toner

Abstract

To provide toner which has the excellent low-temperature fixability, has the storing resistance in a severe environment and suppresses an image failure when performing the long-time image output under a high-temperature high-humidity environment after being stationarily installed in a severe environment.SOLUTION: There is provided toner having a base particle containing a binder resin and an outermost layer on the surface thereof. The binder resin contains a styrene-acrylic resin A having a specific monomer unit. The outermost layer contains a styrene-acrylic resin B. A plurality of recesses are formed on the surface of the toner particle. In the section analysis of the toner particle, when the thickness of the outermost layer is T (nm), the major axis of the recess is a (nm), the minor axis of the recess is b (nm), and the depth of the recess is d (nm), the number n of the recesses satisfying formulas (2) to (4) per 1 μm2 of the surface of the toner particle satisfies a formula (5). The formula (2): 50.0≤a≤400.0. The formula (3): 10.0≤b≤100.0. The formula (4): 0.7×T≤d≤1.5×T. The formula (5): 0.5≤n≤200.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a toner used in an electrophotographic image forming apparatus. [Background technology]

[0002] Conventionally, image forming devices using electrophotographic technology, such as copying machines and printers, have been required to be power-saving from the viewpoint of energy conservation. In addition, toner may be stored in harsh environments during transportation from the time it is manufactured until it is used by consumers, and it is necessary to continue providing high-quality images even after such transportation. In addition, in recent years, copying machines and printers have started to be used for light printing (print-on-demand applications that allow high-mix low-volume printing, from document editing to copying and bookbinding using a PC) that requires high image quality, and there is an increasing demand for faster speeds and higher image quality. In order to satisfy these requirements, the toner is required to have excellent low-temperature fixing properties, storage resistance that is not easily affected even when stored in harsh environments, and durability that enables high-quality images to be output even when used for a long period of time. Conventionally, toners with a core-shell structure, in which the surface of the toner base particles is coated with a shell resin, have been proposed in order to achieve both the low-temperature fixability, storage stability, and durability. Although core-shell toners have stable storage stability and durability, the outermost layer covers the entire surface of the toner particles, so that the entire toner needs to be melted in order to fix the toner to a medium such as paper in the fixing process, which can make fixing at low temperatures difficult. In particular, in high-speed machines, the time that the toner passes through the fixing nip is shorter, so even if the set temperature of the fixing device is the same, the amount of heat that the toner receives in the fixing process is smaller, making it more difficult to fix the toner at low temperatures. In other words, in high-speed machines where the print speed is faster with conventional toners, a method for further improving low-temperature fixability is required. Therefore, as a method for further improving the low-temperature fixing property of core-shell toners, toners that make it easier to melt the outermost layer of the toner surface, thereby making it easier to melt the entire toner quickly during fixing, are being considered. Patent Document 1 proposes a toner having an outermost layer made of a resin containing units derived from a monomer of a thermosetting resin and units derived from a thermoplastic resin, and having an outermost layer with adjusted hardness. Patent Document 2 proposes a toner having an outermost layer formed on the surface of a toner base particle, the outermost layer having a plurality of recesses that expose the toner base particle, as a toner having both excellent low-temperature fixing properties and storage stability. Patent Document 3 proposes a toner having multiple recesses on the surface of a toner base particle, the outermost layer being present both in the inner region of the recesses and in the outer region of the recesses, as a toner having both excellent low-temperature fixing properties and storage stability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-11077 A [Patent Document 2] JP 2015-141221 A [Patent Document 3] JP 2017-116712 A Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of the inventors' investigations, it was found that the toner described in Patent Document 1 has room for improvement in low-temperature fixability in high-speed machines because the outermost layer covers the entire toner surface. The toner described in Patent Document 2 is believed to be made to melt easily on the outermost layer of the toner surface by forming a plurality of recesses in the outermost layer that expose the toner base particles. However, the number and size of the recesses in the outermost layer have not been fully considered, and it has been found that there is room for improvement in storage durability in harsh environments where temperature and humidity change rapidly. In addition, it is presumed that the adhesion between the toner base particles and the outermost layer is insufficient, and it has been found that when the toner is left in a harsh environment and then used for a long time in a high-temperature and high-humidity environment, image defects occur due to contamination of members that is thought to be caused by peeling of the outermost layer. In the toner described in Patent Document 3, the outermost layer is present in both the inner and outer regions of the recesses, but it was found that the coating of the toner particle surface is non-uniform, and the toner base particles are exposed over a wide area. As a result, the shielding ability of the outermost layer as a shell is reduced, and it was found that there is room for improvement in storage resistance in harsh environments where temperature and humidity change rapidly. In addition, as with the toner described in Patent Document 2, it is presumed that the adhesion between the toner base particles and the outermost layer is insufficient, and it was found that when left to stand in a harsh environment and then used for a long time in a high-temperature and high-humidity environment, image defects occur due to member contamination thought to be caused by peeling of the outermost layer. The present invention provides a toner which has excellent low-temperature fixing properties and storage resistance in harsh environments, and which is less likely to cause image defects due to component contamination when images are output for a long period of time under a high-temperature and high-humidity environment after being left stationary in the harsh environment. [Means for solving the problem]

[0005] The toner of the present invention is a toner having toner particles each having a toner base particle containing a binder resin and an outermost layer present on a surface of the toner base particle, The binder resin contains a styrene-acrylic resin A, and the styrene-acrylic resin A has a monomer unit represented by the following formula (1),

[0006] [ka] (In formula (1), R 1represents a hydrogen atom or a methyl group, R 2 represents a linear alkyl group having 10 to 15 carbon atoms. the outermost layer present on the surface of the toner base particle contains a styrene-acrylic resin B, A plurality of recesses are formed on the surface of the toner particles, In a cross-sectional analysis of the toner particle observed with a transmission electron microscope, the thickness of the outermost layer is defined as T (nm), When the depressions in the toner particles are measured using a scanning probe microscope from the outermost surface of the outermost layer toward the center of the toner particle, the major axis of the depressions is a (nm), the minor axis of the depressions is b (nm), and the depth of the depressions is d (nm), The surface area of ​​the toner particles is 1 μm 2 The number n of the recesses per unit area satisfying the following formulas (2) to (4) satisfies the following formula (5). 50.0≦a≦400.0 Formula (2) 10.0≦b≦100.0 Formula (3) 0.7×T≦d≦1.5×T Formula (4) 0.5≦n≦200 Formula (5) Effect of the Invention

[0007] According to the present invention, a toner can be provided which has excellent low-temperature fixing properties and storage resistance in harsh environments, and which is less likely to cause image defects due to component contamination when left to stand in a harsh environment and then used for long-term image output in a high-temperature, high-humidity environment. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is a time chart of a heat cycle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The expressions "xx or more and xx or less" and "xx to xx" expressing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. In addition, "(meth)acrylic" means both acrylic and methacrylic.

[0010] <Background to the invention> The present inventors have conducted extensive research into a toner having recesses in the outermost layer of the toner surface, which has excellent low-temperature fixing properties and storage resistance in harsh environments, and which can provide high-quality images even when left to stand in a harsh environment and then image output is performed for a long period of time in a high-temperature, high-humidity environment.

[0011] To date, toners with recesses formed in the outermost layer of the toner surface have been considered as an approach to improving the low-temperature fixability of toners with an outermost layer. The inventors believe that this is because the recesses in the outermost layer of the toner surface represent areas where the toner base particles are exposed or areas where the outermost layer is thin, and the outermost layer plays a role in reducing the area present on the surface of the toner particles. In particular, in high-speed machines, the amount of heat that the toner receives in the fixing nip is small, so that toners with recesses in the outermost layer can be fixed to media such as paper even at low temperatures because the toner surface layer is more likely to melt.

[0012] However, when considering storage stability in a harsh environment where temperature and humidity change rapidly, toners having recesses on the outermost layer of the toner surface tend to have a reduced shielding ability as a shell of the outermost layer due to the thinning of the outermost layer and the tendency of the toner base particles to be exposed to the toner surface. In particular, when stored in a harsh environment where temperature and humidity change rapidly, toners having recesses are considered to be unable to suppress the low glass transition point component contained in the toner base particles from seeping out to the toner surface due to the reduced shielding ability. As a result, when the low glass transition point component seeps out to the toner surface, charging is not performed sufficiently even when the toner and the developing member are rubbed in the developing nip, and the amount of low charge toner increases, which tends to cause fogging.

[0013] Furthermore, it has been found that a new issue with toner having recesses in the outermost layer of the toner surface is that image defects due to component contamination occur when the toner is left to stand in a harsh environment and then used for a long period of time in a high-temperature, high-humidity environment.

[0014] The present inventors consider the reason why the above-mentioned image defects occur as follows. In the case of a toner having a recess in the outermost layer, the surface area of ​​the outermost layer increases, so that when the toner expands or contracts under the influence of temperature and humidity when the toner is left standing in a harsh environment where temperature and humidity change rapidly, the outermost layer tends to expand or contract more than the toner base particles. In particular, when the toner base particles and the outermost layer are made of different materials, the expansion rate and contraction rate are different, so that gaps are likely to occur at the interface between the toner base particles and the outermost layer. Then, when the toner is rubbed in the developing nip or the like due to the gaps generated at the interface between the toner base particles and the outermost layer, a part of the outermost layer of the toner surface layer is likely to peel off. Then, the present inventors consider that the outermost layer peeled off from the toner surface layer contaminates the developing member, so that the toner is not sufficiently charged in the developing nip, resulting in a decrease in density, or the outermost layer peeled off in the developing nip forms an aggregate, resulting in vertical streaks in a halftone image.

