CN1260269C - Modified polyester and its continuous production method - Google Patents

Abstract

The present invention provides a modified polyester, the main repeating unit is terephthalic acid glycol ester, in the acid component containing 2.0 ~ 3.0 mol% containing metal sulfonate group between benzene two formic acid components, in the polymer containing 9.0 ~ 13.0 weight% average molecular weight 1000 ~ 10000 polyalkylene glycol, characterized in that: in the ethylene glycol component, DEG is contained in a molar percentage of 4.7 to 5.7 mol%, and the maximum value [ eta ] of the limiting viscosity]_maxAnd minimum value [ eta ]]_minThe ratio of the first to the second is 1.0 to 1.02. The modified polyester has sufficient alkali water solubility, low viscosity and no coloring during melt spinning, and has excellent spinning operability and production performance.

Description

Modified polyester and its continuous production method

technical field

The present invention relates to modified polyester which is very easily soluble in alkaline water and its continuous production method. In particular, it relates to an alkali soluble polyester with stable limit viscosity, spinning operability and silk physical properties, and a direct continuous polymerization production method of the alkali soluble polyester with high efficiency and low production cost.

Background technique

Alkali-soluble polyester is used as a constituent of a split-type conjugate fiber in which one component A is divided into a plurality of other components B. In terms of composite fibers, for example, disclosed in Japanese Patent Publication No. 63-20939 and Japanese Patent Publication No. 8-14042, it dissolves at least a part of the split components by alkali treatment, and uses them as split yarns to obtain extremely fine deniers. It is a composite fiber manufactured for the purpose of ultra-fine filaments. This composite fiber is used to manufacture high-density woven fabrics with a crisp style or silk-like woven fabrics with elegant luster and soft touch.

In addition, conjugate fibers are used as constituents of polyester-based fabrics suitable for so-called bleaching, for example, the fabrics described in JP-A-4-91894.

In the past, various studies have been carried out on alkali-soluble polyesters. For example, in JP-A-47-47532, polyethylene terephthalate added with 5 to 16% by weight of polyalkylene glycols has been proposed. In addition, JP-A-63-20939 proposes polyethylene terephthalate copolymerized with 3 mol% or more of 5-sodiumsulfonate-isophthalate.

However, in the former case, if the content of polyalkylene glycols is high, the heat resistance and air oxidation resistance of the polymer will deteriorate, the viscosity will decrease during melt spinning, and coloring, adding Problems such as pulverization in the twisting process. And, with respect to the latter situation, if the copolymerization rate of 5-sodium sulfonate base-isophthalate is more, just exist because 5-sodium sulfonate base-isophthalate holds charge Coagulation, gelation and viscosity increase, making spinning difficult, and due to the generation of fine gel, the spinning filtration pressure rises sharply, and the spinning operability deteriorates.

Therefore, in Japanese Patent Publication No. 61-1551 and Japanese Patent Laid-Open Publication No. 1-162825, it is proposed to use the two components after proper adjustment, but the current situation is that the above-mentioned problems cannot be completely solved.

Now, the mainstream of the method for producing modified polyester is the transesterification method using dimethyl terephthalate (hereinafter referred to as the DMT method) described in JP-A-62-89725. In the DMT method, generally batch method. In addition, as a production method related to a direct polymerization method (hereinafter referred to as direct polymerization method) using terephthalic acid, it is described in JP-A-58-45971, but this is also a batch method. If the batch method is used, there will be the following problems: due to the aging change of polymer extrusion, the polymer viscosity at the beginning of extrusion and the polymer viscosity at the end of extrusion will be different, and if the number of batches is increased, the tank The polymer remaining in the batch is mixed with degraded foreign matter, which increases the difference in the physical properties of the polymer between batches. The countermeasure to improve these problems is to reduce the number of batches and blend polymer particles, but the production efficiency is low, and low-cost production cannot be carried out.

