JPH10123756A - Polyester resin for toner, its production and electrophotographic toner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin for electrophotographic toner excellent in low temp. fixing property and off-set preventive effect. SOLUTION: The polyester resin for toner is obtained by allowing a linear polyester synthesized from polyoxypropylene bis-phenol A and a dicarboxylic acid to react with (1) a >=3-hydric alcohol and a dicarboxylic acid or (2) a >=3-carboxylic acid and a diol and contains <=5wt.% tetrahydrofuran(THF) insoluble portion. And the max. value (Mp) of the molecular weight of a THF soluble portion is controlled to 1-6×10<3> and the ratio (Mp)/(Mn) of (Mp) to the number average molecular weight (Mn) is controlled to 1-3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin for a toner, a method for producing the same, and an electrophotographic toner using the same.

[0002]

2. Description of the Related Art In recent years, as copiers and printers using an electrophotographic system have spread, the energy consumption (power consumption) has been reduced mainly for the purpose of dissemination to homes and multifunctional copiers or printers. Reduction), higher speed for the purpose of spreading to the so-called gray area located at the boundary between the printing machine and the copying machine, or lowering the roll pressure for simplifying the fixing roll to reduce the machine cost is desired. In addition, with the sophistication of copiers, copiers equipped with a two-sided copy function and an automatic document feeder have become widespread, and the fixing temperature of electrophotographic toner used in copiers and printers is low. Demand for electrophotographic toner with excellent offset resistance and excellent fixation strength on transfer paper to prevent the occurrence of stains during duplex copying and the occurrence of stains in the automatic document feeder It has been.

[0003] In response to these demands, the prior art has improved the molecular weight and molecular weight distribution of the binder resin as described below. Specifically, it is an attempt to achieve low-temperature fixing by reducing the molecular weight of the binder resin. However, in the case of toners using vinyl resins such as styrene and acrylic, the toner becomes brittle due to the reduction in molecular weight, and the toner is crushed and fused to the carrier and sleeve due to stress in the developing machine. Image deterioration due to changes in charging characteristics was inevitable. In addition, stains occurred during duplex copying and stains occurred in the automatic document feeder. On the other hand, in the case of reducing the molecular weight of a condensed resin represented by a polyester resin, although the melting point is lowered, the viscosity is also lowered and the offset phenomenon to the fixing roll occurs. In order to prevent this, a method of introducing a crosslinked structure to broaden the molecular weight distribution of the polyester resin has been attempted. However, in this method, the molecular weight distribution is widened by the crosslinking, and the offset phenomenon is suppressed, but the overall molecular weight is increased, and there is a problem that the low-temperature fixability is deteriorated. For this reason, the glass transition point temperature (Tg) of the resin had to be lowered for low-temperature fixing. in this way,
With conventional technology, while satisfying offset resistance and storage stability,
Low temperature fixability could not be achieved.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above-mentioned problems of the known toner, to fix the toner at a low temperature, to cause no problem in the offset property, and to improve the transfer paper. An object of the present invention is to provide an electrophotographic toner having excellent fixing strength to toner.

[0005]

According to the present invention, there is provided a diol component which is polyoxypropylene-modified bisphenol A, and at least one dicarboxylic acid selected from aromatic dicarboxylic acids, aliphatic dicarboxylic acids and alicyclic dicarboxylic acids. And at least one of a trihydric or higher polyhydric alcohol component and a trihydric or higher polycarboxylic acid component.
The total component ratio of the polyhydric alcohol component having a valency of 3 or more and the polycarboxylic acid component having a valency of 3 or more is 2.5 mol% or more and 10 mol% or less in the components of all monomers, and the functional group ratio of all components is COOH / OH = 0.7 to 0.95 or OH
/COOH=0.7 to 0.95, tetrahydrofuran (THF) -insoluble content is 5% by weight or less, and the maximum molecular weight (Mp) of THF-soluble component is 1 × 10 ³ or more and 6 × 1
0 ³ or less, a polyester resin for a toner, wherein the relationship between Mp and the number average molecular weight (Mn) is Mp / Mn = 1.0 to 3.0. The polyester resin of the present invention has an acid value of 5 mgKOH / g or less and a hydroxyl value of 60 mgKOH / g or less or an acid value of 60 mgKOH / g or less.
KOH / g or less and a hydroxyl value of 5 mg KOH / g
g or less.

