JP3418235B2 - Crosslinked 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 dry toner used for developing an electrostatic charge image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing and the like. More specifically, it relates to a crosslinked polyester resin for toner, which is excellent in low-temperature fixability, blocking resistance, offset resistance, and positive chargeability.

[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 in advance by friction. Is fixed. In the case of a magnetic latent image,
The latent image on the magnetic drum is developed with toner containing a magnetic material and then fixed. For fixing, the toner image obtained by development is directly fused on the photoconductive photoreceptor or the electrostatic recording body, or the toner image is transferred onto paper or film and then fused onto the transfer sheet. Done by.
Toner image fusion is performed by contact with solvent vapor, pressurization and heating, and there are two types of heating method: non-contact heating method using an electric oven and pressure heating method using a pressure roller. Recently, the latter is mainly used.

Toner used in the dry developing system is 1
There are two-component toners and two-component toners. The two-component toner is prepared by first melt-kneading a resin, a colorant, a charge control agent and other necessary additives to sufficiently disperse them, and then roughly pulverizing them.
Then, it is pulverized and classified into a predetermined particle size range to be manufactured. The one-component toner is manufactured in the same manner by adding magnetic iron powder in addition to the respective components of the above two-component toner.

Since the resin is the main component in the toner formulation, it controls most of the performance required for the toner. Therefore, the toner resin is required to have good dispersibility of the colorant in the melt-kneading step and good pulverizability in the pulverizing step in the toner production, and in the use of the toner, fixability, offset property, Versatile performance such as good blocking property and good electrical property is required. Epoxy resins, polyester resins, polystyrene resins, methacrylic resins and the like are known as resins used in the production of toners, but for pressure-bonding and heat-fixing methods, copolymers of styrene and (meth) acrylic acid ester are mainly used. Has been used.
However, polyester resins are attracting attention because they can be fixed at a lower temperature and the fixed toner image has excellent resistance to PVC plasticizer.

The polyester resin is originally suitable for negative charging toner because it has a property of being negatively charged, but in order to finish it as a toner for positive charging, a large amount of expensive charge control agent is used or a positive charge controlling agent is used. A method of blending a small amount of styrene-acrylic resin having a high charge amount has been used. From this, it is strongly desired to develop a toner resin having a high positive charge amount even when used alone without sacrificing the low-temperature fixing performance and the non-offset property.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a crosslinked polyester resin for toner which is excellent in fixability and blocking resistance and which can obtain a high positive charge when made into a toner.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a crosslinked polyester resin containing a specific polypropylene glycol as a polymer component can achieve the object, The present invention has been completed. That is, the present invention provides (a) at least one of an aromatic dicarboxylic acid component, (b) a trivalent or higher polyvalent carboxylic acid component and / or a polyhydric alcohol component,
(C) Aromatic diol component, (d) Ethylene glycol component, and (e) Weight average molecular weight Mw 500 to 200
A non-linear polycondensate composed of a polypropylene glycol component of 0, an acid value of 0.5 to 12 mgKOH / g, and a glass transition temperature Tg (hereinafter abbreviated as Tg) of 40 to.
It is a crosslinked polyester resin for toner, which has a softening temperature of 65 ° C. or lower and 145 ° C. or lower.

The present invention will be described in detail below. The aromatic dicarboxylic acid (a) used in the present invention is
It is selected from aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and lower alkyl esters thereof. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include dimethyl terephthalic acid, dimethyl isophthalic acid, diethyl terephthalic acid, diethyl isophthalic acid, dibutyl terephthalic acid, dibutyl isophthalic acid, etc. Terephthalic acid and dimethylisophthalic acid are preferred. The above aromatic dicarboxylic acid raises Tg and contributes to the improvement of blocking resistance, and because of its hydrophobic property, it is also effective for moisture resistance. Therefore, the aromatic dicarboxylic acid is contained in an amount of 60 mol% or more, preferably 70% by mole, based on all acid components.
Used in mol% or more. Among the aromatic dicarboxylic acids, the isophthalic acid type has the effect of enhancing the reactivity, but from the viewpoint of cost, it is preferable to use 50 mol% or less of all the acid components,
Further, terephthalic acid is effective in increasing the Tg of the resin, and it is preferably used in an amount of 50 mol% or more based on all acid components. The component (a) is used alone or in combination of two or more.

