RU2227080C1 - Emulsion type heat hardenable binder for making casting molds and cores - Google Patents

Abstract

FIELD: compositions of molding sands for making casting molds and cores solidified at heat treatment. SUBSTANCE: binder contains, mass%: tall pitch, 25 - 28; hydrocarbon dissolver, 0 - 17; lignosulfonates on conversion to dried matter, 20 - 21; non-ionogenic surface active matter, 8 - 10,5; water, the balance. Surface active matter is product of oxyethylation of organic alcohols, acids and their mixtures having 2 - 10 oxyethyl links. EFFECT: enhanced uniformity of stable emulsion, high strength of casting molds and cores made at using molding sand non-sticking to fitting. 1 tbl, 5 ex

Description

The present invention relates to the field of foundry, namely, binders used in mixtures for the manufacture of foundry cores and molds, cured by heat treatment. The present invention can be used in foundries, engineering, chemical and other industries.

Quite stringent requirements are imposed on thermal curing binders for the manufacture of foundry cores and molds. They should provide high strength of the rods: for compression in the wet state 0.12-0.20 kgf / cm ² , and for tension in the dry state (after drying) in the range of 12-20 kgf / cm ² . In this case, the mixture should not stick to the tool during the manufacturing of the rods (and molds), especially when using the so-called sandblasting method.

Known casting binders for thermal curing [Molding materials and mold technology: Reference book / S. S. Zhukovsky, G. A. Anisovich, N. I. Davydov and others: Under the general. ed. S.S.Zhukovsky. - M .: Mashinostroenie, 1993. - 432 p.], Which are mostly bottoms from the distillation of synthetic fatty acids in organic solvents, most often in white spirit, such as USK-1, KO, SKT-10, etc. All of them are water-insoluble, require the use of additional introduction into sand or sand-clay mixtures, as a rule, lignosulfonates and the strength of the rods and forms is relatively small.

It is also known emulsion binder of thermal hardening for the preparation of foundry molds and cores containing an aqueous solution of lignosulfonates, an organic solvent (white spirit), and a fastener (binder) based on the residual products of distillation of oil products, namely, oxidized petrolatum [V.A. Sokolova. Quick-drying emulsions of sulfate stillage as a binder. / Sat “Molding materials”. -M .: Mashgiz, 1954. - p. 94-105.]. The specified binder when used in the compositions of molding mixtures provides a sufficiently high strength in the wet state (0.15-0.35 kgf / cm ² ). However, their strength after thermal drying is low and does not exceed 8 kgf / cm ² .

Binders are known for molding and core mixtures in which tall pitch is used as a binder (fastener) - a by-product from the production of pulp by the sulfate method.

In particular, the known composition [German Patent No. 1263224. Kl. 31 In 1/24, 1968.] includes (in parts by weight):

Tall (sulfate) pitch 55

Abietin resin treated with 0.05 parts by weight iron salts 30

Solvent (turpentine) 15

The main drawback of the known binder is the practical absence of abietin resin (a product of processing dried spruce resin), and the use of turpentine, the vapor of which has a strong irritating effect on the skin, causing eczema in workers, as well as lung damage, despite their protection. A binder based on tall pitch is also known [Auth. St. USSR No. 687679. Kl. ² B 22 C 1/24, 1977.], which is a solution of tall pitch (50-90%) in an organic solvent (10-50%): hydrocarbons, or alcohol, or ketones, or ether of acetic acid, or mixtures thereof. This binder is called “TOP”.

This binder provides molds and cores of the required strength. However, it is not without flaws. Of these solvents, only hydrocarbons that do not have a phenyl core in their structure meet environmental requirements.

The main disadvantage of the “TOP” binder is its adherence to the used technological equipment, which causes considerable difficulties and makes it practically impossible to use it for forming rods, especially by the sandblasting method on semi-automatic lines.

The closest in technical essence and the achieved result is an emulsion binder [Ed. Union of the USSR No. 700995. Kl. ² B 22 C 1/24, 1977 (prototype)], containing (wt.%):

Organic Solvent 14-28

Tall pitch 32-66

Water-soluble lignosulfonate - in terms of dry matter Else.

The composition of the prototype provides the production of molds and cores of the required quality and does not cause the mold to adhere to the snap. However, this composition is not without drawbacks, the main of which is the instability of the composition and its heterogeneity. The reason for this is that this composition is emulsion, but the emulsion is not stable and exfoliates into the aqueous and organic layers not only during storage, but also during use. The latter circumstance causes the practical impossibility of using this emulsion composition in production.

The aim of the invention is to increase the stability of the emulsion binder and improve its technological properties while maintaining high strength characteristics of manufactured molds and cores.

To achieve this goal, we offer an emulsion binder of thermal cure for the manufacture of foundry cores and molds, including water-soluble lignosulfonates, an organic solvent and tall pitch, characterized in that it additionally contains a non-ionic surfactant, which is a product of the hydroxyethylation of organic alcohols, acids or mixtures thereof with the number of hydroxyethyl units 2-10 in the following ratio of ingredients (in wt.%):

Tall pitch 25-28

Hydrocarbon solvent 0-17

Lignosulfonates (in terms of dry matter) 20-21

Nonionic surfactant 8-10.5

Water Else

To obtain the proposed binder of thermal curing for the manufacture of foundry molds and cores, the specified ingredients are loaded in a certain sequence and mixed at a temperature of 35-40 ° C for 1-1.5 hours into a reactor equipped with a heating jacket, a condenser and a mixing device. After this, the manufactured binder is poured into a container.

