JPH11302365A - Production of polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polytrimethylene terephthalate capable of remarkably reducing by-products such as allyl alcohol or acrolein, having excellent dyeability for a cationic dye and excellent in whiteness degree. SOLUTION: A polytrimethylene terephthalate is prepared as a master polyester and the resultant polytrimethylene terephthalate and (1) a prepolyester of a polyethylene terephthalate, a polytrimethylene terephthalate or a polybutylene terephthalate copolymerized with 0.5-50 mol.% of an ester-forming sulfonic salt compound or (2) the ester-forming sulfonic ester compound are separately charged into an extruder or premixed and then charged into the extruder so that the finally obtained polyester contains 0.5-5 mol.% of the ester-forming sulfonic salt unit based on the trimethylene terephthalate unit. The transesterification is then carried out in the extruder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polymerizing a polyester. More specifically, the present invention relates to a method for producing polytrimethylene terephthalate, which can significantly reduce by-products of allyl alcohol and acrolein, have excellent dyeing properties for cationic dyes, and have excellent whiteness.

[0002]

2. Description of the Related Art Polytrimethylene terephthalate obtained by polycondensing a lower alcohol ester of terephthalic acid represented by terephthalic acid or dimethyl terephthalate with trimethylene glycol (1,3-propanediol) has low elasticity. Properties similar to polyamide such as rate (soft texture), excellent elastic recovery, easy dyeing,
It is an epoch-making polymer that has properties similar to polyethylene terephthalate, such as light resistance, heat setting, dimensional stability, and low water absorption, and is applied to carpets, brushes, tennis gut, etc. by taking advantage of its characteristics ( JP-A-9-3724, JP-A-8-173244,
JP-A-5-262882).

[0003] Polytrimethylene terephthalate is copolymerized with an ester-forming sulfonate compound and melt-spun to obtain a polytrimethylene terephthalate fiber having a characteristic characteristic of the above-mentioned polytrimethylene terephthalate fiber and a dye capable of being dyed with a cationic dye. The present inventors have already found that methylene terephthalate fibers can be obtained (Japanese Patent Application No. 9-2453).
No. 01). However, when an ester-forming sulfonate compound represented by dimethyl 5-sodium sulfoisophthalate is copolymerized with polytrimethylene terephthalate, there is a problem that many by-products are generated in the working environment and the recovery step. there were.

When the above copolymerized polytrimethylene terephthalate is polymerized, a lower alkyl ester of terephthalic acid such as terephthalic acid or dimethyl terephthalate, 1,3-propanediol, and an ester-forming sulfonate compound are converted to titanium alkoxide, acetic acid, or the like. calcium,
The oligomer is once produced by reacting in the presence of a catalyst such as manganese acetate, and then, if necessary, a catalyst such as titanium alkoxy oxide or antimony trioxide is added for polymerization. At this time, part of the 1,3-propanediol undergoes a dehydration reaction and a reduction reaction to produce allyl alcohol and acrolein. These by-products have been found to be highly toxic and to be easily vaporized due to their low boiling point, and to leak out of the facility at all stages of the polymerization process.

[0005] In particular, acrolein has a high tearing property, and its odor is unbearable even at about 0.1 ppm. Therefore, a large amount of capital investment is required to treat it or completely remove it from production equipment. Become. These by-products are also produced at the stage of polymerization of polytrimethylene terephthalate homopolymer, but when copolymerizing an ester-forming sulfonate compound, the production amount is considerably large, so measures have been required. . Further, when copolymerizing an ester-forming sulfonate compound with polytrimethylene terephthalate, the heat resistance of the polymer is reduced,
It sometimes became yellowish during the polymerization. When fibers are made from a yellowed polymer, there is a practical problem such as poor coloring when dyed lightly.

[0006]

The present invention can greatly reduce by-products such as allyl alcohol and acrolein,
An object of the present invention is to provide a method for producing polytrimethylene terephthalate, which has excellent dyeability for a cationic dye and has excellent whiteness.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have described a method for copolymerizing an ester-forming sulfonate compound with polytrimethylene terephthalate by using known batch polymerization and continuous polymerization. However, these methods could not solve the problem, and a prepolymer or ester-forming sulfonic acid obtained by copolymerizing a large amount of an ester-forming sulfonic acid compound with polytrimethylene terephthalate in an extruder having high stirring efficiency was examined. The possibility that the target copolymerized polytrimethylene terephthalate can be produced in a short reaction time by reactive processing of the salt compound was found, and as a result of further studies, the present invention was reached.

