Low-voc polyurethane foaming catalyst and preparation process thereof

Abstract

The invention relates to the technical field of polyurethane foaming, in particular to a low-voc polyurethane foaming catalyst and a preparation process thereof.The preparation process comprises the following steps that firstly, raw materials are screened and pretreated; step 2, construction and preparation of a reaction system; 3, reaction raw material addition and reaction initiation; 4, monitoring and controlling a reaction process; 5, reaction completion judgment and post-treatment preparation; according to the preparation method, a unique preparation process is adopted, triethylene diamine is modified through polyether polyol and a long-chain alkylation reaction, it is ensured that the catalyst keeps good catalytic activity while voc emission is reduced, the problems that a traditional catalyst is high in voc emission and the performance is difficult to consider at the same time are effectively solved, and the preparation method is suitable for industrial production. And the double requirements of the polyurethane foaming process in the aspects of environmental protection and performance are met.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane foaming, and in particular to a low-voc polyurethane foaming catalyst and a preparation process. Background Art

[0002] Polyurethane foam materials are widely used in many fields such as construction, automobiles, furniture, etc. because of their good thermal insulation, sound absorption and noise reduction and buffering properties. In the polyurethane foaming process, catalysts play a key role, which can accelerate the reaction between isocyanate and polyol and ensure the smooth foaming process. Traditional polyurethane foaming catalysts are mainly amine catalysts, such as triethylenediamine (TEDA), which has high catalytic activity and can effectively promote the foaming reaction. However, TEDA is highly volatile and will release a large amount of volatile organic compounds (VOC) during use, which is harmful to the environment and human health. With the increase of environmental awareness, reducing the VOC emissions of polyurethane foaming catalysts has become a research hotspot, and the development of low-VOC and high-efficiency polyurethane foaming catalysts is imminent.

[0003] In the prior art, although traditional polyurethane foaming catalysts can ensure the foaming effect, the VOC emission problem is serious. The research and development of new low-VOC catalysts faces challenges. It is necessary to reduce the VOC content while maintaining or even improving the catalytic activity to meet the dual requirements of polyurethane foam material performance and environmental protection in actual production. Therefore, an innovative method is needed to improve the catalyst so that its environmental performance is improved while not affecting its application effect in the polyurethane foaming process. To this end, we provide a low-VOC polyurethane foaming catalyst and a preparation process. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a low-voc polyurethane foaming catalyst and a preparation process, thereby solving the technical problems mentioned in the background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A low-voc polyurethane foaming catalyst, characterized in that the foaming catalyst comprises a polyether polyol-modified triethylenediamine catalyst and a long-chain alkylated modified triethylenediamine catalyst; The polyether polyol-modified triethylenediamine catalyst comprises the following raw materials in molar parts: 1 part of triethylenediamine, 10 parts of polyoxypropylene glycol; The polyoxypropylene glycol is a product with a molecular weight of 2000 produced by BASF, and its molecular structure is rich in hydroxyl groups. The amount of hydroxyl substances in 1 mol of the polyether polyol is 1 mol; The triethylenediamine is a product produced by Akzo Nobel with a purity of 99%; The long-chain alkylated modified triethylenediamine catalyst comprises the following raw materials in molar parts: 1 part of triethylenediamine, 1.2 parts of dodecane bromide, 1.308 parts of anhydrous potassium carbonate; The triethylenediamine is a product produced by Dow Chemical Company with a purity of 99.5%; The dodecane bromide is an analytically pure product produced by Tokyo Chemical Industry Co., Ltd.; The anhydrous potassium carbonate was purchased from Sigma-Aldrich Company and was calcined at 200° C. for 2 hours before use.

[0006] In a possible implementation, the organic solvent in the low-voc polyurethane foaming catalyst preparation reaction is toluene, and the amount of toluene added is based on the reaction container and the dissolution of the raw materials, specifically 500-1000 mL, and the toluene is purchased from Sinopharm Chemical Reagent Co., Ltd.

