CN105414455A - High-thermal-stability modified alkaline phenolic resin self-hardening sand for pump valve casting and preparation method of high-thermal-stability modified alkaline phenolic resin self-hardening sand - Google Patents

Abstract

The invention discloses high-thermal-stability modified alkaline phenolic resin self-hardening sand for a pump valve casting. A modified phenolic resin adhesive used in the resin sand has advantages of low viscosity, high bonding strength, good plasticity, low brittleness, lower contents of free phenol and free formaldehyde, smaller using amount, low hardening speed and the like; using performance and reusing performance of molding sand can be improved effectively; mixed nano magnesium oxide porous polypropylene fibers can form complicated and continuous net-shaped structures among sand materials, so that the sand materials can be molded more easily, the strength of a model is higher, meanwhile, thermoplasticity time is longer, stress generated by heating of the sand materials is relieved, the retention time of sand molds is prolonged, breathability is improved, and scattering and peeling are easier after pouring is finished; and by spodumene added in the sand materials, thermal stability of the sand molds can be improved effectively, the phenomenon that the sand molds crack and scatter too early in a pouring process is prevented, and the purpose of improving the quality of the casting is achieved.

Description

Modified alkaline phenolic resins self-hardening sand of a kind of pump valve foundry goods high heat stability and preparation method thereof

Technical field

The present invention relates to resin sand technical field, particularly relate to modified alkaline phenolic resins self-hardening sand of a kind of pump valve foundry goods high heat stability and preparation method thereof.

Background technology

Pump, valve foundry goods have the features such as wall is thin, complex-shaped, and particularly strict to the quality requirement of molding sand in casting process, the quality of molding sand is also the key factor being related to casting quality.Molding sand is mainly used for the material of moulding in casting according to the class that different ratios is mixed by sand material, bonding agent and adminicle etc., different according to the bonding agent used, clay-bonded sand, water-glass sand, resin sand etc. can be divided into, wherein phenol resin sand is widely used in domestic casting industry, wherein air-set mold phenol resin sand because its mulling is convenient, to prepare the advantage such as simple, rate of dispersion is fast, bonding force is strong more in sector application.

Although air-set mold phenol resin sand possesses the advantage of its uniqueness; but also there are some shortcomings of comparatively giving prominence in it; be mainly manifested in that viscosity is large, fragility is large, gas forming amount is high, foundry goods easily produces pin hole, cost is higher, the not easily aspect such as recycling; along with pump valve foundry goods is to the future development of production scale and high precision int, development efficient pollution-free, cost phenolic resin binder that is low, high comprehensive performance are the important prerequisites of casting high quality casting.

Summary of the invention

The object of the invention is exactly the defect in order to make up prior art, provides modified alkaline phenolic resins self-hardening sand of a kind of pump valve foundry goods high heat stability and preparation method thereof.

The present invention is achieved by the following technical solutions:

A modified alkaline phenolic resins self-hardening sand for pump valve foundry goods high heat stability, this resin sand is prepared by the raw material of following weight portion: forsterite sand 25-30, spodumene 5-8, old sand 60-80, iron oxide 1-2, nano magnesia 0.5-0.6, polypropylene chip 0.4-0.5, calcium carbonate 0.01-0.02, phenol-formaldehyde resin modified bonding agent 1.2-1.5, curing agent 0.3-0.4.

Described phenol-formaldehyde resin modified bonding agent is made up of the raw material of following weight portion: potassium hydroxide solution 3-5, urea 1-2, silane coupler 0.1-0.2 that the formalin 20-35 that octyl epoxy stearate 0.2-0.3, organic silicon surfactant 0.1-0.2, nano aluminium oxide 1-2, Triafol T 2-3, phenol 20-25, concentration are 35-38%, concentration are 30%, its preparation method is: by phenol, formaldehyde adds in reactor, be heated to 60-80 DEG C, potassium hydroxide solution is added after being uniformly mixed 20-30min, be warming up to 80-100 DEG C of reaction 4-5h, add Triafol T subsequently, urea, organic silicon surfactant, continue to be uniformly mixed 1.5-2h, room temperature is cooled to after reaction terminates, subsequently reactant liquor is carried out decompression distillation dehydration with the ramp of 8-10 DEG C/min under 0.5-0.6 × 105Pa condition, decompression distillation is stopped when temperature reaches 105-110 DEG C, add other leftover materials subsequently, be cooled to room temperature after being uniformly mixed and get final product.

Described curing agent is organosilane ester curing agent.

The preparation method of the modified alkaline phenolic resins self-hardening sand of described a kind of pump valve foundry goods high heat stability is:

(1) first nano magnesia, calcium carbonate, polypropylene chip are uniformly mixed rear melt spinning, making length is 50-80 μm, and diameter is that the porous short fiber of 10-20 μm is for subsequent use;

(2) 60-100 mesh sieve was pulverized after old sand, forsterite sand, spodumene being mixed, screened sand material drops in puddle mixer, add step (1) gained material and other leftover materials except curing agent and bonding agent subsequently again, curing agent is added after mixed at high speed is even, be uniformly mixed 4-5min, then add phenol-formaldehyde resin modified bonding agent, shake out after continuing to be uniformly mixed 8-10min and get final product.

The phenol-formaldehyde resin modified self-hardening sand that the present invention prepares possesses following advantage:

(1) the phenol-formaldehyde resin modified bonding agent prepared has low viscosity, high bonding strength, plasticity is good, fragility is low, free-phenol and the advantage such as free formaldehyde content is lower, consumption is less, setting rate slows down, and effectively can improve molding sand and uses and re-use performance.

