Laser positioning alumite hot stamping gum and preparation method thereof

Abstract

The invention relates to the technical field of alumite hot stamping, and particularly provides laser positioning alumite hot stamping gum and a preparation method thereof. The gum is of an interpenetrating network structure formed by in-situ polymerization of the following components in parts by weight: 25-35 parts of modified polyurethane, 65-75 parts of acrylic resin, 3-5 parts of TiO2 / SiO2 core-shell nanoparticles and 0.5-1.2 parts of a reactive perfluoropolyether interfacial compatibilizer, and the energy storage modulus of the gum at 80 DEG C is 0.8 * 10 < 4 > Pa.s to 1.2 * 10 < 4 > Pa.s. When the temperature of the Si-PU / AR interpenetrating network is increased, physical crosslinking points of Si-PU are dissociated, chemical crosslinking synchronization of AR is too strong, and the effect that the viscosity fluctuation rate is lower in the temperature interval of 65-120 DEG C is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical aluminum hot stamping, and in particular to a laser positioning electrochemical aluminum hot stamping adhesive and a preparation method thereof. Background Art

[0002] Anodized aluminum hot stamping technology is a surface treatment process widely used in the fields of packaging, printing and decoration. The metal layer and holographic pattern in the anodized aluminum foil are transferred to the surface of the substrate through the principle of heat-pressing transfer, forming a decorative layer with metallic luster and three-dimensional visual effect. This technology occupies an important position in high-end packaging, label printing and anti-counterfeiting labels due to its high efficiency, beautiful appearance and anti-counterfeiting characteristics. As a key component of anodized aluminum foil, the hot stamping adhesive directly determines the integrity of the pattern transfer, adhesion strength and production efficiency during the hot stamping process.

[0003] The traditional electrochemical aluminum hot stamping process is usually carried out under high temperature conditions (generally 100℃~150℃) to ensure that the back glue is fully melted and bonded to the substrate. In recent years, with the increasing market demand for high-speed production and energy conservation and environmental protection, low-temperature and high-speed hot stamping technology has gradually become a hot spot for industry development. Low-temperature hot stamping can not only reduce energy consumption and reduce equipment heat loss, but also shorten the processing cycle and improve production efficiency. In addition, as a high-precision process, holographic positioning hot stamping requires the back glue to maintain the clarity and diffraction efficiency of the holographic pattern during the transfer process to meet the dual needs of anti-counterfeiting and decoration. However, the performance of the existing back glue system under low temperature and high-speed conditions is still significantly insufficient, which limits the widespread application of this technology.

[0004] In the prior art, common adhesive formulations are mostly based on polyvinyl butyral (PVB), ketone-aldehyde resin or acrylic resin, supplemented with organic solvents and additives. For example, patent CN 111961427 A discloses a laser holographic positioning electrochemical aluminum low-temperature high-speed hot stamping adhesive, which achieves a hot stamping temperature of 60-85°C through a combination of PVB, ketone-aldehyde resin and EVA, and an average hot stamping speed of 4500-6000 sheets / hour. However, this technology has exposed the limitations of adhesion and holographic effects in practical applications, especially in high-speed production and diversified substrates. The performance is not ideal. In addition, traditional adhesive systems mostly rely on volatile organic solvents, which not only increases VOC emissions, but also poses challenges to environmentally friendly production. Summary of the invention

[0005] In view of this, the present invention proposes a laser-positioned electrochemical aluminum hot stamping adhesive and a preparation method thereof which has better use effect in low-temperature and high-speed hot stamping scenarios.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a laser positioning electrochemical aluminum hot stamping adhesive, wherein the adhesive is formed into an interpenetrating network structure by in-situ polymerization of the following components by weight: 25-35 parts of modified polyurethane, 65-75 parts of acrylic resin, TiO 2 / SiO 2 3-5 parts of core-shell nanoparticles and 0.5-1.2 parts of reactive perfluoropolyether interfacial compatibilizer, the storage modulus of the backing adhesive at 80°C is 0.8*10 4 Pa·s-1.2*10 4 Pa·s.

