Process for the preparation of a hydrogenated aldehyde-ketone resin free of free formaldehyde

Abstract

The application discloses a preparation method of hydrogenated aldehyde ketone resin without free formaldehyde, belongs to the technical field of aldehyde ketone resin synthesis, and aims to solve the technical problems of high free formaldehyde content, and further improved hydroxyl value stability and transparency in the hydrogenated aldehyde ketone resin in the prior art, and specifically comprises the following steps: under the protection of an inert gas atmosphere, phenylacetone, polyformaldehyde and a solvent are mixed and stirred, the reaction system is heated to 60-75 DEG C, and an inorganic alkali is added into the reaction system. The application is characterized in that the basic aldehyde ketone resin solution prepared by condensation of polyformaldehyde and phenylacetone in a water-free environment with a nickel catalyst is catalytically hydrogenated, not only the hydrogenated aldehyde ketone resin with stable hydroxyl value and extremely low colority is effectively obtained, but also the free formaldehyde content in the hydrogenated aldehyde ketone resin is effectively reduced, and the wide applicability of the hydrogenated aldehyde ketone resin in high-end coatings, adhesives and electronic materials is improved.

Description

Technical Field

[0001] This invention relates to the field of aldehyde and ketone resin synthesis technology, and specifically to a method for preparing hydrogenated aldehyde and ketone resin that does not contain free formaldehyde. Background Technology

[0002] Aldehyde-ketone resins are a class of thermoplastic resins produced by the condensation of aromatic ketone compounds with aldehydes such as formaldehyde under acidic or alkaline conditions. They possess excellent transparency, hardness, gloss, and weather resistance, and are widely used in coatings, inks, adhesives, leather treatment agents, and electronic materials. Further improvements in the color stability, yellowing resistance, solubility, and reactivity of aldehyde-ketone resins can be achieved by hydrogenating the carbonyl groups in the resin, converting them into hydroxyl groups.

[0003] Currently, aldehyde-ketone resins typically use formaldehyde aqueous solution as the aldehyde source. However, this system has a high water content and is prone to the Cannizaro reaction and unnecessary side condensation reactions under alkaline conditions, generating formate, conjugated structures, and polymers. This not only increases the resin color but also significantly increases the free formaldehyde content, making it difficult for the final product and downstream materials to meet the requirements for low odor and low VOC. Furthermore, in traditional condensation reactions, formaldehyde participates in the reaction at a high instantaneous concentration, making it difficult to achieve uniform supply. This makes it easy for the condensation process to be difficult to control, resulting in a wide resin structure distribution and poor product stability.

[0004] On the other hand, traditional hydrogenation processes often use Raney nickel as a catalyst, but it has poor selectivity for aromatic ring hydrogenation, is prone to over-hydrogenation or skeleton destruction, leading to increased resin color and even structural degradation. It also has insufficient ability to remove trace amounts of formaldehyde, resulting in a high free formaldehyde content in the hydrogenated resin. Consequently, the free formaldehyde content in hydrogenated aldehyde-ketone resins is high, and the stability and transparency of hydroxyl value need further improvement.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing hydrogenated aldehyde-ketone resin without free formaldehyde, which solves the technical problems of high free formaldehyde content, hydroxyl value stability and transparency in existing hydrogenated aldehyde-ketone resins.

[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing a hydrogenated aldehyde-ketone resin that does not contain free formaldehyde, comprising the following steps:

[0008] S1. Under an inert gas atmosphere, acetophenone, paraformaldehyde and solvent are mixed and stirred. The reaction system is heated to 60-75℃. An inorganic base is added to the reaction system and the reaction is kept at the temperature for 4-6 hours to obtain an aldehyde-ketone resin solution.

[0009] S2. The aldehyde-ketone resin solution and nickel catalyst are added to a high-pressure reactor for high-pressure hydrogenation to obtain hydrogenated aldehyde-ketone resin. The nickel catalyst comprises an active metal composed of a silicon-aluminum-based support and nickel and copper. The mass fraction of nickel is 55-60%, and the molar ratio of nickel to copper is 10-15:1.

[0010] Furthermore, in step S1, the weight ratio of acetophenone to paraformaldehyde is 5-7:1, the weight ratio of acetophenone to inorganic base is 80-120:1, the inorganic base is any one of potassium hydroxide, sodium hydroxide, and calcium hydroxide, the weight ratio of solvent to acetophenone is 1:3-4, and the solvent is any one of methanol, ethanol, isopropanol, and isobutanol.

