CA1036409A - Electrostatographic toner composition - Google Patents
Electrostatographic toner compositionInfo
- Publication number
- CA1036409A CA1036409A CA208,944A CA208944A CA1036409A CA 1036409 A CA1036409 A CA 1036409A CA 208944 A CA208944 A CA 208944A CA 1036409 A CA1036409 A CA 1036409A
- Authority
- CA
- Canada
- Prior art keywords
- polymeric
- toner
- crystalline
- segment
- amorphous
- 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.)
- Expired
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/087—Binders for toner particles
- G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
- G03G9/08797—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature
-
- 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
- G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
- G03G9/08788—Block polymers
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- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Developing Agents For Electrophotography (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
ABSTRACT OF THE INVENTION
Electrostatographic toner materials having exception-ally desirable mechanical and thermal properties may be pre-pared by forming a finely divided mixture comprising a coloring material and a polymeric material which is block or graft copolymer consisting of at least one crystalline or crystalliz-able polymeric segment chemically linked to at least one amor-phous polymeric segment, said crystalline or crystallizable segment individually having a glass transition temperature of less than about 20°C and a melting point of at least about 45°C, and said amorphous segment individually having a glass transi-tion temperature less than the melting point of said crystalline or crystallizable segment. Toner materials prepared according to the present invention exhibit thermal and mechanical prop-erties which render them extremely useful in xerographic pro-cesses, particularly high speed processes.
Electrostatographic toner materials having exception-ally desirable mechanical and thermal properties may be pre-pared by forming a finely divided mixture comprising a coloring material and a polymeric material which is block or graft copolymer consisting of at least one crystalline or crystalliz-able polymeric segment chemically linked to at least one amor-phous polymeric segment, said crystalline or crystallizable segment individually having a glass transition temperature of less than about 20°C and a melting point of at least about 45°C, and said amorphous segment individually having a glass transi-tion temperature less than the melting point of said crystalline or crystallizable segment. Toner materials prepared according to the present invention exhibit thermal and mechanical prop-erties which render them extremely useful in xerographic pro-cesses, particularly high speed processes.
Description
11~3~Q~
B~ACKGROUND OF THE INVF,NTION f The present invention relates to electrostatographic toner compositions adapted for use in an electrophotographic imaging process, wherein the resinous component of the toner comprises a block or graft copolymer having crystalline and amorphous segments.
The formation and development of images on the surface of photoconductive materials by electrostatic means is well known. The basic electrostatographic process, as taught by C.F. Carlson in U.S. patent 2,297,691, involves placing a uni-form electrostatic charge on a photoconductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and dev-eloping the resulting electrostatic latent image by depositing on the image a finely divided electroscopic material referred to in the art as "toner". The toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image. This toner image may then be transferred to a copy sub-strate such as paper. The transferred image may subsequently be permanently affixed to the copy substrate such as by fusion wlth heat. Instead of forming the latent image by uniformly charging the photoconductive layer and then exposing the layer to a light and shadow image, one may form the latent image by directly charging an insulating layer, which can be either photoconductive or non-photoconductive, in image configuration.
The powder may be fixed directly to the insulating layer if desixed.
One of the important applications of electrostatography comprises its use in automatic copying machines for general ~ ~J36~
~' office use wherein an electrostatic latent image is developed using a developer composition comprising a carrier mixed with ~, fine particles of resinous toner, and the thus formed powder image is transferred to a copy substrate and then fixed thereon.
Considerable effort has been expended to provide suitable develo-pers and associated fixing techniques for modern high speed copying machines. The toner material used must have suitable electrostatic properties to permit attraction by the carrier and then selective attraction by the latent images. It must ~lO further be physically strong to permit constant recycling in a bouncing type of movement. The toner must further be resistant ~o blocking or aggregating at ordinary operating temperatures, but yet be capable of being readily fixed to the copy sheet.
Fixing techniques employing heat, pressure, solvents and various combinations thereof have been devised; however, each of these systems is subject to severe practical limitations which inhere in the systems themselves and also the toner compo-sitions heretofore availabIe. Whatever method of fixing is used, speed, effectiveness, and simplicity in operation are the principal, desirable characteristics to be obtained. The most commonly employed fixing techniques employ the use of heat alone or heat in combination with pressure. The toner materials employed must melt or block sufficiently above the ordinary operating temperatures of the machines involved to assure con-venient storage and handling. However, the materials must also melt at a practically low temperature to avoid excessively-high energy consumption and possible heat damage to the copy sub-strate or delicate machine parts.
It has long been recognized that one of the fastest and most positive methods of applying heat for fusing the powder -` 1.03~ 9 image to paper is to bring the powder image into direct contact with a hot surface, such as a heated flat plate or roller However, it was found that as a powder image is tackified by contact heating, part of the image carried by the copy sheet would stick to the hot surface so that as the next copy sheet was contacted with the hot sur~ace, the tackified image par-tially removed from the first sheet would partially transfer to the next sheet and, at the same time, part of the tackified image from said next sheet would adhere to the hot surface.
This p~enomenon is commonly referred to in the printing art as' "offset". For a given system, this upper temperature limit is referred to as the "hot offset temperature". Thus, contact heat fusers are inherently limited to the use of temperatures and toners which do not cause hot offset of the toner material.
Various types of polymeric materials have been pro-posed in the prior art for use as the resinous component in electrostatographic toners. U.S. Patent RE 25,136 teaches toner material based on polystyrene or copolymers of styrene with monomers such as alkyl methacrylates. British Patent 1,179,095 teaches toner material based on a combination of two polymeric materials, one of which polymeric materials has a glass transi-tion temperature of greater than 20C, and the other a glass transition temperature of at least 5C lower. These polymeric materials may be combined by physical admixture, or by forming block or graft copolymers. Other patents of interest in the electrostatographic toner area include U.S. Patents 2,788,288;
3,078,342; 3,391,082; 3,502,582; 3,510,338; 3,609,082 and 3,647,~96. As indicated above, these other toner materials based on amorphous polymers have not proven entirely satisfac-tory when used with contact heat fusers~
~3~9 While further advances in the art of fixing, includ-ing the use of offset reducing roller surfaces, have provided more suitable means to fuse toner images through the use of heat and pressure with decreased offset, these devices are still restricted to operate within close temperature toler-ances due to the narrow fusing latitudes obtainable with toner materials heretofore available. Exemplary of these contact fusing devices are those disclosed in U. S. Patents 3,256,002, 3,268,351, 3,291,466, 3,437,032, 3,498,596 and 3,539,161.
SUMMARY OF THE INVENTION
In accordance with one aspect of this invention there is provided a finely divided, particulate, electro-statographic toner composition comprising a uniform mixture of (a) a colorant material and (b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20C and a melting point of at least about 45 C, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
In accordance with another aspect of this invention there is provided in an electrophotographic imaging process including the steps wherein a particulate electrostatograph-ic toner composition is applied in image configuration to the surface of a recording member, and said recording member bearing said toner composition in image configuration is subjected to heat or heat and pressure sufficient to fuse ~ _4_ ., . . ,, , ~, ~
~(~36~q~9 said toner composition to the surface of said recording mem-ber, the improvement which comprises conducting said imaging process using a finely divided toner composition comprising a uniform mixture of: (a) a colorant material and (b) a poly-meric material, said polymeric material comprising a segment-ed copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copoly-mer having a glass transition temperature of less than about 20 C and a melting point of at least about 45C, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
In accordance with another aspect of this inven~ion there is provided an electrophotographic imaging process comprising the steps of subjecting the surface of a charged photoconductive insulating layer to a pattern of light and shadow such that an electrostatic latent image is formed on the surface of said layer, developing said latent image by contact of said surface with a developed composition compris-ing a mixture of carrier particles and toner material,trans-ferring the toner material in image configuration from said . surface to the surface of a recording member, and heating the surface of said recording member sufficient to fuse said : toner composition to the surface of said recording member, said toner material comprising a finely divided composition ~ comprising a uniform mixture of: (a) a colorant material ; and (b) a polymeric material, said polymeric material com-prising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said -4a-,~
~1~36~Q~
segmented copolymer having a glass transition temperature of less than about 20C, a melting point of at least about 45C, and an average molecular weight within the range of about 5,000 to 200,000 grams per moles, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
By way of supplementary explanation, it has now been discovered that electrostatographic toner material having exceptionally desirable mechanical and thermal properties may be prepared by forming a finely divided mixture compris-ing a coloring material and a polymeric material which is block or graft copolymer consisting of at least one cryst-alline or crystallizable polymeric segment chemically li'nked to at least one amorphous polymeric segment, sai~d crystalline or crystallizable segment individually having a glass trans-ition temperature of less than about 20C and a melting point of at least about 45C and said amorphous segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable segment. In the preferred embodiment, the glass transition temperature of both polymeric segments is less than about 0C and within the range of about 0 to -100C, and the melting point of the copolymer lies within the range of about 45 to about 150C. The amount of amorphous polymer present in the toner copolymers of this invention is prefer-ably within the range of about 10 to 90% by weight based on total polymer weight. Toner materials prepared according to the present invention exhibit thermal and mechan--4b--' ~ 36~(~9 ical properties which render them extremely useful in xerographi~
processes, particularly high speed processes involving heat con-tact fusing. The thermal properties of the instant toner ma-terials are such that they exhibit an extremely low latent heat of fusion while substantially retaining melting poLnt and melt crystallization characteristics of toner materials ~ased on ~rystalline or crystallizable homopolymers, thereby allowing for a broad latitude of fusing temperature without toner off-set.
DETAILED DESCRIPTIO~ OF THE I~VENTION :
In pressure roll fixing of electrostatographic toners, three interrelated parametexs of utmost importance in toner performance are: (1) the minimum fusing temperature, which is the minimum temperature required for fusing the toner; (2) the hot offset~ temperature, which is the minimum temperature at which the hot toner melt begins to adhere to the pressure mem-ber, i.e., the maximum temperature of operation which avoids this type of ixing failure; and (3) the fusing latitude, which is the operating range defined as the difference between the hot offset temperature and minimum fusing temperature.
