Yellowing-resistant low-energy photocuring adhesive for optical lens and preparation method of yellowing-resistant low-energy photocuring adhesive

Abstract

The invention relates to the technical field of adhesives, in particular to a yellowing-resistant low-energy photocuring adhesive for an optical lens and a preparation method of the yellowing-resistant low-energy photocuring adhesive. The adhesive is prepared from the following raw materials in parts by mass: 30 to 75 parts of acrylate resin, 5 to 32 parts of polyester resin, 15 to 45 parts of reaction monomer, 0.5 to 8 parts of thickening agent, 0.1 to 6 parts of photoinitiator, 0.1 to 3 parts of photosensitizer and 0.1 to 5 parts of adhesion promoter, the weight ratio of the acrylate resin to the polyester resin is (2.3-7): 1. According to the invention, the hydrogenated polyester resin, compounding of monofunctional and polyfunctional reactive monomers, a photosensitizer anthraquinone derivative and the like are adopted to act together, so that the adhesive which can be cured in a single wave band of the LED lamp is obtained, and meanwhile, the mechanical strength and the stability of the adhesive are effectively improved; the obtained adhesive can be well applied to adhesion of optical lenses and has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a yellowing-resistant low-energy light-curing adhesive for optical lenses and a preparation method thereof. Background Art

[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 life. As a 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, thereby extending the service life of the LED. On the other hand, lenses can also reduce mechanical shock and thermal stress on LED chips. Therefore, the bonding and fixing of lenses and bases is particularly important for improving the reliability of LEDs.

[0003] At present, 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 and other substrates. Traditional bonding and fixing methods include two-component epoxy curing, silicone curing, etc. These processes have the disadvantage of long curing time. The curing time of UV adhesives currently on the market is significantly shortened, but there are still disadvantages such as high curing energy, the need for multi-band mercury lamp light to cure, and easy yellowing after curing, which limits the application of UV adhesives in optical lens parts.

[0004] Chinese patent CN106221642B discloses a UV-curable adhesive, which uses a compound of a specific structure as the main resin to make the UV-curable adhesive have fast curing speed, strong adhesion, good flexibility and yellowing resistance. Chinese patent CN114507479B discloses a photocurable composition, an adhesive and a preparation method thereof, and a bonding method of a substrate. The composition includes a monomer, a cationic photoinitiator, a photosensitive resin and an oligomer, and the monomer is preferably an oxetane monomer compound to solve the problem of short life of the packaging material in the prior art. However, these prior arts or raw materials are difficult to obtain, or the curing energy is high, and none of them effectively solves the above technical problems.

[0005] Under such circumstances, there is an urgent need to provide an adhesive with low curing energy, strong adhesion and yellowing resistance to meet the needs of optical lens manufacturing. Summary of the invention

[0006] Based on the problems existing in the UV glue for optical lenses currently on the market, the present invention provides a yellowing-resistant low-energy light-curing adhesive for optical lenses and a preparation method thereof, which has the advantages of high transparency, yellowing resistance, and firm bonding with lenses / substrates. In addition, the UV glue will not corrode the substrate, is safe, friendly and easy to implement.

[0007] The first aspect of the present invention provides a yellowing-resistant low-energy light-curing adhesive for optical lenses. The raw materials for preparing the adhesive include, by weight: 30 to 75 parts of acrylate resin, 5 to 32 parts of polyester resin, 15 to 45 parts of reactive monomers, 0.5 to 8 parts of thickener, 0.1 to 6 parts of photoinitiator, 0.1 to 3 parts of photosensitizer, and 0.1 to 5 parts of adhesion promoter.

[0008] Further preferably, the raw materials for preparing the adhesive include: 40-60 parts of acrylate resin, 10-20 parts of polyester resin, 20-40 parts of reactive monomers, 1-5 parts of thickener, 1-4 parts of photoinitiator, 0.1-1 part of photosensitizer, and 1-2 parts of adhesion promoter.

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

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

[0011] In some preferred embodiments, the polyester resin is hydrogenated; the hydrogenated polyester resin may be commercially available, and suppliers include Lawter Company; products include Lawter F85C and Lawter2000C.

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

[0013] The core of the present invention is a hydrogenated polyester resin, especially Lawter F85C and Lawter2000C, which can 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 because the molecular structure of the hydrogenated polyester resin contains many saturated carbon-carbon bonds, its addition can enhance the chemical stability of the UV adhesive, thereby helping to improve the adhesion.

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

[0015] In order to take into account both the hardness and toughness of the adhesive, in some preferred embodiments, the reactive monomer includes a monofunctional reactive monomer and a polyfunctional reactive monomer, and the weight ratio of the monofunctional reactive monomer to the polyfunctional reactive monomer is (1-4):1; further preferably (1-2):1.

