A modified furan resin for 3D jet printing and preparation method thereof

Abstract

The present application belongs to a method for preparing a furan resin. When cardanol is currently used as a raw material for furan resin, the prepared furan resin is easy to be stratified during storage and use, resulting in a technical problem of strength reduction. A modified furan resin for 3D jet printing and a preparation method thereof are provided. Cardanol is modified using 2-urea-4-[1H]-pyrimidone functionalized with thiol, and a click chemistry reaction of a thiol-double bond occurs to obtain a cardanol derivative, and then a phenolic mixture and an aldehyde compound are reacted to obtain a cardanol-modified furan resin. By partially modifying the unsaturated double bond of cardanol, a polar hydrophilic motif is introduced, and intermolecular forces are increased, thereby increasing the strength of the furan resin. At the same time, the stratification phenomenon during storage and use is suppressed, and storage stability is improved. Then, a cardanol-modified furan resin with better performance is obtained, which has good application prospects.

Description

Technical Field

[0001] The present application relates to a method for preparing a furan resin, and specifically to a modified furan resin for 3D jet printing and a method for preparing the same. Background Art

[0002] Furan resin is a thermosetting resin with furfural and furfuryl alcohol as the main raw materials with furan rings, and is widely used in the field of casting binders. Although furan resin has many advantages, traditional furan resin uses formaldehyde or furfural and phenol as the main raw materials for its preparation. However, reagents such as furfuryl alcohol and phenol are relatively expensive, and the formaldehyde generated during the casting process is toxic and causes smoke pollution, and phenol also pollutes the environment and endangers human health. Therefore, the development of green and environmentally friendly furan resin is very important.

[0003] Based on the above situation, in practical applications, cardanol is often used as the raw material of furan resin. Cardanol is a phenolic compound extracted from natural cashew nut shell oil by advanced technology. It has the advantages of environmental friendliness, high biodegradability, low price, low odor, high temperature resistance and strong interaction with the contact surface. Its C15 straight chain containing unsaturated double bonds in the meta position can improve the toughness of furan resin and is a very excellent substitute for furfuryl alcohol and phenol. However, the unsaturation degree of the meta-side chain of common cardanol is 0-3, and the components are saturated, monoene, diene and triene structures respectively. The lipophilicity of the unsaturated carbon chain of the side group is too strong, which will cause the synthesized furan resin to be easily delaminated during storage and use, resulting in a decrease in strength after curing, which limits the widespread use of furan resin. Summary of the invention

[0004] The present application aims to solve the technical problem that when cardanol is currently used as a furan resin raw material, the prepared furan resin is easily delaminated during storage and use, resulting in a decrease in strength. The present application provides a modified furan resin for 3D jet printing and a preparation method thereof.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions: In a first aspect, the present application proposes a method for preparing a modified furan resin for 3D jet printing, comprising: Cardanol was modified with thiol-functionalized 2-ureido-4-[1H]-pyrimidinone to obtain cardanol derivatives through thiol-double bond click chemistry reaction; A phenolic mixture and an aldehyde compound are reacted to obtain a cardanol-modified furan resin; the phenolic mixture comprises the cardanol derivative and a phenolic compound.

[0006] Further, the step of reacting the phenolic mixture with the aldehyde compound comprises: allowing a phenolic mixture and an aldehyde compound to react in urea and an alkaline catalyst to obtain a pre-product; The pre-product is reacted with an alcohol compound in the presence of an acidic catalyst to obtain a cardanol-modified furan resin.

[0007] Further, the step of reacting the phenolic mixture with the aldehyde compound comprises: Mixing cardanol, cardanol derivatives, aldehyde compounds, urea and an alkaline catalyst, heating the mixture under a pH value of 8 to 9 for reflux reaction, and cooling the mixture to room temperature after the reaction is completed to obtain a pre-product; The pre-product, furfuryl alcohol and an acid catalyst are mixed, reacted after heating, and dehydrated after the reaction is completed to obtain cardanol-modified furan resin.

[0008] Furthermore, the phenolic compound is cardanol, the aldehyde compound is furfural, and the alcohol compound is furfuryl alcohol.

