Formaldehyde-free furan resin based on molecular sieve catalyst and preparation method thereof

Abstract

The present invention discloses a formaldehyde-free furan resin based on a molecular sieve catalyst and a preparation method thereof. The present invention uses glycerol as a substitute for formaldehyde and utilizes a molecular sieve as a catalyst. The entire reaction system does not involve formaldehyde, so there is no formaldehyde in the reactant system, and the product is green and environmentally friendly. Since the resin of the present invention does not add a formaldehyde aqueous solution, it has low moisture content, high strength, and strong adaptability. In the present invention, the molecular sieve can effectively catalyze the curing reaction during the curing process, and the molecular sieve can act as a filler trial version during volume shrinkage, so that the curing reaction is more complete, and the resin film between the resin sands is fuller and has better strength.

Description

Technical Field

[0001] The invention belongs to the technical field of resin synthesis, and particularly relates to an aldehyde-free furan resin based on a molecular sieve catalyst and a preparation method thereof. Background Art

[0002] Self-hardening resin binders have been gradually introduced into the foundry industry since the 1960s, and have been increasingly valued by various countries. my country began to research and develop a complete set of processes for furan resin sand in the late 1970s and early 1980s. The former Ministry of Machinery Industry listed furan resin sand as a key promotion project for use in the foundry industry in 1991. After more than 30 years of development, furan resin sand has become a widely used and mature process in the foundry industry.

[0003] The core of furan resin sand process is the synthesis process of furan resin. After more than 30 years of research and development, the quality of furan resin has been greatly improved compared with before, the formaldehyde content in the resin has been greatly reduced, the strength of the resin has been greatly improved, and the amount of resin added has also been greatly reduced. However, the lack of formaldehyde in the existing furan resin process makes it difficult to have good strength, which affects the use of the resin. It is very difficult to find a suitable formaldehyde substitute. Polyol compounds such as xylitol, glycerol, and sorbitol were once the choice of this type of process, but the reactivity of polyol compounds is difficult to compare with formaldehyde compounds, and the obtained furan resin is difficult to compare with the furan resin made of formaldehyde in terms of strength. Summary of the invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a green and environmentally friendly high-strength formaldehyde-free furan resin based on a molecular sieve catalyst and a preparation method thereof.

[0005] Technical solution: In order to solve the above technical problems, the present invention provides a formaldehyde-free furan resin based on a molecular sieve catalyst, which is made of the following components by weight percentage: 0.1-1.5% molecular sieve, 10-30% glycerol, 3-20% urea, 30-80% furfuryl alcohol, 5-18% methanol, and 0.2-0.5% silane coupling agent.

[0006] Preferably, the composition comprises the following components by weight: 1.5% molecular sieve, 10% glycerol, 3% urea, 80% furfuryl alcohol, 5% methanol and 0.5% silane coupling agent.

[0007] Preferably, the molecular sieve has a silicon-to-aluminum ratio of greater than 25 and a particle size distribution of 5-10 microns.

[0008] Preferably, the silane coupling agent is N-(β-aminoethyl)-γ-aminopropylmethyl-dimethoxysilane (KH602).

[0009] Preferably, the furfuryl alcohol is added in two times, with 10-40% added in the first time and 20-40% added in the second time.

[0010] The present invention also includes a method for preparing the aldehyde-free furan resin based on a molecular sieve catalyst, comprising the following steps:

[0011] 1) molecular sieve, glycerol, urea and furfuryl alcohol are put into a reaction kettle together, potassium hydroxide solution is added to adjust the pH to 11-13, the mixture is heated to 110-130° C., and the mixture is reacted for 1-4 hours to obtain a mixed solution;

[0012] 2) Then, furfuryl alcohol is added to the mixed solution, and hydrochloric acid is added to adjust the pH to 2-3, and the mixture is heated to 90-110° C., reacted for 1-4 hours, cooled to 60° C., and methanol and a silane coupling agent are added to obtain a finished furan resin.

[0013] Wherein, the amount of furfuryl alcohol added in step 1) is 10-40%, and the amount of furfural added in step 2) is 20-40%.

[0014] Reaction mechanism: The present invention uses a nano-scale molecular sieve compound with a special composition as a catalyst, and uses the catalyst to catalyze the dehydration reaction of urea and glycerol to form a polymer with a certain molecular segment, and then copolymerizes with furfuryl alcohol under acidic conditions to finally obtain a finished furan resin. The molecular sieve used in the present invention has a silicon-aluminum ratio of more than 25. This type of molecular sieve can be used as a Lewis acid and can well catalyze the dehydration reaction.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0016] 1. The present invention uses glycerol as a substitute for formaldehyde and utilizes molecular sieves as catalysts. No formaldehyde is involved in the entire reaction system, so there is no formaldehyde in the reactant system, and the product is green and environmentally friendly.

