JP3090752B2 - Polyester resin for recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin useful as a dry toner for developing an electrostatic image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like. More specifically, the present invention relates to a polyester which is excellent in melt fluidity and fixability, and is particularly useful for full color applications requiring high melt fluidity, and for high-speed copying machines and high-speed printers requiring low-temperature fixability.

[0002]

2. Description of the Related Art In a method for obtaining a permanent visible image from an electrostatic image, an electrostatic image formed on a photoconductive photoreceptor or an electrostatic recording medium is developed with a toner previously charged by friction. Be established. 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 involves directly fusing the toner image obtained by development on the photoconductive photoreceptor or electrostatic recording medium, or transferring the toner image onto paper or film and then fusing it on a transfer sheet. Done by The fusing of the toner image is performed by contact with solvent vapor, pressurization and heating, and there are two types of heating methods: a non-contact heating method using an electric oven and a pressure heating method using a pressure roller. The latter, which requires higher speed, is used.

In order to further obtain a color image, toners of three or four colors must be adhered to transfer paper in the above-described development step, and then, in a fixing step, various toners must be melted and mixed to form a color and fixed. As described above, there is a strong demand for a binder for a full-color toner which has a good mixing property in the fixing step, in other words, a resin having a good melt fluidity. When a binder having good melt fluidity is used, there is a problem that an offset phenomenon occurs in a fixing process. However, when the binder is cross-linked or polymerized to prevent the offset phenomenon, the melt fluidity is reduced, and the binder is not suitable for full-color copying. Therefore, a method of applying silicone to the surface of a fixing roller of a copying machine to prevent offset has been used.

In recent years, there has been a strong demand for high-speed and energy-saving fixing units, and in copiers and printers other than full-color copiers, a method of applying silicone to a fixing roller as an offset prevention measure is often used. . Hitherto, as a resin for a toner, a low-molecular polyester comprising a divalent carboxylic acid and an aromatic diol that provides a rigid polymer has been proposed in order to impart blocking resistance to melt fluidity. However, since the aromatic diol component has poor reactivity, a reaction at a high temperature is necessary to obtain desired physical properties,
As a result, the aromatic diol is decomposed, giving off a bad smell. Problems such as deterioration of image quality occur. In addition, aromatic diols have poor reactivity, so their molecular weight is limited, and a large amount of excessively pulverized products are generated in the toner production process.

[0005] In order to further increase the reactivity with aromatic diols, examples of using unsaturated dicarboxylic acids have been introduced. However, the effect is small and hydroquinone used as a radical reaction inhibitor causes pollution problems. There is a concern that this will occur. From the above situation, as a low-molecular weight toner binder resin of full color and fixability,
Good melt fluidity and thermal stability and polymerization reactivity,
There is also a strong demand for a resin having excellent pulverization characteristics.

[0006]

It is an object of the present inventors to provide a resin having good fixing properties and excellent blocking resistance in the prior art. More specifically, an object of the present invention is to provide a resin having a low molecular weight and a high Tg by introducing a naphthalene skeleton into a conventional low molecular weight polyester resin.

That is, by using naphthalenedicarboxylic acid as an acid component, a polymer can be sufficiently rigid even with a low molecular weight, so that a higher Tg can be achieved with a lower viscosity than that of a conventional polyester. Further, since the naphthalene-based monomer has better reactivity than general terephthalic acid, an increase in the concentration of an aromatic diol having poor reactivity can be achieved, and a lower molecular weight and a higher Tg can be achieved.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve these problems, and as a result, have found a polyester resin having good melt fluidity and fixability and good blocking resistance. The present invention has been completed. The present invention relates to a polyester obtained by condensing 3 mol% or more of a naphthalenedicarboxylic acid or a lower alkyl ester component thereof with 10 mol% or more of an aromatic diol component represented by the formula (1) based on all acid components, softening temperature T _1/2 of the polyester resin is a eighty-five to one hundred and sixty ° C., a glass transition temperature T
g is 40-90 ° C. and molecular weight Mw is 3000-4
0000, which relates to a recording material polyester resin.

The lower alkyl ester of naphthalenedicarboxylic acid referred to in the present invention includes dimethyl naphthalate, diethyl naphthalate, dibutyl naphthalate, etc.
Dimethylnaphthalate is preferred in terms of cost and handling. The naphthalene component raises Tg and contributes to blocking resistance, and also has an effect on moisture resistance due to its hydrophobicity. Further, the naphthalene-based monomer has an effect of increasing the Tg of the resin, and has an effect of imparting cohesiveness to the resin and increasing the offset resistance. Although the naphthalene component has an effect commensurate with the amount used, the effect is remarkably exhibited at 3 mol% or more, preferably 5 mol%, based on the total acid component.
It is necessary to use more than mol%. As for other acid components, terephthalic acid component, isophthalic acid component, unsaturated dicarboxylic acid component and the like can be used. Among them, terephthalic acid has an effect of increasing Tg, and isophthalic acid has an effect of increasing reactivity. The use balance may be changed depending on the purpose.

