A catalyst for polyurethane foaming and a method for preparing the same

Abstract

The present application relates to polyurethane material preparation technical field, especially in kind of catalyst for polyurethane foaming and preparation method thereof, including the following mass ratio of component composition: main catalyst N, N-dioctylcyclohexylamine 55%, synergistic catalyst bismuth stearate 35%, auxiliary functional agent 3-aminopropyl triethoxysilane 10%; The main catalyst is hydrophobic tertiary amine, which is used for controlling the foaming reaction rate and providing long-chain hydrophobic groups;The synergistic catalyst is an organometallic compound, which is used to accelerate the gel reaction and enhance the hydrophobic and adhesive properties;The auxiliary functional agent is a silane compound, which is used to improve the interfacial adhesion;In the present application, by scientifically proportioning the main catalyst, the synergistic catalyst and the auxiliary functional agent, and combining with strict preparation process control, the comprehensive performance of polyurethane foaming catalyst is balanced and optimized, and the controllability of the reaction, the stability of the foam structure, the mechanical properties and the storage stability are considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane material preparation, in particular to a catalyst for polyurethane foaming and a preparation method thereof. BACKGROUND

[0002] The polyurethane foaming agent is a substance that can initiate chemical reaction to produce gas in the process of polyurethane material preparation, so as to form a porous structure of the material. It gives polyurethane excellent properties such as light weight, heat insulation, shock absorption, and is widely used in thermal insulation building materials, packaging materials, automotive interiors and other fields. The catalyst used is a key substance for controlling the progress of the polyurethane foaming reaction, which can accelerate the polymerization reaction between isocyanate and polyol, determine the creaming time and gel time of foaming, and directly affect the structure and performance of the foam.

[0003] The traditional catalyst has many defects: some catalysts lack long-chain hydrophobic groups in the main catalyst, resulting in low foam closed cell rate and poor water resistance. For example, the use of short-chain tertiary amine catalysts has a high 24h water absorption rate of the foam, which is difficult to meet the use requirements in a humid environment; some catalysts lack effective synergistic catalysts, which makes the gel reaction insufficient, the mechanical properties of the foam such as tensile strength are weak, and the foaming rate is too slow, affecting the production efficiency; some catalysts have improper selection of auxiliary functional agents, poor adhesion to the base material, and poor stability during storage; in addition, the traditional preparation process has poor control of the water content of raw materials and does not use inert environment protection, which can cause rapid decline in catalyst activity, abnormal foaming reaction, and uneven foam structure.

[0004] Therefore, the present application provides a catalyst for polyurethane foaming and a preparation method thereof, which comprehensively improves the performance of the catalyst by selecting N,N-dioctylcyclohexylamine as the main catalyst, bismuth stearate as the synergistic catalyst, and 3-aminopropyltriethoxysilane as the auxiliary functional agent, and using strict raw material dehydration treatment, nitrogen protection inert environment, and precise mixing and filtration purification process. The catalyst can balance the foaming reaction rate, increase the foam closed cell rate to 92±1%, reduce the 24h water absorption rate to 2.1±0.2%, increase the tensile strength to 1.8±0.1MPa, increase the adhesion to the base material to 8.5±0.3N / cm, and still retain 95±1% of the activity after 6 months of storage, effectively solving the defects of the traditional catalyst. SUMMARY

[0005] The technical problems solved by the present application are the difficult control of the reaction of the traditional catalyst, poor foam performance, unstable storage, and process defects.

[0006] In view of the deficiencies of the prior art, the present application provides a catalyst for polyurethane foaming and a preparation method thereof, thereby solving the technical problems mentioned in the background art.

[0007] To achieve the above object, the present application is implemented by the following technical solutions:

[0008] A catalyst for polyurethane foaming, comprising the following components in mass percentage: main catalyst N,N-dioctylcyclohexylamine 55%, synergistic catalyst bismuth stearate 35%, auxiliary functional agent 3-aminopropyltriethoxysilane 10%; the main catalyst is a hydrophobic tertiary amine, used for regulating the foaming reaction rate and providing long-chain hydrophobic groups; the synergistic catalyst is an organic metal compound, used for accelerating the gel reaction and enhancing the hydrophobic and adhesive properties; the auxiliary functional agent is a silane compound, used for improving the interfacial adhesion.

[0009] In a possible implementation manner, the preparation raw materials of the main catalyst N,N-dioctylcyclohexylamine are cyclohexylamine: 1-bromooctane: sodium hydroxide = 1:2.2:2.5 in molar ratio; the preparation includes the following steps: dissolving cyclohexylamine and 1-bromooctane in anhydrous ethanol, adding sodium hydroxide solid, refluxing at 78℃ for 8h until the residual 1-bromooctane is <0.5%; after cooling and filtering, collecting the 180-190℃ fraction by vacuum distillation to obtain a product with a purity ≥98%.

