SU1565567A1 - Antistick coating for moulds and cores - Google Patents

Abstract

This invention relates to a foundry, namely, compositions for producing nonstick coatings for casting molds and cores. The purpose of the invention is to improve the quality of the coating by increasing the penetrating power and reducing the cost of the coating. The composition of the coating, the following wt.%: Refractory filler / talc / 25 ... 40, polyvinyl acetate dispersion 13 ... 14, nitrolignin 3 ... 5, epoxy-Dianova resin 3-4, plasticizer formate-alcohol / PPS / on Based on sodium formate solution, a by-product in the production of pentaerythritol is 5 ... 7, water is the rest. The implementation of the coating makes it possible to increase the penetrating ability of the coating by 1.2 ... 1.7 times, which contributes to the hardening of the surface of casting molds and cores, reducing scrap due to blockages, and also increases the sedimentation stability of the paint by 3.2 - 3.8 % 3 tab.

Description

The invention relates to foundry, in particular, compositions for producing non-stick coatings of casting molds and cores in the production of predominantly cast iron castings.

The purpose of the invention is to improve the quality of the coating by increasing its penetrating power and reducing the cost of the nonstick coating.

The essence of the invention is as follows.

Talc is used as a refractory filler. Polyvinyl acetate homopolymer coarse dispersed PVAD is used as a film former.

The nitrolignin contained in the coating is a brown paste with a moisture content of 40%. Its main area of application is the oil and gas industry, where it is used as an effective regulator of the structural and mechanical properties of clay solutions. Nitrolignin provides a suspension with a high sedimentation stability and contributes to the formation on the surface of the forms and rods of a uniform thickness of the antistick layer. In addition, nitls

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Rolignin promotes better wetting of the surface of the mold with the obtained suspension, migration of the dispersion medium into the pores of the molding mixture, which increases the depth of impregnation of the mold and ultimately increases the strength of the surface layers of the coating and the mold.

To increase the strength of the coating, epoxy resin (mol.m. 370-600) according to GOST was introduced into its composition.

The proposed nonstick coating does not contain fire-hazardous components. The forkyate-alcoholic (PPS) plasticizer, which is part of the coating, is an aqueous solution of sodium formate, syrup-forming substances and polyalcohols (monopentaerythritol and polypentaerythritol).

Technical characteristics of the SFC are listed in Table. one.

Polyalcohols in syrup-forming substances, which are part of the SFC, contribute to better wetting of the surface of the molds and rods with this composition, migration of the dispersion medium into the pores of the molding sand, which ultimately makes it possible to increase the depth of impregnation of the molds and rods. In addition, the plasticizing properties of the additive allow the forms and cores to form on the surface of the nonstick layer on the surface. PPS is a by-product of pentaerythritol production, therefore its use in the composition while reducing the percentage of expensive components used (nitrolignin and polyvinyl acetate dispersion) leads to a reduction in the cost of coating. Plasticizer formate-alcohol (aqueous solution)

fire and explosion safe belongs to the toxicological hazard class (low hazardous), has a weak general toxic effect.

The invention is illustrated by coating compositions and their physico-mechanical properties, which are listed in Table. 2 and 3. In table. 2 shows the compositions of nonstick coatings (No. 1-5 proposed and No. 6 known), which are prepared for testing. In tab. 3 shows the properties of nonstick coatings.

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Coatings No. 1-3 (Table 2) are prepared as follows.

Any type of sprayer is filled with prescription quantities of PVAD and epoxy resin. The mass is mixed for 30 minutes until complete combination of PVAD and epoxy resin. According to the JQ of the emulsification processes

The mixer is loaded sequentially in the formulated PPS quantities. water, nitrolignin and talc. The loaded components are mixed for 30-40 minutes until a homogeneous mass is obtained. The coating can then be further dispersed on a three-roll paint-spraying machine and packaged in containers.

The implementation of the invention will increase the penetrating ability of the coating due to the introduction of SFCs 1.2–1.7 times, which contributes to the hardening of the surface of casting molds and cores, reducing scrap due to fouling, as well as increasing the sedimentation stability of the paint by 3 , 2- 3.8%. The coating is stored for a long time without additional mixing.

PPS is a by-product of pentaerythritol production, therefore its use in the composition while reducing the percentage of the expensive components used (nitrolignin and polyvinyl acetate dispersion) leads to a decrease in the cost of the coating.

Claims (1)

Invention Formula Nonstick coating for casting molds and cores, including talc, polyvinyl acetate dispersion, nitrolignin, epoxy resin, and water, characterized in that, in order to improve the quality of the coating by increasing its penetrating power and reducing the cost, the coating additionally contains a formate-alcohol plasticizer Based on sodium formate solution, a by-product of pentaerythritol production in the following ratio of ingredients, wt.%: Talc 25-40 Polyvinyl acetate dispersion 13-14 Nitrolignin 3-5 Epoxy-Dianova resin Plasticizer formate-alcohol 15655676 formate based on sodium formate solution Water Table t Performance Appearance I Norm Dark brown liquid with sediment in the form of a fine suspension M.d. dry residue,%, not less than 35 Md ash,%, no more than .22 Md sodium formate,%, not more than 25 ppm polyalcohols in terms of pentaerythritol,%, in limits 5-10 Hydrogen ion concentration, pH 6-8 table 2 Components Content Components May. % in coatings .JUNY Talc .4030 25 Polyvinyl acetate dispersion PVAD1313,5 14 Nitrolignin345 Epoxy Dianova resin33.5 4 Plasticizer formate-alcohol567 Water3643 45 Table Indicators The values of indicators coverings 1 2 G 3 Density, g / cm3 1.45 1.44 1.43 Covering abilityGood Good Good Good penetration depth of the coating, mm17-18 17-18 17-1 Sedimentation stability,%, after 3 h 99.2 99.5 99.8I Norm