Optically clear adhesive and methods of using the same, display module and display device

Abstract

The application relates to the technical field of impact-resistant materials, in particular to an optical transparent adhesive and a use method thereof, a display module and a display device. The application is used to solve the problem of poor impact resistance of a display module in the related art. An optical transparent adhesive comprises a base material and an impact-resistant material, the base material comprises an organic silicone adhesive, and the impact-resistant material comprises boron-containing polyorganosiloxane or monomers or prepolymers of the boron-containing polyorganosiloxane. The application is used to improve the impact resistance of the display module.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of impact-resistant materials, in particular to an optical transparent adhesive and a use method thereof, a display module and a display device. BACKGROUND

[0002] With the evolution of flexible forms of various terminal products such as folding screens and scroll screens, in order to achieve better bending performance, the overall thickness of the display module needs to be thinned, and with the thinning of the thickness of the product, the impact protection of key functional layers such as the display panel layer will be poor, which is not conducive to the improvement of the impact resistance of the display module. SUMMARY

[0003] Embodiments of the application provide an optical transparent adhesive and a use method thereof, a display module and a display device, to solve the problem of poor impact resistance of the display module in the related art.

[0004] To achieve the above-mentioned purpose, embodiments of the application adopt the following technical solutions:

[0005] In a first aspect, an optical transparent adhesive is provided, comprising: a base material, and an impact-resistant material, the base material comprising an organic silicone adhesive; the impact-resistant material comprising: a boron-containing polyorganosiloxane, or a monomer or prepolymer of the boron-containing polyorganosiloxane.

[0006] Polyorganosiloxane is the main body of organic silicone adhesive, the main chain is composed of alternating silicon-oxygen chain segments connected by silicon and oxygen atoms, and the side chain is various organic groups connected by silicon atoms. In this polymer, both Si-O bond structure similar to inorganic silicate and organic groups are contained, thereby combining organic properties and inorganic characteristics. The bond energy of Si-O bond is 451 kJ / mol, which is much larger than the bond energy of C-C bond in organic matter, so that the interatomic chemical bond is not easy to break and the substance is not easy to decompose under high temperature or radiation conditions. At the same time, polyorganosiloxane is also resistant to low temperature. Studies have shown that the Si-O-Si bond has a longer bond length and a larger bond angle, and the organic groups (such as methyl) connected to the silicon atom have a large rotational freedom around the Si-O bond axis. As a result of the movement, the intermolecular distance is increased and the intermolecular force is weakened, so that the interaction between the silicon-oxygen chains is small and the surface tension is small, and the physical and chemical properties are still excellent in low temperature state.

[0007] The special structure of polyorganosiloxane makes the adhesive with it as the main body have excellent high and low temperature resistance, water resistance, corrosion resistance, and atmospheric aging resistance, etc. It can be mixed by mixing silicon resin solution or silicone rubber, fillers, cross-linking agents, catalysts and other additives, and is suitable for bonding and sealing of metal, ceramic, glass and plastic parts.

[0008] In addition, by selecting or modifying the specific structure of polyorganosiloxane, the adhesive performance of silicone adhesives can be improved, and the silicone adhesives can have high light transmittance and prevent yellowing. Thus, they can be used in optically transparent adhesives to ensure good adhesion and high light transmittance of display modules, thereby improving lifespan and display effect.

[0009] Boron-containing polyorganosiloxanes refer to materials in which boron is doped into organosiloxanes. These materials exhibit a fluid dynamic at low strain rates, and when subjected to impact, they exhibit a solid state, thus consuming a large amount of energy. Therefore, these materials have the effects of impact resistance and buffering energy absorption.

[0010] In the embodiments of this application, the optically transparent adhesive comprising silicone adhesive and boron-containing polyorganosiloxane is used as the first optically transparent adhesive layer. On the one hand, this first optically transparent adhesive layer can achieve stress absorption and adhesion during bending, while also exhibiting significant impact resistance characteristics. It does not increase the overall thickness of the display module, yet it improves the impact resistance of the display module. On the other hand, compared with the use of acrylate materials as optically transparent adhesives in related technologies, silicone adhesive and boron-containing polyorganosiloxane have better compatibility, which can improve the application effect.

[0011] In one implementation of the first aspect, the boron-containing polysiloxane comprises 5% to 40% of the optically transparent adhesive by mass. That is, the mass percentage of the boron-containing polysiloxane in the optically transparent adhesive can be any value between 5% and 40%. For example, the mass percentage of the boron-containing polysiloxane in the optically transparent adhesive can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, etc. Experiments have shown that by controlling the mass percentage of the boron-containing polysiloxane in the optically transparent adhesive within the above range, the impact resistance of the display module can be effectively improved while ensuring the adhesive performance of the optically transparent adhesive.

[0012] In one implementation of the first aspect, the boron-containing polyorganosiloxane comprises one or more combinations of the following structural formulas:

[0013]

[0014] In formula (I), R1, R2, R3, R4, R5, R6, R7, R8, and R9 are selected from any one of alkyl, aryl, alkenyl, hydroxyl, and -OR, respectively; m is an integer from 1 to 100,000; n is an integer from 0 to 100,000; and i is an integer from 0 to 100,000. In formula (II), R... 10 R 11 R 12 R 13R 14 and R 15 R is selected from any one of alkyl, aryl, alkenyl, hydroxyl and -OR, j is an integer from 1 to 100000, and k is an integer from 0 to 100000; wherein R is selected from any one of aryl and alkyl.

[0015] In this implementation, boron-containing polyorganosiloxanes can be introduced into the main chain of the organosiloxane through borylation modification. The boron in the chain will form weak bonds and interactions with the oxygen atoms of adjacent chain segments. This dynamic equilibrium weak bonding will not affect the overall bending performance (such as modulus, creep, and springback) of the organosilicone optical adhesive in low strain rate scenarios of normal bending applications. However, when subjected to impact with a high strain rate, this weak bonding will absorb the impact energy and form strong coordination bonds. From a mechanical perspective, this means that when subjected to a high strain rate impact, the material will instantly increase multiple crosslinking sites with BO coordination bonds as the core, instantly increasing the intermolecular forces and dynamic crosslinking degree of the organosilicone and optical adhesive. The molecular entanglement between chain segments will intensify, and the elastic modulus of the colloid will be significantly improved, thus exhibiting impact resistance. After the impact, the dynamic instability of the BO coordination bonds will cause them to dissociate, and the material will return to its original soft state.

[0016] The aforementioned boron-containing polyorganosiloxane can be packaged separately from the aforementioned silicone adhesive. During use, the boron-containing polyorganosiloxane and silicone adhesive are mixed. In this process, depending on whether the end groups in the boron-containing polyorganosiloxane can react with the silicone adhesive, two possibilities exist: First, some or all of the end groups in the boron-containing polyorganosiloxane can react with the silicone adhesive. For example, in the presence of a platinum catalyst, the vinyl groups in the boron-containing polyorganosiloxane can undergo an addition reaction with the silanol groups in the silicone adhesive, resulting in a chemical bond. Second, none of the end groups in the boron-containing polyorganosiloxane can react with the silicone adhesive, resulting in a physical mixture.

[0017] In one implementation of the first aspect, in formula (I), R1, R2, R4, R5, R7, and R8 are selected from aryl or alkyl groups, respectively; in formula (II), R 10 R 11 R 13 and R 14The components are selected from aryl or alkyl groups, respectively. In this implementation, the boron-containing polyorganosiloxane can be kept in a chain-like structure rather than a cross-linked network structure. This allows the boron element within the chain to form weak bonds with the oxygen atoms of adjacent chain segments. This dynamically balanced weak bond does not affect the overall bending performance of the optically transparent adhesive in low-strain scenarios of normal bending applications. Thus, while maintaining the bending performance (such as modulus, creep, and springback) in low-strain scenarios, it can exhibit impact resistance when subjected to high-strain-rate impacts.

[0018] In one implementation of the first aspect, the boron-containing polyorganosiloxane contains boron atoms in a proportion of 0.1% to 10% of the total number of boron and silicon atoms. That is, the ratio of the number of boron atoms to the sum of the number of boron and silicon atoms is 0.1% to 10%, meaning that in a chain segment consisting of 100 boron and silicon atoms, the number of boron atoms is 0.1 to 10. In this implementation, by controlling the boron content within the aforementioned range, the impact resistance can be improved, and the boron-containing polyorganosiloxane can possess a certain degree of thickening effect.

[0019] In one implementation of the first aspect, the boron-containing polyorganosiloxane monomer or prepolymer comprises: any one or more of the following structural formulas (III) and (IV), and boric acid compounds.

