JP3426007B2 - 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. A useful polyester resin. More specifically, the present invention relates to a polyester resin for toner having excellent low-temperature fixability, blocking resistance and offset resistance. 2. Description of the Related Art In a method for obtaining a permanent visual image from an electrostatic charge image, an electrostatic charge image formed on a photoconductive photoreceptor or an electrostatic recording medium is previously charged by a toner 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:
Fusion of toner images is performed by contact with solvent vapor, pressurization and heating. There are two types of heating methods: non-contact heating using an electric oven and pressure heating using a pressure roller. Recently, the latter is mainly used. [0003] Toner used in the dry development system includes 1
There are two-component toners and two-component toners. A two-component toner is first melt-kneaded with a resin, a colorant, a charge control agent, and other necessary additives and 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. [0004] Resin is the main component in the compounding of the toner and therefore controls most of the performance required for the toner. For this reason, the resin for the toner is required to have good dispersibility of the colorant in the melt-kneading step in the production of the toner, good pulverizability in the pulverizing step, and the like.
A variety of performances such as good offset properties, blocking properties, and good electrical properties are required. Epoxy resin, polyester resin,
Polystyrene resins, methacrylic resins and the like are known, but copolymers of styrene and (meth) acrylic acid esters have been mainly used for pressure bonding and heat fixing systems. But,
Polyester resins have attracted attention because they can be fixed at lower temperatures and have excellent PVC plasticizer resistance of the fixed toner images. [0005] However, since the solubility parameter (SP value) of the polyester resin with Teflon applied to the fixing roller is far from that of the styrene / acrylic resin, the polyester resin is sufficiently used for general low and medium speed machines. Although it is possible, if the temperature of the resin is lowered to accommodate a high-speed machine or a low-energy type copying machine, the cohesive force of the resin is reduced and the offset resistance is deteriorated. Generally, styrene and acrylic resins use PP wax or the like as an anti-offset agent. However, polyester resins have poor compatibility with PP wax, and PP wax is added during the toner production process. However, the dispersion does not work well, and it is difficult to provide sufficient offset resistance. In addition, the toner has a problem that the charging stability of the toner is impaired and the color tone of the toner image is deteriorated. . At present, the copying machine industry is in the direction of high speed and low energy, and there is a strong demand for the appearance of a resin which is fixed at a low temperature and has excellent offset resistance. SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyester resin for toner having excellent low-temperature fixability, blocking resistance and offset resistance. The present inventors have made intensive studies to achieve the above object, and as a result, a polyester resin containing a specific polypropylene polymer as a polymer component was added to the polyester resin. It has been found that the object can be achieved, and the present invention has been completed. That is, the present invention provides (a) a dicarboxylic acid component containing at least one kind of aromatic dicarboxylic acid or lower alkyl ester thereof, and (b) a trivalent or higher polycarboxylic acid and / or polyhydric alcohol or lower ester thereof. At least one kind, (c) a diol component containing at least one kind of aromatic diol represented by the following general formula (I), and (d) a weight average molecular weight Mw5.
