HP-RTM external release agent and preparation method thereof

Abstract

The HP-RTM external release agent comprises a bottom layer strengthening phase and a middle surface layer functional phase, the thickness of the bottom layer strengthening phase is 0.2-5 [mu] m; the total thickness of the middle surface layer functional phase is 1-20 microns; the bottom layer strengthening phase is prepared from the following components in percentage by weight: 5 to 15 percent of vinyl silicon resin, 2 to 6 percent of hydrogen-containing silicon resin, 70 to 88 percent of hydrocarbon solvent, 0.2 to 1.5 percent of nano silicon dioxide, 0.3 to 1.5 percent of fluorinated flatting agent and 5 to 60 ppm of platinum catalyst; the middle surface layer functional phase comprises 10-40% of hydroxyl silicone oil; 3-15% of a silane cross-linking agent; 8-20% of modified silicone oil; 3-10% of a nonionic emulsifier; 20 to 60% of deionized water; 0.5 to 5% of nano silicon dioxide; and 0.01-0.5% of an organic tin catalyst. The release agent system can improve the anti-scouring capacity of a film layer, improve the self-repairing performance, achieve the scratch repairing rate of 80% or above, improve the stability of the film layer and prolong the service life of the film layer by three times or above.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, specifically to an external release agent suitable for high pressure resin transfer molding (HP-RTM) process and its preparation method. Background Technology

[0002] The HP-RTM process rapidly injects resin into a sealed mold under high pressure (120-180 bar), combined with high-temperature curing (80-120℃) to achieve efficient molding. It boasts advantages such as short molding cycles, high dimensional accuracy, high glass fiber content, and low porosity. It has been successfully applied to the industrial production of key components such as automotive bumpers, roof reinforcement panels, and new energy battery box covers. However, the high-temperature and high-pressure conditions of the HP-RTM process place stringent requirements on the mold release agent system. Firstly, there is the requirement for high-pressure penetration protection. When resin is injected into the cavity at a pressure of 120-180 bar, the mold release agent must possess sufficient strength and elastic modulus to resist fluid shear forces; otherwise, resin will penetrate the mold release agent layer, leading to adhesion or the formation of dry spots on the product surface. Secondly, due to the rapid production cycle, the mold release agent needs to complete the uniform film construction within a short period to ensure full coverage of the mold surface. Thirdly, with the increase in re-spraying times, the mold release agent needs to maintain continuous film stability to minimize the rate of fouling and reduce the frequency of mold cleaning.

[0003] With the increasing demand for lightweight vehicles and the widespread application of HP-RTM technology in related fields, mold release agents are undergoing continuous technological improvements. However, existing mold release agents struggle to meet the following needs: complex structural parts or thin-walled large parts are difficult to demold completely due to high demolding forces, or product deformation is caused by high demolding stress; localized demolding difficulties arise due to localized damage to the film layer caused by demolding stress or external forces, and re-spraying mold release agent can easily lead to mold release agent residue, color difference, uneven film formation, and rough film surface, affecting subsequent processes; with the increase in the number of re-spraying, the problems of mold release agent color difference, film layer damage, and mold release agent scale accumulation become serious, requiring the cleaning of mold release agent scale after 60-100 molds of continuous operation, which greatly affects production efficiency.

[0004] CN113527767A discloses a method for preparing a magnetic internal release agent, comprising the following steps: 1) preparing magnetic material particles: preferably, the magnetic material is a ferrite magnetic material; 2) adding the magnetic material particles to a mixed solution of distilled water and ethanol, performing thorough ultrasonic dispersion, and adding, dropwise, compounds containing amino and alkoxy groups under nitrogen protection, stirring thoroughly until the reaction is complete, washing, and freeze-drying to obtain the amino-modified magnetic material; 3) adding the amino-modified magnetic material to anhydrous ethanol, performing thorough ultrasonic dispersion, adding an activator, stirring thoroughly, and adding, dropwise, a hydroxyl-terminated polysiloxane release agent graft under stirring, stirring until the reaction is complete, washing, and freeze-drying to obtain the magnetic internal release agent. The release agent exhibits excellent continuous release performance, which can significantly improve the production efficiency of composite materials.

