JPH07216066A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester having sufficiently high molecular weight, excellent thermal stability and hydrolysis resistance and good color tone in a short time by reacting an aromatic dicarboxylic acid with a hexanediol in the presence of a titanium compound and a group II metal compound. CONSTITUTION:This polyester is produced by reacting a bifunctional carboxylic acid composed mainly of an aromatic dicarboxylic acid (preferably terephthalic acid) or its lower alkyl ester with a glycol composed mainly of 1,6-hexanediol in the presence of a titanium compound (preferably a tetraalkyl titanate such as tetra-n-propyl titanate or tetra-n-butyl titanate) and a group II metal compound (preferably a magnesium compound).

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 polyester, particularly polyester using 1,6-hexanediol as a main component of glycol.

[0002]

2. Description of the Related Art Conventionally, polyesters using 1,6-hexanediol as a glycol component, especially polyhexamethylene terephthalate, have been produced using a titanium compound as a polymerization catalyst. Methods such as increasing the amount of catalyst, increasing the polymerization time, and increasing the polymerization temperature have been adopted. But,
The increase in the molecular weight was not sufficient, and conversely, the molecular weight decreased during the polymerization, or the molecular weight decreased during recovery from the polymerization vessel, making it difficult to stably produce a high molecular weight product.

Recently, polyhexamethylene terephthalate having a high molecular weight has been demanded by many users, and high performance polyhexamethylene terephthalate having good color tone and thermal stability has been obtained. It has become important to manufacture at fast polymerization rates.

[0004]

An object of the present invention is to use an aromatic dicarboxylic acid or a lower alkyl ester thereof as a main component of a bifunctional carboxylic acid or a lower alkyl ester thereof, and a 1,6- In the polycondensation reaction of polyester using hexanediol, the polymerization rate is sufficiently high, the obtained polyester has a sufficiently large molecular weight, and the thermal stability and hydrolysis resistance are excellent and the color tone is good. It is to provide a method for producing a polyester.

[0005]

The present invention has been made to solve the above problems, and its gist is to provide a difunctional carboxylic acid containing an aromatic dicarboxylic acid as a main component or a lower alkyl ester thereof. When a polyester containing 1,6-hexanediol as a main component is reacted to produce a polyester, the polycondensation reaction is performed by a titanium compound and
It exists in the manufacturing method of polyester characterized by performing in the presence of a II group metal compound.

The present invention will be described in detail below. Examples of the bifunctional carboxylic acid component used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and diphenyldicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, and oxalic acid. Examples of the acid include aromatic dicarboxylic acid as a main component, and it is preferable to use terephthalic acid among them, usually 75 mol% or more, preferably 80 mol% or more, and most preferably 90 mol% or more. These aromatic dicarboxylic acids or aliphatic dicarboxylic acids are 1
It is possible to use one kind or a mixture of two or more kinds.

The lower alkyl ester component of the bifunctional carboxylic acid used in the present invention includes lower alkyl esters of aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and diphenyl dicarboxylic acid, adipic acid and sebacic acid. Examples thereof include lower alkyl esters of aliphatic dicarboxylic acids such as succinic acid and oxalic acid, but it is preferable to use lower alkyl esters of aromatic dicarboxylic acids as a main component, of which dimethyl terephthalate is used, usually 75 mol% or more, preferably Is 80 mol% or more, and most preferably 90 mol% or more. The lower alkyl ester of these aromatic dicarboxylic acids or the lower alkyl ester of aliphatic dicarboxylic acids is 1
One kind or two or more kinds may be mixed and can be arbitrarily selected depending on the purpose.

As the lower alkyl ester component, methyl ester is mainly targeted, but one kind of ethyl ester, propyl ester, butyl ester and the like may be mixed, or two or more kinds thereof may be mixed and may be arbitrarily selected depending on the purpose. it can.

In addition to these, a small amount of a trifunctional or higher carboxylic acid component such as trimellitic acid may be used, and a small amount of an acid anhydride such as trimellitic anhydride may be used. It can usually be said that it is preferable to use a lower alkyl ester component of a bifunctional carboxylic acid.

