A release agent and its preparation method

Abstract

This invention belongs to the field of mold release agent technology, and provides a mold release agent and its preparation method. The mold release agent of this invention comprises the following components by weight percentage: 15-25% hyperbranched polyamide-modified polysiloxane, 3-8% hydrophobic cellulose nanofibers, 10-15% microcapsules, 1-3% emulsifier, and water to 100%. The preparation method of the hyperbranched polyamide-modified polysiloxane includes the following steps: condensing hyperbranched polyamide and 3-hydroxyphenylphosphopropionic acid to obtain a first intermediate; substituting the first intermediate with alkyllithium to obtain a second intermediate; and silanizing the second intermediate, polysiloxane, and platinum catalyst to obtain the hyperbranched polyamide-modified polysiloxane. The mold release agent of this invention can mitigate silicon migration pollution; it is also an all-aqueous system with low VOC emissions, making it more environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of mold release agent technology, and in particular to a mold release agent and its preparation method. Background Technology

[0002] High-temperature molding processes (such as automotive die casting, precision rubber manufacturing, and composite material manufacturing) all utilize mold release agents. Commonly used mold release agents are typically silicone-based; however, silicone mold release agents are prone to migration contamination, meaning the silicone oil in the agent can migrate into the product, with migration amounts exceeding 0.5 μg / cm³. 2 This can affect secondary processing (such as bonding failure of aerospace composite materials). In addition, silicone release agents also pose environmental risks, with VOC emissions as high as 200~500g / L. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a mold release agent and its preparation method. The mold release agent of this invention can slow down silicone migration pollution; at the same time, the mold release agent provided by this invention is an all-water system with low VOC emissions, making it more environmentally friendly.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a release agent comprising the following components by weight percentage: Hyperbranched polyamide-modified polysiloxane 15-25%, hydrophobic cellulose nanofibers 3-8%, microcapsules 10-15%, emulsifier 1-3%, water to 100%; The preparation method of the hyperbranched polyamide-modified polysiloxane includes the following steps: The first intermediate was obtained by condensing hyperbranched polyamide and 3-hydroxyphenylphosphopropionic acid. The first intermediate and alkyllithium were subjected to a substitution reaction to obtain the second intermediate; The second intermediate, polysiloxane, and platinum catalyst were subjected to a silanization reaction to obtain the hyperbranched polyamide-modified polysiloxane. The water contact angle of the hydrophobic cellulose nanofibers is greater than or equal to 115°; The microcapsule comprises a wall material and a core material. The wall material is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer, and the core material is a mixture of dimethyl silicone oil and isopropyl palmitate.

[0005] Preferably, the hyperbranched polyamide has a molecular weight of 2000-10000, a branching degree of 0.5-0.8, and terminal functional groups of amino and / or hydroxyl groups; The mass ratio of the hyperbranched polyamide to 3-hydroxyphenylphosphonopropionic acid is 10~20:10~12, and the condensation reaction is carried out at a temperature of 60~70℃ for 110~130 min. The alkyllithium includes one or more of n-butyllithium, tert-butyllithium, and n-hexyllithium; the mass ratio of the hyperbranched polyamide to the alkyllithium is 10~20:0.5~1.5; the temperature of the substitution reaction is 20~25℃ and the time is 30~60min. The polysiloxane is a hydrogen-terminated polysiloxane, and the platinum catalyst includes one or more of chloroplatinic acid catalyst, Karstedt catalyst, and Ashby catalyst; the mass ratio of the hyperbranched polyamide to the polysiloxane is 10~20:30~50, the mass ratio of the polysiloxane to the platinum catalyst is 1:0.00001~0.0002, and the silanization reaction is carried out at a temperature of 100~120℃ for 3~8 hours.

[0006] Preferably, the method for preparing the hydrophobic cellulose nanofibers includes the following steps: After dispersing cellulose nanofibers, a modifier is added to carry out a modification reaction to obtain the hydrophobic cellulose nanofibers. The modifier is an alkyltriethoxysilane; The mass of the modifier is 0.1-0.5% of the mass of the cellulose nanofibers; The modification reaction is carried out at a temperature of 50-70°C for 3-5 hours.

[0007] Preferably, the dispersant used for dispersion is a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water in the mixed solvent is 1:1; The alkyltriethoxysilane includes one or more of decyltriethoxysilane, octyltriethoxysilane, and hexyltriethoxysilane.

[0008] Preferably, the microcapsules have a particle size of 5-20 μm; the core material content in the microcapsules is 60-70% by mass; and the mass ratio of dimethyl silicone oil to isopropyl palmitate in the mixture of dimethyl silicone oil and isopropyl palmitate is 1.5-2.5:1.

[0009] Preferably, the method for preparing the microcapsules includes the following steps: Dimethyl silicone oil and isopropyl palmitate are mixed to obtain the core material; An aqueous solution of polyphenylene sulfide prepolymer and an aqueous solution of maleic anhydride-grafted ethylene-vinyl acetate copolymer prepolymer are mixed to obtain a prepolymer mixed solution. The core material and the prepolymer mixture solution are emulsified under high pressure microfluidic jet and then crosslinked and cured to obtain the microcapsules; The high-pressure microjet emulsification is carried out at a pressure of 90~110MPa, a temperature of 10~40℃, and a time of 5~20min. The cross-linking curing temperature is 280~300℃, and the time is 0.5~2h.

[0010] Preferably, the release agent also includes a lubricant, wherein the weight percentage of the lubricant in the release agent is 1-2%, and the lubricant includes boron nitride and / or graphene.

