Low-dielectric ultraviolet curing adhesive based on modified polyphenyl ether resin as well as preparation method and application of low-dielectric ultraviolet curing adhesive

Abstract

The invention belongs to the technical field of organic thin films, and relates to a low-dielectric-coefficient ultraviolet curing adhesive based on modified polyphenyl ether resin as well as a preparation method and application of the low-dielectric-coefficient ultraviolet curing adhesive. The ultraviolet curing adhesive is prepared from the following components in parts by weight: 5 to 10 parts of polyphenyl ether resin, 10 to 20 parts of (methyl) acrylic monomer containing a benzene ring, 45 to 65 parts of monofunctional (methyl) acrylate containing a long carbon chain, 20 to 30 parts of bifunctional / polyfunctional (methyl) acrylate containing a long carbon chain and 1 to 10 parts of photo-crosslinking initiator. According to the invention, stable dispersion of the polyphenyl ether resin in an acrylic acid system is realized by introducing a (methyl) acrylic acid monomer containing a benzene ring and utilizing a pi-pi conjugation effect and a polarity matching principle, and the mechanical property of the ultraviolet curing adhesive formula can be improved by adding 5-10 parts of the polyphenyl ether resin; therefore, the problem that the existing low-dielectric ultraviolet curing adhesive is poor in mechanical property is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic thin films and relates to a low-dielectric-consistent ultraviolet-curing adhesive based on modified polyphenylene ether resin, and a preparation method and application thereof. Background Art

[0002] In the information age, the stability and reliability of electronic devices during use are among the most critical issues. The organic molecules in electronic devices are easily degraded by moisture and oxygen in the air, leading to severe performance degradation or even device damage. Therefore, the most effective way to prevent organic molecules from being damaged by moisture and oxygen is to use polymer films to completely block contact between the organic molecules and air, forming a tight package.

[0003] With the advent of the 5G communications era, devices are placing even stricter demands on the dielectric constant of encapsulation materials. Due to the high transmission frequency of 5G communications, signals are susceptible to attenuation in the transmission medium, so encapsulation films typically require a dielectric constant of less than 3. However, the dielectric constant of traditional encapsulation media is often high; therefore, the development of polymer encapsulation materials with low dielectric constants and dielectric loss has become a focus of widespread industry attention. In addition to preventing water and oxygen from damaging the organic molecular materials within the device, encapsulation films must also possess other specialized properties. For example, films used to encapsulate organic light-emitting diodes (OLEDs) must have very high visible light transmittance to minimize absorption losses from the device's light. Furthermore, films encapsulating OLEDs also require a low dielectric constant, primarily because the encapsulation layer is located between the top-emitting organic electroluminescent metal electrode and the touchscreen conductive film above it. The advantage of a low dielectric constant lies in reducing the parasitic resistance and dielectric loss of the encapsulation layer, potentially improving the electrical properties of the encapsulation material, particularly its electrical insulation at high frequencies.

[0004] Inkjet printing is a mainstream coating method for thin-film encapsulation of OLED devices. Using an industrial-grade printhead, inkjet printing precisely deposits droplets of a functional encapsulating adhesive onto the substrate surface, forming a film. This process places stringent requirements on the material's viscosity, typically maintaining it within a range of 10-30 cps. Conventional low-viscosity, low-dielectric acrylic monomers are often designed with monofunctional structures and long carbon chains (such as lauryl acrylate). While these monomers effectively reduce system viscosity, excessive use can significantly weaken the crosslink density after curing, leading to deterioration in the mechanical properties of the encapsulation layer (such as tensile strength and Young's modulus). Furthermore, these monomers often contain amphiphilic groups (such as long hydrophobic chains and hydrophilic ester groups) in their molecular structures, exhibiting surfactant-like behavior. This not only reduces the ink's surface tension but can also cause uncontrolled droplet diffusion during printing, ultimately impacting film uniformity and process stability.

