JPH07160045A - Polyester resin for toner - Google Patents

Abstract

PURPOSE:To improve fixing property, non-offset property, blocking resistance, and electric characteristic, by constituting ester resin for toner of a specific polymer component, and letting it to have a specific physical property. CONSTITUTION:This polyester resin for toner is constituted of dicarboxylic acid component (a) containing at least one sort of aromatic dicarboxylic acid or the low class alkylester, at least one sort of component (b) of polyhydric alcohol over trivalent, and diol component (c) containing at least one sort of aromatic diol shown in the formula. In the formula, R is alkylene group of carbon number under 3, X and Y are the numbers satisfying 2<=X+Y<=7, and this is a polymer constituted of the component (a) of over 60mol% against the total carboxylic acid component in the polyester, the component (b) of 0.5-50mol% against the total acid component, and the component (c) of 20-80mol% against the total acid component. The softening temperature is 90-170 deg.C, the glass transition point is 50-70 deg.C, the acid value is 0.5-10mgKOH/g, and the gel portion rate is 1.5-20%.

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 charge image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing and the like. The present invention relates to a polyester resin for toner, which has good low-temperature fixability, non-offset property and blocking resistance, and excellent electrical properties.

[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 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. Therefore, 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. Epoxy resins, polyester resins, polystyrene resins, methacrylic resins and the like are known as resins used in the production of toners, but for pressure-bonding and heat-fixing methods, a copolymer of styrene and (meth) acrylic acid ester is mainly used. Has been used.
However, polyester resins are attracting attention because they can be fixed at a lower temperature and the fixed toner image has excellent resistance to PVC plasticizer.

Polyester resins are produced by directly esterifying a divalent carboxylic acid and a diol, or by transesterifying a lower alkyl ester of a divalent carboxylic acid and a diol, followed by a condensation reaction. In the resin, in order to impart anti-offset property in the fixing step and obtain good electric characteristics, JP-A 1-3
As proposed in 07767, it is effective to co-condense trihydric or higher alcohols to have a crosslinked structure. However, a toner using a conventional polyester resin obtained by co-condensing a trihydric or higher alcohol has a drawback that the image quality changes depending on humidity because of insufficient moisture resistance, and its improvement is strongly desired. It was

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester resin for toner, which has good fixability, non-offset property, anti-blocking property, and excellent electrical characteristics, that is, humidity dependence of image quality is small. To do.

[0007]

Means for Solving the Problems As a result of intensive investigations aimed at achieving the above-mentioned object, the present inventors have found that a polyester resin composed of a specific polymer component and having specific physical properties has its purpose. The inventors have found what can be achieved and completed the present invention. That is, the present invention relates to (a) a dicarboxylic acid component containing at least one kind of aromatic dicarboxylic acid or a lower alkyl ester thereof, (b) at least one kind of polyhydric alcohol having 3 or more valences, and (c) the following formula (I ) A diol component containing at least one aromatic diol represented by the formula (a), wherein the component (a) is 60 mol% or more based on the total carboxylic acid components in the polyester, and the component (b) is the total acid component. On the other hand, it is a polymer having 0.5 to 50 mol%, the component (c) is 20 to 80 mol% with respect to the total acid component, and the softening temperature is 90 to 170 ° C. and the glass transition point Tg.
(Hereinafter, abbreviated as Tg) is 50 to 70 ° C., acid value is 0.5 to 10 mgKOH / g, and gel fraction is 1.5 to 20.
% Of polyester resin for toner.

[0008]

[Chemical 2]

The aromatic dicarboxylic acid or lower alkyl ester (a) thereof used in the present invention is selected from aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid and lower alkyl esters thereof. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include, for example, dimethyl terephthalic acid, dimethyl isophthalic acid, diethyl terephthalic acid, diethyl isophthalic acid, dibutyl terephthalic acid, dibutyl isophthalic acid, etc., but in terms of cost and handling. Dimethyl terephthalic acid and dimethyl isophthalic acid are preferred.
The above aromatic dicarboxylic acids or lower alkyl esters thereof are used alone or in combination of two or more.
The aromatic dicarboxylic acid raises the Tg of the obtained resin, contributes to the improvement of blocking resistance, and is also effective in moisture resistance due to its hydrophobicity. Therefore, the aromatic dicarboxylic acid should be used in an amount of 60 mol% or more, preferably 70 mol% or more, based on the total acid components in the polyester. 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.

