JP2831531B2 - Manufacturing method of hydrolysis resistant polyester fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester fiber having excellent hydrolysis resistance. More specifically, the present invention relates to a method for producing a polyester fiber excellent in hydrolysis resistance with less strong deterioration even after repeated high-temperature treatment with hot water or steam in post-processing such as dyeing processing, alkali weight reduction processing, pad / steam processing and the like. .

[0002]

2. Description of the Related Art Polyester fibers are widely used not only for clothing but also for industrial use because of their excellent properties.
However, fibers used under severe hydrolysis conditions, such as tire cords and dry canvas, are required to have stable mechanical properties, and various methods have been conventionally studied.

As a typical example, a method of adding various epoxy compounds to lower the carboxyl terminal group concentration of a polyester filament is well known.
For example, phenylglycidyl ether (JP-A-51-12)
658) and N-glycidyl phthalimide (Japanese Patent Application Laid-Open No. 54-6051). However, even if these compounds are added in the polymerization or melt-spinning process, the elongation of the filament decreases due to the gelling of newly generated alcoholic hydroxyl groups,
Furthermore, since the reactivity as an end group blocking agent is inferior, it is necessary to add in advance various ring-opening catalysts, for example, various phosphorus compounds such as triphenylphosphine or potassium iodide, and as a result, the degree of polymerization is reduced, There is a problem that the hydrolysis resistance of the polyester is insufficiently improved.

As a method of minimizing the adverse effect of additives on polyester filaments and reducing the concentration of carboxyl end groups, a method of adding a carbonate such as diphenyl carbonate or ethylene carbonate or a cyclic carbonate has been proposed. However, there is a problem that physical properties of the obtained filaments are deteriorated due to coloring due to generation of phenol during spinning, foaming due to decomposition of additives and generation of carbon dioxide gas,
Further, it is difficult to recover and separate phenol, and there is a problem in the polymerization step.

[0005] It is also known to use carboxyl end group blocking agents having one or more oxazoline rings in the molecular skeleton. In this method, not only the expected hydrolysis resistance effect cannot be obtained under severe conditions, but also, during spinning, thermal decomposition of the additive and coloring due to fuming are remarkable, resulting in a problem that the commercial value is reduced.

[0006] Further, a method of improving hydrolysis resistance by adding a carbodiimide compound to a polyester is also known. For example, a method in which a mono- or bis-carbodiimide compound or a polycarbodiimide compound is added and kneaded and spun in a short time to form a filament containing no unreacted carbodiimide agent (Japanese Unexamined Patent Publication No.
95517) and a method of adding a carbodiimide compound containing three or more carbodiimide groups in a molecule (Japanese Patent Publication No. 38-15220). Further, a specific carbodiimide compound remains in an unreacted state in a specific amount. Polyester monofilament (Japanese Unexamined Patent Publication No.
21388), and a method of adding a specific carbodiimide compound to a polyester containing a specific amount of phosphorus (Japanese Patent Publication No. 46607/1994). However, these methods are effective means for a monofilament having a large single-fiber fineness (that is, a small surface area), but improve the yarn production stability for a multifilament having a small single-fiber fineness (that is, a large surface area). It is necessary to lengthen the kneading time for this, and as a result, during the hot water treatment, the intrinsic viscosity is reduced, the strength is deteriorated, and marked coloring occurs.

Further, Japanese Patent Publication No. 47326/1991 discloses that
Carboxyl end group concentration exceeds 30 eq / ton and 47e
q / ton or less using polyester chips
Although it is described that a polyester filament having a large single-filament size of 00 denier / 192 filaments is produced, it is difficult to eliminate the unreacted carbodiimide compound even by this method, and the obstacle caused by the presence of unreacted substances is not solved. . In addition, this method cannot achieve a carboxyl end group concentration of less than 10 eq / ton necessary for exhibiting better hydrolysis resistance. Further, in this method, when a general carbodiimide compound is used, the obtained polyester multifilament is colored yellow.

[0008]

As described above, a known technique for improving the hydrolysis resistance of an industrial polyester filament having a large single-fiber fineness (small surface area) is described by a multifilament having a small single-fiber fineness (large surface area). Satisfactory results are not obtained when applied to filaments.

