TW202235464A - Optical adhesive agent, optical adhesive layer and the method for forming the same, and optical laminate - Google Patents

Abstract

An optical adhesive agent includes an acrylate oligomer and a thermal initiator. The acrylate oligomer is formed by copolymerizing a first acrylate monomer (A) having a polysiloxane structure and a second acrylate monomer (B). An optical adhesive layer including the optical adhesive agent and the method for forming the same are also provided. An optical laminate including a substrate, a polarizer, and the optical adhesive layer disposed betweenthere is also provided.

Description

Optical adhesive, optical adhesive layer and method for forming same, and optical laminate

The present disclosure relates to an optical adhesive, in particular to an optical adhesive with a polysilyl ether structure.

The optically clear adhesive (Optically Clear Adhesive) provided between the touch panel and the module in the electronic device is used to increase clarity, reduce light scattering, and produce clearer images. However, the water content of the optically clear adhesive will affect the degree of yellowing of the polarizer after the high temperature reliability test.

An embodiment of the present invention provides an optical adhesive, which includes an acrylate oligomer and a thermal initiator. The acrylate oligomer is formed by copolymerizing (A) a first acrylate monomer and (B) a second acrylate monomer. (A) The first acrylate monomer has a polysilyl ether structure.

An embodiment of the present invention also provides an optical adhesive layer, which includes the above-mentioned optical adhesive, a photoinitiator, and a crosslinking agent.

An embodiment of the present invention also provides an optical laminate, which includes a substrate, a polarizer, and the above-mentioned adhesive layer disposed between the substrate and the polarizer.

Embodiments of the present invention also provide a method for forming an optical adhesive layer, which includes preparing an optical adhesive; mixing the optical adhesive with a photoinitiator and a crosslinking agent to form a mixed solution; coating the mixed solution on a and irradiating the mixed solution with light to obtain an optical adhesive layer. The step of preparing the optical adhesive includes: an acrylate oligomer formed by copolymerizing (A) the first acrylate monomer and (B) the second acrylate monomer with a thermal initiator, wherein (A) The first acrylate monomer has a polysilicon ether structure.

Various embodiments or examples are provided below for implementing different elements of the invention. Where the description mentions that the first component is formed on the second component, it may include an embodiment where the first and second components are in direct contact, and may also include an additional component formed between the first and second components such that the first An embodiment where the first and second parts are not in direct contact. In addition, the embodiments of the present invention may use repeated reference numerals in many instances. These repetitions are for simplicity and clarity only and do not imply a specific relationship between the various embodiments and/or configurations discussed.

Furthermore, spatially related terms such as "front", "back", "above", "below", "above", "below" and similar In addition to the orientation shown in the formula, it also includes different orientations of the device in use or operation. When the device is turned to another orientation (rotated 90 degrees or otherwise), the spatially relative descriptions used herein can also be read in terms of the rotated orientation.

Here, the terms "about", "approximately" and "approximately" usually mean within 20%, preferably within 10%, and more preferably within 5%, or within 3% of a given value or range. Within %, or within 2%, or within 1%, or within 0.5%. It should be noted that the quantities provided in the instructions are approximate quantities, that is, in the absence of specific descriptions of "about", "approximately" and "approximately", "approximately", "approximately" and "approximately" may still be implied "probably" meaning.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It can be understood that these terms, such as those defined in commonly used dictionaries, should be interpreted as having meanings consistent with the background or context of the related technology and the present disclosure, and should not be interpreted in an idealized or overly formal manner, Unless otherwise specified in the disclosed embodiments.

Specifically, the moisture contained in the adhesive will intrude into the polarizer of the panel module after the high-temperature reliability test, causing the polarizers of the polarizer to undergo polyolefination and yellowing.

In order to improve the above problems, the polarizer is usually preheated (PRE-BAKING) before bonding to remove the moisture contained in the polarizer. However, although this method can effectively remove the moisture contained in the polarizing plate, it still cannot remove the moisture contained in the optically clear adhesive. Therefore, the industry still needs to improve optically clear adhesives to overcome the problem of yellowing.

The optical adhesive provided by the embodiment of the present invention includes (A) the first acrylate monomer having a polysilyl ether structure, so as to reduce the water content in the optical adhesive, so as to reduce the distribution coefficient of water. And by the specific content of (A) the first acrylate monomer of the polysilyl ether structure, the haze of the optical adhesive layer can be reduced. In addition, without affecting the adhesion, the acrylate oligomer does not have hydroxyl groups, which can further reduce the water content.