It is composed of a polypropylene polymer having an ester bond-forming group of not more than 000, wherein the component (a) is at least 60 mol% with respect to all the acid components in the polyester, and the component (d) is 50% with respect to the total condensed polyester. % By weight of a polymer having a glass transition point Tg (hereinafter abbreviated as Tg) of 40 to 80 ° C. and a softening temperature of 85 to 170 ° C. is there. [0009] The aromatic dicarboxylic acid or its lower alkyl ester (a) used in the present invention comprises 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 aromatic dicarboxylic acid or lower alkyl ester thereof is
It is used alone or in combination of two or more. Aromatic dicarboxylic acids increase the Tg of the obtained resin, contribute to improvement of blocking resistance, and have an effect on moisture resistance due to its hydrophobicity. Thus, the aromatic dicarboxylic acid is
It is necessary to use at least 60 mol%, preferably at least 70 mol%, based on the total acid components. Among them, terephthalic acid has an effect of increasing the Tg of the resin, and isophthalic acid has an effect of increasing the reactivity. Therefore, it is necessary to change the use balance depending on the purpose. The trivalent or higher polyvalent carboxylic acid and / or polyhydric alcohol or lower ester (b) used in the present invention is obtained from trivalent or higher polyvalent carboxylic acid, polyhydric alcohol and lower ester thereof. It is the choice. Examples of trivalent or higher polycarboxylic acids include:
Trimellitic acid, pyromellitic acid, 1,2,4 cyclohexanetricarboxylic acid, 2,5,7 naphthalene tricarboxylic acid, 1,2,4 naphthalene tricarboxylic acid, 1,
Examples thereof include 2,5 hexanetricarboxylic acid, 1,2,7,8 octanetetracarboxylic acid, and acid anhydrides thereof. Examples of polyhydric alcohols and lower esters thereof 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 component (b) is used alone or in combination, and has an effect of increasing the Tg of the obtained resin.
It has the effect of imparting cohesiveness to the resin and increasing the offset resistance, and is preferably used in the range of 0.5 to 30 mol% based on all acid components. This is because a sufficient effect cannot be obtained if the component (b) is less than 0.5 mol%.
If the amount exceeds mol%, it is difficult to control the gelation during the production of the polyester resin, and the desired resin tends to be hardly obtained. The aromatic diol (c) used in the present invention is represented by the above general formula (I).
Examples of the aromatic diol include 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, etc., and these are used alone or in combination of two or more. You. Since the aromatic diol (c) has an effect of increasing the Tg of the resin, the blocking resistance is improved. The amount of the aromatic diol component (c) used is preferably not more than 80 mol% based on the total acid components.
If it is used in excess of mol%, the reactivity will be extremely reduced and the productivity will be impaired. In the present invention, the polypropylene polymer (d) containing an ester bond-forming group is used in the above-mentioned (a) to (c) in order to impart offset resistance to a conventional toner resin comprising a polyester resin. Polycondensate with components. The amount of the polypropylene polymer component (d) used is 50% by weight or less, preferably 3 to 40% by weight, based on the total condensed polyester, and the weight average molecular weight Mw thereof is 50,000 or less. , Preferably 200 to
It is in the range of 40,000. This is because when the amount of the polypropylene polymer (d) exceeds 50% by weight or the weight average molecular weight Mw exceeds 50,000, the dispersibility in the polyester resin is poor, or the amount of the remaining polypropylene polymer is low. It is inferior in dispersibility as toner,
This is because the charge stability is reduced and the color tone of the toner image is deteriorated. Also, a polypropylene polymer (d)
If the amount used is less than 3% by weight or the weight average molecular weight Mw is less than 200, the offset resistance tends not to be sufficiently imparted. Further, in the polypropylene polymer (d) used in the present invention, the above-mentioned (a) to (c)
It is necessary to have an ester bond forming group to react with the components. The ester bond forming group in the polypropylene polymer (d) is not particularly limited,
Acid-modified one or both ends of the polypropylene polymer,
For example, it is preferable to use one modified with maleic acid or the like.
