Image forming method and image forming apparatus

Abstract

To provide an image forming method and an image forming apparatus that can prevent set-off and adhesion of sheets.SOLUTION: An image forming method includes a transfer step and an application step. The application step includes applying a fixing solution to a sheet to which toner is transferred in the transfer step. The toner contains a first binder resin and a second binder resin. The first binder resin is a condensate of a first alcohol component containing 1,4-butanediol and a first carboxylic acid component containing a polyvalent carboxylic acid. The molar ratio of 1,4-butanediol in the first alcohol component is 30 mol% or more. The second binder resin is a condensate of a second alcohol component containing a straight-chain diol having 2 to 6 carbon atoms and a second carboxylic acid component containing a polyvalent carboxylic acid. In the toner, the number of domains of the second binder resin having a size exceeding the number-based cumulative 85% particle diameter of the toner is 0.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an image forming method and an image forming apparatus. [Background technology]

[0002] Conventionally, an image forming apparatus includes a photosensitive drum, a transfer device, and an application device (see Patent Document 1 below). The transfer device transfers toner from the photosensitive drum to a sheet. The application device applies a fixing fluid to the toner transferred to the sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-68098 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the image forming apparatus described in the above-mentioned Patent Document 1, if the fixing fluid has low volatility, the toner softened by the fixing fluid is unlikely to harden.

[0005] Therefore, when a second sheet is placed on top of a first sheet on which a toner image has been formed and a fixing fluid has been applied, the softened toner on the first sheet may be transferred to the second sheet. Also, the softened toner may cause the first sheet and the second sheet to stick together.

[0006] Therefore, an object of the present disclosure is to provide an image forming method and an image forming apparatus that can prevent the softened toner of the first sheet from being transferred to the second sheet when a second sheet is placed on top of a first sheet on which a toner image has been formed and a fixing fluid has been applied, and can prevent the first sheet and the second sheet from sticking together due to the softened toner. [Means for solving the problem]

[0007] (1) The image forming method of the present disclosure includes a transfer step and an application step. In the transfer step, the toner on the photosensitive drum is transferred to a sheet. The toner contains a first binder resin and a second binder resin. In the application step, a fixing liquid is applied to the sheet to which the toner has been transferred. The fixing liquid can soften the first binder resin and the second binder resin.

[0008] The first binder resin is a condensation product of a first alcohol component and a first carboxylic acid component. The first alcohol component contains 1,4-butanediol. The first carboxylic acid component contains a polycarboxylic acid. The molar ratio of 1,4-butanediol in the first alcohol component is 30 mol% or more.

[0009] The second binder resin is a condensation product of a second alcohol component and a second carboxylic acid component. The second alcohol component contains a linear diol having 2 to 6 carbon atoms. The second carboxylic acid component contains a polyvalent carboxylic acid.

[0010] In the toner, the number of domains of the second binder resin having a size exceeding the cumulative 85% particle size based on the number of toner particles is zero.

[0011] According to this image forming method, the toner contains, as a first binder resin, a condensate of a first alcohol component containing 30 mol % or more of 1,4-butanediol and a first carboxylic acid component containing a polyvalent carboxylic acid.

[0012] Therefore, when a second sheet is placed on top of a first sheet on which a toner image has been formed and a fixing fluid has been applied, it is possible to prevent the softened toner of the first sheet from being transferred to the second sheet.

[0013] In addition, it is possible to prevent the first sheet and the second sheet from sticking together due to softened toner.

[0014] Furthermore, in the toner, the number of domains of the second binder resin having a size exceeding the cumulative 85% particle size based on the number of toner particles is zero.

[0015] Therefore, when a toner image is formed, the area of ​​the second binder resin in the toner image can be reduced.

[0016] As a result, even if the amount of colorant contained in the second binder resin is lower than the amount of colorant contained in the first binder resin, a decrease in print density can be suppressed.

[0017] (2) The molar ratio of 1,4-butanediol in the first alcohol component may be 65 mol % or less.

[0018] When the molar ratio of 1,4-butanediol in the first alcohol component is 65 mol % or less, the first binder resin can be easily softened by the fixing solution.

[0019] (3) The molar ratio of 1,4-butanediol in the first alcohol component may be 53 mol % or more.

[0020] By having the molar ratio of 1,4-butanediol in the first alcohol component be 53 mol % or more, when a toner image is formed on a first sheet on which a fixing fluid has been applied and a second sheet is then superimposed, it is possible to better prevent the softened toner on the first sheet from being transferred to the second sheet.

[0021] (4) The first binder resin may not have an endothermic peak in differential scanning calorimetry.

[0022] (5) The first binder resin may be amorphous.

[0023] Since the first binder resin is amorphous, the first binder resin can be softened by the fixing fluid, and the toner can be fixed to the sheet.

[0024] (6) The first alcohol component may contain a branched diol.

[0025] (7) The branched diol may be an alkylene oxide adduct of bisphenol A.

[0026] (8) The alkylene oxide adduct of bisphenol A may be at least one of an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A.

[0027] (9) The alkylene oxide adduct of bisphenol A may be an ethylene oxide adduct of bisphenol A.

[0028] (10) The first alcohol component may contain only 1,4-butanediol and an alkylene oxide adduct of bisphenol A. The first carboxylic acid component may contain only a polyvalent carboxylic acid.

[0029] (11) In the first alcohol component, the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol may be 35 / 65 or more and 70 / 30 or less.

[0030] When the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 35 / 65 or more, the first binder resin can be easily softened by the fixing solution.

[0031] When the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 70 / 30 or less, show-through can be further suppressed.

[0032] (12) The molar ratio of the polyvalent carboxylic acid to the total amount of 1,4-butanediol and the alkylene oxide adduct of bisphenol A in the first alcohol component may be 85 / 100 or more and 90 / 100 or less.

[0033] (13) The toner may have an endothermic peak in differential scanning calorimetry.

[0034] (14) The toner may have an endothermic peak temperature of 50° C. or higher and 250° C. or lower.

[0035] By setting the endothermic peak temperature of the toner to 50° C. or more and 250° C. or less, it is possible to further prevent the first sheet and the second sheet from sticking together due to softened toner.

[0036] (15) The toner may have an exothermic peak lower than an endothermic peak in differential scanning calorimetry.

[0037] By having the toner have an endothermic peak and an exothermic peak that is lower in temperature than the endothermic peak, it is possible to further prevent the first sheet and the second sheet from sticking together due to softened toner.

[0038] (16) The toner may have an endothermic peak temperature of 120° C. or more and 200° C. or less. The toner may have an exothermic peak temperature of less than 120° C.

[0039] (17) The second binder resin may have an endothermic peak in differential scanning calorimetry.

[0040] (18) The second binder resin may have an endothermic peak temperature of 50° C. or higher and 250° C. or lower.

[0041] (19) The second binder resin may be contained in an amount of 10% by mass or more and 25% by mass or less based on the total amount of the first binder resin and the second binder resin.

[0042] By containing 10% by mass or more of the second binder resin in the total amount of the first binder resin and the second binder resin, when a toner image is formed and a second sheet is superimposed on the first sheet to which a fixing fluid has been applied, it is possible to further prevent the softened toner of the first sheet from being transferred to the second sheet and the first sheet from sticking to the second sheet due to the softened toner.

[0043] By containing the second binder resin in an amount of 25 mass % or less in the total amount of the first binder resin and the second binder resin, the decrease in print density can be further suppressed.

[0044] (20) The second alcohol component may contain 1,4-butanediol.

[0045] (21) The second alcohol component may contain 1,4-butanediol and an alkylene oxide adduct of bisphenol A.

[0046] (22) The fixing solution may contain an ester-based softening agent.

[0047] (23) In the application step, the ester-based softener may soften the first binder resin, the second binder resin, and the third binder resin.

[0048] (24) The ester-based softener may be a dibasic acid ester.

[0049] (25) The ester-based softener may be a carbonate ester.

