JPH1069126A - Polyester resin for toner, its production and electrophotographic toner using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner which can be fixed at low fixing temp., which causes no problem about offset in practical use which has excellent fixing strength to a transfer paper. SOLUTION: This polyester resin has <=5wt.% THF insoluble component. In the distribution of molecules in a THF-soluble component, the proportion of a ultrahigh mol.wt. as >=1×10<6> is between >=1wt.% and >=10wt.% and the proportion of high mol.wt. as >=1×10<5> is between >=10wt.% and <=20wt.%. The proportion W1 of a low mol.wt. molecule as <1×10<4> and the proportion W2 of a medium mol.wt. as between >=1×10<4> and <1×10<5> are in the relation of W1 >W2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly, to an electrophotographic toner for a copying machine or a printer which employs heat roll fixing.

[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 border 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. Yes,
In addition, as copiers have become more sophisticated, since copiers equipped with a two-sided copy function and an automatic document feeder have become widespread, the fixing temperature of electrophotographic toner used in copiers and printers is low, and the There is a demand for an electrophotographic toner that has excellent offset properties and has excellent fixing strength to transfer paper in order to prevent the occurrence of stains during duplex copying and the occurrence of stains in an automatic document feeder.

[0003] In response to the above demands, in the prior art, there have been proposed, for example, ones in which the molecular weight and molecular weight distribution of the binder resin are improved as follows. Specifically, attempts have been made to lower the fixing temperature by lowering the molecular weight of the binder resin. However, in the case of styrene acrylic resins that have been widely used, the lowering of the molecular weight makes the toner itself brittle, and the toner is pulverized by stress in a developing machine, causing a change in particle size distribution, a carrier or a developing sleeve. In long-term copying due to fusing, image quality deterioration due to changes in charging characteristics is inevitable. In addition, stains occurred during duplex copying and stains occurred in the automatic document feeder. On the other hand, in the case of the polyester resin, the lowering of the molecular weight lowers the melting point, but also lowers the viscosity at the same time, so that the offset phenomenon to the fixing roll occurs. In order to prevent this offset phenomenon, a cross-linking structure has been introduced to broaden the molecular weight distribution of the polyester resin. However, in this method, although the molecular weight distribution is broadened by cross-linking and a decrease in offset can be prevented, there is a problem that the overall molecular weight increases and the low-temperature fixability deteriorates. Therefore, in order to have sufficient fixability, the glass transition temperature (Tg) of the resin has to be lowered, and it is inevitable that the storage stability of the toner is impaired. As described above, the conventional technology could not achieve low-temperature fixability while satisfying offset resistance and storage stability.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic apparatus which can fix at a low fixing temperature, does not cause any practical problem in offset properties, and has excellent fixing strength to transfer paper. Another object of the present invention is to provide a toner polyester resin for obtaining such a toner and a method for producing the same.

[0005]

According to the present invention, the THF-insoluble content is 5% by weight or less, and the ratio of the ultra-high molecular weight substance having a THF-soluble content of 1 × 10 ⁶ or more is 1% by weight or more. 1% by weight or less, and the ratio of the high molecular weight substance of 1 × 10 ⁵ or more is 10% by weight or more and 20% by weight or less, and 1 × 1
0, wherein the ratio of the low molecular weight of less than ⁴ in the region having a W _{1, 1} × 10 ⁴ or more 1 × 10 W ₁ the ratio of the molecular weight material in less than ⁵ when the W _2> W ₂ becomes distribution And a method for producing the same, and an electrophotographic toner containing the same.

