JPS5845452B2 - Manufacturing method of modified polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified polyester having good affinity for basic dyes.

More specifically, when producing polyester by the so-called direct loading method, which uses terephthalic acid and ethylene glycol as the main raw materials and performs an esterification reaction and a polycondensation reaction, the esterification rate is 90 or more, and the ethylene glycol component/ The molar ratio of terephthalic acid fraction is 1.1
At a stage of 1.6 or above, dimethyl 5-metal sulfoisophthalate in which 75% or more and 95% or less of the ester functional groups have been transesterified with ethylene glycol is added at a concentration of 25 to 45 and a pH of 5.0 to 7.5. The present invention relates to a method for producing a modified polyester, which is characterized in that the following ethylene glycol solution is added in an amount of 0.5 to 10 moles relative to terephthalic acid.

In general, polyester fibers have no affinity for basic dyes, so as shown in Japanese Patent Publication No. 34-10497, polyester fibers contain sulfonate groups in the form of metal salts and also contain carboxylic acid ester bond-forming groups. A method of increasing the affinity for basic dyes by copolymerizing compounds is known.

However, when applying this method to the straight weight method,
During the esterification and polycondensation reactions, a large amount of diethylene glycol is generated as a by-product and copolymerized into the main chain of the polyester, resulting in significant deterioration in the mechanical properties, heat stability, UV stability, and hydrolysis stability of the product. descend.

As a method for improving this, it is known to add alkali metal acetates, carbonate tertiary amines, etc. to the reaction system.

However, in the direct loading method, many low polymers with terminal carboxyl groups are present, so when alkali metal acetates or carbonates are added, they react to form insoluble substances, which causes a decrease in spinnability.

Furthermore, the addition of amines causes a significant decrease in the color tone of the product.

As a result of intensive research into methods for effectively suppressing the by-product of diethylene glycol and preventing the formation of insoluble substances and deterioration of color tone, the present inventor has determined the type and quality of the metal sulfonate group-containing compound to be added, and the addition of the compound. The present invention was developed based on the discovery that the method is important.

The metal sulfonate group-containing compound used in the present invention is
Transesterification of dimethyl 5-metal sulfoisophthalate with ethylene glycol resulted in a transesterification rate of 75%.
95% or less (hereinafter abbreviated as MSIE).

As the metal in MSIE, sodium, potassium, lithium, etc. are used, but sodium is most preferred.

MSIE is used in an ethylene glycol solution with a solid content concentration of 25% or more and 45% or less, preferably 35φ or more and 40% or less, and a pH of 5.0 or more and 7.5 or less, preferably 5.5 or more and 7.0 or less. .

The amount of MSIE added is 0.5 to 10 mol, preferably 1.5 to 5.0 mol, relative to terephthalic acid, the main raw material, and the timing of addition is between terephthalic acid and ethylene. Glycol esterification rate is 90φ
The above is preferably 95φ or more, and the molar ratio of ethylene glycol component/terephthalic acid component (hereinafter referred to as E-G/
TA molar ratio) is 1.1 or more and 1.6 or less, preferably 1.15. This is when the value is 1.35 or less.

If the transesterification rate of MSIE is less than 75%,
This is not preferable because the remaining carbomethoxy group may reduce the polymerization reaction rate or reduce the stability of the ethylene glycol solution, making it easier to form a precipitate.

Moreover, when the transesterification rate of MSIE is higher than 95%, the stability of the ethylene glycol solution becomes poor and a large amount of precipitate is deposited, which is not preferable.

The higher the concentration of MSIE in ethylene glycol solution,
Since the amount of free ethylene glycol in the reaction system decreases after addition, the amount of monomers distilled out of the system due to entrainment of droplets decreases, and the amount of diethylene glycol by-produced also decreases, which is preferable. This is not preferable because the stability of the ethylene glycol solution decreases.

Moreover, if the concentration is lower than 25%, it is not preferable because there is an increase in entrainment of heptomers after addition and an increase in the amount of diethylene glycol by-product.

If the pH of the MSIE ethylene glycol solution is lower than 5.0, the amount of diethylene glycol by-produced will increase, which is undesirable, while if the pH is higher than 7.5, coloring will easily occur, which is undesirable.

