PEG400 composite system and method for softening, removing and curing phenolic resin

Abstract

The invention provides a PEG400 composite system and a method for softening, removing and curing phenolic resin, and the PEG400 composite system comprises the following components by mass: 65-75% of PEG400, 8-12% of polyoxyethylene lauryl ether, 5-8% of hydroxyapatite nanorods, 2-3% of a pH buffer system and 5-12% of a phase change temperature control agent. According to the invention, the PEG400 composite system comprising the components is adopted to remove the cured phenolic resin of the pressing plate of the hot press, so that the three-in-one technical effect of rapid softening, lossless removal and surface protection is realized.

Description

Technical Field

[0001] This invention belongs to the field of phenolic resin removal technology, and particularly relates to a PEG400 composite system and a method for softening and removing cured phenolic resin. Background Technology

[0002] In the production of phenolic resin products, the hot press platen (such as one made of 45# steel) often develops a stubborn residue layer due to resin dripping and curing, leading to pits on the surface of subsequent products. Traditional mechanical scraping easily causes scratches on the platen surface, increasing the roughness Ra value from 1.6μm to over 3.2μm, resulting in pits on the surface of subsequent products. Patent CN109439301A uses pure PEG400 or its aqueous solution for cleaning, but the cured resin layer on the hot press platen is typically 0.5–2mm thick. Due to its high crosslinking density, the swelling time at room temperature requires several hours, and continuous heating to 50-80℃ is necessary, resulting in high energy consumption. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a polyethylene glycol 400 composite system and a method for softening and removing cured phenolic resin. The method uses a PEG400 composite system to achieve the three-in-one technical effect of rapidly softening cured phenolic resin, non-destructive removal and surface protection.

[0004] This invention provides a PEG400 composite system, comprising the following components by mass fraction:

[0005] 65-75% PEG400, 8-12% lauryl alcohol polyoxyethylene ether, 5-8% hydroxyapatite nanorods (HA), 2-3% pH buffer system and 5-12% phase change temperature control agent.

[0006] Preferably, the hydroxyapatite nanorods have a diameter of 50–80 nm and a length of 100–200 nm.

[0007] Preferably, the pH buffer system is citrate-triethanolamine.

[0008] Preferably, the pH value of the pH buffer system is 6.5 to 7.0.

[0009] Preferably, the phase change temperature control agent is selected from disodium hydrogen phosphate dodecahydrate.

[0010] This invention provides a method for softening and removing cured phenolic resin, comprising the following steps:

[0011] The residual cured phenolic resin on the surface of the pressure plate is blasted with dry ice to obtain pretreated cured phenolic resin.

[0012] The PEG400 composite system described in the above technical solution is electromagnetically atomized on the surface of the pretreated and cured phenolic resin, followed by pulsed ultrasonic-infrared radiation synergistic treatment, and then ultra-high pressure water jet supplemented with soft ceramic abrasive to peel off the softened phenolic resin.

[0013] Preferably, the pulse interval of the pulsed ultrasound is 100-200ms, the heating-pause time ratio of infrared radiation is 3:0.9-1.1, and the surface temperature of the pressure plate is controlled to be ≤60℃.

[0014] Preferably, the frequency of the pulsed ultrasound is 24–26 kHz, and the power density is 0.55–0.65 W / cm². 2 ;

[0015] The infrared radiation used has a wavelength of 2–3 μm and a power density of 480–510 W / cm². 2 .

[0016] Preferably, the co-processing time is 8 to 10 minutes.

[0017] Preferably, the pressure of the ultra-high pressure water jet is 80-100 MPa, the spray angle is 25-30°, and the temperature is 35-40°.

[0018] The particle size of soft ceramic abrasive is 50–100 μm.

[0019] This invention provides a PEG400 composite system, comprising the following components by mass fraction: 65-75% PEG400, 8-12% lauryl alcohol polyoxyethylene ether, 5-8% hydroxyapatite nanorods, 2-3% pH buffer system, and 5-12% phase change temperature control agent. This invention achieves a three-in-one technical effect of rapid softening, non-destructive removal, and surface protection by using the PEG400 composite system comprising the above components to remove cured phenolic resin from hot press plates. Detailed Implementation

[0020] This invention provides a PEG400 composite system, comprising the following components by mass fraction:

[0021] 65-75% PEG400, 8-12% lauryl alcohol polyoxyethylene ether, 5-8% hydroxyapatite nanorods, 2-3% pH buffer system and 5-12% phase change temperature control agent.

