An adhesive film for a curved image display device, a method of manufacturing the same, and an image display device

Abstract

This invention discloses an adhesive film for a curved image display device, its preparation method, and the image display device thereof. The adhesive film has a glass transition temperature Tg ≥ -5℃ and ≤ 5℃; a storage modulus greater than 130,000 Pa at 25℃ and 1Hz; and withstands a 365nm LED light with a power of 100mW / cm². 2 After irradiation for 45 seconds, the loss factor at 120°C and 0.1Hz is less than 0.085. The adhesive film is made from acrylic derivative polymers and photoinitiator I. The adhesive film of this invention has the advantages of good adhesion, no bubbles after standing, and high reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of glue, in particular to a sticking adhesive film for a curved image display device, a preparation method thereof and an image display device. BACKGROUND

[0002] OCA (Optically Clear Adhesive) has the advantages of colorless transparency, light transmittance of more than 90%, good cementing strength, small curing shrinkage, and no yellowing, and is a special adhesive for cementing transparent optical elements (such as touch screens, displays, optical lenses, etc.). In recent years, the wide application of curved screen technology has put forward higher requirements for the performance of OCA. Because the traditional OCA optical adhesive tape does not have excellent mechanical tensile properties and filling properties, it is difficult to meet the effective filling of the bending position and the ink step difference filling, and the stretching strip bubbles, standing bubble rebound and reliability test bubble rebound problems are prone to occur at the curved corner.

[0003] CN115124928A reports a twice-curable OCA optical adhesive film, but it uses hexafluoroantimonate, which will inevitably cause yellowing during use.

[0004] CN110437792A synthesizes an OCA for curved bonding, which mainly selects polyurethane acrylate (PUA) as the main material, aiming to utilize its good mechanical properties, especially the high tensile strength. However, the weather resistance of the polyurethane component is poor, especially prone to hydrolysis under heat and moisture.

[0005] CN110358458A reports a multi-layer structure OCA that can be used for curved bonding, which has 3 layers of adhesive film in addition to two release films. The middle layer is a high-tensile-strength ethylene-vinyl acetate copolymer hot melt adhesive film, and the two sides are polyacrylate pressure-sensitive adhesive films. The OCA has good 3D bonding performance, but the production cost of the multi-layer structure OCA is too high, and the ethylene-vinyl acetate polymer is prone to hydrolysis to produce acetic acid, which is not suitable for use in electronic products.

[0006] Under this background, combined with the specific needs of the industry, it is urgent to develop a sticking adhesive film that has good bonding effect and reliability. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art and provide a sticking adhesive film for a curved image display device.

[0008] To achieve the above object, the technical scheme adopted by the present application is: an adhesive film for a curved image display device, characterized in that the adhesive film has a glass transition temperature Tg≥-5℃ and ≤5℃; a storage modulus at 25℃, 1Hz is greater than 130,000 Pa; the adhesive film has a loss factor less than 0.085 at 120℃, 0.1Hz after being irradiated for 45s; and the raw material of the adhesive film comprises the following components: 2 The raw material of the adhesive film comprises the following components:

[0009] 1) an acrylic derivative polymer comprising the following raw materials: a C4-C18 acrylate monomer, a hydrophilic monomer and a basic monomer;

[0010] 2) a photoinitiator I, which uses a hydrogen abstraction type ultraviolet photoinitiator and a cleavage type ultraviolet photoinitiator.

[0011] Preferably, the amount of the photoinitiator I is 0.5-1% of the mass of the acrylic derivative polymer.

[0012] As a specific embodiment, the C4-C18 acrylate monomer is selected from one or more of (methyl) butyl acrylate, (methyl) isooctyl acrylate, (methyl) isobornyl acrylate, (methyl) isobutyl acrylate, (methyl) tert-butyl acrylate, (methyl) cyclohexyl acrylate, (methyl) n-octyl acrylate, (methyl) dodecyl acrylate, (methyl) octadecyl acrylate and (methyl) isooctadecyl acrylate, and the addition amount of the C4-C18 acrylate monomer is 50-95% of the total mass of the raw materials of the acrylic derivative polymer.

