JPH0759634B2 - Polyester manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an antistatic polyester, and more particularly to a method for producing a polyester having stable productivity and excellent antistatic property and dispersibility of an antistatic agent. Regarding

2. Description of the Related Art Polyesters, especially polyethylene terephthalate, are widely used as fibers, films and other molded articles because of their excellent physical and chemical properties. However, polyester has a drawback that it is easily charged, which causes various troubles. For example, when processed into a film,
Problems such as winding around rolls in the film forming process, electric shock to workers, film surface stains due to suction of dust and dust, printing defects, film sickness between the film, etc.
Also, in the case of yarn, yarn irregularity, fluffing, entanglement, lack of convergence, adhesion after wearing after processing, and discomfort due to wrapping occur.

Therefore, there is a great need for imparting antistatic properties to polyesters, research on this has been made in the past, and many methods have been proposed, and some of them have been put to practical use. The method can be roughly classified into (i) a method of subjecting a film or thread to physical treatment and chemical treatment, and (ii) a method of modifying the polyester itself. As the method (ii), for example, there is a method in which a salt of an alkyl sulfonic acid and a polyalkylene glycol are blended in a polyester (eg, JP-A-52-47071 and JP-A-52-47072). As the salt, sodium salt is mainly used. However, the sodium salt of alkyl sulfonic acid has a problem of low dispersibility in polyester.

Object of the Invention As a result of research on an antistatic method which does not have such a problem, the present inventor has found that the lithium salt of alkylsulfonic acid exhibits excellent properties in terms of antistatic property and dispersibility in a polymer. However, in a subsequent study, this lithium salt had the drawback of increasing the concentration of diethylene glycol (DEG) in the polymer when it was produced in a continuous batch, making stable production difficult. Alkali metal salts such as sodium salt, potassium salt, etc. are unique phenomena unique to lithium salt. Furthermore, the dispersibility of lithium salt deteriorates as the number of production batches increases. It turned out to be flawed. The present inventor has reached the present invention as a result of further research on these improvement methods.

Therefore, an object of the present invention is to provide a method for producing a polyester having excellent antistatic property and dispersibility with stable productivity.

According to the present invention, a bifunctional carboxylic acid mainly containing terephthalic acid or an ester-forming derivative thereof and a glycol mainly containing ethylene glycol or an ester-forming derivative thereof are provided. In a method for producing a polyester by subjecting an esterification reaction or transesterification reaction to a polycondensation reaction of the resulting reaction product, a lithium salt of an alkylsulfonic acid may be added at a stage until the polycondensation reaction is completed or the polycondensation is completed. It is achieved by a method for producing an antistatic polyester, which comprises adding to the subsequent molten polyester and adding another alkali metal compound before the start of the polycondensation reaction and after adding the stabilizer.

The difunctional carboxylic acid used in the present invention is mainly terephthalic acid, but other difunctional carboxylic acids may be used in a small proportion. Examples of other difunctional carboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, and alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. And aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, diphenyl sulfone dicarboxylic acid, and benzophenone dicarboxylic acid. These copolymerization ratios are based on all acid components
It is preferably 20 mol% or less, more preferably 10 mol% or less.

Further, as the ester-forming derivative of the bifunctional carboxylic acid, a conventionally known derivative can be used,
Lower alkyl esters, especially methyl esters, are preferred.

Further, the glycol used in the present invention is mainly ethylene glycol, but other glycols can be used together in a small proportion. As other glycols, for example,
Examples thereof include 1, -propanediol, 1,4-butanediol, 1,6-hexanediol, neopetylene glycol, 1,4-cyclohexanedimethanol and P-xylylene glycol. The copolymerization ratio of these is 20 per total acid component.
It is preferably at most mol%, more preferably at most 10 mol%.

As the ester-forming derivative of glycol, a conventionally known derivative can be used.

The reaction between the acid component and the glycol component in the present invention is
This can be done by a conventionally known or accumulated method.

