Photo-thermal dual-curing damp-heat-resistant adhesive composition

Abstract

The invention discloses a photo-thermal dual-curing adhesive composition with heat and humidity resistance. The composition comprises the following components in parts by weight: 100 parts of a polyfunctional group thiol (sulfydryl) silane coupling agent, 60-100 parts of a compound with a benzene ring structure and more than two allyl ethers or allyl esters, 0.5-5 parts of a photoinitiator and 0.5-5 parts of a thermal initiator, and the adhesive prepared from the composition can be photocured or thermally cured. The thiol compound structure adopted by the invention does not contain ester bonds, and a cured product has elasticity and excellent heat and humidity resistance, and still keeps good bonding strength after high-temperature and high-humidity treatment.

Description

Technical Field

[0001] The invention relates to a UV heat dual-curing adhesive, in particular to a UV heat dual-curing adhesive with good moisture and heat resistance, and belongs to the technical field of adhesives. Background Art

[0002] UV glue is widely used for bonding and potting of electronic components because of its high efficiency, energy saving and environmental protection. However, many electronic components have complex shapes and structures, often with shadow areas or components that are opaque, resulting in poor curing due to UV light exposure. At this time, the adhesive needs to have a second curing mechanism to ensure that the shadow area can also be cured through curing modes such as heating or moisture. UV thermal dual curing is the most common dual curing mode, usually composed of acrylate monomers and oligomers with photoinitiators and thermal initiators (for example: CN102925062A), or alicyclic epoxy resins with cationic photoinitiators and cationic thermal initiators. Both systems can be UV thermal dual cured. Acrylic ester compounds and alicyclic epoxy resins can also form a mixed system, respectively performing free radical photocuring of acrylates and cationic thermal curing of alicyclic epoxy resins (for example: CN102675590A), or vice versa, acrylates perform free radical thermal curing and alicyclic epoxy resins perform cationic photocuring.

[0003] The curing of acrylic adhesives, whether light curing or heat curing, has surface oxygen inhibition, resulting in surface stickiness, which affects product quality and is a difficult problem to solve. Although the cationic curing of alicyclic epoxy resins does not have oxygen inhibition, it will not cure due to the influence of air humidity. At the same time, alicyclic epoxy resins are very brittle and hard, lacking elasticity and toughness, and are prone to stress in cold and hot shock environmental tests, resulting in a decrease in bonding strength. Summary of the invention

[0004] The purpose of the present invention is to provide a multifunctional thiol silane coupling agent with simple process and low cost and a light-heat dual-curing adhesive composition containing the coupling agent, and to achieve UV-heat dual curing by utilizing the click reaction of thiol-double bond.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] In the first aspect, the present invention provides a photothermal dual-curing moisture-heat resistant adhesive composition, which includes, by weight: 100 parts of a multifunctional thiol (mercapto) silane coupling agent, 60 to 100 parts of a compound with a benzene ring structure and two or more allyl ethers or allyl esters, 0.5 to 5 parts of a photoinitiator, and 0.5 to 5 parts of a thermal initiator.

[0007] Preferably, the compound having a benzene ring structure and two or more allyl ethers or allyl esters is selected from diallyl phthalate (DAP) or bisphenol A diallyl ether:

[0008]

[0009] Molecular formula-1(DAP)

[0010]

[0011] Molecular formula-2 (bisphenol A bisallyl ether).

[0012] Preferably, the photoinitiator is selected from any one or more of benzoin and its derivatives, benzil derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-aminoalkyl phenone, acylphosphorus oxide, benzophenone and its derivatives, thioxanthone compounds, anthraquinone compounds, fluorenone compounds, etc., preferably α-hydroxyalkyl phenone, acylphosphorus oxide, benzophenone and its derivatives.

[0013] Preferably, the thermal initiator is an azo or peroxide free radical thermal initiator with a decomposition temperature of 60 to 100° C., preferably any one of azobisisobutyronitrile, azobisisoheptanenitrile, lauroyl peroxide, and benzoyl peroxide.

