JP3471054B2 - Polyester resin for toner and method for producing the same - 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 used for developing an electrostatic image or a magnetic latent image in an electrophotographic method, an electrostatic recording method, an electrostatic printing method and the like, and a method for producing the same. More specifically, it has a relatively high glass transition temperature, is excellent in toughness and printing durability, and is also excellent in fixability. Particularly, it is effective for a non-magnetic one-component developing system The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art In a method for obtaining a permanent visible image from an electrostatic charge image, an electrostatic charge image formed on a photoconductive photosensitive member or an electrostatic recording material is developed with a toner charged by friction in advance. It will be established later. In the case of a magnetic latent image,
The latent image on the magnetic drum is fixed after being developed with toner containing a magnetic material. For fixing, the toner image obtained by development is directly fused on the photoconductive photoconductor or the electrostatic recording body, or the toner image is transferred onto paper or film and then fused onto the transfer sheet. Done by. The fusion of the toner image is performed by contact with solvent vapor, pressurization or heating. As the heating method, there are a non-contact heating method using an electric oven and a pressure heating method using a pressure roller, but recently, the latter method is used because of the demand for speeding up the fixing process.

Toners used in the dry developing system include one-component toners and two-component toners. A two-component toner is manufactured by first melt-kneading a resin, a colorant, a charge control agent and other necessary additives to sufficiently disperse them, and then coarsely pulverizing and finely pulverizing them to classify them into a predetermined particle size range. To be done. On the other hand, the one-component toner is manufactured in the same manner by adding magnetic powder in addition to the respective components of the above two-component toner.

In the toner, since the resin used is the main component of the toner formulation, most of the performance required for the toner is governed by the resin. For this reason, the toner resin is required to have dispersibility of the colorant in the melt-kneading step in toner production and good pulverizability in the pulverization step, and to fix, offset, and block the toner in use. , Various properties such as electrical properties are required. Generally, epoxy resin, polyester resin, polystyrene resin, acrylic resin, etc. are used as the resin used in the production of toner. In the pressure-bonding heat fixing system, a copolymer of styrene and (meth) acrylic acid ester is mainly used. Is used. However, since the low temperature fixing property of the toner is strongly required with the increase in the speed of the copying machine, it is possible to fix the toner at a low temperature, and the fixed toner image has excellent resistance to vinyl chloride plasticizer. From the point of
Polyester resins have been receiving attention.

[0005]

However, as the performance of the copying machine is improved, the performance required for the toner resin is also changing depending on the type of the copying machine. For example, a portable type small copying machine is often used for general household use, has a relatively low printing rate, and the toner is mixed for a long time during charging in the developing process in the copying machine. In addition, there is a problem in that the toner is excessively pulverized and the particle size is reduced, and accordingly, the charge amount is changed and the density of the copy is changed.

In such a copying machine for home use or a plain paper facsimile, a non-magnetic one-component developing system has been used for the purpose of machine downsizing and maintenance-free. A method of charging by strongly rubbing is used. In such a developing system, by rubbing the toner against the developing roll in the charging step, the toner is easily crushed and the charge amount is apt to change very easily, and the toner is melted by the frictional heat generated during rubbing. There are problems such as wearing and sticking to the roll.

When a styrenic resin is used as the toner resin in such a developing system, the toner is extremely easily crushed due to insufficient strength of the resin, causing fog on the copy or density. It causes a problem such as a decrease in. In order to solve these problems,
Techniques such as super-polymerizing the resin and raising the glass transition temperature have also been used, but the viscosity of the resin increases drastically and the fixing property decreases. Although a polyester resin having strength higher than that of a styrene-based resin is used as a toner resin, generally, the fixing property is often increased by using a crosslinking agent at a high concentration, and the number average molecular weight is also small. However, the developing system as described above does not have sufficient strength. Therefore, a toner resin suitable for a developing system using a non-magnetic one-component toner having a high toughness and a relatively high glass transition temperature while maintaining the fixing property to some extent is desired.

An object of the present invention is to provide a toner resin suitable for a non-magnetic one-component toner having a relatively high glass transition temperature, a high toughness and an excellent fixing property, and a method for producing the same. is there.

