JP2007293123A - Method for producing polyester resin for toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polyester resin for toners, by which changes in resin physical properties with the passage of time are suppressed, and a polyester resin for toners having uniform resin physical properties is produced, even if a mixer or the like is not used. <P>SOLUTION: In the method for producing a polyester resin for toners by making a di- or higher valent acid component react with a di- or higher alcohol component, a reaction product is discharged from a polymerization tank, while forcedly cooling the resin in the polymerization tank at a cooling rate of 1-100°C/h or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polyester resin for toner.

  In the production process of the polyester resin, after the polymerization reaction is performed, the inside of the polymerization vessel is pressurized with an inert gas, the polyester resin is discharged, cooled and solidified by a cooling device, and then pulverized by a pulverizer. ing.

  Among these, when the polyester resin is discharged from the polymerization kettle, the resin properties such as viscosity and melt elasticity of the discharged polyester resin change depending on the difference in the residence time of the polyester resin in the polymerization kettle corresponding to the discharge time. The resulting polyester resin is known to be a mixture of different resin physical properties corresponding to the discharge time. In such a mixture of polyester resins having different resin physical properties, since the uniformity of the resin physical properties is low, when this is used as a binder resin for toner, poor fixing of toner to paper or photoreceptor contamination occurs. There was a problem such as.

  In order to improve the non-uniformity of the resin physical properties corresponding to the change with time of discharge, Patent Document 1 sets the resin discharge temperature lower than the reaction temperature, and the resin viscosity at the start of discharge and the resin viscosity at the end of discharge. A method has been proposed in which the difference between them is in a specific range. However, in the method described in Patent Document 1, since the time-dependent change in resin physical properties such as resin viscosity and melt elasticity during discharge of the resulting polyester resin from the kettle is large, in order to obtain sufficient resin physical properties, The discharged resin pulverized product needs to be mixed by a mixer, and there is a problem that a more complicated process is required.

JP 2005-157074 A

  An object of the present invention is to forcibly cool a resin in a polymerization kettle under specific cooling conditions to suppress a change in resin physical properties with time, and to have a uniform resin physical property without using a mixer or the like. It is providing the manufacturing method of the polyester resin for water.

  The present invention is a method for producing a polyester resin by reacting a divalent or higher acid component with a divalent or higher alcohol component, while forcibly cooling the resin in the polymerization kettle at a cooling rate of 1 to 100 ° C. or lower, The present invention relates to a method for producing a polyester resin for toner, wherein a reaction product is discharged from a polymerization kettle.

  The present invention also relates to a method for producing a polyester resin for toner, wherein the reactants in the polymerization vessel are discharged while being mixed.

  By using the method for producing a polyester resin for a toner according to the present invention, a method for producing a polyester resin for a toner having uniform resin physical properties can be provided without suppressing a change in the physical properties of the resin over time. it can.

The forced cooling in the present invention is a cooling method in which a heating source is shut off and cooling is performed using an active method, not natural cooling by standing to cool. The lower limit of the cooling rate when the resin in the polymerization kettle of the present invention is forcibly cooled is 1 ° C./h or more. When forced cooling is performed at 1 ° C./h or more, changes in resin physical properties such as resin viscosity and melt elasticity of the reactant discharged from the polymerization kettle with respect to discharge time can be suppressed, and the lower limit of this cooling rate is 3 ° C. / h or higher is more preferable, 6 ° C./h or higher is further preferable, and 9 ° C./h or higher is particularly preferable.
Moreover, as an upper limit of a cooling rate, it is 100 degrees C / h or less. When forced cooling is performed at 100 ° C./h or less, a change in the melt viscosity of the reactant during discharge can be suppressed, and stable discharge can be performed. The upper limit of the cooling rate of this forced cooling is more preferably 90 ° C./h or less, further preferably 70 ° C./h or less, and particularly preferably 50 ° C./h or less.

  As a method of discharging while forcibly cooling the resin in the polymerization kettle, a method of forcibly cooling the heat medium with a heat exchanger, a method of forcibly cooling the heat medium as a heating source and forcibly cooling with air, or removing the heat medium A method of replacing with a pre-cooled medium, a method of continuously charging a normal temperature or cooled metal block into the polymerization kettle, a method of continuously charging a normal temperature or cooled resin into the polymerization kettle, a continuous water or other refrigerant In order to simplify the industrial equipment and ease the control of the cooling rate, the heat medium is forcibly cooled by a heat exchanger. A method of discharging is preferable. When this forced cooling method is used, workability is good, and when the reactant is discharged from the polymerization kettle, the thickening of the resin in the polymerization kettle and the change in the physical properties of the resin over time can be more effectively suppressed. it can. Furthermore, the resin temperature during discharge is preferably higher by 30 ° C. than the softening temperature. By maintaining this temperature, it is possible to discharge without blocking when discharging.