Viscosity-temperature relationships for toner materials have been established, and it is found that a certain viscosity range is required for the onset of fusing. A second, somewhat lower, viscosity range has heen found to correspond to off-setting. The difference between these viscosity ranges is called the "fusing window". The fusing window depends to a great extent on specific machine parameters, such as components, ronfiguration~ speed, etc. For maximum range of fixing opera-tion, i.e., maximum fusing latitude, one requires a toner having a minimum temperature dependence on viscosity and 3364~
maximum traverse of the fusing window.
Whereas toner materials o the prior art containing amorphous polymeric material exhibit a minimum fusing tempera-ture usually in excess of 150C, and a fusing latitude in many ; 5 cases of less than 20C., it has been found that toner based on crystalline or crystallizable polymers specifically satisfy the aforementioned thermal and viscosity criteria. Crystalline polymers offer the advantages of relatively sharply defined melting points above which the polymer can be readily induced to flow and below which at the crystal~ization temperature (Tc) the polymer can be readily induced to harden. Crystalline or crystallizable polymers in general also exhibit less tendency to offset or adhere to fusion rollers even when temperatures of greater than 100C in the excess of the polymer melting point (Tm) are encountered during xerographic fusion. In addition, their mechanical properties are such that these materials are more resistant to degradation during processing into toner material.
Although the use of toner material based on crystalline or crystallizable polymers offers some advantages and flexibili-ty in terms of thermal and viscosity criteria particularly in high speed xerographic e~uipment, one disadvantage lies in the fact that an additional amount of heat energy is required to transform the polymer from a crystalline state to the state where the polymer will flow and adhere to the transfer substrate.
This heat energy requirement is known as the "Heat of Fusion"
and may be defined as the amount of energy necessary in trans-forming a polymer from a crystalline or a partially crystalline state to a completely disordered amorphous state without a change in temperature in the crystalline segments of the polymer.
The heat of fusion is directly relatable to the degree of crystallinity of a given polymer: the higher the crystallinity, 5 the greater the heat of ~usion, and the greater t~e amount of heat necessary to melt the polymer.
Thus, whexeas crystalline polymers offer certain advantages as indicated above, particularly when used as a toner component in a high speed xerographic prGcess, the addi-tional heat necessary for toner fusion tends to mitigate these advantages. In order to overcome the latent heat of fusion and impart the required flowability characteristics into a crystal-; line polymer such that good adhesion of the toner to the sub-strate will occur, it may be necessary to either heat the toner bearing recording medium to moderate temperature above TM for a period of time longer than might be desirable in a high speed operation, or subject the toner bearing substrate for a desir-ably short period of time to a temperature above TM which is in excess of that desirable. In the former case, speed is sacri-ficed; in the latter case, excessive heat and the concomitant disadvantages associated therewith may be encountered. In either case, the latent heat of fusion is a factor tending to mitigate somewhat the previously recited advantages inureing in toner based on crystalline polymers.
It is thus most advantageous to prepare a toner material which offers similar advantages of toner based on a crystalline or crystallizable polymer in terms of mechanical, physical, chemical and thermal properties, but which also exhibits a controllably minimal latent heat of fusion. This is accomplished according to the present invention by providing toner compositions comprising a block or graft copolymer con-taining at least one crystalline ur crystallizable polymeric segment chemically li~g~o at least one amorphous polymeric segment. Toner compositions based on such segmented copolymers have sharp well defined melting points with minimal heats of fusion, the heat of fusion of a particular copolymer being con-- 5 trolled as a function of the ratio of amorphous to crystalline segments present in the copolymer structure~ Of particular advantage is the fact that low heats of fusion can be achieved with a minimal effect on the melting point of the copolymer.
The block copolymers can be characterized as materials represented by any of the following generic schemes: [BA]n, [AB]n, [ABA]n, or [BAB~n, wherein n is a whole number equal to or greater than 1, A represents the amorphous polymeric segment and B repres-ents crystalline or crystallizable polymeric segment. Each seg-ment need not necessarily be homopolymeric. The individual block segments A and B may be linked directly to one another in head to tail fashion such as by covalent bonding resulting from sequential block copolymerization of the appropriate monomers or by coupling reaction between terminal functional groups present on different polymeric molecules. Alternatively, the block segments may be linked by means of difunctional coupling agents which remain in the block copolymer molecule, such as, for example, urethane linkages which would be formed by the reaction of hydroxyl terminated polymers with an organic diisocy-anate, or ester linkages formed by the reaction of hydroxy terminated polymers with dicarboxylic acids or carboxy termin-ated polymers with glycols, or other linkages formed by reac-tion of hydroxy terminated polymers with phosgene, dichlorodi-methyl silane and the like.
Where the block copolymers are formed using difunc-tional coupling agents, the above recited formula schemes for .
1al36~)9 such block copolymers should be considered generic to a speci-ic scheme wherein the coupling agent moiety is present in the block copolymer molecule connecting the A segment to the B seg-ment. In turn, each A or B segment depicted generically above may comprise a plurality of individual A segments coupled to-gether or a plurality o B segments coupled together. Thus, for example, the formula [BA]n should, for the purposes of the present invention, be considered generic to [Bl]-C-[Al] wherein each Bl and Al segment may consist of a single polymeric molecule or a plurality of polymeric molecules of similar structure coupled together, such as where [Bl] is B or [(B-c-)mB] and[A
is A or [A(-c-A)m], further whereln A and B are as specified above, m is a positive whole integer e~ual to 1 or greater, and c is the coupling agent moiety. The same holds true for the thxee other generic formula schemes recited above. Althou-~h the coupling techni~ue is preferred because it offers more pre-cise control over the amounts of each type of polymer lntro-duced into the polymer chain, it is to be emphasized that any polymerization techni~ue known to those skilled in the art affording the capability of preparing the tailor-made block copolymers of the present invention may be used.
The graft copolymers used as a toner ingredient according to the present invention can be categorized generic-ally as branched polymers exemplified by the following schemes:
(I) . . .AAaA~, ., (II) . . . BBBBBBBB. . .
B A
B A
B A
wherein A represents repeating momomeric units contained in the amorphous polymeric segment and B represents repeating _ g _ monomeric units cont ~ ~ ~ ~ e crystalline or crystallizable polymeric segment. As in the case of the block copolymers, the A and/or B segments may be homopolymeric or copolymeric. The grafted polymer chain may be present at any position along the S polymer backbone chain, including at the head or tail of the backbone polymer. In most instances a plurality of such grafted polymer chains may be present at various points along the back-bone. Where the crystalline or crystallizable polymer comprises the backbone chain, the degree of branching or grafting is pre-ferably minor in order to preserve the crystalline properties of the graft copolymer; where the grafted side chains comprise the crystalline or crystallizable polymer, then a larger number of side chains are desirable for the same reason. The graft copo-lymers may be prepared by techniques well known to those skilled in the ar~. Such techniques include creating a free radical site or sites along a polymer chain by irradiation or other technique with subse~uent polymerization of monomer in the pre-sence of the polymer; introducing active sites along the polymer chain by o~idation to create peroxide groups which act as free radical initiators with subsequent polvmerization of monomer;
and by coupling reactions performed by either introducing func-tional groups along the chain by metallation or other techniaues, or utilizing functional groups already present, which functional groups can be made to react either directly with a terminal functional group present in a second polymer or indirectly by means of coupling agents. As is the case with the block copoly-mers, the preferred techniaue for forming graft copolymers involves reacting preformed polymers because of the more precise control regarding polymer selection and degree of grafting.
Where the block or graft copolymers are prepared by -- 10 -- t -- ~036~
polymerizing a monomer or monomers in the presence of a pre-formed polymer, the choice of monomer, catalyst and polymeriza-tion conditions must be such that the polymerizing monomer will form a polymer having the desired crystalline, amorphous or iso-mer stFucture. Where the preformed polymer is amorphous, the -polymerizing monomer and polymerization conditions should be such as to lead to the formation of a crystalline or crystallizable polymer; and vice versa. Sequentially polymerized block copoly-mers are most conveniently prepared by solution polymerization using organo-metallic catalysts or the active Ziegler or Natta catalysts which give rise to the so-called "living polymers;"
graft copolymers are most conveniently prepared by solution or suspension polymerization involving dissolving or dispersing the backbone polymer in a liquid medium which medium contains graf-ting monomer, free radical initiator and polymerization catalyst.
The number average molecular weight of the copolymers employed in the toner compositions of the present invention should be within the range of about 5,000 to 200,000 g/mole for best results. At molecular weights of less than about 5,000 it is found that the copolymer may exhibit hot offsetting due to the low melt viscosity encountered at this low molecular weight;
above about 200,000 g/mole, the copolymer is more difficult to fuse or fix in the xerographic process. The preferred range for optimum hot melt properties is about 15,000 to 150,000 g/mole.
The individual amorphous or crystalline polymer segments forming the block or graft copolymer preferably have a number average molecular weight within the range of about 1,000 to 20,000 g~mole, with a preferred range of about 2,000 to 12,000 g/mole.
As indicated above, segmented copolymers derived from ; 30 monomers polymerized to form crystalline or crystallizable polymers having a cry~ a~ l~lne TM in the range of about 45 to `150C and a TG within the range of about 20 to -100C are particularly suitable for the purposes of this invention. Exam-ples of suitable genus and species polymers are: Polyesters, including'polyalkylene polyesters wherein the alkylene group ~ contains at least two carbon atoms such as polydecamethylene - sebacate, polydecamethylene succinate, polyethylene sebacate, polyethylene succinate, polyhe~amethylene sebacate, polyhex-amethylene suberate, polyhexamethylene succinate and the like;
aromatic polyesters such as poly-p-xylene adipate or poly-diethylene glycol terephthalate; polyvinyl esters and ethers such as polyvinyl ethyl ether, polyvinyl butyl ether, polyvinyl
B~ACKGROUND OF THE INVF,NTION f The present invention relates to electrostatographic toner compositions adapted for use in an electrophotographic imaging process, wherein the resinous component of the toner comprises a block or graft copolymer having crystalline and amorphous segments.
The formation and development of images on the surface of photoconductive materials by electrostatic means is well known. The basic electrostatographic process, as taught by C.F. Carlson in U.S. patent 2,297,691, involves placing a uni-form electrostatic charge on a photoconductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and dev-eloping the resulting electrostatic latent image by depositing on the image a finely divided electroscopic material referred to in the art as "toner". The toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image. This toner image may then be transferred to a copy sub-strate such as paper. The transferred image may subsequently be permanently affixed to the copy substrate such as by fusion wlth heat. Instead of forming the latent image by uniformly charging the photoconductive layer and then exposing the layer to a light and shadow image, one may form the latent image by directly charging an insulating layer, which can be either photoconductive or non-photoconductive, in image configuration.
