JPS6342252B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a heated roller fixing type electrophotographic developer. Electrographic imaging and development methods, such as electrophotographic imaging methods and techniques, are described in, for example, U.S. Pat.
No.; 2551582; 2825814; 2833648; 3220324
No. 3220831; No. 3220833 and other patents and other literature. Generally, these methods have in common the step of forming a latent electrostatic image on a normally insulating electrophotographic element. This latent electrostatic charge image is converted to a visible image by processing with an electrostatic developing composition or developer. Conventional developers include triboelectric magnetic materials such as iron filings, iron powder, or iron oxide, or triboelectric non-magnetic materials such as glass beads or crystals of inorganic salts such as sodium chloride or potassium chloride. Contains carrier. In addition to this carrier, electrostatic developers contain toner which is electrostatically attracted to the carrier. Toners usually contain dyes or pigments, such as carbon black, if desired.
A particulate polymeric material that may be blackened to make the image visible with colorants such as. To develop an electrostatic image, a dry developer is applied to a charged surface by a variety of methods to form an image. One such technique is cascade development, which is described in US Pat. No. 2,618,552. Another method is known as magnetic brush development and is described in US Pat. No. 3,003,462. In conventional electrophotography, a developed image is formed on a photoconductive element and then transferred to an image receiving sheet. The image transferred in this manner is fixed by heating and melting. That is, it becomes a permanent image.
Therefore, the toner material must be soluble under temperature conditions that will not cause scorching or other physical damage to the receiver sheet, which is generally made of paper. Various methods and devices have been developed in the electronic recording industry for fixing transferred images. A typical method is to simultaneously apply heat and pressure, for example, to bring an image receiving sheet carrying a transferred developed toner image into contact with a heated fusing roller. In addition to using heated fusing rollers, other methods may be used to fuse the developed toner image, such as contacting the developed toner image with a heated platen or similarly heated device. I can do it. In any case, no matter what type of heat fusing equipment is utilized, during the fusing operation each toner particle of the developed image is "off-setting".
It turns out that there is a real problem of causing (off-setting). Off-setting is the undesirable transfer of toner particles from a developed toner image carried on a receiver element (eg, a copy sheet) to the surface of a heat fusing device. Therefore, as the surface of the fuser becomes contaminated with toner particles, further use of the fuser thus contaminated will result in the toner particles adhering to the surface of the fuser being transferred to the next copy sheet or It was found that the image was transferred to the image receiving element. As a result, a ghost image of an already fused image is formed on the next copy sheet, or toner material is deposited on the spine of the next copy sheet, i.e., scumming or discoloration occurs on the spine of the next copy sheet. A phenomenon occurs. In accordance with the present invention, an improved method for making a developer comprising fine powder carrier particles and crosslinked fine powder toner particles has been developed. The crosslinked micropowder toner particles used in the present invention consist of a soluble binder polymer, which is formed by crosslinking a previously polymerized non-crosslinked polymer with a crosslinkable compound. This is the crosslinked polymer thus obtained. The molecular chains of this binder polymer are then non-crosslinked, consisting of a binder polymer that is identical to the crosslinked toner particles of the present invention, except that the molecular chains, such as those of conventional toner binder polymers, are not crosslinked. Compared to toner particles,
Sufficient post-polymerization crosslinking extends the effective fusing range of the crosslinked toner particles by at least about 10°C. The binding energy or strength of each crosslink in the crosslinked binder polymer used in the present invention must be greater than or equal to about 8 kcal/mole. The reason for this is that polymers that contain only "weak crosslinks" with a bond energy of about 8 kcal/mole or less, such as polymers in which the bonds between each polymer chain are hydrogen bonds, are not sufficiently bonded to each other. This is because the range of polymer fusion is not substantially expanded. In a particularly preferred embodiment of the present invention, the micropowder toner particles used in the present invention include a colorant and a crosslinked fusible binder polymer derived from styrene. These preferred binder polymers provide an effective fusing range of at least 100° C. and have a higher temperature than non-crosslinked toner particles consisting of exactly the same polymers as described above, except that they are not in the crosslinked form after said polymerization. It is sufficiently crosslinked after polymerization to extend the effective fusing range of the crosslinked toner particles of the present invention by at least about 10°C. By cross-linking the molecular chains of the binder polymer material used in the