JPH01132823A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To obtain the title fiber having excellent mechanical properties, color tone and high-speed spinnability, by adding specific amounts of a diphenyl compound and a monocarboxylic acid compound to terephthalic acid and glycol, subjecting to polycondensation and spinning the product. CONSTITUTION:(A) Dicarboxylic acid (derivative) composed mainly of terephthalic acid and (B) a glycol (derivative) are added with (C) 0.01-50mol% (based on the component A) of a diphenyl compound of formula I (R is H or alkyl) (e.g., diphenyl-4,4'-dicarboxilic acid), (D) 0.01-20mol% (based on the component A) of compound of formula II (X is H or OCOCH3) and (E) 0.005-0.2mol% (based on the component A) of an alkali or alkaline-earth metal organic carboxylic acid salt (e.g., sodium acetate) and the obtained composition is subjected to polycondensation. The produced polymer is spun at a spinning speed of >=3,000m/min and passed through a zone extending from 10cm to 70cm below the spinneret and containing an atmosphere having a temperature of from Tf-100 deg.C to Tf+200 deg.C (Tf is softening point of the polymer) to obtain the objective fiber.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing polyester fibers, and more specifically to a method for producing polyester fibers, and more specifically, a method for producing polyester fibers with a hue that has excellent spinnability, etc., and excellent mechanical properties such as strength and Young's modulus. This invention relates to a method for producing good polyester fiber using only a spinning process.

(Prior Art) Polyesters, especially polyethylene terephthalate, have many excellent properties and are therefore widely used in various applications, especially in fibers.

Such polyesters are usually produced by esterifying terephthalic acid and ethylene glycol, transesterifying dialkyl terephthalate and ethylene glycol, or reacting terephthalic acid and ethylene oxide to form glycol of terephthalic acid. It is produced by producing an ester and/or a low polymer thereof, and then heating the product under reduced pressure to polycondense it until a predetermined degree of polymerization is achieved. The polyester thus obtained is generally put into practical use by being extruded in a molten state into a fiber form from a spinning nozzle and drawn. In addition, a method of subjecting intermediately oriented yarn (POY) obtained by spinning polyester at a winding speed of 2000 m7 minutes or more to a drawing false twisting process has also become widely used.

Furthermore, recently the winding speed of polyester has been increased to 5000 m7.
A method has been proposed in which polyester fibers having practically sufficient properties can be obtained only by the spinning process by performing melt spinning at a high speed of 8000 m/min or more, particularly 8000 m/min or more.

However, increasing the spinning speed, especially 5ooo m7
On the other hand, increasing the winding speed to more than a minute increases the number of single fiber breakages and yarn breakages during spinning, resulting in the resulting polyester fibers having many defects such as fuzz, which significantly deteriorates the passability of higher-order processing steps. do. This tendency becomes more pronounced as the spinning speed increases, the single fiber denier decreases, and the number of filaments increases;
Spinning at a winding speed of m/min or higher is extremely difficult.

On the other hand, both polyester long fibers and short fibers undergo post-processing,
With the improvement of productivity in spinning processes and the diversification of treatments for imparting functionality, there is a growing demand for high quality, particularly improvements in mechanical properties such as strength and Young's modulus.

In particular, in the so-called direct spinning method, which attempts to obtain polyester fibers that can withstand practical use only through the spinning process, it is necessary to increase the winding speed to at least 5,000 m/min or more, and even then, mechanical problems such as strength and Young's modulus are required. The mechanical properties are still lower than those of ordinary drawn yarn. Moreover, such high-speed spinning significantly increases the number of yarn breakages, so it cannot be used industrially.

Therefore, one of the inventors of the present invention investigated the occurrence of yarn breakage due to increased spinning speed, and found that one of the causes of such yarn breakage is crystallization under molecular orientation associated with increased spinning speed of polyester. Knowing that this is the case, we first published a method for suppressing crystallization under such molecular orientation in Japanese Patent Application Laid-Open No. 59-4742.
This was proposed in Publication No. 3 and Japanese Unexamined Patent Publication No. 193921/1983.

These methods are based on p-hydroxybenzoic acid (hereinafter referred to as PO
(sometimes referred to as BA) is added at any stage until the production of polyester is completed.

The polyester obtained in this way has a good color tone, and when subjected to high-speed spinning at a winding speed of 4000 m/min or higher, yarn breakage can be reduced; however, when the winding speed is 5000 m/min or higher, Yarn breakage still occurs frequently during spinning, and the mechanical strength of the resulting fibers is lower than that of ordinary drawn yarns.

