JPH1036490A - Polyester resin for toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin for a toner, which is excellent in melt flow, blocking resistance, low-temp. fixing properties, and anti-offset property. SOLUTION: This resin comprises (a) a dicarboxylic acid component comprising terephthalic acid an/or isophthalic acid as the main component, (b) 0.1 to 1.2 molar %, based on the whole dicarboxylic acid components, of at least one monobasic carboxylic acid component and/or monohydric alcohol component, (c) 20 to 100 molar %, based on the whole acid components, of an aliphatic diol component, and (b) another diol component. Thus resin has a glass transition temp. of 45 to 70 deg.C, a softening temp. of 90 to 130 deg.C, a wt.-average mol.wt. (Mw) of 3,000 to 30,000, a no.-average mol.wt. (Mw) of 1,500 to 14,000, and a negative charge of 3μC/g or below when it is in the from of fine particles having a nol.-average particle diameter of 5 to 15μm.

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, and the like. Excellent in anti-blocking properties, melt fluidity, low-temperature fixability and charging properties as toner, especially useful for full-color applications requiring high melt fluidity, high-speed copiers and high-speed printers requiring low-temperature fixability And a polyester resin for toner.

[0002]

2. Description of the Related Art In a method for obtaining a permanent visual image from an electrostatic image, a method is used in which an electrostatic image formed on a photoconductive photoreceptor or an electrostatic recording medium is developed by a toner previously charged by friction. Is established. For a magnetic latent image,
After developing with toner containing latent image on magnetic drum,
Be established. Fixing is performed by directly fusing a toner image obtained by development on a photoconductive photoreceptor or an electrostatic recording medium, or by transferring a toner image onto paper or a film and then fusing it on a transfer sheet. This is done by: The fusion of toner images is performed by contact with solvent vapor, pressurization and heating. There are two types of heating methods: non-contact heating using an electric oven and pressure heating using a pressure roller. Recently, the latter is mainly used.

[0003] Toner used in the dry development system includes 1
There are two-component toners and two-component toners. A two-component toner is manufactured by first melting and kneading a resin, a charge control agent and other necessary additives to sufficiently disperse, then coarsely pulverizing, then finely pulverizing, and classifying into a predetermined particle size range. You. 1
The component-based toner is similarly manufactured by adding magnetic iron powder in addition to the components of the two-component toner.

[0004] Resin is the main component in the compounding of the toner and therefore controls most of the performance required for the toner. For this reason, resins for toners are required to have good dispersibility of the colorant in the melt-kneading step and good pulverizability in the pulverizing step in the production of the toner. Various performances are required, such as good properties, blocking resistance, and good electrical properties. Epoxy resins, polyester resins, polystyrene resins, methacrylic resins, and the like are known as resins used in the production of toners. For the pressure fixing method, a copolymer of styrene and (meth) acrylate is mainly used. Has been used.

Furthermore, in order to obtain a color image, in the above-mentioned developing step, toner of three to four colors must be adhered to the transfer paper, and then, in the fixing step, the color is formed while being melted and mixed, and fixed. Must. For this reason, as described above, there is a strong demand for a binder for a full-color toner which has good mixing properties in the fixing step, in other words, a resin having good melt fluidity.

However, when a binder having good melt fluidity is used, there is a problem that an offset phenomenon occurs in a fixing step. On the other hand, if the binder has a crosslinked structure or is polymerized in order to prevent the offset phenomenon, the melt fluidity is reduced, so that the binder resin is not suitable as a binder resin for a full-color toner. Therefore, in the case of a full-color copying machine, silicone oil or the like is applied to the surface of the fixing roller in order to obtain non-offset properties. For this reason, a method for preventing offset such as applying silicone oil to a fixing roller has been used in general copying machines and printers other than full-color, for which high speed and energy saving of a fixing unit are strongly desired. .

A binder resin for a full-color toner or a toner for a high-speed copying machine needs to be reduced in viscosity due to melt mixing and low energy melting. Generally, it is necessary to lower the molecular weight in order to lower the viscosity of the polymer. When the molecular weight is reduced, the number of terminal carboxyl groups and hydroxyl groups inevitably increases, the moisture resistance of the resin is reduced, and the charge stability of the toner is impaired. Further, the polyester resin tends to have a high negative charge as a resin, and when used as a positively chargeable toner, it is difficult to stably maintain the positive charge of the toner.