Examples of the trihydric or higher polyhydric alcohol (b) used in the present invention include sorbitol,
1,2,3,6-hexatetralol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol , 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like. The above-mentioned component (b) is used alone or as a mixture, and has the effect of imparting cohesiveness to the resin and enhancing offset resistance. Therefore, the trihydric or higher polyhydric alcohol (b) is 0.5
It is necessary to use in the range of -50 mol%, preferably 1-35 mol%. If the amount of the trihydric or higher polyhydric alcohol (b) used is less than 0.5 mol%, the offset resistance decreases,
On the contrary, if the amount used exceeds 50 mol%, the blocking resistance decreases, which is not preferable.

The aromatic diol (c) used in the present invention is represented by the above formula (I). As an example of the aromatic diol, polyoxyethylene-
(2.0) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene- (2.0) -2,2
-Bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -polyoxyethylene-
(2.0) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene- (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.
4) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane and the like,
These are used alone or in combination of two or more.
The aromatic diol (c) has an effect of increasing the Tg of the resin and thus has good blocking resistance, and also has an effect of improving moisture resistance due to its hydrophobicity. Therefore, the amount of the aromatic diol (c) used is in the range of 20 to 80 mol% with respect to the total acid component. This is because when the amount of the aromatic diol (c) used is less than 20 mol%, a sufficient effect cannot be obtained, and when it is used in excess of 80 mol%, the reactivity is extremely lowered and the productivity is deteriorated. . In the present invention, the amount of the aromatic diol (c) used is preferably in the range of 30 to 70 mol% and more preferably in the range of 45 to 65 mol% from the viewpoint of further improving the moisture resistance of the toner.

Further, in the present invention, a polymerization component other than the above may be used in combination within the range not impairing the object of the present invention depending on the required performance. Generally, a monomer known as a raw material for polyester may be used as long as the effect of the present invention is maintained. For example, as the dicarboxylic acid component, an aliphatic carboxylic acid such as sebacic acid, dodecenyl succinic acid, fumaric acid, adipic acid, and their monomethyl, monoethyl, dimethyl, diethyl ester, acid anhydride and the like can be used.

These aliphatic dicarboxylic acids and their lower esters affect the fixability and blocking resistance of the toner. That is, the blocking resistance is improved by using aromatic terephthalic acid or isophthalic acid,
Fixability is reduced. On the other hand, aliphatic sebacic acid and adipic acid improve the fixability, but bring about a decrease in Tg, so that the blocking resistance is deteriorated. In the case of an aliphatic dicarboxylic acid, this tendency is stronger as long-chain monomers are. Therefore, it is necessary to use these characteristics in consideration.

Further usable diol components are:
Aliphatic diols and aromatic diols other than those represented by the above formula (I). Examples of the aliphatic diol include ethylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,4-butanediol, polyethylene glycol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc. From the point of, ethylene glycol, neopentyl glycol,
The use of 1,4-butanediol is preferred.

The polyester resin for toner of the present invention having the above constitution has a softening temperature of 90 to 170 ° C., preferably 95 to 170, a Tg of 50 to 70 ° C., preferably 55 to 70 ° C., and an acid value. 0.5-10 mg KOH / g,
Preferably 1-10 mg KOH / g, gel fraction 1.5
It is necessary to be -20%, preferably 2-15%. This is because when the softening temperature of the polyester resin is lower than 90 ° C., the fixability is improved, but the cohesive force of the resin is extremely reduced, and sufficient non-offset properties cannot be obtained. This is because if it exceeds the range, the non-offset property is improved, but the fixability is extremely lowered. Also,
If the Tg of the polyester resin is less than 50 ° C, the blocking resistance is poor. On the other hand, if the Tg is more than 70 ° C, the blocking resistance is good, but the fixing performance is significantly reduced, and the acid value is 0.5 mgKOH / g. When it is less than 1, the dispersibility of the colorant is lowered, while when the acid value exceeds 10 mgKOH / g, the negative chargeability is increased, the humidity dependence of the charge is increased, and the image quality may change depending on the environment. become.
Further, if the gel fraction of the polyester resin is less than 1.5%, the offset resistance required for the toner cannot be obtained, and conversely, if the gel fraction exceeds 20%, the offset resistance becomes good, but fixing The sex becomes worse.