Hereinafter, the present invention will be described in detail. The polyester resin for a toner of the present invention is a branched polyester resin obtained by mixing at least one selected from a trivalent or higher polyvalent carboxylic acid component and a trivalent or higher polyhydric alcohol component as a crosslinking agent. It is a resin synthesized so as not to generate a gel component (= solvent-insoluble component) by crosslinking as much as possible. That is, it is characterized by being prepared so that the insoluble content of tetrahydrofuran (hereinafter referred to as THF) as a solvent is 5% by weight or less. If the THF-insoluble content is more than 5% by weight, the melt viscosity of the toner is too high when the toner is used, and the fixing strength at low temperatures is deteriorated. It is most preferable that there is no THF-insoluble content, that is, 0% by weight, in order to improve the low-temperature fixability. The THF-insoluble content was obtained by charging 0.5 g of resin in 50 ml of THF, heating and dissolving at 60 ° C. for 3 hours, filtering the insoluble resin content through a glass filter lined with a filter (Celite # 545), and drying at 80 ° C. with a vacuum dryer. Dry with. Assuming that the weight of the dried resin is Wd (g), the insoluble content (% by weight) = Wd / 0.5 × 100.

TH of the polyester resin for toner of the present invention
As for the molecular weight of the F-soluble component, the ratio of ultrahigh molecular weight substances of 1 × 10 ⁶ or more is 1% by weight or more and 10% by weight or less in a chromatogram measured by gel permeation chromatography (hereinafter, referred to as GPC). . If the content is less than 1% by weight, high-temperature offset occurs in the case of hot roll fixing, and
If the content exceeds 0% by weight, the melt viscosity of the toner becomes too high, and the fixing strength at low temperatures deteriorates. Further, the proportion of the high-molecular-weight polymer of 1 × 10 ⁵ or more is 10% by weight or more and 20% by weight or less, and if it is less than 10% by weight, high-temperature offset also occurs. Too high, and the fixing strength at low temperatures deteriorates. Furthermore, 1 × 10
^When the ratio of low molecular weight substances in the region of less than ⁴ is W ₁ , and the ratio of medium molecular weight substances of 1 × 10 ⁴ or more and less than 1 × 10 ⁵ is W ₂ , W
_1> W has _two become distribution. When the ratio of the low molecular weight compound W ₁ is equal to or smaller than that of the medium molecular weight compound W ₂ , that is, W ₁ ≦ W
_When it is ₂ , the melting start temperature becomes high, and the fixability at a low temperature deteriorates. Also, the higher the ratio of low molecular weight compounds, the better the low-temperature fixability, but if the amount of medium molecular weight compounds is extremely low, the strength of the resin will be weak, and if it is used as toner, it will be pulverized in the developing machine, and the amount of ultrafine powder toner will increase. or lifetime of the developer is shortened by the developing sleeve, the toner fusion to a photosensitive member, since shortening the lifetime of the developing device W ₁
It is preferable that / W ₂ = 1.3 to 3.5.
If W ₁ / W ₂ is less than 1.3, it is difficult to obtain a sufficient fixing strength at a low temperature, and if it is more than 3.5, the hot offset becomes poor and the life of the developer tends to be short, which is not preferable. In order to further improve low-temperature fixability, W ₁ /
Most preferably, W ₂ = 1.9 to 3.5. In the present invention, the molecular weight distribution of the resin for toner is as follows:
50 ml of the THF solution in which the resin obtained at the time of extracting the THF-insoluble component is dissolved may be used as it is for the measurement, and is a value measured by GPC under the following conditions. The ratio of each molecular weight is obtained by analyzing the result of a chromatogram obtained by GPC and calculating from the integrated value in the range of each molecular weight. The GPC is measured by flowing a solvent (tetrahydrofuran) at a flow rate of 1 ml per minute at a temperature of 25 ° C. and injecting 8 mg of a tetrahydrofuran sample solution having a concentration of 0.4 gr / dl as a sample weight to 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 by NBS7 under the above measurement conditions.
06 polystyrene standard sample (Mw = 28.8 × 10 ⁴ ,
M of Mn = 13.7 × 10 ⁴ , Mw / Mn = 2.11)
It can be confirmed that w / Mn is 2.11 ± 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 maximum value of the molecular weight in a region of 1 × 10 ³ or more and 1 × 10 ⁴ or less, and the total of the acid value and the hydroxyl value is 100.
After heating and melting a linear polyester resin having a KOH mg / g or less, at least one selected from a trivalent or more polyvalent carboxylic acid component and a trivalent or more polyhydric alcohol component, and a diol component and a dicarboxylic acid component are selected. And a polycondensation reaction with one or more of the above compounds to synthesize a polyester resin.