[0015] Although the outermost layer having recesses as in Patent Document 2 and Patent Document 3 improves low-temperature fixability, the recesses in the outermost layer are large, or the toner base particles are exposed to the toner surface in a large area, so that the shielding ability of the outermost layer is reduced, and the preservability when stored in a harsh environment tends to be reduced. In addition, when the toner base particles and the outermost layer are used for a long time in a high-temperature and high-humidity environment after storage in a harsh environment, gaps are likely to occur at the interface between the toner base particles and the outermost layer when stored in the harsh environment, because the resin compositions of the toner base particles and the outermost layer are significantly different, and image defects that are thought to be caused by contamination of components have occurred.

[0016] As a result of intensive research, the present inventors have found that the following configuration has better low-temperature fixing properties, has excellent storage stability even when stored in a harsh environment, and can suppress image defects caused by member contamination even when used for a long period of time in a high-humidity environment after storage in the harsh environment.

[0017] That is, the toner of the present invention is a toner having toner particles each having a toner base particle containing a binder resin and an outermost layer present on the surface of the toner base particle, The binder resin contains a styrene-acrylic resin A, and the styrene-acrylic resin A contains a monomer unit represented by the following formula (1),

[0018] [ka] (In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear alkyl group having 10 to 15 carbon atoms.

[0019] the outermost layer present on the surface of the toner base particle contains a styrene-acrylic resin B, A plurality of recesses are formed on the surface of the toner particles, In a cross-sectional analysis of the toner particle observed with a transmission electron microscope, the thickness of the outermost layer is defined as T (nm), When the depressions in the toner particles are measured using a scanning probe microscope from the outermost surface of the outermost layer toward the center of the toner particles, the major axis of the depressions is a (nm), the minor axis of the depressions is b (nm), and the depth of the depressions is d (nm), Surface area of ​​the toner particles is 1 μm 2 The number n of the recesses per unit area satisfying the following formulas (2) to (4) satisfies the following formula (5). 50.0≦a≦400.0 Formula (2) 10.0≦b≦100.0 Formula (3) 0.7×T≦d≦1.5×T Formula (4) 0.5≦n≦200 Formula (5)

[0020] <Mechanism by which the present invention exerts its effects> Here, the reason why the above-mentioned performance can be imparted by the toner base particles containing styrene-acrylic resin A including the monomer unit represented by formula (1), the outermost layer containing styrene-acrylic resin B, and controlling the number and size of the recesses on the toner surface will be described.

[0021] The present inventors have found that in a toner having recesses in the outermost layer of the toner surface, in order to suppress bleeding when stored in a harsh environment and to suppress peeling of the outermost layer when used for a long period of time in a high-temperature, high-humidity environment after storage in the harsh environment, the following points are important. (1-1) Increasing the affinity between the toner base particles and the outermost layer and increasing the adhesion between the toner base particles and the outermost layer makes the outermost layer less likely to peel off. (1-2) The outermost layer has minute recesses to reduce the area of ​​contact between toner particles when stored in harsh environments. (1-3) The outermost layer has minute recesses, which reduces gaps that occur at the interface between the toner base particles and the outermost layer when stored in a harsh environment, making the outermost layer less likely to peel off.

[0022] The above (1-1) is strongly influenced by the composition of the resin contained in the toner base particles and the outermost layer, and the compatibility between the toner base particles and the outermost layer. A toner having high affinity and adhesion to the toner base particles can suppress gaps that occur due to differences in the amount of expansion and contraction between the toner base particles and the outermost layer when stored in a harsh environment. Therefore, even when the toner is stored in a harsh environment and then used for a long time in a high-temperature and high-humidity environment, image defects caused by member contamination can be suppressed.

[0023] On the other hand, the above (1-2) and (1-3) are strongly influenced by the size and number of the recesses in the outermost layer. When the outermost layer has fine recesses, the area of ​​contact between toner particles can be reduced when stored in a harsh environment, improving storage stability. In addition, the outermost layer having fine recesses increases the flexibility of the outermost layer, thereby alleviating distortion caused by the difference in the amount of expansion and contraction between the toner base particles and the outermost layer when stored in a harsh environment, and reducing the gap. Therefore, the toner has excellent low-temperature fixability and excellent storage stability when stored in a harsh environment, and can suppress image damage caused by member contamination even when used for a long time in a high-temperature and high-humidity environment after storage in a harsh environment.

[0024] As described above, only by satisfying the above (1-1) to (1-3) can the toner have excellent low-temperature fixing property, excellent storage resistance when stored in a harsh environment, and suppress image damage caused by member contamination even when used for a long period of time in a high-temperature and high-humidity environment after storage in the harsh environment.

[0025] Specifically, in order to increase the affinity between the toner base particles and the outermost layer, the binder resin of the toner base particles contains a styrene-acrylic resin A having a monomer unit represented by the following formula (1), and the outermost layer of the toner base particles contains a styrene-acrylic resin B.

[0026] [ka] (In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a linear alkyl group having 10 to 15 carbon atoms.

[0027] The binder resin of the toner base particle contains styrene-acrylic resin A, and the outermost layer of the toner base particle contains styrene-acrylic resin B, so that the affinity between the toner base particle and the shell layer is increased. This is because the toner base particle and the outermost layer are made of a resin mainly composed of the same monomer. In addition, the styrene-acrylic resin A in the toner base particle has a monomer unit represented by the above formula (1), and the monomer unit represented by the above formula (1) present on the surface of the toner base particle does not crystallize, and the outermost layer is compatible with the monomer unit, improving the adhesion between the toner base particle and the outermost layer. The increased adhesion between the toner base particle and the outermost layer suppresses peeling of the outermost layer when the toner particles come into contact with each other, making it less likely that low density or vertical stripes will occur in halftone images.

[0028] Furthermore, during fixing, the monomer unit represented by the above formula (1) serves as a starting point for plasticizing the shell layer, which makes the shell layer on the surface of the toner easier to melt. As a result, the entire toner also melts quickly, improving low-temperature fixing properties in high-speed machines.

[0029] R in the above formula (1) 2 If the carbon number of R in the above formula (1) is less than 10, the glass transition point of the long-chain acrylic monomer portion increases, so that the plasticizing effect on the outermost layer decreases, and peeling of the outermost layer tends to be difficult to suppress. 2 If the carbon number is more than 15, the crystallinity of the long-chain acrylic monomer portion increases, so that the plasticizing effect on the outermost layer decreases, and peeling of the outermost layer tends to become difficult to suppress.

[0030] The outermost layer has minute recesses, and when the recesses on the toner surface are measured with a scanning probe microscope (hereinafter also referred to as SPM), the major axis of the recesses measured from the outermost surface of the outermost layer toward the center of the toner particle is a (nm), the minor axis of the recesses is b (nm), and the depth of the recesses is d (nm), 2 The number n of recesses per unit area satisfying the above formulas (2) to (4) needs to satisfy the following formula (5). 50.0≦a≦400.0 Formula (2) 10.0≦b≦100.0 Formula (3) 0.7×T≦d≦1.5×T Formula (4) 0.5≦n≦200 Formula (5)

[0031] By controlling the number n of recesses satisfying the above formulas (2) to (4) so ​​as to fall within the above formula (5), the area where the toner base particles are exposed or the area where the outermost shell layer is thin can be increased, and the area where the outermost layer covers the surface of the toner particles can be reduced. As a result, the toner surface layer becomes easier to melt, and the entire toner also melts quickly, improving low-temperature fixability in high-speed machines.

[0032] In addition, when the toner surface has minute recesses that satisfy the above formulas (2) and (3), the contact area between toner particles can be reduced when stored in a harsh environment, improving storage durability. Furthermore, when the toner surface has minute recesses that satisfy the above formulas (2) and (3), the flexibility of the outermost layer is increased, and distortion caused by the difference in the amount of expansion and contraction between the toner base particles and the outermost layer when stored in a harsh environment can be alleviated. As a result, image defects caused by member contamination can be suppressed.

[0033] When the number n of the recesses is less than 0.5, low-temperature fixability cannot be obtained. When the number n of the recesses is more than 200, storage stability in a harsh environment cannot be obtained, or when toner particles come into contact with each other, the strength of the outermost layer is weakened, so that a part of the outermost layer is easily peeled off. From the viewpoints of low-temperature fixability, storage stability in a harsh environment, and member contamination, the number n of the recesses is preferably 10 to 180.

[0034] The number of the recesses can be controlled by the concentration of the dispersant particles attached to the toner base particles when forming the outermost layer, or the heating temperature when forming the outermost layer. Specifically, the number n of the recesses tends to increase as the concentration of the dispersant particles is increased or the heating temperature when forming the outermost layer is increased.

[0035] The major axis a of the recess is 50.0 nm or more and 400.0 nm or less, and preferably 80.0 nm or more and 300.0 nm or less. The minor axis b of the recess obtained by the same measurement is 10.0 nm or more and 100.0 nm or less, and preferably 20.0 nm or more and 80.0 nm or less.

[0036] When the major axis a of the recess is less than 50.0 nm, the low-temperature fixing property tends to deteriorate. When the minor axis b of the recess is less than 10.0 nm, the low-temperature fixing property also tends to deteriorate. On the other hand, when the major axis a of the recess is more than 400.0 nm, the storage stability in a harsh environment tends to deteriorate and image damage caused by peeling of the outermost layer tends to occur. When the minor axis b of the recess is more than 100.0 nm, the storage stability in a harsh environment tends to deteriorate and image damage caused by peeling of the outermost layer tends to occur.

[0037] The major axis a and minor axis b of the recesses can be controlled by the major axis and minor axis of the dispersant particles that are attached to the toner base particles when the outermost layer is formed, and the major axis and minor axis of the dispersant particles can be controlled by the reaction temperature, pH, shear conditions, etc., when the dispersant particles are produced. Specifically, the major axis a and minor axis b of the recesses tend to become smaller as the reaction temperature is higher, the pH is lower, and the shear conditions are stronger when the dispersant particles are produced.

