High-durability pressure-sensitive adhesive with low VOCs release and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a high-durability pressure-sensitive adhesive with low VOCs release and a preparation method thereof.The high-durability pressure-sensitive adhesive is prepared from, by weight, 50-80 parts of acrylate copolymer, 0.5-5 parts of cross-linking agent, 10-30 parts of tackifying resin, 1-10 parts of inorganic filler, 0.1-2 parts of antioxidant and 20-50 parts of solvent. Wherein the tackifying resin is at least one of hydrogenated petroleum resin and glycerol ester of rosin, and the inorganic filler is one of nanoscale silicon dioxide and calcium carbonate. Butyl acrylate is used as a main monomer, 2-ethylhexyl acrylate is used as a comonomer, acrylic acid is used as a functional monomer, benzoyl peroxide is used as an initiator, free radical polymerization is carried out at the temperature of 60-85 DEG C under the protection of nitrogen for 4-8 hours, and a copolymer chain with the molecular weight distribution index (PDI) smaller than or equal to 2.5 is formed, so that the viscosity and elasticity of colloid can be balanced; the peeling strength and the weather resistance are improved, and the colloid is prevented from being too soft or embrittled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials, in particular to a high durability pressure sensitive adhesive with low VOCs release and a preparation method thereof. BACKGROUND

[0002] Pressure sensitive adhesive is a special adhesive that has long-lasting adhesion at room temperature and can be quickly bonded to the surface of the adherend with only slight pressure. It appears as a solid or semi-solid state and does not require solvent dissolution or heating activation. It can achieve adhesion through intermolecular forces under contact pressure. The mechanism of pressure sensitive adhesive is based on surface energy matching and interface diffusion. When in contact with the substrate, the adhesive layer penetrates into the micro concave-convex structure through slight deformation, forming physical anchoring, while maintaining sufficient cohesive strength to avoid residue or displacement. It is widely used in fields such as packaging tape, label stickers, medical dressings, and electronic device protection films. According to the substrate and performance requirements, it can be designed as water-based, solvent-based, and hot melt systems, and has the characteristics of convenience, environmental protection, and strong adaptability. It is an indispensable functional material in modern industry and daily life.

[0003] In the existing preparation process of pressure sensitive adhesive, the use of butyl acrylate and isooctyl ester can easily cause the glass transition temperature to deviate to below-50℃ or above-30℃, resulting in the problem of over-softness and brittleness of the adhesive. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a high durability pressure sensitive adhesive with low VOCs release and a preparation method thereof, which solves the problem of over-softness and brittleness of the adhesive caused by the use of butyl acrylate and isooctyl ester in the existing preparation process of pressure sensitive adhesive, which can easily cause the glass transition temperature to deviate to below-50℃ or above-30℃.

[0005] To achieve the above purpose, the present application realizes the following technical scheme: a high durability pressure sensitive adhesive with low VOCs release, comprising the following components by weight: 50-80 parts of acrylate copolymer, 0.5-5 parts of crosslinking agent, 10-30 parts of tackifying resin, 1-10 parts of inorganic filler, 0.1-2 parts of antioxidant, and 20-50 parts of solvent, wherein the tackifying resin is at least one of hydrogenated petroleum resin and rosin glyceride, and the inorganic filler is one of nano-sized silicon dioxide and calcium carbonate.

[0006] By the above technical scheme: firstly, butyl acrylate, isooctyl acrylate and functional monomer acrylate are dissolved in ethyl acetate medium, benzoyl peroxide is used as free radical initiator, and controllable polymerization is carried out at 60-85℃ temperature interval for 4-8 hours under the protection of inert atmosphere, so as to obtain prepolymer solution with molecular weight polydispersity index ≤2.5; then, nano-sized silica particles modified by silane treatment agent and hydrogenated petroleum resin are introduced, and high shear dispersion equipment with 500-1000 revolutions per minute is used to treat for 1-2 hours to realize uniform distribution of nanoparticles and interface strengthening; subsequently, hexamethylene diisocyanate trimer is added as crosslinking component, and curing reaction is carried out at 50-80℃ control temperature and 200-500 revolutions per minute stirring speed for 1-3 hours, so as to promote chemical crosslinking of isocyanate groups and hydroxyl / carboxyl groups on polymer chain to build three-dimensional network structure, and hindered phenol and phosphite composite antioxidant are compounded according to 1:1 to 3:1 mass ratio, which can block the material oxidation degradation path.

[0007] Preferably, the acrylate copolymer is copolymerized by the following monomers: 40-60wt% of butyl acrylate, 20-40wt% of isooctyl acrylate and 1-10wt% of functional monomer, wherein the functional monomer is at least one selected from acrylate, hydroxyethyl methacrylate and acrylamide.