[0006] The polyester resin for toner of the present invention comprises a line synthesized from polyoxypropylene bisphenol A and at least one dicarboxylic acid selected from aromatic dicarboxylic acids, aliphatic dicarboxylic acids and alicyclic dicarboxylic acids. A branched polyester resin obtained by reacting at least one of a trihydric or higher polyhydric alcohol and a trihydric or higher polycarboxylic acid as a cross-linking agent with a cross-linked polyester resin. (Solvent insoluble matter) is a resin synthesized so as not to generate as much as possible. That is, the component ratio of the trihydric or higher polyhydric alcohol component and the trihydric or higher polyhydric carboxylic acid component as the cross-linking agent is 2.5 mol% or more and 10 mol% or less in all the monomer components.
When this ratio is less than 2.5 mol%, the molecular weight distribution does not sufficiently increase, and offset occurs at a high temperature.
If it exceeds, the molecular weight increases, the viscosity increases, and the low-temperature fixability deteriorates. The functional group ratio of all components is COOH / O
H = 0.7 to 0.95 or OH / COOH = 0.7 to
0.95. If COOH / OH is less than 0.7, the molecular weight distribution does not sufficiently increase, not only does the toner have an offset at a high temperature, but also the hydroxyl value increases, thereby deteriorating moisture resistance and causing toner blocking. Becomes Conversely, if COOH / OH exceeds 0.95, the molecular weight increases, the melting start temperature increases, and the low-temperature fixability deteriorates. If OH / COOH is less than 0.7, the molecular weight distribution does not sufficiently increase, and a high-temperature offset occurs as a toner. On the other hand, if OH / COOH is more than 0.95, the molecular weight increases, the melting start temperature increases, and the low-temperature fixability deteriorates.

Further, when the THF-insoluble content is more than 5% by weight, the melt viscosity of the toner becomes too high and the fixing strength at a low temperature is lowered. 0% by weight of THF insoluble matter
Is most preferable for the low-temperature fixability. Also, TH
The maximum value (Mp) of the GPC molecular weight of the F-soluble component is 1 × 10
³ or more and 6 × 10 ³ or less, preferably 3 × 10 ³ or more and 6 ×
10 ³ or less. When Mp is less than 1 × 10 ³ , the resin strength becomes weak, and the life as a developer becomes short. Conversely, if it exceeds 6 × 10 ³ , the melting start temperature increases, and the low-temperature fixability deteriorates. Further, the number average molecular weight (Mn) and M
The relationship with p is Mp / Mn = 1.0 to 3.0, preferably Mp / Mn = 1.0 to 2.0. When Mp / Mn is less than 1.0, a high molecular weight substance is excessively contained, the melting start temperature increases, and the low-temperature fixability deteriorates. Conversely, if Mp / Mn exceeds 3.0, the amount of low molecular weight compounds will be excessive, the resin strength will be weakened, and the life as a developer will be shortened, or the amount of high molecular weight materials will be extremely reduced, and sufficient Viscosity cannot be obtained, and the offset resistance as a toner deteriorates.

[0008] The THF-insoluble component in the present invention is THF5
0.5 g of resin is put in 0 ml, and dissolved by heating at 60 ° C. for 3 hours, and an insoluble resin is filtered (Celite # 545).
Is filtered at 80 ° C. with a vacuum drier, and the weight of the dried resin is defined as Wd (g). The value calculated by insoluble matter (% by weight) = Wd / 0.5 × 100 Say. The molecular weight of the THF-soluble component of the polyester resin for a toner of the present invention is measured by gel permeation chromatography (hereinafter, referred to as GPC). In the present invention, the molecular weight distribution of the resin for toner may be measured by GPC under the following conditions by using 50 ml of a THF solution in which the resin obtained at the time of extracting the THF-insoluble component is dissolved. Value. The ratio of each molecular weight is a value obtained by analyzing a result of a chromatogram obtained by GPC and calculating from an integrated value in each molecular weight range. The GPC measurement was carried out by flowing a solvent (THF) at a temperature of 25 ° C. at a flow rate of 1 ml / min, and using a THF sample solution having a concentration of 0.4 gr / dl as a sample weight.
Inject mg and measure. When measuring the molecular weight of a sample, the molecular weight distribution of the sample is within a range in which the logarithm of the molecular weight and the count number of a calibration curve prepared from several types of monodisperse polystyrene standard samples are linear. Select In this measurement, the reliability of the measurement was determined based on the NBS706 polystyrene standard sample (Mw = 28.8 × 104, Mn = 13.7 × 10
4, Mw / Mn of 2.11) is 2.11 ±
It can be confirmed by being 0.10.

Next, a method for producing the polyester resin for a toner of the present invention will be described. The polyester resin for a toner of the present invention has a reaction of 1 × 10 ³ or more and 6 ×
After synthesizing a linear polyester having a maximum value of the molecular weight in a region of 10 ³ or less, one kind selected from a trivalent or more polyhydric carboxylic acid and a trivalent or more polyhydric alcohol as a second-stage reaction. It can be produced by mixing the above and one or more selected from diols and dicarboxylic acids and subjecting them to a polycondensation reaction.

