Multi-layer folding OCA and preparation method thereof

Abstract

The invention relates to the technical field of electronic display, in particular to a multilayer folded OCA (optically clear adhesive) which comprises the following components in parts by mass: 97-99 parts of acrylic acid (ester) resin, 0.1-1 part of a cross-linking agent, 0.1-0.5 part of a silane coupling agent and 0.05-1 part of a free radical initiator. The multi-layer folding OCA is of a sandwich structure. According to the invention, the performance contradiction that a single-layer OCA cannot be considered is successfully solved, so that folding equipment can still keep good flexibility at low temperature, the problems of modulus increase and brittleness increase caused by low temperature are effectively reduced, and the risk of crease generation is reduced; the high adhesive force ensures the firm bonding between the OCA and the display component, the reliability and the stability of the equipment are greatly improved, and the possibility of display failure and component falling caused by infirm bonding is reduced.

Description

Technical Field

[0001] The present invention relates to the field of electronic display technology, and in particular to a multi-layer folded OCA and a preparation method thereof. Background Art

[0002] In today's display technology field, OCA plays a vital role in various display devices. However, the traditional single-layer OCA structure has significant limitations in performance. Single-layer OCA often finds it difficult to simultaneously meet multiple performance requirements such as low modulus at low temperature, high creep and high recovery, and good adhesion. In low-temperature environments, single-layer OCA usually exhibits a higher modulus, resulting in insufficient flexibility and inability to adapt to the frequent bending of folding devices. At the same time, its creep and recovery properties are also unsatisfactory, making it difficult to effectively cope with the stress changes caused by folding during long-term use, which can easily cause creases and damage.

[0003] In addition, it is difficult for a single-layer OCA to achieve the ideal level of adhesion while ensuring other properties. Insufficient adhesion may result in a loose bond between the OCA and the display component, affecting the display effect and the reliability of the device; while excessive adhesion may cause difficulties in repairing or replacing components. Due to the contradictory relationship between these properties, single-layer OCA faces many challenges when applied to folding devices, which limits the further development and widespread application of folding display technology. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a multi-layer folding OC to solve the above problems.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a multi-layer folded OCA, the multi-layer folded OCA comprises the following components by weight:

[0006]

[0007]

[0008] The multi-layer folded OCA is a sandwich structure. The multi-layer folded OCA with a sandwich structure can provide high adhesion and cohesion, and at the same time meet multiple performance requirements such as low modulus at low temperature, high creep high recovery and good adhesion.

[0009] As a further solution of the present invention, the multi-layer folded OCA includes an acrylic elastomer layer, and the upper and lower sides of the acrylic elastomer layer are respectively connected to acrylic pressure-sensitive adhesive layers. The acrylic pressure-sensitive adhesive layer has the characteristics of low modulus, high adhesion, high creep and low recovery, and the acrylic elastomer layer has the characteristics of high modulus.

[0010] As a further embodiment of the present invention, the acrylic (ester) pressure-sensitive adhesive layer comprises the following components in parts by weight:

[0011] 80-95 parts of acrylic acid (ester) soft monomer

[0012] 5-20 parts of acrylic acid (ester) functional monomer,

[0013] 0.1-0.5 parts of free radical initiator;

[0014] The acrylic acid (ester) pressure-sensitive adhesive layer is prepared by polymerizing acrylic acid (ester) soft monomers, acrylic acid (ester) functional monomers and free radical initiators.

[0015] As a further solution of the present invention, the molecular weight of the acrylic (ester) pressure-sensitive adhesive is 200,000-1,000,000; the thickness of the acrylic (ester) pressure-sensitive adhesive is 5-50 um.

[0016] As a further solution of the present invention, the molecular weight of the acrylic (ester) pressure-sensitive adhesive is 300,000-800,000; the thickness of the acrylic (ester) pressure-sensitive adhesive is 5-25 um.

[0017] As a further solution of the present invention, the molecular weight of the acrylic (ester) pressure-sensitive adhesive is 300,000-500,000.

