JP3551991B2 - Production method of copolyamide - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for producing a copolymerized polyamide by directly polycondensing a mixed diamine and a mixed dicarboxylic acid under normal pressure. More specifically, the present invention provides an economical method for producing a copolyamide in which a mixed diamine composed of meta-xylylenediamine and paraxylylenediamine is copolymerized with a mixed dicarboxylic acid composed of adipic acid and terephthalic acid.
The copolymerized polyamide obtained by the above reaction has high heat resistance and is crystalline.
[0002]
[Prior art]
When the dicarboxylic acid and the diamine are directly mixed and the polycondensation reaction is carried out under normal pressure, the reaction initiation temperature is raised to the melting point of the dicarboxylic acid or higher, and the reaction system containing the raw material mixture is raised so as to be able to maintain a substantially uniform molten state. The reaction proceeds while being heated, and before the reaction rate reaches 95%, the temperature of the reaction system is raised to a temperature of 30 ° C. lower than the melting point of the polyamide that generates the reaction system. A method for producing a polyamide characterized by controlling the reaction temperature so that the reaction can be carried out by the method described in JP-B-1-14925 is disclosed. According to this production method, a method is employed in which the diamine is continuously added to the reaction system while maintaining the resulting reaction system containing the oligoamide / polyamide in a uniform molten state.
[0003]
In the above production method, the polycondensation reaction device does not need to be a pressure-resistant vessel, and can be installed at extremely low cost. In addition, this method does not require any time required for operations such as pressurization and depressurization, and the time required for distilling off water, which is a necessary solvent in the case of a known aqueous solution method. In addition, the amount of heat required for concentrating the aqueous solution in the conventional pressurization method is not required at all, and the amount that can be charged in one reaction can be increased, thereby increasing the productivity. Thus, a very economical method for producing polyamide is provided.
However, the heat in this normal pressure direct polycondensation comprising since it is difficult to maintain a uniform state of the reaction system from the difference in reactivity of the aliphatic dicarboxylic acid and an aromatic dicaprate Le Bon acid, an aromatic dicarboxylic acid However, it has not been possible to produce a functional polyamide, particularly a copolymer polyamide having excellent rigidity retention at high temperatures.
[0004]
[Problems to be solved by the invention]
Various polyamides using an aromatic dicarboxylic acid in the dicarboxylic acid component have been developed so far, and the market is expanding as a useful material mainly used for metal replacement. These polyamides are generally produced by a pressurized aqueous solution method from a nylon salt, and as described above, have many problems in terms of economy and quality of the produced polyamide. In addition, the existing atmospheric pressure direct polycondensation method synthesizes a copolyamide obtained from a diamine composed mainly of paraxylylenediamine and metaxylylenediamine, and a dicarboxylic acid composed mainly of adipic acid and terephthalic acid. In this case, it is difficult to keep the reaction system containing the produced polyamide in a uniform molten state.
[0005]
[Means for Solving the Problems]
The present inventors have assiduously studied, and found a method for suitably producing a copolymerized polyamide by controlling the degree of reaction in a stepwise manner during the direct polycondensation of a mixed dicarboxylic acid and a mixed diamine. It was completed.
[0006]
That is, the present invention relates to a mixed diamine having a metaxylylenediamine content of 35 to 70 mol% and a paraxylylenediamine content of 30 to 65 mol% , and an adipic acid content of 40 to 80 mol% . A method for producing a copolymerized polyamide, comprising subjecting a mixed dicarboxylic acid having a terephthalic acid content of 20 to 60 mol% to a polycondensation reaction,
1) heating the mixed dicarboxylic acid to a temperature lower than the melting point of adipic acid and lower by 30 ° C. than the melting point of the resulting copolymerized polyamide,
2) Start the dropping of the mixed diamine in the heated mixed dicarboxylic acid and continue dropping continuously,
3) Before the reaction rate of the mixed dicarboxylic acid reaches the [adipic acid content (of the mixed dicarboxylic acid ) (mol%)-5] mol%, the temperature of the reaction system is finally adjusted to the melting point of the copolymerized polyamide. Rises to a temperature higher than 30 ° C lower than
4) Diamine is added dropwise until the molar ratio of diamine to dicarboxylic acid is 0.97 to 1.03,
5) The present invention relates to a method for producing a copolymerized polyamide, characterized in that the temperature of the reaction system at the end of the dropping of the diamine is controlled to a temperature not lower than the melting point of the finally produced copolymerized polyamide.
