HK1188237B - Method for producing polyamide resin - Google Patents

Description

Method for producing polyamide resin

Technical Field

The present invention relates to a method for producing a polyamide resin.

Background

Polyamide resins produced from diamines and dicarboxylic acids are widely used in various fields. As a method for producing such a polyamide resin, a method of first preparing a nylon salt (polyamide salt) using a diamine and a dicarboxylic acid and polymerizing the nylon salt under pressure is generally used.

However, when a polyamide resin is produced by polymerizing a nylon salt under pressure, it takes a relatively long time to achieve a practical molecular weight. As a result, triamine is generated as a by-product in the polyamide resin, which causes gelation. When polymerizing a nylon salt under pressure, it is necessary to set the apparatus for polymerization to a standard for the pressure. Therefore, there is a problem that the cost for introducing the pressurization standard device and maintaining and managing the device is increased.

In order to solve the above-mentioned problems, it has been studied to polymerize a nylon salt under normal pressure. For example, JPH 03-243623A describes a polyamide resin obtained by polymerizing a nylon salt obtained from 1, 12-diaminododecane and a dicarboxylic acid in equimolar amounts under normal pressure.

However, the method for producing JPH 03-243623 a is limited to the polymerization of a nylon salt of dicarboxylic acid and 1, 12-diaminododecane, and is a technique that can be achieved only when the boiling point of 1, 12-diaminododecane is as high as 304 ℃. On the other hand, when a nylon salt obtained from a dicarboxylic acid and a diamine having a boiling point of 300 ℃ or lower is polymerized by the method described in JPH 03-243623A, the diamine volatilizes from the reaction system, and the molar balance between the diamine and the dicarboxylic acid contained in the nylon salt is lost. Therefore, the obtained polyamide resin does not have a high molecular weight, and is not suitable for practical use.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a method for producing a high-molecular-weight polyamide resin with reduced generation of by-products.

The present inventors have conducted intensive studies to solve such problems. As a result, they have found that a polyamide resin having a high molecular weight can be obtained and the present invention has been achieved by the fact that a nylon salt is polymerized while heating the nylon salt at normal pressure in the presence of steam in the polymerization reaction system and distilling off water to the outside of the system, whereby the polymerization time is shortened and the amount of by-products is reduced.

That is, the gist of the present invention is as follows:

(1) a method for producing a polyamide resin, characterized by heating a nylon salt obtained from a dicarboxylic acid and a diamine having a boiling point of more than 100 ℃ in the presence of water vapor in the system under normal pressure.

(2) The process for producing a polyamide resin according to (1), characterized in that 0.5 to 10 parts by mass of water per 100 parts by mass of the nylon salt is preliminarily present in the system at the start of heating.

(3) The process for producing a polyamide resin according to (1), wherein water vapor is allowed to flow through the system at the start of heating.

(4) The method for producing a polyamide resin according to any one of (1) to (3), wherein at least one diamine selected from the group consisting of 1, 10-diaminodecane, 1, 11-diaminoundecane, and 1, 12-diaminododecane is used.

(5) The process for producing a polyamide resin as described in any one of (1) to (4), wherein the diamine is not distilled out of the system during the heating.

(6) The process for producing a polyamide resin as described in any one of (1) to (5), wherein water is distilled out of the system while refluxing the water into the system.

According to the production method of the present invention, the polymerization time is shortened by polymerizing the nylon salt under normal pressure as compared with the case of polymerizing under pressure, and the amount of triamine as a by-product is small, that is, a polyamide resin with suppressed gelation can be obtained. Further, since polymerization is carried out under normal pressure, a standard pressurization apparatus is not required, and the cost for introducing the standard pressurization apparatus and maintenance management of the apparatus becomes inexpensive.

Further, the diamine having a boiling point of more than 100 ℃ is used, and polymerization is carried out while water vapor is present in the system, so that the diamine contained in the nylon salt can be suppressed from distilling out of the system during the polymerization reaction. As a result, the molar balance between the dicarboxylic acid and the diamine contained in the nylon salt can be maintained, and a polyamide resin having a high molecular weight can be obtained.

In addition, when the polymerization is carried out while distilling water out of the system while refluxing water into the system, the decomposition of the produced polyamide resin to produce a dicarboxylic acid and a diamine can be further suppressed, and therefore the polymerization reaction of the produced polyamide resin can be further promoted.

Detailed Description

The present invention will be described in detail below.

The method for producing a polyamide resin of the present invention is characterized by heating a nylon salt obtained from a dicarboxylic acid and a diamine having a boiling point of more than 100 ℃ in the presence of water vapor in the system under normal pressure.

In order to obtain the nylon salt used in the production method of the present invention, examples of the dicarboxylic acid include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids. Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid. Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Among them, as the dicarboxylic acid, terephthalic acid, isophthalic acid, and adipic acid are preferable from the viewpoint of general versatility.

