KR100551950B1 - Method of producing heat-resistant polyamide resin - Google Patents

Abstract

A method of converting a polyester resin to a heat resistant polyamide resin using an amidation reaction is disclosed. Such a method for producing a polyamide resin includes a batch reaction step of reacting a polyester resin and a diamine compound in the presence of an organic solvent and an esterification reaction catalyst, and a semi-batch reaction step of polycondensing the batch reaction product while removing a glycol component. do. In a semibatch reaction, nitrogen gas may be forced into the reaction mixture to polycondense the batch reaction product while removing the glycol component.

Polyamide, Polyester, Amidation, Polycondensation, Catalyst, Nitrogen

Description

Method of producing heat-resistant polyamide resin             

1 is a graph showing the reaction conversion rate according to the reaction progress step in the amidation conversion reaction of polyethylene terephthalate according to embodiments of the present invention.

Figure 2 is an infrared spectral peak of the batch reaction product of the polyamide resin manufacturing process.

Figure 3 is a graph showing the weight loss according to the heating of polyamide, polyethylene terephthalate and polyparaphenylene terephthalamide prepared according to an embodiment of the present invention.

The present invention relates to a method for producing a heat resistant polyamide resin, and more particularly, to a method for converting a polyester resin into a heat resistant polyamide resin using an amidation reaction.

Polyester resin, typically polyethylene terephthalate (PET), is a thermoplastic resin used in a wide range of applications, such as bottles, packaging films, and fibers. One of the recycling methods for such polyester resins is waste It is converting polyester resin into polyamide resin.

An example of such a method of converting polyester resins to polyamides is disclosed in US Pat. No. 5,837,803. The method for preparing polyamides disclosed in U.S. Patent No. 5,837,803 first uses aliphatic or aromatic organic solvents as a reaction medium in a batch reaction system to about 0.5 to 1.5 moles of diamine compound per mole of polyester resin and polyester repeating unit. React. The product of this batch reaction has the form of a polyester-polyamide copolymer in which the ester group of the polyester is partially substituted with an amide group. In addition, the document described above, the reaction conversion rate from the ester group to the amide group by further performing a polycondensation reaction while maintaining the solid reaction product obtained through a reduced pressure drying process in a solid or molten state under reduced pressure after performing the batch reaction process as described above It can be said that it can be increased much more than the batch reaction step. In such a method for producing polyamide, the most important step for determining the physical properties and yield of the polyamide is a batch reaction, but the batch reaction disclosed in the literature is about 0.5 to 10 hours, in the examples usually 10 hours, at least 7 hours Since the above reaction time is required, the reaction process is not only very economical, but also a reaction catalyst for promoting such a batch reaction is not mentioned.

In addition, Japanese Patent Application Laid-Open No. 50-105914 discloses a polyamide which performs a transesterification reaction by dissolving polyethylene terephthalate in an organic solvent and then adding an excess of 5 to 15 moles of diamine compound based on 1 mole of polyester repeating units. A manufacturing method is disclosed. The document discloses that a metal acetate-based complex salt compound can be used as a reaction catalyst in the amidation reaction step, and the fiber obtained by melt spinning the reaction product obtained by the above method has a breaking strength, elastic modulus, and the like. Although mechanical properties are inferior, it is disclosed that the heat resistance is greatly improved from the weight loss curve characteristics with increasing temperature. However, this method has the disadvantage of using an excess of diamine compound, and further detailed effects of using a catalyst are not disclosed.

As described above, in the conventional polyamide preparation method, a semi-batch reaction is performed in which a polycondensation reaction is performed while removing a glycol component in order to increase the conversion rate of the amidation reaction after performing a batch reaction. In the semi-batch reaction, a high vacuum of 3 torr or less is applied to the reaction mixture of the solid phase or the melted phase in order to promote the evaporation and removal of glycol components such as ethylene glycol, which is produced as a by-product, so that the process conditions are not gentle and sufficient vacuum is not applied. In this case, the amidation reaction conversion rate is low. In addition, the methods do not specifically disclose a process for obtaining polyparaphenylene terephthalamide, which is a kind of wholly aromatic polyamide, using paraphenylene diamine as an aromatic diamine.