The powder may be fixed directly to the insulating layer if desixed.
One of the important applications of electrostatography comprises its use in automatic copying machines for general ~ ~J36~
~' office use wherein an electrostatic latent image is developed using a developer composition comprising a carrier mixed with ~, fine particles of resinous toner, and the thus formed powder image is transferred to a copy substrate and then fixed thereon.
Considerable effort has been expended to provide suitable develo-pers and associated fixing techniques for modern high speed copying machines. The toner material used must have suitable electrostatic properties to permit attraction by the carrier and then selective attraction by the latent images. It must ~lO further be physically strong to permit constant recycling in a bouncing type of movement. The toner must further be resistant ~o blocking or aggregating at ordinary operating temperatures, but yet be capable of being readily fixed to the copy sheet.
Fixing techniques employing heat, pressure, solvents and various combinations thereof have been devised; however, each of these systems is subject to severe practical limitations which inhere in the systems themselves and also the toner compo-sitions heretofore availabIe. Whatever method of fixing is used, speed, effectiveness, and simplicity in operation are the principal, desirable characteristics to be obtained. The most commonly employed fixing techniques employ the use of heat alone or heat in combination with pressure. The toner materials employed must melt or block sufficiently above the ordinary operating temperatures of the machines involved to assure con-venient storage and handling. However, the materials must also melt at a practically low temperature to avoid excessively-high energy consumption and possible heat damage to the copy sub-strate or delicate machine parts.
It has long been recognized that one of the fastest and most positive methods of applying heat for fusing the powder -` 1.03~ 9 image to paper is to bring the powder image into direct contact with a hot surface, such as a heated flat plate or roller However, it was found that as a powder image is tackified by contact heating, part of the image carried by the copy sheet would stick to the hot surface so that as the next copy sheet was contacted with the hot sur~ace, the tackified image par-tially removed from the first sheet would partially transfer to the next sheet and, at the same time, part of the tackified image from said next sheet would adhere to the hot surface.
This p~enomenon is commonly referred to in the printing art as' "offset". For a given system, this upper temperature limit is referred to as the "hot offset temperature". Thus, contact heat fusers are inherently limited to the use of temperatures and toners which do not cause hot offset of the toner material.
Various types of polymeric materials have been pro-posed in the prior art for use as the resinous component in electrostatographic toners. U.S. Patent RE 25,136 teaches toner material based on polystyrene or copolymers of styrene with monomers such as alkyl methacrylates. British Patent 1,179,095 teaches toner material based on a combination of two polymeric materials, one of which polymeric materials has a glass transi-tion temperature of greater than 20C, and the other a glass transition temperature of at least 5C lower. These polymeric materials may be combined by physical admixture, or by forming block or graft copolymers. Other patents of interest in the electrostatographic toner area include U.S. Patents 2,788,288;
3,078,342; 3,391,082; 3,502,582; 3,510,338; 3,609,082 and 3,647,~96. As indicated above, these other toner materials based on amorphous polymers have not proven entirely satisfac-tory when used with contact heat fusers~
~3~9 While further advances in the art of fixing, includ-ing the use of offset reducing roller surfaces, have provided more suitable means to fuse toner images through the use of heat and pressure with decreased offset, these devices are still restricted to operate within close temperature toler-ances due to the narrow fusing latitudes obtainable with toner materials heretofore available. Exemplary of these contact fusing devices are those disclosed in U. S. Patents 3,256,002, 3,268,351, 3,291,466, 3,437,032, 3,498,596 and 3,539,161.
SUMMARY OF THE INVENTION
In accordance with one aspect of this invention there is provided a finely divided, particulate, electro-statographic toner composition comprising a uniform mixture of (a) a colorant material and (b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20C and a melting point of at least about 45 C, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
In accordance with another aspect of this invention there is provided in an electrophotographic imaging process including the steps wherein a particulate electrostatograph-ic toner composition is applied in image configuration to the surface of a recording member, and said recording member bearing said toner composition in image configuration is subjected to heat or heat and pressure sufficient to fuse ~ _4_ ., . . ,, , ~, ~
~(~36~q~9 said toner composition to the surface of said recording mem-ber, the improvement which comprises conducting said imaging process using a finely divided toner composition comprising a uniform mixture of: (a) a colorant material and (b) a poly-meric material, said polymeric material comprising a segment-ed copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copoly-mer having a glass transition temperature of less than about 20 C and a melting point of at least about 45C, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
In accordance with another aspect of this inven~ion there is provided an electrophotographic imaging process comprising the steps of subjecting the surface of a charged photoconductive insulating layer to a pattern of light and shadow such that an electrostatic latent image is formed on the surface of said layer, developing said latent image by contact of said surface with a developed composition compris-ing a mixture of carrier particles and toner material,trans-ferring the toner material in image configuration from said . surface to the surface of a recording member, and heating the surface of said recording member sufficient to fuse said : toner composition to the surface of said recording member, said toner material comprising a finely divided composition ~ comprising a uniform mixture of: (a) a colorant material ; and (b) a polymeric material, said polymeric material com-prising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said -4a-,~
~1~36~Q~
segmented copolymer having a glass transition temperature of less than about 20C, a melting point of at least about 45C, and an average molecular weight within the range of about 5,000 to 200,000 grams per moles, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
By way of supplementary explanation, it has now been discovered that electrostatographic toner material having exceptionally desirable mechanical and thermal properties may be prepared by forming a finely divided mixture compris-ing a coloring material and a polymeric material which is block or graft copolymer consisting of at least one cryst-alline or crystallizable polymeric segment chemically li'nked to at least one amorphous polymeric segment, sai~d crystalline or crystallizable segment individually having a glass trans-ition temperature of less than about 20C and a melting point of at least about 45C and said amorphous segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable segment. In the preferred embodiment, the glass transition temperature of both polymeric segments is less than about 0C and within the range of about 0 to -100C, and the melting point of the copolymer lies within the range of about 45 to about 150C. The amount of amorphous polymer present in the toner copolymers of this invention is prefer-ably within the range of about 10 to 90% by weight based on total polymer weight. Toner materials prepared according to the present invention exhibit thermal and mechan--4b--' ~ 36~(~9 ical properties which render them extremely useful in xerographi~
processes, particularly high speed processes involving heat con-tact fusing. The thermal properties of the instant toner ma-terials are such that they exhibit an extremely low latent heat of fusion while substantially retaining melting poLnt and melt crystallization characteristics of toner materials ~ased on ~rystalline or crystallizable homopolymers, thereby allowing for a broad latitude of fusing temperature without toner off-set.
DETAILED DESCRIPTIO~ OF THE I~VENTION :
In pressure roll fixing of electrostatographic toners, three interrelated parametexs of utmost importance in toner performance are: (1) the minimum fusing temperature, which is the minimum temperature required for fusing the toner; (2) the hot offset~ temperature, which is the minimum temperature at which the hot toner melt begins to adhere to the pressure mem-ber, i.e., the maximum temperature of operation which avoids this type of ixing failure; and (3) the fusing latitude, which is the operating range defined as the difference between the hot offset temperature and minimum fusing temperature.
Viscosity-temperature relationships for toner materials have been established, and it is found that a certain viscosity range is required for the onset of fusing. A second, somewhat lower, viscosity range has heen found to correspond to off-setting. The difference between these viscosity ranges is called the "fusing window". The fusing window depends to a great extent on specific machine parameters, such as components, ronfiguration~ speed, etc. For maximum range of fixing opera-tion, i.e., maximum fusing latitude, one requires a toner having a minimum temperature dependence on viscosity and 3364~
maximum traverse of the fusing window.
Whereas toner materials o the prior art containing amorphous polymeric material exhibit a minimum fusing tempera-ture usually in excess of 150C, and a fusing latitude in many ; 5 cases of less than 20C., it has been found that toner based on crystalline or crystallizable polymers specifically satisfy the aforementioned thermal and viscosity criteria. Crystalline polymers offer the advantages of relatively sharply defined melting points above which the polymer can be readily induced to flow and below which at the crystal~ization temperature (Tc) the polymer can be readily induced to harden. Crystalline or crystallizable polymers in general also exhibit less tendency to offset or adhere to fusion rollers even when temperatures of greater than 100C in the excess of the polymer melting point (Tm) are encountered during xerographic fusion. In addition, their mechanical properties are such that these materials are more resistant to degradation during processing into toner material.
Although the use of toner material based on crystalline or crystallizable polymers offers some advantages and flexibili-ty in terms of thermal and viscosity criteria particularly in high speed xerographic e~uipment, one disadvantage lies in the fact that an additional amount of heat energy is required to transform the polymer from a crystalline state to the state where the polymer will flow and adhere to the transfer substrate.
This heat energy requirement is known as the "Heat of Fusion"
and may be defined as the amount of energy necessary in trans-forming a polymer from a crystalline or a partially crystalline state to a completely disordered amorphous state without a change in temperature in the crystalline segments of the polymer.
The heat of fusion is directly relatable to the degree of crystallinity of a given polymer: the higher the crystallinity, 5 the greater the heat of ~usion, and the greater t~e amount of heat necessary to melt the polymer.
Thus, whexeas crystalline polymers offer certain advantages as indicated above, particularly when used as a toner component in a high speed xerographic prGcess, the addi-tional heat necessary for toner fusion tends to mitigate these advantages. In order to overcome the latent heat of fusion and impart the required flowability characteristics into a crystal-; line polymer such that good adhesion of the toner to the sub-strate will occur, it may be necessary to either heat the toner bearing recording medium to moderate temperature above TM for a period of time longer than might be desirable in a high speed operation, or subject the toner bearing substrate for a desir-ably short period of time to a temperature above TM which is in excess of that desirable. In the former case, speed is sacri-ficed; in the latter case, excessive heat and the concomitant disadvantages associated therewith may be encountered. In either case, the latent heat of fusion is a factor tending to mitigate somewhat the previously recited advantages inureing in toner based on crystalline polymers.