In the nylon salt, the total ratio of terephthalic acid, isophthalic acid, and adipic acid to the total amount of the dicarboxylic acid components is preferably 70 mol% or more, and more preferably 90 mol% or more.

The diamine used for obtaining the nylon salt used in the production method of the present invention needs to be a diamine having a boiling point of more than 100 ℃, preferably a diamine having a boiling point of more than 150 ℃, more preferably a diamine having a boiling point of more than 200 ℃. By using a diamine having a boiling point of more than 100 ℃, the diamine is distilled out of the system without being preferentially volatilized to water in the polymerization reaction of the nylon salt, and the molar balance between the dicarboxylic acid and the diamine is not collapsed. As a result, a polyamide resin having a high molecular weight can be obtained. Further, the larger the difference between the boiling points of water and the diamine (i.e., the higher the melting point of the diamine), the more the diamine is distilled out of the system, and it is possible to easily distill only water out of the system.

As the diamine having a boiling point of more than 100 ℃, the following compounds can be mentioned: that is, 1, 2-diaminoethane (boiling point 117 ℃ C.), 1, 3-diaminopropane (boiling point 140 ℃ C.), 1, 4-diaminobutane (boiling point 159 ℃ C.), 1, 5-diaminopentane (boiling point 179 ℃ C.), 1, 6-diaminohexane (boiling point 204 ℃ C.), 1, 7-diaminoheptane (boiling point 224 ℃ C.), 1, 8-diaminooctane (boiling point 240 ℃ C.), 1, 9-diaminononane (boiling point 258 ℃ C.), 1, 10-diaminodecane (boiling point 271 ℃ C.), 1, 11-diaminoundecane (boiling point 282 ℃ C.), 1, 12-diaminododecane (boiling point 304 ℃ C.), 1, 4-cyclohexanediamine (boiling point 197 ℃ C.), o-phenylenediamine (boiling point 284 ℃ C.), m-phenylenediamine (boiling point 283 ℃ C.), p-phenylenediamine (boiling point 267 ℃ C.), p-xylylenediamine (boiling point 262 ℃ C.), m-xylylenediamine (boiling point 248 ℃ C.), and the like. Among them, 1, 10-diaminododecane, 1, 11-diaminoundecane, and 1, 12-diaminodecane are preferable from the viewpoint of increasing the difference in boiling points between water and diamine.

Examples of the polyamide resin obtained by combining the above-mentioned monomers (dicarboxylic acid and diamine) include polyamide 6T, polyamide 9T, polyamide 10T, polyamide 6I, polyamide 9I, polyamide 10I, polyamide 46, polyamide 66, and polyamide 610. Here, T represents terephthalic acid, and I represents isophthalic acid.

The method for obtaining the nylon salt from the dicarboxylic acid and the diamine is not particularly limited, and a known method can be used. For example, an aqueous solution method, a liquid method, a solid method, and the like can be given.

The aqueous solution method is a method of preparing an aqueous solution containing a dicarboxylic acid, a diamine and water, reacting the dicarboxylic acid and the diamine in the aqueous solution, and then cooling the aqueous solution to obtain a nylon salt. This method is the most common method for obtaining nylon salts.

The amount of water used in the aqueous solution method is not particularly limited, but is preferably 5000 parts by mass or less, more preferably 900 parts by mass or less, relative to 100 parts by mass of the total of the dicarboxylic acid and the diamine, from the viewpoint of productivity.

The reaction temperature in the aqueous solution method is preferably 80 to 100 ℃ and more preferably 90 to 100 ℃ or lower, from the viewpoint of solubility of the salt. The reaction time in the aqueous solution method may be a time until a uniform aqueous solution can be formed, and is preferably 0.1 to 3 hours, more preferably 0.1 to 2 hours, from the time when the reaction temperature is reached.

In the aqueous solution method, the aqueous solution is cooled after the reaction to precipitate the nylon salt in the aqueous solution, so that the nylon salt can be obtained.

The liquid method is a method of preparing a mixed solution by mixing a dicarboxylic acid and a diamine, and producing a nylon salt from the mixed solution.

In the liquid method, first, a dicarboxylic acid and a diamine are mixed at a temperature equal to or higher than the melting point of the diamine to obtain a mixed solution. At this time, when the mixing temperature is not lower than the melting point of the diamine, the dicarboxylic acid is dispersed in the mixed solution with the diamine as a solvent, or the dicarboxylic acid and the diamine are mixed in a liquid state.

The mixing time in the liquid method is preferably 0.1 to 2 hours, more preferably 0.1 to 1.0 hour, from the time when the reaction temperature is reached.

Then, the obtained mixed solution is stirred at a temperature lower than the melting point of the produced polyamide resin to react the dicarboxylic acid and the diamine, thereby obtaining a nylon salt.

The reaction temperature in the liquid method is preferably low to suppress the continuation of the polymerization of the formed salt, and is preferably lower than the melting point of the formed polyamide resin, more preferably 270 ℃ or lower.

In addition, from the viewpoint of sufficiently performing the salt formation, the reaction time in the liquid method is preferably 0.1 to 10 hours, more preferably 0.1 to 5 hours, from the time when the reaction temperature is reached. Such a reaction may be carried out under normal pressure or under pressure.

In the aqueous solution method and the liquid method, the nylon salt may be polymerized in a state of containing water or may be polymerized in a state of dried powder. Examples of the method for drying and powdering the water-containing nylon salt include a method of drying with a vacuum dryer, a spray drying method, and the like.

In the aqueous solution method or the liquid method, the nylon salt produced can be pulverized to obtain a nylon salt in a powder state. The nylon salt in powder form may contain an oligomer obtained by polymerizing a part of the nylon salt.

The solid method is a method in which diamine is added to a heated dicarboxylic acid powder at a certain ratio, and a nylon salt is produced by reacting the dicarboxylic acid with the diamine while maintaining the powder state of the dicarboxylic acid.

From the viewpoint of maintaining the powder state, the heating temperature of the dicarboxylic acid in the solid method is preferably a temperature equal to or higher than the melting point of the diamine and equal to or lower than the melting point of the dicarboxylic acid. The reaction time in the solid-state method is preferably 0 to 6 hours, more preferably 0.25 to 3 hours, from the end of the addition of the diamine, from the viewpoint of maintaining the powder state of the dicarboxylic acid.

The method of adding the diamine in the solid method is not particularly limited as long as the dicarboxylic acid is in a powder state. From the viewpoint of suppressing lumping of the obtained nylon salt, maintaining the powder state, and efficiently performing the production reaction, it is preferable to use a method of continuously adding diamine using a supply apparatus or the like, or a method of intermittently adding an appropriate amount of diamine per time (for example, 1/10 to 1/100 of the total amount of diamine added per time) (a method of repeatedly adding the diamine over a certain period of time), even in the addition method. Further, a combination of the above methods may be used. The supply device is not particularly limited, and a known supply device may be used.

In the method for producing a polyamide resin of the present invention, it is necessary to heat the nylon salt under normal pressure in the presence of water vapor in the reaction system. Since the boiling point of the diamine contained in the nylon salt is higher than 100 ℃, if the system is heated, water is preferentially gas compared with the diamine, and the diamine is not distilled out of the system. Further, when water vapor is present in the system, the volatilized diamine and water vapor are refluxed together, and thus are not distilled out of the system. As a result, the molar balance between the dicarboxylic acid and the diamine contained in the nylon salt is not unbalanced, and the nylon salt can be easily increased in molecular weight under normal pressure. The term "normal pressure" means a pressure at which the pressure in the reaction vessel is substantially the same as the atmospheric pressure in the environment in which the reaction vessel is installed, and specifically means that [ (atmospheric pressure) - (pressure in the reaction vessel) ] is about ± 0.01 MPa.

Examples of the method for allowing water vapor to be present in the reaction system include a method in which water or the like is added to the reaction vessel in advance before heating, a method in which water vapor is allowed to flow directly through the system before starting heating, and the like. These may be used in combination. By using these methods, since water vapor can be caused to exist in the system immediately after the start of heating, when the nylon salt is heated, the diamine free from the nylon salt can be inhibited from distilling out of the system, and a high-molecular-weight polyamide resin can be produced. Whether or not the diamine is distilled out of the system can be confirmed by comparing the molar ratio of the dicarboxylic acid and the diamine in the obtained polyamide resin. In the present invention, if the above molar ratio in the polyamide resin is 50/50 to 55/45, the molar balance is maintained.

When water is added to the reaction vessel before heating, the amount of water added is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the nylon salt. When the amount of water to be added is in the range of 0.5 to 10 parts by mass, the volatilization of diamine can be efficiently suppressed and the by-production of triamine can be suppressed. When the amount of water added is less than 0.5 part by mass, the amount of water vapor in the system immediately after heating is small, and the diamine may be distilled out of the system. On the other hand, if the amount of water added is more than 10 parts by mass, part of the nylon salt dissolves in water, and triamine is likely to be by-produced during polymerization.

When the steam is circulated in the system directly before the start of heating, the flow rate of the steam varies depending on the internal volume of the reaction vessel, and for example, when the internal volume is about 30L, it is preferably 0.2 to 1.0 g/min, more preferably 0.3 to 0.8 g/min.

In the production method of the present invention, water is produced as the polymerization proceeds, and the amount of water produced increases and decreases as the polymerization reaction proceeds. In the present invention, the molar fraction of water vapor in the atmosphere in the reaction vessel in the first half of the polymerization, in which the diamine is likely to volatilize, is preferably 10% or more, and more preferably 20 to 90%. Here, the first half of the polymerization is a period in which the rate of the terminal reaction is approximately 85% or less. As described later, the mole fraction of water vapor is calculated from the molar amount of water distilled off per unit time and the molar amount of the inert gas. When the molar fraction of water vapor is 10% or more, the diamine is converted into a gas in the system and refluxed together with water, so that the diamine is not distilled out of the system, and only water can be distilled out of the system. On the other hand, when the inert gas is not introduced, the steam is 100%, and when the amount of water distilled off decreases as the polymerization proceeds, there is a possibility that external air is mixed in.

In order to control the mole fraction of water vapor in the reaction vessel within the above range, it is preferable to distill a part of water produced by the polymerization reaction out of the system while refluxing the water. In the case where the reflux is not caused, even if water is added to the reaction vessel before heating, the steam in the reaction vessel is completely distilled off due to the size of the reaction vessel and the flow rate of the inert gas, and in the case where the steam is not substantially present in the reaction vessel at the start of the polymerization, the distillation of the diamine cannot be suppressed. In order to distill a part of water out of the system while refluxing the water, for example, a reflux apparatus such as a reflux tube or a reflux column may be provided in the reaction vessel. The length, cross section, temperature, and the like of the reflow apparatus at this time can be appropriately selected.

The length of the reflow apparatus, the cross-sectional shape of the reflow apparatus, the temperature of the reflow apparatus, and the like in the present invention are not particularly limited, and any of them may be appropriately selected.

The polymerization temperature is preferably 180 to 320 ℃, and more preferably 200 to 270 ℃. By setting the polymerization temperature to 180 to 320 ℃, the polymerization reaction can be efficiently carried out while suppressing the side reaction of the by-product such as triamine and the deterioration of the polymer. That is, if the polymerization temperature is less than 180 ℃, the polymerization rate may become too slow. On the other hand, if the temperature is higher than 320 ℃, the influence of side reaction may be observed, the triamine content may be increased, and the polyamide resin may be gelled.

The polymerization time is preferably 0.5 to 72 hours, more preferably 1 to 36 hours. If the time is less than 0.5 hour, the polymerization reaction may be insufficient. On the other hand, if it exceeds 72 hours, the amount of triamine as a by-product may increase as described above, and the polyamide resin may become a gel or the like.

In the production method of the present invention, as described above, it is preferable that water is distilled out of the system from the start to the end of the polymerization. This suppresses the hydrolysis reaction of the polyamide resin to be produced, and promotes the production of the polyamide resin. As a result, the polymerization time is shortened, the amount of triamine as a by-product in the obtained polyamide resin is suppressed, and the formation of gel or the like can be suppressed. More specifically, the polyamide resin obtained by the production method of the present invention can be produced in such a small amount that the amount of triamine in the polyamide resin is 0.3 mol% or less relative to the amount of diamine.

In the production method of the present invention, in order to prevent oxygen outside the system from being mixed into the reaction vessel and the contents from being deteriorated, it is preferable to flow an inert gas into the reaction vessel. However, if the flow rate of the inert gas is too large, the water may not flow back, and therefore it is preferable to appropriately adjust the flow rate of the inert gas in accordance with the progress of the reaction.

From the viewpoint of maintaining the steam atmosphere, the flow rate of the inert gas with respect to the volume of the reaction vessel is preferably 0.01 to 1L/min. Further, if the terminal reaction rate is 85 to 99%, the amount of water produced by the polymerization reaction is small. In this case, the ratio of the flow rate of the inert gas to the volume of the reaction vessel can be converted to 0.01 to 10L/min. The inert gas flow rate was a value at 25 ℃ and normal pressure.

In the method for producing a polyamide resin of the present invention, any of a melt polymerization method and a solid-phase polymerization method can be used for polymerizing the nylon salt. In the case of the solid-phase polymerization method, the nylon salt is preferably made into a granular or powdery form from the viewpoint of accelerating the progress of polymerization.

In the production method of the present invention, a catalyst is preferably used from the viewpoint of increasing the polymerization rate. Examples of the catalyst include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts thereof. These may be used alone, or 2 or more of them may be used in combination. The amount of the catalyst to be used may be such that it is used for general nylon polymerization, and is preferably 2 mol% or less based on the total mole number of the dicarboxylic acid and the diamine.

In the production method of the present invention, an end capping agent may be used for the purpose of adjusting the degree of polymerization, suppressing decomposition or coloration, or the like. Examples of the blocking agent include monocarboxylic acids and monoamines. Examples of the monocarboxylic acid include acetic acid, lauric acid, benzoic acid, and the like, and examples of the monoamine include octylamine, cyclohexylamine, aniline, and the like. These may be used alone, or 2 or more of them may be used in combination. The amount of the end-capping agent to be added may be the same as that used for polymerization of general nylon, and is preferably 5 mol% or less based on the total mole number of the dicarboxylic acid and the diamine.

The relative viscosity of the polyamide resin produced by the production method of the present invention is appropriately set according to the purpose, and if a polyamide which is easily molded is to be obtained, it is preferably 1.8 or more, and more preferably 2.0 or more.

The polyamide resin obtained by the production method of the present invention may contain an antioxidant, an antistatic agent, a flame retardant aid, a heat stabilizer, a fibrous reinforcing material, a filler, a pigment, and the like. Examples of the fibrous reinforcing material include glass fibers and carbon fibers. Examples of the filler include talc, expandable clay minerals, silica, alumina, glass beads, graphite, and fillers. Examples of the pigment include titanium oxide and carbon black.

The polyamide resin in the production method of the present invention may be copolymerized with a lactam such as caprolactam, if necessary. When the lactam is copolymerized, the copolymerization ratio is preferably 30 mol% or less, more preferably 20 mol% or less, based on the total amount of the dicarboxylic acid and the diamine. In addition, when the lactam compound is copolymerized, a method such as adding lactam to a nylon salt and then polymerizing the resulting mixture is used.

The polyamide resin obtained by the production method of the present invention can be processed into various molded articles, films, sheets, fibers, and the like by a known molding method such as injection molding, extrusion molding, blow molding, or the like, or by a known film-forming method or spinning method.

These molded articles, films, fibers and the like can be preferably used for various applications such as industrial materials and industrial materials for electric and electronic parts, automobile parts, office equipment parts and the like, household goods and the like.

Examples

The present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

The raw materials used in the examples and comparative examples are as follows:

(1) dicarboxylic acids

Terephthalic acid (volume average particle diameter: 80 μm powder)

Isophthalic acid (powder having a volume average particle diameter of 100 μm)

(2) Diamines

1, 9-Diaminononane (boiling point: 258 ℃ C.)

1, 10-diaminodecane (boiling point: 271 ℃ C.)

1, 12-diaminododecane (boiling point: 304 ℃ C.)

(3) AH salt

Nylon salts formed from equimolar adipic acid/1, 6-diaminohexane

(4) Other additives

Sodium hypophosphite monohydrate

Benzoic acid

The evaluation methods used in examples and comparative examples are as follows:

(1) mole fraction of water vapor in the reaction vessel

From the molar amount of water distilled off per unit time and the amount of inert gas, the following equation was used:

the mole fraction of water vapor in the reaction vessel was 100 × A/(A + B)

A: amount of water distilled off per unit time (mol)

B: amount of inert gas (mole) introduced per unit time

The amount of water distilled off was determined from the mass of water obtained by recondensing the water vapor discharged from the reaction vessel with a condenser. The amount of the inert gas is determined from the flow rate of the inert gas.

(2) Relative viscosity

A polyamide resin was dissolved in sulfuric acid (concentration: 96% by mass) as a solvent to prepare a sample solution having a concentration of 1 g/dL. Next, the fall times of the sample solution and the solvent were measured at a temperature of 25 ℃ using an Ubbelohde viscometer. Then, the relative viscosity was determined by the following equation.

Relative viscosity (falling time of sample solution)/(falling time of solvent only)

(3) Melting Point

10mg of a polyamide resin was heated from room temperature at 20 ℃ per minute to 350 ℃ and held for 5 minutes by a differential scanning calorimeter ("DSC-7" manufactured by Perkin Elmer). Then, the temperature was decreased to 25 ℃ at 500 ℃/min, and after keeping at 25 ℃ for 5 minutes, the temperature was increased to 400 ℃ at 20 ℃/min. The melting point temperature was defined as the peak of the peak from melting in the curve obtained at the second temperature rise.

(4) Triamine content of polyamide resin

3mL of hydrobromic acid (concentration: 47% by mass) was added to 10mg of a polyamide resin, and the mixture was heated at 130 ℃ for 16 hours and then cooled to room temperature. 5mL of an aqueous sodium hydroxide solution (concentration: 20% by mass) was added thereto to make the sample solution basic. Then, the sample solution was transferred to a separatory funnel, and 8mL of chloroform was added and stirred, followed by standing, and the chloroform phase was taken and concentrated. 1.5mL of chloroform was added thereto, and the resulting mixture was filtered through a membrane filter to obtain a measurement sample. The measurement sample was analyzed by a gas chromatograph equipped with a mass spectrometer (trade name "Agilent 6890N" manufactured by Agilent technologies). That is, the diamine and the triamine in the polyamide resin were quantified using a calibration curve prepared using the diamine and the triamine as standard samples, and the molar ratio of the triamine to the diamine was calculated. As a standard substance of diamine, diamine for polymerization was used. As a standard substance of triamine, a triamine compound obtained by heating and stirring diamine used for polymerization at 240 ℃ for 3 hours in an autoclave with palladium oxide as a catalyst and reacting the diamine compound was used.

(5) Volume average particle diameter of powder

The particle size distribution was measured by a laser diffraction/scattering particle size distribution measuring apparatus ("LA 920", horiba, Ltd.).

(6) Molar ratio of dicarboxylic acid to diamine, and terminal reaction rate

The polyamide resin was subjected to high-resolution nuclear magnetic resonance (ECA 500NMR, manufactured by Nippon electronic Co., Ltd.)¹H-NMR analysis was carried out to determine the molar ratio of the dicarboxylic acid to the diamine and the proportion of the terminals which reacted at all the terminals to form an amide bond. The analysis conditions are as follows:

resolution ratio: 500MH_Z

Solvent: deuterated trifluoroacetic acid

Temperature: 25 deg.C

Example 1

[ polymerization ]

10.0kg of AH salt and 200g of water were supplied to a reaction vessel having an internal volume of 30L and equipped with a double spiral blade, and melt-polymerized at 275 ℃ for 2 hours. The polymerization was carried out by passing nitrogen gas at 4L/min under normal pressure and distilling water out of the system while refluxing the water into the system. In addition, the reaction vessel is provided with a condenser with an inner diameter of 8cm and a height of 35cm, and the temperature in the condenser is controlled to be 80-85 ℃. The molar concentration of water vapor in the reaction vessel is maintained at 60-90% during the reaction.

After the polymerization was carried out, the terminal reaction rate was confirmed to be 95%, the nitrogen flow rate was changed to 20L/min, and the polymerization was further carried out for 1 hour to obtain a polyamide resin (polyamide 66). The polyamide resin was extruded from the reaction vessel under nitrogen pressure and pelletized with a strand cutter.

Further, the obtained polyamide 66 had a molar ratio of adipic acid to 1, 6-diaminohexane of 50/50.

Example 2

[ preparation of Nylon salt (aqueous solution method) ]

1473g of terephthalic acid, 1527g of 1, 10-diaminodecane (terephthalic acid: 1, 10-diaminodecane: 50 (molar ratio)) and 100kg of water were reacted at 97 ℃ for 1 hour under normal pressure. Then, the mixture was cooled to 25 ℃ to precipitate the nylon salt, and the salt was vacuum-dried at 120 ℃ for 12 hours to obtain a nylon salt powder.

[ polymerization ]

2850g of the nylon salt obtained above, 0.89g of sodium hypophosphite monohydrate, 10.28g of benzoic acid and 100g of water were supplied to a reaction vessel having an internal volume of 8L and equipped with a double screw blade, and solid-phase polymerized at 240 ℃ for 5 hours. The polymerization was carried out under normal pressure by distilling water out of the system while refluxing while passing nitrogen gas at 2L/min. In addition, the reaction vessel is provided with a condenser with an inner diameter of 4cm and a height of 10cm, and the temperature in the condenser is controlled to be 80-85 ℃.

After the polymerization, it was confirmed that the terminal reaction rate was 99% and the nitrogen flow rate was not changed, and the polymerization was further carried out for 2 hours to obtain a powdery polyamide resin (polyamide 10T).

Further, the polyamide 10T was obtained in which the molar ratio of terephthalic acid to 1, 10-diaminodecane was 50/50.

Example 3

[ preparation of Nylon salt (solid method) ]

A reaction vessel having an internal volume of 8L and equipped with a double-screw stirring blade was charged with 982g of terephthalic acid, and the mixture was heated to 165 ℃ while stirring at 60rpm under a nitrogen-sealed atmosphere. Then, 28.3g of 1, 10-diaminodecane (2.8 mass% of the total diamine) was added in portions to the terephthalic acid powder in 36 times per 5 minutes while maintaining 165 ℃. Further stirring was continued at 165 ℃ for 1 hour to obtain a nylon salt in the form of powder.

[ polymerization ]

The reaction vessel containing the powdered nylon salt was cooled to 40 ℃ and 40g of water was added. Then, the nylon salt was solid-phase polymerized at 240 ℃ for 5 hours with heating. The polymerization was carried out under normal pressure by distilling water out of the system while refluxing while passing nitrogen gas at 2L/min. In addition, the reaction vessel is provided with a reflux device with an inner diameter of 4cm and a height of 10cm, and the temperature in the condenser is controlled to be 80-85 ℃. After the polymerization, the terminal reaction rate was confirmed to be 99%, and the polymerization was further carried out for 2 hours to obtain a powdery polyamide resin (polyamide 10T).

Examples 4 to 8

A powdery polyamide resin (polyamide 10T) was obtained by polymerization after adjusting a nylon salt in the same manner as in example 3, except that the amount of water added in the polymerization step was changed as shown in table 1.

Example 9

[ preparation of Nylon salt (solid method) ]

A nylon salt was prepared in the same manner as in the preparation of the nylon salt in example 3.