[0022] The PEG400 composite system provided by this invention comprises 65-75% PEG400; the specific content can be 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, or 75%. The PEG400 serves as the main swelling agent in the composite system, utilizing its polar ether bonds to penetrate the resin crosslinking network.

[0023] The PEG400 composite system provided by this invention includes 8-12% lauryl alcohol polyoxyethylene ether; the specific content can be 8%, 9%, 10%, 11% or 12%. The lauryl alcohol polyoxyethylene ether acts as a synergistic activator, which can reduce the surface tension of the cured phenolic resin, promote the penetration of PEG400, and at the same time form a protective film to prevent the pressure plate from rusting.

[0024] The PEG400 composite system provided by this invention includes 5-8% hydroxyapatite nanorods, specifically 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, or 8%. The hydroxyapatite nanorods act as nanocatalysts, with their surface hydroxyl groups forming hydrogen bonds with the hydroxyl groups of the phenolic resin, thus weakening cross-linking bonds. In this invention, the hydroxyapatite nanorods have a diameter of 50-80 nm, a length of 100-200 nm, and a surface hydroxyl content ≥4.5 mmol / g, enabling them to form hydrogen bonds with the phenolic resin.

[0025] This invention enhances the swelling efficiency of phenolic resin through the synergistic effect of the above-mentioned nanocatalyst and the surface-active component lauryl alcohol polyoxyethylene ether.

[0026] The PEG400 composite system provided by this invention includes a 2-3% pH buffer system, specifically at concentrations of 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3.0%. The pH buffer system prevents acid corrosion of the pressure plate while optimizing the swelling environment; the pH value of the pH buffer system is 6.5-7.0. The preferred pH buffer system is citrate-triethanolamine.

[0027] The PEG400 composite system provided by this invention includes 5-12% of a phase change temperature control agent, specifically 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12%. The phase change temperature control agent is selected from disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O). This invention utilizes the 40℃ phase change endothermic characteristic of disodium hydrogen phosphate dodecahydrate to control the local temperature ≤60℃, preventing overheating and deformation of the pressure plate.

[0028] In a specific embodiment, the PEG400 composite system comprises the following components by mass fraction: 70% PEG400, 10% AEO-9, 6% HA nanorods, 2% citric acid-triethanolamine (pH 6.8) and 12% Na2HPO4·12H2O.

[0029] The PEG400 composite system provided by this invention can effectively remove the cured phenolic resin on the surface of the hot press platen, and achieves the three-in-one technical effect of rapid softening, non-destructive removal and surface protection.

[0030] This invention provides a method for softening and removing cured phenolic resin, comprising the following steps:

[0031] The residual cured phenolic resin on the surface of the pressure plate is blasted with dry ice to obtain pretreated cured phenolic resin.

[0032] The PEG400 composite system described in the above technical solution is electromagnetically atomized on the surface of the pretreated and cured phenolic resin, followed by pulsed ultrasonic-infrared radiation synergistic treatment, and then ultra-high pressure water jet supplemented with soft ceramic abrasive to peel off the softened phenolic resin.

[0033] This invention uses dry ice blasting to remove residual cured phenolic resin from the surface of a pressure plate, resulting in pretreated cured phenolic resin. The dry ice blasting temperature is -78℃, and the pressure is 0.5–0.8 MPa. Dry ice blasting embrittles the surface of the cured phenolic resin, creating microcracks with a width of 5–10 μm. The PEG400 composite system is then uniformly sprayed using an electromagnetic atomization device, with a particle size of 10–20 μm. The amount of electromagnetic atomization used is 1.5–2 times the mass of the residual cured phenolic resin. The pressure plate is preferably a 45# steel plate. The thickness of the residual cured phenolic resin is 0.1–2 mm.

[0034] The pulse interval of the pulsed ultrasound in this invention is 100–200 ms, and the surface temperature of the pressure plate is controlled to be ≤60℃. This invention utilizes the cavitation effect to accelerate resin swelling. The frequency of the pulsed ultrasound is 24–26 kHz, and the power density is 0.55–0.65 W / cm³. 2 ;

[0035] In this invention, the infrared radiation used has a wavelength of 2–3 μm and a power density of 480–510 W / cm². 2 The infrared radiation is applied using an intermittent heating method, with a heating-pause time ratio of 3:0.9 to 1.1, preferably 3:1. In a specific embodiment, the intermittent heating time is 30s and the pause time is 10s. The above heating ensures that the local temperature of the resin is ≤60℃, preferably 55 to 60℃, which promotes PEG diffusion.