A propylene-maleic acid copolymer obtained by copolymerizing maleic acid can also be used as the polypropylene polymer of the present invention. In the present invention, polymerization components other than those described above can be used in combination according to the required performance as long as the object of the present invention is not impaired. Generally, a monomer known as a raw material of a polyester resin may be used as long as the effects of the present invention are maintained. For example, as a dicarboxylic acid component, sebacic acid, isodecyl succinic acid, fumaric acid, aliphatic dicarboxylic acids such as adipic acid, and their monomethyl, monoethyl, dimethyl,
Diethyl ester and the like can be used in a range of 30 mol% based on all acid components. These aliphatic dicarboxylic acids and lower esters thereof affect the fixing property and the anti-blocking property of the toner. That is, when aromatic terephthalic acid or isophthalic acid is used, the blocking resistance is improved, but the fixability is lowered. Conversely, aliphatic sebacic acid and adipic acid improve the fixability, but lower the Tg, so that the blocking resistance decreases. This trend is
In the case of an aliphatic dicarboxylic acid, a longer-chain monomer is stronger. Therefore, it is necessary to use these characteristics in consideration. Further usable diol components include:
An aliphatic diol and an aromatic diol other than those represented by the above general formula (I). The aliphatic diol is preferably contained in a range of 20 mol% or more based on all the acid components, and examples thereof include ethylene glycol, neopentyl glycol, butanediol, polyethylene glycol, cyclohexanedimethanol, hydrogenated bisphenol A, and the like. The use of ethylene glycol, neopentyl glycol and butanediol is preferred from the viewpoint of fixability. The polyester resin for a toner of the present invention having the above constitution has a Tg of 40 to 75 ° C., preferably 50 to 75 ° C.
７５75 ° C. and a softening temperature of 85-170 ° C. This is because if the Tg is lower than 40 ° C., the fixing property is improved but the blocking resistance is significantly reduced. If the Tg is higher than 75 ° C., the blocking resistance is improved but the fixing property is lowered. is there. Further, when the softening temperature of the polyester resin is less than 85 ° C., the cohesion of the polymer itself is extremely reduced, so that the cohesion of the resin is extremely reduced. Gets worse. On the other hand, when the softening temperature is 17
If the temperature exceeds 0 ° C., the offset resistance tends to be in a preferable direction, but the melt mixing property is reduced and the color mixing property is reduced. In the production of the polyester resin for a toner according to the present invention, the above-mentioned polymerization components (a) to (d) 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 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 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 toner of the present invention, if necessary, an inorganic powder such as silica can be added to improve the blocking resistance. The effect of the addition of the silica powder is particularly remarkable when the Tg of the binder resin is low. The present invention will be described below in detail with reference to examples. In addition, the performance evaluation in an Example and a comparative example was performed using the following method. (1) Tg (glass transition point) (° C.) Using a differential scanning calorimeter manufactured by Shimadzu Corporation, and raising the temperature to 5 ° C.
The contact point between the tangent line of the endothermic curve near Tg and the baseline when measured at / g was defined as Tg. (2) Softening temperature (° C.) Flow tester (CFT-50, manufactured by Shimadzu Corporation)
Using 0), the temperature at which half of the sample flowed out under the conditions of a nozzle 1.0 mmφ × 10 mmL, a load of 30 kg, a temperature rise of 3 ° C./min, and a sample amount of 1.0 g was defined as a softening temperature (° C.). (3) Weight average molecular weight Mw Measured by GPC HCL-8200 manufactured by Tosoh Corporation. (4) Composition analysis The resin was hydrolyzed with hydrazine and quantified by liquid chromatography. (5) Polypropylene content Quantified by NMR. (6) Non-offset fixing temperature range (° C.) Spread toner uniformly on paper (initial density ID = 1.
0 ± 0.3) and passed through a temperature-variable fixing roller. Next, the tape is peeled from the fixing portion, and the density attenuation rate is obtained.
When the temperature of the roller was increased, the temperature at which the fixing rate exceeded 90% was defined as the minimum fixing temperature. The temperature at which the toner began to adhere to the heat roller when the temperature was further increased was defined as the high temperature offset start temperature. A region between the minimum fixing temperature and the high-temperature offset start temperature was defined as a fixable region (non-offset fixing temperature width). Fixing roller speed is 100
mm / min and the nip width was set to 8.0 mm for evaluation. (7) Blocking resistance 5 g of toner is placed in a 50 ml glass sample bottle.