Examples of glycol components other than 1,6-hexanediol used in the present invention include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol and poly (oxy). Examples thereof include alkylene glycols such as ethylene glycol, polytetramethylene glycol, and polymethylene glycol. If necessary, one kind of these may be used, or two or more kinds may be mixed and used, and can be arbitrarily selected depending on the purpose.
Furthermore, a small amount of a polyhydric alcohol component such as glycerin may be used, or a small amount of an epoxy compound may be used.

The proportion of the 1,6-hexanediol component in the glycol component is usually 75 mol% or more, preferably 80 mol% or more, and most preferably 90 mol% or more.

The titanium compound used in the present invention is preferably a tetraalkyl titanate, specifically, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl. Titanate, tetracyclohexyl titanate, tetrabenzyl titanate, or a mixed titanate thereof.
Of these, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate are particularly preferable. Also, two or more of these titanium compounds may be used in combination.

The amount of titanium compound added is usually 50-300 PPM, preferably 100-200 PPM, and particularly preferably 120-300 Pt based on the polyester produced.
It is 180 PPM.

The Group II metal compound used in the present invention is a compound of a metal element contained in Group II of the Synchronous Table, and examples thereof include magnesium compounds, zinc compounds and calcium compounds.

Examples of magnesium compounds include magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate and the like. Examples of the zinc compound include zinc acetate, zinc hydroxide, zinc phosphate, zinc oxide and the like. Examples of the calcium compound include calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide and the like.

Of these, Group IIA metal compounds, especially magnesium compounds, are preferable in terms of improvement in polymerization rate, thermal stability of the produced polyester, hydrolysis resistance, color tone, etc. Magnesium acetate is preferable in terms of improvement in polymerization rate and resistance to hydrolysis. It is most preferable in terms of improvement of hydrolyzability (reduction of the number of terminal COOH groups), solubility in 1,4-butanediol (formation of foreign matter), and the like.

The amount of the Group II metal compound is the molar ratio of the Group II metal to titanium in the titanium compound, that is, the molar ratio of M / Ti (where M is the Group II metal). It is usually 0.5 to 2.5,
From the viewpoint of polymerization rate, thermal stability (number of terminal COOH groups), and color tone, 0.7 to 2.0 is preferable, and 0.9 to 0.9 is more preferable.
It is 1.5.

By using a titanium compound and a Group II metal compound, especially a magnesium compound, the polymerization rate can be improved and the content of the titanium compound can be reduced, and the color tone of the produced polymer is remarkably improved.

In the present invention, the transesterification step of the alkylene glycol component containing 1,6-hexamethylenediol as the main component and the lower alkyl ester component of the difunctional carboxylic acid containing dimethyl terephthalate as the main component, and the subsequent polycondensation When a polyester such as poly (1,6-hexamethylene terephthalate) is produced via the reaction step, these reaction conditions are not particularly limited, and known reaction conditions are applied as they are. For example, the alkylene glycol component / lower alkyl ester component of difunctional carboxylic acid at the time of transesterification is 2.0 or less, preferably 1.0 to 1.6 in molar ratio, and the transesterification reaction is 120 to 280 ° C, preferably 1
It is carried out at 40 to 240 ° C. for 2 to 4 hours, and then, as a polycondensation reaction under a reduced pressure of 3 torr or less, at a polymerization temperature of usually 230 to 270 ° C., preferably 245 to 255 ° C.
Conditions such as ~ 5 hours can be adopted. When the reaction temperature of the polycondensation reaction is 255 ° C. or lower,
The thermal decomposition reaction is suppressed and the terminal COOH groups are easily reduced.

The titanium compound may be added at the start of transesterification, during transesterification, after transesterification, at the time of polycondensation, etc., but it is preferable to add it separately at the start of transesterification and before the polycondensation reaction. .

The magnesium compound may be added at the start of transesterification, during transesterification, after transesterification, at the time of polycondensation, etc., but it is added at the end of transesterification or before the start of polycondensation. It is preferable in terms of color tone and the like.

In addition, various additives such as heat stabilizers, oxidation stabilizers, crystal nucleating agents, flame retardants, antistatic agents, mold release agents, ultraviolet absorbers, etc. within the range of not impairing the properties of polyhexamethylene terephthalate. May be added.

According to the method of the present invention, the polymerization rate is greatly improved as compared with the conventional method, so that the productivity can be improved and the polymerization temperature can be lowered if necessary, and as a result, the high polymer can be obtained. It is also possible to reduce the concentration of terminal COOH groups, and it is easy to obtain a good color tone.

