Acrylate prepolymer, antioxidant optical cement, preparation method and application

Abstract

The invention relates to an acrylate prepolymer, an antioxidant optical adhesive and a preparation method and application thereof. The acrylate prepolymer is prepared from the following raw materials in parts by weight: 5-80 parts of a soft monomer; 5-30 parts by weight of a hard monomer; 5-20 parts by weight of a hydroxyl crosslinking monomer; 1-20 parts by weight of an antioxidant; and 0.05 to 1 part by weight of a first photoinitiator. The acrylate prepolymer and the optical cement can inhibit the oxidation phenomenon of a nano-silver conductive film circuit under high temperature and high humidity, improve the stability of the nano-silver conductive film in the manufacturing process of electronic devices, and reduce the impedance change rate of the nano-silver conductive film.

Description

Technical Field

[0001] The present invention relates to the field of OCA optical adhesives, and specifically relates to acrylate prepolymers, antioxidant optical adhesives, and preparation methods and applications thereof. Background Art

[0002] In the optoelectronic industry, touch display screens as the human-computer interaction window are a major research hotspot. In recent years, with the development of intelligent electronic products, touch screens with advantages such as fast response and easy operation have become the mainstream in the market. Such optical devices as touch screens contain multiple layers of components inside, and their overall optical effect, sensitivity, and reliability need to be ensured during long-term use. Therefore, these components need to be filled and bonded. Optical adhesives (OCA) have advantages such as high light transmittance, low haze, and high temperature resistance, and are commonly used for bonding electronic devices such as touch screens, playing roles such as filling and improving screen brightness. Although optical adhesives usually have a small usage amount and low cost when bonding electronic devices, their properties affect consumers' usage experience of electronic products.

[0003] The synthesis raw materials of acrylate optical adhesives are widely sourced and have excellent optical properties, and they are one of the most widely used adhesive systems at present. However, traditional acrylate optical adhesives have problems such as insufficient filling property, reliability, and lack of antioxidant components, which have an adverse impact on some sensitive electronic devices in practical applications. Usually, when an optical adhesive bonds an electronic device such as a touch screen, it needs to directly contact a conductive material. If the acid value of the optical adhesive is high, the two will react, resulting in a decrease in the sensitivity of the electronic device or even inability to work. In addition, some conductive materials such as nano silver have high reactivity and are sensitive to air. If the bonding and encapsulation effect of the optical adhesive is poor, the conductivity of nano silver will be affected. These problems limit the application development of optical adhesives for bonding nano silver conductive films. Therefore, it is necessary to develop an antioxidant optical adhesive for bonding nano silver conductive films. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the first object of the present invention is to provide an acrylate prepolymer with good antioxidant performance.

[0005] The second object of the present invention is to provide a preparation method of the acrylate prepolymer.

[0006] The third object of the present invention is to provide an antioxidant optical adhesive containing the acrylate prepolymer, which has good antioxidant performance and can resist the erosion of oxygen and water vapor in a high-temperature and high-humidity environment.

[0007] The fourth object of the present invention is to provide a preparation method of the antioxidant optical adhesive.

[0008] The fifth object of the present invention is to provide an application of the antioxidant optical adhesive, which can reduce the impedance change rate of the nano-silver conductive film and play a good protective role.

[0009] To achieve the first object of the present invention, the present invention provides an acrylate prepolymer, which is prepared from raw materials comprising the following components in parts by weight: 5-80 parts by weight of a soft monomer; 5-30 parts by weight of a hard monomer; 5-20 parts by weight of a hydroxyl crosslinking monomer; 1-20 parts by weight of an antioxidant; 0.05-1 part by weight of a first photoinitiator; wherein, the glass transition temperature of the soft monomer is less than 0 °C, and the glass transition temperature of the hard monomer is greater than 25 °C.

[0010] In some embodiments of the present invention, the soft monomer includes at least two of 2-ethylhexyl acrylate (2-EHA), isodecyl acrylate (IDA), isodecyl methacrylate (IDMA), ethoxyethoxyethyl acrylate (EOEOEA), lauryl acrylate (LA), lauryl methacrylate (LMA), tetrahydrofurfuryl acrylate (THFA), and caprolactone acrylate (CA).

[0011] In some embodiments of the present invention, the hard monomer includes at least one of isobornyl methacrylate (IBOMA), isobornyl acrylate (IBOA), methyl methacrylate (MMA), ethyl methacrylate (EMA), isopropyl methacrylate (IPMA), isobutyl methacrylate (IBMA), acrylonitrile (AN), and styrene (St).

[0012] In some embodiments of the present invention, the hydroxyl crosslinking monomer includes at least two of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl acrylate (HPA), 2-hydroxypropyl methacrylate (HPMA), and 4-hydroxybutyl acrylate (HBA).

