Environment-friendly modified furan resin for casting and preparation method thereof

Abstract

The invention discloses environment-friendly modified furan resin for casting and a preparation method thereof, and belongs to the technical field of furan resin preparation. The environment-friendly modified furan resin for casting is prepared from the following components in parts by weight: 18 to 26 parts of furfural, 24 to 38 parts of composite furfuryl alcohol, 1 to 4 parts of sodium hydroxide, 2 to 5 parts of an environment-friendly flowable agent, 2 to 6 parts of a reinforcing agent, 0.8 to 2.4 parts of a stabilizer and 0.5 to 1.5 parts of a de-foaming agent, the environment-friendly flowable agent is prepared from octadecane-9, 12, 15-trienoic acid, tetraethylene glycol, formic acid and acetic anhydride, and the de-foaming agent is prepared from octadecane-9, 12, 15-trienoic acid. The reinforcing agent is prepared from starch, polyethylene glycol, 1, 6-hexamethylenediamine, L-glutamic acid and propylene carbonate. The modified furan resin prepared by the method has excellent environmental protection property, toughness, thermal stability and fluidity.

Description

Technical Field

[0001] The invention belongs to the technical field of furan resin preparation, and particularly relates to environmentally friendly modified furan resin for casting and a preparation method thereof. Background Art

[0002] Furan resin is an important casting resin with excellent process performance and physical and mechanical properties. It is a general term for resins made by polycondensation reaction of furfuryl alcohol and furfural with furan ring as raw materials. The application of furan resin in the foundry industry began in the 1980s. With the continuous development of casting technology, furan resin sand process has gradually occupied a dominant position. However, there are some problems in the production and use of traditional furan resin, such as dependence on scarce petroleum resources for raw materials, serious pollution in the production process, and difficulty in controlling the quality of castings.

[0003] The main raw materials of traditional furan resin are phenol, formaldehyde, urea and furfuryl alcohol, etc. These raw materials will produce a large amount of wastewater, waste and solid waste during the production process, causing serious pollution to the environment. At the same time, these harmful substances will be released in large quantities during the high-temperature molten metal pouring and the sand removal and cleaning of castings, further polluting the environment and endangering human health. In addition, the application of traditional furan resin sand technology in the production of steel castings and aluminum castings is also subject to certain restrictions. For steel castings, due to the large amount and speed of furan resin sand, poor thermal conductivity, high high temperature strengthening and sulfur content of curing agent, steel castings are prone to casting defects such as hot cracking, carburization, sulfurization and pores, making it difficult to control their quality. For aluminum castings, the high temperature strength makes aluminum castings have a serious tendency to hot cracking, and sand removal is also very difficult.

[0004] Patent CN 113956417B discloses a method for preparing a modified furan resin, wherein formaldehyde, urea and furfural residue are used as raw materials to synthesize urea-formaldehyde resin under alkaline conditions, and then furfuryl alcohol and urea-formaldehyde resin undergo resinification reaction under acidic conditions to synthesize urea-formaldehyde furan resin. Adding furfural residue can modify the strength performance of urea-formaldehyde furan resin and reduce the content of free aldehyde. The process of the invention is simple, safe and reliable, and the tensile strength of the resin is improved. However, the environmental protection, toughness and fluidity of the furan resin prepared by this method still have room for improvement. Summary of the invention

[0005] The purpose of the present invention is to provide an environmentally friendly modified furan resin for casting and a preparation method thereof, so as to solve the technical problems of poor environmental performance, toughness and fluidity of the furan resin in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention provides an environmentally friendly modified furan resin for casting, which is composed of the following components in parts by weight: 18-26 parts of furfural, 24-38 parts of composite furfuryl alcohol, 1-4 parts of sodium hydroxide, 2-5 parts of an environmentally friendly flow agent, 2-6 parts of an enhancer, 0.8-2.4 parts of a stabilizer, and 0.5-1.5 parts of a defoamer, wherein the environmentally friendly flow agent is prepared from octadecane-9,12,15-trienoic acid, tetraethylene glycol, formic acid and acetic anhydride, and the enhancer is prepared from starch, polyethylene glycol, 1,6-hexanediamine, L-glutamic acid and propylene carbonate.

[0008] Preferably, the method for preparing the environmentally friendly flow agent comprises the following steps:

[0009] Q1: Add 18-decane-9,12,15-trienoic acid, tetraethylene glycol and tetrabutyl titanate into a container with a thermometer and a magnetic stirrer, then introduce nitrogen and heat the reaction. After the reaction is completed, cool, wash, transfer to a single-necked flask, and evaporate under reduced pressure to obtain product 1;

[0010] Q2: Add product 1 and strongly acidic cation exchange resin to a container equipped with a thermometer, a serpentine condenser and a constant pressure funnel, heat the container, then drop a mixed solution of formic acid and hydrogen peroxide solution through the constant pressure funnel to react. After the reaction is completed, transfer the upper clear liquid to a separating funnel, let it stand, remove the lower liquid, add deionized water, wash, and evaporate under vacuum to obtain product 2;

[0011] Q3: Add product 2, acetic anhydride, strongly acidic cation exchange resin and cyclohexane into a container equipped with a thermometer and a condenser, heat to react, and after the reaction is completed, cool, wash the supernatant, and perform vacuum reduced pressure rotary evaporation to obtain an environmentally friendly flowable agent.

