CN106896654B - Toner and image forming apparatus - Google Patents

Abstract

The present invention relates to a toner. A toner is provided that includes toner particles containing a binder resin, a wax, and a colorant. The softening point of the toner is 80 ℃ to 140 ℃. The average circularity of the toner is 0.940 or more. The integral value of the stress of the toner at 150 ℃ measured by using a viscosity tester is 78 g.m/sec or more.

Description

Toner and image forming apparatus

Technical Field

The present invention relates to a toner suitable for a recording method using electrophotography, electrostatic recording, toner jet system recording, or the like.

Background

In view of energy and space saving, there has recently been a demand for downsizing of the main body of printers and copiers. Simplification of the fixing apparatus is one of the methods of downsizing the main body. Film fixing, which can make simplification of the heat source and the apparatus configuration easy, is a method of simplifying the fixing apparatus. In the film fixing, in addition to making simplification of the heat source and the apparatus configuration easy, as a result of using the film as the fixing member, the heat conductivity is improved. Therefore, the initial printout time can be shortened. However, since the film is used by being pressed against the roller under a relatively high pressure, the film tends to wear in long-term use.

A toner exhibiting satisfactory low-temperature fixability even at low pressure is required to solve the problem. However, a problem caused when the pressure at the fixing nip (fixing nip) is lowered and an image having a high print rate is output at high speed is that: the toner tends to peel off from the paper (cold offset) due to a small amount of heat supplied to the toner and insufficient toner deformation.

A technique of ensuring that the interfacial adhesion or the internal cohesion, which is measured by a specific measurement method, is appropriate has been suggested as a method of improving the cold offset resistance of the toner.

Japanese patent application laid-open No. 2006-330706 proposes a toner in which the interfacial adhesion force (Fr) between the toner and polytetrafluoroethylene, measured by a specific measurement method, is 1.0N or more and 3.5N or less and the internal cohesive force (Ft) of the toner, similarly measured by the specific measurement method, is 10N or more and 18N or less. Further, japanese patent application laid-open No. 2014-071332 proposes a toner in which an internal cohesion force (F) is 5N or more and 10N or less and an interfacial adhesion force (F) is 0.5N or more and 1N or less, the force being measured using a specific measurement method.

Disclosure of Invention

The toner disclosed in japanese patent application laid-open No. 2006-330706 has excellent cold offset resistance in a general fixing device configuration. However, in the case where an image having a high print ratio is output at high speed in addition to a further reduction in pressure at the fixing nip, the toner exhibits poor fusing property under small pressurization and heat and cold offset resistance is still insufficient.

Further, the measurement described in japanese patent application laid-open No. 2014-071332 involves the steps of pressurizing and heating the toner, but in addition to the fact that a test stage (stage) carrying the toner is heated, the amount of heat supplied to the toner within a pressurizing and heating time of 30 seconds deviates from the instantaneous amount of heat supplied in actual fixing. Therefore, when an image having a high print ratio is output at high speed with a fixing nip of low pressure, even a toner having the above physical properties exhibits insufficient cold offset resistance.

The present invention provides a toner that solves the above problems. More specifically, a toner having excellent cold offset resistance and hot offset resistance when an image having a high print ratio is output at a high speed even in a fixing unit of a low pressure type is provided.

Based on the results of extensive studies, the present inventors have found that the above-mentioned problems can be solved by using a tack tester (tack tester), and under the condition of instantaneously supplying a large amount of heat, adjusting the instantaneous melting characteristics of the toner to a specific value or more and also adjusting the average circularity and softening point of the toner to specific ranges. This finding led to the completion of the present invention.

Thus, the present invention provides a toner comprising toner particles comprising a binder resin, a wax and a colorant, wherein

The softening point of the toner is 80 ℃ or higher and 140 ℃ or lower;

the average circularity of the toner is 0.940 or more; and

an integrated value of stress of the toner at 150 ℃ when measured using a viscosity tester on a toner pellet obtained by compressing the toner is 78g · m/sec or more.

The present invention provides a toner having excellent cold offset resistance and hot offset resistance even in a fixing unit of a low pressure type when an image having a high print ratio is output at a high speed.

Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the accompanying drawings).

Drawings

Fig. 1 is a schematic diagram of a viscosity tester for measuring the integral value of stress.

Detailed Description

The toner of the present invention includes toner particles containing a binder resin, a wax, and a colorant. Further, the toner is specifically characterized in that: the softening point of the toner is within a specific range and the average circularity and the integral value of the stress of the toner measured by using a viscosity tester for toner pellets obtained by compressing the toner are each above a specific value.

The present inventors consider the following as a reason why the present invention solves the above-described problems. In order to obtain excellent cold offset resistance, it is important that the toner is appropriately deformed when receiving heat and pressure and that the surfaces of the toner particles are melted and bonded together by heat. In particular, since thermal deformation of the toner does not easily occur in the fixing nip of low pressure, the importance of the surface adhesiveness of the toner during fusing increases. As for the adhesive force between toner particles during fusing, the adhesive force increases due to an increase in the contact area of the toner particles caused by instantaneous plasticization and deformation of the toner itself. Furthermore, there may also be a relationship with the surface properties of the toner particles during fusing.

Therefore, in order to increase the cold offset resistance at low pressure, it is necessary to increase the adhesive force between toner particles in response to the transient heat. Therefore, the adhesive force between toner particles in response to the instantaneous heat can be increased by measuring the integral value of the stress of the toner using a viscosity tester and controlling the value.

It is important that the measurement with the tack tester is performed under the following specific conditions.

Pressurizing temperature: 150 ℃ C

Pressurization and holding time: 1s

Thus, it was found that the value of the integral value of the stress closely related to the cold offset resistance can be obtained by measurement under the above-mentioned conditions. The present inventors speculate as follows with respect to details.

First, regarding the pressing temperature, since heat is taken away by the continuous passage of the paper medium, the amount of heat transferred to the paper, which indicates the amount of heat supplied to the toner, is estimated to correspond to a temperature lower than the actual fixing set temperature. Thus, a suitable pressing temperature is 150 ℃, and where the pressing temperature is higher or lower than 150 ℃, the association with cold offset resistance tends to be weakened in the image forming apparatus of the low-pressure system. In addition, it is envisaged that in the actual case of media passing through the fixing nip, it is preferable that the pressing and holding time is as short as 1 s.

As for the softening point of the toner, adjusting the softening point to a certain range is important for improving the cold offset resistance. In the case where the softening point is too low, a phenomenon (hot offset) in which the toner peels off when image output is performed at a high temperature is more likely to occur, and in the case where the softening point is too high, thermal deformation is less likely, and peeling is likely to occur with a small amount of heat.

Increasing the average circularity is also necessary to obtain excellent cold offset resistance. Where the average circularity is high, the toner on the medium will be more densely packed at high print output. As a result, voids between toner particles are less likely to occur, and thus heat loss is reduced and heat is certainly transferred to the toner.

For the above reasons, it has been found that, when the above conditions are satisfied, a toner having excellent cold offset resistance even at low pressure can be obtained. This finding led to the completion of the present invention. In the present invention, for example, a range of a pressure of 69kg · m/sec or less represents a specific numerical value of the low pressure.

Hereinafter, the present invention is described in more detail, but is not limited to the description.

In the present invention, it is necessary that the integrated value of stress at 150 ℃ is 78g · m/sec or more when the toner pellet obtained by compressing the toner is measured using a viscosity tester. When the value is less than 78g · m/sec, the toner has poor adhesion during fusing and cannot obtain excellent cold offset resistance at low pressure. The preferable range of the integral value of stress at 150 ℃ can provide a desired effect when the value is 78g · m/sec or more, but when the toner is adjusted to a practicable range, the integral value of stress is preferably 200g · m/sec or less while the softening point is controlled to a desired range. A range of 80 g.m/sec or more and 130 g.m/sec or less is more preferable.

In addition to adjusting the amounts or types of the binder resin, crystalline polyester, and wax, a method of adjusting the thermal conductivity of the toner may be used as a method of controlling the integral value of the stress of the toner at 150 ℃.

Further, in order to obtain the cold offset resistance described above, it is necessary that the softening point of the toner is 80 ℃ or more and 140 ℃ or less and the average circularity of the toner is 0.940 or more. In the case where the softening point is less than 80 ℃, the pressure at the nip end portion increases even when the fixing nip is under low pressure. As a result, in the case where an image is output at a high temperature, hot offset mainly at the end portion is liable to occur. Further, in the case where the softening point is more than 140 ℃, the deformation in the nip portion is insufficient. As a result, the toner is easily peeled off from the medium, and the cold offset resistance tends to decrease. Therefore, the desired effect at low pressure cannot be obtained. The softening point is preferably 90 ℃ or higher and 120 ℃ or lower.

Where the average circularity of the toner is less than 0.940, a large number of voids occur between toner particles on the medium and heat is easily dissipated. As a result, the cold offset resistance at high-speed output tends to decrease. The upper limit of the average circularity is not particularly limited, but is usually 1.00 or less. It is more preferable that the lower limit is 0.950 or more because heat loss due to the above-described voids between toner particles is more easily suppressed.