[0017] 2. Since no formaldehyde solution is added to the resin of the present invention, the resin has low moisture content, high strength and strong adaptability.

[0018] 3. The molecular sieve used in the present invention can effectively catalyze the curing reaction during the curing process, and the molecular sieve can serve as a filler trial version during volume shrinkage, so that the curing reaction is more complete, the resin film between the resin sand is fuller, and the strength is better. DETAILED DESCRIPTION

[0019] The molecular sieve in the present invention has a silicon-aluminum ratio of more than 25 and a particle size distribution of 5-10 microns, which was purchased from Zibo Runxin Chemical Technology Co., Ltd. and has a product number of ZSM-5. The silane coupling agent was purchased from Hangzhou Jessica Chemical Co., Ltd. and has a product number of KH602.

[0020] Example 1

[0021] Put 1.5% molecular sieve, 10% glycerol, 3% urea, and 40% furfuryl alcohol into a reactor, add potassium hydroxide solution to adjust the pH to 11, heat to 110°C, and react for 2 hours. Then add 40% furfuryl alcohol, add hydrochloric acid to adjust the pH to 3, heat to 100°C, react for 1 hour, cool to 60°C, add 5% methanol and 0.5% silane coupling agent KH602.

[0022] Example 2

[0023] 0.1% molecular sieve, 12% glycerol, 5% urea, and 35% furfuryl alcohol were put into the reactor, potassium hydroxide solution was added to adjust the pH to 12, heated to 120°C, and reacted for 1 hour. Then 35% furfuryl alcohol was added, hydrochloric acid was added to adjust the pH to 2, heated to 110°C, reacted for 2 hours, cooled to 60°C, and 12.4% methanol and 0.5% silane coupling agent KH602 were added.

[0024] Example 3

[0025] 0.5% molecular sieve, 20% glycerol, 10% urea, and 30% furfuryl alcohol were put into a reactor, potassium hydroxide solution was added to adjust the pH to 13, heated to 130°C, and reacted for 3 hours. Then 30% furfuryl alcohol was added, hydrochloric acid was added to adjust the pH to 4, heated to 90°C, reacted for 4 hours, cooled to 60°C, and 9% methanol and 0.5% silane coupling agent KH602 were added.

[0026] Example 4

[0027] Put 1% molecular sieve, 25% glycerol, 10% urea, and 30% furfuryl alcohol into a reactor, add potassium hydroxide solution to adjust the pH to 12, heat to 120°C, and react for 2 hours. Then add 30% furfuryl alcohol, add hydrochloric acid to adjust the pH to 2.5, heat to 110°C, react for 4 hours, cool to 60°C, add 3.5% methanol and 0.5% silane coupling agent KH602.

[0028] Example 5

[0029] 1.5% molecular sieve, 22% glycerol, 10% urea, and 30% furfuryl alcohol were put into the reactor, potassium hydroxide solution was added to adjust the pH to 11.5, heated to 115°C, and reacted for 4 hours. Then 30% furfuryl alcohol was added, hydrochloric acid was added to adjust the pH to 2.5, heated to 105°C, reacted for 1 hour, cooled to 60°C, and 6% methanol and 0.5% silane coupling agent KH602 were added.

[0030] Example 6

[0031] 0.7% molecular sieve, 28% glycerol, 15% urea, and 20% furfuryl alcohol were put into the reactor, potassium hydroxide solution was added to adjust the pH to 12, heated to 110°C, and reacted for 2 hours. Then 25% furfuryl alcohol was added, hydrochloric acid was added to adjust the pH to 2, heated to 115°C, reacted for 1 hour, cooled to 60°C, and 11% methanol and 0.3% silane coupling agent KH602 were added.

[0032] Example 7

[0033] Put 1.5% molecular sieve, 30% glycerol, 20% urea and 10% furfuryl alcohol into the reactor, add potassium hydroxide solution to adjust the pH to 13, heat to 130℃ and react for 3 hours. Then add 20% furfuryl alcohol, add hydrochloric acid to adjust the pH to 3, heat to 110℃, react for 4 hours, cool to 60℃, add 18% methanol and 0.5% silane coupling agent KH602.

[0034] Comparative Example 1

[0035] 6% urea was added to 22% of 37% formaldehyde aqueous solution, the pH was adjusted to 9, and the reaction was carried out at 90°C for 1 hour. Then 60% furfuryl alcohol was added, the pH was adjusted to 4, and the reaction was carried out at 100°C for 1 hour. Finally, 11.5% methanol and 0.5% silane coupling agent KH602 were added.

