Anti-yellowing low-energy light-curing adhesive for optical lens and preparation method thereof

Abstract

The present application relates to the technical field of adhesive, in particular to a yellowing-resistant low-energy light-cured adhesive for optical lens and a preparation method thereof.According to mass parts, the preparation raw materials of the adhesive include: 30-75 parts of acrylate resin, 5-32 parts of polyester resin, 15-45 parts of reaction monomer, 0.5-8 parts of thickening agent, 0.1-6 parts of photoinitiator, 0.1-3 parts of photosensitive sensitizer and 0.1-5 parts of adhesion promoter; the weight ratio of the acrylate resin and the polyester resin is (2.3-7):1.The polyester resin treated by hydrogenation, the single functionality and multifunctionality reaction monomer compound and the photosensitive sensitizer anthraquinone derivative jointly work to obtain the adhesive which can be cured by LED lamp single wave band, and effectively improve the mechanical strength and stability of the adhesive, and the obtained adhesive can be well applied to the bonding of optical lens and has good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to a yellowing-resistant low-energy light-curable adhesive for optical lenses and a preparation method thereof. BACKGROUND

[0002] In the development of modern lighting technology, LED lamps have become widely used light sources due to their high efficiency, low energy consumption, and long service life. As part of LED lamps, lenses can protect LED chips. On the one hand, they can prevent dust, water vapor, and other impurities from entering the LED interior, thereby extending the service life of the LED. On the other hand, they can also reduce the mechanical impact and thermal stress on the LED chip. Therefore, the adhesion and fixation of the lens to the base are particularly important for improving the reliability of the LED.

[0003] Currently, the base of LED lamps is generally a metal heat sink (such as aluminum, copper, iron, etc.), and the optical lens is generally made of PMMA, PC, glass, etc. Traditional adhesion and fixation methods include two-component epoxy curing and silicone curing, which have the disadvantage of long curing time. The curing time of UV adhesives on the market has been significantly shortened, but there are still disadvantages such as high curing energy, the need for multiple wavelength light from a mercury lamp for curing, and easy yellowing after curing, which limits the application of UV adhesives in optical lens products.

[0004] Chinese patent CN106221642B discloses a kind of ultraviolet light curing adhesive, by the compound of specific structure as main body resin, make ultraviolet light curing adhesive have fast curing speed, strong adhesion, good flexibility and yellowing resistance. Chinese patent CN114507479B discloses a kind of light curing composition, adhesive and preparation method thereof, and the bonding method of base material, the composition includes monomer, cationic photoinitiator, photosensitive resin and oligomer, and the monomer is preferably oxetane monomer compound to solve the problem of short service life of existing packaging materials. However, these existing technologies or raw materials are difficult to obtain, or have high curing energy, and the above technical problems have not been effectively solved.

[0005] Under such circumstances, it is urgent to provide a yellowing-resistant low-energy light-curable adhesive with low curing energy, strong adhesion, and yellowing resistance to meet the needs of optical lens products. SUMMARY

[0006] Based on the problems of UV adhesives for optical lenses on the market, the present application provides a yellowing-resistant low-energy light-curable adhesive for optical lenses and a preparation method thereof, which has the advantages of high transparency, yellowing resistance, and firm adhesion to lenses and substrates. The UV adhesive does not corrode the substrate, is safe and friendly, and is easy to implement.

[0007] The present application provides a yellowing-resistant low-energy light-cured adhesive for optical lens, which is prepared from the following raw materials in parts by mass: 30-75 parts of an acrylate resin, 5-32 parts of a polyester resin, 15-45 parts of a reactive monomer, 0.5-8 parts of a thickening agent, 0.1-6 parts of a photoinitiator, 0.1-3 parts of a photosensitive sensitizer, and 0.1-5 parts of an adhesion promoter.

[0008] Further preferably, the adhesive is prepared from the following raw materials in parts by mass: 40-60 parts of an acrylate resin, 10-20 parts of a polyester resin, 20-40 parts of a reactive monomer, 1-5 parts of a thickening agent, 1-4 parts of a photoinitiator, 0.1-1 parts of a photosensitive sensitizer, and 1-2 parts of an adhesion promoter.

[0009] In some preferred embodiments, the acrylate resin comprises one or more of a combination of monofunctional polyurethane acrylate, multifunctional polyurethane acrylate, aliphatic polyurethane acrylate, and silicone-modified polyurethane acrylate.

[0010] Further preferably, the acrylate resin is aliphatic polyurethane acrylate, such as Changxing 61355, which is a product with moderate initial tack and adhesion.

