JP3819319B2 - Toner for electrostatic image development - Google Patents

Description

【００３５】
【数１】

【００３６】
【表６】

【００３７】
【発明の効果】
本発明の静電荷像現像用トナーは、帯電量分布がよく、常に適度で且つ安定した帯電性を示す等の帯電性能が良好で、連続使用した場合にも安定した画像濃度が得られ、カブリ等の画像汚れもなく、或いはプリンタや複写機内のトナー飛散による汚染も少なく、更に環境変化に対しても安定した画像特性を安定して維持するなどの多大な工業的利益を提供するものである。
【図面の簡単な説明】
【図１】 参考例１の通常環境及び高温高湿環境下で５，０００枚のプリント実写テストを実施した場合のデーター。
【図２】 参考例１と参考例２の通常環境下で逆極性トナーを評価したデーター。
【図３】 参考例２の通常環境及び高温高湿環境下で５，０００枚のプリント実写テストを実施した場合のデーター。
【図４】 実施例１の通常環境下で５０，０００枚のコピー実写テストを実施した場合のデーター。
【図５】 比較例１の通常環境下で５０，０００枚のコピー実写テストを実施した場合のデーター。
【図６】 実施例１のトナーｃと比較例１のトナーｄの帯電立上り特性。[0001]
[Industrial application fields]
The present invention relates to an electrostatic image developing toner used in electrophotography, electrostatic recording and the like.
[0002]
[Prior art]
The developer used in an electronic copying machine or the like is temporarily attached to an image carrier such as a photoreceptor on which an electrostatic charge image is formed in the development process, and then transferred from the photoreceptor to transfer paper in the transfer process. Then, it is fixed on the copy paper surface in the fixing step. At that time, as a developer for developing an electrostatic charge image formed on the latent image holding surface, a two-component developer composed of a carrier and a toner and a one-component developer not requiring a carrier (magnetic toner, non-magnetic toner) ) It has been known.
[0003]
As the toner contained in the developer, there are a positively charged toner and a negatively charged toner. Conventionally, those that impart chargeability to the positively charged toner include a nigrosine dye, a quaternary ammonium salt, and the like. Known examples of imparting chargeability to negatively charged toners include charge control agents such as gold-containing dyes and coating agents that impart predetermined chargeability to carriers.
[0004]
[Problems to be solved by the invention]
However, these conventional toners do not have sufficient charging characteristics such as charge rising property, charge amount distribution, and charge holding property, and have problems to be further improved.
For example, toner charge rise characteristics (the time from when the copier is started to start mixing with the carrier until a predetermined charge amount is obtained), stability of image density during continuous use, occurrence of fog (image contamination) ) And contamination inside the machine due to toner scattering inside the copier. As another example, it is difficult to stably maintain the proper chargeability of the toner regardless of the environmental conditions (temperature, humidity, etc.), and to change the chargeability over time. When changed and used in a copying machine or the like, there are problems such as stability of image density, occurrence of image contamination such as fogging, or occurrence of internal contamination due to toner scattering.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a developer with good toner charge rising, good image density stability during continuous use, and less occurrence of fog and internal contamination due to toner scattering inside a copying machine. is there.
It is another object of the present invention to provide a developer that can obtain an appropriate chargeability and a stable image density regardless of environmental conditions such as temperature and humidity, and has less fog and toner scattering.
It is another object of the present invention to provide a toner with excellent charging characteristics that has a small amount of reverse polarity toner and exhibits a good charge amount distribution.
[0006]
[Means for Solving the Problems]
As a result of diligent examination of the problem, the present inventors have given the following means to impart an appropriate charge control effect to the toner, have a low reverse polarity, and exhibit a good charge amount distribution. The inventors have found that an excellent toner can be obtained, and have reached the present invention.
That is, the gist of the present invention is at least a resin and carbon black, and the carbon black is an acidic carbon black having a pH of 6 or less produced by a furnace method, and its DBP oil absorption is 50 to 120 ml / 100 g, and An electrostatic charge image developing toner, wherein the toluene extract filtrate has an ultraviolet absorbance of 0.02 or less.
[0007]
[Action]
Hereinafter, the present invention will be described in detail.
As the resin component that can be used in the present invention, known types suitable for toner can be used. For example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-chlorocopolymer, styrene-vinyl acetate copolymer Styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, and styrene-acrylic acid) Phenyl copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, and styrene-phenyl methacrylate copolymer) Styrene-α-chlorac Styrenic resins (monopolymer or copolymer containing styrene or styrene-substituted product), vinyl chloride resin, rosin-modified maleic acid resin, phenol, etc., such as methyl oxalate copolymer and styrene-acrylonitrile-acrylic acid ester copolymer Resin, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, polycarbonate resin, etc. Particularly preferred resins for use in the invention include styrenic resins, saturated or unsaturated polyester resins and epoxy resins. Moreover, the said resin is not restricted to being used alone, but can be used in combination of two or more.
[0008]
Furthermore, a crosslinked binder resin described in JP-B-51-23354 and JP-A-50-44836, or a non-crosslinked binder described in JP-B-55-6895 and JP-B-63-32180. Resin can also be used.
