Optical adhesive

Abstract

An optical adhesive suitable for laminating plastic sheets (such as PC and PMMA). The optical adhesive has good adhesion and optical properties, and can inhibit the occurrence of defects in the outward appearance such as bubbles and white edges in high-temperature and high-humidity environments. The optical adhesive is prepared by means of UV polymerization; and is subjected to a photo-initiated bulk polymerization process, such that the adhesive has the advantages of an increased production capacity and being environmentally friendly.

Description

Optical adhesive TECHNICAL FIELD

[0001] The present application relates to the field of adhesives, in particular to optical adhesives. BACKGROUND

[0002] In recent years, with the development of science and technology, people's requirements for electronic devices are also increasing, and plastic materials (such as PC, PMMA) are popular materials for electronic devices. Therefore, it is of great market value to develop optical adhesives with good bonding performance, appearance performance and stability for plastic plates. As a kind of transparent double-sided tape without base material, optical adhesive can be used for bonding display components in display. Ordinary optical adhesive has the advantages of high light transmittance, low haze and low b* value.

[0003] Among common plastic plates, PC and PMMA plates have relatively large shrinkage rates and poor wettability with optical adhesives. In addition, PC has water absorption performance in high temperature and high humidity environment, which can absorb water from the environment to the interface bonded with optical adhesives. Therefore, optical adhesives bonded with PC plates are prone to produce bubble defects.

[0004] In the prior art, there are optical adhesives suitable for bonding plastic substrates (such as PC and PMMA), which are prepared by solution polymerization or bulk polymerization of soft and hard monomers, solvents, thermal initiators and photoinitiators. However, the prepared optical adhesives are difficult to maintain stability in high temperature and high humidity environment after bonding with plastic plates, and will appear a series of appearance defects such as bubble rebound and white edge after a period of time. Therefore, it is an urgent problem in the field of optical adhesives to find an optical adhesive that can maintain stable performance and good appearance in high temperature and high humidity environment after bonding with plastic plates. SUMMARY

[0005] The present application aims to provide an optical adhesive, which is prepared by UV bulk polymerization for bonding with PC plates, and the optical adhesive does not appear bubble rebound phenomenon in high temperature and high humidity conditions after being bonded with plastic plates (such as PC and PMMA) by vacuum bonding.

[0006] To solve the above technical problems, the first aspect of the present application provides an optical adhesive:

[0007] An optical adhesive contains an acrylic polymer as a base polymer, and the acrylic polymer is a polymer composed of (methyl) alkyl acrylate and an aromatic compound having the following formula 1 as a monomer component, wherein the sum of the proportions of the compounds having "formula 1" in all monomer components constituting the acrylic polymer is 0.1-20wt%.

[0008]

[0009] Chemical Formula 1

[0010] In the above Chemical Formula 1, X is a single bond, an alkyl group having a carbon number of 1-5, or an oxygen atom; Y is a hydrogen atom or a methyl group, R 1 is an alkyl group having a carbon number of 1-10, a halogen atom, or an aryl group having a carbon number of 6-20, n is an integer of 0-5, and R 2 is an alkyl group having a carbon number of 1-10 or a (poly)alkyloxy group having a carbon number of 1-30.

[0011] Among them, the (meth) acrylate containing aromatic group includes one or more of phenylbenzyl ester acrylate, phenoxybenzamine (meth) acrylate, monoethoxy phenyl phenoxy (meth) acrylate and poly (ethoxy) phenyl phenoxy (meth) acrylate.

[0012] In the present application, UV bulk polymerization is used to prepare the base polymer. In the polymerization, the corresponding photoinitiator can be selected according to the actual needs, and if it is necessary to adjust the molecular weight, a chain transfer agent can also be added to the reaction system. The conversion rate, viscosity and molecular weight of the base polymer are not particularly limited, and can be adjusted according to the actual needs.

[0013] The second aspect of the present application provides an optical double-sided adhesive sheet, which comprises the optical adhesive provided by the first aspect of the present application and has an adhesive layer on one side or both sides of the substrate. The thickness of the substrate is 50 μm or more.

