JP2010006928A - Method for producing crosslinked polyester resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a homogeneous polyester resin with less variation in softening temperatures of the resins at the initial stage and the latter half stage of extraction. <P>SOLUTION: The process for producing a polyester resin comprises esterification reaction of a polyvalent carboxylic acid and a polyhydric alcohol including a trivalent or more carboxylic acid and a trihydric or more alcohol, followed by polycondensation while satisfying formula (1): -0.0027T+0.6849≤P≤-0.0027T+0.6909, wherein T is a polycondensation temperature (°C), P is mass% of a polycondensation catalyst per total charge. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a polyester resin suitable for a binder resin for toner used in electrophotography, electrostatic recording method, electrostatic printing method and the like.

  The polyester resin has excellent low-temperature fixability and is useful as a binder resin for toner. In addition, as the demand for higher image quality of toner increases, toner quality variation becomes an important factor, and polyester resin used as a binder resin also requires uniform physical properties.

  However, since the polyester resin is produced by a condensation polymerization reaction, in the conventional large-lot production method, after reaching the predetermined degree of polymerization, the polymerization reaction is not carried out in the reaction apparatus while the obtained resin is sequentially taken out. Therefore, the degree of polymerization is different between the resin at the beginning of extraction and the resin at the end of extraction, and the softening temperature is different, resulting in variations in the softening temperature.

For this reason, Patent Document 1 describes a method for producing polyester in which the reaction is stopped when a desired degree of polymerization is reached by controlling the condensation polymerization reaction rate by adjusting the pressure of the reaction system.
Japanese Unexamined Patent Publication No. 63-280729

  However, this method is not sufficient to prevent variations in the softening temperature between the resin at the beginning of removal and the resin at the end of removal. The present invention aims to solve these problems.

  The gist of the present invention is a polyester resin in which polyhydric carboxylic acid and trihydric alcohol containing trivalent or higher carboxylic acid or trivalent or higher alcohol are esterified and then subjected to polycondensation under the condition satisfying the formula (1). It is in the manufacturing method.

−0.0027T + 0.6849 ≦ P ≦ −0.0027T + 0.6909 (1)
(T: condensation polymerization temperature (° C.), P: mass% of condensation polymerization catalyst with respect to the total charged amount)

  According to the present invention, it is possible to obtain a uniform polyester resin having a small softening temperature variation between an initial resin and a resin in the latter half of the extraction.

  The method for producing a polyester resin according to the present invention comprises polycondensation under conditions satisfying the formula (1) after esterifying a polyvalent carboxylic acid and a polyhydric alcohol containing a trivalent or higher carboxylic acid or a trivalent or higher alcohol. To do.

−0.0027T + 0.6849 ≦ P ≦ −0.0027T + 0.6909 (1)
(T: condensation polymerization temperature (° C.), P: mass% of condensation polymerization catalyst with respect to the total charged amount)
The total amount charged refers to the total amount of polyvalent carboxylic acid, polyhydric alcohol, polycondensation catalyst, and additive charged at the start of the esterification reaction.

  The esterification reaction of a polyvalent carboxylic acid containing a trivalent or higher carboxylic acid or a trivalent or higher alcohol and a polyhydric alcohol may be carried out by a known method. For example, a polyvalent carboxylic acid and a polyhydric alcohol, a condensation polymerization catalyst may be used. , And an additive are charged in a reaction vessel, heated to a reaction temperature of 240 ° C. or higher under pressure, and the reaction is carried out until water distillation ceases while gradually returning the pressure to normal pressure.

  Next, after completion of the esterification reaction, the reaction system is decompressed, and a condensation polymerization reaction is carried out while distilling the diol component from the reaction system at a predetermined condensation polymerization temperature. As the viscosity of the reaction system increases, the degree of vacuum is increased and the condensation polymerization reaction is performed until the stirring blade torque reaches a value indicating the desired softening temperature. The polymerization reaction is terminated.

  In the present invention, it is necessary to satisfy the formula (1) when performing the condensation polymerization reaction.