The glass transition temperature of the toner binder resin is such that the transition start temperature (inflection point) when measured by a thermal analysis method (differential thermal analyzer, differential scanning calorimetric analyzer, etc.) is 50 ° C. or higher. preferable. When the glass transition temperature is less than 50 ° C., when the toner is left for a long time at a high temperature of 40 ° C. or more, the toner is agglomerated or fixed, causing a problem in use.
[0009]
The colorant used in the present invention is not particularly limited even if at least carbon black is used and other conventionally used colorants are used in combination. Any other suitable pigment or dye can be used as the other colorant. For example, titanium oxide, zinc white, alumina white, calcium carbonate, bitumen, carbon black, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, An anthraquinone dye, monoazo and disazo dyes and pigments can be used alone or in combination with a corresponding color of toner.
[0010]
The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development. For example, it is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the resin. Further, 3 to 15 parts by weight is preferable.
The ultraviolet absorbance of the carbon black used in the present invention is 0.05 or less, preferably 0.04 or less. If it is higher than 0.05, the charging characteristics of the toner are deteriorated, which is not preferable. In other words, the present inventors particularly focused on limiting the carbon absorbance of the toluene extract to a specific value or less.
[0011]
The ultraviolet absorbance (λc) of carbon black is determined by the following method. First, 3 g of carbon black was sufficiently dispersed and mixed in 30 ml of toluene. Filter using 5C filter paper. Thereafter, the filtrate was placed in a quartz cell having a 1 cm square light absorption part, and the value (λs) obtained by measuring the absorbance at a wavelength of 336 nm using a commercially available ultraviolet spectrophotometer, and the value obtained by measuring the absorbance of toluene alone as a reference using the same method. From (λo), the ultraviolet absorbance is obtained by λc = λs−λo.
[0012]
Examples of commercially available spectrophotometers include an ultraviolet-visible spectrophotometer (UV-3100PC) manufactured by Shimadzu Corporation.
The carbon black of the present invention is produced by a furnace method.
Carbon black preferably has a specific surface area of 20 to 500 m ² / g by nitrogen adsorption by the BET method and a dibutyl phthalate (DBP) oil absorption of about 30 to 150 ml / 100 g. In particular, BET method specific surface area of 20m ² / g as low as worse particle dispersion of the increases and the only carbon black than, also dispersion of Scheer takes less of carbon black when 500m ² / g high and the particles are kneaded finer than breaking bad. In consideration of further improving the dispersibility of carbon black in the resin during toner kneading, a specific surface area of 80 to 150 m ² / g and a DBP oil absorption of 50 to 120 ml / 100 g is preferable.
[0013]
Furthermore, acidic carbon black is particularly preferable for improving the charging characteristics of the toner. Acidic carbon black refers to one having a pH of 6 or less, more preferably 5 or less, when the pH of the suspension after boiling carbon black and pure water is measured. In order to reduce the pH to 6 or less, it is only necessary to subject carbon black to an oxidation treatment by a known method. As a result, the presence of an oxidation compound or the like on the surface of carbon black is assumed to increase the miscibility of resin and carbon black in the toner. To do. Examples of the acidic type carbon black manufactured by the furnace method include MA7, MA8, MA11, MA100, # 1000, # 2200B, # 2350, # 2400B manufactured by Mitsubishi Kasei Co., Ltd., MOGUL L, REGAL 400R manufactured by Cabot Corporation, MONARCH 1000 and the like, REVEN series 1035, 1040, 1255, 3500, etc. made by Colombia are listed as specific examples. To reduce the ultraviolet absorbance of these carbon blacks, for example, by reducing the impurities of the raw materials used, by the furnace method The manufacturing conditions (for example, conditions such as processing flow rate and processing time) may be appropriately managed.
[0014]
Carbon black may be subjected to surface treatment with a metal soap or the like, if necessary, for the purpose of surface modification, or may be used in combination with an untreated one and a surface treated one at the time of use.
Furthermore, the toner of the developer of the present invention may be used with a known positively charged or negatively charged charge control agent alone or in combination, and the amount used may be selected according to the desired charge amount. The addition amount of the control agent is preferably about 0.05 to 10 parts by weight with respect to 100 parts by weight of the resin. Examples of the positive charge control agent include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, and polyamine resins. Examples of negative charge control agents include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, and alkylsalicylic acid metal compounds.
[0015]