It is thus most advantageous to prepare a toner material which offers similar advantages of toner based on a crystalline or crystallizable polymer in terms of mechanical, physical, chemical and thermal properties, but which also exhibits a controllably minimal latent heat of fusion. This is accomplished according to the present invention by providing toner compositions comprising a block or graft copolymer con-taining at least one crystalline ur crystallizable polymeric segment chemically li~g~o at least one amorphous polymeric segment. Toner compositions based on such segmented copolymers have sharp well defined melting points with minimal heats of fusion, the heat of fusion of a particular copolymer being con-- 5 trolled as a function of the ratio of amorphous to crystalline segments present in the copolymer structure~ Of particular advantage is the fact that low heats of fusion can be achieved with a minimal effect on the melting point of the copolymer.
The block copolymers can be characterized as materials represented by any of the following generic schemes: [BA]n, [AB]n, [ABA]n, or [BAB~n, wherein n is a whole number equal to or greater than 1, A represents the amorphous polymeric segment and B repres-ents crystalline or crystallizable polymeric segment. Each seg-ment need not necessarily be homopolymeric. The individual block segments A and B may be linked directly to one another in head to tail fashion such as by covalent bonding resulting from sequential block copolymerization of the appropriate monomers or by coupling reaction between terminal functional groups present on different polymeric molecules. Alternatively, the block segments may be linked by means of difunctional coupling agents which remain in the block copolymer molecule, such as, for example, urethane linkages which would be formed by the reaction of hydroxyl terminated polymers with an organic diisocy-anate, or ester linkages formed by the reaction of hydroxy terminated polymers with dicarboxylic acids or carboxy termin-ated polymers with glycols, or other linkages formed by reac-tion of hydroxy terminated polymers with phosgene, dichlorodi-methyl silane and the like.
Where the block copolymers are formed using difunc-tional coupling agents, the above recited formula schemes for .
1al36~)9 such block copolymers should be considered generic to a speci-ic scheme wherein the coupling agent moiety is present in the block copolymer molecule connecting the A segment to the B seg-ment. In turn, each A or B segment depicted generically above may comprise a plurality of individual A segments coupled to-gether or a plurality o B segments coupled together. Thus, for example, the formula [BA]n should, for the purposes of the present invention, be considered generic to [Bl]-C-[Al] wherein each Bl and Al segment may consist of a single polymeric molecule or a plurality of polymeric molecules of similar structure coupled together, such as where [Bl] is B or [(B-c-)mB] and[A
is A or [A(-c-A)m], further whereln A and B are as specified above, m is a positive whole integer e~ual to 1 or greater, and c is the coupling agent moiety. The same holds true for the thxee other generic formula schemes recited above. Althou-~h the coupling techni~ue is preferred because it offers more pre-cise control over the amounts of each type of polymer lntro-duced into the polymer chain, it is to be emphasized that any polymerization techni~ue known to those skilled in the art affording the capability of preparing the tailor-made block copolymers of the present invention may be used.
The graft copolymers used as a toner ingredient according to the present invention can be categorized generic-ally as branched polymers exemplified by the following schemes:
(I) . . .AAaA~, ., (II) . . . BBBBBBBB. . .
B A
B A
B A
wherein A represents repeating momomeric units contained in the amorphous polymeric segment and B represents repeating _ g _ monomeric units cont ~ ~ ~ ~ e crystalline or crystallizable polymeric segment. As in the case of the block copolymers, the A and/or B segments may be homopolymeric or copolymeric. The grafted polymer chain may be present at any position along the S polymer backbone chain, including at the head or tail of the backbone polymer. In most instances a plurality of such grafted polymer chains may be present at various points along the back-bone. Where the crystalline or crystallizable polymer comprises the backbone chain, the degree of branching or grafting is pre-ferably minor in order to preserve the crystalline properties of the graft copolymer; where the grafted side chains comprise the crystalline or crystallizable polymer, then a larger number of side chains are desirable for the same reason. The graft copo-lymers may be prepared by techniques well known to those skilled in the ar~. Such techniques include creating a free radical site or sites along a polymer chain by irradiation or other technique with subse~uent polymerization of monomer in the pre-sence of the polymer; introducing active sites along the polymer chain by o~idation to create peroxide groups which act as free radical initiators with subsequent polvmerization of monomer;
and by coupling reactions performed by either introducing func-tional groups along the chain by metallation or other techniaues, or utilizing functional groups already present, which functional groups can be made to react either directly with a terminal functional group present in a second polymer or indirectly by means of coupling agents. As is the case with the block copoly-mers, the preferred techniaue for forming graft copolymers involves reacting preformed polymers because of the more precise control regarding polymer selection and degree of grafting.
Where the block or graft copolymers are prepared by -- 10 -- t -- ~036~
polymerizing a monomer or monomers in the presence of a pre-formed polymer, the choice of monomer, catalyst and polymeriza-tion conditions must be such that the polymerizing monomer will form a polymer having the desired crystalline, amorphous or iso-mer stFucture. Where the preformed polymer is amorphous, the -polymerizing monomer and polymerization conditions should be such as to lead to the formation of a crystalline or crystallizable polymer; and vice versa. Sequentially polymerized block copoly-mers are most conveniently prepared by solution polymerization using organo-metallic catalysts or the active Ziegler or Natta catalysts which give rise to the so-called "living polymers;"
graft copolymers are most conveniently prepared by solution or suspension polymerization involving dissolving or dispersing the backbone polymer in a liquid medium which medium contains graf-ting monomer, free radical initiator and polymerization catalyst.
The number average molecular weight of the copolymers employed in the toner compositions of the present invention should be within the range of about 5,000 to 200,000 g/mole for best results. At molecular weights of less than about 5,000 it is found that the copolymer may exhibit hot offsetting due to the low melt viscosity encountered at this low molecular weight;
above about 200,000 g/mole, the copolymer is more difficult to fuse or fix in the xerographic process. The preferred range for optimum hot melt properties is about 15,000 to 150,000 g/mole.
The individual amorphous or crystalline polymer segments forming the block or graft copolymer preferably have a number average molecular weight within the range of about 1,000 to 20,000 g~mole, with a preferred range of about 2,000 to 12,000 g/mole.
As indicated above, segmented copolymers derived from ; 30 monomers polymerized to form crystalline or crystallizable polymers having a cry~ a~ l~lne TM in the range of about 45 to `150C and a TG within the range of about 20 to -100C are particularly suitable for the purposes of this invention. Exam-ples of suitable genus and species polymers are: Polyesters, including'polyalkylene polyesters wherein the alkylene group ~ contains at least two carbon atoms such as polydecamethylene - sebacate, polydecamethylene succinate, polyethylene sebacate, polyethylene succinate, polyhe~amethylene sebacate, polyhex-amethylene suberate, polyhexamethylene succinate and the like;
aromatic polyesters such as poly-p-xylene adipate or poly-diethylene glycol terephthalate; polyvinyl esters and ethers such as polyvinyl ethyl ether, polyvinyl butyl ether, polyvinyl
2-methoxyethyl ether, polyvinyl stearate and the like, poly- ~
sulfides and sulfones such as polydecamethylene sulfide, poly-hexamethylene sulfide, polytetramethyléne'sul~one and the ike;
polyethers such as polybutadiene oxide, polyethylene oxide, polypropylene oxide and the like; polyepihalohydrins such as polyepifluorohydrin; polyenes including cis and trans polydienes such as cis 1, 4 polybutadiene and 1,2 trans polybutadiene;
polyolefins such as poly-l-pe'ntene, poly-l-hexadecene, poly-butene, poly-3-methyl-1-butene and the like; cellulose poly-mers such as cellulose tricaprate; polyacrylates such as poly-isobutyl acrylate; polyacids; polyamides; polyurethanes; and like polymers. Copolymers derived from monomers constituting two or more of the above polymers may also be used. Particul-arly preferred as crystalline segments in the block or graft copolymers are those polymers and copolymers having a TM within the range of about 55C to'about 120C.
~he amorphous segment of the block or graft copolymers may similarly be selected from a wide variety of polymeric ~36~
materials having a TG less than the TM f the crystalline polym~r ~egment with which it is to be associated in the block or gra~t copolymer The TG f the amorphous segment is preferably less the 0C. Examples of suitable amorphous polymers include atactic polymers derived from the same or different monomers or monomer isomers used to form the crystalline or crystallizable segment of the copolymer recited above, said monomers polymer-ized under conditions such that atactic rather than isotactic structure results. Suitable classes of amorphous polymers in-~10 clude polyvinyl ethers; atactic polyolefins: polyacrylates;
polyoxides such as polypropylene oxide; polysulfides; unsymmet-rically branched polyesters and polyamides; aliphatic polyurethanes;
and like materials.
It has been further found that electrostatographic or triboelectric properties of the present toner materials may be optimized and best controlled by employing isomeric copolymers, that is, copolymers wherein the crystalline and amorphous seg-ments have identical chemical compositions but, of course, different chemical structures. Examples of such copolymers would be block or graft copolymers wherein the crystalline segment comprises polybutene-l or -2, and the amorphous segment comprises polyisobutylene; copolymers wherein the crystalline segment is polyhexamethylene sebacate and the amorphous segment is poly-(2-methyl, 2-ethyl, 1,3-propylene sebacate).. Other combinations include isotactic poly tvinyl n-propyl ether) and atactic poly (vinyl isopropyl ether; poly (trimethylene sulfide) and poly (propylene sulfide); poly (hexamethylene oxide) and atactic poly (vinyl butyl ether); isotactic poly (isobutyl acrylate) and atactic poly (n-butyl acrylate). Other isomeric combinations will occur to those skilled in the art.
. .
~64q~ ~
As indicated above, ~or best results the segmented co-polymers should exhibit a Tm within the range of about 45C to a~out 150C and a TG within the range of about 20C to -lOO~C.
In order to avoid the possibility of blocking under extreme conditions, it may be desirable to select crystalline and amor-phous segments such that the copolymers have a Tm in excess of about 55C and a TG of less than 0C.
The block or graft copolymers may be ~abricated into electrostatographic toner using any ~f the known techniques of the prior art by mixing the copolymers with a colorant material.
Mixing may be accomplished by dispersing the colorant in the melted copolymer, hardening the polymer and pulverizing the composition in a device such as a jet or hammermill to form it into small particles. Alternatively, mixing may be carried out by combining the colorant with a solution, dispersion or latex of the copolymer, followed by recovery of the copolymer/colorant mixture in finely divided form by spray drying techniques.