[0007] In a possible implementation, the preparation process includes the following steps: Step 1: Raw material screening and pretreatment. According to the target modification method, triethylenediamine is selected as the basic foaming catalyst; polyoxypropylene glycol and dodecane bromide are selected as modifiers for polyether polyol modification and long-chain alkylation modification, respectively; sodium hydroxide is selected as the catalyst for the polyether polyol modification reaction, and anhydrous potassium carbonate is selected as the acid binding agent for the long-chain alkylation modification reaction; toluene is selected as the reaction solvent; The basic foaming catalyst is dried, specifically, the basic foaming catalyst triethylenediamine is dried, when the water content of triethylenediamine is lower than 0.5% by mass, it is stored in a dryer; when the water content is higher than 0.5% by mass, it is heated and dried at 80-100° C. for 2-4 hours to ensure that it does not contain water to prevent moisture absorption from affecting the reaction; Step 2: Construction and preparation of the reaction system, adding the treated solvent into a reaction vessel equipped with a stirring device, a thermometer, a reflux condenser and a nitrogen inlet pipe device, the specific reaction vessel is a four-necked flask or a three-necked flask; Turn on the stirring device and set a suitable stirring speed, specifically 150-200r / min, so that the solvent forms a stable flow state in the container, preparing for the subsequent addition and mixing of raw materials; Step 3: Adding reaction raw materials and initiating the reaction. The raw materials are fed according to different raw materials. In the preparation of the polyether polyol modified triethylenediamine catalyst, the molar ratio of triethylenediamine to polyoxypropylene glycol is 1:10; in the preparation of the long-chain alkylation modified triethylenediamine catalyst, the molar ratio of triethylenediamine to dodecane bromide and anhydrous potassium carbonate is 1:1.2:1.308. The base catalyst is added to the reaction container, and the required reaction catalyst is added at the same time. Stirring is maintained stable during the addition process to uniformly disperse the base catalyst and the reaction catalyst in the solvent to form a uniform reaction system; According to the modification method requirements, nitrogen is introduced to replace the air in the reaction container to prevent the raw materials from being oxidized during the reaction. Then, when preparing the polyether polyol modified triethylene diamine catalyst, the temperature is raised to 120°C at a rate of 5°C / min; when preparing the long-chain alkylation modified triethylene diamine catalyst, the temperature is raised to 80°C at a rate of 3°C / min. Add the modifier to the reaction vessel, pay close attention to the temperature change of the reaction system during the addition process, maintain the reaction temperature at 120-140°C in the preparation of polyether polyol modified triethylenediamine catalyst through oil bath; maintain the reaction temperature at 80°C-85°C in the preparation of long-chain alkylation modified triethylenediamine catalyst to avoid excessive temperature fluctuations leading to side reactions; Step 4: Monitoring and controlling the reaction process. During the reaction, select appropriate monitoring methods according to the modification method, specifically amine value determination and thin layer chromatography (TLC) monitoring. Take a small amount of the reaction solution for analysis every 1-2 hours. Determine the reaction progress based on the monitoring results, and control the reaction rate by adjusting the reaction temperature, stirring speed or lowering the oil bath temperature to ensure a smooth reaction; Step 5: Determination of reaction completion and post-processing preparation. When the monitoring data indicates that the reaction has reached the predetermined completion standard, the reaction is stopped; The reaction system is cooled to room temperature at a cooling rate of 2-3°C / min to prepare for the post-processing step; Step 6: Post-treatment and product purification, the reaction solution is transferred to a separatory funnel, 500 ml of deionized water is added to the reaction solution for preparing the polyether polyol modified triethylenediamine catalyst, the reaction solution is washed three times, each time oscillation for 3 minutes, each time standing for 10 minutes after washing, the aqueous phase and the organic phase are fully separated, and the lower aqueous phase is discarded; in the reaction solution for preparing the long-chain alkylated modified triethylenediamine catalyst, the filter cake is washed three times with 100 mL of toluene, the washing liquid is combined with the filtrate after each washing, and washed three times with 10% dilute hydrochloric acid solution and deionized water in sequence, after each addition of the washing liquid, the separatory funnel is oscillated for 5 minutes, each time after washing, the aqueous phase and the organic phase are stood for 15 minutes, the lower aqueous phase is discarded; the washed organic phase is transferred to the distillation flask of the rotary evaporator, the rotary evaporation temperature is set to 60 ° C, the vacuum degree is set to -0.09 MPa, and the rotary evaporation operation is performed to remove the residual solvent, water and unreacted low-boiling substances to obtain a preliminarily purified modified catalyst product.

[0008] In a possible implementation, during the preparation of the polyether polyol-modified triethylenediamine catalyst, the reaction is determined to be complete when the amine value is measured to determine the extent of the reaction, and the specific amine value is reduced to 95% of the theoretical value.

[0009] In a possible implementation, in the preparation process of the long-chain alkylated modified triethylenediamine catalyst, the brominated dodecane used is purified by vacuum distillation before use.

[0010] In a possible implementation, during the preparation of the long-chain alkylated modified triethylenediamine catalyst, the reaction progress is monitored by thin layer chromatography, and the specific developing agent ratio is : = 5:1.

[0011] In a possible implementation, the low-voc polyurethane foaming catalyst is used in a polyurethane foaming reaction.

[0012] Beneficial effects compared with the prior art: 1. In this scheme, the polyether polyol modified triethylenediamine catalyst of the present invention is a combination of triethylenediamine and polyoxypropylene glycol (hydroxyl molar ratio 1:10) and a small amount of sodium hydroxide. The molecular structure characteristics of the polyether polyol are used to reduce the volatility of triethylenediamine while optimizing its catalytic performance; in the long-chain alkylation modified triethylenediamine catalyst, triethylenediamine is combined with dodecane bromide (molar ratio 1:1.2) and an appropriate amount of anhydrous potassium carbonate to effectively reduce VOC emissions and maintain good activity by means of long-chain alkylation reaction. The two formulas meet different production needs and strongly promote the green and sustainable development of the polyurethane industry; 2. In this scheme, the present invention adopts a unique preparation process, and modifies triethylenediamine through polyether polyol and long-chain alkylation reaction, which reduces VOC emissions while ensuring that the catalyst maintains good catalytic activity, effectively solving the problem of high VOC emissions and difficult performance of traditional catalysts, and meeting the dual requirements of polyurethane foaming process in terms of environmental protection and performance; BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0014] Figure 1 The present invention is a flow chart of the preparation process steps. DETAILED DESCRIPTION

[0015] The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be implemented in various forms, so the present invention is not limited to the embodiments described below. In addition, in order to more clearly describe the present invention, components that are not connected with the invention will be omitted from the drawings. The technical solution in the embodiment of the present application is to solve the problems of the above-mentioned background technology, and the overall idea is as follows: Embodiment 1:

[0016] This embodiment introduces a low-voc polyurethane foaming catalyst and preparation process. Triethylenediamine is modified by polyether polyol to reduce volatile organic compound (voc) emissions while maintaining good catalytic activity to meet the environmental protection and performance requirements of the polyurethane foaming process.

