Optical adhesive

Abstract

The application discloses an optical adhesive suitable for adhering plastic plates (such as PC and PMMA), and the optical adhesive has good adhesion and optical performance, and can inhibit the appearance of bubble, white edge and other appearance defects in a high-temperature and high-humidity environment. In addition, the optical adhesive is prepared by using a UV polymerization method, and the optical adhesive is prepared by carrying out bulk polymerization through photo-initiation, so that the optical adhesive has the advantages of improved production capacity and environmental protection.

Description

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 getting higher and higher, 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 transparent double-sided tape without substrate, optical adhesive can be used to bond 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 prepared by UV bulk polymerization for bonding 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 (meth) 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] 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.

[0010] wherein the (meth)acrylate containing aromatic group includes one or more of phenylbenzyl acrylate, phenoxaprofen (meth)acrylate, monoethoxyphenylphenoxy (meth)acrylate, and poly(ethoxy)phenylphenoxy (meth)acrylate.

[0011] In the present application, UV bulk polymerization is used to prepare the base polymer. In the polymerization, a corresponding photoinitiator can be selected according to 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 actual needs.

[0012] The second aspect of the present application provides an optical double-sided adhesive sheet comprising the optical adhesive provided by the first aspect of the present application, and having an adhesive layer on one side or both sides of a substrate. The thickness of the substrate is 50 μm or more.

[0013] The present application provides an optical double-sided adhesive sheet, which can be used in full lamination technology and used to fill air gaps in vehicle-mounted optical products.

[0014] Compared with the prior art, the present application has the following advantages:

[0015] 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 means and bulk polymerization by photoinitiation, which has the advantages of improving production capacity and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A schematic diagram of the optical adhesive provided by the present application. DETAILED DESCRIPTION

[0017] 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.

[0018] Table 1 Optical adhesive implementation

[0019]

[0020] The adhesive composition was prepared by adding the multifunctional monomer (1,6-hexanediol diacrylate, HDDA) and the silane coupling agent (MOMENTIVE, "Silquest A-187") in the amounts shown in Table 1 as post-adding ingredients to the prepolymer composition shown in Table 1, and then uniformly mixing.

[0021] The optical adhesive obtained by adhering the plastic substrate in the above Examples 1-3 and Comparative Examples 1-2 was mixed with the desired crosslinking agent and silane coupling agent, and was coated on a 75-um PET release film at a thickness of 200 um, and was cured by UV to obtain the corresponding optical adhesive, the structure of which is shown in Figure 1

[0022] Performance test

[0023] The optical adhesive prepared in the above Examples 1-3 and Comparative Examples 1-2 was adhered to a plastic substrate (e.g., PC) to obtain an adhesive sheet using a vacuum adhering method, the peel strength and optical performance of the adhesive sheet were measured, and the adhesive sheet was subjected to a double "85" environment test to observe whether bubbles were generated during the test, and the results are shown in Table 2.

[0024] Table 2: Results of different performance tests

[0025]

[0026] From the above test results, it can be seen that, compared with Comparative Example 1-2, the optical adhesive for adhering plastic substrates (e.g., PC) of the present application Examples 1-3 is not prone to generating 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 adhering plastic substrates.

[0027] The above examples are only for illustrating the technical concept and characteristics of the present application, 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 for PC plastic substrates, comprising an acrylic adhesive layer composed of an acrylic polymer, a multifunctional monomer 1,6-hexanediol diacrylate, and a silane coupling agent Silquest A-187, characterized in that, The acrylic polymer is composed of butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, 3-phenoxybenzyl acrylate and benzoin dimethyl ether, wherein the amount of 3-phenoxybenzyl acrylate in the acrylic polymer is 0.1-15 wt%.

2. An optical double-sided adhesive sheet having an adhesive layer on both sides of a substrate as described in claim 1 for an optical adhesive for a PC plastic substrate.

3. The optical double-sided adhesive sheet as described in claim 2, characterized in that, The thickness of the substrate is at least 50 μm.

4. The use of an optical double-sided adhesive sheet as described in any one of claims 2-3 in full lamination technology, and / or in filling air gaps in automotive optical products.

5. An automotive optical product comprising an optical adhesive for a PC plastic substrate as described in claim 1, and / or an optical double-sided adhesive sheet as described in any one of claims 2-3.

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