Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
  • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
  • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
  • C08G69/28—Preparatory processes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/41—Preparation of salts of carboxylic acids
  • C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part

Definitions

• the invention relates to a process for the preparation of highly concentrated aqueous solutions of salts from dicarboxylic acids and diamines and polyamide precondensates by reacting alkanedicarboxylic acids with 6 to 12 carbon atoms and diamines with the formula NH2R NH 2 , in which R denotes an alkylene radical with 6 to 12 carbon atoms or the rest mean.
• aqueous salt solutions of dicarboxylic acids and diamines are generally used.
• DT-PS 1 060 139 and DT-AS 11 58 257 it is generally assumed that 45 to 70 percent by weight salt solutions are used.
• the technical task was to provide starting solutions for the production of polyamides from dicarboxylic acids and diamines which are easy to handle and contain as little water as possible and which make it possible to utilize the thermal energy contained in the starting solutions.
• This object is achieved in a process for the preparation of highly concentrated aqueous solutions of salts from dicarboxylic acids and diamines and polyamide precondensates by reacting alkanedicarboxylic acids with 6 to 12 carbon atoms and diamines of the formula NH 2 RNH 2 , in which R is an alkylene radical with 6 to 12 carbon atoms or the rest means, characterized in that aqueous salt solutions of dicarboxylic acids and diamines of lower concentration, which contain a corresponding amount of the respective dicarboxylic acid in excess, are reacted with the respective molten diamine in equivalent amounts based on the dissolved dicarboxylic acid, with the proviso that the reaction under carried out increased pressure and a final temperature of 140 to 210 ° C is maintained during the reaction.
• the new process has the advantage that it immediately leads to highly concentrated aqueous starting solutions for polyamide production, which no longer need to be concentrated.
• the new process also has the advantage that starting solutions are obtained in which the heat of neutralization contained is used for the polycondensation.
• the new process has the advantage that the starting materials can be metered and mixed easily.
• alkane dicarboxylic acids with 6 to 12 carbon atoms are used.
• Straight-chain ⁇ - ⁇ -dicarboxylic acids of the stated carbon number are preferably used.
• Suitable dicarboxylic acids are, for example, adipic acid, Suberic acid, azelaic acid, sebacic acid, decanedioic acid and dodecanedioic acid. Adipic acid and sebacic acid have acquired particular technical importance.
• diamines of the formula NH 2 RNH 2 are used , in which R is an alkylene radical having 6 to 12 carbon atoms or the radicals designated. Straight-chain ⁇ - ⁇ -alkanediamines having 6 to 12 carbon atoms are particularly preferably used.
• Suitable diamines are, for example, hexamethylene diamine. Octamethylene diamine, decamethylene diamine, dodecamethylene diamine, bis (4-aminocyclohexyl) methane or bis (4-aminocyclohexyl) propane-2,2. Hexamethylenediamine has gained particular technical importance. Accordingly, solutions of salts and polyamide precondensates which are derived from adipic acid or sebacic acid and hexamethylenediamine are also preferred process products
• the starting point is an aqueous salt solution of dicarboxylic acids and diamines of lower concentration, which contains a corresponding amount of the particular dicarboxylic acid dissolved in excess. Solutions which contain 40 to 65 percent by weight, in particular 50 to 65 percent by weight, of the respective salts, based on the sum of salt and water, are advantageously used. The amount of dissolved dicarboxylic acid depends on the desired final concentration of the highly concentrated aqueous solutions to be prepared.
• solid dicarboxylic acid is dissolved in a salt solution of lower concentration. Temperatures of 60 to 110 ° C are generally maintained. Salt solution thus obtained containing free dicarboxylic acid is then reacted with molten diamine in equivalent amounts based on the dissolved dicarboxylic acid. It is advantageous to ensure that the pH value for the equivalence point of the salt to be produced is observed.
• the equivalence point for hexymethylene diammonium adipate is pH 7.62 and for hexamethylene diammonium sebatcat pH 7.5 measured in 10 percent aqueous solution at 25 ° C.
• the reaction is advantageously carried out in a mixing section, first adding a small deficit of molten diamine and then carrying out the precise adjustment by adding molten diamine again.
• diamines are generally used in excess, e.g. up to 1.5 mole percent.
• solid dicarboxylic acid is first dissolved in an aqueous solution of diamine in deficit.
• a salt solution of dicarboxylic acid and diamine which contains an excess amount of dicarboxylic acid in solution.
• the dicarboxylic acid is advantageously dissolved at temperatures of 60 to 110 ° C., where you usually maintain atmospheric pressure.
• the salt solution thus obtained containing free dicarboxylic acid is then melted with diamine in equivalent amounts based on dissolved di implemented carboxylic acid. This implementation is advantageously carried out as described in the aforementioned procedure.
• Polyamides which are produced from the solutions according to the invention are suitable for the production of masses shaped from the melt, such as threads, fibers, moldings, plates or coatings.
• the example shows the use of part of the heat of neutralization to dissolve the dicarboxylic acid.
• the flask was immersed in a water bath at 75 ° C acting as a protective heater; immediately thereafter, a solution of 75 g of hexamethylenediamine in 92 g of water, kept in the dropping funnel at 90 ° C., was added with stirring within 20 seconds. After 2 minutes a clear solution had formed, the temperature of which was 69 ° C.
• the composition of the solution was 37% AH salt, 43% adipic acid and 20% water.
• the further implementation was carried out analogously to Example 1.
• the AH salt solution obtained in Example 1 was polycondensed without cooling the solution. It was heated to 275 ° C. in the course of 3 1/2 hours, the pressure being kept at 19 bar by blowing off steam. After reaching 275 0 C was laid over 1 hour at normal pressure and postcondensed 1 hour to 273 ° C. The product was pressed out of the autoclave under nitrogen pressure, with the melt strand in a water Bad cooled and granulated.
• the polyamide 66 obtained had a relative viscosity of 2.54, measured in 1 percent solution in 96 percent sulfuric acid, and a content of acidic groups of 54 meq / kg and of basic groups of 76 meq / kg.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Polyamides (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1977
  • 1977-06-27 DE DE19772728817 patent/DE2728817A1/de not_active Withdrawn
• 1978
  • 1978-06-08 US US05/913,641 patent/US4213884A/en not_active Expired - Lifetime
  • 1978-06-16 DE DE7878100175T patent/DE2860572D1/de not_active Expired
  • 1978-06-16 EP EP78100175A patent/EP0000157B1/fr not_active Expired
  • 1978-06-20 IT IT24766/78A patent/IT1096586B/it active
  • 1978-06-26 JP JP7659178A patent/JPS5412316A/ja active Granted

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