Method for producing polyamide
A polyamide and diamine technology, applied in the field of polyamide production, can solve the problems of easy contact with oxygen, easy absorption of metal impurities, oxidation and decomposition of monomeric carboxylic acid, shortening residence time, increasing molecular weight, and improving polymerization. degree of effect
Inactive Publication Date: 2012-01-11
卢建国
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Problems solved by technology
If the method of first melting the dibasic acid is adopted, long-time heating and higher temperature are required, and the following problems are prone to occur: the monomeric carboxylic acid is easy to contact with oxygen, and oxidation and decomposition occur; Contact, easy to absorb trace metal impurities; and need to take measures to avoid sublimation, etc., there are considerable difficulties in the actual application process
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[0032] In the following examples, the intrinsic viscosities [η] of polyamide prepolymers and endpolymers were determined by the following methods and standards.
[0033] The intrinsic viscosity [η] of polyamide was measured by the method specified in standard ISO307. which is:
[0034] Dissolve the polyamide sample to be tested in 96% concentrated sulfuric acid to obtain a solution with a concentration of 0.05, 0.1, 0.2 or 0.4g / dl, and measure the inherent viscosity η of each sample solution at 30°C rlh as follows:
[0035] n rln =[ln(t / t 0 )] / C (dl / g)
[0036] where t 0 represents the flow time (seconds) of the solvent, t represents the flow time (seconds) of the sample solution, and C represents the concentration of the sample in the sample solution.
[0037] Will η rln The data were extrapolated to the concentration range of 0 to obtain the intrinsic viscosity [η] of the sample.
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Abstract
The invention discloses a method for producing polyamide. The method comprises the following steps: 1, adding a molten diamine to a solid dicarboxylic acid without a solvent, forming a mixed solution of the dicarboxylic acid and the diamine or a suspension with good fluidity in a first polymerization reactor, and forming a prepolymer of polyamide with the inherent viscosity of 0.3-0.7dl/g in a second polymerization reactor; and 2, granulating the prepolymer with a double screw extruder with at least two vent holes, adding prepolymer particles to a solid phase polymerization reactor of a fixedbed, heating the prepolymer particles with hot nitrogen with a certain flow and a certain temperature, reacting for 1-15h to obtain products of polyamide with the inherent viscosity of 1.0-2.5dl/g. Compared with previous polyamide polymerization methods, extra energy costs needed by solvent removal are reduced and the operation cost is reduced because polycondensation is carried out without the solvent; energy consumption in the melting process is reduced and possible problems of raw material oxidation and the like caused by a high melting temperature are avoided because cases that the diamine and the diacid for polyamide production have different melting points and the melting point of the diamine is low, and the molten diamine is added to the solid diacid are skillfully used in the method of the present invention.
Description
technical field [0001] The present invention relates to a method for producing polyamide from dibasic carboxylic acid and dibasic amine as monomers. The method is to continuously or discontinuously add molten dibasic amine into solid dibasic carboxylic acid under the condition of no solvent Melt polymerization is directly realized to obtain a polyamide prepolymer with a certain intrinsic viscosity, and then the molecular weight of this prepolymer is increased by solid-state polycondensation, and finally a polyamide polymer that meets actual needs is obtained. Background technique [0002] Polyamide (nylon) such as nylon 6, nylon 66 and nylon 610 are engineering plastics widely used in many fields. Some nylon varieties, such as nylon 66, nylon 610, etc., are usually produced by dicarboxylic acid and diamine in the presence of solvents (such as water, ethanol, etc.) to make nylon salt, and then use nylon salt solution according to batch or continuous production. . For exampl...
Claims
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IPC IPC(8): C08G69/28C08G69/36
Inventor 卢建国
Owner 卢建国
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