JPH0314831A - Preparation of polyamide - Google Patents

Abstract

PURPOSE:To prepare a high-quality high-mol.wt. polyamide easily and conveniently at a low cost by separating a heating medium and/or a washing solvent from the reaction product by filtration under heating through a specific porous body after the polymn. of the polyamide in the heating medium and/or after the washing of the reaction product. CONSTITUTION:An aliph. or arom. diamine is reacted with an aliph. or arom. dicarboxylic acid, aminocarboxylic acid, or lactam to produce an aligoamide or polyamide. In the process wherein the oligoamide or polyamide is reacted in an inert gas atmosphere at 100-300 deg.C for 10-50hr in a heating medium comprising a thermally stable org. compd. which is fluid at the reaction temp. and swells but does not dissolving the oligoamide or polyamide. The reaction product is washed with a washing solvent and the heating medium and/or the washing solvent are separated by filtration under heating through a porous body installed at the bottom of a reactor after the polymn. and/or the washing.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing a polyad, more specifically a method for producing a high molecular weight polyad by polymerizing while blowing an inert gas in a heat medium. It is related to. The present inventors have previously proposed ultra-high molecular weight polyamide by a new means of polymerization in a heating medium.
The present invention relates to a method for polymerization in a heating medium that is simpler, causes fewer operational troubles, and is advantageous in terms of cost. (Prior art) Polyamides, typified by nylon 6, are widely used in fibers, films, and plastics, and improving the mechanical properties such as strength and elastic modulus of these products is a challenge in each field. It is strongly desired. As a means to improve such mechanical properties, it is essential to devise a method for shaping the polymer and to increase the molecular weight of the polymer itself.

Many proposals have been made to increase the molecular weight of polyamides. As one of these, we proposed a method for producing high-molecular-weight boria ξ-d by polymerizing while blowing an inert gas into a heating medium (Japanese Patent Application Laid-Open No. 63-1989-1).
(See Publication No. 8416). (Problems to be Solved by the Invention) A method by which a high molecular weight polyamide can be obtained by the method described above;
On the other hand, there was a problem in that the heating medium used in polymerization remained in the polymer after polymerization. This residual heating medium causes discoloration, decomposition, etc. when forming, so it is necessary to promptly wash and remove it.

Conventionally, in order to remove the residual heating medium, it has been necessary to undergo a complicated process of filtering the polymer after polymerization, transferring it to a washing container, and washing it with a solvent.

(Means for Solving the Problems) In order to solve the above problems, the inventors of the present invention have conducted extensive research, and as a result, have finally completed the invention. That is, the present invention provides an aliphatic and/or aromatic diamine and an aliphatic and/or aromatic diamine.
Or, when producing a high molecular weight polyamide by polymerizing an oligoamide or polyamide obtained from an aromatic dicarboxylic acid, an aminocarboxylic acid, or a lactam while blowing an inert gas in a heat medium, after polymerization and/or after washing the polyamide, This method for producing polyamide is characterized in that a heating medium and/or a cleaning solvent are separated by filtration when hot using a porous body provided at the bottom of a reaction vessel. The heat medium used in the present invention means a thermally stable organic compound that can be treated as a fluid within the reaction temperature, and includes aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons,
It is one or a mixture of two or more compounds selected from ethers. Particularly preferred heat carriers in the present invention are heat carriers that swell polyamide at the reaction temperature but do not dissolve it, specifically methyldiphenyl,
Alkyldiphenyl such as dimethyldiphenyl, l-limethyldiphenyl, diethyldiphenyl, triethyldiphenyl, diphenyl ether, hydrogenated terphenyl,
Examples include alkylnaphthalene, cyclohexylbenzene, and decalin.

These heat carriers may be used after being purified by known methods such as distillation.

Specifically, the diamine, dicarboxylic acid, aminocarboxylic acid, and lactam used in the present invention include hexamethylene diamine, decamethylene diamine, dodecamethylene diamine, 2,2.4- or 2,4.4-trimethyl. Hexamethylene diane, 1.3- or 1.4
-Bis(p-aminomethyl)cyclohexane, bis(
Aliphatic diamines such as m- or p-xylylene diamine, dimethyl-p-
Phenylene diamine, chlorop-phenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'-
Aromatic diamines such as methylene dianiline and m-phenylenediamine; aliphatic dicarboxylic acids such as adipic acid, trimethyladipic acid, suberic acid, vimelic acid, azelaic acid, sebacic acid, dodecanedioic acid, undecanedioic acid, and cyclohexanedicarboxylic acid; isophthalic acid,
Examples include aromatic dicarboxylic acids such as terephthalic acid, aminocarboxylic acids such as 6-aminocabronic acid, 11-aξnoundecanoic acid, and 12-aminododecanoic acid, and ε-1-kabolactam, ω-1-dodecalactam, etc. , and are not limited to these, and various combinations of these may be copolymerized. Next, to specifically describe the method of the present invention, the salt consisting of the dicarboxylic acid and diamine, and/or the aminocarboxylic acid and/or the lactam are polycondensed by a known method to achieve a relative viscosity of 1.2 to 5.0. (Bori 7 >, I' l
g/LooJlg, 97% sulfuric acid solution, relative viscosity measured at 20"C), preferably 2.0 to 4.0. Next, the obtained boria ξ is molded into chips, Or crush it and heat it with a heating medium under normal pressure, reduced pressure or pressurization for about 100 ml.
Polymerization in a heat medium is carried out at ~300''C, preferably 150~250'C, by heating and stirring for about 10 to 50 hours while blowing an inert gas such as nitrogen gas, helium, carbon dioxide, etc.

The polymerization reactor used here is equipped with a porous body at the bottom that can be filtered and separated as shown in Figure 1, and the bottom of the polymerization reactor preferably has an angle of 45 degrees or 180 degrees. .