[0017] 1. Raw material preparation

[0018] Polyether polyol: Polyoxypropylene diol produced by BASF was selected, and its molecular weight was 2000. The molecular structure of the polyoxypropylene diol is rich in hydroxyl groups, which provides active sites for its reaction with triethylene diamine. In 1 mol of the polyoxypropylene diol, the amount of hydroxyl substances is 1 mol. Its regular molecular structure gives it good stability, which is conducive to maintaining a stable state in the reaction system. Before use, the polyoxypropylene diol is placed in a vacuum drying oven and vacuum dried at 80°C for 6 hours to completely remove the moisture therein. The presence of moisture will react with isocyanate by side reactions, which will not only consume the raw materials, but also seriously affect the performance of the final polyurethane product, so it is very important to ensure the dryness of the raw materials.

[0019] Triethylenediamine: Triethylenediamine (TEDA) with a purity of 99% produced by Akzo Nobel is used. It is an efficient polyurethane foaming catalyst with strong alkalinity, which can significantly accelerate the reaction between isocyanate and polyol. However, its own volatility is high, and more VOC will be released during use. Since triethylenediamine is highly hygroscopic, it must be strictly stored in a dry environment before use. Specifically, when the water content of triethylenediamine is less than 0.5% by mass, it is stored in a dryer; when the water content is higher than 0.5% by mass, it is heated and dried at 80-100 ° C for 2-4 hours to ensure that it does not contain water to prevent moisture absorption from affecting the reaction. In this embodiment, the molar ratio of triethylenediamine to hydroxyl groups in polyoxypropylene glycol is set to 1:10, which is determined according to the reaction design and the expected product structure. This ratio helps to introduce a suitable number of polyether segments into the triethylenediamine molecule to optimize its performance.

[0020] Catalyst: A small amount of sodium hydroxide (NaOH) is used as a reaction catalyst. Sodium hydroxide is purchased from Sinopharm Chemical Reagent Co., Ltd. and needs to be ground into powder to ensure uniform dispersion in the reaction system, thereby improving the catalytic efficiency.

[0021] 2. Chemical reaction formula

[0022] (in, The molar ratio of triethylene diamine to the hydroxyl group in polyoxypropylene glycol in this embodiment is set to 1:10 according to different actual conditions of different polyether polyols).

[0023] 3. Reaction process

[0024] Step 1: Add 1000g of dried polyoxypropylene glycol (about 0.5mol based on its molecular weight) to a 2000mL four-necked flask equipped with a stirring device, a thermometer and a nitrogen inlet tube. Place the four-necked flask in an oil bath, turn on the stirring device, and stir at a speed of 150r / min to ensure that the polyoxypropylene glycol is fully and evenly distributed in the system. This step is to ensure that other raw materials added later can fully contact with the polyoxypropylene glycol, create good mixing conditions for the reaction, and enable the reaction to proceed more evenly and efficiently.

[0025] Step 2: Introduce nitrogen to replace the air in the reaction system to prevent triethylenediamine from being oxidized at high temperatures. Continue to introduce nitrogen for 5 minutes to ensure that the oxygen in the system is completely discharged. Then, slowly increase the temperature to 120°C at a rate of 5°C / min. Slowly increasing the temperature can avoid rapid temperature changes that may cause side reactions or local overheating, thereby ensuring the stability and controllability of the reaction.

[0026] Step 3: When the system temperature reaches 120°C, add 5.6g of triethylenediamine (about 0.05mol, calculated based on the set molar ratio and the amount of polyoxypropylene glycol) weighed in advance into the four-necked flask, and add 5g of sodium hydroxide powder at the same time. During the addition process, keep the stirring speed stable at 150r / min to ensure that the materials are evenly mixed. This allows triethylenediamine to fully contact with polyoxypropylene glycol, and reacts rapidly under the catalytic action of sodium hydroxide, promoting the reaction to proceed fully in the expected direction.

[0027] Step 4: Continue to heat up to 140°C and react at this temperature for 6 hours. During the reaction, take a small amount of the reaction solution every hour to measure the amine value. The change in the amine value can intuitively reflect the degree of the reaction. As the reaction progresses, triethylenediamine continues to react with polyoxypropylene glycol, and the amine value will gradually decrease. When the amine value decreases to about 95% of the theoretical value, the reaction is considered to be basically completed. This judgment is based on the stoichiometric relationship of the reaction and empirical data, indicating that most of the reactants have been converted into the target product at this time.