Suitable methods of mixing are more thoroughly described in U.S. Patent 3,502,582. The average particle size of the processed toner should be within the range of about 1 to 30 microns, pre-ferably between about 3 to 15 microns. A subsequent screening or slzing operation may be necessary to produce a toner having this particle size distribution.
The colorant material used in preparing the toner composition may include any pigment or water or organic solvent soluble dye. The most common pigments used in electrostato-graphic toner materials are finely divided carbon black, cyan, magenta and yellow pigments. The most common dyes are the acid, basic and dispersed dyes of suitable color as are known in the art. Typical examples of suitable colorants are discussed in 6~619 U.S. Patent 3,502,582. The pigment or dye should be present in the amount effective to render the toner highly colored so that it will form a clearly visible image on a recording member. Pre-ferably, for sufficient color density, the pigment is employed in an amount from about 1% to about 20% by weight, based on the total weight of the colored toner. If the toner colorant employ-ed is a dye, quantities substantially smaller than about 1% by weight may be used.
q~e toner composition may be formulated into an elec-trostatographic developer composition by combining the finely divided toner with a suitable carrier material such that the toner forms a coating on the carr}er. The toner and carrier material may be premixed or mixed inside the developer region of the xerographic machine. Where the development process in the well known magnetic brush process, the carrier material will be a magnetically attractive material such as finely divided iron particles of about 60 to 120 mesh size. For other than magnetic brush development , the carrier material may be of any of the known particulate substances exhibiting appropriate tri-boelectric effects such that the carrier particles impart a charge to the finer toner whereby the toner adheres to and coats each carrier particle. Examples of suitable carriers are inor-ganic salts, glass, silicon and other materlals such as disclosed in the aforementioned U.S. Patent 3,502,582. The particle size of the carrier should be significantly greater than the toner, preferably within the range of about 50 to 1000 microns. The toner is most effectively employed at a level from about 0.5 to 10 parts by weight per 100 parts by weight of carrier material.
The toner and developer compositions of the present in~ention may also contain any of the additives known to be ~1~36~q~9 included in such compositions such as lubrication aids, anti-oxidants, sensitizing agents, polymeric or non-polymeric plasti-cizers, and the like.
Description of the Preferred Embodiment S The following specific embodiment illustrates the preparation of toner ma-terial wherein the polymeric component comprises an isomeric block copolyester prepared by coupling crystalline poly (hexamethylene sebacate) [poly HMS] and amorphous poly (2-methyl-2-ethyl-1,3,-propylene sebacate) [poly MEPS] using hexamethylene diisocyanate as the coupling agent whereby urethane linkages are formed. The block copolyester was prepared by initially individually synthesizing poly~MS and poly MEPS, and then subjecting a mixture of these homopolymers to a coupling reaction as hereinafter described.
ExamPle 1 Crystalline poly (hexamethylene sebacate) was prepared using a kettle equipped with a stirrer, nitrogen gas inlet tube, thermometer and condenser by reacting sebacic acid with 1,6 hexamethylene glycol in the presence of a p-toluenesulfonic acid catalyst as follows: sebacic acid and hexamethylene glycol were added to the reaction kettle in a respective 1.0 to 1.1 molar ratio along with 0.5 wt % p-toluenesulfonic acid. The 10 mole % excess of glycol was used to ensure the predominant presence of hydroxyl end groups in the reaction product. The mixture was heated to 165C while stirring. At 165C, an amount of xylene was added to assist refluxing and this temperature was main-tained until water evolution ceased (4 hrs.). Afterwards, the condensers were removed and the excess glycol and catalyst were removed by sparging with nitrogen for 0.5 hours at 165C. On cooling to room temperature, the poly (hexamethylene sebacate) ~ 16 -lQ36~0~
crystallized into an off-white solid. ~ext, the poly ~HMS) from above was purified by precipitation from a benzene solution into met~anol using techniques well known in the art. The precipi-tated poly (HMS) was collected by filtration and dried in vacuo.
Analytical data on this purified material indicate an acid number of 1.06, an hydroxyl number of 34.4, an ~n of 3165 g/mole, an MWD (MW/M~) of 1.41 by GPC in chloroform, a glass transition temperature of a~out -62C and a crystalline melting point of about 65C.
Example 2 Amorphous poly (2-methyl-2-ethyl-1,3-propylene sebacate) was prepared by reacting sebacic acid and a 10 mole % excess of 2-methyl-2-ethyl~1,3-propylene glycol in the presence of 0.5 weight % p-toluenesulfonic acid in the same manner as in Example 1. On cooling to room temperature after the polymerization, the poly (MEPS) remained as a clear, tacky fluid. Analysis indicates it has an acid number of 2.40, an hydroxyl number of 19.4, an ~n of 5150 g/mole, an MWD of 1,87 by GPC in chloroform, and a glass transition temperature of about -61C.
Example 3 A block copolyester was prepared by coupling the hydroxy terminated poly (HMS) prepared in Example 1 and the hydroxy terminated poly (MEPS) prepared in Example 2 using hexamethylene diisocyanate as the coupling agent according to the following procedure: three parts by weight of poly (HMS) of Example 1 were mixed with one part by weight of poly (MEPS) of Example 2 in a reaction kettle equipped with a stirrer, nitrogen gas inlet tube, thermometer and condenser. The mixture was heated to 135C with stirring, and hexamethylene diisocyanate 1~364~9 was added at a level of 4.5% by weight of the fluid polymeric mixture. The temperature was maintained at 135C. Within 10 minutes the VisCOslty was such that the polymeric mass began to envelop and climb the stirrer. The coupling reaction was terminated after one hour and the copolymer was dissoIved in benzene and precipitated with stirring into methanol. The precipitate was collected by filtration, washed thoroughly with methanol and dried in vacuo. A yield of about 89% was realized from this coupling reaction. The block copolyester was analyzed by Nuclear Magnetic Resonance to contain 78.6% poly (HMS) and 21.4% poly (MEPS). It had an intrinsic viscosity in chloroform of 0.90 dl/g at 25C, a molecular weight believed to be about 45,000 1 15,000 g/mole, crystalline melting point of about 63C, and a glass transition temperature of about -60C.
Although the structure of the block copolymer molecules produced according to Example 3 is not precisely known, it is believed that because of the predominant presence of segments of polymerized (HMS) in the block copolymer, the copolymer statistically comprises a plurality of repeating crystalline poly HMS segments connected by urethane linkages, said repeating segments in turn connected by urethane linkages with the amor-phous poly (MEPS) segments at various random points along the block copolymer chain, such as illustrated in the following scheme:
.... B-c-B-c-B-c-A-c-B................ wherein B represents polymerized (HMS) A represents polymerized (MEPS) O H H O
and C represents -0-C-N (C H2)6~-C-0-This segment of structure conforms to the generic structure BAB, a species of which generic structure for this copolymer is ' [Bll-c-[Al] c-[Bll], wherein 103640~
Bl is [-(B-c-)2B]
Al is A
,and B 1 is B
Example 4 '~
A xerographic toner material was prepared by forming a mixture of the block copolyester of Exarnple 3 and a finely divided pigment grade carbon black.
A mixture comprising 95 parts by weight of the block copolyester of Example 3, and 5 parts by weight of Molocco H
,, 10 carbon black was formed by heating the copolyester to a temper-ature above its melting point, dispersing therein the carbon black, and mixing until a uniform dispersion of the carbon black in the block copolyester was obtained. The mixture was then guick cooled to a temperature below the melting point of the block copolyester.
Finely divided toner material having an average particle size in the order of about 20 microns was prepared by comminuting the above mixture first in a Fitz mill and subse-~uently in a jet pulverizer.
The toner was tested by employing it as the toner in a "Xerox 3600" copy machine embodying a contact heat fusing de-vice and found to produce very satisfactory copies without toner offset on the fusing roll.
Exam~les 5 - 11 Several additional samples of isomeric block copoly-esters having various ratios of poly (HMS) and poly (MEPS) were prepared ~y coupling the poly (HMS) of Example 1 and the pol,y (MEPS) of Example 2 using various coupling agents. Synthesis data for these copolyesters is shown in Table 1.
The block copolyesters of Examples 5, 7, 9~ 10 and 11 : !~ ~l)3f~9 .
o C~ U C~
U o o o o o o o o o oo r~ In In ~
_ ~ ~ n E~
OD ~ ~ ~D a) o ~q ~ ~ ~ o r~ o o~ o~
. ~ o U~ U~
o ~C~ .
~: .
~ o o o o ~ ~
_I ,~ o ~ ~I r- o ~r .~
c~ ~ N t`l I
O O V O ~`1 0 , ~C ~ ~ rl Z O ~ ~
~ u ~--H
. I ~ ~ ~ ~ ~ ~
I~ ~`l ~ ~ ~ ~ d' ~ ' V U U U C~ ~ U
I -- O ~ ~ ~ U ~
,~ 1 U
m E~ ..
., .,, "., ,,, , u~ a~
. ~ o ~ ~ ~ ~ ~ In ~:
u~ ~D ~ ~ O O
n O ~
. Q
~ O CO CO OD ~.
o ~ ~ ~ ~ ~ ~
p~ ~ ~
ol :
.
`
l x x x x x x x u~ ~ ~ ~ ~ ~ F~ ~1 ~ ~i ~q~36~ f were prepared by the method of Example 3; with regard to the block copolyesters of Examples 6 and 8, the procedure of Example 3 was modified somewhat in that refluxing was carried out in chlorobenzene (132C) containing a small amount of pyridine. General techniques for preparing linear copolyesters using coupling agents are known in the art as, for example, disclosed in U.S. Patent 2,691,006.
The copolymers of Examples 5 - 11 were each processed into toner material by the method of Example ~ and each per-formed satisfactorily when used in a xerographic machine.
As indicated above, toner materials based on the seg-mented copolymers of the present invention exhibit minimal latent heats of fusion and at the same time the sharp, well defined melting points desirable in a toner material. This ; 15 may be illustrated by a comparison of the latent heats of fusion PHU - in calories/gm.) and melting points (Tm) for a plurality of polymer samples containing polymerized hexamethy-lene sebacate (E~S) and polymerized 2 methyl-2-ethyl-1,3-propylene sebacate ~MEPS).