[0011] Further, in step S2, the high-pressure hydrogenation operation includes: adding the aldehyde-ketone resin solution and nickel catalyst into a high-pressure reactor and mixing and stirring; after sealing the high-pressure reactor, first replacing the air in the high-pressure reactor with inert gas 3 times, then replacing the inert gas in the high-pressure reactor with hydrogen 6 times; setting the heating temperature of the high-pressure reactor to 130-140℃; continuously introducing hydrogen gas at a pressure of 4-5MPa for the hydrogenation reaction; after the temperature of the high-pressure reactor stabilizes, maintaining the hydrogenation reaction for 13-15 hours; and then post-processing to obtain hydrogenated aldehyde-ketone resin.

[0012] Further, the weight ratio of the nickel catalyst to the acetophenone used in step S1 is 1:150-200. The post-treatment includes: after the reaction is complete, stopping the hydrogen supply, cooling and depressurizing the high-pressure reactor to room temperature and atmospheric pressure, filtering, adjusting the pH of the filtrate to 7 with glacial acetic acid and transferring it to the high-pressure reactor, depressurizing the high-pressure reactor to -0.1 MPa, gradually heating the high-pressure reactor to 70-80°C, removing low-boiling substances under reduced pressure, adding toluene to the high-pressure reactor, stirring to dissolve, adding deionized water to the high-pressure reactor, stirring and dispersing for 20-30 minutes, allowing it to stand and separate, washing the organic phase twice with deionized water and transferring it to another cleaned high-pressure reactor, depressurizing the high-pressure reactor to -0.1 MPa, then gradually heating to 130-150°C, removing low-boiling substances under reduced pressure to obtain hydrogenated aldehyde-ketone resin.

[0013] Furthermore, the nickel catalyst is obtained by the following steps:

[0014] A1. Add the active metal salt to deionized water and mix. Stir at room temperature until the system dissolves. Add the silica-alumina-based support to the reaction system. Add ammonia to the reaction system and adjust the pH of the system to 5-6. Impregnate for 30-50 min. Add ammonia to the reaction system and adjust the pH of the system to 9-10. Let it stand for aging for 8-10 h. After post-treatment, obtain the nickel catalyst precursor.

[0015] A2. The nickel catalyst precursor is placed in a tube furnace for aerobic roasting, and then reduced roasting is carried out in a reducing gas atmosphere to obtain the nickel catalyst.

[0016] Further, in step A1, the ratio of the active metal salt to deionized water is 1g:10mL, the active metal salt is composed of nickel nitrate and copper nitrate in a molar ratio of 10-15:1, the mass fraction of the ammonia water is 20%, and the post-treatment includes: after the reaction is completed, filtration is performed, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 90-100℃ and dried to constant weight to obtain a nickel catalyst precursor with a nickel content of 55-60%.

[0017] Furthermore, in step A2, the aerobic roasting temperature is 360-400℃, the roasting time is 3-4h, and the roasting atmosphere is air; the reduction roasting temperature is 380-420℃, the roasting time is 4-5h, and the roasting atmosphere is a mixture of hydrogen and nitrogen in a volume ratio of 1:10.

[0018] Furthermore, the silicon-aluminum based carrier is obtained by the following steps:

[0019] B1. Add sodium silicate and aluminum nitrate to deionized water and mix. Stir at room temperature until the system is dissolved. Add polyethylene glycol to the reaction system and stir to disperse for 20-30 minutes. Add alkaline solution to the reaction system to adjust the pH of the system to 8-9. Age at room temperature for 4-6 hours. After post-treatment, obtain the silica-alumina-based support precursor.

[0020] B2. The silicon-aluminum based carrier precursor is placed in a muffle furnace for calcination and then pulverized and passed through an 80-mesh sieve to obtain the silicon-aluminum based carrier.

[0021] Further, in step B1, the ratio of sodium silicate, aluminum nitrate, polyethylene glycol, and deionized water is 70-80g:30-35g:10g:800mL, the alkaline solution is 20wt% ammonia water, and the post-treatment includes: after the reaction is complete, filtration is performed, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 90-100℃ and dried to constant weight to obtain the silica-alumina-based carrier precursor.