[0028] 4. Post-processing

[0029] Step 1: After the reaction is completed, cool the reaction solution to 80°C, and control the cooling rate at 2-3°C / min. Slow cooling can effectively avoid unstable product performance due to sudden temperature changes, and prevent problems such as crystallization or changes in molecular structure. Then transfer the reaction solution to a 2000mL separatory funnel, add 500mL of deionized water, wash the reaction solution 3 times, and oscillate the separatory funnel for 3 minutes each time. This operation is intended to remove residual sodium hydroxide, because sodium hydroxide has no effect after the reaction is completed and may affect the performance of subsequent products. After each washing, let the layers stand for 10 minutes to fully separate the aqueous phase and the organic phase, and discard the lower aqueous phase.

[0030] Step 2: The washed organic phase is transferred to a 500 mL distillation flask of a rotary evaporator, and the residual water and unreacted low-boiling substances are removed by rotary evaporation at 60°C and a vacuum degree of -0.09 MPa. This operation can further purify the product to obtain a pure polyether polyol-modified triethylenediamine catalyst.

[0031] Embodiment 2: In this embodiment, triethylenediamine is modified by a long-chain alkylation reaction, aiming to prepare a catalyst that can effectively reduce VOC emissions during the polyurethane foaming process and has good catalytic performance.

[0032] 1. Raw material preparation Triethylenediamine: High-purity triethylenediamine produced by Dow Chemical Company is used, with a purity of 99.5%. The triethylenediamine has high reactivity, and the nitrogen atoms in the molecular structure are rich in lone pairs of electrons, which can undergo nucleophilic substitution reactions with halogenated hydrocarbons, laying the foundation for subsequent long-chain alkylation modification. Because it is easy to absorb moisture, it needs to be stored in a dryer before use to ensure its dry state. Specifically, when the water content of triethylenediamine is lower than 0.5% by mass, it is stored in a dryer; when the water content is higher than 0.5% by mass, it is heated and dried at 80-100°C for 2-4 hours to ensure that it does not contain moisture and prevent moisture absorption from affecting the reaction. In this embodiment, according to the reaction design, the molar ratio of triethylenediamine to dodecane bromide is set to 1:1.2 to ensure that triethylenediamine can fully undergo alkylation reaction.

[0033] Bromododecane: Analytical pure bromododecane produced by Tokyo Chemical Industry Co., Ltd. was selected. Its bromine atom is highly active and can undergo efficient substitution reaction with triethylenediamine under appropriate reaction conditions. Before use, it was purified by vacuum distillation, and the fraction of 165-170°C was collected under a pressure of 10 mmHg to remove possible impurities and ensure the purity and efficiency of the reaction.

[0034] Acid binding agent: Anhydrous potassium carbonate was purchased from Sigma-Aldrich Company as an acid binding agent. Before the reaction, the anhydrous potassium carbonate was placed in a muffle furnace and calcined at 200°C for 2 hours to completely remove the moisture and adsorbed carbon dioxide therein, to ensure that it can fully play its acid binding role in the reaction, timely neutralize the hydrogen bromide generated by the reaction, and promote the reaction to proceed in the positive direction.

[0035] Organic solvent: Toluene provided by Sinopharm Chemical Reagent Co., Ltd. was selected as the reaction solvent. Toluene has good solubility and can fully dissolve triethylenediamine and dodecane bromide and evenly disperse them in the reaction system. Before use, 1000 mL of toluene was mixed and stirred with 50 g of anhydrous calcium chloride for 2 hours, and the supernatant was taken to remove the water therein to ensure that the reaction was carried out in an anhydrous environment to avoid interference of water on the reaction.

[0036] 2. Chemical reaction formula

[0037] (The molar ratio of triethylenediamine to dodecane bromide is 1:1.2) 3. Reaction process Step 1: Add 112.17g triethylenediamine (calculated as 1 mol based on its molecular weight) and 500mL dried toluene to a 1000mL three-necked flask equipped with a stirrer, a reflux condenser and a thermometer. Turn on the stirring device and stir at a speed of 200r / min for 30 minutes to fully dissolve the triethylenediamine in toluene to form a uniform and stable reaction system. A uniform reaction system helps the subsequent raw materials to fully contact and react, thereby improving the uniformity and efficiency of the reaction.

[0038] Step 2: Add 180.78g of anhydrous potassium carbonate (calculated as 1.308mol based on its molecular weight and the amount of dodecane bromide) into the three-necked flask and continue stirring for 15 minutes to evenly disperse the potassium carbonate in the reaction system. This step ensures that potassium carbonate reacts quickly with the generated hydrogen bromide in the subsequent reaction, maintains the stability of the pH of the reaction system, and promotes the smooth progress of the reaction.

[0039] Step 3: Slowly drop 299.12g of dodecane bromide (calculated as 1.2 mol according to the set molar ratio and the amount of triethylenediamine) through a constant pressure dropping funnel. The dropping time is controlled at 1.5 hours, and the dropping speed is about 2-3 drops / second. During the dropping process, the reaction system is heated to 80°C at a heating rate of 3°C / min, and the oil bath temperature is controlled to keep the reaction system temperature at 80°C-85°C. Slowly dropping dodecane bromide can avoid excessive reaction and prevent local overheating, so that dodecane bromide undergoes decomposition or other substitution reactions.

