JP3442117B2 - 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, polyester for toner which is excellent in blocking resistance, melt fluidity and low-temperature fixability, is particularly useful for full color applications requiring high melt fluidity, high-speed copying machines and high-speed printers requiring low-temperature fixability. About resin. 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:
The fusion 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.
Recently, the latter is mainly used, which requires a high-speed fixing process. [0003] Toner used in the dry development system includes 1
There are two-component toners and two-component toners. 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 ground, then finely ground 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, resins for toners are required to have good dispersibility of the colorant in the melt-kneading step and good pulverizability in the pulverization step in the production of toner. Various performances such as 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. For the pressure fixing method, a copolymer of styrene and (meth) acrylate is mainly used. Has 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. [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. . On the other hand, in order to obtain a color image, toners of three to four colors must be adhered to transfer paper in the above-described development step, and then, in a fixing step, the color is developed and fixed while various kinds of melting and mixing are performed. . For this reason, as the binder resin for a full-color toner, a resin having good mixing properties in the fixing step as described above, in other words, a resin having good melt fluidity is strongly desired. However, when a binder resin having good melt fluidity is used, there is a problem that an anti-offset phenomenon occurs in a fixing step. When the binder resin is cross-linked or polymerized to prevent the offset resistance phenomenon, the melt fluidity is reduced, and thus the binder resin is not suitable as a binder resin for a full-color toner. Also,
Even if PP wax is added as an anti-offset agent,
As described above, the polyester resin has poor compatibility with the PP wax, and is not particularly suitable for a full-color toner because the color of a toner image is deteriorated. Therefore, in the case of a full-color copying machine, silicone oil or the like is applied to the surface of the fixing roller in order to obtain offset resistance. However, if silicone oil or the like is applied to the fixing roller, the oil may adhere to the copy, which may hinder handling. In particular, this phenomenon is remarkable when copying is performed on an OHP or the like. For this reason, there is a strong demand for a binder resin for a full-color toner capable of offset resistance with a single toner without applying silicone oil or the like to the fixing roller. SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester resin for toner which is excellent in blocking resistance, melt fluidity and low-temperature fixability and has good offset resistance. Means for Solving the Problems The present inventors have studied to achieve the above object, and as a result, have found that a polyester resin containing a specific polypropylene polymer as a polymer component can achieve the object. The present invention has been completed. That is, the present invention comprises (a) a dicarboxylic acid component containing at least one aromatic dicarboxylic acid or a lower alkyl ester thereof, and (b) at least one aromatic diol represented by the following general formula (I). A diol component, and (c) a polypropylene polymer having an ester bond-forming group having a weight average molecular weight Mw of 50,000 or less, wherein the component (a) is 60% of the total acid component in the polyester.
A polymer in which the component (c) is 50% by weight or less based on the total condensed polyester, and has a glass transition point Tg (hereinafter abbreviated as Tg) of 40 to 70 ° C.
And a polyester resin for toner having a softening temperature of 85 to 120 ° C. [0010] The aromatic dicarboxylic acid or its lower alkyl ester (a) used in the present invention comprises an aromatic dicarboxylic acid such as terephthalic acid or 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 aromatic diol (b) 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 and 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)-
Examples thereof include 2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane. These may be used alone or in combination of two or more. Used. Since the aromatic diol (b) has an effect of increasing the Tg of the resin, the blocking resistance is improved. The amount of the aromatic diol component (b) used is preferably 80 mol% or less 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. Further, in the present invention, in order to impart offset resistance to a conventional toner resin comprising a polyester resin, a polypropylene polymer (c) containing an ester bond-forming group is prepared by adding a dicarboxylic acid component (a) and a diol. It is polycondensed with the component (b). The amount of the polypropylene polymer (c) used is:
It is 50% by weight or less, preferably 3 to 40% by weight, based on the total condensed polyester, and its weight average molecular weight Mw is 50,000 or less, preferably 200 to 4%.
It is in the range of 0000. This is because when the amount of the polypropylene polymer (c) used 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 reduced. As a result, the dispersibility as a toner is inferior, the charging stability is reduced, and the color of the toner image is deteriorated. The amount of the polypropylene polymer (c) used is less than 3% by weight or its weight average molecular weight M
If w is less than 200, the offset resistance tends not to be sufficiently imparted. Further, the polypropylene polymer (c) used in the present invention needs to have an ester bond-forming group for reacting with the carboxylic acid component (a) and the diol component (b). The ester bond forming group in the polypropylene polymer (c) is not particularly limited, but it is preferable to use one obtained by modifying one or both terminals of the polypropylene polymer with an acid, for example, maleic acid. 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 for polyester may be used as long as the effects of the present invention are maintained. For example, as a dicarboxylic acid component, aliphatic dicarboxylic acids such as sebacic acid, isodecyl succinic acid, fumaric acid, adipic acid, and monomethyl, monoethyl, dimethyl, diethyl ester and the like thereof are contained in an amount of 30 mol% based on the total acid component. Available in range. 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 the softening temperature must be 85-120 ° C. This is because when Tg is less than 40 ° C., the fixing property is improved, but the blocking resistance is significantly reduced.
