JP3454270B2 - Non-magnetic one-component full-color developing toner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner in a non-magnetic one-component developing method used in fields such as electrophotography.

[0002]

BACKGROUND OF THE INVENTION Electrophotography is described in US Pat. No. 2,297,691.
Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-43
As disclosed in various publications such as Japanese Patent No. 24748, generally, an electrostatic latent electrostatic latent image is formed on a photoreceptor containing a photoconductive substance by various means, and then the latent image is developed as a powder image with a toner. If necessary, the powder image is transferred to paper or the like and then fixed by heating, pressurizing, solvent vapor or the like.

Further, in recent years, an electrostatic latent image of an original is formed by exposing it to light that has been spectrally dispersed, and is developed with color toner of each color to obtain a colored copy image, or the copy images of each color are superposed. A color copying method for obtaining a full-color copied image has been put into practical use, and yellow, magenta, cyan, and other color toners in which dyes and / or pigments of respective colors are dispersed in a binder resin are manufactured as color toners used for the method. ing.

As a toner developing method, a non-magnetic one-component developing method has recently been adopted in order to downsize the apparatus, simplify maintenance, and cope with colorization.
As the non-magnetic one-component developing method, a contact developing method such as a touch-down method and a flying developing method such as a projection method are known. In any case, non-magnetic toner is coated on a developing sleeve by a coating member such as an elastic blade. The point is to apply a thin layer uniformly.

[0005]

However, in the non-magnetic one-component developing method, in general, the method of imparting chargeability to the toner is
As described above, it is unavoidable that the thinned toner comes into contact with the developing sleeve or the elastic blade, so that the mechanical stress on the toner is extremely large,
In particular, the frictional heat generated during continuous use often causes the toner to aggregate or solidify. Ultimately, such a phenomenon causes fusion of the toner aggregates to the developing sleeve and the elastic blade, and appears as a fatal image defect.

In order to solve this problem, a method has been proposed in which an external additive such as fine particle silica is sprinkled on the surface of the toner particles to make the toner particles non-adhesive and to improve the aggregation of the particles. However, in this method, since the external additive fine particles may fall off from the toner surface or fly off, or be embedded in the toner particles due to long-term stirring in the developing device, the initial characteristics cannot be maintained, and thus durability is improved. It was insufficient in terms of sex. After all, it is considered that the above-mentioned problems need to be improved mainly in terms of the characteristics of the binder resin for the toner in the non-magnetic one-component toner, and a drastic solution has been desired in the past.

Further, in the case of a color toner, it is necessary for the resin to satisfy the above-mentioned problems as a resin and to satisfy various requirements such as image glossiness and transparency.
The present invention has been made to solve the problems in view of the above-mentioned current situation, and the purpose thereof is to have the following performances, and as a result, a non-magnetic one having excellent stability and durability over time. An object of the present invention is to provide an image forming method using a component developing method.

Aggregation of toner is unlikely to occur. Less fusion to photoconductor, developing sleeve, elastic blade, etc. Good fluidity and high toner transportability. Even under a high temperature and high humidity environment, toner aggregation / fusion does not easily occur. The offset phenomenon does not occur during fixing and the fixing strength is high. Excellent in gloss and transparency as a color toner. Image quality does not change even after continuous use or long-term use.

[0009]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that a polyester resin having specific thermal characteristics is used as a binder resin in an image forming method using a non-magnetic one-component developing system. It has been found that the above object can be satisfied by using a toner of the present invention and arranging a fine particle additive on the surface thereof, and reached the present invention. That is, the gist of the present invention is a non-magnetic one-component full-color toner that develops a latent image by supplying a thinned toner in contact with a latent image carrier, and the toner is at least a colorant, colorless or colorless. It contains a light-colored charge control agent and a polyester resin, and the monomer constituting the polyester resin is composed of a polyhydric alcohol and a polybasic acid and has a glass transition temperature (T
g) is a variable on the x-axis and the softening point (Sp) is a variable on the y-axis, and plotted on the xy coordinates, the physical properties are within the range enclosed by the straight lines represented by the following formulas, Furthermore, the present invention resides in a non-magnetic one-component full-color developing toner characterized in that the surface of the toner particles contains at least one kind of fine particle additive.