[0038] The thickness T (nm) of the outermost layer in a cross-sectional analysis of the toner observed with a transmission electron microscope (hereinafter also referred to as TEM) and the depth d (nm) of the recesses on the toner surface obtained by measuring the recesses on the toner surface from the outermost surface of the outermost layer toward the center of the toner particle using a scanning probe microscope must satisfy the following formula (4). 0.7×T≦d≦1.5×T Formula (4) Preferably, d (nm) is equal to or greater than 0.8×T and equal to or less than 1.1×T.

[0039] When d is 0.7×T or more, the area of ​​the toner base particles present in the recesses increases, so that low-temperature fixability tends to be improved. On the other hand, when d is 1.5×T or less, the recesses are not too deep, so that the surface of the outermost layer is less likely to be distorted, and the outermost layer having the recesses is less likely to peel off even when the toner particles come into contact with each other, so that image defects caused by member contamination are less likely to occur.

[0040] The depth d of the recesses can be controlled by the concentration of dispersant particles attached to the toner base particles when forming the outermost layer, the amount of material added to form the outermost layer, etc. Specifically, the depth d of the recesses tends to increase as the concentration of dispersant particles or the amount of material added to form the outermost layer increases.

[0041] The outermost layer present on the surface of the toner base particle contains styrene-acrylic resin B, and it is preferred that the styrene-acrylic resin B does not contain the monomer unit represented by the above formula (1).

[0042] Since the monomer unit represented by the above formula (1) has the effect of making styrene-acrylic resins compatible, by not including the monomer unit represented by the above formula (1) in styrene-acrylic resin B, it is possible to suppress a decrease in the glass transition point of the outermost layer. Therefore, even if the temperature inside the printer body rises due to long-term use in a high-temperature, high-humidity environment, external additives are less likely to be embedded, and a decrease in the fluidity of the toner can be suppressed. As a result, peeling of the outermost layer when toner particles come into contact with each other is less likely to occur, and suppressing peeling of the outermost layer makes it less likely that image defects caused by contamination of components will occur.

[0043] In the present invention, the average circularity of the toner particles is preferably 0.920 or more and 0.960 or less.

[0044] When the average circularity of the toner particles is within the above range, the toner particles are likely to come into contact with each other, but large recesses are formed on the toner surface, so that peeling of the outermost layer present in the large recesses can be suppressed. As a result, even when outputted for a long time under a high temperature and high humidity environment, a large amount of the outermost layer remains in the large recesses formed on the toner particle surface, so that contamination of components caused by the peeled outermost layer is suppressed, and image defects caused by contamination of components are less likely to occur.

[0045] The average circularity of the toner particles can be adjusted to fall within the above range by adjusting the production method and production conditions of the toner particles.

[0046] The thickness T (nm) of the outermost layer is preferably 5.0 nm or more and 100.0 nm or less.

[0047] When the thickness T (nm) of the outermost layer is 5.0 nm or more, the durability and storage resistance in a harsh environment tend to be improved, whereas when the thickness T (nm) of the outermost layer is 100.0 nm or less, the low-temperature fixability tends to be improved.

[0048] The thickness T (nm) of the outermost layer can be controlled by the amount of material added to form the outermost layer, etc. Specifically, the thickness T (nm) of the outermost layer tends to increase as the amount of material added to form the outermost layer increases.

[0049] The thickness T (nm) of the outermost layer is more preferably 10.0 nm or more and 60.0 nm or less from the viewpoint of achieving both low-temperature fixability, durability, and storage resistance in a harsh environment.

[0050] Next, the constituent materials of the toner base particles according to the present invention will be described.

[0051] <Binding resin> The binder resin of the toner base particles contains styrene-acrylic resin A, and the content of styrene-acrylic resin A in the toner particles is preferably 30.0% by mass or more and 90.0% by mass or less.

[0052] When the content of styrene-acrylic resin A is 30.0% by mass or more, the adhesion between the toner base particles and the outermost layer is improved, and peeling of the outermost layer is reduced, which tends to improve the suppression of vertical streaks in halftone images. This is because the outermost layer contains styrene-acrylic resin B, and the toner base particles and the outermost layer contain resins made of monomers of the same composition, which increases the affinity and improves the adhesion between the toner base particles and the outermost layer. On the other hand, the upper limit of the content of styrene-acrylic resin A in the toner particles is not particularly limited, but it is preferably 90.0% by mass or less.

[0053] The styrene-acrylic resin A preferably contains the monomer unit represented by the formula (1) in an amount of 1.0% by mass or more and 15.0% by mass or less.

[0054] When the styrene-acrylic resin A has 1.0% by mass or more of the monomer unit represented by formula (1), the monomer unit represented by formula (1) present on the surface of the toner base particle plasticizes the styrene-acrylic resin B of the outermost layer, which tends to improve the adhesion between the toner base particle and the outermost layer and improve durability. Furthermore, the monomer unit represented by formula (1) becomes the starting point for plasticizing the outermost layer during fixing, which makes the surface layer of the toner particle more likely to melt. This tends to improve durability and low-temperature fixability. On the other hand, when the styrene-acrylic resin A has 15.0% by mass or less of the monomer unit represented by formula (1), the glass transition point of the toner base particle can be suppressed from decreasing, which tends to improve storage stability in harsh environments.

[0055] The styrene-acrylic resin A preferably has a monomer unit represented by the following formula (6).

[0056] [ka] (In formula (6), R 1 represents a hydrogen atom or a methyl group, R 2 represents a linear alkyl group having 12 carbon atoms.

[0057] The monomer represented by the above formula (6) is lauryl (meth)acrylate [lauryl (meth)acrylate], and when the styrene-acrylic resin A contains the monomer unit represented by formula (6), the monomer unit represented by formula (6) present on the surface of the toner mother particle tends to plasticize the styrene-acrylic resin B of the outermost layer while suppressing the drop in the glass transition point of the toner mother particle. This is believed to be because the monomer unit represented by formula (6) does not crystallize within the toner mother particle and has high compatibility with the styrene-acrylic resin. This further improves the adhesion between the toner mother particle and the outermost layer, and tends to suppress image defects caused by member contamination.

[0058] In a preferred embodiment, the styrene-acrylic resin A is a copolymer of one or more styrene monomers and one or more (meth)acrylic monomers. In order to synthesize the styrene-acrylic resin A, for example, the following styrene monomers and (meth)acrylic monomers can be suitably used.

[0059] Suitable examples of styrene-based monomers include styrene, alkylstyrenes (e.g., α-methylstyrene, p-ethylstyrene, 4-tert-butylstyrene, etc.), p-hydroxystyrene, m-hydroxystyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.

[0060] Suitable examples of the (meth)acrylic monomer include (meth)acrylic acid, (meth)acrylonitrile, (meth)acrylic acid alkyl esters, and (meth)acrylic acid hydroxyalkyl esters.

[0061] Suitable examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-butyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0062] Suitable examples of the (meth)acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0063] It is also a preferred embodiment that the binder resin of the toner base particles contains a polyester resin. The content of the polyester resin in the binder resin may be, for example, 1% by mass or more and 10% by mass or less.

[0064] The polyester resin can be obtained by condensation polymerization or co-condensation polymerization of a conventionally known divalent or trivalent or higher carboxylic acid component and a divalent or trivalent or higher alcohol component.

[0065] As the divalent, trivalent or higher carboxylic acid component, for example, an ester derivative (for example, an acid halide, an acid anhydride, or a lower alkyl ester) may be used. Here, the lower alkyl means an alkyl group having 1 to 6 carbon atoms.

[0066] Examples of the divalent carboxylic acid component that can be used include dibasic acids such as succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, malonic acid, and dodecenylsuccinic acid, as well as their anhydrides or lower alkyl esters, and aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0067] As the trivalent or higher carboxylic acid component, for example, 2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, and lower alkyl groups thereof can be used.

[0068] These carboxylic acid components may be used alone or in combination of two or more.

[0069] Suitable examples of the dihydric or trihydric or higher alcohol component include diols, bisphenols, and trihydric or higher alcohols.

[0070] Examples of the dihydric alcohol component include the following compounds: alkylene glycols (ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol); alkylene ether glycols (polyethylene glycol and polypropylene glycol); alicyclic diols (1,4-cyclohexanedimethanol); bisphenols (bisphenol A); and alkylene oxide (ethylene oxide and propylene oxide) adducts of alicyclic diols.

[0071] The alkyl moiety of the alkylene glycol and the alkylene ether glycol may be linear or branched, and branched alkylene glycols are also preferably used.

[0072] Examples of the trihydric or higher alcohol component include the following compounds: glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0073] These alcohol components may be used alone or in combination of two or more.

[0074] For the purpose of adjusting the acid value or hydroxyl value, monovalent acids such as acetic acid and benzoic acid, and monovalent alcohols such as cyclohexanol and benzyl alcohol can also be used as necessary.

[0075] The method for synthesizing the polyester resin is not particularly limited, and for example, a transesterification method or a direct polycondensation method can be used alone or in combination.

[0076] <Wax> The toner base particles may contain wax. As the wax, known waxes can be used.

[0077] Specific examples include petroleum waxes and their derivatives, such as paraffin wax, microcrystalline wax, and petroleum waxes represented by petrolactam, montan wax and its derivatives, hydrocarbon waxes and their derivatives produced by the Fischer-Tropsch process, polyolefin waxes and their derivatives, such as polyethylene, natural waxes and their derivatives, such as carnauba wax and candelilla wax, etc. The derivatives also include oxides, block copolymers with vinyl monomers, and graft modified products.