The softening point of the toner may be controlled by the type or amount of the crosslinking agent. Further, when the toner is produced by the suspension polymerization method described below, the softening point may also be adjusted by the type or amount of the initiator and the reaction temperature.

Further, the average circularity can be set within a desired range by a toner production method, for example, a thermal spheroidizing method after a pulverization method, or a suspension or emulsion polymerization method. In addition to adjusting the average circularity, from the viewpoint of improving dispersibility of materials of crystalline polyesters and ester waxes and the like preferably used in the present invention, it is preferable that the toner is produced by a method of suspending in an aqueous medium, more preferably by using a suspension polymerization method.

Specific materials that can be used for the toner of the present invention will be explained hereinafter.

From the viewpoint of controlling the integral value of stress to a desired value, it is preferable that the toner particles used in the present invention include a crystalline polyester.

The structure of the crystalline polyester is described below. The crystalline polyester that can be used in the present invention preferably has a long hydrocarbon chain as a partial structure of the main chain to a certain extent. It is preferable that the crystalline polyester has a partial structure represented by the following formula (1).

Formula (1)

Wherein m is an integer from 4 to 14; n is an integer from 6 to 16.

The length of the main chain is determined by the values of m and n in the partial structure, and from the viewpoint of encapsulating the crystalline polyester in the toner in an aqueous medium and improving storage stability, it is preferable that m be 4 or more and n be 6 or more. Further, from the viewpoint of increasing the solubility of the crystalline polyester itself, it is particularly preferable that m is 14 or less and n is 16 or less. In the partial structure, it is preferable to include the partial structure in an amount of 50 mass% or more with respect to the entire crystalline polyester from the viewpoint of setting the integrated value of the stress within a desired numerical range.

A known crystalline polyester can be used, but a polycondensate of an aliphatic dicarboxylic acid and an aliphatic diol is preferable. Even more preferably saturated polyesters. Examples of suitable monomers are provided below.

Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid.

Specific examples of the aliphatic diol include ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propanediol, 1, 3-propanediol, dipropylene glycol, trimethylene glycol, neopentyl glycol, 1, 4-butanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, and 1, 12-dodecanediol.

The crystalline polyester used in the present invention can be produced by a general polyester synthesis method. For example, the crystalline polyester can be obtained by performing esterification or transesterification of a dicarboxylic acid component and a diol component, and then performing polycondensation under reduced pressure or by an ordinary method by introducing nitrogen gas.

During the esterification or transesterification, a usual esterification catalyst or transesterification catalyst such as sulfuric acid, t-butyl titanium butoxide, dibutyltin oxide, manganese acetate and magnesium acetate may be used as necessary. Further, polymerization can be carried out using a known polymerization catalyst, for example, t-butyltitanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide and germanium dioxide. The polymerization temperature and the amount of the catalyst are not particularly limited and may be selected as needed.

The catalyst is preferably a titanium catalyst, more preferably a chelate-type titanium catalyst. This is because the titanium catalyst has suitable reactivity and can give a polyester having a molecular weight distribution desired in the present invention.

The weight average molecular weight (Mw) of the crystalline polyester is preferably 10,000 or more and 40,000 or less, and more preferably 10,000 or more and 30,000 or less. When the weight average molecular weight (Mw) is within the above range, the plasticizing effect of the crystalline polyester can be immediately obtained in the fixing step while maintaining the high crystallinity of the crystalline polyester.

The weight average molecular weight (Mw) of the crystalline polyester can be controlled by various production conditions of the crystalline polyester.

Further, when dispersibility in the toner is taken into consideration, the acid value of the crystalline polyester is preferably controlled to a low value. Specifically, the acid value is 8.0mgKOH/g or less, more preferably 5.0mgKOH/g or less, and still more preferably 3.5mgKOH/g or less.

The amount of the crystalline polyester is preferably 1.0 part by mass or more and 30.0 parts by mass or less per 100.0 parts by mass of the binder resin.

The wax is explained below.

First, in order to control the integral value of the stress to a desired value, it is preferable that the wax includes an ester wax. According to the inventors' idea about this feature, in the case where the ester wax is included in the toner, the dispersibility of the crystalline polyester in the toner is improved, and the low-molecular component of the ester wax is also dissolved first during heating, thereby assisting the exposure of the crystalline polyester on the surface of the toner.

In addition, known ester waxes may be used in the present invention. Suitable examples include: waxes containing fatty acid esters as a main component, such as carnauba wax and montanic acid ester wax; waxes obtained by partially or completely deoxidizing acid components derived from fatty acid esters, such as deoxidized carnauba wax; a methyl ester compound having a hydroxyl group obtained by, for example, hydrogenation of vegetable oils and fats; saturated fatty acid monoesters such as stearyl stearate and behenyl behenate; diesters of saturated aliphatic dicarboxylic acids with saturated aliphatic alcohols such as dibehenyl sebacate, distearyl dodecandioate and distearyl octadecanedioate; and diesters of saturated aliphatic diols such as nonadiol dibehenate and dodecanediol distearate with saturated aliphatic monocarboxylic acids.

Among these waxes, from the viewpoint of improving the dispersibility of the crystalline material and controlling the integral value of stress to a more preferable value, it is preferable to include a bifunctional ester wax (diester) having two ester bonds in the molecular structure.

The bifunctional ester wax is an ester compound of a dihydric alcohol and an aliphatic monocarboxylic acid or an ester compound of a dihydric carboxylic acid and an aliphatic monohydric alcohol.

Specific examples of aliphatic monocarboxylic acids include myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, oleic acid, 11-octadecenoic acid, linoleic acid, and linolenic acid.

Specific examples of the aliphatic monohydric alcohol include myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, ceryl alcohol, octacosyl alcohol, and triacontanol.

Specific examples of the dicarboxylic acid include butanedioic acid (succinic acid), pentanedioic acid (pentanedioic acid), hexanedioic acid (hexanedioic acid) (adipic acid)), heptanedioic acid (heptanedioic acid)), octanedioic acid (octanedioic acid) (suberic acid), nonanedioic acid (nonanedioic acid) (azelaic acid), decanedioic acid (decanodioic acid), dodecanedioic acid (sebasic acid), tridecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, phthalic acid, isophthalic acid, and terephthalic acid.

Specific examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 10-decanediol, 1, 12-dodecanediol, 1, 14-tetradecanediol, 1, 16-hexadecanediol, 1, 18-octadecanediol, 1, 20-eicosanediol, 1, 30-triacontanediol, diethylene glycol, dipropylene glycol, 2, 4-trimethyl-1, 3-pentanediol, neopentyl glycol, 1, 4-cyclohexanedimethanol, spiroglycol, 1, 4-benzenediol, bisphenol A and hydrogenated bisphenol A.

In the present invention, other waxes than the ester wax may be used together therewith within a range not impairing the effects of the present invention.

Known waxes may be used as the other wax to be combined with the ester wax, but from the viewpoint of releasability of the fixing roller and the toner, an aliphatic hydrocarbon wax such as a fischer-tropsch wax may be advantageously used.

The mass ratio (a)/(B) of the ester wax (a) to the aliphatic hydrocarbon wax (B) in the toner is preferably 0.25 or more and 4.0 or less, and more preferably 0.40 or more and 2.3 or less.

The amount of the wax is preferably 5.0 parts by mass or more and 30.0 parts by mass or less per 100.0 parts by mass of the binder resin. Further, the amount of the ester wax is preferably 1.0 part by mass or more and 30.0 parts by mass or less per 100.0 parts by mass of the binder resin.

Examples of the binder resin used in the toner of the present invention include: homopolymers of styrene and its substituted products such as polystyrene and polyvinyltoluene; such as styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-butadiene copolymer, styrene copolymers such as styrene-maleic acid copolymers and styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, and polyacrylic resin. These resins may be used alone or in combination of plural kinds thereof. Among them, a styrene-based copolymer represented by styrene-butyl acrylate is preferable from the viewpoint of controlling the integral value of stress in a desired range.

More preferred are styrene-acrylic resins, and examples thereof include styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer and styrene-dimethylaminoethyl methacrylate copolymer.

Examples of the colorant usable in the present invention include the following organic pigments, organic dyes and inorganic pigments.

Examples of the cyan colorant include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds and basic dye lake compounds. Specific examples are provided below. C.i. pigment blue 1,7, 15:1, 15:2, 15:3, 15:4, 60, 62 and 66.

Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds and perylene compounds. Specific examples are provided below. C.i. 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, 254, and c.i. pigment violet 19.

Examples of the yellow coloring agent include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds and allylamide compounds. Specific examples are provided below. 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.

Examples of the black colorant include carbon black and a colorant toned black by using the foregoing yellow colorant, magenta colorant, cyan colorant, and magnetic body.

