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(11) | EP 0 582 281 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Toner compositions for electrostatic developers |
| (57) Toner compositions for electrostatic copiers containing siloxane resins with difunctional
and trifunctional siloxane units as charge regulating agents are releasable, and have
very stable charging properties with respect to temperature and humidity. When the
siloxane units of the resin contain amino-functional hydrocarbon radicals or haloalkyl
radicals the presence of prior art charging regulators is not required. |
BACKGROUND OF THE INVENTION
[0001] The present invention relates to toner compositions for electrostatic developing. More particularly, this invention relates to toner compositions with good release properties, and with charging characteristics that are very stable with respect to temperature and humidity.
[0002] Toner compositions for electrostatic developing (ED) processes typically contain at least one thermoplastic resin and a colorant as principal ingredients together with various optional additives, for example, charging regulators, fluidizers, fillers, cleaners, and so forth. The homogeneity, charging properties, fluidity, fusing characteristics, and other properties of these ED toner can be regulated or adjusted through the particular combination of these ingredients.
[0003] One problem with prior art ED toners is the variation of their charging properties with temperature and humidity. These toners do not release well from hot-fixing rolls, and as a result stain the surface of such rolls. In addition, the heavy metal-based organometallic compounds heretofore used as charging regulators are colored and toxic. As a consequence, the resulting ED toner is toxic to humans and contaminates the environment, and, in the case of color copiers, suffers from a degraded color tone.
[0004] One objective of the present invention is to provide a releasable ED toner whose charging properties are very stable with respect to temperature and humidity. A second objective of this invention is the introduction of a releasable ED toner containing a white charging regulator comprising an organosiloxane resin.
DETAILED DESCRIPTION OF THE INVENTION
[0005] The present invention provides a toner composition for an electrostatic developer, said composition comprising an organic resin, a pigment, and a charging regulator comprising an organosiloxane resin having a general formula selected from the group consisting of (R¹SiO3/2)m(R¹₂SiO)n, (R²SiO3/2)m(R²₂SiO)n and (R³SiO3/2)m(R³₂SiO)n where R¹ represents a monovalent hydrocarbon radical, each R² is individually selected from the group consisting of monovalent hydrocarbon radicals and aminoalkyl radicals, where at least a portion of the R² substituents are aminoalkyl radicals, each R³ is individually selected from the group consisting of monovalent hydrocarbon radicals and haloalkyl radicals, with the proviso that at least a portion of the R³ substituents are haloalkyl radicals, m and n are both positive numbers and provide a softening point for said organosiloxane resin greater than 25⁰ C and not greater than 200°C.
[0007] One type of resin contains unsubstituted hydrocarbon radicals and can be represented by the general formula I.
I (R¹SiO3/2)m(R¹₂SiO)n
R¹ and R² in this formula represent identical or different monovalent hydrocarbon radicals. Hydrocarbon radicals that can be represented by R¹ and R² contain from 1 to about 20 carbon atoms, and include but are not limited to alkyl radicals such as methyl, ethyl, propyl, butyl, pentyl and hexyl;
cycloalkyl radicals such as cyclopentyl, cyclohexyl and cycloheptyl; alkenyl radicals such as vinyl, allyl, butenyl and hexenyl; aryl radicals such as phenyl, tolyl, and xylyl; and aralkyl groups such as benzyl, phenethyl and phenylpropyl.
[0008] The subscripts m and n are positive numbers and provide a molecular weight such that the resin softens above room temperature, typically 25° C. but no higher than 200⁰ C. The softening points of preferred resins do not exceed 150°C.
[0009] This restriction on the softening point of the organosiloxane resin makes possible the uniform dispersion of the organosiloxane resin in the thermoplastic organic resin through the softening and melting of both types of resins during preparation of the present ED toner compositions. The organic resin constitutes the major ingredient of the present toner compositions and is described in a subsequent section of this specification.