[0011] Preferably, the emulsifier has an HLB value of 10-15, and the emulsifier includes one or more of sucrose esters, polysorbates, and alkylphenol polyoxyethylene ethers.

[0012] The present invention also provides a method for preparing the release agent described in the above technical solution, comprising the following steps: After heating hyperbranched polyamide-modified polysiloxane, hydrophobic cellulose nanofibers, microcapsules, emulsifiers, and water are added sequentially, and homogenized emulsification is carried out to obtain the release agent.

[0013] Preferably, the heating temperature is 70~90℃ and the heating time is 10~30min; The hydrophobic cellulose nanofibers are added at a temperature of 70~90℃. After the hydrophobic cellulose nanofibers are added, they are further dispersed at a speed of 2000~3000 rpm for a time of 20~30 min. The microcapsules are added at a temperature of 40~50℃; The homogenization emulsification is carried out at a temperature of 30-50℃, a pressure of 30-50MPa, and a time of 10-20min.

[0014] This invention provides a release agent.

[0015] The release agent of this invention uses hyperbranched polyamide-modified polysiloxane as the film-forming matrix. Due to the three-dimensional network structure of the hyperbranched polyamide-modified polysiloxane, it can encapsulate the core material (dimethyl silicone oil and isopropyl palmitate) within the microcapsules, mitigating the migration risk of silicone (dimethyl silicone oil) and allowing the release agent to maintain low release force for a longer period, thus significantly increasing the number of release cycles. The wall material of the microcapsules is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer, which can regulate the thermal response of the microcapsules between 100 and 300°C, allowing the core material to be slowly released between 100 and 300°C, maintaining the low release force of the release agent at 100-300°C. The low surface energy of the hydrophobic cellulose nanofibers can reduce the release force of the release agent, thereby increasing the number of release cycles; simultaneously, the hydrophobic cellulose nanofibers also serve as a nano-reinforcing skeleton, significantly improving the temperature resistance and mechanical properties of the coating formed by the release agent. Meanwhile, the release agent of this invention is an all-water system with low VOC emissions, making it more environmentally friendly.

[0016] Furthermore, the use of lubricant can further reduce the demolding force and improve the demolding effect. Attached Figure Description

[0017] Figure 1 The Fourier transform infrared spectrum of HBPA-PSO obtained in Example 1; Figure 2 The differential scanning calorimetry results are for the microcapsules obtained in Example 1. Detailed Implementation

[0018] This invention provides a release agent comprising the following components by weight percentage: Hyperbranched polyamide-modified polysiloxane 15-25%, hydrophobic cellulose nanofibers 3-8%, microcapsules 10-15%, emulsifier 1-3%, water to 100%; The preparation method of the hyperbranched polyamide-modified polysiloxane includes the following steps: The first intermediate was obtained by condensing hyperbranched polyamide and 3-hydroxyphenylphosphopropionic acid. The first intermediate and alkyllithium were subjected to a substitution reaction to obtain the second intermediate; The second intermediate, polysiloxane, and platinum catalyst were subjected to a silanization reaction to obtain the hyperbranched polyamide-modified polysiloxane. The water contact angle of the hydrophobic cellulose nanofibers is greater than or equal to 115°; The microcapsule comprises a wall material and a core material. The wall material is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer, and the core material is a mixture of dimethyl silicone oil and isopropyl palmitate.

[0019] The release agent provided by the present invention comprises 15-25% by weight of hyperbranched polyamide modified polysiloxane (HBPA-PSO), preferably 15%, 18%, 20%, 22% or 25%.

[0020] In this invention, the preparation method of the hyperbranched polyamide-modified polysiloxane includes the following steps: The first intermediate was obtained by condensing hyperbranched polyamide and 3-hydroxyphenylphosphopropionic acid. The first intermediate and alkyllithium were subjected to a substitution reaction to obtain the second intermediate; The second intermediate, polysiloxane, and platinum catalyst were subjected to a silanization reaction to obtain the hyperbranched polyamide-modified polysiloxane.

[0021] This invention involves a condensation reaction of hyperbranched polyamide (HBPA) and 3-hydroxyphenylphosphopropionic acid to obtain a first intermediate. In this invention, the molecular weight of the hyperbranched polyamide is preferably 2000-10000, specifically 2000, 2200, 2500, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000; the degree of branching is preferably 0.5-0.8, specifically 0.5, 0.6, 0.7, or 0.8; and the terminal functional groups are preferably amino and / or hydroxyl. In this invention, the mass ratio of the hyperbranched polyamide to 3-hydroxyphenylphosphopropionic acid is preferably 10-20:10-12, specifically 1:1. In this invention, the solvent used in the condensation reaction preferably includes one or more of n-octane, isooctane, and isononane, and the preferred volume ratio of the hyperbranched polyamide to the solvent is 1 g:8 mL. In this invention, the temperature of the condensation reaction is preferably 60-70°C, more preferably 65°C; the time is preferably 110-130 min, specifically 110 min, 115 min, 120 min, 125 min, or 130 min. After the condensation reaction, the first intermediate is preferably obtained directly without any processing.

[0022] After obtaining the first intermediate, the present invention performs a substitution reaction between the first intermediate and alkyllithium to obtain a second intermediate. In the present invention, the alkyllithium preferably includes one or more of n-butyllithium, tert-butyllithium, and n-hexyllithium. In the present invention, the mass ratio of the hyperbranched polyamide to the alkyllithium is preferably 10-20:0.5-1.5, more preferably 10:0.5-1.5, and specifically preferably 10:0.5, 10:0.7, 10:1, or 10:1.5. In the present invention, the temperature of the substitution reaction is preferably 20-25°C, and the time is preferably 30-60 min, specifically preferably 30 min, 40 min, 50 min, or 60 min. After the substitution reaction is completed, the present invention preferably obtains the second intermediate directly without any post-processing.