These colorants can be used alone or as a mixture, and also in the state of a solid solution. The colorant used in the present invention is selected in consideration of hue angle, chroma, lightness, lightfastness, OHP transparency and dispersibility in toner particles.

Among the above colorants, a magnetic material is preferable from the viewpoint of adjusting the thermal conductivity of the toner to a desired range. In view of controlling the thermal conductivity, it is preferable that the toner of the present invention is produced in an aqueous medium.

The amount of the colorant added is preferably 1.0 part by mass or more and 20.0 parts by mass or less per 100 parts by mass of the binder resin. When the magnetic body is used, the amount thereof is preferably 20.0 parts by mass or more and 200.0 parts by mass or less, and more preferably 40.0 parts by mass or more and 150.0 parts by mass or less per 100 parts by mass of the binder resin.

The value of the thermal conductivity of the toner of the present invention is preferably 0.190W/mK or more and 0.300W/mK or less, and more preferably 0.230W/mK or more and 0.270W/mK or less. In the case where the thermal conductivity is 0.190W/mK or more, heat is easily transferred between toner particles, adhesiveness of the toner during fusing is improved, and the toner is less likely to peel off from the medium even when the fixed image is rubbed. Further, in the case where the thermal conductivity is 0.300W/mK or less, the hot offset resistance of the fixing nip end portion in which the pressure during fixing at a high temperature is high is improved.

The thermal conductivity of the toner can be controlled by the amount of the magnetic material, the particle diameter of the magnetic material, and the surface treatment of the magnetic material.

When the magnetic body is used for the toner of the present invention, the magnetic body preferably includes, as a main component, magnetic iron oxide such as ferroferric oxide and γ -iron oxide, and may include such elements as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. The BET specific surface area of these magnetic bodies determined by nitrogen adsorption method is preferably 2m²G to 30m²Per g, and more preferablyIs 3m²G to 28m²(ii) in terms of/g. Further, the mohs hardness is preferably 5 to 7. The shape of the magnetic body may be polyhedral, octahedral, hexahedral, spherical, acicular, and scaly, but from the viewpoint of increasing the image density, a shape having small anisotropy, such as polyhedral, octahedral, hexahedral, and spherical, is preferable.

The number average particle diameter of the magnetic material is preferably 0.10 to 0.40. mu.m. Although a smaller particle diameter of the magnetic body generally gives an increased coloring power, the above range is preferable from the viewpoint of preventing aggregation of the magnetic body and ensuring uniform dispersion of the magnetic body in the toner. When the number average particle diameter is 0.10 μm or more, the magnetic material itself is not liable to have a reddish black color. In particular, reddish color cannot be conspicuous in a halftone image, and a high-quality image can be obtained. At the same time, when the number average particle diameter is 0.40 μm or less, the coloring power of the toner is improved and uniform dispersion is promoted in the suspension polymerization method.

The number average particle diameter of the magnetic body can be measured by using a transmission electron microscope. More specifically, toner particles to be observed were sufficiently dispersed in an epoxy resin, and then a cured product was obtained by curing for 2 days in an atmosphere at a temperature of 40 ℃. The resultant cured product was cut into a thin sample with a microtome, and the particle diameters of 100 magnetic particles present in the field of view were measured under a Transmission Electron Microscope (TEM) at an image magnification of 10,000 times to 40,000 times. Then, the number average particle diameter was calculated based on the equivalent diameter of a circle having the same area as the projected area of the magnetic material. The particle size can also be measured with an image display device.

For example, a magnetic body to be used in the toner of the present invention can be prepared by the following method. Initially, a base such as sodium hydroxide is added to an aqueous solution of a ferrous salt in an amount equivalent to or greater than the iron component to prepare an aqueous solution of ferrous hydroxide. Air is blown into the prepared aqueous solution while maintaining its pH at 7 or more, the oxidation reaction of ferrous hydroxide is performed while heating the aqueous solution to 70 ℃ or more, and seed crystals serving as nuclei of the magnetic iron oxide powder are first generated.

Then, an aqueous solution including ferrous sulfate in an amount of about 1 equivalent determined based on the addition amount of the aforementioned base is added to the slurry including the seed crystal. The reaction of ferrous hydroxide is performed while maintaining the pH of the liquid at 5 to 10 and blowing air, and magnetic iron oxide powder is grown on the seed crystal as nuclei. At this time, the shape and magnetic properties of the magnetic body can be controlled by selecting pH, reaction temperature and stirring conditions as appropriate. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but it is preferable that the pH of the liquid is not less than 5. The magnetic body can be obtained by filtering, washing, and drying the magnetic body thus obtained by means of an ordinary method.

Further, when the toner is produced in an aqueous medium in the present invention, it is particularly preferable that the surface of the magnetic body is hydrophobized. In the case of surface treatment by a dry method, the treatment of the magnetic body after washing, filtration and drying is carried out by using a coupling agent. In the case of surface treatment by a wet method, a dried substance is redispersed after completion of an oxidation reaction, or iron oxide obtained by washing and filtering after completion of an oxidation reaction is redispersed in another aqueous medium without drying, and then subjected to a coupling treatment. In the present invention, the dry method and the wet method may be selected as appropriate.

Examples of the coupling agent that can be used in the surface treatment of the magnetic body in the present invention include a silane coupling agent, a silane compound, and a titanium coupling agent. It is preferable to use a silane coupling agent and a silane compound. Examples thereof are represented by the following general formula (I).

R_mSiY_n (I)

[ wherein R represents an alkoxy group; m represents an integer of 1 to 3; y represents a functional group such as an alkyl group, a phenyl group, a vinyl group, an epoxy group, and a (meth) acryloyl group; n represents an integer of 1 to 3. However, m + n is 4. ]

Examples of the silane coupling agent or silane compound represented by the general formula (I) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (beta-methoxyethoxy) silane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, gamma-aminopropyltriethoxysilane, N-phenyl-gamma-aminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, vinyltriethoxysilane, and the like, Diphenyldiethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, trimethylmethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, hydroxypropyltrimethoxysilane, n-hexadecyltrimethoxysilane and n-octadecyltrimethoxysilane. In the present invention, it is preferable to use a compound in which Y in the general formula (I) is an alkyl group. Among them, from the viewpoint of obtaining a desired value of thermal conductivity, it is preferable that Y is an alkyl group having 3 or more and 6 or less carbon atoms, and an alkyl group having 3 or 4 carbon atoms is particularly preferable.

When the silane coupling agent is used, the treatment may be performed with one agent or by using a plurality of types thereof. When a plurality of types thereof are used, the treatment with each coupling agent may be carried out independently or simultaneously.

The total treating amount of the coupling agent to be used is preferably 0.9 to 3.0 parts by mass per 100 parts by mass of the magnetic body. The amount of the treating agent may be adjusted depending on the surface area of the magnetic body, the reactivity of the coupling agent, and the like.

In the present invention, other coloring agents may be used together with the magnetic body. Examples of the coloring agent that can be used together with the magnetic body include the above-mentioned publicly known dyes and pigments and also magnetic and non-magnetic inorganic compounds. Specific examples include ferromagnetic metal particles such as cobalt and nickel, and alloys obtained by adding chromium, manganese, copper, zinc, aluminum, and rare earth metals thereto. Particles of hematite and the like, titanium black, nigrosine dyes/pigments, carbon black, phthalocyanines, and the like may also be used. It is preferable that these colorants may be further subjected to surface treatment.

The amount of the magnetic body in the toner can be measured using a thermal analysis apparatus TGA 7 manufactured by PerkinElmer, inc. The measurement was performed in the following manner. The toner was heated from room temperature to 900 ℃ at a temperature rise rate of 25 ℃/min under a nitrogen atmosphere. The mass reduction rate (%) from 100 ℃ to 750 ℃ was regarded as the amount of the binder resin, and the residual mass was regarded as the approximate amount of the magnetic body.

Further, the weight average particle diameter (D4) of the toner produced according to the present invention is preferably 3.0 μm or more and 12.0 μm or less, and more preferably 4.0 μm or more and 10.0 μm or less. When the weight average particle diameter (D4) is 3.0 μm or more and 12.0 μm or less, good fluidity is obtained and the latent image can be faithfully developed.

The toner of the present invention can also be produced by thermally spheroidizing the toner particles obtained by the pulverization method, but a method of producing a toner in an aqueous medium is preferable from the viewpoint of controlling the state of existence of materials such as crystalline polyester and ester wax. In particular, the suspension polymerization method is preferable because the crystalline polyester is obtained in a finely dispersed state and the progress of crystallization can be easily controlled.

The suspension polymerization method is explained below.

