JPH09104741A - Polyester resin for toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin excellent in low-temp. fixability, storage stability, and moisture resistance by combining a specific acid component with a specific alcohol component. SOLUTION: This resin is produced from 1-30mol% (based on the total acid component, and the same applies hereunder) at least tribasic carboxylic acid and/or at least trihydric alcohol, 70-100mol% dicarboxylic acid, 30-110mol% arom. diol represented by formula I (wherein R1 is 3C or lower alkylidene; and 2<=n+m<=4), 1-30mol% arom. diol represented by formula II (wherein R2 is the same as R1 ; and 5<=n+m<=10), and 10-105mol% aliph. diol and has a fusion starting temp. of 80-110 deg.C, a softening point of 100-135 deg.C, a glass transition temperature of 50-70 deg.C, and an acid value of 0.5-20mgKOH/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin useful as a dry toner used for developing an electrostatic image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing, etc. Relates to a polyester resin for toner, which is excellent in low-temperature fixability, storage stability, moisture resistance, and non-offset property.

[0002]

2. Description of the Related Art In a method for obtaining a permanent visible image from an electrostatic charge image, an electrostatic charge image formed on a photoconductive photosensitive member or an electrostatic recording material is developed with a toner charged in advance by friction. Is fixed. In the case of a magnetic latent image,
The latent image on the magnetic drum is developed with toner containing a magnetic material and then fixed. For fixing, the toner image obtained by development is directly fused on the photoconductive photoreceptor or the electrostatic recording body, or the toner image is transferred onto paper or film and then fused onto the transfer sheet. Done by.
Toner image fusion is performed by contact with solvent vapor, pressurization and heating, and there are two types of heating method: non-contact heating method using an electric oven and pressure heating method using a pressure roller. Recently, the latter is mainly used.

Toner used in the dry developing system is 1
There are two-component toners and two-component toners. The two-component toner is prepared by first melt-kneading a resin, a colorant, a charge control agent and other necessary additives to sufficiently disperse them, and then roughly pulverizing them.
Then, it is pulverized and classified into a predetermined particle size range to be manufactured. The one-component toner is manufactured in the same manner by adding magnetic iron powder in addition to the components of the two-component toner.

For this reason, the toner is required to have various performances in order to satisfy the above-mentioned steps, and the performance is often demanded by the binder resin which is the main component of the toner. First, in the latent image process, the toner is required to have stable charging characteristics. Charged physical properties can be dealt with by mixing a charge control agent during toner formulation or by introducing a functional group into the binder resin. Further, in the fixing step, there is a strong demand for lowering the fixing temperature, and improvements such as mixing a fixing aid during toner blending or reducing the molecular weight or lowering the softening temperature in the binder resin are made. I've been broken.

However, when the molecular weight is lowered or the softening temperature is lowered for the purpose of lowering the fixing temperature, another problem that the non-offset property, which is another performance required in the fixing step, is deteriorated. . Further, it has been difficult to reach the currently required fixing temperature with a resin satisfying the non-offset property. Further, a resin that lowers the glass transition temperature of the binder resin to improve the low-temperature fixability has been studied, but since the glass transition temperature of the binder resin is lowered, there arises a problem that the storage stability of the toner becomes poor. .

The binder resin used in the toner includes
Styrene-acrylic resins and polyester resins have been used, but at the present time when vinyl chloride resin resistance to plasticizers or high-definition images are required, improvement by polyester resins is strongly demanded.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and its purpose is to provide low-temperature fixability, storage stability, moisture resistance and non-offset property. Another object of the present invention is to provide an excellent polyester resin for toner.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have used a specific amount of a specific component for an acid component and an alcohol component, and have specific physical properties. The present invention has been completed by finding that the polyester resin possessed can achieve the object.

That is, the present invention provides (a) at least one kind of a polyvalent carboxylic acid component having a valence of 3 or more and / or a polyhydric alcohol component having a valence of 3 or more, which is 1 to 30 mol% based on the total acid component. b) 70 to 100 mol% of divalent carboxylic acid component with respect to all acid components, (c) 30 to 1 with respect to all acid components
10 mol% of at least one aromatic diol represented by the following general formula (I), and 1 to 3 with respect to the total acid component (d).
0 mol% of at least one aromatic diol represented by the following general formula (II), and (e) 10 to 105 mol%
Consisting of a diol component including an aliphatic diol component of
Melting start temperature is 80-110 ° C, softening temperature is 100-1
35 ° C, glass transition temperature 50-70 ° C, acid value 0.5
The polyester resin for toner is characterized in that it is from 20 mgKOH / g.