[0020]

[0021] In equation (III), R 16 R 17 R 18 R is selected from alkyl, aryl, alkenyl, hydroxyl, and -OR, respectively, where r is an integer from 1 to 100,000; in formula (IV), R 19 R 20 R 21 and R 22 Each of the following is selected from chlorine, bromine, iodine, alkyl, aryl, alkenyl, hydroxyl and -OR, and at least one of them is chlorine, bromine or iodine; wherein R is selected from alkyl and aryl.

[0022] In this implementation, boron-containing polyorganosiloxanes can be obtained by reacting one or more of formulas (III) and (IV) with boric acid compounds. For example, if the monomer or prepolymer of the boron-containing polyorganosiloxane includes formula (III) and boric acid, the reaction equation of formula (III) and boric acid is as follows:

[0023]

[0024] It should be noted that the reaction equation for the reaction between formula (IV) and boric acid is similar to that for the reaction between formula (III) and boric acid described above, and will not be repeated here. The only difference is that the reaction between formula (III) and boric acid is a dehydration reaction, while the reaction between formula (IV) and boric acid is a dehydrohalogenation reaction. The above reaction equations can be carried out in the presence of a catalyst. In this case, the impact-resistant material may also include a catalyst. Examples of catalysts include one or a mixture of two of potassium hydroxide silanolate or ammonium hydroxide silanolate.

[0025] In one implementation of the first aspect, in equation (III), the R... 16 and R 17 Selected from alkyl or phenyl groups respectively; in formula (IV), R 19 R 20 R 21 and R 22 At least two of them are selected from alkyl or phenyl.

[0026] In this implementation, R1, R2, R4, R5, R7, R8, and R... are related to the boron-containing polyorganosiloxanes mentioned above. 10 R 11 R 13 and R 14 Similarly, when using the monomers or prepolymers of the aforementioned boron-containing polyorganosiloxanes to generate boron-containing polyorganosiloxanes, the boron-containing polyorganosiloxanes can also be kept in a chain-like structure rather than a cross-linked network structure, selected from aryl or alkyl phases respectively.

[0027] In one implementation of the first aspect, the boric acid compound includes any one or more combinations of boric acid and boric acid esters.

[0028] In one implementation of the first aspect, the silicone adhesive includes: a base adhesive, a crosslinking agent, and a catalyst.

[0029] In other words, in this implementation, the silicone adhesive can be an adhesive based on silicone resin or an adhesive based on silicone rubber. When the silicone adhesive is based on silicone resin, polydimethylsiloxane, methyltriethylsiloxane, etc., are commonly used as base materials, and cross-linked and cured using tetraalkoxysilane and tetraalkoxytitanate. When the silicone adhesive is based on silicone rubber, it can be formulated by adding other modifiers (such as silane coupling agents, tackifiers, plasticizers, etc.) using silicone resin as the base material. The most significant characteristic of silicone rubber is its high-temperature resistance, and it is available in both single-component and two-component forms.

[0030] In one implementation of the first aspect, the base adhesive comprises vinyl silicone oil, the crosslinking agent comprises hydrogen-containing silicone oil, and the catalyst comprises a platinum catalyst. Vinyl silicone oil has a silicon-oxygen chain as its main chain and active vinyl groups on its side chains, including terminal vinyl silicone oil and block vinyl silicone oil. It possesses all the functions of methyl silicone oil, and the terminal vinyl groups have strong reactivity, allowing it to undergo addition reactions with hydrogen-containing silicone oil under the action of a catalyst. It exhibits better compatibility with organic materials than methyl silicone oil and is easier to formulate with other organic materials. Given a fixed mass ratio of vinyl silicone oil to hydrogen-containing silicone oil and a fixed amount of vinyl groups in the vinyl silicone oil, the hydrogen content of the hydrogen-containing silicone oil plays a significant role in the adhesive strength of the two-component addition-type liquid silicone rubber.

[0031] In this implementation, the silicone adhesive is an adhesive based on a two-component addition-curing liquid silicone rubber. By rationally setting the molar mass of the vinyl silicone oil, the vinyl content, and the hydrogen content of the hydrogen-containing silicone oil, the adhesive performance of the silicone adhesive can be improved.

[0032] In one implementation of the first aspect, the vinyl silicone oil accounts for 50% to 70% of the mass of the optically transparent adhesive; the hydrogen-containing silicone oil accounts for 5% to 20% of the mass of the optically transparent adhesive; in 1 mol of vinyl silicone oil, the ratio of the number of vinyl groups to the number of silicon atoms in the vinyl silicone oil is 0.1% to 2%; in 1 mol of hydrogen-containing silicone oil, the ratio of the number of hydroxyl groups to the number of silicon atoms in the hydrogen-containing silicone oil is 0.015% to 0.15%.

[0033] The percentage of vinyl silicone oil in the optically transparent adhesive is 50%–70% by mass. This means any value within the range of 50%–70%, such as 50%, 55%, 60%, 65%, or 70%. The percentage of hydrogen-containing silicone oil in the optically transparent adhesive is 5%–20% by mass. This means any value within the range of 5%–20%, such as 5%, 10%, 15%, or 20%. In this process, vinyl silicone oil acts as both the raw rubber and the crosslinking agent; they undergo an addition reaction at room temperature to produce an organosilicon adhesive with a specific viscosity.

[0034] In 1 mol of vinyl silicone oil, the ratio of the number of vinyl atoms to the number of silicon atoms in the vinyl silicone oil is 0.1% to 2%. This means that for vinyl silicone oils with different molecular weights, the average ratio of the number of vinyl atoms to the number of silicon atoms in 1 mol of multiple different vinyl silicone oil molecules is 0.1% to 2%. In other words, in every 100 silicon atoms in a vinyl silicone oil chain segment, there are 0.1 to 2 vinyl atoms. In 1 mol of hydrogen-containing silicone oil, the ratio of the number of hydroxyl groups to the number of silicon atoms in the hydrogen-containing silicone oil is 0.015% to 0.15%. This means that for hydrogen-containing silicone oils with different molecular weights, the average ratio of the number of hydroxyl groups to the number of silicon atoms in 1 mol of multiple different hydrogen-containing silicone oil molecules is 0.015% to 0.15%. In other words, in every 100 silicon atoms in a hydrogen-containing silicone oil chain segment, there are 0.015 to 0.15 hydroxyl groups.

[0035] In this implementation, by limiting the mass ratio of vinyl silicone oil in the optically transparent adhesive, the mass ratio of hydrogen-containing silicone oil in the optically transparent adhesive, the vinyl content in the vinyl silicone oil, and the silanol content in the hydrogen-containing silicone oil to the above-mentioned ranges, the silicone rubber can have a suitable crosslinking density. This avoids the problem of silicone adhesives being too soft or too hard and brittle due to excessively high or low crosslinking density. At the same time, it can also maximize the adhesive performance of silicone adhesives.

[0036] In one implementation of the first aspect, the silicone adhesive further includes: MQ resin, wherein the MQ resin accounts for 5% to 20% of the mass of the optically transparent adhesive. MQ resin is a silicone resin with a relatively unique structure, consisting of Q-units (tetrafunctional siloxane units, expressed as SiO2). 4 / 2 Organosilicon compounds (represented by the formula R3SiO) and compounds containing M-units (monofunctional siloxane units, represented by the formula R3SiO) 1 / 2 The three-dimensional spherical silicone ester is generated by co-hydrolysis-condensation reaction of organosilicon compounds (represented by) .

[0037] While silicone rubber possesses a variety of excellent properties, its mechanical properties, such as compressive strength and tear strength, are relatively poor and cannot meet the requirements of the process. In these embodiments, by adding MQ resin, on the one hand, MQ resin can act as a reinforcing filler to increase the strength of silicone rubber. For example, the siloxane linkages in MQ resin can improve the mechanical strength, cohesive strength, peel strength, and high-temperature resistance of silicone rubber, thereby playing a reinforcing role. On the other hand, the organic part of MQ resin can improve its compatibility with silicone rubber and also play a role in increasing viscosity. At the same time, the addition of MQ resin does not cause the viscosity of the system to increase too quickly, which would be detrimental to subsequent operations, and the resulting silicone adhesive has good transparency.

[0038] In one implementation of the first aspect, the MQ resin comprises M-chain segments and Q-chain segments, wherein the ratio of the number of M-chain segments to the number of Q-chain segments is 0.5:1 to 2:1. The performance and application range of the MQ silicone resin mainly depend on its synthesis process conditions and the type and number of organic groups R in the molecule, i.e., the ratio of the number of M-chain segments to Q-chain segments; wherein the organic groups R mainly increase compatibility with other components and play a thickening role, SiO... 4 / 2 Linkages primarily serve as reinforcements to improve the strength of composite materials.

[0039] In this implementation, the reinforcement and adhesion effects can be maximized by controlling the mass ratio of M-links to Q-links within the range of 0.5:1 to 2:1.