[0010] In a possible implementation manner, the preparation raw materials of the synergistic catalyst bismuth stearate are stearic acid: bismuth nitrate = 3:1 in molar ratio; the preparation includes the following steps: dissolving stearic acid in toluene and heating to 60℃, dropping bismuth nitrate aqueous solution into the stearic acid toluene solution at a rate of 2mL / min, stirring at 60℃ for 2h; after standing and separating, washing the organic phase to neutral, removing the solvent and vacuum drying at 60℃ for 12h, crushing to 100 mesh to obtain a product with a purity ≥99%.

[0011] In a possible implementation manner, a catalyst preparation method for polyurethane foaming is provided for preparing the above catalyst, and the method includes a raw material pretreatment step: the main catalyst N,N-dioctylcyclohexylamine is dehydrated in a vacuum drying box at 80℃ and 0.09MPa for 4h to make the moisture content ≤0.05%; the bismuth stearate is sieved through a 100 mesh screen to ensure no caking; and the 3-aminopropyltriethoxysilane is sealed to avoid hydrolysis.

[0012] In a possible implementation manner, the method further includes an inert environment preparation step: nitrogen is introduced into the reaction container at a flow rate of 50L / h for 30min to make the oxygen content in the container ≤0.1%; and the reaction container is a 100L four-necked reaction flask made of 316L stainless steel.

[0013] In a possible implementation manner, the method includes the following mixing steps:

[0014] (1) Main catalyst dissolving: N,N-dioctylcyclohexylamine was added into the reaction container, and stirred at 300 rpm and 40±1℃ for 10 min until completely melted;

[0015] (2) Synergistic catalyst dispersion: Bismuth stearate powder was added in 5 times with 10 min interval, and stirred at 40℃ and 300 rpm for 2 h until the solution was uniform light yellow;

[0016] (3) Auxiliary functional agent mixing: The temperature was reduced to below 30℃, and 3-aminopropyl triethoxysilane was added, and stirred at 200 rpm for 30 min until the solution was transparent.

[0017] In one possible implementation, the method further comprises a purification filtering and storage step: the mixed solution is filtered through a precision filter with a pore size of 0.22 μm, the operating pressure is 0.2 MPa, and the transmittance of the filtrate is ≥95%; the finished product is stored in a 50 L brown glass sealed tank, the storage conditions are humidity ≤30%, temperature 20-25℃, shelf life 6 months, and sampling detection is performed every month during the period.

[0018] Compared with the prior art, the beneficial effects are:

[0019] In the scheme, by scientifically proportioning the main catalyst, synergistic catalyst and auxiliary functional agent, and combining with strict preparation process control, the comprehensive performance of the polyurethane foaming catalyst is balanced and optimized, taking into account the controllability of the reaction, the stability of the foam structure, the mechanical properties and the storage stability.

[0020] Specifically, the catalyst uses 55% N,N-dioctylcyclohexylamine as the main catalyst, which can effectively regulate the foaming reaction rate (cream time 45±2s), avoiding the problems of too fast reaction (30±2s) and uneven foam structure of Comparative Example 1 due to the lack of long chain structure in the main catalyst; 35% bismuth stearate as a synergistic catalyst can accelerate the gelation reaction, cooperate with the main catalyst to form a reasonable reaction rhythm, solve the defects of Comparative Example 2 due to the lack of this component, such as slow reaction (80±5s), low closed cell rate (65±4%) and insufficient mechanical properties (tensile strength 0.9±0.1 MPa), and increase the closed cell rate of the foam to 92±1% and the tensile strength to 1.8±0.1 MPa; 10% 3-aminopropyl triethoxysilane enhances the interfacial bonding with the substrate through silicon-oxygen bonds, and the adhesion is 8.5±0.3 N / cm, which is better than the effect of Comparative Example 3 using fatty amine (5.5±0.2 N / cm).

[0021] Meanwhile, the process is strictly implemented in the preparation process, such as raw material dehydration (moisture of main catalyst ≤0.05%), nitrogen protection (oxygen content ≤0.1%), precise mixing (stage control of temperature, speed and time), and purification and filtration (transmittance ≥95%) to avoid the problems of emulsion, performance drop (closed cell rate 50±5%) caused by moisture in Comparative Example 4 (without dehydration) and low activity retention rate (45±4%) caused by oxidation in Comparative Example 5 (without inert protection), so that the activity retention rate of the catalyst is still 95±1% after 6 months of storage. The synergy of component design and process control enables the catalyst to not only stabilize and control the reaction process during polyurethane foaming, but also significantly improve the structural integrity, mechanical strength, water resistance and interfacial bonding force of the foam, while ensuring long-term storage stability, meeting the stringent requirements of industrial production on the comprehensive performance of the catalyst. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present application will be described in detail, but the present application can be implemented in various different forms, and therefore the present application is not limited to the embodiments described below;

[0023] The technical solutions in the embodiments of the present application solve the problems in the background art, and the general idea is as follows:

[0024] Embodiment 1

[0025] This embodiment introduces a catalyst preparation method for polyurethane foaming, which is as follows:

[0026] I. Selection and preparation of core raw materials

[0027] (1) Main catalyst: N, N-dioctylcyclohexylamine (self-made, key hydrophobic tertiary amine)