[0013] In some embodiments of the present invention, the antioxidant includes at least one of acrylamide (AM), diacetone acrylamide (DAAM), 4-acryloylmorpholine (ACMO), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,6-di-tert-butyl-p-ethylphenol, 2,4,6-tri-tert-butylphenol, N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0014] In some embodiments of the present invention, the first photoinitiator includes at least one of (2,4,6-trimethylbenzoyl) bis (p-tolyl) phosphine oxide (TMO), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoyl phenylphosphinate (TPO-L), hydroxycyclohexyl phenyl ketone (184), benzophenone (BP), 2,2-dimethoxy-2-phenylacetophenone (651), 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone (907).

[0015] In some embodiments of the present invention, the soft monomer is a mixture of 2-ethylhexyl acrylate (2-EHA) and tetrahydrofurfuryl acrylate (THFA), and the weight ratio of 2-ethylhexyl acrylate (2-EHA) to tetrahydrofurfuryl acrylate (THFA) is (57-61):10.

[0016] In some embodiments of the present invention, the hydroxy crosslinking monomer is a mixture of 2-hydroxyethyl acrylate (HEA) and 2-hydroxyethyl methacrylate (HEMA), and the mass ratio of 2-hydroxyethyl acrylate (HEA) to 2-hydroxyethyl methacrylate (HEMA) is (8-12):3.

[0017] In some embodiments of the present invention, the mass parts of each component in the raw materials of the acrylate prepolymer are as follows: 67-71 parts by weight of the soft monomer; 12-14 parts by weight of the hard monomer; 11-15 parts by weight of the hydroxy crosslinking monomer; 3-8 parts by weight of the antioxidant; 0.05-0.2 parts by weight of the first photoinitiator; further, the mass parts of each component are as follows: 69-71 parts by weight of the soft monomer; 13 parts by weight of the hard monomer; 11-13 parts by weight of the hydroxy crosslinking monomer; 4-6 parts by weight of the antioxidant; 0.05-0.2 parts by weight of the first photoinitiator.

[0018] To achieve the second object of the present invention, the present invention provides a preparation method of an acrylate prepolymer according to any one of the above solutions, which includes the following steps: adding the soft monomer, the hard monomer, the hydroxy crosslinking monomer, the antioxidant and the first photoinitiator into a reaction kettle, introducing nitrogen and stirring, and then turning on an ultraviolet lamp to carry out a polymerization reaction to obtain an acrylate prepolymer.

[0019] In some embodiments of the present invention, the stirring time is 15-25 minutes.

[0020] In some embodiments of the present invention, the polymerization reaction stops when the temperature rises by 16°C.

[0021] To achieve the third object of the present invention, the present invention provides an antioxidant optical adhesive, which is prepared from raw materials comprising the following components in parts by weight: 100 to 101 parts by weight of an acrylate prepolymer; 0.05 to 2 parts by weight of a crosslinking agent; 0.05 to 2 parts by weight of a silane coupling agent; 0.02 to 1 part by weight of a second photoinitiator; wherein, the acrylate prepolymer is one of the acrylate prepolymers described in any of the above solutions or the acrylate prepolymer obtained by the preparation method of any of the above solutions; the parts by weight of the acrylate prepolymer are calculated based on the solid of the acrylate prepolymer.

[0022] In some embodiments of the present invention, the crosslinking agent includes at least one of 1,6 - hexanediol diacrylate (HDDA), 1,4 - butanediol diacrylate (BDDA), trimethylolpropane triacrylate (TMPTA), 1,4 - butanediol dimethacrylate (BDDMA), dipropylene glycol diacrylate (DPGDA), diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), pentaerythritol triacrylate (PETA), 2(trimethylolpropane) tetraacrylate (DTMPTTA).

[0023] In some embodiments of the present invention, the silane coupling agent includes at least one of γ - glycidoxypropyltrimethoxysilane (KH560), γ - aminopropyltriethoxysilane (KH550), γ - methacryloxypropyltrimethoxysilane (KH570), vinyltris(β - methoxyethoxy)silane.

[0024] In some embodiments of the present invention, the second photoinitiator includes at least one of (2,4,6 - trimethylbenzoyl)bis(p - tolyl)phosphine oxide (TMO), 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide (TPO), ethyl 2,4,6 - trimethylbenzoyl - phenylphosphinate (TPO - L), hydroxycyclohexyl phenyl ketone (184), benzophenone (BP).

[0025] In some embodiments of the present invention, the mass parts of each component in the raw materials of the antioxidant optical adhesive are: 100 to 100.2 parts by weight of an acrylate prepolymer; 0.05 to 0.2 parts by weight of a crosslinking agent; 0.1 to 0.3 parts by weight of a silane coupling agent; 0.02 to 0.1 parts by weight of a second photoinitiator.

