JPH07181734A - Polyester resin for toner - Google Patents

Abstract

(57) [Abstract] [Purpose] To develop a polyester resin for toner which is excellent in blocking resistance, melt flowability, low temperature fixing property and offset resistance. [Structure] (a) Dicarboxylic acid component containing 60 mol% or more of aromatic dicarboxylic acid with respect to all acid components, and (b) 5 mol% or more of aromatic diol (I) with respect to all acid components 5 mol% relative to diol component and (c) total acid component
A polyester resin comprising the above diol component containing an aromatic diol (II) and having a softening temperature of 90 to 1
Polyester resin for toner having a glass transition point Tg of 50 to 80 ° C. at 30 ° C.

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. More specifically, it is a polyester for toner which is excellent in blocking resistance, melt fluidity and low-temperature fixability, and is particularly useful for high-speed copying machines and high-speed printers that require high melt fluidity and low-temperature fixability. Regarding resin.

[0002]

2. Description of the Related Art In a method of obtaining a permanent visible image from an antistatic image, an electrostatic 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. A 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, then coarsely pulverizing them and then finely pulverizing them to classify them into a predetermined particle size range. Manufactured. The one-component toner is manufactured in the same manner by adding magnetic iron powder in addition to the respective components of the above two-component toner.

Since the resin is the main component in the toner formulation, it controls most of the performance required for the toner. For this reason, the toner resin is required to have good dispersibility of the colorant in the melt-kneading step and good pulverizability in the pulverizing step in the toner production.
Various performances such as good offset property, blocking property, and good electrical property are required. Resins used in the production of toner include epoxy resins, polyester resins,
Polystyrene resins, methacrylic resins and the like are known, but copolymers of styrene and (meth) acrylic acid ester have been mainly used for the pressure-bonding heat fixing system. But,
Polyester resins have been attracting attention because they can be fixed at lower temperatures and the toner images on which they are fixed have excellent PVC plasticizer resistance.

On the other hand, in order to obtain a color image, it is necessary to adhere toners of 3 to 4 colors to the transfer paper in the above-mentioned developing process, and then, in the fixing process, various colors are fused and mixed while being fused and fixed. . Therefore, as the binder resin for the full-color toner, a resin having a good mixing property in the fixing process as described above, in other words, a resin having a good melt fluidity is strongly desired. However, when a binder resin having a good melt fluidity is used, there is a problem that an offset resistance phenomenon occurs in the fixing process. When the binder resin is cross-linked to prevent the offset resistance phenomenon, the melt fluidity is lowered, and thus it 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 offset resistance. However, if silicone oil or the like is applied to the surface of the fixing roller, the oil may adhere to the copy, which may hinder the handling. Especially, when copying to OHP or the like, this phenomenon is remarkable.

By the way, polyester resin is used as a binder resin for full color, but in general, polyester resin has a Tg when its viscosity is lowered and high fluidity is imparted.
And the blocking resistance deteriorates. As a method for simultaneously satisfying such contradictory physical properties, it has been proposed to use a propylene oxide adduct of bisphenol A as a diol component for condensation. But,
This adduct has (1) extremely poor reactivity, and the acid component is restricted in order to allow the reaction to proceed to an arbitrary degree of polymerization.
(2) Further, the obtained polymer is also very brittle because of its low molecular weight, and the generation of fine powder is great during the toner production, and the yield is lowered. (3) Further, there is a problem that the fixing strength of the obtained toner copy is also lowered.

In order to solve these problems, it has been proposed to use an ethylene oxide adduct having relatively high reactivity even in a bisphenol A derivative, but the ethylene oxide adduct of bisphenol A causes a decrease in Tg. Because it brings, it cannot be used much. Also, since the ethylene oxide adduct of bisphenol A is a solid, it needs to be pulverized when used as a monomer, which increases the cost, and the resin using it is a popular copying machine / printer. Is not suitable for use. Further, when polymerizing a polymer, there is a problem that the ethylene oxide adduct of bisphenol A, which is a block, is difficult to make into a slurry and the amount used is limited.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and its object is to have excellent blocking resistance, melt flowability and low-temperature fixability. To provide a polyester resin for a toner. Still another object of the present invention is to obtain a polyester resin for a toner, which imparts toughness to the toner, is inexpensive, and has good polymerization stability.

