JP4030206B2 - Polyester manufacturing method - Google Patents

Description

【００６５】
これらの実施例および比較例で示されるように、重縮合触媒として(i)亜鉛化合物と、(ii)アルカリ金属、アルカリ土類金属、周期律表第４周期の遷移金属およびアルミニウムから選ばれる少なくとも１種の金属の化合物とからなる触媒を用いた実施例１〜３のポリエステルの製造方法では、亜鉛化合物を単独で触媒として用いた比較例１と比較して短時間で重縮合反応を完了できることがわかる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a polyester that is suitably used for applications such as bottles, films, and sheet molding. More specifically, the present invention relates to polycondensation of aromatic dicarboxylic acids and aliphatic diols at a high polymerization rate. It is related with the manufacturing method of polyester which can do.
[0002]
TECHNICAL BACKGROUND OF THE INVENTION
Polyester, particularly polyethylene terephthalate (PET), is excellent in mechanical strength, heat resistance, transparency and gas barrier properties, and is suitably used as a material for beverage filling containers such as juices, soft drinks and carbonated drinks.
[0003]
Such polyester is usually produced using aromatic dicarboxylic acids such as terephthalic acid and aliphatic diols such as ethylene glycol as raw materials. Specifically, first, a low-order condensate (ester low polymer) is formed by an esterification reaction of an aromatic dicarboxylic acid and an aliphatic diol, and then this low-order condensate is formed in the presence of a polycondensation catalyst. It is produced by deglycolization reaction (liquid phase polycondensation) to increase the molecular weight, and further solid phase polycondensation.
[0004]
The polyester produced in this way is generally supplied to a molding machine such as an injection molding machine to form a hollow molded body preform, and then the preform is inserted into a mold having a predetermined shape and stretch blow molded to form a hollow molded container. Has been.
[0005]
By the way, in the manufacturing method of the above polyesters, an antimony compound, a germanium compound, etc. were used as a polycondensation catalyst.
However, when an antimony compound is used, there are some problems in terms of heat resistance and transparency of the resulting polyester as compared with the case where a germanium compound is used.
[0006]
In addition, since germanium compounds are quite expensive, there is a problem that the production cost of polyester becomes high, and in order to lower the production cost, for example, a process such as collecting and reusing germanium compounds scattered during polymerization has been studied. Yes.
[0007]
Further, although it has been proposed to use a zinc compound (see, for example, JP-A-53-54293), a known catalyst is separately added in the polycondensation stage.
[0008]
The present inventor conducted intensive studies on the polycondensation catalyst in the production of polyester in view of the above-described conventional technology. As the polycondensation catalyst, a zinc compound, an alkali metal, an alkaline earth metal, a fourth periodic table By using a transition metal and a compound of at least one metal selected from aluminum,
It has been found that a polyester can be produced with a higher catalytic activity than when a germanium compound is used without using an expensive germanium compound, and the present invention has been completed.
[0009]
OBJECT OF THE INVENTION
An object of the present invention is to provide a method for producing a polyester capable of polycondensing aromatic dicarboxylic acids and ethylene glycols with high catalytic activity.
[0010]
SUMMARY OF THE INVENTION
The method for producing the polyester according to the present invention comprises:
In producing a polyester by polycondensing an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol or an ester-forming derivative thereof in the presence of a polycondensation catalyst,
As a polycondensation catalyst
(i) a zinc compound;
(ii) A compound of at least one metal selected from alkali metals and magnesium ;
It is characterized by using the catalyst which consists of.
[0011]
The (i) zinc compound is preferably zinc acetate or zinc carbonate. (Ii) The compound of at least one metal selected from alkali metal and magnesium, at least one metal carbonates selected from alkali metal and magnesium, acetate, phosphate or phosphite salts.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereafter, the manufacturing method of polyester of this invention is demonstrated concretely.
Polycondensation catalyst First, the polycondensation catalyst used in the method for producing a polyester according to the present invention will be described.
[0013]
In the present invention, as a polycondensation catalyst
(i) a zinc compound;
(ii) a catalyst comprising an alkali metal, an alkaline earth metal, a compound of at least one metal selected from the transition metals in the fourth period of the periodic table and aluminum (hereinafter also referred to as (ii) a metal compound). Is used.