[0024]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "part" means "part by weight", and the intrinsic viscosity (IV) is 30 in phenol / tetrachloroethane (1: 1 weight ratio).
It is obtained from the solution viscosity measured at ° C.

The terminal carboxyl group [COOH] is prepared by dissolving the polymer in benzyl alcohol and adding 0.1N NaOH.
It is a value determined by the above, and is a carboxyl group equivalent per 10 ⁶ g.

Example 1 Dimethyl terephthalate 13
80 ppm (in terms of titanium metal) of tetrabutyl titanate was added to 2.4 parts and 96.7 parts of 1,6-hexanediol, and transesterification was performed at 150 to 215 ° C. for 3 hours. 15 minutes before the end of the transesterification reaction, magnesium acetate / tetrahydrate was added so that the Mg / Ti molar ratio was 1.2, and a hindered phenolic antioxidant (Irganox 1010: manufactured by Ciba Geigy) To 600
ppm was added. Next, tetrabutyl titanate 8
0 ppm was added and the polycondensation reaction at 260 ° C. was started.
The polycondensation reaction was gradually reduced from atmospheric pressure to 1 Torr over 85 minutes, simultaneously raised to 260 ° C., and thereafter continued at 250 ° C. under a reduced pressure of 1 Torr or less. The reaction was terminated when the predetermined stirring torque was reached, and the PHT polymer was taken out. The polymerization time at that time and the intrinsic viscosity of the obtained PHT polymer were measured. Further, the polymerization rate (inherent viscosity / polymerization time) was compared from the intrinsic viscosity of the obtained PHT polymer and the polymerization time. The results are shown in Table-1.

Example 2 The same reaction as in Example 1 was carried out except that the polycondensation reaction temperature in Example 1 was 250 ° C.

[Examples 3 to 4] Except that the amount of magnesium acetate / tetrahydrate added in Example 2 was changed to 0.7 (Example 3) and 2.0 (Example 4) in terms of Mg / Ti ratio. Example 2
The same reaction was carried out.

[Examples 5 to 6] In place of the magnesium acetate / tetrahydrate in Example 2, calcium acetate / monohydrate (Example 5) or zinc acetate / dihydrate (Example 6) was added. Carried out the same reaction as in Example 2.

Comparative Example 1 The same reaction as in Example 1 was carried out except that magnesium acetate / tetrahydrate was not added in Example 1.

Comparative Example 2 The same reaction as in Example 2 was carried out except that magnesium acetate / tetrahydrate was not added.

Table 1 shows the types and amounts of titanium compounds used in Examples 1 to 6 and Comparative Examples 1 and 2, and the types and amounts of Group II metal compounds added. Table 1 also shows the temperature and time of the polymerization reaction, the intrinsic viscosity of the obtained polyester, the polymerization rate obtained based on the intrinsic viscosity, and the COOH group equivalent of the polymer terminal.

From Table 1, in the case of Example 1, a polymer having substantially the same intrinsic viscosity as that of Comparative Example 1 was obtained, but the polymerization time was as short as about 2/3 and the polymerization rate was remarkably high. It turns out to be fast. Further, since the terminal carboxyl group value is also low, it can be seen that a polymer having excellent thermal stability was obtained.

[0034]

[Table 1]

[0035]

Industrial Applicability By producing a polyester according to the method of the present invention, a polyester having a sufficiently large molecular weight, excellent thermal stability and hydrolysis resistance, and a good color tone can be obtained in a short polymerization reaction time. Since the obtained polyester is crystalline and has a low melting point, it can be used as a binder for polyester such as polyethylene terephthalate, or as a heat seal material, an alloy material or the like.

Claims (3)

[Claims] 1. A bifunctional carboxylic acid containing an aromatic dicarboxylic acid as a main component or a lower alkyl ester thereof,
When producing a polyester by reacting with glycol containing 1,6-hexanediol as a main component, a polycondensation reaction is carried out in the presence of a titanium compound and a Group II metal compound. . 2. With respect to titanium in the titanium compound,
The proportion of the Group II metal in the Group II metal compound is 0.5 to 2.5 times in terms of molar ratio.
The method for producing a polyester according to 1. 3. The method for producing a polyester according to claim 1, wherein the Group II metal compound is a magnesium compound.