Method for producing adipic acid, hexamethylenediamine hydrochloride and polyhexamethylene (di)guanidine chloride from nylon-66 through depolymerization

Abstract

The invention discloses a method for producing adipic acid, hexamethylenediamine hydrochloride and polyhexamethylene (di)guanidine chloride from waste nylon-66 serving as a raw amerial through depolymerization, which is characterized by comprising the following steps of: depolymerizing the waste nylon-66 by using hydrochloric acid to obtain refined adipic acid and hexamethylenediamine hydrochloride; polymerizing the hexamethylenediamine hydrochloride and dicyandiamide (in a molar ratio of 1:1) at the temperature of between 170 and 190DEG C for 1 to 3 hours to obtain a white or pale yellow solid polyhexamethylene diguanidine chloride; and adding dicyandiamide and ammonium chloride powder in a molar ratio of 1:2 into a reactor, performing reaction at high temperature for 1 to 3 hours, slowly adding hexamethylenediamine hydrochloride powder, continuously reacting for 3 to 7 hours to obtain a white or pale yellow solid polyhexamethylene guanidine chloride. The method improves production efficiency, reduces production cost, and solves the problems of difficult separation of the product hexamethylenediamine due to depolymerization, low yield and poor benefit; and the technological process is environment-friendly, simple and convenient, and is suitable for industrial production.

Description

Technical field

[0001] The present invention relates to a new method for producing adipic acid, hexamethylene diamine hydrochloride and polyhexamethylene mono(bi)guanidine hydrochloride disinfectant by using nylon-66 waste depolymerization, and especially introduces a new method suitable for industrial production A new method for polyhexamethylene mono(bi)guanidine hydrochloride. Background technique

[0002] Nylon-66 is a polymer material made by polycondensation of adipic acid and hexamethylene diamine. During its synthesis and processing, unqualified products and scraps will be produced. At the same time, various nylon 66 products are difficult to handle after being used, which not only causes waste, but also pollutes the environment. Therefore, the recycling of waste nylon-66 has aroused widespread concern in society. How to turn it into a treasure and play its economic and social benefits has become a research focus. At present, the main methods of nylon recycling include...

Examples

Embodiment 1

[0027] (1) Depolymerization section: Add 1500Kg of 30% industrial by-product hydrochloric acid to the reactor equipped with reflux condenser and hydrochloric acid gas absorption device at the top, add 500Kg of water, heat, and add 1000Kg of waste nylon-66 fragments while stirring. The reaction temperature is controlled at 100-110°C, normal pressure, and time is 8 hours, the reaction conversion rate reaches more than 90%, and the acid hydrolysis solution is obtained. The acid hydrolysate is filtered and pressed into the crystallization tank through the coarse filter, and the cooling and crystallization speed is accelerated by pumping air at the top. The liquid entrained in the air pumping process is defoamed and collected in the external screen filter buffer tank, and passed into the jacket Circulate cooling water until the temperature of the crystallization tank drops to 30-40°C. After the crystallization is completed, the crude adipic acid crystals and the crude hexamethylened...

Embodiment 2

[0032] The depolymerization section (1), the adipic acid refining section (2) and the hexamethylene diamine hydrochloride refining section (3) are the same as in Example 1.

[0033] (4) In the polyhexamethylene mono(bi)guanidine hydrochloride preparation section, put the dicyandiamide and ammonium chloride powder with a molar ratio of 1:2 into the reactor, protect it with nitrogen, stir for 25min, and heat up to 180℃ , Stir the reaction for 2 hours, slowly add the hexamethylene diamine hydrochloride powder obtained in the hexamethylene diamine hydrochloride refining section (3), continue the reaction for 5 hours to obtain a mixture of polyhexamethylene monoguanidine hydrochloride and ammonium chloride, While hot, use nitrogen to slowly press the molten reaction liquid into a separation tank containing industrial ethanol, stir well and filter, and distill off the ethanol filtrate of polyhexamethylene monoguanidine hydrochloride under reduced pressure to obtain a light yellow color....

Embodiment 3

[0035] The depolymerization section (1), the adipic acid refining section (2), the hexamethylene diamine sulfate refining section (3), and the polyhexamethylene mono(bi)guanidine sulfate preparation section (4) are the same as in Example 2.