In the method of producing a toner by using the suspension polymerization method, the polymerizable monomer composition is obtained by uniformly dissolving or dispersing the polymerizable monomer constituting the binder resin, the wax, and the colorant (and also, as necessary, the crystalline polyester, the polymerization initiator, the crosslinking agent, the charge control agent, and other additives). The subsequent treatment includes a step of dispersing the polymerizable monomer composition in a continuous phase (for example, an aqueous phase) including a dispersant by using a suitable stirrer and forming particles of the polymerizable monomer composition in an aqueous medium, and a step of polymerizing the polymerizable monomer included in the particles of the polymerizable monomer composition. In a toner obtained by a suspension polymerization method (hereinafter may be referred to as "polymerized toner"), individual toner particles have a substantially spherical shape. As a result, the distribution of the charge amount is also relatively uniform, and therefore, improvement in image quality can be expected. In the step of polymerizing the polymerizable monomer, the polymerization temperature may be set to 40 ℃ or higher, and is usually set to 50 ℃ or higher and 90 ℃ or lower.

Examples of the polymerizable monomer constituting the polymerizable monomer composition are listed below.

Thus, examples of the polymerizable monomer include: styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methoxystyrene and p-ethylstyrene; acrylate monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate; methacrylate-based monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate; and also acrylonitrile, methacrylonitrile and acrylamide. These monomers may be used alone or in a mixture. Among these monomers, from the viewpoint of toner development characteristics and durability, it is preferable that styrene is used alone or in a mixture with other monomer processes.

A polymerization initiator having a half-life of 0.5h to 30h in polymerization reaction is preferably used in the production of the toner of the present invention by the polymerization method. Where the polymerization reaction is carried out by adding 0.5 to 20 parts by mass of a polymerization initiator per 100 parts by mass of the polymerizable monomer, a polymer having a maximum value of molecular weight between 5,000 and 50,000 can be obtained and a desired strength and suitable melting characteristics can be imparted to the toner.

Examples of specific polymerization initiators include: azo or diazo polymerization initiators such as 2,2 '-azobis- (2, 4-dimethylvaleronitrile), 2' -azobisisobutyronitrile, 1 '-azobis (cyclohexane-1-carbonitrile), 2' -azobis-4-methoxy-2, 4-dimethylvaleronitrile and azobisisobutyronitrile; and for example benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate. Peroxide polymerization initiators such as cumene hydroperoxide, 2, 4-dichlorobenzoyl peroxide, lauroyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, di (2-ethylhexyl) peroxycarbonate and di (sec-butyl) peroxycarbonate.

When the toner of the present invention is produced by a polymerization method, a crosslinking agent may be added, and a preferable addition amount thereof is 0.001 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the polymerizable monomer.

Compounds having more than two polymerizable double bonds are mainly used as crosslinking agents. Examples thereof include: aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1, 3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and compounds having three or more vinyl groups. These compounds may be used alone or in combination of two or more thereof.

When the medium used during polymerization of the polymerizable monomer is an aqueous medium, the dispersion stabilizer can be used to stabilize the particles of the polymerizable monomer composition. The following dispersion stabilizers can be used.

Examples of the inorganic dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina.

Examples of the organic dispersion stabilizer include polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose, sodium carboxymethyl cellulose, and starch.

In addition, commercially available nonionic, anionic and cationic surfactants can also be used. Examples of suitable surfactants include sodium lauryl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, and potassium stearate.

When an inorganic dispersion stabilizer that is hardly water-soluble is used to prepare an aqueous medium in the present invention, the addition amount of the dispersion stabilizer is preferably 0.2 to 2.0 parts by mass per 100.0 parts by mass of the polymerizable monomer. Further, it is preferable that the aqueous medium is prepared using 300 parts by mass to 3,000 parts by mass of water per 100 parts by mass of the polymerizable monomer composition.

When such an aqueous medium in which an inorganic dispersion stabilizer which is difficult to be water-soluble is dispersed is prepared in the present invention, a commercially available dispersion stabilizer may be used as it is. In addition, in order to obtain a dispersion stabilizer having a fine and uniform particle size, an inorganic dispersion stabilizer which is hardly water-soluble may be generated in an aqueous medium such as water under high-speed stirring. More specifically, when tricalcium phosphate is used as the dispersion stabilizer, a preferable dispersion stabilizer can be obtained by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring to form fine particles of tricalcium phosphate.

In the present invention, the integrated value can be easily controlled to the above range by using the method of controlling the integrated value of the stress of the toner described below.

For example, after the resin particles have been obtained by polymerizing the polymerizable monomer, a dispersion in which the resin particles are dispersed in an aqueous medium is heated to a temperature higher than the melting points of the crystalline polyester and the wax. However, when the polymerization temperature is higher than the melting point, the operation is not required.

Regarding the cooling rate in the subsequent cooling step, the preferred range thereof in the present invention will be explained for the entire production process of the toner, not only for the polymerization process.

Attention is focused here on a method for producing a toner with the object of crystallizing a crystalline substance, particularly a crystalline polyester.

For example, when the toner is produced by a pulverization method, suspension polymerization, or emulsion polymerization, it is preferable to include a step in which the temperature is increased at a time so that the crystalline polyester or wax is melted, followed by cooling to normal temperature. As for the cooling step, the molecular motion in the crystalline polyester liquefied by increasing the temperature is attenuated as the temperature is lowered, and crystallization starts as the crystallization temperature is approached. On continued cooling, crystallization proceeds and complete solidification is achieved at normal temperature. According to the studies conducted by the present inventors, the crystallinity of a crystalline substance differs depending on the cooling rate.

More specifically, in the case where the temperature is cooled at a rate of 5.0 ℃/minute or more from a temperature sufficiently high for melting the crystalline polyester and wax (for example, 100 ℃) to the glass transition temperature or less of the toner, the crystallinity of the included crystalline substance tends to increase. Under the above cooling condition, the integral value of the stress of the toner is easily controlled to the above range.

Still more specifically, as noted above, a sufficiently high cooling rate is a rate sufficiently higher than 5.0 ℃/minute. Such cooling rate is preferably 10.0 ℃/minute or more, more preferably 30.0 ℃/minute or more, and still more preferably 50.0 ℃/minute or more. The upper limit of the cooling rate is about 3,000 c/min, at which time the effect is saturated.

It is also preferable that the dispersion is cooled to a temperature below the glass transition temperature of the toner at a sufficiently high cooling rate, then held at a temperature below the glass transition temperature of the toner for 30 minutes or more, and then cooled at a relatively low cooling rate of 1.0 ℃/minute or less.

As a result of being held at a temperature of the glass transition temperature or lower of the toner for 30 minutes or longer, annealing is performed and the crystallinity of the crystalline polyester can be increased. The holding time is preferably 100 minutes or more, and more preferably 180 minutes or more. The upper limit of the holding time is about 1,440 minutes, at which the effect is saturated.

In the present invention, cooling at a cooling rate of 1.0 ℃/min or less is referred to as gradual cooling. As a result, the same effect as annealing can be obtained, the crystallinity of the crystalline polyester can be further increased, and the integral value of stress in the toner can be easily controlled to the above range. The cooling rate is preferably 0.50 ℃/min or less, and more preferably 0.01 ℃/min or less. The dispersion including the toner particles obtained by performing the progressive cooling is filtered, washed, and dried by a conventional method, thereby obtaining toner particles.

In the present invention, the toner particles may include a polar resin. Preferred examples of the polar resin include saturated or unsaturated polyester resins. It is also preferable that the polar resin is an amorphous resin.

A polyester resin obtained by polycondensation of the following carboxylic acid component and alcohol component can be used.

Examples of the carboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, fumaric acid, maleic acid, cyclohexane dicarboxylic acid, and trimellitic acid.

Examples of the alcohol component include bisphenol a, hydrogenated bisphenol, ethylene oxide adduct of bisphenol a, propylene oxide adduct of bisphenol a, glycerin, trimethylolpropane and pentaerythritol.

The polyester resin may include urea groups. In the present invention, the weight average molecular weight (Mw) of the polar resin is preferably 4,000 or more and less than 100,000. The amount of the polar resin is preferably 3.0 parts by mass or more and 70.0 parts by mass or less, more preferably 3.0 parts by mass or more and 50.0 parts by mass or less, and still more preferably 5.0 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of the binder resin.

In the present invention, the toner may include a charge control agent. Known charge control agents can be used. In particular, a charge control agent which can increase the charging speed and stably maintain a constant charge amount is preferable. Further, when the toner particles are produced by the direct polymerization method, a charge control agent in which the aqueous medium is substantially insoluble and which has low polymerization inhibitory property is particularly preferable.

Charge control agents capable of controlling toner particles to be negatively charged are exemplified below. Thus, examples of the organometallic compound and the chelate compound include monoazo metal compounds, acetylacetone metal compounds, and metal compounds of aromatic hydroxycarboxylic acids (aromatic oxycarboxylic acids), aromatic dicarboxylic acids, hydroxycarboxylic acids, and dicarboxylic acids. Other examples include aromatic hydroxycarboxylic acids, aromatic monocarboxylic and polycarboxylic acids, metal salts, anhydrides and esters thereof, and phenol derivatives such as bisphenols. In addition, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, and calixarenes can be used.