[0008] Preferably, the crosslinking agent is one of isocyanate crosslinking agent and epoxy crosslinking agent, and the addition amount is 0.5%-3% of the weight of the acrylate copolymer.

[0009] Preferably, the inorganic filler is nano-sized silica modified by silane coupling agent, the particle size range is 10-100nm, and the addition amount is 2-5 parts.

[0010] Preferably, the antioxidant is a compounded system of hindered phenol antioxidant and phosphite antioxidant, the mass ratio is 1:1-3:1, the solvent is at least one of ethyl acetate, acetone and alcohol solvent, and the VOCs content is ≤50ppm.

[0011] Preferably, a preparation method of low VOCs release high durability pressure sensitive adhesive comprises the following steps:

[0012] S1, polymerize acrylate monomers and functional monomers in a solvent to prepare an acrylate copolymer solution;

[0013] S2, add tackifying resin, inorganic filler and antioxidant to the solution obtained in S1 in sequence, and stir and mix while keeping the temperature at 40-60℃;

[0014] S3, add crosslinking agent and continue stirring for 1-3 hours;

[0015] S4, coating the mixed glue solution on the substrate, drying by stepwise temperature rising, and winding.

[0016] Preferably, the polymerization reaction temperature in S1 is 60-85℃, the reaction time is 4-8 hours, and the initiator is one of benzoyl peroxide and azobisisobutyronitrile.

[0017] Preferably, in S2, a high-speed dispersing machine is used to stir at a speed of 500-1000 rpm for 1-2 hours, so that the inorganic filler and the tackifying resin are uniformly dispersed in the acrylic ester copolymer solution.

[0018] Preferably, in S3, the crosslinking reaction temperature is controlled at 50-80℃, and the stirring speed is 200-500 rpm.

[0019] Preferably, in S4, the stepwise temperature rising drying is divided into three stages:

[0020] The first stage: 50-60℃ drying for 1-2 minutes,

[0021] The second stage: 80-90℃ drying for 2-3 minutes,

[0022] The third stage: 100-120℃ drying for 0.5-1 minute.

[0023] The present application provides a low VOCs release high durability pressure sensitive adhesive and a preparation method thereof. The present application has the following beneficial effects:

[0024] 1. In the present application, butyl acrylate is used as the main monomer, isooctyl acrylate is used as the comonomer, acrylic acid is used as the functional monomer, benzoyl peroxide is used as the initiator, and free radical polymerization is carried out under nitrogen protection at 60-85℃ for 4-8 hours. The molar ratio of butyl acrylate to isooctyl acrylate is controlled at (3:1)-(1:1), the glass transition temperature (Tg) is controlled in the range of -45℃ to -30℃, and the copolymer chain with a molecular weight distribution index (PDI) ≤2.5 is formed, so that the balance between colloid viscosity and elasticity can be achieved, the peeling strength and weather resistance can be improved, and the effect of avoiding colloid softening or embrittlement can be achieved.

[0025] 2. In the present application, nano-silicon dioxide and silane coupling agent are dispersed in a solution with a volume ratio of ethanol to water of 9:1, and surface modification is carried out by ultrasonic dispersion at 60-80℃ for 1-2 hours. Then, high-speed stirring is carried out at 500-1000 rpm for 1-2 hours at 40-60℃, and an ultrasonic probe is used to break the agglomerates, so that the nano-silicon dioxide is uniformly dispersed in the acrylic ester copolymer solution, and the spacing between fillers is <50 nm. Thus, the effect of enhancing the interfacial bonding force, improving the durability and environmental performance of the pressure sensitive adhesive through crack deflection and solvent adsorption, and improving the tensile toughness can be achieved.

[0026] 3、The present application can avoid local concentration too high leading to gelation, improve cohesive strength and aging resistance, and keep high adhesive force retention rate of pressure sensitive adhesive after humid heat aging by adding isocyanate crosslinking agent into the solution at a rate of 0.5-2 mL / min after the copolymer solution is cooled to 50-80℃, synchronously stirring at a medium speed of 200-500 rpm, adding in stages and controlling the reaction temperature and stirring speed, and making -NCO groups react with -OH / -COOH groups in the copolymer to build a three-dimensional network structure.