−0.0027T + 0.6849 ≦ P ≦ −0.0027T + 0.6909 (1)
When the mass% (P) of the polycondensation catalyst with respect to the total amount charged is less than the appropriate value for a given polycondensation temperature, the polycondensation time is delayed and the time that is maintained at a high temperature becomes long, and the polyester resin is being taken out. In addition, the polyester resin undergoes thermal decomposition due to the latent heat in the reaction system, and as a result, the softening temperature varies when taken out.

  When P is larger than the appropriate value, the condensation polymerization catalyst itself is involved in the decomposition of the polyester, and the polyester resin is decomposed even during the removal of the polyester resin. As a result, the softening temperature varies during the removal.

  The condensation polymerization temperature (T) is preferably 210 ° C. or higher and 240 ° C. or lower. If the condensation polymerization temperature is less than 210 ° C, the reaction rate is remarkably reduced, and it is difficult to obtain a desired resin within an industrially appropriate time. If the temperature exceeds 240 ° C, thermal decomposition of the polyester resin occurs, and softening at the time of removal. Temperature variation is likely to occur.

  Furthermore, in the present invention, it is preferable to have a cooling step of cooling the obtained polyester resin to 40 ° C. or less within 2 hours after the completion of the condensation polymerization reaction.

  When the cooling time for cooling to 40 ° C. or lower exceeds 2 hours, the polyester resin causes thermal decomposition, and the softening temperature at the time of taking out tends to vary.

  After the condensation polymerization reaction, the cooling device for cooling the polyester includes steel belt cooler (manufactured by Nippon Belting Co., Ltd., Sandvik Co., Ltd.), drum cooler (manufactured by Ryoka Techno Co., Ltd., Mitsui Miike). (Chemical Machinery Co., Ltd.) and the like, and a steel belt cooler is preferable from the viewpoint of heat exchange capacity. In addition, from the viewpoint of further improving the cooling efficiency by the cooling device, a method of cooling while rolling is preferable.

  Further, in the present invention, by containing a trivalent or higher carboxylic acid or a trivalent or higher alcohol, a cross-linked structure within or between the polyester molecules is formed, and there is an effect of imparting toughness of the polyester resin. A polyester resin suitable for the resin is obtained.

  Examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1.2,4-cyclohexanedicarboxylic acid, 2,5,7 mononaphthalenetricarboxylic acid, 1 2,2,4-naphthalene tricarboxylic acid, 1,2,7,8-octanetetofu carboxylic acid and acid anhydrides thereof, and the like, in particular, 1,2,4-benzenetricarboxylic acid and acid anhydrides thereof (trimellitic anhydride). Acid) is preferred.

  Examples of the trihydric or higher alcohol include glycerin, pentaerythritol, trimethylolpropane, sorbitol and the like, and trimethylolpropane is particularly preferable.

  Examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, or lower alkyl esters thereof. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include dimethyl terephthalate, dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate, dibutyl terephthalate, and dibutyl isophthalate. In this respect, terephthalic acid and isophthalic acid are preferable. These dicarboxylic acids or lower alkyl esters thereof are used alone or in combination of two or more.

  Examples of other useful dicarboxylic acids include phthalic acid, sebacic acid, isodecyl succinic acid, dodecenyl succinic acid, maleic acid, fumaric acid, adipic acid, or their monomethyl, monoethyl, dimethyl, diethyl esters or their acid anhydrides. Things. These dicarboxylic acids are related to basic characteristics such as toner fixing properties and blocking resistance.

Examples of the polyhydric alcohol include polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.0) -2,2-bis (4 -Hydroxyphenyl) propane, polyoxypropylene (2.2) -polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.4) -2,2-bis (4-hydroxyphenyl) ) Aromatic diol components such as propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane, and the like. It may be used alone or in a mixture.
Since the aromatic diol component has the effect of increasing the glass transition temperature, the resulting toner has good blocking resistance. In particular, polyoxypropylene (n) -2,2-bis (4-hydroxyphenyl) propane in which the number n of polyoxypropylene or polyoxyethylene units is 2.1 ≦ n ≦ 8 and 2.0 ≦ n ≦ 3 Polyoxyethylene (n) -2,2-bis (4-hydroxyphenyl) propane which is 0.0 is preferred.