dry electrographic toner composition after polymerization, the temperature range in which the toner particles melt and thereby fuse to the image receiving element is surprisingly improved. In other words, it was found that the effective fusion range could be expanded. By widening the effective fusing range of the electrographic developer composition, the range of temperature variation in the surface temperature of the fusing device used to fuse the developer composition is widened. As a result, the temperature range is expanded and toner off-setting occurs to a lesser extent or to a negligible extent, thereby eliminating the need for conventional toner particles containing non-crosslinked or only surface-crosslinked polymeric toner particles. Toner offset that occurred when using the developer composition is eliminated or substantially reduced. To our knowledge, dry development techniques for electronic recording have avoided the use of crosslinked polymeric toner particles except in very specific cases. For example, Wright, July 11, 1972;
Olson, US Pat. No. 3,676,350, describes that the surface of certain polymeric toner particles that are treated with a glow discharge can be cross-linked to improve the anti-caking properties of these toner particles. Toner particles that are crosslinked only on the surface, as shown in the Examples, do not improve the effective fusing range characteristics of the present invention. Also, thermosetting polymer particles of diallyl phthalate or diallyl isophthalate polymers are used to form the latent image into a toner image, and the polymer in the toner image is crosslinked to improve the storage properties of the toner image. That was recognized. For example, French Patent No. 2083064 dated December 10, 1971
No. 2, No. 1, No. 1, No. 1, No. 1, No. 1, 2003, 2003, discloses a method in which non-crosslinked thermosetting polymer toner particles of a polymer of diallyl phthalate or diallyl isophthalate are fused onto an image-receiving sheet and cross-linked on the image-receiving sheet to form a permanent image. ing. The resin particles are blended to avoid crosslinking during the toner preparation process or during the development process prior to fusing and crosslinking of the toner image. See GB 1174571, page 3, lines 90-97. There are several reasons why crosslinked toner materials have generally been considered unsuitable for conventional electrostatic development and fusing operations. The first reason was that it was believed that crosslinking the toner would increase its melting point and require substantially higher fusing temperatures. Of course, this is not desirable. This is particularly undesirable if the receiving element to which the toner is fused has a low carbonization point, such as when plain paper is used. Another widely accepted view of the above is
One major reason was that it was expected that crosslinking polymeric toner particles would provide a material that could not be easily melted. It would have been thought that crosslinking a toner polymer would weaken its thermoplastic properties and result in polymer particles that behaved more like thermoset polymer particles. In such cases, the crosslinked polymer would be considered to be substantially infusible due to its thermosetting properties. That is, it was thought that it would not melt easily and therefore would not be sufficiently fixed to the support. Another reason for this view is that cross-linked toner particles, even if they can somehow be brought into a molten state, are less effective at reaching the receiver element than non-cross-linked or merely surface-cross-linked particles. This is probably because it was thought that a lot of heating time would be required for fusion. Such long fusing times lengthen the fusing operation, making such toner materials unsuitable for use in high speed copying systems. As used herein, the term "effective fusing range" is defined by the following roller fuser test; the fusing properties of each sample toner are determined in a conventional test contact roller fuser. The test contact roller fusing device consisted of a cylindrical steel compression roll coated with a copolymer of tetrafluoroethylene and fluorinated ethylene propylene (e.g., sold under the trademark TEFLON FEP of DuPont). Consists of elastic fusing rolls. The double rolls are mounted so that their central axes are parallel to each other and their roll surfaces are in contact. The fuser roll has an outer surface layer wrapped with a layer of approximately 0.13 cm thick or less of "ECCOSIL 4952" trademark silicone rubber available from Emerson-Cumming. The surface speed of the compression roll and fuser roll is 5 inches/second. The compression rolls are adjusted to provide a linear pressure of 15 pounds per inch at the nip point formed by the interface of the compression roll and fuser roll. The compression roll has an outside diameter of approximately 5.08 cm and the fusing roll has an outside diameter of approximately 7.94 cm. The fuser roll can be heated in a variety of ways, such as by radiant heating using infrared lamps. The surface temperature of the fuser roll is monitored by a thermocouple in contact with the roll. Before actually testing the toner particles, the fuser roll used for the test should be tested at: (a) the surface temperature of the roll;
100 sheets of paper to which no toner has been fused (hereinafter referred to as "blank paper") are passed between the rolls while maintaining the temperature at 177°C, and then (b) the XEROX 3600-7000 toner is completely fused to form a Macbeth Quantalog.