First, please refer to Figure 1. The optical sheet 10 in FIG. 1 includes a substrate 100 and an optical adhesive layer 200 thereon.

In some embodiments, the substrate 100 is a release film. The release film is used to temporarily protect the optical adhesive layer 200 from damage or contamination. In some embodiments, the material of the release film can be polyethylene terephthalate (polyethylene terephthalate, PET), polybutylene terephthalate, polycarbonate, polyarylate, polyester resin, Olefin resin, cellulose acetate resin, acrylic resin, polyethylene (PE), polypropylene (PP), cycloolefin resin, polysiloxane, or a combination thereof.

In some embodiments, the optical adhesive layer 200 can be obtained by coating a mixed solution of an optical adhesive mixed with a photoinitiator and a crosslinking agent on the substrate 100 and then irradiating light. The composition of the mixed solution for forming the optical adhesive layer 200 will be described in detail below.

[Optical Adhesive]

In some embodiments, the optical adhesive includes an acrylate oligomer and a thermal initiator. In some embodiments, the optical adhesive is an optically clear adhesive (Optically Clear Adhesive).

[Acrylate Oligomer]

In some embodiments, the acrylate oligomer is formed by copolymerizing (A) a first acrylate monomer and (B) a second acrylate monomer with a thermal initiator. It should be noted that (A) the first acrylate monomer and (B) the second acrylate monomer are different acrylate monomers.

In one embodiment, the weight average molecular weight of the acrylate oligomer is between 200,000-1,000,000. In another embodiment, the weight average molecular weight of the acrylate oligomer is between 400,000-800,000.

[(A) first acrylate monomer]

In some embodiments, (A) the first acrylate monomer has a polysilyl ether structure. Since the polysiloxane structure is hydrophobic, the water content of the optical adhesive layer 200 can be reduced in consideration of cost.

； 其中R ₁、R ₄、R ₅各自獨立地為氫原子、或C1-C5烷基； R ₂為C1-C5伸烷基或單鍵； R ₃為C1-C5烷基； n為5-150之整數，例如10-100。 In some embodiments, (A) the first acrylate monomer has the structure shown in the following chemical formula 1: [chemical formula 1]

; wherein R ₁ , R ₄ , and R ₅ are each independently a hydrogen atom, or a C1-C5 alkyl group; R ₂ is a C1-C5 alkylene group or a single bond; R ₃ is a C1-C5 alkyl group; n is 5- An integer of 150, such as 10-100.

In some embodiments, the (A) first acrylate monomer may include a combination of two or more structures having the above Chemical Formula 1. For example, n is the same and R ₁ -R ₅ are different or n is different and R ₁ -R ₅ are the same.

； 其中n為5-150之整數，例如10-100。 In some preferred embodiments, (A) the first acrylate monomer has the structure shown in the following chemical formula 2: [chemical formula 2]

; wherein n is an integer of 5-150, such as 10-100.

In some embodiments, the (A) first acrylate monomer includes at least two acrylate monomers with different degrees of polysiloxane polymerization. For example, mix n=10 and n=100 acrylate monomers with two degrees of polymerization to adjust the compatibility in acrylic resin. In some embodiments, (A) the first acrylate monomer does not have a hydroxyl group, which can further reduce the water content of the optical adhesive layer 200 .

In one embodiment, the weight average molecular weight of (A) the first acrylate monomer is between 2,000-8,000. In another embodiment, the weight average molecular weight of (A) the first acrylate monomer is between 4,000-6,000.

[(B) second acrylate monomer]

(B) The second acrylate monomer is a polysiloxane-free monomer. In some embodiments, (B) the second acrylate monomer includes at least one compound selected from the group consisting of (meth)acrylates with alkyl groups, (meth)acrylic acid esters with alkoxy groups Esters, (meth)acrylates with halogen atoms, (meth)acrylates with alicyclic groups, (meth)acrylates with aryl groups, (meth)acrylates with aryloxy groups, and the above combination. In some embodiments, the carbon number of the alkyl group, aryl group, aryloxy group, and alicyclic group is not particularly limited, preferably 2-20. It should be noted that in this article, (meth)acrylate refers to any one of acrylate or methacrylate, and the meanings of "(meth)" appearing in the rest can be deduced in the same way.

The (meth)acrylate which has an alkyl group may contain the (meth)acrylate of a linear or branched alkyl group.

The (meth)acrylic acid ester of linear alkyl can be, for example: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-octyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, etc.