The trivalent or higher polycarboxylic acid and / or the polyhydric alcohol (b) used in the present invention.
Is selected from trivalent or higher polycarboxylic acids and polyhydric alcohols. Examples of trivalent or higher polycarboxylic acids include 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-octane tetracarboxylic acid and these acid anhydrides can be mentioned. Examples of polyhydric alcohols are sorbitol, 1,2,3,6-hexatetralol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1, 2, 5
-Pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like. The above-mentioned component (b) is used alone or in combination of two or more, and has the effect of increasing the Tg of the resin obtained, and also has the effect of imparting cohesiveness to the resin and increasing the offset resistance. It is preferably used in the range of 0.5 to 30 mol% with respect to the acid component. This is because if the component (b) is less than 0.5 mol%, a sufficient effect cannot be obtained, and if it exceeds 30 mol%, it is difficult to control gelation during production of the polyester resin, and the desired resin is not obtained. This is because it tends to be difficult to obtain.

As the aromatic diol (c) used in the present invention, at least one kind of aromatic diol represented by the following general formula (I) is preferably used.

[0011]

[Chemical 1] Examples of the aromatic diol represented by the formula (I) 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-
Examples thereof include bis (4-hydroxyphenyl) propane, and these are used alone or in combination of two or more. Since the aromatic diol (c) has an effect of increasing the Tg of the resin, it has good blocking resistance.

The amount of the aromatic diol component (c) used is preferably 80 mol% or less based on the total acid component,
If it is used in excess of mol%, the reactivity becomes extremely low and the productivity deteriorates.

Examples of the aliphatic diol (d) used in the present invention include ethylene glycol, neopentyl glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, hydrogenated bisphenol A and the like. From the viewpoint of fixability, ethylene glycol and neopentyl glycol are preferable. In particular, since ethylene glycol can increase the reactivity, it is preferably 20 mol% or more with respect to all acid components.

Further, in the present invention, polypropylene glycol (e) is added to the above (a) to (a) to reduce the negative chargeability of the conventional toner resin made of polyester resin.
It is polycondensed with the component (d).

The amount of polypropylene glycol (e) used is preferably in the range of 0.5 to 10% by weight, more preferably 2 to 7% by weight, based on the total amount of crosslinked polyester resin. This is because when the amount of polypropylene glycol (e) used is less than 0.5% by weight, the amount of negative charge of the crosslinked polyester resin tends to increase, and when it exceeds 10% by weight, Tg tends to decrease. . Further, in the present invention, the weight average molecular weight Mw of polypropylene glycol (e) needs to be in the range of 500 to 2000. This is because when the weight average molecular weight Mw is less than 500, the Tg of the resin is significantly lowered, while when the weight average molecular weight Mw exceeds 2000, the copolymerizability with other components tends to be lowered, and it is preferable. 10
The range is from 00 to 2000.

Further, in the present invention, a polymerization component other than those described above can also be used in combination depending on the required performance thereof within a range not impairing the object of the present invention. Generally, a known monomer as a raw material for the polyester resin may be used as long as the effect of the present invention is maintained. For example, as the dicarboxylic acid component, sebacic acid, isodecyl succinic acid, fumaric acid, adipic acid, and their monomethyl, monoethyl, dimethyl, diethyl ester and the like can be used.

These divalent carboxylic acids affect the fixing property and blocking resistance of the toner. That is,
When aromatic terephthalic acid or isophthalic acid is used, blocking resistance is improved, but fixing property is lowered. vice versa,
Aliphatic sebacic acid and adipic acid improve the fixability, but lower the Tg and thus the blocking resistance. In the case of aliphatic acids, this tendency is stronger as long-chain monomers. Therefore, it is necessary to use these characteristics in consideration.