[0027] 4、The present application can achieve the effects of capturing free radicals by hindered phenol, decomposing hydroperoxide by phosphite antioxidant, synergistically inhibiting oxidative degradation, prolonging oxidation induction period, and improving long-term stability of pressure sensitive adhesive by adopting a complex system of hindered phenol antioxidant and phosphite antioxidant with a mass ratio of 1:1-3:1, and adding the solution into the glue solution after pre-dissolving in a low VOCs solvent and stirring at 500 rpm for 30 minutes to form a homogeneous solution at 40-60℃. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A process flow chart of a preparation method of a low VOCs releasing high durability pressure sensitive adhesive according to the present application is provided. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] Please refer to the drawings of the present application Figure 1 The present application provides a low VOCs releasing high durability pressure sensitive adhesive, which comprises the following components by weight: 50-80 parts of acrylate copolymer, 0.5-5 parts of crosslinking agent, 10-30 parts of tackifying resin, 1-10 parts of inorganic filler, 0.1-2 parts of antioxidant, and 20-50 parts of solvent, wherein the tackifying resin is at least one of hydrogenated petroleum resin and rosin glyceride, and the inorganic filler is one of nano-sized silicon dioxide and calcium carbonate.

[0031] Specifically, the acrylate copolymer is prepared by solution polymerization: butyl acrylate (40-60wt%), isooctyl acrylate (20-40wt%) and functional monomer (1-10wt%) are mixed in ethyl acetate solvent, wherein the functional monomer is selected from acrylic acid, and benzoyl peroxide (0.1-0.5wt%) is used as an initiator, and the mixture is reacted at 60-85°C for 4-8 hours under nitrogen protection to form a copolymer solution with a molecular weight distribution index of ≤2.5; then nano-silica (particle size 10-100nm, addition amount 2-5 parts) and hydrogenated petroleum resin modified by silane coupling agent are added, and the mixture is mixed at a high speed of 500-1000rpm for 1-2 hours to ensure uniform dispersion of the fillers to improve the interfacial bonding force; then isocyanate crosslinking agent (HDI trimer, 0.5-3%) is added in stages, and the mixture is reacted at 50-80°C and stirred at 200-500rpm for 1-3 hours, so that the -NCO groups are crosslinked with the -OH / -COOH groups in the copolymer to form a three-dimensional network structure, and at the same time, hindered phenolic / phosphite antioxidants are introduced with a mass ratio of 1:1-3:1 to inhibit oxidative degradation.

[0032] The acrylate copolymer is copolymerized from the following monomers: butyl acrylate 40-60wt%, isooctyl acrylate 20-40wt%, and functional monomer 1-10wt%, wherein the functional monomer is at least one selected from acrylic acid, hydroxyethyl methacrylate and acrylamide.

[0033] Specifically, butyl acrylate (40-60wt%) is used as the main monomer to give the glue flexibility and initial adhesion; isooctyl acrylate (20-40wt%) is used as the comonomer to improve weather resistance and cohesive strength through the steric hindrance effect of long-chain alkyl; the functional monomer (1-10wt%) is preferably acrylic acid, hydroxyethyl methacrylate or acrylamide, wherein the carboxyl group of acrylic acid can react with the isocyanate group of the subsequent crosslinking agent to form a urethane bond, the hydroxyl group of hydroxyethyl methacrylate enhances the interfacial adhesion force through hydrogen bonding, and the amide group of acrylamide improves the anti-creep performance through intermolecular hydrogen bonding. During polymerization, benzoyl peroxide (0.1-0.5wt%) is used as an initiator, and the reaction is carried out at 60-85°C for 4-8 hours under nitrogen protection, forming a copolymer chain with a molecular weight distribution index (PDI) ≤2.5 through free radical polymerization, wherein the molar ratio of butyl acrylate to isooctyl acrylate is optimized to (3:1)-(1:1) to ensure that the glass transition temperature (Tg) is controlled in the range of -45°C to -30°C, balancing the viscosity and elasticity; experiments show that when the proportion of butyl acrylate is >60%, the glue is too soft, resulting in a holding power of <60h (GB / T4851); and when the amount of functional monomer is <1%, the crosslinking density is insufficient, and the peel strength is only 6.8N / 25mm; and when the amount of functional monomer is >10%, the glue layer is brittle (elongation at break <200%) due to excessive crosslinking; through Fourier transform infrared spectroscopy (FTIR) verification, the copolymer appears an ester group characteristic peak at 1720cm -1 , and the carboxyl group peak (1690cm -1 ) of acrylic acid gradually weakens with crosslinking reaction, confirming that the -NCO / -COOH reaction is complete; finally, the monomer ratio is optimized as butyl acrylate 50%, isooctyl acrylate 35%, and acrylic acid 5%, and the obtained pressure-sensitive adhesive has a storage modulus of 0.5MPa at 25°C, a peel strength of 12.3N / 25mm, and a holding power retention rate ≥95% after 500h of damp heat aging at 85°C / 85%RH.

[0034] The crosslinking agent is one of isocyanate crosslinking agent and epoxy crosslinking agent, and the amount of addition is 0.5%-3% of the weight of the acrylate copolymer.