The (meth)acrylate of branched chain alkyl can be, for example: isopropyl (meth)acrylate, isobutyl (meth)acrylate, second butyl (meth)acrylate, second butyl (meth)acrylate Tributyl, 2-ethylbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, etc.

(Meth)acrylic esters with oxyalkyl groups can be, for example: (meth)acrylic acid substituted with alkoxy groups such as 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, etc. Alkyl esters, etc.

Examples of (meth)acrylates having a halogen atom include 3-fluoroethyl acrylate, 4-fluoropropyl acrylate, and the like.

Examples of (meth)acrylates having an alicyclic group include tricyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, and the like.

The (meth)acrylate having an aryl group may be, for example, benzyl (meth)acrylate or the like.

(Meth)acrylates with aryloxy groups can be, for example: 2-phenoxyethyl (meth)acrylate, 2-(2-phenoxyethoxy)ethyl (meth)acrylate, epoxy Ethane-modified nonylphenol (meth)acrylate, (meth)acrylate 2-(o-phenylphenoxy)ethyl ester, etc.

In some embodiments, it is preferable to use alkyl (meth)acrylate as (B) the second acrylate monomer. In some embodiments, it is more preferable to use linear alkyl (meth)acrylate as (B) the second acrylate monomer. In some embodiments, the carbon number of the alkyl group is preferably 2-14.

In some embodiments, (B) the second acrylate monomer includes at least two different acrylate monomers to adjust the adhesiveness and cohesion of the acrylic resin. In some embodiments, (B) the second acrylate monomer does not have a hydroxyl group, which can further reduce the water content of the optical adhesive layer 200 .

The acrylate oligomer formed by the copolymerization of (A) the first acrylate monomer and (B) the second acrylate monomer may not have a hydroxyl group, so as to reduce the water content of the subsequent optical adhesive layer 200 .

In one embodiment, the weight average molecular weight of (B) the second acrylate monomer is between 50-500. In another embodiment, the weight average molecular weight of (B) the second acrylate monomer is between 100-300.

[Hot starter]

In some embodiments, the thermal initiator may include an azo-based compound, a peroxide-based compound, or a combination thereof.

Azo compounds can be, for example, azobisisobutyronitrile (Azodiisobutyronitrile, AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'- Azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(isobutyric acid) Dimethyl, etc.

The peroxide-based compound may be, for example, tert-butyl peroxytrimethyl acetate, lauryl peroxide, benzoyl peroxide, and tert-butyl peroxylaurate.

In some embodiments, based on the total weight of (A) the first acrylate monomer and (B) the second acrylate monomer being 100 parts by weight, the ratio of the ingredients is as follows: (A) the first acrylate monomer 0.3-2.3 parts by weight, (B) the second acrylate monomer is 97.7-99.7 parts by weight, and the thermal initiator is 0.01-0.05 parts by weight.

In some embodiments, the sum of (A) the first acrylate monomer and (B) the second acrylate monomer is regarded as the total weight of the monomers, and (A) the first acrylate monomer having a polysilyl ether structure The weight accounts for 0.3-2.3wt% of the total monomer weight. When the weight exceeds 2.3wt%, it is easy to cause the polysiloxane structure to phase-separate in the mixed solution forming the optical adhesive layer, resulting in haze, and affecting the optical performance. When the weight is less than 0.3wt%, the polysilyl ether structure is not enough to reduce the water content of the optical adhesive layer, which will cause yellowing of the subsequent optical laminate.

Since the acrylate itself is hydrophilic, the water content in the optical adhesive and the subsequently formed optical adhesive layer can be reduced by using (A) the first acrylate monomer having a hydrophobic polysilyl ether structure. Moreover, by making (A) the first acrylate monomer and (B) the second acrylate monomer not have hydroxyl groups, the hydrophilicity of the monomers is reduced, and the optical adhesive and the subsequently formed optical adhesive layer can be further reduced. water content in. Thereby, the problem of yellowing of the subsequently formed optical laminate can be improved. In some embodiments, the moisture content in the optical adhesive layer is <0.5%, and the haze is <1%. In the reliability test of the optical laminate, the yellowing time is >200HR.

[Crosslinking agent]

In some embodiments, the crosslinking agent can help the optical adhesive to crosslink to form a network structure and improve the strength of the adhesive layer. In some embodiments, the crosslinking agent is a multifunctional group, for example, the crosslinking agent has at least two functional groups in its molecule, which can react with the polar functional groups of the optical adhesive.