In addition, one of the present inventors has proposed that in order to obtain fibers that are sufficiently practical using only the spinning process, a polyester that is subjected to some heat treatment in the spinning process and contains inert fine particles with an average particle size of 10 to 100 mμ is used. JP-A-60-81314 shows that the mechanical properties increase to a certain extent.
It was proposed in the publication.

(Problems to be Solved by the Invention) However, although the method described above does improve the mechanical properties such as the strength and Young's modulus of the fibers obtained, it is difficult to achieve even better mechanical properties for practical use. mechanical properties,
A polyester having a hue is desired.

An object of the present invention is to provide a method for producing polyester fibers having improved mechanical properties such as strength and Young's modulus, good color tone, and excellent high-speed spinnability.

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors added a specific diphenyl compound and/or a specific monocarboxylic acid compound during the polyester manufacturing process. In addition, the mechanical strength of the resulting fiber is improved by heating directly below the spinneret during high-speed spinning of polyester obtained by adding an alkali metal salt or alkaline earth metal salt of an organic carboxylic acid. We have discovered this and arrived at the present invention.

That is, in the present invention, the polyester spun yarn is passed through a temperature atmosphere ranging from 100° C. lower than the softening point of the polyester to 200° C. higher than the softening point of the polyester immediately below the spinneret, and then 3000m
When spinning at a take-up speed of /min or more, a bifunctional carboxylic acid mainly consisting of terephthalic acid and/or its ester-forming derivative is esterified with at least one glycol and/or its ester-forming derivative as the polyester. Formation of the difunctional carboxylic acid and/or its ester at any stage before the completion of the polycondensation reaction using a polyester obtained by polycondensation reaction of a reaction product subjected to a reaction or transesterification reaction. 0.01 to 50 mol% of the following (I
) Diphenyl compound represented by 2 and/or 0.0
1 to 20 mol % of a monocarboxylic acid compound represented by the following formula (II) is added, and an organic carboxylate of at least one metal selected from the group consisting of alkali metals or alkaline earth metals is added to the monocarboxylic acid compound represented by the following formula (II). o, oo for functional carboxylic acids and/or their ester-forming derivatives
This is a method for producing polyester fiber characterized by using polyester to which s~0.2 mol% is added.

R00C℃8goC0OR...CI) (CI)
, (It) in the formula, R is a hydrogen atom or carbon number] In the polyester of the present invention, the following general formula CI
) 0.01 to 50 mol% of the diphenyl compound represented by
and/or 0.01 to 20 mol% of a monocarboxylic acid compound represented by the following general formula [■], and at least one metal selected from the group consisting of alkali metals and alkaline earth metals. 0.005 of organic carboxylate
It is important to add ~0.2 mol%.

Xo-C5-C0OR・・・・・・([)-Ship type [I]
The diphenyl compound represented by the following general formula (n
I) diphenyl compounds, especially diphenyl-4
, 4'-dicarboxylic acid, dimethyl diphenyl-4,4'-dicarboxylate, and diethyl diphenyl-4,4'-dicarboxylate are preferred.

ROOC-Q-ol-C00R...[■] The amount of such diphenyl compound added must be 0.01 to 50 mol% based on the acid component of the polyester,
When the amount is less than 0.01 mol %, when such a polyester is subjected to high-speed spinning, yarn breakage occurs frequently, and the mechanical properties such as strength and Young's modulus of the obtained fibers remain low.

On the other hand, if the amount of the diphenyl compound added exceeds 50 mol%, the melt viscosity of the polyester increases, the filtration pressure during spinning (spinning pack pressure) increases, making normal spinning difficult, and also makes it difficult to perform normal spinning. It becomes difficult to wind at high speeds of more than 1 minute.

Examples of the monocarboxylic acid compound represented by the general formula [II] include p-oxybenzoic acid, methyl p-oxybenzoate,
Examples include ethyl p-oxybenzoate, acetoxybenzoic acid, and methyl acetoxybenzoate.

The amount of the monocarboxylic acid compound added is 0.01 to 20 mol%, preferably 0.1 to 10 mol%, based on the acid component of the polyester. If the amount added is less than 0.01 mol%, yarn breakage will occur frequently during high-speed spinning.

On the other hand, if the content of the monocarboxylic acid compound exceeds 20 mol%, not only will the polyester polycondensation time become longer and the productivity will decrease, but also yarn breakage will occur frequently during high-speed spinning, resulting in poor quality of the final fiber. Mechanical properties are also reduced.