[0005] CN107599250A discloses a silicone-based mold release agent for automotive seat cushions. This silicone-based mold release agent includes a first mold release agent and a second mold release agent. The first mold release agent comprises the following components by weight percentage: 5% dimethyl silicone oil, 5% silicone resin, 0.05% wetting agent BYK306, 0.02% adhesion promoter BYK4509, 0.05% odor masking agent, 50% dichloromethane, and 39.88% No. 120 solvent oil. The second mold release agent comprises the following components by weight percentage: 5% dimethyl silicone oil, 5% silicone resin, 0.01% wetting agent, 0.1% adhesion promoter, 0.05% odor masking agent, 50% dichloromethane, and 39.88% No. 120 solvent oil. The mold release agent produced in this manner has stronger demolding ability, is inexpensive, and is easy to manufacture. Summary of the Invention

[0006] This invention utilizes two release agents in combination to form an external release agent system suitable for the epoxy resin HP-RTM process. This system comprises a bottom reinforcing phase and a middle / surface functional phase. The bottom and middle / surface phases work synergistically to reduce the deformation of the product caused by release force and demolding stress, thereby reducing release agent accumulation and the frequency of mold clearing. The bottom reinforcing phase ensures film strength, while the middle / surface functional phase reduces release force while imparting molecular-level self-healing properties to the system, compensating for localized film-forming defects.

[0007] This invention provides a layered film-forming mechanism design. The bottom reinforcing phase uses a platinum catalytic system of vinyl silicone resin and hydrogen-containing silicone resin to construct a three-dimensional cross-linked network structure on the mold surface through hydrosilylation reaction, forming a dense bottom film layer with a thickness of 0.5~2μm, which can better resist resin penetration under high pressure. The middle and surface functional phases form a flexible layer on the bottom film through polycondensation reaction, with a dynamic contact angle >130°. Modified silicone oil (such as vinyl silicone oil and amino silicone oil) endows the system with self-healing properties, which can compensate for local film-forming defects and inhibit the decay of demolding performance.

[0008] The release agent described in this invention exhibits a multiphase synergistic effect. Through the gradient combination of the bottom / middle-surface release agents, erosion resistance is improved, and the bottom cross-linked network remains intact under 180 bar pressure (conventional release agents face the risk of film breakage at 100 bar). The balanced three phases ensure film stability without sacrificing release performance, reducing release agent fouling and minimizing mold cleaning frequency. The modified silicone oil in the middle-surface layer undergoes reversible bonding with epoxy groups, achieving dynamic repair at the molecular level.

[0009] This invention discloses an HP-RTM external release agent system, its preparation process, and its spraying process. This system is suitable for the HP-RTM molding process of epoxy resin.

[0010] An HP-RTM external release agent comprises a bottom reinforcing phase and a middle and surface functional phase; the thickness of the bottom reinforcing phase is 0.2~5μm; the total thickness of the middle and surface functional phase is 1-20μm; the bottom reinforcing phase comprises 5~15% vinyl silicone resin, 2~6% hydrogen-containing silicone resin, 70~88% hydrocarbon solvent, 0.2~1.5% nano silica, 0.3~1.5% fluorinated leveling agent, and 5~60ppm platinum-based catalyst; the middle and surface functional phase comprises 10~40% hydroxyl silicone oil; 3~15% silane crosslinking agent; 8~20% modified silicone oil; 3~10% nonionic emulsifier; 20~60% deionized water; 0.5~5% nano silica; and 0.01~0.5% organotin catalyst.

[0011] The bottom reinforcing phase is a dense layer obtained through the addition crosslinking reaction of vinyl silicone resin and hydrogen-containing silicone resin, ensuring the film's density and erosion resistance. In the lower part of the middle surface functional phase, a de-alcoholization reaction occurs between hydroxyl silicone oil and silane crosslinking agent. Simultaneously, the hydroxyl groups react with residual silane-hydrogen bonds in the bottom layer, enhancing interlayer bonding. The upper part of the middle surface functional phase is mainly composed of modified silicone oil, increasing lubricity. Furthermore, the reversible reaction between specific groups and epoxy groups gives the film excellent self-healing properties.

[0012] Preferably, the bottom mold release agent includes 8-12% vinyl silicone resin, 3-5% hydrogen-containing silicone resin, 75-85% hydrocarbon solvent, 0.5-1% nano silica, 0.5-1% fluorinated leveling agent, and 10-50 ppm platinum-based catalyst.

[0013] Preferably, the middle surface release agent includes 20-30% hydroxyl silicone oil, 5-10% silane crosslinking agent, 10-18% modified silicone oil, 4-8% nonionic emulsifier, 30-50% deionized water, 1-3% nano silica, and 0.1-0.3% organotin catalyst.

[0014] The vinyl silicone resin is one or more of terminal vinyl silicone resin, side-chain vinyl silicone resin, and MQ vinyl silicone resin; the hydrogen-containing silicone resin is one or more of branched hydrogen-containing silicone resin and MQ hydrogen-containing silicone resin; the alkane solvent is one or more of alkanes, alkenes, cycloalkanes, and aromatics with a carbon chain of 3-12, preferably one or more of isohexane, cyclohexane, isopropane, and isobutane; the silane crosslinking agent is one or more of methyltriethylsilane and tetramethylsilane; the modified silicone oil is one or more of alkyl silicone oil, vinyl silicone oil, and amino silicone oil; the hydroxyl silicone oil is one of terminal hydroxyl polydimethylsiloxane and side-chain hydroxyl silicone oil; the average particle size of the nano-silica is 10-100 nm; the platinum catalyst is one or more of platinum / alumina, platinum / silica, platinum chloric acid, and platinum black, and the amount of platinum catalyst used is calculated based on the platinum content; the organotin is one or more of dibutyltin diacetate and stannous octoate.