[0050] (26) The carbonate ester may be propylene carbonate.

[0051] (27) The ester-based softener may be an aliphatic dicarboxylic acid ester.

[0052] (28) The aliphatic dicarboxylate ester may be at least one selected from the group consisting of diethyl sebacate, diethyl succinate, diethoxyethyl succinate, and dicarbitol succinate.

[0053] (29) The boiling point of the ester-based softener may be 180° C. or higher.

[0054] By setting the boiling point of the ester-based softener to 180° C. or higher, evaporation of the ester-based softener can be suppressed, and therefore generation of an odor due to the ester-based softener can be suppressed.

[0055] (30) The polycarboxylic acid may be an aromatic dicarboxylic acid.

[0056] (31) The aromatic dicarboxylic acid may be terephthalic acid.

[0057] (32) The image forming apparatus according to the present disclosure includes a photosensitive drum, a transfer device, and an application device. The transfer device transfers the toner on the photosensitive drum to a sheet. The application device applies a fixing fluid to the sheet to which the toner has been transferred. Effect of the Invention

[0058] According to the image forming method and image forming apparatus disclosed herein, when a second sheet is placed on top of a first sheet on which a toner image has been formed and a fixing fluid has been applied, it is possible to prevent the softened toner on the first sheet from being transferred to the second sheet and to prevent the first sheet and second sheet from sticking together due to the softened toner. [Brief description of the drawings]

[0059] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus. [Diagram 2]Fig. 2A is an explanatory diagram for explaining a method for measuring the domain size of the second binder resin in the toner, and shows an enlarged image of the toner. Fig. 2B is an explanatory diagram for explaining a method for measuring the domain size of the second binder resin in the toner together with Fig. 2A, and shows one of the domains of the second binder resin shown in Fig. 2A. [Diagram 3] FIG. 3 is a schematic diagram of an offline fixing device used for evaluating fixability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] 1. Overview of image forming apparatus 1 An outline of an image forming apparatus 1 will be described with reference to FIG.

[0061] The image forming apparatus 1 includes a main body housing 2, a sheet storage unit 3, a photosensitive drum 4, a charging device 5, an exposure device 6, a developing device 7, a transfer device 8, and an application device 9.

[0062] 1.1 Main unit 2 The main body housing 2 accommodates a sheet storage section 3, a photosensitive drum 4, a charging device 5, an exposure device 6, a developing device 7, a transfer device 8, and an application device 9.

[0063] 1.2 Sheet storage section 3 The sheet storage unit 3 is capable of storing a sheet S. The sheet S is, for example, a printing paper. The sheet S is transported toward the photosensitive drum 4.

[0064] 1.3 Photosensitive drum 4 The photosensitive drum 4 is rotatable about a drum axis A1. The drum axis A1 extends in a first direction. The photosensitive drum 4 extends in the first direction.

[0065] 1.4 Charging device 5 The charging device 5 charges the surface of the photosensitive drum 4. In this embodiment, the charging device 5 is a charging roller. The charging device 5 may be a scorotron charger.

[0066] 1.5 Exposure Equipment 6 The exposure device 6 exposes the surface of the photosensitive drum 4 that has been charged by the charging device 5. Specifically, the exposure device 6 is a laser scanning unit. The exposure device 6 may be an LED array.

[0067] 1.6 Developing device 7 The developing device 7 supplies toner onto the photosensitive drum 4. More specifically, the developing device 7 supplies toner onto the surface of the photosensitive drum 4 exposed by the exposure device 6. The developing device 7 has a developing housing 71 and a developing roller 72.

[0068] 1.6.1 Developer box 71 The developing housing 71 is capable of containing toner.

[0069] 1.6.2 Developing roller 72 The developing roller 72 can supply toner in the developing housing 71 to the surface of the photosensitive drum 4. In this embodiment, the developing roller 72 contacts the photosensitive drum 4. The developing roller 72 may be spaced apart from the photosensitive drum 4 by a predetermined interval. The developing roller 72 can rotate about a developing axis A2. The developing axis A2 extends in a first direction. The developing roller 72 extends in the first direction.

[0070] 1.7 Transfer device 8 The transfer device 8 transfers the toner on the photosensitive drum 4 to the sheet S. That is, the image forming method includes a transfer process. In the transfer process, the transfer device 8 transfers the toner on the photosensitive drum 4 to the sheet. In this embodiment, the transfer device 8 has a transfer roller 81. The transfer roller 81 contacts the photosensitive drum 4. The transfer roller 81 may be separated from the photosensitive drum 4 at a predetermined interval. The sheet S in the sheet storage unit 4 passes between the photosensitive drum 4 and the transfer roller 81 and is transported to the application device 9. The transfer roller 81 transfers the toner on the photosensitive drum 4 to the sheet S passing between the photosensitive drum 4 and the transfer roller 81. The transfer roller 81 is rotatable about a transfer axis A3. The transfer axis A3 extends in a first direction. The transfer roller 81 extends in the first direction. The transfer device 8 may have a transfer belt.

[0071] 1.8 Application device 9 The application device 9 applies the fixing fluid to the sheet S onto which the toner has been transferred. That is, the image forming method includes an application step. In the application step, the application device 9 applies the fixing fluid to the sheet S onto which the toner has been transferred. The fixing fluid fixes the toner to the sheet S. In this embodiment, the application device 9 sprays the fixing fluid onto the sheet S by electrostatic spraying. The application device 9 may include a fixing roller. The fixing roller applies the fixing fluid to the sheet S. The sheet S onto which the fixing fluid has been applied is discharged onto the top surface of the main body housing 2.

[0072] 2. Toner details Next, the toner will be described in detail.

[0073] The toner contains toner particles and, if necessary, an external additive.

[0074] 2.1 Toner particles The toner particles contain a first binder resin and a second binder resin, that is, the toner contains a first binder resin and a second binder resin.

[0075] The first binder resin and the second binder resin are the base of the toner particles. The first binder resin and the second binder resin bind the components contained in the toner particles. The first binder resin and the second binder resin are softened by the application of the fixing fluid, and then hardened. As a result, the toner is fixed to the sheet S.

[0076] The toner particles contain, as necessary, a colorant, a pigment dispersant, a release agent, a magnetic material and a charge control agent.

[0077] 2.1.1 First binder resin The first binder resin is a polyester resin.

[0078] The first binder resin does not have an endothermic peak in the range of 50° C. to 250° C. in differential scanning calorimetry. That is, the first binder resin is amorphous and does not have a melting point in the range of 50° C. to 250° C. Since the first binder resin is amorphous, the first binder resin can be softened by the fixing fluid, and the toner can be fixed to the sheet S.

[0079] The endothermic peak and melting point are measured by differential scanning calorimetry in accordance with ASTM D3418-99. Specifically, the endothermic peak and melting point are measured by differential scanning calorimetry as described in the Examples below.

[0080] The first binder resin has a softening temperature of, for example, 80° C. or more, preferably 90° C. or more, and for example, 120° C. or less, preferably 110° C. or less.

[0081] The softening temperature is measured by the method described in the examples below.

[0082] More specifically, the first binder resin is a condensate of a first alcohol component and a first carboxylic acid component.

[0083] 2.1.1.1 Primary alcohol component The first alcohol component contains 1,4-butanediol.

[0084] The molar ratio of 1,4-butanediol in the first alcohol component is 30 mol % or more, preferably 53 mol % or more, and for example, 65 mol % or less.

[0085] When the molar ratio of 1,4-butanediol in the first alcohol component is 30 mol % or more, show-through and sticking can be suppressed.

[0086] Note that "show-through" refers to "when a second sheet is placed on top of a first sheet on which a toner image has been formed and a fixing fluid has been applied, the softened toner of the first sheet is shown on the second sheet." "Stick-up" refers to "when a second sheet is placed on top of a first sheet on which a toner image has been formed and a fixing fluid has been applied, the first sheet and the second sheet stick to each other due to the softened toner."

