JP2013166816A - Highly flowable polyester resin and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a polyester resin having high flowability while keeping its own mechanical strength properties such as tensile rupture-inducing distortion strength without impairing its own polycondensation reactivity and quality and being slight in fear of thickening (gelation).SOLUTION: A method for producing a polyester (resin) comprises: an esterification step of carrying out an esterification reaction and/or transesterification reaction between a dicarboxylic acid component comprising terephthalic acid or its ester-forming derivative and a diol comprising 1,4-butanediol, and a polycondensation step of carrying out a polycondensation reaction of the resultant oligomer obtained in the esterification step, wherein a fatty acid ester compound composed of the corresponding fatty acid and polyhydric alcohol and/or a polycarboxylic acid ester compound composed of the corresponding polycarboxylic acid and alcohol are incorporated into the reaction system.

Description

  The present invention relates to a method for producing polybutylene terephthalate having high fluidity during melt molding, among polyesters.

  Polybutylene terephthalate (hereinafter sometimes referred to as PBT) has excellent mechanical properties, heat resistance, moldability and recyclability, and has high mechanical strength and chemical resistance. It is widely used for films, fibers and the like, and in particular, it is widely used as a material for industrial molded products such as connectors, relays and switches for automobiles and electrical / electronic devices.

  PBT usually forms an oligomer which is a polyester precursor by direct esterification reaction between terephthalic acid and 1,4-butanediol (hereinafter sometimes referred to as 1,4-BG), and then the oligomer is subjected to atmospheric pressure or A method of producing by polycondensation reaction under reduced pressure, or an ester exchange reaction between an ester-forming derivative of terephthalic acid and 1,4-BG to form an oligomer which is a polyester precursor, and then the oligomer is subjected to atmospheric pressure or It is produced by a method of producing by polycondensation reaction under reduced pressure. At this time, it is well known that a titanium compound is used as a reaction catalyst.

On the other hand, in recent years, there has been an increasing demand for miniaturization and weight reduction of industrial molded products, and it is desired to improve the fluidity at the time of melt molding at the same time as further improving the mechanical strength. It has been desired to produce the product efficiently.
Conventionally, a method for efficiently producing a polyester resin having high fluidity by adding a compound having three or more functional groups in the course of producing the polyester resin has been proposed (see Patent Document 1). However, with the disclosed technology, good flowability PBT can be obtained, but there is a concern about increase in viscosity (gelation) due to the influence of the addition of a polyfunctional branching agent or strength properties such as tensile fracture nominal strain strength of polyester resin. There is a problem of being.

JP 2001-200038 A

  In view of the above problems, the problem of the present invention is that there is little concern about thickening (gelation) without impairing polycondensation reactivity and quality, and high fluidity while maintaining strength physical properties such as tensile fracture nominal strain strength. It is providing the method of manufacturing the polyester resin which has.

As a result of earnestly examining the above problems, the inventors of the present invention, in a method for producing a polyester resin, include a fatty acid ester compound and / or a polyvalent carboxylic acid and an alcohol having a fatty acid and a polyhydric alcohol as constituents in a reaction system. The inventors have found a production method in which a polyvalent carboxylic acid ester compound as a constituent component is added, and have reached the present invention.
That is, the gist of the present invention resides in the following [1] to [4].
[1] An esterification step in which an esterification reaction and / or a transesterification reaction between a dicarboxylic acid component having terephthalic acid or an ester-forming derivative thereof as a main component and a diol having 1,4 butanediol as a main component, and In a method for producing a polyester through a polycondensation step in which a polycondensation reaction is performed on an oligomer obtained by an esterification step, a fatty acid ester compound and / or a polyvalent carboxylic acid and an alcohol having a fatty acid and a polyhydric alcohol as constituent components in the reaction system A method for producing a polyester resin, comprising adding a polyvalent carboxylic acid ester compound containing as a constituent component.

[2] The polyester resin according to [1], wherein 0.2 to 10 parts by weight of the fatty acid ester compound and / or the polycarboxylic acid ester compound is added to the reaction system with respect to 100 parts by weight of the obtained polyester resin. Production method.
[3] In the esterification reaction, transesterification reaction, or polycondensation reaction, a reaction catalyst is used, and a titanium compound and a periodic table Group 2 metal compound are used as the reaction catalyst.
The method for producing a polyester resin according to [1] or [2].
[4] A polyester resin comprising a branched structure represented by the following general formula (1).