The reason is that multifilaments having a small single-fiber fineness have a remarkably large surface area, so that the inherent viscosity of the filaments and the deterioration of strength of the filaments due to the hot water treatment are reduced to industrial filaments having a large single-fiber fineness and a small surface area. It is extremely large in comparison. In particular, for industrial filaments, coloring is not a major problem, but for clothing filaments, "coloring" is fatal and must be avoided.

Accordingly, an object of the present invention is to provide a method for stably producing a polyester fiber which can withstand severe hydrolysis conditions and has a suppressed coloring, especially a polyester fiber having a single fiber fineness of 5 denier or less. To provide.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, 2,6,2 ', 6'
-By adding and mixing tetraisopropyldiphenylcarbodiimide in a liquid aliphatic linear polyester in advance and mixing it with molten polyester and spinning, the hydrolysis resistance is remarkably improved, and the conventional liquid polyester dispersant is used together. It was also found that the decrease in mechanical properties observed in the above was suppressed, and as a result of further studies, the present invention was reached.

That is, according to the present invention: In melt-spinning the polyester, 2, 100 parts by weight of the polyester-based dispersant which is in a liquid state at room temperature is used.
A method for producing a hydrolysis-resistant polyester fiber, comprising adding and mixing a composition obtained by mixing 1 to 100 parts by weight of 6,2 ', 6'-tetraisopropyldiphenylcarbodiimide to a melt of the polyester. 2. The carboxyl end group concentration of the polyester is 20 eq.
2. The method for producing a hydrolysis-resistant polyester fiber according to the above item 1, which is not more than 1 / ton. 3. The hydrolysis-resistant polyester fiber according to the above 1, wherein the amount of 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide added is 0.05 to 3.0 parts by weight per 100 parts by weight of the polyester. Manufacturing method. 4. The hydrolysis-resistant polyester according to the above item 1, wherein the polyester-based dispersant is an aliphatic polyester containing an aliphatic dicarboxylic acid having substantially 3 to 8 carbon atoms as an acid component and an alkylene glycol having 2 to 6 carbon atoms as a glycol component. Fiber manufacturing method. Is provided.

The polyester in the present invention is, for example,
90 repeating units of ethylene terephthalate in the molecular chain
The main object is a polyester containing at least 95 mol%, preferably at least 95 mol%. Polyethylene terephthalate is suitable as such a polyester, but may contain other copolymer components of 10 mol% or less, preferably 5 mol% or less. Examples of such a copolymer component include isophthalic acid, naphthalenedicarboxylic acid, adipic acid, oxybenzoic acid, diethylene glycol, propylene glycol, trimellitic acid, and pentaerythritol. In addition, such a polyester may contain additives such as a stabilizer and a coloring agent as needed.

The intrinsic viscosity and the carboxyl terminal group concentration of the polyester are preferably 0.6 or more and 20 eq / ton or less, respectively. If the intrinsic viscosity is less than 0.6, the strength and elongation characteristics of the obtained fiber are reduced. On the other hand, when the carboxyl end group concentration exceeds 20 eq / ton, the necessary amount of carbodiimide added increases, and it becomes difficult to obtain sufficient hydrolysis resistance.

In the present invention, a carbodiimide compound is added to the polyester to reduce the carboxy terminal concentration of the polyester. In this case, 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide is used as the carbodiimide compound. It is important that the carbodiimide is previously mixed with a liquid polyester-based dispersant, and that the mixture is added to a melt of the polyester. Even if other monocarbodiimides such as 2,2'-dimethyldiphenylcarbodiimide are used as the carbodiimide compound, the object of the present invention cannot be achieved.

