Acrylate pressure-sensitive adhesive capable of being tackified through UV irradiation, preparation method and application

Abstract

The invention discloses an acrylate pressure-sensitive adhesive capable of being tackified through UV irradiation and a preparation method and application of the acrylate pressure-sensitive adhesive, and belongs to the technical field of pressure-sensitive adhesives. The pressure-sensitive adhesive is composed of functional monomer o-nitrobenzyl (meth) acrylate, (meth) acrylate monomer and other components according to a specific mass ratio. The preparation method comprises the following steps: dropwise adding a mixture of an initiator and a solvent step by step, and carrying out temperature-controlled dark reaction. The core advantages are that the bonding force is switched according to needs: the initial stripping force is low, so that the alignment adjustment during the bonding of precise electronic components is facilitated, and the damage to a base material is avoided; after UV irradiation, the functional monomer is subjected to photolysis to generate polar groups, the stripping force is increased to 100 times or more of the initial value, strong bonding is achieved, and the pressure-sensitive adhesive is easy and convenient to operate, stable in performance, suitable for manufacturing of electronic components such as semiconductors and display modules and capable of meeting the stable bonding requirements of subsequent procedures such as grinding and cutting.

Description

Technical Field

[0001] This invention relates to the field of pressure-sensitive adhesive technology, specifically to an acrylic pressure-sensitive adhesive that can be tackified by UV irradiation, its preparation method, and its application. Background Technology

[0002] In the manufacturing process of electronic components such as semiconductors, display modules, and flexible circuit boards, protective films, fixing tapes, or temporary bonding adhesives are often required. These applications typically face a contradictory requirement: during the bonding and alignment stages, the tapes need to have low peel strength, be easy to move and adjust, and avoid damaging precision components; while in subsequent grinding, cutting, transportation, or packaging processes, the tapes need to have high adhesive strength to ensure that the components are in a stable position and do not shift or fall off.

[0003] Traditional pressure-sensitive adhesives struggle to simultaneously meet these two opposing needs. Common solutions involve using tapes with varying viscosities in stages, or using pressure-sensitive tapes, but these methods suffer from complex processes, poor positioning accuracy, or insufficient reliability. Therefore, developing a smart pressure-sensitive adhesive with controllable viscosity switching is of great significance.

[0004] Photoresponsive adhesives are one effective way to solve this problem. In the prior art, some photo-crosslinking or photodegrading adhesives have been reported, but they often suffer from problems such as decreased tackiness after light exposure (making peeling easier) or the need for complex photoinitiator systems. This invention aims to provide a pressure-sensitive adhesive that is simple to synthesize, has controllable performance, and exhibits significant effects with reversible or unidirectional tack enhancement after UV irradiation. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] Therefore, the purpose of this invention is to provide a UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive, its preparation method, and its application, in order to solve the problems mentioned in the background art.

[0007] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0008] A UV-curable acrylate pressure-sensitive adhesive, comprising the following components by mass ratio: 5-25 parts functional monomer; 60-80 parts (meth)acrylate monomer; 1-10 parts carboxyl monomer; 1-10 parts hydroxyl monomer; 1-5 parts vinyl acetate; 120-180 parts solvent; and 0.1-1 parts initiator.

[0009] The functional monomer is o-nitrobenzyl (meth)acrylate, which is prepared by esterification of 1-1.1 parts of (meth)acrylate and 1 part of o-nitrobenzyl alcohol in the presence of a catalyst and a polymerization inhibitor.

[0010] As a preferred embodiment of the UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive of the present invention, the (meth)acrylate monomer is one or both of isooctyl acrylate (EHA) and butyl acrylate (BA).

[0011] As a preferred embodiment of the UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive of the present invention, the carboxyl monomer is one or both of acrylic acid (AA) and β-acryloyloxypropionic acid (β-CEA).

[0012] As a preferred embodiment of the UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive of the present invention, the hydroxyl monomer is hydroxyethyl acrylate (HEA).

[0013] As a preferred embodiment of the UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive of the present invention, the solvent is one or both of ethyl acetate (EAc) and toluene (ToL).

[0014] As a preferred embodiment of the UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive of the present invention, the initiator is benzoyl peroxide (BPO).

[0015] A method for preparing a UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive, comprising the following steps:

[0016] S1. Add 5-25 parts of functional monomer, 60-90 parts of (meth)acrylate monomer, 1-10 parts of carboxyl monomer, 1-10 parts of hydroxyl monomer, 1-5 parts of vinyl acetate (VAc), and 70-100 parts of solvent to the reaction flask, and heat to 80℃.

[0017] S2. Begin adding a mixture of 0.1-0.5 parts initiator and 20-40 parts solvent dropwise, completing the addition in 120 minutes; after the addition is complete, keep the mixture warm for 60 minutes, then continue adding another 0.1-0.5 parts initiator and 20-40 parts solvent dropwise, completing the addition in 90 minutes.