[0007] In some embodiments, the modified polyurethane is silicone-modified polyurethane, which is prepared by reacting isophorone diisocyanate, polycarbonate diol and γ-aminopropyltriethoxysilane, wherein the siloxane segment accounts for 15-18% of the total mass of the polyurethane segment.

[0008] In some embodiments, TiO 2 / SiO 2 TiO in core-shell nanoparticles 2 With SiO 2 The mass ratio is 1:(1-2).

[0009] In some embodiments, TiO 2 / SiO 2 The surface of the core-shell nanoparticles is grafted with vinyl, and the vinyl grafting rate is 85%-95%. The vinyl grafting makes the interface bonding strength between the nanoparticles and the resin matrix ≥15MPa.

[0010] In some embodiments, the acrylic resin is a methyl methacrylate-butyl acrylate-hydroxyethyl acrylate copolymer, and has a glass transition temperature of -10°C to 10°C and a hydroxyl value of 50-80 mg KOH / g.

[0011] In some embodiments, the reactive perfluoropolyether has a molecular weight of 2000-5000 g / mol, a fluorine content of 50-65 wt %, and a reactive group containing an acrylate double bond.

[0012] In a second aspect, the present invention further provides a method for preparing the above-mentioned back adhesive, comprising the following steps:

[0013] Step 1: Mix the modified polyurethane prepolymer and acrylic resin monomer, add reactive perfluoropolyether, heat to 60-80°C and stir for 30-60 minutes;

[0014] Step 2: TiO 2 / SiO 2The core-shell nanoparticles are added to the mixture obtained in step 1, and ultrasonic dispersion is performed at 40kHz power 200W for 20-40min;

[0015] Step 3: Gradient temperature rise in-situ polymerization:

[0016] The first stage: 3-5℃ / min heating rate, heating to 75-85℃ and keeping warm for 30min;

[0017] The second stage: heating at a rate of 8-10℃ / min to 115-125℃ and keeping warm for 15min;

[0018] Phase 3: 365nm wavelength, 80mW / cm 2 Carry out UV curing treatment and irradiate for 10-20s.

[0019] In some embodiments, in step 2, 0.1-0.5 wt % of a silane coupling agent is added to the mixture during ultrasonic dispersion.

[0020] In some embodiments, the acrylic resin monomer comprises methyl methacrylate, butyl acrylate and hydroxyethyl acrylate in a mass ratio of (40-50):(30-40):(10-20).

[0021] Under low temperature conditions of 50℃-80℃, the traditional adhesive has poor meltability and fluidity, resulting in insufficient bonding strength with substrates (such as paper, plastic). Tests show that the peel strength of existing adhesives is generally lower than 2.5N / 15mm when hot stamping at 50℃, which is difficult to meet the high-strength adhesion requirements, especially on substrates with low surface tension (such as untreated PET or PP), the adhesion effect is further reduced. This problem is particularly prominent in high-speed hot stamping (flat hot stamping ≥6000 sheets / hour, round hot stamping ≥10000 sheets / hour), because the contact time is short and the adhesive cannot fully wet the substrate surface, resulting in adhesion failure or peeling.

[0022] Holographic positioning hot stamping requires that the adhesive backing accurately maintain the micro-nano structure of the holographic pattern during the transfer process to ensure diffraction efficiency and visual effects. However, the viscoelasticity of the adhesive backing is insufficient at low temperatures, making it difficult to completely fill the tiny concave-convex structure of the holographic layer, resulting in incomplete pattern transfer or blurred edges. In the prior art, the holographic diffraction efficiency is usually less than 70% during high-speed hot stamping, far from the 85% or more required for high-precision anti-counterfeiting. In addition, during high-speed hot stamping, the adhesive backing's ability to quickly solidify is insufficient, which can easily cause changes in the thickness of the holographic layer or surface defects, further affecting the optical performance.