To adjust the pH, add hydroxides or weak acid salts of alkali metals or alkaline earth metals such as hydroxides, acetates, and carbonates of sodium, potassium, lithium, magnesium, and calcium to the MSIE ethylene glycol solution. It is preferable to do so.

It is also possible to add these metal compounds to the reaction system separately from the ethylene glycol solution of MSIB, but in that case, the amount of metal compounds added should be such that the pH of the ethylene glycol solution of MSIE is 5.0 or more and 7.5. It is necessary that the amount is suitable for the following, and that the addition time is substantially at the same time as or immediately before the addition of the ethylene glycol solution of MSIE.

If the amount of metal compound added is less than the amount required for pH adjustment, the amount of diethylene glycol by-product will increase, which is undesirable, and if it is too much, δ will cause discoloration or form insoluble substances, reducing spinnability. Therefore, it is undesirable.

If the time of addition of the metal compound is not substantially at the same time as or immediately before the addition of M'SIE, it is undesirable because insoluble substances may be formed or the amount of diethylene glycol by-product may increase.

If the amount of MSIE added is less than 0.5 mol φ relative to terephthalic acid, the affinity of basic dyes of polyester will not be sufficient, and if it is more than 10 mol φ, the excellent mechanical properties of polyester, which are the original characteristics of polyester, will not be sufficient. It is undesirable because it loses its properties and texture.

If the monomer esterification rate when adding the ethylene glycol solution of MSIE is lower than 90%, it is preferable because the amount of diethylene glycol by-product increases or insoluble substances are likely to be formed due to the influence of the remaining terminal carboxyl groups. do not have.

Furthermore, if the monomer's E G/T A1 molar ratio is lower than 1.1, the added MSIE will precipitate in the reaction system and form a sticky substance, which is undesirable; If it is large, the amount of diethylene glycol by-produced increases, which is undesirable.

The polyester used in the present invention is one that uses terephthalic acid and ethylene glycol as the main raw materials, and 70 or more moles of repeating structural units obtained by esterification reaction and polycondensation reaction consist of ethylene terephthalate, and a third component is also used. Carboxylic acids such as isophthalic acid, adipic acid, and sepatic acid, impropylene glycol, 1
．． Glycols such as 4-butanediol, neopentyl glycol, polyethylene glycol, monofunctional compounds such as monomethoxypolyethylene glycol and monobutoxypolypropylene glycol, or polyfunctional compounds such as pentaerythritol and trimellitic acid can be used.

It is also possible to add ultraviolet absorbers, heat-stable pigments, and the like.

As the catalyst used in the polycondensation reaction of polyester, compounds commonly used as polymerization catalysts, such as antimony trioxide, zinc acetate, and germanium dioxide, can be used.

Further, there are a batch method and a continuous method as a polyester manufacturing process, and either method is applicable.

Next, the present invention will be specifically explained with reference to Examples.

In the examples, all parts indicating the amount added mean parts by weight,
[η] is the intrinsic viscosity (unit: d///P) when polyester is dissolved in a mixed solvent of equal weights of phenol and tetrachloroethane and measured at 30°C. This value was determined by gas chromatography analysis after decomposition in a liquid, and represents the amount of diethylene glycol component copolymerized in the polyester (unit mole φ/polymer).

Also, white discoloration is 45% by Hitachi self-recording spectrophotometer EPR-2.
This is a value determined from the light separation ratio T450 and T55° of polyester fibers measured at wavelengths of 0 mμ and 550 mμ using the following formula, and the larger the value, the better the color tone.

Formula: Whitening (%) - 4T. -3T550MSIE's transesterification rate is a value determined by heating and hydrolyzing a sample in an aqueous sodium hydroxide solution and then performing gas chromatography analysis, and is the ratio of β-hydroxyethyl ester groups to all carboxylic acid ester groups in MSIE. is expressed as a percentage (unit: %).

The concentration of MSIE in ethylene glycol solution is the weight percentage determined by evaporating the sample to dryness.

In addition, the pH of the MSIE ethylene glycol solution is P
This is a value measured using an H meter HITACHI-HORIBA M-5 type.

The stability of MSIE's ethylene glycol solution is determined by placing a sample in a test tube, heating it in a water bath at 80°C to make it completely transparent, and then leaving it in a constant temperature room at 20°C until the precipitate begins to precipitate. Expressed in days.