The liquid polyester-based dispersant to which the carbodiimide is added and mixed is not particularly limited as long as it is a polyester which is in a liquid state at normal temperature, and may be adipic acid, sebacic acid,
An aliphatic dicarboxylic acid such as azelaic acid, an aromatic dicarboxylic acid such as phthalic acid or naphthalenedicarboxylic acid is used as an acid component, and ethylene glycol, propylene glycol, tetramethylene glycol, 1,3-butanediol, pentanediol, diethylene glycol, bisphenol A A polyester having an EO adduct or the like as a glycol component is used. Above all, aliphatic polyesters comprising an aliphatic dicarboxylic acid having 3 to 8 carbon atoms and a glycol component having 2 to 6 carbon atoms, particularly polypropylene sebacate, have a good compatibility with carbodiimide and are obtained by previously mixing. As the viscosity of the carbodiimide is reduced and the miscibility of the polyester with the melt is also improved, it is possible to greatly improve the hydrolysis resistance with a small amount while minimizing the thermal deterioration of the carbodiimide, and also reduce the physical properties of the fiber. Is also preferred because the amount of Note that these liquid polyesters are copolymerized with polyvalent carboxylic acids such as trimellitic acid, hemi-mellitic acid, and butanetetracarboxylic acid, and polyhydric alcohols such as pentaerythritol, dipentaerythritol, trimethylolpropane, glycerin, and sorbitol. And the terminal may be blocked with an aliphatic monocarboxylic acid such as oleic acid, lauric acid, or stearic acid or a monohydric alcohol such as octyl alcohol, 2-ethylhexyl alcohol, nonyl alcohol, or decyl alcohol. . Further, a polyalkylene glycol such as polyethylene glycol and polypropylene glycol may be copolymerized.

If the molecular weight of such a liquid polyester dispersion medium is too small, the mechanical properties of the resulting fiber tend to decrease, and the melt kneading property with the molten polyester also decreases. 3000-10000. As for the acid value and the hydroxyl value of the liquid polyester dispersion medium, the thermal stability of the polyester is improved by the combined use of carbodiimide, but if it is too large, the fiber properties tend to be reduced, so that the acid value is 2.0 mg KOH / g or less. And a hydroxyl value (based on the phthalic anhydride method) of 20.0 mgKOH / g or less.

The carbodiimide is added in an amount of 1 to 100 parts by weight based on 100 parts by weight of the liquid polyester dispersant.
Preferably, it is necessary to be 1 to 50 parts by weight. If the amount is less than 1 part by weight, the compounding amount of the dispersant of the liquid polyester becomes large as compared with the compounding amount of the carbodiimide with respect to the polyester. Unsatisfactory characteristics are also not preferred. On the other hand, when the amount exceeds 100 parts by weight, the viscosity of the mixture of the dispersant and the carbodiimide compound increases, and the measurement accuracy and the mixing and kneading properties of the carbodiimide are deteriorated when added and mixed into the molten polyester, thereby causing quality unevenness. Therefore, it is not preferable.

The method for previously mixing the carbodiimide with the liquid polyester-based dispersant is not particularly limited, and a conventionally known method can be employed. For example, a dispersion kneader such as a kneader, a ball mill, a sand mill, and a three-roll mill can be used, and these can be used in combination.

It is not necessary to adopt a special method for adding and mixing the mixture of the liquid polyester and the carbodiimide into the molten polyester. For example, the mixture is poured into the molten polyester before spinning while being measured by a gear pump or the like. After that, a method of mixing using a static mixer or the like and then discharging from a spinneret can be cited. Here, the amount of the mixture was 100% polyester.
It is preferable that the amount is 1 to 11 parts by weight with respect to parts by weight,
It is desirable that the amount of the carbodiimide added is 0.05 to 3.0 parts by weight based on 100 parts by weight of the polyester. When the amount of the mixture is out of the above range, there is a tendency to decrease the mechanical properties of the fiber or the condition of the spinning process.On the other hand, if the amount of the carbodiimide is too small, the object of the present invention is not achieved. If the content is too large, coloring or the physical properties of the fiber tend to be reduced.

The polymer discharged from the spinneret may be drawn in a conventional manner, for example, at a drawing speed of 1000 m / min, and then stretched at a draw ratio at which a desired elongation can be obtained. In particular, when the yarn is produced so that the single-fiber fineness is 5 deniers or less, the effect of the present invention is large, which is preferable.

