Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/097—Plasticisers; Charge controlling agents
  • G03G9/09733—Organic compounds
  • G03G9/09775—Organic compounds containing atoms other than carbon, hydrogen or oxygen
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08742—Binders for toner particles comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • G03G9/08755—Polyesters
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08775—Natural macromolecular compounds or derivatives thereof
  • G03G9/08782—Waxes

Definitions

• the present invention relates to a toner for developing an electrostatic latent image formed in electrophotography, electrostatic recording, electrostatic printint, etc.
• Development process of electrostatic latent images generally comprises a step in which an electrostatically charged fine toner particles are attracted to and adsorbed onto the surface of an electrostatic latent image-bearing support by electrostatic attractive force.
• the image forming process making use of the electrostatic latent image should preferably be performed as quick as possible, and in this view, the heat roll fixing process, which has better heat efficiency and other advantages in comparison with other fixing processes of the art, has been widely applied in this field.
• the toner for the development is required to have a fixability at lower temperature, and for this purpose, the binder resin to be used should necessarily have a lower softening point.
• the softening point of the binder resin of a toner is lowered, a part of the toner image tends to be transferred to the surface of the heat roll and thus transferred toner is re-transferred to the surface of the subsequent transfer sheet, which is so-called an off-set phenomenon, to cause deterioration in the toner image.
• the heat roll fixing method there is a tendency that a transfer sheet easily winds round the surface of the heat roll, which is so-called a winding penomenon.
• toner should be fixable at lower temperature, having good off-set prevention and winding prevention properties.
• vinyl-type polymers have widely been used, and for the purpose of enhancing high off-set prevention property, it has been proposed to incorporate high molecular component into the binder resin.
• minimum fixing temperature the minimum temperature necessary to fix the toner
• the use of a polyester resin low molecular weight resin being readily obtainable, it is possible to obtain a toner having relatively low softening point.
• the toner using the polyester resin as a binder has, in comparison with the toner in which vinyl-type polymer is used, such an advantage that it has better wetting property against a transfer sheet such as paper and, therefore, fixing at lower temperature is possible comparing with the case where a vinyl-type polymer having approximately the same softening point.
• toner using a polyester resin as a binder generally has had such an disadvantage that the minimum temperature, at which off-set phenomenon takes place is low.
• it is effective to incorporate a high molecular weight component into the binder resin.
• the softening point of the binder resin as a whole is elevated, and, therefore the minimum fixing temperature rises and, again, the advantage of the heat roll fixing method comes to be lost.
• toner has a low minimum fixing temperature, and especially, in order to form a visual image on both sides of the parer it is almost essential that the toner for the development can be fixed at low temperature.
• a technique for lowering the minimum fixing temperature and for improving off-set and winding-up prevention properties of the toner was developed by incorporating a mold releasing agent selected from polyolefin waxes, such as polyethylene waxes or polypropylene waxes, into the toner particles.
• This technique is intended to confer a fixability at low temperature and mold releasing property on the toner itself, and is advantageous compared with such fixing ist, in which fixing is carried out while providing and coating a heat roller with a mold releasing oil such as silicone oil, in the view that there is no need for the fixing unit to be provided with a coating device of silicone oil and that the structure of the fixing unit may be made simpler.
• the prportion of such wax to be incorporated should often be considerably high and, as the result thereof, fluidity of the toner particles becomes lowered and the toner comes to bear a tendency to easily aggregate and to contaminate carrier particles, when used in a so-called two-component developer, sleeve in the developing unit and a support for the electrostatic latent image (photoreceptor) by forming a thin film of such wax component by adhesion, thus to jeopardise the function of these components in the electrophotograpgic copying machine.
• the present invention has been made under such circumstances and the object of the invention is to provide a toner for developing an electrostatic latent image which has a low minimum fixing temperature, sufficient off-set prevention property, good fluidity and durability, and which is capable of giving a number of visual images with high quality at high speed.