[0012] In the above process, the synthetic reaction formula of the environmentally friendly flow agent is as follows:

[0013]

[0014] The results of mass spectrometry analysis of product 1 are: m / z: 718.57 (100.0%), 719.58 (48.8%), 720.58 (13.1%), 721.58 (2.4%); the results of mass spectrometry analysis of product 2 are: m / z: 782.55 (100.0%), 783.56 (48.9%), 784.56 (14.0%), 785.56 (2.8%); the results of mass spectrometry analysis of the environmentally friendly flow agent are: m / z: 1190.68 (100.0%), 1191.68 (64.9%), 1192.69 (26.8%), 1193.69 (7.9%), 1191.69 (2.0%), 1194.69 (1.8%).

[0015] Preferably, in Q1, the molar ratio of octadecane-9,12,15-trienoic acid and tetraethylene glycol is (1.9-2.2): (0.9-1.2), the heating reaction temperature is 140-160°C, the reaction time is 6-8h, and the mixture is first washed with saturated sodium bicarbonate solution and saturated sodium chloride solution, and then washed with deionized water and ethyl acetate until neutral; in Q2, the amount ratio of product 1, strong acid cation exchange resin, formic acid and hydrogen peroxide solution is (35.93-71.88) g: (3.4-6.5) g: (4.9-9.9) g: (21.9-38.8) mL, the heating treatment temperature is 60-80°C, the volume fraction of hydrogen peroxide solution is 30vt%, and the reaction time is 6-8h.

[0016] Preferably, in Q3, the dosage ratio of product 2, acetic anhydride, strong acidic cation exchange resin and cyclohexane is (32.84-43.79) g: (20.4-38.76) g: (4-6.5) g: (20-45) mL, the heating reaction temperature is 110-130°C, the time is 6-8h, and the reaction is washed with deionized water.

[0017] Preferably, the method for preparing the enhancer comprises the following steps:

[0018] S1: Add starch, polyethylene glycol and glycerol into a container, stir and mix well, then add citric acid and stir to obtain intermediate A;

[0019] S2: Add 1,6-hexanediamine to a container, then add p-toluenesulfonic acid, heat and sulfonate, add L-glutamic acid, introduce nitrogen, heat and react, perform vacuum reaction, and after the reaction is completed, cool to obtain intermediate B;

[0020] S3: adding intermediate B and propylene carbonate into a container, heating for reaction under nitrogen protection, and after the reaction is completed, recrystallizing and drying to obtain intermediate C;

[0021] S4: Add intermediate A to a container equipped with condensation reflux, magnetic stirring and vacuum devices, heat, then add intermediate C and stannous octoate, heat under nitrogen protection, react, continue to heat and vacuum, and after the reaction is completed, cool to obtain an enhancer.

[0022] In the above process, starch, polyethylene glycol and glycerol are first used as raw materials and citric acid is used as a catalyst to prepare intermediate A, and then 1,6-hexanediamine and L-glutamic acid are used as raw materials to undergo hydroxylamine reaction to obtain intermediate B, and intermediate B is then reacted with propylene carbonate to undergo amidation reaction to obtain intermediate C, and then intermediate A and intermediate C are used as raw materials to catalyze urethane exchange melt condensation to prepare an enhancer.

[0023] Preferably, in S1, the dosage ratio of starch, polyethylene glycol, glycerol and citric acid is (20-25) g: (100-125) g: (32-40) mL: (0.2-0.5) g, and the stirring time is 10-20 min.

[0024] Preferably, in S2, the molar ratio of 1,6-hexanediamine and L-glutamic acid is (2-2.6): (1-1.2), the heating sulfonation temperature is 80-85°C, the time is 30-45min, nitrogen is introduced for 5-10min, the heating reaction temperature is 150-170°C, the reaction time is 20-30min, the vacuum reaction pressure is -0.05 to -0.08MPa, and the reaction time is 6-10h; in S3, the amount ratio of intermediate B to propylene carbonate is (9-13)g: (16.5-24.1)g, the heating reaction temperature is 110-130°C, the reaction time is 4-6h, recrystallization is carried out with ethanol, the drying temperature is 50-60°C, and the time is 24-30h.

[0025] Preferably, in S4, the usage ratio of intermediate A, intermediate C and stannous octoate is (10-12) g: (9-11.8) g: (0.57-0.71) g, heated to 90-95°C, the heating reaction temperature is 150-170°C, the reaction time is 4-6h, the heating and vacuum reaction temperature is 190-210°C, the vacuum pressure is -0.05 to -0.09 MPa, and the reaction time is 20-24h.