[0023] After obtaining the second intermediate, the present invention performs a silanization reaction on the second intermediate, the polysiloxane, and the platinum catalyst to obtain the hyperbranched polyamide-modified polysiloxane. In the present invention, the polysiloxane is preferably a hydrogen-terminated polysiloxane. In the present invention, the platinum catalyst preferably includes one or more of a chloroplatinic acid catalyst, a Karstedt catalyst, and an Ashby catalyst. In the present invention, the mass ratio of the hyperbranched polyamide to the polysiloxane is preferably 10-20:30-50, more preferably 10:30-50, and specifically preferably 10:30, 10:40, or 10:50. In the present invention, the mass ratio of the polysiloxane to the platinum catalyst is preferably 1:0.00001-0.0002, and specifically preferably 1:0.00001, 1:0.00005, 1:0.0001, 1:0.00015, or 1:0.0002. In this invention, the temperature of the silanization reaction is preferably 100~120℃, specifically 100℃, 105℃, 110℃, 115℃ or 120℃; the time is preferably 3~8h, specifically 3h, 4h, 5h, 6h, 7h or 8h. After the silanization reaction is completed, this invention preferably further includes: adding the obtained silanization reaction solution to a precipitant for precipitation, then performing solid-liquid separation to obtain a precipitate; washing and drying the precipitate sequentially to obtain the hyperbranched polyamide-modified polysiloxane. In this invention, the precipitant preferably includes one or more of n-hexane, petroleum ether, methanol and ethanol; the precipitation is preferably carried out under stirring conditions; the precipitation temperature is preferably room temperature, i.e., neither additional heating nor additional cooling is required; this invention does not specifically limit the precipitation time, until no more solid is precipitated; the solid-liquid separation method is preferably filtration or centrifugation; the drying temperature is preferably 40~60℃, more preferably 50℃; the time is preferably 1~2h; the drying is preferably carried out in a vacuum drying oven. In this invention, the hyperbranched polyamide-modified polysiloxane has a three-dimensional network structure. Using it as a film-forming matrix, it can encapsulate the core material (dimethyl silicone oil and isopropyl palmitate) in the microcapsules, reduce the migration risk of silicone (dimethyl silicone oil), and enable the release agent to have low release force for a longer period of time, thereby significantly increasing the number of times the release agent can be released.

[0024] The release agent provided by this invention comprises 3-8% hydrophobic cellulose nanofibers by weight percentage, preferably 3%, 4%, 5%, 6%, 7%, or 8%. In this invention, the water contact angle of the hydrophobic cellulose nanofibers is greater than or equal to 115°, more preferably 115°~160°, and specifically preferably 152°. In this invention, the particle size of the hydrophobic cellulose nanofibers is preferably 500-1000 nm.

[0025] In this invention, the preferred method for preparing the hydrophobic cellulose nanofibers includes the following steps: dispersing the cellulose nanofibers, adding a modifier, and performing a modification reaction to obtain the hydrophobic cellulose nanofibers. In this invention, the particle size of the cellulose nanofibers is preferably 400-600 nm. In this invention, the dispersant used for dispersion is preferably a mixed solvent of ethanol and water, and the volume ratio of ethanol to water in the mixed solvent is preferably 1:1. In this invention, the mass ratio of the cellulose nanofibers to the dispersant is preferably 125 g: 1000 mL. In this invention, the modifier is preferably an alkyltriethoxysilane, and the alkyltriethoxysilane preferably includes one or more of decyltriethoxysilane, octyltriethoxysilane, and hexyltriethoxysilane. In this invention, the mass of the modifier is preferably 0.1-0.5% of the mass of the cellulose nanofibers, specifically preferably 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%. In this invention, the preferred temperature for the modification reaction is 50-70°C, more preferably 60°C; the preferred pH value is 4.5-5.5, more preferably 5.0; the preferred time is 3-5 hours, more preferably 4 hours; and the preferred reagent for adjusting the pH value of the modification reaction is acetic acid. After the modification reaction, this invention preferably further includes: centrifuging the modified reaction system, drying the obtained solid, and obtaining the hydrophobic cellulose nanofibers. In this invention, the hydrophobic cellulose nanofibers have low surface energy, which can reduce the release force of the release agent and increase the number of release cycles; at the same time, the hydrophobic cellulose nanofibers, as a nano-reinforcing skeleton, can significantly improve the temperature resistance and mechanical properties of the coating formed by the release agent.

[0026] The release agent provided by this invention comprises 10-15% microcapsules by weight percentage, specifically preferably 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, or 15%. In this invention, the particle size of the microcapsules is preferably 5-20 μm, specifically preferably 1 μm, 10 μm, 15 μm, or 20 μm. In this invention, the mass content of the core material in the microcapsules is preferably 60-70%, more preferably 65%. In this invention, the microcapsules comprise a wall material and a core material. In this invention, the wall material is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer; the mass ratio of polyphenylene sulfide to maleic anhydride-grafted ethylene-vinyl acetate copolymer in the composite material is preferably 1:0.3~0.5, specifically preferably 1:0.3, 1:0.35, 1:0.4, 1:0.45 or 1:0.5. In this invention, the wall material of the microcapsule is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer, wherein the melting point of polyphenylene sulfide is 285~300℃; the melting point of maleic anhydride-grafted ethylene-vinyl acetate copolymer is 99℃. Using the composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer as the wall material can adjust the thermal responsiveness of the microcapsule between 100~300℃. For example, at 150℃, the low-melting-point EVA melts to form a release channel, while the PPS phase remains a solid skeleton to maintain the shape of the microcapsule; the 150℃-triggered release of the core material is achieved through controlled release by melting the EVA phase. In this invention, the core material is a mixture of dimethyl silicone oil and isopropyl palmitate. In this invention, the mass ratio of dimethyl silicone oil to isopropyl palmitate in the mixture is preferably 1.5~2.5:1, more preferably 2:1.

