JPS63163374A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain a toner which exhibits stable electrostatic chargeability and has less environmental fluctuation and good transferability by incorporating a salicylic acid metal salt and/or metal salt of salicylic acid deriv. having specific characteristics into the toner. CONSTITUTION:The acicular crystal or amorphous salicylic acid metalsalt and/or metal salt of the salicylic acid deriv. sized a/b<5 and a>=5mum when the length of the major axis is designated as (a) and the length of the minor axis as (b) is incorporated into the toner. The salicylic acid metal salt or the metal salt of the salicylic acid deriv. can be expressed by formula I. In formula, R<1>-R<3> is hydrogen or alkyl group or allyl group of 1-10C, Me is any metal selected from zinc, nickel, cobalt, lead, and chromium. The toner for one component and two component type dry developers which are subjected to negative electrostatic charge control for a long period of time without impairing the intrinsic colors of color materials is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a toner for developing electrostatic images, and more particularly, to a toner for developing electrostatic images containing a compound with specific properties as a charge control agent (polarity control agent). .

[Prior art]

There are two methods for developing an electrostatic latent image formed on an electrophotographic photoreceptor or electrostatic recording material: a method using a liquid developer (wet development method), and a method using a colorant dispersed in a binder resin. A method using a toner or a one-component type or two-component type dry developer in which this toner is mixed with a solid carrier (dry development @
) is generally adopted. Although each of these methods has its own advantages and disadvantages, the dry developing method is currently widely used.

By the way, in the above-mentioned toner (developer powder), if a coloring agent such as a dye or pigment is simply dispersed in a binder resin, desired charging properties cannot be obtained, so a charge control agent (polar control agent) is added to the toner. Usually, an appropriate amount of is added. Typical examples of conventional charge control agents include (i) agents that impart a positive charge to the toner, such as nigrosine dyes, and (it) agents that impart a negative charge to the toner, such as chromium-containing monoazo complexes and chromium-containing salicylic acid compounds. Examples include metal-containing dyes such as complexes and chlorine-containing organic dyes (copper phthalocyanine green, chlorine-containing monoazo dyes). However, these conventional charge control agents are hexagonal colored substances, have poor compatibility or wettability with the binder resin, or are sublimable, so they do not have good charge control properties over a long period of time. Therefore, it is not suitable for electrophotographic toners, especially color toners.

In addition, although toners containing conventional charge control agents exhibit good development characteristics initially, they have a short lifespan, cause reverse charging during continuous copying, and do not provide stable charging properties, and have poor environmental stability. It has the disadvantage of poor stability against changes in temperature and humidity. Regarding these conventional coloring agents and charge control agents, please refer to Japanese Patent Publication No. 48-25941.
issue.

JP 48-26784, JP 49-20225, JP 50-140137, JP 50-1420
No. 37, JP-A-50-142038, JP-A-46-4
No. 3440, Special Publication No. 4g-30899, Special Publication No. 49-
No. 46423, Japanese Patent Publication No. 49-26909, Japanese Patent Publication No. 49-1973
This method is disclosed in publications such as No.-51949 and Japanese Unexamined Patent Publication No. 134303/1983.

However, in order to control the toner to be negatively charged, chlorinated paraffin, unsaturated polyester, etc. are used as binder resins, and specific polyester resins (non-linear, low melting point aromatic Although it is known to use a reaction product of a group resin and a salicylic acid chelate (Japanese Patent Application Laid-open No. 59-29259), it is difficult to obtain the desired molecular weight as a binder with these resins, and therefore The important thermal properties of a toner (melting properties on the heat roll during fixing) are not obtained, resulting in copies being wrapped around the heat roller, resulting in copy ejection errors, and offset phenomenon, in which the toner image on the paper transfers to the roller surface, making characters unclear. It was recognized that there were disadvantages such as the tendency to cause

〔the purpose〕

The first object of the present invention is to create a one-component or two-component dry developer that can be negatively charged over a long period of time without impairing the original color of the coloring material by containing a colorless polarity control agent. It provides toner. A second object of the present invention is to provide a toner for developing electrostatic images that not only always provides stable images but also is suitable for high-speed development and has excellent durability and environmental stability. A third object of the present invention is to effectively prevent toner from sticking to the sleeve or plate in a -component type developer, and to effectively prevent toner from being spent (fused) on a carrier in a two-component type developer. The purpose of the present invention is to provide a toner for developing electrostatic images.