[0009]

That is, the first aspect of the present invention
The polyester resin for a toner according to the present invention comprises a dicarboxylic acid component containing terephthalic acid as a main component, a diol component containing an aromatic diol and an aliphatic diol, and 1 to 13 mol% of trifunctional or more based on all acid components. A polyester resin composed of a polycarboxylic acid having a toughness index of 25.
0 to 600 μm and glass transition temperature Tg of 65 to 8
It is characterized in that the temperature is 5 ° C. The method for producing a polyester resin for toner according to the second aspect of the present invention comprises a dicarboxylic acid component containing terephthalic acid as a main component,
A diol component containing an aromatic didiol and an aliphatic diol and 1 to 13 mol% of a trifunctional or higher polyvalent carboxylic acid based on the total acid component have a molar ratio of the diol component to the acid component of 1.3 or less. As described above, the esterification reaction or the transesterification reaction is performed at a temperature of 250 ° C. or higher, and then the polymerization reaction is performed.
It is characterized by producing a polyester resin having a μm and a glass transition temperature Tg of 65 to 85 ° C.

In the present invention, the dicarboxylic acid component constituting the polyester resin contains terephthalic acid as a main component from the viewpoint of improving the toughness and glass transition temperature of the polyester resin, and the content of terephthalic acid is preferable. Is 60 mol% or more based on all acid components,
More preferably, it is in the range of 70 mol% or more. As the raw material, terephthalic acid or a lower alkyl ester thereof can be used, and examples of the lower alkyl ester include dimethyl terephthalate, diethyl terephthalate, dibutyl terephthalate, etc., but dimethyl terephthalate from the viewpoint of productivity such as handling property. Is preferred.

As the dicarboxylic acid component other than terephthalic acid, the dicarboxylic acid usable in the present invention is
Examples thereof include isophthalic acid, phthalic acid, sebacic acid, isodecyl succinic acid, maleic acid, fumaric acid, adipic acid, their lower alkyl esters and acid anhydrides. Above all,
Isophthalic acid has the effect of increasing the reactivity and can be appropriately used for the purpose of increasing the reactivity during the production of the polyester resin. Further, the aliphatic dicarboxylic acid can be appropriately used for the purpose of improving the fixability and blocking resistance of the toner.

In the present invention, the diol component constituting the polyester resin contains an aromatic diol and an aliphatic diol, and the aromatic diol is 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, polyoxyethylene-
(2.3) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.3) -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 can be mentioned. These aromatic diols have the effect of increasing the toughnel and glass transition temperature of the polyester resin, and improve the printing durability and blocking resistance of the toner, but on the other hand, if contained in a large amount, the reactivity decreases and the high molecular weight No polyester resin can be obtained. Examples of the aliphatic diol include ethylene glycol, neopentyl glycol, 1,4-butanediol and the like. These aliphatic diols increase the reactivity and impart flexibility to the polyester resin to improve the fixing property of the toner, but on the other hand, when used in a large amount, the glass transition temperature lowers too much and the toner blocking resistance is increased. The toner is softened by the heat of fusion in the developing process. Therefore, it is possible to obtain a desired resin for toner by changing the contents of the aromatic diol and the aliphatic diol according to the purpose, but in order to improve the toughness, the reactivity is increased to a high level. It is preferable to use a polyester resin having a molecular weight, and in order to maintain the fixing property of the toner, the aliphatic diol is preferably 20 to 80 mol%, more preferably 30 to 80 mol% with respect to the total acid component. Is the range.