  In addition, as a method of discharging while mixing the reactants in the polymerization kettle, there are methods such as stirring with a stirring blade and manual mixing using a spatula. And a method of discharging while mixing the reactants is preferable. When this mixing method is used, workability is good, the resin temperature in the pot is not uneven, and the resin temperature can be made uniform.

  As the shape of the stirring blade, there are cross type, paddle type, disk turbine type, double helical type, max blend, anchor type, fowler type, full zone type, ribbon type, etc. Max blend is preferable from the viewpoint of an increase in resin viscosity due to the condensation polymerization reaction.

  Constituent components of the polyester resin for toner produced by the production method of the present invention include a divalent or higher acid component and a divalent or higher alcohol component as basic constituent components.

  The divalent or higher acid component includes aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, aliphatic dicarboxylic acids such as phthalic acid, sebacic acid, isodecyl succinic acid, maleic acid, fumaric acid and adipic acid, and lower Examples thereof include alkyl esters and acid anhydrides. Examples of the lower alkyl ester of these dicarboxylic acids include monomethyl ester, monoethyl ester, dimethyl ester, diethyl ester and the like. Trivalent or higher polyvalent carboxylic acids can also be used. Examples of these polyvalent carboxylic acids include trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, and 2,5,7-naphthalenetricarboxylic acid. 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,2,7,8-octanetetracarboxylic acid and acid anhydrides thereof.

  Examples of the dihydric or higher alcohol component include ethylene glycol, neopentyl glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, and triethylene. Diols such as glycol, polyethylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A, polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxy Propylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.2) -polyoxyethylene- (2.0) -2,2-bis (4-hydroxy) Phenyl) propane, polyoxypropylene (6) -2,2-bis (4- Droxyphenyl) propane, polyoxypropylene- (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.4) -2,2-bis (4-hydroxyphenyl) Mention may be made of divalent alcohols such as bisphenol A alkylene oxide adducts such as propane and polyoxypropylene- (3.3) -2,2-bis (4-hydroxyphenyl) propane. Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexatetralol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4- Examples include butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4butanetriol, trimethylolpropane, 1,3,5-trihydroxymethylbenzene. Can do. These acid components and alcohol components may be used alone or in combination of two or more.

  Next, the polymerization reaction will be described. A divalent or higher acid component and a divalent or higher alcohol component, and if desired, in addition to these, a trivalent or higher polyvalent carboxylic acid and / or a trivalent or higher polyhydric alcohol component are added to the reaction vessel, and the temperature is increased. Then, esterification reaction or transesterification reaction is performed. The temperature of the esterification reaction or transesterification reaction is preferably 150 to 300 ° C. When the temperature of the esterification reaction or transesterification reaction is 150 ° C. or higher, the reaction rate tends to be sufficiently increased, and when it is 300 ° C. or lower, the decomposition reaction tends to be suppressed. The lower limit of the reaction temperature is more preferably 180 ° C. or higher, further preferably 200 ° C. or higher, particularly preferably 220 ° C. or higher, and most preferably 240 ° C. or higher. The upper limit is more preferably 290 ° C. or less, and particularly preferably 280 ° C. or less.

Next, water or alcohol generated in the reaction is removed according to a conventional method. Subsequently, the polymerization reaction is carried out. At this time, the condensation polymerization is carried out while distilling off the diol component under a vacuum of 150 mmHg (20 kPa) or less. The temperature of the condensation polymerization reaction is preferably 150 to 300 ° C. When the temperature of the condensation polymerization reaction is 150 ° C. or higher, the reaction rate tends to be sufficiently increased, and when it is 300 ° C. or lower, the decomposition reaction tends to be suppressed. The lower limit of the reaction temperature is more preferably 180 ° C. or higher, further preferably 200 ° C. or higher, and particularly preferably 220 ° C. or higher. The upper limit is more preferably 290 ° C. or less, further preferably 280 ° C. or less, and particularly preferably 260 ° C. or less.
The degree of vacuum is more preferably 100 mmHg (13.3 kPa) or less, and particularly preferably 50 mmHg (6.7 kPa) or less.

  In addition, as a catalyst used for esterification reaction, transesterification reaction, and condensation polymerization, a known catalyst such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide, or the like is used. be able to.