[0040] In one implementation of the first aspect, the MQ resin further includes: D-units or T-units. The D-units are difunctional siloxane units (using R2SiO2). 2 / 2 (represented by RSiO), the T-unit is a trifunctional siloxane unit (represented by RSiO). 3 / 2 express).

[0041] In these embodiments, MDQ or MTQ resins can be obtained by introducing D- or T-terminus into the MQ resin, thus modifying the MQ resin.

[0042] In one implementation of the first aspect, the MQ resin further includes: a monovalent alkenyl group, such as a terminal alkenyl group.

[0043] In this implementation, the MQ resin containing terminal alkenyl groups can chemically bond with silicone rubber through a hydrosilylation reaction with hydrogen-containing silicone oil, thereby forming a three-dimensional network structure that provides reinforcement.

[0044] In a second aspect, a display module is provided, comprising: a display panel, a first functional layer, and a first optically transparent adhesive layer, wherein the display panel includes a display surface; the first functional layer is disposed on one side of the display surface of the display panel; and the first optically transparent adhesive layer is disposed between the first functional layer and the display panel, wherein the first optically transparent adhesive layer is formed by bonding and curing the display panel and the first functional layer with the optically transparent adhesive as described in the first aspect.

[0045] The display module provided in the second aspect has the same technical effect as the optically transparent adhesive provided in the first aspect, and will not be described in detail here.

[0046] In one implementation of the second aspect, the storage modulus of the first optically transparent adhesive layer at -40°C to 90°C is less than 300,000 Pa. The storage modulus can be, for example, a value measured according to a manual using a rheometer (Advanced Rheological Extension System, TA Instruments) at a frequency of 0.1 rad / s to 100 rad / s and a strain rate of 10% or less. In some embodiments, the storage modulus can be measured and derived based on temperature using a G2 series rheometer from TA Instruments at a frequency of 6.2 rad / s and a strain rate of 10% or less while simultaneously changing the temperature from -40°C to 90°C. The storage modulus is essentially Young's modulus, an indicator of a material's resilience after deformation, representing its ability to store elastic deformation energy. A smaller storage modulus results in less deformation of the first optically transparent adhesive layer upon impact, increasing its resistance to impact and ensuring the bending reliability of the display module.

[0047] In this implementation, the first optically transparent adhesive layer has a small energy storage modulus over a wide temperature range, indicating that the first optically transparent adhesive layer has good deformation characteristics, which can meet the application requirements of flexible and foldable display modules.

[0048] In one implementation of the second aspect, the glass transition temperature of the first optically transparent adhesive layer is less than -10℃. Amorphous polymers have three mechanical states: glassy state, elastic state, and viscous flow state. At low temperatures, the material is a rigid solid, similar to glass, and only undergoes very small deformation under external force; this state is the glassy state. As the temperature continues to rise to a certain range, the deformation of the material increases significantly, and the deformation becomes relatively stable within a certain temperature range; this state is the elastic state. As the temperature continues to rise, the deformation gradually increases again, and the material gradually becomes a viscous fluid, at which point the deformation cannot be recovered; this state is the viscous flow state. We usually call the transition between the glassy state and the elastic state the glass transition, and its corresponding transition temperature is the glass transition temperature.

[0049] In this implementation, the first optically transparent adhesive layer has a small glass transition temperature, which allows it to have good stability in a range of greater than or equal to -10°C.

[0050] In one implementation of the second aspect, when the thickness of the first optically transparent adhesive layer is 50 micrometers, the light transmittance of the first optically transparent adhesive layer is greater than 90% for light with a wavelength range of 400nm to 800nm. The high light transmittance of the first optically transparent adhesive layer will not affect the display.

[0051] In one implementation of the second aspect, the method further includes: a second functional layer and a second optically transparent adhesive layer; wherein the second functional layer and the second optically transparent adhesive layer are disposed between the display panel and the first optically transparent adhesive layer, and the display panel and the second functional layer are bonded together through the second optically transparent adhesive layer; or, the second functional layer and the second optically transparent adhesive layer are disposed on the side of the first functional layer away from the display panel, and the second functional layer and the first functional layer are bonded together through the second optically transparent adhesive layer.

[0052] Thirdly, a display device is provided, comprising: a display film assembly as described above, and a housing assembly. The housing assembly may include, for example, a front cover and a battery cover, wherein the display module is disposed on the side of the front cover opposite to the battery cover, for realizing the display function. Of course, the display device may also include: a battery, a motherboard, a small board, a camera module, and other functional components to realize the display function and other functions. The battery can provide power to the display module, the motherboard can support and electrically connect various electronic components (such as capacitors, inductors, CPUs (central processing units), battery management chips, charging management chips, camera modules, etc.), the small board can support and electrically connect electronic devices such as microphones and speakers, and the camera module can realize the camera function.

[0053] The display device provided in the third aspect has the same technical effect as the aforementioned display module, and will not be described in detail here.

[0054] Fourthly, a method for using the optically transparent adhesive as described in the first aspect is provided, comprising:

[0055] The first and second membrane layers are bonded together using a mixture of substrate material and impact-resistant material.

[0056] In one implementation of the fourth aspect, the silicone adhesive of the substrate material includes: a base adhesive, a crosslinking agent, and a catalyst. The bonding of the first and second film layers using a mixture of the substrate material and the impact-resistant material includes:

[0057] The mixed material is formed on a first film layer and / or a second film layer.

[0058] The base adhesive and crosslinking agent in the mixed material undergo a crosslinking reaction under the catalysis of a catalyst to bond the first film layer and the second film layer. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of a display device provided in an embodiment of this application;

[0060] Figure 2AA schematic diagram of the structure of a foldable display device when folded inward, as provided in an embodiment of this application;

[0061] Figure 2B A schematic diagram of the structure of a foldable display device when folded outwards, as provided in an embodiment of this application;

[0062] Figure 3 This is a cross-sectional structural diagram of a display module provided in an embodiment of this application;

[0063] Figure 4 This is a cross-sectional view of another display module provided in an embodiment of this application;

[0064] Figure 5 This is a cross-sectional view of another display module provided in an embodiment of this application;

[0065] Figure 6 A cross-sectional structural diagram of another display module provided for related technologies;

[0066] Figure 7 A cross-sectional structural diagram of another display module provided for related technologies;

[0067] Figure 8 This is a schematic diagram illustrating the working principle of a boron-containing polyorganosiloxane under impact, as provided in an embodiment of this application. Detailed Implementation

[0068] Embodiments of this application provide a display device 100, such as... Figure 1 As shown, the display device 100 includes a display module 10 and a housing assembly 20. The housing assembly 20 may include, for example, a front cover 21 and a battery cover 22, wherein the display module 10 is disposed on the side of the front cover 21 opposite to the battery cover 22, and is used to implement the display function.

[0069] In some embodiments, the display device 100 may further include other functional components such as a battery 30, a motherboard 40, a small board, and a camera module to realize display functions and other functions.

[0070] For example, battery 30 can provide power to display module 10, motherboard 40 can support and electrically connect various electronic components (such as capacitors, inductors, CPU (central processing unit), battery management chip, charging management chip, camera module, etc.), small board can support and electrically connect electronic devices such as microphone and speaker, and camera module can realize camera function.

[0071] Among them, the battery 30, motherboard 40, small board, camera module and other functional components can be set between the front shell 21 and the battery cover 22. The front shell 21 serves to support the display module 10, battery 30, motherboard 40, small board and camera module, while the battery cover 22 is used to protect the various electronic components on the motherboard 40 and small board.

[0072] In some embodiments, the display module 10 may be an LCD (Liquid Crystal Display) module, an OLED (organic light emitting diode) display module, an LED (light emitting diode) display module, etc. Correspondingly, the display device 10 may be an LCD display device, an OLED display device, an LED display device, etc. This display device 10 may also be referred to as an electronic product or terminal, and may include mobile phones, mobile computers, e-readers, tablet computers (portable Android devices, Pads), smart TVs, personal digital assistants (PDAs), and wearable smart products, etc. Wearable smart products may include, but are not limited to, media players, smartwatches, smart glasses, smart bracelets, etc.

[0073] In some embodiments, the display device 100 may be a foldable display device, in which case the display module 10 is a foldable display module. For example... Figure 2A and Figure 2B As shown, the display module 10 includes a bending area C and a non-bending area F, as... Figure 2A As shown, the display device 100 is a foldable phone, and it folds inward, as shown in the diagram. Figure 2B As shown, the display device 100 is a foldable mobile phone, and it is folded outwards.

[0074] Embodiments of this application provide a display module 10, such as Figure 3 As shown, it includes: a display panel 1, a first functional layer 2 and a first optically transparent adhesive layer 3. The display panel 1 includes a display surface 1a. The first functional layer 2 is disposed on one side of the display surface 1a of the display panel 1. The first optically transparent adhesive layer 3 is disposed between the first functional layer 2 and the display panel 1. The first optically transparent adhesive layer 3 is formed by bonding the display panel 1 and the first functional layer 2 with optically transparent adhesive and then curing them.

