JPS5924865A - Dry toner for electrophotography - Google Patents

Abstract

PURPOSE:To obtain a toner superior in offset resistance, etc., by using a resin obtained by copolymerizing a monomer containing styrene (derivative) with a precursor resin which is obtained by the reaction among an epoxy resins, a mold releasing compound having a radical which reacts upon this resin, and a polymerizable unsaturated carboxylic acid. CONSTITUTION:A polymerizable unsaturated precursor resin is prepared by the reaction among the epoxy resins which has a melting point of >=20 deg.C measured by the Durran's mercury method, a polymerizable unsaturated carboxylic acid, and a wax or an organopolysiloxane having a functional group (COOH, NH2) which reacts upon the epoxy resin. A resin obtained by copolymerizing a monomer mixture, which contains >=50wt% styrene derivative to the whole of the monomer, with this precursor resin is used as a binder to produce a toner. The ratio of the precursor resin to the monomer is 1:9-9:1, and the softening point of the binder resin is set to 80-170 deg.C. Thus, the obtained toner is superior in moisture resistance and offset resistance and has a high compatibility to a plasticizer especially, and a toner image copied to a sheet consisting of vinylchloride or the like is not transferred to the rear face of another sheet even if the sheets are piled up and are preserved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry toner for electrophotography, and more particularly to a dry toner having improved plasticizer resistance, moisture absorption resistance, and offset resistance.

There are a variety of synthetic resins currently used as binders for dry toner, but the required electrical properties,
Styrene resins, epoxy resins, polyester resins, and the like are often used in order to satisfy various properties such as mechanical properties and thermal flow properties. Among these, styrene-based or styrene-acrylic resins are particularly widely used because they have appropriate crushability, good resistance to moisture absorption, and a wide range of resin design possibilities. However, such styrene-based or styrene-acrylic resins have the property of easily dissolving in plasticizers such as dioctyl phthalate and dibutyl phthalate, so it is difficult to form images on transfer sheets with toners using these resins. After the toner image is formed, a polyvinyl chloride sheet containing a plasticizer is pressure-bonded to the transfer sheet and left for a certain period of time, so that the plasticizer in the polyvinyl chloride sheet migrates into the toner image. Therefore, if these two sheets are not separated, a portion of the toner image, or in extreme cases, the entire toner image will be peeled off from the transfer sheet and transferred to the polyvinyl chloride sheet. On the other hand, since epoxy resins have the property of being difficult to dissolve in the above plasticizers, toners using epoxy resins do not exhibit the above phenomenon of plasticizer migration and resulting toner image transfer. do not have.

Epoxy resins are excellent in that they do not undergo plasticizer migration (hereinafter referred to as plasticizer resistance), but the resin has a high hygroscopic property, which affects the toner's charge storage properties. This has the drawback of causing deterioration of the toner image in the copying machine.

In recent years, copied materials are often filed and organized on polyvinyl chloride transparent sheets, and in this case, undesirable toner image transfer as described above often occurs. In view of this point, the inventors of the present invention
In No. 4, we proposed a dry toner for electrophotography that has improved moisture absorption resistance without impairing the good plasticizer resistance of the epoxy resin.

On the other hand, as copying speeds have increased in recent years, heated roller fixing methods have been adopted. In this method, the toner image on the sheet to be fixed is brought into pressure contact with the surface of a heated roller whose surface is coated with a material that has releasability to the toner, while fixing is performed. This method has extremely good thermal efficiency when fixing the toner image, which makes high-speed copying possible. However, on the other hand, since the roller surface and the toner image contact each other in a heated molten state, the toner image A portion of the toner remains on the roller surface, and this remaining toner image is likely to be transferred onto the next sheet to be fixed, resulting in so-called ghost images and stains. This undesirable phenomenon is called an offset phenomenon.

The present invention relates to improvements to the previously proposed dry toner, and proposes a new dry toner that has improved anti-offset properties in addition to the plasticizer resistance and moisture absorption resistance.

The present invention provides a toner in which styrene or a derivative thereof is added to a polymerizable unsaturated precursor resin obtained by reacting an epoxy resin, a polymerizable unsaturated carboxylic acid, and a release compound having a functional group that can react with the epoxy group. An object of the present invention is to provide a dry toner for electrophotography containing, as a binder component, a resin obtained by copolymerizing one or more polymerizable monomers containing the following.