As a countermeasure against the above, for example, Japanese Unexamined Patent Publication No. 62-146921 proposes to use a direct continuous polymerization method, extract oligomers after esterification, and introduce them into a separate polymerization tank for production by batch polymerization. The polymerization reaction is changed to a batch mode, and there are also problems of uneven physical properties of the polymer, inability to meet needs, and complicated equipment.

Contents of the invention

In order to solve the disadvantages of the prior art, the object of the present invention is to provide a modified polyester having sufficient alkali water solubility, reduced viscosity and less coloring during melt spinning, excellent textile operability, and excellent production performance.

In order to achieve the above object, the present invention provides a main repeating unit is ethylene terephthalate, containing 2.0 to 3.0 mole % of isophthalic acid components containing sulfonic acid metal salt groups in the acid component, in the polymer A polyester containing 9.0 to 13.0% by weight of polyalkylene glycol with an average molecular weight of 1,000 to 10,000, characterized in that: in the ethylene glycol component, the molar percentage of DEG contained is 4.7 to 5.7 mole%, The ratio of the maximum value [η] _max and the minimum value [η] _min of the intrinsic viscosity of the polyester is: 1.0≤[η] _max /[η] _min≤1.02 .

And, the production method of polyester of the present invention is characterized in that: use terephthalic acid, ethylene glycol, the isophthalic acid component that contains sulfonic acid metal salt group, polyalkylene glycol as raw material, carry out direct esterification When producing polyester by reaction and condensation reaction, 2.0 to 3.0 mol% of isophthalic acid components containing sulfonic acid metal salt groups are contained in the acid component, and the dicarboxylic acid component and ethylene glycol are slurried, and the pH is adjusted to 4.5 to 5.5, under the condition that the total molar ratio of ethylene glycol/dicarboxylic acid components is 1.1 to 1.2, the slurry is subjected to a continuous esterification reaction, and the resulting oligomer is added to the polymer. After that, 9.0 to 13.0% by weight of polyalkylene glycol is sequentially introduced into a polymerization tank, and a series of reactions such as polymerization reaction are carried out continuously under reduced pressure.

The alkali easily soluble modified polyester of the present invention has excellent operability under conditions close to that of ordinary polyethylene terephthalate because of its fast dissolution rate in alkaline solvents, and can be melt-spun and post-treated. , so it can be efficiently used in the production of composite fibers for ultrafine yarn production and fabrics for bleaching processing.

Description of drawings

Fig. 1 is a schematic diagram showing the steps of the production method of the present invention.

Explanation of symbols: 1 slurry tank; 2 first esterification tank; 3 second esterification tank; 4 polymerization tank;

Detailed ways

The present invention will be described in detail below. The isophthalic acid component containing sulfonic acid metal base used in the present invention adopts 5-sulfonic acid metal base-dimethyl isophthalate (hereinafter referred to as SIPM) or performs esterification with ethylene glycol and dimethyl ester. The exchanged compound (hereinafter referred to as SIPE). If too much SIPM is put into the slurry tank, the physical properties of the slurry will deteriorate, so SIPE is preferred. As the metal in SIPM or SIPE, sodium, potassium, lithium, etc. can be used, but sodium is most preferred.

The copolymerization ratio of SIPE needs to be set to 2.0 to 3.0 mol% in the acid component of the polymer. If the copolymerization rate of SIPE is less than this, sufficient alkali solubility cannot be obtained. On the other hand, if the copolymerization rate is higher than this, thickening and gelation will occur due to the charge action of SIPE in the melt spinning process, and the handleability will be significantly reduced.

And, polyalkylene glycol can be represented by the general formula HO(C _n H _2n O) _m H (where n, m are positive integers), and polyethylene glycol (hereinafter referred to as PEG) when n=2 is Widely used and ideal.