Specifically, first, a monomer having a diol component and a dicarboxylic acid component is used to perform a first-stage polycondensation reaction so as to have a maximum molecular weight of 1 × 10 ³ or more and 1 × 10 ⁴ or less. A linear polyester resin is synthesized so as to obtain a value, and once cooled at room temperature. In this case, when the maximum value of the molecular weight of the linear polyester resin is less than 1 × 10 ³ , the glass transition temperature decreases, and the glass transition temperature after the synthesis of the crosslinked resin also decreases, resulting in poor storage stability. on the other hand,
When the amount exceeds 1 × 10 ⁴ , the molecular weight after the synthesis of the crosslinked resin becomes too high, and the ratio of the ultrahigh molecular weight substance of 1 × 10 ⁶ or more in the THF soluble component of the toner resin is 1%.
There is a high possibility that the ratio exceeds 0% by weight, the proportion of the high molecular weight compound of 1 × 10 ⁵ or more exceeds 20% by weight, or the relationship of W ₁ > W ₂ cannot be satisfied. Is higher than 105 ° C., the toner is not sufficiently melted by the fixing roll, and the low-temperature fixability is deteriorated. The total of the acid value and the hydroxyl value of the linear polyester resin is 100 KOH.
mg / g or less. If the total of the acid value and the hydroxyl value, that is, the number of functional groups of the linear polyester resin is large and exceeds 100 KOHmg / g, the overall molecular weight of the polyester resin for a toner of the present invention obtained in the subsequent step increases, and the THF-insoluble When a large amount is generated, the melt viscosity increases and the low-temperature fixability deteriorates. Accordingly, in order to keep the molecular weight of the polyester resin for a toner of the present invention low and to lower the melting start temperature of the toner to maintain good low-temperature fixability, the total of the acid value and the hydroxyl value of the linear polyester resin is 100 KOHmg. / G or less, preferably 60 KOH mg / g or less. The measurement of the acid value and the hydroxyl value is carried out by the method shown in JIS K0070.

Examples of the diol component and dicarboxylic acid component used in the synthesis of the linear polyester resin include the following. The diol component includes polyoxypropylene bisphenol A, polyoxyethylenated bisphenol A, polyoxyethylenated biphenol, polyoxypropylene biphenol, diethanolamine, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, isopropylene glycol, and octanediol. , 2,2-diethyl-1.3-propanediol, spiro glycol, neopentyl glycol, 1.3-butanediol, 1,
4-butanediol, 2-butyl-2-ethyl 1,3-
Propanediol, 1,6-hexanediol, hexylene glycol, 1.5-pentanediol, 3-methyl-1,5-pentanediol, hydrobenzoin, bis (β-hydroxyethyl) terephthalate, bis (hydroxybutyl) terephthalate, etc. Is mentioned.

The dicarboxylic acid component includes fumaric acid, maleic acid, phthalic acid, isophthalic acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, dodecane diacid. Acid, 1,12-dodecanedicarboxylic acid, naphthalenedicarboxylic acid, biphenyl-4,4-
Dicarboxylic acid, 2,3-piperazine-dicarboxylic acid, iminodicarboxylic acid, imidazole-4,5-dicarboxylic acid, piperidinedicarboxylic 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, 4-hydroxyisophthalic acid, 2,5-hydroxy-1,4-benzenediacetic acid, kelidamic acid , Bis (2-hydroxy-3
-Carboxyphenyl) methane and the like, and their acid anhydrides and their lower alkyl esters can be used.

