OCA optical adhesive tape

Abstract

The invention discloses an OCA (Optical Clear Adhesive) tape which comprises a light release film, a pressure-sensitive adhesive layer and a heavy release film, and the pressure-sensitive adhesive layer comprises the following raw materials in parts by weight: 80-95 parts of (methyl) acrylic resin prepolymer, 5-15 parts of carbon nanotubes, 0.1-1 part of a curing agent and 0.05-0.5 part of a photoinitiator. The adhesive tape product disclosed by the invention has the advantages of static electricity resistance, high cohesiveness and the like, and can effectively reduce the color difference between a display part and an edge part, so that a screen achieves an integrated black effect, the static aesthetic feeling of a display is greatly improved, the quality of display equipment is improved from the appearance, and better experience is brought to consumers.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to an OCA optical adhesive tape. Background Art

[0002] As the development of intelligent display devices accelerates, screen displays are developing towards large size, multi-screen, high-definition, interactive, and multi-format, and higher requirements are placed on display performance, including high contrast, low reflectivity, wide viewing angle, high brightness, touch, and fast response, etc. In addition, the novel design of display details and structures can also play an unexpected role in improving product competitiveness. Therefore, the "one-piece black" technology that can create a novel, eye-catching, beautiful, and technological display effect will become one of the trends.

[0003] In addition, for the image display device, static electricity is generated during its manufacture (for example, when the optical laminate is attached to the image display unit via an adhesive sheet) or during use (for example, when the user touches the image display device). If the image display device is charged due to the static electricity, problems such as poor display may occur. In an environment where static electricity is particularly prone to occur, such as the interior of a vehicle where other electronic devices are present around, in order to fully prevent the poor display caused by the charging of the image display device, it is considered to adjust the surface resistance value of the adhesive sheet to a low value by adding a conductive agent to the adhesive composition. However, in the case of excessively increasing the amount of the conductive agent, in the case of a high temperature environment such as the interior of a vehicle after summer, there is a tendency for the optical properties to be reduced and the durability of the adhesive sheet to be reduced due to the precipitation of the conductive agent.

[0004] For the above requirements, the OCA on the market can only meet one of them, or meet both of the above requirements at the expense of the performance of the pressure-sensitive adhesive. How to find a composite material that can meet both of the above requirements has become a difficult problem that we need to solve.

[0005] Therefore, in view of the above technical problems, it is necessary to provide an OCA optical tape.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide an OCA optical adhesive tape.

[0008] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0009] The OCA optical adhesive tape comprises a light release film, a pressure-sensitive adhesive layer and a heavy release film, wherein the raw materials of the pressure-sensitive adhesive layer include, by weight: 80-95 parts of (methyl) acrylic resin prepolymer, 5-15 parts of carbon nanotubes, 0.1-1 parts of curing agent, and 0.05-0.5 parts of photoinitiator.

[0010] In one or more embodiments of the present invention, the carbon nanotubes meet the following requirements: carbon content>85%, CNT content≥80%, single-layer structure, outer diameter 1.4-2.2nm, length>5μm, and metal impurities<15wt%. The preferred carbon nanotubes in this solution have the advantages of high strength, excellent electrical conductivity, and large specific surface area.

[0011] In one or more embodiments of the present invention, the curing agent is an active material containing two or more photoactive (meth)acrylate functional groups.

[0012] In one or more embodiments of the present invention, the curing agent is selected from 1,6-hexanediol diacrylate HDDA, dipropylene glycol diacrylate DPGDA, tripropylene glycol diacrylate TPGDA, and trimethylolpropane triacrylate TMPTA.

[0013] In one or more embodiments of the present invention, the (meth)acrylic resin prepolymer is polymerized by 60-80 parts of (meth)acrylate soft monomer, 15-30 parts of (meth)acrylic hard monomer, 1-10 parts of (meth)acrylic functional monomer, and 0.05-0.5 parts of photoinitiator, by weight.

[0014] In one or more embodiments of the present invention, the (meth)acrylic soft monomer is selected from: 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-butyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, propyl (meth)acrylate, lauryl (meth)acrylate, and 4-hydroxybutyl acrylate.

[0015] In one or more embodiments of the present invention, the (meth)acrylic hard monomer is selected from: methyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate.

[0016] In one or more embodiments of the present invention, the (meth)acrylic functional monomer is a monomer having a polar group or an unsaturated double bond group that can participate in the post-curing reaction, and the polar group is selected from -COOH, -OH, and amide.

[0017] In one or more embodiments of the present invention, the (meth)acrylic functional monomer is selected from hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, acrylamide, N-vinyl caprolactam, acrylonitrile, N-vinyl pyrrolidone, (meth)acrylic acid, 2-carboxyethyl acrylate, 4-hydroxyvinyloxybenzophenone methacrylate, and N,N-dimethylacetoacetamide.

[0018] In one or more embodiments of the present invention, the monomer conversion rate of the (meth)acrylic resin prepolymer is in the range of 10-20%.

[0019] In one or more embodiments of the present invention, the photoinitiator is photoinitiator 184 .