In some embodiments, based on 100 parts by weight of the total weight of (A) the first acrylate monomer and (B) the second acrylate monomer, the amount of the crosslinking agent is 0.05-20 parts by weight. If the content of the crosslinking agent is too low, although part of the adhesive force can be increased, the cohesive force of the formed optical adhesive layer is insufficient, and foaming will occur during high temperature testing.

In some embodiments, the cross-linking agent may include an epoxy-based cross-linking agent, an isocyanate-based cross-linking agent, an imine-based cross-linking agent, a metal chelate-based cross-linking agent, or an aziridine-based cross-linking agent. One of them can be selected or mixed with several kinds of crosslinking agents. Examples of crosslinking agents may be, for example, trimethylolpropane triacrylate, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, toluene diisocyanate, hexaethylene Methyl diisocyanate, isophorone diisocyanate, diethylenetriamine, acetylacetone or ethyl acetylacetate with aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, barium, chromium Compounds coordinated with multivalent metals such as zirconium, diphenylmethane-4,4'-bis(1-aziridine formamide), trimethylolpropane-tri-β-aziridinyl propionate etc.

[Photoinitiator]

In some embodiments of the present application, the photoinitiator can be any compound capable of generating active free radicals, acids, etc. by the action of light, thereby enabling the photopolymerization reaction to start, and is not particularly limited.

In some embodiments, based on the total weight of (A) the first acrylate monomer and (B) the second acrylate monomer being 100 parts by weight, the photoinitiator is 0.05-10 parts by weight.

In some embodiments, the photoinitiator may include alkylphenones, acylphosphorus oxides, benzoyl compounds, benzophenones or other suitable photoinitiators. You can choose one of them or mix multiple photoinitiators to use. Examples of photoinitiators may for example be hydroxycyclohexylbenzophenone, 1,2-diphenylethanedione (Benzil), benzophenone (Benzophenone), benzoin (Benzoin), 1-hydroxycyclohexylphenyl Ketone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, methyl benzoylformate.

The optical adhesive, the photoinitiator and the crosslinking agent are mixed to form a mixed solution. And, the mixed solution is coated on the substrate 100 . Next, the optical adhesive layer 200 can be obtained by irradiating the mixed solution with light.

In some embodiments, the coating method may be, for example, bar coating method, knife coating method, roll coating method, sheet coating method, die coating method, gravure coating method and the like. In some embodiments, the coating device may include a doctor blade, a wire bar, a die coater, a twin roll coater, a gravure coater, and the like.

In some embodiments, the step of irradiating light may include using a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, etc. with a luminescence distribution. In some embodiments, the light irradiation step may include emitting X-rays with a wavelength of 1pm-10nm, ultraviolet rays with a wavelength of 10nm-400nm, visible light with a wavelength of 400nm-800nm, and the like. In some embodiments, the intensity of light irradiation may be 0.1 mW/cm ² to 400 mW/cm ² . In some embodiments, the amount of light irradiation may range from 10 mJ/cm ² to 1000 mJ/cm ² .

In some embodiments, the thickness of the optical adhesive layer 200 is 150-300 μm.

Next, please refer to Figure 2. The optical adhesive layer 200 in FIG. 1 can be used to adhere to the substrate 500 and the polarizer 300 to form the optical laminate 20 . In some embodiments, the optical laminate 20 further includes another substrate 400 disposed on the side of the polarizer 300 away from the substrate 500 , so that the polarizer 300 is sandwiched between the two substrates 400 / 500 .

Each element forming the optical laminate 20 will be described in detail below. It should be noted that FIG. 2 is an example of bonding polarizers, and the optical adhesive layer 200 can also be used for bonding other optical or non-optical components. In addition, each film layer of the polarizing plate 300 is only used for illustration, and the arrangement of each film layer can be changed according to actual needs, and some film layers can also be omitted or replaced according to actual needs.

[substrate]

In some embodiments, the substrate 400 and the substrate 500 can be flexible substrates or rigid substrates, and can be made of the same or different materials, such as glass, ceramics, polymers (such as polyimide), suitable for materials etc. In some embodiments, alkali-free glass can be used as the substrates 400 and 500 . In some embodiments, the substrate 400 and the substrate 500 may be a glass substrate of a liquid crystal display panel and a touch module, respectively. In some embodiments, the substrate 400 and the substrate 500 can be applied in a flexible display panel.

[polarizer]

In some embodiments, the polarizing plate 300 includes a protective film 340 disposed under the optical adhesive layer 200, a polarizing film 330 disposed under the protective film 340, an optical film 320 disposed under the polarizing film 330, and a polarizing film 320 disposed under the optical film 320. The lower adhesive layer 310.