[0014]
(i) Examples of the zinc compound include carboxylates such as zinc acetate, zinc carbonate, zinc acetylacetonate, and zinc alkoxide, and zinc acetate and zinc carbonate are particularly preferable.
[0015]
Further, (ii) as the metal compound, carbonate, acetate, phosphate or phosphorous of at least one metal selected from alkali metals, alkaline earth metals, transition metals in the fourth period of the periodic table and aluminum Acid salts and the like are preferably used.
[0016]
Specific examples of such (ii) metal compounds include lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, aluminum carbonate, lithium acetate, sodium acetate, potassium acetate, magnesium acetate. , Calcium acetate, strontium acetate, barium acetate, aluminum acetate, lithium phosphate, sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, barium phosphate, aluminum phosphate, lithium phosphite, phosphorous Examples include sodium phosphate, potassium phosphite, magnesium phosphite, calcium phosphite, strontium phosphite, barium phosphite, aluminum phosphite, cobalt acetate, manganese acetate, and nickel acetate. . Of these, sodium phosphate, potassium phosphate, sodium phosphite, and potassium phosphite are particularly preferable.
[0017]
Two or more kinds of the above (ii) metal compounds may be used.
The molar ratio (i) / (ii) between (i) zinc compound and (ii) metal compound in the polycondensation catalyst used in the present invention is 50/1 to 1/50, preferably 20 in terms of metal atom. It is desirable that it is / 1 to 1/10.
[0018]
Such a polycondensation catalyst is based on aromatic dicarboxylic acid in terms of metal atoms in the polycondensation catalyst, (i) zinc compound is 0.001 to 0.2 mol%, preferably 0.002 to 0.1 mol%, (ii) It is desirable to use the metal compound in an amount of 0.005 to 0.3 mol%, preferably 0.010 to 0.2 mol%.
[0019]
By using such a polycondensation catalyst, polycondensation of aromatic dicarboxylic acids and aliphatic diols can be performed with high polymerization activity.
Method for producing polyester The method for producing a polyester according to the present invention includes an esterification step and a polycondensation step, and is not particularly limited except that a polycondensation catalyst as described above is used. .
[0020]
In such a process, the polycondensation catalyst only needs to be present during the polycondensation reaction. Even if it is added in any one of the polycondensation step, esterification step, raw material slurry preparation step, etc., it is divided into a plurality of steps. May be added. Alternatively, a catalyst prepared by reacting (i) a zinc compound and (ii) a metal compound in advance may be used.
[0021]
In the present invention, a known additive, for example, a colorant such as a stabilizer, a release agent, an antistatic agent, a dispersant, a dye or pigment may be added at any stage during the production of the polyester. These additives may be added by a master batch before molding.
[0022]
The polyester composition thus obtained is melt-molded and used for bottles, sheets, films and the like.
[0023]
[Raw materials]
The method for producing a polyester according to the present invention uses an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol or an ester-forming derivative thereof as raw materials.
[0024]
Examples of the aromatic dicarboxylic acid include terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, and the like.
[0025]
Examples of the aliphatic diols include ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanemethylene glycol, and dodecamethylene glycol.
[0026]
In the present invention, for example, terephthalic acid and ethylene glycol may be used to produce homopolyethylene terephthalate, and terephthalic acid and dicarboxylic acids other than terephthalic acid and diols other than ethylene glycol and ethylene glycol may be used. Copolyesters can also be produced.
[0027]
Moreover, in this invention, aliphatic dicarboxylic acids, such as adipic acid, sebacic acid, azelaic acid, and decanedicarboxylic acid, alicyclic dicarboxylic acids, such as cyclohexane dicarboxylic acid, etc. can also be used as a raw material with aromatic dicarboxylic acid.
[0028]
Furthermore, alicyclic glycols such as cyclohexanedimethanol, bisphenol, hydroquinone, and aromatic diols of 2,2-bis (4-β-hydroxyethoxyphenyl) propanes can be used as raw materials together with aliphatic diols. it can.
[0029]
In the production method of the present invention, either a batch method or a continuous method may be employed. Hereinafter, although an example of the manufacturing method of a continuous system is demonstrated, this invention is not limited to these.
[0030]
[Esterification process]
First, when producing polyester, an aromatic dicarboxylic acid or an ester-forming derivative thereof is esterified with an aliphatic diol or an ester-forming derivative thereof.