[0016] Examples of the monofunctional reactive monomer include hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0017] In some preferred embodiments, the monofunctional reactive monomer includes hydroxyethyl acrylate.

[0018] Examples of the polyfunctional monomer include ditrimethylolpropane tetraacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and trimethylolpropane triacrylate.

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

[0020] Examples of the thickener include fumed silica, talc, calcium carbonate, and the like.

[0021] In some preferred embodiments, the thickener is fumed silica, which may be exemplified by Evonik A200 and Evonik A380.

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

[0023] In some preferred embodiments, the photosensitizer includes anthraquinone derivatives, which may be exemplified by PAS-33 and photosensitizer 395 (5-(4-diphenylaminephenylvinyl)-phenethyloxazolidine-2,4-dione, CAS No. 506426-96-6).

[0024] The preferred photosensitizer of the present invention includes anthraquinone derivatives, which only need to be added to the adhesive system at 0.1-1% to significantly improve the light initiation efficiency, thereby prompting the adhesive to be completely cured under the irradiation of a single-band LED lamp (365nm), solving the technical problem that the existing UV adhesive requires multi-band mercury lamp illumination to cure and is difficult to operate. The more preferred photosensitizer of the present invention is Youyang PAS-33, which has a sensitizing effect on the system, has a very high sensitivity to ultraviolet light, and further optimizes the curing efficiency of the UV adhesive.

[0025] In some preferred embodiments, the adhesion promoter includes one or more of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri(β-methoxyethoxy) silane, and vinyl triperoxide tert-butyl silane.

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

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

[0028] The second aspect of the present invention provides a method for preparing a yellowing-resistant low-energy light-curing adhesive for an optical lens, the preparation steps of the adhesive comprising:

[0029] S1. The photoinitiator, photosensitizer, polyester resin and reactive monomer are mixed and dissolved to obtain a mixture;

[0030] S2. Add a mixture to the acrylic resin, stir and mix evenly, then sequentially add an adhesion promoter and a thickener, disperse evenly to obtain a mixture of two;

[0031] S3. The mixed material is vacuum-evacuated for degassing to obtain a finished adhesive.

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

[0033] In some preferred embodiments, the thickener is added in multiple times; more preferably, the thickener is added in 2 to 3 times, with the same amount added each time.

[0034] Beneficial effects:

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

[0036] (1) The present invention uses hydrogenated polyester resin (such as Lawter F85C, Lawter 2000C) and acrylate resin to effectively improve the bonding strength and yellowing resistance of the adhesive, so that its application in optical lenses can improve the reliability of the manufactured parts.

[0037] (2) The present invention uses a multifunctional monomer ditrihydroxymethylpropane tetraacrylate and a single-functional reactive monomer hydroxyethyl acrylate to compound, which can make the adhesive have a stable three-dimensional network polymerization structure, thereby having both support and flexibility to meet the use requirements.

[0038] (3) The present invention uses an anthraquinone derivative as a photosensitizer to enhance the curing reaction activity of the formulation system and improve the initiation efficiency, so that the adhesive can be completely cured under the irradiation of a single-band LED lamp (365nm), thereby solving the technical problems of high curing energy and difficult processing and operation of existing adhesives.

[0039] (4) The present invention uses vinyltrimethoxysilane as an adhesion promoter, which can improve the reaction efficiency, strengthen the bonding properties of the adhesive, and improve the comprehensive performance of the resulting adhesive. It can be placed at above 100°C for 200 hours without any abnormalities, and the bonding strength is further improved, thereby achieving a firm connection of the lens.

[0040] (5) The raw materials of the present invention are easily available, the process is simple, and the demand for mass production can be met, and it is easy to promote. DETAILED DESCRIPTION

[0041] The present invention adopts the polyester resin after hydrogenation treatment, the compound of monofunctional and multifunctional reaction monomers and the photosensitizer anthraquinone derivatives to jointly obtain an adhesive that can be cured in a single band of LED lamp, and through the screening of raw materials and the control of the formula amount, the mechanical strength and stability of the adhesive are finally effectively improved. The obtained adhesive can be well used for the bonding of optical lenses and has a good application prospect.

[0042] Example

[0043] Examples 1 to 3 and Comparative Examples 1 to 2 respectively provide a yellowing-resistant low-energy light-curing adhesive for an optical lens, 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 binder include:

[0048] S1. The photoinitiator, photosensitizer, polyester resin and reactive monomer are mixed and dissolved to obtain a mixture;

[0049] S2. Add a mixture to the acrylic resin, stir and mix at 800r / min, then add an adhesion promoter and a thickener, disperse evenly to obtain a mixture of two;

[0050] S3. The mixed material is vacuum-evacuated for degassing to obtain a finished adhesive.

[0051] The thickener is added in two portions, with each addition amounting to 1 / 2 of the formula amount.

