Low-shrinkage UV moisture dual-curing adhesive and preparation method thereof

Abstract

The invention relates to a low-shrinkage UV and moisture dual-curing adhesive and a preparation method, and belongs to the field of electronic adhesives, the low-shrinkage UV and moisture dual-curing adhesive comprises the following components by weight: 10-20 parts of urethane acrylate resin, 10-20 parts of a silane-terminated modified urethane acrylate polymer, 5-20 parts of a reaction type acrylate monomer, 1-5 parts of a curing agent, 1-5 parts of a curing agent, and 1-5 parts of a curing agent. The photoinitiator, the moisture scavenger, the catalyst, the filler, the fumed silica and the additive are sequentially arranged from 1 part to 2 parts, 0.5-2 parts, 0.5-1 part, 0.5-1 part, 0.5-1 part, 0.5-2 parts, 0-2 parts and 0.5-1 part. The UV and moisture dual-curing adhesive prepared by the invention has the advantages of extremely low curing shrinkage, high hardness and bonding strength, low thermal expansion coefficient and good storage stability, and is suitable for sealing of consumer electronics or an alignment process in the lens industry.

Description

Technical Field

[0001] The invention belongs to the field of electronic adhesives, and particularly relates to a low-shrinkage UV-moisture dual-curing adhesive and a preparation method thereof. Background Art

[0002] Optical lenses, as core components of modern optical systems, are widely used in consumer electronics, medical devices, industrial inspection, and other fields. As optical lenses advance toward higher precision and miniaturization, traditional adhesive materials are no longer able to meet their manufacturing needs. UV adhesive, with its fast curing, low shrinkage, and high bond strength, has gradually become the preferred material for optical lens bonding. Especially in the manufacture of precision optical lenses, UV adhesive must not only meet mechanical performance requirements but also possess excellent optical properties and process compatibility.

[0003] The commonly used fixing glues on the market are basically based on acrylate and epoxy systems. Since there are usually obstructions between modules, shadow areas that cannot be illuminated will be formed, so usually UV curing is followed by heat curing for auxiliary curing so that the shadow areas can be completely cured. In this process, since the thermal expansion coefficient of the module accessories and the glue is usually very different, the alignment accuracy will decrease after cooling. Especially in the lens industry, out of focus is prone to occur, resulting in the need for secondary alignment. In addition, after the UV is applied, the glue will produce a cross-linking reaction, and some shrinkage will occur in the process of changing from liquid to solid. The shrinkage will be further amplified during the heating process, which will cause slight displacement of the module and affect the alignment effect of the lens. Overall, heating not only adds an extra step to the production process, but also has a high adverse effect on the accuracy of alignment.

[0004] The adhesives on the market generally have a thermal curing temperature greater than 80 degrees, a curing shrinkage rate greater than 1%, and a thermal expansion coefficient α1 that is basically above 50ppm. Therefore, during the assembly process, very high requirements are placed on the production process. Due to the intensification of market competition, the demand for higher-precision electronic products is increasing, and the requirements for electronic adhesives will also become higher and higher. There is an urgent need for adhesive products with lower curing temperatures, curing shrinkage rates, and lower thermal expansion coefficients. To this end, the present application proposes a UV-moisture dual-curing adhesive with low curing shrinkage and a preparation method. Summary of the Invention

[0005] In light of the aforementioned shortcomings of the prior art, the present invention provides a UV-moisture dual-cure adhesive with low cure shrinkage and a preparation method, aiming to address the module displacement caused by adhesive cure shrinkage in the prior art. The UV-moisture dual-cure adhesive provided by the present invention offers advantages such as low shrinkage, low CTE, no need for thermal curing, high-temperature resistance, excellent storage stability, and a long service life.

[0006] One of the purposes of the present invention is a low-shrinkage UV-moisture dual-curing adhesive, comprising the following components in parts by weight: 10-20 parts of a polyurethane acrylate resin, 10-20 parts of a silane-terminated modified polyurethane acrylate polymer, 5-20 parts of a reactive acrylate monomer, 0.5-2 parts of a photoinitiator, 0.5-1 parts of a water scavenger, 0.5-2 parts of a catalyst, 20-50 parts of a filler, 0-2 parts of fumed silica, 0-2 parts of an antioxidant, and 0.5-1 parts of an additive.