[0026] To achieve the fourth object of the present invention, the present invention provides a preparation method of the antioxidant optical adhesive described in any of the above solutions, which includes the following steps: adding the crosslinking agent, the silane coupling agent and the second photoinitiator to the acrylate prepolymer, fully stirring and then defoaming under vacuum, and then using a coater to coat on a release film and a substrate, and putting it into an ultraviolet lamp box for curing.

[0027] In some embodiments of the present invention, the thickness of the release film is 50 - 100 μm.

[0028] In some embodiments of the present invention, the substrate is PET.

[0029] In some embodiments of the present invention, the thickness of the substrate is 50 - 100 μm.

[0030] In some embodiments of the present invention, the curing time is 5 - 8 min.

[0031] In some embodiments of the present invention, the total light energy of the ultraviolet lamp box is 1300 - 1600 mJ / cm 2 。

[0032] In some embodiments of the present invention, the thickness of the cured adhesive film is 100 - 150 μm.

[0033] To achieve the fifth object of the present invention, the present invention provides an application of an antioxidant optical adhesive in an electronic device. The electronic device includes a nano - silver conductive film, and the antioxidant optical adhesive is adhered to the nano - silver conductive film; the antioxidant optical adhesive is an antioxidant optical adhesive according to any of the above - mentioned solutions, or an antioxidant optical adhesive obtained by the preparation method according to any of the above - mentioned solutions.

[0034] Compared with the prior art, the present invention can achieve the following effective effects:

[0035] The acrylate prepolymer of the present invention and the antioxidant optical adhesive containing the acrylate prepolymer have good antioxidant performance, do not contain components such as sulfides that are likely to corrode the nano - silver conductive film, have good compatibility with the nano - silver conductive film, and can resist the erosion of oxygen and water vapor in a high - temperature and high - humidity environment after being adhered to the nano - silver conductive film, reducing its impedance change rate, thereby playing a good protective role in the manufacturing process of electronic devices. At the same time, the hydroxyl cross - linking monomer, which is one of the components of the optical adhesive, can interact with water molecules in a high - temperature and high - humidity environment, so that the optical adhesive maintains good bonding effect in a high - temperature and high - humidity environment and will not show peeling phenomenon due to water molecule penetration. Secondly, by reasonably matching the proportions of the soft monomer, hard monomer, hydroxyl cross - linking monomer and antioxidant, the optical adhesive prepared by the present invention has good bonding effect and optical properties, and is suitable for large - size electronic devices such as nano - silver conductive films. Detailed embodiments

[0036] Embodiments of the present invention provide an acrylate prepolymer, an antioxidant optical adhesive, a preparation method and an application. By introducing an antioxidant component into the acrylate prepolymer and the antioxidant optical adhesive, the oxidation phenomenon of the nano-silver conductive film circuit under high temperature and high humidity can be inhibited, the stability of the nano-silver conductive film in the manufacturing process of electronic devices can be improved, and its impedance change rate can be reduced. The acrylate prepolymer and the antioxidant optical adhesive of this embodiment are suitable for protecting the nano-silver conductive film and other electronic devices. Of course, the acrylate prepolymer and the antioxidant optical adhesive of this embodiment can also be applied to other fields.

[0037] Specifically, the acrylate prepolymer of this embodiment is prepared from raw materials containing the following components in parts by weight: 5-80 parts by weight of a soft monomer; 5-30 parts by weight of a hard monomer; 5-20 parts by weight of a hydroxyl crosslinking monomer; 1-20 parts by weight of an antioxidant; 0.05-1 part by weight of a first photoinitiator.

[0038] Among them, the glass transition temperature of the soft monomer is less than 0 °C, and the glass transition temperature of the hard monomer is greater than 25 °C. In this embodiment, by reasonably matching the proportions of the soft monomer, hard monomer, hydroxyl crosslinking monomer and antioxidant, the acrylate prepolymer has appropriate polar groups and antioxidant components. The hydroxyl crosslinking monomer can interact with water molecules in a high temperature and high humidity environment, so that the optical adhesive can maintain good adhesion in a high temperature and high humidity environment and will not peel off due to water molecule penetration. Therefore, the obtained prepolymer can maintain good adhesion in a high temperature and high humidity environment, can reduce the impedance change rate of the nano-silver conductive film, and inhibit its oxidation phenomenon in a high temperature and high humidity environment. In addition, the prepolymer also has good optical properties.

[0039] In some examples, the raw materials of the acrylate prepolymer mainly consist of the following components in parts by weight: 5-80 parts by weight of a soft monomer; 5-30 parts by weight of a hard monomer; 5-20 parts by weight of a hydroxyl crosslinking monomer; 1-20 parts by weight of an antioxidant; 0.05-1 part by weight of a first photoinitiator. In addition to the above raw materials, the raw materials of the acrylate prepolymer may also contain other additives.

