KR870000472B1 - Preparation of high molecular polytetramethylene adipamide - Google Patents

Abstract

High molecular polytetramethylene adipamide is prepd. by condensation of prepolymer of polytetramethylene adipamide. Amount of the prepolymer-chain terminal group is less than 0.20mg equivalent per 1g of prepolymer. 0.5-15mole% of 1,4-diaminobutane is excessively used and the prepolymer contains water vapor. In the solid phase, the prepolymer is condensed to give polytetramethylene adipamide. The condensation is performed at 225-275≰C.

Description

Process for the preparation of polymer polytetramethylene adipamide

The present invention relates to a process for producing polymeric polytetramethylene adipamide by post-condensation of polytetramethylene adipamide prepolymer in a solid phase.

It is already known to produce polymer polyamides by postcondensation of low molecular weight polyamides at temperatures below the melting point and polymer nylon 6 or 6.6 can thus be produced.

Postcondensation is actually effective in an inert atmosphere without oxygen, so most of it is under the nitrogen atmosphere, atmospheric pressure or reduced pressure.

If the polymer nylon 4.6 is to be prepared by postcondensation reaction of the prepolymer in a solid state under vacuum or nitrogen, the desired polymer material will be obtained, but the polyamide will soon be discolored.

It is an object of the present invention to obtain a method for the postcondensation of nylon 4.6, in which a polymer material can be obtained without the above drawbacks.

The invention _{[NH- (CH 2) 4 -NH} -CO (CH 2) 4 -CO] by condensation and then the low molecular weight prepolymer consisting of units of _{[NH- (CH 2) 4 -NH} -CO (CH 2) 4 -CO] polymer white polyamide

In this way, a polymer white polyamide is produced. Polyamides are used to make materials such as films and filaments.

These are made by repeating injection molding, extrusion and melt spinning operations from solution.

Precisely prepared homopolymer polytetramethylene adipamide (nylon 4.6) has surprising properties and is well suited to making filaments and spinning materials.

The present invention is therefore intended to produce homopolymer nylon 4.6.

Copolyamides can also be made up of up to 20 parts by weight derived from compounds producing other polyamides and at least 80% by weight of units derived from adipic acid and 1.4-butane diamine.

Other forms of polyamide compounds are lactams such as caprolactam, valerolactam, undecalactam and laurolactam, amino acids such as succinic acid, cebacic acid, isophthalic acid and terephthalic acid. Amines such as carboxylic acids, gibbi and aromatic dicarboxylic acids, hexa merylenediamine or 1.4-aminomethyl cyclohexane.

Prepolymers contain adipic acid and 1.4-diamino moieties with excess 1.4-diaminobutane

The production of the prepolymer is effective if possible in an inert solvent. The molecular weight of the prepolymer will be between 1000-10000.

However, it is recommended that the prepolymer molecular weight be between 2000 and 6000.

Prepolymers that undergo condensation reactions in the form of solids are preferably small particles in which the particle size distribution is not too wide.

For example, the difference will be 1.0-1.5mm or 0.1-0.2mm.

The prepolymer must not discolor and must also have a relatively excessive amount of amino end groups.

The number of amino end groups must be at least equal to the sum of the carboxy end groups and at least equal to the sum of the other end groups.

Herein, another kind of terminal group means all terminal groups except for an amino terminal group and a carboxy terminal group.

In practice there is also a pyrrolidonyl end group produced by cyclization of diaminobutane or by cyclization of half of the diamino butane end chains upon polycondensation.

The amount of ring end groups of the prepolymer should not exceed 0.20 mg equivalents per gram of polymer, in fact prepolymers having large amounts of ring end groups can be converted to polyamides of the polymeric material.

Therefore, the amount of ring end groups should not exceed 0.15 mg per gram and more preferably not exceed 0.10 mg equivalent per gram.

The prepolymer can be converted to a polyamide of a polymeric material if the amount of the ring (pyrrolidinyl) end group is used in the preparation of the polyamide at a significant amount of diaminobutane at 0.10-0.15 mg equivalents per gram.

In addition, the prepolymer contains less than 0.10 mg equivalents per gram of the ring terminal group and is readily converted to a polyamide of the polymeric material if the proper balance of amino and carboxy terminal groups is achieved.

White polyamides are produced in all of the above by postcondensation of the white prepolymers in an atmospheric solid phase containing water vapor.

If there is an excess of diaminobutane, very little or absent in the prepolymer, no polyamide of the polymeric material is produced.