[0036] Add 300Kg of hot water (80±5°C) to the crude ammonium chloride white powder obtained after the above filtration, stir to dissolve and filter, concentrate under reduced pressure and evaporate until crystals just precipitate out, cool, filter, and vacuum dry to obtain 150Kg of refined sulfuric acid Ammonium solid, the yield is over 86%. According to the reaction equivalent ratio, fresh ammonium chloride is appropriately supplemented and reused to the polyhexamethylene mono(bi)guanidine hydrochloride preparation section (4).

[0037] The general molar ratio herein means that the molar ratio is allowed to fluctuate by 10% on the basis of equivalent reaction.

Technical field

[0001] The present invention relates to a new method for producing adipic acid, hexamethylene diamine hydrochloride and polyhexamethylene mono(bi)guanidine hydrochloride disinfectant by using nylon-66 waste depolymerization, and especially introduces a new method suitable for industrial production A new method for polyhexamethylene mono(bi)guanidine hydrochloride. Background technique

[0002] Nylon-66 is a polymer material made by polycondensation of adipic acid and hexamethylene diamine. During its synthesis and processing, unqualified products and scraps will be produced. At the same time, various nylon 66 products are difficult to handle after being used, which not only causes waste, but also pollutes the environment. Therefore, the recycling of waste nylon-66 has aroused widespread concern in society. How to turn it into a treasure and play its economic and social benefits has become a research focus. At present, the main methods of nylon recycling include...

Examples

Embodiment 1

[0027] (1) Depolymerization section: Add 1500Kg of 30% industrial by-product hydrochloric acid to the reactor equipped with reflux condenser and hydrochloric acid gas absorption device at the top, add 500Kg of water, heat, and add 1000Kg of waste nylon-66 fragments while stirring. The reaction temperature is controlled at 100-110°C, normal pressure, and time is 8 hours, the reaction conversion rate reaches more than 90%, and the acid hydrolysis solution is obtained. The acid hydrolysate is filtered and pressed into the crystallization tank through the coarse filter, and the cooling and crystallization speed is accelerated by pumping air at the top. The liquid entrained in the air pumping process is defoamed and collected in the external screen filter buffer tank, and passed into the jacket Circulate cooling water until the temperature of the crystallization tank drops to 30-40°C. After the crystallization is completed, the crude adipic acid crystals and the crude hexamethylened...

Embodiment 2

[0032] The depolymerization section (1), the adipic acid refining section (2) and the hexamethylene diamine hydrochloride refining section (3) are the same as in Example 1.

[0033] (4) In the polyhexamethylene mono(bi)guanidine hydrochloride preparation section, put the dicyandiamide and ammonium chloride powder with a molar ratio of 1:2 into the reactor, protect it with nitrogen, stir for 25min, and heat up to 180℃ , Stir the reaction for 2 hours, slowly add the hexamethylene diamine hydrochloride powder obtained in the hexamethylene diamine hydrochloride refining section (3), continue the reaction for 5 hours to obtain a mixture of polyhexamethylene monoguanidine hydrochloride and ammonium chloride, While hot, use nitrogen to slowly press the molten reaction liquid into a separation tank containing industrial ethanol, stir well and filter, and distill off the ethanol filtrate of polyhexamethylene monoguanidine hydrochloride under reduced pressure to obtain a light yellow color....

Embodiment 3

[0035] The depolymerization section (1), the adipic acid refining section (2), the hexamethylene diamine sulfate refining section (3), and the polyhexamethylene mono(bi)guanidine sulfate preparation section (4) are the same as in Example 2.

[0036] Add 300Kg of hot water (80±5°C) to the crude ammonium chloride white powder obtained after the above filtration, stir to dissolve and filter, concentrate under reduced pressure and evaporate until crystals just precipitate out, cool, filter, and vacuum dry to obtain 150Kg of refined sulfuric acid Ammonium solid, the yield is over 86%. According to the reaction equivalent ratio, fresh ammonium chloride is appropriately supplemented and reused to the polyhexamethylene mono(bi)guanidine hydrochloride preparation section (4).

[0037] The general molar ratio herein means that the molar ratio is allowed to fluctuate by 10% on the basis of equivalent reaction.

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