〔composition〕

The toner for developing an electrostatic image of the present invention has a needle crystal or amorphous salicylic acid metal salt with a/b < 5 and 865 μm, where the length of the major axis is a and the length of the minor axis is b. It is characterized by containing/or a metal salt of a salicylic acid derivative.

By the way, the inventors of the present invention have researched various aspects of dry toner development characteristics, transferability, etc., and have found that metal salts of salicylic acid (especially zinc salts are preferred) as charge control agents.
It has been confirmed that good toners can be obtained when metal salts of salicylic acid derivatives (zinc salts are particularly preferred) are used. However, depending on the manufacturing conditions, salicylic acid metal salts and metal salts of salicylic acid derivatives are sometimes produced into needle-like large crystals, and when used as a charge control agent in a component-type dry developer, developing sleeves, blades, etc. Furthermore, when this is used as a charge control agent for toner in a two-component dry developer, there is a tendency for the rate of spent toner to carrier to increase. These phenomena are undesirable because they make the toner chargeability insufficient and cause fogging, white streaks, etc. on the image. Therefore, the present inventors further conducted research and found that a/b < 5 and 865 μm when the major axis is a and the minor axis is b among salicylic acid metal salts and salicylic acid derivative metal salts.
It has been confirmed that acicular crystals or amorphous materials can be used very well in toners as charge control agents.

The present invention has been made based on such knowledge.

The metal salt of salicylic acid or the metal salt of a salicylic acid derivative used as a charge control agent in the present invention can be represented by the following general formula (where R1, R2 and R3 are hydrogen or have 1 to 10 carbon atoms.
is an alkyl group or an allyl group, and hydrogen or an alkyl group having 1 to 6 carbon atoms or an allyl group are particularly preferred. Here, R1, R2 and R3 may be the same or different at the same time. Further, Me is any metal selected from zinc, nickel, cobalt, lead, and chromium, and zinc is particularly desirable. ) The metal salt represented by this general formula is CLARK.

J, L., Kao, H. (1948) J., Amer, C.
hem, Soc, 70.2151. For example, salicylic acid (including its derivatives) is dissolved in a heated water solvent with an equimolar amount of sodium hydroxide and reacted to form sodium salicylic acid salt. Further, 2 moles of the obtained sodium salicylic acid salt (including the sodium salt of salicylic acid derivatives) and 1 mole of zinc chloride are added and mixed, and the mixture is heated and stirred to obtain a zinc salt.

This metal salt is a white needle-shaped crystal, but its crystallinity can be lowered by changing the reaction temperature and the water content of salicylic acid or its derivative. For example, the reaction temperature is 60
If the temperature is higher than 0.degree. C. or the water content of salicylic acid or its derivatives is lower than 10%, the degree of crystallinity decreases, and a metal salt of salicylic acid or a metal salt of a salicylic acid derivative containing a large amount of amorphous portion is obtained.

For salicylic acid metal salts (including metal salts of salicylic acid derivatives) with high crystallinity and few amorphous components, the length of the long axis and the length of the short axis of the crystal are a and b, respectively. , a/b > 5 or a ) 5 μm in most cases. Now, such salicylic acid metal salt (a/
If a metal salt of a salicylic acid derivative with b > 5 or a > 5 μm) is used as a charge control agent for toner, as mentioned above, in the case of a -component type developer, the toner will not stick to the developing sleeve or developing blade. This tends to occur, and in the case of two-component developers, toner spend (fusion) on the carrier.
The amount increases. As a result, the triboelectric charge to the toner is insufficient, and the -component type developer has a lot of ground force blur.
This results in a poor image with streaky white spots, and a two-component developer results in a poor image with a lot of ground blur and low image density.

However, if salicylic acid metal salts (including metal salts of salicylic acid derivatives) are used, which are relatively small needle-like crystals with a/b<5 and 855 μm or are amorphous, the above-mentioned problems do not occur. .

