Optical adhesive as well as preparation method and application thereof

Abstract

The invention relates to an optical adhesive as well as a preparation method and application thereof. The optical adhesive is prepared from the following raw materials in percentage by weight: 40-70 parts of acrylate soft monomer; 10 to 30 parts of an acrylate hard monomer; 20 to 40 parts of a hydroxyl acrylate functional monomer; and 0.01 to 2 parts of a photoinitiator. According to the invention, the acrylate soft monomer and the acrylate hard monomer are compounded for use, and meanwhile, the hydroxyl acrylate functional monomer and the photoinitiator are matched, so that the adhesive force of the optical adhesive can be increased, the water vapor transmittance can be reduced, and the optical adhesive has better physical properties, rheological properties and aging resistance. Meanwhile, by adjusting the proportion of soft and hard monomers and the proportion of hydrophilic group hydroxyl in the formula of the optical adhesive, the requirement for reducing the water vapor transmission rate of the optical adhesive is met, the water vapor transmission rate can be maintained at 60g / m < 2 > / d-70g / m < 2 > / d in some embodiments, invasion and erosion of water vapor can be effectively prevented, and the stability and performance of an optical adhesive system are ensured.

Description

Technical Field

[0001] The present application relates to the technical field of optical adhesives, and in particular to an optical adhesive and a preparation method and application thereof. Background Art

[0002] Optically clear adhesive (OCA) is a special adhesive used to bond transparent optical components. It is colorless and transparent, has a light transmittance of more than 90%, good bonding strength, can be cured at room temperature or medium temperature, and has the characteristics of small curing shrinkage. In the full bonding technology, OCA glue has significant advantages: 1. Reduce glare, reduce the loss of light emitted by industrial displays, increase the brightness of industrial displays and provide high transmittance, and reduce energy consumption; 2. Increase contrast, especially under strong light; 3. Surface connection has higher strength; 4. Can effectively avoid Newton rings; 5. The product surface is smoother; 6. No borders, expanding the visible area; Therefore, in the full bonding process, OCA glue has a wide range of applications.

[0003] Ordinary OCAs are prone to water vapor infiltration during normal use, especially when exposed to bad weather. Once water vapor enters the optical film, it will have many negative effects on its performance. First, water vapor will change the refractive index inside the optical film, resulting in a decline in optical performance, such as image blur, color distortion, and reduced brightness. Secondly, the penetration and diffusion of water vapor will cause changes in stress distribution, which may cause deformation or cracking of optical components, and destroy the stability and precision of the optical system. In addition, water vapor will also destroy the adhesion interface between the optical film and the optical component, weaken the adhesion performance, and may cause the component to fall off or loosen. Finally, water vapor will accelerate the aging process of the optical film and shorten the service life of the optical system. Summary of the invention

[0004] Based on this, it is necessary to provide an optical adhesive and a preparation method and application thereof, wherein the optical adhesive has good physical properties, rheological properties and aging resistance, and can significantly reduce water vapor permeability.

[0005] The technical solution of this application is as follows:

[0006] In a first aspect of the present invention, an optical adhesive is provided, wherein the raw materials thereof include the following components in parts by weight:

[0007] 40-70 parts of acrylic soft monomer;

[0008] 10-30 parts of acrylic acid hard monomer;

[0009] 20-40 parts of hydroxy acrylate functional monomer;

[0010] Photoinitiator 0.01-2 parts.

[0011] In one embodiment, the acrylic soft monomer includes at least one of n-butyl acrylate, tert-butyl acrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate and lauryl methacrylate; and / or

[0012] The acrylic acid ester hard monomer includes at least one of n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, methyl methacrylate, ethyl methacrylate and methyl acrylate.

[0013] In one embodiment, the hydroxyacrylate functional monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate.

[0014] In one embodiment, the photoinitiator includes at least one of a benzil photoinitiator, an alkyl phenone photoinitiator, an acylphosphine oxide photoinitiator, a benzophenone photoinitiator and a thioxanthone photoinitiator;

[0015] Optionally, the photoinitiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and methyl benzoylformate.

[0016] In one embodiment, the raw materials of the optical adhesive further include the following components in proportion by weight:

[0017] Cross-linking agent 0.1-5 parts; chain transfer agent 0.01-2 parts; coupling agent 0.01-2 parts; antioxidant 0.01-2 parts.

