SU1581465A1 - Antistick coating for moulds and cores - Google Patents

Abstract

The invention relates to foundry and can be used as a nonstick coating for casting molds and cores. The purpose of the invention is to increase the strength of the coating and its coating ability, reduce the duration of its hardening and decrease hygroscopicity, which is achieved by using a cationic polymer selected from a number of epaflocks in the coating composition. Nonstick coating contains, wt%: technical lignosulfonates 1.5-2.6

bentonite 0.9-2.5

alkali (in terms of dry substance) 0,25-0,42

anionic surfactant 0.3-0.55, a cationic polymer of a number of epaflocks mol.m. 5 .10 3-15 .10 3 2-5, water 39-49, refractory filler based on distensillimanite the rest. At the same time, epaflok has the following chemical composition, wt%: polyethylene polyamine and epichlorohydrin-based polymer 23-28, hydrogen chloride 3-5, sulfuric acid 4.0-4.5

water the rest. Epaflok-2 has the following chemical composition, wt.%: A polymer based on polyethylene amine, epichlorohydrin and dichlorohydrin or polyethylene glycol di-oxide mol.m. 200-600 23-28, hydrogen chloride 3-5, water the rest. The introduction of epaflocks into the composition of the coating helps in removing water to form a strong film on the filler grains, due to which its strength increases, the hygroscopicity decreases, and the covering power improves. 2 hp ff, 2 tab.

Description

The invention relates to foundry and can be used as a nonstick coating for casting molds and cores.

The purpose of the invention is to increase the strength of the coating and its coating power, reducing the duration

its hardening and reduction of hygroscopicity

The coating contains lignosulfonate binder, bentonite, alkali, anionic surfactant, water, cationic polymer from the row

epaflokov with a mole. 5 103-151 O3 and refractory filler.

As lignosulfonate binder used technical lignosulfonates (OST 13-18.3-83), sulfite yeast mash (MRTU 13-04-66, OST 81-79-74), sulfite bard (GOST 6632-53, GOST 8518-57) and sulphite liquor with a density of 1.24-1.27 g / cm.

Sodium hydroxide and potassium hydroxide were used as alkali (GOST 2263-79). Alkalis are added to eliminate rapid chemical interaction with epaflocks and neutralize the free acids of the polymer.

As a refractory filler, powdered kyanene-schliemanite concentrate (TU 48-4-307-74) was used.

Bentonite is an additional binding material that is used according to GOST 3226-77.

As an anionic surfactant, Progress synthetic detergent, DS-RAS and CNPD were used.

The addition of surfactants creates interfacial particles (for example, a copolymer, consisting of an epifloc and lignosulfonates, which acts as a binding and a consistency additive) of the nonstick paint electrical double layer, as a result of which the aggregate stability increases, the viscosity of the medium increases. and the covering power is increased. Due to this, it is also possible to reduce the content of the consistency binder complex additive.

Epaflocks 1 and 2, which are water-soluble polymers, which are obtained in the form of aqueous 25-30% solutions, by polycondensation of polyethylene-polyamine (NEP) grade A (TU 6-02-594-80) with epichlorohydrin or epichlorohydrin (EPH) and dichlorohydrins or diepoxides of polyethylene glycols with mol.m. 200-600. The process is carried out in two stages with obtaining in both cases in the first stage as a result of the interaction of PEPA with the EPC of an aqueous solution of a prepolymer with a viscosity of 20-80 cP at 200 ° C. poly0 aqueous solution

five

0

five

0

five

0

five

0

five

measure with a viscosity of 2-8 Pz at 20CC, which is stabilized by the introduction of sulfuric acid to a pH of 4-5 (the product form has the name epaflok-1).

When the prepolymer solution is bound with a small amount of dichloro-gidrin or polyethylene glycol dioxide, mol.m. 200-600 receive an aqueous solution of the polymer, which does not require stabilization with acid and has the name epaflok-2 (TU 6-02- 2-865-85). Mol.m. both polymers are in the range of 5-15 thousand. Their structure is formed by primary, secondary, and tertiary amino groups linked to the first polymer by ethylene and 2-hydroxypropylene units. Thus, the polymer has

groups:

i -NH2, NH, -N, -CH2-CH2 -, - CHz-CH-CHtCH

and in the second polymer, ethylene, 2-hydroxypropylene, and polyoxyethylene, ie, more links are added (-O-CH -CH-O-). At the same time, part of the amine groups is neutralized with hydrogen chloride, which is liberated as a result of the polycondensation reaction. Due to the presence of free amine groups, polymer solutions have a basic character and a pH of 9-120 I