Next, in the polyester resin for toner of the present invention, 80 to 95 parts by weight of the linear polyester resin obtained in the first step is heated and melted again at a temperature of 180 ° C. to 230 ° C. Thereafter, a total of 5 to 20 parts by weight of at least one selected from a trivalent or higher polyhydric carboxylic acid component and at least one trivalent or higher polyhydric alcohol component and one selected from a diol component and a dicarboxylic acid component It can be obtained by mixing the above and further proceeding the second stage polycondensation reaction. By taking this two-stage polycondensation process, it is possible to form the polyester resin for a toner of the present invention, in which the increase in molecular weight is small even when a trivalent or higher polyvalent monomer is used, that is, the molecular weight is kept low. In this case, it is preferable that the monomers used for the second-stage polycondensation reaction are simultaneously added in a short time in order to keep the molecular weight distribution within a target region.

Examples of the trivalent or higher polyvalent carboxylic acid component and the trivalent or higher polyhydric alcohol component that can be used in the second stage polycondensation reaction include the following.
As the diol component and the dicarboxylic acid component, those exemplified for the linear polyester resin can be used as they are. That is, the trivalent or higher polycarboxylic acid component includes trimellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,5,7-naphthalenedicarboxylic acid, and pyridinetricarboxylic acid. Acids, pyridine-2,3,4,6-tetracarboxylic acid, 1,2,7,8-tetracarboxylic acid, butanetetracarboxylic acid and the like, and their acid anhydrides and lower alkyl esters thereof Can be used. Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol,
4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-
Butanetriol, 1,2,5-pentanetriol,
Glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane,
1,3,5-trihydroxybenzene and the like.

Next, the electrophotographic toner of the present invention will be described. In the electrophotographic toner of the present invention, in addition to the polyester resin for the toner, other resins, a colorant, a magnetic substance, and a property improving agent such as a charge controlling agent and a fluidizing agent can be used. In the method for producing an electrophotographic toner of the present invention, a resin, a colorant, a charge control agent, and the like are mixed in advance with a super mixer. Next, the mixed materials are melt-kneaded using a Banbury mixer, a roll mill, a kneader, an extruder, or the like. The kneaded material is roughly pulverized by a cutter mill, a hammer mill or the like, and then finely pulverized by a jet mill or the like. The classification is adjusted to a predetermined particle size distribution using an air classifier or the like. The toner after classification can be mixed with an external additive or the like for adjusting the fluidity to obtain the electrophotographic toner of the present invention.

As the binder resin of the toner for electrophotography 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, and a silicone resin A resin such as a resin, a polyamide resin, or a polyurethane resin may be blended.

The colorant used in the electrophotographic toner of the present invention includes carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow,
Examples include Ultramarine Blue, Dupont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, mixtures thereof, and others. These colorants need to be contained in a sufficient ratio to form a visible image having a sufficient concentration, and usually a ratio of about 1 to 20 parts by weight based on 100 parts by weight of the binder resin. Is done.

The magnetic material used in the toner for electrophotography of the present invention includes ferrite, magnetite and other ferromagnetic metals or alloys, such as iron, cobalt and nickel, compounds containing these elements, or ferromagnetic compounds. Alloys that do not contain elements but become ferromagnetic when subjected to an appropriate heat treatment, such as manganese-copper-aluminum, manganese-copper-tin, and other types of alloys called Heusler alloys containing manganese and copper, or Chromium dioxide and others can be mentioned. These magnetic materials are uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.1 to 1 micron. The content of the toner 100
It is 20 to 70 parts by weight, preferably 40 to 70 parts by weight per part by weight.

The toner for electrophotography according to 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 substance is contained, it may be used as it is as a one-component developer without mixing with a carrier for developing an electrostatic image, or may be mixed with a carrier and used as a two-component developer. Further, the present invention can be applied to a non-magnetic one-component developing method.