[0005] Furthermore, even when polyphenylene ether resins are modified with acrylate functional groups to impart photocurable activity, their solubility compatibility in low-K ink systems remains a significant challenge. For example, NORYL™ SA9000 resin (number-average molecular weight Mn = 2300) developed by Saudi Basic Industries Corporation (SABIC) exhibits high molecular chain rigidity and significantly different solubility parameters from those of long-chain monofunctional acrylates such as lauryl acrylate, limiting their compatibility. Experimental data show that when the addition of SA9000 resin to lauryl acrylate exceeds 2wt%, the system becomes turbid, a significant barrier to the application of polyphenylene ether resins in low-K acrylic materials.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a low dielectric constant UV-curing adhesive based on modified polyphenylene ether resin and its preparation method and application, so as to overcome the problem of poor mechanical properties of current low dielectric constant UV-curing adhesive. The object of the present invention is achieved through the following technical solutions: On the one hand, the present invention provides a low-dielectric UV-curing adhesive based on modified polyphenylene ether resin, which achieves stable dispersion of polyphenylene ether resin in acrylic system by introducing (meth) acrylic monomer containing benzene ring and utilizing π-π conjugation effect and polarity matching principle.

[0008] Specifically, the low-dielectric UV-curable adhesive includes the following components in parts by weight: 5 to 10 parts of polyphenylene ether resin, 10 to 20 parts of a (meth)acrylic monomer containing a benzene ring, 45 to 65 parts of a monofunctional (meth)acrylate containing a long carbon chain, 20 to 30 parts of a difunctional / polyfunctional (meth)acrylate containing a long carbon chain, and 1 to 10 parts of a photocrosslinking initiator. It should be noted that, in principle, the components of the above raw materials can be controlled within the above weight ranges. For example, the weight of the polyphenylene ether resin can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., the weight of the monofunctional (meth)acrylate containing a long carbon chain can be 45 parts, 48 ​​parts, 50 parts, 55 parts, 58 parts, 60 parts, 62 parts, 65 parts, etc., the weight of the difunctional / polyfunctional (meth)acrylate containing a long carbon chain can be 20 parts, 22 parts, 25 parts, 26 parts, 28 parts, 30 parts, etc., and the weight of the photocrosslinking initiator can be 1 part, 3 parts, 5 parts, 6 parts, 8 parts, 10 parts, etc., which are not listed one by one here.

[0009] Specifically, the monofunctional (meth)acrylate containing a long carbon chain includes one of lauryl methacrylate, isooctyl methacrylate, isononyl acrylate, stearic acid acrylate, and isodecyl acrylate.

[0010] Preferably, the difunctional (meth)acrylate containing a long carbon chain includes one of 1,11-undecanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate; and the multifunctional (meth)acrylate containing a long carbon chain includes one of trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, propoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

[0011] Furthermore, the benzene ring-containing (meth) acrylic monomer includes: o-phenylphenoxyethyl acrylate (OPPEA) or m-phenoxybenzyl acrylate (MPOBA); wherein the chemical structure of OPPEA is as follows: Formula 1, and the chemical structure of MPOBA is as follows: Formula 2: Formula 1 Formula 2 OPPEA and MPOBA contain two benzene rings (or benzene ring-derived structures) connected by an ethylene or oxygen bridge, forming a "double benzene ring-isolation chain-double bond" structure. The conjugation effect of the double benzene rings is interrupted by the isolating chain (-CH2CH2- or -O-), resulting in extremely weak conjugation between the double bond and the single benzene ring, producing virtually no additional chromophores and enabling controlled yellowness. Furthermore, the PPO backbone is an aromatic polyether (containing a repeating benzene ring structure). The benzene-ring-containing (meth)acrylic monomer of the present invention forms a strong "multi-benzene ring-multi-benzene ring" π-π interaction with the benzene rings of PPO, enhancing the density of the crosslinked network, resulting in a moderate double bond density, consistent UV curing rate, and improved film uniformity.