[0040] In some examples, the raw materials of the acrylate prepolymer consist of the following components in parts by weight: 5-80 parts by weight of a soft monomer; 5-30 parts by weight of a hard monomer; 5-20 parts by weight of a hydroxyl crosslinking monomer; 1-20 parts by weight of an antioxidant; 0.05-1 part by weight of a first photoinitiator. Except for the above raw materials and necessary impurities, the raw materials of the acrylate prepolymer do not contain other substances, and the composition is simpler.

[0041] In some examples, the total mass parts of the soft monomer, hard monomer, hydroxyl crosslinking monomer and antioxidant in the raw materials of the acrylate prepolymer are 100 mass parts, which is convenient for the proportioning and weighing of each component of the raw materials.

[0042] In some examples, the soft monomers include at least two of 2-ethylhexyl acrylate (2-EHA), isodecyl acrylate (IDA), isodecyl methacrylate (IDMA), ethoxyethoxyethyl acrylate (EOEOEA), lauryl acrylate (LA), lauryl methacrylate (LMA), tetrahydrofurfuryl acrylate (THFA), and caprolactone acrylate (CA). The above soft monomers contain flexible hydrocarbon groups or ether groups. By mixing at least two soft monomers, a polymer with a suitable modulus is obtained.

[0043] In some examples, the hard monomers include at least one of isobornyl methacrylate (IBOMA), isobornyl acrylate (IBOA), methyl methacrylate (MMA), ethyl methacrylate (EMA), isopropyl methacrylate (IPMA), isobutyl methacrylate (IBMA), acrylonitrile (AN), and styrene (St). The above hard monomers contain relatively rigid polar groups, rings, or methyl groups. By combining the soft monomers and the hard monomers, the mechanical properties of the prepolymer can be adjusted.

[0044] In some examples, the hydroxyl crosslinking monomers include at least two of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl acrylate (HPA), 2-hydroxypropyl methacrylate (HPMA), and 4-hydroxybutyl acrylate (HBA). By mixing at least two hydroxyl crosslinking monomers, the adhesion effect of the adhesive can be improved.

[0045] In some examples, the antioxidants include at least one of acrylamide (AM), diacetone acrylamide (DAAM), 4-acryloylmorpholine (ACMO), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,6-di-tert-butyl-p-ethylphenol, 2,4,6-tri-tert-butylphenol, N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. The above antioxidants can effectively improve the antioxidant performance of the adhesive and are resistant to high-temperature and high-humidity environments.

[0046] In some examples, the first photoinitiators include at least one of (2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide (TMO), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoyl phenylphosphinate (TPO-L), hydroxycyclohexyl phenyl ketone (184), benzophenone (BP), 2,2-dimethoxy-2-phenylacetophenone (651), and 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone (907). The above photoinitiators can effectively initiate the polymerization of monomers to form prepolymers.

[0047] In some examples, the soft monomer is a mixture of 2-ethylhexyl acrylate (2-EHA) and tetrahydrofurfuryl acrylate (THFA), and the weight ratio of 2-ethylhexyl acrylate (2-EHA) to tetrahydrofurfuryl acrylate (THFA) is (57-61):10. When the soft monomer adopts the above monomer types and ratio, the resulting acrylate prepolymer has a suitable modulus.

[0048] In some examples, the hydroxyl crosslinking monomer is a mixture of 2-hydroxyethyl acrylate (HEA) and 2-hydroxyethyl methacrylate (HEMA), and the mass ratio of 2-hydroxyethyl acrylate (HEA) to 2-hydroxyethyl methacrylate (HEMA) is (8-12):3. When the hydroxyl crosslinking monomer adopts the above monomer types and ratio, the resulting acrylate prepolymer has better antioxidant properties.

[0049] In some examples, the mass parts of each component in the raw materials of the acrylate prepolymer are as follows: 67-71 parts by weight of the soft monomer; 12-14 parts by weight of the hard monomer; 11-15 parts by weight of the hydroxyl crosslinking monomer; 3-8 parts by weight of the antioxidant; 0.05-0.2 parts by weight of the first photoinitiator. For example, in parts by weight, the soft monomer can be 67 parts, 68 parts, 69 parts, 70 parts or 71 parts; the hard monomer can be 12 parts, 13 parts or 14 parts; the hydroxyl crosslinking monomer can be 11 parts, 12 parts, 13 parts, 14 parts or 15 parts; the antioxidant can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts; the first photoinitiator can be 0.05 parts, 0.1 parts, 0.15 parts or 0.2 parts. When the mass parts of each component in the raw materials of the acrylate prepolymer are within the above ranges, the resulting acrylate prepolymer has better antioxidant properties.