[0035] Specifically, after the copolymer solution is cooled to 50-80°C, the crosslinking agent is added to the solution at a rate of 0.5-2mL / min, and synchronous stirring is carried out at a medium speed of 200-500rpm to avoid gelation caused by local high concentration; the isocyanate crosslinking agent reacts with the hydroxyl and carboxyl groups in the copolymer through its -NCO group to form urethane bonds and amide bonds, respectively, to build a three-dimensional crosslinking network; and the epoxy crosslinking agent reacts with the hydroxyl / carboxyl groups through ring opening of the epoxy group to form ether bond or ester bond crosslinking points.

[0036] The inorganic filler is nano-silica modified by silane coupling agent, with particle size range of 10-100 nm, and addition amount of 2-5 parts.

[0037] Specifically, the nano-silica with particle size of 10-100 nm and BET specific surface area of 150-300 m 2 / g is mixed with silane coupling agent in ethanol solution, with the amount of silane coupling agent being 1%-3% of the mass of the filler, and the volume ratio of ethanol to water being 9:1; then the mixture is ultrasonically dispersed at 60-80°C (frequency 40 kHz, power 300 W) for 1-2 hours, so that the -Si-OCH2CH3 groups of the silane are converted to -Si-OH through hydrolysis and condensation reaction, and condensed with the surface hydroxyl groups (-OH) of the silica to form stable Si-O-Si bonds, while the organic end (-NH2) of the coupling agent is exposed on the surface of the filler, giving it polarity compatibility with the acrylate copolymer, the silane coupling agent inhibits interfacial peeling through chemical bonding, and the nano-filler enhances durability and environmental performance through crack deflection and solvent adsorption.

[0038] The antioxidant is a compounded system of hindered phenolic antioxidant and phosphite antioxidant, with mass ratio of 1:1-3:1, and the solvent is at least one of ethyl acetate, acetone and alcohol, with VOCs content ≤50 ppm.

[0039] Specifically, the antioxidant is a compounded system of hindered phenolic Irganox1010 and phosphite Irgafos168, with mass ratio of 1:1-3:1, which is uniformly dispersed by pre-dissolving in low VOCs solvent, wherein the low VOCs solvent is ethyl acetate solution with VOCs ≤50 ppm, and then the mixture is stirred at 500 rpm for 30 minutes at 40-60°C to form a homogeneous solution, and then the glue solution is added, so that the phenolic hydroxyl group of the hindered phenol captures free radicals (·OH / RO·) to block the initiation of oxidation chain, and the P=O bond of the phosphite decomposes hydroperoxide (ROOH) to inhibit chain growth, so that the oxidation induction period is extended from 60 minutes (single antioxidant) to 180 minutes.

[0040] A preparation method of a high-durability pressure-sensitive adhesive with low VOCs release, comprising the following steps:

[0041] S1, polymerizing acrylate monomers and functional monomers in a solvent to prepare an acrylate copolymer solution;

[0042] S2, adding tackifying resin, inorganic filler and antioxidant to the solution obtained in S1 in sequence, and stirring and mixing while maintaining the temperature at 40-60°C;

[0043] S3, adding crosslinking agent and continuing to stir and react for 1-3 hours;

[0044] S4, coating the mixed glue solution on the substrate, drying by stepwise temperature rise, and winding.

[0045] Specifically, S1: butyl acrylate (40-60wt%), isooctyl acrylate (20-40wt%) and functional monomer (1-10wt%) are dissolved in ethyl acetate with VOCs content ≤50ppm, benzoyl peroxide (0.1-0.5wt%) is added as initiator, and the reaction is carried out at 60-85℃ for 4-8 hours under nitrogen protection, to generate a copolymer solution with molecular weight distribution index (PDI) ≤2.5 by free radical polymerization, wherein the carboxyl group (-COOH) of the acrylic acid provides active sites for subsequent crosslinking;

[0046] S2: the S1 solution is cooled to 40-60℃, and nano-silica modified by hydrogenated petroleum resin and silane coupling agent (KH-550) and hindered phenol / phosphite compound antioxidant are added in sequence, and stirred at 500-1000rpm for 1-2 hours, so that the -Si-O- bond of the modified filler is combined with the polar groups of the resin to form a uniformly dispersed system, wherein TEM shows that the spacing between fillers is <50nm;

[0047] S3: HDI trimer crosslinking agent is added in stages, and the reaction is carried out at 50-80℃ and 200-500rpm for 1-3 hours, to build a crosslinking network by the reaction of -NCO with -OH / -COOH of the copolymer, wherein FTIR shows that the peak at 2270cm -1 disappears, and the crosslinking density reaches 1.1×10 -4 mol / cm 3 , and the reaction temperature is optimized by experiment to avoid local gelation and control the viscosity at 3000-5000cP;

[0048] S4: the glue solution is coated on the corona-treated PET substrate by a slot coater with a wet film thickness of 50-150μm, and dried in three stages, wherein the first stage is to remove 70% of the low-boiling-point solvents, the second stage triggers pre-crosslinking, and the third stage completes the final crosslinking by infrared radiation, so that the residual solvent is ≤0.3% and the VOCs release is ≤80μg / g by matching the solvent boiling point with the crosslinking activation energy through gradient temperature rise.