[0087] When the molar ratio of 1,4-butanediol in the first alcohol component is 53 mol % or more, show-through can be further suppressed.

[0088] When the molar ratio of 1,4-butanediol in the first alcohol component is 65 mol% or less, the first binder resin can be easily softened by the fixing solution. When the molar ratio of 1,4-butanediol in the first alcohol component exceeds 65 mol%, the crystallinity of the first binder resin increases, and the first binder resin may become difficult to soften by the fixing solution.

[0089] The first alcohol component may further contain a branched diol.

[0090] Examples of branched diols include branched alkane diols such as 1,2-propanediol, and alkylene oxide adducts of bisphenol A.

[0091] The branched diol is preferably an alkylene oxide adduct of bisphenol A.

[0092] When the first alcohol component contains an alkylene oxide adduct of bisphenol A, the first alcohol component may contain only 1,4-butanediol and an alkylene oxide adduct of bisphenol A.

[0093] Examples of the alkylene oxide adduct of bisphenol A include an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. The alkylene oxide adduct of bisphenol A may be an ethylene oxide adduct of bisphenol A. The alkylene oxide adduct of bisphenol A may be a propylene oxide adduct of bisphenol A. The alkylene oxide adduct of bisphenol A may be a mixture of an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. That is, the alkylene oxide adduct of bisphenol A may be at least one of an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. The number of moles of the alkylene oxide added is, for example, 2 or more and 4 or less.

[0094] When the first alcohol component contains an alkylene oxide adduct of bisphenol A, the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol (alkylene oxide adduct of bisphenol A / 1,4-butanediol) is, for example, 35 / 65 or more, and, for example, 70 / 30 or less, preferably 47 / 53 or less. That is, the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is preferably 35 / 65 or more and 47 / 53 or less.

[0095] When the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is less than 35 / 65, the crystallinity of the first binder resin increases, and the first binder resin may not be easily softened by the fixing solution. When the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 35 / 65 or more, the first binder resin can be easily softened by the fixing solution. When the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 70 / 30 or less, the show-through can be further suppressed. When the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 47 / 53 or less, the show-through can be further suppressed.

[0096] 2.1.1.2 First Carboxylic Acid Component The first carboxylic acid component contains a polycarboxylic acid. Preferably, the first carboxylic acid component contains only a polycarboxylic acid. In other words, the first carboxylic acid component does not contain a monocarboxylic acid.

[0097] Examples of polycarboxylic acids include aromatic dicarboxylic acids such as phthalic acid (1,2-benzenedicarboxylic acid), isophthalic acid (1,3-benzenedicarboxylic acid), terephthalic acid (1,4-benzenedicarboxylic acid), 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, and sebacic acid, and tricarboxylic acids such as trimellitic acid and trimesic acid. The polycarboxylic acid is preferably an aromatic dicarboxylic acid. The aromatic dicarboxylic acid is preferably terephthalic acid.

[0098] The molar ratio of the polycarboxylic acid to the total amount of the primary alcohol components (polycarboxylic acid / total amount of the primary alcohol components) is, for example, 80 / 100 or more and, for example, 90 / 100 or less.

[0099] Specifically, the molar ratio of polycarboxylic acid to the total amount of 1,4-butanediol and alkylene oxide adduct of bisphenol A (polycarboxylic acid / total amount of 1,4-butanediol and alkylene oxide adduct of bisphenol A) is, for example, 80 / 100 or more and, for example, 90 / 100 or less.

[0100] 2.1.1.3 Manufacturing of the first binder resin To produce the first binder resin, the first alcohol component, the polyvalent carboxylic acid, and the esterification catalyst are charged into a reaction vessel and heated, for example, at a temperature of 150° C. or higher and 250° C. or lower for, for example, 5 hours or longer and 10 hours or shorter. This allows the first binder resin to be obtained.

[0101] Specifically, to produce the first binder resin, 1,4-butanediol, an alkylene oxide adduct of bisphenol A, a polycarboxylic acid, and an esterification catalyst are charged into a reaction vessel and heated, for example, at a temperature of 150° C. or higher and 250° C. or lower for, for example, 5 hours or longer and 10 hours or shorter. This allows the first binder resin to be obtained.

[0102] The esterification catalyst may, for example, be tin(II) 2-ethylhexanoate.

[0103] 2.1.2 Second binder resin The second binder resin is a polyester resin.

[0104] The second binder resin is contained in an amount of, for example, 10% by mass or more, for example, 25% by mass or less, in the total amount of the first binder resin and the second binder resin.

[0105] By including 10% by mass or more of the second binder resin in the total amount of the first binder resin and the second binder resin, show-through and sticking can be further suppressed.

[0106] By containing the second binder resin in an amount of 25 mass % or less in the total amount of the first binder resin and the second binder resin, the decrease in print density can be further suppressed.

[0107] The second binder resin has an endothermic peak in differential scanning calorimetry. That is, the second binder resin has crystallinity. The temperature of the endothermic peak of the second binder resin is, for example, 50° C. or more, preferably 120° C. or more, for example, 250° C. or less, preferably 200° C. or less.

[0108] Since the second binder resin has an endothermic peak in differential scanning calorimetry, when the toner contains the second binder resin, the toner has an endothermic peak in differential scanning calorimetry. The temperature of the endothermic peak of the toner is, for example, 50° C. or more, preferably 120° C. or more, for example, 250° C. or less, preferably 200° C. or less.

[0109] Sticking can be further suppressed by having the endothermic peak temperature of the toner be 50° C. or more and 250° C. or less. Also, sticking can be further suppressed by having the endothermic peak temperature of the toner be 120° C. or more and 200° C. or less.

[0110] The endothermic peak is measured by differential scanning calorimetry in accordance with ASTM D3418-99. Specifically, the endothermic peak is measured by differential scanning calorimetry as described in the Examples below.

[0111] The second binder resin may have an exothermic peak at a lower temperature than the endothermic peak in differential scanning calorimetry. The temperature of the exothermic peak of the second binder resin is, for example, lower than 120°C.

[0112] When the toner contains the second binder resin, the toner has an exothermic peak at a lower temperature than the endothermic peak in differential scanning calorimetry because the second binder resin has an exothermic peak in differential scanning calorimetry. When the toner has an exothermic peak, sticking can be further suppressed. When the toner has an exothermic peak in differential scanning calorimetry, the temperature of the exothermic peak is, for example, less than 120°C.

[0113] The exothermic peak is measured by differential scanning calorimetry in accordance with ASTM D3418-99. Specifically, the exothermic peak is measured by differential scanning calorimetry as described in the Examples below.

[0114] The temperature of the endothermic peak can be regarded as the melting point. Therefore, the second binder resin has a melting point. The melting point of the second binder resin is, for example, 50° C. or higher, preferably 120° C. or higher. The melting point of the second binder resin is, for example, 250° C. or lower, preferably 200° C. or lower.

[0115] The softening temperature of the second binder resin is higher than that of the first binder resin. This allows the first binder resin and the second binder resin to be kneaded at a temperature equal to or higher than the softening temperature of the first binder resin and lower than the softening temperature of the second binder resin when producing the toner. The method for producing the toner will be described later. By kneading the first binder resin and the second binder resin at a temperature equal to or higher than the softening temperature of the first binder resin and lower than the softening temperature of the second binder resin, it is possible to suppress compatibility between the first binder resin and the second binder resin. As a result, the obtained toner has a domain of the first binder resin and a domain of the second binder resin. By the toner having a domain of the second binder resin, it is possible to suppress show-through and sticking.

[0116] The difference between the softening temperature of the second binder resin and the softening temperature of the first binder resin is preferably not less than 30° C., and more preferably not less than 50° C. When the difference between the softening temperature of the second binder resin and the softening temperature of the first binder resin is not less than the above lower limit, the first binder resin and the second binder resin can be further prevented from becoming compatible with each other.