[0014] Preferably, the multifunctional thiol (mercapto) silane coupling agent has the following structure:

[0015]

[0016] Wherein, R represents a methyl group or a methoxy group, and n is an integer of 0 to 100.

[0017] Preferably, the multifunctional thiol (mercapto) silane coupling agent is synthesized by hydrolysis of mercaptopropylmethyldimethoxysilane coupling agent and / or mercaptopropyltrimethoxysilane coupling agent in the presence of a catalyst.

[0018] Specifically, the catalyst is selected from any one or more of inorganic acids, organic acids, organotin compounds, cation exchange resins, titanate compounds, α-silane coupling agents, Lewis acids or Lewis base compounds, preferably any one or more of inorganic acids, organic acids and organotin compounds; the weight ratio of mercaptopropylmethyldimethoxysilane coupling agent and / or mercaptopropyltrimethoxysilane coupling agent to the catalyst is 100:0.05~2.

[0019] More specifically, the inorganic acid and the organic acid are hydrochloric acid, sulfuric acid, phosphoric acid, methanesulfonic acid, trifluoromethanesulfonic acid, toluenesulfonic acid and the like.

[0020] More specifically, the organotin compound is dibutyltin dibutyl ketoxime silicon, dibutyltin diacetylacetonate, dibutyltin diacetylacetate, dibutyltin dilaurate, dibutyltin bistriethoxysilicate, dioctyltin bistriethoxysilicate, and a tetravalent tin compound which is a reaction product of diketoxime tin oxide and a silicate compound.

[0021] Preferably, the adhesive composition may also contain a silane coupling agent, including but not limited to: one or more of γ-methacryloxypropyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, anilinemethyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-ureapropyltriethoxysilane.

[0022] Preferably, the adhesive composition may also contain various fillers, including but not limited to: one or more of fused silica, glass fiber powder, and glass microspheres.

[0023] Preferably, the adhesive composition may also include free radical inhibitors, antioxidants, flame retardants, diluents, adhesion promoters, dyes, pigments, defoamers, leveling agents, etc., which are well known to those skilled in the art and will not be elaborated here.

[0024] In a second aspect, the present invention provides a light-heat dual-curing moisture-heat resistant adhesive, which is obtained by uniformly mixing the adhesive composition described in the first aspect through vacuum stirring.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] (1) No obvious oxygen inhibition was found in the surface curing of the UV-heat dual-curing adhesive of the present invention, whether it was light-cured or heat-cured alone.

[0027] (2) The UV heat dual-curing adhesive of the present invention has excellent moisture and heat resistance, and after high temperature and high humidity tests, the original bonding strength is still maintained without decrease. DETAILED DESCRIPTION

[0028] The thiol-double bond or thiol-epoxy click reaction is one of the reactions frequently used in light-curing adhesives and heat-curing adhesives. It has the characteristics of fast reaction speed, high functional group conversion rate, and low surface oxygen inhibition. However, most thiol compounds have a bad smell, contain ester bond structures, and have poor water resistance, which limits the application of such reactions in electronic and electrical adhesives.

[0029] The multifunctional thiol (mercapto) silane coupling agent of the present invention has a simple synthesis process, a mild product odor, does not contain an ester bond structure, and has excellent water resistance.

[0030] The following are examples of the hydrolysis synthesis method of a multifunctional thiol silane coupling agent and the formulation of a photothermal dual-curing adhesive.

[0031] [Mercaptosilane coupling agent-1] In a three-necked glass flask with a reflux condenser, add 100 g of mercaptopropylmethyldimethoxysilane coupling agent (commercially available chemical reagent), 5 g of deionized water, 50 g of ethanol, and 0.5 g of dibutyltin bistriethoxysilicate. Stir and heat to 60°C for 5 h. Rotary evaporate to remove unreacted water, ethanol solvent and generated methanol to obtain a multifunctional mercaptosilane coupling agent-1 with a viscosity of 5.8 mPas.