• the present invention specifically relates to toner for developing an electrostatic latent image which comprises (a) a binder resin consisting essentialy of a polyester containing not less than 5% by weight of chloroform-insoluble component and (b) at least one of a first mold releasing agent selected from compounds represented by the general formulae wherein R 1 and R 2 are independently selected from saturated or unsaturated aliphatic hydrocarbon groups having not less than 10 carbon atoms, R 3 and R 4 are independently selected from a hydrogen atom and a group represented by -oCR S wherein R 5 is a saturated or unsaturated hydrocarbon group and n is a positive integer, or (c) a combination of mold releasing agents selected from a secon mold releasing agent containing more than 20 % by weight of ester component, the needle penetration degree of said mold releasing agent being not more than 4, and a third mold releasing agent selected from polyolefin waxes and compounds of the general formula given above.
• a binder resin consisting essentialy of a polyester containing not
• the polyester resin used in the present invention can be obtained by condensation polymerization of a composition containing an alcohol monomer and a carboxylic acid monomer.
• diols including ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butane diol, neopentyl glycol, 1,4-butene diol; 1,4-bis(hydroxymethyl)cyclohexane: etherified bisphenols including bisphenol A, hydrogenated bisphenol A, a polyoxy-ethylenified bisphenol A, a polyoxypropionized bisphenol and other divalent alcoholic monomer may be mentioned.
• carboxylic acid monomers for example, maleic acid, fumaric acid, metaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, iso-phthalic acid, terephthalic acid, cyclohexane-di-carboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid and an anhydride thereof, a dimer of a lower alkylester and linole- nic acid and other dibasic organic acid may be mentioned.
• polyester resin used in the present invention in addition to those polymers obtained from above mentioned di-functional monomers, polymers containing a component derived from multi-functional monomers are also preferable.
• polyhydric alcohol monomers as for multi-functional monomers, for example, sorbitol, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tri-pentaerythritol, saccharose, 1,2,4-butanetiol, 1,2,5-pentanetiol, glycerol, 2-methylpropane-triol, 2-methyl-l,2,4-butanetriol, trimethylol ethane, trimethylol propane and 1,3,5-tri-hydroxymethyl benzene and the like can be mentioned.
• poly-basic acids for example, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzene tricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetri-carboxylic acid, 1,2,4-naphthalenetricaboxylic acid, 1,2,4-butanetricaboxylic acid, 1,2,4-haxanetricaboxylic acid, 1,3-dicarboxyl-z-methyl-2-methylenecarboxylic-propane, tetra(methylenecalboxylic)methane, 1,2,7,8-octane-tetracarboxylic acid, empol trimer acid, and acid anhydride of heretofore-mentioned organic acids can be mentioned.
• the component of multi-functional monomer of not less than tri- function is incorporated into the composition at a proportion of from 30 to 80 % by mole relative to the total of alcohol component and acid component respectively to be contained in the final polymer.
• the polyester resin used in the present invention contains a chloroform-insoluble component at a proportion of not less than 5% by weight.
• the chloroform-insoluble component in the present invention means a component which does not permeates through a filter paper when a sample is dissolved in chloroform and this is obtained by the following method.
• sample powder which has been prepared by finely pulverising a sampl resin and passed though a sieve of 40 meshes, together with 5.00g of Radiolite(#700) are put in a 150ml container and hereto 100g of chloroform is poured.
• the sample is thoroughly dissolven in chloroform by being rotated for more than 5 hours on the rotatable table.
• a filter paper(No.2) is placed in a pressure filter and thereon is coated uniformely 5.00g of Radiolite and after the filter paper is subjected to close contact with the pressure filter by the addition of small amount of chloroform, the solution in the container is pored into the pressure filter.
• the chloroform-insoluble component thus obtained is a high molecular weight polymer component or a cross-linked polymer component and the molecular weight thereof is assumed to be more than about 200,000.
• the chloroform-insoluble component of the present invention can be formed to in a controlled manner to a considerable extent by selecting the conditions for the polymerization of the hereinbefore mentioned alcohol and carboxylic acid, or by presenting an appropriate crosslinking agent in the reaction system.
• the chloroform-insoluble component is contained at a proportion not less than 5% by weight in the polyester resin.
• the minimum off-set occurring temperature will be insufficiently low.
• alkylenebisamide compounds available in the market the followings may be mentioned.
• BISAMIDE Nonto Chemical Ind., Co., Ltd.
• PLADFLOW Nitto Chemical Ind., Co., Ltd
• DIADD 200BIS Nippon Hygrogen Co., Ltd.
• LUBRON E Nippon Hydrogen Co., Ltd.
• AFLOW H50S Nippon Oil and Fats Co., Ltd.