[0018] S3. After keeping warm for 120 minutes, add 30-50 parts of solvent, cool down and discharge the material. Maintain the temperature at 85-90℃ during the reaction and avoid light.

[0019] An application of a UV-irradiated tack-enhancing acrylate is as follows: The synthesized pressure-sensitive adhesive resin is mixed with a crosslinking agent and a solvent to form an adhesive solution with a certain solid content, which is then coated onto a PET film, PE film or other substrates and dried in an oven to form an adhesive tape.

[0020] When the tape is applied to the surface of the object, the peel force is low, making it easy to align and adjust. After confirming that the position is correct, it is irradiated with a UV light source of specific wavelength and energy. After irradiation, the peel force of the tape is increased, achieving a strong bond.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention first synthesizes a (meth)acrylate functional monomer containing a photosensitive group (o-nitrobenzyl ester), and then introduces it into the main chain of an acrylate copolymer to prepare a pressure-sensitive adhesive with photoresponsive properties. The o-nitrobenzyl ester group undergoes a photolysis reaction under UV irradiation to generate o-nitrosobenzaldehyde (or further reaction) and (meth)acrylate. The newly generated carboxylic acid group is highly polar and can form stronger van der Waals forces, hydrogen bonds, and even chemical bonds with the surface of the substrate. At the same time, the removed o-nitrosobenzaldehyde also provides good polarity and exists in the adhesive layer as a small molecule tackifier, thus macroscopically manifesting as a significant increase in peel strength. This allows for on-demand switching of low to high adhesive strength, perfectly matching the multi-step process requirements of precision electronic assembly.

[0023] 2. Only one UV irradiation step is needed to trigger adhesion, without the need to change the tape or add other chemicals. It is easy to integrate into automated production lines, simple to operate, and highly efficient. In addition, the low initial tack avoids the risk of damage to fragile substrates such as wafers, glass, and flexible circuits during adjustment. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 These are performance test diagrams of the UV-irradiated tack-enhancing acrylic pressure-sensitive adhesives prepared in Examples 1-5 of this invention. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Example 1

[0028] Add 10 parts of o-nitrobenzyl acrylate, 80 parts of isooctyl acrylate (EHA), 1.5 parts of acrylic acid (AA), 3 parts of hydroxyethyl acrylate (HEA), 3 parts of vinyl acetate (VAc), and 90 parts of ethyl acetate (EAc) to the reaction flask. Heat to 80°C, and begin adding dropwise a mixture of 0.2 parts of benzoyl peroxide (BPO) and 20 parts of toluene (ToL), completing the addition over 120 minutes. After the addition is complete, maintain the temperature for 60 minutes, and then continue adding a mixture of 0.2 parts of initiator and 20 parts of toluene (ToL), completing the addition over 90 minutes. After maintaining the temperature for 120 minutes, add 50 parts of solvent, cool, and discharge the product. Maintain the temperature at 85-90°C and protect from light during the reaction.

[0029] Example 2

[0030] Add 5 parts of o-nitrobenzyl acrylate, 60 parts of isooctyl acrylate (EHA), 25 parts of butyl acrylate (BA), 1.5 parts of acrylic acid (AA), 3 parts of hydroxyethyl acrylate (HEA), 3 parts of vinyl acetate (VAc), and 90 parts of ethyl acetate (EAc) to the reaction flask. Heat to 80°C, and begin adding dropwise a mixture of 0.2 parts of benzoyl peroxide (BPO) and 20 parts of toluene (ToL), completing the addition over 120 minutes. After the addition is complete, maintain the temperature for 60 minutes, and then continue adding a mixture of 0.2 parts of initiator and 20 parts of toluene (ToL), completing the addition over 90 minutes. After maintaining the temperature for 120 minutes, add 50 parts of solvent to cool and discharge the product. Maintain the temperature at 85-90°C and protect from light during the reaction.

[0031] Example 3

[0032] Add 10 parts of o-nitrobenzyl acrylate, 80 parts of isooctyl acrylate (EHA), 1.5 parts of β-acryloyloxypropionic acid (β-CEA), 3 parts of hydroxyethyl acrylate (HEA), 3 parts of vinyl acetate (VAc), and 90 parts of ethyl acetate (EAc) to the reaction flask. Heat to 80°C, and begin dropwise adding a mixture of 0.2 parts of benzoyl peroxide (BPO) and 20 parts of toluene (ToL), completing the addition over 120 minutes. After the addition is complete, maintain the temperature for 60 minutes, and then continue adding a mixture of 0.2 parts of initiator and 20 parts of toluene (ToL), completing the addition over 90 minutes. After maintaining the temperature for 120 minutes, add 50 parts of solvent, cool, and discharge the product. Maintain the temperature at 85-90°C and protect from light during the reaction.

