WO2009079886A1

WO2009079886A1 - A semiaromatic polyamide and the preparation method thereof

Info

Publication number: WO2009079886A1
Application number: PCT/CN2008/000009
Authority: WO
Inventors: Min Cao; Shiyong Xia; Xianbo Huang; Xiangbin Zeng; Xiangan Luo; Zhenguo Shi; Jian Chen
Original assignee: Kingfa Science & Technology Co., Ltd.; Shanghai Kingfa Science & Technology Co., Ltd.
Priority date: 2007-12-14
Filing date: 2008-01-02
Publication date: 2009-07-02
Also published as: CN101456949A; CN101456949B

Abstract

A semiaromatic polyamide and the preparation method thereof. The semiaromatic polyamide of the present invention is manufactured as follows: producing an amide salt of high purity by neutralization reaction of aromatic dicarboxylic acids and aliphatic diamines with 4-14 carbon atoms in an organic solvent; carrying out prepolymerization of the amide salt of high purity in the presence of water; and subjecting the resulted prepolymer to further polymerization.

Description

Semi-aromatic polyamide and preparation method thereof

The present invention relates to the field of polyamide resin technology, and in particular to a method for preparing a semi-aromatic polyamide.

Background technique

Aliphatic polyamides, such as PA6, PA66, have excellent mechanical strength, heat resistance, chemical resistance, abrasion resistance and self-lubricity, and have low friction coefficient. Applications include electronics, automotive parts, furniture. , building materials and fiber, has become one of the most important engineering plastics.

The semi-aromatic polyamide is a polyamide resin prepared by polycondensation of a diamine or a dicarboxylic acid having an aromatic ring and an aliphatic dicarboxylic acid or a diamine, and is one of aromatic polyamides. Since the aromatic ring is introduced into the main chain of the polyamide molecule, the heat resistance and mechanical properties are improved, the water absorption rate is lowered, and the suitable performance/price ratio is obtained, which is between the general engineering plastic nylon and the high temperature resistant engineering plastic. A resin with high heat resistance between PEEK, mainly used in the automotive and electrical electronics industries. With the rapid development of high technology: its applications have new breakthroughs and progress, and market demand is on the rise. Semi-aromatic polyamide products currently mainly include polyamide MXD6, 6T/66, 6Τ/6Ι, 6Τ/6Ι/66, 6Τ/Μ-5Τ and 9Τ.

The preparation of polyamide MXD6 is disclosed in the patents JP57200420, JP58111829, EP1074585A, CN1624021A. In the proposed method, an aromatic diamine is added dropwise to the molten aliphatic dicarboxylic acid in a batch reactor while the temperature of the system is raised to remove the water formed by the condensation to carry out a polymerization reaction. CN1451677A describes a polyamide MXD6 solid phase thickening method, the polyamide is preserved under specific conditions, even if the starting polyamide is used for 20 days or more from the preparation to the solid phase thickening, the prepared polyamide MXD6 has a low yellowness. .

Since the melting point of polyamide 6T is higher than its decomposition temperature, a third monomer must be added to lower the melting point. The polyamide 6T copolymer is obtained by polycondensation of a dicarboxylic acid component mainly composed of terephthalic acid and isophthalic acid or adipic acid, and a diamine component mainly composed of 1,6-hexanediamine. The polyamide 6T copolymer has a high amide group concentration, which results in poor chemical resistance, water absorption resistance, and melt processing stability of the polymer. The addition of a large amount of the third monomer lowers the crystallinity of the polymer, and also causes a decrease in heat resistance, chemical resistance, water absorption resistance, and dimensional stability of the polymer.

U.S. Patents 5,158,882, 5,981,692 and US 962,628 describe terephthalic acid, isophthalic acid, 1,6-hexanedioic acid, 1,6-hexanediamine and 2-methyl-1,3-pentanediamine as main raw materials. A method of synthesizing a polyamide 6T copolymer by high-temperature melt polymerization at 300 ° C or higher. Patent US 6,140,459 describes the synthesis of a polyamide 6T copolymer by melt polymerization using terephthalic acid, 1,6-hexanediamine and another aliphatic long chain dicarboxylic acid as starting materials. However, when the semi-aromatic polyamide is prepared by melt polymerization, the late polymerization temperature exceeds the melting point of the polymer, and the residence time is too long at high temperature, and various side reactions and degradation reactions of the polymer are severe, which tends to cause the color tone of the polymer to change. Poor, mechanical strength is reduced and moldability is deteriorated.