The molecular weight of PEG used in the present invention needs to be 1,000 to 10,000. If the molecular weight is less than 1000, the hydrolysis reaction of the modified polyester is likely to occur during melt spinning, and the heat resistance of the polyester is insufficient, and adhesion between polyester particles occurs, and pulverization occurs in the twisting process. Also, if the molecular weight exceeds 10,000, polymerization reactivity is lacking, and since it is difficult to copolymerize PEG into a molecular chain of polyester, the oxidation resistance of polyester deteriorates.

The copolymerization amount of PEG needs to be 9.0 to 13.0% by weight of the polymer. If the amount of copolymerization is less than 9.0% by weight, the alkali water solubility will be insufficient. On the other hand, if it exceeds 13.0% by weight, the heat resistance and oxidation resistance of the polymer will deteriorate.

The ratio of the maximum value [η] _max and the minimum value [η] _min of the intrinsic viscosity of the polyester of the present invention is: 1.0≤[η] _max /[η] _min≤1.02 . If [η] _max / [η] _min is outside the above range, yarn breakage will often occur during spinning, and the life of the spinning die will be shortened due to the deterioration of spinning filterability, and the workability will deteriorate.

Furthermore, the polyester of the present invention contains 4.7 to 5.7 mol% of diethylene glycol (DEG) in the ethylene glycol component. This DEG is produced by side reactions during polymerization. If it is less than 4.7 mol%, the alkali water solubility will deteriorate. Moreover, if it exceeds 5.7 mol%, the heat resistance and oxidation resistance of a polymer will deteriorate, and the handleability at the time of melt spinning will deteriorate significantly.

The method for producing the modified polyester according to claim 2 of the present invention will be described in detail below with reference to the accompanying drawings. (FIG. 1) is a schematic diagram showing steps of an embodiment of the present invention. After the terephthalic acid and ethylene glycol are slurried in the slurrying tank 1, the isophthalic acid compound containing a sulfonic acid metal salt group is put into 1 from the inlet a and slurried. Then, this slurry is continuously supplied to the 1st esterification tank 2, and it performs esterification reaction and forms an oligomer. Then, the generated oligomers are sequentially supplied to the second esterification tank 3, and polyalkylene glycol is added to the inlet b. Then, this oligomer is sequentially and continuously supplied to the polymerization tank 4, and the polymerization reaction is continuously performed to a predetermined degree of polymerization in a vacuum state. The polymer having reached a given degree of polymerization is extruded from the polymer outlet (not shown) of the polymerization tank 4 through fine holes into a cooling water bath, and the extruded strands are pelletized by a cutting device.

Here, it is important to uniformly add the isophthalic acid component containing a metal sulfonic acid group to the previously prepared slurry of terephthalic acid and ethylene glycol. According to conventional technical ideas, in order to suppress the gel caused by the charge of SIPE, SIPE is generally added to an oligomer with a low acid value. However, since the esterified oligomer has a high viscosity, there is a problem that the dispersibility of SIPE deteriorates and aggregation occurs. Furthermore, the depolymerization method in which ethylene glycol is added to the esterified oligomer to lower the degree of polymerization is only applicable to a batch-type production method. As in the present invention, by uniformly charging and dispersing SIPE in a slurry of terephthalic acid and ethylene glycol, the above-mentioned problems can be solved, and an efficient continuous polymerization method can be employed.

In this way, it is also necessary to add hydroxides of sodium, potassium, lithium, magnesium, calcium, etc., hydroxides of alkali metals or alkaline earth metals such as carbonates, and weak acid salts to the prepared slurry. , adjust the pH value of the slurry to within the range of 4.5-5.5. Specifically, the compound added for pH adjustment includes sodium acetate, potassium acetate, lithium acetate, sodium hydroxide, potassium hydroxide, etc., but sodium acetate, lithium acetate, etc. are particularly useful. There is no particular method of adding these compounds, but, for example, an addition method of dissolving them in a small amount of ethylene glycol is suitable.