[0012] Furthermore, the mass ratio of the polyphenylene ether resin to the (meth) acrylic monomer containing a benzene ring is 1:(1-2), With this setup, when the PPO ratio is higher (1:1), the system is dominated by the rigid PPO segments, maintaining a Tg (glass transition temperature) of 180-200°C (close to pure PPO), making it suitable for bonding to rigid substrates. In this case, the flexible segments of the monomer (ethylene or oxygen bridges) serve only as a "diluent" to reduce viscosity and ensure coating uniformity, while the double benzene ring structure maintains low yellowness and high barrier properties. When the ratio of the benzene-containing (meth)acrylic monomer is higher (1:2), the proportion of the flexible segments (ethylene or oxygen bridges) increases, lowering the system Tg and enhancing flexibility.

[0013] The dielectric constant of the UV curing adhesive is between 2.35 and 2.45; the viscosity of the UV curing adhesive is between 10 and 30 cps, and the surface tension is between 27 and 30 mN / m.

[0014] Preferably, the polyphenylene oxide resin (PPO / PPE) is NORYL™ SA9000 resin, XYRON™ SZA2000 or XYRON™ SZA3000.

[0015] On the other hand, the present invention also provides a method for preparing a low-dielectric UV-curing adhesive based on a modified polyphenylene ether resin as described in part or in whole above, wherein the above-mentioned raw materials are added into a reaction vessel according to corresponding parts by weight, and the low-dielectric UV-curing adhesive is obtained after being mixed evenly using a stirrer.

[0016] In addition, the present invention also provides a use of a low-dielectric UV-curable adhesive based on a modified polyphenylene ether resin as described in part or in whole above in a thin film encapsulation process for an OLED device.

[0017] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention introduces the rigid main chain structure of polyphenylene ether resin into the acrylate-based light-curable inkjet printing system by copolymerization or blending, which has the following two advantages: 1) Structural strengthening: PPO segments can partially replace long-chain monofunctional acrylates (such as lauryl acrylate) used to reduce viscosity in traditional formulas. While maintaining low ink viscosity (10-30 cps), it is also necessary to avoid excessive addition of polyphenylene ether resin, which may lead to a decrease in cross-linking network density. The flexible alkyl groups of long-chain monomers will reduce the cross-linking density, while PPO forms physical cross-linking points through π-π stacking of benzene rings to maintain network integrity. Adding 5-10 parts of PPO can significantly improve the tensile strength and Young's modulus of the cured film, while the ether bonds retain toughness and increase the elongation at break.

[0018] In addition, OPPEA in the dispersant has a rigid o-phenyl structure, which has a strong π-π stacking anchoring effect on PPO, and MPOBA has ester polarity, which realizes the effect of hydrogen bonding to enhance interfacial bonding.

[0019] 2) Dielectric Retention: Based on the intrinsic low polarity of PPO materials, when it is introduced into the acrylic low-dielectric TFE-INK material and the addition amount is controlled within the range of this application, the dielectric constant of the system can still remain stable and controlled between 2.35 and 2.45, without significantly increasing, achieving a precise balance of "low viscosity-high modulus-low dielectric", providing an optimized path for high-end electronic packaging. DETAILED DESCRIPTION

[0020] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0021] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is further described in detail below with reference to the embodiments.

[0022] The components and proportions of the UV curing adhesive in the following examples and comparative examples are shown in Table 1: Table 1 Example 1 This embodiment provides a low-dielectric UV-curable adhesive based on modified polyphenylene ether resin, comprising the following components in parts by weight: 10 parts of polyphenylene ether resin, 10 parts of a (meth)acrylic monomer containing a benzene ring, 50 parts of a monofunctional (meth)acrylate containing a long carbon chain, 25 parts of a difunctional (meth)acrylate containing a long carbon chain, and 5 parts of a photocrosslinking initiator.

