JPS61190344A - Toner for electrostatic photography - Google Patents

Abstract

PURPOSE:To improve a printing resistance of the titled toner in a dry lithography by incorporating a polyester resin and a prescribed amount of at least one of compds. selected from a complex compd. or its salt of a metal having two or more valencies. CONSTITUTION:The titled toner is prepared by incorporating the polyester resin and 5-25wt% at least one of the compds. selected from the complex compd. or its salt of the metal having two or more than two valencies on the weight basis of said polyester resin. Said polyester resin has preferably >=45 deg.C, more preferably >=50 deg.C glass transition temp. and has preferably 100-150 deg.C softening point. The compounding metal has 2-5 valencies and comprises calcium, magnesium and a copper. The compounding metal salt comprises magnesium acetate, aluminium acetate and ferric chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic toner, and more particularly to an electrophotographic toner that has high adhesion to a waterless lithographic printing plate material.

[Prior art] An electrostatic waterless lithographic printing plate is a method in which an ink-repellent material such as silicone is coated on the surface of a support such as paper or plastic film, and an ink-receptive toner is statically applied on the surface of a support such as paper or plastic film. The image was formed using an electrophotographic method. To print using the printing plate obtained in this way, if you ink the entire surface of the printing plate directly without using dampening water, the ink will not adhere to the silicone coated surface and the image will be formed. Since the toner adheres only to the applied toner, printing is possible by transferring this to the printing material.

Conventionally, it is well known that toners contain metal complex compounds. For example, the metal complex salt compound proposed in JP-A-59-228259 has enhanced negative charging characteristics and excellent compatibility with the binder resin of toner, and is used as a general negatively charging charge control agent. Although effective, it has no effect at all on improving the adhesion of toner to ink-repellent substances such as silicone, which is the object of the present invention. Also, JP-A-59-223455 and JP-A-59-
No. 223456 discloses that in a toner using a non-linear aromatic polyester resin and a low molecular weight polypropylene as a binder resin, an organometallic compound consisting of a divalent or higher metal is added as a charge control agent to the binder resin in an amount of 2 to 30%. Although it has been proposed to add 4% by weight, it has little effect on improving the adhesion of toner to ink-repellent substances such as silicone, which is the object of the present invention.

As described above, all metal complex salt compounds conventionally added to toners have been used only as charge control agents.

[The same layer point to be solved by the invention] The waterless lithographic printing method using electrostatic photography as described above has the following problems:
Since plate making is easy and dampening water is not required during printing, it would be an extremely innovative method if good printed matter could be obtained without any trouble, but unfortunately there are still various problems. The biggest problem is that ink-repellent substances such as silicone repel not only ink but also other substances, so they reject the toner that should adhere and become the image area, making it impossible to create sufficient adhesion. , toner falling off during printing. Even when a toner image is formed on a waterless lithographic printing plate by an electrostatic method, the image is formed using a conventionally known commercially available toner, and even if it is for waterless lithographic printing, No special toner is used. That is, at present, little consideration is given to toner in waterless planographic printing. Commonly used toners are designed to adhere to cellulose-based plain papers or treated papers with relatively hydrophilic surfaces; It is unlikely that they would show similar affinity. Many of the toners conventionally used are, for example, epoxy resin-based, polyester resin-based, or vinyl resin-based. These toners have an extremely low adhesion to waterless lithographic printing plate materials, and in some cases there is a problem in that even several dozen sheets cannot be printed.

Conventionally, proposals have been made to modify the silicone or fluorine compound polymer, which is the ink-repellent layer, in order to improve the adhesive strength with toner (for example, Japanese Patent Application Laid-Open No. 11-1989)
No. 03, JP-A-52-29305, JP-A-Sho 5
2-76104, JP-A-54-163101, etc.). These proposals attempt to introduce toner-friendly polar groups into the ink-repellent layer, but the current situation is that sufficient adhesion cannot be obtained as long as conventional toners are used.

[Means for Solving the Problems] The present invention provides at least one compound selected from a polyester resin and a complex compound or salt of a divalent or higher valent metal added in an amount of 5 to 25% by weight to the polyester/resin. The present invention relates to an electrostatic photographic toner characterized by comprising a composition containing one kind of compound.