Meanwhile, the following exemplifies a charge control agent capable of controlling toner particles to be positively charged. Nigrosine and nigrosine modified with a fatty acid metal salt; a guanidine compound; an imidazole compound; tributylbenzylammonium-1-hydroxy-4-naphthalenesulfonate; quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, onium salts such as phosphonium salts which are analogs of quaternary ammonium salts, and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (lakes including phosphotungstic acid, phosphomolybdic acid, phosphotungstomolybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, and ferrocyanide); metal salts of higher fatty acids; and a resin-based charge control agent.

These charge control agents may be used alone or in combination of two or more thereof. Among the charge control agents, metal-containing salicylic acid compounds are preferable, and compounds in which the metal is aluminum or zirconium are particularly preferable. An aluminum compound of 3, 5-di-tert-butylsalicylic acid is a still more preferred charge control agent.

Among the resin-based charge control agents, polymers having sulfonic acid-based functional groups are preferable. As referred to herein, a polymer having sulfonic acid-based functional groups is a polymer or copolymer having sulfonic acid groups, sulfonate groups, or sulfonate groups.

Examples of the polymer or copolymer having a sulfonic acid group, a sulfonate group or a sulfonate ester group include a high molecular type compound having a sulfonic acid group in a side chain. In particular, a polymer type compound including a sulfonic acid group-containing (meth) acrylamide-based monomer and having a glass transition temperature (Tg) of 40 to 90 ℃ and/or a styrene- (meth) acrylate copolymer at a copolymerization ratio of 2% by mass or more, preferably 5% by mass or more is preferable. In this case, the charging stability under high humidity is improved.

As the sulfonic acid group-containing (meth) acrylamide-based monomer, a compound represented by the following general formula (X) is preferable, and specific examples thereof include 2-acrylamido-2-methylpropanesulfonic acid and 2-methacrylamido-2-methylpropanesulfonic acid.

[C2]

(in the general formula (X), R₁Represents a hydrogen atom or a methyl group; r₂And R₃Each represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an allyl group, or an alkoxy group; n is an integer of 1 to 10. )

The charged state of the toner particles can be further improved by including the polymer having a sulfonic acid group in the toner particles at 0.1 part by mass or more and 10.0 parts by mass or less per 100 parts by mass of the binder resin.

The amount of these charge control agents to be added is preferably 0.01 parts by mass or more and 10.00 parts by mass or less per 100.00 parts by mass of the binder resin.

Various organic fine powders or inorganic fine powders may be externally added to the toner particles for the purpose of imparting various properties.

The organic fine powder or inorganic fine powder affects the surface properties and the thermal fusibility of the toner particles, but it is considered that only a small influence is exerted on the integral value of stress by controlling the addition amount of the powder in an appropriate range. Thus, from the viewpoint of adjusting the integral value of the promoting stress to a desired range, the addition amount of the organic fine powder or the inorganic fine powder is preferably 0.01 parts by mass or more and 10.00 parts by mass or less, more preferably 0.02 parts by mass or more and 5.00 parts by mass or less, and still more preferably 0.03 parts by mass or more and 1.00 parts by mass or less per 100.00 parts by mass of the toner particles.

The following materials may be used as the organic fine powder or the inorganic fine powder.

(1) Fluidity imparting agent: silica, alumina, titania, carbon black, and fluorinated carbon.

(2) Grinding agent: metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; and metal salts such as calcium sulfate, barium sulfate, and calcium carbonate.

(3) Lubricant: fluororesin powders such as vinylidene fluoride and polytetrafluoroethylene, and fatty acid metal salts such as zinc stearate and calcium stearate.

(4) Charge control particles: metal oxides such as tin oxide, titanium oxide, zinc oxide, silica, and alumina, and carbon black.

The organic fine powder or inorganic fine powder is used to treat the surface of toner particles to improve the fluidity of the toner and the charging uniformity of the toner. By hydrophobizing the organic fine powder or inorganic fine powder, it is possible to adjust the chargeability of the toner and improve the charging characteristics under a high humidity environment. Therefore, it is preferable to use hydrophobized organic fine powder or inorganic fine powder. Examples of the treating agent for hydrophobizing the organic fine powder or inorganic fine powder 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. These treating agents may be used alone or in combination.

Among them, inorganic fine powder treated with silicone oil is preferable. More preferably, the inorganic fine powder is treated with a silicone oil simultaneously with or after the hydrophobization treatment by the coupling agent. Hydrophobized inorganic fine powder treated with silicone oil is preferable because such powder maintains a high toner charge amount and reduces selective developability even under a high humidity environment. The organic fine powder or the inorganic fine powder may be used alone or in combination of plural kinds thereof.

In the present invention, the BET specific surface area of the organic fine powder or inorganic fine powder is preferably 10m²More than g and 450m²The ratio of the carbon atoms to the carbon atoms is less than g.

The BET specific surface area of the organic fine powder or inorganic fine powder can be determined by a low-temperature gas adsorption method by means of a dynamic constant pressure method according to a BET method (preferably, BET multipoint method). For example, BET specific surface area (m)²/g) can be calculated by allowing the sample surface to adsorb nitrogen and by measuring by the BET multipoint method using a specific surface area meter "GEMINI 2375 ver.5.0" (manufactured by Shimadzu Corporation).

The organic fine powder or inorganic fine powder can be firmly fixed or adhered to the toner particle surface. Examples of external mixers for firmly fixing or attaching the organic fine powder or inorganic fine powder to the surface of the toner particles include henschel mixers, mechanical fusion machines (Mechanofusion), high-speed cyclone mixers (Cyclomix), turbulizers (turbulizers), mixing granulators (flexmix), hybrid mixers (Hybridization), mechanical mixers (Mechanohybrid), and Nobilta. The organic fine powder or inorganic fine powder can be firmly fixed or attached by increasing the peripheral speed of rotation or prolonging the treatment time.

The amount of tetrahydrofuran insolubles (excluding the colorant and inorganic fine powder) in the toner of the present invention is preferably less than 50.0 mass%, more preferably 0.0 mass% or more and less than 45.0 mass%, and still more preferably 5.0 mass% or more and less than 40.0 mass% with respect to the toner components other than the colorant and inorganic fine powder in the toner. When the amount of tetrahydrofuran insolubles is less than 50.0 mass%, the low temperature fixability can be improved.

The amount of tetrahydrofuran insolubles in the toner refers to a mass ratio of the ultrahigh-molecular weight polymer (substantially cross-linked polymer) that becomes insoluble in the tetrahydrofuran solvent. The amount of tetrahydrofuran insolubles can be adjusted by the degree of polymerization and the degree of crosslinking of the binder resin.

< method for measuring integral value of stress of toner >

(1) Preparation of toner pellets

Toner pellets were prepared by placing about 3g of a toner (variable depending on the specific gravity of a sample) in a measuring vinyl chloride ring having an inner diameter of 27mm, by pressurizing at 200kN for 60 seconds using, for example, a sample pressure molding Machine "MAEKAWA Testing Machine" (mfg. co., ltd.) and molding the sample.

(2) Measurement of integral value of stress

The integral value of the stress of the toner was measured by using a viscosity tester "TAC-1000" (manufactured by Rhesca Corporation) according to the device operation manual. A schematic of the adhesion tester is shown in fig. 1.

As a specific measurement method, toner pellets were placed on the sample pressing plate 205, and the probe tip 203 was set to 150 ℃.

By adjusting the head unit 200, the probe tip is then lowered to a position where it can pressurize the toner pellet 204.

The toner pellet was then pressurized under the following conditions, and the stress value at the time of pulling up the probe tip was detected with the load sensor 201.

-pressing speed: 5 mm/sec

-pressure load: 19.7kg m/sec

-pressurized holding time: 1 second

-pull-up speed: 15 mm/sec

The integral value of the stress is calculated by integrating the stress value measured by the load sensor.

More specifically, the separation of the sensor from the pellet can be controlled by the moment (stress value of 0g · m/sec) from the moment of application of the force that separates the sensor from the pellet²Instant) to the instant of separation of the sensor from the particulate material.

< method for measuring average circularity of toner >

The average circularity of the toner was measured using a flow type particle image analyzer "FPIA-3000" (manufactured by sysmex corporation) under the same measurement and analysis conditions as in the calibration process (also measured in the same manner in the case of the magnetic toner).

The specific measurement method is as follows. First, about 20mL of ion-exchanged water from which solid impurities and the like have been removed in advance was put into a glass container. Then, about 0.2mL of a dilution prepared by diluting "Contaminon N" (a 10 mass% aqueous solution of a neutral detergent for washing precision measuring instruments having a pH of 7, which includes a nonionic surfactant, an anionic surfactant and an organic builder; manufactured by Wako Pure Chemical Industries, Ltd.) by about three mass times with ion-exchanged water was added thereto as a dispersant. Then, about 0.02g of the measurement sample was added, and dispersion treatment was performed for 2 minutes using an ultrasonic disperser, thereby obtaining a dispersion liquid for measurement. At this time, the dispersion is suitably cooled so that the temperature thereof is 10 ℃ or more and 40 ℃ or less. By using a desk-top ultrasonic cleaner/disperser (e.g., "VS-150", Velvo-Clear co., ltd.) having an oscillation frequency of 50kHz and an electrical output of 150W as an ultrasonic disperser, a prescribed amount of ion-exchanged water was put into a water tank, and then about 2mL of continon N was added to the water tank.