[0050] Furthermore, the mass parts of each component are as follows: 69-71 parts by weight of the soft monomer; 13 parts by weight of the hard monomer; 11-13 parts by weight of the hydroxyl crosslinking monomer; 4-6 parts by weight of the antioxidant; 0.05-0.2 parts by weight of the first photoinitiator. When the mass parts of each component in the raw materials of the acrylate prepolymer are within the above ranges, the antioxidant properties of the resulting acrylate prepolymer are further improved.

[0051] In some examples, the preparation method of the above acrylate prepolymer includes the following steps: adding the soft monomer, hard monomer, hydroxyl crosslinking monomer, antioxidant and first photoinitiator into a reaction kettle, introducing nitrogen and stirring, and then turning on an ultraviolet lamp to carry out a polymerization reaction to obtain the acrylate prepolymer. The above preparation method has simple steps and controllable reaction degree, and can avoid the oxidation of the acrylate prepolymer.

[0052] In some examples, the stirring time is 15-25 minutes to make the raw materials disperse evenly.

[0053] In some examples, the polymerization reaction stops when the temperature rises by 16 °C, which is convenient for controlling the degree of polymerization of the prepolymer and beneficial to controlling the viscosity, crosslinking degree, and processing performance of the adhesive.

[0054] In some examples, this embodiment also provides an antioxidant optical adhesive, which is prepared from raw materials containing the following components in parts by weight: 100 - 101 parts by weight of the acrylate prepolymer of any of the above examples; 0.05 - 2 parts by weight of a crosslinking agent; 0.05 - 2 parts by weight of a silane coupling agent; 0.02 - 1 part by weight of a second photoinitiator. Among them, the parts by weight of the acrylate prepolymer are calculated based on the solid of the acrylate prepolymer.

[0055] It can be seen that the antioxidant optical adhesive of this embodiment further adds a crosslinking agent, a silane coupling agent, and a second photoinitiator to the acrylate prepolymer, endowing the acrylate prepolymer with a higher crosslinking degree and adhesion. The antioxidant optical adhesive of this embodiment has good antioxidant performance, does not contain components such as sulfides that are likely to corrode the nano - silver conductive film, has good compatibility with the nano - silver conductive film, and can protect the nano - silver conductive film from the erosion of oxygen and water vapor in a high - temperature and high - humidity environment after being adhered to it, reducing its impedance change rate, thus playing a good protective role in the manufacturing process of electronic devices. The hydroxyl crosslinking monomer in the prepolymer can interact with water molecules in a high - temperature and high - humidity environment, so that the optical adhesive can maintain good bonding effect in a high - temperature and high - humidity environment and will not show peeling phenomenon due to water molecule penetration. By reasonably matching the proportions of soft monomers, hard monomers, hydroxyl crosslinking monomers, and antioxidants, the prepolymer improves the bonding effect and optical properties of the optical adhesive and is suitable for large - size electronic devices such as nano - silver conductive films.

[0056] In some examples, by weight, the acrylate prepolymer can be 100 parts, 100.1 parts, 100.2 parts, 100.3 parts, 100.4 parts, 100.5 parts, 100.6 parts, 100.7 parts, 100.8 parts, 100.9 parts, or 101 parts; the crosslinking agent can be 0.05 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, or 2 parts; the silane coupling agent can be 0.05 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, or 2 parts; the second photoinitiator can be 0.02 parts, 0.05 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1 part.

[0057] In some examples, the raw materials of the antioxidant optical adhesive mainly consist of the following components in parts by weight: 100 - 101 parts by weight of acrylate prepolymer; 0.05 - 2 parts by weight of crosslinking agent; 0.05 - 2 parts by weight of silane coupling agent; 0.02 - 1 part by weight of second photoinitiator. In addition to the above components, the antioxidant optical adhesive of this embodiment may also contain other additives.

[0058] In some examples, the raw materials of the antioxidant optical adhesive consist of the following components in parts by weight: 100 - 101 parts by weight of acrylate prepolymer; 0.05 - 2 parts by weight of crosslinking agent; 0.05 - 2 parts by weight of silane coupling agent; 0.02 - 1 part by weight of second photoinitiator. In addition to the above components, the antioxidant optical adhesive of this embodiment may also contain other additives. Except for the above components and necessary impurities, the antioxidant optical adhesive of this embodiment does not contain other additives.

[0059] In some examples, the crosslinking agent includes at least one of 1,6 - hexanediol diacrylate (HDDA), 1,4 - butanediol diacrylate (BDDA), trimethylolpropane triacrylate (TMPTA), 1,4 - butanediol dimethacrylate (BDDMA), dipropylene glycol diacrylate (DPGDA), diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), pentaerythritol triacrylate (PETA), 2(trimethylolpropane) tetraacrylate (DTMPTTA). The above crosslinking agent contains at least two alkenyl groups and can improve the crosslinking degree of the adhesive.