[0023] The raw material selection and preparation process of this UV-curing adhesive are as follows: the polyphenylene ether resin uses NORYL™ SA9000 resin (number average molecular weight Mn=2300) developed by Saudi Basic Industries Corporation (SABIC), the (meth) acrylic monomer containing a benzene ring uses o-phenylphenoxyethyl acrylate (OPPEA), the monofunctional (meth) acrylate containing a long carbon chain uses lauryl methacrylate, and the difunctional (meth) acrylate containing a long carbon chain uses 1,11-undecanediol diacrylate to increase the crosslinking density of the material after curing. TPO initiator is used as the photocrosslinking initiator. The preparation process is as follows: 10 parts of NORYL™ SA9000 resin and 10 parts of OPPEA are diluted with 50 parts of lauryl methacrylate, and then 25 parts of 1,11-undecanediol diacrylate are added to increase the crosslinking density of the material after curing, and 5 parts of photoinitiator TPO are added. After mixing evenly, a light reddish-brown transparent liquid with a viscosity of 18.56 cps and a surface tension of 28.71 mN / m is obtained. The dielectric constant at 100 kHz is 2.39 as measured by the plate capacitance method. A 30μm film is tested using a dynamic mechanical analysis device, and the tensile strength of the film is 17.92 MPa, the Young's modulus is 0.32 GPa, the elongation at break is 6.99%, and the yellowness (10μm) after curing is 0.64.

[0024] Example 2 This embodiment provides a low-dielectric UV-curable adhesive based on modified polyphenylene ether resin, comprising the following components in parts by weight: 5 parts of polyphenylene ether resin, 10 parts of a (meth)acrylic monomer containing a benzene ring, 55 parts of a monofunctional (meth)acrylate containing a long carbon chain, 25 parts of a difunctional (meth)acrylate containing a long carbon chain, and 5 parts of a photocrosslinking initiator.

[0025] The raw material selection and preparation process of this UV-curing adhesive are as follows: the polyphenylene ether resin uses NORYL™ SA9000 resin (number average molecular weight Mn=2300) developed by Saudi Basic Industries Corporation (SABIC), the (meth) acrylic monomer containing a benzene ring uses o-phenylphenoxyethyl acrylate (OPPEA), the monofunctional (meth) acrylate containing a long carbon chain uses lauryl methacrylate, and the difunctional (meth) acrylate containing a long carbon chain uses 1,11-undecanediol diacrylate to increase the crosslinking density of the material after curing. The photocrosslinking initiator uses photoinitiator 819. The preparation process is as follows: 5 parts of NORYL™ SA9000 resin and 10 parts of OPPEA are diluted with 55 parts of lauryl methacrylate, and then 25 parts of 1,11-undecanediol diacrylate are added to increase the crosslinking density of the material after curing, and 5 parts of photoinitiator 819 are added. After mixing evenly, a light reddish-brown transparent liquid with a viscosity of 16.77 cps and a surface tension of 27.92 mN / m is obtained. The dielectric constant at 100 kHz is 2.37 as measured by the plate capacitance method. A 30μm film is tested using a dynamic mechanical analysis device, and the tensile strength of the film is 12.38 MPa, the Young's modulus is 0.27 GPa, the elongation at break is 7.52%, and the yellowness (10μm) after curing is 0.56.

[0026] Example 3 This embodiment provides a low-dielectric UV-curable adhesive based on modified polyphenylene ether resin, comprising the following components in parts by weight: 5 parts of polyphenylene ether resin, 10 parts of a (meth)acrylic monomer containing a benzene ring, 55 parts of a monofunctional (meth)acrylate containing a long carbon chain, 25 parts of a difunctional (meth)acrylate containing a long carbon chain, and 5 parts of a photocrosslinking initiator.