[0078] Also usable are alcohols such as higher aliphatic alcohols; aliphatic acids such as stearic acid and palmitic acid or their acid amides, esters and ketones; hydrogenated castor oil and its derivatives, vegetable waxes and animal waxes.

[0079] These waxes may be used alone or in combination of two or more kinds.

[0080] Among these, polyolefin, hydrocarbon wax produced by the Fischer-Tropsch process, or petroleum wax is preferably used since it tends to improve developability and transferability.

[0081] An antioxidant may be added to these waxes as long as it does not affect the effects of the present disclosure of the toner.

[0082] The content of the wax is preferably 1.0 part by mass or more and 30.0 parts by mass or more with respect to 100.0 parts by mass of the binder resin. The melting point of the wax is preferably 30° C. or more and 120° C. or less, more preferably 60° C. or more and 100° C. or less.

[0083] <Coloring agent> The toner base particles may contain a colorant. Known pigments and dyes can be used as the colorant. Pigments are preferred as the colorant because they have excellent weather resistance.

[0084] Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds.

[0085] Specific examples include: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62 and 66.

[0086] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

[0087] Specific examples include: CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254, and CI Pigment Violet 19.

[0088] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

[0089] Specific examples include: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191 and 194.

[0090] Examples of black colorants include carbon black and those toned to black using the above-mentioned yellow, magenta and cyan colorants.

[0091] These colorants may be used alone or in combination of two or more kinds, and may also be used in the form of a solid solution.

[0092] The content of the colorant is preferably 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0093] <Charge control agents and charge control resins> The toner base particles may contain at least one selected from the group consisting of a charge control agent and a charge control resin.

[0094] As the charge control agent, a known one can be used, and a charge control agent that has a high triboelectric charging speed and can stably maintain a constant triboelectric charge amount is particularly preferred. Furthermore, when the toner particles are produced by a suspension polymerization method, a charge control agent that has low polymerization inhibition properties and is substantially free of solubilized matter in an aqueous medium is particularly preferred.

[0095] The charge control agent may be one that controls the toner to be negatively charged or one that controls the toner to be positively charged.

[0096] Examples of toners that control the toner to be negatively charged include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, quaternary ammonium salts, calixarenes, and charge control resins.

[0097] The charge control resin may be a polymer or copolymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group. As the polymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group, a polymer containing a sulfonic acid group-containing acrylamide monomer or a sulfonate group-containing methacrylamide monomer in a copolymerization ratio of 2% by mass or more is preferable, and a polymer containing a sulfonic acid group-containing methacrylamide monomer in a copolymerization ratio of 5% by mass or more is more preferable.

[0098] The charge control resin preferably has a glass transition temperature (Tg) of 35° C. or more and 90° C. or less, a peak molecular weight (Mp) of 10,000 or more and 30,000 or less, and a weight average molecular weight (Mw) of 25,000 or more and 50,000 or less. When used, it is possible to impart preferable triboelectric charging characteristics without affecting the thermal characteristics required for the toner particles. Furthermore, since the charge control resin contains a sulfonic acid group, for example, the dispersibility of the charge control resin itself in the polymerizable monomer composition and the dispersibility of the colorant are improved, and the coloring power, transparency, and triboelectric charging characteristics can be further improved.

[0099] These charge control agents or charge control resins may be used alone or in combination of two or more.

[0100] The content of the charge control agent or charge control resin is preferably 0.01 parts by mass or more and 20.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 10.0 parts by mass or less, relative to 100.0 parts by mass of the binder resin.

[0101] Next, the outermost layer formed on the surface of the toner base particle will be described.

[0102] <Outermost layer> The outermost layer preferably contains a styrene-acrylic resin B, and the styrene-acrylic resin B preferably has a monomer unit represented by the following formula (7).

[0103] [ka] (In formula (7), R 1 represents a hydrogen atom or a methyl group, R 2 represents an alkyl group having 1 to 8 carbon atoms.

[0104] When the styrene-acrylic resin B has a monomer unit represented by formula (7), the flexibility of the outermost layer is increased, and therefore, when stored in a harsh environment, distortion caused by the difference in the amount of expansion or contraction between the toner base particles and the outermost layer can be alleviated, and the occurrence of gaps can be suppressed. Therefore, the toner has excellent preservability when stored in a harsh environment, and image defects caused by contamination of components can be suppressed even when used for a long time in a high-temperature and high-humidity environment after storage in the harsh environment.

[0105] The styrene-acrylic resin B preferably contains from 1.0% by mass to 40.0% by mass of the monomer unit represented by formula (7).

[0106] When the styrene-acrylic resin B contains 1.0% by mass or more of the monomer unit represented by formula (7), the flexibility of the outermost layer is increased, and therefore, when stored in a harsh environment, the distortion caused by the difference in the amount of expansion or contraction between the toner base particles and the outermost layer tends to be alleviated, and the occurrence of gaps tends to be suppressed.When the styrene-acrylic resin B contains 40.0% by mass or less of the monomer unit represented by formula (7), the decrease in the glass transition point of the outermost layer can be suppressed, and therefore, the storage stability in a harsh environment tends to be further improved.

[0107] As the monomers for synthesizing the styrene-acrylic resin B, the same monomers as the styrene-based monomers and (meth)acrylic monomers for synthesizing the styrene-acrylic resin A described above can be suitably used.

[0108] <Inorganic particles such as silica as external additives> The toner particles may be used as they are as a toner, but may also be used as a toner by mixing with an external additive, etc., if necessary, and attaching the additive to the surface.

[0109] The addition of silica particles as an external additive to the toner particles can improve the fluidity and chargeability. The content of the silica particles is preferably 0.1 parts by mass or more and 4.0 parts by mass or less, more preferably 0.2 parts by mass or more and 3.5 parts by mass or less, relative to 100 parts by mass of the toner particles.

[0110] The toner surface may contain inorganic particles other than the silica particles described above, such as titanium oxide particles, alumina particles, silica particles having a primary particle diameter of less than 40.0 nm, or double oxide particles thereof.

[0111] Examples of silica particles include dry silica or fumed silica produced by vapor phase oxidation of silicon halides, and wet silica produced from water glass. Among them, silica particles with few silanol groups on the surface and inside and with low Na2O, SO3 2- The dry silica may be a composite fine particle of silica and another metal oxide, which is produced by using a metal halide compound such as aluminum chloride or titanium chloride together with a silicon halide compound in the production process.

[0112] From the viewpoints of the charge amount of the toner, environmental stability, characteristics in a high humidity environment, developability, transferability, and the like, it is more preferable to use silica particles that have been subjected to a hydrophobic treatment (also called hydrophobic silica) as the silica particles.

[0113] Examples of the treatment agent for hydrophobizing the silica particles include unmodified silicone varnish, various modified silicone varnishes, unmodified silicone oil, various modified silicone oils, silane compounds, silane coupling agents, other organosilicon compounds and organotitanium compounds, etc. These treatment agents may be used alone or in combination of two or more.

[0114] Among them, silica particles treated with silicone oil are preferred, and more preferably, hydrophobic silica treated with silicone oil simultaneously with or after hydrophobizing silica particles with a silane coupling agent is preferred from the viewpoint of maintaining a high charge amount of toner particles even in a high humidity environment and reducing selective developability.

[0115] <Toner manufacturing method> The production of the toner of the present invention includes the following steps. (a) A step of adhering dispersant particles to the surface of toner base particles. (b) A step of forming an outermost layer on the surface of the toner base particles after the dispersant particles are attached. (c) removing the dispersant particles from the surfaces of the toner base particles after forming the outermost layer.

[0116] By the above operations (a) to (c), the dispersant particles are attached to the surface of the toner base particles, and a material for forming an outermost layer is added to the dispersion liquid containing the toner base particles, thereby forming an outermost layer on the surface of the toner base particles. The medium used in forming the outermost layer is preferably an aqueous medium from the viewpoint of preventing the components contained in the toner base particles from dissolving into the medium.

[0117] First, in step (a), dispersant particles are attached to the surface of the toner base particles. Examples of methods for attaching dispersant particles to the surface of the toner base particles include a method in which the toner base particles are mechanically dispersed in an aqueous medium using a device with a strong stirring function, and then a dispersant is added, and a method in which the toner base particles are added to an aqueous medium containing a dispersant. Among these, the method in which the toner base particles are added to an aqueous medium containing a dispersant is preferred because the toner base particles can be uniformly dispersed in the aqueous medium with little power.

[0118] As the dispersant, polymer dispersants, surfactants, resin particles, inorganic particles, etc. can be used without any particular restrictions. Among them, inorganic particles are preferably used in order to prevent surface modification of the toner base particles and to highly disperse the toner base particles in a medium (particularly an aqueous medium). As the inorganic particles, for example, particles of inorganic compounds such as sodium phosphate and calcium chloride can be used.

[0119] The number average particle diameter of the dispersant particles is preferably 30 nm to 350 nm, more preferably 50 nm to 200 nm. The amount of the dispersant particles used is preferably 0.3 parts by mass to 30.0 parts by mass, more preferably 0.5 parts by mass to 10.0 parts by mass, based on 100 parts by mass of the toner base particles.

[0120] In an aqueous medium containing dispersant particles, the dispersant particles are uniformly dispersed, so that the dispersant particles can be attached to the surfaces of the toner base particles by adding the toner base particles and mechanically mixing them with a stirring device.

[0121] When the toner base particles are produced by the suspension polymerization method, an aqueous dispersion of the toner base particles having dispersant particles attached to the surfaces thereof is produced in the production process, and therefore the aqueous dispersion of the toner base particles can be used as it is as the toner base particle dispersion. In other words, the process of producing the toner base particles can include a process of attaching dispersant particles to the surfaces of the toner base particles.