[0009] Further, the step of reacting the phenolic mixture with the aldehyde compound comprises: Cardanol, cardanol derivatives, furfural, urea and alkaline catalyst are placed in a reaction kettle at a molar ratio of 1:0.5:2:0.2:0.1, the pH value is controlled at 8-9, the temperature is raised to 100 °C, refluxed for 5 hours, and then cooled to room temperature to obtain a pre-product; The pre-product, furfuryl alcohol and acid catalyst were added into the reactor in a mass ratio of 100:200:1, the temperature was raised to 80°C, the reaction was carried out for 3 hours, and vacuum dehydration was carried out after the reaction was completed to obtain cardanol-modified furan resin.

[0010] Furthermore, the molar ratio of the cardanol to the cardanol derivative is 1:(0.5-1.5).

[0011] Furthermore, the mass ratio of the cardanol, the cardanol derivative, furfural, urea, the alkaline catalyst and furfuryl alcohol is 100: (50-150): (200-350): 20: (6-9): (40-75).

[0012] Further, the modification of cardanol using thiol-functionalized 2-ureido-4-[1H]-pyrimidinone comprises: Cardanol and thiol-functionalized 2-ureido-4-[1H]-pyrimidone were dissolved in dichloromethane, and azobisisobutyronitrile was added dropwise as an initiator. The mixture was refluxed at 80 °C for 8 h under stirring. After cooling, add water, extract and wash, and collect the dichloromethane layer; The collected dichloromethane layer is subjected to rotary evaporation, and after drying, a powder is obtained, which is a cardanol derivative.

[0013] Furthermore, the structure of the cardanol derivative includes: .

[0014] In a second aspect, the present application proposes a modified furan resin for 3D jet printing, which is obtained by using the above-mentioned method for preparing a modified furan resin for 3D jet printing.

[0015] Compared with the prior art, this application has the following beneficial effects: The present application proposes a method for preparing a modified furan resin for 3D jet printing, wherein cardanol is modified using thiol-functionalized 2-ureido-4-[1H]-pyrimidone, a thiol-double bond click chemistry reaction occurs, a cardanol derivative is obtained, and then a phenol mixture is reacted with an aldehyde compound to obtain a cardanol-modified furan resin. By partially modifying the unsaturated double bonds of cardanol and introducing polar hydrophilic moieties, the intermolecular forces are increased, thereby improving the strength of the furan resin. At the same time, the stratification phenomenon during storage and use is suppressed, the storage stability is improved, and a cardanol-modified furan resin with better performance is obtained, which has good application prospects.

[0016] The present application also proposes a modified furan resin for 3D jet printing, which has all the advantages of the above-mentioned preparation method of the modified furan resin for 3D jet printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a schematic diagram of the reaction principle of cardanol derivatives in the preparation method of modified furan resin for 3D jet printing in the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0023] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] Furan resin is a thermosetting resin containing a furan ring structure, which is mainly produced by the reaction of furfural and furfuryl alcohol. Due to its unique chemical structure and physical properties, this type of resin is widely used as a binder in the foundry industry. Furan resin can provide good bonding strength, heat resistance and chemical stability, making the surface of castings smooth, reducing sand holes and pores, and thus improving the overall quality of castings.

[0026] However, there are some problems in the production process of traditional furan resins that cannot be ignored. First, the cost of raw materials is high, especially furfuryl alcohol and phenol. The market prices of these chemical raw materials fluctuate greatly, which will directly affect the production cost of furan resin. Secondly, formaldehyde and phenol, as key raw materials or by-products in the preparation process, pose a serious threat to the environment and human health. Formaldehyde is a known carcinogen. Its volatilization into the air will not only cause air pollution, but also irritate and damage the respiratory system of operators. Phenol is also toxic. Long-term contact or inhalation can cause damage to the skin, eyes and respiratory system. In severe cases, it can affect the nervous system and liver and kidney function.

[0027] Cardanol is a phenolic compound derived from natural cashew nut shell liquid. It is extracted from cashew nut shell liquid through advanced refining technology. Its uniqueness lies in its environmental friendliness, high biodegradability, affordable price, low odor, excellent high temperature resistance and strong binding force with various contact surfaces. It is particularly worth mentioning that the meta position of the cardanol molecular structure contains a C15 straight chain with an unsaturated double bond. This special structure gives it the ability to improve the toughness of furan resin, making cardanol an ideal choice to replace traditional furfuryl alcohol and phenol. It not only performs well in performance, but also meets the current demand for environmentally friendly materials. The unsaturation of cardanol is one of its important chemical properties. The common unsaturation of the meta side chain of cardanol ranges from 0 to 3, which can be specifically divided into four structures: saturated, monoene (containing one double bond), diene (containing two double bonds) and triene (containing three double bonds). This diverse unsaturation provides cardanol with a wide range of chemical reactivity and application potential, especially in adjusting resin properties. However, the unsaturated carbon chain in the side group of cardanol also brings certain challenges. Due to its strong lipophilicity, when cardanol is used to synthesize furan resin, it may cause the resin to delaminate during storage and use. Delamination not only affects the uniformity and stability of the resin, but may also cause the strength of the cured resin to decrease, thus limiting the widespread use of cardanol-based furan resin in certain application fields.