(2) porous polypropylene fibre that prepared by nano magnesia blending can form complicated continuous print network structure between sand material, make sand material more easy-formation, mold strength is higher, there is the longer thermoplasticity time simultaneously, alleviate sand material by thermogenetic stress, extend the retention time of sand mold, improve gas permeability, pour into a mould more easily defeated and dispersed after terminating peeling off.

(3) spodumene added in sand material effectively can improve the heat endurance of sand mold, prevents sand mold in casting process from occurring crackle and defeated and dispersed too early reaching the object improving casting quality.

Detailed description of the invention

This embodiment resin sand is prepared by the raw material of following weight portion: forsterite sand 25, spodumene 5, old sand 60, iron oxide 1, nano magnesia 0.5, polypropylene chip 0.4, calcium carbonate 0.01, phenol-formaldehyde resin modified bonding agent 1.2, curing agent 0.3.

Wherein phenol-formaldehyde resin modified bonding agent is made up of the raw material of following weight portion: potassium hydroxide solution 3, urea 1, silane coupler 0.1 that the formalin 20 that octyl epoxy stearate 0.2, organic silicon surfactant 0.1, nano aluminium oxide 1, Triafol T 2, phenol 20, concentration are 35%, concentration are 30%; Its preparation method is: add in reactor by phenol, formaldehyde, be heated to 60 DEG C, potassium hydroxide solution is added after being uniformly mixed 20min, be warming up to 80 DEG C of reaction 4h, add Triafol T, urea, organic silicon surfactant subsequently, continue to be uniformly mixed 1.5h, room temperature is cooled to after reaction terminates, subsequently reactant liquor is carried out decompression distillation dehydration with the ramp of 8 DEG C/min under 0.5 × 105Pa condition, decompression distillation is stopped when temperature reaches 105 DEG C, add other leftover materials subsequently, be cooled to room temperature after being uniformly mixed and get final product.

The curing agent adopted is glycerol triacetate.

The preparation method of this embodiment resin sand is:

(1) first nano magnesia, calcium carbonate, polypropylene chip are uniformly mixed rear melt spinning, making length is 50 μm, and diameter is that the porous short fiber of 10 μm is for subsequent use;

(2) 60 mesh sieves were pulverized after old sand, forsterite sand, spodumene being mixed, screened sand material drops in puddle mixer, add step (1) gained material and other leftover materials except curing agent and bonding agent subsequently again, curing agent is added after mixed at high speed is even, be uniformly mixed 4min, then add phenol-formaldehyde resin modified bonding agent, shake out after continuing to be uniformly mixed 8min and get final product.

The bonding strength of the phenol-formaldehyde resin modified bonding agent obtained by the present embodiment is 6.50MPa, free phenol content≤0.5%, content of free aldehyde≤0.1%, maximum decomposition temperature can reach 540 DEG C, this resin sand stripping time >=25min, 24h tensile strength is 1.52MPa, and core hydroscopicity is low, and gas forming amount reduces by 40% than traditional phenolic resins molding sand, the surface quality of continuous castings obtained is high, size is accurate, and yield rate can reach more than 95%, and reclamation of return sand rate can reach 85%.

Claims (4)

1. the modified alkaline phenolic resins self-hardening sand of a pump valve foundry goods high heat stability, it is characterized in that, this resin sand is prepared by the raw material of following weight portion: forsterite sand 25-30, spodumene 5-8, old sand 60-80, iron oxide 1-2, nano magnesia 0.5-0.6, polypropylene chip 0.4-0.5, calcium carbonate 0.01-0.02, phenol-formaldehyde resin modified bonding agent 1.2-1.5, curing agent 0.3-0.4.

2. the modified alkaline phenolic resins self-hardening sand of a kind of pump valve foundry goods high heat stability as claimed in claim 1, it is characterized in that, described phenol-formaldehyde resin modified bonding agent is made up of the raw material of following weight portion: potassium hydroxide solution 3-5, urea 1-2, silane coupler 0.1-0.2 that the formalin 20-35 that octyl epoxy stearate 0.2-0.3, organic silicon surfactant 0.1-0.2, nano aluminium oxide 1-2, Triafol T 2-3, phenol 20-25, concentration are 35-38%, concentration are 30%, its preparation method is: by phenol, formaldehyde adds in reactor, be heated to 60-80 DEG C, potassium hydroxide solution is added after being uniformly mixed 20-30min, be warming up to 80-100 DEG C of reaction 4-5h, add Triafol T subsequently, urea, organic silicon surfactant, continue to be uniformly mixed 1.5-2h, room temperature is cooled to after reaction terminates, subsequently reactant liquor is carried out decompression distillation dehydration with the ramp of 8-10 DEG C/min under 0.5-0.6 × 105Pa condition, decompression distillation is stopped when temperature reaches 105-110 DEG C, add other leftover materials subsequently, be cooled to room temperature after being uniformly mixed and get final product.

3. the modified alkaline phenolic resins self-hardening sand of a kind of pump valve foundry goods high heat stability as claimed in claim 1, it is characterized in that, described curing agent is organosilane ester curing agent.

4. the preparation method of the modified alkaline phenolic resins self-hardening sand of a kind of pump valve foundry goods high heat stability as claimed in claim 1, it is characterized in that, described preparation method is:

(1) first nano magnesia, calcium carbonate, polypropylene chip are uniformly mixed rear melt spinning, making length is 50-80 μm, and diameter is that the porous short fiber of 10-20 μm is for subsequent use;

(2) 60-100 mesh sieve was pulverized after old sand, forsterite sand, spodumene being mixed, screened sand material drops in puddle mixer, add step (1) gained material and other leftover materials except curing agent and bonding agent subsequently again, curing agent is added after mixed at high speed is even, be uniformly mixed 4-5min, then add phenol-formaldehyde resin modified bonding agent, shake out after continuing to be uniformly mixed 8-10min and get final product.