[0010] The softening temperature of the organosiloxane resin is least room temperature, typically 25⁰ C, in order to prevent bleed-out of the organosiloxane resin from the ED toner composition. When the ED toner of the present invention contains an organosiloxane resin with repeating units corresponding to formula I, the charging characteristics of the resin will be very stable with respect to temperature and humidity and the ED toner itself will be highly releasing.
[0011] A second type of organosiloxane resin suitable for use in the present ED toner compositions corresponds to general
formula II.
II (R²SiO3/2)m(R²₂SiO)n
Each R² in formula II is selected from the group consisting of unsubstituted monovalent hydrocarbon radicals and aminoalkyl radicals, with the proviso that at least a portion of the groups represented by R² are aminoalkyl radicals.
[0012] The unsubstituted hydrocarbon radicals represented by R² are selected from the same group defined for R¹ in formula I. When R² represents an aminoalkyl radical, suitable radicals include but are not limited to primary aminoalkyl radicals such as aminoethyl, aminopropyl and aminobutyl; secondary aminoalkyl groups such as N-methylaminopropyl, N-ethylaminopropyl, 8-phenyl-4,7-diazaoctyl and 4,7-diazapentadecyl; combinations of primary and secondary aminoalkyl groups such as N-(2-aminoethyl)-3-aminopropyl and N-(3-aminopropyl)-3-aminopropyl; the salts of primary aminoalkyl groups such as the hydrochloride of the aminoethyl group, the hydrobromide of the aminoethyl group, the hydrochloride of the aminopropyl group, and the hydrochloride of the aminobutyl group; the salts of secondary aminoalkyl groups such as the hydrochloride of the N-methylaminopropyl group, the hydrochloride of the N-ethylaminopropyl group, the hydrochloride of the 8-phenyl-4,7-diazaoctyl group, and the hydrobromide of the 4,7-diazapentadecyl group; tertiary aminoalkyl groups such as N,N-dimethylaminopropyl and N,N-methylethylaminopropyl; the hydrochloride of the N,N-dimethylaminopropyl group; and quaternary aminoalkyl groups.
[0013] The subscript m and n are described in connection with formula I, and are selected to achieve the desired softening point for the organosiloxane resin. When the ED toner of the present invention contains an organopolysiloxane resin with repeating units corresponding to formula II, the charging characteristics of the toner will be very stable with respect to temperature and humidity and the toner will be highly releasing. In addition, because this organosiloxane resin also contains aminoalkyl radicals, it can be used as a charging regulator that will control or regulate the polarity of the ED toner to a high positive polarity. In addition, because this organopolysiloxane resin is translucent or white, it will not adversely affect toner color in the case of ED toner for color copiers.
[0014] A third class of organosiloxane resins suitable for use in the present ED toner compositions has the general formula represented by formula III.
III (R³SiO3/2)m(R³₂SiO)n
R³ in formula III is selected from the group consisting of monovalent hydrocarbon radicals and haloalkyl radicals, with the proviso that at least a portion of the are haloalkyl radicals.
[0015] The monovalent hydrocarbon radicals represented by R³ are selected from the same class as the hydrocarbon radicals represented by R1 in formula I, discussed in a preceding section of this specification.
[0016] The haloalkyl radicals represented by R³ include but are not limited to chloromethyl, bromomethyl, chloroethyl, chloropropyl, chlorobutyl, 3,3,3-trifluoropropyl, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl, and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl.
[0018] When the ED toner composition contains an organopolysiloxane corresponding to formula III, its charging characteristics will be very stable with respect to temperature and humidity and the ED toner itself will be highly releasing. In addition, because this organosiloxane resin also contains haloalkyl radicals, it can be used as a charging regulator that will control or regulate the polarity of the ED toner to a high negative polarity.
[0019] In addition, because this organosiloxane resin is translucent or white, it will not adversely affect toner color in the case of ED toner for color copiers.
[0020] The thermoplastic organic resin is the principal ingredient of the present ED toner compositions. The type of resin selected for this ingredient is not specifically restricted, and any thermoplastic resin typically used for prior art ED toner compositions can be employed in the present.