(In general formula (1), 1 to 3 of X1 to X4 are represented by the following general formula (2)

(In general formula (2), n is an integer of 0 to 5, k is an integer of 1 to 300, and R is the following general formula (3).

Or the following general formula (4)

It is represented by )
Among X1 to X4 in the general formula (1), those other than the general formula (2) are represented by the following general formula (5).

(In general formula (5), n is 0-5 and m is 8-30.)
Or the following general formula (6)

(In General formula (6), n is 0-5, m is 8-30, k is an integer of 1-300.)
It is represented by )

  According to the present invention, the polycondensation reactivity can be achieved by adding a fatty acid ester compound having fatty acid and a polyhydric alcohol as constituent components and / or a polyvalent carboxylic acid ester compound having a polycarboxylic acid and an alcohol as constituent components. Without sacrificing quality, there is little concern about thickening (gelation), and a polyester resin having high fluidity can be produced while maintaining strength properties such as tensile fracture nominal strain strength.

Hereinafter, the present invention will be described in detail. However, the description of each constituent element described below is a representative example of the embodiment of the present invention, and the present invention is not limited thereto.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Moreover, the lower limit value or the upper limit value in this specification means a range including the numerical value of the lower limit value or the upper limit value.

<Production raw materials>
The polyester resin of the present invention is obtained by subjecting a dicarboxylic acid component having terephthalic acid or an ester-forming derivative thereof as a main component and a diol having 1,4 butanediol as a main component to an esterification reaction and / or an ester exchange reaction. It can be obtained by polycondensation reaction.

  The dicarboxylic acid component mainly comprising terephthalic acid or an ester-forming derivative thereof used in the present invention means that terephthalic acid or an ester-forming derivative thereof in the dicarboxylic acid is usually 80 mol% or more. Preferably it is 90 mol% or more, More preferably, it is 95 mol% or more. Examples of other dicarboxylic acids include isophthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, succinic acid, oxalic acid, cyclohexanedicarboxylic acid, and ester-forming derivatives thereof. These may be used alone or in combination of two or more.

The diol mainly composed of 1,4 butanediol used in the present invention means that 1,4 butanediol in the diol is usually 80 mol% or more. Preferably it is 90 mol% or more, More preferably, it is 95 mol% or more. Other diols include alkylene glycols such as ethylene glycol, propylene glycol, neopentyl glycol, hexamethylene glycol, decamethylene glycol, cyclohexanedimethanol, poly (oxy) ethylene glycol, polytetramethylene glycol, and polymethylene glycol. These may be used alone or in combination of two or more, and can be arbitrarily selected according to the purpose.

  The ester-forming derivative used in the present invention is an ester-forming derivative that can form an ester as a diol in the resin production process, and is a lower alkyl ester of terephthalic acid or other dicarboxylic acid, specifically methyl ester, ethyl ester, propyl. Examples include esters and butyl esters. One or two or more of these may be mixed, and can be arbitrarily selected depending on the purpose.

In the present invention, the fatty acid ester compound can exhibit good fluidity while suppressing a branching reaction that may cause gelation. The reason is presumed that the branch reaction in the reaction system is suppressed by the ester bond between the polyhydric alcohol and the fatty acid, and the fatty acid expresses a lubricant effect in the polyester resin. .
Examples of the fatty acid constituting the fatty acid ester used in the present invention include butanoic acid, hexanoic acid, caprylic acid, capric acid, lauric acid, palmitic acid, stearic acid, behenic acid, and montanic acid. And those having 12 to 22 carbon atoms are preferred. When the number of carbon atoms is less than 12, the effect of good fluidity tends to be small. When the number of carbon atoms exceeds 22, the added amount is increased to exhibit the good fluidity effect, which is not preferable in terms of cost.