[0027] The raw material selection and preparation process of this UV-curing adhesive are as follows: the polyphenylene ether resin uses NORYL™ SA9000 resin (number average molecular weight Mn=2300) developed by Saudi Basic Industries Corporation (SABIC), the (meth) acrylic monomer containing a benzene ring uses m-phenoxybenzyl acrylate (MPOBA), the monofunctional (meth) acrylate containing a long carbon chain uses lauryl methacrylate, and the difunctional (meth) acrylate containing a long carbon chain uses 1,11-undecanediol diacrylate to increase the crosslinking density of the material after curing. The photocrosslinking initiator uses TPO photoinitiator. The preparation process is as follows: 5 parts of NORYL™ SA9000 resin and 10 parts of MPOBA are diluted with 55 parts of lauryl methacrylate, and then 25 parts of 1,11-undecanediol diacrylate are added to increase the crosslinking density of the material after curing, and 5 parts of photoinitiator TPO are added. After mixing evenly, a light reddish-brown transparent liquid with a viscosity of 15.59 cps and a surface tension of 29.01 mN / m is obtained. The dielectric constant at 100 kHz is 2.45 as measured by the plate capacitance method. A 30μm film is tested using a dynamic mechanical analysis device, and the tensile strength of the film is 13.12 MPa, the Young's modulus is 0.28 GPa, the elongation at break is 7.29%, and the yellowness (10μm) after curing is 0.57.

[0028] Example 4 This embodiment provides a low-dielectric UV-curable adhesive based on modified polyphenylene ether resin, comprising the following components in parts by weight: 10 parts of polyphenylene ether resin, 10 parts of a (meth)acrylic monomer containing a benzene ring, 50 parts of a monofunctional (meth)acrylate containing a long carbon chain, 25 parts of a difunctional (meth)acrylate containing a long carbon chain, and 5 parts of a photocrosslinking initiator.

[0029] The raw material selection and preparation process of this UV-curing adhesive are as follows: Asahi Kasei XYRON™ SZA2000 is used as the polyphenylene ether resin, o-phenylphenoxyethyl acrylate (OPPEA) is used as the (meth) acrylic monomer containing a benzene ring, lauryl methacrylate is used as the monofunctional (meth) acrylate containing a long carbon chain, and 1,6-hexanediol diacrylate is used as the difunctional (meth) acrylate containing a long carbon chain to increase the crosslinking density of the material after curing. TPO photoinitiator is used as the photocrosslinking initiator. The preparation process is as follows: 10 parts of XYRON™ SZA2000 resin and 10 parts of OPPEA are diluted with 50 parts of lauryl methacrylate, and then 25 parts of 1,6-hexanediol diacrylate are added to increase the crosslinking density of the material after curing, and 5 parts of photoinitiator TPO are added. After mixing evenly, a light reddish-brown transparent liquid with a viscosity of 17.27 cps and a surface tension of 28.68 mN / m is obtained. The dielectric constant at 100 kHz is 2.44 as measured by the plate capacitance method. A 30μm film is tested using a dynamic mechanical analysis device, and the tensile strength of the film is 14.04 MPa, the Young's modulus is 0.28 GPa, the elongation at break is 6.81%, and the yellowness (10μm) after curing is 0.69.

[0030] Example 5 This embodiment provides a low-dielectric UV-curable adhesive based on modified polyphenylene ether resin, comprising the following components in parts by weight: 10 parts of polyphenylene ether resin, 10 parts of a (meth)acrylic monomer containing a benzene ring, 50 parts of a monofunctional (meth)acrylate containing a long carbon chain, 25 parts of a difunctional (meth)acrylate containing a long carbon chain, and 5 parts of a photocrosslinking initiator.