[0049] In S1, the polymerization reaction temperature is 60-85℃, the reaction time is 4-8 hours, and the initiator is one of benzoyl peroxide and azobisisobutyronitrile.

[0050] Specifically, benzoyl peroxide or azobisisobutyronitrile is selected as the initiator, and the addition amount is 0.1%-0.5% of the total mass of the monomers. The mixture of monomers, i.e. a mixture of 40-60wt% butyl acrylate, 20-40wt% isooctyl acrylate and 1-10wt% functional monomers, is put into a reaction kettle with VOCs content ≤50ppm ethyl acetate solvent under nitrogen protection. The temperature is programmed to 60-85°C, among which the benzoyl peroxide is suitable for 70-85°C, and the azobisisobutyronitrile is suitable for 60-75°C. The reaction time is 4-8 hours. Free radical polymerization generates a copolymer with a number average molecular weight of 8×10 4 -1.2×10 5 , a molecular weight distribution index ≤2.5, and a carboxyl / hydroxyl functional group conversion rate of the functional monomer ≥98%; the benzoyl peroxide is uniformly cleaved by heat to generate benzoyl oxygen free radicals (·OOCPh), which initiate the opening of the double bonds of the acrylate monomers to form growing chains, and the molecular weight is regulated by chain transfer and termination; the carboxyl groups of the functional monomers are distributed in the side groups of the segments in the polymerization, providing anchoring sites for subsequent crosslinking (XPS shows that the COOH content has an error of <2% compared with the feeding ratio), and meanwhile the shielding effect of the isooctyl ester long chain inhibits the self-association of the carboxyl groups, ensuring the initial tackiness of the glue.

[0051] In S2, a high-speed disperser is used to stir and mix the inorganic filler and the tackifying resin in the acrylate copolymer solution at a speed of 500-1000rpm for 1-2 hours.

[0052] Specifically, an anchor high-speed disperser is used to stir at a constant temperature of 40-60°C at a speed of 500-1000rpm for 1-2 hours, among which the fillers are pre-mixed at a low speed of 500rpm for the first 30 minutes to avoid dust, and then the speed is increased to 1000rpm for high-speed dispersion. During this process, the Reynolds number Re is >2000 and enters the turbulent flow state, and at the same time, an ultrasonic probe is used to act for 2 minutes every 10 minutes to break the nano-silica agglomerates through cavitation effect, so that the particle size is reduced from the initial 200nm to 50nm. The dispersion system contains nano-silica modified by silane coupling agent (KH-550), hydrogenated petroleum resin and hindered phenol / phosphite compound antioxidant, and the mass ratio of the three is optimized to (5:10:1)-(5:30:3). During this process, the shear stress generated by high speed overcomes the agglomeration energy of the fillers, so that the nano-particles are depolymerized and embedded in the resin phase. Meanwhile, the -Si-O-Si- network of the modified filler and the alkyl chain of the resin form an interpenetrating structure through hydrophobic interaction and hydrogen bonding. The uniformly dispersed nano-particles dissipate energy through crack bridging and crack branching, so that the tensile toughness is improved to 25MJ / m 3 .

[0053] In S3, the crosslinking reaction temperature is controlled at 50-80°C, and the stirring speed is 200-500rpm.

[0054] Specifically, after the addition of HDI trimer crosslinker, the reaction is continued at 50-80 °C with a stirring speed of 200-500 rpm for 1-3 hours, with the first 30 minutes of low-speed stirring (shear rate ) of 200 rpm to ensure uniform diffusion of the crosslinker, and then the stirring speed is increased to 500 rpm to accelerate the condensation reaction of the -NCO groups with the hydroxyl and carboxyl groups in the copolymer, and the reaction is terminated when the -NCO characteristic peak at 2270 cm -1 -1 attenuates to <5% intensity, as monitored by online FTIR; in this process, the -NCO groups of the HDI trimer form urethane bonds with the -OH groups and amide bonds with the -COOH groups in the copolymer, both forming an interpenetrating network structure, and moderate stirring (300-400 rpm) balances the diffusion control and reaction control, avoiding local overcrosslinking.