The polyhydric alcohol component constituting the fatty acid ester in the present invention is a trihydric or higher alcohol, such as pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, sorbitol, glycerin, 2 -Methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, etc. Among them, pentaerythritol and 1,2,4-butanetriol have good fluidity. It is preferably used in that it has low concern about thickening while holding.
In addition, you may add separately the fatty acid and polyhydric alcohol which comprise a fatty-acid ester compound not only as an ester compound but as a single-piece | unit.

The molecular weight of the fatty acid ester compound used in the present invention is preferably 100 to 5000, more preferably 100 to 3000, and most preferably 150 to 1000. If it is less than the lower limit, the effect of good fluidity tends to be small, and if it exceeds the upper limit, the amount added is increased, which is not preferable in terms of cost.
In the present invention, when a polyvalent carboxylic acid ester compound is used, the same effect as that obtained when a fatty acid ester compound is used can be obtained. The reason for this is presumed that the branch reaction in the reaction system is suppressed by the ester bond between the polyvalent carboxylic acid and the alcohol, and the alcohol expresses a lubricant effect in the polyester resin. The

The polyvalent carboxylic acid constituting the polyvalent carboxylic acid ester compound used in the present invention is a trivalent or higher carboxylic acid, such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2, 3-propanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5 -Benzenetetracarboxylic acid (pyromellitic acid) and the like, among them trimellitic acid, 1,2,3,4-butanetetracarboxylic acid
Is preferably used from the viewpoint that good fluidity is exhibited without impairing reactivity.

Examples of the alcohol constituting the polyvalent carboxylic acid ester compound used in the present invention include propanol, butanol, hexanol, capryl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, linoleyl alcohol, and the like. Among them, those having 12 to 22 carbon atoms are preferably used. When the number of carbon atoms is less than 12, the effect of good fluidity is small, and when the number of carbon atoms exceeds 22, the added amount is increased to exhibit the good fluidity effect, which is not preferable in terms of cost.

In addition, you may add separately the polyvalent carboxylic acid and alcohol which comprise a polyvalent carboxylic acid ester compound not only as an ester compound but as a single-piece | unit.
The molecular weight of the polyvalent carboxylic acid ester compound used in the present invention is preferably 100 to 5000, more preferably 100 to 3000, and most preferably 150 to 1000. If it is less than the lower limit, the effect of good fluidity tends to be small, and if it exceeds the upper limit, the amount added is increased, which is not preferable in terms of cost.

The amount of the fatty acid ester compound or the polyvalent carboxylic acid ester compound is preferably 10.0 parts by weight or less, more preferably 5.0 parts by weight or less, particularly preferably 3 parts per 100 parts by weight of the obtained polyester resin. 0.0 parts by weight or less. On the other hand, it is preferably 0.2 parts by weight or more, more preferably 0.35 parts by weight or more, and particularly preferably 0.5 parts by weight or more. If the upper limit is exceeded, gelation may occur. Moreover, when it is less than the lower limit, it tends to be difficult to obtain a polyester resin having high fluidity.

  In the present invention, there is little concern about thickening (gelation), and the polyester resin having high fluidity while maintaining strength properties such as tensile fracture nominal strain strength is a branched structure represented by the following general formula (1). It is a polyester resin containing a body.

(In general formula (1), 1 to 3 of X1 to X4 are represented by the following general formula (2)

(In general formula (2), n is an integer of 0 to 5, k is an integer of 1 to 300, and R is the following general formula (3).

Or the following general formula (4)

It is represented by )
Among X1 to X4 in the general formula (1), those other than the general formula (2) are represented by the following general formula (5).

(In general formula (5), n is 0-5 and m is 8-30.)
Or the following general formula (6)

(In General formula (6), n is 0-5, m is 8-30, k is an integer of 1-300.)
It is represented by )
The branched structure of the general formula (1) has a structure derived from a polyhydric alcohol. Examples of the polyhydric alcohol include pentaerythritol, glycerin, trimethylolpropane, and the like. It is preferable as an effect of developing the sex.

In general formula (2) and (6), k is an integer of 1-300. K is preferably in the range of 1 to 150, more preferably 1 to 100 in that there is little concern about thickening (gelation).
In the general formulas (2), (5) and (6), n is an integer of 0 to 5, and n is preferably 1 to 2 in that good fluidity is exhibited without impairing reactivity. Is preferred.