No. 5,663,284 discloses a process for preparing a polyamide 6T/66 polymer by first carrying out primary polymerization in the presence of water at a reaction temperature below the melting point of the polymer, and maintaining it by replenishing water into the autoclave during discharge. Pressure, prepolymer through vented twin screw The extruder melts and thickens to obtain a high viscosity polymer. However, in order to obtain a prepolymer which satisfies the requirements for melt thickening, the prepolymerization temperature is close to the melting point of the polymer to increase the intrinsic viscosity of the prepolymer.

In the prior art, the patent US Pat. No. 6,133,406 proposes a polymerization process of a semi-aromatic polyamide: first synthesizing a low-viscosity prepolymer at a lower temperature in the presence of water, and then viscosifying the solid phase by solid phase The reaction prepares a prepolymer having a higher intrinsic viscosity, and is further thickened by twin-screw melt extrusion to obtain a polymer having a high intrinsic viscosity. This route involves prepolymerization, solid phase viscosification, melt viscosification and multi-step reactions, requiring complex production steps and equipment.

In the patent US6156869, after obtaining the prepolymer, the polyamide 9T resin can be obtained by long-term solid phase thickening, which requires the prepolymer to have a high intrinsic viscosity. Polyamide 9T has high crystallinity, dimensional stability and low water absorption.

In the prior art, a semi-aromatic polyamide prepolymer having a higher intrinsic viscosity can be obtained by increasing the prepolymerization temperature or discharging water in the prepolymerization system. Increasing the prepolymerization temperature leads to the occurrence of side reactions, which also increases the reaction pressure and increases the requirements on the equipment. Exhausting the water in the reaction system volatilizes the unreacted diamine, resulting in a large difference between the monomer unit ratio of the prepolymer and the starting monomer charged to the reactor, and the monomeric dicarboxylic acid cannot be guaranteed. The molar ratio of the diamine is balanced.

By first making the salt into a salt and then polycondensing the salt into a semi-aromatic polyamide, the loss of the diamine can be avoided. Patent US5663284 determines the end point of the salt formation reaction by measuring the pH value, and uses a salt to prepare a semi-aromatic polyamide.

In the synthesis of an aliphatic polyamide, in order to facilitate control of the molar ratio of the dicarboxylic acid, the diamine, and to remove impurities in the monomer, it is usually used to form a salt and then carry out a polycondensation reaction. Method. Preparing aliphatic polyamide salt, in through the first _reward; neutralization reaction solvent such as water or alcohol, followed by separation, purification and drying to obtain.

However, there is a problem in the prior art that when a semi-aromatic polyamide salt is prepared by using water or an alcohol as a solvent, the solubility of the aromatic dicarboxylic acid and the semi-aromatic polyamide salt in these solvents is very high. Small, purified semi-aromatic polyamide salt becomes difficult, it is difficult to obtain pure semi-aromatic polyamide salt, and then can not accurately control the molar ratio of dicarboxylic acid and diamine, affecting the final product semi-aromatic polymerization The quality of the amide.

Summary of the invention

The object of the present invention is to provide a method for preparing a semi-aromatic polyamide which solves the problem of the prior art and which uses a salt of high purity to accurately control the molar ratio of the dicarboxylic acid to the diamine. To avoid the loss of diamines, and to purify the monomers through the salt formation process, improve the quality of the semi-aromatic polyamide, and obtain semi-aromatic polyglybs with high intrinsic viscosity, high crystallinity, high melting point and good mechanical properties. Amide.

The above object of the present invention is solved by the following technical solutions:

A method for preparing a semi-aromatic polyamide, comprising the following steps -

(1) An aromatic dicarboxylic acid and an aliphatic diamine having 4 to 14 carbon atoms are dissolved in an organic solvent, and after completely neutralizing the reaction, the mixture is centrifuged, and the precipitate is washed to obtain a semi-aromatic polyamide. Salt; The molar ratio of the aromatic dicarboxylic acid to the aliphatic diamine having 4 to 14 carbon atoms is 1:1.

