JP3269864B2 - Polyester resin for toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin useful as a binder resin for a dry 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 provides a toner which has excellent printing durability and maintains a high image even when used for a long period of time by imparting strength to a binder. The present invention relates to a polyester resin for a toner which is effective for a magnetic one-component developing system and a portable developing system which has been rapidly spreading recently.

[0002]

2. Description of the Related Art In a method for obtaining a permanent visual image from an electrostatic image, an electrostatic image formed on a photoconductive photoreceptor or an electrostatic recording medium is developed by a toner charged in advance by friction. Established later. 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 there are two types of heating methods: non-contact heating method using an electric oven and pressure heating method 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 manufactured by first melting and kneading a resin, a colorant, a charge control agent and other necessary additives to sufficiently disperse the mixture, and then coarsely and finely pulverizing them and classifying them into a predetermined particle size range. Is done.
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 a major component in the formulation of the toner and governs most of the performance required of the toner. For this reason, toner resins are 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. Versatile performance such as good electrical properties and electrical properties is required. As the resin used for the production of the toner, epoxy resin, polyester resin, polystyrene resin, methacrylic resin and the like are known,
Copolymers of styrene and (meth) acrylate have been mainly used for the pressure fixing method.

However, as the performance of the copying machine has been improved, the performance requirements of the toner resin have also changed depending on the type of the copying machine. Among them,
In particular, small copiers (portable types), which have begun to spread remarkably recently, are often used in homes and the like, and therefore have a relatively low printing rate, and the toner is charged in the developing process in the copier. Therefore, the mixing time becomes long. During that time, the toner is pulverized, the particle size becomes smaller, the charge amount changes, and the density of the copy changes. In addition, when used for home use, maintenance is troublesome. Further, there is a developing system in which a toner is strongly pressed against a developing roll like a non-magnetic one component to charge the toner. In such a developing system, the toner because is easily crushed, you change the charge amount.

When a conventional styrene-based resin is used for the above-mentioned applications, the toner is easily pulverized due to insufficient strength of the resin, causing fog on a copy and a decrease in density. Is happening. To improve it,
Although a method of superpolymerization or an increase in Tg is employed, such a method greatly increases the viscosity and lowers the fixability.

Although a polyester resin which is considered to be strong is also used for a toner, it has a high cross-linking agent concentration due to emphasis on fixing properties, and its strength is reduced due to a small Mn. . Therefore, the fixability while maintaining some degree, yet is strong in the resin, such as the upper Symbol System
There is a keen need for a toner resin that can be used for a toner.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner resin useful for a developing system requiring the toughness described above. In particular, an object of the present invention is to provide a resin having a viscosity that can be used as a toner and having a toughness.

[0009]

According to the present invention, there is provided a crosslinked polyester polymerized from a dicarboxylic acid component, a diol component, a polyvalent carboxylic acid component or a polyhydric alcohol component. The amount of the acid or polyhydric alcohol used is 5 mol% or more and 20 mol% or less for a trifunctional monomer, and 1 mol% or more and 15 mol% or less for a monomer having four or more functional groups, based on all acid components. Yes, the toughness index of the polyester is 250μ
m to 600 μm, a glass transition point Tg of 65 ° C. or more and 85 ° C. or less, and a number average molecular weight Mn of the resin of 5200.
Der is, the lowest fixing temperature is 160 ° C. or less than 30,000 or more
To provide a toner for polyester resin, wherein the lower der Rukoto.

In the present invention, the dicarboxylic acid component is
It is a known dicarboxylic acid used for the polymerization of general polyesters, and includes aromatic dicarboxylic acids and aliphatic dicarboxylic acids. Among them, aromatic dicarboxylic acids introduced from terephthalic acid, isophthalic acid and their lower alkyl esters are composed of benzene rings having a strong hydrophobicity, and are therefore useful for obtaining moisture resistance of the toner. Examples of such lower alkyl esters include dimethyl terephthalic acid, dimethyl isophthalic acid, diethyl terephthalic acid, diethyl isophthalic acid, dibutyl terephthalic acid, and dibutyl isophthalic acid, but dimethyl terephthalic acid and dimethyl isophthalic acid are preferred in terms of cost and handling. Is preferred. The aromatic component increases the Tg of the obtained resin, contributes to blocking resistance, and has an effect on moisture resistance due to its hydrophobicity. Among them, those of terephthalic acid are effective to increase the Tg, since those of isophthalic acid is effect that Ru enhance reactivity may be changed the use balance the purpose.