Aromatic diol component (1) in the present invention
In the past, the amount used was limited because of poor reactivity. However, when highly reactive naphthalene was used as the acid component, a large amount of the aromatic diol component (1) could be used, resulting in low viscosity and high Tg. The effect of the present invention is further achieved.
Examples of the aromatic diol (1) in the present invention 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 the aromatic diol (1) has an effect of increasing Tg, the blocking resistance is improved.

When the amount of the aromatic diol (1) used is 10 mol% or less based on the total acid components, the desired T
To obtain g, a considerable molecular weight and viscosity are required, and the melt fluidity is reduced. Therefore, the amount of the aromatic diol (1) used is preferably at least 10 mol%, more preferably at least 20 mol%, based on the total acid components. The most important point regarding the present invention is that the softening temperature T of the polymerized polyester is
_1/2 is 85 to 160 ° C., Tg is 40 to 90 ° C., and molecular weight Mw is 3,000 to 40,000.

When the softening temperature T _1/2 is less than 85 ° C., the melt fluidity is improved, but the cohesiveness of the resin is extremely reduced, and an offset to the roller occurs during copying. On the other hand, if the softening temperature T _1/2 exceeds 160 ° C., on the contrary, the melt fluidity and the fixability are lowered, and a toner using the resin is not suitable for a full-color or high-speed printer or a high-speed printer with a fixation standard. Therefore, the softening temperature T1 _{/ 2} needs to be 85 to 160C, preferably 90 to 155C.

In general, the addition of an inorganic powder such as silica to the toner is effective in improving the blocking resistance, and the effect is particularly remarkable when the binder has a low Tg. or,
When the Tg is 50 ° C. or higher, the blocking resistance is good even without adding an inorganic powder. Therefore, Tg needs to be 40 ° C. or higher, preferably 50 ° C. or higher. On the other hand, when the Tg exceeds 90 ° C., the melt fluidity is lowered, and it is not suitable for a full-color toner.

On the other hand, if the molecular weight Mw exceeds 40,000, the viscosity increases and the pulverizability deteriorates, so that a toner using the same is not suitable for a full-color toner requiring high melt fluidity. Therefore, the molecular weight Mw is 40,000 or less, preferably 35,000 or less. Also, Mw
Is less than 3000, the melt fluidity is good, but the Tg is extremely reduced, and the blocking property is deteriorated.

In the present invention, monomers other than the above-mentioned monomers can be used according to the required performance.
In general, monomers known as raw materials for polyesters include:
It may be used as long as the effects of the present invention are maintained.
For example, in the dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, sebacic acid, isodecyl succinic acid, maleic acid, fumaric acid, adipic acid, and monomethyl, monoethyl, dimethyl, diethyl ester thereof, and the like, in particular, terephthalic acid , Isophthalic acid, and dimethyl esters thereof are preferred in terms of blocking resistance and cost. These divalent carboxylic acids and lower esters thereof affect the fixability and blocking resistance of the toner. When an 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 cause a decrease in Tg, which leads to a decrease in blocking resistance. In the case of aliphatic acids, this tendency is stronger for longer-chain monomers.

As examples of the use of diols, aliphatic and aromatic diols are used. Examples of the aliphatic diol include ethylene glycol, neopentyl glycol, butanediol, polyethylene glycol, cyclohexane dimethanol, hydrogenated bisphenol A, and the like. Ethylene glycol, neopentyl glycol, and butanediol are preferable from the viewpoint of fixability. Also, for example, 1.4-bis (2-hydroxyethoxy) benzene,
1.4-bis (2-hydroxybutoxy) benzene,
Use of 1.4-dihydroxymethylbenzene or the like has an effect on moisture resistance.

In the present invention, the monomer is charged into a reaction vessel and heated to raise the temperature, whereby an esterification reaction or
Perform transesterification. At this time, an esterification catalyst or a transesterification catalyst such as sulfuric acid, titanium butoxide, dibutyltin oxide, magnesium acetate, and manganese acetate, which is used in a usual esterification reaction or transesterification reaction, can be used as necessary. Then, water or alcohol generated by the reaction is removed according to a conventional method.