(2) prepolymerizing the above semi-aromatic polyamide salt as a raw material in the presence of water;

(3) The prepolymer obtained above is passed through a solid phase viscosity increasing reaction or a melt thickening reaction. Semi-aromatic polyamide.

The aliphatic diamine having 4 to 14 carbon atoms in the above step (1) includes a linear aliphatic diamine, a branched aliphatic diamine or an alicyclic diamine. Wherein the linear aliphatic diamine includes 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, U0-decanediamine, 1, 11-edecyldiamine or 1,12-dodecadiamine. Branched aliphatic diamines include 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,4-dimethyl-1,6-hexanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine or 5 —Methyl-1,9-nonanediamine. The alicyclic diamine includes cyclohexanediamine, methylcyclohexylamine or 4,4,diaminodicyclohexylmethane. The semi-aromatic polyamide salt may contain one or more types of these aliphatic diamines, and the preferred aliphatic diamines are 1,6-hexanediamine, 1,9-nonanediamine, 1,10- Diamine, 2-methyl-1,5-pentanediamine, 2-methyl-1,8-octanediamine or 5-methyl-1,9-decanediamine. The most preferred aliphatic diamine is 1,6-hexanediamine, 1,9-nonanediamine or 1,10-decanediamine.

The aromatic dicarboxylic acid in the above step (1) includes terephthalic acid, isophthalic acid, 2-methylterephthalic acid, 2,5-dichloroterephthalic acid, 2,6-nai Formic acid, 1,4 -nadicarboxylic acid, 4,4'-diphenylene or 2,2'-diphenyl. The semi-aromatic polyamide salt may contain one or more types of these aromatic dicarboxylic acids. Preferred aromatic dicarboxylic acids are terephthalic acid, isophthalic acid or 4,4'-diphenyl phthalic acid. The most preferred aromatic dicarboxylic acid is terephthalic acid.

The organic solvent in the above step (1) is N-methylpyrrolidone or dimethylformamide, and the organic solvent can dissolve the aromatic dicarboxylic acid and the aliphatic diamine, but is insoluble. Since the polyamide salt is solved, the resulting semi-aromatic polyamide salt can be easily separated and purified.

The prepolymerization in the above step (2) is carried out by adding a semi-aromatic polyamide salt, deionized water, a blocking agent and a catalyst to an autoclave, and the reaction temperature of the prepolymerization is 200 to 280 ° C, and the reaction system pressure is 1 ~5 MPa, the reaction time is 1 to 6 hours, and the pressure is stabilized by discharging water in the system later in the reaction. Among them, the preferred reaction temperature is 220 to 250 ° C; the optimum reaction time is 2 to 4 hours; and the preferred reaction system pressure is 1.5 to 3 MPa. By the prepolymerization, a prepolymer having an intrinsic viscosity [η] of 0.06 to 0.3 dl/g, preferably 0, 08 to 0.2 dl/g, which is measured in 96% sulfuric acid at 25 °C, can be obtained.

The catalyst includes phosphoric acid, phosphorous acid, hypophosphorous acid or a salt thereof or an ester thereof, preferably sodium phosphate, sodium phosphite, sodium hypophosphite, potassium phosphite. The amount of the catalyst was 0.01 to 2 by weight. /. Preferably, it is 0.05 to 1% by weight.

The blocking agent includes a monocarboxylic acid or a monoamine or a mixture thereof. Among them, monocarboxylic acids are preferred because monocarboxylic acids are less toxic, less volatile, and easier to handle than monoamines; monocarboxylic acids include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, and neopentyl Acid, isobutyric acid, heptanoic acid, octanoic acid, citric acid, lauric acid, stearic acid, etc.; alicyclic monocarboxylic acids such as cyproterone carboxylic acid, cyclopentanyl acetic acid, cyclohexanecarboxylic acid, etc.; Carboxylic acids such as benzoic acid, p-methylbenzoic acid, o-methylbenzoic acid, p-tert-butylbenzoic acid, salicylic acid, p-methoxybenzoic acid, phenylacetic acid, cinnamic acid and the like. The blocking agent may be one or more of them. The most preferred monocarboxylic acid is acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, benzoic acid or phenylacetic acid. Monoamines include aliphatic monoamines such as ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, isobutylamine, n-amylamine, n-decylamine, dodecylamine, stearylamine, etc.; One Amine such as cyclohexylamine; aromatic monoamine such as benzene: amine p-toluidine, o-toluidine, 2,6-dimethylaniline, 3,4-dimethylaniline, o-ethylaniline, and the like. The blocking agent may be one or more of them. The most preferred monoamine is ethylamine, n-propylamine, n-butylamine, aniline or p-toluidine. The molar amount of the blocking agent is from 0.2 to 10%, preferably from 0.5 to 5%, based on the semi-aromatic polyamide salt. Because when the amount of the blocking agent is too high, the molecular weight of the polymer is too small; when the amount of the blocking agent is too low, the molecular weight of the polymer is too large or the active end group content of the polymer is too large.