[0015] The preparation method of the HP-RTM external release agent includes the following steps: (1) Preparation of bottom layer release agent: add isoparaffin solvent to reaction vessel, control temperature at 25±5℃, stir and mix evenly, slowly add vinyl resin, continue stirring until completely dissolved, heat hydrogen-based silicone resin and fluorinated leveling agent, raise temperature to 40℃-50℃, continue high-speed stirring and add nano silica and platinum catalyst to cool to room temperature, filter to obtain bottom layer release agent. (2) Preparation process of intermediate surface release agent: Silicone oil phase premixing, hydroxyl silicone oil, modified silicone oil, silane crosslinking agent and emulsifier are mixed and heated to 60~70℃; deionized water is added and dispersed evenly, and the emulsion particle size is controlled to be 80-150nm; nano silica is added, the temperature is lowered to below 40℃, organotin catalyst is added, and the pH value of the emulsion is adjusted to 5.5~6.5; after filtration, the intermediate surface release agent is obtained.

[0016] The processes described in steps (1) and (2) must be carried out under stirring conditions, and the stirring speed is 100-500 rpm; the high-speed stirring speed described in step (1) is 1000-3000 rpm, and preferably, the stirring process is carried out under ultrasonic conditions.

[0017] The deionized water in step (2) is added multiple times, preferably in 4-8 times, with an interval of 3-10 minutes between each addition; the addition of deionized water is carried out in a high-pressure homogenizer with a working pressure of 80-120 MPa, and the process is repeated 3-5 times.

[0018] A method for using HP-RTM external release agent includes the following steps: (a) Clean the mold surface and heat the mold to 80~110℃; (b) Add the base release agent to the low-pressure high-flow (HVLP) spray gun and spray two coats for the first time, with a spray interval of 3-5 minutes; (c) Add the intermediate surface release agent to the spray gun and spray it once on the basis of the bottom release agent. After spraying, keep it warm for 2-3 minutes before production.

[0019] Preferably, during the use of the HP-RTM external release agent, depending on the demolding situation, a bottom layer release agent is sprayed every 40 to 50 molds, and a middle surface layer release agent is sprayed every 10 to 15 molds.

[0020] Preferably, the cleaning process in step (a) uses organic solvents and / or cleaning agents, including ketones, ethers, and alcohols, preferably one of acetone and ethanol; the nozzle diameter of the spray gun in step (b) is 1.2-2 mm, the pressure is 0.2-0.5 MPa, and the distance is 25-35 cm; the moving path of the spray gun in step (c) is S-shaped, with each path overlapping the previous spraying path by 1 / 3-1 / 2.

[0021] The demolding stress during the HP-RTM process significantly affects the product's deformation. When the product is a large, thin-walled part without reinforcing ribs, the contour of the large surface is even more sensitive to this demolding stress. With other molding parameters unchanged, there is a clear correlation between the magnitude of the demolding stress and the maximum deformation of the product's contour. In actual production, the ease of demolding is often subjectively judged, making it difficult to directly measure the demolding force. Testing the product's contour deformation can indirectly reflect the demolding effect, quantitatively describe the demolding state, and is also a more accurate evaluation method for actual production needs. The specific method involves sequentially cooling and laser-cutting the molded product, then placing it on a dedicated testing fixture. The positioning pins on the fixture are aligned with the positioning holes of the battery pack, inserted, and locked to ensure the relative position of the battery pack is fixed. After zeroing the dial indicator, it is placed on the testing fixture, and moved to different positions on the large surface of the product. The deformation at each position can be read from the dial indicator.

[0022] After the product has cooled and set, use a dyne pen with a suitable surface energy range (22~44mN / m) to measure the surface dyne value. Start testing from a low tension value and gradually increase until a critical value is found. The specific operating procedure is as follows: Hold the dyne pen and draw a continuous line 2~3cm long across the surface at approximately a 45° angle. Repeat the drawing on different areas of the sample surface to avoid errors caused by surface unevenness. If the line remains continuous, without shrinking or breaking within 2 seconds, the surface energy is "≥ the marked value of the dyne pen". If the line shrinks, breaks, or gathers into droplets within 2 seconds, the surface energy is "< the marked value of the dyne pen". If a dyne pen test at a certain tension value fails while a test at an adjacent higher tension value fails, the surface energy is between the two.

[0023] Unless otherwise specified, all percentages mentioned in this application are mass percentages.