[0018] As a further embodiment of the present invention, the acrylic (ester) elastomer layer comprises the following components in parts by weight:

[0019] Acrylic acid (ester) soft monomer 95-99 parts

[0020] 1-5 parts of acrylic acid (ester) functional monomer, 0.1-0.5 parts of free radical initiator;

[0021] The acrylic (ester) elastomer layer is prepared by polymerizing acrylic (ester) soft monomers, acrylic (ester) functional monomers and free radical initiators.

[0022] As a further solution of the present invention, the molecular weight of the acrylic (ester) elastomer is greater than 5 million; the thickness of the acrylic (ester) elastomer is 10-100 um.

[0023] As a further solution of the present invention, the molecular weight of the acrylic (ester) elastomer is 6-8 million; the thickness of the acrylic (ester) elastomer is 10-50 um.

[0024] As a further embodiment of the present invention, the acrylic acid (ester) soft monomer includes but is not limited to 2-ethylhexyl (meth)acrylate or n-octyl (meth)acrylate or n-decyl (meth)acrylate or n-butyl (meth)acrylate or ethyl (meth)acrylate or isobutyl (meth)acrylate or propyl (meth)acrylate or lauryl (meth)acrylate; the (meth)acrylic acid functional monomer is a group having polar groups such as -COOH, -OH, amide groups, or groups that can participate in post-curing reactions such as unsaturated double bonds; the (meth)acrylic acid functional monomer includes but is not limited to hydroxyethyl (meth)acrylate or hydroxybutyl (meth)acrylate or acrylamide or N-vinyl caprolactam or acrylonitrile or N-vinyl pyrrolidone or (meth)acrylic acid or 2-carboxyethyl acrylate or 4-hydroxyvinyloxybenzophenone methacrylate.

[0025] A method for preparing a multi-layer folded OCA, the specific steps are as follows:

[0026] Step 1: Preparation of acrylic elastomer layer

[0027] S1, under nitrogen protection, acrylic soft monomer, acrylic functional monomer and light emitting agent are added into a reaction kettle according to weight, UV irradiated, and the reaction conversion rate is controlled to be 5-15% to obtain acrylic elastomer prepolymer;

[0028] S2, after uniformly mixing the acrylic elastomer prepolymer, acrylic functional monomer and free radical initiator, coating the mixture on a release film with a release force of 5-10 gf / 25 mm, and UV curing the mixture under a nitrogen atmosphere to obtain an acrylic elastomer layer;

[0029] Step 2: Preparation of acrylic pressure-sensitive adhesive layer

[0030] S1, under nitrogen protection, acrylic soft monomer, acrylic functional monomer, ethyl acetate and free radical initiator are added into a reaction kettle according to weight parts, and the reaction kettle is kept at 65° C. for 8 hours to obtain an acrylic pressure-sensitive adhesive prepolymer;

[0031] S2, mixing the acrylic pressure-sensitive adhesive prepolymer, ethyl acetate, a cross-linking agent and a silane coupling agent uniformly, coating the mixture on a release film with a release force of 15-20 gf / 25 mm, and drying the mixture to obtain an acrylic pressure-sensitive adhesive layer;

[0032] Step three, lamination, placing the acrylic elastomer layer between two acrylic pressure-sensitive adhesive layers, compounding through a laminating device, and aging to obtain a multi-layer folded OCA.

[0033] Since the present invention adopts the above technical solution, the present invention has the following advantages and positive effects:

[0034] 1. Successfully solved the performance contradiction that single-layer OCA could not take into account, so that folding devices can still maintain good flexibility at low temperatures, effectively reducing the problems of increased modulus and brittleness caused by low temperatures, thereby reducing the risk of creases;

[0035] 2. High adhesion ensures a strong bond between OCA and display components, greatly improving the reliability and stability of the device and reducing the possibility of display failure and component falling off due to weak bonding;

[0036] 3. The characteristics of high creep and low recovery enable OCA to effectively absorb and disperse stress during the folding process, significantly reducing the formation and deepening of creases and extending the service life of the folding equipment;

[0037] 4. Good recovery performance enables the folding device to quickly return to a flat state after use, maintaining the aesthetic appearance and consistency of display effects;

[0038] 5. This innovative structural design provides strong support for the further development of foldable display technology and enhances the product's market competitiveness and user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the structure of a multi-layer folded OCA.

[0040] Figure 2 It is a schematic diagram of the bending test structure.