If the Tg exceeds 75 ° C., the blocking resistance is improved, but the fixability is lowered. Further, when the softening temperature of the polyester resin is less than 85 ° C, the cohesive force of the resin itself is extremely reduced because the cohesiveness of the polymer itself is extremely reduced, and even if the polypropylene polymer is block-copolymerized,
Offset resistance deteriorates. On the other hand, the softening temperature is 120 ° C
If the ratio exceeds 0.5, 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 (c) are charged into a reaction vessel, and the temperature is elevated 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.) The tangent of the endothermic curve near Tg when measured at a temperature rise of 5 ° C./min using a differential scanning calorimeter manufactured by Shimadzu Corporation and the baseline. The contact was Tg. (2) Softening temperature (° C.) Using a flow tester (CFT-500) manufactured by Shimadzu Corporation, nozzle 1.0 mmφ × 10 mmL, load 30 k
g, the temperature was raised at 3 ° C./min, and the sample amount was 1.0 g. The temperature at which half of the sample flowed out was taken as the 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 fixed portion is tapered, and the density decay rate is determined.
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. Fixing property is 130 ° C or less, and offset resistance is 15
It was determined that 0 ° C. or higher was necessary for the full-color toner resin. (7) Blocking resistance 5 g of the 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. Abbreviations used in 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, diol A and diol B in the amounts shown in Table 1
And ethylene glycol were charged into a reaction vessel equipped with a distillation column. In addition, 10 to the calculated synthetic polymer amount
% By weight of a polypropylene polymer C having a reactive group capable of forming an ester bond (polypropylene having a molecular weight of 10,000 and both ends modified with maleic acid) and dibutyltin oxide as a catalyst in an amount of 0.03% by weight based on the total acid components. 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. Thereafter, the pressure in the reaction system was reduced to 1.0 mmHg over 30 minutes, the internal temperature was maintained at 260 ° C., and a condensation reaction was carried out for 4 hours while distilling ethylene glycol to obtain a pale yellow transparent resin R.
-1 was obtained. The obtained resin R-1 has a softening temperature of 1
The temperature was 12 ° C and the Tg was 59.8 ° C. Table 2 shows the results of the composition analysis and the physical properties of the obtained resin. [Table 1] [Table 2] Next, based on 94% by weight of the obtained resin R-1, carbon black (manufactured by Mitsubishi Kasei Corporation, # 40)
5% by weight, a charge control agent (manufactured by Orient Chemical Co., Ltd.
After 1% by weight of Bontron S-34) was premixed with a Henschel mixer, melt kneading was performed at 150 ° 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 coarsely pulverized by a hammer mill, and then cooled by a jet mill.
It was pulverized to not more than μm. Then, using a pneumatic classifier manufactured by Nippon Pneumatic Co., Ltd., the toner T having a particle size of 5 to 20 μm is used.
-1 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
Since the offset resistance and the blocking resistance are good, even when the resin R-1 is used as a full color,
It is determined that the fixing property is good and the offset resistance is also 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] Table 6 shows 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, and toners T-4 to T-5 were used.
I got 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 above, resins R-6 to R-8 were obtained. Table 11 shows the results of the composition analysis and the values of the physical properties of the resins R-6 to R-8.
Shown in [Table 10] [Table 11] Next, using the above resins R-6 and R-8,
The same operation as in Example 1 was performed, and toners T-6 and T-8
I got Table 12 shows the blocking resistance test and offset resistance test results of the obtained toners T-6 and T-8. 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. Toner T-
In No. 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. When the viscosity of toner T-8 was reduced without using a polypropylene polymer, the fixing property was considerably improved, but the non-offset fixing temperature range was hardly obtained. [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 T-9 to T-11,
The same operation as in Example 1 was performed, and toners T-9 to T-1 were used.
1 was obtained. 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 81 ° C. and thus has good offset resistance and blocking resistance, but has a fixing property of 135.
° C, which is unsuitable for a full color which requires melt mixing. 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 135 ° C. and good blocking resistance, but poor fixability of 145 ° 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
In the case of using a polymer having a molecular weight of 000, the compatibility with the polyester was poor, and the polymerization system was separated into two layers. [Table 16] As described above, the polyester resin for a toner of the present invention is obtained by condensation polymerization of a polypropylene polymer having an ester bond forming group having a specific molecular weight in a polymer, whereby blocking resistance and melt flow resistance are improved. , Low temperature fixability and offset resistance are good, for full color,
It is useful as a toner resin for high-speed copying machines and high-speed printers.

────────────────────────────────────────────────── ─── 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-2-881 (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, and (b) an aromatic compound represented by the following general formula (I). A diol component containing at least one aromatic diol, and (c) a polypropylene polymer containing an ester bond-forming group having a weight average molecular weight Mw of 50,000 or less, wherein the component (a) is based on all acid components in the polyester. A polymer comprising at least 60 mol% and the above component (c) at 50% by weight or less based on the total condensed polyester, having a glass transition point Tg of 40 to 70 ° C and a softening temperature of 85 to 120 ° C. A polyester resin for a toner, characterized by the following. Embedded image