In the production of the crosslinked polyester resin for toner of the present invention, the above-mentioned polymerization components (a) to (e) are charged into a reaction kettle, heated and heated to carry out an esterification reaction or a transesterification reaction. At this time, if necessary, an esterification catalyst or a transesterification catalyst used in a usual esterification reaction or transesterification reaction such as sulfuric acid, titanium butoxide, dibutyltin oxide, magnesium acetate, manganese acetate can be used. . Then, water or alcohol generated in the reaction is removed according to a conventional method. After that, the polymerization reaction is continuously carried out.
Polymerization is carried out under a vacuum of 50 mmHg or less while distilling off 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 catalyst amount are not particularly limited, and may be arbitrarily set as needed.

The crosslinked polyester resin comprising the non-linear polycondensation polymer of the present invention can be obtained by gelling the above polymerization components (a) to (e).

The crosslinked polyester resin for toner of the present invention has an acid value of 0.5 to 12 mgKOH / g, preferably 3
-8 mgKOH / g, Tg 40-65 ° C, preferably 50-60 ° C, softening temperature 145 ° C or less, preferably 1
It is necessary to have a physical property value of 25 to 145 ° C. This is because when the acid value is less than 0.5 mgKOH / g, the productivity of the resin is significantly reduced, while the acid value is 12 mgKOH / g.
If it exceeds / g, the amount of negative charge becomes too high, and the effect of copolymerizing polypropylene glycol disappears,
If Tg is less than 40 ° C, blocking resistance is poor,
On the other hand, when Tg exceeds 65 ° C., the blocking resistance is good, but the fixing performance remarkably deteriorates, and when the softening temperature exceeds 145 ° C., the fixing property deteriorates.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples. The performance evaluations in Examples and Comparative Examples were performed using the following methods.

(1) The acid value resin is heated and dissolved in benzyl alcohol and then cooled to 1
It was measured by titrating with a KOH benzyl alcohol solution of / 50 N.

(2) Tg (glass transition point) (° C.) Using a differential scanning calorimeter manufactured by Shimadzu Corporation, a temperature rise of 5 ° C.
The contact point between the base line and the tangent line of the endothermic curve in the vicinity of Tg when measured in / min was defined as Tg.

(3) Softening temperature (° C.) Shimadzu Corporation Flow Tester (CFT-50)
0) was used as the softening temperature (° C.) when the sample half flowed out under the conditions of nozzle 1.0 mmφ × 10 mmL, load 30 kg, temperature increase 3 ° C./min, sample amount 1.0 g.

(4) Weight average molecular weight Mw Measured by GPC HCL-8200 manufactured by Tosoh Corporation.

(5) Composition analysis The resin was hydrolyzed with hydrazine and quantified by liquid chromatography.

(6) Charge amount (μC / g) The sample was roughly pulverized with a hammer mill and then pulverized with a jet mill (manufactured by Nippon Pneumatic Co., Ltd.) to 20 μm or less. After that, wind force classifier (made by Nippon Pneumatic)
Was used to adjust the particle size to 5 to 20 μm. A carrier (TEFV-200 / 300 manufactured by Powder Tech Co., Ltd.) is mixed so that the obtained resin powder has a concentration of 3% by weight,
After acclimatizing to the environment for 48 hours in a thermo-hygrostat at 60% RH, the mixture was stirred for 20 minutes, and the charge amount was measured with a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co., Ltd.).

(7) Non-offset fixing temperature range (° C.) The toner is evenly sprinkled on the paper (initial density ID = 1.
0 ± 0.3), and pass through a variable temperature fixing roller. Next, the tape is peeled off from the fixed portion to obtain the density attenuation rate.
When the temperature of the roller was raised, the temperature at which the fixing rate exceeded 90% was defined as the minimum fixing temperature. Further, the temperature at which the toner began to adhere to the heat roller when the temperature was further raised was taken as the high temperature offset start temperature. The area between the lowest fixing temperature and the high temperature offset start temperature was defined as the feasible area (non-offset fixing temperature range). The speed of the fixing roller is 100
mm / min, and the nip width was set to 8.0 mm for evaluation.