[0013] As a specific embodiment, the hydrophilic monomer is selected from one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 4-hydroxybutyl acrylate, and the addition amount of the hydrophilic monomer is 4.5-30% of the total mass of the raw materials of the acrylic derivative polymer.

[0014] As a specific embodiment, the basic monomer is selected from one or more of acrylamide, acryloyl morpholine and N,N-dimethyl acrylamide, and the addition amount of the basic monomer is 0.5-20% of the total mass of the raw materials of the acrylic derivative polymer.

[0015] As a specific embodiment, the hydrogen abstraction type ultraviolet photoinitiator is selected from one or more of 4-methyl benzophenone, benzophenone and 4-acryloyl hydroxybenzoic acid phenone, and the amount of the hydrogen abstraction type ultraviolet photoinitiator is 0.1-1% of the mass of the acrylic derivative polymer.

[0016] As a specific embodiment, the cleavage type ultraviolet photoinitiator is selected from one or more of benzoin derivatives, benzoin ketone derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-amine alkyl phenone, acyl phosphine hydride, ester oxime ketone compound, aryl peroxide ester compound, halomethyl aryl ketone, organic sulfur-containing compound, and benzoyl formate, and the amount of the cleavage type ultraviolet photoinitiator is 0.1-2% of the mass of the acrylic derivative polymer.

[0017] Another object of the present application is to provide a method for preparing an adhesive film for a curved image display device, comprising the following steps:

[0018] 1) preparing an acrylic derivative polymer

[0019] In a reaction vessel with a thermometer, stirring device, and nitrogen injection tube, C4-C18 acrylate monomers, hydrophilic monomers, basic monomers, and photoinitiator II are added, stirred and mixed uniformly, and then subjected to nitrogen replacement at a wind speed of 100 mL / min, and then polymerized under a UV lamp;

[0020] 2) preparing an adhesive resin composition

[0021] When the solid content in the polymerization process of step 1) is increased by 12%±1%, photoinitiator I is added, stirred and dissolved uniformly, and then subjected to defoaming treatment under a vacuum condition of 0.95 MPa to obtain the required adhesive resin composition.

[0022] As a specific embodiment, the photoinitiator II uses a cleavage type photoinitiator.

[0023] A third object of the present application is to provide an image display device, wherein the layer on the visible side is adhered with the adhesive film for the image display device described above.

[0024] As a specific embodiment, the adhesive film for the image display device described in claim 1 is provided between the transparent protective plate and the touch panel, or between the transparent protective plate and the image display unit.

[0025] Due to the use of the above technical solutions, the present application has the following advantages compared with the prior art: the adhesive film for the curved image display device of the present application is polymerized from an acrylic derivative polymer and a photoinitiator, has a glass transition temperature of Tg≥-5℃ and ≤5℃, a storage modulus at 25℃, 1 Hz of greater than 130,000 Pa, and a loss factor at 120℃, 0.1 Hz of less than 0.085 after irradiation for 45s by a 365nm LED lamp at 100mW / cm 2 After irradiation for 45s, the loss factor at 120℃, 0.1 Hz is less than 0.085, so that the obtained adhesive sheet has the characteristics of fitting effect, non-rebound of standing air bubbles, and high reliability. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be further described in connection with specific examples.

[0027] Provided below is an adhesive film for curved image display devices, which has a glass transition temperature Tg≥-5°C and ≤5°C; a storage modulus at 25°C, 1 Hz of greater than 130,000 Pa; and a loss factor at 120°C, 0.1 Hz of less than 0.085 after irradiation for 45 seconds. 2 Provided below is an adhesive film for curved image display devices, which has a glass transition temperature Tg≥-5°C and ≤5°C; a storage modulus at 25°C, 1 Hz of greater than 130,000 Pa; and a loss factor at 120°C, 0.1 Hz of less than 0.085 after irradiation for 45 seconds.