Further, in the present invention, a polyfunctional carboxylic acid having a functionality of 3 or more is contained for the purpose of imparting an appropriate crosslinked structure to the polyester resin and improving the toughness. The trifunctional or higher polyvalent carboxylic acid used in the present invention includes:
Trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
1,2,5-hexanetricarboxylic acid, 1,2,7,8
-Octanetetracarboxylic acid, acid anhydrides and lower alkyl esters thereof, and the like. These trifunctional or higher polycarboxylic acids can be used alone or in combination of two or more. These trifunctional or higher polycarboxylic acids have the effect of increasing the toughness and glass transition temperature of the polyester resin and the effect of imparting cohesiveness to the polyester resin and increasing the offset resistance of the toner. May be appropriately selected according to the fixing temperature and copying speed of the copying machine, but from the viewpoint of toughness, it is 1 to 13 mol%, preferably 1 to 10 mol%. This is a polyfunctional carboxylic acid with 3 or more functional groups.
This is because if it is less than mol%, a sufficient crosslinked structure cannot be imparted to the polyester resin. Conversely, 13 mol%
If it exceeds, the reaction of the three-dimensional structure portion becomes preferential, and it becomes difficult to impart sufficient toughness to the polyester resin. That is, while the main chain of the polyester resin does not grow sufficiently, it reaches the gelation point and begins to form a stitch structure, so that the melt viscosity of the polyester resin itself becomes high, but the toughness decreases. The content of the trifunctional or higher polyvalent carboxylic acid is preferably 5 to 13 mol%, more preferably 5 to 10 mol, based on the total acid components when the trifunctional polycarboxylic acid is used. %, And when using a tetrafunctional or higher polyvalent carboxylic acid,
It is preferably 1 to 10 mol%, more preferably 1 to 7 mol% based on the total acid components.

Further, as the polyester resin composed of the above components, the toughness index is 250 to 6
It is necessary that the glass transition temperature is 00 μm and the glass transition temperature is 65 to 85 ° C. This is because when the toughness index of the polyester resin is less than 250 μm, the printing durability of the toner becomes insufficient, the toner is easily crushed, the charge amount changes, and a copy having a stable image density cannot be obtained. This is because, when it exceeds 600 μm, the fixing property is deteriorated, and it is preferably in the range of 350 to 550 μm, and more preferably in the range of 400 to 550 μm. The glass transition temperature of the polyester resin is 65 ° C.
When the temperature is less than 85 ° C., the toner is fused and the image is deteriorated in the toner charging step, and the toner adheres to the developing roll to contaminate the roll. This is because it decreases, and preferably 68 to 80.
It is in the range of ° C.

In order to impart toughness to the polyester resin as described above, the polyester resin is made to have an appropriate cross-linking structure, and structurally strong monomers such as terephthalic acid and aromatic diol are used to structurally By strengthening and increasing the number average molecular weight by using a highly reactive monomer such as an aliphatic diol, a toughness index of 25 is obtained.
It is possible to impart a high toughness of 0 to 600 μm.

In the present invention, the method of measuring the toughness index of the polyester resin is as follows.

The polyester resin pulverized product is sieved to prepare 50 g of a sample having a particle size of 1400 to 2000 μm.

30 g of the classified sample of is finely pulverized using a blender (TR-BL manufactured by Trio Science Co., Ltd.). 20 g of the finely pulverized product obtained by the operation of (scale 10:30 seconds) is weighed.

The weight of the sieve was measured so that the roughness of the sieve was 100 μm, 150 μm, 250 μm, 500 μm, 7
Assemble from below in the order of 10 μm and 1000 μm,
The finely pulverized product weighed in step 1 is put on the uppermost part of the screen, and vibrated for 30 minutes with a micro electromagnetic vibrating screener (M-2 type manufactured by Tsutsui Rikaki Co., Ltd.). (Scale 10) The resin on each sieve is weighed.

The resin weight on each sieve is plotted in a semi-logarithmic graph (cumulative weight of each mesh pass), and the particle size at which 50% by weight of the whole passes is read from the graph.

As the polyester resin of the present invention, from the viewpoint of imparting toughness to the polyester resin,
The number average molecular weight is preferably 3,000 to 30,000, more preferably 3,000 to 20,000. This is because if the number average molecular weight is less than 3000, the toughness of the polyester resin tends to decrease, and the printing durability as a toner tends to decrease.
This is because if the value exceeds 0, the fixability of the toner tends to decrease.

In the production of the polyester resin of the present invention, first, the monomer is charged into a reaction kettle and heated to raise the temperature to carry out an esterification reaction or a transesterification reaction. At this time, if necessary, a catalyst usually used for the esterification reaction or transesterification reaction of sulfuric acid, titanium butoxide, dibutyltin oxide, magnesium acetate, manganese acetate or the like can be used. Then, according to a conventional method, water or alcohol produced by the esterification reaction or transesterification reaction is removed. Following this, polymerization is carried out by a conventional method while distilling off the diol component under a reduced pressure of 150 mmHg or less.