That is, the present invention provides a polyethylene terephthalate and a polytrimethylene terephthalate prepared by preparing polytrimethylene terephthalate as a master polyester and copolymerizing the master polyester with (1) an ester-forming sulfonate compound in an amount of 0.5 to 50 mol%. Prepolyester of methylene terephthalate or polybutylene terephthalate,
Or (2) the ester-forming sulphonate compounds are separately or pre-treated such that the finally obtained polyester contains 0.5 to 5 mol% of ester-forming sulphonate units per trimethylene terephthalate unit. This is a method for producing a polyester, which comprises mixing, introducing the mixture into an extruder, and subjecting the mixture to transesterification in the extruder.

In the present invention, the master polyester is substantially polytrimethylene terephthalate.
Polytrimethylene terephthalate is a polycondensate of 1,3-propanediol and a lower ester of terephthalic acid such as terephthalic acid or dimethyl terephthalate. Here, "substantially" means that 5% by weight or less of an ester-binding comonomer may be copolymerized with polytrimethylene terephthalate. Such comonomers include isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dodecanoic acid, dodecandioic acid, cyclohexanedicarboxylic acid, ethylene glycol, butanediol , Hexanediol, cyclohexanediol, cyclohexanedimethanol, trimethylene glycol dimer, and one or more combinations of polyalkylene glycol having an average molecular weight of 400 to 20,000.

The intrinsic viscosity [η] of polytrimethylene terephthalate is 0.4 to 2.0, preferably 0.5 to 1.
5, more preferably in the range of 0.6 to 1.2. Within this range, a fiber having excellent strength and spinnability can be obtained. When the intrinsic viscosity is less than 0.4, spinning becomes unstable because the melt viscosity of the polymer is too low, and the strength of the obtained fiber is low and is not satisfactory. Conversely, if the intrinsic viscosity exceeds 2.0, the melt viscosity is too high, and melt fracture or poor spinning occurs during spinning.

The ester-forming sulfonate compound used in the above (1) and (2) of the present invention has one or two carboxylic acids or lower esters of carboxylic acids in one molecule of the monomer, and further has at least one Is a compound having two sulfonates. Specific examples include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid,
Lithium sulfoisophthalic acid, tetrabutylphosphonium 5-sulfoisophthalate, tributylbenzylphosphonium 5-sulfoisophthalate, 4-sodium sulfo-2,6-naphthalenedicarboxylic acid, 4-sodium sulfobenzoic acid and the like. May be methyl and ethyl esters.

The prepolyester is polyethylene terephthalate, polytrimethylene terephthalate or polybutylene terephthalate obtained by copolymerizing the ester-forming sulfonate compound in an amount of 0.5 to 50 mol%. The copolymerization ratio is 0.5 to 50 mol%, and if it is less than 0.5 mol%, it cannot be dyed with a cationic dye in a deep color,
If it exceeds 50 mol%, the polymerization reaction becomes extremely difficult to proceed. From these balances, preferably 5 to 50 mol%,
More preferably, it is 10 to 40 mol%. The intrinsic viscosity [η] of these master polyesters is not particularly limited, but is preferably in the range of 0.1 to 1.0 from the viewpoint of good reactivity in the extruder.

Various additives such as matting agents, heat stabilizers, defoaming agents, tinting agents, flame retardants, antioxidants, ultraviolet absorbers, and infrared absorbers are included in the master polyester and prepolyester. , Crystal nucleating agent, copolymerization of fluorescent whitening agent, etc.,
Alternatively, they may be mixed. Especially in the prepolyester,
Lithium acetate, lithium carbonate, sodium hydroxide, potassium hydroxide and the like are used in an amount of 0.1 to 20 with respect to the ester-forming sulfonate compound in order to reduce the amount of foreign matter that does not melt.
Mol%, preferably 1 to 10 mol%.