[0028] The raw material is mainly used to control the foaming reaction rate and provide long-chain hydrophobic groups; the raw material composition is cyclohexylamine: 1-bromooctane: sodium hydroxide = 1:2.2:2.5 by mole ratio;

[0029] When synthesized in the laboratory, 0.1 mol of cyclohexylamine, 0.22 mol of 1-bromooctane and 100 mL of anhydrous ethanol were first added to a 500 mL three-necked flask and stirred to dissolve; then 0.25 mol of sodium hydroxide solid was slowly added, and the addition was divided into 5 times to avoid violent boiling, and then the temperature was raised to 78°C and refluxed for 8h, during which a GC-2014 gas chromatograph (Shimadzu, capillary column DB-5, FID detector) was used for monitoring, and when the residual 1-bromooctane was <0.5%, the reaction was completed;

[0030] After cooling, the sodium chloride was removed by filtration, and then the product was collected by RE-52AA vacuum rotary evaporator (rotation speed: 0-150 rpm, temperature range: 20-100℃, vacuum degree: 0.095 MPa) under reduced pressure (vacuum degree: 0.095 MPa, 180-190℃) distillation to obtain a colorless transparent liquid with purity ≥98%;

[0031] For industrial production, a 5000L continuous reactor made of 316L stainless steel was used, with ethanol as the solvent, reaction temperature controlled at 80℃, pressure at 0.3MPa, and residence time at 10h. Finally, the product was purified by a rectification tower with 20 theoretical plates.

[0032] (2) Synergistic catalyst: bismuth stearate (self-made, to improve gelation and adhesion)

[0033] It can accelerate the gelation reaction, and the stearic acid chain can enhance the hydrophobic and adhesive properties. The raw material composition is stearic acid: bismuth nitrate = 3:1 (molar ratio).

[0034] During preparation, 0.3mol of stearic acid was dissolved in 200mL of toluene and heated to 60℃ to form a transparent solution. Then, 0.1mol of bismuth nitrate was dissolved in 50mL of deionized water and slowly added to the stearic acid toluene solution at a rate of 2mL / min. The mixture was stirred at 60℃ for 2h, during which a white precipitate was formed.

[0035] After standing and layering, the water phase was discarded, and the organic phase was washed with deionized water until it was neutral (pH=7). Then, the toluene was removed by RE-52AA vacuum rotary evaporator (parameters as above) at 80℃ and 0.09MPa.

[0036] Finally, the product was dried in a DZF-6050 vacuum drying oven (temperature control range: 50-200℃, vacuum degree: ≤10Pa, volume: 50L) at 60℃ for 12h, and then crushed to 100 mesh using a WFJ-15 crusher (crushing particle size: 50-200 mesh adjustable, output: 10kg / h) to obtain a product with purity ≥99%.

[0037] (3) Auxiliary functional agent: 3-aminopropyltriethoxysilane (commercially available, CAS: 919-30-2)

[0038] For industrial production, a 5000L continuous reactor made of 316L stainless steel was used, with ethanol as the solvent, reaction temperature controlled at 80℃, pressure at 0.3MPa, and residence time at 10h. Finally, the product was purified by a rectification tower with 20 theoretical plates.

[0039] II. Complete preparation process (50L batch, full nitrogen protection)

[0040] (1) Raw material pretreatment (key: strictly control moisture)

[0041] N,N-dioctylcyclohexylamine is dehydrated by a DZF-6050 type vacuum drying oven (parameters are the same as above) (80°C, 0.09 MPa, 4 h), and the moisture content is detected by a Karl Fischer moisture meter, which should be ≤0.05%;

[0042] The bismuth stearate is sieved through a 100-mesh screen to ensure that there are no lumps;

[0043] 3-aminopropyltriethoxysilane is checked for sealing before opening to confirm that there is no delamination or turbidity, and if there is hydrolysis, it needs to be discarded;

[0044] (II) Inert environment preparation

[0045] A 100L, 316L stainless steel four-necked reaction flask (containing a thermometer interface, a nitrogen inlet, a stirring port, and a charging port, with a pressure resistance of 0.1 MPa) is connected to a GN-300 type nitrogen generator (gas purity 99.999%, flow rate 0-300 L / h adjustable) to generate nitrogen gas (flow rate 50 L / h) for 30 min, and an oxygen content detector is used to confirm that the oxygen content in the flask is ≤0.1% to avoid oxidation of the raw materials;

[0046] (III) Main catalyst dissolution (step 1)

[0047] 27.5 kg of N,N-dioctylcyclohexylamine (accounting for 55%) is added, a JJB-50 type stirrer (paddle stirring blade, speed 0-500 rpm adjustable, power 1.5 kW) is turned on, the speed is adjusted to 300 rpm, a HH-S10 type constant temperature water bath (temperature control range room temperature-100°C, accuracy ±0.5°C, volume 100L) is started, and the temperature is raised to 40°C (±1°C), and the stirring is maintained for 10 min until the raw materials are completely melted (viscous liquid at room temperature, easy to flow at 40°C);

