SU657903A1 - Composition for moulds and cores made in heated equipment - Google Patents

Description

Nepheline flame retardant (1U b-08-321-75) is an inorganic finely dispersed material whose composition corresponds to the molecular formula 1.25 (NH) j О 0.92 (Na, 0 + KjO) AEjOj- 0.1 FejOj 3.5 PjOj 2,5S1O2. It is mixed aluminum, sodium, potassium, and electrooammonium phosphates in pyro-, Tripoli-, tri-beta-forms and contains, weight.%: Not less than 48.0 (total) ( water solution.) Not more than 2, 5 Rjpj (Aejp | -Fej03) 12-15 Not less than 4.3 8-10 (NajO + KjO) Moisture content Not more than 3.0 Increase the strength of the mixture is achieved due to the distribution of the resin in a thin film in the presence of a fine additive - nepheline flame retardant, an additional strengthening of the mixture in the result of the interaction of the resin during heating with soluble phosphates formed upon contact of the nepheline flame retardant with the aqueous phase of the mixture, and the complexing effect of the insoluble aluminum phosphates contained in the nepheline flame retardant. The formation of insoluble metal-phosphate-resin complexes simultaneously increases the thermal stability of the mixture. The vitality of the mixture is increased due to the low content of the liquid catalyst, for example an acid solution. The advantage of the proposed mixture is also the possibility of using quartz sand with a clay content of up to 1.0% inclusive. The manufacturing techniques of the proposed mixtures do not differ from the manufacturing techniques of the known hot-curing mixtures containing urea-formaldehyde resins, the filler is poured into the mixer, then the nepheline fire retardant is introduced simultaneously with the curing catalyst and mixed for 1 minute. The resin is then added and all components are mixed for another 1 minute. Table 1 shows examples of the composition (wt.%) Of the mixture; in table 2 - the properties of mixtures containing Ai eline fire retardant (compounds 1-4); For comparison, the composition and properties of a known mixture containing a carbohydrate-protein hydrolyzate (composition 5) are given. Strength properties of mixtures and. survivability is determined by a known method. The optimum content of nepheline flame retardant in the mixture is 0.21, 0 wt.%. With a lower content, the strength properties of the mixture in a hot and cold state decrease, and with a larger content, the strength properties of the mixture do not improve. The heat resistance of the mixtures is characterized by the heat resistance of the cured composition (resin + additive + catalyst), which is determined by the weight loss in percent when the sample of the cured composition is heated. Comparative data on the heat resistance of the known and proposed mixtures are given in table 3. The proposed mixture, as compared with the known one, has an increased strength (in the hot and cooled state), heat resistance and living-: honor. When using the proposed mixture, the number of breaks in the rods when they are removed from the crate and the castings are rejected for cuttings and cuts is reduced, the surface quality of the castings is improved, and the range of application of mixtures of hot, curing based on urea-formaldehyde resins is expanded. Table 1

96, 785 96,585 96,385.95,985 96.8

3.03.0 3.03.0

0,015 0,015 0,0150,015 0.2

1.8

Nepheline flame retardant 0.2

Carbohydrate-protein hydrolysis. Strength of specimens during stretching in the hot state (box-190-210 ° C, holding time 60 seconds), kgf / cm

Strength at stretching of cooled samples, kgf / cm

0.4 0.6 1.0

1.2 T a b and c a 2.

9.0- 11.0 10.0 5.0 - 6.0 10.0

30.0 30.0- 29.0- 25.0-27.0 31.0 30.0

Table3