• AFLOW V-60 Nippon Oil and Fats Co., Ltd.
• AMIDE 6-L Kawaken Fine Chemical Co.
• AMIDE 7-S Kawaken Fine Chemicak Co.
• ARMOWAX-EBS Lion-Armer Co.,)' "Hoechst Wax C” (Hoechst), “Nobuko Wax-22DS” (Nobuko Chemical Co.,), “Adva Wax-280” (Advance Co.,), “Kao Wax-EB”
• the mold releasing agent represented by the aforementioned formula generally has an increased softening point with the increase of the number of carbon atoms in the hydrocarbon group or of the length of the alkylene chain contained in the molecule.
• those having the softening point of 100 to 180°C, and more preferably, those having the softening temperature of 130 to 160°C are advantageously used in the present invention.
• n in the general formula be not more than 5.
• the preferable proportion of the amount of the mold releasing agent of this type to be contained in the toner conposition is within the range of 1 to 20% by weight relative to the binder resin and, more preferably, within the range of 1 to 10% by weight.
• the proportion to be contained is less than 1%, the effect as the mold releasing agent is hardly exerted and, accordingly, off-set prevention effect as well as winding prevention effect will be weakened. And good fixability of the toner at low temperature may not be obtained.
• the proportion exceeds 20% by weight the fluidity of the toner is likely to degrade, causing degrading of goog developability and transferability of the toner, thus to make the good image formation difficult.
• the mold releasing agent which is also used in the present invention is a combination of two kinds of releasing agents selected from a second mold releasing agent which is a wax containing therein as a component thereof an ester at a proportion of more than 20% by weight, together with other component such as higher fatty acids, higher alcohols or hydrocarbons, which may optionally be contained therein, and the needle penetration degree of which is not more than 4, and a third mold releasing agent selected from polyolefin waxes and compounds represented by the general formula given hereinbefore.
• the first mold releasing agent is selected from a wax having a melting point of between 60 and 110°C.
• the needle penetration degree is a value obtained in accordance with the measuring method described in JIS K2235-1980. That is to say, a sample wax which is heated and melted is taken in a sample container and, after the sample is left and cooled down, the sample is kept constant in its temperature at 25°C in a water bath. A needle the total mass of which is fixed to be 100g is then penetrated vertically into the sample wax for 5 minutes, and the depth of the needle thus penetrated is measured to the precision of O.lmm.
• the value of the needle penetration degree of the invention is defined as the value obtained by multiplying the depth by 10.
• the melting point of the wax can be obtained by Differential Scanning Calorimetory(DSC), i.e., the peak fusion value of the sample, when a few mg of sample was heated at a constant temperature rising rate of 10°C/min, is taken as the melting point.
• DSC Differential Scanning Calorimetory
• One of the third mold releasing agent used in the present invention is a polyolefin wax.
• polyolefin wax preferably used in the present invention, either unmodified polyolefins or modified polyolefins,
• the olkefin wax of the invention includes homopolymers or copolymers of the olefin which connsists of at least two olefin monomer components, copoymers containing as its monomer component an olefin monomer and another monomer other than olefin.
• any kinds of olefin may be used, for example, ethylene, propylene, butene-1, pentene-1, 3-methyl-l-butene, 3-methyl-2-pentene, etc.
• nonomer components other than olefins, which form copolymers together with olefins for example, vinyl-ethers such as vinyl methyether; vinyl esters such as vinyl acetate; halo- olefins such as vinyl fluoride; acrylic acid esters or methacrilic acid esters such as methyl acrylate or methyl methacrylate; acrylic acid derivatives such as acrylonitrile; organic acids such as acrylic acid and any othe monomer components which are coplymeriable with the olefin monomer.
• olefin copolymers such as ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copoly-mer, ethylene-vinyl methylether copolymer, ethylene-propylene-vinyl actate copolymer, etc. may be mentioned.
• a monomer component other than olefin mononer is used to form an olefin copolymer
• the proportion of the olefin part made of olefin monomer component in terms of molar % is preferably more than 50 % .
• Modifier component to form a modified polyolefin wax includes, for example, aromatic vinyl monomers such as 1-phenylpropene, styrene, methylstyrene, p-ethylstyrene, p-n-butylstyrene, etc., alpha-methylene aliphatic monocarbxylic acid esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, etc.
