JPH103182A - Polyester resin for full color toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a superior filming performance without melt-sticking to blades, and impairing sharp-melt property, color-developing performance, fixability, and blocking resistance as the full color toner by using a specified polyester resin. SOLUTION: This polyester resin is made from aromatic diol components represented by the formula R1 being a <=3C alkylene group and each of (m) and (n) being a natural number}, and this resin has at least one peak or shoulder in the region of molecular weight <=2500 in a molecular weight distribution measured by the gel permeation chromatography, and a content of the component up to the start point of the peak or the shoulder in the molecular weight distribution is <=20weight%, and the resin has a glass transition point of 55 deg.C-75 deg.C, thus permitting the obtained binder resin of the color toner to be prevented from melt attaching to the blades and enhanced in filming performance.

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 binder resin of a dry full-color toner used for developing an electrostatic image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like. More specifically, the present invention relates to a polyester resin for a full-color toner having excellent sharp melt properties, coloring properties, fixing properties and blocking resistance, and having excellent filming properties without blade fusion.

[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. Fixing is performed by directly fixing the toner image obtained by development on the photoconductive photoreceptor or the electrostatic recording medium, or by transferring the toner image on paper or film and then fixing it on a transfer sheet. Done. The fixing of the toner image is performed by contact with solvent vapor, pressurization and heating, and the heating method includes a non-contact heating method using an electric oven and a pressure heating method using a pressure roller.

On the other hand, in order to obtain a full-color image, in the above-described developing step, toner of three to four colors is adhered to transfer paper, and then, in a fixing step, the toner of each color is melted and mixed to form a color and fixed. There must be.

[0004] For this reason, binder resins for full-color toners are required to be resins having good mixing properties in the fixing step, excellent in sharp meltability, excellent coloring properties and fixability to paper and OHP. Usually, polyester resins are used. It is used.
Further, there is a demand for use as a non-magnetic one-component toner or a two-component toner requiring long-term durability, and a binder resin having a resin strength that does not cause fusion of the toner to a blade or filming occurs. Is being requested.

[0005]

In such a binder resin for a full-color toner, a method of reducing the molecular weight and the softening temperature of the resin has been adopted in order to impart sharp meltability and fixability. Such a binder resin has a problem that since the resin strength is impaired, fusion or filming of the toner is likely to occur. In order to prevent such blade fusion and filming of the toner, a method of introducing a crosslinking agent into a binder resin or increasing the glass transition temperature of the resin has been used. However, even with such a binder resin, sufficient strength cannot be imparted, and the occurrence of toner blade fusion and filming cannot be sufficiently solved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and has an object to impair the sharp melt property, color forming property, fixing property, and blocking resistance of a full-color toner. Another object of the present invention is to provide a polyester resin as a binder resin capable of obtaining a full-color toner having excellent filming properties without causing blade fusion.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the problems of the conventional binder resin as described above, and as a result, have found that a specific polyester resin can achieve the object. This has led to the invention. That is, the polyester resin for a full-color toner of the present invention is a polyester resin comprising an acid component containing a dicarboxylic acid as a main component and a diol component containing an aromatic diol represented by the following general formula (1). In the molecular weight distribution in the chromatography, there is at least one peak or shoulder in a region having a molecular weight of 2500 or less, and the content ratio of a component having a molecular weight of 20% or less at the starting point of the peak or shoulder among the peaks or shoulders is the maximum. % By weight or less and a glass transition temperature of 5
The temperature is 5 to 75 ° C.

[0008]

Embedded image

(In the formula, R1 is an alkylene group having 3 or less carbon atoms, and m and n are natural numbers.) The polyester resin for a full-color toner of the present invention has a glass transition temperature depending on the resin composition of the polyester resin. By adjusting the content within a specific range, imparting resin strength, and reducing the content of a specific low molecular weight component, a full color toner having excellent filming properties without blade fusion as a toner binder resin. What you can get.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The dicarboxylic acids (a) constituting the polyester resin of the present invention include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, phthalic acid, sebacic acid, isodecyl succinic acid, maleic acid and fumaric acid. And aliphatic dicarboxylic acids such as adipic acid and their lower alkyl esters or acid anhydrides. Examples of the lower alkyl esters of these dicarboxylic acids include monomethyl ester, monoethyl ester, dimethyl ester, diethyl ester and the like. Among them, terephthalic acid, isophthalic acid, adipic acid and lower alkyl esters thereof are preferred. These dicarboxylic acids can be used alone or in combination of two or more. In the present invention, the dicarboxylic acid (a) adjusts the glass transition temperature of the polyester resin and improves the blocking resistance, fusing property, filming property and fixing property of the toner. It is preferably contained in the range of 100 mol%, more preferably 90 to 10%.
It is in the range of 0 mol%, more preferably in the range of 95 to 100 mol%.