Specifically, first, as a first-stage reaction, polyoxypropylene-modified bisphenol A and at least one dicarboxylic acid selected from aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids are used. Is subjected to a polycondensation reaction and Mp is applied to a region of 1 × 10 ³ or more and 6 × 10 ³ or less.
Is synthesized. At this time, if the Mp of the linear polyester is less than 1 × 10 ³ , the residual monomer is large, the glass transition temperature is lowered, and the glass transition temperature after the subsequent synthesis of the crosslinked resin is also lowered, so that the storage stability is deteriorated. On the other hand, if it exceeds 6 × 10 ³ , the molecular weight after synthesis of the crosslinked resin becomes too high, and the melting start temperature rises because Mp exceeds 6 × 10 ³ , and the final melting start temperature of the toner exceeds 105 ° C. Since the toner is not sufficiently melted by the fixing roll, the low-temperature fixability is deteriorated. The total of the acid value and the hydroxyl value of the linear polyester resin is 100 m
It is necessary to be less than gKOH / g. If the sum of the acid value and the hydroxyl value, that is, the number of terminal functional groups of the linear polyester exceeds 100 mgKOH / g, the overall molecular weight of the polyester resin for a toner obtained in the subsequent step increases, and the THF-insoluble content becomes large. By occurring
The viscosity increases and the low-temperature fixability deteriorates. Therefore, in order to keep the molecular weight of the polyester resin for toner low, to lower the melting start temperature and to maintain good low-temperature fixability, the total of the acid value and the hydroxyl value of the linear polyester resin is 100 mg.
KOH / g or less, and 50 mg KO
It is preferably at most H / g. The acid value and the hydroxyl value are values measured by the method described in JIS K0070.

The number of additions of the polyoxypropylene bisphenol A used for the synthesis of the linear polyester is from 2 to
6 can be arbitrarily selected. For example, bisphenol A propylene oxide 2 mol adduct, ie, [2,2'-bis [4- (2-hydroxy-2-propyleneoxy) phenyl] propane], bisphenol A
Propylene oxide 3 mol adduct, ie, [2,2 '
-Bis [4- (2-hydroxy-3-propyleneoxy) phenyl] propane, bisphenol A propylene oxide 4 mol adduct, that is, [2,2'-bis [4
-(2-hydroxy-4-propyleneoxy) phenyl] propane, bisphenol A propylene oxide 5 mol adduct, ie, [2,2'-bis [4- (2-hydroxy-5-propyleneoxy) phenyl] propane, bisphenol A 6 mol of propylene oxide adduct, ie, [2,2'-bis [4- (2-hydroxy-
6-propyleneoxy) phenyl] propane. Further, as the dicarboxylic acid, fumaric acid, maleic acid, succinic acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, adipic acid, sebacic acid , Dodecane diacid, 1,12-dodecane dicarboxylic acid, eicosane diacid, azelaic acid, brassic acid, naphthalenedicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, 2.3-piperazine dicarboxylic acid, iminodicarboxylic acid, Imidazole-4,5-dicarboxylic acid, piperidine dicarboxylic acid, pyrazole dicarboxylic acid, N-methylpyrazoledicarboxylic acid, N-phenylpyrazoledicarboxylic acid,
Pyridinedicarboxylic acid, carbazole-3,6-dicarboxylic acid, 9-methylcarbazole-3,6-dicarboxylic acid, carbazole-3,6-dibutyric acid, carbazole-
3,6-γ, γ′-diketobutyric acid, acid anhydrides thereof and lower alkyl esters thereof, and the like.

Next, as the second stage reaction, after the completion of the first stage reaction, the temperature is lowered, and then the linear polyester resin is selected from a trivalent or higher polyvalent carboxylic acid and a trivalent or higher polyhydric alcohol. The polycondensation reaction is carried out by mixing one or more of the above and one or more selected from diols and dicarboxylic acids and one or more selected from dicarboxylic acids and diols. At that time, the amount of the functional group is calculated as COOH / OH = 0.07 to 0.95 or OH / COOH = 0.7 to 0.95 in terms of the total monomer charge in the first and second stages. The monomer is added so that At this time, if the torque at the time of addition of the monomer added later is set to 1, then 2 to 2
The reaction is terminated when the torque reaches 5 times, preferably 3 to 5 times. In this case, the addition amount of the trivalent or higher polyvalent carboxylic acid and the trivalent or higher polyhydric alcohol is 2.5 mol% or more and 10 mol% or less based on all the raw material monomers. When the addition amount of the trivalent or higher polyhydric carboxylic acid and the trivalent or higher polyhydric alcohol is less than 2.5 mol%, the molecular weight distribution does not sufficiently increase, offset occurs at a high temperature, and 10 mol% If it exceeds, the molecular weight increases, the viscosity increases, and the low-temperature fixability deteriorates.