[0014] The present application provides an optical double-sided adhesive sheet, which can be used in full lamination technology and used to fill the air gap in the vehicle optical product.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] The present application provides an optical adhesive suitable for bonding plastic plates (such as PC and PMMA), which has good adhesion and optical performance, and can inhibit the occurrence of appearance defects such as bubbles and white edges in a high temperature and high humidity environment. In addition, the optical adhesive is prepared by using UV polymerization method and bulk polymerization by photoinitiation, which has the advantages of improving production capacity and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a schematic diagram of the optical adhesive provided by the present application. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0019] Table 1 Optical adhesive embodiment

[0020]

[0021] In the prepolymer composition shown in Table 1, a multifunctional monomer (1,6-hexanediol diacrylate HDDA) shown in Table 1 was added as a post-adding component, and then uniformly mixed, thereby preparing an adhesive composition.

[0022] The optical adhesive for bonding plastic substrates obtained in Examples 1-3 and Comparative Examples 1-2 above was mixed with a desired crosslinking agent and a silane coupling agent, and coated on a 75-μm PET release film at a thickness of 200 μm, and then cured by UV to obtain corresponding optical adhesives, the structure of which is shown in FIG. 1.

[0023] Performance test

[0024] The optical adhesives prepared in Examples 1-3 and Comparative Examples 1-2 above were respectively bonded to plastic substrates (e.g., PC) to obtain adhesive sheets using a vacuum bonding method, and the peel strength and optical performance of the adhesive sheets were measured, and the adhesive sheets were subjected to a double "85" environment test to observe whether bubbles were generated during the test, and the results are shown in Table 2.

[0025] Table 2 Different performance test results

[0026]

[0027] From the above test results, it can be seen that, compared with Comparative Example 1-2, the optical adhesive for bonding plastic substrates (e.g., PC) of the present application of Examples 1-3 is not prone to generate bubbles in a high-temperature and high-humidity environment, and the peel strength performance is significantly better than that of Comparative Example 1-2. The above results show that the addition of 3-phenoxybenzyl acrylate has a positive effect on the optical adhesive for bonding plastic substrates.

[0028] 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 to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. An optical adhesive, comprising an acrylic adhesive layer having an acrylic polymer as a base polymer, characterized in that, The acrylic polymer is a polymer composed of (meth) alkyl acrylate and an aromatic compound having the following Chemical Formula 1 as a monomer component, wherein the sum of the proportions of the aromatic compound having "Chemical Formula 1" in all monomer components constituting the acrylic polymer is 0.1-20 wt%, 2. Chemical Formula 1 In the above Chemical Formula 1, X is a single bond, an alkyl group having a carbon number of 1-5, or an oxygen atom; Y is a hydrogen atom or a methyl group, R1 is an alkyl group having a carbon number of 1-10, a halogen atom, or an aryl group having a carbon number of 6-20, n is an integer of 0-5, and R2 is an alkyl group having a carbon number of 1-10 or a (poly)alkyloxy group having a carbon number of 1-30.

3. The optical adhesive of claim 1 wherein the epoxy resin is a diglycidyl ether of bisphenol A. 5 The aromatic compound is one or more of phenylbenzyl ester acrylate, phenoxabenzyl (meth) acrylate, monoethoxylphenylphenoxy (meth) acrylate, and poly(ethoxyl)phenylphenoxy (meth) acrylate.

4. An optical double-sided adhesive sheet having an adhesive layer of the optical adhesive according to any one of claims 1-2 on one or both sides of a substrate.

5. The optical double-coated adhesive sheet according to claim 3, wherein The thickness of the substrate is at least 50 μm.

6. Use of the optical double-sided adhesive sheet according to any one of claims 3-4 in full lamination technology, and / or, filling air gaps in vehicle-mounted optical products.

7. A vehicle-mounted optical product having the optical adhesive according to any one of claims 1-2, and / or, the optical double-sided adhesive sheet according to any one of claims 3-4.

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