[0122] Next, in the step (b), an outermost layer is formed on the surface of the toner base particles. For example, the outermost layer can be formed on the surface of the toner base particles by adding a material for the outermost layer to the toner base particle dispersion liquid.

[0123] The material for the outermost layer may be, for example, the above-mentioned thermoplastic resin or the above-mentioned thermosetting resin. When a thermoplastic resin is used as the material for the outermost layer, the outermost layer can be formed, for example, by mixing a dispersion of the thermoplastic resin with the toner base particles, attaching the thermoplastic resin to the surface of the toner base particles in an aqueous medium, and heating the mixture. When a thermosetting resin is used as the material for the outermost layer, a monomer constituting the thermosetting resin can be mixed with the toner base particles, and a reaction can be promoted on the surface of the toner base particles in an aqueous medium by heating the mixture, thereby forming the outermost layer.

[0124] The outermost layer covers the area where the dispersant particles adhered in step (a) and is formed in the form of a film on a part or the entire surface of the toner base particle.

[0125] The temperature when forming the outermost layer is preferably from 40° C. to 90° C., more preferably from 50° C. to 80° C. By forming the outermost layer at a temperature in this range, the formation of the outermost layer proceeds smoothly.

[0126] In the step (c), after the outermost layer is formed, the dispersant particles are removed from the surface of the toner base particles. When the dispersant particles are inorganic particles, for example, the inorganic particles can be dissolved using an acid and then filtered to remove them from the surface of the toner base particles. By removing the dispersant particles, the shape of the dispersant particles can be formed in a concave shape in the outermost layer.

[0127] Thereafter, dispersion in water and filtration are repeated as necessary to obtain toner particles having recesses on their surfaces.

[0128] <Various measurement methods, etc.> Various measurement methods etc. are described below.

[0129] <Method of measuring the major axis, minor axis, depth and number of recesses on the surface of a toner particle> Using a scanning probe microscope (SPM), the recesses on the surface of the toner particles are observed by the following method.

[0130] The cantilever used for the measurement is a Seiko Instruments SI-DF20 (back side Al coated) in dynamic force mode. Before the measurement, the SPM is used after checking the accuracy in the depth direction using a pattern sample for accuracy inspection (100 nm ± 5 nm).

[0131] First, a conductive double-sided tape is attached to the sample stage, and toner particles are sprayed onto it. Excess toner particles are then removed from the sample stage by air blowing. The sample is then polished to a 1 μm x 1 μm (1 μm) surface with an SPM (product name: E-sweep, manufactured by Hitachi High-Tech Science Corporation). 2 ) and observe the depressions in the outermost layer.

[0132] After the measurement, the slope of the obtained 1 μm×1 μm measurement data is corrected, and then the surface average roughness is calculated. The surface average roughness means the arithmetic mean value of the depth of the recesses when measured from the outermost surface of the outermost layer toward the center of the toner particle in 1 μm×1 μm, and is defined as the depth d1 (nm) of the recesses of the outermost layer in this disclosure. The depths d1 to d of the recesses of 50 toner particles were calculated by the above method. 50 Find d1~d 50 The arithmetic mean value of these values ​​is taken as the depth d (nm) of the recess.

[0133] The number n of recesses that satisfy the above formulas (2) to (4) is calculated as follows. The measurement data obtained by the above measurement after tilt correction is output, and the major axis a (nm) of the recesses in 1 μm×1 μm, the minor axis b (nm) of the recesses, and the depth d (nm) of the recesses are measured. Then, the number n1 of recesses that satisfy the above formulas (2) to (4) per 1 μm×1 μm of the toner particle surface is counted. The numbers n1 to n of recesses that satisfy the above formulas (2) to (4) for 50 toner particles are calculated by the above method. 50 , and the arithmetic mean value of each is taken as the number n of recesses.

[0134] The major axis A of the recess and the minor axis B of the recess are calculated as follows. The measurement data after the inclination correction obtained by the above measurement is output, and the arithmetic average values ​​of the major axis and minor axis of the recess per 1 μm×1 μm of the toner particle surface are calculated and are designated as the major axis a1 and the minor axis b1 of the recess, respectively. 50 and the minor axis of the recess b1 to b 50 The arithmetic mean values ​​are defined as the major axis a and the minor axis b of the recess.

[0135] <Method of Obtaining Toner Particles by Removing External Additives from Toner> When measuring the recesses on the surface of a toner having an external additive attached to its surface, the external additive is removed by the following procedure to obtain toner particles, and then the recesses are measured by the above method.

[0136] Add 160 g of sucrose (Kishida Chemical Co., Ltd.) to 100 mL of ion-exchanged water and dissolve in a hot water bath to prepare a 61.5% sucrose aqueous solution. Place 31.0 g of the above sucrose concentrated solution and 6 g of Contaminon N (product name) (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments made of nonionic surfactants, anionic surfactants, and organic builders, manufactured by Wako Pure Chemical Industries, Ltd.) in a centrifuge tube to prepare a dispersion. Add 1.0 g of toner to this dispersion and break up the toner clumps with a spatula or the like.

[0137] Shake the centrifuge tube in a shaker at 300 strokes per minute (spm) for 20 minutes. After shaking, transfer the solution to a glass tube for a swing rotor (50 mL) and separate in a centrifuge at 3,500 rpm for 30 minutes.

[0138] Visually check that the toner particles and the aqueous solution are sufficiently separated, and collect the toner particles that have separated to the top layer with a spatula, etc. The collected toner particles are filtered through a vacuum filter and then dried in a dryer for at least one hour. The dried product is crushed with a spatula to obtain toner particles.

[0139] <Measuring method for the thickness T of the outermost layer> Using a transmission electron microscope (TEM), the cross section of a toner particle is observed by the following method.

[0140] First, toner particles are thoroughly dispersed in a room temperature curing epoxy resin, and then cured for 2 days in an atmosphere at 40°C. From the obtained cured product, a 50 nm thick flake-shaped sample is cut out using a microtome equipped with a diamond blade, and ruthenium staining is performed using a vacuum staining device (manufactured by Filgen). Then, this sample is magnified 100,000 times with a TEM (trade name: electron microscope Tecnai TF20XT, manufactured by FEI) to observe the cross section of the toner particle. The thickness (unit: nm) of the outermost layer at four randomly selected points on one toner particle is measured.

[0141] The cross sections of 50 toner particles are observed by the above method, and the arithmetic average value of a total of 200 particles is taken as the thickness T (nm).

[0142] <Method of measuring weight average particle size (D4) of toner and toner particles> The weight average particle diameter (D4) of the toner is measured as follows.

[0143] The measurement device used is a precision particle size distribution measurement device using the pore electrical resistance method, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.). The measurement is performed with an effective measurement channel count of 25,000.

[0144] The aqueous electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter).

[0145] Before performing measurements and analysis, the dedicated software is set up as follows.

[0146] In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count number in the control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard particle 10.0 μm" (Beckman Coulter). Press the "Threshold / Noise level measurement button" to automatically set the threshold and noise level. In addition, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

[0147] In the "Pulse to particle size conversion setting" screen of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

[0148] The specific measurement method is as follows. (1) Pour 200 mL of electrolyte solution into a 250 mL round-bottom glass beaker made exclusively for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "Aperture tube flush" function of the dedicated software to remove dirt and air bubbles from inside the aperture tube. (2) Put 30 mL of the electrolyte solution into a 100 mL flat-bottom glass beaker. Add 0.3 mL of a solution of "Contaminon N" (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments made from a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted 3 times with ion-exchanged water as a dispersant. (3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetora150" (manufactured by Nikkaki Bios Co., Ltd.) that has two built-in oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees, and has an electrical output of 120 W. Place 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank, and add 2 mL of Contaminon N to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the electrolyte solution in the beaker is maximized. (5) While the electrolyte solution in the beaker in (4) is irradiated with ultrasonic waves, 10 mg of toner particles are added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion treatment is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10°C or higher and 40°C or lower. (6) Using a pipette, the electrolyte solution (5) in which the toner particles are dispersed is dropped into the round-bottom beaker (1) placed in the sample stand, and the measurement concentration is adjusted to 5%. Then, measurements are continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software that comes with the device, and the weight average particle diameter (D4) is calculated. Note that when the dedicated software is set to Graph / Volume%, the "Average diameter" on the "Analysis / Volume Statistics (Arithmetic Mean)" screen is the toner weight average particle diameter (D4).

[0149] The weight average particle diameter (D4) of the toner particles is also measured in the same manner as above.

[0150] <Method for measuring the average circularity of toner particles> The average circularity of the toner particles is measured using a flow type particle image analyzer, "FPIA-3000" (manufactured by Sysmex Corporation), under the measurement and analysis conditions during the calibration work.

[0151] Add an appropriate amount of surfactant and alkylbenzene sulfonate as a dispersant to 20 mL of ion-exchanged water, then add 0.05 g of the measurement sample, and disperse for 2 minutes using a tabletop ultrasonic cleaner disperser (product name: VS-150, manufactured by Vervoclear Co., Ltd.) with an oscillation frequency of 50 kHz and an electrical output of 150 watts to obtain a dispersion for measurement. At this time, cool the dispersion appropriately so that the temperature is between 10°C and 40°C.

[0152] For the measurement, the flow type particle image analyzer equipped with a high magnification objective lens (20x) is used, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) is used as the sheath liquid. The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image analyzer, and 3000 toner particles (particles) are measured in HPF measurement mode and total count mode, the binarization threshold during particle analysis is set to 85%, the analyzed particle diameter is limited to a circle equivalent diameter of 1.98 μm to 36.69 μm, and the average circularity of the toner particles is obtained.

[0153] Before starting the measurement, automatic focus adjustment is performed using standard latex particles. After that, it is preferable to perform focus adjustment every 2 hours from the start of the measurement.