[0075] Here, taking the display module 10 as an OLED display module as an example, and the display panel 1 as an OLED display panel, the first functional layer 2 can be a cover or a polarizer.

[0076] In some embodiments, such as Figure 3 As shown, the display module 10 may further include a touch layer 101, which may be disposed between the display panel 1 and the first optically transparent adhesive layer 3. The touch layer 101 is used to receive touch signals to control the display panel 1.

[0077] Of course, in some embodiments, such as Figure 3 As shown, the display module 10 may further include a support layer 102, which is disposed on the side of the display panel 1 away from the display surface. An example of the support layer 102 is a back film. The support layer 102 and the display panel 1 are bonded together by a PSA (pressure sensitive adhesive) 103.

[0078] In some embodiments, such as Figure 3 As shown, the display module 10 further includes: a second functional layer 4 and a second optically transparent adhesive layer 5, the second functional layer 4 and the second optically transparent adhesive layer 5 being disposed between the display panel 1 and the first optically transparent adhesive layer 3, and the display panel 1 and the second functional layer 4 being bonded together through the second optically transparent adhesive layer 5; or, as shown... Figure 4 As shown, the second functional layer 4 and the second optically transparent adhesive layer 5 are disposed on the side of the first functional layer 2 away from the display panel 1, and the second functional layer 4 and the first functional layer 2 are bonded together by the second optically transparent adhesive layer 5.

[0079] In these embodiments, taking the first functional layer 2 as a cover plate as an example, the second functional layer 4 can be a polarizer. In this case, the second functional layer 4 and the second optically transparent adhesive layer 5 are disposed between the display panel 1 and the first optically transparent adhesive layer 3. Along the direction gradually away from the display panel 1, the second optically transparent adhesive layer 5, the second functional layer 4, the first optically transparent adhesive layer 3 and the first functional layer 2 are stacked in sequence. Taking the first functional layer 2 as a polarizer as an example, the second functional layer 4 can be a cover plate. In this case, the second functional layer 4 and the second optically transparent adhesive layer 5 are disposed on the side of the first functional layer 2 away from the display panel 1. Along the direction gradually away from the display panel 1, the first optically transparent adhesive layer 3, the first functional layer 2, the second optically transparent adhesive layer 5 and the second functional layer 4 are stacked in sequence.

[0080] In some embodiments, in order to better protect the display panel 1, such as Figure 5As shown, the display module 10 may further include a first cover plate 104 and a second cover plate 105. The first cover plate 104 and the second cover plate 105 are both disposed on one side of the display surface 1a of the display panel 1 and are arranged sequentially in the direction away from the substrate 1. The first cover plate 104 and the display panel 1 can be bonded together by a first optically transparent adhesive, and the second cover plate 105 and the first cover plate 104 can be bonded together by a second optically transparent adhesive. At this time, the first functional layer 2 can serve as the first cover plate 104, the second functional layer 4 can serve as the second cover plate 105, the first optically transparent adhesive layer 3 can serve as the first optically transparent adhesive, and the second optically transparent adhesive layer 5 can serve as the second optically transparent adhesive.

[0081] In some embodiments, the display module 10 can be a foldable display module. In this case, the display panel 1 is a foldable display panel. For example, the substrate used in the display panel 1 is a flexible substrate, such as PI (Polyimide). Meanwhile, the support layer 102 can also be a flexible layer.

[0082] In related technologies, for foldable display modules, in order to achieve better flexible bending characteristics, the thickness of the display module 10 needs to be reduced. For example, the thinner the foldable display module, the easier it is to bend, and a smaller bending radius can be obtained. However, as the thickness of the foldable display module is reduced, its impact resistance is worse. It can be seen that thickness and impact resistance are two mutually restrictive parameters.

[0083] In related technologies, to improve the impact resistance of foldable display modules, a film layer or an impact-resistant material layer can be added to the stack of the display module 10. For example... Figure 6 As shown, an impact-resistant material layer 6 is added under the cover plate, or, as... Figure 7 As shown, adding a protective film 7 to the cover plate surface can increase the impact resistance of the foldable display module. However, it also increases the thickness of the foldable display module, which in turn affects the bending performance of the display module 10, making bending difficult. Considering the overall thickness, adding an impact-resistant material layer 6 by reducing the thickness of other functional layers or optically transparent adhesive layers will affect the overall performance of the foldable display module and impose higher requirements on the material selection of each film layer.

[0084] Based on the above considerations, in some embodiments of this application, the OCA (Optically Clear Adhesive) used in the first optically transparent adhesive layer 3 includes: a base material and an impact-resistant material. The base material includes an organosilicon adhesive, and the impact-resistant material includes: a boron-containing polyorganosiloxane, or a monomer or prepolymer of a boron-containing polyorganosiloxane.

[0085] Silicone adhesives can be classified into two main categories according to their molecular structure: silicone resin adhesives and silicone rubber adhesives. According to their curing method, they can be classified into three categories: condensation type, addition type, and polymerization type. According to their curing temperature, they can be classified into three categories: high-temperature curing, low-temperature curing, and room-temperature curing.

[0086] Polyorganosiloxanes are the main component of silicone adhesives. The main chain consists of alternating silicon-oxygen linkages, while the side chains are various organic groups linked by silicon atoms. This polymer contains both Si-O bond structures similar to inorganic silicates and organic groups, thus possessing both organic and inorganic properties. The Si-O bond energy is 451 kJ / mol, much larger than the C-C bond energy in organic compounds. Therefore, under high temperature or radiation conditions, the interatomic chemical bonds are not easily broken, and the substance is not easily decomposed. Simultaneously, polyorganosiloxanes are also resistant to low temperatures. Studies have shown that the Si-O-Si bond length is relatively long, the bond angle is large, and the organic groups (such as methyl groups) attached to the silicon atoms have a large degree of rotational freedom around the Si-O bond axis. This movement increases the intermolecular distance and weakens intermolecular forces, resulting in weak interactions between silicon-oxygen chains, low surface tension, and excellent physicochemical properties even at low temperatures.

[0087] The special structure of polyorganosiloxane gives adhesives based on it excellent high and low temperature resistance, water resistance, corrosion resistance, and atmospheric aging resistance. They can be compounded from silicone resin solution or silicone rubber, fillers, crosslinking agents, catalysts and other additives, and are suitable for bonding and sealing metal, ceramic, glass and plastic parts.

[0088] In addition, by selecting or modifying the specific structure of polyorganosiloxane, the adhesive performance of silicone adhesive can be improved, and the silicone adhesive can have high light transmittance and prevent yellowing. Thus, it can be used in optically transparent adhesives to ensure good adhesive performance and high light transmittance of display module 10, thereby improving lifespan and display effect.

[0089] Boron-containing polyorganosiloxanes refer to materials doped with boron in organosiloxanes. These materials exhibit a fluid dynamic at low strain rates, and when subjected to impact, they exhibit a solid state, thus consuming a large amount of energy. Therefore, these materials possess impact resistance and buffering energy absorption effects.

[0090] In the embodiments of this application, the optically transparent adhesive comprising silicone adhesive and boron-containing polyorganosiloxane is used as the first optically transparent adhesive layer 3. On the one hand, this first optically transparent adhesive layer 3 can achieve stress absorption and adhesion during bending, while also exhibiting significant impact resistance characteristics. It does not increase the overall thickness of the display module 10, yet it improves the impact resistance of the display module 10. On the other hand, compared with the use of acrylate materials as optically transparent adhesives in related technologies, silicone adhesive and boron-containing polyorganosiloxane have better compatibility, which can improve the application effect.

[0091] There is no specific limit on the mass ratio of boron-containing polyorganosiloxane in the optically transparent adhesive. In practical applications, it can be selected according to actual needs to improve the impact resistance of the display module while ensuring the adhesion performance of the optically transparent adhesive.

[0092] In some embodiments, the boron-containing polysiloxane constitutes 5% to 40% of the optically transparent adhesive by mass. That is, the mass percentage of the boron-containing polysiloxane in the optically transparent adhesive can be any value between 5% and 40%. For example, the mass percentage of the boron-containing polysiloxane in the optically transparent adhesive can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, etc.

[0093] Experiments have shown that by controlling the mass ratio of boron-containing polyorganosiloxane in the optically transparent adhesive within the aforementioned range, the adhesion performance of the optically transparent adhesive can be ensured while effectively improving the impact resistance of the display module.

[0094] There are no specific restrictions on the packaging methods of the aforementioned silicone adhesive and impact-resistant materials. The silicone adhesive can be packaged separately from the impact-resistant materials. In this case, the impact-resistant materials are added to the silicone adhesive before use. Alternatively, the impact-resistant materials and silicone adhesive can be packaged together and then used directly.