[0117] The second binder resin has a softening temperature of, for example, 150° C. or more, preferably 160° C. or more, and for example, 200° C. or less, preferably 190° C. or less.

[0118] More specifically, the second binder resin is a condensate of a second alcohol component and a second carboxylic acid component.

[0119] 2.1.2.1 Secondary alcohol component The second alcohol component contains a linear diol having from 2 to 6 carbon atoms.

[0120] Specific examples of the linear diol having 2 to 6 carbon atoms include linear alkanediols having 2 to 6 carbon atoms, such as ethylene glycol (1,2-ethanediol), 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0121] The second alcohol component preferably contains 1,4-butanediol.

[0122] The second alcohol component may contain a branched diol.

[0123] Examples of the branched diol include the branched diols listed above as the first alcohol component.

[0124] The second alcohol component preferably contains 1,4-butanediol and an alkylene oxide adduct of bisphenol A.

[0125] 2.1.2.2 Second Carboxylic Acid Component The second carboxylic acid component contains a polycarboxylic acid. More specifically, the second carboxylic acid component contains only a polycarboxylic acid. In other words, the second carboxylic acid component does not contain a monocarboxylic acid.

[0126] Examples of the polybasic carboxylic acid include the polybasic carboxylic acids listed above for the first carboxylic acid component.

[0127] 2.1.2.3 Manufacturing of the second binder resin The second binder resin can be produced by the same method as the first binder resin described above.

[0128] 2.1.3 Colorants The colorant imparts a desired color to the toner particles and is dispersed in the first binder resin and the second binder resin.

[0129] Examples of colorants include carbon black, organic pigments, inorganic pigments or metal powders, oil-soluble dyes or disperse dyes, rosin-based dyes, and dyes or pigments processed with higher fatty acids or resins.

[0130] Examples of organic pigments include quinophthalone yellow, Hansa yellow, isoindolinone yellow, benzidine yellow, perinone orange, perinone red, perylene maroon, rhodamine 6G lake, quinacridone red, rose bengal, copper phthalocyanine blue, copper phthalocyanine green, and diketopyrrolopyrrole pigments.

[0131] Examples of inorganic pigments or metal powders include titanium white, titanium yellow, ultramarine blue, cobalt blue, red iron oxide, aluminum powder, and bronze.

[0132] Examples of oil-soluble dyes or disperse dyes include azo dyes, quinophthalone dyes, anthraquinone dyes, xanthene dyes, triphenylmethane dyes, phthalocyanine dyes, indophenol dyes, and indoaniline dyes.

[0133] Examples of rosin-based dyes include rosin, rosin-modified phenol, and rosin-modified maleic acid resin.

[0134] Depending on the desired color, the toner particles may contain only one colorant, multiple colorants, or no colorants.

[0135] The mixing ratio of the colorant relative to 100 parts by mass of the total amount of the first binder resin and the second binder resin is, for example, 2 parts by mass or more, preferably 5 parts by mass or more, and for example, 20 parts by mass or less, preferably 15 parts by mass or less.

[0136] The amount of colorant contained in the domain of the second binder resin is less than the amount of colorant contained in the domain of the first binder resin. This is believed to be because, when producing the toner, the first binder resin, the second binder resin, and the colorant are kneaded at a temperature equal to or higher than the softening temperature of the first binder resin and lower than the softening temperature of the second binder resin, so that the colorant mixes with the softened first binder resin, but does not mix with the unsoftened second binder resin.

[0137] 2.1.4 Pigment dispersants The pigment dispersant improves the dispersibility of the colorant.

[0138] The mixing ratio of the pigment dispersant relative to 100 parts by mass of the colorant is, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass or less.

[0139] 2.1.5 Charge control agents The charge control agent imparts chargeability to the toner particles, which may be either positive or negative.

[0140] Examples of the charge control agent include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based surfactants, salicylic acid metal salts, metal salts of salicylic acid derivatives, copper phthalocyanine, perylene, quinacridone, azo pigments, and polymeric compounds having functional groups (sulfonic acid groups, carboxyl groups, quaternary ammonium groups, etc.).

[0141] The mixing ratio of the charge control agent is, relative to 100 parts by mass of the total amount of the first binder resin, the second binder resin, and the third binder resin, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, and for example, 20 parts by mass or less, preferably 10 parts by mass or less.

[0142] 2.1.6 Release agents Examples of the release agent include polyolefin waxes, long-chain hydrocarbon waxes, and ester waxes.

[0143] The mixing ratio of the release agent relative to 100 parts by mass of the total amount of the first binder resin, the second binder resin, and the third binder resin is, for example, 0 parts by mass or more, preferably 1 part by mass or more, and for example, 20 parts by mass or less, preferably 10 parts by mass or less.

[0144] 2.1.7 Magnetic materials Examples of magnetic materials include magnetite, γ-hematite, and various types of ferrite.

[0145] The mixing ratio of the magnetic material is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, and for example, 500 parts by mass or less, preferably 150 parts by mass or less, relative to 100 parts by mass of the total amount of the first binder resin, the second binder resin, and the third binder resin. The magnetic material can also be used as the above-mentioned colorant.

[0146] 2.2 External additives The external additive adjusts the chargeability, fluidity, and storage stability of the toner particles. Examples of the external additive include inorganic particles and synthetic resin particles.

[0147] Examples of inorganic particles include silica, aluminum oxide, titanium oxide, silicon-aluminum co-oxide, silicon-titanium co-oxide, and hydrophobic products thereof. For example, hydrophobic products of silica can be obtained by treating fine powder of silica with silicone oil or a silane coupling agent such as dichlorodimethylsilane, hexamethyldisilazane, or tetramethyldisilazane.

[0148] Examples of synthetic resin particles include methacrylic acid ester polymer particles, acrylic acid ester polymer particles, styrene-methacrylic acid ester copolymer particles, styrene-acrylic acid ester copolymer particles, and core-shell particles having a styrene polymer core and a methacrylic acid ester polymer shell.

[0149] The particle size of the external additive is smaller than that of the toner particles, and is, for example, 2 μm or less, preferably 0.1 μm or less, and more preferably 0.03 μm or less.

[0150] The mixing ratio of the external additive is, for example, 0.1 parts by mass or more, and for example, 10 parts by mass or less, with respect to 100 parts by mass of the toner particles.

[0151] 2.3 Toner manufacturing method Toner production begins with the production of toner particles, which can be produced by a kneading and pulverizing method, a suspension polymerization method, an emulsion polymerization and aggregation method, an emulsion and astringency method, or an injection granulation method.

[0152] To produce toner particles, a first binder resin, a second binder resin, a charge control agent, and a colorant are mixed, and the resulting mixture is melted and kneaded in a twin-screw extruder at a temperature equal to or higher than the softening temperature of the first binder resin and lower than the softening temperature of the second binder resin.

[0153] The second binder resin may be pulverized in advance before being mixed with the first binder resin, the charge control agent, and the colorant. The volume median particle diameter (D 50 ) is, for example, 10 μm or less, preferably 5 μm or less, and for example, 1 μm or more.

[0154] The resulting kneaded product is then cooled and pulverized to obtain toner particles.

[0155] Next, to produce the toner, an external additive is added to the obtained toner particles and mixed. In this way, the toner can be obtained. The particle size of the toner is the volume median particle size (D 50 ) and is, for example, 3 μm or more, preferably 5 μm or more, and for example, 12 μm or less, preferably 9 μm or less.

[0156] In addition, the cumulative 85% particle diameter (D 85 ) is, for example, 3 μm or more, preferably 5 μm or more, and for example, 12 μm or less, preferably 9 μm or less.

[0157] Volume median particle size (D 50 ), and the cumulative 85% particle size based on the number (D 85) is measured by the method described in the Examples below.

[0158] 3. Domain size of the second binder resin in the toner Next, a method for measuring the domain size of the second binder resin in the toner will be described with reference to FIGS. 2A and 2B.