The amount of deionized water added in the initial stage of the prepolymerization in the above step (2) is 15 to 35 wt%. Because if the amount of water added is too small, the material will solidify during the polymerization process, the reaction will not proceed, and the product cannot be discharged from the reactor; if the amount of water added is too large, the polymerization rate will decrease, and the obtained prepolymerization will be obtained. The viscosity of the intrinsic property is also lowered, and the viscosity-increasing reaction cannot be carried out smoothly. In order to increase the reaction speed and the intrinsic viscosity of the prepolymer, a large amount of water is discharged during the polymerization, which inevitably leads to serious loss of the diamine and destruction of the monomer. Molar ratio.

The thickening of the prepolymer in the above step (3) can be achieved by a solid phase thickening reaction or a melt thickening reaction, and among them, a solid phase thickening method is preferred. The solid phase thickening is carried out below the melting point of the polymer, and the preferred reaction temperature is 22 () to 280 ° C, and the solid phase viscosity increasing reaction time is 3 to 20 hours, preferably 5 to 15 hours; The solid phase viscosity-increasing reaction is carried out under a nitrogen atmosphere or under vacuum, preferably under a nitrogen atmosphere. The advantage of solid phase thickening is that the reaction temperature is low, the degradation reaction is small, and the obtained polyamide has good color tone, dimensional stability, and heat resistance. Melt thickening is carried out on an extrusion device with a vent; the melt thickening temperature is higher than the melting point of the prepolymer, and the preferred reaction temperature is 290 to 350 ° C; The viscosity-increasing reaction time is 1 to 8 minutes, and is selected to be ~6 minutes. The advantage of melt thickening is that the reaction time is short. After the viscosity-increasing reaction, the final product semi-aromatic polyamide is obtained.

The semi-aromatic polyamide obtained by the invention has an intrinsic viscosity [η] of 0.8 to 2.5 dl/g, preferably 1.0 to 2.0 dl/g; a terminal carboxyl group content of 15 to 80 mol/t, preferably 15 to 50 mol/t; The amino group content is 15 to 80 mol/t, preferably 15 to 50 mol/t; and the melting point is 270 to 330 ° C, preferably 290 to 330 ° C. The reason for this range is preferred: when the melting point is too low, the heat resistance of the polyamide is less than that required by the present invention; and when the melting point is too high, a degradation reaction occurs during hot working.

本 Compared with the prior art, the present invention has the following beneficial effects: 1. The semi-aromatic polyamide of the present invention is prepared by first obtaining a high-purity semi-aromatic polyamide salt in an organic solvent to avoid semi-aromatic polyamide. The loss of diamine can accurately control the molar ratio of dicarboxylic acid to diamine, obtain polyamide with high intrinsic viscosity, and purify the monomer through salt formation process, and improve semi-aromatic polyamide. Melting point, crystallinity and mechanical properties.

2. The semi-aromatic polyamide prepared by the invention has high crystallinity, intrinsic viscosity and heat-resistant temperature, good hue, low content of active end groups, good processing stability and no corrosion of the mold. Antioxidants, lubricants, nucleating agents, flame retardants, colorants, plasticizers, antistatic agents may be added as needed; or may be enhanced by adding glass fibers, carbon fibers, inorganic fillers; Other polymers are blended to prepare a polymer alloy. detailed description

The invention is described by way of examples, without restricting the invention. The properties in the examples and comparative examples were measured in the following manner.