[0026] Preferably, the method for preparing the environmentally friendly modified furan resin for casting comprises the following steps:

[0027] Step 1: adding starch to a container filled with distilled water, and after magnetic stirring, adjusting the pH to obtain a starch solution, and then adding furfuryl alcohol and glyoxal to the starch solution, continuing to adjust the pH, heating and stirring, to obtain composite furfuryl alcohol;

[0028] Step 2: adding the composite furfuryl alcohol and furfural into a reaction kettle, stirring and mixing them evenly, heating, and then slowly adding sodium hydroxide, and continuing heating and reacting to obtain a composite resin;

[0029] Step 3: Then, add an environmentally friendly flow agent, a reinforcing agent, a stabilizer and a defoaming agent to the reactor in sequence, continue stirring the reaction, and after the reaction is completed, cool, filter and dry to obtain an environmentally friendly modified furan resin for casting.

[0030] Preferably, in the step 1, the dosage ratio of starch to distilled water is (1-4) g: (5-10) mL, the magnetic stirring time is 2-5 min, the pH is adjusted to 10-10.2 with a sodium hydroxide solution with a volume fraction of 30 vt%, the dosage ratio of starch solution, furfuryl alcohol and glyoxal is (5-8) mL: (6-9) g: (0.5-1.2) g, the pH is further adjusted to 2-2.2 with a p-toluenesulfonic acid aqueous solution with a mass fraction of 65 wt%, the heating and stirring temperature is 50-70 ° C, and the time is 2-4 h.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] 1. The present invention first uses octadecane-9,12,15-trienoic acid, tetraethylene glycol, formic acid and acetic anhydride as raw materials to prepare an environmentally friendly flow agent, and then uses starch, polyethylene glycol, 1,6-hexanediamine, L-glutamic acid and propylene carbonate as raw materials to prepare a reinforcing agent, which is added to the modified furan resin to effectively improve its toughness, thermal stability and fluidity. The presence of composite furfuryl alcohol can also reduce the gas emission of the furan resin, improve the curing quality and performance of the resin, and then improve the density and strength of the resin.

[0033] 2. The present invention adds the prepared environmentally friendly flow agent to the modified furan resin, which can effectively improve its toughness, fluidity and environmental protection. The environmentally friendly flow agent contains a long carbon chain. When added to the furan resin, it can penetrate between the resin molecular chains, play a role of lubrication and dispersion, reduce the interaction force between the resin molecular chains, and make the resin softer and easier to deform. The introduced weak polar ether bonds can reduce the polarity of the environmentally friendly flow agent, making the interaction between it and the resin molecular chain more gentle, reducing the rigidity of the resin molecular chain, and improving the flexibility of the resin; the flexible long chain and the weak polar ether bond reduce the interaction force between the resin molecular chains, making the resin molecular chains easier to slide and rearrange, reducing the viscosity of the melt, and improving the fluidity of the resin, making the resin easier to flow and fill the mold during the processing, thereby improving the molding efficiency and quality of the product; and the raw materials used in the preparation process of the environmentally friendly flow agent are renewable and degradable, and no toxic and harmful substances are added, thereby improving the environmental protection of the furan resin.

[0034] 3. The prepared reinforcing agent is added to the modified furan resin in the present invention, which can effectively improve its strength, toughness and thermal stability. The ester bonds and amide bonds contained in the reinforcing agent act as cross-linking points in the furan resin, which can increase the interaction force between the resin molecular chains and improve the strength of the resin. The presence of the cross-linked structure can also disperse stress, prevent the material from brittle fracture when subjected to external force, and improve toughness. The hydrogen bonds contained in the reinforcing agent can increase the interaction force between molecules, so that the resin molecular chains are arranged more closely together, thereby improving the strength and thermal stability. DETAILED DESCRIPTION

[0035] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1: This example discloses a method for preparing an environmentally friendly flow agent, comprising the following steps:

[0037] Q1: 2.87 g of octadecane-9,12,15-trienoic acid, 1.02 g of tetraethylene glycol and 0.025 g of tetrabutyl titanate were added to a container with a thermometer and a magnetic stirrer, and then nitrogen was introduced. The temperature was raised to 160°C for reaction for 8 h. After the reaction was completed, the mixture was cooled, first washed with a saturated sodium bicarbonate solution and a saturated sodium chloride solution, and then washed with deionized water and ethyl acetate until neutral, and then transferred to a single-necked flask and evaporated under reduced pressure to obtain product 1;

[0038] Q2: 58.85 g of product 1 and 5.05 g of strongly acidic cation exchange resin were added to a container equipped with a thermometer, a serpentine condenser and a constant pressure funnel, and the temperature was raised to 60°C. Then, a mixed solution of 7.4 g of formic acid and 30.12 mL of a 30 vt% hydrogen peroxide solution was added dropwise through the constant pressure funnel, and the reaction was continued for 8 h. After the reaction was completed, the supernatant liquid was transferred to a separating funnel, allowed to stand, the lower layer of liquid was removed, deionized water was added, the mixture was washed, and vacuum reduced pressure rotary evaporation was performed to obtain product 2;

[0039] Q3: Add 38.12g of product 2, 29.51g of acetic anhydride, 5.75g of strongly acidic cation exchange resin and 32.5mL of cyclohexane into a container equipped with a thermometer and a condenser, and heat to 120°C for 8h. After the reaction is completed, cool and wash the supernatant with deionized water, and evaporate under vacuum to obtain an environmentally friendly flowable agent.

