JPH08272140A - Resin composition for toner and electrophotography toner using it - Google Patents

Abstract

PURPOSE: To carry out fixing at a low fixing temperature so as to provide excellent strength for fixing to transfer paper and an excellent image characteris tic by performing condensation polymerization of polyhydric carboxylic acid, its lower alkyl ester, or its anhydride with polyhydric alcohol. CONSTITUTION: In the presence of monoester obtained from long chain straight chain saturated fatty acid and long chain straight chain saturated alcohol, condensation polymerization of polyhydric carboxylic acid, its lower alkyl ester, or its anhydride with polyhydric alcohol is carried out. A peak temperature for a quantity of absorbed heat in a differential scanning calorimetry DSC of the monoester is 40-80 deg.C and the polyhydric carboxylic acid is trivalent or more, while the polyhydric alcohol is trivalent or more. Although a low temperature fixing property is improved as a peak temperature for a quantity of absorbed heat obtained by a differential scanning calorimetry (DSC) is brought down lower, a temperature from 40 deg.C to 80 deg.C is desirable, for a toner preservation property deteriorates at a temperature of 40 deg.C or less while a low temperature fixing properly deteriorates at a temperature of 80 deg.C or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly to a resin composition used for a toner for a copying machine or a printer which employs heat roll fixing, and an electrophotographic toner using the resin composition.

[0002]

2. Description of the Related Art In recent years, electrophotographic copying machines and printers have been widely used in general households and the like. (Reduction of power consumption), high speed for the purpose of spreading to so-called gray area located at the boundary between printing machine and copying machine, or low roll pressure for simplification of fixing roll to reduce machine cost. Is desired. In addition, copiers equipped with a double-sided copy function and an automatic document feeder have become widespread with the sophistication of copiers, and therefore the electrophotographic toner used in copiers and printers has a low fixing temperature and is durable. There is a demand for a sheet having excellent offset properties and excellent fixing strength on a transfer sheet in order to prevent stains during double-sided copying and stains in the automatic document feeder.

In order to meet the above requirements, the prior art has proposed proposals for improving the molecular weight and molecular weight distribution of the binder resin. Specifically, attempts have been made to lower the fixing temperature by lowering the molecular weight of the binder resin. However, when the molecular weight is lowered, the melting point is lowered, but at the same time, the viscosity is also lowered, which causes a problem that an offset phenomenon occurs on the fixing roll. In order to prevent this offset phenomenon, a method of adjusting the low molecular weight region and the high molecular region of the binder resin to widen the molecular weight distribution, or cross-linking the high molecular portion has been performed. However, in this method, the glass transition temperature (Tg) of the resin must be lowered in order to provide sufficient fixability, and impairing the storage stability of the toner cannot be avoided. Further, if the low molecular weight portion of the binder resin is increased, the toner itself becomes brittle, and stains are generated during double-sided copying and stains on the automatic document feeder. Furthermore, there is also a method of incorporating a polyolefin-based release agent in order to prevent the offset phenomenon. However, when the release agent is contained, the melting point of the toner becomes high, so that when fixing at a low temperature, there is a problem that sufficient fixing strength on the transfer paper cannot be obtained. There is also a method of containing a low melting point wax such as carnauba wax, rice wax, and candelilla wax, but the wax is a mixture of several kinds of esters, and free fatty acid and alcohol remain, so that the toner There was a problem with storability.
When a low-melting wax is melt-kneaded with a binder resin, the melting viscosities of the two are extremely different, so that the low-melting wax is poorly dispersed. There is a problem that the toner characteristics are deteriorated because the fixing offset width is narrowed and the charge amount distribution is widened due to the non-uniform melting point wax content.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional toner, and the object thereof is to fix at a low fixing temperature, and even in the non-offset property, some problems occur in practice. In other words, it is to provide an electrophotographic toner having excellent fixing strength on transfer paper and excellent image characteristics.