[0031] The raw material selection and preparation process of this UV-curing adhesive are as follows: Asahi Kasei XYRON™ SZA3000 is used as the polyphenylene ether resin, o-phenylphenoxyethyl acrylate (OPPEA) is used as the (meth) acrylic monomer containing a benzene ring, isooctyl methacrylate is used as the monofunctional (meth) acrylate containing a long carbon chain, and trimethylolpropane trimethacrylate is used as the polyfunctional (meth) acrylate containing a long carbon chain to increase the crosslinking density of the material after curing. TPO photoinitiator is used as the photocrosslinking initiator. The preparation process is as follows: 10 parts of XYRON™ SZA3000 resin and 10 parts of OPPEA are diluted with 50 parts of isooctyl methacrylate, and then 25 parts of trimethylolpropane trimethacrylate are added to increase the crosslinking density of the material after curing, and 5 parts of photoinitiator TPO are added. After mixing, a light reddish-brown transparent liquid with a viscosity of 18.01 cps and a surface tension of 28.19 mN / m is obtained. The dielectric constant at 100 kHz is 2.42 as measured by the plate capacitance method. A 30μm film is tested using a dynamic mechanical analysis device, and the tensile strength of the film is 19.97 MPa, the Young's modulus is 0.35 GPa, the elongation at break is 6.2%, and the yellowness (10μm) after curing is 0.71.

[0032] Comparative Example 1 This comparative example provides a UV-curable adhesive without the addition of NORYL™ SA9000 resin and a benzene ring-containing (meth)acrylic monomer. Instead, 70 parts of lauryl methacrylate, 25 parts of 1,11-undecanediol diacrylate to increase the crosslinking density of the material after curing, and 5 parts of a photoinitiator, TPO, are used to obtain a light reddish-brown transparent liquid with a viscosity of 14.81 cps and a surface tension of 27.97 mN / m. The dielectric constant at 100 kHz, as measured by the plate capacitance method, is 2.35. A 30 μm film tested using a dynamic mechanical analysis device shows a tensile strength of 8.91 MPa, a Young's modulus of 0.11 GPa, an elongation at break of 8.19%, and a yellowness index (10 μm) of 0.23 after curing.

[0033] Comparative Example 2 This comparative example provides a UV-curable adhesive without the addition of a benzene-ring-containing (meth)acrylic monomer. Instead, 10 parts of NORYL™ SA9000 resin, 60 parts of lauryl methacrylate, 25 parts of 1,11-undecanediol diacrylate to increase the crosslinking density of the cured material, and 5 parts of a photoinitiator, TPO, were added. The resulting system was severely turbid, and the NORYL™ SA9000 resin could not be dispersed in the ink system.

[0034] Comparative Example 3 This comparative example provides a UV-curable adhesive. NORYL™ SA9000 resin is used in an amount of 10 parts. 2-phenoxyethyl acrylate (PHEA) is used as a benzene ring-containing (meth) acrylic monomer in an amount of 10 parts. 50 parts of lauryl methacrylate are used for dilution. 25 parts of 1,11-undecanediol diacrylate are added to increase the crosslinking density of the material after curing. 5 parts of TPO are also added as a photoinitiator. The system is slightly turbid, and the polyphenylene ether resin is difficult to disperse in the ink system. The chemical structure of PHEA is as follows: Formula 3.

[0035] Comparative Example 4 This comparative example provides a UV-curable adhesive comprising 20 parts of NORYL™ SA9000 resin and 20 parts of OPPEA, which are diluted with 40 parts of lauryl methacrylate, and further added with 15 parts of 1,11-undecanediol diacrylate to increase the crosslinking density of the material after curing, and 5 parts of a photoinitiator, TPO. The result is a light reddish-brown transparent liquid with a viscosity of 20.11 cps and a surface tension of 29.83 mN / m. The dielectric constant at 100 kHz, as measured by a plate capacitance method, is 2.61. A 30 μm film tested using a dynamic mechanical analysis device shows a tensile strength of 24.16 MPa, a Young's modulus of 0.41 GPa, an elongation at break of 4.19%, and a yellowness (10 μm) of 0.88 after curing.