[ polymerization ]

The temperature in the reaction vessel containing the nylon salt was increased to 240 ℃ over 1 hour while blowing nitrogen gas at a flow rate of 2L/min and saturated steam at a flow rate of 0.7MPa at a flow rate of 0.5 g/min. After reaching 240 ℃, the solid phase polymerization was carried out at 240 ℃ for 3 hours while maintaining the flow rates of nitrogen and water vapor.

Then, the supply of water vapor was stopped, and solid-phase polymerization was further carried out for 2 hours. The polymerization was carried out under normal pressure by distilling water out of the system under reflux. In addition, the reaction vessel is provided with a reflux device with an inner diameter of 4cm and a height of 10cm, and the temperature in the condenser is controlled to be 80-85 ℃. After the polymerization, the terminal reaction rate was confirmed to be 99%, and the polymerization was further carried out for 2 hours to obtain a powdery polyamide resin (polyamide 10T).

Example 10

[ preparation of Nylon salt (aqueous solution method) ]

1031g of terephthalic acid, 442g of isophthalic acid, 1527g of 1, 10-diaminodecane (terephthalic acid: isophthalic acid: 1, 10-diaminodecane: 35: 15: 50 (molar ratio)) and 100kg of water were reacted at 97 ℃ for 1 hour under normal pressure. Then, the mixture was cooled to 25 ℃ to precipitate the nylon salt, and the salt was vacuum-dried at 120 ℃ for 12 hours to obtain a nylon salt powder.

[ polymerization ]

The same operation as in the polymerization in example 2 was carried out to obtain a powder of a polyamide resin (polyamide 10 TI).

Example 11

[ preparation of Nylon salt (solid method) ]

1024g of terephthalic acid was supplied to a reaction vessel having an internal volume of 8L and equipped with a double-helix stirring blade, and the mixture was heated to 160 ℃ while stirring at a rotation speed of 60rpm under a nitrogen-sealed atmosphere. Then, 27.1g of nonanediamine (2.8 mass% of the total amount of diamine) was added in 36 portions to the terephthalic acid powder every 5 minutes while maintaining 160 ℃. Further stirring was continued at 160 ℃ for 1 hour to obtain nylon powder.

[ polymerization ]

The temperature in the reaction vessel containing the nylon salt was cooled to 40 ℃ and 40g of water was added. Then, the mixture was heated and solid-phase polymerized at 240 ℃ for 5 hours. The polymerization was carried out under normal pressure by distilling water out of the system while refluxing while passing nitrogen gas at 2L/min. In addition, the reaction vessel is provided with a reflux device with an inner diameter of 4cm and a height of 10cm, and the temperature in the condenser is controlled to be 80-85 ℃. After the polymerization, the terminal reaction rate was confirmed to be 99%, and the polymerization was further carried out for 2 hours to obtain a powdery polyamide resin (polyamide 9T).

Example 12

[ preparation of Nylon salt (solid method) ]

907g of terephthalic acid was supplied to a reaction vessel having an internal volume of 8L and equipped with a double-helix stirring blade, and the vessel was heated to 160 ℃ while stirring at a rotation speed of 60rpm under a nitrogen-sealed atmosphere. Then, 1093g was added in 36 portions to the terephthalic acid powder at 30.4g (2.8 mass% of the total diamine) per 5 minutes while maintaining 160 ℃ (terephthalic acid: dodecanediamine: 50 (molar ratio)). Further stirring was continued at 160 ℃ for 1 hour to obtain a nylon salt in the form of powder.

[ polymerization ]

The reaction vessel containing the nylon salt was cooled to 40 ℃ and 40g of water was added. Then, the mixture was heated and solid-phase polymerized at 240 ℃ for 5 hours. The polymerization was carried out under normal pressure by distilling water out of the system while refluxing while passing nitrogen gas at 2L/min. In addition, the reaction vessel is provided with a reflux device with an inner diameter of 4cm and a height of 10cm, and the temperature in the condenser is controlled to be 80-85 ℃. After the polymerization, the terminal reaction rate was confirmed to be 99%, and the polymerization was further carried out for 2 hours to obtain a powdery polyamide resin (polyamide 12T).

Comparative example 1

[ polymerization ]

10.0kg of AH salt and 5.0kg of water were supplied to an autoclave having an internal volume of 30L and provided with a double spiral blade. Subsequently, the inside of the autoclave was replaced with nitrogen, and then melt-polymerized at 275 ℃ for 3 hours under a closed condition with the internal pressure controlled at 1.5MPa (i.e., under pressure).

The inside of the autoclave was returned to normal pressure, and after confirming that the terminal reaction rate was 90%, polymerization was further carried out under a nitrogen flow of 20L/min for 1 hour to obtain a polyamide resin (polyamide 66). The obtained polyamide resin was extruded from an autoclave by nitrogen pressure and pelletized by a strand cutter.