1. Characteristic viscosity [η] The logarithmic ratio of the polyamide of the concentration ^/Q, 05. 0.1, 0.3 and lg/dl was measured in concentrated sulfuric acid at 25" C. The viscosity η _{ίιΛ was measured} .

ΚΚ [1η( )]/'.

Where ri _inh represents the logarithmic viscosity (dl/g), to represents the solvent flow time (sec), ^ represents the sample solution flow time (sec), and C represents the sample solution concentration (g/dl) .

The data of T] _inh is extrapolated to a concentration of 0 to obtain the intrinsic viscosity [η] of the sample.

2. Terminal amine content

The amine content of the sample end was titrated by a fully automatic potentiometric titrator. 0.5 g of the polymer, 45 ml of phenol and 3 ml of anhydrous methanol were added, and the mixture was heated under reflux. After the sample was completely dissolved, it was cooled to room temperature, and the amine group content was titrated with a standard hydrochloric acid standard solution.

3. Terminal carboxyl content

The carboxyl group content of the sample was titrated by a fully automatic potentiometric titrator. Take 0.5g of polymer, add 50ml of o-cresol, dissolve at reflux, quickly add 400 L of formaldehyde solution after cooling, and titrate the terminal carboxyl group with the calibrated KOH-ethanol solution.

4. Melting point and heat of fusion

The melting point and heat of fusion of the sample were tested using a Perkin Elmer DSC-6 analyzer with a nitrogen atmosphere at a flow rate of 40 mL/min. During the test, first raise the temperature to 340 ° C at 10 ° C / min, hold at 340 ° C for 2 min, then cool to 50 ° C at 10 ° C / min, then raise the temperature to 34 (TC, 10 ° C / min, The endothermic peak temperature at the time is set to the melting point Tm, and the heat of fusion A Hm is calculated from the endothermic peak area at this time.

5. Crystallinity Determination of crystallinity of the polymer by X-ray diffraction method ₉ The molten polymer was quenched with liquid nitrogen to prepare an amorphous sample, and the X-ray diffraction peak areas of the amorphous sample and the polymer sample were respectively s^ns ₂ , The crystallinity is calculated by the following formula.

X _c =(S ₂ -S,)/S ₂ x 100

Wherein X _e represents crystallinity (:%), 8, represents an X-ray diffraction peak area of the amorphous sample, and S ₂ represents an X-ray diffraction peak area of the polymer sample.

6. boiling water dissolved content

Take 50g of semi-aromatic polyamide resin, dry in a vacuum oven at 80 ° C for 24 hours, completely remove the moisture contained in it, then put it into a 500ml glass flask, add 350ml of deionized water, and reflux at 100 ° C for 24 hours. .

After cooling, the extract was filtered, washed first with deionized water and then with isopropyl alcohol to wash the resin. The obtained filtrate was placed in an evaporating dish, dried under vacuum, the volatile solvent was removed, and the weight of the nonvolatile matter was weighed. The boiling water dissolved content is calculated by the following formula

Boiling water dissolved content (./^2)^/]^ X 100

Wherein Mi represents the weight of the semi-aromatic polyamide resin initially added, and M ₂ represents the weight of the nonvolatile matter.

7. Tensile strength and elongation at break

The prepared semi-aromatic polyamide was injection molded into a bell-shaped spline, and its tensile strength and elongation at break were tested in accordance with ASTM standards.

Example 1

16.61 Kg of terephthalic acid (100 mol) and 40 Kg of dimethylformamide were uniformly mixed, and heated to 120 ° C with stirring to form a solution A; 17.23 Kg of 1,10-decanediamine was further added. (lOOmol) mixed with 20Kg of dimethylformamide, combined with both sides. Stirring and heating to 80'C, made

B solution; Mix A solution and B solution uniformly, heat to 1?0 ° C, while stirring constantly, make the reaction sufficient; after centrifugation, the obtained precipitate is washed with dimethylformamide first. It was washed several times with deionized water to obtain 32.28 Kg of a terpene terephthalate salt, a yield of 95.4%, and a melting point of 260° (:.