As the organic carboxylate of at least one metal selected from the group consisting of alkali metals and alkaline earth metals,
Preferably, such metals are sodium, potassium, lithium, calcium, and magnesium, with sodium being particularly preferred. Preferred organic carboxylic acids include aliphatic carboxylic acids and aromatic monocarboxylic acids, including sodium acetate, sodium benzoate, and sodium montanate.

The amount of the organic carboxylate added is from o,oos to 0.2 mol% based on the acid component of the polyester, but if the amount added is less than o,oos mol%, yarn breakage occurs frequently during high-speed spinning. , the mechanical properties of the obtained fibers also remain low.

Moreover, if it exceeds 0.2 mol%, the filtration pressure (spinning pack pressure) during spinning will increase rapidly and yarn breakage will occur frequently.

In the present invention, when spinning using the above-mentioned polyester, the spun polyester yarn discharged from the spinneret is spread over a length of 10c+a or more and 701 or less from the bottom surface of the spinneret, and 100% longer than the softening point of the polyester. After passing through a temperature atmosphere within the range of 200°C higher than the softening point, preferably 70°C lower than the softening point, and 150°C higher than the softening point,
It is important to pick up at a speed of at least 1 minute. If the heating region is less than 10 cm from the bottom surface of the spinneret, the heating effect will not be sufficient and the effect of improving mechanical properties will not be sufficient. Moreover, when the value exceeds 70, yarn fluctuation becomes large, yarn breakage occurs frequently, and the mechanical properties of the obtained fibers also deteriorate. Furthermore, if the temperature in the heating region is less than 100° C. lower than the softening point of polyester, no improvement in the mechanical properties of the resulting fibers can be expected. On the other hand, if the temperature exceeds the softening point by 200 DEG C., the yarn tends to suffer from two-ing, resulting in frequent yarn breakage. Furthermore, if the take-up speed is less than 3000 m/min, the strength, Young's modulus, and other mechanical properties of the obtained fibers will be low, making it impossible to produce fibers that can withstand practical use only by the spinning process. Here, the softening point of polyester is obtained by the following measuring method. That is, 4
After immersing a x4 x 2 mm chip in silicone oil and setting a stainless steel needle with a diameter of 3 mm and a weight of 15.5 g on the chip, the temperature of the silicone oil was increased until the needle reached a temperature of 0.5n+m inside the chip. is the softening point.

In addition, the polyester referred to in the present invention mainly refers to polyethylene terephthalate consisting of a terephthalic acid component and an ethylene glycol component, but a part of the terephthalic acid component (usually 15 mol% or less, preferably 10 mol% or less) Even if the polyester is substituted with other difunctional carboxylic acid components, some of the ethylene glycol components (
It may also be a polyester in which the diol component (usually 15 mol% or less, preferably 10 mol% or less) is replaced with another diol component. Furthermore, the polyester may be copolymerized or mixed with various additives such as dye-facilitating agents, flame retardants, antistatic agents, hydrophilic agents, coloring agents, etc., as necessary.

Such polyesters are usually produced by esterifying terephthalic acid and ethylene glycol, by transesterifying a lower alkyl ester of terephthalic acid such as dimethyl terephthalate with ethylene glycol, or by reacting terephthalic acid with ethylene oxide. It is produced by producing a glycol ester of terephthalic acid and/or a low polymer thereof, and then heating the product under reduced pressure to cause a polycondensation reaction until a predetermined degree of polymerization is achieved.

Any catalyst can be used in these reactions as necessary. Among these, when employing the transesterification method, manganese compounds, zinc compounds, cobalt compounds, etc. are preferable as transesterification catalysts, and these may be used singly or in combination.
More than one species may be used in combination. The amount used is o, o
os to 0.1 mol% is preferred.

Further, as the polycondensation catalyst, antimony compounds, titanium compounds, and germanium compounds are preferable.

These may also be used alone or in combination of two or more, and the amount used is 0.003 to 0.1 based on the bifunctional carboxylic acid component.
Mol% is preferred, especially for antimony compounds 0.
0.015 to 0.05 mol% is preferred.