[0028] The raw materials of the adhesive film include an acrylic derivative polymer and a photoinitiator I, the raw materials of the acrylic derivative polymer include isooctyl acrylate, isooctyl methacrylate, isobornyl acrylate, hydroxyethyl acrylate, acryloyl morpholine, and acrylamide; and the photoinitiator I uses 4-acryloyloxybenzophenone and benzil dimethyl ketal.

[0029] Provided below is an adhesive film for curved image display devices, which has a glass transition temperature Tg≥-5°C and ≤5°C; a storage modulus at 25°C, 1 Hz of greater than 130,000 Pa; and a loss factor at 120°C, 0.1 Hz of less than 0.085 after irradiation for 45 seconds.

[0030] Example 1

[0031] Into a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen gas injection tube, isooctyl acrylate 60.5 g, isooctyl methacrylate 14.0 g, isobornyl acrylate 5.0 g, hydroxyethyl acrylate 12.0 g, acryloyl morpholine 5.0 g, acrylamide 3.5 g, and benzil dimethyl ketal 0.03 g were added, and the mixture was stirred and mixed uniformly while being replaced with nitrogen gas at a flow rate of 100 mL / min. Subsequently, polymerization was performed under a 1.0 mW / cm 2 of a 365 nm LED lamp, and the solid content was increased to 12%. Subsequently, 4-acryloyloxybenzophenone (ABP) 0.4 g and benzil dimethyl ketal 0.2 g were added, and the mixture was stirred and dissolved uniformly, and then was degassed under a vacuum of 0.95 MPa for 2 hours, to obtain an adhesive resin composition for adhesive sheets.

[0032] Subsequently, the adhesive resin composition for adhesive sheets thus obtained was dropped on a polyethylene terephthalate (PET) release film (release surface-contact adhesive resin composition), and then another PET release film was overlaid thereon (release surface-contact adhesive resin composition), and the adhesive resin composition for adhesive sheets was coated into a sheet shape using a roll, and was irradiated with ultraviolet rays (intensity: 2 mW / cm 2 , energy: 300 mJ / cm 2 ) using an ultraviolet irradiation device, to obtain a transparent adhesive sheet.

[0033] Example 2

[0034] In a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen gas injection tube, isooctyl acrylate 51.0 g, isooctyl methacrylate 14.0 g, isobornyl acrylate 14.5 g, hydroxyethyl acrylate 12.0 g, acryloyl morpholine 5.0 g, acrylamide 3.5 g, and benzoyl dimethyl ether 0.03 g were added, and nitrogen gas was replaced while stirring and mixing them uniformly at a wind volume of 100 mL / min. Thereafter, polymerization was performed under a 365 nm LED lamp of 1.0 mW / cm 2 After the solid content was increased to 12%, 4-acryloyloxybenzophenone (ABP) 0.4 g and benzoyl dimethyl ether 0.2 g were further added, and after stirring and dissolving them uniformly, the resultant was degassed under a vacuum of 0.95 MPa for 2 hours to obtain an adhesive sheet for an adhesive resin composition.

[0035] Thereafter, the adhesive sheet for an adhesive resin composition obtained in the above was dropped on a polyethylene terephthalate (PET) release film (a release surface-contact adhesive resin composition), and then another PET release film was overlaid thereon (a release surface-contact adhesive resin composition), and the adhesive sheet for an adhesive resin composition was coated in a sheet shape using a roll, and ultraviolet rays were irradiated using an ultraviolet irradiation device (intensity: 2 mW / cm 2 , energy: 300 mJ / cm 2 ) to obtain a transparent adhesive sheet.

[0036] Example 3

[0037] In a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen gas injection tube, isooctyl acrylate 51.0 g, isooctyl methacrylate 14.0 g, isobornyl acrylate 14.5 g, hydroxyethyl acrylate 12.0 g, acryloyl morpholine 5.0 g, acrylamide 3.5 g, and benzoyl dimethyl ether 0.03 g were added, and nitrogen gas was replaced while stirring and mixing them uniformly at a wind volume of 100 mL / min. Thereafter, polymerization was performed under a 365 nm LED lamp of 1.0 mW / cm 2 After the solid content was increased to 12%, 4-acryloyloxybenzophenone (ABP) 0.4 g and benzoyl dimethyl ether 0.2 g were further added, and after stirring and dissolving them uniformly, the resultant was degassed under a vacuum of 0.95 MPa for 2 hours to obtain an adhesive sheet for an adhesive resin composition.