[0055] The stepwise temperature increase drying in S4 is divided into three stages:

[0056] First stage: drying at 50-60 °C for 1-2 minutes,

[0057] Second stage: drying at 80-90 °C for 2-3 minutes,

[0058] Third stage: drying at 100-120 °C for 0.5-1 minute.

[0059] Specifically, in the first stage, a hot air circulation system with a horizontal wind speed of 3-5 m / s is used to quickly remove 70% of the solvent by taking advantage of the low boiling point of ethyl acetate, and at the same time, the surface temperature gradient of the adhesive layer is monitored by dynamic infrared thermal imaging to be ≤5 °C to avoid violent boiling to form micropores, and SEM shows that the porosity is <2%, preferentially removing the solvent to form porous channels and avoid affecting the solvent in subsequent crosslinking.

[0060] Second stage: switching to low wind speed (1-2 m / s) and gradient temperature increase (2 °C / min) to trigger the pre-crosslinking reaction of the HDI trimer crosslinker, with a crosslinking initiation temperature of 75 °C, and the residual solvent acts as a temporary plasticizer through the solvation effect to promote the migration of -NCO groups to the active sites of the copolymer -OH / -COOH, and fluorescence labeling shows that the diffusion rate is increased by 3 times, and the crosslinking density is increased from 0.3 × 10 -4 mol / cm 3 to 0.9 × 10 -4 mol / cm 3 , and the residual solvent is reduced to 3%-5% in this stage.

[0061] Third stage: short-wave infrared radiation is used, with a radiation wavelength of 2-5 μm and a power density of 2 W / cm 2 , to direct heat to the inside of the adhesive layer, so that the activation energy barrier (Ea = 45 kJ / mol) of the crosslinking reaction is broken, and the crosslinking density jumps to 1.2 × 10-4 mol / cm 3 , synchronously expelling high-boiling by-products in the form of nanobubbles (particle size < 50 nm) through the micro-explosion effect, with the final residual solvent ≤ 0.3% and VOCs release ≤ 80 pg / g.

[0062] Example One: High Tack Formula

[0063] 1. Ingredients:

[0064] Acrylate copolymer: 70 parts,

[0065] Crosslinker: HDI trimer 1.5 parts (2.1% of copolymer),

[0066] Tackifying resin: hydrogenated petroleum resin 20 parts,

[0067] Inorganic filler: KH-550 modified nano-SiO2 3 parts (particle size 30 nm),

[0068] Antioxidant: Irganox 1010 and Irgafos 168 compounded 0.8 parts (mass ratio 2:1),

[0069] Solvent: ethyl acetate 30 parts (VOCs ≤ 50 ppm).

[0070] 2. Preparation process:

[0071] S1 : Mix 350 g of butyl acrylate, 245 g of isooctyl acrylate, 35 g of acrylic acid, and 300 g of ethyl acetate, add 3.15 g of benzoyl peroxide, and react at 60°C for 6 hours under nitrogen protection to obtain a copolymer solution with PDI = 2.1 (Mn = 9.8 x 10 4 );

[0072] S2: Cool to 50°C, add 200 g of hydrogenated petroleum resin, 30 g of modified nano-SiO2, and 8 g of antioxidant, and disperse at 800 rpm for 1.5 hours with high-speed dispersion and ultrasonic assistance. TEM shows that the spacing between fillers is 40 nm;

[0073] S3: Add 15 g of HDI trimer in three stages, stir at 300 rpm at 60°C for 2 hours, and verify the disappearance of the -NCO peak by FTIR. The crosslinking density is 1.05 x 10 -4 mol / cm 3 ;

[0074] S4: Coated on PET substrate (wet thickness 100 μm), first dried at 50°C stage using hot air circulation system with transverse air speed 3-5 m / s for 2 minutes, real-time monitoring of glue layer temperature gradient ≤5°C by dynamic infrared thermal imaging, preferentially removing 70% of low boiling point ethyl acetate and forming porous channels; then switched to 85°C medium temperature stage, with 1-2 m / s low air speed combined with 2°C / min gradient heating for 3 minutes, triggering HDI trimer pre-crosslinking reaction, and promoting the diffusion of residual solvent auxiliary crosslinking agent through solvation effect; finally, using 2-5 μm wavelength short wave infrared radiation directional heating at 110°C high temperature stage for 1 minute, making the residual solvent ≤0.3%, VOCs release amount ≤80 μg / g, and simultaneously completing the final crosslinking.

[0075] 3. Performance:

[0076] Peeling strength: 12.5 N / 25 mm (GB / T 2792),

[0077] Adhesion retention: 72 h (GB / T 4851),

[0078] VOCs release amount: 75 μg / g (ISO 16000-6),

[0079] Adhesion retention rate after 500 h of damp heat aging: 96%.