[0007]
In the present invention, the following mixed diamine and mixed dicarboxylic acid are used.
(1) Mixed diamine A mixed diamine containing 35 to 70 mol% of meta-xylylenediamine and 30 to 65 mol% of para-xylylenediamine is used. Here, the concentrations of meta-xylylenediamine and para-xylylenediamine of the mixed diamine may be within the above-mentioned concentration ranges, respectively.
If the paraxylylenediamine content in the mixed diamine is less than 30 mol%, the crystallinity of the obtained copolymerized polyamide will be reduced. If the content of paraxylylenediamine in the mixed diamine exceeds 65 mol%, the melting point of the obtained copolymerized polyamide may exceed 300 ° C., and the moldability is significantly reduced.
[0008]
In the present invention, the mixed xylylenediamine further contains, as other diamines, aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, and paraphenylenediamine. And alicyclic diamines such as 1,3-bisaminomethylcyclohexane and 1,4-bisaminomethylcyclohexane can be used in an amount of 20 mol% or less in the total diamine.
[0009]
(2) Mixed dicarboxylic acid As the mixed dicarboxylic acid, a mixed dicarboxylic acid containing 40 to 80 mol% of adipic acid and 20 to 60 mol% of terephthalic acid is used.
If the content of adipic acid in the mixed dicarboxylic acid is less than 40 mol%, it is difficult to ensure the fluidity of the mixed dicarboxylic acid before the start of diamine dropping, which is not preferable.
If the terephthalic acid content in the mixed dicarboxylic acid is less than 20 mol%, the heat resistance of the obtained copolymerized polyamide, particularly the rigidity retention at high temperatures, is undesirably reduced. If the terephthalic acid content in the mixed dicarboxylic acid exceeds 60 mol%, the resulting copolyamide contains three-dimensional compounds such as rubbery substances and solidified substances during the reaction, making it difficult to produce a uniform product. Is not preferred.
According to the production method of the present invention, it is possible to directly produce a copolymerized polyamide from a mixed diamine and a mixed dicarboxylic acid without using a solvent and without being particularly limited by the reaction pressure. However, it is desirable to perform the process under normal pressure or reduced pressure in manufacturing and operating the device.
[0011]
In carrying out the production method of the present invention, it is desirable to use the following apparatus and under the operating conditions.
(A) A reaction vessel equipped with a stirrer and a decompressor is used.
(B) In order to produce a uniform copolymerized polyamide without coloring, the inside of the reaction vessel is sufficiently replaced with an inert gas before the dicarboxylic acid is charged into the reaction vessel.
In the production of the copolymerized polyamide of the present invention, after the dicarboxylic acid is charged into the reaction vessel, the copolymerized polyamide is produced under the following conditions.
[0012]
(1) heating the mixed dicarboxylic acid to a temperature higher than the melting point of adipic acid and lower than the temperature lower by 30 ° C. than the melting point of the copolymerized polyamide to be produced;
{Circle around (2)} Starting the dropping of the mixed diamine into the heated mixed dicarboxylic acid and continuously dropping it,
(3) Before the reaction rate of the mixed dicarboxylic acid reaches [the content of adipic acid in the mixed dicarboxylic acid (mol%)-5] mol%, the temperature of the reaction system is determined from the melting point of the finally produced copolymerized polyamide. Also rises to a higher temperature than the 30 ° C lower temperature,
(4) The diamine is added dropwise until the molar ratio of the diamine to the dicarboxylic acid is 0.97 to 1.03,
(5) The temperature of the reaction system at the end of the dropping of the diamine is controlled to a temperature equal to or higher than the melting point of the finally produced copolymerized polyamide.
Hereinafter, each of the above steps will be described.
[0013]
Process ▲ 1 ▼
Heating the mixed dicarboxylic acid to a temperature higher than the melting point of adipic acid and lower than the melting point of the resulting copolymerized polyamide by 30 ° C.,
That is, in order to keep the reaction temperature above the melting point of adipic acid and to keep the reaction system in a fluid state, the reaction system is heated to a temperature higher than the melting point of adipic acid and lower than the melting point of the produced copolyamide by 30 ° C. or lower.
In this case, since the flow state of the reaction system can be maintained, the dicarboxylic acid does not necessarily need to be in a molten state, and may be in a slurry state.
[0014]
Process ▲ 2 ▼
The addition of the mixed diamine into the heated mixed dicarboxylic acid is started and continued to be continued.