Paper 50 coated with a solid area with a reflective optical density of 0.9 as measured with a ModelRD-100 reflective densitometer
The sheet was passed through and inspected. The paper used to inspect the fuser roll and perform the fusing tests described below may be, for example, “International Xerographic White
A white 20 weight bond paper available as ``Substance 20''. When applying toner to this paper, apply it to the correct watermarked side. Each sample of toner to be tested has a 2-40 Grind by fluid energy mill until micron. Then
A solid area shape with a width of approximately 1.90 mm made by fusing samples of various toners onto a standard piece of paper measuring 21.6 cm x 27.9 cm.
cm, a rectangular test strip approximately 10 cm long was formed on a piece of paper by conventional electrostatic methods. This test strip is provided in the center of the paper so that the long length of the test strip and the long length of the paper are parallel. The reflection optical density of this solid area test zone was measured with the above densitometer and was found to be 0.9. The strip of paper with such a test strip is then passed through a contact roller type fuser as described above. Immediately following the paper to which the toner has been fused, a blank paper in the same manner is placed in the roller fusing device to check whether there is a toner offset phenomenon from the paper to which the toner is fused to the fusing roll. send to. To determine whether the ghost image of the first toner test band has transferred from the fuser roll to the blank paper, simply look at each blank paper with the naked eye. good. When significant toner offset occurs, it can be easily determined by such visual observation.
Offset occurs when enough toner adheres to a blank paper to give it an optical density that is 0.02 or more greater than the reflected optical density that the blank paper alone had before it passed through the fusing device. It is defined as "ivy". To determine the effective fusing range of various toner compositions, a series of paper samples fused with the same toner for each toner composition to be tested is prepared as described above. Each toner-fused paper sample is then fed into a standard contact roller fusing apparatus in the same manner as above, following the blank paper. The surface temperature of the fuser roll is then raised from room temperature to create a temperature diagram for each toner sample for each paper to which the toner of the series of toner samples has been fused. As a result, two surface roller fusing temperatures, the "minimum sufficient fusing temperature" (MAF) and the "hot offset" (HO) temperatures, were accurately determined for each toner composition tested. It is determined. The MAF temperature for each toner composition tested is
It is defined as the lowest fuser roll temperature above room temperature at which offset phenomena do not occur and the toner image is sufficiently fused to the sheet of paper. Whether or not it has been sufficiently fixed to the sheet paper is determined by an adhesive tape test as described later. The HO temperature for each toner composition tested is the lowest fuser roll temperature above the MAF temperature at which toner offset is again observed as described above. As mentioned above, whether or not the adhesive has been sufficiently fixed can be quantitatively determined by the adhesive tape test.
To perform the adhesive tape test, use a 1.27 cm wide adhesive tape with suitable adhesive properties, such as “Bear
Select a tape such as "Brand. No. 303 Cellophane Tape." Place the tape of your choice of adhesive strength on a flat, polished stainless steel plate. Only the dead weight of the roller is used to attach each tape "sticky" tape by passing the brass roll four times at 5.08 cm/S. to attach the tape to the steel plate. Remove the oil, wash with an aqueous detergent solution, rinse with distilled water, and dry. Then, immediately use an Instron tester at a relative humidity (RH) of 50%, a temperature of 25°C, and an angle of 180°. The tape is peeled off at a speed of 30.48 cm/min. The range of peel force recorded is the tape peel value of grams/1.27 cm. Peaks or valleys are not included in the peel value, nor are the first and last 1.27 cm of peeled tape. Tapes that may be used have a peel value of 300 to 475 gr./1.27 when tested in this manner.
cm. At least one day before testing each toner image to be evaluated for sufficient fixation.