In a 20L autoclave equipped with a magnetic coupling agitation, a condenser, a gas phase port, a feed port, and a pressure explosion port, 6769 g (20 mol) of yttrium terephthalate salt, 73.27 g (G.6 mol) of benzoic acid, 6.77 were added. g (0.1% by weight based on the total weight of the raw materials) Sodium hypophosphite, 22S3g

(Based on the total weight of the reaction system, it is 25 parts by weight of deionized water, and the temperature is raised after purging with nitrogen. The temperature is raised to 220 ° C in 2 hours under stirring, and the reaction mixture is stirred at 220 ° C for 1 hour, and then stirred under stirring. The temperature of the reactant was raised to 230 ° C. The reaction was continued at a constant temperature of 230 ° C and a constant pressure of 2 MPa for 2 hours, and the pressure was kept constant by removing the formed water, and the reaction was completed and discharged to obtain characteristics. The prepolymer was dried under vacuum at 80 ° C for 24 hours, and then solid phase viscosified at 260 ° C for 10 hours to obtain a PA10T resin having a melting point of 0.014 g/g. 321 °C, heat of fusion 72.7J / g, intrinsic viscosity [η] is] 43dl / g, terminal amine content is 37mol / t, terminal carboxyl content is 4}: moi / t, boiling water dissolved content 0.07 ° / The tensile strength was 82 MPa, and the elongation at break was 8%. The results are shown in Table 1. Example 2 The preparation procedure of Example 1 was repeated, except that the thickening method was changed to melt thickening, and the viscosity increasing temperature was 33 (TC). , tackifying time 5 minutes. The results are shown in Table 1.

Example 3 The raw materials of the same preparation procedure as in Example 1 were repeated and changed to terephthalic acid, isophthalic acid and 1J 0-decanediamine to prepare a terpene terephthalate salt and a phthalic acid diamine salt. .

5754 g (17 mol) of cerium terephthalate diamine salt and 1015 g (3 mol) of cerium diamine isophthalate were prepolymerized and viscosified, and the procedure was the same as in Example 1. The results are shown in the table.

Example 4

The preparation procedure of Example 1 was repeated, except that the starting materials were changed to terephthalic acid, 1,10-diamine, and 5-methyl-i,9-nonanediamine, thereby obtaining a terpene terephthalate salt. And 5-methyl-1,9-nonanediamine salt of terephthalic acid.

5754 g (17 mol) of cerium terephthalate diamine salt and 1015 g (3 mol) of 5-methyl-methyl hexamethylenediamine terephthalate were prepolymerized and viscosified, and the procedure was the same as in Example 1. . The results are shown in Table 1.

Example 5

The preparation procedure of Example 1 was repeated, except that the raw materials were changed to terephthalic acid, isophthalic acid and 1,6-hexanediamine, thereby preparing hexamethylenediamine terephthalate and isophthalic acid. Amine salt.

3388 g (12 mol) of hexamethylenediamine terephthalate and 2259 g (8 mol) of hexamethylenediamine isophthalate were subjected to prepolymerization and viscosity-increasing reaction, and the procedure was the same as in Example 1. The results are shown in Table 1. Example 6 The preparation step of Example 1 was repeated; the difference was that the starting materials were changed to terephthalic acid, 1,6-hexanediamine and 2-methyl-1,5-pentanediamine to obtain terephthalic acid. Diamine salt and 2-methyl-1,5-pentanediamine salt of terephthalic acid.

3388 g (12 mol) of hexamethylenediamine terephthalate and 2259 g (8 mol) of 2-methyl-1,5-pentanediamine terephthalate were prepolymerized and viscosified, and the procedure was the same as in Example 1. . The results are shown in Table 1.

Table 1 Example data results

Comparative example 1 Example 1 was repeated, and the different i was changed from hydraulic to 6849 g (50% by weight based on the total weight of the reaction system). The results are shown in Table 2.

Comparative example 2

Example 1 was repeated except that the raw material was changed to 3323 g (20 mol) of terephthalic acid and 3446 g (: 20 mol) of decanediamine, and terephthalic acid and decanediamine were directly subjected to a prepolymerization reaction. The results are shown in Table 2.

Comparative example 3

Example 1 was repeated except that the starting material was changed to 2824 g (17 mol) of terephthalic acid, 498 g (3 mol) of isophthalic acid and 3446 g (20 mol) of decyl diamine, and terephthalic acid, isophthalic acid and hydrazine were added. The diamine is directly subjected to a prepolymerization reaction. The results are shown in Table 2.