[0095] Of course, in some embodiments, where the silicone adhesive and / or impact-resistant material comprises multiple components, one or more components of the silicone adhesive may be mixed together with one or more components of the impact-resistant material for packaging, and the components may be mixed together during use.

[0096] The composition of the aforementioned silicone adhesive is not specifically limited; as long as the silicone adhesive can perform its adhesive function, it can be used to bond the first functional layer and the display panel.

[0097] In some embodiments, the silicone adhesive includes a base adhesive, a crosslinking agent, and a catalyst.

[0098] In other words, in these embodiments, the silicone adhesive can be an adhesive based on silicone resin or an adhesive based on silicone rubber. When the silicone adhesive is based on silicone resin, polydimethylsiloxane, methyltriethylsiloxane, etc., are commonly used as base materials, and cross-linked and cured using tetraalkoxysilane and tetraalkoxytitanate. When the silicone adhesive is based on silicone rubber, it can be formulated by adding other modifiers (such as silane coupling agents, tackifiers, plasticizers, etc.) using silicone resin as the base material. The most significant characteristic of silicone rubber is its high-temperature resistance, and it is available in both single-component and two-component forms.

[0099] In some embodiments, the base adhesive includes vinyl silicone oil, the crosslinking agent includes hydrogen-containing silicone oil, and the catalyst includes a platinum catalyst.

[0100] Vinyl silicone oils are characterized by a silicon-oxygen chain as the main chain and active vinyl groups on the side chains. They include terminal vinyl silicone oils and block vinyl silicone oils, possessing all the functions of methyl silicone oils. The terminal vinyl groups exhibit strong reactivity and can undergo addition reactions with hydrogen-containing silicone oils under the action of catalysts. They also exhibit better compatibility with organic materials than methyl silicone oils and are easier to formulate with other organic materials. Given a fixed mass ratio of vinyl silicone oil to hydrogen-containing silicone oil and a fixed amount of vinyl groups in the vinyl silicone oil, the hydrogen content of the hydrogen-containing silicone oil plays a significant role in the adhesive strength of the two-component addition-type liquid silicone rubber.

[0101] In these embodiments, the silicone adhesive is an adhesive based on a two-component addition-curing liquid silicone rubber. By rationally setting the molar mass of the vinyl silicone oil, the vinyl content, and the hydrogen content of the hydrogen-containing silicone oil, the adhesive performance of the silicone adhesive can be improved.

[0102] In some embodiments, the vinyl silicone oil accounts for 50% to 70% of the optically transparent adhesive by mass, and the hydrogen-containing silicone oil accounts for 5% to 20% of the optically transparent adhesive by mass. In 1 mol of vinyl silicone oil, the ratio of the number of vinyl groups to the number of silicon atoms in the vinyl silicone oil is 0.1% to 2%; in 1 mol of hydrogen-containing silicone oil, the ratio of the number of hydroxyl groups to the number of silicon atoms in the hydrogen-containing silicone oil is 0.015% to 0.15%.

[0103] The percentage of vinyl silicone oil in optically transparent adhesives by mass is 50% to 70%. This means that the percentage of vinyl silicone oil in optically transparent adhesives by mass is any value within the range of 50% to 70%. For example, the percentage of vinyl silicone oil in optically transparent adhesives by mass can be 50%, 55%, 60%, 65%, or 70%, etc. The percentage of hydrogen-containing silicone oil in optically transparent adhesives by mass is 5% to 20%. This means that the percentage of hydrogen-containing silicone oil in optically transparent adhesives by mass is any value within the range of 5% to 20%. For example, the percentage of hydrogen-containing silicone oil in optically transparent adhesives by mass can be 5%, 10%, 15%, or 20%, etc.

[0104] In this process, vinyl silicone oil is used as raw rubber and vinyl silicone oil is used as a crosslinking agent. The two can undergo an addition reaction at room temperature to obtain an organosilicon adhesive with a certain viscosity.

[0105] In 1 mol of vinyl silicone oil, the ratio of the number of vinyl atoms to the number of silicon atoms in the vinyl silicone oil is 0.1% to 2%. This means that for vinyl silicone oils with different molecular weights, the average ratio of the number of vinyl atoms to the number of silicon atoms in 1 mol of multiple different vinyl silicone oil molecules is 0.1% to 2%. In other words, in every 100 silicon atoms in a vinyl silicone oil chain segment, there are 0.1 to 2 vinyl atoms. In 1 mol of hydrogen-containing silicone oil, the ratio of the number of hydroxyl groups to the number of silicon atoms in the hydrogen-containing silicone oil is 0.015% to 0.15%. This means that for hydrogen-containing silicone oils with different molecular weights, the average ratio of the number of hydroxyl groups to the number of silicon atoms in 1 mol of multiple different hydrogen-containing silicone oil molecules is 0.015% to 0.15%. In other words, in every 100 silicon atoms in a hydrogen-containing silicone oil chain segment, there are 0.015 to 0.15 hydroxyl groups.

[0106] In these embodiments, by limiting the mass ratio of vinyl silicone oil in the optically transparent adhesive, the mass ratio of hydrogen-containing silicone oil in the optically transparent adhesive, the vinyl content in the vinyl silicone oil, and the silane content in the hydrogen-containing silicone oil to the above-mentioned ranges, the silicone rubber can have a suitable crosslinking density, avoiding the problem of silicone adhesives being too soft or too hard and brittle due to excessively high or low crosslinking density. At the same time, the adhesive performance of the silicone adhesive can be maximized.

[0107] The molar mass of the vinyl silicone oil is not specifically limited. A vinyl silicone oil with a small molar mass can reduce the viscosity of the silicone adhesive, improve its fluidity, and to a certain extent increase the crosslinking density of the silicone rubber, giving it a certain tensile strength and hardness. A vinyl silicone oil with a large molar mass can improve the elasticity and elongation at break of the silicone rubber. In practical applications, the molar mass can be set reasonably according to the actual situation.

[0108] In some embodiments, the molar mass of the vinyl silicone oil is 400,000 g / mol to 800,000 g / mol.

[0109] That is, in these embodiments, the molar mass of the vinyl silicone oil is not exactly the same, but has a distribution range, such as the molar mass of the vinyl silicone oil being distributed in the range of 400,000 g / mol to 800,000 g / mol. Experiments have shown that by controlling the molar mass of the vinyl silicone oil within the above range, on the one hand, it can ensure that the molar mass of the vinyl silicone oil has a wider range, which is beneficial to improving the crosslinking performance of the silicone rubber. On the other hand, it can also enable the silicone rubber to have suitable tensile strength, hardness, elasticity and elongation, which can improve the performance.

[0110] In some embodiments, the catalyst comprises 0.001% to 0.005% by mass in the silicone adhesive. The catalyst includes a platinum catalyst, examples of which include chloroplatinic acid, Carstedt platinum catalyst, or Willing platinum catalyst.

[0111] In these embodiments, the mass percentage of the catalyst in the silicone adhesive can be any value between 0.001% and 0.005%, such as 0.001%, 0.002%, 0.003%, 0.004%, or 0.005%.

[0112] In some embodiments, the silicone adhesive may further include MQ resin, wherein the MQ resin accounts for 5% to 20% of the optically transparent adhesive by mass.

[0113] MQ resin is a type of organosilicon resin with a relatively unique structure. It consists of a Q-unit (a tetrafunctional siloxane unit, represented by the formula SiO2). 4 / 2 Organosilicon compounds (represented by the formula R3SiO) and compounds containing M-units (monofunctional siloxane units, represented by the formula R3SiO) 1 / 2 The three-dimensional spherical silicone ester is generated by co-hydrolysis-condensation reaction of organosilicon compounds (represented by) .

[0114] While silicone rubber possesses a variety of excellent properties, its mechanical properties, such as compressive strength and tear strength, are relatively poor and cannot meet the requirements of the process. In these embodiments, by adding MQ resin, on the one hand, MQ resin can act as a reinforcing filler to increase the strength of silicone rubber. For example, the siloxane linkages in MQ resin can improve the mechanical strength, cohesive strength, peel strength, and high-temperature resistance of silicone rubber, thereby playing a reinforcing role. On the other hand, the organic part of MQ resin can improve its compatibility with silicone rubber and also play a role in increasing viscosity. At the same time, the addition of MQ resin does not cause the viscosity of the system to increase too quickly, which would be detrimental to subsequent operations, and the resulting silicone adhesive has good transparency.

[0115] In some embodiments, the MQ resin includes M-chain segments and Q-chain segments, with the ratio of M-chain segments to Q-chain segments being 0.5:1 to 2:1.