In the present invention using the lithium salt of an alkyl sulfonic acid as agent for imparting antistatic properties to a polyester, this lithium salt is represented by the following general formula R-SO ₃ Li (Here, R is an alkyl group having 8 to 20 carbon atoms ). Specific examples thereof include lithium octyl sulfonate, lithium nonyl sulfonate, lithium decyl sulfonate, lithium dodecyl sulfonate, lithium oleyl sulfonate, lithium stearyl sulfonate, and further alkyl group having 8 carbon atoms. Examples thereof include lithium alkyl sulfonates having an average carbon number of 13 to 16 and a carbon number of 20 to 20. The addition amount of these is usually 0.1 to 10% by weight based on the produced polyester.

This lithium alkyl sulfonate can be used in combination with polyalkylene glycol such as polyethylene glycol and polytetramethylene glycol. In this case, the amount of polyalkylene glycol added is preferably 0.1 to 10% by weight.

The lithium salt of alkyl sulfonic acid can be added during the transesterification or esterification reaction or during the polymerization reaction, at the time when the polymer is still in a molten state at the end of the polymerization reaction, but it may be added after addition of another alkali metal compound. preferable.

The other alkali metal compound used in the present invention is an alkali metal compound which is non-reactive with polyester (provided that it does not contain a metal salt of alkylsulfonic acid), and is a lithium or sodium monocarboxylate, carbonate or benzoate. Acid salts are preferred. Further, as the monocarboxylic acid, lower fatty acids such as acetic acid, propylene acid and butyric acid are preferable. It is necessary to add the other alkali metal compound before the start of the polycondensation reaction and after the addition of the stabilizer. Addition after the polycondensation reaction has little effect of suppressing DEG and lacks stable productivity in a continuous batch. Further, before the addition of the stabilizer, the alkali metal compound is trapped by the stabilizer, and its action is not sufficiently exhibited. In particular, the side effect suppressing effect of the alkyl sulfonic acid lithium salt added in the polycondensation reaction stage is lost. Also,
When the alkali metal compound is added at the above-mentioned addition time,
The lithium salt of alkyl sulfonic acid becomes fine particles, and the effect of improving dispersibility in the polymer is extremely large.

The metal salt of alkylsulfonic acid is generally insoluble in the polymer and poor in dispersibility and is likely to form large particles. Therefore, the polyester in which the metal salt of alkylsulfonic acid is blended is more likely to be used in the spinning process than that in which it is not blended. It has drawbacks such as a large increase in pack pressure and a rough surface when formed into a film. On the other hand, in the case of the polyester in which the alkali metal compound according to the present invention was added before the start of the polycondensation reaction and after the addition of the stabilizer, the dispersibility of the lithium salt was extremely excellent, and the increase in the pack pressure and the yarn breakage during the spinning process were greatly improved. Also, even when formed into a film, the surface is flat and can be sufficiently used for magnetic tape applications. The optimum addition amount of the alkali metal compound is 0.05 to 2.0 mol% with respect to the total acid components.

The stabilizer used in the present invention is preferably a phosphorus compound, and particularly preferably a compound represented by the following general formula.

(However, R _{1 to} R ₃ are each a hydrogen atom or an alkyl group) In the above formula, the alkyl group of R _{1 to} R ₃ is methyl, ethyl,
Lower alkyl groups such as propyl and butyl are preferred. These specific examples are widely known in the art, and they can be used in the present invention. The amount of the stabilizer added is preferably 0.01 to 0.5 mol% with respect to the total acid components. It is preferable to add the stabilizer at the time when the transesterification or the esterification reaction is substantially completed.

In the present invention, conventionally known reaction conditions can be used except that the above-mentioned additives are added at a predetermined time. At that time, it is preferable to use a compound known as a reaction catalyst of polyester as a catalyst. Further, other additives such as lubricants and matting agents can be added.

EXAMPLES The present invention will be described with reference to examples.

Various physical properties and characteristics in the examples were reached by the following methods.