Also, in the present invention, phosphorus compounds can be used as stabilizers, and this is also preferred. As the phosphorus compound, any phosphorus compound that can be used as a stabilizer for polyester can be used, but phosphoric acid, phosphorous acid, and di- or triesters thereof are preferred, and esters having 1 to 6 carbon atoms are preferred. Alkyl esters and phenyl esters are preferred. Also preferred are products obtained by heat treating these alkyl esters in glycols, especially ethylene glycol. The appropriate amount of the phosphorus compound to be used is in the range of 0.001 to 0.5 mol % based on the bifunctional carboxylic acid component used as the polyester raw material. In addition, it is preferable to add the phosphorus compound at the time when the reaction in the first stage is substantially completed.The addition method may be arbitrary, and even if it is added as it is, it will not be added to the glycol, especially the same type of glycol as the glycol used as the polyester raw material. It may be added after being dispersed or dissolved.

(Function) The reason why the polyester fiber obtained by the production method of the present invention has excellent mechanical properties, good hue, and excellent spinnability is not yet clear, but it is thought to be as follows.

That is, by adding the diphenyl compound represented by general formula [I] and/or the monocarboxylic acid compound represented by general formula (If) in the amount specified in the present invention, the following can be achieved in relation to the reactivity of each compound. (IV), (V) and/
Alternatively, the structural unit represented by (Vl) is introduced into the polyester molecular chain or at the end of the molecule.

(OOC+OH1...(V)) By introducing the structural unit represented by (TV) into the molecular chain, the mechanical properties such as the strength and Young's modulus of the fiber obtained are improved, and the formula (V) A polyester having a structural unit represented by , that is, a terminal group, can suppress crystallinity during molecular orientation, improve mechanical strength in relation to interaction between polyester molecules, and improve spinnability during high-speed spinning. In addition, since the polyester having the structural unit represented by the formula (Vr) contains a flexible ether bond in the molecular chain, it can improve the spinnability during high-speed spinning and also improve the mechanical properties. Furthermore, since the polyester having the structural unit represented by the formula (TV) has improved heat resistance, the polyester also has a good color tone.

Further, an organic carboxylate of a metal selected from the group consisting of alkali metals and alkaline earth metals is added as an oriented crystallization inhibitor, and 101 or more 7
By heating over a length of 0c11 or less, the position of the development of the fine structure of the fiber shifts to the lower part of the spinning line, and the internal structure of polyester is formed at a position where the air drag is large and the temperature is low, resulting in The birefringence index of the fiber (Δ
n) increases and the density decreases, resulting in improved mechanical properties such as strength and Young's modulus of the resulting fiber.

As described above, according to the production method of the present invention, the polyester molecular chain itself is strengthened while suppressing crystallization during orientation.
In addition, it is presumed that by controlling the structural development of the fibers by heating under the spinneret, the mechanical properties of the resulting fibers can be improved, and fibers with excellent spinnability and color tone can be obtained.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

In the examples, parts are parts by weight, and [η] is the intrinsic viscosity determined from the value measured at 30°C in 0-chlorophenol solvent. The color tone value and b value, which represent the color tone of the polymer, are values measured using a Hunter type color difference meter, and the larger the L value, the better the white discoloration. It shows that it is strong. That is, the larger the L value and the smaller the b value, the better the hue. The softening point was measured by the penetration method.

Examples 1 to 13, Comparative Examples 1 to 9 Dimethyl terephthalate and dimethyl diphenyl-4,4'-dicarboxylate in the amounts shown in Table 1, 640 parts of ethylene glycol, and 0.31 parts of manganese acetate as a transesterification catalyst. (25 mmol% to acid component) was charged into a reactor equipped with a stirrer equipped with a rectification column and a methanol distillation condenser, heated from 140°C to 240°C, and the methanol produced as a result of the reaction was removed from the system. Transesterification reaction was carried out while distilling. 3 hours after the start of the reaction, the internal temperature was 24
The temperature reached 0°C and 3.20 parts of methanol was distilled out. Here, 0.22 parts (trimethylphosphny) as a stabilizer (
After adding 30 mmol% of acid component) and reacting for 10 minutes, 0.44 part of antimony dioxide (30 mmol% to acid component) was added as a polycondensation catalyst.
0 mmol% to acid component) and organic carboxylic acid metal salts of the type and amount shown in Table 1, and immediately after that,
The transesterification reaction was completed by adding paraoxybenzoic acid in the amount shown in the table.

Next, the obtained transesterification product was transferred to a polycondensation reactor equipped with a stirrer and a glycol condenser.
The temperature was gradually raised from 40° C. to 289° C., and the polycondensation reaction was carried out under normal pressure, and then the pressure was lowered to a high vacuum of 1 wHg, and the polycondensation reaction was carried out to obtain a polymer with [η] of 0.64.