[0040] Step 4: After the addition is complete, continue the reaction at 80°C for 8 hours. During the reaction, the system will produce a white precipitate (mainly potassium bromide generated by the reaction of potassium carbonate and hydrogen bromide generated by the reaction). Take a small amount of the reaction solution every 2 hours and monitor the progress of the reaction by thin layer chromatography (TLC). Use silica gel plate as the stationary phase and petroleum ether and ethyl acetate (v:v=5:1) as the developing solvent. When TLC shows that the raw material triethylenediamine has basically disappeared, the reaction is considered to be basically completed.

[0041] 4. Post-processing Step 1: After the reaction is completed, the reaction solution is cooled to room temperature, and the cooling rate is controlled at 2-3°C / min. Slow cooling can prevent the product from crystallizing or other physical changes due to temperature changes, ensuring the stability of the product. Then filter through a Buchner funnel and filter paper to remove the solid precipitate (potassium bromide and unreacted potassium carbonate) in the reaction system. Wash the filter cake with 100mL of toluene three times, and combine the washing liquid with the filtrate after each washing to ensure the maximum recovery rate of the product and reduce the residue of the product in the filter cake.

[0042] Step 2: Transfer the combined organic phase to a 1000 mL separatory funnel and wash it three times with 10% dilute hydrochloric acid solution and deionized water. After each addition of the washing solution, shake the separatory funnel for 5 minutes. The dilute hydrochloric acid solution is used to remove unreacted potassium carbonate and possible alkaline impurities, and the deionized water is used to remove residual hydrochloric acid and other water-soluble impurities. After each washing, let it stand for 15 minutes to allow the organic phase and the aqueous phase to be fully separated, and discard the lower aqueous phase.

[0043] Step 3: The washed organic phase was transferred to a 250 mL distillation flask of a rotary evaporator, and toluene was removed by rotary evaporation at 60° C. and a vacuum degree of −0.09 MPa to obtain a long-chain alkylated modified triethylenediamine catalyst.

[0044] Experimental example: This experimental example aims to compare the differences in catalytic activity, foam physical properties and VOC content between the polyether polyol modified triethylenediamine catalyst (Example 1) and the long-chain alkylated modified triethylenediamine catalyst (Example 2) in the polyurethane foaming reaction, so as to evaluate the influence of each modification method on the performance of the triethylenediamine catalyst and provide a basis for selecting a better polyurethane foaming catalyst. For this purpose, three experimental groups are set up, namely Example 1, Example 2 and the control group.

[0045] 1. Catalytic activity test 1.1 Accurately weigh 10 g of polyether polyol, 15 g of isocyanate and 0.5 g of the modified triethylenediamine catalyst prepared in each example, place them in a reaction container at 30°C, and stir them evenly at a speed of 200 r / min to form Example Group 1 and Example Group 2. In addition, an equal amount of unmodified catalyst is added to the control group.

[0046] 1.2 Record the time when each catalyst starts the foaming reaction (foaming start time), accurate to seconds.

[0047] 1.3 Observe the changes in system temperature and the rate of bubble generation during the reaction, record the system temperature every 30 seconds, and evaluate the reaction rate.

[0048] Table 1: Foaming start time of different groups of catalysts

[0049] From the above data, although the unmodified catalyst has a fast initialization speed, the reaction rate is difficult to control, which can easily lead to an overly violent reaction and difficulty in obtaining an ideal foam structure. Although the modified catalyst has a longer initialization time, the reaction process is easier to control.

[0050] In addition, the modified catalyst of Example 1 has a moderate reaction rate and the system temperature rises steadily. During the reaction, the system temperature rises from 30°C to 40°C in the first 5 minutes, reaches 48°C in 10 minutes, and reaches 52°C in 15 minutes, and the bubble generation rate is relatively uniform.

[0051] The modified catalyst of Example 2 had a stable reaction process and the system temperature rose slowly. Within 5 minutes after the start of the reaction, the system temperature rose from 30°C to 35°C, reached 42°C in 10 minutes, and reached 50°C in 15 minutes, and bubbles were generated steadily.

[0052] The reaction rate of the unmodified catalyst in the control group was too fast, and the system temperature rose sharply in a short time. Within 3 minutes after the reaction started, the system temperature rose rapidly to 74°C, and bubbles were generated quickly and unevenly.

[0053] From the above data, the modified catalyst of Example 2 has a milder effect than that of Example 1, and its reaction rate is slower and more stable, while the unmodified catalyst of the control group has a too fast reaction rate and the temperature rises too quickly.

[0054] 2. Foam physical properties test 2.1 Use the modified catalyst in each example to prepare a polyurethane foam sample according to the above foaming reaction conditions, quickly pour the reaction mixture into a pre-prepared mold, and let it stand at room temperature for foaming molding.

[0055] 2.2 Use density testing equipment to measure the density of the foam sample and calculate the density deviation. The specific method is: randomly select 9 test points on the foam sample, measure the density of each point, and then calculate the average value of these density values and standard deviation , the density deviation is expressed as .