Formula Sp = 4Tg-110 Formula Sp = 4Tg-170 Formula Sp = 90 Formula Sp = 120 Hereinafter, the present invention will be described in detail. The non-magnetic toner used in the present invention contains a colorant, a charge control agent, a polyester resin and the like as constituent components.

As the colorant contained in the non-magnetic toner according to the present invention, any suitable pigment or dye is used. For example, carbon black, lamp black, iron black, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dyes and pigments, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dyes,
Any conventionally known dyes and pigments such as anthraquinone dyes, monoazo and disazo dyes and pigments may be used alone or in combination. Binder resin 10
It is preferably used in an amount of 0.5 to 20 parts by weight, more preferably 2 to 10 parts by weight, based on 0 parts by weight.

As the charge control agent, all known charge control agents can be used. For example, for positive charging, amino group-containing vinyl copolymer, quaternary ammonium salt compound,
There are polyamine resins, etc., chromium for negative charging,
Known are salts of salicylic acid or alkylsalicylic acid containing a metal such as zinc, iron, cobalt or aluminum with the above-mentioned metal, a metal complex and the like. The amount used is preferably 0.1 to 25 parts by weight, more preferably 1 to 15 parts by weight, based on 100 parts by weight of the resin. in this case,
The charge control agent may be added to the resin, or may be used by being attached to the surface of the toner particles.

Among these charge control agents, in consideration of the charge imparting ability to the toner and the color toner adaptability (the charge control agent itself is colorless or light-colored and does not hinder the color tone of the toner), the charge control agent is used for positive chargeability. Is preferably an amino group-containing vinyl-based copolymer and / or a quaternary ammonium salt compound. For negative charging, a metal salt or metal complex of salicylic acid or alkylsalicylic acid such as chromium, zinc or aluminum is preferable.

Of these, examples of the amino group-containing vinyl copolymer include copolymer resins of amino acrylates such as N, N-dimethylaminomethyl acrylate and N, N-diethylaminomethyl acrylate, and styrene and methyl methacrylate. Can be mentioned. Examples of the quaternary ammonium salt compound include tetraethylammonium chloride, a salt-forming compound of benzyltributylammonium chloride and naphtholsulfonic acid, and the like. For positively chargeable toners, the amino group-containing vinyl copolymer and the quaternary ammonium salt compound may be added alone or in combination.

As the metal salt or metal complex of salicylic acid or alkylsalicylic acid, chromium or zinc complex of 3,5-ditertiarybutylsalicylic acid is particularly preferable among various known substances. Further, in order to improve the dispersibility and compatibility in the toner, the above colorants and charge control agents may be pre-dispersed by so-called kneading with a resin, so-called masterbatch treatment.

On the other hand, the polyester resin used in the present invention comprises a polyhydric alcohol and a polybasic acid, and if necessary, at least one of the polyhydric alcohol and the polybasic acid is a polyfunctional component having a valence of 3 or more (crosslinking). It is obtained by polymerizing a monomer composition containing (component). In the above, as the dihydric alcohol used for the synthesis of the polyester resin, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
1,4-butanediol, neopentyl glycol,
1,4-butenediol, 1,5-pentanediol,
Examples thereof include diols such as 1,6-hexanediol, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, bisphenol A alkylene oxide adducts such as polyoxypropyleneized bisphenol A, and the like. Among these monomers, it is particularly preferable to use a bisphenol A alkylene oxide adduct as the main component monomer, and among them, the average number of alkylene oxide additions per molecule is 2 to 2.
The adduct of 7 is preferred.

Examples of the trihydric or higher polyhydric alcohol involved in the crosslinking of the polyester include sorbitol,
1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol , 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, and the like.