[0159] In this embodiment, the toner contains a mixture of domains of the first binder resin and domains of the second binder resin.

[0160] Note that "domains of the first binder resin and domains of the second binder resin are mixed in the toner" includes a case where toner particles having domains of the first binder resin and domains of the second binder resin are present in the toner, and a case where toner particles made of the first binder resin and toner particles made of the second binder resin are mixed in the toner, and the toner particles made of the first binder resin constitute the domains of the first binder resin in the toner, and the toner particles made of the second binder resin constitute the domains of the second binder resin in the toner.

[0161] In this embodiment, the amount of colorant contained in the second binder resin is lower than the amount of colorant contained in the first binder resin.

[0162] Therefore, if the domain size of the second binder resin is large, when a toner image is formed, the area of ​​the second binder resin in the toner image becomes large.

[0163] As a result, if the domain size of the second binder resin is large, the print density will be low when a toner image is formed.

[0164] The domain size of the second binder resin is measured by image analysis of the cross section of a toner pellet, which is a compression molded product of the toner. The toner pellet is obtained by pressing 2 g of the toner at 200 MPa for 10 seconds. The toner pellet has a cylindrical shape with a diameter of 25 mm.

[0165] As shown in FIG. 2A, in the image of the cross section of the toner pellet, a plurality of domains B2 of the second binder resin are present in a domain B1 of the first binder resin.

[0166] In the image analysis, first, a horizontal line passing through the center of gravity C of the domain B2 of the second binder resin obtained by binarization is defined, and the diameter of the domain B2 in a direction rotated a predetermined angle from the horizontal line about the center of gravity C is measured.

[0167] 2B, multiple diameters are measured for one domain B2, such as the diameter of domain B2 in the direction along the horizontal line being D(0), the diameter of domain B2 in the direction rotated by θ1° from the horizontal line about the center of gravity C being D(θ1), the diameter of domain B2 in the direction rotated by θ2° from the horizontal line about the center of gravity C being D(θ2), the diameter of domain B2 in the direction rotated by θ3° from the horizontal line about the center of gravity C being D(θ3), and the diameter of domain B2 in the direction rotated by θ4° from the horizontal line about the center of gravity C being D(θ4). The predetermined angle is set at 1° intervals from 0° to 180°.

[0168] The sum of the obtained diameters is divided by 180 to obtain an average value, which is defined as the size of domain B2.

[0169] In the image analysis, the size of each of the multiple domains B2 is measured. The size of the domains B2 to be measured is 0.5 μm or more and 50 μm or less. The number of domains B2 to be measured is 1000 or more.

[0170] Next, the image is analyzed to determine the number-based size distribution of multiple B2 domains.

[0171] Based on the measured size distribution, the number of domains B2 of the second binder resin in the toner having a size exceeding the cumulative 85% particle diameter based on the number of toner particles is 0. In other words, the percentage of the number of domains B2 of the second binder resin having a size exceeding the cumulative 85% particle diameter based on the number of toner particles to the total number of domains B2 of the second binder resin in the toner is 0%. In further other words, the size of the domains B2 of the second binder resin in the toner is equal to or smaller than the cumulative 85% particle diameter based on the number of toner particles.

[0172] Therefore, when a toner image is formed, the area of ​​the second binder resin in the toner image can be prevented from increasing.

[0173] As a result, the decrease in print density can be suppressed.

[0174] 4. Fixing solution The fixing solution can soften the first binder resin and the second binder resin. The fixing solution contains an ester-based softener. The fixing solution may further contain a diluent and a surfactant.

[0175] 4.1 Ester-based softeners The ester-based softener softens the first binder resin and the second binder resin in the above-mentioned application process. This allows the fixing fluid to soften the first binder resin and the second binder resin in the above-mentioned application process. The boiling point of the ester-based softener at 1 atmospheric pressure is, for example, 180° C. or higher, preferably 250° C. or higher, and is, for example, 400° C. or lower. That is, the ester-based softener is unlikely to evaporate in the environment in which the above-mentioned image forming apparatus 1 is used. Therefore, it is possible to suppress the generation of an odor from the ester-based softener.

[0176] Examples of the ester-based softening agent include aliphatic carboxylates and carbonates.

[0177] Examples of the aliphatic carboxylate ester include an aliphatic monocarboxylate ester represented by the following chemical formula (1). Examples of the aliphatic carboxylate ester include an aliphatic dicarboxylate ester such as an aliphatic dicarboxylate dialkyl represented by the following chemical formula (2) and an aliphatic dicarboxylate dialkoxyalkyl represented by the following chemical formula (3).

[0178] Chemical formula (1): R1-COO-R2 (wherein R1 and R2 are linear or branched alkyl groups. R1 and R2 may be different from each other or may be the same. It is preferable that R1 is a linear or branched alkyl group having 9 to 15 carbon atoms, and R2 is a linear or branched alkyl group having 1 to 4 carbon atoms.) Chemical formula (2): R3(-COO-R4)2 (wherein R3 is a linear or branched alkylene group. R4 is a linear or branched alkyl group. The two R4s may be different from each other or may be the same. It is preferable that R3 is a linear or branched alkylene group having 2 to 10 carbon atoms, and R4 is a linear or branched alkyl group having 1 to 8 carbon atoms.) Chemical formula (3):R5[-COO-(R6-O) n -R7]2 (wherein R5 or R6 is a linear or branched alkylene group. R7 is a linear or branched alkyl group. It is preferable that R5 is a linear or branched alkylene group having 2 to 10 carbon atoms, R6 is a linear or branched alkylene group having 2 to 4 carbon atoms, and R7 is a linear or branched alkyl group having 1 to 4 carbon atoms. n is an integer of 1 or more. n is, for example, 3 or less.) Examples of the aliphatic monocarboxylic acid ester include ethyl decanoate (boiling point 243° C.), ethyl laurate (boiling point 275° C.), and ethyl palmitate (boiling point 330° C.).

[0179] Examples of the aliphatic dialkyl dicarboxylates include diethyl succinate (boiling point 196°C), diethyl adipate (boiling point 251°C), diisobutyl adipate (boiling point 293°C), dioctyl adipate (boiling point 335°C), diethyl sebacate (boiling point 309°C), dibutyl sebacate (boiling point 345°C), dioctyl sebacate (boiling point 377°C), and diethyl dodecanedioate (boiling point 200°C or higher).

[0180] Examples of dialkoxyalkyl aliphatic dicarboxylates include diethoxyethyl succinate (boiling point 200°C or higher), dibutoxyethyl succinate (boiling point 200°C or higher), dicarbitol succinate (also known as bis(ethoxydiglycol) succinate, boiling point 200°C or higher), and diethoxyethyl adipate (boiling point 200°C or higher).

[0181] Examples of carbonate esters include ethylene carbonate (boiling point 261° C.) and propylene carbonate (boiling point 242° C.).

[0182] The ester-based softener is preferably a dibasic acid ester such as an aliphatic dicarboxylate or a carbonate. The aliphatic dicarboxylate is preferably at least one selected from the group consisting of diethyl sebacate, diethyl succinate, diethoxyethyl succinate, and dicarbitol succinate. The carbonate is preferably propylene carbonate.

[0183] The blending ratio of the ester-based softener in the fixing liquid is, for example, 5% by mass or more, and for example, 100% by mass or less.

[0184] 4.2 Diluents The diluent is a solvent for diluting the ester-based softener. The ester-based softener may be diluted by dispersing it in the diluent. The ester-based softener may also be diluted by dispersing the diluent in the ester-based softener. The ester-based softener may also be diluted by dissolving it in the diluent.

[0185] Examples of diluents include water, monohydric or polyhydric alcohol solvents, n-alkanes, isoparaffin, silicone oil, etc. Examples of monohydric or polyhydric alcohol solvents include ethanol, propylene glycol, glycerin, etc.

[0186] 4.3 Surfactants The surfactant is added to the fixing solution in order to disperse the ester-based softener in the diluent, or the surfactant is added to the fixing solution in order to disperse the diluent in the ester softener.

[0187] Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonates and aliphatic sulfonates, cationic surfactants such as aliphatic amine salts and aliphatic quaternary ammonium salts, and nonionic surfactants such as polyoxyethylene alkyl ethers.

[0188] The surfactant is contained in the fixing liquid in an amount of, for example, 0.1% by mass or more, and for example, 30% by mass or less.

[0189] 5. Effects (1) According to the image forming apparatus 1 and the image forming method, the toner contains, as a first binder resin, a condensate of a first alcohol component containing 30 mol % or more of 1,4-butanediol and a first carboxylic acid component containing a polycarboxylic acid.

[0190] Therefore, show-through and sticking can be suppressed.

[0191] In this embodiment, the amount of colorant contained in the second binder resin is lower than the amount of colorant contained in the first binder resin.

[0192] Therefore, when a toner image is formed, if the area of ​​the second binder resin in the toner image is large, the print density will be low.

[0193] In this regard, the number of domains of the second binder resin having a size exceeding the cumulative 85% particle size based on the number of toner particles in the toner is zero.

[0194] Therefore, when a toner image is formed, the area of ​​the second binder resin in the toner image can be prevented from increasing.

[0195] As a result, the decrease in print density can be suppressed.

[0196] (2) According to the image forming apparatus 1 and the image forming method, the molar ratio of 1,4-butanediol in the first alcohol component is 65 mol % or less.

[0197] Therefore, the first binder resin can be easily softened by the fixing liquid.

[0198] (3) According to the image forming apparatus 1 and the image forming method, the molar ratio of 1,4-butanediol in the first alcohol component is 53 mol % or more.

[0199] Therefore, show-through can be further suppressed.

[0200] (4) According to the image forming apparatus 1 and the image forming method, the first binder resin is amorphous.

[0201] Therefore, the first binder resin can be softened by the fixing fluid, and the toner can be fixed onto the sheet S.

[0202] (5) According to the image forming apparatus and the image forming method, the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 35 / 65 or more.

[0203] Therefore, the first binder resin can be easily softened by the fixing liquid.

[0204] (6) According to the image forming apparatus and the image forming method, the molar ratio of the alkylene oxide adduct of bisphenol A to 1,4-butanediol is 70 / 30 or less.

[0205] Therefore, show-through can be further suppressed.

[0206] (7) According to the image forming apparatus and the image forming method, the toner contains a second binder resin, and the toner has an endothermic peak temperature of 50° C. or more and 250° C. or less.

[0207] Therefore, sticking can be further suppressed.

[0208] (8) According to the image forming apparatus 1 and the image forming method, the toner has an endothermic peak and an exothermic peak that is lower in temperature than the endothermic peak.

[0209] Therefore, sticking can be further suppressed.

[0210] (9) According to the image forming apparatus 1 and the image forming method, the second binder resin is contained in an amount of 10% by mass or more in the total amount of the first binder resin and the second binder resin.

[0211] Therefore, show-through and sticking can be further suppressed.

[0212] (10) According to the image forming apparatus 1 and the image forming method, the second binder resin is contained in an amount of 25 mass % or less in the total amount of the first binder resin and the second binder resin.

[0213] Therefore, the decrease in print density can be further suppressed.

[0214] (11) According to the image forming apparatus and the image forming method, the boiling point of the ester-based softener is 180° C. or higher.

[0215] Therefore, evaporation of the ester-based softener can be suppressed.

[0216] As a result, the generation of odor from the ester-based softener can be suppressed.

[0217] 6. Variations (1) The developing method in the above embodiment is a one-component developing method using only magnetic or non-magnetic toner, but the present invention is not limited to the above embodiment.

[0218] The developing method may be, for example, a two-component developing method in which a toner and a carrier are mixed. In the case of a two-component developer, the carrier may be, for example, an alloy of a metal such as iron, ferrite, or magnetite with a metal such as aluminum or lead.

[0219] The carrier particle size is, for example, 4 μm or more, preferably 20 μm or more, and for example, 200 μm or less, preferably 150 μm or less.

[0220] The mixing ratio of the toner relative to 100 parts by mass of the carrier is, for example, 1 part by mass or more, or preferably 2 parts by mass, and for example, 200 parts by mass or less, or preferably 50 parts by mass or less.

[0221] The carrier may be a resin-coated carrier or a dispersion-type carrier in which magnetic powder is dispersed in a binder resin.

[0222] (2) The developing device 7 may be configured as one process unit together with the photosensitive drum 4 and the charging device 5. The process unit may be attachable to the main body housing 2.

[0223] (3) The developing device 7 may be a developing cartridge that can be attached to a drum unit having the photosensitive drum 4 and the charging device 5. The drum unit may be attachable to the main body 2.

[0224] (4) The developing device 7 may include a developing unit having a developing roller 72 and a toner cartridge that can be attached to the developing unit. In this case, the toner cartridge can contain toner. The developing unit may be provided in the drum unit. The developing unit may be attachable to the drum unit. EXAMPLES

[0225] The present invention will now be described with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0226] 1. Production of the first binder resin and the second binder resin A linear diol, a branched diol, and a polycarboxylic acid other than trimellitic anhydride were charged in a reaction vessel (a 5 L four-neck flask) in the molar ratios shown in Table 1. The reaction vessel was equipped with a thermometer, a stainless steel stirring rod, a rectification column through which hot water was passed, a downflow condenser, and a nitrogen inlet tube.

[0227] Next, tin(II) 2-ethylhexanoate was added as an esterification catalyst, and the mixture was heated to 180° C. in a mantle heater under a nitrogen atmosphere, and then heated to 230° C. over 8 hours.

[0228] Thereafter, trimellitic anhydride was added to the reaction vessel in the molar ratio shown in Table 1 as necessary, and the reaction vessel was heated at 220° C. while reducing the pressure inside the reaction vessel to 8.0 kPa until the softening temperature of the reaction product reached the softening temperature shown in Table 1.

[0229] The softening temperature was measured using a flow tester "CFT-500D" (Shimadzu Corporation). Specifically, about 1 g of sample was heated from 50°C to 200°C at a temperature increase rate of 6°C / min, while applying a load of 1.96 MPa with a plunger, and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The plunger descent amount of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening temperature.

[0230] By the above reaction, a first binder resin and a second binder resin shown in Table 1 were obtained. Table 1 shows the glass transition temperatures and endothermic peak temperatures of the obtained binder resins.

[0231] The glass transition temperature and the endothermic peak temperature were measured by differential scanning calorimetry.

[0232] Differential scanning calorimetry was performed using a differential scanning calorimeter "DSC Q20" (manufactured by TA Instruments Japan) in accordance with ASTM D3418-99. The melting temperatures of indium and zinc were used to correct the temperature of the detector. The heat of fusion of indium was used to correct the amount of heat.

[0233] Specifically, 5 mg of the obtained binder resin was placed in an aluminum pan, and the temperature was increased from -10°C to 250°C at a rate of 10°C / min using an empty aluminum pan as a reference (first temperature increase).

[0234] Next, after holding at 250°C for 2 minutes, the temperature was lowered to -10°C at a rate of -20°C / min (first temperature drop). Next, after keeping at -10°C for 5 minutes, the temperature was increased again from -10°C to 250°C at a rate of 10°C / min (second temperature increase).

[0235] The glass transition temperature was determined from the DSC curve of the baseline shift due to the specific heat change obtained in the second heating. Specifically, the intersection of the line midway between the baselines before and after the specific heat change and the DSC curve was taken as the glass transition temperature Tg.

[0236] The endothermic peak temperature was determined from the apex temperature of the endothermic peak in the DSC curve obtained during the first heating run.

