WO2022118557A1 - Polyamide manufacturing method and polyamide manufactured by said manufacturing method - Google Patents

Abstract

A polyamide manufacturing method for using a diamine and a polyester including a dicarboxylic acid component and a glycol component to manufacture, in a solid-phase state, a polyamide containing a dicarboxylic acid component and a diamine component, the polyamide manufacturing method being characterized in carrying out the following steps (I) to (III) in the sequence listed. (I) Adding a diamine and a polyester having a specific surface area of 100 cm2/g or above. (II) Performing heating and stirring under normal pressure and at a temperature of between (melting point of the diamine – 100°C) and (melting point of the diamine + 150°C). (III) Then further performing heating and stirring at a temperature equal to or higher than (boiling point of glycol having the highest boiling point from among the glycol components constituting the polyester – 50°C).

Description

Polyamide manufacturing method and polyamide manufactured by the manufacturing method

The present invention relates to a method for producing a polyamide by recycling the constituent components of polyester.

From the viewpoint of effective use of resources and from the viewpoint of controlling carbon dioxide emissions as a measure against global warming, many material recycling techniques are being studied.
The method of recycling resin materials is material recycling, in which the recovered waste resin is melted again and used, and the recovered waste resin is once decomposed into monomers and oligomers by a chemical reaction, and this decomposition product is used as a raw material for chemical recycling. It is roughly divided into three types: thermal recycling, which uses the recovered waste resin as a heat source.
Material recycling is widely used from the viewpoint of ease of recycling, but due to the effects of impurities and deterioration of resin, the material obtained by remelting can maintain the same performance as virgin material. There is the problem of being difficult.
Since chemical recycling decomposes into raw materials, the material obtained by repolymerization can have exactly the same performance as the virgin material, but it requires a complicated process, so it is cost effective. It is difficult to substitute for virgin material.
Due to these problems, waste resin that is thermally recycled is the most common at present, but it is an undesired method from the viewpoint of effective use of resources and carbon dioxide emissions. Therefore, there is a strong demand for the development of inexpensive chemical recycling technology.

Various recycling technologies have been developed for polyethylene terephthalate, which is widely used for beverage bottles. Among them, in the chemical recycling method, a technique of depolymerizing polyethylene terephthalate into bis-2-hydroxyethyl terephthalate and repolymerizing it has been developed. However, the polymerization of polyester needs to remove impurities and water as much as possible, and has a problem that a great cost is required to purify the depolymerization monomer.

On the other hand, a method for synthesizing polyamide from polyester and diamine has been developed. This synthetic method utilizes the aminolysis reaction of polyester with diamine, and this reaction is a reaction that is much easier to proceed than the polymerization of polyester.
Patent Document 1 proposes a method in which an aprotic sparse-protic polar solvent is added to polyester and diamine. Further, Patent Document 2 proposes a method of reacting polyester and diamine in supercritical water or subcritical water. Since both methods use a solvent, it is necessary to remove the solvent after the reaction, and the method of Patent Document 2 further requires high temperature and high pressure, so that the process cost becomes excessive.
Patent Document 3 proposes a method in which diamine is added to polyester in multiple stages and melt-kneaded. Since this method requires heating above the melting point of the aromatic polyamide, there is a concern about the generation of by-products and gelation.

Japanese Unexamined Patent Publication No. 11-106504 Japanese Unexamined Patent Publication No. 2004-83721 Japanese Unexamined Patent Publication No. 2001-11175

An object of the present invention is to provide a method for chemically recycling polyester constituents to produce polyamide under solvent-free and low-temperature conditions while suppressing process costs.

As a result of diligent research to solve the above problems, the present inventors heated and stirred polyester having a specific specific surface area and diamine, and found that polyamide was not used and was not heated to the melting temperature. We have found that the above-mentioned problems can be solved by synthesizing the above-mentioned problems, and have reached the present invention.
The method for producing a polyamide of the present invention is a method for producing a polyamide containing a dicarboxylic acid component and a diamine component in a solid phase state using a polyester containing a dicarboxylic acid component and a glycol component and a diamine. It is characterized in that the steps (I) to (III) are performed in this order.
(I) Polyester having a specific surface area of 100 cm ² / g or more and diamine are added to the reactor.
(II) Under normal pressure, heat and stir at (melting point of diamine -100 ° C) to (melting point of diamine + 150 ° C).
(III) After that, heating and stirring are further performed at a temperature of (the boiling point of glycol having the highest boiling point among the glycol components constituting the polyester −50 ° C.) or higher.
According to the method for producing a polyamide of the present invention, it is preferable to use polyethylene terephthalate as the polyester.
According to the method for producing a polyamide of the present invention, it is preferable to use a fibrous polyester.
According to the method for producing a polyamide of the present invention, it is preferable to use a powdery polyester.
According to the method for producing a polyamide of the present invention, it is preferable to use an aliphatic diamine having 6 to 12 carbon atoms.
According to the method for producing a polyamide of the present invention, it is preferable to use 1,10-decanediamine.
The polyamide of the present invention is produced by the above method.