[0080] 4. Application:

[0081] Suitable for automotive interior parts bonding, resistant to -40°C to 120°C temperature fluctuations.

[0082] Example Two: High Temperature Resistant Formulation

[0083] 1. Ingredients:

[0084] Acrylate copolymer: 65 parts,

[0085] Crosslinking agent: epoxy crosslinking agent 1.8 parts,

[0086] Tackifying resin: glycerol ester of rosin 25 parts,

[0087] Inorganic filler: modified nano-CaCO3 4 parts (particle size 80 nm),

[0088] Antioxidant: Irganox 1076 and phosphite compound 1.2 parts (3:1),

[0089] Solvent: acetone / ethyl acetate (1:1) 35 parts.

[0090] 2. Preparation process:

[0091] S1: 292.5 g of butyl acrylate, 260 g of isooctyl acrylate, 32.5 g of hydroxyethyl methacrylate, and 350 g of mixed solvent, 2.93 g of azobisisobutyronitrile is added, and reacted at 73°C for 7 hours, PDI = 1.9;

[0092] S2: 250 g of rosin glyceride and 40 g of nano-CaCO3 are added, and dispersed at 1000 rpm for 2 hours, and SEM shows no agglomeration;

[0093] S3: 18 g of epoxy crosslinking agent is added in two portions, and reacted at 70°C for 2.5 hours at 400 rpm, and DSC shows that the Tg is raised to -28°C;

[0094] S4: First, dry at 55°C for 2 minutes in the initial section with a hot air circulation system with a horizontal wind speed of 4-6 m / s, quickly remove 65% of the ethyl acetate solvent and form a through-pore structure with a pore size of 30-50 nm, then enter the middle section at 90°C, switch to a laminar flow mode with a wind speed of 0.5-1.5 m / s and assist with a 2.5°C / min programmed temperature rise, trigger the ring-opening reaction of the epoxy crosslinking agent for 2.5 minutes, and use the plasticizing effect of the residual solvent to promote the uniformization of the crosslinking network; finally, use 3-6 μm mid-infrared radiation directional heating for 1 minute at 115°C in the final section, simultaneously achieve crosslinking activation energy breakthrough and micro-nano bubble directional blasting, reduce the residual solvent to 0.22%, VOCs release ≤65 μg / g, and form an interpenetrating network structure.

[0095] 3. Performance:

[0096] Thermal weight loss rate at 180°C: ≤2% (TGA),

[0097] Shear strength: 0.85 MPa (ASTM D1002),

[0098] Temperature resistance rating: -50°C to 150°C,

[0099] Yellowing index Δb after 1000h of UV aging: 1.2,

[0100] 4. Application: High-temperature packaging of electronic components, suitable for LED heat dissipation substrates.

[0101] Example Three: Low VOCs environmentally friendly formula

[0102] 1. Ingredients:

[0103] Acrylate copolymer: 60 parts,

[0104] Crosslinking agent: HDI trimer 0.9 parts,

[0105] Tackifying resin: hydrogenated petroleum resin 15 parts,

[0106] Inorganic filler: modified nano-SiO2 2.5 parts (particle size 15 nm),

[0107] Antioxidant: Irganox 1330 compounded with phosphite 0.5 parts (1:1),

[0108] Solvent: ethyl acetate 20 parts (VOCs ≤ 30 ppm).

[0109] 2. Preparation process:

[0110] S1: 330 g of butyl acrylate, 180 g of isooctyl acrylate, 30 g of acrylamide were mixed with 200 g of solvent, 2.7 g of benzoyl peroxide was initiated, and reacted at 85°C for 5 hours. FTIR showed that the characteristic peak of amide group was 1640 cm -1 ;

[0111] S2: Add 150 g of resin and 25 g of nano-SiO2, disperse at 700 rpm for 1 hour;

[0112] S3: Pump in 9 g of HDI trimer, and react at 55°C, 250 rpm for 3 hours, the viscosity is stable at 4200 cP;

[0113] S4: First, use pulsed hot air circulation at 50°C initial stage with a horizontal wind speed of 3-4 m / s for 1.5 minutes to remove 72% of ethyl acetate solvent and form a honeycomb-like microporous structure with a pore size of 10-30 nm; then enter the 80°C middle stage, switch to laminar flow mode with a wind speed of 0.8-1.2 m / s and apply a gradient heating of 2°C / min for 3 minutes to trigger the formation of a pre-crosslinked network; finally, use 4-7 μm medium-short wave infrared focused radiation directional impact drying at 105°C final stage for 0.8 minutes to break through the glass transition temperature and trigger the nano-scale solvent micro-explosion effect, and simultaneously complete the final crosslinking, and the residual solvent is only 0.18% detected by gas chromatography-mass spectrometry (GC-MS).