(8) Blocking resistance 5 g of toner was placed in a 50 ml glass sample bottle,
After being left in a high-temperature bath at 50 ° C. for 50 hours, it was cooled to room temperature and the degree of aggregation was observed. The degree of aggregation was evaluated by the following method. In addition, in the present invention, it was judged that those having aggregation degrees A, B and C could be used. A: The toner drops just by turning the sample bottle upside down. B: The toner drops just by turning the sample bottle upside down and shaking it lightly. C: The toner drops when the sample bottle is turned upside down and tapped lightly. D: The toner drops when the sample bottle is turned upside down and strong vibration is given. E: The toner does not drop even when the sample bottle is turned upside down and strong vibration is applied.

The abbreviations used in Examples and Comparative Examples represent the following. Diol A: Polyoxypropylene (2.3) -2,2
-Bis (4-hydroxyphenyl) propane PPG-400: polypropylene glycol PPG-700 having a weight average molecular weight Mw of 400: polypropylene glycol PPG-1000 having a weight average molecular weight of Mw 700: polypropylene glycol PPG-1500 having a weight average molecular weight of Mw 1000: weight average molecular weight Mw 1500 Polypropylene glycol PPG-3000: polypropylene glycol having a weight average molecular weight of Mw 3000

Example 1 The amounts of terephthalic acid, isophthalic acid, trimellitic acid, diol A and ethylene glycol shown in Table 1 were charged into a reaction vessel equipped with a distillation column. Furthermore, 5% by weight of polypropylene glycol (Mw 1000) based on the calculated synthetic polymer amount and 0.03 part by weight of dibutyltin oxide as a catalyst were added to the total acid component, and the internal temperature was adjusted to 260.
The esterification reaction was carried out under normal pressure for 5 hours while maintaining the stirring temperature at 200 rpm and the stirring speed. Then, the pressure in the reaction system was reduced to 1.0 mmHg over 30 minutes, the internal temperature was kept at 240 ° C., the condensation reaction was performed for 2 hours while distilling ethylene glycol to cause gelation, and a light yellow transparent resin R-1 was obtained. Table 1 shows the compositional analysis results and resin physical property values of the obtained resin.

[0033]

[Table 1]

Next, with respect to 94 parts by weight of Resin R-1 obtained, carbon black (# 40 manufactured by Mitsubishi Kasei Co., Ltd.) was used.
5 parts by weight, charge control agent (manufactured by Orient Chemical Industry Co., Ltd.,
After premixing 1 part by weight of Bontron NO1) with a Henschel mixer, melt kneading was performed using an internal mixer manufactured by Kurimoto Iron Works Co., Ltd. at 170 ° C. and 65 rpm. After the melt-kneaded product is cooled to room temperature, it is roughly pulverized with a hammer mill and then 20 μm with a jet mill.
Crushed to the following. Thereafter, using a pneumatic classifier manufactured by Nippon Pneumatic Co., Ltd., toner T-1 having a particle size of 5 to 20 μm is used.
Got Table 2 shows the charge amount, the fixing test result, and the blocking resistance test result of Toner T-1. As is clear from Table 2, the toner T-1 has good offset resistance and blocking resistance, and has high positive chargeability.

[0035]

[Table 2]

Examples 2 to 3 Resins R-2 to R-3 were obtained in the same manner as in Example 1 except that the composition charged in polymerization was as shown in Table 3. Resin R
Table 3 shows the composition analysis results and resin physical property values of −2 to R-3.

[0037]

[Table 3]

Next, using the above resins R-2 to R-3,
The same operations as in Example 1 were performed to obtain toners T-2 to T-3. Table 4 shows the results of the charging properties, the offset resistance test and the blocking resistance test of the obtained toners T-2 to T-3. From Table 4, it is understood that the toners T-2 to T-3 have good offset resistance and blocking resistance, and have a high positive charge amount.

[0039]

[Table 4]

Examples 4 to 5 Resins R-4 to R-5 were obtained in the same manner as in Example 1 except that the composition for polymerization was changed as shown in Table 5. Resin R
Table 5 shows the compositional analysis results and resin physical property values of -4 to R-5.

[0041]

[Table 5]

Next, using the above resins R-4 to R-5,
The same operations as in Example 1 were performed to obtain toners T-4 to T-5. Table 6 shows the results of the charge amount, the offset resistance test, and the blocking resistance test of the obtained toners T-4 to T-5. From Table 6, it is understood that the toners T-4 to T-5 have good offset resistance and blocking resistance, and high positive chargeability.