• aromatic vinyl monomers such as 1-phenylpropene, styrene, methylstyrene, p-ethylstyrene, p-n-butylstyrene, etc.
• alpha-methylene aliphatic monocarbxylic acid esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, etc.
• the proportion of the aromatic vinyl monomer component to be contained as a modifier component in the modified olefin coplymer is preferably within the range of from 0.1 to 15% by weight relative to the total modified polyolefin, and more preferably within the range of from 1 to 10% by weight.
• the proportion of the alpha-methylene aliphatic monocarboxylic acid ester monomer component to be contained as a modifier component will be within the range of from 0.1 to 50% by weight, and more preferably 1 to 40% by weight relative to the total modified polyolefin.
• the unmodified polyolefin or modified polymer thereof preferably used in the present invention advantageously has a low softening point of from 80 to 180°C, and more preferably 90 to 160°C, measured by the Ring and Ball method as defined in JIS K2531-1960.
• the preferable proportion of the total amount of mold releasing agents to be contained in the toner conposition in this case is within the range of 1 to 20% by weight relative to the binder resin and, more preferably, within the range of 1 to 10% by weight. Further the ratio of the first mold releasing agent against the second mold releasing agents is preferably within the range from 0.5 : 1 to 10 : 1, and more preferably, from 0.5 : 1 to 5 : 1. When the proportion of the second mold releasing agent is too small, there is observed a tendency that the off-set prevention effect is weakened, and when the proportion of the first mold releasing agent is too small, the minimum fixing temperature of the toner increases and insufficient fixing is likely to occur.
• the third mold releasing agents the polyolefin compound and the alkylene-bis-aliphatic acid amid compound may be incorporated into the toner composition altogether.
• Mixing ratio of the mold releasing agents in this case is optional provided that total proportion against the first mold releasing agent should preferably be within the range given hereinbefore with respect to the second or the third mold releasing agent.
• the toner of the present invention is in a fine powder form prepared by incorporating into and dispersing in the above-mentioned binder resin the mold releasing agent and, if necessary, other additives for the improvment of the properties of the toner, such as, colorant, magnetic material and the like.
• the average particle size of the toner is generally 5 to 30 microns.
• any conventionally known colorants and such colorant includes carbon black, Nigrosine(C.I. No. 504158), Aniline Blue( C.I. No. 50405), Ultranarine Blue(C.I. No. 77103), Chrome Yellow(C.I. No. 14090), Ouiniline Yellow(C.I. No. 47005), Rose Bengal(C.I. No. 45435), Du Pont Oil Red(C.I. No. 26105), Phthalocyanine Blue(C.I. No. 74160), Lamp Black(C.I. No. 77266), etc. and a mixture thereof may be used.
• the amount of the colorant to be incorporated into the toner of the present invention may not be limited but, in general, 1 to 20 parts by weight relative to 100 parts of the binder resin may be preferable.
• a magnetic material may be incorporated into the toner composition instead of, or together with the colorants.
• the magnetic material that may be used includes a compound or an alloy containing therein a ferromagnetic element such as iron, cobalt and nickel; ferrite, magnetite such an alloy as so-called Heusler's alloy which contains manganese and copper in the alloy, like Mn-Co-Al or Mn-Co-Sn, and whhich does not contain magnetic element but turns to show a ferromagnetic nature under suitable treatment by heat; or cromium dioxide, etc. may be mentioned.
• These magnetic materials are usually incorporated into and uniformely dispersed in the the toner composition in the form of a fine powder of the avarage particle size of 0.1 to 1 micron.
• the amount of the magnetic material to be incorporated is generally 20 to 70 parts by weight relative to 100 parts by weight of toner and, preferably, at a proportion of 40 to 70 parts by weight relative to the same.
• charge controlling agent for improving other properties of the toner
• fluidity improving lubricants such as fine powdery silica and the like may be mentioned.
• the toner of the present invention may be made as so-called two component developer, being mixed with carrier particles made of, for example, iron powder, glass beads, or so-called one component developer when the toner contains a magnetic material, both of which can be provided for the development of an electrostatic latent image.
• toner images with sufficient high density will be obtainable at relatively low temperature, without causing off-set phenomenon, at high speed and stably when the copying is repeated for a long time.