[0010]

Embedded image

[0011]

Embedded image

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The trivalent or higher polyvalent carboxylic acid and / or the trivalent or higher polyhydric alcohol (a) used in the present invention is a trivalent or higher polyvalent carboxylic acid and a trivalent or higher polyvalent carboxylic acid. It is selected from alcohol. Examples of the trivalent or higher polycarboxylic acid include trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,
Examples thereof include 4-naphthalene tricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,2,7,8-octanetetracarboxylic acid and their acid anhydrides.

Examples of trihydric or higher polyhydric alcohols include:
Sorbitol, 1,2,3,6-hexatetralol,
1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,
4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2
-Methyl-1,2,4-butanetriol, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like. Among these, use of trimellitic acid and its anhydride, pentaerythritol, and trimethylolpropane is particularly preferred.

The above-mentioned component (a) is used alone or in combination of two or more, and it has the effect of increasing the glass transition temperature (hereinafter abbreviated as Tg) of the polyester resin and imparts cohesiveness to the resin. However, it has the effect of increasing the non-offset property, and is used in the range of 1 to 30 mol%, preferably 2 to 28 mol%, based on the total acid components. This is (a)
If the content of the component is less than 1 mol%, a sufficient effect cannot be obtained,
This is because if it exceeds mol%, the Tg of the polyester resin tends to be lowered and the storage stability of the toner tends to be lowered.

Divalent carboxylic acid (b) used in the present invention
Is preferably an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid, and these aromatic dicarboxylic acid components are preferably used as the main component of the acid component.

The amount of component (b) used is in the range of 70 to 100 mol%, preferably 72 to 100 mol%, based on the total acid components. This is because when the amount of the component (b) used is less than 70 mol%, the Tg of the polyester resin is lowered and the storage stability of the toner tends to deteriorate.

The aromatic diol (c) used in the present invention is represented by the above general formula (I). Examples of the aromatic diol (c) include polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene- (2.0)-.
2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene ( 2.2) -2,
2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.
3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.3) -2,2-bis (4
-Hydroxyphenyl) propane, polyoxypropylene (2.4) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.4) -2,2
-Bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (3.3)
-2,2-bis (4-hydroxy) propane etc. are mentioned.

The above-mentioned component (c) is used alone or in combination of two or more kinds, and it has the effect of increasing the Tg of the obtained polyester resin and smoothing the blocking resistance, and with respect to all acid components. It is used in the range of 30 to 110 mol%, preferably 35 to 105 mol%. this is,
When the amount of the component (c) used is less than 30 mol%, the Tg of the obtained polyester resin is lowered and the storage stability of the toner is deteriorated. On the other hand, when it exceeds 110 mol%, the reactivity is lowered. Is.

The aromatic diol (d) used in the present invention is represented by the above general formula (II). As an example of the aromatic diol (d), polyoxypropylene (5) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxyethylene (5) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (6) -2 , 2-bis (4-hydroxyphenyl) propane and the like.

The component (d) has the effect of lowering the melting start temperature of the polyester resin, and is used in the range of 1 to 30 mol%, preferably 3 to 25 mol%, based on the total acid component. In relation to the component (c), the formula [molar part of the component (d)] / {[molar part of the component (d)] +
[Mole part of component (c)]} × 100 = 1 to 50, preferably 2 to 42 is more preferably used. This is because if the amount of the component (d) used is too small, the melting start temperature of the polyester resin becomes high and the fixability of the toner becomes poor, while if the amount of the component (d) used increases, the Tg of the polyester resin decreases. This is because the storage stability of the toner tends to deteriorate.

Examples of the aliphatic diol (e) used in the present invention include ethylene glycol, neopentyl glycol, propylene glycol, butanediol, polyethylene glycol and the like, and they are used alone or in combination of two or more. . These aliphatic diols have an action of improving the polycondensation reaction rate, and among these, ethylene glycol, neopentyl glycol and butanediol are preferably used from the viewpoint of fixing property. The amount of the aliphatic diol used is in the range of 10 to 105 mol%, preferably 15 to 100 mol%, based on the acid component.

The polyester resin for toner of the present invention having the above structure has a melting start temperature of 80 to 110 ° C., preferably 82 to 108 ° C., particularly preferably 85 to 95 ° C.
Softening temperature is 100 to 135 ° C, preferably 102 to 13
3 ° C., particularly preferably 105 to 130 ° C., Tg of 50 to
70 ° C, preferably 52-68 ° C, particularly preferably 55
˜65 ° C., acid value 0.5 to 20 mg KOH / g, preferably 2 to 18 mg KOH / g, particularly preferably 4 to 16
It is important that it is mgKOH / g.