[0036] In this invention, the pulsed ultrasound-infrared radiation synergistic processing time is 8 to 10 minutes, specifically 8 minutes, 9 minutes, or 10 minutes.

[0037] This invention utilizes ultra-high pressure water jets supplemented with soft ceramic abrasives to exfoliate softened phenolic resin. The ultra-high pressure water jet has a pressure of 80–100 MPa, specifically 80 MPa, 85 MPa, 90 MPa, 95 MPa, or 100 MPa; a jet angle of 25–30°, specifically 25°, 26°, 27°, 28°, 29°, or 30°; and a temperature of 35–40°C, specifically 35°, 36°, 37°, 38°, 39°, or 40°. The soft ceramic abrasive has a particle size of 50–100 μm. In a specific embodiment, the soft ceramic abrasive is Al2O3 ceramic abrasive with a particle size of 80 μm. This invention avoids damage to the metal surface of the pressure plate by controlling the ultra-high pressure water jet and the soft ceramic abrasive.

[0038] The pressure plate online cleaning module of this invention includes an integrated atomizing nozzle, an ultrasonic transducer (built-in), and an infrared heating plate. It achieves an automated "embrittlement-swelling-peeling" process through PLC control, shortening the cleaning cycle to 15-20 minutes. Preferably, the cleaning solution generated from softening and removing cured phenolic resin is recycled using a recovery system; more preferably, membrane distillation technology is used to recover PEG400, with a distillation temperature of 60℃ and a vacuum degree of -0.09MPa. The recovery rate is ≥92%, and the recycling cost is reduced by 40%.

[0039] This invention solves the efficiency and surface protection problems in the application of industrial pressure plates in the prior art by combining the PEG400 composite system with the above-mentioned process.

[0040] The present invention has the following technical advantages:

[0041] (1) Efficiency innovation: The composite system reduces the softening time of a 1mm thick resin layer from 45 minutes for traditional PEG400 to 8 minutes through the triple action of "nanocatalysis-ultrasonic cavitation-infrared thermal shock".

[0042] (2) Surface protection: The nanoscale protective film (20-30nm thick) formed by AEO-9 can prevent the pressure plate from rusting, while the soft abrasive technology of ultra-high pressure water jet avoids damage to the metal surface.

[0043] (3) Intelligent and low energy consumption: Pulse heating and phase change temperature control technology reduce energy consumption by 55% compared with traditional continuous heating, and the online cleaning module achieves seamless connection between "production and cleaning";

[0044] (4) Green recycling: The cleaning fluid recovery system increases the recycling rate of PEG400 to 92%, and reduces the amount of waste liquid discharged per ton of resin from 80L to 6L.

[0045] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of the PEG400 composite system and the method for softening and removing cured phenolic resin provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1: Resin Removal from a No. 45 Steel Plate

[0047] The PEG400 composite system composition is as follows: PEG400 70%, AEO-9 10%, HA nanorods 6%, citric acid-triethanolamine (pH 6.8) 2%, Na2HPO4·12H2O 12%;

[0048] Operating steps:

[0049] 1. Dry ice blasting pretreatment was performed on the 1mm thick cured resin layer on the single-layer press plate under the following conditions: temperature -78℃, pressure 0.8MPa, time 1 minute;

[0050] 2. Electromagnetic atomization spraying of the above PEG400 composite system: the dosage is 1.8 times the resin mass, and the electromagnetic atomization nozzle flow rate is 45 mL / min;

[0051] 3. Turn on 25kHz pulsed ultrasound (0.6W / cm). 2 (pulse interval 200ms) and infrared radiation (2.5μm wavelength, 500W / m) 2 Heat for 30 seconds / pause for 10 seconds, for a total of 10 minutes;

[0052] 4. Ultra-high pressure water jet (90MPa, 40℃) combined with Al2O3 abrasive (particle size 80μm) for jet peeling.

[0053] 5. After each of the three pressing cycles, the hot press automatically starts the online cleaning program (18 minutes / cycle) to continuously remove 1mm thick resin residue.

[0054] Experimental results data: Resin removal rate 99.8%, platen surface roughness R a =1.4μm, no rust was observed after 240 hours of salt spray testing following cleaning. The cleaning efficiency is 3.5 times higher than that of the patented CN109439301A, and energy consumption is reduced by 58%.

[0055] Example 2: Online Cleaning in Continuous Production

[0056] 1. Dry ice blasting pretreatment was performed on the 0.5mm thick cured resin layer on the platen of the multi-layer continuous hot press. The conditions were: temperature -78℃, pressure 0.6MPa, time 0.6 minutes.