[0056] 2.3 Observe the cell structure of the foam by scanning electron microscopy (SEM), measure the cell size and analyze its distribution. Randomly select 50 cells from the SEM image and measure their diameters. ( ), count the number of cells in different diameter ranges, and calculate the average value of the cell diameter and distribution range.

[0057] Table 2: Average sample density, standard deviation, and average cell diameter of different groups of catalyst foaming

[0058] The foam test point density values ​​of the embodiment group are 0.42, 0.45, 0.48, 0.43, 0.46, 0.44, 0.47, 0.41, 0.43 respectively. , the density deviation is 0.440 0.025 The generated foam is uniform and delicate, and the pore size distribution is relatively narrow. Among the 50 pore measurement values, there are 22 pores with a pore diameter of 0.4-0.5mm and 28 pores with a pore diameter of 0.5-0.6mm. The pores are regular polygons and have good interconnectivity.

[0059] The foam test point density values ​​of the second embodiment group are 0.38, 0.39, 0.40, 0.41, 0.40, 0.39, 0.40, 0.41, 0.38 respectively. , the density deviation is 0.395 0.012 The generated foam structure is uniform. Among the 50 pore measurement values, there are 8 pores with a pore diameter of 0.3-0.4mm, 25 pores with a pore diameter of 0.4-0.5mm, 12 pores with a pore diameter of 0.5-0.6mm, and 5 pores with a pore diameter of 0.6-0.7mm. The pore shape is relatively regular and the connectivity is good.

[0060] The foam density deviation of the control group was 0.50 0.1 , and the generated foam has many large cells. Among the 50 measured cells, there are 18 cells of 0.8-1.0mm, 22 cells of 1.0-1.2mm, 8 cells of 1.2-1.5mm, and 2 cells of 1.5-2.0mm. The cell shapes are irregular and the sizes vary greatly.

[0061] The above data show that the catalyst modified by long-chain alkylation can make the foam more uniform and regular in shape during foaming, but the catalyst modified by polyether polyol can make the foam pore diameter more concentrated and the stability better during foaming.

[0062] 3. VOC content test 3.1 Catalyst VOC content detection: 1 g of the catalyst sample prepared in each example was accurately weighed and placed in a 20 mL headspace bottle and equilibrated at 80° C. for 30 minutes.

[0063] The headspace gas was extracted and analyzed using a headspace gas chromatography-mass spectrometer (HS-GC-MS) to determine the VOC content of the catalyst with an accuracy of 1 mg / kg.

[0064] 3.2 Testing of VOC release of foam products. Take the polyurethane foam products prepared in each example after the catalyst reaction and cut them into 10 cm 10cm The 5 cm small pieces were placed in a standard test environment (temperature 23°C, relative humidity 50%) for 24 hours.

[0065] Use gas chromatograph to detect the VOC release of foam products. Place the foam sample in a sealed sampling bag and extract the gas in the bag for analysis with an accuracy of 0.1 mg / m³.

[0066] Table 3: VOC content in different groups of catalysts and VOC release of foam products

[0067] The above data show that the modification of the catalyst effectively reduces the VOC content of the catalyst and the VOC emission of the foam product. Among them, the polyether polyol modification is the most effective in reducing the VOC content of the catalyst, and the long-chain alkylation modification is relatively good in reducing the VOC emission of the foam product, which meets the environmental protection requirements.

[0068] Embodiment three: This example further explores the effects of different formulation ratios of polyether polyol-modified triethylenediamine catalyst and long-chain alkylated modified triethylenediamine catalyst on their performance in polyurethane foaming reaction, aiming to determine the optimal formulation combination.

[0069] 1. Adjustment of the ratio of the polyoxypropylene glycol modified triethylenediamine catalyst formula The amount of triethylenediamine was kept constant at 1 part, and the molar amount of hydroxyl groups of polyoxypropylene glycol was adjusted to 8 parts and 12 parts respectively.

[0070] Table 4: Foaming start time, catalyst VOC content and product VOC release of foaming catalyst at different proportions of polyoxypropylene glycol

[0071] The above data show that when the molar amount of polyoxypropylene glycol hydroxyl group is 8 parts, it is found in the polyurethane foaming reaction test that the activity of the catalyst is reduced, the foaming start time is extended to 350 seconds, and the system temperature in the first 5 minutes during the reaction only rises from 30°C to 38°C, reaches 45°C at 10 minutes, and reaches 50°C at 15 minutes. The average density of the generated foam is 0.460g / cm³, the standard deviation of density is 0.030g / cm³, there are 18 pores with a diameter of 0.4-0.5mm, 25 pores with a diameter of 0.5-0.6mm, and 7 pores with a diameter of 0.6-0.7mm. The uniformity and connectivity of the pores are relatively poor. The catalyst VOC content test result is 60mg / kg, and the VOC release of the foam product is 1.0mg / m³. When the molar amount of polyoxypropylene glycol hydroxyl group is 12 parts, the catalyst activity is enhanced, but the foaming reaction rate is too fast, resulting in unstable foam structure. The foaming start time is shortened to 300 seconds. During the reaction, the system temperature rises rapidly from 30°C to 42°C in the first 5 minutes, reaches 50°C in 10 minutes, and reaches 55°C in 15 minutes. The average density of the generated foam is 0.420g / cm³, the standard deviation of the density is 0.028g / cm³, there are 20 pores with a pore diameter of 0.4-0.5mm, 22 pores with a pore diameter of 0.5-0.6mm, and 8 pores with a pore diameter of 0.6-0.7mm. Some large pores appear, and the pore shape is irregular. The catalyst VOC content test result is 45mg / kg, and the VOC release of the foam product is 0.9mg / m³.