[0028] Therefore, in order to meet higher usage requirements, it is necessary to modify cardanol and appropriately increase its polarity and water solubility to ensure the mechanical properties of the resin binder for casting. The cardanol-modified furan resin proposed in this application will be able to effectively enhance its application potential in the field of sand casting. Based on the above situation, this application proposes a modified furan resin for 3D jet printing and a preparation method thereof, wherein the preparation method may include: (1) Cardanol was modified using thiol-functionalized 2-ureido-4-[1H]-pyrimidinone to obtain cardanol derivatives through a thiol-double bond click chemistry reaction.

[0029] like Figure 1Shown is a schematic diagram of the reaction principle of cardanol derivatives.

[0030] (2) reacting a phenol mixture with an aldehyde compound to obtain a cardanol-modified furan resin; the phenol mixture comprises the cardanol derivative and a phenol compound.

[0031] The present application starts from the synthesis of cardanol derivatives, improves the furan resin raw material, prepares cardanol modified furan resin, partially modifies the unsaturated double bonds of cardanol, introduces primitives with strong interface bonding and multivalent interaction, increases the intermolecular force in the resin and the compatibility of the system, thereby improving the impact strength of the furan resin, and at the same time, suppresses the stratification phenomenon during storage and use, and improves storage stability. Then, a cardanol modified furan resin with better performance is obtained, which has good application prospects. In practical applications, in addition to improving the curing speed and strength of the furan resin, it can also improve storage stability and cleanliness, and has excellent application prospects.

[0032] Example 1 1) Synthesis of cardanol derivatives 3.02 g of cardanol, 3.15 g of thiol-functionalized 2-ureido-4-[1H]-pyrimidone and 140 mg of azobisisobutyronitrile were dissolved in 20 mL of dichloromethane and reacted at 80 °C for 8 h under stirring. After the system was cooled, water was added to the reaction system and washed three times. The dichloromethane layer was collected, rotary evaporated and dried. After drying, a powder was obtained, which was the cardanol derivative. 2) Synthesis of cardanol-modified furan resin In a 250ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, add cardanol, 1.5mol cardanol derivative and 0.1mol KOH aqueous solution in sequence, wherein the molar ratio of cardanol to cardanol derivative is n(cardanol):n(cardanol derivative)=1:0.5. Heat to 100°C under stirring, add furfural aqueous solution to the reaction system at a ratio of n(furfural):n(phenols)=1:0.75, and make phenolic compounds and furfural undergo polycondensation reaction. After reflux reaction for 5 hours, the reaction is terminated and cooled to room temperature to obtain a pre-product. The above pre-product, furfuryl alcohol and acidic catalyst are added to the reactor at a mass ratio of 100:200:1, heated to 80°C, reacted for 3 hours, and vacuum dehydrated after the reaction to obtain cardanol modified furan resin.

[0033] Furfural is used to replace formaldehyde, and cardanol is used to replace phenol to produce formaldehyde-free and phenol-free base resins, thereby reducing environmental pollution and harm to the human body.

[0034] Furfuryl alcohol and hydroquinone are added to a reaction kettle, heated and fully mixed to obtain a furfuryl alcohol premix. By premixing furfuryl alcohol with a curing accelerator, it is possible to ensure that when the resin spray comes into contact with the curing agent in the sand layer during the 3D jet printing process, the free furfuryl alcohol is cross-linked with the surface of the sand particles under the action of the curing agent, thereby improving the strength of the sand mold.

[0035] Preparation steps of furan resin: stir and mix the pre-product, furfuryl alcohol premix, cross-linking agent, surfactant and solvent furfuryl alcohol evenly, and then add silane coupling agent to obtain modified furan resin for 3D inkjet printing.

[0036] In the step of preparing the furfuryl alcohol premix, the curing accelerator and furfuryl alcohol are added into the reaction kettle at a weight ratio of 1:6, and stirred at below 70° C. for 2 hours.