[0060] In some examples, the silane coupling agent includes at least one of γ - glycidoxypropyltrimethoxysilane (KH560), γ - aminopropyltriethoxysilane (KH550), γ - methacryloxypropyltrimethoxysilane (KH570), vinyltris(β - methoxyethoxy)silane. The above silane coupling agent has easily available raw materials.

[0061] In some examples, the second photoinitiator includes at least one of (2,4,6 - trimethylbenzoyl)bis(p - tolyl)phosphine oxide (TMO), 2,4,6 - trimethylbenzoyl - diphenylphosphine oxide (TPO), ethyl 2,4,6 - trimethylbenzoyl phenylphosphinate (TPO - L), hydroxycyclohexanone (184), benzophenone (BP). The above photoinitiator can initiate the crosslinking reaction of the prepolymer and the crosslinking agent.

[0062] In some examples, the mass parts of each component in the raw materials of the antioxidant optical adhesive are as follows: 100-100.2 parts by weight of acrylate prepolymer; 0.05-0.2 parts by weight of crosslinking agent; 0.1-0.3 parts by weight of silane coupling agent; 0.02-0.1 parts by weight of the second photoinitiator. When the dosage of each component is within the above range, the obtained adhesive has better antioxidant performance.

[0063] In some examples, the preparation method of the above antioxidant optical adhesive includes the following steps: adding a crosslinking agent, a silane coupling agent and a second photoinitiator to the acrylate prepolymer, fully stirring and then defoaming under vacuum, and then using a coater to coat on a release film and a substrate, and putting it into an ultraviolet light box for curing. This preparation method has simple steps, controllable crosslinking reaction, and can be produced on a large scale. Coating on the release film and the substrate using a coater can be to coat the raw materials of the antioxidant optical adhesive on the substrate, and then cover the release film on the raw materials, so that the antioxidant optical adhesive is sandwiched between the release film and the substrate, which is convenient for the application of the antioxidant optical adhesive.

[0064] In some examples, the thickness of the release film is 50-100 μm, and the release film can provide protection for the antioxidant optical adhesive.

[0065] In some examples, the substrate is PET. The raw materials of PET are easily available and have good transparency, which is beneficial to subsequent ultraviolet curing.

[0066] In some examples, the thickness of the substrate is 50-100 μm, and the substrate can provide support for the antioxidant optical adhesive.

[0067] In some examples, the curing time is 5-8 min, so that the antioxidant optical adhesive is moderately crosslinked.

[0068] In some examples, the total light energy of the ultraviolet light box is 1300-1600 mJ / cm 2 , so that the antioxidant optical adhesive is moderately crosslinked.

[0069] In some examples, the thickness of the cured adhesive film is 100-150 μm, which meets the application requirements.

[0070] In some examples, this embodiment also provides the application of the above antioxidant optical adhesive in electronic devices. The electronic device includes a nano silver conductive film. The antioxidant optical adhesive is adhered to the nano silver conductive film, thereby playing a role in protecting the nano silver conductive film. The optical adhesive itself has good antioxidant performance and good compatibility with the nano silver conductive film. After being adhered to the nano silver conductive film, it can resist the erosion of oxygen and water vapor in a high-temperature and high-humidity environment, reduce its impedance change rate, and thus play a good protective role in the manufacturing process of electronic devices.

[0071] The present invention will be further described in detail through specific embodiments below. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0072] Example 1

[0073] Accurately weigh the proportional amounts of soft monomers, hard monomers, hydroxyl crosslinking monomers, antioxidants, and the first photoinitiator and add them to a reaction kettle. After introducing nitrogen and stirring for 20 minutes, turn on the ultraviolet lamp for polymerization reaction. Stop the reaction when the temperature rises by 16°C to obtain a prepolymer. Take the prepared prepolymer, add a crosslinking agent, a photoinitiator, and a silane coupling agent, stir well and defoam under vacuum, and then use a coater to coat it on a 75-μm release film and a 75-μm PET substrate, and place it in an ultraviolet lamp box for curing for 6 minutes. The total light energy is 1500 mJ / cm 2 , and the thickness of the cured adhesive film is 125 μm.

[0074] Examples 2-3 and Comparative Examples 1-3 are carried out with reference to Example 1, and the preparation method is the same as that of Example 1, but the components and their ratios are different, as shown in Table 1 specifically.

