CA1115582A - Toner powder containing an epoxy resin with epoxy groups modified by reaction with a monofunctional carboxylic acid and/or a monofunctional phenol - Google Patents
Toner powder containing an epoxy resin with epoxy groups modified by reaction with a monofunctional carboxylic acid and/or a monofunctional phenolInfo
- Publication number
- CA1115582A CA1115582A CA277,802A CA277802A CA1115582A CA 1115582 A CA1115582 A CA 1115582A CA 277802 A CA277802 A CA 277802A CA 1115582 A CA1115582 A CA 1115582A
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- Prior art keywords
- epoxy
- toner powder
- resin
- monofunctional
- phenol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/14—Polycondensates modified by chemical after-treatment
- C08G59/1433—Polycondensates modified by chemical after-treatment with organic low-molecular-weight compounds
- C08G59/1438—Polycondensates modified by chemical after-treatment with organic low-molecular-weight compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/14—Polycondensates modified by chemical after-treatment
- C08G59/1433—Polycondensates modified by chemical after-treatment with organic low-molecular-weight compounds
- C08G59/1438—Polycondensates modified by chemical after-treatment with organic low-molecular-weight compounds containing oxygen
- C08G59/1455—Monocarboxylic acids, anhydrides, halides, or low-molecular-weight esters thereof
-
- 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
- G03G9/08753—Epoxyresins
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Polymers & Plastics (AREA)
- Medicinal Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Emergency Medicine (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Developing Agents For Electrophotography (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Positively chargeable toner powder comprising finely divided, coloured toner particles containing an insulating thermoplastic resin, colouring materials and a polarity control agent, the thermoplastic resin including at least 50% by weight of an epoxy resin having an epoxy molar mass of at least 10,000, said epoxy molar mass being achieved by modification of at least 5% of its epoxy groups with a monofunctional carboxylic acid and/or a monofunctional phenol which carry, except for the carboxyl or hydroxyl group respectively, no substituents which are reactive towards the epoxy groups of the epoxy resin, under the conditions of preparing the toner powder, and by modification of no more than 95%
by intermolecular reaction or by cross-linking with the aid of a poly-functional epoxy hardener. The toner powder gives improved uniform chargeability, charge stability and permanence, reproducibility of the fusing properties, thermal stability and sensitivity to moisture.
Positively chargeable toner powder comprising finely divided, coloured toner particles containing an insulating thermoplastic resin, colouring materials and a polarity control agent, the thermoplastic resin including at least 50% by weight of an epoxy resin having an epoxy molar mass of at least 10,000, said epoxy molar mass being achieved by modification of at least 5% of its epoxy groups with a monofunctional carboxylic acid and/or a monofunctional phenol which carry, except for the carboxyl or hydroxyl group respectively, no substituents which are reactive towards the epoxy groups of the epoxy resin, under the conditions of preparing the toner powder, and by modification of no more than 95%
by intermolecular reaction or by cross-linking with the aid of a poly-functional epoxy hardener. The toner powder gives improved uniform chargeability, charge stability and permanence, reproducibility of the fusing properties, thermal stability and sensitivity to moisture.
Description
5~
The present invention relates to toner powder for the development of latent electrostatic images. The invention relates in particular to a toner powder which can be charged positively and substantially consists of finely divided, coloured toner particles containing an insulating thermoplas-tic resin, colouring materials and a polarity control agent. The present invention also relates to a process for preparing such a toner powder and to a two-component developer containing such a toner powder.
In electrophotography, latent electrostatic images are formed on a suitable surface. To make these images visible, powder developers of the so called two-component type are widely used. These are developers containing fine, black or otherwise coloured toner particles and comparatively big carrier particles. Upon contact with or friction against the carrier particles the toner particles have an electrostatic charge, and as a result they adhere to the carrier particles. In general, the composition of toner and carrier particles is chosen such that the toner particles accept a charge of a polar-ity opposite to that of the latent electrostatic image to be developed. When the toner powder is brought into contact with this image, the toner particles are released from the carrier particles by the electrostatic charge of the image, and`are deposited on the latent image, as a result of which this be-comes visible. In direct electrophotography the powder image is generally fixed by heat onto the surface on which it has been deposited. In indirect electrophotography the powder image is transferred to a receiving surface and fixed thereon. Heating mostly occurs by radiant heat, in a so-called radia-tion fusing device, or by bringing the powder image in a so-called contact-fusing device into contact with a heated surface, such as a roller and/or a belt, a combination of heat and pressure fixing thus being effected The two-component powder developers may contain, as carrier particles, powdered mat-erials of widely varying composition, They may consist, for example, of metal, e.g. iron or nickel, metallic oxide, e,g. chromium oxide or alwninium oxide, glass, sand or quart7. Metal carrier particles, especially iron particles, - 1 - ~, , ~ , '_f are frequently used in practice. ~n particular iron particles are frequently used in powder developers for use in the so-called magnetic brush development, in which technique the developer is carried by magnetic transport means to the electrostatic image to be developed.
The toner particles in the two~component powder developers sub-stantially consist of an insulating, thermoplastic resin, or a mixture of such resins, and one or ~ore colouring materials. The conventional natural and synthetic polymers are used as thermoplastic resins. Examples of thermoplastic resins, which are extensively used, are poiystyrene, copolymers of styrene with an acrylate and/or, methacrylate, polyamides, modified phenolformaldehyde resins~ polyester resins and epoxy resins. Carbon black is generally added as colouring material in black toner powders, and in coloured toner powders employed, for example, in electrophotographic multi-colour reproduction pro-cesses, organic dyes are added to the thermoplastic resin.
Generally, the above-mentioned resins themselves cannot be charged positively to a sufficient extent. Most of them are charged negatively upon contact with iron particles. Thus, the addition of a polarity control agent, i.e. an agent making the triboelectric charge sufficiently positive, is re- ;
quired if a positively chargeable two-component powder developer suitable for ZO magnetic brush development is desired. Polarity control agents that have proved effective include amino compounds, quaternary ammonium compounds and organic dyes, in particular basic dyes and their salts, such as the hydro-chlorides. Examples of conventional polarity control agents are benzyl, dimethyl-hexadecyl ammonium chloride and decyl-trimethyl ammonium chloride, nigrosine base, nigrosine hydrochloride, Safranine T and Crystal Violet.
Especially nigrosine base and nigrosine hydrochloride are often used as polar-ity control agent. ~ ;
The basic requirements which a toner powder in general, and a posi-tively chargeable toner powder in particular must meet, are pronounced polar-ity, good charging characteristics such as sufficient chargeability, uniform i charge distribution, charge stability and low sensitivity to moisture andtemperature, good fusing properties that are also properly reproducible, thermal stability and a good permanence during prolonged use. ~loreover, for a toner powder to be used in an electrocopier with a contact-fusing device the fusing range should desirably be as broad as possible. Por use in a copying apparatus with a radiation fusing device the fusing range should pre-ferably be as small as possible.
Though a number of the negatively chargeabl~ toner powders proposed hitherto satisfy the above-mentioned properties to a fair degree, with the positively chargeable toner powders this is the case to a far lesser degree.
This can be said in particular of their charge stability, reproducibility of the fusing properties, thermal stability and, especially, of their uniform chargeability and permanence. To obtain uniform chargeability with a good permanence of the toner particles, the polarity control agent must be distri-buted fully homogeneously throughout the resin. As is well known, toner pow-ders are generally prepared by means of the so-called kneading method, the extrusion method or the hot melt method. In these processes, the resin is homogeneously mixed in a molten state with the colouring materials, the polar-ity control agent and, if desired, other ingredients. After cooling down the
The present invention relates to toner powder for the development of latent electrostatic images. The invention relates in particular to a toner powder which can be charged positively and substantially consists of finely divided, coloured toner particles containing an insulating thermoplas-tic resin, colouring materials and a polarity control agent. The present invention also relates to a process for preparing such a toner powder and to a two-component developer containing such a toner powder.
In electrophotography, latent electrostatic images are formed on a suitable surface. To make these images visible, powder developers of the so called two-component type are widely used. These are developers containing fine, black or otherwise coloured toner particles and comparatively big carrier particles. Upon contact with or friction against the carrier particles the toner particles have an electrostatic charge, and as a result they adhere to the carrier particles. In general, the composition of toner and carrier particles is chosen such that the toner particles accept a charge of a polar-ity opposite to that of the latent electrostatic image to be developed. When the toner powder is brought into contact with this image, the toner particles are released from the carrier particles by the electrostatic charge of the image, and`are deposited on the latent image, as a result of which this be-comes visible. In direct electrophotography the powder image is generally fixed by heat onto the surface on which it has been deposited. In indirect electrophotography the powder image is transferred to a receiving surface and fixed thereon. Heating mostly occurs by radiant heat, in a so-called radia-tion fusing device, or by bringing the powder image in a so-called contact-fusing device into contact with a heated surface, such as a roller and/or a belt, a combination of heat and pressure fixing thus being effected The two-component powder developers may contain, as carrier particles, powdered mat-erials of widely varying composition, They may consist, for example, of metal, e.g. iron or nickel, metallic oxide, e,g. chromium oxide or alwninium oxide, glass, sand or quart7. Metal carrier particles, especially iron particles, - 1 - ~, , ~ , '_f are frequently used in practice. ~n particular iron particles are frequently used in powder developers for use in the so-called magnetic brush development, in which technique the developer is carried by magnetic transport means to the electrostatic image to be developed.
The toner particles in the two~component powder developers sub-stantially consist of an insulating, thermoplastic resin, or a mixture of such resins, and one or ~ore colouring materials. The conventional natural and synthetic polymers are used as thermoplastic resins. Examples of thermoplastic resins, which are extensively used, are poiystyrene, copolymers of styrene with an acrylate and/or, methacrylate, polyamides, modified phenolformaldehyde resins~ polyester resins and epoxy resins. Carbon black is generally added as colouring material in black toner powders, and in coloured toner powders employed, for example, in electrophotographic multi-colour reproduction pro-cesses, organic dyes are added to the thermoplastic resin.