[0037] Example 2 1) Synthesis of cardanol derivatives 3.02 g of cardanol, 5.01 g of thiol-functionalized 2-ureido-4-[1H]-pyrimidone, and 140 mg of azobisisobutyronitrile were dissolved in 20 mL of dichloromethane and reacted at 80 °C for 8 h under stirring. After the system was cooled, water was added to the reaction system and washed three times. The dichloromethane layer was collected, rotary evaporated and dried. After drying, the powder was obtained, which was the cardanol derivative. 2) Synthesis of cardanol-modified furan resin In a 250ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, cardanol, cardanol derivatives (1.5mol) and KOH aqueous solution (0.1mol) were added in sequence, wherein the molar ratio of cardanol to cardanol derivatives was n(cardanol):n(cardanol derivative)=1:1. The mixture was heated to 100°C under stirring, and the furfural aqueous solution was added to the reaction system at a ratio of n(furfural):n(phenols)=1.25:1 to allow the phenolic compounds and furfural to undergo polycondensation reaction. After reflux reaction for 5 hours, the reaction was terminated and cooled to room temperature to obtain a pre-product; the pre-product, furfuryl alcohol and acidic catalyst were added to the reactor at a mass ratio of 100:200:1, the temperature was raised to 80°C, the reaction was carried out for 3 hours, and vacuum dehydration was performed after the reaction was completed to obtain a cardanol-modified furan resin.

[0038] Example 3 1) Synthesis of cardanol derivatives 3.02 g of cardanol, 6.31 g of thiol-functionalized 2-ureido-4-[1H]-pyrimidone, and 140 mg of azobisisobutyronitrile were dissolved in 20 mL of dichloromethane and reacted at 70 °C for 8 h under stirring. After the system was cooled, water was added to the reaction system and washed three times. The dichloromethane layer was collected, rotary evaporated and dried. After drying, a powder was obtained, which was the cardanol derivative. 2) Synthesis of cardanol-modified furan resin In a 250ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, cardanol, 1.5mol cardanol derivative and 0.1mol KOH aqueous solution are added in sequence, wherein the molar ratio of cardanol to cardanol derivative is n(cardanol):n(cardanol derivative)=1:1.5. Heat to 100°C under stirring, add furfural aqueous solution to the reaction system at a ratio of n(furfural):n(phenols)=1.5:1, and make phenolic compounds and furfural undergo polycondensation reaction. After reflux reaction for 5 hours, the reaction is terminated and cooled to room temperature to obtain a pre-product; the pre-product, furfuryl alcohol and acidic catalyst are added to the reactor at a mass ratio of 100:200:1, heated to 80°C, reacted for 3 hours, and vacuum dehydrated after the reaction to obtain cardanol modified furan resin.

[0039] Example 4 1) Synthesis of cardanol derivatives 3.02 g of cardanol, 2.74 g of thiol-functionalized 2-ureido-4-[1H]-pyrimidone, and 140 mg of azobisisobutyronitrile were dissolved in 20 mL of dichloromethane and reacted at 70 °C for 6 h under stirring. After the system was cooled, water was added to the reaction system and washed three times. The dichloromethane layer was collected, rotary evaporated and dried. After drying, the powder was obtained, which was the cardanol derivative. 2) Synthesis of cardanol-modified furan resin In a 250ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, cardanol, 1.5mol cardanol derivative and 0.1mol KOH aqueous solution are added in sequence, wherein the molar ratio of cardanol to cardanol derivative is n(cardanol):n(cardanol derivative)=1:0.75. Heat to 100°C under stirring, add furfural aqueous solution to the reaction system at a ratio of n(furfural):n(phenols)=1.5:1, and make phenolic compounds and furfural undergo polycondensation reaction. After reflux reaction for 5 hours, the reaction is terminated and cooled to room temperature to obtain a pre-product; the pre-product, furfuryl alcohol and acid catalyst are added to the reactor at a mass ratio of 100:200:1, heated to 80°C, reacted for 3 hours, and vacuum dehydrated after the reaction to obtain cardanol modified furan resin.