[0154] (Method of separating external additives from toner surface) When a toner having an external additive added to its surface is used as a measurement sample, toner particles from which the external additive has been removed can also be obtained by the following separation method.

[0155] (For non-magnetic toner) Add 160 g of sucrose (Kishida Chemical) to 100 mL of ion-exchanged water and dissolve in a hot water bath to prepare a concentrated sucrose solution. Place 31 g of the concentrated sucrose solution and 6 mL of Contaminon N (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, pH 7, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) in a centrifuge tube to prepare a dispersion. Add 1 g of toner to this dispersion and break up the toner clumps with a spatula or the like.

[0156] The centrifugation tube is placed in an Iwaki Sangyo KM Shaker (model: V.SX) and shaken for 20 minutes at 350 reciprocations per minute. After shaking, the solution is transferred to a glass tube (50 mL) for a swing rotor and centrifuged at 3,500 rpm for 30 minutes.

[0157] After centrifugation, the toner particles are in the top layer of the glass tube, and the silica fine particles are in the aqueous solution in the lower layer. The aqueous solution in the lower layer is collected and centrifuged repeatedly as necessary. After sufficient separation, the dispersion is dried and the silica fine particles are collected. The toner particles in the upper layer are collected and filtered, and washed with 2 L of ion-exchanged water heated to 40°C, and the washed toner particles are taken out.

[0158] (For magnetic toner) A dispersion medium is prepared by adding 6 mL of Contaminon N (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, pH 7, manufactured by Wako Pure Chemical Industries, Ltd.) to 100 mL of ion-exchanged water. 5 g of toner is added to this dispersion medium and dispersed for 5 minutes using an ultrasonic disperser (As One Corporation VS-150). After that, the mixture is set in a "KM Shaker" (model: V.SX) manufactured by Iwaki Sangyo Co., Ltd. and shaken for 20 minutes at 350 back and forth strokes per minute.

[0159] The toner particles are then restrained using a neodymium magnet. Because silica fine particles are present in the upper layer of the aqueous solution, the upper layer of the aqueous solution is collected and magnetic separation is repeated as necessary. After sufficient separation, the dispersion is dried and the silica fine particles are collected. The toner particles that have been restrained using a neodymium magnet are then collected. The toner particles are washed with 2 L of ion-exchanged water heated to 40°C, and the washed toner particles are taken out.

[0160] <Method for measuring volume average diameter of particles in thermoplastic dispersion> The volume average particle size of the particles in the thermoplastic resin dispersion is measured using a Zetasizer Nano-ZS (manufactured by MALVERN).

[0161] First, prepare a measurement sample by diluting the thermoplastic resin dispersion to be measured with water so that the solid-liquid ratio is 0.10% by mass (±0.02% by mass), collect it in a quartz cell, and place it in the measurement section. Enter the refractive index of the thermoplastic resin, the refractive index and viscosity of the dispersion solvent as measurement conditions, and measure in the range of 0.3 nm to 10.0 μm.

[0162] <Method of measuring glass transition temperature (Tg)> The glass transition temperature (Tg) of the outermost layer material, the toner base particles, etc. is measured using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments) in accordance with ASTM D3418-82.

[0163] The melting points of indium and zinc are used for temperature correction of the device detection section, and the heat of fusion of indium is used for heat correction.

[0164] Specifically, 10 mg of a sample is weighed out and placed in an aluminum pan. An empty aluminum pan is used as a reference, and measurements are performed at a temperature rise rate of 10°C / min within the measurement temperature range of 30°C to 200°C.

[0165] In the measurement, the temperature is raised to 200° C. once, then lowered to 30° C. at a rate of 10° C. / min, and then raised again.

[0166] During this second heating process, a specific heat change is obtained in the temperature range of 40° C. to 100° C. The intersection point between the line midway between the baselines before and after the specific heat change occurs and the differential heat curve is defined as the glass transition temperature (Tg).

[0167] <Method for identifying the resin type of the outermost layer> The type of resin in the outermost layer is identified using a time-of-flight secondary ion mass spectrometer (TOFSIMS). Measurement equipment: TOFSIMS TRIFTIV (ULVAC-PHI, Inc.) Primary ion species: gold ions (Au + ) Primary ion acceleration voltage: 30 keV Primary ion current value: 2pA Analysis area: 300×300μm 2 Number of pixels: 256 x 256 pixels Analysis time: 3min Repetition frequency: 8.2kHz Charge neutralization: on Secondary ion polarity: Positive Secondary ion mass range (m / z): 0.5 to 1850

[0168] <Method of identifying the structure of the resin type of binder resin> The resin type of the binder resin was determined by nuclear magnetic resonance spectroscopy ( 1 The compound is identified using H-NMR [400 MHz, CDCl3, room temperature (25 °C)] or pyrolysis GCMS.

[0169] (Nuclear magnetic resonance spectroscopy ( 1 H-NMR measurement conditions Measuring device: FT NMR device JNM-EX400 (manufactured by JEOL) Measurement frequency: 400MHz Pulse condition: 5.0μs Frequency range: 10500Hz Number of times accumulated: 64 Solvent: A deuterium solvent capable of dissolving the toner is appropriately used.

[0170] (Measurement conditions for pyrolysis GCMS) Measuring device: Pyrolysis GCMS device Pyrolysis equipment: Curie point pyrolyzer JPS700 (manufactured by Japan Analytical Industry Co., Ltd.) Pyrofoil: F590 (Curie point 590℃) GCMS FocusGC / ISQ (Thermo Fisher Scientific) Carrier gas: He gas (purity 99.99995%) Column: HP-5MS (30 m, inner diameter 0.25 mm, film thickness 0.25 μm) Injection port temperature: 280℃, MS transfer temperature: 280℃, ion current temperature: 250℃ Oven temperature: Start at 50°C, hold for 3 minutes, then increase to 300 at 10°C / min and hold for 30 minutes Helium flow rate: 1.2mL / min constant flow control, split ratio: 20 MS ion source: EI, MS detection range (m / z): 25-800 Library:NIST

[0171] Under the above measurement conditions, 0.5 mg of toner and 5 μL of a methylation reagent (10% tetramethylammonium hydroxide in methanol) are added to the Pyrofoil and analyzed. EXAMPLES

[0172] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is in no way limited thereto. Parts used in the examples are by weight unless otherwise specified.

[0173] (Preparation of Outermost Layer Material: Manufacturing Example of Resin Dispersion 1) In a beaker equipped with a stirrer, 5.0 parts of sodium dodecyl sulfate and 1000.0 parts of ion-exchanged water were added, and stirring was continued until completely dissolved at 25° C. to prepare an aqueous solution. Next, the following materials were mixed to prepare a polymerizable monomer composition. Styrene 70.0 parts Butyl acrylate 13.0 parts 2-Ethylhexyl acrylate 12.0 parts Methyl methacrylate (MMA) 5.0 parts After the temperature of the polymerizable monomer composition was lowered to 15°C, 6.0 parts of tertiary butyl peroxypivalate was mixed as a polymerization initiator and added to the aqueous solution. Then, ultrasonic waves were irradiated for 13 minutes (1 second interval, maintained at 25°C) using a high-output ultrasonic homogenizer (VCX-750) to prepare an emulsion of the polymerizable monomer composition.

[0174] The emulsion was placed in a heated and dried four-neck flask, and nitrogen was bubbled through the emulsion for 30 minutes while stirring at 200 rpm, followed by stirring for 6 hours at 70° C. The emulsion was then air-cooled while still being stirred to terminate the reaction, thereby obtaining a styrene-acrylic resin resin dispersion 1 that would become the outermost layer material.

[0175] Thereafter, the thermoplastic resin dispersion 1 was centrifuged at 16,500 rpm for 1 hour, and the supernatant was removed. Ion-exchanged water was added again, and dispersion and centrifugal separation were repeated three times, and then ion-exchanged water was added to prepare a resin dispersion 1 having a solid content concentration of 20.0 mass%. The volume average diameter of the particles in the resin dispersion 1 was measured to be 25 nm, and the Tg was 69°C.

[0176] (Production Examples of Resin Dispersions 2 to 7) Resin dispersions 2 to 7 were produced in the same manner as in the production example of resin dispersion 1, except that the formulation of the polymerizable monomer composition and the formulation of the resin particle dispersion were changed as shown in Table 1. The volume average diameters and Tg of the particles in resin dispersions 2 to 7 are shown in Table 1.

[0177] [Table 1]

[0178] (Production example of styrene-acrylic resin 1) The following materials were mixed in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen inlet tube, and the temperature was raised and maintained at 180°C while stirring. Styrene 85.0 parts n-Butyl acrylate 7.0 parts Lauryl acrylate 6.0 parts Acrylic acid 2.0 parts 300.0 parts xylene Next, 50.0 parts of a 2.0% xylene solution of t-butyl hydroperoxide was continuously dropped into the system over 4.5 hours, and after cooling, the solvent was separated and removed to synthesize styrene-acrylic resin 1. The weight average molecular weight Mw was 14,500 and Tg was 65°C.

[0179] (Production Examples of Styrene-Acrylic Resins 2 to 9) Styrene-acrylic resins 2 to 9 were produced in the same manner as in the production example of styrene-acrylic resin 1, except that the formulation of the polymerizable monomer composition was changed as shown in Table 2. The weight average molecular weights Mw and Tg of styrene-acrylic resins 2 to 9 are shown in Table 2.