[protective film]

In some embodiments, the protective film 340 can be a single-layer or multi-layer structure. The material of the protective film can be, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, and moisture barrier properties. Thermoplastic resins may include cellulose resins (for example: triacetate cellulose (TAC), diacetate cellulose (DAC), acetyl cellulose), acrylic resins (for example: polymethyl methacrylate Esters (poly(methyl methacrylate), PMMA), polyester resins (such as polyethylene terephthalate (PET), polyethylene naphthalate), olefin resins, polycarbonate resins, cyclo Olefin resin, oriented-polypropylene (OPP), polyethylene (polyethylene, PE), polypropylene (polypropylene, PP), cyclic olefin polymer (cyclic olefin polymer, COP), cyclic olefin copolymer (cyclic olefin copolymer, COC), or any combination of the above.

In addition, the material of the protective film can also be, for example, thermosetting resins such as (meth)acrylic, urethane, acrylic urethane, epoxy, polysiloxane, or ultraviolet rays. hardening resin. In addition, surface treatments such as anti-glare treatment, anti-reflection treatment, hard-coat treatment, anti-static treatment, or anti-fouling treatment may be further performed on the above-mentioned protective film.

[Polarizing film]

In some embodiments, the material of the polarizing film 330 can be polyvinyl alcohol (polyvinyl alcohol, PVA) resin film, which can be made by saponifying polyvinyl acetate resin. Examples of polyvinyl acetate resins include monopolymers of vinyl acetate, ie, polyvinyl acetate, copolymers of vinyl acetate and other monomers that can be copolymerized with vinyl acetate.

In some embodiments, polyvinyl alcohol (PVA) can be used as the polarizing film 330 after being treated. The foregoing treatment includes preparing a dyeing solution; immersing polyethylene in the dyeing solution; stretching polyvinyl alcohol; and drying.

[Optical film]

In some embodiments, the optical film 320 may include another protective film, retardation film, brightness enhancement film or other optical gain, alignment, compensation, turning, orthogonal, diffusion, protection, anti-sticking, scratch-resistant, anti-glare , reflection suppression, high refractive index and other helpful diaphragms.

In some embodiments, a retardation film is used as the optical film 320 .

In some embodiments, the optical film 320 can be a single-layer or multi-layer structure. The material of the optical film 320 can be, for example, a thermoplastic resin with excellent transparency, mechanical strength, thermal stability, and moisture barrier properties. Thermoplastic resins may include cellulose resins (for example: triacetate cellulose (TAC), diacetate cellulose (DAC), acetyl cellulose), acrylic resins (for example: polymethyl methacrylate Esters (poly(methyl methacrylate), PMMA), polyester resins (such as polyethylene terephthalate (PET), polyethylene naphthalate), olefin resins, polycarbonate resins, cyclo Olefin resin, oriented-polypropylene (OPP), polyethylene (polyethylene, PE), polypropylene (polypropylene, PP), cyclic olefin polymer (cyclic olefin polymer, COP), cyclic olefin copolymer (cyclic olefin copolymer, COC), or any combination of the above.

[adhesive layer]

In some embodiments, the adhesive layer 310 includes pressure sensitive adhesive (PSA), heat sensitive adhesive, solvent volatile adhesive, and UV curable adhesive, but not limited thereto. In some embodiments, the pressure sensitive adhesive comprises natural rubber, synthetic rubber, styrene block copolymer, (meth)acrylic block copolymer, polyvinyl ether, polyolefin, and poly(meth) Acrylate. In some embodiments, (meth)acrylic (or acrylate) refers to both acrylic and methacrylic. In other embodiments, the pressure sensitive adhesive comprises (meth)acrylate, rubber, thermoplastic elastomer, silicone, urethane, and combinations thereof. In some embodiments, the pressure sensitive adhesive is based on a (meth)acrylic pressure sensitive adhesive or based on at least one poly(meth)acrylate.

[Formation of polarizing plate]

In some embodiments, the upper and lower surfaces of the polarizing film 330 are provided with a water-based adhesive layer or a UV-curable adhesive (not shown). In some embodiments, the formation of the polarizing plate 300 includes coating a water-based adhesive or a UV-curable adhesive (not shown) between the upper and lower surfaces of the protective film 340, the optical film 320, and the polarizing film 330, and baking at a high temperature. Or after the ultraviolet light is irradiated, the adhesive layer 310 is pasted on the side of the optical film 320 .

In some embodiments, the step of coating the adhesive layer includes a method similar to that described above, which will not be repeated here.