On the other hand, examples of the polybasic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid and azelaic acid. Examples thereof include acids, malonic acids, anhydrides of these acids, lower alkyl esters, alkenylsuccinic acids or alkylsuccinic acids such as n-dodecenylsuccinic acid and n-dodecylsuccinic acid, and other divalent organic acids.

Examples of tribasic or higher polybasic acids involved in the crosslinking of polyester include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid,
1,2,4-cyclohexanetricarboxylic acid, 2,5,
7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octane tetracarboxylic acid, these anhydrides, etc. can be mentioned.

These polyester resins can be synthesized by a usual method. Specifically, the reaction temperature (1
Conditions such as 70 to 250 ° C.) and reaction pressure (5 mmHg to normal pressure) are determined according to the reactivity of the monomer, and the reaction may be terminated when predetermined physical properties are obtained. As described above, the softening point (S
Those having p) and a glass transition temperature (Tg) within the ranges represented by the above formulas (1) to (4) were used, which are specifically shown in FIG. As is clear from FIG. 1, the Sp of the polyester resin according to the present invention is 90 to 120 ° C.
The range of Tg is, for example, 50 to 50 when the softening point is 90 ° C.
The temperature is 65 ° C, and is 60 to 75 ° C when the softening point is 130 ° C. In this case, when Sp is lower than the above range, an offset phenomenon at the time of fixing tends to occur, and when Sp is higher than the range, fixing energy increases, and the gloss and transparency of color toner tend to deteriorate, which is not preferable. . Also, T
When g is lower than the above range, toner agglomerates and sticking are likely to occur, and when it is higher than the above range, the fixing strength at the time of heat fixing tends to decrease, which is not preferable. Sp can be adjusted mainly by the molecular weight of the resin, and the number average molecular weight is preferably 2000 to 20000, more preferably 3000 to 1
It is good to set it to 2000. Further, Tg can be adjusted mainly by selecting a monomer component constituting the resin, and specifically, Tg can be increased by using an aromatic polybasic acid as an acid component as a main component. That is, among the above-mentioned polybasic acids, phthalic acid, isophthalic acid, terephthalic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, etc., and their anhydrides, lower alkyl esters, etc. It is desirable to use it as the main component.

Sp of polyester resin is JIS K72
10 and the flow tester described in K6719. Specifically, as shown in FIG. 2, while using a flow tester (CFT-500, manufactured by Shimadzu Corporation) to heat about 1 g of the sample 3 at a heating rate of 3 ° C./min, an area of 1 cm ² 30kg with Plunger 1 of
A load of / cm ² is applied, and the die 4 having a hole diameter of 1 mm and a length of 10 mm is extruded. As a result, a plunger stroke-temperature curve as shown in FIG. 3 is drawn, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 is the softening point.

The Tg is measured by a differential scanning calorimeter (DS).
C). On the other hand, in general, when the acid value of the polyester resin is too high, it is difficult to obtain a stable high charge amount, and the charge stability at high temperature and high humidity tends to be deteriorated. Therefore, in the present invention, the acid value is 50 KOH.
It is preferable that the amount is not more than mg / g, more preferably 30 KO.
It is preferable to adjust it so that it is Hmg / g or less. As a method for adjusting the acid value within the above range, other than the method of controlling the addition ratio of the alcohol-based and acid-based monomers used during resin synthesis, for example, the acid monomer component is previously converted into a lower alkyl ester by a transesterification method. Examples of the known method include, but are not limited to, a method of synthesizing a residual acid group by adding a basic component such as an amino group-containing glycol to the composition, and a method of synthesizing the residual acid group. Needless to say, can be adopted. The acid value of the polyester resin is JIS K00.
It is measured according to the method of 70. However, if the resin is difficult to dissolve in the solvent, a good solvent such as dioxane may be used.