Comparative example 2

[ polymerization ]

10.0kg of a nylon salt comprising adipic acid/1, 6-diaminohexane and 200g of water were supplied to a reaction vessel having a capacity of 30L and equipped with a double screw blade, and melt-polymerized at 275 ℃ for 2 hours. The polymerization was carried out under normal pressure while flowing nitrogen gas at 40L/min without refluxing. After the polymerization, the terminal reaction rate was confirmed to be 95%, and the polymerization was further carried out for 1 hour to obtain a polyamide resin (polyamide 66). The obtained polyamide resin was extruded from the reaction vessel with nitrogen pressure.

Comparative example 3

The same operation as in example 3 was carried out except that no water was added in the step of [ polymerization ], to obtain a polyamide resin.

Table 1 shows the production conditions and the characteristic values of the polyamide resins obtained in examples 1 to 12. Table 2 shows the production conditions and the characteristic values of the obtained polyamide resins in comparative examples 1 and 2.

[ Table 1]

[ Table 2]

In tables 1 and 2, the amount of water added is represented by the ratio of water to 100 parts by mass of the nylon salt, and is simply shown below.

HA: 1, 6-diaminohexane

NA: 1, 9-diaminononanes

DA: 1, 10-diaminodecane

DDA: 1, 12-diaminododecane

AA: adipic acid

TPA: terephthalic acid (TPA)

IPA: isophthalic acid

In each of examples 1 to 12, a part of water was distilled out of the system and polymerized while refluxing under normal pressure, and thus the polyamide resin could be efficiently increased in molecular weight. Therefore, the polymerization time was shorter and the amount of triamine was smaller than that in comparative example 1 in which polymerization was carried out under pressure.

In examples 1 and 2, since the molar ratio of the dicarboxylic acid to the diamine in the raw material such as nylon salt and the obtained polyamide resin was 50/50, it was judged that the diamine was not substantially distilled out of the system.

In examples 2, 3 and 8, in the polymerization of terephthalic acid and 1, 10-diaminodecane, 0.5 to 10 parts by mass of water per 100 parts by mass of the nylon salt was previously added to the reaction vessel for polymerization before the polymerization. Therefore, the reaction vessel is sufficiently filled with water vapor from the start of polymerization. As a result, the relative viscosity of the obtained polyamide resin was higher than that of examples 4 and 5 in which the amount of water added was less than the amount defined in the present invention. In addition, the amount of triamine was smaller than that in example 6 in which the amount of water added was larger than the amount defined in the present invention.

In example 9, polymerization was carried out by passing water vapor directly through the system before starting heating. Therefore, the reaction vessel is sufficiently filled with water vapor from the start of polymerization. As a result, the obtained polyamide resin had a high relative viscosity and a small amount of triamine.

In comparative example 1, the polyamide resin was polymerized under pressure. Therefore, the polymerization time was longer than that in example 1, and the obtained polyamide resin was a resin containing a large amount of triamine.

In comparative example 2, since water was not refluxed into the polymerization reaction system, all of the water vapor was distilled off, and at the start of the polymerization, substantially no water vapor was present in the system, and a part of the diamine was distilled off to the outside of the system. As a result, the obtained polyamide resin had a low relative viscosity without increasing the molecular weight.

In comparative example 3, since polymerization was carried out without adding water and without refluxing water into the polymerization reaction system, the amount of water vapor in the system at the start of polymerization was small and a part of the diamine distilled out of the system. As a result, the obtained polyamide resin had a low relative viscosity without increasing the molecular weight.

Since the method for producing a polyamide resin of the present invention is a method in which polymerization is performed under normal pressure, the polymerization time is shortened as compared with the case of performing polymerization under pressure, and a high-molecular-weight polyamide resin with a small amount of triamine which causes gelation can be obtained. Further, since a pressurizing device is not required, the cost for introducing and maintaining the device is low, and thus it is useful.

Claims (3)

1. A method for producing a polyamide resin, characterized in that at the start of heating, 0.5 to 10 parts by mass of water is preliminarily present in a system per 100 parts by mass of a nylon salt, and a nylon salt obtained from a dicarboxylic acid and a diamine having a boiling point of more than 100 ℃ is heated under normal pressure in the presence of water vapor in the system, wherein the polyamide resin is composed of a dicarboxylic acid component and a diamine component, and wherein water is distilled out of the system while refluxing the water into the system without distilling the diamine out of the system during the heating.

2. A process for producing a polyamide resin, which comprises flowing water vapor through a system at the start of heating, heating a nylon salt comprising a dicarboxylic acid and a diamine component at normal pressure, wherein the nylon salt comprises a dicarboxylic acid and a diamine and has a boiling point of greater than 100 ℃ in the presence of water vapor in a molar fraction of 10% or more in the system, and wherein water is distilled out of the system while refluxing the water into the system without distilling the diamine out of the system during the heating.

3. The method for producing a polyamide resin as claimed in any one of claims 1 and 2, wherein at least one selected from the group consisting of 1, 10-diaminodecane, 1, 11-diaminoundecane, and 1, 12-diaminododecane is used as the diamine.