This is because (1) when the melting start temperature is lower than 80 ° C., the storage stability and the fixability are poor, while when the melting start temperature exceeds 110 ° C., the fixability is deteriorated. (2) When the softening temperature is lower than 100 ° C, the storage stability and the non-offset property are poor, while when the softening temperature exceeds 135 ° C, the fixability is deteriorated. (3) When Tg is less than 50 ° C, storage stability is poor, while
If the Tg exceeds 70 ° C., the fixability will decrease. (4) If the acid value is less than 0.5 mgKOH / g, the productivity of the resin will be significantly reduced, while if it exceeds 20 mgKOH / g, the moisture resistance will be poor and the charging characteristics will be poor. This is because of such reasons.

Further, in addition to the above-mentioned characteristics, the polyester resin for toner of the present invention has a maximum molecular weight distribution by gel permeation chromatography of tetrahydrofuran-soluble components in order to improve the low temperature fixing property. The peak molecular weight is preferably in the range of 1,000 to 20,000. This is because when the maximum peak molecular weight is less than 1,000, the storage stability and non-offset property of the toner become poor, while the maximum peak molecular weight is 2 or less.
This is because if it exceeds 50,000, the fixability and pulverizability of the toner will deteriorate. A more preferable maximum peak molecular weight range is 1,500 to 15,000, and a particularly preferable range is 2,000 to 10,000.

In the production of the polyester resin for toner of the present invention, the above-mentioned polymerization components (a) to (e) are charged into a reaction kettle, heated and heated to carry out an esterification reaction or a transesterification reaction. At this time, an esterification catalyst or a transesterification catalyst used in a normal esterification reaction or transesterification reaction such as sulfuric acid, titanium butoxide, dibutyltin oxide, magnesium acetate, and manganese acetate can be used if necessary. . Next, water or alcohol generated by the reaction is removed according to a conventional method.
After that, the polymerization reaction is continuously carried out.
Polymerization is performed while distilling off the diol component under a vacuum of mmHg or less.

In the polymerization, generally known polymerization catalysts such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide and germanium dioxide can be used. Further, the polymerization temperature and the catalyst amount are not particularly limited, and may be arbitrarily set as needed.

In the polyester resin for a toner of the present invention, blocking resistance can be improved by adding an inorganic powder such as silica as required. The effect of adding the silica powder is particularly remarkable when the Tg of the binder resin is low.

Further, when a toner is obtained by using the obtained resin, additives such as carbon black, PP or PE wax, charge control agent and silica can be used together.

Further, the polyester resin for toner of the present invention can be used for heat roll fixing type, flash fixing type or oven fixing type toners. In particular, when the polyester resin for a toner of the present invention is used for a toner of a heat roll fixing system, a temperature at which the toner does not transfer to the roller is 160 ° C. or less under the condition that the roller speed is 150 to 250 mm / sec. The performance can be preferably 150 ° C. or lower, more preferably 140 ° C. or lower. This makes it possible to lower the temperature of the heat roller of a copying machine, a printer or the like, and it is possible to reduce energy consumption.

[0030]

The present invention will be described below in detail with reference to examples. The performance evaluation in Examples and Comparative Examples was performed using the following method.

(1) Tg (glass transition temperature) (° C.) Using a differential scanning calorimeter manufactured by Shimadzu Corporation, a temperature rise of 5 ° C.
The contact point between the tangent line of the endothermic curve near Tg and the baseline when measured at / g was defined as Tg.

(2) Softening temperature (° C.) Flow tester (CFT-50, manufactured by Shimadzu Corporation)
0), the temperature at the time when the sample flowed out half under the conditions of a nozzle 1.0 mmφ × 10 mmL, a load of 30 kgf, a temperature rise of 3 ° C./min, and a sample amount of 1.0 g is defined as a softening temperature (° C.).
And

(3) Melting start temperature (° C.) In the above (2) softening temperature measurement, the temperature at which the outflow started was taken as the melting start temperature.

(4) Acid value (mgKOH / g) The resin was dissolved in benzyl alcohol by heating and then titrated with a KOH solution.

(5) Measurement of molecular weight of maximum peak in molecular weight distribution by GPC (gel permeation chromatography) Using a calibration curve prepared from a monodisperse polystyrene standard sample using GPC HCL-8200 manufactured by Tosoh Corporation, The molecular weight was calculated and the molecular weight distribution was determined from the relationship with the counted values, and the maximum peak thereof was taken as the molecular weight. The sample used was obtained by dissolving and extracting the resin with a solvent (tetrahydrofuran).