Further, as the resin of the toner according to the present invention, it is also possible to mix and use other known resins within a range not impairing the performance of the present invention. Examples thereof include polyester resins other than the present invention, styrene acrylic resins, epoxy resins, butyral resins, styrene butadiene resins and the like. The non-magnetic toner according to the present invention contains at least one kind of fine particle additive on the surface of its particles. These are mainly intended to improve the tackiness, cohesiveness, fluidity, etc. of the toner particles, and at the same time, improve the triboelectric chargeability and durability of the toner. Specific examples thereof include organic and inorganic fine particles having an average primary particle diameter of 0.001 to 5 μm, and particularly preferably 0.002 to 3 μm, the surface of which may be treated. For example, polyvinylidene fluoride or polytetrafluoroethylene. Fluorine resin powders such as, zinc stearate, fatty acid metal salts such as calcium stearate, resin beads whose main component is polymethylmethacrylate or silicone resin, minerals such as talc and hydrotalcite, silicon oxide, aluminum oxide , Metal oxides such as titanium oxide, zinc oxide, and tin oxide.

Of these, silicon oxide fine particles are more preferable, and silicon oxide fine particles whose surface is subjected to a hydrophobic treatment are particularly preferable. As a method of hydrophobizing, for example, a method of reacting or physically adsorbing silicon oxide fine particles with an organic silicon compound such as hexamethyldisilazane, trimethylsilane, dimethyldichlorosilane and the like, and chemically treating it can be mentioned. The addition ratio of these fine particle additives to the non-magnetic toner is preferably 100: 0.01 to 10 by weight, and more preferably 100: 0.05 to 5.

In the non-magnetic toner according to the present invention,
As the other constituent component, any known substance such as a release agent such as low molecular weight polyethylene or polypropylene can be contained. The average particle size of the toner is preferably 3 to 20 μm, more preferably 5 to 20 μm.
15 μm is more preferable.

The non-magnetic toner according to the present invention can be manufactured by various manufacturing methods including conventionally known methods, and the following examples are mentioned as general manufacturing methods. The resin, the charge control substance, the colorant, and the additives that are added as necessary are uniformly dispersed with a Henschel mixer or the like. The dispersion is melt-kneaded with a kneader, an extruder, a roll mill or the like. The kneaded product is roughly crushed with a hammer mill, a cutter mill, or the like, and then finely crushed with a jet mill, an I-type mill, or the like. The finely pulverized product is classified by a dispersion classifier, a zigzag classifier, or the like. Depending on the case, silica or the like is dispersed in the classified product with a Henschel mixer or the like.

Further, as a method completely different from the above-mentioned manufacturing method, for example, there may be mentioned a manufacturing method by a suspension polymerization method. As described above, the non-magnetic toner according to the present invention uses, as the resin, a polyester resin having a softening point and a glass transition temperature in a specific range, in other words, a high glass transition temperature even at a low softening point, and the toner particle surface is By containing the fine particle additive, the strength against mechanical stress can be increased, the cohesiveness and the fusing property of the toner can be suppressed, and the durability can be improved.

The toner of the present invention is useful for image formation by a non-magnetic one-component developing system in electrophotography. An image forming method using the toner of the present invention will be described below. Such an image forming method is based on a non-magnetic one-component developing method in electrophotography, in which a thinned toner is supplied to a latent image carrier to develop the latent image. Incidentally, the thinning of the toner is usually provided with a toner conveying member, a toner layer thickness regulating member and a toner replenishing auxiliary member, and the replenishing auxiliary member, the toner conveying member and the toner layer thickness regulating member and the toner conveying member are respectively provided. This is done using the abutting device.