[0024] The bottom reinforcing phase uses vinyl silicone resin and hydrogen-containing silicone resin, which are used to construct a stable and dense three-dimensional network structure on the mold through hydrogenation catalysis. The bottom phase can resist resin penetration under high pressure. Compared with the network structure formed by condensation, the film is dense and stable, and only needs to be sprayed after 40-50 molds. The bottom, middle and top layers work together to ensure the stability of the film while reducing the deformation of the product caused by demolding stress, reducing the accumulation of mold release agent and the frequency of mold cleaning.

[0025] Modified silicone oil is introduced into the surface layer. Specific functional groups (such as -NH2, -NHR) reversibly bind with residual epoxy groups (three-membered cyclic ethers) on the product surface through dynamic covalent bonds, achieving molecular-level micro-repair. Specifically, when high-pressure injection or demolding stress causes microcracks (width <10μm) in the film layer, the surface tension gradient in the damaged area drives amino silicone oil molecules to diffuse towards the cracks, reacting with the epoxy groups exposed on the crack surface to form hydroxylamine intermediates. These intermediates further condense with adjacent amino or hydroxyl groups to form a cross-linked network. Driven by thermodynamics, the dynamic bonds rearrange, filling the crack voids until a continuous film layer is formed, restoring the film's integrity.

[0026] The beneficial technical effects of this invention are as follows: Compared with traditional release agents, the release agent system provided by this patent can improve the erosion resistance of the film layer by 3 times; improve the self-healing performance, achieve a scratch repair rate of more than 80%, improve the stability of the film layer, and extend the life of the film layer by 3 times; and can continuously produce 150 to 200 molds for mold cleaning, increasing production efficiency by 15%. Detailed Implementation

[0027] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0028] The present invention will now be described in further detail with reference to specific embodiments.

[0029] Example 1 Example 1: Methyl vinyl MQ silicone resin A, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 c, a+b / c=0.8, vinyl content 0.1mol / 100g, Methyl vinyl MQ silicone resin B, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 ] c a+b / c=1.4, vinyl content 0.8mol / 100g Methyl hydrogen-containing MQ silicone resin, [(CH3)2HSiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 ] c a+b / c=1.2~1.5, hydrogen content 0.65~0.75mol / 100g Preparation process of the bottom layer release agent: Add 480g of cyclohexane to the reactor, control the temperature at 25±5℃, stir and mix evenly at 300rpm. Slowly add 70g of methyl vinyl MQ silicone resin A and 30g of methyl vinyl MQ silicone resin B, and continue stirring for 30min until completely dissolved. Add 50g of methyl hydrogen-containing MQ silicone resin to 250g of cyclohexane for pre-dilutement, and then slowly add it to the main system to avoid excessively high local concentrations. Slowly add 10g of fluorinated leveling agent, heat to 40℃, and stir for 1h until molecular-level dispersion. Disperse 10g of nano-SiO2 in 90g of cyclohexane using an ultrasonicator for 30min to form a stable slurry, and slowly add it to the main system. Shear disperse at 2000rpm for 15min to ensure no agglomeration. Dilute 0.1g of platinum catalyst in 10g of cyclohexane solvent and sonicate for 10min to prevent agglomeration. After the nano-silica is dispersed and cooled to below 30°C, slowly add 0.5g of catalyst dilution solution and stir at low speed (200rpm) for 10min to ensure uniform dispersion. Filter through a 5μm filter cartridge and fill into a light-proof, airtight container. Store at ≤25°C.

[0030] Preparation process of intermediate surface release agent: Mix 300g hydroxyl silicone oil, 100g methyltriethylsilane, 160g vinyl silicone oil, and 60g emulsifier, heat to 60~70℃, stir for 40 minutes (800~1000rpm) until completely homogenized, emulsified and dispersed, slowly add 500g of deionized water in 4 portions, 5 minutes apart each time, to form a crude emulsion, and process it three times using a high-pressure homogenizer (80~120MPa) to control the emulsion particle size to 80-150nm; add 20g nano SiO2, ultrasonically disperse for 30min (500W power, 20kHz frequency), cool to below 40℃, add organotin catalyst, and stir at low speed for 15 minutes (200rpm); adjust the pH of the emulsion to 5.5~6.5 with acetic acid; filter through a 5μm filter, fill into a light-proof container, and store at 5~30℃.