[0116] The properties and applications of MQ silicone resin mainly depend on its synthesis process conditions and the type and number of organic groups R in the molecule, i.e., the ratio of M-units to Q-units. Among these, the organic groups R primarily increase compatibility with other components, acting as a thickener. (SiO2) 4 / 2 Linkages primarily serve as reinforcements to improve the strength of composite materials.

[0117] In these embodiments, the reinforcement and adhesion effects can be maximized by controlling the mass ratio of M-segments to Q-segments within the range of 0.5:1 to 2:1.

[0118] In some embodiments, the MQ resin further includes D-units or T-units. The D-unit is a difunctional siloxane unit (using R2SiO2). 2 / 2 (represented by RSiO), the T-unit is a trifunctional siloxane unit (represented by RSiO). 3 / 2 express).

[0119] In these embodiments, MDQ or MTQ resins can be obtained by introducing D- or T-terminus into the MQ resin, thus modifying the MQ resin.

[0120] In some embodiments, the MQ resin further includes a monovalent alkenyl group, such as a terminal alkenyl group.

[0121] In these embodiments, the MQ resin containing terminal alkenyl groups can chemically bond with silicone rubber through a hydrosilylation reaction with hydrogen-containing silicone oil, thereby forming a three-dimensional network structure that provides reinforcement.

[0122] Of course, in other embodiments, the MQ resin also includes: silane-based resin.

[0123] In these embodiments, the MQ resin can be a hydrogen-containing MQ resin, which can undergo a hydrosilylation reaction with vinyl silicone oil to chemically bond with the silicone rubber, and can also form a three-dimensional network structure to play a reinforcing role.

[0124] The structure of the aforementioned boron-containing polyorganosiloxane is not specifically limited; as long as the boron-containing polyorganosiloxane contains boron, it can provide impact resistance.

[0125] The components of the aforementioned silicone adhesive can be packaged separately or mixed together. When the components are packaged separately, they can be mixed together to obtain the corresponding silicone adhesive. When the components are packaged together, the components have already undergone a chemical reaction.

[0126] In some embodiments, boron-containing polyorganosiloxanes comprise one or more combinations of the following structural formulas:

[0127]

[0128]

[0129] In formula (I), R1, R2, R3, R4, R5, R6, R7, R8, and R9 are selected from any one of alkyl, aryl, alkenyl, hydroxyl, and -OR, respectively; m is an integer from 1 to 100,000; n is an integer from 0 to 100,000; and i is an integer from 0 to 100,000. In structural formula (II), R... 10 R 11 R 12 R 13 R 14 and R 15 R is selected from any one of alkyl, aryl, alkenyl, hydroxyl and -OR, j is an integer from 1 to 100000, and k is an integer from 0 to 100000; wherein R is selected from any one of aryl and alkyl.

[0130] In these embodiments, boron-containing polyorganosiloxanes can be introduced into the main chain of the organosiloxane through borylation modification, such as... Figure 8As shown, the boron element in the chain forms weak bonds with the oxygen atoms of adjacent chain segments. This dynamic equilibrium of weak bonding does not affect the overall bending performance (such as modulus, creep, and springback) of the silicone optical adhesive in low strain rate scenarios of normal bending applications. However, when subjected to impacts with high strain rates, this weak bonding absorbs the impact energy and forms strong coordination bonds. From a mechanical perspective, this means that when subjected to high strain rate impacts, the material instantly increases multiple cross-linking sites with BO coordination bonds as the core, instantly enhancing the intermolecular forces and dynamic cross-linking degree of the silicone and optical adhesive. The molecular entanglement between chain segments intensifies, and the elastic modulus of the colloid is significantly improved, thus exhibiting impact resistance. After the impact, the dynamic instability of the BO coordination bonds causes them to dissociate, and the material returns to its original soft state.

[0131] The boron-containing polyorganosiloxane can be packaged separately from the aforementioned silicone adhesive. During use, the boron-containing polyorganosiloxane and the silicone adhesive are mixed. In this process, depending on whether the end groups in the boron-containing polyorganosiloxane can react with the silicone adhesive, two possibilities exist: First, some or all of the end groups in the boron-containing polyorganosiloxane can react with the silicone adhesive. For example, in the presence of a platinum catalyst, the vinyl groups in the boron-containing polyorganosiloxane can undergo an addition reaction with the silanol groups in the silicone adhesive, resulting in a chemical bond. Second, none of the end groups in the boron-containing polyorganosiloxane can react with the silicone adhesive, resulting in a physical mixture.

[0132] Of course, in some embodiments, boron-containing polyorganosiloxanes can also be mixed with the above-mentioned silicone adhesives for packaging. In this case, the boron-containing polyorganosiloxanes can also chemically bond or physically mix with the silicone adhesives.

[0133] In some embodiments, in formula (I), R1, R2, R4, R5, R7, and R8 are each selected from aryl or alkyl groups; in formula (II), R 10 R 11 R 13 and R 14 They are selected from aryl or alkyl groups, respectively.

[0134] In these embodiments, the boron-containing polyorganosiloxane can be kept in a chain-like structure rather than a cross-linked network structure. This allows the boron element within the chain to form weak bonds with the oxygen atoms of adjacent chain segments. This dynamically balanced weak bond does not affect the overall bending performance of the optically transparent adhesive in low-strain scenarios of normal bending applications. Thus, while maintaining the bending performance (such as modulus, creep, and springback) in low-strain scenarios, it can exhibit impact resistance when subjected to high-strain-rate impacts.

[0135] In some embodiments, in the boron-containing polyorganosiloxane, the proportion of boron atoms in the total number of boron and silicon atoms is 0.1% to 10%. That is, the ratio of the number of boron atoms to the sum of the number of boron and silicon atoms is 0.1% to 10%, meaning that in a chain segment consisting of 100 boron and silicon atoms, the number of boron atoms is 0.1 to 10.

[0136] In these embodiments, by controlling the boron atom content within the above-mentioned range, the impact resistance can be improved, and the boron-containing polyorganosiloxane can have a certain thickening effect.

[0137] In some embodiments, the monomer or prepolymer of the boron-containing polyorganosiloxane includes any one or more of the following structural formulas (III) and (IV), and boric acid compounds.

[0138]

[0139] In equation (III), R 16 R 17 R 18 R is selected from alkyl, aryl, alkenyl, hydroxyl, and -OR, respectively, where r is an integer from 1 to 100,000; in formula (IV), R 19 R 20 R 21 and R 22 Each of the following is selected from chlorine, bromine, iodine, alkyl, aryl, alkenyl, hydroxyl and -OR, and at least one of them is chlorine, bromine or iodine; wherein R is selected from alkyl and aryl.

[0140] In these embodiments, boron-containing polyorganosiloxanes can be obtained by reacting one or more of formulas (III) and (IV) with boric acid compounds. For example, if the monomer or prepolymer of the boron-containing polyorganosiloxane includes formula (III) and boric acid, the reaction equation of formula (III) and boric acid is as follows:

[0141]

[0142] It should be noted that the reaction equation of formula (IV) and boric acid is similar to that of formula (III) and boric acid, and will not be repeated here. The only difference is that the reaction between formula (III) and boric acid is a dehydration reaction, while the reaction between formula (IV) and boric acid is a dehydrohalogenation reaction.

[0143] The above reaction equation can be carried out in the presence of a catalyst. In this case, the impact-resistant material may also include a catalyst. Examples of catalysts include one or a mixture of two of potassium hydroxide silanol or ammonium hydroxide silanol.

[0144] In some embodiments, in equation (III), R 16 and R 17 Selected from alkyl or phenyl groups respectively; in formula (IV), R 19 R 20 R 21 and R 22 At least two of them are selected from alkyl or phenyl.

[0145] In these embodiments, R1, R2, R4, R5, R7, R8, and R... 10 R 11 R 13 and R 14 Similarly, when using the monomers or prepolymers of the aforementioned boron-containing polyorganosiloxanes to generate boron-containing polyorganosiloxanes, the boron-containing polyorganosiloxanes can also be kept in a chain-like structure rather than a cross-linked network structure, selected from aryl or alkyl phases respectively.

[0146] It should be noted that the monomers or prepolymers of boron-containing polyorganosiloxanes can be packaged separately from the silicone adhesive or packaged together with the silicone adhesive; no specific limitation is made here.

[0147] To avoid reactions between the boron-containing polyorganosiloxane monomers or prepolymers and one or more components of the silicone adhesive, optionally, the boron-containing polyorganosiloxane monomers or prepolymers are packaged separately from the silicone adhesive.

[0148] In use, the boron-containing polyorganosiloxane monomers or prepolymers are first reacted at a certain temperature to generate boron-containing polyorganosiloxanes. Then, the boron-containing polyorganosiloxanes are mixed with silicone adhesives. This avoids the reaction between the boron-containing polyorganosiloxane monomers or prepolymers and one or more components in the silicone adhesive, which would hinder the formation of chains in the boron-containing polyorganosiloxanes and easily generate various by-products, leading to uncontrollable reaction products.