[0018] In one embodiment, the crosslinking agent includes at least one of HS-268 special acrylate, benzoyl peroxide, dibenzoyl peroxide, 1,6-ethylene glycol diacrylate, dipentaerythritol pentapropionate, and aliphatic polyurethane acrylate; and / or

[0019] The chain transfer agent includes at least one of n-dodecyl mercaptan and mercaptoethanol.

[0020] In one embodiment, the coupling agent includes a silane coupling agent; optionally, the silane coupling agent includes one or more of γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and vinyltri(β-methoxyethoxy)silane; and / or

[0021] The antioxidant includes one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl)phosphite, 2,6-di-tert-butyl-4-methylphenol and dilauryl thiodipropionate.

[0022] A second aspect of the present invention provides a method for preparing the optical adhesive as described above, comprising the following steps:

[0023] Prepolymerizing part of the acrylic soft monomer, the acrylic hard monomer, the hydroxy acrylic functional monomer and the photoinitiator to prepare a prepolymer;

[0024] The remaining acrylate hard monomer, acrylate soft monomer and photoinitiator are added to the prepolymer to carry out polymerization reaction.

[0025] In one embodiment, the polymerization reaction satisfies at least one of the following conditions:

[0026] (1) Carry out under nitrogen atmosphere;

[0027] (2) The viscosity of the prepolymer is 200cps-500cps.

[0028] A third aspect of the present invention provides an optical adhesive as described above, or an optical adhesive made according to the method for preparing the optical adhesive as described above, for use in a full bonding process.

[0029] Compared with the prior art, this application has the following beneficial effects:

[0030] The present application uses a combination of acrylate soft monomers and acrylate hard monomers, and is combined with hydroxy acrylate functional monomers and photoinitiators to increase the adhesion of the optical adhesive and reduce the water vapor transmission rate, so that it has better physical properties, rheological properties and aging resistance. At the same time, the present application achieves the requirement of reducing the water vapor transmission rate of the optical adhesive by adjusting the ratio of soft and hard monomers and the ratio of hydrophilic group hydroxyl groups in the formula of the optical adhesive. In some embodiments, it can be maintained at 60g / m 2 / d-70g / m 2 / d, which can effectively prevent the intrusion and erosion of water vapor and ensure the stability and performance of the optical adhesive system. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0033] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0034] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0035] Herein, the optional scope of "and / or", "or / and", and "and / or" includes any one of two or more relevant listed items, and also includes any and all combinations of the relevant listed items, wherein said any and all combinations include any two relevant listed items, any more relevant listed items, or a combination of all relevant listed items. (It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions that are all connected by "logical AND", and also undoubtedly includes technical solutions that are all connected by "logical OR". For example, "A and / or B" includes three parallel solutions of A, B and A+B. For another example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, technical solutions that are all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, a combination of any two or any three of A, B, C, and D, and also includes a combination of four items of A, B, C, and D (that is, a technical solution that is all connected by "logical AND").)

[0036] Herein, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0037] Herein, "first aspect", "second aspect", "third aspect", "fourth aspect", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. In addition, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0038] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0039] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, and any upper limit can be combined with any other upper limit to form an undefined range. In addition, each separately disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an undefined range. The use of numerical ranges represented by endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0040] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0041] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0042] The temperature parameters in this application, unless otherwise specified, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±2°C, ±1°C, ±0.5°C, ±0.4°C, ±0.3°C, ±0.2°C, and ±0.1°C are allowed. Normal temperature or room temperature in this application refers to no temperature control operation, generally 4°C~35°C, preferably 20±5°C.

[0043] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0044] In a first aspect of the present invention, an optical adhesive is provided, wherein the raw materials thereof include the following components in parts by weight:

[0045] 40-70 parts of acrylic soft monomer;

[0046] 10-30 parts of acrylic acid hard monomer;

[0047] 20-40 parts of hydroxy acrylate functional monomer;

[0048] Photoinitiator 0.01-2 parts.

[0049] In some examples, the acrylic soft monomer includes at least one of n-butyl acrylate, tert-butyl acrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate and lauryl methacrylate.

[0050] In some examples, the acrylic hard monomer includes at least one of n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, methyl methacrylate, ethyl methacrylate and methyl acrylate.

[0051] In some examples, the hydroxyacrylate functional monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate.