On the other hand, as a method of solving this problem, a method of maintaining a charge amount by using a large amount of a charge control agent is conceivable. However, this causes a problem of increasing the price of the toner. There is a problem that it is difficult to adjust the color tone by the charge control agent.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a resin having good melt fluidity and low-temperature fixability and excellent blocking resistance. An object of the present invention is to provide a toner resin which can provide a toner and has a low negative charge amount of the resin itself.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, they have used a specific amount of a specific component for an acid component and an alcohol component, and also obtained a specific monobasic carboxylic acid. The inventors have found that a polyester having specific physical properties and / or containing a monohydric alcohol as a polymer component can achieve the above object, and the present invention has been completed.

That is, the present invention provides (a) a dicarboxylic acid component containing terephthalic acid and / or isophthalic acid as a main component, and (b) 0.1 mol% or more and 1.2 mol% or less based on all dicarboxylic acid components. At least one of a monobasic carboxylic acid component and / or a monohydric alcohol component, (c)
It is composed of an aliphatic diol component of 20 mol% or more and 100 mol% or less based on all acid components, and (d) other diol components, and has a glass transition temperature of 45 ° C. to 70 ° C. and a softening temperature of 90 ° C. or more. 130 [deg.] C. or less, weight average molecular weight Mw of 3,000 or more and 30,000 or less, number average molecular weight Mn of 1,500 or more and 14,000 or less, and negative charge amount of 3 [mu] C when formed into fine particles having a volume average particle size of 5 to 15 [mu] m.
/ G or less.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The dicarboxylic acid component (a) containing terephthalic acid and / or isophthalic acid as a main component used in the present invention is selected from terephthalic acid, isophthalic acid and lower alkyl esters.
Examples of lower alkyl esters of terephthalic acid and isophthalic acid include dimethyl terephthalic acid, dimethyl isophthalic acid, diethyl terephthalic acid, diethyl isophthalic acid, dibutyl terephthalic acid, dibutyl isophthalic acid, etc. Terephthalic acid and dimethyl isophthalic acid are preferred.
These aromatic dicarboxylic acid components have the effect of increasing the glass transition temperature (hereinafter abbreviated as Tg) of the resin and contributing to the improvement of the blocking resistance of the toner. For this reason, terephthalic acid and / or isophthalic acid is preferably contained in an amount of 60 to 100 mol%, more preferably 80 to 100 mol%, based on all dicarboxylic acid components.

In the present invention, examples of other dicarboxylic acids which can be used in combination with the above aromatic dicarboxylic acids include phthalic acid, sebacic acid, isodecyl succinic acid,
Dodecenyl succinic acid, maleic acid, fumaric acid, adipic acid and their monomethyl, monoethyl, dimethyl,
Examples include diethyl esters and their acid anhydrides. These dicarboxylic acid components are used in the T of the resulting resin.
In order to reduce g and greatly affect the fixing property and the blocking resistance of the toner, the content is preferably 40 mol% or less, more preferably 20 mol% or less in all dicarboxylic acid components.

In the present invention, the monobasic carboxylic acid and / or
Alternatively, the monohydric alcohol (b) is selected from monobasic carboxylic acids and monohydric alcohols. Examples of monobasic carboxylic acids include benzoic acid, p-substituted benzoic acid, o
-Substituted benzoic acid, acetic acid, propionic acid, butyric acid and the like. Examples of monohydric alcohols include benzyl alcohol, p-substituted benzyl alcohol, o-substituted benzyl alcohol, lauryl alcohol, myristyl alcohol, stearyl alcohol and the like. The above-mentioned component (b) is used alone or as a mixture of two or more kinds, and reduces the amount of negative charge of the polyester obtained by ester bonding to the terminal of the polymer molecule. The amount of negative charge when the particles are
C / g or less, and the charge stability of the toner can be improved. Therefore, even when the toner is used as a positively chargeable toner, the positive charge amount of the toner can be stably maintained. The component (b) needs to be in a range of 0.1 mol% to 1.2 mol%, preferably 0.1 mol% to 1 mol%, based on all dicarboxylic acid components. Yes, more preferably 0.15
It is in the range of not less than mol% and not more than 0.5 mol%. this is,
When the amount of the component (b) is less than 0.1 mol%, the amount of negative charge cannot be sufficiently reduced. When the amount exceeds 1.2 mol%, the softening temperature of the resin decreases, and the cohesive force decreases. The molecular weight of the toner cannot be increased, and the blocking resistance of the toner decreases.

