CN104858357A - Precoated sand with high-temperature resistance and good compactness and preparation method thereof - Google Patents

Abstract

The invention discloses precoated sand with high-temperature resistance and good compactness. The precoated sand is characterized by being prepared by the following raw materials in parts by weight: 75-86 parts of quartz sand, 7-9 parts of fire clay, 10-12 parts of yellow sand, 4-6 parts of thermoplastic phenolic resins, 0.8-1 part of urotropin, 1-1.5 parts of boric acid, 0.2-0.3 part of iron oxide red, 0.2-0.3 part of calcium stearate, 2.5-3 parts of water, 1-2 parts of polyurethane adhesive, and 5-7 parts of synergist. The precoated sand is prepared by a hot method; the social need is satisfied through modifying a formula; the synergist prepared by a special process is added; the fluidity, the air permeability, the cooling capacity and the strength of the precoated sand are enhanced; the precoated sand is compact in surface, and is not liable to be cracked and deformed; such components as boric acid and fire clay for raising the heat resisting temperature and polyurethane adhesive for improving the sand adhesiveness are additionally added; and the prepared precoated sand has the advantages of high-temperature resistance, good compactness, difficult sand bonding, low cost, good quality and high production efficiency.

Description

Precoated sand that a kind of high temperature resistant compactness is good and preparation method thereof

Technical field

The present invention relates to molding sand technical field, precoated sand that particularly a kind of high temperature resistant compactness is good and preparation method thereof.

Background technology

Precoated sand is covered with molding sand or the core sand of one deck hard resin film on sand grain surface before referring to moulding.Widely used is in recent years the production technology of hot method precoated sand, namely sand is preheating to uniform temperature, adds resin and make its melting, stirs and makes resin-coating at sand grain surface, add the methenamine aqueous solution and lubricant, cooling, broken, sieve to obtain precoated sand.Because precoated sand has that intensity is high, gas forming amount is low, production casting dimension accuracy is high, any surface finish, is convenient to the advantages such as preservation, apply increasingly extensive in recent years.Precoated sand of the prior art also exists that heat resistance is poor, roughness is comparatively large, the defect of easily scab on foundry goods and problem.

Existing much about the invention of modification precoated sand, but the present invention is by research, add a kind of synergist and modification is carried out to common precoated sand, this synergist includes ventilative good maize straw, potter's clay, the compositions such as the Graphene of rapid heat dissipation, made by special process, enhance the mobility of precoated sand, gas permeability, thermal diffusivity and intensity, surface compact is craze and transfiguration not easily.The present invention also added boric acid, seat clay etc. and improves the composition of heat resisting temperature in formula, and adhesive for polyurethane etc. improves the caking property of sand grains, and the precoated sand made is high temperature resistant, compactness good, not easily scab.

Summary of the invention

The object of this invention is to provide good precoated sand of a kind of high temperature resistant compactness and preparation method thereof.

In order to realize object of the present invention, the present invention is by following scheme implementation:

The precoated sand that high temperature resistant compactness is good, is made up of the raw material of following weight portion: quartz sand 75-86, seat clay 7-9, yellow sand 10-12, novolac resin 4-6, methenamine 0.8-1, boric acid 1-1.5, iron oxide red 0.2-0.3, calcium stearate 0.2-0.3, water 2.5-3, adhesive for polyurethane 1-2, synergist 5-7;

Described synergist is prepared from by the raw material of following weight portion: maize straw 4-6, starch 2-3, waterglass 3-5, calcium hydroxide 1.5-2.5, magnesium chloride 1-2, Graphene 4-5, potter's clay 20-25, zirconium English powder 9-11, dibutyl phthalate 3-4, water 9-12; Preparation method is as follows: maize straw crushed after being dried is become 80-100 object powder and potter's clay, starch mixing and stirring, add water to stir, temperature control is at 60 DEG C-80 DEG C, keep 1-1.5 hour, then add all the other residual components except waterglass, dibutyl phthalate, mixing 20-30 minute, add waterglass, dibutyl phthalate again, put into puddle mixer wet mixing 20-30 second, post-drying of shaking out, final powder is broken into 200-250 order and get final product.

The precoated sand that a kind of high temperature resistant compactness of the present invention is good, be made up of following concrete steps:

(1) quartz sand, seat clay, yellow sand are put into pulverizer and pulverized, cross 200-300 mesh sieve and form mixed sand, then fluidized bed furnace is heated to 160 DEG C, starts fluidized bed furnace inner blower, slowly add mixed sand, by the heating temperatures of mixed sand to 140 DEG C-150 DEG C;

(2) be put in puddle mixer by the mixed sand after heating, keep 160 DEG C of constant temperature, add the novolac resin of adhesive for polyurethane and 0.6 times amount while mixed grind, continuation mixed grind 70-80 adds the novolac resin of surplus again after second;

(3) by methenamine, boric acid formation mixed liquor soluble in water, then slowly join 70% of mixed liquor in puddle mixer, after continuing hot lower mixed grind 75-85 second, then add the mixed liquor of surplus, continue mixed grind 10-20 second;

(4) close puddle mixer heating tube, be blown into cold front heavy rain mixed sand, when being cooled to about 100 DEG C, add all the other residual components equably, mix 20-30 second, then shake out in disintegrating machine, air-cooled to fragmentation when 40 DEG C-60 DEG C, be screened in cooler, air-cooled to less than 35 DEG C, pack of shaking out is for subsequent use.