By using the toner according to the present invention, it is possible to prevent the offset phenomenon during heating roller fixation, and it is also possible to obtain a toner image with excellent plasticizer resistance, and at the same time, the toner in the copying machine is charged Image deterioration can be prevented without deterioration of characteristics.

As the Epoquin resin, various commercially available epoxy resins can be used, such as bisphenol A glycidyl ether type, novolak glycidyl ether type, halogenated bisphenol A glycidyl ether type, hydrogenated bisphenol A glycidyl ether type, bisphenol F glycidyl ether type, etc. Various types of aromatic and aliphatic cyclic epoxy resins and mixtures thereof can be used. Among these epoxy resins, those having a melting point of 20° C. or higher (Durran mercury method) are preferred, and those having a melting point of 50° C. or higher are more preferred. If the melting point is less than 20° C., the toner will have insufficient plasticizer resistance and will tend to cause an offset phenomenon when fixedly attached to a heating roller, reducing the effects of the present invention.

Examples of the polymerizable unsaturated carboxylic acids include olefin monocarboxylic acids, acetylene monocarboxylic acids, highly unsaturated monocarboxylic acids, and halogen-substituted products thereof, unsaturated dicarboxylic acids, unsaturated polycarboxylic acids, and halogen-substituted products thereof. monoalkyl esters of unsaturated dicarboxylic acids, etc. can be used. Considering the esterification reactivity with the epoxy resin and the copolymerization reactivity with the polymerizable monomer, the polymerizable unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, maleic acid, and maleic anhydride. The acids fumaric acid, itaconic acid, and maleic acid monoalkyl esters, fumaric acid monoalkyl esters, itaconic acid monoalkyl esters are preferred.

In addition, the reaction ratio of the epoxy resin and the polymerizable unsaturated carboxylic acid is determined based on the need to prevent a moderate increase in molecular weight while maintaining good reactivity with the polymerizable monomer, relative to 1 g equivalent of the epoxy resin. Therefore, it is preferable that the amount of the polymerizable unsaturated carboxylic acid is 0.05 to 1.0 mol.

Examples of the releasing compound having a functional group capable of reacting with the epoxy resin include a wax containing a carboxyl group, an organopolysiloxane containing a carboxyl group or an amine group, and preferably dimethylpolysiloxane.

As a wax containing a carboxyl group, Wile
Encyclopedia published by yand Sona
of PolymerScience and Te
Among the various waxes described in Chnology Volume 14, pages 768 to 779, waxes having a cargoxyl group can be used. Those having a melting point of 70° to 150°C are preferred, and those having a melting point of 90° to 150°C are particularly preferred. As such wax,
Product name: Cardia 320 manufactured by Western Chemical Company
”, product name “Litene OX” manufactured by Uipco Chemical Co., Ltd.
-88”, Petrolite product name “Petronau
ba C”, Hoechst product name “Hoechst Wax S”
”, “Hoechst Wax L”, “Hoechst Wax LP
”, “Hoechst Wax OM”, “Hoechst Wax F
Mineral waxes such as "L", "Hoechstwax
Sashiwax E-300”, BASF product name “GA”
Examples include polyethylene waxes such as ``Mitsui Hiwax 4053'' manufactured by Mitsui Petrochemicals Co., Ltd. and ``Mitsui Hiwax 4053'' manufactured by Mitsui Petrochemicals. On the other hand, an example of the organopolysiloxane having a carboxyl group is "Toray Silicone SF8418" manufactured by Toray Industries, Inc., and an example of an organopolysiloxane having an amino group is "Toray Silicone SF8417" manufactured by Toray Industries. The amount of the wax and organopolysiloxane used can be 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the binder resin component of the toner.

If less than 0.1 part by weight is used, the offset resistance of the toner will decrease, and if it exceeds 20 parts by weight, the fluidity of the toner will decrease.
Increased fog on copy paper is likely to occur. It is known that anti-offset properties can be improved by adding and mixing a releasing compound such as wax or organopolysiloxane into the binder resin of a toner, but all of these releasing compounds are not compatible with the binder resin. It has poor solubility and is difficult to disperse finely and uniformly.

When such a compound is added in an amount effective to prevent the offset phenomenon, there is a drawback that the fluidity of the toner in a copying machine is deteriorated. In the present invention, by directly introducing such a mold-releasing compound into the binder resin molecule through chemical bonding, offset resistance is improved without the above-mentioned drawbacks.

The reaction between the above-mentioned epoxy resin, polymerizable unsaturated carboxylic acid, and a mold-releasing compound having a functional group capable of reacting with an epoxy group is carried out with or without using a suitable reaction solvent,
If necessary, a reaction catalyst such as tertiary amines, quaternary ammonium compounds, imidazoles, fatty acid metal salts, etc. may be used. The reaction temperature must be high enough for the reaction to occur, and must be kept so that side reactions other than the desired reaction, such as the reaction of an epoxy group with a carboxyl group or an amino group, do not occur, and is usually 20°C to A temperature range of 150°C is preferred.

The polymerizable monomer contains styrene or a derivative thereof as an essential component, and further contains other polymerizable monomers copolymerizable with these, if necessary. As the styrene derivative, for example, vinyltoluene, p-chlorostyrene, etc. can be used. Other polymerizable monomers that may be used as necessary include vinylnaphthalene, ethylenically unsaturated monoolefins such as ethylene, propylene, and butylene, vinyl chloride, vinyl acetate, and vinyl benzoate. Vinyl esters, ethylenic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, and n-butyl methacrylate, ethylenic monocarboxylic acid nitriles such as acrylonitrile, methacrylonitrile, and acrylamide. Alternatively, examples thereof include amides, diesters of ethylenic dicarboxylic acids such as dimethyl maleate, dibutyl maleate, and dibutyl maleate, as well as vinyl ketones, vinyl ethers, vinylidene halides, and N-vinyl compounds.

The content of styrene or its derivatives contained as an essential component in the polymerizable monomer used in the present invention is 50% of the polymerizable monomer (excluding the polymerizable unsaturated esterified product).
The above is preferable. The content of styrene or its derivatives is 5
If it is less than 0% by weight, the pulverizability and moisture resistance of the toner tend to decrease.

The reaction ratio of the polymerizable unsaturated precursor resin obtained by reacting the epoxy resin, the polymerizable unsaturated carboxylic acid, and the mold release compound to the polymerizable monomer is 1/9 on a weight basis.
~9/1 is preferred. If this ratio is less than 1/9,
Good plasticizer resistance of epoxy resin is not exhibited, 9/1
If it is larger, the hygroscopicity of the toner tends to increase. The above-mentioned copolymerization of the polymerizable unsaturated precursor resin and the polymerizable monomer is carried out by an addition polymerization reaction. This includes polymerization methods. The resin thus obtained has a softening point of 80°C to 170°C and a temperature of 5.0°C.
Resins having a weight average molecular weight of 00 to 300,000 can be suitably used, with a softening point of 90 to 150 °C and a
Resins having a weight average molecular weight of 00 to 150,000 can be particularly preferably used.

The toner according to the present invention is produced by appropriately mixing the resin obtained as described above with coloring agents such as dyes and pigments, auxiliary agents such as charge control agents, waxes, etc. that are conventionally used in electrophotographic toners. It can be produced by kneading, pulverizing, and classifying these by known methods.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples. In addition, unless otherwise specified, "parts" in the examples mean "parts by weight."

Example 1 600 parts of Epicoat 1004 (epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.), 450 parts of xylene, and 150 parts of n-butanol were heated and mixed at about 150°C in a 3-liter glass flask, and polyethylene wax (Mitsui High 50 parts of wax 4053E, oxidized 25) and 10 parts of maleic acid monobutyl ester were added and kept at the same temperature for about 3 hours. After confirming that the acid value of the solution was 1 or less, the solution temperature was lowered to 120°C, and styrene 3 was added to the above reactant.
A mixture of 00 parts of azobisisobutyronitrile and 10 parts of azobisisobutyronitrile was added dropwise thereto, and the mixture was polymerized for about 6 hours. From this reactant, temperature 1
Xylene and n-butanol were distilled off under conditions of 70° C. and 30 mmHg to obtain a resin having a softening point (ring and ball method) of 160° C. and a weight average molecular weight of about 40,000. 86 parts of this resin, 10 parts of carbon black "ELF 8" (carbon black manufactured by Cabot Corporation), and 2 parts of "Oil Black BW" (charge control agent manufactured by Orient Chemical Co., Ltd.) were mixed, kneaded with hot rolls, cooled, and then pulverized. The toner was classified into a toner having an average particle size of about 9 to 13 microns, and this was used as a sample. 4 parts of this toner are mixed with 96 parts of iron powder Chiaria having an average particle size of about 50 to 80 microns to form a developer, which is used to print a 3 cm wide unfixed peta black on copy paper by conventional electrophotography. An image was formed, and then the copy paper was passed between a pair of rollers of a heated roller fixing device to fix the image, and it was investigated whether an offset phenomenon occurred during this process.

The fixing device used in this test consisted of a heated roller with a surface layer of polytetrafluoroethylene and silicone rubber (HTV).
It has a pair of pressure rollers with a surface layer of silicone), and the contact pressure of this pair of rollers is 15kg-350m.
m, the circumferential rotational speed was set to 165 mm/sec, and the surface temperature of the heating roller was set to various temperatures in the range of 160°C to 220°C. In addition, use paper of a size that has one side longer than the circumference of the roller as the copy paper, position the solid black image at the leading edge of the paper, and if an offset phenomenon occurs, it is It is now recognized at the end of the paper.

In this test, the toner did not cause an offset phenomenon;
It was also confirmed that it could be completely fixed.

Next, using the developer described above, a toner image of a standard test pattern is formed on a copy paper by a normal electrophotographic method.
Fixing was carried out with a heated roller having a surface temperature of 60°C.

The above image was adhered to a transparent polyvinyl chloride sheet containing 50% by weight of plasticizer (dioctyl phthalate), a square wooden board 1 mm thick and 5 cm on a side was placed on top of it, and a 2 kg sheet was placed on top of it. The state of toner transfer to the polyvinyl chloride sheet was examined after a certain period of time after a weight was placed on the sheet. The toner of this example did not show any transfer to the polyvinyl chloride sheet even after 60 days, and there was no bleeding or staining of the copied image. Further, about 1 g of the resin, which is the binder component of the toner, was immersed in 20 cc of dioctyl phthalate, but no change was observed even after 14 days. Furthermore, changes over time in the amount of charge of this toner were investigated. The developer was placed on a pole mill stand for 6 minutes.
Stir at a constant rotational speed for 0 minutes to obtain a charge amount Q60 (μq/g
) was measured. After leaving this sample for 6 days, the amount of charge Q
(μq/g) was measured. Attenuation rate of charge amount (Q/Q60
)×100 is 85 to 95%, which is similar to the behavior seen in ordinary toner and can be said to be at a level that does not pose any practical problem.

On the other hand, the moisture absorption rate of the above toner was 0.09%. The term "moisture absorption rate" refers to the drying of bg toner at a temperature of 50°C, a degree of vacuum of 5mm/Hg, and a time of 3 hours at a relative humidity of 80%.
It is defined as 100 (ba)/a (%), where ag is the weight of this toner after being left in a room temperature atmosphere for 24 hours. The term hygroscopicity mentioned below also follows this definition.

Comparative Example 1 A toner was prepared and tested in the same manner as in Example 1, except that "Mitsui Hiwax 4053E" in Example 1 was not used. As a result, no transfer of toner to the polyvinyl chloride sheet was observed, and the resin itself was not bath-dissolved in dioctyl phthalate at all. Furthermore, the moisture absorption rate of the toner is 0.13 to 0.08%, and the charge amount decay rate (Q/Q60)
×100 was 85-95%, but in the fixation test it was 16%.
An offset phenomenon occurred at 0°C.

Comparative Example 2 300 parts of water containing 5% by weight of calcium phosphate was placed in a separable flask with a volume of 1 liter, and 8 parts of styrene was placed in it.
0 parts, 20 parts of n-butyl acrylate, 1 part of azobisisobutyronitrile, and 3 parts of divinylbenzene were added and stirred.
Polymerization was carried out for 8 hours while heating to 80°C. After the polymerization was completed, the suspension was cooled and taken out, centrifugally dehydrated, washed, and dried to obtain bead-shaped resin. 86 parts of this resin, 10 parts of carbon black "Elf 8", 2 parts of "Oil Black BW",
Example 1 using 5 parts of “Mitsui Hiwax 4053B”
A toner and a developer were prepared and tested in the same manner as described above. The moisture absorption rate of this toner was 0.001 to 0.06%, and the charge attenuation rate (Q/Q60)×100 was 98%, so there were no problems. In addition, the temperature of the heating roller was set to 2 in the fixing test.
No offset phenomenon was observed even when the temperature was raised to 20°C. However, the stiff resin itself easily dissolves in dioctyl phthalate, and in a pressure bond test with a polyvinyl chloride sheet, a standard test pattern was transferred onto the sheet.
Some of the images also peeled off.

Example 2 A synthetic resin with a softening point (ring and ball method) of 163°C and a weight average molecular weight of about 43,000 was produced in exactly the same manner as in Example 1 except that "Hoechstwax S" was used instead of "Mitsui Hiwax 4053E" in Example 1. A resin was obtained and tested in the same manner as in Example 1.

Practical Example 3 In Example 1, 480 parts of "Epicoat 1004" and "Epicoat 828" (epoxy resin manufactured by Yuka Ciel Epoxy Co., Ltd.) 12
A resin having a softening point (ring and ball method) of 150° C. and a weight average molecular weight of about 38,000 was obtained by the same synthetic method except that 0 parts of the mixture was used, and the same tests as in Example 1 were conducted.

Example 4 Same as Example 1 except that a mixture of 225 parts of styrene and 75 parts of 2-ethylhexyl acrylate was used instead of 300 parts of styrene, but the softening point (ring and ball method) was 1.
A resin having a weight average molecular weight of about 10,000 was obtained at 53° C. and tested in the same manner as in Example 1.

Example 5 In Example 1, maleic acid monobutyl ester 10
A resin having a softening point (ring and ball method) of 165° C. and a weight average molecular weight of about 45,000 was obtained in the same manner as in Example 1, except that the part was changed to 15.5 parts.

Example 6 In Example 1, 5 parts of acrylic acid was used instead of 10 parts of maleic acid monobutyl ester, and 0.01 part of hydroquinone monomethyl ether and 0.3 part of 2-methylimidazole were newly added to produce "Epicote 1004". and acrylic acid in exactly the same manner except that the reaction temperature was 100°C, the softening point (ring and ball method) was 166°C, and the weight average molecular weight was about 450.
00 resin was obtained and tested in the same manner as in Example 1.

Example 7 A resin having a softening point (ring and ball method) of 170°C and a weight average molecular weight of about 42,000 was obtained in the same manner as in Example 1, except that 600 parts of styrene was changed from 300 parts. The test was conducted on

The test results of Examples 2 to 7 above are combined with Example 1 and Comparative Example 1.
and Comparative Example 2 are summarized in Table 1.

Claims (6)

[Claims] 1. One or more types of polymerization containing styrene or its derivatives in a polymerizable unsaturated precursor resin obtained by reacting an epoxy resin, a polymerizable unsaturated carboxylic acid, and a mold release compound having a functional group that can react with an epoxy group. 1. A dry toner for electrophotography, characterized in that it contains a resin obtained by copolymerizing a monomer as a binder component. 2. 2. The toner according to claim 1, wherein a wax or organopolysiloxane having a carboxyl group or an amino group is used as the releasing compound having a functional group capable of reacting with the epoxy group. 3. 2. The toner according to claim 1, wherein the content of styrene or its derivative in the polymerizable monomer is 50% or more of the total weight of the polymerizable monomer. 4. 2. The toner according to claim 1, wherein the epoxy resin is an epoxy resin having a melting point determined by the Durand mercury method of 20° C. or higher. 5. 2. The toner according to claim 1, wherein the reaction ratio of the polymerizable unsaturated precursor resin to the polymerizable monomer is within the range of 1/9 to 9/1 on a weight basis. 6. 2. The toner according to claim 1, wherein the binder component resin is a resin having a softening point (ring and ball method) of 80° C. to 170° C. and a weight average molecular weight of 5,000 to 300,000.