After standing in a high-temperature bath at 50 ° C. for 50 hours, the mixture was cooled to room temperature, and the degree of aggregation was observed. The degree of aggregation was evaluated by the following method. In the present invention, those having the cohesion degrees A, B, and C were determined to be usable. A: The toner drops just by inverting the sample bottle. 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 lightly tapped. D: When the sample bottle is turned upside down and strong vibration is applied, toner drops. E: Even if the sample bottle is turned upside down and strong vibration is applied, the toner does not fall. The abbreviations used in the examples and comparative examples represent the following. Diol A: polyoxypropylene (2.3) -2,2
-Bis (4-hydroxyphenyl) propanediol B: polyoxyethylene (2.3) -2,2-
Bis (4-hydroxyphenyl) propane polypropylene C: Mw 10,000 polypropylene modified with maleic acid at both ends Polypropylene D: Mw 20,000 propylene-maleic acid copolymer (2% by weight based on total polypropylene)
Polypropylene E: Mw 2,000 polypropylene modified with maleic acid at one end of polypropylene Polypropylene F: Mw 60,000 propylene-maleic acid copolymer (3% by weight based on total polypropylene)
Example 1 Terephthalic acid, isophthalic acid, trimellitic acid, diol A and ethylene glycol in the amounts shown in Table 1 were charged into a reaction vessel equipped with a distillation column. Furthermore, a polypropylene polymer C (Mw 10,000) having a reactive group capable of forming an ester bond in an amount of 10% by weight based on the calculated synthetic polymer amount.
(Both ends of maleic acid are modified with maleic acid) and 0.03 parts by weight of dibutyltin oxide as a catalyst with respect to all the acid components, the internal temperature is maintained at 260 ° C., the stirring rotation speed is maintained at 200 rpm, and the pressure is reduced to normal pressure. For 5 hours. Thereafter, the inside of the reaction system was set to 1.0 mm over 30 minutes.
The pressure was reduced to Hg, the internal temperature was maintained at 240 ° C., and a condensation reaction was carried out for 2 hours while distilling ethylene glycol to obtain a pale yellow transparent resin R-1. The obtained resin R-1 had a softening temperature of 142 ° C. and a Tg of 59.1 ° C. Table 2 shows the results of the composition analysis and the physical properties of the obtained resin. [Table 1] [Table 2] Next, with respect to 94% by weight of the obtained resin R-1, carbon black (manufactured by Mitsubishi Kasei Kogyo Co., Ltd., # 4
0) 5% by weight, charge control agent (Orient Chemical Industry Co., Ltd.)
And Bontron S-34) were premixed with a Henschel mixer, and melt-kneaded at 170 ° C. and 65 rpm using an internal mixer manufactured by Kurimoto Tekko Co., Ltd. After cooling the melt-kneaded product to room temperature, it was roughly pulverized by a hammer mill, and then pulverized to 20 μm or less using a jet mill. Then, using an air classifier manufactured by Nippon Pneumatic Co., Ltd., a toner T-1 having a particle size of 5 to 20 μm was obtained. Table 3 shows the fixing test result and the blocking resistance test result of Toner T-1. [Table 3] As is clear from Table 3, the toner T-1
It can be seen that the offset resistance and the blocking resistance are good. Examples 2 to 3 Resins R-2 to R-3 were obtained in the same manner as in Example 1 except that the polymerization charge composition was changed as shown in Table 4. Resin R
Table 5 shows the results of the composition analysis of -2 to R-3 and the physical properties of the resin. [Table 4] [Table 5] Next, using the above resins R-2 to R-3,
The same operation as in Example 1 was performed to obtain toners T-2 to T-3. Table 6 shows the results of the offset resistance test and the blocking resistance test of the obtained toners T-2 to T-3. [Table 6] From Table 6, it can be seen that the toners T-2 to T-3 have good offset resistance and blocking resistance. Examples 4 to 5 Resins R-4 to R-5 were obtained in the same manner as in Example 1 except that the polymerization charge composition was changed as shown in Table 7. Resin R
Table 8 shows the results of the composition analysis of -4 to R-5 and the physical properties of the resin. [Table 7] [Table 8] Next, using the above resins R-4 to R-5,
The same operation as in Example 1 was performed to obtain toners T-4 to T-5. Table 9 shows the results of the offset resistance test and the blocking resistance test of the obtained toners T-4 to T-5. [Table 9] Table 9 shows that the toners T-4 to T-5 have good offset resistance and blocking resistance. Comparative Examples 1 to 3 Example 1 was repeated except that the polymerization charge composition was as shown in Table 10.