[0027] In this invention, the preparation method of the microcapsules includes the following steps: mixing dimethyl silicone oil and isopropyl palmitate to obtain a core material; mixing an aqueous solution of a prepolymer of polyphenylene sulfide and an aqueous solution of a prepolymer of maleic anhydride-grafted ethylene-vinyl acetate copolymer to obtain a prepolymer mixed solution; subjecting the core material and the prepolymer mixed solution to high-pressure microfluidic emulsification, followed by crosslinking and curing, to obtain the microcapsules. This invention does not specifically limit the method of mixing the dimethyl silicone oil and isopropyl palmitate.

[0028] This invention involves mixing dimethyl silicone oil and isopropyl palmitate to obtain a core material. In this invention, the viscosity of the dimethyl silicone oil is preferably 2000 cP, and the dimethyl silicone oil is preferably industrial grade. This invention does not specify the particular method of mixing the dimethyl silicone oil and isopropyl palmitate.

[0029] This invention involves mixing an aqueous solution of a prepolymer of polyphenylene sulfide (PPS) and an aqueous solution of a prepolymer of maleic anhydride-grafted ethylene-vinyl acetate copolymer to obtain a prepolymer mixed solution. In this invention, the concentration of the PPS prepolymer aqueous solution is preferably 20-40 wt%, specifically preferably 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%. The mass ratio of the PPS prepolymer aqueous solution to the maleic anhydride-grafted ethylene-vinyl acetate copolymer prepolymer aqueous solution is preferably 1:0.3-0.5, specifically preferably 1:0.3, 1:0.35, 1:0.4, 1:0.45, or 1:0.5.

[0030] After obtaining the core material and prepolymer mixed solution, the present invention subjectes the core material and prepolymer mixed solution to high-pressure microjets for emulsification, followed by crosslinking and curing to obtain the microcapsules. In the present invention, the mass ratio of the prepolymer in the core material and prepolymer mixed solution is preferably 60-70:40-30, specifically preferably 65:35. In the present invention, the pressure of the high-pressure microjets for emulsification is preferably 90-110 MPa, more preferably 100 MPa; the temperature is preferably 10-40℃, specifically preferably 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, or 40℃; the time is preferably 5-20 min, specifically preferably 5 min, 6 min, 10 min, 15 min, or 20 min. In the present invention, the temperature of the crosslinking and curing is preferably 280-300℃, specifically preferably 280℃, 290℃, or 300℃; the time is preferably 0.5-2 h, specifically preferably 0.5 h, 1 h, 1.5 h, or 2 h. After the crosslinking and curing, the present invention preferably further includes: centrifuging and washing the obtained crosslinking and curing liquid to obtain wet capsules; and drying and filtering the wet capsules sequentially to obtain the microcapsules. In the present invention, the maleic anhydride in the maleic anhydride-grafted ethylene-vinyl acetate copolymer prepolymer can react with the amino or hydroxyl groups at the chain ends of the PPS prepolymer to form EVA-g-PPS graft copolymer in situ, acting as a "bridge" between the two phases and greatly improving compatibility. The wall material of the microcapsules is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer, which can regulate the thermal response of the microcapsules between 100 and 300°C, allowing the core material to be slowly released between 100 and 300°C, maintaining the low release force of the release agent at 100 to 300°C.

[0031] The release agent provided by this invention comprises 1-3% emulsifier by weight percentage, specifically preferably 1%, 1.5%, 2%, 2.5%, or 3%. In this invention, the HLB value of the emulsifier is preferably 10-15, more preferably 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, or 15. In this invention, the emulsifier preferably comprises one or more of sucrose esters, polysorbates, and alkylphenol polyoxyethylene ethers.

[0032] The release agent provided by this invention preferably includes a lubricant. In this invention, the weight percentage of the lubricant in the release agent is preferably 1-2%, specifically 1%, 1.5%, or 2%. In this invention, the lubricant preferably includes boron nitride and / or graphene. When the lubricant includes boron nitride and graphene, the mass ratio of boron nitride to graphene is preferably 0.5-3:1, specifically 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1. In this invention, the particle size of the lubricant is preferably 500-1000 nm. In this invention, when the lubricant comprises boron nitride and graphene, the lubricant is referred to as boron nitride and graphene composite powder. The preparation method of the boron nitride and graphene composite powder preferably includes the following steps: mixing boron nitride, graphene, and water, and ultrasonically dispersing the mixture to obtain a suspension; centrifuging the suspension, filtering the supernatant, and drying the resulting filter residue to obtain a self-supporting composite film; and grinding the self-supporting composite film to obtain the boron nitride and graphene composite powder. In this invention, the ultrasonic dispersion power is preferably 300-500W, more preferably 400W; the time is preferably 4-8h, more preferably 6h; the ultrasonic dispersion is preferably performed in a probe-type ultrasonic cell disruptor. In this invention, the centrifugation speed is preferably 3000-5000rpm, more preferably 4000rpm. In this invention, the filtration is preferably vacuum filtration. In this invention, the drying temperature is preferably 60-80℃, more preferably 70℃. In this invention, boron nitride and / or graphene are used as lubricants, which is more environmentally friendly than the use of perfluoroalkyl substances (PFAS) as lubricants in the prior art.

