DEVELOPER COMPOSITIONS

Abstract: A developer composition is disclosed which is characte­ rized by containing two incompatible resinous materials, one having a polar functional group and a glass transition temperature below 0°C, and the other having a polar functional group capable of interacting with the polar functional group of the one material and a glass transition temperature higher than 40°C. The developer may also contain 20-80% by weight of a fine magnetic powder. Images formed from the developer composition can be fixed to a suitable substrate by the application of only force.

Description: Developer Compositions This invention relates to a developer composition for a dry system for developing electrostatic latent images in electrophotography, electrostatic recording, etc., and more particularly to a developer composition having a pressure-fixing property. The process of forming electrostatic latent images is well known. For example, in an electrophotographic process after the usual charging of the photoconductive layer, it is exposed to a light image based on an original to reduce or eleminate electrostatic charge in the exposed areas, whereby an electrostatic latent image is formed. The latent image is then developed by a developer called a "toner". As is well-known, the development process can use either a liquid or a dry developer. The latter process may be further classified into a two-component development process, using two kinds of particles, carrier and toner, and a onecomponent development process, using a toner only. If necessary, the developed image is transferred onto a material such as paper. Thereafter, the toner is fixed on the paper by fusing the toner with heat or by softening a binding resin of the toner with a solvent, or by deforming the toner with only pressure. A pressure-fixing process has various merits with respect to energy saving, pollution and fire prevention as well as not requiring preheating for the fixing means. Other advantages are also obtained as compared with other fixing processes. Fowever, these advantages have to be offset against other considerations, such as the strength of the fixed toner image, the producibility of the toner, antiblocking property, impact resistance, i.e. as one property is improved others are made worse. Therefore, it is very difficult to improve all these properties simultaneously. Many suggestions have been made in order to overcome these difficulties. For example, Japanese Patent Publication No. 9880/69 proposes a toner containing an aliphatic component having 6-25 carbon atoms, and Japanese published Patent Application 119231/77 proposes a toner containing a crystalline wax and an ethylene-vinyl acetate copolymer. Known wax-like materials may be excellent with respect to deformability by pressure. However, the strength of the fixed image is weak and hence the image readily comes off or smears when it is rubbed. Furthermore, the toner is liable to attach to the surface of a photoconductive material, or to the surfaces of carrier particles when such a toner is used for a two-component type developer. This results in deterioration and changes in the characteristics of the carrier. Furthermore, when a crystalline resin such as polyethylene is used as a main binding resin for a toner, the producibility of the toner is reduced and a toner having stable characteristics is not obtained since it is difficult to control the degree of crystallization and the crystal form. Japanese published Patent Applications 75033/73 and 78931173 propose a material designed to meet the above requirements by using a block copolymer composed of hard and soft resins. However, if the amount of the soft component is increased to the extent necessary to impart sufficient pressure deformability to the toner, grinding of the toner becomes difficult when preparing a toner powder by a kneading and grinding method. When a toner powder is prepared by a spray drying method, this difficulty does not occur since a grinding step is unnecessary. However, liquid preparation becomes difficult and it is difficult to impart both a good fixing property and anti-blocking property to the toner obtained. Furthermore, when preparing a toner by any process, the use of a multi-phase polymer, such as a block copolymer or a graft copolymer, is disadvantageous in that it is difficult to control the multi-phase structure. More specifically, it is difficult to control the morphology of the toner as in the case of the aforesaid crystalline polymer. The morphology of the toner is greatly influenced by a slight change in the production conditions and the properties of raw materials, resulting in great changes in the characteristics of the toner. Japanese published Patent