That is, by dropping the mixed diamine, the mixed diamine and the mixed dicarboxylic acid are mixed and kept at a temperature equal to or higher than the melting point of adipic acid to start the polycondensation reaction, but the amidation reaction substantially occurs. It is desirable to raise the temperature to a temperature of 160 ° C. or higher, and to set a temperature at which the oligoamide and / or polyamide produced as an intermediate is in a molten state and the entire reaction system can maintain a uniform fluidized state. Is desirable. As a preferred polymerization operation, the dicarboxylic acid in a molten or slurry state is stirred in a reaction vessel, and the mixed diamine is added thereto under normal pressure, and the reaction mixture is maintained at a temperature equal to or higher than the melting point of the oligoamide and / or polyamide. This is done by:
[0015]
Here, the addition rate of the mixed diamine is determined in consideration of the heat of formation of the amidation reaction, the amount of heat consumed for distilling off the condensation product water, the structure of the condensing device and the cooler for separating the condensation product water and the raw material compound, and the like. The temperature is selected in consideration of a predetermined reaction temperature, that is, a temperature at which the reaction system containing the raw material compound can be maintained in a uniform fluidized state.
Usually, the time required for dropping the mixed diamine varies depending on the size of the reaction vessel, but is in the range of 0.5 hours to 10 hours. During this time, the condensed water generated with the progress of the reaction is distilled out of the reaction system through a condensing device and a cooler in which the temperature of the vapor at the top of the column is controlled at 100 to 120 ° C. Raw materials such as diamine and dicarboxylic acid that are scattered are collected by a decomposer and returned to the reaction vessel again.
[0016]
Process ▲ 3 ▼
Before the reaction rate of the mixed dicarboxylic acid reaches [adipic acid content in dicarboxylic acid (mol%)-5] (mol%), the temperature of the reaction system is 30 ° C. lower than the melting point of the finally formed polyamide. Raise the temperature above the temperature. That is, the oligoamide or polyamide generated in the polycondensation reaction, when the molecular weight increases with the progress of the reaction, the melting point of the reaction product increases, the viscosity of the reaction mixture increases, and the temperature rise of the contents is hindered. As a result, the reaction mixture is easily solidified. Therefore, the reaction temperature must be controlled so as to increase in accordance with the progress of the reaction, and the reaction system, that is, the reaction product must always be kept in a uniform fluid state.
[0017]
In the method of the present invention, this temperature control is performed by finally adjusting the temperature of the reaction system before the reaction rate of the reaction raw material reaches [adipic acid content in dicarboxylic acid (mol%)-5] (mol%). It is carried out so that the temperature is raised to a temperature lower by 30 ° C. than the melting point of the produced copolyamide. Here, the reaction rate is represented by the ratio of the functional groups that initially existed that caused a reaction. The reaction rate can be confirmed by the amount of water generated by the polycondensation reaction. When the reaction rate is [adipic acid content in dicarboxylic acid (mol%)-5] (mol%) or less, the added diamine reacts in a short time in the reaction system. The reaction rate can also be estimated from the dropping ratio of the diamine.
[0018]
The upper limit of the temperature of the reaction system to be controlled need not be particularly limited, but a temperature not exceeding 50 ° C. from the melting point of the finally formed polyamide is desirable in consideration of the heat history given to the product. When the reaction temperature is set to the above-mentioned predetermined temperature after the reaction rate exceeds [adipic acid content in dicarboxylic acid (mol%)-5] (mol%), the polyamide as a reaction product is reduced before the temperature rise. Partial crystallization begins to appear, making it very difficult to bring the reaction product into a uniform fluid state. The solidification phenomenon that occurs in the reaction product causes a thickening of the reaction system, a decrease in thermal conductivity, and sometimes even the danger of solidifying the entire reaction product. Under such conditions, the polyamide is produced on an industrial scale. It is virtually impossible.
[0019]
Process ▲ 4 ▼
The diamine is dropped until the molar ratio of the diamine to the dicarboxylic acid becomes 0.97 to 1.03, and at the end of the dropping of the diamine, the temperature of the reaction system is controlled to a temperature equal to or higher than the melting point of the finally produced polyamide. I do.
That is, the reaction system in which the reaction rate exceeds [adipic acid content in dicarboxylic acid (mol%)-5] (mol%) and is heated to a temperature not lower than the temperature specified in the present invention, until the reaction is completed. During this time, the temperature is gradually increased so that the reaction product containing the polyamide can maintain a uniform fluidized state.