Further, in the general formulas (5) and (6), m is an integer of 8 to 30, and m is preferably in the range of 12 to 22 in terms of exhibiting good fluidity.
In the general formula (1), when there are a plurality of general formulas (2) as X1 to X4, R in the general formula (2) may be the same or different from each other.
In general formula (1), it is preferable that at least one of X1 to X4 is general formula (6). When two or more of X1 to X4 are represented by the general formula (5) or (6), the general formula (5) and the general formula (6) may be mixed, or all may be represented by the general formula (5) or ( 6).

<Manufacturing method>
Hereinafter, the production method of the polyester resin will be described by taking PBT as an example.
As a known production method of PBT, there are a so-called direct polymerization method using terephthalic acid and 1,4-BG as main raw materials, and a transesterification method using terephthalic acid dialkyl ester and 1,4-BG as main raw materials.

  In the present invention, a conventionally known method, except that a fatty acid ester compound containing fatty acid and polyhydric alcohol as constituent components and / or a polyvalent carboxylic acid ester compound containing polyhydric carboxylic acid and alcohol as constituent components is added to the reaction system, That is, an esterification step in which an esterification reaction and / or a transesterification reaction between a dicarboxylic acid component having terephthalic acid or an ester-forming derivative thereof as a main component and a diol having 1,4 butanediol as a main component, and an ester It can be carried out by a method of obtaining a polyester through a polycondensation step in which a polycondensation reaction is performed on the oligomer obtained in the conversion step.

In the present invention, an oligomer is a polyester resin having a number average molecular weight of 500 to 10,000.
In the present invention, the reaction system is an esterification step or a polycondensation step. The esterification step includes an esterification reaction tank and an apparatus connected to the esterification reaction tank by piping, and the polycondensation process includes a polycondensation reaction tank and an apparatus connected to the polycondensation reaction tank by piping.

The esterification step is optional as long as the esterification reaction and / or transesterification reaction can proceed, and the temperature is 120 ° C. or higher, preferably 150 ° C. or higher, while 245 ° C. or lower, preferably 230 ° C. or lower. It is. The reaction time is 2 to 8 hours, preferably 2 to 6 hours, and more preferably 2 to 4 hours.
The esterification step produces an oligomer in which a diol having 1,4 butanediol as a main component and a dicarboxylic acid component having terephthalic acid or an ester-forming derivative thereof as a main component are reacted. And in the polycondensation process mentioned later, this oligomer polycondensation reaction is performed.

  In the polycondensation process, the oligomer obtained in the esterification process is subjected to a polycondensation reaction. The polycondensation reaction is usually performed by a melt polycondensation reaction. The conditions in the polycondensation step are arbitrary as long as the polycondensation reaction can proceed. The reaction temperature (internal temperature) during the polycondensation reaction is preferably 245 ° C. or lower, more preferably 240 ° C. or lower, on the other hand, preferably 230 ° C. or higher, more preferably 235 ° C. or higher. If the reaction temperature exceeds the upper limit, there is a high possibility of thickening during production, and the color tone tends to deteriorate. If the reaction temperature is less than the lower limit, the polycondensation reactivity tends to deteriorate.

  Further, the pressure in the polycondensation step is preferably reduced pressure. Specifically, it is 10 Torr or less, preferably 3 Torr. Furthermore, the polycondensation reaction time is preferably 2 to 8 hours. In the polycondensation step, a diol having 1,4 butanediol as a main component, a fatty acid ester compound having a fatty acid and a polyhydric alcohol as constituent components and / or a polyvalent carboxylic acid ester compound having a polycarboxylic acid and an alcohol as constituent components And a polyester obtained by polycondensation reaction of a dicarboxylic acid component containing terephthalic acid or an ester-forming derivative thereof as a main component.

  In the present invention, the addition time of the fatty acid ester compound containing fatty acid and polyhydric alcohol as the constituent components and / or the polyvalent carboxylic acid ester compound containing polyhydric carboxylic acid and the alcohol as the constituent components is the start time of the esterification reaction or transesterification reaction. The esterification reaction or the transesterification reaction, during the esterification reaction or the transesterification reaction, or during the polycondensation reaction may be carried out.