The present invention will be explained in detail below.

Conventionally known polyester resins can be used as the polyester resin used in the present invention, as long as they have at least a hydroxyl group and/or a carboxyl group at the end of the molecular chain. Such polyester resins are obtained by polycondensation of dicarboxylic acids or their anhydrides and polyols.

Examples of dicarboxylic acids and soo include maleic acid, fumaric acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sepatic acid, malonic acid, and their anhydrides. However, it is not limited to these. In addition, if necessary, trivalent carboxylic acids such as
A small amount of 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, etc. may be used. Examples of polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1.3-70 pyrene glycol, 1.3-butanediol, 1.4-butanediol, neopentyl glycol, and 1.4-butanediol. -butynediol, 1,4-bis(
hydroxymethyl)cyclohexane, bisphenol A
, hydrogenated bisphenol A1 polyoxyethylated bisphenol A,E)-dihydroxymethylbenzene,
Glycerol, trimethylolethane, trimethylolpropane, 2-methylpropanetriol, nlubitol, pentaerythritol, 1,2. Examples include, but are not limited to, il-butanetriol, 1,2,5-pentatriol, and the like.

The polyester resin used in the present invention can be produced by a conventionally known method, for example, usually in an inert atmosphere with a width of about 20 m
It is appropriate to carry out the reaction at 0°C. At this time, catalysts commonly used in the production of polyester resins, such as tin oxide, zinc oxide, and diptyltin oxide, can also be used.

It is desirable that the polyester resin used in the present invention has a glass transition temperature of 45°C or higher, preferably 50°C or higher, and a softening point (ring and ball method) of 90 to 170°C.
, preferably 100 to 150°C.

If the glass transition temperature is lower than 45° C. or if the softening point is lower than 90° C., blocking may easily occur in the finally prepared toner, which is not preferable.

Further, if the softening point exceeds 170° C., the final toner fixation method tends to deteriorate, which is not preferable.

The above-mentioned polyester resin alone has insufficient adhesion to a direct plate material for waterless planographic printing coated with an ink-repellent substance such as silicone.

In order to impart sufficient adhesive strength, it is extremely important to add a specific amount of metal complex compound or metal salt. Metals that can be used have a valence of divalent to pentavalent, such as calcium, beryllium, magnesium, zinc, copper, aluminum, tin, cobalt, iron, chromium, manganese, molybdenum, nickel, titanium, zirconium, and lead. and vanadium.

The metal complex compounds used in the present invention include aluminum acetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisethylacetoacetate, iron (I[)7
Cetyl acetonate, cobalt (III) 7 cetyl acetonate, chromium acetylacetonate, copper (If) acetylacetonate, manganese (n) acetylacetonate, molybdenum oxyacetylacetonate, nickel acetylacetonate, titanium (Illr) oxy Examples include acetylacetonate, zinc acetylacetonate, zirconium acetylacetonate, and the like. Particularly preferred metal complex compounds include complex compounds of aluminum, iron, cobalt and titanium.

In addition, metal salts include magnesium acetate, calcium acetate, barium acetate, aluminum acetate, stannous acetate, zirconium oxyacetate, chromium acetate, manganese acetate, manganese acetate, nickel acetate, copper acetate, nickel formate, zinc acetate, Examples include cobalt acetate, ferric chloride, ferric naphthenate, cobalt naphthenate, stannous octene acetate, zinc octenoate, etc. Particularly preferred are carboxylates of aluminum, cobalt and iron, and ferric chloride. Two irons are mentioned.

It is also possible to use two or more of these compounds in combination. Additionally, some of these compounds are used as accelerators during the production of polyester resins, but the amount is very small (usually 0.1% by weight or less/monomer charged) and does not provide sufficient adhesive strength. I can't demonstrate my abilities.

It is important to add the above metal complex compound or salt in a total amount of 5 to 25% by weight, more preferably 7 to 15% by weight, based on the polyester resin. If the amount added is less than 5% by weight, sufficient adhesive strength cannot be obtained. On the other hand, if it exceeds 25% by weight, there is a risk that the heat applied during production will cause a partial crosslinking reaction in the middle of the polyester resin, leading to problems such as a significant increase in the melting point and a decrease in grindability.