[0032] [Mercaptosilane coupling agent-2] In a three-necked glass flask with a reflux condenser, add 100g of mercaptopropylmethyldimethoxysilane coupling agent, 15g of deionized water, 50g of ethanol, and 0.1g of trifluoromethanesulfonic acid. Stir and heat to 60°C for 5h, then cool to room temperature. Add excess sodium carbonate to neutralize the residual trifluoromethanesulfonic acid, filter out the solid sodium carbonate by sedimentation, and remove the ethanol solvent and the generated methanol by rotary evaporation to obtain a multifunctional thiol silane coupling agent-2 with a viscosity of 45mPas.

[0033] [Mercaptosilane coupling agent-3] In a three-necked glass flask with a reflux condenser, add 100 g of mercaptopropylmethyldimethoxysilane coupling agent, 10 g of deionized water, and 0.5 g of dibutyltin dilaurate. Stir and heat to 60°C for 5 h. Rotary evaporate to remove unreacted water and generated methanol to obtain a multifunctional mercaptosilane coupling agent-3 with a viscosity of 90 mPas.

[0034] [Mercaptosilane coupling agent-4] In a three-necked glass flask with a reflux condenser, add 90g of mercaptopropylmethyldimethoxysilane coupling agent, 10g of mercaptopropyltrimethoxysilane coupling agent, 10g of deionized water, and 0.5g of dibutyltin dilaurate. Stir and heat to 60°C for 5h. Rotary evaporation is used to remove unreacted water and generated methanol to obtain a multifunctional mercaptosilane coupling agent-4 with a viscosity of 155mPas.

[0035] [Example 1] - [Example 4] The formula is shown in Table 1, and the preparation process is the same. Add a compound with a benzene ring structure and two or more allyl ethers or allyl esters (allyl compound), a multifunctional thiol silane coupling agent, a photoinitiator, a thermal initiator, etc. to a planetary mixer and stir and mix them evenly under vacuum.

[0036] [Comparative Example 1] - [Comparative Example 2] The formula is shown in Table 1, and the preparation process is the same.

[0037] The test results of various embodiments and comparative examples are shown in Table 1.

[0038] Table 1

[0039] Example-1 Example-2 Example-3 Example-4 Comparative Example-1 Comparative Example-2 Mercaptan silane coupling agent-1 100 Thiol silane coupling agent-2 100 Thiol silane coupling agent-3 100 Thiol silane coupling agent-4 100 Diallyl Phthalate (DAP) 70 70 100 Bisphenol A bisallyl ether 85 85 100 PEMP 100 80 1173# Photoinitiator 2.0 2.0 2.0 2.0 2.0 2.0 TPO Photoinitiator 1.0 1.0 1.0 1.0 1.0 1.0 Azobis(2-isoheptanonitrile) 0.5 0.5 0.5 Lauroyl Peroxide 0.5 0.5 0.5 PC / PC shear strength (MPa) <![CDATA[Photocuring, irradiation dose 1000 mJ / cm 2 > 43 4.5 5.6 5.8 42 6.8 85℃85%RH*After 500h 4.2 4.6 5.9 6.2 1.2 1.7 90℃*60min heat curing 3.8 4.2 5.4 5.1 3.9 5.8 85℃85%RH*After 500h 3.9 4.1 5.2 5.4 0.9 1.1

[0040] Note: PEMP is pentaerythritol tetrakis(3-mercaptopropionic acid), 1173# is 2-hydroxy-2-methyl-phenylacetone-1, TPO is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Diallyl phthalate (DAP), bisphenol A bisallyl ether, azobisisoheptonitrile and lauroyl peroxide are all commercially available chemical reagents.

[0041] By comparing the results of Example 1 to Example 4 in Table 1, it can be found that the adhesive formulation of the multifunctional thiol silane coupling agent synthesized by hydrolysis can be photocured and irradiated with a high-pressure mercury lamp of 1000mJ / cm 2 , or heat curing at 90℃*60min. Regardless of light curing or heat curing, the shear strength after high temperature and high humidity did not decrease significantly. The shear strength of some formulations even increased, which may be due to further cross-linking reactions at high temperature. The shear strength of Comparative Examples 1 and 2 dropped sharply after high temperature and high humidity, indicating that the thiol compounds containing ester bond structures were severely hydrolyzed under high temperature and high humidity conditions, resulting in molecular chain breakage, and it is difficult to be used for applications that require strict moisture resistance, such as bonding or sealing of electronic and electrical components.