[0021] The organic resin can be a natural or synthetic resin. Examples of suitable thermoplastic organic resins include but are not limited to polystyrene resins, alpha-methylstyrene resins, chlorostyrene resins, styrene/acrylic copolymers, styrene/butadiene copolymers, styrene/butyl methacrylate copolymers, styrene/divinylbenzene/butyl acrylate copolymers, styrene/maleic acid copolymers, acrylic resins, methacrylic resins, ethyl methacrylate resins, butadiene resins, isoprene resins, acrylonitrile resins, vinyl ether resins, vinyl acetate resins, polycarbonate resins, polyurethane resins, fluororesins, polyester resins, epoxy resins, polyamide resins, and natural and synthetic waxes.
[0022] The softening point of the thermoplastic resin is not specifically restricted, but preferably does not exceed 200°C. The proportion of thermoplastic organic resin in ED toner of the present invention is not specifically restricted, but preferably constitutes from 80 to 90 weight percent of the in the ED toner composition.
[0023] A pigment or other colorant is a required ingredient of the present toner compositions. This ingredient determines the color of the composition, and its type is not specifically limited. Suitable pigments and colorants include but are not limited to black pigments such as carbon black, oil black, and graphite; organic dyes such as Quinoline Yellow, Phthalocyanine Blue, and Malachite Green oxalate; acetoacetic arylamide-type monoazo yellow pigments such as C.I. Pigment Yellow 1, C.I. Pigment Yellow 3, C.I. Pigment Yellow 74, C.I. Pigment Yellow 97, and C.I. Pigment Yellow 98; acetoacetic arylamide-type diazo yellow pigments such as C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. and Pigment Yellow 14; yellow dyes such as C.I. Solvent Yellow 19, C.I. Solvent Yellow 77, C.I. Solvent Yellow 79, C.I. and Disperse Yellow 164; red or magenta pigments such as C.I. Pigment Red 48, C.I. Pigment Red 49:1, C.I. Pigment Red 53:1, C.I. Pigment Red 57:1, C.I. Pigment Red 81, C.I. Pigment Red 122, and C.I. Pigment Red 5; red dyes such as C.I. Solvent Red 52, C.I. Solvent Red 58, and C.I. Solvent Red 8; blue dyes and pigments such as C.I. Pigment Blue 15:3 and copper phthalocyanine and its derivatives and modified products; green pigments such as C.I. Pigment Green 7, and C.I. Pigment Green 36; and colored and leuco sublimable dyes. While the proportion of colorant in the ED toner of the present invention is not specifically restricted, the present ED toner compositions preferably contain a total of from 1 to 20 weight% of one or more colorants.
[0024] In addition to the resins and colorants ingredients described in the preceding sections of this specification, the present ED toner compositions may optionally contain charging regulators other than the present organosiloxane resins, fluidizers, fillers, and cleaners. These optional ingredients will be described in greater detail in the following section of this specification.
[0025] Charging regulators other than the organosiloxane resins described in a preceding section of this specification can be present as an optional ingredient whose purpose is to further control or regulate the type and amount of charge on the ED toner particles. The type of optional charge regulator is not specifically limited. Suitable classes of optional charging regulators include but are not limited to chromium complexes of azo dyes, chromium complexes of aromatic hydroxycarboxylic acids, the aluminum complexes of aromatic hydroxycarboxylic acids and aromatic carboxylic acids, zinc complexes of aromatic hydroxycarboxylic acids and aromatic carboxylic acids, and boron complexes of aromatic hydroxycarboxylic acids and aromatic carboxylic acids.
[0026] An optional charge regulator is preferably included when the hydrocarbon radicals of the charge-regulating organosiloxane resin contain only unsubstituted hydrocarbon radicals, corresponding to formula I in the preceding section of this specification.
[0027] When general formula of the organosiloxane resin corresponds to either formula II or III the presence of additional charge regulators is optional.
I (R¹SiO3/2)m(R¹₂SiO)n
II (R²SiO3/2)m(R²₂SiO)n
III (R³SiO3/2)m(R³₂SiO)n
The concentration of optional charge regulator is not specifically limited, however a range of from 1 to 5 weight percent, based on the total weight of the toner composition is preferred.