White polyamides of the polymeric material are produced only when there is an excess of diamine nobutane starting from the prepolymer.

This is surprising because the excess of diami as a result of the imbalance of amino and carboxyl groups leads to a decrease in molecular weight.

Excess 1.4 diaminobutane has already been added to the diamine-dicarboxylic acid salts from which the prepolymers are prepared by using an excess of diamine in the preparation of the salt or by adding an extra corresponding to the same moles of salt.

An excess of 0.5-15 mol% can be used by calculating the amount of 1.4 diaminobutane in moles such as dicarboxylic acid and it is better to use an excess of 1-5 mol%.

Postcondensation should be done in an atmosphere containing water vapor. Generally of water vapor

An atmosphere consisting solely of steam may be used and a base mixture consisting of at least 5% by volume free of water vapor or oxygen may be used.

Most suitable are mixtures of inert gases such as nitrogen and hydrogen containing 20-50% by volume of water vapor. Fixed gas phase may be used or gas may be passed through the reactor.

Pressure is less important for postcondensation but generally 0.001-10 bar is taken.

However, for practical and economic reasons, a pressure of about 1 bar may be used. Under reduced pressure, the reaction accelerates slowly.

Postcondensation is effective in the solid phase and will therefore be below the softening temperature of the polyamide. At least 200 ° C is preferred to limit the duration of the postcondensation.

The most suitable temperature is 225-275 ° C.

In order to obtain a homogeneous product, it is desirable to continuously move the polyamide particles during postcondensation.

To this end, this reaction must be carried out in a drum, in a fixed reactor with a stirrer, or in an expanded or isotropic phase.

The duration of the postcondensation depends on the desired molecular weight, temperature, molecular weight of the prepolymer and to some extent on pressure.

Thus, the number average molecular weight of the polyamide obtained under such conditions is between 15,000 and 75,000 and in detail 20,000 to 50,000. Duration of reaction at 250 ° C

To reduce the reaction time or make the polymer material in any limited time, start with a prepolymer containing an acid polymerization catalyst.

This catalyst is added before, after or during the production of the prepolymer. Most suitable catalysts are inorganic acids, in particular phosphoric acid, which have little or no volatility.

Prepolymers include additives such as pigments or matting agents so long as they do not interfere with postcondensation.

The addition of compounds such as hydrogen phosphide or phosphite to prevent discoloration during postcondensation is not necessary in the process according to the invention.

The invention is not limited to what is described herein but is explained in more detail in the following examples.

Example 1

The prepolymer is prepared by calculating the amount of adipic acid and heating a dry 1.4-diaminobutane adipic acid salt containing an excess of 5.4 mol% diamine in a pressure cooker from room temperature to 220 ° C. for 4 hours.

The pressure is then reduced, the reaction is cooled and taken out of the autoclave and collected into ones with an average particle size of 0.1-0.2 mm.

The number average molecular weight of this white prepolymer is 2,100 (relative viscosity is 1.24). The prepolymer undergoes a condensation reaction by heating at 250 ° C. for 4 hours while passing a vapor of 1 bar pressure in a flow form. Thus white polytetramethylene adip of molecular weight 15,400

The ultraviolet absorption detected by the 0.5% solution of formic acid at 290 nm is 0.023.

Example 2

The method is repeated and started with the same prepolymer but this time under reduced pressure.

Condensation reaction at a pressure of 0.066 bar yields a white polyamide having a molecular weight of 19,000 (relative viscosity of 2.72).

At 0.026 bar, a white polyamide having a number average molecular weight of 19,300 (relative viscosity of 2.80) is obtained.

Example 3 (Comparative Experiment)

The method of Example 1 was repeated and the condensation reaction was carried out using ammonia in the gaseous state starting from the same prepolymer but at 1 bar of atmospheric pressure to obtain a discolored product having a number average molecular weight of 6,100 (relative viscosity 1.61 ultraviolet absorption 0.10).

To repeat this experiment, use nitrogen gas to give a darkly discolored product.

Example 4

Dry 1.4-diaminobutane-adipic acid salt containing excess 9.5 mol% diamine is heated for 220 minutes from room temperature to a temperature of 212 ° C. at a pressure of up to 15 bar to obtain a prepolymer.

The prepolymer was heated in the same manner as in Example 1 as a fluid for 6 hours at 1 bar pressure and 260 ° C. while nitrogen and water vapor were passed through a 3: 1 volume gas mixture.