[0038] Thereafter, the adhesive sheet for an adhesive resin composition obtained in the above was dropped on a polyethylene terephthalate (PET) release film (a release surface-contact adhesive resin composition), and then another PET release film was overlaid thereon (a release surface-contact adhesive resin composition), and the adhesive sheet for an adhesive resin composition was coated in a sheet shape using a roll, and ultraviolet rays were irradiated using an ultraviolet irradiation device (intensity: 2 mW / cm 2 , energy: 300 mJ / cm2 ), a transparent adhesive sheet was obtained.

[0039] Comparative Example 1

[0040] In a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen gas injection tube, isooctyl acrylate 62.5 g, isooctyl methacrylate 14.0 g, isobornyl acrylate 5.0 g, hydroxyethyl acrylate 12.0 g, acryloyl morpholine 3.0 g, acrylamide 3.5 g, and benzoyl dimethyl ether 0.03 g were added, and nitrogen replacement was performed at a wind rate of 100 mL / min while stirring to mix them uniformly. Thereafter, polymerization was performed under a 365 nm LED lamp at 1.0 mW / cm 2 , and after the solid content was increased to 12%, 4-acryloyloxybenzophenone (ABP) 0.4 g and benzoyl dimethyl ether 0.2 g were added, and after stirring and dissolution, defoaming was performed under a vacuum at 0.95 MPa for 2 hours, to obtain an adhesive resin composition for an adhesive sheet.

[0041] Thereafter, the adhesive resin composition for an adhesive sheet obtained above (adhesive resin composition for a release surface) was dropped on a polyethylene terephthalate (PET) release film, and another PET release film was overlaid thereon (adhesive resin composition for a release surface), and the adhesive resin composition for an adhesive sheet was coated into a sheet shape using a roll, and ultraviolet rays were irradiated using an ultraviolet irradiation device (intensity: 2 mW / cm 2 , energy: 300 mJ / cm 2 ), to obtain a transparent adhesive sheet.

[0042] Comparative Example 2

[0043] In a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen gas injection tube, isooctyl acrylate 62.5 g, isooctyl methacrylate 14.0 g, isobornyl acrylate 5.0 g, hydroxyethyl acrylate 12.0 g, acryloyl morpholine 3.0 g, acrylamide 3.5 g, and benzoyl dimethyl ether 0.03 g were added, and nitrogen replacement was performed at a wind rate of 100 mL / min while stirring to mix them uniformly. Thereafter, polymerization was performed under a 365 nm LED lamp at 1.0 mW / cm 2 , and after the solid content was increased to 12%, 4-acryloyloxybenzophenone (ABP) 0.4 g and benzoyl dimethyl ether 0.2 g were added, and after stirring and dissolution, defoaming was performed under a vacuum at 0.95 MPa for 2 hours, to obtain an adhesive resin composition for an adhesive sheet.

[0044] After that, the adhesive sheet adhesive resin composition obtained in the above was dropped on a polyethylene terephthalate (PET) release film (release surface-contact adhesive resin composition), and another PET release film was overlaid thereon (release surface-contact adhesive resin composition), and the adhesive sheet adhesive resin composition was coated into a sheet shape with a roll, and ultraviolet rays were irradiated using an ultraviolet irradiation device (intensity: 2 mW / cm 2 , energy: 300 mJ / cm 2 ), to obtain a transparent adhesive sheet.

