JPS5834492B2 - Polyester Noseizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyester having a low content of terminal carboxyl groups.

Polyesters, especially aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate,
It is known to be useful as a material for fibers, films, manufactured products, etc.

Methods for producing such polyester include transesterifying ethylene glycol or tetramethylene glycol and dimethyl terephthalate, or transesterifying ethylene glycol or tetramethylene glycol with terephthalic acid, or transesterifying ethylene glycol or tetramethylene glycol with terephthalic acid. A method is usually used in which a bisglycol ester of terephthalic acid and/or a low polymer thereof is formed by an addition reaction, and the bisglycol ester of terephthalic acid and/or a low polymer thereof are subjected to heat condensation polymerization in a molten state under reduced pressure. It is being

Although this polycondensation reaction proceeds without a catalyst, it is extremely slow and is therefore generally carried out in the presence of a catalyst such as antimony dioxide or titanium tetraalkoxide.

Furthermore, since the reaction rate is faster at higher temperatures than at lower temperatures, the polycondensation reaction of polyester is usually carried out at a high temperature of 250 to 300'C.

Since polyester polymerization is generally carried out at the above-mentioned high temperatures, a small proportion of decomposition reactions occur constantly at the same time as the polycondensation reaction, resulting in an increase in the concentration of carboxyl groups at the terminals of the polyester.

Conventionally, a compound represented by the general formula -C-R'-C- represents a cyatyl residue and R and R' represent divalent organic residues is added to a polyester and reacted with the compound to determine the degree of polymerization of the polyester. There are known ways to raise it.

(See British Patent No. 693645). However, although this method has the advantage of producing a polyester with a high degree of polymerization in a relatively short time, it cannot be said to be a sufficient method in terms of producing a polyester with a low content of terminal carboxyl groups.

As a result of intensive research aimed at improving the above method, the present inventor discovered that bislactam oxalate has an excellent effect on improving the degree of polymerization and simultaneously reducing the concentration of terminal carboxyl groups, and has arrived at the present invention. .

That is, the present invention provides a polyester having an intrinsic viscosity of 0.15 or more, which is characterized by reacting a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main dihydroxy component with bislactam oxalate in a molten state. This is the manufacturing method.

The polyester used in the method of the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main dihydroxy component. A small proportion of polyfunctional compounds such as butane-1,2,4-tricarboxylic acid, trimellitic acid, pyromellitic acid, 5-oxyisophthalic acid, 2゜4-dioxyterephthalic acid, etc. are copolymerized. Good too.

The aromatic dicarboxylic acid components constituting the polyester include phthalic acid, isophthalic acid, terephthalic acid, methylterephthalic acid, methylisophthalic acid, and naphthalene-2.
, 6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-1゜5-dicarboxylic acid, tetralin-
1,5-dicarboxylic acid, tetralin-2,6-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, biphenyl-3,4'-dicarboxylic acid, 1,2,3,4,5゜6
-hexahytrobiphenyl-4,4'-dicarboxylic acid,
Examples include diphenylsulfone-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenylketone-4,4'-dicarboxylic acid, and diphenoxyethane-4,4'-dicarboxylic acid. can.

Carboxylic acid components that may be used in smaller proportions include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, cepatic acid, decamethylene dicarboxylic acid, etc.; cyclohexanedicarboxylic acid, bicyclohexyl-4 , 41-dicarboxylic acid, cyclobutanedicarboxylic acid, decalin-1,4-dicarboxylic acid, decalin-2,
Alicyclic dicarboxylic acids such as 6-dicarboxylic acid; Aliphatic oxycarboxylic acids such as ω-oxycaproic acid, ω-oxyundecanoic acid, etc.; P-oxybenzoic acid, P-β-hydroxyethoxybenzoic acid, P Examples include aromatic oxycarboxylic acids such as -(P-β-hydroxyethoxy)phenylbenzoic acid and the like.

Furthermore, examples of the aliphatic glycol component include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, and the like.

Further, dihydroxy components that may be used in small proportions include:
Cyclohexane-1,4-diol, cyclohexane-
Alicyclic glycols such as 1,4-dimethatool, decalin-2,6-dimethatool, etc.; hydroquinone, bisphenol-A, 4,4'-dioxybiphenyl, 4,4
Aromatic dioxy compounds such as 1-dioxydiphenyl sulfone, 1,1-bis(P-oxyphenyl)cyclohexane, etc.; 1,4-bis(β-hydroxyethoxy)benzene, 4,4'-bis(P-β -Hydroxyethoxyphenyl)-sulfone 2.Aliphatic glycols containing aromatic nuclei such as 2-bis(P-β-hydroxyethoxyphenyl)propane; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene- Examples include polyethers such as glycols.

The polyester referred to in the present invention is, for example, (1) a reaction product of a dicarboxylic acid mainly consisting of an aromatic dicarboxylic acid or its lower alkyl ester or aryl ester and an aliphatic glycol, (2) a reaction product mainly consisting of an aromatic dicarboxylic acid. Monomers and/or low polymers thereof obtained by the reaction of dicarboxylic acids and ethylene oxide or ethylene carbonate; (3) Monomers obtained by the reaction of aromatic dicarboxylic acids and oxycarboxylic acids with ethylene oxide or ethylene carbonate. It is produced by reacting a monomer and/or a low polymer thereof, or (4) a reaction product of an aromatic dicarboxylic acid halide and an aliphatic glycol, etc. by a conventionally known method. It has a hydroxyl group or a carboxyl group.

Among these, particularly preferred polyesters have a melting point of 15
It is a polyester with a temperature of 0°C or higher.

In the present invention, when a polyester having a hydroxyl group at the terminal is used, the degree of polymerization of the polyester increases.