Further, the ratio of the functional groups in terms of the total monomer charge of the first stage and the second stage is COOH / OH = 0.
If it is less than 7, the hydroxyl value increases, so that the moisture resistance deteriorates, which causes blocking of the toner. Conversely, COOH
When / OH is more than 0.95, the residual acid value increases, and it is difficult to control the polycondensation reaction, which is not preferable. Also, OH
If / COOH is less than 0.7, the molecular weight distribution is not sufficiently increased, and a high-temperature offset occurs. OH / C
When OOH exceeds 0.95, the reaction proceeds too much, and it is difficult to control the polycondensation reaction, which is not preferable. By taking the second stage polycondensation step, a polyester resin for a toner having a small increase in molecular weight, that is, a low molecular weight can be formed even when a trivalent or higher polyvalent monomer is used. It is preferable to add the monomers used in the second-stage reaction at the same time or as short as possible in order to keep the molecular weight distribution within the target region. In addition,
In this case, the addition of the monomers used in the second stage reaction may be carried out simultaneously or as quickly as possible.
It is preferable because the molecular weight distribution is within a target region. When the torque at the time of adding the monomer added later is set to 1,
The reaction is terminated when the torque reaches 2 to 5 times the torque.
At this time, the acid value is 5 mgKOH / g or less, and the hydroxyl value is 60 mgKOH / g or less or the acid value is 60 mgKOH / g.
KOH / g or less and a hydroxyl value of 5 mg KOH / g
g or less is preferable. When the acid value exceeds 5 mg KOH / g and the hydroxyl value exceeds 60 mg KOH / g, or when the acid value exceeds 60 mg KOH / g and the hydroxyl value is 5 mg KO
If it exceeds H / g, the change in the physical properties of the resin after the completion of the reaction becomes large, and a resin having constant characteristics may not be obtained.

As the dicarboxylic acid and diol used in the second-stage polycondensation reaction, those exemplified during the synthesis of the linear polyester can be used. Examples of the trivalent or higher carboxylic acid include trimellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, pyridinetricarboxylic acid and pyridine-2. , 3,4
Examples thereof include 6-tetracarboxylic acid, 1,2,7,8-tetracarboxylic acid, butanetetracarboxylic acid, and the like, and acid anhydrides thereof and lower alkyl esters thereof can be used.

The polyhydric alcohols having 3 or more valent groups include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol,
2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 3,5-trihydroxybenzene and the like are exemplified.

Next, the electrophotographic toner of the present invention will be described. The electrophotographic toner of the present invention, in addition to the polyester resin, other resins, a colorant, a magnetic substance, a charge control agent, and other additives are mixed, and then melted and kneaded, pulverized,
It can be manufactured by classification. A super-mixer or the like is used for mixing, a single-screw extrusion kneader, a twin-screw extrusion kneader, an extruder, a roller mixer, a Banbury mixer, a pressure kneader, or the like is used for hot-melt kneading. A dry air classifier is used.

As the binder resin for the electrophotographic toner of the present invention, in addition to the polyester resin for the toner of the present invention, a styrene resin, a styrene acrylic copolymer resin, a polyester resin, a polyethylene resin, an epoxy resin, A resin such as a silicone resin, a polyamide resin, or a polyurethane resin may be blended.

The coloring agents used in the present invention include carbon black, aniline blue, phthalocyanine blue,
Quinoline yellow, malachite green, lamp black, rhodamine B, quinacridone and the like. The amount of the colorant added is 1 to 20% by weight based on the resin. As the charge control agent, a nigrosine dye, an ammonium salt, an azine or the like for a positively charged toner is used in an amount of 0.1 to
Add 10% by weight. A toner using a polyester resin generally gives a negative charge. When a charge control agent for a negative charge toner is added as necessary, a chromium complex, an iron complex, or the like is used. When the negative chargeability is too strong, it is possible to add the above positive charge control agent to neutralize the charge.