[0048] (IV) Dispersion of organometallic catalyst (step 2)

[0049] The 17.5 kg of bismuth stearate powder is added in 5 times (3.5 kg each time, interval 10 min) to avoid powder agglomeration; maintain 40°C, JJB-50 type stirrer speed 300 rpm stirring for 2 h, until the solution is uniform light yellow (no white particles, the dispersion effect can be confirmed by sampling observation);

[0050] (V) Mixing of auxiliary functional agents (step 3)

[0051] The HH-S10 type constant temperature water bath is turned off, and the temperature is naturally lowered to below 30°C (monitored in real time by a thermometer), and 5 kg of 3-aminopropyltriethoxysilane (accounting for 10%) is added; the speed of the JJB-50 type stirrer is reduced to 200 rpm, and the stirring is continued for 30 min to ensure that the silane is completely dissolved (the solution is transparent, without delamination);

[0052] (6) Purification and filtration

[0053] The mixed solution was passed through a GMP-0.22 precision filter (organic filter membrane, pore size 0.22 μm, stainless steel shell, operating pressure 0.3 MPa) at an operating pressure of 0.2 MPa to collect the filtrate (to remove trace amounts of undispersed bismuth stearate particles); the solution was tested for clarity after filtration (transmittance ≥ 95%, determined by ultraviolet spectrophotometry at a wavelength of 550 nm);

[0054] (7) Storage of finished product

[0055] The filtrate was filled into a 50 L brown glass sealed storage tank (with a polytetrafluoroethylene sealing ring, pressure resistance 0.05 MPa), and after sealing, the batch number and preparation date were marked; the storage conditions were a dry and ventilated warehouse (humidity ≤ 30%), temperature 20-25 °C, and shelf life 6 months (monthly sampling was required for detection, and if stratification occurred, the solution was re-stirred and used evenly);

[0056] III. Quality control indicators (to ensure that the performance meets the standards)

[0057] The appearance requirement was a light yellow transparent liquid, which was detected by visual observation (no precipitation, stratification); the moisture content should be ≤ 0.1%, which was detected by Karl Fischer titration; the viscosity at 25 °C should be between 80-100 mPa·s, which was determined using an NDJ-5S type rotary viscometer; the effective ingredient content should be ≥ 99%, which was detected by a GC-2014 type gas chromatograph (internal standard method, using n-dodecane as the internal standard); the storage stability requirement was that there should be no stratification within 6 months, which was confirmed by static observation (once a month);

[0058] IV. Matters needing attention in equipment operation

[0059] When the JJB-50 type stirrer was used, the distance between the paddle and the bottom of the flask should be ≥ 5 cm before starting to avoid wear; the rotation speed should be strictly controlled, as a rotation speed exceeding 400 rpm could cause the solution to splash;

[0060] When the GN-300 type nitrogen generator was providing nitrogen, the nitrogen micro-positive pressure (pressure in the flask 0.01-0.02 MPa) should be maintained throughout the process to prevent external water vapor from entering (which could be monitored by a pressure gauge);

[0061] The filter membrane of the GMP-0.22 type precision filter should be replaced after filtering each batch to avoid clogging and affecting the filtration efficiency of the next batch.

[0062] Example 2:

[0063] I. Selection and preparation of core raw materials

[0064] (1) Main catalyst: N,N-dioctylcyclohexylamine (self-made, key hydrophobic tertiary amine)

[0065] The raw material composition is cyclohexylamine: 1-bromooctane: sodium hydroxide = 1: 2.0: 2.2 (1-bromooctane and sodium hydroxide ratio is reduced compared to Example 1);

[0066] In the laboratory synthesis, 0.1 mol of cyclohexylamine, 0.20 mol of 1-bromooctane, and 90 mL of anhydrous ethanol were added to a 500 mL three-necked flask and stirred to dissolve; 0.22 mol of sodium hydroxide solid was slowly added (in 5 portions), and the temperature was raised to 75°C and refluxed for 6h (shortened compared to Example 1), and GC monitoring was terminated when the residual 1-bromooctane was <0.5%;

[0067] After cooling and filtering, the vacuum rotary evaporator (parameters same as Example 1) was used for reduced pressure distillation (170-180°C) to collect the fraction, with a purity of ≥97%;

[0068] In industrial production, a 5000L continuous reactor was used, the reaction temperature was 75°C, the pressure was 0.28MPa, the residence time was 8h (shortened compared to Example 1), the theoretical plate number of the rectifying column was 18, and the purity after purification was ≥97%;

[0069] (II) Synergistic catalyst: bismuth stearate (self-made)

[0070] The raw material composition is stearic acid: bismuth nitrate = 2.8: 1 (stearic acid ratio is reduced);

[0071] During preparation, 0.28 mol of stearic acid was dissolved in 180 mL of toluene (solvent reduced), and stirred at 60°C; 0.1 mol of bismuth nitrate was dissolved in 40 mL of deionized water, the drop rate was 1.5 mL / min (slowed down), and stirred at 60°C for 1.5h (shortened);

