JPH02302432A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester, excellent in fiber-producing properties and moldability and suitable as a material such as fiber by using a specific amount of a pentaerythritol diphosphite in obtaining the polyester using an organotitanium compound as an ester interchange catalyst. CONSTITUTION:An organotitanium compound (e.g. tetrabutyl titanate) is used as an ester interchange catalyst to provide a polyester from an acid component (e.g. terephthalic acid) and a glycol component (e.g. ethylene glycol) by an ester interchange method. In the process, a pentaerythritol diphosphite [preferably pentaerythritol diphosphite di(2,6-di-tert.-4-methylphenyl) ester, pentaerythritol diphosphite di(2,4-di-tert.-butylphenyl) ester, etc.] in a molar amount of 1.5 to 10 times, preferably 2 to 6 times based on the abovementioned organotitanium compound is added thereto at the time of preferably completing the ester interchange reaction. thereby, activity of the aforementioned organotitanium compound is suppressed to afford a polyester suitable for high speed spinning, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a polymer with excellent moldability. Specifically, when polyester produced by the transesterification method is subjected to high shear during melt molding such as high-speed spinning or injection molding, it suppresses the flow crystallization that tends to occur in polyester, and improves its spinability and moldability. It relates to manufacturing techniques for obtaining good polymers.

(Prior art and problems) Polyester can be produced using the direct esterification method, in which the starting materials are directly esterified from acid and glycol, and then polycondensed.
There is an EI method in which polycondensation is carried out via a transesterification reaction between an acid ester and a glycol. The former esterification reaction proceeds satisfactorily without a catalyst, but the latter Nisdell exchange reaction is difficult to proceed within an economical time without a transesterification catalyst (hereinafter abbreviated as EI catalyst).

Various compounds such as calcium, magnesium, manganese, zinc, cobalt, and titanium are used as the EI catalyst. Conventionally, in order to obtain high-quality polymers, catalysts have been selected from the viewpoints of those with few side reactions and those with little coloring. However, as polymer manufacturing technology has progressed, productivity has tended to become more important than quality. Therefore, as polymers are spun or molded under high-speed conditions, polymers that suppress oriented crystallization and flow crystallization, which were almost unnecessary until now, are now required. .

The above-mentioned EI catalyst has a tendency for the metal residue to become a foreign substance in the polymer and reduce moldability.

Titanium compounds are suitable as EI catalysts because of the requirements that they have good solubility in polymers and exhibit activity even when added in a small amount.

However, while catalysts such as zn, Mg, and Ca are trifunctional, titanium compounds are tetrafunctional, and due to this, the melt flow characteristics of the polymer are slightly inferior.

As yarn spinning and forming speeds have increased in recent years, the disadvantages of titanium compounds have become impossible to ignore.

Apart from these matters, in order to promote the reverse reaction in the polycondensation reaction, it is necessary to add a stabilizer to the polymerization system to deactivate the catalyst activity of the EI catalyst after the EI reaction. Stabilizer (
Phosphorus compounds are commonly used as EI catalyst deactivators (EI catalyst deactivators), and if too much is added, the system becomes acidic and the stability of the polymer decreases. has been used. However, when a titanium compound is used as an EI catalyst, the activity of titanium is too strong, and it is difficult to completely deactivate it even if the phosphorus compound is added in several moles. Since the titanium compound is soluble in the polymer, it does not become an insoluble foreign substance, but since it is not completely deactivated, it may affect the fluidity of the polymer and cause problems such as poor high-speed moldability. .

For example, when performing high-speed spinning, oriented crystallization progresses considerably during the spinning process, making it impossible to increase the spinning speed (spinning speed) sufficiently, and there is also the problem that the drawability is poor in the drawing process that follows spinning. .

In addition, for example, polyester has recently been used as a packaging material for bottles and the like, but when the polymer is injection molded, the preform undergoes fluid crystallization, and if this is oriented and blown, it is difficult to obtain a bottle with excellent transparency. Furthermore, when attempting to obtain a transparent bottle in one blowing process, there are manufacturing problems such as a narrow tolerance range for the molding conditions.