[0237] [Table 1]

[0238] 2. Toner manufacturing The obtained second binder resin was pulverized to about 1 mm using a hammer mill, and the pulverized product was further pulverized using an air jet pulverizer. The volume median particle size (D 50 ) was 4.5 μm. The coefficient of variation (CV) of the ground product of the obtained second binder resin was 32%. In addition, in Comparative Example 1, the obtained second binder resin was not ground.

[0239] Next, the first binder resin and the second binder resin (in Examples 1 to 4, the pulverized second binder resin) in the amounts shown in Table 2, 3 parts by mass of Bontron N-04 (charge control agent, manufactured by Orient Chemical Industry Co., Ltd.), 7 parts by mass of FCA-F201-PS (charge control agent, manufactured by Fujikura Chemical Industries Co., Ltd.), and 6 parts by mass of Regal 330R (colorant, carbon black, manufactured by Cabot Corporation) were mixed using a Henschel mixer.

[0240] Next, the obtained mixture was melted and kneaded in a twin-screw extruder at a temperature equal to or higher than the softening temperature of the first binder resin and lower than the softening temperature of the second binder resin.

[0241] Next, the obtained kneaded product was cooled and pulverized to about 1 mm using a hammer mill.

[0242] Next, the obtained pulverized material was further pulverized by an air jet type pulverizer.

[0243] Next, the resulting pulverized material was classified to determine the volume median particle size (D 50 The toner particles obtained had a cumulative 85% particle diameter (D 85 ) are listed in Table 2.

[0244] The volume median particle size (D 50 ), and the cumulative 85% particle size based on the number (D 85) was measured using a Coulter Multisizer II (manufactured by Beckman Coulter) with an aperture diameter of 100 μm. The analysis software used was Coulter Multisizer Accucomp version 1.19 (manufactured by Beckman Coulter). In detail, a solution in which 5% by mass of Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB (Griffin): 13.6) was dissolved in an electrolyte (Isoton II, manufactured by Beckman Coulter) was used as the dispersion liquid. 10 mg of toner particles were added to 5 ml of the dispersion liquid, and the toner particles were dispersed for 1 minute using an ultrasonic disperser US-1 (manufactured by SND Corporation, output: 80 W). Next, 25 ml of electrolyte was added, and the dispersion was further dispersed for 1 minute using an ultrasonic disperser to prepare a sample dispersion liquid. Next, the sample dispersion liquid was added to 100 ml of electrolyte liquid so that the particle size of 30,000 particles could be measured in 20 seconds, and 30,000 particles were measured, and the volume median particle size (D 50 ), and the cumulative 85% particle size based on the number (D 85 ) was sought.

[0245] Next, 0.5 parts by mass of NAX-50 (external additive, hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd.) and 0.5 parts by mass of RX-300 (external additive, hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd.) were added to 100 parts by mass of the obtained toner particles and mixed using a Henschel mixer.

[0246] In this way, toners were obtained. All of the obtained toners had exothermic peaks at around 100° C. All of the obtained toners had endothermic peaks at around 180° C.

[0247] The exothermic peak temperature and the endothermic peak temperature were measured by the above-mentioned differential scanning calorimetry. The exothermic peak temperature was determined from the apex temperature of the exothermic peak in the DSC curve obtained during the first heating run. The endothermic peak temperature was determined from the apex temperature of the endothermic peak in the DSC curve obtained during the first heating run.

[0248] [Table 2]

[0249] 3. Image analysis of the second binder resin in the toner (1) Preparation of toner pellets 2 g of the toner was placed in a tablet press die with an inner diameter of 25 mm so that the surface was uniform. Next, a pressure of 200 MPa (measured by the scale of a Bourdon tube load gauge) was applied to the toner in the die for 10 seconds, yielding a toner pellet with a diameter of 25 mm and a thickness of approximately 2 mm.

[0250] (2) Image analysis The obtained toner pellets were cut using a microtome (ultramicrotome: "ULTRACUT UCT" manufactured by LEICA, ultrasonic diamond knife (blade angle: 35°): manufactured by DiATOME), and etched for 4 minutes using an ion etching device ("PIB-20" manufactured by Vacuum Device Co., Ltd.) under conditions of a vacuum degree of 80 Pa and an ion current value of 40 mA, to prepare a cross section of the toner pellet.

[0251] Next, the cross section of the obtained toner pellet was observed under the following conditions using a microscope (DSX510, manufactured by Olympus Corporation).

[0252] <Observation conditions> Observation mode: BF mode (incident light mode) Light output: 6069 Exposure time: 100ms ISO sensitivity: 800 Lens used: MPLAPON50X Under the above observation conditions, after adjusting the white balance in Auto, images were taken at 4160x magnification in extended focus mode.

[0253] Next, the image was analyzed using image analysis software (OLYMPUS STREAM) under the following analysis conditions, and 1000 or more particles with a size of 0.5 μm or more and less than 50 μm were observed to determine the size of the domain of the second binder resin. In addition, the domains were classified into the following five classes, and the number distribution of the domains of the second binder resin was determined.

[0254] The percentage of the number of domains of the second binder resin having a size exceeding the cumulative 85% particle diameter based on the number of toner particles relative to the total number of domains of the second binder resin in the toner is shown in Table 2. In Examples 1 to 4 and Comparative Example 2, the percentage of the number of domains of the second binder resin having a size exceeding the cumulative 85% particle diameter based on the number of toner particles relative to the total number of domains of the second binder resin in the toner was 0%. That is, in Examples 1 to 4 and Comparative Example 2, the number of domains B2 of the second binder resin having a size exceeding the cumulative 85% particle diameter based on the number of toner particles in the toner was 0.

[0255] <Analysis conditions> Counting and measuring modes Convert to Grayscale Threshold: 184 (adjusted to fit actual image) Detection range: Frame Detection conditions: Connect adjacent pixels, exclude pixels less than 100 pixels, exclude particles adjacent to the frame, fill holes Measurement items: number, diameter (average) Classification: Classified into five classes: 0.5 μm or more and less than 1.3 μm, 1.3 μm or more and less than 3.2 μm, 3.2 μm or more and less than 8.0 μm, 8.0 μm or more and less than 20 μm, and 20.0 μm or more and less than 50 μm.

[0256] 4. Evaluation (1) Show-through and sticking The toner thus obtained was filled into a developing cartridge, and the toner adhesion amount was measured using an image forming apparatus "HL-L2360D" (manufactured by Brother Industries) with the heat fixing unit removed, at a level of 5 g / m 2 A toner image having the following characteristics was formed on the surface of the first sheet. Note that since the heat fixing device was removed, the toner image was not fixed to the first sheet.

[0257] Next, the fixing solution shown in Table 2 was sprayed onto the toner image T at a spray amount of 0.1 g per A4 size using an offline fixing unit equipped with the sprayer 100 shown in Fig. 3. The sprayer 100 is an airbrush that sprays the fixing solution using compressed air.

[0258] Thirty minutes after spraying the fixing fluid onto the toner image T, a second sheet is placed on the surface of the first sheet on which the toner image T is formed, and a fixing fluid of 150 g / cm is applied to the part on which the toner image T is formed. 2 A weight was placed on the sample so that a pressure of 100 g was applied, and the sample was then placed in a thermo-hygrostat chamber at a temperature of 25°C and a humidity of 30% for 24 hours.

[0259] In this way, an evaluation sample was obtained.

[0260] The second sheet of the obtained evaluation sample was peeled off from the first sheet, and the show-through and sticking were evaluated according to the following evaluation criteria. The results are shown in Table 2. Note that A to C are levels that are acceptable for practical use.

[0261] <Evaluation criteria for show-through> A: There is almost no show-through.

[0262] B: There is some show-through.

[0263] C: Show-through is observed, but the print is acceptable.

[0264] D: There is a lot of show-through and it is not acceptable as a printed matter.

[0265] <Evaluation criteria for sticking> A: It doesn't feel sticky.

[0266] B: I barely feel any sticking.

