JP3502459B2 - Polyester resin for toner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry toner used for developing an electrostatic image or a magnetic latent image in electrophotography, electrostatic recording or electrostatic printing. Related to useful polyester resins. More specifically, it is excellent in blocking resistance, low-temperature fixing property, non-offset property and strength, especially for high-speed copying machines and high-speed printers requiring low-temperature fixing property, and as a non-magnetic one-component toner requiring toner strength. The present invention relates to a useful polyester resin for a toner. 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 photoreceptor or an electrostatic recording medium is prepared by using a toner previously charged by friction. After development, it is fixed. For a magnetic latent image,
After the latent image on the magnetic drum is developed with toner containing a magnetic material, it is fixed. 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 the toner image 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. The toner used in the dry development method includes a one-component toner and a two-component toner. The two-component toner is first melt-kneaded with a resin, a colorant, a charge control agent, and other necessary additives, sufficiently dispersed, then coarsely pulverized, then finely pulverized, and classified into a predetermined particle size range. Manufactured. The one-component toner is similarly manufactured by adding magnetic iron powder in addition to the components of the two-component toner. [0003] Resin is the main component in the formulation of the toner, and thus controls most of the performance required for the toner. For this reason, the resin for the toner is 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 such as non-offset properties, good blocking resistance and good electrical properties are required. Epoxy resins, polyester resins, polystyrene resins, methacrylic resins, and the like are known as resins used in the production of toners, but styrene and (meth)
Acrylic acid ester copolymers have been used. However, polyester resins have attracted attention because they can be fixed at lower temperatures and have excellent PVC plasticizer resistance of the fixed toner images. On the other hand, as the performance of copying machines, printers and the like becomes higher, the performance required of the toner and resin for the toner used for them also changes depending on the type of the copying machine, the printer and the like. In particular, portable type small copiers that have recently become widespread are often used in ordinary households, have relatively low printing rates, and have a long mixing time for toner charging in the development process. In the meantime, the toner is excessively pulverized, and the particle diameter is easily reduced. For this reason, the charge amount of the toner changes, and the rate of change in the image density tends to increase. In addition, when used for home use, there is a problem with its maintenance. Further, some developing systems, such as a non-magnetic one-component system, have a system in which toner is strongly pressed against a developing roll to be charged. In such a system,
In the charging step, the toner is excessively pulverized, the particle diameter tends to be small, the charge amount of the toner changes, and the change rate of the image density tends to increase. [0005] In order to prevent such pulverization of the toner, it is necessary to improve the strength of the toner, and a polyester having a strength higher than that of a styrene resin or the like is required. Although it is preferable to use the resin as the resin for the toner, in the conventional polyester resin for the toner,
It has been difficult to satisfy the fixing property and the non-offset property as a toner and to provide a sufficient toner strength. The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a polyester resin for toner having excellent blocking resistance, low-temperature fixing property, non-offset property and strength. It is in. Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, a polyester resin containing a specific aromatic diol as a polymer component can achieve the object. And completed the present invention. That is, the polyester resin for a toner of the present invention comprises (a) a dicarboxylic acid component containing 60 mol% or more of an aromatic dicarboxylic acid with respect to the total acid component, and (b) a 1 to 1 total acid component.
70 mol% of the aliphatic glycol, (c) 50 to 90 mol% of the aromatic diol represented by the following formula (1) based on the total acid component, and (d) 5 to 50 mol of the total acid component. % Of a diol component containing an aromatic diol represented by the following formula (2) and (e) 16 to 30 mol% of 3
A polyester resin comprising a polyvalent carboxylic acid having a valency of 3 or more and / or a polyhydric alcohol having a valency of 3 or more, having a softening temperature of 90 to 140C and a glass transition point Tg of 50 to 80.