In order to improve heat resistance, ammonium salts such as tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide and tetrapropylammonium hydroxide, chlorobenzylphosphonium chloride, stearylethyldihydroxyethylphosphonium Ethosulfate, tetrabutylphosphonium acetate, tetrabutylphosphonium dodecylbenzenesulfonate, tetrabutylphosphonium tosylate, tetrabutylphosphonium oleate, tetrabutylphosphonium phosphate, tetrabutylphosphonium phosphite, tetrabutylphosphonium phosphite, etc. It is preferable to add 0.1 to 20 mol% to the sulfonate compound, and it is particularly preferable to add 0.1 to 20 mol%. Properly it is added 1-10 mol%.

In the present invention, the prepolyester is synthesized by any method. For example, in the case of polyethylene terephthalate, terephthalic acid and ethylene glycol are directly reacted or reacted with a lower alkyl ester such as dimethyl terephthalate to form a terephthalic acid glycol ester and / or a low polymer thereof. It is produced by a one-stage reaction and a second-stage reaction in which a reaction product of the first stage is subjected to a polycondensation reaction by heating under reduced pressure in the presence of a polymerization catalyst to a desired degree of polymerization. In this case, the ester-forming sulfonate compound or the additive as the copolymer component can be added at any stage, and may be added at once or in several portions.

According to the present invention, a prepolyester or an ester-forming sulfonate compound is mixed with a master polyester, and the ester-forming sulfonate compound in the finally obtained polyester is 0.5 to 5 mol per trimethylene terephthalate unit. % Range
This is a method in which polytrimethylene terephthalate in which an ester-forming sulfonate compound is copolymerized is charged separately or beforehand into an extruder and transesterified in the extruder.

As a method for feeding the raw materials to the extruder, when a master polyester and a prepolyester are used, both may be formed into chips and mixed separately or in advance.
One of them may be added in a molten state. When the master polyester and the ester-forming sulfonate compound are used, they may be mixed separately or in advance, or the master polyester may be melted and the ester-forming sulfonate compound may be added thereto. In the latter case, in order to improve the weighability, a part of the powdered master polyester may be mixed with the ester-forming sulfonate compound and introduced into the extruder.

In addition, when adding raw materials, matting agents, heat stabilizers, defoamers, tinting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent brighteners, etc. Separately
Alternatively, they may be added at the same time, and particularly when an ester-forming sulfonate compound is used, mixing an additive preferably added to the prepolyester to reduce the amount of foreign substances or an additive to improve heat resistance can improve the spinnability and the whiteness. This is a preferred method from the viewpoint of improving the degree.

In the present invention, the extruder is not particularly limited, but it is preferable to use a screw-type twin-screw extruder because the kneading performance is high and the reaction can be completed in a short time. The temperature of the extruder is 10 to 4 from the melting point of the polymer used.
0 ° C. higher, preferably 2 ° C. above the melting point of the polymer used.
0 to 40 ° C. higher temperature.

The reaction pressure should be reduced under reduced pressure using a vacuum pump, usually 50 torr or less, preferably 10 or less, more preferably 1 torr or less, and water, methanol, etc. generated as the polycondensation reaction proceeds. It is preferable to distill off the alcohol or by-products such as allyl alcohol and acrolein which are produced in a very small amount.
The reaction time is preferably 1 to 60 minutes, particularly preferably 5 to 30 minutes. Usually, the polycondensation reaction takes about 90 to 250 minutes, but by using the present invention, the reaction can be completed in such a short reaction time. As a result, by-products can be drastically reduced, and at the same time, a polymer having excellent whiteness can be obtained. The number of rotations of the screw of the extruder is 20 to 5
00 rpm is desirable, and preferably 50 to 300 rpm
It is. When a twin-screw extruder is used, the directions of rotation of the two axes may be the same or opposite, but rotation in the same direction is preferable from the viewpoint of suppressing thermal deterioration.