[0031]
Specifically, a slurry containing an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol or an ester-forming derivative thereof is prepared.
Such a slurry contains 1.005 to 1.4 mol, preferably 1.01 to 1.3 mol of an aliphatic diol or an ester-forming derivative thereof, per 1 mol of an aromatic dicarboxylic acid or an ester-forming derivative thereof. This slurry is continuously supplied to the esterification reaction step.
[0032]
The esterification reaction is preferably performed using an apparatus in which two or more reactors are connected in series under conditions where the aliphatic diol is refluxed while removing water generated by the reaction from the system using a rectification column. Is desirable.
[0033]
When the esterification reaction step is performed in multiple stages, the first stage esterification reaction is usually a reaction temperature of 240 to 270 ° C, preferably 245 to 265 ° C, and a pressure of 0.2 to 3 kg / cm ² G, preferably Is carried out under conditions of 0.5 to ² kg / cm ² G, and the esterification reaction at the final stage is usually a reaction temperature of 250 to 280 ° C., preferably 255 to 275 ° C., and a pressure of 0 to 1.5 kg / It is carried out under conditions of cm ² G, preferably 0 to 1.3 kg / cm ² G.
[0034]
Therefore, when the esterification reaction is performed in two stages, the esterification reaction conditions of the first stage and the second stage are within the above ranges, respectively, and when the esterification reaction is performed in three stages or more, the second stage. The esterification reaction conditions from the first stage to the stage before the last stage may be any conditions between the reaction conditions of the first stage and the reaction conditions of the last stage.
[0035]
For example, when the esterification reaction is carried out in three stages, the reaction temperature of the second stage esterification reaction is usually 245 to 275 ° C, preferably 250 to 270 ° C, and the pressure is usually 0 to 2 kg / cm ² G, preferably 0.2 to 1.5 kg / cm ² G may be used.
[0036]
Although the esterification reaction rate in each of these stages is not particularly limited, it is preferable that the degree of increase in the esterification reaction rate in each stage is smoothly distributed, and further in the esterification reaction product in the final stage. Usually, it is desirable to reach 90% or more, preferably 93% or more.
[0037]
By this esterification step, an esterified product (low-order condensate) of an aromatic dicarboxylic acid and an aliphatic diol is obtained, and the number-average molecular weight of this low-order condensate is about 500 to 5,000.
[0038]
Such esterification reactions include not only raw materials such as aromatic dicarboxylic acids and aliphatic diols, but also tertiary amines such as triethylamine, tri-n-butylamine, and benzyldimethylamine, tetraethylammonium hydroxide, and tetrahydroxide. Quaternary ammonium hydroxide such as n-butylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, trimethylbenzylammonium hydroxide, and basic such as lithium carbonate, sodium carbonate, potassium carbonate, sodium acetate A compound may be added, and the reaction may be carried out in the presence of the polycondensation catalyst described above.
[0039]
When, for example, terephthalic acid and ethylene glycol are esterified in the presence of such a basic compound, for example, polyethylene terephthalate having a small content of dioxyethylene terephthalate component units can be obtained.
[0040]
The low-order condensate obtained in the esterification step as described above is then supplied to the polycondensation (liquid phase polycondensation) step.
[Liquid phase polycondensation process]
In the liquid phase polycondensation step, in the presence of the polycondensation catalyst, the low-order condensate obtained in the esterification step is reduced to a temperature not lower than the melting point of the polyester (usually 250 to 280 ° C.). The polycondensation is carried out by heating. The polycondensation reaction is desirably performed while distilling off unreacted aliphatic diol out of the reaction system.
[0041]
The polycondensation reaction may be performed in one stage or may be performed in a plurality of stages. For example, when the polycondensation reaction is performed in a plurality of stages, the first stage polycondensation reaction is performed at a reaction temperature of 250 to 290 ° C, preferably 260 to 280 ° C, and a pressure of 500 to 20 torr, preferably 200 to 30 torr. The final stage polycondensation reaction is carried out under the conditions of a reaction temperature of 265 to 300 ° C., preferably 270 to 295 ° C., and a pressure of 10 to 0.1 torr, preferably 5 to 0.5 torr.