During the measurement, the aforementioned flow-type Particle image analyzer equipped with "UPLanApro" (magnification: 10 times, numerical aperture: 0.40) as an objective lens was used, and a Particle Sheath (Particle Sheath) "PSE-900A" (manufactured by Sysmex Corporation) was used for the Sheath fluid. The dispersion liquid prepared according to the above-described procedure was introduced into a flow-type particle image analyzer, and 3,000 toner particles were counted using a total number mode in an HPF measurement mode. The average circularity of the toner was determined by setting the binarization threshold value during particle analysis to 85% and defining the analyzed particle diameter to a circle-equivalent diameter of 1.985 μm or more and less than 39.69 μm.

During the measurement, the focus was automatically adjusted using standard latex particles ("RESEARCH AND TEST PARTICLES, Latex Microsphere Suspensions 5200A", manufactured by Duke Scientific Corporation, and diluted with ion-exchanged water) before the measurement started. Subsequently, the focus adjustment is preferably performed every 2 hours from the start of the measurement.

Further, in the present invention, a flow type particle image analyzer which has been calibrated by Sysmex Corporation and issued a calibration certificate by Sysmex Corporation is used. The measurement was performed under the same measurement and analysis conditions as when the calibration certificate was received, except that the analyzed particle diameter was defined as a circle equivalent diameter of 1.985 μm or more and less than 39.69 μm.

The measurement principle of the flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) is to take an image of a flowing particle as a still image and perform image analysis. The sample that has been added to the sample chamber is aspirated by the sample aspiration syringe and fed to the flat sheath flow cell. The sample fed to the sheath flow cell forms a flat stream that is clamped by the sheath fluid. The sample passing through the flat sheath flow cell was illuminated with stroboscopic light at 1/60 second intervals, and an image of the flowing particles could be taken as a still image. Furthermore, because the flow is flat, a focused image is taken. The particle image was captured with a CCD camera and the captured image was processed at an image processing resolution of 512 × 512 pixels (0.37 μm × 0.37 μm per pixel); and by extracting the contour of each particle image, the projected area S and the circumference L of the particle image are measured.

Next, the circle equivalent diameter and circularity are obtained by using the area S and the circumference L. The circle-equivalent diameter refers to the diameter of a circle having the same area as the projected area of the particle image. The circularity is defined as a value obtained by dividing the circumference of a circle obtained from the circle equivalent diameter by the circumference of the particle projection image, and is calculated by the following equation.

Circularity 2 × (pi × S)^1/2/L

When the particle image is circular, the circularity is 1.000. As the degree of unevenness of the circumference of the particle image increases, the circularity decreases. After the circularity of each particle was calculated, the circularity range of 0.200 to 1.000 was divided into 800 parts, and the arithmetic average of the obtained circularities was calculated and regarded as the average circularity.

< method for measuring thermal conductivity >

(1) Preparation of measurement samples

Two cylindrical measurement samples each having a diameter of 25mm and a height of 6mm were prepared by compressing about 5g of a toner (mass varied according to the specific weight of the sample) at about 20MPa for 60 seconds under an environment of 25 ℃ using a lozenge-forming compression device.

(2) Measurement of thermal conductivity

The measuring equipment comprises: thermophysical property meter TPS 2500S by hot plate method

A sample holder: sample holder for room temperature

A sensor: standard attachment (RTK) sensor

Software: hot plate analysis 7

The measurement sample was placed on the mount table of the sample holder for room temperature. The height of the table is adjusted so that the surface of the measurement sample is at the level of the sensor.

A second measurement sample was placed on the sensor, then a piece of attachment metal was placed on it, and pressure was applied using a screw on top of the sensor. The pressure was adjusted to 30cN · m with a torque wrench. It was confirmed that the measurement sample and the sensor were centered directly below the screw.

The hot plate analysis was started and "Bulk (type I)" was selected as the test type.

The input items are as follows.

Feasible exploration depth: 6mm

Measuring time: 40s

Heating power: 60mW

Sample temperature: 23 deg.C

TCR：0.004679K-1

Sensor type: dish

Sensor material type: kapton (R) Kapton (R) K)

Designing a sensor: 5465

Radius of the sensor: 3.189mm

After the input, the measurement is started. After the measurement is completed, the "calculate" button is selected, and the "start point: 10 "and" end point: 200", select the" standard analysis "button and calculate the" thermal conductivity "[ W/mK ].

< method for measuring softening Point of toner >

The softening point of the toner determined by the Flow Tester temperature raising method was measured under the following conditions according to an operating manual attached to the apparatus by using a Flow Tester CFT-500D (manufactured by Shimadzu Corporation).

In this apparatus, the measurement sample filled in the cylinder is heated and melted while a constant weight is applied from the top of the measurement sample using a piston, and the melted measurement sample is extruded from a die at the bottom of the cylinder. At this time, a flow curve showing the relationship between the piston depression amount and the temperature can be obtained.

In the present invention, the "melting temperature of 1/2 method" described in the manual attached hereto is regarded as the softening point. 1/2 the melting temperature of the method is calculated as follows.

First, 1/2 that is the difference between the piston-down amount Smax at the completion of outflow and the piston-down amount Smin at the start of outflow is determined (the difference 1/2 is regarded as X; X ═ Smax-Smin)/2). The temperature of the flow curve when the piston drop in the flow curve reaches X is the melting temperature of the 1/2 method.

Sample preparation: a sample was obtained by weighing 1.0g of the toner and molding by pressing with a press molding device having a diameter of 1cm under a load of 20kN for 1 minute

Diameter of die: 1.0mm

Length of the die: 1.0mm

Cylinder pressure: 9.807X 10⁵(Pa)

Measurement mode: method of raising temperature

Temperature rise rate: 4.0 deg.C/min

With the above method, the resulting piston drop amount (flow value) -temperature curve was plotted, and the softening point was measured as the temperature corresponding to h/2 (the temperature at which half of the resin had flowed out), where the height of the S-shaped curve was regarded as h.

Examples

Hereinafter, the present invention will be described in more detail with reference to production examples and embodiments, but the present invention is not limited thereto. All parts and percentages in the following formulations are on a mass basis unless otherwise specified.

< production of magnetic iron oxide 1>

An aqueous solution of a ferrous salt comprising ferrous hydroxide colloid was prepared by mixing 55L of a 4.0mol/L aqueous sodium hydroxide solution with 50L of a solution comprising 2.0mol/L Fe²⁺Mixing and stirring the ferrous sulfate aqueous solution. The resulting aqueous solution was maintained at 85 ℃ and an oxidation reaction was performed while blowing air at 20L/min, thereby obtaining a slurry including core particles.

The resulting slurry was filtered with a filter press and washed, and then the core particles were redispersed in water and reslurried. The magnetic iron oxide particles having a silicon-rich surface were obtained by adding sodium silicate to the repulped liquid at 0.20 mass% in terms of silicon per 100 parts of core particles, adjusting the pH of the slurry to 6.0, and stirring. The resulting slurry was filtered with a filter press, washed and then slurried again in ion-exchanged water. A total of 500g (10 mass% relative to the magnetic iron oxide) of an ion exchange resin SK110 (manufactured by Mitsubishi Chemical Corporation) was charged into the repulped liquid (solid content 50g/L), and ion exchange was carried out by stirring for 2 hours. Then, magnetic iron oxide 1 having a number average diameter of primary particles of 190nm was obtained by filtering and removing the ion exchange resin with a mesh screen, filtering and washing with a filter press, drying and pulverizing.

< production of magnetic iron oxides 2 and 3 >

Magnetic iron oxides 2 and 3 were obtained in the same manner as in the production of the magnetic iron oxide 1, except that the number average particle diameter of the magnetic iron oxide was adjusted in the production of the magnetic iron oxide 1. The physical properties of the obtained magnetic iron oxides 2 and 3 are shown in table 2.

< production of silane Compound 1>

A total of 30 parts of isobutyltrimethoxysilane was added dropwise to 70 parts of ion-exchanged water with stirring. The resulting aqueous solution was then kept at ph5.5 and a temperature of 55 ℃ and dispersed by using a dispersing blade at a peripheral speed of 0.46 m/sec for 120 minutes and hydrolyzed. The aqueous solution was then adjusted to ph7.0 and cooled to 10 ℃ to stop the hydrolysis reaction. Thus, the silane compound 1 was obtained as an aqueous solution including the hydrolyzate.

< production of silane Compounds 2 and 3 >

Silane compounds 2 and 3 were obtained in the same manner as silane compound 1 except that the type of silane compound in the production of silane compound 1 was changed as shown in table 1. The production conditions of the obtained silane compounds 2 and 3 are shown in table 1.