[0020]
As described above, the reaction starts at a temperature of 160 ° C. or higher, which is higher than the melting point of adipic acid as a raw material dicarboxylic acid, and is 30 ° C. lower than the melting point of polyamide finally formed from the start of the reaction. It is also possible to raise the temperature of the reaction system to a temperature that is lower than or equal to ° C.
However, from a thermoeconomic point of view or from the viewpoint of the thermal history of the reaction product, it is not always preferable to keep the reaction system at a high temperature from the beginning of the reaction. After the acid content (mol%)-5] (mol%) is exceeded, the reaction system is preferably maintained at a temperature 30 ° C. lower than the melting point of the finally produced polyamide of the present invention.
[0021]
Process ▲ 5 ▼
The temperature of the reaction system at the end of the dropping of the diamine is controlled to a temperature equal to or higher than the melting point of the finally formed copolymerized polyamide.
That is, the reaction rate is higher than the content of adipic acid in the dicarboxylic acid (mol%)-5] (mol%) and the reaction system heated to a temperature not lower than the temperature specified in the present invention until the reaction is completed. The temperature is gradually increased so that the reaction product containing the copolymerized polyamide can maintain a substantially uniform fluid state.
[0022]
When the method of the present invention is carried out, it is inevitable to distill the diamine out of the reaction system, as in the case of the conventionally known aqueous solution pressurization method. It is. By providing the decomposer, the diamine can be effectively prevented from distilling out during the reaction. As a result, the charged molar ratio of diamine to dicarboxylic acid containing adipic acid can be reduced to 0.97 in consideration of the reached molecular weight. By setting the value in the range of 1.03 to 1.03, a polyamide having a constant molecular weight can be produced with good reproducibility.
[0023]
The polycondensation reaction device used in the method of the present invention does not need to be a pressure-resistant container, and can be installed at extremely low cost. In addition, the method of the present invention does not require the time required for operations such as pressurization and depressurization, and the time required for distilling off water, which is a solvent required in the case of a known aqueous solution method. In addition, the amount of heat required for the concentration of the aqueous solution in the conventional method is not required at all, and the amount that can be charged in one reaction can be increased, thereby increasing the productivity. Thus, a very economical method for producing polyamide is provided.
[0024]
【Example】
Hereinafter, the present invention will be described based on examples.
[0028]
Example 1
3.500 kg of accurately weighed adipic acid and 1.705 kg of terephthalic acid were placed in a 50 L reaction vessel equipped with a stirrer, a decomposer, a thermometer, a dropping funnel and a nitrogen gas inlet tube, and sufficiently purged with nitrogen. Adipic acid was dissolved at 170 ° C. in a small amount of nitrogen stream to make a uniform fluid state. To this, 2.969 kg of a mixed xylylenediamine (mole ratio: 7/3) of meta-xylylenediamine and para-xylylenediamine was added dropwise with stirring over 80 minutes. During this time, the internal temperature was continuously raised to 227 ° C.
[0029]
Subsequently, 0.966 kg of the mixed xylylenediamine was added dropwise with stirring over 26 minutes. During this time, the internal temperature was continuously raised to 245 ° C. Subsequently, 0.632 kg of mixed xylylenediamine was continuously added dropwise over 40 minutes with stirring. During this time, the reaction temperature was continuously raised from 245 ° C to 255 ° C. Water distilled off along with the dropwise addition of the mixed xylylenediamine was removed from the system through a condensing device and a condenser.
[0030]
After dropping the mixed xylylenediamine, the internal temperature was continuously raised to 260 ° C., and the reaction was continued for 34 minutes. Thereafter, the internal pressure of the reaction system was continuously reduced to 600 mmHg for 10 minutes, and then the reaction was continued for 44 minutes. During this time, the reaction temperature was continuously raised from 260 ° C to 270 ° C. During the entire reaction, no phenomenon was observed in which the generated oligomer or polyamide solidified and precipitated, and the reaction system lost a uniform fluid state.
The relative viscosity (96% sulfuric acid solution 1 g / 100 mL) of the obtained polyamide was 1.74, and the melting point was 246 ° C.
[0031]
Example 2
7.000 kg of adipic acid and 3.410 kg of terephthalic acid, which were precisely weighed, were placed in a 50-liter reactor equipped with a stirrer, a decomposer, a thermometer, a dropping funnel and a nitrogen gas inlet tube, and sufficiently purged with nitrogen. Further, adipic acid was dissolved at 170 ° C. in a small amount of nitrogen stream to make a uniform fluid state. To this, 5.967 kg of mixed xylylenediamine (molar ratio 6/4) of meta-xylylenediamine and para-xylylenediamine was added dropwise with stirring over 79 minutes. During this time, the internal temperature was continuously raised to 239 ° C.