[0052] In some examples, the photoinitiator includes at least one of a benzil-based photoinitiator, an alkylphenone-based photoinitiator, an acylphosphine oxide-based photoinitiator, a benzophenone-based photoinitiator, and a thioxanthone-based photoinitiator.

[0053] In some examples, the photoinitiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and methyl benzoylformate.

[0054] In some of the examples, the photoinitiator models include photoinitiator 1173, photoinitiator 184, photoinitiator 651, photoinitiator 907, photoinitiator 369, photoinitiator 1490, and photoinitiator 1700.

[0055] In some examples, the raw materials of the optical adhesive further include the following components by weight:

[0056] Cross-linking agent 0.1-5 parts; chain transfer agent 0.01-2 parts; coupling agent 0.01-2 parts; antioxidant 0.01-2 parts.

[0057] In some examples, the crosslinking agent includes at least one of HS-268 special acrylate, benzoyl peroxide, dibenzoyl peroxide, 1,6-ethylene glycol diacrylate, dipentaerythritol pentapropionate, and aliphatic polyurethane acrylate.

[0058] In some examples, the chain transfer agent includes at least one of n-dodecyl mercaptan and mercaptoethanol.

[0059] Furthermore, in the raw materials of the optical adhesive, the weight percentage of the chain transfer agent is 0.01-1. In the process of preparing the optical adhesive, the amount of the chain transfer agent should be reasonably controlled. If it is excessive, it will lead to too low hardness, too soft, difficult to bond, and poor bonding effect.

[0060] In some examples, the coupling agent includes a silane coupling agent.

[0061] In some examples, the silane coupling agent includes one or more of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and vinyltri(β-methoxyethoxy)silane.

[0062] In some examples, the antioxidant includes one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl)phosphite, 2,6-di-tert-butyl-4-methylphenol and dilauryl thiodipropionate.

[0063] In some of the examples, the antioxidant types include antioxidant 1010, antioxidant 168, antioxidant BHT and antioxidant DLTP.

[0064] A second aspect of the present invention provides a method for preparing the optical adhesive as described above, comprising the following steps:

[0065] Prepolymerizing part of the acrylic soft monomer, the acrylic hard monomer, the hydroxy acrylic functional monomer and the photoinitiator to prepare a prepolymer;

[0066] The remaining acrylate hard monomer, acrylate soft monomer and photoinitiator are added to the prepolymer to carry out polymerization reaction.

[0067] In some of the examples, the step of performing the polymerization reaction includes adding the remaining acrylate hard monomer, acrylate soft monomer and photoinitiator, as well as a crosslinking agent, a coupling agent, a chain transfer agent and an antioxidant to the prepolymer.

[0068] The small material comprises a mixture of the acrylic ester hard monomer, the acrylic ester soft monomer, a crosslinking agent, a coupling agent, a chain transfer agent, an antioxidant and a photoinitiator.

[0069] In some examples, the polymerization temperature is 5° C. to 20° C. It is understood that the polymerization temperature includes but is not limited to 5° C., 8° C., 10° C., 12° C., 14° C., 16° C., 18° C., and 20° C.

[0070] In some of these examples, the polymerization reaction was carried out under a nitrogen atmosphere.

[0071] In some examples, the viscosity of the prepolymer is 200cps-500cps. It can be understood that the viscosity of the prepolymer includes but is not limited to 200cps, 250cps, 300cps, 350cps, 400cps, 450cps, and 500cps.

[0072] A third aspect of the present invention provides an optical adhesive as described above, or an optical adhesive made according to the method for preparing the optical adhesive as described above, for use in a full bonding process.

[0073] The following is further described in conjunction with specific embodiments. The raw materials involved in the following specific embodiments, unless otherwise specified, can all be commercially available; the instruments used, unless otherwise specified, can all be commercially available; the processes involved, unless otherwise specified, are all routinely selected by those skilled in the art.