In addition, in order to improve the fixability and fluidity as a toner component of the developer of the present invention, additives such as low molecular weight olefin polymer, fine powder silica, alumina, titania, and further resistance adjustment and lubricant Inorganic fine powders such as magnetite, ferrite, cerium oxide, strontium titanate, and conductive titania, and organic fine powders such as acrylic resins may be included as internal or external additives. The amount of these additives to be used may be appropriately selected depending on the desired performance. For example, about 0.05 to 10 parts by weight is preferable with respect to 100 parts by weight of the resin.
[0016]
In addition, as a method for producing toner particles of the developer of the present invention, various conventional toner production methods can be applied. For example, as a general example, first, a resin, a colorant, a wax, a charge control agent, and the like are mixed. Then, the mixture is melt-kneaded with a closed kneader or a single-screw or twin-screw extruder, etc., cooled, and then roughly crushed with a crusher, hammer mill, etc., jet mill, high-speed rotor rotary type Finely pulverize with a mill or the like, and classify with an air classifier (for example, a sensitivity classification type elbow jet, a centrifugal classification type microplex, a DS separator, etc.). The average particle diameter of the toner is preferably 3 to 20 μm.
[0017]
Further, when externally adding to the toner, the classified toner and the external additive may be stirred and mixed with a high-speed stirrer or the like.
The obtained toner of the developer of the present invention can also be used as a one-component developer (a magnetic one-component toner containing a magnetic material such as magnetite or a non-magnetic one-component toner containing no magnetic material) that does not use a carrier. Can do.
[0018]
When the toner of the present invention is used for a two-component developer, it may be used by mixing with a magnetic carrier. As the magnetic carrier, iron powder, ferrite powder, magnetic resin carrier and the like having an average particle diameter of about 20 to 200 μm are conventionally used. Can be used. In addition, these surfaces may be coated with a known silicone resin, acrylic resin, fluorine resin, styrene resin, epoxy resin, polyester resin, polyamide resin, or a mixture of these resins in a single layer or multiple layers. Can also be used. The ferrite core material is preferably a ferrite powder represented by the general formula (MO) m (Fe2 O3) n, and the (MO) component includes CuO, ZnO, NiO, FeO, MnO, MgO, BaO and the like. One or more components may be selected and used.
Although there is no restriction | limiting in particular in these carrier particle sizes, What has an average particle diameter of 10-200 micrometers is preferable. The mixing ratio of the carrier and the toner is preferably 5 to 100 parts by weight with respect to 1 part by weight of the toner.
[0019]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by the following example, unless the summary is exceeded.
In the following examples, “parts” simply means “parts by weight”.
< Reference Example 1>
[0020]
[Table 1]
Styrene / n-butyl acrylate = 82/18 copolymer resin 100 parts (flow softening temperature 135 ° C., glass transition temperature 64 ° C.)
Colorant: Carbon black S powder product 6 parts (manufactured by Mitsubishi Kasei Co., Ltd., UV absorbance 0.03, BET specific surface area 126 m ² / g,
DBP oil absorption 100ml / 100g, pH 3, bulk density 0.15g / cc)
・ Low molecular weight polypropylene 550P 2 parts (manufactured by Sanyo Chemical Industries)
-Charge control agent Bontron S34 1 part (Orient Chemical Industries Co., Ltd., Cr metal-containing dye)
[0021]
Were mixed, kneaded using a continuous twin screw extruder, cooled, pulverized, and classified to obtain black toner a having an average particle diameter of 12 μm. To 100 parts of the black toner a, 0.3 part of silica powder (SS50 manufactured by Nippon Silica Co., Ltd.) was externally added using a Henschel mixer to obtain toner A. The developer A was prepared by mixing and stirring 9 parts of the obtained toner A and 91 parts of a Cu—Zn ferrite powder carrier having a non-coated average particle diameter of 70 μm and a saturation magnetization of 65 emu / g.
[0022]
Next, using the start developer A and the replenishment toner A, the organic photoconductor is used as a photoconductor, and a magnetic permeability sensor is used for a heat roll fixing method, a blade cleaning method, and a toner replenishment control for the developer in the developing tank. This is a page printer with a reverse development method (photoreceptor surface potential DC-550V, buy-eye voltage DC-350V) at a printing speed of 12 sheets (A4) / min. 5,000 live-action tests were performed in an environment of% RH.
[0023]
As a result of this live-action test, the image density in the black background of the print is stable and high even during 5,000 actual shots, there is no increase in fog that is a stain on the white background of the print, and there is little toner scattering and no contamination inside the printer. Further, the toner and the developer were excellent in the transfer efficiency to the toner paper and excellent in durability performance and print image stability even after continuous printing.
[0024]
Further, 5,000 sheets of live-action tests were performed using the same developer / toner and printer as described above in an environment of high temperature and high humidity of 35 to 37 ° C. and humidity of 83 to 87 RH%.
As a result of this live-action test, the print durability and print image stability were almost the same, even in the case of 5,000-shot real shots, with no noticeable difference compared to the normal environment.
Figure 1 shows actual image data under normal environment (NN) and high-temperature and high-humidity environment (HH). As a method for evaluating reverse polarity toner under normal environment, fog change when a positive buy-eye voltage is applied. Are shown in FIG.