[0052] 1. Cases where using photoinitiator alone does not produce good results:

[0053] No photosensitizer added: Cured by LED light, not dry after oven;

[0054] 2. Other reactive monomers - cases with poor results:

[0055] Replace hydroxyethyl acrylate with: TMCHA, CTFA, EHMA, IBOMA are not as good as hydroxyethyl acrylate, and they all fall in the drop test.

[0056] Comparative Example 3

[0057] A yellowing-resistant low-energy light-curing adhesive for optical lenses, the specific implementation method is the same as that of Example 3, except that no photosensitizer is added. The final sample is cured by LED light, but it is not dry after passing through the oven and cannot be used normally.

[0058] Comparative Example 4

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

[0060] Comparative Example 5

[0061] A yellowing-resistant low-energy light-curing adhesive for optical lenses, the specific implementation method is the same as that of Example 3; the difference is that hydroxyethyl acrylate is replaced by CTFA (cyclotrimethylolpropane formal acrylate), and the sample falls during the drop test.

[0062] Comparative Example 6

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

[0064] Comparative Example 7

[0065] A yellowing-resistant low-energy light-curing adhesive for optical lenses, the specific implementation method is the same as that of Example 3; the difference is that hydroxyethyl acrylate is replaced by IBOMA (isobornyl methacrylate), and the sample falls during the drop test.

[0066] Performance Testing

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

[0068] Shear strength: Apply adhesive between PMMA and aluminum plate in an amount the size of a soybean; then UV cure the sample and test it.

[0069] Drop test: Apply adhesive between the lens and the substrate to make a lens sample. Set 10 samples as a group, and drop 5 groups from a height of 2m at the same time to observe the lens drop. The coating method is three-point coating, take 3 points on the circumference of a 0.3cm diameter, apply soybean-sized, and then UV cure.

[0070] High temperature resistance: Place the sample at 105℃ for 200h, take it out and observe whether there is yellowing or bubbles.

[0071] Table 2

[0072]

[0073] Note: The sample is placed in an LED curing oven for curing at a set curing energy and a curing wavelength of 365nm.

[0074] It can be seen from the above table that the adhesive prepared by the preferred embodiment of the present invention has excellent performance, low required curing energy, high bonding strength between the lens and the substrate, good high temperature yellowing resistance, and reliability. When the amount of polyester resin added is small, although it can help improve the yellowing resistance, high temperature resistance and adhesion of the adhesive, the thrust of the adhesive becomes worse and the performance of the adhesive is significantly deteriorated.

Claims

1. A yellowing-resistant low-energy light-curing adhesive for optical lenses, characterized in that: The raw materials for preparing the adhesive include, by weight: 30 to 75 parts of acrylate resin, 5 to 32 parts of polyester resin, 15 to 45 parts of reactive monomer, 0.5 to 8 parts of thickener, 0.1 to 6 parts of photoinitiator, 0.1 to 3 parts of photosensitizer, and 0.1 to 5 parts of adhesion promoter; The weight ratio of the acrylic resin to the polyester resin is (2.3-7):

1.

2. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 1, characterized in that: The polyester resin is hydrogenated.

3. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 1, characterized in that: The reactive monomers include monofunctional reactive monomers and multifunctional reactive monomers, and the weight ratio of the monofunctional reactive monomers to the multifunctional reactive monomers is (1-4):

1.

4. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 3, characterized in that: The monofunctional reactive monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate; Preferably, the monofunctional reactive monomer includes hydroxyethyl acrylate.

5. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 4, characterized in that: The multifunctional monomer includes at least one of ditrimethylolpropane tetraacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate and trimethylolpropane triacrylate; Preferably, the multifunctional monomer includes ditrihydroxymethylpropane tetraacrylate.

6. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 1, characterized in that: The photoinitiator comprises a compound of 1-hydroxycyclohexyl phenyl ketone and benzophenone.

7. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 1, characterized in that: The photosensitizer includes anthraquinone derivatives.

8. The yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 1, characterized in that: The adhesion promoter includes one or more of vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(β-methoxyethoxy)silane, and vinyl triperoxide tert-butylsilane.

9. A method for preparing the yellowing-resistant low-energy light-curing adhesive for optical lenses according to any one of claims 1 to 8, characterized in that: The preparation steps of the adhesive include: S1. The photoinitiator, photosensitizer, polyester resin and reactive monomer are mixed and dissolved to obtain a mixture; S2. Add a mixture to the acrylic resin, stir and mix evenly, then sequentially add an adhesion promoter and a thickener, disperse evenly to obtain a mixture of two; S3. The mixed material is vacuum-evacuated for degassing to obtain a finished adhesive.

10. The method for preparing the yellowing-resistant low-energy light-curing adhesive for optical lenses according to claim 9, characterized in that: The stirring rate of the step S2 is 500-1500 r / min.

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