[0045] Comparative Example 3

[0046] In a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen gas injection tube, 56.0 g of isooctyl acrylate, 14.0 g of isooctyl methacrylate, 9.5 g of isobornyl acrylate, 12.0 g of hydroxyethyl acrylate, 5.0 g of acryloyl morpholine, 3.5 g of acrylamide, and 0.03 g of benzoyl dimethyl ether were added, and nitrogen replacement was performed at a wind speed of 100 mL / min while stirring to mix them uniformly. After that, polymerization was performed under a 365 nm LED lamp at 1.0 mW / cm 2 , and after the solid content was increased to 12%, 0.2 g of 4-acryloyloxybenzophenone (ABP) and 0.2 g of benzoyl dimethyl ether were added, and after stirring and dissolving them uniformly, defoaming was performed under a vacuum at 0.95 MPa for 2 hours, to obtain an adhesive sheet adhesive resin composition.

[0047] After that, the adhesive sheet adhesive resin composition obtained in the above was dropped on a polyethylene terephthalate (PET) release film (release surface-contact adhesive resin composition), and another PET release film was overlaid thereon (release surface-contact adhesive resin composition), and the adhesive sheet adhesive resin composition was coated into a sheet shape with a roll, and ultraviolet rays were irradiated using an ultraviolet irradiation device (intensity: 2 mW / cm 2 , energy: 300 mJ / cm 2 ), to obtain a transparent adhesive sheet.

[0048] <TEST>

[0049] The adhesive sheets obtained in the above examples and comparative examples were evaluated according to the following evaluation methods, and the evaluation results are shown in Table 1.

[0050] (1) Measurement of glass transition temperature, loss elastic modulus, and storage elastic modulus

[0051] An adhesive sheet having a thickness of 0.5 mm, a width of 10 mm, and a length of 10 mm was prepared, and a wide-range dynamic viscoelasticity measuring device (Solids Analyzer RSA-II, manufactured by Pheometric Scientific) was used to measure the adhesive sheet in a share sandwich mode at a frequency of 1.0 Hz, a measurement temperature range of -40 to 80°C, and a temperature increase rate of 5°C / min.

[0052] The glass transition temperature (Tg) of the present application is the temperature at which a peak of tan δ is observed in the above measurement temperature range. When two or more peaks of tan δ are observed in the temperature range, the temperature at which the tan δ value shows a maximum is regarded as the glass transition temperature.

[0053] (II) Measurement of 0.1 Hz Loss Factor at 120°C

[0054] An adhesive sheet having a thickness of 0.5 mm, a width of 10 mm, and a length of 10 mm was prepared, and a wide-range dynamic viscoelasticity measuring device (Solids Analyzer RSA-II, manufactured by Pheometric Scientific) was used to measure the adhesive sheet in a frequency scan mode at a temperature of 120°C and a frequency range of 0.01 Hz to 10 Hz, and the loss factor at 0.1 Hz was measured.

[0055] (III) Evaluation of Lamination Effect

[0056] The prepared adhesive sheet (adhesive film thickness: 150 μm) was attached to an LED module in an appropriate size, and was laminated using a rubber roll (roll diameter: 50 mm, roll width: 210 mm) at a load of 2 kg at 25°C and atmospheric pressure. Subsequently, the display module and the curved glass cover plate were laminated in a laminator (Toyota TPL-0512MH) under the following conditions: room temperature, 1000 Pa, and a pressing condition of 0.2 MPa for 10 seconds. Then, the laminate was degassed at 45°C and 0.4 MPa for 15 minutes, and the presence or absence of defects such as bubbles was observed. If bubbles were present, the laminate was regarded as having poor filling properties. Subsequently, the laminate was left to stand at room temperature for 24 hours, and if bubbles were present, the laminate was regarded as having poor standing bubble return properties.

[0057] (IV) Reliability Evaluation

[0058] The reliability refers to the ability of the adhesive film to withstand bubbles, floating, and peeling after lamination under various environmental conditions, and the evaluation method is as follows.

[0059] The (glass-adhesive film-display module) assembly was irradiated with ultraviolet light at an energy of 4500 mJ / cm 2After the energy is cured, the sample is placed at 85℃, 85% RH for 500 hours, and then observed for bubbles after cooling to room temperature. If bubbles are observed, the sample is considered to be defective, otherwise, the sample is considered to be acceptable.