[0075] Table 1 Component ratios and dosages of various substances in examples and comparative examples (unit: parts by mass)

[0076]

[0077]

[0078] Test item

[0079] Peel force test: Cut the test sample into strips 25 mm wide, attach them to a glass plate, and then refer to ASTM D3330 "Test Standard for Peel Strength of Pressure-Sensitive Tapes" for testing. Test 5 groups of data and calculate the average value, expressed in gf / 25 mm.

[0080] Impedance change rate test: Cut the nano-silver conductive film into strips 75 mm wide and 250 mm long, coat silver paste at both ends and dry. Bond the optical adhesive to the dried strip, measure its initial resistance, denoted as Z0. Put the strip into an aging test chamber at a temperature of 85°C and a humidity of 85%, take out the sample at 24 h / 240 h / 500 h respectively, let it stand and then measure the impedance Z1 of the sample, and calculate the impedance change rate. Test 5 groups of data and calculate the average value. Impedance change rate = (Z1 - Z0) / Z0 × 100.

[0081] Aging resistance performance test: The prepared sample was laminated with the nano-silver conductive film. After vacuum degassing for 30 min and standing for 24 h, it was then placed in an aging test chamber for high-temperature and high-humidity tests. The high-temperature and high-humidity test was to place the sample for 500 h under the conditions of a temperature of 85 °C and a humidity of 85%, and observe whether bubbles were generated.

[0082] The performance test results of each example and comparative example are shown in Table 2.

[0083] Table 2 Performance test results of each example and comparative example

[0084]

[0085]

[0086] From the optical adhesive test results of Examples 1 to 3 and Comparative Examples 1 to 3, it can be seen that the optical adhesives of Examples 1 to 3 of the present invention have good optical properties and bonding properties. After laminating them with the nano-silver conductive film and placing them in a high-temperature and high-humidity environment, they can maintain good bonding effects without bubble rebound, indicating that an appropriate amount of hydroxyl cross-linking monomer can prevent the optical adhesive from peeling due to water molecule penetration in a high-temperature and high-humidity environment. When the addition amount of the hydroxyl cross-linking monomer is too high, the hydrophilicity of the optical adhesive will be too high, it is easy to absorb water and swell, and the oxidation process of the nano-silver conductive film will be accelerated after bubble rebound, specifically manifested as a significant increase in the impedance change rate.

[0087] In summary, the optical adhesive prepared by the present invention, based on an appropriate amount of polar groups and antioxidant components, has good adhesion to the nano-silver conductive film, can also reduce the impedance change rate of the nano-silver conductive film, and inhibit its oxidation phenomenon in a high-temperature and high-humidity environment.

[0088] Finally, it should be emphasized that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An acrylate prepolymer, characterized in that Prepared from raw materials containing the following components by weight: 5 - 80 parts by weight of soft monomer; 5 - 30 parts by weight of hard monomer; 5 - 20 parts by weight of hydroxyl crosslinking monomer; 1 - 20 parts by weight of antioxidant; 0.05 - 1 part by weight of the first photoinitiator; Among them, the glass transition temperature of the soft monomer is less than 0 °C, and the glass transition temperature of the hard monomer is greater than 25 °C.

2. An acrylate prepolymer according to claim 1, wherein: The soft monomer includes at least two of 2-ethylhexyl acrylate (2-EHA), isodecyl acrylate (IDA), isodecyl methacrylate (IDMA), ethoxyethoxyethyl acrylate (EOEOEA), lauryl acrylate (LA), lauryl methacrylate (LMA), tetrahydrofurfuryl acrylate (THFA), and caprolactone acrylate (CA); And / or, the hard monomer includes at least one of isobornyl methacrylate (IBOMA), isobornyl acrylate (IBOA), methyl methacrylate (MMA), ethyl methacrylate (EMA), isopropyl methacrylate (IPMA), isobutyl methacrylate (IBMA), acrylonitrile (AN), and styrene (St); And / or, the hydroxyl crosslinking monomer includes at least two of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl acrylate (HPA), 2-hydroxypropyl methacrylate (HPMA), and 4-hydroxybutyl acrylate (HBA); And / or, the antioxidant includes at least one of acrylamide (AM), diacetone acrylamide (DAAM), 4-acryloylmorpholine (ACMO), 1,3,5–trimethyl–2,4,6–tris(3,5–di-tert-butyl–4–hydroxybenzyl)benzene, 2,6-di-tert-butyl-p-ethylphenol, 2,4,6-tri-tert-butylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine; And / or, the first photoinitiator includes at least one of (2,4,6-trimethylbenzoyl)di(p-tolyl)phosphine oxide (TMO), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoyl phenylphosphinate (TPO-L), hydroxycyclohexyl phenyl ketone (184), benzophenone (BP), 2,2-dimethoxy-2-phenylacetophenone (651), and 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone (907).