Accordingly, an object of the present invention is to provide a method for producing a heat resistant polyamide resin which can effectively recycle waste polyester resin.

Another object of the present invention is to provide a method for producing a polyamide resin capable of shortening the reaction time of a batch reaction for producing polyamide and improving the reaction yield.

It is still another object of the present invention to provide a method for preparing a polyamide resin capable of increasing the amidation conversion rate in a solid phase polycondensation semibatch reaction.

In order to achieve the above object, the present invention provides a batch reaction process for reacting a polyester resin and a diamine compound in the presence of an organic solvent and an esterification catalyst and a semi-batch reaction process for polycondensing the batch reaction product while removing a glycol component. It provides a method for producing a heat resistant polyamide resin comprising. Here, the polyester resin is polyethylene terephthalate, the diamine compound is paraphenylenediamine, the esterification catalyst is lithium hydroxide, calcium hydroxide, lithium hydride, calcium hydride, lithium aluminum hydride , Tetramethylammonium borohydride, lithium methoxide, calcium methoxide, lithium acetate, red acetate (Lead Acetate), calcium acetate, manganese acetate, zinc oxide, boron oxide and the like.

The present invention also provides a batch reaction step for reacting a polyester resin and a diamine compound in the presence of an organic solvent and a semi-batch reaction step for polycondensing the batch reaction product while removing a glycol component by forcing nitrogen gas into the reaction mixture. It provides a method for producing a heat resistant polyamide resin comprising a.

Hereinafter, the present invention will be described in detail.

The method for preparing a heat resistant polyamide resin according to the present invention is a batch process (first step, batch) in which a polyester resin and a diamine compound are reacted in the presence of an organic solvent and an esterification catalyst, and the batch reaction while removing a glycol component. A semibatch process (second stage, semi-batch) of polycondensation of the product is included.

As the polyester resin that can be used in the present invention, various aromatic or aliphatic polyesters can be used in a wide range of resins. Preferably, aromatic polyester resins are used, and most preferably polyethylene terephthalate can be used. In addition, various aliphatic or aromatic diamine compounds may be used as the diamine compound, preferably an aromatic diamine compound is used, and most preferably paraphenylenediamine is used. Thus, when polyethylene terephthalate is used as a polyester resin and paraphenylenediamine is used as a diamine compound, a polyester-polyamide copolymer is obtained, and finally, when the amidation reaction is carried out completely, it is a wholly aromatic polyamide. Polyparaphenylene terephthalamide is prepared, and the reaction process for each step is shown in Scheme 1 below.

Although the reaction conditions of the batch reaction are not particularly limited, typically the reaction temperature is 180 ℃ to 230 ℃, the reaction pressure is 7 kgf / ㎠ or more in nitrogen pressure, the amount of diamine is poly based on the polyester repeating unit 0.5 to 1.5 moles of diamine, preferably 0.9 to 1.1 moles per mole ester. Examples of the reaction solvent that can be used in the batch reaction include normal dodecyl benzene, dimethyl sulfooxide, sulfolane, diethyl ether, and the like. The solvent may be administered to the reaction system by 10 times or more in mass ratio based on the amount of diamine used. desirable.