In particular, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid increase the glass transition temperature of the polyester resin, impart resin strength, and improve the toner's blocking resistance, blade fusing property, and filming property. And its hydrophobicity is also effective in improving the moisture resistance of the toner. Therefore, the aromatic dicarboxylic acid needs to be at least 50 mol% based on the total acid components,
Preferably it is in the range of 60 mol% or more. Among them, terephthalic acid-based ones are effective in increasing the glass transition temperature of the binder resin, and isophthalic acid-based ones are effective in increasing the reactivity, so that it is preferable to use them by changing the use balance depending on the purpose. . On the other hand, an aliphatic dicarboxylic acid such as adipic acid greatly affects the fixing property and blocking resistance of the toner. Therefore, it is necessary to use these properties in consideration of these properties.
It is preferable to use it in a range of 0 mol% or less.

In the present invention, a trivalent or higher polyhydric carboxylic acid or a trivalent or higher polyhydric alcohol (b) can be used as a component constituting the polyester resin, if necessary. The trivalent or higher polycarboxylic acid or the trivalent or higher polyhydric alcohol (b) imparts resin strength to the polyester resin and adjusts the molecular weight and molecular weight distribution. Performance can be improved. Trivalent or higher polycarboxylic acids include trimellitic acid, pyromellitic acid,
2,4-cyclohexanetricarboxylic acid, 2,5,7-
Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid,
Examples thereof include 1,2,7,8-octanetetracarboxylic acid and acid anhydrides thereof. Examples of the trihydric or higher polyhydric alcohol include sorbitol, 1,2,3,6-hexanetetralol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane Triol, 1, 2,
5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like. Among them, trimellitic acid and its acid anhydride, pentaerythritol, and trimethylolpropane are preferred. These trivalent or higher polycarboxylic acids or 3
The polyhydric alcohol (b) having a valency or higher can be used alone or in combination of two or more.

In the present invention, a trivalent or higher polyhydric carboxylic acid and / or a trivalent or higher polyhydric alcohol (b)
Is preferably used in a range of 30 mol% or less, more preferably in a range of 0 to 10 mol%, more preferably in a range of 0 to 5 mol%, based on the total acid component. When the polyvalent carboxylic acid having a valency of 3 or more and / or the polyhydric alcohol (b) having a valency of 3 or more exceeds 30 mol%, the melt viscosity of the polyester resin becomes high, and the fixing property and the color developing property of the toner decrease. To do that.

In the case where the polyester resin of the present invention contains such a crosslinking unit as a constituent unit, it does not form a highly crosslinked structure,
It is preferable that the polyester resin be formed so as to suppress the gelling of the polyester resin as much as possible and to form a structure in which a part thereof is slightly crosslinked or a branched structure. For this reason, when the polyester resin does not contain a gel component or is a binder resin having a gel fraction of an extremely low range of 5% by weight or less, the resin strength is imparted without lowering the sharp melt property. This is preferable in that the balance between toner fixability, color developability and image stability can be improved. If the gel fraction of the polyester resin exceeds 0.5% by weight, the color development of the toner tends to be inferior, more preferably 2% by weight or less, more preferably 1% by weight or less.

Further, the aromatic diol (c) represented by the general formula (1) constituting the polyester resin of the present invention is:
It raises the glass transition temperature of the polyester resin, increases the resin strength, and reduces the low molecular weight components of the polyester resin. It improves the blocking resistance, fusing property, and filming property of the toner, as well as the reactivity of the resin. Is a component for controlling As the aromatic diol (c),
For example, polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2.3) -2,2-bis (4-hydroxyphenyl) propane, polyoxy Ethylene- (2.8)-
Bisphenol A derivatives to which ethylene oxide is added, such as 2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene- (3.0) -2,2-bis (4-hydroxyphenyl) propane, 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-
Bisphenol A derivatives to which propylene oxide has been added, such as hydroxyphenyl) propane and polyoxypropylene- (3.0) -2,2-bis (4-hydroxyphenyl) propane; and these may be used alone or in combination of two or more. It can be used in combination.

