Sodium dicaprolactamato-bis(2-methoxyethoxy)aluminium hydride NaAl[N(CH2)5CO]2(OCH2CH2OCH3)2 - is used for anionic polymerisation and copolymerisation of lactams over a wide range of temperatures.
DILACTAMATE KATCHEM initiator also serves as a drying agent and allows the use of technical caprolactam (moisture content up to 0.03 wt. %) as a raw material for the production of polyamide.
One of its main advantages over other types of initiators is its very high tolerance for caprolactam impurities, including moisture. This advantage opens up many new possibilities for improving various polymerization technologies.
Benefits of using DILACTAMATE KATCHEM
DILACTAMATE KATCHEM is commercially available in the form of a toluene solution (min. active ingredient content 80%) and the application and dosage are therefore very simple. The reaction mixture is obtained by simply dissolving the initiator in the molten monomer.
With a humidity of up to 0.03 wt.% and an initiator/activator = 1, a suitable dose of DILACTAMATE KATCHEM of about 0.3 mol. % appears.
Use of DILACTAMATE KATCHEM enables the almost wasteless production of polyamide-6 castings by the direct polymerisation of 6-caprolactam in stable or rotational forms. The polymer mixture is usually heated to 135 - 145oC and DILACTAMATE KATCHEM is added just before it is poured into the moulds. The choice of mould temperature depends on the size of the casting, the composition of the catalytic system and the type of activator used (isocyanates, N-aryl and N-acetyl lactam), the initiator/activator ratio and the amount used. The temperature is usually in the range of 160 - 170oC. Under these conditions, the polymerisation process lasts from a few minutes to tens of minutes. The tempering of castings is carried out in the usual way.
This product was developed as a special initiator for the delaying the crystallization phase of polymerisation, especially in the production of polymers reinforced with glass or carbon fibre.
Reasons to use DILACTAMATE KATCHEM S
Two factors contribute to the increase in temperature during the polymerisation process: the exothermic polymerisation reaction and the exothermic crystallisation of the polymerised product. If both processes reach their peak at the same time, rapid polymerization contraction and local overheating inside the larger casting cause a higher probability of holes in some castings. It is therefore desirable to separate the maximum temperature peak of the exothermic polymerisation from the maximum temperature peak of the crystallisation.
The purpose of the DILACTAMATE KATCHEM S is to ensure delay of the crystallising maximum during the polymerisation process. The "relaxation" time between the end of the polymerisation phase and the temperature peak of the crystallisation process allows for slower compensation of the internal stresses of castings due to polymerisation volume contraction.
Using DILACTAMATE KATCHEM S, crystallization maximum delay is usually equal to 17 minutes or more.
DILACTAMATE KATCHEM S is a dilactamate containing small amounts of magnesium caprolactamate. This amount is less than 0.2% wt., so it can be considered as an impurity from the SDS point of view.