° C and a toughness index of 250 to 600 µm. [0007] (Where X is a number that satisfies 2 ≦ X ≦ 3). (In the formula, Y is a number satisfying 2 ≦ Y ≦ 3.) The aromatic dicarboxylic acid (a) constituting the polyester resin of the present invention is an aromatic dicarboxylic acid 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, diethyl isophthalic acid, dibutyl terephthalic acid, dibutyl isophthalic acid, and the like, 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 increases the Tg of the obtained resin, contributes to an improvement in blocking resistance, and has an effect on moisture resistance due to its hydrophobicity. Therefore, the aromatic dicarboxylic acid (a) must be contained in an amount of 60 mol% or more, preferably 70 mol% or more, based on all the acid components. Among them, terephthalic acid-based aromatic dicarboxylic acids are effective in increasing the Tg of the resin, and isophthalic acid-based aromatic dicarboxylic acids are effective in increasing the reactivity. preferable. In the present invention, other dicarboxylic acids may be used in combination with the above-mentioned aromatic dicarboxylic acids, if necessary. Other dicarboxylic acids include, for example, phthalic acid, sebacic acid, isodecyl succinic acid, fumaric acid, adipic acid and their monomethyl, monoethyl,
Examples thereof include dimethyl and diethyl esters, and acid anhydrides thereof. Since these other dicarboxylic acids greatly affect the fixing property and blocking resistance of the toner,
It is used in consideration of these properties, and is preferably 40 mol% or less, more preferably 30 mol%, based on the total acid components.
It is contained in the following range. In the present invention, the aliphatic diol (b) used as the diol component includes ethylene glycol, neopentyl glycol, 1,2-propylene glycol, 1,3-propylene glycol,
1,4-butanediol, 1,5-pentanediol,
1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and the like, and these may be used alone or in combination of two or more. Can be used.
Among them, ethylene glycol, neopentyl glycol, and 1,4-butanediol are preferred from the viewpoints of reactivity, fixing property, handleability, and the like. These aliphatic diols (b)
Has the effect of increasing the rate of polycondensation reaction, but if the amount of the aliphatic diol (b) is too large, the Tg and strength are reduced. Therefore, the content of the aliphatic diol is 1 to the total acid component. It is necessary to be in the range of 70 to 70 mol%, preferably 5 to 60 mol%, more preferably 10 to 50 mol%. The aromatic diol (c) represented by the formula (1) used in the present invention increases the Tg of the resin,
It is a component for controlling reactivity. Examples of the aromatic diol (c) include 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)
And -2,2-bis (4-hydroxyphenyl) propane and the like, and these can be used alone or in combination of two or more. The content of the aromatic diol (c) is 30 to 90 mol%, preferably 40 to 80 mol%, more preferably 50 to 70 mol%, based on the total acid components. This is because if the content is less than 30 mol%, the Tg of the resin tends to decrease, and the blocking property of the toner tends to decrease. Also, if it is used in an amount exceeding 90 mol%, the reactivity is remarkably reduced and the reaction does not tend to progress to a desired degree of polymerization. Further, the aromatic diol (d) represented by the formula (2) used in the present invention is a component which enhances the orientation of molecules, imparts strength to the resin, and improves the reactivity. As the aromatic diol (d), 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)
And propane. These can be used alone or in combination of two or more. Among them, from the viewpoint of high Tg, reactivity, handleability, etc., polyoxyethylene-
(2.0) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxyethylene- (2.3) -2,2-
Bis (4-hydroxyphenyl) propane is preferred.
The content of the aromatic diol (d) is 5
５０50 mol%, preferably 10-40 mol%, more preferably 15-35 mol%. this is,
If the content is less than 5 mol%, the molecular orientation tends to decrease and the strength tends to decrease. On the other hand, if it exceeds 50 mol%, it becomes difficult to form a slurry at the time of charging the raw material, and the productivity tends to decrease. In the present invention,
Component (c) described above as a component of the polyester resin
And (d) are used in combination to provide high reactivity and high Tg
In some cases, a polyester resin for toner with a good balance of fixing, fixing property and productivity can be obtained. The trivalent or higher polycarboxylic acid or the trivalent or higher polyhydric alcohol (e) used in the present invention.
Is a component for imparting a cross-linked structure to the polyester resin, which increases the Tg of the resin, imparts cohesiveness to the resin, and increases the offset resistance and strength. Examples of the trivalent or higher polycarboxylic acid include trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid,
1,2,4-naphthalenetricarboxylic acid, 1,2,5-
Examples include hexanetricarboxylic acid, 1,2,7,8-octanetetracarboxylic acid, and acid anhydrides thereof. In addition, as the polyhydric alcohols having 3 or more valences, sorbitol, 1,2,3,6-hexanetetralol, 1,1
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. These trivalent or higher polycarboxylic acids or trivalent or higher polyhydric alcohols (e) can be used alone or in combination of two or more. In the present invention, the content of the trivalent or higher polyhydric carboxylic acid and / or the trivalent or higher polyhydric alcohol (e) is in the range of 16 to 30 mol% with respect to all the acid components. Preferably it is in the range of 16 to 28 mol%. This is because if the content is less than 16 mol%, the offset resistance and strength of the toner tend not to be sufficiently improved. On the other hand, if it exceeds 30 mol%, the reaction of the crosslinked structure portion becomes preferential, and the strength of the resin tends to be impaired. The polyester resin for a toner of the present invention comprising the above-mentioned components has a softening temperature of 90 to 14.