If the pH value of the slurry is less than 4.5, there will be a lot of side reactions of DEG. On the other hand, if the pH exceeds 5.5, the color of the polymer is increased, and a lot of insoluble matter is generated in the polymer, so that a polymer suitable for practical use cannot be obtained. The pH value is preferably in the range of 4.7 to 5.3.

In the present invention, it is necessary to set the total molar ratio of ethylene glycol/dicarboxylic acid components at the time of esterification to 1.1 to 1.2. If the molar ratio exceeds 1.2, a large amount of DEG will be generated, impairing the physical properties of the polymer. And if it is less than 1.1, since the amount of ethylene glycol is insufficient, esterification reaction and polymerization reaction cannot be performed normally.

The input of PEG is preferably carried out in b of FIG. 1 , in the first esterification tank 2 . The input standard is that the esterification rate of the oligomer is above 80%. If the esterification rate is above 80%, even if the boiling phenomenon occurs due to the input of PEG, the amount of free ethylene glycol is very small, so the foaming phenomenon in the system can be suppressed.

For the purpose of improving various physical properties, a light-resistant agent, a heat-resistant agent, a matting agent, and the like may be added to the polyester of the present invention. The addition of these additives may be performed in any process in the production process.

Example

Next, the present invention will be described in more detail by way of examples. In addition, the characteristic values of the following examples were measured by the method shown below.

(1) Intrinsic viscosity [η]

Sample collection for the measurement of the intrinsic viscosity [η] of the polymer particles was performed as follows. In the case of polymers produced using continuous polymerization methods, collect pellets at appropriate time intervals and use them as samples, and in the case of polymers produced using batch-type polymerization methods, for each batch of polymer starting extrusion and Aggregated pellets immediately after extrusion, and suitable aggregated pellets in the middle of extrusion are collected as samples. In a mixed solvent of phenol/tetrachloroethane=6/4 (weight ratio), the sample was measured by the Ubbel-Rand method at 20°C. In addition, the number of samples is 5. Among the 5 samples, the maximum intrinsic viscosity is regarded as [η] _max and the minimum intrinsic viscosity is regarded as [η] _min , and [η] _max /[η] are calculated from the measurement results respectively. η] _min , and as an index of the non-uniform intrinsic viscosity of the polymer.

(2) The amount of diethylene glycol (DEG)

As far as the amount of diethylene glycol is concerned, after the polyester particles are pulverized, they are alkalized with potassium hydroxide-methanol solution, hydrolyzed with pure water, neutralized with terephthalic acid, and then analyzed by gas chromatography. The method is used to obtain the DEG content, and the mole percentage of DEG in the polymer is calculated by the following formula:

DEG mole % = DEG moles / (DEG moles + EG moles).

(3) Spinning operability

Using this modified polyester and ordinary PET (polyester) to spin ultra-fine segmented composite fibers, the degree of increase in spinning filtration and the number of broken filaments were evaluated using ○ (excellent), △ (normal), and × (poor) said.

(4) heat resistance

The above-mentioned ultrafine segmented composite fibers were subjected to twisting processing, and the evaluation was performed based on the powdered state and the untwisted state when the process passed, and represented by ○ (excellent), Δ (normal), and × (poor).

(5) Alkali solubility

Use the above-mentioned twisted yarn to make a tubular braided sample, carry out an alkali dissolution test with a 1% aqueous sodium hydroxide solution (bath ratio 50, 98°C), and evaluate it by its weight reduction rate, using ○ (excellent), △ (average) and × (poor).