In the present invention, a trivalent or higher polyvalent carboxylic acid component and a polyhydric alcohol component are used in order to provide a crosslinked structure. Refers to the components introduced. Examples of polycarboxylic acids include trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid,
2,5,7-naphthalenetricarboxylic acid, 1,2,4-
There are naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,2,7,8-octanetetracarboxylic acid and anhydrides thereof. Examples of polyhydric alcohols include sorbitol, 1,2,3,6-hexanetetralol, 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. Used alone or in a mixture. Such polyfunctional monomers, which has an effect of increasing the T g of the resin, the cohesion is imparted to the resin, since an effect of increasing the offset resistance, fixing temperature of the degree of crosslinking using a copying machine and copying speed It can be set freely according to.

The diol component in the present invention is a known diol component generally used in the condensation of polyester, and includes a component composed of an aromatic diol and an aliphatic diol. 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) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene (3.3) -2,2-
Bis (4-hydroxyphenyl) propane and the like are used, and these are used alone or in combination. Since aromatic diol has an effect of increasing the Tg, blocking resistance of the resulting resin is that Do good. Examples of the aliphatic diol include generally known monomers such as ethylene glycol, neopentyl glycol, and 1,4-butanediol. Aliphatic diol imparts flexibility to the tree fat, contributes to fixability, T g decreases, because an adverse effect on the blocking resistance, use these usage models
It can be set freely according to .

[0013] The most important point in the present invention is to toughness in polymerized polyester has been granted,
The amount of the polyfunctional monomer used in this case with respect to the total acid components, it is necessary that 20 mol% or less. When a polyfunctional monomer is used at a high concentration, the reaction of the three-dimensional structural portion is prioritized, and it becomes difficult to impart sufficient strength to the polymer. More specifically, the polymer reaches its gel point and begins to form a stitch structure before the main chain of the polymer grows sufficiently, so that the melt viscosity of the polymer itself increases, but the strength of the resin decreases. Although there are some differences according to use monomer species, using polyfunctional monomer, the total acid components is 20 mol% or less 5 mole% or more when a trifunctional monomer, the case of monomers having more than 4 functional 1
It is required to be 15 mol%.

In the present invention, the toughness of the resin is evaluated as follows. (1) General crushed resin is sieved, and the particle size is 1400 to 20
Prepare 50 g of a sample of 00 μm. (2) Finely pulverize 30 g of the pulverized product of (1) with a blender TR-BL manufactured by Trio Science (scale 10:30).
Seconds). (3) Assemble the sieve whose weight has been weighed in the order shown in FIG. (4) Weigh 20 g of the pulverized material obtained in the operation of (2). (5) Put it on the top of the sieve assembled in (3), and apply vibration for 30 minutes with a micro-type electromagnetic vibrating sieve M-2 manufactured by Tsutsui Rikakiki (scale: 10). (6) Weigh the weight of the resin on each sieve. (7) Each value is plotted on a semilogarithmic graph (as the cumulative weight of each mesh pass), and from the graph, the particle size passing 50 wt% of the whole is read.

In the above evaluation method, when a toner having a particle size smaller than 250 μm is used, the toughness of the toner is weak, the toner is crushed during development in a copying machine, and the charge amount of the toner is changed. It will affect the concentration. Further, when a toner using a resin having a particle diameter larger than 600 μm is used, the strength of the resin is good, and pulverization in a copying machine and generation of spent toner can be suppressed. However, since the strength of the toner is high, it is important as a toner. The fixability, which is an important factor, is reduced. Therefore, in the above-mentioned evaluation method, the pulverized particle size needs to be 250 to 600 μm, and preferably 300 to 550 μm.

When an inorganic powder such as silica is given to the toner, it is effective in improving the blocking resistance. The effect is particularly remarkable when the Tg of the binder is low. In a development system requiring toughness, when a resin having a Tg lower than 65 ° C. is used,
The toner fuses in the developing process, and the image deteriorates. Also,
When a resin having a Tg higher than 85 ° C. is used as the toner,
The toughness of the resin is improved, but the fixability is reduced. Therefore, Tg must be 65-85 ° C, preferably 68-80 ° C.