[0149] In some embodiments, borate compounds include any one or more combinations of boric acid and borate esters.

[0150] In some embodiments, the storage modulus of the first optically transparent adhesive layer 3 at -40°C to 90°C is less than 300,000 Pa.

[0151] The storage modulus can be a value measured, for example, using a rheometer (Advanced Rheological Extension System, TA Instruments) at a frequency of 0.1 rad / s to 100 rad / s and a strain rate of 10% or less, according to a manual.

[0152] In some embodiments, the storage modulus can be measured and derived based on temperature using a G2 series rheometer from TA Instruments at a frequency of 6.2 rad / s and a strain rate of 10% or less, while the temperature is changed from -40°C to 90°C.

[0153] The energy storage modulus is essentially Young's modulus, which is an indicator of the rebound of a material after deformation. It represents the material's ability to store elastic deformation energy. The smaller the energy storage modulus, the smaller the deformation of the first optically transparent adhesive layer 3 when subjected to impact, and the more resistant it is to impact, thus ensuring the bending reliability of the display module.

[0154] In these embodiments, the first optically transparent adhesive layer 3 has a small energy storage modulus over a wide temperature range, indicating that the first optically transparent adhesive layer 3 has good deformation characteristics, which can meet the application requirements of flexible and foldable display modules.

[0155] The lower limit of the energy storage modulus can be 1000 Pa.

[0156] In some embodiments, the glass transition temperature of the first optically transparent adhesive layer 3 is less than -10°C.

[0157] Amorphous polymers exist in three mechanical states: the glassy state, the elastic state, and the viscous flow state. At lower temperatures, the material is a rigid solid, similar to glass, and undergoes only very small deformation under external forces; this state is the glassy state. As the temperature continues to rise to a certain range, the deformation of the material increases significantly, and then stabilizes relatively within a certain temperature range; this state is the elastic state. With further increases in temperature, the deformation gradually increases again, and the material gradually becomes a viscous fluid, at which point the deformation cannot be reversed; this state is the viscous flow state. The transition between the glassy and elastic states is usually called the glass transition, and its corresponding transition temperature is called the glass transition temperature.

[0158] In these embodiments, the first optically transparent adhesive layer 3 has a low glass transition temperature, which enables the first optically transparent adhesive layer to have good stability in a range greater than or equal to -10°C.

[0159] In some embodiments, when the thickness of the first optically transparent adhesive layer 3 is 50 micrometers, the light transmittance of the first optically transparent adhesive layer 3 is greater than 90% for light with a wavelength range of 400nm to 800nm.

[0160] In these embodiments, the first optically transparent adhesive layer 3 has high light transmittance and will not affect the display.

[0161] The above describes an example where the first optically transparent adhesive layer 3 uses the optically transparent adhesive described above. Those skilled in the art will understand that when the display module 10 includes a second optically transparent adhesive layer 5, the second optically transparent adhesive layer 5 can also use the aforementioned optically transparent adhesive, which can further improve the impact resistance of the display module 10. Furthermore, when the display module 10 also includes a pressure-sensitive adhesive, the pressure-sensitive adhesive can also use the aforementioned optically transparent adhesive. In this case, the pressure-sensitive adhesive also has impact resistance properties, which can further improve the impact resistance of the display module.

[0162] Some embodiments of this application provide a method of using the optically transparent adhesive as described above, including:

[0163] The first and second membrane layers are bonded together using a mixture of substrate material and impact-resistant material.

[0164] Depending on whether the base material and impact-resistant material are packaged together, there are two possible scenarios. First, the base material and impact-resistant material are packaged separately. In this case, they can be mixed to obtain a composite material, which is then used to adhere the first and second film layers. Second, the base material and impact-resistant material are packaged together. In this case, the composite material can be directly used to adhere the first and second film layers.

[0165] Depending on whether the base material and the impact-resistant material react, the base material and the impact-resistant material can be physically mixed or have undergone a chemical reaction; no specific limitation is made here.

[0166] Regardless of the mixing method used, it will not affect the use of the base material and the impact-resistant material.

[0167] In some embodiments, the silicone adhesive includes: a base adhesive, a crosslinking agent, and a catalyst. Bonding a first film layer and a second film layer using a mixture of a substrate material and an impact-resistant material includes:

[0168] The mixed material is formed on the first film layer and / or the second film layer.

[0169] The mixture can be a fluid adhesive or a paste. It can be formed on the first and / or second film layers by coating or spraying.

[0170] The first and second films can be the display panel and the polarizer, respectively.

[0171] The base adhesive and crosslinking agent in the mixed material undergo a crosslinking reaction under the catalysis of a catalyst to bond the first and second film layers.

[0172] For example, the base adhesive and crosslinking agent in the mixture can undergo a crosslinking reaction under the catalysis of a catalyst at room temperature or under heating conditions, and the first and second film layers can be bonded by curing.

[0173] Based on the above specific embodiments, in order to objectively evaluate the technical effects of the technical solution provided in this application, the technical solution provided in this application will be described in detail and by way of example through the following comparative examples, experimental examples and simulation experiments.

[0174] It should be noted that in the following comparative examples and experimental cases, the illustrations are based on the case of display module 10 being a foldable display module.

[0175] Comparative Example

[0176] like Figure 5 As shown, in the display module provided in the comparative example, both the first optically transparent adhesive layer 3 and the second optically transparent adhesive layer 5 use acrylate as the optically transparent adhesive.

[0177] Experimental Example 1

[0178] like Figure 5 As shown, in the display module provided in Experimental Example 1, the first optically transparent adhesive layer 3 uses the optically transparent adhesive provided in the embodiments of this application. The specific composition of the optically transparent adhesive is shown in Table 1 below. The second optically transparent adhesive layer 5 uses acrylate as the optically transparent adhesive. The thickness of the first optically transparent adhesive layer 3 is the same as the thickness of the first optically transparent adhesive layer 3 in the comparative example, and the thickness of the second optically transparent adhesive layer 5 is the same as the thickness of the second optically transparent adhesive layer 5 in the comparative example.

[0179] Experimental Example 2

[0180] In the display module provided in Experimental Example 2, in addition to the first optically transparent adhesive layer 3 using the optically transparent adhesive provided in the embodiments of this application, the second optically transparent adhesive layer 5 also uses the optically transparent adhesive provided in the embodiments of this application, and its specific composition is the same as that of the optically transparent adhesive used in the first optically transparent adhesive layer 3 in Experimental Example 1.

[0181] Experimental Example 3

[0182] like Figure 5 As shown, in the display module provided in Experimental Example 3, the first optically transparent adhesive layer 3 uses the optically transparent adhesive provided in the embodiments of this application. The specific composition of the optically transparent adhesive is shown in Table 1 below. The second optically transparent adhesive layer 5 uses acrylate as the optically transparent adhesive. The thickness of the first optically transparent adhesive layer 3 is the same as the thickness of the first optically transparent adhesive layer 3 in the comparative example, and the thickness of the second optically transparent adhesive layer 5 is the same as the thickness of the second optically transparent adhesive layer 5 in the comparative example.

[0183] Experiment Example 4

[0184] In the display module provided in Experimental Example 4, in addition to the first optically transparent adhesive layer 3 using the optically transparent adhesive provided in the embodiments of this application, the second optically transparent adhesive layer 5 also uses the optically transparent adhesive provided in the embodiments of this application, and its specific composition is the same as that of the optically transparent adhesive used in the first optically transparent adhesive layer 3 in Experimental Example 3.

[0185] Experimental Example 5

[0186] like Figure 5 As shown, in the display module provided in Experimental Example 5, the first optically transparent adhesive layer 3 uses the optically transparent adhesive provided in the embodiments of this application. The specific composition of the optically transparent adhesive is shown in Table 1 below. The second optically transparent adhesive layer 5 uses acrylate as the optically transparent adhesive. The thickness of the first optically transparent adhesive layer 3 is the same as the thickness of the first optically transparent adhesive layer 3 in the comparative example, and the thickness of the second optically transparent adhesive layer 5 is the same as the thickness of the second optically transparent adhesive layer 5 in the comparative example.

[0187] Experimental Example 6

[0188] In the display module provided in Experimental Example 6, in addition to the first optically transparent adhesive layer 3 using the optically transparent adhesive provided in the embodiments of this application, the second optically transparent adhesive layer 5 also uses the optically transparent adhesive provided in the embodiments of this application, and its specific composition is the same as that of the optically transparent adhesive used in the first optically transparent adhesive layer 3 in Experimental Example 5.