< Reference Example 2 >
[0025]
[Table 2]
Styrene / n-butyl acrylate = 82/18 copolymer resin 100 parts (flow softening temperature 135 ° C., glass transition temperature 64 ° C.)
Colorant: Carbon black N powder product 6 parts (manufactured by Mitsubishi Kasei Co., Ltd., UV absorbance 0.10, BET specific surface area 126 m ² / g,
(DBP oil absorption 100ml / 100g, pH 3, bulk density 0.15g / cc)
・ Low molecular weight polypropylene 550P 2 parts (manufactured by Sanyo Chemical Industries)
-Charge control agent Bontron S34 1 part (Orient Chemical Industries Co., Ltd., Cr metal-containing dye)
[0026]
A toner b was produced in the same manner as in Reference Example 1 except that the toner B was externally added and mixed with the toner B and carrier and stirred to obtain a developer B, and then 5,000 sheets as in Reference Example 1. The live-action test was conducted under normal environment and high temperature and high humidity.
The results in the normal environment showed that the toner consumption was slightly higher, the transfer efficiency was slightly worse, and the contamination of the developing tank due to toner scattering was slightly higher. Further, as an evaluation of the reverse polarity toner, it was estimated that the fog level was high when the bias change when the bias voltage was changed, and the reverse polarity toner was large. (See Figure 2)
As a result of the high temperature and high humidity environment, the transfer efficiency was poor, and the developer tank was often contaminated with scattered toner.
[0027]
FIG. 3 shows actual image data in a normal environment and a high temperature and high humidity environment, and FIG. 2 shows changes in bias voltage and fog in a normal environment.
<Example 1 >
[0028]
[Table 3]
Styrene / n-butyl acrylate = 82/18 copolymer resin 100 parts (flow softening temperature 130 ° C., glass transition temperature 61 ° C.)
-Colorant Carbon black S Granulated product 6 parts (manufactured by Mitsubishi Kasei Co., Ltd., UV absorbance 0.02, BET specific surface area 130 m ² / g,
(DBP oil absorption 100ml / 100g, pH 3, bulk density 0.28g / cc)
・ Low molecular weight polypropylene 550P 2 parts (manufactured by Sanyo Chemical Industries)
-Charge control agent Bontron P51 1 part (Orient Chemical Industries, quaternary ammonium salt)
[0029]
A black toner c having an average particle diameter of 9.5 μm was obtained in the same manner as in Reference Example 1 except that. To 100 parts of this black toner, 0.2 part of silica powder (R972, manufactured by Nippon Aerosil Co., Ltd.) and 0.3 part of magnetite powder (average particle size: 0.3 μm) are externally added using a Henschel mixer to prepare toner C. Obtained. A developer C was prepared by mixing 4 parts of the toner C obtained and 96 parts of a Cu—Zn ferrite carrier having an average particle diameter of 100 μm and a saturation magnetization of 55 emu / g, which was surface-coated with a methylsilicone-containing resin.
[0030]
Next, using the developer C for starter and the toner C for replenishment, an organic photoconductor is used as a photoconductor, and a magnetic permeability sensor is used for a heat roll fixing method, a blade cleaning method, and a toner replenishment control for the developer in the developing tank. A normal development system (photoconductor surface potential: normal mode DC-700V, photographic mode DC-500V, bias voltage; DC-200V) with a copy speed of 50 sheets (A4) / min. 50,000 live-action tests were performed in an environment of a temperature of 23 to 25 ° C. and a humidity of 50 to 55% RH.
[0031]
As a result of this live-action test, the copy image density is stable and high even when 50,000 sheets are taken, there is no increase in fog, which is a stain on the white background of the copy, and there is little toner scattering and no contamination inside the copier. The developer and toner had excellent durability performance and copy image stability even after copying.
FIG. 4 shows live-action data under a normal environment.
Further, the charge amount rising characteristic of the toner c was good as shown in FIG.
<Comparative Example 1 >
[0032]
[Table 4]
Styrene / n-butyl acrylate = 82/18 copolymer resin 100 parts (flow softening temperature 130 ° C., glass transition temperature 61 ° C.)
-Colorant Carbon black N granulated product 6 parts (manufactured by Mitsubishi Kasei, UV absorbance 0.10, BET specific surface area 130 m ² / g,
(DBP oil absorption 100ml / 100g, pH 3, bulk density 0.28g / cc)
・ Low molecular weight polypropylene 550P 2 parts (manufactured by Sanyo Chemical Industries)
-Charge control agent Bontron P51 1 part (Orient Chemical Industries, quaternary ammonium salt)
[0033]
A toner d was produced in the same manner as in Example 1 except that the toner d was added, and the externally added toner D and a carrier were mixed and stirred to obtain a developer D, and then 50,000 sheets as in Example 1 were obtained. A live-action test was conducted in a normal environment.
As a result, the image density stability in the photographic mode is poor, the initial fog is high, the amount of toner scattered on the bottom of the developing tank is large (the amount of toner scattered is about 4 times or more that in Example 1 ), and the transfer efficiency is high. However, there was a problem in durability and image stability during copying.
FIG. 5 shows actual photograph data in a normal environment.
Further, the charge amount rising characteristic of the toner d was not preferable as shown in FIG.
[0034]
[Table 5]