[0033] The release agent provided by this invention comprises water by weight percentage, preferably 49-71%, specifically 50%, 55%, 56.5%, 59.5%, 60%, 63.5%, 65%, or 70%. In this invention, the water is preferably deionized water. The release agent of this invention uses water as a solvent, making it more environmentally friendly and safer, and also lower in cost.

[0034] In this invention, the particle size D of the release agent 50 The preferred wavelength is 500~1000nm.

[0035] The present invention also provides a method for preparing the release agent described in the above technical solution, comprising the following steps: After heating hyperbranched polyamide-modified polysiloxane, hydrophobic cellulose nanofibers, microcapsules, emulsifiers, and water are added sequentially, and homogenized emulsification is carried out to obtain the release agent.

[0036] In this invention, the heating temperature is preferably 70~90℃, specifically 70℃, 75℃, 80℃, 85℃ or 90℃; the heating time is preferably 10~30min, specifically 10min, 15min, 20min, 25min or 30min.

[0037] In this invention, the addition temperature of the hydrophobic cellulose nanofibers is preferably 70~90℃, specifically preferably 70℃, 75℃, 80℃, 85℃ or 90℃; after the addition of the hydrophobic cellulose nanofibers, it is preferable to further disperse them, the dispersion speed is preferably 2000~3000 rpm, more preferably 2500 rpm; the dispersion time is preferably 20~30 min, more preferably 25 min.

[0038] In this invention, the addition temperature of the microcapsules is preferably 40~50℃, and more preferably 45℃.

[0039] In this invention, the temperature of homogenization emulsification is preferably 30~50℃, more preferably 40℃; the pressure is preferably 30~50MPa, more preferably 40MPa; and the time is preferably 10~20min, more preferably 15min.

[0040] In this invention, the release agent is preferably diluted with water before use, and the volume ratio of the release agent to water is preferably 1:9.

[0041] The following detailed description of the release agent and its preparation method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1 High-temperature release agent for automotive integrated die casting 1. The formula design is shown in Table 1.

[0043] Table 1. Formulation (by weight percentage) of the release agent in Example 1.

[0044] 2. Preparation method Preparation of HBPA-PSO: 100g of hyperbranched polyamide (HBPA, molecular weight 2200, degree of branching 0.8, terminal functional group amino, purchased from Hubei Xinyuhong Biomedical Technology Co., Ltd.) and 100g of... 3-Hydroxyphenylphosphopropionic acid was mixed in 800 mL of n-octane and condensed at 60 °C for 2 h to obtain the first intermediate. 7 g of n-butyllithium was added to the first intermediate, and a substitution reaction was carried out at 20 °C for 40 min to obtain the second intermediate. 300 g of hydrogen-terminated polysiloxane and a platinum catalyst (specifically, a chloroplatinic acid catalyst, with a mass of 0.00005 times the mass of the hydrogen-terminated polysiloxane) were added to the second intermediate, and a silanization reaction was carried out at 100 °C for 4 h. After the silanization reaction was completed, the resulting silanization reaction solution was slowly added to a large amount of petroleum ether under stirring. Once no more solids precipitated, a precipitate was obtained through solid-liquid separation. The precipitate was washed with water and dried in a vacuum drying oven at 50 °C for 1 h to obtain HBPA-PSO with a viscosity of 8500 cP.

[0045] The obtained HBPA-PSO was subjected to Fourier transform infrared spectroscopy (FTIR) to confirm the successful synthesis of HBPA-PSO. The results are as follows: Figure 1 As shown, from Figure 1 It can be observed that: Si-O-Si (approximately 1000-1100 cm⁻¹) -1 C=O (approximately 1650 cm) -1 Characteristic absorption peaks such as Si-H (2100-2250 cm⁻¹) are also present. -1 The disappearance of the characteristic peaks indicates that HBPA-PSO was successfully synthesized.

[0046] Preparation of hydrophobic cellulose nanofibers: 125g of cellulose nanofibers (CNF, particle size 400-600nm) were dispersed in 1000mL of ethanol / water (1:1) mixed solvent. Acetic acid was added to adjust the pH of the dispersion to 5.0. Then, 0.1wt% of decyltriethoxysilane was added, and the mixture was reacted at 60℃ for 4h. After centrifugation and drying, hydrophobic CNF (particle size 500-1000nm) was obtained. The water contact angle of the obtained hydrophobic CNF was measured, and the results showed that the water contact angle of the obtained hydrophobic CNF was 152°, exhibiting excellent hydrophobicity.

[0047] Microencapsulation: 160g of dimethyl silicone oil (viscosity 2000cP, industrial grade) and 80g of isopropyl palmitate were mixed at a mass ratio of 2:1 as the core material; 300g of polyphenylene sulfide (PPS) prepolymer aqueous solution (concentration 30wt%) and 120g of maleic anhydride-grafted ethylene-vinyl acetate copolymer (EVA) prepolymer aqueous solution (concentration 30wt%) were mixed to obtain a prepolymer mixed solution. In the prepolymer mixed solution, the mass ratio of PPS prepolymer to maleic anhydride-grafted ethylene-vinyl acetate copolymer (EVA) prepolymer was 1:0.4.