Comparative example 4

Example 1 was repeated except that the raw materials were changed to 3323 g (20 moi) of terephthalic acid and 3515 g (20.4 mol) of decanediamine, and terephthalic acid and decanediamine were directly subjected to prepolymerization. The results are shown in Table 2.

Comparative example 5

Repeat the example! The difference is that the raw materials are changed to 1994g (12mol) of terephthalic acid, 1329g (8mol) of isophthalic acid and 2324g (20mol) of hexamethylenediamine, and the terephthalic acid, isophthalic acid and hexamethylenediamine are directly processed. Prepolymerization. The results are shown in Table 2. Table: i compares the number of turns

^3⁄4 Direct prepolymerization with aliphatic diamines and aromatic dicarboxylic acids

Claims

Claim

A method for preparing a semi-aromatic polyamide, which comprises the following steps:

(1) An aromatic dicarboxylic acid and an aliphatic diamine having 4 to 14 carbon atoms are dissolved in an organic solvent, and after completely neutralizing the reaction, the mixture is centrifuged, and the precipitate is washed to obtain a semi-aromatic polymerization. Amide salt

(2) pre-polymerizing anti-S using the above semi-aromatic polyamide salt as a raw material in the presence of water;

(3) The prepolymer obtained above is subjected to a solid phase thickening reaction or a melt thickening reaction to obtain a semi-aromatic polyamide.

The method according to claim 1, wherein the aliphatic t-amine is a species of a linear aliphatic diamine, a branched aliphatic diamine or an alicyclic diamine or Several mixtures.

The method according to claim 2, wherein the linear aliphatic guanidine diamine is 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-diamine, 1,10-diamine, 1,11-undecalamine or 1,12-dodecadiamine; the branched aliphatic diamine is 2-methyl 1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,4,-dimethyl-1,6-hexanediamine, 2,2,4-trimethyl-1 ,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine or 5-methyl-1,9-nonanediamine The alicyclic diamine is cyclohexyldiamine, methylcyclohexanediamine or 4,4,diaminodicyclohexylformamidine.

4. The preparation method according to claim 1, wherein the aromatic dicarboxylic acid in the step (1) is terephthalic acid, isophthalic acid, 2-methylterephthalic acid, 2,5-dichloroterephthalic acid, 2,6 nebidex, 1,4-nadicarboxylic acid, 4,4'-diphenylene or 2,2'-diphenyl acid.

The method according to claim 1, wherein the organic solvent in the step (1) is N-methylpyrrolidone or dimethylformamide.

6. The preparation method according to claim 1, wherein the prepolymerization in the step (2) is carried out by adding a semi-aromatic polyamide salt, deionized water, a blocking agent, and a catalyst to an autoclave. Reaction, reaction temperature is 200~280'C, reaction system pressure 〖~. 5 pa, - .3⁄4 should be timed for 16 hours, the water in the system is discharged later to keep the pressure stable; the amount of deionized water is the whole reaction system 'i5 to 35 wt%, the amount of the catalyst is 0.01 to 2% by weight of the semi-aromatic polyamide salt, and the molar amount of the blocking agent is 0.2 to 10% of the semi-aromatic polyacrylamide salt.

The preparation method according to claim 6, wherein the catalyst is money: acid, phosphorous acid, hypophosphorous acid or a salt thereof or an ester thereof; the blocking agent is a monocarboxylic acid or a mono- or a mixture thereof .

The method according to claim 7, wherein the catalyst is sodium phosphate, sodium phosphite, sodium hypophosphite, potassium phosphite; the monocarboxylic acid is acetic acid, propionic acid, butyric acid, lauric acid. And stearic acid, benzoic acid or phenylacetic acid; the monoamine is ethylamine, n-propylamine, n-butylamine, aniline or p-toluidine.

The preparation method according to claim 1, wherein the solid phase thickening reaction in the step (3) is carried out under a nitrogen atmosphere or under a vacuum condition, and the reaction temperature is 220 to 280 ° C. The time is 3 to 20 hours; the melt thickening reaction is carried out on an extrusion apparatus with a vent, the reaction temperature is 290 to 350 ° C, and the reaction time is 1 to 8 minutes. The semi-aromatic polyamide obtained by the production method according to claim 1.

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