The magnetic material used in the electrophotographic toner of the present invention includes ferromagnetic metals or alloys such as ferrite and magnetite, cobalt, nickel and the like, and compounds containing these elements. Alloys that do not contain magnetic elements but become ferromagnetic when subjected to an appropriate heat treatment, such as alloys of the type called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum and manganese-copper-tin, Acid value chromium or the like can be used. These magnetic materials have an average particle size of 0.1.
It is uniformly dispersed in the binder resin in the form of fine powder of 1 μm. Its content is 20 to 7 parts per 100 parts by weight of toner.
0 parts by weight, preferably 40 to 70 parts by weight.

The toner for electrophotography of the present invention is mixed with a carrier made of ferrite powder, iron powder, or the like to form a two-component developer. When a magnetic material is contained, it may be used as it is as a one-component developer without being mixed with a carrier, or may be used as a two-component developer by being mixed with a carrier. Further, it can be used for a non-magnetic one-component developing method.

As for the melting characteristics of the electrophotographic toner, the melting start temperature is from 60 ° C. to 105 ° C., particularly from 60 ° C. to 1 ° C. in order to improve the fixability at a lower temperature.
00 ° C or lower is preferred. If the melting start temperature is lower than 60 ° C., the blocking property of the toner may be deteriorated and a problem may occur in storage stability. If it exceeds 105 ° C., the low-temperature fixability may be deteriorated, which is not preferable. In order to have a sufficient fixing temperature range (non-offset temperature range), it is preferable that the decrease in the melt viscosity at a high temperature is small, and the difference between the softening point and the melting start temperature is 15 ° C or more and 45 ° C or less. Is preferred. 1
When the temperature is lower than 5 ° C., the fixing temperature range becomes narrow, and when the temperature exceeds 45 ° C., the offset resistance can be maintained satisfactorily.

The above-mentioned melting start temperature means the temperature at which the plunger drops under the following measuring instrument and measuring conditions.
The softening point means a temperature at a middle point from a plunger descent start temperature to a descent end temperature. Measuring instrument; elevated flow tester CF-5 manufactured by Shimadzu Corporation
00, measurement conditions; plunger: 1 cm ² , die diameter: 1 m
m, die length: 1 mm, load: 20 kgF, preheating temperature: 50 to 80 ° C, preheating time: 300 sec, and heating rate: 6 ° C / min.

[0023]

EXAMPLES Hereinafter, a synthesis example of the resin of the present invention and an electrophotographic toner using the resin will be described in more detail.
In addition, the part in an Example means a weight part. Example 1 Bisphenol A propylene oxide 2 mol adduct 3
44 g (1 mol) and 149.4 g of terephthalic acid (0.9
Mol) and 0.05 g of dibutyltin oxide in glass 1
The mixture was placed in a 4-liter four-neck flask, fitted with a thermometer, a stirrer, a falling condenser, and a nitrogen inlet tube, heated with a mantle heater, and heated and stirred at a reaction temperature of 200 ° C. under a nitrogen stream. After the outflow of water was completed, the temperature was raised to 230 ° C. in about 1 hour, and the mixture was heated and stirred for 2 hours to synthesize a linear polyester resin. The maximum value (Mp) of the molecular weight of the THF-soluble component of this linear polyester resin is 4.2 × 10 ³ , and the total of the acid value and the hydroxyl value is 65 m.
gKOH / g. Next, take about 1 hour at 200 ° C
After cooling to 13.6 g of pentaerythritol (0.
1 mol), 20.5 g (0.06 mol) of eicosane diacid
And 0.6 g of dibutyltin oxide, and
The mixture was heated and stirred for hours. Thereafter, the temperature was raised to 220 ° C., and the mixture was heated and stirred for 2 hours. After the outflow of water was completed, the pressure in the reactor was reduced to 5 Torr, and the reaction was terminated when the torque reached four times that at the time of the addition of the monomer added later, to obtain a polyester resin A for toner. Mp of the polyester resin A is 4.5.
× 10 ³ , and the number average molecular weight (Mn) was 3.2 × 10 ³ .

Example 2 Bisphenol A propylene oxide 2 mol adduct 3
09.6 g (0.9 mol) and 166.1 g of isophthalic acid
(1 mol) and 0.05 g of dibutyltin oxide were placed in a 1-liter glass four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. Mp of this linear polyester resin was 4.3 × 10 ³ , and the total of the acid value and the hydroxyl value was 67 mgKOH / g. Next, 37.8 g (0.18 mol) of trimellitic acid and 27.5 mol of adduct of bisphenol A propylene oxide were added.
2 g (0.08 mol) and 0.5 g of dibutyltin oxide
Was charged, and the reaction was terminated at the time when the torque reached four times that at the time of addition of the monomer added later by the same operation as in Example 1 to obtain a polyester resin B for toner. Mp of this polyester resin B was 3.8 × 10 ³ and Mn was 2.8 × 10 ³ .