Generally, the above-mentioned resins themselves cannot be charged positively to a sufficient extent. Most of them are charged negatively upon contact with iron particles. Thus, the addition of a polarity control agent, i.e. an agent making the triboelectric charge sufficiently positive, is re- ;
quired if a positively chargeable two-component powder developer suitable for ZO magnetic brush development is desired. Polarity control agents that have proved effective include amino compounds, quaternary ammonium compounds and organic dyes, in particular basic dyes and their salts, such as the hydro-chlorides. Examples of conventional polarity control agents are benzyl, dimethyl-hexadecyl ammonium chloride and decyl-trimethyl ammonium chloride, nigrosine base, nigrosine hydrochloride, Safranine T and Crystal Violet.
Especially nigrosine base and nigrosine hydrochloride are often used as polar-ity control agent. ~ ;
The basic requirements which a toner powder in general, and a posi-tively chargeable toner powder in particular must meet, are pronounced polar-ity, good charging characteristics such as sufficient chargeability, uniform i charge distribution, charge stability and low sensitivity to moisture andtemperature, good fusing properties that are also properly reproducible, thermal stability and a good permanence during prolonged use. ~loreover, for a toner powder to be used in an electrocopier with a contact-fusing device the fusing range should desirably be as broad as possible. Por use in a copying apparatus with a radiation fusing device the fusing range should pre-ferably be as small as possible.
Though a number of the negatively chargeabl~ toner powders proposed hitherto satisfy the above-mentioned properties to a fair degree, with the positively chargeable toner powders this is the case to a far lesser degree.
This can be said in particular of their charge stability, reproducibility of the fusing properties, thermal stability and, especially, of their uniform chargeability and permanence. To obtain uniform chargeability with a good permanence of the toner particles, the polarity control agent must be distri-buted fully homogeneously throughout the resin. As is well known, toner pow-ders are generally prepared by means of the so-called kneading method, the extrusion method or the hot melt method. In these processes, the resin is homogeneously mixed in a molten state with the colouring materials, the polar-ity control agent and, if desired, other ingredients. After cooling down the
2~ solid mass so obtained is ground to particles of the desired degree of fine-ness, and all these particles must have exactly the same composition, in order to get a toner powder by which a good image quality can be obtained. However, the positive acting polarity control agents whlch are preferably used often do not or only sparingly dissolve in the the~moplastic resins or mixtures of resins to be used for the toner powders, as a result of which the desired homogeneity cannot be obtained. This can be said in particular of the highly preferred nigrosine base and nigrosine hydrochloride.
In the ~ew cases where there are positive acting polarity control agents that, for the purpose intended, do dissolve sufficiently in the thermo-
In the ~ew cases where there are positive acting polarity control agents that, for the purpose intended, do dissolve sufficiently in the thermo-
3~ plastic resin, as is the case with polyamides, e.g , the resin itself has several not quite favourable yroperties, as a result of which toner yowdersprepared on that basis do not fulfill very well the aforementioned basic pro-perties such as, for examyle, the sensitivity of the charye to moisture and temperature.
I'he object of the present invention is to provide a positively chargeable toner powder which in general meets the afore-mentioned ~asic requirements and, in particular, largely meets the requirements that proved hard to be realized, especially for positively chargeable toner powders, in respect of uniform chargeability, charge stability and permanence, reproduci-bllity of the fusing properties, thermal stability c~nd sensitivity to mois-ture. A further object is -to provide a method by which the toner powder according to the invention can be manufactured tailor-made in a simple and economic way.
The present invention provides a positively chargeable toner powder characterized by stability at temperatures up to 50C and a melting point of about 65 to 150C, which comprises finely divided toner particles containing an insulating thermoplastic resin, colouring materials, and a polarity control agent, the thermoplastic resin including at least 50% by weight of a modified epoxy resin having an epoxy molar mass ~grams resin/
grams equivalent of epoxy) of at least 10,000, at least 5% of epoxy gr~ups of the mcdified epoxy resin modified with a monofunctional carboxylic acid and/or a monofunctional phenol by reaction with the respective carboxyl or hydroxyl groups thereof, and, optionally, no m~re than 95% of epoxy groups of the modified epoxy resin modified by intermolecular reaction and/or by cross-linking with a ~olyfunctional epoxy hardener.
In another aspect, the present invention comprises a process of preparing the above defined toner powder, the process comprising the steps of homogeneously mLxing the thermoplastic resin in a molten s-tate with the polarity control agent and colouring materials ~ ' .
:
` ~ ` o:
cooling the mass ~lus obtained, 3nd grinding said cooled n~ss to the desired degree of finen-ss, wherein epoxy groups of an epoxy resin oE lc~er epoxy molar mass chosen as starting ma-terial are n~dified with the monofunctional carboxylic acid and/or phenol durlng said mixing of the ingredients, and optionally wherein modification during said mixing of the ingredients is also achieved by inter-molec~ular reaction and/or cross-linking with the poly-functional hardener.
sy epoxy resins are meant in the context of this invention conden-sation products of a polyphenol, in particular a bisphenol, with a halohydrin in particular epichlorohydrin.
The modiEied epoxy resin to be used in the toner pc~er a~cording to the invention can be obtained, for example, by modifying in the way indi-cated above one of the commercially available epoxy resins, or a mixture of such resins, which, as .t is well knc~n, have an epoxy mol~r mass (herein-after referred to as E.M.M.) being considerably below the minimum of 10,000 required in the present case. By epoxy n~lar mass is meant the mass of resin in grams which contains one gram equivalent of epoxy :(see pages 4 14 Of "Hanc~ook of Epoxy Resins" by Lee and Neville, McGraw Hill sook Company, - 1967). Epoxy molar mass was for~erly referred to in the art as epoxy eqlivalent mass. The choice of the resin or resins to be used as starting product for this purpose is mainly determined by the requirement that the toner powder must be stable at temperatures up to 50C, and that it must have a melting poin-t between 55 and 150C. m e first requirement is connected with the aspect that, till the fusing step, temperatures up to 50C may occur in every stage, such as storing, staying and processing, in the copying apparatus. me second requirement is especially connected with the maximumallc~able temperature of the copying paper cluring fusing, because utherwise discolouration or even burning may occur. In copying apparatus in which a less inflammable substratum than paper, for exar~le, glass or metal is employed, resins having a higher mel-ting point can, of coarse, also be used for the toner powder.
EYamples of epoxy resins that are quite useful as starting product for the preparation of the modified epoxy resin to be applied in -the toner ~ ~ .
~ . . -powder according to the invention are Epikote 100~* ~melting point 90 - 100C, E.M.M. 850 - 940, both data according to supplier~s specifications), Epikote 1006* ~115 - 125C, E.M.M. 1~550 - 1,900), Epikote 1007* ~120 - 130C, E.M.M. 1,700 - 2,050), and Epikote 100~* ~1~0 - 155C, E.M.M. 2,300 - 3,~00).
Howe~er, as will be explained hereafter in the specification, under certain circumstances it is also possible to use epoxy resins having lower or higher melting points than those mentioned above as starting product.
The toner powder according to the invention may contain epoxy resin of which between 5 and 100% of the epoxy groups are modified with a monofunctional carboxylic acid andjor phenol. The required E.M.M. of 10,000 or higher can be obtained by modifying approximately 80 to 100% of the epoxy groups of the epoxy resin chosen as starting product with a monofunctional carboxylic acid and/or phenol. However, it can also be achieved by modifying at least approximately 80% of the epoxy groups of the epoxy resin partly with a monofunctional carboxylic acid and/or phenol, and partly by inter-molecular reaction. Of course, it must then be ensured during the modifica-tion process that the conditions required for performing both kinds of modifications are available. In general, these are satisfied if the tempera-ture and duration of the modification process are properly selected. The intermolecular reaction between the epoxy groups of the epoxy resin generally proceeds satisfactorily at temperatures of between 150 and 250C and resi-dence time of 120 secs. to 5 minutes. At the said tempe~atures modification by means of the monofunctional carboxylic acid and/or phenol proceed considera-bly faster than the intermolecular reaction.
The desired minimum E.M.M. can be obtained as well by combining the modification by means of a monofunctional carboxylic acid and/or phenol with a modification performed by cross-linking, using one of the polyfunctional epoxy hardeners known per se. Examples of hardeners suitable for the purpose *Trade Marks ~ -6-''~3 ~, are succinic anhydride, maleic anhydride, succinic acid and bisphenol A. As such cross-linking reactions generally proceed very quickly at 110 to 150C~
said combination leads to the desired result, already within several minutes, when the modification takes place at temperatures between round 100 and 150Co In all cases, however, at least 5% of the epoxy groups of the epoxy resin chosen as starting product for the preparation of the toner pow-der according to the invention must be modified with a monofunctional car-boxylic acid and/or phenol, because otherwise the toner powder does not meet the requirements made hereinbefore in respect of melting point and repro-ducibility of the fusing behaviour.
Which percentage of the epoxy groups is modified with a mono-functional carboxylic acid and/or phenol, and which by intermolecular reaction and epoxy hardening, respectively, depends on the purpose the toner powder according to the invention has to serve.
If the toner powder is intended for the preparation of a developer for use in apparatus equipped with a radiation fusing device, it is advisable to modify a percentage as high as possible but, in general, at least 50%, and preferably at least 75% of the epoxy groups of the resin chosen as start-ing product, with a carboxylic acid and/or phenol. The fact is that for use in a radiation fusing device the toner powder should have a fusing range as small as possible with an initial melting point as low as possible. By modifying as high as possible a percentage of the epoxy groups with a mono-functional carboxylic acid and/or phenol, and a percentage as low as possible by intermolecular reaction or by epoxy hardening, the fusing range, mostly being rather small itself, and the initial melting point of the epoxy resin chosen as starting product for performing the modification, are only changed *o a practically negligible extentO
An additional advantage of a modification almost exclusively with a monofunctional carboxylic acid and/or phenol is that ~he modification can be performed very quickly and at relatively low temperatures in a highly reproducible way.