[0040] Example 5 1) Synthesis of cardanol derivatives 3.02 g of cardanol, 5.49 g of thiol-functionalized 2-ureido-4-[1H]-pyrimidone, and 140 mg of azobisisobutyronitrile were dissolved in 20 mL of dichloromethane and reacted at 70 °C for 6 h under stirring. After the system was cooled, water was added to the reaction system and washed three times. The dichloromethane layer was collected, rotary evaporated and dried. After drying, a powder was obtained, which was the cardanol derivative. 2) Synthesis of cardanol-modified furan resin In a 250ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, cardanol, 1.5mol cardanol derivative and 0.1mol KOH aqueous solution are added in sequence, wherein the molar ratio of cardanol to cardanol derivative is n(cardanol):n(cardanol derivative)=1:1.05. Heat to 100°C under stirring, add furfural aqueous solution to the reaction system at a ratio of n(furfural):n(phenols)=1.5:1, and make phenolic compounds and furfural undergo polycondensation reaction. After reflux reaction for 5 hours, the reaction is terminated and cooled to room temperature to obtain a pre-product; the pre-product, furfuryl alcohol and acidic catalyst are added to the reactor at a mass ratio of 100:200:1, heated to 80°C, reacted for 3 hours, and vacuum dehydrated after the reaction to obtain cardanol modified furan resin.

[0041] It should be noted that the reaction container used in the above embodiments can be adjusted according to the amount of each reagent added and the specific application scenario. The embodiment is only an example and does not limit the amount of reagents used in this application.

[0042] In addition, in other embodiments of the present application, the aldehyde compound may also be other types of aldehyde compounds, such as glyoxal and formaldehyde. The alkaline catalyst may be NaOH or ammonia, or a combination of different types of alkaline catalysts. In addition to cardanol, a phenolic compound in the phenolic mixture may also be one or more of phenol, furfuryl alcohol, resorcinol and o-cresol.

[0043] In order to verify the technical effect of this application, the following comparative example is used: Comparative Example 1 In a 250ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, cardanol, 1.5mol cardanol derivative and 0.1mol KOH aqueous solution were added in sequence, wherein the molar ratio of cardanol to cardanol derivative was n(cardanol):n(cardanol derivative)=1:0.5. The mixture was heated to 100°C under stirring, and the furfural aqueous solution was added to the reaction system at a ratio of n(furfural):n(phenols)=1:0.75 to allow the phenolic compound and furfural to undergo polycondensation reaction. After reflux reaction for 5 hours, the reaction was terminated and cooled to room temperature to obtain a first comparative pre-product; the first comparative pre-product, furfuryl alcohol and acidic catalyst were added to the reactor at a mass ratio of 100:200:1, the temperature was raised to 80°C, the reaction was carried out for 3 hours, and vacuum dehydration was performed after the reaction was completed to obtain a first comparative cardanol modified furan resin.

[0044] Comparative Example 2 In a 250 ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, phenol and KOH aqueous solutions were added in a ratio of n(phenol):n(cardanol):n(KOH)=0.5:1:0.1, and the mixture was heated to 80°C with stirring, and then heated to 100°C with stirring. The furfural aqueous solution was added to the reaction system in a ratio of n(furfural):n(phenol)=1:1 to allow phenol and furfural to undergo a polycondensation reaction. After reflux reaction for 5 hours, the reaction was terminated and cooled to room temperature to obtain a first comparative pre-product. The above-mentioned first comparative pre-product, furfuryl alcohol and an acidic catalyst were added to the reactor in a mass ratio of 100:100:1, the temperature was raised to 80°C, the reaction was carried out for 3 hours, and vacuum dehydration was performed after the reaction was completed to obtain a second comparative cardanol-modified furan resin.

[0045] Comparative Example 3 In a 250 ml three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, phenol and KOH aqueous solutions were added in a ratio of n(phenol):n(cardanol):n(KOH)=0.5:1:0.1, and heated to 80°C with stirring, and heated to 100°C with stirring, and furfural aqueous solution was added to the reaction system in a ratio of n(furfural):n(phenol)=1:1.25 to allow phenol and furfural to undergo a polycondensation reaction. After reflux reaction for 5 hours, the reaction was terminated and cooled to room temperature to obtain a third comparative pre-product; the third comparative pre-product, furfuryl alcohol and an acidic catalyst were added to the reactor in a mass ratio of 100:150:1, the temperature was raised to 80°C, the reaction was carried out for 3 hours, and vacuum dehydration was performed after the reaction was completed to obtain a third comparative cardanol-modified furan resin.

[0046] Examples 1-3 of the present application and ordinary furan resin comparative examples 1-3 were used as adhesives to perform physical and chemical characterization, storage stability and mechanical tests of sand casting products. Raw sand (40 / 70 mesh standard Dalin new silica sand) was used for sand casting in Examples 1-3 and Comparative Examples 1-3. The liquid-to-material ratio was 1.2% (accounting for the proportion of raw sand) of the resin, 0.4% (accounting for the proportion of raw sand) of the curing agent benzenesulfonic acid, and the curing time was 24h. The tensile strength was tested with the cured sand mold 8-shaped sample. The specific performance indicators are shown in Table 1.

