CN114163210B - Self-hardening curing agent and preparation method thereof - Google Patents

Abstract

The invention discloses a self-hardening curing agent and a preparation method thereof, and relates to the field of curing agents, wherein the self-hardening curing agent is obtained by adding acetone serving as a solvent into modified polyurethane, stirring, then adding sodium fluosilicate, adding glycerol triacetate, propylene carbonate, sorbitol and silica sol, mixing and then putting into a high-speed stirrer for stirring, so that the problems of long hardening reaction time of a sand core, insufficient core strength and easiness in influence of external environment are solved; the modified polyurethane reacts with sodium fluosilicate, a fluorine-silicon chain segment is grafted on a molecular chain of the modified polyurethane to form a cross-linked structure with propylene carbonate, the strength of the cured sand core is enhanced, sorbitol plays a role in curing promotion, silica sol is easy to permeate, cracks and surface microcracks of a casting are avoided, silica bonding is formed among molecules, a good bonding effect is achieved, a sulfonic acid curing agent is avoided, and SO release is avoided ₂ And toxic gases are beneficial to environmental protection.

Description

Self-hardening curing agent and preparation method thereof

Technical Field

The invention relates to the field of curing agents, in particular to a self-hardening curing agent and a preparation method thereof.

Background

The casting is a basic part in the equipment manufacturing industry, the requirements of large castings and complex castings are increased along with the development of the equipment manufacturing industry, and the castings are mostly produced by adopting self-hardening sand molding and core making technologies.

At present, water glass or modified water glass is widely used for molding, and CO is mostly used for solidifying sand cores when the water glass or the modified water glass is used for molding ₂ Or self-hardening, and the like, but the core is manufactured by the methods of structural deficiency, the defect is obvious, the hardening reaction time of the sand core is longer, the time cost in production is increased, and when the size of the sand core is overlarge, the whole sand core is not hardened easily due to poor air permeability and influence on the hardening speed of the sand core, so that the strength of the whole sand core is insufficient and the influence of the external environment is larger.

Disclosure of Invention

In order to overcome the technical problems, the invention aims to provide a self-hardening curing agent and a preparation method thereof:

(1) adding acetone serving as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, adding glycerol triacetate, propylene carbonate, sorbitol and silica sol, mixing, and then putting into a high-speed stirrer for stirring to obtain the self-hardening curing agent, so that the problems that the hardening reaction time of the sand core is long, the core strength is not enough, and the sand core is easily influenced by the external environment are solved;

(2) adding aqueous solutions of bisphenol A and dimethylamine and aqueous solution of formaldehyde into a reaction kettle to obtain a catalyst A, adding 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser pipe under the protection of nitrogen, dropwise adding a butyl acetate solution of the catalyst A, carrying out heat preservation reaction, adding benzoyl chloride, cooling and discharging to obtain the modified polyurethane, and solving the problems that the strength of a curing agent is insufficient and the curing agent is easily influenced by the external environment.

The purpose of the invention can be realized by the following technical scheme:

the self-hardening curing agent comprises the following components in parts by weight:

10-20 parts of sodium fluosilicate, 20-30 parts of glycerol triacetate, 10-20 parts of propylene carbonate, 1-5 parts of sorbitol, 1-5 parts of silica sol and 40-60 parts of modified polyurethane;

the self-hardening curing agent is prepared by the following steps:

s1: adding acetone as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 80-90 ℃, and reacting for 2-6 h;

s2: and (4) adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the step S1, mixing, and then putting into a high-speed stirrer for stirring at 550-650r/min for 20-30min to obtain the self-hardening curing agent.