[0072] After standing and layering, washing to neutral, rotary evaporator 80°C to remove toluene, vacuum drying box 55°C drying 10h (shortened), pulverizer to 80 mesh (particle size relaxed), purity ≥96%;

[0073] (III) Auxiliary functional agent: 3-aminopropyl triethoxysilane (purchased, same as Example 1)

[0074] II. Complete preparation process (50L batch, full nitrogen protection)

[0075] (I) Raw material pretreatment

[0076] N,N-dioctylcyclohexylamine was dehydrated by vacuum drying box (65°C, 0.09MPa, 2.5h) (lower temperature and time compared to Example 1), and the moisture content was ≤0.06% (standard relaxed) by Karl Fischer detection;

[0077] Bismuth stearate was sieved through an 80 mesh screen (lower mesh number compared to Example 1);

[0078] (II) Inert environment preparation

[0079] 100L four-port reaction flask was purged with nitrogen (flow rate 40 L / h, duration 25 min (shortened), oxygen content detector confirmed oxygen content ≤0.15% (standard relaxed);

[0080] (III) Main catalyst dissolution (step 1)

[0081] Add 25 kg of N,N-dioctylcyclohexylamine (50% by weight, reduced compared to Example 1), JJB-50 type stirrer speed 280 rpm (reduced), constant temperature water bath heater temperature raised to 38°C (reduced), stirring 8 min (shortened) to melt;

[0082] (IV) Organic metal catalyst dispersion (step 2)

[0083] Add 15 kg of bismuth stearate powder in 5 portions (3 kg each, 30% by weight, reduced compared to Example 1), interval 8 min (shortened); maintain 38°C, 280 rpm stirring for 1.5 h (shortened), solution is light yellow (allowing a small amount of fine particles);

[0084] (V) Auxiliary functional agent mixing (step 3)

[0085] Cool to below 30°C, add 10 kg of 3-aminopropyltriethoxysilane (20% by weight, increased compared to Example 1); stirrer speed 180 rpm (reduced), stirring 25 min (shortened), solution is slightly turbid and transparent (standard relaxed);

[0086] (VI) Purification and filtration

[0087] Collect the filtrate through a GMP-0.45 type precision filter (pore size relaxed), operating pressure 0.18 MPa (reduced); transmittance ≥90% (standard relaxed);

[0088] (VII) Finished product storage

[0089] Pack into a 50L brown glass jar, storage conditions are humidity ≤40% (standard relaxed), temperature 18-25°C, shelf life 5 months (shortened), sample monthly for testing;

[0090] III. Quality control indicators

[0091] Appearance: light yellow turbid liquid (allowing slight turbidity); moisture content ≤0.15% (standard relaxed); 25°C viscosity 60-80 mPa·s (reduced range); active ingredient content ≥96% (standard reduced); storage stability no delamination within 5 months (shortened);

[0092] IV. Equipment operation notes

[0093] Stirrer blade to flask bottom distance ≥ 6 cm (relaxed); nitrogen generator to maintain the pressure in the flask 0.005-0.015 MPa (reduce positive pressure); filter to replace filter membrane every 2 batches (extend replacement period).

[0094] Example 3:

[0095] I. Selection and preparation of core raw materials

[0096] (I) Main catalyst: N, N-dioctylcyclohexylamine (self-made)

[0097] The raw material composition is cyclohexylamine: 1-bromooctane: sodium hydroxide = 1:2.4:2.8 (increase the proportion of 1-bromooctane and sodium hydroxide) by mole ratio;

[0098] When synthesized in the laboratory, 0.1 mol of cyclohexylamine, 0.24 mol of 1-bromooctane, and 110 mL of anhydrous ethanol (increase the solvent) were added to a 500 mL three-necked flask and stirred to dissolve; 0.28 mol of sodium hydroxide was added (in 5 portions), and the temperature was increased to 80°C and refluxed for 10 hours (extend the time), and GC was used to monitor the termination;

[0099] After cooling and filtering, vacuum distillation (190-200°C) was used to collect the fraction, and the purity was ≥99%;

[0100] The reaction temperature for industrial production was 85°C, the pressure was 0.32 MPa, the residence time was 12 hours (extended), the number of theoretical plates of the rectifying column was 22, and the purity was ≥99%;

[0101] (II) Synergistic catalyst: bismuth stearate (self-made)

[0102] The raw material composition is stearic acid: bismuth nitrate = 3.2:1 (increase the proportion of stearic acid) by mole ratio;

[0103] 0.32 mol of stearic acid was dissolved in 220 mL of toluene (increase the solvent) and stirred at 65°C; 0.1 mol of bismuth nitrate was dissolved in 60 mL of deionized water, the drop rate was 2.5 mL / min (speed up), and stirring was carried out at 65°C for 2.5 hours (extend);

[0104] After washing, vacuum drying at 65°C for 14 hours (extend), and crushing to 120 mesh (refine), the purity was ≥99.5%;

[0105] (III) Auxiliary functional agent: 3-aminopropyltriethoxysilane (purchased, same as Example 1)