[0057] 2. Electromagnetic atomization spraying of the above PEG400 composite system: the dosage is 1 times the mass of the resin, and the flow rate of the electromagnetic atomization nozzle is 40 mL / min;

[0058] 3. Turn on 25kHz pulsed ultrasound (0.6W / cm2, pulse interval 150ms) and infrared radiation (2.5μm wavelength, 490W / cm2, heating for 30s / pause for 10s) for 6 minutes;

[0059] 4. Ultra-high pressure water jet (85MPa, 35℃) combined with Al2O3 abrasive (particle size 60μm) for jet peeling.

[0060] 5. After each 3 pressing cycles, the hot press automatically starts the online cleaning program (15 minutes / cycle) to continuously remove resin residue of 0.3-0.5mm thickness.

[0061] Experimental results data: Traditional shutdown cleaning (CN109439301A method) requires 60 minutes per cycle, and the product defect rate (dents) is 3.2% after each cleaning. The method provided by this invention reduces the defect rate to 0.5% and increases production capacity by 25%.

[0062] Comparative Example 1

[0063] Composite system composition: PEG400 80%, hydroxyapatite nanorods 6%, citrate-triethanolamine (pH 6.8) 2%, disodium hydrogen phosphate dodecahydrate 12%.

[0064] Operating steps:

[0065] 1. Dry ice blasting pretreatment was performed on the 1mm thick cured resin layer on the single-layer press plate under the following conditions: temperature -78℃, pressure 0.8MPa, time 1 minute;

[0066] 2. Electromagnetic atomization spraying of the above PEG400 composite system: the dosage is 1.8 times the resin mass, and the electromagnetic atomization nozzle flow rate is 45 mL / min;

[0067] 3. Turn on 25kHz pulsed ultrasound (0.6W / cm). 2 (pulse interval 200ms) and infrared radiation (2.5μm wavelength, 500W / m) 2 Heat for 30 seconds / pause for 10 seconds, for a total of 10 minutes;

[0068] 4. Ultra-high pressure water jet (90MPa, 40℃) combined with Al2O3 abrasive (particle size 80μm) for jet peeling.

[0069] 5. After each of the three pressing cycles, the hot press automatically starts the online cleaning program (18 minutes / cycle) to continuously remove 1mm thick resin residue.

[0070] Experimental results data: Resin removal rate 72%, platen surface roughness R a =2.9μm. After cleaning, a large area of ​​rust spots appeared in the salt spray test after 240 hours. The removal efficiency decreased by 28% compared with Example 1. Due to the lack of the penetration promoting effect of lauryl alcohol polyoxyethylene ether, only the surface 0.3mm of the 1mm thick resin layer was softened. In addition, the lack of a nano protective film significantly increased the risk of rust on the pressure plate.

[0071] Comparative Example 2

[0072] Composite system formulation: PEG400 76%, lauryl alcohol polyoxyethylene ether (AEO-9) 10%, citric acid-triethanolamine (pH 6.8) 2%, disodium hydrogen phosphate dodecahydrate 12%.

[0073] Operating steps:

[0074] 1. Dry ice blasting pretreatment was performed on the 1mm thick cured resin layer on the single-layer press plate under the following conditions: temperature -78℃, pressure 0.8MPa, time 1 minute;

[0075] 2. Electromagnetic atomization spraying of the above PEG400 composite system: the dosage is 1.8 times the resin mass, and the electromagnetic atomization nozzle flow rate is 45 mL / min;

[0076] 3. Turn on 25kHz pulsed ultrasound (0.6W / cm). 2 (pulse interval 200ms) and infrared radiation (2.5μm wavelength, 500W / m) 2 Heat for 30 seconds / pause for 10 seconds, for a total of 10 minutes;

[0077] 4. Ultra-high pressure water jet (90MPa, 40℃) combined with Al2O3 abrasive (80μm particle size) for jet peeling.

[0078] 5. After each of the three pressing cycles, the hot press automatically starts the online cleaning program (18 minutes / cycle) to continuously remove 1mm thick resin residue.

[0079] Experimental results: Resin removal rate 75%, platen surface roughness Ra = 2.2 μm, no obvious rust spots after 240 hours of salt spray test after cleaning (because the AEO-9 protective film is still present), but only 0.5 mm of the 1 mm thick resin layer softened, and the swelling efficiency decreased by 50% compared with Example 1.