In the esterification reaction, transesterification reaction, or polycondensation reaction, the addition timing of the titanium compound used as the reaction catalyst is the beginning of the esterification reaction or transesterification reaction, during the esterification reaction or transesterification reaction, esterification reaction or ester Although there may be after the exchange reaction or at the time of the polycondensation reaction, it is preferable to add them separately at the beginning of the esterification reaction or transesterification reaction and before the polycondensation reaction.

  Moreover, the compound of a periodic table group 2 metal can also be used as a promoter. Periodic table group 2 metal compounds may be added at the start of esterification or transesterification, during esterification or transesterification, after esterification or transesterification, or during polycondensation However, it is preferable in terms of polycondensation and color tone to be added at the end of the transesterification and before the start of polymerization.

  Titanium compounds used in the present invention are inorganic titanium compounds such as titanium oxide and titanium tetrachloride, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, Tetraalkyl titanates such as tetracyclohexyl titanate and tetrabenzyl titanate are preferable, and tetra-n-butyl titanate is particularly preferable. In addition, a titanium compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The addition amount of the titanium compound is preferably 20 ppm by weight or more, more preferably 30 ppm by weight or more, on the other hand, preferably 100 ppm by weight or less, more preferably 70 ppm by weight or less as titanium atoms with respect to the polyester resin obtained. . If the upper limit is exceeded, not only the color tone and thermal stability tend to deteriorate, but also the solution haze and foreign matter tend to increase due to the deactivation of the titanium catalyst. Moreover, polycondensation reactivity will deteriorate that it is less than a lower limit.
The content of titanium atoms in the polyester resin is measured by ICP (Inductively Coupled Plasma) -MS (Mass Spectrometer) method after recovering the metal in the polymer by wet ashing.

  Examples of the metal atom of the Group 2 metal compound used in the present invention include beryllium, magnesium, calcium, strontium, and barium. Of these, magnesium and calcium compounds are preferred from the viewpoint of handling and availability, and catalytic effect. Examples of the magnesium compound include magnesium acetate and hydrates thereof, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate, and the like. Examples of the calcium compound include calcium acetate and its hydrate, calcium hydroxide, calcium carbonate and the like. Of these, magnesium acetate is particularly preferred. In addition, the compound of a periodic table group 2 metal may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The amount of Group 2 metal compound added is preferably 5 ppm by weight or more, more preferably 20 ppm by weight or more, more preferably 100 ppm by weight or less, more preferably 70 ppm by weight as a metal atom with respect to the resulting polyester resin. It is as follows. If it is less than the lower limit, the improvement in the polycondensation reaction rate tends to be small, the terminal carboxyl group concentration also increases, and the hydrolysis resistance and color tone tend to deteriorate. If the upper limit is exceeded, the polycondensation reaction rate decreases, and hydrolysis resistance and color tone tend to deteriorate.
In addition, content of the metal atom of the compound of the periodic table group 2 metal in a polyester resin can be measured similarly to the measuring method of content of a titanium atom.

In the present invention, a heat stabilizer can be added to the reaction system. Although there is no restriction | limiting in particular in the heat stabilizer to be used, A hindered phenol type heat stabilizer is preferable. Examples of the hindered phenol heat stabilizer include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4, Examples include 6-tris- (3,5-di-t-butyl-4-hydroxybenzyl) benzene. Among these, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is more preferable in terms of thermal stability during melt residence. In addition, a hindered phenol-based heat stabilizer may be used alone, or 2
You may use a seed | species or more together by arbitrary combinations and ratios.

  The intrinsic viscosity of the polyester resin of the present invention, particularly PBT, is not particularly limited, but is preferably 0.60 dL / g or more, more preferably from the viewpoint of mechanical properties, pelletization stability, moldability, and fluidity. It is 0.70 dL / g or more. When the intrinsic viscosity of PBT is less than the lower limit, the fluidity is improved, but the amount of fine powder generated is increased during pelletization, and it is difficult to obtain good mechanical properties as quality.