[0022] Furthermore, in step B2, the aerobic roasting temperature of the muffle furnace is 560-620℃, the time is 4-5 hours, and the atmosphere is air.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention uses paraformaldehyde instead of formaldehyde solution, eliminating the introduction of large amounts of water into the system, avoiding water-involved Cannizaro reactions and unnecessary condensation side reactions, and reducing the formation of chromophores and polymeric byproducts. Simultaneously, paraformaldehyde releases monomeric formaldehyde slowly through pyrolysis, making the acetal / ketal reaction process more controllable, preventing rapid formaldehyde accumulation in the system, and improving the consistency of the condensation structure. In the subsequent hydrogenation process, the catalytic system with Ni-Cu as the active catalytic site works synergistically with high-pressure hydrogen, allowing residual trace amounts of formaldehyde to be further hydrogenated or participate in condensation conversion. After vacuum purification, the free formaldehyde content in the hydrogenated aldehyde-ketone resin is reduced to an ultra-low level that is difficult to achieve with traditional formaldehyde solution systems. This not only significantly improves the material's safety and environmental properties but also makes the resin more widely applicable in high-end coatings, adhesives, and electronic materials.

[0025] 2. This invention also employs the co-precipitation of sodium silicate and aluminum nitrate under weakly alkaline conditions to prepare a silica-alumina-based support, and introduces polyethylene glycol to form a uniform mesoporous structure. This allows the silica-alumina-based support to possess both moderately acidic sites and a large specific surface area, enabling Ni and Cu to be highly dispersed and firmly anchored during subsequent precipitation and deposition. Further, through high-temperature calcination and mild reduction under dilute hydrogen conditions, the metal nanoparticles remain stable and are difficult to sinter. The introduction of Cu weakens the adsorption capacity of Ni on the π bonds of aromatic rings, significantly reducing the catalyst's tendency to hydrogenate aromatic rings, while its adsorption and activation capacity for carbonyl groups remains unaffected. Under alkaline hydrogenation conditions, carbonyl groups are more easily activated by the metal center, while the hydrogenation kinetics of aromatic rings are further suppressed, avoiding damage to the aromatic ring structure during hydrogenation and improving the final resin's high transparency and excellent mechanical and optical properties.

[0026] 3. This invention also retains the alkaline environment formed during the condensation stage in the hydrogenation process, making it easier for the carbonyl group to form an alkanoic anion intermediate during hydrogenation. This accelerates the formation of alcohol hydroxyl groups on the carbonyl carbon during carbonyl hydrogenation, improving hydrogenation efficiency and thoroughness. Under the synergistic catalysis of Ni and Cu, the high-pressure hydrogen gas causes the carbonyl group to be rapidly reduced, while the aromatic ring maintains a stable structure due to the inhibition of kinetics. This ensures that the resin has a high and stable hydroxyl value. After hydrogenation, the resin is adjusted to neutral by glacial acetic acid, which can effectively terminate the alkaline catalytic side reaction and avoid yellowing, viscosity increase or molecular structure rearrangement during storage, significantly improving the long-term stability of the resin. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The infrared spectrum of the aldehyde-ketone resin prepared in Example 3 of this invention;

[0029] Figure 2 The infrared spectrum of the hydrogenated aldehyde-ketone resin prepared in Example 6 of this invention;

[0030] Figure 3 The infrared spectrum of the hydrogenated aldehyde-ketone resin prepared in Comparative Example 5 of this invention is shown. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a method for preparing a nickel catalyst, including the following steps:

[0034] Step 1: Preparation of silicon-aluminum based carrier

[0035] Weigh out 70g of sodium silicate, 30g of aluminum nitrate, and 800mL of deionized water and add them to a reaction flask. Stir at room temperature until the system is dissolved. Add 10g of polyethylene glycol to the reaction flask and stir to disperse for 20min. Add 20wt% ammonia to the reaction flask to adjust the pH of the system to 8. Age at room temperature for 4h. Filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 90℃ and dry it to constant weight to obtain the silica-alumina-based support precursor.

[0036] The silicon-aluminum-based carrier precursor was placed in a muffle furnace at 560℃ and calcined in air for 4 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature. The precursor was then pulverized and passed through an 80-mesh sieve to obtain the silicon-aluminum-based carrier.