Figures 1 to 4 summarize these results based on actual measurements.

Figures 1 and 2 are test results using the one-component development method.
Figure 1 shows the ratio of the long sleeve length a of the crystal to the short axis length b (a
/b ratio), and FIG. 2 shows the relationship between toner adhesion to the developing blade and the length of the long axis a of the crystal.

The one-component developer (toner) used here was a styrene-n-butyl methacrylate copolymer (polymerization molar ratio 75/25) 100
A mixture consisting of 5 parts by weight of copper phthalocyanine blue was melt-kneaded using a hot roll mill, cooled, pulverized using a jet mill, and classified using an air classifier, and the resulting product had a particle size of 5 to 25 μm. In addition, the detailed test method was applied to the developing section of an electrophotographic copying machine (Mylicopy-M5 manufactured by Ricoh Corporation), which uses a developing method in which the developing blade is brought close to the developing sleeve to form a thin layer of toner and a frictional charge is applied to the toner. 50g of the above toner was supplied, and the developing sleeve was run idly in an electrophotographic copying machine for 5 hours continuously, and the surface of the developing blade adjacent to the sleeve was
This was done by comparing and evaluating whether or not the toner was stuck. In this case, the toner is in non-consumable mode.

On the other hand, FIGS. 3 and 4 show test results using a two-component development method, and show the amount of spent toner in the carrier with respect to the a/b ratio and the length a of the major axis of the crystal. The two-component developer used here was a carrier (average particle size 100 μm).
This is a mixture of 97 parts by weight of iron oxide powder (M) and 3 parts by weight of the toner. In addition, the detailed test method is to put this two-component developer into a 100m Q stainless steel pot, stir it for 24 hours, then separate the toner and carrier by blow-off, and add 1000m of solvent that dissolves only the toner to the carrier log. Add Q and use an ultrasonic cleaner for 5
By washing for minutes, evaporating the solvent, and accurately weighing the carrier weight before and after such treatment on a chemical balance,
The percentage of the difference with respect to the weight of the carrier before treatment was defined as the amount of spent toner.

As can be seen from these test results, when the a/b ratio of -component type developer (-component toner) is 5 or more, toner often sticks to the developing blade.

Similarly, when the value of a is larger than 5 μm, toner sticks to the developing blade. On the other hand, when the a/b ratio of toner using a two-component developer is greater than 5, the amount of spent toner to the carrier exceeds 0.06% by weight.
Further, if the value of a is larger than 5 μm, the amount of spent toner becomes 0.08% by weight or more, and the charging ability of the carrier to the toner is substantially reduced, making it impossible to obtain sufficient triboelectric charging.

The reason for this inconvenience is that when the salicylic acid metal salt (including its derivative metal salts) is in the form of needle-like large crystals, it is insufficiently dispersed in the binder resin, resulting in an interface between the binder resin and the salicylic acid metal salt. For this reason, -component development methods, especially methods in which a developing blade and a developing sleeve are brought close to each other to form a thin layer of toner,
If a strong shearing force is applied to the toner during agitation of the developer in a two-component development system, the toner is likely to be destroyed and the toner becomes finely powdered, causing the above-mentioned problems.

The toner of the present invention is produced using a colorant and a binder resin as essential components, as well as a compound (charge control agent) that satisfies the following conditions: a/b<5 and a≦5. In the present invention, two or more types of charge control agents may be combined.

Conventional colorants used in the present invention include magenta, cyan,
All of the colorants used as colorants for color toners such as yellow can be used.

Specifically, inorganic pigments such as ultramarine, navy blue, silica, alumina, and titanium; azo dyes and pigments, anthraquinone dyes and pigments, phthalocyanine dyes and pigments, quinacridin dyes and pigments,
Examples include organic dyes and pigments such as perylene dyes and pigments, indigo dyes and pigments, basic dyes, and lake salts thereof. Two or more of these colorants can also be used in combination.

If desired, the use of a black coloring agent such as carbon black may also be considered. Among these colorants, it is particularly desirable to use phthalocyanine dyes and pigments and benzidine yellow pigments.

Representative examples of phthalocyanine pigments include C and I.