As for the melting characteristics of the electrophotographic toner, the melting start temperature is preferably from 60 ° C. to 105 ° C. in order to improve the fixability at a lower temperature. When the melting start temperature is lower than 60 ° C., the blocking property of the toner is deteriorated, and a problem may occur in the storability. On the other hand, when the temperature exceeds 105 ° C., the low-temperature fixability deteriorates, which is not preferable. In order to provide a sufficient fixing offset width, 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 preferably 15 ° C. or more and 45 ° C. or less. If the temperature is lower than 15 ° C., the fixing offset width (non-offset temperature width) becomes narrow,
Exceeding the above range is not preferable because the offset resistance can be maintained satisfactorily, but the low-temperature fixability deteriorates. In order to improve the low-temperature fixability, the melting start temperature is 60 ° C. or higher and 1
The temperature is most preferably not higher than 00 ° C.

The above-mentioned melting start temperature means the temperature at which the plunger starts to fall under the following measuring machine and measuring conditions. The softening point refers to the temperature at the middle point from the plunger descent start temperature to the descent end temperature. Measuring machine; High flow tester CF- manufactured by Shimadzu Corporation
Plunger: 1 cm ² Die diameter: 1 mm Die length: 1 mm Load: 20 KgF Preheating temperature: 50 to 80 ° C Preheating time: 300 sec Heating rate: 6 ° C / min

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
In the examples, parts are parts by weight. <Example 1> Polyoxyethylenated bisphenol A3
16 g (1 mol), 133 g (0.8 mol) of terephthalic acid and 0.005 g of dibutyltin oxide as a catalyst
Was placed in a four-necked round-bottomed flask equipped with a stirrer, a condenser and a nitrogen inlet, and heated and stirred at 200 ° C. while introducing nitrogen gas from the nitrogen inlet. Next, after the outflow of water was completed, the temperature was raised to 230 ° C. over about 1 hour, and the mixture was heated and stirred for 2 hours, taken out in a molten state, and once cooled at room temperature to obtain a linear polyester resin (I). . This linear polyester resin (I) has a Tg of 65 ° C. and a melting start temperature of 8 ° C.
7 ° C., softening point is 100 ° C., and the maximum value of the molecular weight is 6.1.
× 10 ³ , acid value 10KOHmg / g, hydroxyl value 50KO
Hmg / g. Next, 100 g of the linear polyester resin (I) was placed in a four-necked round bottom flask equipped with a stirrer, a condenser and a nitrogen inlet, and heated and stirred at 180 ° C. for 1 hour while introducing nitrogen gas from the nitrogen inlet. did. Then, 6.4 g of pentaerythritol and 1.1
6.0 g of 2-dodecanedicarboxylic acid and 0.3 g of dibutyltin oxide were added all at once, and the temperature was raised to 200 ° C. to about 1 g.
The reaction was stopped when the viscosity was increased by heating and stirring for 4 hours, and the torque was increased to four times the stirring torque immediately after the introduction of the monomer. Thus, a polyester resin A for toner of the present invention was obtained. <Example 2> Linear polyester resin (I) 1 of Example 1
00 g was placed in a four-necked round bottom flask equipped with a stirrer, a condenser and a nitrogen inlet, and heated and stirred at 180 ° C. for 1 hour while introducing nitrogen gas from the nitrogen inlet. Thereafter, 5.3 g of pentaerythritol, 5 g of 1,12-dodecanedicarboxylic acid, and 0.3 g of dibutyltin oxide were added all at once, and the temperature was raised to 200 ° C., and the mixture was heated and stirred for about 1 hour to increase the viscosity. The reaction was stopped when the torque increased to four times the immediately following stirring torque, and a polyester resin B for toner of the present invention was obtained.