Example 3 Bisphenol A propylene oxide 2 mol adduct 3
44 g (1 mol) and 132.8 g (0.8%) of terephthalic acid
Mol) and 0.05 g of dibutyltin oxide in glass 1
The mixture was placed in a liter four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. The Mp of this linear polyester resin was 4.0 × 10 ³ , and the total of the acid value and the hydroxyl value was 78 mgKOH / g. Next, bisphenol A propylene oxide 2 mol adduct 3
4.4 g (0.1 mol) of butanetetracarboxylic acid 1
8.7 g (0.08 mol) and dibutyltin oxide 0.
5 g was charged, and the reaction was terminated at the time when the torque reached four times that at the time of addition of the monomer added later by the same operation as in Example 1 to obtain a polyester resin C for toner.
Mp of this polyester resin C is 5.2 × 10 ³ , Mn
Was 3.5 × 10 ³ .

Example 4 Bisphenol A propylene oxide 2 mol adduct 2
92.4 g (0.85 mol) and isophthalic acid 166.1
g (1 mol) and 0.05 g of dibutyltin oxide were placed in a glass 1-liter four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. Mp of this linear polyester resin was 4.1 × 10 ³ , and the total of the acid value and the hydroxyl value was 74 mgKOH / g. Next, 23.4 g of butanetetracarboxylic acid (0.1
Mol), 6.7 g of trimethylolpropane (0.00.5
Mol), bisphenol A propylene oxide 2 mol adduct 17.2 g (0.05 mol) and dibutyltin oxide 0.3 g were charged. The reaction was terminated when the torque reached doubled, and a polyester resin D for toner was obtained. Mp of this polyester resin D is 4.0 × 1
O ³ and Mn were 2.7 × 10 ³ .

Example 5 Bisphenol A propylene oxide 2 mol adduct 3
44 g (1 mol), terephthalic acid 149.4 g (0.9
Mol) and 0.05 g of dibutyltin oxide in glass 1
The mixture was placed in a liter four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. The Mp of this linear polyester resin was 4.8 × 10 ³ , and the total of the acid value and the hydroxyl value was 61 mgKOH / g. next,
21 g (0.1 mol) of trimellitic acid, 6.8 g (0.1 mol) of pentaerythritol, 12.9 g (0.05 mol) of 12-dodecanedicarboxylic acid, and 0.6 g of dibutyltin oxide were added. By the same operation as in 1, the reaction was terminated when the torque reached four times that of the addition of the monomer added later, and a polyester resin E for toner was obtained. Mp of this polyester resin E is 3.2 × 1
O ³ and Mn were 2.4 × 10 ³ .

Comparative Example 1 Bisphenol A propylene oxide 2 mol adduct 3
44 g (1 mol), 149.4 g of isophthalic acid (0.9
Mol) and 0.05 g of dibutyltin oxide in glass 1
The mixture was placed in a liter four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. Mp of this linear polyester resin was 4.3 × 10 ³ , and the total of the acid value and the hydroxyl value was 64 mgKOH / g. next,
6.7 g (0.05 mol) of trimethylolpropane, 23 g (0.1 mol) of dodecanedioic acid and 0.6 g of dibutyltin oxide were charged, and the same operation as in Example 1 was carried out.
The reaction was terminated when the torque reached 1.5 times that at the time of addition of the monomer added later, and a polyester resin F for toner was obtained. Mp of this polyester resin F is 4.3 × 1
O ³ and Mn were 2.0 × 10 ³ .

Comparative Example 2 Bisphenol A propylene oxide 2 mol adduct 3
44 g (1 mol), 166.1 g (1 mol) of terephthalic acid and 0.05 g of dibutyltin oxide were placed in a 1-liter glass four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. The Mp of this linear polyester resin was 4.8 × 10 ³ , and the total of the acid value and the hydroxyl value was 72 mgKOH / g. Next, 27.2 g (0.2 mol) of pentaerythritol, 23.4 g (0.1 mol) of butanetetracarboxylic acid, 34.2 g (0.1 mol) of eicosandioic acid and 0.6 g of dibutyltin oxide were added. Then, by the same operation as in Example 1,
When the resin was wound around the stirrer, the reaction was stopped to obtain a polyester resin G for toner. Mp of the polyester resin G was 8.9 × 10 ³ and Mn was 2.8 × 10 ³ .