[0032]
Subsequently, 1.928 kg of mixed xylylenediamine was added dropwise over 25 minutes while stirring. During this time, the internal temperature was continuously raised to 261 ° C. Subsequently, 1.285 kg of mixed xylylenediamine was continuously added dropwise with stirring for 60 minutes. During this time, the reaction temperature was continuously raised from 261 ° C to 267 ° C. Water distilled off along with the dropwise addition of the mixed xylylenediamine was removed from the system through a condensing device and a condenser. After the completion of the dropwise addition of the mixed xylylenediamine, the internal temperature was continuously raised to 271 ° C., and the reaction was continued for 40 minutes. Thereafter, the internal pressure of the reaction system was continuously reduced to 600 mmHg for 10 minutes, and then the reaction was continued for 43 minutes. During this time, the reaction temperature was continuously raised from 271 ° C to 275 ° C. In the whole process of the reaction, the generated oligomer or polyamide was not solidified and precipitated, and the phenomenon that the reaction system lost a uniform fluid state was not observed. The relative viscosity of the main component of the obtained polyamide (1 g of a 96% sulfuric acid solution / g) 100 mL) was 2.03 and the melting point was 257 ° C.
[0033]
Comparative Example 1
96.7 g of adipic acid and 256.1 g of terephthalic acid precisely weighed were placed in a 3 liter flask equipped with a stirrer, a separator, a thermometer, a dropping funnel and a nitrogen gas inlet tube, and sufficiently purged with nitrogen. Although dissolved adipic acid at 170 ° C. under a slight nitrogen stream, did not become a uniform flow state. To this, 75.0 g of mixed xylylenediamine (molar ratio: 7/3) of meta-xylylenediamine and para-xylylenediamine was added dropwise with stirring over 23 minutes. During this time, the internal temperature was continuously raised to 255 ° C.
[0034]
Subsequently, 165.0 g of mixed xylylenediamine was added dropwise over 50 minutes while stirring. During this time, the internal temperature was continuously raised to 264 ° C. Subsequently, 60.0 g of mixed xylylenediamine was continuously added dropwise with stirring for 19 minutes. During this time, the reaction temperature was continuously raised from 264 ° C to 270 ° C. Water distilled off along with the dropwise addition of the mixed xylylenediamine was removed from the system through a condensing device and a condenser. After the completion of the dropwise addition of the mixed xylylenediamine, the internal temperature was raised to 290 ° C., and the reaction was continued for 21 minutes. During this time, the viscosity of the resulting polyamide increased sharply, and the contents could not be stirred.
An attempt was made to dissolve the contents in 96% sulfuric acid, but the insoluble content was high.
[0037]
【The invention's effect】
When producing a copolymerized polyamide mainly using meta-xylylenediamine and para-xylylenediamine, and adipic acid and terephthalic acid, by adopting the production method of the present invention, it has excellent crystallinity and excellent heat resistance. In addition, it is possible to obtain a homogeneous copolymer polyamide having no coloring.

Claims (2)

A mixed diamine having a metaxylylenediamine content of 35 to 70 mol% and a paraxylylenediamine content of 30 to 65 mol% , an adipic acid content of 40 to 80 mol% , and a terephthalic acid content Is a method for producing a copolymerized polyamide by a polycondensation reaction with a mixed dicarboxylic acid having 20 to 60 mol%,
1) heating the mixed dicarboxylic acid to a temperature not lower than the melting point of adipic acid and lower than the melting point of the resulting copolymerized polyamide by 30 ° C.,
2) Start dropping the mixed diamine in the heated mixed dicarboxylic acid and continue dropping continuously,
3) mixing the reaction rate of the dicarboxylic acid [the adipic acid content (mol%) - 5] before reaching mol%, 30 ° C. below the melting point of the copolymerized polyamide to produce the temperature of the reaction system finally Rise to a higher temperature than
4) Diamine is added dropwise until the molar ratio of diamine to dicarboxylic acid is 0.97 to 1.03,
5) A method for producing a copolymerized polyamide, wherein the temperature of the reaction system at the end of the dropwise addition of the diamine is controlled to a temperature equal to or higher than the melting point of the finally produced copolymerized polyamide. The method for producing a copolymerized polyamide according to claim 1, wherein the mixed diamine and the mixed dicarboxylic acid are reacted under normal pressure or under pressure.