The polytrimethylene terephthalate finally obtained has a copolymer of an ester-forming sulfonate compound in an amount of 0.5 to 5 mol% per trimethylene terephthalate unit. It is necessary to show sufficient dyeability. If the copolymerization ratio is less than 0.5 mol%, it cannot be dyed in a deep color, and if it exceeds 5 mol%, it will be dyed in a dark color, but the hydrolysis resistance, yellowing resistance and strength will be reduced. Preferably,
From these balances, it is in the range of 1.5 to 3 mol%, more preferably 1.7 to 2.5 mol%. The polymer discharged from the extruder may be subjected to a cooling step such as a water cooling bath and formed into chips using a chip cutter, or may be directly connected to a spinning machine.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples and the like, but needless to say, the present invention is not limited to the examples and the like. The main measured values in the examples were measured by the following methods. (1) Intrinsic Viscosity This intrinsic viscosity [η] is a value determined based on the following definition formula. Ηr in the definition formula is a value obtained by dividing the viscosity at 35 ° C. of a diluted solution of a polyester polymer dissolved in o-chlorophenol having a purity of 98% or more by the viscosity of the solvent itself measured at the same temperature, and It is defined.
C is the solute weight value in grams in 100 ml of the solution.

(2) Strength, elongation, modulus of elasticity Tensilon manufactured by Orientec Co., Ltd., yarn length 20 c
m and the tensile speed were 20 cm / min.
Further, the elastic modulus is such that the elongation of the yarn during the tensile test is 0.5%.
Average values between ２2 mm were used.

(3) Exhaustion Rate of Cationic Dye The sample was a single-knit knitted fabric, and score roll 400 was used.
The scouring treatment was performed at 70 ° C. for 20 minutes using warm water containing g / liter, dried by a tumbler drier, and then heat-set at 180 ° C. for 30 seconds using a pin tenter. The exhaustion rate was obtained by raising the temperature from 40 ° C. to 110 ° C., and further holding the same for 1 hour, and measuring the exhaustion rate according to the following equation. The dye is Kayakuriru Blue GSL
Using -ED (manufactured by Nippon Kayaku Co., Ltd.), staining was carried out at 4% owf at a bath ratio of 1:50. Exhaustion rate = 100 × amount of dye absorbed by fiber / amount of dye in dye bath

[0025]

Example 1 146 parts of dimethyl terephthalate, 1,3
-Mix 175 parts of propanediol, 89 parts of dimethyl 5-sodium sulfoisophthalate, 14 parts of titanium tetrabutoxide and 30 parts of lithium acetate dihydrate,
The transesterification reaction was terminated at 0 ° C.
Under a reduced pressure of 0.2 torr and a polymerization time of 30 minutes, a polytrimethylene terephthalate prepolymer was obtained by copolymerizing 30 mol% of dimethyl 5-sodium sulfoisophthalate having an intrinsic viscosity of 0.2 under a reduced pressure of 0.2 torr. The amount of acrolein by-produced during the polymerization was determined from the distilled methanol and 1,3-propanediol.
0.1% of 3-propanediol.

Using a twin-screw extruder equipped with two weight feeders, polytrimethylene terephthalate having an intrinsic viscosity of 0.9 was supplied while being metered by a weight feeder, and 265 ° C.
And the prepolymer was fed into the extruder from another weight feeder. The feed was set so that the copolymerization ratio of the final polymer was 2.3 mol%. After the two kinds of supplied polymers were mixed, the pressure was reduced at a pressure of 0.2 torr from a vent port provided in the extruder. The residence time was 15 minutes and the number of revolutions was 100 rpm. After the reaction, the polymer is extruded into strands,
After being solidified in a water-cooled bath, it was chipped with a chip cutter.

The obtained polymer was obtained by copolymerizing 2.3 mol% of dimethyl 5-sodium sulfoisophthalate, was excellent in whiteness, and had an intrinsic viscosity of 0.7. When 30 kg of this copolymer was produced, the total amount of acrolein and allyl alcohol present in the trap of the vacuum pump provided in the extruder was 120 ppm based on 1,3-propanediol used.

Using the obtained chips, melt spinning is performed at 260 ° C. and a spinning speed of 2000 m / min, preheated at 55 ° C., stretched while heat setting at 160 ° C.
36f fibers were obtained. The obtained fiber has a strength of 3.5 g /
d, elongation 30%, elastic modulus 25%, soft touch. Further, when dyed with a cationic dye, the exhaustion rate was 74% and a vivid color was exhibited.