Comparative Example 3 Bisphenol A propylene oxide 2 mol adduct 2
75.2 g (0.8 mol), 166.1 g of terephthalic acid
(1 mol) and 0.05 g of dibutyltin oxide were placed in a 1-liter glass four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. Mp of this linear polyester resin was 2.3 × 10 ³ , and the total of the acid value and the hydroxyl value was 80 mgKOH / g. Next, 20.4 g (0.15 mol) of butanetetracarboxylic acid, 20.64 g (0.06 mol) of a 2 mol adduct of bisphenol A propylene oxide and 0.6 g of dibutyltin oxide were charged, and the same as in Example 1 was carried out. By the above operation, the reaction was stopped when the resin was wound around the stirrer, and a polyester resin H for toner was obtained. Mp of this polyester resin H was 7.8 × 10 ³ , and Mn was 2.5 × 10 ³ .

Comparative Example 4 Bisphenol A propylene oxide 2 mol adduct 3
44 g (1 mol), 166.1 g (1 mol) of isophthalic acid and 0.05 g of dibutyltin oxide were placed in a 1-liter glass four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. The Mp of this linear polyester resin was 4.8 × 10 ³ , and the total of the acid value and the hydroxyl value was 82 mgKOH / g. Next, 26.8 g (0.2 mol) of trimethylolpropane and 1,
64.5 g (0.25 mol) of 12-dodecanedicarboxylic acid and 0.6 g of dibutyltin oxide were charged, and the reaction was stopped at the time when the resin was wound around the stirrer by the same operation as in Example 1, and the polyester resin for toner was used. I was obtained.
Mp of this polyester resin I is 5.9 × 10 ³ , Mn
Was 2.4 × 10 ³ .

Comparative Example 5 Bisphenol A ethylene oxide 2 mol adduct 3
16 g (1 mol), 166.1 g of isophthalic acid (0.9
Mol) and 0.05 g of dibutyltin oxide in glass 1
The mixture was placed in a liter four-necked flask, and a linear polyester resin was synthesized in the same manner as in Example 1. The Mp of this linear polyester resin was 8.5 × 10 ³ , and the total of the acid value and the hydroxyl value was 53 mgKOH / g. next,
13.6 g (0.1 mol) of pentaerythritol, 20.5 g (0.06 mol) of eicosane diacid and 0.6 g of dibutyltin oxide were charged, and the resin was wound around the stirrer in the same manner as in Example 1. At this point, the reaction was stopped to obtain a polyester resin J for toner. Mp of this polyester resin J is 11.0 × 10 ³ , Mn is 12.0 × 10 3
^{Was 3} .

Next, the polyester resins for toner of the Examples and Comparative Examples and other raw materials were mixed in a supermixer at the following mixing ratio, melt-kneaded, crushed and classified to obtain an average particle diameter of 1: 1.
After obtaining particles of 1 μm, 0.3 parts of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was adhered to the resin using a Henschel mixer to obtain a negatively chargeable electrophotographic toner. Table 1 shows the evaluation results of characteristic values such as Tg of these electrophotographic toners.

The following tests were carried out using the electrophotographic toners obtained in the above Examples and Comparative Examples. (1) Non-offset temperature region and non-offset temperature range 4 parts of toner for electrophotography and ferrite carrier without resin coating (FL-1020 manufactured by Powder Tech) 9
Six parts were mixed to prepare a two-component developer. Using this developer, a commercially available copying machine (Z-13 manufactured by Sanyo Electric Co., Ltd.)
According to 3), a plurality of belt-shaped unfixed images each having a length of 2 cm and a width of 5 cm were prepared on A4 transfer paper. Next, a fixing device in which a heat fixing roll having a surface layer formed of Teflon and a pressure fixing roll having a surface layer formed of silicone rubber rotate in pairs, a roll pressure of 1 kg / cm ² and a roll speed of 200 mm / The surface temperature of the heat fixing roll was changed stepwise to fix the toner image on the transfer paper having the unfixed image at each surface temperature. At this time, observation was made as to whether or not toner stains occurred in the blank portion. A temperature region where no stains occurred was defined as a non-offset temperature region, and a difference between the maximum value and the minimum value of the non-offset temperature region was defined as a non-offset temperature width.

(2) Fixing Strength The surface temperature of the heat fixing roll of the fixing machine was set to 130 ° C., and the toner image on the transfer paper on which the unfixed image was formed was fixed. Then, after measuring the image density of the formed fixed image using a reflection densitometer (RD-914, manufactured by Macbeth Co., Ltd.), the fixed image is rubbed with a cotton pad, and then the image is similarly formed. The concentration was measured. From the obtained measured values, the fixing strength was calculated according to the following formula, and was used as an index for the low-temperature fixing toner. Table 1 shows the results.