[0023] The root of the above problems lies in the fact that the resin in the traditional adhesive formula has a high softening point, which makes it difficult to melt quickly at low temperatures and form strong adhesion; at the same time, the additive system is not adaptable enough to high-speed processes and fails to effectively balance adhesion and pattern transfer accuracy. These shortcomings not only limit the promotion of low-temperature and high-speed hot stamping technology, but also fail to meet the needs of modern industry for high-efficiency, energy-saving and high-quality hot stamping. Therefore, developing an adhesive that can achieve excellent adhesion and holographic effects at 50℃-80℃ has become a technical problem that needs to be solved urgently.

[0024] The present invention adopts an interpenetrating network (IPN) structure of silicone-modified polyurethane (Si-PU) and acrylic resin (AR), wherein:

[0025] The siloxane segments of Si-PU (15-18 wt%) provide low-temperature elasticity (elongation at break at -40°C > 200%);

[0026] The gradient Tg design of AR (-10~10℃) achieves dynamic equilibrium between melting and solidification (storage modulus mutation point 75-85℃);

[0027] TiO with vinyl grafted on the surface 2 / SiO 2 Core-shell particles (grafting rate ≥ 85%), when cured by UV:

[0028] TiO 2 The core (refractive index 2.5-2.7) ensures the diffraction efficiency of the holographic grating (≥83%);

[0029] SiO 2 The shell (thickness 5-8 nm) forms a chemical bond with the resin (interfacial binding energy ≥ 15 kJ / mol);

[0030] Reactive perfluoropolyether (PFPE) forms an ultra-low surface tension layer (γ<28.5mN / m) in the molten state:

[0031] Fluorocarbon segments (50-65wt%) reduce interfacial energy, making the contact angle of the backing glue on the metallized substrate less than 10°;

[0032] The acrylate end groups are copolymerized with the resin to prevent PFPE migration (the fluorine element loss rate is less than 3% after 50 hot stampings).

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention adopts Si-PU / AR interpenetrating network. When the temperature rises, the physical crosslinking points of Si-PU are dissociated, while the chemical crosslinking of AR is simultaneously enhanced, thereby achieving the effect of lower viscosity fluctuation rate in the temperature range of 65-120°C. UV triggers the vinyl grafting reaction on the surface of nanoparticles, and heat-induced resin polymerization forms a dual-curing network, so that the interface bonding strength is increased to 2.3 times that of the conventional system. The flexible chain segments of Si-PU and the rigid chain segments of AR in the IPN structure form a micro gradient, which effectively improves the interface shear stress dispersion efficiency. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0037] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0038] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0039] Example 1

[0040] Raw materials and equipment

[0041] Silicone modified polyurethane (Si-PU) prepolymer

[0042] Synthetic raw materials:

[0043] Isophorone diisocyanate (IPDI, Wanhua Chemical, purity ≥ 99.5%)

[0044] Polycarbonate diol (PCDL, Mn = 2000, hydroxyl value 56 mg KOH / g)

[0045] γ-Aminopropyltriethoxysilane (KH-550, Nanjing Shuguang, purity ≥98%)

[0046] Molar ratio: IPDI:PCDL:KH-550=2.2:1:0.3

[0047] Acrylic resin monomer

[0048] Methyl methacrylate (MMA, Dow Chemical, purity ≥99.8%)

[0049] Butyl acrylate (BA, BASF, purity ≥ 99.5%)

[0050] Hydroxyethyl acrylate (HEA, Nippon Catalyst, purity ≥99%)

[0051] Mass ratio: MMA:BA:HEA=45:35:20

[0052] Nanoparticles:

[0053] TiO 2 / SiO 2 Core-shell nanoparticles (Zhongke Natong, model ZK-NT01, TiO 2 :SiO 2 =1:1.5, surface vinyl grafting rate 90%, D50 = 35nm)

[0054] Reactive perfluoropolyether (PFPE):

[0055] Daikin Industries, Model UNIDYNE TM TG-551, molecular weight 3500, fluorine content 60%, with acrylate end groups

[0056] equipment:

[0057] Four-necked flask (500 mL, with mechanical stirring, thermometer, nitrogen inlet)

[0058] Ultrasonic disperser (BILON98-Ⅲ, 40kHz / 500W)

[0059] UV curing machine (Heraeus, Model S2000, wavelength 365nm, intensity 80mW / cm 2 )

[0060] Detailed preparation steps

[0061] 1. Preparation of Si-PU prepolymer

[0062] ① Under the protection of dry nitrogen, add IPDI (43.2 g, 0.194 mol) and PCDL (40 g, 0.02 mol) into a four-necked flask and heat to 80°C.

