JP2000212266A - Preparation of flame-retardant polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a flame-retardant polyester at a high productivity at a low cost by conducting esterification or transesterification in the presence of an organophosphorus compound in a specified amount in terms of phosphorus and an unsaturated aliphatic compound in a specified amount based on the organophosphorus compound. SOLUTION: The esterification or transesterification of at least one dicarboxylic acid (e.g. terephthalic acid) and at least one glycol (e.g. ethylene glycol) is conducted at 250 deg.C or higher in the presence of an organophosphorus compound of the formula in such an amount that the phosphorus content in the resultant polyester is 500 ppm or higher and an unsaturated aliphatic compound of the formula: X1-R4-X2 (e.g. itaconic acid) is in an amount of 0.9-1.2 mol per mol of the organophosphorus compound. Then, a catalyst (e.g. antimony dioxide) is added to the reaction system, which is then subjected to polycondensation at 220-290 deg.C to give a polyester. In the formulas, R1 and R2 are each H or a 1-12C hydrocarbon group; R4 is a 2-12C alkylene group having an unsaturated bond on the side chain or on the main chain; and X1 and X2 are each hyroxyl or carboxyl.

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 flame-retardant polyester with good productivity and at low cost.

[0002]

2. Description of the Related Art Polyester is used in addition to textiles for clothing and industrial use due to its excellent mechanical and chemical properties.
It is widely used for films for magnetic tapes, photographs, capacitors, and the like, molded articles such as bottles, paints, adhesives, and the like. In recent years, there has been an increasing demand for flame retardancy of synthetic fibers and various plastic products from the viewpoint of fire prevention.

Conventionally, various attempts have been made to impart flame retardancy to polyester, but from the viewpoint of performance and productivity, a method of copolymerizing a flame retardant at the time of polyester production is generally used. As the flame retardant-imparting substance used for this purpose, phosphorus compounds are considered to be advantageous from the viewpoints of flame retardancy, cost, environmental pollution and safety.

Japanese Patent Publication No. 55-41610 proposes a polyester obtained by copolymerizing a specific phosphorus compound having a divalent ester-forming functional group. However, this phosphorus compound is expensive, and there is a problem that if the copolymer is used in an amount sufficient to impart sufficient flame retardancy to the polyester, the raw material cost of the flame retardant polyester increases.

In Japanese Patent Publication No. 3-59087,
A production method for adding a specific phosphorus compound to a polyester having an unsaturated group has been proposed. This production method can use a relatively inexpensive phosphorus compound, but on the other hand, after polymerizing a polyester having an unsaturated group, it requires two steps of adding a phosphorus compound and performing an addition reaction. This is a complicated manufacturing method, and causes an increase in the cost of flame-retardant polyester.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a method for producing a flame-retardant polyester with good productivity and at low cost.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention provides, after one or more dicarboxylic acids or ester-forming derivatives thereof and one or more glycols, an esterification reaction or a transesterification reaction,
In producing a polyester via a polycondensation reaction, the amount of the organic phosphorus compound represented by the following general formula before the esterification reaction or the transesterification reaction is such that the phosphorus atom content in the polyester becomes 500 ppm or more, and the following general formula: The unsaturated aliphatic compound represented by the amount of the organic phosphorus compound added
The gist of the present invention is a method for producing a flame-retardant polyester, characterized in that it is added in a molar amount of 0.9 to 1.2 times.

[0008]

Embedded image However, R ₁ and R ₂ are the same or different groups and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. X ¹ -R ⁴ -X ^{2 wherein} R ⁴ is a divalent alkylene chain having 2 to 12 carbon atoms having an unsaturated bond in a side chain or a main chain, and X ¹ and X ² are a hydroxyl group or a carboxyl group. Represent.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The dicarboxylic acids constituting the polyester of the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, sebacic acid and dodecane diacid. And the like.

Further, trivalent or higher carboxylic acids such as trimellitic acid, trimellitic anhydride and pyromellitic acid can be used as necessary, and oxycarboxylic acids such as oxybenzoic acid can also be used. Further, an ester-forming derivative such as a methyl ester of the above carboxylic acid compound can also be used.

The glycols constituting the polyester of the present invention include ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol,
Examples include aliphatic glycols such as hexanediol and butanediol, alicyclic glycols such as cyclohexanedimethanol, and aromatic glycols such as an ethylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol S. In addition, tri- or higher-valent alcohols such as glycerin, trimethylolpropane, and pentaerythritol can be used as necessary.

These constituents are not particularly limited, and may be arbitrarily selected so that properties such as melting point, glass transition temperature, and mechanical strength of the polyester are suitable for the intended use. Can be.