[0007] Furthermore, the polyurethane acrylate resin is any one of a polyether polyurethane acrylate polymer and a polyester polyurethane acrylate polymer.

[0008] The benefit of adopting the above further solution is that the polyether polyurethane acrylate can provide higher flexibility and the polyester polyurethane acrylate can provide higher hardness.

[0009] Furthermore, the silane-terminated modified polyurethane acrylate polymer is a mixture of any one or more of α-dimethoxysilane-modified acrylate polymer and γ-trimethoxysilane-modified acrylate polymer.

[0010] The benefits of this approach are that α-dimethoxysilane-modified acrylate polymers offer faster moisture cure speeds, while γ-trimethoxysilane-modified acrylate polymers offer slower moisture cure speeds but lower cure shrinkage. Furthermore, both resins contain carbon-carbon double bonds that can form hinge networks upon photocuring.

[0011] Furthermore, the reactive monomer comprises a soft monomer and a hard monomer: the soft monomer is preferably one or a mixture of 2(2-ethoxyethoxy)ethyl acrylate, isooctyl acrylate, isodecyl acrylate, tetrahydrofuran acrylate, hydroxyethyl acrylate, and dodecyl acrylate;

[0012] The hard monomer is preferably one or a mixture of isobornyl acrylate, N,N-2-methacrylamide, acryloylmorpholine, acrylic acid, N-vinyl pyrrolidone, and 3,3,5-trimethylcyclohexane acrylate.

[0013] Furthermore, the photoinitiator is one or a mixture of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphosphonate, ethyl 4-dimethylaminobenzoate, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0014] Furthermore, the desiccant is vinyltrimethoxysilane.

[0015] The beneficial effect of adopting the above further solution is that compared with ethoxysilane, methoxysilane can undergo hydrolysis reaction with water in the system more quickly, which can greatly reduce the time required for pretreatment during the production process.

[0016] Furthermore, the catalyst is one of dibutyltin dilaurate and aminosilane, or a mixture thereof.

[0017] Furthermore, the filler is a mixture of silicon micropowder and fumed silica.

[0018] The beneficial effect of adopting the above further solution is that the silicon powder can greatly reduce the thermal expansion coefficient of the system, while providing high hardness and wear resistance, reducing the shrinkage produced during the UV curing process. At the same time, the fumed silica can provide higher thixotropy, thereby controlling the size and shape of the glue, facilitating construction.

[0019] Furthermore, the antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and pentaerythritol tetrakis(3-laurylthiopropionate).

[0020] The beneficial effect of adopting the above further scheme is that the combination of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and pentaerythritol tetrakis(3-laurylthiopropionate) can effectively inhibit the thermal oxidative degradation of the colloid during aging testing and reduce the yellowing effect of the system;

[0021] Furthermore, the general structural formula of the additive is as follows:

[0022] F(CF2)m(CH2)nH

[0023] Furthermore, the additive is one or a mixture of Japan Morinaga FCS-005, US DuPont ZONYL FS-300, and US 3M Company FC-4430.

[0024] The beneficial effect of adopting the above further solution is that the fluorocarbon surfactant can greatly reduce the surface tension of the system and improve the wettability to the substrate.

[0025] A second object of the present invention is to provide a method for preparing the above-mentioned low shrinkage UV moisture dual curing adhesive, the specific preparation steps are as follows:

[0026] Step 1: Pretreatment: All monomers are filtered through molecular sieves to remove water from the system, and the water content is tested by titration with a Karl Fischer moisture meter to be less than 0.1%; the filler needs to be baked to 120 degrees to ensure complete drying;

[0027] Step 2: Add photoinitiator, antioxidant and reactive monomer according to the above weight ratio, heat to 45-60 degrees and stir until completely dissolved;

[0028] Step 3: After cooling the liquid from step 2 to room temperature, add polyurethane acrylate resin, silane modified polymer, water scavenger, filler, and additives, and disperse at 3000 rpm for 10-30 minutes;

[0029] Step 4: After cooling the mixture in step 2 to room temperature, add the moisture catalyst and stir at low speed for 5-10 minutes in an ice-water bath to mix evenly. During the stirring period, control the system temperature not to exceed 30 degrees.