Application 87042/76 discloses an attempt to improve the pressure fixibility of a toner by blending a crystalline resin such as polyethylene wax as a main component with a small amount of material such as a vinylic resin. Hower, since a crystalline resin is used as the main binding resin, there exist the above-mentioned difficulties which are specific to the crystalline resin. When one resin is blended with another resin having good compatability therewith it is not possible to obtain a toner having alloptimum properties. On the other hand, when resins incompatible with each other are blended, it is not possible to mix the resins uniformly and slight changes in the production conditions result in the formation of toner having incompatible resins in a non-uniform dispersion. Furthermore, the fluidity and electrical characteristics of the toner are greatly reduced. Therefore, when using a conventional material compositions it is not possible to obtain a pressure-fixing toner having optimum properties. Furthermore, it is difficult to stably produce such a toner. The present invention aims at producing a developer composition having an excellent pressure-fixing property. To this end the present invention provides a developer composition comprising (A) a resinous material having a polar fuctional group and a glass transition temperature below OOC, and (B) a resinous material having a glass transition temperature above 400C, which is chemically incompatible with material (A). Material (B) has a polar functional group capable of interacting with the polar functional group of material (A). Materials (A) and (B) are indispensable components for the toner of this invention. Preferred results can be obtained using as material (A) an olefinic polymer having a hydroxy group, a carboxyl group or a carbonyl group and as material (B) a styrenic polymer or a polyester resin having a hydroxy group, a carboxyl group or a dialkylamino group. The invention will be explained below in detail. Firstly, the binding resinous material (A) in the developer composition of the present invention includes those having a glass transition temperature below 0 0C, preferably below -300C. Material (A) is selected from resinous materials which show plastic deformation or viscoelastic deformation with a pressure of less than about 2 kg/sq mm at room temperature and has a polar functional group. Polar functional groups of material (A) include a hydroxy group, a carbonyl group, a carboxy group, an epoxy group, a glicidyl group, a nitro group, a sulfonic acid group, an amino group, an amido group, a cyano group, an isocyanate group, a diazonium group, an aziridine group, an aldehyde group, an acid annydride, a methylol group, a thiol group, a mercapto group, a phosphoric acid group, and a halogen-containing group. These functional groups may be substituted by a group such as a methyl group, ethyl group, phenyl group or may have an ether linkage, ester linkage, etc. Among these groups, a hydroxy group, a carboxyl group and a carbonyl group are preferred, because they are very stable, have no deleterious effect on the characteristics of a toner, and have a large interaction with material (B). The resinous material (A) which has a polar functional group and which is capable of being deformed by pressure at normal temperature may be synthetic or natural resinous material. Examples of such materials include higher fatty acids (e.g. stearic acid, oleic acid, etc.,) and derivatives therof (e.g. fatty acid amides), chlorinated paraffin, chlorinated polyethylene, chlorinated polypropylene, oxidized polyethylene, polypropylene oxide, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, organic acid graft polyethylene, rubber-like acrylic acid copolymer, polyvinyl acetate, polyvinyl butyral, silicone and modified resins thereof, polycarbonate, fluorinated rubber, fluorinated wax, nitrile rubber, chloroprene rubber, polyamide, polyester, polyether, polyurethane, and polyalkyd. Of these, oxidized polyethylene, ethylene-acrylic acid copolymer and organic acid graft polyethylene, which have a hydroxy group, a carboxyl group or a carbonyl group are particularly preferred for material (A). Binding resinous material (B) in the developer composition of the present invention can be selected from natural and synthetic resinous materials having a glass transition temperature above 400C, more preferably 60-800C, and having a polar functional group as defined for material (A). A hydroxy group, a carboxyl group and dialkylamino group are particularly preferred as the polar functional group of material (B). In particular, styrene-acrylic acid copolymer, epoxy resin, phenol resin, polyester resin, etc., satisfying the aforesaid factors are preferably used since