[0029]

Example 2 Example 1 was repeated except that polyethylene terephthalate obtained by copolymerizing 30% by mole of dimethyl 5-sodium sulfoisophthalate was used as the prepolymer. The obtained polymer was excellent in whiteness and copolymerized with 2 mol% of dimethyl 5-sodium sulfoisophthalate, and had an intrinsic viscosity of 0.74. When 30 kg of this copolymer was produced, the total amount of acrolein and allyl alcohol present in the trap of the vacuum pump provided in the extruder was 42 p with respect to 1,3-propanediol used.
pm.

[0030]

Example 3 Example 1 was repeated except that polybutylene terephthalate obtained by copolymerizing 30 mol% of dimethyl 5-sodium sulfoisophthalate was used as the prepolymer. The obtained polymer was excellent in whiteness and copolymerized with 2 mol% of dimethyl 5-sodium sulfoisophthalate, and had an intrinsic viscosity of 0.78. When 30 kg of this copolymer was produced, the total amount of acrolein and allyl alcohol present in the trap of the vacuum pump provided in the extruder was 24 p with respect to 1,3-propanediol used.
pm.

[0031]

Example 4 Example 1 was repeated except that the powder obtained by mixing equimolar amounts of dimethyl 5-sodium isophthalate and lithium acetate dihydrate in the same manner as in Example 1 was used instead of the prepolymer. The obtained polymer was excellent in whiteness and copolymerized with 2.3 mol% of dimethyl 5-sodium sulfoisophthalate, and had an intrinsic viscosity of 0.65.
When 30 kg of this copolymer was produced, the total amount of acrolein and allyl alcohol present in the trap of the vacuum pump provided in the extruder was 220 pp with respect to 1,3-propanediol in polytrimethylene terephthalate.
m.

Using the obtained chips, melt spinning was performed at 260 ° C. and a spinning speed of 2000 m / min, and the film was preheated at 55 ° C. and stretched while heat setting at 160 ° C.
6f fibers were obtained. The obtained fiber has a strength of 3.1 g / d,
The elongation was 32% and the elastic modulus was 25%, and the feel was soft. When dyed with a cationic dye, the exhaustion rate was 70%.
% And bright color development.

[0033]

Comparative Example 1 188 parts of dimethyl terephthalate, 1,3
-175 parts of propanediol, 8.9 parts of dimethyl 5-sodium sulfoisophthalate, 14 parts of titanium tetrabutoxide and 3 parts of lithium acetate dihydrate were mixed, and 22
The transesterification reaction was terminated at 0 ° C.
Under a reduced pressure of 0.2 torr and a polymerization time of 150 minutes, a polytrimethylene terephthalate prepolymer obtained by copolymerizing 3 mol% of dimethyl 5-sodium sulfoisophthalate having an intrinsic viscosity of 0.6 was obtained under a reduced pressure of 0.2 torr. The amount of acrolein by-produced during the polymerization was determined from the distilled methanol and 1,3-propanediol.
0.4% of 3-propanediol was higher than that of the examples. Further, the polymer was slightly yellowish.

[0034]

According to the present invention, there is provided a twin-screw extruder having a reaction efficiency which is extremely high in a monomer which is a polyester dyeing a polyester or a cationic dye dyeing a large amount of a dyeing seat dyeing a polytrimethylene terephthalate and a cationic dye. In a short time in order to provide polytrimethylene terephthalate which dyes a cationic dye. By using the present invention, by-products of allyl alcohol and acrolein can be significantly reduced as compared with a case where the same copolymerized polytrimethylene terephthalate is polymerized in a polymerization vessel, and the whiteness is also excellent because the reaction time is short. A polymer was obtained.

Claims (1)

[Claims] 1. Polytrimethylene terephthalate is prepared as a master polyester, and the master polyester and (1) an ester-forming sulfonate compound are added in an amount of 0.5%.
~ 50 mol% copolymerized polyethylene terephthalate,
A pre-polyester of polytrimethylene terephthalate or polybutylene terephthalate, or (2) an ester-forming sulfonate compound, may be used in an amount of 0.1% per trimethylene terephthalate unit.
A process for producing a polyester, characterized in that the mixture is charged into an extruder separately or premixed so as to contain 5 to 5 mol% of an ester-forming sulfonate unit, and transesterified in the extruder.