In the present invention, the organophosphorus compound used must be one represented by the above formula, and among them, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- Oxide (hereinafter abbreviated as HCA) is preferably used.

The amount of the organic phosphorus compound added must be such that the phosphorus atom content in the polyester is at least 500 ppm, and preferably at least 1000 ppm. If the phosphorus atom content in the polyester is less than 500 ppm, the flame retardancy of the polyester will be insufficient. The upper limit of the phosphorus atom content is not particularly limited, but if it is too large, the mechanical strength of the polyester may be impaired.

In the present invention, it is necessary to add an unsaturated aliphatic compound represented by the above formula together with the organic phosphorus compound. Specific examples include maleic acid, itaconic acid,
Glutaconic acid, 2-butene-1,4-diol and the like can be mentioned, and among them, itaconic acid (hereinafter abbreviated as IA) is suitably used.

The amount of the unsaturated aliphatic compound added must be 0.9 to 1.2 times the molar amount of the organic phosphorus compound, and more preferably 1.0 to 1.1 times the molar amount. If the amount of the unsaturated aliphatic compound is less than 0.9 times the molar amount, the addition reaction of the organic phosphorus compound becomes insufficient and the polycondensation reaction of the polyester is hindered, requiring a long time for the reaction, In some cases, the reaction does not proceed until the polymerization degree reaches a certain level. On the other hand, if the molar amount exceeds 1.2 times, the polyester may gel, which is not suitable.

In the present invention, the organic phosphorus compound represented by the above formula and the unsaturated aliphatic compound represented by the above formula need to be added before the esterification reaction or the transesterification reaction. When the addition time of the organic phosphorus compound and the unsaturated aliphatic compound is after the esterification reaction or transesterification reaction, the addition reaction between the organic phosphorus compound and the unsaturated aliphatic compound becomes insufficient, and as a result, the polyester polycondensation reaction occurs. It is not suitable because it may be hindered or the polyester may gel.

In the present invention, the esterification reaction or transesterification reaction of the carboxylic acid, glycol, and unsaturated aliphatic compound (including the ester-forming derivative described above) is carried out by a conventional method. A compound addition reaction is also performed. The reaction conditions are not particularly limited, but it is preferable to carry out the reaction under normal pressure at a temperature of 250 ° C. or higher in order to promote the addition reaction of the organic phosphorus compound.

The polycondensation reaction is carried out by a conventional method until the desired degree of polymerization is reached. Usually in the presence of metal compounds such as antimony, germanium, tin, titanium, zinc,
It is preferable to carry out the reaction at a temperature of 220 ° C. to 290 ° C. under a reduced pressure of about 0.12 to 12 hPa. Further, if necessary, after the polycondensation reaction, adding a compound having an ester-forming functional group,
Depolymerization may be performed at a temperature of 240 ° C. or higher.

As long as the effects of the present invention are not impaired, antioxidants such as hindered phenol compounds, fluorescent agents, dyes, color tone improvers such as cobalt compounds, pigments such as titanium dioxide, An additive such as an ultraviolet absorber may be contained.

The flame-retardant polyester obtained in the present invention is:
Depending on its properties, it can be used in the production of fibers, films, bottles, paints, adhesives.

[0023]

Next, the present invention will be described in detail with reference to examples. In addition, the measuring method of the characteristic value in an Example is as follows. (1) Intrinsic viscosity [η] Using an equal weight mixed solvent of phenol and ethane tetrachloride,
It was measured at a temperature of 20 ° C. (2) Phosphorus atom content It was determined by a fluorescent X-ray method using a fluorescent X-ray analyzer system 3270 manufactured by Rigaku Corporation. (3) Flame retardancy Measured by the oxygen index (LOI) method according to JIS K 7201 A2 or JIS K 7201 B2. Accept 26% or more.

Example 1 The compounds shown in Table 1 were charged into an esterification reactor in the proportions shown in Table 1, and the esterification reaction was carried out under the conditions of a pressure of 0.1 MPaG and a temperature of 260 ° C. until the conversion reached 95% or more. went. The esterification reaction product was transferred to a polycondensation reactor, and then 0.4% by weight of titanium dioxide based on the polyester and 3 × 10 ^-4 moles of antimony trioxide based on 1 mole of the total acid component were added. The temperature was raised to 275 ° C. in 30 minutes, and the pressure was gradually reduced to 1.2 hPa or less after 60 minutes. A polycondensation reaction was carried out while stirring under these conditions until a predetermined degree of polymerization was obtained, to obtain a polyester having the [η] shown in Table 1 and a phosphorus atom content.