If the toner powder is intended $or the preparation of a developer to be used in contact-fusing devices, which are preferred to radiation fusing devices especially in copying apparatus which are to attain high printing speeds, the best results will be obtained according to whether the modification of the epoxy groups of the resin, chosen as starting product, with a monofunctional carboxylic acid and/or phenol is closer in the neigh-bourhood of the required minimum rate of 5%~ whereas the remaining modifica-tion percentage, required for attaining the minimum epoxy molar mass of ~-10,000, is obtained by intermolecular reaction between the epoxy groups of the epoxy resin or by epoxy hardening. The resin so obtained and, thus, the toner powder prepared therefrom has a large fusing range, which is a de-sired property for toner powders for developers intended for use in apparatus equipped with a contact-fusing device. In general, the fusing range of the modified epoxy resin increases as the percentage of modification with a mono-functional carboxylic acid and/or phenol is nearer to the minimum rate of 5%.
However, the melting point of the modified resin then shifts to a higher level, so that it may be desired, in certain cases, to modify more than 5% of the epoxy groups with a monofunctional carboxylic acid and/or phenol, because otherwise the melting point of the resin obtained will be too high for proper and economical fusing. However, within certain limits this drawback may be met by starting from an epoxy resin having a relatively low melting point, such as Epikote* 10049 1002 or 1001.
But for the carboxyl and hydroxyl group, respectively) the mono-functional carboxylic acids and/or phenols to be used for the modification of the epoxy resin chosen as starting product may not contain any further sub-stituent that might react with the epoxy groups of the epoxy resin under the ` conditions prevailing during the modification process.
Particularly suitable are aliphatic and aromatic carboxylic acids and phenols, as well as those which are substituted by one or more alkyl, *Trade Mark - ~ f~ ~
aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy or aryloxy groups, and which are not volatile, or substantially not, under the conditions prevailing during the modification process.
Examples of such carboxylic acids are benzoic acid, 2, 4-dimethyl-benzoic acid, 4-~a,a-dimethylbenzyl)-benzoic acid, 4-phenylbenzoic acid and
I'he object of the present invention is to provide a positively chargeable toner powder which in general meets the afore-mentioned ~asic requirements and, in particular, largely meets the requirements that proved hard to be realized, especially for positively chargeable toner powders, in respect of uniform chargeability, charge stability and permanence, reproduci-bllity of the fusing properties, thermal stability c~nd sensitivity to mois-ture. A further object is -to provide a method by which the toner powder according to the invention can be manufactured tailor-made in a simple and economic way.
The present invention provides a positively chargeable toner powder characterized by stability at temperatures up to 50C and a melting point of about 65 to 150C, which comprises finely divided toner particles containing an insulating thermoplastic resin, colouring materials, and a polarity control agent, the thermoplastic resin including at least 50% by weight of a modified epoxy resin having an epoxy molar mass ~grams resin/
grams equivalent of epoxy) of at least 10,000, at least 5% of epoxy gr~ups of the mcdified epoxy resin modified with a monofunctional carboxylic acid and/or a monofunctional phenol by reaction with the respective carboxyl or hydroxyl groups thereof, and, optionally, no m~re than 95% of epoxy groups of the modified epoxy resin modified by intermolecular reaction and/or by cross-linking with a ~olyfunctional epoxy hardener.
In another aspect, the present invention comprises a process of preparing the above defined toner powder, the process comprising the steps of homogeneously mLxing the thermoplastic resin in a molten s-tate with the polarity control agent and colouring materials ~ ' .
:
` ~ ` o:
cooling the mass ~lus obtained, 3nd grinding said cooled n~ss to the desired degree of finen-ss, wherein epoxy groups of an epoxy resin oE lc~er epoxy molar mass chosen as starting ma-terial are n~dified with the monofunctional carboxylic acid and/or phenol durlng said mixing of the ingredients, and optionally wherein modification during said mixing of the ingredients is also achieved by inter-molec~ular reaction and/or cross-linking with the poly-functional hardener.
sy epoxy resins are meant in the context of this invention conden-sation products of a polyphenol, in particular a bisphenol, with a halohydrin in particular epichlorohydrin.
The modiEied epoxy resin to be used in the toner pc~er a~cording to the invention can be obtained, for example, by modifying in the way indi-cated above one of the commercially available epoxy resins, or a mixture of such resins, which, as .t is well knc~n, have an epoxy mol~r mass (herein-after referred to as E.M.M.) being considerably below the minimum of 10,000 required in the present case. By epoxy n~lar mass is meant the mass of resin in grams which contains one gram equivalent of epoxy :(see pages 4 14 Of "Hanc~ook of Epoxy Resins" by Lee and Neville, McGraw Hill sook Company, - 1967). Epoxy molar mass was for~erly referred to in the art as epoxy eqlivalent mass. The choice of the resin or resins to be used as starting product for this purpose is mainly determined by the requirement that the toner powder must be stable at temperatures up to 50C, and that it must have a melting poin-t between 55 and 150C. m e first requirement is connected with the aspect that, till the fusing step, temperatures up to 50C may occur in every stage, such as storing, staying and processing, in the copying apparatus. me second requirement is especially connected with the maximumallc~able temperature of the copying paper cluring fusing, because utherwise discolouration or even burning may occur. In copying apparatus in which a less inflammable substratum than paper, for exar~le, glass or metal is employed, resins having a higher mel-ting point can, of coarse, also be used for the toner powder.
EYamples of epoxy resins that are quite useful as starting product for the preparation of the modified epoxy resin to be applied in -the toner ~ ~ .
~ . . -powder according to the invention are Epikote 100~* ~melting point 90 - 100C, E.M.M. 850 - 940, both data according to supplier~s specifications), Epikote 1006* ~115 - 125C, E.M.M. 1~550 - 1,900), Epikote 1007* ~120 - 130C, E.M.M. 1,700 - 2,050), and Epikote 100~* ~1~0 - 155C, E.M.M. 2,300 - 3,~00).
Howe~er, as will be explained hereafter in the specification, under certain circumstances it is also possible to use epoxy resins having lower or higher melting points than those mentioned above as starting product.
The toner powder according to the invention may contain epoxy resin of which between 5 and 100% of the epoxy groups are modified with a monofunctional carboxylic acid andjor phenol. The required E.M.M. of 10,000 or higher can be obtained by modifying approximately 80 to 100% of the epoxy groups of the epoxy resin chosen as starting product with a monofunctional carboxylic acid and/or phenol. However, it can also be achieved by modifying at least approximately 80% of the epoxy groups of the epoxy resin partly with a monofunctional carboxylic acid and/or phenol, and partly by inter-molecular reaction. Of course, it must then be ensured during the modifica-tion process that the conditions required for performing both kinds of modifications are available. In general, these are satisfied if the tempera-ture and duration of the modification process are properly selected. The intermolecular reaction between the epoxy groups of the epoxy resin generally proceeds satisfactorily at temperatures of between 150 and 250C and resi-dence time of 120 secs. to 5 minutes. At the said tempe~atures modification by means of the monofunctional carboxylic acid and/or phenol proceed considera-bly faster than the intermolecular reaction.
The desired minimum E.M.M. can be obtained as well by combining the modification by means of a monofunctional carboxylic acid and/or phenol with a modification performed by cross-linking, using one of the polyfunctional epoxy hardeners known per se. Examples of hardeners suitable for the purpose *Trade Marks ~ -6-''~3 ~, are succinic anhydride, maleic anhydride, succinic acid and bisphenol A. As such cross-linking reactions generally proceed very quickly at 110 to 150C~
said combination leads to the desired result, already within several minutes, when the modification takes place at temperatures between round 100 and 150Co In all cases, however, at least 5% of the epoxy groups of the epoxy resin chosen as starting product for the preparation of the toner pow-der according to the invention must be modified with a monofunctional car-boxylic acid and/or phenol, because otherwise the toner powder does not meet the requirements made hereinbefore in respect of melting point and repro-ducibility of the fusing behaviour.
Which percentage of the epoxy groups is modified with a mono-functional carboxylic acid and/or phenol, and which by intermolecular reaction and epoxy hardening, respectively, depends on the purpose the toner powder according to the invention has to serve.
If the toner powder is intended for the preparation of a developer for use in apparatus equipped with a radiation fusing device, it is advisable to modify a percentage as high as possible but, in general, at least 50%, and preferably at least 75% of the epoxy groups of the resin chosen as start-ing product, with a carboxylic acid and/or phenol. The fact is that for use in a radiation fusing device the toner powder should have a fusing range as small as possible with an initial melting point as low as possible. By modifying as high as possible a percentage of the epoxy groups with a mono-functional carboxylic acid and/or phenol, and a percentage as low as possible by intermolecular reaction or by epoxy hardening, the fusing range, mostly being rather small itself, and the initial melting point of the epoxy resin chosen as starting product for performing the modification, are only changed *o a practically negligible extentO
An additional advantage of a modification almost exclusively with a monofunctional carboxylic acid and/or phenol is that ~he modification can be performed very quickly and at relatively low temperatures in a highly reproducible way.
If the toner powder is intended $or the preparation of a developer to be used in contact-fusing devices, which are preferred to radiation fusing devices especially in copying apparatus which are to attain high printing speeds, the best results will be obtained according to whether the modification of the epoxy groups of the resin, chosen as starting product, with a monofunctional carboxylic acid and/or phenol is closer in the neigh-bourhood of the required minimum rate of 5%~ whereas the remaining modifica-tion percentage, required for attaining the minimum epoxy molar mass of ~-10,000, is obtained by intermolecular reaction between the epoxy groups of the epoxy resin or by epoxy hardening. The resin so obtained and, thus, the toner powder prepared therefrom has a large fusing range, which is a de-sired property for toner powders for developers intended for use in apparatus equipped with a contact-fusing device. In general, the fusing range of the modified epoxy resin increases as the percentage of modification with a mono-functional carboxylic acid and/or phenol is nearer to the minimum rate of 5%.
However, the melting point of the modified resin then shifts to a higher level, so that it may be desired, in certain cases, to modify more than 5% of the epoxy groups with a monofunctional carboxylic acid and/or phenol, because otherwise the melting point of the resin obtained will be too high for proper and economical fusing. However, within certain limits this drawback may be met by starting from an epoxy resin having a relatively low melting point, such as Epikote* 10049 1002 or 1001.