[0005]

The present invention provides a polycarboxylic acid or a lower alkyl ester thereof or an anhydride thereof in the presence of a monoester obtained from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol. And a polyhydric alcohol are polycondensed with the resin composition for a toner, and an electrophotographic toner containing the resin composition for a toner.

The present invention will be described in detail below. The monoester used in the present invention is synthesized from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol. The long-chain straight-chain saturated fatty acid is represented by the general formula C _n H _{2n + 1} COOH, and n = 5 to 38 or so is preferably used. Specific examples include capric acid, undecyl acid, lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, tetradecanoic acid, octadecanoic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, Cerotic acid, heptacosanoic acid, montanic acid, mesylic acid and the like can be mentioned. The long-chain linear saturated alcohols C _n H _{2n + 1} is represented by OH of about n = 5 to 28 is preferably used. Specific examples include heptadecane 1-ol, dodecane 1-ol, stearyl alcohol, eicosyl alcohol and the like. In addition, if such fatty acid and alcohol have a linear structure having 5 or more carbon atoms, in the range that does not impair the effects of the present invention,
For example, it may have a substituent such as a lower alkyl group, an amino group or halogen. The monoester as described above is prepared, for example, by adding 2 mol of long-chain linear saturated alcohol to 1 mol of long-chain linear saturated fatty acid in a round bottom flask equipped with a stirrer and a condenser, adding a small amount of sulfuric acid, and heating at about 130 ° C. After heating under reflux for 4 hours, excess alcohol is removed, and the residue is obtained by purification with methyl ether or the like.

In the present invention, it is preferable that the monoester has a peak temperature of absorbed heat by differential thermal analysis (hereinafter referred to as DSC) of 40 to 80 ° C. The lower the temperature, the better the low-temperature fixability. However, if the temperature is lower than 40 ° C., the storability of the toner may deteriorate. The method of measuring the peak temperature of the absorbed heat quantity by DSC here is carried out as follows. For example, using a differential scanning calorimeter SSC-5200 manufactured by Seiko Denshi Kogyo Co., Ltd., as measurement conditions, about 10 mg of monoester is weighed and placed on the DSC, and 50 ml of N ₂ gas is blown in for 1 minute.
Then, the process of increasing the temperature between 20 and 150 ° C. at a rate of 10 ° C. per minute and then rapidly cooling from 150 ° C. to 20 ° C. is repeated twice and the absorbed heat amount at that time (second time) is measured. Is.

The toner resin composition of the present invention is a polyester resin obtained by polycondensing a polyvalent carboxylic acid and a polyhydric alcohol in the presence of the monoester. The content of the monoester in the resin composition is preferably 2 to 20 parts by weight when the total amount of the polyvalent carboxylic acid monomer and the polyhydric alcohol monomer described later is 1 part by weight. If the amount is less than 2 parts by weight, the effect on the fixability is small, and if the amount is more than 20 parts by weight, the melt viscosity is too low and high temperature offset occurs, which is not preferable. Specifically, for example, 100 parts by weight of the monoester is charged into a round bottom flask equipped with a stirrer, a condenser, and a nitrogen gas introduction pipe, and heated to about 120 ° C. while introducing nitrogen gas from the nitrogen gas introduction pipe to complete the heating. After being dissolved, about 20 parts by weight of polyvalent carboxylic acid, about 20 parts by weight of polyhydric alcohol and a small amount of a catalyst such as dibutyltin oxide are added, and the mixture is heated at about 160 ° C. for about 2 hours to about 180 ° C.
The resin composition of the present invention can be obtained by polycondensing by heating and stirring at 2 ° C. for 2 hours. The dicarboxylic acid component of the polyvalent carboxylic acid used in the present invention, fumaric acid,
Maleic acid, phthalic acid, isophthalic acid, itaconic acid, glutaconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, alkenylsuccinic acid, glutaric acid, pimelic acid, suberic acid, etc. . Examples of trivalent or higher polycarboxylic acids include 1,2,4-benzenetricarboxylic acid, 2,
5,7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,2,4-butane tricarboxylic acid, 1,2,5-hexane tricarboxylic acid, 1,3-
Dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane,
1,2,7,8-octanetetracarboxylic acid and the like can be mentioned, and lower alkyl ester or anhydride of these polyvalent carboxylic acids can be used.