[0040] This embodiment discloses a method for preparing an enhancer, comprising the following steps:

[0041] S1: Add 22.5 g starch, 112.5 g polyethylene glycol and 36 mL glycerol into a container, stir and mix well, then add 0.35 g citric acid and stir for 15 min to obtain intermediate A;

[0042] S2: 1.334 g of 1,6-hexanediamine was added to a container, followed by 0.045 g of p-toluenesulfonic acid, and the mixture was heated at 85°C for 45 min, and then 0.791 g of L-glutamic acid was added. Nitrogen was introduced for 10 min, and the mixture was heated at 170°C for 30 min, and then the mixture was reacted under a vacuum of -0.08 MPa for 10 h. After the reaction was completed, the mixture was cooled to obtain intermediate B.

[0043] S3: 11 g of intermediate B and 20.3 g of propylene carbonate were added to a container, heated at 130° C. for 6 h under nitrogen protection, and after the reaction, recrystallized with ethanol and dried at 60° C. for 24 h to obtain intermediate C;

[0044] S4: Add 11g of intermediate A to a container equipped with condensation reflux, magnetic stirring and vacuum devices, heat at 95°C, then add 10.4g of intermediate C and 0.64g of stannous octoate, heat at 160°C for 6h under nitrogen protection, continue to heat to 210°C, evacuate, react at -0.09MPa for 24h, and after the reaction is completed, cool to obtain an enhancer.

[0045] The present embodiment discloses an environmentally friendly modified furan resin for casting, which is composed of the following components by weight: 22 parts of furfural, 31 parts of complex furfuryl alcohol, 2.5 parts of sodium hydroxide, 3.5 parts of environmentally friendly flow agent, 4 parts of enhancer, 1.6 parts of stabilizer, and 1 part of defoamer.

[0046] This embodiment discloses a method for preparing an environmentally friendly modified furan resin for casting, comprising the following steps:

[0047] Step 1: Add 2.5g of starch to a container containing 7.5mL of distilled water, stir magnetically for 5min, adjust pH=10 with a 30vt% sodium hydroxide solution to obtain a starch solution, then add 7.5g of furfuryl alcohol and 0.85g of glyoxal to 6.5mL of the starch solution, continue to adjust pH=2 with a 65wt% p-toluenesulfonic acid aqueous solution, heat and stir at 60°C for 4h to obtain composite furfuryl alcohol;

[0048] Step 2: adding the composite furfuryl alcohol and furfural into a reaction kettle, stirring and mixing them evenly, heating, and then slowly adding sodium hydroxide, and continuing heating and reacting to obtain a composite resin;

[0049] Step 3: Then, add an environmentally friendly flow agent, a reinforcing agent, a stabilizer and a defoaming agent to the reactor in sequence, continue stirring the reaction, and after the reaction is completed, cool, filter and dry to obtain an environmentally friendly modified furan resin for casting.

[0050] Example 2: This example discloses a method for preparing an environmentally friendly flow agent, comprising the following steps:

[0051] Q1: 2.66 g of octadecane-9,12,15-trienoic acid, 0.873 g of tetraethylene glycol and 0.025 g of tetrabutyl titanate were added to a container containing a thermometer and a magnetic stirrer, and then nitrogen was introduced, and the temperature was raised to 160°C for reaction for 8 hours. After the reaction was completed, the mixture was cooled, first washed with a saturated sodium bicarbonate solution and a saturated sodium chloride solution, and then washed with deionized water and ethyl acetate until neutral, and then transferred to a single-necked flask, and vacuum evaporated under reduced pressure to obtain product 1;

[0052] Q2: 35.93 g of product 1 and 3.4 g of strongly acidic cation exchange resin were added to a container equipped with a thermometer, a serpentine condenser and a constant pressure funnel, and the temperature was raised to 60°C. Then, a mixed solution of 4.9 g of formic acid and 21.9 mL of a 30 vt% hydrogen peroxide solution was added dropwise through the constant pressure funnel, and the reaction was continued for 8 h. After the reaction was completed, the supernatant liquid was transferred to a separating funnel, allowed to stand, the lower layer of liquid was removed, deionized water was added, the mixture was washed, and vacuum reduced pressure rotary evaporation was performed to obtain product 2;

[0053] Q3: Add 32.84 g of product 2, 20.4 g of acetic anhydride, 6.5 g of strongly acidic cation exchange resin and 20 mL of cyclohexane into a container equipped with a thermometer and a condenser, and heat to react at 120°C for 8 h. After the reaction is completed, cool the container, wash the supernatant with deionized water, and evaporate the supernatant under vacuum to obtain an environmentally friendly flowable agent.