The function of the metal complex compound or metal salt used in the present invention is not to function as a charge control agent as described above, but to improve the adhesive force between an ink repellent substance such as silicone and toner, and to The amount used as a control agent does not provide sufficient adhesion. The reason why the presence of a metal complex compound or salt increases the adhesion between an ink repellent substance such as silicone and the toner is that the metal complex compound or salt increases the adhesion between the functional group or polar group present in the ink repellent substance and the toner. This is thought to be due to coordination or partial reaction with carboxyl groups and/or hydroxyl groups present in the polyester resin, which is the binder resin, resulting in a strong bond between the toner and the ink-repellent substance.

Although these toner resins and metal complex compounds or metal salts alone exhibit sufficient adhesive strength, a silane coupling agent may be added for the purpose of improving the toner wetting characteristics to ink-repellent silicone or the like. As the silane coupling agent, γ-aminopropyltriethoxysilane, β-
Aminoethyl-γ-aminopropyltrimethoxysilane, γ-aminopropylmethyljethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc. Preferably used.

The toner of the present invention is characterized by the combination of a base polymer and a metal complex compound or metal salt, which can also be called an adhesion promoter, and the colorant and additives for improving process characteristics and image characteristics are conventionally known. You can use the following. Generally, polyester resins have appropriate triboelectric charging properties by themselves, so a charge control agent is not particularly required, but a small amount may be added if necessary. As the colorant, carbon black, various dyes, coloring pigments, etc. are used, but the colorant is not necessarily required when used as an image area of a printing plate material. That is, the toner only needs to ink ink and transfer it to printing paper to perform printing. Additives that improve process characteristics and image characteristics include fluidizing agents, antiblocking agents, photoreceptor surface abrasives, toner filming inhibitors, toner charging aids, and photoreceptor surface scratch preventive agents. Specifically, SiO2, Au20
3, inorganic oxides such as CeO2, and known ones such as polytetrafluoroethylene and polyvinylidene fluoride.

The appropriate composition ratio of the colorant in the air is 0 to 20 parts by weight of the colorant per 100 parts by weight of the binder resin consisting of a polyester resin and a metal complex compound or metal salt.

Further, it is also possible to form a one-component magnetic toner by using magnetic powder such as magnetic iron oxide and the resin of the present invention. As the magnetic powder, conventionally known materials are used, such as alloys or compounds containing ferromagnetic elements such as ferrite and magnetite, iron, cobalt, and nickel, or manganese that becomes ferromagnetic through appropriate heat treatment. −
Examples include alloys such as copper-aluminum, manganese-copper-tin, and chromium dioxide.

The toner of the present invention has a strong affinity for waterless lithographic printing plates having silicone or fluorine compound resin as a surface coating layer, and needless to say, it also has fixability on the surface of ordinary paper and processed sheets. Use highly functional toner. In particular, the toner is designed to adhere to ink-repellent silicone or fluorine compound resin surfaces.

Preferred examples of plate materials having a silicone or fluorine compound resin layer to which the toner of the present invention is applied include the following.

■ JP-A-56-62253, JP-A-57-49
598 and JP-A-57-36699, which support compositions containing as essential components the following three components: organopolysiloxane, polar group-containing alkoxysilane, and organotitanium or zirconium compound containing a metal-oxygen bond. Painted on the body.

■ JP-A-54-163101, JP-A-56-1
A composition mainly consisting of a reaction product of a polymer having at least two hydroxyl groups per molecule and an organic polysiloxane containing a terminal OH group as shown in Japanese Patent No. 09788 is coated on a support.

(2) A cured silicone composition having a reactive organic group-containing organosiloxane unit disclosed in JP-A-52-29305 is coated on a support.

(2) A support coated with a fluorine compound disclosed in JP-A-52-76104.

All of these contain in their molecules, in addition to a dimethylsiloxane unit or a fluorine-containing group, a compound that has an affinity with the toner of the present invention.