Example 12 A series of homopolymer blends having various weight ratios between about 20-80% oE poly (HMS) and poly (MEPS) were prepared by forming intimate admixtures of the poly (HMS) pre-pared according to Example 1 and the poly (MEPS) prepared according to Example 2.
A series of block copolymer samples having various weight ratios between about 20-80% of poly (HMS) and poly (MEPS) were prepared according to the process of Example 3.
A series of random copolymers also having various weight ratios between about 20-80% of polymerized HMS and poly-merized MEPS were prepared by a process similar to that described in Example 1 by reacting simultaneously a mixture of 1, 6 hexamethylene glycol, 2-methyl-2-ethyl-1,3 propylene glycol and sebacic acidO Various copolymer compositions were achieved by alterning, systematically, the molar ratio of the two diols in the condensation reaction with sebacic acid. The copolymers so prepared exhibited Mn values within the range of about 2200 to 3600 g/mole.
Samples of each type of polymer composition for various levels of polymerized HMS content were evaluated for latent heat of fusion and crystalline melting point data, the results plotted, and the plots interpolated at 80%, 60%, 40%, and 20%
HMS content. Results are shown in Table 2.
% Random Homopolymer Block HMS CopolYmer Blend ~polymer Tm ~ Hu Tm d H T~ ~Hu 100% 65C 30 65C 30 65C 30 80% 57C ~10 64C 25 63C 17 60% 42C - 62C 18 61C 11 40% 22C - 62C 12 56C 7 20% 0C - 61C 6 5~C 6 As can be seen from Table 2, the melting point of the random copolymers drops off rapidly as the % HMS in the random copolymer is decreased with a corresponding increase in % MEPS. 5 Below about 60% ~S, the copolymers are a viscous fluid unsuit-able for use in a toner composition. With the homopolymer blends, the lowering of Tm is much less severe, but~ Hu is found to drop off in almost direct proportion to the amount of poly (HMS) in the blend. With the block copolymers, the lower-~3~ 9 ing of Tm is somewhat greater than in the blend, but still quite acceptable for toner use, but most significantly the drop in u is much higher than in comparable samples of the blend.
Thus, considerably less heat energy is required to melt or fuse toner based on the block copolymers than is required to melt toner based on the homopolymer blend.
~lthough the toner ~omposition of the present lnven-tion may be used in electrophotographic processes embodying any of the well known techniques of image fixation or fusing such as radiation, vapor, or liquid fusing, it is employed most advan-tageously in processes involving contact fusing, as discussed above, or flash fusing such as for example disclosed in U.S.
Patents 3,465,203, 3,474,223, and 3,529,129. In each of these processes, exposure of the image recording medium bearing the powdered toner image, usually paper, to a source of hea~ is for an extremely llmited tlme duration. In contact fusing, a moving recording medium is exposed to heat while the medium passes through a nlp formed by a heated pressure roller and a second support roller. Wlth radiant flash fusing, the recording medium is exposed to heat energy in the form of electromagnetic waves generated usually by a gas lamp, such as a xenon lamp, for a period of timed measured in milliseconds. With each of these processes, a maximum amount of heat energy sufficient to properly fuse the toner without scortching the recording medium is re-quired over a short period of time. It is thus evident that the toner compositions of the present invention having sharp well defined melting points and controllably minimal latent heats of fusion respond particularly well for use in processes involving such fusing techniques.
While the invention has been described with reference 1036~
to the embodiments disclosed herein, it is not confined to the specific embodiment set forth, and this application is lntended to cover such operative modifications or changes as may come within the scope of the following claims.
: 10 : 25
sulfides and sulfones such as polydecamethylene sulfide, poly-hexamethylene sulfide, polytetramethyléne'sul~one and the ike;
polyethers such as polybutadiene oxide, polyethylene oxide, polypropylene oxide and the like; polyepihalohydrins such as polyepifluorohydrin; polyenes including cis and trans polydienes such as cis 1, 4 polybutadiene and 1,2 trans polybutadiene;
polyolefins such as poly-l-pe'ntene, poly-l-hexadecene, poly-butene, poly-3-methyl-1-butene and the like; cellulose poly-mers such as cellulose tricaprate; polyacrylates such as poly-isobutyl acrylate; polyacids; polyamides; polyurethanes; and like polymers. Copolymers derived from monomers constituting two or more of the above polymers may also be used. Particul-arly preferred as crystalline segments in the block or graft copolymers are those polymers and copolymers having a TM within the range of about 55C to'about 120C.
~he amorphous segment of the block or graft copolymers may similarly be selected from a wide variety of polymeric ~36~
materials having a TG less than the TM f the crystalline polym~r ~egment with which it is to be associated in the block or gra~t copolymer The TG f the amorphous segment is preferably less the 0C. Examples of suitable amorphous polymers include atactic polymers derived from the same or different monomers or monomer isomers used to form the crystalline or crystallizable segment of the copolymer recited above, said monomers polymer-ized under conditions such that atactic rather than isotactic structure results. Suitable classes of amorphous polymers in-~10 clude polyvinyl ethers; atactic polyolefins: polyacrylates;
polyoxides such as polypropylene oxide; polysulfides; unsymmet-rically branched polyesters and polyamides; aliphatic polyurethanes;
and like materials.
It has been further found that electrostatographic or triboelectric properties of the present toner materials may be optimized and best controlled by employing isomeric copolymers, that is, copolymers wherein the crystalline and amorphous seg-ments have identical chemical compositions but, of course, different chemical structures. Examples of such copolymers would be block or graft copolymers wherein the crystalline segment comprises polybutene-l or -2, and the amorphous segment comprises polyisobutylene; copolymers wherein the crystalline segment is polyhexamethylene sebacate and the amorphous segment is poly-(2-methyl, 2-ethyl, 1,3-propylene sebacate).. Other combinations include isotactic poly tvinyl n-propyl ether) and atactic poly (vinyl isopropyl ether; poly (trimethylene sulfide) and poly (propylene sulfide); poly (hexamethylene oxide) and atactic poly (vinyl butyl ether); isotactic poly (isobutyl acrylate) and atactic poly (n-butyl acrylate). Other isomeric combinations will occur to those skilled in the art.
. .
~64q~ ~
As indicated above, ~or best results the segmented co-polymers should exhibit a Tm within the range of about 45C to a~out 150C and a TG within the range of about 20C to -lOO~C.
In order to avoid the possibility of blocking under extreme conditions, it may be desirable to select crystalline and amor-phous segments such that the copolymers have a Tm in excess of about 55C and a TG of less than 0C.
The block or graft copolymers may be ~abricated into electrostatographic toner using any ~f the known techniques of the prior art by mixing the copolymers with a colorant material.
Mixing may be accomplished by dispersing the colorant in the melted copolymer, hardening the polymer and pulverizing the composition in a device such as a jet or hammermill to form it into small particles. Alternatively, mixing may be carried out by combining the colorant with a solution, dispersion or latex of the copolymer, followed by recovery of the copolymer/colorant mixture in finely divided form by spray drying techniques.
Suitable methods of mixing are more thoroughly described in U.S. Patent 3,502,582. The average particle size of the processed toner should be within the range of about 1 to 30 microns, pre-ferably between about 3 to 15 microns. A subsequent screening or slzing operation may be necessary to produce a toner having this particle size distribution.
The colorant material used in preparing the toner composition may include any pigment or water or organic solvent soluble dye. The most common pigments used in electrostato-graphic toner materials are finely divided carbon black, cyan, magenta and yellow pigments. The most common dyes are the acid, basic and dispersed dyes of suitable color as are known in the art. Typical examples of suitable colorants are discussed in 6~619 U.S. Patent 3,502,582. The pigment or dye should be present in the amount effective to render the toner highly colored so that it will form a clearly visible image on a recording member. Pre-ferably, for sufficient color density, the pigment is employed in an amount from about 1% to about 20% by weight, based on the total weight of the colored toner. If the toner colorant employ-ed is a dye, quantities substantially smaller than about 1% by weight may be used.
q~e toner composition may be formulated into an elec-trostatographic developer composition by combining the finely divided toner with a suitable carrier material such that the toner forms a coating on the carr}er. The toner and carrier material may be premixed or mixed inside the developer region of the xerographic machine. Where the development process in the well known magnetic brush process, the carrier material will be a magnetically attractive material such as finely divided iron particles of about 60 to 120 mesh size. For other than magnetic brush development , the carrier material may be of any of the known particulate substances exhibiting appropriate tri-boelectric effects such that the carrier particles impart a charge to the finer toner whereby the toner adheres to and coats each carrier particle. Examples of suitable carriers are inor-ganic salts, glass, silicon and other materlals such as disclosed in the aforementioned U.S. Patent 3,502,582. The particle size of the carrier should be significantly greater than the toner, preferably within the range of about 50 to 1000 microns. The toner is most effectively employed at a level from about 0.5 to 10 parts by weight per 100 parts by weight of carrier material.
The toner and developer compositions of the present in~ention may also contain any of the additives known to be ~1~36~q~9 included in such compositions such as lubrication aids, anti-oxidants, sensitizing agents, polymeric or non-polymeric plasti-cizers, and the like.
Description of the Preferred Embodiment S The following specific embodiment illustrates the preparation of toner ma-terial wherein the polymeric component comprises an isomeric block copolyester prepared by coupling crystalline poly (hexamethylene sebacate) [poly HMS] and amorphous poly (2-methyl-2-ethyl-1,3,-propylene sebacate) [poly MEPS] using hexamethylene diisocyanate as the coupling agent whereby urethane linkages are formed. The block copolyester was prepared by initially individually synthesizing poly~MS and poly MEPS, and then subjecting a mixture of these homopolymers to a coupling reaction as hereinafter described.
ExamPle 1 Crystalline poly (hexamethylene sebacate) was prepared using a kettle equipped with a stirrer, nitrogen gas inlet tube, thermometer and condenser by reacting sebacic acid with 1,6 hexamethylene glycol in the presence of a p-toluenesulfonic acid catalyst as follows: sebacic acid and hexamethylene glycol were added to the reaction kettle in a respective 1.0 to 1.1 molar ratio along with 0.5 wt % p-toluenesulfonic acid. The 10 mole % excess of glycol was used to ensure the predominant presence of hydroxyl end groups in the reaction product. The mixture was heated to 165C while stirring. At 165C, an amount of xylene was added to assist refluxing and this temperature was main-tained until water evolution ceased (4 hrs.). Afterwards, the condensers were removed and the excess glycol and catalyst were removed by sparging with nitrogen for 0.5 hours at 165C. On cooling to room temperature, the poly (hexamethylene sebacate) ~ 16 -lQ36~0~
crystallized into an off-white solid. ~ext, the poly ~HMS) from above was purified by precipitation from a benzene solution into met~anol using techniques well known in the art. The precipi-tated poly (HMS) was collected by filtration and dried in vacuo.
Analytical data on this purified material indicate an acid number of 1.06, an hydroxyl number of 34.4, an ~n of 3165 g/mole, an MWD (MW/M~) of 1.41 by GPC in chloroform, a glass transition temperature of a~out -62C and a crystalline melting point of about 65C.
Example 2 Amorphous poly (2-methyl-2-ethyl-1,3-propylene sebacate) was prepared by reacting sebacic acid and a 10 mole % excess of 2-methyl-2-ethyl~1,3-propylene glycol in the presence of 0.5 weight % p-toluenesulfonic acid in the same manner as in Example 1. On cooling to room temperature after the polymerization, the poly (MEPS) remained as a clear, tacky fluid. Analysis indicates it has an acid number of 2.40, an hydroxyl number of 19.4, an ~n of 5150 g/mole, an MWD of 1,87 by GPC in chloroform, and a glass transition temperature of about -61C.
Example 3 A block copolyester was prepared by coupling the hydroxy terminated poly (HMS) prepared in Example 1 and the hydroxy terminated poly (MEPS) prepared in Example 2 using hexamethylene diisocyanate as the coupling agent according to the following procedure: three parts by weight of poly (HMS) of Example 1 were mixed with one part by weight of poly (MEPS) of Example 2 in a reaction kettle equipped with a stirrer, nitrogen gas inlet tube, thermometer and condenser. The mixture was heated to 135C with stirring, and hexamethylene diisocyanate 1~364~9 was added at a level of 4.5% by weight of the fluid polymeric mixture. The temperature was maintained at 135C. Within 10 minutes the VisCOslty was such that the polymeric mass began to envelop and climb the stirrer. The coupling reaction was terminated after one hour and the copolymer was dissoIved in benzene and precipitated with stirring into methanol. The precipitate was collected by filtration, washed thoroughly with methanol and dried in vacuo. A yield of about 89% was realized from this coupling reaction. The block copolyester was analyzed by Nuclear Magnetic Resonance to contain 78.6% poly (HMS) and 21.4% poly (MEPS). It had an intrinsic viscosity in chloroform of 0.90 dl/g at 25C, a molecular weight believed to be about 45,000 1 15,000 g/mole, crystalline melting point of about 63C, and a glass transition temperature of about -60C.
Although the structure of the block copolymer molecules produced according to Example 3 is not precisely known, it is believed that because of the predominant presence of segments of polymerized (HMS) in the block copolymer, the copolymer statistically comprises a plurality of repeating crystalline poly HMS segments connected by urethane linkages, said repeating segments in turn connected by urethane linkages with the amor-phous poly (MEPS) segments at various random points along the block copolymer chain, such as illustrated in the following scheme:
.... B-c-B-c-B-c-A-c-B................ wherein B represents polymerized (HMS) A represents polymerized (MEPS) O H H O
and C represents -0-C-N (C H2)6~-C-0-This segment of structure conforms to the generic structure BAB, a species of which generic structure for this copolymer is ' [Bll-c-[Al] c-[Bll], wherein 103640~
Bl is [-(B-c-)2B]
Al is A
,and B 1 is B
Example 4 '~
A xerographic toner material was prepared by forming a mixture of the block copolyester of Exarnple 3 and a finely divided pigment grade carbon black.
A mixture comprising 95 parts by weight of the block copolyester of Example 3, and 5 parts by weight of Molocco H
,, 10 carbon black was formed by heating the copolyester to a temper-ature above its melting point, dispersing therein the carbon black, and mixing until a uniform dispersion of the carbon black in the block copolyester was obtained. The mixture was then guick cooled to a temperature below the melting point of the block copolyester.
Finely divided toner material having an average particle size in the order of about 20 microns was prepared by comminuting the above mixture first in a Fitz mill and subse-~uently in a jet pulverizer.
The toner was tested by employing it as the toner in a "Xerox 3600" copy machine embodying a contact heat fusing de-vice and found to produce very satisfactory copies without toner offset on the fusing roll.
Exam~les 5 - 11 Several additional samples of isomeric block copoly-esters having various ratios of poly (HMS) and poly (MEPS) were prepared ~y coupling the poly (HMS) of Example 1 and the pol,y (MEPS) of Example 2 using various coupling agents. Synthesis data for these copolyesters is shown in Table 1.
The block copolyesters of Examples 5, 7, 9~ 10 and 11 : !~ ~l)3f~9 .
o C~ U C~
U o o o o o o o o o oo r~ In In ~
_ ~ ~ n E~
OD ~ ~ ~D a) o ~q ~ ~ ~ o r~ o o~ o~
. ~ o U~ U~
o ~C~ .
~: .
~ o o o o ~ ~
_I ,~ o ~ ~I r- o ~r .~
c~ ~ N t`l I
O O V O ~`1 0 , ~C ~ ~ rl Z O ~ ~
~ u ~--H
. I ~ ~ ~ ~ ~ ~
I~ ~`l ~ ~ ~ ~ d' ~ ' V U U U C~ ~ U
I -- O ~ ~ ~ U ~
,~ 1 U
m E~ ..
., .,, "., ,,, , u~ a~
. ~ o ~ ~ ~ ~ ~ In ~:
u~ ~D ~ ~ O O
n O ~
. Q
~ O CO CO OD ~.
o ~ ~ ~ ~ ~ ~
p~ ~ ~
ol :
.
`
l x x x x x x x u~ ~ ~ ~ ~ ~ F~ ~1 ~ ~i ~q~36~ f were prepared by the method of Example 3; with regard to the block copolyesters of Examples 6 and 8, the procedure of Example 3 was modified somewhat in that refluxing was carried out in chlorobenzene (132C) containing a small amount of pyridine. General techniques for preparing linear copolyesters using coupling agents are known in the art as, for example, disclosed in U.S. Patent 2,691,006.
The copolymers of Examples 5 - 11 were each processed into toner material by the method of Example ~ and each per-formed satisfactorily when used in a xerographic machine.
As indicated above, toner materials based on the seg-mented copolymers of the present invention exhibit minimal latent heats of fusion and at the same time the sharp, well defined melting points desirable in a toner material. This ; 15 may be illustrated by a comparison of the latent heats of fusion PHU - in calories/gm.) and melting points (Tm) for a plurality of polymer samples containing polymerized hexamethy-lene sebacate (E~S) and polymerized 2 methyl-2-ethyl-1,3-propylene sebacate ~MEPS).
Example 12 A series of homopolymer blends having various weight ratios between about 20-80% oE poly (HMS) and poly (MEPS) were prepared by forming intimate admixtures of the poly (HMS) pre-pared according to Example 1 and the poly (MEPS) prepared according to Example 2.
A series of block copolymer samples having various weight ratios between about 20-80% of poly (HMS) and poly (MEPS) were prepared according to the process of Example 3.
A series of random copolymers also having various weight ratios between about 20-80% of polymerized HMS and poly-merized MEPS were prepared by a process similar to that described in Example 1 by reacting simultaneously a mixture of 1, 6 hexamethylene glycol, 2-methyl-2-ethyl-1,3 propylene glycol and sebacic acidO Various copolymer compositions were achieved by alterning, systematically, the molar ratio of the two diols in the condensation reaction with sebacic acid. The copolymers so prepared exhibited Mn values within the range of about 2200 to 3600 g/mole.
Samples of each type of polymer composition for various levels of polymerized HMS content were evaluated for latent heat of fusion and crystalline melting point data, the results plotted, and the plots interpolated at 80%, 60%, 40%, and 20%
HMS content. Results are shown in Table 2.
% Random Homopolymer Block HMS CopolYmer Blend ~polymer Tm ~ Hu Tm d H T~ ~Hu 100% 65C 30 65C 30 65C 30 80% 57C ~10 64C 25 63C 17 60% 42C - 62C 18 61C 11 40% 22C - 62C 12 56C 7 20% 0C - 61C 6 5~C 6 As can be seen from Table 2, the melting point of the random copolymers drops off rapidly as the % HMS in the random copolymer is decreased with a corresponding increase in % MEPS. 5 Below about 60% ~S, the copolymers are a viscous fluid unsuit-able for use in a toner composition. With the homopolymer blends, the lowering of Tm is much less severe, but~ Hu is found to drop off in almost direct proportion to the amount of poly (HMS) in the blend. With the block copolymers, the lower-~3~ 9 ing of Tm is somewhat greater than in the blend, but still quite acceptable for toner use, but most significantly the drop in u is much higher than in comparable samples of the blend.
Thus, considerably less heat energy is required to melt or fuse toner based on the block copolymers than is required to melt toner based on the homopolymer blend.
~lthough the toner ~omposition of the present lnven-tion may be used in electrophotographic processes embodying any of the well known techniques of image fixation or fusing such as radiation, vapor, or liquid fusing, it is employed most advan-tageously in processes involving contact fusing, as discussed above, or flash fusing such as for example disclosed in U.S.
Patents 3,465,203, 3,474,223, and 3,529,129. In each of these processes, exposure of the image recording medium bearing the powdered toner image, usually paper, to a source of hea~ is for an extremely llmited tlme duration. In contact fusing, a moving recording medium is exposed to heat while the medium passes through a nlp formed by a heated pressure roller and a second support roller. Wlth radiant flash fusing, the recording medium is exposed to heat energy in the form of electromagnetic waves generated usually by a gas lamp, such as a xenon lamp, for a period of timed measured in milliseconds. With each of these processes, a maximum amount of heat energy sufficient to properly fuse the toner without scortching the recording medium is re-quired over a short period of time. It is thus evident that the toner compositions of the present invention having sharp well defined melting points and controllably minimal latent heats of fusion respond particularly well for use in processes involving such fusing techniques.
While the invention has been described with reference 1036~
to the embodiments disclosed herein, it is not confined to the specific embodiment set forth, and this application is lntended to cover such operative modifications or changes as may come within the scope of the following claims.