In order to increase the toughness and glass transition temperature of the polyester resin, it is preferable that the charged molar ratio of the diol component to the acid component is 1.3 or less when the monomer is charged into the reaction vessel. The range is more preferably 1.2 or less. Further, if the molar ratio of the diol component is decreased, the reactivity of the polyester is lowered. Therefore, the esterification reaction or transesterification reaction may be performed at a high temperature of 250 ° C. or higher and a high pressure of about ^{2 to 4} kg / cm ² G. Preferably, more preferably 260 to
It is in the range of 275 ° C.

[0024]

The present invention will be described below with reference to examples, but the present invention is not limited thereto. In the examples, the glass transition temperature was measured by a scanning differential calorimeter (manufactured by Shimadzu Corporation) at a temperature rising rate of 5 ° C./min, and the tangent of the endothermic curve near the glass transition temperature and the contact point of the baseline were measured. Temperature. The number average molecular weight is a value measured by using 700 on a gel permeation chromatogram (manufactured by Tosoh Corporation). For the composition analysis, the polyester resin was hydrolyzed with hydrazine and quantified by liquid chromatography.

The non-offset fixing temperature means an initial density ID = 1.0 ± after a test image is formed by using a tester.
The 0.3 part was passed through a temperature-variable fixing roller with a speed of 100 mm / sec and a nip width of 8.0 mm, and the fixing part was peeled off the tape to obtain the density attenuation rate.
When the temperature of the fixing roller is raised, the fixing rate is 90%
The minimum fixing temperature was defined as the temperature exceeding the above.

The printing durability was evaluated by visually observing the image change after copying 5000 sheets using a copying machine having a non-magnetic one-component developing system according to the following criteria. A: A clear image was obtained from the beginning to the end. B: There was a slight change in the image density on the way, but it was judged to be good throughout. C: Good images were obtained up to 1000 copies. D: Image quality deteriorated at the initial stage.

Examples 1 to 7 The dicarboxylic acid component, the diol component, and the polyfunctional carboxylic acid component having three or more functional groups were charged into a reaction vessel having a distillation column with the charging composition shown in Table 1. Next, 0.08% by weight of dibutyltin oxide was added as a catalyst to the total acid component, the internal temperature of the reaction vessel was 260 ° C., and the stirring rotation speed was 20.
The esterification reaction was carried out for 3 hours under a pressure of 4 Kg / cm ² G while keeping it at 0 rpm. Then, the pressure in the reaction system was reduced to 1.0 mmHg over 30 minutes, and the internal temperature was kept at 240 ° C.
The condensation reaction was carried out for 2 hours while distilling ethylene glycol to obtain a pale yellow transparent polyester resin. The results of composition analysis of the obtained polyester resin are shown in Table 2. Also,
The glass transition temperature, toughness index and number average molecular weight of the obtained polyester resin were measured, and the results are shown in Table 2.

94 parts by weight of the obtained polyester resin, 5 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) and a charge control agent (Bontron S manufactured by Orient Chemical Co., Ltd.)
-34) 1 part by weight was premixed with a Henschel mixer and then 170% with an internal mixer.
Melt kneading was carried out under the conditions of ° C and 65 rpm. Next, this melt-kneaded product was cooled to room temperature, coarsely crushed with a hammer mill, and then pulverized with a git mill to a particle size of 22 μm or less. Then, using a wind force classifier, particle size 5 to 22 μm
Then, the toner was obtained by classification. The toner thus obtained was subjected to a fixing test and a printing durability test using a temperature variable type non-magnetic one-component printer, and the results are shown in Table 2.

[0029]

[Table 1]

[0030]

[Table 2]

As shown in Table 2, all of the toners using the polyester resin of the present invention as a toner resin are excellent in fixing property and printing durability and are suitable for a non-magnetic one-component developing system. there were.