Also, factors affecting the toughness of the resin
-Is a number average molecular weight. Number average molecular weight is 520
When a resin smaller than 0 is used as the toner, the toughness is
The printing durability decreases. Conversely, the number average molecular weight
Exceeds 30,000, toughness can be obtained, but fixability
Decrease. In the production of the resin of the present invention, the esterification reaction or transesterification reaction is carried out by charging the monomer into a reactor and heating and raising the temperature. At this time, if necessary, 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 may be used. it can. Next, water or alcohol generated by the reaction is removed according to a conventional method.

In the present invention, the polymerization reaction is subsequently carried out. At this time, the polymerization is carried out under a vacuum of 150 mmHg or less while distilling and removing the diol component. In the polymerization, generally known polymerization catalysts such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, and germanium dioxide can be used. Further, the polymerization temperature and the amount of the catalyst are not particularly limited, and may be arbitrarily set as needed.

In the present invention, Tg refers to DSC manufactured by Shimadzu.
The contact between the tangent line of the endothermic curve near Tg and the baseline when measured at a temperature rise of 5 ° C./min. The softening temperature in the present invention refers to a flow tester manufactured by Shimadzu (GFT-50).
0), nozzle 1.0mmφ × 10mmL, load 30kgf
The temperature at which half of the sample (1.0 g) flowed out when measured at a temperature rise of 3 ° C./min. Also, the number average molecular weight (Mn) is determined by GPC manufactured by Tosoh Corporation.
It is a value measured using 700 form.

The term "crosslinked structure" as used in the present invention refers to a resin having a point at which the torque of the reaction system rapidly rises during polymerization, that is, a point beyond the so-called gel point. In the composition analysis in the examples of the present invention, the resin was hydrolyzed with hydrazine and quantified by liquid chromatography.

[0021]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Example 1 According to Table 1, 91 mol parts of terephthalic acid, 9 mol parts of trimellitic acid, polyoxypropylene (2.3) -2,2-
45 mol parts of bis (4-hydroxyphenyl) propane,
70 mol parts of ethylene glycol were charged into a reaction vessel having a distillation column. 0.08 parts by weight of dibutyltin oxide as a catalyst was added to all the acid components, and the internal temperature was 260 ° C.
After the esterification reaction was performed for 5 hours under normal pressure while maintaining the stirring rotation speed at 200 rpm, 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 kept at 240 ° C., and the condensation reaction was carried out for 2 hours while distilling off ethylene glycol to obtain a pale yellow transparent resin R-1. Tg of the obtained resin is 70 ° C.
And the toughness evaluation result was 475 μm. Table 2 shows the results of the composition analysis.

[0022]

[Table 1]

^* Diol A: polyoxypropylene (2.3) -2,2-bis (4-hydroxyphenyl)
propane

[0024]

[Table 2]

With respect to 94% by weight of the obtained resin, 5% by weight of carbon black (Mitsubishi Chemical # 40) and 1% by weight of Bontron S-34 (Orient Chemical Industries) are premixed with a Henschel mixer, and then manufactured by Kurimoto Tekko Melt kneading was performed at 170 ° C. and 65 rpm using an internal mixer. After cooling the melt-kneaded product to room temperature, it was coarsely pulverized by a hammer mill, and then 22 μm was jet-milled.
m or less. Then, using a pneumatic classifier manufactured by Nippon Pneumatic Co., Ltd., the particle size is reduced to 5 to 22 μm.
-1 was obtained. For the toner T-1, a fixing test and a printing durability test were performed using a non-magnetic one-component printer modified to a variable temperature type. Table 3 shows the test results.

[0026]

[Table 3]

Here, the fixing temperature is defined as the initial density ID = 1.0 ± 0.
The portion No. 3 was passed through a temperature-variable fixing roller, and the tape was then peeled off from the fixing portion to determine the density decay rate. When the temperature of the roller is raised, the fixing rate is 90%
Is the fixing temperature. Set the fixing roller speed to 100mm / sec and set the nip width to 8.0mm.
And evaluated. A resin having a minimum fixing temperature of 160 ° C. or less was defined as a resin having good fixability.

Further, a printing durability test was carried out with a copying machine of an actual non-magnetic one-component system, and the image change after copying 5,000 sheets was visually evaluated. The evaluation was evaluated as follows. A: A clear image was obtained from the beginning to the end. B: Image density slightly changed in the middle, but was judged to be good throughout.