[0009]

As a result of intensive investigations aimed at achieving the above-mentioned object, the present inventors have found that a polyester resin containing a specific aromatic diol as a polymer component can achieve the object. Completed the invention. That is, the present invention relates to (a) a dicarboxylic acid component containing 60 mol% or more of an aromatic dicarboxylic acid with respect to the total acid component,
(B) a diol component containing 5 mol% or more of an aromatic diol represented by the following formula (I) with respect to the total acid component; and (c)
A polyester resin comprising a diol component containing 5 mol% or more of an aromatic diol represented by the following formula (II) based on all acid components, having a softening temperature of 90 to 130 ° C. and a glass transition point Tg (hereinafter, (Abbreviated as Tg) is 50 to 80.
The polyester resin for toner is characterized in that it is at a temperature of ℃.

[0010]

[Chemical 3]

[0011]

[Chemical 4]

The aromatic dicarboxylic acid (a) used in the present invention is selected from aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and their lower alkyl esters. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include, for example, dimethyl terephthalic acid, dimethyl isophthalic acid, diethyl terephthalic acid,
Examples thereof include diethyl isophthalic acid, dibutyl terephthalic acid, and dibutyl isophthalic acid, and dimethyl terephthalic acid and dimethyl isophthalic acid are preferable in terms of cost and handling. The above aromatic dicarboxylic acids or lower alkyl esters thereof may be used alone or in combination of two or more. The aromatic dicarboxylic acid is the T of the resulting resin.
g to contribute to the improvement of blocking resistance, and because of its hydrophobicity, it is also effective for moisture resistance. Therefore, it is necessary to use the aromatic dicarboxylic acid in an amount of 60 mol% or more, preferably 70 mol% or more, based on all acid components. Among them, the terephthalic acid type is effective in increasing the Tg of the resin, and the isophthalic acid type is effective in increasing the reactivity, so that it is necessary to change the use balance depending on the purpose.

In the present invention, other dicarboxylic acids which can be optionally used in combination with the above aromatic dicarboxylic acids include, for example, phthalic acid, sebacic acid, isodecyl succinic acid, fumaric acid, adipic acid and these. Monomethyl, monoethyl, dimethyl, diethyl ester and the like, and acid anhydrides thereof. Since these dicarboxylic acids have a great influence on the fixing property and blocking resistance of the toner, it is necessary to consider these properties before use. It is preferably used in the range of 30 mol% or less based on the total acid component.

The aromatic diol (b) represented by the above formula (I) used in the present invention has a Tg of resin.
Is a component for controlling reactivity. Formula (I)
Examples of the aromatic diol represented by are polyoxypropylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.
3) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.8) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (3.0) -2 , 2-bis (4-hydroxyphenyl) propane and the like, which may be used alone or in admixture of two or more. The amount of the aromatic diol of the formula (I) used is 5 mol% or more based on all acid components,
It is preferably in the range of 20 to 80 mol%. This results in a decrease in the Tg of the resin when the amount used is less than 5 mol%,
This is because the blocking property of the toner is lowered. Further, when it is used in excess of 80 mol%, the reactivity is remarkably lowered and the reaction does not proceed up to the desired degree of polymerization, and it is preferably used in the range of 70 mol% or less.

Further, the aromatic diol (c) represented by the above formula (II) used in the present invention is a component which enhances the molecular orientation and imparts toughness to the resin to improve the reactivity. Examples of the aromatic diol represented by the formula (II) include polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2.3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2.8)-
2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (3.0) -2,2-bis (4-hydroxyphenyl) propane and the like can be mentioned, among which polyoxyethylene- (2.3) -2,2-bis (4-hydroxyphenyl) propane is preferred from the viewpoints of high Tg, reactivity and handling. These are used alone or in combination of two or more. The amount of the aromatic diol (c) used is 5 mol% or more, preferably 1
It is in the range of 0 to 70 mol%. This is because when the amount used is less than 5 mol%, the orientation of the molecules decreases and the toughness decreases. Further, if it is used in an amount of more than 70 mol%, it becomes difficult to form a slurry at the time of charging the raw materials and the productivity is lowered.

In the present invention, it is essential to use the above components (b) and (c) together, and the object of the present invention cannot be achieved even if either component is lacking. The total amount of the components (b) and (c) used is preferably in the range of 20 to 80 mol% based on the total acid components in terms of reactivity and cost. In the present invention, by using the components (b) and (c) in combination, a toner resin having a well-balanced reactivity, higher Tg, fixability and productivity can be obtained.

Further, in the present invention, an aliphatic diol can be used in combination with the above aromatic diol as a diol component. As examples of aliphatic diols,
Examples thereof include ethylene glycol, neopentyl glycol, propylene glycol, butanediol, polyethylene glycol and the like, and these may be used alone or in admixture of two or more. These aliphatic diols have a function of improving the polycondensation reaction rate. Of these, ethylene glycol, neopentyl glycol, and butanediol are preferably used from the viewpoint of fixability. The amount of the aliphatic diol used is preferably in the range of 20 mol% or more based on the total acid components.