[0189] Experimental Example 7

[0190] like Figure 5 As shown, in the display module provided in Experimental Example 7, the first optically transparent adhesive layer 3 uses the optically transparent adhesive provided in the embodiments of this application. The specific composition of the optically transparent adhesive is shown in Table 1 below. The second optically transparent adhesive layer 5 uses acrylate as the optically transparent adhesive. The thickness of the first optically transparent adhesive layer 3 is the same as the thickness of the first optically transparent adhesive layer 3 in the comparative example, and the thickness of the second optically transparent adhesive layer 5 is the same as the thickness of the second optically transparent adhesive layer 5 in the comparative example.

[0191] Experimental Example 8

[0192] In the display module provided in Experimental Example 8, in addition to the first optically transparent adhesive layer 3 using the optically transparent adhesive provided in the embodiments of this application, the second optically transparent adhesive layer 5 also uses the optically transparent adhesive provided in the embodiments of this application, and its specific composition is the same as that of the optically transparent adhesive used in the first optically transparent adhesive layer 3 in Experimental Example 7.

[0193] Verification Experiment

[0194] 1. The storage modulus of Experimental Examples 1 to 8 was tested using a G2 series rheometer from TA Instruments at a frequency of 6.2 rad / s and a strain rate of 10% at a temperature of 25℃. The test results are shown in Table 1 below.

[0195] 2. For example Figure 2A and Figure 2B As shown, the foldable display module has a bending area C and a non-bending area F. Due to the difference in the material of the support layer 102, the impact resistance characteristics of the bending area C and the non-bending area F of the display module 10 also differ significantly. Drop tests were conducted on the bending area C and the non-bending area F of the display modules 10 provided in Experimental Examples 1 to 8 using a 32.65g stainless steel ball. The lowest drop height of the ball when each display module 10 exhibited display defects (such as display abnormalities compared to before the test, such as bright / dark spots, bright / dark lines, etc.) was recorded. This allows for the characterization of the impact resistance characteristics. The specific test results are shown in Table 1 below.

[0196] Table 1

[0197]

[0198] As shown in Table 1, compared with Comparative Example 1, the impact resistance of the display modules in Experimental Examples 1 to 8 is significantly improved. In particular, when both the first optically transparent adhesive layer 3 and the second optically transparent adhesive layer 5 use the optically transparent adhesive provided in the embodiments of this application, the impact resistance of the display module 10 is even better. In addition, the study found that the impact resistance is best when the mass ratio of boron-containing polyorganosiloxane in the transparent optical adhesive is within 10% to 20%.

[0199] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optically transparent adhesive, characterized in that, include: A substrate material, said substrate material including silicone adhesive; Impact-resistant material, the impact-resistant material comprising: boron-containing polyorganosiloxane, or monomers or prepolymers of the boron-containing polyorganosiloxane; The boron-containing polyorganosiloxane comprises one or more combinations of the following structural formulas: In formula (I), R1, R2, R3, R4, R5, R6, R7, R8 and R9 are selected from any one of alkyl, aryl, alkenyl, hydroxyl and -OR, respectively, m is an integer from 1 to 100000, n is an integer from 0 to 100000, and i is an integer from 0 to 100000. In equation (II), R 10 R 11 R 12 R 13 R 14 and R 15 Each is selected from alkyl, aryl, alkenyl, hydroxyl and -OR, where j is an integer from 1 to 100,000 and k is an integer from 0 to 100,000. R is selected from either aryl or alkyl.

2. The optically transparent adhesive according to claim 1, characterized in that, The boron-containing polyorganosiloxane accounts for 5% to 40% of the mass of the optically transparent adhesive.

3. The optically transparent adhesive according to claim 1 or 2, characterized in that, In formula (I), R1, R2, R4, R5, R7 and R8 are selected from aryl or alkyl groups, respectively; In equation (II), R 10 R 11 R 13 and R 14 They are selected from aryl or alkyl groups, respectively.

4. The optically transparent adhesive according to claim 1 or 2, characterized in that, In the boron-containing polyorganosiloxane, the percentage of boron atoms in the total number of boron atoms and silicon atoms is 0.1% to 10%.

5. The optically transparent adhesive according to claim 1 or 2, characterized in that, The boron-containing polyorganosiloxane is obtained by reacting one or more of the following structural formulas (III) and (IV) with a boric acid compound; In equation (III), R 16 R 17 R 18 Each of the following is selected from alkyl, aryl, alkenyl, hydroxyl and -OR, where r is an integer from 1 to 100000; In equation (IV), R 19 R 20 R 21 and R 22 Each of the following is selected from chlorine, bromine, iodine, alkyl, aryl, alkenyl, hydroxyl and -OR, and at least one of them is chlorine, bromine or iodine; R is selected from either alkyl or aryl.

6. The optically transparent adhesive according to claim 5, characterized in that, In equation (III), the R 16 and R 17 Selected from alkyl or phenyl groups respectively; In equation (IV), the R 19 R 20 R 21 and R 22 At least two of them are selected from alkyl or phenyl.

7. The optically transparent adhesive according to claim 5, characterized in that, The boric acid compounds include any one or more combinations of boric acid and borate esters.

8. The optically transparent adhesive according to claim 1 or 2, characterized in that, The silicone adhesive comprises: a base adhesive, a crosslinking agent, and a catalyst.

9. The optically transparent adhesive according to claim 8, characterized in that, The base adhesive includes vinyl silicone oil, the crosslinking agent includes hydrogen-containing silicone oil, and the catalyst includes a platinum catalyst.

10. The optically transparent adhesive according to claim 9, characterized in that, The vinyl silicone oil accounts for 50% to 70% of the mass of the optically transparent adhesive; The hydrogen-containing silicone oil accounts for 5% to 20% of the mass of the optically transparent adhesive; In 1 mol of vinyl silicone oil, the ratio of the number of vinyl atoms to the number of silicon atoms in the vinyl silicone oil is 0.1% to 2%; In 1 mol of hydrogen-containing silicone oil, the ratio of the number of silane groups to the number of silicon atoms in the hydrogen-containing silicone oil is 0.015% to 0.15%.

11. The optically transparent adhesive according to claim 8, characterized in that, The silicone adhesive further includes MQ resin, wherein the MQ resin accounts for 5% to 20% of the mass of the optically transparent adhesive.

12. The optically transparent adhesive according to claim 11, characterized in that, The MQ resin comprises M-chain segments and Q-chain segments, wherein the ratio of the number of M-chain segments to the number of Q-chain segments is 0.5:1 to 2:

1.

13. The optically transparent adhesive according to claim 11 or 12, characterized in that, The MQ resin also includes: D-chain segments or T-chain segments.

14. The optically transparent adhesive according to claim 11 or 12, characterized in that, The MQ resin also includes: monovalent alkenyl groups.

15. A display module, characterized in that, include: Display panel, the display panel including a display surface; The first functional layer is located on one side of the display surface of the display panel; A first optically transparent adhesive layer is disposed between the first functional layer and the display panel. The first optically transparent adhesive layer is formed by bonding and curing the display panel and the first functional layer with the optically transparent adhesive as described in any one of claims 1 to 14.

16. The display module according to claim 15, characterized in that, The first optically transparent adhesive layer has a storage modulus of less than 300,000 Pa at temperatures ranging from -40°C to 90°C.

17. The display module according to claim 15, characterized in that, The glass transition temperature of the first optically transparent adhesive layer is less than -10°C.

18. The display module according to claim 15, characterized in that, When the thickness of the first optically transparent adhesive layer is 50 micrometers, the light transmittance of the first optically transparent adhesive layer is greater than 90% for light with a wavelength range of 400nm to 700nm.

19. The display module according to any one of claims 15 to 18, characterized in that, It also includes: a second functional layer and a second optically transparent adhesive layer; The second functional layer and the second optically transparent adhesive layer are disposed between the display panel and the first optically transparent adhesive layer, and the display panel and the second functional layer are bonded together by the second optically transparent adhesive layer; or, the second functional layer and the second optically transparent adhesive layer are disposed on the side of the first functional layer away from the display panel, and the second functional layer and the first functional layer are bonded together by the second optically transparent adhesive layer.

20. A display device, characterized in that, include: The display film assembly as described in any one of claims 15 to 19; And housing components.

21. A method of using the optically transparent adhesive as described in any one of claims 1 to 14, characterized in that, include: The first and second membrane layers are bonded together using a mixture of substrate material and impact-resistant material.

22. The method of using the optically transparent adhesive according to claim 21, characterized in that, The silicone adhesive of the substrate material includes: a base adhesive, a crosslinking agent, and a catalyst; The first and second membrane layers are bonded together using a mixture of substrate material and impact-resistant material, including: The mixed material is formed on a first film layer and / or a second film layer; The base adhesive and crosslinking agent in the mixed material undergo a crosslinking reaction under the catalysis of a catalyst to bond the first film layer and the second film layer.

Images