Equilibrate at 25℃ and 50%RH. A 1.27 cm wide adhesive tape of suitable tack is applied over the fixed toner image using the dead weight of the previously described brass roller and passed over it four times at 5.08 cm/sec. Immediately peel off this tape at an angle of 180° and at a speed of 15.24 cm/min. If fibers from the receiving paper adhere to the tape during peeling, the test is invalid. The optical reflection density is measured at several locations where the tape is removed and the average value is calculated. Fixability is defined as follows. Fixability = Image density after peeling off the tape / Image density before applying the tape The minimum temperature for sufficient fixation is fixability of 0.50.
It is defined as the lowest fusing roll temperature that is equal to or higher than that. Therefore, for a given toner composition, the effective fusing range is expressed as the difference between the HO temperature and the MAF temperature. Offsets in the sense defined above do not occur within this effective welding range. As previously noted, the crosslinked molecular chains of the polymeric binder included in the crosslinked toner compositions of the present invention extend the effective fusing range by at least 10°C, resulting in improved toner resistance to offset. ing. (This improved resistance to offset is specifically referred to as improving the offset latitude of the toner.) These toner compositions found to be particularly useful by the present invention have The bonding range is extended from just above 20°C to 40°C or more, and therefore has an effective welding range of 100°C to 125°C or more than 125°C. The crosslinked toner composition used in the present invention exhibits a 10° C. extension in the effective fusing range, measured relative to a comparative non-crosslinked toner. In order to provide a sufficiently meaningful basis of comparison, a crosslinked toner consisting of a crosslinked polymer obtained by crosslinking a previously polymerized noncrosslinked polymer with a crosslinking compound and a control noncrosslinked toner. The toners should contain the same amount of polymer binder, and the MAF temperature of the crosslinked toner and that of the non-crosslinked toner should be of the same order of magnitude. Accordingly, the term "comparative non-crosslinked toner" refers to (a) a non-crosslinked toner containing the same binder polymer as used in the crosslinked toner except that the binder in the non-crosslinked toner is in non-crosslinked form; and (b) its MAF temperature is that of the cross-linked toner.
It is defined as a toner that is within ±15°C of the MAF temperature. The term "crosslink" is defined in this invention to include both covalent and ionic crosslinks. Both types of crosslinks have binding energies of about 8 kcal/mole or higher. Covalent crosslinking is preferred for a variety of reasons, particularly because covalently crosslinked polymers are easier to produce than ionic polymers.
The binding strength of covalent cross-linking is generally about 40kcal/
larger than mole, and the bonding strength of ionic crosslinking is approximately
Greater than 10kcal/mole. As mentioned earlier,
Polymers in which the crosslinks of the unit chains of each polymer are connected by hydrogen bonds are not useful in the present invention. In general, the binding strength of hydrogen bonds is approximately 2 to 7 kcal/
It's a mole. The use of both covalent and ionic crosslinks will be discussed in more detail. Preferred binder materials for use in the present invention are obtained from styrene, styrene analogs and monomer mixtures comprising the styrenic materials. Such binder materials generally consist of at least about 40 wt% to 100 wt% styrene or styrene congeners. The expression "styrene or styrene analog" used in the present invention is used interchangeably with the expression "styrenic material." In the present invention, the styrene material has the general formula: (However, in this formula, R is hydrogen; halogen such as chlorine or bromine; lower alkyl such as methyl, ethyl, propyl, isopropyl, butyl containing 1 to 4 carbon atoms in the alkyl moiety, and halides thereof, It is defined to include monomers or mixtures of monomers having lower alkyls, including halogenated alkyls, and their halogenated derivatives. Binder materials found to be particularly useful in the present invention range from about 40 to about 90
Weight percent styrenic material, preferably styrene itself, and from about 10 to about 60 weight percent vinyl monomers other than styrene [e.g., branched alkyl and cyclo, where the alkyl group has up to 20 or more carbon atoms An example of cycloalkyl is cyclohexyl methacrylate], including alkyl acrylates and methacrylates, such as cyclohexyl methacrylate. As mentioned above, typical binder materials found to be particularly useful include 40 to 90 wt% styrene and 1 to about 4 carbon atoms in the alkyl moiety, such as methyl, ethyl, isopropyl, butyl, etc. Lower alkyl acrylate or methacrylate about 5~
about 50 wt% and about 5 to about 50% higher alkyl acrylate or methacrylate [e.g., ethylhexyl acrylate or methacrylate] in which the alkyl group has about 6 to 20 or more carbon atoms;
This is a polymer obtained from 50wt%. Many other useful styrenic materials containing toner particles are described in the following US patents: 1959-12
Patent No. 2917460, March 15th; Reissue No. 25136, March 13th, 1962; Patent No. 2788288, April 9th, 1975;
April 12, 1953 Patent No. 2638416; November 18, 1952
Japanese Patent No. 2618552 and November 17, 1953 Patent No.
