JPH04306225A - Production of heat resistant polyester having high polymerization degree - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant polyester having high polymerization degree and reduced in terminal carboxy groups. CONSTITUTION:A polyester such as polyethylene terephthalate is reacted with a carbodiimide compound and bislactam compound at a weight ratio of (3/1) to (1/3) and an amount of 0.2-3.0wt.% based on the polyester.

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 heat-resistant, highly polymerized polyester having a reduced number of terminal carboxyl groups.

0002

[Prior Art] Polyester such as polyethylene terephthalate has excellent physical properties and is inexpensive, making it an extremely useful material that can be used not only for textile purposes as a general-purpose polymer but also as a molding material. It is. However, when used at high temperatures, the terminal carboxyl group (hereinafter referred to as COOH) acts as a catalyst, inducing hydrolysis or amine decomposition, resulting in poor heat resistance.

[0003] For this reason, many means have been proposed for reducing the COOH of polyester. For example, a method has been proposed in which a carbodiimide compound is reacted with a polyester (Japanese Patent Publication No. 55-9091, etc.), but although this method does reduce COOH, it has the problem of lowering the degree of polymerization.

On the other hand, as a method for increasing the degree of polymerization of polyester, a method has been proposed in which polyester is reacted with a bislactam compound (Japanese Unexamined Patent Publication No. 48-55236). It mainly reacts and does not contribute to the reduction of COOH.

[0005]

SUMMARY OF THE INVENTION The present invention aims to provide a method for producing a highly polymerized polyester with improved thermal stability, which can reduce the COOH of polyester and simultaneously increase the degree of polymerization. It is something.

[0006]

[Means for Solving the Problems] The present invention solves the above problems, and its gist is to add a carbodiimide compound to a polyester consisting of an aromatic dicarboxylic acid component and a glycol component having 2 to 6 carbon atoms. A method for producing a heat-resistant highly polymerized polyester, characterized by adding and reacting a bislactam compound at a weight ratio of 3/1 to 1/3 and 0.2 to 3.0% by weight based on the polyester. be.

The present invention will be explained in detail below. The polyester in the present invention is obtained by a normal melt polycondensation reaction from an aromatic dicarboxylic acid component and a glycol component having 2 to 6 carbon atoms, and specifically polyester is polyethylene terephthalate, polytetramethylene terephthalate, polyethylene- Examples include 2,6-naphthalate, polyethylene isophthalate, and copolymers thereof. It should be noted that these polyesters may contain colorants, antistatic agents, matting agents, antioxidants, etc., as long as they do not impair processability.

[0008] The carbodiimide compound in the present invention is
It is expressed by the following general formula. R1-N=C=N-R2 (R1 and R2 are monovalent alicyclic or aromatic groups)

000
9] Specific examples of carbodiimide compounds include bis(2
-methylphenyl)carbodiimide, bis(2-isopropylphenyl)carbodiimide, bis(2-chlorophenyl)carbodiimide, bis(2-benzylphenyl)carbodiimide, bis(2-nitrophenyl)carbodiimide, bis(2,6-diethylphenyl) Examples include carbodiimide, bis(2,6-diisopropylphenyl)carbodiimide, 1,3-di-p-tolylcarbodiimide, dicyclohexylcarbodiimide, and the like.

Further, the bislactam compound in the present invention is represented by the following formula.

[0011]

[Chemical formula 1]

(R3 is a divalent aliphatic, alicyclic or aromatic group)

Specific examples of bislactam compounds include terephthaloyl-bis-N-caprolactam, isophthaloyl-bis-N-caprolactam, and adipoyl-bis-N-caprolactam.
Examples include N-caprolactam and sebacoyl-bis-N-caprolactam. Note that two or more of the carbodiimide compounds and bislactam compounds may be used in combination.

In the present invention, the carbodiimide compound mainly reacts with the COOH of the polyester to block the terminal groups, and the bislactam compound mainly reacts with the terminal hydroxyl group to increase the degree of polymerization. By simultaneously reacting these compounds with polyester, the CO of polyester can be removed without inhibiting each other's reactions.
It is possible to simultaneously reduce OH and increase the degree of polymerization.

In the present invention, the weight ratio of the carbodiimide compound and the bislactam compound is 3/1 to 1/1.
3, and the total amount of these compounds is
It must be added in an amount of 0.2 to 3.0% by weight based on the polyester. If the proportion of the carbodiimide compound is less than this range, the effect of reducing COOH will be poor, and if the proportion of the bislactam compound is less than this range, the effect of increasing the degree of polymerization of the polyester will be poor. Furthermore, if the amount of these compounds added is less than 0.2% by weight, a polyester with excellent thermal stability cannot be obtained;
On the other hand, if the amount added exceeds 3.0% by weight, the reaction will proceed satisfactorily, but gelation of the polyester will occur, which is not preferable.