In the present invention, a polymerization reaction is subsequently carried out. At this time, the polymerization is carried out while distilling and removing the diol component under a vacuum of 150 mmHg or less. In the polymerization, a generally known polymerization catalyst, for example, titanium butoxide,
Dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony oxide, germanium oxide, 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 present invention, the softening temperature is defined by a flow tester CFT-500 manufactured by Shimadzu Corporation under the condition of a 1.0 mmφ × 10 mm nozzle, a load of 30 kgf, and an isothermal heating at a heating rate of 3 ° C./min. When measured, sample 1.0
The temperature at which 1/2 of the gram flows out. The Tg in the present invention is the Tg measured at a temperature rise of 5 ° C./min with a Shimadzu DSC.
A contact point between the tangent of the nearby endothermic curve and the baseline was used.

The weight-average molecular weight M _W is G
It refers to M _W that is measured by the PC HCL-8200.
In the composition analysis in Examples in the present invention, the resin was hydrolyzed with hydrazine and quantified by liquid chromatography. Next, the present invention will be described by way of examples, but embodiments of the present invention are not limited thereto. Unless otherwise indicated, the amounts of components in the examples represent parts by mole.

[0021]

【Example】

Example 1 According to Table 1, naphthalenedicarboxylic acid, terephthalic acid, ethylene glycol, and polyoxypropylene (2.3) -2,2-bis (4-hydroxyphenyl) propane were charged into a reaction vessel having a distillation column. . The catalyst, dibutyltin oxide, was added in an amount of 0.1 to the total acid components.
08 parts by weight, an internal temperature of 260 ° C., and a stirring rotation speed of 200.
After the esterification reaction was carried out under normal pressure for 5 hours while maintaining the rpm, the pressure in the reaction system was reduced to 1.0 mmHg over 30 minutes, the internal temperature was maintained at 260 ° C, and the condensation reaction was carried out for 2 hours while distilling ethylene glycol. Then, white resin R-1 was obtained.
Table 2 shows the results of the composition analysis and the physical properties of the obtained resin.

[0022]

[Table 1]

[0023]

[Table 2]

The unit is molar part. * Diol A: polyoxypropylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane 95% by weight of the obtained resin was premixed with 5% by weight of carbon black (Mitsubishi Kasei # 40) using a Henschel mixer, and then using an internal mixer manufactured by Kurimoto Tekko. Melt kneading was performed at 140 ° C. and 65 rpm. After cooling the melt-kneaded product to room temperature, it was roughly pulverized by a hammer mill, and then pulverized to 22 μm or less using a jet mill. Then, using a pneumatic classifier of Nippon Pneumatic Co., Ltd., the particle size was adjusted to 5 to 22 μm to obtain toner T-1. Table 3 shows the offset resistance test result, the fixing test result, and the blocking resistance test result of Toner T-1.

[0025]

[Table 3]

The offset resistance was determined by uniformly sprinkling the toner on paper (ID = 1.0 ± 0.3), passing the toner through a temperature-variable fixing roller, and setting the speed of the offset fixing roller to 100 mm / sec. The nip width was set to 8.0 mm for evaluation. As the temperature of the roller was increased, it was visually observed whether the toner adhered to the roller. The temperature at which the toner began to adhere to the roller was defined as the temperature at which the high-temperature offset was started. A resin that did not generate an offset at 130 ° C. or lower under the above conditions was determined to have good offset resistance in full-color and high-speed machines. However, the offset referred to here means a high-temperature offset, and does not include a cold offset generated when the fixing property is insufficient.

The fixing rate was set at a roller speed of 100 mm /
In sec, the nip width was 8.0 mm and the fixing rate was 120 ° C. Spread toner evenly on paper (ID = 1.
0 ± 0.3), the density decay rate when the tape is peeled off after passing through the fixing roller. The fixation rate is taken as a numerical value corresponding to the melt fluidity of full color or the like.
A resin having a fixing rate of 0% or more was defined as a resin having good melt fluidity.

To evaluate the blocking resistance, 5 g of the toner was placed in a 50 ml glass sample bottle, left in a high-temperature bath at 50 ° C. for 50 hours, and then observed for the degree of aggregation. The degree of aggregation was set as follows. The sample bottle left at 50 ° C. for 50 hours is cooled to room temperature, and the degree of aggregation is observed and evaluated.

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. (It was determined that the cohesion degrees A, B, and C could be used.)

From Table 3, it can be seen that the toner T-1 has good melt fluidity and blocking resistance, and also has good offset resistance.

[Examples 2 to 4] Table 4 shows the charged monomer composition.
Except for the following, the same operation as in Example 1 was performed to obtain resins R-2 to R-4. Next, Table 5 shows the results of the composition analysis and the resin physical properties of the resins R-2 to R-4. In addition, the end point of the reaction was sampled from the polymerization kettle and the softening temperature was measured.
The end point was reached when any softening temperature was reached.