Pigment Blue 15, C, 1, Pigment Blue 16
, C,1, Pigment Blue 17, C,1, Pigment Green 7, C,1, Pigment Green 12, C,1
, Pigment Green 36, C,1, Pigment Green 3, C,1, Pigment Green 38, etc. Representative examples of phthalocyanine dyes include C,1, Solvent Blue 25, C,1, Solvent Blue 55,
C1■, Solvent Blue 0. Examples include C,1, Direct Blue 25, C,1, Direct Blue 86, etc.

Modified versions of these phthalocyanine dyes and pigments can also be used effectively, and these phthalocyanine dyes and pigments can also be blended with other coloring agents exhibiting blue or green colors.

Representative examples of benzidine yellow pigments include benzidine yellow (C0I, 21090) benzidine yellow GR (C,1,21090) benzidine yellow FGR
(C,1,21100)Benzidine Yellow GE (C
, 1, 21100).

Further, as for the binder resin used in the present invention, all of the binder resins that have been used hitherto as binder resins for toners can be used as well as the above-mentioned colorants. Specifically, styrene such as polystyrene, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, and styrene-butadiene copolymer Including system resins, saturated polyester resins, unsaturated polyester resins, epoxy resins, phenolic resins, maleic acid resins, coumaron resins,
Chlorinated paraffin, xylene resin, vinyl chloride resin,
Examples include polypropylene and polyethylene.

It goes without saying that two or more of these binder resins may be used as a mixture as appropriate; among these, it is advantageous to use polystyrene, styrene resins, and epoxy resins.

In addition to the above-mentioned components, the toner of the present invention contains various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.), resistance adjusters ( It is also possible to add auxiliary agents such as tin oxide, lead oxide, antimony oxide, etc.).

The amount of the metal salt in the toner is about 0.1 to 30 parts by weight, preferably about 0.5 to 7 parts by weight, based on 100 parts by weight of the binder resin. The amount of the colorant in the toner is about 0.1 to 10 parts by weight, preferably about 1 to 7 parts by weight, based on 100 parts by weight of the binder resin.

Furthermore, in the present invention, after producing toner particles (5 to 20 μm), fine powders such as TiO2, 11□O, SiO, etc. are added to the toner particles and the surfaces of the toner particles are coated with the particles, thereby improving the fluidity of the toner. It is also effective to modify the photoreceptor or add zinc stearate, phthalic acid, etc. to prevent deterioration of the photoreceptor.

As mentioned above, the toner of the present invention can be used as a two-component developer (non-magnetic toner) using a touchdown method, or can be used as a regular one-component toner by adding and dispersing a magnetic material (such as magnetite powder). Furthermore, it is possible to mix it with a carrier and use it as a two-component developer.

As a carrier, iron powder with a particle size of about 50 to 300 μm,
Nickel powder, ferrite powder, glass peas, etc. are used as a core material, and the surface is coated with styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic ester polymer, methacrylic ester polymer. , silicone resin, polyamide resin, ionomer resin, polyphenylene sulfide resin, or a mixture of these resins is used. In particular, when a specific metal salt (a compound such as a zinc salt of salicylic acid and/or a zinc salt of a salicylic acid derivative) is added to the toner of the present invention, it is possible to obtain a more desired amount of the metal salt. In order to provide a stable negative charge, when the carrier is provided with a coating resin, it is advantageous to use a silicone resin or a silicone resin in which conductive fine powder is dispersed.

Note that salicylic acid or a metal complex of salicylic acid may be used as a charge control agent (Japanese Unexamined Patent Publication No. 55-42752).
is known, but as will be seen below, this method does not produce the effect intended by the present inventors.

Next, examples and comparative examples will be shown. All parts herein are parts by weight.

Example 1 Styrene-n-butyl methacrylate copolymer 100 parts Copper phthalocyanine blue (Lionol Blue KL manufactured by Toyo Ink Co., Ltd.) 5 parts 3.5-ditertiary-butylsalicylic acid zinc salt (a/
b=2.1. a=3.5 μm) Three parts were melt-kneaded using a hot roll mill, and after cooling, they were coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. The obtained fine powder was classified to have a particle size of 5 to 20 μm to prepare a blue toner according to the present invention. 3.5 parts of this toner and carrier (spherical ferrite powder with a particle size of about 100 μm and a silicone resin coating layer with a film thickness of 1 μm)
A two-component dry developer was prepared by mixing with 100 parts of the following. The amount of charge measured by the blow-off method was -18 μc/g.