[0036] Comparative Example 5 This comparative example provides a UV-curable adhesive comprising 10 parts of NORYL™ SA9000 resin and 20 parts of OPPEA. The adhesive is diluted with 50 parts of lauryl methacrylate, and 15 parts of 1,11-undecanediol diacrylate are added to increase the crosslinking density of the material after curing. Furthermore, 5 parts of a photoinitiator, TPO, are added to obtain a light reddish-brown transparent liquid having a viscosity of 20.92 cps and a surface tension of 30.12 mN / m. The dielectric constant at 100 kHz, as measured by a plate capacitance method, is 2.69. A 30 μm film tested using a dynamic mechanical analysis device shows a tensile strength of 25.01 MPa, a Young's modulus of 0.42 GPa, an elongation at break of 4.04%, and a yellowness (10 μm) of 0.62 after curing.

[0037] In order to further verify the effectiveness of the technical solution provided by the present invention, the corresponding performance tests were carried out on the UV curing adhesives prepared in Examples 1 to 5 and Comparative Examples 1 to 5: using 70mW / cm 2 The film was cured by UV light and a 10μm thick cured film was obtained for performance testing. The specific test includes the following aspects: (1) Viscosity: The viscosity of the high-refractive precursor liquid was tested using a rotational rheometer (EVO type rotational viscometer). The test was performed at 25°C, using a 20 mm diameter conical rotor, and setting the shear rate to 0.01 s. -1 ~500s -1 , and select 10s -1 The viscosity of the samples under different shear rates was compared, and each sample was tested 5 times, and the final data was averaged.

[0038] (2) Surface tension: The surface tension was tested using a surface tension meter (QBZY-2 surface tension meter). The test was conducted at 25°C. Defoaming and centrifugation were performed before the test. Each sample was tested 5 times, and the final data was averaged.

[0039] (3) Dielectric constant: A precision impedance analyzer (4294A, Agilent Technologies) was used at room temperature, Vdc = 0 V, Vac = 100 mV, and a test frequency range of 40 Hz to 40 MHz. Silver paint or gold spraying was applied to both sides of the heat-cured sample resin to form electrodes. The dielectric constant was calculated using the following formula from the test data: 𝑟 =(𝐶×d)⁄(𝜀0×𝑆), where C 、 d and S are the capacitance, thickness and electrode area of ​​the material respectively; e 0 represents the dielectric constant of vacuum, e 0 = 8.854×10 -12 F / m.

[0040] (4) Tensile strength: Based on GB / T 1040-92 "General test methods for mechanical properties of plastics (tensile)"; test conditions: tensile speed 1 mm / min, at least 5 specimens per group, and the average value of the test results.

[0041] (5) Young's modulus: An extensometer (accuracy ±0.1%) was installed on the universal material testing machine to record stress (σ) and strain (ε) data in real time; Curve analysis: The stress-strain curve was drawn and the initial linear segment (the region where stress and strain are in direct proportion) was taken; Modulus was calculated: Young's modulus E = (Δσ / Δε) (unit: GPa), where Δσ is the stress change in the linear segment and Δε is the corresponding strain change.

[0042] (6) Elongation at break: (Based on GB / T 1040-92 "General test methods for mechanical properties of plastics (tensile)"); Test conditions: Tensile speed 1 mm / min, at least 5 specimens per group, average test results. Specimen size: dumbbell-shaped spline with a gauge length of 50 mm and a thickness of 1 mm.

[0043] (7) Yellowing after curing: Measured using a spectrophotometer or colorimeter, according to the ASTM D1925 formula YI =100×(1.28 X −1.06 Z ) / Y , where X, Y, and Z are the tristimulus values ​​of the sample (obtained directly by the spectrophotometer).

[0044] The corresponding test results are shown in Table 2 below.