[0031] Spraying Process: Clean the mold surface (verify the mold is a two-cavity product, approximately 1680×1250×25mm) thoroughly with a cleaning agent (acetone, silver crystal cleaner, etc.) to ensure no residue remains; preheat the mold to 80~110℃; add the base layer release agent to a low-pressure high-flow (HVLP) spray gun (1.2~2.0mm nozzle, 0.3MPa air pressure), spray at a distance of 25~35cm, maintaining a 90° vertical spray angle as much as possible, with a reciprocating speed of 0.5m / s. After cleaning the mold, apply two coats initially, with a 3~5min interval between coats. Add the intermediate layer release agent to a 2.0mm nozzle spray gun, adjusting the spray pattern (spray fan) so that the fan width is 30~40cm when the spray gun is 30~40cm away from the mold surface, maintaining a 90° vertical spray angle as much as possible. The moving speed is approximately 0.5 m / s, and the moving path is S-shaped. Each layer of release agent should overlap the previous layer by 1 / 3 to prevent missed areas. One coat is sufficient on top of the base layer of release agent. After spraying, keep warm for 2-3 minutes before production. There are 166 coats that do not require thorough cleaning and recoating.

[0032] Example 2: Methyl vinyl MQ silicone resin A, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 c, a+b / c=0.8, vinyl content 0.1mol / 100g, Methyl vinyl MQ silicone resin B, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 ] ca+b / c=1.4, vinyl content 0.8mol / 100g Methyl hydrogen-containing MQ silicone resin, [(CH3)2HSiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 a+b / c=1.2~1.5, hydrogen content 0.65~0.75mol / 100g Preparation process of the bottom layer release agent: Add 480g of cyclohexane to the reactor, control the temperature at 25±5℃, stir and mix evenly at 300rpm. Slowly add 70g of methyl vinyl MQ silicone resin A and 30g of methyl vinyl MQ silicone resin B, and continue stirring for 30min until completely dissolved. Add 50g of methyl hydrogen-containing MQ silicone resin to 250g of cyclohexane for pre-dilutement, and then slowly add it to the main system to avoid excessively high local concentrations. Slowly add 10g of fluorinated leveling agent, heat to 40℃, and stir for 1h until molecular-level dispersion. Disperse 10g of nano-SiO2 in 90g of cyclohexane using an ultrasonicator for 30min to form a stable slurry, and slowly add it to the main system. Shear disperse at 2000rpm for 15min to ensure no agglomeration. Dilute 0.1g of platinum catalyst in 10g of cyclohexane solvent and sonicate for 10min to prevent agglomeration. After the nano-silica is dispersed and cooled to below 30°C, slowly add 0.5g of catalyst dilution solution and stir at low speed (200rpm) for 10min to ensure uniform dispersion. Filter through a 5μm filter cartridge and fill into a light-proof, airtight container. Store at ≤25°C.

[0033] Preparation process of intermediate surface release agent: Mix 300g hydroxyl silicone oil, 100g methyltriethylsilane, 80g vinyl silicone oil, 80g amino silicone oil, and 60g emulsifier. Heat to 60~70℃ and stir for 40 minutes (800~1000rpm) until completely homogenized and dispersed. Add 500g of deionized water slowly in 4 portions, with an interval of 5 minutes between each addition, to form a coarse emulsion. Circulate the emulsion three times using a high-pressure homogenizer (80~120MPa) to control the emulsion particle size to 80-150nm. Add 20g nano-SiO2 and ultrasonically disperse for 30min (500W power, 20kHz frequency). Cool to below 40℃, add organotin catalyst, and stir at low speed for 15 minutes (200rpm). Adjust the pH of the emulsion to 5.5~6.5 with acetic acid. Filter through a 5μm filter and fill into a light-proof container. Store at 5~30℃.

[0034] Spraying Process: Clean the mold surface (verify the mold is a two-cavity product, approximately 1680×1250×25mm) thoroughly with a cleaning agent (acetone, silver crystal cleaner, etc.) to ensure no residue remains; preheat the mold to 80~110℃; add the base layer release agent to a low-pressure high-flow (HVLP) spray gun (1.2~2.0mm nozzle, 0.3MPa air pressure), spray at a distance of 25~35cm, maintaining a 90° vertical spray angle as much as possible, with a reciprocating speed of 0.5m / s. After cleaning the mold, apply two coats initially, with a 3~5min interval between coats. Add the intermediate layer release agent to a 2.0mm nozzle spray gun, adjusting the spray pattern (spray fan) so that the fan width is 30~40cm when the spray gun is 30~40cm away from the mold surface, maintaining a 90° vertical spray angle as much as possible. The moving speed is approximately 0.5 m / s, and the moving path is S-shaped. Each layer of release agent should overlap the previous layer by 1 / 3 to prevent missed areas. One coat is sufficient on top of the base layer of release agent. After spraying, keep warm for 2-3 minutes before production. There are 175 applications that do not require thorough cleaning and recoating.