(1) Surface resistivity Measured with a vibrating capacitance type micro-potential ammeter TR-84M type manufactured by Takeda Riken Co., Ltd. (20 ℃, 65% RH) (2) Charge potential half time Static Honest meter S-4104 of Shishido Shokai Co., Ltd.
Using a mold, when a voltage of -5 KV is applied from 2 cm above the sample for 30 seconds, the time (seconds) until the potential generated in the sample decays to a half value is obtained. (20 ℃, 65% RH) (3) Film surface roughness CLA [Center Line Ave (Center Line Ave
rage / center line average roughness)] In accordance with JIS B 0601, using a probe type surface roughness meter (SURFCOM 3B) manufactured by Tokyo Seimitsu Co., Ltd., the radius of the needle is 2 μm,
Put a chart under the condition of load of 0.07g, and extract the part of the measured length L from the film surface roughness curve in the direction of its center line. The center line of this extracted part is the X axis and the vertical direction is the Y axis. When the roughness curve is expressed by Y = f (x), the value given by the following equation is expressed in μm.

In this measurement, 8 pieces are measured with a reference length of 0.25 mm, and 3 pieces are removed from the largest value, and the average value of 5 pieces is shown.

Examples 1, 2 100 parts by weight of dimethyl terephthalate, ethylene glycol 7
A mixture of 0 parts by weight and 0.025 parts by weight of manganese acetate was heated with stirring to distill off generated methanol to cause a transesterification reaction for 90 minutes. Phosphoric acid was added to the obtained reaction product to 0.
035 parts by weight was added, and at 10 minutes after the addition of phosphoric acid, 0.1 mol% of the alkali metal salt shown in Table 1 was added. Next, 0.03 parts by weight of antimony trioxide was added, and then the reaction product was heated to 285 ° C.
The temperature is gradually raised to 60 mgHg.
For 30 minutes under a reduced pressure of 80 mm under a reduced pressure of 0.5 mmHg.
A polycondensation reaction was carried out for a minute. At that time, 1 part by weight of each of lithium alkylsulfonate and polyethylene glycol was added at 100 minutes after the start of depressurization.

By this method, polyester was continuously produced in four batches.

After drying the obtained polyester, it was melted at 300 ° C for 5 minutes and extruded in a thin film form from the die slit.
Cast on a cooling drum kept at 40 ° C. The thickness of the unstretched film after cooling was 350μ. The unstretched film was lengthwise (M
D) at a draw ratio of 3.7 times, and then in the tenter heated to 110 ° C in the width direction (TD) at a draw ratio of 4.0 times, and further 2 times.
Heat treatment was performed at 30 ° C. for 5 seconds. The biaxially oriented film thus obtained had a thickness of 25 μm. Table 1 shows the physical property values of these films.

Comparative Examples 1 and 2 The procedure of Example 1 was repeated except that lithium acetate was added after the initiation of polymerization (Comparative Example 1) or lithium acetate was not added (Comparative Example 2). The characteristics of the obtained polyester and its film are shown in Table 1.

From Table 1, it can be seen that in Comparative Examples 1 and 2, the amount of diethylene glycol (DEG) increases as the number of batches (Bx) increases, the particle dispersibility also decreases, and the film surface becomes rough.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C08L 67/02 KKB (56) Reference JP-A-61-115931 (JP, A) JP-A-49 -11986 (JP, A) JP-A-47-21492 (JP, A)

Claims (4)

[Claims] 1. A bifunctional carboxylic acid mainly comprising terephthalic acid or an ester-forming derivative thereof and an glycol mainly comprising ethylene glycol or an ester-forming derivative thereof are subjected to an esterification reaction or a transesterification reaction, and then obtained. In a method for producing a polyester by subjecting a reaction product to a polycondensation reaction, a lithium salt of alkylsulfonic acid is added to a molten polyester at a stage until the polycondensation reaction is completed or after the polycondensation reaction is completed, and another A method for producing an antistatic polyester, which comprises adding an alkali metal compound before the start of a polycondensation reaction and after adding a stabilizer. 2. The method according to claim 1, wherein the other alkali metal compound is a lithium or sodium monocarboxylate, carbonate or benzoate. 3. The production method according to claim 1, wherein the stabilizer is a phosphorus compound. 4. The process according to claim 1, wherein the lithium salt of alkylsulfonic acid is used in combination with polyalkylene glycol.