Example 3 100 g of the linear polyester resin (I) of Example 1 was placed in a four-necked round-bottomed flask equipped with a stirrer, a condenser and a nitrogen inlet, and nitrogen gas was introduced from the nitrogen gas inlet. After heating and stirring at 180 ° C. for 1 hour, 4.2 g of pentaerythritol and 1,
4.0 g of 12-dodecanedicarboxylic acid and 0.3 g of dibutyltin oxide were charged all at once, heated to 200 ° C., and heated and stirred for about 1.5 hours to increase the viscosity. When the torque doubled, the reaction was stopped to obtain a polyester resin C for toner of the present invention. <Example 4> Linear polyester resin (I) 1 of Example 1
In a four-necked round-bottomed flask equipped with a stirrer, a condenser, and a nitrogen inlet, the mixture was heated and stirred at 180 ° C. for 1 hour while introducing nitrogen gas from the nitrogen inlet, followed by 3.7 g of pentaerythritol and 1 g of pentaerythritol. 3.5 g of 12,12-dodecanedicarboxylic acid, 0.3 g of dibutyltin oxide
At a time, the temperature was raised to 200 ° C., and the mixture was heated and stirred for about 2 hours to increase the viscosity.
When the torque doubled, the reaction was stopped, and a polyester resin D for toner of the present invention was obtained. <Example 5> Linear polyester resin (I) 1 of Example 1
00 g was placed in a four-necked round bottom flask equipped with a stirrer, a condenser and a nitrogen inlet, and heated and stirred at 180 ° C. for 1 hour while introducing nitrogen gas from the nitrogen inlet. Thereafter, 3.5 g of butanetetracarboxylic acid and polyethylene glycol (hydroxyl value 558 KOH mg / g, molecular weight 2
00) 10 g and 0.3 g of dibutyltin oxide were added all at once, heated to 200 ° C., heated and stirred for about 1 hour, the viscosity increased, and the torque increased to four times the stirring torque immediately after the introduction of the monomer. To stop the reaction, to obtain a polyester resin E for toner of the present invention.

<Comparative Example 1> 316 g (1 mol) of polyoxyethylenated bisphenol A, 133 g of terephthalic acid
(0.8 mol), butanetetracarboxylic acid 5.8 g, polyethylene glycol (hydroxyl value 558 KOHmg /
g, molecular weight 200), 10 g, and 0.5 g of dibutyltin oxide as a catalyst were placed in a four-necked round-bottom flask equipped with a stirrer, a condenser and a nitrogen inlet, and heated at 200 ° C. while introducing nitrogen gas from the nitrogen inlet. The mixture was heated and stirred. After the outflow of water was completed, the temperature was raised to 230 ° C. over about 1 hour, and the mixture was heated and stirred for 2 hours. When the viscosity increased and the resin was wound around the stirrer, the reaction was stopped, and the polyester resin F for comparison was removed. Obtained. <Comparative Example 2> Linear polyester resin (I) 1 of Example 1
00g was placed in a four-necked round bottom flask equipped with a stirrer, a condenser and a nitrogen introducing agent, and heated and stirred at 180 ° C. for 1 hour while introducing nitrogen gas from the nitrogen gas introducing agent.
Polyethylene glycol (hydroxyl value 558 KOHmg /
g, molecular weight 200) and stirred until uniform for about 1 hour. Then, butanetetracarboxylic acid 5.
8 g and 0.3 g of dibutyltin oxide were added, and 200 ° C.
And the mixture was heated and stirred for about 1 hour to increase the viscosity. When the resin was wound around the stirrer, the reaction was stopped to obtain a polyester resin G for comparison.

Comparative Example 3 100 g of the linear polyester resin (I) of Example 1 was placed in a four-necked round bottom flask equipped with a stirrer, a condenser and a nitrogen inlet, and nitrogen gas was introduced from the nitrogen inlet. After heating and stirring at 180 ° C. for 1 hour, 3.7 g of pentaerythritol and 1,
3.5 g of 12-dodecanedicarboxylic acid and 0.3 g of dibutyltin oxide were added all at once, heated to 200 ° C., and heated and stirred for about 2 hours to increase the viscosity to twice the stirring torque immediately after the introduction of the monomer. Stop the reaction when the torque rises,
A polyester resin H for comparison was obtained. Comparative Example 4 Only the linear polyester resin (I) of Example 1 was used.