[0035]
[Expression 1]

[0036]
[Table 6]

[0037]
【The invention's effect】
The toner for developing an electrostatic charge image of the present invention has a good charge amount distribution, a good charging performance such as always exhibiting an appropriate and stable chargeability, a stable image density even when continuously used, and a fog. The present invention provides great industrial benefits such as stable image characteristics that are stable against image changes, and is free from contamination caused by toner scattering in printers and copiers. .
[Brief description of the drawings]
FIG. 1 shows data when a 5,000 print live-action test was performed in a normal environment and a high temperature and high humidity environment of Reference Example 1.
FIG. 2 shows data obtained by evaluating a reverse polarity toner in the normal environment of Reference Example 1 and Reference Example 2 .
FIG. 3 shows data obtained when 5,000 print live-action tests were performed in a normal environment and a high-temperature and high-humidity environment of Reference Example 2 .
4 shows data obtained when a copy live-action test of 50,000 sheets was performed in the normal environment of Example 1. FIG.
FIG. 5 shows data obtained when a copy live-action test of 50,000 sheets was performed in the normal environment of Comparative Example 1 .
[6] charge rising properties of the toner d of the electrophotographic toner c Example 1 of Example 1.

Claims (2)

At least a resin and carbon black are contained, the carbon black is an acidic carbon black having a pH of 6 or less produced by a furnace method, the DBP oil absorption is 50 to 120 ml / 100 g, and the ultraviolet absorbance of the toluene extraction filtrate is 0 A toner for developing an electrostatic image, wherein the toner is .02 or less. ^2. The electrostatic image developing toner according to claim 1, wherein the carbon black has a BET specific surface area of 20 to 500 m ² / g.

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