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 transesterification catalyst such as sulfuric acid, titanium tetrabutoxide, dibutyltin oxide, magnesium acetate, manganese acetate or the like used in a usual esterification reaction or transesterification reaction can be used. Then, water or alcohol generated in the reaction is removed according to a conventional method. After that, the polymerization reaction is continuously carried out.
Polymerization is carried out under a vacuum of 50 mmHg or less while distilling off the diol component.

In the polymerization, generally known polymerization catalysts such as titanium tetrabutoxide, dibutyl tin 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 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, with respect to the resin having Tg of 40 ° C. or less, the effect of improving the blocking resistance is not remarkable.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. The performance evaluations in Examples and Comparative Examples were 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) Acid value (mgKOH / g) The resin was heated and dissolved in benzyl alcohol and then cooled to 1
The titration was performed with a KOH benzyl alcohol solution of / 50N.

(4) Gel Fraction (%) 0.5 g of a sample was put in 50 ml of tetrahydrofuran and dissolved by heating at 70 ° C. for 3 hours, and then Celite (Johns).
-Manville Salees # 545) was filtered through a glass filter and 80 ° C. in a vacuum dryer.
The value obtained by dividing the weight when fully dried by the initial weight.

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

(6) Non-offset fixing temperature range (° C.) The toner is evenly sprinkled on the paper (initial density ID = 1.
0 ± 0.3), and pass through a temperature-variable fixing roller. Next, the tape is peeled off from the fixed portion and the density attenuation rate is obtained. When the temperature of the roller was raised, the temperature at which the fixing rate exceeded 90% was defined as the minimum fixing temperature. Further, the temperature at which the toner began to adhere to the heat roller when the temperature was further raised was taken as the high temperature offset start temperature. The area between the lowest fixing temperature and the high temperature offset start temperature was defined as the feasible area (non-offset fixing temperature range). The speed of the fixing roller is 100 mm /
The nip width was set to 8.0 mm and evaluated.

(7) Blocking resistance 5 g of toner was placed in a 50 ml glass sample bottle,
After being left in a high temperature bath at 50 ° C. for 50 hours, it was cooled to room temperature, and the degree of aggregation was evaluated by the following method.
In addition, in the present invention, it was judged that those having aggregation degrees A, B and C could be used. A. Toner drops just by turning the sample bottle upside down. B. The toner drops just by turning the sample bottle upside down and shaking it lightly. C. Toner drops when the sample bottle is turned upside down and tapped. D. The toner drops when the sample bottle is turned upside down and strong vibration is applied. E. Even if the sample bottle is turned upside down and strong vibration is applied, the toner does not fall off.

(8) Evaluation of image quality The image quality of the copy obtained under the following copying conditions was evaluated by visual judgment.

(A) Copying conditions 5 parts by weight of toner and 95 parts by weight of carrier were mixed, and a running test of 5,000 to 10,000 sheets was performed using a copying machine capable of changing the fixing temperature and speed.

(B) Visual judgment of image quality The following five steps were carried out. A. Very good. B. Are better. C. Some fog can be seen, but it does not hinder practical use. D. Fog is seen, which is a practical problem. E. Fog is severe and very inferior.

The abbreviations used in Examples and Comparative Examples represent the following. Diol A: Polyoxypropylene (2.3) -2,2
-Bis (4-hydroxyphenyl) propane diol B: polyoxyethylene (2.3) -2,2-
Bis (4-hydroxyphenyl) propane

Example 1 70 mol parts of terephthalic acid, 30 mol parts of isophthalic acid, 14 mol parts of trimethylolpropane, 50 mol parts of diol A and 56 mol parts of ethylene glycol were placed in a reaction vessel having a distillation column. Furthermore, 0.08 parts by weight of dibutyltin oxide which is a catalyst is added to all the acid components,
The inner temperature was kept at 260 ° C., the stirring rotation speed was kept at 200 rpm, and the esterification reaction was carried out under normal pressure for 5 hours. Then, the pressure in the reaction system was reduced to 1.0 mmHg over 30 minutes, and the internal temperature was adjusted to 24
While maintaining at 0 ° C., the condensation reaction was performed for 2 hours while distilling ethylene glycol to obtain a pale yellow transparent resin R-1. The measurement results of the composition and physical properties of the obtained resin are shown in Table 1.