Excellent effect of the present invention is: the present invention adopts hot legal system for precoated sand, by meeting society need to the modification of formula, add the synergist that special process is made, enhance the mobility of precoated sand, gas permeability, thermal diffusivity and intensity, surface compact is craze and transfiguration not easily; Also added boric acid, seat clay etc. and improve the composition of heat resisting temperature, and adhesive for polyurethane etc. improves the caking property of sand grains, the precoated sand made is high temperature resistant, compactness good, not easily scab, and cost is low, and quality is good, and production efficiency is high.

Detailed description of the invention

Below by instantiation, the present invention is described in detail.

The precoated sand that high temperature resistant compactness is good, is made up of the raw material of following weight portion (kilogram): quartz sand 75, seat clay 7, yellow sand 10, novolac resin 4, methenamine 0.8, boric acid 1, iron oxide red 0.2, calcium stearate 0.2, water 2.5, adhesive for polyurethane 1, synergist 5;

Described synergist is prepared from by the raw material of following weight portion (kilogram): maize straw 4, starch 2, waterglass 3, calcium hydroxide 1.5, magnesium chloride 1, Graphene 4, potter's clay 20, zirconium English powder 9, dibutyl phthalate 3, water 9; Preparation method is as follows: maize straw crushed after being dried is become 100 object powder and potter's clay, starch mixing and stirring, add water to stir, temperature control is at 60 DEG C-80 DEG C, keep 1 hour, then add all the other residual components except waterglass, dibutyl phthalate, mix 20 minutes, add waterglass, dibutyl phthalate again, put into puddle mixer wet mixing 20 seconds, post-drying of shaking out, final powder is broken into 200 orders and get final product.

The precoated sand that a kind of high temperature resistant compactness of the present invention is good, be made up of following concrete steps:

(1) quartz sand, seat clay, yellow sand are put into pulverizer and pulverized, cross 200 mesh sieves and form mixed sand, then fluidized bed furnace is heated to 160 DEG C, starts fluidized bed furnace inner blower, slowly add mixed sand, by the heating temperatures of mixed sand to 140 DEG C-150 DEG C;

(2) mixed sand after heating is put in puddle mixer, keeps 160 DEG C of constant temperature, while mixed grind, add the novolac resin of adhesive for polyurethane and 0.6 times amount, continue mixed grind adds surplus again novolac resin after 75 seconds;

(3) by methenamine, boric acid formation mixed liquor soluble in water, then slowly join 70% of mixed liquor in puddle mixer, continue hot lower mixed grind after 80 seconds, then add the mixed liquor of surplus, continue mixed grind 10 seconds;

(4) close puddle mixer heating tube, be blown into cold front heavy rain mixed sand, when being cooled to about 100 DEG C, add all the other residual components equably, mixed 20 seconds, then shake out in disintegrating machine, air-cooled to fragmentation when 40 DEG C-60 DEG C, be screened in cooler, air-cooled to less than 35 DEG C, pack of shaking out is for subsequent use.

The performance test of the present embodiment precoated sand is as follows: normal temperature bending strength is 6.5MPa, and hot bending strength is 2.6MPa, burning decrement 3.2%, and fusing point is 102 DEG C.

Claims (2)

1. the precoated sand that a high temperature resistant compactness is good, it is characterized in that, be made up of the raw material of following weight portion: quartz sand 75-86, seat clay 7-9, yellow sand 10-12, novolac resin 4-6, methenamine 0.8-1, boric acid 1-1.5, iron oxide red 0.2-0.3, calcium stearate 0.2-0.3, water 2.5-3, adhesive for polyurethane 1-2, synergist 5-7;

Described synergist is prepared from by the raw material of following weight portion: maize straw 4-6, starch 2-3, waterglass 3-5, calcium hydroxide 1.5-2.5, magnesium chloride 1-2, Graphene 4-5, potter's clay 20-25, zirconium English powder 9-11, dibutyl phthalate 3-4, water 9-12; Preparation method is as follows: maize straw crushed after being dried is become 80-100 object powder and potter's clay, starch mixing and stirring, add water to stir, temperature control is at 60 DEG C-80 DEG C, keep 1-1.5 hour, then add all the other residual components except waterglass, dibutyl phthalate, mixing 20-30 minute, add waterglass, dibutyl phthalate again, put into puddle mixer wet mixing 20-30 second, post-drying of shaking out, final powder is broken into 200-250 order and get final product.

2. the precoated sand that a kind of high temperature resistant compactness is good according to claim 1, is characterized in that, is made up of following concrete steps:

(1) quartz sand, seat clay, yellow sand are put into pulverizer and pulverized, cross 200-300 mesh sieve and form mixed sand, then fluidized bed furnace is heated to 160 DEG C, starts fluidized bed furnace inner blower, slowly add mixed sand, by the heating temperatures of mixed sand to 140 DEG C-150 DEG C;

(2) be put in puddle mixer by the mixed sand after heating, keep 160 DEG C of constant temperature, add the novolac resin of adhesive for polyurethane and 0.6 times amount while mixed grind, continuation mixed grind 70-80 adds the novolac resin of surplus again after second;

(3) by methenamine, boric acid formation mixed liquor soluble in water, then slowly join 70% of mixed liquor in puddle mixer, after continuing hot lower mixed grind 75-85 second, then add the mixed liquor of surplus, continue mixed grind 10-20 second;

(4) close puddle mixer heating tube, be blown into cold front heavy rain mixed sand, when being cooled to about 100 DEG C, add all the other residual components equably, mix 20-30 second, then shake out in disintegrating machine, air-cooled to fragmentation when 40 DEG C-60 DEG C, be screened in cooler, air-cooled to less than 35 DEG C, pack of shaking out is for subsequent use.