  In the case of producing a polyester resin having a cross-linked structure, a gelation reaction occurs and the viscosity in the reaction system rapidly increases in the process of proceeding the condensation polymerization while distilling and removing the aliphatic diol component under high vacuum. Therefore, it is preferable to control the gelation reaction by adjusting the degree of vacuum in the reaction system while responding to this increase in viscosity. When the desired viscosity is reached, the pressure in the reaction system is returned to normal pressure. It is preferable to discharge the resin from the polymerization kettle by applying pressure with nitrogen while forced cooling and stirring.

  Although there are various scales for the polymerization kettle, a scale of 10 t / kettle or less is preferable from the viewpoint of discharge time, polymerization kettle cooling speed, stirring speed of stirring blades, and the like.

  Further, the polyester resin for a toner in which the production method of the present invention exhibits the most effect is a trivalent or higher polyvalent carboxylic acid and / or a trivalent or higher polyhydric alcohol component in an amount of 5 to 50 mol, divalent or higher. The alcohol component is 120 to 140 mol, the softening temperature range is 130 to 150 ° C, the condensation polymerization reaction temperature is 220 to 240 ° C, and the discharge start temperature is 220 to 240 ° C.

  Hereinafter, the present invention will be described specifically by way of examples. In addition, the performance evaluation in the Example and the comparative example was performed using the following method.

・ Resin evaluation method (1) Softening temperature (℃)
When using a flow tester CFT-500 manufactured by Shimadzu Corporation with a 1 mmφ × 10 mm nozzle, a load of 294 N (30 kgf), and a constant temperature increase rate of 3 ° C./min, a sample of 1.0 g The temperature at which 1/2 flowed out was defined as the softening temperature.

(2) Change with time Resin was sampled every hour from the start to the end of discharge, the softening temperature was measured, and judged according to the following criteria.
○ (Good): Difference in softening temperature is less than 2 ° C Δ (Possible): Difference in softening temperature is 2 ° C or more and less than 4 ° C

(3) Toner Evaluation 93 parts by weight of polyester resin, 3 parts by weight of quinacridone pigment (E02 manufactured by Clariant), 3 parts by weight of carnauba wax (manufactured by Toyo Petroride), negative charge control agent (E-, manufactured by Orient Chemical Co., Ltd.) 84) One part by mass was mixed with a Henschel mixer for 30 minutes. Subsequently, the obtained mixture was melt-kneaded with a twin-screw kneader at a temperature in the range of 150 ° C to 200 ° C. After kneading, the mixture was cooled to obtain a toner lump, finely pulverized with a jet mill fine pulverizer, and the particle size of the toner was adjusted with a classifier to make the particle size 5 μm. To 100 parts by mass of the fine powder obtained, 0.25 part by mass of silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added, mixed and adhered with a Henschel mixer, and finally a toner was obtained. A solid image of 4.5 cm × 15 cm was printed with this toner at a toner concentration of 0.5 mg / cm ² . This solid image paper was fixed with a printer (SPEDIA N4-614, manufactured by Casio Computer Co., Ltd.) having a fixing roller not coated with silicone oil, a roller speed of 100 mm / second, and a temperature of 170 ° C. Judged by criteria.
○ (Good): Neither hot offset (HOS) nor cold offset (COS) occurs × (Inferior): Hot offset (HOS) and / or cold offset (COS) occurs

Example 1
In a polymerization kettle with a volume of 4 m ³ equipped with a Max blend stirring blade, distillation tower, temperature detection end in the kettle, thermometer, nitrogen gas introduction pipe, condenser, vacuum device, vacuum gauge, torque meter, discharge port, heat exchanger, With the charging composition shown in Table 1, 2000 kg of monomer components were charged. Further, 1000 ppm of antimony trioxide was added as a polymerization catalyst. Next, the number of revolutions of the stirring blade in the polymerization kettle was kept at 120 rpm, the temperature was raised by the heat medium jacket, and the temperature in the reaction system was heated to 265 ° C., and this temperature was maintained. Water was distilled from the reaction system, and about 7 hours after the start of the esterification reaction, the water was not distilled and the reaction was completed.

Next, the temperature in the reaction system was lowered to 230 ° C., the pressure in the polymerization vessel was reduced to 1 kPa over about 1 hour, and a condensation polymerization reaction was carried out while distilling the diol component from the reaction system. About 2 hours after the start of decompression, the viscosity of the reaction system increased with the reaction, so the degree of vacuum was lowered to 10 kPa and the reaction was continued. After 4 hours from the start of decompression, the reaction system was returned to normal pressure.
Next, the flow rate of circulating water in the heat exchanger was set to 6 m ³ / h, the circulating water temperature on the outlet side was set to 20 ° C., and forced cooling of the heat medium was started. Stirring was carried out at a rotation speed of 6 rpm and the pressure was applied with nitrogen at a discharge speed of 400 kg / h, and discharge of the resin in the kettle was started from the discharge port. While discharging, the resin was sandwiched between cooling belts and pulverized with a pink lasher. The temperature of the resin in the kettle was measured every hour from the start of discharge, the pulverized resin was sampled, and the softening temperature of the resin during each discharge was measured, and toner evaluation using this resin was performed. The results are shown in Table 1.