In the present invention, a catalyst is used to shorten the reaction time of the batch reaction and to improve the reaction yield. As the catalyst used in the batch reaction, a transesterification catalyst used in polyester polymerization may be used, and specifically, lithium hydroxide, calcium hydroxide, lithium hydride, calcium hydride, lithium aluminum hydride, tetra Metal acetate complex salt compounds, such as methyl ammonium borohydride, lithium methoxide, calcium methoxide, lithium acetate, red acetate, calcium acetate, and manganese acetate, zinc oxide, boron oxide, etc. can be used individually or in mixture. The amount of the catalyst is preferably 0.001 to 0.1 moles per mole of polyester on the basis of the polyester repeating unit. If the amount of the catalyst is less than 0.001 mole, the reaction time may not be sufficiently shortened and the yield may not be sufficiently improved. When the amount exceeds 0.1 mole, the reaction time may not be shortened and the reaction yield improvement may not be obtained, and the physical properties of the resulting polyamide may be deteriorated.

During the batch reaction, the reaction mixture remains in a slurry state in which the polyester resin is not completely dissolved in the solvent. After carrying out a batch reaction for a predetermined reaction time, for example, 8 hours or more for a non-catalytic reaction without a catalyst, 1 hour or more, preferably 1 to 5 hours when a catalyst is administered, After the filtration and recovery, after washing several times with an excess of methanol or acetone and dried under reduced pressure at 120 ℃ for at least 24 hours to complete the batch (first step) reaction.

In the second stage batch reaction, the first stage batch reaction product is polycondensed while evaporating off a glycol component such as ethylene glycol which is a reaction byproduct. In the present invention, by forcing nitrogen gas into the reaction mixture more than a predetermined rate in the semi-batch reaction, it promotes the evaporation removal of glycol components such as ethylene glycol, a byproduct of the solid-phase polycondensation reaction, and greatly increases the conversion rate of amidation reaction Can be improved. Specifically, glycols produced as reaction byproducts by blowing nitrogen gas through the reaction mixture at a rate of at least 10 ml / min per 100 g of reactant, preferably at a rate of 10 to 40 ml / min, with appropriate stirring of the batch reaction product. The components can be easily discharged out of the reactor. At this time, when the inflow of nitrogen gas is less than 10 ml / min per 100 g of the reactant, the glycol component is not sufficiently removed, and when it exceeds 40 ml / min, it is impossible to keep the reaction temperature constant. There is a problem of outflow loss with the gas out of the reactor. Typically, the reaction time of the semi-batch reaction process is maintained for 5 hours or more.

Hereinafter, preferred embodiments of the present invention are described. However, the following examples are intended to illustrate the present invention, and the present invention is not limited to the following examples.

Example 1

In the first batch reaction, the reaction temperature is set at 210 ° C., the reaction pressure is set to 10 kgf / cm 2 by nitrogen pressure, and 1.0 mole of paraphenylenediamine per 1.0 mole of polyester based on the polyester repeating unit of polyethylene terephthalate. Was administered to the reaction. Normal dodecylbenzene was used as a reaction solvent, and the amount of solvent administered was 10 times or more by mass ratio compared to the amount of diamine used. After performing a batch reaction for 1 hour, the reaction product was filtered, recovered and washed, and then dried under reduced pressure at 120 ° C. for at least 24 hours to obtain a solid product. In the second semi-batch reaction, while stirring the reaction product obtained in the batch reaction step at a reaction temperature of 210 ℃, nitrogen gas was blown into the reaction mixture at a rate of more than 20ml / min per 100g of reactant to perform a solid phase polycondensation reaction, The semi-batch reaction lasted for at least 1 hour.

Example 2

The polyamide was carried out in the same manner as in Example 1, except that 0.015 mol red acetate per mol of the polyester was used as a catalyst for the batch reaction based on the polyester repeating unit. Was prepared.

Example 3

Using 0.015 mole of red acetate per mole of polyester as a reaction catalyst for a batch reaction based on a polyester repeating unit, and evaporating off the ethylene glycol produced as a reaction by-product of the solid phase polycondensation reaction in a semi-batch reaction. A polyamide was prepared by performing a batch reaction and a semi-batch reaction in the same manner as in Example 1, except that a reaction of about 200torr was added to the reaction system and the reaction continued for about 5 hours.