[0035] Example 3: Methyl vinyl MQ silicone resin A, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 c, a+b / c=0.8, vinyl content 0.1mol / 100g, Methyl vinyl MQ silicone resin B, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 ] c a+b / c=1.4, vinyl content 0.8mol / 100g Methyl hydrogen-containing MQ silicone resin, [(CH3)2HSiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 a+b / c=1.2~1.5, hydrogen content 0.65~0.75mol / 100g Preparation process of the bottom layer release agent: Add 480g of cyclohexane to the reactor, control the temperature at 25±5℃, stir and mix evenly at 300rpm. Slowly add 70g of methyl vinyl MQ silicone resin A and 30g of methyl vinyl MQ silicone resin B, and continue stirring for 30min until completely dissolved. Add 50g of methyl hydrogen-containing MQ silicone resin to 250g of cyclohexane for pre-dilutement, and then slowly add it to the main system to avoid excessively high local concentrations. Slowly add 10g of fluorinated leveling agent, heat to 40℃, and stir for 1h until molecular-level dispersion. Disperse 10g of nano-SiO2 in 90g of cyclohexane using an ultrasonicator for 30min to form a stable slurry, and slowly add it to the main system. Shear disperse at 2000rpm for 15min to ensure no agglomeration. Dilute 0.1g of platinum catalyst in 10g of cyclohexane solvent and sonicate for 10min to prevent agglomeration. After the nano-silica is dispersed and cooled to below 30°C, slowly add 0.5g of catalyst dilution solution and stir at low speed (200rpm) for 10min to ensure uniform dispersion. Filter through a 5μm filter cartridge and fill into a light-proof, airtight container. Store at ≤25°C.

[0036] Preparation process of intermediate surface release agent: Mix 300g hydroxyl silicone oil, 100g methyltriethylsilane, 60g vinyl silicone oil, 120g amino silicone oil, and 60g emulsifier. Heat to 60~70℃ and stir for 40 minutes (800~1000rpm) until completely homogenized and dispersed. Add 500g of deionized water slowly in 4 portions, with an interval of 5 minutes between each addition, to form a coarse emulsion. Circulate the emulsion three times using a high-pressure homogenizer (80~120MPa) to control the emulsion particle size to 80-150nm. Add 20g nano-SiO2 and ultrasonically disperse for 30min (500W power, 20kHz frequency). Cool to below 40℃, add organotin catalyst, and stir at low speed for 15 minutes (200rpm). Adjust the pH of the emulsion to 5.5~6.5 with acetic acid. Filter through a 5μm filter and fill into a light-proof container. Store at 5~30℃.

[0037] Spraying Process: Clean the mold surface (verify the mold is a two-cavity product, approximately 1680×1250×25mm) thoroughly with a cleaning agent (acetone, silver crystal cleaner, etc.) to ensure no residue remains; preheat the mold to 80~110℃; add the base layer release agent to a low-pressure high-flow (HVLP) spray gun (1.2~2.0mm nozzle, 0.3MPa air pressure), spray at a distance of 25~35cm, maintaining a 90° vertical spray angle as much as possible, with a reciprocating speed of 0.5m / s. After cleaning the mold, apply two coats initially, with a 3~5min interval between coats. Add the intermediate layer release agent to a 2.0mm nozzle spray gun, adjusting the spray pattern (spray fan) so that the fan width is 30~40cm when the spray gun is 30~40cm away from the mold surface, maintaining a 90° vertical spray angle as much as possible. The moving speed is approximately 0.5 m / s, and the moving path is S-shaped. Each layer of release agent should overlap the previous layer by 1 / 3 to prevent missed areas. One coat is sufficient on top of the base layer of release agent. After spraying, keep warm for 2-3 minutes before production. There are 158 applications that do not require thorough cleaning and recoating.

[0038] Example 4: Methyl vinyl MQ silicone resin A, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 c, a+b / c=0.8, vinyl content 0.1mol / 100g, Methyl vinyl MQ silicone resin B, (CH3)2(CH2=CH)SiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 ] c a+b / c=1.4, vinyl content 0.8mol / 100g Methyl hydrogen-containing MQ silicone resin, [(CH3)2HSiO 1 / 2 ] a [(CH3)3SiO 1 / 2 ] b [SiO 4 / 2 a+b / c=1.2~1.5, hydrogen content 0.65~0.75mol / 100g Preparation process of the bottom layer release agent: Add 480g of cyclohexane to the reactor, control the temperature at 25±5℃, stir and mix evenly at 300rpm. Slowly add 60g of methyl vinyl MQ silicone resin A and 40g of methyl vinyl MQ silicone resin B, and continue stirring for 30min until completely dissolved. Pre-dilute 50g of methyl hydrogen-containing MQ silicone resin in 250g of cyclohexane, and then slowly add it to the main system to avoid excessively high local concentrations. Slowly add 10g of fluorinated leveling agent, heat to 40℃, and stir for 1h until molecular-level dispersion. Disperse 10g of nano-SiO2 in 90g of cyclohexane using an ultrasonicator for 30min to form a stable slurry, and slowly add it to the main system. Shear disperse at 2000rpm for 15min to ensure no agglomeration. Dilute 0.1g of platinum catalyst in 10g of cyclohexane solvent and sonicate for 10min to prevent agglomeration. After the nano-silica is dispersed and cooled to below 30°C, slowly add 0.5g of catalyst dilution solution and stir at low speed (200rpm) for 10min to ensure uniform dispersion. Filter through a 5μm filter cartridge and fill into a light-proof, airtight container. Store at ≤25°C.