  The terminal carboxyl group concentration of the PBT of the present invention is not particularly limited, but the lower limit is preferably 1 equivalent / ton, more preferably 2 equivalent / ton, and particularly preferably 3 equivalent / ton. Most preferably, it is 5 equivalents / ton, and the upper limit is preferably 50 equivalents / ton, more preferably 40 equivalents / ton, particularly preferably 30 equivalents / ton, and 25 equivalents / ton. Most preferably. When the terminal carboxyl group concentration of PBT is not more than the upper limit value, the hydrolysis resistance of PBT tends to be good, and when it is more than the lower limit value, polycondensation reactivity tends to be good.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example at all unless the summary is exceeded. In addition, the measurement method of the physical property and evaluation item which were employ | adopted in the following examples is as follows.
<Intrinsic viscosity (IV) dL / g>
It calculated | required in the following way using the Ubbelohde type viscometer. That is, using a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1), the number of seconds falling of only the polymer solution having a concentration of 1.0 g / dL and the solvent at 30 ° C. was measured, and the following formula (1) Asked.

IV = ((1 + 4K _H η _sp ) ^0.5 −1) / (2K _H C) (1)
(Where η _SP = η / η ₀ −1, η is the polymer solution falling seconds, η ₀ is the solvent dropping seconds, C is the polymer solution concentration (g / dL), and K _H is the Huggins constant. there .K _H adopted the 0.33.)

<Terminal carboxyl group concentration (AV) equivalent / ton>
After pulverizing the sample, it was dried at 140 ° C. for 15 minutes in a hot air dryer, and 0.1 g was accurately weighed from the sample cooled to room temperature in a desiccator, taken into a test tube, 3 ml of benzyl alcohol was added, The solution was dissolved at 195 ° C. for 3 minutes while blowing dry nitrogen gas, and then 5 ml of chloroform was gradually added and cooled to room temperature. One to two drops of phenol red indicator were added to this solution, and titrated with a 0.1N sodium hydroxide benzyl alcohol solution with stirring while blowing dry nitrogen gas, and the procedure was terminated when the color changed from yellow to red. Moreover, the same operation was implemented as a blank, without melt | dissolving a polyester resin sample, and the terminal carboxyl group density | concentration (acid value) was computed by the following formula | equation (2).

Terminal carboxyl concentration (equivalent / ton) = (ab) × 0.1 × f / w (2)
(Where a is the amount of 0.1N sodium hydroxide in benzyl alcohol solution required for titration (μl), b is the amount of 0.1N sodium hydroxide in benzyl alcohol solution required for titration with a blank. The amount (μl), w is the amount of the polyester resin sample (g), and f is the titer of 0.1N sodium hydroxide in benzyl alcohol.)
In addition, the titer (f) of the benzyl alcohol solution of 0.1N sodium hydroxide was calculated | required with the following method. Collect 5 ml of methanol in a test tube, add 1-2 drops as an indicator of an ethanol solution of phenol red, Titration was performed with 0.4 ml of 1N sodium hydroxide in benzyl alcohol to the color change point, and then 0.1N hydrochloric acid solution having a known titer was used as a standard solution.
2 ml was collected and added, and again titrated with a 0.1 N sodium hydroxide benzyl alcohol solution to the color change point (the above operation was carried out under dry nitrogen gas blowing). The titer (f) was calculated by the following formula (3).

    Titer (f) = Titer of 0.1N aqueous hydrochloric acid × Amount of collected 0.1N aqueous hydrochloric acid (μl) / Titration of 0.1N sodium hydroxide in benzyl alcohol (μl) (3)

<Pellet color tone (b value)>
Reference Example 1 of JIS Z8730 using pelletized polyester filled in a cylindrical powder measurement cell having an inner diameter of 30 mm and a depth of 12 mm and using a colorimetric color difference meter Z300A (manufactured by Nippon Denshoku Industries Co., Ltd.) The b value by the color coordinate of Hunter's color difference formula in the Lab display system described in the above was obtained as a simple average value of four values measured by rotating the measurement cell by 90 degrees by the reflection method.

<Melt viscosity Pa · sec>
Measurement of Melt Viscosity Using a Toyo Seiki Capillograph (Capillograph 1B), melt viscosity was measured under the conditions of a temperature of 270 ° C., a shear rate of 10 to 10,000 / sec, a capillary length of 10 mm, and a capillary diameter of 1 mm. In Examples and Comparative Examples, the melt viscosity value is typically 6080 / sec.