[0028] Fluidizers are optional ingredients whose purpose is to improve the flowability of the ED toner, and there are no specific limitations regarding the type of fluidizer. Suitable fluidizers include but are not limited to colloidal silica, metal soaps, and nonionic surfactants. The concentration of proportion of fluidizer in the ED toner composition is not specifically restricted, but is preferably from 0.1 to 2 weight percent, based on the total weight of the toner composition.
[0029] When the present compositions contain a filler, suitable ones include but are not limited to silica, alumina, titanium dioxide, barium titanate, zinc oxide, quartz sand, iron oxide, ferrite, calcium carbonate, clay, and talc. The concentration of filler is not specifically restricted, but preferably constitutes from 1 to 5 weight percent, based on the total weight of the toner composition.
[0030] Suitable cleaners that can be present include but are not limited to metal salts of fatty acids, fluorine surfactants, and silicon oxide derivatives. The concentration of cleaner is not specifically restricted, but preferably constitutes from 0.1 to 1 weight percent of the present compositions.
[0031] The present ED toner compositions can be prepared by mixing the various components and optional components as described hereinbefore to homogeneity. The method for preparing the ED toner is not specifically restricted, and can use conventional manufacturing equipment. Suitable equipment includes but is not limited to Ross mixers, kneader mixers, ball mills, and Henschel mixers.
[0032] The temperature to which the composition is heated during preparation must be at least to the softening points of the thermoplastic and organopolysiloxane resins used to prepare the composition.
[0033] The charging properties of the ED toner compositions of the present invention are very stable with respect to temperature and humidity due to the presence of the organosiloxane resin. This stability allows the toner compositions to be used in electrostatic copiers that are operated in harsh environments. Moreover, because the ED toner of the present invention is releasing, it makes possible a substantial simplification of the roll cleaning mechanism, such as by allowing for the elimination of fuser oil for fixing rolls.
[0034] When the organosiloxane resin ingredient of the present toner compositions contains the aminoalkyl radicals represented by R2 in formula II, the organosiloxane resin can function as a white charging regulator. As a result, the composition of the ED toner can be simplified by the elimination of prior art non-silicone type charging regulators described in a preceding section of this specification unnecessary. Moreover, the organosiloxane resin corresponding to formula II can be used as a charging regulator for ED toner for various types of color copiers. In this application it is less toxic to humans and less environmentally burdensome than the heretofore known ED toners.
[0035] The following examples describe preferred embodiments of the present ED toner compositions and should not be interpreted as limiting the scope of the invention defined in the accompanying claims. Unless otherwise specified in the examples all parts and percentages are by weight and measurements were conducted at 25⁰ C.
[0036] To measure peel force, a thin layer of the ED toner composition was applied to a 6 mm-thick silicone rubber intended for use on the hot pressure-fixing rolls of a copier. The composition was then heated to bond it to the surface of the sheet. A commercial pressure-sensitive adhesive tape (width = 1.8 cm) was applied over the bonded layer, and high-speed peel test was then carried out by peeling the tape from the sheet using an angle of 180° and a peel rate of 100 m/minute.
Reference Example 1
[0037] 100 g water, 100 g isopropyl alcohol, and 400 g toluene were introduced into a 2 L round-bottom flask equipped with a stirrer, thermometer, and addition funnel. A liquid mixture containing 297 g (approximately 1.4 moles) phenyltrichlorosilane, 76 g (approximately 0.3 moles) diphenyldichlorosilane, and 39 g (approximately 0.3 moles) dimethyldichlorosilane was then added dropwise to the liquid in the reactor over a 1 hour period while stirring the reaction mixture. Following completion of this addition, the reaction mixture was heated at the boiling point for 2 hours and then cooled. The stirrer was stopped, the contents of the flask were allowed to settle, and the lower layer was drawn off. 600 g 10 weight% aqueous sodium bicarbonate was introduced followed by stirring for 30 minutes and then quiescence. The lower layer was again drawn off. The pH was determined to be 10.