로 표시)에 나타내었다. 아마이드화율(Amidation Ratio: AR)은 폴리에스테르의 아마이드화 반응전환율에 대응되는 수치로서 적외선 분광 분석으로 얻어진 적외선 스펙트럼을 이용하여 AR = λ₁₅₄₀ / (λ₁₇₁₀ +λ₁₅₄₀)의 관계식으로부터 얻었으며, 여기서 λ₁₇₁₀ 과 λ₁₅₄₀은 각각 1710 cm^-1 및 1540 cm^-1에서 나타나는 적외선 특성 피크들의 흡수율(absorbance)이다. 또한 아마이드화 반응전환율을 간접적으로 나타내는 또 다른 수치인 반응 생성물에 함유되어 있는 질소 함량은 원소분석(Element Analysis)을 통하여 구하였다.The amidation ratio according to the reaction time and the nitrogen content included in the reaction product, the amidation ratio of the catalyst batch reaction of Example 2 and the nitrogen content included in the reaction product were measured. Table 1 and Figure 1 (Amidation Rate of Batch-Free Batch Reaction:

Indicated by). The amidation ratio (AR) is a numerical value corresponding to the amidation conversion rate of the polyester, and is obtained from the relation of AR = λ ₁₅₄₀ / (λ ₁₇₁₀ + λ ₁₅₄₀ ) using an infrared spectrum obtained by infrared spectroscopy. λ ₁₇₁₀ and λ ₁₅₄₀ are the absorbances of the infrared characteristic peaks appearing at 1710 cm ⁻¹ and 1540 cm ⁻¹ , respectively. In addition, the nitrogen content contained in the reaction product, which is another value indirectly indicating the amidation reaction conversion rate, was obtained through element analysis.

Non-catalytic reaction Catalysis Response time (hr) 0.5 One 5 10 15 20 One Amidation rate 0.370 0.489 0.570 0.589 0.600 0.596 0.587 Nitrogen content (wt.%) 4.4 4.0 8.4 10.2 9.1 9.2 9.6

From Table 1 and Figure 1, in the case of a non-catalyzed batch reaction, the reaction equilibrium is reached after 10 hours or more, the amidation rate, which corresponds to the reaction conversion rate is about 0.589, the nitrogen content contained in the reaction product It can be seen that is about 10.2 wt%. On the other hand, when red acetate was used as a catalyst, the reaction was carried out for 1 hour, which was much shorter than the reaction time of the non-catalytic reaction process, thereby obtaining 0.587 amidation rate and 9.6 wt% of nitrogen. It can be seen that.

및

로 표시). When nitrogen was circulated in a batch reaction without using a catalyst in a batch reaction (Example 1), when a catalyst was used in a batch reaction and circulated in a nitrogen reaction in a batch reaction (Example 2), and in a batch reaction. In the case of using the catalyst in the reaction, and the nitrogen was not circulated in the semi-batch reaction (Example 3) and the nitrogen content contained in the reaction product was measured and shown in Table 2 below, the semi-batch of Examples 1 and 2 The amidation rate after the reaction is shown in FIG. 1 (each,

And

Displayed).

Reaction step Response time (hr) Amidation rate Nitrogen content (wt.%) No catalyst catalyst No catalyst catalyst Batch Reaction (Slurry State) One 0.489 0.587 4.0 9.6 Semi-batch reaction (solid state) (Method-I) forced circulation of nitrogen gas One 0.557 0.612 6.5 10.4 5 0.702 0.744 8.5 11.9 10 0.711 0.770 8.5 11.1 Application example Example 1 Example 2 Example 1 Example 2 (Method-II) Vacuum part One - 0.615 - 7.5 5 - 0.653 - 8.9 Application example Example 3 Example 3

