anti-sticking roller performance.

[0058] Combining Examples 1-5 and Comparative Examples 1-7, it can be seen that by optimizing the selection and ratio of copolymerization monomers, by adding hydroxy styrene, the cross-linked network becomes richer. At the same time, p-hydroxy styrene helps to ensure the cross-linking efficiency. However, when the proportion of p-hydroxy styrene is too high, it is easy to cause uneven cross-linking density and too large molecular weight, resulting in poor fluidity; By adding branched-chain acrylate and acrylate monomers containing tetrahydrofuran rings, the toner has excellent low-temperature fusing stability and thermal offset stability. Among them, 2-ethylhexyl acrylate has better compatibility with the copolymerization system, and tetrahydrofurfuryl oxyethyl acrylate can endow the toner with better flexibility and adhesion. However, when the content of tetrahydrofurfuryl oxyethyl acrylate is too high, it is easy to cause phase separation and reduce the stability of the toner; By combining glycidyl methacrylate and allyl glycidyl ether, the copolymer resin has appropriate cross-linking density and cross-linking efficiency. When glycidyl methacrylate is in excess, it is easy to cause over-cross-linking, increasing the brittleness of the copolymer resin and decreasing the thermal offset stability; When the proportion of allyl glycidyl ether is too high, it may lead to insufficient cross-linking efficiency.

[0059] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively 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 from the following components: 40 - 60 wt% of styrene monomers, 30 - 50 wt% of acrylate monomers, 5 - 15 wt% of monomers containing epoxy groups; 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 styrene derivatives containing hydroxyl groups with a mass ratio of (9 - 7):(3 - 1); The acrylate monomers are hydroxypropyl acrylate, branched alkyl acrylate, and acrylate monomers containing a tetrahydrofuran ring with a mass ratio of 1:(6 - 8):(1 - 3); The monomers containing epoxy groups are glycidyl methacrylate and allyl glycidyl ether with a mass ratio of (9 - 8):(2 - 1).

2. The styrene-acrylate-epoxy graft copolymer for toner according to claim 1, wherein The styrene derivatives containing hydroxyl groups are 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.

3. The styrene-acrylate-epoxy graft copolymer for toner according to claim 1, wherein The acrylate monomers containing a tetrahydrofuran ring are selected from at least one of tetrahydrofurfuryl oxyethyl acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, and bis(tetrahydrofurfuryl) acrylate.

4. The styrene-acrylate-epoxy graft copolymer for toner according to claim 1, wherein, The branched alkyl acrylates are selected from at least one of 2 - isooctyl acrylate, 2 - ethylhexyl acrylate, isodecyl acrylate, and isobornyl acrylate.

5. The styrene-acrylate-epoxy graft copolymer for toner according to any one of claims 1-4, characterized in that, The styrene derivative containing hydroxyl groups is p - hydroxystyrene; and / or The acrylate monomer containing a tetrahydrofuran ring is tetrahydrofurfuryl oxyethyl acrylate; and / or The branched alkyl acrylate is 2 - ethylhexyl acrylate.

6. The styrene-acrylate-epoxy graft copolymer for toner according to claim 5, wherein, 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%.

7. A method for preparing a styrene-acrylate-epoxy graft copolymer for toner according to any one of claims 1-6, characterized in that, It includes the following steps: Under nitrogen protection, dissolve the styrene monomers, acrylate monomers, and monomers containing epoxy groups in an organic solvent, add a radical polymerization initiator, stir and react at 75 - 95 °C at a rotation speed of 200 - 300 r / min for 2 - 4 hours, then add a chain transfer agent, and continue to react at 70 - 80 °C at a rotation speed of 300 - 400 r / min for 1 - 3 hours; remove the solvent by vacuum distillation to obtain a crude product; Mix the obtained copolymer with an epoxy ring - opening catalyst, and react at 90 - 95 °C for 4 - 5 hours; then cool, precipitate, filter, and dry to obtain a styrene - acrylate - epoxy graft copolymer for toner.

8. The preparation method of the styrene-acrylate-epoxy graft copolymer for toner according to claim 7, characterized in that, The radical polymerization initiator is selected from at least one of benzoyl peroxide, azobisisobutyronitrile, and potassium persulfate, and the dosage is 0.5 - 2% of the total mass of the monomers.

9. The preparation method of the styrene-acrylate-epoxy graft copolymer for toner according to claim 7, characterized in that, The chain transfer agent is dodecyl mercaptan, and the dosage is 0.1 - 0.5% of the total mass of the monomers.

10. The preparation method of the styrene-acrylate-epoxy graft copolymer for toner according to claim 7, characterized in that, The epoxy ring - opening catalyst is triphenylphosphine or an amine compound, and the dosage is 2 - 5% of the molar amount of the epoxy groups.

Images