[0038] The following process was then repeated twice: addition of 600 g water, stirring for 30 minutes, settling of the reaction mixture, and removal of the lower toluene-containing layer. The resulting toluene solution was heated at 150°C/30 torr in order to remove the toluene and distillates. The residue was transferred to a metal vat to yield a thick liquid at 150°C. After cooling to room temperature, the resultant solid was ground in a mortar to yield a white microparticulate organopolysiloxane resin.
[0039] This organosiloxane resin had a softening point of 95°C and the following structural formula.
(C₆H₅SiO3/2)₇O[(C₆H₅)₂SiO]₁₅[(CH₃)₂SiO]₁₅
Reference Example 2
[0040] 100 g water, 100 g isopropyl alcohol, and 400 g toluene were introduced into a 2 L round-bottom flask equipped with a stirrer, thermometer, and addition funnel. A liquid mixture containing 297 g (approximately 1.4 moles) phenyltrichlorosilane, 76 g (approximately 0.3 moles) diphenyldichlorosilane, and 39 g (approximately 0.3 moles) dimethyldichlorosilane was then added dropwise over 1 hour with stirring. Following completion of this addition, the reaction solution was heated under reflux for 2 hours and then cooled. The stirrer was then stopped, the contents of the flask were allowed to settle, and the lower layer was drawn off. 600 g 10 weight% aqueous sodium bicarbonate were added, followed by stirring for 30 minutes and then quiescence. The lower layer was again drawn off, and the pH was measured as 10.
[0041] The following process was then repeated twice: addition of 600 g water, stirring for 30 minutes, settling, and removal of the lower layer. Using an evaporator to distill the toluene and water from the resulting toluene solution, a toluene solution was prepared that contained 50% volatile fraction at 150°C. This toluene solution of organopolysiloxane resin had a viscosity of 6 centipoise at 25°C.
[0042] 25 g N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane was then introduced into 500 g of the organopolysiloxane resin solution prepared above. After heating the reaction mixture for 5 hours at the reflux temperature, the reaction mixture was heated to 150°C and the toluene and distillates were removed at 30 torr. Removal of the residue to a metal vat yielded a thick liquid at 150°C. The contents of the vat were allowed to cool to room temperature, and the resultant solid was ground in a mortar to yield a white finely divided resin containing N-(2-aminoethyl)-3-aminopropyl-methylsiloxane units. The resultant organosiloxane resin had a softening point of 80°C and the following structural formula.
(C₆H₅SiO3/2)₇₀[(C₆H₅)₂SiO]₁₅[(CH₃)₂SiO]₁₅-
[H₂NC₂H₄NHC₃H₆(CH₃)SiO]₁₂
Reference Example 3
[0043] 525 g toluene, 525 g of the final resin described in Reference Example 2, and 15.7 g benzyl chloride were placed in a 1 L round-bottom flask equipped with stirrer, thermometer, and addition funnel and heated at the reflux temperature of toluene for 2 hours. When this reaction mixture was analyzed by silver nitrate titration, the chlorine concentration was 0.7 weight%, which was 94.6 percent of the theoretical value. The toluene and distillates were then removed by heating the reaction mixture at 150°C/30 torr. Removal of the residue to a metal vat afforded a thick liquid at 150°C. This liquid was poured out and allowed to cool. The resultant solid was ground using a mortar to yield the hydrochloride of an organosiloxane resin containing 8-phenyl-4,7-diazaoctyl radicals bonded to silicon. The resin was in the form of a very slightly yellow finely divided powder. This resin had a softening point of 75°C to 85°C and the following structural formula.
[(C₆H₅SiO3/2)₇₀{(C₆H₅)₂SiO}₁₅{(CH₃)₂SiO}₁₅-
{C₆H₅CH₂NHC₂H₄NHC₃H₆(CH₃)SiO}₁₂].HCl
Reference Example 4
[0044] 525 g toluene, 525 g of the N-(2-aminoethyl)-3-aminopropyl-containing organosiloxane resin prepared in Reference Example 2, and 24.0 g octyl bromide were placed in a 1 L round-bottom flask equipped with stirrer, thermometer, and addition funnel and heated at the reflux temperature of toluene for 2 hours. When this reaction mixture was analyzed by silver nitrate titration, the bromine concentration was 0.8 weight%, which was 90.6 percent of the theoretical value.