<Tensile yield strength MPa, Nominal tensile strain%>
Using an injection molding machine (Sumitomo Heavy Industries, Ltd .: Model S-75MIII), cylinder temperature 2
An ISO test piece of the resin composition was molded at 50 ° C. and a mold temperature of 80 ° C., and the tensile yield strength and the tensile strain at break were measured according to ISO 527.

<Identification of polymer structure>
The polymer structure was identified according to the following NMR measurement conditions. About 20 mg of the sample was dissolved in 0.75 ml of a deuterated chloroform / heavy hexafluoroisopropanol (7/3) mixed solvent, 25 μl of deuterated pyridine was added, and the sample was transferred to an NMR sample tube having an outer diameter of 5 mm. 1H NMR spectra were measured at room temperature using a Bruker AVANCE400 spectrometer.

(Reference Example 1)
In a reaction vessel equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer, a distillation pipe, and a vacuum outlet, 132 parts by weight of dimethyl terephthalate (manufactured by Teijin), 74 parts by weight of 1,4-butanediol and a catalyst First, 0.59 parts by weight of a 1,4-butanediol solution in which 6% by weight of tetra-n-butyl titanate was dissolved in advance (33 ppm by weight as titanium atoms with respect to the obtained PBT) was added, and the system was replaced with nitrogen by vacuum-replacement. It was under atmosphere.

The system was heated to 150 ° C. with stirring, and reacted for 3 hours while distilling off the methanol produced by the transesterification reaction while raising the temperature to 210 ° C. to obtain an oligomer.
Subsequently, 1.08 parts by weight of a 1,4-butanediol solution in which 6% by weight of tetra-n-butyl titanate was dissolved in advance as a catalyst (61 ppm by weight as titanium atoms with respect to the obtained PBT) was charged, and magnesium acetate 4 0.64 parts by weight of a 1,4-butanediol solution in which 10% by weight of a hydrate had been dissolved in advance (48 ppm by weight as Mg atoms relative to the obtained PBT) was charged.

Next, the temperature was raised to 240 ° C. over 1 hour, and the pressure was reduced to 0.4 kPa over 1.5 hours, and a polycondensation reaction was performed at the same degree of pressure reduction. When the predetermined stopping power was reached, the reaction system was returned to normal pressure to complete the polycondensation reaction. The obtained PBT was extracted as a strand from the bottom of the reaction vessel, submerged in water at 10 ° C., and then the strand was cut with a cutter to obtain a pellet-like PBT. The intrinsic viscosity (IV) of the obtained PBT was 0.70 dL / g. In the following examples and comparative examples, the polycondensation reaction was terminated when the same stopping power as in this reference example was reached.

[Example 1]
In a reaction vessel equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer, a distillation pipe, and a vacuum outlet, 132 parts by weight of dimethyl terephthalate (manufactured by Teijin), 74 parts by weight of 1,4-butanediol and a catalyst First, 0.59 parts by weight of a 1,4-butanediol solution in which 6% by weight of tetrabutyl titanate was dissolved in advance (33 ppm by weight as titanium atoms with respect to the obtained PBT) was added, and fatty acids were stearic acid and polyhydric alcohol as constituent components Is pentaerythritol, and 1.50 parts by weight of PBT from which pentaerythritol monostearate, a fatty acid ester compound in which one molecule of stearic acid is esterified per one molecule of pentaerythritol, is charged, and the system is replaced by nitrogen-reduced pressure. The inside was made into nitrogen atmosphere.

The system was heated to 150 ° C. with stirring, and reacted for 3 hours while distilling off the methanol produced by the transesterification reaction while raising the temperature to 210 ° C. to obtain an oligomer.
Subsequently, 1.08 parts by weight of a 1,4-butanediol solution in which 6% by weight of tetra-n-butyl titanate was dissolved in advance as a catalyst (61 ppm by weight as titanium atoms with respect to the obtained PBT) was charged, and magnesium acetate 4 0.64 parts by weight of a 1,4-butanediol solution in which 10% by weight of a hydrate had been dissolved in advance (48 ppm by weight as Mg atoms relative to the obtained PBT) was charged.