The emulsion foundry binder of the claimed composition is a homogeneous, viscous mass at ambient temperature from light yellow to dark brown. The product is stable during storage and does not separate into its phases for a long time. In the emulsion binder of the claimed composition contains 45-55% of the active (binder) substance. The nominal viscosity of the product depends on the method of preparation and is in the range of 45-140 s with a VZ-4 viscometer.

The effectiveness of the proposed binder was tested in a generally accepted way, namely, quartz sand in runners was mixed with a certain amount of binder, the product was molded, dried for 1 h at a temperature of 230-250 ° C and strength characteristics were determined.

Example 1. In a reactor equipped with a jacket for heating, a reflux condenser and a mixing device, put 50 weight. including a 50% solution of lignosulfonates in water, 10 parts by weight nonionic surfactant with 10 units of ethylene oxide (OP-10) and 20 parts by weight water. The mixture is thoroughly mixed until it is completely homogenized, and 35 parts by weight are added thereto with constant stirring in portions. tall flask heated to a temperature of 70 ° C and then an additional 10 parts by weight water. The mass is stirred at ambient temperature until complete homogenization and drained.

The resulting emulsion binder is a direct-type stable emulsion with a viscosity of 69 s (according to VZ-4) at ambient temperature.

2 parts by weight quartz sand was placed in runners, 0.12 parts by weight were loaded there. emulsion binder (2.6% of active (binders) substances). After 5-7 minutes of mixing, molds (in the form of “eights”) were made on the molds and dried for 1 h at a temperature of 230–250 ° С. The measured dry strength was 10 kgf / cm ² (average of 5 measurements).

Example 2. The same as in example 1, but for the manufacture of molds in the sand was introduced 0.22 wt.h. emulsion binder (3.8% of active ingredients).

Example 3. The same as in example 1. But as a nonionic surfactant, a product with 7 units of ethylene oxide (OP-7) was used, and 0.27 parts by weight were introduced into the runners. emulsion binder (4.5% of active ingredients).

Example 4. In the reactor of example 1 was placed 30 parts by weight tall pitch and 20 parts by weight organic solvent - nefras (illuminating kerosene) and 10 parts by weight nonionic surfactant with 2 units of ethylene oxide (OTM-2). The mixture was heated to a temperature of 70-80 ° C and stirred until a homogeneous mass. There, in portions, with constant stirring, a pre-prepared mixture containing 50 parts by weight was dosed. 50% aqueous solution of lignosulfonates and 10 parts by weight water. Stirring was carried out until the mixture was completely homogenized.

The resulting emulsion binder is a stable inverse emulsion with a viscosity of 130 s (according to VZ-4) at ambient temperature. The manufacture and testing of the molds was carried out as in Example 1. The strength of the molds in the dry state was 20 kgf / cm ² .

Example 5. The same as in example 4. But as a nonionic surfactant used a product with 4 units of ethylene oxide (OP-4) in an amount of 13 parts by weight

All results of the preparation and testing of emulsion binder are summarized in the table.

The above data indicate that the proposed binder provides the required strength of the molding sand in both wet and dry conditions. A significant advantage of the proposed emulsion binder over the prototype is the homogeneity of the product, its stability and the almost complete absence of adhesion of the moldable mixture to the tooling.

The proposed foundry binder provides within the claimed limits the receipt of the product of the required quality, and its use is the achievement of the necessary strength characteristics of the rods. The decrease in the proportion of tall pitch and lignosulfonates leads to the need to increase the consumption of a binder and adversely affects the stability of the product. In the case of a decrease in the proportion of nonionic surfactant in the binder, it is not possible to obtain a stable, immiscible product. Increasing the proportion of components in the composition is undesirable due to economic considerations.

The manufacture of the inventive foundry emulsion binder does not require the use of special technological equipment, which allowed its industrial production in the conditions of the State Unitary Enterprise “Neivo-Rudyansky Timber Chemical Plant” (town of Neivo-Rudyanka, Sverdlovsk Region).

The use of the inventive binder for the manufacture of rods also does not require special equipment, fully fits into the operating equipment of foundries, which is confirmed by the results of its use in the conditions of OAO Nizhny Tagil Boiler and Radiator Plant (Sverdlovsk Region). An important advantage of the claimed emulsion binder is that when it is used in enterprises, no additional components are required and the product is ready for use.

Claims (1)

Thermal curing emulsion binder for the manufacture of foundry cores and molds, including water-soluble lignosulfonates, an organic solvent and tall pitch, characterized in that it additionally contains a nonionic surfactant (surfactant), which is a product of the hydroxyethylation of organic alcohols, acids or mixtures thereof with an amount oxyethyl units 2-10 in the following ratio of ingredients, wt.%: Tall pitch 25-28 Hydrocarbon solvent 0-17 Lignosulfonates in terms of dry matter 20-21 Nonionic surfactant 8-10.5 Water Else