The polyester resin for toner of the present invention having the above constitution has a softening temperature of 90 to 130 ° C., preferably 95 to 120 ° C. and a Tg of 50 to 80 ° C., preferably 5
It is necessary to be 5 to 70 ° C. This is because when the softening temperature of the polyester resin is lower than 90 ° C., the cohesiveness of the polymer itself is extremely lowered, the cohesive force of the resin is lowered, and the offset resistance is deteriorated. When it exceeds the above range, the offset resistance tends to be a preferable direction, but the melt-mixing property is deteriorated and the color mixing property is deteriorated. Further, when Tg is less than 50 ° C., the fixability is improved, but the blocking resistance is significantly reduced. On the other hand, when Tg exceeds 80 ° C., the blocking resistance is improved but the fixability is lowered.

In the production of the polyester resin for toner of the present invention, the above-mentioned polymerization components (a) to (c) are charged into a reaction kettle, heated and heated to carry out an esterification reaction or a transesterification reaction. At this time, if necessary, an esterification catalyst or a transesterification catalyst used in a usual esterification reaction or transesterification reaction such as sulfuric acid, titanium butoxide, dibutyltin oxide, magnesium acetate, manganese acetate can be used. . Then, water or alcohol generated in the reaction is removed according to a conventional method. After that, the polymerization reaction is continued, but at this time, 150 m
Polymerization is performed while distilling off the diol component under a vacuum of mHg or less.

In the polymerization, generally known polymerization catalysts such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, 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 toner of the present invention, if necessary, inorganic powder such as silica may be added to improve blocking resistance. The effect of adding the silica powder is particularly remarkable when the Tg of the binder resin is low. However, regarding resins having Tg of 40 ° C or less, the effect of improving blocking resistance is not remarkable.

[0022]

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

(1) Softening temperature (° C.) Shimadzu Corporation Flow Tester (CFT-50)
0) was used as the softening temperature (° C.) when the sample half flowed out under the conditions of nozzle 1.0 mmφ × 10 mmL, load 30 kg, temperature increase 3 ° C./min, sample amount 1.0 g.

(2) Tg (glass transition point) (° C.) Using a differential scanning calorimeter manufactured by Shimadzu Corporation, a temperature rise of 5 ° C.
The contact point between the base line and the tangent line of the endothermic curve in the vicinity of Tg when measured in / min was defined as Tg.

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

(4) Blocking resistance 5 g of toner was placed in a glass sample bottle and the temperature was adjusted to 50
It was left for 50 hours under the condition of ° C and humidity of 65%. afterwards,
The sample was cooled to room temperature, the aggregated state was visually observed, and evaluated according to the following criteria. A: Toner drops when the sample bottle is turned upside down. B: The toner drops when the sample bottle is turned upside down and shaken lightly. C ... The toner drops when the sample bottle is turned upside down and tapped from above. D: The toner drops when the sample bottle is turned upside down and hit hard from above. E ... Even if the sample bottle is turned upside down and hit violently from above, the toner does not fall off.

(5) Fixability A test image was formed on a printer with variable temperature, the initial density of 1.0 ± 0.3 was passed through a fixing roller, and then the tape of the fixed part was peeled off to obtain a Macbeth reflection densitometer. Was used to measure the decay rate of the concentration. Then, the temperature of the roller is 5 ℃
The temperature was raised every time and the temperature at which the fixing rate exceeded 90% (attenuation rate 10%) was defined as the fixing temperature, and evaluation was performed according to the following criteria. The speed of the fixing roller was 100 mm / sec and the nip width was 0.8 mm. ⊚: Fixing temperature is 110 ° C. or lower ◯: Fixing temperature is 120 to 130 ° C. ×: Fixing temperature exceeds 130 ° C.

The abbreviations used in the examples and comparative examples are as follows. Diol A: Polyoxypropylene- (2.0) -2,
2-bis (4-hydroxyphenyl) propane diol B: polyoxyethylene- (2.0) -2,2
-Bis (4-hydroxyphenyl) propane

Examples 1 to 3 terephthalic acid, diol A and diol B in the amounts shown in Table 1
And ethylene glycol were placed in a reaction vessel equipped with a distillation column. Further, 0.05 part by weight of antimony trioxide as a catalyst was added to all the acid components, the internal temperature was kept at 250 ° C., the stirring speed was kept at 120 rpm, and the esterification reaction was carried out under normal pressure for 5 hours. 1.0 mm over 30 minutes in the system
The pressure was reduced to Hg, the internal temperature was kept at 260 ° C., and the condensation reaction was carried out while distilling ethylene glycol. The end point of the condensation reaction was set at 3 points of 1 hour, 2 hours and 3 hours, and 3 points of the corresponding resins R-1, R-2 and R-3 were set.
Got seeds. Table 1 shows the measurement results of the composition and physical properties of the obtained resins R-1, R-2 and R-3.