0 ° C. and Tg must be 50 to 80 ° 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 reduced, so that the cohesive force of the resin is reduced and the offset resistance tends to be deteriorated. If it exceeds, the low-temperature fixability tends to be impaired, and it is preferably in the range of 95 to 135 ° C. If the Tg is lower than 50 ° C., the blocking resistance tends to decrease. On the other hand, if the Tg exceeds 80 ° C., the fixing property tends to decrease.
It is in the range of 5-70C. Further, in the polyester resin for a toner of the present invention, the toughness index needs to be in the range of 250 to 600 μm, preferably 300 to 550.
It is in the range of μm. This is because the toughness index is 250 μm
If it is less than 1, the strength of the toner is low, the toner is excessively pulverized during development in a copying machine or a printer, and the particle size is reduced,
This is because the charge amount of the toner tends to change, and the stability of the image density tends to be impaired. Also, 600 μm
If the ratio exceeds the range, the fixability as a toner tends to be impaired. In the present invention, the toughness index of the polyester resin is measured by the following method. (1) The crushed product of the polyester resin is sieved to a particle size of 1.
A 50 g sample having a normal distribution centered on 700 μm is prepared. (2) Finely pulverize 30 g of the prepared sample with a blender TR-BL manufactured by TriScience Corporation (scale: 10:30 seconds). (3) Weigh 20 g of the obtained finely pulverized product. (4) The sieve whose mass has been weighed is sifted to a sieve having a coarseness of 100 μm, 150 μm, 250 μm, 500 μm.
Assemble from below in the order of m, 710 μm, and 1000 μm. (5) 20 g of the weighed finely pulverized material is put into the uppermost portion (1000 μm) of the assembled sieve, and is placed in a micro-type electromagnetic vibration sieve M-2 manufactured by Tsutsui Rika Kikai Co., Ltd.
Vibration is applied for 0 minutes (scale 10). (6) Weigh the polyester resin remaining on each sieve. (7) The respective values are plotted on a semilogarithmic graph (cumulative weight of each mesh pass), and the particle size passing by 50% by weight is read from the graph and used as a toughness index. In the production of the polyester resin for a toner according to the present invention, the above-mentioned polymerization components (a) to (e) are charged into a reaction vessel and heated to raise the temperature to carry out an esterification reaction or a transesterification reaction. At this time, an esterification catalyst or a transesterification catalyst used in a normal esterification 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 carried out continuously.
The polymerization is carried out while distilling and removing 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 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. 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 needed. The effect of the addition of the silica powder is particularly remarkable when the Tg of the binder resin is low. But T
The effect of improving the anti-blocking property is not remarkable for a resin having a g of 40 ° C. or less. The present invention will be described in detail with reference to examples. The performance evaluation in Examples and Comparative Examples was performed using the following method. Softening temperature (° C) Using a flow tester (CFT-500) manufactured by Shimadzu Corporation, nozzle 1.0 mmφ × 10 mmL, load 30 kg
f, the temperature at which half of the sample flowed out under the conditions of a temperature rise of 3 ° C./min and a sample amount of 1.0 g was defined as a softening temperature (° C.). Tg (glass transition point) (° C.) The contact point between the tangent line of the endothermic curve near Tg and the base line when measured at a temperature rise of 5 ° C./min using a differential scanning calorimeter manufactured by Shimadzu Corporation was defined as Tg. . Composition analysis The resin was hydrolyzed with hydrazine and quantified by liquid chromatography. A test image is formed on a non-magnetic one-component printer in which the fixing temperature is variable. After passing a portion having an initial density of 1.0 ± 0.3 through a fixing roller, the fixing portion is bent, and a load of 10 kg is applied for 1 minute. The tape was peeled from that portion, and the density decay rate was measured using a Macbeth reflection densitometer. Next, the temperature of the roller is increased every 5 ° C., and the fixing rate is 90% (the attenuation rate is 10%).