[0042]
When the polycondensation reaction is carried out in three or more stages, the polycondensation reaction from the second stage to the first stage before the last stage is performed between the reaction conditions of the first stage and the reaction conditions of the last stage. It is performed in the condition between. For example, when the polycondensation step is performed in three stages, the second stage polycondensation reaction is usually performed at a reaction temperature of 260 to 295 ° C, preferably 270 to 285 ° C, and a pressure of 50 to 2 torr, preferably 40 Performed under ~ 5torr condition.
[0043]
In such a polycondensation reaction, as described above, the polycondensation catalyst is 0.001 to 0.2 mol%, preferably (i) zinc compound in terms of metal atoms in the polycondensation catalyst with respect to the aromatic dicarboxylic acid. 0.002 to 0.1 mol%, (ii) a compound of at least one metal selected from alkali metals, alkaline earth metals, transition metals in the fourth period of the periodic table and aluminum is 0.005 to 0.3 mol%, preferably 0.010 to It is desirable to be contained in an amount of 0.2 mol%.
[0044]
Such a polycondensation catalyst may be present during the polycondensation reaction.
The polycondensation reaction is desirably performed in the presence of a stabilizer. Specific examples of stabilizers include phosphate esters such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, triphenyl phosphite, trisdodecyl phosphate, trisnonyl phenyl phosphate. Phosphites such as phyto, phosphoric esters such as methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate and organic phosphorus compounds such as phosphoric acid and polyphosphoric acid Is mentioned.
[0045]
The amount of the organic phosphorus compound added is preferably 0.005 to 0.2 mol%, preferably 0.01 to 0.1 mol%, in terms of phosphorus atom in the organic phosphorus compound, with respect to the aromatic dicarboxylic acid. .
[0046]
The intrinsic viscosity [IV] of the polyester obtained by the liquid phase polycondensation process as described above is 0.40 to 1.0 dl / g, preferably 0.50 to 0.90 dl / g. The intrinsic viscosity achieved in each stage excluding the final stage of the liquid phase polycondensation process is not particularly limited, but it is preferable that the degree of increase in intrinsic viscosity in each stage is smoothly distributed.
[0047]
In the present specification, the intrinsic viscosity is calculated from the solution viscosity measured at 25 ° C. after cooling and dissolving 1.2 g of polyester in 15 cc of o-chlorophenol.
[0048]
The polyester obtained in this liquid phase polycondensation step is usually melt extruded and formed into granules (chips).
[Solid phase polycondensation process]
If desired, the polyester obtained in this liquid phase polycondensation step may be further subjected to solid phase polycondensation.
[0049]
The granular polyester supplied to the solid phase polycondensation step may be preliminarily crystallized by heating to a temperature lower than the temperature at which solid phase polycondensation is performed, and then supplied to the solid phase polycondensation step.
[0050]
Such precrystallization can be carried out by heating the granular polyester in a dry state to a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. for 1 minute to 4 hours. Such precrystallization can also be performed by heating the granular polyester at a temperature of 120 to 200 ° C. for 1 minute or more in a steam atmosphere, a steam-containing inert gas atmosphere, or a steam-containing air atmosphere.
[0051]
The precrystallized polyester desirably has a crystallinity of 20 to 50%.
[0052]
In this precrystallization treatment, the so-called polyester solid phase polycondensation reaction does not proceed, and the intrinsic viscosity of the precrystallized polyester is substantially the same as the intrinsic viscosity of the polyester after liquid phase polycondensation, The difference between the intrinsic viscosity of the pre-crystallized polyester and the intrinsic viscosity of the polyester before pre-crystallization is usually 0.06 dl / g or less.
[0053]
The solid phase polycondensation step comprises at least one stage, the temperature is 190 to 230 ° C., preferably 195 to 225 ° C., and the pressure is 1 kg / cm ² G to 10 torr, preferably normal pressure to 100 torr, The reaction is performed in an inert gas atmosphere such as nitrogen, argon, carbon dioxide. Nitrogen gas is desirable as the inert gas used.
[0054]
The intrinsic viscosity of the granular polyester thus obtained is usually 0.60 to 1.00 dl / g, preferably 0.75 to 0.95 dl / g.