[0037] Step 2: Preparation of nickel catalyst precursor

[0038] Weigh out 18.3 g of nickel nitrate, 1.88 g of copper nitrate, and 202 mL of deionized water into a reaction flask. Stir at room temperature until the system dissolves. Add 11 g of silica-alumina-based support to the reaction flask and 20 wt% ammonia water to adjust the pH of the system to 5. Soak for 30 min. Add another 20 wt% ammonia water to the reaction flask and adjust the pH of the system to 9. Let stand for 8 h for aging. Filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 90 °C and dry it to constant weight to obtain the nickel catalyst precursor.

[0039] Step 3: Preparation of nickel catalyst

[0040] Hydrogen and nitrogen are mixed at a volume ratio of 1:10 to obtain a mixed gas.

[0041] The nickel catalyst precursor was placed in a tube furnace, and the temperature of the tube furnace was raised to 360°C in an air atmosphere and calcined for 3 hours. Nitrogen gas was then introduced into the reaction system to replace the air in the tube furnace. Then, a mixed gas was introduced into the tube furnace, and the temperature of the tube furnace was raised to 380°C and calcined for 4 hours. The tube furnace was then allowed to cool naturally to room temperature, and the material was discharged. The material was sealed and kept under argon protection to obtain the nickel catalyst.

[0042] Example 2

[0043] This embodiment provides a method for preparing a nickel catalyst, including the following steps:

[0044] Step 1: Preparation of silicon-aluminum based carrier

[0045] Weigh out 75g of sodium silicate, 33g of aluminum nitrate, and 800mL of deionized water and add them to a reaction flask. Stir at room temperature until the system dissolves. Add 10g of polyethylene glycol to the reaction flask and stir to disperse for 25min. Add 20wt% ammonia to the reaction flask to adjust the pH of the system to 8.5. Age at room temperature for 5h. Filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 95℃ and dry it to constant weight to obtain the silica-alumina-based support precursor.

[0046] The silicon-aluminum-based carrier precursor was placed in a muffle furnace at 590℃ and calcined in air for 4.5 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature. The precursor was then pulverized and passed through an 80-mesh sieve to obtain the silicon-aluminum-based carrier.

[0047] Step 2: Preparation of nickel catalyst precursor

[0048] Weigh out: 22.9 g of nickel nitrate, 1.88 g of copper nitrate, and 248 mL of deionized water into a reaction flask. Stir at room temperature until the system dissolves. Add 13.5 g of silica-alumina-based support to the reaction flask. Add 20 wt% ammonia water to the reaction flask to adjust the pH of the system to 5.5. Soak for 40 min. Add 20 wt% ammonia water to the reaction flask to adjust the pH of the system to 9.5. Let stand for 9 h for aging. Filter. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 95 ℃ and dry it to constant weight to obtain the nickel catalyst precursor.

[0049] Step 3: Preparation of nickel catalyst

[0050] Hydrogen and nitrogen are mixed at a volume ratio of 1:10 to obtain a mixed gas.

[0051] The nickel catalyst precursor was placed in a tube furnace, and the temperature of the tube furnace was raised to 380°C in an air atmosphere and calcined at that temperature for 3.5 hours. Nitrogen gas was then introduced into the reaction system to replace the air in the tube furnace. Then, a mixed gas was introduced into the tube furnace, and the temperature of the tube furnace was raised to 400°C and calcined at that temperature for 4.5 hours. The tube furnace was then allowed to cool naturally to room temperature, and the material was discharged. The material was sealed and kept under argon protection to obtain the nickel catalyst.

[0052] Example 3

[0053] This embodiment provides a method for preparing a nickel catalyst, including the following steps:

[0054] Step 1: Preparation of silicon-aluminum based carrier

[0055] Weigh out 80g of sodium silicate, 35g of aluminum nitrate, and 800mL of deionized water and add them to a reaction flask. Stir at room temperature until the system is dissolved. Add 10g of polyethylene glycol to the reaction flask and stir to disperse for 30min. Add 20wt% ammonia water to the reaction flask to adjust the pH of the system to 9. Age at room temperature for 6h. Filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 100℃ and dry it to constant weight to obtain the silica-alumina-based support precursor.

[0056] The silicon-aluminum-based carrier precursor was placed in a muffle furnace at 620℃ and calcined in air for 5 hours. After calcination, the muffle furnace was allowed to cool naturally to room temperature. The precursor was then pulverized and passed through an 80-mesh sieve to obtain the silicon-aluminum-based carrier.