Next, the molecular weights of the THF-insoluble component and the THF-soluble component of the polyester resin for toner and the polyester resin for comparison in the above Examples were measured under the above-mentioned measurement conditions.
The results are shown in Table 1. Next, the polyester resin for toner and the polyester resin for comparison of each of the above examples and other raw materials were mixed with a super mixer at the following mixing ratio, melt-kneaded, pulverized and classified to have an average particle diameter of 11 μm.
After obtaining m particles, 0.3 parts of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was adhered to the surface of the particles using a Henschel mixer to obtain a negatively chargeable electrophotographic toner. Further, characteristics of each of the above electrophotographic toners, such as Tg, were evaluated, and the results are shown in Table 1.

Next, the following fixing characteristics were tested for the above Examples and Comparative Examples. (1) Non-Offset Temperature Region and Non-Offset Temperature Width First, 4 parts of each of the electrophotographic toners obtained in the above Examples and Comparative Examples and a ferrite carrier without resin coating (trade name: FL-1020, manufactured by Powder Tech) And 96 parts) to prepare a two-component developer. Next, a commercially available copying machine (trade name: SF-9, manufactured by Sharp Corporation) is used by using the developer.
800), a plurality of belt-shaped unfixed images having a length of 2 cm and a width of 5 cm were prepared on A4 transfer paper. Next, a heat fixing roll having a surface layer formed of Teflon and a pressure fixing roll having a surface layer formed of silicone rubber are rotated in pairs, and the fixing device is rotated at a roll pressure of 1 kg / cm ² and a roll speed of 20 rolls.
The toner image on the transfer paper having the unfixed image was fixed at each surface temperature by adjusting the surface temperature of the heat fixing roll stepwise by adjusting the surface temperature to 0 mm / sec. At this time, observation was made as to whether or not the toner was contaminated in the blank portion, and a temperature region in which no contaminant was generated was defined as a non-offset temperature region. The difference between the maximum value and the minimum value in the non-offset temperature region was defined as the non-offset temperature width. (2) Fixing Strength The set temperature of the heat fixing roll was set to 130 ° C., and the toner image on the transfer paper having the unfixed image was fixed. Then, the formed fixed image was rubbed with a cotton pad, and the fixing strength was calculated according to the following equation, which was used as an index of low energy fixing property. The image density in the following equation was measured by a Macbeth reflection densitometer RD-914. Fixing strength (%) = Image density of fixed image after rubbing / Image density of fixed image before rubbing × 100 The results of each of the examples and comparative examples obtained by the above test are shown in Table 1. It was right.

[0027]

[Table 1]

As is clear from the results shown in Table 1, the electrophotographic toner containing the polyester resin for a toner of the present invention has a fixing temperature on the low temperature side of 110 ° C. or less in a non-offset temperature region, and a non-offset temperature. 100 width
° C or more, which is a practically sufficient range. Even when the temperature of the heat fixing roll is 130 ° C, the fixing strength is 81 ° C.
% Or more. On the other hand, the electrophotographic toners of Comparative Examples 1 and 2 had a lower fixing temperature of 120 ° C. or higher in the non-offset temperature region and were higher than those of the Examples, and had lower fixing strengths of 59% or lower. Met. The toner for electrophotography of Comparative Example 3 has a non-offset temperature width of 45 ° C., which is narrower than that of the Example, and the toner for electrophotography of Comparative Example 4 has no non-offset region at all.
At a fixing temperature of 0 ° C., low-temperature offset occurred, and no fixing was possible.