[0011] In some preferred embodiments, the polyester resin is hydrogenated; hydrogenated polyester resin is commercially available, such as from supplier Lawter; products can be listed as Lawter F85C and Lawter 2000C.

[0012] In some preferred embodiments, the polyester resin is added to the adhesive formulation in an amount of 9-25 wt%, further preferably 10-20 wt%; can be listed as 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 14.5 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, and 20 wt%.

[0013] The present application uses hydrogenated polyester resin, especially Lawter F85C and Lawter 2000C, to significantly improve the yellowing resistance of the adhesive; and the adhesion of the obtained adhesive to the substrate is significantly improved. It is speculated that the hydrogenated polyester resin contains many saturated carbon-carbon bonds in its molecular structure, so its addition can enhance the chemical stability of the UV adhesive, thereby helping to improve the adhesion.

[0014] In order to improve the adhesion of the adhesive, in some preferred embodiments, the weight ratio of the acrylate resin to the polyester resin is (2.3-7):1. When the ratio exceeds the preferred range, the adhesion strength of the adhesive will decrease, affecting the quality of the product.

[0015] In order to balance the hardness and toughness of the adhesive, in some preferred embodiments, the reaction monomer comprises a monofunctional reaction monomer and a multifunctional reaction monomer, and the weight ratio of the monofunctional reaction monomer and the multifunctional reaction monomer is (1-4): 1; further preferably (1-2): 1.

[0016] The monofunctional reaction monomer can be listed as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc.

[0017] In some preferred embodiments, the monofunctional reaction monomer comprises hydroxyethyl acrylate.

[0018] The multifunctional monomer can be listed as ditrimethylolpropane tetraacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, etc.

[0019] In order to further improve the support and stability of the adhesive, in some preferred embodiments, the multifunctional monomer comprises ditrimethylolpropane tetraacrylate.

[0020] The thickening agent can be listed as fumed silica, talc, calcium carbonate, etc.

[0021] In some preferred embodiments, the thickening agent is fumed silica, which can be listed as Wacker A200, Wacker A380.

[0022] In some preferred embodiments, the photoinitiator comprises a compound of 1-hydroxy cyclohexyl phenyl ketone (commonly known as photoinitiator 184) and benzophenone (commonly known as photoinitiator BP). Further preferably, the photoinitiator comprises Norton Chemical E-500 and 1-hydroxy cyclohexyl phenyl ketone; the weight ratio of the Norton Chemical E-500 and 1-hydroxy cyclohexyl phenyl ketone is (0.8-2.5): 1; further preferably (1-2): 1. The product of Norton Chemical E-500 is a mixture of 184 and BP.

[0023] In some preferred embodiments, the photosensitive sensitizer comprises an anthraquinone derivative; which can be listed as Youyang PAS-33, photosensitive sensitizer 395 (5-(4-diphenylamine phenyl vinyl)-phenethyl oxazolidine-2,4-dione, CAS number 506426-96-6).

[0024] The preferred photosensitive sensitizer of the present application includes an anthraquinone derivative, which only needs to be added in an amount of 0.1-1% in the adhesive system, so as to obviously improve the light initiation efficiency, thereby promoting the complete curing of the adhesive under the single waveband (365nm) irradiation of an LED lamp, and solving the technical problem that the existing UV adhesive needs to be cured under the multi-waveband irradiation of a mercury lamp, and the operation is more difficult. The more preferred photosensitive sensitizer of the present application is Youyang PAS-33, which has a sensitization effect on the system and has very high sensitivity to ultraviolet light, and further optimizes the curing efficiency of the UV adhesive.

[0025] In some preferred embodiments, the adhesion promoter comprises a combination of one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(beta-methoxyethoxy)silane, and vinyltris(tert-butyiper- oxysilane).

[0026] In order to improve the curing reaction efficiency of the adhesive and further improve its adhesion, it is further preferred that the adhesion promoter comprises vinyltrimethoxysilane.

[0027] In some preferred embodiments, the adhesion promoter is added in an amount of 1-5wt% in the adhesive formulation; more preferably, 2wt%.

[0028] The second aspect of the present application provides a preparation method of a yellowing-resistant low-energy light-cured adhesive for optical lenses, and the preparation steps of the adhesive comprise:

[0029] S1. Mixing and dissolving a photoinitiator, a photosensitive sensitizer, a polyester resin, and a reaction monomer to obtain a mixture one;

[0030] S2. Adding the mixture one to an acrylate resin, stirring and mixing uniformly, then sequentially adding an adhesion promoter and a thickening agent, and dispersing uniformly to obtain a mixture two;

[0031] S3. Vacuum deaerating the mixture two to obtain an adhesive finished product.