In particular, bisphenol A derivatives to which propylene oxide has been added are preferred in order to increase the glass low temperature of the polyester resin and to impart resin strength. In order to reduce the low molecular weight components of the polyester resin, ethylene oxide is preferred. An added bisphenol A derivative is preferred. Among them, polyoxypropylene (n) -2,2-bis (4-hydroxyphenyl) propane satisfying 2.1 ≦ n ≦ 2.5, and 2.0 ≦ n ≦ 3.
Polyoxyethylene- (n) -2,2-bis (4-hydroxyphenyl) propane, which is 0, is preferred.

Since these aromatic diols (c) are liable to undergo thermal decomposition at high temperatures, when used in combination with a dicarboxylic acid that requires high reactivity, the aromatic diol (c) has a content of 20 to 20% based on the total acid components.
It is preferably used in the range of 110 mol%, more preferably in the range of 25 to 105 mol%. this is,
If the amount of the aromatic diol (c) is less than 20 mol%, the glass transition temperature of the polyester resin tends to decrease, and the blocking resistance, fusing property and filming property of the toner tend to decrease. On the other hand, when the amount of the aromatic diol (c) exceeds 110 mol%, the reactivity is remarkably reduced and the reaction does not proceed to a desired degree of polymerization.
In particular, in order to balance the glass transition temperature of the polyester resin and the content of the low molecular weight component, and to improve the fusing property and filming property of the toner, the bisphenol A derivative to which ethylene oxide has been added is converted into a total acid component. In the range of 2 to 80 mol%, more preferably 5 to 7 mol%.
The content of the bisphenol A derivative to which propylene oxide is added is 0 to 70 mol% based on the total acid component.
It is preferably in the range of mol%, more preferably in the range of 0 to 60 mol%.

The aliphatic diol (d) constituting the polyester resin of the present invention improves the polycondensation reaction rate of the resin, and includes, for example, ethylene glycol, neopentyl glycol, propylene glycol, butanediol, polyethylene glycol, 1,2-propanediol, 1,4-butanediol, diethylene glycol,
Examples include triethylene glycol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and the like, and these can be used alone or in combination of two or more. Among them, ethylene glycol, neopentyl glycol, and butanediol are preferable from the viewpoint of fixing property as a toner. The aliphatic diol (d) is preferably used in a range of 10 to 110 mol%, more preferably in a range of 15 to 105 mol%, based on all acid components. If the aliphatic diol (d) is less than 10 mol%, the reactivity is remarkably reduced and the reaction does not proceed to a desired degree of polymerization, and if it exceeds 110 mol%, the glass transition temperature and the resin strength of the polyester resin decrease. , The blocking resistance, fusing property, and filming property of the toner tend to decrease.

The polyester resin for a full-color toner of the present invention having the above-mentioned structure has a molecular weight of 25 based on the molecular weight distribution determined by gel permeation chromatography.
The peak or shoulder having at least one peak or shoulder in the region of not more than 00, and the content of a component having a molecular weight of not more than the starting point of the peak or shoulder having the largest molecular weight among the peaks or shoulders is in a range of not more than 20% by weight, Glass transition temperature 55
It needs to be in the range of ℃ 75 ° C. This is because if the glass transition temperature is less than 55 ° C., the blocking resistance, the fusing property, and the filming property of the toner decrease, and if the glass transition temperature exceeds 75 ° C., the fixing property of the toner decreases. The temperature is in the range of 58 to 70C, more preferably 60 to 70C.
It is in the range of 68 ° C. When the content of the component having a molecular weight of not more than the peak or the starting point of the shoulder having the maximum molecular weight in the region having a molecular weight of 2500 or less exceeds 20% by weight, the glass transition temperature of the polyester resin is sufficiently increased to impart resin strength. This is because even if it does, the occurrence of blade fusion and filming of the toner cannot be sufficiently suppressed, and is preferably in the range of 18.5% by weight or less, more preferably in the range of 17% by weight or less. .

As shown in FIG. 1 or 2, in the present invention, the peak (P) in the molecular weight distribution is an upward projection having a maximum value, and the shoulder (S) does not have a maximum value. It is a protrusion in the left-right direction. The start point (Ps) of the peak is a portion indicating the minimum value on the high molecular weight side of the peak, and the start point (Ss) of the shoulder is the value of the slope (detection) from the baseline data in the data detection sensitivity. (Sensitivity ΔH / retention time ΔT) is 0.0
This is a portion where the voltage becomes 5 mV / min or more. Furthermore, in the present invention, the measurement of the molecular weight distribution by gel permeation chromatography was performed using gel permeation chromatography (HCL-8200 manufactured by Tosoh Corporation) under the following measurement conditions.