According to the present invention, polyester can be chemically recycled under mild conditions, and can be upgraded to a polyamide having excellent performance such as heat resistance, hydrolysis resistance, and mechanical strength as compared with before recycling. A recycling method can be provided. Further, when decanediamine made of a plant-derived raw material is used as the diamine to be used, it is possible to provide a unprecedented sustainable resin material such as a biomass material and a recycled material.

Hereinafter, the present invention will be described in detail.
In the production method of the present invention, the raw material polyester may be used or discarded during the production process.
The polyester is not particularly limited as long as it contains a dicarboxylic acid component and a glycol component and has an ester bond in the molecule. For example, in the case of aromatic polyester, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate and the like can be mentioned. In addition, examples of the aliphatic polyester include polybutylene succinate and the like. Polyethylene terephthalate and polybutylene terephthalate are preferable because polyamides having excellent mechanical strength and the like can be obtained, and polyethylene terephthalate is particularly preferable because they are easily available as raw materials.

Further, the polyester may be a polyester obtained by copolymerizing another dicarboxylic acid component, a glycol component, an oxycarboxylic acid component, or the like with the components constituting the polyester, as long as the object in the present invention is not impaired. It may be a blend of the above-mentioned polyesters or a blend of the above-mentioned polyester and a copolymerized polyester.
Examples of the dicarboxylic acid component include isophthalic acid, naphthalenedicarboxylic acid, 5-sophthalosulfoisophthalic acid, phthalic acid anhydride, sebacic acid, adipic acid, succinic acid and the like, and the diol component includes other components that can be copolymerized. , Etandiol, propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol and the like.

In the present invention, the raw material polyester needs to have a specific surface area of 100 cm ² / g or more, preferably 500 cm ² / g or more, and more preferably 1000 cm ² / g or more. When the specific surface area of the polyester is 100 cm ² / g or more, the added diamine is adsorbed on the surface of the polyester at the same time even if it is melted by heating, so that the aminolysis reaction proceeds rapidly and adheres to the wall surface of the device. And it is possible to suppress the adhesion between polyesters. Further, the specific surface area of the raw material polyester is preferably 40,000 cm ² / g or less because the operability may decrease due to adhesion to the wall surface of the device or the like.

The shape of the polyester is not particularly limited as long as the specific surface area is within the above range, and it is preferably in the form of powders or fibers. The powdery material can be obtained by pulverizing polyester. The fibrous material may be cut to a length that can be put into the reaction device, or may be provided as it is without being cut.

In the production method of the present invention, the raw material diamine may be either an aliphatic diamine or an aromatic diamine, and the polyester glycol is produced from the viewpoint of efficiently removing the polyester glycol component produced by the reaction between the polyester and the diamine. Those having a boiling point higher than the boiling point of the component are preferable.
For example, when polyethylene terephthalate is used as the raw material polyester, it is particularly preferable to use a diamine having a boiling point higher than the boiling point of ethylene glycol (198 ° C.). Examples of such diamines include aromatic diamines having 6 to 20 carbon atoms, alicyclic diamines having 6 to 20 carbon atoms, and aliphatic diamines having 6 to 12 carbon atoms, such as hexamethylenediamine and 2-methyloctamethylene. Examples thereof include diamine, trimethylhexamethylenediamine, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane and 1,12-diaminododecane.
Among these, the diamine is preferably an aliphatic diamine having 8 to 12 carbon atoms, and particularly preferably 1,10-decanediamine, from the viewpoint of the balance between the melting point and the boiling point and the use after regeneration. .. Since 1,10-decanediamine is generally a plant-derived raw material, the polyamide 10T obtained by using this and polyethylene terephthalate has a diamine component as a biomass material and a dicarboxylic acid component as a recycled material. , It is a material with a very low environmental load.

The method of the present invention for producing a polyamide containing a dicarboxylic acid component and a diamine component is described in the following (I) in a solid phase state in which the polyester as a raw material and the polyamide as a reaction product are not melted by using the polyester and the diamine. )-(III) in this order.
(I) Polyester having a specific surface area of 100 cm ² / g or more and diamine are added to the reactor.
(II) Under normal pressure, heat and stir at (melting point of diamine -100 ° C) to (melting point of diamine + 150 ° C).
(III) After that, heating and stirring are further performed at a temperature of (the boiling point of glycol having the highest boiling point among the glycol components constituting the polyester −50 ° C.) or higher.