[0047] Table 1 Test performance table of furan resin of Examples 1-3 and Comparative Examples 1-3

[0048] As shown in Table 1, the cardanol derivative modified furan resin obtained in the present application has a lower viscosity than the basic comparative example, and the strength of the molding sand after curing is higher than that of the ordinary furan resin, indicating that its curing speed and strength are improved. In addition, the long-term storage stability of the cardanol derivative modified furan resin is significantly improved compared with the traditional furan resin.

[0049] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a modified furan resin for 3D jet printing, characterized in that: include: Cardanol was modified with thiol-functionalized 2-ureido-4-[1H]-pyrimidinone to obtain cardanol derivatives through thiol-double bond click chemistry reaction; A phenolic mixture and an aldehyde compound are reacted to obtain a cardanol-modified furan resin; the phenolic mixture comprises the cardanol derivative and a phenolic compound.

2. A method for preparing a modified furan resin for 3D jet printing according to claim 1, characterized in that: The step of reacting the phenolic mixture with the aldehyde compound comprises: allowing a phenolic mixture and an aldehyde compound to react in urea and an alkaline catalyst to obtain a pre-product; The pre-product is reacted with an alcohol compound in the presence of an acidic catalyst to obtain a cardanol-modified furan resin.

3. A method for preparing a modified furan resin for 3D jet printing according to claim 2, characterized in that: The step of reacting the phenolic mixture with the aldehyde compound comprises: Mixing cardanol, cardanol derivatives, aldehyde compounds, urea and an alkaline catalyst, heating the mixture under a pH value of 8 to 9 for reflux reaction, and cooling the mixture to room temperature after the reaction is completed to obtain a pre-product; The pre-product, furfuryl alcohol and an acid catalyst are mixed, reacted after heating, and dehydrated after the reaction is completed to obtain cardanol-modified furan resin.

4. A method for preparing a modified furan resin for 3D jet printing according to claim 2, characterized in that: The phenolic compound is cardanol, the aldehyde compound is furfural, and the alcohol compound is furfuryl alcohol.

5. A method for preparing a modified furan resin for 3D jet printing according to claim 4, characterized in that: The step of reacting the phenolic mixture with the aldehyde compound comprises: Cardanol, cardanol derivatives, furfural, urea and alkaline catalyst are placed in a reaction kettle at a molar ratio of 1:0.5:2:0.2:0.1, the pH value is controlled at 8-9, the temperature is raised to 100 °C, refluxed for 5 hours, and then cooled to room temperature to obtain a pre-product; The pre-product, furfuryl alcohol and acid catalyst were added into the reactor in a mass ratio of 100:200:1, the temperature was raised to 80°C, the reaction was carried out for 3 hours, and vacuum dehydration was carried out after the reaction was completed to obtain cardanol-modified furan resin.

6. A method for preparing a modified furan resin for 3D jet printing according to claim 4, characterized in that: The molar ratio of the cardanol to the cardanol derivative is 1:(0.5-1.5).

7. A method for preparing a modified furan resin for 3D jet printing according to claim 4, characterized in that: The mass ratio of the cardanol, the cardanol derivative, furfural, urea, the alkaline catalyst and furfuryl alcohol is 100: (50-150): (200-350): 20: (6-9): (40-75).

8. A method for preparing a modified furan resin for 3D jet printing according to any one of claims 5 to 7, characterized in that: The method of modifying cardanol using thiol-functionalized 2-ureido-4-[1H]-pyrimidinone comprises: Cardanol and thiol-functionalized 2-ureido-4-[1H]-pyrimidone were dissolved in dichloromethane, and azobisisobutyronitrile was added dropwise as an initiator. The mixture was refluxed at 80 °C for 8 h under stirring. After cooling, add water, extract and wash, and collect the dichloromethane layer; The collected dichloromethane layer is subjected to rotary evaporation, and after drying, a powder is obtained, which is a cardanol derivative.

9. A method for preparing a modified furan resin for 3D jet printing according to claim 8, characterized in that: The structure of the cardanol derivative comprises: 。 10. A modified furan resin for 3D jet printing, characterized in that: The modified furan resin for 3D jet printing is obtained by the preparation method of any one of claims 1 to 9.

Images