[0074] As shown in Table 1, the abbreviations of some raw materials used in the examples and comparative examples are as follows:

[0075] BA: n-butyl acrylate;

[0076] EHA: isooctyl acrylate;

[0077] CHA: cyclohexyl acrylate;

[0078] HEA: Hydroxyethyl acrylate;

[0079] HBA: Hydroxybutyl acrylate;

[0080] IBOA: isobornyl acrylate;

[0081] BMA: n-butyl methacrylate;

[0082] HDDA: 1,6-ethylene glycol diacrylate;

[0083] KH560: silane coupling agent, γ-glycidyloxypropyltrimethoxysilane;

[0084] CN8888NS: polyurethane acrylic resin;

[0085] Antioxidant 1010: quaternary ammonium salt antistatic agent, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

[0086] Photoinitiator 184: 1-hydroxycyclohexyl phenyl ketone;

[0087] Photoinitiator 651: 2,2-dimethoxy-2-phenylacetophenone.

[0088] The following are specific embodiments.

[0089] Example 1

[0090] Polymerization of prepolymers

[0091] 60 parts of isooctyl acrylate (EHA), 10 parts of cyclohexyl acrylate (CHA), 10 parts of isobornyl acrylate (IBOA), 20 parts of hydroxyethyl acrylate (HEA) and 0.1 parts of photoinitiator 184 (1-hydroxycyclohexyl phenyl ketone) are added into a reactor, and nitrogen is introduced. After the oxygen in the reactor is completely replaced by nitrogen, the ultraviolet lamp is turned on to carry out polymerization reaction. When the temperature rises by 10°C, the reaction is stopped to obtain a prepolymer (the viscosity of the prepolymer is about 200cps-500cps).

[0092] Preparation of OCA optical adhesive film with low water vapor transmission rate

[0093] Add 4 parts of n-butyl methacrylate (BMA), 10 parts of isooctyl acrylate (EHA), 1.5 parts of crosslinking agent CN8888NS, 0.03 parts of chain transfer agent n-dodecyl mercaptan, 10 parts of antioxidant 1010, 0.3 parts of silane coupling agent KH560, and 0.1 parts of photoinitiator 651 (2,2-dimethoxy-2-phenylacetophenone) to the above prepolymer, mix the composition evenly, degas with a degassing machine, and then apply the glue composition to a silicone resin treated polyethylene terephthalate (PET) release film with a thickness of 250 microns, cover it with another layer of polyethylene terephthalate (PET) release film, turn on the ultraviolet lamp (ultraviolet wavelength is 300nm-400nm), and irradiate with an intensity of 3mw / cm 2 The total energy of the UV light is 2000mj / cm 2 , an optical adhesive film with a thickness of 250 μm was obtained.

[0094] Example 2

[0095] The preparation method of Example 2 is substantially the same as that of Example 1, except that 0.06 parts of n-dodecyl mercaptan, a mid-chain transfer agent, is added to the small material.

[0096] Example 3

[0097] The preparation method of Example 3 is basically the same as that of Example 1, except that: 15 parts of acrylic ester soft monomer (isooctyl acrylate) are added to the small material; and 0.06 parts of chain transfer agent (n-dodecyl mercaptan) are added to the small material.

[0098] Example 4

[0099] The preparation method of Example 4 is basically the same as the preparation method of Example 1, except that: the acrylic ester soft monomer (isooctyl acrylate) in the prepolymer is 56 parts; the hard monomer (isobornyl acrylate) in the prepolymer is 14 parts; and the chain transfer agent (n-dodecyl mercaptan) is not added to the small material.

[0100] Comparative Example 1

[0101] The preparation method of Comparative Example 1 is basically the same as the preparation method of Example 1, except that: the functional monomer hydroxy acrylate (hydroxyethyl acrylate) in the prepolymer is replaced with a functional monomer hydroxy acrylate (hydroxybutyl acrylate), and the amount is 20 parts; the acrylate soft monomer (isooctyl acrylate) in the prepolymer is 56 parts; the hard monomer (isobornyl acrylate) in the prepolymer is 14 parts; the macromolecular crosslinking agent added in the small material is replaced with a small molecule crosslinking agent (1,6-ethylene glycol diacrylate), and the amount is 0.2 parts; the chain transfer agent (n-dodecyl mercaptan) added in the small material is 0.04 parts.

[0102] Comparative Example 2

[0103] The preparation method of Comparative Example 2 is basically the same as the preparation method of Example 1, except that: the functional monomer hydroxy acrylate (hydroxyethyl acrylate) in the prepolymer is replaced with a functional monomer hydroxy acrylate (hydroxybutyl acrylate), and the amount is 20 parts; the acrylate soft monomer (isooctyl acrylate) in the prepolymer is 56 parts; the hard monomer (isobornyl acrylate) in the prepolymer is 14 parts; the macromolecular crosslinking agent added in the small material is replaced with a small molecule crosslinking agent (1,6-ethylene glycol diacrylate), and the amount is 0.15 parts; the chain transfer agent: n-dodecyl mercaptan is not added to the small material.