[Formation of optical laminate]

In some embodiments, the substrate 400 and the polarizer 300 are bonded together by an adhesive layer 310 . In addition, the polarizing plate 300 and the substrate 500 bonded with the substrate 400 are bonded together through the optical adhesive layer 200 to obtain the optical laminate 20 . In this embodiment, the substrate 400 is a glass substrate of a liquid crystal display panel, and the substrate 500 is a touch module.

In some embodiments, one side of the polarizer 300 is 7-10 cm. One side of the substrate 400/500 is 9-12 cm, and one side of the optical adhesive layer 200 is 8-11 cm. In some embodiments, the optical adhesive layer 200 may cover sidewalls (not shown) of the polarizer 300 .

In the following, the present disclosure will provide several examples and comparative examples to more specifically illustrate the effects that can be achieved by the optical adhesive layer and the optical laminate including the optical adhesive according to the embodiments of the present disclosure, and the application of the present disclosure Contents Properties of the prepared optical adhesive layer and optical laminate. However, the following examples and comparative examples are for illustrative purposes only, and should not be construed as limitations on the implementation of the present disclosure. The unit "part" used below means a part by weight unless otherwise specified.

[Optical Adhesive]

The components of the following examples and comparative examples are shown in Table 1-2, and the types of components selected in the optical adhesive are described as follows.

[Table 1] Ingredients (parts by weight) Example 1 Example 2 Example 3 Acrylate Oligomer (A) the first acrylate monomer Methacrylate containing polysiloxane structure 0.5 2.0 2.0 polysiloxane degree of polymerization 100 100 10 (B) Second acrylate monomer n-butyl acrylate 59.7 57.6 57.6 lauryl methacrylate 39.8 40.4 40.4 hydroxyl monomer Hydroxyethyl Acrylate 0 0 0 hot starter Azo silicon compound 2,2'-Azobis(2,4-Dimethylvaleronitrile) 0.02 0.02 0.02

[Table 2] Ingredients (parts by weight) Comparative example 1 Comparative example 2 Comparative example 3 Acrylate Oligomer (A) the first acrylate monomer Methacrylate containing polysiloxane structure 0.0 2.0 2.5 polysiloxane degree of polymerization - 100 10 (B) Second acrylate monomer n-butyl acrylate 59.0 55.6 58.5 lauryl methacrylate 40.0 40.4 39.0 hydroxyl monomer Hydroxyethyl Acrylate 1.0 2.0 0 hot starter Azo silicon compound 2,2'-Azobis(2,4-Dimethylvaleronitrile) 0.02 0.02 0.02

。 It should be noted that the methacrylate containing polysilyl ether structure used in the (A) first acrylate monomer in Table 1 and Table 2 has the structure shown in the following chemical formula 2: [chemical formula 2]

.

As shown in Table 1 and Table 2, (A) the first acrylate monomer and (B) the second acrylate monomer can be copolymerized with a thermal initiator to form an acrylate oligomer with a weight average molecular weight of 650,000. The above copolymerization was continued at a temperature of 60°C for a period of 24HR.

[Optical Sheets Containing Optical Adhesive Layers]

Then, it was purged with nitrogen for 10 minutes to obtain a transparent viscous solution. 10 parts by weight of trimethylolpropane triacrylate as a crosslinking agent and 5 parts by weight of hydroxycyclohexylbenzophenone as a photoinitiator were added to the transparent viscous solution to form a mixed solution. The mixed solution was coated on a silicone-coated film as a release film at a thickness of 250 μm by a wire bar coater. Further, light was irradiated with a high pressure mercury lamp (UVC-02516S1AA02: manufactured by USHIO Denki Co., Ltd., illuminance: 200 mW/cm ² , irradiated light amount: 200 mJ/cm ² ) to obtain an optical sheet including an optical adhesive layer.

[Optical Laminate]

Next, a polarizing plate was prepared. Protective film: Acetyl cellulose with a trade name of "TG40" (manufactured by Fuji Chemical) was used. Polarizing film: After immersing polyvinyl alcohol (PVA) under the trade name "VinylonFilm#40" (manufactured by AICELLO) in the dyeing solution for 30 seconds, stretch it to 2 times in one direction and dry to produce a film thickness of 30 μm polarizing film. Wherein the dyeing solution is prepared by dissolving 20 parts by weight of boric acid, 0.2 parts by weight of iodine, and 0.5 parts by weight of potassium iodide in 480 parts by weight of water. Optical film: a retardation film of acetyl cellulose under the trade name "0-TAC" (manufactured by Fuji Chemical). Adhesive layer: The source is not limited, as long as it has adhesiveness, the examples and comparative examples used in the present invention were purchased from Eternal Chemical.