Example 1

Terephthalic acid, ethylene glycol, and SIPE (accounting for 2.3 mol% of the acid component) were put into a slurry tank, and 45 ppm of trimethyl phosphate and 600 ppm of sodium acetate trihydrate were added to the polymer. , and adjust the pH value of the slurry to 5.2, and then continuously supply the slurry to the first esterification tank for a pressurized reaction at 270 ° C and 68.6 kpa, and continuously supply it to the second esterification tank, to the low Add 10% by weight of polyethylene glycol with an average molecular weight of 8000, 0.3% by weight of IRGANOX 245 (manufactured by Ciba-Geigy) as a hindered phenolic antioxidant, and 400 ppm of trioxide dissolved in ethylene glycol to the polymer. Antimony, set the molar ratio in the second esterification tank to 1.14 and carry out the esterification reaction under normal pressure, then continuously transfer the slurry to the initial polymerization tank and the late polymerization tank, and carry out the reaction continuously at 280°C Polymerization reaction obtained the modified polyester polymer described in (Table 1). In addition, the residence time from the esterification to the end of the polymerization reaction was 6.2 hours, and the production rate was 35 t/D.

Embodiment 2, Comparative Examples 1-9

Except for the copolymerization amount, addition amount, and total molar ratio of ethylene glycol/dicarboxylic acid components described in (Table 1), the same polymerization reaction as in Example 1 was carried out to obtain the modified polyester polymer described in (Table 1). . On the other hand, when the polymerization reaction was carried out under the same conditions as in Example 1 except that the total moles were set to 1.09, the polymer polymerization reaction could not proceed, and a modified polyester polymer could not be obtained.

Then, the ratio of this modified polyester polymer and common polyethylene terephthalate is 1:3 composite fibers are spun at a spinning speed of 3200 m/min to obtain 128 dtex/25 filaments partially oriented composite fibers. Table 1 describes the respective spinning operability. On the other hand, using the conjugate fiber at a linear speed of 200 m/min and stretching at 1.5, the heater was changed to 180°C to 210°C and twisted, and the heat resistance was evaluated based on the state of fuzz generation due to the heater temperature. , to obtain the results recorded in (Table 1). Then, the twisted yarn was subjected to an alkali weight reduction treatment with a 1% sodium hydroxide aqueous solution (bath ratio: 50, 98° C.), and the alkali solubility was evaluated from the weight reduction speed.

Examples 1 and 2, which are within the scope of the present invention, are suitable for any one of spinning operability, heat resistance during twisting, and alkali weight loss. However, Comparative Examples 1 to 9 are outside the scope of the present invention, and lack any of spinning operability, heat resistance, and alkali solubility.

Comparative Example 10

Terephthalic acid, ethylene glycol, and SIPE (2.3% [mol] to the acid component) were put into a slurry tank, and 45 ppm of trimethyl phosphate and 600 ppm of trihydrate were added to the polymer. Sodium acetate, and adjust the pH value of the slurry to 5.2, with the total molar ratio of ethylene glycol/dicarboxylic acid components being 1.0 into the batch pressurized esterification reactor, at 270 ° C, 68.6kpa pressurized Under the conditions, the esterification reaction was carried out for 2.5 hours to obtain an oligomer with an esterification rate of 84%. Then, 0.3% by weight of IRGANOX 245 (manufactured by Ciba-Geigy Corporation) as a hindered phenolic antioxidant and 10% by weight of polyethylene glycol with an average molecular weight of 8000 were added to the polymer, and The esterification reaction is completed. Then, 400 ppm of antimony trioxide dissolved in ethylene glycol was added, and the molar ratio of the total acid components and ethylene glycol was set to 1.2, and then moved to a polymerization reactor. While raising the reaction temperature to 280°C, the pressure was lowered from 101.3kpa to below 0.13kpa, and kept for 1 hour, and the polycondensation reaction was carried out at 280°C for 2.5 hours to obtain the modified polyester polymer described in (Table 1) . The subsequent evaluations were the same as in Example 1.