[0041] In the figure, 1 is an acrylic elastomer layer, and 2 is an acrylic pressure-sensitive adhesive layer. DETAILED DESCRIPTION

[0042] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0043] A method for preparing a multi-layer folded OCA, the specific steps are as follows:

[0044] Step 1: Preparation of acrylic elastomer layer

[0045] S1, under nitrogen protection, acrylic soft monomer, acrylic functional monomer and light emitting agent are added into a reaction kettle according to weight, UV irradiated, and the reaction conversion rate is controlled to be 5-15% to obtain acrylic elastomer prepolymer;

[0046] S2, after uniformly mixing the acrylic elastomer prepolymer, acrylic functional monomer and free radical initiator, coating the mixture on a release film with a release force of 5-10 gf / 25 mm, and UV curing the mixture under a nitrogen atmosphere to obtain an acrylic elastomer layer;

[0047] Step 2: Preparation of acrylic pressure-sensitive adhesive layer

[0048] S1, under nitrogen protection, acrylic soft monomer, acrylic functional monomer, ethyl acetate and free radical initiator are added into a reaction kettle according to weight parts, and the reaction kettle is kept at 65° C. for 8 hours to obtain an acrylic pressure-sensitive adhesive prepolymer;

[0049] S2, mixing the acrylic pressure-sensitive adhesive prepolymer, ethyl acetate, a cross-linking agent and a silane coupling agent uniformly, coating the mixture on a release film with a release force of 15-20 gf / 25 mm, and drying the mixture to obtain an acrylic pressure-sensitive adhesive layer;

[0050] Step 3: Lamination: placing the acrylic elastomer layer between two acrylic pressure-sensitive adhesive layers, compounding and aging the layers through a laminating device to obtain a multi-layer folded OCA. Figure 1 shown.

[0051] 2-EHA is 2-ethylhexyl acrylate purchased from LG Chemical

[0052] AA is acrylic acid purchased from Formosa Plastics

[0053] BA is butyl acrylate purchased from Satellite Petrochemical

[0054] HBA was purchased from Osaka Organic

[0055] LA is dodecyl acrylate purchased from Sartomer Chemical

[0056] nDDm is n-dodecyl mercaptan purchased from BASF

[0057] TMPTA is trimethylolpropane triacrylate purchased from Aladdin Reagents

[0058] KBM403 is 3-(2,3-epoxypropoxy)propyltrimethoxysilane purchased from Ziyue Chemical

[0059] TPO is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide purchased from BASF

[0060] 184 is 1-hydroxycyclohexyl phenyl ketone purchased from BASF

[0061] HDDA is 1,6-hexanediol diacrylate purchased from Sigma Chemical

[0062] The weight parts of the components in Examples 1-6 and Comparative Examples 1-3 are shown in Table 1

[0063]

[0064] Table 1

[0065] OCA tape evaluation

[0066] 180 degree peel strength test on glass plate: ASTM D3330

[0067] Storage modulus, loss modulus, tanδ: TA Hybrid Rheometer DHR-2, ASTM D4440-15

[0068] Glass transition temperature: Differential scanning calorimeter TA Q2000, test standard GB / T 19466.2-2004.

[0069] Dynamic bending test: radius 3mm, 30 times / min, 300,000 times, structure as Figure 2 Shown

[0070] Static bending test: radius 3mm, room temperature 500 hours, structure as Figure 2 Shown

[0071] Performance Test of Examples 1-6 and Comparative Examples 1-3

[0072]

[0073] Table 2

[0074] As can be seen from Table 2, the present invention successfully solves the performance contradiction that a single-layer OCA cannot take into account, so that the folding device can still maintain good flexibility at low temperatures, effectively reducing the problems of increased modulus and increased brittleness caused by low temperatures, thereby reducing the risk of creases; high adhesion ensures a firm bond between the OCA and the display component, greatly improving the reliability and stability of the device, and reducing the possibility of display failures and component detachment due to loose bonding.

[0075] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A multi-layer folding OCA, characterized by: The multi-layer folded OCA comprises the following components in parts by weight: Acrylic resin 97-99 parts Crosslinking agent 0.1-1 part Silane coupling agent 0.1-0.5 parts Free radical initiator 0.05-1 part; The multi-layer folded OCA is a sandwich structure.