Examples of the diol component of the polyhydric alcohol of the present invention include polyoxypropylene (2,2) -2,2
-Bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0)
2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol and 1,6-hexanediol may be mentioned. Examples of trihydric or higher polyhydric alcohols include sorbitol, 1,2,3,6-hexanetetrol,
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, 1,3,3. 5-trihydroxybenzene etc. are mentioned. In particular, trivalent or higher polyvalent carboxylic acids and trivalent or higher polyhydric alcohols are preferable because of their excellent compatibility with the monoester.

The electrophotographic toner of the present invention contains at least the resin composition for a toner as described above and a colorant, and if necessary, improves the characteristics of a magnetic material, a charge control agent, a fluidizing agent and the like. Agents can be used. As the binder resin in the toner for electrophotography of the present invention, a resin composition for a toner comprising the above polyester-based condensate is used, but other polyester resin, styrene resin, epoxy resin, silicone resin, polyamide may be used if necessary. You may mix resin, such as resin and polyurethane resin. In this case, the polyester-based condensate is contained in the binder resin in an amount of 50 to 100.
It is preferably blended by weight. If it is less than 50% by weight, the low-temperature fixability, which is the object of the present invention, is difficult to obtain, which is not preferable.

As the colorant, carbon black,
Nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, mixtures thereof, and the like. it can. It is necessary that these colorants be contained in a sufficient concentration to form a visible image, and the amount is usually about 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin.

As the magnetic material, metals or alloys showing ferromagnetism such as ferrite, magnetite and other iron, cobalt, nickel, etc., compounds containing these elements, or no ferromagnetic elements, but suitable heat treatment. An alloy which exhibits ferromagnetism when applied, for example, a type of alloy called a Heusler alloy containing manganese and copper, such as manganese-copper-aluminum, manganese-copper-tin, or chromium dioxide, or the like can be given. .
These magnetic materials are uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.1 to 1 micron. The content is 20 to 70 parts by weight, preferably 40 to 70 parts by weight, per 100 parts by weight of the toner.

The electrophotographic toner of the present invention has a composition as described above, and particularly has a melting start temperature of 60.
Those having a temperature of not less than 100 ° C and less than 100 ° C are preferable. If it is higher than 100 ° C., the low-temperature fixability is not sufficient, and if it is lower than 60 ° C., the blocking property is deteriorated and the storage stability may be deteriorated.
The melting start temperature as used herein refers to the falling start temperature of the plunger under the following measuring machine and measuring conditions. Measuring instrument; Shimadzu's advanced flow tester CF-500 Measuring condition: 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

The electrophotographic toner of the present invention is mixed with a carrier composed of ferrite powder, iron powder or the like to form a two-component developer. When a magnetic substance is contained, it may be used as it is as a one-component developer for developing an electrostatic image without mixing with a carrier, or may be mixed with a carrier and used as a two-component developer. Further, it can be applied to a non-magnetic one-component developing method.