[0106] II. Complete preparation process (50L batch, full nitrogen protection)

[0107] (I) Raw material pretreatment

[0108] N,N-dioctylcyclohexylamine was dehydrated in a vacuum drying oven at 90°C, 0.098 MPa for 5 hours (extended), with water content ≤0.04% (strict); bismuth stearate was sieved through a 120-mesh screen (refined);

[0109] (II) Inert environment preparation

[0110] Nitrogen was introduced for 40 minutes (extended), with oxygen content ≤0.08% (strict);

[0111] (IV) Main catalyst dissolution (step 1)

[0112] 30 kg of N,N-dioctylcyclohexylamine was added (60% share, increased), the stirrer speed was 320 rpm (increased), the constant-temperature water bath was heated to 42°C (increased), and stirring was continued for 12 minutes (extended) until melting;

[0113] (IV) Dispersion of organometallic catalyst (step 2)

[0114] 20 kg of bismuth stearate powder was added in 5 portions (4 kg each, 40% share, increased), with 12 minutes (extended) between each addition; stirring was maintained at 42°C and 320 rpm for 2.5 hours (extended), and the solution was uniformly bright yellow (without particles);

[0115] (V) Mixing of auxiliary functional agents (step 3)

[0116] The temperature was reduced to below 28°C (strict), and 5 kg of 3-aminopropyl triethoxysilane was added (10% share, same as in Example 1); the stirrer speed was 220 rpm (increased), and stirring was continued for 35 minutes (extended), with the solution being completely transparent;

[0117] (VI) Purification and filtration

[0118] The solution was filtered through a GMP-0.1 μm precision filter (strict pore size), with an operating pressure of 0.22 MPa (increased) and a transmittance ≥97% (strict);

[0119] (VII) Storage of finished product

[0120] The storage humidity was ≤25% (strict), the temperature was 20-22°C (narrowed), the shelf life was 7 months (extended), and samples were taken every 2 weeks for testing;

[0121] III. Quality control indicators

[0122] Appearance: bright yellow transparent liquid; water content ≤0.08%; 25°C viscosity 90-110 mPa·s (increased range); effective ingredient content ≥99.5% (strict); storage stability without separation for 7 months (extended);

[0123] IV. Notes on equipment operation

[0124] Stirrer blade to flask bottom distance ≥ 5.5 cm (strict); nitrogen pressure 0.015-0.025 MPa (increase positive pressure); filter membrane replaced for each batch (strict).

[0125] Comparative Example 1:

[0126] I. Selection and preparation of core raw materials

[0127] (I) Main catalyst: N, N-dimethylcyclohexylamine (short-chain tertiary amine, no hydrophobic group)

[0128] The molar ratio of raw material composition is cyclohexylamine: bromomethane: sodium hydroxide = 1:2.2:2.5 (replace 1-bromooctane with bromomethane);

[0129] When synthesized in the laboratory, 0.1 mol of cyclohexylamine, 0.22 mol of bromomethane (gas, passed through a conduit), and 100 mL of anhydrous ethanol were added to a 500 mL three-necked flask and stirred to dissolve; 0.25 mol of sodium hydroxide was added, and the temperature was raised to 60°C and refluxed for 4 h (due to the high activity of bromomethane, the time was shortened);

[0130] After cooling and filtering, the fraction was collected by distillation under reduced pressure (80-90°C), with a purity of ≥98%;

[0131] (II) Synergistic catalyst: bismuth stearate (same as Example 1)

[0132] (III) Auxiliary functional agent: 3-aminopropyltriethoxysilane (same as Example 1)

[0133] II. Complete preparation process (50L batch)

[0134] Identical to Example 1 (raw material usage: main catalyst 27.5 kg, bismuth stearate 17.5 kg, silane 5 kg);

[0135] III. Quality control indicators

[0136] Appearance: colorless transparent liquid; moisture content ≤0.1%; 25°C viscosity 40-60 mPa·s (reduced due to short-chain structure); active ingredient content ≥99%; storage stability 5 months (stability decreased due to lack of long-chain hydrophobic groups);

[0137] IV. Equipment operation notes

[0138] Same as Example 1, but bromomethane is a toxic gas, so a gas leak detector (additional equipment) needs to be added.

[0139] Comparative Example 2:

[0140] I. Selection and preparation of core raw materials

[0141] Only main catalyst (N,N-dioctylcyclohexylamine, same as Example 1) and auxiliary functional agent (3-aminopropyltriethoxysilane, same as Example 1) are reserved, without bismuth stearate;

[0142] II. Complete preparation process (50L batch)

[0143] (I) Raw material pretreatment: Only the main catalyst and silane are pretreated (same as Example 1);

[0144] (II) Inert environment preparation: same as Example 1;

[0145] (III) Main catalyst dissolution: add 32.5kg N,N-dioctylcyclohexylamine (65% by weight, to make up for the absence of bismuth stearate), same as Example 1 step;

[0146] (IV) Skip the "organic metal catalyst dispersion" step;

[0147] (V) Auxiliary functional agent mixing: add 7.5kg silane (15% by weight), same as Example 1 stirring parameters;

[0148] (VI) Purification and filtration: same as Example 1;

[0149] (VII) Finished product storage: same as Example 1;

[0150] III. Quality control indicators

[0151] Appearance: colorless transparent liquid (light yellow without bismuth stearate); moisture content ≤0.1%; 25℃ viscosity 70-80mPa·s; active ingredient content ≥99%; storage stability 6 months (without metal ion influence, stability slightly increased).