: 10 : 25
Claims (24)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A finely divided particulate, electrostato-graphic toner composition comprising a uniform mixture of:
a) a colorant material and b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20°C and a melting point of at least about 45°C, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
a) a colorant material and b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20°C and a melting point of at least about 45°C, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
2. The toner composition of Claim 1 wherein said polymeric material has an average molecular weight within the range of about 5,000 to 200,000 grams per mole and melting point within the range of about 45°C to about 150°C.
3. The toner composition of Claim 2 wherein said polymeric material is a block copolymer having a formula selected from the group consisting of: [BA]n, [AB]n, [BAB]n, and [ABA]n, wherein A represents the amorphous polymeric seg-ment, B represents the crystalline or crystallizable polymer-ic segment, and n is a whole number equal to 1 or greater.
4. The toner composition of Claim 3 wherein the average molecular weight of said A or B polymeric segments is within the range of about 1,000 to 20,000 grams per mole.
5. A toner composition which is the reaction product of at least two preformed polymers, one of said pre-formed polymers being crystalline or crystallizable and having a glass transition temperature within the range of about 20°C. to -100°C. and a melting point within the range of about 45°C. to 150°C., and another of said preformed polymers being amorphous and having a glass transition temperature of less than 45°C.
6. The toner composition of Claim 5 wherein said segmented copolymer is a block copolyester having one or more repeating units of crystalline polyester chemically linked to one or more repeating units of amorphous polyester.
7. The toner composition of Claim 6 wherein the crystalline segment of said block copolymer comprises poly (hexamethylene sebacate) and the amorphous segment of said block copolymer comprises poly (2-methyl-2-ethyl-1,3-propylene sebacate).
8. The toner composition of Claim 1 wherein said colorant material is present at a level of from about 1% to about 20% by weight of said composition.
9. The toner composition of Claim 8 wherein the average particle size of the toner particles is within the range of about 1 to 30 microns.
10. An electrostatographic developer composition comprising from about 0.5 to 10% by weight of the toner particles of Claim 8 and about 90 to about 99.5% by weight of carrier particles, said carrier particles having an average particle size greater than the toner particles whereby the toner particles adhere to and coat each carrier particle.
11. In an electrophotographic imaging process including the steps wherein a particulate electrostatographic toner composition is applied in image configuration to the surface of a recording member, and said recording member bearing said toner composition in image configuration is subjected to heat or heat and pressure sufficient to fuse said toner composition to the surface of said recording mem-ber, the improvement which comprises conducting said imaging process using a finely divided toner composition comprising a uniform mixture of:
a) a colorant material and b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20°C and a melting point of at least about 45°C, said at least one amorphous polymeric segment individ-ually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
a) a colorant material and b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20°C and a melting point of at least about 45°C, said at least one amorphous polymeric segment individ-ually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
12. The process of Claim 11 wherein said polymeric material has an average molecular weight within the range of about 5,000 to 200,000 grams per mole and a melting point within the range of about 45°C to about 150°C.
13. The process of Claim 12 wherein said polymeric material is a block copolymer having a formula selected from the group consisting of: [BA]n, [AB]n, [BAB]n, and [ABA]n, wherein A represents the amorphous polymeric segment, B
represents the crystalline or crystallizable polymeric seg-ment, and n is a whole number equal to 1 or greater.
represents the crystalline or crystallizable polymeric seg-ment, and n is a whole number equal to 1 or greater.
14. The process of Claim 13 wherein the average molecular weight of said A or B polymeric segments is within the range of about 1,000 to 20,000 grams per mole.
15. The process of Claim 12 wherein said segment-ed copolymer is the reaction product of at least two pre-formed polymers, one of said preformed polymers being crystalline or crystallizable and having a glass transition temperature within the range of about 20°C. to -100°C. and a melting point within the range of about 45°C. to 150°C., and another of said preformed polymers being amorphous and having a glass transition temperature of less than 45°C.
16. An electrophotographic imaging process compris-in the steps of subjecting the surface of a charged photo-conductive insulating layer to a pattern of light and shadow such that an electrostatic latent image is formed on the surface of said layer, developing said latent image by contact of said surface with a developed composition compris-ing a mixture of carrier particles and toner material, transferring the toner material in image configuration from said surface to the surface of a recording member, and heating the surface of said recording member sufficient to fuse said toner composition to the surface of said recording member, said toner material comprising a finely divided composition comprising a uniform mixture of:
a) a colorant material and b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20°C, a melting point of at least about 45°C, and an average molecular weight within the range of about 5,000 to 200,000 grams per mole, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
a) a colorant material and b) a polymeric material, said polymeric material comprising a segmented copolymer consisting of at least one crystalline or crystallizable polymeric segment chemically linked to at least one amorphous polymeric segment, said segmented copolymer having a glass transition temperature of less than about 20°C, a melting point of at least about 45°C, and an average molecular weight within the range of about 5,000 to 200,000 grams per mole, said at least one amorphous polymeric segment individually having a glass transition temperature less than the melting point of said crystalline or crystallizable polymeric segment.
17. The process of Claim 16 wherein said polymeric material is a block copolymer having a formula selected from the group consisting of: [BA]n, [AB]n, [BAB]n, and [ABA]n, wherein A represents the amorphous polymeric segment, B
represents the crystalline or crystallizable polymeric seg-ment, n is a whole number equal to 1 or greater, and where-in the average molecular weight of each A or B polymeric segments is within the range of about 1,000 to 20,000 grams per mole.
represents the crystalline or crystallizable polymeric seg-ment, n is a whole number equal to 1 or greater, and where-in the average molecular weight of each A or B polymeric segments is within the range of about 1,000 to 20,000 grams per mole.
18. The process of Claim 16 wherein said segment-ed copolymer is the reaction product of at least two pre-formed polymers, one of said preformed polymers being crystalline or crystallizable and having a glass transition temperature within the range of about 20°C. to -100°C. and a melting point within the range of about 45°C. to about 150 C., and another of said preformed polymers being amorphous and having a glass transition temperature of less than 45°C.
19. The process of Claim 18 wherein said segmented copolymer is a block copolyester having one or more repeating units of crystalline polyester chemically linked to one or more repeating units of amorphous polyester.
20. The process of Claim 16 wherein said colorant material is present at a level of from about 1% to about 20% by weight of said composition.
21. The process of Claim 20 wherein the average particle size of the toner particles is within the range of about 1 to 30 microns.
22. The process of Claim 21 wherein the developed compo-sition comprises from about 0.5 to 10% by weight of toner particles and about 90 to about 99.5% by weight of carrier par-ticles, said carrier particles having an average particle size greater than the toner particles whereby the toner particles adhere to and coat each carrier particle.
23. The process of Claim 16 wherein said heating is carried out by passing the recording member through a zone of heat and pressure.
24. The process of Claim 16 wherein said heating is carrier out by exposing the developed surface of the recording member to electromagnetic radiation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US41862873A | 1973-11-23 | 1973-11-23 | |
| US41865073A | 1973-11-23 | 1973-11-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1036409A true CA1036409A (en) | 1978-08-15 |
Family
ID=27024210
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA208,944A Expired CA1036409A (en) | 1973-11-23 | 1974-09-11 | Electrostatographic toner composition |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5087032A (en) |
| CA (1) | CA1036409A (en) |
| DE (1) | DE2440348A1 (en) |
| FR (1) | FR2252595B1 (en) |
| GB (1) | GB1478417A (en) |
| NL (1) | NL7414692A (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5665146A (en) * | 1979-10-31 | 1981-06-02 | Toyobo Co Ltd | Electrophotographic toner |
| JPS578549A (en) * | 1980-06-20 | 1982-01-16 | Fuji Xerox Co Ltd | Dry toner |
| EP0099140B1 (en) * | 1982-06-17 | 1987-08-26 | Océ-Nederland B.V. | A toner powder and a method of forming fixed images by means of this toner powder |
| WO1986005602A1 (en) * | 1985-03-15 | 1986-09-25 | Konishiroku Photo Industry Co., Ltd. | Toner for electrostatic image developement and process for forming image by using it |
| JPH083660B2 (en) * | 1986-06-19 | 1996-01-17 | コニカ株式会社 | Toner for developing electrostatic image and image forming method using the same |
| JPH0785179B2 (en) * | 1986-07-22 | 1995-09-13 | コニカ株式会社 | Toner for electrostatic image development |
| JPS6366563A (en) * | 1986-09-09 | 1988-03-25 | Toyo Ink Mfg Co Ltd | powder toner |
| US4847175A (en) * | 1987-12-02 | 1989-07-11 | Eastman Kodak Company | Electrophotographic element having low surface adhesion |
| JPH07744B2 (en) * | 1988-08-01 | 1995-01-11 | 三菱重工業株式会社 | Polymer elastomer composition |
| JP3491883B2 (en) | 1999-09-28 | 2004-01-26 | 花王株式会社 | Binder resin for toner |
| US7763409B2 (en) * | 2004-05-19 | 2010-07-27 | Mitsui Chemicals, Inc. | Binder resin for toner, method for production thereof, and toner |
| JP5742007B2 (en) * | 2011-03-08 | 2015-07-01 | 株式会社リコー | Resin for toner, toner and developer containing the resin for toner, and image forming apparatus, image forming method, and process cartridge using the developer |
| JP5954218B2 (en) * | 2013-02-25 | 2016-07-20 | 富士ゼロックス株式会社 | Electrostatic image developing toner, electrostatic image developer, toner cartridge, developer cartridge, process cartridge, image forming apparatus, and image forming method |
-
1974
- 1974-08-22 DE DE19742440348 patent/DE2440348A1/en active Pending
- 1974-09-11 CA CA208,944A patent/CA1036409A/en not_active Expired
- 1974-11-11 NL NL7414692A patent/NL7414692A/en not_active Application Discontinuation
- 1974-11-12 GB GB4900374A patent/GB1478417A/en not_active Expired
- 1974-11-18 JP JP49132621A patent/JPS5087032A/ja active Pending
- 1974-11-22 FR FR7438505A patent/FR2252595B1/fr not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2252595A1 (en) | 1975-06-20 |
| FR2252595B1 (en) | 1978-11-24 |
| JPS5087032A (en) | 1975-07-12 |
| NL7414692A (en) | 1975-01-31 |
| GB1478417A (en) | 1977-06-29 |
| DE2440348A1 (en) | 1975-05-28 |
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