[0057] Step 2: Preparation of nickel catalyst precursor

[0058] Weigh out: 27.4 g of nickel nitrate, 1.88 g of copper nitrate, and 293 mL of deionized water into a reaction flask. Stir at room temperature until the system dissolves. Add 16 g of silica-alumina-based support to the reaction flask. Add 20 wt% ammonia water to the reaction flask to adjust the pH of the system to 6. Soak for 50 min. Add 20 wt% ammonia water to the reaction flask to adjust the pH of the system to 10. Let stand for aging for 10 h. Filter. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 100 °C and dry it to constant weight to obtain the nickel catalyst precursor.

[0059] Step 3: Preparation of nickel catalyst

[0060] Hydrogen and nitrogen are mixed at a volume ratio of 1:10 to obtain a mixed gas.

[0061] The nickel catalyst precursor was placed in a tube furnace, and the temperature of the tube furnace was raised to 400°C in an air atmosphere and calcined for 4 hours. Nitrogen gas was then introduced into the reaction system to replace the air in the tube furnace. Then, a mixed gas was introduced into the tube furnace, and the temperature of the tube furnace was raised to 420°C and calcined for 5 hours. The tube furnace was then allowed to cool naturally to room temperature, and the material was discharged. The material was sealed and kept under argon protection to obtain the nickel catalyst.

[0062] Example 4

[0063] This embodiment provides a method for preparing a hydrogenated aldehyde-ketone resin that does not contain free formaldehyde, including the following steps:

[0064] Step I: Preparation of aldehyde-ketone resin solution

[0065] Weigh out 50g of acetophenone, 10g of paraformaldehyde and 180mL of ethanol and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the reaction flask to 60℃. Add 0.63g of potassium hydroxide to the reaction flask and keep the mixture at this temperature for 4 hours to obtain an aldehyde-ketone resin solution.

[0066] Step II: Preparation of hydrogenated aldehyde-ketone resin

[0067] The aldehyde-ketone resin solution prepared in step I was transferred to a high-pressure reactor and stirred. Then, 0.33 g of the nickel catalyst prepared in Example 1 was added to the high-pressure reactor. After the high-pressure reactor was sealed, the air in the reactor was first replaced with nitrogen three times, and then the nitrogen in the reactor was replaced with hydrogen six times. The heating temperature of the high-pressure reactor was set to 130°C, and hydrogen gas at a pressure of 4 MPa was continuously introduced to carry out the hydrogenation reaction. After the temperature of the high-pressure reactor stabilized, the hydrogenation reaction was maintained for 13 hours. Then, the hydrogen gas supply was stopped, and the high-pressure reactor was cooled and depressurized to room temperature and atmospheric pressure. The mixture was then filtered, and the filtrate was adjusted with glacial acetic acid. After adjusting the pH to 7, the mixture was transferred to a high-pressure reactor. The high-pressure reactor was then pressurized to -0.1 MPa and gradually heated to 70°C. Low-boiling-point substances were removed by vacuum distillation. 300 mL of toluene was added to the high-pressure reactor and stirred to dissolve the mixture. Then, 100 mL of deionized water was added and stirred for 20 min to disperse the mixture. The mixture was allowed to stand and separated. The organic phase was washed twice with deionized water and then transferred to another clean high-pressure reactor. The high-pressure reactor was then pressurized to -0.1 MPa and gradually heated to 130°C. Low-boiling-point substances were removed by vacuum distillation to obtain the hydrogenated aldehyde-ketone resin.

[0068] Example 5

[0069] This embodiment provides a method for preparing a hydrogenated aldehyde-ketone resin that does not contain free formaldehyde, including the following steps:

[0070] Step I: Preparation of aldehyde-ketone resin solution

[0071] Weigh out 60g of acetophenone, 10g of paraformaldehyde and 245mL of isopropanol and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the reaction flask to 68℃. Add 0.60g of sodium hydroxide to the reaction flask and keep the mixture at this temperature for 5 hours to obtain an aldehyde-ketone resin solution.