Claims

1. A light-heat dual-curing moisture-heat resistant adhesive composition, characterized in that: The invention comprises, by weight: 100 parts of a multifunctional thiol (mercapto) silane coupling agent, 60 to 100 parts of a compound having a benzene ring structure and two or more allyl ethers or allyl esters, 0.5 to 5 parts of a photoinitiator, and 0.5 to 5 parts of a thermal initiator.

2. The adhesive composition according to claim 1, characterized in that The compound with a benzene ring structure and two or more allyl ethers or allyl esters is selected from diallyl phthalate DAP or bisphenol A diallyl ether of the following structure:

3. The adhesive composition according to claim 1, characterized in that The photoinitiator is selected from any one or more of benzoin and its derivatives, benzil derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-aminoalkyl phenone, acylphosphorus oxide, benzophenone and its derivatives, thioxanthone compounds, anthraquinone compounds, fluorenone compounds, etc., preferably α-hydroxyalkyl phenone, acylphosphorus oxide, benzophenone and its derivatives.

4. The adhesive composition according to claim 1, characterized in that: The thermal initiator is an azo or peroxide free radical thermal initiator with a decomposition temperature of 60-100° C., preferably any one of azobisisobutyronitrile, azobisisoheptanenitrile, lauroyl peroxide and benzoyl peroxide.

5. The adhesive composition according to claim 1, characterized in that: The multifunctional thiol (mercapto) silane coupling agent has the following structure: Wherein, R represents a methyl group or a methoxy group, and n is an integer of 0 to 100.

6. The adhesive composition according to claim 1, wherein The multifunctional thiol (mercapto) silane coupling agent is synthesized by hydrolysis of mercaptopropylmethyldimethoxysilane coupling agent and / or mercaptopropyltrimethoxysilane coupling agent in the presence of a catalyst; Specifically, the catalyst is selected from any one or more of inorganic acid, organic acid, organotin compound, cation exchange resin, titanate compound, α-silane coupling agent, Lewis acid or Lewis base compound, preferably any one or more of inorganic acid, organic acid and organotin compound; the weight ratio of mercaptopropylmethyldimethoxysilane coupling agent and / or mercaptopropyltrimethoxysilane coupling agent to the catalyst is 100:0.05-2; More specifically, the inorganic acid and organic acid are hydrochloric acid, sulfuric acid, phosphoric acid, methanesulfonic acid, trifluoromethanesulfonic acid, toluenesulfonic acid, etc.; More specifically, the organotin compound is dibutyltin dibutyl ketoxime silicon, dibutyltin diacetylacetonate, dibutyltin diacetylacetate, dibutyltin dilaurate, dibutyltin bistriethoxysilicate, dioctyltin bistriethoxysilicate, and a tetravalent tin compound which is a reaction product of diketoxime tin oxide and a silicate compound.

7. The adhesive composition according to claim 1, characterized in that: The adhesive composition further comprises a silane coupling agent, which is selected from one or more of γ-methacryloxypropyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, anilinemethyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-ureapropyltriethoxysilane.

8. The adhesive composition according to claim 1, wherein The adhesive composition further comprises a filler selected from one or more of fused silica, glass fiber powder, and glass microspheres.

9. The adhesive composition according to claim 1, wherein The adhesive composition further comprises one or more of a free radical inhibitor, an antioxidant, a flame retardant, a diluent, an adhesion promoter, a dye, a pigment, a defoamer, and a leveling agent.

10. A light-heat dual-curing moisture-heat resistant adhesive, characterized in that: The adhesive composition is obtained by uniformly mixing the adhesive composition as claimed in any one of claims 1 to 9 through vacuum stirring.

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