[0032] In some preferred embodiments, the stirring rate of the S2 step is 500-1500r / min, more preferably 800r / min.

[0033] In some preferred embodiments, the thickening agent is added in multiple times; more preferably, the thickening agent is added in 2-3 times, and the amount of each addition is the same.

[0034] Advantages:

[0035] The present application provides a yellowing-resistant low-energy light-cured adhesive for optical lenses and a preparation method, which has the following advantages:

[0036] (1) The application adopts hydrogenated polyester resin (such as Lawter F85C, Lawter 2000C) and acrylate resin to improve the bonding strength and yellowing resistance of the bonding glue, so that the reliability of the optical lens can be improved.

[0037] (2) The application adopts multifunctional monomer ditrimethylolpropane tetraacrylate and monofunctional monomer hydroxyethyl acrylate to make the bonding glue have a stable three-dimensional network polymerization structure, so as to have support and flexibility, and meet the use requirements.

[0038] (3) The application adopts anthraquinone derivatives as photosensitive sensitizer to improve the curing reaction activity of the formula system, improve the initiation efficiency, so that the bonding glue can be completely cured under the single waveband (365nm) of the LED lamp, and the technical problems of high curing energy and difficult processing operation of the existing bonding glue are solved.

[0039] (4) The application adopts vinyltrimethoxysilane as the adhesion promoter to improve the reaction efficiency, strengthen the bonding properties of the bonding glue, and improve the comprehensive performance of the obtained bonding glue, so that the bonding strength is further improved, and the lens can be firmly connected.

[0040] (5) The raw materials are easy to obtain, and the process is simple, so that the demand of batch production can be met, and the application can be easily promoted. DETAILED DESCRIPTION

[0041] The application adopts hydrogenated polyester resin, monofunctional and multifunctional monomers, and anthraquinone derivatives as photosensitive sensitizer to obtain a bonding glue that can be cured under the single waveband of the LED lamp, and through the selection of raw materials and the control of formula amount, the mechanical strength and stability of the bonding agent are effectively improved, and the obtained bonding glue can be well applied to the bonding of optical lenses, and has good application prospect.

[0042] EMBODIMENT

[0043] Embodiments 1-3 and comparative examples 1-2 respectively provide a yellowing-resistant low-energy light-cured bonding glue for optical lenses, and the components are shown in Table 1 below.

[0044] Table 1

[0045]

[0046] Note: The values in Table 1 are parts by weight.

[0047] The preparation steps of the bonding agent include:

[0048] S1. Mix, dissolve the photoinitiator, photosensitive sensitizer, polyester resin and reactive monomer to obtain mixture one;

[0049] S2. Add mixture one to the acrylate resin, stir at 800 r / min to mix evenly, then add the adhesion promoter and thickening agent in turn, disperse evenly to obtain mixture two;

[0050] S3. Vacuum deaeration of mixture two to obtain the finished adhesive.

[0051] The thickening agent is added in two times, and the amount of each time is 1 / 2 of the formula amount.

[0052] 1. Case of poor effect of using photoinitiator alone:

[0053] Without adding photosensitive sensitizer: curing with LED lamp, not dry after oven;

[0054] 2. Case of poor effect of other reactive monomers:

[0055] Replacing hydroxyethyl acrylate with TMCHA, CTFA, EHMA, IBOMA, none of them is as good as hydroxyethyl acrylate, and all of them fall off in the drop test.

[0056] Comparative Example 3

[0057] A yellowing-resistant low-energy light-cured adhesive for optical lenses, the specific implementation is the same as Example 3; the difference is that no photosensitive sensitizer is added. The final sample is cured with an LED lamp, and it is not dry after the oven, which cannot be used normally.

[0058] Comparative Example 4

[0059] A yellowing-resistant low-energy light-cured adhesive for optical lenses, the specific implementation is the same as Example 3; the difference is that hydroxyethyl acrylate is replaced by TMCHA (3,3,5-trimethylcyclohexyl acrylate), and the sample falls off in the drop test.

[0060] Comparative Example 5

[0061] A yellowing-resistant low-energy light-cured adhesive for optical lenses, the specific implementation is the same as Example 3; the difference is that hydroxyethyl acrylate is replaced by CTFA (cyclo-trihydroxymethylpropane methyl acetal acrylate), and the sample falls off in the drop test.