The reaction between the polyester and the carbodiimide compound and bislactam compound is usually carried out at a temperature higher than the melting temperature of the polyester and for a period of 3 minutes or more. During the reaction, the atmosphere must be filled with an inert gas such as nitrogen gas, or active gases such as oxygen that promote the decomposition of polyester must be blocked by other methods, and the reaction must be carried out under stirring. It should be done.

The final shape of the polyester in the present invention may be fibers, films, or other molded products.

[0018]

[Examples] Next, the present invention will be specifically explained with reference to Examples. Note that the intrinsic viscosity of polyester is a value measured at a temperature of 20° C. using a mixture of equal weights of phenol and tetrachloroethane as a solvent.

Example 1 Polymer produced from terephthalic acid and ethylene glycol by a conventional method, with an intrinsic viscosity of 0.73 and a COOH of 106
Blending bis(2,6-diisopropylphenyl)carbodiimide (BDIPCI) and terephthaloyl-bis-N-caprolactam (TPBCL) in the weight ratio and addition amount shown in Table 1 with respect to 24 g equivalent of polyethylene terephthalate chips per g, Spinning was performed using a spinneret having 192 spinning holes with a diameter of 0.5 mm. The spinning conditions were a temperature of 300°C, a residence time of 5 to 15 minutes, and a discharge rate of 30.
0g/min, winding speed 317m/min, 8520d/min.
A 192f undrawn yarn was obtained. The obtained undrawn yarn was stretched 3.8 times at 90°C in the first stage, and 2x in the second stage.
The yarn was drawn 1.5 times at 00°C and then heat-treated under tension at 220°C to finally obtain a drawn yarn of 1500d/192f. The intrinsic viscosity and amount of COOH of the obtained drawn yarn were measured.

[0020] Also, using this drawn yarn, first 40T/
10cm Z twist, then 40T/1 after putting the two together
0 cm of S-twist processing was performed to make a raw cord of 1500 d x 2, immersed in a one-bath adhesive solution, and after applying a tension of 1.0 kg per cord, heat treatment was performed at 240 ° C. for 3 minutes to make a treated cord, The strength (initial strength) of the processing code was measured. Next, the treated cord was embedded in the rubber and heated at 170°C for 1
A sample for heat resistance strength measurement was prepared by vulcanization at 00 kg/cm2 for 60 minutes. A cord was extracted from this sample and its strength (heat resistance strength) was measured. In addition, the treated cord was embedded in the rubber, and the temperature was 150℃ and 100kg/
A sample for H-test was prepared by vulcanization at cm2 for 30 minutes. The adhesive strength of this sample was measured using the H-test. Each measurement value is numbered in Table 1. Shown in 1 to 6.

No. 1, which is an embodiment of the present invention. 1.No. 2
Then, as COOH decreases, the intrinsic viscosity increases,
The heat-resistant strength and heat-resistant strength retention rate were improved, and the adhesive strength also showed good values. On the other hand, No. 1, which does not contain any additives. 3
In this case, the intrinsic viscosity was low, an increase in COOH was observed, and the values of heat-resistant strength and heat-resistant strength retention were also low. No. 1, in which the amount of additives added is larger than the range of the present invention. In No. 4, gelation of the polymer occurred and spinning was impossible. In addition, No. to which only BDIPCI was added. In No. 5, although the COOH decreased, the intrinsic viscosity did not increase, and a high-strength cord could not be obtained. No. with only TPBCL added. In 6,
Although the intrinsic viscosity increased, the decrease in COOH was small, and the heat-resistant strength and heat-resistant strength retention were not improved.

Example 2 Dicyclohexylcarbodiimide (DCC) and isophthaloyl-bis-N-caprolactam (IPBCL) were added to the same polyethylene terephthalate chips as in Example 1.
and blended at a weight ratio of 1/1 and an addition amount of 0.6% by weight,
The same operation as in Example 1 was performed. The measured values are shown in Table 1.
7.

As in Example 1, as COOH decreased, the intrinsic viscosity increased, the heat-resistant strength and heat-resistant strength retention were improved, and the adhesive strength also showed good values.

[0024]

[Table 1]

[0025]

Effect of the invention: According to the present invention, COO of polyester
The degree of polymerization can be increased at the same time as H is decreased, and a polyester with extremely improved thermal stability, that is, resistance to hydrolysis and amine decomposition at high temperatures, can be produced. It improves performance in conventional applications, streamlines processes, and enables new applications in fields where it could not be applied before.

Claims (1)

[Claims] [Claim 1] An aromatic dicarboxylic acid component and a carbon number of 2 or more
A carbodiimide compound and a bislactam compound are added in a weight ratio of 3/1 to a polyester consisting of a glycol component (6).
~1/3 ratio of 0.2 to 3.0% to polyester.
A method for producing a heat-resistant highly polymerized polyester, which comprises adding 0% by weight and reacting.