Column conditions: G4000Hx1 × G2000Hx1 Oven temperature: 40 ° C. Eluent: tetrahydrofuran Flow rate: 1 ml / min Sample concentration: 0.4% by weight Injection volume: 100 μl Detector: RI

The polyester resin for a full-color toner of the present invention has a weight average molecular weight of 4,000 to 4,000 as determined by gel permeation chromatography.
20,000, softening temperature 90-130 ° C, acid value 20m
It is preferably in the range of gKOH / g or less. If the weight average molecular weight of the polyester resin is less than 4,000, the resin strength tends to decrease, and the fusing property and filming property of the toner tend to decrease. This is because the property tends to decrease, and more preferably 4500 to 1970
0, more preferably 5000 to 18500
Range. Further, the softening temperature of the polyester resin is 9
If the temperature is lower than 0 ° C., the resin strength is reduced, and the fusion property of the toner,
When the filming temperature exceeds 130 ° C., the sharp melting property and the fixing property of the toner tend to decrease, more preferably in the range of 95 to 128 ° C., and still more preferably in the range of 90 to 120 ° C. C is the range.
Further, the acid value of the polyester resin is 20 mgKOH / g
If the ratio exceeds the range, it is difficult to control the charge amount of the toner, and the charge stability tends to decrease.
KOH / g or less, more preferably 15 mg
KOH / g or less.

The production of the polyester resin for a full-color toner of the present invention is not particularly limited, and it can be produced by a commonly used method. For example, the above polymerization components (a) to (d) are charged into a reaction vessel,
An esterification reaction or a transesterification reaction is performed by heating the mixture. 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. Thereafter, a polymerization reaction is subsequently performed. At this time, polycondensation is performed while distilling and removing the diol component under a vacuum of 150 mmHg 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 and the like can be used. The polymerization temperature and the amount of the catalyst are not particularly limited, and may be arbitrarily set as needed.

The polyester resin for a full-color toner of the present invention is used as a binder resin, together with a known colorant usually used as a full-color toner, a charge control agent, a release agent such as an olefin type, and a flow modifier such as silica. By mixing, kneading, pulverizing and classifying, a full-color toner can be obtained.

[0025]

The present invention will be described below in detail with reference to examples. In addition, the physical property of the polyester resin in an Example and a comparative example was measured by the following measuring methods. The weight average molecular weight was determined by gel permeation chromatography (HCL-820 manufactured by Tosoh Corporation) using tetrahydrofuran as a solvent.
0). The glass transition temperature (° C) was measured using a differential scanning calorimeter (manufactured by Shimadzu Corporation) at a heating rate of 5 ° C /
The contact point between the tangent of the endothermic curve near the glass transition temperature measured in minutes and the baseline was taken as the glass transition temperature. The acid value was measured by a titration method using a KOH solution. In the composition analysis, the resin was hydrolyzed with hydrazine and quantified by liquid chromatography.

The evaluation of the toner performance in Examples and Comparative Examples was performed according to the following method. Fixing ability The temperature was able to be freely changed, and the minimum fixing temperature to paper when printing at a printing speed of 20 sheets / min was measured using a full-color copying machine having a blade, and evaluated according to the following criteria. ：: Fixable at 120 ° C. or less. ：: Fixing is possible at 121 to 135 ° C. X: Fixing is not possible at 135 ° C or lower.

Blocking resistance 5 g of the toner is placed in a glass sample bottle, and the temperature is 50 ° C.
For 24 hours. Thereafter, the sample was cooled to room temperature, the state of aggregation was visually observed, and evaluated according to the following criteria. A: The toner is dispersed when the sample bottle is turned upside down. ：: Dispersed when the sample bottle was inverted and hit two or three times. ×: No dispersion occurs even if the sample bottle is turned upside down and hit twice or three times.

Filming property The temperature can be freely changed, and a full-color copying machine having a blade is used at a printing speed of 20 sheets / min.
The image and the state of contamination of the photoreceptor after printing 10,000 sheets were visually observed and evaluated according to the following criteria. A: No contamination of the image and the photoreceptor is observed. ：: Slight stain is recognized on the image or the photoreceptor. X: The image or the photosensitive member is significantly stained.

Fusing ability: The temperature can be freely changed, and a full-color copying machine having a blade is used at a printing speed of 20 sheets / min.
The state of fusion of the toner on the blade after printing of 10,000 sheets was visually observed and evaluated according to the following criteria. ：: No fusion was observed on the blade. ：: Some fusion was observed on the blade. X: The fusion on the blade is remarkable.