Coincidentally, when a titanium compound was used as an EI catalyst, the inventor added pentaerythritol diphosphite for the purpose of suppressing the catalytic activity. The present invention was achieved by discovering that crystallization is difficult to occur and that spinning and injection molding are possible at high speeds.

Here, as a phosphorus compound, pentaerythritol diphosphite is known as an excellent stabilizer, but it is completely unknown that it affects the moldability of polyester, especially the high-speed moldability due to crystallization. There is no surprising effect.

As a known example of this phosphorus compound, JP-A-58-
No. 91761 (BorgWarner) discloses a polymer composition in which polyalkylene terephthalate is blended with a small amount of pentaerythritol diphosphite ester. As polyalkylene terephthalates, polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are mentioned, and as pentaerythritol diphosphite esters, bis(alkylphenyl) esters, especially bis(dialkylphenyl) esters, dialkyl Esters are indicated as preferred. The effects include thermal reduction in darkness, change in hue, decrease in viscosity (molecule i>, and generation of aldehyde).The amount of phosphite in which these effects are expressed is 0.05~ 10 weight 1%, especially 0.1~
It is disclosed that 0.5% by weight is preferred. However, the influence on the fluidity and moldability of the polymer (apart from suppressing the decrease in molecular weight) is not mentioned.

Furthermore, Plastics Engineering magazine 19
On page 37 of the February 1986 issue, bis(2,4-di-t-butylphenyl) ester was blended into PET as pentaerythritol diphosphite nisdel, and yellowness was measured as an index of thermal stabilization effect. , torque meter rotational torque, intrinsic viscosity, carboxyl terminal group, etc. The compounding amount is 0.1% by weight.

on the other hand. GE Plastics Technical Bulletin 18A
(Stabilixation of recycling
ed PET with Vltranox 626) describes the generation and decomposition mechanism of PET, and in order to suppress thermal decomposition, Ultranox 626 [pentaerythritol bis(2,4-di-t-butylphyll) phosphite manufactured by BorgWarner Co., Ltd.] is described. [trade name] is effective, and the blending amount is about 0.1 to 0.5% by weight, and the stabilizing effects include yellowness and acetaldehyde.

In this PET production reaction part, the catalysts used in the transesterification reaction include Zn, Mn, Li, Ti,
c.

Although titanium catalysts color PET yellow, Zn and Mn are preferred. It is also stated that antimony oxide is generally used as a catalyst in the subsequent polycondensation step.

On the other hand, in JP-A-63-265949, pentaerythritol diphosphite with a specific structure is added to a polymer blend of polyester and polycarbonate to improve the crystallinity, thermal stability, and impact resistance of the blend. It is proposed that. As polyester, easily crystallized PBT is mainly used. The amount of phosphite blended is o, ooi' to 10% by weight based on the blend.
, preferably 0.01 to 3% by weight.

Although these prior art techniques all mention thermal stabilization of polymers, they do not mention anything about melt moldability and high-speed moldability.

(Means for Solving the Problems) The present inventors provide a new polyester production technique for improving the moldability of polyester using a titanium compound as an EI catalyst.

Therefore, the present invention is characterized in that when producing polyester by a transesterification method using an organic titanium compound as a transesterification catalyst, pentaerythritol diphosphite is used in an amount of 2 to 10 times the amount of the titanium catalyst by mole. This is a method for producing polyester.

In the present invention, polynisdel is a polyester whose main acid component is terephthalic acid and whose main glycol component is ethylene glycol.

Here, "main" means 85 mol% or more, preferably 9
It refers to an amount of 5 mol% or more. Therefore, it is possible to contain ester units other than terephthalic acid and ethylene glycol in a range of less than 15 mol%, preferably less than 5 mol%. Such copolymerization components include terephthalic acid, dicarboxylic acids other than ethylene glycol, and diols or oxyacids. Specifically, aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, sodium-sulfoisophthalic acid, dibromoterephthalic acid, etc.; Dicarboxylic acids such as decalindicarboxylic acid and hexahydroterephthalic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid and adipic acid; glycol components such as aliphatic diols such as trimethylene glycol, tetramethylene glycol, Hexamethylene glycol, diethylene glycol, etc.; aromatic diols, such as hydroquinone,
Catechol, naphthalene diol, 1 resorcinol, 4
．． 4'-dihydroxy-diphenyl-sulfone, bisphenol A [2,2-bis(4-hydroxyphenyl)
propane], tetrabromobisphenol A, bishydroxyethoxybisphenol A, etc.; alicyclic diols, such as cyclohexanediol, cyclohexane dimetatool, etc.; aliphatic oxycarboxylic acids, such as glycolic acid, hydroacrylic acid, 3-oxypropionic acid, etc. and monocyclic oxycarboxylic acids such as asiatic acid and quinobic acid; and aromatic oxycarboxylic acids such as salicylic acid, m-oxybenzoic acid, p-oxybenzoic acid, mandelic acid, atrolactic acid and the like.