[0072] 2. Adjustment of the formula ratio of long-chain alkylation modified triethylenediamine catalyst The amount of triethylenediamine was kept at 1 part, and the molar amount of dodecane bromide was adjusted to 1.0 part and 1.5 parts respectively, and the amount of anhydrous potassium carbonate was adjusted to 1.2 times the amount of dodecane bromide.

[0073] Table 5: Foaming start time, catalyst VOC content and product VOC release of foaming catalyst with different amounts of dodecane bromide

[0074] The above data shows that when the molar amount of dodecane bromide is 1.0 part, in the polyurethane foaming reaction, the foaming start time is extended to 420 seconds, the reaction process is relatively slow, the system temperature rises from 30°C to 33°C in the first 5 minutes, reaches 38°C in 10 minutes, and reaches 43°C in 15 minutes. The average density of the generated foam is 0.410g / cm³, the standard deviation of density is 0.015g / cm³, there are 12 pores with a diameter of 0.3-0.4mm, 28 pores with a diameter of 0.4-0.5mm, and 10 pores with a diameter of 0.5-0.6mm. The pore shape is regular but the overall foaming effect is not ideal. The catalyst VOC content test result is 70mg / kg, and the VOC release of the foam product is 1.2mg / m³. When the molar amount of dodecane bromide is 1.5 parts, although the reaction rate is improved, more side reactions occur. The generated foam has an odor and is yellow in color. The starting time of foaming is 360 seconds. During the reaction, the system temperature rises from 30°C to 37°C in the first 5 minutes, reaches 45°C in 10 minutes, and reaches 52°C in 15 minutes. The average density of the generated foam is 0.380g / cm³, the standard deviation of the density is 0.018g / cm³, there are 10 pores with a pore diameter of 0.3-0.4mm, 26 pores with a pore diameter of 0.4-0.5mm, and 14 pores with a pore diameter of 0.5-0.6mm. The catalyst VOC content test result is 55mg / kg, and the VOC release of the foam product is 1.1mg / m³.

[0075] Based on the catalytic data of the above catalysts with different formulations, the polyether polyol modified triethylenediamine catalyst formulation of 1 part triethylenediamine and 10 parts polyoxypropylene glycol ensures moderate catalytic activity while the distribution of foam cell size generated by foaming is relatively reasonable and has good stability; the long-chain alkylated modified triethylenediamine catalyst formulation of 1 part triethylenediamine, 1.2 parts dodecane bromide and 1.308 parts anhydrous potassium carbonate has outstanding performance in reducing the VOC release of foam products, which is only 1.0 mg / m³, and the foaming process is stable and the generated foam structure is uniform. These two formulations can achieve a better balance between environmental protection and performance requirements of polyurethane foaming process.

[0076] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A low-voc polyurethane foaming catalyst, characterized in that: The foaming catalyst includes a polyether polyol modified triethylene diamine catalyst and a long-chain alkylated modified triethylene diamine catalyst; The polyether polyol-modified triethylenediamine catalyst comprises the following raw materials in molar parts: 1 part of triethylenediamine, 10 parts of polyoxypropylene glycol; The polyoxypropylene glycol is a product with a molecular weight of 2000 produced by BASF, and its molecular structure is rich in hydroxyl groups. The amount of hydroxyl substances in 1 mol of the polyether polyol is 1 mol; The triethylenediamine is a product produced by Akzo Nobel with a purity of 99%; The long-chain alkylated modified triethylenediamine catalyst comprises the following raw materials in molar parts: 1 part of triethylenediamine, 1.2 parts of dodecane bromide, 1.308 parts of anhydrous potassium carbonate; The triethylenediamine is a product produced by Dow Chemical Company with a purity of 99.5%; The dodecane bromide is an analytically pure product produced by Tokyo Chemical Industry Co., Ltd.; The anhydrous potassium carbonate was purchased from Sigma-Aldrich Company and was calcined at 200° C. for 2 hours before use.

2. The low-voc polyurethane foaming catalyst according to claim 1, characterized in that The organic solvent in the preparation reaction of the low-voc polyurethane foaming catalyst is toluene. The amount of toluene is added according to the reaction container and the dissolution of the raw materials, specifically 500-1000 mL. The toluene is purchased from Sinopharm Chemical Reagent Co., Ltd.