[0030] Step 5: Vacuum stirring and degassing for 10 minutes, controlling the stirring speed to below 500 rpm to ensure that stirring does not generate heat;

[0031] Step 6: Filter the product of step 4 through a 200-mesh filter to obtain a low-curing shrinkage UV-moisture dual-curing adhesive.

[0032] As described above, the present invention provides a low shrinkage UV moisture curing adhesive and a preparation method thereof, the characteristics and beneficial effects of which are:

[0033] 1. The shadowed area does not need to be heated for curing, but can be cured by absorbing moisture from the air;

[0034] 2. Curing shrinkage rate <1%;

[0035] 3. Modulus >500MPa;

[0036] 4. Thermal expansion coefficient α1 is less than 40ppm.

[0037] The UV-humidity dual-curing glue of the present invention can provide a good alignment and sealing glue for the consumer electronics and lens industries. It does not require heating for curing, avoiding the dimensional offset problem caused by the inconsistent thermal expansion coefficients of the colloid and the substrate during the heating and cooling process. At the same time, it can effectively reduce the curing shrinkage rate of the glue after UV, greatly improving the alignment accuracy, and providing the consumer electronics industry with an adhesive product with excellent performance, stable storage and long service life. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with specific implementation cases. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0039] Example 1

[0040] Accurately weigh 2g of hydroxyethyl acrylate, 25g of isobornyl acrylate, 15g of acryloylmorpholine, 0.6g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1g of 1-hydroxycyclohexyl phenyl ketone, and 1g of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] into a reactor, heat to 60 degrees and stir for 20 minutes, cool to room temperature after complete dissolution, add 35g of aliphatic linear polyester urethane acrylate resin (DYMAX BR-582, USA), 10g of γ-trimethoxysilane modified acrylate polymer (X5-112, METAMORPHIC, USA), 1.5g of vinyltrimethoxysilane, and 100g of spherical silica powder (D50 = 5μm D100 = 24 μm), 0.06 g of fluorocarbon surfactant (Japan Morinaga FCS-005), high-speed dispersion at 3000 rpm for 5 min, ice water bath temperature control during the dispersion process to ensure that the system temperature does not exceed 35 degrees, after dispersion is completed, sealed and cooled to room temperature, 0.5 g of dibutyltin dilaurate was added, first stirred at 1000 rpm for 10 min, then the vacuum degree was adjusted to -0.08 MPa, the stirring speed was 500 rpm, and vacuum stirring and degassing were carried out for 10 min. All stirring processes were controlled by ice water bath temperature to ensure that the reactor temperature was not higher than 35 degrees. The product was filtered with a 200 mesh filter and vacuum packaged to obtain the finished glue.

[0041] Example 2

[0042] Accurately weigh 2g of hydroxyethyl acrylate, 15g of isobornyl methacrylate, 10g of isobornyl acrylate, 10g of acryloylmorpholine, 5g of acrylic acid, 0.6g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1g of 1-hydroxy-cyclohexyl phenyl ketone, and 1g of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] into a reactor, heat to 60 degrees and stir for 20 minutes, cool to room temperature after complete dissolution, and add 35g of aliphatic linear polyester urethane acrylate resin (DYMAX BR-582, USA), 10g of γ-trimethoxysilane modified acrylate polymer (X5-112, METAMORPHIC, USA), 1.5g of vinyltrimethoxysilane, and 100g of spherical silica powder (D50 = 5μm D100 = 24 μm), 0.06 g of fluorocarbon surfactant (Japan Morinaga FCS-005), high-speed dispersion at 3000 rpm for 5 min, ice water bath temperature control during the dispersion process to ensure that the system temperature does not exceed 35 degrees, after dispersion is completed, sealed and cooled to room temperature, 0.5 g of dibutyltin dilaurate was added, first stirred at 1000 rpm for 10 min, then the vacuum degree was adjusted to -0.08 MPa, the stirring speed was 500 rpm, and vacuum stirring and degassing were carried out for 10 min. All stirring processes were controlled by ice water bath temperature to ensure that the reactor temperature was not higher than 35 degrees. The product was filtered with a 200 mesh filter and vacuum packaged to obtain the finished glue.