• binder resins and the mold releasing agents used are as follows:
• Binder Resin A (Accordfng to the present invention)
• a round bottomed flask equipped with a thermometer, a stainless steel stirrer, a glass tube through which to introduce nitrogen and a condenser was charged with 299g of telephthalic acid, 211g of polyoxypropylene(2,2)-2,2-bis( 4-hydroxy phenyl)propane and 82g of pentaerythritol.
• the flask was set in a mantle heater and heated while nitrogen gas was introduced into the flask to keek its interior under an inert atomosphere.
• 0.05g of dibutyl tin oxide was added, and reduction was carried out at 200°C while the softening point was used as a parameter to monitor the progress of the reaction.
• a polyester resin A having a softening point of 131°C and containing 17 % by weight of chloroform-insoluble component was obtained. 4
• Mold Releasing Agent a2 (The First or the Third Wax) "BISAMIDE” (Nitto Chemical Ind., Co., Ltd.) Mold Releasing Agent a3 (The First or the Third Wax) "ARMOWAX - EBS” (Lion-Armer Co.,)” Mold Releasing Agent bl (The Second Wax) "Carnauba Wax No.
• the toner components shown in TABLE 1 were mixed and neaded in a extruder, the temperature of the inside thereof having been fixed to the one which is below the softening point of the resin used by 10°C. Then the mixture was cooled down by water, pulverized and classified to obtain a toner having the average particle size of 11 microns. Finally 0.8% by weight of hydrophobic silica was added to the thus prepared tone, to prepare the toner of the Examples.
• the numerals in the brackets are given in terms of parts by weight.
• Toners 1 to 9 and the toners for comparison (Comparative Toners 1 to 6) were subjected to various tests evplained below.
• the bulk density of the respective toners were measured in order to determine the fluidity of the toners.
• the respective toners were poured down into a container having a diameter of 28mm and the total volume of 100ml to its full through a sieve of 100 mesh and the weight was measured.
• the respective toners were mixed with a resin coated carrier to prepare as many developers, of which toner content was 2% by weight respectively.
• a heat roll fixing unit consisting of a heat roll, the surface of which is formed of TEFLON ( polytetrafluoroethylene produced by du Pont), and a pressure roll, the surface of which is formed of a silicone rubber "KE-1300 RTV" (product of Shinetsu Chemical Industry Co., Ltd.), was carried out by passing through the fixing unit a sample transfer sheet, onto which 64 g/m 2 of toner has been adhered, at a line feeding speed of 200mm/sec, and this procedure was repeated while increasing stepwise the temperature of the heat roll by 5°C from 100°C.
• the fixed toner image thus obtained was subjected to rubbing test with KIM wiper and the minimum fixing temperature was determined as the lowest temperature at which the fixed toner image has a sufficient durability against rubbing.
• the fixing unit used does not have a silicone oil providing device.
• the the lowest temperature at which off-set phenomenon is first observed was determined in the similar manner as in the determination of the minimum fixing temperature, that is, the temperature at which the off-set phenomenon is first observed was measured by, first, developing an electrostatic image formed in an ordinary electrophotographic method with a developer and, transferring the toner image onto a plain paper sheet and fixing the transferred image in the above-mentioned fixing unit, and, thereafter, by passing a white paper through the fixing unit under the same conditions, to observe if any contamination is seen on the surface of the white paper due to the toner attached to the roll in the fixing unit.
• the temperature, at which off-set phenomenon is first seen was obtained.
• winding occurrence temperature was measured by the use of a uniformly black original, whereby toner was made attached to the whole surface of the transfer sheet by development and transfer processes, and by carrying out fixing test while lowering stepwise the temperature of the heat roll of the fixing unit.
• the toner of the present invention has higher off-set anf winding prevention ability, fixability at reduced temperature, excellent developability with sufficient density and excellent stability in image formation aafter long time repetition of copying in comparison with the toner of the prior art. Further no serious contamination in the sleeve of the developing unit or in the surface of the photoreceptor was observed even after 60000 times of copying.
• the comparative toner shows lower off-set coccurring temperature, inferior image quality and inferior stability in the image formation.

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• Chemical Kinetics & Catalysis (AREA)
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• 1985
  • 1985-05-29 EP EP85303774A patent/EP0163528A3/de not_active Withdrawn

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