Comparative Examples 1 to 9 Polyester resins were obtained in the same manner as in Example 1 except that the dicarboxylic acid component, the diol component and the polyfunctional carboxylic acid component having three or more functional groups were used in the charging composition shown in Table 3. . Table 4 shows the results of composition analysis of the obtained polyester resin. The glass transition temperature, toughness index and number average molecular weight of the obtained polyester resin were measured, and the results are shown in Table 4. A toner was obtained from the obtained polyester resin in the same manner as in Example 1. The obtained toner was subjected to a fixing test and a printing durability test using a temperature variable type non-magnetic one-component printer, and the results are shown in Table 4. Comparative Example 10 Polymerization was performed in the same manner as in Example 1 except that the esterification reaction was performed at 240 ° C. for 20 hours, but a sufficient esterification reaction product was not obtained.

[0033]

[Table 3]

[0034]

[Table 4]

As shown in Table 4, the toner of Comparative Example 1 was inferior in printing durability because of its low glass transition temperature. In Comparative Example 2, since the amount of the aromatic diol used was large, the polymer was inferior in reactivity and a polymer having a sufficient crosslinked structure could not be obtained, and the toughness was low and the printing durability was inferior. In Comparative Example 3, the toughness was too high and the fixability was extremely lowered. In Comparative Example 4, a sufficient crosslinked structure could not be imparted, the toughness was low and the printing durability was poor. In Comparative Example 5, the amount of trifunctional or higher polyvalent carboxylic acid used was large,
The toughness decreased and the printing durability was poor. Comparative Example 6
However, since the charged molar ratio of the diol component was high, the glass transition temperature and the toughness were significantly lowered, and the printing durability was poor. In Comparative Example 7, since the amount of the aromatic diol used was large, the reactivity was poor and a polymer having a sufficient crosslinked structure could not be obtained, and the toughness was low and the printing durability was poor. In Comparative Example 8, the glass transition temperature was low and the printing durability was poor because the amount of the aromatic diol used was small. In Comparative Example 9, since the amount of terephthalic acid used was small, the glass transition temperature was low and the printing durability was poor.

The symbols shown as compositions in Tables 1 to 4 are as follows.

TPA: terephthalic acid IPA: isophthalic acid ADA: adipic acid TMA: trimellitic acid PMA: pyromellitic acid EG: ethylene glycol BPP: polyoxypropylene (2.3) -2,2
-Bis (4-hydroxyphenyl) propane BPE: polyoxyethylene (2.3) -2,2-
Hydrogenated bis (4-hydroxyphenyl) propane BP: Hydrogenated bisphenol A

[0038]

The polyester resin for toner of the present invention is
It has a relatively high glass transition temperature, excellent toughness and printing durability, and excellent fixing properties, and is particularly effective for a non-magnetic one-component developing system.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-40470 (JP, A) JP-A-1-155362 (JP, A) JP-A-4-70670 (JP, A) JP-A-2- 225520 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 9/087

Claims (6)

(57) [Claims] 1. A dicarboxylic acid component containing terephthalic acid as a main component, a diol component containing an aromatic diol and an aliphatic diol, and 1 to 13 mol% of 3 relative to the total acid component.
A polyester resin comprising a polycarboxylic acid having a functionality or higher, a toughness index of 250 to 600 µm, and a glass transition temperature Tg of 65 to 85 ° C. 2. The number average molecular weight of the polyester resin is 30.
The polyester resin for toner according to claim 1, wherein the polyester resin is from 0 to 30,000. 3. The content of the aliphatic diol is 20 to 80 mol% with respect to the total acid component.
The polyester resin for toner described. 4. A dicarboxylic acid component containing terephthalic acid as a main component, a diol component containing an aromatic didiol and an aliphatic diol, and 1 to 13 mol% of a trifunctional or more polyfunctional carboxylic acid with respect to the total acid component. And are mixed so that the molar ratio of the diol component to the acid component is 1.3 or less, and 25
After the esterification reaction or the transesterification reaction at a temperature of 0 ° C. or higher, the polymerization reaction is performed, and the toughness index is 25.
A method for producing a polyester resin for toner, comprising producing a polyester resin having a glass transition temperature Tg of 0 to 600 μm and a glass transition temperature Tg of 65 to 85 ° C. 5. A polyester resin having a number average molecular weight of 30.
The method for producing a polyester resin for toner according to claim 4, wherein the polyester resin is from 0 to 30,000. 6. The aliphatic diol content is 20 to 80 mol% with respect to the total acid components.
A method for producing the polyester resin for a toner according to the above.