Carbon black (# 4 manufactured by Mitsubishi Kasei Co., Ltd.) was added to 94% by weight of the obtained resins (R-1 to R-3).
0) 5% by weight, charge control agent (Orient Chemical Industry Co., Ltd.)
Bontron S-34) 1% by weight was added and premixing was performed using a Henschel mixer, and then an internal mixer was used to obtain a temperature of 150 ° C. and a rotation speed of 65 rp.
Melt kneading was performed at m. After the obtained melt-kneaded product was cooled to room temperature, it was roughly pulverized using a hammer mill and pulverized to 15 μm or less using a jet mill. Then, classify to a particle size of 5 to 15 μm using an air classifier,
Toners T-1 to T-3 were obtained. Obtained toner (T-1
To T-3) were used to evaluate blocking resistance and fixability, and the results are shown in Table 1. From Table 1, resin R-1
-R-3 had a low softening temperature and Tg of more than 50 ° C., and the toners obtained by using these resins were good in both blocking resistance and fixability.

[0031]

[Table 1]

Example 4 Polymerization charge composition was set as shown in Table 2 and the softening temperature was 115 ° C.
A resin R-4 was obtained by performing the same operation as in Example 1 except that the reaction was terminated at a polymerization degree such that. Table 2 shows the measurement results of the composition and physical properties of the obtained resin R-4.

Using the resin R-4 obtained,
Toner T-4 was obtained in the same manner as in 3. The toner T-4 thus obtained was used to evaluate blocking resistance and fixability, and the results are shown in Table 2. Table 2 shows that the resin R-4 achieved a high Tg at a low softening temperature by using a specific aromatic diol in combination, and also had good blocking resistance and fixability.

[0034]

[Table 2]

Comparative Examples 1 to 4 Resins R-5 to R-8 were obtained in the same manner as in Example 4, except that the composition for polymerization was as shown in Table 3. Table 3 shows the measurement results of the composition and physical properties of these resins.

Using the obtained resins R-5 to R-8, toners T-5 to T-8 were obtained in the same manner as in Examples 1 to 3. The toners T-5 to T-8 thus obtained were used to evaluate blocking resistance and fixability, and the results are shown in Table 3. From Table 3, since (1) the resin R-5 has a small amount of the aromatic dicarboxylic acid used, the Tg is 4 even if the polymerization is advanced to a predetermined viscosity.
As low as 1 ° C., when used as a toner, blocking resistance is poor. (2) Resin R-6 has a high Tg of 81 ° C. and has good blocking resistance, but the fixability and melt fluidity are lowered. (3) Resin R-7 is a diol A as an aromatic diol.
It was a case where only the above was used, and it took 10 hours at the reaction temperature of 245 ° C. until the target characteristic value was obtained, and the productivity was low. (4) Resin R-8 is a diol B as an aromatic diol.
It was found that only 10 mol% of all the acid components was used, and the desired degree of polymerization was obtained, but the Tg was lowered and the blocking resistance was poor.

[0037]

[Table 3]

[0038]

As described above, the polyester resin for toner according to the present invention is obtained by condensing and polymerizing a specific aromatic diol in the polymer to obtain blocking resistance, melt fluidity, and low temperature fixability. And is useful as a toner resin for full-color, high-speed copying machines and high-speed printers.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichi Nagai 2-1, 4-Ushikawa-dori, Toyohashi-shi, Aichi Sanryo Rayon Co., Ltd. Toyohashi Plant

Claims (1)

[Claims] 1. A dicarboxylic acid component containing (a) 60 mol% or more of an aromatic dicarboxylic acid based on all acid components,
(B) a diol component containing 5 mol% or more of an aromatic diol represented by the following formula (I) with respect to the total acid component; and (c)
A polyester resin comprising a diol component containing 5 mol% or more of an aromatic diol represented by the following formula (II) with respect to all acid components, having a softening temperature of 90 to 130 ° C. and a glass transition point Tg of 50 to A polyester resin for toner, which has a temperature of 80 ° C. [Chemical 1] [Chemical 2]