[0045] The toluene and distillates were then removed by heating the reaction mixture at 150°C/30 torr. Removal of the residue to a metal vat afforded a thick liquid at 150°C. After cooling to room temperature, the resultant solid was ground with a mortar to yield the hydrobromide of a 4,7-diazapentadecyl- containing organosiloxane resin in the form of a very slightly yellow finely divided powder. This resin had a softening point of 75°C to 85°C and the structural formula.
[(C₆H₅SiO3/2)₇₀{(C₆H₅)₂SiO}₁₅{(CH₃)₂SiO}₁₅-
{C₈H₁₇NHC₂H₄NHC₃H₆(CH₃)SiO}₁₂].HBr
Reference Example 5
[0046] 100 g water, 100 g isopropyl alcohol, and 400 g toluene were introduced into a 2 L round-bottom flask equipped with a stirrer, thermometer, and addition funnel. The liquid mixture of 297 g (approximately 1.4 moles) phenyltrichlorosilane, 76 g (approximately 0.3 moles) diphenyldichlorosilane, and 39 g (approximately 0.3 moles) dimethyldichlorosilane was then added dropwise over 1 hour while stirring the reaction mixture. Following completion of this addition, the reaction mixture was heated under reflux for 2 hours and then cooled. The stirrer was stopped and the contents of the flask allowed to settle, at which time the lower layer was drawn off. 600 g of a 10 weight% aqueous sodium bicarbonate was introduced followed by stirring for 30 minutes. When the reaction mixture had settled the lower layer was again drawn off. The pH was measured as 10.
[0047] The following process was then repeated twice: addition of 600 g water, stirring for 30 minutes, settling, and removal of the lower layer. Using an evaporator to distill the toluene and water from the resulting toluene solution, sufficient toluene was removed at 150⁰ C to obtain a solution containing 50% of volatile fraction. This solution had a viscosity of 6 centipoise. 25 g of 3-chloropropylmethyldimethoxysilane was then introduced into 500 g of this solution, followed by heating at the reflux temperature for 5 hours.
[0048] The reaction mixture was then heated at 150°C/30 torr in order to remove the toluene and distillates. The resultant thick liquid was transferred at a temperature of 150⁰ C removed to a metal vat for cooling. After cooling to room temperature, the resultant solid as ground using a mortar to yield a white microparticulate organosiloxane resin. This organopolysiloxane resin had a softening point of 80°C and the structural formula
(C₆H₅SiO3/2)₇₀[(C₆H₅)₂SiO]₁₅[(CH₃)₂SiO]₁₅-
[ClC₃H₆(CH₃)SiO]₁₃ .
Example 1
[0049] An ED toner composition of this invention exhibiting an average particle diameter of micrometers was prepared by melt-mixing a blend of the following ingredients in a kneader mixer for 3 hours while heating and then grinding and classifying:
| styrene/acrylic copolymer (softening point = 150°C) | 100 weight parts |
| organosiloxane resin from Reference Example 1 | 5 weight parts |
| carbon black (#40) | 5 weight parts. |
[0050] The resulting ED toner composition had a good flowability. The ED toner was also subjected to surface analysis for the silicon atom using a scanning electron microscope equipped with an X-ray microanalyzer, referred to hereinafter as SEM-XMA. The results demonstrated an extremely homogeneous dispersion of silicon.
[0051] The charge retention ability of the toner particles was determined using a "blow-off" test. The test was conducted by shaking for 10 minutes a mixture containing 1.5 parts of the toner particles and 30 parts of iron powder with an average particle size of 300 micrometers. The resultant mixture was placed on a stainless steel filter in a Faraday cage and a stream of nitrogen was blown through the filter for 30 seconds. The toner particlesw were forced through the holes in the filter under the pressure of the gas, leaving behind the iron particles with a charge of equal magnitude and opposite in polarity to the charge on the toner particles. This charge is then transferred to a capacitor in the Faraday cage curcuit and the resultant charge (C) and voltage (V) are measured. The charge to mass ratio for the tomer particles can be calculated using the formula
, where M is the weight of the toner particles present in the initial mixture.