[0054] This embodiment discloses a method for preparing an enhancer, comprising the following steps:

[0055] S1: Add 25 g starch, 125 g polyethylene glycol and 32 mL glycerol into a container, stir and mix well, then add 0.5 g citric acid and stir for 15 min to obtain intermediate A;

[0056] S2: 1.16 g of 1,6-hexanediamine was added to a container, followed by 0.045 g of p-toluenesulfonic acid, and the mixture was heated at 85°C for 45 min, and then 0.735 g of L-glutamic acid was added. Nitrogen was introduced for 10 min, and the mixture was heated at 170°C for 30 min, and then the mixture was reacted under a vacuum of -0.08 MPa for 10 h. After the reaction was completed, the mixture was cooled to obtain intermediate B.

[0057] S3: 9 g of intermediate B and 16.5 g of propylene carbonate were added to a container, heated at 130° C. for 6 h under nitrogen protection, and after the reaction, recrystallized with ethanol and dried at 60° C. for 24 h to obtain intermediate C;

[0058] S4: Add 10g of intermediate A to a container equipped with condensation reflux, magnetic stirring and vacuum devices, heat at 95°C, then add 11.8g of intermediate C and 0.57g of stannous octoate, heat at 160°C for 6h under nitrogen protection, continue to heat to 210°C, evacuate, react at -0.09MPa for 24h, and after the reaction is completed, cool to obtain an enhancer.

[0059] The present embodiment discloses an environmentally friendly modified furan resin for casting, which is composed of the following components by weight: 18 parts of furfural, 24 parts of compound furfuryl alcohol, 1 part of sodium hydroxide, 2 parts of environmentally friendly flow agent, 2 parts of enhancer, 0.8 parts of stabilizer, and 0.5 parts of defoamer.

[0060] This embodiment discloses a method for preparing an environmentally friendly modified furan resin for casting, comprising the following steps:

[0061] Step 1: add 1g of starch to a container containing 10mL of distilled water, stir magnetically for 5min, adjust pH=10 with a 30vt% sodium hydroxide solution to obtain a starch solution, then add 6g of furfuryl alcohol and 0.5g of glyoxal to 5mL of the starch solution, continue to adjust pH=2 with a 65wt% p-toluenesulfonic acid aqueous solution, heat and stir at 60°C for 4h to obtain composite furfuryl alcohol;

[0062] Step 2: adding the composite furfuryl alcohol and furfural into a reaction kettle, stirring and mixing them evenly, heating, and then slowly adding sodium hydroxide, and continuing heating and reacting to obtain a composite resin;

[0063] Step 3: Then, add an environmentally friendly flow agent, a reinforcing agent, a stabilizer and a defoaming agent to the reactor in sequence, continue stirring the reaction, and after the reaction is completed, cool, filter and dry to obtain an environmentally friendly modified furan resin for casting.

[0064] Example 3: This example discloses a method for preparing an environmentally friendly flow agent, comprising the following steps:

[0065] Q1: 3.08 g of octadecane-9,12,15-trienoic acid, 1.164 g of tetraethylene glycol and 0.025 g of tetrabutyl titanate were added to a container containing a thermometer and a magnetic stirrer, and then nitrogen was introduced, and the temperature was raised to 160°C for reaction for 8 h. After the reaction was completed, the mixture was cooled, first washed with a saturated sodium bicarbonate solution and a saturated sodium chloride solution, and then washed with deionized water and ethyl acetate until neutral, and then transferred to a single-necked flask, and vacuum evaporated under reduced pressure to obtain product 1;

[0066] Q2: 71.88 g of product 1 and 6.5 g of strongly acidic cation exchange resin were added to a container equipped with a thermometer, a serpentine condenser and a constant pressure funnel, and the temperature was raised to 60°C. Then, a mixed solution of 9.9 g of formic acid and 38.8 mL of a 30 vt% hydrogen peroxide solution was added dropwise through the constant pressure funnel, and the reaction was continued for 8 h. After the reaction was completed, the supernatant liquid was transferred to a separating funnel, allowed to stand, the lower layer of liquid was removed, deionized water was added, the mixture was washed, and vacuum reduced pressure rotary evaporation was performed to obtain product 2;

[0067] Q3: Add 43.79 g of product 2, 38.76 g of acetic anhydride, 4 g of strongly acidic cation exchange resin and 45 mL of cyclohexane into a container equipped with a thermometer and a condenser, and heat to react at 120°C for 8 h. After the reaction is completed, cool, wash the supernatant with deionized water, and evaporate under vacuum to obtain an environmentally friendly flowable agent.

[0068] This embodiment discloses a method for preparing an enhancer, comprising the following steps:

[0069] S1: Add 20 g starch, 100 g polyethylene glycol and 40 mL glycerol into a container, stir and mix well, then add 0.2 g citric acid and stir for 15 min to obtain intermediate A;

[0070] S2: 1.508 g of 1,6-hexanediamine was added to a container, followed by 0.045 g of p-toluenesulfonic acid, and the mixture was heated at 85°C for 45 min, and then 0.882 g of L-glutamic acid was added. Nitrogen was introduced for 10 min, and the mixture was heated at 170°C for 30 min, and then the mixture was reacted under a vacuum of -0.08 MPa for 10 h. After the reaction was completed, the mixture was cooled to obtain intermediate B.