But for the carboxyl and hydroxyl group, respectively) the mono-functional carboxylic acids and/or phenols to be used for the modification of the epoxy resin chosen as starting product may not contain any further sub-stituent that might react with the epoxy groups of the epoxy resin under the ` conditions prevailing during the modification process.
Particularly suitable are aliphatic and aromatic carboxylic acids and phenols, as well as those which are substituted by one or more alkyl, *Trade Mark - ~ f~ ~
aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy or aryloxy groups, and which are not volatile, or substantially not, under the conditions prevailing during the modification process.
Examples of such carboxylic acids are benzoic acid, 2, 4-dimethyl-benzoic acid, 4-~a,a-dimethylbenzyl)-benzoic acid, 4-phenylbenzoic acid and
4-ethoxybenzoic acid. Further, the satured aliphatic carboxylic acids;
heptanoic acid, nonanoic acid, dodecanoic and isododecanoic acid, hexadecanoic acid and octadecanoic acid.
Examples of the above phenolic compounds are 4-n-butyl phenol, 4-n-pentyl phenol, 2, 3, 4, 6-tetramethyl phenol, 2, 3, 5, 6-tetramethyl phenol, 4-~a,a-dimethyl) benzyl phenol, 4-cyclohexyl phenol, 3-methoxy phenol, 4-methoxy phenol and 4~ethoxy phenol.
Of the compounds mentioned above octadecanoic acid, subs~ituted or non-substituted benzoic acid and 4-~a,a-dimethyl) benzyl phenol are most preferably used.
The modification of the epoxy resin chosen as starting product to ~;
become the modified epoxy resin for use in the toner powder according to the invention preferably occurs during preparation of the toner powder itself.
Surprisingly it has appeared that in this way the modification process can be performed well and be controlled satisfactorily, so that in thls way a tailor-made toner powder of excellent quality can be obtained. Moreover, in that case no special catalyst or other additive is required for performing the modification with the monofunctional carboxylic acid and/or phenol satisfactorily, which is an additional advantage.
Admittedly, it might also be possible to carry out the modification of the epoxy resin, chosen as the starting product, in a separate process.
However, a number of difficulties are attached to that process and, conse-quently, it is less advisable. ~or example, a special operation and, in most cases, a catalyst for a correct controlling of the modification with the mono-functional carboxylic acid and/or phenol are required. In most cases, this ~' , - . ...
.
catalyst must entircly be rcmove~ again together with the solvcnts tllat may have been used. This is no~ ollly onerous uu~ of~e~ uoes no; juccced in ~' a sufficient de~ree, as a result of which the toner powder preparccl with the resin thus modified will generally deteriorate quickly.
The toner powder according to thc invention can be prepared by means of one of the methods generally kno~ for the preparations of toner powders such as, for example, the kneadingJ extrusion or hot melt method.
According to the two fi.rst methods the resin, the polarity control agent, the colouring materials andJ if desired, other inaredients are generally mixed together at approximately 90 - 130C, according to the last-mentioned method this mixing generally occurs at roulld 200C. After cooling, the resulting mass is ground to particles of the deslred degree of fineness, in general between 2 and50~m.
Of the three manufacturing methods mentioned above the hot melt method has proved to be the most suitable one for the preparation of the .
toner powder according to the invention. The toner powder prepared according to that method even proves to be more satisfactory and to be reproducible to.
a higher degree, in particular with regard to its most essential properties such as charge behaviour, sta~ility and fusing behaviour, than wllen the two other methods are applied. Moreover, most polarity control agents and dyes dissolve sufficiently in the resin at temperatures round 200C, so that the homogeneous composition of the toner powder required foT the charge properties can be attained without the necessity of ma~ing special arrangements.
; However, toner powder according to the invention of satisfactory quality can also be obtained with the kneading and extrusion method, provided certain provisions are observed. The fact is that at temperatures at which these two mcthods generally are performed, namely, at approximately Y0 to 130C, the most conventional polarity control agents and dyes do not dissolve sufficiently in the resin to cffect the desired homogelleous mi~ture. This holds good in particular with regard to the preferred polarity control agents - 10 ~
"l "" "1~ f~ .
, S~
of the nigrosine type.
In such cases, successful use can be made of a sub-stance capable of promoting,the dissolution of the polarity con-trol agent, such as described in Applicant's-not pre~o~-~y ~ub-~e~e~ Dutch Application No. 7415325.
In general, the amounts to be used range between a few ; per cent and some tens of per cents.
Advisable, in particular, is the use of the diphenyl-phthalate or N-cyclohexyl-p-toluenesulphonamide referred to in said patent application.
Moreover, since the modification by intermolecular re-action of the epoxy groups of the epoxy resin chosen as a start-ing product proceeds relatively slowly at said temperatures, it is advisable, if the required modification of the epoxy groups is desirably to be effected only partly with the monofunctional - carboxylic acid and/or phenol, to combine the modification with cross-linking by means of a polyvalent epoxy hardener.
Although the use of the compounds, described in said Dutch Patent Application as dissolving accelerators, is in fact superfluous if the toner powder according to the invention is prepared by the hot melt method, for a number of reasons their use may nevertheless be also advantageous in that case. For ex-ample, their addition to the reaction mixture causes a decreased melting point of the toner powder ultimately obtained, and by that the possibility of also using, as starting product for the preparation of the toner powder according to the invention, epoxy resins of which the melting point is higher than 150C. It is also possible to use this addition in order to restore the melting ; point of the toner powder to its desired level9 if this should have become too high as a result of the major part of the epoxy ~ .
.. . : .
~$~
groups of the epoxy resin being modified by intermolecular re-action or cross-linking with a polyvalent epoxy hardener.
In addition to the modified epoxy resin or the mixture of modified epoxy resins the finely divided, coloured toner part-icles of the toner powder according to the present invention may contain other ingredients. The modified epoxy resin can be mixed, in particular, with a phenoxy resin such as, for example, ;~
Rutopox* 07-17, a product from Messrs. Bakelite. However, the ~
ratio modified epoxy resin: phenoxy resin should amount to at ~ m least 1:1, preferably to at least 1.5-1.75:1.
The addition of phenoxy resins, a generic term for amorphous poly (hydroxy-ethers) that have been derived from di- ;
phenols and epichlorohydrin and have a high molecular weight, ex-tends the fusing range of the toner particles. This affords the possibility, for example, of making a toner powder based on an epoxy resin, being exclusively or predominantly modified with a monofunctional carboxylic acid and/or phenol, also suitable for use in an apparatus equipped with a contact-fusing device.
To prepare a powder developer of the two-component type, the toner powder according to the invention is mixed, either immediately after its preparation or in a later stage, with the desired carrier particles. If the developer is intended for magnetic brush development magnetic iron particles, which may be provided with a surface layer, are used as carrier. The de-sired particle size of the carrier are known to those skilled in the art. In general, its dimensions range between 50 and 150 ~m.
Dependent on the particle size of the two components the two- ;
component developer generally contains from 1 to 8% by weight of toner particles. ;
The developers thus ob-tained can be used satisfactorily ~Trademark for the development of latent electrostatic images having a neg-ative charge, such as they are obtained, for example, on electro-photographic elements based on zinc oxide.
The invention is further illustrated with reference to the following Examples.
;
In a vessel, provided with a stirrer and an oil bath heating 468 g of the epoxy resin Epikote* 1006 (E.M.M.=1700, sup-plied by Shell) were gradually added at 200 C to a mixture of 36 g of nigrosine base (Colour Index third ed. No. 50415:1), 60 g of ~-cyclohexyl-p-toluenesulphonamide and 30 g of benzoic acid.
After mixing, the ingredients were fully dissolved in one an-other. Subsequently, 36 g of carbon were added and the whole was stirred for two hours at 200C, a proper dispersion of the carbon thus being achieved. The hot melt was then cooled down and ground and sieved in a way known by itself to a toner powder hav- -ing particles between 8 and 27 ~m. The E.M.M. oE the resin mod-ified with benzoic acid in the toner powder, which was determined in the way analogous to the method of analysis 2.3.2.7.2. prac-tised by the Synthetic Materials Institute T.NØ, Delft, exceeded ~ ;
40,000. The content of unreacted benzoic acid in the toner pow-der was smaller than 0.1%. Consequently, the resin had been mod- ~
ified for 90% with benzoic acid. The toner powder had a glass -transition temperature (Tg) of 56C. The Tg was determined from the D.S.C. thermogram recorded by a Du Pont 990 thermal analyzer.
Also after prolonged heating at 200C, a temperature which is well over the temperatures usually applied in fusing devices, the Tg remained constant at 56C, which shows that the toner thermally was stable.
Four parts by weight of the toner powder thus prepared *Trademark were properly mixed with 96 parts by weight of iron powder hav-ing particles between approximately 55 and 130 ~m. The toner powder in the developer so obtained had a pronounced positive polarity. The triboelectric charge amounted to ~13~C per gram toner powder. By means of this developer combined with a photo~
conductor based on zinc oxide as described in the Dutch Patent Application 7217484, first-class copies on plain paper were ob-tained in an automatically operating copying apparatus, permit-ting wide tolerances in adjusting its functions and the concen-tration of the toner. The toner powder also processed a verygood permanence during prolonged use in the copying apparatus.
In an endurance test, whereby the concentration of the toner in the developer was kept constant by adding extra toner powder, in order to compensate for the toner powder used in the copying process, copies of good quality were still obtained after a run of 40,000 prints. In a radiation fusing device - 13a -.~
as described in the Dutch Patent Application 7205491 the toner powder can be fixed rapidly and well onto paper at a set temperature of approximately 150C.
The toner powder could also be fixed in a contact-fusing device. The contact-fusing device used was fitted with a roller coated with silicone rubber, of which the top layer had been previously aged in a prolonged copying process.
Fusing ranges which were shorter but which corresponded more to practice than with the use of new silicone rubber were found. The effective contact time of the copy with the heated roller amounted to 1.3 seconds. The toner pow-der possessed a reasonable fusing range, namely, from 87 to 109C ~range length 22C). In that case the lower limit was the temperature at which the fusion of the toner powder was just sufficient, and the upper limit was the temperature at which the transfer of the molten toner powder to the silicone rubber set in.