The polyester thus obtained was spun at 300°C through a spinneret having 24 spinning nozzles each having a diameter of 0.27 m.
Discharges at a discharge rate of 6.6 g/min, 50C1 directly below the mouthpiece.
1 was changed to the temperature atmosphere shown in Table 1, and the sample was taken at a taking speed of 6000 m/min.

The number of yarn breaks during spinning is the number of yarn breaks when 1 ton of polyester is melt-spun, and the number of fluffs is expressed as the number of fluffs per 1 million m by counting the number of fluffs in the polyester fibers using a phototube method.

The strength and Young's modulus of the obtained yarn are also shown in Table 1.

In Table 1, Δn indicates the birefringence index of the polyester fibers, and the larger Δn is, the greater the degree of orientation of the fibers. Further, ρ indicates the density of the polyester fiber, and the larger p is, the higher the crystallinity of the fiber is.

(This page, blank space below) As is clear from the results in Table 1, diphenyl-4,4
When the amounts of dimethyl '-dicarboxylate, paraoxybenzoic acid, and organic carboxylic acid metal salts are outside the range of the present invention (Comparative Examples 1 to 4.5 to 6.9), the fiber physical properties are not improved. The number of spun yarn breaks and the number of fluffs were high, and the color tone of the polymer was poor in some cases. On the other hand, when the above-mentioned substances were added within the scope of the present invention (Examples 1 to 3), the fiber properties were improved, the spinning property was excellent, and the color tone of the polymer was also good.

Examples 14 to 19, Comparative Examples 10 to 15 Polymers produced in the same manner as in Example 4 except that the take-up speed during high-speed spinning and the heating atmosphere conditions under the spindle were changed as shown in Table 2. The physical properties and spinning characteristics were evaluated. The results are shown in Table 2.

(This page, blank spaces below) As is clear from the results in Table 2, when the heating conditions on the nozzle were outside the range of the present invention (Comparative Examples 10 to 13), yarn breakage occurred frequently and the number of fuzz occurred. In many cases, the physical properties of the fibers do not improve much. In addition, if the take-up speed is outside the scope of the present invention (
Comparative Examples 14 and 15) also had poor fiber properties, frequent yarn breakage, and fuzzing. On the other hand, when the heating conditions on the spinneret and the take-off speed are within the range of the present invention, the fiber properties are good, and the yarn breakage and fuzz are less likely to occur, and the spinning characteristics are also good.

(Effects of the Invention) The method of the present invention has the effect that it is possible to provide polyester fibers that are excellent in color tone and spinnability, and also have excellent fiber properties such as Young's modulus and strength through the spinning process alone.

Claims (1)

[Claims] 1. Spun polyester yarn at 10 to 70 cm directly below the spinneret.
After passing through a temperature atmosphere ranging from 100°C lower than the softening point of the polyester to 200°C higher than the softening point of the polyester for a duration of A reaction product obtained by esterifying or transesterifying a difunctional carboxylic acid and/or its ester-forming derivative mainly consisting of difunctional carboxylic acid and/or its ester-forming derivative with at least one glycol and/or its ester-forming derivative is subjected to a polycondensation reaction. Using the polyester obtained at least, and at any stage before the completion of the polycondensation reaction, 0.01 to 50 mol% of the following [[ I ] Diphenyl compound represented by the formula and/or 0.01 to 20 mol%
A monocarboxylic acid compound represented by the following formula [II] is added to the difunctional carboxylic acid and an organic carboxylate of at least one metal selected from the group consisting of alkali metals or alkaline earth metals. / or 0.005 to 0.2 mol% based on its ester-forming derivative
A method for producing polyester fiber, characterized by using added polyester. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・〔I
〕 ▲There are mathematical formulas, chemical formulas, tables, etc. ▼...
I] “In the formulas [I] and [II], R is a hydrogen atom or a carbon number of 1
or 2 alkyl group, X is a hydrogen atom or -
Indicates OCOCH_3. 2. The method for producing polyester fibers according to claim 1, wherein the diphenyl compound represented by the general formula [I] is a compound represented by the following formula [III]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[III
] "In the formula, R represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms." 3. Claim 1 in which the alkali metal or alkaline earth metal is lithium, sodium, potassium, magnesium, or calcium. A method for producing polyester fibers as described in Section 1. 4. The method for producing polyester fibers according to claim 1, wherein the organic carboxylic acid is an aliphatic carboxylic acid and/or an aromatic monocarboxylic acid.