SU613849A1 - Complex activator for sands based on carbamide-furane binders for making casting moulds and cores and method of preparing same - Google Patents

Description

For LDPE: the purpose of this goal is to prepare this complex activator, including dissolving the ingredients in water, mixing them, the hallmark of which is preparing aqueous solutions of ammonium sulphate nitrate and then mixing them, adding an aqueous solution alcohol-alcoholic bards and stirred {the composition until a homogeneous state is reached. For the preparation of the proposed complex activator, it is advisable to use Eating technical products: Calcium nitrate technical, (th (STU-71-X-20-6 ammonium sulfate technical (GOST 9097-65) Sulfite-alcohol bard (GOST 8518-57) With the content of calcium nitrate, ammonium sulfate and sulfite-alcohol bards in the composition of the complex activator is lower than the lower or higher than the above specified limits, a decrease in strength, an increase in the scattering of rods and molds and a decrease in the vitality of the mixtures is observed. The proposed method for the preparation of a complex activator involves the following order of ingredients dissolution and their mixing Vani. Calcium nitrate, ammonium sulphate and sulphite-alcohol stillage are dissolved in water at room temperature. Each ingredient is dissolved separately in the mixers. After complete dissolution of the salts, their solutions are poured into one container and stirred for 10-15 minutes. Then, the calculated amount of sulphite-alcohol stillage solution is introduced and, if necessary, the total content of water in the activator is adjusted. After that, the entrapment of the activator is continued for 2-3 lsn. The total mixing time is 12-18 minutes. The complex activator is recommended to be prepared for a week of work. The procedure for preparing the complex activator is explained as follows. At the joint dissolution of the components in water and their mutual mixing, an interaction occurs between calcium nitrate and gshmonium sulphate to form calcium sulfate. Due to the hardening effect of calcium sulfate crystalline hydrate (gypsum), the vitality decreases and the strength of the mixture in the cheese state increases, which creates difficulties in the formation of rods using shotgun or sandblasting methods. Upon separate dissolution of the components, the solvation of the corresponding ions of the salts of molecular waves occurs, making it difficult for them to interact chemically during the subsequent mixing of the solutions. With the introduction of sulfite-alcohol stillage, the stability of salt ions is enhanced, since the latter are blocked by the high molecular weight components of lignosulfonates. Therefore, the vitality is greatly increased and the strength of the mixture in its raw state decreases. An example. As described above, a complex of the complex activator according to the present invention is prepared (for compositions, see Table 1). In addition, the lime method is used to prepare the catalyst 21-37 (composition - see table. 1). To assess the effectiveness of the proposed activator, mixtures were prepared on a carbamide-furan binder KF-40 (TU-6-05-1614-73). The curing temperature of standard samples obtained from mixtures was 170–200 ° C, the curing time was 20–25 s. During the curing of the samples from the mixture with the catalyst 21-37 (according to the chosen prototype), the temperature of the equipment was 220-250 ° C. All mixtures were prepared using as a refractory filler, taken in a 1: 1 weight ratio of two quartz sands: Kichiginsky (U0315) and Nizhneuvelsky (K016) deposits. The compositions of the tested mixtures were identical and included 3 wt. % carbamide-furan resin KF-40, 0.7 wt.% of complex activators (1, 2 or 3 (the compositions of the latter - see Table 1) or (for comparison) 0.7 wt.% of catalyst 21-37, and the specified refractory filler is also indicated (the rest is up to 100 wt.%). The test results are given in Table 2. Thus, the proposed complex activator provides the following advantages: - increased mixture survivability; (due to the flow in the process, heat treatment of chemical shares with the formation of gypsum); -decrease of the heating temperature of the equipment from 220-250 0 to 170-200C; -decrease in the gas-making ability and shedding of mixtures. In addition, ammonium nitrate, processing: pc) | chemically bind free formaldehyde, produced by the resin, which improves the hygienic working conditions at work sites.

Table 1

Calcium Nitrate

Sulphate gmmmoni

Sulfite-alcohol bard

Urea

Ammonium nitrate

Chalk ssa

Water

36.8 5.0

2.5

.37

-21

-21

55,721

Table