[0029]

The polyester resin for a toner according to the present invention comprises:
Since a low-molecular-weight polyester resin having a low melt viscosity is provided with a constant high-molecular-weight component having a low solvent-insoluble content, an offset phenomenon can be prevented when a toner is formed.
Further, since the low molecular weight compound is controlled within a certain range, an increase in the melting start temperature can be suppressed, and the low-temperature fixability can be satisfied. In addition, by controlling the medium molecular weight to a certain range, the strength of the toner layer after fixing is improved, so that the fixing strength is improved, and the occurrence of stains on the double-sided copy and the occurrence of stains in the automatic document feeder are prevented. be able to. Therefore, by adopting a production method in which the molecular weight distribution is controlled to a range that simultaneously satisfies the low-temperature fixability and the offset resistance, the low-temperature fixability that cannot be achieved with the conventionally used toner using a styrene or polyester resin has been achieved. Can be obtained. Therefore,
When the present invention is applied to a copying machine, a printer, or the like, power consumption can be reduced, and effects such as a reduction in machine cost due to a reduction in roll pressure and an increase in copying speed can be achieved.

Claims (8)

[Claims] 1. A THF-insoluble content is 5% by weight or less, and a ratio of an ultrahigh molecular weight substance having a molecular weight of 1 × 10 ⁶ or more in a THF-soluble portion is 1% by weight or more and 10% by weight or less,
1 × 10 ⁵ or more of high molecular weight is 10% by weight or more 2
0% by weight or less, and the ratio of low-molecular-weight substances in the region of less than 1 × 10 ⁴ is W ₁ , and the ratio of medium-molecular-weight substances of 1 × 10 ^{4 to} less than 1 × 10 ⁵ is W ₂ , where W ₁ > A polyester resin for toner having a distribution of W ₂ . _2. The relationship of W ₁ > W ₂ satisfies W ₁ / W ₂ = 1.3 or more.
2. The polyester resin for a toner according to claim 1, wherein the polyester resin is 3.5. 3. It has a maximum molecular weight in the range of 1 × 10 ³ or more and 1 × 10 ⁴ or less, and the total of the acid value and the hydroxyl value is 100K.
After heating and melting a linear polyester resin having an OH mg / g or less, one or more selected from a trivalent or more polyvalent carboxylic acid component and a trivalent or more polyhydric alcohol component, and a diol component and a dicarboxylic acid component are selected. And a polycondensation reaction by mixing with at least one of the above-mentioned components, and the THF-insoluble content is 5% by weight.
And the molecular weight of the THF-soluble component is 1 × 1
0 ratio of ⁶ or more ultra-high molecular weight is not more than 10% by weight 1% by weight or more, the ratio of 1 × 10 ⁵ or more high molecular weight body 1
The proportion of the low molecular weight compound in the range of 0 to 20% by weight and less than 1 × 10 ⁴ is represented by W ₁ , 1 × 10 ^{4 to} 1 × 10 ^4
A method for producing a polyester resin for a toner, comprising: synthesizing a polyester resin having a distribution of W ₁ > W ₂ , where W ₂ is a ratio of a medium molecular weight compound of less than ⁵ . 4. The relationship of W ₁ > W ₂ satisfies W ₁ / W ₂ = 1.3 or more.
4. The method for producing a polyester resin for a toner according to claim 3, wherein the ratio is 3.5. 5. The THF-insoluble content is 5% by weight or less, and the ratio of the ultra-high molecular weight substance having a molecular weight of 1 × 10 ⁶ or more in the THF-soluble portion is 1% by weight or more and 10% by weight or less,
1 × 10 ⁵ or more of high molecular weight is 10% by weight or more 2
0% by weight or less, and the ratio of low-molecular-weight substances in the region of less than 1 × 10 ⁴ is W ₁ , and the ratio of medium-molecular-weight substances of 1 × 10 ^{4 to} less than 1 × 10 ⁵ is W ₂ , where W ₁ > An electrophotographic toner comprising a polyester resin for a toner having a distribution of W ₂ . 6. The relation of W ₁ > W ₂ satisfies W ₁ / W ₂ = 1.3 or more.
6. The electrophotographic toner according to claim 5, wherein the toner is 3.5. 7. The toner for electrophotography according to claim 5, wherein the melting start temperature is 60 ° C. or more and 105 ° C. or less. 8. The electrophotographic toner according to claim 5, wherein the difference between the softening point and the melting start temperature is from 15 ° C. to 45 ° C.