[0033] Example 4

[0034] Add 8 parts of o-nitrobenzyl acrylate, 70 parts of isooctyl acrylate (EHA), 15 parts of butyl acrylate (BA), 1.5 parts of acrylic acid (AA), 3 parts of hydroxyethyl acrylate (HEA), 3 parts of vinyl acetate (VAc), and 90 parts of ethyl acetate (EAc) to the reaction flask. Heat to 80°C, and begin adding dropwise a mixture of 0.2 parts of benzoyl peroxide (BPO) and 20 parts of toluene (ToL), completing the addition over 120 minutes. After the addition is complete, maintain the temperature for 60 minutes, and then continue adding a mixture of 0.2 parts of initiator and 20 parts of toluene (ToL), completing the addition over 90 minutes. After maintaining the temperature for 120 minutes, add 50 parts of solvent to cool and discharge the product. Maintain the temperature at 85-90°C and protect from light during the reaction.

[0035] Example 5

[0036] Add 10 parts of o-nitrobenzyl acrylate, 80 parts of isooctyl acrylate (EHA), 1.5 parts of acrylic acid (AA), 3 parts of hydroxyethyl acrylate (HEA), 3 parts of vinyl acetate (VAc), 75 parts of ethyl acetate (EAc), and 15 parts of toluene (ToL) to the reaction flask. Heat to 80°C, and begin adding dropwise a mixture of 0.2 parts of benzoyl peroxide (BPO) and 20 parts of toluene (ToL), completing the addition over 120 minutes. After the addition is complete, maintain the temperature for 60 minutes, and then continue adding a mixture of 0.2 parts of initiator and 20 parts of toluene (ToL), completing the addition over 90 minutes. After maintaining the temperature for 120 minutes, add 50 parts of solvent, cool, and discharge the product. Maintain the temperature at 85-90°C and protect from light during the reaction.

[0037] The UV-irradiated tack-enhancing acrylic pressure-sensitive adhesives prepared in Examples 1-5 exhibit the following properties: Figure 1 As shown:

[0038] Before UV peel force: The initial peel force of all embodiments is low (9.12-10.66 gf / inch), which meets the process requirements of easy alignment and adjustability, and avoids damage to precision parts. After UV peel force: The peel force after irradiation increases significantly (1120-1377 gf / inch), which is more than 100 times the initial value, achieving the technical effect of strong adhesion.

[0039] UV holding power (85℃, 2h): It can maintain basic bonding stability in high temperature environment in the initial state and does not fall off; UV peel strength: UV holding power (85℃, 2h): After the adhesion is increased, it can still be firmly bonded under high temperature conditions, meeting the requirements of subsequent grinding, cutting, transportation and other processes.

[0040] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive, characterized in that, The composition by mass ratio is as follows: 5-25 parts of functional monomer; 60-80 parts of (meth)acrylate monomer; 1-10 parts of carboxyl monomer; 1-10 parts of hydroxyl monomer; 1-5 parts of vinyl acetate; 120-180 parts of solvent; and 0.1-1 parts of initiator. The functional monomer is o-nitrobenzyl (meth)acrylate, which is prepared by esterification of 1-1.1 parts of (meth)acrylate and 1 part of o-nitrobenzyl alcohol in the presence of a catalyst and a polymerization inhibitor.

2. The UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The (meth)acrylate monomer is one or both of isooctyl acrylate and butyl acrylate.

3. The UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The carboxyl monomer is one or both of acrylic acid and β-acryloyloxypropionic acid.

4. The UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The hydroxy monomer is hydroxyethyl acrylate.

5. The UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The solvent is one or both of ethyl acetate and toluene.

6. The UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The initiator is benzoyl peroxide.

7. A method for preparing a UV-irradiated tack-enhancing acrylic pressure-sensitive adhesive as described in any one of claims 1-6, characterized in that, The steps are as follows: S1. Add 5-25 parts of functional monomer, 60-90 parts of (meth)acrylate monomer, 1-10 parts of carboxyl monomer, 1-10 parts of hydroxyl monomer, 1-5 parts of vinyl acetate, and 70-100 parts of solvent to the reaction flask, and heat to 80℃. S2. Begin adding a mixture of 0.1-0.5 parts initiator and 20-40 parts solvent dropwise, completing the addition in 120 minutes; after the addition is complete, keep the mixture warm for 60 minutes, then continue adding another 0.1-0.5 parts initiator and 20-40 parts solvent dropwise, completing the addition in 90 minutes. S3. After keeping warm for 120 minutes, add 30-50 parts of solvent, cool down and discharge the material. Maintain the temperature at 85-90℃ during the reaction and avoid light.

8. An application of a UV-irradiated tackifying acrylate as described in any one of claims 1-6, characterized in that, Specifically, the synthesized pressure-sensitive adhesive resin is mixed with a crosslinking agent and solvent to form an adhesive solution with a certain solid content, which is then coated onto PET film, PE film or other substrates and dried in an oven to form an adhesive tape. When the tape is applied to the surface of the object, the peel force is low, making it easy to align and adjust. After confirming that the position is correct, it is irradiated with a UV light source of specific wavelength and energy. After irradiation, the peel force of the tape is increased, achieving a strong bond.

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