The component (b) is preferably used in an appropriate range depending on the degree of softening temperature of the resin.
Softening temperature x (° C.) and total amount y of monobasic carboxylic acid component and / or monohydric alcohol component with respect to all dicarboxylic acids
(Mol%) is preferably contained so as to satisfy the following formula (I).

131.3 × (0.948) ^x <y <97.0 × (0.948) ^x (I)

[0017] This, in the above formula (I), the total amount y is 131.3 × (0.948) when ^x is smaller than the low charge quantity to introduced amount of the component (b) to the polymer end is reduced Is not obtained, and the total amount y is 97.0 ×
If it is larger than (0.948) ^x , the obtained resin has a low Tg, and the toner has poor blocking resistance.

The aliphatic diol (c) used in the present invention includes ethylene glycol, neopentyl glycol, 1,2-propanediol, 1,4-
Butanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A and the like can be mentioned, and one kind or two or more kinds are used in combination. Among them, ethylene glycol, neopentyl glycol,
1,4-cyclohexanedimethanol is preferred. In particular, ethylene glycol can increase the reactivity. The aliphatic diol is at least 20 mol% and 100 mol% based on the total acid components.
Mol% or less, preferably 30 mol% or more and 80 mol% or less.

The other diol (d) used in the present invention includes the above-mentioned aliphatic diol (c)
And specific examples thereof 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- (6.0)-
2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -2,2-bis (4-
Hydroxyphenyl) propane, polyoxyethylene-
(2.3) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene- (2.3) -2,2
-Bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.4) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene-
(3.3) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene- (5.0) -2,2
Aromatic diols such as -bis (4-hydroxyphenyl) propane; polyether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, and polytetramethylene glycol, and the like. These may be used alone or in combination of two or more. Used.

Among the above components (d), aromatic diols have the effect of increasing the Tg of the resin, and are particularly effective in polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane. Oxypropylene- (2.
3) The use of -2,2-bis (4-hydroxyphenyl) propane is preferred.

On the other hand, the polyether glycol used as the component (d) has the effect of lowering the Tg of the resin and improving the fixability. For this reason, aromatic diols and polyether glycols are used to adjust the Tg of the resin. However, since they are liable to undergo thermal decomposition at high temperatures, they are not suitable for use with aromatic dicarboxylic acids that require a high reaction temperature. , Its quantity is limited. Its content is 8 to the total dicarboxylic acid component.
0 mol% or less, more preferably 7 mol% or less.
0 mol% or less.

In the present invention, as long as the properties of the polyester resin are not impaired, monomers other than those described above may be used in a range of 10 mol% or less based on all the acid components.

The polyester resin for a toner of the present invention having the above constitution has a Tg of 45 to 70 ° C., preferably 50 to 70 ° C.
~ 70 ° C, softening temperature 90 ~ 130 ° C, preferably 95
~ 120 ° C, weight average molecular weight Mw of 3,000 ~ 30,
000, preferably 4,000 to 16,000, fine particles having a number average molecular weight Mn of 1,500 to 14,000, preferably 2,000 to 8,000, and a volume average particle size of 5 to 15 μm, have a negative charge amount of It is necessary that the concentration be 3 μC / g or less, preferably 2.3 μC / g or less, and more preferably 2 μC / g or less.