Comparative Example 11

Dimethyl terephthalate, 2.3 mol% of SIPE, ethylene glycol, and 600 ppm of sodium acetate trihydrate relative to the polymer were put into a batch-type esterification reactor at a molar ratio of 1.9, and added as an ester The manganese acetate tetrahydrate of 175 ppm relative to the polymer used as the catalyst for the exchange reaction, according to the usual method, under nitrogen flow, under normal pressure, while stirring, raised the temperature from 140 ° C to 235 ° C for 4 hours to complete the ester exchange reaction. Next, 8.0% by weight of polyethylene glycol with an average molecular weight of 3000, 0.3% by weight of IRGANOX245 (manufactured by Ciba-Geigy Corporation) as a hindered phenolic antioxidant, 350 ppm of trimethyl phosphate, and 400 ppm of dissolved Antimony trioxide in ethylene glycol was stirred and mixed, and then transferred to a batch type polymerization reactor. Then, at a reaction temperature of 280° C., the pressure was reduced from 101.3 kpa to below 0.13 kpa in 1 hour, and the state was maintained for 2.5 hours of polycondensation reaction to obtain the modified polyester described in (Table 1). The subsequent evaluations were the same as in Example 1.

In Comparative Examples 10 and 11, a batch-type polymerization method other than the production method of the present invention was used, and problems such as high intrinsic viscosity, many spinning breakages, and high spinning filtration pressure occurred.

【Table 1】 aggregation method SIPE(mol%) PEG (wt%/molecular weight) Mean limit viscosity [η]m [η]max/[η]min of polyester Addition amount of sodium acetate (ppm) Slurry pH Total molar ratio of ethylene glycol/dicarboxylic acid components DEG(mol%) Example 1 direct continuation method 2.3 10.0/8000 0.770 1.007 600 5.2 1.14 5.50 2 direct continuation method 2.3 10.0/3000 0.700 1.013 600 5.2 1.20 5.30 comparative example 1 direct continuation method 2.3 10.0/12000 0.822 1.014 600 5.2 1.14 5.25 2 direct continuation method 2.3 10.0/600 0.654 1.003 600 5.2 1.14 5.32 3 direct continuation method 2.3 10.0/8000 0.771 1.009 600 5.2 1.22 6.14 4 direct continuation method 2.3 10.0/8000 0.773 1.016 800 5.8 1.14 4.50 5 direct continuation method 2.3 10.0/8000 0.782 1.011 - 4.4 1.14 7.56 6 direct continuation method 1.8 12.0/3000 0.746 1.004 500 5.5 1.10 4.76 7 direct continuation method 2.3 13.5/8000 0.840 1.015 600 5.2 1.14 5.47 8 direct continuation method 3.5 10.0/8000 0.615 1.017 800 5.4 1.14 5.63 9 direct continuation method 2.3 8.0/3000 0.668 1.008 600 5.2 1.14 5.42 10 direct batch method 2.3 10.0/8000 0.822 1.055 600 5.2 1.20 5.70 11 DMT batch method 2.3 10.0/3000 0.815 1.028 - - - 3.10

【Table 2】 Spinning operability heat resistance Alkali solubility Example 1 ○ ○ ○ 2 ○ ○ ○ comparative example 1 ○ x ○ 2 x x ○ 3 x x ○ 4 x ○ △ 5 x x ○ 6 ○ ○ x 7 △ x ○ 8 x ○ ○ 9 ○ ○ x 10 x ○ ○ 11 x ○ ○

Claims (1)

1. the manufacture method of a polyester is characterized in that:

With terephthalic acid, ethylene glycol, the m-phthalic acid composition that contains the metal organic sulfonate base, polyalkylene glycol is a raw material, carry out the direct esterification reaction, condensation reaction and when making polyester, the m-phthalic acid composition that contains the metal organic sulfonate base that in sour composition, contains 2.0～3.0 moles of %, make dicarboxylic acid composition and ethylene glycol slurryization, adjusting PH is 4.5～5.5, be under 1.1～1.2 the condition in total mol ratio of ethylene glycol/dicarboxylic acid composition, make this slurry carry out the successive esterification, in the oligopolymer that is generated, be added in after the polyalkylene glycol that accounts for 9.0～13.0 weight % in the polymkeric substance, import polymerization tank successively, that carries out polyreaction under reduced pressure carries out a series of reaction continuously.

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