[0055]
【The invention's effect】
According to the polyester production method of the present invention,
The polycondensation reaction can be completed in a short time without using a germanium compound that has been conventionally used as a polycondensation catalyst. Therefore, the amount of expensive germanium compound used can be reduced, and the production cost of the polyester can be reduced.
[0056]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
[0057]
[Example 1]
First, ethylene glycol and terephthalic acid were continuously subjected to low-order condensation.
Low-order condensation has a high purity of 6458 parts by weight / hour in a reactor in which 33500 parts by weight of the reaction liquid (during steady operation) is retained in advance and maintained at 260 ° C and 0.9 kg / cm ² G in a nitrogen atmosphere. A slurry prepared by mixing terephthalic acid and 2615 parts by weight of ethylene glycol was continuously supplied with stirring to carry out an esterification reaction. In this esterification reaction, a mixed solution of water and ethylene glycol was distilled off.
[0058]
The esterification reaction product, which is a low-order condensate, was continuously extracted from the system by controlling the average residence time in the reactor to be 3.5 hours.
The number average molecular weight of the low-order condensate of ethylene glycol and terephthalic acid thus obtained was 600 to 1300 (3 to 5 mer).
[0059]
Next, a polycondensation catalyst was added to the low-order condensate thus obtained, and a liquid phase polycondensation reaction was performed.
In this polycondensation reaction, zinc carbonate is converted to 0.021 mol% in terms of zinc atoms, potassium carbonate is converted to 0.042 mol% in terms of potassium atoms, and phosphoric acid is added as a polycondensation catalyst to the terephthalic acid unit in the low-order condensate. It was used in an amount of 0.0105 mol% in terms of phosphorus atom, and was carried out at 285 ° C. and 1 torr.
[0060]
Table 1 shows the time (liquid weight time) required for the intrinsic viscosity [IV] of polyethylene terephthalate to reach 0.56 dl / g.
[0061]
[Example 2]
In Example 1, as the polycondensation catalyst, Example 1 was used except that magnesium carbonate was used instead of potassium carbonate in an amount of 0.042 mol% in terms of magnesium atom with respect to the terephthalic acid unit in the low-order condensate. The polycondensation reaction was performed in the same manner as described above. Table 1 shows the time (liquid weight time) required for the intrinsic viscosity [IV] of polyethylene terephthalate to reach 0.56 dl / g.
[0062]
[Example 3]
In Example 1, as the polycondensation catalyst, dipotassium hydrogen phosphate was used instead of potassium carbonate in an amount of 0.021 mol% based on the terephthalic acid unit in the low-order condensate in terms of potassium atom, and phosphoric acid was used. A polycondensation reaction was carried out in the same manner as in Example 1 except that there was not.
Table 1 shows the time (liquid weight time) required for the intrinsic viscosity [IV] of polyethylene terephthalate to reach 0.56 dl / g.
[0063]
[Comparative Example 1]
In Example 1, a polycondensation reaction was performed in the same manner as in Example 1 except that potassium carbonate was not used as the polycondensation catalyst.
Table 1 shows the time (liquid weight time) required for the intrinsic viscosity [IV] of polyethylene terephthalate to reach 0.56 dl / g.
[0064]
[Table 1]

[0065]
As shown in these Examples and Comparative Examples, as the polycondensation catalyst, at least selected from (i) a zinc compound, (ii) an alkali metal, an alkaline earth metal, a transition metal in the fourth period of the periodic table, and aluminum In the method for producing polyesters of Examples 1 to 3 using a catalyst composed of one kind of metal compound, the polycondensation reaction can be completed in a short time compared with Comparative Example 1 using a zinc compound alone as a catalyst. I understand.

Claims (3)

When an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol or an ester-forming derivative thereof are esterified and polycondensed in the presence of a polycondensation catalyst to produce a polyester,
As a polycondensation catalyst (i) a zinc compound,
(Ii) a compound of at least one metal selected from alkali metals and magnesium ;
A process for producing a polyester comprising using a catalyst comprising:   (I) The method for producing a polyester according to claim 1, wherein zinc acetate or zinc carbonate is used as the zinc compound. (Ii) As a compound of at least one metal selected from alkali metals and magnesium ,
The method for producing a polyester according to claim 1 or 2, wherein carbonate, acetate, phosphate or phosphite of at least one metal selected from alkali metals and magnesium is used.