The preparation according to Example 1 was repea*ed in batches of 630 g, 6.3 kg and 126 kg, respectively. The measuring and copying results of the toner powders thus obtained were practically identical to those described in Example 1, from which it may be concluded that the reproducibility of the preparation is good.
In a powder mixer a ground mixture of nigrosine base, N-cyclohexyl-p-toluenesulphonamide and benzoic acid was premixed at room temperature with Epikote*1006 and carbon in the ratios mentioned in Example 1. This mixture was then extruded in one operation in a laboratory double-screw extruder, model Davo M.S. 2.1, at a temperature of 150C in the kneading zones. The residence time was approximately 5 minutes. The cooled melt was processed to toner powder and examined in the way described in Example 1, resulting in practically equal results. These results, obtained after a preparation whereby the residence time and *emperature conditions were clearly different from those according to Example 1, illustrate a wide margin applicable in *Trade Mark - 1~ -.......
the useful preparing conditions.
According to the process described in Example 1, a hotmelt was prepared from 36 g of nigrosine base, 60 g of N-cyclo-hexyl-p-toluenesulphonamide, 416.8 g of Epikote* 1006, 36 g of carbon, but now with 51.2 g of the modification compound 4-(~
dimethylbenzyl) phenol (=p-cumylphenol, supplied by Fluka). After cooling down, grindîng and sieving, a toner powder having a part-icle size between 7 and 28 ~m was obtained. The E.M.M. of the modified epoxy resin was higher than 40,000. The modification rate was 100%. The Tg of the toner powder was 50C and remained constant after prolonged heating at 200 C.
In a developer prepared as in Example 1, the toner powder could be provided with a pronounced positive charge of 13 ~C/g. The toner powder did hardly dust during use, which points to a highly uniform charge distribution. An excellent image quality was obtained. The toner powder was eminently permanent ;
and could be fixed in a radiation fusing device at a set temper-ature of 145C. The contact fusing range was 81 to 107C (length 26C).
Using the above formula a toner powder was also pre-pared in an A.M.K. kneading mixer at an equilibrium temperature of appraximately 110C and a total residence time of 2 hours.
The E.M.M. of the modified resin thus obtained was 15,000. The Tg was 54 C and was still nearly unchanged after heating for some time at 200 C. The copying and fusing results were practically equal to those of the toner powder prepared according to the hot melt method.
EXAMPLE 5 `~
According to the process of Example 1, a hot melt was *Trademark ~ .
prepared from 36 g of nigrosine base, 30 g oE N-cyclohexyl-p-toluenesulphonamide, 406.6 g o~ Epikote* 1006, 36 g of car~on, but now with 61.4 g of the modification compound octadecanoic acid (equivalent mass = 285). After cooling, grinding and siev-ing a toner powder having a particle size between 8 and 32 ~Im was obtained. The Tg was 43 C and remained constant, also after heating for some time up to 200C. The E.M.M. of the modified resin was 40,000. The modification rate was 90%. In a developer prepared as in Example 1, the toner. powder could be provided with a pronounced positive charge of 14 ~C/g. It dusted very slightly.
A very good image quality was obtained. The toner powder was properly permanent, could be fixed in a radiation fusing device at 135C, and had a contact-fusing range of 75-98C (length 23 C).
In a reaction vessel as described in Example 1, 528 g of Epikote* 1004 (E.M.M. = 900), 36 g of nigrosine base and 66 g of benzoic acid were mixed for one hour at 200C. The ingredients thereby fully dissolved in one another. Subsequently, 36 g of carbon were added and stirring was continued for another hour at 200C. The cooled melt was ground and sieved to a toner powder ;
having particles between 8 and 24 ~m. The E.M.M. was 40,000.
Before and after heating at 200C the toner powder had a constant Tg value of 63 C. The charge of the toner powder in a 4 per cent developer was 11 ~C/g. A good image quality was obtained. The toner powder could be fixed onto paper at a temperature of 155C
in the radiant fusing device. The contact-fusing range was 87-103C (length 16C).
Example 1 was reworked, but now wlth 36 g oE nigrosine hydrochloride (Colour Index third ed. No. 50415) instead of the *Trademark ~: .
nigrosine base. The E.M.M. and constant Tg value of the toner powder were 40,000 and 66C, respectively. Satisfactory copying and fusing results were obtained.
Example l was reworked, but now with 31.9 g of 2-hydroxybenzoic acid instead of the benzoic acid, and with 436.1 g of Epikote* 1006. The modification rate was 90%. The E.M.M. and constant Tg value were 40,000 and 57C, respectively. Satisfact-ory copying and fusing results were obtained.
Example 1 was reworked, but now with 41.1 g of 3,4-dimethoxybenzoic acid instead of the benzoic acid, and with 426.9 g of Epikote* 1006. The modification rate was 90%. The E.M.M.
and constant Tg value were 40,000 and 57 C, respectively. Good copying and fusing results were obtained.
EXAMPLE 10 (Comparative Example) The preparation according to Example 1 was repeated, but now with the omission of the modification compound benzoic acid. The cooled melt could be ground only with difficulty and the toner powder obtained could not be fixed in the radiation fusing device under the scorch limit of the paper.
.. ~
According to the preparing method of Exa~ple l, a hot melt was prepared from 30 g of nigrosine base, 75 g of N-cyclo-hexyl-p-toluenesulphonamide 12.5 g of (4-~ dimethylbenzyl`-phenol, 352.5 g of Epikote* 1006 and 30 g of carbon. The E.M.M.
was 21,000. The rest of the unreacted modification compound was <0.1%. The Tg was 54 C and did not change after heating for 30 minutes at 200 C.
The modification rate effected by the phenol amounted *Trademark .~.f ~
:: ' ' ~ t~
to 30%. In a developer prepared in the manner described in Example 1 the toner powder prepared from the cooled melt and hav-ing a particle size between 7 and 31 ~m acquired a pronounced positive charge of 13 ~C/g. The toner powder yielded excellent copies in a copying apparatus, permitting wide tolerances in ad-justing its functions and the concentration oE the toner. In a radiation fusing device the toner powder could be fixed at a temperature of 155C. In the contact-fusing device described be-fore the fusing range was 88-121 C (length 33 C).
Analogous to the process of Example 1 a hot melt was -prepared from 36 g o~ nigrosine, 60 g of N-cyclohexyl-p-toluene-sulphonamide, 51.6 g of benzoic acid and 372 g of Epikote* 1004.
After mixing for one hour, the E.M.M. of the resin increased from ;
900 to 40,000 (90æ modification). Subsequently, 36 g of carbon and 96 g of Rutapox* 07-17 were added, and the stirring operation was continued for one hour at 220 C (Rutapox* 07-17 is a bis-phenol A-epichlorohydrin phenoxy resin with an average molecular weight of 25-30,000, supplied by Bakelite). The Tg of the mix-ture was 47C and remained constant after heating at 200C. The toner powder prepared from this mixture had a particle size dis-tribution between 9 and 28 ~m. The obtainable charge was 12 ~C/g. Excellent copies were obtained. The toner powder could be ~ -; fixed in a radiant fusing device at 145C, and had a wide contact-fusing range, namely, 79-114C (length 35 C).
- A comparable toner powder which contained no Rutapox*
07-17 but only modified Epikote* 1004 as a resin, had a contact-fusing range of 80-96 C (length 16 C).
In a powder mixer a ground mixture of 36 g of nigrosine `
*Trademark ;.j , base, 60 g of N-cyclohexyl-p-toluenesulphonamide, 9.7 g of ben-zoic acid and 9.3 g of succinic acid was premixed with 36 g of carbon and 449 g of Epikote* 1006. This mixture was then ex-truded at 160C. The residence time in the extruder was approx-imately 5 minutes. The mixture had a constant Tg value of 61C.
The E.M.M. was higher than 40,000. The modification rate with benzoic acid was 30%. The toner after being mixed with iron to a 4 per cent developer gave a good image quality, and had a wide contact-fusing range of 89-129C (length 40C).
In the manner of Example 1, 36 g of nigrosine base, 60 g of N-cyclohexyl-p-toluenesulphonamide, 468 g of Epikote*
1006 and 36 g of carbon were mixed for two hours at 200 C. Sub-sequently, a mixture of 6 g of nigrosine base, 10 g of N-cyclo-hexyl-p-toluenesulphonamide, 5.0 g of benzoic acid, 79 g of Epikote* 1006 and 6 g of carbon was added and stirred for another 30 minutes at 200 C. After cooling, grinding and sieving, a toner powder was obtained which, upon examination in the manner described in Example 1, gave a good copy quality with wide toler-ances in the toner/iron ratio and in setting the apparatus. The constant Tg value was 68 C; the E.M.M. was 40,000. The rate of epoxy resin modified with benzoic acid in the toner was 15%. The toner could be fixed well at a set temperature of 170 C in the radiant fusing device.
In the arrangement described before, the contact-fusing range was 99-148C (length 49 C).
Substantially in the same way as described in Example 1, a hot melt was prepared by heating, whilst continuously stir-ring, during one hour and at 200C a mixture of 341.6 g Epikote*
*Trademark 1001 (m.p. 60-70 C; Durrance; E.M.M. 450-500) 124.4 g (4-a,a-dimethylbenzyl)-phenol, 48.0 g nigrosine Base G.B., 48.0 g Printex G*.
The E.M.M. of the Epikote* 1001 appeared to have increased to 16,300. Subsequently, 240 g Rutapox* 07-17 were gradually added whilst maintaining the temperature at 200 C and continuously stirring. After approximately another hour the ; mixture was found to be completely homogeneous.
Then the mixture was cooled down, g~ound and sieved to a toner powder having particles between 8 and 25 ~m. The contact fusing range of this toner powder was ~rom 83 to 140C, which made it particularly useful for application in a developer for use in a copier equipped with a contact fusing device.
t~
*Trademark
heptanoic acid, nonanoic acid, dodecanoic and isododecanoic acid, hexadecanoic acid and octadecanoic acid.