[0060] Table 1

[0061]

[0062] As shown in Table 1, when the glass transition temperature Tg of the adhesive film is between -5℃ and 5℃, the storage modulus at 25℃, 1 Hz is greater than 130,000 Pa, the loss factor at 120℃, 0.1 Hz is less than 0.085 after irradiation by a 365 nm LED lamp at 100 mW / cm2for 45 s, the bonding effect of the adhesive sheet is excellent, no bubbles are generated after standing, and the reliability is good.

[0063] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. An adhesive film for a curved image display device, characterized in that, The adhesive film has a glass transition temperature Tg ≥ -5℃ and ≤ 5℃; at 25℃, its storage modulus at 1Hz is greater than 130,000 Pa; the adhesive film is tested with a 365nm LED lamp at 100mW / cm². 2 After irradiation for 45 seconds, the loss factor at 120°C and 0.1Hz is less than 0.

085. The raw material of the adhesive film is composed of the following components: 1) An acrylic derivative polymer, comprising the following raw materials: C4-C18 acrylate monomers, hydrophilic monomers, and basic monomers, wherein the amount of C4-C18 acrylate monomers added accounts for 50-95% of the total mass of the acrylic derivative polymer raw materials; the amount of hydrophilic monomers added accounts for 4.5-30% of the total mass of the acrylic derivative polymer raw materials; and the amount of basic monomers added accounts for 0.5-20% of the total mass of the acrylic derivative polymer raw materials. The hydrophilic monomers are selected from one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate; and the basic monomers are selected from one or more of acrylamide, acryloylmorpholine, and N,N-dimethylacrylamide. 2) Photoinitiator I, wherein the photoinitiator I adopts a hydrogen-abstracting ultraviolet photoinitiator and a pyrolysis type ultraviolet photoinitiator.

2. The adhesive film for the curved image display device according to claim 1, characterized in that, The C4-C18 acrylate monomer is selected from one or more of the following: butyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, and isooctadecyl methacrylate.

3. The adhesive film for the curved image display device according to claim 1, characterized in that, The hydrogen-abstracting ultraviolet photoinitiator is selected from one or more of 4-methylbenzophenone, benzophenone, and 4-acryloylhydroxybenzoic acid benzophenone, and the amount of the hydrogen-abstracting ultraviolet photoinitiator is 0.1-1% of the mass of the acrylic derivative polymer.

4. The adhesive film for the curved image display device according to claim 1, characterized in that, The pyrolytic ultraviolet photoinitiator is selected from one or more of benzoin derivatives, benzoyl ketal derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenyl ketone, α-aminealkyl phenyl ketone, acylphosphine hydride, esterified oxime ketone compound, aryl peroxide ester compound, halomethyl aromatic ketone, organic sulfur-containing compound, and benzoyl carboxylate. The amount of the pyrolytic ultraviolet photoinitiator is 0.1-2% of the mass of the acrylic derivative polymer.

5. A method for preparing an adhesive film for a curved image display device as described in any one of claims 1 to 4, characterized in that, Includes the following steps: 1) Preparation of acrylic derivative polymers In a reaction vessel equipped with a thermometer, a stirring device, and a nitrogen injection tube, C4-C18 acrylate monomers, hydrophilic monomers, basic monomers, and photoinitiator II are added, stirred and mixed evenly, and nitrogen is purged at a flow rate of 100 mL / min, followed by polymerization under a UV lamp. 2) Preparation of adhesive resin composition When the solid content increases by 12% ± 1% during the polymerization process in step 1), photoinitiator I is added, and after stirring and dissolving evenly, the mixture is degassed under a vacuum of 0.95 MPa to obtain the desired adhesive resin composition. The photoinitiator II is a pyrolysis-type photoinitiator.

6. A curved surface image display device, wherein, The visible side has a layer adhered by an adhesive film to the curved image display device of claim 1.

7. The curved surface image display device according to claim 6, characterized in that, An adhesive film for a curved image display device as described in claim 1 is provided between the transparent protective plate and the touch panel or between the transparent protective plate and the image display unit.

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