As a further scheme of the invention: the modified polyurethane is prepared by the following steps:

s21: adding an aqueous solution of bisphenol A and dimethylamine and an aqueous solution of formaldehyde into a reaction kettle, heating for 2-4h at 80-90 ℃, cooling, separating out an organic phase, and carrying out vacuum distillation at 90-100 ℃ and 1.33KPa to obtain a catalyst A;

the chemical reaction formula is as follows:

s22: adding the catalyst A into butyl acetate to obtain a butyl acetate solution of the catalyst A;

s23: under the protection of nitrogen, adding 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser, stirring for 10-15min, heating to 70-80 ℃, dropwise adding a butyl acetate solution of a catalyst A, controlling the dropwise adding speed to be 1-2 drops/s, after the dropwise adding is finished within 20-30min, controlling the temperature to be 70-100 ℃, carrying out heat preservation reaction for 4-6h, adding benzoyl chloride with equal mass for three times during the reaction, keeping the reaction for 1-1.5h every time, continuing stirring for 0.5-1h to terminate the reaction, stopping heating and stirring, cooling and discharging to obtain the modified polyurethane.

The chemical reaction formula is as follows:

as a further scheme of the invention: in step S21, the mass fraction of the aqueous solution of dimethylamine is 25%, the mass fraction of the aqueous solution of formaldehyde is 40%, and the usage ratio of the aqueous solution of bisphenol a, dimethylamine and the aqueous solution of formaldehyde is 18.8 g: 72 g: 42.5 g.

As a further scheme of the invention: in the step S22, the dosage ratio of the catalyst A to butyl acetate is 1 g: 10 mL.

As a further scheme of the invention: the dosage ratio of the 1, 4-diisocyanatobutane, the butyl acetate solution of the catalyst A and the benzoyl chloride in the step S23 is 100-110 g: 0.5 g: 3-6 g.

The preparation method of the self-hardening curing agent specifically comprises the following steps:

s61: adding acetone as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 80-90 ℃, and reacting for 2-6 h;

s62: and (4) adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the step S1, mixing, and then putting the mixture into a high-speed stirrer for stirring at a speed of 550-650r/min for 20-30min to obtain the self-hardening curing agent.

The invention has the beneficial effects that:

(1) the invention adds acetone solvent into modified polyurethane, stirs, then adds sodium fluosilicate, adds triacetin, propylene carbonate, sorbitol and silica sol, mixes and puts into high speed stirrer, stirs, gets the self-hardening curing agent, the modified polyurethane reacts with sodium fluosilicate, grafts the fluorine silicon chain segment on the molecular chain of the modified polyurethane, makes the reaction product have the residual modified polyurethane molecule which does not participate in the graft reaction, also has the modified polyurethane molecule which contains graft fluorine silicon chain segment and isocyanate group, when mixing with propylene carbonate, the isocyanate group and propylene carbonate form cross-linking structure, strengthens the intensity of the sand core after curing, the sorbitol plays the role of curing and accelerating, the silica sol is easy to permeate, avoids the casting producing crack and surface micro crack, forms silica bonding between molecules, plays a good role of bonding, and avoids using sulfonic acid curing agent and releasing SO ₂ And the like, which is beneficial to environmental protection;

(2) adding aqueous solutions of bisphenol A and dimethylamine and aqueous solution of formaldehyde into a reaction kettle to obtain a catalyst A, adding 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser under the protection of nitrogen, dropwise adding a butyl acetate solution of the catalyst A, carrying out heat preservation reaction, adding benzoyl chloride, cooling and discharging to obtain the modified polyurethane serving as a polyurethane crosslinking curing agent, wherein the modified polyurethane not only can improve the curing speed, but also can ensure that a sand core has outstanding hardness, has excellent quick drying property, is not easy to decompose at high temperature, has good thermal stability, good wear resistance and good corrosion resistance, and thus the aim of improving the curing speed of the curing agent is fulfilled.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

the embodiment is a self-hardening curing agent, which comprises the following components in parts by weight:

10 parts of sodium fluosilicate, 20 parts of glycerol triacetate, 10 parts of propylene carbonate, 4 parts of sorbitol, 4 parts of silica sol and 40 parts of modified polyurethane;

the self-hardening curing agent is prepared by the following steps:

s1: adding acetone serving as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 80 ℃, and reacting for 2 hours;

s2: adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the mixture obtained in the step S1, mixing, and then putting the mixture into a high-speed stirrer for stirring at 550r/min for 20min to obtain the self-hardening curing agent;

the modified polyurethane is prepared by the following steps:

s21: adding 18.8g of bisphenol A, 72g of dimethylamine aqueous solution and 42.5g of formaldehyde aqueous solution into a reaction kettle, heating for 2 hours at the temperature of 80 ℃, cooling, separating out an organic phase, and carrying out vacuum distillation at the temperature of 90 ℃ and the pressure of 1.33KPa to obtain a catalyst A;

s22: adding 1g of catalyst A into 10mL of butyl acetate to obtain a butyl acetate solution of the catalyst A;

s23: under the protection of nitrogen, adding 100g of 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser, stirring for 10min, heating to 70 ℃, dropwise adding 0.5g of a butyl acetate solution of a catalyst A, controlling the dropwise adding speed to be 2 drops/s, controlling the temperature to be 70 ℃ after the dropwise adding is finished within 30min, keeping the temperature for 4h, adding benzoyl chloride with equal mass for three times during the reaction, adding benzoyl chloride with equal mass for 1h every time, continuously stirring for 0.5h to terminate the reaction, stopping heating and stirring, cooling and discharging to obtain the modified polyurethane.

Example 2:

the embodiment is a self-hardening curing agent, which comprises the following components in parts by weight:

20 parts of sodium fluosilicate, 30 parts of glycerol triacetate, 20 parts of propylene carbonate, 5 parts of sorbitol, 5 parts of silica sol and 60 parts of modified polyurethane;

the self-hardening curing agent is prepared by the following steps:

s1: adding acetone serving as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 90 ℃, and reacting for 6 hours;

s2: adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the mixture obtained in the step S1, mixing, and then putting the mixture into a high-speed stirrer for stirring at a speed of 650r/min for 30min to obtain the self-hardening curing agent;

the modified polyurethane is prepared by the following steps:

s21: adding 18.8g of bisphenol A, 72g of dimethylamine aqueous solution and 42.5g of formaldehyde aqueous solution into a reaction kettle, heating for 2 hours at the temperature of 80 ℃, cooling, separating out an organic phase, and carrying out vacuum distillation at the temperature of 90 ℃ and the pressure of 1.33KPa to obtain a catalyst A;

s22: adding 1g of catalyst A into 10mL of butyl acetate to obtain a butyl acetate solution of the catalyst A;

s23: under the protection of nitrogen, adding 100g of 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser, stirring for 10min, heating to 70 ℃, dropwise adding 0.5g of a butyl acetate solution of a catalyst A, controlling the dropwise adding speed to be 1 drop/s, controlling the temperature to be 70 ℃ after the dropwise adding is finished within 20min, keeping the temperature for 4h, adding benzoyl chloride with equal mass for three times during the reaction, adding benzoyl chloride with the total mass of 6g at an interval of 1h every time, continuing stirring for 0.5h to terminate the reaction, stopping heating and stirring, cooling and discharging to obtain the modified polyurethane.

Example 3:

the embodiment is a self-hardening curing agent, which comprises the following components in parts by weight:

10 parts of sodium fluosilicate, 30 parts of glycerol triacetate, 20 parts of propylene carbonate, 5 parts of sorbitol, 5 parts of silica sol and 60 parts of modified polyurethane;

the self-hardening curing agent is prepared by the following steps:

s1: adding acetone serving as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 80 ℃, and reacting for 2 hours;

s2: adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the mixture obtained in the step S1, mixing, and then putting the mixture into a high-speed stirrer for stirring at 550r/min for 20min to obtain the self-hardening curing agent;

the modified polyurethane is prepared by the following steps:

s21: adding 18.8g of bisphenol A, 72g of dimethylamine aqueous solution and 42.5g of formaldehyde aqueous solution into a reaction kettle, heating for 4 hours at the temperature of 80 ℃, cooling, separating out an organic phase, and carrying out vacuum distillation at the temperature of 90 ℃ and the pressure of 1.33KPa to obtain a catalyst A;

s22: adding 1g of catalyst A into 10mL of butyl acetate to obtain a butyl acetate solution of the catalyst A;

s23: under the protection of nitrogen, adding 100g of 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser, stirring for 15min, heating to 80 ℃, dropwise adding 0.5g of a butyl acetate solution of a catalyst A, controlling the dropwise adding speed to be 2 drops/s, controlling the temperature to be 100 ℃ after the dropwise adding is finished within 30min, carrying out heat preservation reaction for 4-6h, adding benzoyl chloride with equal mass for three times during the reaction, keeping the interval for 1.5h every time, adding 6g of benzoyl chloride, continuing stirring for 1h to terminate the reaction, stopping heating and stirring, cooling and discharging to obtain the modified polyurethane.

Example 4:

the embodiment is a self-hardening curing agent, which comprises the following components in parts by weight:

20 parts of sodium fluosilicate, 30 parts of glycerol triacetate, 20 parts of propylene carbonate, 5 parts of sorbitol, 5 parts of silica sol and 60 parts of modified polyurethane;

the self-hardening curing agent is prepared by the following steps:

s1: adding acetone serving as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 90 ℃, and reacting for 6 hours;

s2: adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the mixture obtained in the step S1, mixing, and then putting the mixture into a high-speed stirrer for stirring at a speed of 650r/min for 30min to obtain the self-hardening curing agent;

the modified polyurethane is prepared by the following steps:

s21: adding 18.8g of bisphenol A, 72g of dimethylamine aqueous solution and 42.5g of formaldehyde aqueous solution into a reaction kettle, heating for 4 hours at 90 ℃, cooling, separating out an organic phase, and carrying out vacuum distillation at 100 ℃ and 1.33KPa to obtain a catalyst A;

s22: adding 1g of catalyst A into 10mL of butyl acetate to obtain a butyl acetate solution of the catalyst A;

s23: under the protection of nitrogen, adding 100g of 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser, stirring for 15min, heating to 80 ℃, dropwise adding 0.5g of a butyl acetate solution of a catalyst A, controlling the dropwise adding speed to be 2 drops/s, controlling the temperature to be 100 ℃ after the dropwise adding is finished within 30min, carrying out heat preservation reaction for 6h, adding benzoyl chloride with equal mass for 1.5h every time in three times during the reaction, adding 6g of benzoyl chloride with total mass, continuing stirring for 1h to terminate the reaction, stopping heating and stirring, cooling and discharging to obtain the modified polyurethane.

Comparative example 1:

comparative example 1 differs from example 1 in that no modified polyurethane was added.

Comparative example 2:

comparative example 2A curing agent for a furan resin for casting, which was disclosed in Chinese patent CN201811202470.0, was used.

Detecting the curing agents of examples 1-4 and comparative examples 1-2, weighing 1000g of Dalin standard sand, adding the Dalin standard sand into a blade type laboratory sand mixer, respectively adding 5g of the curing agent, stirring for 1min, discharging the sand, beating into 8-shaped test blocks, detecting the demolding time and the tensile strength for 1h, 4h, 8h and 24h, and executing the standard GB-2684;

the results are shown in the following table:

as is apparent from the above table, the mold release time of examples reached 12 to 16min, the mold release time of comparative example 1 without adding the modified polyurethane was 25min, the mold release time of comparative example 2 using a curing agent for cast self-hardening furan resin disclosed in Chinese patent CN201811202470.0 was 22min, the tensile strength after 1h of example was 0.274 to 0.289MPa, the tensile strength of comparative example 1 without adding the modified polyurethane was 0.114MPa, the tensile strength of comparative example 2 using a curing agent for cast self-hardening furan resin disclosed in Chinese patent CN201811202470.0 was 0.196MPa, the tensile strength after 4h of example was 0.521 to 0.534MPa, the tensile strength of comparative example 1 without adding the modified polyurethane was 0.226MPa, the tensile strength of comparative example 2 using a curing agent for cast self-hardening furan resin disclosed in Chinese patent CN201811202470.0 was 0.378MPa, the tensile strength after 8h of example was 0.837 to 0.849MPa, the tensile strength of comparative example 1 without adding the modified polyurethane is 0.431MPa, the tensile strength of comparative example 2 using the curing agent for the casting self-hardening furan resin disclosed in Chinese patent CN201811202470.0 is 0.696MPa, the tensile strength after 24h of example is 1.589-1.597MPa, the tensile strength of comparative example 1 without adding the modified polyurethane is 0.578MPa, the tensile strength of comparative example 2 using the curing agent for the casting self-hardening furan resin disclosed in Chinese patent CN201811202470.0 is 0.824MPa, the data of comparative example 2 is obviously superior to that of comparative example 1, the data of the example is also obviously superior to that of comparative example 2, the example with the modified polyurethane is used for increasing the tensile strength of the sand core, and the overall performance is increased compared with the prior art.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims (5)

1. The self-hardening curing agent is characterized by comprising the following components in parts by weight:

10-20 parts of sodium fluosilicate, 20-30 parts of glycerol triacetate, 10-20 parts of propylene carbonate, 1-5 parts of sorbitol, 1-5 parts of silica sol and 40-60 parts of modified polyurethane;

the self-hardening curing agent is prepared by the following steps:

s1: adding acetone as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 80-90 ℃, and reacting for 2-6 h;

s2: adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the step S1, mixing, and then putting the mixture into a high-speed stirrer for stirring at the speed of 550-650r/min for 20-30min to obtain the self-hardening curing agent;

the modified polyurethane is prepared by the following steps:

s21: adding an aqueous solution of bisphenol A, dimethylamine and an aqueous solution of formaldehyde into a reaction kettle, heating and cooling to obtain a catalyst A;

s22: adding the catalyst A into butyl acetate to obtain a butyl acetate solution of the catalyst A;

s23: under the protection of nitrogen, adding 1, 4-diisocyanatobutane into a dry four-neck round-bottom flask provided with a stirrer, a thermometer and a reflux condenser, dropwise adding a butyl acetate solution of a catalyst A, carrying out heat preservation reaction, adding benzoyl chloride with equal mass for three times during the reaction, cooling and discharging to obtain the modified polyurethane.

2. The self-hardening curing agent according to claim 1, wherein the mass fraction of the aqueous solution of dimethylamine in step S21 is 25%, the mass fraction of the aqueous solution of formaldehyde is 40%, and the ratio of the amounts of the aqueous solutions of bisphenol a and dimethylamine to the amount of the aqueous solution of formaldehyde is 18.8 g: 72 g: 42.5 g.

3. The self-hardening curing agent according to claim 1, wherein the amount ratio of catalyst a to butyl acetate in step S22 is 1 g: 10 mL.

4. The self-curing agent as claimed in claim 1, wherein the ratio of the 1, 4-diisocyanatobutane, the butyl acetate solution of catalyst A and the benzoyl chloride in step S23 is 100-110 g: 0.5 g: 3-6 g.

5. The method for preparing the self-hardening curing agent according to claim 1, wherein the method for preparing the self-hardening curing agent specifically comprises the following steps:

s61: adding acetone as a solvent into the modified polyurethane, stirring, then adding sodium fluosilicate, heating to 80-90 ℃, and reacting for 2-6 h;

s62: and (4) adding glycerol triacetate, propylene carbonate, sorbitol and silica sol into the step S61, mixing, and then putting into a high-speed stirrer for stirring at 550-650r/min for 20-30min to obtain the self-hardening curing agent.