[ Table 1]

< production of magnetic body 1>

Magnetic iron oxide 1(100 parts) was put into a high-speed mixer (LFS-2, manufactured by Fukae Powtec Corporation), and silane compound 1(8.0 parts) was added dropwise over 2 minutes with stirring at a rotation speed of 2,000 rpm. Mixing and stirring was then carried out for 5 minutes. In order to increase the fixability of the silane compound 1, drying is then carried out at 40 ℃ for 1 hour, the amount of moisture is reduced, and the mixture is dried at 110 ℃ for 3 hours, advancing the condensation reaction of the silane compound 1. The magnetic body 1 was then obtained by grinding and sieving through a sieve having a mesh size of 100 μm.

< production of magnetic bodies 2 to 6 >

Magnetic bodies 2 to 6 were produced in the same manner as in the production of magnetic body 1 except that the magnetic iron oxide and the silane compound were changed to the magnetic iron oxide and the silane compound shown in table 2.

[ Table 2]

The surface silicon amount represents the amount (mass%) of silicon per 100 parts by mass of the magnetic iron oxide.

< production of crystalline polyester 1>

A total of 230.0 parts of sebacic acid as a carboxylic acid monomer and 242.1 parts of 1, 10-decanediol as an alcohol monomer were charged into a reaction tank equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple. The temperature was raised to 140 ℃ with stirring, heating to 140 ℃ was carried out under nitrogen atmosphere, and the reaction was carried out for 8h at normal pressure while distilling off water. Then, tin dioctoate was added in an amount of 1 part per 100 parts by mass of the total amount of the monomers, and then the reaction was carried out while raising the temperature to 200 ℃ at 10 ℃/h. The reaction was further carried out for 2 hours after the temperature of 200 ℃ was reached, then the pressure in the reaction tank was reduced to 5kPa or less, and the reaction was carried out at 200 ℃ for 3 hours, thereby obtaining a crystalline polyester 1. The crystalline polyester 1 thus obtained had a weight average molecular weight (Mw) of 20,100 and an acid value of 2.2 mgKOH/g.

< production of crystalline polyesters 2 to 8 >

Crystalline polyesters 2 to 8 were obtained in the same manner as in the production of the crystalline polyester 1 except that the alcohol monomer and the acid monomer were changed to those shown in table 3. The physical properties and structure of the crystalline polyester obtained are shown in table 3.

[ Table 3]

< production of toner particles 1>

The total of 450 parts of 0.1mol/L-Na₃PO₄The aqueous solution was poured into 720 parts of ion-exchanged water, followed by heating to 60 ℃. Then a total of 67.7 parts of 1.0mol/L-CaCl were added₂An aqueous solution to obtain an aqueous medium containing a dispersion stabilizer.

(amorphous saturated polyester resin obtained by condensation reaction of terephthalic acid with ethylene oxide (2mol) and propylene oxide (2mol) adducts of bisphenol A; Mw 9500, acid value 2.2mgKOH/g, and glass transition temperature 68 ℃ C.)

The above formulation was uniformly dispersed and mixed with a mill (Mitsui Miike Chemical Engineering Machinery Co., Ltd.), and a monomer composition was obtained. The monomer composition was heated to 63 ℃ and 10.0 parts of crystalline polyester 1 provided in Table 3 and 10.0 parts of behenyl sebacate (melting point Tm: 73.0 ℃) were added, mixed and dissolved.

The monomer composition was put into an aqueous medium and granulated by stirring with a TK-type homomixer (Tokushu Kika Kogyo co., Ltd.) at 60 ℃ for 10 minutes at 12,000rpm under a nitrogen atmosphere. Then, 9.0 parts of t-butyl peroxypivalate as a polymerization initiator was charged with stirring using a paddle type stirring blade, the suspension was heated to 70 ℃, and the reaction was carried out at 70 ℃ for 4 hours. After the reaction was complete, the suspension was heated to 100 ℃ and held for 120 minutes. Then, 5 ℃ water is put into the aqueous medium and cooled from 100 ℃ to 50 ℃ at a cooling rate of 50.0 ℃/min. The aqueous medium was then kept at 50 ℃ for 120 minutes and then allowed to cool naturally to 25 ℃ at room temperature. The cooling rate in this case was 1.0 ℃/min. Subsequent cooling, filtration and drying yielded toner particles 1. The formulation is shown in table 4.

< production of toner particles 2 to 24>

Toner particles 2 to 24 were produced in the same manner as in the production of toner particle 1 except that the type and part of magnetic body, the type and part of crystalline polyester, the type and part of ester wax, the part of crosslinking agent, and the cooling conditions were changed as shown in tables 4 and 5. The formulation is shown in table 4.

[ Table 4]

HNP-9: paraffin (Nippon Seiro Co., manufactured by Ltd.)

[ Table 5]

< production of toner 1>

Toner 1 toner particles 1(100 parts) were mixed with 0.3 part of hydrophobic silica and 0.1 part of alumina using an FM mixer (Nippon Coke)&Engineering co., Ltd.) was mixed. Hydrophobic silica has a specific surface area of 200m determined by the BET method²(ii)/g, and the surface thereof was hydrophobized with 3.0 mass% of hexamethyldisilazane and 3 mass% of 100-cps silicone oil. The alumina has a specific surface area of 50m as determined by the BET method²(ii) in terms of/g. The physical properties of toner 1 are shown in table 6.

< production of toners 2 to 24>

Toners 2 to 24 were produced in the same manner as in the production of toner 1 except that the toner particles were changed as shown in table 6. Physical properties are shown in Table 6.

[ Table 6]

< production of comparative toner particles 1>

The above starting materials were preliminarily mixed with a Mitsui Henschel mixer (manufactured by Mitsui Miike Chemical Engineering Machinery Co., Ltd.), and then kneaded with a twin-screw kneading extruder set at 200rpm and 130 ℃. The resulting mixture was rapidly cooled to room temperature. The coarse grinding was performed with a cutter mill, and the resulting coarse ground material was finely pulverized by using a turbine mill T-250 (manufactured by Turbo Kogyo co., ltd.) and adjusting the gas temperature in such a manner that the exhaust gas temperature was 50 ℃. Then, comparative toner particles 1 were obtained by classification using a multi-stage classifier utilizing the coanda effect.

< production of comparative toner particles 2 to 6 >

Comparative toner particles 2 to 6 were produced in the same manner as in the production of toner particle 1 except that the type and part of magnetic body, the type and part of crystalline polyester, the type and part of ester wax, the part of crosslinking agent, and the cooling conditions were changed as shown in table 7.

< production of comparative toners 1 to 6 >

Comparative toners 1 to 6 were produced in the same manner as in the production of toner 1 except that the toner particles were changed as shown in table 8. Physical properties are shown in Table 8.

[ Table 7]

< production of comparative toner 7>

(preparation of resin particle A) preparation of resin particle having three-layer Structure

A total of 8g of sodium lauryl sulfate was put into 3,000g of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introduction tube, and the internal temperature was raised to 80 ℃ while stirring at a stirring speed of 230rpm under a nitrogen stream. After the temperature was raised, a solution obtained by dissolving 10g of potassium persulfate in 200g of ion-exchanged water was added, the temperature was set to 80 ℃ again, the following liquid monomer mixture was dropwise added over 1 hour, and then polymerization was carried out by heating at 80 ℃ for 2 hours with stirring, thereby preparing resin particles. These particles are referred to as "resin particles (1H)".

A dispersion comprising emulsified particles (oil droplets) was prepared by: a solution obtained by dissolving sodium polyoxyethylene (2) lauryl ether sulfate in 800g of ion-exchanged water by 7g was put into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introduction tube, heated to 98 ℃, and then 260g of resin particles (1H) and a solution obtained by dissolving a monomer solution described below at 90 ℃ were added, and mixed and dispersed for 1H with a mechanical disperser "CLEARIX" (manufactured by M Technique Co., Ltd.) having a circulation path.

Then, a polymerization initiator solution prepared by dissolving 6g of potassium persulfate in 200g of ion-exchanged water was added to the dispersion, polymerization was carried out by heating and stirring the system at 82 ℃ for 1 hour, and resin particles were obtained. These particles are referred to as "resin particles (1 HM)".

A solution prepared by dissolving 11g of potassium persulfate in 400g of ion-exchanged water was further added, and a liquid mixture including the following monomers was added dropwise over 1 hour under a temperature condition of 82 ℃.

After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then the system was cooled to 28 ℃ to obtain resin particles. These particles are referred to as "resin particles A". The Tg of the resin particles A was 48 ℃ and the softening point was 88 ℃.

(preparation of resin particle B)

A total of 2.3g of sodium lauryl sulfate was put into 3,000g of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introduction tube, and the internal temperature was raised to 80 ℃ while stirring at a stirring speed of 230rpm under a nitrogen stream. After the temperature was raised, a solution obtained by dissolving 10g of potassium persulfate in 200g of ion-exchanged water was added, the liquid temperature was set to 80 ℃ again, the following liquid monomer mixture was dropwise added over 1 hour, and then polymerization was carried out by heating at 80 ℃ for 2 hours with stirring, thereby preparing resin particles. These particles are referred to as "resin particles B".

