CN104858355A - Precoated sand with excellent breathability and heat resistance for hot method and preparation method thereof - Google Patents

Abstract

The invention discloses precoated sand with excellent breathability and heat resistance for a hot method. The precoated sand is characterized by being prepared by the following raw materials in parts by weight: 4-6 parts of thermoplastic phenolic resins, 0.7-0.9 part of urotropin, 2.1-3 parts of water, 70-80 parts of quartz sand, 13-18 parts of bauxite, 2-4 parts of high-temperature cement, 10-14 parts of pottery clay, 2-4 parts of aluminum chloride, 1.5-2.5 parts of silica gel, 3.5-5 parts of triethyl citrate, 0.25-0.3 part of calcium stearate, and 5-7 parts of synergist. As the synergist prepared by a special process is added, the fluidity, the breathability, the cooling performance and the strength of the precoated sand are enhanced, and the precoated sand is compact in surface, and is not liable to be cracked and deformed; the bauxite, the high-temperature cement and the pottery clay are added in the formula to mix with the quartz sand, so that the fire resistance and the breathability are improved; such components as aluminum chloride and silica gel are added to fit the urotropin, so that the product curing speed and hardness are improved; and the prepared precoated sand is excellent in breathability and heat resistance, and is worthy of promoting.

Description

A kind of ventilative heat-resisting all excellent hot method precoated sand and preparation method thereof

Technical field

The present invention relates to molding sand technical field, particularly a kind of ventilative heat-resisting all excellent hot method precoated sand 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.It is poor that precoated sand of the prior art also exists heat resistance, and poor fluidity or molding sand exhaust freely do not cause foundry goods to there is the phenomenon such as pore, surface porosity etc.

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 Graphene of rapid heat dissipation, is increased the compositions such as the dibutyl phthalate of mobility, is 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 bauxite, high-temperature cement, potter's clay etc. and coordinates quartz sand to make mixed sand in formula, improve fire resistance and gas permeability, add the components matching such as aluminium chloride, silica gel methenamine, improve curing rate and the hardness of product, the precoated sand gas permeability made and heat resistance are all excellent, and technique is simply convenient to control, cost is low, production efficiency is high, particularly produces complex precise foundry goods, is widely used in manufacturing sand mold and the core of complicated, thin-walled.

Summary of the invention

The object of this invention is to provide a kind of ventilative heat-resisting all excellent hot method precoated sand and preparation method thereof.

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

A ventilative heat-resisting all excellent hot method precoated sand, is made up of the raw material of following weight portion: novolac resin 4-6, methenamine 0.7-0.9, water 2.1-3, quartz sand 70-80, bauxite 13-18, high-temperature cement 2-4, potter's clay 10-14, aluminium chloride 2-4, silica gel 1.5-2.5, triethyl citrate 3.5-5, calcium stearate 0.25-0.3, 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.

A kind of ventilative heat-resisting all excellent hot method precoated sand of the present invention, be made up of following concrete steps:

(1) quartz sand, bauxite, potter's clay 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 silica gel, triethyl citrate and 0.6 times amount while mixed grind, continuation mixed grind 70-80 adds the novolac resin of surplus again after second;

(3) by formation solution soluble in water for methenamine, then slowly join 70% of solution in puddle mixer, after continuing hot lower mixed grind 75-85 second, then add the solution 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 30-35 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's interpolation makes synergist by special process, and enhance the mobility of precoated sand, gas permeability, thermal diffusivity and intensity, surface compact is craze and transfiguration not easily; In formula, add bauxite, high-temperature cement, potter's clay etc. mix with quartz sand, improve fire resistance and gas permeability, add the components matching such as aluminium chloride, silica gel methenamine, improve curing rate and the hardness of product, the precoated sand gas permeability made and heat resistance are all excellent, and technique is simply convenient to control, cost is low, is widely used in manufacturing sand mold and the core of complicated, thin-walled.

Detailed description of the invention

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

A ventilative heat-resisting all excellent hot method precoated sand, is made up of the raw material of following weight portion (kilogram): novolac resin 4, methenamine 0.7, water 2.1, quartz sand 70, bauxite 13, high-temperature cement 2, potter's clay 10, aluminium chloride 2, silica gel 1.5, triethyl citrate 3.5, calcium stearate 0.25, 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.

A kind of ventilative heat-resisting all excellent hot method precoated sand of the present invention, be made up of following concrete steps:

(1) quartz sand, bauxite, potter's clay 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 silica gel, triethyl citrate and 0.6 times amount, continue mixed grind adds surplus again novolac resin after 75 seconds;

(3) by formation solution soluble in water for methenamine, then slowly join 70% of solution in puddle mixer, continue hot lower mixed grind after 80 seconds, then add the solution of surplus, continue mixed grind 15 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 30 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 for being greater than 2.3MPa, and burning decrement 3.1%, fusing point is 99 DEG C.

Claims (2)

1. a ventilative heat-resisting all excellent hot method precoated sand, it is characterized in that, be made up of the raw material of following weight portion: novolac resin 4-6, methenamine 0.7-0.9, water 2.1-3, quartz sand 70-80, bauxite 13-18, high-temperature cement 2-4, potter's clay 10-14, aluminium chloride 2-4, silica gel 1.5-2.5, triethyl citrate 3.5-5, calcium stearate 0.25-0.3, 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. a kind of ventilative heat-resisting all excellent hot method precoated sand according to claim 1, is characterized in that, be made up of following concrete steps:

(1) quartz sand, bauxite, potter's clay 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 silica gel, triethyl citrate and 0.6 times amount while mixed grind, continuation mixed grind 70-80 adds the novolac resin of surplus again after second;

(3) by formation solution soluble in water for methenamine, then slowly join 70% of solution in puddle mixer, after continuing hot lower mixed grind 75-85 second, then add the solution 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 30-35 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.