Examples of the above phenolic compounds are 4-n-butyl phenol, 4-n-pentyl phenol, 2, 3, 4, 6-tetramethyl phenol, 2, 3, 5, 6-tetramethyl phenol, 4-~a,a-dimethyl) benzyl phenol, 4-cyclohexyl phenol, 3-methoxy phenol, 4-methoxy phenol and 4~ethoxy phenol.
Of the compounds mentioned above octadecanoic acid, subs~ituted or non-substituted benzoic acid and 4-~a,a-dimethyl) benzyl phenol are most preferably used.
The modification of the epoxy resin chosen as starting product to ~;
become the modified epoxy resin for use in the toner powder according to the invention preferably occurs during preparation of the toner powder itself.
Surprisingly it has appeared that in this way the modification process can be performed well and be controlled satisfactorily, so that in thls way a tailor-made toner powder of excellent quality can be obtained. Moreover, in that case no special catalyst or other additive is required for performing the modification with the monofunctional carboxylic acid and/or phenol satisfactorily, which is an additional advantage.
Admittedly, it might also be possible to carry out the modification of the epoxy resin, chosen as the starting product, in a separate process.
However, a number of difficulties are attached to that process and, conse-quently, it is less advisable. ~or example, a special operation and, in most cases, a catalyst for a correct controlling of the modification with the mono-functional carboxylic acid and/or phenol are required. In most cases, this ~' , - . ...
.
catalyst must entircly be rcmove~ again together with the solvcnts tllat may have been used. This is no~ ollly onerous uu~ of~e~ uoes no; juccced in ~' a sufficient de~ree, as a result of which the toner powder preparccl with the resin thus modified will generally deteriorate quickly.
The toner powder according to thc invention can be prepared by means of one of the methods generally kno~ for the preparations of toner powders such as, for example, the kneadingJ extrusion or hot melt method.
According to the two fi.rst methods the resin, the polarity control agent, the colouring materials andJ if desired, other inaredients are generally mixed together at approximately 90 - 130C, according to the last-mentioned method this mixing generally occurs at roulld 200C. After cooling, the resulting mass is ground to particles of the deslred degree of fineness, in general between 2 and50~m.
Of the three manufacturing methods mentioned above the hot melt method has proved to be the most suitable one for the preparation of the .
toner powder according to the invention. The toner powder prepared according to that method even proves to be more satisfactory and to be reproducible to.
a higher degree, in particular with regard to its most essential properties such as charge behaviour, sta~ility and fusing behaviour, than wllen the two other methods are applied. Moreover, most polarity control agents and dyes dissolve sufficiently in the resin at temperatures round 200C, so that the homogeneous composition of the toner powder required foT the charge properties can be attained without the necessity of ma~ing special arrangements.
; However, toner powder according to the invention of satisfactory quality can also be obtained with the kneading and extrusion method, provided certain provisions are observed. The fact is that at temperatures at which these two mcthods generally are performed, namely, at approximately Y0 to 130C, the most conventional polarity control agents and dyes do not dissolve sufficiently in the resin to cffect the desired homogelleous mi~ture. This holds good in particular with regard to the preferred polarity control agents - 10 ~
"l "" "1~ f~ .
, S~
of the nigrosine type.
In such cases, successful use can be made of a sub-stance capable of promoting,the dissolution of the polarity con-trol agent, such as described in Applicant's-not pre~o~-~y ~ub-~e~e~ Dutch Application No. 7415325.
In general, the amounts to be used range between a few ; per cent and some tens of per cents.
Advisable, in particular, is the use of the diphenyl-phthalate or N-cyclohexyl-p-toluenesulphonamide referred to in said patent application.
Moreover, since the modification by intermolecular re-action of the epoxy groups of the epoxy resin chosen as a start-ing product proceeds relatively slowly at said temperatures, it is advisable, if the required modification of the epoxy groups is desirably to be effected only partly with the monofunctional - carboxylic acid and/or phenol, to combine the modification with cross-linking by means of a polyvalent epoxy hardener.
Although the use of the compounds, described in said Dutch Patent Application as dissolving accelerators, is in fact superfluous if the toner powder according to the invention is prepared by the hot melt method, for a number of reasons their use may nevertheless be also advantageous in that case. For ex-ample, their addition to the reaction mixture causes a decreased melting point of the toner powder ultimately obtained, and by that the possibility of also using, as starting product for the preparation of the toner powder according to the invention, epoxy resins of which the melting point is higher than 150C. It is also possible to use this addition in order to restore the melting ; point of the toner powder to its desired level9 if this should have become too high as a result of the major part of the epoxy ~ .
.. . : .
~$~
groups of the epoxy resin being modified by intermolecular re-action or cross-linking with a polyvalent epoxy hardener.
In addition to the modified epoxy resin or the mixture of modified epoxy resins the finely divided, coloured toner part-icles of the toner powder according to the present invention may contain other ingredients. The modified epoxy resin can be mixed, in particular, with a phenoxy resin such as, for example, ;~
Rutopox* 07-17, a product from Messrs. Bakelite. However, the ~
ratio modified epoxy resin: phenoxy resin should amount to at ~ m least 1:1, preferably to at least 1.5-1.75:1.
The addition of phenoxy resins, a generic term for amorphous poly (hydroxy-ethers) that have been derived from di- ;
phenols and epichlorohydrin and have a high molecular weight, ex-tends the fusing range of the toner particles. This affords the possibility, for example, of making a toner powder based on an epoxy resin, being exclusively or predominantly modified with a monofunctional carboxylic acid and/or phenol, also suitable for use in an apparatus equipped with a contact-fusing device.
To prepare a powder developer of the two-component type, the toner powder according to the invention is mixed, either immediately after its preparation or in a later stage, with the desired carrier particles. If the developer is intended for magnetic brush development magnetic iron particles, which may be provided with a surface layer, are used as carrier. The de-sired particle size of the carrier are known to those skilled in the art. In general, its dimensions range between 50 and 150 ~m.
Dependent on the particle size of the two components the two- ;
component developer generally contains from 1 to 8% by weight of toner particles. ;
The developers thus ob-tained can be used satisfactorily ~Trademark for the development of latent electrostatic images having a neg-ative charge, such as they are obtained, for example, on electro-photographic elements based on zinc oxide.
The invention is further illustrated with reference to the following Examples.
;
In a vessel, provided with a stirrer and an oil bath heating 468 g of the epoxy resin Epikote* 1006 (E.M.M.=1700, sup-plied by Shell) were gradually added at 200 C to a mixture of 36 g of nigrosine base (Colour Index third ed. No. 50415:1), 60 g of ~-cyclohexyl-p-toluenesulphonamide and 30 g of benzoic acid.
After mixing, the ingredients were fully dissolved in one an-other. Subsequently, 36 g of carbon were added and the whole was stirred for two hours at 200C, a proper dispersion of the carbon thus being achieved. The hot melt was then cooled down and ground and sieved in a way known by itself to a toner powder hav- -ing particles between 8 and 27 ~m. The E.M.M. oE the resin mod-ified with benzoic acid in the toner powder, which was determined in the way analogous to the method of analysis 2.3.2.7.2. prac-tised by the Synthetic Materials Institute T.NØ, Delft, exceeded ~ ;
40,000. The content of unreacted benzoic acid in the toner pow-der was smaller than 0.1%. Consequently, the resin had been mod- ~
ified for 90% with benzoic acid. The toner powder had a glass -transition temperature (Tg) of 56C. The Tg was determined from the D.S.C. thermogram recorded by a Du Pont 990 thermal analyzer.
Also after prolonged heating at 200C, a temperature which is well over the temperatures usually applied in fusing devices, the Tg remained constant at 56C, which shows that the toner thermally was stable.
Four parts by weight of the toner powder thus prepared *Trademark were properly mixed with 96 parts by weight of iron powder hav-ing particles between approximately 55 and 130 ~m. The toner powder in the developer so obtained had a pronounced positive polarity. The triboelectric charge amounted to ~13~C per gram toner powder. By means of this developer combined with a photo~
conductor based on zinc oxide as described in the Dutch Patent Application 7217484, first-class copies on plain paper were ob-tained in an automatically operating copying apparatus, permit-ting wide tolerances in adjusting its functions and the concen-tration of the toner. The toner powder also processed a verygood permanence during prolonged use in the copying apparatus.
In an endurance test, whereby the concentration of the toner in the developer was kept constant by adding extra toner powder, in order to compensate for the toner powder used in the copying process, copies of good quality were still obtained after a run of 40,000 prints. In a radiation fusing device - 13a -.~
as described in the Dutch Patent Application 7205491 the toner powder can be fixed rapidly and well onto paper at a set temperature of approximately 150C.
The toner powder could also be fixed in a contact-fusing device. The contact-fusing device used was fitted with a roller coated with silicone rubber, of which the top layer had been previously aged in a prolonged copying process.
Fusing ranges which were shorter but which corresponded more to practice than with the use of new silicone rubber were found. The effective contact time of the copy with the heated roller amounted to 1.3 seconds. The toner pow-der possessed a reasonable fusing range, namely, from 87 to 109C ~range length 22C). In that case the lower limit was the temperature at which the fusion of the toner powder was just sufficient, and the upper limit was the temperature at which the transfer of the molten toner powder to the silicone rubber set in.
The preparation according to Example 1 was repea*ed in batches of 630 g, 6.3 kg and 126 kg, respectively. The measuring and copying results of the toner powders thus obtained were practically identical to those described in Example 1, from which it may be concluded that the reproducibility of the preparation is good.
In a powder mixer a ground mixture of nigrosine base, N-cyclohexyl-p-toluenesulphonamide and benzoic acid was premixed at room temperature with Epikote*1006 and carbon in the ratios mentioned in Example 1. This mixture was then extruded in one operation in a laboratory double-screw extruder, model Davo M.S. 2.1, at a temperature of 150C in the kneading zones. The residence time was approximately 5 minutes. The cooled melt was processed to toner powder and examined in the way described in Example 1, resulting in practically equal results. These results, obtained after a preparation whereby the residence time and *emperature conditions were clearly different from those according to Example 1, illustrate a wide margin applicable in *Trade Mark - 1~ -.......
the useful preparing conditions.