As can be seen from Table 2 and FIG. 1, in the noncatalytic reaction of Example 1, the amidation rate after the batch reaction for 1 hour was 0.489, and the amidation rate for the half batch reaction was 0.557 (1 hour) and 0.702 (5 hours). ) And 0.711 (10 hours), and in the catalytic reaction of Example 2, the amidation rate after the batch reaction of 1 hour was 0.587, and the amidation rate was 0.612 (1 hour), 0.744 in the semibatch reaction. (5 hours) and 0.770 (10 hours) increase with time, and it can be seen that the amidation rate is higher than that of Example 1. Therefore, it can be seen that performing the catalyst batch reaction of about 1 hour and the semi-batch reaction of about 5 hours in steps can increase the amide reaction conversion of the polyester most effectively. In addition, it can be seen that the forced nitrogen gas circulation method (Example 2) is more effective than the vacuum addition method (Example 3) as a means for evaporating and removing the reaction byproduct ethylene glycol in the semi-batch reaction.

FIG. 2 is a graph for calculating the amidation rate, showing infrared spectroscopic peaks of polyethylene terephthalate, a non-catalyzed batch reaction product (reaction time: 1 hour and 10 hours), and a catalyst batch reaction product (reaction time: 1 hour). shows the (ester group = 1710cm ^-1, amide group = 1640 & 1540 cm ^-1). It can be seen from FIG. 2 that the polyester is converted to polyamide by reaction with paraphenylenediamine.

3 is polyethylene terephthalate (PET), a reaction product (1) of a batch reaction (1 hour) using a catalyst, and then a reaction product obtained by carrying out a semi-batch reaction (Example 2, reaction time: 1 hour, 5 hours And 10 hours, denoted by ②, ③, ④, and polyparaphenylene terephthalamide (“Kevlar” fibers), respectively. Weight loss is to compare the heat resistance of the conversion product from polyester to polyamide, and was measured using a thermogravimetry (TGA). From Figure 3 it can be seen that by applying a batch reaction and a semi-batch reaction step by step in order to convert the polyester to polyamide, it can be seen that the heat resistance is significantly higher than the polyester.

As described above, the production method of the heat-resistant polyamide resin according to the present invention can shorten the reaction time of the batch reaction for producing polyamide, improve the reaction yield, and in the solid-phase polycondensation semi-batch reaction Since the conversion rate of the amidation reaction can be further increased, the waste polyester resin can be efficiently recycled.

Claims (8)

A batch reaction process for reacting a polyester resin with a diamine compound in the presence of an organic solvent and an esterification catalyst, and A method for producing a heat-resistant polyamide resin comprising a semi-batch reaction step of polycondensing the batch reaction product while removing a glycol component. The method of claim 1, wherein the polyester resin is polyethylene terephthalate and the diamine compound is paraphenylenediamine. The method of claim 1, wherein the organic solvent is selected from the group consisting of normal dodecyl benzene, dimethyl sulfooxide, sulfolane, diethyl ether, and mixtures thereof. The method of claim 1, wherein the esterification catalyst is lithium hydroxide, calcium hydroxide, lithium hydride, calcium hydride, lithium aluminum hydride, tetramethylammonium borohydride, lithium methoxide, calcium methoxide , Lithium acetate, red acetate, calcium acetate, manganese acetate, zinc oxide, boron oxide, and a mixture thereof. The method of claim 1, wherein the amount of esterification catalyst used is 0.001 to 0.1 moles per mole of polyester based on the polyester repeating units. The method of claim 1, wherein the semi-batch reaction process is carried out while introducing nitrogen gas into the reaction mixture. The method of claim 6, wherein the inflow rate of nitrogen gas is 10 to 40 ml / min per 100 g of the reactant. Batch reaction process for reacting a polyester resin and a diamine compound in the presence of an organic solvent, and A method for producing a heat-resistant polyamide resin comprising a semi-batch reaction step of forcing nitrogen gas into a reaction mixture to polycondensate the batch reaction product while removing a glycol component.

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