[0071] S3: 13 g of intermediate B and 24.1 g of propylene carbonate were added to a container, heated at 130° C. for 6 h under nitrogen protection, and after the reaction, recrystallized with ethanol and dried at 60° C. for 24 h to obtain intermediate C;

[0072] S4: Add 12g of intermediate A to a container equipped with condensation reflux, magnetic stirring and vacuum devices, heat at 95°C, then add 9g of intermediate C and 0.71g of stannous octoate, heat at 160°C for 6h under nitrogen protection, continue to heat to 210°C, evacuate, react at -0.09MPa for 24h, and after the reaction is completed, cool to obtain an enhancer.

[0073] The present embodiment discloses an environmentally friendly modified furan resin for casting, which is composed of the following components by weight: 26 parts of furfural, 38 parts of composite furfuryl alcohol, 4 parts of sodium hydroxide, 5 parts of environmentally friendly flow agent, 6 parts of enhancer, 2.4 parts of stabilizer, and 1.5 parts of defoamer.

[0074] This embodiment discloses a method for preparing an environmentally friendly modified furan resin for casting, comprising the following steps:

[0075] Step 1: Add 4g of starch to a container containing 5mL of distilled water, stir magnetically for 5min, adjust pH=10 with a 30vt% sodium hydroxide solution to obtain a starch solution, then add 9g of furfuryl alcohol and 1.2g of glyoxal to 8mL of the starch solution, continue to adjust pH=2 with a 65wt% p-toluenesulfonic acid aqueous solution, heat and stir at 60°C for 4h to obtain composite furfuryl alcohol;

[0076] Step 2: adding the composite furfuryl alcohol and furfural into a reaction kettle, stirring and mixing them evenly, heating, and then slowly adding sodium hydroxide, and continuing heating and reacting to obtain a composite resin;

[0077] Step 3: Then, add an environmentally friendly flow agent, a reinforcing agent, a stabilizer and a defoaming agent to the reactor in sequence, continue stirring the reaction, and after the reaction is completed, cool, filter and dry to obtain an environmentally friendly modified furan resin for casting.

[0078] Example 4: This example discloses a method for preparing an environmentally friendly flow agent, comprising the following steps:

[0079] Q1: 2.73 g of octadecane-9,12,15-trienoic acid, 0.951 g of tetraethylene glycol and 0.025 g of tetrabutyl titanate were added to a container containing a thermometer and a magnetic stirrer, and then nitrogen was introduced. The temperature was raised to 160°C for reaction for 8 h. After the reaction was completed, the mixture was cooled, first washed with a saturated sodium bicarbonate solution and a saturated sodium chloride solution, and then washed with deionized water and ethyl acetate until neutral, and then transferred to a single-necked flask and evaporated under reduced pressure to obtain product 1;

[0080] Q2: 45.12 g of product 1 and 4.8 g of strongly acidic cation exchange resin were added to a container equipped with a thermometer, a serpentine condenser and a constant pressure funnel, and the temperature was raised to 60°C. Then, a mixed solution of 5.2 g of formic acid and 25.3 mL of a 30 vt% hydrogen peroxide solution was added dropwise through the constant pressure funnel, and the reaction was continued for 8 h. After the reaction was completed, the supernatant liquid was transferred to a separating funnel, allowed to stand, the lower layer of liquid was removed, deionized water was added, the mixture was washed, and vacuum reduced pressure rotary evaporation was performed to obtain product 2;

[0081] Q3: Add 36.12g of product 2, 25.12g of acetic anhydride, 4.5g of strongly acidic cation exchange resin and 25mL of cyclohexane into a container equipped with a thermometer and a condenser, and heat to 120°C for 8h. After the reaction is completed, cool and wash the supernatant with deionized water, and evaporate under vacuum to obtain an environmentally friendly flowable agent.

[0082] This embodiment discloses a method for preparing an enhancer, comprising the following steps:

[0083] S1: Add 21 g starch, 105 g polyethylene glycol and 34 mL glycerol into a container, stir and mix well, then add 0.3 g citric acid and stir for 15 min to obtain intermediate A;

[0084] S2: 1.214 g of 1,6-hexanediamine was added to a container, followed by 0.045 g of p-toluenesulfonic acid, and the mixture was heated at 85°C for 45 min, and then 0.759 g of L-glutamic acid was added. Nitrogen was introduced for 10 min, and the mixture was heated at 170°C for 30 min, and then the mixture was reacted under a vacuum of -0.08 MPa for 10 h. After the reaction was completed, the mixture was cooled to obtain intermediate B.

[0085] S3: 10 g of intermediate B and 18.4 g of propylene carbonate were added to a container, heated at 130° C. for 6 h under nitrogen protection, and after the reaction, recrystallized with ethanol and dried at 60° C. for 24 h to obtain intermediate C;

[0086] S4: Add 10.5g of intermediate A to a container equipped with condensation reflux, magnetic stirring and vacuum devices, heat at 95°C, then add 9.5g of intermediate C and 0.62g of stannous octoate, heat at 160°C for 6h under nitrogen protection, continue to heat to 210°C, evacuate, react at -0.09MPa for 24h, and after the reaction is completed, cool to obtain an enhancer.