No. 2659670. In a preferred embodiment of the invention, the covalently crosslinked polymeric binder used in the toner particles of the invention can be easily produced by curing a polymer that has crosslinking sites in its molecular structure. . The various chemically active moieties that act as crosslinking sites in the molecular structure of polymers are well known in the polymer industry. Curing of polymers having these crosslinkable sites is generally promoted using a combination of heat and a crosslinkable compound (commonly referred to as a "curing agent"). Various catalysts are also used in accordance with conventional polymerization methods. Table 1 shows some typical crosslinkable sites and corresponding curing agents.

[Table] -glycidyl methacrylate -co-methyl methacrylate)

[Table] -ethylhexyl methacrylate -co-hydroxyethyl methacrylate)
The ionic crosslinking binder used according to the invention is prepared in a manner similar to that described above in the presence of an ionic crosslinking compound such as calcium hydroxide, but with covalent crosslinking. The binder is made by curing a polymerizable binder in the presence of heat and an ionic crosslinking compound to form covalent chemical bonds between adjacent crosslinked portions of the polymer. The difference between ionic cross-linked binders and the above-mentioned covalent cross-linked binders produced by curing is that in the former, the bonds between the cross-linked moieties of adjacent polymer chains are not true covalent chemical bonds, but rather ionic. This seems to be a union of sexes. The ionic bond is formed by heating a polymerizable binder having an ionic crosslinking portion in its molecular structure in the presence of an ionic crosslinking compound. The cross-linked binder used in the present invention has a softening point of about 40°C to about 40°C, regardless of its chemical composition.
Preferably it is a cross-linked binder at 200°C. This is because, in such cases, the formed toner particles are easily fused to a conventional image-receiving sheet to form a permanent image. Particularly useful crosslinking binders are those having softening points in the range of about 40<0>C to about 65<0>C. This is because toners containing such binders can be used in high speed electrographic copying machines that use saline paper as the receiving paper to which the toner image is fused. Of course, if a different type of image receiving element is used, such as a synthetic high melting point polymer sheet, a metal sheet, etc., a crosslinked polymer having a softening point above the specified one will be used. The "softening point" used in this invention is a needle pressure of 48p.sia
and the temperature at which the polymer becomes soft, measured using a DuPont "Mode 1941TMA" (thermodynamic analyzer) at a heating rate of 5° C./min. The toner compositions used in the present invention may be comprised of varying amounts of the crosslinked binder polymers described above depending on many factors, including the type and amount of colorants or other modifiers incorporated into the composition. . Advantageously, the cross-linked meltable binder is present in the toner composition used in the present invention in an amount of 25 weight percent or more. In a preferred embodiment of the present invention for use of the toner compositions of the present invention in relatively high speed office copying equipment, the toner compositions contain at least 50 weight percent, preferably from 75 to 95 weight percent, of a crosslinked binder polymer as described above. I found out that it is better to use . The toner composition produced by the method of the present invention can be produced by various methods such as spray drying and melt mixing. Currently, office copying equipment primarily uses particles having an average diameter of about 1.0 to 30 microns, although particles having an average diameter of about 0.1 micron to about 100 microns can be used. However, larger or smaller particles may be used if special development methods or special development conditions are desired. For example, U.S. Patent No. 12, October 1954,
Powder cloud development, as described in US Pat. No. 2,691,345, can use extremely fine toner particles on the order of about 0.01 microns. The melt-mixing method for producing toner compositions produced by the method of the present invention involves melting a powdered binder polymer and adding it to any other necessary or desired additives, including colorants such as dyes or pigments. It consists of a process of mixing with The polymer is readily melted onto heated mixing rollers that are used to agitate or mix the polymer and additives to promote thorough mixing of the various components. After mixing,
The mixture is cooled and solidified. The solid mass formed is then finely ground into small particles to form a free-flowing powder toner composition of the desired size. Various colorants selected from dyes and/or pigments are used in the toner compositions of the present invention. These colorants color the toner and/or make the toner more visible. Of course, if a developed image with low optical opacity is desired, a toner composition with suitable loading characteristics can be prepared without the use of a colored material. If it is desired to use colorants, the colorants used are as a rule selected from among the compounds described in "Color Index, 2nd Edition, Volumes 1 and 2". An effective coloring agent is “Hansa Yellow.”