[0104] Comparative Example 3

[0105] The preparation method of Comparative Example 2 is basically the same as the preparation method of Example 1, except that: the functional monomer hydroxy acrylate (hydroxyethyl acrylate) in the prepolymer is replaced with 20 parts of the functional monomer hydroxy acrylate (hydroxybutyl acrylate); the acrylate soft monomer (isooctyl acrylate) in the prepolymer is 56 parts; the hard monomer (isobornyl acrylate) in the prepolymer is 14 parts; and no chain transfer agent (n-dodecyl mercaptan) is added to the small material.

[0106] The raw materials for preparing the optical adhesive in Examples 1 to 4 and Comparative Examples 1 to 3 are listed in Table 1:

[0107] Table 1

[0108]

[0109] The optical adhesives prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to performance tests such as hardness, adhesion, tensile strength, rheological test, optical test and weather resistance test. The test results are shown in Table 2 below.

[0110] Among them, the test methods for each performance test item are:

[0111] Hardness test

[0112] The oca glue was stacked into a thickness of 2000 microns, cut into a sample size of 5 cm × 5 cm, and placed on an IRHD hardness tester for hardness testing;

[0113] Adhesion test

[0114] Sample preparation method: This test measures the force required to peel off the tape at an angle of 180 degrees. The specific test method is as follows: Before the test, wipe the test glass plate with ethanol three times, transfer one side of the prepared optical film to 75 micron PET, cut the sample strip into a width of 25mm, stick it on the glass plate, roll it with a 2kg roller twice, and let it stand for 20 minutes in a controlled environment (temperature 23 degrees, humidity 50%), and then use a tensile test peel force machine to test the adhesion;

[0115] Tensile strength test

[0116] Sample preparation method: Cut the sample into 2.5cm×5.5cm strips, remove the release films on both sides, and use a tensile test peel force machine to test the elongation at break, maximum force, and deformation at maximum force;

[0117] Rheological testing

[0118] Sample preparation method: stack the sample into a thickness of 800 microns, place it on a suitable jig, make a sample, and place it on a dynamic mechanical analyzer (DMA) to test its storage modulus at room temperature 25°C and high temperature 85°C;

[0119] Optical testing

[0120] The quartz glass sheet was wiped with alcohol three times, and then the OCA adhesive layer was attached to the quartz glass sheet. According to the ASTM D1009 standard, the transmittance and haze of the adhesive layer were measured using a color haze meter.

[0121] Heat and humidity accelerated aging test

[0122] Sample preparation method: Cut the sample into 9cm×9cm, stick it between two layers of 9cm×9cm glass, use a high-pressure degassing machine for degassing (45℃, 5kg, 30min), let it stand for 2 hours after degassing, and then put it in an oven at 105℃, double 85 (temperature 85℃, humidity 85%), -45℃, and hot and cold shock (-45℃~95℃). After 1000h, observe the appearance of the bonded sample and record whether there are bubbles, cracks, yellowing and other abnormal phenomena (no abnormality is recorded as ◎, slight abnormality is recorded as ○, and abnormality is recorded as NG).

[0123] Table 2

[0124]

[0125] As can be seen from Table 2 above, the optical adhesives prepared in Examples 1 to 4 all have good physical properties, rheological properties and aging resistance, and the water vapor transmission rate is maintained at 60-70 g / m 2 / d, which is lower than that of comparative examples 1 to 3, achieving the requirement of reducing the water vapor transmission rate of OCA, and having excellent performance. Compared with traditional OCA, it improves the product's resistance to high temperature and humidity, effectively solving the problem of whitening caused by excessive water vapor and the problem of insufficient product adhesion under high temperature environment.

[0126] Within the range of the amount of each component raw material, Examples 1 to 4 have relatively excellent and suitable performance, and their hardness is moderate. They will not affect the bonding quality due to uneven bonding and bubbles caused by excessive hardness, nor will they be difficult to maintain a stable shape and position during the bonding process due to excessive hardness, thereby increasing the difficulty and cost of bonding; their high-temperature modulus is relatively high, which means that under high-temperature environments, the bonding effect will not produce bubbles and cracks; their adhesion is relatively high, which means that they can still maintain good adhesion when used in high-temperature environments; their water vapor permeability is low, which means that under high-temperature and high-humidity environments, the OCA will not produce whitening and fogging in the surface; their tensile properties and optical properties are also excellent; the embodiments.