  Other useful polyhydric alcohols include ethylene glycol, butanediol, polyethylene glycol, 1,2-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, hydrogenated bisphenol A, and the like. These can be used alone or in a mixture.

  Furthermore, in the present invention, a polyalkylene alcohol or a polyalkylenecarboxylic acid compound may be included as an additive for improving the dispersibility of the wax when used as a binder resin for toner.

  The polycondensation catalyst for the polyester resin is not particularly limited. For example, titanium tetrabutoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium oxide, and the like can be used.

  Examples of the present invention are shown below. Moreover, the evaluation method of resin shown by a present Example is as follows.

(Variation in softening temperature of polyester resin)
Evaluation was made by the difference ΔT (° C.) between the maximum value and the minimum value of the softening temperature during resin removal. The resin is sampled every 10 minutes from the start to the end of taking out the resin, and the softening temperature is measured. Regarding the obtained softening temperature value, the difference between the maximum value and the minimum value is defined as ΔT (° C.). If ΔT is 10 or less, there is no problem in variation in softening temperature.

  The softening temperature was measured by the following method.

When using a flow tester CFT-500 manufactured by Shimadzu Corporation and measuring with a 1 mmφ × 10 mm nozzle under a constant temperature increase with a load of 294 N (30 Kgf) and a temperature increase rate of 3 ° C./min, The temperature at which 1/2 of the flowed out was defined as the softening temperature.

(Examples 1-4)
A 6 m ³ batch reactor equipped with a condenser, pressure control equipment, and a stirrer was charged with polycarboxylic acid and polyhydric alcohol having the composition shown in Table 1 and antimony trioxide as a polycondensation catalyst.

  Subsequently, the pressure in the reaction apparatus was maintained at 450 kPa and the rotation speed of the stirring blade was maintained at 130 rpm, the temperature increase was started, 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 150 minutes after the start of the esterification reaction, the pressure was reduced to 0 kPa over 15 minutes, and the pressure was further maintained for 10 minutes. finished.

  Subsequently, the condensation polymerization temperature shown in Table 1 was maintained, the pressure in the reaction vessel was reduced over about 30 minutes, the degree of vacuum was 15.0 mmHg, and the condensation polymerization reaction was performed while distilling the diol component from the reaction system.

  The viscosity of the reaction system increased with the reaction, the degree of vacuum was increased with the increase of the viscosity, and the condensation polymerization reaction was carried out until the torque of the stirring blade showed a value at which the softening temperature of the resin was 142 ° C.

  When the stirring blade torque showed a predetermined torque, the reaction system was returned to normal pressure, heating was stopped, and the polycondensation reaction was completed.

  Next, the take-out valve was opened, the melt was poured into a steel belt cooler (made by Nippon Belting Co., Ltd.), pressurized with nitrogen, and the polyester resin cooled to 36 ° C. was taken out at the take-out time shown in Table 1. .

  Further, the resin was sampled every 10 minutes from the start to the end of taking out the resin, and the difference ΔT (° C.) between the maximum value and the minimum value of the softening temperature was obtained.

(Comparative Examples 1-2)
A polyester resin was obtained in the same manner as in Example 2 except that the condensation polymerization temperature was changed to the values shown in Table 1.

Comparative Example 1 has a high polycondensation temperature, Comparative Example 2 has a low polycondensation temperature, and the polyester resins obtained without satisfying the formula (1) both have large variations in softening temperature. Met.

Claims (2)

A method for producing a polyester resin, comprising esterifying a polyvalent carboxylic acid and a polyhydric alcohol containing a trivalent or higher carboxylic acid or a trivalent or higher alcohol, and then subjecting the polycondensation to a condition satisfying the formula (1).
−0.0027T + 0.6849 ≦ P ≦ −0.0027T + 0.6909 (1)
(T: condensation polymerization temperature (° C.), P: mass% of condensation polymerization catalyst with respect to the total charge)   The method for producing a polyester resin according to claim 1, further comprising a cooling step of cooling the temperature of the obtained polyester resin to 40 ° C or lower within 2 hours after the completion of the condensation polymerization reaction.