[0043]

[Table 6]

Comparative Examples 1 to 3 Resins R-6 to R-8 were obtained in the same manner as in Example 1 except that the composition for polymerization was as shown in Table 7. Resin R
Table 7 shows the composition analysis results and resin physical property values of −6 to R-8.

[0045]

[Table 7]

Next, using the above resins R-6 to R-8,
The same operations as in Example 1 were performed to obtain toners T-6 to T-8. The results of the charge amount, offset resistance test and blocking resistance test of the obtained toners T-6 to T-8 are shown in Table 8.
Shown in. Since the toner T-6 has a high acid value, the positive charge amount was reduced. Toner T-7 contained a large amount of polypropylene glycol and thus had a low Tg and poor blocking resistance. High temperature offset occurred at 160 ° C.
Toner T-8 did not use polypropylene glycol, so the positive charge amount decreased.

[0047]

[Table 8]

Comparative Examples 4 to 6 Resins R-9 to R-11 were obtained in the same manner as in Example 1 except that the composition for polymerization was as shown in Table 9. Table 9 shows the analysis results and the physical properties of the resins R-9 to R-11. The resin R-10 was not able to be taken out of the reactor because the gelation occurred rapidly during the reaction.

[0049]

[Table 9]

Next, the same operations as in Example 1 were carried out using the above resins T-9 and T-11 to obtain toner T-9 and toner T-11. Obtained Toner T-9 and Toner T
Table 10 shows the results of the charge amount of -11, the offset resistance test, and the blocking resistance test. Toner T-9 has no non-offset fixing temperature range because it does not use a polyfunctional component, and Toner T-11 has a resin softening temperature of 1
The temperature was as high as 70 ° C and the blocking resistance was good, but the minimum fixing temperature rose to 165 ° C.

[0051]

[Table 10]

Comparative Examples 7 to 8 The same operations as in Example 1 were carried out except that the composition for polymerization was set as shown in Table 11. In the case of the resin R-13, since polypropylene glycol having a molecular weight Mw of 3000 was used,
The compatibility was poor and the polymerization mixture separated into two layers. Resin R-
Table 11 shows the results of composition analysis of 12 and the physical properties of the resin.

[0053]

[Table 11]

Next, using the above resin R-12, Example 1 was prepared.
The same operation as the above was performed to obtain Toner T-12. Table 12 shows the results of the charge amount, the offset resistance test and the blocking resistance test. Toner T-12 used a low molecular weight polypropylene glycol, and thus had a low Tg and poor blocking resistance. In addition, the amount of positive charge did not increase.

[0055]

[Table 12]

[0056]

As described above, the crosslinked polyester resin for toner according to the present invention is obtained by polycondensation of polypropylene glycol having a specific molecular weight to obtain low temperature fixability,
It has excellent blocking resistance, anti-offset property and positive charging property, and is useful as a dry toner resin used for developing an electrostatic image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoichi Nagai, 2-1, Ushikawa-dori, Toyohashi-shi, Aichi 2 Mitsubishi Rayon Co., Ltd. Toyohashi Plant (72) Inventor Junya Nakamura, 4-chome, Ushikawa-dori, Toyohashi-shi, Aichi No. 2 Mitsubishi Rayon Co., Ltd. Toyohashi Plant (56) References JP-A-63-68849 (JP, A) JP-A-63-68853 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB) Name) G03G 9/087

Claims (2)

(57) [Claims] 1. (a) Aromatic dicarboxylic acid component, (b)
At least one polyhydric carboxylic acid having a valence of 3 or more and / or a polyhydric alcohol component, (c) an aromatic diol component,
A non-linear polycondensate comprising (d) an aliphatic diol component and (e) a polypropylene glycol component having a weight average molecular weight Mw of 500 to 2,000 and having an acid value of 0.5 to.
12 mgKOH / g, glass transition temperature Tg is 40 to 65
C. and a softening temperature of 145.degree. C. or less, a crosslinked polyester resin for toner. 2. The crosslinked polyester resin for toner according to claim 1, wherein the (e) polypropylene glycol component is 0.5 to 10% by weight based on the total weight of the crosslinked polyester resin.