%) Was taken as the fixing temperature. The speed of the fixing roller was 100 mm / sec, and the nip width was 0.8 mm. Printing durability Evaluation After copying 5,000 sheets using a non-magnetic one-component copying machine, changes in images were visually observed and evaluated according to the following criteria. A: A clear image was obtained from first to last. B: Image density slightly changed on the way, but good throughout. C: A good image was obtained up to 1000 copies. D: Image density was reduced from the beginning. The abbreviations used in the examples and comparative examples represent the following. Diol A: polyoxypropylene- (2.0) -2,
2-bis (4-hydroxyphenyl) propanediol B: polyoxyethylene- (2.0) -2,2
-Bis (4-hydroxyphenyl) propane. Examples 1 to 7 Raw materials having the charged compositions shown in Table 1 were charged into a reaction vessel equipped with a distillation column. Further, 0.08 parts by weight of dibutyltin oxide as a catalyst was added to all the acid components, and the esterification reaction was carried out at normal pressure for 5 hours while maintaining the internal temperature at 260 ° C. and the stirring rotation speed at 200 rpm. The pressure in the inside was reduced to 1.0 mmHg over 30 minutes, the internal temperature was maintained at 240 ° C., and a reaction was carried out for 2 hours while distilling ethylene glycol to obtain a polyester resin. Table 2 shows the measurement results of the composition and physical properties of the obtained polyester resin. To 94% by weight of the obtained polyester resin, 5% by weight of carbon black (# 40 manufactured by Mitsubishi Kasei) and 1% by weight of a charge control agent (Bontron S-34 manufactured by Orient Chemical Industries) were added, and a Henschel mixer was added. After performing premixing using an internal mixer, the temperature was adjusted to 1 using an internal mixer.
Melt kneading was performed at 70 ° C. and a rotation speed of 65 rpm. After cooling the obtained melt-kneaded product to room temperature, it was roughly pulverized using a hammer mill, and pulverized to 22 μm or less using a jet mill. Then, the particle size was 5 using an air classifier.
The toner was obtained by classifying the toner into a particle size of about 22 μm. Using the obtained toner, the fixing temperature was measured and printing durability was evaluated. The results are shown in Table 2. [Table 1] [Table 2] Comparative Examples 1 to 5 Polyester resins were obtained in the same manner as in the Examples except that the polymerization charge compositions were as shown in Table 3. Table 4 shows the measurement results of the composition and physical properties of these resins. Using the obtained polyester resin, a toner was formed in the same manner as in the examples. Using the obtained toner, the fixing temperature was measured and the printing durability was evaluated. The results are shown in Table 4. In Comparative Example 1, the polyester resin having the desired viscosity could not be obtained because the polymerization reaction did not proceed sufficiently. In Comparative Example 2, the reaction proceeded rapidly and the resin could not be taken out. [Table 3] [Table 4] As described above, the polyester resin for a toner of the present invention is obtained by condensation polymerization using a specific aromatic diol in a polymer to provide anti-blocking properties, low-temperature fixing properties, and non-blocking properties. Excellent offset and strength,
In particular, it is useful as a non-magnetic one-component toner for high-speed copying machines and high-speed printers requiring low-temperature fixing properties, and as a non-magnetic one-component toner requiring toner strength.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-128368 (JP, A) JP-A-6-110251 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (1)

(57) [Claim 1] (a) a dicarboxylic acid component containing 60 mol% or more of an aromatic dicarboxylic acid based on the total acid component;
(B) 1 to 70 mol% of an aliphatic glycol with respect to the total acid component, (c) 50 to 90 mol% of an aromatic diol represented by the following formula (1) with respect to the total acid component, and (d) A) a diol component containing an aromatic diol represented by the following formula (2) in an amount of 5 to 50 mol% based on the total acid component; A polyester resin comprising a polyvalent carboxylic acid and / or a trihydric or higher polyhydric alcohol, having a softening temperature of 90 to 140C, a glass transition point Tg of 50 to 80C, and a toughness index of 250.
A polyester resin for a toner having a thickness of from 600 to 600 μm. Embedded image (In the formula, X is a number satisfying 2 ≦ X ≦ 3.) (Where Y is a number satisfying 2 ≦ Y ≦ 3)