they meet many required parameters for toner. Material (A) is chemically incompatible with material (B) and the polar functional group of material (A) must interact with the polar functional group of material (B). Solubility is a suitable parameter for compatibility. With respect to this invention, when the parameter of the solubility of material (A) is taken as,RA and the parameter of the solubility of material (B) is taken as & ' whenl,ÇA- & is higher than about 0.5 it is defined as being incompatible. jhe solubility parameters of the resinous materials can be obtained by calculation. However, standard values which can be relied on are disclosed in "Polymer Handbook", 2nd Ed. (John Wiley & Sons). The interaction of the functional groups may involve (1) hydrophobic bonding, (2) electrostatic bonding, (3) hydrogen bonding, (4) charge transfer bonding, and (5) covalent bonding interactions. However, since the interactions polar functional groups is important in this invention, the interaction of (2) to (5) are of greater importance. With consideration to the factor explained above it should be understood that many combinations of materials (A) and (B) are possible in this invention. However, preferred materials which meet various electric, mechanical, rheological, thermal, optical and chemical properties required for a toner, include the combination of an olefinic polymer having group -OH, -COOH or C=O as material (A), and a styrenic copolymer or de-natured resin thereof, or a polyester resin each having group -OH, -COOH or -NR1R2 wherein R1 and R2, which may be the same or different, each represents an alkyl group (e.g., methyl, ethyl), as material (B). The interaction between an alcoholic -OH group and an acid -COOH group is particularly preferred for the prupose of the present invention. Most preferred combinations of material (A) and (B) are given in Table 1 below. Table 1 Material (A) Material (B) oxidized polyethylene styrene-allyl alcohol copolymer organic acid graft polyethylene ethylene-acrylic acid copolymer ethylene-vinyl acetate styrene-(meth)acrylic acid copolymer copolymer oxidized polyethylene styrene-dimethylaminoethyl methacrylate copolymer organic acid graft polyethylene " hydroxy graup-containing aromatic polyester For example, if polyethylene is considered as a base for the olefinic polymer, whose solubility parameter is about 8.0 as compared with about 9.0 for the solubility parameter of polystyrene which is one of the base resins for material (B), it will be understood that both materials are essentially incompatible with each other. There is no particular restriction regarding the position of the polar functional group in both materials (A) and (B). However, the materials having the polar functional group on the side chain or the end of the molecular chain are readily utilizable. With respect to the content of the functional group, when, for example a -COOH is present, the acid value is higher than 5 in both materials (A) and (B). Other polar group contents are similar in this regard. However, considerable care must be taken so that the content of the functional group is not too high. If the content gets too high, the interaction or reaction between the same kinds of molecules or different kinds of molecules as well as the intramolecular interaction or reaction become too strong. This can cause difficulties. Usually, when the functional group is -COOH, a resin having an acid value of from about 10 to about 100 is preferred. The acid value is shown by the number of milligrams of potassium hydroxide necessary for neutralizing the acid contained in one gram of the resin. It has hitherto been attempted to introduce a polar functional group into a binder resin in order to control electrical characteristics of a toner. However, the present invention involves introducing a polar functional group into each of two resinous materials (A) and (B) which are incompatible with each other and have largely different physical and chemical properties, whereby materials (A) and (B) interact with each other. In other words, it is not possible to achieve the objects of this invention merely by introducing a polar functional group into one resin. The effects and merits of the present invention are briefly explained below. As described above, many conflicting properties are required by a pressure-fixable toner. The toner must be constructed so that it exhibits these properties independently in each step of the imageforming processes. In order to attain this purpose, it is preferred that resin materials having different properties are made to adopt a proper multiphase structure. When mixing two or more kinds of resinous materials having different properties, if they have high compatibility