(preparation of colorant Dispersion)

A total of 90g of sodium lauryl sulfate was stirred and dissolved in 1,600g of ion-exchanged water. A total of 420g of carbon black was gradually added while stirring the solution. Then, a dispersion of the colorant particles was prepared by dispersing with a disperser "CLEARMIX" (manufactured by M Technique co., ltd.). This solution is referred to as a "colorant dispersion".

(agglutination and melt-adhesion step)

A total of 300g of resin particles a on a solids basis, 1,400g of ion-exchanged water, 120g of "colorant dispersion liquid" and a solution prepared by dissolving 3g of sodium polyoxyethylene (2) lauryl ether sulfate in 120g of ion-exchanged water were put into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen gas introduction device, and the liquid temperature was adjusted to 30 ℃. The pH was then adjusted to 10 by the addition of sodium hydroxide in 5N aqueous solution. Then, an aqueous solution prepared by dissolving 35g of magnesium chloride in 35g of ion-exchanged water was added under stirring at 30 ℃ over 10 minutes. After holding for 3 minutes, the temperature rise was started, the system temperature was raised to 90 ℃ over 60 minutes, and the particle growth reaction continued while holding the temperature at 90 ℃.

In this state, the diameter of the agglomerated particles was measured with a "Coulter Multisizer III" (manufactured by Beckman Coulter, Inc.), and when the median particle diameter based on the volume standard (D50) became 3.1. mu.m, 260g of the resin particles B were added and the particle growth reaction was further continued. When the desired particle size was reached, an aqueous solution obtained by dissolving 150g of sodium chloride in 600g of ion-exchanged water was added, thereby stopping the particle growth. Then, in the melt-adhering step, the melt-adhesion of the particles was advanced by heating and stirring at a liquid temperature of 98 ℃ until a circularity of 0.96 as measured by "FPIA-3000" (manufactured by Sysmex Corporation) was obtained. Then cooling to a liquid temperature of 30 ℃ was carried out, pH was adjusted to 4.0 by adding hydrochloric acid, and stirring was stopped.

(washing and drying step)

The particles prepared in the aggregation and melt-adhesion steps were subjected to solid-liquid separation using a basket centrifuge "MARKType-III, No.60 × 40" (Matsumoto Kikaki co., ltd., manufactured), and a wet cake of toner base particles was formed. The wet cake was washed with water in a basket centrifuge until the conductivity of the filtrate became 5. mu.S/cm, and then the cake was transferred to "Flash Jet Dryer" (manufactured by Seishin Enterprise Co., Ltd.) and dried to a moisture content of 0.5 mass%, thereby producing toner base particles having a median particle diameter (D50) of 6.2 μm on a volume basis.

(step of adding external additive)

A total of 1 mass% of hydrophobic silica (primary particle number average diameter of 12nm, degree of hydrophobicity of 68) and 0.3 mass% of hydrophobic titanium oxide (primary particle number average diameter of 20nm, degree of hydrophobicity of 63) were added to the obtained toner base particles and mixed with a Mitsui henschel mixer (Mitsui Miike Chemical Engineering Machinery co., ltd.) to prepare comparative toner 7. Physical properties of comparative toner 7 are shown in table 8.

[ Table 8]

< example 1>

A printer LBP3100 (manufactured by Canon inc.) was modified for printout evaluation. The modification involved increasing the process speed from the conventional process speed to 200 mm/sec and reducing the contact pressure of the fixing film and the pressure roller to 69kg · m/sec. The retrofit is also made in such a way that the fixing temperature of the fixing unit in the retrofit LBP3100 can be adjusted.

< evaluation of fixing >

The cold offset resistance in the above-described image forming apparatus was evaluated under a normal temperature and normal pressure environment (a temperature of 25.0 ℃ and a humidity of 50% RH). FOX RIVER BOND paper (110 g/m)²) For fusing media. By using a medium in the form of a thick paper having a relatively large surface unevenness, the fixing property under the conditions that promote peeling and rubbing can be strictly evaluated.

(Cold fouling resistance)

The toner carrying amount on the fixing medium was adjusted to 0.90mg/cm². Then, the fixing unit was cooled to room temperature (15 ℃), the solid image was printed 20 times in succession, the heater temperature of the fixing unit was randomly set in the range of 190 ℃ or higher and 250 ℃ or lower (hereinafter referred to as fixing temperature), and fixing was performed. Cold offset was visually determined in the 20 th printed image and evaluated according to the following measurement criteria.

A: no cold fouling at temperatures up to 200 ℃

B: cold offset at a temperature of 200 ℃ or more and less than 210 DEG C

C: cold offset at a temperature of 210 ℃ or more and less than 220 ℃

D: cold fouling at temperatures above 220 ℃

(Friction test)

The halftone image density is adjusted so that the image density on the fixing medium (measured using a Macbeth reflection densitometer (manufactured by Macbeth co.)) is 0.75 or more and 0.80 or less, and image formation is performed at a fixing temperature of 150 ℃.

Then, the fixed halftone image was applied with an application of 55g/cm²The loaded lens cleaning paper was rubbed 10 times. The density decrease rate at 150 ℃ was calculated from the halftone image densities before and after rubbing by using the following equation.

Density decrease rate (%) ([ (image density before friction) - (image density after friction) ]/(image density before friction) × 100

The density decreasing rate was similarly calculated by increasing the fixing temperature to 200 ℃ at 5 ℃. The temperature at which the density decrease rate becomes 15% is calculated from the evaluation results of the fixing temperature and the density decrease rate obtained through a series of operations, and the calculated temperature is regarded as a fixing lower limit temperature indicating a threshold value at which the low-temperature fixing performance is satisfactory.

A: the lower limit temperature of fixation is less than 160 DEG C

B: the lower limit temperature of fixation is more than 160 ℃ and less than 170 DEG C

C: the lower limit temperature of fixation is more than 170 ℃ and less than 180 DEG C

D: the lower limit temperature of fixing is above 180 DEG C

(resistance to Heat fouling)

In the evaluation of the hot offset resistance, halftone images having a height of 2.0cm and a width of 15.0cm were formed at 90g/m in a portion 2.0cm from the upper end portion and a portion 2.0cm from the lower end portion with respect to the sheet passing direction under a normal temperature and pressure environment (a temperature of 25 ℃ and a humidity of 50% RH)²A4 size paper. At the time of image formation, the image density measured using a Macbeth reflection densitometer (manufactured by Macbeth co.) is adjusted to 0.75 or more and 0.80 or less. Image formation was performed by raising the set temperature of the fixing unit from 170 ℃ at 5 ℃. Evaluation was performed visually according to the following measurement standards.

A: no hot fouling at temperatures up to 200 deg.C

B: hot offset at a temperature of 190 ℃ or higher and less than 200 ℃

C: hot offset at a temperature of 180 ℃ or higher and less than 190 ℃

D: hot offset at temperatures below 180 ℃

< evaluation of storage stability >

(evaluation of Long-term storage Property)

A total of 10g of toner 1 was put into a 100mL glass bottle, allowed to stand at a temperature of 45 ℃ and a humidity of 95% for 3 months, and visually evaluated.

A: is not changed

B: form aggregates, but immediately loosen

C: form aggregates which are not easily loosened

D: has no fluidity

E: clearly, caking appeared

< examples 2 to 24>

Evaluation was performed in the same manner as in example 1 except that toners 2 to 24 were used. The evaluation results are shown in table 9.

< comparative examples 1 to 7>

Evaluation was performed in the same manner as in example 1 except that comparative toners 1 to 7 were used. The evaluation results are shown in table 9.

[ Table 9]

Claims (4)

1. A toner comprising toner particles containing a binder resin, a wax, and a colorant, wherein:

the softening point of the toner is 80 ℃ or higher and 140 ℃ or lower;

the average circularity of the toner is 0.940 or more;

an integrated value of stress of the toner at 150 ℃ when measured using a viscosity tester on a toner pellet obtained by compressing the toner is 78g · m/sec or more;

the toner particles further include a crystalline polyester;

the crystalline polyester has a partial structure represented by the following formula (1):

formula (1)

Wherein m is an integer from 4 to 14; n is an integer from 6 to 16;

the binder resin is styrene-acrylic resin;

the wax comprises an ester wax;

the ester wax is an ester compound of a dihydric alcohol and an aliphatic monocarboxylic acid, or an ester compound of a dihydric carboxylic acid and an aliphatic monohydric alcohol.

2. The toner according to claim 1, wherein the colorant is a magnetic body.

3. The toner according to claim 1, wherein the thermal conductivity of the toner is 0.190W/mK or more and 0.300W/mK or less.

4. The toner according to claim 1, wherein an average circularity of the toner is 0.950 or more.

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