[0087] The present embodiment discloses an environmentally friendly modified furan resin for casting, which is composed of the following components by weight: 20 parts of furfural, 26 parts of composite furfuryl alcohol, 2 parts of sodium hydroxide, 3 parts of environmentally friendly flow agent, 3 parts of enhancer, 0.9 parts of stabilizer, and 0.75 parts of defoamer.

[0088] This embodiment discloses a method for preparing an environmentally friendly modified furan resin for casting, comprising the following steps:

[0089] Step 1: Add 2g of starch to a container containing 6mL of distilled water, stir magnetically for 5min, adjust pH=10 with a 30vt% sodium hydroxide solution to obtain a starch solution, then add 7g of furfuryl alcohol and 0.7g of glyoxal to the 6mL starch solution, continue to adjust pH=2 with a 65wt% p-toluenesulfonic acid aqueous solution, heat and stir at 60°C for 4h to obtain composite furfuryl alcohol;

[0090] Step 2: adding the composite furfuryl alcohol and furfural into a reaction kettle, stirring and mixing them evenly, heating, and then slowly adding sodium hydroxide, and continuing heating and reacting to obtain a composite resin;

[0091] Step 3: Then, add an environmentally friendly flow agent, a reinforcing agent, a stabilizer and a defoaming agent to the reactor in sequence, continue stirring the reaction, and after the reaction is completed, cool, filter and dry to obtain an environmentally friendly modified furan resin for casting.

[0092] Comparative Example 1: Compared with Example 1, in the process of preparing the environmentally friendly modified furan resin for casting in Comparative Example 1, no environmentally friendly flow agent is added, and other conditions remain unchanged.

[0093] Comparative Example 2: Compared with Example 1, in Comparative Example 2, during the process of preparing the environmentally friendly modified furan resin for casting, no reinforcing agent is added, and other conditions remain unchanged.

[0094] Experimental example: The tensile properties of the samples were tested according to GB / T1040.1-2006, the thermal stability of the samples was tested according to ASTM E1131-08 (2014), and the fluidity of the samples was tested according to JB / T 7526-2008. The test results are shown in Table 1:

[0095] Table 1

[0096] project Tensile strength / MPa Mass loss / % <![CDATA[Viscosity / mPa·s -1 > Example 1 54.2 2.42 88.34 Example 2 53.8 2.45 88.12 Example 3 53.6 2.47 87.84 Example 4 53.7 2.46 87.91 Comparative Example 1 47.8 2.48 82.35 Comparative Example 2 47.6 3.12 87.75

[0097] From the test results in Table 1, it can be seen that the furan resins prepared in Examples 1-4 of the present invention have excellent flexibility, thermal stability and flow properties. From the comparison between Comparative Example 1 and Examples 1-4, it can be seen that the addition of an environmentally friendly flow agent can effectively improve the flexibility and flow properties of the furan resin; from the comparison between Comparative Example 2 and Examples 1-4, it can be seen that the addition of a reinforcing agent can effectively improve the flexibility and thermal stability of the furan resin.

[0098] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0099] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. Environmentally friendly modified furan resin for casting, characterized in that: The invention is composed of the following components in parts by weight: 18-26 parts of furfural, 24-38 parts of composite furfuryl alcohol, 1-4 parts of sodium hydroxide, 2-5 parts of environmentally friendly flow agents, 2-6 parts of enhancers, 0.8-2.4 parts of stabilizers, and 0.5-1.5 parts of defoamers, wherein the environmentally friendly flow agent is prepared from octadecane-9,12,15-trienoic acid, tetraethylene glycol, formic acid and acetic anhydride, and the enhancer is prepared from starch, polyethylene glycol, 1,6-hexanediamine, L-glutamic acid and propylene carbonate.

2. The environmentally friendly modified furan resin for casting according to claim 1, characterized in that: The preparation method of the environmentally friendly flow agent comprises the following steps: Q1: Add 18-decane-9,12,15-trienoic acid, tetraethylene glycol and tetrabutyl titanate into a container with a thermometer and a magnetic stirrer, then introduce nitrogen and heat the reaction. After the reaction is completed, cool, wash, transfer to a single-necked flask, and evaporate under reduced pressure to obtain product 1; Q2: Add product 1 and strongly acidic cation exchange resin to a container equipped with a thermometer, a serpentine condenser and a constant pressure funnel, heat the container, then drop a mixed solution of formic acid and hydrogen peroxide solution through the constant pressure funnel to react. After the reaction is completed, transfer the upper clear liquid to a separating funnel, let it stand, remove the lower liquid, add deionized water, wash, and evaporate under vacuum to obtain product 2; Q3: Add product 2, acetic anhydride, strongly acidic cation exchange resin and cyclohexane into a container equipped with a thermometer and a condenser, heat to react, and after the reaction is completed, cool, wash the supernatant, and perform vacuum reduced pressure rotary evaporation to obtain an environmentally friendly flowable agent.