2. The multi-layer folded OCA according to claim 1, characterized in that: The multi-layer folded OCA comprises an acrylic elastomer layer, and the upper and lower sides of the acrylic elastomer layer are respectively connected with acrylic pressure-sensitive adhesive layers.

3. The multi-layer folded OCA according to claim 2, characterized in that: The acrylic pressure-sensitive adhesive layer comprises the following components in parts by weight: Acrylic soft monomer 80-95 parts 5-20 parts of acrylic functional monomer, 0.1-0.5 parts of free radical initiator; The acrylic pressure-sensitive adhesive layer is prepared by polymerization of acrylic soft monomers, acrylic functional monomers and free radical initiators.

4. The multi-layer folded OCA according to claim 2, characterized in that: The molecular weight of the acrylic pressure-sensitive adhesive is 200,000-1,000,000; the thickness of the acrylic pressure-sensitive adhesive is 5-50 um.

5. The multi-layer folded OCA according to claim 4, characterized in that: The molecular weight of the acrylic pressure-sensitive adhesive is 300,000-800,000; the thickness of the acrylic pressure-sensitive adhesive is 5-25 um.

6. The multi-layer folded OCA according to claim 2, characterized in that: The acrylic elastomer layer comprises the following components in parts by weight: Acrylic soft monomer 95-99 parts 1-5 parts of acrylic functional monomer 0.1-0.5 parts of free radical initiator; The acrylic elastomer layer is prepared by polymerizing acrylic soft monomers, acrylic functional monomers and free radical initiators.

7. The multi-layer folded OCA according to claim 6, characterized in that: The molecular weight of the acrylic elastomer is greater than 5 million; the thickness of the acrylic elastomer is 10-100 um.

8. The multi-layer folded OCA according to claim 1, characterized in that: The molecular weight of the acrylic elastomer is 6-8 million; the thickness of the acrylic elastomer is 10-50 um.

9. A multi-layer folded OCA according to any one of claims 3 or 6, characterized in that: The acrylic soft monomer includes but is not limited to 2-ethylhexyl (meth)acrylate or n-octyl (meth)acrylate or n-decyl (meth)acrylate or n-butyl (meth)acrylate or ethyl (meth)acrylate or isobutyl (meth)acrylate or propyl (meth)acrylate or lauryl (meth)acrylate; the acrylic functional monomer includes but is not limited to hydroxyethyl (meth)acrylate or hydroxybutyl (meth)acrylate or acrylamide or N-vinyl caprolactam or acrylonitrile or N-vinyl pyrrolidone or (meth)acrylic acid or 2-carboxyethyl acrylate or 4-hydroxyvinyloxybenzophenone methacrylate.

10. A method for preparing a multi-layer folded OCA according to any one of claims 1 to 9, characterized in that: Specific steps as follows: Step 1: Preparation of acrylic elastomer layer S1, under nitrogen protection, acrylic soft monomer, acrylic functional monomer and light emitting agent are added into a reaction kettle according to weight, UV irradiated, and the reaction conversion rate is controlled to be 5-15% to obtain acrylic elastomer prepolymer; S2, after uniformly mixing the acrylic elastomer prepolymer, acrylic functional monomer and free radical initiator, coating the mixture on a release film with a release force of 5-10 gf / 25 mm, and UV curing the mixture under a nitrogen atmosphere to obtain an acrylic elastomer layer; Step 2: Preparation of acrylic pressure-sensitive adhesive layer S1, under nitrogen protection, acrylic soft monomer, acrylic functional monomer, ethyl acetate and free radical initiator are added into a reaction kettle according to weight parts, and the reaction kettle is kept at 65° C. for 8 hours to obtain an acrylic pressure-sensitive adhesive prepolymer; S2, mixing the acrylic pressure-sensitive adhesive prepolymer, ethyl acetate, a cross-linking agent and a silane coupling agent uniformly, coating the mixture on a release film with a release force of 15-20 gf / 25 mm, and drying the mixture to obtain an acrylic pressure-sensitive adhesive layer; Step three, lamination, placing the acrylic elastomer layer between two acrylic pressure-sensitive adhesive layers, compounding through a laminating device, and aging to obtain a multi-layer folded OCA.

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