Using this developer, 10℃15%RH120℃60%
When development was carried out using a dry type electrophotographic copying machine (Coby FT5050, manufactured by Ricoh Co., Ltd.) under an RH environment, a clear blue toner image without fogging, transfer omission, blurring, etc. was obtained. Further, no deterioration in copy quality was observed even after 100,000 copies were made continuously. Furthermore, 30℃, 9
Even though too many sheets were continuously copied in an environment of 0% RH, the image quality did not change and good quality was maintained. When a chromium salt was used in place of the zinc salt, it was found that good results were obtained, although slightly inferior to the zinc salt. Also,
When the amount of spent toner was measured using the above method, it was 0.0.
It was confirmed that the amount was extremely low at 28% by weight.

Comparative Example 1 A comparative toner was prepared in exactly the same manner as in Example 1, except that the toner components were replaced with those shown below, and a two-component dry developer was prepared.

The charge amount of this comparative developer by the blow-off method was -7 μc.
/g.

Subsequently, development was carried out in the same manner as in Example 1 using this comparative developer, and a clear blue toner image without fog was obtained at the initial stage of copying.

However, when 100,000 sheets were continuously copied, fogging occurred in the background area, the image density was low, the image quality was poor, and the amount of charge decreased to -2 μc/g.

Furthermore, when the amount of spent toner was measured using the method described above, it was confirmed that it was 0.173% by weight, which was extremely large.

Comparative Example 2 A slightly greenish blue toner was prepared in exactly the same manner as in Example 1 except that the toner components were replaced with the following.
A two-component dry developer was used.The charge amount of this comparative developer by the blow-off method was 113μ.
It was measured as c/g.

Subsequently, development was carried out in the same manner as in Example 1 using this comparative developer, and a slightly cloudy blue copy was obtained.

Furthermore, after 5,000 sheets were continuously copied, the charge amount of the developer by the blow-off method decreased to -6 μc/g, resulting in an unclear image with dirty background parts. Furthermore, 30℃, 9
When continuous copying was performed in an environment of 0% R)l, the amount of charge decreased to -3 μc/g, and the background area became even more dirty.

Example 2 The pigment of Example 1 was used as a yellow dye (Neozapone Yellow 073).
) A toner according to the present invention was prepared in exactly the same manner as in Example 1, except that the above was replaced with 2-component type dry developer.

The amount of charge determined by the blow-off method was -20 μc/g.

Subsequently, development was performed using this developer in the same manner as in Example 1, and a yellow toner image without fog was obtained. Furthermore, no deterioration in copy quality was observed even after 80,000 copies were made continuously. It was confirmed that the amount of spent toner was very small at 0.033% by weight.

Example 3 A red toner having a particle size of 5 to 20 μm according to the present invention was prepared in exactly the same manner as in Example 1, except that the toner components were replaced with those shown below, and a two-component type dry developer was prepared. The amount of charge determined by the blow-off method was -21 μc/g.

Naphthol Red FGR (manufactured by Hoechst) 5 parts Using this developer, an electrophotographic copying machine manufactured by Ricoh (FT4060)
), 90,000 stable and good red copies were obtained.

Further, it was confirmed that the amount of spent toner was very small at 0.044% by weight.

Comparative Example 3 The charge control agent of the toner component was replaced with zinc 3,5-ditertiary-butylsalicylate (Bontron E-
84, a/b=11.3. A toner was prepared in exactly the same manner as in Example 3, except that a=4.8 μm), and a two-component developer was prepared. The amount of charge determined by the blow-off method was -21 μc/g.

Subsequently, development was carried out in the same manner as in Example 3 using a rice developer, and a red copy without fog was obtained at the initial stage.

However, after continuous copying of 75,000 sheets, the amount of charge was 18μ.
c/g, resulting in an image with a lot of fog in the background area. Further, it was confirmed that the amount of spent toner was as high as 0.123% by weight.