with each other, the mixture obtained cannot exhibit the individual different properties of each resinous material. On the other hand, if they are incompatible with each other, the mixture will meet certain of the various required parameters. However, it is difficult to maintain the dispersed multi-phase structure in a stationary state. Furthermore, the heterogeneous interface between them frequently reduces the properties of the toner. It has been discovered that these difficulties can be overcome by introducing a functional group interaction between two resinous materials (A) and (B) which are incompatible with each other and have different properties. Since binding resinous materials (A) and (B) are properly incompatible with each other, when the materials are mixed, materials (A) and (B) maintain their individual domain, whereby a desired multi-phase structure can be attained. Furthermore, since there is an interaction between the polar function groups of material (A) and those of material (B), the heterogenous interface between materials (A) and (B) is fixed and the multi-layer dispersion structure itself becomes stable. The interaction in this case may be a secondary bonding type of interaction such as hydrogen bonding, electrostatic bonding or alternatively may be a covalent bonding type of interaction such as grafting or crosslinking. It has also been found that when secondary bonding takes place, the stabilization in multi-phase dispersion structure not only facilitates the control of electric characteristics and mechanical properties, but also strengthens the shearing stress and shearing time reliance of the mechanical properties of the toner, which are advantageous because the resulting fixed toner image is free of smudges or smears even when rubbed. When magnetic powder and other fillers having polar surfaces are contained in the toner, interaction between the polar functional groups of resinous materials (A) and (B) and these fillers can be expected Due to this interaction the multi-phase dispersion structure of the toner is more stabilized. Furthermore, mechanical and thermal properties can be improved. It is possible to control the electrical characteristics of the toner in a conventional manner by adjusting the electron donative or electron acceptive property of the polar functional groups of materials (A) and (B). Preferably material (A), which is a soft component having a glass transition temperature below OOC, is present in an amount within the range of 5-50% by weight, preferably 10-30% by weight of the total weight of the resinous materials. If it is contained in an amount below 5% by weight, the toner is poor with respect to pressure-deformability during pressure-fixing. If the content is higher than 50% by weight, the antiblocking property, powder fluidity and producibility of the toner are greatly reduced. On the other hand, it is preferred that material (B), which is the hard component, having a glass transition temperature above 400C, be contained in the range of 5-95% by weight, preferably 10-80% by weight, more preferably 35-65% by weight, based on the total weight of the resinous materials. When the toner further contains a resinous material additional to materials (A) and (B), it is preferred to employ resinous material having good compatibility with material (A), if the additional material is a soft component having a glass transition temperature below OOC, or with material (B) if the additional material is a hard component having a glass transition temperature above 400C. In either case, it is necessary to prepare a toner in such a manner that the proportion of the total soft components containing material (A) be 5-50% by weight of the resinous materials, and the proportion of the total hard components containing material (B) be 50-95% by weight. The toner may contain various kinds of additives such as coloring agents. Examples of useful coloring agents used in this invention include carbon black, magenta, yellow, cyan series pigments as well as Nigrosine, Fast Blue and other dyes. When the toner of this invention is used, for example, in one-component development method, etc., as a pressure-fixing magnetic toner, various kinds of magnetic powder can be included in the toner. The amount of magnetic powder in the toner depends upon various factors such as the conditions of the development process, but generally in the range of 20-80% by weight based on the total weight of the toner. The magnetic toner is preferably adjusted to have an electric resistance of 1012 to 1016 ohm. cm in view of its transferring and developing properties. When the electric resistance is too low, a so-called "blur" phenomenon arises in which a toner image is scattered during the transferring