(1) When the Tg is lower than 45 ° C., the blocking resistance is poor. On the other hand, when the Tg is higher than 70 ° C., the blocking resistance is improved, but the fixing performance is remarkably deteriorated. (2) When the softening temperature is lower than 90 ° C., the fixing property is improved, but the cohesive force of the resin is reduced, while the softening temperature is 130 ° C.
If the ratio exceeds the above range, the melt fluidity and the low-temperature fixability decrease. (3) When the weight average molecular weight Mw is less than 3,000 and the number average molecular weight Mn is less than 1,500, Tg is remarkably reduced and the blocking resistance is deteriorated, while the weight average molecular weight Mw exceeds 30,000, And number average molecular weight Mn
If it exceeds 14,000, the melt fluidity and the low-temperature fixability decrease. (4) In the case of fine particles having a volume average particle diameter of 5 to 15 μm, if the negative charge amount exceeds 3 μC / g, a stable charge amount cannot be obtained. This is because of such reasons.

In the production of the polyester resin for a toner of the present invention, the above-mentioned polymerization components (a) to (d) and, if necessary, other polymerization components are charged into a reaction vessel.
The temperature is increased by heating to perform 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. . Then, according to the usual method,
The water or alcohol formed in the reaction is removed. Thereafter, a polycondensation reaction is subsequently carried out.
The polymerization is carried out while distilling and removing the diol component under a vacuum of not more than Hg.

For the polymerization, known polymerization catalysts such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide and the like can be used. Further, the polymerization temperature and the amount of the catalyst are not particularly limited,
It may be set arbitrarily 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 the addition of the silica powder is particularly remarkable when the Tg of the resin is low.

[0028]

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, the temperature was raised to 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) Composition analysis The resin was hydrolyzed with hydrazine and quantified by liquid chromatography.

(4) Weight average molecular weight Mw, number average molecular weight Mn Measured by GPC HCL-8200 manufactured by Tosoh Corporation.

(5) Volume average particle size, charge amount Measured by an E-SPART analyzer manufactured by Hosokawa Micron Corporation.

(6) Melt fluidity A resin powder is evenly spread on a vinyl chloride resin sheet having a thickness of 0.15 mm (amount of 250 mg per area of 10 cm × 10 cm), and it is applied to silicon oil (Shin-Etsu Chemical Co., Ltd.) KF96-30) was applied and passed through a fixing roller set at a temperature of 160 ° C. at a speed of 300 mm / min to melt the resin powder layer. Next, the sheet was projected on a screen with a projector, and the light transmittance was measured to evaluate the melt fluidity.

In the above method, if the resin has good melt fluidity, the resin spreads evenly on the sheet, and the resin layer can easily transmit light. Since the surface of the resin layer on the sheet is not smooth, the transmitted light is scattered and a shadow occurs. In the present invention,
In the following evaluation criteria, A and B were regarded as having good melt fluidity. A: Light is easily transmitted. B: Light scattering occurs slightly. C: Light is scattered and a shadow is formed.

(7) Blocking Resistance 5 g of the same resin powder as used in the evaluation of melt flowability was placed in a 50 ml glass sample bottle, left in a constant temperature bath at 40 ° C. for 24 hours, and then cooled to room temperature. The degree of aggregation of the resin powder was observed. The degree of aggregation was evaluated by the following method. In the present invention, the cohesion degrees A and B are regarded as having good blocking resistance. A: Resin powder drops just by inverting the sample bottle. B: Invert the sample bottle and shake lightly to drop the resin powder. C: The resin bottle falls when the sample bottle is turned upside down and tapped lightly. D: When the sample bottle is turned upside down and strong vibration is applied, the resin powder falls. E: Even if the sample bottle is turned upside down and strong vibration is applied, the resin powder does not fall.

Example 1 50 mol% of terephthalic acid (the same applies to all dicarboxylic acid components), 50 mol% of isophthalic acid, 100 mol% of ethylene glycol, Pt
ert-benzoic acid 0.3 mol%, polyoxyethylene-
(2.0) -2,2-bis (4-hydroxyphenyl)
20 mol% of propane (diol B) was charged into a reaction vessel equipped with a distillation column. Further, 0.06 parts by weight of antimony trioxide as a catalyst was added to all dicarboxylic acid components, the internal temperature was maintained at 260 ° C., and the stirring rotation speed was 200 rpm.
The esterification reaction was carried out at normal pressure for 6 hours. Thereafter, the pressure inside the reaction system was reduced to 1.0 mmHg over 30 minutes, and the internal temperature was reduced to 220 mmHg.
C., and the condensation reaction was carried out for 4 hours while distilling off ethylene glycol to obtain a pale yellow transparent resin R-1. Table 1 shows the composition analysis result and the resin physical properties of the obtained resin R-1.