[0043] Example 3

[0044] Accurately weigh 2g of hydroxyethyl acrylate, 15g of isobornyl methacrylate, 10g of isobornyl acrylate, 10g of acryloylmorpholine, 5g of acrylic acid, 0.6g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1g of 1-hydroxy-cyclohexyl phenyl ketone, and 1g of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were put into a reactor, heated to 60 degrees and stirred for 20 minutes. After complete dissolution, the mixture was cooled to room temperature, and 35g of aliphatic linear polyester urethane acrylate resin (DYMAX BR-582, USA), 10g of α-dimethoxysilane modified acrylate polymer (X5-115, METAMORPHIC, USA), 1.5g of vinyltrimethoxysilane, and 100g of spherical silica powder (D50 = 5μm) were added. D100 = 24 μm), 0.06 g of fluorocarbon surfactant (Japan Morinaga FCS-005), high-speed dispersion at 3000 rpm for 5 minutes, ice water bath temperature control during the dispersion process to ensure that the system temperature does not exceed 35 degrees, after dispersion is completed, seal and cool to room temperature, add 3-aminopropyltrimethoxysilane 3 g, first stir at 1000 rpm for 10 minutes, then adjust the vacuum degree to -0.08 MPa, stir at 500 rpm, and vacuum stir and deaerate for 10 minutes. All stirring processes are controlled by ice water bath temperature to ensure that the reactor temperature is not higher than 35 degrees. The product is filtered with a 200-mesh filter and vacuum packaged to obtain the finished glue.

[0045] Comparative Example 1

[0046] The specific implementation method is consistent with Example 1, except that the content of the main resin BR-582 is 45g, the content of X5-112 from METAMORPHIC (USA) is 0, and the moisture catalyst dibutyltin dilaurate is changed to peroxide TAPO to give the formula thermosetting ability. Other differences are the same;

[0047] Comparative Example 2

[0048] The specific implementation method is consistent with Example 1, except that the content of the main resin BR-582 is 40g, and the content of X5-112 produced by METAMORPHIC of the United States is 5g, and there are no other differences;

[0049] Comparative Example 3

[0050] The specific implementation method is consistent with Example 1, except that the content of the main resin BR-582 is 30g, and the content of X5-112 produced by METAMORPHIC, USA is 15g. Other differences are the same;

[0051] Comparative Example 4

[0052] The specific implementation method is consistent with Example 1, except that the content of the main resin BR-582 is 25g, and the content of X5-112 produced by METAMORPHIC, USA is 20g. Other differences are the same;

[0053] Comparative Example 5

[0054] The specific implementation method is the same as that of Example 2, except that the content of spherical silicon powder is increased to 200g, and there are no other differences;

[0055] Comparative Example 6

[0056] The specific implementation method is the same as that of Example 2, except that the content of spherical silicon powder is reduced to 50g, and there are no other differences;

[0057] Comparative Example 7

[0058] The specific implementation method is the same as that of Example 3, except that aminosilane is replaced with 3-aminopropyltriethoxysilane, and there are no other differences;

[0059] Comparative Example 8

[0060] The specific implementation method is consistent with Example 3, except that aminosilane is replaced with N-(β-aminoethyl)-γ-aminopropyltrimethyl(ethyl)oxysilane, and there are no other differences;

[0061] The glue properties obtained in Examples 1-3 and Comparative Examples 1-8 were tested and characterized by the following test methods.

[0062] Viscosity test, viscosity CPS indicates the flow performance of glue and the smoothness of dispensing, Brookfield viscosity tester.

[0063] Skin formation time, where the glue curing conditions are LED light 365nm, curing energy 10J / cm 2 , moisture curing conditions: 25 degrees 55% constant temperature and humidity box curing for 7 days.

[0064] Linear shrinkage is the curing shrinkage: the length change rate of the glue after UV and moisture are completely cured in a test mold with a length of 10 cm.

[0065] Modulus at room temperature: Modulus test: a 1 mm thick film was prepared and tested using a dynamic mechanical analysis (DMA) device after UV and moisture curing.

[0066] Thermal expansion coefficient test: Prepare a 5X5mm glue block and test it using a thermal mechanical analyzer (TMA) after UV and moisture curing.

[0067] The above experimental test results are shown in Table 1:

[0068] Table 1

[0069]

[0070]

[0071] From Comparative Example 1, it can be seen that compared with traditional UV thermosetting glue, the UV moisture dual curing glue of the present invention can greatly reduce the shrinkage rate of the glue after curing. From Comparative Examples 2 to 4, it can be seen that by increasing the proportion of moisture components in the system, the linear shrinkage rate after curing shows a downward trend. Comparative Examples 7 and 8 show that the speed of moisture curing has a relatively obvious impact on the curing shrinkage. The faster the moisture curing, the greater the shrinkage.