Example 2
A polyester resin was produced in the same manner as in Example 1 except that the charge composition of trimellitic anhydride used for the production of the polyester resin was changed to 18 mol. The results are shown in Table 1.

Example 3
A polyester resin was produced in the same manner as in Example 1 except that the charge composition of trimellitic anhydride used for the production of the polyester resin was changed to 25 mol. The results are shown in Table 1.

Example 4
A polyester resin was produced in the same manner as in Example 1 except that the flow rate of circulating water in the heat exchanger used for forced cooling was changed to 4 m ³ / h. The results are shown in Table 2.
Example 5
A polyester resin was produced in the same manner as in Example 1 except that stirring was not performed during discharge. The results are shown in Table 2.
Example 6
A polyester resin was produced in the same manner as in Example 1 except that the opening of the discharge valve was reduced and the discharge speed was 286 kg / h. The results are shown in Table 2.

Comparative Example 1
Polyester was produced in the same manner as in Example 1 except that forced cooling was not performed and the heating source was shut off and cooling was performed by natural cooling by standing to cool. The results are shown in Table 3.

Comparative Example 2
A polyester resin was produced in the same manner as in Comparative Example 1 except that the condensation polymerization reaction temperature was changed to 250 ° C. The results are shown in Table 3.

Comparative Example 3
The polyester resin is the same as in Example 1 except that the flow rate of circulating water in the heat exchanger used for forced cooling is changed to 100 m ³ / h so that the cooling rate of the resin temperature in the kettle is 150 ° C./h. Manufactured.
The discharge port was clogged when the temperature inside the pot was around 170 ° C, and it was possible up to 24 minutes from the start of discharge, but after 24 minutes (the temperature inside the pot was less than 170 ° C), it could not be discharged, Resin remained.

The following was found from the examples and comparative examples.
1) The polyester resins produced by discharging the reactants from the polymerization kettle while forcedly cooling in Examples 1 to 6 each have a small change in the softening temperature of the resin with respect to discharge time, and include the obtained polyester resins. The toner showed good fixing properties.
2) In Example 1 in which the cooling rate was set to 10 ° C./h by forced cooling, the change in the softening temperature with respect to discharge time was particularly small.
3) The polyester resin produced in Example 1 in which stirring was performed during discharge had a smaller change in the softening temperature of the resin particularly with respect to discharge time than the polyester resin in Example 5 in which stirring was not performed.

4) In Examples 1 and 2 in which the charge composition of trimellitic anhydride, which is a crosslinkable component, was 12 mol% and 18 mol%, the change in the softening temperature of the resin particularly with respect to discharge time was small.
5) In Example 6, the discharge port was clogged from around 168 ° C. in the pot, and it was possible up to 6 hours from the start of discharge, but after 6 hours (less than 168 ° C. resin temperature in the pot) Discharge was not possible and resin remained in the pot.

6) During the discharge, the polyester resin obtained in Comparative Example 1 having a cooling rate of 0.5 ° C./h has a large change in the softening temperature of the resin with respect to discharge time, and is discharged particularly after 3 hours from the start of discharge. The recovered resin has a low industrial utility value because a cold offset occurs in a fixing test using a toner containing the resin and a fixing characteristic required as a binder resin for a toner cannot be obtained.

7) The polyester resin obtained in Comparative Example 2 in which the condensation polymerization reaction temperature is 250 ° C. and the cooling rate of the resin temperature in the kettle is 0.5 ° C./h has a large change in the softening temperature of the resin with the passage of time. In particular, the resin discharged and recovered after 2 hours from the start of discharge is industrially used because a hot offset occurs in a fixing test using a toner containing the resin, and fixing characteristics required as a binder resin for toner cannot be obtained. The utility value was low.
8) In Comparative Example 3 in which the cooling rate of the resin temperature in the kettle is 150 ° C./h, the discharge port is clogged during discharge and stable discharge cannot be performed. Is low.

Claims (2)

  In the method for producing a polyester resin by reacting a divalent or higher acid component and a divalent or higher alcohol component, while the resin in the polymerization vessel is forcibly cooled at a cooling rate of 1 to 100 ° C./h or lower, A method for producing a polyester resin for toner, wherein the polyester resin is discharged from a polymerization kettle.   2. The method for producing a polyester resin for toner according to claim 1, wherein the reactants in the polymerization vessel are discharged while being mixed.