[0114] 3. Performance:

[0115] VOCs release: 52 μg / g,

[0116] Elongation at break: 320% (ASTM D638),

[0117] Antibacterial rate: 99.5% (ISO 22196),

[0118] Adhesion decay rate after 100 cycles of peeling: ≤ 3%.

[0119] 4. Application: medical-grade breathable adhesive tape, meeting the requirements of ISO 10993 biocompatibility.

[0120] The experimental results of the example are shown in the following figure:

[0121]

[0122]

[0123] According to the above experiments, the present invention has the following effects:

[0124] 1. Improved cross-linking efficiency: In Example 1, by adding HDI trimer in stages and controlling stirring at a medium speed, the cross-linking density is increased by 50% compared with the prior art, and the peel strength is increased from 8.2N to 12.5N while avoiding embrittlement.

[0125] 2. VOCs emission reduction: Example 3 uses a low molecular weight copolymer and an ultra-low solvent residue drying process, which reduces VOCs emissions by 65%, meeting the strict environmental protection standards in the medical field.

[0126] 3. Improved temperature resistance: Example 2 introduces epoxy crosslinker and hydroxyethyl methacrylate to increase the glass transition temperature of the material from -35°C to -28°C, allowing it to withstand high temperatures of 150°C, making it suitable for high-temperature electronic scenarios.

[0127] 4. Interface strengthening mechanism: All examples use silane coupling agent to modify the filler to increase the tensile toughness to 25MJ / m 3 , while the existing technology is only 15MJ / m 3 , the wet heat aging adhesion retention rate is >90%.

[0128] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-durability pressure-sensitive adhesive with low VOCs release, characterized in that: The invention comprises the following components in parts by weight: 50-80 parts of acrylate copolymer, 0.5-5 parts of crosslinking agent, 10-30 parts of tackifying resin, 1-10 parts of inorganic filler, 0.1-2 parts of antioxidant, and 20-50 parts of solvent, wherein the tackifying resin is at least one of hydrogenated petroleum resin and rosin glycerol ester, and the inorganic filler is one of nano-silicon dioxide and calcium carbonate.

2. The high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: The acrylic ester copolymer is copolymerized by the following monomers: 40-60 wt% butyl acrylate, 20-40 wt% isooctyl acrylate, and 1-10 wt% functional monomer, wherein the functional monomer is selected from at least one of acrylic acid, hydroxyethyl methacrylate, and acrylamide.

3. The high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: The crosslinking agent is one of an isocyanate crosslinking agent and an epoxy crosslinking agent, and its addition amount is 0.5%-3% of the weight of the acrylic ester copolymer.

4. The high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: The inorganic filler is nano-silicon dioxide whose surface is modified by a silane coupling agent, with a particle size range of 10-100 nm and an addition amount of 2-5 parts.

5. The high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: The antioxidant is a compound system of a hindered phenol antioxidant and a phosphite antioxidant, with a mass ratio of 1:1-3:

1. The solvent is at least one of ethyl acetate, acetone and alcohol solvents, and the VOCs content is ≤50ppm.

6. A method for preparing a high-durability pressure-sensitive adhesive with low VOCs release, characterized in that: A high-durability pressure-sensitive adhesive with low VOCs release according to any one of claims 1 to 5, comprising the following steps: S1, polymerizing an acrylate monomer and a functional monomer in a solvent to prepare an acrylate copolymer solution; S2. Add tackifying resin, inorganic filler and antioxidant to the solution obtained in S1 in sequence, and stir and mix while maintaining the temperature at 40-60°C; S3, add cross-linking agent, continue stirring and react for 1-3 hours; S4. Apply the mixed adhesive solution to the substrate, dry it by step-by-step heating, and then roll it up.

7. The method for preparing a high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: The polymerization reaction temperature in S1 is 60-85° C., the reaction time is 4-8 hours, and the initiator is one of benzoyl peroxide and azobisisobutyronitrile.

8. The method for preparing a high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: In S2, a high-speed disperser is used to stir and mix at a rotation speed of 500-1000 rpm for 1-2 hours to uniformly disperse the inorganic filler and the tackifying resin in the acrylate copolymer solution.

9. The method for preparing a high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: In S3, the cross-linking reaction temperature is controlled at 50-80°C, and the stirring speed is 200-500 rpm.

10. The method for preparing a high-durability pressure-sensitive adhesive with low VOCs release according to claim 1, characterized in that: S4 medium-step heating drying is divided into three stages: The first stage: drying at 50-60℃ for 1-2 minutes, The second stage: drying at 80-90℃ for 2-3 minutes, The third stage: drying at 100-120℃ for 0.5-1 minute.

Images