Hansa Yellow G (CI11680)” “Nigrosine Spirit Soluble”
Spirit soluble) (CI50415)""Chromogene Black ETCO (C.
I.45170)""Solvent Black 3
Black3) (CI26150)” “Fuchsine N” (CI42510)” “CIBasic Blue9” (C.
Carbon black is a particularly effective colorant.The amount of colorant added can vary over a wide range, e.g., from about 1 to about 20 percent by weight of the crosslinked binder. Particularly good results are obtained when amounts of ~10 percent are used.
In some cases, it is desirable not to use a colorant, in which case the minimum density limit is zero. If desired, other modifiers such as various long chain anionic or cationic surfactants, conductive materials, and magnetic materials may be incorporated into the toner compositions of the present invention. Other toner additives that may be incorporated into toner compositions include
There are materials described in US Pat. No. 3,577,345 to Jacknow et al. Generally, when the various modifiers described above are used in the toner compositions of the present invention, their total amount (excluding the weight of colorant) should be no more than about 30% of the total weight of the toner composition. The toner composition produced by the method of the present invention can be mixed with a carrier vehicle to form a developer composition. The carrier vehicle used with the toner compositions of the present invention to form the novel developer compositions is selected from a variety of materials. Useful carrier vehicles for use in the present invention are various non-magnetic particles such as glass beads, crystals of inorganic salts such as sodium or potassium chloride, hard resin particles, metal particles, and the like.
Additionally, magnetic carrier particles can also be used in the present invention. Suitable examples of magnetic carrier particles are ferromagnetic materials such as iron, cobalt, nickel, and alloys and mixtures thereof. Other useful magnetic carriers include various film-forming resins, e.g.
Date Mirror (Miller) U.S. Patent No. 3547822;
Miller, U.S. Pat. No. 4, January 1972.
3632512; filed March 21, 1972; McCabe U.S. Application No. 236765 "Electrophotographic Carrier Vehicles and Developer Compositions - Case B"; March 1972;
Kasper et al., U.S. Application No. 236,584, "Electrophotographic Carrier Vehicle and Developer Composition Case C," filed March 21, 1972, and Kasper, U.S. Application No. 236,614, "Electrophotographic Carrier," filed March 21, 1972. Vehicle and developer composition - ferromagnetic particles coated with an alkali-meltable carboxylated polymer, such as those described in Case D''. Other useful resin-coated magnetic carrier particles are those coated with various fluorocarbons such as polytetrafluoroethylene, polyvinylidene fluoride, and mixtures thereof, including copolymers of vinylidene fluoride and tetrafluoroethylene. They are carrier particles. A typical developer composition containing the toner and carrier particles described above generally comprises from about 1 to about 15 weight percent of the particular toner particles and from about 85 to about 99 weight percent of the carrier particles. The average particle size of conventional carrier particles used in cascade or magnetic brush development is from about 30 to about 1200 microns, preferably from 60 to 300 microns. The toner and developer compositions described above are used to develop electrostatic image patterns. Such developable electrostatic image patterns can be formed by a number of well known methods, for example carried on a photosensitive photoconductive element or an image receiving element having a non-photosensitive insulating surface. Suitable dry development methods are detailed in U.S. Pat.