Coat the polyvinyl alcohol adhesive on the protective film with a wire rod coater, and attach the polarizing film to the protective film with a metal roller. Next, the polyvinyl alcohol adhesive was coated on the optical film by using a wire rod coater, and the polarizing film with the protective film attached was bonded on the optical film by using a metal roller. After the laminate formed by the protective film, the polarizing film and the optical film was fixed on the glass plate via adhesive tape, it was baked at high temperature (80C/2min). Next, the adhesive layer was bonded to the optical film side of the above-mentioned laminate to complete the preparation of the polarizing plate.

Next, an optical laminate is prepared.

The size of the aforementioned polarizing plate is processed to 8*8cm, the size of the Corning EXG alkali-free glass used as the substrate is processed to 10*10cm, and the size of the aforementioned optical sheet including the optical adhesive layer is processed to 9*9cm. After attaching the polarizing plate to the substrate through the adhesive layer, the optical adhesive layer is peeled off from the optical sheet and attached to the protective film side of the polarizing plate, and then another substrate is covered on the optical adhesive layer to complete the optical layer compound preparation.

[Evaluation]

The haze performance and water content of the obtained optical adhesive layer and the reliability test of the optical laminate were evaluated by the following methods.

[haze]

The size of the optical adhesive layer produced above was processed into a size of 40*40mm, and the haze of the optical adhesive layer was measured by a JIS K 7136 haze meter (type HM-150, manufactured by Murakami Color Technology Research Institute Co., Ltd.). When the haze ≦ 0.9%, the evaluation is good, otherwise it is bad.

[moisture content]

Take 0.01 g of the aforementioned optical adhesive layer and titrate it with a moisture titrator (Metrohm 870). The moisture content represents the amount of moisture contained in the sample.

[Reliability Test]

The aforementioned optical laminate was placed in a dry condition at a temperature of 105° C. for a weather resistance test. Subsequently, it was observed every 50 HR to visually observe whether the appearance of the polarizing plate was yellowed. When the yellowing time > 200HR, the evaluation is good, otherwise it is bad.

The relevant results are shown in Table 3-4:

[table 3] Evaluation Example 1 Example 2 Example 3 optical adhesive layer Haze (%) 0.50 0.67 0.53 Moisture content (%) 0.0 0.0 0.0 optical laminate Yellowing time (HR) 350 450 400

[Table 4] Evaluation Comparative example 1 Comparative example 2 Comparative example 3 optical adhesive layer Haze (%) 0.43 0.72 1.02 Moisture content (%) 1.5 0.9 0.0 optical laminate Yellowing time (HR) 50 200 600

It can be seen from the matching tables 1-4 above that the (A) first acrylate monomer having a polysilyl ether structure in Examples 1-3 can effectively reduce the moisture content of the optical adhesive layer. Furthermore, none of the acrylate oligomers in Examples 1-3 has a hydroxyl monomer, which further reduces the water content. Therefore, the optical adhesive layer of Examples 1-3 has a good haze ( ≦ 0.9%) and the optical laminate has a good yellowing time (>200HR).

In contrast, in Comparative Example 1 (A) the first acrylate monomer does not have a polysilyl ether structure, and the acrylate oligomer has a hydroxyl monomer, so the moisture content of the optical adhesive layer in Comparative Example 1 is high, and Optical laminates have poor onset of yellowing.

The acrylate oligomer in Comparative Example 2 has a hydroxyl monomer, so the optical adhesive layer in Comparative Example 2 has a high water content, and the optical laminate has poor yellowing time. In Comparative Example 3, although the first acrylate monomer (A) has a polysilyl ether structure, its content is too much, resulting in phase separation in the mixed solution, resulting in poor haze in the optical adhesive layer, and the optical laminate has Undesirable yellowing time.

To sum up, in the embodiment of the present invention, the water content of the optical adhesive layer is reduced by (A) the first acrylate monomer having a polysilyl ether structure. And the evaluation of haze and yellowing time is good due to the acrylate oligomer without hydroxyl monomer.

Several embodiments are summarized above so that those skilled in the art of the present invention can better understand the viewpoints of the embodiments of the present invention. Those with ordinary knowledge in the technical field of the present invention should understand that they can design or modify other processes and structures based on the embodiments of the present invention, so as to achieve the same purpose and/or advantages as the embodiments introduced here. Those skilled in the technical field of the present invention should also understand that such equivalent processes and structures do not deviate from the spirit and scope of the present invention, and they can, without departing from the spirit and scope of the present invention, Make all sorts of changes, substitutions, and substitutions.