3. An acrylate prepolymer according to claim 2, wherein: The soft monomer is a mixture of 2-ethylhexyl acrylate (2-EHA) and tetrahydrofurfuryl acrylate (THFA), and the weight ratio of 2-ethylhexyl acrylate (2-EHA) to tetrahydrofurfuryl acrylate (THFA) is (57 - 61):10; And / or, the hydroxyl crosslinking monomer is a mixture of 2-hydroxyethyl acrylate (HEA) and 2-hydroxyethyl methacrylate (HEMA), and the mass ratio of 2-hydroxyethyl acrylate (HEA) to 2-hydroxyethyl methacrylate (HEMA) is (8-12):3; And / or, the mass parts of each component in the raw materials of the acrylate prepolymer are: 67-71 parts by weight of soft monomer; 12-14 parts by weight of hard monomer; 11-15 parts by weight of hydroxyl crosslinking monomer; 3-8 parts by weight of antioxidant; 0.05-0.2 parts by weight of the first photoinitiator; Further, the mass parts of each component are: 69-71 parts by weight of soft monomer; 13 parts by weight of hard monomer; 11-13 parts by weight of hydroxyl crosslinking monomer; 4-6 parts by weight of antioxidant; 0.05-0.2 parts by weight of the first photoinitiator.

4. A method for preparing an acrylate prepolymer according to any one of claims 1 to 3, characterized in that Comprising the following steps: Adding the soft monomer, the hard monomer, the hydroxyl crosslinking monomer, the antioxidant and the first photoinitiator into a reaction kettle, introducing nitrogen and stirring, and then turning on an ultraviolet lamp to carry out a polymerization reaction to obtain an acrylate prepolymer.

5. The preparation method according to claim 4, wherein: The stirring time is 15-25 minutes; The polymerization reaction stops when the temperature rises by 16 °C.

6. An antioxidant optical adhesive, characterized in that Prepared from raw materials containing the following components in parts by weight: 100-101 parts by weight of acrylate prepolymer; 0.05-2 parts by weight of crosslinking agent; 0.05-2 parts by weight of silane coupling agent; 0.02-1 parts by weight of the second photoinitiator; Wherein, the acrylate prepolymer is one of the acrylate prepolymers described in any one of claims 1 to 3 or the acrylate prepolymer obtained by the preparation method described in claim 4 or 5; the parts by weight of the acrylate prepolymer are calculated based on the solid of the acrylate prepolymer.

7. The antioxidant optical adhesive according to claim 6, wherein: The crosslinking agent includes at least one of 1,6-hexanediol diacrylate (HDDA), 1,4-butanediol diacrylate (BDDA), trimethylolpropane triacrylate (TMPTA), 1,4-butanediol dimethacrylate (BDDMA), dipropylene glycol diacrylate (DPGDA), diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), pentaerythritol triacrylate (PETA), 2(trimethylolpropane) tetraacrylate (DTMPTTA); And / or, the silane coupling agent includes at least one of γ-glycidoxypropyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH550), γ-methacryloxypropyltrimethoxysilane (KH570), vinyltris(β-methoxyethoxy)silane; And / or, the second photoinitiator includes at least one of (2,4,6-trimethylbenzoyl) bis (p-tolyl) phosphine oxide (TMO), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoyl phenylphosphinate (TPO-L), hydroxycyclohexyl phenyl ketone (184), benzophenone (BP); And / or, the mass parts of each component in the raw materials of the antioxidant optical adhesive are: 100-100.2 parts by weight of acrylate prepolymer; 0.05-0.2 parts by weight of crosslinking agent; 0.1-0.3 parts by weight of silane coupling agent; 0.02-0.1 parts by weight of second photoinitiator.

8. The preparation method of an antioxidant optical adhesive according to claim 6 or 7, characterized in that Comprising the following steps: Adding the crosslinking agent, the silane coupling agent and the second photoinitiator into the acrylate prepolymer, fully stirring and then defoaming under vacuum, and then coating with a coater between a release film and a substrate, and placing it in an ultraviolet lamp box for curing.

9. The preparation method according to claim 8, wherein: The thickness of the release film is 50-100 μm; And / or, the substrate is PET; And / or, the thickness of the substrate is 50-100 μm; And / or, the curing time is 5-8 min; and / or, the total light energy of the ultraviolet lamp box is 1300 - 1600 mJ / cm 2 ; And / or, the thickness of the cured adhesive film is 100-150 μm.

10. Application of an antioxidant optical adhesive in an electronic device, characterized in that The electronic device includes a nano silver conductive film, and the antioxidant optical adhesive is adhered to the nano silver conductive film; the antioxidant optical adhesive is an antioxidant optical adhesive according to claim 6 or 7, or an antioxidant optical adhesive obtained by the preparation method according to claim 8 or 9.

Images