According to the process described in Example 1, a hotmelt was prepared from 36 g of nigrosine base, 60 g of N-cyclo-hexyl-p-toluenesulphonamide, 416.8 g of Epikote* 1006, 36 g of carbon, but now with 51.2 g of the modification compound 4-(~
dimethylbenzyl) phenol (=p-cumylphenol, supplied by Fluka). After cooling down, grindîng and sieving, a toner powder having a part-icle size between 7 and 28 ~m was obtained. The E.M.M. of the modified epoxy resin was higher than 40,000. The modification rate was 100%. The Tg of the toner powder was 50C and remained constant after prolonged heating at 200 C.
In a developer prepared as in Example 1, the toner powder could be provided with a pronounced positive charge of 13 ~C/g. The toner powder did hardly dust during use, which points to a highly uniform charge distribution. An excellent image quality was obtained. The toner powder was eminently permanent ;
and could be fixed in a radiation fusing device at a set temper-ature of 145C. The contact fusing range was 81 to 107C (length 26C).
Using the above formula a toner powder was also pre-pared in an A.M.K. kneading mixer at an equilibrium temperature of appraximately 110C and a total residence time of 2 hours.
The E.M.M. of the modified resin thus obtained was 15,000. The Tg was 54 C and was still nearly unchanged after heating for some time at 200 C. The copying and fusing results were practically equal to those of the toner powder prepared according to the hot melt method.
EXAMPLE 5 `~
According to the process of Example 1, a hot melt was *Trademark ~ .
prepared from 36 g of nigrosine base, 30 g oE N-cyclohexyl-p-toluenesulphonamide, 406.6 g o~ Epikote* 1006, 36 g of car~on, but now with 61.4 g of the modification compound octadecanoic acid (equivalent mass = 285). After cooling, grinding and siev-ing a toner powder having a particle size between 8 and 32 ~Im was obtained. The Tg was 43 C and remained constant, also after heating for some time up to 200C. The E.M.M. of the modified resin was 40,000. The modification rate was 90%. In a developer prepared as in Example 1, the toner. powder could be provided with a pronounced positive charge of 14 ~C/g. It dusted very slightly.
A very good image quality was obtained. The toner powder was properly permanent, could be fixed in a radiation fusing device at 135C, and had a contact-fusing range of 75-98C (length 23 C).
In a reaction vessel as described in Example 1, 528 g of Epikote* 1004 (E.M.M. = 900), 36 g of nigrosine base and 66 g of benzoic acid were mixed for one hour at 200C. The ingredients thereby fully dissolved in one another. Subsequently, 36 g of carbon were added and stirring was continued for another hour at 200C. The cooled melt was ground and sieved to a toner powder ;
having particles between 8 and 24 ~m. The E.M.M. was 40,000.
Before and after heating at 200C the toner powder had a constant Tg value of 63 C. The charge of the toner powder in a 4 per cent developer was 11 ~C/g. A good image quality was obtained. The toner powder could be fixed onto paper at a temperature of 155C
in the radiant fusing device. The contact-fusing range was 87-103C (length 16C).
Example 1 was reworked, but now wlth 36 g oE nigrosine hydrochloride (Colour Index third ed. No. 50415) instead of the *Trademark ~: .
nigrosine base. The E.M.M. and constant Tg value of the toner powder were 40,000 and 66C, respectively. Satisfactory copying and fusing results were obtained.
Example l was reworked, but now with 31.9 g of 2-hydroxybenzoic acid instead of the benzoic acid, and with 436.1 g of Epikote* 1006. The modification rate was 90%. The E.M.M. and constant Tg value were 40,000 and 57C, respectively. Satisfact-ory copying and fusing results were obtained.
Example 1 was reworked, but now with 41.1 g of 3,4-dimethoxybenzoic acid instead of the benzoic acid, and with 426.9 g of Epikote* 1006. The modification rate was 90%. The E.M.M.
and constant Tg value were 40,000 and 57 C, respectively. Good copying and fusing results were obtained.
EXAMPLE 10 (Comparative Example) The preparation according to Example 1 was repeated, but now with the omission of the modification compound benzoic acid. The cooled melt could be ground only with difficulty and the toner powder obtained could not be fixed in the radiation fusing device under the scorch limit of the paper.
.. ~
According to the preparing method of Exa~ple l, a hot melt was prepared from 30 g of nigrosine base, 75 g of N-cyclo-hexyl-p-toluenesulphonamide 12.5 g of (4-~ dimethylbenzyl`-phenol, 352.5 g of Epikote* 1006 and 30 g of carbon. The E.M.M.
was 21,000. The rest of the unreacted modification compound was <0.1%. The Tg was 54 C and did not change after heating for 30 minutes at 200 C.
The modification rate effected by the phenol amounted *Trademark .~.f ~
:: ' ' ~ t~
to 30%. In a developer prepared in the manner described in Example 1 the toner powder prepared from the cooled melt and hav-ing a particle size between 7 and 31 ~m acquired a pronounced positive charge of 13 ~C/g. The toner powder yielded excellent copies in a copying apparatus, permitting wide tolerances in ad-justing its functions and the concentration oE the toner. In a radiation fusing device the toner powder could be fixed at a temperature of 155C. In the contact-fusing device described be-fore the fusing range was 88-121 C (length 33 C).
Analogous to the process of Example 1 a hot melt was -prepared from 36 g o~ nigrosine, 60 g of N-cyclohexyl-p-toluene-sulphonamide, 51.6 g of benzoic acid and 372 g of Epikote* 1004.
After mixing for one hour, the E.M.M. of the resin increased from ;
900 to 40,000 (90æ modification). Subsequently, 36 g of carbon and 96 g of Rutapox* 07-17 were added, and the stirring operation was continued for one hour at 220 C (Rutapox* 07-17 is a bis-phenol A-epichlorohydrin phenoxy resin with an average molecular weight of 25-30,000, supplied by Bakelite). The Tg of the mix-ture was 47C and remained constant after heating at 200C. The toner powder prepared from this mixture had a particle size dis-tribution between 9 and 28 ~m. The obtainable charge was 12 ~C/g. Excellent copies were obtained. The toner powder could be ~ -; fixed in a radiant fusing device at 145C, and had a wide contact-fusing range, namely, 79-114C (length 35 C).
- A comparable toner powder which contained no Rutapox*
07-17 but only modified Epikote* 1004 as a resin, had a contact-fusing range of 80-96 C (length 16 C).
In a powder mixer a ground mixture of 36 g of nigrosine `
*Trademark ;.j , base, 60 g of N-cyclohexyl-p-toluenesulphonamide, 9.7 g of ben-zoic acid and 9.3 g of succinic acid was premixed with 36 g of carbon and 449 g of Epikote* 1006. This mixture was then ex-truded at 160C. The residence time in the extruder was approx-imately 5 minutes. The mixture had a constant Tg value of 61C.
The E.M.M. was higher than 40,000. The modification rate with benzoic acid was 30%. The toner after being mixed with iron to a 4 per cent developer gave a good image quality, and had a wide contact-fusing range of 89-129C (length 40C).
In the manner of Example 1, 36 g of nigrosine base, 60 g of N-cyclohexyl-p-toluenesulphonamide, 468 g of Epikote*
1006 and 36 g of carbon were mixed for two hours at 200 C. Sub-sequently, a mixture of 6 g of nigrosine base, 10 g of N-cyclo-hexyl-p-toluenesulphonamide, 5.0 g of benzoic acid, 79 g of Epikote* 1006 and 6 g of carbon was added and stirred for another 30 minutes at 200 C. After cooling, grinding and sieving, a toner powder was obtained which, upon examination in the manner described in Example 1, gave a good copy quality with wide toler-ances in the toner/iron ratio and in setting the apparatus. The constant Tg value was 68 C; the E.M.M. was 40,000. The rate of epoxy resin modified with benzoic acid in the toner was 15%. The toner could be fixed well at a set temperature of 170 C in the radiant fusing device.
In the arrangement described before, the contact-fusing range was 99-148C (length 49 C).
Substantially in the same way as described in Example 1, a hot melt was prepared by heating, whilst continuously stir-ring, during one hour and at 200C a mixture of 341.6 g Epikote*
*Trademark 1001 (m.p. 60-70 C; Durrance; E.M.M. 450-500) 124.4 g (4-a,a-dimethylbenzyl)-phenol, 48.0 g nigrosine Base G.B., 48.0 g Printex G*.
The E.M.M. of the Epikote* 1001 appeared to have increased to 16,300. Subsequently, 240 g Rutapox* 07-17 were gradually added whilst maintaining the temperature at 200 C and continuously stirring. After approximately another hour the ; mixture was found to be completely homogeneous.
Then the mixture was cooled down, g~ound and sieved to a toner powder having particles between 8 and 25 ~m. The contact fusing range of this toner powder was ~rom 83 to 140C, which made it particularly useful for application in a developer for use in a copier equipped with a contact fusing device.
t~
*Trademark
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A positively chargeable toner powder characterized by stability at temperatures up to 50°C and a melting point of about 65 to 150°C, which comprises finely divided toner particles containing an insulating thermoplastie resin, colouring materials, and a polarity control agent, the thermoplastic resin including at least 50% by weight of a modified epoxy resin having an epoxy molar mass (grams resin/grams equivalent of epoxy) of at least 10,000, at least 5% of epoxy groups of the modified epoxy resin modified with a monofunctional carboxylic acid and/or a mono-functional phenol by reaction with the respective carboxyl or hydroxyl groups thereof, and optionally, no more than 95% of epoxy groups of the modified epoxy resin modified by intermolecular reaction and/or by cross-linking with a polyfunctional epoxy hardener.
2. A toner powder according to claim 1, wherein the monofunctional carboxylic acid is a substituted or non-substituted, saturated aliphatic carboxylic acid.
3. A toner powder according to claim 2, wherein the monofunctional carboxylic acid is oetadeconoic acid.
4. A toner powder according to claim 1, wherein the monofunctional carboxylic acid is a substituted or non-substituted benzoic acid.