[0152] Comparative Example 3:

[0153] I. Selection and preparation of core raw materials

[0154] (I) Main catalyst and synergistic catalyst: same as Example 1;

[0155] (II) Auxiliary functional agent: n-dodecylamine (fatty amine, no siloxane bond), commercially available purity ≥98%;

[0156] II. Complete preparation process (50L batch)

[0157] Completely consistent with Example 1 (silane replaced by n-dodecylamine, amount 5kg);

[0158] III. Quality control indicators

[0159] Appearance: light yellow turbid liquid (due to poor compatibility of fatty amine with main catalyst); moisture content ≤0.12%; viscosity at 25℃ 110-130 mPa·s (increased due to poor compatibility); active ingredient content ≥97%; storage stability 3 months (easily stratified).

[0160] Comparative Example 4:

[0161] I. Selection and preparation of core raw materials

[0162] The main catalyst, synergistic catalyst and auxiliary functional agent were prepared as in Example 1, but none of them were subjected to dehydration treatment:

[0163] Moisture content of main catalyst ≥0.5% (≤0.05% in Example 1);

[0164] Bismuth stearate retains crystal water (moisture content ≥1.0%);

[0165] Silane is not sealed and absorbs water vapor (hydrolysis rate ≥5%);

[0166] II. Complete preparation process (50L batch)

[0167] The dehydration step in the "raw material pretreatment" is omitted, and the rest is the same as in Example 1;

[0168] III. Quality control indicators

[0169] Appearance: light yellow turbid liquid (due to phase separation caused by moisture); moisture content ≥0.8%; viscosity at 25℃ 150-180 mPa·s (increased due to the influence of hydrolysis products); active ingredient content ≥95%; storage stability 1 month (moisture accelerates degradation).

[0170] Comparative Example 5:

[0171] I. Selection and preparation of core raw materials

[0172] The same as in Example 1;

[0173] II. Complete preparation process (50L batch)

[0174] The "inert environment preparation" step is omitted (the reaction system is exposed to air, oxygen content ≥21%), and the rest is the same as in Example 1;

[0175] III. Quality control indicators

[0176] Appearance: brownish yellow liquid (due to oxidation of tertiary amine); moisture content ≤0.1%; viscosity at 25℃ 120-140 mPa·s (increased due to oxidation products); active ingredient content ≥90% (oxidative degradation); storage stability 2 months (oxidation products accelerate stratification).

[0177] Experimental Example:

[0178]

[0179] Experimental illustration

[0180] Comparative Example 1: Without long-chain hydrophobic groups in the main catalyst, the closed cell rate and water resistance decreased significantly, and the foaming rate was too fast, resulting in uneven foam structure;

[0181] Comparative Example 2: After the absence of bismuth stearate, the gel reaction was insufficient, the closed cell rate and mechanical properties were greatly reduced, and the foaming rate was too slow;

[0182] Comparative Example 3: After replacing the silane with a fatty amine, the interfacial adhesion decreased, and the poor compatibility led to reduced storage stability;

[0183] Comparative Example 4: Uncontrolled moisture in raw materials caused abnormal foaming (too fast) and foam defects (extremely low closed cell rate), and rapid degradation during storage;

[0184] Comparative Example 5: Without nitrogen protection, the catalyst was oxidized, the activity retention rate was low, and the mechanical properties decreased.

[0185] Examples 1-3: All maintain good performance, Example 3 has the best performance due to optimized raw material ratios and strict process; Example 2, although with relaxed parameters, still meets the basic requirements, demonstrating the formulation's fault tolerance.

[0186] Example 1 exhibits significant advantages in overall performance, with the following specific advantages:

[0187] Reaction rate is balanced and controllable: milk-white time is 45±2s, and gel time is moderate, avoiding the foaming too fast (30±2s) caused by the improper type of main catalyst in Comparative Example 1, and overcoming the slow reaction (80±5s) caused by the absence of synergistic catalyst in Comparative Example 2, which can stabilize and control the foaming process and ensure uniform foam structure;

[0188] Excellent foam structure and performance: closed cell rate reaches 92±1%, much higher than Comparative Examples 1 (75±3%), 2 (65±4%), and 4 (50±5%), effectively improving the foam's basic insulation and waterproof performance; 24h water absorption rate is only 2.1±0.2%, significantly lower than Comparative Examples 1 (10.5±0.5%) and 4 (15.3±0.8%), demonstrating good hydrophobic performance; tensile strength is 1.8±0.1MPa, better than most comparative examples, with strong mechanical stability;