[0039] Preparation process of intermediate surface release agent: Mix 300g hydroxyl silicone oil, 100g methyltriethylsilane, 80g vinyl silicone oil, 80g amino silicone oil, and 60g emulsifier. Heat to 60~70℃ and stir for 40 minutes (800~1000rpm) until completely homogenized and dispersed. Add 500g of deionized water slowly in 4 portions, with an interval of 5 minutes between each addition, to form a coarse emulsion. Circulate the emulsion three times using a high-pressure homogenizer (80~120MPa) to control the emulsion particle size to 80-150nm. Add 20g nano-SiO2 and ultrasonically disperse for 30min (500W power, 20kHz frequency). Cool to below 40℃, add organotin catalyst, and stir at low speed for 15 minutes (200rpm). Adjust the pH of the emulsion to 5.5~6.5 with acetic acid. Filter through a 5μm filter and fill into a light-proof container. Store at 5~30℃.

[0040] Spraying Process: Clean the mold surface (verify the mold is a two-cavity product, approximately 1680×1250×25mm) thoroughly with a cleaning agent (acetone, silver crystal cleaner, etc.) to ensure no residue remains; preheat the mold to 80~110℃; add the base layer release agent to a low-pressure high-flow (HVLP) spray gun (1.2~2.0mm nozzle, 0.3MPa air pressure), spray at a distance of 25~35cm, maintaining a 90° vertical spray angle as much as possible, with a reciprocating speed of 0.5m / s. After cleaning the mold, apply two coats initially, with a 3~5min interval between coats. Add the intermediate layer release agent to a 2.0mm nozzle spray gun, adjusting the spray pattern (spray fan) so that the fan width is 30~40cm when the spray gun is 30~40cm away from the mold surface, maintaining a 90° vertical spray angle as much as possible. The moving speed is approximately 0.5 m / s, and the moving path is S-shaped. Each layer of release agent should overlap the previous layer by 1 / 3 to prevent missed areas. One coat is sufficient on top of the base layer of release agent. After spraying, keep warm for 2-3 minutes before production. There are 172 coats that do not require thorough cleaning and recoating.

[0041] Comparative Example 1: Release agent preparation process: Mix 300g hydroxyl silicone oil, 100g methyltriethylsilane, 160g vinyl silicone oil, and 60g emulsifier, heat to 60~70℃, stir for 40 minutes (800~1000rpm) until completely homogenized, emulsified and dispersed, slowly add 500g of deionized water in 4 portions, 5 minutes apart each time, to form a crude emulsion, and process it three times using a high-pressure homogenizer (80~120MPa) to control the emulsion particle size to 80-150nm; add 20g nano SiO2, ultrasonically disperse for 30min (500W power, 20kHz frequency), cool to below 40℃, add organotin catalyst, and stir at low speed for 15 minutes (200rpm); adjust the pH of the emulsion to 5.5~6.5 with acetic acid; filter through a 5μm filter, fill into a light-proof container, and store at 5~30℃.

[0042] Spraying Process: Clean the mold surface (verify the mold is a two-cavity product, approximately 1680×1250×25mm) thoroughly with a cleaning agent (acetone, silver crystal cleaner, etc.) to ensure no residue remains; preheat the mold to 80~110℃; add the release agent to a 2.0mm nozzle spray gun, adjust the spray pattern (spray fan) so that the fan is 30~40cm wide when the spray gun is 30~40cm away from the mold surface, and maintain a 90° perpendicular spray angle as much as possible. The moving speed is approximately 0.5m / s, and the moving path is S-shaped. Each coat of release agent should overlap the previous coat by 1 / 3 to prevent missed areas. After cleaning the mold, apply the first three coats, with a 2~3min interval between each coat. After the third coat, maintain the temperature for 2~3min before production. There are 73 coats that do not require thorough cleaning and recoating.

Claims

1. An HP-RTM external release agent, comprising a bottom reinforcing phase and a middle and surface functional phase; the thickness of the bottom reinforcing phase is 0.2~5μm; the total thickness of the middle and surface functional phase is 1-20μm; the bottom reinforcing phase comprises 5~15% vinyl silicone resin, 2~6% hydrogen-containing silicone resin, 70~88% hydrocarbon solvent, 0.2~1.5% nano silica, 0.3~1.5% fluorinated leveling agent, and 5~60ppm platinum-based catalyst; the middle and surface functional phase comprises 10~40% hydroxyl silicone oil; 3~15% silane crosslinking agent; 8~20% modified silicone oil; 3~10% nonionic emulsifier; 20~60% deionized water; 0.5~5% nano silica; and 0.01~0.5% organotin catalyst.