5. A toner powder according to claim 1, 2 or 4, wherein the mono-functional carboxylic acid and/or phenol is substituted by at least one alkyl, aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy, or aryloxy group.
6. A toner powder according to claim 1, wherein the monofunctional phenol is 4-(.alpha.,.alpha.-dimethylbenzyl)-phenol.
7. A toner powder according to claim 1, wherein the thermoplastic resin further includes N-cyclohexyl-p-toluenesulphonamide.
8. A toner powder according to claim 1, wherein the thermoplastic resin consists of up to 50% phenoxy resin.
9. A toner powder according to claim 1, wherein the modified epoxy resin is prepared from an epoxy resin of lower epoxy molar mass by reaction of at least 5% of its epoxy groups with a monofunctional carboxylic acid and/or monofunctional phenol at a temperature of about 130 - 250°C, with the proviso that during the reaction, the carboxylic acid and phenol are substantially nonvolatile and have no substitutents which are reactive towards the epoxy groups other than the respective carboxyl and hydroxy groups, and optionally, by reaction of no more than 95% of its epoxy groups by intermolecular reaction and/or by cross-linking with a poly-functional epoxy hardener.
10. A toner powder according to claim 9, wherein the thermoplastic resin comprises 60 - 70% by weight of an epoxy resin having an epoxy molar mass of 16,000 - 16,500 obtained by modifying an epoxy resin having a melting point between 60 and 70°C and an epoxy molar mass between 450 and 500 with (4-.alpha.,.alpha.-dimethylbenzyl)-phenol, and 40 - 30% by weight of a phenoxy resin with an average molecular weight of 25,000 - 30,000.
11. A process for preparing a positively chargeable toner powder according to claim 1, which comprises the steps of homogeneously mixing the thermoplastic resin in a molten state with the polarity control agent and colouring materials, cooling the mass thus obtained and grinding said cooled mass to the desired degree of fineness, wherein epoxy groups of an epoxy resin of lower epoxy molar mass chosen as starting material are modified with the monofunctional carboxylic acid and/or phenol during said mixing of the ingredients.
12. A process according to claim 11, wherein modification during said mixing of ingredients is also achieved by inter-molecular reaction and/or cross-linking with the polyfunctional hardener.
13. A process according to claim 11 or 12, wherein the mixing and modification is achieved at temperatures between approximately 150 and 250°C.
14. A two-component developer which comprises carrier particles and a toner powder according to claim 1.
15. A process for preparing toner powder for the development of electrostatic images according to claim 1, comprising adding into molten thermoplastic resin consisting predominantly of a starting epoxy resin, having an epoxy molar mass well below 10, 000, colouring material, a polarity control agent, and a monofunctional reactant consisting of non-substituted and substituted monofunctional carboxylic acids and/or non-substituted and substituted monofunctional phenols in an amount sufficient to react with at least 50% of the epoxy groups of said resin, and, optionally, epoxy resin hardener in amount to react with not more than 40% of said epoxy groups;
mixing said resin in molten state homogeneously with the added ingredients at a temperature of between 90 and 250°C until at least such a percentage of said epoxy groups are modified by reaction with said monofunctional reactant and, optionally, by intermolecular reaction and/or with the aid of a polyfunctional epoxy hardener, so that the epoxy molar mass of the starting epoxy resin has increased to at least 10,000;
cooling the reaction mixture; and grinding the cooled reaction mixture to the desired degree of particle fineness.
mixing said resin in molten state homogeneously with the added ingredients at a temperature of between 90 and 250°C until at least such a percentage of said epoxy groups are modified by reaction with said monofunctional reactant and, optionally, by intermolecular reaction and/or with the aid of a polyfunctional epoxy hardener, so that the epoxy molar mass of the starting epoxy resin has increased to at least 10,000;
cooling the reaction mixture; and grinding the cooled reaction mixture to the desired degree of particle fineness.
16. A process according to claim 15, wherein a quaternary ammonium compound as polarity control agent is present in the resin during said mixing.
17. A process according to claim 15 or 16, said monofunctional reactant being a substituted or non-substituted benzoic acid or 4-(.alpha.,.alpha.-dimethyl-benzyl) phenol.
18. A process according to claim 15 or 16, said monofunctional reactant being added in an amount sufficient to react with at least 50% of said epoxy groups and an epoxy resin hardener being added in an amount sufficient to react with between 5 and 40% of said epoxy groups.
19. A process according to claim 15 or 16, said monofunctional reactant being added in an amount sufficient to react with not more than 60% of said epoxy groups and a substantial proportion but not more than 30% of said epoxy groups being reacted by intermolecular reaction-and/or with a poly-functional epoxy resin hardener.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7605372A NL7605372A (en) | 1976-05-20 | 1976-05-20 | TONER POWDER FOR DEVELOPING ELECTROSTATIC IMAGES. |
| NL7605372 | 1976-05-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1115582A true CA1115582A (en) | 1982-01-05 |
Family
ID=19826226
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,802A Expired CA1115582A (en) | 1976-05-20 | 1977-05-05 | Toner powder containing an epoxy resin with epoxy groups modified by reaction with a monofunctional carboxylic acid and/or a monofunctional phenol |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS609264B2 (en) |
| AT (1) | AT357866B (en) |
| AU (1) | AU505953B2 (en) |
| BE (1) | BE854860A (en) |
| CA (1) | CA1115582A (en) |
| CH (1) | CH626731A5 (en) |
| DE (1) | DE2722974C2 (en) |
| DK (1) | DK150720C (en) |
| ES (1) | ES458636A1 (en) |
| FR (1) | FR2352326A1 (en) |
| GB (1) | GB1550555A (en) |
| IT (1) | IT1082763B (en) |
| NL (1) | NL7605372A (en) |
| NO (1) | NO145214C (en) |
| SE (1) | SE435765B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7810502A (en) * | 1978-10-20 | 1980-04-22 | Oce Van Der Grinten Nv | TONER POWDER FOR DEVELOPING ELECTROSTATIC IMAGES. |
| NL7711623A (en) * | 1977-10-24 | 1979-04-26 | Oce Van Der Grinten Nv | TONER POWDER FOR DEVELOPING LATENT ELECTROSTATIC IMAGES. |
| JPS54133346A (en) * | 1978-04-07 | 1979-10-17 | Mitsubishi Petrochemical Co | Toner for electrostatic latent image development |
| JPS5722248A (en) * | 1980-07-15 | 1982-02-05 | Mitsubishi Chem Ind Ltd | Electrostatic developing toner |
| JPS58181057A (en) * | 1982-04-19 | 1983-10-22 | Mitsubishi Chem Ind Ltd | Electrophotogaphic toner composition |
| DE3475524D1 (en) * | 1983-06-03 | 1989-01-12 | Shell Int Research | Novel polyglycidyl ethers, their preparation and their use as thermosetting coating compositions |
| BR8507103A (en) * | 1984-12-04 | 1987-03-31 | Dow Chemical Co | THERMALLY STABLE THERMOPLASTIC RESIN |
| JP3867900B2 (en) * | 2002-03-20 | 2007-01-17 | 株式会社リコー | Toner for electrophotography |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3907693A (en) * | 1973-05-21 | 1975-09-23 | Rank Xerox Ltd | Liquid developer for electrophotography |
| BE806408A (en) * | 1973-10-23 | 1974-04-23 | Oce Van Der Grinten Nv | TONER POWDER FOR DEVELOPING ELECTROSTATIC IMAGES |
-
1976
- 1976-05-20 NL NL7605372A patent/NL7605372A/en not_active Application Discontinuation
-
1977
- 1977-04-07 AU AU24069/77A patent/AU505953B2/en not_active Expired
- 1977-04-15 JP JP52044016A patent/JPS609264B2/en not_active Expired
- 1977-04-28 NO NO77771488A patent/NO145214C/en unknown
- 1977-04-29 CH CH534577A patent/CH626731A5/en not_active IP Right Cessation
- 1977-05-05 CA CA277,802A patent/CA1115582A/en not_active Expired
- 1977-05-10 ES ES458636A patent/ES458636A1/en not_active Expired
- 1977-05-12 GB GB20005/77A patent/GB1550555A/en not_active Expired
- 1977-05-17 SE SE7705868A patent/SE435765B/en not_active IP Right Cessation
- 1977-05-18 DK DK218577A patent/DK150720C/en not_active IP Right Cessation
- 1977-05-19 IT IT68152/77A patent/IT1082763B/en active
- 1977-05-20 FR FR7715523A patent/FR2352326A1/en active Granted
- 1977-05-20 AT AT364777A patent/AT357866B/en not_active IP Right Cessation
- 1977-05-20 DE DE2722974A patent/DE2722974C2/en not_active Expired
- 1977-05-20 BE BE177760A patent/BE854860A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JPS609264B2 (en) | 1985-03-08 |
| JPS52143025A (en) | 1977-11-29 |
| NO145214B (en) | 1981-10-26 |
| SE435765B (en) | 1984-10-15 |
| FR2352326B1 (en) | 1982-04-16 |
| FR2352326A1 (en) | 1977-12-16 |
| DE2722974C2 (en) | 1986-04-10 |
| ATA364777A (en) | 1979-12-15 |
| BE854860A (en) | 1977-11-21 |
| DE2722974A1 (en) | 1977-12-01 |
| DK218577A (en) | 1977-11-21 |
| CH626731A5 (en) | 1981-11-30 |
| NL7605372A (en) | 1977-11-22 |
| DK150720C (en) | 1987-12-21 |
| AT357866B (en) | 1980-08-11 |
| SE7705868L (en) | 1977-11-21 |
| IT1082763B (en) | 1985-05-21 |
| NO145214C (en) | 1982-02-03 |
| AU505953B2 (en) | 1979-12-06 |
| NO771488L (en) | 1977-11-22 |
| DK150720B (en) | 1987-06-01 |
| AU2406977A (en) | 1978-10-12 |
| GB1550555A (en) | 1979-08-15 |
| ES458636A1 (en) | 1978-02-01 |
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