[0063] ② Add dibutyltin dilaurate (0.05wt%, 0.04g) dropwise with stirring at 200rpm and react for 2 hours until the NCO content reaches 7.2% (determined according to ASTM D2572).

[0064] ③ Cool down to 60°C, add KH-550 (4.8 g, 0.018 mol), and continue the reaction for 1.5 hours to obtain a light yellow viscous prepolymer (viscosity 3200 mPa·s at 25°C) with a siloxane content of 16%.

[0065] 2. Raw material mixing

[0066] ① Mix Si-PU prepolymer (30g) and acrylic monomer (MMA31.5g, BA 24.5g, HEA 14g).

[0067] ② Add PFPE (0.8 g), place in a 60°C water bath, and stir mechanically at 500 rpm for 40 minutes until homogeneous.

[0068] 3. Nanoparticle dispersion

[0069] ① TiO 2 / SiO 2 Nanoparticles (4 g) were premixed with silane coupling agent KH-570 (0.2 g).

[0070] ② Add the above mixture and use an ultrasonic disperser (40kHz, 500W) to treat for 30 minutes (on / off cycle 5s / 5s), and the slurry temperature is controlled at 50±2℃.

[0071] 4. Gradient temperature in-situ polymerization

[0072] ① The first stage: the mixture was transferred to the coating machine trough, the temperature was raised to 80°C at 4°C / min, and kept warm for 30 minutes (Si-PU crosslinking degree 65%, NCO characteristic peak disappeared as monitored by FTIR).

[0073] ② The second stage: the temperature was raised to 120°C at 9°C / min, and benzoyl peroxide (BPO, 0.25 g) was added twice:

[0074] First addition 0.15g (added at 110℃)

[0075] The second addition is 0.10g (added at 115°C)

[0076] ③ Maintain nitrogen atmosphere (oxygen content <100 ppm) and react for 15 minutes until the viscosity of the system stabilizes (Brookfield DV2T, 25°C / spindle 21, reading 58 cP).

[0077] 5. UV curing

[0078] ① Transfer the semi-cured film to the PET substrate (thickness 25μm) through a roller coater, with a coating amount of 8g / m 2 .

[0079] ② Under 0.2MPa pressure, pass through UV curing machine at a speed of 2m / min (cumulative irradiation 1200mJ / cm 2 ).

[0080] ③ Post-curing: Curing in 60℃ oven for 20 minutes.

[0081] Example 2

[0082] In this example, based on Example 1, the amount of KH-550 added during the preparation of Si-PU prepolymer was adjusted (4.5 g, 0.0168 mol), and the siloxane content of the obtained light yellow viscous prepolymer was 15%.

[0083] Example 3

[0084] In this example, based on Example 1, the amount of KH-550 added during the preparation of Si-PU prepolymer was adjusted (5.4 g, 0.0203 mol), and the siloxane content of the obtained light yellow viscous prepolymer was 18%.

[0085] Comparative Example 1

[0086] This comparative example uses unmodified polyurethane

[0087] On the basis of Example 1, Si-PU prepolymer was replaced with ordinary polyurethane (Wanhua Chemical, Model 6210, without siloxane modification), other conditions remain unchanged.

[0088] In the preparation method, the step of adding KH-550 was omitted, and commercially available PU prepolymer was directly used. Since the viscosity of ordinary PU prepolymer was relatively high (25°C / 6500mPa·s), the stirring speed was increased to 800rpm.

[0089] Comparative Example 2

[0090] This comparative example does not contain PFPE

[0091] On the basis of Example 1, PFPE was completely removed, and 5 g of butyl acrylate was additionally added to maintain the viscosity of the system, while other conditions remained unchanged.