[0052] In order to determine the effects of temperature and humidity, the charged toner particles were spread on a glass petri dish and allowed to stand for 24 hours at 60°C/RH 95%, at which time the charge was measured again.
[0053] The releasability of the toner particles from a fuser roll maintained at a temperature of 150⁰ C was also measured. The results of all evaluations are reported in Table 1.
Example 2
[0054] An ED toner composition with an average particle diameter of 15 micrometers was prepared by melt-mixing a blend of the following ingredients in a kneader mixer for 3 hours while heating and then grinding and classifying:
| styrene/acrylic copolymer (softening point = 150°C) | 100 weight parts |
| organopolysiloxane resin containing the N-(2-aminoethyl)-3-aminopropyl group, from Reference Example 2 | 5 weight parts |
| carbon black (#40) | 5 weight parts. |
[0055] The resultant ED toner composition had a good flowability. The ED toner was also subjected to surface analysis for the Si atom using SEM-XMA. These results demonstrated an extremely homogeneous dispersion of the Si.
[0056] 1.5 weight parts of the ED toner was shaken for 10 minutes in a shaker with 30 weight parts iron powder with average particle size of 300 micrometers. The charge retention ability of the toner particles was measured using the "blow-off" test described in Example 1. In order to examine the effects of temperature and humidity, the charged toner particles were spread on a glass petri dish and allowed to stand for 24 hours at 60°C/RH 95%, at which time the charge was again measured again. The releasability of the ED toner was also measured as described in Example 1. These results are reported in Table 1.
Example 3
[0057] An ED toner composition of this invention with an average particle diameter of 15 micrometers was prepared by melt-mixing a composition of the following components in a kneader mixer for 3 hours while heating and then grinding and classifying:
| styrene/acrylic copolymer (softening point = 150°C) | 100 weight parts |
| organopolysiloxane resin containing the 8-phenyl-4,7-diazaoctyl group, from Reference Example 3 | 5 weight parts |
| carbon black (#40) | 5 weight parts. |
[0058] The resulting ED toner composition had a good flowability. The ED toner was also subjected to surface analysis for the Si atom using SEM-XMA. These results demonstrated an extremely homogeneous dispersion of the Si.
[0059] The "blow-off" test described in Example 1 was conducted using 1.5 weight parts of the ED toner and 30 weight parts iron powder (average particle size = 300 micrometers). In order to examine the effects of temperature and humidity, the charged toner particles were spread on a glass petri dish and allowed to stand for 24 hours at 60°C/RH 95% and the charge was then measured again. The releasability of the ED toner was also measured as described in Example 1. These results are reported in Table 1.
Example 4
[0060] An ED toner composition with an average particle diameter of 15 micrometers was prepared by melt-mixing a blend of the following ingredients in a kneader mixer for 3 hours while heating and then grinding and classifying:
| styrene/acrylic copolymer (softening point, 150°C) | 100 weight parts |
| organopolysiloxane resin containing the 4,7-diazapentadecyl group, from Reference Example 4 | 5 weight parts |
| carbon black (#40) | 5 weight parts. |
[0061] The resulting ED toner had a good flowability. The toner was also subjected to surface analysis for the Si atom using SEM-XMA. These results demonstrated an extremely homogeneous dispersion of the Si.
[0062] The charge retention characteristics of the toner was determined using the "blow-off" test described in Example 1. In order to examine the effects of temperature and humidity, the ED toner, after charging as above, was spread in a glass petri dish and allowed to stand for 24 hours at 60°C/RH 95% and the charge was then measured again.
[0063] The releasability of the ED toner was also measured as described in Example 1. These results are reported in Table 1.