[0072] Step II: Preparation of hydrogenated aldehyde-ketone resin

[0073] The aldehyde-ketone resin solution prepared in step I was transferred to a high-pressure reactor and stirred. Then, 0.34 g of the nickel catalyst prepared in Example 2 was added to the high-pressure reactor. After the high-pressure reactor was sealed, the air in the reactor was first replaced with nitrogen three times, and then the nitrogen in the reactor was replaced with hydrogen six times. The heating temperature of the high-pressure reactor was set to 135°C, and hydrogen gas at a pressure of 4.5 MPa was continuously introduced for the hydrogenation reaction. After the temperature of the high-pressure reactor stabilized, the hydrogenation reaction was maintained for 14 hours. Then, the hydrogen gas supply was stopped, and the high-pressure reactor was cooled and depressurized to room temperature and atmospheric pressure. The mixture was then filtered, and the filtrate was adjusted with glacial acetic acid. After adjusting the pH to 7, the mixture was transferred to a high-pressure reactor. The high-pressure reactor was then pressurized to -0.1 MPa, and the temperature was gradually increased to 70-80°C. Low-boiling-point substances were removed by vacuum distillation. 300 mL of toluene was added to the high-pressure reactor, and after stirring to dissolve, 100 mL of deionized water was added. The mixture was stirred and dispersed for 25 min, allowed to stand, and separated. The organic phase was washed twice with deionized water and then transferred to another clean high-pressure reactor. The high-pressure reactor was then pressurized to -0.1 MPa, and the temperature was gradually increased to 140°C. Low-boiling-point substances were removed by vacuum distillation to obtain the hydrogenated aldehyde-ketone resin.

[0074] Example 6

[0075] This embodiment provides a method for preparing a hydrogenated aldehyde-ketone resin that does not contain free formaldehyde, including the following steps:

[0076] Step I: Preparation of aldehyde-ketone resin solution

[0077] Weigh out 70g of acetophenone, 10g of paraformaldehyde and 320mL of isobutanol and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the reaction flask to 75℃. Add 0.58g of potassium hydroxide to the reaction flask and keep the mixture at this temperature for 6 hours to obtain an aldehyde-ketone resin solution.

[0078] Step II: Preparation of hydrogenated aldehyde-ketone resin

[0079] The aldehyde-ketone resin solution prepared in step I was transferred to a high-pressure reactor and stirred. Then, 0.35 g of the nickel catalyst prepared in Example 3 was added to the high-pressure reactor. After the high-pressure reactor was sealed, the air in the reactor was first replaced with nitrogen three times, and then the nitrogen in the reactor was replaced with hydrogen six times. The heating temperature of the high-pressure reactor was set to 140°C, and hydrogen gas at a pressure of 5 MPa was continuously introduced to carry out the hydrogenation reaction. After the temperature of the high-pressure reactor stabilized, the hydrogenation reaction was maintained for 15 hours. Then, the hydrogen supply was stopped, and the high-pressure reactor was cooled and depressurized to room temperature and atmospheric pressure. The mixture was then filtered, and the filtrate was adjusted with glacial acetic acid. After pH=7, the solution was transferred to a high-pressure reactor. The high-pressure reactor was then evaporated to -0.1 MPa and gradually heated to 70-80°C. Low-boiling-point substances were removed by vacuum distillation. 300 mL of toluene was added to the high-pressure reactor and stirred to dissolve. 100 mL of deionized water was then added to the high-pressure reactor and stirred to disperse for 30 min. The mixture was allowed to stand and separated. The organic phase was washed twice with deionized water and then transferred to another clean high-pressure reactor. The high-pressure reactor was then evaporated to -0.1 MPa and gradually heated to 150°C. Low-boiling-point substances were removed by vacuum distillation to obtain the hydrogenated aldehyde-ketone resin.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 6 is that copper nitrate was not added in step 2 during the preparation of the nickel catalyst used.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Example 6 is that the nickel catalyst used is replaced with Raney nickel.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 6 is that acetic acid was added to the aldehyde-ketone resin solution prepared in step I after the reaction was completed to adjust the pH of the system to 7.

[0086] Comparative Example 4

[0087] The difference between this comparative example and Example 6 is that acetic acid was added to the aldehyde-ketone resin solution prepared in step I after the reaction was completed to adjust the pH of the system to 3.

[0088] Comparative Example 5

[0089] The difference between this comparative example and Example 6 is that the paraformaldehyde used in step I was replaced with 40 wt% formaldehyde.