The reactor that can be used in the production method of the present invention is not particularly limited, but a device capable of uniformly stirring even a solid is preferable in order to maintain a solid phase state, that is, a solid (powder) state from beginning to end.

In the step (I), the amount of diamine to be blended in the polyester is preferably 1.00 to 1.50 mol with respect to 1 mol of the repeating unit of the polyester. If the blending amount of the diamine is less than 1.00 mol, the obtained polyamide becomes a copolymer in which the glycol component remains, and the physical properties may be deteriorated. On the other hand, if the blending amount of the diamine exceeds 1.50 mol, the diamine is excessive with respect to the dicarboxylic acid component of the polyester, and the obtained polyamide may not have a high degree of polymerization.

In step (II), heating and stirring are performed under normal pressure.
The temperature in step (II) needs to be (melting point of diamine −100 ° C.) to (melting point of diamine + 150 ° C.), and is from (melting point of diamine −50 ° C.) to (melting point of diamine + 150 ° C.). It is preferable, and it is more preferable that it is (melting point of diamine) to (melting point of diamine + 120 ° C.).
If the temperature in step (II) is lower than (melting point of diamine −100 ° C.), the reaction between diamine and polyester is difficult to proceed, and it becomes difficult to obtain polyamide. Further, when the temperature in the step (II) is higher than (melting point of diamine + 150 ° C.), the diamine is close to the boiling point, so that it is vaporized before reacting with polyester and is excluded from the system, so that the polyamide It becomes difficult to increase the molecular weight of.
Even if the temperature in step (II) is higher than the melting point of diamine, the polyester used in the present invention has a specific surface area of 100 cm ² / g or more, so that diamine is adsorbed on the polyester surface at the same time as melting, and the system as a whole Can maintain a solid phase state (solid state).

Following step (II), further heating and stirring is performed in step (III).
The temperature in the step (III) needs to be higher than (the boiling point of the glycol having the highest boiling point among the glycol components constituting the polyester −50 ° C.).
If the temperature in step (III) is lower than (the boiling point of glycol having the highest boiling point among the glycol components constituting polyester), the produced glycol component cannot be sufficiently removed, and the obtained polyamide is a dicarboxylic acid. It is a copolymer composed of an acid component, a diamine component, and a glycol component.
Further, the temperature in the step (III) is preferably 280 ° C. or lower. If the temperature in the step (III) is higher than 280 ° C., the polyamide may be gelled or the diamine component may be volatilized and discharged to the outside of the system, so that the degree of polymerization may not be increased.

The above steps (I) to (III) are performed in a substantially solid phase state. The method performed in the solid phase state is economically excellent because it does not require complicated equipment and does not require a step of removing a solvent or the like. However, if necessary, a step of washing the polyamide with a low boiling point solvent may be provided after step (III) for the purpose of removing reaction by-products. In that case, it is necessary to remove the cleaning solvent and dry the polyamide.

The method for producing a polyamide of the present invention is, if necessary, an antioxidant, an antioxidant, a flame retardant, a flame retardant, a heat stabilizer, a light stabilizer, a colorant, a lubricant, a reinforcing material, a filler, and a pigment. Etc. may be mixed and carried out.

By the above steps (I) to (III), a polyamide in which the glycol component of polyester is replaced with a diamine component can be obtained. The polyamide produced by the method of the present invention preferably has an amide group conversion rate represented by the ratio of amide bonds to total bonds of 90% or more, more preferably 95% or more, and more preferably 99% or more. It is more preferable to have.

The polyamide produced by the method of the present invention can be obtained by various molded products, films, sheets, fibers, etc. by a known method such as injection molding, extrusion molding, blow molding, compression molding, or by a known film forming method or spinning method. Can be processed into.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

1. 1. Measurement method The physical properties of polyamide were measured by the following method.

(1) Melting point Using a differential scanning calorimeter (DSC-7 type manufactured by PerkinElmer), the temperature was raised to 360 ° C at a temperature rise rate of 20 ° C./min, held at 360 ° C. for 5 minutes, and the temperature drop rate was 20 ° C./min. The temperature was lowered to 25 ° C., and the temperature was further maintained at 25 ° C. for 5 minutes, and then the top of the heat absorption peak when the temperature was raised again at a heating rate of 20 ° C./min was defined as the melting point (Tm).