Example 5
[0064] An ED toner composition of this invention with an average particle diameter of 15 micrometers was prepared by melt-mixing a blend of the following ingredients in a kneader mixer for 3 hours while heating and then grinding and classifying:
| styrene/acrylic copolymer (softening point, 150°C) | 100 weight parts |
| organopolysiloxane resin containing the 3-chloropropyl group, from Reference Example 5 | 5 weight parts |
| carbon black (#40) | 5 weight parts. |
[0065] The resultant ED toner composition had good flowability. The toner composition was also subjected to surface analysis for the Si atom using SEM-XMA. These results demonstrated an extremely homogeneous dispersion of Si atoms.
[0066] The charge retention characteristics of the toner was determined using the "bloww-off" test described in Example 1. To determine the effects of temperature and humidity on charge retention, the charged toner particles were spread on a glass petri dish and allowed to stand for 24 hours at 60°C/RH 95%, at which time the charge was then measured again.
[0067] The releasability of the ED toner was also measured as described in Example 1. The results of all the testing are reported in Table 1.
Comparison Example 1
[0068] For comparative purposes an ED toner composition outside the scope of the present invention was prepared as described in Example 1 of this specification, with the exception that a commercial azine charging regulator was used in place of the organosiloxane resin used in Example 1. The resulting ED toner was evaluated as described in Example 1, and these results are reported in Table 1.
Comparison Example 2
[0069] ED toner outside the scope of the present invention was prepared using the procedure and ingredients described in Comparison Example 1, but with the addition of 0.5 weight parts of a liquid polydimethylsiloxane with a viscosity of 500 centistokes. The resultant ED toner composition was evaluated as described in Example 1, and the results are reported in Table 1.
Table 1
| Example | Dispersability | Charge (microcoulombs/g) | Peel Force (g/cm) | |
| Initially | After 24 hr at 60⁰C | |||
| 1 | excellent | 13 | 12 | 20 |
| 2 | excellent | 27 | 25 | 23 |
| 3 | excellent | 31 | 28 | 32 |
| 4 | excellent | 29 | 24 | 34 |
| 5 | excellent | -15 | -11 | 37 |
| Comparison Example 1 | - | 25 | 11 | 123 |
| Comparison Example 2 | poor (oil bleed occurred) | 24 | 14 | 16 |
1. A toner composition for an electrostatic developer comprising an organic resin, a
colorant, and a charging regulator comprising an organosiloxane resin having a general
formula selected from the group consisting of (R¹SiO3/2)m(R¹₂SiO)n. (R²SiO3/2)m(R²₂SiO)n and (R³SiO3/2)m(R³₂SiO)n where R¹ represents a monovalent hydrocarbon radical, each R² is individually selected
from the group consisting of monovalent hydrocarbon radicals and aminoalkyl radicals,
where at least a portion of the R² substituents are aminoalkyl radicals, each R³ is
individually selected from the group consisting of monovalent hydrocarbon radicals
and haloalkyl radicals, with the proviso that at least a portion of the R³ substituents
are haloalkyl radicals, m and n are both positive numbers and provide a softening point for said organosiloxane resin
greater than 25⁰ C and not greater than 200°C.
2. A composition according to claim 1 where R¹SiO3/2, R²SiO3/2 and R³SiO3/2 are methylsiloxy or phenylsiloxy; R¹₂SiO is a combination of diphenylsiloxane and
dimethylsiloxane, R²₂SiO is a combination of diphenylsiloxane, dimethylsiloxane, and
R⁴(H)NCH₂CH₂N(H)(CH₂)₃Si(CH₃)O-, where R⁴ is hydrogen, octyl or benzyl, and R³₂SiO
is a combination of diphenylsiloxane, dimethylsiloxane and 3-chloropropylmethylsiloxane,
and said organic resin is a homopolymer or copolymer dervied from styrene.
3. A composition according to claim 2 where the softening point of said organosiloxane
resin does not exceed 150⁰ C, the softening point of said organic resin does not exceed
200⁰ C and said organic resin constitutes from 80 to 90 percent of the total weight
of said composition.