  Next, the temperature was raised to 240 ° C. over 1 hour, and the pressure was reduced to 0.4 kPa over 1.5 hours, and a polycondensation reaction was performed at the same degree of pressure reduction. When the same power as in Reference Example 1 was reached, the reaction system was returned to normal pressure to complete the polycondensation reaction. The obtained PBT was extracted as a strand from the bottom of the reaction vessel, submerged in water at 10 ° C., and then the strand was cut with a cutter to obtain a pellet-like PBT.

  The obtained PBT had an intrinsic viscosity (IV) of 0.70 dL / g and a terminal carboxyl group concentration (AV) of 24 equivalents / ton. The polycondensation time was defined as the time from the start of pressure reduction to the end of the polycondensation reaction, and the polycondensation reaction rate was defined as the intrinsic viscosity / polycondensation reaction time. The polycondensation reaction rate was 0.18 dL / g / h. The tensile yield strength was 53 MPa, and the tensile strain at break was 2.7%. The melt viscosity was 16 Pa · sec at a shear rate of 6080 (/ sec). The results are shown in Table 1.

[Example 2]
Example 1 except that the fatty acid ester compound in Example 1 was changed to pentaerythritol distearate in which two molecules of stearic acid were esterified per molecule of pentaerythritol, and 2.50 parts by weight were charged to the resulting PBT. In the same manner as above, PBT was obtained. Various analysis results are shown in Table 1.

[Example 3]
PBT was obtained in the same manner as in Example 1 except that the amount of pentaerythritol monostearate added in Example 1 was 10.0 parts by weight. Various analysis results are shown in Table 1.
[Example 4]
PBT was obtained in the same manner as in Example 1 except that the amount of pentaerythritol monostearate added in Example 1 was 0.3 parts by weight. Various analysis results are shown in Table 1.

[Example 5]
PBT was obtained in the same manner as in Example 1 except that 1,4-butanediol in which magnesium acetate tetrahydrate was dissolved was not added. Various analysis results are shown in Table 1.
[Comparative Example 1]
A PBT was obtained in the same manner as in Example 1 except that 1.50 parts by weight of PBT from which pentaerythritol was obtained in place of the fatty acid ester compound in Example 1 was charged. The obtained PBT had a reduced nominal tensile strain. Various analysis results are shown in Table 1.

  According to the present invention, good mechanical properties can be maintained and fluidity during melt molding can be improved. In particular, it is effective for injection molded products having a complicated structure such as electrical / electronic parts and precision equipment parts.

Claims (4)

  Esterification step for performing esterification reaction and / or transesterification reaction of dicarboxylic acid component having terephthalic acid or its ester-forming derivative as a main component and diol having 1,4 butanediol as a main component, and esterification step In the method for producing a polyester through a polycondensation step in which a polycondensation reaction is performed on the oligomer obtained by the above, a fatty acid ester compound and / or a polycarboxylic acid and an alcohol having fatty acid and polyhydric alcohol as constituent components in the reaction system A method for producing a polyester resin, comprising adding a polyvalent carboxylic acid ester compound.   The method for producing a polyester resin according to claim 1, wherein 0.2 to 10 parts by weight of the fatty acid ester compound and / or the polyvalent carboxylic acid ester compound is added to a reaction system with respect to 100 parts by weight of the obtained polyester resin. In the esterification reaction, transesterification reaction, or polycondensation reaction, a reaction catalyst is used,
The manufacturing method of the polyester resin of Claim 1 or 2 which uses a titanium compound and a periodic table group 2 metal compound as a reaction catalyst. A polyester resin comprising a branched structure represented by the following general formula (1).

(In general formula (1), 1 to 3 of X1 to X4 are represented by the following general formula (2)

(In general formula (2), n is an integer of 0 to 5, k is an integer of 1 to 300, and R is the following general formula (3).

Or the following general formula (4)

It is represented by )
Among X1 to X4 in the general formula (1), those other than the general formula (2) are represented by the following general formula (5).

(In general formula (5), n is 0-5 and m is 8-30.)
Or the following general formula (6)

(In General formula (6), n is 0-5, m is 8-30, k is an integer of 1-300.)
It is represented by )