Image stability The temperature can be freely changed, and a full-color copying machine having a blade is used at a printing speed of 20 sheets / min.
After printing of 10,000 sheets, the density change of the obtained printed image was evaluated according to the following criteria. ：: Little change in image density was observed. ：: Image density is slightly reduced. D: The image density is significantly reduced.

Examples 1 to 14 According to the charge composition shown in Table 1, the monomer mixture was charged into a reaction vessel equipped with a distillation column. Further, 800 ppm of antimony trioxide was added to all the acid components, the temperature in the reaction system was maintained at 265 ° C., and the rotation speed of the stirring was maintained at 120 rpm.
After an hour, the reaction was terminated when no more water was distilled. Next, the temperature in the reaction system was maintained at 220 ° C., and the pressure was reduced over about 40 minutes until the degree of vacuum in the reaction vessel became 1.0 mmHg. The diol component was distilled out of the reaction system, and the condensation reaction was performed for 2 hours. When the desired softening temperature was reached, the pressure inside the reaction vessel was returned to normal pressure, and the polyester resin was taken out of the reaction vessel. Table 1 shows the composition analysis results of the obtained polyester resin, and Table 2 shows the measurement results of physical properties. Further, using a full-color toner using the obtained polyester resin as a binder resin, fixability, blocking resistance, filming property, fusing property, and image stability were evaluated. The results are shown in Table 2.

Comparative Examples 1 to 4 Polyester resins were obtained in the same manner as in the Examples except that the polymerization charge composition was changed as shown in Table 1. Table 1 shows the composition analysis results of the obtained polyester resin, and Table 2 shows the measurement results of physical properties. Further, using a full-color toner using the obtained polyester resin as a binder resin, fixability, blocking resistance, filming property, fusing property and image stability were evaluated. The results are shown in Table 2.

[0033]

[Table 1]

[0034]

[Table 2]

The abbreviations in the table represent the following compounds, respectively. TPA: terephthalic acid TMA: trimellitic anhydride NDCA: naphthalenedicarboxylic acid EG: ethylene glycol diol A: polyoxypropylene- (2.3) -2,
2-bis (4-hydroxyphenyl) propane diol B: polyoxyethylene- (2) -2,2-bis (4-hydroxyphenyl) propane CHDM: 1,4-cyclohexanedimethanol TMP: trimethylolpropane

[0036]

The polyester resin for a full-color toner according to the present invention has excellent filming properties, without impairing the sharp-melt properties, coloring properties, fixing properties and blocking resistance of a full-color toner, without fusing the toner blade. And a full-color toner.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a molecular weight distribution by gel permeation chromatography.

FIG. 2 is an explanatory diagram of a molecular weight distribution by gel permeation chromatography.

Claims (4)

[Claims] An acid component comprising a dicarboxylic acid as a main component,
A polyester resin comprising a diol component containing an aromatic diol represented by the following general formula (1), having at least one peak or shoulder in a region having a molecular weight of 2500 or less in a molecular weight distribution by gel permeation chromatography, A full-color toner, wherein the content of a component having a molecular weight equal to or less than the starting point of the peak or shoulder having a maximum molecular weight of the peak or shoulder is 20% by weight or less, and the glass transition temperature is 55 to 75 ° C. For polyester resin. Embedded image (Wherein, R1 is an alkylene group having 3 or less carbon atoms, m
And n are natural numbers. ) 2. A polyester resin comprising 70 to 100 mol% or more of dicarboxylic acid (a) with respect to all acid components, 0 to 30 mol% or less of trivalent or more polyvalent carboxylic acid with respect to all acid components, and And / or trihydric or higher polyhydric alcohol (b),
20 to 110 mol% of the aromatic diol (c) represented by the general formula (1) based on the total acid component,
The polyester resin for a full-color toner according to claim 1, wherein the polyester resin is composed of an aliphatic diol (d) in an amount of from about 110 mol%. 3. An aromatic diol (c) represented by the general formula (1) is a bisphenol A derivative to which 2-80 mol% of ethylene oxide is added based on the total acid component, and a bisphenol A derivative based on the total acid component. 3. The polyester resin for a full-color toner according to claim 1, comprising a bisphenol A derivative to which 0 to 70 mol% of propylene oxide is added. 4. A weight average molecular weight of 400 in the molecular weight distribution in gel permeation chromatography.
2. The polyester resin for a full-color toner according to claim 1, wherein the polyester resin has a softening temperature of 90 to 130 [deg.] C. and an acid value of 20 mgKOH / g or less.