Furthermore, within the range where the polyester is substantially linear, polyfunctional compounds having a valence of 3 or more, such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid,
Trimesic acid, pyromellitic acid, tricarbalic acid, gallic acid, etc. may be copolymerized, and if necessary, monofunctional compounds such as O-benzoylbenzoic acid, naphthoic acid, etc. may be added.

The polyester of the present invention is produced via a monomer or low polymer mixture by a transesterification reaction between an aromatic dicarboxylic acid dialkyl ester and a glycol.

An organic titanium compound is used as the transesterification catalyst. Organic titanium compounds include tetrabutyl titanate,
Examples include tetrapropyl titanate, tetramethyl titanate, titanium acetate, titanium trimellitate, and potassium titanium oxalate. The amount of the organic titanium compound added is 1 to 10 mmol%, preferably 2 to 5 mmol%, based on the total acid components constituting the polyester.

The polyester of the present invention has an EI rate of 99 when the transesterification reaction is substantially completed with the organic titanium compound.
%), pentaerythritol diphosphite is added to suppress the activity of the titanium compound. Pentaerythritol diphosphites include bisalkylphenyl esters such as bis(2,6-di-t-butyl-
4-methylphenyl) ester, bis(2,4-di-t
-butylphenyl) ester, and snonylphenyl ester, distearyl ester, ditridecyl ester,
Examples include didecyl ester. The latter dialkyl ester has a good hue but is slightly unstable, and the former bis(alkylphenyl) ester has good stability but slightly deteriorates the hue of the polymer. The types of these phosphorus compounds must be selected depending on the intended use of the polymer.

The amount of the phosphorus compound added is 1.5 to 10 times the amount of the organic titanium compound used as the transesterification catalyst. Generally, to deactivate the EI catalyst, an equimolar amount of the phosphorus compound is used (a fraction of the mole of the EI catalyst in order to exist as precipitated particles), but in the case of the present invention, this amount is insufficient. , is used in an amount of 1.5 to 10 times the above, preferably 2 to 6 times the amount. By adding this amount, fluid crystallization and oriented crystallization of the polymer can be suppressed for the first time. This is a new fact that cannot be inferred from conventional technical knowledge of the concept, action, function, etc. of catalyst-stabilizers.

In the present invention, as the polymerization catalyst, antimony compounds, germanium compounds, etc., which are usually used in the production of polynisder, can be used depending on the purpose. If necessary, other additives such as coloring agents, coloring agents, antioxidants, ultraviolet absorbers,
Antistatic agents, flame retardants, etc. can be used.

(Effects of the Invention) The polyester produced by the production method of the present invention is suitable for high-speed spinning, high-speed injection, and blow molding.

Therefore, it is extremely effective as a material for a wide range of polyester molding materials, ie, fibers, films, bottles, etc.

(Examples The present invention will be supplemented by examples below. Part J in the examples means parts by weight. The methods for measuring the properties used in the examples are shown below.

・Intrinsic viscosity: "η" Phenol/tetrachloroethane (60/40 weight ratio)
It was calculated from the solution viscosity measured at 35°C using a mixed solvent.

・Limit spinning speed ability The dried polymer was discharged at 131 g/min from a spinneret having 24 spinning nozzles with a diameter of 9.3 mm at 290°C, and the spinning speed was increased sequentially from 5000 m to 7 minutes every 5 minutes. The maximum speed at which yarn can be wound without yarn breakage per minute is defined as the "limit spinning speed ability."