(6) Composition analysis The resin was hydrolyzed with hydrazine and quantified by liquid chromatography.

(7) Fixing Property The fixing property was evaluated by using a fixing tester having a roller speed of 200 mm / sec and the temperature being variable. In addition, the minimum temperature when the toner does not migrate to the fixing roller is defined as the minimum fixing temperature, and the fixing property is judged using the following criteria. A: The minimum fixing temperature is 140 ° C. or less, which is excellent. ◯: The minimum fixing temperature is 141 to 150 ° C., which is good. Δ: The lowest fixing temperature is 151 to 160 ° C. but can be used. X: The minimum fixing temperature exceeds 160 ° C. and cannot be used.

(8) Storage stability About 5 g of the sample was weighed and put into a sample bottle, and the sample was left in a dryer kept at 50 ° C. for about 24 hours, and the degree of aggregation of the toner was evaluated to evaluate the storage stability. Was used as an index. The evaluation criteria are as follows. ⊚: Excellent by simply inverting the sample bottle for dispersion. ◯: When the sample bottle is turned upside down and tapped 2-3 times, it is dispersed and can be used practically. X: When the sample bottle is turned upside down and tapped 4 to 5 times or more, it disperses but cannot be used.

(9) Moisture resistance The temperature and humidity during the printing durability test were checked, and changes in image density were evaluated and judged according to the following criteria. ⊚: The image density does not change and is excellent. ◯: Image density decreases due to humidity, but it can be used. X: The image density is lowered due to humidity and the image cannot be used.

(10) Non-Offset Property After the toner is released from the roller and a fixing region is obtained under the same conditions as in the above fixing property evaluation, the toner is transferred to the fixing roller again and the following paper is stained. The temperature at which it occurred was defined as the hot offset generation temperature. The hot offset generation temperature was used as a reference for evaluation. ⊚: The hot offset generation temperature exceeds 200 ° C. and is excellent. ◯: The hot offset generation temperature is 160 to 200 ° C., which is good. Δ: The hot offset generation temperature is 130 to less than 160 ° C. and can be used. X: The hot offset generation temperature is lower than 130 ° C. and cannot be used.

Example 1 Monomers were charged in a reaction vessel equipped with a distillation column in accordance with the composition of polymerization charge shown in Table 1. Next, 500 ppm of antimony trioxide was added to all the acid components, the stirring rotation speed was maintained at 120 rpm to start the temperature rise, and the temperature in the reaction system was heated to 265 ° C. and maintained at this temperature. did. About 8 hours after the water was distilled out from the reaction system and the esterification reaction was started, the water was not distilled off and the reaction was completed. Next, the temperature in the reaction system is cooled and maintained at 230 ° C., the pressure in the reaction container is reduced over about 40 minutes until the degree of vacuum reaches 1.0 mmHg, and the diol component is distilled from the reaction system to carry out the condensation reaction. The stirring torque increases as the reaction proceeds, and the stirring torque is 5 kg-m.
When the pressure reaches, the degree of vacuum is set to 20 mmHg and the stirring torque is gradually increased to a desired stirring torque of 10 kg-m.
When the temperature reached, the pressure in the reaction vessel was returned to normal pressure, and the resin was taken out from the reaction vessel. Table 1 shows the composition analysis results and resin characteristic values of the polyester resins A to E thus obtained.

[0042]

[Table 1]

Next, using the obtained resins A to E, 4 parts by weight of carbon black (# 44 manufactured by Mitsubishi Chemical Co., Ltd.) and PP wax (SANYO CHEMICAL INDUSTRIES, LTD. , 660P), and 1 part by weight of a charge control agent (manufactured by Orient Chemical Industry Co., Ltd., S-34) are mixed, and an internal mixer (manufactured by Kurimoto Iron Works Co., Ltd.) is used to soften the mixture. Melt kneading was performed for 30 minutes at a temperature higher by 10 ° C. Then, the obtained toner lumps are roughly pulverized, finely pulverized by using a jet mill fine pulverizer (manufactured by Nippon Pneumatic Co., Ltd.), and classified by a classifier (manufactured by Nippon Pneumatic Co., Ltd.) to obtain a toner TA having an average particle size of 7 μm. ~ TE was obtained. The toners TA to TE were tested for fixability, storage stability, moisture resistance and non-offset properties. Table 2 shows the results.

[0044]

[Table 2]

The toners TA to TE were good in fixing property, storage stability, moisture resistance and non-offset property.