[0032]

[Table 1]

Next, with respect to 94% by weight of the resin R-1 obtained, carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) was used.
5% by weight, charge control agent (manufactured by Orient Chemical Industry Co., Ltd.,
1% by weight of Bontron S-34) was premixed with a Henschel mixer, and then melt-kneaded using an internal mixer manufactured by Kurimoto Iron Works Co., Ltd. at 170 ° C. and 65 rpm. The melt-kneaded product was cooled to room temperature, roughly crushed with a hammer mill, and then pulverized with a jet mill to 22 μm or less. Then, the particle size was adjusted to 5 to 22 μm by using an air classifier manufactured by Nippon Pneumatic Co., Ltd. to obtain Toner T-1. Table 2 shows the evaluation results of Toner T-1. From Table 1 and Table 2, it is judged that when the resin R-1 is used as the toner, the fixing property, the blocking resistance and the image quality are good under various copying conditions.

[0034]

[Table 2]

Examples 2 to 3 Resins R-2 to R-3 were obtained in the same manner as in Example 1 except that the composition for polymerization was changed as shown in Table 3. Resin R
Table 4 shows the measurement results of the compositions and physical properties of the resins of −2 to R-3.
Shown in.

[0036]

[Table 3]

[0037]

[Table 4]

Next, the same operations as in Example 1 were carried out using the above resins R-2 to R-3 to obtain T-2 to T-3. Table 5 shows the evaluation results of the obtained toners T-2 to T-3. It can be seen from Tables 4 and 5 that when the resins R-2 to T-3 are used as the toner, the fixing property, the blocking resistance and the image quality are excellent under various copying conditions.

[0039]

[Table 5]

Examples 4 to 6 Resins R-4 to R-6 were obtained in the same manner as in Example 1 except that the composition for polymerization was changed as shown in Table 6. Resin R
Table 7 shows the results of the composition analysis and the resin physical properties of the resins Nos. -4 to R-6.

Next, the same operations as in Example 1 were carried out using the above resins R-4 to R-6 to obtain T-4 to T-6. Table 7 shows the evaluation results of the obtained toners T-4 to T-6. From Table 7, it can be seen that when the resins R-4 to R-6 are used as the toner, the image quality is good even under fixing conditions, blocking resistance and various copying conditions.

[0042]

[Table 6]

[0043]

[Table 7]

Comparative Examples 1 to 5 Resins R-7 to R-10 were obtained in the same manner as in Example 1 except that the composition for polymerization was as shown in Table 8. Table 9 shows the measurement results of the compositions and physical properties of the resins R-7 to R-10. The degree of polymerization of resin R-7 did not increase until the desired softening temperature was reached. In addition, resin R-1
In No. 1, gelation occurred during the esterification, the reaction could not be controlled, and the resin could not be taken out.

Next, the same operations as in Example 1 were carried out using the above resins R-7 to R-10 to obtain a toner. Table 9 shows the evaluation results of the obtained toners T-7 to T-10.

[0046]

[Table 8]

[0047]

[Table 9]

[0048]

The polyester resin for toner of the present invention is
It has the characteristics of low temperature fixability, non-offset and anti-blocking property, and low humidity dependence of image quality. Therefore, especially in electrophotography, electrostatic recording and electrostatic printing, electrostatic charge image or magnetic It is useful as a resin for dry toner used for developing a latent image.

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

Claims (1)

[Claims] 1. A dicarboxylic acid component containing at least one aromatic dicarboxylic acid or a lower alkyl ester thereof, (b) at least one trihydric or higher polyhydric alcohol, and (c) the following formula (I): A diol component containing at least one aromatic diol represented by the formula (a), wherein the component (a) is 60 mol% or more based on the total carboxylic acid component in the polyester, and the component (b) is based on the total acid component. 0.5 to 50 mol%, the component (c) is 20 to 80 mol% with respect to the total acid component, and the softening temperature is 90 to 170 ° C. and the glass transition point Tg is 50 to 70. ℃,
Acid value 0.5 to 10 mgKOH / g, gel fraction 1.5
Polyester resin for toner, characterized in that it is ˜20%. [Chemical 1]