[0022]

The reason why the production method of the present invention described above can stably obtain a polyester fiber having less unevenness of quality and good hydrolysis resistance as compared with the conventional method has not yet been elucidated. No, but it is estimated as follows. That is, the carbodiimide used in the present invention has good compatibility with the liquid polyester-based dispersant and the melt viscosity of the mixture is reduced, so that the amount of the dispersant used can be reduced. In addition, since the dispersant and the polyester have good compatibility, kneading and dispersion of the carbodiimide in the molten polyester can be achieved in a very short time, and the thermal decomposition of the carbodiimide and the reaction between the polyester and the dispersant can be suppressed. Since it is possible, it is presumed that fibers with little unevenness in quality can be obtained extremely stably.

Further, since carbodiimide can effectively block the carboxyl group at the terminal of the polyester without being thermally decomposed, it is presumed that the degradation of the hydrolysis resistance due to the heat degradation product is also improved.

[0024]

The present invention will be described in detail with reference to the following examples. In addition, the numerical value in an Example was measured by the following method.

(1) Strength, elongation Using a tensile tester, yarn length 25 cm, tensile speed 20 c
The measurement is performed under the conditions of m / min, temperature 20 ° C., and humidity 65%.

(2) Hydrolysis resistance test A polyester multifilament sample is cylindrically knitted and subjected to a hot water treatment in an autoclave at 100% relative humidity and 120 ° C for 100 hours. Assuming that the strength of the untreated sample is ST and the strength of the sample after treatment is ST ′, the strength retention (%) is determined by the following equation. Strength retention (%) = (ST ′ / ST) × 100

(3) Determination of Carboxyl Terminal Group Concentration According to a conventional method, 0.1 g of a polyester sample was dissolved in benzyl alcohol, and 0.02 mol / liter of Na was dissolved.
Titration was performed with an OH benzyl alcohol solution, and the carboxyl group concentration was calculated from the consumed amount (difference from the consumed amount of the blank).

(4) Intrinsic viscosity Measured with an orthochlorophenol solution at 35 ° C.

(5) Melt Viscosity The melt viscosity was measured at 25 ° C. with a No. 2 rotor using a Rion rotational viscometer (VT-04).

[0030]

Reference Example 1 Liquid polyester dispersion medium 10 shown in Table 1
To 0 parts by weight, 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide (hereinafter may be abbreviated as carbodiimide) is added at a ratio shown in Table 1, heated and stirred at 50 ° C for 3 minutes, and then cooled to 25 ° C. And the viscosity was measured. Table 1 shows the results.

[0031]

[Table 1]

[0032]

Example 1 The average molecular weight was 8,000 and the hydroxyl value was 17.
Poly (1,2-propylene) sebacate having 5 mg KOH / g and acid value of 1.27 mg KOH / g (dispersant A)
A liquid additive composition was obtained by kneading 42.8 parts by weight of carbodiimide with respect to 100 parts by weight.

A polyethylene terephthalate chip having an intrinsic viscosity of 0.64 and a carboxyl end group concentration of 19.0 eq / ton was heated and melted at 290 ° C. using an extruder and supplied to a melt spinning apparatus. At that time, the above composition was metered and supplied in a proportion of 4.96 parts by weight to 100 parts by weight of the molten polyester, and then mixed in a pipe having a static mixer manufactured by Kenix Corporation. The paper was discharged from the spinneret (average residence time from supply to discharge: 5 minutes) and wound at a speed of 1100 m / min. The obtained undrawn yarn was drawn according to a conventional method to obtain a multifilament of 75 denier / 24 filaments having a color value of L88.1 and b of 1.77. Table 2 shows the results.

Here, equivalent results were obtained using any of antimony, germanium and titanium as the polymerization catalyst for the polyester.

[0035]

Comparative Example 1 The polyester chip used in Example 1 was melted as it was in an extruder in the same manner as in Example 1, then discharged from a spinneret and spun and stretched to obtain a color value L.
A multifilament of 88.6, b2.12, 75 denier / 24 filaments was obtained. The results were as shown in Table 2.