3. A preparation process of a low-voc polyurethane foaming catalyst, characterized in that: The preparation process comprises the following steps: Step 1: Raw material screening and pretreatment. According to the target modification method, triethylenediamine is selected as the basic foaming catalyst; polyoxypropylene glycol and dodecane bromide are selected as modifiers for polyether polyol modification and long-chain alkylation modification, respectively; sodium hydroxide is selected as the catalyst for the polyether polyol modification reaction, and anhydrous potassium carbonate is selected as the acid binding agent for the long-chain alkylation modification reaction; toluene is selected as the reaction solvent; The basic foaming catalyst is dried, specifically, the basic foaming catalyst triethylenediamine is dried, when the water content of triethylenediamine is lower than 0.5% by mass, it is stored in a dryer; when the water content is higher than 0.5% by mass, it is heated and dried at 80-100° C. for 2-4 hours to ensure that it does not contain water to prevent moisture absorption from affecting the reaction; Step 2: Construction and preparation of the reaction system, adding the treated solvent into a reaction vessel equipped with a stirring device, a thermometer, a reflux condenser and a nitrogen inlet pipe device, the specific reaction vessel is a four-necked flask or a three-necked flask; Turn on the stirring device and set a suitable stirring speed, specifically 150-200r / min, so that the solvent forms a stable flow state in the container, preparing for the subsequent addition and mixing of raw materials; Step 3: Adding reaction raw materials and initiating the reaction. The raw materials are fed according to different raw materials. In the preparation of the polyether polyol modified triethylenediamine catalyst, the molar ratio of triethylenediamine to polyoxypropylene glycol is 1:10; in the preparation of the long-chain alkylation modified triethylenediamine catalyst, the molar ratio of triethylenediamine to dodecane bromide and anhydrous potassium carbonate is 1:1.2:1.

308. The base catalyst is added to the reaction container, and the required reaction catalyst is added at the same time. Stirring is maintained stable during the addition process to uniformly disperse the base catalyst and the reaction catalyst in the solvent to form a uniform reaction system; According to the modification method requirements, nitrogen is introduced to replace the air in the reaction container to prevent the raw materials from being oxidized during the reaction. Then, when preparing the polyether polyol modified triethylene diamine catalyst, the temperature is raised to 120°C at a rate of 5°C / min; when preparing the long-chain alkylation modified triethylene diamine catalyst, the temperature is raised to 80°C at a rate of 3°C / min. Add the modifier to the reaction vessel, pay close attention to the temperature change of the reaction system during the addition process, maintain the reaction temperature at 120-140°C in the preparation of polyether polyol modified triethylenediamine catalyst through oil bath; maintain the reaction temperature at 80°C-85°C in the preparation of long-chain alkylation modified triethylenediamine catalyst to avoid excessive temperature fluctuations leading to side reactions; Step 4: Monitoring and controlling the reaction process. During the reaction, select appropriate monitoring methods according to the modification method, specifically amine value determination and thin layer chromatography (TLC) monitoring. Take a small amount of the reaction solution for analysis every 1-2 hours. Determine the reaction progress based on the monitoring results, and control the reaction rate by adjusting the reaction temperature, stirring speed or lowering the oil bath temperature to ensure a smooth reaction; Step 5: Determination of reaction completion and post-processing preparation. When the monitoring data indicates that the reaction has reached the predetermined completion standard, the reaction is stopped; The reaction system is cooled to room temperature at a cooling rate of 2-3°C / min to prepare for the post-processing step; Step 6: Post-treatment and product purification, the reaction solution is transferred to a separatory funnel, 500 ml of deionized water is added to the reaction solution for preparing the polyether polyol modified triethylenediamine catalyst, the reaction solution is washed three times, each time oscillation for 3 minutes, and each washing is allowed to stand for 10 minutes to separate the aqueous phase and the organic phase, and the lower aqueous phase is discarded; in the reaction solution for preparing the long-chain alkylated modified triethylenediamine catalyst, the filter cake is washed three times with 100 mL of toluene, and the washing liquid and the filtrate are combined after each washing, and washed three times with 10% dilute hydrochloric acid solution and deionized water in sequence, and after each addition of the washing liquid, the separatory funnel is oscillated for 5 minutes, and each washing is allowed to stand for 15 minutes to separate the aqueous phase and the organic phase, and the lower aqueous phase is discarded; The washed organic phase was transferred to the distillation flask of a rotary evaporator, the rotary evaporation temperature was set to 60°C, the vacuum degree was set to -0.09 MPa, and a rotary evaporation operation was performed to remove residual solvent, moisture and unreacted low-boiling substances to obtain a preliminarily purified modified catalyst product.

4. A process for preparing a low-voc polyurethane foaming catalyst as claimed in claim 3, characterized in that: During the preparation of the polyether polyol-modified triethylenediamine catalyst, the reaction is judged to be complete when the amine value is measured to judge the degree of reaction, and the specific amine value is reduced to 95% of the theoretical value.

5. A process for preparing a low-voc polyurethane foaming catalyst as claimed in claim 3, characterized in that: In the preparation process of the long-chain alkylated modified triethylenediamine catalyst, the brominated dodecane used is purified by vacuum distillation before use.

6. A process for preparing a low-voc polyurethane foaming catalyst as claimed in claim 3, characterized in that: During the preparation of the long-chain alkylated modified triethylenediamine catalyst, the reaction progress was monitored by thin layer chromatography. The specific developing agent ratio was: : = 5:

1.

7. A process for preparing a low-voc polyurethane foaming catalyst as claimed in claim 3, characterized in that: The low-voc polyurethane foaming catalyst is used in polyurethane foaming reaction.

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