[0048] A mixture of core material and prepolymer was subjected to high-pressure microjets for emulsification. The mass ratio of prepolymer to core material in the prepolymer mixture was 35:65. The high-pressure microjets were emulsified at a pressure of 100 MPa, a temperature of 30 °C, and a time of 300 s. After emulsification, the mixture was cross-linked and cured at 290 °C for 0.5 h. Following this, the mixture was centrifuged, washed, dried, collected, and filtered through a sieve to obtain microcapsules with a particle size of 10 μm. The core material content in the microcapsules was 65%. The phase transition temperature (melting point) of the microcapsules was determined using differential scanning calorimetry (DSC). The results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the microcapsules begin to partially melt at around 150℃ and completely melt at around 290℃.

[0049] The preparation method of BN / graphene composite powder is as follows: BN powder and graphene are weighed at a mass ratio of 1:1 and added together to water. The mixture is then sonicated at 400W for 6 hours using a probe-type ultrasonic cell disruptor. The resulting suspension is centrifuged at 4000rpm, and the supernatant is collected to remove any unpeeled thick sheets. The supernatant is then vacuum filtered and vacuum dried at 70℃ to obtain a self-supporting composite film. Finally, the film is ground into powder with a particle size of 500~1000nm.

[0050] Preparation of release agent: HBPA-PSO was heated to 80℃ and held for 20 min. Hydrophobic CNF was added, and the mixture was dispersed at 3000 rpm for 30 min. After cooling to 50℃, microcapsules, BN / graphene composite powder, and water were added. Finally, the mixture was homogenized and emulsified at 50℃ and 50 MPa for 10 min to obtain a release agent stock solution with a viscosity of 350 cP. The particle size D of the release agent stock solution was... 50 The wavelength is 500~1000nm; finally, it is diluted with water at a ratio of 1:9 as a release agent.

[0051] 3. Performance Testing Demolding force test: According to the standard procedure for testing demolding force in the laboratory and the customer's on-site usage, a tensile testing machine is used to separate the product from the mold, and the maximum force when the product is separated from the mold is recorded as the demolding force.

[0052] Demolding count test: Record the number of consecutive successful demoldings that can be achieved after a single application of the release agent.

[0053] Determination of migration residue: The silicon content transferred to the surface of the product should be detected using a highly sensitive spectroscopic method (such as XPS), with a target value of <0.1 μg / cm³. 2 .

[0054] Adhesion test: Spray a layer of primer on the surface of the product and conduct an adhesion test according to the cross-cut test method of GB / T 9286, and record the peeling level.

[0055] Test of mold cleaning cycle: Observe whether there are phenomena such as sticking, whitening, or scaling on the mold surface, and record the number of times the mold is demolded when such phenomena are observed. This is the mold cleaning cycle.

[0056] The results are shown in Table 2.

[0057] Table 2 Test results of the release agent obtained in Example 1

[0058] Example 2 Medical silicone rubber release agent 1. The formula design is shown in Table 3.

[0059] Table 3. Formulation (by weight percentage) of the release agent in Example 2.

[0060] 2. Preparation process The preparation of HBPA-PSO is the same as in Example 1.

[0061] The preparation of hydrophobic CNF is the same as in Example 1.

[0062] Microcapsules: Replace the dimethyl silicone oil in the core material with medical-grade dimethyl silicone oil (viscosity 1000 cP) to ensure that it passes the ISO 10993 biocompatibility test.

[0063] In the preparation of the release agent: after homogenization and emulsification, sterilization is carried out. The specific process is: sterilization by gamma rays (dose 25kGy) to avoid the introduction of chemical bactericides.

[0064] 3. Performance Testing Demolding force test: According to the standard procedure for testing demolding force in the laboratory and the customer's on-site usage, a tensile testing machine is used to separate the product from the mold, and the maximum force when the product is separated from the mold is recorded as the demolding force.

[0065] Demolding count test: Record the number of consecutive successful demoldings that can be achieved after a single application of the release agent.

[0066] Roughness test: After the product is demolded, the surface roughness (Ra) of the product is measured with a roughness tester.

[0067] Determination of migration residue: The silicon content transferred to the surface of the product should be detected using a highly sensitive spectroscopic method (such as XPS), with a target value of <0.1 μg / cm³. 2 .

[0068] Test of mold cleaning cycle: Observe whether there are phenomena such as sticking, whitening, or scaling on the mold surface, and record the number of times the mold is demolded when such phenomena are observed. This is the mold cleaning cycle.

[0069] The results are shown in Table 4.

[0070] Table 4 Test results of the release agent obtained in Example 2

[0071] Example 3 Environmentally friendly composite material molding release agent 1. The formula design is shown in Table 5.

[0072] Table 5. Formulation (by weight percentage) of the release agent in Example 3.

[0073] 2. Preparation process The preparation of HBPA-PSO is the same as in Example 1.

[0074] The preparation of hydrophobic CNF is the same as in Example 1.

[0075] The preparation of the microcapsules is the same as in Example 1.

[0076] In the preparation of the release agent: after homogenization and emulsification, it is diluted with water at a ratio of 1:9 to serve as the release agent.

[0077] 3. Performance Testing Demolding force test: According to the standard procedure for testing demolding force in the laboratory and the customer's on-site usage, a tensile testing machine is used to separate the product from the mold, and the maximum force when the product is separated from the mold is recorded as the demolding force.

[0078] Demolding count test: Record the number of consecutive successful demoldings that can be achieved after a single application of the release agent.

[0079] Roughness test: After the product is demolded, the surface roughness (Ra) of the product is measured with a roughness tester.

[0080] Determination of migration residue: The silicon content transferred to the surface of the product should be detected using a highly sensitive spectroscopic method (such as XPS), with a target value of <0.1 μg / cm³. 2 .