[0180] [Table 2]

[0181] (Production Example of Polyester Resin 1) The following materials were mixed in a reaction vessel equipped with a condenser, stirrer, and nitrogen inlet tube. Polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane 58.0 copies Ethylene glycol 8.0 parts Terephthalic acid 31.0 parts Trimellitic anhydride 3.0 parts Dibutyltin oxide 0.3 parts After the system was purged with nitrogen by reducing the pressure, it was heated to 210°C and reacted for 5 hours while introducing nitrogen and removing the water produced. After that, the temperature was gradually raised to 230°C under reduced pressure while continuing stirring, and the reaction was continued for another 3 hours to synthesize polyester resin 1. The weight average molecular weight Mw was 9,500 and Tg was 68°C.

[0182] (Production Example of Polyester Resin 2) The following materials were mixed in a reaction vessel equipped with a condenser, stirrer, and nitrogen inlet tube. Polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane 42.0 copies Ethylene glycol 22.0 parts Terephthalic acid 31.0 parts Trimellitic anhydride 3.0 parts Dibutyltin oxide 0.3 parts After the system was purged with nitrogen by reducing the pressure, it was heated to 210°C and reacted for 5 hours while introducing nitrogen and removing the water produced. After that, the temperature was gradually raised to 230°C under reduced pressure while continuing stirring, and the reaction was continued for another 3 hours to synthesize polyester resin 2. The weight average molecular weight Mw was 8,200 and Tg was 54°C.

[0183] (Production Example of Toner Base Particle 1) The following materials were thoroughly mixed in an FM mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), and then melt-kneaded in a twin-screw kneader (manufactured by Ikegai Iron Works Co., Ltd.) set at a temperature of 100°C. Styrene-acrylic resin 1 95.0 parts Polyester resin 1 5.0 parts HNP9 (melting point: 76°C, manufactured by Nippon Seiro Co., Ltd.) 5.0 parts ·CIPigment Blue15:3 6.0 copies The obtained kneaded product was cooled and coarsely crushed to 1 mm or less using a hammer mill to obtain a coarsely crushed product.

[0184] Next, the obtained coarsely crushed material was milled using a turbo mill manufactured by Turbo Kogyo Co., Ltd. to obtain finely ground material of about 5 μm, and then the fine and coarse powders were removed using a multi-division classifier utilizing the Coanda effect to obtain toner base particles 1.

[0185] The toner base particles 1 had a weight average particle size (D4) of 6.8 μm and a Tg of 58° C.

[0186] (Production Examples of Toner Base Particles 2 to 14) Toner base particles 2 to 14 were produced in the same manner as in the production example of toner base particles 1, except that the formulation of the toner base particles and the production conditions of the toner base particles were changed as shown in Table 3. The weight average particle diameter (D4) and Tg of toner base particles 2 to 14 are shown in Table 3.

[0187] [Table 3]

[0188] (Production Example of Toner Base Particle Dispersion 1) Into a reaction vessel containing 390.0 parts of ion-exchanged water, 15.0 parts of sodium phosphate (12-hydrate) were added, and the mixture was kept at 65° C. for 1.0 hour while being purged with nitrogen.

[0189] Using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was stirred at 12,000 rpm. While maintaining the stirring, an aqueous calcium chloride solution in which 9.0 parts of calcium chloride (dihydrate) was dissolved in 10.0 parts of ion-exchanged water was added to the reaction vessel all at once to prepare an aqueous medium containing inorganic fine particles as a dispersant. Furthermore, 1.0 mol / L of hydrochloric acid was added to the aqueous medium in the reaction vessel to adjust the pH to 6.0, and aqueous medium 1 was prepared.

[0190] 200.0 parts of toner base particles 1 were added to the aqueous medium 1 and dispersed for 30 minutes while rotating at 7000 rpm using a TK homomixer at a temperature of 40° C. Ion-exchanged water was added to adjust the toner base particle concentration in the dispersion to 20.0%, and toner base particle dispersion 1 was obtained.

[0191] (Production Examples of Toner Base Particle Dispersions 2 to 14, 18, and 19) Toner base particle dispersions 2 to 14, 18, and 19 were produced in the same manner as in the production method for toner base particle dispersion 1, except that the aqueous medium 1 and toner base particles 1 were changed as shown in Table 4.

[0192] (Production Example of Toner Base Particle Dispersion 15) 200.0 parts of toner base particles 13 were added to an aqueous medium 8 containing 400.0 parts of ion-exchanged water and 10.0 parts of resin dispersion 1, and dispersed for 30 minutes at 40° C. with a TK homomixer while rotating at 7000 rpm. Ion-exchanged water was added to adjust the toner base particle concentration in the dispersion to 20.0%, and toner base particle dispersion 15 was obtained.

[0193] (Production Examples of Toner Base Particle Dispersions 16 and 17) Toner base particle dispersions 16 and 17 were produced in the same manner as in the production method of toner base particle dispersion 15, except that the aqueous medium 8 and toner base particles 13 were changed as shown in Table 4.

[0194] [Table 4]

[0195] (Production Example of Toner Particle 1) The following samples were weighed and placed in a reaction vessel, and mixed using a propeller agitator. Toner base particle dispersion liquid 1 500.0 parts ·Resin dispersion 1 10.0 parts Next, the pH of the resulting mixture was adjusted to 7.0 using a 1 mol / L NaOH aqueous solution, and the temperature of the mixture was adjusted to 30°C, after which it was held for 1.0 hour while being mixed at 200 rpm using a propeller impeller.Then, the temperature was raised to 80°C at a rate of 1°C / min while being stirred with a propeller impeller, and held for 2 hours.

[0196] Subsequently, the temperature of the contents was cooled to room temperature (approximately 25°C), the pH was adjusted to 1.5 with 1 mol / L hydrochloric acid, and the contents were stirred for 1.0 hour. After that, the contents were washed with ion-exchanged water and filtered to obtain toner particles 1 having styrene-acrylic resin B in the outermost layer.

[0197] (Production Examples of Toner Particles 2-23, 28-29) In the manufacturing method of toner particle 1, toner particles 2 to 23 and 28 to 29 were manufactured in the same manner as in the manufacturing example of toner particle 1, except that the type of toner base particle dispersion and the type and amount of resin particle dispersion were changed as shown in Table 5.

[0198] (Production Example of Toner Particle 24) (Preparation of Resin Particle Dispersion) Styrene: 84.0 parts Lauryl acrylate: 16.0 parts The above materials were mixed and dissolved, and a solution of 1.0 part of anionic surfactant (Dowfax manufactured by Dow Chemical Co.) dissolved in 60 parts of ion-exchanged water was added, and dispersed and emulsified in a flask to prepare an emulsion of monomers. Next, 2.0 parts of anionic surfactant (Dowfax manufactured by Dow Chemical Co.) was dissolved in 90 parts of ion-exchanged water, to which 2.0 parts of the emulsion of monomers was added, and further, 10 parts of ion-exchanged water in which 1.0 part of ammonium persulfate was dissolved was added.

[0199] The remaining monomer emulsion was then added over a period of 3 hours, the flask was purged with nitrogen, and the solution in the flask was heated to 65°C in an oil bath while stirring, and emulsion polymerization was continued for 5 hours to obtain a resin particle dispersion. Ion-exchanged water was added to the resin particle dispersion to adjust the solid content to 20% by mass.

[0200] (Preparation of Colorant Particle Dispersion) Cyan pigment (Dainichi Seika Chemicals Co., Ltd., Pigment Blue 15:3 (copper phthalocyanine)) 45 parts Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen R) 2 parts 250 parts deionized water The above was mixed, dissolved, and dispersed for about 1 hour using a high-pressure impact disperser Ultimizer (HJP30006, manufactured by Sugino Machine Co., Ltd.) to obtain a cyan colorant particle dispersion. The volume average particle diameter D50v of the particles in this colorant particle dispersion was 150 nm. Ion-exchanged water was then added to adjust the solid content to 20% by mass.

[0201] (Preparation of release agent particle dispersion) Paraffin wax (hydrocarbon wax, Nippon Seiro HNP9, melting temperature 75°C, 2nd endothermic peak temperature of wax (there is only one 2nd endothermic peak) 84°C): 270 parts Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku): 13.5 parts (60% active ingredient by weight, 3% by weight based on release agent) Ion-exchanged water: 21.6 parts The above materials were mixed and the release agent was dissolved in a pressure discharge homogenizer (Gaulin homogenizer manufactured by Gaulin Co., Ltd.) at an internal liquid temperature of 120°C, after which the dispersion was treated at a dispersion pressure of 5 MPa for 120 minutes, then at 40 MPa for 360 minutes, and cooled to obtain a dispersion liquid. Ion-exchanged water was added to adjust the solid content to 20 mass%, and this was used as a release agent particle dispersion liquid.

[0202] (Production of toner particles) ·Resin particle dispersion: 375 parts Colorant particle dispersion: 75 parts Release agent particle dispersion: 15 parts Ion-exchanged water: 750 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 3.2 parts The above material was placed in a 3-liter reaction vessel equipped with a thermometer, pH meter, and stirrer as the material for forming the core portion, and 1.0% nitric acid was added at 25°C to adjust the pH to 3.0. The mixture was then dispersed at 5,000 rpm using a homogenizer (IKA Ultra Turrax T50) while 100 parts of a 2.0% by mass aqueous magnesium chloride solution was added as a flocculant and dispersed for 6 minutes.

[0203] Then, the mixture was heated to 53°C in a heating water bath using a stirring blade while appropriately adjusting the rotation speed so that the mixture was stirred. The volume average particle size of the formed aggregated particles was appropriately confirmed using a Coulter Multisizer III, and when the volume average particle size reached 6.0 μm, the temperature was maintained, and 1:46.5 parts of the resin dispersion liquid was added as a material for forming the shell layer over a period of 5 minutes. The temperature was then raised to 80°C, maintained at 80°C, and when the desired circularity was achieved, the mixture was cooled to 25°C, filtered, solid-liquid separated, and washed with ion-exchanged water. After washing, the mixture was dried using a vacuum dryer to obtain toner particles 24 with a weight average particle size of 6.5 μm.