In this way, white polytetramethylene adipamide having a number average molecular weight of 25,500 is obtained.

Example 5

The prepolymer is subjected to the condensation reaction by the method described in Example 4, obtained by heating 1.4-diaminobutane-adipate containing an excess of 8 mol% diamine for 220 minutes at a pressure of 17 bar or less to 220 ° C.

A white polytetramethylene adipamide with a homogeneous molecular weight of 21,400 is obtained.

Example 6

The condensation reaction proceeds by the method described in Example 4, wherein a prepolymer is prepared by heating 1.4-diaminobutane-adipate containing excess 8 mol% diamine for 200 minutes at a pressure of 13 bar or less to 200 ° C.

White polytetramethylene adipamide having a number average molecular weight of 34,700 is obtained.

Example 7

The prepolymer is prepared by heating a dry 1.4-diaminobutane-adipic acid salt containing excess 8 mole% diamine and 0.1% phosphoric acid calculated to the total for 220 minutes at a pressure of 19 bar or less to 200 ° C.

Condensation reaction according to Example 4 yields white polytetramethylene adipamide having a number average molecular weight of 40,000.

Example 8

Pre-polymers are prepared by heating dry 1.4-diaminobutane-adipic acid salt with an excess of 1.3 mole-% diamine to 185 ° C. for 220 minutes at a pressure below 13 bar.

By proceeding the condensation reaction in the same manner as in Example 4, polytetramethylene adipamide having a number average molecular weight of 26,000 is obtained.

Example 9

The prepolymer is prepared by heating the 1.4-diaminobutaneadipic acid salt containing excess 2.1 mole-% diamine for 160 minutes to 195C at a pressure of 17 bar or less.

Condensation reaction was carried out in the same manner as in Example 4, and heating for 20 hours gave white polytetramethylene adipamide having a number average molecular weight of 41,900.

Example 10

The prepolymer molecular weight based on diaminobutane, adipic acid and 11-aminoundecanoic acid depends on the condensation reaction in the solid phase as described in Example I.

The physical data of the prepolymer and final product polyamide as well as the temperature and duration of the condensation reaction are shown in Table 1. Examples b, c, d, e, f and h relate to the prepolymers and polymers of Examples VI, IV, V, V, V and I, respectively.

TABLE 1

* Not according to the present invention

1.4 A prepolymer made of 80 parts by weight of diaminobutane-adipic acid salt, 1 part by weight of 11-aminoundecanoic acid and 10 parts by weight of water.

4.6Determination of Pyrrolidine End Groups in Nylon

Nitrogen is blown into a glass tube containing 0.25 g of dry polyamide and 0.5 ml of 6 normal hydrochloric acid, sealed, and heated to 130 ° C. in an oil bath.

This temperature is maintained until the polyamide is dissolved and then at that temperature for 4 hours. Cool the glass tube and open it when adipic acid crystals form.

Samples of gas chromatography analysis are obtained by diluting 0.2 ml of the supernatant to which 0.7 ml of 2 Norman alcohol sodium hydroxide solution is added.

The assay was carried out by taking 1 μl of a sample of 130 mm of a preconditioned 1.5 m × 1.41 / 4 '' chromosorb (RTM) heated to 150 ° C. for 1 minute and then to 13 ° C. per minute and to 220 ° C. Is carried out. Detection is performed by ion flame detection.

The pyrrolidine peak is detected after 4,5 minutes and the peak of 1.4-diamino butane is detected after 8 minutes.

The amount of diaminobutane of 5.6 nylon is 0.005 / mol g.

The pyrrolidine dose is calculated by the [pyr] = 5000 / peak ratio between the diaminobutane peak and pyrrolidine peak regions and is expressed as mmol pyrrolidine / g of polymer.

Claims (1)

Postcondensation of low molecular prepolymers composed of [NH- (CH ₂ ) ₄ -NH-CO- (CH ₂ ) ₄ -CO] units, and [NH- (CH ₂ ) ₄ -NH-CO- (CH ₂ ) ₄ -CO In preparing the polymer white polyamide composed of units, the amount of 1.4 diamino butane corresponding to adipic acid used is 0.5 in the range in which the amount of the terminal groups does not exceed 0.20 mg equivalent per gram of the prepolymer. A method for producing polytetramethyleneadipamide, wherein the prepolymer is used in excess of -15 mol% and the prepolymer is subjected to postcondensation in a solid phase in the air, including water vapor.