[0015]

EXAMPLES The present invention will be described below based on examples. In the examples, “part” means “part by weight”. <Example 1> 1 mol of tetradecanoic acid, 2 mol of heptadecane 1ol and 0.5 mol of sulfuric acid were placed in a round bottom flask equipped with a stirrer, a condenser and a nitrogen introducing pipe, and while introducing nitrogen gas from the nitrogen gas introducing pipe, 130 The mixture was heated to reflux for 4 hours at 0 ° C. After removing excess heptadecane 1ol, the residue was purified with methyl ether to obtain a monoester. This monoester had a peak temperature of absorbed heat of DSC of 65 ° C. 100 parts of this monoester was placed in a round bottom flask equipped with a stirrer, a condenser and a nitrogen introducing tube, while introducing nitrogen from the nitrogen gas introducing tube.
It was heated to 0 ° C. and completely dissolved. Further, 20 parts of pentaerythritol, 24 parts of terephthalic acid and 0.005 part of dibutyltin oxide were added. Then, the mixture was heated and stirred at 160 ° C. for 2 hours and 180 ° C. for 2 hours to produce a polyester resin, to obtain a toner resin composition (A) of the present invention. Next, the raw materials having the following compounding ratios are mixed in a super mixer, melt-kneaded by a twin-screw kneader, pulverized by a jet mill, and then classified by a dry airflow classifier to obtain an average particle size of 10
μm toner particles were obtained. Next, 100 parts of the toner particles and 0.4 part of hydrophobic silica (trade name: Cabosil TS-530 manufactured by Cabot Corporation) were mixed with each other in a Henschel mixer.
After stirring for a minute, hydrophobic silica was attached to the surface of the particles to obtain the electrophotographic toner of the present invention.

<Example 2> Example 1 except that the long-chain linear saturated fatty acid in Example 1 was changed from tetradecanoic acid to octadecanoic acid and the long-chain linear saturated alcohol was changed from heptadecane 1-ol to dodecane 1-ol. Similarly, a toner resin composition (B) of the present invention was obtained. Next, Example 1
In the compounding ratio of the toner particles of the toner resin composition (A)
An electrophotographic toner of the present invention was obtained in the same manner except that the toner resin composition (B) was used instead of the above. The peak temperature of the absorbed heat of DSC of the monoester was 70 ° C.

Example 3 A toner resin composition (C) of the present invention was obtained in the same manner as in Example 1 except that the amount of pentaerythritol charged was 10 parts and the amount of terephthalic acid charged was 12 parts. Next, an electrophotographic toner of the present invention was obtained in the same manner as in Example 1 except that the toner resin composition (C) was used instead of the toner resin composition (A) in the compounding ratio of the toner particles.

<Example 4> A toner resin composition (D) of the present invention was obtained in the same manner as in Example 1 except that the amount of pentaerythritol charged was 5 parts and the amount of terephthalic acid charged was 6 parts. Next, an electrophotographic toner of the present invention was obtained in the same manner as in Example 1 except that the toner resin composition (D) was used in place of the toner resin composition (A) in the compounding ratio of the toner particles.

Comparative Example 1 Polyester obtained by producing a polyester resin without adding the monoester in the production of the monoester of Example 1 and adding the above monoester instead of the polyester resin of Example 1 A comparative electrophotographic toner was obtained in the same manner as in Example 1 except that a resin was used.

<Comparative Example 2> The monoester of Example 1 and the resin without addition of the monoester of Comparative Example 1 were used in the following formulation, and the production conditions were the same as in Example 1 to obtain a comparative electrophotographic toner. Obtained.

Next, the following items were evaluated for the above Examples and Comparative Examples. (1) Non-Offset Temperature Region First, 4 parts of each electrophotographic toner obtained in the above-mentioned Examples and Comparative Examples and 96 parts of a ferrite carrier (Powder Tech Co., Ltd. product name: FL-1020) not coated with a resin were prepared. A two-component developer was prepared by mixing. Next, a commercially available copying machine (trade name: SF-9, manufactured by Sharp Corporation) is used using the developer.
800), a plurality of belt-shaped unfixed images having a length of 2 cm and a width of 5 cm were formed on an A4 transfer paper. Then, a heat fixing roll having a surface layer made of Teflon and a pressure fixing roll having a surface layer made of silicone rubber are paired and rotated, and a fixing device is rotated at a roll pressure of 1 Kg / cm ² and a roll speed of 50.
The surface temperature of the heat-fixing roll was changed stepwise at intervals of 5 ° C., and 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 the toner was smeared in the blank area, and the temperature region in which the toner was not smeared was set as the non-offset temperature region. (2) Non-offset temperature width The difference between the maximum value and the minimum value in the above non-offset temperature region was defined as the non-offset temperature width.