[0127] Compared with Example 1, in Comparative Example 1, hydroxyethyl acrylate in the prepolymer is replaced by hydroxybutyl acrylate, and the ratio of soft and hard monomers is adjusted, and the cross-linking agent in the small material is replaced by HDDA, and its elongation at break is greatly reduced, resulting in poor tensile properties, and the hydroxyl content is reduced, resulting in a large water vapor permeability, and OCA causes whitening and fogging on the surface under high temperature and high humidity environment; Compared with Example 1, Comparative Example 2 reduces the amount of cross-linking agent on the basis of Comparative Example 1, and does not add a chain transfer agent, and its tensile properties are not significantly improved, and OCA causes whitening and fogging on the surface under high temperature and high humidity environment; Compared with Example 1, Comparative Example 3 replaces the cross-linking agent with polyurethane acrylic resin on the basis of Comparative Example 2, and its elongation at break is significantly improved, and the tensile properties are improved, but OCA causes whitening and fogging on the surface under high temperature and high humidity environment.

[0128] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims, and the description may be used to interpret the content of the claims.

Claims

1. An optical adhesive, characterized in that: The raw materials include the following components by weight: 40-70 parts of acrylic soft monomer; 10-30 parts of acrylic acid hard monomer; 20-40 parts of hydroxy acrylate functional monomer; Photoinitiator 0.01-2 parts.

2. The optical adhesive according to claim 1, characterized in that: The acrylic soft monomer includes at least one of n-butyl acrylate, tert-butyl acrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate and lauryl methacrylate; and / or The acrylic acid ester hard monomer includes at least one of n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, methyl methacrylate, ethyl methacrylate and methyl acrylate.

3. The optical adhesive according to claim 1, characterized in that: The hydroxy acrylate functional monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate.

4. The optical adhesive according to claim 1, characterized in that: The photoinitiator includes at least one of a benzil photoinitiator, an alkyl phenone photoinitiator, an acylphosphine oxide photoinitiator, a benzophenone photoinitiator and a thioxanthone photoinitiator; Optionally, the photoinitiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and methyl benzoylformate.

5. The optical adhesive according to any one of claims 1 to 4, characterized in that: The raw materials also include the following components by weight: Cross-linking agent 0.1-5 parts; chain transfer agent 0.01-2 parts; coupling agent 0.01-2 parts; antioxidant 0.01-2 parts.

6. The optical adhesive according to claim 5, characterized in that: The crosslinking agent includes at least one of HS-268 special acrylate, benzoyl peroxide, dibenzoyl peroxide, 1,6-ethylene glycol diacrylate, dipentaerythritol pentapropionate, and aliphatic polyurethane acrylate; and / or The chain transfer agent includes at least one of n-dodecyl mercaptan and mercaptoethanol.

7. The optical adhesive according to claim 5, characterized in that: The coupling agent includes a silane coupling agent; optionally, the silane coupling agent includes one or more of γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and vinyltri(β-methoxyethoxy)silane; and / or The antioxidant includes one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl)phosphite, 2,6-di-tert-butyl-4-methylphenol and dilauryl thiodipropionate.

8. A method for preparing an optical adhesive according to any one of claims 1 to 7, characterized in that: The following steps are involved: Prepolymerizing part of the acrylic soft monomer, the acrylic hard monomer, the hydroxy acrylic functional monomer and the photoinitiator to prepare a prepolymer; The remaining acrylate hard monomer, acrylate soft monomer and photoinitiator are added to the prepolymer to carry out polymerization reaction.

9. The method for preparing the optical adhesive according to claim 8, characterized in that: The polymerization reaction satisfies at least one of the following conditions: (1) Carry out under nitrogen atmosphere; (2) The viscosity of the prepolymer is 200 cps-500 cps.

10. Use of the optical adhesive according to any one of claims 1 to 7, or the optical adhesive prepared according to the preparation method of the optical adhesive according to any one of claims 8 to 9 in a full bonding process.

Images