[0081] Adhesion test: Spray a layer of primer on the surface of the product and conduct an adhesion test according to the cross-cut test method of GB / T 9286, and record the peeling level.

[0082] Test of mold cleaning cycle: Observe whether there are phenomena such as sticking, whitening, or scaling on the mold surface, and record the number of times the mold is demolded when such phenomena are observed. This is the mold cleaning cycle.

[0083] VOC emission testing: VOC emissions were determined using the GB / T 34682 method.

[0084] PFAS content test: The PFAS content was determined using the GB / T 31126 method.

[0085] Biodegradation rate test: The biodegradation rate was determined using the GB / T 19277 method.

[0086] The results are shown in Table 6.

[0087] Table 6 Test results of the release agent obtained in Example 3

[0088] Comparative Example 1 A semi-permanent high-temperature release agent for automotive integrated die casting, model HD-9187-1 (purchased from Shanghai Huichuang Trading Co., Ltd.), was selected from the market. The test conditions were the same as in Example 1, and the test results are shown in Table 7.

[0089] Table 7 Comparison of results obtained from Comparative Example 1 and Example 1

[0090] As shown in Table 7, compared with Example 1, the release agent in Comparative Example 1 has increased release force, reduced release times, increased residual silicon migration, decreased adhesion, and reduced mold washing cycle. Therefore, it can be concluded that the release agent in Example 1 has a better release effect and less silicon transfer.

[0091] BN / graphene composite powder can be used as a lubricant to replace PFAS, meeting EU environmental regulations.

[0092] Comparative Example 2 A commercially available medical silicone rubber release agent, model MC1625W (purchased from Kentian Chemical Co., Ltd.), was selected. The test conditions were the same as in Example 2, and the test results are shown in Table 8.

[0093] Table 8 Comparison of results obtained from Comparative Example 2 and Example 2

[0094] As shown in Table 8, compared with Example 2, the release agent in Comparative Example 2 has increased release force, reduced demolding times, increased surface roughness of the product, increased residual silicon migration, and reduced mold washing cycle. Therefore, it can be concluded that the release agent in Example 2 has a better demolding effect and less silicon transfer.

[0095] Comparative Example 3 An environmentally friendly composite material molding release agent, model W-213-1 (Shanghai Huichuang Trading Co., Ltd.), was selected from the market. The test conditions were the same as in Example 3, and the results are shown in Table 9.

[0096] Table 9 Comparison of results obtained from Comparative Example 3 and Example 3

[0097] As shown in Table 9, compared with Example 3, the release agent in Comparative Example 3 has increased release force, reduced release cycles, increased residual silicon migration, decreased adhesion, reduced mold washing cycle, increased VOC emissions, a PFAS content of 57 ppb, and a decreased biodegradability rate. Therefore, it can be concluded that the release agent in Example 3 has a better release effect, less silicon transfer, and is more environmentally friendly.

[0098] Comparative Example 4 The difference from Example 1 is that the hyperbranched polyamide-modified polysiloxane was replaced with hydrogen-terminated polysiloxane, while other conditions remained unchanged. The test results are shown in Table 10.

[0099] Table 10 Comparison of results obtained from Comparative Example 4 and Example 1

[0100] As can be seen from Table 10, compared with Example 1, the release agent in Comparative Example 4 has increased release force, the number of release cycles remains the same, the residual amount of silicon migration increases, the adhesion decreases, and the mold washing cycle remains the same. Therefore, it can be determined that the release agent in Example 1 has a better release effect and less silicon transfer.

[0101] Comparative Example 5 The difference from Example 1 is that unmodified cellulose nanofibers were used directly, while other conditions remained unchanged. The results are shown in Table 11.

[0102] Table 11 Comparison of results obtained from Comparative Example 5 and Example 1

[0103] As shown in Table 11, compared with Example 1, the release agent in Comparative Example 5 has increased release force, the number of release cycles remains the same, the residual amount of silicon migration increases, the adhesion decreases, and the mold washing cycle remains the same. Therefore, it can be determined that the release agent in Example 1 has a better release effect and less silicon transfer.

[0104] Comparative Example 6 The difference from Example 1 is that the PPS in the wall material of the microcapsules was replaced with maleic anhydride-grafted ethylene-vinyl acetate copolymer, that is, the wall material of the microcapsules was entirely maleic anhydride-grafted ethylene-vinyl acetate copolymer, and other conditions remained unchanged. The results are shown in Table 12.

[0105] Table 12 Comparison of results obtained from Comparative Example 6 and Example 1

[0106] As can be seen from Table 12, compared with Example 1, the release agent in Comparative Example 6 has a lower release force, the same number of release cycles, an increased amount of residual silicon migration, a decreased adhesion, and an unchanged mold washing cycle. Therefore, it can be determined that the release agent in Example 1 has a better release effect and less silicon transfer.

[0107] The above embodiments, through differentiated formulation adjustments and targeted performance testing, demonstrate the advantages of the release agent of the present invention in terms of high-temperature resistance, biocompatibility, and environmental compliance. The data from Examples 1-3 are significantly superior to traditional release agents and cover three high-value fields: automotive, medical, and composite materials. The release agent of the present invention can be adapted to different application scenarios by adjusting the particle size of the microcapsules or the degree of modification of the CNF surface.

[0108] The HBPA-PSO in the mold release agent provided by this invention has a three-dimensional network that can block dimethyl silicone oil from penetrating into the product; the hydrophobic CNF is biocompatible, and the cellulose nanofibers (CNF) are naturally renewable, avoiding toxicity risks.