The 7/mer composition upon addition of MSIE means the 7/mer composition immediately before addition of MSIE, and the esterification rate is the value determined by analyzing the terminal carboxyl group concentration in the monomer by neutralization titration.

The spinnability of polyester is as follows:
After passing through a 00 mesh filter, the diameter is 0.3
mvt, expressed as the time it takes for the pressure in front of the filter to reach 100 kg/C11t or more when extruding from a spinneret with 48 holes at a rate of 110 S' per minute and winding up and spinning at a speed of 800 m/min. .

Examples 1 to 6 and Comparative Examples 1 to 6 86 parts of pure terephthalic acid, 71 parts of ethylene glycol, 0.03 parts of antimony dioxide and 0.001 parts of phosphorous acid were placed in a batch reactor, and 2 kg was added at 270°G. /ci
After carrying out the esterification reaction at t-gauge pressure for 3 hours to remove main group water and excess ethylene glycol, dimethyl 5-sodium sulfoisophthalate having the quality shown in Table 1 was obtained. The product obtained by reacting with ethylene glycol (hereinafter abbreviated as SSIg) was added as an ethylene glycol solution in an amount of 2.5 mol to terephthalic acid. Then, pressure reduction was started and the pressure was reduced over 60 minutes. 1.5 mmH? After reaching , [η] becomes 0.45dt/? The resulting polymer was extruded in the form of a strand, and then made into chips using a granulator.

After thoroughly drying this chip, it was melt-spun and the spinnability was evaluated.

These results are shown in Table 1. Examples 7 to 9 and Comparative Examples 7 to 9 86 parts of pure terephthalic acid, 71 parts of ethylene glycol, 3 parts of titanium dioxide, 0.03 part of antimony trioxide and 0.001 part of phosphorous acid were placed in a patch reactor, 270℃
The esterification reaction was carried out at a pressure of 2 kg/air gauge, and the produced water and excess ethylene glycol were distilled off to obtain monomers having the composition shown in Table 2, and the transesterification rate was 80%. PH6.1, concentration 41φ
Add 2.5 mol of ethylene glycol solution of 5SIE to terephthalic acid, then start depressurizing and reduce the pressure to 1.5 vunH in 60 minutes. After reaching , [η] becomes 0.45 di/? The polycondensation reaction was carried out until reaching the desired temperature, and the resulting polymer was extruded in the form of a strand, and then made into chips using a granulator.

After thoroughly drying this, it was melt-spun and the spinnability was evaluated.

These results are shown in Table 2. Example 3 and Comparative Examples 10 to 12 Two completely mixed esterification tanks (first ES tank and second ES tank)
ES tank), initial polymerization tank (PP tank), and final polymerization tank (P
Modified polyesters were produced by copolymerizing 2.0 mol φ of 5SIE with terephthalic acid under various conditions using a 4-tank serial type continuous reactor (P tank).

The reaction temperature and pressure of the first BS tank and second ES tank are 2
70° C. 12, Oky/crA gauge pressure, and residence times are 120 and 90 minutes, respectively.

The temperature of the PP tank is 270℃ and the pressure is 12H. and the residence time I/'i is 60 minutes.

The F"P tank has a temperature of 280°C and a pressure of 0.8 mmHS', and the residence time of the polymer [η] is 0.42 di/fl.
Until it reached .

The composition of the raw materials charged into the first E'S tank is 83 parts of terephthalic acid, 62 parts of ethylene glycol, and 0.0 parts of antimony trioxide.
3 parts and 1 part titanium dioxide.

5SIEJj: The transesterification rate was 83 and the pH 6.2 concentration was 38%.

The resulting linked polymer was directly sent to a spinning machine, spun under the conditions described in the text, and the spinnability was determined.

Claims (1)

[Claims] 1 Main raw materials are terephthalic acid and ethylene glycol,
When producing polyester by an esterification reaction and a subsequent polycondensation reaction, at a stage where the esterification rate of the monomer is 90% or more and the molar ratio of ethylene glycol component/terephthalic acid fraction is 1.1 or more and 1.6 or less. , dimethyl 5-metal sulfoisophthalate in which 75% to 95% of the ester functional groups have been transesterified with ethylene glycol at a concentration of 25 to 45%, PH5,
A method for producing a modified polyester, characterized in that an ethylene glycol solution of 0 or more and 7.5 or less is added in an amount of 0.5 to 10 moles φ to terephthalic acid.