DE1252896B - Process for the production of polyurethanes - Google Patents

Description

Process for the production of polyurethanes It is known, organic Molecules with one or more isocyanate groups with organic compounds with implement one or more OH groups. This gives urethanes. Basically it is possible to use all alkali metal replaceable H atoms in organic molecules to add isocyanate groups.

If the diisocyanates are reacted with glycols, linear ones are obtained Polyaddition products that are meltable and especially in the low molecular weight range often in organic solvents, e.g.

Chlorobenzenes, nitrobenzene, are soluble. They are thermoplastic deformable. The polyurethanes can be used in the paint industry as well as for production of threads, bristles and injection molded articles.

Polyisocyanates and glycols or diisocyanates and polyalcohols or Polyisocyanates and polyalcohols react with one another to form crosslinked, infusible ones Masses that are insoluble in solvents. The closer in the molecule the cross-linking Groups lie on top of one another, the more rigid the plastic becomes. However, are the networking points far enough apart so that soft rubber-like plastics can be obtained.

The patent application relates to a process for the production of polyurethanes by reacting compounds containing isocyanate groups with compounds containing OH groups, characterized in that the isocyanates are compounds of the formulas can be used in which R denotes identical or different alkyl groups, in particular methyl groups.

The diisocyanates which are used according to the invention arise in the reaction of 2,2'-dimethylffimethylhexamethylenediamine and / or 2-methyl - 4,4'-dimethylhexamethylenediamine with hydrogen chloride or carbon dioxide and then implementation of the resulting reaction product with phosgene, optionally in the presence of a organic solvent. These compounds can be used to produce thermoplastics with glycols, e.g. B. ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, or all of them any dialcohols, which are also isocyclic, aromatic, heterocyclic or also linear hetero groupings, e.g. B. Ester groups, sluggish can implement. These compounds can be used as diisocyanates alone or in the presence other iso-, diiso- or polyisocyanates can be used. With the polyisocyanates this means that cross-linked plastics that can no longer be thermoplastically deformed can be created. A reaction is also possible with polyalcohols or dialcohol-polyalcohol mixtures infusible masses possible.

Depending on the type and amount of crosslinking, both solid, brittle masses as well as plastics with rubber-elastic properties produce. Of course, all of these polymers can be used with the usual Add fillers such as carbon black, aluminum, talc, wood flour, and also dyes.

The addition of glycols or polyalcohols to diisocyanate can can be carried out without a diluent, depending on the reaction components 50 to 300 ° C. It is also possible to work in diluents, for example halobenzenes.

Depending on the molar ratios, the components, dissipation of the heat of reaction from the melt, increase in residence times in the dissolved state, addition of monofunctional, chain-breaking components, one can determine the molecular weight in a manner known per se of the polyurethane vary. In general, for plastics it is necessary above of the average molecular weight of 6000 to polymerize. Low molar types are primarily used for paints.

The water absorption capacity of these polyurethanes is lower than that the corresponding polyamides.

The incorporation of benzene nuclei into the chain of alcohols results in more brittle ones Products and the brittleness can be compensated for by a longer CH2 chain.

By using a mixture of different glycol components the melting point of isocyanates decreases, while their solubility in hydrocarbons increases. You have a vastly larger thermoplastic area, a larger one Softness and also better compatibility with plasticizers.

The claimed isocyanates also make it easy to bake enamels manufacture with polyalcohols. The activity of the isocyanate groups is mostly not so great that the risk of swelling of the undiluted mixtures of polyalcohols and the diisocyanate at room temperature, especially when using organic Carefully excludes bases, alkali and heavy metal salts.

It can also be used with the diisocyanate and carboxyl-containing substances make foams as usual.

EXAMPLE All of the polyurethanes listed in the table below were prepared by adding trimethylhexamethylene diisocyanate (isomer mixture about 1: 1) to the alcohols listed below in a molar ratio of 11 (-OH: -NCO group) under dry nitrogen. The reaction temperature was initially held at 100 "C for 4 hours and then increased to 170" C for a further 5 to 8 hours Alcohol | properties of the polyurethanes a) 1,4-butanediol brittle, hard, transparent b) 1,6-hexanediol hard, transparent c) Decanediol-1.10, medium hard d) Dipropylene glycol, medium-hard, transparent e) Triethylene glycol transparent f) 3-methyl-2,4-pentanediol hard, transparent g) 1.6-trimethylhexanediol hard, transparent h) polyester, consisting of elastic, transparent 0.39 mole percent ethylene glycol 0.01 mole percent glycerin 0.1 mole percent propylene glycol 0.5 mole percent adipic acid SZ = 9 OH number = 72 i) Polyester, consisting of soft, transparent 0.49 mole percent ethylene glycol 0.01 mole percent glycerin 0.5 mole percent adipic acid SZ = 3.5 OH number = 84

Claims (1)

Claim: Process for the production of polyurethanes by reacting compounds containing isocyanate groups with compounds containing OH groups, characterized in that the isocyanates are compounds of the formulas can be used in which R is identical or different alkyl groups, in particular methyl groups. Documents considered: German Auslegeschrift No. 1090196; Belgian patents nos. 548 884, 548885.