Next, the obtained resin R-1 is roughly pulverized and then jet milled (manufactured by Nippon Pneumatic Co., Ltd.).
And ground to 15 μm or less. Thereafter, classification was performed using an air classifier (manufactured by Nippon Pneumatic Co., Ltd.). Using the resin powder, tests for melt fluidity and blocking resistance were performed. Table 1 shows the results.

Next, 95 g of a ferrite carrier (particle size: 60 μm) was mixed with 5 g of the above resin powder, and the mixture was stirred for 30 minutes, and then the volume average particle size and the charge amount were measured. Table 1 shows the results. Resin R-1 had good melt fluidity, blocking resistance and negative charge.

[Examples 2 to 4] Resins R-2 to R-4 were obtained by performing the same operations as in Example 1 except for changing the polymerization charge composition as shown in Table 1. Table 1 shows the composition analysis results and the resin physical properties of the resins R-2 to R-4.

Next, using the above resins R-2 to R-4,
The same operation as in Example 1 was performed to evaluate the performance.
Table 1 shows the test results for the melt fluidity, the blocking resistance, and the negative charging property. Resins R-2 to R-4 had good melt fluidity, blocking resistance and negative charge.

[0042]

[Table 1]

Comparative Examples 1 to 4 Resins R-5 to R-8 were obtained by performing the same operations as in Example 1 except that the polymerization charge compositions were as shown in Table 2. Table 2 shows the results of the composition analysis and the resin physical properties of the resins R-5 to R-8. Next, the same operation as in Example 1 was performed using the above resins R-5 to R-8 to evaluate the performance. Table 2 shows the test results of the melt fluidity, the blocking resistance, and the negative charging property.

Resin R-5 had a low amount of a monobasic carboxylic acid component and a high softening temperature, and therefore had poor melt fluidity and a high negative charge. Resin R-6 had a low amount of aliphatic diol component, an excessive amount of monobasic carboxylic acid component, and a too low softening temperature, resulting in poor blocking resistance and a high negative charge. Resin R-7 had a high negative charge because the amount of the monohydric alcohol component was small. Resin R-8 had poor blocking resistance due to an excessive amount of the monobasic carboxylic acid component.

[0045]

[Table 2]

[0046]

As described above, the polyester resin for a toner according to the present invention is obtained by introducing a monobasic carboxylic acid component and / or a monohydric alcohol component into a polymer to provide blocking resistance, melt fluidity and charging performance. It is useful as a resin for a dry toner used for an electrostatic image or a magnetic latent image in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc., and particularly has a charge amount as a resin for a positively chargeable toner. It is preferable because it can be stably maintained. Further, the polyester resin for a toner of the present invention is useful as a toner resin for a full color, which requires high melt fluidity, and for a high-speed copying machine and a high-speed printer, which requires low-temperature fixability.

Claims (2)

[Claims] 1. A dicarboxylic acid component containing (a) terephthalic acid and / or isophthalic acid as a main component, and (b) 0.1 mol% or more and 1.2 mol% based on all dicarboxylic acid components.
At least one of the following monobasic carboxylic acid components and / or monohydric alcohol components, (c)
0 mol% or more and 100 mol% or less of an aliphatic diol component,
And (d) other diol components, having a glass transition temperature of 45 ° C to 70 ° C and a softening temperature of 90 ° C.
℃ to 130 ° C, weight average molecular weight Mw of 3,000
Not less than 30,000 and a number average molecular weight Mn of 1,500
A polyester resin for toner, having a negative charge of 3 μC / g or less when the fine particles have a volume average particle diameter of 5 to 15 μm or less. 2. The softening temperature x (° C.) and the total amount y (mol%) of a monobasic carboxylic acid component and / or a monohydric alcohol component with respect to all dicarboxylic acid components satisfy the following formula (I). The polyester resin for a toner according to claim 1, wherein 131.3 × (0.948) ^x <y <97.0 × (0.948) ^x (I)