[0036]

Comparative Example 2 The polyester chip used in Example 1
Carbodiimide was applied at a rate of 14.8 g / polyester 1 kg, melted by an extruder in the same manner as in Example 1, discharged from a spinneret, and spun and stretched to give a color value of L87.1 and b 6.75 of 75 denier / A multifilament of 24 filaments was obtained. The results were as shown in Table 2.

[0037]

Comparative Example 3 The polyethylene terephthalate chip used in Example 1 was heated and melted by the same method using the extruder used in Example 1, and 3.48 parts by weight based on 100 parts by weight of the molten polyester. Dispersant A in proportion
Was supplied in a constant amount to obtain a multifilament of 75 denier / 24 filaments under the same spinning and drawing conditions as in Example 1. The results are shown in Table 2.

[0038]

Comparative Example 4 A composition obtained by kneading 42.5 parts by weight of carbodiimide with respect to 100 parts by weight of dispersant A used in Example 1 was 4.9 with respect to 100 parts by weight of chips used in Example 1.
6 parts by weight, and mixed with an extruder under the same spinning and stretching conditions as in Example 1 to obtain a color value L8.
A multifilament of 75 denier / 24 filaments having 7.5 and b 5.27 was obtained. The results are shown in Table 2.

[0039]

Comparative Example 5 The polyester chip used in Example 1
Carbodiimide was adhered at a ratio of 0.6 g / polyester 1 kg, melted by an extruder in the same manner as in Example 1, discharged from a spinneret, and spin-drawn to obtain a multifilament of 75 denier / 24 filaments. The results were as shown in Table 2.

[0040]

Example 2 A composition obtained by kneading 42.9 parts by weight of carbodiimide with respect to 100 parts by weight of dispersant A used in Example 1 was added in an amount of 0.2 to 100 parts by weight of chips used in Example 1.
The mixture was mixed at a ratio of parts by weight to obtain a multifilament of 75 denier / 24 filaments under the same spinning and drawing conditions as in Example 1. The results are shown in Table 2.

[0041]

Comparative Example 6 Dispersant used in Comparative Example 3 was Dispersant B
(Average molecular weight 4000, hydroxyl value 19.31 mg KO
A multifilament was obtained in the same manner as in Comparative Example 3, except that H / g and poly (1,2-propylene) adipate having an acid value of 0.39 mgKOH / g were used.
The results were as shown in Table 2.

[0042]

Comparative Example 7 The dispersant used in Comparative Example 4 was Dispersant B
A multifilament was obtained in the same manner as in Comparative Example 4 except for changing to. The results were as shown in Table 2.

[0043]

Example 3 The dispersant used in Example 1 was Dispersant B
A multifilament was obtained in the same manner as in Example 1 except for changing to. The results were as shown in Table 2.

[0044]

[Table 2]

[0045]

According to the present invention, hydrolysis resistance is excellent,
Polyester fibers with low strength deterioration can be obtained even when repeatedly subjected to high temperature treatment with hot water or steam.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-104919 (JP, A) JP-A-60-210659 (JP, A) JP-A-58-163717 (JP, A) JP-A-50- 160362 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) D01F 6/62 306 D01F 6/62 302

Claims (4)

(57) [Claims] 1. A composition obtained by mixing 1 to 100 parts by weight of 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide with respect to 100 parts by weight of a polyester dispersant which is liquid at room temperature when melt-spinning polyester. A method for producing a hydrolysis-resistant polyester fiber, which comprises adding and mixing a product to a melt of the polyester. 2. The method for producing a hydrolysis-resistant polyester fiber according to claim 1, wherein the carboxyl terminal group concentration of the polyester is 20 eq / ton or less. 3. The hydrolysis resistance according to claim 1, wherein the addition amount of 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide is 0.05 to 3.0 parts by weight based on 100 parts by weight of the polyester. Method for producing conductive polyester fiber. 4. A polyester dispersant comprising an aliphatic dicarboxylic acid having substantially 3 to 8 carbon atoms as an acid component and having 2 to 2 carbon atoms.
The method for producing a hydrolysis-resistant polyester fiber according to claim 1, wherein the polyester is an aliphatic polyester containing an alkylene glycol as a glycol component.