Example 4 A green toner having a particle size of 5 to 20 μm according to the present invention was prepared in exactly the same manner as in Example 1, except that the toner components were replaced with those shown below, and a two-component dry developer was prepared. The amount of charge determined by the blow-off method was -15 μc/g.

Using this developer, a Ricoh electrophotographic copying machine (FT40) was used.
When 80,000 sheets were continuously copied using 60), 80,000 stable and good red copies were obtained.

Further, it was confirmed that the amount of spent toner was 0.021%, which was very small.

Example 5 A toner having a particle size of 5 to 20 μm according to the present invention was prepared in exactly the same manner as in Example 1, except that the toner components were replaced with those shown below, and a two-component dry developer was prepared. The amount of charge determined by the blow-off method was -20 μc/g.

13 parts of carbon black When this developer was used for development in the same manner as in Example 1, a fog-free black toner image was obtained. No deterioration in copy quality was observed even when too many copies were made continuously.

In addition, when this toner was used to produce an image using an electrophotographic copying machine that adopted the touchdown development method (Reversal developing machine Myricopy-M5 manufactured by Ricoh), the amount of charge on the toner on the developing sleeve was -8 μc/ A clear black image with no fog was obtained at g. No deterioration in copy quality was observed even after 30,000 continuous copies were made. Note that the value of the charge amount of the toner here is determined from the amount of charge flowing when sucked from above the developing sleeve and the amount of attracted toner. Furthermore, no toner adhesion was observed in these cases.

Comparative Example 4 The charge control agent of the toner component was 3.5-ditertiary-butylsalicylic acid zinc salt (a/b=12.3. a=5.
A toner was prepared in the same manner as in Example 5, except that the toner was replaced with 8 μm), and an image was formed using Mycobee M5 manufactured by Ricoh. A clear black image with no fog was obtained. However, after continuous copying of 20,000 sheets, the amount of charge decreased to -2 μc/g, resulting in poor images with white streaks and a lot of ground blur. Furthermore, it was observed that toner adhesion to the developing blade occurred frequently, and toner filming to the developing sleeve also occurred.

Example 6 A toner having a particle size of 5 to 15 μm was prepared in exactly the same manner as in Example 1 except that the toner components were replaced with those shown below.

Fe, O, (Er'T500 manufactured by Toda Kogyo Co., Ltd.)
50 copies When this toner was used to create an image using an electrophotographic copying machine that adopted the touchdown development method (Reversal developing machine Mycobee M10 manufactured by Ricoh), the amount of charge of the toner on the developing sleeve was -IO μm 1 g, and there was no fog. A clear black image was obtained.

No deterioration in copy quality was observed even after 30,000 continuous copies were made. Further, no occurrence of toner sticking was observed.

Example 7 The same procedure as in Example 1 was carried out except that the toner component was replaced with 50 parts of the following saturated polyester resin, with a particle size of 5 to 20 μc/
When H toner was prepared and an image was formed using a reversal developing machine (Mairicopy M10 manufactured by Ricoh), the amount of charge of the toner on the developing sleeve was -13 μc/g, and a clear image without fogging was obtained. Further, no deterioration in copy quality was observed even after 20,000 copies were made continuously. Further, toner sticking to the developing blade and toner filming to the developing sleeve did not occur.

〔effect〕

As is clear from the description of the examples, the toner of the present invention containing a salicylic acid metal salt and/or a metal salt of a salicylic acid metal salt with specific properties exhibits stable charging properties, has little environmental fluctuation, and has good transferability. Because of its good quality, it is also effective for making many copies.

[Brief explanation of the drawing]

Figures 1, 2, 3, and 4 show the properties of metal salts of salicylic acid derivatives, toner adhesion to the developing blade, and the appearance of spent particles on the carrier when metal salts of salicylic acid derivatives are contained in the toner. This is a graph showing the relationship between.

Claims (1)

[Claims] 1. When the length of the major axis is a and the length of the minor axis is b, a/b
A toner for developing an electrostatic image, characterized in that it contains a needle-shaped crystal or amorphous metal salt of salicylic acid and/or a metal salt of a salicylic acid derivative with <5 and a≦5 μm.