(3) Fixing Strength The surface temperature of the heat fixing roll of the fixing device was set to 140 ° C., and the toner image on the transfer paper on which the unfixed image was formed was fixed. Then, the formed fixed image was rubbed with a cotton pad, and the fixing strength was calculated by the following formula to be used as an index of low energy fixing property. As the image density, a reflection densitometer RD-914 manufactured by Macbeth was used. Fixing strength (%) = Image density of fixed image after rubbing / Image density of fixed image before rubbing × 100

(4) Image density This is the image density of a fixed image before rubbing when the fixing strength is measured by a reflection densitometer RD-914 manufactured by Macbeth. (5) Melting start temperature According to the measuring instrument and method. Table 1 shows the test results of the above items.

[0024]

[Table 1]

As is clear from the test results of Table 1, the non-offset temperature width of the electrophotographic toner of the present invention is 70-8.
It was confirmed that a practically sufficient range of 5 ° C was maintained. Further, the fixing strength at a fixing temperature of 140 ° C. is 9
It was confirmed that the content was 0% or more and the fixing strength was practically sufficient. On the other hand, in Comparative Example 1, it was confirmed that the fixing strength at 140 ° C. was as low as 50% or less. In Comparative Example 2, the non-offset temperature width was narrow and the image density was low, which was a problem in practical use. In addition, as a result of conducting a continuous copy test up to 10,000 sheets with a commercially available copying machine (trade name: BD-3801 manufactured by Toshiba Corporation) using each developer in the above item (1), Examples 1 to 4 were obtained.
In all of the above, the triboelectric charge amount changed from −18 μc / g to −30 μc / g from the initial stage to 10,000 sheets, and the image density was 1.4 from the initial stage to 10,000 sheets.
It was confirmed that there is no problem in practical use because it changes the value from 0 to 1.50. On the other hand, in Comparative Example 1, the triboelectric charge amount was changed from -20 μc / g to -30 μc / g, and the image density was changed from the initial value of 1.45 to 1.35. 2 has an initial triboelectric charge of -35 μc
The image density was as high as / g and increased to -45 μc / g after 10,000 sheets, and the image density dropped from 1.15 in the initial stage to 0.98 after 10,000 sheets, which was a problem in practical use. The copied original was A4 with a black portion of 6%, and the triboelectric charge amount was measured by using a blow-off triboelectric charge amount measuring device manufactured by Toshiba Chemical Corporation.

[0026]

The toner for electrophotography containing the resin composition of the present invention is capable of fixing at a low temperature while maintaining a sufficient non-offset temperature region, and has excellent fixing strength and sufficient image density. It is possible to obtain a large number of sheets.

Claims (5)

[Claims] 1. In the presence of a monoester obtained from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol, a polyhydric carboxylic acid or a lower alkyl ester thereof or an anhydride thereof and a polyhydric alcohol are mixed. A resin composition for a toner, which is condensed. 2. The resin composition for a toner according to claim 1, wherein the peak temperature of the heat absorption of the monoester by DSC is 40 to 80 ° C. 3. The resin composition for toner according to claim 1, wherein the polyvalent carboxylic acid is a polyvalent carboxylic acid having a valence of 3 or more, and the polyhydric alcohol is a polyhydric alcohol having a valence of 3 or more. . 4. An electrophotographic toner containing at least the resin composition for a toner according to claim 1 and a colorant. 5. The melting start temperature of the toner is 60 ° C. or higher and 10
The toner for electrophotography according to claim 4, wherein the temperature is lower than 0 ° C.