By performing the same operation as described above, resins R-6 and R-8 were obtained. Table 1 shows the results of the composition analysis of the resins R6 and R-8 and the physical properties of the resins.
It is shown in FIG. When the polypropylene E of Comparative Example 2 was added in an amount of 70% by weight based on the total polyester, the reaction system was separated into two layers, and the polymerization did not proceed properly. [Table 10] [Table 11] Next, the same operation as in Example 1 was carried out using the above-mentioned resins R-6 and R-8 to obtain toners T-6 and T-8.
-8 was obtained. Table 12 shows the blocking resistance test and offset resistance test results of the obtained toners T-6 and T-8.
Shown in In the toner T-6, since the amount of the aromatic dicarboxylic acid used in the acid component was small, the Tg was lowered, and the blocking resistance and the offset resistance were lowered. Further, the toner T-8
When the viscosity was reduced without using a polypropylene polymer, the fixing property was considerably improved, but a high-temperature offset occurred at 150 ° C. [Table 12] Comparative Examples 4 to 6 Example 1 was repeated except that the polymerization charge composition was as shown in Table 13.
By performing the same operation as above, resins R-9 to R-11 were obtained. Table 14 shows the analysis results and the resin physical properties of the resins R-9 to R-11.
Shown in [Table 13] [Table 14] Next, using the above resins R-9 to R-11,
The same operation as in Example 1 was performed, and toners T-9 to T-11
Got. Table 15 shows the test results of the blocking resistance and the offset resistance of the obtained toners T-9 to T-11. T-9 has a high Tg of 82 ° C. and thus has good offset resistance and blocking resistance, but has a fixing property of 167 ° C.
And dropped significantly. T-10 can be used at a C level because the silica was added at 5% by weight at the time of forming the toner, but when the softening temperature is lowered to 75 ° C.,
Even when the polypropylene polymer was subjected to block polymerization, almost no non-offset fixing temperature width was obtained. In addition, T-11
Is a resin having a high softening temperature of 179 ° C. and good blocking resistance, but poor fixability of 170 ° C. [Table 15] Comparative Example 7 Polymerization was carried out by repeating the same operation as in Example 1 except that the polymerization charge composition was as shown in Table 16, except that the molecular weight Mw was 60 and
000, the compatibility with the polyester resin was poor, and the polymerization system separated into two layers. [Table 16] As described above, the polyester resin for a toner of the present invention is obtained by polycondensing a polypropylene polymer containing an ester bond-forming group having a specific molecular weight, whereby low-temperature fixability, blocking resistance, and It has excellent offset resistance and is useful as a dry toner used for an electrostatic image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichi Nagai 4-1, Ushikawa-dori, Toyohashi-shi, Aichi Prefecture Inside Mitsubishi Rayon Co., Ltd. Toyohashi Office (56) References JP-A-3-50561 (JP, A) JP-A-3-881 (JP, A) JP-A-4-95968 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/087

Claims (1)

(57) Claims: (a) a dicarboxylic acid component containing at least one aromatic dicarboxylic acid or a lower alkyl ester thereof, (b) a trivalent or higher polyvalent carboxylic acid and / or (D) at least one polyhydric alcohol or lower ester thereof, (c) a diol component containing at least one aromatic diol represented by the following general formula (I), and (d):
A polypropylene polymer containing an ester bond-forming group having a weight average molecular weight Mw of 50,000 or less;
The component is 60 mol% or more based on the total acid component in the polyester, and the component (d) is 50% based on the total condensed polyester.
A polymer having a glass transition point Tg
And a softening temperature of 85 to 170 ° C. Embedded image