The polyester obtained by spinning and drawing this polyester by a conventional method using a conventional melt spinning apparatus was used as a tubular knitted fabric, and the flame retardancy was measured according to JIS K 7201 A2. Shown in

Example 2 The amount of the organic phosphorus compound added, the type of unsaturated aliphatic compound,
A polyester was produced in the same manner as in Example 1 except that the amount and the kind and amount of the polycondensation catalyst were variously changed as shown in Table 1.

Example 3 The compounds shown in Table 1 were charged into an esterification reactor at the ratio shown in Table 1, and the esterification reaction was carried out at normal pressure and at a temperature of 260 ° C. until the conversion reached 95% or more. . This esterified product was transferred to a polycondensation reaction vessel, and 4 moles per 1 mole of the total acid component.
× 10 ^-4 mol of tetrabutyl titanate was added and the temperature was reduced.
The temperature was raised to 260 ° C. in 30 minutes, and the pressure was gradually reduced to 1.2 hPa or less after 60 minutes. The polycondensation reaction was carried out under stirring under the above conditions until a predetermined degree of polymerization was reached.
A polyester having a phosphorus atom content was obtained.

This polyester is dissolved at a concentration of 30% by weight in a mixed solvent of equal weights of toluene and methyl ethyl ketone to give a polyethylene terephthalate fabric having a basis weight of 300 g / m ^2.
After being attached at 100% by weight and dried at 120 ° C. for 30 minutes, the results of measuring the flame retardancy according to JIS K 7201 B2 are shown in Table 1.

Example 4 and Comparative Examples 1 to 3 Except that the addition amount of the organic phosphorus compound, the type and amount of the unsaturated aliphatic compound, and the type and amount of the polycondensation catalyst were variously changed as shown in Table 1, A polyester was produced as in Example 3.

In Comparative Example 2, however, the polycondensation reactivity was low, and the reaction did not reach the desired degree of polymerization even after 7 hours of reaction, so the production of the polyester was interrupted. Comparative Example 3
The production of polyester was interrupted due to severe gelation during the polycondensation reaction.

[0031]

[Table 1]

As is clear from Table 1, in Examples 1 to 4, polyesters having the desired phosphorus atom content [η] were obtained, and the flame retardancy was good.

On the other hand, in Comparative Example 1, since the added amount of the organic phosphorus compound was too small, the phosphorus content of the obtained polyester was small, and sufficient flame retardancy was not exhibited. Further, in Comparative Example 2, the polycondensation reactivity was insufficient because the addition ratio of the unsaturated aliphatic compound to the organic phosphorus compound was too low, and the reaction required a long time. I couldn't get it. Further, in Comparative Example 3, the addition ratio of the unsaturated aliphatic compound to the organic phosphorus compound was too high to cause gelation during the polycondensation reaction, and a desired polyester could not be obtained.

[0034]

According to the present invention, in the esterification reaction or transesterification reaction step, the addition reaction of the organic phosphorus compound can also proceed, so that the flame retardant useful for applications such as fibers, films and adhesives. Polyester can be produced with good productivity and at low cost.

Continued on the front page F-term (reference) 4J029 AA03 AB04 AB05 AC02 AD01 AE01 AE02 AE03 AE11 AE13 BA02 BA03 BA05 BA08 BB13A BD06A BF09 BH02 CA02 CA06 CH02 DB01 DB13 HA01 HB01 JB123 JB163 JC601 JF181 JF321 JF361 KB03 KB371

Claims (3)

[Claims] 1. The method according to claim 1, wherein the at least one dicarboxylic acid or its ester-forming derivative and at least one glycol are
After the esterification reaction or transesterification reaction, when producing a polyester through a polycondensation reaction, the organic phosphorus compound represented by the following general formula before the esterification reaction or transesterification reaction has a phosphorus atom content in the polyester of 500 p
pm or more, and the unsaturated aliphatic compound represented by the following general formula is 0.9 to 1.2 with respect to the addition amount of the organic phosphorus compound.
A method for producing a flame-retardant polyester, characterized in that it is added twice as much. Embedded image However, R ₁ and R ₂ are the same or different groups and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. X ¹ -R ⁴ -X ^{2 wherein} R ⁴ is a divalent alkylene chain having 2 to 12 carbon atoms having an unsaturated bond in a side chain or a main chain, and X ¹ and X ² are a hydroxyl group or a carboxyl group. Represent. 2. The method for producing a flame-retardant polyester according to claim 1, wherein the unsaturated aliphatic compound is itaconic acid. 3. The method for producing a flame-retardant polyester according to claim 1, wherein the esterification reaction or the transesterification reaction is carried out at 250 ° C. or higher under normal pressure.