[0267] C: There is some sticking and there is a slight peeling sound.

[0268] D: Most of the surface is stuck together and there is a sound of it peeling off.

[0269] (2)Print density The toner thus obtained was filled into a developing cartridge, and the toner adhesion amount was measured using an image forming apparatus "HL-L2360D" (manufactured by Brother Industries) with the heat fixing unit removed, at a level of 5 g / m 2A toner image (10 mm×10 mm, square) was formed on each of the three sheets of printing paper. Note that since the heat fixing device was removed, the toner image was not fixed to the printing paper.

[0270] Next, the fixing solution shown in Table 2 was sprayed onto the toner images T on each of the three sheets of printing paper at a spray amount of 0.1 g per A4 size using an offline fixing unit equipped with the sprayer 100 shown in Fig. 2. The sprayer 100 is an airbrush that sprays the fixing solution using compressed air.

[0271] Next, the reflection density OD1 of the toner image T was measured by a spectrophotometer. The spectrophotometer used was a Spectroeye (manufactured by X-Rite Corporation). The average reflection density OD1 of each of the three sheets of printing paper is shown as the print density in Table 2. The larger the value, the higher the print density.

[0272] (3) Development durability The toner obtained was filled into a developing cartridge, and a square image of 10 mm x 10 mm was printed in the center of a page on a total of 5000 pages using an image forming apparatus "HL-L6400DW" (manufactured by Brother Industries). The print area ratio per page was 1%. The printing conditions were a development bias of 400 V, a temperature of 25°C, and a relative humidity of 10%. Next, the reflection density OD1 before printing and the reflection density OD2 after printing were measured using a spectrophotometer (product name: Spectroeye, manufactured by X-Rite). The percentage of the reflection density OD2 after printing relative to the reflection density OD1 before printing (density maintenance rate) was calculated using the following formula, and the development durability was evaluated from the obtained concentration maintenance rate according to the following evaluation criteria.

[0273] <expression> Density maintenance rate [%]=Reflection density OD2 / Reflection density OD1×100 <Evaluation criteria> ◎: 95% or more ○: 90% or more, less than 95% ×: Less than 90% [Explanation of symbols]

[0274] 1. Image forming device 4 Photosensitive drum 8. Transcription device 9. Application Device S Seat

Claims

1. a transfer step of transferring the toner on the photosensitive drum, the toner including a first binder resin and a second binder resin, to a sheet; applying a fixing liquid capable of softening the first binder resin and the second binder resin to the sheet onto which the toner has been transferred; Including, the first binder resin is a condensate of a first alcohol component containing 1,4-butanediol and a first carboxylic acid component containing a polyvalent carboxylic acid, and a molar ratio of the 1,4-butanediol in the first alcohol component is 30 mol% or more; the second binder resin is a condensate of a second alcohol component containing a linear diol having 2 to 6 carbon atoms and a second carboxylic acid component containing a polyvalent carboxylic acid, the number of domains of the second binder resin having a size exceeding a cumulative 85% particle size based on the number of the toner particles is 0 in the toner;

2. 2. The image forming method according to claim 1, wherein the molar ratio of the 1,4-butanediol in the first alcohol component is 65 mol % or less.

3. 3. The image forming method according to claim 1, wherein the molar ratio of the 1,4-butanediol in the first alcohol component is 53 mol % or more.

4. 4. The image forming method according to claim 1, wherein the first binder resin has no endothermic peak in differential scanning calorimetry.

5. 5. The image forming method according to claim 1, wherein the first binder resin is amorphous.

6. The image forming method according to claim 1 , wherein the first alcohol component contains a branched diol.

7. 7. The image forming method according to claim 6, wherein the branched diol is an alkylene oxide adduct of bisphenol A.

8. 8. The image forming method according to claim 7, wherein the alkylene oxide adduct of bisphenol A is at least one of an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A.

9. 9. The image forming method according to claim 8, wherein the alkylene oxide adduct of bisphenol A is an ethylene oxide adduct of bisphenol A.

10. the first alcohol component contains only the 1,4-butanediol and the alkylene oxide adduct of bisphenol A; The image forming method according to claim 7 , wherein the first carboxylic acid component contains only the polyvalent carboxylic acid.

11. 11. The image forming method according to claim 10, wherein in the first alcohol component, a molar ratio of the alkylene oxide adduct of bisphenol A to the 1,4-butanediol is 35 / 65 or more and 70 / 30 or less.

12. 12. The image forming method according to claim 10, wherein a molar ratio of the polyvalent carboxylic acid to a total amount of the 1,4-butanediol and the alkylene oxide adduct of bisphenol A in the first alcohol component is 80 / 100 or more and 90 / 100 or less.

13. 13. The image forming method according to claim 1, wherein the toner has an endothermic peak in differential scanning calorimetry.

14. 14. The image forming method according to claim 13, wherein the endothermic peak temperature of the toner is 50° C. or more and 250° C. or less.

15. 15. The image forming method according to claim 13, wherein the toner has an exothermic peak lower than the endothermic peak in differential scanning calorimetry.

16. the endothermic peak temperature of the toner is 120° C. or more and 200° C. or less; 16. The image forming method according to claim 15, wherein the exothermic peak temperature of the toner is less than 120°C.

17. 17. The image forming method according to claim 1, wherein the second binder resin has an endothermic peak in differential scanning calorimetry.

18. 18. The image forming method according to claim 17, wherein the endothermic peak temperature of the second binder resin is 50° C. or more and 250° C. or less.

19. 19. The image forming method according to claim 1, wherein the second binder resin is contained in an amount of 10% by mass or more and 25% by mass or less in a total amount of the first binder resin and the second binder resin.

20. 20. The image forming method according to claim 1, wherein the second alcohol component contains 1,4-butanediol.

21. 21. The image forming method according to claim 20, wherein the second alcohol component contains 1,4-butanediol and an alkylene oxide adduct of bisphenol A.

22. 22. The image forming method according to claim 1, wherein the fixing solution contains an ester-based softening agent.

23. The image forming method according to claim 22, wherein in the applying step, the ester-based softener softens the first binder resin and the second binder resin.

24. 24. The image forming method according to claim 22, wherein the ester-based softening agent is a dibasic acid ester.

25. 25. The image forming method according to claim 22, wherein the ester-based softening agent is a carbonate ester.

26. 26. The image forming method according to claim 25, wherein the carbonate ester is propylene carbonate.

27. 27. The image forming method according to claim 22, wherein the ester-based softener is an aliphatic dicarboxylic acid ester.

28. 28. The image forming method according to claim 27, wherein the aliphatic dicarboxylic acid ester is at least one selected from the group consisting of diethyl sebacate, diethyl succinate, diethoxyethyl succinate, and dicarbitol succinate.

29. 29. The image forming method according to claim 22, wherein the boiling point of the ester-based softening agent is 180[deg.] C. or higher.

30. 30. The image forming method according to claim 1, wherein the polycarboxylic acid is an aromatic dicarboxylic acid.

31. 31. The image forming method according to claim 30, wherein the aromatic dicarboxylic acid is terephthalic acid.

32. A photosensitive drum; a transfer device that transfers the toner on the photosensitive drum, the toner including a first binder resin and a second binder resin, onto a sheet; an application device that applies a fixing liquid capable of softening the first binder resin and the second binder resin to the sheet onto which the toner has been transferred; Equipped with the first binder resin is a condensate of a first alcohol component containing 1,4-butanediol and a first carboxylic acid component containing a polyvalent carboxylic acid, and a molar ratio of the 1,4-butanediol in the first alcohol component is 30 mol% or more; the second binder resin is a condensate of a second alcohol component containing a linear diol having 2 to 6 carbon atoms and a second carboxylic acid component containing a polyvalent carboxylic acid, 2. An image forming apparatus according to claim 1, wherein the number of domains of the second binder resin having a size exceeding a cumulative 85% particle size based on the number of the toner particles is 0.

Images