C: A good image was obtained up to the endurance of 1000 sheets. D: Image quality deteriorated from the beginning of the printing durability test. Tables 2 and 3 show that when the resin R-1 was used as the toner, the resin had good fixing behavior and excellent printing durability. Examples 2 to 3 Example 1 was repeated except that the monomer charge composition was as shown in Table 4.
By performing the same operation as described above, resins R-2 and R-3 were obtained.
Table 5 shows the composition analysis results and the resin physical properties of the resins R-2 and R-3.

[0030]

[Table 4]

^* Diol A: polyoxypropylene (2.3) -2,2-bis (4-hydroxyphenyl)
propane

[0032]

[Table 5]

Further, the same operation as in Example 1 was performed, and the toners T-2 and T-
3 was obtained. Table 6 shows the results of the fixing test and the printing durability evaluation of the toners T-2 and T-3. From these results, the resin R
It was found that when -2 and R-3 were used as the toner resin, the fixability and the printing durability were good.

[0034]

[Table 6]

Examples 4-5 Example 1 was repeated except that the monomer charge composition was as shown in Table 7.
By performing the same operation as described above, resins R-4 and R-5 were obtained.
Table 8 shows the results of the composition analysis of the resins R-4 and R-5, the values of the physical properties of the resins, and the toner characteristics when the toner was made in accordance with Example 1.

[0036]

[Table 7]

[0037]

[Table 8]

From Table 8, it can be seen that when the resins R-4 and R-5 are used as the toner, the fixing properties and the printing durability are excellent. Comparative Examples 1 to 3 Example 1 except that the monomer charge composition was as shown in Table 9.
By performing the same operation as described above, Resins R-6 to R-10 were obtained. Table 10 shows the analysis results, resin physical property values, and examples of Resins R-6 to R-10.

[0039]

[Table 9]

[0040]

[Table 10]

The resin R-6 uses a large amount of a polyfunctional monomer, and therefore has a wide molecular weight distribution. When the resin R-6 is used as a toner, the resin R-6 has good thermal characteristics (fixing property), but has a good When the number average molecular weight was insufficient and the development was continued, the toner was pulverized in the developing machine, the charge amount increased, and the image density changed. Therefore, it is understood that a resin using a polyfunctional monomer at a high concentration is not suitable for a toner for a developing system requiring toughness.

When resin R-7 is used as a toner,
Due to the low Tg, fusing and blocking occurred in the toner box and the developing system during the printing test, and a good image was not obtained. When the resin R-8 was used as a toner, the Tg was high and the pulverization evaluation was good, so that a good result was obtained in the printing durability test, but the fixability was lowered.

The resin R-9 was produced on a trial basis with the number average molecular weight set to about 3000, but the Tg was drastically reduced. When this was used as a toner, the printing durability was extremely deteriorated. Conversely, the resin R-10 has a number average molecular weight of 30.
Although it was designed to be 000 or more, the Tg was high, the toughness index was high, and the printing durability was extremely good, but the fixability was lowered.

[0044]

As described above, according to the present invention, there is provided a toner resin useful for a developing system requiring toughness in the toner. In particular, there is provided a polyester resin which has a viscosity that can be used as a toner and also has a toughness and can be advantageously used as a resin for a toner.

[Brief description of the drawings]

FIG. 1 is a diagram showing an assembling order of a sieve whose mass was measured in evaluation of toughness of a resin, and a numerical value in the figure indicates a roughness of a sieve.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoichi Nagai 4-1, Ushikawa-dori, Toyohashi-shi, Aichi Prefecture Inside the Mitsubishi Rayon Co., Ltd. Toyohashi Plant (56) References JP-A-1-155361 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (1)

(57) [Claims] A crosslinked polyester polymerized from a dicarboxylic acid component, a diol component, a polycarboxylic acid component or a polyhydric alcohol component, wherein the amount of the polycarboxylic acid or polyhydric alcohol used is based on the total acid component. In the case of a trifunctional monomer, it is 5 mol% to 20 mol%, and in the case of a tetrafunctional monomer, it is 1 mol% to 15 mol%, and the toughness index of the polyester is 250 μm.
m to 600 μm, a glass transition point Tg of 65 ° C. or more and 85 ° C. or less, and a number average molecular weight Mn of the resin of 5200.
Der is, the lowest fixing temperature is 160 ° C. or less than 30,000 or more
Polyester resin for a toner, wherein the lower der Rukoto.