[Example 2] Polyester resins F to I were obtained in the same manner as in Example 1 except that the composition for polymerization was as shown in Table 3.
The stirring stop torque was 5 kg-m. ). Table 3 shows the composition analysis results and resin characteristic values of the obtained polyester resins F to I.

[0047]

[Table 3]

Next, using the above resins F to I, Example 1
Toners TF to TI were obtained in the same manner as in (however, in the toner TG, the amount of PP wax was 10 parts by weight). The toners TF to TI obtained were tested for fixability, storage stability, moisture resistance and non-offset test. Table 4 shows the results.

[0049]

[Table 4]

Toners TF to TI have fixing property, storage stability,
Both the moisture resistance and the non-offset property were good.

[Example 3] Polyester resins J to N were obtained in the same manner as in Example 1 except that the composition for polymerization was as shown in Table 5. Obtained polyester resins J to N
Table 5 shows the results of composition analysis and resin characteristic values.

[0052]

[Table 5]

Next, using the above resins J to N, Example 1
Toners TJ to TN were obtained in the same manner as in. The toners TJ to TN thus obtained were tested for fixability, storage stability, moisture resistance and non-offset property. Table 6 shows the results.

[0054]

[Table 6]

The toners TJ to TN have fixing property, storage stability,
Both the moisture resistance and the non-offset property were good.

[Comparative Example 1] Polyester resins CA to CF were obtained in the same manner as in Example 1 except that the composition for polymerization was changed to Table 7. However, polyester resin CF
Carried out the condensation reaction for 8 hours, and the torque was 1 kg-m.
The reaction did not proceed with only a slight increase. Resin CA ~
Table 7 shows the CF composition analysis results and resin characteristic values.

[0057]

[Table 7]

Next, the same operations as in Example 1 were performed using the resins CA to CF to obtain toners TCA to TCF. The toners TCA to TCF thus obtained are fixable,
Storage stability, moisture resistance and non-offset tests were conducted. Table 8 shows the results.

[0059]

[Table 8]

Toner TCA was inferior in fixability because of high Tg, melting start temperature, softening temperature and molecular weight of the resin. The toner TCB was inferior in non-offset property because the component (a), which is a crosslinking component of the resin, was not used. T
In CC, since the aromatic diol as the component (d) was not used, the melting start temperature and softening temperature of the resin were high and the fixability was poor. Since the aromatic diol of the component (c) is not used, TCD has a low melting start temperature, softening temperature and Tg of the resin and is poor in non-offset property. Toner TCE
Since a large amount of trimellitic anhydride as the component (a) was used, Tg was lowered, the acid value was increased, and the storage stability and moisture resistance were poor. In the toner TCF, since the amount of the aromatic diol of the component (c) and the aromatic diol of the component (d) used in a large amount, the Tg of the resin, the melting start temperature and the softening temperature are lowered, and the non-offset property is poor, so In the area, the toner was transferred to the roller and the fixing property could not be determined.

[0061]

As described above, the polyester resin for a toner of the present invention is obtained by copolymerizing a specific amount of a specific component with an acid component and an alcohol component, whereby low temperature fixability and storage stability as a binder resin for a toner are obtained. It is possible to provide a toner excellent in resistance, moisture resistance and non-offset property, and is useful as a binder resin for a dry toner used for an electrostatic image or a magnetic latent image in an electrophotographic method, an electrostatic recording method or an electrostatic printing method. Is.

Claims (3)

[Claims] 1. (a) 1 to 30 mol% based on all acid components
At least one polyhydric carboxylic acid component having a valence of 3 or more and / or a polyhydric alcohol component having a valence of 3 or more, (b) a divalent carboxylic acid component of 70 to 100 mol% based on the total acid component, (c) 30 to 110 mol% of at least one aromatic diol represented by the following general formula (I) with respect to all acid components, and (d) 1 to 30 mol% of the following general formula (II) with respect to all acid components. At least one of aromatic diols represented by
And a diol component containing (e) 10 to 105 mol% of an aliphatic diol component and having a melting start temperature of 8
0-110 ° C, softening temperature 100-135 ° C, glass transition temperature 50-70 ° C, acid value 0.5-20mgKOH
Polyester resin for toner, characterized in that it is / g. Embedded image Embedded image 2. The amount of the component (d) used is represented by the formula [molar part of the component (d)] / {[molar part of the component (d)] + [molar part of the component (c)] × 100 = 1. The polyester resin for toner according to claim 1, wherein the polyester resin is in the range of 50 to 50. 3. The toner according to claim 1, wherein the molecular weight distribution of the tetrahydrofuran-soluble component by gel permeation chromatography has a maximum peak molecular weight of 1,000 to 20,000. Polyester resin.