[0204] (Production Example of Toner Particle 25) 500.0 parts of toner base particle dispersion 16 was added to a reaction vessel, and the temperature was raised to 70°C at a rate of 1°C / min while stirring at 100 rpm. Immediately after the temperature of the reaction vessel reached 55°C during the temperature rise, a 1 mol / L NaOH aqueous solution was added to the reaction vessel to adjust the pH of toner base particle dispersion 16 to 9.0. Thereafter, stirring was continued for 2 hours under conditions of 70°C and 100 rpm.

[0205] Next, the temperature of the contents was cooled to room temperature (25° C.), and then filtration and washing were repeated five times to obtain toner particles 25 having a thermoplastic resin in the outermost layer.

[0206] (Production Example of Toner Particles 26 and 27) Toner particles 26 and 27 were produced in the same manner as in the production example of toner particles 25, except that the type of toner base particle dispersion and the amount of resin particle dispersion were changed as shown in Table 5 in the production method of toner particles 25.

[0207] [Table 5]

[0208] The physical properties of the obtained toner particles 1 to 29 are shown in Table 6. In Table 6, the "existence state" is indicated as ◯ when recesses that satisfy the provisions of the present invention (formulas (2) to (4)) are formed on the surface of the toner particles.

[0209] [Table 6]

[0210] (Toner manufacturing example) (Toner 1) The following external additives were added to 100 parts of toner particles 1, and mixed for 10 minutes at a peripheral speed of 32 m / s in an FM mixer (manufactured by Nippon Coke Corporation). Coarse particles were removed using a mesh with 45 μm openings to obtain toner 1. 1.3 parts hydrophobic silica with a number-average particle size of 12 nm

[0211] (Toner 2-29) Toners 2 to 29 were produced in the same manner as in the production method of toner 1, except that toner particles 1 were replaced with toner particles 2 to 29.

[0212] <Examples 1 to 23 and Comparative Examples 1 to 6> The following evaluations were carried out using the above toners 1 to 29. The evaluation results are shown in Table 7.

[0213] The evaluation methods and evaluation criteria of the present disclosure are described below.

[0214] The image forming device used was a modified version of a commercially available laser printer, LBP-712Ci (Canon). The process speed was changed to 250 mm / sec.

[0215] The process cartridge used was a commercially available toner cartridge 040H (cyan) (manufactured by Canon Inc.) The product toner was removed from the inside of the cartridge, and the inside was cleaned with an air blower, after which 165 g of the above toner was filled into the cartridge.

[0216] In addition, the product toner was removed from each of the yellow, magenta and black stations, and the evaluation was performed by inserting yellow, magenta and black cartridges with the toner remaining amount detection mechanism disabled.

[0217] [Storage test in harsh environments] Approximately 100 g of each of the obtained toners 1 to 29 was placed in a 1000 ml resin cup and left in a low temperature, low humidity environment (15°C, 10% RH) for 24 hours, and then changed to a high temperature, high humidity environment (55°C, 95% RH) over 24 hours. After being left in the high temperature, high humidity environment for 24 hours, the environment was changed again to a low temperature, low humidity environment (15°C, 10% RH) over 24 hours. The above operation was repeated three times, and the toner was taken out. The time chart of the heat cycle is shown in Figure 1.

[0218] To evaluate the image quality after leaving it under the above harsh conditions, the cartridge was left in a low temperature, low humidity environment (15.0°C, 10% RH) for one day, and then fogging was evaluated in the same environment. In a low temperature, low humidity environment, the toner is more easily charged, the charge distribution becomes broader, and fogging is more likely to occur, so the evaluation is more severe.

[0219] Specifically, a solid white image was printed as a test for fog, and its reflectance was measured using a Tokyo Denshoku REFLECTMETER MODEL TC-6DS. On the other hand, the reflectance of the transfer paper (standard paper) before the solid white image was formed was also measured in the same manner. A green filter was used. Fog was calculated from the reflectance before and after the solid white image was printed using the following formula. Fog (reflectance) (%) = Reflectance (%) of standard paper - Reflectance (%) of white image sample

[0220] The evaluation criteria for fogging are as follows: The evaluation results are shown in Table 7.

[0221] (Evaluation criteria for preservation) A: Very good (less than 1.0%) B: Good (1.0% or more, less than 1.5%) C: Normal (1.5% to less than 2.5%) D: Poor (2.5% or more)

[0222] In the present invention, a grade of C or higher is acceptable.

[0223] [Durability evaluation] Using the cartridges after the above-mentioned harsh environment storage stability test, an image output test was conducted in a high temperature and high humidity environment (32.5°C, 85% RH) with a horizontal line pattern with a print rate of 4%, with 2 sheets per job, and the machine stopped between jobs before starting the next job, at 5,000 sheets per day for 4 days, for a total of 20,000 sheets.

[0224] Then, a solid image and a halftone image were output, and the image density and the presence or absence of vertical streaks caused by toner melting to the regulating member, so-called development streaks, were visually confirmed. Finally, 20,000 sheets of images were output. The evaluation results are shown in Table 7.

[0225] (Evaluation criteria for solid images) A: Image density is 1.40 or more B: Image density is 1.30 or more and less than 1.40 C: Image density is 1.20 or more and less than 1.30 D: Image density is less than 1.20

[0226] In the present invention, a grade of C or higher is acceptable.

[0227] (Evaluation criteria for component contamination) A: No development streaks even after 20,000 sheets B: Development streaks occurred between 18,001 and 20,000 sheets. C: Development streaks occurred between 16,001 and 18,000 sheets. D: Development streaks occurred at 16,000 sheets or less

[0228] In the present invention, a grade of C or higher is acceptable.

[0229] [Evaluation of low-temperature fixability] The fixing unit was removed from a modified laser printer LBP-712Ci (Canon). Next, the image receiving paper (Canon Office Planner 64 g / m 2 ) with the filled toner, an unfixed toner image (0.9 mg / cm2) measuring 2.0 cm long x 15.0 cm wide was created. 2 ) was formed at a position 1.0 cm from the upper end in the paper feed direction. Next, the removed fixing unit was modified so that the fixing temperature and process speed could be adjusted, and a fixing test of an unfixed image was carried out using this.

[0230] First, the unfixed image was fixed under normal temperature and humidity conditions (23° C., 60% RH), with a process speed of 250 mm / s, a fixing linear pressure of 27.4 kgf (268.7 N), and an initial temperature of 120° C.

[0231] The voids were evaluated by printing out a solid image and enlarging it ten times with a loupe to check for the presence or absence of defects in the black parts.

[0232] The evaluation criteria are as follows. The evaluation results are shown in Table 7.

[0233] (Evaluation Criteria for Low Temperature Fixability) A: No missing pieces: 0 pieces B: If you look closely, you can see some missing spots: 1 to 3 C: Missing spots are visible but not noticeable: 4 to 6 D: Visible missing spots: 7 or more

[0234] In the present invention, a grade of C or higher is acceptable.

[0235] [Table 7]

Claims

1. A toner having toner particles each having a toner base particle containing a binder resin and an outermost layer present on a surface of the toner base particle, The binder resin contains a styrene-acrylic resin A, The styrene-acrylic resin A has a monomer unit represented by the following formula (1), 【Chemistry 1】 (In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a linear alkyl group having 10 to 15 carbon atoms. the outermost layer present on the surface of the toner base particle contains a styrene-acrylic resin B; A plurality of recesses are formed on the surface of the toner particles, In a cross-sectional analysis of the toner particle observed with a transmission electron microscope, the thickness of the outermost layer is T (nm), When the depressions in the toner particles are measured using a scanning probe microscope from the outermost surface of the outermost layer toward the center of the toner particle, the major axis of the depressions is a (nm), the minor axis of the depressions is b (nm), and the depth of the depressions is d (nm), The surface of the toner particles is 1 μm 2 the number n of the recesses per unit area satisfying the following formulas (2) to (4) satisfies the following formula (5): 50.0≦a≦400.0 Formula (2) 10.0≦b≦100.0 Formula (3) 0.7×T≦d≦1.5×T Formula (4) 0.5≦n≦200 Formula (5)

2. 2. The toner according to claim 1, wherein the styrene-acrylic resin B does not have a monomer unit represented by the formula (1).

3. 3. The toner according to claim 1, wherein the average circularity of the toner particles is 0.920 or more and 0.960 or less.

4. 4. The toner according to claim 1, wherein the thickness T (nm) of the outermost layer is 5.0 nm or more and 100.0 nm or less.

5. 5. The toner according to claim 1, wherein the content of the styrene-acrylic resin A in the toner particles is 30.0% by mass or more and 90.0% by mass or less.

6. 6. The toner according to claim 1, wherein the styrene-acrylic resin A contains the monomer unit represented by the formula (1) in an amount of 1.0% by mass or more and 15.0% by mass or less.

7. The toner according to any one of claims 1 to 6, wherein the styrene-acrylic resin A contains a monomer unit represented by the following formula (6): 【Chemistry 2】 (In formula (6), R 1 represents a hydrogen atom or a methyl group, R 2 represents a linear alkyl group having 12 carbon atoms.

8. The toner according to any one of claims 1 to 7, wherein the styrene-acrylic resin B has a monomer unit represented by the following formula (7): 【Chemistry 3】 (In formula (7), R 1 represents a hydrogen atom or a methyl group, R 2 represents an alkyl group having 1 to 8 carbon atoms.

9. 9. The toner according to claim 8, wherein the styrene-acrylic resin B contains the monomer unit represented by the formula (7) in an amount of 1.0% by mass or more and 40.0% by mass or less.

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