[0189] Interface bonding and storage stability are prominent: the adhesion to the substrate is 8.5±0.3 N / cm, higher than that of Comparative Example 3 (5.5±0.2 N / cm), Comparative Example 4 (4.0±0.2 N / cm), etc., ensuring that the foam is firmly bonded to the substrate; the activity retention rate after 6 months of storage is 95±1%, much higher than that of Comparative Example 3 (60±5%) and Comparative Example 5 (45±4%), indicating that the formulation compatibility and anti-degradation ability are excellent, and the foam can be stored for a long time;

[0190] The formulation and process compatibility are good: the long-chain hydrophobic design of the main catalyst, the gel promotion effect of the synergistic catalyst, and the interface enhancement effect of the auxiliary functional agent form a synergy, and the process control of raw material dehydration and inert environment is reasonable, avoiding the defects of Comparative Example 4 (not dehydrated) and Comparative Example 5 (without inert protection), and performing best in performance balance and process reliability.

[0191] Finally, it should be noted that: obviously, the above examples are only examples for clearly illustrating the present application, and are not limitations on the embodiments. Based on the above description, those skilled in the art can also make other different forms of changes or variations. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A catalyst for polyurethane foaming, characterized in that, The product comprises the following components in the indicated mass percentages: 55% N,N-dioctylcyclohexylamine as the main catalyst, 35% bismuth stearate as the co-catalyst, and 10% 3-aminopropyltriethoxysilane as the auxiliary functional agent. The main catalyst is a hydrophobic tertiary amine used to regulate the foaming reaction rate and provide long-chain hydrophobic groups. The co-catalyst is an organometallic compound used to accelerate the gelation reaction and enhance hydrophobic and adhesive properties. The auxiliary functional agent is a silane compound used to improve interfacial adhesion.

2. The catalyst for polyurethane foaming as described in claim 1, characterized in that, The main catalyst, N,N-dioctylcyclohexylamine, is prepared from raw materials in a molar ratio of cyclohexylamine:1-bromooctane:sodium hydroxide = 1:2.2:2.

5. The preparation includes the following steps: cyclohexylamine and 1-bromooctane are dissolved in anhydrous ethanol, and solid sodium hydroxide is added. The mixture is refluxed at 78°C for 8 hours until the 1-bromooctane residue is <0.5%. After cooling and filtration, the fraction distilled at 180-190°C under reduced pressure is collected to obtain a product with a purity ≥98%.

3. The catalyst for polyurethane foaming as described in claim 1, characterized in that, The synergistic catalyst bismuth stearate is prepared from raw materials with a molar ratio of stearic acid: bismuth nitrate = 3:

1. The preparation includes the following steps: dissolving stearic acid in toluene and heating to 60°C; adding bismuth nitrate aqueous solution dropwise to the stearic acid-toluene solution at a rate of 2 mL / min; stirring at 60°C for 2 h; allowing the mixture to stand and separate into layers, washing the organic phase until neutral, removing the solvent, and then vacuum drying at 60°C for 12 h; pulverizing to 100 mesh to obtain a product with a purity ≥ 99%.

4. A method for preparing a catalyst for polyurethane foaming according to any one of claims 1-3, characterized in that, The method includes a raw material pretreatment step: the main catalyst N,N-dioctylcyclohexylamine is dehydrated in a vacuum drying oven at 80°C and 0.09 MPa for 4 hours to make the moisture content ≤0.05%; bismuth stearate is sieved through a 100-mesh sieve to ensure no lumps; 3-aminopropyltriethoxysilane is sealed and stored to avoid hydrolysis.

5. The method for preparing a catalyst for polyurethane foaming as described in claim 4, characterized in that, The method also includes an inert environment preparation step: nitrogen gas is introduced into the reaction vessel at a flow rate of 50 L / h for 30 min, so that the oxygen content in the vessel is ≤0.1%; the reaction vessel is a 100L, 316L stainless steel four-necked reaction flask.

6. The method for preparing a catalyst for polyurethane foaming as described in claim 4, characterized in that, The method includes the following mixing steps: (1) Dissolution of the main catalyst: N,N-dioctylcyclohexylamine was added to the reaction vessel and stirred at 300 rpm and 40±1℃ for 10 min until completely melted; (2) Co-catalyst dispersion: Bismuth stearate powder was added in 5 portions, with an interval of 10 min between each addition. The mixture was stirred at 40℃ and 300 rpm for 2 h until the solution was uniformly pale yellow. (3) Mixing of auxiliary functional agents: Cool down to below 30°C, add 3-aminopropyltriethoxysilane, stir at 200 rpm for 30 min until the solution is transparent.

7. The method for preparing a catalyst for polyurethane foaming as described in claim 4, characterized in that, The method further includes purification, filtration, and storage steps: the mixture is filtered through a precision filter with a pore size of 0.22 μm, the operating pressure is 0.2 MPa, and the transmittance of the filtrate is ≥95%; The finished product is stored in a 50L brown glass sealed container under the following conditions: humidity ≤30% and temperature 20-25℃. The shelf life is 6 months, and monthly sampling tests are conducted during this period.

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