3. The environmentally friendly modified furan resin for casting according to claim 2, characterized in that: In the Q1, the molar ratio of octadecane-9,12,15-trienoic acid and tetraethylene glycol is (1.9-2.2): (0.9-1.2), the heating reaction temperature is 140-160°C, the reaction time is 6-8h, and it is first washed with a saturated sodium bicarbonate solution and a saturated sodium chloride solution, and then washed with deionized water and ethyl acetate until neutral; in the Q2, the amount ratio of the product 1, the strong acid cation exchange resin, the formic acid and the hydrogen peroxide solution is (35.93-71.88)g: (3.4-6.5)g: (4.9-9.9)g: (21.9-38.8)mL, the heating treatment temperature is 60-80°C, the volume fraction of the hydrogen peroxide solution is 30vt%, and the reaction time is 6-8h.

4. The environmentally friendly modified furan resin for casting according to claim 2, characterized in that: In Q3, the usage ratio of product 2, acetic anhydride, strong acidic cation exchange resin and cyclohexane is (32.84-43.79) g: (20.4-38.76) g: (4-6.5) g: (20-45) mL, the heating reaction temperature is 110-130° C., the time is 6-8 h, and the reaction is washed with deionized water.

5. The environmentally friendly modified furan resin for casting according to claim 1, characterized in that: The preparation method of the enhancer comprises the following steps: S1: Add starch, polyethylene glycol and glycerol into a container, stir and mix well, then add citric acid and stir to obtain intermediate A; S2: Add 1,6-hexanediamine to a container, then add p-toluenesulfonic acid, heat and sulfonate, add L-glutamic acid, introduce nitrogen, heat and react, perform vacuum reaction, and after the reaction is completed, cool to obtain intermediate B; S3: adding intermediate B and propylene carbonate into a container, heating for reaction under nitrogen protection, and after the reaction is completed, recrystallizing and drying to obtain intermediate C; S4: Add intermediate A to a container equipped with condensation reflux, magnetic stirring and vacuum devices, heat, then add intermediate C and stannous octoate, heat under nitrogen protection, react, continue to heat and vacuum, and after the reaction is completed, cool to obtain an enhancer.

6. The environmentally friendly modified furan resin for casting according to claim 5, characterized in that: In S1, the dosage ratio of starch, polyethylene glycol, glycerol and citric acid is (20-25) g: (100-125) g: (32-40) mL: (0.2-0.5) g, and the stirring time is 10-20 min.

7. The environmentally friendly modified furan resin for casting according to claim 5, characterized in that: In the S2, the molar ratio of 1,6-hexanediamine and L-glutamic acid is (2-2.6): (1-1.2), the heating sulfonation temperature is 80-85°C, the time is 30-45min, nitrogen is introduced for 5-10min, the heating reaction temperature is 150-170°C, the reaction time is 20-30min, the vacuum reaction pressure is -0.05 to -0.08MPa, and the reaction time is 6-10h; in the S3, the amount ratio of intermediate B and propylene carbonate is (9-13)g: (16.5-24.1)g, the heating reaction temperature is 110-130°C, the reaction time is 4-6h, recrystallization is carried out with ethanol, the drying temperature is 50-60°C, and the time is 24-30h.

8. The environmentally friendly modified furan resin for casting according to claim 5, characterized in that: In the S4, the usage ratio of intermediate A, intermediate C and stannous octoate is (10-12) g: (9-11.8) g: (0.57-0.71) g, heated to 90-95°C, the heating reaction temperature is 150-170°C, the reaction time is 4-6h, the heating and vacuuming reaction temperature is 190-210°C, the vacuum pressure is -0.05 to -0.09 MPa, and the reaction time is 20-24h.

9. The method for preparing the environmentally friendly modified furan resin for casting according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: adding starch to a container filled with distilled water, and after magnetic stirring, adjusting the pH to obtain a starch solution, and then adding furfuryl alcohol and glyoxal to the starch solution, continuing to adjust the pH, heating and stirring, to obtain composite furfuryl alcohol; Step 2: adding the composite furfuryl alcohol and furfural into a reaction kettle, stirring and mixing them evenly, heating, and then slowly adding sodium hydroxide, and continuing heating and reacting to obtain a composite resin; Step 3: Then, add an environmentally friendly flow agent, a reinforcing agent, a stabilizer and a defoaming agent to the reactor in sequence, continue stirring the reaction, and after the reaction is completed, cool, filter and dry to obtain an environmentally friendly modified furan resin for casting.

10. The method for preparing the environmentally friendly modified furan resin for casting according to claim 9, characterized in that: In the step 1, the dosage ratio of starch to distilled water is (1-4) g: (5-10) mL, the magnetic stirring time is 2-5 min, the pH value is adjusted to 10-10.2 with a sodium hydroxide solution with a volume fraction of 30 vt%, the dosage ratio of starch solution, furfuryl alcohol and glyoxal is (5-8) mL: (6-9) g: (0.5-1.2) g, the pH value is further adjusted to 2-2.2 with a p-toluenesulfonic acid aqueous solution with a mass fraction of 65 wt%, the heating and stirring temperature is 50-70° C., and the time is 2-4 h.

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