Although the reaction apparatus is not necessarily limited to the illustrated example, as illustrated in FIG. A porous body 5 is provided at the bottom of the filter, so that the heat medium and cleaning solvent after filtration can be extracted from the respective discharge ports 6 and 7, and the polymer after drying can be taken out from the polymer extraction port 8. structure can be adopted.

As the porous body, a metal plate with holes or a wire mesh with an appropriate opening can be used, and this porous body is preferably funnel-shaped as shown in the example, and is preferably in a format that allows efficient filtration. ．． After the polymerization is completed, the polymer and the polymerization heating medium are filtered off through the porous body. The separated heat medium is led to a container for waste heat medium, and a cleaning solvent is injected into the polymerization reaction vessel. As this cleaning solvent, for example, commonly used organic solvents such as acetone, toluene, xylene, and chloroform can be used. The cleaning efficiency increases as the amount of cleaning solvent used increases, but from the economical point of view it is preferably used in a range of 0.5 to 50@1 based on the polymer.

The conditions for washing are not particularly limited, but it is preferable to heat and stir the polymer and the washing solvent for several hours near the boiling point of the solvent used. The cleaning solvent after cleaning is filtered through the porous body, and the waste solvent is led to a waste solvent tank. It is preferable to rewash the polymerization reaction vessel by injecting a new washing solvent into it, and it is also preferable to repeat the above washing several times in order to reduce the amount of heat medium remaining in the polymer. With the above cleaning operation, the amount of heat medium remaining in the polymer is reduced to 0.
It will be less than 1%.

After the final cleaning operation, the cleaning solvent adhering to the polymerer is removed by drying with an inert gas. In order to increase drying efficiency, it is preferable to use an inert gas having a temperature equal to or higher than the boiling point of the solvent used. As for the type of gas, the one used in the polymerization reaction can be used as is. As described above, by employing the method of the present invention, it is possible to separate the heating medium, wash the polymer, and dry it efficiently using a polymerization reactor. It is also possible to provide two containers of the same type to perform polymerization, washing, and drying at the same time. Furthermore, it becomes possible to increase the size of the device and to make it continuous.

(Function) The function of the porous material used for separation in the present invention is as follows. Polyamide oligomers are dissolved in the heating medium after polymerization, and although they dissolve in the heating medium at high temperatures, they precipitate when cooled to room temperature. Therefore, it is necessary to quickly separate the polymer and the heat medium at high temperatures.

By providing a porous body as in the present invention at the bottom of the polymerization vessel, it is possible to quickly separate the polymer and the heating medium after polymerization, and it can also be used for iIt overseparation in the next polymer cleaning. I can do it.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example 1 A heated stirring reactor of 300-1 was equipped with a stainless steel wire mesh with an average pore diameter of 0.5 mm as a porous body at the bottom as shown in Fig. 1, and a polyamide resin with an average particle diameter of 2.1 smφ and a relative viscosity of 3.5 was placed in the heated stirring reactor. 25 kg of prolactam and 250 j2 of diphenyl ether/diphenyl (7/3) were charged.

5 & J nitrogen gas! /hr, raise the temperature while blowing 2
The mixture was heated and stirred at 00°C for 20 hours.

Next, the mixture was cooled to 80°C and filtered while hot through a porous body at the bottom.

Twice the amount of acetone was added to the polymer remaining in the reactor, and the mixture was heated and stirred for 1 hour at the boiling point of acetone. After the end,
It was also filtered while hot through the porous material at the bottom. After performing this polymerer cleaning operation four times, dry nitrogen gas at 150°C was blown into the bottom to dry it.

The relative viscosity of the polyamide after drying was 14.5.

Example 2 Using the same equipment as in Example 1, the average particle size was 2. lmφ, polyhexamethylene adipamide 25k with relative viscosity 2.82
g, and 250 N of diphenyl ether were charged.

While blowing nitrogen gas at 5M/hr, the temperature was raised to 235
The mixture was heated and stirred at °C for 20 hours. Next, the mixture was cooled to 80° C. and filtered while hot through a porous body at the bottom.

Twice the amount of acetone was added to the polymer remaining in the reactor, and the mixture was heated and stirred for 1 hour at the boiling point of acetone. After the end,
Similarly, it was filtered while hot through the porous material at the bottom. After performing this polymerer cleaning operation four times, 150'
It was dried by blowing dry nitrogen gas in step c.

The relative viscosity of the polymer after drying was 16.5. (Effects of the Invention) By employing the method of the present invention having the above structure, l. After polymerization, it becomes possible to quickly separate the polymer and heat medium, making it possible to obtain a high-quality polymer. 2. It becomes possible to use the polymerization reaction vessel as is for polymer cleaning. 3. It can also be used to dry polymers. 4. This makes it easier to increase the size of the device and reduce costs. Various advantages arise, such as, and it will greatly contribute to the industrial world.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of one embodiment of a reaction apparatus used in carrying out the method of the present invention. 1 is a stirrer, 2 is an inert gas inlet, 3 is a waste gas outlet, 4 is a reaction vessel, 5 is a porous body, 6 is a heat medium outlet, 7 is a cleaning solvent outlet, and 8
indicates the polymer outlet.

Claims (1)

[Claims] A high molecular weight polyamide is obtained by polymerizing an oligoamide or polyamide obtained from an aliphatic and/or aromatic diamine and an aliphatic and/or aromatic dicarboxylic acid, an aminocarboxylic acid or a lactam in a heating medium while blowing an inert gas. During production, after polymerization and/or washing of polyamide, a porous body provided at the bottom of the reaction vessel allows
A method for producing polyamide, which comprises separating a heating medium and/or a cleaning solvent by filtration while hot.