10: Optical sheet 20: Optical film 100: Substrate 200: optical adhesive layer 300: polarizer 310: adhesive layer 320: Optical film 330: Polarizing film 340: protective film 400: Substrate 500: Substrate

To make the features and advantages of the present invention more comprehensible, different embodiments are specifically cited below and described in detail in conjunction with the attached drawings as follows: FIG. 1 is a schematic diagram illustrating an optical sheet including an optical adhesive layer according to some embodiments of the present invention. FIG. 2 is a schematic diagram illustrating an optical film using an optical adhesive layer according to some embodiments of the present invention.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in accordance with the standard practice in the industry, the various features are not drawn to scale and are used for illustrative purposes only. In fact, the dimensions of the elements may be arbitrarily expanded or reduced to clearly illustrate the features of the embodiments of the invention.

20: Optical film

200: optical adhesive layer

300: polarizer

310: adhesive layer

320: retardation film

330: Polarizing film

340: protective film

400: Substrate

500: Substrate

Claims (16)

An optical adhesive comprising: An acrylate oligomer, which is formed by copolymerization of (A) a first acrylate monomer and (B) a second acrylate monomer, wherein (A) the first acrylate monomer has a polysilyl ether structure; and A hot starter. The optical adhesive according to Claim 1, wherein (A) the first acrylate monomer has the structure shown in Chemical Formula 1 below: [Chemical Formula 1]

; wherein R ₁ , R ₄ , and R ₅ are each independently a hydrogen atom, or a C1-C5 alkyl group; R ₂ is a C1-C5 alkylene group or a single bond; R ₃ is a C1-C5 alkyl group; n is 5- An integer of 150. The optical adhesive according to claim 1, wherein (A) the first acrylate monomer has the structure shown in the following chemical formula 2: [chemical formula 2]

; wherein n is an integer of 5-150. The optical adhesive according to claim 1, wherein (A) the first acrylate monomer does not have a hydroxyl group. The optical adhesive according to claim 1, wherein the acrylate oligomer does not have a hydroxyl group. The optical adhesive according to claim 1, wherein (A) the first acrylate monomer comprises two acrylate monomers with different polysiloxane polymerization degrees. The optical adhesive of claim 1, wherein (B) the second acrylate monomer includes at least one selected from the group consisting of the following compounds: (meth)acrylates with alkyl groups, ( Meth)acrylate, (meth)acrylate with halogen atom, (meth)acrylate with alicyclic group, (meth)acrylate with aryl group, (meth)acrylic acid with aryloxy group Esters, and combinations of the above. Such as the optical adhesive of claim 1, wherein the total weight of (A) the first acrylate monomer and (B) the second acrylate monomer is 100 parts by weight as a basis, and the (A) first acrylate monomer is 0.3 -2.3 parts by weight, and (B) the second acrylate monomer is 97.7-99.7 parts by weight. Such as the optical adhesive of claim 1, wherein the total weight of (A) the first acrylate monomer and (B) the second acrylate monomer is 100 parts by weight as a basis, and the thermal initiator is 0.01-0.05 parts by weight . An optical adhesive layer comprising: The optical adhesive according to any one of claims 1-9; a photoinitiator; and a cross-linking agent. The optical adhesive layer according to claim 10, wherein the optical adhesive layer has a haze of 0.9% or less. The optical adhesive layer according to claim 10, wherein the moisture content of the optical adhesive layer is less than 0.5%. An optical laminate comprising: a substrate; a polarizer; and The optical adhesive layer according to any one of claims 10 to 12, wherein the optical adhesive layer is provided between the substrate and the polarizing plate. The optical laminate according to claim 13, wherein the optical laminate further comprises another substrate disposed on the side of the polarizer away from the substrate. The optical laminate according to claim 14, wherein the yellowing time of the optical laminate is greater than 200 hours. A method for forming an optical adhesive layer, comprising: An optical adhesive is prepared, wherein the preparation includes: an acrylate oligomer formed by copolymerizing (A) a first acrylate monomer and (B) a second acrylate monomer with a thermal initiator, wherein ( A) the first acrylate monomer has a polysilicon ether structure; mixing a photoinitiator and a crosslinking agent with the optical adhesive to form a mixed solution; coating the mixed solution on a substrate; and The mixed solution is irradiated with light to obtain an optical adhesive layer.

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