The image forming method of the present invention will be described in more detail with reference to the drawings. FIG. 4 is an explanatory diagram showing an example of a developing device using a non-magnetic one-component toner that can be used for carrying out the image forming method of the present invention. In the drawing,
Toner 1 of the present invention built in the toner hopper 12
1 is forcibly moved to the sponge roller (toner replenishing auxiliary member) 9 by the stirring blade 10, and the toner is supplied to the sponge roller 9. And sponge roller 9
The toner taken in is carried to the toner carrying member 7 by the sponge roller 9 rotating in the direction of the arrow,
The toner conveying member 7 is rubbed and electrostatically or physically adsorbed, the toner conveying member 7 strongly rotates in the direction of the arrow, and a uniform thin toner layer is formed by a steel elastic blade (toner layer thickness regulating member) 8 and friction occurs. Get charged. After that, the toner is conveyed to the surface of the electrostatic latent image carrier 6 which is in contact with the toner conveying member 7, and the latent image is developed. The electrostatic latent image is obtained, for example, by exposing the organic photoconductor to a DC charge of 500 V and then exposing it.

[0030]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, in each of the examples and comparative examples, simply "part" means "part by weight". Production of Polyester Resins 1 to 4 The materials having the compositions shown in Table 1 were placed in a glass 3-liter four-necked flask, equipped with a thermometer, a stainless steel stirring rod, a downflow condenser and a nitrogen inlet tube, and in an electric heating mantle heater. In a nitrogen stream at 200 ℃ normal pressure in the first half, 2 in the second half
The reaction proceeded with stirring at 20 ° C. under reduced pressure. The reaction state was traced while measuring the softening point, the reaction was stopped when the predetermined physical properties were reached, and then cooled to room temperature to obtain each polyester resin.

[0031]

[Table 1]

In Table 1, alcohol and acid components are represented by abbreviations and symbols, but they represent the following raw material names. Diol A: Polyoxypropylene (2.2)-
2,2-bis (4-hydroxyphenyl) propanediol B: polyoxyethylene (2.2)-
2,2-bis (4-hydroxyphenyl) propane EG: ethylene glycol TPA: terephthalic acid IDSA: isododecenyl succinic acid TMAA: trimellitic anhydride Table 2 shows the physical property values of the above polyester resins.

[0033]

[Table 2]

Production of Comparative Polyester Resins 5 to 8 The reaction was carried out in exactly the same manner as the production method of the above polyester resin except that the composition materials shown in Table 3 below were used. The reaction was allowed to proceed while measuring the softening point, the reaction was stopped when the predetermined physical properties were reached, and then the mixture was cooled to room temperature to obtain each polyester resin.

[0035]

[Table 3]

In Table 3, alcohol and acid components are represented by abbreviations and symbols, which have the same meanings as in Table 1 except for the following. Diol C: Hydrogenated bisphenol A FA: Fumaric acid Table 4 shows the physical property values of these polyester resins.

[0037]

[Table 4]

Examples 1 to 7 and Comparative Examples 1 to 4 Table 5 shows a list of toner compositions of Examples 1 to 7 and Comparative Examples 1 to 4.

[0039]

[Table 5]

The method for producing the toner was as follows. Melt and knead each toner material with a kneader,
After cooling, coarse pulverization was performed using a hammer mill, and then fine pulverization was performed using an air jet type fine pulverizer. The obtained fine powder was classified to select a particle size of 5 to 20 μm to obtain a toner. The volume average particle diameters measured by a Coulter counter were all within the range of 10 ± 0.5 μm.
To 100 parts of these toners, 0.5 part of fine particle silica (Aerosil R-972, manufactured by Nippon Aerosil Co., Ltd.) was externally added with a Henschel mixer.

These toners were evaluated by an actual copying test using the developing device shown in FIG. In the case of positively chargeable toner as the photoconductor (Example 1 and Comparative Example 1)
Is a selenium drum, and a negatively chargeable toner is used (Examples 2 to 2).
7 and Comparative Examples 2 to 4) each used an organic photoconductor and were developed by a reversal development method. In this case, in order to confirm the durability of the toner, a running test was performed on about 20,000 sheets, and the state of aggregation and fusion of the toner was observed with a microscope.
The change in image density was measured using a reflection densitometer, and the change in image quality was visually observed. The fixing is performed while supplying oil using a silicon roller, the fixing speed is 120 mm / sec and the fixing temperature is 180 ° C. Regarding the fixing strength of the toner, the solid portion of the copy after fixing is folded in two and the toner is adhered. The state was observed and the fixability was evaluated.