[0109] The release agent provided by the present invention has the following advantages: (1) low silicon transferability, high adhesion, and can be demolded multiple times; (2) intelligent controlled release mechanism: microcapsules realize temperature-triggered release and extend the demolding life; (3) nano-reinforcement effect: hydrophobic CNF improves the mechanical strength and temperature resistance of the release agent coating; (4) environmental protection and compliance: BN / graphene replaces PFAS, and the water-based system reduces VOC.

[0110] 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 release agent, characterized in that, Includes the following components by weight percentage: Hyperbranched polyamide-modified polysiloxane 15-25%, hydrophobic cellulose nanofibers 3-8%, microcapsules 10-15%, emulsifier 1-3%, water to 100%; The preparation method of the hyperbranched polyamide-modified polysiloxane includes the following steps: The first intermediate was obtained by condensing hyperbranched polyamide and 3-hydroxyphenylphosphopropionic acid. The first intermediate and alkyllithium were subjected to a substitution reaction to obtain the second intermediate; The second intermediate, polysiloxane, and platinum catalyst were subjected to a silanization reaction to obtain the hyperbranched polyamide-modified polysiloxane. The water contact angle of the hydrophobic cellulose nanofibers is greater than or equal to 115°; The microcapsule comprises a wall material and a core material. The wall material is a composite material of polyphenylene sulfide and maleic anhydride-grafted ethylene-vinyl acetate copolymer, and the core material is a mixture of dimethyl silicone oil and isopropyl palmitate.

2. The release agent according to claim 1, characterized in that, The hyperbranched polyamide has a molecular weight of 2000~10000, a branching degree of 0.5~0.8, and terminal functional groups of amino and / or hydroxyl groups; The mass ratio of the hyperbranched polyamide to 3-hydroxyphenylphosphonopropionic acid is 10~20:10~12, and the condensation reaction is carried out at a temperature of 60~70℃ for 110~130 min. The alkyllithium includes one or more of n-butyllithium, tert-butyllithium, and n-hexyllithium; the mass ratio of the hyperbranched polyamide to the alkyllithium is 10~20:0.5~1.5; the temperature of the substitution reaction is 20~25℃ and the time is 30~60min. The polysiloxane is a hydrogen-terminated polysiloxane, and the platinum catalyst includes one or more of chloroplatinic acid catalyst, Karstedt catalyst, and Ashby catalyst; the mass ratio of the hyperbranched polyamide to the polysiloxane is 10~20:30~50, the mass ratio of the polysiloxane to the platinum catalyst is 1:0.00001~0.0002, and the silanization reaction is carried out at a temperature of 100~120℃ for 3~8 hours.

3. The release agent according to claim 1, characterized in that, The preparation method of the hydrophobic cellulose nanofibers includes the following steps: After dispersing cellulose nanofibers, a modifier is added to carry out a modification reaction to obtain the hydrophobic cellulose nanofibers. The modifier is an alkyltriethoxysilane; The mass of the modifier is 0.1-0.5% of the mass of the cellulose nanofibers; The modification reaction is carried out at a temperature of 50-70°C for 3-5 hours.

4. The release agent according to claim 3, characterized in that, The dispersant used for dispersion is a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water in the mixed solvent is 1:1; The alkyltriethoxysilane includes one or more of decyltriethoxysilane, octyltriethoxysilane, and hexyltriethoxysilane.

5. The release agent according to claim 1, characterized in that, The microcapsules have a particle size of 5-20 μm; the core material in the microcapsules has a mass content of 60-70%; and the mass ratio of dimethyl silicone oil to isopropyl palmitate in the mixture of dimethyl silicone oil and isopropyl palmitate is 1.5-2.5:

1.

6. The release agent according to claim 1 or 5, characterized in that, The method for preparing the microcapsules includes the following steps: Dimethyl silicone oil and isopropyl palmitate are mixed to obtain the core material; An aqueous solution of polyphenylene sulfide prepolymer and an aqueous solution of maleic anhydride-grafted ethylene-vinyl acetate copolymer prepolymer are mixed to obtain a prepolymer mixed solution. The core material and the prepolymer mixture solution are emulsified under high pressure microfluidic jet and then crosslinked and cured to obtain the microcapsules; The high-pressure microjet emulsification is carried out at a pressure of 90~110MPa, a temperature of 10~40℃, and a time of 5~20min. The cross-linking curing temperature is 280~300℃, and the time is 0.5~2h.

7. The release agent according to claim 1, characterized in that, It also includes a lubricant, wherein the weight percentage of the lubricant in the release agent is 1 to 2%, and the lubricant includes boron nitride and / or graphene.

8. The release agent according to claim 1, characterized in that, The emulsifier has an HLB value of 10-15 and includes one or more of sucrose esters, polysorbates, and alkylphenol polyoxyethylene ethers.

9. A method for preparing the release agent according to any one of claims 1 to 8, characterized in that, Includes the following steps: After heating hyperbranched polyamide-modified polysiloxane, hydrophobic cellulose nanofibers, microcapsules, emulsifiers, and water are added sequentially, and homogenized emulsification is carried out to obtain the release agent.

10. The preparation method according to claim 9, characterized in that, The heating temperature is 70~90℃, and the time is 10~30min; The hydrophobic cellulose nanofibers are added at a temperature of 70~90℃. After the hydrophobic cellulose nanofibers are added, they are further dispersed at a speed of 2000~3000 rpm for a time of 20~30 min. The microcapsules are added at a temperature of 40~50℃; The homogenization emulsification is carried out at a temperature of 30-50℃, a pressure of 30-50MPa, and a time of 10-20min.

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