[0090] Performance testing:

[0091] The hydroxyl values ​​of the hydrogenated aldehyde-ketone resins prepared in Examples 4-6 and Comparative Examples 1-4 were determined in accordance with the standard GB / T 12008.3-2009 "Plastics - Polyether Polyols - Part 3: Determination of Hydroxyl Value".

[0092] The free formaldehyde content in the hydrogenated aldehyde-ketone resins prepared in Examples 4-6 and Comparative Examples 1-4 was determined according to the standard GB / T 32684-2016 "Determination of Free Formaldehyde Content in Plastic Phenolic Resins".

[0093] The hydrogenated aldehyde-ketone resins prepared in Examples 4-6 and Comparative Examples 1-4 were mixed and dissolved with toluene to prepare a toluene test sample with a solid content of 50%. The Gardner color of the test sample was determined according to the standard GB / T 22295-2008 "Method for Determination of Color of Transparent Liquids (Gardner Colorimetric)". The specific test data are shown in Table 1 below.

[0094] Table 1 - Performance Test Data of Samples

[0095]

[0096] Data Analysis:

[0097] Comparative analysis of the data in Table 1 shows that the free formaldehyde content of the hydrogenated aldehyde-ketone resin prepared by this invention is reduced to 0.018-0.020 ppm, the hydroxyl value reaches 73-77 mgKOH / g, and the Gardner color is reduced to 0-1. All performance test data are superior to the comparative example. This indicates that the present invention, by preparing a nickel catalyst supported on a silicon-aluminum substrate using nickel and copper, and catalytically hydrogenating an alkaline aldehyde-ketone resin solution prepared by the condensation of paraformaldehyde and acetophenone in an anhydrous environment, not only effectively obtains hydrogenated aldehyde-ketone resin with stable hydroxyl value and extremely low color, but also effectively reduces the free formaldehyde content in the hydrogenated aldehyde-ketone resin, thus improving the wide applicability of the hydrogenated aldehyde-ketone resin in high-end coatings, adhesives, and electronic materials.

[0098] Figure 1 Based on the aldehyde-ketone resin solution prepared in Example 3, acetic acid was added to the aldehyde-ketone resin solution to adjust the pH of the reaction solution to neutral. The solvent was removed by vacuum distillation at 60°C and -0.1 MPa. 500 mL of toluene was added to the reaction system and heated to 80°C until the system dissolved. 100 mL of purified water was added to the reaction system, and the mixture was stirred for 20-30 min. After standing and separating the liquids, the organic phase was washed three times with purified water. The organic phase was then removed by vacuum distillation at 90°C and -0.1 MPa to obtain the infrared spectrum of the ketone-aldehyde resin product.

[0099] Figure 2 and Figure 3 In comparison, Figure 3 The aromatic characteristic absorption region (1500-1600 cm⁻¹) -1 700-900cm -1 The peak intensity decreased significantly, while the absorption region of saturated hydrocarbons (2850-2960 cm⁻¹) showed a more pronounced decrease. -11350-1450cm -1 The enhanced peak intensity fully demonstrates that the reduction of benzene rings was effectively reduced during the preparation of hydrogenated aldehyde-ketone resin in Example 6.

[0100] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde, characterized in that, Includes the following steps: S1. Under an inert gas atmosphere, acetophenone, paraformaldehyde and solvent are mixed and stirred. The reaction system is heated to 60-75℃. An inorganic base is added to the reaction system and the reaction is kept at the temperature for 4-6 hours to obtain an aldehyde-ketone resin solution. S2. The aldehyde-ketone resin solution and nickel catalyst are added to a high-pressure reactor for high-pressure hydrogenation to obtain hydrogenated aldehyde-ketone resin. The nickel catalyst comprises an active metal composed of a silicon-aluminum-based support and nickel and copper. The mass fraction of nickel is 55-60%, and the molar ratio of nickel to copper is 10-15:

1. The high-pressure hydrogenation operation includes: adding aldehyde-ketone resin solution and nickel catalyst into a high-pressure reactor and mixing and stirring; after sealing the high-pressure reactor, first replacing the air in the high-pressure reactor with inert gas 3 times, then replacing the inert gas in the high-pressure reactor with hydrogen 6 times; setting the heating temperature of the high-pressure reactor to 130-140℃; continuously introducing hydrogen gas at a pressure of 4-5MPa for hydrogenation reaction; after the temperature of the high-pressure reactor stabilizes, maintaining the hydrogenation reaction for 13-15 hours; and then post-processing to obtain hydrogenated aldehyde-ketone resin. The weight ratio of the nickel catalyst to the acetophenone used in step S1 is 1:150-200. The post-treatment includes: after the reaction is complete, stopping the hydrogen supply, cooling and depressurizing the high-pressure reactor to room temperature and atmospheric pressure, filtering, adjusting the pH of the filtrate to 7 with glacial acetic acid and transferring it to the high-pressure reactor, depressurizing the high-pressure reactor to -0.1 MPa, gradually heating the high-pressure reactor to 70-80°C, removing low-boiling substances under reduced pressure, adding toluene to the high-pressure reactor, stirring to dissolve, adding deionized water to the high-pressure reactor, stirring and dispersing for 20-30 minutes, allowing it to stand and separate, washing the organic phase twice with deionized water and transferring it to another clean high-pressure reactor, depressurizing the high-pressure reactor to -0.1 MPa, then gradually heating to 130-150°C, removing low-boiling substances under reduced pressure to obtain hydrogenated aldehyde-ketone resin.

2. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 1, characterized in that, In step S1, the weight ratio of acetophenone to paraformaldehyde is 5-7:1, the weight ratio of acetophenone to inorganic base is 80-120:1, the inorganic base is any one of potassium hydroxide, sodium hydroxide, and calcium hydroxide, the weight ratio of solvent to acetophenone is 1:3-4, and the solvent is any one of methanol, ethanol, isopropanol, and isobutanol.

3. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 1, characterized in that, The nickel catalyst is obtained by the following steps: A1. Add the active metal salt to deionized water and mix. Stir at room temperature until the system dissolves. Add the silica-alumina-based support to the reaction system. Add ammonia to the reaction system and adjust the pH of the system to 5-6. Impregnate for 30-50 min. Add ammonia to the reaction system and adjust the pH of the system to 9-10. Let it stand for aging for 8-10 h. After post-treatment, obtain the nickel catalyst precursor. A2. The nickel catalyst precursor is placed in a tube furnace for aerobic roasting, and then reduced roasting is carried out in a reducing gas atmosphere to obtain the nickel catalyst.

4. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 3, characterized in that, In step A1, the ratio of the active metal salt to deionized water is 1g:10mL, the active metal salt is composed of nickel nitrate and copper nitrate in a molar ratio of 10-15:1, the mass fraction of ammonia is 20%, and the post-treatment includes: after the reaction is complete, filtration is performed, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 90-100℃ and dried to constant weight to obtain a nickel catalyst precursor with a nickel content of 55-60%.

5. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 3, characterized in that, In step A2, the aerobic roasting temperature is 360-400℃, the roasting time is 3-4h, and the roasting atmosphere is air; the reduction roasting temperature is 380-420℃, the roasting time is 4-5h, and the roasting atmosphere is a mixture of hydrogen and nitrogen in a volume ratio of 1:

10.

6. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 5, characterized in that, The silicon-aluminum based carrier is obtained by the following steps: B1. Add sodium silicate and aluminum nitrate to deionized water and mix. Stir at room temperature until the system is dissolved. Add polyethylene glycol to the reaction system and stir to disperse for 20-30 minutes. Add alkaline solution to the reaction system to adjust the pH of the system to 8-9. Age at room temperature for 4-6 hours. After post-treatment, obtain the silica-alumina-based support precursor. B2. The silicon-aluminum based carrier precursor is placed in a muffle furnace for calcination and then pulverized and passed through an 80-mesh sieve to obtain the silicon-aluminum based carrier.

7. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 6, characterized in that, In step B1, the ratio of sodium silicate, aluminum nitrate, polyethylene glycol, and deionized water is 70-80g:30-35g:10g:800mL, the alkaline solution is 20wt% ammonia water, and the post-treatment includes: after the reaction is complete, filtration is performed, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 90-100℃ and dried to constant weight to obtain the silica-alumina-based support precursor.

8. The method for preparing a hydrogenated aldehyde-ketone resin free of free formaldehyde according to claim 6, characterized in that, In step B2, the aerobic roasting temperature of the muffle furnace is 560-620℃, the time is 4-5 hours, and the atmosphere is air.

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