[0020] Compared with the prior art, the OCA optical adhesive tape of the present invention, by introducing carbon nanotubes, can achieve a volume resistivity of less than 10^8, a transmittance of 10-30%, and a chromaticity difference △E≤1.5. It is used for bonding screens of mobile phones, tablets, car displays, etc., and can provide excellent antistatic performance and an integrated black screen effect. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0022] Test Method

[0023] 180° peel adhesion test: Test conditions: temperature 23°C, humidity 65% ​​RH; test substrate SUS A plate; sample width 25mm; speed 300mm / min; test standard ASTM D3330

[0024] Optical performance: Konica Minolta colorimetric system, specification model CM-36dG

[0025] Dynamic Thermomechanical Analysis: Anton Paar Rheometer MCR 102e, test standard ASTM D4440-15

[0026] Molecular weight and molecular weight distribution: Gel permeation chromatograph Agilent 1260Infinity, test standard GB / T21863-2008

[0027] Glass transition temperature: Differential scanning calorimeter TA Q2000, test standard GB / T 19466.2-2004

[0028] Example 1

[0029] Preparation of acrylic adhesive prepolymer: In a 2L glass reaction device with nitrogen atmosphere, thermometer and stirring, add 75 parts of BA, 15 parts of MMA, 5 parts of HEA, 5 parts of DMAA, and 0.2 parts of 184, and polymerize by ultraviolet radiation to control the monomer conversion rate at about 15%.

[0030] Preparation of OCA optical tape: Take 100g of the prepared acrylic adhesive prepolymer, add 0.3 parts by mass of 184, 10 parts by mass of carbon nanotubes and 0.1 parts by mass of HDDA respectively, stir for 20 minutes, and then vacuum degas. Apply the prepared acrylic adhesive between two release films, control the adhesive thickness to 50-55μm, and then place it in a UV light box for curing to obtain an OCA optical tape.

[0031] The difference between the embodiments 2, 3, 4 and 5 and the embodiment 1 is only that

[0032] On the basis of Example 1, BA, MMA, 2-HEA and DMAA were replaced by 2-EHA, IBOA, 4-HBA and AM respectively.

[0033] Embodiment 6, 7

[0034] Based on Example 1, the amount of carbon nanotubes was adjusted to 5 and 15.

[0035] Comparative Example 1

[0036] Based on Example 1, the amount of carbon nanotubes was adjusted to 0 parts.

[0037] The monomers, initiators, solvents, silane coupling agents, antioxidants, and stabilizers used in the above examples and comparative examples are referred to as follows:

[0038] Table 1: English abbreviations and Chinese names of monomers, as well as manufacturers.

[0039]

[0040]

[0041] Table 2: Example and comparative example feeding table

[0042]

[0043] Table 3: Test results of examples and comparative examples

[0044]

[0045]

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0047] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An OCA optical tape, comprising a light release film, a pressure-sensitive adhesive layer, and a heavy release film, wherein the raw materials of the pressure-sensitive adhesive layer include, by weight: 80-95 parts of (meth)acrylic resin prepolymer, 5-15 parts of carbon nanotubes, 0.1-1 parts of curing agent, and 0.05-0.5 parts of photoinitiator.

2. The OCA optical tape according to claim 1, characterized in that: The carbon nanotubes meet the following requirements: carbon content>85%, CNT content≥80%, single-layer structure, outer diameter 1.4-2.2nm, length>5μm, and metal impurities<15wt%.

3. The OCA optical tape according to claim 1, characterized in that: The curing agent is an active substance containing two or more photoactive (meth)acrylate functional groups.

4. The OCA optical tape according to claim 2, characterized in that: The curing agent is selected from 1,6-hexanediol diacrylate HDDA, dipropylene glycol diacrylate DPGDA, tripropylene glycol diacrylate TPGDA, and trimethylolpropane triacrylate TMPTA.

5. The OCA optical tape according to claim 1, characterized in that: The (meth) acrylic resin prepolymer is prepared by polymerization of 60-80 parts of (meth) acrylic acid ester soft monomer, 15-30 parts of (meth) acrylic acid hard monomer, 1-10 parts of (meth) acrylic acid functional monomer and 0.05-0.5 parts of photoinitiator in parts by weight.

6. The OCA optical adhesive tape according to claim 5, characterized in that: The (meth)acrylic soft monomer is selected from: 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-butyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, propyl (meth)acrylate, lauryl (meth)acrylate, and 4-hydroxybutyl acrylate.

7. The OCA optical adhesive tape according to claim 5, characterized in that: The (meth)acrylic hard monomer is selected from: methyl (meth)acrylate, isobornyl (meth)acrylate, and cyclohexyl (meth)acrylate.

8. The OCA optical adhesive tape according to claim 5, characterized in that: The (meth)acrylic functional monomer is a monomer having a polar group or an unsaturated double bond group that can participate in a post-curing reaction, and the polar group is selected from -COOH, -OH, and amide group.

9. The OCA optical adhesive tape according to claim 8, characterized in that: The (meth)acrylic functional monomer is selected from hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, acrylamide, N-vinyl caprolactam, acrylonitrile, N-vinyl pyrrolidone, (meth)acrylic acid, 2-carboxyethyl acrylate, 4-hydroxyvinyloxybenzophenone methacrylate, and N,N-dimethylacetoacetamide.

10. The OCA optical adhesive tape according to claim 1, characterized in that: The monomer conversion rate of the (meth)acrylic resin prepolymer is in the range of 10-20%.

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