[0072] In summary, compared with traditional UV thermosetting glue, the UV moisture dual curing glue of the present invention has a shrinkage rate of less than 1% after curing, a modulus at room temperature greater than 500 MPa, and a thermal expansion coefficient less than 50 ppm, which can meet the positioning and alignment glue requirements of most electronic consumer fields.

[0073] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A low shrinkage UV moisture dual curing adhesive, characterized in that: The invention comprises the following components in parts by weight: 10-20 parts of polyurethane acrylate resin, 10-20 parts of silane-terminated modified polyurethane acrylate polymer, 5-20 parts of reactive acrylate monomer, 0.5-2 parts of photoinitiator, 0.5-1 parts of water scavenger, 0.5-2 parts of catalyst, 20-50 parts of filler, 0-2 parts of fumed silica, 0-2 parts of antioxidant and 0.5-1 parts of additives.

2. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The polyurethane acrylate resin is any one of polycarbonate acrylate, polybutadiene acrylate, polyether polyurethane acrylate, and polyester polyurethane acrylate.

3. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The silane-terminated modified polyurethane acrylate polymer is a mixture of any one or more of α-dimethoxysilane-modified polyurethane acrylate polymer and γ-trimethoxysilane-modified acrylate polymer.

4. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The reactive acrylate monomer includes one or more mixtures of soft monomers and hard monomers. The soft monomer is one or more mixtures of 2(2-ethoxyethoxy)ethyl acrylate, isooctyl acrylate, isodecyl acrylate, tetrahydrofuran acrylate, hydroxyethyl acrylate, and dodecyl acrylate. The hard monomer is one or more mixtures of isobornyl acrylate, N,N-2-methylacrylamide, acryloylmorpholine, acrylic acid, N-vinyl pyrrolidone, and 3,3,5-trimethylcyclohexane acrylate.

5. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The photoinitiator is one or a mixture of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphosphonic acid ethyl ester, 4-dimethylamino-benzoic acid ethyl ester, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide.

6. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The dewatering agent is a mixture of any one or more of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(β-methoxyethoxy)silane.

7. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The catalyst is one of dibutyltin dilaurate, tetrabutylphthalate, and aminosilane, or a mixture of several of them.

8. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The filler is one or a mixture of silicon micropowder, aluminum oxide, light calcium carbonate, and fumed silicon dioxide.

9. The low shrinkage UV moisture dual curing adhesive according to claim 1, characterized in that: The antioxidant is one of butyl (3,5-di-tert-butyl-4-hydroxybenzyl) malonate bis (1,2,2,6,6-pentamethyl-4-piperidinyl), 1,5,8,12-tetrakis [4,6-bis (N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino) -1,3,5-triazine-2-yl] -1,5,8,12-tetraazadodecane, pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis (3-laurylthiopropionate) or a mixture thereof, and the additive is a fluorocarbon modified surfactant.

10. A method for preparing a low shrinkage UV moisture dual curing adhesive, for preparing the low shrinkage UV moisture dual curing adhesive according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Pretreatment: All monomers are filtered through molecular sieves to remove water from the system, and the water content is tested by titration with a Karl Fischer moisture meter to be less than 0.1%; the filler needs to be baked to 120 degrees to ensure complete drying; Step 2: Add photoinitiator, light stabilizer and reactive monomer according to the above weight ratio, heat to 45-60 degrees and stir until completely dissolved; Step 3: After cooling the liquid from step 2 to room temperature, add polyurethane acrylate resin, silane modified polymer, water scavenger, filler, and additives, and disperse at 3000 rpm for 10-30 minutes; Step 4: After cooling the mixture in step 2 to room temperature, add the moisture catalyst and stir at low speed for 5-10 minutes in an ice-water bath to mix evenly. During the stirring period, control the system temperature not to exceed 30 degrees. Step 5: Vacuum stirring and degassing for 10 minutes, controlling the stirring speed to below 500 rpm to ensure that stirring does not generate heat; Step 6: Filter the product of step 4 through a 200-mesh filter to obtain a low-curing shrinkage UV-moisture dual-curing adhesive.

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