[0092] In the preparation method, only Si-PU prepolymer, acrylic monomer and nanoparticles are added in the mixing stage, and the UV curing pressure is increased to 0.3MPa to compensate for the lack of wettability.

[0093] Comparative Example 3

[0094] This comparative example uses ungrafted nanoparticles

[0095] Based on Example 1, unmodified TiO 2 / SiO 2 Core-shell nanoparticles (same supplier, model ZK-NT00, no vinyl grafting) were added with 2 wt% titanate coupling agent NDZ-201 to improve dispersibility, while other conditions remained unchanged.

[0096] In the preparation method, the ultrasonic dispersion time was extended to 50 min (to avoid serious particle agglomeration), and the UV curing dose was increased to 1800 mJ / cm 2 .

[0097] Comparative Example 4

[0098] This comparative example adopts the traditional one-step process

[0099] On the basis of Example 1, the gradient temperature rise was cancelled, and the curing was directly carried out at 120° C. for 60 min, and no pressure was applied during the UV curing stage.

[0100] In the preparation method, the temperature is directly raised to 120° C. after the materials are mixed, the initiator is added at one time, and there is no UV treatment after curing, only hot air drying.

[0101] The performance of the adhesives prepared in the above examples and comparative examples was tested respectively, and the specific methods are as follows:

[0102] Peel strength test

[0103] Standard: ASTM D903 (180° peeling method)

[0104] Equipment: Instron 5967 universal materials testing machine (50N sensor)

[0105] step:

[0106] The adhesive was coated on a 25 μm PET substrate and hot-stamped with aluminum foil (12 μm thick).

[0107] The sample was cut into 25 mm × 150 mm, and the length of the bonding section was 100 mm.

[0108] The stripping was performed at a speed of 300 mm / min, and the force value in the stable section was recorded (excluding the data of the first 20 mm and the last 20 mm).

[0109] 2. Holographic diffraction efficiency test

[0110] Standard: ISO 13695 (laser interferometry)

[0111] Equipment: Holotest 3000 holographic analyzer

[0112] step:

[0113] A 532 nm laser source was used with an incident angle of 45° and a spot diameter of 2 mm.

[0114] Measure the incident light intensity (Iincident) and the first-order diffracted light intensity (Idiffracted).

[0115] calculate:

[0116] Diffraction efficiency = I diffracted / I incident ×100%

[0117] 3. VOC emission detection

[0118] Standard: HJ 2537-2014 (Headspace-Gas Chromatography)

[0119] Equipment: Agilent 7890B gas chromatograph (FID detector)

[0120] condition:

[0121] Chromatographic column: DB-624 (60m×0.32mm×1.8μm)

[0122] Inlet temperature: 250°C, detector temperature: 300°C

[0123] Column temperature program: 40℃(5min)→10℃ / min→240℃(10min)

[0124] step:

[0125] Take 1 g of sample and place it in a 20 mL headspace bottle and heat it at 80 °C for 30 min.

[0126] 1 mL of headspace gas was extracted and injected, and quantification was performed using the external standard method.

[0127] 5. Low temperature resistance test

[0128] Standard: GB / T 2423.1-2008 (Low Temperature Storage Test)

[0129] Equipment: Espec SH-642 high and low temperature test chamber

[0130] step:

[0131] The samples were stored at -40°C for 24 h and then returned to room temperature (23°C).

[0132] After 5 cycles, 1 cm was counted using a 20x microscope. 2 Number of internal cracks:

[0133] No cracks: 0

[0134] Micro cracks: 1-5

[0135] Crack rate = (crack area / total area) × 100%

[0136] The test results are shown in the following table:

[0137]

[0138] The low temperature hot stamping performance of Example 1 at 65°C hot stamping temperature is 31.6% lower than that of Comparative Example 1 (95°C), which is attributed to: the plasticizing effect of the Si-PU siloxane segment and the reduction of the melt surface tension to 28.5 mN / m by PFPE (38 mN / m for Comparative Example 2).