[0032]

[Table 4]

Unit: molar part * Diol A: polyoxypropylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane * diol B: polyoxyethylene (2.3) -2,2
-Bis (4-hydroxyphenyl) propane

[0034]

[Table 5]

Unit: molar part * Diol A: polyoxypropylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane ** diol B: polyoxyethylene (2.3) -2,
2-Bis (4-hydroxyphenyl) propane Further, the same operation as in Example 1 was performed, and the resins R-2 to R-
Thus, toners T-2 to T-4 corresponding to No. 4 were obtained. T-2 to T
Table 6 shows the results of the fixing property, offset resistance test and blocking resistance test of No. -4.

[0036]

[Table 6]

From Table 6, it can be seen that the toners T-2 to T-4 have good melt fluidity and anti-offset properties and good blocking resistance.

[Examples 5 and 6] Table 7 shows the monomer charge composition.
Except for the following, the same operation as in Example 1 was performed to obtain resins R-5 to R-6. Table 8 shows the results of the composition analysis and the resin physical properties of the resins R-5 to R-6. Incidentally, the end point of the reaction was determined by sampling from the polymerization vessel and measuring the softening temperature, and when the softening temperature was reached, the end point.

[0039]

[Table 7]

Unit: molar part * Diol A: polyoxypropylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane

[0041]

[Table 8]

Unit: molar part * diol A: polyoxypropylene (2.3) -2,
2-Bis (4-hydroxyphenyl) propane Further, the same operation as in Example 1 was performed, and the resins R-5 to R-
Thus, toners T-5 to T-6 corresponding to No. 6 were obtained. T-2 to T
Table 9 shows the results of the fixing property, offset test and blocking resistance test of No. -4.

[0043]

[Table 9]

Table 9 shows that the toners T-5 to T-6 have good melt fluidity and anti-offset properties and good blocking resistance.

[Comparative Examples 7 to 12] Resins R-7 to R-12 were obtained in the same manner as in Example 1, except that the monomer charge composition was changed as shown in Table 10. Resins R-7 to R-1
Table 11 shows the composition analysis result and resin physical properties of Sample No. 2. still,
The end point of the reaction was determined by sampling from the polymerization vessel and measuring the softening temperature, and when the temperature reached an arbitrary softening temperature, was taken as the end point.

[0046]

[Table 10]

Unit: molar part * Diol A: polyoxypropylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane ** diol B: polyoxyethylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane

[0048]

[Table 11]

Unit: molar part * Diol A: polyoxypropylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane ** diol B: polyoxyethylene (2.3) -2,
2-bis (4-hydroxyphenyl) propane

[0050]

[Table 12]

The same operation as in Example 1 was performed to obtain corresponding toners T-7 to T-12. Table 12 shows the evaluation results of the respective toners. However, T-7, T-8,
As for T-10 and T-12, 5 wt% of Aerosil R-972 was added to the produced toner at the time of kneading in the toner forming step in order to impart blocking resistance. According to Table 12, T-7 is an example in which naphthalenedicarboxylic acid was not used, but the cohesiveness of the resin was lower than that in the case where naphthalene was used, and offset occurred at 120 ° C. When the softening temperature was set to 85 ° C. at T-8, the fixing strength was improved, but offset occurred in the entire temperature range. T-9 has a softening temperature of 1
Although it is a case where it is set to 65 ° C., Tg is as high as 83 ° C.,
Although the blocking resistance is good, it is suitable for general low-speed copying machines because the melt fluidity is reduced, but it is suitable for full-color or high-speed machines and high-speed printers because the melt fluidity is reduced. Not suitable.

When the Tg is 27 ° C., even if a naphthalenedicarboxylic acid is used, the blocking resistance is not good (T-10). T-11 uses a polyfunctional monomer and has a higher molecular weight, but the offset resistance is considerably improved, but the melt fluidity is lowered, so it is not suitable for full-color or high-speed copying machines . T-12 was a case where a predetermined amount of aromatic diol was not used, but Tg did not increase even when the softening temperature referred to in the present invention was reached, and no offset resistance was obtained.

────────────────────────────────────────────────── ─── 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-64-15755 (JP, A) Kaihei 3-229265 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/087

Claims (1)

(57) [Claims] 1. A polyester obtained by condensing 3 mol% or more of a naphthalenedicarboxylic acid or a lower alkyl ester component thereof with 10 mol% or more of an aromatic diol component represented by the formula (1) based on all acid components. The softening temperature T _{1/2 of the} polyester resin is 85 ° C. or more and 160 ° C. or less, the glass transition point Tg is 40 to 90 ° C., and the average molecular weight Mw
Is 3000 to 40,000. Embedded image