2. The external release agent according to claim 1, characterized in that... The base release agent includes 8-12% vinyl silicone resin, 3-5% hydrogen-containing silicone resin, 75-85% hydrocarbon solvent, 0.5-1% nano silica, 0.5-1% fluorinated leveling agent, and 10-50 ppm platinum-based catalyst.

3. The external release agent according to claim 1, characterized in that... The intermediate surface release agent includes 20-30% hydroxyl silicone oil, 5-10% silane crosslinking agent, 10-18% modified silicone oil, 4-8% nonionic emulsifier, 30-50% deionized water, 1-3% nano silica, and 0.1-0.3% organotin catalyst.

4. The external release agent according to claim 1, characterized in that... The vinyl silicone resin is one or more of terminal vinyl silicone resin, side-chain vinyl silicone resin, and MQ vinyl silicone resin; the hydrogen-containing silicone resin is one or more of branched hydrogen-containing silicone resin and MQ hydrogen-containing silicone resin; the alkane solvent is one or more of alkanes, alkenes, cycloalkanes, and aromatics with a carbon chain of 3-12, preferably one or more of isohexane, cyclohexane, isopropane, and isobutane; the silane crosslinking agent is one or more of methyltriethylsilane and tetramethylsilane; the modified silicone oil is one or more of alkyl silicone oil, vinyl silicone oil, and amino silicone oil; the hydroxyl silicone oil is one of terminal hydroxyl polydimethylsiloxane and side-chain hydroxyl silicone oil; the average particle size of the nano-silica is 10-100 nm; the platinum catalyst is one or more of platinum / alumina, platinum / silica, platinum chloric acid, and platinum black, and the amount of platinum catalyst used is calculated based on the platinum content; the organotin is one or more of dibutyltin diacetate and stannous octoate.

5. A method for preparing the external release agent according to any one of claims 1-4, comprising the following steps: (1) Preparation of bottom layer release agent: add isoparaffin solvent to reaction vessel, control temperature at 25±5℃, stir and mix evenly, slowly add vinyl resin, continue stirring until completely dissolved, heat hydrogen-based silicone resin and fluorinated leveling agent, raise temperature to 40℃-50℃, continue high-speed stirring and add nano silica and platinum catalyst to cool to room temperature, filter to obtain bottom layer release agent. (2) Preparation process of intermediate surface release agent: Silicone oil phase premixing, hydroxyl silicone oil, modified silicone oil, silane crosslinking agent and emulsifier are mixed and heated to 60~70℃; deionized water is added and dispersed evenly, and the emulsion particle size is controlled to be 80-150nm; nano silica is added, the temperature is lowered to below 40℃, organotin catalyst is added, and the pH value of the emulsion is adjusted to 5.5~6.5; after filtration, the intermediate surface release agent is obtained.

6. The method according to claim 5, characterized in that... The processes described in steps (1) and (2) must be carried out under stirring conditions, and the stirring speed is 100-500 rpm; the high-speed stirring speed described in step (1) is 1000-3000 rpm, and preferably, the stirring process is carried out under ultrasonic conditions.

7. The method according to claim 5, characterized in that... The deionized water in step (2) is added multiple times, preferably in 4-8 times, with an interval of 3-10 minutes between each addition; the addition of deionized water is carried out in a high-pressure homogenizer with a working pressure of 80-120 MPa, and the process is repeated 3-5 times.

8. A method of using the HP-RTM external release agent as described in any one of claims 1-4, comprising the following steps: (a) Clean the mold surface and heat the mold to 80~110℃; (b) Add the base release agent to the low-pressure high-flow (HVLP) spray gun and spray two coats for the first time, with a spray interval of 3-5 minutes; (c) Add the intermediate surface release agent to the spray gun and spray it once on the basis of the bottom release agent. After spraying, keep it warm for 2-3 minutes before production.

9. The method according to claim 8, characterized in that... During the use of HP-RTM external release agent, depending on the demolding situation, a bottom layer of release agent should be sprayed every 40-50 molds, and a middle surface layer of release agent should be sprayed every 10-15 molds.

10. The method according to claim 8, characterized in that... The cleaning process described in step (a) uses organic solvents and / or cleaning agents, including ketones, ethers, and alcohols, preferably one of acetone and ethanol; the nozzle diameter of the spray gun in step (b) is 1.2-2 mm, the pressure is 0.2-0.5 MPa, and the distance is 25-35 cm; the moving path of the spray gun in step (c) is S-shaped, and each path overlaps with the previous spraying path by 1 / 3-1 / 2.