[0045] Table 2 As shown in Table 2 above, the UV-curable adhesives in Examples 1-5 have an overall viscosity (10-30 cps) and surface tension (27-30 mN / m) within an appropriate range, making them suitable for inkjet printing. They also have a low dielectric constant, excellent overall mechanical properties, and improved elongation at break. The yellowness after curing is also within a reasonable range (0.56-0.71). In Comparative Example 1, due to the lack of polyphenylene ether resin and dispersant, the viscosity was too low, resulting in poor overall mechanical properties of the UV-curable adhesive. In Comparative Example 2, due to the lack of dispersant, the polyphenylene ether resin could not be dispersed. In Comparative Example 3, due to the addition of an inappropriate dispersant, 2-phenoxyethyl acrylate contains only one benzene ring, which does not match the number of benzene rings in PPO, and the short ethylene chain (-CH2CH2-) leads to weak intermolecular forces, which easily causes phase separation after mixing. This results in poor dispersion of the polyphenylene ether resin, resulting in an uneven adhesive layer, localized stress concentration, and reduced density of the encapsulation layer. In Comparative Example 4, due to the excessive addition of polyphenylene ether resin, more dispersant was required, resulting in an increased dielectric constant of the UV-curable adhesive and a high yellowing value. This reduced device brightness and color shift (yellowishness), affecting the display quality. In Comparative Example 5, due to the excessive addition of dispersant, although the polyphenylene ether resin was effectively dispersed, the dielectric constant was significantly increased. Therefore, the technical solution provided by the present invention, by introducing a (meth) acrylic monomer containing a benzene ring, utilizes the π-π conjugation effect and polarity matching principle to achieve stable dispersion of PPO resin in the acrylic system. Moreover, the weight proportion of PPO resin in the final material is only 5 to 10 parts, which can improve the mechanical properties of the UV-curable adhesive formula and reduce the dielectric constant, thereby overcoming the problem of poor mechanical properties of current low-dielectric UV-curable adhesives.

[0046] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0047] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A low dielectric UV curing adhesive based on modified polyphenylene ether resin, characterized in that: By introducing a (meth) acrylic acid monomer containing a benzene ring and utilizing the π-π conjugation effect and polarity matching principle, the stable dispersion of polyphenylene ether resin in the acrylic acid system is achieved.

2. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 5-10 parts of polyphenylene ether resin, 10-20 parts of benzene ring-containing (meth)acrylic monomer, 45-65 parts of monofunctional (meth)acrylate containing a long carbon chain, 20-30 parts of difunctional / polyfunctional (meth)acrylate containing a long carbon chain, and 1-10 parts of a photocrosslinking initiator.

3. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 2, characterized in that: The monofunctional (meth)acrylate containing a long carbon chain includes one of lauryl methacrylate, isooctyl methacrylate, isononyl acrylate, stearic acid acrylate, and isodecyl acrylate.

4. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 2, characterized in that: The difunctional (meth)acrylate containing a long carbon chain includes one of 1,11-undecanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate; the multifunctional (meth)acrylate containing a long carbon chain includes one of trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, propoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

5. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 1, characterized in that: The (meth) acrylic monomer containing a benzene ring includes one of o-phenylphenoxyethyl acrylate and m-phenoxybenzyl acrylate.

6. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 1, characterized in that: The dielectric constant of the UV curing adhesive is between 2.35 and 2.

45.

7. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 1, characterized in that: The viscosity of the UV curing adhesive is 10-30 cps, and the surface tension is 27-30 mN / m.

8. The low dielectric UV curing adhesive based on modified polyphenylene ether resin according to claim 1, characterized in that: The polyphenylene ether resin is NORYL™ SA9000 resin, XYRON™ SZA2000 or XYRON™ SZA3000.

9. A method for preparing a low-dielectric UV-curable adhesive based on modified polyphenylene ether resin according to any one of claims 2 to 8, characterized in that: The above raw materials are added into a reaction container according to corresponding weight parts, and mixed evenly with a stirrer to obtain a low-dielectric UV-curable adhesive.

10. Use of the low-dielectric UV-curable adhesive based on modified polyphenylene ether resin according to any one of claims 1 to 8 in a thin film encapsulation process for OLED devices.

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