The evaluation results are summarized in Table 6. According to this, the image forming method using the non-magnetic one-component toner of the present invention can obtain a high-quality and stable image, and since the toner is not aggregated or fused, the durability as a toner is also improved. Excel. Further, the fixing property of the toner is also good. On the other hand, according to the comparative example, the durability is poor such that the poor image quality due to the fusion of the toner to the developing sleeve or the elastic blade is remarkable, and there is a problem in the fixing strength.

[0043]

[Table 6]

[0044]

The effects obtained by the present invention are as follows. With the non-magnetic one-component toner of the present invention, (1) initial characteristics are maintained even when used continuously for a long period of time, toner aggregation and change in chargeability do not occur, and toner filming does not occur. Also, the fixing property is good. (2) A high-quality copy that is not affected by environmental changes such as aging and high temperature and high humidity can be obtained. (3) A color toner having excellent transparency and fastness and having good hue and saturation can be obtained, and can be applied to a color electrophotographic method. As described above, according to the present invention, a stable and high-quality image can be easily obtained. Therefore, the present invention is industrially very useful.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a softening point of a polyester resin according to the present invention and an effective range of a glass transfer temperature.

FIG. 2 is a schematic sectional view showing a central portion of a flow tester.

FIG. 3 is a plunger stroke (displacement) -temperature curve of a flow tester.

FIG. 4 is a schematic explanatory view showing an example of a developing device useful for carrying out the method of the present invention using the toner of the present invention.

[Explanation of symbols]

1 Plunger 2 cylinders 3 samples 4 die 5 die press 6 Electrostatic latent image carrier 7 Toner transport member 8 Elastic blade (toner layer thickness control member) 9 Sponge roller (toner supply auxiliary member) 10 stirring blades 11 toner 12 toner hopper

Front page continuation (72) Inventor Hirofumi Oda 370 Enzo, Chigasaki City, Kanagawa Mitsubishi Kasei Co., Ltd. Chigasaki Plant (56) References JP-A-1-259370 (JP, A) JP-A-2-82 (JP) , A) JP-A-2-66564 (JP, A) JP-A-2-269364 (JP, A) JP-A-3-2779 (JP, A) JP-A-4-40470 (JP, A) JP-A 62-45622 (JP, A) JP-A-63-2074 (JP, A) JP-B 3-15180 (JP, B2) JP-B 3-63065 (JP, B2) JP-B 4-492 (JP, A) B2) Japanese Patent Publication Sho 61-59333 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (3)

(57) [Claims] 1. A non-magnetic one-component full-color developing toner for developing a latent image by supplying a thinned toner in contact with a latent image carrier, wherein the toner is at least a colorant and a colorless or pale color. Containing a charge control agent and a polyester resin, the monomer constituting the polyester resin is composed of a polyhydric alcohol and a polybasic acid, and its glass transition temperature (Tg) is a variable on the x axis, and the softening point (Sp) is When plotted on the xy coordinates as a variable of the y axis, the following formula ~
A non-magnetic one-component full-color development having physical properties within a range surrounded by a straight line, wherein the surface of the toner particles further contains at least one kind of fine particle additive. For toner. Formula Sp = 4Tg-110 Formula Sp = 4Tg-170 Formula Sp = 90 Formula Sp = 120 2. The aromatic polybasic acid is at least one compound selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, their anhydrides and lower alkyl esters. 1. The non-magnetic one-component full-color developing toner described in 1. 3. The non-magnetic one according to claim 1, wherein the aromatic polybasic acid is at least one compound selected from the group consisting of terephthalic acid, anhydrides thereof and lower alkyl esters. Component full color developing toner .