## EQU1 ## Fixing strength = (image density of fixed image after rubbing / image density after rubbing) × 100

[0036]

[Table 1]

As is clear from the results shown in Table 1, the non-offset temperature region of the electrophotographic toner of the present invention has no offset from a low temperature to a high temperature and has a non-offset temperature width of 100 ° C. or more. Thus, it was confirmed that a practically sufficient range was maintained. 130 ° C
Since the fixing strength at a fixing temperature of 80% or more was 80% or more and had a practically sufficient fixing strength, it was confirmed that the fixing ability was excellent at low temperature. Furthermore, the image density of the developed image was sufficient, and there was no fogging of the non-image portion, which was practically sufficient. In addition, a continuous copy test was performed on up to 10,000 sheets using each of the developers and the copying machine of the embodiment described in (1) above. As a result, in all the examples, the frictional charge measured by a blow-off frictional charge measuring device (manufactured by Toshiba Chemical Co., Ltd.) changed from −25 μc / g to −29 μc / g from the initial stage to 10,000 sheets. The image density was maintained at 1.4 or more in the process of continuous copying from the initial stage to 10,000 sheets, and the background fog of the non-image area measured by a color difference meter (Z-1001DP manufactured by Nippon Denshoku Co., Ltd.) was also 0. 6 or less, which confirmed that there was no practical problem. Further, even if the toner is left at 50 ° C. for 2 days,
No blocking or caking was observed.

[0038]

The polyester resin for a toner according to the present invention comprises:
Because a low-molecular-weight polyester resin with a low melt viscosity has a certain high-molecular-weight component with a low solvent-insoluble content,
When the toner is used, the offset phenomenon can be prevented. Also,
Since the low molecular weight compound is controlled within a certain range, an increase in the melting start temperature is suppressed, and the low-temperature fixability can be satisfied. Therefore, by adopting a production method that controls the molecular weight distribution to a range that simultaneously satisfies the low-temperature fixing property and the offset resistance, the conventionally used toner using a styrene-based or polyester-based resin cannot be achieved. Low-temperature fixing can be obtained. Therefore, when the present invention is applied to a copying machine, a printer, or the like, power consumption can be reduced, which is extremely effective in reducing mechanical costs by reducing the pressure of a roll, and increasing the copying speed.

Claims (6)

[Claims] 1. A diol component which is a polyoxypropylene-modified bisphenol A, at least one dicarboxylic acid component selected from aromatic dicarboxylic acids, aliphatic dicarboxylic acids and alicyclic dicarboxylic acids, and a trivalent or higher polycarboxylic acid component. And at least one of a trihydric alcohol component and a trihydric or higher polycarboxylic acid component, wherein the total component ratio of the trihydric or higher polyhydric alcohol component and the trihydric or higher polycarboxylic acid component is equal to the total monomer content. 2.5 mol% or more and 10 mol% of the components
And the functional group ratio of all components is COOH / OH =
0.7-0.95 or OH / COOH = 0.7-0.
95 and a tetrahydrofuran (THF) -insoluble content of 5
Wt% or less, and the maximum value of the molecular weight (M
p) is 1 × 10 ³ or more and 6 × 10 ³ or less, and the relationship between Mp and the number average molecular weight (Mn) is Mp / Mn = 1.0 to 3.0.
0. A polyester resin for a toner, which is 0. 2. An acid value of 5 mg KOH / g or less, and a hydroxyl value of 60 mg KOH / g or less or an acid value of 60 mg KOH / g or less.
mgKOH / g or less and a hydroxyl value of 5 mgKO
The polyester resin for a toner according to claim 1, wherein the H / g is not more than H / g. 3. A polyoxypropylene-modified bisphenol A is reacted with at least one dicarboxylic acid selected from aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids, and Mp is 1 × 10 ³ or more. × 10 ³ or less, and the total of the acid value and the hydroxyl value is 100 mgKOH /
g or less of a linear polyester is synthesized, and at least one of a trihydric or higher polyhydric alcohol and a trihydric or higher carboxylic acid is mixed with the linear polyester to cause a polycondensation reaction. Of the polyhydric alcohol and the polyhydric carboxylic acid having a valence of 3 or more are added in an amount of 2.5 mol%
The reaction is terminated when the torque at the time of addition of the monomer added later is set to 1 and the torque at the time of addition of 2 to 5 times the torque is set to 1 or more. Production method of polyester resin for toner. 4. An electrophotographic toner comprising the polyester resin for a toner according to claim 1. 5. The toner for electrophotography according to claim 4, wherein the melting start temperature is 60 ° C. or more and 105 ° C. or less. 6. The electrophotographic toner according to claim 4, wherein the difference between the softening point and the melting start temperature is from 15 ° C. to 45 ° C.