[0080] Comparative Example 3

[0081] Composite system composition: 70% PEG400, 10% sodium dodecyl sulfate (SDS, replacing AEO-9), 6% hydroxyapatite nanorods, 2% citrate-triethanolamine (pH 6.8), and 12% disodium hydrogen phosphate dodecahydrate.

[0082] Operating steps:

[0083] 1. Dry ice blasting pretreatment was performed on the 1mm thick cured resin layer on the single-layer press plate under the following conditions: temperature -78℃, pressure 0.8MPa, time 1 minute;

[0084] 2. Electromagnetic atomization spraying of the above PEG400 composite system: the dosage is 1.8 times the resin mass, and the electromagnetic atomization nozzle flow rate is 45 mL / min;

[0085] 3. Turn on 25kHz pulsed ultrasound (0.6W / cm). 2 (pulse interval 200ms) and infrared radiation (2.5μm wavelength, 500W / m) 2 Heat for 30 seconds / pause for 10 seconds, for a total of 10 minutes;

[0086] 4. Ultra-high pressure water jet (90MPa, 40℃) combined with Al2O3 abrasive (particle size 80μm) for jet peeling.

[0087] 5. After each of the three pressing cycles, the hot press automatically starts the online cleaning program (18 minutes / cycle) to continuously remove 1mm thick resin residue.

[0088] Experimental results: Resin removal rate: 82% (99.8% in Example 1); Platen surface roughness: R a = 2.5μm (1.4μm in Example 1); Salt spray test (240 hours): localized rust appeared (no rust in Example 1); Time for complete softening of 1mm thick resin: 15 minutes (10 minutes in Example 1).

[0089] As can be seen from the above embodiments, the present invention provides a PEG400 composite system, comprising the following components by mass fraction: 65-75% PEG400, 8-12% lauryl alcohol polyoxyethylene ether, 5-8% hydroxyapatite nanorods, 2-3% pH buffer system, and 5-12% phase change temperature control agent. The present invention, by employing the PEG400 composite system comprising the above components under the above-described cleaning process, removes the cured phenolic resin from the hot press platen, achieving a three-in-one technical effect of rapid softening, non-destructive removal, and surface protection. Experimental results show that the resin removal rate is 99.8%, and the surface roughness R of the platen is [not specified]. a =1.4μm, no rust was observed after 240 hours of salt spray testing following cleaning.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A PEG400 composite system, comprising the following components by mass fraction: 65-75% PEG400, 8-12% lauryl alcohol polyoxyethylene ether, 5-8% hydroxyapatite nanorods, 2-3% pH buffer system and 5-12% phase change temperature control agent.

2. The PEG400 composite system according to claim 1, characterized in that, The hydroxyapatite nanorods have a diameter of 50–80 nm and a length of 100–200 nm.

3. The PEG400 composite system according to claim 1, characterized in that, The pH buffer system is citrate-triethanolamine.

4. The PEG400 composite system according to claim 3, characterized in that, The pH value of the pH buffer system is 6.5 to 7.

0.

5. The PEG400 composite system according to claim 1, characterized in that, The phase change temperature control agent is selected from disodium hydrogen phosphate dodecahydrate.

6. A method for softening and removing cured phenolic resin, comprising the following steps: The residual cured phenolic resin on the surface of the pressure plate is blasted with dry ice to obtain pretreated cured phenolic resin. The PEG400 composite system described in any one of claims 1 to 5 is electromagnetically atomized on the surface of pretreated and cured phenolic resin, followed by pulsed ultrasonic-infrared radiation synergistic treatment, and then ultra-high pressure water jet supplemented with soft ceramic abrasive to peel off the softened phenolic resin.

7. The method according to claim 6, characterized in that, The pulse interval of the pulsed ultrasound is 100-200ms, the heating-pause time ratio of infrared radiation is 3:0.9-1.1, and the surface temperature of the pressure plate is controlled to be ≤60℃.

8. The method according to claim 7, characterized in that, The frequency of pulsed ultrasound is 24–26 kHz, and the power density is 0.55–0.65 W / cm². 2 ; The infrared radiation used has a wavelength of 2–3 μm and a power density of 480–510 W / cm². 2 .

9. The method according to claim 8, characterized in that, The collaborative processing time is 8 to 10 minutes.

10. The method according to claim 6, characterized in that, The ultra-high pressure water jet has a pressure of 80-100 MPa, a spray angle of 25-30°, and a temperature of 35-40°. The particle size of soft ceramic abrasive is 50–100 μm.