[0062] Comparative Example 6

[0063] A yellowing-resistant low-energy light-cured adhesive for optical lenses, the specific implementation is the same as Example 3; the difference is that hydroxyethyl acrylate is replaced by EHMA (isooctyl methacrylate), and the sample falls off in the drop test.

[0064] Comparative Example 7

[0065] A yellowing-resistant low-energy light-cured adhesive for optical lenses, the embodiment is the same as Example 3; the difference is that the hydroxyethyl acrylate is replaced by IBOMA (isobornyl methacrylate), and sample falling occurs in the drop test.

[0066] Performance test

[0067] The adhesives prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are shown in Table 2 below.

[0068] Shear strength: the adhesive was coated between the acrylic (PMMA) / aluminum plate, the amount of glue was the size of a soybean; then the sample was UV cured and tested.

[0069] Drop test: the adhesive was coated between the lens and the substrate to prepare a lens sample, 10 samples were set as a group, and every 5 groups were dropped from 2m high at the same time to test the lens falling condition. The coating method was three-point coating, taking 3 points on the circumference of a 0.3cm diameter circle, coating the size of a soybean, and then UV curing.

[0070] High temperature resistance: the sample was placed in a 105℃ environment for 200h, and then taken out to observe whether there was yellowing or bubble phenomenon.

[0071] Table 2

[0072]

[0073] Note: The sample was cured in an LED curing oven with a set curing energy, and the curing wavelength was 365nm.

[0074] As can be seen from the above table, the adhesive prepared by the preferred scheme of the present application has excellent performance, low required curing energy, high adhesive strength of the lens and the substrate, good high temperature yellowing resistance effect, and reliability can pass the test. When the amount of polyester resin is small, although it can help to improve the yellowing resistance, high temperature resistance and adhesion of the adhesive, the thrust of the adhesive is poor, and the performance of the adhesive is obviously deteriorated.

Claims

1. A low-energy photocurable adhesive for optical lenses that resists yellowing, characterized in that, The raw materials for preparing the adhesive, by weight, include: 30-75 parts of acrylate resin, 5-32 parts of polyester resin, 15-45 parts of reactive monomer, 0.5-8 parts of thickener, 0.1-6 parts of photoinitiator, 0.1-3 parts of photosensitizer, and 0.1-5 parts of adhesion promoter. The weight ratio of the acrylate resin to the polyester resin is (2.3-7):1; The acrylate resin includes aliphatic polyurethane acrylate; The polyester resin includes at least one of Lawter 2000C and Lawter F85C; The reactive monomers include monofunctional reactive monomers and polyfunctional reactive monomers, and the weight ratio of the monofunctional reactive monomers to the polyfunctional reactive monomers is (1-4):1; The monofunctional reactive monomer includes hydroxyethyl acrylate; The photosensitizer includes anthraquinone derivatives.

2. The low-energy photocurable adhesive for optical lenses with anti-yellowing properties according to claim 1, characterized in that, The multifunctional monomers include at least one of bis(trimethylolpropane)tetraacrylate, pentaerythritol tetraacrylate, and trimethylolpropane triacrylate.

3. The low-energy photocurable adhesive for optical lenses with anti-yellowing properties according to claim 2, characterized in that, The multifunctional monomer includes bis(trihydroxymethylpropane)tetraacrylate.

4. The low-energy photocurable adhesive for optical lenses with anti-yellowing properties according to claim 1, characterized in that, The photoinitiator comprises a combination of 1-hydroxycyclohexylphenyl ketone and benzophenone.

5. The low-energy photocurable adhesive for optical lenses with anti-yellowing properties according to claim 1, characterized in that, The adhesion promoter includes one or more combinations of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, and vinyltriterperoxytert-butylsilane.

6. A method for preparing a low-energy photocurable adhesive for optical lenses that is resistant to yellowing, according to any one of claims 1-5, characterized in that, The preparation steps of the adhesive include: S1. Mix and dissolve the photoinitiator, photosensitizer, polyester resin and reactive monomer to obtain mixture one; S2. Add mixture one to the acrylic resin, stir and mix evenly, then add adhesion promoter and thickener in sequence, disperse evenly, to obtain mixture two; S3. Vacuum degas the mixture twice to obtain the finished adhesive.

7. The method for preparing the yellowing-resistant, low-energy photocurable adhesive for optical lenses according to claim 6, characterized in that, The stirring rate in step S2 is 500-1500 r / min.

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