2618551; 2618552; 2638416, in which a cascading developer composition is cascaded across an electrostatic image pattern. Another method is to apply toner particles from a magnetic brush developer composition as described in US Pat. No. 3,003,462. Yet another effective development method is powder cloud development, which uses a gaseous medium such as air as a carrier vehicle to transfer toner particles to the electrostatic image pattern to be developed. This development method is more fully described in US Pat. Nos. 2,691,345 and 2,725,304. Still yet another development method is fur brush development, in which the bristles of a brush are used to transfer toner particles to the electrostatic image pattern to be developed. This development method is described in more detail by Walkup, US Pat. No. 3,251,706. As is clear from the foregoing, the improved electrophotographic development method using the toner composition produced by the method of the present invention can be applied to both the inorganic particles conventionally used in cascade development and the magnetic particles conventionally used in magnetic brush development. Various types of carrier vehicles can be used, ranging from gaseous media used in powder cloud development to fur brushes used in fur brush development. After the toner composition produced by the method of the present invention is deposited into an image, the image can be melted and fused onto a substrate carrying the toner image as described above. If you wish,
The unfused image can also be transferred to new copy paper and then fused to form a permanent image thereon. Example: Crosslinking of styrene-acrylic polymers by mixing Polymer number: a b Toner number: -1 -2 Polymer preparation a Contains 50 g of styrene, 25 g of 2-ethylhexyl methacrylate, 25 g of methyl methacrylate and 3 g of azobisisobutyronitrile The suspension was flushed with nitrogen and heated at 60° C. for 24 hours to effect suspension polymerization. Polymerization was completed by heating at 95° C. for 6 hours. The polymer formed is poly(styrene-co-methyl methacrylate-
co-2-ethylhexyl methacrylate). b Polymer produced in the same manner as polymer a, except that 0.5 g of methacrylic acid monomer was added as an initial monomer reactant. The methacrylic acid units of the polymer formed act as crosslinking sites. Toner manufacturing method -1 is a control toner containing 100 parts of a and 5 parts of carbon black (Regal 300R) purchased from Cabot.
2 parts were mixed on two rubber roll mills. This composition was ground to toner size (2-40 microns) in a fluid energy mill. -2 is 100 parts by weight of polymer Ib, 0.3 parts by weight of triethylenediamine as a catalyst, and a diepoxide crosslinking compound (commercially available from Ciel Chemical Co., Ltd. under the trade name Epon ^R 1001).
3 parts by weight, and Regal 300R Carbon Black 5
It is a crosslinked toner produced by mixing parts by weight on a two roll rubber mill. During this mixing operation,
The rheological properties of the melt changed from that of a non-crosslinked polymer to that typical of a crosslinked polymer. The mixture was ground into toner sized particles in a fluid energy mill. Roller fusion results

[Table] The data in Table 2 shows that the crosslinked toner extended the effective melting range by 42°C. Example: Crosslinking of styrene-acrylic polymer Polymer number: a Toner number: -1 -2 Polymer manufacturing method a Styrene 300g, methyl methacrylate 210g,
90 g of 2-ethylhexyl acrylate, 50 g of ethyl acrylate and 18 g of benzoyl peroxide
A mixture consisting of poly(vinyl alcohol)
Add 0.75g to 800ml of water at a temperature of 75°C while stirring.
It was added dropwise over a period of 3 hours. Polymerization was carried out under a nitrogen atmosphere and continued for 12 hours after monomer addition. The product was collected by filtration, washed with water and dried. The polymer produced was poly(styrene-co-methyl methacrylate-co-2-ethylhexyl acrylate-co-ethylacrylacetate). Toner manufacturing method 100 parts by weight of polymer a and 5 parts by weight of Regal 300R carbon black were mixed in a two roll rubber mill. The mixture was milled through a 20 mesh screen and divided into two equal parts. -1 was made by milling one of the two halves of the above material with a non-crosslinked control toner into toner sized particles in a fluid energy mill. -2 is a cross-linked toner manufactured by adding the remaining half of the above material to a 35% formaldehyde aqueous solution adjusted to pH 9 with sodium hydroxide. This mixture was tumbled dry for 48 hours. The solubility of this material was determined with methylene chloride before and after treatment with aqueous formaldehyde. This material was soluble in methylene chloride before formaldehyde treatment, but not after. This indicates that cross-linking has already occurred. This material was milled into toner-sized particles using a fluid energy mill. Roller Fusing Results The toner was tested in a roller fuser as described above and the following results were obtained.