・Using an injection molding machine with a cylinder temperature of 285°C, the bottle-fogging dry polymer was formed into a cylindrical bottomed parison weighing 50 g, and then the parison was reheated to 105 to 110°C and biaxially stretched and blown. When a bottle with an internal volume of 1ρ was obtained, the preheating time during which the bottle could be blown without whitening was used as a measure of cloudiness. It is speculated that the crystals (flowing) that occur during injection molding become nuclei and crystallize during reheating, causing the bottle to become cloudy. The longer the preheating time, the less likely clouding will occur and the better the transparency.

Examples 1 to 6 and Comparative Examples 1 to 6 1,600 parts of dimethyl terephthalate (DMT), 1,020 parts of ethylene glycol, and an ethylene glycol solution of titanium trimellitate (1.0% by weight as titanium) 1
8 parts (3.5 mmol % based on DMT) were charged into a transesterification reactor, and the temperature was gradually raised from 150° C. to separate distilled methanol and carry out a transesterification reaction. The liquid temperature at the completion of the reaction was 230°C. Next, a predetermined amount of the phosphorus compound listed in Table 1 was added, the reaction product was transferred to a polycondensation mill, and an ethylene glycol slurry of germanium dioxide (1.15% by weight as germanium dioxide H8
, 7 parts <25 mmol% based on DMT), the mixture was reacted for about 10 minutes under normal pressure, and the reaction system was gradually reduced in pressure.
50mmt1g after 30 minutes, 20mmHg after 90 minutes,
0.5 mm) Ig after 120 minutes, while the internal temperature was 230
The temperature was gradually raised from ℃ to 280℃ after 120 minutes,
Thereafter, the polycondensation reaction was further carried out at this temperature for 1 hour, and then extracted from the polycondensation mill into running water by a conventional method to make chips. The intrinsic viscosity of this chip was 0.52. After pre-drying this chip at 160°C for 2 hours,
The temperature was raised to .degree. C., and solid phase polymerization was carried out under a reduced pressure of Q, 5 Torr in a nitrogen atmosphere for 6 hours to obtain a polymer with an intrinsic viscosity of 0.75. Table 1 shows the possible preheating time for bottles of this polymer without fogging.

Example 7 and Comparative Example 7 1600 parts dimethyl terephthalate (DMT), 1020 parts ethylene glycol, 1.77 parts ethylene glycol solution of titanium acetate (1.0% by weight as titanium)
4.5 mmol % based on MT) was charged into a transesterification reactor, and the transesterification reaction was carried out at 150 to 230°C. When the transesterification reaction was substantially completed, a predetermined amount of the phosphorus compound listed in Table 2 was added, the reaction product was transferred to a polycondensation mill, and 0.65 parts of antimony trioxide <27 mmol% based on DMT) was added. was added. The temperature of the indoor bath was raised to 290°C, and a high vacuum reaction was carried out for 190 minutes. The intrinsic viscosity of the obtained polymer was 0.64.

The high-speed spinning performance (limit spinning speed ability) of this polymer was as shown in the following table.

Table 2

Claims (1)

[Claims] 1) When producing polyester by a transesterification method using an organic titanium compound as a transesterification catalyst,
A method for producing polyester, characterized in that pentaerythritol diphosphite is used in an amount of 1.5 to 10 times the amount of the titanium compound by mole. 2) The method for producing a polyester according to claim 1, which comprises adding the pentaerythritol diphosphite at the time when the transesterification reaction is substantially completed. 3) The method for producing a polyester according to claim 1, wherein the pentaerythritol diphosphite is a bis(alkylphenyl) ester or a bisalkyl ester. 4) Alkylphenyl is (2,6-di-t-butyl-4
-methylphenyl).The method for producing a polyester according to claim 3. 5) The method for producing polyester according to claim 3, wherein the alkylphenyl is (2,4-di-t-butylphenyl). 6) The method for producing polyester according to claim 3, wherein the alkyl has 10 to 20 carbon atoms. 7) The method for producing polyester according to claim 3, wherein a distearyl phosphite is used. 8) A method for producing polyester, comprising using an organic titanium compound in an amount of 1 to 10 mmol % based on the total acid components of the polyester.