(2) Amide group conversion rate Dicarboxylic acid by ¹ H-NMR analysis using a high-resolution nuclear magnetic resonance apparatus (ECA500NMR manufactured by Nippon Denshi Co., Ltd., resolution: 500 MHz, solvent: trifluoroacetic acid, temperature: 25 ° C.). The ratio of the amide bond to the total bond was calculated from each peak intensity area ratio derived from the component, the diamine component, the glycol component, the terminal carboxyl group, the terminal hydroxyl group, and the terminal amino group, and used as the amide group conversion rate. Since all the bonds are ester bonds before the reaction, the amide group conversion rate is 0%.

2. 2. Raw Materials The raw materials used in Examples and Comparative Examples are shown below.

(1) Polyester PET-1
Fiber waste discharged in the manufacturing process of polyethylene terephthalate (PET) fiber (fineness 3.0 dtex, density 1.38, specific surface area 1742 cm ² / g)
・ PET-2
Fiber waste discharged in the PET fiber manufacturing process (fineness 10.0 dtex, specific density 1.38, specific surface area 954 cm ² / g)
・ PET-3
The recovered PET bottle was cut into pieces of about 5 mm with scissors and then crushed by a crusher (volume average particle diameter 95 μm, specific density 1.38, specific surface area 458 cm ² / g).
・ PET-4
The recovered PET bottle was cut into 5 mm pieces with scissors (specific surface area 54 cm ² / g).

(2) Diamine / decanediamine (DDA, melting point 62 ° C, boiling point 260 ° C or higher)
Hexamethylenediamine (HMDA, melting point 42 ° C, boiling point 205 ° C)
Nonandinamine (NDA, melting point 37 ° C, boiling point 260 ° C)
Butane diamine (BDA, melting point 30 ° C, boiling point 160 ° C)

Example 1
6.00 g of PET-1 was weighed, and 1.10 mol of DDA was weighed with respect to 1 mol of the repeating unit of PET-1, and they were put into a reactor with a stirrer (step (I)).
Under a nitrogen atmosphere, step (II) was heated and stirred at 170 ° C. for 3 hours, and then step (III) was heated and stirred at 250 ° C. for 9 hours.
After completion of the reaction, the temperature was returned to room temperature, and the reaction product was taken out from the reactor to obtain a white polyamide powder.

Examples 2 to 7, Comparative Examples 1 to 3
The white polyamide powder was prepared in the same manner as in Example 1 except that the type of polyester, the type and amount of diamine, the temperature and time of step (II), and the temperature of step (III) were as shown in Table 1. Obtained.

Table 1 shows the results of measuring the polyamide production conditions, the melting point of the obtained polyamide, and the amide group conversion rate.

In Examples 1 to 7, the diamine melted at the initial stage of the reaction was immediately adsorbed on the polyester and then maintained in a dry solid state, and the obtained polyamide had a high amide group conversion rate.

In Comparative Example 1, since the specific surface area of the polyester was too low, the reaction with the diamine did not proceed efficiently, and in the step (II), the polyester was in a viscous state.
In Comparative Example 2, since the temperature in step (II) was too high, the diamine was vaporized, and the obtained polyamide had a low amide group conversion rate.
In Comparative Example 3, the temperature in step (III) was too low, so that the glycol component could not be sufficiently removed, and the obtained polyamide had a low amide group conversion rate.

Claims (7)

1. A method for producing a polyamide containing a dicarboxylic acid component and a diamine component in a solid phase state using a polyester containing a dicarboxylic acid component and a glycol component and a diamine, and the following steps (I) to (III). A method for producing a polyamide, which is characterized by performing in the order of.
   (I) Polyester having a specific surface area of 100 cm ² / g or more and diamine are added to the reactor.
   (II) Under normal pressure, heat and stir at (melting point of diamine -100 ° C) to (melting point of diamine + 150 ° C).
   (III) After that, heating and stirring are further performed at a temperature of (the boiling point of glycol having the highest boiling point among the glycol components constituting the polyester −50 ° C.) or higher.
2. The method for producing a polyamide according to claim 1, wherein polyethylene terephthalate is used as the polyester.
3. The method for producing a polyamide according to claim 1 or 2, wherein a fibrous polyester is used.
4. The method for producing a polyamide according to claim 1 or 2, wherein a powdery polyester is used.
5. The method for producing a polyamide according to any one of claims 1 to 4, wherein an aliphatic diamine having 6 to 12 carbon atoms is used.
6. The method for producing a polyamide according to any one of claims 1 to 4, wherein 1,10-decanediamine is used.
7. Polyamide produced by the method according to any one of claims 1 to 6.