Furthermore, when a polyester having carboxyl groups at the ends is used, the amount of carboxyl groups at the ends of the polyester decreases.

Normally, when polyester polymerization is carried out industrially, the resulting polyester often contains both hydroxyl groups and carboxyl groups as terminal groups.

In particular, when a polyester having a relatively high melting point is to be polymerized in a molten state, decomposition occurs simultaneously with the polymerization of the polyester as described above, resulting in a polyester having a relatively high concentration of terminal carboxyl groups.

When the method of the present invention is applied to such polyesters, it is possible to increase the degree of polymerization and lower the concentration of terminal carboxyl groups.

In this case, it is particularly preferable that the ratio of hydroxyl groups to carboxyl groups satisfies the following formula because the effect is significant.

Polyesters with a high degree of polymerization and an extremely low terminal carboxyl concentration are particularly valuable as industrial materials (for example, quill cords, belts, etc.), and according to the present invention, such polyesters can be easily produced as described above. .

In the present invention, the bislactam oxalate reacted with polyester has the general formula [wherein R and R' are divalent organic residues having no ester-forming functional group.

] This is a compound represented by

R2R' in the above general formula is specifically a polymethylene group such as a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, a nonamethylene group, a decamethylene group, and its alkyl substituent; For example, 3-methylpentamethylene group,
Examples include 3-ethylpentamethylene group.

Among these, those in which the ramtam ring forms a 5- to 7-membered ring are preferred because they exhibit particularly excellent effects.

In the present invention, a small proportion of bislactam oxalate is reacted with a molten polyester having an intrinsic viscosity of 0.15 or more.

Here, a small proportion means 0 to all end groups of polyester.
．． A range of 0.05 to 2 times the mole is appropriate, preferably 0.05 to 2 times the mole.
The amount is in the range of 1 to 1 times the mole, more preferably 0.1 to 0.5 times the mole.

Therefore, the amount of bislactam oxalate decreases as the degree of polymerization of the polyester increases, and increases as the degree of polymerization decreases.

The reaction temperature of the polyester and bislactam oxalate is higher than the melting point of the polyester, preferably 180-32
00C1 Particularly preferably 240 to 300°C.

If the temperature is too low, the reaction rate is slow and it is difficult to achieve the object of the present invention, and if the temperature is too high, the resulting polyester will be undesirably colored.

The reaction time may be within 1 minute, but is usually between 1 minute and 3 hours.

The reaction pressure may be Calo pressure, but when it is particularly desired to obtain a polyester with a high degree of polymerization, it is preferable to carry out the reaction under normal pressure or reduced pressure, for example, at an absolute pressure of 10 to 0.1 mmHg.

According to the present invention, there is an advantage that a polyester having a high degree of polymerization and a low content of terminal carboxyl groups can be easily obtained.

In the present invention, the intrinsic viscosity of polyester is determined from the solution viscosity measured at 35° C. after dissolving polyester in orthochlorophenol.

Next, the method of the present invention will be explained with reference to Examples.

Example 1 97g of dimethyl terephthalate, 6g of ethylene glycol
9 g of antimony trioxide, 0.04 g of calcium acetate hydrate, and 0.07 g of calcium acetate hydrate were charged into a rectification column and an autoclave equipped with a stirrer, and heated to 160 to 225°C to distill out methanol produced as a result of the transesterification reaction. .

After the transesterification reaction was completed, an equal mole of phosphoric acid was added to calcium acetate, and the transesterified product was transferred to a condensation polymerization reactor, and the internal temperature was raised to 265°C in a nitrogen stream for 30 minutes. The internal temperature was raised to 275° C. over a period of minutes, and during this time the pressure was gradually reduced to 0.3 mmHg.

Subsequently, a molding reaction was carried out for 60 minutes at 275° C. under reduced pressure of 0.3 mmHg absolute to obtain polyethylene terephthalate having an intrinsic viscosity of 0.58 and a terminal carboxyl group weight of 13 equivalents/106 g.

Here, the pressure of the reaction system was returned to normal pressure with nitrogen gas, and 1.4 g of biscaprolactam oxalate (1 mole more than all the acid components constituting polyethylene terephthalate, 0.5 mole more than all the terminal groups of polyethylene terephthalate) After stirring at normal pressure for 2 minutes, the absolute pressure was 0.
The molding reaction was carried out for 30 minutes under a reduced pressure of 3 mmHg.

The intrinsic viscosity of the obtained polyethylene terephthalate was 1.
15. The amount of terminal carboxyl groups was 6.5 equivalents/106g.

Comparative Example 1 Instead of biscaprolactam oxalate, 1.78 g of biscaprolactam terephthalate (1 mole based on all acid components constituting polyethylene terephthalate, 0.5 times mole based on all end groups of polyethylene terephthalate) is used. The polycondensation reaction of polyethylene terephthalate was carried out in the same manner as in Example 1 except for this.

The intrinsic viscosity of the obtained polyethylene terephthalate was 1.
20, but the amount of terminal carboxyl group was 17 equivalents/1
It was 06g.

Comparative Example 2 The same procedure as in Example 1 was carried out except that bislactam oxalate was not added, and the polycondensation reaction was carried out under reduced pressure of 0.3 mmHg absolute pressure for 90 minutes.

The intrinsic viscosity of the obtained polyethylene terephthalate was 0.
75, and the amount of terminal carboxyl groups was 16 equivalents/106 g.

Claims (1)

[Claims] 1. A method for producing a polyester, which comprises reacting a polyester having an intrinsic viscosity of 0.15 or more, containing an aromatic dicarboxylic acid as the main acid component and an aliphatic glycol as the main dihydroxy component, with bislactam oxalate in a molten state.