Epaflocks are used to clarify slurry waters of coal preparation plants for papermaking, for wastewater treatment, etc. The epaflocks have binding properties, which, in the nonstick coating, act as high polymers, forming a strong film when moisture is removed. With alkaline lignosulfonates, the polymer reacts chemically to form an even stronger film after removing water during drying. The excess polymer that does not react chemically melts and, upon cooling, forms strong films on the refractory filler grains. At the same time, the strength of the nonstick paint increases and the hygroscopicity decreases. The manifestation of chemical activity during the interaction of the polymer with alkaline lignosulfonates and the neutralization of the acids of the polymer, especially sulfuric acid, shortens the time of antiburning paint and improves the covering ability.

The compositions used epaflokov below 0

1. EP Flock-1, wt. / about: polymer with mol, m 5 103-13 10 3; and on the basis of lolythylene polyamine and hydrochlorhydrin 23.0-28.0, hydrogen chloride 3.0-5.0; sulfuric acid 4.0-4.5; water the rest.

2. Epaflok-2, mass%: polymer mol.m. 5-103 15-103 based on poly (ethylene polyamine), epichlorohydrin and dichlorohydrin or polyethylene glycol mol epoxide. 200-600 23.0-28.0; hydrogen chloride 3.0-5.0; water the rest

The preparation of the nonstick coating is carried out as follows.

The calculated amounts of lignosulfonate binder and alkali are alternately dissolved in water and mixed. After that, anionic surfactant and flocculant epafloCo are added to the lignosulfonate alkaline binder composition. The resulting composition is poured into a cracker and mixed for 5-6 minutes. Then a clay binder and a refractory filler are added and mixed for 15-20 minutes. The prepared composition. Is applied to the surface of the forms and rods with a brush, spray gun or dipping

The density of nonstick paint was controlled by a PA type densimeter (GOST 1300-74), viscosity by a VZ-4 viscometer, sedimentation stability and abrasion resistance according to GOST 10772-78. Covering ability was evaluated by the number of filled with nonstick paint cells (1 mm) wire mesh 15 seconds after removing the grid from the liquid paint according to the Formula:

Tooo

TO

where n is the number of empty cells; 1000 is the total number of cells.

The duration of the drying (curing) was taken as the time (in minutes) after the first painting, when the brush stops moving the first layer of paint during re-painting.

Paint hygroscopicity is determined by the equation:

W - U0%,

five

0

0

where P is the sample of the investigated paint, g; P - paint hinge after aging, G o

Prigar was evaluated according to the method of Obolentsev F. F, according to which the laboriousness of its removal is expressed by points.

The compositions of the proposed anti-burn coating are shown in Table 1.

The physicomechanical and technological properties of the coating are presented in table. 2

Data analysis table. 1 and 2 shows that the implementation of the invention increases the strength of the nonstick paint by 1.6-2.8 times, improves the covering power by 3.0-4.5%, reduces the wiring time by 3-5 minutes and reduces the hygroscopicity in 3- 4 times. Due to this, the anti-stick properties of the paint are improved.

Claims (1)

1. Non-stick coating for casting molds and cores, including refractory filler based on distensillimanite, technical lignosulfonates, bentonite, alkali and water, characterized in that, in order to increase the strength of the coating and its coating ability, reduce the duration of its solidification 5 and reduce hygroscopicity , it additionally contains a cation-active polymer from a number of epaflocks with a mol.m. 5 PO -15-U3 and anionnbe surfactant with the following ratio of ingredients, wt.%: Technical lignosulfonates, 5-2.60 Bentonite 0.90-2.50 Alkali (in terms of 5 to substance) 0,25-0,42 Anionic surfactant 0.30-0.55 Cationic polymer from p yes epaflokov mol.m., 5 10 - 1540 2.0-5.0 Voda39,0-49,0 Refractory filler on based dist. Sillimanite Else five 71581465 2, The coating according to claim 1, characterized in that the cationic polymer with a mol. Mo 51103-15 Yu3 has eight the polymer with mole „510e-1510z has the following chemical composition, wt%“: Order 2053 Circulation 628 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology 113035, Moscow, Zh-35, 4/5, Raushsk nab. Subscription