[0139] The holographic diffraction efficiency of Example 1 is 85.3%, which is significantly higher than that of Comparative Example 3 (60.5%), proving that the vinyl grafted nanoparticles are chemically anchored by UV curing (the binding energy is increased to 15 kJ / mol), and the core-shell structure optimizes the light scattering path (SiO 2 Shell refractive index 1.45, TiO 2 Core 2.5).

[0140] The energy consumption of 1.05 kW·h / 10,000 sheets in Example 1 is only 32.8% of that in Comparative Example 4 (3.2 kW·h), which is due to: gradient polymerization shortening the processing time in the high-temperature section (from 60 min to 15 min) and UV curing replacing traditional hot air drying (energy consumption reduced by 70%).

[0141] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser positioning anodized aluminum hot stamping adhesive, characterized in that: The back glue is formed into an interpenetrating network structure by in-situ polymerization of the following components by weight: 25-35 parts of modified polyurethane, 65-75 parts of acrylic resin, 3-5 parts of TiO2 / SiO2 core-shell nanoparticles and 0.5-1.2 parts of reactive perfluoropolyether interfacial compatibilizer. The storage modulus of the back glue at 80°C is 0.8*10 4 Pa·s-1.2*10 4 Pa·s.

2. The laser positioning electrochemical aluminum hot stamping adhesive as claimed in claim 1, characterized in that: The modified polyurethane is organosilicon-modified polyurethane, which is prepared by the reaction of isophorone diisocyanate, polycarbonate diol and gamma-aminopropyltriethoxysilane, wherein the siloxane chain segment accounts for 15-18% of the total mass of the polyurethane chain segment.

3. The laser positioning electrochemical aluminum hot stamping adhesive as claimed in claim 1, characterized in that: The mass ratio of TiO2 to SiO2 in TiO2 / SiO2 core-shell nanoparticles is 1:(1-2).

4. The laser positioning electrochemical aluminum hot stamping adhesive as claimed in claim 3, characterized in that: The surface of the TiO2 / SiO2 core-shell nanoparticles is grafted with vinyl, and the vinyl grafting rate is 85%-95%. The vinyl grafting makes the interface bonding strength between the nanoparticles and the resin matrix ≥15MPa.

5. The laser positioning electrochemical aluminum hot stamping adhesive as claimed in claim 1, characterized in that: The acrylic resin is a copolymer of methyl methacrylate-butyl acrylate-hydroxyethyl acrylate, and has a glass transition temperature of -10°C to 10°C and a hydroxyl value of 50-80 mg KOH / g.

6. The laser positioning electrochemical aluminum hot stamping adhesive as claimed in claim 1, characterized in that: The molecular weight of the reactive perfluoropolyether is 2000-5000 g / mol, the fluorine content is 50-65 wt %, and the reactive group thereof contains an acrylate double bond.

7. A method for preparing the laser positioning electrochemical aluminum hot stamping adhesive as claimed in any one of claims 1 to 6, characterized in that: The steps include: Step 1: Mix the modified polyurethane prepolymer and acrylic resin monomer, add reactive perfluoropolyether, heat to 60-80°C, stir and react for 30-60 minutes; Step 2: Add TiO2 / SiO2 core-shell nanoparticles to the mixture obtained in step 1, and perform ultrasonic dispersion treatment at 40kHz power 200W for 20-40min; Step 3: Gradient temperature rise in-situ polymerization: The first stage: 3-5℃ / min heating rate, heating to 75-85℃ and keeping warm for 30min; The second stage: heating at a rate of 8-10℃ / min to 115-125℃ and keeping warm for 15min; Phase 3: 365nm wavelength, 80mW / cm 2 Carry out UV curing treatment and irradiate for 10-20s.

8. The preparation method according to claim 7, characterized in that: During the third stage of UV curing, a pressure of 0.1-0.3 MPa is applied simultaneously.

9. The preparation method according to claim 7, characterized in that: In step 2, 0.1-0.5 wt % of a silane coupling agent is added to the mixture during ultrasonic dispersion.

10. The preparation method according to claim 7, characterized in that: The acrylic resin monomer comprises methyl methacrylate, butyl acrylate and hydroxyethyl acrylate in a mass ratio of (40-50):(30-40):(10-20).

Images