[0036] Comparative Example 2

[0037] 10% urea was added to 35% of 37% formaldehyde aqueous solution, the pH was adjusted to 8.8, and the reaction was carried out at 90°C for 1.5 hours. Then 50% furfuryl alcohol was added, the pH was adjusted to 4.2, and the reaction was carried out at 100°C for 1 hour. Finally, 4.5% methanol and 0.5% silane coupling agent KH602 were added.

[0038] Comparative Example 3

[0039] 15% urea was added to 45% of a 37% formaldehyde aqueous solution, the pH was adjusted to 8.8, and the mixture was reacted at 90°C for 1.5 hours. Then 30% furfuryl alcohol was added, the pH was adjusted to 4.2, and the mixture was reacted at 100°C for 1 hour. Finally, 9.5% methanol and 0.5% silane coupling agent KH602 were added.

[0040] According to the requirements of JB / T 7526-2008 standard, the furfuryl alcohol content, free formaldehyde and tensile strength of Examples 1-7 and Comparative Examples 1-3 were tested. The test data are shown in Table 1:

[0041] Table 1

[0042] Furfuryl alcohol content, % Free formaldehyde, % Tensile strength, MPa Example 1 81.14 0 2.02 Example 2 69.67 0 1.91 Example 3 60.12 0 1.59 Example 4 59.76 0 1.68 Example 5 59.70 0 1.55 Example 6 45.76 0 1.38 Example 7 29.79 0 1.02 Comparative Example 1 61.54 0.29 1.57 Comparative Example 2 49.75 0.21 1.35 Comparative Example 3 29.85 0.17 1.04

[0043] Comparative Examples 1-3 are processes of existing formaldehyde formulas. As can be seen from Table 1, the free formaldehyde content of the resin produced by the present invention is all 0. And under the condition of the same furfuryl alcohol usage, the furan resin prepared by the examples of the present invention has higher strength than that prepared by the comparative examples.

Claims

1. A formaldehyde-free furan resin based on a molecular sieve catalyst, characterized in that: The resin comprises the following components by weight percentage: 0.1-1.5% molecular sieve, 10-30% glycerol, 3-20% urea, 30-80% furfuryl alcohol, 5-18% methanol, and 0.2-0.5% silane coupling agent. The method for preparing the formaldehyde-free furan resin based on the molecular sieve catalyst comprises the following steps: 1) Place molecular sieve, glycerol, urea and furfuryl alcohol into a reactor, add potassium hydroxide solution to adjust the pH to 11-13, heat to 110-130°C, and react for 1-4 hours to obtain a mixed solution; 2) Then add furfuryl alcohol to the mixed solution, add hydrochloric acid to adjust the pH to 2-3, heat to 90-110°C, react for 1-4 hours, cool to 60°C, add methanol and silane coupling agent to obtain the finished furan resin.

2. The formaldehyde-free furan resin based on molecular sieve catalyst according to claim 1, characterized in that: The composition includes the following components by weight: 1.5% molecular sieve, 10% glycerol, 3% urea, 80% furfuryl alcohol, 5% methanol and 0.5% silane coupling agent.

3. The formaldehyde-free furan resin based on molecular sieve catalyst according to claim 1, characterized in that: The molecular sieve has a silicon-to-aluminum ratio of more than 25 and a particle size distribution of 5-10 microns.

4. The formaldehyde-free furan resin based on molecular sieve catalyst according to claim 1, characterized in that: The silane coupling agent is N-(β-aminoethyl)-γ-aminopropylmethyl-dimethoxysilane.

5. The formaldehyde-free furan resin based on molecular sieve catalyst according to claim 1, characterized in that: The furfuryl alcohol is added in two times, 10-40% is added in the first time, and 20-40% is added in the second time.

6. The method for preparing the formaldehyde-free furan resin based on a molecular sieve catalyst according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) Place molecular sieve, glycerol, urea and furfuryl alcohol into a reactor, add potassium hydroxide solution to adjust the pH to 11-13, heat to 110-130°C, and react for 1-4 hours to obtain a mixed solution; 2) Then add furfuryl alcohol to the mixed solution, add hydrochloric acid to adjust the pH to 2-3, heat to 90-110°C, react for 1-4 hours, cool to 60°C, add methanol and silane coupling agent to obtain the finished furan resin.

7. The method for preparing the formaldehyde-free furan resin based on the molecular sieve catalyst according to claim 6, characterized in that: The amount of furfuryl alcohol added in step 1) is 10-40%, and the amount of furfural added in step 2) is 20-40%.