step. When it is too high, background "fog" is increased, or image density is decreased, during the developing step. For the purpose, the magnetic powder is preferably added in an amount of 30-60% by weight based on the total weight of the toner. Examples of useful magnetic powder include metals such as iron, cobalt, nickel, and alloys and oxides of these metals. With respect to magnetic toners, Fe304, -Fe203, cobalt-doped iron oxide, ferrite powders such as powders of MnZn ferrite, etc., are preferably used. Such magnetic powders may be granular form or acicular form depending on the application of the toner, and the size of the powders is generally from 0.01 to 2u. Furthermore, these magnetic powders may be treated on their surfaces with a surface active agent or a fatty acid-, silane- or titanate-series coupling agent before being used. If necessary, the toners may further contain materials such as plasticizers, granular or fibrous organic or inorganic reinforcing fillers, extenders, antioxidants, foaming agents, ionic or nonionic surface active agents. In order to further improve the fluidity, developing and transferring property, and preservative stability of the toner particles or powders, or to prevent filming of the toners on the surface of a photoconductor or improve the cleaning property of the toners, an external additive may be used in combination with the toners. Examples of useful external additives include long chain fatty acids (e.g. stearic acid) and amides or metal salts thereof, fine powders of molybdenum disulfide, carbon black, graphite, fluorinated graphite, silicon carbide, boron nitride, silica, aluminum oxide, titanium dioxide, zinc oxide, fine powders of fluorine resins, polycyclic aromatic compounds, wax-like materials, and fine powders of crosslinked or non-crosslinked resins. These additives are usually solid fine particles having a low surface energy, below 30 N/mm in critical surface tension or having a smooth surface which is below 0.1 in friction coefficient. The additives may also be comprised of fine particles having non-tackiness and some abrasive property. However the additives are not restricted to any such materials. In addition, if necessary, these external additives may be fixed on the surface of toner powders by a hot blast method or otherwise. The developer composition of this invention can be produced by any conventional methods for example, a method comprising fusing whole components, kneading and grinding, a method comprising mixing the binding resinous materials in the form of solution followed by fusing whole components, kneading and grinding, or a spray drying method. When producing a developer composition by a kneading-grinding method, the molecular weight of the hard components including material (B) is preferably controlled so as to make the composition of the particle surface of the developer composition uniform. By controlling the number average molecular weight to about 1000-30 000, the ground interfaces can selectively become a hard component phase containing component (B). The particle sizes of the toner are generally 1-50p, preferably 5 30you. The particle sizes may be controlled by classification if necessary. There is no particular restriction regarding the form of the developer composition of this invention. When the developer composition is used as a toner for a two-component developer, after controlling the static property of the toner with a static controlling agent, the toner is used as a mixture thereof with a carrier material such as an iron powder. The developer composition of this invention can also be used as magnetic toner for a one-component developer by mixing the developer composition with a magnetic powder as described above. When it is used as a magnetic toner, it is possible to develop not only electrostatic latent images but also magnetic latent images. Furthermore, the developer composition of this invention shows excellent fixibility with only the application of pressure. However, as a matter of course, the composition of this invention can be securely fixed by heat and pressure or by heating or by the use of a solvent. Specific examples of this invention and comparative examples are shown below. However, the invention is not limited to these examples. EXAMPLE 1 A mixture of 70 parts of a polystyrene resin (Picolastic D-125, made by Esso Chemical Co., Mw=52,000; Mn=3,000; and Tg=550C), 30 parts of an ethylene-vinyl acetate copolymer (Evaflex 220, made by Mitsui Polychemical Co. Ltd.; MI=150g/10 min; Tge -300C; and content of vinyl acetate 28 wt%), and 10 parts of carbon black (BP-1300, made by Cabot Corporation) were fused and kneaded for 10 min. in a rotor-type kneader. After cooling, the mixture was first roughly ground by means of a crusher and then finely gound by a jet crusher. The fine powders below 5 um and rough particles over 40 um were removed by means of a classifier to provide a toner having a mean particle size of 14 um. The toner was mixed with 0.8% by weight fine powder of hydrophobic colloidal silica. After further mixing a carrier iron powder having particle size of about 80 um was added. The carrier/toner weight ratio was then adjusted to about 100/5. An image test was then performed using a Xerox (registered trademark) 2300 copying machine. In addition, fixing was performed using a pressure fixing apparatus composed of three metallic rolls at a line pressure of 2.5 kg/mm. The initial image quality was relatively good, but when 5,000 copies were made by repeating the operation, the image density was reduced and background fog increased greatly. Fixing was good in appearance but when the images were rubbed, the images came off partially, and fingers and clothes were readily stained. When the properties of the developer were evaluated in order to investigate the cause, it was found that the distribution of charge was broad and the toner stuck onto the carrier surface to deteriorate the image quality. When the toner was further classified into a toner below 10u, a toner of 10-20um, and a toner over 20u, and the rheology characteristics of each sample were evaluated, it was found that the electrical characteristics differed between the fine powder and the rough particle samples. The rheology characteristics were not influenced by any differences in particle sizes. The toner was also found to be inferior in powder fluidity and antiblocking property at high temperature. EXAMPLE 2 Using a mixture of 28 parts of a polystyrene resin (ST-120, made by Sanyo Chemical Industries, Ltd.; Mw=12,000; Mn=5,500 and Tg=700C), 12 parts of a low molecular weight polyethylenic wax having -COOH (2203 A, made by Mitsui Petrochemical Industries, Ltd.; acid value =40, lvivkviscosity average molecular weight)=2,700; o=O.93g/cm3; and rnF=1080C), and 60 parts of a magnetic powder (EPT-1000, made by Toda Kogyo K. K. ), a toner having a mean particle size of 16 um was prepared in the manner as in Example 1. The toner was mixed with 0.5% by weight carbon black and a copy test was performed using a one-component-type copying machine. In the early stage, good development and good tl ansferring property were shown under ordinary circumstances, but when 2000 copies were continuously made, a roughness of image was observed. The cause is considered to be that since filming of the toner onto bee photoconductive material occurred and the development and transfer were carried out selectively, the particle sizes of the toner changed with time. In this connection, when the properties of the rough particle portion of the toner were compared with those of the fine powder portion, they differed from each other and it is considered that the distribution of the composition and multi-phase dispersion structure of the toner were broad arid the toner was unstable. Further, the pressure fixing of the toner at a line pressure of 2.5kg/mm showed the same defects as in Example 1. EXAMPLE 3 The same procedure as in Example 2 was repeated using unmodified polyethylene was (171-P, made by Sanyo Chemical Industries, Ltd.; #v=1,500; op=0.93g/cm3; and mp=105 C) in place of the wax having a carboxy group used in Example 2. No remarkable difference in image characteristics and fixing property was observed as compared with Example 2. EXAMPLE 4 The same procedure as in Examples 2 and 3 was repeated using a polyester resin having -OH at the terminal (GV-700, made by Toyobo Co. Ltd.; Mn=3,000; and Tg=670C) in place of the polystyrene resin used in Example 3. The image characteristics and fixing property were not improved as compared with Examples 2 and 3. EXAMPLE 5 A toner having a mean particle size of 14 um was prepared by the same manner as in Example 1 using the following components; Polystyrene resin (Picolatex D-125, made by Esso Chemical Co.) 30 parts Styrene-allyl alcohol copolymer (RJ-100, made by Monsanto Company; Mn=1,150; and Tg=500C) 40 parts Ethylenic modified resin having OH and -COOH (Dulamin C-2280, made by Takeda Chemical Industries, Ltd.; MI=93g/10 min; and mp=930C) 30 parts Carbon black (BP-1300, made by Cabot Corporation) 10 parts A developer was prepared by mixing the toner with 0.8% by weight fine powder of hydrophobic colloidal silica and further mixing with an iron carrier powder having a particle size of about 80 um in such manner that the carrier/toner weight ratio became about 100/5 and a copy test was performed as in Example 1. When 20,000 copies were made by repeating the operation, images were good. Furthermore, no change with the passage of time was observed. The pressure-fixing property was evaluated at a line pressure of 2.0 kg/m, 2.5 kg/mm and 3.0 kg/mm - and each case showed good fixing property. It is believed that a stable and proper multi-phase dispersion structure was formed by the interaction of the functional group of the styrenic copolymer and that of the modified ethylene resin. Also, it is considered that since the surface composition of the toner particle was mainly composed of the styrenic resin and was uniform, the charge distribution was narrow. This was also confirmed by the analytical result by ESCA, etc. EXAMPLE 6 A magnetic toner having a mean particle size of 15 um was prepared in the same manner as in Example 2 using the following components; Polystyrene resin (ST-120, made by Sanyo Chemical Industries Ltd.) 12 parts Styrene-allyl alcohol copolymer (RJ-100, made by Monsanto Corporation) 12 parts Organic acid graft ethylene wax (2203 A, made by Mitsui Petrochemical Industries, Ltd.) 12 parts Styrene block copolymer (G-1652, made by Shell Chemical Co.; ratio of styrene to ethyl butylate = 29/71; o=0.91g/cm3) 4 parts Magnetic powder (EPT-1000, made by Toda Koygo K.K.) 60 parts The toner was mixed with 0.5% by weight carbon black and when a copy test was performed using a one-component copying machine, all good development and transferring property were shown under all circumstances. Also, when 10,000 copies were continuously made, no change in image quality was observed. When a pressure fixing was applied at a line pressure of 2.5kg/mm, the image was strongly fixed. When the fixed image was subjected to a friction test using an adhesive tape or rubbed by a finger, the image did not come off or stain clothes. EXAMPLE 7 A toner having a mean particle size of 17 um was prepared in the manner as in the other examples from the following composition; Polyester resin (GV-700, having -OH, made by Toyobo Co. Ltd., Mn=3,000; and Tg=670C) 20 parts Oxidized polyethelyne wax (E-300, made by Santo Chemical Industries, Ltd., acid value 22,; Mv=2,000; and mp=1040C) 7 parts Ethylene-vinyl acetate copolymer (UE-722, made by Toyo Soda Manufacturing Co. Ltd.; MI=400g/ 10 min; Tge -30 C; and content of vinyl acetate 28 wt%) 3 parts Magnetic powder (RB-BL, made by Titan Kogyo K.K.) 70 parts The toner was mixed with 0.4% by weight carbon black and 0.2% by weight silica powder. When a copy test was performed as in Example 6, a good pressure fixing level and good image quality was obtained. EXAMPLE 8 A magnetic toner having a mean particle size of 13 um was prepared by fusing and kneading a mixture of 45 parts of a styrenic copolymer produced by copolymerizing styrene, methyl methacrylate, butyl methacrylate and methacrylic acid and having an acid value of 30, Tg of 65 0C, Mw of 36,000 and Mn of 8,000; 25 parts of a modified ethylenic resin having a hydroxy group (Dumilan D-219, made by Takeda Chemical Industries, Ltd.; My=1709/10 min.; and mp=930C); 5 parts of carbon black (Raven 3500, Colombian Carbon Co.) and 30 parts of magnetic powder (EPT-1000, made by Toda Kogyo K.K.), following by grinding and classifying. The toner was mixed with 0.2% by weight zinc stearate and 0.6% by weight fine powder of hydrophobic silica, and a copy test was performed using a one-component copying machine. When 10,000 copies were made by repeating the operation, the development, transferring property and image quality were good and the pressure fixing at a line pressure of 3.0 kg/mm was very excellent. The results obtained in Examples 1-8 are summarized in Table 2. D e v e l o p e r @@@@ @ @ @ @ @ @ @ @@@@@ @@ckgrc@@@d @@s@@@@ *1 Dens@@y Denstty @@o@ (@@) @oaer @@@@@@ Toner (Parts) Initi@@ Ialtial Initisi fer Rate @@ -------- -------- -------- Fi@ger Binding Resinous Material Coloring Magaetic at 5,000 at 5,000 at 5,000 Smudge at 20 C, @oi Example Material (A) Material (B) Other Resin Agent Powder Carrier Copies Copies Copies *2 at 30 C, 85% 5 Etylene modified Styrene-allyl Polystyrene Carbon 1,3 0.01 6 #P. 86% resin having -OH alcohol copolymer black - Iron ------------------------ 3 --and -COO@ 1.2 0.01 6 82 (30) (40) (30) (10) 6 Organic acid Styrene-allyl Polystyrene Magnetite graft ethylene alcohol copolymer (12) - - ------------------------ 2 --wax Styrenic block 1.4 0.02 6 75 copolymer (12) (12) ( 4) (60) 7 Oxidized poly- Polyester having Magnet 1.2 0.02 6 85 ethylene wax -O@ - - ------------------------ 4 -- ( 7) 1.2 0.02 5 70 Ethylene-vinyl acetate copolymer ( 3) (20) (70) Etylene modified Styrenic copoly- Carbon Magnetite 1.4 0.01 6 89 8 resin having -OH mer having -COOH black - ------------------------ 3 -- (25) (45) ( 5) (30) 1.3 0.02 6 82 Etylene-vinyl Polystyrene Carbon 1.3 0.10 55 80 acetate copoly- - black - Iron ------------------------ 5 --mer 0.9 0.20 3 75 1 (30) (70) (10) 2 Polyethylene Polystyrene Mognete 1.2 0.02 5 78 Wax having - - - ------------------------ 5 -- -COOH 1.0 0.08 4 54 (12) (28) (60) 3 Polyethylene Magnete 1.2 0.02 5 - - wax - - ------------------------ 5 (12) 0.9 0.08 4 Polystyrene (28) (60) 4 Polyester having Polyethylene Magnetite 1.4 0.03 6 75 -OH wax - - ------------------------ 5 -- (28) (12) (60) 1.0 0.10 4 55 Note: *1 Image density was measured when an original having an optical density of 0.7 was copied. *2 Finger smudge shows the degree of smudge of an image or finger upon rubbing the image with finger after pressure fixing. Grade 5 shows that smudges occur in handling of the copied sheet and the fixed image is transferred to a back surface of sheet which is in contact with the image when the copy sheets are stacked. *3 Toner transfer rate is the rate of toner transfer to a sheet on which a toner image is fixed. Higher value shows a better toner property. It is clearly seen from Table 2 that the toner of the present invention provides an excellent toner image, free of background fogs, with high resolution even after 5,000 reproductions and is thoroughly fixed by the application of pressure so that, in contrast to a conventional toner for pressure fixing, the fixed toner image does not smudge or adhere to a finger when rubbed. Further the fixed toner image does not transfer to a back surface of a sheet in contact with the image during storage. Furthermore, the toner transfer rate of the toner of the present invention is not so decreased even at an increased humidity. In particular, the magnetic toner of the present invention has a markedly stable toner transfer rate as compared to a conventional magnetic toner.

Claims: claitT)s: 1. A developer composition comprising an intimate mixture of a resinous material (A) having a polar functional group and a glass transition temperature below O C; and a resinous material (B) having a glass transition temperature above 40 C and a polar functional group capable of interacting with the polar functional group of the material (A), wherein the resinous material (B) is incompatible with the material (A). 2. A developer composition as claimed in claim 1, further comprising a fine magnetic powder present in an amount of from 20 to 80% by weight based on the total weight of the developer composition. 3. A developer composition as claimed in claim 1 or 2, wherein the material (A) is an olefinic polymer having a hydroxy group, carboxyl group or carbonyl group as the polar functional group, and wherein the material (B) is a styrenic polymer having a hydroxy group, carboxyl group, or a dialkylamino group as the polar functional group. 4. A developer composition as claimed in claim 1 or 2, wherein the material (A) is an olefinic polymer having a hydroxy group, carboxyl group or carbonyl group as the polar functional group, and the material (8) is a polyester resin having a hydroxy group, carboxyl group or dialkylamino group as the polar functional group. 5. A developer composition as claimed in claim 3 or 4, wherein the olefinic polymer is oxidized polyethylene, ethylene-acrylic acid copolymer or organic acid graft polyethylene. 6. A developer composition as claimed in claim 1 or 2, wherein the combination of the materials (A) and (B) is of oxidized polyethylene and styrene-allyl alcohol copolymer; organic acid graft polyethylene and styrene-allyl alcohol copolymer; ethylene-acrylic acid copolymer and styree-allyl alcohol copolymer; ethylene-vinyl acetate copolymer and sty^;;ne-(meth) acrylic acid copolymer; oxidized polyethlene and styrene Cimethylaminoethyl methacrylate copolymer; organic acid graft polyethylene and styrene-dimethylamino-ethyl methacrylate copolymer, or organic acid graft polyethylene and hydroxy group-containing aromatic polyester. 7. A developer composition as claimed in any preceding claim wherein the material (B) is from 35 to 65% by weight of the total weight of resinous materials. 8. A developer composition as claimed in claim 2 or claim 2 and any claim dependent therefrom wherein the magnetic powder is from 30 to 60% by weight of the total weight of the developer composition, and wherein the developer composition has an electric resistance of from 1012 to 1016 ohm. cm. 9 An electrophotographic process comprising developing an electrostatic latent image with a developer composition as claimed in any preceding claim and fixing the thus-developed image by the application of pressure.

Inventors: HASHIMOTO, KEN C/O FUJI XEROX CO. LTD., MATSUI, IZURI C/O FUJI XEROX CO. LTD., TAKASHIMA, KOICHI C/O FUJI XEROX CO. LTD.
Applicants: RANK XEROX LIMITED
Application year: 1982
Main classification: G03G9
IPC codes: G03G9