[Table] The data in Table 3 show that cross-linking extended the effective melting range by 42°C. Example: Mixed ionic crosslinking of styrene-acrylic polymer Polymer number; a: Same as a in Example. b Toner number; -1: Same as -1 in Example. -2 Polymer manufacturing method a; poly(styrene co-co-
Methyl methacrylate-co-2-ethylhexyl methacrylate) b: A polymer prepared in the same manner as Polymer a of Example, except that 5.0 g of methacrylic acid was added as one of the initial monomer reactants. The formed polymer is poly(styrene-coated)
methyl methacrylate-co-2-ethylhexyl methacrylate-co-methacrylic acid). Toner Preparation Method-1 is a non-crosslinked control toner as described in the Examples. -2 is a crosslinked toner prepared by mixing 100 parts of b, 2 parts of calcium hydroxide as an ionic crosslinking compound, and 5 parts of Regal 300R carbon black in a two roll rubber mill. After mixing, the mixture was heated at 175°C for 90 minutes. The mixture was then ground into toner size (2-40 micron) particles in a fluid energy mill. Results of Roller Fusing The operation of fusing toner to paper was carried out using the roller fusing device described above, and the following results were obtained.

[Table] The data in Table 4 shows that the effective melting range can be extended by 28°C by ionic crosslinking. Example: A magnetic brush developer composition was prepared by mixing about 3 to 4 weight percent each of crosslinked toners -2, -2, and -2 with 96 to 97 weight percent of magnetic carrier particles having an average particle size of about 100 to 250 microns. formed things. Some of these developer compositions were released in October 1961.
It was used in a magnetic brush development process of the type described in U.S. Pat. No. 3,003,462, dated May 10, as follows. A magnetic field surrounding a rotatable non-magnetic cylinder with a magnetic device fixed therein maintains the developer composition in a loose, brush-like orientation during the development process. The magnetic carrier particles are attracted to the cylinder by the magnetic field, and the crosslinked toner particles are held to the carrier particles by the opposite electrostatic polarity. Before and during development, the crosslinked toner particles carry an opposite electrostatic charge to the carrier material due to triboelectricity induced by mutual frictional action. When this brush-like agglomerate, or magnetic brush composed of carrier and cross-linked toner, is drawn into contact with a photoconductive surface carrying an electrostatic image, the cross-linked toner particles acquire an opposite charge. It is electrostatically attracted to the latent image and forms a visible toner image corresponding to the electrostatic image. This developed crosslinked toner image is then transferred and fused to a plain paper receiving sheet. All of the crosslinked toner compositions described above form good quality images on plain paper receiver sheets. Although the present invention has been described above in detail based on particularly preferred embodiments, it will be fully understood that various changes and modifications can be made within the spirit of the present invention and the scope of the claims.

Claims (1)

[Scope of Claims] 1. A method for producing a developer comprising a fusible styrene-acrylic polymer, comprising: (a) (i) a non-crosslinked styrene-acrylic polymer having crosslinkable sites that can be crosslinked after formation by polymerization; (ii) forming a toner composition with a colorant; (b) non-crosslinked styrene having crosslinkable sites;
The acrylic polymer is crosslinked in the presence of a crosslinking compound to increase the melting point of the toner composition by at least 10°C compared to toner particles containing a corresponding styrene-acrylic polymer that has not reacted with the crosslinking compound. (c) the toner composition comprises at least 25% by weight, based on the total weight of the composition, of a crosslinked styrene-acrylic polymer;
The method has an effective fusing range of 100°C and a softening point of 40-65°C for fixing the electrostatic charge pattern by heated roller fusing. 2 The crosslinkable styrene-acrylic polymer is
40-90% by weight of styrene and 60-10% by weight of alkyl acrylates or methacrylates, including branched chain alkyls and cycloalkyl acrylates or methacrylates, in which the alkyl groups have up to 20 or more carbon atoms. The method according to claim 1.