The toner of the present invention is image-formed on a plate material coated with silicone or fluorine compound resin having the above composition by electrophotographic engraving of PPC or CPC method, electrostatic recording method, or the like. Toner fixation may be further applied if necessary, but
It is appropriate to heat the mixture at 100 to 250°C for 10 minutes or less. The obtained printing plate is printed by an offset printing or direct printing type printing machine without supplying dampening water.

Some conventional inks can be used with water, but in general, inks specially designed for use without water are used.

[Examples] The present invention will be described in detail below, but these examples are not intended to limit the technical content of the present invention.

Example 1 Polyester resin (manufactured by Naedo Soap Co., Ltd., rATR200
5J, glass transition temperature 58℃, softening point 102.5℃)
94 parts by weight of iron (III) 7cetylacetonate and 6 parts by weight of iron (III) 7cetylacetone are dissolved in 60 parts by weight of chloroform by heating (70° C.). Furthermore, 5 parts by weight of carbon black (manufactured by Mitsubishi Chemical Industries, Ltd., rMA-8J) and 0.1 part by weight of stearic acid amide were added to this solution in 40 parts of chloroform. Add a slurry liquid that has been stirred for about 10 minutes using a homomixer at a speed of 10 ooor, p, m, for about 10 minutes. After mixing, the mixture was stirred at 70°C for about 30 minutes, and the solvent was distilled off under vacuum to obtain a solid.

The solid matter was roughly pulverized into granules with a particle size of about 2 mm or less, and then further finely pulverized and classified to obtain a toner with an average particle size of 10.5 μm.

Example 2 93 parts by weight of the polyester resin used in Example 1, iron (I
II) A toner having an average particle diameter of 1o and 3μ was obtained in the same manner as in Example 1 except that 7 parts by weight of aluminum acetylacetonate was used instead of 7cetylacetonate.

Example 3 The same procedure as in Example 1 was conducted except that 91 parts by weight of the resin used in Example 1 and 9 parts by weight of naphthene cobalt were used instead of iron (I [>7 cetyl acetonate).
, 3μ toner was obtained.

Example 4 A toner having an average particle size of 10.4 μm was obtained in the same manner as in Example 1 except that 2 parts by weight of γ-glycidoxypropyltrimethoxysilane was added to the grains.

Comparative Example 1 The same operation as in Example 1 was carried out except that the polyester resin was 100 parts by weight and iron (III) acetylacetonate was not added, and a toner with an average particle size of 10.5 μm was produced. Obtained.

The toners obtained in the above Examples and Comparative Examples were mixed with a carrier (magnetic iron powder rT E F V250/400 J, manufactured by Nippon Tetsuko Co., Ltd.) (toner concentration 10%), and a Canon NP5100 Copy III (Canon Plate-making and copying were carried out using a commercial printer (manufactured by Co., Ltd.). Images formed on plain paper and waterless lithographic printing plates were clear and free of smudges.

The waterless lithographic printing plate material used here was cast coated paper (manufactured by Kanzaki Paper Co., Ltd., mirror coated paper gold, basis weight 1270/m') with a silicone composition of 3 g/i' in dry weight. It was coated so that The silicone composition consisted of polydimethylsiloxane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and dipropoxytitanium bisacetylacetonate, and after coating on the base paper, it was heated at 160°C for 2 minutes. Heat treatment was performed.

Each toner image was formed on the waterless lithographic printing plate material described above using the above-mentioned copying machine, and after heat treatment at 160° C. for 2 minutes in a hot air open environment, printing was performed using the obtained printing plate. Waterless printing was performed using a Ricoh Auto Printer 2600 (manufactured by Ricoh Co., Ltd.) as a printing machine.

As a result, as shown in Table 1, the toner of the present invention had excellent printing durability, and no dropout of minute halftone dots was observed even after printing 1000 sheets.

[Effects of the Invention] As explained above, the toner of the present invention has extremely excellent printing durability in waterless planographic printing, and the toner that conventionally had poor adhesive strength and could not be printed on a large number of sheets. Printing can now be performed with virtually no skipping of halftone dots, etc.

Claims (1)

[Claims] (1) Consists of a composition containing a polyester resin and at least one compound selected from complex compounds or salts of divalent or higher valent metals added in an amount of 5 to 25% by weight based on the polyester resin. An electrostatic photographic toner characterized by: