JP3393085B2 - Electrophotographic toner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner used in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art An electrostatic charge image formed on an electrostatic charge image support in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc., uses toner particles in which a colorant is dispersed in a resin. To be visualized. This visualized image is fixed as it is on the electrostatic image support, or transferred to another support and then fixed. As a heating and fixing method for a toner image, there are a non-contact heating method such as oven fixing and a contact heating method by heat roller fixing. In recent years, low energy fixing and high speed fixing process are required, and the latter method is mainly used because of advantages such as high heat efficiency, low power consumption, fixing, and downsizing of an apparatus. . However, this method has a problem that an offset phenomenon occurs. The offset phenomenon is that a part of the toner forming an image at the time of fixing is transferred to the surface of the heat roller, and this is transferred onto the transfer paper which is sent next to stain the image. Further, when the glass transition temperature is lowered for low-temperature fixing, there is a problem of blocking that powdery toner is fused during storage. That is, at present, it is possible to fix at low temperature,
There is a demand for an electrophotographic toner having excellent offset resistance and storage stability, and various proposals have been made in the prior art and put to practical use in order to satisfy these requirements.

One of them is an attempt to achieve low temperature fixing by lowering the molecular weight of the binder resin mixed in the toner. But,
In the conventional toner using a vinyl resin such as styrene resin and acrylic resin, the toner becomes brittle due to the low molecular weight, and the stress in the developing machine causes the toner to be crushed, fused to the carrier and the sleeve, and the long-term Image deterioration due to changes in charging characteristics was inevitable due to use.

On the other hand, when the molecular weight of a condensation resin represented by a polyester resin is lowered, the melting point is lowered, but the viscosity is also lowered at the same time, causing a problem that an offset phenomenon occurs on the fixing roll. In order to prevent this, the introduction of a crosslinked structure for broadening the molecular weight distribution of the polyester resin has been introduced. However, in this method, although the molecular weight distribution is widened by the crosslinking and the offset phenomenon is suppressed, there is a problem that the low temperature fixing property is deteriorated because the entire molecular weight becomes high. Therefore, the glass transition temperature of the resin (hereinafter referred to as Tg) is required for low temperature fixing.
Therefore, the storage stability could not be satisfied because blocking occurred during storage because the storage capacity had to be lowered. As described above, the toner according to the related art cannot achieve low-temperature fixability at the same time while satisfying offset resistance and storage stability.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a novel electrophotographic toner which has solved the above-mentioned problems with the prior art toners.
Another object of the present invention is to provide an energy-saving type electrophotographic toner suitable for a heat fixing system.

[0006]

The electrophotographic toner of the present invention is as described below. The invention of claim 1 is
A polymer having a carbodiimide group represented by the following formula in its molecule.
A polyester resin having a crosslinked structure by reaction with Li carbodiimide resin, ester waxes, polyethylene
, Fischer-Tropsch wax, α-olefin
Maleic anhydride and / or maleic anhydride ester copolymer
An electrophotographic toner containing at least one low melting point compound selected from coalesce, oxidized polyethylene wax, petroleum wax, and thermoplastic resin having a melting start temperature of 60 to 100 ° C.

## STR1 ##-N = C = N-

The invention of claim 2 is the toner for electrophotography according to claim 1, wherein the compounding amount of the low melting point compound is 1 to 40 parts by weight with respect to 100 parts by weight of the polyester resin. In the invention of claim 3, the thermoplastic resin is geo
Linear poly (ether) synthesized from carboxylic acid and / or dicarboxylic acid
The battery according to claim 1, which is a stell resin.
It is a toner for child photography.

[0008]

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The toner for electrophotography of the present invention uses a polyester resin having a crosslinked structure by a reaction with a polycarbodiimide resin having a carbodiimide group in the molecule. The polyester resin contains at least a divalent alcohol component and a divalent carboxylic acid component. An acid or an acid anhydride thereof or a lower alkyl ester component thereof, and optionally a polyhydric alcohol component having a valence of 3 or more and a polyvalent carboxylic acid having a valence of 3 or more, or an acid anhydride thereof or a lower alkyl ester component thereof. It is characterized by comprising at least one type of

Used in the polyester resin of the present invention,
Examples of the divalent alcohol component include the following.
That is, diethanolamine, ethylene glycol,
Diethylene glycol, propylene glycol, isoprene glycol, octane diol, 2,2-diethyl-1,3-propane diol, spiro glycol, neopentyl glycol, 1,3-butane diol, 1,4
-Butanediol, 2-butyl-2-ethyl-1,3-
Propanediol, 1,6-hexanediol, hexylene glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, hydrobenzoin, bis (β-hydroxyethyl) terephthalate, bis (hydroxybutyl) terephthalate , Polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A, polyoxyethylenated biphenol, polyoxypropyleneated biphenol, and the like.

Examples of the divalent carboxylic acid component include fumaric acid, maleic acid, succinic acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid. Acid, adipic acid, sebacic acid,
Dodecanedioic acid, 1,12-dodecanedicarboxylic acid, eicosanedioic acid, azelaic acid, brassic acid, naphthalenedicarboxylic acid, biphenyl-4,4'-dicarboxylic acid,
2,3-piperazine-dicarboxylic acid, iminodicarboxylic acid, imidazole-4,5-dicarboxylic acid, piperidine-dicarboxylic acid, pyrazoledicarboxylic acid, N-methylpyrazoledicarboxylic acid, N-phenylpyrazoledicarboxylic acid, pyridinedicarboxylic acid, carbazole -3
6-dicarboxylic acid, 9-methylcarbazole-3,6-
Examples thereof include dicarboxylic acid, carbazole-3,6-dibutyric acid, carbazole-3,6-γ, γ′-diketobutyric acid, acid anhydrides thereof and lower alkyl esters thereof.

As the polyhydric alcohol component having 3 or more valences,
Sorbitol, 1,2,3,6-hexanetetrol,
1,2,6-hexanetriol, 1,4-sorbitan, pentaerythritol, dipentaerythritol,
Tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol,
2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-
Examples include trihydroxybenzene and the like.

Examples of the trivalent or higher carboxylic acid component include trimellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,5,5.
7-naphthalene tricarboxylic acid, pyridine tricarboxylic acid, pyridine-2,3,4,6-tetracarboxylic acid,
Examples are 1,2,7,8-tetracarboxylic acid, butanetetracarboxylic acid, and the like, and acid anhydrides thereof and lower alkyl esters thereof can be used.

[0014] The polycarbodiimide trees to be used in the present invention
The fat has a carbodiimide group in the molecule and forms a carbamoylamide bond by reaction with the carboxyl group of the polyester resin and an isourea bond by reaction with the hydroxyl group of the polyester resin.
The polycarbodiimide resin, which is a carbodiimide compound used in the present invention, is prepared by converting the raw material isocyanate compound into 3-methyl-1-phenyl-2-phosphoren oxide, 1-phenyl-2-phosphoren-1.
In the presence of a carbodiimidization catalyst such as -oxide
It can be obtained by a decarboxylation condensation reaction at a reaction temperature of up to 150 ° C. under pressure or in a solvent such as an aliphatic acetate type, a halogen type or an alicyclic ether.

As the isocyanate compound as a raw material for producing the polycarbodiimide resin, n-butyl isocyanate, tert-butyl diisocyanate, i
so-butyl isocyanate, ethyl isocyanate,
n-propyl isocyanate, iso-propyl isocyanate, cyclohexyl isocyanate, n-octadecyl isocyanate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, o-tolidine diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4 ′ -Dicyclohexylmethane diisocyanate, 4,4′-diphenyl ether diisocyanate, 3,3′-dimethoxy-4,4′-biphenyl diisocyanate, p-phenylene diisocyanate, naphthylene-1,5-diisocyanate, m-xylylene diisocyanate, hydrogenation Xylylene diisocyanate, m-tetramethyl xylylene diisocyanate, p-tetramethyl xylylene diisocyanate, hexamethylene diiso Aneto, trimethylhexamethylene diisocyanate, can be mentioned isophorone diisocyanate.

Examples of the polycarbodiimide resin obtained from the above raw materials include polytert-butylcarbodiimide, polytetramethylxylylenecarbodiimide, poly2,4-toluylenecarbodiimide, poly2,6-toluylenecarbodiimide and polyo-tolidine. Carbodiimide, poly 4,4'-diphenylmethane carbodiimide,
Poly 4,4'-dicyclohexylmethane carbodiimide, poly 4,4'-diphenyl ether carbodiimide, poly 3,3'-dimethoxy-4,4'-biphenyl carbodiimide, poly p-phenylene carbodiimide,
Examples thereof include polynaphthylene-1,5-carbodiimide, polym-xylylenecarbodiimide, polyhydrogenated xylylenecarbodiimide, polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, and polyisophoronecarbodiimide.

[0017] Low-melting compounds used in the present invention, Este
Wax, polyethylene, Fischer Tropsi
Wax, α-olefin maleic anhydride and / or none
Water maleic acid ester copolymer, polyethylene oxide
Gas, petroleum wax, and melting start temperature of 60 to 10
At least one selected from thermoplastic resins having a temperature of 0 ° C.
It Melting initiation temperature, Ru descent temperature der of at plunger to the measuring instrument and measurement conditions below.

Measuring instrument: Shimadzu's advanced flow tester CF-500 Measuring conditions: Plunger: 1 cm ² Die diameter: 1 mm Die length: 1 mm Load: 20 kgF Preheating temperature: 50-80 ° C Preheating time: 300 sec Temperature rising rate: 6 ° C / min

[0019] Low-melting compounds used in the present invention, as the ester-based wax, carnauba wax, rice wax, candelilla wax, Japan wax, jojoba oil,
Beeswax, lanolin, montan wax, ozokerite,
Ceresin, hardened soybean oil, rapeseed hardened oil, castor hardened oil and the like, et al are further polyethylene, Fischer-Tropsch wax, alpha olefin maleic anhydride and / or maleic acid ester copolymer, polyethylene wax oxide
And a petroleum wax such as paraffin wax, microwax, and petrolatum. Other thermosetting resins have a melting start temperature of 60.
The temperature is not particularly limited as long as it is -100 ° C, but examples thereof include resins such as linear polyester resins, non-linear polyester resins, styrene-acrylic resins, polyamide resins, and polyimide resins. Since the fixing strength is improved with the decrease in the viscosity of the toner, the low melting point compound in the present invention includes, among others, an ester wax , an α- olefin maleic anhydride and / or a maleic anhydride ester copolymer, and a line. Polyester resins are preferred.

<Method for Synthesizing Polyester Resin and Linear Polyester Resin> The polyester resin used in the present invention requires a divalent alcohol component and a divalent carboxylic acid or its acid anhydride or its lower alkyl ester component. According to the above, polyhydric alcohols with 3 or more valences and polycarboxylic acids with 3 or more valences or their acid anhydrides or their lower alkyl ester components are placed in a 4-neck round bottom flask equipped with a stirrer, a condenser and a nitrogen gas introduction tube. It is obtained by conducting a polycondensation reaction at a temperature of 180 to 260 ° C. while introducing nitrogen gas. 10 mm inside the reaction system if necessary
The pressure may be reduced under a vacuum of Hg or less to accelerate the reaction. During the reaction, an esterification catalyst such as zinc oxide, dibutyltin oxide, tetrabutoxytitanate, p-toluenesulfonic acid or the like may be used. The linear polyester resin, which is a low-melting compound, is composed of the above divalent alcohol component and a divalent carboxylic acid or its acid anhydride or its lower alkyl ester component. can get.

The polyester resin other than the linear polyester resin of the low melting point compound used in the present invention has a glass transition temperature of 50 ° C. or higher, preferably 50 ° C. or higher and 80 ° C. or lower, as measured by a differential scanning calorimeter (DSC). The melting start temperature measured under the same conditions as the melting start temperature of the low melting point compound is 70 ° C. or higher, preferably 80 ° C. or higher 12
0 ° C. or lower and a flow softening point of 100 ° C. or higher, preferably 100 ° C. or higher and 150 ° C. or lower, and more preferably 105.
The temperature is not less than ℃ and not more than 130 ℃.

The flow softening point refers to the midpoint temperature from the temperature when the plunger starts to drop to the temperature when it ends.

<Reaction of Polycarbodiimide Resin with Polyester Resin> Polycarbodiimide resin reacts with an active hydrogen group,
In the polyester resin, a carbamoylamide bond can be formed by a reaction with a carboxyl group, and an isourea bond can be formed by a reaction with a hydroxyl group to crosslink the resin. In this case, the acid value and the hydroxyl value in the polyester resin are 3 m.
It is preferably gKOH / g or more and 100 mgKOH / g or less. More preferably, 5 mgKOH / g or more 6
It is 0 mgKOH / g or less. Acid value and hydroxyl value are 3m
If it is smaller than gKOH / g, the crosslinking reaction with the polycarbodiimide resin becomes insufficient, and the offset resistance at high temperature as a toner cannot be obtained, which is not preferable. Conversely 10
When it exceeds 0 mgKOH / g, the crosslink density becomes too high and the fixing strength is deteriorated, and moreover, the functional groups in the resin increase, so that the charging property becomes unstable, which is not preferable. The addition amount of the polycarbodiimide resin, relative to 100 parts by weight of the polyester resin is preferably 50 parts by weight 0.1 parts by weight. More preferably, from 0.5 parts by weight to 3
It is 0 part by weight, most preferably 1 part by weight to 20 parts by weight. If the addition amount of the polycarbodiimide resin is less than 0.1 parts by weight, the crosslinking reaction by the polycarbodiimide resin will be insufficient and the toner will not have high-temperature offset resistance. On the contrary, if the amount is more than 50 parts by weight, the offset resistance is improved, but the melt viscosity after the crosslinking reaction becomes too high, and the fixing strength as a toner is deteriorated, which is not preferable.

[0024] The method of adding the <carbodiimide crosslinking method and the low-melting compound added pressure method> crosslinking method and the low-melting-point compounds of a polyester resin having a crosslinked structure by reaction with the polycarbodiimide resin used in the present invention, for example, a polyester resin In the four-necked flask used in the synthesis of, the polyester resin synthesis monomer is added at the same time, after the polyester resin synthesis is added later, or the synthesized polyester resin and colorant and other additives are superposed. It is possible to obtain a kneaded product by adding it in a toner forming step of mixing with a mixer or the like and performing hot melt kneading in a kneader.

The obtained kneaded product is pulverized by a jet mill and then classified by a dry airflow classifier to obtain an electrophotographic toner as it is. Examples of the melt-kneader used for melt-kneading include a single-screw extrusion kneader, a twin-screw extrusion kneader, an extruder, a roller mixer, a Banbury mixer, and a pressure kneader. Further, as the resin used in the present invention, a polyester resin is desirable, but with a reaction with a polycarbodiimide resin , a carboxyl group, a hydroxyl group, as long as it has an active hydrogen group such as an amino group, other polymerizable monomers It may be copolymerized, or can be used as a mixture with another resin. Examples of other resins include polyether polyol, acrylic polyol, epoxy polyol, polyacrylic acid, polyamide resin, styrene resin, styrene-acrylic copolymer resin, polyester resin, polyethylene resin, epoxy resin, silicone resin. Resins such as resins and polyurethane resins may be blended.

The electrophotographic toner of the present invention may contain various colorants and magnetic substances in addition to the above resin components. The colorant used in the present invention, carbon black, aniline blue, phthalocyanine blue, quinoline yellow, malachite green, lamp black,
Rhodamine-B, quinacridone, etc. are mentioned. The amount of the colorant added is 1 to 20% by weight based on the resin component.
As the charge control agent, for positively charged toner, nigrosine dye, ammonium salt, pyridinium salt, azine, etc. are added in an amount of 0.1 to 10% by weight based on the resin component. A toner using a polyester resin generally gives a negative charging property, but when a charge control agent for a negative charging toner is added if necessary, a chromium complex, an iron complex or the like is used. When the negative chargeability is too strong, it is possible to control the neutralization by adding the positive charge control agent.

As the magnetic substance used in the electrophotographic toner of the present invention, ferrite, magnetite or other iron, cobalt, nickel or other ferromagnetism metals or alloys, compounds containing these elements, or ferromagnetism are used. An alloy which does not contain an element but exhibits ferromagnetism when subjected to an appropriate heat treatment, for example, an alloy of a type called Heusler alloy containing manganese and copper such as manganese-copper-aluminum and manganese-copper-tin, or , Chromium dioxide, and others. These magnetic materials are uniformly dispersed in the resin component in the form of fine powder having an average particle size of 0.1 to 1 micron. The content of toner 1 is
20 to 70 parts by weight, preferably 40 to 100 parts by weight
70 parts by weight.

[0028]

EXAMPLES The present invention will be described in more detail with reference to synthetic examples of resins used in the present invention and examples of the present invention, but the present invention is not limited to these examples.

(Synthesis of Polyester Resin) (Synthesis Example 1) Polyoxyethylenated bisphenol A2
52.8 g (0.8 mol), polyoxypropyleneized bisphenol A 68.8 g (0.2 mol), terephthalic acid 66.5 g (0.4 mol), isophthalic acid 66.5 g
(0.4 mol), 23 g of trimellitic anhydride (0.12
Mol) and 0.05 g of dibutyltin oxide made of glass 1
Put in a 4-liter 4-necked flask, thermometer, stirrer,
A downflow condenser and a nitrogen introduction tube were attached, and the reaction was performed for 6 hours under a nitrogen stream at a reaction temperature of 180 to 220 ° C. with a mantle heater. After the end of the methanol outflow,
While maintaining the temperature at 220 ° C., the pressure inside the reactor was reduced to 10 Torr or less, and after reacting for 1 hour, a polyester resin A was obtained. The obtained resin A had a DSC Tg of 62 ° C., a flow tester melting start temperature of 102 ° C., and a flow softening point of 12
It was 8 ° C. The acid value was 18 mgKOH / g and the hydroxyl value was 25 mgKOH / g.

(Synthesis of Polyester Resin Containing Carbodiimide Cross-Linked Structure) (Synthesis Example 2) Polycarbodiimide resin (product name: Carbodilite HMV-10 manufactured by Nisshinbo Co., Ltd.) at the time of charging the monomer in Synthesis Example 1
A carbodiimide crosslinked structure-containing polyester resin B was obtained by the same operation as in Synthesis Example 1, except that 5 parts by weight of B) was added and synthesized. The resin B thus obtained had a Tg of 63 ° C., a melting start temperature of 108 ° C., and a flow softening point of 138 ° C.

<Synthesis of Linear Polyester Resin> (Synthesis Example 3) A linear polyester resin C having a low melting point compound was obtained by the same method as in Synthesis Example 1 except that trimellitic anhydride was removed from Synthesis Example 1. . The resulting resin C has a Tg of 60 ° C, a melting start temperature of 85 ° C, and a flow softening point of 98 ° C.
Met.

<Synthesis of Polyester Resin Containing Carbodiimide Crosslinked Structure and Low Melting Point Compound> (Synthesis Example 4) In the synthesis of the polyester resin of Synthesis Example 1, the linear resin C obtained in Synthesis Example 3 before the depressurizing step was performed. 1
A low-melting-point compound-containing polyester resin D was obtained by adding 0 parts by weight, and the obtained resin D had a Tg of 60 ° C., a melting start temperature of 96 ° C., and a flow softening point of 124 ° C.

(Synthesis Example 5) When the carbodiimide crosslinked structure-containing polyester resin of Synthesis Example 2 was synthesized, 1.0 part by weight of the linear resin C obtained in Synthesis Example 3 was added before the depressurizing step. Then, a polyester resin E containing a carbodiimide crosslinked structure and containing a low melting point compound was obtained. Resin E obtained
Had a Tg of 63 ° C, a melting start temperature of 105 ° C, and a flow softening point of 132 ° C.

(Manufacture of Toner) (Example 1) Resin A of Synthesis Example 1 50 parts by weight Polycarbodiimide resin 5 parts by weight (trade name: Carbodilite HMV-8CA manufactured by Nisshinbo Industries Inc.) Linear polyester resin C of Synthesis Example 3 20 parts by weight carbon black (manufactured by Mitsubishi Chemical Co., Ltd .: MA-100) 5 parts by weight chrome-based salt dye (trade name: TRH, manufactured by Hodogaya Chemical Co., Ltd.) 2 parts by weight low molecular weight polypropylene (manufactured by Sanyo Chemical Co., Ltd.) Name: Biscol 2 parts by weight 330P) The mixture having the above composition was dry-blended with a super mixer and subjected to hot melt kneading at a kneading temperature of 120 ° C. to obtain a kneaded product. After cooling the kneaded material, pulverization and classification are performed,
Negatively charged toner particles having an average particle diameter of 10 μm were obtained. 0.5 parts by weight of hydrophobic colloidal silica was externally added to 100 parts by weight of the toner particles by a Henschel mixer,
An electrophotographic toner of the present invention was obtained. D of the obtained toner
The Tg by SC was 63 ° C, the melting start temperature by the flow tester was 100 ° C, and the flow softening point was 129 ° C.

(Example 2) Carnauba wax (trade name of Noda Wax Co., Ltd.) was added to 20 parts by weight of the linear resin C of Example 1.
Carnauba wax No. 1) The same operation as in Example 1 was carried out except that the amount was changed to 5 parts by weight to obtain an electrophotographic toner of the present invention. The obtained toner had a Tg of 63 ° C., a melting start temperature of 97 ° C., and a flow softening point of 129 ° C.

Example 3 20 parts by weight of the linear resin C of Example 1 was used as an α-olefin maleic anhydride copolymer (trade name: PA-30, manufactured by Mitsubishi Chemical Corporation, melting start temperature: 73.6 ° C.).
The same operation as in Example 1 was carried out except that the amount was changed to 10 parts by weight to obtain an electrophotographic toner of the present invention. The obtained toner had a Tg of 62 ° C., a melting start temperature of 98 ° C., and a flow softening point of 127 ° C.

Example 4 The same operation as in Example 1 except that 20 parts by weight of the linear resin C of Example 1 was changed to 5 parts by weight of oxidized polyethylene wax (trade name: Hiwax 4202E manufactured by Mitsui Chemicals, Inc.). Then, the electrophotographic toner of the present invention was obtained. The Tg of the obtained toner was 64 ° C., the melting start temperature was 103 ° C., and the flow softening point was 130 ° C.

(Example 5) Resin B of Synthesis Example 2 50 parts by weight Resin C of Synthesis Example 3 20 parts by weight Carbon black (trade name: MA-600 manufactured by Mitsubishi Chemical Corporation) 5 parts by weight Chromium-based salt dye (Orient) Chemical company product name: Bontron 2 parts by weight S-44) Low molecular weight polypropylene (manufactured by Sanyo Chemical Industry Co., Ltd. product name: Bisco 2 parts by weight 330P) The mixture having the above composition was subjected to the same operation as in Example 1. An electrophotographic toner of the present invention was obtained. The toner thus obtained had a Tg of 62 ° C., a melting start temperature of 100 ° C., and a flow softening point of 128 ° C.

(Example 6) Resin D of Synthesis Example 4 50 parts by weight carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) 5 parts by weight Polycarbodiimide resin 5 parts by weight (trade name: Carbodilite HMV, manufactured by Nisshinbo Industries Inc.) -10B) Chromium-based salt dye (product name: Orient Chemical Industry Co., Ltd .: Bontron 2 parts by weight S-34) Low molecular weight polypropylene (product name: Sanyo Chemical Industry Co., Ltd .: trade name: Viscol 2 parts by weight 330P) The same operation as in Example 1 was performed to obtain an electrophotographic toner of the present invention. The obtained toner had a Tg of 63 ° C., a melting start temperature of 102 ° C., and a flow softening point of 128 ° C.

(Example 7) Resin E of Synthesis Example 5 50 parts by weight carbon black (trade name: MA-100 manufactured by Mitsubishi Chemical Co., Ltd.) 5 parts by weight chromium-based dye salt (trade name: Bontron 2 manufactured by Orient Chemical Industry Co., Ltd.) Parts by weight S-34) Low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Ltd., trade name: Viscol 2 parts by weight 330P) The mixture having the above composition was subjected to the same operation as in Example 1 to obtain the electrophotographic toner of the present invention. It was The obtained toner had a Tg of 64 ° C., a melting start temperature of 103 ° C., and a flow softening point of 129 ° C.

Comparative Example 1 Resin A of Synthesis Example 1 50 parts by weight carbon black (Mitsubishi Chemical Co., Ltd. product name: MA-100) 5 parts by weight chromium-based salt dye (Hodogaya Chemical Co., Ltd. product name: TRH) ) 2 parts by weight low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Ltd .: trade name: Viscole 2 parts by weight 330P) The mixture having the above composition was subjected to the same operation as in Example 1 to obtain a comparative electrophotographic toner. T of the obtained toner
g is 62 ° C., melting start temperature is 99 ° C., flow softening point is 1
It was 23 ° C.

(Comparative Example 2) A comparative electrophotographic toner was obtained in the same manner as in Example 1, except that the resin C in Example 5 was omitted. The obtained toner had a Tg of 63 ° C., a melting start temperature of 105 ° C., and a flow softening point of 133 ° C.

Comparative Example 3 A comparative electrophotographic toner was obtained in the same manner as in Example 1, except that the polycarbodiimide resin of Example 1 was omitted. The obtained toner has a Tg of 60 ° C. and a melting start temperature of 9
The softening point was 5 ° C and the softening point was 120 ° C.

(Comparative Example 4) Resin C of Synthesis Example 3 50 parts by weight carbon black (trade name: MA-100 manufactured by Mitsubishi Chemical Co., Ltd.) 5 parts by weight chromium-based salt dye (trade name: Bontron 2 manufactured by Orient Chemical Industry Co., Ltd.) Parts by weight S-34) Low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Ltd., trade name: Viscol 2 parts by weight 330P) The mixture having the above composition was subjected to the same operation as in Example 1 to obtain a comparative electrophotographic toner. T of the obtained toner
g is 59 ° C., melting start temperature is 84 ° C., flow softening point is 9
It was 8 ° C.

Comparative Example 5 A comparative electrophotographic toner was obtained in the same manner as in Example 1, except that the polycarbodiimide resin from Example 6 was omitted. The toner thus obtained had a Tg of 60 ° C., a melting start temperature of 95 ° C., and a flow softening point of 121 ° C.

Next, the following tests were conducted on the electrophotographic toners obtained from the above-mentioned Examples and Comparative Examples. (1) Non-offset temperature region and non-offset temperature range 5 parts by weight of electrophotographic toner and ferrite carrier (trade name: DFC1 manufactured by Dowa Iron Powder Co., Ltd.) obtained in each example.
50S6) 95 parts by weight was mixed to prepare a two-component developer. Next, using the developer, a commercially available copying machine (manufactured by Sanyo Electric Co., Ltd., trade name Z-133) is used to vertically transfer 2 sheets onto A4 transfer paper.
A plurality of belt-shaped unfixed images each having a size of 5 cm and a width of 5 cm were prepared. Next, a heat-fixing roll (diameter: 40 m, whose surface layer is formed of tetrafluoroethylene resin (Teflon, trade name of DuPont)
m) and a pressure fixing roll (diameter 40 mm) whose surface layer is made of silicone rubber are paired and rotated, and a roll pressure is 1 kg / cm 2 and a roll speed is 25.
The surface temperature of the heat-fixing roll was changed stepwise so that the toner image on the transfer paper having the unfixed image was fixed at each surface temperature. At this time, it was observed whether or not toner stains were generated in the margins, the temperature region where stains did not occur was taken as the non-offset temperature region, and the difference between the maximum and minimum values of the non-offset temperature region was taken as the non-offset temperature width. .

(2) Fixing Strength The surface temperature of the heat fixing roll of the fixing device was set to 160 ° C., and the toner image on the transfer paper on which the unfixed image was formed was fixed. Then, the image density of the formed fixed image was measured using a reflection densitometer (trade name: RD-914, manufactured by Macbeth Co., Ltd.), and then the fixed image was rubbed with a cotton pad, and then similarly. The image density was measured.
The fixing strength was calculated from the obtained measured value by the following formula and used as an index of the low energy toner.

[0048]

[Formula 1] Fixing strength (%) = (image density of fixed image after rubbing / image density before rubbing) × 100 Table 1 shows the measurement results of the above items.

[0049]

[Table 1]

As is clear from the results shown in Table 1, the non-offset temperature region of the electrophotographic toner of the present invention has no offset from low temperature to high temperature, and the non-offset temperature width has a width of 80 ° C. or more. Therefore, it was confirmed that the range was practically sufficient. Further, since the fixing strength at the fixing temperature of 160 ° C. is 70% or more, which is sufficient for practical use, it was confirmed that the low-temperature fixing property is excellent. Further, the image density of the developed image was sufficient, and there was no fog in the non-image portion, which was practically sufficient.

On the other hand, the non-offset temperature region of the comparative example was very narrow except for the comparative example 2, and the non-offset temperature range was not obtained particularly in the comparative example 4. Therefore, there was a problem in practical use. or,
In Comparative Example 2, the non-offset temperature range was about 80 ° C., but the fixing strength at 160 ° C. was 45%, which is very inferior to the toner of the present invention. Further, using each developer and the copying machine of the embodiment in the above item (1), 100
A continuous copy test up to 00 sheets was conducted. As a result, in all the examples, the triboelectrification amount measured by the blow-off triboelectrification amount measuring device (manufactured by Toshiba Chemical Co.) was 10,000 from the beginning.
The value between −25 μc / g and −29 μc / g changes from sheet to sheet, and the image density is maintained at 1.4 or more in the process of continuous copying from the initial stage to 10000 sheets. The background fog in the non-image part measured by Shirosha Co., Ltd., product name: Z-1001DP) was 0.6 or less, and it was confirmed that there was no problem in practical use. Furthermore, even when the toner was left at 50 ° C. for 2 days, neither blocking nor caking was observed.

[0052]

The electrophotographic toner of the present invention has a sufficient non-offset temperature region, can be fixed at a low temperature, has excellent fixing strength, and can obtain a sufficient number of image densities. The effect is that you can. Therefore,
When the electrophotographic toner of the present invention is applied to a copying machine, a printer or the like, it is possible to reduce power consumption, and it is extremely effective in reducing machine cost by lowering the pressure of rolls and increasing the copying speed. is there.

Claims (3)

(57) [Claims] 1. A polyester resin having a crosslinked structure by a reaction with a polycarbodiimide resin having a carbodiimide group represented by the following formula in the molecule, and an ester-based ack.
, Polyethylene, Fischer-Tropschwack
, Α-olefin maleic anhydride and / or maleic anhydride
Acid ester copolymer, oxidized polyethylene wax, stone
At least one low melting point compound selected from oil-based waxes and thermoplastic resins having a melting start temperature of 60 to 100 ° C.
Electrophotographic toner characterized by containing and. ## STR1 ##-N = C = N- 2. The toner for electrophotography according to claim 1, wherein the compounding amount of the low melting point compound is 1 to 40 parts by weight with respect to 100 parts by weight of the polyester resin. 3. The toner for electrophotography according to claim 1, wherein the thermoplastic resin is a linear polyester resin synthesized from diol and / or dicarboxylic acid.